Introduction Functional connectivity analysis has been used to map several consistent resting state networks by exploiting coherent low-frequency fluctuations in the BOLD signal. The assumption in most of the fMRI literature is that these correlated fluctuations are neuronal in origin. Others sources of low-frequency fluctuations exist in fMRI data that are unrelated to neuronal activity. These...

Fluctuations in the redshifted 21 centimeter emission from neutral hydrogen probe the epoch of reionization. We examine the observability of this signal and the impact of extragalactic foreground radio sources (both extended and point-like). We use cosmological simulations to predict the angular correlation functions of intensity fluctuations due to unresolved radio galaxies, cluster radio halo...

To assess the coherent detection of an optical signal perturbed by atmospheric turbulence, the loss in the mean signal-to-noise ratio (SNR) is usually invoked although it constitutes a limited description of the signal fluctuations. To produce statistical distributions of the SNR, we generate random optical fields. A 5/3-power law for the phase structure function is considered. The benefit of a...

Ultrasensitive cascades often implement thresholding operations in cell signaling and gene regulatory networks, converting graded input signals into discrete all-or-none outputs. However, the biochemical and genetic reactions involved in such cascades are subject to random fluctuations, leading to noise in output signal levels. Here we prove that cascades operating near saturation have output s...

Significant research efforts are being devoted to Body Area Networks (BAN) due to their potential for revolutionizing healthcare practices. Energy-efficiency and communication reliability are critically important for these networks. In an experimental study with three different mote platforms, we show that changes in human body shadowing as well as those in the relative distance and orientation...

Functional MRI (fMRI) has uncovered widespread hemodynamic fluctuations in the brain during rest. Recent electroencephalographic work in humans and microelectrode recordings in anesthetized monkeys have shown this activity to be correlated with slow changes in neural activity. Here we report that the spontaneous fluctuations in the local field potential (LFP) measured from a single cortical sit...

System configurations based on single monolithic-apertures that are immune to atmospheric fluctuations are being developed. Main goal is the improvement of the performance achievable in coherent, free-space optical communication systems using atmospheric compensation techniques such as adaptive optics. As an alternative to a single monolithicaperture coherent receiver with a full-size collectin...

In an open-air setting, one source of fluctuations in a T-ray (THz) pulsed signal is attributed to water vapor. Fluctuations of this type are generally undesired, and so the water vapor is commonly removed in a closed chamber. Yet, in some applications a closed chamber is not feasible. This paper presents a preliminary study on a computational means to address the problem. Initially, the comple...

The possibility of inferring the properties of electron density fluctuations in tokamak plasmas from a reflectometer signal by means of Bayesian methods is investigated. Within the physical optics approximation the interaction of the probing beam with the plasma is described as reflection from a surface with stochastic properties that is simulated numerically. A Bayesian technique is outlined t...

The last 500 million years of the strontium-isotope record are shown to correlate significantly with the concurrent record of isotopic fractionation between inorganic and organic carbon after the effects of recycled sediment are removed from the strontium signal. The correlation is shown to result from the common dependence of both signals on weathering and magmatic processes. Because the long-...