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Results 551 - 600 of 643
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Rigney D R - - 1989
When excessive fluid accumulates in the pericardial space, the heart, suspended by the great vessels, is then free to swing as a pendulum. The swinging may occur at either the same frequency as the heart rate (1:1 oscillation) or at half the heart rate (2:1 oscillation), the latter frequency often ...
Donnerstein R L - - 1989
Severity of stenotic heart lesions affects timing, quality and pitch of associated heart murmurs. This quantitative study investigated the relation between instantaneous sound frequencies contained in heart murmurs and magnitudes of Doppler jet velocities measured distal to associated obstructions. Heart murmurs were recorded from 18 patients, ages 1 day to ...
Beuter A - - 1989
Experiments were performed to investigate the oscillations arising in a human motor system with delayed visual feedback. Eight subjects were instructed to maintain a constant finger position relative to a stationary baseline. The finger displacement was measured using a microdisplacement transducer connected to the index finger, and was displayed on ...
Johnen M - - 1989
EEG arousal and heart rate responses to change in tone frequency following habituation training were studied during slow wave sleep in the rat. Rats were exposed to sequences of 12 tone pulses. Habituation stimuli (trials 1-7) had a frequency of 16 kHz. The frequency of the following (test) trials was ...
Brown D R - - 1989
The purpose of this experiment was to test the stability of the heart rate (HR) power spectrum over time in conscious dogs. HR was recorded for 1 h for each of six animals on 2 days. A Fast Fourier transform was used to derive the HR power spectrum for the ...
Mazgalev T - - 1989
The well-known paradoxic behavior of atrioventricular conduction, the so-called gap phenomenon, that occurs when impulses within a certain range of coupling intervals are blocked while impulses with shorter coupling intervals are conducted is attributed to differences in properties of refractoriness in neighboring regions of the conduction system. In contrast, in ...
Southard D - - 1989
The purpose of this study was to determine the nature and effect of certain highly patterned behaviours utilized prior to free-throw shooting in basketball. Ten female basketball players comprising the varsity squad of Texas Christian University, Fort Worth, Texas, USA served as subjects for this study. Subjects were filmed with ...
Weise F - - 1989
The experiments were carried out to study the influence (a) of 3 different respiratory frequencies (0.12, 0.20 and 0.35 Hz) on heart rate power spectra during orthostatic load with special reference to the peak frequency of mid-frequency heart rate fluctuations, and (b) of variation in respiratory depth on this peak ...
Misslin R R Laboratoire de Paychophysiologie, 7 rue de l'Université, 67000 Strasbourg, - - 1989
In order to teat the behavioural value of a two-chambered light/dark choice procedure used for pharmacological studies, we investigated the effects of several internal and external factors on two variables: the time spent by mice in the lit box (TLB) and the number of transitions between the lit box and ...
Saul J P - - 1989
An efficient new technique was developed to investigate heart rate control at all physiologically relevant frequencies by using respiratory activity as a frequency probe of the autonomic nervous response. The transfer function from respiratory activity to heart rate was determined during 6-min periods in which the respiratory rate was voluntarily ...
Kawahara K - - 1989
Spectral analysis was performed on the fluctuation in respiratory intervals in vagotomized, paralyzed, and unanesthetized decerebrate cats. The respiratory interval was measured as the time interval between the onset of phrenic neural activity. When endtidal PCO2 was set at the same level as that before immobilization, the power spectral densities ...
Witte H - - 1988
Within the fluctuations that occur in heart rate, there is a major component known as respiratory sinus arrhythmia (RSA), which up to now has been defined as heart rate variability which is synchronous with respiratory movements. We have now discovered that RSA synchronous to respiratory movements is only one example ...
Warner M R - - 1988
The beat-by-beat changes in atrioventricular (AV) conduction evoked by constant frequency and phase-coupled vagal stimulation were examined both qualitatively and quantitatively in 13 anesthetized dogs. The effects of pacing cycle length and sympathetic activity on the vagally induced phasic changes in AV conduction were also characterized. When the vagal stimulus ...
Prochazka A - - 1988
1. Frequency-modulated vibration was applied to the elbow flexor and extensor tendons to produce reflex movements of the forearm in normal subjects. The modulating (command) signal caused equal and opposite deviations from the 40 Hz carrier frequency so that when flexor vibratory frequency increased, extensor frequency decreased, and vice versa. ...
Jacks A - - 1988
1. Amplitude-modulated electrical stimulation was applied to the elbow flexors and extensors to produce movements of the forearm in normal subjects. The parameters of the modulating (command) signal were set in isometric trials so as to produce equal and opposite background torques, and equal and supportive torque modulations. 2. Bode ...
Forgays D G - - 1988
The present study investigates the effect of spatial orientation of the body on heart rate during conditions of water-immersion sensory isolation. Two groups of three men and three women each were exposed to one of two isolation conditions. In one condition the subject was suspended in a buoyant but vertical ...
Mussivand T - - 1988
The purpose of the study was to characterize flow properties within a clinical pusher plate type artificial heart. Dual camera video tape and synchronized still photographs were used to study flow patterns. Diffused light and a planar laser source provided illumination. The laser light was turned into a plane of ...
Gonzalez Gonzalez J - - 1988
The beat-to-beat heart rate of the lizard, Gallotia galloti, at rest shows short-term oscillations, the frequency of which varies with body temperature. Spectral analysis of the heart rate variability signal shows that, above 20 degrees C, two major frequency components are present: the first component has a mean frequency ranging ...
Timmis G C - - 1988
The morphology of bipolar electrograms recorded in the right atrium was examined in nine patients in an attempt to discriminate retrograde from anterograde atrial signals to an extent that would be useful for physiologic pacing. Peak-to-peak amplitude, duration, square root of energy (energy), maximum slew rate, mean slew rate, and ...
Rosen M R - - 1988
Two broad descriptors have been applied to the genesis of cardiac arrhythmias: abnormalities of impulse initiation and abnormalities of propagation. The first category include arrhythmias that are automatic, arising over a wide range of membrane potentials, and those that are triggered by early or delayed afterdepolarizations. Among conduction abnormalities, the ...
Easton D M - - 1988
1. The time course of force development by the heart is modelled by Gompertz kinetics from the product of two terms: a cumulative increase in relative number of activated "contractile units", and an exponential decrease in contractile force. 2. For each beat, an "initial condition" is specified by an "intrinsic ...
Hosaka T - - 1987
This article demonstrates one clinical application of biofeedback treatment with a microvibration (MV) transducer to relieve functional tremors. A MV transducer, a kind of accelerometer, was originally developed to detect invisible tremors from the body surface but this equipment is also utilized to detect visible tremors to convert them to ...
Hömberg V - - 1987
The effect of changes in mechanical limb properties on the peak frequency of different tremor forms was analysed. Wrist tremor was recorded by an accelerometer fixed to the dorsum of the hand and demodulated surface EMG was recorded from the wrist extensors, while the extended hand was loaded with successively ...
Calzetti S - - 1987
Amplitude/frequency characteristics of postural hand tremor in 59 patients with bilateral essential tremor of various degrees of severity were assessed using accelerometric recordings and spectral analysis. Intra-subject comparisons of tremor characteristics between the more and less affected hands were used to control for variability of tremor due to age factors ...
Uherík A - - 1987
The heart rate (HR) response to stimulation is described as a biphasic function with a phase of deceleration and acceleration. The deceleration is interpreted as a component of orienting behavior or of stimulus intake and acceleration as a sign of internal information processing going along with the rejection of external ...
Martin P - - 1987
We studied the dynamic interaction between the independent effects of sympathetic stimuli and heart period on atrial contractile force with three experiments: 1) we measured the inotropic response to brief sympathetic stimuli when the heart was paced; this represented the pure sympathetic effect on contractile force. 2) We measured the ...
Chen M H - - 1987
We report a new method for the noninvasive characterization of the frequency response of the autonomic nervous system (ANS) in mediating fluctuations in heart rate (HR). The approach entails computation of the transfer function magnitude and phase between instantaneous lung volume and HR. Broad band fluctuations in lung volume were ...
Rack P M PM Department of Physiology, Medical School, Birmingham, - - 1987
By coupling human limbs to a machine, which drives a single joint through sinusoidal flexion-extension movements, it is often possible to entrain the resting tremor of Parkinson's disease. Entrainment is most likely to occur when the imposed movement is large in amplitude and close in frequency to the spontaneous tremor.
Martin P - - 1986
We have characterized the dynamic interaction of the simultaneous changes of vagal activity and heart period on atrial contractile force. Our hypothesis was that the linear sum of these two separate effects was not equal to the response of the unpaced heart when both effects were elicited simultaneously. We performed ...
Opdam H J - - 1986
A new tremor-measuring device has been developed. It is constructed as a beam balance and measures principally in a vertical direction. Both arms of the beam contain a ceramic crystal; one of the arms has an extension that rests on the object to be measured. In this way, problems associated ...
Asso D - - 1986
The present study (N = 30) investigated the relationship between menstrual cycle changes in nervous system activity and in psychological, behavioural and physical variables. Two-flash fusion, electrodermal activity and questionnaire measures were used. Each participant was tested in the premenstrual phase (PM) and in the middle third of the cycle ...
Shinozaki H - - 1986
The effects of a newly synthesized compound, MLV-208, on drug-induced tremor were investigated in mice. The study involved a power spectral analysis of the random current induced by movement of a magnet attached to the mouse on a wire coil. To induce tremor, tremorine and harmaline were subcutaneously injected. The ...
Dykes F D - - 1986
The relationship between heart rate variability and respiration patterns was investigated using spectral analysis techniques in nine full-term infants whose ages ranged from 39-75 h. All the infants were studied during sleep, although no attempt was made to classify rapid eye movement or nonrapid eye movement states prospectively. The data ...
McFarland D H - - 1986
Jaw-closing force was transduced while subjects maintained a biting force of 9.8 N. To estimate the amplitude of tremor in each subject's force record, the average spectrum of the force was computed, and the definite integral of the averaged spectrum in the frequency range from 3.5 to 10 Hz was ...
Rack P M - - 1986
Forces and electromyograms were recorded from patients with Parkinson's disease during imposed joint movements. Muscles which were stretched by 3 to 5 Hz sinusoidally alternating movements often showed vigorous bursts of EMG activity whose timing established that it was a reflex response to the movement. The same movements provoke no ...
Slob A K - - 1986
Radiotelemetric recordings were made of uterine contractions in female stumptail macaques, and of heart and respiratory rate in stumptail monkeys of both sexes, before, during and after copulation. These data were fed into a multichannel recorder, along with a spoken record of behavioral changes. Males' heart and respiratory rates were ...
Ludwick-Rosenthal R - - 1985
There were two principal aims of the study: to carry out preliminary evaluation of a novel heartbeat tracking technique for objectively measuring cardiac interoception; and to determine whether good and poor heartbeat perceivers could be differentiated with respect to other parameters reflecting individual differences in emotionality, including gender and 'emotional ...
Shinozaki H - - 1985
The effects of diazepam, dantrolene and atropine on drug-induced tremors were investigated in mice from the point of view of the tremor frequency. The study involved a power spectral analysis of the random current induced by movement of a magnet (attached to the mouse) on a wire coil. To induce ...
Siegelová J - - 1985
The periodic oscillations of breathing pattern parameters were studied in 34 healthy subjects. In a three minutes' resting spirometric recording we determined the duration of inspiration, expiration and tidal volume in successive breaths and computed autocorrelation functions and power spectral density. Ten of the subjects were re-examined 2 years later. ...
Isokawa-Akesson M - - 1985
Fast Fourier Transform analyses were performed on finger tremor movements at 0.2-Hz intervals from 0.4 to 40 Hz in 10 human subjects, under a flickering light condition of 4-15 Hz and an unstimulated control condition. Under the control condition, the power spectrum showed an essentially normal curve distribution, except for ...
Rioux J N - - 1985
The frequency content of the ungated radionuclide time-activity curves for left and right ventricles was analyzed using a power spectrum estimation technique. This technique was applied to ten patients. It was observed that 75% of the contraction power of any ventricle was contained in the fundamental and at least 98% ...
Sigurd J - - 1985
The error arising when evaluating FHR variability on CTG curves is demonstrated. Visual estimation is based on the appreciation of oscillation amplitude (O.A.) which is necessarily dependent on basic heart frequency and the changes therein. It reflects variability in a distorted way--the distortion can be as great as 33% even ...
Pomeranz B - - 1985
Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and ...
Shinozaki H - - 1984
A method of analyzing tremor in mice was developed using a power spectral analysis of the random current induced by the movement of a magnet attached to a mouse, on a wire coil. The power spectral density function defined the frequency composition of the tremor, and the mean square value ...
Knott V J - - 1984
Previous research has demonstrated the presence of two heart rate acceleration responses to high intensity auditory stimuli. Both responses, the short latency acceleration peaking at 3-4 beats poststimulus and the long latency acceleration peaking at approximately 30-35 sec poststimulus, have been related to defensive responding to aversive stimuli and thus ...
Roels H - - 1983
The frequency spectrum of hand tremor amplitude was investigated in a group of 15 control subjects under four different conditions (rest position, wrist loading with 2 kg, pointer directed to a target, and wrist loading with 2 kg, pointer directed to a target, and wrist loading plus pointer). The series ...
Latimer W W Fachbereich Biologie, Philipps-Universität, D-3550 Marburg, Federal Republic of - - 1983
The responses of Tettigonia cantans to species-specific song and substrate conducted vibration have been tested under three experimental regimes. When directional cues are adequate the sound source can be located by audition alone; where such cues fail to provide sufficient information then vibration signals become of value. In two-choice experiments ...
Gottlieb S - - 1983
Continuous elevation of the middle finger for 15-60 min gave rise to modulation of the e.m.g. at 4-6 Hz. A marked peak (50-150% of the amplitude of the coexisting 8-12 Hz peak) at 4-6 Hz was produced in sixteen out of twenty-one subjects. The 8-12 Hz peak was also enhanced ...
Power R P - - 1983
A small light source viewed in the dark through an afterimage produced by an electronic flash may appear to move along short random paths. Experiment 1 shows that this is not an instance of the autokinetic phenomenon, and experiment 2 shows that it is not related to the 'fluttering hearts' ...
Goodman D - - 1983
The functional significance of physiological tremor - the high frequency (8-12 Hz), low amplitude oscillation that occurs during the maintenance of steady limb postures - is not known. Often tremor, perhaps because of its pathological manifestations, is considered a source of unwanted noise in the system, something to be damped ...
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