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Results 251 - 300 of 643
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Legros Alexandre - - 2005
Extremely low frequency (ELF) magnetic fields (MF) are omnipresent in our modern daily environment, but their effects on humans are still not clearly established. The aim of this study was to determine the effect of a 50 Hz, 1,000 microT MF centered at the level of the head on human ...
Sait Mardi L - - 2006
The question of whether power-frequency magnetic fields of strengths relevant to industrial exposure can affect heart rhythm remains controversial. Because the reported effects on heart rate (HR) are so small, procedures which can provoke changes in the sympathovagal balance in a controlled manner may have a greater capacity for identifying ...
Pellegrini B - - 2005
AIM: Air pistol shooting is a sport requiring extreme movement precision. The purpose of our study is to collect and analyze kinematic data of arm/gun complex during the pointing phase in order to characterize movement and between segment coordination by means of time and frequency domain analysis techniques. METHODS: Thirteen ...
Sztajzel Juan - - 2006
This study examined spectral components of heart rate variability (HRV) during endurance mountain running in 8 healthy trained subjects. The data showed that during this type of mountain running, all spectral components of HRV may severely decrease, particularly very-low-frequency and low-frequency (LF) power, suggesting extreme activation of the sympathetic nervous ...
Cathers Ian I School of Biomedical Sciences, Faculty of Health Sciences, The University of Sydney, PO Box 170, 1825, Lidcombe, NSW, Australia. - - 2006
In this study the systematic modulation of wrist flexor muscle activity by imposed joint movement was examined. Ten subjects maintained a constant contraction level (25% of the maximum; trial duration: 20 s) in flexor carpi radialis while their wrists were perturbed with 50 different quasi-sinusoidal signals (frequency range: 0.5-9.5 Hz; ...
McDougall Stuart J - - 2005
During stress the sympathoadrenal system and the hypothalamo-pituitary-adrenal axis act in a coordinated manner to force changes within an animal's current physiological and behavioral state. Such changes have been described as 'fight flight' or stress responses. The central nervous system may generate a stress response by different neural circuits, this ...
Farkas Zsuzsanna - - 2006
We investigated the asymmetry of tremor intensity, frequency and frequency dispersion of Parkinsonian (PT) and essential (ET) tremor using accelerometry. Data of the more and less trembling hands were statistically elaborated. We found that tremor intensity was significantly asymmetric not only in PT but also in ET, while frequency and ...
Verheyden Bart - - 2005
Parabolic flight is used to create short successive periods of changing gravity in a range between 0 and 1.8 Gz (1 Gz: 9.81 m/s(2)). The purpose of the present study was to evaluate whether cyclic variations in heart rate during +/-20 s periods of stable gravity in parabolic flight reflect ...
Sowman Paul F - - 2005
This paper discusses, using the human jaw as a model, some of the commonly used techniques for examining physiological tremor. The EMG component driving mandibular physiological tremor approximately 7Hz can be revealed in the time domain manifestation of EMG by demodulation. The co-occurrence of approximately 7Hz physiological tremor (PT) in ...
Christakos Constantinos N - - 2006
We present results from a study of the 6-to 12-Hz force tremor in relation to motor unit (MU) firing synchrony. Our experimental observations from 32 subjects, 321 contractions, and 427 recorded MUs reveal that tremor is accompanied by corresponding, in-phase MU rhythms that are additional to the ones at the ...
Meehan Michael - - 2005
A common measure of effectiveness of a virtual environment (VE) is the amount of presence it evokes in users. Presence is commonly defined as the sense of being there in a VE. There has been much debate about the best way to measure presence, and presence researchers need and have ...
Mitani Satoko - - 2006
OBJECT: The purpose of this study was to compare the stress levels of Japanese ambulance men between on-duty and off-duty days, by using the physiological indices of heart rate variability (HRV) and cortisol in urine, measured over each 24-h period. METHODS: Measurements were made during one on-duty and one off-duty ...
Holmqvist Fredrik - - 2005
Heart rate during sinus rhythm is modulated through the autonomic nervous system, which generates short-term oscillations. The high-frequency components in these oscillations are associated with respiration, causing sinus arrhythmia, mediated by the parasympathetic nervous system. In this study, we evaluated whether slow, controlled respiration causes cyclic fluctuations in the frequency ...
Raethjen J - - 2005
It has been postulated that Parkinsonian action tremor is distinct from classical resting tremor and that it may contribute to a loss of manual dexterity in Parkinson's disease. We analyzed pinch grip coordination in 20 patients with Parkinson's disease. An object with and without an additional 500 g weight was ...
Aysin Benhur - - 2005
Although a number of time-frequency representations have been proposed for the estimation of time-dependent spectra, the time-frequency analysis of multicomponent physiological signals, such as beat-to-beat variations of cardiac rhythm or heart rate variability (HRV), is difficult. We thus propose a simple method for 1) detecting both abrupt and slow changes ...
Duval Christian - - 2005
OBJECTIVE: The present study assessed the impact of ventrolateral (VL) thalamotomy on the high-frequency components of tremor in patients with Parkinson's disease (PD). METHODS: Tremor was recorded prior to, and 7 days post-surgery using a laser displacement sensor. In addition, tremor was recorded in 10 age-matched patients with PD showing ...
Takanokura Masato - - 2005
BACKGROUND: Physiological tremor is an involuntary and continuous oscillation in every limb segment of a healthy human. This study investigates the neuromuscular control of physiological tremor by an elastic load applied to the middle finger. MATERIAL/METHODS: The subject maintained a stretching position of the middle finger against various tension springs. ...
Duval Christian C Faculty of Applied Health Science, Brock University, 500 Glenridge Ave, St. Catharines, Ontario, Canada. - - 2005
The goal of this study was accurate quantification of the amplitude of high-frequency components of physiological tremor (PT) in units of displacement, velocity, and acceleration. In addition, changes of amplitude with finger loading were compared within specific frequency bands. Index finger tremor was measured for 20 healthy subjects using a ...
van Steenis H G - - 2005
The statistical properties of the time- and frequency-domain characteristics of heart rate variability are known to vary over time. A method is presented to compute the time-varying spectral contents of the characteristic narrow-band frequency components of heart rate variability by means of the instantaneous amplitude and frequency at an optimal ...
Wang Shou-Yan - - 2005
In order to investigate the dynamic change in transient neuromuscular events and the functional correlation between the neural and muscular activity, local field potentials (LFPs) of the subthalamic nucleus (STN) and surface electromyograms (sEMGs) over several episodes of transient resting tremor from a patient with Parkinson's disease were quantitatively characterised ...
Cuvillon Loïc - - 2005
Active robotic filtering is a promising solution for beating heart Totally Endoscopic Coronary Artery Bypass Grafting (TECABG). n this work, we assess the heart motion dynamics using simultaneously igh speed imaging of optical markers attached to the heart, ECG signals and ventilator airflow acquisitions. Our goal is to make an ...
Choi David D The Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213, - - 2005
This paper presents the design and initial experimental results of a flexure-based parallel manipulator that is actuated by three piezoelectric stacks. The manipulator is for an active handheld tremor canceling device for microsurgery. By using flexures to approximate pin and ball joints, errors due to friction, backlash, and imperfect assemblies ...
Li Z Y ZY College of Bio-information, Chongqing University of Post and Telecommunication, Chongqing 400065 China. E-mail: - - 2005
Independent component analysis (ICA) and neural networks were used to extract sub-signals of heart rate variability (HRV). Electrocardiogram (ECG) recording was consisted of six minutes when the volunteer was lying and another six minutes when the volunteer was standing. HRV was extracted from ECG. According to time-delay, HRV was divided ...
Kim Sunghan S Biomedical Signal Processing Laboratory, Electrical & Computer Engineering, Portland State University, Portland, Oregon, USA. Email: - - 2005
Tremor is one of the most disabling symptoms in patients with many movement disorders including Parkinson's disease (PD) and essential tremor (ET). Neural tremor, which is measured by microelectrodes placed near nerve cells or obtained from brain cells during stereotactic neurosurgery, is due to the fluctuation of the firing rate ...
Lee Chung C Yonsei University, Seoul, Korea (phone: 822-222-81922; fax: 822-361-9923; e-mail: - - 2005
The purpose of this paper is to estimate emotions using Neural network and the changes in activities of autonomic nervous system(ANS). Since ANS cannot be controlled artificially, we presumed that the changes in emotions would be reflected to the changes in ANS. In order to observe those changes, we provided ...
Bernadic M - - 2005
Fractionated heart activation can be detected as late potentials from surface recordings of signal-averaged electrocardiograms (SA ECG) which are considered as a marker of sustained ventricular tachycardia. For animal studies, reference values in time and frequency domain analyses are essentially missing. In the present study, we have established reference values ...
Princi Tanja - - 2005
Evaluation of heart rate variability (HRV) is based on analysis of consecutive R-R intervals and may provide quantitative information on the modulation of cardiac vagal and sympathetic efferent activities. In particular, power spectral analysis as well as the fractal dimension of HRV represent non-invasive measures that reflect brain-heart interaction in ...
Choi David D The Robotics Institute, Carnegie Mellon University, Pittsburgh, PA 15213, - - 2005
This paper presents the design and initial experimental results of a flexure-based parallel manipulator that is actuated by three piezoelectric stacks. The manipulator is for an active handheld tremor canceling device for microsurgery. By using flexures to approximate pin and ball joints, errors due to friction, backlash, and imperfect assemblies ...
Allan L M - - 2005
Heart rate variability (HRV) is a sensitive method for the assessment of autonomic function and requires little cooperation from the subject, making it suitable for use in dementia. Preliminary studies have suggested that HRV may be impaired in Alzheimer's disease (AD). HRV has not been studied in vascular dementia (VAD). ...
Stiles Martin K - - 2004
BACKGROUND: Wavelet-based methods of analyzing ECG signals have been used to identify specific features in cardiac arrhythmias. Since some of these features are rate dependent, it is a requirement that they are examined across a range of physiological heart rates. The wavelet transform is a signal analysis tool that can ...
Lee J J - - 2004
The Moving Actuator type artificial heart(AnyHeart) as well as many other artificial hearts uses a motor as its power source. For controllability of control parameters such as pump rate, pump output, blood pressure profile and flow form, the precise motor speed control is important. However, because the implantable device has ...
Raethjen J - - 2004
OBJECTIVE: Quantitative tremor analyses using almost identical methods were compared between two independent large normal cohorts, to separate robust measures that may readily be used diagnostically from more critical ones needing lab-specific normalization. METHODS: Hand accelerometry and surface EMG from forearm flexors and extensors were recorded with (500 and 1000 ...
Fadel Paul J - - 2004
The present study was designed to characterize respiratory fluctuations in awake, healthy adult humans under resting conditions. For this purpose, we recorded respiratory movements with a strain-gauge pneumograph in 20 subjects. We then used Allan factor, Fano factor, and dispersional analysis to test whether the fluctuations in the number of ...
Nomura M - - 2004
BACKGROUND: Nitrates decrease the tone of the lower oesophageal sphincter, and may thus induce gastro-oesophageal reflux. AIM: In the present study, we evaluated electrogastrographic changes and heart-rate variability before and after the administration of nitrates. METHODS: In 15 patients with chest pain treated with nitrates, electrocardiography and percutaneous electrogastrography were ...
Strath Scott J - - 2004
PURPOSE: Two methods of measuring physical activity (PA) were compared over a consecutive 7-day period among 25 adults (12 men and 13 women). METHODS: Each day estimates of energy expended in light, moderate, vigorous, and total PA were derived from the simultaneous heart-rate motion sensor (HR+M) technique. At the end ...
Tanaka Kunihiko - - 2004
INTRODUCTION: Wavelet transform is used for time-frequency analysis. Recently, discrete wavelet transform (DWT) has been used to analyze R-R interval or heart rate variability. However, we hypothesized that wavelet packet transform (WPT) is a better way to analyze such variability. In the present study, we compared resolution of frequency band ...
Gao J B - - 2004
Variations in the amplitude and period of essential and Parkinsonian tremors were studied. It was found that the variations in frequency (or period) were mostly similar to the white noise, with the standard deviation typically less than 10% of the mean, whereas the variations in amplitude were much larger, with ...
Hirayanagi Kaname - - 2004
We studied the effects of 14 days of 6 degrees head-down bed rest (HDBR) in 16 healthy male subjects to examine the functional changes in the autonomic nervous system and cardiac baroreceptor reflex response with an emphasis on dynamic changes during HDBR. Beat-by-beat RR intervals (RRIs) and systolic arterial pressures ...
Aubert André E - - 2004
Our immediate goal was to study heart rate variability (HRV) in chicken embryos in the egg. Instantaneous heart rate data were needed for this purpose, and accordingly an ECG recording method in the egg was developed. The aim of this work was to test the hypothesis that autonomic nervous cardiac ...
Co┼čkun Banu - - 2004
Cypermethrin is widely used as an insecticide on animals and in agriculture, the home, and the garden. The effect of inhaled cypermethrin on the cardiac mechanics, electrophysiology, and ultrastructure in frogs was investigated in this study. Four groups received 100 microL of cypermethrin via inhalation for different exposure times, and ...
Grossman P - - 2004
Ambulatory respiratory sinus arrhythmia (RSA) or high-frequency heart rate (HR) variability is frequently employed as an index of cardiac parasympathetic control and related to risk or severity of cardiovascular disease. However, laboratory studies indicate variations in physical activity and respiratory parameters of rate and tidal volume may confound estimation of ...
Scotten Lawrence N - - 2004
BACKGROUND AND AIM OF THE STUDY: Fluid dynamic forces, valve design factors and gravity interactively determine the complex motion of prosthetic heart valve occluders. Although motion has been investigated, in vitro, using high-speed image recording, the technique has significant cost and limitations on resolution. METHODS: The kinematics of mechanical and ...
Kupka T T Dept. of Biomedical Informatics, Institute of Medical Technol. & Equipment, Zabrze, - - 2004
Among various methods of monitoring fetal heart activity a Doppler ultrasound technique is the most often used. Complexity and variability of Doppler signal make difficult the precise measurement of timing dependences defining individual phases of cardiac cycle. Aim of the work was to carry out detailed comparative analysis of Doppler ...
Thong Tran T Dept. of Biomedical Eng., Oregon Health & Sci. Univ., Beaverton, OR, - - 2004
Heart rate variability (HRV) is frequently used to measure autonomic nervous system (ANS) activity. However, little is known about the mechanism underlying pharmacologically induced changes in HRV. Previous research has shown that nicotine exposure stimulates the ANS, mediating a wide spectrum of physiological and behavioral effects, including altered respiratory sinus ...
Padhye N S NS The University of Texas Health Science Center, Houston, Texas, - - 2004
Fetal heart rate variability (fHRV) is useful for noninvasive assessment of the status of the autonomic nervous system of the developing fetus. In this pilot study we acquired fetal magnetocardiograms (fMCG) in a magnetically shielded environment. Each recording was of 5-minute duration and was subsequently repeated in a high-frequency noise ...
Vehkaoja A A Institute of Measurement & Information Technology, Tampere University of Technology, Tampere, - - 2004
A light wearable wireless biopotential measurement device built up of commercial components is presented. The device utilizes 868 MHz ISM license free frequency band. Very low noise and good interference rejection is achieved using three electrode differential amplifier design and wireless signal transfer. The device has a possibility of calculating ...
Fadel Paul J - - 2004
Muscle sympathetic nerve activity (MSNA) in resting humans is characterized by cardiac-related bursts of variable amplitude that occur sporadically or in clusters. The present study was designed to characterize the fluctuations in the number of MSNA bursts, interburst interval, and burst amplitude recorded from the peroneal nerve of 15 awake, ...
Carrasco S - - 2003
PRIMARY OBJECTIVE: Due to limited and contradictory information available, the reproducibility of temporal and spectral measurements of heart rate variability from short-term recordings was evaluated in normal subjects during supine, controlled breathing, standing, exercise and recovery conditions. METHODS AND PROCEDURES: Five-minute tachograms from 11 individuals were obtained during the specified ...
Beuter Anne - - 2003
Rest tremor was quantified in the index finger tip of 16 patients with Parkinson's disease (PD) receiving deep brain stimulation (DBS) of the ventro-intermediate nucleus (Vim) of the thalamus, the subthalamic nucleus (STN), or the internal part of the globus pallidus (GPi) while being off L-dopa for 12h. Clinically, without ...
Kuusela Tom A - - 2003
The aim of this study was to explore the principal frequency components of the heart rate and blood pressure variability in the low frequency (LF) and very low frequency (VLF) band. The spectral composition of the R-R interval (RRI) and systolic arterial blood pressure (SAP) in the frequency range below ...
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