Search results for "amplitud"
showing 10 items of 1171 documents
Increased amplitudes of distortion product otoacoustic emissions in patients with unilateral acoustic neuroma.
2004
We present a case series of 4 patients with a unilateral acoustic neuroma and increased amplitudes of the distortion products of otoacoustic emissions (DPOAEs) at the low- and middle- frequency bandwidth on the involved side compared to the uninvolved side despite a 28-dB hearing level (HL) worse (compared to the uninvolved side) pure-tone hearing threshold average for standard audiometric frequencies between 1 and 6 kHz at the involved side. In 3 of these patients, 2 with an inferior vestibular nerve origin of the acoustic neuroma and one in whom the nerve of origin could not be unequivocally defined, the tumor was extending extrameatally. One patient had a purely intrameatal acoustic neur…
Motor unit activation patterns during isometric, concentric and eccentric actions at different force levels.
2002
Motor unit activation patterns were studied during four different force levels of concentric and eccentric actions. Eight male subjects performed concentric and eccentric forearm flexions with the movement range from 100 degrees to 60 degrees in concentric and from 100 degrees to 140 degrees elbow angle in eccentric actions. The movements were started either from zero preactivation or with isometric preactivation of the force levels of 20, 40, 60 and 80% MVC. The subjects were then instructed to maintain the corresponding relative force levels during the dynamic actions. Intramuscular and surface EMG was recorded from biceps brachii muscle. Altogether 28 motoneuron pools were analyzed using…
Neuromuscular fatigue during dynamic maximal strength and hypertrophic resistance loadings
2011
The purpose of this study was to compare the acute neuromuscular fatigue during dynamic maximal strength and hypertrophic loadings, known to cause different adaptations underlying strength gain during training. Thirteen healthy, untrained males performed two leg press loadings, one week apart, consisting of 15 sets of 1 repetition maximum (MAX) and 5 sets of 10 repetition maximums (HYP). Concentric load and muscle activity, electromyography (EMG) amplitude and median frequency, was assessed throughout each set. Additionally, maximal bilateral isometric force and muscle activity was assessed pre-, mid-, and up to 30 min post-loading. Concentric load during MAX was decreased after set 10 (P<0…
Comparison of the sympathetic skin response and continuous wave Doppler sonography of the radial artery.
1999
The value of neurophysiological tests of the autonomic nerve system is limited. One of the clinically most commonly applied test is the skin sudomotor response, frequently referred to as 'sympathetic skin response' (SSR). However, the SSR is a more qualitative than quantitative evaluation technique. Continuous wave (cw) Doppler sonography of the radial artery may be an alternative quantitative approach. We studied 41 age matched volunteers (23 female, 18 male; 16-82 years (mean age 53 years)). The stimulus was a loud and unexpected acoustic signal, alternatively a cough. SSR evaluation included the latency of onset, the duration and the amplitude of the response. Doppler evaluation also inc…
Covariation of spectral and nonlinear EEG measures with alpha biofeedback.
2002
Item does not contain fulltext This study investigated how different spectral and nonlinear EEG measures covaried with alpha power during auditory alpha biofeedback training, performed by 13 healthy subjects. We found a significant positive correlation of alpha power with the largest Lyapunov-exponent, pointing to an increased dynamical instability of the EEG accompanying alpha enhancement. Alpha power amplification, moreover, was significantly correlated with a decrease of spectral entropy within the alpha range. This outcome reflects a sharpening of the alpha peak during biofeedback training. The fact that the sharpening effect clearly preceded the increase of alpha amplitude could be exp…
Relationship between electrical and mechanical properties of motor units.
1990
In six healthy volunteers, the size of the motor unit action potential (MUAP) was related to its contractile behaviour. Electrical activity was determined by measuring amplitude and area of the potential, using the macro electromyography (EMG) technique. The mechanical response was characterised by contraction time, twitch force and relaxation time, recorded with the spike triggered averaging technique. With increasing tension of the whole muscle corresponding to an increasing threshold, the force of single units enlarged exponentially compared to their EMG. There was only a weak relationship between contraction time and electrical activity and none between EMG and relaxation time.
Avaliação da resposta de acomodação após tarefas visuais próximas usando diferentes dispositivos eletrônicos portáteis
2015
ABSTRACT Purpose: To assess the accommodation response after short reading periods using a tablet and a smartphone as well as determine potential differences in the accommodation response at various stimulus vergences using a Hartmann- Shack aberrometer. Methods: Eighteen healthy subjects with astigmatism of less than 1 D, corrected visual acuity of 20/20 or better, and normal findings in an ophthalmic examination were enrolled. Accommodation responses were obtained under three different conditions: accommodation system of the eye relaxed and visually stressed with a tablet and an smartphone for 10 min, at a distance of 0.25 m from the subject's eyes. Three measurements of accommodation res…
Latency and amplitude variability in serial median nerve SEP recordings
1999
Abstract Objectives : Intra-individual variability of SEP parameters was investigated by serial SEP recordings. Methods : Median nerve SEP of 53 normal subjects (mean age 25.5±2.7 years) were evaluated. Recordings were repeated 1 week, 2 weeks, and 6 months after the initial recording. Results : Mean values of latencies from right median nerve stimulation were slightly longer (+0.1 ms) as compared to the left. The intra-individual (within stimulation side) variance did not depend on the time interval between recordings. The total within-stimulation-side variance of latencies was 0.056 ms 2 for N20 (C 3/4 ′ vs. F z ), 0.070 ms 2 for N13 (C 7 vs. F z ), 0.048 ms 2 for N10 (Erb's point vs. F z…
Effects of contralateral white noise stimulation on transitory evoked otoacoustic emissions in patients with acoustic neuroma.
1995
Abstract Transitory evoked otoacoustic emissions are normal phenomena observed in most persons with hearing levels greater than 35 dB. Further, masking of the contralateral ear produces amplitude reductions in the transitory evoked otoacoustic emissions. We have undertaken a study of transitory evoked otoacoustic emissions in 20 patients with acoustic neuroma. All patients were assessed for transitory evoked otoacoustic emissions bilaterally, with and without contralateral masking with white band noise at 40, 50, and 60 dB. We found that transitory evoked otoacoustic emissions were present in 30% of ears with tumor and that the presence of transitory evoked otoacoustic emissions is associat…
<title>Fibers supporting super-Gaussian beams: cladding effects</title>
1996
We define a matching function that describes the amplitude variations produced over supergaussian beams, by cladding optical fibers that, if uncladded, can sustain this type of beams as Eigenmodes.