Electric Impedance: The resistance to the flow of either alternating or direct electrical current.Plethysmography, Impedance: Recording changes in electrical impedance between electrodes placed on opposite sides of a part of the body, as a measure of volume changes in the path of the current. (Stedman, 25th ed)Cardiography, Impedance: A type of impedance plethysmography in which bioelectrical impedance is measured between electrodes positioned around the neck and around the lower thorax. It is used principally to calculate stroke volume and cardiac volume, but it is also related to myocardial contractility, thoracic fluid content, and circulation to the extremities.Electric Organ: In about 250 species of electric fishes, modified muscle fibers forming disklike multinucleate plates arranged in stacks like batteries in series and embedded in a gelatinous matrix. A large torpedo ray may have half a million plates. Muscles in different parts of the body may be modified, i.e., the trunk and tail in the electric eel, the hyobranchial apparatus in the electric ray, and extrinsic eye muscles in the stargazers. Powerful electric organs emit pulses in brief bursts several times a second. They serve to stun prey and ward off predators. A large torpedo ray can produce of shock of more than 200 volts, capable of stunning a human. (Storer et al., General Zoology, 6th ed, p672)Dielectric Spectroscopy: A technique of measuring the dielectric properties of materials, which vary over a range of frequencies depending on the physical properties of the material. The technique involves measuring, over a range of frequencies, ELECTRICAL IMPEDANCE and phase shift of an electric field as it passes through the material.Electromagnetic Fields: Fields representing the joint interplay of electric and magnetic forces.Gymnotiformes: An order of neotropical electric fish found chiefly in the waters of South America. They continually emit weak electric discharges, which they use in object location and communication. A most popular species of research interest is the electric eel, ELECTROPHORUS electricus.Tomography: Imaging methods that result in sharp images of objects located on a chosen plane and blurred images located above or below the plane.Encyclopedias as Topic: Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.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)Body Composition: The relative amounts of various components in the body, such as percentage of body fat.Body Water: Fluids composed mainly of water found within the body.Anthropometry: The technique that deals with the measurement of the size, weight, and proportions of the human or other primate body.Transcutaneous Electric Nerve Stimulation: The use of specifically placed small electrodes to deliver electrical impulses across the SKIN to relieve PAIN. It is used less frequently to produce ANESTHESIA.Electrodes, Implanted: Surgically placed electric conductors through which ELECTRIC STIMULATION is delivered to or electrical activity is recorded from a specific point inside the body.Electric Stimulation Therapy: Application of electric current in treatment without the generation of perceptible heat. It includes electric stimulation of nerves or muscles, passage of current into the body, or use of interrupted current of low intensity to raise the threshold of the skin to pain.Deep Brain Stimulation: Therapy for MOVEMENT DISORDERS, especially PARKINSON DISEASE, that applies electricity via stereotactic implantation of ELECTRODES in specific areas of the BRAIN such as the THALAMUS. The electrodes are attached to a neurostimulator placed subcutaneously.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Subthalamic Nucleus: Lens-shaped structure on the inner aspect of the INTERNAL CAPSULE. The SUBTHALAMIC NUCLEUS and pathways traversing this region are concerned with the integration of somatic motor function.Algorithms: A procedure consisting of a sequence of algebraic formulas and/or logical steps to calculate or determine a given task.Bronchoscopy: Endoscopic examination, therapy or surgery of the bronchi.Scalp: The outer covering of the calvaria. It is composed of several layers: SKIN; subcutaneous connective tissue; the occipitofrontal muscle which includes the tendinous galea aponeurotica; loose connective tissue; and the pericranium (the PERIOSTEUM of the SKULL).Bayes Theorem: A theorem in probability theory named for Thomas Bayes (1702-1761). In epidemiology, it is used to obtain the probability of disease in a group of people with some characteristic on the basis of the overall rate of that disease and of the likelihood of that characteristic in healthy and diseased individuals. The most familiar application is in clinical decision analysis where it is used for estimating the probability of a particular diagnosis given the appearance of some symptoms or test result.Markov Chains: A stochastic process such that the conditional probability distribution for a state at any future instant, given the present state, is unaffected by any additional knowledge of the past history of the system.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)Countercurrent Distribution: A method of separation of two or more substances by repeated distribution between two immiscible liquid phases that move past each other in opposite directions. It is a form of liquid-liquid chromatography. (Stedman, 25th ed)Periodicals as Topic: A publication issued at stated, more or less regular, intervals.Polyethylene Glycols: Polymers of ETHYLENE OXIDE and water, and their ethers. They vary in consistency from liquid to solid depending on the molecular weight indicated by a number following the name. They are used as SURFACTANTS, dispersing agents, solvents, ointment and suppository bases, vehicles, and tablet excipients. Some specific groups are NONOXYNOLS, OCTOXYNOLS, and POLOXAMERS.Advertising as Topic: The act or practice of calling public attention to a product, service, need, etc., especially by paid announcements in newspapers, magazines, on radio, or on television. (Random House Unabridged Dictionary, 2d ed)Time Factors: Elements of limited time intervals, contributing to particular results or situations.Mass Media: Instruments or technological means of communication that reach large numbers of people with a common message: press, radio, television, etc.Questionnaires: Predetermined sets of questions used to collect data - clinical data, social status, occupational group, etc. The term is often applied to a self-completed survey instrument.Dermatitis, Irritant: A non-allergic contact dermatitis caused by prolonged exposure to irritants and not explained by delayed hypersensitivity mechanisms.Irritants: Drugs that act locally on cutaneous or mucosal surfaces to produce inflammation; those that cause redness due to hyperemia are rubefacients; those that raise blisters are vesicants and those that penetrate sebaceous glands and cause abscesses are pustulants; tear gases and mustard gases are also irritants.Dermatitis, Occupational: A recurrent contact dermatitis caused by substances found in the work place.Dermatitis, Allergic Contact: A contact dermatitis due to allergic sensitization to various substances. These substances subsequently produce inflammatory reactions in the skin of those who have acquired hypersensitivity to them as a result of prior exposure.Cardiac Output: The volume of BLOOD passing through the HEART per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with STROKE VOLUME (volume per beat).Meridians: Classical loci in ACUPUNCTURE. They are main and collateral channels, regarded as a network of passages, through which vital energy (Qi) circulates and along which acupoints (ACUPUNCTURE POINTS) are distributed. The meridians are a series of 14 lines upon which more than 400 acupoints are located on the body. (The Pinyin Chinese-English Dictionary, p. 359; Dr. Wu Lancheng, Academy of Traditional Chinese Medicine, Beijing)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)Zirconium: Zirconium. A rather rare metallic element, atomic number 40, atomic weight 91.22, symbol Zr. (From Dorland, 28th ed)Ceramics: Products made by baking or firing nonmetallic minerals (clay and similar materials). In making dental restorations or parts of restorations the material is fused porcelain. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed & Boucher's Clinical Dental Terminology, 4th ed)Blood Viscosity: The internal resistance of the BLOOD to shear forces. The in vitro measure of whole blood viscosity is of limited clinical utility because it bears little relationship to the actual viscosity within the circulation, but an increase in the viscosity of circulating blood can contribute to morbidity in patients suffering from disorders such as SICKLE CELL ANEMIA and POLYCYTHEMIA.Magnetometry: The measurement of various aspects of MAGNETIC FIELDS.Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.Uterine Monitoring: Measurement or recording of contraction activity of the uterine muscle. It is used to determine progress of LABOR, OBSTETRIC and assess status of pregnancy. It is also used in conjunction with FETAL MONITORING to determine fetal response to stress of maternal uterine contractions.Keratosis, Actinic: White or pink lesions on the arms, hands, face, or scalp that arise from sun-induced DNA DAMAGE to KERATINOCYTES in exposed areas. They are considered precursor lesions to superficial SQUAMOUS CELL CARCINOMA.Patents as Topic: Exclusive legal rights or privileges applied to inventions, plants, etc.Radiotherapy Planning, Computer-Assisted: Computer-assisted mathematical calculations of beam angles, intensities of radiation, and duration of irradiation in radiotherapy.Surgery, Plastic: The branch of surgery concerned with restoration, reconstruction, or improvement of defective, damaged, or missing structures.Hearing Loss, Unilateral: Partial or complete hearing loss in one ear.Burn Units: Specialized hospital facilities which provide intensive care for burn patients.Anesthesiology: A specialty concerned with the study of anesthetics and anesthesia.