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The possibility of determining reactor subcriticality on the basis of spectral analysis of reactor noise taking into account spatial effects is considered. The proposed approach uses the model of an equivalent noise source, which ...
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The possibility of determining reactor subcriticality on the basis of spectral analysis of reactor noise taking into account spatial effects is considered. The proposed approach uses the model of an equivalent noise source, which in accordance with the Schottky formula includes reactivity and neutron adjoint flux factors determined directly from reactor noise measurements by the system of in-core detectors. The implementation of the methodology is illustrated by the example of a simple calculation model of a plane reactor.
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Resting fluctuations in arterial CO_2 (a cerebral vasodilator) are believed to be an important source of low-frequency blood oxygenation level dependent (BOLD) signal fluctuations. In this study we focus on the two commonly used r...
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Resting fluctuations in arterial CO_2 (a cerebral vasodilator) are believed to be an important source of low-frequency blood oxygenation level dependent (BOLD) signal fluctuations. In this study we focus on the two commonly used resting-states in functional magnetic resonance imaging experiments, eyes open and eyes closed, and quantify the degree to which measured spontaneous fluctuations in the partial pressure of end-tidal CO_2 (Pet_(co2)) relate to BOLD signal time series. A significantly longer latency of BOLD signal changes following Pet_(co2) fluctuations was found in the eyes closed condition compared to with eyes open, which may reveal different intrinsic vascular response delays in CO_2 reactivity or an alteration in the net BOLD signal arising from Pet_(co2) fluctuations and altered neural activity with eyes closed. By allowing a spatially varying time delay for the compensation of this temporal difference, a more spatially consistent CO_2 correlation map can be obtained. Finally, Granger-causality analysis demonstrated a "causal" relationship between Pet_(co2) and BOLD. The identified dominant Pet_(co2)→BOLD directional coupling supports the notion that Pet_(co2) fluctuations are indeed a cause of resting BOLD variance in the majority of subjects.
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The propagation of sound across closely coupled narrow rectangular cavities in an infinitely long duct is studied numerically using finite-element simulation and the method of mode matching in the present investigation. Sound freq...
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The propagation of sound across closely coupled narrow rectangular cavities in an infinitely long duct is studied numerically using finite-element simulation and the method of mode matching in the present investigation. Sound frequencies below the first cut-off frequency of the main duct are the focuses. Results show that the middle region of the coupled cavity section plays the most important role in affecting the spectral characteristics of sound transmission across the coupled cavities. It is also found that there exists a critical frequency above which a coupled cavity section can offer reasonably good sound transmission loss. In addition, similarity in this stopband cut-on frequency across coupled cavity sections of different dimensions is established empirically after the introduction of a new length scale. The corresponding frequencies of the symmetrical non-offset coupled cavity sections are also a vital parameter in the scaling. Two frameworks are developed to predict the stopband cut-on frequencies. Both of them are able to give predictions with accuracy to within engineering tolerance. (C) 2018 Elsevier Ltd. All rights reserved.
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The statistical properties of two classes of filters generalizing the median filter are considered. The two classes are the alpha-trimmed mean ( alpha -TM) filter and the standard type M(STM) filter, both of which are special case...
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The statistical properties of two classes of filters generalizing the median filter are considered. The two classes are the alpha-trimmed mean ( alpha -TM) filter and the standard type M(STM) filter, both of which are special cases of the L filter. Results are developed to quantify the white-noise suppression and edge-preservation characteristics of the filters by considering their output sequence error statistics. It is shown that the alpha -TM and STM filters perform better than the running mean and median filters in white noise suppression, while they can be designed to be comparable to the median filter in edge preservation in the presence of noise.
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We have studied the amplitude modulation (AM) and phase modulation (PM) noise in a number of 5 MHz and 100 MHz oscillators to provide a basis for developing models of the origin of AM noise. To adequately characterize the AM noise...
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We have studied the amplitude modulation (AM) and phase modulation (PM) noise in a number of 5 MHz and 100 MHz oscillators to provide a basis for developing models of the origin of AM noise. To adequately characterize the AM noise in high performance quartz oscillators, we found it necessary to use two-channel cross-correlation AM detection. In the quartz oscillators studied, the power spectral density (PSD) of the f/sup -1/ and f/sup 0/ regions of AM noise is closely related to that of the PM noise. The major difference between different oscillators of the same design depends on the flicker noise performance of the resonator. We therefore propose that the f/sup -1/ and f/sup 0/ regions of AM and PM noise arise from the same physical processes, probably originating in the sustaining amplifier.
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Very few studies were devoted to permanent effects of nocturnal railway noise on sleep and cardiovascular reactivity. We investigated the effects of nocturnal railway noise on sleep and cardiovascular response in young and middle-...
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Very few studies were devoted to permanent effects of nocturnal railway noise on sleep and cardiovascular reactivity. We investigated the effects of nocturnal railway noise on sleep and cardiovascular response in young and middle-aged adults living for many years either near a railway track or in a quiet area. Forty subjects (50% males) divided into two age groups (juniors: 26.2 ±3.6 and seniors: 56.2 ±4.2) participated in this experiment. Half of them lived near a railway track (RW group: 2.6 to 19 years) and the other half in a quiet environment (QE group: 8.1 to 14.2 years). After an adaptation night, all subjects underwent two nights in the laboratory: one control night and one noisy night (30 by-passes of a freight train). Sleep and cardiovascular modifications were assessed in response to noise. Sleep fragmentation indices were lower in RW subjects compared to QE whatever their age. In response to noise, there was a higher cardiovascular response rate to noise in RW juniors and a lower cardiovascular response rate in RW seniors compared to their age-paired QE counterparts. In conclusion, permanent exposure to nocturnal railway noise leads to decreased sleep fragmentation and to cardiovascular habituation. It is suggested that during the initial period experienced by residents living near railway tracks, nocturnal railway noise could induce a sensitization process on the autonomic response to noise reflecting a startle/defense reflex due to its functional significance, which progressively turns to habituation in the long-term if no adverse effect is experienced.
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The current-voltage characteristics measured over a wide temperature range are reported for HgCdTemid-wavelenth infrared n-on-p photodiodes fabricated using a novel junction formation technology. The planar homojunction device jun...
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The current-voltage characteristics measured over a wide temperature range are reported for HgCdTemid-wavelenth infrared n-on-p photodiodes fabricated using a novel junction formation technology. The planar homojunction device junctions were formed on LPE grown vacancy doped hGCdTe using a reactive ion etching (RIE) plasma induced conversion process. The zero bias dynamic resistance-junction area product, R_oA, was 4.6 x 10~7Ω cm~2 at 80 K and is comparable to the best planar diodes reported using conventional ion implantation junction formation technology. Arrhenius plots of R_oA exhibit an activation energy equal to the band gap, Eg, and show that the diodes are diffusion limited for temperatures >=135 K. A series of temperature dependent 1/f noise measurements were performed, indicating that the activation energy for 1/f noise noise in the region where the diodes are diffusion limited is 0.7 Eg. Energies close to this value have previously been associated with Hg vacancies in HgCdTe. These results are similar to those obtained from high quality HgCdTe photodiodes fabricated using mature ion implantation technology. However, the plasma based technology used in this work is significantly less complex and does not require any high temperature annealing steps.
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Fireworks are the most common cause of noise aversion in pet-dogs eliciting potentially severe and prolonged behavioural responses, yet owners rarely see treatment. This article discusses the scale of the problem, aetiology and di...
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Fireworks are the most common cause of noise aversion in pet-dogs eliciting potentially severe and prolonged behavioural responses, yet owners rarely see treatment. This article discusses the scale of the problem, aetiology and differentia diagnoses.By educating clients on prevention, management and modification 'o firework reactivity, an opportunity exists for registered veterinary nurses to improvi pet-dog welfare during firework season, and throughout the year.
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Aims Environmental stressors such as traffic noise represent a global threat, accounting for 1.6 million healthy life years lost annually in Western Europe. Therefore, the noise-associated health side effects must be effectively p...
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Aims Environmental stressors such as traffic noise represent a global threat, accounting for 1.6 million healthy life years lost annually in Western Europe. Therefore, the noise-associated health side effects must be effectively prevented or mitigated. Non-pharmacological interventions such as physical activity or a balanced healthy diet are effective due to the activation of the adenosine monophosphate-activated protein kinase (α1AMPK). Here, we investigated for the first time in a murine model of aircraft noise-induced vascular dysfunction the potential protective role of α1AMPK activated via exercise, intermittent fasting, and pharmacological treatment. Methods and results Wild-type (B6.Cg-Tg(Cdh5-cre)7Mlia/J) mice were exposed to aircraft noise [maximum sound pressure level of 85 dB(A), average sound pressure level of 72 dB(A)] for the last 4 days. The α1AMPK was stimulated by different protocols, including 5-aminoimidazole-4-carboxamide riboside application, voluntary exercise, and intermittent fasting. Four days of aircraft noise exposure produced significant endothelial dysfunction in wild-type mice aorta, mesenteric arteries, and retinal arterioles. This was associated with increased vascular oxidative stress and asymmetric dimethylarginine formation. The α1AMPK activation with all three approaches prevented endothelial dysfunction and vascular oxidative stress development, which was supported by RNA sequencing data. Endothelium-specific α1AMPK knockout markedly aggravated noise-induced vascular damage and caused a loss of mitigation effects by exercise or intermittent fasting. Conclusion Our results demonstrate that endothelial-specific α1AMPK activation by pharmacological stimulation, exercise, and intermittent fasting effectively mitigates noise-induced cardiovascular damage. Future population-based studies need to clinically prove the concept of exercise/fasting-mediated mitigation of transportation noise-associated disease. Lay summary Traffic noise, e.g. from aircraft, significantly contributes to an increased risk of cardiovascular or metabolic diseases in the general population by brain-dependent stress reactions leading to higher levels of circulating stress hormones and vasoconstrictors, all of which cause hypertension, oxidative stress, and inflammation. With the present experimental studies, we provide for the first time molecular mechanisms responsible for successful noise mitigation: 1. Physical exercise, intermittent fasting, and pharmacological activation of the adenosine monophosphate-activated protein kinase (AMPK), a metabolic master regulator protein, prevent cardiovascular damage caused by noise exposure, such as hypertension, endothelial dysfunction, and reactive oxygen species formation (e.g. free radicals) and inflammation. 2. These beneficial mitigation manoeuvers are secondary to an activation of the endothelial AMPK, thereby mimicking the antidiabetic drug metformin.
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This paper investigates the benefits of intentionally adding noise to a Bayesian estimator, which comprises a linear combination of a number of individual Bayesian estimators that are perturbed by mutually independent noise source...
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This paper investigates the benefits of intentionally adding noise to a Bayesian estimator, which comprises a linear combination of a number of individual Bayesian estimators that are perturbed by mutually independent noise sources and multiplied by a set
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