نتایج جستجو برای: low frequency oscillations

تعداد نتایج: 1620748  

Journal: :Optics express 2011
E S Andrianov A A Pukhov A V Dorofeenko A P Vinogradov A A Lisyansky

We demonstrate that when the frequency of the external field differs from the lasing frequency of an autonomous spaser, the spaser exhibits stochastic oscillations at low field intensity. The plasmon oscillations lock to the frequency of the external field only when the field amplitude exceeds a threshold value. We find a region of values of the external field amplitude and the frequency detuni...

2015
Sergey Abolmasov

In a recent paper [1], Boeuf has addressed the question of electron transport in low temperature E × B discharge devices using PIC MCC simulations. Using a general approach, it has been demonstrated that particle simulations can be an extremely powerful tool to unravel some of the mysteries of electron transport in these devices. Even through the aim of the paper was not to provide a complete r...

Journal: :Journal of applied physiology 2009
Jurgen A H R Claassen Benjamin D Levine Rong Zhang

Transfer function analysis of spontaneous oscillations in blood pressure (BP) and cerebral blood flow (CBF) can quantify the dynamic relationship between BP and CBF. However, such oscillation amplitudes are often small and of questionable clinical significance, vary substantially, and cannot be controlled. At the very low frequencies (<0.07 Hz), coherence between BP and CBF often is low (<0.50)...

2011
Andre M. Cravo Gustavo Rohenkohl Valentin Wyart Anna C. Nobre

34 Recent studies have associated increasing temporal expectations with synchronisation 35 of higher frequency oscillations and suppression of lower frequencies. In this experiment, we 36 explore a proposal that low-frequency oscillations provide a mechanism for regulating 37 temporal expectations. We used a speeded go/no-go task, and manipulated temporal 38 expectations by changing the probabi...

Journal: :Circulation 1998
J A Taylor D L Carr C W Myers D L Eckberg

BACKGROUND Survival of post-myocardial infarction patients is related inversely to their levels of very-low-frequency (0.003 to 0.03 Hz) RR-interval variability. The physiological basis for such oscillations is unclear. In our study, we used blocking drugs to evaluate potential contributions of sympathetic and vagal mechanisms and the renin-angiotensin-aldosterone system to very-low-frequency R...

Journal: :Brain Research 2016
Victor Chernomordik Franck Amyot Kimbra Kenney Eric Wassermann Ramon Diaz-Arrastia Amir Gandjbakhche

Functional Near Infrared Spectroscopy (fNIRS) can non-invasively capture dynamic cognitive activation and underlying physiological processes by measuring changes in oxy- and deoxy-hemoglobin levels, correlated to brain activation. It is a portable, inexpensive and user-friendly device which is easily adapted to the outpatient setting for the assessment of cognitive functions after Traumatic Bra...

Journal: :Arquivos de neuro-psiquiatria 2006
Carlos Julio Tierra-Criollo Antonio Fernando Catelli Infantosi

Oscillatory cerebral electric activity has been related to sensorial and perceptual-cognitive functions. The aim of this work is to investigate low frequency oscillations (<300 Hz), particularly within the gamma band (30-110 Hz), during tibial stimulation. Twenty-one volunteers were subjected to 5 Hz stimulation by current pulses of 0.2 ms duration and the minimum intensity to provoke involunta...

2012
J. Usman M. W. Mustafa J. J. Jamian G. Aliyu

The major concern in power systems has been the problem of low frequency oscillations (LFO) that results in the reduction of the power transfer capabilities. The applications of power system stabilizers (PSS) are commonly employed to dampen these low frequency oscillations. The parameters of the PSS are tuned by considering the Heffron-Phillips model of a single machine infinite bus system (SMI...

Journal: :Physiological measurement 2007
A B Rowley S J Payne I Tachtsidis M J Ebden J P Whiteley D J Gavaghan L Tarassenko M Smith C E Elwell D T Delpy

Wavelet cross-correlation (WCC) is used to analyse the relationship between low-frequency oscillations in near-infrared spectroscopy (NIRS) measured cerebral oxyhaemoglobin (O(2)Hb) and mean arterial blood pressure (MAP) in patients suffering from autonomic failure and age-matched controls. Statistically significant differences are found in the wavelet scale of maximum cross-correlation upon po...

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