The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.
A diagnostic technique that incorporates the measurement of molecular diffusion (such as water or metabolites) for tissue assessment by MRI. The degree of molecular movement can be measured by changes of apparent diffusion coefficient (ADC) with time, as reflected by tissue microstructure. Diffusion MRI has been used to study BRAIN ISCHEMIA and tumor response to treatment.
The use of diffusion ANISOTROPY data from diffusion magnetic resonance imaging results to construct images based on the direction of the faster diffusing molecules.
The passive movement of molecules exceeding the rate expected by simple diffusion. No energy is expended in the process. It is achieved by the introduction of passively diffusing molecules to an enviroment or path that is more favorable to the movement of those molecules. Examples of facilitated diffusion are passive transport of hydrophilic substances across a lipid membrane through hydrophilic pores that traverse the membrane, and the sliding of a DNA BINDING PROTEIN along a strand of DNA.
A physical property showing different values in relation to the direction in or along which the measurement is made. The physical property may be with regard to thermal or electric conductivity or light refraction. In crystallography, it describes crystals whose index of refraction varies with the direction of the incident light. It is also called acolotropy and colotropy. The opposite of anisotropy is isotropy wherein the same values characterize the object when measured along axes in all directions.
A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.
The broad dissemination of new ideas, procedures, techniques, materials, and devices and the degree to which these are accepted and used.
A method used to study the lateral movement of MEMBRANE PROTEINS and LIPIDS. A small area of a cell membrane is bleached by laser light and the amount of time necessary for unbleached fluorescent marker-tagged proteins to diffuse back into the bleached site is a measurement of the cell membrane's fluidity. The diffusion coefficient of a protein or lipid in the membrane can be calculated from the data. (From Segen, Current Med Talk, 1995).
A method where a culturing surface inoculated with microbe is exposed to small disks containing known amounts of a chemical agent resulting in a zone of inhibition (usually in millimeters) of growth of the microbe corresponding to the susceptibility of the strain to the agent.
Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.
Methods developed to aid in the interpretation of ultrasound, radiographic images, etc., for diagnosis of disease.
A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
Improvement of the quality of a picture by various techniques, including computer processing, digital filtering, echocardiographic techniques, light and ultrastructural MICROSCOPY, fluorescence spectrometry and microscopy, scintigraphy, and in vitro image processing at the molecular level.
Broad plate of dense myelinated fibers that reciprocally interconnect regions of the cortex in all lobes with corresponding regions of the opposite hemisphere. The corpus callosum is located deep in the longitudinal fissure.
Devices used in a technique by which cells or tissues are grown in vitro or, by implantation, in vivo within chambers permeable to diffusion of solutes across the chamber walls. The chambers are used for studies of drug effects, osmotic responses, cytogenic and immunologic phenomena, metabolism, etc., and include tissue cages.
Computer-based representation of physical systems and phenomena such as chemical processes.
A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.
Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques.
The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The rate dynamics in chemical or physical systems.
Light-induced change in a chromophore, resulting in the loss of its absorption of light of a particular wave length. The photon energy causes a conformational change in the photoreceptor proteins affecting PHOTOTRANSDUCTION. This occurs naturally in the retina (ADAPTATION, OCULAR) on long exposure to bright light. Photobleaching presents problems when occurring in PHOTODYNAMIC THERAPY, and in FLUORESCENCE MICROSCOPY. On the other hand, this phenomenon is exploited in the technique, FLUORESCENCE RECOVERY AFTER PHOTOBLEACHING, allowing measurement of the movements of proteins and LIPIDS in the CELL MEMBRANE.
The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.
Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).
Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.
The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.
The statistical reproducibility of measurements (often in a clinical context), including the testing of instrumentation or techniques to obtain reproducible results. The concept includes reproducibility of physiological measurements, which may be used to develop rules to assess probability or prognosis, or response to a stimulus; reproducibility of occurrence of a condition; and reproducibility of experimental results.
The resistance that a gaseous or liquid system offers to flow when it is subjected to shear stress. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
WHITE MATTER pathway, flanked by nuclear masses, consisting of both afferent and efferent fibers projecting between the WHITE MATTER and the BRAINSTEM. It consists of three distinct parts: an anterior limb, posterior limb, and genu.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
The physical characteristics and processes of biological systems.
Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.
Binary classification measures to assess test results. Sensitivity or recall rate is the proportion of true positives. Specificity is the probability of correctly determining the absence of a condition. (From Last, Dictionary of Epidemiology, 2d ed)
Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.
Elements of limited time intervals, contributing to particular results or situations.
The motion of phospholipid molecules within the lipid bilayer, dependent on the classes of phospholipids present, their fatty acid composition and degree of unsaturation of the acyl chains, the cholesterol concentration, and temperature.
Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).
A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.
Measurement of the intensity and quality of fluorescence.
The movement of molecules from one location to another as effected by temperature changes.
Substances that reduce the growth or reproduction of BACTERIA.
The amount of a gas taken up, by the pulmonary capillary blood from the alveolar gas, per minute per unit of average pressure of the gradient of the gas across the BLOOD-AIR BARRIER.
Fibers that arise from cells within the cerebral cortex, pass through the medullary pyramid, and descend in the spinal cord. Many authorities say the pyramidal tracts include both the corticospinal and corticobulbar tracts.
Helium. A noble gas with the atomic symbol He, atomic number 2, and atomic weight 4.003. It is a colorless, odorless, tasteless gas that is not combustible and does not support combustion. It was first detected in the sun and is now obtained from natural gas. Medically it is used as a diluent for other gases, being especially useful with oxygen in the treatment of certain cases of respiratory obstruction, and as a vehicle for general anesthetics. (Dorland, 27th ed)
Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction.
Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.
Neural tracts connecting one part of the nervous system with another.
A complex sulfated polymer of galactose units, extracted from Gelidium cartilagineum, Gracilaria confervoides, and related red algae. It is used as a gel in the preparation of solid culture media for microorganisms, as a bulk laxative, in making emulsions, and as a supporting medium for immunodiffusion and immunoelectrophoresis.
The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)
Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.
A group of glucose polymers made by certain bacteria. Dextrans are used therapeutically as plasma volume expanders and anticoagulants. They are also commonly used in biological experimentation and in industry for a wide variety of purposes.
Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
The process of generating three-dimensional images by electronic, photographic, or other methods. For example, three-dimensional images can be generated by assembling multiple tomographic images with the aid of a computer, while photographic 3-D images (HOLOGRAPHY) can be made by exposing film to the interference pattern created when two laser light sources shine on an object.
In statistics, a technique for numerically approximating the solution of a mathematical problem by studying the distribution of some random variable, often generated by a computer. The name alludes to the randomness characteristic of the games of chance played at the gambling casinos in Monte Carlo. (From Random House Unabridged Dictionary, 2d ed, 1993)
Uptake of substances through the SKIN.
The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.
Colloids with a solid continuous phase and liquid as the dispersed phase; gels may be unstable when, due to temperature or other cause, the solid phase liquefies; the resulting colloid is called a sol.
Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.
Any visible result of a procedure which is caused by the procedure itself and not by the entity being analyzed. Common examples include histological structures introduced by tissue processing, radiographic images of structures that are not naturally present in living tissue, and products of chemical reactions that occur during analysis.
The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.
Fluids composed mainly of water found within the body.
Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.
A phthalic indicator dye that appears yellow-green in normal tear film and bright green in a more alkaline medium such as the aqueous humor.
An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.
Transmission of energy or mass by a medium involving movement of the medium itself. The circulatory movement that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed; Webster, 10th ed)
A family of spiro(isobenzofuran-1(3H),9'-(9H)xanthen)-3-one derivatives. These are used as dyes, as indicators for various metals, and as fluorescent labels in immunoassays.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Lipids, predominantly phospholipids, cholesterol and small amounts of glycolipids found in membranes including cellular and intracellular membranes. These lipids may be arranged in bilayers in the membranes with integral proteins between the layers and peripheral proteins attached to the outside. Membrane lipids are required for active transport, several enzymatic activities and membrane formation.
Statistical formulations or analyses which, when applied to data and found to fit the data, are then used to verify the assumptions and parameters used in the analysis. Examples of statistical models are the linear model, binomial model, polynomial model, two-parameter model, etc.
Any of various diseases affecting the white matter of the central nervous system.
Heavily myelinated fiber bundle of the TELENCEPHALON projecting from the hippocampal formation to the HYPOTHALAMUS. Some authorities consider the fornix part of the LIMBIC SYSTEM. The fimbria starts as a flattened band of axons arising from the subiculum and HIPPOCAMPUS, which then thickens to form the fornix.
A synthetic phospholipid used in liposomes and lipid bilayers for the study of biological membranes.
The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
A relatively common sequela of blunt head injury, characterized by a global disruption of axons throughout the brain. Associated clinical features may include NEUROBEHAVIORAL MANIFESTATIONS; PERSISTENT VEGETATIVE STATE; DEMENTIA; and other disorders.
The characteristic three-dimensional shape of a molecule.
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.
Condition of having pores or open spaces. This often refers to bones, bone implants, or bone cements, but can refer to the porous state of any solid substance.
A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.
Fluorescent probe capable of being conjugated to tissue and proteins. It is used as a label in fluorescent antibody staining procedures as well as protein- and amino acid-binding techniques.
Relating to the size of solids.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
Photochemistry is the study of chemical reactions induced by absorption of light, resulting in the promotion of electrons to higher energy levels and subsequent formation of radicals or excited molecules that can undergo various reaction pathways.
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.
Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries (see HYPOXIA, BRAIN). An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive HYDROCEPHALUS). (From Childs Nerv Syst 1992 Sep; 8(6):301-6)
A comprehensive map of the physical interconnections of an organism's neural networks. This modular organization of neuronal architecture is believed to underlie disease mechanisms and the biological development of the CENTRAL NERVOUS SYSTEM.
Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.
Characteristics or attributes of the outer boundaries of objects, including molecules.
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.
Neoplasms of the intracranial components of the central nervous system, including the cerebral hemispheres, basal ganglia, hypothalamus, thalamus, brain stem, and cerebellum. Brain neoplasms are subdivided into primary (originating from brain tissue) and secondary (i.e., metastatic) forms. Primary neoplasms are subdivided into benign and malignant forms. In general, brain tumors may also be classified by age of onset, histologic type, or presenting location in the brain.
Stable elementary particles having the smallest known positive charge, found in the nuclei of all elements. The proton mass is less than that of a neutron. A proton is the nucleus of the light hydrogen atom, i.e., the hydrogen ion.
Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
The part of a cell that contains the CYTOSOL and small structures excluding the CELL NUCLEUS; MITOCHONDRIA; and large VACUOLES. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)
Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.
A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)
Devices or objects in various imaging techniques used to visualize or enhance visualization by simulating conditions encountered in the procedure. Phantoms are used very often in procedures employing or measuring x-irradiation or radioactive material to evaluate performance. Phantoms often have properties similar to human tissue. Water demonstrates absorbing properties similar to normal tissue, hence water-filled phantoms are used to map radiation levels. Phantoms are used also as teaching aids to simulate real conditions with x-ray or ultrasonic machines. (From Iturralde, Dictionary and Handbook of Nuclear Medicine and Clinical Imaging, 1990)

A processive single-headed motor: kinesin superfamily protein KIF1A. (1/5959)

A single kinesin molecule can move "processively" along a microtubule for more than 1 micrometer before detaching from it. The prevailing explanation for this processive movement is the "walking model," which envisions that each of two motor domains (heads) of the kinesin molecule binds coordinately to the microtubule. This implies that each kinesin molecule must have two heads to "walk" and that a single-headed kinesin could not move processively. Here, a motor-domain construct of KIF1A, a single-headed kinesin superfamily protein, was shown to move processively along the microtubule for more than 1 micrometer. The movement along the microtubules was stochastic and fitted a biased Brownian-movement model.  (+info)

Transport of solutes through cartilage: permeability to large molecules. (2/5959)

A review of the transport of solutes through articular cartilage is given, with special reference to the effect of variations in matrix composition. Some physiological implications of our findings are discussed. Also, results of an experimental study of the permeability of articular cartilage to large globular proteins are presented. Because of the very low partition coefficients of large solutes between cartilage and an external solution new experimental techniques had to be devised, particularly for the study of diffusion. The partition coefficients of solutes were found to decrease very steeply with increase in size, up to serum albumin. There was, however, no further decrease for IGG. The diffusion coefficient of serum albumin in cartilage was relatively high (one quarter of the value in aqueous solution). These two facts taken together suggest that there may be a very small fraction of relatively large pores in cartilage through which the transport of large molecules is taking place. The permeability of cartilage to large molecules is extremely sensitive to variations in the glycosaminoglycan content: for a threefold increase in the latter there is a hundredfold decrease in the partition coefficient. For cartilage of fixed charge density around 0-19 m-equiv/g, there is no penetration at all of globular proteins of size equal to or larger than serum albumin.  (+info)

Increased lipophilicity and subsequent cell partitioning decrease passive transcellular diffusion of novel, highly lipophilic antioxidants. (3/5959)

Oxidative stress is considered a cause or propagator of acute and chronic disorders of the central nervous system. Novel 2, 4-diamino-pyrrolo[2,3-d]pyrimidines are potent inhibitors of iron-dependent lipid peroxidation, are cytoprotective in cell culture models of oxidative injury, and are neuroprotective in brain injury and ischemia models. The selection of lead candidates from this series required that they reach target cells deep within brain tissue in efficacious amounts after oral dosing. A homologous series of 26 highly lipophilic pyrrolopyrimidines was examined using cultured cell monolayers to understand the structure-permeability relationship and to use this information to predict brain penetration and residence time. Pyrrolopyrimidines were shown to be a more permeable structural class of membrane-interactive antioxidants where transepithelial permeability was inversely related to lipophilicity or to cell partitioning. Pyrrole substitutions influence cell partitioning where bulky hydrophobic groups increased partitioning and decreased permeability and smaller hydrophobic groups and more hydrophilic groups, especially those capable of weak hydrogen bonding, decreased partitioning, and increased permeability. Transmonolayer diffusion for these membrane-interactive antioxidants was limited mostly by desorption from the receiver-side membrane into the buffer. Thus, in this case, these in vitro cell monolayer models do not adequately mimic the in vivo situation by underestimating in vivo bioavailability of highly lipophilic compounds unless acceptors, such as serum proteins, are added to the receiving buffer.  (+info)

Novel, highly lipophilic antioxidants readily diffuse across the blood-brain barrier and access intracellular sites. (4/5959)

In an accompanying article, an in vitro assay for permeability predicts that membrane-protective, antioxidant 2,4-diamino-pyrrolo[2, 3-d]pyrimidines should have improved blood-brain barrier (BBB) permeation over previously described lipophilic antioxidants. Using a first-pass extraction method and brain/plasma quantification, we show here that two of the pyrrolopyrimidines, one of which is markedly less permeable, readily partition into rat brain. The efficiency of extraction was dependent on serum protein binding, and in situ efflux confirms the in vitro data showing that PNU-87663 is retained in brain longer than PNU-89843. By exploiting inherent fluorescence properties of PNU-87663, its distribution within brain and within cells in culture was demonstrated using confocal scanning laser microscopy. PNU-87663 rapidly partitioned into the cell membrane and equilibrates with cytoplasmic compartments via passive diffusion. Although partitioning of PNU-87663 favors intracytoplasmic lipid storage droplets, the compound was readily exchangeable as shown by efflux of compound from cells to buffer when protein was present. The results demonstrated that pyrrolopyrimidines were well suited for quickly accessing target cells within the central nervous system as well as in other target tissues.  (+info)

Free energy landscapes of encounter complexes in protein-protein association. (5/5959)

We report the computer generation of a high-density map of the thermodynamic properties of the diffusion-accessible encounter conformations of four receptor-ligand protein pairs, and use it to study the electrostatic and desolvation components of the free energy of association. Encounter complex conformations are generated by sampling the translational/rotational space of the ligand around the receptor, both at 5-A and zero surface-to-surface separations. We find that partial desolvation is always an important effect, and it becomes dominant for complexes in which one of the reactants is neutral or weakly charged. The interaction provides a slowly varying attractive force over a small but significant region of the molecular surface. In complexes with no strong charge complementarity this region surrounds the binding site, and the orientation of the ligand in the encounter conformation with the lowest desolvation free energy is similar to the one observed in the fully formed complex. Complexes with strong opposite charges exhibit two types of behavior. In the first group, represented by barnase/barstar, electrostatics exerts strong orientational steering toward the binding site, and desolvation provides some added adhesion within the local region of low electrostatic energy. In the second group, represented by the complex of kallikrein and pancreatic trypsin inhibitor, the overall stability results from the rather nonspecific electrostatic attraction, whereas the affinity toward the binding region is determined by desolvation interactions.  (+info)

pH-dependent conformational change of gastric mucin leads to sol-gel transition. (6/5959)

We present dynamic light scattering (DLS) and hydrophobic dye-binding data in an effort to elucidate a molecular mechanism for the ability of gastric mucin to form a gel at low pH, which is crucial to the barrier function of gastric mucus. DLS measurements of dilute mucin solutions were not indicative of intermolecular association, yet there was a steady fall in the measured diffusion coefficient with decreasing pH, suggesting an apparent increase in size. Taken together with the observed rise in depolarized scattering ratio with decreasing pH, these results suggest that gastric mucin undergoes a conformational change from a random coil at pH >/= 4 to an anisotropic, extended conformation at pH < 4. The increased binding of mucin to hydrophobic fluorescent with decreasing pH indicates that the change to an extended conformation is accompanied by exposure of hydrophobic binding sites. In concentrated mucin solutions, the structure factor S(q, t) derived from DLS measurements changed from a stretched exponential decay at pH 7 to a power-law decay at pH 2, which is characteristic of a sol-gel transition. We propose that the conformational change facilitates cross-links among mucin macromolecules through hydrophobic interactions at low pH, which in turn leads to a sol-gel transition when the mucin solution is sufficiently concentrated.  (+info)

Structural dynamics of ligand diffusion in the protein matrix: A study on a new myoglobin mutant Y(B10) Q(E7) R(E10). (7/5959)

A triple mutant of sperm whale myoglobin (Mb) [Leu(B10) --> Tyr, His(E7) --> Gln, and Thr(E10) --> Arg, called Mb-YQR], investigated by stopped-flow, laser photolysis, crystallography, and molecular dynamics (MD) simulations, proved to be quite unusual. Rebinding of photodissociated NO, O2, and CO from within the protein (in a "geminate" mode) allows us to reach general conclusions about dynamics and cavities in proteins. The 3D structure of oxy Mb-YQR shows that bound O2 makes two H-bonds with Tyr(B10)29 and Gln(E7)64; on deoxygenation, these two residues move toward the space occupied by O2. The bimolecular rate constant for NO binding is the same as for wild-type, but those for CO and O2 binding are reduced 10-fold. While there is no geminate recombination with O2 and CO, geminate rebinding of NO displays an unusually large and very slow component, which is pretty much abolished in the presence of xenon. These results and MD simulations suggest that the ligand migrates in the protein matrix to a major "secondary site," located beneath Tyr(B10)29 and accessible via the motion of Ile(G8)107; this site is different from the "primary site" identified by others who investigated the photolyzed state of wild-type Mb by crystallography. Our hypothesis may rationalize the O2 binding properties of Mb-YQR, and more generally to propose a mechanism of control of ligand binding and dissociation in hemeproteins based on the dynamics of side chains that may (or may not) allow access to and direct temporary sequestration of the dissociated ligand in a docking site within the protein. This interpretation suggests that very fast (picosecond) fluctuations of amino acid side chains may play a crucial role in controlling O2 delivery to tissue at a rate compatible with physiology.  (+info)

The forward rate of binding of surface-tethered reactants: effect of relative motion between two surfaces. (8/5959)

The reaction of molecules confined to two dimensions is of interest in cell adhesion, specifically for the reaction between cell surface receptors and substrate-bound ligand. We have developed a model to describe the overall rate of reaction of species that are bound to surfaces under relative motion, such that the Peclet number is order one or greater. The encounter rate between reactive species is calculated from solution of the two-dimensional convection-diffusion equation. The probability that each encounter will lead to binding depends on the intrinsic rate of reaction and the encounter duration. The encounter duration is obtained from the theory of first passage times. We find that the binding rate increases with relative velocity between the two surfaces, then reaches a plateau. This plateau indicates that the increase in the encounter rate is counterbalanced by the decrease in the encounter duration as the relative velocity increases. The binding rate is fully described by two dimensionless parameters, the Peclet number and the Damkohler number. We use this model to explain data from the cell adhesion literature by incorporating these rate laws into "adhesive dynamics" simulations to model the binding of a cell to a surface under flow. Leukocytes are known to display a "shear threshold effect" when binding selectin-coated surfaces under shear flow, defined as an increase in bind rate with shear; this effect, as calculated here, is due to an increase in collisions between receptor and ligand with increasing shear. The model can be used to explain other published data on the effect of wall shear rate on the binding of cells to surfaces, specifically the mild decrease in binding within a fixed area with increasing shear rate.  (+info)

Diffusion, in the context of medicine and physiology, refers to the process by which molecules move from an area of high concentration to an area of low concentration until they are evenly distributed throughout a space or solution. This passive transport mechanism does not require energy and relies solely on the random motion of particles. Diffusion is a vital process in many biological systems, including the exchange of gases in the lungs, the movement of nutrients and waste products across cell membranes, and the spread of drugs and other substances throughout tissues.

Diffusion Magnetic Resonance Imaging (MRI) is a non-invasive medical imaging technique that uses magnetic fields and radio waves to produce detailed images of the body's internal structures, particularly the brain and nervous system. In diffusion MRI, the movement of water molecules in biological tissues is measured and analyzed to generate contrast in the images based on the microstructural properties of the tissue.

Diffusion MRI is unique because it allows for the measurement of water diffusion in various directions, which can reveal important information about the organization and integrity of nerve fibers in the brain. This technique has been widely used in research and clinical settings to study a variety of neurological conditions, including stroke, traumatic brain injury, multiple sclerosis, and neurodegenerative diseases such as Alzheimer's disease.

In summary, diffusion MRI is a specialized type of MRI that measures the movement of water molecules in biological tissues to generate detailed images of the body's internal structures, particularly the brain and nervous system. It provides valuable information about the microstructural properties of tissues and has important applications in both research and clinical settings.

Diffusion Tensor Imaging (DTI) is a type of magnetic resonance imaging (MRI) technique that allows for the measurement and visualization of water diffusion in biological tissues, particularly in the brain. DTI provides information about the microstructural organization and integrity of nerve fibers within the brain by measuring the directionality of water diffusion in the brain's white matter tracts.

In DTI, a tensor is used to describe the three-dimensional diffusion properties of water molecules in each voxel (three-dimensional pixel) of an MRI image. The tensor provides information about the magnitude and direction of water diffusion, which can be used to calculate various diffusion metrics such as fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). These metrics provide insights into the structural properties of nerve fibers, including their orientation, density, and integrity.

DTI has numerous clinical applications, such as in the diagnosis and monitoring of neurological disorders like multiple sclerosis, traumatic brain injury, and neurodegenerative diseases. It can also be used for presurgical planning to identify critical white matter tracts that need to be preserved during surgery.

Facilitated diffusion is a type of passive transport that involves the movement of molecules or ions across a biological membrane with the assistance of a transport protein. Unlike simple diffusion, which occurs spontaneously down a concentration gradient, facilitated diffusion allows for the movement of substances against a concentration gradient, although it does not directly consume energy.

In facilitated diffusion, the transport protein binds to the substance (also known as the solute) on one side of the membrane and then changes shape, releasing the solute on the other side. This process can increase the rate of diffusion by providing a more efficient pathway for the solute to move through the membrane.

Examples of substances that use facilitated diffusion include glucose, amino acids, and ions such as sodium and potassium. These substances are too large or too polar to pass through the hydrophobic interior of the lipid bilayer that makes up the cell membrane, so they rely on transport proteins to help them move across the membrane.

It's important to note that facilitated diffusion is a passive process and does not require energy input from the cell. However, it is a regulated process, as the number of transport proteins in the membrane can be adjusted to control the rate of solute movement.

Anisotropy is a medical term that refers to the property of being directionally dependent, meaning that its properties or characteristics vary depending on the direction in which they are measured. In the context of medicine and biology, anisotropy can refer to various biological structures, tissues, or materials that exhibit different physical or chemical properties along different axes.

For example, certain types of collagen fibers in tendons and ligaments exhibit anisotropic behavior because they are stronger and stiffer when loaded along their long axis compared to being loaded perpendicular to it. Similarly, some brain tissues may show anisotropy due to the presence of nerve fibers that are organized in specific directions, leading to differences in electrical conductivity or diffusion properties depending on the orientation of the measurement.

Anisotropy is an important concept in various medical fields, including radiology, neurology, and materials science, as it can provide valuable information about the structure and function of biological tissues and help guide diagnostic and therapeutic interventions.

Myelinated nerve fibers are neuronal processes that are surrounded by a myelin sheath, a fatty insulating substance that is produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. This myelin sheath helps to increase the speed of electrical impulse transmission, also known as action potentials, along the nerve fiber. The myelin sheath has gaps called nodes of Ranvier where the electrical impulses can jump from one node to the next, which also contributes to the rapid conduction of signals. Myelinated nerve fibers are typically found in the peripheral nerves and the optic nerve, but not in the central nervous system (CNS) tracts that are located within the brain and spinal cord.

"Diffusion of Innovation" is a theory that describes how new ideas, products, or methods spread within a population or society. It was first introduced by Everett M. Rogers in his book "Diffusion of Innovations" in 1962. The theory explains the process and factors that influence the adoption and implementation of an innovation over time.

The diffusion of innovation model includes five stages:

1. Knowledge: Individuals become aware of the innovation but lack further information about it.
2. Persuasion: Individuals form a positive or negative opinion about the innovation and consider adopting it.
3. Decision: Individuals decide whether to adopt or reject the innovation.
4. Implementation: Individuals put the innovation into practice.
5. Confirmation: Individuals seek reinforcement of their decision to continue using the innovation or, in some cases, to reverse their decision and abandon it.

The theory also identifies five categories of adopters based on their willingness to adopt an innovation:

1. Innovators: Those who are willing to take risks and try new ideas early on.
2. Early Adopters: Those who have social networks, respect, and influence and are opinion leaders in their communities.
3. Early Majority: Those who deliberate before adopting an innovation but eventually adopt it.
4. Late Majority: Those who are skeptical about the innovation and only adopt it when it becomes mainstream or necessary.
5. Laggards: Those who resist change and are the last to adopt an innovation.

In medical contexts, diffusion of innovation theory can be applied to understand how new treatments, drugs, or medical devices spread within healthcare systems and communities. It can help healthcare professionals and policymakers develop strategies to promote evidence-based practices and improve patient outcomes.

Fluorescence Recovery After Photobleaching (FRAP) is a microscopy technique used to study the mobility and diffusion of molecules in biological samples, particularly within living cells. This technique involves the use of an intense laser beam to photobleach (or permanently disable) the fluorescence of a specific region within a sample that has been labeled with a fluorescent probe or dye. The recovery of fluorescence in this bleached area is then monitored over time, as unbleached molecules from adjacent regions move into the bleached area through diffusion or active transport.

The rate and extent of fluorescence recovery can provide valuable information about the mobility, binding interactions, and dynamics of the labeled molecules within their native environment. FRAP is widely used in cell biology research to investigate various processes such as protein-protein interactions, membrane fluidity, organelle dynamics, and gene expression regulation.

Disk diffusion antimicrobial susceptibility tests, also known as Kirby-Bauer tests, are laboratory methods used to determine the effectiveness of antibiotics against a specific bacterial strain. This test provides a simple and standardized way to estimate the susceptibility or resistance of a microorganism to various antibiotics.

In this method, a standardized inoculum of the bacterial suspension is spread evenly on the surface of an agar plate. Antibiotic-impregnated paper disks are then placed on the agar surface, allowing the diffusion of the antibiotic into the agar. After incubation, the zone of inhibition surrounding each disk is measured. The size of the zone of inhibition correlates with the susceptibility or resistance of the bacterial strain to that specific antibiotic.

The results are interpreted based on predefined criteria established by organizations such as the Clinical and Laboratory Standards Institute (CLSI) or the European Committee on Antimicrobial Susceptibility Testing (EUCAST). These interpretive criteria help categorize the susceptibility of the bacterial strain into one of three categories: susceptible, intermediate, or resistant.

It is important to note that disk diffusion tests have limitations and may not always accurately predict clinical outcomes. However, they remain a valuable tool in guiding empirical antibiotic therapy and monitoring antimicrobial resistance trends.

Biological models, also known as physiological models or organismal models, are simplified representations of biological systems, processes, or mechanisms that are used to understand and explain the underlying principles and relationships. These models can be theoretical (conceptual or mathematical) or physical (such as anatomical models, cell cultures, or animal models). They are widely used in biomedical research to study various phenomena, including disease pathophysiology, drug action, and therapeutic interventions.

Examples of biological models include:

1. Mathematical models: These use mathematical equations and formulas to describe complex biological systems or processes, such as population dynamics, metabolic pathways, or gene regulation networks. They can help predict the behavior of these systems under different conditions and test hypotheses about their underlying mechanisms.
2. Cell cultures: These are collections of cells grown in a controlled environment, typically in a laboratory dish or flask. They can be used to study cellular processes, such as signal transduction, gene expression, or metabolism, and to test the effects of drugs or other treatments on these processes.
3. Animal models: These are living organisms, usually vertebrates like mice, rats, or non-human primates, that are used to study various aspects of human biology and disease. They can provide valuable insights into the pathophysiology of diseases, the mechanisms of drug action, and the safety and efficacy of new therapies.
4. Anatomical models: These are physical representations of biological structures or systems, such as plastic models of organs or tissues, that can be used for educational purposes or to plan surgical procedures. They can also serve as a basis for developing more sophisticated models, such as computer simulations or 3D-printed replicas.

Overall, biological models play a crucial role in advancing our understanding of biology and medicine, helping to identify new targets for therapeutic intervention, develop novel drugs and treatments, and improve human health.

Computer-assisted image interpretation is the use of computer algorithms and software to assist healthcare professionals in analyzing and interpreting medical images. These systems use various techniques such as pattern recognition, machine learning, and artificial intelligence to help identify and highlight abnormalities or patterns within imaging data, such as X-rays, CT scans, MRI, and ultrasound images. The goal is to increase the accuracy, consistency, and efficiency of image interpretation, while also reducing the potential for human error. It's important to note that these systems are intended to assist healthcare professionals in their decision making process and not to replace them.

Computer-assisted image processing is a medical term that refers to the use of computer systems and specialized software to improve, analyze, and interpret medical images obtained through various imaging techniques such as X-ray, CT (computed tomography), MRI (magnetic resonance imaging), ultrasound, and others.

The process typically involves several steps, including image acquisition, enhancement, segmentation, restoration, and analysis. Image processing algorithms can be used to enhance the quality of medical images by adjusting contrast, brightness, and sharpness, as well as removing noise and artifacts that may interfere with accurate diagnosis. Segmentation techniques can be used to isolate specific regions or structures of interest within an image, allowing for more detailed analysis.

Computer-assisted image processing has numerous applications in medical imaging, including detection and characterization of lesions, tumors, and other abnormalities; assessment of organ function and morphology; and guidance of interventional procedures such as biopsies and surgeries. By automating and standardizing image analysis tasks, computer-assisted image processing can help to improve diagnostic accuracy, efficiency, and consistency, while reducing the potential for human error.

The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:

1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.

The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.

Image enhancement in the medical context refers to the process of improving the quality and clarity of medical images, such as X-rays, CT scans, MRI scans, or ultrasound images, to aid in the diagnosis and treatment of medical conditions. Image enhancement techniques may include adjusting contrast, brightness, or sharpness; removing noise or artifacts; or applying specialized algorithms to highlight specific features or structures within the image.

The goal of image enhancement is to provide clinicians with more accurate and detailed information about a patient's anatomy or physiology, which can help inform medical decision-making and improve patient outcomes.

The corpus callosum is the largest collection of white matter in the brain, consisting of approximately 200 million nerve fibers. It is a broad, flat band of tissue that connects the two hemispheres of the brain, allowing them to communicate and coordinate information processing. The corpus callosum plays a crucial role in integrating sensory, motor, and cognitive functions between the two sides of the brain. Damage to the corpus callosum can result in various neurological symptoms, including difficulties with movement, speech, memory, and social behavior.

Diffusion chambers are devices used in tissue culture and microbiology to maintain a sterile environment while allowing for the exchange of nutrients, gases, or other molecules between two separate environments. In the context of cell or tissue culture, diffusion chambers are often used to maintain cells or tissues in a controlled environment while allowing them to interact with other cells, molecules, or drugs present in a separate compartment.

Culture diffusion chambers typically consist of two compartments separated by a semi-permeable membrane that allows for the passive diffusion of small molecules. One compartment contains the cells or tissues of interest, while the other compartment may contain various nutrients, growth factors, drugs, or other substances to be tested.

The use of diffusion chambers in cell and tissue culture has several advantages, including:

1. Maintaining a sterile environment for the cells or tissues being cultured.
2. Allowing for the exchange of nutrients, gases, or other molecules between the two compartments.
3. Enabling the study of cell-cell interactions and the effects of various substances on cell behavior without direct contact between the cells and the test substance.
4. Providing a means to culture sensitive or difficult-to-grow cells in a controlled environment.

Diffusion chambers are widely used in research settings, particularly in the fields of cell biology, tissue engineering, and drug development.

A computer simulation is a process that involves creating a model of a real-world system or phenomenon on a computer and then using that model to run experiments and make predictions about how the system will behave under different conditions. In the medical field, computer simulations are used for a variety of purposes, including:

1. Training and education: Computer simulations can be used to create realistic virtual environments where medical students and professionals can practice their skills and learn new procedures without risk to actual patients. For example, surgeons may use simulation software to practice complex surgical techniques before performing them on real patients.
2. Research and development: Computer simulations can help medical researchers study the behavior of biological systems at a level of detail that would be difficult or impossible to achieve through experimental methods alone. By creating detailed models of cells, tissues, organs, or even entire organisms, researchers can use simulation software to explore how these systems function and how they respond to different stimuli.
3. Drug discovery and development: Computer simulations are an essential tool in modern drug discovery and development. By modeling the behavior of drugs at a molecular level, researchers can predict how they will interact with their targets in the body and identify potential side effects or toxicities. This information can help guide the design of new drugs and reduce the need for expensive and time-consuming clinical trials.
4. Personalized medicine: Computer simulations can be used to create personalized models of individual patients based on their unique genetic, physiological, and environmental characteristics. These models can then be used to predict how a patient will respond to different treatments and identify the most effective therapy for their specific condition.

Overall, computer simulations are a powerful tool in modern medicine, enabling researchers and clinicians to study complex systems and make predictions about how they will behave under a wide range of conditions. By providing insights into the behavior of biological systems at a level of detail that would be difficult or impossible to achieve through experimental methods alone, computer simulations are helping to advance our understanding of human health and disease.

An algorithm is not a medical term, but rather a concept from computer science and mathematics. In the context of medicine, algorithms are often used to describe step-by-step procedures for diagnosing or managing medical conditions. These procedures typically involve a series of rules or decision points that help healthcare professionals make informed decisions about patient care.

For example, an algorithm for diagnosing a particular type of heart disease might involve taking a patient's medical history, performing a physical exam, ordering certain diagnostic tests, and interpreting the results in a specific way. By following this algorithm, healthcare professionals can ensure that they are using a consistent and evidence-based approach to making a diagnosis.

Algorithms can also be used to guide treatment decisions. For instance, an algorithm for managing diabetes might involve setting target blood sugar levels, recommending certain medications or lifestyle changes based on the patient's individual needs, and monitoring the patient's response to treatment over time.

Overall, algorithms are valuable tools in medicine because they help standardize clinical decision-making and ensure that patients receive high-quality care based on the latest scientific evidence.

Medical Definition:

Magnetic Resonance Imaging (MRI) is a non-invasive diagnostic imaging technique that uses a strong magnetic field and radio waves to create detailed cross-sectional or three-dimensional images of the internal structures of the body. The patient lies within a large, cylindrical magnet, and the scanner detects changes in the direction of the magnetic field caused by protons in the body. These changes are then converted into detailed images that help medical professionals to diagnose and monitor various medical conditions, such as tumors, injuries, or diseases affecting the brain, spinal cord, heart, blood vessels, joints, and other internal organs. MRI does not use radiation like computed tomography (CT) scans.

I'm sorry for any confusion, but there seems to be a misunderstanding. Mathematics is not a medical term; it is a branch of science dedicated to the study of numbers, shapes, and structures. However, mathematics does have many applications in medicine, such as in modeling disease spread, analyzing medical images, or designing clinical trials. If you have any questions related to mathematics in a medical context, I'd be happy to help clarify those for you!

Medical definitions of water generally describe it as a colorless, odorless, tasteless liquid that is essential for all forms of life. It is a universal solvent, making it an excellent medium for transporting nutrients and waste products within the body. Water constitutes about 50-70% of an individual's body weight, depending on factors such as age, sex, and muscle mass.

In medical terms, water has several important functions in the human body:

1. Regulation of body temperature through perspiration and respiration.
2. Acting as a lubricant for joints and tissues.
3. Facilitating digestion by helping to break down food particles.
4. Transporting nutrients, oxygen, and waste products throughout the body.
5. Helping to maintain healthy skin and mucous membranes.
6. Assisting in the regulation of various bodily functions, such as blood pressure and heart rate.

Dehydration can occur when an individual does not consume enough water or loses too much fluid due to illness, exercise, or other factors. This can lead to a variety of symptoms, including dry mouth, fatigue, dizziness, and confusion. Severe dehydration can be life-threatening if left untreated.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Photobleaching is a process in microscopy where fluorescent molecules, used as labels to visualize specific structures or proteins within cells, lose their ability to fluoresce after exposure to high-intensity light. This can occur due to the chemical alteration of the fluorophore's structure, which causes a loss of its ability to absorb and emit light. Photobleaching is often used in fluorescence recovery after photobleaching (FRAP) experiments to measure the mobility and diffusion rates of proteins within living cells. However, it can also be a limitation in long-term imaging studies as it reduces the signal-to-noise ratio and can lead to the loss of important information.

Biophysics is a interdisciplinary field that combines the principles and methods of physics with those of biology to study biological systems and phenomena. It involves the use of physical theories, models, and techniques to understand and explain the properties, functions, and behaviors of living organisms and their constituents, such as cells, proteins, and DNA.

Biophysics can be applied to various areas of biology, including molecular biology, cell biology, neuroscience, and physiology. It can help elucidate the mechanisms of biological processes at the molecular and cellular levels, such as protein folding, ion transport, enzyme kinetics, gene expression, and signal transduction. Biophysical methods can also be used to develop diagnostic and therapeutic tools for medical applications, such as medical imaging, drug delivery, and gene therapy.

Examples of biophysical techniques include X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, electron microscopy, fluorescence microscopy, atomic force microscopy, and computational modeling. These methods allow researchers to probe the structure, dynamics, and interactions of biological molecules and systems with high precision and resolution, providing insights into their functions and behaviors.

Microbial sensitivity tests, also known as antibiotic susceptibility tests (ASTs) or bacterial susceptibility tests, are laboratory procedures used to determine the effectiveness of various antimicrobial agents against specific microorganisms isolated from a patient's infection. These tests help healthcare providers identify which antibiotics will be most effective in treating an infection and which ones should be avoided due to resistance. The results of these tests can guide appropriate antibiotic therapy, minimize the potential for antibiotic resistance, improve clinical outcomes, and reduce unnecessary side effects or toxicity from ineffective antimicrobials.

There are several methods for performing microbial sensitivity tests, including:

1. Disk diffusion method (Kirby-Bauer test): A standardized paper disk containing a predetermined amount of an antibiotic is placed on an agar plate that has been inoculated with the isolated microorganism. After incubation, the zone of inhibition around the disk is measured to determine the susceptibility or resistance of the organism to that particular antibiotic.
2. Broth dilution method: A series of tubes or wells containing decreasing concentrations of an antimicrobial agent are inoculated with a standardized microbial suspension. After incubation, the minimum inhibitory concentration (MIC) is determined by observing the lowest concentration of the antibiotic that prevents visible growth of the organism.
3. Automated systems: These use sophisticated technology to perform both disk diffusion and broth dilution methods automatically, providing rapid and accurate results for a wide range of microorganisms and antimicrobial agents.

The interpretation of microbial sensitivity test results should be done cautiously, considering factors such as the site of infection, pharmacokinetics and pharmacodynamics of the antibiotic, potential toxicity, and local resistance patterns. Regular monitoring of susceptibility patterns and ongoing antimicrobial stewardship programs are essential to ensure optimal use of these tests and to minimize the development of antibiotic resistance.

The term "Theoretical Models" is used in various scientific fields, including medicine, to describe a representation of a complex system or phenomenon. It is a simplified framework that explains how different components of the system interact with each other and how they contribute to the overall behavior of the system. Theoretical models are often used in medical research to understand and predict the outcomes of diseases, treatments, or public health interventions.

A theoretical model can take many forms, such as mathematical equations, computer simulations, or conceptual diagrams. It is based on a set of assumptions and hypotheses about the underlying mechanisms that drive the system. By manipulating these variables and observing the effects on the model's output, researchers can test their assumptions and generate new insights into the system's behavior.

Theoretical models are useful for medical research because they allow scientists to explore complex systems in a controlled and systematic way. They can help identify key drivers of disease or treatment outcomes, inform the design of clinical trials, and guide the development of new interventions. However, it is important to recognize that theoretical models are simplifications of reality and may not capture all the nuances and complexities of real-world systems. Therefore, they should be used in conjunction with other forms of evidence, such as experimental data and observational studies, to inform medical decision-making.

Biological transport refers to the movement of molecules, ions, or solutes across biological membranes or through cells in living organisms. This process is essential for maintaining homeostasis, regulating cellular functions, and enabling communication between cells. There are two main types of biological transport: passive transport and active transport.

Passive transport does not require the input of energy and includes:

1. Diffusion: The random movement of molecules from an area of high concentration to an area of low concentration until equilibrium is reached.
2. Osmosis: The diffusion of solvent molecules (usually water) across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.
3. Facilitated diffusion: The assisted passage of polar or charged substances through protein channels or carriers in the cell membrane, which increases the rate of diffusion without consuming energy.

Active transport requires the input of energy (in the form of ATP) and includes:

1. Primary active transport: The direct use of ATP to move molecules against their concentration gradient, often driven by specific transport proteins called pumps.
2. Secondary active transport: The coupling of the movement of one substance down its electrochemical gradient with the uphill transport of another substance, mediated by a shared transport protein. This process is also known as co-transport or counter-transport.

Reproducibility of results in a medical context refers to the ability to obtain consistent and comparable findings when a particular experiment or study is repeated, either by the same researcher or by different researchers, following the same experimental protocol. It is an essential principle in scientific research that helps to ensure the validity and reliability of research findings.

In medical research, reproducibility of results is crucial for establishing the effectiveness and safety of new treatments, interventions, or diagnostic tools. It involves conducting well-designed studies with adequate sample sizes, appropriate statistical analyses, and transparent reporting of methods and findings to allow other researchers to replicate the study and confirm or refute the results.

The lack of reproducibility in medical research has become a significant concern in recent years, as several high-profile studies have failed to produce consistent findings when replicated by other researchers. This has led to increased scrutiny of research practices and a call for greater transparency, rigor, and standardization in the conduct and reporting of medical research.

Viscosity is a physical property of a fluid that describes its resistance to flow. In medical terms, viscosity is often discussed in relation to bodily fluids such as blood or synovial fluid (found in joints). The unit of measurement for viscosity is the poise, although it is more commonly expressed in millipascals-second (mPa.s) in SI units. Highly viscous fluids flow more slowly than less viscous fluids. Changes in the viscosity of bodily fluids can have significant implications for health and disease; for example, increased blood viscosity has been associated with cardiovascular diseases, while decreased synovial fluid viscosity can contribute to joint pain and inflammation in conditions like osteoarthritis.

The internal capsule is a critical structure in the brain that consists of a bundle of white matter fibers (nerve tracts) located deep within the cerebral hemispheres. It serves as a major pathway for the transmission of motor, sensory, and cognitive information between different regions of the brain. The internal capsule is divided into several segments, including the anterior limb, genu, posterior limb, and retrolentiform and sublentiform parts.

The fibers within the internal capsule can be categorized into three groups: corticopontine fibers, corticospinal and corticobulbar fibers, and thalamocortical fibers. Corticopontine fibers originate from the cerebral cortex and terminate in the pons. Corticospinal and corticobulbar fibers are responsible for motor functions, with corticospinal fibers controlling movements of the trunk and limbs, while corticobulbar fibers control movements of the face and head. Thalamocortical fibers carry sensory information from the thalamus to the cerebral cortex.

Damage to the internal capsule can result in various neurological deficits, depending on the specific location and extent of the injury. These may include motor impairments, sensory loss, cognitive dysfunction, or a combination of these symptoms.

A cell membrane, also known as the plasma membrane, is a thin semi-permeable phospholipid bilayer that surrounds all cells in animals, plants, and microorganisms. It functions as a barrier to control the movement of substances in and out of the cell, allowing necessary molecules such as nutrients, oxygen, and signaling molecules to enter while keeping out harmful substances and waste products. The cell membrane is composed mainly of phospholipids, which have hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails. This unique structure allows the membrane to be flexible and fluid, yet selectively permeable. Additionally, various proteins are embedded in the membrane that serve as channels, pumps, receptors, and enzymes, contributing to the cell's overall functionality and communication with its environment.

Biophysical phenomena refer to the observable events and processes that occur in living organisms, which can be explained and studied using the principles and methods of physics. These phenomena can include a wide range of biological processes at various levels of organization, from molecular interactions to whole-organism behaviors. Examples of biophysical phenomena include the mechanics of muscle contraction, the electrical activity of neurons, the transport of molecules across cell membranes, and the optical properties of biological tissues. By applying physical theories and techniques to the study of living systems, biophysicists seek to better understand the fundamental principles that govern life and to develop new approaches for diagnosing and treating diseases.

A chemical model is a simplified representation or description of a chemical system, based on the laws of chemistry and physics. It is used to explain and predict the behavior of chemicals and chemical reactions. Chemical models can take many forms, including mathematical equations, diagrams, and computer simulations. They are often used in research, education, and industry to understand complex chemical processes and develop new products and technologies.

For example, a chemical model might be used to describe the way that atoms and molecules interact in a particular reaction, or to predict the properties of a new material. Chemical models can also be used to study the behavior of chemicals at the molecular level, such as how they bind to each other or how they are affected by changes in temperature or pressure.

It is important to note that chemical models are simplifications of reality and may not always accurately represent every aspect of a chemical system. They should be used with caution and validated against experimental data whenever possible.

In the context of medicine and physiology, permeability refers to the ability of a tissue or membrane to allow the passage of fluids, solutes, or gases. It is often used to describe the property of the capillary walls, which control the exchange of substances between the blood and the surrounding tissues.

The permeability of a membrane can be influenced by various factors, including its molecular structure, charge, and the size of the molecules attempting to pass through it. A more permeable membrane allows for easier passage of substances, while a less permeable membrane restricts the movement of substances.

In some cases, changes in permeability can have significant consequences for health. For example, increased permeability of the blood-brain barrier (a specialized type of capillary that regulates the passage of substances into the brain) has been implicated in a number of neurological conditions, including multiple sclerosis, Alzheimer's disease, and traumatic brain injury.

Sensitivity and specificity are statistical measures used to describe the performance of a diagnostic test or screening tool in identifying true positive and true negative results.

* Sensitivity refers to the proportion of people who have a particular condition (true positives) who are correctly identified by the test. It is also known as the "true positive rate" or "recall." A highly sensitive test will identify most or all of the people with the condition, but may also produce more false positives.
* Specificity refers to the proportion of people who do not have a particular condition (true negatives) who are correctly identified by the test. It is also known as the "true negative rate." A highly specific test will identify most or all of the people without the condition, but may also produce more false negatives.

In medical testing, both sensitivity and specificity are important considerations when evaluating a diagnostic test. High sensitivity is desirable for screening tests that aim to identify as many cases of a condition as possible, while high specificity is desirable for confirmatory tests that aim to rule out the condition in people who do not have it.

It's worth noting that sensitivity and specificity are often influenced by factors such as the prevalence of the condition in the population being tested, the threshold used to define a positive result, and the reliability and validity of the test itself. Therefore, it's important to consider these factors when interpreting the results of a diagnostic test.

Fluorescent dyes are substances that emit light upon excitation by absorbing light of a shorter wavelength. In a medical context, these dyes are often used in various diagnostic tests and procedures to highlight or mark certain structures or substances within the body. For example, fluorescent dyes may be used in imaging techniques such as fluorescence microscopy or fluorescence angiography to help visualize cells, tissues, or blood vessels. These dyes can also be used in flow cytometry to identify and sort specific types of cells. The choice of fluorescent dye depends on the specific application and the desired properties, such as excitation and emission spectra, quantum yield, and photostability.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Membrane fluidity, in the context of cell biology, refers to the ability of the phospholipid bilayer that makes up the cell membrane to change its structure and organization in response to various factors. The membrane is not a static structure but rather a dynamic one, with its lipids constantly moving and changing position.

Membrane fluidity is determined by the fatty acid composition of the phospholipids that make up the bilayer. Lipids with unsaturated fatty acids have kinks in their hydrocarbon chains, which prevent them from packing closely together and increase membrane fluidity. In contrast, lipids with saturated fatty acids can pack closely together, reducing membrane fluidity.

Membrane fluidity is important for various cellular processes, including the movement of proteins within the membrane, the fusion of vesicles with the membrane during exocytosis and endocytosis, and the ability of the membrane to respond to changes in temperature and other environmental factors. Abnormalities in membrane fluidity have been linked to various diseases, including cancer, neurological disorders, and infectious diseases.

Magnetic Resonance Spectroscopy (MRS) is a non-invasive diagnostic technique that provides information about the biochemical composition of tissues, including their metabolic state. It is often used in conjunction with Magnetic Resonance Imaging (MRI) to analyze various metabolites within body tissues, such as the brain, heart, liver, and muscles.

During MRS, a strong magnetic field, radio waves, and a computer are used to produce detailed images and data about the concentration of specific metabolites in the targeted tissue or organ. This technique can help detect abnormalities related to energy metabolism, neurotransmitter levels, pH balance, and other biochemical processes, which can be useful for diagnosing and monitoring various medical conditions, including cancer, neurological disorders, and metabolic diseases.

There are different types of MRS, such as Proton (^1^H) MRS, Phosphorus-31 (^31^P) MRS, and Carbon-13 (^13^C) MRS, each focusing on specific elements or metabolites within the body. The choice of MRS technique depends on the clinical question being addressed and the type of information needed for diagnosis or monitoring purposes.

Cell membrane permeability refers to the ability of various substances, such as molecules and ions, to pass through the cell membrane. The cell membrane, also known as the plasma membrane, is a thin, flexible barrier that surrounds all cells, controlling what enters and leaves the cell. Its primary function is to protect the cell's internal environment and maintain homeostasis.

The permeability of the cell membrane depends on its structure, which consists of a phospholipid bilayer interspersed with proteins. The hydrophilic (water-loving) heads of the phospholipids face outward, while the hydrophobic (water-fearing) tails face inward, creating a barrier that is generally impermeable to large, polar, or charged molecules.

However, specific proteins within the membrane, called channels and transporters, allow certain substances to cross the membrane. Channels are protein structures that span the membrane and provide a pore for ions or small uncharged molecules to pass through. Transporters, on the other hand, are proteins that bind to specific molecules and facilitate their movement across the membrane, often using energy in the form of ATP.

The permeability of the cell membrane can be influenced by various factors, such as temperature, pH, and the presence of certain chemicals or drugs. Changes in permeability can have significant consequences for the cell's function and survival, as they can disrupt ion balances, nutrient uptake, waste removal, and signal transduction.

Fluorescence spectrometry is a type of analytical technique used to investigate the fluorescent properties of a sample. It involves the measurement of the intensity of light emitted by a substance when it absorbs light at a specific wavelength and then re-emits it at a longer wavelength. This process, known as fluorescence, occurs because the absorbed energy excites electrons in the molecules of the substance to higher energy states, and when these electrons return to their ground state, they release the excess energy as light.

Fluorescence spectrometry typically measures the emission spectrum of a sample, which is a plot of the intensity of emitted light versus the wavelength of emission. This technique can be used to identify and quantify the presence of specific fluorescent molecules in a sample, as well as to study their photophysical properties.

Fluorescence spectrometry has many applications in fields such as biochemistry, environmental science, and materials science. For example, it can be used to detect and measure the concentration of pollutants in water samples, to analyze the composition of complex biological mixtures, or to study the properties of fluorescent nanomaterials.

Thermal diffusion, also known as thermodiffusion or the Soret effect, is not a term that has a specific medical definition. It is a physical phenomenon that occurs in a mixture of two or more substances when there is a temperature gradient present. As a result, the components of the mixture tend to separate based on their differences in molecular weight and heat conductivity.

However, thermal diffusion can have indirect applications in certain medical contexts, such as in the development of medical devices or in understanding the behavior of biological systems at the molecular level. For instance, it may be relevant in the design of microfluidic devices used for lab-on-a-chip applications, where precise control over the movement and separation of molecules is essential.

In summary, while thermal diffusion itself does not have a medical definition, its principles and applications can be significant in certain medical and biomedical research contexts.

Anti-bacterial agents, also known as antibiotics, are a type of medication used to treat infections caused by bacteria. These agents work by either killing the bacteria or inhibiting their growth and reproduction. There are several different classes of anti-bacterial agents, including penicillins, cephalosporins, fluoroquinolones, macrolides, and tetracyclines, among others. Each class of antibiotic has a specific mechanism of action and is used to treat certain types of bacterial infections. It's important to note that anti-bacterial agents are not effective against viral infections, such as the common cold or flu. Misuse and overuse of antibiotics can lead to antibiotic resistance, which is a significant global health concern.

Pulmonary diffusing capacity, also known as pulmonary diffusion capacity, is a measure of the ability of the lungs to transfer gas from the alveoli to the bloodstream. It is often used to assess the severity of lung diseases such as chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis.

The most common measurement of pulmonary diffusing capacity is the diffusing capacity for carbon monoxide (DLCO), which reflects the transfer of carbon monoxide from the alveoli to the red blood cells in the capillaries. The DLCO is measured during a spirometry test, which involves breathing in a small amount of carbon monoxide and then measuring how much of it is exhaled.

A reduced DLCO may indicate a problem with the lung's ability to transfer oxygen to the blood, which can be caused by a variety of factors including damage to the alveoli or capillaries, thickening of the alveolar membrane, or a decrease in the surface area available for gas exchange.

It is important to note that other factors such as hemoglobin concentration, carboxyhemoglobin level, and lung volume can also affect the DLCO value, so these should be taken into account when interpreting the results of a diffusing capacity test.

The pyramidal tracts, also known as the corticospinal tracts, are bundles of nerve fibers that run through the brainstem and spinal cord, originating from the cerebral cortex. These tracts are responsible for transmitting motor signals from the brain to the muscles, enabling voluntary movement and control of the body.

The pyramidal tracts originate from the primary motor cortex in the frontal lobe of the brain and decussate (cross over) in the lower medulla oblongata before continuing down the spinal cord. The left pyramidal tract controls muscles on the right side of the body, while the right pyramidal tract controls muscles on the left side of the body.

Damage to the pyramidal tracts can result in various motor impairments, such as weakness or paralysis, spasticity, and loss of fine motor control, depending on the location and extent of the damage.

Helium is not a medical term, but it's a chemical element with symbol He and atomic number 2. It's a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gases section of the periodic table. In medicine, helium is sometimes used in medical settings for its unique properties, such as being less dense than air, which can help improve the delivery of oxygen to patients with respiratory conditions. For example, heliox, a mixture of helium and oxygen, may be used to reduce the work of breathing in patients with conditions like chronic obstructive pulmonary disease (COPD) or asthma. Additionally, helium is also used in cryogenic medical equipment and in magnetic resonance imaging (MRI) machines to cool the superconducting magnets.

Immunodiffusion is a laboratory technique used in immunology to detect and measure the presence of specific antibodies or antigens in a sample. It is based on the principle of diffusion, where molecules move from an area of high concentration to an area of low concentration until they reach equilibrium. In this technique, a sample containing an unknown quantity of antigen or antibody is placed in a gel or agar medium that contains a known quantity of antibody or antigen, respectively.

The two substances then diffuse towards each other and form a visible precipitate at the point where they meet and reach equivalence, which indicates the presence and quantity of the specific antigen or antibody in the sample. There are several types of immunodiffusion techniques, including radial immunodiffusion (RID) and double immunodiffusion (Ouchterlony technique). These techniques are widely used in diagnostic laboratories to identify and measure various antigens and antibodies, such as those found in infectious diseases, autoimmune disorders, and allergic reactions.

Brain mapping is a broad term that refers to the techniques used to understand the structure and function of the brain. It involves creating maps of the various cognitive, emotional, and behavioral processes in the brain by correlating these processes with physical locations or activities within the nervous system. Brain mapping can be accomplished through a variety of methods, including functional magnetic resonance imaging (fMRI), positron emission tomography (PET) scans, electroencephalography (EEG), and others. These techniques allow researchers to observe which areas of the brain are active during different tasks or thoughts, helping to shed light on how the brain processes information and contributes to our experiences and behaviors. Brain mapping is an important area of research in neuroscience, with potential applications in the diagnosis and treatment of neurological and psychiatric disorders.

Neural pathways, also known as nerve tracts or fasciculi, refer to the highly organized and specialized routes through which nerve impulses travel within the nervous system. These pathways are formed by groups of neurons (nerve cells) that are connected in a series, creating a continuous communication network for electrical signals to transmit information between different regions of the brain, spinal cord, and peripheral nerves.

Neural pathways can be classified into two main types: sensory (afferent) and motor (efferent). Sensory neural pathways carry sensory information from various receptors in the body (such as those for touch, temperature, pain, and vision) to the brain for processing. Motor neural pathways, on the other hand, transmit signals from the brain to the muscles and glands, controlling movements and other effector functions.

The formation of these neural pathways is crucial for normal nervous system function, as it enables efficient communication between different parts of the body and allows for complex behaviors, cognitive processes, and adaptive responses to internal and external stimuli.

Agar is a substance derived from red algae, specifically from the genera Gelidium and Gracilaria. It is commonly used in microbiology as a solidifying agent for culture media. Agar forms a gel at relatively low temperatures (around 40-45°C) and remains stable at higher temperatures (up to 100°C), making it ideal for preparing various types of culture media.

In addition to its use in microbiology, agar is also used in other scientific research, food industry, and even in some artistic applications due to its unique gelling properties. It is important to note that although agar is often used in the preparation of food, it is not typically consumed as a standalone ingredient by humans or animals.

In the context of medical terminology, "solutions" refers to a homogeneous mixture of two or more substances, in which one substance (the solute) is uniformly distributed within another substance (the solvent). The solvent is typically the greater component of the solution and is capable of dissolving the solute.

Solutions can be classified based on the physical state of the solvent and solute. For instance, a solution in which both the solvent and solute are liquids is called a liquid solution or simply a solution. A solid solution is one where the solvent is a solid and the solute is either a gas, liquid, or solid. Similarly, a gas solution refers to a mixture where the solvent is a gas and the solute can be a gas, liquid, or solid.

In medical applications, solutions are often used as vehicles for administering medications, such as intravenous (IV) fluids, oral rehydration solutions, eye drops, and topical creams or ointments. The composition of these solutions is carefully controlled to ensure the appropriate concentration and delivery of the active ingredients.

Artificial membranes are synthetic or man-made materials that possess properties similar to natural biological membranes, such as selective permeability and barrier functions. These membranes can be designed to control the movement of molecules, ions, or cells across them, making them useful in various medical and biotechnological applications.

Examples of artificial membranes include:

1. Dialysis membranes: Used in hemodialysis for patients with renal failure, these semi-permeable membranes filter waste products and excess fluids from the blood while retaining essential proteins and cells.
2. Hemofiltration membranes: Utilized in extracorporeal circuits to remove larger molecules, such as cytokines or inflammatory mediators, from the blood during critical illnesses or sepsis.
3. Drug delivery systems: Artificial membranes can be used to encapsulate drugs, allowing for controlled release and targeted drug delivery in specific tissues or cells.
4. Tissue engineering: Synthetic membranes serve as scaffolds for cell growth and tissue regeneration, guiding the formation of new functional tissues.
5. Biosensors: Artificial membranes can be integrated into biosensing devices to selectively detect and quantify biomolecules, such as proteins or nucleic acids, in diagnostic applications.
6. Microfluidics: Artificial membranes are used in microfluidic systems for lab-on-a-chip applications, enabling the manipulation and analysis of small volumes of fluids for various medical and biological purposes.

Dextrans are a type of complex glucose polymers that are formed by the action of certain bacteria on sucrose. They are branched polysaccharides consisting of linear chains of α-1,6 linked D-glucopyranosyl units with occasional α-1,3 branches.

Dextrans have a wide range of applications in medicine and industry. In medicine, dextrans are used as plasma substitutes, volume expanders, and anticoagulants. They are also used as carriers for drugs and diagnostic agents, and in the manufacture of immunoadsorbents for the removal of toxins and pathogens from blood.

Dextrans can be derived from various bacterial sources, but the most common commercial source is Leuconostoc mesenteroides B-512(F) or L. dextranicum. The molecular weight of dextrans can vary widely, ranging from a few thousand to several million Daltons, depending on the method of preparation and purification.

Dextrans are generally biocompatible and non-toxic, but they can cause allergic reactions in some individuals. Therefore, their use as medical products requires careful monitoring and testing for safety and efficacy.

A lipid bilayer is a thin membrane made up of two layers of lipid molecules, primarily phospholipids. The hydrophilic (water-loving) heads of the lipids face outwards, coming into contact with watery environments on both sides, while the hydrophobic (water-fearing) tails point inward, away from the aqueous surroundings. This unique structure allows lipid bilayers to form a stable barrier that controls the movement of molecules and ions in and out of cells and organelles, thus playing a crucial role in maintaining cellular compartmentalization and homeostasis.

Three-dimensional (3D) imaging in medicine refers to the use of technologies and techniques that generate a 3D representation of internal body structures, organs, or tissues. This is achieved by acquiring and processing data from various imaging modalities such as X-ray computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, or confocal microscopy. The resulting 3D images offer a more detailed visualization of the anatomy and pathology compared to traditional 2D imaging techniques, allowing for improved diagnostic accuracy, surgical planning, and minimally invasive interventions.

In 3D imaging, specialized software is used to reconstruct the acquired data into a volumetric model, which can be manipulated and viewed from different angles and perspectives. This enables healthcare professionals to better understand complex anatomical relationships, detect abnormalities, assess disease progression, and monitor treatment response. Common applications of 3D imaging include neuroimaging, orthopedic surgery planning, cancer staging, dental and maxillofacial reconstruction, and interventional radiology procedures.

I'm sorry for any confusion, but the "Monte Carlo method" is actually a term from the field of mathematics and computer science, not medicine. It refers to a statistical technique that allows for the modeling of complex systems by running multiple simulations with random inputs. This method is widely used in various fields such as physics, engineering, and finance, but it is not a medical concept or term.

Skin absorption, also known as percutaneous absorption, refers to the process by which substances are taken up by the skin and pass into the systemic circulation. This occurs when a substance is applied topically to the skin and penetrates through the various layers of the epidermis and dermis until it reaches the capillaries, where it can be transported to other parts of the body.

The rate and extent of skin absorption depend on several factors, including the physicochemical properties of the substance (such as its molecular weight, lipophilicity, and charge), the concentration and formulation of the product, the site of application, and the integrity and condition of the skin.

Skin absorption is an important route of exposure for many chemicals, drugs, and cosmetic ingredients, and it can have both therapeutic and toxicological consequences. Therefore, understanding the mechanisms and factors that influence skin absorption is crucial for assessing the safety and efficacy of topical products and for developing strategies to enhance or reduce their absorption as needed.

Temperature, in a medical context, is a measure of the degree of hotness or coldness of a body or environment. It is usually measured using a thermometer and reported in degrees Celsius (°C), degrees Fahrenheit (°F), or kelvin (K). In the human body, normal core temperature ranges from about 36.5-37.5°C (97.7-99.5°F) when measured rectally, and can vary slightly depending on factors such as time of day, physical activity, and menstrual cycle. Elevated body temperature is a common sign of infection or inflammation, while abnormally low body temperature can indicate hypothermia or other medical conditions.

In the context of medical terminology, "motion" generally refers to the act or process of moving or changing position. It can also refer to the range of movement of a body part or joint. However, there is no single specific medical definition for the term "motion." The meaning may vary depending on the context in which it is used.

In medical terms, "gels" are semi-solid colloidal systems in which a solid phase is dispersed in a liquid medium. They have a viscous consistency and can be described as a cross between a solid and a liquid. The solid particles, called the gel network, absorb and swell with the liquid component, creating a system that has properties of both solids and liquids.

Gels are widely used in medical applications such as wound dressings, drug delivery systems, and tissue engineering due to their unique properties. They can provide a moist environment for wounds to heal, control the release of drugs over time, and mimic the mechanical properties of natural tissues.

Fluorescence microscopy is a type of microscopy that uses fluorescent dyes or proteins to highlight and visualize specific components within a sample. In this technique, the sample is illuminated with high-energy light, typically ultraviolet (UV) or blue light, which excites the fluorescent molecules causing them to emit lower-energy, longer-wavelength light, usually visible light in the form of various colors. This emitted light is then collected by the microscope and detected to produce an image.

Fluorescence microscopy has several advantages over traditional brightfield microscopy, including the ability to visualize specific structures or molecules within a complex sample, increased sensitivity, and the potential for quantitative analysis. It is widely used in various fields of biology and medicine, such as cell biology, neuroscience, and pathology, to study the structure, function, and interactions of cells and proteins.

There are several types of fluorescence microscopy techniques, including widefield fluorescence microscopy, confocal microscopy, two-photon microscopy, and total internal reflection fluorescence (TIRF) microscopy, each with its own strengths and limitations. These techniques can provide valuable insights into the behavior of cells and proteins in health and disease.

An artifact, in the context of medical terminology, refers to something that is created or introduced during a scientific procedure or examination that does not naturally occur in the patient or specimen being studied. Artifacts can take many forms and can be caused by various factors, including contamination, damage, degradation, or interference from equipment or external sources.

In medical imaging, for example, an artifact might appear as a distortion or anomaly on an X-ray, MRI, or CT scan that is not actually present in the patient's body. This can be caused by factors such as patient movement during the scan, metal implants or other foreign objects in the body, or issues with the imaging equipment itself.

Similarly, in laboratory testing, an artifact might refer to a substance or characteristic that is introduced into a sample during collection, storage, or analysis that can interfere with accurate results. This could include things like contamination from other samples, degradation of the sample over time, or interference from chemicals used in the testing process.

In general, artifacts are considered to be sources of error or uncertainty in medical research and diagnosis, and it is important to identify and account for them in order to ensure accurate and reliable results.

Biological transport, active is the process by which cells use energy to move materials across their membranes from an area of lower concentration to an area of higher concentration. This type of transport is facilitated by specialized proteins called transporters or pumps that are located in the cell membrane. These proteins undergo conformational changes to physically carry the molecules through the lipid bilayer of the membrane, often against their concentration gradient.

Active transport requires energy because it works against the natural tendency of molecules to move from an area of higher concentration to an area of lower concentration, a process known as diffusion. Cells obtain this energy in the form of ATP (adenosine triphosphate), which is produced through cellular respiration.

Examples of active transport include the uptake of glucose and amino acids into cells, as well as the secretion of hormones and neurotransmitters. The sodium-potassium pump, which helps maintain resting membrane potential in nerve and muscle cells, is a classic example of an active transporter.

Body water refers to the total amount of water present in the human body. It is an essential component of life and makes up about 60-70% of an adult's body weight. Body water is distributed throughout various fluid compartments within the body, including intracellular fluid (water inside cells), extracellular fluid (water outside cells), and transcellular fluid (water found in specific bodily spaces such as the digestive tract, eyes, and joints). Maintaining proper hydration and balance of body water is crucial for various physiological processes, including temperature regulation, nutrient transportation, waste elimination, and overall health.

The extracellular space is the region outside of cells within a tissue or organ, where various biological molecules and ions exist in a fluid medium. This space is filled with extracellular matrix (ECM), which includes proteins like collagen and elastin, glycoproteins, and proteoglycans that provide structural support and biochemical cues to surrounding cells. The ECM also contains various ions, nutrients, waste products, signaling molecules, and growth factors that play crucial roles in cell-cell communication, tissue homeostasis, and regulation of cell behavior. Additionally, the extracellular space includes the interstitial fluid, which is the fluid component of the ECM, and the lymphatic and vascular systems, through which cells exchange nutrients, waste products, and signaling molecules with the rest of the body. Overall, the extracellular space is a complex and dynamic microenvironment that plays essential roles in maintaining tissue structure, function, and homeostasis.

Fluorescein is not a medical condition or term, but rather a diagnostic dye used in various medical tests and procedures. Medically, it is referred to as Fluorescein Sodium, a fluorescent compound that absorbs light at one wavelength and emits light at another longer wavelength when excited.

In the field of ophthalmology (eye care), Fluorescein is commonly used in:

1. Fluorescein angiography: A diagnostic test to examine blood flow in the retina and choroid, often used to diagnose and manage conditions like diabetic retinopathy, age-related macular degeneration, and retinal vessel occlusions.
2. Tear film assessment: Fluorescein dye is used to evaluate the quality of tear film and diagnose dry eye syndrome by observing the staining pattern on the cornea.
3. Corneal abrasions/foreign body detection: Fluorescein dye can help identify corneal injuries, such as abrasions or foreign bodies, under a cobalt blue light.

In other medical fields, fluorescein is also used in procedures like:

1. Urinary tract imaging: To detect urinary tract abnormalities and evaluate kidney function.
2. Lymphangiography: A procedure to visualize the lymphatic system.
3. Surgical navigation: In some surgical procedures, fluorescein is used as a marker for better visualization of specific structures or areas.

Oxygen is a colorless, odorless, tasteless gas that constitutes about 21% of the earth's atmosphere. It is a crucial element for human and most living organisms as it is vital for respiration. Inhaled oxygen enters the lungs and binds to hemoglobin in red blood cells, which carries it to tissues throughout the body where it is used to convert nutrients into energy and carbon dioxide, a waste product that is exhaled.

Medically, supplemental oxygen therapy may be provided to patients with conditions such as chronic obstructive pulmonary disease (COPD), pneumonia, heart failure, or other medical conditions that impair the body's ability to extract sufficient oxygen from the air. Oxygen can be administered through various devices, including nasal cannulas, face masks, and ventilators.

Convection, in the context of medicine and physiology, refers to the movement of fluids or gases in a system due to differences in temperature or density. This process plays a crucial role in various biological systems, including blood circulation, heat regulation, and respiration.

For instance, in the human body, convection helps regulate body temperature through the movement of warm and cool blood between the core and peripheral tissues. In the lungs, air moves in and out of the alveoli through convective forces generated by the contraction and relaxation of the diaphragm and intercostal muscles during breathing.

In a broader medical context, convection may also refer to the movement of fluids or gases in medical devices such as intravenous (IV) lines, catheters, or respiratory equipment, where it can impact the distribution and delivery of medications, nutrients, or oxygen.

Fluorescein is not a medical condition, but rather a diagnostic dye that is used in various medical tests and procedures. It is a fluorescent compound that absorbs light at one wavelength and emits light at another wavelength, which makes it useful for imaging and detecting various conditions.

In ophthalmology, fluorescein is commonly used in eye examinations to evaluate the health of the cornea, conjunctiva, and anterior chamber of the eye. A fluorescein dye is applied to the surface of the eye, and then the eye is examined under a blue light. The dye highlights any damage or abnormalities on the surface of the eye, such as scratches, ulcers, or inflammation.

Fluorescein is also used in angiography, a medical imaging technique used to examine blood vessels in the body. A fluorescein dye is injected into a vein, and then a special camera takes pictures of the dye as it flows through the blood vessels. This can help doctors diagnose and monitor conditions such as cancer, diabetes, and macular degeneration.

Overall, fluorescein is a valuable diagnostic tool that helps medical professionals detect and monitor various conditions in the body.

Hydrogen-ion concentration, also known as pH, is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm (to the base 10) of the hydrogen ion activity in a solution. The standard unit of measurement is the pH unit. A pH of 7 is neutral, less than 7 is acidic, and greater than 7 is basic.

In medical terms, hydrogen-ion concentration is important for maintaining homeostasis within the body. For example, in the stomach, a high hydrogen-ion concentration (low pH) is necessary for the digestion of food. However, in other parts of the body such as blood, a high hydrogen-ion concentration can be harmful and lead to acidosis. Conversely, a low hydrogen-ion concentration (high pH) in the blood can lead to alkalosis. Both acidosis and alkalosis can have serious consequences on various organ systems if not corrected.

Membrane lipids are the main component of biological membranes, forming a lipid bilayer in which various cellular processes take place. These lipids include phospholipids, glycolipids, and cholesterol. Phospholipids are the most abundant type, consisting of a hydrophilic head (containing a phosphate group) and two hydrophobic tails (composed of fatty acid chains). Glycolipids contain a sugar group attached to the lipid molecule. Cholesterol helps regulate membrane fluidity and permeability. Together, these lipids create a selectively permeable barrier that separates cells from their environment and organelles within cells.

Statistical models are mathematical representations that describe the relationship between variables in a given dataset. They are used to analyze and interpret data in order to make predictions or test hypotheses about a population. In the context of medicine, statistical models can be used for various purposes such as:

1. Disease risk prediction: By analyzing demographic, clinical, and genetic data using statistical models, researchers can identify factors that contribute to an individual's risk of developing certain diseases. This information can then be used to develop personalized prevention strategies or early detection methods.

2. Clinical trial design and analysis: Statistical models are essential tools for designing and analyzing clinical trials. They help determine sample size, allocate participants to treatment groups, and assess the effectiveness and safety of interventions.

3. Epidemiological studies: Researchers use statistical models to investigate the distribution and determinants of health-related events in populations. This includes studying patterns of disease transmission, evaluating public health interventions, and estimating the burden of diseases.

4. Health services research: Statistical models are employed to analyze healthcare utilization, costs, and outcomes. This helps inform decisions about resource allocation, policy development, and quality improvement initiatives.

5. Biostatistics and bioinformatics: In these fields, statistical models are used to analyze large-scale molecular data (e.g., genomics, proteomics) to understand biological processes and identify potential therapeutic targets.

In summary, statistical models in medicine provide a framework for understanding complex relationships between variables and making informed decisions based on data-driven insights.

Leukoencephalopathies are a group of medical conditions that primarily affect the white matter of the brain, which consists mainly of nerve fibers covered by myelin sheaths. These conditions are characterized by abnormalities in the structure and function of the white matter, leading to various neurological symptoms such as cognitive decline, motor impairment, seizures, and behavioral changes.

The term "leukoencephalopathy" is derived from two Greek words: "leukos," meaning white, and "enkephalos," meaning brain. The suffix "-pathy" refers to a disease or suffering. Therefore, leukoencephalopathies refer specifically to diseases that affect the white matter of the brain.

There are various types of leukoencephalopathies, including genetic, metabolic, infectious, toxic, and immune-mediated forms. Some examples include multiple sclerosis, adrenoleukodystrophy, Alexander disease, Canavan disease, and Marchiafava-Bignami disease. The diagnosis of leukoencephalopathies typically involves a combination of clinical evaluation, imaging studies such as MRI, and sometimes genetic or laboratory testing to identify the underlying cause. Treatment depends on the specific type and severity of the condition and may include medications, dietary modifications, physical therapy, or supportive care.

The fornix, in the context of brain anatomy, is a bundle of nerve fibers that arises from the hippocampus, a major component of the limbic system associated with memory and spatial navigation. The fornix plays a crucial role in conveying information between different parts of the brain.

The fornix has two primary divisions: the precommissural fornix and the postcommissural fornix. The precommissural fornix contains fibers that originate from the hippocampus and the subiculum, while the postcommissural fornix consists of fibers that originate from the septal nuclei and other structures in the limbic system.

The two divisions of the fornix join together to form a structure called the body of the fornix, which then curves around the thalamus and continues as the crura (plural of crus) of the fornix. The crura split into two columns that pass through the interventricular foramen and terminate in the hypothalamus, specifically at the mammillary bodies.

The fornix is an essential structure for memory function, particularly episodic memory (memory of specific events or episodes). Damage to the fornix can result in various cognitive impairments, including memory loss and difficulties with spatial navigation.

Dimyristoylphosphatidylcholine (DMPC) is a type of phospholipid molecule that is commonly found in animal cell membranes. It is composed of two myristoyl fatty acid chains, a phosphate group, and a choline headgroup. DMPC has a gel-to-liquid crystalline phase transition temperature of around 23-25°C, which makes it a useful compound for studying the physical properties of lipid membranes and for creating model membrane systems in laboratory experiments.

Fluorescence is not a medical term per se, but it is widely used in the medical field, particularly in diagnostic tests, medical devices, and research. Fluorescence is a physical phenomenon where a substance absorbs light at a specific wavelength and then emits light at a longer wavelength. This process, often referred to as fluorescing, results in the emission of visible light that can be detected and measured.

In medical terms, fluorescence is used in various applications such as:

1. In-vivo imaging: Fluorescent dyes or probes are introduced into the body to highlight specific structures, cells, or molecules during imaging procedures. This technique can help doctors detect and diagnose diseases such as cancer, inflammation, or infection.
2. Microscopy: Fluorescence microscopy is a powerful tool for visualizing biological samples at the cellular and molecular level. By labeling specific proteins, nucleic acids, or other molecules with fluorescent dyes, researchers can observe their distribution, interactions, and dynamics within cells and tissues.
3. Surgical guidance: Fluorescence-guided surgery is a technique where surgeons use fluorescent markers to identify critical structures such as blood vessels, nerves, or tumors during surgical procedures. This helps ensure precise and safe surgical interventions.
4. Diagnostic tests: Fluorescence-based assays are used in various diagnostic tests to detect and quantify specific biomarkers or analytes. These assays can be performed using techniques such as enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), or flow cytometry.

In summary, fluorescence is a physical process where a substance absorbs and emits light at different wavelengths. In the medical field, this phenomenon is harnessed for various applications such as in-vivo imaging, microscopy, surgical guidance, and diagnostic tests.

Diffuse axonal injury (DAI) is a type of traumatic brain injury that occurs when there is extensive damage to the nerve fibers (axons) in the brain. It is often caused by rapid acceleration or deceleration forces, such as those experienced during motor vehicle accidents or falls. In DAI, the axons are stretched and damaged, leading to disruption of communication between different parts of the brain. This can result in a wide range of symptoms, including cognitive impairment, loss of consciousness, and motor dysfunction. DAI is often difficult to diagnose and can have long-term consequences, making it an important area of study in traumatic brain injury research.

Molecular conformation, also known as spatial arrangement or configuration, refers to the specific three-dimensional shape and orientation of atoms that make up a molecule. It describes the precise manner in which bonds between atoms are arranged around a molecular framework, taking into account factors such as bond lengths, bond angles, and torsional angles.

Conformational isomers, or conformers, are different spatial arrangements of the same molecule that can interconvert without breaking chemical bonds. These isomers may have varying energies, stability, and reactivity, which can significantly impact a molecule's biological activity and function. Understanding molecular conformation is crucial in fields such as drug design, where small changes in conformation can lead to substantial differences in how a drug interacts with its target.

Phosphatidylcholines (PtdCho) are a type of phospholipids that are essential components of cell membranes in living organisms. They are composed of a hydrophilic head group, which contains a choline moiety, and two hydrophobic fatty acid chains. Phosphatidylcholines are crucial for maintaining the structural integrity and function of cell membranes, and they also serve as important precursors for the synthesis of signaling molecules such as acetylcholine. They can be found in various tissues and biological fluids, including blood, and are abundant in foods such as soybeans, eggs, and meat. Phosphatidylcholines have been studied for their potential health benefits, including their role in maintaining healthy lipid metabolism and reducing the risk of cardiovascular disease.

In the context of medical terminology, "porosity" is not a term that is frequently used to describe human tissues or organs. However, in dermatology and cosmetics, porosity refers to the ability of the skin to absorb and retain moisture or topical treatments.

A skin with high porosity has larger pores and can absorb more products, while a skin with low porosity has smaller pores and may have difficulty absorbing products. It is important to note that this definition of porosity is not a medical one but is instead used in the beauty industry.

Confocal microscopy is a powerful imaging technique used in medical and biological research to obtain high-resolution, contrast-rich images of thick samples. This super-resolution technology provides detailed visualization of cellular structures and processes at various depths within a specimen.

In confocal microscopy, a laser beam focused through a pinhole illuminates a small spot within the sample. The emitted fluorescence or reflected light from this spot is then collected by a detector, passing through a second pinhole that ensures only light from the focal plane reaches the detector. This process eliminates out-of-focus light, resulting in sharp images with improved contrast compared to conventional widefield microscopy.

By scanning the laser beam across the sample in a raster pattern and collecting fluorescence at each point, confocal microscopy generates optical sections of the specimen. These sections can be combined to create three-dimensional reconstructions, allowing researchers to study cellular architecture and interactions within complex tissues.

Confocal microscopy has numerous applications in medical research, including studying protein localization, tracking intracellular dynamics, analyzing cell morphology, and investigating disease mechanisms at the cellular level. Additionally, it is widely used in clinical settings for diagnostic purposes, such as analyzing skin lesions or detecting pathogens in patient samples.

Fluorescein-5-isothiocyanate (FITC) is not a medical term per se, but a chemical compound commonly used in biomedical research and clinical diagnostics. Therefore, I will provide a general definition of this term:

Fluorescein-5-isothiocyanate (FITC) is a fluorescent dye with an absorption maximum at approximately 492-495 nm and an emission maximum at around 518-525 nm. It is widely used as a labeling reagent for various biological molecules, such as antibodies, proteins, and nucleic acids, to study their structure, function, and interactions in techniques like flow cytometry, immunofluorescence microscopy, and western blotting. The isothiocyanate group (-N=C=S) in the FITC molecule reacts with primary amines (-NH2) present in biological molecules to form a stable thiourea bond, enabling specific labeling of target molecules for detection and analysis.

In the context of medical and health sciences, particle size generally refers to the diameter or dimension of particles, which can be in the form of solid particles, droplets, or aerosols. These particles may include airborne pollutants, pharmaceutical drugs, or medical devices such as nanoparticles used in drug delivery systems.

Particle size is an important factor to consider in various medical applications because it can affect the behavior and interactions of particles with biological systems. For example, smaller particle sizes can lead to greater absorption and distribution throughout the body, while larger particle sizes may be filtered out by the body's natural defense mechanisms. Therefore, understanding particle size and its implications is crucial for optimizing the safety and efficacy of medical treatments and interventions.

I believe there may be some confusion in your question. "Rabbits" is a common name used to refer to the Lagomorpha species, particularly members of the family Leporidae. They are small mammals known for their long ears, strong legs, and quick reproduction.

However, if you're referring to "rabbits" in a medical context, there is a term called "rabbit syndrome," which is a rare movement disorder characterized by repetitive, involuntary movements of the fingers, resembling those of a rabbit chewing. It is also known as "finger-chewing chorea." This condition is usually associated with certain medications, particularly antipsychotics, and typically resolves when the medication is stopped or adjusted.

I'm sorry for any confusion, but "photochemistry" is not a term typically used in medical definitions. Photochemistry is a branch of chemistry that deals with the chemical effects of light. It involves the absorption of light by a substance, which can lead to the promotion of an electron to a higher energy state, and subsequently result in various chemical reactions.

In a medical context, photochemical processes might be discussed in relation to certain therapies or diagnostic techniques, such as photodynamic therapy for cancer treatment, where a photosensitizing agent is used that reacts with light to produce singlet oxygen or other reactive species to destroy nearby cells. However, it's not a term used to define a specific medical condition or concept in the same way that one might define "inflammation" or "metabolism."

Molecular models are three-dimensional representations of molecular structures that are used in the field of molecular biology and chemistry to visualize and understand the spatial arrangement of atoms and bonds within a molecule. These models can be physical or computer-generated and allow researchers to study the shape, size, and behavior of molecules, which is crucial for understanding their function and interactions with other molecules.

Physical molecular models are often made up of balls (representing atoms) connected by rods or sticks (representing bonds). These models can be constructed manually using materials such as plastic or wooden balls and rods, or they can be created using 3D printing technology.

Computer-generated molecular models, on the other hand, are created using specialized software that allows researchers to visualize and manipulate molecular structures in three dimensions. These models can be used to simulate molecular interactions, predict molecular behavior, and design new drugs or chemicals with specific properties. Overall, molecular models play a critical role in advancing our understanding of molecular structures and their functions.

A buffer in the context of physiology and medicine refers to a substance or system that helps to maintain stable or neutral conditions, particularly in relation to pH levels, within the body or biological fluids.

Buffers are weak acids or bases that can react with strong acids or bases to minimize changes in the pH level. They do this by taking up excess hydrogen ions (H+) when acidity increases or releasing hydrogen ions when alkalinity increases, thereby maintaining a relatively constant pH.

In the human body, some of the key buffer systems include:

1. Bicarbonate buffer system: This is the major buffer in blood and extracellular fluids. It consists of bicarbonate ions (HCO3-) and carbonic acid (H2CO3). When there is an increase in acidity, the bicarbonate ion accepts a hydrogen ion to form carbonic acid, which then dissociates into water and carbon dioxide. The carbon dioxide can be exhaled, helping to remove excess acid from the body.
2. Phosphate buffer system: This is primarily found within cells. It consists of dihydrogen phosphate (H2PO4-) and monohydrogen phosphate (HPO42-) ions. When there is an increase in alkalinity, the dihydrogen phosphate ion donates a hydrogen ion to form monohydrogen phosphate, helping to neutralize the excess base.
3. Protein buffer system: Proteins, particularly histidine-rich proteins, can also act as buffers due to the presence of ionizable groups on their surfaces. These groups can bind or release hydrogen ions in response to changes in pH, thus maintaining a stable environment within cells and organelles.

Maintaining appropriate pH levels is crucial for various biological processes, including enzyme function, cell membrane stability, and overall homeostasis. Buffers play a vital role in preserving these balanced conditions despite internal or external challenges that might disrupt them.

Brain edema is a medical condition characterized by the abnormal accumulation of fluid in the brain, leading to an increase in intracranial pressure. This can result from various causes, such as traumatic brain injury, stroke, infection, brain tumors, or inflammation. The swelling of the brain can compress vital structures, impair blood flow, and cause neurological symptoms, which may range from mild headaches to severe cognitive impairment, seizures, coma, or even death if not treated promptly and effectively.

A connectome is a comprehensive, detailed map of all the neural connections in a brain. It is a concept in neuroscience that involves mapping out and understanding the vast networks of neurons and their synaptic connections within the brain. The term "connectome" was first coined by Van Essen and Buckner in 2006.

The human connectome is an extremely complex network, with approximately 86 billion neurons and even more glial cells, all interconnected by trillions of synapses. Mapping the human connectome is a major scientific challenge that requires the integration of multiple techniques, including neuroimaging, neurophysiology, and computational modeling.

Understanding the connectome has important implications for understanding brain function and dysfunction, as well as for developing new treatments for neurological and psychiatric disorders.

Liposomes are artificially prepared, small, spherical vesicles composed of one or more lipid bilayers that enclose an aqueous compartment. They can encapsulate both hydrophilic and hydrophobic drugs, making them useful for drug delivery applications in the medical field. The lipid bilayer structure of liposomes is similar to that of biological membranes, which allows them to merge with and deliver their contents into cells. This property makes liposomes a valuable tool in delivering drugs directly to targeted sites within the body, improving drug efficacy while minimizing side effects.

Surface properties in the context of medical science refer to the characteristics and features of the outermost layer or surface of a biological material or structure, such as cells, tissues, organs, or medical devices. These properties can include physical attributes like roughness, smoothness, hydrophobicity or hydrophilicity, and electrical conductivity, as well as chemical properties like charge, reactivity, and composition.

In the field of biomaterials science, understanding surface properties is crucial for designing medical implants, devices, and drug delivery systems that can interact safely and effectively with biological tissues and fluids. Surface modifications, such as coatings or chemical treatments, can be used to alter surface properties and enhance biocompatibility, improve lubricity, reduce fouling, or promote specific cellular responses like adhesion, proliferation, or differentiation.

Similarly, in the field of cell biology, understanding surface properties is essential for studying cell-cell interactions, cell signaling, and cell behavior. Cells can sense and respond to changes in their environment, including variations in surface properties, which can influence cell shape, motility, and function. Therefore, characterizing and manipulating surface properties can provide valuable insights into the mechanisms of cellular processes and offer new strategies for developing therapies and treatments for various diseases.

'Escherichia coli' (E. coli) is a type of gram-negative, facultatively anaerobic, rod-shaped bacterium that commonly inhabits the intestinal tract of humans and warm-blooded animals. It is a member of the family Enterobacteriaceae and one of the most well-studied prokaryotic model organisms in molecular biology.

While most E. coli strains are harmless and even beneficial to their hosts, some serotypes can cause various forms of gastrointestinal and extraintestinal illnesses in humans and animals. These pathogenic strains possess virulence factors that enable them to colonize and damage host tissues, leading to diseases such as diarrhea, urinary tract infections, pneumonia, and sepsis.

E. coli is a versatile organism with remarkable genetic diversity, which allows it to adapt to various environmental niches. It can be found in water, soil, food, and various man-made environments, making it an essential indicator of fecal contamination and a common cause of foodborne illnesses. The study of E. coli has contributed significantly to our understanding of fundamental biological processes, including DNA replication, gene regulation, and protein synthesis.

Membrane proteins are a type of protein that are embedded in the lipid bilayer of biological membranes, such as the plasma membrane of cells or the inner membrane of mitochondria. These proteins play crucial roles in various cellular processes, including:

1. Cell-cell recognition and signaling
2. Transport of molecules across the membrane (selective permeability)
3. Enzymatic reactions at the membrane surface
4. Energy transduction and conversion
5. Mechanosensation and signal transduction

Membrane proteins can be classified into two main categories: integral membrane proteins, which are permanently associated with the lipid bilayer, and peripheral membrane proteins, which are temporarily or loosely attached to the membrane surface. Integral membrane proteins can further be divided into three subcategories based on their topology:

1. Transmembrane proteins, which span the entire width of the lipid bilayer with one or more alpha-helices or beta-barrels.
2. Lipid-anchored proteins, which are covalently attached to lipids in the membrane via a glycosylphosphatidylinositol (GPI) anchor or other lipid modifications.
3. Monotopic proteins, which are partially embedded in the membrane and have one or more domains exposed to either side of the bilayer.

Membrane proteins are essential for maintaining cellular homeostasis and are targets for various therapeutic interventions, including drug development and gene therapy. However, their structural complexity and hydrophobicity make them challenging to study using traditional biochemical methods, requiring specialized techniques such as X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy, and single-particle cryo-electron microscopy (cryo-EM).

Brain neoplasms, also known as brain tumors, are abnormal growths of cells within the brain. These growths can be benign (non-cancerous) or malignant (cancerous). Benign brain tumors typically grow slowly and do not spread to other parts of the body. However, they can still cause serious problems if they press on sensitive areas of the brain. Malignant brain tumors, on the other hand, are cancerous and can grow quickly, invading surrounding brain tissue and spreading to other parts of the brain or spinal cord.

Brain neoplasms can arise from various types of cells within the brain, including glial cells (which provide support and insulation for nerve cells), neurons (nerve cells that transmit signals in the brain), and meninges (the membranes that cover the brain and spinal cord). They can also result from the spread of cancer cells from other parts of the body, known as metastatic brain tumors.

Symptoms of brain neoplasms may vary depending on their size, location, and growth rate. Common symptoms include headaches, seizures, weakness or paralysis in the limbs, difficulty with balance and coordination, changes in speech or vision, confusion, memory loss, and changes in behavior or personality.

Treatment for brain neoplasms depends on several factors, including the type, size, location, and grade of the tumor, as well as the patient's age and overall health. Treatment options may include surgery, radiation therapy, chemotherapy, targeted therapy, or a combination of these approaches. Regular follow-up care is essential to monitor for recurrence and manage any long-term effects of treatment.

In the context of medicine, particularly in relation to cancer treatment, protons refer to positively charged subatomic particles found in the nucleus of an atom. Proton therapy, a type of radiation therapy, uses a beam of protons to target and destroy cancer cells with high precision, minimizing damage to surrounding healthy tissue. The concentrated dose of radiation is delivered directly to the tumor site, reducing side effects and improving quality of life during treatment.

Neurological models are simplified representations or simulations of various aspects of the nervous system, including its structure, function, and processes. These models can be theoretical, computational, or physical and are used to understand, explain, and predict neurological phenomena. They may focus on specific neurological diseases, disorders, or functions, such as memory, learning, or movement. The goal of these models is to provide insights into the complex workings of the nervous system that cannot be easily observed or understood through direct examination alone.

Cytoplasm is the material within a eukaryotic cell (a cell with a true nucleus) that lies between the nuclear membrane and the cell membrane. It is composed of an aqueous solution called cytosol, in which various organelles such as mitochondria, ribosomes, endoplasmic reticulum, Golgi apparatus, lysosomes, and vacuoles are suspended. Cytoplasm also contains a variety of dissolved nutrients, metabolites, ions, and enzymes that are involved in various cellular processes such as metabolism, signaling, and transport. It is where most of the cell's metabolic activities take place, and it plays a crucial role in maintaining the structure and function of the cell.

In medical terms, membranes refer to thin layers of tissue that cover or line various structures in the body. They are composed of connective tissue and epithelial cells, and they can be found lining the outer surface of the body, internal organs, blood vessels, and nerves. There are several types of membranes in the human body, including:

1. Serous Membranes: These membranes line the inside of body cavities and cover the organs contained within them. They produce a lubricating fluid that reduces friction between the organ and the cavity wall. Examples include the pleura (lungs), pericardium (heart), and peritoneum (abdominal cavity).
2. Mucous Membranes: These membranes line the respiratory, gastrointestinal, and genitourinary tracts, as well as the inner surface of the eyelids and the nasal passages. They produce mucus to trap particles, bacteria, and other substances, which helps protect the body from infection.
3. Synovial Membranes: These membranes line the joint cavities and produce synovial fluid, which lubricates the joints and allows for smooth movement.
4. Meninges: These are three layers of membranes that cover and protect the brain and spinal cord. They include the dura mater (outermost layer), arachnoid mater (middle layer), and pia mater (innermost layer).
5. Amniotic Membrane: This is a thin, transparent membrane that surrounds and protects the fetus during pregnancy. It produces amniotic fluid, which provides a cushion for the developing baby and helps regulate its temperature.

I'm sorry for any confusion, but "thermodynamics" is not a term that has a specific medical definition. It is a branch of physics that deals with the relationships between heat and other forms of energy. However, the principles of thermodynamics can be applied to biological systems, including those in the human body, such as in the study of metabolism or muscle function. But in a medical context, "thermodynamics" would not be a term used independently as a diagnosis, treatment, or any medical condition.

In the field of medical imaging, "phantoms" refer to physical objects that are specially designed and used for calibration, quality control, and evaluation of imaging systems. These phantoms contain materials with known properties, such as attenuation coefficients or spatial resolution, which allow for standardized measurement and comparison of imaging parameters across different machines and settings.

Imaging phantoms can take various forms depending on the modality of imaging. For example, in computed tomography (CT), a common type of phantom is the "water-equivalent phantom," which contains materials with similar X-ray attenuation properties as water. This allows for consistent measurement of CT dose and image quality. In magnetic resonance imaging (MRI), phantoms may contain materials with specific relaxation times or magnetic susceptibilities, enabling assessment of signal-to-noise ratio, spatial resolution, and other imaging parameters.

By using these standardized objects, healthcare professionals can ensure the accuracy, consistency, and reliability of medical images, ultimately contributing to improved patient care and safety.

the diffusion of the hydrodynamic velocity field Photon diffusion Plasma diffusion Random walk, model for diffusion Reverse ... If a diffusion process can be described by Fick's laws, it is called a normal diffusion (or Fickian diffusion); Otherwise, it ... Knudsen diffusion of gas in long pores with frequent wall collisions Lévy flight Molecular diffusion, diffusion of molecules ... self-diffusion). In this case, the elementary mean free path theory of diffusion gives for the diffusion coefficient D = 1 3 ℓ ...
... is the hypothesis that a sound change is an abrupt change that spreads gradually across the words in a ... Lexical diffusion represents a change in the phonemes in a word (substitution, metathesis, elision, epenthesis). It is abrupt ... Paul Kiparsky argues that under a proper definition of analogy as optimization, lexical diffusion is a non-proportional type of ... Wang accounted for such irregularities by positing a form of lexical diffusion: we hold that words change their pronunciations ...
The main difference between rotational diffusion and translational diffusion is that rotational diffusion has a periodicity of ... Diffusion equation Perrin friction factors Rotational correlation time False diffusion Conggang Li, Yaqiang Wang, and Gary J. ... If two eigenvalues of the diffusion tensor are equal, the particle diffuses as a spheroid with two unique diffusion rates and ... However at long times, t » t0 , the behaviour of rotational diffusion is different to translational diffusion: P ( θ , t ∣ θ 0 ...
... also refers to when water is forced from a region of lower concentration to high. It can occur in osmosis. v ... Reverse diffusion refers to a situation where the transport of particles (atoms or molecules) in a medium occurs towards ... t e (Articles lacking sources from December 2009, All articles lacking sources, Diffusion, All stub articles, Physics stubs). ... regions of higher concentration gradients, opposite to that observed during diffusion. This phenomenon occurs during phase ...
... has been used to study many structural problems in the past, ranging from domain sizes in polymers and disorder ... Spin diffusion is a process by which magnetization can be exchanged spontaneously between spins. The process is driven by ... Spin diffusion describes a situation wherein the individual nuclear spins undergo continuous exchange of energy. This permits ... EPS2:Spin-Diffusion v t e (Articles with short description, Short description matches Wikidata, Wikipedia articles needing ...
Direct diffusion was common in ancient times when small groups of humans lived in adjoining settlements. Indirect diffusion is ... While the concept of diffusion is well accepted in general, conjectures about the existence or the extent of diffusion in some ... It is distinct from the diffusion of innovations within a specific culture. Examples of diffusion include the spread of the war ... Five major types of cultural diffusion have been defined: Expansion diffusion: an innovation or idea that develops in a source ...
Official website Diffusion Facebook Diffusion MySpace v t e (Use dmy dates from April 2022, Articles lacking sources from March ... Diffusion Pictures is a distributor of feature films in the United Kingdom. Formed in late 2006, its first two releases, Funny ... Diffusion then released Reprise by Norwegian director, Joachim Trier and Lars von Trier's film, The Boss of It All. The ...
While diffusion hardening is performed mainly on steel parts and carbon is mainly the element used for diffusion, diffusion ... Diffusion hardening is a process used in manufacturing that increases the hardness of steels. In diffusion hardening, diffusion ... Besides metals and diffusion elements used, diffusion hardening processes differ in the temperature required for diffusion, the ... All these things must come into consideration when choosing a diffusion hardening process. case-hardening "Diffusion Treatment ...
... can be in the same or opposite direction of a drift current. The diffusion current and drift current together ... Diffusion current is a current in a semiconductor caused by the diffusion of charge carriers (electrons and/or electron holes ... In a region where n and p vary with distance, a diffusion current is superimposed on that due to conductivity. This diffusion ... This current is called the diffusion current. The drift current and the diffusion current make up the total current in the ...
... is typically greater than classical diffusion. The fact that classical diffusion and Bohm diffusion scale as ... "Bohm diffusion". Physics portal Classical diffusion Hsu diffusion Plasma diffusion Bohm, D. (1949) The characteristics of ... studying these machines has led to the neoclassical diffusion concept. Bohm diffusion is characterized by a diffusion ... The diffusion of plasma across a magnetic field was conjectured to follow the Bohm diffusion scaling as indicated from the ...
A diffusion line (also known as a bridge line) is a secondary line of merchandise created by a high-end fashion house or ... Diffusion products may be on sale alongside designers' signature line but they can also be made available at concession outlets ... The use of a diffusion line is a part of the strategy of massification where luxury brands attempt to reach a broader market in ... Diffusion lines serve several purposes for designers. They can substantially increase sales volumes as their products become ...
The Diffusion Inhibitor is the first known attempt to build a working fusion power device. It was designed and built at the ... To disguise the actual purpose from NACA leadership, they called it the "Diffusion Inhibitor". Lewis agreed to provide $5,000 ( ...
The motion of magnetic fields is described by the magnetic diffusion equation and is due primarily to induction and diffusion ... Magnetic diffusion refers to the motion of magnetic fields, typically in the presence of a conducting solid or fluid such as a ... Also, different diffusion time equations can be derived for nonlinear saturable materials such as steel. Holt, E. H.; Haskell, ... The magnetic diffusion equation is ∂ B → ∂ t = ∇ × [ v → × B → ] + 1 μ 0 σ ∇ 2 B → {\displaystyle {\frac {\partial {\vec {B ...
Unlike typical diffusion, anomalous diffusion is described by a power law, ⟨ r 2 ( τ ) ⟩ = K α τ α {\displaystyle \langle r^{2 ... Anomalous diffusion is a diffusion process with a non-linear relationship between the mean squared displacement (MSD), ⟨ r 2 ( ... Fractional diffusion equations were introduced in order to characterize anomalous diffusion phenomena. Recently, anomalous ... It has been found that equations describing normal diffusion are not capable of characterizing some complex diffusion processes ...
Physics portal Bohm diffusion Classical diffusion Hsu diffusion Hsu, Jang-Yu; Wu, Kaibang; Kumar Agarwal, Sujeet; Ryu, Chang-Mo ... Plasma diffusion across a magnetic field is an important topic in magnetic confinement of fusion plasma. It especially concerns ... Hsu diffusion predicts 1/B3/2 scaling, which is presumably the best confinement scenario in magnetized plasma. ... v t e (Articles with short description, Short description matches Wikidata, Diffusion, Plasma physics, All stub articles, ...
... (ambipolar: relating to or consisting of both electrons and positive ions moving in opposite directions) is ... In astrophysics, "ambipolar diffusion" refers specifically to the decoupling of neutral particles from plasma, for example in ... In plasma physics, ambipolar diffusion is closely related to the concept of quasineutrality. In most plasmas, the forces acting ... "Definition of AMBIPOLAR". Kizilyalli, M.; Corish, J.; Metselaar, R. (1999). "Definitions of terms for diffusion in the solid ...
Diffusion, in architectural acoustics, is the spreading of sound energy evenly in a given environment. A perfectly diffusive ... Diffusors can aid sound diffusion, but this is not why they are used in many cases; they are more often used to remove ... The new goal was to find a new surface geometry that would combine the excellent diffusion characteristics of MLS designs with ... "The effects of 2d diffusers on sound diffusion". PF. (in Dari) T. J. Cox and P. D'Antonio, Acoustic Absorbers and Diffusors - ...
Contrary to its name, a diffusion flame involves both diffusion and convection processes. The name diffusion flame was first ... A nearly-turbulent diffusion flame A candle in a microgravity environment. This is a rare example of a diffusion flame which ... Diffusion flames tend to have a less-localized flame front than premixed flames.[citation needed] The contexts for diffusion ... The burning rate is however still limited by the rate of diffusion. Diffusion flames tend to burn slower and to produce more ...
... is typically used in video games, when multiple agents must path towards a single target agent. For ... Collaborative Diffusion is a type of pathfinding algorithm which uses the concept of antiobjects, objects within a computer ... Collaborative Diffusion is favored for its efficiency over other pathfinding algorithms, such as A*, when handling multiple ... "Collaborative Diffusion: Programming Antiobjects" (PDF). AgentSheets Inc & University of Colorado. Retrieved 25 July 2015. v t ...
Fickian diffusion theory and further advancements in research on atmospheric diffusion can be applied to model the effects that ... Diffusion flame Fick's laws of diffusion Planar laser-induced fluorescence Particle image velocimetry False diffusion Hideto ... and molecular diffusion results in the following differential equation considering only the turbulent diffusion approximation ... Turbulent diffusion is the transport of mass, heat, or momentum within a system due to random and chaotic time dependent ...
... , as opposed to trans-cultural diffusion, is a demographic term referring to a migratory model, developed by ... That is referred to as the Neolithic demic diffusion model. Craniometric and archaeological studies have also arrived at the ... Y genetic data support the Neolithic demic diffusion model. Proc. Natl. Acad. Sci. 99(17): 11008-11013. C. Loring Brace, Noriko ... Estimating the Impact of Prehistoric Admixture on the Genome of Europeans, Dupanloup et al., 2004 Origin, Diffusion, and ...
... (sometimes referred to simply as 'diffusion') is a performance practice in the field of acousmatic music. ... It is up to the diffusion engineer to perform the piece in such a way that the musical content is adequately interpreted as ... In many cases, the sound diffusion is performed by the composer themselves, whose task it is to integrate and interpret the ... Modern diffusion practice also tries to articulate musical material by playing different passages through different sounding ...
This numerical effect takes the form of an extra high diffusion rate. When numerical diffusion applies to the components of the ... Numerical diffusion is a difficulty with computer simulations of continua (such as fluids) wherein the simulated medium ... A simple way to avoid the difficulty is to add diffusion that smooths out the shock or current sheet. Higher order numerical ... As an example of numerical diffusion, consider an Eulerian simulation using an explicit time-advance of a drop of green dye ...
... most commonly refers to the diffusion, or spread of momentum between particles (atoms or molecules) of ... Understanding the exact nature of diffusion is a key aspect towards understanding momentum diffusion due to pressure. A fluid ... "momentum diffusion" can also refer to the diffusion of the probability for a single particle to have a particular momentum. In ... Momentum diffusion can be attributed to either external pressure or shear stress or both. When pressure is applied on an ...
The problem of diffusion in the atmosphere is often reduced to that of solving the original gradient based diffusion equation ... Statistical diffusion theory originated with G. I. Taylor's (1921) paper titled "Diffusion by continuous movements" and later ... In turbulent flows, on top of mixing by molecular diffusion, eddies stir (Eddy diffusion § Note on stirring and mixing) the ... In fluid dynamics, eddy diffusion, eddy dispersion, or turbulent diffusion is a process by which fluid substances mix together ...
... where the charge transport was via the diffusion mechanism. See Fick's laws of diffusion. To implement this notion ... Diffusion Capacitance is the capacitance that happens due to transport of charge carriers between two terminals of a device, ... The change in the amount of transiting charge divided by the change in the voltage causing it is the diffusion capacitance. The ... the corresponding diffusion capacitance: C d i f f {\displaystyle C_{diff}} . is C d i f f = d Q d V = d I ( V ) d V τ F {\ ...
By running the diffusion with an edge seeking diffusion coefficient for a certain number of iterations, the image can be ... This diffusion process is a linear and space-invariant transformation of the original image. Anisotropic diffusion is a ... Anisotropic diffusion can be used to remove noise from digital images without blurring edges. With a constant diffusion ... Anisotropic diffusion is normally implemented by means of an approximation of the generalized diffusion equation: each new ...
... uses a kind of diffusion model (DM), called a latent diffusion model (LDM) developed by the CompVis group at ... Wikimedia Commons has media related to Stable Diffusion. Stable Diffusion Demo Interactive Explanation of Stable Diffusion "We ... Stable Diffusion is a deep learning, text-to-image model released in 2022 based on diffusion techniques. It is primarily used ... Stable Diffusion is a latent diffusion model, a kind of deep generative artificial neural network. Its code and model weights ...
... is very popular in Algeria and is also well known in many other countries including Morocco, Tunisia and France ... Gnawa Diffusion started their career in 1993 with the release of the album Légitime différence. Members of the band: Amazigh ... Gnawa Diffusion is an Algerian Gnawa music band based in Grenoble, France. The group's lead singer, Amazigh (literally meaning ...
In general, surface diffusion occurs much faster than grain boundary diffusion, and grain boundary diffusion occurs much faster ... In substitutional lattice diffusion (self-diffusion for example), the atom can only move by substituting place with another ... Atomic diffusion in polycrystalline materials is therefore often modeled using an effective diffusion coefficient, which is a ... In chemical physics, atomic diffusion is a diffusion process whereby the random, thermally-activated movement of atoms in a ...
the diffusion of the hydrodynamic velocity field Photon diffusion Plasma diffusion Random walk, model for diffusion Reverse ... If a diffusion process can be described by Ficks laws, it is called a normal diffusion (or Fickian diffusion); Otherwise, it ... Knudsen diffusion of gas in long pores with frequent wall collisions Lévy flight Molecular diffusion, diffusion of molecules ... self-diffusion). In this case, the elementary mean free path theory of diffusion gives for the diffusion coefficient D = 1 3 ℓ ...
A diffusion test is a type of pulmonary function test to measure gas transfer from the lungs into the bloodstream. Learn about ... What is a Diffusion Test?. The Division of Pulmonary Medicine at Cincinnati Childrens performs diffusion tests. ... Diffusion is measured by having your child place padded nose clips on his or her nose and placing their mouth around a single ... Diffusion tests measure gas transfer from the lungs into the bloodstream. Various diseases can cause changes in the lungs and ...
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Public Comments on Paducah Gaseous Diffusion Plant Documents. How to Submit Comments. Comments on Paducah Gaseous Diffusion ... Advisory Board and NIOSH Discussions on Paducah Gaseous Diffusion Plant. The Paducah Gaseous Diffusion Plant discussion papers ... Draft: Paducah Gaseous Diffusion Plant Site Profile Review [4 MB (154 pages)]. Contract No. 200-2004-03805. Task Order No. 1. ... Paducah Gaseous Diffusion Plant, and Portsmouth Gaseous Diffusion Plant ...
The Stable Diffusion Concepts Library is an open-source library developed by a team of experts in the field of diffusion ... In conclusion, the Stable Diffusion Concepts Library is a remarkable tool for anyone working with diffusion processes. Its ... Another key feature of the Stable Diffusion Concepts Library is its robust implementation of numerical algorithms. Diffusion ... as well as more advanced models like fractional diffusion models. No matter what type of diffusion process you are dealing with ...
Title:LafitE: Latent Diffusion Model with Feature Editing for Unsupervised Multi-class Anomaly Detection. Authors:Haonan Yin, ... We then introduce a feature editing strategy that modifies the input feature space of the diffusion model to further alleviate ... View a PDF of the paper titled LafitE: Latent Diffusion Model with Feature Editing for Unsupervised Multi-class Anomaly ... Extensive experiments on benchmark datasets MVTec-AD and MPDD show that the proposed LafitE, \ie, Latent Diffusion Model with ...
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This paper is concerned with a nonlocal nonlinear diffusion equation with Dirichlet boundary condition and a source ,svg style ... This paper is concerned with a nonlocal nonlinear diffusion equation with Dirichlet boundary condition and a source , , , , , ... Since the long-range effects are taken into account, nonlocal diffusion equations of the form have been widely used to model ... Another classical equation that has been used to model diffusion is the well-known porous medium equation with . This equation ...
Diffusion Residency - Alex Murdoch. November 27, 2008 by Giles Lane Alex Murdoch, founder and director of Cartoon de Salvo, one ... community illustration future jobs fund eBooks diffusion film alice angus publishing on demand process research creative ... Over 50 shows and stories were created, which are being collated and illustrated by Alex as part of her Diffusion Residency. ...
Requires Stable Diffusion AI with ControlNet OpenPose extension.. ** For Windows 10+.. How does it work? Watch the full video ... For those who wish to install Stable Diffusion AI with the Automatic1111 webUI, here is the BEST GUIDE ON YOUTUBE, which also ... Those will be created in Stable Diffusion using a text prompt, so the limit is your imagination! Its like having an infinite ... Check the folder "stable-diffusion-webui\extensions\sd-webui-controlnet" and see it the folder is there, and that it is not ...
... dc.contributor.author. Wong, Kai-Wai. ... Magnetic flux diffusion through HTS shields. IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY. June 1998. 8(2): 62-68.. ... It is shown that this logarithmic time dependence is a result of flux line diffusion between superconducting grains rather than ...
This open access book analyses the global diffusion of social policy as a process driven by multiplex ties between countries in ... Networks are viewed as the structural backbone of the diffusion process, and diffusion is anlaysed via several subfields of ... The Global Diffusion of Work-Injury Insurance: The Role of Spatial Networks and Nation Building *Nate Breznau, Felix Lanver ... The focus is on a global perspective of social policy diffusion via networks, and it is the first book to explicitly follow ...
These MPNNs are then used in generative models based on a probabilistic diffusion process, which is found to produce ... Equivariant Message-Passing Neural Networks and Probabilistic Diffusion Models for Materials Science. ...
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This paper investigates the effects of social network structure on the diffusion of agricultural technologies using household- ... Diffusion of Innovation eJournal. Subscribe to this fee journal for more curated articles on this topic ... We find that the diffusion of information on a complex technology is not promoted by simply knowing an extension agent but by ... Todo, Yasuyuki and Matous, Petr and Mojo, Dagne, Effects of Social Network Structure on the Diffusion and Adoption of ...
Round Digital Diffusion/FX 1/4 Filter W412DDFX14 at Filmtools ... Tiffen 4.5" Digital Diffusion/FX Filters for densities: 1/4, 1/ ... The Digital Diffusion/FX filter is the filter of choice for making people look great without evidence of filtration. These ... filters are similar to the Tiffen Black Diffusion/FX without the internal dot pattern. - Made of solid Water White (WW) glass ...
Diffusion-weighted imaging (DWI) is a well-established magnetic resonance imaging (MRI) method for diagnosing cerebral ischemia ... states and abnormal conditions are easily interpreted through the use of DWI in conjunction with the use of apparent diffusion ... Imaging and interpretation of water diffusion have improved with the development of diffusion tensor imaging (DTI). Diffusion ... Tensor and Diffusion Ellipsoid. On DWI commonly used to diagnose acute stroke (see the image below), diffusion is described by ...
In comparison to traditional diffusion indices, which focus on intra-voxel diffusion properties, heterogeneity captures the ... In comparison to traditional diffusion indices, which focus on intra-voxel diffusion properties, heterogeneity captures the ... Diffusion tensor imaging (DTI) allows to investigate the microstructure of brain tissue. It measures the magnitude and ... Diffusion tensor imaging (DTI) allows to investigate the microstructure of brain tissue. It measures the magnitude and ...
This KipperTie Diffusion OLPF for RED DSMC2 S35 - Carbon 1 softens fine detail and retains sharp focus with minimal contrast ... The KipperTie Diffusion OLPF for RED DSMC2 S35 - Carbon 1 softens fine detail and retains sharp focus with minimal contrast ... The KipperTie lowcon diffusion filter range is carefully designed to provide the most effective, beautiful and consistent ... Greatly reduced sparkling and bokeh patterning, with micro-fine diffusion particles. IMPORTANT NOTE: Dragon and Helium ...
Diffusion models have experienced a surge of interest as highly expressive yet efficiently trainable probabilistic models. We ... Listen, Denoise, Action! Audio-Driven Motion Synthesis with Diffusion Models. Alexanderson, Simon KTH, School of Electrical ... Finally, we generalise the guidance procedure to obtain product-of-expert ensembles of diffusion models and demonstrate how ... conformers, dance, diffusion models, ensemble models, generative models, gestures, guided interpolation, locomotion, machine ...
Hypoxic-ischemic changes in brain are detected earlier with diffusion-weighted (DW) than with T2-weighted magnetic resonance ( ... Diffusion- and T2-weighted increases in magnetic resonance images of immature brain during hypoxia-ischemia: transient reversal ... Hypoxic-ischemic changes in brain are detected earlier with diffusion-weighted (DW) than with T2-weighted magnetic resonance ( ... early hypoxic-ischemic injury in immature brain is detected as an increase in intensity in both diffusion- and T2-weighted ...
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US-5415969-A chemical patent summary.
Comparison study on LES combustion models in diffusion flame. *Mark. Liu, Xiao LU ; Gong, Cheng LU ; Li, Zhiming and Zheng, ... Diffusion flame, FPV model, Gas turbine, Large-Eddy Simulation, PaSR model, PDF model. in Harbin Gongcheng Daxue Xuebao/Journal ... Diffusion flame; FPV model; Gas turbine; Large-Eddy Simulation; PaSR model; PDF model}}, language = {{chi}}, month = {{03}}, ... Comparison study on LES combustion models in diffusion flame}}, url = {{http://dx.doi.org/10.11990/jheu.201705045}}, doi = {{ ...
A High Order Finite Difference Discretization Strategy Based on Extrapolation for Convection Diffusion Equations. Numerical ... A Second Order Characteristic Mixed Finite Element Method for Convection Diffusion Reaction Equations ... A High Order Finite Difference Discretization Strategy Based on Extrapolation for Convection Diffusion Equations. Numerical ...
... In an effort to resolve the problem of whether a certain soil will support a ... TRT Terms: Boundary value problems; Diffusion (Optics); Equilibrium (Mechanics); Graphics; Heat transfer; Humidity; Properties ... A comparison of the experimental and calculated diagrams shows the analogy between heat transfer and diffusion to the quite ... given vehicle under specific weather conditions, preliminary diffusion rate studies in artificial soils were conducted which ...
  • [ 1 , 2 ] Imaging and interpretation of water diffusion have improved with the development of diffusion tensor imaging (DTI). (medscape.com)
  • Diffusion tensor imaging has shown strong momentum in research performed to evaluate the neural fibers of the central nervous system (CNS). (medscape.com)
  • Diffusion tensor imaging can be used to measure anisotropy per voxel and provides directional information relevant for magnetic resonance tractography or fiber tracking in vivo. (medscape.com)
  • Diffusion tensor imaging allows direct examination of the brain microstructure and has become a useful tool for investigating brain disorders such as stroke, epilepsy, multiple sclerosis (MS), brain tumors, and demyelinating and dysmyelinating disorders. (medscape.com)
  • This paper1 describes image processing techniques for Diffusion Tensor Magnetic Resonance. (sciweavers.org)
  • In Diffusion Tensor MRI, a tensor describing local water diffusion is acquired for each voxel. (sciweavers.org)
  • We present a decomposition of the diffusion tensor based on its symmetry properties resulting in useful measures describing the geometry of the diffusion ellipsoid. (sciweavers.org)
  • We show how filtering of the tensor data of a human brain can provide a description of macrostructural diffusion which can be used for meas. (sciweavers.org)
  • We discuss how such encoding enables the extension of the well-known scalar b-value to a tensor-valued entity we call the diffusion measurement tensor. (lu.se)
  • As an example analysis, we use this new information to estimate a Gaussian distribution over diffusion tensors in each voxel, described by its mean (a diffusion tensor) and its. (lu.se)
  • Diffusion tensor distribution imaging of an in vivo mouse brain at ultra-high magnetic field by spatiotemporal encoding. (lu.se)
  • Diffusion tensor distribution imaging. (lu.se)
  • The geometric nature of the diffusion tensors can quantitatively characterize the local structure in tissues such as bone, muscles, and white matter of the brain. (sciweavers.org)
  • Multidimensional correlation of nuclear relaxation rates and diffusion tensors for model-free investigations of heterogeneous anisotropic porous materials. (lu.se)
  • Recently, I discovered an impressive library known as the Stable Diffusion Concepts Library, which has significantly transformed my strategy for managing diffusion processes. (vectorlinux.com)
  • The Stable Diffusion Concepts Library is an open-source library developed by a team of experts in the field of diffusion processes. (vectorlinux.com)
  • Another key feature of the Stable Diffusion Concepts Library is its robust implementation of numerical algorithms. (vectorlinux.com)
  • Speaking of documentation, the Stable Diffusion Concepts Library excels in this aspect as well. (vectorlinux.com)
  • In conclusion, the Stable Diffusion Concepts Library is a remarkable tool for anyone working with diffusion processes. (vectorlinux.com)
  • I highly recommend giving it a try and experiencing the power of stable diffusion modeling firsthand. (vectorlinux.com)
  • The Stable Diffusion Concepts Library is an exceptional open-source library that simplifies the modeling and analysis of diffusion processes. (vectorlinux.com)
  • Andy Baio and Simon Willison made a tool to browse a subset of this data behind the recently released Stable Diffusion. (flowingdata.com)
  • Ever wanted to use Poser to setup your AI image generation, using any Poser human figure to establish the pose, body proportions and camera framing, and then exporting a preprocessed OpenPose-compatible pose directly to Stable Diffusion? (renderosity.com)
  • It's like creating the scene in Poser, and using Stable Diffusion as a rendering engine! (renderosity.com)
  • Those will be created in Stable Diffusion using a text prompt, so the limit is your imagination! (renderosity.com)
  • Requires Stable Diffusion AI with ControlNet OpenPose extension. (renderosity.com)
  • Computing and visualising intra-voxel orientation-specific relaxation-diffusion features in the human brain. (lu.se)
  • The diffusion ellipsoid defines the magnitude and direction of the diffusion of water molecules in each voxel in the brain. (medscape.com)
  • The eigenvector corresponding to the largest eigenvalue, termed the principal eigenvector, defines the main direction of diffusion of water molecules in that voxel (see the image below). (medscape.com)
  • normal states and abnormal conditions are easily interpreted through the use of DWI in conjunction with apparent diffusion coefficient (ADC) imaging by correlating findings of hyperintensity on DWI images with findings of hypointensity on ADC images (see the images below). (medscape.com)
  • On DWI commonly used to diagnose acute stroke (see the image below), diffusion is described by using the apparent diffusion coefficient (ADC). (medscape.com)
  • The close relationship between local image structure and apparent diffusion makes this image modality very interesting for medical image analysis. (sciweavers.org)
  • MRI diffusion studies have been shown to help differentiate Wilms tumor from neuroblastoma, with the apparent diffusion coefficient (ADC) being substantially higher for Wilms tumor. (medscape.com)
  • The diffusion capacity of the lung for carbon monoxide (DLCO) is used to measure the body's ability to transfer oxygen across the alveolar-capillary membrane. (medscape.com)
  • Multidimensional diffusion magnetic resonance imaging for characterization of tissue microstructure in breast cancer patients: A prospective pilot study. (lu.se)
  • This paper provides an approach to characterize the photoacid diffusion length in a laboratory setting by applying a bilayer stack technique. (nist.gov)
  • Diffusion in structured tissue such as white matter is anisotropic. (medscape.com)
  • Multidimensional encoding of restricted and anisotropic diffusion by double rotation of the q vector. (lu.se)
  • DTI allows clinicians to look at anisotropic diffusion in white-matter tracts, but it is limited in its ability to demonstrate spatial and directional anisotropy. (medscape.com)
  • Towards non-parametric diffusion-T1 characterization of crossing fibers in the human brain. (lu.se)
  • When talking about the extent of diffusion, two length scales are used in two different scenarios: Brownian motion of an impulsive point source (for example, one single spray of perfume)-the square root of the mean squared displacement from this point. (wikipedia.org)
  • Diffusion, or brownian movement, denotes the random motion of molecules. (medscape.com)
  • This paper extends the experimental work to provide photoresist metrics, based upon the measured kinetics parameters and the diffusion length, that next-generation resist must meet for sub-22 nm CD. (nist.gov)
  • In upcoming clinical trials, Ross hopes to compare traditional outcome measurements with functional diffusion mapping analyses and actual patients' survival. (diagnosticimaging.com)
  • This open access book analyses the global diffusion of social policy as a process driven by multiplex ties between countries in global social networks. (springer.com)
  • Diffusion-weighted imaging (DWI) is a well-established magnetic resonance imaging (MRI) method for diagnosing cerebral ischemia. (medscape.com)
  • article{osti_1712830, title = {Concentration Dependence of Diffusion-Limited Reaction Rates and Its Consequences}, author = {Sarkar, Sumantra}, abstractNote = {}, doi = {10.1103/PhysRevX.10.041032}, journal = {Physical Review. (osti.gov)
  • It is shown that this logarithmic time dependence is a result of flux line diffusion between superconducting grains rather than fluxoid avalanches or flux bundle creep. (ku.edu)
  • It provides a comprehensive set of tools and algorithms to model and analyze diffusion phenomena in a stable and reliable manner. (vectorlinux.com)
  • With its wide range of diffusion models, robust numerical algorithms, intuitive API, and comprehensive documentation, it is a valuable tool for anyone working in this field. (vectorlinux.com)
  • Accuracy and precision of statistical descriptors obtained from multidimensional diffusion signal inversion algorithms. (lu.se)
  • Effects of imaging gradients in sequences with varying longitudinal storage time - case of diffusion exchange imaging. (lu.se)
  • Diffusion-weighted imaging has been shown to be useful in the investigation of brain disorders such as epilepsy , multiple sclerosis , brain abscesses , brain tumors, mild traumatic brain injury, and hypertensive encephalopathy (see the images below). (medscape.com)
  • Axial fluid-attenuated inversion recovery (FLAIR) image (top left), diffusion-weighted image (DWI) (top right), and axial and sagittal T1-weighted (T1W) images (bottom) in a 40-year-old man with a history of intravenous drug abuse and fever demonstrate multiple enhancing focal brain lesions in the gray-white matter junction (arrow) compatible with septic emboli. (medscape.com)
  • The UM researchers have shown that functional diffusion mapping can identify brain tumor patients who are responding to chemotherapy or radiation after only three weeks of treatment, more than two months earlier than traditional tests. (diagnosticimaging.com)
  • Diffusion-weighted MRS (dMRS) gives access to diffusion properties of endogenous intracellular brain metabolites that are preferentially located inside specific brain cell populations. (lu.se)
  • The new measurements contain information about higher order diffusion propagator covariances not present in sPFG. (lu.se)
  • Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. (wikipedia.org)
  • By measuring the self-diffusion of molecules in biological tissues, we obtain information about microscopic structures that are too small to resolve in conventional images. (lu.se)
  • We first explore the generative-based approach and investigate latent diffusion models for reconstruction to mitigate the notorious ``identity shortcut'' issue in auto-encoder based methods. (arxiv.org)
  • Extensive experiments on benchmark datasets MVTec-AD and MPDD show that the proposed LafitE, \ie, Latent Diffusion Model with Feature Editing, outperforms state-of-art methods by a significant margin in terms of average AUROC. (arxiv.org)
  • Diffusion is a stochastic process due to the inherent randomness of the diffusing entity and can be used to model many real-life stochastic scenarios. (wikipedia.org)
  • An example of a process where both bulk motion and diffusion occur is human breathing. (wikipedia.org)
  • Second, there is a "diffusion" process. (wikipedia.org)
  • Proceedings of SPIE, 6923, 692317(2008)), the measured diffusion length was predicted providing a rapid materials screening process conditions towards improved CD and LER optimization. (nist.gov)
  • No matter what type of diffusion process you are dealing with, you can find a suitable model to accurately represent it. (vectorlinux.com)
  • First, "institutions" themselves (defined as "going concerns" where the collective action controls member actions), carry novel principles and evolve through their diffusion process. (openedition.org)
  • Networks are viewed as the structural backbone of the diffusion process, and diffusion is anlaysed via several subfields of social policy, in order to interrogate which network dimensions drive this process. (springer.com)
  • The collection tests the network structures in terms of their relevance to the diffusion process in different subfields of social policy such as old age and survivor pensions, labor and labor markets, health and long-term care, education and training, and family and gender policy. (springer.com)
  • These MPNNs are then used in generative models based on a probabilistic diffusion process, which is found to produce interesting crystalline materials. (univ-artois.fr)
  • Utilizing a Hansen Solubility Parameter screening , we developed a swelling and in- diffusion process for tetraphenylporphyrin-complexed 64Cu, which permits one-pot labeling of polymer particles. (bvsalud.org)
  • [ 4 ] as well as revealing opposing patterns of diffusion changes in frontal and cerebellar regions of COVID-19 patients, suggesting the 2 regions react differently to viral infection. (medscape.com)
  • 275 (2017) illustrating the principles of multidimensional diffusion MRI. (lu.se)
  • We then introduce a feature editing strategy that modifies the input feature space of the diffusion model to further alleviate ``identity shortcuts'' and meanwhile improve the reconstruction quality of normal regions, leading to fewer false positive predictions. (arxiv.org)
  • In [ 13 , 14 ], a nonlocal model for diffusion that is analogous to the local porous medium equation is studied. (hindawi.com)
  • An increase in diffusion indicates effectiveness of the treatment in this animal model of prostate cancer metastasis. (diagnosticimaging.com)
  • For each manipulation, bias was quantified by fitting the drift diffusion model to the behavioral data. (jneurosci.org)
  • Schematic representation of the drift-diffusion model. (jneurosci.org)
  • A , Effects of bias explained by the drift-diffusion model. (jneurosci.org)
  • Title : A Model for Occupational Safety and Health Intervention Diffusion to Small Businesses Personal Author(s) : Sinclair, Raymond C.;Cunningham, Thomas R.;Schulte, Paul A. (cdc.gov)
  • To measure diffusion capacity , you breathe a harmless gas, called a tracer gas, for a very short time, often for only one breath. (medlineplus.gov)
  • Diffusion is driven by a gradient in Gibbs free energy or chemical potential. (wikipedia.org)
  • I have personally benefited immensely from this library, and I am confident that it will continue to empower researchers, engineers, and developers to explore and understand diffusion phenomena more efficiently and accurately. (vectorlinux.com)
  • The UM researchers used I-Response in their preclinical studies, which tracked bone water diffusion during the course of the animals' chemotherapy. (diagnosticimaging.com)
  • Using functional diffusion mapping, the researchers identified a statistically significant change in diffusion as early as seven days after the start of treatment. (diagnosticimaging.com)
  • There is already good reason to believe, however, that this technique, called functional diffusion mapping, will spur the scans to be done in the future. (diagnosticimaging.com)
  • Ross and Alnawaz Rehemtulla, Ph.D., a professor of radiation oncology and environmental health sciences at UM, have founded a company in Ann Arbor called ImBio, which has licensed the commercialization rights of the diffusion technique from the university. (diagnosticimaging.com)
  • So we partnered with Cedara Software to develop a turnkey package-a workstation solution-for functional diffusion mapping analysis of tumors. (diagnosticimaging.com)
  • Not only is the diffusion approach translatable from rodent to man because it is a similar MRI acquisition sequence, but the analysis of that data is also very translatable,' Ross said. (diagnosticimaging.com)
  • Results of search for 'su:{Diffusion of innovation. (who.int)
  • Diffusion-weighted MR of the bone may indicate within days whether and how well patients with metastatic cancer of the bone are responding to treatment. (diagnosticimaging.com)
  • The preclinical tests on mice show that diffusion mapping of bone may allow such an assessment to be made even sooner for patients with metastatic cancer of the bone. (diagnosticimaging.com)
  • If results are positive, functional diffusion mapping could have a major impact on the management of patients and healthcare costs. (diagnosticimaging.com)
  • The Division of Pulmonary Medicine at Cincinnati Children's performs diffusion tests. (cincinnatichildrens.org)
  • Diffusion tests measure gas transfer from the lungs into the bloodstream. (cincinnatichildrens.org)
  • Like all pulmonary testing, diffusion tests are patient effort dependent and are performed along with other tests. (cincinnatichildrens.org)
  • Tests using historical, cohort-linked aggregate data on cigarette diffusion, and individual-level data from the General Social Surveys covering the years from 1978 to 1994 and cohorts from 1889 to 1976 largely support the predictions. (who.int)
  • There are two ways to introduce the notion of diffusion: either a phenomenological approach starting with Fick's laws of diffusion and their mathematical consequences, or a physical and atomistic one, by considering the random walk of the diffusing particles. (wikipedia.org)
  • A distinguishing feature of diffusion is that it depends on particle random walk, and results in mixing or mass transport without requiring directed bulk motion. (wikipedia.org)
  • In comparing older to newer cohorts, the results show correspondence between the stage of cigarette diffusion and the direction and strength of the relationships of education, parental status, urban residence, and gender with cigarette smoking. (who.int)
  • For their new headquarters, they approached local distributor Enjoy Events to provide an accurate sound multi-diffusion solution with design integration and smart management from several remotes. (rcf.it)
  • One aspect that really impressed me about this library is its extensive collection of diffusion models. (vectorlinux.com)
  • It offers a wide range of models, including the popular Fickian and non-Fickian models, as well as more advanced models like fractional diffusion models. (vectorlinux.com)
  • These challenges were the motivation behind the organization of the Lorentz Center workshop on "Best Practices & Tools for Diffusion MR Spectroscopy" held in Leiden, the Netherlands, in September 2021. (lu.se)
  • Even if you are new to diffusion modeling, you can quickly get up to speed with this library and start exploring the fascinating world of diffusion processes. (vectorlinux.com)
  • Given the safety-critical nature of these components, traditional ultrasonic inspection is not sufficiently sensitive to the defects found in the diffusion bonds. (imperial.ac.uk)
  • At the end of the study, they removed the tumors and found the functional diffusion map had predicted the tumors' response to treatment. (diagnosticimaging.com)
  • In traditional diffusion MRI, short pulsed field gradients (PFG) are used for the diffusion encoding. (lu.se)
  • The central idea of diffusion, however, is common to all of these: a substance or collection undergoing diffusion spreads out from a point or location at which there is a higher concentration of that substance or collection. (wikipedia.org)
  • However, water diffuses asymmetrically in the white matter-that is, diffusion is restricted perpendicular to the long axis of the axons. (medscape.com)
  • Because living tumor cells slow the movement of water, the death of these cells is accompanied by an increase in water diffusion. (diagnosticimaging.com)
  • Constant concentration source in one dimension-the diffusion length. (wikipedia.org)
  • The photoacid diffusion length is a critical issue for EUV photoresists and photolithography because it governs critical dimension (CD), line-edge-roughness (LER) and line-width-roughness (LWR). (nist.gov)
  • Diffusion MRI is a powerful non-invasive method for studying molecular motion on the micrometer length scale and millisecond time scale. (lu.se)
  • There are no side effects from diffusion testing, and your child may resume normal activities after testing. (cincinnatichildrens.org)
  • Switzerland-based Huntsman Textile Effects reports it has engineered Univadine® DFM diffusion agent for increased migration and tone-on-tone build-up properties on polyester and polyester-blend fabrics. (textileworld.com)
  • Axial diffusion-weighted image (DWI) (top left), T2-weighted (T2W) image (top right), fluid-attenuated inversion recovery (FLAIR) image (bottom left), and contrast-enhanced T1W (bottom right) image demonstrate a right convexity meningioma, which appears hypointense on DWI image. (medscape.com)
  • The explanation predicts that, as cigarette diffusion proceeds and fashions change, the social determinants of smoking will shift across cohorts, such that initially positive relationships between pre-adult components of socioeconomic status and smoking in early cohorts become negative in later cohorts. (who.int)

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