101 - 125 of 129
Number of results to display per page
101 Normann, Richard A.; Shoham, ShyCoding of position by simultaneously recorded sensory neurones in the cat dorsal root ganglionMuscle, cutaneous and joint afferents continuously signal information about the position and movement of individual joints. How does the nervous system extract more global information, for example about the position of the foot in space? To study this question we used microelectrode arrays to record...Cats; Sensory Neurones; Movement; Limb Position2004
102 Christensen, Douglas A.Ultrasound beam propagation using the hybrid angular spectrum methodWe introduce a fast and accurate numerical method for simulating the propagation of an ultrasound beam inside inhomogeneous tissue for mapping beam absorption, refraction and diffraction in the body. The technique, called the hybrid angular spectrum method, is an extension of the angular spectrum m...Ultrasound beam propagation; Medical ultrasound; Inhomogeneous tissue; Beam simulation2008-08
103 Normann, Richard A.Control of retinal sensitivity. I. Light and dark adaptation of vertebrate rods and conesRods and cones in Necturus respond with graded hyperpolarization to test flashes spanning about 3.5 log units of intensity. Steady background levels hyperpolarize the rods, and the rod responses become progressively smaller as background level is increased. In cones, higher background levels reduce...Retina;Light and Dark Adaptation; Recepters; Bipolars; Ganglion Cells1974
104 Horch, Kenneth W.Intraspinal microstimulation using cylindrical multielectrodesA cylindrical multielectrode system specifically designed for intraspinal microstimulation was mechanically and electrically evaluated in the ventral horn of the feline lumbo-sacral spinal cord. Electrode insertions proved to be straight as evaluated from radiographs. Impedances were measured in s...Cylindrical multielectrode; Microstimulation; Neural prosthesis; Current distance constants; Electrode array; Spinal cord stimulation2006-02
105 Christensen, Douglas A.; Furse, Cynthia M.Problem and treatment of DC offsets in FDTD simulationsThis paper discusses the causes of and some solutions to the commonly observed problem of dc field offsets in finite-difference time-domain (FDTD) simulations. DC electric and magnetic field offsets are shown to be valid calculated responses of the modeled systems, resulting from interaction betwee...Finite-difference time-domain method; Direct current offsets; Waveforms2000-08
106 Horch, Kenneth W.Muscle recruitment with intrafascicular electrodesWe have studied muscle recruitment with Tefloninsulated, 25 pm diameter, Pt-Ir intrafasicular electrodes implanted in nerves innervating the gastrocnemius and soleus muscles of cats. The purpose of this study was to measure the performance of these bipolar electrodes, which had been designed to...Functional neuromuscular stimulation (FNS); Intrafascicular electrode1991
107 Christensen, Douglas A.Introduction to biomedical engineering: biomechanics and bioelectricity - part IIIntended as an introduction to the field of biomedical engineering, this book covers the topics of biomechanics (Part I) and bioelectricity (Part II). Each chapter emphasizes a fundamental principle or law, such as Darcy's Law, Poiseuille's Law, Hooke's Law, Starling's Law, levers and work in the...Bioelectricity; Kirchhoff's voltage law; Kirchhoff's current law; Coulomb's law; Thevenin equivalent circuits; Nernst potential; Matlab2009
108 Horch, Kenneth W.Identification of single units in multi-unit recordings from peripheral nervesWe are developing a computer-based method for identifying individual action potentials in multi-unit peripheral nerve recordings. Threshold level, sinusoidal stimuli are used to elicit phase-locked activity from single units. These action potentials are digitized, and a template is constructed usin...Peripheral nerve; Neural recordings; Cutaneous mechanoreceptors1988
109 Horch, Kenneth W.Selective stimulation of peripheral nerve fibers using dual intrafascicular electrodesWe have studied activation of newe fibers by pairs of Pt-Ir wire electrodes implanted within single fascicles of the nerve innervating the gastrocnemius muscle in cats. The purpose of this study was to determine if these intrafascicular electrodes can activate nerve fibers in different fascicles...Functional electrical stimulation; Intrafascicular stimulation; Silicon electrode array1993
110 Christensen, Douglas A.Multiple sensor optical thermometry system for application in clinical hyperthermiaThe thermometry system described is based upon the temperature dependence of the band edge absorption of infrared light in GaAs crystal. The design of the thermometry was completed, and the system was subjected to an extensive evaluation, including testing with tissue phantoms and microwave applic...Thermometry; Hyperthermia applicator; Phantom tests1984-01
111 Horch, Kenneth W.Microfabricated cylindrical multielectrodes for neural stimulationThe effects of spinal cord injuries are likely to be ameliorated with the help of functional electrical stimulation of the spinal cord, a technique that may benefit from a new style of electrode: the cylindrical multielectrode. This paper describes the specifications for, fabrication techniques for...Cylindrical multielectrode; Depth electrodes; Impedance testing; Microelectromechanical systems (MEMS); Microstimulation; Impedance testing; Neural prosthesis2006-02
112 Christensen, Douglas A.Plasma-etched polymer waveguides for intrachip optical interconnectsOptical intrachip communication offers the potential advantages of high speed and lack of electrical interference. We report on progress made on an interconnect design using GaAs LEDs, polymer waveguides, and photodiodes in a silicon substrate. The polymer waveguides are fabricated in polyimide or p...Polymer waveguides; Intrachip interconnects; LEDs1998
113 Varner, Michael W.; Clark, Edward B.; Fernando, Kumari L.; Mathews, V. JohnRobust estimation of fetal heart rate variability using Doppler ultrasound.This paper presents a new measure of heart rate variability (HRV) that can be estimated using Doppler ultrasound techniques and is robust to variations in the angle of incidence of the ultrasound beam and the measurement noise. This measure employs the multiple signal characterization (MUSIC) algori...Prenatal Ultrasonography; Fetal Heart Rate; Blood Flow Velocity; Algorithms2003-08
114 Gesteland, Raymond F.; Atkins, John F.; Weiss, Robert B.Slippery runs, shifty stops, backward steps and forward hops: -2, -1, +1, +2, +5 and +6 Ribosomal frameshiftingFrameshift mutations frequently express residual levels of gene activity; that is, they are often leaky. This leakiness can be used as a tool to define the functional components that affect the reading frame during gene expression. Recent technological advances in the capability to efficiently bu...Molecular Sequence Data; Mutation; RNA, Transfer; Frameshifting1987
115 Horch, Kenneth W.Intrafascicular electrodes for nerve stimulationWe have designed a new type of intrafascicular, implanted electrode for stimulating peripheral nerves to elicit muscle contraction. The electrode requires low current to stimulate the nerve fibers, provides a fine control of muscular force, and causes little or no tissue reaction. it is of potential...Intrafascicular electrodes; Peripheral nerve; Neural recordings1988
116 Christensen, Douglas A.; Herron, James N.Evanescent coupling in a waveguide fluoroimmunosensorA key factor in the analysis of evanescently-coupled optical sensors, such as the planar waveguide immunosensor analyzed here, is the efficiency of coupling between the optical waveguide modes and the fluorescent sources located on the surface of the waveguide. This is an important parameter in dete...Evanescent coupling; Waveguide; Fluoroimmunosensor1992
117 Horch, Kenneth W.Ontogeny of diving and feeding behavior in juvenile seaturtles: Leatherback Seaturtles (Dermochelys coriacea L) and Green Seaturtles (Chelonia mydas L) in the Florida CurrentWe compared activity, diving behavior and response to prey by Dermochelys coriacea and Chelonia mydas during their first 8-10 weeks of development.We reared juveniles in the laboratory and, at two-week intervals, released them in the ocean for a brief trial. Each turtle towed a device used to measur...Hatchlings; Posthatchling; Habitats2004
118 Normann, Richard A.; Muller, Jay F.; Kolb, HelgaSynaptic inputs to physiologically defined turtle retinal ganglion cellsTwo physiologically distinct, HRP-marked turtle retinal ganglion cells were examined for their morphology, GABAergic, glycinergic, and bipolar cell synaptic inputs, using electron-microscopic autoradiography and postembedding immunocytochemistry. One cell was a color-opponent, transient ON/OFF gangl...Turtles; Neural Pathways; Synapes; Retinal Ganglion Cells1991
119 Gesteland, Raymond F.Pattern of protein synthesis in monkey cells infected by simian virus 40After infection of several permanent monkey cell lines by simian virus 40 (SV40), four additional protein bands can be detected by simple sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell extracts. These bands appear only after the onset of viral deoxyribonucleic acid (DNA) syn...Monkeys; Simian virus 40; Peptides; DNA, Viral/biosynthesis1972
120 Horch, Kenneth W.Action potential classification with dual channel intrafascicular electrodesUsing recordings of peripheral nerve activity made with carbon fiber intrafascicular electrodes, we compared the performance of three different recording techniques (single channel, differential, and dual channel) and four different unit classification methods (linear discriminant analysis, temp...Carbon fiber intrafascicular electrodes; Dual channel recording1994
121 Christensen, Douglas A.; Horch, Kenneth W.Experience with the first three years of an accelerated dual-degree program in biomedical engineeringOur Department of Bioengineering has instituted a pilot program aimed at helping a select group of highly qualified students obtain both bachelor's and master's degrees in an accelerated timeframe-approximately four years from the beginning of their university studies. A key element of this progra...Accelerated; Dual-degrees; Education2004
122 Blumenthal, Donald K.; Underwood, Clayton J.Adaptation of the protein kinase filter paper assay to a 96-well microtiter format.The most widely used method for assaying protein kinase activities involves incorporation of radioactive phosphate into a protein or peptide substrate with subsequent binding or precipitaion of the radiolabeled substrate onto filter paper squares. We have adapted this assay for use with readily avai...Protein Kinase Activities; Filter Papers; Radioactive Phosphate1999-02-01
123 Christensen, Douglas A.Introduction to biomedical engineering: biomechanics and bioelectricity - part IIntended as an introduction to the field of biomedical engineering, this book covers the topics of biomechanics (Part I) and bioelectricity (Part II). Each chapter emphasizes a fundamental principle or law, such as Darcy's Law, Poiseuille's Law, Hooke's Law, Starling's law, levers and work in the a...Biological membranes; Poiseuille's law; Hooke's law; Starling's law of the heart; Matlab2009
124 Christensen, Douglas A.; Andrade, Joseph D.Improved sensitivity in ellipsometry of thin biochemical films by employing sublayersEllipsometry is widely used for investigating the optical properties of thin films on planar substrates, including films of adsorbed proteins or polymers. The average thickness and effective refractive index of the adsorbed layer are calculated by measuring the A and ¥ ellipsometry parameters. Unfo...Biochemical films; SiO2 sublayer1990
125 Horch, Kenneth W.; Normann, Richard A.Noble metal penetrating cortical stimulating electrode array: preliminary resultsElectrical stimulation of the visual cortex causes subjects to see spots of light (phosphenes) in their visual fields. We have developed arrays of penetrating electrodes which may from the basis of a visual prosthesis centered around electrical stimulation of the visual cortex. These arrays have bee...Visual prosthesis1988
101 - 125 of 129