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The vigilance decrement has been described as a slowing in reaction times or an increase in error rates as an effect of time-on-task during tedious monitoring tasks. This decrement has been alternatively ascribed to either withdrawal of the supervisory attentional system, due to underarousal caused by the insufficient workload, or to a decreased attentional(More)
To recreate stress in laboratory conditions, the nature of the elicited physiological reactions to the presentation of mental tasks has been extensively studied. However, whether this experimental response is equivalent to real-life stress reactivity is still under debate. We investigated cardio-respiratory reactivity to a sequential protocol of different(More)
We first generalize the concept of clutter power spectrum locus so that it can be applied to arbitrary antenna arrays. This locus is a curve in the 4D space of the Doppler frequency and the 3 spatial frequencies. This generalization is valid for both monostatic and bistatic radar configurations. We show that the customary clutter power spectrum locus(More)
In this paper, we examine the feasibility of applying Space-Time Adaptive Processing (STAP) to bistatic passive radars using illuminators of opportunity. The transmitters considered are GSM base stations and are non-cooperative. Although STAP has been extensively applied to signals from pulse-Doppler radars, it was never applied to arbitrary signals arising(More)
In this article, we investigated the hypothesis that the effects of hypergravity on respiratory sinus arrhythmia (RSA) can mimic the effects observed after spaceflight cardiovascular deconditioning. Artificial gravity along the head-to-feet axis on a short-arm centrifuge induces gravity gradients. This physiological condition of significantly higher g at(More)
The increasing interest for arbitrary antenna arrays in radar space-time adaptive processing (STAP) creates a need for a thorough understanding of the role of, and dependencies between, spatial and Doppler frequencies and related quantities, especially in the characterization of clutter. We successively introduce “geometrical” and statistical concepts,(More)
This study examined the existence of direct maternal-infant physiological relatedness in respiratory sinus arrhythmia (RSA) when the infant was age 1, 2, 4, 8, and 12 weeks. We instructed mothers to breathe at 6, 12, 15, 20, and 6 cycles per minute while their infants lay on their body. The mother-infant ECG and respiration were registered and video(More)
Unlike classical bistatic radars, passive radars make use of illuminators of opportunity to detect targets and to estimate target parameters. One existing radio transmission suitable for passive radar operation is the Global System for Mobile Communication (GSM). For non-cooperative bistatic configurations, one of the major difficulties is the estimation of(More)
Mitigation of radar ground clutter via STAP requires estimating the interference-plus-noise snapshot covariance matrix at each range. The typical approach is to average single-realization sample covariance matrices at neighboring ranges. However, in most configurations, snapshots have range-dependent spectral characteristics, leading to severe performance(More)