Spectral synthesis techniques often use the OverLap-Add method. But in the case of noise synthesis, both experiments and theory show that this method introduces intensity fluctuations which imply audible artifacts. We propose here new methods to avoid these variations. The first one consists in multiplying the resulting signal by another weighting window to compensate dynamic fluctuations. The ...

The stability of the random field Ising model (RFIM) against spin glass (SC) fluctuations, as investigated by Mézard and Young, is naturally expressed via Legendre transforms, stability being then associated with the non-negativeness of eigenvalues of trie inverse of a generalized SC susceptibility matrix. It is found that the signal for trie occurrence of the SC transition will manifest itself...

Quantum correlations among bright pump, signal, and idler beams produced by an optical parametric oscillator, all with different frequencies, are experimentally demonstrated. We show that the degree of entanglement between signal and idler fields is improved by using information on pump fluctuations. To our knowledge this is the first observation of three-color optical quantum correlations.

Purpose: Various noise sources affect BOLD fMRI time-courses and limit the benefits of high field fMRI. The aim of the present study was to investigate the contribution and the origin of non-thermal noise to fMRI signal fluctuations in the visual cortex at 7T during rest. The following noise sources were considered: 1) low frequency drifts; 2) effects related to the phase of respiration and car...

Voltammetry was used to monitor in rats changes in medial prefrontal cortex (PFC) dopamine (DA) levels associated with response-contingent presentation of a condensed milk reward. During two initial training sessions, minor DA signal fluctuations were seen when animals consumed a standard 30 sec (0.2 ml) meal earned on a continuous reinforcement schedule. There was no evidence of experience-dep...

The influence of the global average signal (GAS) on functional-magnetic resonance imaging (fMRI)-based resting-state functional connectivity is a matter of ongoing debate. The global average fluctuations increase the correlation between functional systems beyond the correlation that reflects their specific functional connectivity. Hence, removal of the GAS is a common practice for facilitating ...

We consider the polarization of 21cm line radiation from the epoch of reionization due to both intrinsically polarized emission and secondary mechanisms. We argue that Thomson scattering of the 21cm quadrupole by the reionized universe is likely to produce the largest effect. The 21cm quadrupole is sourced by baryonic density fluctuations and the fluctuations in the ionization fraction due to d...

It is well known that magnetic resonance magnitude image data obey a Rician distribution. Unlike additive Gaussian noise, Rician "noise" is signal-dependent, and separating signal from noise is a difficult task. Rician noise is especially problematic in low signal-to-noise ratio (SNR) regimes where it not only causes random fluctuations, but also introduces a signal-dependent bias to the data t...

Many models of early structure formation predict a period of heating immediately preceding reionization, when X-rays raise the gas temperature above that of the cosmic microwave background. These X-rays are often assumed to heat the intergalactic medium (IGM) uniformly, but in reality will heat the gas more strongly closer to the sources. We develop a framework for calculating fluctuations in t...