The effects of high intensity light emissions, produced by a novel pulsed power energization technique (PPET), on the survival of bacterial populations of verocytotoxigenic Escherichia coli (serotype 0157:H7) and Listeria monocytogenes (serotype 4b) were investigated. Using this PPET approach, many megawatts (MW) of peak electrical power were dissipated in the ...

The effect of interpulse intervals on the perception of loudness of biphasic current pulse trains was investigated in eight adult cochlear implantees at three different stimulus levels encompassing the psychophysical dynamic range. Equal-loudness contours and thresholds were obtained for stimuli in which two biphasic pulses were presented in a fixed ...

Effects of 15 min light pulses given at various intervals (every 1, 2, 4, 6, 8 and 12 hr) under constant darkness on the locomotor rhythm were investigated in the adult male cricket, Gryllus bimaculatus. A single pulse per 24 hr induced period modulation in a circadian phase dependent manner, ...

We investigated the electrophysiological background for the waveform related variability of defibrillation efficacy. In 22 open-chest dogs, a localized potential gradient was created using an 8-V or 16-V field stimulus across a pair of plate electrodes separated by 5 mm. The post shock recovery interval of the nondepolarized myocardium adjacent ...

Attenuation coefficient and phase velocity measurements and direct optical observations showed that microbubbles of a contrast agent (Albunex) in 5% bovine albumin solution were not stable under ultrasonic irradiation. When the concentration of Albunex was 0.41 microL/mL and a 2.5-MHz phased array transducer of a Hewlett-Packard ultrasound imaging system (Model ...

The possibility of using a photodiode in the Geiger mode for timing of short light pulses is studied. It is found that the transit time between the light pulse and the electrical response is determined by a reliable exponential growth of electron and hole populations in the depletion layer from ...

Spread spectrum pulse compression is a signal processing algorithm that enhances critical system performance parameters such as signal-to-noise ratio, peak power requirements, minimum detectable signal, and total dynamic range. For this research, a digital, real-time, Barker coded, bi-phase modulator was designed and constructed, as well as a simple ultrasonic test ...

We sought to understand the excitation-contraction coupling process in arterioles. KCl or phenylephrine (PE) was applied via the superfusion solution or by brief pulsatile ejections from a micropipette onto unpressurized arterioles (in vitro) from either the guinea pig small intestine or hamster cheek pouch. With either mode of application, KCl ...

Experiments have been carried out to investigate the information transfer available via a single vibrator on the fingertip. In a first experiment, for stimuli with durations 80 to 320 ms, discrimination of a one-octave step change in frequency at the halfway point was investigated. Results were similar for three stimulus ...

This work details the design and implementation of a high-speed photography system for capturing events occurring during the laser-induced ablation of urinary calculi. New technology is presented in the form of a digital timing circuit driving a high-intensity light-emitting diode to provide the illuminating pulse for photography. Single events having ...

Many cochlear prostheses employ charge-balanced biphasic current pulses. These pulses have little energy at low frequencies resulting in limited stimulation of low frequency hearing by mechanical responses to the electrical stimulus. However, if electro-mechanical transduction within the cochlea is nonlinear, electrical stimulation with asymmetric, charge-balanced current pulses may result in ...

One of the sources of error in pulse oximetry readings is associated with an abnormal signal-to-noise ratio. The pulse oximeter distinguishes the light absorbance of arterial blood from that of other absorbers by differentiating between a constant component and a pulsating component. The pulsating component is almost exclusively the result ...

The phase-shift (delta phi) responses of the circadian rhythm in the field mouse Mus booduga to brief light pulses (LPs) of 15 minutes duration and 1000 lux intensity were measured in 90 experiments. In each experiment, a resetting light pulse LP1 was administered at CT14 (CT, circadian time), and a ...

The localized concentration of energy during a single bubble collapse is manifested in two forms, which are the emission of an acoustic pulse, and the emission of a light pulse. Through precise control of experimental parameters, one can levitate a single bubble in a standing wave field and measure the ...

I recorded the electric organ discharges (EODs) of 331 immature Brachyhypopomus pinnicaudatus 6-88 mm long. Larvae produced head-positive pulses 1.3 ms long at 7 mm (6 days) and added a second, small head-negative phase at 12 mm. Both phases shortened duration and increased amplitude during growth. Relative to the whole ...

Pulsed light is a non-thermal sterilization method that uses brief intense pulses or flashes of white light to kill micro-organisms. This article discusses tests performed on blow/fill/seal containers. The results suggest that pulsed light has potential as a terminal sterilization method for filled and sealed transmissive products and packages. It ...

A study was performed to assess the ability of pulsed light to sterilize water for injection in blow/fill/seal polyethylene containers. Pulsed light uses intense, short duration flashes of broad spectrum white light to produce high levels of microbial kill. In a first phase of testing, containers of 0.5, 5, 15, ...

STUDY OBJECTIVE: To compare the performance of five pulse oximeters during hypoperfusion, probe motion, and exposure to ambient light interference. DESIGN: Prospective study. SETTING: Laboratory facility at a university medical center. PATIENTS: 8 unanesthetized, ASA physical status I volunteers. INTERVENTIONS: We evaluated five common pulse oximeters with respect to three ...

Responses of auditory neurons in the torus semicircularis (TS) of Pleurodema thaul, a leptodactylid from Chile, to synthetic stimuli having diverse temporal patterns and to digitized advertisement calls of P. thaul and three sympatric species, were recorded to investigate their temporal response selectivities. The advertisement call of this species consists ...

This study estimated the mechanical response of the cochlea to pulsatile electrical stimulation of the scala tympani of the cat. The auditory nerve compound action potential evoked by an acoustic probe was forward-masked by a train of charge-balanced biphasic current pulses. Masking as a function of probe frequency reflected the ...

A 20-MHz passive acoustic detector was used to quantify the amount of transient acoustic cavitation occurring in a sample exposed to intense pulsed ultrasound. A dilute suspension of human erythrocytes with and without a microbubble echo-contrast agent was exposed in vitro to 500 W/cm2 (SPPA) ultrasound of center frequency 1 ...

The textured piezoelectric film of a new organic-based material produced by vapor deposition was used as an active element of a focusing ultrasonic transducer. The transducer exhibits near theoretical lateral and axial resolution, unipolar pulse response to a step voltage, and 30 dB insertion losses in an octave frequency band. ...

A novel method for the broadband absolute frequency synthesis of pulsed coherent lightwaves is demonstrated. It is based on pulse recirculation around an active optical feedback ring containing a delay-line fiber, an external phase modulator, an acousto-optic frequency shifter (AOFS), and a high-finesse Fabry-Perot étalon. The modulation frequency F(M) and ...

We demonstrate the use of a femtosecond pulse-shaping apparatus for electronically programmable phase filtering of amplified spontaneous emission from an erbium-doped fiber amplifier. Pulse shaping applied to a broadband incoherent light (noise) input results in reshaped noise, with a specially tailored electric field correlation function. Our experiments clearly reveal that ...

Phase shifts of the circadian rhythm of wheel-running activity were compared in Syrian hamsters maintained in constant darkness and exposed to 1-h naturalistic dawn or dusk twilight ramps (0.003-10 lx), or to 1-h rectangular light pulses (1 lx) providing equal photon exposure. The phase-response curves (PRCs) for dusk and rectangular ...

Two new technologies for use in the food industry are described. The first method discussed uses intense pulse of light. This pulsed light (PureBright) process uses short duration flashes of broad spectrum "white" light to kill all exposed microorganisms, including vegetative bacteria, microbial and fungal spores, viruses, and protozoan oocysts. ...

In this study it has been found that exposure of photosensitized erythrocytes to short, intense electric pulses, resulted in cell lysis. When erythrocytes were photosensitized with increasing concentrations of the photosensitizer, hematoporphyrin derivative (HPD), and subjected to electric pulses in the absence of light, cell lysis increased with increasing photosensitizer ...

The double cable model is used to investigate the electrotonic responses of the myelinated human motor nerve fibre to 100 ms depolarizing and hyperpolarizing current pulses. The model calculations provide estimates of the spatial and temporal distributions of the transaxonal and transmyelin components of the electrotonic potentials, both in different ...

The optimum setting for electromagnetic stimulation was examined by histologically assessing the degree of osteogenesis at different settings of electromagnetic stimulation, and comparing alkaline phosphatase (ALP) activity in the bone marrow. For this experiment, an electromagnetic field generator manufactured by the Institute of Physical and Chemical Research was used. The ...

We have characterized a reciprocating mechanical oscillation that can easily be detected in a large fraction of electrofused erythrocytes. Under our conditions, up to about 30% of all electrofusion products (e.g. doublet, triplet, and higher) show at least one cycle and up to 10% show only two cycles. A much ...

The sensory cues for a less known form of frequency shifting behavior, gradual frequency falls, of electric organ discharges (EODs) in a pulse-type gymnotiform electric fish, Rhamphichthys rostratus, were identified. We found that the gradual frequency fall occurs independently of more commonly observed momentary phase shifting behavior, and is due ...

Frequency doubling of a 680-nm laser diode in periodically poled LiTaO(3) is presented. By selective proton exchange followed by high-voltage pulse application, a second-order periodic domain inversion having uniform periodicity and optimum duty cycle was fabricated over a 10-mm interaction length in a 200-microm-thick LiTaO(3) substrate. A 340-nm wavelength of ...

1. We measured the modulation of the background firing rate of cat spinal motoneurons produced by simulated, repetitive excitatory postsynaptic potentials (EPSPs) to test the accuracy of several proposed motoneuron input-output functions. Rhythmic discharge was elicited in the motoneurons by injecting suprathreshold current steps 1-1.5 s in duration. On alternate ...

In this study we investigated the influence of red light< which naturally occurs during dawn and dusk, on locomotor activity and body temperature rhythms of Djungarian hamsters (Phodopus sungarus). A single weak red light pulse given 2 h before regular lights on had acute as well as long-term effects persisting ...

The electric fish Eigenmannia generates on oscillating weak electric field. The amplitude and timing information of this electric field is perceived by electroreceptors distributed on its skin. The pathway of timing information, consisting of spherical cells and giant cells, was studied in an in vitro preparation. The giant cells were ...

We describe audible and ultrasonic vocalization elicited in rats by a short electrical pulse applied to the tail. Three types of vocal emissions were recorded: (1) 'peep', characterized by a repartition of energy over a wide range (0-50 kHz) of frequencies without any clear structure; (2) 'chatters', characterized by an ...

Arterial pressure pulses are often measured noninvasively, but the influence of external recording forces has not been well documented. Accordingly, the main goal was to delineate pulse contour and amplitude distortion with progressively compressive forces applied to an external transducer. Ten young normal male subjects were studied while supine. Pulses ...

The relationship between variations in steady-state accommodation (microfluctuations) and rhythmic cycles in cardiopulmonary system was investigated. As previously reported, vascular pulse frequency was consistently correlated with the high frequency component of steady-state accommodation microfluctuations. In a new finding, respiration rate and an associated cycle in the instantaneous pulse rate also ...

Psychophysical detection of electrical stimulation of the cochlea was studied as a function of electrical-current configuration. Subjects were postlingually deaf humans with Nucleus 20 + 2, Nucleus 22, and Ineraid cochlear implants and nonhuman primates unilaterally deafened and implanted with a multielectrode array similar to the Nucleus implant. In nonhuman ...

An experimental and theoretical investigation of the temporal spread of an ultrashort light pulse on transmission through a highly scattering medium has been made. For the strongly diffuse light, the transmitted pulse may be described by a universal function whose duration can be directly related to the width of the ...

The perception of musical pitch was investigated in postlinguistically deaf subjects with cochlear implants. Stimuli consisted of sequences of biphasic electrical pulse trains at rates which represented the tones of the equal-tempered musical scale, delivered at equalized comfortable loudness levels to selected single bipolar electrodes along the array of the ...

The temporal profiles of ultrashort light pulses propagating through turbid media of different lengths were measured with a streak camera. Various Fourier spatial filters were used to select the spatial frequencies of the scattered pulses. The temporal profiles of the pulses scattered by a 0.4% Intralipid solution in a cell ...

The MFB substrate of self-stimulation (SS) has generally been viewed as a unilateral system. We re-examined this belief with pairs of moveable SS electrodes placed bilaterally in the MFB. Rats barpressed for trains of single or twin cathodal pulses of fixed intensity and width and of variable frequency. The first ...

Paired pulse stimulation of the perforant path provides a measure of inhibition of dentate granule cell field potentials that is reflected in the depression of the second (test) population spike (PS) relative to the first (conditioning) PS. The assumption that the strength of paired pulse depression is dependent upon the ...

Spatially resolved nonlinear scattering of a train of picosecond pulses from ethanol microdroplets is investigated. Different time behavior is observed for light with the same and the opposite sense of circulation as the input-coupled light. The forward-circulating light exhibits a smooth, delayed pulse-to-pulse growth, attributed to increased input coupling with ...

The double-burst-stimulation (DBS) is a new stimulation pattern developed to facilitate tactile evaluation of residual neuromuscular blockade. DBS consists of two bursts of high frequency stimulations separated by a short time interval. METHODS: By changing these components, the influence of 14 different DBS patterns on the relationship between the DBS ...

In this investigation, acoustic radiation force was used as a stimulus to determine the threshold for tactile perception in the human finger and upper forearm as a function of frequency and pulse duration. Initially, a small (1.8-cm2) acoustically reflecting disk was affixed to the anatomical exposure site to maximize the ...

Various factors, including variations in the concentration of hemoglobin, determine changes in the transparency of living tissue to near-infrared light. Hence, optical measures have been proposed as a noninvasive method for investigating regional changes in brain activity. However, the amount of near-infrared light traversing a region of the head is ...

Threshold exposures for producing intestinal hemorrhage in mice were determined using focused sources operating at 0.7, 1.1, 2.4 and 3.6 MHz. The choice of pulse length (10 microseconds) and pulse repetition frequency (100 Hz) made the exposures diagnostically relevant, while at the same time, minimized possible thermal contributions to the ...

1. The significance of particular acoustic properties of advertisement calls for selective phonotaxis by the gray treefrog, Hyla versicolor (= HV), was studied behaviorally and neurophysiologically. Most stimuli were played back at 85 dB SPL, a level typically measured at 1-2 m from a calling male. 2. Females preferred stimuli ...