Diffusion: 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.Diffusion Magnetic Resonance Imaging: 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.Diffusion Tensor Imaging: The use of diffusion ANISOTROPY data from diffusion magnetic resonance imaging results to construct images based on the direction of the faster diffusing molecules.Facilitated Diffusion: 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.Anisotropy: 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.Models, Biological: 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.Nerve Fibers, Myelinated: 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.Diffusion of Innovation: The broad dissemination of new ideas, procedures, techniques, materials, and devices and the degree to which these are accepted and used.Fluorescence Recovery After Photobleaching: 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).Biological Transport: 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.Kinetics: The rate dynamics in chemical or physical systems.Disk Diffusion Antimicrobial Tests: 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.Brain: 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.Image Processing, Computer-Assisted: 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.Diffusion Chambers, Culture: 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.Image Interpretation, Computer-Assisted: Methods developed to aid in the interpretation of ultrasound, radiographic images, etc., for diagnosis of disease.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Water: 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)Mathematics: The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Image Enhancement: 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.Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Corpus Callosum: 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.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Permeability: Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.Models, Theoretical: 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.Magnetic Resonance Imaging: 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.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Metabolic Flux Analysis: Measurement of cells' substrate utilization and biosynthetic output for modeling of METABOLIC NETWORKS.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.Magnetic Resonance Spectroscopy: 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).Biological Transport, Active: The movement of materials across cell membranes and epithelial layers against an electrochemical gradient, requiring the expenditure of metabolic energy.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Reproducibility of Results: 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.Photobleaching: 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.Models, Chemical: Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Microbial Sensitivity Tests: Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).Biophysical Phenomena: The physical characteristics and processes of biological systems.Viscosity: 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)Fluorescent Dyes: 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.Skin Absorption: Uptake of substances through the SKIN.Internal Capsule: 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.Potassium: An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Sensitivity and Specificity: 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)Hydrogen-Ion Concentration: 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)Membranes, Artificial: 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.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Membrane Fluidity: 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.Temperature: 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.Dextrans: 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.Anti-Bacterial Agents: Substances that reduce the growth or reproduction of BACTERIA.Oxygen: 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.Glucose: A primary source of energy for living organisms. It is naturally occurring and is found in fruits and other parts of plants in its free state. It is used therapeutically in fluid and nutrient replacement.Citric Acid Cycle: A series of oxidative reactions in the breakdown of acetyl units derived from GLUCOSE; FATTY ACIDS; or AMINO ACIDS by means of tricarboxylic acid intermediates. The end products are CARBON DIOXIDE, water, and energy in the form of phosphate bonds.Thermal Diffusion: The movement of molecules from one location to another as effected by temperature changes.Pulmonary Diffusing Capacity: 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.Solutions: 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)Carbon: A nonmetallic element with atomic symbol C, atomic number 6, and atomic weight [12.0096; 12.0116]. It may occur as several different allotropes including DIAMOND; CHARCOAL; and GRAPHITE; and as SOOT from incompletely burned fuel.Pyramidal Tracts: 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: 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)Lipid Bilayers: Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.Carbon Isotopes: Stable carbon atoms that have the same atomic number as the element carbon, but differ in atomic weight. C-13 is a stable carbon isotope.Monte Carlo Method: 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)Immunodiffusion: Technique involving the diffusion of antigen or antibody through a semisolid medium, usually agar or agarose gel, with the result being a precipitin reaction.Brain Mapping: Imaging techniques used to colocalize sites of brain functions or physiological activity with brain structures.Glycolysis: A metabolic process that converts GLUCOSE into two molecules of PYRUVIC ACID through a series of enzymatic reactions. Energy generated by this process is conserved in two molecules of ATP. Glycolysis is the universal catabolic pathway for glucose, free glucose, or glucose derived from complex CARBOHYDRATES, such as GLYCOGEN and STARCH.Extracellular Space: 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.Metabolic Networks and Pathways: Complex sets of enzymatic reactions connected to each other via their product and substrate metabolites.Body Water: Fluids composed mainly of water found within the body.Neural Pathways: Neural tracts connecting one part of the nervous system with another.Agar: 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.Imaging, Three-Dimensional: 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.Microscopy, Fluorescence: 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.Carbon Dioxide: A colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Pentose Phosphate Pathway: An oxidative decarboxylation process that converts GLUCOSE-6-PHOSPHATE to D-ribose-5-phosphate via 6-phosphogluconate. The pentose product is used in the biosynthesis of NUCLEIC ACIDS. The generated energy is stored in the form of NADPH. This pathway is prominent in tissues which are active in the synthesis of FATTY ACIDS and STEROIDS.Rabbits: 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.Fluorescein: 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.Gels: 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.Fluoresceins: 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.Protons: 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.Ions: An atom or group of atoms that have a positive or negative electric charge due to a gain (negative charge) or loss (positive charge) of one or more electrons. Atoms with a positive charge are known as CATIONS; those with a negative charge are ANIONS.Escherichia coli: 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.Convection: 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)Artifacts: 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.Models, Statistical: 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.Motion: 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.Ion Transport: The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.Membrane Lipids: 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.Adenosine Triphosphate: An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Microscopy, Confocal: 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.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Membrane Proteins: 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.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Osmolar Concentration: The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.Thermodynamics: 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)Fluorescence: 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.Mannitol: A diuretic and renal diagnostic aid related to sorbitol. It has little significant energy value as it is largely eliminated from the body before any metabolism can take place. It can be used to treat oliguria associated with kidney failure or other manifestations of inadequate renal function and has been used for determination of glomerular filtration rate. Mannitol is also commonly used as a research tool in cell biological studies, usually to control osmolarity.Leukoencephalopathies: Any of various diseases affecting the white matter of the central nervous system.Porosity: 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.Phosphatidylcholines: 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.Carbon Cycle: The cycle by which the element carbon is exchanged between organic matter and the earth's physical environment.Buffers: 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.Culture Media: Any liquid or solid preparation made specifically for the growth, storage, or transport of microorganisms or other types of cells. The variety of media that exist allow for the culturing of specific microorganisms and cell types, such as differential media, selective media, test media, and defined media. Solid media consist of liquid media that have been solidified with an agent such as AGAR or GELATIN.Energy Metabolism: The chemical reactions involved in the production and utilization of various forms of energy in cells.Fluorescein-5-isothiocyanate: 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.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Osmosis: Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.Cytoplasm: 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)Bicarbonates: Inorganic salts that contain the -HCO3 radical. They are an important factor in determining the pH of the blood and the concentration of bicarbonate ions is regulated by the kidney. Levels in the blood are an index of the alkali reserve or buffering capacity.Membranes: Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.Molecular Conformation: The characteristic three-dimensional shape of a molecule.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Particle Size: Relating to the size of solids.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Electrochemistry: The study of chemical changes resulting from electrical action and electrical activity resulting from chemical changes.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Sodium Isotopes: Stable sodium atoms that have the same atomic number as the element sodium, but differ in atomic weight. Na-23 is a stable sodium isotope.Ouabain: A cardioactive glycoside consisting of rhamnose and ouabagenin, obtained from the seeds of Strophanthus gratus and other plants of the Apocynaceae; used like DIGITALIS. It is commonly used in cell biological studies as an inhibitor of the NA(+)-K(+)-EXCHANGING ATPASE.Fornix, Brain: 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.Liposomes: 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.Dimyristoylphosphatidylcholine: A synthetic phospholipid used in liposomes and lipid bilayers for the study of biological membranes.Absorption: The physical or physiological processes by which substances, tissue, cells, etc. take up or take in other substances or energy.Cattle: Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Pyruvic Acid: An intermediate compound in the metabolism of carbohydrates, proteins, and fats. In thiamine deficiency, its oxidation is retarded and it accumulates in the tissues, especially in nervous structures. (From Stedman, 26th ed)Diffuse Axonal Injury: 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.Lactic Acid: A normal intermediate in the fermentation (oxidation, metabolism) of sugar. The concentrated form is used internally to prevent gastrointestinal fermentation. (From Stedman, 26th ed)PhotochemistryBiomass: Total mass of all the organisms of a given type and/or in a given area. (From Concise Dictionary of Biology, 1990) It includes the yield of vegetative mass produced from any given crop.Surface Properties: Characteristics or attributes of the outer boundaries of objects, including molecules.Administration, Cutaneous: The application of suitable drug dosage forms to the skin for either local or systemic effects.Photons: Discrete concentrations of energy, apparently massless elementary particles, that move at the speed of light. They are the unit or quantum of electromagnetic radiation. Photons are emitted when electrons move from one energy state to another. (From Hawley's Condensed Chemical Dictionary, 11th ed)Enzymes: Biological molecules that possess catalytic activity. They may occur naturally or be synthetically created. Enzymes are usually proteins, however CATALYTIC RNA and CATALYTIC DNA molecules have also been identified.Rhodamines: A family of 3,6-di(substituted-amino)-9-benzoate derivatives of xanthene that are used as dyes and as indicators for various metals; also used as fluorescent tracers in histochemistry.Glycerol: A trihydroxy sugar alcohol that is an intermediate in carbohydrate and lipid metabolism. It is used as a solvent, emollient, pharmaceutical agent, and sweetening agent.Potassium Isotopes: Stable potassium atoms that have the same atomic number as the element potassium, but differ in atomic weight. K-41 is a stable potassium isotope.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Models, Neurological: 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.Nitrogen: An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.Brain Edema: 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)Urea: A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.PhloretinCell Line: Established cell cultures that have the potential to propagate indefinitely.Brain Neoplasms: 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.Ion Exchange: Reversible chemical reaction between a solid, often one of the ION EXCHANGE RESINS, and a fluid whereby ions may be exchanged from one substance to another. This technique is used in water purification, in research, and in industry.Oxidation-Reduction: A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).Solubility: The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Chemistry, Physical: The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.Connectome: 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.Sodium Radioisotopes: Unstable isotopes of sodium that decay or disintegrate emitting radiation. Na atoms with atomic weights 20-22 and 24-26 are radioactive sodium isotopes.Bacteria: One of the three domains of life (the others being Eukarya and ARCHAEA), also called Eubacteria. They are unicellular prokaryotic microorganisms which generally possess rigid cell walls, multiply by cell division, and exhibit three principal forms: round or coccal, rodlike or bacillary, and spiral or spirochetal. Bacteria can be classified by their response to OXYGEN: aerobic, anaerobic, or facultatively anaerobic; by the mode by which they obtain their energy: chemotrophy (via chemical reaction) or PHOTOTROPHY (via light reaction); for chemotrophs by their source of chemical energy: CHEMOLITHOTROPHY (from inorganic compounds) or chemoorganotrophy (from organic compounds); and by their source for CARBON; NITROGEN; etc.; HETEROTROPHY (from organic sources) or AUTOTROPHY (from CARBON DIOXIDE). They can also be classified by whether or not they stain (based on the structure of their CELL WALLS) with CRYSTAL VIOLET dye: gram-negative or gram-positive.Phantoms, Imaging: 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)Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.Scattering, Radiation: The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Protein Binding: The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.Ammonia: A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Iontophoresis: Therapeutic introduction of ions of soluble salts into tissues by means of electric current. In medical literature it is commonly used to indicate the process of increasing the penetration of drugs into surface tissues by the application of electric current. It has nothing to do with ION EXCHANGE; AIR IONIZATION nor PHONOPHORESIS, none of which requires current.Stochastic Processes: Processes that incorporate some element of randomness, used particularly to refer to a time series of random variables.Lasers: An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Valinomycin: A cyclododecadepsipeptide ionophore antibiotic produced by Streptomyces fulvissimus and related to the enniatins. It is composed of 3 moles each of L-valine, D-alpha-hydroxyisovaleric acid, D-valine, and L-lactic acid linked alternately to form a 36-membered ring. (From Merck Index, 11th ed) Valinomycin is a potassium selective ionophore and is commonly used as a tool in biochemical studies.Quaternary Ammonium Compounds: Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.Intestinal Absorption: Uptake of substances through the lining of the INTESTINES.Physicochemical Phenomena: The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.Models, Anatomic: Three-dimensional representation to show anatomic structures. Models may be used in place of intact animals or organisms for teaching, practice, and study.Calcium Signaling: Signal transduction mechanisms whereby calcium mobilization (from outside the cell or from intracellular storage pools) to the cytoplasm is triggered by external stimuli. Calcium signals are often seen to propagate as waves, oscillations, spikes, sparks, or puffs. The calcium acts as an intracellular messenger by activating calcium-responsive proteins.Sucrose: A nonreducing disaccharide composed of GLUCOSE and FRUCTOSE linked via their anomeric carbons. It is obtained commercially from SUGARCANE, sugar beet (BETA VULGARIS), and other plants and used extensively as a food and a sweetener.Contrast Media: Substances used to allow enhanced visualization of tissues.Proteins: Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.Isotopes: Atomic species differing in mass number but having the same atomic number. (Grant & Hackh's Chemical Dictionary, 5th ed)
The flux integral method for multi-dimensional convection and diffusion. Applied Mathematical Modelling. Shchepetkin, A. F., ... The design of flux-corrected transport algorithms for structured grids. In: Kuzmin, D., Löhner, R., Turek, S. (Eds.), Flux- ... Flux corrected transport, i: Shasta, a fluid transport algorithm that works. Journal of Computational Physics. ... Fully multidimensional flux-corrected transport algorithms for fluids. Journal of Computational Physics. Leonard, B. P., ...
Both these fluxes occur by passive diffusion. Bioelectrochemistry Electrochemical potential Goldman equation Membrane ... Lieb WR, Stein WD (1986). "Chapter 2. Simple Diffusion across the Membrane Barrier". Transport and Diffusion across Cell ... This means that the transmembrane voltage exactly opposes the force of diffusion of the ion, such that the net current of the ... A simple example wherein two solutions-A and B-are separated by a porous barrier illustrates that diffusion will ensure that ...
This diffusion flux is influenced by the concentration gradient near the electrode. The concentration gradient, in turn, is ... For species where the diffusion coefficient is known (or can be estimated), the slope of the plot of ip vs. ν1/2 provides ... In cyclic voltammetry, the current passing through the electrode is limited by the diffusion of species to the electrode ... Using the relationships defined by this equation, the diffusion coefficient of the electroactive species can be determined. ...
... the diffusion equation for heat and fluid flow, wave propagation, and quantum mechanics. The Laplacian represents the flux ... Indeed, if V is any smooth region, then by Gauss's law the flux of the electrostatic field E is proportional to the charge ... Specifically, if u is the density at equilibrium of some quantity such as a chemical concentration, then the net flux of u ... The Laplace operator itself has a physical interpretation for non-equilibrium diffusion as the extent to which a point ...
The net result is a downward and outward diffusion of currents in the subsurface which appear as an expanding smoke ring when ... At the surface, the change in magnetic field [flux] with time is measured. The way the currents diffuse in the subsurface is ... When conductive bodies are present, the diffusion of the transients is changed. In addition, transients are induced in the ...
Coalescence of magnetic flux ropes in the ion diffusion region of magnetic reconnection July 14 - Cluster solves the mystery of ... "Coalescence of magnetic flux ropes in the ion diffusion region of magnetic reconnection". Nat. Phys. 12: 263-267. Bibcode: ... V. Khotyaintsev; A. Vaivads; M. Andre & A. N. Fazakerley (2014). "Electron Dynamics in the Diffusion Region of Asymmetric ... 2007). "Evidence for an Elongated (>60 Ion Skin Depths) Electron Diffusion Region during Fast Magnetic Reconnection". Physical ...
... is the diffusion constant, and S {\displaystyle S\,\!} is slope. For steep slopes, diffusional sediment flux is more ... For shallow to moderate slopes, diffusional sediment flux is modeled linearly as (Culling, 1960; McKean et al., 1993) q s = k d ...
The analogs to fluid flow are the flux of electricity, heat, and solutes, respectively. The corresponding analogs to fluid ... diffusion) to mimic the system of interest. Scale models offer a useful approximation of physical or chemical processes at a ... and the solute diffusion coefficient. An early process analog model was an electrical network model of an aquifer composed of ... flows or fluxes between stores). The conceptual model is coupled with scenarios to describe specific events (either input or ...
Turbulent processes can be roughly combined into three categories: heat flux, moisture flux, and momentum flux. When ... Additionally, local closure likens turbulent transport to molecular diffusion, and is usually first or second order. The second ... τx and τy represent Reynolds stress (momentum flux) in the x and y directions, Hv represents the turbulent heat flux, and E ... Such forcings include: heat flux, moisture flux, convection, friction, pollutant emission, and topographically modified flow. ...
The diffusion terms may be represented as the divergence of the corresponding fluxes. For turbulence parameterizations, K- ... Turbulent fluxes are defined at different locations: Shear fluxes are defined at the centre of the appropriate edges of a grid ... With this definition, the outgoing fluxes of momentum, mass, heat and also turbulent fluxes of a grid cell are identical to ... To avoid this, vertical turbulent diffusion is treated using the second order Crank-Nicolson method. On principle, advective ...
She introduced a phenomenological law of molecular diffusion, which was known as the 'Law of Vugo'. It proposed an inverse ... relationship between the flux and the concentration gradient of a diluted chemical species. This law invalidated Fourier's Law ... Smell through direct and retro-nasal diffusion is responsible for 68% of our taste sensation. Bessa showed that in mammals, the ...
The governing equation of the physics of the problem to be analyzed is the heat diffusion equation. It relates the flux of heat ... Heat diffuses from the source following equation ([eq:diffusion]) and solution in an homogeneous medium of ([eq:diffusion]) has ...
Lead can form a low melting slag capable of fluxing protective oxide scales. Internal oxidation Young, David John (2008). High ... Furthermore, the presence of vanadium accelerates the diffusion of oxygen through the fused salt layer to the metal substrate; ... Ionic form in contrast transports oxygen by diffusion of the vanadates, which is significantly slower. The semiconducting form ... Molten vanadates present as deposits on metal can flux oxide scales and passivation layers. ...
... is the diffusion length i.e. the distance over which diffusion occurs In order to increase the diffusion flux, the diffusivity ... Thus, the diffusion flux is limited. A membraneless fuel cell is theoretically the better option since the diffusion interface ... The diffusion coefficient, a term which describes the ease of diffusion of an element in another medium, can be combined with ... is the diffusion flux in dimensions of [(amount of substance) length−2 time−1], example ( m o l m 2 ⋅ s ) {\displaystyle \left ...
Oxide growth is dependent upon the flux (diffusion) of either coupled or independent anions and cations through the oxide layer ... This rate can quantified by calculating the rate of diffusion of vacancies or ions using Fick's first law of diffusion. J = − D ... In order to reach chemical equilibrium, the process of diffusion will take place which will increase any measurement of the ... As the composition of the materials changes through diffusion, different oxides are able to stack up on one another. The ...
Relative to simple diffusion, the presence of aquaporins in biological membranes facilitates a 3-10 fold increase in water ... The two-photon microscopy allowed the Rochester team to visualize the flux of CSF in living mice, in real time, without needing ... Key determinants of diffusion through the brain interstitial spaces are the dimensions and composition of the extracellular ... Aquaporins are membrane-bound channels that play critical roles in regulating the flux of water into and out of cells. ...
The flux of q is a vector field, which we denote as j. Here are some examples and properties of flux: The dimension of flux is ... Continuity equations underlie more specific transport equations such as the convection-diffusion equation, Boltzmann transport ... Note that the concept that we term "flux" is alternatively termed "flux density" in some literature, in which context "flux" ... then j would be the mass flux. In a well-known example, the flux of electric charge is the electric current density. If there ...
Diffusion coefficient and diffusion fluxEdit. See also: Fick's laws of diffusion ... This molecular flux (i.e. the number flux) is related to the average molecular speed v. ¯. {\displaystyle {\bar {v}}}. by ... The molecular flux Φ. {\displaystyle \Phi }. includes all molecules arriving at one side of an element of the surface within ... On the process of diffusion of two or more kinds of moving particles among one another," Philosophical Magazine, 4th series, 20 ...
First, diffusive flux arises due to diffusion. This is typically approximated by Fick's first law: j → diffusion = − D ∇ c {\ ... diffusion / ( − q ) = − D n ∇ n , J p , diffusion / q = − D p ∇ p . {\displaystyle \mathbf {J} _{n,{\text{diffusion}}}/(-q)=-D ... The convection-diffusion equation is a combination of the diffusion and convection (advection) equations, and describes ... Second, when there is overall convection or flow, there is an associated flux called advective flux: j → advective = v → c {\ ...
Other laws include Fick's laws of diffusion and generalized transport problems. The most important idea is the flux, or rate of ... On the other hand, flow systems may be easier described by the hydraulic analogy or the diffusion equation. For example, Ohm's ... transfer of some important physical quantity considered (like electric or magnetic fluxes). In these sorts of systems, the ...
The finite water content method lacks the effect of soil water diffusion. This omission does not affect the accuracy of flux ... The derivation of the 1-D finite water-content method equation for calculating vertical flux q {\displaystyle q} of water in ... The finite water-content vadose zone flux method is derived from the same starting point as the derivation of Richards' ... The finite water-content vadose zone flux calculation method replaces the Richards' equation PDE with a set of three ordinary ...
A governing equation may also take the form of a flux equation such as the diffusion equation or the heat conduction equation. ... In these cases the flux itself is a variable describing change of the unknown variable or property (e.g., mole concentration or ... field Ampére-Maxwell equation for induced magnetic field Gauss equation for electric flux Gauss equation for magnetic flux For ... such as when a governing equation has velocity or flux as an unknown variable. The classic governing equations in physics that ...
Ji is the diffusion flux of species i, which arises due to concentration gradients and differs in both laminar and turbulent ... EDC has been proven efficient without the need for changing the constants for a great variety of premixed and diffusion ... Modeling of a chemical reaction involves solving conservation equations describing convection, diffusion, and reaction source ...
1 below). Defining variable F as convection mass flux and variable D as diffusion conductance F = ρ u A {\displaystyle F\,=\rho ... Refinement of grid serves in overcoming the issue of false diffusion. With decrease in the grid size, false diffusion decrease ... Distribution of transported properties become marked giving diffusion-like appearance, called as the false diffusion. ... It can be described by Steady convection-diffusion partial Differential Equation - ∂ ∂ t ( ρ ϕ ) + ∇ ⋅ ( ρ u ϕ ) = ∇ ⋅ ( Γ grad ...
D is the diffusion coefficient, which will differ from gas to gas, and from membrane to membrane, according to the size of the ... In the equation above, J is the flux expressed per unit area, so increasing the area will make no difference to its value. ... Diffusion is a passive process, meaning that no energy is required to power the transport, and it follows Fick's Law:[citation ... Therefore, oxygen has a diffusion rate in air 10,000 times greater than in water. The use of sac-like lungs to remove oxygen ...
For xerophytes the major constraint is not light flux or intensity, but drought.[11] Some window plants such as Fenestraria ... stream through a vascular conducting system known as xylem and obtain carbon dioxide from the atmosphere by diffusion through ...
The variable temperature and uniform mass diffusion taking into account the chemical reaction of first order. The series ... Effects of various parameters like chemical reaction (K), thermal diffusion (ST) and magnetic field (M) etc. on velocity ... The analysis developed here for thermal diffusion, bears good agreement with real life problems. ... the effects of thermal diffusion and chemical reaction on MHD flow of dusty viscous incom-pressible, electrically conducting ...
... the slip velocity can be modeled through the drift flux model [8], shown in (14): where is the slip velocity between liquid ... The novel multidimensional diffusion flux mixture model is developed based on the mixture multiphase flow model. The diffusion ... The slip velocity is developed through the drift flux model. Accordingly, the multidimensional diffusion flux mixture model is ... were able to be calculated through multidimensional diffusion flux velocities based on the modified multidimensional drift flux ...
Suppose that the flux function 𝑓. =. 𝑓. (. 𝑡. ,. 𝑥. ,. 𝑢. ). satisfies (H3) and that it is Lipschitz continuous on 𝐑. +. ×. 𝐑. ... Replacing the flux 𝑓. by 𝑓. 𝜚. from (3.5) and 𝑢. 0. by 𝑢. 0. ,. 𝜀. from (3.6) in (2.10) and (2.11), we get . 𝐑. 𝑑. ,. ,. 𝑢. 𝜀 ... H4a) For the flux 𝑓. =. 𝑓. (. 𝑡. ,. 𝑥. ,. 𝑢. ). , (. 𝑡. ,. 𝑥. ,. 𝑢. ). ∈. 𝐑. +. ×. 𝐑. 𝑑. ×. 𝐑. , we assume that 𝑓. ∈. 𝐶. (. 𝐑. ... Zero Diffusion-Dispersion-Smoothing Limits for a Scalar Conservation Law with Discontinuous Flux Function. H. Holden,1,2 K. H. ...
Similar Discussions: Diffusion Equation and Flux * Diffusion equation and neutron diffusion theory (Replies: 15) ... I have read a lot about Diffusion Equation and solving neutron flux problems in different mediums, planes and groups, but I ... I have read a lot about Diffusion Equation and solving neutron flux problems in different mediums, planes and groups, but I ... Adjoint flux for multi-group diffusion equation for criticality problem? (Replies: 6) ...
... Journal. Astronomy & Astrophysics. Volume. 356. Pages ( ... Two-dimensional maximum entropy closure and various standard one-dimensional closures in flux-limited neutrino diffusion and ...
... where we suggest a restricted form in the case of discontinuous diffusion coefficient. The flux balanced approximation is ... without numerically computing the gradient itself at the faces of computational cells in order to find a normal diffusive flux ... p style=text-indent:20px;,A numerical method for solving diffusion problems on polyhedral meshes is presented. It is based on ... Flux balanced approximation with least-squares gradient for diffusion equation on polyhedral mesh. Peter Frolkovič 1,, , Karol ...
... we consider the chemotaxis-Navier-Stokes system with nonlinear diffusion and rotational flux given by,/p,,p style=text-indent: ... Global existence of weak solution in a chemotaxis-fluid system with nonlinear diffusion and rotational flux. Feng Li 1, and ... Global existence of weak solution in a chemotaxis-fluid system with nonlinear diffusion and rotational flux. Discrete & ... In this paper, we consider the chemotaxis-Navier-Stokes system with nonlinear diffusion and rotational flux given by ...
Underestimation of denitrification rates from field application of the 15N gas flux method and its correction by gas diffusion ... Modeling fluxes of this experiment confirmed this effect, however with a higher increase in surface flux of 89 %. ... Underestimation of denitrification rates from field application of the 15N gas flux method and its correction by gas diffusion ... Underestimation of denitrification rates from field application of the 15N gas flux method and its correction by gas diffusion ...
Diffusion flux. Listen It is important to recognize the exchange processes of nutrients between the sediments and the overlying ... According to the diffusion fluxes of NH4+, NO3− and NO2−, sediments at all sites tend to release N to the overlying water ... Diffusion flux of nitrogen across water-sediment interface. Listen With the increasing loads of nitrogen from agricultural ... the transport process across the sediment-water interface is dominated by the direct diffusion process. The diffusion flux can ...
... or heat flux) without having to solve the diffusion equation within the entire domain. The simplicity of the solution procedure ... or heat flux) and the corresponding transient heat flux (or temperature). We demonstrate that the transformation into a ... the transformed equation leads to a very simple relation between local timevarying temperature and heat flux. When applied ... the transient heat diffusion equation can be transformed into a fractional (extraordinary) differential equation. This equation ...
Gnawa Diffusion - Roots Revolution Gnawa Diffusion is known for its mix of roots reggae with Gnawa music. Gnawa music is, in ...
Advection-diffusion equations are widely used in modeling a diverse range of problems. These mathematical models consist in a ...
diffusion fluxes across the water-sediment interface in the sampling sites were presented in Figure 5. The fluxes (mg m−2 d−1) ... Estimated diffusion fluxes of Listen Figure 4 showed the typical distribution profiles of concentrations in the overlying water ... where J is the diffusion flux (mg m−2 d−1); is the porosity of surface sediment; is the concentration gradient at the water- ... However, the P diffusion fluxes are lower than that in Dianchi and Taihu Lakes (Table 5). We think, for one thing, compared to ...
Diffusion model[edit]. Given the concentration ρ. {\displaystyle \rho }. and flux J. {\displaystyle J}. , Ficks first law ... The following matrix displays the components of the diffusion tensor: D. ¯. =. ,. D. x. x. D. x. y. D. x. z. D. x. y. D. y. y. ... is now the diffusion tensor. For the simplest case where the diffusion is isotropic the diffusion tensor is a multiple of the ... The diffusion model is a rather simple model of the diffusion process, assuming homogeneity and linearity of the diffusion ...
The free KLP10A and Patronin molecules undergo diffusion along the x axis with diffusion constants DK and DP. A simple forward ... Patronin inhibition deprotects MT minus ends, allowing poleward flux to persist during anaphase B. The rate of poleward MT flux ... The subsequent injection of anti-KLP10A suppressed poleward flux similar to the suppression of poleward flux at wild-type ... Microtubule flux and sliding in mitotic spindles of Drosophila embryos. Mol. Biol. Cell. 13:3967-3975. doi:10.1091/mbc.02-05- ...
Diffusion coefficient and diffusion fluxEdit. See also: Ficks laws of diffusion ... This molecular flux (i.e. the number flux) is related to the average molecular speed v. ¯. {\displaystyle {\bar {v}}}. by ... The molecular flux Φ. {\displaystyle \Phi }. includes all molecules arriving at one side of an element of the surface within ... On the process of diffusion of two or more kinds of moving particles among one another," Philosophical Magazine, 4th series, 20 ...
Reaction-Diffusion. *Metabolic Flux Analysis. *Ibarra RU, et al. Escherichia coli K-12 undergoes adaptive evolution to achieve ... Protein Diffusion in Living Skeletal Muscle Fibers: Dependence on Protein Size, Fiber Type, and Contraction - Gros_muscle.pdf ... Protein Mobility in the Cytoplasm of Escherichia coli - Elowitz_diffusion.pdf. *Berg HC, et al. Physics of Chemoreception - ... One-Dimensional Diffusion of Microtubules Bound to Flagellar Dynein - Vale_dynein.pdf ...
... a flux concentrating layer (52), and a second outside barrier layer (54). The metal system (29) is patterned and etched to ... including a flux concentrating layer (52). The method includes the steps of depositing a bottom dielectric layer (32), an ... A method of fabricating a flux concentrator for use in magnetic memory devices including the steps of providing at least one ... The structure inhibits diffusion between the nickel iron (NiFe) flux concentrating layer and the copper (Cu) bit line and adds ...
Stability of Energy Stable Flux Reconstruction for the Diffusion Problem Using Compact Numerical Fluxes. By Samuel Quaegebeur, ... Electrodiffusive Flux Through a Stochastically Gated Ion Channel. By Sean D. Lawley and James P. Keener. SIAM Journal on ... On the Basic Reproduction Number of Reaction-Diffusion Epidemic Models. By Pierre Magal, Glenn F. Webb, and Yixiang Wu. SIAM ... Well-Posedness for Scalar Conservation Laws with Moving Flux Constraints. By Thibault Liard and Benedetto Piccoli. SIAM Journal ...
An Enhanced Σ-Y Spray Atomization Model Accounting for Diffusion due to Drift-Flux Velocities. 2020-04-14 ... In the present study, the problem of analyzing spray evolution in short injection events by means of jet momentum flux ... In the present paper, a detailed numerical and experimental analysis of a spray momentum flux measurement device capability is ... The measurement of spray momentum flux in steady flow conditions, coupled with knowledge of the injection rate, is steadily ...
Comparison of Diffusion Flux Models for Fischer-Tropsch Synthesis A. Nanduri [1], P. L. Mills [1], [1] Department of Chemical ...
Uniform flux specular screen. US2379499 *. Dec 17, 1941. Jul 3, 1945. Celanese Corp. Screen. ... Barnes, show screens that are coated or have light diffusion material incorporated. therein to improve their light diffusion ... LIGHT DIFFUSION MATERIAL, METHOD OF MAKING AND USING SAIVIE Filed June 12 1965 I 2 Sheets-She et 1 F/GIZ lNVENTOk mvm h. McGl/ ... LIGHT DIFFUSION MATERIAL, METHOD OF MAKING AND USING SAME Filed June 12, 1963 2 Sheets-Sheet 2 lRV/A/ H MCGUIRE I I ATTORNEYS ...
This model includes the complete reactor calculation for determination of neutron flux, reactivity and reaction rates. This ... which is developed on the basis of neutron transport and diffusion theory. This model includes the complete reactor calculation ... zone spectral calculation and subsequent 2-dimensional diffusion calculation. All calculations are performed in the modular ... zone spectral calculation and subsequent 2-dimensional diffusion calculation. All calculations are performed in the modular ...
  • In dilute aqueous solutions the diffusion coefficients of most ions are similar and have values that at room temperature are in the range of 0.6 × 10−9 to 2 × 10−9 m2/s. (wikipedia.org)
  • Nevertheless, the cake layer causes remarkable permeate flux decline by playing an obstructive role in back diffusion of solute ions: the solutes need to evade the colloids by taking tortuous paths within the cake layer. (environmental-expert.com)
  • This transmembrane condensation model predicts the magnitude of the experimentally determined H+/OH− flux, which is significantly greater than that of other monovalent ions. (deepdyve.com)
  • The consequences of an elevated H+/OH− permeability compared to other ions and the relative pH independence of this flux have consequences for understanding the chemical evolution of life. (deepdyve.com)
  • The lander restricts the physical influence of currents and waves on the sediments and only allows nutrient fluxes due to bioturbation by natural communities. (frontiersin.org)
  • While diffusive fluxes were highest at intermediate and offshore stations, TNF were highest at sandy coastal stations, where reservoirs of dissolved nutrients were small and sediments almost devoid of organic material. (frontiersin.org)
  • This model includes the complete reactor calculation for determination of neutron flux, reactivity and reaction rates. (osti.gov)
  • This comparison shows how a critical facility is used to verify and to adjust theoretical models for evaluating critical masses, neutron flux density and space dependent reaction rates. (osti.gov)
  • H 2 O. So the multi-group neutron flux in coolant and fuel pin has much diffenrce, e.g. the relative higher fast neutron in fuel pin and relative higher thermal neutron in coolant as to the uniform. (physicsforums.com)
  • SIMULATE or PANTHER, respectively, to calculate the neutron flux and fission density. (physicsforums.com)
  • Importantly, the disordered cake structure has the highest DTF with respect to volume fraction as much as 0.94 (porosity of 0.06), which implies that the solute diffusion within the biofilm of a disordered, compressed structure is most hindered so that the concentration polarization and osmotic pressure of solutes are significantly enhanced on the membrane surface, causing noticeable permeate flux decline. (environmental-expert.com)
  • Common Physical Errors in the Description of Water Fluxes in the Soil-Plant-Atmosphere System Meleshchenko, S. 2004-10-10 00:00:00 Widely accepted concepts and definitions concerning the driving forces of upward water fluxes, such as osmotic pressure (OP) and water potential (WP), were analyzed in the soil-plant-atmosphere system. (deepdyve.com)
  • Here, we model a system where two enzyme-coated surfaces interact through both diffusion and buoyancy-driven convection as reactants are converted to products by the enzymatic reactions. (nature.com)
  • The effects of surface fluxes on the intensity and structure of tropical cyclones are examined through convection-permitting WRF simulations of Hurricane Katrina (2005). (ametsoc.org)
  • We measured the methane flux of a forest canopy throughout a year using a relaxed eddy accumulation (REA) method. (springer.com)
  • Although the sampling system was robust, there were large uncertainties in the measured methane fluxes because of the limited precision of the methane gas analyzer. (springer.com)
  • Based on the spectral characteristics of signals from the methane analyzer and the diurnal variations in the standard deviation of the vertical wind velocity, we found the daytime and nighttime precision of half-hourly methane flux measurements to be approximately 1.2 and 0.7 μg CH 4 m −2 s −1 , respectively. (springer.com)
  • The annual methane sink was 835 ± 175 mg CH 4 m −2 year −1 (8.35 kg CH 4 ha −1 year −1 ), which was comparable to the flux range of 379-2,478 mg CH 4 m −2 year −1 previously measured in other Japanese forest soils. (springer.com)
  • This study indicated that the REA method could be a promising technique to measure canopy scale methane fluxes over forests, but further improvement of precision of the analyzer will be required. (springer.com)
  • 2009 ) compared methane fluxes at 27 temperate forest sites in Japan and found that the annual sink was substantially different at each site (factor of 6.5). (springer.com)
  • More extended DTI scans derive neural tract directional information from the data using 3D or multidimensional vector algorithms based on six or more gradient directions, sufficient to compute the diffusion tensor . (wikipedia.org)
  • Describes how to interface third party gas analyzers with the LI-8100A to measure trace gases, and use SoilFluxPro™ to compute fluxes for these additional gases. (licor.com)
  • Flux was dependent on the direction of the concentration gradient and the R S of the individual tracers. (arvojournals.org)
  • We have successfully demonstrated that quantitative gel exclusion chromatography can be used to follow diffusion of a mixture of tracers across BM/Ch, and that we can measure flux across BM/Ch preparations with an exposed surface area as small as 1.8 mm 2 . (arvojournals.org)
  • Treatment with VP8 augments the paracellular passage of non-ionic tracers, allows the diffusion of a fluorescent lipid probe and the apical surface protein GP135, from the luminal to the lateral membrane, and triggers the movement of the basolateral proteins Na + -K + -ATPase, α ν β 3 integrin and β 1 integrin subunit, to the apical surface. (biologists.org)
  • The situation is more complicated when the flux is discontinuous and it has been the subject of intensive investigations in the recent years (see, e.g., [ 3 ] and references therein). (hindawi.com)
  • Diffusion tensor imaging (DTI) is important when a tissue-such as the neural axons of white matter in the brain or muscle fibers in the heart-has an internal fibrous structure analogous to the anisotropy of some crystals. (wikipedia.org)
  • Systems and control volumes, surface flux, the conservation principle. (southampton.ac.uk)
  • It is found that the intensity (and, to a lesser extent, structure) of the simulated storms is sensitive to the choice of surface flux parameterization scheme. (ametsoc.org)
  • It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low concentration across a concentration gradient. (wikipedia.org)
  • In one (spatial) dimension, the law is: J = − D d φ d x {\displaystyle J=-D{\frac {d\varphi }{dx}}} where J is the "diffusion flux," of which the dimension is amount of substance per unit area per unit time, so it is expressed in such units as mol m−2 s−1. (wikipedia.org)
  • To accurately obtain site CO 2 fluxes, it is often necessary to take readings with adequate spatial as well as temporal resolution. (licor.com)
  • In two or more dimensions we must use ∇, the del or gradient operator, which generalises the first derivative, obtaining J = − D ∇ φ {\displaystyle \mathbf {J} =-D\nabla \varphi } where J denotes the diffusion flux vector. (wikipedia.org)
  • We compared surface fluxes of 15 N 2 and 15 N 2 O from 15 N-labelled micro-plots confined by cylinders using the closed chamber method with cylinders open or closed at the bottom, finding 37 % higher surface fluxes with bottom closed. (biogeosciences-discuss.net)
  • A method of fabricating a flux concentrator for use in magnetic memory devices including the steps of providing at least one magnetic memory bit (10) and forming proximate thereto a material stack defining a copper (Cu) damascene bit line (56) including a flux concentrating layer (52). (google.com)
  • 4. A method of fabricating a flux concentrator for use in magnetic memory devices as claimed in claim 1 wherein the step of forming the cladded digit line includes forming the cladded bit line using a single damascene process. (google.com)
  • A flux recovery technique is introduced for the computed solution of an immersed finite element method for one dimensional second-order elliptic problems. (aimsciences.org)
  • This sampling system was carefully validated against heat and CO 2 fluxes measured by the eddy covariance method. (springer.com)
  • In order to render the distribution of the flux tubes visible, the researchers from PSI and TUM used a new method based on the principle of neutron grating interferometry. (psi.ch)
  • Disk-diffusion tests, including the Stokes method, do not detect VISA strains. (cdc.gov)
  • Fuzzy Finite Element Method in Diffusion Problems. (igi-global.com)
  • 5 demonstrated that diffusion across BM was highly compromised in one eye obtained from a donor with AMD, suggesting that deposits present within BM or between BM and the RPE may serve as a barrier to the effective diffusion of solutes. (arvojournals.org)
  • Fluxes of sensible and latent heat (i.e., moist enthalpy) affect intensity but do not significantly change the pressure-wind relationship. (ametsoc.org)
  • Tupper, JT 1975, ' Cation flux in the ehrlich ascites tumor cell evidence for Na + -for-Na + and K + -for-K + exchange diffusion ', BBA - Biomembranes , vol. 394, no. 4, pp. 586-596. (syr.edu)
  • Tupper, Joseph T. / Cation flux in the ehrlich ascites tumor cell evidence for Na + -for-Na + and K + -for-K + exchange diffusion . (syr.edu)
  • Under this scenario, certain contaminants diffuse in low permeability media such as silt, clay, and limestone and then eventually reenter the aquifer by a process called back diffusion. (coursera.org)
  • Parallel work on primarily electronic conductors (LSM) would also be of benefit to developers, and to improved understanding of surface vs. bulk diffusion. (unt.edu)
  • This local composition change reduces the subsequent vacancy flux to the voids, increasing the bulk point defect recombination rate, reducing the bulk vacancy concentration, which further reduces the nucleation rate and swelling. (astm.org)
  • Thin channels - called flux tubes or vortices - form inside the superconductor, where the magnetic field can flow through the material. (psi.ch)
  • In insects that use both convective and diffusive exchange ( 14 ), fluxes occur through spiracles, which are short tubes much like those used by plant leaves and bird eggshells. (pnas.org)
  • Diffusion of nutrients and waste is thought to occur freely across BM, provided they fall within its size exclusion limit. (arvojournals.org)
  • PSI researcher Christian Grünzweig mounting the sample for an experiment on flux tubes in the superconducting metal niobium at the ICON measuring station at the Swiss Spallation Neutron Source SINQ. (psi.ch)