Search Results
Results 451 - 500 of 950
< 5 6 7 8 9 10 11 12 13 14 15 >
Comtois Gary G Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA. - - 2007
Wearable physiological monitoring using a pulse oximeter would enable field medics to monitor multiple injuries simultaneously, thereby prioritizing medical intervention when resources are limited. However, a primary factor limiting the accuracy of pulse oximetry is poor signal-to-noise ratio since photoplethysmographic (PPG) signals, from which arterial oxygen saturation (SpO2) and heart ...
Peláez Eduardo Aguilar EA Department and Electronic Engineering, Imperial College London, London SW7 2AZ. - - 2007
The development of ambulatory arterial pulse oximetry is key to longer term monitoring and treatment of cardiovascular and respiratory conditions. The investigation presented in this paper will assist the designer of an ambulatory pulse oximetry monitor in minimizing the overall LED power consumption (P LED,TOT) levels by analyzing the lowest ...
Wong Kong-Fatt - - 2007
How do neurons in a decision circuit integrate time-varying signals, in favor of or against alternative choice options? To address this question, we used a recurrent neural circuit model to simulate an experiment in which monkeys performed a direction-discrimination task on a visual motion stimulus. In a recent study, it ...
Gholmieh Ghassan I GI Children Hospital Los Angeles, Division of Neurology, 4650 Sunset Blvd, MS 82, Los Angeles, CA 90027, USA. - - 2007
Screening for changes in the short-term plasticity (STP) characteristics induced by antiepileptic drugs (AEDs) can be accelerated using a novel in vitro bioassay. The bioassay is based on the analysis of varying population spike (PS) amplitudes recorded in the CA1 region of the hippocampal slice in response to Poisson distributed ...
Grapperhaus Michael J - - 2006
This paper presents the results of an initial investigation into using high-intensity incoherent light pulses to strip paint. Measurements of light pulse characteristics, the reflectivity of different paints and initial experiments on the threshold for paint removal, and paint removal are presented, along with an approximate model consistent with experimental ...
Montealegre-Z Fernando - - 2006
The calling song of an undescribed Meconematinae katydid (Tettigoniidae) from South America consists of trains of short, separated pure-tone sound pulses at 129 kHz (the highest calling note produced by an Arthropod). Paradoxically, these extremely high-frequency sound waves are produced by a low-velocity movement of the stridulatory forewings. Sound production ...
Chen Yong-Fan - - 2006
We have experimentally demonstrated that stored and retrieved light pulses have different frequencies but maintain phase coherence; a stored light pulse is released with a different polarization. However, the manipulation process causes an energy loss of the retrieved pulse. We have discovered that Clebsch-Gordan coefficients among the Zeeman sublevels play ...
Schreiber Ulrich - - 2007
A new phytotoxicity bioassay based on chlorophyll fluorescence imaging of algae suspensions in multiwell plates is introduced. Phytotoxicity is quantified via inhibition of photosystem II quantum yield, Y(II), assessed with the saturation pulse method. The basics of this approach as well as the factors enhancing and limiting its performance are ...
Karageorgou Panagiota - - 2007
The "saturating pulse" method of in vivo Chl fluorescence measurement has been widely used by physiologists and especially ecophysiologists, as it allows a simple, rapid and non-invasive assessment of PSII function and the allocation of absorbed energy into photochemical and non-photochemical processes. It is based on the accurate determination of ...
Janks Deborah L - - 2006
BACKGROUND: Experiments and clinical studies have shown that high-frequency (burst) pacing can induce reentry and fibrillation without a strong shock. We hypothesize that a train of weak stimuli induces quatrefoil reentry, and investigate the mechanism and threshold for this mode of reentry induction. METHODS: We apply a train of weak ...
Comas M - - 2006
To understand entrainment of circadian systems to different photoperiods in nature, it is important to know the effects of single light pulses of different durations on the free-running system. The authors studied the phase and period responses of laboratory mice (C57BL6J//OlaHsd) to single light pulses of 7 different durations (1, ...
Ward Alex R - - 2006
BACKGROUND AND PURPOSE: A randomized controlled trial to compare 2 forms of monophasic pulsed currents with 2 forms of burst-modulated, kilohertz-frequency alternating current ("Russian current" and "Aussie current") was conducted to establish whether different amounts of wrist extensor torque were produced and whether discomfort varied with stimulus type. SUBJECTS: The ...
Ikeda Teiichiro - - 2006
Cloud cavitation is potentially the most destructive form of cavitation. When the cloud cavitation is acoustically forced into a collapse, it has the potential to concentrate a very high pressure, more than 100 times the acoustic pressure, at its center. We experimentally investigate a method to control the collapse of ...
Omi Tokuya - - 2006
Phototherapy has become a treatment of choice in many areas of medicine. Light can deliver energy to tissue selectively, targeting specific structures in order to induce the desired therapeutic outcome. For the safe and effective removal of unwanted hair, the key optical parameters are wavelength, pulse duration and energy density, ...
Csomor Philipp A - - 2006
Prepulse inhibition (PPI) of the acoustic startle reflex is a translational behavioural paradigm for the assessment of sensorimotor gating deficit which has been demonstrated in a number of neuropsychiatric conditions. PPI refers to the reduction of the reflexive startle response to a 'pulse' stimulus when its presentation is shortly preceded ...
He Huijuan - - 2006
We have observed a dispersionlike absorption (or gain) spectrum at the D1 transition in a Rb vapor cell filled with a buffer gas, due to Zeeman coherence of the ground states in a double Lambda configuration. Meanwhile, we have also observed superluminal pulse propagation. It is experimentally demonstrated that the ...
Staud Roland - - 2006
Temporal summation of second pain or windup (WU(SP)) can be reliably evoked in normal human subjects by repetitive heat pulses to the skin at frequencies of 0.33 Hz or more. This phenomenon is dependent on activation of peripheral C-nociceptors and central N-methyl-D-aspartate receptors, resulting in windup of C-fiber-evoked discharges of ...
Shah Hassan A - - 2006
Information that defines the depth of activation of retinal neurons is useful in considering strategies for stimulation with a retinal prosthesis, or interpreting the results from human studies that have previously been performed. The purpose of this study was to test the assertion that electrical pulse durations >0.5 msec preferentially ...
Accarino A M - - 2006
Intestinal sensitivity can be tested using transmucosal electrical nerve stimulation. The aim of this study was to establish the stimulus characteristics that determine perception. In six healthy subjects constant current electrical stimuli were applied via an intrajejunal bipolar electrode while measuring perception. Intensity-response tests with stimuli trains of various frequencies ...
Macherey Olivier - - 2006
Existing cochlear implants stimulate the auditory nerve with trains of symmetric biphasic (BP) pulses. Recent data have shown that modifying the pulse shape, while maintaining charge balance, may be beneficial in terms of reducing power consumption, increasing dynamic range, and limiting channel interactions. We measured thresholds and most comfortable levels ...
Fine Michael S - - 2006
Although previous experiments have identified that errors in movement induce adaptation, the precise manner in which errors determine subsequent control is poorly understood. Here we used transient pulses of force, distributed pseudo-randomly throughout a movement set, to study how the timing of feedback within a movement influenced subsequent predictive control. ...
Miller Charles A - - 2006
Nearly all studies on auditory-nerve responses to electric stimuli have been conducted using chemically deafened animals so as to more realistically model the implanted human ear that has typically been profoundly deaf. However, clinical criteria for implantation have recently been relaxed. Ears with "residual" acoustic sensitivity are now being implanted, ...
Takada Hideyuki - - 2006
We demonstrate the direct generation of 12 fs pulses from a Ti:sapphire regenerative amplifier system at a 1 kHz repetition rate utilizing properly designed broadband components for chirped-pulse amplification. Optimized designs of a regenerative amplifier with a multilayer gain-narrowing compensator and an adaptive dispersion compensator with a spatial light modulator ...
Ghose Kaushik - - 2006
Adaptive behaviors require sensorimotor computations that convert information represented initially in sensory coordinates to commands for action in motor coordinates. Fundamental to these computations is the relationship between the region of the environment sensed by the animal (gaze) and the animal's locomotor plan. Studies of visually guided animals have revealed ...
Parsons Jessica E - - 2006
Methods were investigated to acoustically control the extent to which cavitation-mediated tissue homogenization is responsible for lesion formation in vitro. These results may guide potential therapeutic procedures that induce damage predominantly via mechanical disruption and, thereby, avoid limitations associated with thermal ablative modalities. Porcine myocardium was insonified at 750 kHz ...
Kawauchi Satoko - - 2006
Although photodynamic therapy with pulsed light excitation has interesting characteristics, its photosensitization mechanism has not been fully elucidated. In this study, we showed that the intracellular kinetics of ATX-S10.Na(II), a lysosomal sensitizer, was closely related to photochemical reaction dynamics during photodynamic treatment of A549 cells with nanosecond pulsed light. Fluorescence ...
Ammi Azzdine Y AY Laboratoire d'Imagerie Paramétrique, UMR 7623 C.N.R.S., 75006 Paris, - - 2006
Determining the rupture pressure threshold of ultrasound contrast agent microbubbles has significant applications for contrast imaging, development of therapeutic agents, and evaluation of potential bioeffects. Using a passive cavitation detector, this work evaluates rupture based on acoustic emissions from single, encapsulated, gas-filled microbubbles. Sinusoidal ultrasound pulses were transmitted into weak ...
Wu Pengfei - - 2005
We observe that the group velocity of light is reduced to an extremely low value of 0.091 mm/s in a biological thin film of bacteriorhodopsin at room temperature. By exploiting unique features of a flexible photoisomerization process for coherent population oscillation, the velocity is all-optically controlled over an enormous span, ...
Stenner Michael D - - 2005
We describe a methodology to maximize slow-light pulse delay subject to a constraint on the allowable pulse distortion. We show that optimizing over a larger number of physical variables can increase the distortion-constrained delay. We demonstrate these concepts by comparing the optimum slow-light pulse delay achievable using a single Lorentzian ...
Ishizuka Toru - - 2006
Neurons become photosensitive by genetically introducing one of green algae-derived protein, channelrhodopsin-2 (ChR2). Here, we quantitatively investigated the rapidness of the light-gated current of ChR2 expressed in PC12 cells using blue light-emitting diode (LED) light. The light-gated current consists of two components, inactivating and non-inactivating. The magnitude of inactivating component ...
Schor Clifton M - - 2006
Dynamic properties and control strategies of step responses by accommodation and disaccommodation differ from one another. Peak velocity of accommodation increases with response magnitude, while peak velocity and peak acceleration of disaccommodation increase with starting position. These dynamic properties can be modeled as control strategies that use independent acceleration-pulse and ...
Bau Josep - - 2005
Trains of 20-ms-duration pulses of pheromone were delivered at rates of 1-33 Hz to antennal preparations of males of Bombyx mori and Lymantria dispar, two moth species with bipectinate antennae. Resolution of rapidly pulsed plumes of pheromone was not compromised by a complex antennal morphology or by moderate changes in ...
Donnelly Ronald F RF Msc Chem Bsc - - 2005
Fentanyl is a potent synthetic lipophilic opiate agonist used to control pain as a single agent or in combination with local anesthetics. The chemical stability of the undiluted commercial solution (50 micrograms/mL) in polypropylene syringes or polyvinylchloride bags has never been reported. Undiluted fentanyl solution, 50 micrograms/mL, was aseptically transferred ...
Canal M M - - 2006
Circadian rhythms of animals are reset by exposure to light as well as dark; however, although the parameters of photic entrainment are well characterized, the phase-shifting actions of dark pulses are poorly understood. Here, we determined the tonic and phasic effects of short (0.25 h), moderate (3 h), and long ...
Fried S I - - 2006
The goal of retinal prosthetic devices is to generate meaningful visual information in patients that have lost outer retinal function. To accomplish this, these devices should generate patterns of ganglion cell activity that closely resemble the spatial and temporal components of those patterns that are normally elicited by light. Here, ...
Reynolds N - - 2005
The pulsed dye laser has been the treatment of choice for port wine stains over the past 20 years. In the past 5 years there has been increasing discussion of the role of other light treatments, such as the intense pulsed light system in the treatment of port wine stains. ...
Summers lan R - - 2005
Two experiments on the discrimination of time-varying tactile stimuli were performed, with comparison of stimulus delivery to the distal pad of the right index finger and to the right wrist (palmar surface). Subjects were required to perceive differences in short sequences of computer-generated stimulus elements (experiment 1) or differences in ...
Yee Benjamin K - - 2005
Using the acoustic startle reflex, prepulse inhibition (PPI) is typically demonstrated by the interaction between two auditory stimuli presented in close temporal proximity. When a startle-eliciting pulse stimulus is shortly preceded by a weak prepulse stimulus, the reaction to the former is attenuated in comparison to when the pulse stimulus ...
Holt Rachael Frush - - 2005
N. F. Viemeister and G. H. Wakefield's (1991) multiple looks hypothesis is a theoretical approach from the psychoacoustic literature that has promise for bridging the gap between results from speech perception research and results from psychoacoustic research. This hypothesis accounts for sensory detection data and predicts that if the "looks" ...
Carlyon Robert P - - 2005
Human behavioral thresholds for trains of biphasic pulses applied to a single channel of Nucleus CI24 and LAURA cochlear implants were measured as a function of inter-phase gap (IPG). Experiment 1 used bipolar stimulation, a 100-pps pulse rate, and a 400-ms stimulus duration. In one condition, the two phases of ...
Tortoli Piero - - 2005
In flow measurements in which microbubbles are involved, the amplitude and phase of the received echo signal are noticeably influenced by the transmitted ultrasound intensity. Previous studies have shown that, when such intensity is progressively increased, the Doppler spectrum is accordingly distorted, i.e., it is asymmetrically broadened toward the negative ...
Weill Rafi - - 2005
Light is shown to exhibit critical and tricritical behavior in passively mode-locked lasers with externally injected pulses. It is a first and unique example of critical phenomena in a one-dimensional many-body light-mode system. The phase diagrams consist of regimes with continuous wave, driven parapulses, spontaneous pulses via mode condensation, and ...
Chatterjee Dhiman - - 2005
Broadband attenuation measurement has been widely used for characterizing ultrasound contrast agents. Chen et al. (2002) recently suggested that broadband attenuation data depend on the center frequency of the broadband excitation pulse and, therefore, that they are not a reliable measure of the bubble behavior. We investigated the suitability of ...
Yamagiwa Masatomo - - 2005
We observed a propagating femtosecond light pulse train generated by an integrated array illuminator as a spatially and temporally continuous motion picture. To observe the light pulse train propagating in air, light-in-flight holography is applied. The integrated array illuminator is an optical device for generating an ultrashort light pulse train ...
Li Songhai - - 2005
This paper describes the high-frequency echolocation signals from free-ranging Yangtze finless porpoise in the Tian-e-zhou Baiji National Natural Reserve in Hubei Province, China. Signal analysis showed that the Yangtze finless porpoise clicks are typical high-frequency narrow-band (relative width of the frequency spectrum Q = 6.6 +/- 1.56, N = 548) ...
Nourski Kirill V - - 2005
This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in ...
van Oostrom Johannes H - - 2005
Interference on pulse oximetry can come from many sources. We found an additional source of interference from the Stealth Station. This article gives an overview of sources of pulse oximeter interference so that clinicians can better prevent them. Technical features: This article discusses the infrared disturbances caused by the Stealth ...
Hernandez Ruben V - - 2005
Theta-burst stimulation (TBS: four pulses at 100 Hz repeated with 200 ms inter-burst-intervals) and another commonly used high-frequency stimulation protocol (HFS: 1 s burst of equally spaced pulses at 100 Hz) were compared for the magnitude of LTP produced in rat hippocampal slices. The total number of pulses applied during ...
Irwin William P - - 2005
Loggerhead sea turtles (Caretta caretta) derive both directional and positional information from the Earth's magnetic field, but the mechanism underlying magnetic field detection in turtles has not been determined. One hypothesis is that crystals of biogenic, single-domain magnetite provide the physical basis of the magnetic sense. As a first step ...
Bloch Susannah H - - 2005
In this technical note, we study three polymer-shelled microbubble contrast agents manufactured by POINT Biomedical Corporation that have identical shell composition and mean volumetric diameters of 0.74 microm, 0.91 microm and 1.33 microm. We investigate the effect of agent size on the amplitude, frequency and probability of acoustic echoes received ...
< 5 6 7 8 9 10 11 12 13 14 15 >