Contributors: Eugene Grichuk, Margarita Kuzmina, Eduard Manykin

Date: 2010-09-26

qubit simulates the behavior of electric field of polarized light beam...qubit model has been designed as a stochastic oscillator formed by a pair...qubits that is exploited as a computation resource in one-way quantum ...qubit cluster, is designed, and system of equations for network dynamics...one-qubit gates are suggested. Changing of cluster entanglement degree...oscillators is proposed for modeling of a cluster of entangled qubits ...oscillators with chaotically modulated limit cycle radii and frequencies...oscillators...qubit model has been designed as a stochastic oscillator formed by a pair ... A network of coupled stochastic oscillators is proposed for modeling of a cluster of entangled qubits that is exploited as a computation resource in one-way quantum computation schemes. A qubit model has been designed as a stochastic oscillator formed by a pair of coupled limit cycle oscillators with chaotically modulated limit cycle radii and frequencies. The qubit simulates the behavior of electric field of polarized light beam and adequately imitates the states of two-level quantum system. A cluster of entangled qubits can be associated with a beam of polarized light, light polarization degree being directly related to cluster entanglement degree. Oscillatory network, imitating qubit cluster, is designed, and system of equations for network dynamics has been written. The constructions of one-qubit gates are suggested. Changing of cluster entanglement degree caused by measurements can be exactly calculated.

Contributors: unknown

Date: 2015-01-01

High-frequency oscillations...frequency ictal patterns, ictal high-frequency oscillations, hyperexcitability...High-frequency oscillations (HFOs, 80–500Hz) from intracranial electroencephalography...frequency oscillations, CFIP=conventional frequency ictal patterns. ... High-frequency oscillations (HFOs, 80–500Hz) from intracranial electroencephalography (EEG) may represent a biomarker of epileptogenicity for epilepsy. We explored the relationship between ictal HFOs and hyperexcitability with a view to improving surgical outcome.

Contributors: unknown

Date: 2010-09-13

frequency spectra of a coupling oscillation and the associated phase-coupled...high-frequency bursts that are coupled to a common low-frequency oscillation...frequency spectra produced by the tensor decomposition. All identified...oscillation. This mechanism requires multiple physiologically different...frequency spectrum. We showed that, with this source definition, the array...frequency spectra (both real-valued), which is exactly the structure that...high-frequency oscillations that are phase-coupled to a low-frequency ...high-frequency oscillations. Using human intracranial EEG (iEEG) data,...oscillation. In panel d, with green and index f, we show the frequency...low-frequency coupling oscillation and the others generating phase-coupled...frequencies of the coupling oscillations (vertical axis). The central ...frequency spectrum) and in terms of the neuronal network that generates...frequency spectra, then they can be extracted by means of tensor decomposition...oscillations are much more widespread than the ones for the associated...frequency of the coupling oscillation), respectively, y-axes (showing ... Spatially distributed coherent oscillations provide temporal windows of excitability that allow for interactions between distinct neuronal groups. It has been hypothesized that this mechanism for neuronal communication is realized by bursts of high-frequency oscillations that are phase-coupled to a low-frequency spatially distributed coupling oscillation. This mechanism requires multiple physiologically different interacting sources, one generating the low-frequency coupling oscillation and the others generating phase-coupled high-frequency oscillations. Using human intracranial EEG (iEEG) data, we provide evidence for multiple oscillatory patterns, as characterized on the basis of their spatial maps (topographies) and their frequency spectra. In fact, we show that the spatial maps for the coupling oscillations are much more widespread than the ones for the associated phase-coupled bursts. Second, in the majority of the patterns of phase-amplitude coupling (PAC), phase-coupled bursts of high-frequency activity are synchronized across brain areas. Third and last, working memory operations affect the PAC strength in a heterogeneous way: in some PAC patterns, working memory operations increase their strength, whereas in others they decrease it.

Contributors: unknown

Date: 2016-01-08

Frequency main effects on ALFF. Hot colors represent increased ALFF in...frequency (slow-4 and slow-5) interaction effects on ALFF. The regions...low-frequency oscillation (LFO) of major depressive disorder (MDD) patients...frequency dependent....Low-frequency oscillation...Frequency dependence...frequency interaction effects on ALFF (hot colors): the left ventromedial...frequency on ALFF. (a) The group main effects on ALFF. Hot colors represent...frequency (slow-4 and slow-5) interaction effects on ALFF. ... We conducted this fMRI study to examine whether the alterations in amplitudes of low-frequency oscillation (LFO) of major depressive disorder (MDD) patients were frequency dependent.

Contributors: unknown

Date: 2009-10-06

Oscillation Frequency...Frequency in Moth AL Model...Oscillation Coherence, Not Frequency...oscillation frequency. However, changing the concentration of the odor...Oscillations in the Moth MB and AL...Oscillations in Model of Moth AL...oscillations suddenly slowed as net olfactory receptor neuron (ORN) output...oscillations? In the olfactory system of the moth, we found that odors...frequency. Our recordings in vivo and computational models based on these...oscillation frequency is set by the adaptation and saturation of this ... In many species, sensory stimuli elicit the oscillatory synchronization of groups of neurons. What determines the properties of these oscillations? In the olfactory system of the moth, we found that odors elicited oscillatory synchronization through a neural mechanism like that described in locust and Drosophila. During responses to long odor pulses, oscillations suddenly slowed as net olfactory receptor neuron (ORN) output decreased; thus, stimulus intensity appeared to determine oscillation frequency. However, changing the concentration of the odor had little effect upon oscillatory frequency. Our recordings in vivo and computational models based on these results suggested that the main effect of increasing odor concentration was to recruit additional, less well-tuned ORNs whose firing rates were tightly constrained by adaptation and saturation. Thus, in the periphery, concentration is encoded mainly by the size of the responsive ORN population, and oscillation frequency is set by the adaptation and saturation of this response.

Contributors: unknown

Date: 2013-10-29

frequency oscillations at which pHFO amplitudes were maximal was inconsistent...oscillations (p<0.01). These results suggest that increased CFC between...frequency oscillations (pHFOs) have been proposed to be robust markers...oscillations, whereas pathological ripple amplitudes preferentially occurred...frequency amplitude by low-frequency phase. In the seizure-onset zone,...oscillations is observed. There is also less cross-frequency coupling ...frequency range has been shown to be modulated by phase of lower frequency...oscillations during the ictal period. In the interictal period, no specific...frequency oscillations...Cross-frequency coupling...frequency phase, we measured the preferred slow oscillatory phase at which...frequencies (x-axis) by the phases of other narrow-band frequencies (y-axis...oscillations (p=0.14 and p=0.68, respectively). At seizure termination...frequency oscillations, sorted by concurrent low-frequency phase into ...oscillations. Here, we tested the hypothesis that dynamic cross-frequency ... Pathological high frequency oscillations (pHFOs) have been proposed to be robust markers of epileptic cortex. Oscillatory activity below this frequency range has been shown to be modulated by phase of lower frequency oscillations. Here, we tested the hypothesis that dynamic cross-frequency interactions involving pHFOs are concentrated within the epileptogenic cortex. Intracranial electroencephalographic recordings from 17 children with medically-intractable epilepsy secondary to focal cortical dysplasia were obtained. A time-resolved analysis was performed to determine topographic concentrations and dynamic changes in cross-frequency amplitude-to-phase coupling (CFC). CFC between pHFOs and the phase of theta and alpha rhythms was found to be significantly elevated in the seizure-onset zone compared to non-epileptic regions (p<0.01). Data simulations showed that elevated CFC could not be attributed to the presence of sharp transients or other signal properties. The phase of low frequency oscillations at which pHFO amplitudes were maximal was inconsistent at seizure initiation, yet consistently at the trough of the low frequency rhythm at seizure termination. Amplitudes of pHFOs were most significantly modulated by the phase of alpha-band oscillations (p<0.01). These results suggest that increased CFC between pHFO amplitude and alpha phase may constitute a marker of epileptogenic brain areas and may be relevant for understanding seizure dynamics.

Contributors: unknown

Date: 2013-08-15

oscillation dynamics of a sessile drop, such as resonance frequency and...frequencies (frequency range of 20–110Hz in which the first and second...frequency, but strongly affects the oscillation amplitude and peak width...oscillation....oscillation amplitude, in response to different AC voltages (80 and 100Vrms...frequency...Frequency response at harmonic and subharmonic frequencies....frequency....oscillating drops with different viscosities along with AC frequency at...oscillating drops with different viscosities for different frequencies...frequency. In addition, drop oscillation in the resonance mode is no longer...oscillation ... The effects of drop viscosity on oscillation dynamics of a sessile drop, such as resonance frequency and oscillation amplitude, in response to different AC voltages (80 and 100Vrms, corresponding to the electrowetting number η of 0.25 and 0.39, respectively) and frequencies (frequency range of 20–110Hz in which the first and second resonance frequencies exist) were investigated, based on both experiments and theoretical modeling. The results show that drop viscosity rarely affects resonance frequency, but strongly affects the oscillation amplitude and peak width of the resonance frequency. In addition, drop oscillation in the resonance mode is no longer observed, when the drop viscosity is over the critical value, which increases with applied AC voltage. A theoretical model predicts the oscillation dynamics of sessile drops within the error level of ±5%, except for the drop with high viscosity (60mPas). Moreover, the friction coefficient obtained by fitting the theoretical models is nearly proportional to the drop viscosity. Finally, an empirical relationship, in which the maximum amplitude is inversely proportional to the drop viscosity, is obtained.

Contributors: unknown

Date: 2009-04-28

frequencies. The amplitude and frequency of these oscillations are continuously...Oscillation Cycle...Oscillation Cycles...Oscillations In Vivo...Frequency in Simple Model of CA3 Circuit...oscillation frequency. So, by rapidly balancing excitation with inhibition...oscillation predicts the interval to the next. Using in vivo and in vitro...Oscillation Amplitude Predicts Latency to Next Oscillation Cycle...oscillation amplitude and frequency vary rapidly, from one cycle to the...oscillations over a wide band of frequencies. ... Neurons recruited for local computations exhibit rhythmic activity at gamma frequencies. The amplitude and frequency of these oscillations are continuously modulated depending on stimulus and behavioral state. This modulation is believed to crucially control information flow across cortical areas. Here we report that in the rat hippocampus gamma oscillation amplitude and frequency vary rapidly, from one cycle to the next. Strikingly, the amplitude of one oscillation predicts the interval to the next. Using in vivo and in vitro whole-cell recordings, we identify the underlying mechanism. We show that cycle-by-cycle fluctuations in amplitude reflect changes in synaptic excitation spanning over an order of magnitude. Despite these rapid variations, synaptic excitation is immediately and proportionally counterbalanced by inhibition. These rapid adjustments in inhibition instantaneously modulate oscillation frequency. So, by rapidly balancing excitation with inhibition, the hippocampal network is able to swiftly modulate gamma oscillations over a wide band of frequencies.

Contributors: unknown

frequency throughout the SO cycle....frequency. (C) Phase response curve of a type I neuronal oscillator: any...frequencies, with maximal FO power for these two frequencies in antiphase...frequency modulation within a single FO frequency band, as shown in (A...cross-frequency coupling, including neural representations of multiple...cross-frequency coupling (CFC) network with sparse-spiking FO oscillations...oscillations...oscillations are ubiquitously observed in the mammalian brain, but it ...cross-frequency coupling. We show that different types of neural oscillators...oscillation (FO). Plot shows FO amplitude as a function of slow oscillation...frequencies (pointing to distinct oscillation-generation mechanisms) should...cross-frequency interactions yield distinct signatures in neural dynamics...cross-frequency coupling...oscillators. Neural oscillations in distinct frequency bands are generated...frequency of type I and type II neurons as a function of driving-current...oscillations at different timescales has recently received much attention...Cross-Frequency Neural Coupling. (A–D) Cross-frequency coupling (CFC) ... Neural oscillations are ubiquitously observed in the mammalian brain, but it has proven difficult to tie oscillatory patterns to specific cognitive operations. Notably, the coupling between neural oscillations at different timescales has recently received much attention, both from experimentalists and theoreticians. We review the mechanisms underlying various forms of this cross-frequency coupling. We show that different types of neural oscillators and cross-frequency interactions yield distinct signatures in neural dynamics. Finally, we associate these mechanisms with several putative functions of cross-frequency coupling, including neural representations of multiple environmental items, communication over distant areas, internal clocking of neural processes, and modulation of neural processing based on temporal predictions.

Contributors: Abdul-Niby, M., Alameen, M., Baitie, H.

Date: 2016-12-18

frequency synthesis, quadrature signal generation and phase locked loops...oscillator (ILO) of 35MHz frequency. Phase shifters at high frequencies...oscillator...Oscillating systems, locking of the oscillators can take place for injected...frequency to nth harmonics of the free-running frequency. In this paper ... In Self Oscillating systems, locking of the oscillators can take place for injected signals close in frequency to nth harmonics of the free-running frequency. In this paper, we present a simple design for digital phase shift control by using a harmonically injection locked oscillator (ILO) of 35MHz frequency. Phase shifters at high frequencies are essential in many communication system applications such as frequency synthesis, quadrature signal generation and phase locked loops (PLLs).