In this study, the threshold for subharmonic emission during in vivo sonication of rabbit brain was investigated. In addition, the histologic effects of pulsed sonication above this threshold were studied. Two spherically curved focused ultrasound transducers with a diameter of 80 mm and a radius of curvature of 70 mm ...

It is shown that by varying the space distribution of the pulse before the focusing lens it is possible to control the temporal shape of the pulse in the focal plane. The consideration is based on representation of the light pulse as a superposition of Bessel or nondiffracting beams. The ...

Experimental studies have recently demonstrated that fluorescence emission can be quenched by laser light pulses from modern high-repetition rate lasers, a phenomenon we call "light quenching." In this overview article, we describe the possible effects of light quenching on the steady-state and time-resolved intensity and anisotropy of fluorophores. One can ...

The goal of the study was to compare pulse responses with sinusoidal temporal responsivity. The response of macaque ganglion cells was measured to brief luminance and chromatic pulses and to luminance or chromatic sinusoidal modulation. To make both positive and negative lobes of the pulse response visible, responses to pulses ...

The purinergic response of the guinea-pig vas deferens to long trains of pulses at high frequency consists of an initial twitch followed by a much lower plateau. Mechanical, neurochemical and electrophysiological techniques were used to examine the reason for the fade. Mechanical measurements. In tissues stimulated by trains of 180 ...

Experimental studies have recently demonstrated that fluorescence emission can be quenched by laser light pulses from modern high repetition rate lasers, a phenomenon we call "light quenching." We now describe the theory of light quenching and some of its effects on the steady-state and time-resolved intensity and anisotropy decays of ...

The second harmonic of a femtosecond Ti:sapphire regenerative amplifier system is used to pump parametric generator-amplifier producing visible light pulses of 160-fs duration near 570 nm and infrared pulses of < 100-fs duration between 1.23 and 1.45 µm.

BACKGROUND AND PURPOSE: The purposes of this investigation were to determine the effect of five commonly used voltage waveforms (four pulsed and one sinusoidal) on excitation of sensory and motor nerves and to characterize variables associated with reaching threshold. SUBJECTS: Eighteen healthy subjects were stimulated during one session via surface ...

An exposure system producing interleafed pulses of 1-MHz ultrasound from balanced, opposing transducers was used to test the bubble recycling hypothesis (as formulated with respect to rotating exposure vessels) in a stationary exposure vessel containing P388 cell suspensions. Cell lysis was measured in cell suspensions which had been exposed or ...

The electrical self-stimulation paradigm has proven to be very useful in research aimed at delineating the neural substrates involved in reward-related learning. Of the procedures currently employed the curve-shift method is among the more useful since it distinguishes between treatment effects on reward and performance. This method involves generating and ...

1. In these experiments we assess the relative importance of the spatial and temporal properties of a moving tactile stimulus in determining the ability of humans to discriminate its direction of motion. Movement along the finger was simulated by applying a series of pulses to adjacent locations on the skin ...

The perception of temporal acoustic patterns was studied in the goldfish using classical respiratory conditioning in combination with a stimulus generalization paradigm. Stimuli consisted of a bandpass filtered pulse repeated in various periodic and aperiodic temporal patterns. In each of 14 experiments, animals received 40 conditioning trials to a given ...

A hypothesis was proposed that bats employing frequency-modulated (FM) echolocation pulses could utilize dynamic information of a flying insect to discriminate prey on the basis of "stroboscopic hearing." To test this hypothesis, single unit recordings were made from the inferior colliculus (IC) of the little brown bat, Myotis lucifugus. Response ...

The acute and residual entraining effects of a 15 min pulse of light on rat pineal function in individual animals were investigated using the excretion rate of the melatonin metabolite, 6-sulphatoxymelatonin, as an index of melatonin production. In animals maintained in a 12-hr L:12-hr D photoperiod (lights off 1800), 15 ...

1. Ferret papillary muscles were magnetically stimulated by the discharge of a capacitor through an inductance. 2. An induced current density of 39 mA cm-2 averaged over 280 microseconds (= 11 microC cm-2) corresponded to threshold. 3. A short galvanic current pulse was found to have a comparable charge threshold. ...

Photorefractive properties of a cerium-doped strontium barium niobate single crystal (Sr(0.61)Ba(0.39)Nb(2)O(6)) are investigated with Q-switched light pulses (wavelength 532 nm). Pyroelectric fields are the dominant charge driving force and significantly enhance light-induced refractive-index changes.

Pulsed fluoroscopy (hereafter called pulsed) at reduced acquisition rates, typically 15 acq/s (pulsed-15), is proposed to reduce x-ray dose in interventional procedures. However, since the human visual system (HVS) acts as a temporal low-pass filter that interacts with such acquisitions, the proper dose for pulsed must be obtained in perception ...

Eighty-five ultrasound therapy machines in use in Lothian Region, Scotland were tested for performance and their recalibration was expedited where necessary. The performance characteristics reported are the temporal average acoustic output power, the treatment frequency, pulse timing and treatment timer accuracy. Consideration is also given to the performance of the ...

Exposure conditions were determined for hind limb paralysis and lung hemorrhage of neonatal mice due to pulsed exposure (10 microsecond pulse duration) to 1 MHz focused ultrasound. Spatial peak pulse average intensity and peak rarefactional pressure levels for paralysis in 50% of specimens sonicated were determined for pulse repetition frequencies ...

Normal subjects exerted isometric torque at a rapid rate of contraction with different amplitude targets, and at different rates with a constant target. In the fastest contractions, the agonist triceps and antagonist biceps muscles showed an electromyographic volley characterized by a slow wave with an initial negative and subsequent positive ...

Differential absorption has been detected and localized in three-dimensions by recording the photoacoustic pulses that were produced when short-duration (approximately 1 microsecond) pulses of electromagnetic energy were absorbed regionally within a turbid medium. These absorption sites were localized with a spatial resolution of approximately 6 mm within a 20 x ...

This method can be applied to the non-drug treatment of diseases. It provides an exact evaluation of the healing effect by keeping the acupuncture point from overload. This method is realized by a bistable/monostable square wave oscillator. The electrical pulses for the treatment of the acupuncture point are delivered from ...

Complex vocal responses in both the audible and ultrasonic frequency ranges were elicited by a single 2 ms electrical pulse applied to the tail. The first two cries exhibited consistent latencies and durations, were intensity-dependent and were triggered by peripheral fibres with conduction velocities of 7.3 +/- 0.8 and 0.7 ...

A new technique for determining the complex electric field of an ultrashort light pulse is analyzed and experimentally demonstrated. It is based on the measurement of the spectrally resolved intensity autocorrelation and an iterative procedure of data deconvolution. This method is shown to be convenient and reliable.

Precipitous increases in multi-unit electrical activity (MUA volleys) can be recorded from the mediobasal hypothalamus of the rhesus monkey that are invariably synchronous with the initiation of luteinizing hormone (LH) pulses and thus serve as markers of gonadotrophin releasing hormone (GnRH) pulse generator activity. Continuous radiotelemetric monitoring of this activity ...

In the course of previous studies using continuous monitoring of the electrophysiological correlates of GnRH pulse generator activity, characterized by episodic increases in hypothalamic multiunit electrical activity (MUA volley), it was noticed that the nocturnal slowing of pulse generator frequency was an acute phenomenon observable in the first MUA volleys ...

Psychophysical detection thresholds for electrical stimulation of the cochlea were measured in nonhuman primates (macaques) as part of a series of experiments exploring the stimulus features affecting detection. The monkeys were trained psychophysically using operant conditioning. One ear was treated with neomycin to destroy hair cells, and implanted with electrodes ...

Oximetry nowadays is understood as the in vitro measurement of O2 saturation (sO2, %) and hemoglobin (Hb) derivatives (%) using 4-7 wavelengths (CO- and Hem-oximeters). Pulse oximeters, using only 2 wavelengths, are designed for the continuous noninvasive measurement of the arterial partial O2 saturation (psO2, %) in vivo. Light-emitting diodes ...

Field crickets are interesting models for study of auditory phenomena because they solve many of the same acoustic problems as humans, but with simpler nervous systems. Previous work in this lab and others has investigated sound localization, frequency and temporal pattern discrimination, habituation and dishabituation, and categorical perception. This paper ...

The perception of temporal modulations of pulsatile electric stimuli was measured in seven cochlear implant patients using the Cochlear Pty. Limited prosthesis. Four patients were postlingually deafened adults and three patients were young adults who were deafened very early in life. The first study measured detection thresholds for modulated pulse ...

The duration of the conventional caloric stimulus is too long and the termination of the stimulus is uncontrolled. This study explores the use of a brief terminal "washout" irrigation pulse at 37 degrees C which is intended to 1. shorten the duration of action of the caloric stimulus and 2. ...

(1) Skinned fibres from rat psoas muscle were placed in oil and activated at 10 degrees C by pulse photolysis of caged ATP. From the force and stiffness transients on small ATP pulses, we estimated the concentration and rate of ATP hydrolysis of the crossbridges in the fibres. They were ...

Temporal and digital pulse amplitudes, forehead temperature, heart rate, respiration rate and electrodermal activity of 37 migraine patients and 37 matched controls from a population of psychology students were recorded during three experimental sessions: adaptation, real-life stress (an examination) and experimental stress (an IQ test). Migraine sufferers showed significantly smaller ...

Detection thresholds for biphasic symmetric pulses were measured in fourteen human subjects implanted with the Cochlear Corporation Nucleus 22 Implant. The effects of phase duration on thresholds were studied using single pulses, and 500 ms pulse trains at 100 pps. Psychophysical detection thresholds decreased as a function of phase duration ...

The supercontinuum light generated by oblique intense 100-fs ultrafast laser pulses was found to bend from the direction of the incident pulses. The emission direction of the anti-Stokes continuum that is due to self-phase modulation bends to one side, while the conical ring that is due to four-photon parametric generation ...

Focusing of ultrashort light pulses with single lenses is analyzed by taking into account the unavoidable interplay between chromatic and spherical aberration simultaneously for the first time to our knowledge. The spatial intensity distribution is mainly affected by spherical aberration, whereas the temporal distribution is determined by both aberrations. The ...

The rotating frame of localized spectroscopy can be augmented by the inclusion of a refocusing pulse to enable the measurement of T2 relaxation times. This technique is particularly appropriate for determining short relaxation parameters due to the absence of time consuming switched B(omicron) field gradients. We have evaluated the accuracy ...

Membrane damage resulting from ultrasonic gas body activation was investigated in leaves of the aquatic plant Elodea using pulse-mode exposures from 0.745-15 MHz. The frequency response was similar to that previously observed for continuous exposures. Cell death thresholds were higher for the pulse modes; for example, at 6 MHz the ...

The function relating electrical self-stimulation (ESS) bar-pressing rate to the frequency of cathodal pulses (0.2 mA and 0.1 ms) was obtained for several positions of a movable electrode in the dorsal diencephalon of the rat. The rate-frequency functions were fitted to a sigmoid model to obtain the asymptotic rate and ...

The influence of electrical stimulus parameters on focal seizure production was studied. Stimulations and recordings were carried out with bipolar electrodes stereotactically positioned in the ventral hippocampus of kindled rats. After discharge thresholds were determined for stimulus trains with different combinations of train durations (0.5, 1, 2, 5, 10 s), ...

Ultrasonic vocalizations of flying bats were effectively monitored with radiotelemetry. We describe a device light enough to be carried by an 11 g bat for periods of up to 1 h. It transmitted signals adequate for fine frequency analysis within a range of approximately 3 m. Telemetry permitted the recording ...

1. The Jamaican mustached bat uses a biosonar signal (pulse) with eight major components: four harmonics each consisting of a long constant frequency (CF1-4) component followed by a short frequency-modulated (FM1-4) component. While flying, the bat adjusts the frequency of its pulse so as to maintain the CF2 of the ...

The cw, interpulse, and intrapulse frequency stabilities of a compact, sealed-off CO(2) Doppler lidar transmitter are characterized. A cw stability of 1 part in 5 x 10(11) for 1-s averaging times, maximum pulse-to-pulse frequency deviations of +/-49 kHz for periods of seconds at a pulse repetition frequency of 1 kHz, ...

Effects of pulse width on discrimination of simultaneous changes in frequency and level of electrical pulse trains were studied in a monkey subject with a cochlear implant. At test-stimulus levels where performance was minimum, frequency difference limens were larger for longer-duration pulses than that for shorter-duration pulses. Several factors may ...

1. The purpose of this study was to study the effects of a high-frequency burst of pulses at the onset of a subtetanic train of pulses on the force output of the rat soleus muscle. 2. The soleus muscle was studied in eight rats deeply anesthetized with urethan. The effects ...

A new technique for the external frequency translation of light waves is proposed. The technique enables the stepwise sweeping of an optical frequency in time over a wide range. The frequency translator is composed of an optical pulse modulator and an optical ring circuit that contains an acousto-optic frequency shifter ...

In the present study, we have demonstrated hysteresis phenomena in the excitability of single, enzymatically dissociated guinea pig ventricular myocytes. Membrane potentials were recorded with patch pipettes in the whole-cell current clamp configuration. Repetitive stimulation with depolarizing current pulses of constant cycle length and duration but varying strength led to ...

Precise measurements of the minimal fluorescence yield (F(o)) and maximal fluorescence yield (F(m)) of a dark-adapted sample are prerequisites for the quantification of other fluorescence parameters. The pulse amplitude-modulated chlorophyll fluorometer (PAM 101 Chlorophyll Fluorometer, Heinz Walz, Effeltrich, Germany) and saturating pulse technique have frequently been used in measuring F(o) ...

Continuous pure-tone stimuli are traditionally used for contralateral acoustic reflex threshold (ART) testing. The GSI-33 middle ear analyzer provides an option of pulsed stimuli for contralateral ART testing. This study compared ARTs for the steady and the pulsed stimuli for 100 ears. Lower ARTs were consistently obtained with the continuous ...

A new method to measure the dynamic range of electrotactile (electrocutaneous) stimulation uses both steepest ascent (gradient) and one-variable-at-a-time methods to determine the waveform variables that maximize the subjective magnitude (intensity) of the electrotactile percept at the maximal current without discomfort for balanced-biphasic pulse bursts presented at a 15-Hz rate. ...