180 results for qubit oscillator frequency
Data from: Input-dependent frequency modulation of cortical gamma oscillations shapes spatial synchronization and enables phase coding
Contributors: Lowet, Eric, Roberts, Mark, Hadjipapas, Avgis, Peter, Alina, van der Eerden, Jan, De Weerd, Peter
phase-oscillator model part 1...phase-oscillator model part 2...phase-oscillator model part 3...phase-oscillator model part 4...oscillation frequencies at nearby spatial locations. Similarly to cortical...oscillation phase codes, may resolve conflicting experimental observations...frequency with increasing input drive. The relates to the experimental...oscillators. The gamma phase-locking, the precise phase relation and the...oscillators, where input drive determines the intrinsic (natural) frequency...Frequency Modulation of Cortical Gamma Oscillations Shapes Spatial Synchronization...oscillation...frequency of gamma oscillations varies with input drive (e.g. visual contrast ... Fine-scale temporal organization of cortical activity in the gamma range (~25–80Hz) may play a significant role in information processing, for example by neural grouping (‘binding’) and phase coding. Recent experimental studies have shown that the precise frequency of gamma oscillations varies with input drive (e.g. visual contrast) and that it can differ among nearby cortical locations. This has challenged theories assuming widespread gamma synchronization at a fixed common frequency. In the present study, we investigated which principles govern gamma synchronization in the presence of input-dependent frequency modulations and whether they are detrimental for meaningful input-dependent gamma-mediated temporal organization. To this aim, we constructed a biophysically realistic excitatory-inhibitory network able to express different oscillation frequencies at nearby spatial locations. Similarly to cortical networks, the model was topographically organized with spatially local connectivity and spatially-varying input drive. We analyzed gamma synchronization with respect to phase-locking, phase-relations and frequency differences, and quantified the stimulus-related information represented by gamma phase and frequency. By stepwise simplification of our models, we found that the gamma-mediated temporal organization could be reduced to basic synchronization principles of weakly coupled oscillators, where input drive determines the intrinsic (natural) frequency of oscillators. The gamma phase-locking, the precise phase relation and the emergent (measurable) frequencies were determined by two principal factors: the detuning (intrinsic frequency difference, i.e. local input difference) and the coupling strength. In addition to frequency coding, gamma phase contained complementary stimulus information. Crucially, the phase code reflected input differences, but not the absolute input level. This property of relative input-to-phase conversion, contrasting with latency codes or slower oscillation phase codes, may resolve conflicting experimental observations on gamma phase coding. Our modeling results offer clear testable experimental predictions. We conclude that input-dependency of gamma frequencies could be essential rather than detrimental for meaningful gamma-mediated temporal organization of cortical activity.
Contributors: Noah Phipps
Oscillations lab experiment....Oscillations, All Data.xlsx...Oscillation ... Data from a 1st Year Forced Oscillations lab experiment.
Contributors: Lowet, Eric, Roberts, Mark Jonathan, Peter, Alina, Gips, Bart, de Weerd, Peter
frequency modulations applies to gamma in V1, and is likely generalizable...frequency by increasing input current) and coupling on their phase dynamics...frequency difference. Crucially, the precise dynamics of frequencies and...frequencies. When similar enough, these frequencies continually attracted...oscillators influence each other’s phase relations. Hence, the fundamental...oscillators. With this code the effects of detuning and coupling are illustrated...oscillating neuronal populations to optimize information transmission ... Gamma-band synchronization coordinates brief periods of excitability in oscillating neuronal populations to optimize information transmission during sensation and cognition. Commonly, a stable, shared frequency over time is considered a condition for functional neural synchronization. Here, we demonstrate the opposite: instantaneous frequency modulations are critical to regulate phase relations and synchronization. In monkey visual area V1, nearby local populations driven by different visual stimulation showed different gamma frequencies. When similar enough, these frequencies continually attracted and repulsed each other, which enabled preferred phase relations to be maintained in periods of minimized frequency difference. Crucially, the precise dynamics of frequencies and phases across a wide range of stimulus conditions was predicted from a physics theory that describes how weakly coupled oscillators influence each other’s phase relations. Hence, the fundamental mathematical principle of synchronization through instantaneous frequency modulations applies to gamma in V1, and is likely generalizable to other brain regions and rhythms.
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A better oscillation detection method robustly extracts EEG rhythms across brain state changes: The human alpha rhythm as a test case
Contributors: Tara A. Whitten, Adam M. Hughes, Clayton T. Dickson, Jeremy B. Caplan
oscillation detection across frequency, region and task. Here we show ...oscillations at the alpha frequency (9.5Hz) highlighted in red, using ...OSCillation detection) method. This method produces systematic, objective...Oscillations detected across all frequencies by the oscillatory episode...oscillations were detected at each frequency. (E) The raw signal from ...Oscillation...frequencies, brain regions and tasks. It does so by modeling the functional ... Oscillatory activity is a principal mode of operation in the brain. Despite an intense resurgence of interest in the mechanisms and functions of brain rhythms, methods for the detection and analysis of oscillatory activity in neurophysiological recordings are still highly variable across studies. We recently proposed a method for detecting oscillatory activity from time series data, which we call the BOSC (Better OSCillation detection) method. This method produces systematic, objective, and consistent results across frequencies, brain regions and tasks. It does so by modeling the functional form of the background spectrum by fitting the empirically observed spectrum at the recording site. This minimizes bias in oscillation detection across frequency, region and task. Here we show that the method is also robust to dramatic changes in state that are known to influence the shape of the power spectrum, namely, the presence versus absence of the alpha rhythm, and can be applied to independent components, which are thought to reflect underlying sources, in addition to individual raw signals. This suggests that the BOSC method is an effective tool for measuring changes in rhythmic activity in the more common research scenario wherein state is unknown.
Transcription profiling by array of Arabidopsis seedlings response to three oscillating levels in cytosolic Ca2+
frequency low amplitude osc. One biological sample per experiment processed...oscillating elevations in cytosolic Ca2+ (created using electrical stimulation...frequency high amplitude osc., Treatment 2; high frequency low amplitude ... Comparison of 3 oscillating elevations in cytosolic Ca2+ (created using electrical stimulation and measured using aequorin luminescence) in Arabidopsis seedlings. Treatment 1; high frequency high amplitude osc., Treatment 2; high frequency low amplitude osc., Treatment 3; low frequency low amplitude osc. One biological sample per experiment processed as technical dye swaps against intreated control.
Effective oscillator strength distributions of spherically symmetric atoms for calculating polarizabilities and long-range atom–atom interactions
Contributors: Jun Jiang, J. Mitroy, Yongjun Cheng, M.W.J. Bromley
oscillator strength distributions. See explanation of tables. ...frequencies. These polarizabilities can be used to determine the long-range...oscillator strength distribution...oscillator strengths are fc(1), fc(2) and fc(3) respectively. ...oscillator strengths, i.e. for each multipole (fe1(ℓ),ϵe1(ℓ),fe2(ℓ),ϵe2...oscillator strength distributions are systematically generated and tabulated...oscillator strength distributions for all atoms or ions. k is the order...oscillator strength. ...Oscillator strength sum- rule ... Effective oscillator strength distributions are systematically generated and tabulated for the alkali atoms, the alkaline-earth atoms, the alkaline-earth ions, the rare gases and some miscellaneous atoms. These effective distributions are used to compute the dipole, quadrupole and octupole static polarizabilities, and are then applied to the calculation of the dynamic polarizabilities at imaginary frequencies. These polarizabilities can be used to determine the long-range C6, C8 and C10 atom–atom interactions for the dimers formed from any of these atoms and ions, and we present tables covering all of these combinations.
Transcription profiling by high throughput sequencing in PER2 mutant of human endometrial stromal cells
Contributors: Muter J, Lucas ES, Chan YW, Brighton PJ, Moore JD, Lacey L, Quenby S, Lam EW, Brosens JJ
oscillations are predicated on transcriptional-translational feedback ...oscillations in decidualizing human endometrial stromal cells (HESCs). ... Implantation is dependent on synchronized interactions between the conceptus and surrounding decidual cells but the involvement of clock genes in this process is not well understood. Circadian oscillations are predicated on transcriptional-translational feedback loops, which balance the activities of the transcriptional activators CLOCK and BMAL1 and repressors encoded by PER and CRY genes. Here we show that loss of PER2 expression silences circadian oscillations in decidualizing human endometrial stromal cells (HESCs). Downregulation was preceded by reduced CLOCK binding to a noncanonical E-box enhancer in the PER2 promoter and occurred between 12 - 24 h after exposure to a deciduogenic stimulus. RNA sequencing revealed that premature inhibition of PER2 by siRNA knockdown leads to a grossly disorganised decidual response. Gene ontology analysis highlighted a preponderance of cell cycle regulators amongst the 1,121 genes perturbed upon PER2 knockdown. Congruently, PER2 inhibition abrogated mitotic expansion of differentiating HESCs by inducing cell cycle block at G2/M. Analysis of mid-luteal endometrial biopsies revealed an inverse correlation between PER2 transcript levels and the number of miscarriages in women suffering reproductive failure. Thus, PER2 synchronizes mitotic expansion of HESCs with a periodic decidual gene expression; uncoupling of these events may cause persistent pregnancy failure. Endometrial mRNA profiles of paired control (siRNA-NT) and siRNA-PER2 were generated by deep sequencing, in triplicate using Illumina
Data from: Head movements quadruple the range of speeds encoded by the insect motion vision system in hawkmoths
Contributors: Windsor, Shane P., Taylor, Graham K.
oscillation amplitudes, oscillation frequencies, and spatial frequencies...frequency-domain system identification techniques to characterise the ... Flying insects use compensatory head movements to stabilize gaze. Like other optokinetic responses, these movements can reduce image displacement, motion, and misalignment, and simplify the optic flow field. Because gaze is imperfectly stabilized in insects, we hypothesised that compensatory head movements serve to extend the range of velocities of self-motion that the visual system encodes. We tested this by measuring head movements in hawkmoths Hyles lineata responding to full-field visual stimuli of differing oscillation amplitudes, oscillation frequencies, and spatial frequencies. We used frequency-domain system identification techniques to characterise the head's roll response, and simulated how this would have affected the output of the motion vision system, modelled as a computational array of Reichardt detectors. The moths' head movements were modulated to allow encoding of both fast and slow self-motion, effectively quadrupling the working range of the visual system for flight control. By using its own output to drive compensatory head movements, the motion vision system thereby works as an adaptive sensor, which will be most beneficial in nocturnal species with inherently slow vision. Studies of the ecology of motion vision must therefore consider the tuning of motion-sensitive interneurons in the context of the closed-loop systems in which they function.
Contributors: Curry, William B, Oppo, Delia W
oscillations in tropical SST is too large to have resulted from changes...oscillations in air temperature recorded in the Greenland and Antarctic...oscillations in surface water hydrography and deep water circulation occurring...high-frequency oscillations in tropical sea surface temperatures and North...oscillations in sea surface temperature in the equatorial Atlantic. The ... Abstract: Stable isotopic measurements of G. sacculifer and C. wuellerstorfi in a core from the western equatorial Atlantic imply that there are parallel, suborbital oscillations in surface water hydrography and deep water circulation occurring during oxygen isotope stages 2 and 3. Low values of G. sacculifer delta18O accompany high values of C. wuellerstorfi delta13C, linking warmer sea surface temperatures (SSTs) in the tropics with increased production of lower North Atlantic Deep Water (NADW). The amplitude of the delta18O oscillations is 0.6 per mil (or 2°-3°C), which is superimposed on a glacial/interglacial amplitude of about 2.1per mil. Using the G. sacculifer delta18O data, we calculate that surface waters were colder during stage 2 than calculated by CLIMAP [1976, 1981]. The longer-period (>2 kyr) oscillations in air temperature recorded in the Greenland and Antarctic ice cores appear to correlate with oscillations in sea surface temperature in the equatorial Atlantic. The magnitude of these oscillations in tropical SST is too large to have resulted from changes in meridional heat transport caused by the global conveyor alone. The apparent synchroneity of equatorial SST and polar air temperature changes, as well as the amplitude of the SST changes at the equator, are consistent with the climate effects expected from changes in the atmosphere's greenhouse gas content (H2Ovapor, CO2, and CH4). Category: geoscientificInformation Source: Supplement to: Curry, William B; Oppo, Delia W (1997): Synchronous, high-frequency oscillations in tropical sea surface temperatures and North Atlantic Deep Water productivity during the last glacial cycle. Paleoceanography, 12(1), 1-14, https://doi.org/10.1029/96PA02413 Supplemental Information: Not Availble Coverage: EVENT LABEL: * LATITUDE: 5.906700 * LONGITUDE: -44.195000 * ELEVATION START: -4056.0 m * ELEVATION END: 0.0 m * Recovery: 6 m * DEVICE: Piston corer
Measurements of 14NH3 in the ν2=1 state by a solid-state, photomixing, THz spectrometer, and a simultaneous analysis of the microwave, terahertz, and infrared transitions between the ground and ν2 inversion–rotation levels
Contributors: Pin Chen, J.C. Pearson, Herbert M. Pickett, Shuji Matsuura, Geoffrey A. Blake
oscillator power amplifier), and subsequently, the amplified beams pump...THz-frequencies without requiring accurate knowledge of the absolute laser...frequency sweep was performed by stepping the microwave sweeper frequency...frequency of 2MHz, a burst frequency of 8kHz, and a lock-in time-constant...frequencies and pressure shifts (where significant enough to be observed...difference-frequency spectrometer. Using an innovative laser-frequency...frequencies into the SPFIT spectral analysis program. ...frequencies and intensities for all possible transitions up to J=20 between...Frequency...frequencies. The details of the spectrometer’s frequency calibration is...frequencies and their pressure-shift parameters ... In this paper, we report 30THz measurements of ammonia in its excited, ν2=1, inversion state. These measurements include transition frequencies and pressure shifts (where significant enough to be observed). Included in the data are two forbidden and three ro-inversion transitions, as well as 18 transitions never directly measured before. The measurements were made with an all-solid-state, diode-laser, difference-frequency spectrometer. Using an innovative laser-frequency locking scheme, this spectrometer provided accurately determined and continuously tuned THz-frequencies without requiring accurate knowledge of the absolute laser frequencies. The details of the spectrometer’s frequency calibration is discussed. A global analysis of NH3 based on the available ground state, ν2=1 state, and ν2-band transitions was carried out, and the resulting set of recommended molecular effective-Hamiltonian parameters for ammonia is presented. In addition, calculated center frequencies and intensities for all possible transitions up to J=20 between rotation, inversion, and vibration levels in the ground and ν2=1 states are included as supplementary material.