Photoplethysmography: Plethysmographic determination in which the intensity of light reflected from the skin surface and the red cells below is measured to determine the blood volume of the respective area. There are two types, transmission and reflectance.Toes: Any one of five terminal digits of the vertebrate FOOT.Venous Insufficiency: Impaired venous blood flow or venous return (venous stasis), usually caused by inadequate venous valves. Venous insufficiency often occurs in the legs, and is associated with EDEMA and sometimes with VENOUS STASIS ULCERS at the ankle.Varicose Veins: Enlarged and tortuous VEINS.Fingers: Four or five slender jointed digits in humans and primates, attached to each HAND.Signal Processing, Computer-Assisted: Computer-assisted processing of electric, ultrasonic, or electronic signals to interpret function and activity.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Leg: The inferior part of the lower extremity between the KNEE and the ANKLE.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.Patents as Topic: Exclusive legal rights or privileges applied to inventions, plants, etc.Light: That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.Light Signal Transduction: The conversion of absorbed light energy into molecular signals.Phytochrome: A blue-green biliprotein widely distributed in the plant kingdom.Ultrasonography, Doppler: Ultrasonography applying the Doppler effect, with frequency-shifted ultrasound reflections produced by moving targets (usually red blood cells) in the bloodstream along the ultrasound axis in direct proportion to the velocity of movement of the targets, to determine both direction and velocity of blood flow. (Stedman, 25th ed)Ultrasonography, Doppler, Color: Ultrasonography applying the Doppler effect, with the superposition of flow information as colors on a gray scale in a real-time image. This type of ultrasonography is well-suited to identifying the location of high-velocity flow (such as in a stenosis) or of mapping the extent of flow in a certain region.Blood Flow Velocity: A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.Ultrasonography, Prenatal: The visualization of tissues during pregnancy through recording of the echoes of ultrasonic waves directed into the body. The procedure may be applied with reference to the mother or the fetus and with reference to organs or the detection of maternal or fetal disease.Pregnancy: The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH.Auscultation: Act of listening for sounds within the body.Blood Pressure Determination: Techniques for measuring blood pressure.Sphygmomanometers: Instruments for measuring arterial blood pressure consisting of an inflatable cuff, inflating bulb, and a gauge showing the blood pressure. (Stedman, 26th ed)Blood Pressure Monitors: Devices for continuously measuring and displaying the arterial blood pressure.Hypertension: Persistently high systemic arterial BLOOD PRESSURE. Based on multiple readings (BLOOD PRESSURE DETERMINATION), hypertension is currently defined as when SYSTOLIC PRESSURE is consistently greater than 140 mm Hg or when DIASTOLIC PRESSURE is consistently 90 mm Hg or more.Ulnar Artery: The larger of the two terminal branches of the brachial artery, beginning about one centimeter distal to the bend of the elbow. Like the RADIAL ARTERY, its branches may be divided into three groups corresponding to their locations in the forearm, wrist, and hand.Cellular Phone: Analog or digital communications device in which the user has a wireless connection from a telephone to a nearby transmitter. It is termed cellular because the service area is divided into multiple "cells." As the user moves from one cell area to another, the call is transferred to the local transmitter.Radial Artery: The direct continuation of the brachial trunk, originating at the bifurcation of the brachial artery opposite the neck of the radius. Its branches may be divided into three groups corresponding to the three regions in which the vessel is situated, the forearm, wrist, and hand.Mobile Applications: Computer programs or software installed on mobile electronic devices which support a wide range of functions and uses which include television, telephone, video, music, word processing, and Internet service.Vascular Patency: The degree to which BLOOD VESSELS are not blocked or obstructed.Text Messaging: Communication between CELL PHONE users via the Short Message Service protocol which allows the interchange of short written messages.Biomedical Engineering: Application of principles and practices of engineering science to biomedical research and health care.Forearm: Part of the arm in humans and primates extending from the ELBOW to the WRIST.Congresses as Topic: Conferences, conventions or formal meetings usually attended by delegates representing a special field of interest.Pharmacopoeias as Topic: Authoritative treatises on drugs and preparations, their description, formulation, analytic composition, physical constants, main chemical properties used in identification, standards for strength, purity, and dosage, chemical tests for determining identity and purity, etc. They are usually published under governmental jurisdiction (e.g., USP, the United States Pharmacopoeia; BP, British Pharmacopoeia; P. Helv., the Swiss Pharmacopoeia). They differ from FORMULARIES in that they are far more complete: formularies tend to be mere listings of formulas and prescriptions.International Cooperation: The interaction of persons or groups of persons representing various nations in the pursuit of a common goal or interest.United States Food and Drug Administration: An agency of the PUBLIC HEALTH SERVICE concerned with the overall planning, promoting, and administering of programs pertaining to maintaining standards of quality of foods, drugs, therapeutic devices, etc.Pressure: A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Transducers, Pressure: Transducers that are activated by pressure changes, e.g., blood pressure.Manometry: Measurement of the pressure or tension of liquids or gases with a manometer.Hydrostatic Pressure: The pressure due to the weight of fluid.Inventions: A novel composition, device, or process, independently conceived de novo or derived from a pre-existing model.Skin Pigmentation: Coloration of the skin.Epidermis: The external, nonvascular layer of the skin. It is made up, from within outward, of five layers of EPITHELIUM: (1) basal layer (stratum basale epidermidis); (2) spinous layer (stratum spinosum epidermidis); (3) granular layer (stratum granulosum epidermidis); (4) clear layer (stratum lucidum epidermidis); and (5) horny layer (stratum corneum epidermidis).Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Illusions: The misinterpretation of a real external, sensory experience.Tomography, Optical: Projection of near-IR light (INFRARED RAYS), in the 700-1000 nm region, across an object in parallel beams to an array of sensitive photodetectors. This is repeated at various angles and a mathematical reconstruction provides three dimensional MEDICAL IMAGING of tissues. Based on the relative transparency of tissues to this spectra, it has been used to monitor local oxygenation, brain and joints.Optical Fibers: Thin strands of transparent material, usually glass, that are used for transmitting light waves over long distances.Technetium Tc 99m Lidofenin: A nontoxic radiopharmaceutical that is used in RADIONUCLIDE IMAGING for the clinical evaluation of hepatobiliary disorders in humans.Elasticity: Resistance and recovery from distortion of shape.Pulse Wave Analysis: Evaluation of the contour of the PULSE waves which vary in different parts of the circulation and depend on physiological as well as pathophysiological conditions of the individual.Heart: The hollow, muscular organ that maintains the circulation of the blood.Myocardial Contraction: Contractile activity of the MYOCARDIUM.