Hypermedicalization in White Noise.
Benson, Josef
2015-09-01
The Nazis hijacked Germany's medical establishment and appropriated medical language to hegemonize their ideology. In White Noise, shifting medical information stifles the public into docility. In Nazi Germany the primacy of language and medical authority magnified the importance of academic doctors. The muddling of identities caused complex insecurities and the need for psychological doubles. In White Noise, Professor Gladney is driven by professional insecurities to enact a double in Murray. Through the manipulation of language and medical overreach the U.S., exemplified in the novel White Noise, has become a hypermedicalized society where the spirit of the Hippocratic Oath has eroded.
Schürmann, Michael
1993-01-01
Stochastic processes with independent increments on a group are generalized to the concept of "white noise" on a Hopf algebra or bialgebra. The main purpose of the book is the characterization of these processes as solutions of quantum stochastic differential equations in the sense of R.L. Hudsonand K.R. Parthasarathy. The notes are a contribution to quantum probability but they are also related to classical probability, quantum groups, and operator algebras. The Az ma martingales appear as examples of white noise on a Hopf algebra which is a deformation of the Heisenberg group. The book will be of interest to probabilists and quantum probabilists. Specialists in algebraic structures who are curious about the role of their concepts in probablility theory as well as quantum theory may find the book interesting. The reader should havesome knowledge of functional analysis, operator algebras, and probability theory.
Spectrophotometry of white dwarfs as observed at high signal-to-noise ratio. II
International Nuclear Information System (INIS)
Greenstein, J.L.; Liebert, J.W.
1990-01-01
CCD spectrophotometry is presented of 140 white dwarfs at high SNR and is analyzed in detail. Energy distributions at 14,000 A are given at bandpasses from 3571 to 8300 A, and equivalent widths of lines of H, He I, metals, and atomic and molecular carbon are given as functions of color for DB, DQ, DZ, and DA stars. New forbidden H I transitions at 6068 A and 6632 A are found in at least the two hottest DB stars, new metallic features are found in cooler DZ stars, and the presence of Ca I in vMa 2 is confirmed. The spectrum of the hot DQAB star G227 - 5 and the pressure-shifted carbon bands seen in 0038-226 are discussed in detail. Comparison of the optical energy distribution of the latter with published IR fluxes shows that the 1-2 micron region is strongly depressed, with extensive blanketing. Equivalent widths, central depths, and width parameters are presented for H-alpha in 73 DA stars in the sample, and their dependences on color are studied. 64 refs
Noise frame duration, masking potency and whiteness of temporal noise
Kukkonen, Helja; Rovamo, Jyrki; Donner, Kristian; Tammikallio, Marja; Raninen, Antii
2002-01-01
PURPOSE. Because of the limited contrast range, increasing the duration of the noise frame is often the only option for increasing the masking potency of external, white temporal noise. This, however, reduces the high-frequency cutoff beyond which noise is no longer white. This study was conducted to determine the longest noise frame duration that produces the strongest masking effect and still mimics white noise on the detection of sinusoidal flicker. \\ud \\ud METHODS. Contrast energy thresho...
Eckstein, M. P.; Ahumada, A. J. Jr; Watson, A. B.
1997-01-01
Studies of visual detection of a signal superimposed on one of two identical backgrounds show performance degradation when the background has high contrast and is similar in spatial frequency and/or orientation to the signal. To account for this finding, models include a contrast gain control mechanism that pools activity across spatial frequency, orientation and space to inhibit (divisively) the response of the receptor sensitive to the signal. In tasks in which the observer has to detect a known signal added to one of M different backgrounds grounds due to added visual noise, the main sources of degradation are the stochastic noise in the image and the suboptimal visual processing. We investigate how these two sources of degradation (contrast gain control and variations in the background) interact in a task in which the signal is embedded in one of M locations in a complex spatially varying background (structured background). We use backgrounds extracted from patient digital medical images. To isolate effects of the fixed deterministic background (the contrast gain control) from the effects of the background variations, we conduct detection experiments with three different background conditions: (1) uniform background, (2) a repeated sample of structured background, and (3) different samples of structured background. Results show that human visual detection degrades from the uniform background condition to the repeated background condition and degrades even further in the different backgrounds condition. These results suggest that both the contrast gain control mechanism and the background random variations degrade human performance in detection of a signal in a complex, spatially varying background. A filter model and added white noise are used to generate estimates of sampling efficiencies, an equivalent internal noise, an equivalent contrast-gain-control-induced noise, and an equivalent noise due to the variations in the structured background.
White noise excitation in a hot plasma
International Nuclear Information System (INIS)
Ito, Masataka
1977-01-01
In a low frequency range, a property of white noise in a hot plasma is studied experimentally. A frequency component of white noise is observed to propagate with a phase velocity which is equal to the ion accoustic wave velocity. The white noise, which is launched in a plasma, is considered as the sum of ion acoustic waves. (auth.)
Complexity in White Noise Analysis
Hida, Takeyuki
We restrict our attention to random complex systems and discuss degree their degree of complexity based on a white noise. The white noise is realized as the time derivative of a Brownian motion B(t), and denoted by Ḃ(t). The collection {Ḃ(t)}, is a system of idealized elementary variables and at the same time the system is a stochastic representation of the time t, in other words it is time-oriented. Having expressed the given evolutional random phenomena in question in terms of the Ḃ(t), we introduce the notion of spectral multiplicity, which describes how much the phenomena are complex. The multiplicity is the number of cyclic subspaces that are spanned by the given random phenomena. Each cyclic subspace has further structure. Typical property is multiple Markov property, although this property appears only particular cases. As a related property, in fact as a characteristic of a complex system, one can speak of the time reversibility and irreversibility of certain random phenomena in terms of the white noise. We expect an irreversible random complex system may be decomposed into reversible systems.
Noise frame duration, masking potency and whiteness of temporal noise.
Kukkonen, Heljä; Rovamo, Jyrki; Donner, Kristian; Tammikallio, Marja; Raninen, Antti
2002-09-01
Because of the limited contrast range, increasing the duration of the noise frame is often the only option for increasing the masking potency of external, white temporal noise. This, however, reduces the high-frequency cutoff beyond which noise is no longer white. This study was conducted to determine the longest noise frame duration that produces the strongest masking effect and still mimics white noise on the detection of sinusoidal flicker. Contrast energy thresholds (E(th)) were measured for flicker at 1.25 to 20 Hz in strong, purely temporal (spatially uniform), additive, external noise. The masking power of white external noise, characterized by its spectral density at zero frequency N0, increases with the duration of the noise frame. For short noise frame durations, E(th) increased in direct proportion to N0, keeping the nominal signal-to-noise ratio [SNR = (E(th)/N0)(0.5)] constant at threshold. The masking effect thus increased with the duration of the noise frame and the noise mimicked white noise. When noise frame duration and N0 increased further, the nominal SNR at threshold started to decrease, indicating that noise no longer mimicked white noise. The minimum number of noise frames per flicker cycle needed to mimic white noise decreased with increasing flicker frequency from 8.3 at 1.25 Hz to 1.6 at 20 Hz. The critical high-frequency cutoff of detection-limiting temporal noise in terms of noise frames per signal cycle depends on the temporal frequency of the signal. This is opposite to the situation in the spatial domain and must be taken into consideration when temporal signals are masked with temporal noise.
Numerical methods for stochastic partial differential equations with white noise
Zhang, Zhongqiang
2017-01-01
This book covers numerical methods for stochastic partial differential equations with white noise using the framework of Wong-Zakai approximation. The book begins with some motivational and background material in the introductory chapters and is divided into three parts. Part I covers numerical stochastic ordinary differential equations. Here the authors start with numerical methods for SDEs with delay using the Wong-Zakai approximation and finite difference in time. Part II covers temporal white noise. Here the authors consider SPDEs as PDEs driven by white noise, where discretization of white noise (Brownian motion) leads to PDEs with smooth noise, which can then be treated by numerical methods for PDEs. In this part, recursive algorithms based on Wiener chaos expansion and stochastic collocation methods are presented for linear stochastic advection-diffusion-reaction equations. In addition, stochastic Euler equations are exploited as an application of stochastic collocation methods, where a numerical compa...
Facilitation of Retention by White Noise
Baumeister, Alfred A.; Kistler, Doris
1975-01-01
This study attempted to determine if white noise (an arousing stimulus), when presented at the time of recall, facilitates performance of second and fifth grade students, and if this effect generalizes across different kinds of learning tasks. Findings indicate that white noise produces improvements in performance in both age groups. (GO)
High level white noise generator
International Nuclear Information System (INIS)
Borkowski, C.J.; Blalock, T.V.
1979-01-01
A wide band, stable, random noise source with a high and well-defined output power spectral density is provided which may be used for accurate calibration of Johnson Noise Power Thermometers (JNPT) and other applications requiring a stable, wide band, well-defined noise power spectral density. The noise source is based on the fact that the open-circuit thermal noise voltage of a feedback resistor, connecting the output to the input of a special inverting amplifier, is available at the amplifier output from an equivalent low output impedance caused by the feedback mechanism. The noise power spectral density level at the noise source output is equivalent to the density of the open-circuit thermal noise or a 100 ohm resistor at a temperature of approximately 64,000 Kelvins. The noise source has an output power spectral density that is flat to within 0.1% (0.0043 db) in the frequency range of from 1 KHz to 100 KHz which brackets typical passbands of the signal-processing channels of JNPT's. Two embodiments, one of higher accuracy that is suitable for use as a standards instrument and another that is particularly adapted for ambient temperature operation, are illustrated in this application
High level white noise generator
Borkowski, Casimer J.; Blalock, Theron V.
1979-01-01
A wide band, stable, random noise source with a high and well-defined output power spectral density is provided which may be used for accurate calibration of Johnson Noise Power Thermometers (JNPT) and other applications requiring a stable, wide band, well-defined noise power spectral density. The noise source is based on the fact that the open-circuit thermal noise voltage of a feedback resistor, connecting the output to the input of a special inverting amplifier, is available at the amplifier output from an equivalent low output impedance caused by the feedback mechanism. The noise power spectral density level at the noise source output is equivalent to the density of the open-circuit thermal noise or a 100 ohm resistor at a temperature of approximately 64,000 Kelvins. The noise source has an output power spectral density that is flat to within 0.1% (0.0043 db) in the frequency range of from 1 KHz to 100 KHz which brackets typical passbands of the signal-processing channels of JNPT's. Two embodiments, one of higher accuracy that is suitable for use as a standards instrument and another that is particularly adapted for ambient temperature operation, are illustrated in this application.
White noise calculus and Fock space
Obata, Nobuaki
1994-01-01
White Noise Calculus is a distribution theory on Gaussian space, proposed by T. Hida in 1975. This approach enables us to use pointwise defined creation and annihilation operators as well as the well-established theory of nuclear space.This self-contained monograph presents, for the first time, a systematic introduction to operator theory on fock space by means of white noise calculus. The goal is a comprehensive account of general expansion theory of Fock space operators and its applications. In particular,first order differential operators, Laplacians, rotation group, Fourier transform and their interrelations are discussed in detail w.r.t. harmonic analysis on Gaussian space. The mathematical formalism used here is based on distribution theory and functional analysis , prior knowledge of white noise calculus is not required.
Collapse models with non-white noises
International Nuclear Information System (INIS)
Adler, Stephen L; Bassi, Angelo
2007-01-01
We set up a general formalism for models of spontaneous wavefunction collapse with dynamics represented by a stochastic differential equation driven by general Gaussian noises, not necessarily white in time. In particular, we show that the non-Schroedinger terms of the equation induce the collapse of the wavefunction to one of the common eigenstates of the collapsing operators, and that the collapse occurs with the correct quantum probabilities. We also develop a perturbation expansion of the solution of the equation with respect to the parameter which sets the strength of the collapse process; such an approximation allows one to compute the leading-order terms for the deviations of the predictions of collapse models with respect to those of standard quantum mechanics. This analysis shows that to leading order, the 'imaginary noise' trick can be used for non-white Gaussian noise
Renormalized powers of quantum white noise
International Nuclear Information System (INIS)
Accardi, L.; Boukas, A.
2009-01-01
Giving meaning to the powers of the creation and annihilation densities (quantum white noise) is an old and important problem in quantum field theory. In this paper we present an account of some new ideas that have recently emerged in the attempt to solve this problem. We emphasize the connection between the Lie algebra of the renormalized higher powers of quantum white noise (RHPWN), which can be interpreted as a suitably deformed (due to renormalization) current algebra over the 1-mode full oscillator algebra, and the current algebra over the centerless Virasoro (or Witt)-Zamolodchikov-ω ∞ Lie algebras of conformal field theory. Through a suitable definition of the action on the vacuum vector we describe how to obtain a Fock representation of all these algebras. We prove that the restriction of the vacuum to the abelian subalgebra generated by the field operators gives an infinitely divisible process whose marginal distribution is the beta (or continuous binomial). (authors)
Frank, David W; Yee, Ryan B; Polich, John
2012-08-01
P3a and P3b event-related brain potentials (ERPs) were elicited with an auditory three-stimulus (target, distracter, and standard) discrimination task in which subjects responded only to the target. Distracter stimuli consisted of white noise or novel sounds with stimulus characteristics perceptually matched. Target/standard discrimination difficulty was manipulated by varying target/standard pitch differences to produce relatively easy, medium, and hard tasks. Error rate and response time increased with increases in task difficulty. P3a was larger for the white noise compared to novel sounds, maximum over the central/parietal recording sites, and did not differ in size across difficulty levels. P3b was unaffected by distracter type, decreased as task difficulty increased, and maximum over the parietal recording sites. The findings indicate that P3a from white noise is robust and should be useful for applied studies as it removes stimulus novelty variability. Theoretical perspectives are discussed. Copyright © 2012 Elsevier B.V. All rights reserved.
White Gaussian Noise - Models for Engineers
Jondral, Friedrich K.
2018-04-01
This paper assembles some information about white Gaussian noise (WGN) and its applications. It starts from a description of thermal noise, i. e. the irregular motion of free charge carriers in electronic devices. In a second step, mathematical models of WGN processes and their most important parameters, especially autocorrelation functions and power spectrum densities, are introduced. In order to proceed from mathematical models to simulations, we discuss the generation of normally distributed random numbers. The signal-to-noise ratio as the most important quality measure used in communications, control or measurement technology is accurately introduced. As a practical application of WGN, the transmission of quadrature amplitude modulated (QAM) signals over additive WGN channels together with the optimum maximum likelihood (ML) detector is considered in a demonstrative and intuitive way.
Stability under persistent perturbation by white noise
International Nuclear Information System (INIS)
Kalyakin, L
2014-01-01
Deterministic dynamical system which has an asymptotical stable equilibrium is considered under persistent perturbation by white noise. It is well known that if the perturbation does not vanish in the equilibrium position then there is not Lyapunov's stability. The trajectories of the perturbed system diverge from the equilibrium to arbitrarily large distances with probability 1 in finite time. New concept of stability on a large time interval is discussed. The length of interval agrees the reciprocal quantity of the perturbation parameter. The measure of stability is the expectation of the square distance from the trajectory till the equilibrium position. The method of parabolic equation is applied to both estimate the expectation and prove such stability. The main breakthrough is the barrier function derived for the parabolic equation. The barrier is constructed by using the Lyapunov function of the unperturbed system
Introducing the White Noise task in childhood
DEFF Research Database (Denmark)
Rimvall, M K; Clemmensen, L; Munkholm, A
2016-01-01
the Kiddie-SADS-PL. Register data described family history of mental disorders. Exaggerated Theory of Mind functioning (hyper-ToM) was measured by the ToM Storybook Frederik. A total of 145 (10%) children experienced speech illusions (hearing speech in the absence of speech stimuli), of which 102 (70......Auditory verbal hallucinations (AVH) are common during development and may arise due to dysregulation in top-down processing of sensory input. This study was designed to examine the frequency and correlates of speech illusions measured using the White Noise (WN) task in children from the general...... population. Associations between speech illusions and putative risk factors for psychotic disorder and negative affect were examined. A total of 1486 children aged 11–12 years of the Copenhagen Child Cohort 2000 were examined with the WN task. Psychotic experiences and negative affect were determined using...
White noise theory of robust nonlinear filtering with correlated state and observation noises
Bagchi, Arunabha; Karandikar, Rajeeva
1992-01-01
In the direct white noise theory of nonlinear filtering, the state process is still modeled as a Markov process satisfying an Ito stochastic differential equation, while a finitely additive white noise is used to model the observation noise. In the present work, this asymmetry is removed by modeling
White noise theory of robust nonlinear filtering with correlated state and observation noises
Bagchi, Arunabha; Karandikar, Rajeeva
1994-01-01
In the existing `direct¿ white noise theory of nonlinear filtering, the state process is still modelled as a Markov process satisfying an Itô stochastic differential equation, while a `finitely additive¿ white noise is used to model the observation noise. We remove this asymmetry by modelling the
Some recent results in finitely additive white noise theory
Bagchi, Arunabha; Mazumdar, Ravi
1994-01-01
We present a short survey of some very recent results on the finitely additive white noise theory. We discuss the Markov property of the solution of a stochastic differential equation driven directly by a white noise, study the Radon-Nikodym derivative of the measure induced by nonlinear
Masking potency and whiteness of noise at various noise check sizes.
Kukkonen, H; Rovamo, J; Näsänen, R
1995-02-01
The masking effect of spatial noise can be increased by increasing either the rms contrast or check size of noise. In this study, the authors investigated the largest noise check size that still mimics the effect of white noise in grating detection and how it depends on the bandwidth and spatial frequency of a grating. The authors measured contrast energy thresholds, E, for vertical cosine gratings at various spatial frequencies and bandwidths. Gratings were embedded in two-dimensional spatial noise. The side length of the square noise checks was varied in the experiments. The spectral density, N(0,0), of white spatial noise at zero frequency was calculated by multiplying the noise check area by the rms contrast of noise squared. The physical signal-to-noise ratio at threshold [E/N(0,0)]0.5 was initially constant but then started to decrease. The largest noise check that still produced a constant physical signal-to-noise ratio at threshold was directly proportional to the spatial frequency. When expressed as a fraction of grating cycle, the largest noise check size depended only on stimulus bandwidth. The smallest number of noise checks per grating cycle needed to mimic the effect of white noise decreased from 4.2 to 2.6 when the number of grating cycles increased from 1 to 64. Spatial noise can be regarded as white in grating detection if there are at least four square noise checks per grating cycle at all spatial frequencies.
Differential effects of white noise in cognitive and perceptual tasks
Herweg, Nora A.; Bunzeck, Nico
2015-01-01
Beneficial effects of noise on higher cognition have recently attracted attention. Hypothesizing an involvement of the mesolimbic dopamine system and its functional interactions with cortical areas, the current study aimed to demonstrate a facilitation of dopamine-dependent attentional and mnemonic functions by externally applying white noise in five behavioral experiments including a total sample of 167 healthy human subjects. During working memory, acoustic white noise impaired accuracy whe...
Stochastic systems with cross-correlated Gaussian white noises
International Nuclear Information System (INIS)
Wang Cheng-Yu; Song Yu-Min; Zhou Peng; Yang Hai; Gao Yun
2010-01-01
This paper theoretically investigates three stochastic systems with cross-correlation Gaussian white noises. Both steady state properties of the stochastic nonlinear systems and the nonequilibrium transitions induced by the cross-correlated noises are studied. The stationary solutions of the Fokker—Planck equation for three specific examples are analysed. It is shown explicitly that the cross-correlation of white noises can induce nonequilibrium transitions
White noise enhances new-word learning in healthy adults.
Angwin, Anthony J; Wilson, Wayne J; Arnott, Wendy L; Signorini, Annabelle; Barry, Robert J; Copland, David A
2017-10-12
Research suggests that listening to white noise may improve some aspects of cognitive performance in individuals with lower attention. This study investigated the impact of white noise on new word learning in healthy young adults, and whether this effect was mediated by executive attention skills. Eighty participants completed a single training session to learn the names of twenty novel objects. The session comprised 5 learning phases, each followed by a recall test. A final recognition test was also administered. Half the participants listened to white noise during the learning phases, and half completed the learning in silence. The noise group demonstrated superior recall accuracy over time, which was not impacted by participant attentional capacity. Recognition accuracy was near ceiling for both groups. These findings suggest that white noise has the capacity to enhance lexical acquisition.
Absolute negative mobility induced by white Poissonian noise
International Nuclear Information System (INIS)
Spiechowicz, J; Łuczka, J; Hänggi, P
2013-01-01
We study the transport properties of inertial Brownian particles which move in a symmetric periodic potential and are subjected to both a symmetric, unbiased time-periodic external force and a biased Poissonian white shot noise (of non-zero average F) which is composed of a random sequence of δ-shaped pulses with random amplitudes. Upon varying the parameters of the white shot noise, one can conveniently manipulate the transport direction and the overall nonlinear response behavior. We find that within tailored parameter regimes the response is opposite to the applied average bias F of such white shot noise. This particular transport characteristic thus mimics that of a nonlinear absolute negative mobility (ANM) regime. Moreover, such white shot noise driven ANM is robust with respect to the statistics of the shot noise spikes. Our findings can be checked and corroborated experimentally by the use of a setup that consists of a single resistively and capacitively shunted Josephson junction device. (paper)
International Nuclear Information System (INIS)
Zhou Bingchang; Xu Wei
2008-01-01
The phenomenon of stochastic resonance (SR) in a bistable system driven by multiplicative colored and additive white noises and a periodic rectangular signal with a constant component is studied by using the unified colored noise approximation and the theory of signal-to-noise (SNR) in the adiabatic limit. The analytic expression of the SNR is obtained for arbitrary signal amplitude without being restricted to small amplitudes. The SNR is a non-monotonic function of intensities of multiplicative colored and additive white noises and correlation time of multiplicative colored noise, so SR exhibits in the bistable system. The effects of potential asymmetry r and correlation time τ of multiplicative colored noise on SNR are opposite. Moreover, It is more sensitive to control SR through adjusting the additive white noise intensity D than adjusting the multiplicative colored noise intensity Q
Differential effects of white noise in cognitive and perceptual tasks
Directory of Open Access Journals (Sweden)
Nora Alicia Herweg
2015-11-01
Full Text Available Beneficial effects of noise on higher cognition have recently attracted attention. Hypothesizing an involvement of the mesolimbic dopamine system and its functional interactions with cortical areas, the current study aimed to demonstrate a facilitation of dopamine-dependent attentional and mnemonic functions by externally applying white noise in five behavioral experiments including a total sample of 167 healthy human subjects. During working memory, acoustic white noise impaired accuracy when presented during the maintenance period (experiment 1-3. In a reward based long-term memory task, white noise accelerated perceptual judgments for scene images during encoding but left subsequent recognition memory unaffected (experiment 4. In a modified Posner task (experiment 5, the benefit due to white noise in attentional orienting correlated weakly with reward dependence, a personality trait that has been associated with the dopaminergic system. These results suggest that white noise has no general effect on cognitive functions. Instead, they indicate differential effects on perception and cognition depending on a variety of factors such as task demands and timing of white noise presentation.
Differential effects of white noise in cognitive and perceptual tasks.
Herweg, Nora A; Bunzeck, Nico
2015-01-01
Beneficial effects of noise on higher cognition have recently attracted attention. Hypothesizing an involvement of the mesolimbic dopamine system and its functional interactions with cortical areas, the current study aimed to demonstrate a facilitation of dopamine-dependent attentional and mnemonic functions by externally applying white noise in five behavioral experiments including a total sample of 167 healthy human subjects. During working memory, acoustic white noise impaired accuracy when presented during the maintenance period (Experiments 1-3). In a reward based long-term memory task, white noise accelerated perceptual judgments for scene images during encoding but left subsequent recognition memory unaffected (Experiment 4). In a modified Posner task (Experiment 5), the benefit due to white noise in attentional orienting correlated weakly with reward dependence, a personality trait that has been associated with the dopaminergic system. These results suggest that white noise has no general effect on cognitive functions. Instead, they indicate differential effects on perception and cognition depending on a variety of factors such as task demands and timing of white noise presentation.
Guo, Yongfeng; Shen, Yajun; Tan, Jianguo
2016-09-01
The phenomenon of stochastic resonance (SR) in a piecewise nonlinear model driven by a periodic signal and correlated noises for the cases of a multiplicative non-Gaussian noise and an additive Gaussian white noise is investigated. Applying the path integral approach, the unified colored noise approximation and the two-state model theory, the analytical expression of the signal-to-noise ratio (SNR) is derived. It is found that conventional stochastic resonance exists in this system. From numerical computations we obtain that: (i) As a function of the non-Gaussian noise intensity, the SNR is increased when the non-Gaussian noise deviation parameter q is increased. (ii) As a function of the Gaussian noise intensity, the SNR is decreased when q is increased. This demonstrates that the effect of the non-Gaussian noise on SNR is different from that of the Gaussian noise in this system. Moreover, we further discuss the effect of the correlation time of the non-Gaussian noise, cross-correlation strength, the amplitude and frequency of the periodic signal on SR.
White noise enhances new-word learning in healthy adults
Angwin, Anthony J.; Wilson, Wayne J.; Arnott, Wendy L.; Signorini, Annabelle; Barry, Robert J.; Copland, David A.
2017-01-01
Research suggests that listening to white noise may improve some aspects of cognitive performance in individuals with lower attention. This study investigated the impact of white noise on new word learning in healthy young adults, and whether this effect was mediated by executive attention skills. Eighty participants completed a single training session to learn the names of twenty novel objects. The session comprised 5 learning phases, each followed by a recall test. A final recognition test ...
White matter abnormalities of microstructure and physiological noise in schizophrenia.
Cheng, Hu; Newman, Sharlene D; Kent, Jerillyn S; Bolbecker, Amanda; Klaunig, Mallory J; O'Donnell, Brian F; Puce, Aina; Hetrick, William P
2015-12-01
White matter abnormalities in schizophrenia have been revealed by many imaging techniques and analysis methods. One of the findings by diffusion tensor imaging is a decrease in fractional anisotropy (FA), which is an indicator of white matter integrity. On the other hand, elevation of metabolic rate in white matter was observed from positron emission tomography (PET) studies. In this report, we aim to compare the two structural and functional effects on the same subjects. Our comparison is based on the hypothesis that signal fluctuation in white matter is associated with white matter functional activity. We examined the variance of the signal in resting state fMRI and found significant differences between individuals with schizophrenia and non-psychiatric controls specifically in white matter tissue. Controls showed higher temporal signal-to-noise ratios clustered in regions including temporal, frontal, and parietal lobes, cerebellum, corpus callosum, superior longitudinal fasciculus, and other major white matter tracts. These regions with higher temporal signal-to-noise ratio agree well with those showing higher metabolic activity reported by studies using PET. The results suggest that individuals with schizophrenia tend to have higher functional activity in white matter in certain brain regions relative to healthy controls. Despite some overlaps, the distinct regions for physiological noise are different from those for FA derived from diffusion tensor imaging, and therefore provide a unique angle to explore potential mechanisms to white matter abnormality.
The impact of auditory white noise on semantic priming.
Angwin, Anthony J; Wilson, Wayne J; Copland, David A; Barry, Robert J; Myatt, Grace; Arnott, Wendy L
2018-04-10
It has been proposed that white noise can improve cognitive performance for some individuals, particularly those with lower attention, and that this effect may be mediated by dopaminergic circuitry. Given existing evidence that semantic priming is modulated by dopamine, this study investigated whether white noise can facilitate semantic priming. Seventy-eight adults completed an auditory semantic priming task with and without white noise, at either a short or long inter-stimulus interval (ISI). Measures of both direct and indirect semantic priming were examined. Analysis of the results revealed significant direct and indirect priming effects at each ISI in noise and silence, however noise significantly reduced the magnitude of indirect priming. Analyses of subgroups with higher versus lower attention revealed a reduction to indirect priming in noise relative to silence for participants with lower executive and orienting attention. These findings suggest that white noise focuses automatic spreading activation, which may be driven by modulation of dopaminergic circuitry. Copyright © 2018 Elsevier Inc. All rights reserved.
White noise solutions to the stochastic mKdV equation
International Nuclear Information System (INIS)
Zhang Zhongjun; Wei Caimin
2009-01-01
In this paper, we present the white noise solutions of the stochastic mKdV equation via the Hermite transformation and variable-coefficient generalized projected Ricatti equation expansion method. These solutions include white noise solitary wave solutions, white noise soliton-like solutions and white noise trigonometric function solutions.
Bell's inequalities for three-qubit entangled states with white noise
International Nuclear Information System (INIS)
Chang, Jinho; Kwon, Younghun
2009-01-01
We consider three-qubit entangled states classified by Acin et al. and evaluate Bell's inequalities for them when the white noise exists, which may be a real situation for the experiment of the Bells inequality to three-qubit entangled states. We obtain the maximum violation for the Bell inequality in each case and find the condition for exceeding the classical limit. And we observe that even when there would exist quite amount of white noise, some of three-qubit entangled states(for example 2b, 3a, 3b-I, 3b-II and 3b-III types) might show the violation of the Bell inequality.
Phenomenon of entropic stochastic resonance with asymmetric dichotomous noise and white noise
International Nuclear Information System (INIS)
Guo, Feng; Li, Shao-Fu; Cheng, Xiao-Feng
2012-01-01
The entropic stochastic resonance (ESR) in a confined system subject to asymmetric dichotomous noise, white noise, and a periodic square-wave signal is investigated. Under the adiabatic approximation condition, by use of the properties of the dichotomous noise, we obtain the expression of the output signal-to-noise ratio (SNR) based on two-state theory. The SNR is shown to be a nonmonotonic function of the strength and asymmetry of the dichotomous noise, the intensity of the white noise, and the amplitude of the square-wave signal. The SNR varies non-monotonically with increases in the parameters of the confined structure. The influence of the correlation rate of the dichotomous noise and the frequency of the external constant force on the SNR is also discussed.
Study of white noise; Hakushoku zatsuon ni kansuru ichikosatsu
Energy Technology Data Exchange (ETDEWEB)
Kano, R; Tada, R [Teikoku Oil Co. Ltd., Tokyo (Japan)
1996-05-01
A study was made on conditions available for white noise belonging to a finite power function with the use of a power spectrum conception. It was defined that a real variable function with a finite waveform energy was a finite energy function while that with a finite waveform power was a finite power function. A noncorrelative white noise was defined as a real variable function in which an autocorrelation function took a specific value at a certain point; however, the autocorrelation function was different between the finite energy function and the finite power function. In other words, the definition of white noise was such that `an energy spectrum was a fixed value` in the finite energy function, and that `a power spectrum was a fixed value` in the finite power function. It was pointed out, by Matsuyama (1994) with the use of the energy spectrum conception, that the white noise belonging to the finite energy function took only the form of `an arbitrary impulse function that all turned to zero except a certain point`. The same conclusion was obtained with respect to the white noise belonging to the finite power function. 1 ref., 1 tab.
White noise excitation of road vehicle structures
Indian Academy of Sciences (India)
Road vehicle structures are modelled as mechanical systems ... in detail and recommendations for the choice of the design parameters are given. 2. ..... where q˙ζ denotes the noise intensity of ˙ζ(t) and δ(τ) is the Dirac distribution. Assuming.
Gaussian white noise as a resource for work extraction.
Dechant, Andreas; Baule, Adrian; Sasa, Shin-Ichi
2017-03-01
We show that uncorrelated Gaussian noise can drive a system out of equilibrium and can serve as a resource from which work can be extracted. We consider an overdamped particle in a periodic potential with an internal degree of freedom and a state-dependent friction, coupled to an equilibrium bath. Applying additional Gaussian white noise drives the system into a nonequilibrium steady state and causes a finite current if the potential is spatially asymmetric. The model thus operates as a Brownian ratchet, whose current we calculate explicitly in three complementary limits. Since the particle current is driven solely by additive Gaussian white noise, this shows that the latter can potentially perform work against an external load. By comparing the extracted power to the energy injection due to the noise, we discuss the efficiency of such a ratchet.
Entanglement probabilities of polymers: a white noise functional approach
International Nuclear Information System (INIS)
Bernido, Christopher C; Carpio-Bernido, M Victoria
2003-01-01
The entanglement probabilities for a highly flexible polymer to wind n times around a straight polymer are evaluated using white noise analysis. To introduce the white noise functional approach, the one-dimensional random walk problem is taken as an example. The polymer entanglement scenario, viewed as a random walk on a plane, is then treated and the entanglement probabilities are obtained for a magnetic flux confined along the straight polymer, and a case where an entangled polymer is subjected to the potential V = f-dot(s)θ. In the absence of the magnetic flux and the potential V, the entanglement probabilities reduce to a result obtained by Wiegel
Entanglement Swapping in the Presence of White and Color Noise
Dotsenko, Ivan S.; Korobka, R.
2018-02-01
The influence of white and color noise on the outcome of the entanglement swapping process is investigated in a four-qubit system. Critical degree of noise in initial state, that could destroy entanglement in a result state is presented. The entanglement characteristics, such as concurrence, tangle, etc. are compared. Results could be helpful for experiments regarding entanglement swapping as conditions for initial quantum entangled states, to obtain entangled result state.
External non-white noise and nonequilibrium phase transitions
International Nuclear Information System (INIS)
Sancho, J.M.; San Miguel, M.
1980-01-01
Langevin equations with external non-white noise are considered. A Fokker Planck equation valid in general in first order of the correlation time tau of the noise is derived. In some cases its validity can be extended to any value of tau. The effect of a finite tau in the nonequilibrium phase transitions induced by the noise is analyzed, by means of such Fokker Planck equation, in general, for the Verhulst equation under two different kind of fluctuations, and for a genetic model. It is shown that new transitions can appear and that the threshold value of the parameter can be changed. (orig.)
Chaotic dynamics of flexible beams driven by external white noise
Awrejcewicz, J.; Krysko, A. V.; Papkova, I. V.; Zakharov, V. M.; Erofeev, N. P.; Krylova, E. Yu.; Mrozowski, J.; Krysko, V. A.
2016-10-01
Mathematical models of continuous structural members (beams, plates and shells) subjected to an external additive white noise are studied. The structural members are considered as systems with infinite number of degrees of freedom. We show that in mechanical structural systems external noise can not only lead to quantitative changes in the system dynamics (that is obvious), but also cause the qualitative, and sometimes surprising changes in the vibration regimes. Furthermore, we show that scenarios of the transition from regular to chaotic regimes quantified by Fast Fourier Transform (FFT) can lead to erroneous conclusions, and a support of the wavelet analysis is needed. We have detected and illustrated the modifications of classical three scenarios of transition from regular vibrations to deterministic chaos. The carried out numerical experiment shows that the white noise lowers the threshold for transition into spatio-temporal chaotic dynamics. A transition into chaos via the proposed modified scenarios developed in this work is sensitive to small noise and significantly reduces occurrence of periodic vibrations. Increase of noise intensity yields decrease of the duration of the laminar signal range, i.e., time between two successive turbulent bursts decreases. Scenario of transition into chaos of the studied mechanical structures essentially depends on the control parameters, and it can be different in different zones of the constructed charts (control parameter planes). Furthermore, we found an interesting phenomenon, when increase of the noise intensity yields surprisingly the vibrational characteristics with a lack of noisy effect (chaos is destroyed by noise and windows of periodicity appear).
Auditory white noise reduces age-related fluctuations in balance.
Ross, J M; Will, O J; McGann, Z; Balasubramaniam, R
2016-09-06
Fall prevention technologies have the potential to improve the lives of older adults. Because of the multisensory nature of human balance control, sensory therapies, including some involving tactile and auditory noise, are being explored that might reduce increased balance variability due to typical age-related sensory declines. Auditory white noise has previously been shown to reduce postural sway variability in healthy young adults. In the present experiment, we examined this treatment in young adults and typically aging older adults. We measured postural sway of healthy young adults and adults over the age of 65 years during silence and auditory white noise, with and without vision. Our results show reduced postural sway variability in young and older adults with auditory noise, even in the absence of vision. We show that vision and noise can reduce sway variability for both feedback-based and exploratory balance processes. In addition, we show changes with auditory noise in nonlinear patterns of sway in older adults that reflect what is more typical of young adults, and these changes did not interfere with the typical random walk behavior of sway. Our results suggest that auditory noise might be valuable for therapeutic and rehabilitative purposes in older adults with typical age-related balance variability. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Monaural ICA of white noise mixtures is hard
DEFF Research Database (Denmark)
Hansen, Lars Kai; Petersen, Kaare Brandt
2003-01-01
Separation of monaural linear mixtures of `white' source signals is fundamentally ill-posed. In some situations it is not possible to find the mixing coefficients for the full `blind' problem. If the mixing coefficients are known, the structure of the source prior distribution determines the sour...... of white noise signals and give a set of `no go' cases.......Separation of monaural linear mixtures of `white' source signals is fundamentally ill-posed. In some situations it is not possible to find the mixing coefficients for the full `blind' problem. If the mixing coefficients are known, the structure of the source prior distribution determines the source...
The Feynman integrand as a white noise distribution beyond perturbation theory
International Nuclear Information System (INIS)
Grothaus, Martin; Vogel, Anna
2008-01-01
In this note the concepts of path integrals and techniques how to construct them are presented. Here we concentrate on a White Noise approach. Combining White Noise techniques with a generalized time-dependent Doss' formula Feynman integrands are constructed as white noise distributions beyond perturbation theory
Electric stimulation with sinusoids and white noise for neural prostheses
Directory of Open Access Journals (Sweden)
Daniel K Freeman
2010-02-01
Full Text Available We are investigating the use of novel stimulus waveforms in neural prostheses to determine whether they can provide more precise control over the temporal and spatial pattern of elicited activity as compared to conventional pulsatile stimulation. To study this, we measured the response of retinal ganglion cells to both sinusoidal and white noise waveforms. The use of cell-attached and whole cell patch clamp recordings allowed the responses to be observed without significant obstruction from the stimulus artifact. Electric stimulation with sinusoids elicited robust responses. White noise analysis was used to derive the linear kernel for the ganglion cell’s spiking response as well as for the underlying excitatory currents. These results suggest that in response to electric stimulation, presynaptic retinal neurons exhibit bandpass filtering characteristics with peak response that occur 25ms after onset. The experimental approach demonstrated here may be useful for studying the temporal response properties of other neurons in the CNS.
Signal-to-noise limitations in white light holography.
Ribak, E; Roddier, C; Roddier, F; Breckinridge, J B
1988-03-15
A simple derivation is given for the signal-to-noise ratio (SNR) in images reconstructed from incoherent holograms. Dependence is shown to be on the hologram SNR, object complexity, and the number of pixels in the detector. Reconstruction of involved objects becomes possible with high dynamic range detectors such as charge coupled devices. We have produced such white light holograms by means of a rotational shear interferometer combined with a chromatic corrector. A digital inverse transform recreated the object.
On the Danger of Detecting Network States in White Noise
Czech Academy of Sciences Publication Activity Database
Hlinka, Jaroslav; Hadrava, Michal
2015-01-01
Roč. 9, 12 February (2015), Article number 11 ISSN 1662-5188 R&D Projects: GA ČR GA13-23940S; GA ČR GA13-17187S Institutional support: RVO:67985807 Keywords : EEG * microstates * networks * dynamics * resting-state * nonstationary connectivity * stationarity * white noise Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 2.653, year: 2015
Identification of simulated microcalcifications in white noise and mammographic backgrounds
International Nuclear Information System (INIS)
Reiser, Ingrid; Nishikawa, Robert M.
2006-01-01
This work investigates human performance in discriminating between differently shaped simulated microcalcifications embedded in white noise or mammographic backgrounds. Human performance was determined through two alternative forced-choice (2-AFC) experiments. The signals used were computer-generated simple shapes that were designed such that they had equal signal energy. This assured equal detectability. For experiments involving mammographic backgrounds, signals were blurred to account for the imaging system modulation transfer function (MTF). White noise backgrounds were computer generated; anatomic background patches were extracted from normal mammograms. We compared human performance levels as a function of signal energy in the expected difference template. In the discrimination task, the expected difference template is the difference between the two signals shown. In white noise backgrounds, human performance in the discrimination task was degraded compared to the detection task. In mammographic backgrounds, human performance in the discrimination task exceeded that of the detection task. This indicates that human observers do not follow the optimum decision strategy of correlating the expected signal template with the image. Human observer performance was qualitatively reproduced by non-prewhitening with eye filter (NPWE) model observer calculations, in which spatial uncertainty was explicitly included by shifting the locations of the expected difference templates. The results indicate that human strategy in the discrimination task may be to match individual signal templates with the image individually, rather than to perform template matching between the expected difference template and the image
Listening to white noise counteracts visual and haptic pseudoneglect.
Cattaneo, Zaira; Lega, Carlotta; Vecchi, Tomaso; Vallar, Giuseppe
2012-01-01
Neurologically intact individuals usually show a leftward bias in line bisection, a tendency known as "pseudoneglect", likely reflecting a right-hemisphere dominance in controlling the allocation of spatial attention. Studies in brain-damaged patients with left visuospatial neglect have reported that auditory stimulation may reduce the deficit, both in a spatially dependent and in a spatially independent way. Here we show for the first time that the concurrent binaural presentation of auditory white noise affects healthy individuals' performance in both visual and haptic bisection, reducing their leftward error. We suggest that this effect depends on the noise boosting alertness and restoring the hemispheric activation balance. Our data clearly show that task-irrelevant auditory noise crossmodally affects the allocation of spatial resources in both the haptic and the visual space; future research may clarify whether these effects are specific for the type of auditory stimulation.
White noise excited non-ideal elasto-plastic oscillator
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Tarp-Johansen, Niels Jacob
1997-01-01
Two sets of 50 samples of the displacement response of the top traverse relative to the second traverse of an experimental shear frame with three traverses subject to white noise base shaking of two different intensities have been recorded at Institut fur Allgemeine Mechanik in 1995, and are in f......Two sets of 50 samples of the displacement response of the top traverse relative to the second traverse of an experimental shear frame with three traverses subject to white noise base shaking of two different intensities have been recorded at Institut fur Allgemeine Mechanik in 1995......, and are in file available for analysis. The column connection between the two top traverses were made of aluminum with a linear-elastic non-ideal plastic behavior, and the columns were therefore renewed after each experiment. The two other connections were made of steel with a purely linear-elastic behavior...... on an oscillator of more than one degree of freedom. Applied to the experimental frame the calculations give excellent predictions of the main distributional properties of the plastic displacement process....
Spatial pattern formation induced by Gaussian white noise.
Scarsoglio, Stefania; Laio, Francesco; D'Odorico, Paolo; Ridolfi, Luca
2011-02-01
The ability of Gaussian noise to induce ordered states in dynamical systems is here presented in an overview of the main stochastic mechanisms able to generate spatial patterns. These mechanisms involve: (i) a deterministic local dynamics term, accounting for the local rate of variation of the field variable, (ii) a noise component (additive or multiplicative) accounting for the unavoidable environmental disturbances, and (iii) a linear spatial coupling component, which provides spatial coherence and takes into account diffusion mechanisms. We investigate these dynamics using analytical tools, such as mean-field theory, linear stability analysis and structure function analysis, and use numerical simulations to confirm these analytical results. Copyright © 2010 Elsevier Inc. All rights reserved.
Effects of noise and parameter deviations in a bichromatic Raman white light cavity
International Nuclear Information System (INIS)
Sun Qingqing; Zubairy, M. Suhail; Shahriar, M. Selim
2010-01-01
We analyze the effects of noise and parameter deviations in a bichromatic Raman type white light cavity, with potential applications in precision measurements. The results show that the dispersion variation induced by parameter deviation can be controlled with an accuracy of 10 -4 . The laser phase noise decreases the dispersion magnitude while the amplitude noise increases it. Although we can always adjust the parameters to satisfy the white light condition, both types of noise make the cavity transmission curve uneven.
GHZ argument for four-qubit entangled states in the presence of white and colored noise
International Nuclear Information System (INIS)
Shi Mingjun; Ren Changliang; Chong Bo; Du Jiangfeng
2008-01-01
Greenberger-Horn-Zeilinger (GHZ) argument of nonlocality without inequalities is extended to the case of four-qubit mixed states. Three different kinds of entangled states are analyzed in presence of white and colored noise. The nonlocality properties of these states will be weakened and destroyed by the noise. We found that all these states have the same ability to resist the influence of white noise, while the cluster state is the most robust against colored noise
Shi, Pei-Ming; Li, Qun; Han, Dong-Ying
2017-06-01
This paper investigates a new asymmetric bistable model driven by correlated multiplicative colored noise and additive white noise. The mean first-passage time (MFPT) and the signal-to-noise ratio (SNR) as the indexes of evaluating the model are researched. Based on the two-state theory and the adiabatic approximation theory, the expressions of MFPT and SNR have been obtained for the asymmetric bistable system driven by a periodic signal, correlated multiplicative colored noise and additive noise. Simulation results show that it is easier to generate stochastic resonance (SR) to adjust the intensity of correlation strength λ. Meanwhile, the decrease of asymmetric coefficient r2 and the increase of noise intensity are beneficial to realize the transition between the two steady states in the system. At the same time, the twice SR phenomena can be observed by adjusting additive white noise and correlation strength. The influence of asymmetry of potential function on the MFPTs in two different directions is different.
Random walk in dynamically disordered chains: Poisson white noise disorder
International Nuclear Information System (INIS)
Hernandez-Garcia, E.; Pesquera, L.; Rodriguez, M.A.; San Miguel, M.
1989-01-01
Exact solutions are given for a variety of models of random walks in a chain with time-dependent disorder. Dynamic disorder is modeled by white Poisson noise. Models with site-independent (global) and site-dependent (local) disorder are considered. Results are described in terms of an affective random walk in a nondisordered medium. In the cases of global disorder the effective random walk contains multistep transitions, so that the continuous limit is not a diffusion process. In the cases of local disorder the effective process is equivalent to usual random walk in the absence of disorder but with slower diffusion. Difficulties associated with the continuous-limit representation of random walk in a disordered chain are discussed. In particular, the authors consider explicit cases in which taking the continuous limit and averaging over disorder sources do not commute
A simple white noise analysis of neuronal light responses.
Chichilnisky, E J
2001-05-01
A white noise technique is presented for estimating the response properties of spiking visual system neurons. The technique is simple, robust, efficient and well suited to simultaneous recordings from multiple neurons. It provides a complete and easily interpretable model of light responses even for neurons that display a common form of response nonlinearity that precludes classical linear systems analysis. A theoretical justification of the technique is presented that relies only on elementary linear algebra and statistics. Implementation is described with examples. The technique and the underlying model of neural responses are validated using recordings from retinal ganglion cells, and in principle are applicable to other neurons. Advantages and disadvantages of the technique relative to classical approaches are discussed.
Effects of White Noise on Off-Task Behavior and Academic Responding for Children with ADHD
Cook, Andrew; Bradley-Johnson, Sharon; Johnson, C. Merle
2014-01-01
We evaluated the effects of white noise played through headphones on off-task behavior, percentage of items completed, and percentage of items completed correctly for 3 students with attention deficit hyperactivity disorder (ADHD). Headphones plus white noise were associated with decreases in off-task behavior relative to baseline and…
AUDITORY NUCLEI: DISTINCTIVE RESPONSE PATTERNS TO WHITE NOISE AND TONES IN UNANESTHETIZED CATS.
GALIN, D
1964-10-09
Electrical responses to "white" noise and tonal stimuli were recorded from unanesthetized cats with permanently implanted bipolar electrodes. The cochlear nucleus, inferior colliculus, and medial geniculate each showed distinctive patterns of evoked activity. White noise and tones produced qualitatively different types of response. A decrease in activity characterized the response of the inferior colliculus to tonal stimuli.
The fractional coupled KdV equations: Exact solutions and white noise functional approach
International Nuclear Information System (INIS)
Ghany, Hossam A.; El Bab, A. S. Okb; Zabel, A. M.; Hyder, Abd-Allah
2013-01-01
Variable coefficients and Wick-type stochastic fractional coupled KdV equations are investigated. By using the modified fractional sub-equation method, Hermite transform, and white noise theory the exact travelling wave solutions and white noise functional solutions are obtained, including the generalized exponential, hyperbolic, and trigonometric types. (general)
Rausch, Vanessa H; Bauch, Eva M; Bunzeck, Nico
2014-07-01
In neural systems, information processing can be facilitated by adding an optimal level of white noise. Although this phenomenon, the so-called stochastic resonance, has traditionally been linked with perception, recent evidence indicates that white noise may also exert positive effects on cognitive functions, such as learning and memory. The underlying neural mechanisms, however, remain unclear. Here, on the basis of recent theories, we tested the hypothesis that auditory white noise, when presented during the encoding of scene images, enhances subsequent recognition memory performance and modulates activity within the dopaminergic midbrain (i.e., substantia nigra/ventral tegmental area, SN/VTA). Indeed, in a behavioral experiment, we can show in healthy humans that auditory white noise-but not control sounds, such as a sinus tone-slightly improves recognition memory. In an fMRI experiment, white noise selectively enhances stimulus-driven phasic activity in the SN/VTA and auditory cortex. Moreover, it induces stronger connectivity between SN/VTA and right STS, which, in addition, exhibited a positive correlation with subsequent memory improvement by white noise. Our results suggest that the beneficial effects of auditory white noise on learning depend on dopaminergic neuromodulation and enhanced connectivity between midbrain regions and the STS-a key player in attention modulation. Moreover, they indicate that white noise could be particularly useful to facilitate learning in conditions where changes of the mesolimbic system are causally related to memory deficits including healthy and pathological aging.
Kleijnen, J.P.C.
2006-01-01
Classic linear regression models and their concomitant statistical designs assume a univariate response and white noise.By definition, white noise is normally, independently, and identically distributed with zero mean.This survey tries to answer the following questions: (i) How realistic are these
Hyperbolic white noise functional solutions of Wick-type stochastic compound KdV-Burgers equations
International Nuclear Information System (INIS)
Han Xiu; Xie Yingchao
2009-01-01
Variable coefficient and Wick-type stochastic compound KdV-Burgers equations are investigated. By using white noise analysis, Hermite transform and the hyperbolic function method, we obtain a number of Wick versions of hyperbolic white noise functional solutions and hyperbolic function solutions for Wick-type stochastic and variable coefficient compound KdV-Burgers equations, respectively.
On low-frequency errors of uniformly modulated filtered white-noise models for ground motions
Safak, Erdal; Boore, David M.
1988-01-01
Low-frequency errors of a commonly used non-stationary stochastic model (uniformly modulated filtered white-noise model) for earthquake ground motions are investigated. It is shown both analytically and by numerical simulation that uniformly modulated filter white-noise-type models systematically overestimate the spectral response for periods longer than the effective duration of the earthquake, because of the built-in low-frequency errors in the model. The errors, which are significant for low-magnitude short-duration earthquakes, can be eliminated by using the filtered shot-noise-type models (i. e. white noise, modulated by the envelope first, and then filtered).
Adaptive Intelligent Ventilation Noise Control, Phase II
National Aeronautics and Space Administration — To address the NASA need for quiet on-orbit crew quarters (CQ), Physical Optics Corporation (POC) proposes to develop a new Adaptive Intelligent Ventilation Noise...
Audio-visual identification of place of articulation and voicing in white and babble noise.
Alm, Magnus; Behne, Dawn M; Wang, Yue; Eg, Ragnhild
2009-07-01
Research shows that noise and phonetic attributes influence the degree to which auditory and visual modalities are used in audio-visual speech perception (AVSP). Research has, however, mainly focused on white noise and single phonetic attributes, thus neglecting the more common babble noise and possible interactions between phonetic attributes. This study explores whether white and babble noise differentially influence AVSP and whether these differences depend on phonetic attributes. White and babble noise of 0 and -12 dB signal-to-noise ratio were added to congruent and incongruent audio-visual stop consonant-vowel stimuli. The audio (A) and video (V) of incongruent stimuli differed either in place of articulation (POA) or voicing. Responses from 15 young adults show that, compared to white noise, babble resulted in more audio responses for POA stimuli, and fewer for voicing stimuli. Voiced syllables received more audio responses than voiceless syllables. Results can be attributed to discrepancies in the acoustic spectra of both the noise and speech target. Voiced consonants may be more auditorily salient than voiceless consonants which are more spectrally similar to white noise. Visual cues contribute to identification of voicing, but only if the POA is visually salient and auditorily susceptible to the noise type.
The effects of background white noise on memory performance in inattentive school children
Directory of Open Access Journals (Sweden)
Sikström Sverker
2010-09-01
Full Text Available Abstract Background Noise is typically conceived of as being detrimental for cognitive performance; however, a recent computational model based on the concepts of stochastic resonance and dopamine related internal noise postulates that a moderate amount of auditive noise benefit individuals in hypodopaminergic states. On the basis of this model we predicted that inattentive children would be enhanced by adding background white noise while attentive children's performance would deteriorate. Methods Fifty-one secondary school pupils carried out an episodic verbal free recall test in two noise conditions. In the high noise condition, verb-noun sentences were presented during auditory background noise (white noise, 78 dB, and in the low noise condition sentences were presented without noise. Results Exposure to background noise improved performance for inattentive children and worsened performance for attentive children and eliminated episodic memory differences between attentive and inattentive school children. Conclusions Consistent with the model, our data show that cognitive performance can be moderated by external background white noise stimulation in a non-clinical group of inattentive participants. This finding needs replicating in a larger sample using more noise levels but if replicated has great practical applications by offering a non-invasive way to improve school results in children with attentional problems.
The effects of background white noise on memory performance in inattentive school children.
Söderlund, Göran B W; Sikström, Sverker; Loftesnes, Jan M; Sonuga-Barke, Edmund J
2010-09-29
Noise is typically conceived of as being detrimental for cognitive performance; however, a recent computational model based on the concepts of stochastic resonance and dopamine related internal noise postulates that a moderate amount of auditive noise benefit individuals in hypodopaminergic states. On the basis of this model we predicted that inattentive children would be enhanced by adding background white noise while attentive children's performance would deteriorate. Fifty-one secondary school pupils carried out an episodic verbal free recall test in two noise conditions. In the high noise condition, verb-noun sentences were presented during auditory background noise (white noise, 78 dB), and in the low noise condition sentences were presented without noise. Exposure to background noise improved performance for inattentive children and worsened performance for attentive children and eliminated episodic memory differences between attentive and inattentive school children. Consistent with the model, our data show that cognitive performance can be moderated by external background white noise stimulation in a non-clinical group of inattentive participants. This finding needs replicating in a larger sample using more noise levels but if replicated has great practical applications by offering a non-invasive way to improve school results in children with attentional problems.
Baijot, Simon; Slama, Hichem; Söderlund, Göran; Dan, Bernard; Deltenre, Paul; Colin, Cécile; Deconinck, Nicolas
2016-03-15
Optimal stimulation theory and moderate brain arousal (MBA) model hypothesize that extra-task stimulation (e.g. white noise) could improve cognitive functions of children with attention-deficit/hyperactivity disorder (ADHD). We investigate benefits of white noise on attention and inhibition in children with and without ADHD (7-12 years old), both at behavioral and at neurophysiological levels. Thirty children with and without ADHD performed a visual cued Go/Nogo task in two conditions (white noise or no-noise exposure), in which behavioral and P300 (mean amplitudes) data were analyzed. Spontaneous eye-blink rates were also recorded and participants went through neuropsychological assessment. Two separate analyses were conducted with each child separately assigned into two groups (1) ADHD or typically developing children (TDC), and (2) noise beneficiaries or non-beneficiaries according to the observed performance during the experiment. This latest categorization, based on a new index we called "Noise Benefits Index" (NBI), was proposed to determine a neuropsychological profile positively sensitive to noise. Noise exposure reduced omission rate in children with ADHD, who were no longer different from TDC. Eye-blink rate was higher in children with ADHD but was not modulated by white noise. NBI indicated a significant relationship between ADHD and noise benefit. Strong correlations were observed between noise benefit and neuropsychological weaknesses in vigilance and inhibition. Participants who benefited from noise had an increased Go P300 in the noise condition. The improvement of children with ADHD with white noise supports both optimal stimulation theory and MBA model. However, eye-blink rate results question the dopaminergic hypothesis in the latter. The NBI evidenced a profile positively sensitive to noise, related with ADHD, and associated with weaker cognitive control.
Investigating properties of white noise in the undergraduate laboratory
Energy Technology Data Exchange (ETDEWEB)
Hassan, Umer; Shamim, Sohaib; Anwar, M Sabieh [School of Science and Engineering, Lahore University of Management Sciences (LUMS), Opposite Sector U, D.H.A, Lahore 54792 (Pakistan)], E-mail: umersiddiqui@lums.edu.pk, E-mail: sohaibshamim@lums.edu.pk, E-mail: sabieh@lums.edu.pk
2009-09-15
This paper describes a simple noise circuit for the undergraduate physics laboratory. Students use this circuit to study the properties of electrical noise on a personal computer. This is made possible by using a data acquisition system that allows the experimenters to obtain large amounts of data on the computer, suitable for subsequent mathematical computations. Various properties such as mean, noise power, noise power density and the probability distribution of noise voltages are also explored.
The effects of background white noise on memory performance in inattentive school children
S?derlund, G?ran BW; Sikstr?m, Sverker; Loftesnes, Jan M; Sonuga-Barke, Edmund J
2010-01-01
Abstract Background Noise is typically conceived of as being detrimental for cognitive performance; however, a recent computational model based on the concepts of stochastic resonance and dopamine related internal noise postulates that a moderate amount of auditive noise benefit individuals in hypodopaminergic states. On the basis of this model we predicted that inattentive children would be enhanced by adding background white noise while attentive children's performance would deteriorate. Me...
Effects of white noise on event-related potentials in somatosensory Go/No-go paradigms.
Ohbayashi, Wakana; Kakigi, Ryusuke; Nakata, Hiroki
2017-09-06
Exposure to auditory white noise has been shown to facilitate human cognitive function. This phenomenon is termed stochastic resonance, and a moderate amount of auditory noise has been suggested to benefit individuals in hypodopaminergic states. The present study investigated the effects of white noise on the N140 and P300 components of event-related potentials in somatosensory Go/No-go paradigms. A Go or No-go stimulus was presented to the second or fifth digit of the left hand, respectively, at the same probability. Participants performed somatosensory Go/No-go paradigms while hearing three different white noise levels (45, 55, and 65 dB conditions). The peak amplitudes of Go-P300 and No-go-P300 in ERP waveforms were significantly larger under 55 dB than 45 and 65 dB conditions. White noise did not affect the peak latency of N140 or P300, or the peak amplitude of N140. Behavioral data for the reaction time, SD of reaction time, and error rates showed the absence of an effect by white noise. This is the first event-related potential study to show that exposure to auditory white noise at 55 dB enhanced the amplitude of P300 during Go/No-go paradigms, reflecting changes in the neural activation of response execution and inhibition processing.
Permutation entropy of finite-length white-noise time series.
Little, Douglas J; Kane, Deb M
2016-08-01
Permutation entropy (PE) is commonly used to discriminate complex structure from white noise in a time series. While the PE of white noise is well understood in the long time-series limit, analysis in the general case is currently lacking. Here the expectation value and variance of white-noise PE are derived as functions of the number of ordinal pattern trials, N, and the embedding dimension, D. It is demonstrated that the probability distribution of the white-noise PE converges to a χ^{2} distribution with D!-1 degrees of freedom as N becomes large. It is further demonstrated that the PE variance for an arbitrary time series can be estimated as the variance of a related metric, the Kullback-Leibler entropy (KLE), allowing the qualitative N≫D! condition to be recast as a quantitative estimate of the N required to achieve a desired PE calculation precision. Application of this theory to statistical inference is demonstrated in the case of an experimentally obtained noise series, where the probability of obtaining the observed PE value was calculated assuming a white-noise time series. Standard statistical inference can be used to draw conclusions whether the white-noise null hypothesis can be accepted or rejected. This methodology can be applied to other null hypotheses, such as discriminating whether two time series are generated from different complex system states.
[Auditory training with wide-band white noise: effects on the recruitment (III)].
Domínguez Ugidos, L J; Rodríguez Morejón, C; Vallés Varela, H; Iparraguirre Bolinaga, V; Knaster del Olmo, J
2001-05-01
The auditory training with wide-band white noise is a methodology for the qualitative recovery of the hearing loss in people suffering from sensorineural hearing loss. It is based on the application of a wide-band white modified noise. In a prospective study, we have assessed the modifications of the recruitment coefficient in a sample of 48 patients who have followed a program of 15 auditory training with wide-band white noise sessions. The average improvement of the recruitment coefficient expressed in percentage is a 7.7498%, which comes up to 23.5249% in the case of a binaural recruitment coefficient. From our results, it can be deduced that the auditory training with wide-band white noise reduces the recruitment. That is to say, the decrease of the recruitment in high intensities both binaurally and in all ears.
Wick calculus on spaces of generalized functions of compound poisson white noise
Lytvynov, Eugene W.; Rebenko, Alexei L.; Shchepan'ur, Gennadi V.
1997-04-01
We derive white noise calculus for a compound Poisson process. Namely, we consider, on the Schwartz space of tempered distributions, S', a measure of compound Poisson white noise, μcp, and construct a whole scale of standard nuclear triples ( Scp) - x ⊃ L2cp) ≡ L2( S', dμcp) ⊃( Scpx, x≥ 0, which are obtained as images under some isomorphism of the corresponding triples centred at a Fock space. It turns out that the most interesting case is x = 1, when our triple coincides with the triple that is constructed by using a system of Appell polynomials in the framework of non-Gaussian biorthogonal analysis. Our special attention is paid to the Wick calculus of the Poisson field, or the quantum compound Poisson white noise process in other terms, which is the family of operators acting from ( Scp) 1 into ( Scp) 1 as multiplication by the compound Poisson white noise ω( t).
The Effects of Hearing Aids on Localization of White Noise by Blind Subjects.
Bergen, Bruce R.
1980-01-01
An investigation was conducted to observe the effects of hearing aids on the ability of 20 blind veterans to localize white noise. In all cases, Ss performed more poorly on a localization task while wearing a hearing aid. (Author)
Impact of non-white noises in pulse amplitude measurements: a time-domain approach
International Nuclear Information System (INIS)
Pullia, A.
1998-01-01
The contribution of the 1/f-noise to the spectral line broadening in pulse amplitude measurements is derived with a time-domain analysis. The known time-domain relationships which provide the contributions of the series and parallel white noises are generalised for the case of 1/f and other typical non-white noises, by using the fractional derivative of either the system impulse response (time-invariant linear filters) or its weight function folded (time-variant linear filters). It is shown that a time-domain approach is also effective to determine the contribution of Lorentzian noises. A simple rule suitable to derive numerically the fractional derivative is given, which permits to calculate the effect of non-white noises even when the filter impulse response is not known analytically but only in sampled form. (orig.)
Baijot, Simon; Slama, Hichem; S?derlund, G?ran; Dan, Bernard; Deltenre, Paul; Colin, C?cile; Deconinck, Nicolas
2016-01-01
Background Optimal stimulation theory and moderate brain arousal (MBA) model hypothesize that extra-task stimulation (e.g. white noise) could improve cognitive functions of children with attention-deficit/hyperactivity disorder (ADHD). We investigate benefits of white noise on attention and inhibition in children with and without ADHD (7?12?years old), both at behavioral and at neurophysiological levels. Methods Thirty children with and without ADHD performed a visual cued Go/Nogo task in two...
Effect of White Noise on the Sleep of Elderly Patients Hospitalized in Coronary Care Units
Directory of Open Access Journals (Sweden)
Pouya Farokhnezhad Afshar
2016-04-01
Conclusion: Our results showed that white noise did not significantly change the sleep quality of old patients; however, it prevented the decrease in sleep duration and the increase in sleep latency duration. White noise with regard to its effects on increasing auditory stimulation threshold, its sleep induction, and suitable cost-effectiveness, can be used for some old patients hospitalized in CCUs.
Sezici, Emel; Yigit, Deniz
2018-02-01
This study aimed to compare the effects of swinging and playing of white noise on the crying and sleeping durations of colicky babies. Infantile colic (IC) is one of the most common reasons for doctor visits among babies younger than 3 months. One of five babies older than 3 months also experiences IC. IC, unlike gastrointestinal problems, is regarded as an individual differentiation and maturation of the central nervous system. Providing a warm bath, breastfeeding, swinging and playing of white noise are nonpharmacological methods. The efficiency of these methods has been proven by various studies independently of one another. The study is a prospective, multicentre, paired randomised controlled trial. The study was conducted between April-December 2016. The study sample consisted of 40 1-month-old babies with gas pains who passed a hearing screening and their mothers. The total daily crying and sleeping durations of the babies were determined without any intervention on the first week. On the second week, 20 randomly selected babies (first group) were swung each time they cried, and on the third week, they were made to listen to white noise. The other 20 babies (second group) were made to listen to white noise on the second week and were swung on the third week. Swinging and playing of white noise were performed until the babies stopped crying. After every intervention, the total crying and sleeping durations of the babies were evaluated using a "Colicky Baby's Diary." Playing of white noise significantly decreased the daily crying durations (p white noise was found to be a more effective nonpharmacological method on crying and sleeping durations of colicky babies than swinging. Playing of white noise may be helpful for parents and healthcare personnel in reducing the gas pains of babies. © 2017 John Wiley & Sons Ltd.
Auditory white noise reduces postural fluctuations even in the absence of vision.
Ross, Jessica Marie; Balasubramaniam, Ramesh
2015-08-01
The contributions of somatosensory, vestibular, and visual feedback to balance control are well documented, but the influence of auditory information, especially acoustic noise, on balance is less clear. Because somatosensory noise has been shown to reduce postural sway, we hypothesized that noise from the auditory modality might have a similar effect. Given that the nervous system uses noise to optimize signal transfer, adding mechanical or auditory noise should lead to increased feedback about sensory frames of reference used in balance control. In the present experiment, postural sway was analyzed in healthy young adults where they were presented with continuous white noise, in the presence and absence of visual information. Our results show reduced postural sway variability (as indexed by the body's center of pressure) in the presence of auditory noise, even when visual information was not present. Nonlinear time series analysis revealed that auditory noise has an additive effect, independent of vision, on postural stability. Further analysis revealed that auditory noise reduced postural sway variability in both low- and high-frequency regimes (> or noise. Our results support the idea that auditory white noise reduces postural sway, suggesting that auditory noise might be used for therapeutic and rehabilitation purposes in older individuals and those with balance disorders.
Effects of repeated exposure to white noise on central cholinergic activity in the rat.
Lai, H
1988-03-01
Acute (45 min) exposure to noise has been shown to decrease sodium-dependent high-affinity choline uptake activity in the frontal cortex and hippocampus of the rat. In the present experiment, the effects of repeated noise exposure on choline uptake in these two brain regions were studied. Rats were exposed to 100-dB white noise in ten 45-min sessions. Tolerance developed to the effects of noise on choline uptake. In addition, the effects were found to be classically conditionable to cues in the exposure environment. These data may have important implications in understanding the health hazard of noise exposure in both the public and occupational environments.
Synchronization of uncoupled excitable systems induced by white and coloured noise
International Nuclear Information System (INIS)
Zambrano, Samuel; Marino, Ines P; Seoane, Jesus M; Sanjuan, Miguel A F; Euzzor, Stefano; Geltrude, Andrea; Meucci, Riccardo; Arecchi, Fortunato T
2010-01-01
We study, both numerically and experimentally, the synchronization of uncoupled excitable systems due to a common noise. We consider two identical FitzHugh-Nagumo systems, which display both spiking and non-spiking behaviours in chaotic or periodic regimes. An electronic circuit provides a laboratory implementation of these dynamics. Synchronization is tested with both white and coloured noise, showing that coloured noise is more effective in inducing synchronization of the systems. We also study the effects on the synchronization of parameter mismatch and of the presence of intrinsic (not common) noise, and we conclude that the best performance of coloured noise is robust under these distortions.
Digital CDS for image sensors with dominant white and 1/f noise
International Nuclear Information System (INIS)
Stefanov, K.D.
2015-01-01
This paper investigates the performance of digital correlated double sampling (DCDS) for processing of image sensor signals in the presence of white and 1/f noise. The DCDS is compared with the dual slope integrator, which is the optimal analogue processing technique when only white noise is present. Based on the concept of matched filters, the paper derives and explores the optimal signal processing algorithms for signals with dominant 1/f noise, resulting in the highest achievable signal-to-noise ratio (SNR). Experimental results based on optimal DCDS on artificially generated 1/f noise signals are presented and discussed, together with the limitations of the method for more realistic sensor signals. It is shown that the noise level of the optimal DCDS can get close to the theoretical minimum
International Nuclear Information System (INIS)
Laude, Vincent
2002-01-01
The problem of noise analysis in measuring the group delay introduced by a dispersive optical element by use of white-light interferometric cross correlation is investigated. Two noise types, detection noise and position noise, are specifically analyzed. Detection noise is shown to be highly sensitive to the spectral content of the white-light source at the frequency considered and to the temporal acquisition window. Position noise, which arises from the finite accuracy of the measurement of the scanning mirror's position, can severely damage the estimation of the group delay. Such is shown to be the case for fast Fourier transform-based estimation algorithms. A new algorithm that is insensitive to scanning delay errors is proposed, and subfemtosecond accuracy is obtained without any postprocessing
White matter abnormalities of microstructure and physiological noise in schizophrenia
Cheng, Hu; Newman, Sharlene D.; Kent, Jerillyn S.; Bolbecker, Amanda; Klaunig, Mallory J.; O'Donnell, Brian F.; Puce, Aina; Hetrick, William P.
2015-01-01
White matter abnormalities in schizophrenia have been revealed by many imaging techniques and analysis methods. One of the findings by diffusion tensor imaging is a decrease in fractional anisotropy (FA), which is an indicator of white matter integrity. On the other hand, elevation of metabolic rate in white matter was observed from positron emission tomography (PET) studies. In this report, we aim to compare the two structural and functional effects on the same subjects. Our comparison is ba...
Estimation of Spectral Exponent Parameter of 1/f Process in Additive White Background Noise
Directory of Open Access Journals (Sweden)
Semih Ergintav
2007-01-01
Full Text Available An extension to the wavelet-based method for the estimation of the spectral exponent, γ, in a 1/fγ process and in the presence of additive white noise is proposed. The approach is based on eliminating the effect of white noise by a simple difference operation constructed on the wavelet spectrum. The γ parameter is estimated as the slope of a linear function. It is shown by simulations that the proposed method gives reliable results. Global positioning system (GPS time-series noise is analyzed and the results provide experimental verification of the proposed method.
Effects of white noise and holding on pain perception in newborns.
Karakoç, Ayse; Türker, Funda
2014-12-01
This experimental study on newborns was conducted to compare the effects of various atraumatic care procedures during an infant's crying response to pain. Included in this study were 120 newborns chosen from among healthy infants admitted to the Obstetrics Department of Çanakkale State Hospital between April 2010 and June 2010. The patients were divided into three physically homogeneous groups. Infants in group 1 were held on the mothers' laps, infants in group 2 were held on the mother's laps and listened to white noise, and infants in group 3 lay in their cribs and listened to white noise while undergoing a painful procedure. Data collection included the Neonatal Infant Pain Scale, which was used to evaluate the behavioral responses to pain during a heel prick blood draw and a newborn information sheet developed by the researcher. Changes in cardiac and respiratory rates recorded during the invasive procedure were statistically significant among the three groups (p white noise. This group was then followed by the infants who listened to white noise while being held by their mothers. The highest behavioral reaction was reported by those infants who were held by their mothers but did not listen to white noise. According to the results, white noise is an effective nonpharmacologic method to control pain, reduce crying time, and positively effect vital signs. Therefore, it is recommended that the use of white noise be practiced on newborns when they undergo painful procedures. Copyright © 2014 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights reserved.
Piribedil affects dopamine turnover in cochleas stimulated by white noise.
Gil-Loyzaga, P; Vicente-Torres, M A; Fernández-Mateos, P; Arce, A; Esquifino, A
1994-09-01
The presence of dopamine (DA) within the cochlea has been previously reported, indicating that its turnover increases under noise stimulation. In the present report, piribedil, a dopaminergic D2 agonist, was used in order to provide evidence of the activity of D2 receptors in the turnover of DA under noise stimulation. Long-Evans rats were intraperitoneally injected with distilled water or with a solution of piribedil one hour previously to either noise or silence exposure. Noise stimulation was performed in an anechoic chamber at 70, 90 or 110 dB SPL for one hour. The animals were then sacrificed and the cochlear contents of DA and its metabolites dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were quantified by HPLC with electrochemical detection. The administration of piribedil to animals kept in silence did not modify the cochlear DA, DOPAC and HVA content. Noise stimulation resulted in a decrease of the cochlear DA content and an increase of the cochlear DOPAC and HVA contents in vehicle treated animals. The administration of piribedil resulted in a blockade of this noise induced cochlear DA turnover. These results suggest that piribedil stimulates cochlear D2 receptors controlling the cochlear DA release. Piribedil action on D2 receptors could explain the improvement observed in some cochleo-vestibular diseases signs after piribedil treatment.
Dynamical response of the Ising model to the time dependent magnetic field with white noise
Akıncı, Ümit
2018-03-01
The effect of the white noise in time dependent magnetic field on the dynamic behavior of the Ising model has been investigated within the effective field theory based on Glauber type of stochastic process. Discrete white noise has been chosen from both Gaussian and uniform probability distributions. Detailed investigation on probability distribution of dynamical order parameter results that, both type of noise distributions yield the same probability distribution related to the dynamical order parameter, namely Gaussian probability distribution. The variation of the parameters that describe the probability distribution of dynamical order parameter (mean value and standard deviation) with temperature and strength of the noise have been inspected. Also, it has been shown that, rising strength of the noise can induce dynamical phase transition in the system.
Noise propagation issues in Belle II pixel detector power cable
Iglesias, M.; Arteche, F.; Echeverria, I.; Pradas, A.; Rivetta, C.; Moser, H.-G.; Kiesling, C.; Rummel, S.; Arcega, F. J.
2018-04-01
The vertex detector used in the upgrade of High-Energy physics experiment Belle II includes DEPFET pixel detector (PXD) technology. In this complex topology the power supply units and the front-end electronics are connected through a PXD power cable bundle which may propagate the output noise from the power supplies to the vertex area. This paper presents a study of the propagation of noise caused by power converters in the PXD cable bundle based on Multi-conductor Transmission Line (MTL) theory. The work exposes the effect of the complex cable topology and shield connections on the noise propagation, which has an impact on the requirements of the power supplies. This analysis is part of the electromagnetic compatibility based design focused on functional safety to define the shield connections and power supply specifications required to ensure the successful integration of the detector and, specifically, to achieve the designed performance of the front-end electronics.
Correlated and uncorrelated invisible temporal white noise alters mesopic rod signaling.
Hathibelagal, Amithavikram R; Feigl, Beatrix; Kremers, Jan; Zele, Andrew J
2016-03-01
We determined how rod signaling at mesopic light levels is altered by extrinsic temporal white noise that is correlated or uncorrelated with the activity of one (magnocellular, parvocellular, or koniocellular) postreceptoral pathway. Rod and cone photoreceptor excitations were independently controlled using a four-primary photostimulator. Psychometric (Weibull) functions were measured for incremental rod pulses (50 to 250 ms) in the presence (or absence; control) of perceptually invisible subthreshold extrinsic noise. Uncorrelated (rod) noise facilitates rod detection. Correlated postreceptoral pathway noise produces differential changes in rod detection thresholds and decreases the slope of the psychometric functions. We demonstrate that invisible extrinsic noise changes rod-signaling characteristics within the three retinogeniculate pathways at mesopic illumination depending on the temporal profile of the rod stimulus and the extrinsic noise type.
International Nuclear Information System (INIS)
Grigoriu, Mircea; Samorodnitsky, Gennady
2004-01-01
Two methods are considered for assessing the asymptotic stability of the trivial solution of linear stochastic differential equations driven by Poisson white noise, interpreted as the formal derivative of a compound Poisson process. The first method attempts to extend a result for diffusion processes satisfying linear stochastic differential equations to the case of linear equations with Poisson white noise. The developments for the method are based on Ito's formula for semimartingales and Lyapunov exponents. The second method is based on a geometric ergodic theorem for Markov chains providing a criterion for the asymptotic stability of the solution of linear stochastic differential equations with Poisson white noise. Two examples are presented to illustrate the use and evaluate the potential of the two methods. The examples demonstrate limitations of the first method and the generality of the second method
Effects of music and white noise on working memory performance in monkeys.
Carlson, S; Rämä, P; Artchakov, D; Linnankoski, I
1997-09-08
It has been suggested that Mozart's music may have beneficial effects on the performance of cognitive tasks in humans. In the present study the effects of Mozart's piano music, white noise, simple rhythm and silence were studied on the performance of a delayed response (DR) task in monkeys. The acoustic treatments were given for 15 min, either before or during DR testing. The acoustic treatments did not affect DR performance when given before testing. However, Mozart's piano music played during DR testing caused a significant deterioration in the performance of the monkeys, whereas white noise improved it. It is suggested that Mozart's music serves as distractive stimulation during DR performance thus affecting working-memory-related neuronal processing and performance. White background noise, on the other hand, may improve DR performance by protecting against environmental distraction during testing.
Stationary response of multi-degree-of-freedom vibro-impact systems to Poisson white noises
International Nuclear Information System (INIS)
Wu, Y.; Zhu, W.Q.
2008-01-01
The stationary response of multi-degree-of-freedom (MDOF) vibro-impact (VI) systems to random pulse trains is studied. The system is formulated as a stochastically excited and dissipated Hamiltonian system. The constraints are modeled as non-linear springs according to the Hertz contact law. The random pulse trains are modeled as Poisson white noises. The approximate stationary probability density function (PDF) for the response of MDOF dissipated Hamiltonian systems to Poisson white noises is obtained by solving the fourth-order generalized Fokker-Planck-Kolmogorov (FPK) equation using perturbation approach. As examples, two-degree-of-freedom (2DOF) VI systems under external and parametric Poisson white noise excitations, respectively, are investigated. The validity of the proposed approach is confirmed by using the results obtained from Monte Carlo simulation. It is shown that the non-Gaussian behaviour depends on the product of the mean arrival rate of the impulses and the relaxation time of the oscillator
International Nuclear Information System (INIS)
Suryawan, Herry P.; Gunarso, Boby
2017-01-01
The generalized mixed fractional Brownian motion is defined by taking linear combinations of a finite number of independent fractional Brownian motions with different Hurst parameters. It is a Gaussian process with stationary increments, posseses self-similarity property, and, in general, is neither a Markov process nor a martingale. In this paper we study the generalized mixed fractional Brownian motion within white noise analysis framework. As a main result, we prove that for any spatial dimension and for arbitrary Hurst parameter the self-intersection local times of the generalized mixed fractional Brownian motions, after a suitable renormalization, are well-defined as Hida white noise distributions. The chaos expansions of the self-intersection local times in the terms of Wick powers of white noises are also presented. (paper)
Effect of White Noise in Relieving Vaccination Pain in Premature Infants.
Kucukoglu, Sibel; Aytekin, Aynur; Celebioglu, Ayda; Celebi, Arzu; Caner, Ibrahim; Maden, Rukiye
2016-12-01
The purpose of this study was to evaluate the effect of white noise as a distraction method in relieving procedural pain caused by vaccination for premature infants. This experimental study was performed at a neonatal intensive care unit (NICU) of a university hospital in Turkey between July and September 2013. The study population was composed of 75 premature infants (35 in the study group and 40 in the control group) who met the inclusion criteria. Premature infants in the study group were exposed to white noise using MP3 players placed at the head of the infants' open crib for 1 minute before vaccination. The white noise continued until 1 minute after vaccination. Premature infants in the control group were not exposed to white noise. The Premature Infant Information Form, Intervention Follow-up Form, and Premature Infant Pain Profile (PIPP) were used to collect study data. Descriptive statistics, chi-square test, and independent sample t-tests were used to evaluate the data. The pain level of the control group (PIPP = 14.35 ± 2.59) was significantly higher than the pain level of the study group (PIPP = 8.14 ± 3.14) (p White noise was found to be effective for this sample; however, there is a dire need for extensive research on white noise and its use with this vulnerable population. Copyright © 2016 American Society for Pain Management Nursing. Published by Elsevier Inc. All rights reserved.
Suppression of Growth by Multiplicative White Noise in a Parametric Resonant System
Ishihara, Masamichi
2015-02-01
The growth of the amplitude in a Mathieu-like equation with multiplicative white noise is studied. To obtain an approximate analytical expression for the exponent at the extremum on parametric resonance regions, a time-interval width is introduced. To determine the exponents numerically, the stochastic differential equations are solved by a symplectic numerical method. The Mathieu-like equation contains a parameter α determined by the intensity of noise and the strength of the coupling between the variable and noise; without loss of generality, only non-negative α can be considered. The exponent is shown to decrease with α, reach a minimum and increase after that. The minimum exponent is obtained analytically and numerically. As a function of α, the minimum at α≠0, occurs on the parametric resonance regions of α=0. This minimum indicates suppression of growth by multiplicative white noise.
Gaussian white noise excited elasto-Plastic oscillator of several degrees of freedom
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Randrup-thomsen, Søren
1996-01-01
this restriction the obtained Slepian model results fit well with the results obtained by direct response simulations. Also it is observed that the restriction gets less importance for decreasing intensity of the white noise excitation. Keywords: Random vibrations, Slepian models, MDOF elasto-plastic oscillator......The Slepian model process method has turned out to be a powerful tool to obtain accurate approximations to the long run probability distributions of the plastic displacements of a one degree of freedom linear elastic-ideal plastic oscillator (EPO) subject to stationary Gaussian white noise...
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov; Ditlevsen, Ove Dalager
2003-01-01
The object of study is a stationary Gaussian white noise excited MDOF linear elastic, ideal plastic, linearly damped, statically determinate oscillator with several potential elements of ideal plastic yielding. Specifically the study is exemplified for a plane multistory shear frame with rigid...... traverses where all the connecting columns except the columns in one or more of the bottom floors have finite symmetrical yield limits. The white noise excitation acts on the mass of the first floor making the movement of the elastic bottom floors simulate a ground motion that interacts with the structure...
Analysis of white noise excited elasto-plastic oscillator of several degrees of freedom
DEFF Research Database (Denmark)
Randrup-Thomsen, Søren
1997-01-01
The response of the white noise excited multi-degree-of-freedom (MDOF) oscillator has been analyzed in order to describe the plastic displacements of the relative response. Three different types of structural systems have been considered. The first type is a shear-wall frame having elastic......-ideal plastic stiffness properties of the columns connecting the two top-most floors. The second type is a shear-wall frame having elastic-ideal plastic stiffness properties of all columns, while the third type is a single-degree-of-freedom (SDOF) oscillator excited by horizontal and vertical white noise ground...
A random-parametric reactor model with direct feedback and non-white noise
International Nuclear Information System (INIS)
Sako, O.; Taniguchi, A.; Kuroda, Y.
1982-01-01
The effects of multiplicative direct power feedback and non-white reactivity noise on the fluctuations of the neutron density are studied, based on the master equation using the cumulant expansion and the system-size expansion. The results obtained are the following: non-whiteness of reactivity noise reduces the variance of neutron density, as well as the level of the power spectral density. The nonlinear effect of power feedback gives rise to at least a pair of corner frequencies, in contrast to the single corner frequency in linearized case. (author)
Zieliński, K
1981-01-01
The course of differentiation learning, using the conditioned emotional response (CER) method, was investigated in two groups of 16 rats. The discriminative stimuli consisted of decreases in the 80 dB background white noise to either 70 dB or 60 dB. Differentiation learning was more efficient with the larger decrease of background noise intensity as the CS(+) and the smaller decrease as the CS(-) than vice versa.
Signal-to-noise limitations in white light holography
Ribak, Erez; Breckinridge, James B.; Roddier, Claude; Roddier, Francois
1988-01-01
A simple derivation is given for the SNR in images reconstructed from incoherent holograms. Dependence is shown to be on the hologram SNR, object complexity, and the number of pixels in the detector. Reconstruction of involved objects becomes possible with high-dynamic-range detectors such as CCDs. White-light holograms have been produced by means of a rotational shear interferometer combined with a chromatic corrector. A digital inverse transform recreated the object.
Ilkkaya, Nazan Koylu; Ustun, Faik Emre; Sener, Elif Bengi; Kaya, Cengiz; Ustun, Yasemin Burcu; Koksal, Ersin; Kocamanoglu, Ismail Serhat; Ozkan, Fatih
2014-10-01
To compare effects of music, white noise, and ambient (background) noise on patient anxiety and sedation. Open, parallel, and randomized controlled trial. Seventy-five patients aged 18 to 60 years who were scheduled for surgical procedures under spinal anesthesia were randomly assigned to ambient noise (Group O), white noise (Group B), or music groups (Group M). We evaluated patients' anxiety and sedation levels via the Observer's Assessment of Alertness/Sedation (OAA/S) scale and the State-Trait Anxiety Inventory (STAI) questionnaire. At 5 minutes before surgery, the STAI-State Anxiety Inventory (SA) value was significantly lower in Group M than the other groups. At 30-minute recovery, Group M showed significantly lower STAI-SA values than the other groups. Patient satisfaction was highest in Group M. OAA/S values were not significantly different between groups during any period (P > .05). We suggest that patient-selected music reduces perioperative anxiety and contributes to patient satisfaction during the perioperative period. Copyright © 2014 American Society of PeriAnesthesia Nurses. Published by Elsevier Inc. All rights reserved.
Non-white noise in fMRI: Does modelling have an impact?
DEFF Research Database (Denmark)
Lund, Torben Ellegaard; Madsen, Kristoffer Hougaard; Sidaros, Karam
2006-01-01
are typically modelled as an autoregressive (AR) process. In this paper, we propose an alternative approach: Nuisance Variable Regression (NVR). By inclusion of confounding effects in a general linear model (GLM), we first confirm that the spatial distribution of the various fMRI noise sources is similar......The sources of non-white noise in Blood Oxygenation Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) are many. Familiar sources include low-frequency drift due to hardware imperfections, oscillatory noise due to respiration and cardiac pulsation and residual movement artefacts...
A One-Dimensional Wave Equation with White Noise Boundary Condition
International Nuclear Information System (INIS)
Kim, Jong Uhn
2006-01-01
We discuss the Cauchy problem for a one-dimensional wave equation with white noise boundary condition. We also establish the existence of an invariant measure when the noise is additive. Similar problems for parabolic equations were discussed by several authors. To our knowledge, there is only one work which investigated the initial-boundary value problem for a wave equation with random noise at the boundary. We handle a more general case by a different method. Our result on the existence of an invariant measure relies on the author's recent work on a certain class of stochastic evolution equations
Speech Denoising in White Noise Based on Signal Subspace Low-rank Plus Sparse Decomposition
Directory of Open Access Journals (Sweden)
yuan Shuai
2017-01-01
Full Text Available In this paper, a new subspace speech enhancement method using low-rank and sparse decomposition is presented. In the proposed method, we firstly structure the corrupted data as a Toeplitz matrix and estimate its effective rank for the underlying human speech signal. Then the low-rank and sparse decomposition is performed with the guidance of speech rank value to remove the noise. Extensive experiments have been carried out in white Gaussian noise condition, and experimental results show the proposed method performs better than conventional speech enhancement methods, in terms of yielding less residual noise and lower speech distortion.
International Nuclear Information System (INIS)
Pal, Suvajit; Sinha, Sudarson Sekhar; Ganguly, Jayanta; Ghosh, Manas
2013-01-01
Highlights: • The excitation kinetics of impurity doped quantum dot has been investigated. • The dot is subject to Gaussian white noise. • External oscillatory field is also applied. • Noise strength and field intensity fabricate the kinetics. • Role of dopant location has also been analyzed. - Abstract: We investigate the excitation kinetics of a repulsive impurity doped quantum dot initiated by simultaneous application of Gaussian white noise and external sinusoidal field. We have considered both additive and multiplicative noise (in Stratonovich sense). The combined influences of noise strength (ζ) and the field intensity (∊) have been capsuled by invoking their ratio (η). The said ratio and the dopant location have been found to fabricate the kinetics in a delicate way. Moreover, the influences of additive and multiplicative nature of the noise on the excitation kinetics have been observed to be widely different. The investigation reveals emergence of maximization/minimization and saturation in the excitation kinetics as a result of complex interplay between η and the dopant coordinate (r 0 ). The present investigation is believed to provide some useful insights in the functioning of mesoscopic devices where noise plays some significant role
International Nuclear Information System (INIS)
Ganguly, Jayanta; Ghosh, Manas
2014-01-01
Highlights: • Linear polarizability of quantum dot has been studied. • Quantum dot is doped with a repulsive impurity. • The polarizabilities are frequency-dependent. • Influence of Gaussian white noise has been monitored. • Noise exploited is of additive and multiplicative nature. - Abstract: We investigate the profiles of diagonal components of frequency-dependent linear (α xx and α yy ) optical response of repulsive impurity doped quantum dots. The dopant impurity potential chosen assumes Gaussian form. The study principally puts emphasis on investigating the role of noise on the polarizability components. In view of this we have exploited Gaussian white noise containing additive and multiplicative characteristics (in Stratonovich sense). The frequency-dependent polarizabilities are studied by exposing the doped dot to a periodically oscillating external electric field of given intensity. The oscillation frequency, confinement potentials, dopant location, and above all, the noise characteristics tune the linear polarizability components in a subtle manner. Whereas the additive noise fails to have any impact on the polarizabilities, the multiplicative noise influences them delicately and gives rise to additional interesting features
FACTORS AFFECTING ROAD TRAFFIC NOISE ANNOYANCE AMONG WHITE-COLLAR EMPLOYEES WORKING IN TEHRAN
Directory of Open Access Journals (Sweden)
*1I. Alimohammadi, 2P. Nassiri, 3M. Azkhosh, 4M. Hoseini
2010-01-01
Full Text Available The effect of personal and attitudinal factors, noise level, hearing status and psychological traits on traffic-related noise annoyance among white-collar employees working in Tehran has been carefully analyzed. This survey has been conducted by interviewing 495 citizens working in non-manufacturing industries in Tehran, using questionnaires, Weinstein noise sensitivity scale, Beck’s depression, Buss and perry’s aggression, Zung’s anxiety, job satisfaction and Eysenc’s personality inventory. These citizens were office workers or store employees. Noise annoyance was determined both by numerical-based questionnaire criterion and by verbal index. Personal information, attitudinal factors and hearing conditions were determined using a general questionnaire. The amount of workplace noise the participants were exposed to was directly measured at their workplaces. It was revealed that among personal factors, age (p=0.030, marital status (p=0.004, residential period (p=0.001 and wealth (p=0.04 were related to noise annoyance. Attitudinal factors including sensitivity to noise (p=0.001, individual’s opinion on the need to control the noise (p=0.000 and individuals’ assessment of the amount of the workplace ambient noise (p= 0.000 were found to have relationship with noise annoyance. No meaningful relationship was seen between the equivalent noise level (p=0.879 and statistical noise level of L90 (p=0.909. The present study revealed that among all effective factors involved in noise annoyance, attitudinal factors had the most significant role in this regard.
Evoked response of heart rate variability using short-duration white noise.
Lee, Guo-She; Chen, Mei-Ling; Wang, Gin-You
2010-06-24
To investigate and to establish a model for evaluation of the instant cardiovascular responses to the noises of low-to-moderate intensity, sixteen healthy subjects were enrolled. The white noises were binaurally presented with a supra-aural earphone. The test intensities of noises were no noise, 50, 60, 70 and 80 dBA. Each noise was continued for 5 min and the electrocardiogram was simultaneously recorded. The cardiac autonomic responses were evaluated using power spectral analysis of the R-R contour obtained from digital signal processing of the ECG tracings. The result showed that the mean heart rate and mean blood pressure did not change significantly with the noises. However, the low-frequency power (LF) which represents cardiac autonomic modulations and the ratio (LHR) of LF to high-frequency power (HF) which reflects cardiac sympathetic modulations were significantly greater in the noise intensity of 50, 60, 70 and 80dBA (pnoise intensity (rho=0.90, pwhite noises can be detected using power spectral analysis of heart rate variability and the evoked responses may provide a sensitive way to evaluate the instant effect of noise to humans.
A note of spaces of test and generalized functions of Poisson white noise
Lytvynov, E.
2006-01-01
The paper is devoted to construction and investigation of some riggings of the $L^2$-space of Poisson white noise. A particular attention is paid to the existence of a continuous version of a function from a test space, and to the property of an algebraic structure under pointwise multiplication of functions from a test space.
Limit theorems for power variations of ambit fields driven by white noise
DEFF Research Database (Denmark)
Pakkanen, Mikko
We study the asymptotic behavior of lattice power variations of two-parameter ambit fields that are driven by white noise. Our first result is a law of large numbers for such power variations. Under a constraint on the memory of the ambit field, normalized power variations are shown to converge...
Continuous White Noise to Reduce Resistance Going to Sleep and Night Wakings in Toddlers
Forquer, LeAnne M.; Johnson, C. Merle
2005-01-01
White noise generators were turned on at 75 dB at bedtime and kept on all night to treat resistance going to sleep and night wakings in one-year-old toddlers. In a multiple baseline design four sets of parents recorded duration of resistance going to sleep, number of night wakings, completed surveys of their child's feeding and sleeping patterns…
Partial sums of lagged cross-products of AR residuals and a test for white noise
de Gooijer, J.G.
2008-01-01
Partial sums of lagged cross-products of AR residuals are defined. By studying the sample paths of these statistics, changes in residual dependence can be detected that might be missed by statistics using only the total sum of cross-products. Also, a test statistic for white noise is proposed. It is
Limit theorems for power variations of ambit field driven by white noise
DEFF Research Database (Denmark)
Pakkanen, Mikko S.
2014-01-01
We study the asymptotics of lattice power variations of two-parameter ambit fields driven by white noise. Our first result is a law of large numbers for power variations. Under a constraint on the memory of the ambit field, normalized power variations converge to certain integral functionals...
Pries, Lotta-Katrin; Guloksuz, Sinan; Menne-Lothmann, Claudia; Decoster, Jeroen; van Winkel, Ruud; Collip, Dina; Delespaul, Philippe; De Hert, Marc; Derom, Catherine; Thiery, Evert; Jacobs, Nele; Wichers, Marieke; Simons, Claudia J. P.; Rutten, Bart P. F.; van Os, Jim
2017-01-01
Background: An association between white noise speech illusion and psychotic symptoms has been reported in patients and their relatives. This supports the theory that bottom-up and top-down perceptual processes are involved in the mechanisms underlying perceptual abnormalities. However, findings in
White Noise Responsiveness of an AlN Piezoelectric MEMS Cantilever Vibration Energy Harvester
International Nuclear Information System (INIS)
Jia, Y; Seshia, A A
2014-01-01
This paper reports the design, analysis and experimental characterisation of a piezoelectric MEMS cantilever vibration energy harvester, the enhancement of its power output by adding various values of end mass, as well as assessing the responsiveness towards white noise. Devices are fabricated using a 0.5 μm AlN on 10 μm doped Si process. Cantilevers with 5 mm length and 2 mm width were tested at either unloaded condition (MC0: f n 577 Hz) or subjected to estimated end masses of 2 mg (MC2: f n 129 Hz) and 5 mg (MC5: f n 80 Hz). While MC0 was able to tolerate a higher drive acceleration prior to saturation (7 g with 0.7 μW), MC5 exhibited higher peak power attainable at a lower input vibration (2.56 μW at 3 ms −2 ). MC5 was also subjected to band-limited (10 Hz to 2 kHz) white noise vibration, where the power response was only a fraction of its resonant counterpart for the same input: peak instantaneous power >1 μW was only attainable beyond 2 g of white noise, whereas single frequency resonant response only required 2.5 ms −2 . Both the first resonant response and the band-limited white noise response were also compared to a numerical model, showing close agreements
Spectral density of oscillator with bilinear stiffness and white noise excitation
DEFF Research Database (Denmark)
Rüdinger, Finn; Krenk, Steen
2003-01-01
The power spectral density of an oscillator with bilinear stiffness excited by Gaussian white noise is considered. A method originally proposed by Krenk and Roberts [J Appl Mech 66 (1999) 225] relying on slowly changing energy for lightly damped systems is applied. In this method an approximate...
Variable Perception of White Noise in Ambiguous Phonetic Contexts: The Case of /p/ and /f/
Shafiro, Valeriy; Raphael, Lawrence J.
2007-01-01
The roles of spectro-temporal coherence, lexical status, and word position in the perception of speech in acoustic signals containing a mixture of speech and nonspeech sounds were investigated. Stimuli consisted of nine (non)words in which either white noise was inserted only into the silent interval preceding and/or following the onset of vocalic…
International Nuclear Information System (INIS)
Ji, Un Cig; Obata, Nobuaki
2010-01-01
The implementation problem for the canonical commutation relation is reduced to a system of differential equations for Fock space operators containing new type of derivatives. We solve these differential equations systematically by means of quantum white noise calculus, and obtain the solution to the implementation problem.
Effects of white noise on Callsign Acquisition Test and Modified Rhyme Test scores.
Blue-Terry, Misty; Letowski, Tomasz
2011-02-01
The Callsign Acquisition Test (CAT) is a speech intelligibility test developed by the US Army Research Laboratory. The test has been used to evaluate speech transmission through various communication systems but has not been yet sufficiently standardised and validated. The aim of this study was to compare CAT and Modified Rhyme Test (MRT) performance in the presence of white noise across a range of signal-to-noise ratios (SNRs). A group of 16 normal-hearing listeners participated in the study. The speech items were presented at 65 dB(A) in the background of white noise at SNRs of -18, -15, -12, -9 and -6 dB. The results showed a strong positive association (75.14%) between the two tests, but significant differences between the CAT and MRT absolute scores in the range of investigated SNRs. Based on the data, a function to predict CAT scores based on existing MRT scores and vice versa was formulated. STATEMENT OF RELEVANCE: This work compares performance data of a common speech intelligibility test (MRT) with a new test (CAT) in the presence of white noise. The results here can be used as a part of the standardisation procedures and provide insights to the predictive capabilities of the CAT to quantify speech intelligibility communication in high-noise military environments.
Pries, Lotta-Katrin; Guloksuz, Sinan; Menne-Lothmann, Claudia; Decoster, Jeroen; van Winkel, Ruud; Collip, Dina; Delespaul, Philippe; De Hert, Marc; Derom, Catherine; Thiery, Evert; Jacobs, Nele; Wichers, Marieke; Simons, Claudia J P; Rutten, Bart P F; van Os, Jim
2017-01-01
An association between white noise speech illusion and psychotic symptoms has been reported in patients and their relatives. This supports the theory that bottom-up and top-down perceptual processes are involved in the mechanisms underlying perceptual abnormalities. However, findings in nonclinical populations have been conflicting. The aim of this study was to examine the association between white noise speech illusion and subclinical expression of psychotic symptoms in a nonclinical sample. Findings were compared to previous results to investigate potential methodology dependent differences. In a general population adolescent and young adult twin sample (n = 704), the association between white noise speech illusion and subclinical psychotic experiences, using the Structured Interview for Schizotypy-Revised (SIS-R) and the Community Assessment of Psychic Experiences (CAPE), was analyzed using multilevel logistic regression analyses. Perception of any white noise speech illusion was not associated with either positive or negative schizotypy in the general population twin sample, using the method by Galdos et al. (2011) (positive: ORadjusted: 0.82, 95% CI: 0.6-1.12, p = 0.217; negative: ORadjusted: 0.75, 95% CI: 0.56-1.02, p = 0.065) and the method by Catalan et al. (2014) (positive: ORadjusted: 1.11, 95% CI: 0.79-1.57, p = 0.557). No association was found between CAPE scores and speech illusion (ORadjusted: 1.25, 95% CI: 0.88-1.79, p = 0.220). For the Catalan et al. (2014) but not the Galdos et al. (2011) method, a negative association was apparent between positive schizotypy and speech illusion with positive or negative affective valence (ORadjusted: 0.44, 95% CI: 0.24-0.81, p = 0.008). Contrary to findings in clinical populations, white noise speech illusion may not be associated with psychosis proneness in nonclinical populations.
Behne, Nicole; Wendt, Beate; Scheich, Henning; Brechmann, André
2006-04-01
In a previous study, we hypothesized that the approach of presenting information-bearing stimuli to one ear and noise to the other ear may be a general strategy to determine hemispheric specialization in auditory cortex (AC). In that study, we confirmed the dominant role of the right AC in directional categorization of frequency modulations by showing that fMRI activation of right but not left AC was sharply emphasized when masking noise was presented to the contralateral ear. Here, we tested this hypothesis using a lexical decision task supposed to be mainly processed in the left hemisphere. Subjects had to distinguish between pseudowords and natural words presented monaurally to the left or right ear either with or without white noise to the other ear. According to our hypothesis, we expected a strong effect of contralateral noise on fMRI activity in left AC. For the control conditions without noise, we found that activation in both auditory cortices was stronger on contralateral than on ipsilateral word stimulation consistent with a more influential contralateral than ipsilateral auditory pathway. Additional presentation of contralateral noise did not significantly change activation in right AC, whereas it led to a significant increase of activation in left AC compared with the condition without noise. This is consistent with a left hemispheric specialization for lexical decisions. Thus our results support the hypothesis that activation by ipsilateral information-bearing stimuli is upregulated mainly in the hemisphere specialized for a given task when noise is presented to the more influential contralateral ear.
Analysis of regularized inversion of data corrupted by white Gaussian noise
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Kekkonen, Hanne; Lassas, Matti; Siltanen, Samuli
2014-01-01
Tikhonov regularization is studied in the case of linear pseudodifferential operator as the forward map and additive white Gaussian noise as the measurement error. The measurement model for an unknown function u(x) is m(x) = Au(x) + δ ε (x), where δ > 0 is the noise magnitude. If ε was an L 2 -function, Tikhonov regularization gives an estimate T α (m) = u∈H r arg min { ||Au-m|| L 2 2 + α||u|| H r 2 } for u where α = α(δ) is the regularization parameter. Here penalization of the Sobolev norm ||u|| H r covers the cases of standard Tikhonov regularization (r = 0) and first derivative penalty (r = 1). Realizations of white Gaussian noise are almost never in L 2 , but do belong to H s with probability one if s < 0 is small enough. A modification of Tikhonov regularization theory is presented, covering the case of white Gaussian measurement noise. Furthermore, the convergence of regularized reconstructions to the correct solution as δ → 0 is proven in appropriate function spaces using microlocal analysis. The convergence of the related finite-dimensional problems to the infinite-dimensional problem is also analysed. (paper)
Directory of Open Access Journals (Sweden)
Syarifah Noor Syakiylla Sayed Daud
2017-08-01
Full Text Available Listening to auditory stimuli during study can give positive and negative influence on human cognitive processing. Thus, it has attracted researchers to conduct studies using various types of auditory stimuli. Some researchers believe that Mozart music and white noise are able to give positive influence on cognitive performance. However, most of the past studies gave more attention towards spatial task. Very little studies have been made on the effect of Mozart music and white noise towards memorizing task. Besides, the effect of these auditory stimuli on task difficulty has also not been studied deeply. Hence, the aims of this study were to investigate the effect of Mozart music and white noise on memory performance with different task difficulty levels; and to propose an effective background stimuli condition for memorization. Experiments have been conducted involving 60 healthy adults that required them to memorize the visual memory task with two difficulty levels; i.e. easy and difficult. Brain signal was recorded during memorization duration using 10-20 electrode placement system of electroencephalography (EEG machine. EEG is a neurological test for measuring and recording the electrical activity of the brain. The effect of sound stimuli on memory performance was evaluated based on memorization test score and brain activity. The wavelet approach was used in processing the EEG data. Based on the memorizing test score result, the subjects are able to memorize better when listening to white noise compared to Mozart music at different difficulty levels. Listening to auditory stimuli can influence the electroencephalography pattern and brain activity. The level of sensory processing and attention increases when listening to white noise which cause the increase of relative gamma (easy level: p-value = 0.005; difficult level: p-value = 0.007 and beta power (easy level: p-value = 0.001; difficult level: p-value = 0.003. Thus, in this study, it is
Lenske, Ariel K; La, Van T
2014-06-01
Animals can use acoustic signals to attract mates and defend territories. As a consequence, background noise that interferes with signal transmission has the potential to reduce fitness, especially in birds that rely on song. While much research on bird song has investigated vocal flexibility in response to urban noise, weather and other birds, the possibility of inter-class acoustic competition from anurans has not been previously studied. Using sound recordings from central Ontario wetlands, we tested if white-throated sparrows (Zonotrichia albicolis) make short-term changes to their singing behaviour in response to chorusing spring peepers (Pseudacris crucifer), as well as to car noise, wind and other bird vocalizations. White-throated sparrow songs that were sung during the spring peeper chorus were shorter with higher minimum frequencies and narrower bandwidths resulting in reduced frequency overlap. Additionally, sparrows were less likely to sing when car noise and the vocalizations of other birds were present. These patterns suggest that birds use multiple adjustment strategies. This is the first report to demonstrate that birds may alter their songs differentially in response to different sources of noise. This article is part of a Special Issue entitled: insert SI title. Copyright © 2014 Elsevier B.V. All rights reserved.
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Mokem Fokou, I.S.; Nono Dueyou Buckjohn, C.; Siewe Siewe, M.; Tchawoua, C.
2016-01-01
In this paper, a sandwiched buckled beam with axial compressive force under Gaussian white noise is considered as a piezoelectric energy harvester. A stochastic averaging method is proposed to analytically predict the system’s response, the stability and the estimation of system’s reliability. By using the generalized harmonic transformation, the Itô differential equations with respect to the mechanical and electrical amplitude are derived through this technique. From these differential equations, we construct the Fokker–Plank–Kolmogorov equation for the electrical and mechanical subsystem where the solution of each equation in the stationary state is a probability density. The mean first passage time (MFPT) is numerically provided in order to study the attractor stability(stable equilibrium point observed in the effective potential) which give rise to the noise-enhanced stability(NES) phenomenon. The mean square response and voltage are obtained for different white noise intensities and others system parameters. The effects of linear damping and noise intensity on the mean square voltage are investigated. We notice that harvested energy can be enhanced by suitable choice of noise intensity and others system parameters. In additional, by combining the random signal with harmonic excitation, the stochastic resonance(SR) phenomenon is observed via the mean residence time(TMR) which give rise to the large amplitude of vibrations and consequently, an optimization of harvested energy. The agreements between the analytical method and those obtained numerically validate the effectiveness of analytical investigations.
Dynamics of double-well Bose–Einstein condensates subject to external Gaussian white noise
International Nuclear Information System (INIS)
Zheng Hanlei; Hao Yajiang; Gu Qiang
2013-01-01
Dynamical properties of the Bose–Einstein condensate in a double-well potential subject to Gaussian white noise are investigated by numerically solving the time-dependent Gross–Pitaevskii equation. The Gaussian white noise is used to describe influence of the random environmental disturbance on the double-well condensate. Dynamical evolutions from three different initial states, the Josephson oscillation state, the running phase and π-mode macroscopic quantum self-trapping states, are considered. It is shown that the system is rather robust with respect to the weak noise whose strength is small and change rate is high. If the evolution time is sufficiently long, the weak noise will finally drive the system to evolve from high-energy states to low-energy states, but in a manner rather different from the energy-dissipation effect. In the presence of strong noise with either large strength or slow change rate, the double-well condensate may exhibit very irregular dynamical behaviours. (paper)
International Nuclear Information System (INIS)
Zhang Ran-Ran; Xu Wei; Yang Gui-Dong; Han Qun
2015-01-01
In this paper, we consider the response analysis of a Duffing–Rayleigh system with fractional derivative under Gaussian white noise excitation. A stochastic averaging procedure for this system is developed by using the generalized harmonic functions. First, the system state is approximated by a diffusive Markov process. Then, the stationary probability densities are derived from the averaged Itô stochastic differential equation of the system. The accuracy of the analytical results is validated by the results from the Monte Carlo simulation of the original system. Moreover, the effects of different system parameters and noise intensity on the response of the system are also discussed. (paper)
International Nuclear Information System (INIS)
Zhou Yu-Rong
2011-01-01
This paper considers the stochastic resonance for a time-delayed mono-stable system, driven by correlated multiplicative and additive white noise. It finds that the output signal-to-noise ratio (SNR) varies non-monotonically with the delayed times. The SNR varies non-monotonically with the increase of the intensities of the multiplicative and additive noise, with the increase of the correlation strength between the two noises, as well as with the system parameter. (general)
Dynamics of a prey-predator system under Poisson white noise excitation
Pan, Shan-Shan; Zhu, Wei-Qiu
2014-10-01
The classical Lotka-Volterra (LV) model is a well-known mathematical model for prey-predator ecosystems. In the present paper, the pulse-type version of stochastic LV model, in which the effect of a random natural environment has been modeled as Poisson white noise, is investigated by using the stochastic averaging method. The averaged generalized Itô stochastic differential equation and Fokker-Planck-Kolmogorov (FPK) equation are derived for prey-predator ecosystem driven by Poisson white noise. Approximate stationary solution for the averaged generalized FPK equation is obtained by using the perturbation method. The effect of prey self-competition parameter ɛ2 s on ecosystem behavior is evaluated. The analytical result is confirmed by corresponding Monte Carlo (MC) simulation.
On signal design by the R/0/ criterion for non-white Gaussian noise channels
Bordelon, D. L.
1977-01-01
The use of the cut-off rate criterion for modulation system design is investigated for channels with non-white Gaussian noise. A signal space representation of the waveform channel is developed, and the cut-off rate for vector channels with additive non-white Gaussian noise and unquantized demodulation is derived. When the signal input to the channel is a continuous random vector, maximization of the cut-off rate with constrained average signal energy leads to a water-filling interpretation of optimal energy distribution in signal space. The necessary condition for a finite signal set to maximize the cut-off rate with constrained energy and an equally likely probability assignment of signal vectors is presented, and an algorithm is outlined for numerically computing the optimum signal set. As an example, the rectangular signal set which has the water-filling average energy distribution and the optimum rectangular set are compared.
Squares of White Noise, SL(2,C) and Kubo - Martin -Schwinger States
Prokhorenko, D. V.
2007-01-01
We investigate the structure of Kubo - Martin - Schwinger (KMS) states on some extension of the universal enveloping algebra of SL(2,C}. We find that there exists a one-to-one correspondence between the set of all covariant KMS states on this algebra and the set of all probability measures d\\mu on the real half-line, which decrease faster than any inverse polynomial. This problem is connected to the problem of KMS states on square of white noise algebra.
Beam-Beam Simulation of Crab Cavity White Noise for LHC Upgrade
Qiang, J; Pieloni, Tatiana; Ohmi, Kazuhito
2015-01-01
High luminosity LHC upgrade will improve the luminosity of the current LHC operation by an order of magnitude. Crab cavity as a critical component for compensating luminosity loss from large crossing angle collision and also providing luminosity leveling for the LHC upgrade is being actively pursued. In this paper, we will report on the study of potential effects of the crab cavity white noise errors on the beam luminosity lifetime based on strong-strong beam-beam simulations.
Stochastic Dynamics of a Time-Delayed Ecosystem Driven by Poisson White Noise Excitation
Directory of Open Access Journals (Sweden)
Wantao Jia
2018-02-01
Full Text Available We investigate the stochastic dynamics of a prey-predator type ecosystem with time delay and the discrete random environmental fluctuations. In this model, the delay effect is represented by a time delay parameter and the effect of the environmental randomness is modeled as Poisson white noise. The stochastic averaging method and the perturbation method are applied to calculate the approximate stationary probability density functions for both predator and prey populations. The influences of system parameters and the Poisson white noises are investigated in detail based on the approximate stationary probability density functions. It is found that, increasing time delay parameter as well as the mean arrival rate and the variance of the amplitude of the Poisson white noise will enhance the fluctuations of the prey and predator population. While the larger value of self-competition parameter will reduce the fluctuation of the system. Furthermore, the results from Monte Carlo simulation are also obtained to show the effectiveness of the results from averaging method.
Hidden symmetries and equilibrium properties of multiplicative white-noise stochastic processes
González Arenas, Zochil; Barci, Daniel G.
2012-12-01
Multiplicative white-noise stochastic processes continue to attract attention in a wide area of scientific research. The variety of prescriptions available for defining them makes the development of general tools for their characterization difficult. In this work, we study equilibrium properties of Markovian multiplicative white-noise processes. For this, we define the time reversal transformation for such processes, taking into account that the asymptotic stationary probability distribution depends on the prescription. Representing the stochastic process in a functional Grassmann formalism, we avoid the necessity of fixing a particular prescription. In this framework, we analyze equilibrium properties and study hidden symmetries of the process. We show that, using a careful definition of the equilibrium distribution and taking into account the appropriate time reversal transformation, usual equilibrium properties are satisfied for any prescription. Finally, we present a detailed deduction of a covariant supersymmetric formulation of a multiplicative Markovian white-noise process and study some of the constraints that it imposes on correlation functions using Ward-Takahashi identities.
Hidden symmetries and equilibrium properties of multiplicative white-noise stochastic processes
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Arenas, Zochil González; Barci, Daniel G
2012-01-01
Multiplicative white-noise stochastic processes continue to attract attention in a wide area of scientific research. The variety of prescriptions available for defining them makes the development of general tools for their characterization difficult. In this work, we study equilibrium properties of Markovian multiplicative white-noise processes. For this, we define the time reversal transformation for such processes, taking into account that the asymptotic stationary probability distribution depends on the prescription. Representing the stochastic process in a functional Grassmann formalism, we avoid the necessity of fixing a particular prescription. In this framework, we analyze equilibrium properties and study hidden symmetries of the process. We show that, using a careful definition of the equilibrium distribution and taking into account the appropriate time reversal transformation, usual equilibrium properties are satisfied for any prescription. Finally, we present a detailed deduction of a covariant supersymmetric formulation of a multiplicative Markovian white-noise process and study some of the constraints that it imposes on correlation functions using Ward–Takahashi identities. (paper)
Delay-induced stochastic bifurcations in a bistable system under white noise
International Nuclear Information System (INIS)
Sun, Zhongkui; Fu, Jin; Xu, Wei; Xiao, Yuzhu
2015-01-01
In this paper, the effects of noise and time delay on stochastic bifurcations are investigated theoretically and numerically in a time-delayed Duffing-Van der Pol oscillator subjected to white noise. Due to the time delay, the random response is not Markovian. Thereby, approximate methods have been adopted to obtain the Fokker-Planck-Kolmogorov equation and the stationary probability density function for amplitude of the response. Based on the knowledge that stochastic bifurcation is characterized by the qualitative properties of the steady-state probability distribution, it is found that time delay and feedback intensity as well as noise intensity will induce the appearance of stochastic P-bifurcation. Besides, results demonstrated that the effects of the strength of the delayed displacement feedback on stochastic bifurcation are accompanied by the sensitive dependence on time delay. Furthermore, the results from numerical simulations best confirm the effectiveness of the theoretical analyses
Delay-induced stochastic bifurcations in a bistable system under white noise
Energy Technology Data Exchange (ETDEWEB)
Sun, Zhongkui, E-mail: sunzk@nwpu.edu.cn; Fu, Jin; Xu, Wei [Department of Applied Mathematics, Northwestern Polytechnical University, Xi' an 710072 (China); Xiao, Yuzhu [Department of Mathematics and Information Science, Chang' an University, Xi' an 710086 (China)
2015-08-15
In this paper, the effects of noise and time delay on stochastic bifurcations are investigated theoretically and numerically in a time-delayed Duffing-Van der Pol oscillator subjected to white noise. Due to the time delay, the random response is not Markovian. Thereby, approximate methods have been adopted to obtain the Fokker-Planck-Kolmogorov equation and the stationary probability density function for amplitude of the response. Based on the knowledge that stochastic bifurcation is characterized by the qualitative properties of the steady-state probability distribution, it is found that time delay and feedback intensity as well as noise intensity will induce the appearance of stochastic P-bifurcation. Besides, results demonstrated that the effects of the strength of the delayed displacement feedback on stochastic bifurcation are accompanied by the sensitive dependence on time delay. Furthermore, the results from numerical simulations best confirm the effectiveness of the theoretical analyses.
Using white noise to gate organic transistors for dynamic monitoring of cultured cell layers.
Rivnay, Jonathan; Leleux, Pierre; Hama, Adel; Ramuz, Marc; Huerta, Miriam; Malliaras, George G; Owens, Roisin M
2015-06-26
Impedance sensing of biological systems allows for monitoring of cell and tissue properties, including cell-substrate attachment, layer confluence, and the "tightness" of an epithelial tissue. These properties are critical for electrical detection of tissue health and viability in applications such as toxicological screening. Organic transistors based on conducting polymers offer a promising route to efficiently transduce ionic currents to attain high quality impedance spectra, but collection of complete impedance spectra can be time consuming (minutes). By applying uniform white noise at the gate of an organic electrochemical transistor (OECT), and measuring the resulting current noise, we are able to dynamically monitor the impedance and thus integrity of cultured epithelial monolayers. We show that noise sourcing can be used to track rapid monolayer disruption due to compounds which interfere with dynamic polymerization events crucial for maintaining cytoskeletal integrity, and to resolve sub-second alterations to the monolayer integrity.
Effects of High Intensity White Noise on Short-Term Memory for Position in a List and Sequence
Daee, Safar; Wilding, J. M.
1977-01-01
Seven experiments are described investigating the effecy of high intensity white noise during the visual presentation of words on a number of short-term memory tasks. Examines results relative to position learning and sequence learning. (Editor/RK)
Zele, Andrew J; Feigl, Beatrix; Kambhampati, Pradeep K; Aher, Avinash; McKeefry, Declan; Parry, Neil; Maguire, John; Murray, Ian; Kremers, Jan
2017-11-01
We introduce a method for determining the impulse response function (IRF) of the ERG derived from responses to temporal white noise (TWN) stimuli. This white noise ERG (wnERG) was recorded in participants with normal trichromatic vision to full-field (Ganzfeld) and 39.3° diameter focal stimuli at mesopic and photopic mean luminances and at different TWN contrasts. The IRF was obtained by cross-correlating the TWN stimulus with the wnERG. We show that wnERG recordings are highly repeatable, with good signal-to-noise ratio, and do not lead to blink artifacts. The wnERG resembles a flash ERG waveform with an initial negativity (N1) followed by a positivity (P1), with amplitudes that are linearly related to stimulus contrast. These N1 and N1-P1 components showed commonalties in implicit times with the a- and b-waves of flash ERGs. There was a clear transition from rod- to cone-driven wnERGs at ∼1 photopic cd.m -2 . We infer that oscillatory potentials found with the flash ERG, but not the wnERG, may reflect retinal nonlinearities due to the compression of energy into a short time period during a stimulus flash. The wnERG provides a new approach to study the physiology of the retina using a stimulation method with adaptation and contrast conditions similar to natural scenes to allow for independent variation of stimulus strength and mean luminance, which is not possible with the conventional flash ERG. The white noise ERG methodology will be of benefit for clinical studies and animal models in the evaluation of hypotheses related to cellular redundancy to understand the effects of disease on specific visual pathways.
Effect of White Noise on Sleep in Patients Admitted to a Coronary Care.
Farokhnezhad Afshar, Pouya; Bahramnezhad, Fatemeh; Asgari, Parvaneh; Shiri, Mahmoud
2016-01-01
Sleep disorders are a common problem in patients in the critical care unit. The objective of the present study was to determine the effect of white noise on the quality of sleep in patients admitted to the CCU. The present study was single-blind, quasi-experimental study. A total of 60 patients were selected using the purposive sampling method. Quality of sleep was measured with PSQI on the first day in admission, then after three nights of admission without any intervention for control group and for the experimental group quality of sleep measured by white noise with intensity of 50-60 dB then Quality of sleep was measured with PSQI. Data were analyzed by SPSS 13 software. The average total sleep time in the control group before the study reached from 7.08 (0.8) to 4.75 (0.66) hours after three nights of hospitalization, while in the experimental group, no significant changes were seen in the average sleep hours (6.69 ± 0.84 vs. 6.92 ± 0.89, P = 0.15).The average minutes of sleep in the control group before the study reached from 12.66 (7.51) to 25.83 (11.75) minutes after a three- night stay, while in the experimental group, no significant changes were observed in the average sleep duration (12.16 ± 7.50 vs. 11 ±6. 07, P = 0.16). The use of white noise is recommended as a method for masking environmental noises, improving sleep, and maintaining sleep in the coronary care unit.
International Nuclear Information System (INIS)
Hoang, Viet Ha
2012-01-01
This paper formulates Bayesian inverse problems for inference in a topological measure space given noisy observations. Conditions for the validity of the Bayes’ formula and the well posedness of the posterior measure are studied. The abstract theory is then applied to Burgers and Hamilton–Jacobi equations on a semi-infinite time interval with forcing functions which are white noise in time. Inference is made on the white noise forcing, assuming the Wiener measure as the prior. (paper)
A comparative study of chaotic and white noise signals in digital watermarking
International Nuclear Information System (INIS)
Mooney, Aidan; Keating, John G.; Pitas, Ioannis
2008-01-01
Digital watermarking is an ever increasing and important discipline, especially in the modern electronically-driven world. Watermarking aims to embed a piece of information into digital documents which their owner can use to prove that the document is theirs, at a later stage. In this paper, performance analysis of watermarking schemes is performed on white noise sequences and chaotic sequences for the purpose of watermark generation. Pseudorandom sequences are compared with chaotic sequences generated from the chaotic skew tent map. In particular, analysis is performed on highpass signals generated from both these watermark generation schemes, along with analysis on lowpass watermarks and white noise watermarks. This analysis focuses on the watermarked images after they have been subjected to common image distortion attacks. It is shown that signals generated from highpass chaotic signals have superior performance than highpass noise signals, in the presence of such attacks. It is also shown that watermarks generated from lowpass chaotic signals have superior performance over the other signal types analysed
The white band disease type II pathogen in Puerto Rico
Directory of Open Access Journals (Sweden)
D. L Gil-Agudelo
2006-12-01
Full Text Available The white band disease type I (WBD-I epizootic event of the early 1980’s resulted in significant changes in the structure and composition of coral communities throughout the wider Caribbean. The disease decimated populations of acroporid corals throughout their geographic distribution and it is still affecting the surviving and recovering populations of these corals in a number of localities in the wider Caribbean. The putative pathogen for this syndrome (WBD-I was never identified. A second pattern of white band was described later as white band type II (WBD-II. A potential pathogen named Vibrio charchariae was identified but Koch’s postulates were never fulfilled. In this work, we present results of a preliminary approach to confirm the identity of the pathogen of WBD-II. During the fall months of 2004, samples of Acropora cervicornis with signs of WBD-II were collected from a small population in Mario reef, an isolated patch reef off La Parguera, southwest coast of Puerto Rico. Bacteria extracted from these samples were isolated in TCBS agar, grown in Glycerol Seawater agar, and then used to inoculate separated, healthy-looking colonies of the same population in the same reef. Isolation, culture, and inoculations of bacteria were conducted under controlled conditions within hours of collection, and no microorganisms that were not already in the reef community were introduced with these experiments. Some of the newly inoculated colonies developed the disease signs within 24 hr. These were subsequently sampled and bacterial re-isolated to be identified, thus complying with the first steps to fulfill Koch ’s postulates for this disease. Rates of advance of the disease signs varied between 0.5 and 2 cm/day. Preliminary analyses indicated that the potential cause of WBD-II is a Vibrio species very close to Vibrio harveyi, a synonymy of V. charchariae. All inoculated coral colonies that developed the signs of WBD-II, behaved as the naturally
Identification and Reduction of Turbomachinery Noise, Phase II
National Aeronautics and Space Administration — Communities near airports are often exposed to high noise levels due to low flying aircraft in the takeoff and landing phases of flight. Propulsion source noise is...
BAYESIAN ANALYSIS OF WHITE NOISE LEVELS IN THE FIVE-YEAR WMAP DATA
International Nuclear Information System (INIS)
Groeneboom, N. E.; Eriksen, H. K.; Gorski, K.; Huey, G.; Jewell, J.; Wandelt, B.
2009-01-01
We develop a new Bayesian method for estimating white noise levels in CMB sky maps, and apply this algorithm to the five-year Wilkinson Microwave Anisotropy Probe (WMAP) data. We assume that the amplitude of the noise rms is scaled by a constant value, α, relative to a pre-specified noise level. We then derive the corresponding conditional density, P(α | s, C l , d), which is subsequently integrated into a general CMB Gibbs sampler. We first verify our code by analyzing simulated data sets, and then apply the framework to the WMAP data. For the foreground-reduced five-year WMAP sky maps and the nominal noise levels initially provided in the five-year data release, we find that the posterior means typically range between α = 1.005 ± 0.001 and α = 1.010 ± 0.001 depending on differencing assembly, indicating that the noise level of these maps are biased low by 0.5%-1.0%. The same problem is not observed for the uncorrected WMAP sky maps. After the preprint version of this letter appeared on astro-ph., the WMAP team has corrected the values presented on their web page, noting that the initially provided values were in fact estimates from the three-year data release, not from the five-year estimates. However, internally in their five-year analysis the correct noise values were used, and no cosmological results are therefore compromised by this error. Thus, our method has already been demonstrated in practice to be both useful and accurate.
Retarding friction versus white noise in the description of heavy ion fusion
International Nuclear Information System (INIS)
Chushnyakova, M.; Gontchar, I.
2014-01-01
We performed the modeling of the collision of 2 spherical nuclei resulting in capture. For this aim the stochastic differential equations are used with the white or colored noise and with the instant or retarding friction, respectively. The dissipative forces are proportional to the squared derivative of the strong nucleus-nucleus interaction potential (SnnP). The SnnP is calculated in the framework of the double folding approach with the density-dependent M3Y NN-forces. Calculations performed for 28 Si+ 144 Sm reaction show that accounting for the fluctuations typically reduces the capture cross sections by not more than 10%. Including the memory effects results in the increase of the capture cross sections by 10-40% depending on the collision energy and presence (or absence) of the fluctuations. In general the memory effects influence the capture capture cross sections stronger than the noise
White noise analysis for the correlation-type elementary motion detectors with half-wave rectifiers.
Ikeda, Hideaki; Aonishi, Toru
2018-06-01
The motion detection mechanism of insects has been attracted attention of many researchers. Several motion-detection models have been proposed on the basis of insect visual system studies. Here, we examine two models, the Hassenstein-Reichardt (HR) model and the two-detector (2D) model. We analytically obtain the mean and variance of the stationary responses of the HR and the 2D models to white noise, and we derive the signal-to-fluctuation-noise ratio (SFNR) to evaluate encoding abilities of the two models. Especially when analyzing the 2D model, we calculate higher-order cumulants of a rectified Gaussian. The results show that the 2D model robustly works almost as well as the HR model in several sets of parameters estimated on the basis of experimental data. Copyright © 2018 Elsevier Ltd. All rights reserved.
Time between plastic displacements of elasto-plastic oscillators subject to Gaussian white noise
DEFF Research Database (Denmark)
Tarp-Johansen, Niels Jacob; Ditlevsen, Ove Dalager
2001-01-01
A one degree of freedom elasto-plastic oscillator subject to stationary Gaussian white noise has a plastic displacement response process of intermittent character. During shorter or longer time intervals the oscillator vibrates within the elastic domain without undergoing any plastic displacements...... between the clumps of plastic displacements. This is needed for a complete description of the plastic displacement process. A quite accurate fast simulation procedure is presented based on an amplitude model to determine the short waiting times in the transient regime of the elastic vibrations existing...
Kalman filter based fault diagnosis of networked control system with white noise
Institute of Scientific and Technical Information of China (English)
Yanwei WANG; Ying ZHENG
2005-01-01
The networked control system NCS is regarded as a sampled control system with output time-variant delay.White noise is considered in the model construction of NCS.By using the Kalman filter theory to compute the filter parameters,a Kalman filter is constructed for this NCS.By comparing the output of the filter and the practical system,a residual is generated to diagnose the sensor faults and the actuator faults.Finally,an example is given to show the feasibility of the approach.
On some Filtration Procedure for Jump Markov Process Observed in White Gaussian Noise
Khas'minskii, Rafail Z.; Lazareva, Betty V.
1992-01-01
The importance of optimal filtration problem for Markov chain with two states observed in Gaussian white noise (GWN) for a lot of concrete technical problems is well known. The equation for a posterior probability $\\pi(t)$ of one of the states was obtained many years ago. The aim of this paper is to study a simple filtration method. It is shown that this simplified filtration is asymptotically efficient in some sense if the diffusion constant of the GWN goes to 0. Some advantages of this proc...
Glover, K.; Willems, J. C.
1973-01-01
Consider the situation in which the unknown parameters of a stationary linear system may be parametrized by a set of unknown parameters. The question thus arises of when such a set of parameters can be uniquely identified on the basis of observed data. This problem is considered here both in the case of input and output observations and in the case of output observations in the presence of a white noise input. Conditions for local identifiability are derived for both situations and a sufficient condition for global identifiability is given for the former situation, i.e., when simultaneous input and output observations are available.
Energy Technology Data Exchange (ETDEWEB)
Ganguly, Jayanta [Department of Chemistry, Brahmankhanda Basapara High School, Basapara, Birbhum 731215, West Bengal (India); Ghosh, Manas, E-mail: pcmg77@rediffmail.com [Department of Chemistry, Physical Chemistry Section, Visva Bharati University, Santiniketan, Birbhum 731 235, West Bengal (India)
2014-05-07
We investigate the profiles of diagonal components of frequency-dependent first nonlinear (β{sub xxx} and β{sub yyy}) optical response of repulsive impurity doped quantum dots. We have assumed a Gaussian function to represent the dopant impurity potential. This study primarily addresses the role of noise on the polarizability components. We have invoked Gaussian white noise consisting of additive and multiplicative characteristics (in Stratonovich sense). The doped system has been subjected to an oscillating electric field of given intensity, and the frequency-dependent first nonlinear polarizabilities are computed. The noise characteristics are manifested in an interesting way in the nonlinear polarizability components. In case of additive noise, the noise strength remains practically ineffective in influencing the optical responses. The situation completely changes with the replacement of additive noise by its multiplicative analog. The replacement enhances the nonlinear optical response dramatically and also causes their maximization at some typical value of noise strength that depends on oscillation frequency.
Energy Technology Data Exchange (ETDEWEB)
McConnell, Gail [Centre for Biophotonics, Strathclyde Institute for Biomedical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow, G4 0NR (United Kingdom)
2005-08-07
Intensity correlations of a Ti : sapphire, Kr/Ar and a white-light supercontinuum were performed to quantify the typical signal amplitude fluctuations and hence ascertain the comparative output stability of the white-light supercontinuum source for confocal laser scanning microscopy (CLSM). Intensity correlations across a two-pixel sample (n = 1000) of up to 98%, 95% and 94% were measured for the Ti : sapphire, Kr/Ar and white-light supercontinuum source, respectively. The white-light supercontinuum noise level is therefore acceptable for CLSM, with the added advantage of wider wavelength flexibility over traditional CLSM excitation sources. The relatively low-noise white-light supercontinuum was then used to perform multiple wavelength sequential CLSM of guinea pig detrusor to confirm the reliability of the system and to demonstrate system flexibility.
Aban, C. J. G.; Bacolod, R. O.; Confesor, M. N. P.
2015-06-01
A The White Noise Path Integral Approach is used in evaluating the B-cell density or the number of B-cell per unit volume for a basic type of immune system response based on the modeling done by Perelson and Wiegel. From the scaling principles of Perelson [1], the B- cell density is obtained where antigens and antibodies mutates and activation function f(|S-SA|) is defined describing the interaction between a specific antigen and a B-cell. If the activation function f(|S-SA|) is held constant, the major form of the B-cell density evaluated using white noise analysis is similar to the form of the B-cell density obtained by Perelson and Wiegel using a differential approach.A piecewise linear functionis also used to describe the activation f(|S-SA|). If f(|S-SA|) is zero, the density decreases exponentially. If f(|S-SA|) = S-SA-SB, the B- cell density increases exponentially until it reaches a certain maximum value. For f(|S-SA|) = 2SA-SB-S, the behavior of B-cell density is oscillating and remains to be in small values.
A new algebraic white-noise modal combination rule - GAC(A)
International Nuclear Information System (INIS)
Mertens, P.G.
1994-01-01
It is a well known fact that above the rigid frequency the maximum dynamic modal responses even with different multiple supports can be combined algebraically. Below the rigid frequency, and more specifically in the white-noise (amplified) region of the response spectrum, algebraic modal combination is still a matter of controversy, demonstrated e.g. by the NRC R.G. 1.92 requirement to take the absolute values of the modal responses in heuristic modal combination rules; whereas algebraic support combination is only allowed in conjunction with the envelope support response spectrum (ERS). Such regulatory requirements can lead to unrealistically high calculated responses e.g. in the coupled analysis of light secondary systems attached to heavy primary structures and in the decoupled analysis of systems when the centres of mass and stiffness do not coincide, or when the ERS is used. A new Generalised Algebraic Combination (GAC) methodology has been theoretically developed which allows practical algebraic modal and support combination over the whole frequency range of multiple support spectra. The present paper deals with the GAC-(A) i.e. the modal combination version in the white noise region of a single response spectrum and more specifically its time history integration validation, which shows that this new modal combination rule can satisfy any realistic conservatism that may be required by regulatory institutions. (orig.)
Cueing properties of the decrease of white noise intensity for avoidance conditioning in cats.
Zieliński, K
1979-01-01
In the main experiment two groups of 6 cats each were trained in active bar-pressing avoidance to a CS consisting of either a 10 dB or 20 dB decrease of the background white noise of 70 dB intensity. The two groups did not differ in rapidity of learning, however cats trained to the greater change .in background noise performed avoidance responses with shorter latencies than did cats trained to smaller change. Within-groups comparisons of cumulative distributions of response latencies for consecutive Vincentized fifths of avoidance acquisition showed the greatest changes in the region of latencies longer than the median latency of instrumental responses. On the other hand, the effects of CS intensity found in between-groups comparisons were located in the region of latencies shorter than the median latency of either group. Comparisons with data obtained in a complementary experiment employing additional 17 cats showed that subjects trained to stimuli less intense than the background noise level were marked by an exceptionally low level of avoidance responding with latencies shorter than 1.1 s, which was lower than expected from the probability of intertrial responses for this period of time. Due to this property of stimuli less intense than the background, the distributions of response latencies were moved to the right, in effect, prefrontal lesions influenced a greater part of latency distributions than in cats trained to stimuli more intense than the background.
Zhang, Bo; Kagawa, Keiichiro; Takasawa, Taishi; Seo, Min Woong; Yasutomi, Keita; Kawahito, Shoji
2014-01-16
In extremely low-light conditions, random telegraph signal (RTS) noise and dark current white defects become visible. In this paper, a multi-aperture imaging system and selective averaging method which removes the RTS noise and the dark current white defects by minimizing the synthetic sensor noise at every pixel is proposed. In the multi-aperture imaging system, a very small synthetic F-number which is much smaller than 1.0 is achieved by increasing optical gain with multiple lenses. It is verified by simulation that the effective noise normalized by optical gain in the peak of noise histogram is reduced from 1.38e⁻ to 0.48 e⁻ in a 3 × 3-aperture system using low-noise CMOS image sensors based on folding-integration and cyclic column ADCs. In the experiment, a prototype 3 × 3-aperture camera, where each aperture has 200 × 200 pixels and an imaging lens with a focal length of 3.0 mm and F-number of 3.0, is developed. Under a low-light condition, in which the maximum average signal is 11e⁻ per aperture, the RTS and dark current white defects are removed and the peak signal-to-noise ratio (PSNR) of the image is increased by 6.3 dB.
Iterative noise removal from temperature and density profiles in the TJ-II Thomson scattering
International Nuclear Information System (INIS)
Farias, G.; Dormido-Canto, S.; Vega, J.; Santos, M.; Pastor, I.; Fingerhuth, S.; Ascencio, J.
2014-01-01
TJ-II Thomson Scattering diagnostic provides temperature and density profiles of plasma. The CCD camera acquires images that are corrupted with some kind of noise called stray-light. This noise degrades both image contrast and measurement accuracy, which could produce unreliable profiles of the diagnostic. So far, several approaches have been applied in order to decrease the noise in the TJ-II Thomson scattering images. Since the presence of the noise is not global but located in some particular regions of the image, advanced processing techniques are needed. However such methods require of manual fine-tuning of parameters to reach a good performance. In this contribution, an iterative image processing approach is applied in order to reduce the stray light effects in the images of the TJ-II Thomson scattering diagnostic. The proposed solution describes how the noise can be iteratively reduced in the images when a key parameter is automatically adjusted during the iterative process
Iterative noise removal from temperature and density profiles in the TJ-II Thomson scattering
Energy Technology Data Exchange (ETDEWEB)
Farias, G., E-mail: gonzalo.farias@ucv.cl [Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147, Valparaíso (Chile); Dormido-Canto, S., E-mail: sebas@dia.uned.es [Departamento de Informática y Automática, UNED, 28040 Madrid (Spain); Vega, J., E-mail: jesus.vega@ciemat.es [Asociación EURATOM/CIEMAT para Fusión, Avd. Complutense 22, 28040 Madrid (Spain); Santos, M., E-mail: msantos@ucm.es [Departamento de Arquitectura de Computadores y Automática, Universidad Complutense de Madrid, 28040 Madrid (Spain); Pastor, I., E-mail: ignacio.pastor@ciemat.es [Asociación EURATOM/CIEMAT para Fusión, Avd. Complutense 22, 28040 Madrid (Spain); Fingerhuth, S., E-mail: sebastian.fingerhuth@ucv.cl [Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147, Valparaíso (Chile); Ascencio, J., E-mail: j_ascencio21@hotmail.com [Pontificia Universidad Católica de Valparaíso, Av. Brasil 2147, Valparaíso (Chile)
2014-05-15
TJ-II Thomson Scattering diagnostic provides temperature and density profiles of plasma. The CCD camera acquires images that are corrupted with some kind of noise called stray-light. This noise degrades both image contrast and measurement accuracy, which could produce unreliable profiles of the diagnostic. So far, several approaches have been applied in order to decrease the noise in the TJ-II Thomson scattering images. Since the presence of the noise is not global but located in some particular regions of the image, advanced processing techniques are needed. However such methods require of manual fine-tuning of parameters to reach a good performance. In this contribution, an iterative image processing approach is applied in order to reduce the stray light effects in the images of the TJ-II Thomson scattering diagnostic. The proposed solution describes how the noise can be iteratively reduced in the images when a key parameter is automatically adjusted during the iterative process.
Yang, Yongge; Xu, Wei; Yang, Guidong; Jia, Wantao
2016-08-01
The Poisson white noise, as a typical non-Gaussian excitation, has attracted much attention recently. However, little work was referred to the study of stochastic systems with fractional derivative under Poisson white noise excitation. This paper investigates the stationary response of a class of quasi-linear systems with fractional derivative excited by Poisson white noise. The equivalent stochastic system of the original stochastic system is obtained. Then, approximate stationary solutions are obtained with the help of the perturbation method. Finally, two typical examples are discussed in detail to demonstrate the effectiveness of the proposed method. The analysis also shows that the fractional order and the fractional coefficient significantly affect the responses of the stochastic systems with fractional derivative.
International Nuclear Information System (INIS)
Yang, Yongge; Xu, Wei; Yang, Guidong; Jia, Wantao
2016-01-01
The Poisson white noise, as a typical non-Gaussian excitation, has attracted much attention recently. However, little work was referred to the study of stochastic systems with fractional derivative under Poisson white noise excitation. This paper investigates the stationary response of a class of quasi-linear systems with fractional derivative excited by Poisson white noise. The equivalent stochastic system of the original stochastic system is obtained. Then, approximate stationary solutions are obtained with the help of the perturbation method. Finally, two typical examples are discussed in detail to demonstrate the effectiveness of the proposed method. The analysis also shows that the fractional order and the fractional coefficient significantly affect the responses of the stochastic systems with fractional derivative.
Energy Technology Data Exchange (ETDEWEB)
Yang, Yongge; Xu, Wei, E-mail: weixu@nwpu.edu.cn; Yang, Guidong; Jia, Wantao [Department of Applied Mathematics, Northwestern Polytechnical University, Xi' an 710072 (China)
2016-08-15
The Poisson white noise, as a typical non-Gaussian excitation, has attracted much attention recently. However, little work was referred to the study of stochastic systems with fractional derivative under Poisson white noise excitation. This paper investigates the stationary response of a class of quasi-linear systems with fractional derivative excited by Poisson white noise. The equivalent stochastic system of the original stochastic system is obtained. Then, approximate stationary solutions are obtained with the help of the perturbation method. Finally, two typical examples are discussed in detail to demonstrate the effectiveness of the proposed method. The analysis also shows that the fractional order and the fractional coefficient significantly affect the responses of the stochastic systems with fractional derivative.
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Lazarov, Boyan Stefanov
2003-01-01
frame. A suitable number of the lower floors has been considered to represent the soil both as a filter of a white noise base rock excitation and as a simplified model for soil structure interaction. In the present paper the Slepian model is applied to obtain plastic displacement distributions...... frame with partial or full feed back from the movement of the top mass to the second and the first mass (top soil layer mass and base rock mass, respectively). Keywords: Clough-Penzien filtered white noise excitation, elasto-plastic shear frame oscillator, plastic displacement distributions, simplified...
International Nuclear Information System (INIS)
Kwok, Sau Fa
2012-01-01
A Langevin equation with multiplicative white noise and its corresponding Fokker–Planck equation are considered in this work. From the Fokker–Planck equation a transformation into the Wiener process is provided for different orders of prescription in discretization rule for the stochastic integrals. A few applications are also discussed. - Highlights: ► Fokker–Planck equation corresponding to the Langevin equation with mul- tiplicative white noise is presented. ► Transformation of diffusion processes into the Wiener process in different prescriptions is provided. ► The prescription parameter is associated with the growth rate for a Gompertz-type model.
Sheliga, Boris M; Quaia, Christian; FitzGibbon, Edmond J; Cumming, Bruce G
2016-01-01
White noise stimuli are frequently used to study the visual processing of broadband images in the laboratory. A common goal is to describe how responses are derived from Fourier components in the image. We investigated this issue by recording the ocular-following responses (OFRs) to white noise stimuli in human subjects. For a given speed we compared OFRs to unfiltered white noise with those to noise filtered with band-pass filters and notch filters. Removing components with low spatial frequency (SF) reduced OFR magnitudes, and the SF associated with the greatest reduction matched the SF that produced the maximal response when presented alone. This reduction declined rapidly with SF, compatible with a winner-take-all operation. Removing higher SF components increased OFR magnitudes. For higher speeds this effect became larger and propagated toward lower SFs. All of these effects were quantitatively well described by a model that combined two factors: (a) an excitatory drive that reflected the OFRs to individual Fourier components and (b) a suppression by higher SF channels where the temporal sampling of the display led to flicker. This nonlinear interaction has an important practical implication: Even with high refresh rates (150 Hz), the temporal sampling introduced by visual displays has a significant impact on visual processing. For instance, we show that this distorts speed tuning curves, shifting the peak to lower speeds. Careful attention to spectral content, in the light of this nonlinearity, is necessary to minimize the resulting artifact when using white noise patterns undergoing apparent motion.
Traffic noise in Hyderabad city, part-II. vehicular contribution to road traffic noise
International Nuclear Information System (INIS)
Sheikh, G.H.
2001-01-01
The results of a road traffic noise survey carried out in Hyderabad city showed that the levels of traffic noise in the City are alarmingly high and much beyond the comfortable limits. There, in order to investigate the level of the noise emitted by different types of vehicles plying on the city roads and to assess their individual contribution to high level traffic noise, studies have been carried out on the measurement of noise emitted by motorcycles, buses, auto-rickshaws, and motor vehicle horns as they normally move on the city roads. The data collected has been analyzed for L/sub v99/, L/sub v90/, L/sub v50/, L/sub v10/ and L/sub v1/ and results are discussed with reference to the existing motor vehicle rules in Pakistan and motor vehicle noise emission limits set by the EEC and other developed countries. Some suggestion have also been made to limit high level traffic noise. (author)
Analysis of piezoelectric energy harvester under modulated and filtered white Gaussian noise
Quaranta, Giuseppe; Trentadue, Francesco; Maruccio, Claudio; Marano, Giuseppe C.
2018-05-01
This paper proposes a comprehensive method for the electromechanical probabilistic analysis of piezoelectric energy harvesters subjected to modulated and filtered white Gaussian noise (WGN) at the base. Specifically, the dynamic excitation is simulated by means of an amplitude-modulated WGN, which is filtered through the Clough-Penzien filter. The considered piezoelectric harvester is a cantilever bimorph modeled as Euler-Bernoulli beam with a concentrated mass at the free-end, and its global behavior is approximated by the fundamental vibration mode (which is tuned with the dominant frequency of the dynamic input). A resistive electrical load is considered in the circuit. Once the Lyapunov equation of the coupled electromechanical problem has been formulated, an original and efficient semi-analytical procedure is proposed to estimate mean and standard deviation of the electrical energy extracted from the piezoelectric layers.
Langevin dynamics for vector variables driven by multiplicative white noise: A functional formalism
Moreno, Miguel Vera; Arenas, Zochil González; Barci, Daniel G.
2015-04-01
We discuss general multidimensional stochastic processes driven by a system of Langevin equations with multiplicative white noise. In particular, we address the problem of how time reversal diffusion processes are affected by the variety of conventions available to deal with stochastic integrals. We present a functional formalism to build up the generating functional of correlation functions without any type of discretization of the Langevin equations at any intermediate step. The generating functional is characterized by a functional integration over two sets of commuting variables, as well as Grassmann variables. In this representation, time reversal transformation became a linear transformation in the extended variables, simplifying in this way the complexity introduced by the mixture of prescriptions and the associated calculus rules. The stochastic calculus is codified in our formalism in the structure of the Grassmann algebra. We study some examples such as higher order derivative Langevin equations and the functional representation of the micromagnetic stochastic Landau-Lifshitz-Gilbert equation.
Retarding friction versus white noise in the description of heavy ion fusion
Chushnyakova, Maria; Gontchar, Igor
2014-03-01
We performed modeling of the collision of two spherical nuclei resulting in capture. For this aim the stochastic differential equations are used with the white or colored noise and with the instant or retarding friction, respectively. The dissipative forces are proportional to the squared derivative of the strong nucleus-nucleus interaction potential (SnnP). The SnnP is calculated in the framework of the double folding approach with the density-dependent M3Y NN-forces. Calculations performed for 28Si+144Sm reaction show that accounting for the fluctuations typically reduces the capture cross sections by not more than 10%. In contradistinction, the influence of the memory effects is found resulting in about 20% enhancement of the cross section.
Wavelet Co-movement Significance Testing with Respect to Gaussian White Noise Background
Directory of Open Access Journals (Sweden)
Poměnková Jitka
2018-01-01
Full Text Available The paper deals with significance testing of time series co-movement measured via wavelet analysis, namely via the wavelet cross-spectra. This technique is very popular for its better time resolution compare to other techniques. Such approach put in evidence the existence of both long-run and short-run co-movement. In order to have better predictive power it is suitable to support and validate obtained results via some testing approach. We investigate the test of wavelet power cross-spectrum with respect to the Gaussian white noise background with the use of the Bessel function. Our experiment is performed on real data, i.e. seasonally adjusted quarterly data of gross domestic product of the United Kingdom, Korea and G7 countries. To validate the test results we perform Monte Carlo simulation. We describe the advantages and disadvantages of both approaches and formulate recommendations for its using.
Global Pressure of One-Dimensional Polydisperse Granular Gases Driven by Gaussian White Noise
International Nuclear Information System (INIS)
Chen Zhiyuan; Zhang Duanming; Yang Fengxia; Huang Mingtao; Li Rui; Zhang Ling; Zhu Hongying
2007-01-01
We study the global pressure of a one-dimensional polydisperse granular gases system for the first time, in which the size distribution of particles has the fractal characteristic and the inhomogeneity is described by a fractal dimension D. The particles are driven by Gaussian white noise and subject to inelastic mutual collisions. We define the global pressure P of the system as the impulse transferred across a surface in a unit of time, which has two contributions, one from the translational motion of particles and the other from the collisions. Explicit expression for the global pressure in the steady state is derived. By molecular dynamics simulations, we investigate how the inelasticity of collisions and the inhomogeneity of the particles influence the global pressure. The simulation results indicate that the restitution coefficient e and the fractal dimension D have significant effect on the pressure.
Halyo, N.; Caglayan, A. K.
1976-01-01
This paper considers the control of a continuous linear plant disturbed by white plant noise when the control is constrained to be a piecewise constant function of time; i.e. a stochastic sampled-data system. The cost function is the integral of quadratic error terms in the state and control, thus penalizing errors at every instant of time while the plant noise disturbs the system continuously. The problem is solved by reducing the constrained continuous problem to an unconstrained discrete one. It is shown that the separation principle for estimation and control still holds for this problem when the plant disturbance and measurement noise are Gaussian.
On signal design by the R sub 0 criterion for non-white Gaussian noise channels
Bordelon, D. L.
1976-01-01
The use of the R sub 0 criterion for modulation system design is investigated for channels with non-white Gaussian noise. A signal space representation of the waveform channel is developed, and the cut-off rate R sub 0 for vector channels with additive nonwhite Gaussian noise and unquantized demodulation is derived. When the signal unput to the channel is a continuous random vector, maximization of R sub 0 with constrained average signal energy leads to a water-filling interpretation of optimal energy distribution in signal space. The necessary condition for a finite signal set to maximize R sub 0 with constrained energy and an equally likely probability assignment of signal vectors is presented, and an algorithm is outlined for numerically computing the optimum signal set. A necessary condition on a constrained energy, finite signal set is found which maximizes a Taylor series approximation of R sub 0. This signal set is compared with the finite signal set which has the water-filling average energy distribution.
Crino, Ondi L; Johnson, Erin E; Blickley, Jessica L; Patricelli, Gail L; Breuner, Creagh W
2013-06-01
Roads have been associated with behavioral and physiological changes in wildlife. In birds, roads decrease reproductive success and biodiversity and increase physiological stress. Although the consequences of roads on individuals and communities have been well described, the mechanisms through which roads affect birds remain largely unexplored. Here, we examine one mechanism through which roads could affect birds: traffic noise. We exposed nestling mountain white-crowned sparrows (Zonotrichia leucophrys oriantha) to experimentally elevated traffic noise for 5 days during the nestling period. Following exposure to traffic noise we measured nestling stress physiology, immune function, body size, condition and survival. Based on prior studies, we expected the traffic noise treatment to result in elevated stress hormones (glucocorticoids), and declines in immune function, body size, condition and survival. Surprisingly, nestlings exposed to traffic noise had lower glucocorticoid levels and improved condition relative to control nests. These results indicate that traffic noise does affect physiology and development in white-crowned sparrows, but not at all as predicted. Therefore, when evaluating the mechanisms through which roads affect avian populations, other factors (e.g. edge effects, pollution and mechanical vibration) may be more important than traffic noise in explaining elevated nestling stress responses in this species.
International Nuclear Information System (INIS)
Stan, Cristina; Cristescu, Cristina Maria; Alexandroaei, D.; Cristescu, C.P.
2014-01-01
Highlights: •We study the white Gaussian noise effect on the fractality of plasma fluctuations. •Multifractality strength is increased by the noise, at all inter-anode voltages. •New positive influence of noise resulting in an increasing of the predictability. •Identifying the fluctuations nature: chaotic or stochastic by multifractal analysis. •Noise changes the position of the maximum in the singularity spectra. - Abstract: In this work we investigate the influence of white Gaussian noise on the fluctuations in the plasma of a symmetrical discharge using multifractal detrended fluctuation analysis. We observe that in the range of noise intensity used in our study, the multifractality strength is increased by the noise, at all values of the inter-anode voltage, both for original and filtered time-series. This is interpreted as a new positive influence of noise because this effect can be understood as an increasing in the predictability on the dynamics in a time-series. A constructive influence of noise can appear only for fluctuations with underlying chaotic dynamics. The shuffling analysis demonstrates that the multifractality is purely a consequence of the correlations of the fluctuations. The noise influence is also observed in the change of the position of the maximum in the singularity spectra. The multifractal detrended cross correlation between light intensity and current intensity demonstrates that the fluctuations in both parameters are generated by the same physical processes though they are very different in nature: one is a local parameter and the other is a global one
Kalson, S.
1986-01-01
Previous work in the area of choosing channel quantization levels for a additive white Gaussian noise channel composed of one receiver-demodulator is reviewed, and how this applies to the Deep Space Network composed of several receiver-demodulators (space diversity reception) is shown. Viterbi decoding for the resulting quantized channel is discussed.
Lee, Kyu-Yong; Lee, Tae-Ho; Yoon, So-Jeong; Cho, Yang Seok; Choi, June-Seek; Kim, Hyun Taek
2010-06-14
In the present study, we investigated the neural correlates underlying the perception of emotion in response to facial stimuli in order to elucidate the extent to which emotional perception is affected by the top-down process. Subjects performed a forced, two-choice emotion discrimination task towards ambiguous visual stimuli consisted of emotional faces embedded in different levels of visual white noise, including white noise-alone stimuli. ERP recordings and behavioral responses were analyzed according to the four response categories: hit, miss, false alarm and correct rejection. We observed enlarged EPN and LPP amplitudes when subjects reported seeing fearful faces and a typical emotional EPN response in the white noise-alone conditions when fearful faces were not presented. The two components of the ERP data which imply the characteristic modulation reflecting emotional processing showed the type of emotion each individual subjectively perceived. The results suggest that top-down modulations might be indispensable for emotional perception, which consists of two distinct stages of stimulus processing in the brain. (c) 2010 Elsevier B.V. All rights reserved.
Directory of Open Access Journals (Sweden)
Feilu Wang
2014-04-01
Full Text Available Research on tactile sensors to enhance their flexibility and ability of multi- dimensional information detection is a key issue to develop humanoid robots. In view of that the tactile sensor is often affected by noise, this paper adds different white Gaussian noises (WGN into the ideal model of flexible tactile sensors based on conductive rubber purposely, then improves the standard radial basis function neural network (RNFNN to deal with the noises. The modified RBFNN is applied to approximate and decouple the mapping relationship between row-column resistance with WGNs and three-dimensional deformation. Numerical experiments demonstrate that the decoupling result of the deformation for the sensor is quite good. The results show that the improved RBFNN which doesn’t rely on the mathematical model of the system has good anti-noise ability and robustness.
LCD displays performance comparison by MTF measurement using the white noise stimulus method
Mitjà, Carles; Escofet, Jaume
2011-01-01
The amount of images produced to be viewed as soft copies on output displays are significantly increasing. This growing occurs at the expense of the images targeted to hard copy versions on paper or any other physical support. Even in the case of high quality hard copy production, people working in professional imaging uses different displays in selecting, editing, processing and showing images, from laptop screen to specialized high end displays. Then, the quality performance of these devices is crucial in the chain of decisions to be taken in image production. Metrics of this quality performance can help in the equipment acquisition. Different metrics and methods have been described to determine the quality performance of CRT and LCD computer displays in clinical area. One of most important metrics in this field is the device spatial frequency response obtained measuring the modulation transfer function (MTF). This work presents a comparison between the MTF of three different LCD displays, Apple MacBook Pro 15", Apple LED Cinema Display 24" and Apple iPhone4, measured by the white noise stimulus method, over vertical and horizontal directions. Additionally, different displays show particular pixels structure pattern. In order to identify this pixel structure, a set of high magnification images is taken from each display to be related with the respective vertical and horizontal MTF.
Noise is all around you, from televisions and radios to lawn mowers and washing machines. Normally, you ... sensitive structures of the inner ear and cause noise-induced hearing loss. More than 30 million Americans ...
International Nuclear Information System (INIS)
Yang Yong-Ge; Xu Wei; Sun Ya-Hui; Gu Xu-Dong
2016-01-01
This paper aims to investigate the stochastic response of the van der Pol (VDP) oscillator with two kinds of fractional derivatives under Gaussian white noise excitation. First, the fractional VDP oscillator is replaced by an equivalent VDP oscillator without fractional derivative terms by using the generalized harmonic balance technique. Then, the stochastic averaging method is applied to the equivalent VDP oscillator to obtain the analytical solution. Finally, the analytical solutions are validated by numerical results from the Monte Carlo simulation of the original fractional VDP oscillator. The numerical results not only demonstrate the accuracy of the proposed approach but also show that the fractional order, the fractional coefficient and the intensity of Gaussian white noise play important roles in the responses of the fractional VDP oscillator. An interesting phenomenon we found is that the effects of the fractional order of two kinds of fractional derivative items on the fractional stochastic systems are totally contrary. (paper)
International Nuclear Information System (INIS)
Yue Xiao-Le; Xu Wei; Zhang Ying; Wang Liang
2015-01-01
The piezomagnetoelastic energy harvester system subjected to harmonic and Poisson white noise excitations is studied by using the generalized cell mapping method. The transient and stationary probability density functions (PDFs) of response based on the global viewpoint are obtained by the matrix analysis method. Monte Carlo simulation results verify the accuracy of this method. It can be observed that evolutionary direction of transient and stationary PDFs is in accordance with the unstable manifold for this system, and a stochastic P-bifurcation occurs as the intensity of Poisson white noise increases. This study presents an efficient numerical tool to solve the stochastic response of a three-dimensional dynamical system and provides a new idea to analyze the energy harvester system. (paper)
Energy Technology Data Exchange (ETDEWEB)
Cui, Jianbo, E-mail: jianbocui@lsec.cc.ac.cn [Institute of Computational Mathematics and Scientific/Engineering Computing, Chinese Academy of Sciences, Beijing, 100190 (China); Hong, Jialin, E-mail: hjl@lsec.cc.ac.cn [Institute of Computational Mathematics and Scientific/Engineering Computing, Chinese Academy of Sciences, Beijing, 100190 (China); Liu, Zhihui, E-mail: liuzhihui@lsec.cc.ac.cn [Institute of Computational Mathematics and Scientific/Engineering Computing, Chinese Academy of Sciences, Beijing, 100190 (China); Zhou, Weien, E-mail: weienzhou@nudt.edu.cn [College of Science, National University of Defense Technology, Changsha 410073 (China)
2017-08-01
We indicate that the nonlinear Schrödinger equation with white noise dispersion possesses stochastic symplectic and multi-symplectic structures. Based on these structures, we propose the stochastic symplectic and multi-symplectic methods, which preserve the continuous and discrete charge conservation laws, respectively. Moreover, we show that the proposed methods are convergent with temporal order one in probability. Numerical experiments are presented to verify our theoretical results.
International Nuclear Information System (INIS)
Cui, Jianbo; Hong, Jialin; Liu, Zhihui; Zhou, Weien
2017-01-01
We indicate that the nonlinear Schrödinger equation with white noise dispersion possesses stochastic symplectic and multi-symplectic structures. Based on these structures, we propose the stochastic symplectic and multi-symplectic methods, which preserve the continuous and discrete charge conservation laws, respectively. Moreover, we show that the proposed methods are convergent with temporal order one in probability. Numerical experiments are presented to verify our theoretical results.
Qiao, Yan; Xu, Wei; Jia, Wantao; Han, Qun
2017-05-01
Variable-mass systems have received widespread attention and show prominent significance with the explosive development of micro- and nanotechnologies, so there is a growing need to study the influences of mass disturbances on systems. This paper is devoted to investigating the stochastic response of a variable-mass system subject to weakly random excitation, in which the mass disturbance is modeled as a Poisson white noise. Firstly, the original system is approximately replaced by the associated conservative system with small disturbance based on the Taylor expansion technique. Then the stationary response of the approximate system is obtained by applying the stochastic averaging method. At last, a representative variable-mass oscillator is worked out to illustrate the effectiveness of the analytical solution by comparing with Monte Carlo simulation. The relative change of mean-square displacement is used to measure the influences of mass disturbance on system responses. Results reveal that the stochastic responses are more sensitive to mass disturbance for some system parameters. It is also found that the influences of Poisson white noise as the mass disturbance on system responses are significantly different from that of Gaussian white noise of the same intensity.
Kawase, Tetsuaki; Maki, Atsuko; Kanno, Akitake; Nakasato, Nobukazu; Sato, Mika; Kobayashi, Toshimitsu
2012-01-16
The different response characteristics of the different auditory cortical responses under conventional central masking conditions were examined by comparing the effects of contralateral white noise on the cortical component of 40-Hz auditory steady state fields (ASSFs) and the N100 m component in auditory evoked fields (AEFs) for tone bursts using a helmet-shaped magnetoencephalography system in 8 healthy volunteers (7 males, mean age 32.6 years). The ASSFs were elicited by monaural 1000 Hz amplitude modulation tones at 80 dB SPL, with the amplitude modulated at 39 Hz. The AEFs were elicited by monaural 1000 Hz tone bursts of 60 ms duration (rise and fall times of 10 ms, plateau time of 40 ms) at 80 dB SPL. The results indicated that continuous white noise at 70 dB SPL presented to the contralateral ear did not suppress the N100 m response in either hemisphere, but significantly reduced the amplitude of the 40-Hz ASSF in both hemispheres with asymmetry in that suppression of the 40-Hz ASSF was greater in the right hemisphere. Different effects of contralateral white noise on these two responses may reflect different functional auditory processes in the cortices. Copyright © 2011 Elsevier Inc. All rights reserved.
Influence of lasers with non-white frequency noise on the design of coherent optical links
DEFF Research Database (Denmark)
Kakkar, Aditya; Navarro, Jaime Rodrigo; Schatz, Richard
2017-01-01
We experimentally demonstrate for a 28 Gbaud 64-QAM metro link that the LO frequency noise causes timing impairment. Results show the existence of LO frequency noise spectrum regimes where different design criteria apply.......We experimentally demonstrate for a 28 Gbaud 64-QAM metro link that the LO frequency noise causes timing impairment. Results show the existence of LO frequency noise spectrum regimes where different design criteria apply....
Rimvall, M K; Clemmensen, L; Munkholm, A; Rask, C U; Larsen, J T; Skovgaard, A M; Simons, C J P; van Os, J; Jeppesen, P
2016-10-01
Auditory verbal hallucinations (AVH) are common during development and may arise due to dysregulation in top-down processing of sensory input. This study was designed to examine the frequency and correlates of speech illusions measured using the White Noise (WN) task in children from the general population. Associations between speech illusions and putative risk factors for psychotic disorder and negative affect were examined. A total of 1486 children aged 11-12 years of the Copenhagen Child Cohort 2000 were examined with the WN task. Psychotic experiences and negative affect were determined using the Kiddie-SADS-PL. Register data described family history of mental disorders. Exaggerated Theory of Mind functioning (hyper-ToM) was measured by the ToM Storybook Frederik. A total of 145 (10%) children experienced speech illusions (hearing speech in the absence of speech stimuli), of which 102 (70%) experienced illusions perceived by the child as positive or negative (affectively salient). Experiencing hallucinations during the last month was associated with affectively salient speech illusions in the WN task [general cognitive ability: adjusted odds ratio (aOR) 2.01, 95% confidence interval (CI) 1.03-3.93]. Negative affect, both last month and lifetime, was also associated with affectively salient speech illusions (aOR 2.01, 95% CI 1.05-3.83 and aOR 1.79, 95% CI 1.11-2.89, respectively). Speech illusions were not associated with delusions, hyper-ToM or family history of mental disorders. Speech illusions were elicited in typically developing children in a WN-test paradigm, and point to an affective pathway to AVH mediated by dysregulation in top-down processing of sensory input.
White noise from dark matter: 21 cm observations of early baryon collapse
International Nuclear Information System (INIS)
Zurek, Kathryn M.; Hogan, Craig J.
2007-01-01
In concordance cosmology, dark matter density perturbations generated by inflation lead to nonlinear, virialized minihalos, into which baryons collapse at redshift z∼20. We survey here novel baryon evolution produced by a modification of the power spectrum from white noise density perturbations at scales below k∼10h Mpc -1 (the smallest scales currently measured with the Lyman-α forest). Exotic dark matter dynamics, such as would arise from scalar dark matter with a late phase transition (similar to an axion, but with lower mass), or primordial black hole dark matter, create such an amplification of small scale power. The dark matter produced in such a phase transition collapses into minihalos, with a size given by the dark matter mass within the horizon at the phase transition. If the mass of the initial minihalos is larger than ∼10 -3 M · , the modified power spectrum is found to cause widespread baryon collapse earlier than standard ΛCDM, leading to earlier gas heating. It also results in higher spin temperature of the baryons in the 21 cm line relative to ΛCDM at redshifts z>20 if the mass of the minihalo is larger than 1M · . It is estimated that experiments probing 21 cm radiation at high redshift will contribute a significant constraint on dark matter models of this type for initial minihalos larger than ∼10M · . These experiments may also detect (or rule out) primordial black holes as the dark matter in the window 30M · H 3 M · still left open by strong microlensing experiments and other astrophysical constraints. Early experiments reaching to z≅15 will constrain minihalos down to ∼10 3 M ·
GÖKSOY, Cüneyt
2000-01-01
The evoked potential components in a time window of 10-50 ms following an acoustic stimulus are called middle latency responses (MLRs). It is known that an amplitude enlargement occurs in guinea pig MLRs to monaural clicks when continuous white noise is applied to the other ear. This study was undertaken to see whether this enlargement is due simply to an overall, generalised effect of contralateral white noise (WN), or whether it may have some connection to directional hearing. Re...
International Nuclear Information System (INIS)
Ichiki, Akihisa; Shiino, Masatoshi
2007-01-01
Effects of synaptic noise on the retrieval process of associative memory neural networks are studied from the viewpoint of neurobiological and biophysical understanding of information processing in the brain. We investigate the statistical mechanical properties of stochastic analogue neural networks with temporally fluctuating synaptic noise, which is assumed to be white noise. Such networks, in general, defy the use of the replica method, since they have no energy concept. The self-consistent signal-to-noise analysis (SCSNA), which is an alternative to the replica method for deriving a set of order parameter equations, requires no energy concept and thus becomes available in studying networks without energy functions. Applying the SCSNA to stochastic networks requires the knowledge of the Thouless-Anderson-Palmer (TAP) equation which defines the deterministic networks equivalent to the original stochastic ones. The study of the TAP equation which is of particular interest for the case without energy concept is very less, while it is closely related to the SCSNA in the case with energy concept. This paper aims to derive the TAP equation for networks with synaptic noise together with a set of order parameter equations by a hybrid use of the cavity method and the SCSNA
THE ELM SURVEY. II. TWELVE BINARY WHITE DWARF MERGER SYSTEMS
International Nuclear Information System (INIS)
Kilic, Mukremin; Brown, Warren R.; Kenyon, S. J.; Prieto, Carlos Allende; Agueeros, M. A.; Heinke, Craig
2011-01-01
We describe new radial velocity and X-ray observations of extremely low-mass white dwarfs (ELM WDs, ∼0.2 M sun ) in the Sloan Digital Sky Survey Data Release 4 and the MMT Hypervelocity Star survey. We identify four new short period binaries, including two merger systems. These observations bring the total number of short period binary systems identified in our survey to 20. No main-sequence or neutron star companions are visible in the available optical photometry, radio, and X-ray data. Thus, the companions are most likely WDs. Twelve of these systems will merge within a Hubble time due to gravitational wave radiation. We have now tripled the number of known merging WD systems. We discuss the characteristics of this merger sample and potential links to underluminous supernovae, extreme helium stars, AM CVn systems, and other merger products. We provide new observational tests of the WD mass-period distribution and cooling models for ELM WDs. We also find evidence for a new formation channel for single low-mass WDs through binary mergers of two lower mass objects.
Image processing methods for noise reduction in the TJ-II Thomson Scattering diagnostic
Energy Technology Data Exchange (ETDEWEB)
Dormido-Canto, S., E-mail: sebas@dia.uned.es [Departamento de Informatica y Automatica, UNED, Madrid 28040 (Spain); Farias, G. [Pontificia Universidad Catolica de Valparaiso, Valparaiso (Chile); Vega, J.; Pastor, I. [Asociacion EURATOM/CIEMAT para Fusion, Madrid 28040 (Spain)
2012-12-15
Highlights: Black-Right-Pointing-Pointer We describe an approach in order to reduce or mitigate the stray-light on the images and show the exceptional results. Black-Right-Pointing-Pointer We analyze the parameters to take account in the proposed process. Black-Right-Pointing-Pointer We report a simplified exampled in order to explain the proposed process. - Abstract: The Thomsom Scattering diagnostic of the TJ-II stellarator provides temperature and density profiles. The CCD camera acquires images corrupted with noise that, in some cases, can produce unreliable profiles. The main source of noise is the so-called stray-light. In this paper we describe an approach that allows mitigation of the effects that stray-light has on the images: extraction regions with connected-components. In addition, the robustness and effectiveness of the noise reduction technique is validated in two ways: (1) supervised classification and (2) comparison of electron temperature profiles.
Lin, Li-Wei; Weng, Shu-Chuan; Wu, Hua-Shan; Tsai, Lu-Jen; Lin, Ya-Ling; Yeh, Shu-Hui
2018-02-01
The aging of society is a global trend, and care of older adults with dementia is an urgent challenge. As dementia progresses, patients exhibit negative emotions, memory disorders, sleep disorders, and agitated behavior. Agitated behavior is one of the most difficult problems for family caregivers and healthcare providers to handle when caring for older adults with dementia. The aim of this study was to investigate the effectiveness of white noise in improving agitated behavior, mental status, and activities of daily living in older adults with dementia. An experimental research design was used to study elderly participants two times (pretest and posttest). Six dementia care centers in central and southern Taiwan were targeted to recruit participants. There were 63 participants: 28 were in the experimental group, and 35 were in the comparison group. Experimental group participants received 20 minutes of white noise consisting of ocean, rain, wind, and running water sounds between 4 and 5 P.M. daily over a period of 4 weeks. The comparison group received routine care. Questionnaires were completed, and observations of agitated behaviors were collected before and after the intervention. Agitated behavior in the experimental group improved significantly between pretest and posttest. Furthermore, posttest scores on the Mini-Mental Status Examination and Barthel Index were slightly better for this group than at pretest. However, the experimental group registered no significant difference in mental status or activities of daily living at posttest. For the comparison group, agitated behavior was unchanged between pretest and posttest. The results of this study support white noise as a simple, convenient, and noninvasive intervention that improves agitated behavior in older adults with dementia. These results may provide a reference for related healthcare providers, educators, and administrators who care for older adults with dementia.
Reddy, C. P.; Gupta, S. C.
1973-01-01
An all digital phase locked loop which tracks the phase of the incoming sinusoidal signal once per carrier cycle is proposed. The different elements and their functions and the phase lock operation are explained in detail. The nonlinear difference equations which govern the operation of the digital loop when the incoming signal is embedded in white Gaussian noise are derived, and a suitable model is specified. The performance of the digital loop is considered for the synchronization of a sinusoidal signal. For this, the noise term is suitably modelled which allows specification of the output probabilities for the two level quantizer in the loop at any given phase error. The loop filter considered increases the probability of proper phase correction. The phase error states in modulo two-pi forms a finite state Markov chain which enables the calculation of steady state probabilities, RMS phase error, transient response and mean time for cycle skipping.
Detecting modulated signals in modulated noise: (II) neural thresholds in the songbird forebrain.
Bee, Mark A; Buschermöhle, Michael; Klump, Georg M
2007-10-01
Sounds in the real world fluctuate in amplitude. The vertebrate auditory system exploits patterns of amplitude fluctuations to improve signal detection in noise. One experimental paradigm demonstrating these general effects has been used in psychophysical studies of 'comodulation detection difference' (CDD). The CDD effect refers to the fact that thresholds for detecting a modulated, narrowband noise signal are lower when the envelopes of flanking bands of modulated noise are comodulated with each other, but fluctuate independently of the signal compared with conditions in which the envelopes of the signal and flanking bands are all comodulated. Here, we report results from a study of the neural correlates of CDD in European starlings (Sturnus vulgaris). We manipulated: (i) the envelope correlations between a narrowband noise signal and a masker comprised of six flanking bands of noise; (ii) the signal onset delay relative to masker onset; (iii) signal duration; and (iv) masker spectrum level. Masked detection thresholds were determined from neural responses using signal detection theory. Across conditions, the magnitude of neural CDD ranged between 2 and 8 dB, which is similar to that reported in a companion psychophysical study of starlings [U. Langemann & G.M. Klump (2007) Eur. J. Neurosci., 26, 1969-1978]. We found little evidence to suggest that neural CDD resulted from the across-channel processing of auditory grouping cues related to common envelope fluctuations and synchronous onsets between the signal and flanking bands. We discuss a within-channel model of peripheral processing that explains many of our results.
Blasche, P. R.
1980-01-01
Specific configurations of first and second order all digital phase locked loops are analyzed for both ideal and additive white gaussian noise inputs. In addition, a design for a hardware digital phase locked loop capable of either first or second order operation is presented along with appropriate experimental data obtained from testing of the hardware loop. All parameters chosen for the analysis and the design of the digital phase locked loop are consistent with an application to an Omega navigation receiver although neither the analysis nor the design are limited to this application.
White organic light-emitting devices incorporating nanoparticles of II-VI semiconductors
International Nuclear Information System (INIS)
Ahn, Jin H; Bertoni, Cristina; Dunn, Steve; Wang, Changsheng; Talapin, Dmitri V; Gaponik, Nikolai; Eychmueller, Alexander; Hua Yulin; Bryce, Martin R; Petty, Michael C
2007-01-01
A blue-green fluorescent organic dye and red-emitting nanoparticles, based on II-VI semiconductors, have been used together in the fabrication of white organic light-emitting devices. In this work, the materials were combined in two different ways: in the form of a blend, and as separate layers deposited on the opposite sides of the substrate. The blended-layer structure provided purer white emission. However, this device also exhibited a number of disadvantages, namely a high drive voltage, a low efficiency and some colour instability. These problems could be avoided by using a device structure that was fabricated using separate dye and nanoparticle layers
International Nuclear Information System (INIS)
Saha, Surajit; Ganguly, Jayanta; Ghosh, Manas
2015-01-01
We make a rigorous exploration of the profiles of off-diagonal components of frequency-dependent linear (α xy , α yx ), first nonlinear (β xyy , β yxx ), and second nonlinear (γ xxyy , γ yyxx ) polarizabilities of quantum dots driven by Gaussian white noise. The quantum dot is doped with repulsive Gaussian impurity. Noise has been applied additively and multiplicatively to the system. An external oscillatory electric field has also been applied to the system. Gradual variations of external frequency, dopant location, and noise strength give rise to interesting features of polarizability components. The observations reveal intricate interplay between noise strength and dopant location which designs the polarizability profiles. Moreover, the mode of application of noise also modulates the polarizability components. Interestingly, in case of additive noise the noise strength has no role on polarizabilities whereas multiplicative noise invites greater delicacy in them. The said interplay provides a rather involved framework to attain stable, enhanced, and often maximized output of linear and nonlinear polarizabilities. - Highlights: • Linear and nonlinear polarizabilities of quantum dot are studied. • The polarizability components are off-diagonal and frequency-dependent. • Quantum dot is doped with a repulsive impurity. • Doped system is subject to Gaussian white noise. • Mode of noise application affects polarizabilities
Directory of Open Access Journals (Sweden)
Suzannah K Helps
Full Text Available Noise often has detrimental effects on performance. However, because of the phenomenon of stochastic resonance (SR, auditory white noise (WN can alter the "signal to noise" ratio and improve performance. The Moderate Brain Arousal (MBA model postulates different levels of internal "neural noise" in individuals with different attentional capacities. This in turn determines the particular WN level most beneficial in each individual case-with one level of WN facilitating poor attenders but hindering super-attentive children. The objective of the present study is to find out if added WN affects cognitive performance differently in children that differ in attention ability.Participants were teacher-rated super- (N = 25; normal- (N = 29 and sub-attentive (N = 36 children (aged 8 to 10 years. Two non-executive function (EF tasks (a verbal episodic recall task and a delayed verbal recognition task and two EF tasks (a visuo-spatial working memory test and a Go-NoGo task were performed under three WN levels. The non-WN condition was only used to control for potential differences in background noise in the group testing situations.There were different effects of WN on performance in the three groups-adding moderate WN worsened the performance of super-attentive children for both task types and improved EF performance in sub-attentive children. The normal-attentive children's performance was unaffected by WN exposure. The shift from moderate to high levels of WN had little further effect on performance in any group.The predicted differential effect of WN on performance was confirmed. However, the failure to find evidence for an inverted U function challenges current theories. Alternative explanations are discussed. We propose that WN therapy should be further investigated as a possible non-pharmacological treatment for inattention.
Helps, Suzannah K; Bamford, Susan; Sonuga-Barke, Edmund J S; Söderlund, Göran B W
2014-01-01
Noise often has detrimental effects on performance. However, because of the phenomenon of stochastic resonance (SR), auditory white noise (WN) can alter the "signal to noise" ratio and improve performance. The Moderate Brain Arousal (MBA) model postulates different levels of internal "neural noise" in individuals with different attentional capacities. This in turn determines the particular WN level most beneficial in each individual case-with one level of WN facilitating poor attenders but hindering super-attentive children. The objective of the present study is to find out if added WN affects cognitive performance differently in children that differ in attention ability. Participants were teacher-rated super- (N = 25); normal- (N = 29) and sub-attentive (N = 36) children (aged 8 to 10 years). Two non-executive function (EF) tasks (a verbal episodic recall task and a delayed verbal recognition task) and two EF tasks (a visuo-spatial working memory test and a Go-NoGo task) were performed under three WN levels. The non-WN condition was only used to control for potential differences in background noise in the group testing situations. There were different effects of WN on performance in the three groups-adding moderate WN worsened the performance of super-attentive children for both task types and improved EF performance in sub-attentive children. The normal-attentive children's performance was unaffected by WN exposure. The shift from moderate to high levels of WN had little further effect on performance in any group. The predicted differential effect of WN on performance was confirmed. However, the failure to find evidence for an inverted U function challenges current theories. Alternative explanations are discussed. We propose that WN therapy should be further investigated as a possible non-pharmacological treatment for inattention.
Thompson, William F.; Kuske, Rachel A.; Monahan, Adam H.
2017-11-01
Stochastic averaging problems with Gaussian forcing have been the subject of numerous studies, but far less attention has been paid to problems with infinite-variance stochastic forcing, such as an α-stable noise process. It has been shown that simple linear systems driven by correlated additive and multiplicative (CAM) Gaussian noise, which emerge in the context of reduced atmosphere and ocean dynamics, have infinite variance in certain parameter regimes. In this study, we consider the stochastic averaging of systems where a linear CAM noise process in the infinite variance parameter regime drives a comparatively slow process. We use (semi)-analytical approximations combined with numerical illustrations to compare the averaged process to one that is forced by a white α-stable process, demonstrating consistent properties in the case of large time-scale separation. We identify the conditions required for the fast linear CAM process to have such an influence in driving a slower process and then derive an (effectively) equivalent fast, infinite-variance process for which an existing stochastic averaging approximation is readily applied. The results are illustrated using numerical simulations of a set of example systems.
Olatunji, Bunmi O; Sawchuk, Craig N; Lee, Thomas C; Lohr, Jeffrey M; Tolin, David F
2008-06-01
The present study examines attentional and implicit memory biases in spider phobic and nonphobic participants. The results showed that spider phobics demonstrated increased interference for neutral, negative, and spider-relevant words on a computerized Stroop task. However, no group differences emerged when adjusting for differences in color-naming speed. Prior exposure to a dead spider did result in higher overall Stroop interference in spider phobics and this appeared to be mostly pronounced for spider-relevant words. Implicit memory bias for threat was examined with a noise judgment task. Participants first heard neutral and spider-relevant sentences and implicit memory for these sentences was evaluated by having participants rate the volume of noise accompanying the presentation of old sentences intermixed with new sentences. An implicit memory bias is indicated if participants rate noise accompanying old sentences as less loud than noise accompanying new sentences. No evidence was found for an implicit memory bias in spider phobics. These findings are discussed in relation to the role of information processing biases in spider phobia.
The effectiveness of correcting codes in reception in the whole in additive normal white noise
Shtarkov, Y. M.
1974-01-01
Some possible criteria for estimating the effectiveness of correcting codes are presented, and the energy effectiveness of correcting codes is studied for symbol-by-symbol reception. Expressions for the energetic effectiveness of binary correcting codes for reception in the whole are produced. Asymptotic energetic effectiveness and finite signal/noise ratio cases are considered.
Xie, Bin
2018-01-01
In this paper, the main topic is to investigate the intermittent property of the one-dimensional stochastic heat equation driven by an inhomogeneous Brownian sheet, which is a noise deduced from the study of the catalytic super-Brownian motion. Under some proper conditions on the catalytic measure of the inhomogeneous Brownian sheet, we show that the solution is weakly full intermittent based on the estimates of moments of the solution. In particular, it is proved that the second moment of the solution grows at the exponential rate. The novelty is that the catalytic measure relative to the inhomogeneous noise is not required to be absolutely continuous with respect to the Lebesgue measure on R.
International Nuclear Information System (INIS)
Accardi, Luigi; Boukas, Andreas
2008-01-01
The identification of the *-Lie algebra of the renormalized higher powers of White noise (RHPWN) and the analytic continuation of the second quantized centreless Virasoro (or Witt)-Zamolodchikov-w ∞ *-Lie algebra of conformal field theory and high-energy physics, was recently established on results obtained. In the present paper, we show how the RHPWN Fock kernels must be truncated in order to be positive semi-definite and we obtain a Fock representation of the two algebras. We show that the truncated renormalized higher powers of White noise (TRHPWN) Fock spaces of order ≥2 host the continuous binomial and beta processes
Living in a simulacrum: how TV and the supermarket redefines reality in Don DeLillo’s White Noise
Directory of Open Access Journals (Sweden)
Ghashmari, Ahmad
2010-07-01
Full Text Available This paper examines the impact of simulation, hyperreality, and consumerism on Don Delillo's novel "White Noise". It discusses how the novel pictures technology and mass media as an empire of signs and codes that erase or implode meaning. TV, radio reports and tidbits, and medical imaging devices are intertwined with many aspects of people's lives in this late capitalist culture. Futhermore, the paper will shed some light on the issue of hyperreality which is generated by simulations. We will see how this new type of reality becomes more real than reality itself. Then, the influence of the supermarket and the emergence of consumer culture will be discussed. We will see how production and consumption have gained a new different meaning in this new "superficial" society and how it reshapes people's undestanding and interaction with reality.
Johnson, E. H.
1975-01-01
The optimal design was investigated of simple structures subjected to dynamic loads, with constraints on the structures' responses. Optimal designs were examined for one dimensional structures excited by harmonically oscillating loads, similar structures excited by white noise, and a wing in the presence of continuous atmospheric turbulence. The first has constraints on the maximum allowable stress while the last two place bounds on the probability of failure of the structure. Approximations were made to replace the time parameter with a frequency parameter. For the first problem, this involved the steady state response, and in the remaining cases, power spectral techniques were employed to find the root mean square values of the responses. Optimal solutions were found by using computer algorithms which combined finite elements methods with optimization techniques based on mathematical programming. It was found that the inertial loads for these dynamic problems result in optimal structures that are radically different from those obtained for structures loaded statically by forces of comparable magnitude.
Hamid, Ka; Yusoff, An; Rahman, Mza; Mohamad, M; Hamid, Aia
2012-04-01
This fMRI study is about modelling the effective connectivity between Heschl's gyrus (HG) and the superior temporal gyrus (STG) in human primary auditory cortices. MATERIALS #ENTITYSTARTX00026; Ten healthy male participants were required to listen to white noise stimuli during functional magnetic resonance imaging (fMRI) scans. Statistical parametric mapping (SPM) was used to generate individual and group brain activation maps. For input region determination, two intrinsic connectivity models comprising bilateral HG and STG were constructed using dynamic causal modelling (DCM). The models were estimated and inferred using DCM while Bayesian Model Selection (BMS) for group studies was used for model comparison and selection. Based on the winning model, six linear and six non-linear causal models were derived and were again estimated, inferred, and compared to obtain a model that best represents the effective connectivity between HG and the STG, balancing accuracy and complexity. Group results indicated significant asymmetrical activation (p(uncorr) Model comparison results showed strong evidence of STG as the input centre. The winning model is preferred by 6 out of 10 participants. The results were supported by BMS results for group studies with the expected posterior probability, r = 0.7830 and exceedance probability, ϕ = 0.9823. One-sample t-tests performed on connection values obtained from the winning model indicated that the valid connections for the winning model are the unidirectional parallel connections from STG to bilateral HG (p model comparison between linear and non-linear models using BMS prefers non-linear connection (r = 0.9160, ϕ = 1.000) from which the connectivity between STG and the ipsi- and contralateral HG is gated by the activity in STG itself. We are able to demonstrate that the effective connectivity between HG and STG while listening to white noise for the respective participants can be explained by a non-linear dynamic causal model with
Energy Technology Data Exchange (ETDEWEB)
Xiao, Yanwen; Xu, Wei, E-mail: weixu@nwpu.edu.cn; Wang, Liang [Department of Applied Mathematics, Northwestern Polytechnical University, Xi' an 710072 (China)
2016-03-15
This paper focuses on the study of the stochastic Van der Pol vibro-impact system with fractional derivative damping under Gaussian white noise excitation. The equations of the original system are simplified by non-smooth transformation. For the simplified equation, the stochastic averaging approach is applied to solve it. Then, the fractional derivative damping term is facilitated by a numerical scheme, therewith the fourth-order Runge-Kutta method is used to obtain the numerical results. And the numerical simulation results fit the analytical solutions. Therefore, the proposed analytical means to study this system are proved to be feasible. In this context, the effects on the response stationary probability density functions (PDFs) caused by noise excitation, restitution condition, and fractional derivative damping are considered, in addition the stochastic P-bifurcation is also explored in this paper through varying the value of the coefficient of fractional derivative damping and the restitution coefficient. These system parameters not only influence the response PDFs of this system but also can cause the stochastic P-bifurcation.
Xiao, Yanwen; Xu, Wei; Wang, Liang
2016-03-01
This paper focuses on the study of the stochastic Van der Pol vibro-impact system with fractional derivative damping under Gaussian white noise excitation. The equations of the original system are simplified by non-smooth transformation. For the simplified equation, the stochastic averaging approach is applied to solve it. Then, the fractional derivative damping term is facilitated by a numerical scheme, therewith the fourth-order Runge-Kutta method is used to obtain the numerical results. And the numerical simulation results fit the analytical solutions. Therefore, the proposed analytical means to study this system are proved to be feasible. In this context, the effects on the response stationary probability density functions (PDFs) caused by noise excitation, restitution condition, and fractional derivative damping are considered, in addition the stochastic P-bifurcation is also explored in this paper through varying the value of the coefficient of fractional derivative damping and the restitution coefficient. These system parameters not only influence the response PDFs of this system but also can cause the stochastic P-bifurcation.
DEFF Research Database (Denmark)
Micaletti, R. C.; Cakmak, A. S.; Nielsen, Søren R. K.
Differential equations are derived which exactly govern the evolution of the second-order response moments of a single-degree-of-freedom (SDOF) bilinear hysteretic oscillator subject to stationary Gaussian white noise excitation. Then, considering cases for which response stationarity...
International Nuclear Information System (INIS)
Botelho, Luiz C.L.
2004-01-01
We analyze the triviality-quantum decoherence of Euclidean quantum chromodynamics in the gauge invariant quark current sector in the presence of a very strong external white-noise electromagnetic (strength) field within the context of QCD in the 't Hooft limit of a large number of colors
Performance of peaky template matching under additive white Gaussian noise and uniform quantization
Horvath, Matthew S.; Rigling, Brian D.
2015-05-01
Peaky template matching (PTM) is a special case of a general algorithm known as multinomial pattern matching originally developed for automatic target recognition of synthetic aperture radar data. The algorithm is a model- based approach that first quantizes pixel values into Nq = 2 discrete values yielding generative Beta-Bernoulli models as class-conditional templates. Here, we consider the case of classification of target chips in AWGN and develop approximations to image-to-template classification performance as a function of the noise power. We focus specifically on the case of a uniform quantization" scheme, where a fixed number of the largest pixels are quantized high as opposed to using a fixed threshold. This quantization method reduces sensitivity to the scaling of pixel intensities and quantization in general reduces sensitivity to various nuisance parameters difficult to account for a priori. Our performance expressions are verified using forward-looking infrared imagery from the Army Research Laboratory Comanche dataset.
Xu, Chang
2017-04-01
The intrinsic random variability of an astronomical source hampers the detection of possible periodicities that we are interested in. We find that a simple first-order autoregressive [AR(1)] process gives a poor fit to the power decay in the observed spectrum for astrophysical sources and geodetic observations. Thus, appropriate background noise models have to be chosen for significance tests to distinguish real features from the intrinsic variability of the source. Here we recall the wavelet analysis with significance and confidence testing but extend it with the generalized Gauss Markov stochastic model as the null hypothesis, which includes AR(1) and a power law as special cases. We exemplify this discussion with real data, such as sunspot number data, geomagnetic indices, X-ray observations, as well as a Global Positioning System (GPS) position time series.
International Nuclear Information System (INIS)
Greef, C.P.
1978-03-01
The current state of power reactor noise analysis as presented at the Second Specialists' Meeting on Reactor Noise (SMORN II) is reviewed. Practical successes include the analysis of PWR core support barrel motions and BWR instrument tube vibrations, leading to better understanding of the Physical processes involved. Future applications to LMFBRs are being actively pursued, but more information is required, notably on background noise sources in operating reactors. Theoretical understanding is improving in a number of specific areas, but general fundamental progress is hampered by the multiplicity of potential noise sources in a reactor. Past attempts to automate noise analysis so that simplified information may be presented to the reactor operator have not been totally successful. This has resulted from an over-hasty application of the techniques before all of the factors involved in physical phenomena were fully appreciated. (author)
Advance Noise Control Fan II: Test Rig Fan Risk Management Study
Lucero, John
2013-01-01
Since 1995 the Advanced Noise Control Fan (ANCF) has significantly contributed to the advancement of the understanding of the physics of fan tonal noise generation. The 9'x15' WT has successfully tested multiple high speed fan designs over the last several decades. This advanced several tone noise reduction concepts to higher TRL and the validation of fan tone noise prediction codes.
Kearns, Nicholas M; Mehlenbacher, Randy D; Jones, Andrew C; Zanni, Martin T
2017-04-03
We have developed a broad bandwidth two-dimensional electronic spectrometer that operates shot-to-shot at repetition rates up to 100 kHz using an acousto-optic pulse shaper. It is called a two-dimensional white-light (2D-WL) spectrometer because the input is white-light supercontinuum. Methods for 100 kHz data collection are studied to understand how laser noise is incorporated into 2D spectra during measurement. At 100 kHz, shot-to-shot scanning of the delays and phases of the pulses in the pulse sequence produces a 2D spectrum 13-times faster and with the same signal-to-noise as using mechanical stages and a chopper. Comparing 100 to 1 kHz repetition rates, data acquisition time is decreased by a factor of 200, which is beyond the improvement expected by the repetition rates alone due to reduction in 1/f noise. These improvements arise because shot-to-shot readout and modulation of the pulse train at 100 kHz enables the electronic coherences to be measured faster than the decay in correlation between laser intensities. Using white light supercontinuum for the pump and probe pulses produces high signal-to-noise spectra on samples with optical densities 200 nm bandwidth.
Riga, Maria; Komis, Agis; Marangoudakis, Pavlos; Naxakis, Stefanos; Ferekidis, Eleftherios; Kandiloros, Dimitrios; Danielides, Vasilios
2017-08-01
The mechanisms underlying the shift from acute tinnitus to chronic remain obscure. An association between tinnitus and medial olivocochlear bundle (MOCB) reflex dysfunction has been hypothesised by several studies. The differences between participants with acute and chronic tinnitus have not yet been investigated. Participants were examined with distortion product otoacoustic emissions (DPOAEs) suppression elicited by contralateral white noise. They were compared in terms of frequency regions with non-recordable DPOAEs, suppression amplitudes and the presence of DPOAE enhancement. Eighteen participants with acute tinnitus, 40 age-matched adults with chronic tinnitus and 17 controls were included. All participants (aged 34.7 ± 9.6years; mean ± Standard deviation) had normal hearing. Tinnitus was bilateral in 22 participants and unilateral in 36. Ears with chronic tinnitus presented significantly lower DPOAE suppression amplitudes than ears with acute tinnitus (p tinnitus ears present a high prevalence of enhancement, significantly different from controls (p tinnitus and control groups (p tinnitus becomes chronic, DPOAEs suppression presents changes that might reveal corresponding steps in tinnitus pathophysiology. Treatment implications are discussed.
Riga, M; Komis, A; Maragkoudakis, P; Korres, G; Danielides, V
2016-12-01
Normative otoacoustic emission (OAE) suppression values are currently lacking and the role of cochlear efferent innervation in tinnitus is controversial. The aim of this study was to investigate the association between tinnitus and medial olivocochlear bundle (MOCB) malfunction. Potential suppression amplitude cut-off criteria that could differentiate participants with tinnitus from those without were sought. Mean suppression amplitudes of transient evoked OAEs and distortion product OAEs by contralateral white noise (50 dBSL) were recorded. Six mean suppression amplitudes criteria were validated as possible cut-off points. The population consisted of normal hearing (n = 78) or presbycusic adults (n = 19) with tinnitus or without (n = 28 and 13, respectively) chronic tinnitus (in total, n = 138 78 females/60males, aged 49 ± 14 years). Participants with mean suppression values lower than 0.5-1 dBSPL seem to present a high probability to report tinnitus (specificity 88-97%). On the other hand, participants with mean suppression values larger than 2-2.5dBSPL seem to present a high probability of the absence of tinnitus (sensitivity 87-99%). Correlations were stronger among participants with bilateral presence or absence of tinnitus. This study seem to confirm an association between tinnitus and low suppression amplitudes (<1 dBSPL), which might evolve into an objective examination tool, supplementary to conventional audiological testing.
International Nuclear Information System (INIS)
Bonnarme, P.; Jeffries, T.W.
1990-01-01
Two families of peroxidases-lignin peroxidase (LiP) and manganese-dependent lignin peroxidase (MnP)-are formed by the lignin-degrading white rot basidiomycete Phanerochaete chrysosporium and other white rot fungi. Isoenzymes of these enzyme families carry out reactions important to the biodegradation of lignin. This research investigated the regulation of LiP and MnP production by Mn(II). In liquid culture, LiP titers varied as an inverse function of and MnP titers varied as a direct function of the Mn(II) concentration. The extracellular isoenzyme profiles differed radically at low and high Mn(II) levels, whereas other fermentation parameters, including extracellular protein concentrations, the glucose consumption rate, and the accumulation of cell dry weight, did not change significantly with the Mn(II) concentration. In the absence of Mn(II), extracellular LiP isoenzymes predominated, whereas in the presence of Mn(II), MnP isoenzymes were dominant. The release of 14 CO 2 from 14 C-labeled dehydrogenative polymerizate lignin was likewise affected by Mn(II). The rate of 14 CO 2 release increased at low Mn(II) and decreased at high Mn(II) concentrations. This regulatory effect of Mn(II) occurred with five strains of P. chrysosporium, two other species of Phanerochaete, three species of Phlebia, Lentinula edodes, and Phellinus pini
Background- and simulated leak-noise measurements on ASB-loop, KNK II- and SNR 300-steam generators
International Nuclear Information System (INIS)
Voss, J.; Arnaoutis, N.; Foerster, K.; Moellerfeld, H.
1990-01-01
During several leak propagation experiments in the ASB sodium loop noise measurements were performed showing the acoustic behaviour of evoluting leaks in a tube bundle section under sodium. Effects like self evolution, secondary leaks and tube ruptures by overheating occurred during these tests and were reflected in the course of acoustic signals. In one of the KNK II steam generators simulated leak noise was detected against background noise throughout the operating power range. Experimental arrangements and results are described. In SNR 300 all of the SGUs are equipped with waveguides and some with accelerometers for background noise measurements. First measurement under isothermal conditions were performed in the past. A gas injection device for acoustic leak simulation is under construction. The design of the experimental acoustic system and first results are presented. (author). 1 ref., 21 figs, 2 tabs
Salehi, Mohammad Saied; Namavar, Mohammad Reza; Tamadon, Amin; Bahmani, Raziyeh; Jafarzadeh Shirazi, Mohammad Reza; Khazali, Homayoun; Dargahi, Leila; Pandamooz, Sareh; Mohammad-Rezazadeh, Farzad; Rashidi, Fatemeh Sadat
2017-01-01
To evaluate the effects of long-term, moderate level noise exposure during crucial periods of rat infants on stereological parameters of medial geniculate body (MGB) and auditory cortex. Twenty-four male offspring of 12 pregnant rats were divided into four groups: fetal-to-critical period group, which were exposed to noise from the last 10 days of fetal life till postnatal day (PND) 29; fetal period group that exposed to noise during the last 10 days of fetal life; critical period group, exposed to noise from PND 15 till PND 29, and control group. White noise at 90 dB for 2 h per day was used. Variance for variables was performed using Proc GLM followed by mean comparison by Duncan's multiple range test. Numerical density of neurons in MGB of fetal-to-critical period group was lower than control group. Similar results were seen in numerical density of neurons in layers IV and VI of auditory cortex. Furthermore, no significant difference was observed in the volume of auditory cortex among groups, and only MGB volume in fetal-to-critical period group was higher than other groups. Estimated total number of neurons in MGB was not significantly different among groups. It seems necessary to prevent long-term moderate level noise exposure during fetal-to-critical neonatal period.
Krysko, V. A.; Awrejcewicz, J.; Krylova, E. Yu; Papkova, I. V.; Krysko, A. V.
2018-06-01
Parametric non-linear vibrations of flexible cylindrical panels subjected to additive white noise are studied. The governing Marguerre equations are investigated using the finite difference method (FDM) of the second-order accuracy and the Runge-Kutta method. The considered mechanical structural member is treated as a system of many/infinite number of degrees of freedom (DoF). The dependence of chaotic vibrations on the number of DoFs is investigated. Reliability of results is guaranteed by comparing the results obtained using two qualitatively different methods to reduce the problem of PDEs (partial differential equations) to ODEs (ordinary differential equations), i.e. the Faedo-Galerkin method in higher approximations and the 4th and 6th order FDM. The Cauchy problem obtained by the FDM is eventually solved using the 4th-order Runge-Kutta methods. The numerical experiment yielded, for a certain set of parameters, the non-symmetric vibration modes/forms with and without white noise. In particular, it has been illustrated and discussed that action of white noise on chaotic vibrations implies quasi-periodicity, whereas the previously non-symmetric vibration modes are closer to symmetric ones.
Kastelein, Ronald A; Wensveen, Paul J; Hoek, Lean; Au, Whitlow W L; Terhune, John M; de Jong, Christ A F
2009-09-01
A psychoacoustic behavioral technique was used to determine the critical ratios (CRs) of two harbor porpoises for tonal signals with frequencies between 0.315 and 150 kHz, in random Gaussian white noise. The masked 50% detection hearing thresholds were measured using a "go/no-go" response paradigm and an up-down staircase psychometric method. CRs were determined at one masking noise level for each test frequency and were similar in both animals. For signals between 0.315 and 4 kHz, the CRs were relatively constant at around 18 dB. Between 4 and 150 kHz the CR increased gradually from 18 to 39 dB ( approximately 3.3 dB/octave). Generally harbor porpoises can detect tonal signals in Gaussian white noise slightly better than most odontocetes tested so far. By combining the mean CRs found in the present study with the spectrum level of the background noise levels at sea, the basic audiogram, and the directivity index, the detection threshold levels of harbor porpoises for tonal signals in various sea states can be calculated.
Active noise control in a duct to cancel broadband noise
Chen, Kuan-Chun; Chang, Cheng-Yuan; Kuo, Sen M.
2017-09-01
The paper presents cancelling duct noises by using the active noise control (ANC) techniques. We use the single channel feed forward algorithm with feedback neutralization to realize ANC. Several kinds of ducts noises including tonal noises, sweep tonal signals, and white noise had investigated. Experimental results show that the proposed ANC system can cancel these noises in a PVC duct very well. The noise reduction of white noise can be up to 20 dB.
Durbin, P. A.
1983-01-01
It is shown how a high frequency analysis can be made for general problems involving flow-generated noise. In the parallel shear flow problem treated by Balsa (1976) and Goldstein (1982), the equation governing sound propagation in the moving medium could be transformed into a wave equation for a stationary medium with an inhomogeneous index of refraction. It is noted that the procedure of Avila and Keller (1963) was then used to construct a high frequency Green function. This procedure involves matching a solution valid in an inner region around the point source to an outer, ray-acoustics solution. This same procedure is used here to construct the Green function for a source in an arbitrary mean flow. In view of the fact that there is no restriction to parallel flow, the governing equations cannot be transformed into a wave equation; the analysis therefore proceeds from the equations of motion themselves.
Morisaki, Soichiro; Yokoyama, Jun'ichi; Eda, Kazunari; Itoh, Yousuke
2016-01-01
We introduce a new analysis method to deal with stationary non-Gaussian noises in gravitational wave detectors in terms of the independent component analysis. First, we consider the simplest case where the detector outputs are linear combinations of the inputs, consisting of signals and various noises, and show that this method may be helpful to increase the signal-to-noise ratio. Next, we take into account the time delay between the inputs and the outputs. Finally, we extend our method to nonlinearly correlated noises and show that our method can identify the coupling coefficients and remove non-Gaussian noises. Although we focus on gravitational wave data analysis, our methods are applicable to the detection of any signals under non-Gaussian noises.
Kohjiro, Satoshi; Hirayama, Fuminori; Yamamori, Hirotake; Nagasawa, Shuichi; Fukuda, Daiji; Hidaka, Mutsuo
2014-06-01
White noise of dissipationless microwave radio frequency superconducting quantum interference device (RF-SQUID) multiplexers has been experimentally studied to evaluate their readout performance for transition edge sensor (TES) photon counters ranging from near infrared to gamma ray. The characterization has been carried out at 4 K, first to avoid the low-frequency fluctuations present at around 0.1 K, and second, for a feasibility study of readout operation at 4 K for extended applications. To increase the resonant Q at 4 K and maintain low noise SQUID operation, multiplexer chips consisting of niobium nitride (NbN)-based coplanar-waveguide resonators and niobium (Nb)-based RF-SQUIDs have been developed. This hybrid multiplexer exhibited 1 × 104 ≤ Q ≤ 2 × 104 and the square root of spectral density of current noise referred to the SQUID input √SI = 31 pA/√Hz. The former and the latter are factor-of-five and seven improvements from our previous results on Nb-based resonators, respectively. Two-directional readout on the complex plane of the transmission component of scattering matrix S21 enables us to distinguish the flux noise from noise originating from other sources, such as the cryogenic high electron mobility transistor (HEMT) amplifier. Systematic noise measurements with various microwave readout powers PMR make it possible to distinguish the contribution of noise sources within the system as follows: (1) The achieved √SI is dominated by the Nyquist noise from a resistor at 4 K in parallel to the SQUID input coil which is present to prevent microwave leakage to the TES. (2) The next dominant source is either the HEMT-amplifier noise (for small values of PMR) or the quantization noise due to the resolution of 300-K electronics (for large values of PMR). By a decrease of these noise levels to a degree that is achievable by current technology, we predict that the microwave RF-SQUID multiplexer can exhibit √SI ≤ 5 pA/√Hz, i.e., close to √SI of
International Nuclear Information System (INIS)
Kohjiro, Satoshi; Hirayama, Fuminori; Yamamori, Hirotake; Nagasawa, Shuichi; Fukuda, Daiji; Hidaka, Mutsuo
2014-01-01
White noise of dissipationless microwave radio frequency superconducting quantum interference device (RF-SQUID) multiplexers has been experimentally studied to evaluate their readout performance for transition edge sensor (TES) photon counters ranging from near infrared to gamma ray. The characterization has been carried out at 4 K, first to avoid the low-frequency fluctuations present at around 0.1 K, and second, for a feasibility study of readout operation at 4 K for extended applications. To increase the resonant Q at 4 K and maintain low noise SQUID operation, multiplexer chips consisting of niobium nitride (NbN)-based coplanar-waveguide resonators and niobium (Nb)-based RF-SQUIDs have been developed. This hybrid multiplexer exhibited 1 × 10 4 ≤ Q ≤ 2 × 10 4 and the square root of spectral density of current noise referred to the SQUID input √S I = 31 pA/√Hz. The former and the latter are factor-of-five and seven improvements from our previous results on Nb-based resonators, respectively. Two-directional readout on the complex plane of the transmission component of scattering matrix S 21 enables us to distinguish the flux noise from noise originating from other sources, such as the cryogenic high electron mobility transistor (HEMT) amplifier. Systematic noise measurements with various microwave readout powers P MR make it possible to distinguish the contribution of noise sources within the system as follows: (1) The achieved √S I is dominated by the Nyquist noise from a resistor at 4 K in parallel to the SQUID input coil which is present to prevent microwave leakage to the TES. (2) The next dominant source is either the HEMT-amplifier noise (for small values of P MR ) or the quantization noise due to the resolution of 300-K electronics (for large values of P MR ). By a decrease of these noise levels to a degree that is achievable by current technology, we predict that the microwave RF-SQUID multiplexer can exhibit
Xu, Jinghong; Yu, Liping; Cai, Rui; Zhang, Jiping; Sun, Xinde
2010-04-01
Sensory experiences have important roles in the functional development of the mammalian auditory cortex. Here, we show how early continuous noise rearing influences spatial sensitivity in the rat primary auditory cortex (A1) and its underlying mechanisms. By rearing infant rat pups under conditions of continuous, moderate level white noise, we found that noise rearing markedly attenuated the spatial sensitivity of A1 neurons. Compared with rats reared under normal conditions, spike counts of A1 neurons were more poorly modulated by changes in stimulus location, and their preferred locations were distributed over a larger area. We further show that early continuous noise rearing induced significant decreases in glutamic acid decarboxylase 65 and gamma-aminobutyric acid (GABA)(A) receptor alpha1 subunit expression, and an increase in GABA(A) receptor alpha3 expression, which indicates a returned to the juvenile form of GABA(A) receptor, with no effect on the expression of N-methyl-D-aspartate receptors. These observations indicate that noise rearing has powerful adverse effects on the maturation of cortical GABAergic inhibition, which might be responsible for the reduced spatial sensitivity.
High Temperature Smart Structures for Engine Noise Reduction and Performance Enhancement, Phase II
National Aeronautics and Space Administration — Noise mitigation for subsonic transports is a continuing high priority, and recent work has identified successful exhaust mixing enhancement devices (chevrons) that...
International Nuclear Information System (INIS)
Fulinski, A.
1994-01-01
The properties of non-Markovian noises with exponentially correlated memory are discussed. Considered are dichotomic noise, white shot noise, Gaussian white noise, and Gaussian colored noise. The stationary correlation functions of the non-Markovian versions of these noises are given by linear combinations of two or three exponential functions (colored noises) or of the δ function and exponential function (white noises). The non-Markovian white noises are well defined only when the kernel of the non-Markovian master equation contains a nonzero admixture of a Markovian term. Approximate equations governing the probability densities for processes driven by such non-Markovian noises are derived, including non-Markovian versions of the Fokker-Planck equation and the telegrapher's equation. As an example, it is shown how the non-Markovian nature changes the behavior of the driven linear process
Development of a technique for inflight jet noise simulation. I, II
Clapper, W. S.; Stringas, E. J.; Mani, R.; Banerian, G.
1976-01-01
Several possible noise simulation techniques were evaluated, including closed circuit wind tunnels, free jets, rocket sleds and high speed trains. The free jet technique was selected for demonstration and verification. The first paper describes the selection and development of the technique and presents results for simulation and in-flight tests of the Learjet, F106, and Bertin Aerotrain. The second presents a theoretical study relating the two sets of noise signatures. It is concluded that the free jet simulation technique provides a satisfactory assessment of in-flight noise.
Koyuncu, Hasan; Ceylan, Rahime
2018-04-01
Dynamic Contrast-Enhanced Computed Tomography (DCE-CT) is applied to observe adrenal tumours in detail by utilising from the contrast matter, which generally brings the tumour into the forefront. However, DCE-CT images are generally influenced by noises that occur as the result of the trade-off between radiation doses vs. noise. Herein, this situation constitutes a challenge in the achievement of accurate tumour segmentation. In CT images, most of the noises are similar to Gaussian Noise. In this study, arterial phase CT images containing adrenal tumours are utilised, and elimination of Gaussian Noise is realised by fourteen different techniques reported in literature for the achievement of the best denoising process. In this study, the Block Matching and 3D Filtering (BM3D) algorithm typically achieve reliable Peak Signal-to-Noise Ratios (PSNR) and resolves challenges of similar techniques when addressing different levels of noise. Furthermore, BM3D obtains the best mean PSNR values among the first five techniques. BM3D outperforms to other techniques by obtaining better Total Statistical Success (TSS), CPU time and computation cost. Consequently, it prepares clearer arterial phase CT images for the next step (segmentation of adrenal tumours). Copyright © 2017 Elsevier Ltd. All rights reserved.
High Order Wavelet-Based Multiresolution Technology for Airframe Noise Prediction, Phase II
National Aeronautics and Space Administration — We propose to develop a novel, high-accuracy, high-fidelity, multiresolution (MRES), wavelet-based framework for efficient prediction of airframe noise sources and...
Chan, T.
2016-12-01
The Hong Kong International Airport (HKIA) handles a large amount of air traffic, at 68.5 million passengers per year (approx. 40.1 million flights per year). Given that flight demand is forecast to reach 97 million passengers per year (approx 60.2 million flights per year) by 2030, the HKIA must optimise runway capacity in order to meet growing demand. Hence, the Airport Authority Hong Kong (AAHK) has put forward a proposal to expand the airport into a three-runway system by building a third runway. However, this presents many environmental constraints. These include major impacts on marine ecology; especially the Chinese White Dolphins (Sousa chinensis) that live around the Sha Chau and Lung Kwu Chau Marine Park north to the airport. Due to that the third runway will reclaim approximately 650 hectares of the se so re-routing of speed boats and ferries has been planned. This includes one route that passes through the marine nursery inside the park. This indirectly causes noise pollution that will affect marine life. Since dolphins rely on echolocation (often discerned by a "click" sound) to communicate and navigate, increasing marine traffic (re-routing) causes obscuring noises and acoustic communication interfering with echolocation, as well as collisions which lead to physical injuries. Underwater construction works involving techniques such as percussive piling may interfere with the dolphins' echolocation capability. The data has been collected using a hydrophone by observing the noise frequency changes within the marine park. The noises come from a number of sources, including fishing boats, and speed boats, krill and around 20 estuarine fish species. The evaluation of four years (2013-2016) has shown that noise pollution is increasing (as indicated by the increase of frequencies around 100 125 kHz) and that it has caused disruption in regular dolphin movement (irregular clicking sequence) .
Derryberry, Elizabeth P; Gentry, Katherine; Derryberry, Graham E; Phillips, Jennifer N; Danner, Raymond M; Danner, Julie E; Luther, David A
2017-07-01
The soundscape acts as a selective agent on organisms that use acoustic signals to communicate. A number of studies document variation in structure, amplitude, or timing of signal production in correspondence with environmental noise levels thus supporting the hypothesis that organisms are changing their signaling behaviors to avoid masking. The time scale at which organisms respond is of particular interest. Signal structure may evolve across generations through processes such as cultural or genetic transmission. Individuals may also change their behavior during development (ontogenetic change) or in real time (i.e., immediate flexibility). These are not mutually exclusive mechanisms, and all must be investigated to understand how organisms respond to selection pressures from the soundscape. Previous work on white-crowned sparrows ( Zonotrichia leucophrys ) found that males holding territories in louder areas tend to sing higher frequency songs and that both noise levels and song frequency have increased over time (30 years) in urban areas. These previous findings suggest that songs are changing across generations; however, it is not known if this species also exhibits immediate flexibility. Here, we conducted an exploratory, observational study to ask whether males change the minimum frequency of their song in response to immediate changes in noise levels. We also ask whether males sing louder, as increased minimum frequency may be physiologically linked to producing sound at higher amplitudes, in response to immediate changes in environmental noise. We found that territorial males adjust song amplitude but not minimum frequency in response to changes in environmental noise levels. Our results suggest that males do not show immediate flexibility in song minimum frequency, although experimental manipulations are needed to test this hypothesis further. Our work highlights the need to investigate multiple mechanisms of adaptive response to soundscapes.
Callan, Akiko; Callan, Daniel; Ando, Hiroshi
2017-02-01
Humans can easily recognize the motion of living creatures using only a handful of point-lights that describe the motion of the main joints (biological motion perception). This special ability to perceive the motion of animate objects signifies the importance of the spatiotemporal information in perceiving biological motion. The posterior STS (pSTS) and posterior middle temporal gyrus (pMTG) region have been established by many functional neuroimaging studies as a locus for biological motion perception. Because listening to a walking human also activates the pSTS/pMTG region, the region has been proposed to be supramodal in nature. In this study, we investigated whether the spatiotemporal information from simple auditory stimuli is sufficient to activate this biological motion area. We compared spatially moving white noise, having a running-like tempo that was consistent with biological motion, with stationary white noise. The moving-minus-stationary contrast showed significant differences in activation of the pSTS/pMTG region. Our results suggest that the spatiotemporal information of the auditory stimuli is sufficient to activate the biological motion area.
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Gaididei, Yuri Borisovich; Rasmussen, Kim
1996-01-01
in an exponentially decreasing width of the solution in the long-time limit. We also find that a sufficiently large noise variance may cause an initially localized distribution to spread instead of contracting, and that the critical variance necessary to cause dispersion will for small damping be the same......We study the effect of adding noise and nonlinear damping in the two-dimensional nonlinear Schrodinger equation (NLS). Using a collective approach, we find that for initial conditions where total collapse occurs in the unperturbed NLS, the presence of the damping term will instead...
International Nuclear Information System (INIS)
Allen, Bruce; Creighton, Jolien D.E.; Flanagan, Eanna E.; Romano, Joseph D.
2003-01-01
In a previous paper (paper I), we derived a set of near-optimal signal detection techniques for gravitational wave detectors whose noise probability distributions contain non-Gaussian tails. The methods modify standard methods by truncating or clipping sample values which lie in those non-Gaussian tails. The methods were derived, in the frequentist framework, by minimizing false alarm probabilities at fixed false detection probability in the limit of weak signals. For stochastic signals, the resulting statistic consisted of a sum of an autocorrelation term and a cross-correlation term; it was necessary to discard 'by hand' the autocorrelation term in order to arrive at the correct, generalized cross-correlation statistic. In the present paper, we present an alternative derivation of the same signal detection techniques from within the Bayesian framework. We compute, for both deterministic and stochastic signals, the probability that a signal is present in the data, in the limit where the signal-to-noise ratio squared per frequency bin is small, where the signal is nevertheless strong enough to be detected (integrated signal-to-noise ratio large compared to 1), and where the total probability in the non-Gaussian tail part of the noise distribution is small. We show that, for each model considered, the resulting probability is to a good approximation a monotonic function of the detection statistic derived in paper I. Moreover, for stochastic signals, the new Bayesian derivation automatically eliminates the problematic autocorrelation term
Benson, Randall R; Gattu, Ramtilak; Cacace, Anthony T
2014-03-01
Diffusion tensor imaging (DTI) is a contemporary neuroimaging modality used to study connectivity patterns and microstructure of white matter tracts in the brain. The use of DTI in the study of tinnitus is a relatively unexplored methodology with no studies focusing specifically on tinnitus induced by noise exposure. In this investigation, participants were two groups of adults matched for etiology, age, and degree of peripheral hearing loss, but differed by the presence or absence (+/-) of tinnitus. It is assumed that matching individuals on the basis of peripheral hearing loss, allows for differentiating changes in white matter microstructure due to hearing loss from changes due to the effects of chronic tinnitus. Alterations in white matter tracts, using the fractional anisotropy (FA) metric, which measures directional diffusion of water, were quantified using tract-based spatial statistics (TBSS) with additional details provided by in vivo probabilistic tractography. Our results indicate that 10 voxel clusters differentiated the two groups, including 9 with higher FA in the group with tinnitus. A decrease in FA was found for a single cluster in the group with tinnitus. However, seven of the 9 clusters with higher FA were in left hemisphere thalamic, frontal, and parietal white matter. These foci were localized to the anterior thalamic radiations and the inferior and superior longitudinal fasciculi. The two right-sided clusters with increased FA were located in the inferior fronto-occipital fasciculus and superior longitudinal fasciculus. The only decrease in FA for the tinnitus-positive group was found in the superior longitudinal fasciculus of the left parietal lobe. Copyright © 2013 Elsevier B.V. All rights reserved.
Hogsden, Jennifer L; Dringenberg, Hans C
2009-08-01
The composition of N-methyl-D-aspartate (NMDA) receptor subunits influences the degree of synaptic plasticity expressed during development and into adulthood. Here, we show that theta-burst stimulation of the medial geniculate nucleus reliably induced NMDA receptor-dependent long-term potentiation (LTP) of field postsynaptic potentials recorded in the primary auditory cortex (A1) of urethane-anesthetized rats. Furthermore, substantially greater levels of LTP were elicited in juvenile animals (30-37 days old; approximately 55% maximal potentiation) than in adult animals (approximately 30% potentiation). Masking patterned sound via continuous white noise exposure during early postnatal life (from postnatal day 5 to postnatal day 50-60) resulted in enhanced, juvenile-like levels of LTP (approximately 70% maximal potentiation) relative to age-matched controls reared in unaltered acoustic environments (approximately 30%). Rats reared in white noise and then placed in unaltered acoustic environments for 40-50 days showed levels of LTP comparable to those of adult controls, indicating that white noise rearing results in a form of developmental arrest that can be overcome by subsequent patterned sound exposure. We explored the mechanisms mediating white noise-induced plasticity enhancements by local NR2B subunit antagonist application in A1. NR2B subunit antagonists (Ro 25-6981 or ifenprodil) completely reversed white noise-induced LTP enhancement at concentrations that did not affect LTP in adult or age-matched controls. We conclude that white noise exposure during early postnatal life results in the maintenance of juvenile-like, higher levels of plasticity in A1, an effect that appears to be critically dependent on NR2B subunit activation.
Three-dimensional hydrodynamical simulations of stellar collisions. II. White dwarfs
International Nuclear Information System (INIS)
Benz, W.; Thielemann, F.K.; Hills, J.G.
1989-01-01
Three-dimensional numerical simulations are presented for collisions between white dwarfs, using a smooth-particle hydrodynamics code with 5000 particles. The code allows for radiation and degenerate pressure and uses a reduced nuclear network which models the large release of nuclear energy. Two different collision models are considered over a range of impact parameters: between two 0.06 solar-mass C-O white dwarfs and between 0.9 solar-mass and 0.7 solar-mass C-O white dwarfs. In nearly head-on collisions, a very substantial fraction of the mass is lost as a result of a large release of nuclear energy. In grazing collisions, the fraction of mass lost is close to that produced in collisions between main-sequence stars. The quantity of processed elements ejected into the ISM by these collisions does not significantly affect the chemical evolution of the Galaxy. 24 refs
2MASS J06562998+3002455: Not a Cool White Dwarf Candidate, but a Population II Halo Star
de la Fuente Marcos, Raúl; de la Fuente Marcos, Carlos
2018-06-01
2MASS J06562998+3002455 or PSS 309-6 is a high proper-motion star that was discovered during a survey with the 2.1 m telescope at Kitt Peak National Observatory. Here, we reevaluate the status of this interesting star using Gaia DR2. Our results strongly suggest that PSS 309-6 could be a Population II star as the value of its V component is close to -220 km/s, which is typical for halo stars in the immediate solar neighborhood. Kapteyn's star is the nearest known halo star and PSS 309-6 exhibits similar kinematic and photometric signatures. Its properties also resemble those of 2MASS J15484023-3544254, which was once thought to be the nearest cool white dwarf but was later reclassified as K-type subdwarf. Although it is virtually certain that PSS 309-6 is not a nearby white dwarf but a more distant Population II subdwarf, further spectroscopic information, including radial velocity measurements, is necessary to fully characterize this probable member of the Galactic halo.
Novel matched amplifiers with low noise positive feedback. Part II: Resistive-capacitive feedback
Bruck, Y.; Zakharenko, V.
2010-02-01
This article is a continuation of consideration for an amplifier with resistive positive feedback (RPF) (Bruck (2008), 'Novel Matched LNA with Low Noise Positive Feedback. Part 1: General Features and Resistive Feedback', International Journal of Electronics, 95, 441-456). We propose here new configuration schematics of a transformer-less selective LNA with resistive-capacitive positive feedback (RCPF). A circuit of an amplifier with a transistor connected into a circuit with a common base (CB) configuration is analysed in detail. RCPF and RPF circuits are compared. It is shown that the LNA RCPF provides any pass-band, a good level of input and output matching, a minimum noise temperature which is significantly lower than that of the LNA RPF, a rather high linearity, and stability of amplification. The simulation results and some experimental data for the amplifiers intended for use in the LOFAR radiotelescope (Konovalenko et al. (2003), 'Thirty Element Array Antenna as a Prototype of a Huge Low-Frequency Radio Telescope,' Experimental Astronomy, 16, 149-164; Konovalenko (2007), 'Ukrainian Contribution to LOFAR', A scientific workshop, organised by LOFAR/ASTRON' Emmen, Netherlands, 23-27. http://www.lofar.org/workshop) are given. It is assumed that such devices are of a special interest for high-frequency integral circuits (IC).
Walsh, Kyle P.; Pasanen, Edward G.; McFadden, Dennis
2014-01-01
Human subjects performed in several behavioral conditions requiring, or not requiring, selective attention to visual stimuli. Specifically, the attentional task was to recognize strings of digits that had been presented visually. A nonlinear version of the stimulus-frequency otoacoustic emission (SFOAE), called the nSFOAE, was collected during the visual presentation of the digits. The segment of the physiological response discussed here occurred during brief silent periods immediately following the SFOAE-evoking stimuli. For all subjects tested, the physiological-noise magnitudes were substantially weaker (less noisy) during the tasks requiring the most visual attention. Effect sizes for the differences were >2.0. Our interpretation is that cortico-olivo influences adjusted the magnitude of efferent activation during the SFOAE-evoking stimulation depending upon the attention task in effect, and then that magnitude of efferent activation persisted throughout the silent period where it also modulated the physiological noise present. Because the results were highly similar to those obtained when the behavioral conditions involved auditory attention, similar mechanisms appear to operate both across modalities and within modalities. Supplementary measurements revealed that the efferent activation was spectrally global, as it was for auditory attention. PMID:24732070
Energy Technology Data Exchange (ETDEWEB)
Goswami, Gurupada; Majee, Pradip; Bag, Bidhan Chandra [Department of Chemistry, Visva-Bharati, Santiniketan 731 235 (India); Barik, Debashis [Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India)
2006-09-15
In this paper we have studied upper bound of time derivative of information entropy for colored cross-correlated noise driven open systems. The upper bound is calculated based on the Fokker-Planck equation and the Schwartz inequality principle. Our results consider the effect of the noise correlation strength and correlation time due to the correlation between additive and multiplicative white noises on the upper bound as well as relaxation time. The interplay of deterministic and random forces reveals extremal nature of the upper bound and its deviation from the time derivative of information entropy. (author)
Chesca, Boris; John, Daniel; Mellor, Christopher J.
2015-10-01
A very promising direction to improve the sensitivity of magnetometers based on superconducting quantum interference devices (SQUIDs) is to build a series-array of N non-interacting SQUIDs operating flux-coherently, because in this case their voltage modulation depth, ΔV, linearly scales with N whereas the white flux noise SΦ1/2 decreases as 1/N1/2. Here, we report the realization of both these improvements in an advanced layout of very large SQUID arrays made of YBa2Cu3O7. Specially designed with large area narrow flux focusers for increased field sensitivity and improved flux-coherency, our arrays have extremely low values for SΦ1/2 between (0.25 and 0.44) μΦ0/Hz1/2 for temperatures in the range (77-83) K. In this respect, they outperform niobium/aluminium trilayer technology-based single-SQUIDs operating at 4.2 K. Moreover, with values for ΔV and transimpedance in the range of (10-17) mV and (0.3-2.5) kΩ, respectively, a direct connection to a low-noise room temperature amplifier is allowed, while matching for such readout is simplified and the available bandwidth is greatly increased. These landmark performances suggest such series SQUID arrays are ideal candidates to replace single-SQUIDs operating at 4.2 K in many applications.
International Nuclear Information System (INIS)
Pazsit, I.; Glockler, O.
1984-01-01
In an earlier publication, using the theory of neutron fluctuations induced by a vibrating control rod, a complete formal solution of rod vibration diagnostics based on neutron noise measurements was given in terms of Fourier-transformed neutron detector time signals. The suggested procedure was checked in numerical simulation tests where only periodic vibrations could be considered. The procedure and its numerical testing are elaborated for stochastic two-dimensional vibrations. A simple stochastic theory of two-dimensional flow-induced vibrations is given; then the diagnostic method is formulated in the stochastic case, that is, in terms of neutron detector auto- and crosspower spectra. A previously suggested approximate rod localization technique is also formulated in the stochastic case. Applicability of the methods is then investigated in numerical simulation tests, using the proposed model of stochastic two-dimensional vibrations when generating neutron detector spectra that simulate measured data
Debussche, A.; Glatt-Holtz, N.; Temam, R.; Ziane, M.
2012-07-01
The primitive equations (PEs) are a basic model in the study of large scale oceanic and atmospheric dynamics. These systems form the analytical core of the most advanced general circulation models. For this reason and due to their challenging nonlinear and anisotropic structure, the PEs have recently received considerable attention from the mathematical community. On the other hand, in view of the complex multi-scale nature of the earth's climate system, many uncertainties appear that should be accounted for in the basic dynamical models of atmospheric and oceanic processes. In the climate community stochastic methods have come into extensive use in this connection. For this reason there has appeared a need to further develop the foundations of nonlinear stochastic partial differential equations in connection with the PEs and more generally. In this work we study a stochastic version of the PEs. We establish the global existence and uniqueness of strong, pathwise solutions for these equations in dimension 3 for the case of a nonlinear multiplicative noise. The proof makes use of anisotropic estimates, L^{p}_{t}L^{q}_{x} estimates on the pressure and stopping time arguments.
International Nuclear Information System (INIS)
Debussche, A; Glatt-Holtz, N; Temam, R; Ziane, M
2012-01-01
The primitive equations (PEs) are a basic model in the study of large scale oceanic and atmospheric dynamics. These systems form the analytical core of the most advanced general circulation models. For this reason and due to their challenging nonlinear and anisotropic structure, the PEs have recently received considerable attention from the mathematical community. On the other hand, in view of the complex multi-scale nature of the earth's climate system, many uncertainties appear that should be accounted for in the basic dynamical models of atmospheric and oceanic processes. In the climate community stochastic methods have come into extensive use in this connection. For this reason there has appeared a need to further develop the foundations of nonlinear stochastic partial differential equations in connection with the PEs and more generally. In this work we study a stochastic version of the PEs. We establish the global existence and uniqueness of strong, pathwise solutions for these equations in dimension 3 for the case of a nonlinear multiplicative noise. The proof makes use of anisotropic estimates, L p t L q x estimates on the pressure and stopping time arguments
Salehizadeh, S M A; Dao, Duy K; Chong, Jo Woon; McManus, David; Darling, Chad; Mendelson, Yitzhak; Chon, Ki H
2014-11-01
We introduce a new method to reconstruct motion and noise artifact (MNA) contaminated photoplethysmogram (PPG) data. A method to detect MNA corrupted data is provided in a companion paper. Our reconstruction algorithm is based on an iterative motion artifact removal (IMAR) approach, which utilizes the singular spectral analysis algorithm to remove MNA artifacts so that the most accurate estimates of uncorrupted heart rates (HRs) and arterial oxygen saturation (SpO2) values recorded by a pulse oximeter can be derived. Using both computer simulations and three different experimental data sets, we show that the proposed IMAR approach can reliably reconstruct MNA corrupted data segments, as the estimated HR and SpO2 values do not significantly deviate from the uncorrupted reference measurements. Comparison of the accuracy of reconstruction of the MNA corrupted data segments between our IMAR approach and the time-domain independent component analysis (TD-ICA) is made for all data sets as the latter method has been shown to provide good performance. For simulated data, there were no significant differences in the reconstructed HR and SpO2 values starting from 10 dB down to -15 dB for both white and colored noise contaminated PPG data using IMAR; for TD-ICA, significant differences were observed starting at 10 dB. Two experimental PPG data sets were created with contrived MNA by having subjects perform random forehead and rapid side-to-side finger movements show that; the performance of the IMAR approach on these data sets was quite accurate as non-significant differences in the reconstructed HR and SpO2 were found compared to non-contaminated reference values, in most subjects. In comparison, the accuracy of the TD-ICA was poor as there were significant differences in reconstructed HR and SpO2 values in most subjects. For non-contrived MNA corrupted PPG data, which were collected with subjects performing walking and stair climbing tasks, the IMAR significantly
K2 Ultracool Dwarfs Survey. II. The White Light Flare Rate of Young Brown Dwarfs
Gizis, John E.; Paudel, Rishi R.; Mullan, Dermott; Schmidt, Sarah J.; Burgasser, Adam J.; Williams, Peter K. G.
2017-08-01
We use Kepler K2 Campaign 4 short-cadence (one-minute) photometry to measure white light flares in the young, moving group brown dwarfs 2MASS J03350208+2342356 (2M0335+23) and 2MASS J03552337+1133437 (2M0355+11), and report on long-cadence (thirty-minute) photometry of a superflare in the Pleiades M8 brown dwarf CFHT-PL-17. The rotation period (5.24 hr) and projected rotational velocity (45 km s-1) confirm 2M0335+23 is inflated (R≥slant 0.20 {R}⊙ ) as predicted for a 0.06 {M}⊙ , 24 Myr old brown dwarf βPic moving group member. We detect 22 white light flares on 2M0335+23. The flare frequency distribution follows a power-law distribution with slope -α =-1.8+/- 0.2 over the range 1031 to 1033 erg. This slope is similar to that observed in the Sun and warmer flare stars, and is consistent with lower-energy flares in previous work on M6-M8 very-low-mass stars; taking the two data sets together, the flare frequency distribution for ultracool dwarfs is a power law over 4.3 orders of magnitude. The superflare (2.6× {10}34 erg) on CFHT-PL-17 shows higher-energy flares are possible. We detect no flares down to a limit of 2× {10}30 erg in the nearby L5γ AB Dor moving group brown dwarf 2M0355+11, consistent with the view that fast magnetic reconnection is suppressed in cool atmospheres. We discuss two multi-peaked flares observed in 2M0335+23, and argue that these complex flares can be understood as sympathetic flares, in which fast-mode magnetohydrodynamic waves similar to extreme-ultraviolet waves in the Sun trigger magnetic reconnection in different active regions.
KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243
Energy Technology Data Exchange (ETDEWEB)
Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M. [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195 (United States); Hebb, Leslie [Department of Physics, Hobart and William Smith Colleges, 300 Pulteney Street, Geneva, NY 14456 (United States); Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R. [HL Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks Street, Norman, OK 73019 (United States); Kowalski, Adam F. [NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States); Hilton, Eric J., E-mail: jrad@astro.washington.edu [Universe Sandbox, 911 E. Pike Street #333, Seattle, WA 98122 (United States)
2014-12-20
We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10{sup 29} to 10{sup 33} erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events.
KEPLER FLARES. II. THE TEMPORAL MORPHOLOGY OF WHITE-LIGHT FLARES ON GJ 1243
International Nuclear Information System (INIS)
Davenport, James R. A.; Hawley, Suzanne L.; Johnson, Emily C.; Peraza, Jesus; Jansen, Tiffany C.; Larsen, Daniel M.; Hebb, Leslie; Wisniewski, John P.; Malatesta, Michael; Keil, Marcus; Silverberg, Steven M.; Scheffler, Matthew S.; Berdis, Jodi R.; Kowalski, Adam F.; Hilton, Eric J.
2014-01-01
We present the largest sample of flares ever compiled for a single M dwarf, the active M4 star GJ 1243. Over 6100 individual flare events, with energies ranging from 10 29 to 10 33 erg, are found in 11 months of 1 minute cadence data from Kepler. This sample is unique for its completeness and dynamic range. We have developed automated tools for finding flares in short-cadence Kepler light curves, and performed extensive validation and classification of the sample by eye. From this pristine sample of flares we generate a median flare template. This template shows that two exponential cooling phases are present during the white-light flare decay, providing fundamental constraints for models of flare physics. The template is also used as a basis function to decompose complex multi-peaked flares, allowing us to study the energy distribution of these events. Only a small number of flare events are not well fit by our template. We find that complex, multi-peaked flares occur in over 80% of flares with a duration of 50 minutes or greater. The underlying distribution of flare durations for events 10 minutes and longer appears to follow a broken power law. Our results support the idea that sympathetic flaring may be responsible for some complex flare events
Monte Carlo Solutions for Blind Phase Noise Estimation
Directory of Open Access Journals (Sweden)
Çırpan Hakan
2009-01-01
Full Text Available This paper investigates the use of Monte Carlo sampling methods for phase noise estimation on additive white Gaussian noise (AWGN channels. The main contributions of the paper are (i the development of a Monte Carlo framework for phase noise estimation, with special attention to sequential importance sampling and Rao-Blackwellization, (ii the interpretation of existing Monte Carlo solutions within this generic framework, and (iii the derivation of a novel phase noise estimator. Contrary to the ad hoc phase noise estimators that have been proposed in the past, the estimators considered in this paper are derived from solid probabilistic and performance-determining arguments. Computer simulations demonstrate that, on one hand, the Monte Carlo phase noise estimators outperform the existing estimators and, on the other hand, our newly proposed solution exhibits a lower complexity than the existing Monte Carlo solutions.
Tran Thi Tuyet, H.; Zwart, M.P.; Phuong, N.T.; Oanh, D.T.H.; Jong, de M.C.M.; Vlak, J.M.
2012-01-01
Sequence comparisons of the genomes of white spot syndrome virus (WSSV) strains have identified regions containing variable-length insertions/deletions (i.e. indels). Indel-I and Indel-II, positioned between open reading frames (ORFs) 14/15 and 23/24, respectively, are the largest and the most
Che, Chi-Ming; Chan, Siu-Chung; Xiang, Hai-Feng; Chan, Michael C W; Liu, Yu; Wang, Yue
2004-07-07
The capabilities of readily prepared and sublimable Pt(II) Schiff base triplet emitters as OLED dopants have been examined; maximum luminous and power efficiencies and luminance of 31 cd A(-1), 14 lm W(-1), and 23,000 cd m(-2), respectively, and white EL (CIE: 0.33, 0.35) by simultaneous host/dopant emission, have been achieved.
Stupfel, M; Molin, D; Thierry, H; Busnel, M C
1980-01-01
A white noise is emitted during 2 h, either in the middle of the scotoperiod (activity period) or of the photoperiod (rest period), on grouped specific pathogen free (SPF) male Sprague-Dawley rats, LD 12:12 synchronized by light (L = 6 h = 150 lux). Continuous measurements of VCO2, taken as an index of respiratory activity shows: 1. a short increase both after the beginning and the end of the stimulus, with slight time length differences between young and older rats; 2. a slight (2-3%) continued increase during the photoperiod and a high decrease (13%) during the scotoperiod. These VCO2 variations obtained during and after the white noise emission correspond to measurements of activity displacement and observations of behavior performed on a small sample of rats.
Wild, Emily C.
1998-01-01
This report provides the results of a detailed Level II analysis of scour potential at structure TUNBTH00600032 on Town Highway 60 crossing the First Branch White River, Tunbridge, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 92.9-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge, while woody vegetation sparsely covers the immediate banks. In the study area, the First Branch White River has a sinuous channel with a slope of approximately 0.001 ft/ft, an average channel top width of 82 ft and an average bank height of 7 ft. The channel bed material ranges from sand to gravel with a median grain size (D50) of 24.4 mm (0.08 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 18, 1995, indicated that the reach was laterally unstable, as a result of block failure of moderately eroded banks. The Town Highway 60 crossing of the First Branch White River is a 74-ft-long, one-lane bridge consisting of a 71-foot timber thru-truss span (Vermont Agency of Transportation, written communication, August 24, 1994). The opening length of the structure parallel to the bridge face is 64 ft.The bridge is supported by vertical, laid-up stone abutments with upstream wingwalls. The channel is not skewed to the opening
Wild, Emily C.; Degnan, James
1997-01-01
This report provides the results of a detailed Level II analysis of scour potential at structure ROCHTH00210034 on Town Highway 21 crossing the White River, Rochester, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, obtained from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D.The site is in the Green Mountain section of the New England physiographic province in central Vermont. The 74.8-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is suburban on the upstream and downstream left overbanks, though brush prevails along the immediate banks. On the upstream and downstream right overbanks, the surface cover is pasture with brush and trees along the immediate banks.In the study area, the White River has an incised, straight channel with a slope of approximately 0.002 ft/ft, an average channel top width of 102 ft and an average bank height of 5 ft. The channel bed material ranges from sand to cobble with a median grain size (D50) of 74.4 mm (0.244 ft). The geomorphic assessment at the time of the Level I and Level II site visit on July 23, 1996, indicated that the reach was stable.The Town Highway 21 crossing of the White River is a 72-ft-long, two-lane bridge consisting of 70-foot steel stringer span (Vermont Agency of Transportation, written communication, March 22, 1995). The opening length of the structure parallel to the bridge face is 67.0 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 15
Vilar, J. M. G. (José M. G.), 1972-; Rubí Capaceti, José Miguel
2001-01-01
We have analyzed the interplay between an externally added noise and the intrinsic noise of systems that relax fast towards a stationary state, and found that increasing the intensity of the external noise can reduce the total noise of the system. We have established a general criterion for the appearance of this phenomenon and discussed two examples in detail.
Acoustic noise in functional magnetic resonance imaging reduces pain unpleasantness ratings.
Boyle, Y; Bentley, D E; Watson, A; Jones, A K P
2006-07-01
Functional magnetic resonance imaging (fMRI) is increasingly used in cognitive studies. Unfortunately, the scanner produces acoustic noise during the image acquisition process. Interference from acoustic noise is known to affect auditory, visual and motor processing, raising the possibility that acoustic interference may also modulate processing of other sensory modalities such as pain. With the increasing use of fMRI in the investigation of the mechanisms of pain perception, particularly in relation to attention, this issue has become highly relevant. Pain is a complex experience, composed of sensory-discriminative, affective-motivational and cognitive-evaluative components. The aim of this experiment was to assess the effect of MRI scanner noise, compared to white noise, on the affective (unpleasantness) and the sensory-discriminative (localisation) components of pain. Painful radiant heat from a CO(2) laser was delivered to the skin of the right forearm in 24 healthy volunteers. The volunteers attended to either pain location or pain unpleasantness during three conditions: i) no noise, ii) exposure to MRI scanner noise (85 dB) or iii) exposure to white noise (85 dB). Both MRI scanner noise and white noise significantly reduced unpleasantness ratings (from 5.1 +/- 1.6 in the control condition to 4.7 +/- 1.5 (P = 0.002) and 4.6 +/- 1.6 (P white noise respectively), whereas the ability to localise pain was not significantly affected (from 85.4 +/- 9.2% correct in the control condition to 83.1 +/- 10.3% (P = 0.06) and 83.9 +/- 9.5% (P = 0.27) with MRI scanner and white noise respectively). This phenomenon should be taken into account in the design of fMRI studies into human pain perception.
2010-03-01
The University of Toledo University Transportation Center (UT-UTC) has identified hybrid vehicles as one of the three areas of the research. The activities proposed in this research proposal are directed towards the noise, vibration, and harshness (N...
2010-03-01
The University of Toledo University Transportation Center (UT-UTC) has identified hybrid vehicles as one of the three areas of the research. The activities proposed in this research proposal are directed towards the noise, vibration, and harshness (N...
DEFF Research Database (Denmark)
Dierking, Wolfgang; Dall, Jørgen
2008-01-01
C- and L-band airborne synthetic aperture radar (SAR) imagery acquired at like- and cross-polarization over sea ice under winter conditions is examined with the objective to study the discrimination between level ice and ice deformation features. High-resolution low-noise data were analysed...... in the first paper. In this second paper, the main topics are the effects of spatial resolution and signal-to-noise ratio. Airborne, high-resolution SAR scenes are used to generate a sequence of images with increasingly coarser spatial resolution from 5 m to 25 m, keeping the number of looks constant....... The signal-to-noise ratio is varied between typical noise levels for airborne imagery and satellite data. Areal fraction of deformed ice and average deformation distance are determined for each image product. At L-band, the retrieved values of the areal fraction get larger as the image resolution is degraded...
Kompis, Martin; Bertram, Matthias; Senn, Pascal; Müller, Joachim; Pelizzone, Marco; Häusler, Rudolf
2008-01-01
Users of cochlear implants (auditory aids, which stimulate the auditory nerve electrically at the inner ear) often suffer from poor speech understanding in noise. We evaluate a small (intermicrophone distance 7 mm) and computationally inexpensive adaptive noise reduction system suitable for behind-the-ear cochlear implant speech processors. The system is evaluated in simulated and real, anechoic and reverberant environments. Results from simulations show improvements of 3.4 to 9.3 dB in signa...
Sams-Dodd, F; Capranica, R R
1996-10-01
Acoustic signals are generally encoded in the peripheral auditory system of vertebrates by a duality scheme. For frequency components that fall within the excitatory tuning curve, individual eighth nerve fibers can encode the effective spectral energy by a spike-rate code, while simultaneously preserving the signal waveform periodicity of lower frequency components by phase-locked spike-train discharges. To explore how robust this duality of representation may be in the presence of noise, we recorded the responses of auditory fibers in the eighth nerve of the Tokay gecko to tonal stimuli when masking noise was added simultaneously. We found that their spike-rate functions reached plateau levels fairly rapidly in the presence of noise, so the ability to signal the presence of a tone by a concomitant change in firing rate was quickly lost. On the other hand, their synchronization functions maintained a high degree of phase-locked firings to the tone even in the presence of high-intensity masking noise, thus enabling a robust detection of the tonal signal. Critical ratios (CR) and critical bandwidths showed that in the frequency range where units are able to phaselock to the tonal periodicity, the CR bands were relatively narrow and the bandwidths were independent of noise level. However, to higher frequency tones where phaselocking fails and only spike-rate codes apply, the CR bands were much wider and depended upon noise level, so that their ability to filter tones out of a noisy background degraded with increasing noise levels. The greater robustness of phase-locked temporal encoding contrasted with spike-rate coding verifies a important advantage in using lower frequency signals for communication in noisy environments.
International Nuclear Information System (INIS)
Bismarck, V.E.
1986-01-01
In the present work, our purpose was make a cephalometric-radiographic study, comparing white Brazilian teenagers who presented normal occlusion and the ones who presented malocclusions of Class I and Class II, according to RICKETT'S analysis (1960). (author) [pt
International Nuclear Information System (INIS)
Farihi, J.; Hoard, D. W.; Wachter, S.
2010-01-01
Results are presented for a Hubble Space Telescope Advanced Camera for Surveys high-resolution imaging campaign of 90 white dwarfs with known or suspected low-mass stellar and substellar companions. Of the 72 targets that remain candidate and confirmed white dwarfs with near-infrared excess, 43 are spatially resolved into two or more components, and a total of 12 systems are potentially triples. For 68 systems where a comparison is possible, 50% have significant photometric distance mismatches between their white dwarf and M dwarf components, suggesting that white dwarf parameters derived spectroscopically are often biased due to the cool companion. Interestingly, 9 of the 30 binaries known to have emission lines are found to be visual pairs and hence widely separated, indicating an intrinsically active cool star and not irradiation from the white dwarf. There is a possible, slight deficit of earlier spectral types (bluer colors) among the spatially unresolved companions, exactly the opposite of expectations if significant mass is transferred to the companion during the common envelope phase. Using the best available distance estimates, the low-mass companions to white dwarfs exhibit a bimodal distribution in projected separation. This result supports the hypothesis that during the giant phases of the white dwarf progenitor, any unevolved companions either migrate inward to short periods of hours to days, or outward to periods of hundreds to thousands of years. No intermediate projected separations of a few to several AU are found among these pairs. However, a few double M dwarfs (within triples) are spatially resolved in this range, empirically demonstrating that such separations were readily detectable among the binaries with white dwarfs. A straightforward and testable prediction emerges: all spatially unresolved, low-mass stellar and substellar companions to white dwarfs should be in short-period orbits. This result has implications for substellar companion and
Approximations to camera sensor noise
Jin, Xiaodan; Hirakawa, Keigo
2013-02-01
Noise is present in all image sensor data. Poisson distribution is said to model the stochastic nature of the photon arrival process, while it is common to approximate readout/thermal noise by additive white Gaussian noise (AWGN). Other sources of signal-dependent noise such as Fano and quantization also contribute to the overall noise profile. Question remains, however, about how best to model the combined sensor noise. Though additive Gaussian noise with signal-dependent noise variance (SD-AWGN) and Poisson corruption are two widely used models to approximate the actual sensor noise distribution, the justification given to these types of models are based on limited evidence. The goal of this paper is to provide a more comprehensive characterization of random noise. We concluded by presenting concrete evidence that Poisson model is a better approximation to real camera model than SD-AWGN. We suggest further modification to Poisson that may improve the noise model.
International Nuclear Information System (INIS)
Spagnolo, B.; Agudov, N.V.; Dubkov, A.A.
2004-01-01
The noise can stabilize a fluctuating or a periodically driven metastable state in such a way that the system remains in this state for a longer time than in the absence of white noise. This is the noise enhanced stability phenomenon, observed experimentally and numerically in different physical systems. After shortly reviewing all the physical systems where the phenomenon was observed, the theoretical approaches used to explain the effect are presented. Specifically the conditions to observe the effect in systems: (a) with periodical driving force, and (b) with random dichotomous driving force, are discussed. In case (b) we review the analytical results concerning the mean first passage time and the nonlinear relaxation time as a function of the white noise intensity, the parameters of the potential barrier, and of the dichotomous noise. (author)
Halim, Dunant; Cheng, Li; Su, Zhongqing
2011-04-01
The work proposed an optimization approach for structural sensor placement to improve the performance of vibro-acoustic virtual sensor for active noise control applications. The vibro-acoustic virtual sensor was designed to estimate the interior sound pressure of an acoustic-structural coupled enclosure using structural sensors. A spectral-spatial performance metric was proposed, which was used to quantify the averaged structural sensor output energy of a vibro-acoustic system excited by a spatially varying point source. It was shown that (i) the overall virtual sensing error energy was contributed additively by the modal virtual sensing error and the measurement noise energy; (ii) each of the modal virtual sensing error system was contributed by both the modal observability levels for the structural sensing and the target acoustic virtual sensing; and further (iii) the strength of each modal observability level was influenced by the modal coupling and resonance frequencies of the associated uncoupled structural/cavity modes. An optimal design of structural sensor placement was proposed to achieve sufficiently high modal observability levels for certain important panel- and cavity-controlled modes. Numerical analysis on a panel-cavity system demonstrated the importance of structural sensor placement on virtual sensing and active noise control performance, particularly for cavity-controlled modes.
Rebassa-Mansergas, A.; Ren, J. J.; Irawati, P.; García-Berro, E.; Parsons, S. G.; Schreiber, M. R.; Gänsicke, B. T.; Rodríguez-Gil, P.; Liu, X.; Manser, C.; Nevado, S. P.; Jiménez-Ibarra, F.; Costero, R.; Echevarría, J.; Michel, R.; Zorotovic, M.; Hollands, M.; Han, Z.; Luo, A.; Villaver, E.; Kong, X.
2017-12-01
We present the second paper of a series of publications aiming at obtaining a better understanding regarding the nature of type Ia supernovae (SN Ia) progenitors by studying a large sample of detached F, G and K main-sequence stars in close orbits with white dwarf companions (i.e. WD+FGK binaries). We employ the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) data release 4 spectroscopic data base together with Galaxy Evolution Explorer (GALEX) ultraviolet fluxes to identify 1549 WD+FGK binary candidates (1057 of which are new), thus doubling the number of known sources. We measure the radial velocities of 1453 of these binaries from the available LAMOST spectra and/or from spectra obtained by us at a wide variety of different telescopes around the globe. The analysis of the radial velocity data allows us to identify 24 systems displaying more than 3σ radial velocity variation that we classify as close binaries. We also discuss the fraction of close binaries among WD+FGK systems, which we find to be ∼10 per cent, and demonstrate that high-resolution spectroscopy is required to efficiently identify double-degenerate SN Ia progenitor candidates.
Energy Technology Data Exchange (ETDEWEB)
Nagayama, Yasunori [Kumamoto City Hospital, Department of Radiology, Kumamoto (Japan); Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Nakaura, Takeshi; Yuki, Hideaki; Hirarta, Kenichiro; Kidoh, Masafumi; Oda, Seitaro; Utsunomiya, Daisuke; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Tsuji, Akinori; Urata, Joji; Furusawa, Mitsuhiro [Kumamoto City Hospital, Department of Radiology, Kumamoto (Japan)
2017-07-15
To retrospectively evaluate the image quality and radiation dose of 100-kVp scans with sinogram-affirmed iterative reconstruction (IR) for unenhanced head CT in adolescents. Sixty-nine patients aged 12-17 years underwent head CT under 120- (n = 34) or 100-kVp (n = 35) protocols. The 120-kVp images were reconstructed with filtered back-projection (FBP), 100-kVp images with FBP (100-kVp-F) and sinogram-affirmed IR (100-kVp-S). We compared the effective dose (ED), grey-white matter (GM-WM) contrast, image noise, and contrast-to-noise ratio (CNR) between protocols in supratentorial (ST) and posterior fossa (PS). We also assessed GM-WM contrast, image noise, sharpness, artifacts, and overall image quality on a four-point scale. ED was 46% lower with 100- than 120-kVp (p < 0.001). GM-WM contrast was higher, and image noise was lower, on 100-kVp-S than 120-kVp at ST (p < 0.001). CNR of 100-kVp-S was higher than of 120-kVp (p < 0.001). GM-WM contrast of 100-kVp-S was subjectively rated as better than of 120-kVp (p < 0.001). There were no significant differences in the other criteria between 100-kVp-S and 120-kVp (p = 0.072-0.966). The 100-kVp with sinogram-affirmed IR facilitated dramatic radiation reduction and better GM-WM contrast without increasing image noise in adolescent head CT. (orig.)
International Nuclear Information System (INIS)
Wang Canjun; Chen Shibo; Mei Dongcheng
2006-01-01
We study the noise-induce transport and current reversal of Brownian particles in a continuously periodic potential driven by cross correlation between a multiplicative white noise and an additive white noise. We find that directed motion of the Brownian particles can be induced by the correlation between the additive noise and the multiplicative noise. The current reversal and the direction of the current is controlled by the values of the intensity (λ) of the correlated noises and a dimensionless parameter R (R=α/D, D is the intensity of multiplicative noise and α is the intensity of additive noise)
International Nuclear Information System (INIS)
Powell, Jade; Heng, Ik Siong; Torres-Forné, Alejandro; Font, José A; Lynch, Ryan; Trifirò, Daniele; Cuoco, Elena; Cavaglià, Marco
2017-01-01
The data taken by the advanced LIGO and Virgo gravitational-wave detectors contains short duration noise transients that limit the significance of astrophysical detections and reduce the duty cycle of the instruments. As the advanced detectors are reaching sensitivity levels that allow for multiple detections of astrophysical gravitational-wave sources it is crucial to achieve a fast and accurate characterization of non-astrophysical transient noise shortly after it occurs in the detectors. Previously we presented three methods for the classification of transient noise sources. They are Principal Component Analysis for Transients (PCAT), Principal Component LALInference Burst (PC-LIB) and Wavelet Detection Filter with Machine Learning (WDF-ML). In this study we carry out the first performance tests of these algorithms on gravitational-wave data from the Advanced LIGO detectors. We use the data taken between the 3rd of June 2015 and the 14th of June 2015 during the 7th engineering run (ER7), and outline the improvements made to increase the performance and lower the latency of the algorithms on real data. This work provides an important test for understanding the performance of these methods on real, non stationary data in preparation for the second advanced gravitational-wave detector observation run, planned for later this year. We show that all methods can classify transients in non stationary data with a high level of accuracy and show the benefits of using multiple classifiers. (paper)
Papoutsoglou, Sofronios E; Karakatsouli, Nafsika; Psarrou, Anna; Apostolidou, Sofia; Papoutsoglou, Eustratios S; Batzina, Alkisti; Leondaritis, Georgios; Sakellaridis, N
2015-02-01
This study presents the results of the response of Sparus aurata to three different musical stimuli, derived from the transmission (4 h per day, 5 days per week) of particular music pieces by Mozart, Romanza and Bach (140 dB(rms) re 1 μPa), compared to the same transmission level of white noise, while the underwater ambient noise in all the experimental tanks was 121 dB(rms) re 1 μPa. Using recirculating sea water facilities, 10 groups, 2 for each treatment, of 20 specimens of 11.2 ± 0.02 g (S.E.), were reared for 94 days, under 150 ± 10 l× 12L-12D, and were fed an artificial diet three times per day. Fish body weight showed significant differences after 55 days, while its maximum level was observed after the 69th day until the end of the experiment, the highest value demonstrated in Mozart (M) groups, followed by those of Romanza (R), Bach (B), control (C) and white noise (WN). SGR (M = B), %WG (M = B) and FCR (all groups fed same % b.w.) were also improved for M group. Brain neurotransmitters results exhibited significant differences in DA-dopamine, (M > B), 5HIAA (C > B), 5HIAA:5HT (WN > R), DOPAC (M > B), DOPAC:DA and (DOPAC + HVA):DA, (C > M), while no significant differences were observed in 5HT, NA, HVA and HVA:DA. No differences were observed in biometric measurements, protease activity, % fatty acids of fillet, visceral fat and liver, while differences were observed regarding carbohydrase activity and the amount (mg/g w.w.) of some fatty acids in liver, fillet and visceral fat. In conclusion, present results confirm those reported for S. aurata, concerning the observed relaxing influence--due to its brain neurotransmitters action--of the transmission of Mozart music (compared to R and B), which resulted in the achievement of maximum growth rate, body weight and improved FCR. This conclusion definitely supports the musical "understanding" and sensitivity of S. aurata to music stimuli as well as suggesting a specific effect of white noise.
Joanne Rebbeck; Amy Scherzer; Kurt. Gottschalk
2012-01-01
Understanding differences in physiological and growth strategies in low-light environments among upland oak species may help managers address the challenges of oaks' poor regeneration. Gas exchange and chlorophyll content were measured for northern red oak (Quercus rubra L.), chestnut oak (Quercus prinus L.), and white oak (...
Directory of Open Access Journals (Sweden)
Holloway Andrew C
2011-11-01
Full Text Available Abstract Background Enhancement of antimicrobial plant products e.g. pomegranate extract by copper (II sulphate is known. Such combinations have applications in various settings, including the identification of novel compositions to study, treat and control infection. Methods A combination of white tea (WT (made allowing 10 minutes infusion time at 100°C was combined with 4.8 mM copper (II sulphate and tested for antimicrobial effect on the viability of Staphylococcus aureus NCTC 06571. Comparisons were made with green (GT and black (BT teas. A WT sub-fraction (WTF Results A 30 minute incubation at room temperature of copper (II sulphate alone and combined with WT reduced the viability of S. aureus NCTC 06571 by c.a 1 log10 cfu mL-1. GT and BT with copper (II sulphate negated activity to buffer values. Combined with copper (II sulphate, vitamin C, WTF and, vitamin C plus WTF all reduced the viability of S. aureus NCTC 06571 by c.a. 3.5 log10 cfu mL-1. Independent experiments showed the results were not due to pH effects. Adding WT or WTF to copper (II sulphate resulted in increased acidity. Copper (II sulphate alone and combined with WT required c.a 300 μg mL-1 (final concentration catalase to restore S. aureus viability, WTF with copper (II sulphate and added vitamin C required c.a 600 μg mL-1. WT and WTF UV-visible spectra were similar. Conclusions WT showed no efficacy in the combinations tested. WTF was enhanced with copper (II sulphate and further with vitamin C. WT and WTF increased acidity of copper (II sulphate possibly via the formation of chemical complexes. The difference in WT/WTF absorbance possibly represented substances less concentrated or absent in WTF. Investigations to establish which WTF component/s and in what proportions additives are most effective against target organisms are warranted.
Cheng, Gang; So, Gary Kwok-Ming; To, Wai-Pong; Chen, Yong; Kwok, Chi-Chung; Ma, Chensheng; Guan, Xiangguo; Chang, Xiaoyong; Kwok, Wai-Ming; Che, Chi-Ming
2015-08-01
The synthesis and spectroscopic properties of luminescent tetranuclear zinc(ii) complexes of substituted 7-azaindoles and a series of luminescent copper(i) complexes containing 7,8-bis(diphenylphosphino)-7,8-dicarba- nido -undecaborate ligand are described. These complexes are stable towards air and moisture. Thin film samples of the luminescent copper(i) complexes in 2,6-dicarbazolo-1,5-pyridine and zinc(ii) complexes in poly(methyl methacrylate) showed emission quantum yields of up to 0.60 (for Cu-3 ) and 0.96 (for Zn-1 ), respectively. Their photophysical properties were examined by ultrafast time-resolved emission spectroscopy, temperature dependent emission lifetime measurements and density functional theory calculations. Monochromic blue and orange solution-processed OLEDs with these Zn(ii) and Cu(i) complexes as light-emitting dopants have been fabricated, respectively. Maximum external quantum efficiency (EQE) of 5.55% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.16, 0.19) were accomplished with the optimized Zn-1 -OLED while these values were, respectively 15.64% and (0.48, 0.51) for the optimized Cu-3 -OLED. Solution-processed white OLEDs having maximum EQE of 6.88%, CIE coordinates of (0.42, 0.44), and colour rendering index of 81 were fabricated by using these luminescent Zn(ii) and Cu(i) complexes as blue and orange light-emitting dopant materials, respectively.
Correlated Levy Noise in Linear Dynamical Systems
International Nuclear Information System (INIS)
Srokowski, T.
2011-01-01
Linear dynamical systems, driven by a non-white noise which has the Levy distribution, are analysed. Noise is modelled by a specific stochastic process which is defined by the Langevin equation with a linear force and the Levy distributed symmetric white noise. Correlation properties of the process are discussed. The Fokker-Planck equation driven by that noise is solved. Distributions have the Levy shape and their width, for a given time, is smaller than for processes in the white noise limit. Applicability of the adiabatic approximation in the case of the linear force is discussed. (author)
Noise characteristics of U. S. synchrotron radiation sources
International Nuclear Information System (INIS)
Powers, L.
1986-01-01
Noise characteristics of the U. S. x-ray synchrotron sources are compared in the 0--2.5-kHz region. In general, little difference is found in the characteristic frequencies of the noise on focused and unfocused beamlines of a particular source, but the magnitude and white-noise levels differ. The National Synchrotron Light Source shows the least characteristic noise and the noise that is observed is small in magnitude (2--3 times the white-noise level)
Confusion noise from LISA capture sources
International Nuclear Information System (INIS)
Barack, Leor; Cutler, Curt
2004-01-01
were at nearly their maximum possible levels (given LISA's baseline design and the level of confusion noise from galactic white dwarf binaries). This paper also contains, as intermediate steps, several results that should be useful in further studies of LISA capture sources, including (i) a calculation of the total GW energy output from generic inspirals of COs into Kerr MBHs (ii) an approximate GW energy spectrum for a typical capture, and (iii) an estimate showing that in the population of detected capture sources, roughly half the white dwarfs and a third of the neutron stars will be detected when they still have > or approx. 10 years to go before final plunge
Energy Technology Data Exchange (ETDEWEB)
Germino, Jose Carlos; Faleiros, Marcelo Meira; Moraes, Emmanuel Santos; Atvars, Teresa Dib Zambon, E-mail: kakagermino@hotmail.com [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Domingues, Raquel Aparecida [Universidade Federal de Sao Paulo (UNIFESP), SP (Brazil); Quites, Fernando Junior [Universidade Federal de Mato Grosso (UFMT), Cuiaba, MT (Brazil); Freitas, Jilian Nei de [Centro de Tecnologia da Informacao Renato Archer, Campinas, SP (Brazil)
2016-07-01
Full text: In this work we proposed a PFO composite with two salicylidene based Pt(II) coordination compounds, the [Pt(salophen)] and [Pt(sal-3,4-ben)] (red emitters), as emissive layer (EML) for Organic Light-emitting Diodes (OLEDs), combining a blue-fluorescent polymer (PFO) with red-phosphorescent Pt(II) coordination complexes in order to obtain an efficient white electroluminescent EML for WOLEDs application. Firstly, [Pt(salophen)] and [Pt(sal-3,4-ben)] were synthesized, purified and characterized by single crystal X-ray diffraction, yielding their respective expected molecular structures. The photoluminescence properties of the devices were evaluated by steady-state (electronic absorption and emission spectroscopies) and transient (fluorescence decays and TRES) measurements. It was observed the presence of non-radiative energy transfer processes between the PFO derivative and Pt(II) complexes. Posteriorly, the Pt(II) complexes were blended with PVK at 1% mol:mol ratio and OLEDs were made, leading to red-emitting devices with high color purity for the two coordination compounds. However, the two devices present low current efficiency values. In order to improve the electroluminescence properties of Pt(II) complexes PhOLEDs, PVK host was substituted by PFO at 0.5, 1.0 and 2.5% mol:mol ratios of complex and it was observed a great improvement of their optical-electronic properties in terms of luminance, voltage, current density and current efficiency in comparison to PVK composites or pure PFO devices. At 2.5% concentration, predominant bands of Pt(II) complexes were observed at low and high voltages. For the other concentrations, a different behavior was observed: the emission bands and device color were function of applied electrical field, exhibiting a red color at lower voltages (5 to 9V) and the PFO characteristic emission between 9 and 13V, leading to a white light emission at 13V. The best results were obtained for [Pt(sal-3,4-ben)] coordination compound
Busschaert, C.; Falize, É.; Michaut, C.; Bonnet-Bidaud, J.-M.; Mouchet, M.
2015-07-01
Context. Magnetic cataclysmic variables are close binary systems containing a strongly magnetized white dwarf that accretes matter coming from an M-dwarf companion. The high magnetic field strength leads to the formation of an accretion column instead of an accretion disk. High-energy radiation coming from those objects is emitted from the column close to the white dwarf photosphere at the impact region. Its properties depend on the characteristics of the white dwarf and an accurate accretion column model allows the properties of the binary system to be inferred, such as the white dwarf mass, its magnetic field, and the accretion rate. Aims: We study the temporal and spectral behaviour of the accretion region and use the tools we developed to accurately connect the simulation results to the X-ray and optical astronomical observations. Methods: The radiation hydrodynamics code Hades was adapted to simulate this specific accretion phenomena. Classical approaches were used to model the radiative losses of the two main radiative processes: bremsstrahlung and cyclotron. Synthetic light curves and X-ray spectra were extracted from numerical simulations. A fast Fourier analysis was performed on the simulated light curves. The oscillation frequencies and amplitudes in the X-ray and optical domains are studied to compare those numerical results to observational ones. Different dimensional formulae were developed to complete the numerical evaluations. Results: The complete characterization of the emitting region is described for the two main radiative regimes: when only the bremsstrahlung losses and when both cyclotron and bremsstrahlung losses are considered. The effect of the non-linear cooling instability regime on the accretion column behaviour is analysed. Variation in luminosity on short timescales (~1 s quasi-periodic oscillations) is an expected consequence of this specific dynamic. The importance of secondary shock instability on the quasi-periodic oscillation
Nagayama, Yasunori; Nakaura, Takeshi; Tsuji, Akinori; Urata, Joji; Furusawa, Mitsuhiro; Yuki, Hideaki; Hirarta, Kenichiro; Kidoh, Masafumi; Oda, Seitaro; Utsunomiya, Daisuke; Yamashita, Yasuyuki
2017-07-01
To retrospectively evaluate the image quality and radiation dose of 100-kVp scans with sinogram-affirmed iterative reconstruction (IR) for unenhanced head CT in adolescents. Sixty-nine patients aged 12-17 years underwent head CT under 120- (n = 34) or 100-kVp (n = 35) protocols. The 120-kVp images were reconstructed with filtered back-projection (FBP), 100-kVp images with FBP (100-kVp-F) and sinogram-affirmed IR (100-kVp-S). We compared the effective dose (ED), grey-white matter (GM-WM) contrast, image noise, and contrast-to-noise ratio (CNR) between protocols in supratentorial (ST) and posterior fossa (PS). We also assessed GM-WM contrast, image noise, sharpness, artifacts, and overall image quality on a four-point scale. ED was 46% lower with 100- than 120-kVp (p < 0.001). GM-WM contrast was higher, and image noise was lower, on 100-kVp-S than 120-kVp at ST (p < 0.001). CNR of 100-kVp-S was higher than of 120-kVp (p < 0.001). GM-WM contrast of 100-kVp-S was subjectively rated as better than of 120-kVp (p < 0.001). There were no significant differences in the other criteria between 100-kVp-S and 120-kVp (p = 0.072-0.966). The 100-kVp with sinogram-affirmed IR facilitated dramatic radiation reduction and better GM-WM contrast without increasing image noise in adolescent head CT. • 100-kVp head CT provides 46% radiation dose reduction compared with 120-kVp. • 100-kVp scanning improves subjective and objective GM-WM contrast. • Sinogram-affirmed IR decreases head CT image noise, especially in supratentorial region. • 100-kVp protocol with sinogram-affirmed IR is suited for adolescent head CT.
DEFF Research Database (Denmark)
Lous, Jørgen; Glenn Lauritsen, Maj Britt
2018-01-01
Objective: To search for predictive factors for language development measured by two receptive language tests for children, the Galker test (a word-recognition-in-noise test) testing hearing and vocabulary, and the Danish version of Reynell Developmental Language Scale (2nd revision, RDLS II) test...... in terms of the degree to which variables were able to predict test scores at the age of three to five years. Methods: All children aged three and five years attending 20 day-care centres for children without cognitive development issues from the Municipality of Hillerød, Denmark, were invited......, a language comprehension test. The study analysed if information about background variables and parents and pre-school teachers was predictive for test scores; if earlier middle ear disease, actual hearing loss and tympanometry was important for language development; and if the two receptive tests differed...
The interplay of intrinsic and extrinsic bounded noises in biomolecular networks.
Directory of Open Access Journals (Sweden)
Giulio Caravagna
Full Text Available After being considered as a nuisance to be filtered out, it became recently clear that biochemical noise plays a complex role, often fully functional, for a biomolecular network. The influence of intrinsic and extrinsic noises on biomolecular networks has intensively been investigated in last ten years, though contributions on the co-presence of both are sparse. Extrinsic noise is usually modeled as an unbounded white or colored gaussian stochastic process, even though realistic stochastic perturbations are clearly bounded. In this paper we consider Gillespie-like stochastic models of nonlinear networks, i.e. the intrinsic noise, where the model jump rates are affected by colored bounded extrinsic noises synthesized by a suitable biochemical state-dependent Langevin system. These systems are described by a master equation, and a simulation algorithm to analyze them is derived. This new modeling paradigm should enlarge the class of systems amenable at modeling. We investigated the influence of both amplitude and autocorrelation time of a extrinsic Sine-Wiener noise on: (i the Michaelis-Menten approximation of noisy enzymatic reactions, which we show to be applicable also in co-presence of both intrinsic and extrinsic noise, (ii a model of enzymatic futile cycle and (iii a genetic toggle switch. In (ii and (iii we show that the presence of a bounded extrinsic noise induces qualitative modifications in the probability densities of the involved chemicals, where new modes emerge, thus suggesting the possible functional role of bounded noises.
The interplay of intrinsic and extrinsic bounded noises in biomolecular networks.
Caravagna, Giulio; Mauri, Giancarlo; d'Onofrio, Alberto
2013-01-01
After being considered as a nuisance to be filtered out, it became recently clear that biochemical noise plays a complex role, often fully functional, for a biomolecular network. The influence of intrinsic and extrinsic noises on biomolecular networks has intensively been investigated in last ten years, though contributions on the co-presence of both are sparse. Extrinsic noise is usually modeled as an unbounded white or colored gaussian stochastic process, even though realistic stochastic perturbations are clearly bounded. In this paper we consider Gillespie-like stochastic models of nonlinear networks, i.e. the intrinsic noise, where the model jump rates are affected by colored bounded extrinsic noises synthesized by a suitable biochemical state-dependent Langevin system. These systems are described by a master equation, and a simulation algorithm to analyze them is derived. This new modeling paradigm should enlarge the class of systems amenable at modeling. We investigated the influence of both amplitude and autocorrelation time of a extrinsic Sine-Wiener noise on: (i) the Michaelis-Menten approximation of noisy enzymatic reactions, which we show to be applicable also in co-presence of both intrinsic and extrinsic noise, (ii) a model of enzymatic futile cycle and (iii) a genetic toggle switch. In (ii) and (iii) we show that the presence of a bounded extrinsic noise induces qualitative modifications in the probability densities of the involved chemicals, where new modes emerge, thus suggesting the possible functional role of bounded noises.
Bogachev, Mikhail I.; Bunde, Armin
2011-06-01
We study the predictability of extreme events in records with linear and nonlinear long-range memory in the presence of additive white noise using two different approaches: (i) the precursory pattern recognition technique (PRT) that exploits solely the information about short-term precursors, and (ii) the return interval approach (RIA) that exploits long-range memory incorporated in the elapsed time after the last extreme event. We find that the PRT always performs better when only linear memory is present. In the presence of nonlinear memory, both methods demonstrate comparable efficiency in the absence of white noise. When additional white noise is present in the record (which is the case in most observational records), the efficiency of the PRT decreases monotonously with increasing noise level. In contrast, the RIA shows an abrupt transition between a phase of low level noise where the prediction is as good as in the absence of noise, and a phase of high level noise where the prediction becomes poor. In the phase of low and intermediate noise the RIA predicts considerably better than the PRT, which explains our recent findings in physiological and financial records.
Noise properties of Hilbert transform evaluation
International Nuclear Information System (INIS)
Pavliček, Pavel; Svak, Vojtěch
2015-01-01
The Hilbert transform is a standard method for the calculation of the envelope and phase of a modulated signal in optical measurement methods. Usually, the intensity of light is converted into an electric signal at a detector. Therefore the actual spatially or temporally sampled signal is always affected by noise. Because the noise values of individual samples are independent, the noise can be considered as white. If the envelope and phase are calculated from the noised signal, they will also be affected by the noise. We calculate the variance and spectral density of both the envelope noise and the phase noise. We determine which parameters influence the variance and spectral density of both the envelope noise and the phase noise. Finally, we determine the influence of the noise on the measurement uncertainty in white-light interferometry and fringe-pattern analysis. (paper)
Schwent, V. L.; Hillyard, S. A.; Galambos, R.
1976-01-01
The effects of varying the rate of delivery of dichotic tone pip stimuli on selective attention measured by evoked-potential amplitudes and signal detectability scores were studied. The subjects attended to one channel (ear) of tones, ignored the other, and pressed a button whenever occasional targets - tones of a slightly higher pitch were detected in the attended ear. Under separate conditions, randomized interstimulus intervals were short, medium, and long. Another study compared the effects of attention on the N1 component of the auditory evoked potential for tone pips presented alone and when white noise was added to make the tones barely above detectability threshold in a three-channel listening task. Major conclusions are that (1) N1 is enlarged to stimuli in an attended channel only in the short interstimulus interval condition (averaging 350 msec), (2) N1 and P3 are related to different modes of selective attention, and (3) attention selectivity in multichannel listening task is greater when tones are faint and/or difficult to detect.
International Nuclear Information System (INIS)
Chesca, Boris; John, Daniel; Mellor, Christopher J.
2015-01-01
A very promising direction to improve the sensitivity of magnetometers based on superconducting quantum interference devices (SQUIDs) is to build a series-array of N non-interacting SQUIDs operating flux-coherently, because in this case their voltage modulation depth, ΔV, linearly scales with N whereas the white flux noise S Φ 1/2 decreases as 1/N 1/2 . Here, we report the realization of both these improvements in an advanced layout of very large SQUID arrays made of YBa 2 Cu 3 O 7 . Specially designed with large area narrow flux focusers for increased field sensitivity and improved flux-coherency, our arrays have extremely low values for S Φ 1/2 between (0.25 and 0.44) μΦ 0 /Hz 1/2 for temperatures in the range (77–83) K. In this respect, they outperform niobium/aluminium trilayer technology-based single-SQUIDs operating at 4.2 K. Moreover, with values for ΔV and transimpedance in the range of (10–17) mV and (0.3–2.5) kΩ, respectively, a direct connection to a low-noise room temperature amplifier is allowed, while matching for such readout is simplified and the available bandwidth is greatly increased. These landmark performances suggest such series SQUID arrays are ideal candidates to replace single-SQUIDs operating at 4.2 K in many applications
Noise estimation for remote sensing image data analysis
Du, Qian
2004-01-01
Noise estimation does not receive much attention in remote sensing society. It may be because normally noise is not large enough to impair image analysis result. Noise estimation is also very challenging due to the randomness nature of the noise (for random noise) and the difficulty of separating the noise component from the signal in each specific location. We review and propose seven different types of methods to estimate noise variance and noise covariance matrix in a remotely sensed image. In the experiment, it is demonstrated that a good noise estimate can improve the performance of an algorithm via noise whitening if this algorithm assumes white noise.
Meno, Whitney; Coss, Richard G; Perry, Susan
2013-03-01
Young animals are known to direct alarm calls at a wider range of animals than adults. If social cues are safer and/or more reliable to use than asocial cues for learning about predators, then it is expected that the development of this behavior will be affected by the social environment. Our study examined the influence of the social environment on antipredator behavior in infant, juvenile, and adult wild white-faced capuchin monkeys (Cebus capucinus) at Lomas Barbudal Biological Reserve in Costa Rica during presentations of different species of model snakes and novel models. We examined (a) the alarm calling behavior of the focal animal when alone versus in the vicinity of conspecific alarm callers and (b) the latency of conspecifics to alarm call once the focal animal alarm called. Focal animals alarm called more when alone than after hearing a conspecific alarm call. No reliable differences were found in the latencies of conspecifics to alarm call based on age or model type. Conspecifics were more likely to alarm call when focal individuals alarm called at snake models than when they alarm called at novel models. Results indicate (a) that alarm calling may serve to attract others to the predator's location and (b) that learning about specific predators may begin with a generalized response to a wide variety of species, including some nonthreatening ones, that is winnowed down via Pavlovian conditioned inhibition into a response directed toward specific dangerous species. This study reveals that conspecifics play a role in the development of antipredator behavior in white-faced capuchins. © 2012 Wiley Periodicals, Inc.
Energy Technology Data Exchange (ETDEWEB)
Malamud, Uri; Perets, Hagai B., E-mail: uri.mal@tx.technion.ac.il, E-mail: hperets@physics.technion.ac.il [Department of Physics, Technion (Israel)
2017-06-10
Most studies suggest that the pollution of white dwarf (WD) atmospheres arises from the accretion of minor planets, but the exact properties of polluting material, and in particular the evidence for water in some cases, are not yet understood. Here we study the water retention of small icy bodies in exo-solar planetary systems, as their respective host stars evolve through and off the main sequence and eventually become WDs. We explore, for the first time, a wide range of star masses and metallicities. We find that the mass of the WD progenitor star is of crucial importance for the retention of water, while its metallicity is relatively unimportant. We predict that minor planets around lower-mass WD progenitors would generally retain more water and would do so at closer distances from the WD than compared with high-mass progenitors. The dependence of water retention on progenitor mass and other parameters has direct implications for the origin of observed WD pollution, and we discuss how our results and predictions might be tested in the future as more observations of WDs with long cooling ages become available.
Directory of Open Access Journals (Sweden)
Mao Jinghe
2011-12-01
Full Text Available Abstract Background Along with obesity, physical inactivity, and family history of metabolic disorders, African American ethnicity is a risk factor for type 2 diabetes (T2D in the United States. However, little is known about the differences in gene expression and transcriptomic profiles of blood in T2D between African Americans (AA and Caucasians (CAU, and microarray analysis of peripheral white blood cells (WBCs from these two ethnic groups will facilitate our understanding of the underlying molecular mechanism in T2D and identify genetic biomarkers responsible for the disparities. Results A whole human genome oligomicroarray of peripheral WBCs was performed on 144 samples obtained from 84 patients with T2D (44 AA and 40 CAU and 60 healthy controls (28 AA and 32 CAU. The results showed that 30 genes had significant difference in expression between patients and controls (a fold change of 1.4 with a P value Conclusions These newly identified genetic markers in WBCs provide valuable information about the pathophysiology of T2D and can be used for diagnosis and pharmaceutical drug design. Our results also found that AA and CAU patients with T2D express genes and pathways differently.
Extinction risk under coloured environmental noise
Heino, M; Ripa, Jörgen; Kaitala, V
2000-01-01
Positively autocorrelated red environmental noise is characterized by a strong dependence of expected sample variance on sample length. This dependence has to be taken into account when assessing extinction risk under red and white uncorrelated environmental noise. To facilitate a comparison between red and white noise, their expected variances can be scaled to be equal, but only at a chosen time scale. We show with a simple one-dimensional population dynamics model that the different but equ...
Small fluctuations in epitaxial growth via conservative noise
International Nuclear Information System (INIS)
Patrone, Paul N; Wang Rongrong; Margetis, Dionisios
2011-01-01
We study the combined effect of growth (material deposition from above) and nearest-neighbor entropic and force-dipole interactions in a stochastically perturbed system of N line defects (steps) on a vicinal crystal surface in 1+1 dimensions. First, we formulate a general model of conservative white noise and derive simplified formulas for the terrace width distribution and terrace width correlations in the limit N → ∞ for small step fluctuations. Our general result expresses terrace width correlations as an interplay of noise covariance and step interaction strength. Second, we apply our formalism to two specific noise models which stem, respectively, from (i) the fluctuation-dissipation theorem for diffusion of adsorbed atoms; and (ii) the phenomenological consideration of deposition-flux-induced asymmetric attachment and detachment of atoms at step edges. In both cases of noise, we find that terrace width correlations decay exponentially with the step number difference; this behavior leads to vanishing correlations in the macroscopic limit. Our analysis may be used to (i) determine the noise in quasi-one-dimensional surfaces and (ii) assess the validity of previous mean field approximations.
Ueda, Yoshitomo; Misumi, Sachiyo; Suzuki, Mina; Ogawa, Shino; Nishigaki, Ruriko; Ishida, Akimasa; Jung, Cha-Gyun; Hida, Hideki
2018-01-01
We previously established neonatal white matter injury (WMI) model rat that is made by right common carotid artery dissection at postnatal day 3, followed by 6% hypoxia for 60 min. This model has fewer oligodendrocyte progenitor cells and reduced myelin basic protein (MBP) positive areas in the sensorimotor cortex, but shows no apparent neuronal loss. However, how motor deficits are induced in this model is unclear. To elucidate the relationship between myelination disturbance and concomitant motor deficits, we first performed motor function tests (gait analysis, grip test, horizontal ladder test) and then analyzed myelination patterns in the sensorimotor cortex using transmission electron microscopy (TEM) and Contactin associated protein 1 (Caspr) staining in the neonatal WMI rats in adulthood. Behavioral tests revealed imbalanced motor coordination in this model. Motor deficit scores were higher in the neonatal WMI model, while hindlimb ladder stepping scores and forelimb grasping force were comparable to controls. Prolonged forelimb swing times and decreased hindlimb paw angles on the injured side were revealed by gait analysis. TEM revealed no change in myelinated axon number and the area g-ratio in the layer II/III of the cortex. Electromyographical durations and latencies in the gluteus maximus in response to electrical stimulation of the brain area were unchanged in the model. Caspr staining revealed fewer positive dots in layers II/III of the WMI cortex, indicating fewer and/or longer myelin sheath. These data suggest that disorganization of oligodendrocyte development in layers II/III of the sensorimotor cortex relates to imbalanced motor coordination in the neonatal WMI model rat.
Effects of Colored Noise on Stochastic Resonance in Sensory Neurons
International Nuclear Information System (INIS)
Nozaki, D.; Mar, D.J.; Collins, J.J.; Grigg, P.
1999-01-01
Noise can assist neurons in the detection of weak signals via a mechanism known as stochastic resonance (SR). We demonstrate experimentally that SR-type effects can be obtained in rat sensory neurons with white noise, 1/f noise, or 1/f 2 noise. For low-frequency input noise, we show that the optimal noise intensity is the lowest and the output signal-to-noise ratio the highest for conventional white noise. We also show that under certain circumstances, 1/f noise can be better than white noise for enhancing the response of a neuron to a weak signal. We present a theory to account for these results and discuss the biological implications of 1/f noise. copyright 1999 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Chesca, Boris, E-mail: B.Chesca@lboro.ac.uk; John, Daniel [Department of Physics, Loughborough University, Loughborough LE11 3TU (United Kingdom); Mellor, Christopher J. [School of Physics and Astronomy, Nottingham University, Nottingham NG7 2RD (United Kingdom)
2015-10-19
A very promising direction to improve the sensitivity of magnetometers based on superconducting quantum interference devices (SQUIDs) is to build a series-array of N non-interacting SQUIDs operating flux-coherently, because in this case their voltage modulation depth, ΔV, linearly scales with N whereas the white flux noise S{sub Φ}{sup 1/2} decreases as 1/N{sup 1/2}. Here, we report the realization of both these improvements in an advanced layout of very large SQUID arrays made of YBa{sub 2}Cu{sub 3}O{sub 7}. Specially designed with large area narrow flux focusers for increased field sensitivity and improved flux-coherency, our arrays have extremely low values for S{sub Φ}{sup 1/2} between (0.25 and 0.44) μΦ{sub 0}/Hz{sup 1/2} for temperatures in the range (77–83) K. In this respect, they outperform niobium/aluminium trilayer technology-based single-SQUIDs operating at 4.2 K. Moreover, with values for ΔV and transimpedance in the range of (10–17) mV and (0.3–2.5) kΩ, respectively, a direct connection to a low-noise room temperature amplifier is allowed, while matching for such readout is simplified and the available bandwidth is greatly increased. These landmark performances suggest such series SQUID arrays are ideal candidates to replace single-SQUIDs operating at 4.2 K in many applications.
Thermal voltage noise in layered superconductors
International Nuclear Information System (INIS)
Ashkenazy, V.D.; Jung, G.; Shapiro, B.Y.
1995-01-01
Thermal voltage noise in the mixed state of type-II superconductors has been calculated taking into account fluctuation modes of nonrigid vortices. It has been shown that bending of vortices leads to new effects in thermal-voltage-noise spectra at high frequencies. The power spectrum reflecting fluctuations of rigid vortices is suppressed at very low frequencies and saturates into a white spectrum at a characteristic frequency depending on the strip width. At high frequencies tilt modes of flexible vortices start to contribute to the fluctuating voltages and the power spectrum undergoes three subsequent magnitude increases, following ω 1/2 -, ω 2 -, and again ω 1/2 -like behavior before becoming white again. It has been shown that for layered superconductors of a moderate anisotropy the second ω 1/2 -like increase disappears at magnetic fields exceeding a certain threshold field corresponding to the crossover field between two-dimensional and three-dimensional vortex-lattice melting. Field dependencies of characteristic frequencies separating different regimes of spectral behavior have been evaluated and shown to be qualitatively different for low and high magnetic fields
International Nuclear Information System (INIS)
Javadi, H.H.S.; Bowen, J.G.; Rascoe, D.L.; Chorey, C.M.
1996-01-01
A deep space satellite downconverter receiver was proposed by Jet Propulsion Laboratory (JPL) and NASA Lewis Research Center (LeRC) for the Naval Research Laboratory's (NRL) high temperature superconductivity space experiment, phase-II (HTSSE-II) program. Space qualified low-noise cryogenic downconverter receivers utilizing thin-film high temperature superconducting (HTS) passive circuitry and semiconductor active devices were developed and delivered to NRL. The downconverter consists of an HTS preselect filter, a cryogenic low-noise amplifier, a cryogenic mixer, and a cryogenic oscillator with an HTS resonator. HTS components were inserted as the front-end filter and the local oscillator resonator for their superior 77 K performance over the conventional components. The semiconducting low noise amplifier also benefited from cooling to 77 K. The mixer was designed specifically for cryogenic applications and provided low conversion loss and low power consumption. In addition to an engineering model, two space qualified units (qualification, flight) were built and delivered to NRL. Manufacturing, integration and test of the space qualified downconverters adhered to the requirements of JPL class-D space instruments and partially to MIL-STD-883D specifications. The qualification unit has ∼50 K system noise temperature which is a factor of three better than a conventional downconverter at room temperature
International Nuclear Information System (INIS)
Shu Chang-Zheng; Nie Lin-Ru; Zhou Zhong-Rao
2012-01-01
Stochastic resonance (SR)-like and resonance suppression (RS)-like phenomena in a time-delayed bistable system driven by additive white noise are investigated by means of stochastic simulations of the power spectrum, the quality factor of the power spectrum, and the mean first-passage time (MFPT) of the system. The calculative results indicate that: (i) as the system is driven by a small periodic signal, the quality factor as a function delay time exhibits a maximal value at smaller noise intensities, i.e., an SR-like phenomenon. With the increment in additive noise intensity, the extremum gradually disappears and the quality factor decreases monotonously with delay time. (ii) As the additive noise intensity is smaller, the curve of the MFPT with respect to delay time displays a peak, i.e., an RS-like phenomenon. At higher levels of noise, however, the non-monotonic behavior is lost. (general)
Energy Technology Data Exchange (ETDEWEB)
Croome, D J
1977-01-01
This book covers the physics of acoustics necessary to understand the analytical aspects of acoustical design and noise control in buildings. The major part is devoted to the problems of noise and man, and other chapters cover features of noise control in and around buildings. In an introduction, building environmental engineering is dealth with in general terms of architecture, creativity, systms design, etc. Aspects of the acoustical environment, noise sources in buildings, control of airborne and structure-borne noise and acoustical design techniques are covered in Part II. Items include: comfort, physiological response to noise and vibrations, noise criteria, human performance, speech communication, landscaped offices, sound generation by air-conditioning and heating equipment, building structure and noise attenuation, acoustical design. Part III gives some fundamentals of acoustics; mechanical vibration, wave motion, propagation of sound, structure-borne sound, behavior of sound in rooms, transmission of sound through structure. References include lists of British standards and booklets on health and safety at work.
Wild, Emily C.; Hammond, Robert E.
1997-01-01
This report provides the results of a detailed Level II analysis of scour potential at structure ROYATH00920029 on Town Highway 92 crossing the First Branch White River, Royalton, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 101-mi2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge. In the study area, the First Branch White River has an incised, sinuous channel with a slope of approximately 0.001 ft/ft, an average channel top width of 81 ft and an average bank height of 9 ft. The channel bed material ranges from sand to bedrock with a median grain size (D50) of 1.18 mm (0.00347 ft). The geomorphic assessment at the time of the Level I site visit on July 23, 1996 and Level II site visit on June 2, 1995, indicated that the reach was stable. The Town Highway 92 crossing of the First Branch White River is a 59-ft-long, one-lane bridge consisting of a 57-foot steel-stringer span (Vermont Agency of Transportation, written communication, March 23, 1995). The opening length of the structure parallel to the bridge face is 52.2 ft. The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 20 degrees to the opening while the opening-skew-to-roadway is zero degrees. A scour hole 4.0 ft deeper than the
Wild, E.C.; Severance, Timothy
1997-01-01
This report provides the results of a detailed Level II analysis of scour potential at structure TUNBTH00450033 on Town Highway 45 crossing the First Branch White River, Tunbridge, Vermont (figures 1–8). A Level II study is a basic engineering analysis of the site, including a quantitative analysis of stream stability and scour (U.S. Department of Transportation, 1993). Results of a Level I scour investigation also are included in Appendix E of this report. A Level I investigation provides a qualitative geomorphic characterization of the study site. Information on the bridge, gleaned from Vermont Agency of Transportation (VTAOT) files, was compiled prior to conducting Level I and Level II analyses and is found in Appendix D. The site is in the New England Upland section of the New England physiographic province in central Vermont. The 86.4-mi 2 drainage area is in a predominantly rural and forested basin. In the vicinity of the study site, the surface cover is pasture upstream and downstream of the bridge, while woody vegetation sparsely covers the immediate banks. In the study area, the First Branch White River has an incised, sinuous channel with a slope of approximately 0.003 ft/ft, an average channel top width of 68 ft and an average bank height of 7 ft. The channel bed material ranges from sand to gravel with a median grain size (D50) of 27.1 mm (0.089 ft). The geomorphic assessment at the time of the Level I and Level II site visit on October 18, 1995, indicated that the reach was laterally unstable due to a cut-bank present on the upstream right bank and a wide channel bar in the upstream reach. The Town Highway 45 crossing of the First Branch White River is a 67-ft-long, one-lane bridge consisting of one 54-foot timber thru-truss span (Vermont Agency of Transportation, written communication, March 23, 1995). The opening length of the structure parallel to the bridge face is 53.5 ft. The bridge is supported on the right by a vertical, concrete abutment
Functional spaces and operators connected with some L\\'evy noises
Lytvynov, E.
2006-01-01
We review some recent developments in white noise analysis and quantum probability. We pay a special attention to spaces of test and generalized functionals of some L\\'evy white noises, as well as as to the structure of quantum white noise on these spaces.
... Regulated by EPA EPA or a designated Federal agency regulates noise sources, such as rail and motor carriers, low noise emission products, construction equipment, transport equipment, trucks, motorcycles, and the labeling of hearing ...
Bragdon, C. R.
Airport and community land use planning as they relate to airport noise reduction are discussed. Legislation, community relations, and the physiological effect of airport noise are considered. Noise at the Logan, Los Angeles, and Minneapolis/St. Paul airports is discussed.
International Nuclear Information System (INIS)
Richardson, W.J.; Greene, C.R.; Koski, W.R.; Smultea, M.A.; Cameron, G.
1991-10-01
The report concerns the effects of underwater noise from simulated oil production operations on the movements and behavior of bowhead and white whales migrating around northern Alaska in spring. An underwater sound projector suspended from pack ice was used to introduce recorded drilling noise and other test sounds into leads through the pack ice. These sounds were received and measured at various distances to determine the rate of sound attenuation with distance and frequency. The movements and behavior of bowhead and white whales approaching the operating projector were studied by aircraft- and ice-based observers. Some individuals of both species were observed to approach well within the ensonified area. However, behavioral changes and avoidance reactions were evident when the received sound level became sufficiently high. Reactions to aircraft are also discussed
The Impact of Concurrent Noise on Visual Search in Children With ADHD.
Allen, Rosemary; Pammer, Kristen
2015-09-22
The purpose of this study was to investigate the impact of a concurrent "white noise" stimulus on selective attention in children with ADHD. Participants were 33 children aged 7 to 14 years, who had been previously diagnosed with ADHD. All children completed a computer-based conjunction search task under two noise conditions: a classroom noise condition and a classroom noise + white noise condition. The white noise stimulus was sounds of rain, administered using an iPhone application called Sleep Machine. There were no overall differences between conditions for target detection accuracy, mean reaction time (RT), or reaction time variability (SD). The impact of white noise on visual search depended on children's medication status. White noise may improve task engagement for non-medicated children. White noise may be beneficial for task performance when used as an adjunct to medication. © The Author(s) 2015.
Energy Technology Data Exchange (ETDEWEB)
Aoki, H.; Yuzawa, H. [Nikken Sekkei Ltd., Osaka (Japan)
1998-01-05
White Ring is a citizen`s gymnasium used for figure skating and short track speed skating games of 18th Winter Olympic Games in 1998. White Ring is composed of a main-arena and a sub-arena. For the main-arena with an area 41mtimes66m, an ice link can be made by disengaging the potable floor and by flowing brine in the bridged polystyrene pipes embedded in the concrete floor. Due to the fortunate groundwater in this site, well water is used for the outside air treatment energy in 63% during heating and in 35% during cooling. Ammonia is used as a cooling medium for refrigerating facility. For the heating of audience area in the large space, heat load from the outside is reduced by enhancing the heat insulation performance of the roof of arena. The audience seats are locally heated using heaters. For the White Ring, high quality environment is realized for games through various functions of the large-scale roof of the large space. Success of the big event was expected. 15 figs., 4 tabs.
International Nuclear Information System (INIS)
Li Jinghui
2008-01-01
In this paper, an electric system with two dichotomous resistors is investigated. It is shown that this system can display two stochastic resonances, which are the amplitude of the periodic response as the functions of the two dichotomous resistors strengthes respectively. In the limits of Gaussian white noise and shot white noise (i.e., the two noises are both Gaussian white noise or shot white noise), no phenomena of resonance appear. By further study, we find that when the system is with three or more multiplicative telegraphic noises, there are three or more stochastic resonances
International Nuclear Information System (INIS)
Sharma, Raghav; Dürrenfeld, P.; Iacocca, E.; Heinonen, O. G.; Åkerman, J.; Muduli, P. K.
2014-01-01
The frequency noise spectrum of a magnetic tunnel junction based spin torque oscillator is examined where multiple modes and mode-hopping events are observed. The frequency noise spectrum is found to consist of both white noise and 1/f frequency noise. We find a systematic and similar dependence of both white noise and 1/f frequency noise on bias current and the relative angle between the reference and free layers, which changes the effective damping and hence the mode-hopping behavior in this system. The frequency at which the 1/f frequency noise changes to white noise increases as the free layer is aligned away from the anti-parallel orientation w.r.t the reference layer. These results indicate that the origin of 1/f frequency noise is related to mode-hopping, which produces both white noise as well as 1/f frequency noise similar to the case of ring lasers.
Detecting network states in white noise
Czech Academy of Sciences Publication Activity Database
Hlinka, Jaroslav; Hadrava, Michal
2015-01-01
Roč. 16, suppl. 1 (2015), P92 ISSN 1471-2202 R&D Projects: GA ČR GA13-23940S; GA ČR GA13-17187S Institutional support: RVO:67985807 Keywords : neurodynamics * EEG * connectivity * clustering * microstates Subject RIV: FH - Neurology
Audibility of harmonics in periodic "white noise"
Duifhuis, H.
1973-01-01
The finding that spectrally suppressed high harmonics (n>16) in a periodic pulse are perceptible has been related [H. Duifhuis, J. Acoust. Soc. Amer. 48, 888–893 (1970); 49, 1155–1163 (1971)] to the ear's limited resolving power in peripheral frequency analysis. The limited frequency resolution
Audibility of harmonics in 'periodic white noise'
Duifhuis, H.; Tomesen, H.H.
1970-01-01
In a previous article (Duifhuis, 1970) results' concerning the audibility of harmonics in a periodic pulse have been presented. Each of the lower harmonics could be perceived separately, whereas the high harmonics were heard together as one complex signal. High harmonics, however, appeared to be
Clustering of noise-induced oscillations
DEFF Research Database (Denmark)
Sosnovtseva, Olga; Fomin, A I; Postnov, D E
2001-01-01
The subject of our study is clustering in a population of excitable systems driven by Gaussian white noise and with randomly distributed coupling strength. The cluster state is frequency-locked state in which all functional units run at the same noise-induced frequency. Cooperative dynamics...
International Nuclear Information System (INIS)
Baturitsky, M.A.; Reutovich, S.I.; Solomashenko, N.F.
1996-01-01
For pt. I see ibid., vol.378, p.564-569, 1996. New monolithic low-noise process has been developed for simultaneous fabrication of high-speed low-noise 4-terminal and 3-terminal pJFETs and microwave low-noise npn BJTs. A new ion-implanted 4-terminal structure of JFET having 300 MHz cut-off frequency is designed. The process provides direct contact to a top gate and independent access to the top and bottom gates. Application of p-channel implant makes it possible to optimize the JFET pinch-off voltage without deterioration of bipolar transistor characteristics: f T ≥3 GHz, current gain β≥150, R bb' ≤15-40 Ω. (orig.)
National Aeronautics and Space Administration — Aurora Flight Sciences Corporation and partner, Draper Laboratory, propose to develop an on-orbit immuno-based label-free white blood cell counting system using MEMS...
White lines at the Lsub(I), Lsub(II), and Lsub(III) absorption edges of some rare earth compounds
Energy Technology Data Exchange (ETDEWEB)
Garg, K B; Sharma, B K; Jain, D C [Rajasthan Univ., Jaipur (India). Dept. of Physics; Sinha, A I.P. [Banasthali Vidyapeeth (India). Dept. of Chemistry
1980-11-01
The paper reports the appearance of white lines (WLS) at all the three L-absorption edges of the sulfur coordinated thiosalicylic acid compounds of Sm, Tb, and Dy. The profiles of the observed WLS are presented and discussed.
International Nuclear Information System (INIS)
Rodigas, Timothy J.; Arriagada, Pamela; Faherty, Jacqueline K.; Weinberger, Alycia; Butler, R. Paul; Bergeron, P.; Simon, Amélie; Anglada-Escudé, Guillem; Mamajek, Eric E.; Males, Jared R.; Morzinski, Katie; Close, Laird M.; Hinz, Philip M.; Bailey, Jeremy; Tinney, C. G.; Wittenmyer, Rob; Carter, Brad; Jenkins, James S.; Jones, Hugh; O’Toole, Simon
2016-01-01
HD 11112 is an old, Sun-like star that has a long-term radial velocity (RV) trend indicative of a massive companion on a wide orbit. Here we present direct images of the source responsible for the trend using the Magellan Adaptive Optics system. We detect the object (HD 11112B) at a separation of 2.″2 (100 au) at multiple wavelengths spanning 0.6–4 μ m and show that it is most likely a gravitationally bound cool white dwarf. Modeling its spectral energy distribution suggests that its mass is 0.9–1.1 M ⊙ , which corresponds to very high eccentricity, near edge-on orbits from a Markov chain Monte Carlo analysis of the RV and imaging data together. The total age of the white dwarf is >2 σ , which is discrepant with that of the primary star under most assumptions. The problem can be resolved if the white dwarf progenitor was initially a double white dwarf binary that then merged into the observed high-mass white dwarf. HD 11112B is a unique and intriguing benchmark object that can be used to calibrate atmospheric and evolutionary models of cool white dwarfs and should thus continue to be monitored by RV and direct imaging over the coming years.
Energy Technology Data Exchange (ETDEWEB)
Rodigas, Timothy J.; Arriagada, Pamela; Faherty, Jacqueline K.; Weinberger, Alycia; Butler, R. Paul [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States); Bergeron, P.; Simon, Amélie [Département de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, Québec H3C 3J7 (Canada); Anglada-Escudé, Guillem [School of Physics and Astronomy, Queen Mary, University of London, 327 Mile End Road, London (United Kingdom); Mamajek, Eric E. [Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627-0171 (United States); Males, Jared R.; Morzinski, Katie; Close, Laird M.; Hinz, Philip M. [Steward Observatory, The University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Bailey, Jeremy; Tinney, C. G.; Wittenmyer, Rob [Exoplanetary Science at UNSW, School of Physics, UNSW Australia, Sydney, NSW 2052 (Australia); Carter, Brad [Computational Engineering and Science Research Centre, University of Southern Queensland, Springfield, QLD 4300 (Australia); Jenkins, James S. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Las Condes, Santiago (Chile); Jones, Hugh [Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Herts AL10 9AB (United Kingdom); O’Toole, Simon, E-mail: trodigas@carnegiescience.edu [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); and others
2016-11-10
HD 11112 is an old, Sun-like star that has a long-term radial velocity (RV) trend indicative of a massive companion on a wide orbit. Here we present direct images of the source responsible for the trend using the Magellan Adaptive Optics system. We detect the object (HD 11112B) at a separation of 2.″2 (100 au) at multiple wavelengths spanning 0.6–4 μ m and show that it is most likely a gravitationally bound cool white dwarf. Modeling its spectral energy distribution suggests that its mass is 0.9–1.1 M {sub ⊙}, which corresponds to very high eccentricity, near edge-on orbits from a Markov chain Monte Carlo analysis of the RV and imaging data together. The total age of the white dwarf is >2 σ , which is discrepant with that of the primary star under most assumptions. The problem can be resolved if the white dwarf progenitor was initially a double white dwarf binary that then merged into the observed high-mass white dwarf. HD 11112B is a unique and intriguing benchmark object that can be used to calibrate atmospheric and evolutionary models of cool white dwarfs and should thus continue to be monitored by RV and direct imaging over the coming years.
DEFF Research Database (Denmark)
Kærgaard, Kevin; Jensen, Søren Hjøllund; Puthusserypady, Sadasivan
2015-01-01
Electrocardiogram (ECG) is a widely used noninvasive method to study the rhythmic activity of the heart and thereby to detect the abnormalities. However, these signals are often obscured by artifacts from various sources and minimization of these artifacts are of paramount important. This paper...... proposes two adaptive techniques, namely the EEMD-BLMS (Ensemble Empirical Mode Decomposition in conjunction with the Block Least Mean Square algorithm) and DWT-NN (Discrete Wavelet Transform followed by Neural Network) methods in minimizing the artifacts from recorded ECG signals, and compares...... their performance. These methods were first compared on two types of simulated noise corrupted ECG signals: Type-I (desired ECG+noise frequencies outside the ECG frequency band) and Type-II (ECG+noise frequencies both inside and outside the ECG frequency band). Subsequently, they were tested on real ECG recordings...
Directory of Open Access Journals (Sweden)
Rudolf Häusler
2008-06-01
Full Text Available Users of cochlear implants (auditory aids, which stimulate the auditory nerve electrically at the inner ear often suffer from poor speech understanding in noise. We evaluate a small (intermicrophone distance 7Ã¢Â€Â‰mm and computationally inexpensive adaptive noise reduction system suitable for behind-the-ear cochlear implant speech processors. The system is evaluated in simulated and real, anechoic and reverberant environments. Results from simulations show improvements of 3.4 to 9.3Ã¢Â€Â‰dB in signal to noise ratio for rooms with realistic reverberation and more than 18Ã¢Â€Â‰dB under anechoic conditions. Speech understanding in noise is measured in 6 adult cochlear implant users in a reverberant room, showing average improvements of 7.9Ã¢Â€Â“9.6Ã¢Â€Â‰dB, when compared to a single omnidirectional microphone or 1.3Ã¢Â€Â“5.6Ã¢Â€Â‰dB, when compared to a simple directional two-microphone device. Subjective evaluation in a cafeteria at lunchtime shows a preference of the cochlear implant users for the evaluated device in terms of speech understanding and sound quality.
The impact of red noise in radial velocity planet searches: only three planets orbiting GJ 581?
Baluev, Roman V.
2013-03-01
We perform a detailed analysis of the latest HARPS and Keck radial velocity data for the planet-hosting red dwarf GJ 581, which attracted a lot of attention in recent time. We show that these data contain important correlated noise component (`red noise') with the correlation time-scale of the order of 10 d. This red noise imposes a lot of misleading effects while we work in the traditional white-noise model. To eliminate these misleading effects, we propose a maximum-likelihood algorithm equipped by an extended model of the noise structure. We treat the red noise as a Gaussian random process with an exponentially decaying correlation function. Using this method we prove that (i) planets b and c do exist in this system, since they can be independently detected in the HARPS and Keck data, and regardless of the assumed noise models; (ii) planet e can also be confirmed independently by both the data sets, although to reveal it in the Keck data it is mandatory to take the red noise into account; (iii) the recently announced putative planets f and g are likely just illusions of the red noise; (iv) the reality of the planet candidate GJ 581 d is questionable, because it cannot be detected from the Keck data, and its statistical significance in the HARPS data (as well as in the combined data set) drops to a marginal level of ˜2σ, when the red noise is taken into account. Therefore, the current data for GJ 581 really support the existence of no more than four (or maybe even only three) orbiting exoplanets. The planet candidate GJ 581 d requests serious observational verification.
Dynamical reduction models with general gaussian noises
International Nuclear Information System (INIS)
Bassi, Angelo; Ghirardi, GianCarlo
2002-02-01
We consider the effect of replacing in stochastic differential equations leading to the dynamical collapse of the statevector, white noise stochastic processes with non white ones. We prove that such a modification can be consistently performed without altering the most interesting features of the previous models. One of the reasons to discuss this matter derives from the desire of being allowed to deal with physical stochastic fields, such as the gravitational one, which cannot give rise to white noises. From our point of view the most relevant motivation for the approach we propose here derives from the fact that in relativistic models the occurrence of white noises is the main responsible for the appearance of untractable divergences. Therefore, one can hope that resorting to non white noises one can overcome such a difficulty. We investigate stochastic equations with non white noises, we discuss their reduction properties and their physical implications. Our analysis has a precise interest not only for the above mentioned subject but also for the general study of dissipative systems and decoherence. (author)
Stochastic systems driven by alpha-stable noises
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Ditlevsen, P.
1998-01-01
with observed data. In particular the tailsof the observed response distributions may even for linear systems be more fat than the tails obtained for Gaussianwhite noise input. Also the excitation may show jumps that cannot be modeled by Gaussian white noise. The paper supports the possibility of using...... the larger class of so-calledalpha-stable white noises to provide a better fit. A geophysical application concerning ice age climate variations is described....
Electrochemical noise from corroding carbon steel and aluminium
International Nuclear Information System (INIS)
Singh, P.R.; Gaonkar, K.B.; De, P.K.; Banerjee, S.
1997-05-01
Electrochemical noise measurements were conducted on carbon steel and aluminium in sodium chloride solutions. Noise parameters like standard deviation of potential and current, noise resistance, pitting index, noise power were studied for the purpose of measuring corrosion rate. These parameters compared well with the corrosion rate. Pitting index was not very reliable. Current noise was more close to the corrosion rates. General corrosion gave rise to white noise type of power spectrum while flicker noise type of spectrum was obtained from pitting attack. Sodium nitrite is shown to inhibit the corrosion of carbon steel. Aluminium corrodes in the early period of exposure and passivates during long exposure
Oma modal indication by sensitivity to added artificial noise
DEFF Research Database (Denmark)
Juul, Martin O.; Olsen, Peter; Tarpø, Marius
2017-01-01
This paper presents a modal indicator for use in OMA identification techniques relying on the correlation function for extraction of parameters. We propose to add small amounts of artificial white Gaussian noise to the correlation function and measuring the sensitivity of the identified modes...... to this noise. The idea is to identify system parameters many times, each time adding a tiny amount of uncorrelated white Gaussian noise to the correlation function. Since the noise modes are more affected by the adding of tiny amounts of additional noise, than the physical modes, the variance of the estimated...
Trajectories of Brownian particles with space-correlated noise
Indian Academy of Sciences (India)
EDOARDO MILOTTI
walks with spatially correlated white noise: the time- dependence of the distance of pairs of random walkers. ... Dedicated to the memory of the late Professor Charusita Chakravarty. also quite well-known that the two-sided noise .... due to the individual noise components, we find that in the present context the value of ξ2 is.
Xu, Jinghong; Yu, Liping; Zhang, Jiping; Cai, Rui; Sun, Xinde
2010-02-15
Auditory experience during the postnatal critical period is essential for the normal maturation of auditory function. Previous studies have shown that rearing infant rat pups under conditions of continuous moderate-level noise delayed the emergence of adult-like topographic representational order and the refinement of response selectivity in the primary auditory cortex (A1) beyond normal developmental benchmarks and indefinitely blocked the closure of a brief, critical-period window. To gain insight into the molecular mechanisms of these physiological changes after noise rearing, we studied expression of the AMPA receptor subunit GluR2 and GABA(A) receptor subunit beta3 in the auditory cortex after noise rearing. Our results show that continuous moderate-level noise rearing during the early stages of development decreases the expression levels of GluR2 and GABA(A)beta3. Furthermore, noise rearing also induced a significant decrease in the level of GABA(A) receptors relative to AMPA receptors. However, in adult rats, noise rearing did not have significant effects on GluR2 and GABA(A)beta3 expression or the ratio between the two units. These changes could have a role in the cellular mechanisms involved in the delayed maturation of auditory receptive field structure and topographic organization of A1 after noise rearing. Copyright 2009 Wiley-Liss, Inc.
Energy Technology Data Exchange (ETDEWEB)
Zackay, Barak; Ofek, Eran O. [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel)
2017-02-20
Image coaddition is one of the most basic operations that astronomers perform. In Paper I, we presented the optimal ways to coadd images in order to detect faint sources and to perform flux measurements under the assumption that the noise is approximately Gaussian. Here, we build on these results and derive from first principles a coaddition technique that is optimal for any hypothesis testing and measurement (e.g., source detection, flux or shape measurements, and star/galaxy separation), in the background-noise-dominated case. This method has several important properties. The pixels of the resulting coadded image are uncorrelated. This image preserves all the information (from the original individual images) on all spatial frequencies. Any hypothesis testing or measurement that can be done on all the individual images simultaneously, can be done on the coadded image without any loss of information. The PSF of this image is typically as narrow, or narrower than the PSF of the best image in the ensemble. Moreover, this image is practically indistinguishable from a regular single image, meaning that any code that measures any property on a regular astronomical image can be applied to it unchanged. In particular, the optimal source detection statistic derived in Paper I is reproduced by matched filtering this image with its own PSF. This coaddition process, which we call proper coaddition, can be understood as the maximum signal-to-noise ratio measurement of the Fourier transform of the image, weighted in such a way that the noise in the entire Fourier domain is of equal variance. This method has important implications for multi-epoch seeing-limited deep surveys, weak lensing galaxy shape measurements, and diffraction-limited imaging via speckle observations. The last topic will be covered in depth in future papers. We provide an implementation of this algorithm in MATLAB.
Femtosecond photoionization of atoms under noise
International Nuclear Information System (INIS)
Singh, Kamal P.; Rost, Jan M.
2007-01-01
We investigate the effect of incoherent perturbations on atomic photoionization due to a femtosecond midinfrared laser pulse by solving the time-dependent stochastic Schroedinger equation. For a weak laser pulse which causes almost no ionization, an addition of a Gaussian white noise to the pulse leads to a significantly enhanced ionization probability. Tuning the noise level, a stochastic resonancelike curve is observed showing the existence of an optimum noise for a given laser pulse. Besides studying the sensitivity of the obtained enhancement curve on the pulse parameters, such as the pulse duration and peak amplitude, we suggest that experimentally realizable broadband chaotic light can also be used instead of the white noise to observe similar features. The underlying enhancement mechanism is analyzed in the frequency domain by computing a frequency-resolved atomic gain profile, as well as in the time domain by controlling the relative delay between the action of the laser pulse and noise
K. L. Frank; B. W. Geils; L. S. Kalkstein; H. W. Thistle
2008-01-01
An invasive forest pathogen, Cronartium ribicola, white pine blister rust (WPBR), is believed to have arrived in the Sacramento Mountains of south-central New Mexico about 1970. Epidemiological and genetic evidence supports the hypothesis that introduction was the result of long-distance dispersal (LDD) by atmospheric transport from California. This...
International Nuclear Information System (INIS)
Fujimoto, M.Y.
1982-01-01
By means of analytical solutions of the envelope, thermal properties of hydrogen shell burning on accreting white dwarfs are studied and a general picture for their progress is presented which is described by two parameters, the accretion rate and the mass of the white dwarf. On a white dwarf, the thermal behavior of gas in the burning shell depends on the configuration of the envelope, which gives birth to two distinct types of stable configurations in thermal equilibrium, a high and a low state. In the high state, the nuclear shell burning makes up for the energy loss from the surface. There exists the lower limit to the envelope mass for this state. The nuclear burning rate lies in a narrow range of about a factor of 2.5, irrespective of the mass of the white dwarf, while the range itself varies greatly with the latter. In the low state, the nuclear burning is extinct, and yet the compressional heating by accreted gas balances with the cooling through the diffusion of heat. Therefore, the structure depends on the accretion rate. Thermal instability of nuclear burning sets the upper limit to the envelope mass of this state
Schils, R.L.M.; Boxem, T.; Jagtenberg, C.J.; Verboom, M.C.
2000-01-01
The performance of a white clover based dairy system in comparison with a grass/fertiliser-N system was studied during three years. Both systems had 59 cows, plus young stock, on an area of 40.6 ha for grass/clover and 34.4 ha for grass/fertiliser-N. During the grazing season, the cows in both
Lammers, J.H.C.M.; Emmen, H.H.; Muijser, H.; Hoogendijk, E.M.G.; McKee, R.H.; Owen, D.E.; Kulig, B.M.
2007-01-01
To evaluate the neurobehavioral effects of hydrocarbon solvents and to establish a working model for extrapolating animal test data to humans, studies were conducted which involved inhalation exposure of rats and humans to white spirit (WS). The specific objectives of these studies were to evaluate
Tinney, Charles; Sirohi, Jayant; University of Texas at Austin Team
2017-11-01
A basic understanding of the noise produced by single and multirotor drones operating at static thrust conditions is presented. This work acts as an extension to previous efforts conducted at The University of Texas at Austin (Tinney et al. 2017, AHS Forum 73). Propeller diameters ranging from 8 inch to 12 inch are examined for configurations comprising an isolated rotor, a quadcopter configuration and a hexacopter configuration, and with a constant drone pitch of 2.25. An azimuthal array of half-inch microphones, placed between 2 and 3 hub-center diameters from the drone center, are used to assess the acoustic near-field. Thrust levels, acquired using a six degree-of-freedom load cell, are then used to correlate acoustic noise levels to aerodynamic performance for each drone configuration. The findings reveal a nearly logarithmic increase in noise with increasing thrust. However, for the same thrust condition, considerable noise reduction is achieved by increasing the number of propeller blades thereby reducing the blade passage frequency and both the thickness and loading noise sources that accompany it.
Speech production in amplitude-modulated noise
DEFF Research Database (Denmark)
Macdonald, Ewen N; Raufer, Stefan
2013-01-01
The Lombard effect refers to the phenomenon where talkers automatically increase their level of speech in a noisy environment. While many studies have characterized how the Lombard effect influences different measures of speech production (e.g., F0, spectral tilt, etc.), few have investigated...... the consequences of temporally fluctuating noise. In the present study, 20 talkers produced speech in a variety of noise conditions, including both steady-state and amplitude-modulated white noise. While listening to noise over headphones, talkers produced randomly generated five word sentences. Similar...... of noisy environments and will alter their speech accordingly....
Cosmic noise: a history of early radio astronomy
National Research Council Canada - National Science Library
Sullivan, Woodruff Turner
2009-01-01
.... The whole of worldwide radio and radar astronomy is covered, beginning with the discoveries by Jansky and Reber of cosmic noise before World War II, through the wartime detections of solar noise...
Noise in strong laser-atom interactions: Phase telegraph noise
International Nuclear Information System (INIS)
Eberly, J.H.; Wodkiewicz, K.; Shore, B.W.
1984-01-01
We discuss strong laser-atom interactions that are subjected to jump-type (random telegraph) random-phase noise. Physically, the jumps may arise from laser fluctuations, from collisions of various kinds, or from other external forces. Our discussion is carried out in two stages. First, direct and partially heuristic calculations determine the laser spectrum and also give a third-order differential equation for the average inversion of a two-level atom on resonance. At this stage a number of general features of the interaction are able to be studied easily. The optical analog of motional narrowing, for example, is clearly predicted. Second, we show that the theory of generalized Poisson processes allows laser-atom interactions in the presence of random telegraph noise of all kinds (not only phase noise) to be treated systematically, by means of a master equation first used in the context of quantum optics by Burshtein. We use the Burshtein equation to obtain an exact expression for the two-level atom's steady-state resonance fluorescence spectrum, when the exciting laser exhibits phase telegraph noise. Some comparisons are made with results obtained from other noise models. Detailed treatments of the effects ofmly jumps, or as a model of finite laser bandwidth effects, in which the laser frequency exhibits random jumps. We show that these two types of frequency noise can be distinguished in light-scattering spectra. We also discuss examples which demonstrate both temporal and spectral motional narrowing, nonexponential correlations, and non-Lorentzian spectra. Its exact solubility in finite terms makes the frequency-telegraph noise model an attractive alternative to the white-noise Ornstein-Uhlenbeck frequency noise model which has been previously applied to laser-atom interactions
Noise characteristics of neutron images obtained by cooled CCD device
International Nuclear Information System (INIS)
Taniguchi, Ryoichi; Sasaki, Ryoya; Okuda, Shuichi; Okamoto, Ken-Ichi; Ogawa, Yoshihiro; Tsujimoto, Tadashi
2009-01-01
The noise characteristics of a cooled CCD device induced by neutron and gamma ray irradiation have been investigated. In the cooled CCD images, characteristic white spot noises (CCD noise) frequently appeared, which have a shape like a pixel in most cases and their brightness is extremely high compared with that of the image pattern. They could be divided into the two groups, fixed pattern noise (FPN) and random noise. The former always appeared in the same position in the image and the latter appeared at any position. In the background image, nearly all of the CCD noises were found to be the FPN, while many of them were the random noise during the irradiation. The random CCD noises increased with irradiation and decreased soon after the irradiation. In the case of large irradiation, a part of the CCD noise remained as the FPN. These facts suggest that the CCD noise is a phenomenon strongly relating to radiation damage of the CCD device.
Chaos Noise on Phase of Van Der Pol Oscillator
Directory of Open Access Journals (Sweden)
Xian He Huang
2010-12-01
Full Text Available Phase noise is the most important parameter in many oscillators. In this paper, based on nonlinear stochastic differential equation for phase noise analysis approach is proposed. And then discusses and compares the influence of two different sources of noise in the Van Der Pol oscillator adopted this method. One source of noise is a white noise process, which is a genuinely stochastic process; the other source of noise is actually a deterministic system, which exhibits chaotic behavior in some regions. The behavior of the oscillator under different conditions is investigated numerically. It is shown that the phase noise of the oscillator is affected more by noise arising from chaos than by noise arising from the genuine stochastic process at the same noise intensity.
... content Jump to navigation the WHITE HOUSE President Donald J. Trump Get in Touch Home Briefing Room From the ... For All Americans The Administration The Administration President Donald J. Trump Vice President Mike Pence First Lady Melania Trump ...
Statistics of Narrowband White Noise Derived from Clipped Broadband White Noise
1992-02-01
e -26’lnN (7) A=1 with the inverse transform given by I N C(nAt) X D (lAf)e 2N. (8) The validity of this transform pair can be established by means...of the identity N I e (x"- ’ N = 8n.k+IN. (9) NARROWBAND STATISTICS The discrete Fourier transform and inverse transform can be executed via the fast
National Research Council Canada - National Science Library
Michalowicz, Joseph V; Nichols, Jonathan M; Bucholtz, Frank
2008-01-01
Understanding the limitations to detecting deterministic signals in the presence of noise, especially additive, white Gaussian noise, is of importance for the design of LPI systems and anti-LPI signal defense...
Noise-induced effects in population dynamics
Spagnolo, Bernardo; Cirone, Markus; La Barbera, Antonino; de Pasquale, Ferdinando
2002-03-01
We investigate the role of noise in the nonlinear relaxation of two ecosystems described by generalized Lotka-Volterra equations in the presence of multiplicative noise. Specifically we study two cases: (i) an ecosystem with two interacting species in the presence of periodic driving; (ii) an ecosystem with a great number of interacting species with random interaction matrix. We analyse the interplay between noise and periodic modulation for case (i) and the role of the noise in the transient dynamics of the ecosystem in the presence of an absorbing barrier in case (ii). We find that the presence of noise is responsible for the generation of temporal oscillations and for the appearance of spatial patterns in the first case. In the other case we obtain the asymptotic behaviour of the time average of the ith population and discuss the effect of the noise on the probability distributions of the population and of the local field.
Vibration Noise Modeling for Measurement While Drilling System Based on FOGs
Directory of Open Access Journals (Sweden)
Chunxi Zhang
2017-10-01
Full Text Available Aiming to improve survey accuracy of Measurement While Drilling (MWD based on Fiber Optic Gyroscopes (FOGs in the long period, the external aiding sources are fused into the inertial navigation by the Kalman filter (KF method. The KF method needs to model the inertial sensors’ noise as the system noise model. The system noise is modeled as white Gaussian noise conventionally. However, because of the vibration while drilling, the noise in gyros isn’t white Gaussian noise any more. Moreover, an incorrect noise model will degrade the accuracy of KF. This paper developed a new approach for noise modeling on the basis of dynamic Allan variance (DAVAR. In contrast to conventional white noise models, the new noise model contains both the white noise and the color noise. With this new noise model, the KF for the MWD was designed. Finally, two vibration experiments have been performed. Experimental results showed that the proposed vibration noise modeling approach significantly improved the estimated accuracies of the inertial sensor drifts. Compared the navigation results based on different noise model, with the DAVAR noise model, the position error and the toolface angle error are reduced more than 90%. The velocity error is reduced more than 65%. The azimuth error is reduced more than 50%.
Vibration Noise Modeling for Measurement While Drilling System Based on FOGs.
Zhang, Chunxi; Wang, Lu; Gao, Shuang; Lin, Tie; Li, Xianmu
2017-10-17
Aiming to improve survey accuracy of Measurement While Drilling (MWD) based on Fiber Optic Gyroscopes (FOGs) in the long period, the external aiding sources are fused into the inertial navigation by the Kalman filter (KF) method. The KF method needs to model the inertial sensors' noise as the system noise model. The system noise is modeled as white Gaussian noise conventionally. However, because of the vibration while drilling, the noise in gyros isn't white Gaussian noise any more. Moreover, an incorrect noise model will degrade the accuracy of KF. This paper developed a new approach for noise modeling on the basis of dynamic Allan variance (DAVAR). In contrast to conventional white noise models, the new noise model contains both the white noise and the color noise. With this new noise model, the KF for the MWD was designed. Finally, two vibration experiments have been performed. Experimental results showed that the proposed vibration noise modeling approach significantly improved the estimated accuracies of the inertial sensor drifts. Compared the navigation results based on different noise model, with the DAVAR noise model, the position error and the toolface angle error are reduced more than 90%. The velocity error is reduced more than 65%. The azimuth error is reduced more than 50%.
Flicker sensitivity as a function of target area with and without temporal noise.
Rovamo, J; Donner, K; Näsänen, R; Raninen, A
2000-01-01
Flicker sensitivities (1-30 Hz) in foveal, photopic vision were measured as functions of stimulus area with and without strong external white temporal noise. Stimuli were circular, sinusoidally flickering sharp-edged spots of variable diameters (0.25-4 degrees ) but constant duration (2 s), surrounded by a uniform equiluminant field. The data was described with a model comprising (i) low-pass filtering in the retina (R), with a modulation transfer function (MTF) of a form derived from responses of cones; (ii) normalisation of the temporal luminance distribution by the average luminance; (iii) high-pass filtering by postreceptoral neural pathways (P), with an MTF proportional to temporal frequency; (iv) addition of internal white neural noise (N(i)); (v) integration over a spatial window; and (vi) detection by a suboptimal temporal matched filter of efficiency eta. In strong external noise, flicker sensitivity was independent of spot area. Without external noise, sensitivity increased with the square root of stimulus area (Piper's law) up to a critical area (A(c)), where it reaches a maximum level (S(max)). Both A(c) and eta were monotonic functions of temporal frequency (f), such that log A(c) increased and log eta decreased linearly with log f. Remarkably, the increase in spatial integration area and the decrease in efficiency were just balanced, so A(c)(f)eta(f) was invariant against f. Thus the bandpass characteristics of S(max)(f) directly reflected the composite effect of the distal filters R(f) and P(f). The temporal equivalent (N(it)) of internal neural noise (N(i)) decreased in inverse proportion to spot area up to A(c) and then stayed constant indicating that spatially homogeneous signals and noise are integrated over the same area.
Chen, Xue; Huang, Cui; He, Lingmin; Zhang, Shengli; Li, Zengzhi
2015-02-01
The fungal pathogen Beauveria bassiana causes serious economic losses in sericulture. Its origin is usually attributed to the release of B. bassiana insecticides against pine caterpillars (Dendrolimus punctuatus). In the present study, 488 B. bassiana isolates obtained from silkworm (Bombyx mori) collected from 13 Chinese provinces, and 327 B. bassiana isolates obtained from D. punctatus collected from 9 provinces, were analyzed for population genetic structure using the ISSR technique based on genetic distance. A UPGMA dendrogram clustered them into three independent clades: two B. mori clades and one D. punctatus clade. A 3-D principal component analysis further divided them into two completely independent host groups, revealing high host-specificity. This suggested that white muscardine occurring in B. mori populations throughout southern China was not caused by any B. bassiana strain either naturally prevailing in D. punctatus populations or by any strain artificially released as a fungal insecticide against D. punctatus. We further investigated the genetic differentiation coefficient Gst and gene flow between B. mori-pathogenic and D. punctatus-pathogenic B. bassiana isolates from across China and from five provinces inhabited by both B. mori and D. punctatus. The Gst value across China was computed as 0.410, while the values of the five provinces ranged from 0.508 to 0.689; all above 0.25, which is the threshold for significant genetic differentiation. This suggests that B. bassiana strains isolated from the two different hosts maintained their respective heredity without a convergent homogenization trend, and reduces the possibility that the host range of the caterpillar isolates could expand and enhance their virulence in B. mori. These findings indicate that the use of B. bassiana does not threaten the safety of sericulture. Copyright © 2014 Elsevier Inc. All rights reserved.
Theory and Measurement of Signal-to-Noise Ratio in Continuous-Wave Noise Radar.
Stec, Bronisław; Susek, Waldemar
2018-05-06
Determination of the signal power-to-noise power ratio on the input and output of reception systems is essential to the estimation of their quality and signal reception capability. This issue is especially important in the case when both signal and noise have the same characteristic as Gaussian white noise. This article considers the problem of how a signal-to-noise ratio is changed as a result of signal processing in the correlation receiver of a noise radar in order to determine the ability to detect weak features in the presence of strong clutter-type interference. These studies concern both theoretical analysis and practical measurements of a noise radar with a digital correlation receiver for 9.2 GHz bandwidth. Firstly, signals participating individually in the correlation process are defined and the terms signal and interference are ascribed to them. Further studies show that it is possible to distinguish a signal and a noise on the input and output of a correlation receiver, respectively, when all the considered noises are in the form of white noise. Considering the above, a measurement system is designed in which it is possible to represent the actual conditions of noise radar operation and power measurement of a useful noise signal and interference noise signals—in particular the power of an internal leakage signal between a transmitter and a receiver of the noise radar. The proposed measurement stands and the obtained results show that it is possible to optimize with the use of the equipment and not with the complex processing of a noise signal. The radar parameters depend on its prospective application, such as short- and medium-range radar, ground-penetrating radar, and through-the-wall detection radar.
2002-01-01
(Released 19 April 2002) The Science 'White Rock' is the unofficial name for this unusual landform which was first observed during the Mariner 9 mission in the early 1970's. As later analysis of additional data sets would show, White Rock is neither white nor dense rock. Its apparent brightness arises from the fact that the material surrounding it is so dark. Images from the Mars Global Surveyor MOC camera revealed dark sand dunes surrounding White Rock and on the floor of the troughs within it. Some of these dunes are just apparent in the THEMIS image. Although there was speculation that the material composing White Rock could be salts from an ancient dry lakebed, spectral data from the MGS TES instrument did not support this claim. Instead, the White Rock deposit may be the erosional remnant of a previously more continuous occurrence of air fall sediments, either volcanic ash or windblown dust. The THEMIS image offers new evidence for the idea that the original deposit covered a larger area. Approximately 10 kilometers to the southeast of the main deposit are some tiny knobs of similarly bright material preserved on the floor of a small crater. Given that the eolian erosion of the main White Rock deposit has produced isolated knobs at its edges, it is reasonable to suspect that the more distant outliers are the remnants of a once continuous deposit that stretched at least to this location. The fact that so little remains of the larger deposit suggests that the material is very easily eroded and simply blows away. The Story Fingers of hard, white rock seem to jut out like icy daggers across a moody Martian surface, but appearances can be deceiving. These bright, jagged features are neither white, nor icy, nor even hard and rocky! So what are they, and why are they so different from the surrounding terrain? Scientists know that you can't always trust what your eyes see alone. You have to use other kinds of science instruments to measure things that our eyes can
External noise distinguishes attention mechanisms.
Lu, Z L; Dosher, B A
1998-05-01
We developed and tested a powerful method for identifying and characterizing the effect of attention on performance in visual tasks as due to signal enhancement, distractor exclusion, or internal noise suppression. Based on a noisy Perceptual Template Model (PTM) of a human observer, the method adds increasing amounts of external noise (white gaussian random noise) to the visual stimulus and observes the effect on performance of a perceptual task for attended and unattended stimuli. The three mechanisms of attention yield three "signature" patterns of performance. The general framework for characterizing the mechanisms of attention is used here to investigate the attentional mechanisms in a concurrent location-cued orientation discrimination task. Test stimuli--Gabor patches tilted slightly to the right or left--always appeared on both the left and the right of fixation, and varied independently. Observers were cued on each trial to attend to the left, the right, or evenly to both stimuli, and decide the direction of tilt of both test stimuli. For eight levels of added external noise and three attention conditions (attended, unattended, and equal), subjects' contrast threshold levels were determined. At low levels of external noise, attention affected threshold contrast: threshold contrasts for non-attended stimuli were systematically higher than for equal attention stimuli, which were, in turn, higher than for attended stimuli. Specifically, when the rms contrast of the external noise is below 10%, there is a consistent 17% elevation of contrast threshold from attended to unattended condition across all three subjects. For higher levels of external noise, attention conditions did not affect threshold contrast values at all. These strong results are characteristic of a signal enhancement, or equivalently, an internal additive noise reduction mechanism of attention.
DEFF Research Database (Denmark)
Jeppesen, Palle
1997-01-01
Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....
Energy Technology Data Exchange (ETDEWEB)
Jacobs, A. M.; Zingale, M. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Nonaka, A.; Almgren, A. S.; Bell, J. B. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)
2016-08-10
The dynamics of helium shell convection driven by nuclear burning establish the conditions for runaway in the sub-Chandrasekhar-mass, double-detonation model for SNe Ia, as well as for a variety of other explosive phenomena. We explore these convection dynamics for a range of white dwarf core and helium shell masses in three dimensions using the low Mach number hydrodynamics code MAESTRO. We present calculations of the bulk properties of this evolution, including time-series evolution of global diagnostics, lateral averages of the 3D state, and the global 3D state. We find a variety of outcomes, including quasi-equilibrium, localized runaway, and convective runaway. Our results suggest that the double-detonation progenitor model is promising and that 3D dynamic convection plays a key role.
International Nuclear Information System (INIS)
Reach, William T.; Lisse, Carey; Von Hippel, Ted; Mullally, Fergal
2009-01-01
We model the mineralogy and distribution of dust around the white dwarf G29-39 using the infrared spectrum from 1 to 35 μm. The spectral model for G29-38 dust combines a wide range of materials based on spectral studies of comets and debris disks. In order of their contribution to the mid-infrared emission, the most abundant minerals around G29-38 are amorphous carbon (λ || = 5, and the radial density profile ∝r -2.7 ; the total mass of this model disk is 2 x 10 19 g. A physically thin (less than the white dwarf radius) and optically thick disk can contribute to the near-infrared continuum only; such a disk cannot explain the longer-wavelength continuum or strong emission features. The combination of a physically thin, optically thick inner disk and an outer, physically thick and moderately optically thin cloud or disk produces a reasonably good fit to the spectrum and requires only silicates in the outer cloud. We discuss the mineralogical results in comparison to planetary materials. The silicate composition contains minerals found from cometary spectra and meteorites, but Fe-rich pyroxene is more abundant than enstatite (Mg-rich pyroxene) or forsterite (Mg-rich olivine) in G29-38 dust, in contrast to what is found in most comet or meteorite mineralogies. Enstatite meteorites may be the most similar solar system materials to G29-38 dust. Finally, we suggest the surviving core of a h ot Jupiteras an alternative (neither cometary nor asteroidal) origin for the debris, though further theoretical work is needed to determine if this hypothesis is viable.
International Nuclear Information System (INIS)
Luke, P. N.; Amman, M.; Lee, J. S.; Manfredi, P. F.
2000-01-01
Noise in CdZnTe devices with different electrode configurations was investigated. Measurements on devices with guard-ring electrode structures showed that surface leakage current does not produce any significant noise. The parallel white noise component of the devices appeared to be generated by the bulk current alone, even though the surface current was substantially higher. This implies that reducing the surface leakage current of a CdZnTe detector may not necessarily result in a significant improvement in noise performance. The noise generated by the bulk current is also observed to be below full shot noise. This partial suppression of shot noise may be the result of Coulomb interaction between carriers or carrier trapping. Devices with coplanar strip electrodes were observed to produce a 1/f noise term at the preamplifier output. Higher levels of this 1/f noise were observed with decreasing gap widths between electrodes. The level of this 1/f noise appeared to be independent of bias voltage and leakage current but was substantially reduced after certain surface treatments
Noise pollution resources compendium
1973-01-01
Abstracts of reports concerning noise pollution are presented. The abstracts are grouped in the following areas of activity: (1) sources of noise, (2) noise detection and measurement, (3) noise abatement and control, (4) physical effects of noise and (5) social effects of noise.
Yesterday's noise - today's signal
International Nuclear Information System (INIS)
Serdula, K.J.
1978-01-01
Plant performance can be improved by noise analysis. This paper describes noise characteristics, imposed noise and response functions, a case history of cost benefits derived from application of noise analysis techniques, areas for application of noise analysis techniques with special reference to the Gentilly-1 nuclear generating station, and the validity of noise measurement results. (E.C.B.)
DEFF Research Database (Denmark)
Jørholt, Eva
2017-01-01
Inspired by Alain Robbe-Grillet’s novel La Jalousie (1957), the essay contends that Michael Haneke’s Caché (2005) takes its viewers inside a postcolonial white paranoia which is, arguably, the root cause of the exclusion, segregation and racist discrimination that many immigrants from the former ...
DEFF Research Database (Denmark)
Blaagaard, Bolette
2008-01-01
Born out of the United States’ (U.S.) history of slavery and segregation and intertwined with gender studies and feminism, the field of critical whiteness studies does not fit easily into a European setting and the particular historical context that entails. In order for a field of European...
Modelling of excess noise attnuation by grass and forest | Onuu ...
African Journals Online (AJOL)
, guinea grass (panicum maximum) and forest which comprises iroko (milicia ezcelea) and white afara (terminalia superba) trees in the ratio of 2:1 approximately. Excess noise attenuation spectra have been plotted for the grass and forest for ...
Listen to the noise: noise is beneficial for cognitive performance in ADHD.
Söderlund, Göran; Sikström, Sverker; Smart, Andrew
2007-08-01
Noise is typically conceived of as being detrimental to cognitive performance. However, given the mechanism of stochastic resonance, a certain amount of noise can benefit performance. We investigate cognitive performance in noisy environments in relation to a neurocomputational model of attention deficit hyperactivity disorder (ADHD) and dopamine. The Moderate Brain Arousal model (MBA; Sikström & Söderlund, 2007) suggests that dopamine levels modulate how much noise is required for optimal cognitive performance. We experimentally examine how ADHD and control children respond to different encoding conditions, providing different levels of environmental stimulation. Participants carried out self-performed mini tasks (SPT), as a high memory performance task, and a verbal task (VT), as a low memory task. These tasks were performed in the presence, or absence, of auditory white noise. Noise exerted a positive effect on cognitive performance for the ADHD group and deteriorated performance for the control group, indicating that ADHD subjects need more noise than controls for optimal cognitive performance. The positive effect of white noise is explained by the phenomenon of stochastic resonance (SR), i.e., the phenomenon that moderate noise facilitates cognitive performance. The MBA model suggests that noise in the environment, introduces internal noise into the neural system through the perceptual system. This noise induces SR in the neurotransmitter systems and makes this noise beneficial for cognitive performance. In particular, the peak of the SR curve depends on the dopamine level, so that participants with low dopamine levels (ADHD) require more noise for optimal cognitive performance compared to controls.
Ruffoli, R; Carpi, A; Giambelluca, M A; Grasso, L; Scavuzzo, M C; Giannessi F, F
2006-10-01
Lipofuscin is an autofluorescent and undegradable material, which accumulates in tissues during ageing and under different types of stress. Among these, oxidative stress represents a major trigger for lipofuscin formation. However, prolonged noise exposure is also an effective stressful stimuli. Diazepam may inhibit lipofuscinogenesis in liver and prevent the noise-induced reduction of the steroidogenesis in the adrenal gland. The aim of the study was to ascertain whether chronic noise exposure causes lipofuscin accumulation in mouse testis, and to evaluate the effects of diazepam administration. Eight-week old mice were either exposed for 6 weeks (6 h day(-1)) to white-noise (group A), or received diazepam (3 mg kg(-1), i.p.) before noise exposures (group B), while a further group was used as control (group C). Light fluorescence and transmission electron microscopy revealed lipofuscin in large amounts in the Leydig cells in mice of group A, which concomitantly had low serum testosterone levels; pre-treatment with diazepam occluded both effects. The present study indicates that: (i) chronic noise exposure causes lipofuscin accumulation at the level of the Leydig cells and a decrease in testosterone; (ii) all these effects are suppressed by pre-treatment with diazepam. As the Leydig cells represent the only cellular type of the interstitial testicular tissue having peripheral benzodiazepine receptors, these results could be explained by the capacity of the peripheral benzodiazepine receptors to prevent reactive oxygen species damage and to increase the resistance of these cells to oxidative stress.
Research on the Method of Noise Error Estimation of Atomic Clocks
Song, H. J.; Dong, S. W.; Li, W.; Zhang, J. H.; Jing, Y. J.
2017-05-01
The simulation methods of different noises of atomic clocks are given. The frequency flicker noise of atomic clock is studied by using the Markov process theory. The method for estimating the maximum interval error of the frequency white noise is studied by using the Wiener process theory. Based on the operation of 9 cesium atomic clocks in the time frequency reference laboratory of NTSC (National Time Service Center), the noise coefficients of the power-law spectrum model are estimated, and the simulations are carried out according to the noise models. Finally, the maximum interval error estimates of the frequency white noises generated by the 9 cesium atomic clocks have been acquired.
International Nuclear Information System (INIS)
Beenakker, C W J
2005-01-01
Quantum Noise is advertised as a handbook, and this is indeed how it functions for me these days: it is a book that I keep within hand's reach, ready to be consulted on the proper use of quantum stochastic methods in the course of my research on quantum dots. I should point out that quantum optics, the target field for this book, is not my field by training. So I have much to learn, and find this handbook to be a reliable and helpful guide. Crispin Gardiner previously wrote the Handbook of Stochastic Methods (also published by Springer), which provides an overview of methods in classical statistical physics. Quantum Noise, written jointly with Peter Zoller, is the counterpart for quantum statistical physics, and indeed the two books rely on each other by frequent cross referencing. The fundamental problem addressed by Quantum Noise is how the quantum dynamics of an open system can be described statistically by treating the environment as a source of noise. This is a general problem in condensed matter physics (in particular in the context of Josephson junctions) and in quantum optics. The emphasis in this book in on the optical applications (for condensed matter applications one could consult Quantum Dissipative Systems by Ulrich Weiss, published by World Scientific). The optical applications centre around the interaction of light with atoms, where the atoms represent the open system and the light is the noisy environment. A complete description of the production and detection of non-classical states of radiation (such as squeezed states) can be obtained using one of the equivalent quantum stochastic formulations: the quantum Langevin equation for the field operators (in either the Ito or the Stratonovich form), the Master equation for the density matrix, or the stochastic Schroedinger equation for the wave functions. Each formulation is fully developed here (as one would expect from a handbook), with detailed instructions on how to go from one to the other. The
Stochastic memory: getting memory out of noise
Stotland, Alexander; di Ventra, Massimiliano
2011-03-01
Memory circuit elements, namely memristors, memcapacitors and meminductors, can store information without the need of a power source. These systems are generally defined in terms of deterministic equations of motion for the state variables that are responsible for memory. However, in real systems noise sources can never be eliminated completely. One would then expect noise to be detrimental for memory. Here, we show that under specific conditions on the noise intensity memory can actually be enhanced. We illustrate this phenomenon using a physical model of a memristor in which the addition of white noise into the state variable equation improves the memory and helps the operation of the system. We discuss under which conditions this effect can be realized experimentally, discuss its implications on existing memory systems discussed in the literature, and also analyze the effects of colored noise. Work supported in part by NSF.
Noise-driven phenomena in hysteretic systems
Dimian, Mihai
2014-01-01
Noise-Driven Phenomena in Hysteretic Systems provides a general approach to nonlinear systems with hysteresis driven by noisy inputs, which leads to a unitary framework for the analysis of various stochastic aspects of hysteresis. This book includes integral, differential and algebraic models that are used to describe scalar and vector hysteretic nonlinearities originating from various areas of science and engineering. The universality of the authors approach is also reflected by the diversity of the models used to portray the input noise, from the classical Gaussian white noise to its impulsive forms, often encountered in economics and biological systems, and pink noise, ubiquitous in multi-stable electronic systems. The book is accompanied by HysterSoft© - a robust simulation environment designed to perform complex hysteresis modeling – that can be used by the reader to reproduce many of the results presented in the book as well as to research both disruptive and constructive effects of noise in hysteret...
Energy Technology Data Exchange (ETDEWEB)
Von Brixy, H. [Forschungszentrum Juelich GmbH (Germany); Kakuta, Tsunemi
1996-03-01
The noise thermometry (NT) is a temperature measuring method by which the absolute temperature measurement can be performed with a very high accuracy and without any influence of ambient environments and of the thermal history of its NT sensor (electric resistor). Hence it is quite suitable for application as a standard thermometry to the in-situ temperature calibration of incore thermocouples. The KFA Juelich had played a pioneering role in the development of NT and applied the results successfully to the AVR for testing its feasibility. In this report, all about the NT including its principle, sensor elements and system configurations are presented together with the experiences in the AVR and the results of investigation to apply it to high temperature measurement. The NT can be adopted as a standard method for incore temperature measurement and in situ temperature calibration in the HTTR. (author). 85 refs.
International Nuclear Information System (INIS)
Von Brixy, H.; Kakuta, Tsunemi.
1996-03-01
The noise thermometry (NT) is a temperature measuring method by which the absolute temperature measurement can be performed with a very high accuracy and without any influence of ambient environments and of the thermal history of its NT sensor (electric resistor). Hence it is quite suitable for application as a standard thermometry to the in-situ temperature calibration of incore thermocouples. The KFA Juelich had played a pioneering role in the development of NT and applied the results successfully to the AVR for testing its feasibility. In this report, all about the NT including its principle, sensor elements and system configurations are presented together with the experiences in the AVR and the results of investigation to apply it to high temperature measurement. The NT can be adopted as a standard method for incore temperature measurement and in situ temperature calibration in the HTTR. (author). 85 refs
Noise in ecosystems: a short review.
Spagnolo, B; Valenti, D; Fiasconaro, A
2004-06-01
Noise, through its interaction with the nonlinearity of the living systems, can give rise to counter-intuitive phenomena such as stochastic resonance, noise-delayed extinction, temporal oscillations, and spatial patterns. In this paper we briefly review the noise-induced effects in three different ecosystems: (i) two competing species; (ii) three interacting species, one predator and two preys, and (iii) N-interacting species. The transient dynamics of these ecosystems are analyzed through generalized Lotka-Volterra equations in the presence of multiplicative noise, which models the interaction between the species and the environment. The interaction parameter between the species is random in cases (i) and (iii), and a periodical function, which accounts for the environmental temperature, in case (ii). We find noise-induced phenomena such as quasi-deterministic oscillations, stochastic resonance, noise-delayed extinction, and noise-induced pattern formation with nonmonotonic behaviors of patterns areas and of the density correlation as a function of the multiplicative noise intensity. The asymptotic behavior of the time average of the i(th) population when the ecosystem is composed of a great number of interacting species is obtained and the effect of the noise on the asymptotic probability distributions of the populations is discussed.
Noise properties of Hilbert transform evaluation
Czech Academy of Sciences Publication Activity Database
Pavlíček, Pavel; Svak, V.
2015-01-01
Roč. 26, č. 8 (2015), s. 085207 ISSN 0957-0233 R&D Projects: GA ČR GA13-12301S Institutional support: RVO:68378271 Keywords : Hilbert transform * noise * measurement uncertainty * white -light interferometry * fringe-pattern analysis Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.492, year: 2015
Trajectories of Brownian particles with space-correlated noise
Indian Academy of Sciences (India)
Spatial correlations of the noise are usually ruled out, and the paths traced by the random walkers are statistically independent. In this study, I consider instead noise which is white in time and has a Gaussian correlation in space, and by means of numerical simulation, I show how the spatial correlation determines the time ...
Batho, Lauren P; Martinussen, Rhonda; Wiener, Judith
2015-07-28
To examine the effects of environmental noises (speech and white noise) relative to a no noise control condition on the performance and difficulty ratings of youth with ADHD (N = 52) on academic tasks. Reading performance was measured by an oral retell (reading accuracy) and the time spent reading. Writing performance was measured through the proportion of correct writing sequences (writing accuracy) and the total words written on an essay. Participants in the white noise condition took less time to read the passage and wrote more words on the essay compared with participants in the other conditions, though white noise did not improve academic accuracy. The participants in the babble condition rated the tasks as most difficult. Although white noise appears to improve reading time and writing fluency, the findings suggest that white noise does not improve performance accuracy. Educational implications are discussed. © 2015 SAGE Publications.
Dynamical reduction models with general Gaussian noises
International Nuclear Information System (INIS)
Bassi, Angelo; Ghirardi, GianCarlo
2002-01-01
We consider the effect of replacing in stochastic differential equations leading to the dynamical collapse of the state vector, white-noise stochastic processes with nonwhite ones. We prove that such a modification can be consistently performed without altering the most interesting features of the previous models. One of the reasons to discuss this matter derives from the desire of being allowed to deal with physical stochastic fields, such as the gravitational one, which cannot give rise to white noises. From our point of view, the most relevant motivation for the approach we propose here derives from the fact that in relativistic models intractable divergences appear as a consequence of the white nature of the noises. Therefore, one can hope that resorting to nonwhite noises, one can overcome such a difficulty. We investigate stochastic equations with nonwhite noises, we discuss their reduction properties and their physical implications. Our analysis has a precise interest not only for the above-mentioned subject but also for the general study of dissipative systems and decoherence
The Realistic Versus the Spherical Head Model in EEG Dipole Source Analysis in the Presence of Noise
National Research Council Canada - National Science Library
Vanrumste, Bart
2001-01-01
.... For 27 electrodes, an EEG epoch of one time sample and spatially white Gaussian noise we found that the importance of the realistic head model over the spherical head model reduces by increasing the noise level.
Directory of Open Access Journals (Sweden)
Alain Destexhe
2010-03-01
Full Text Available Cortical neurons in vivo may operate in high-conductance states, in which the major part of the neuron's input conductance is due to synaptic activity, sometimes several-fold larger than the resting conductance. We examine here the contribution of inhibition in such high-conductance states. At the level of the absolute conductance values, several studies have shown that cortical neurons in vivo are characterized by strong inhibitory conductances. However, conductances are balanced and spiking activity is mostly determined by fluctuations, but not much is known about excitatory and inhibitory contributions to these fluctuations. Models and dynamic-clamp experiments show that, during high-conductance states, spikes are mainly determined by fluctuations of inhibition, or by inhibitory noise. This stands in contrast to low-conductance states, in which excitatory conductances determine spiking activity. To determine these contributions from experimental data, maximum likelihood methods can be designed and applied to intracellular recordings in vivo. Such methods indicate that action potentials are indeed mostly correlated with inhibitory fluctuations in awake animals. These results argue for a determinant role for inhibitory fluctuations in evoking spikes, and do not support feed-forward modes of processing, for which opposite patterns are predicted.
... ENTCareers Marketplace Find an ENT Doctor Near You Noise and Hearing Protection Noise and Hearing Protection Patient ... it is. How can I tell if a noise is dangerous? People differ in their sensitivity to ...
Theory of fluctuations and parametric noise in a point nuclear reactor model
International Nuclear Information System (INIS)
Rodriguez, M.A.; San Miguel, M.; Sancho, J.M.
1984-01-01
We present a joint description of internal fluctuations and parametric noise in a point nuclear reactor model in which delayed neutrons and a detector are considered. We obtain kinetic equations for the first moments and define effective kinetic parameters which take into account the effect of parametric Gaussian white noise. We comment on the validity of Langevin approximations for this problem. We propose a general method to deal with weak but otherwise arbitrary non-white parametric noise. Exact kinetic equations are derived for Gaussian non-white noise. (author)
Noise and time delay induce critical point in a bistable system
Zhang, Jianqiang; Nie, Linru; Yu, Lilong; Zhang, Xinyu
2014-07-01
We study relaxation time Tc of time-delayed bistable system driven by two cross-correlated Gaussian white noises that one is multiplicative and the other is additive. By means of numerical calculations, the results indicate that: (i) Combination of noise and time delay can induce two critical points about the relaxation time at some certain noise cross-correlation strength λ under the condition that the multiplicative intensity D equals to the additive noise intensity α. (ii) For each fixed D or α, there are two symmetrical critical points which locates in the regions of positive and negative correlations, respectively. Namely, as λ equals to the critical value λc, Tc is independent of the delay time and the result of Tc versus τ is a horizontal line, but as |λ|>|λc| (or |λ|decreases) with the delay time increasing. (iii) In the presence of D = α, the change of λc with D is two symmetrical curves about the axis of λc = 0, and the critical value λc is close to zero for a smaller D, which approaches to +1 or -1 for a greater D.
Stochastic resonance in a stochastic bistable system with additive noises and square–wave signal
International Nuclear Information System (INIS)
Feng, Guo; Xiang-Dong, Luo; Shao-Fu, Li; Yu-Rong, Zhou
2010-01-01
This paper considers the stochastic resonance in a stochastic bistable system driven by a periodic square-wave signal and a static force as well as by additive white noise and dichotomous noise from the viewpoint of signal-to-noise ratio. It finds that the signal-to-noise ratio appears as stochastic resonance behaviour when it is plotted as a function of the noise strength of the white noise and dichotomous noise, as a function of the system parameters, or as a function of the static force. Moreover, the influence of the strength of the stochastic potential force and the correlation rate of the dichotomous noise on the signal-to-noise ratio is investigated. (general)
Rauch, T.; Werner, K.; Quinet, P.; Kruk, J. W.
2014-04-01
Context. For the spectral analysis of high-resolution and high-signal-to-noise (S/N) spectra of hot stars, state-of-the-art non-local thermodynamic equilibrium (NLTE) model atmospheres are mandatory. These are strongly dependent on the reliability of the atomic data that is used for their calculation. In a recent analysis of the ultraviolet (UV) spectrum of the DA-type white dwarf G191-B2B, 21 Zn iv lines were newly identified. Because of the lack of Zn iv data, transition probabilities of the isoelectronic Ge vi were adapted for a first, coarse determination of the photospheric Zn abundance. Aims: Reliable Zn iv and Zn v oscillator strengths are used to improve the Zn abundance determination and to identify more Zn lines in the spectra of G191-B2B and the DO-type white dwarf RE 0503-289. Methods: We performed new calculations of Zn iv and Zn v oscillator strengths to consider their radiative and collisional bound-bound transitions in detail in our NLTE stellar-atmosphere models for the analysis of the Zn iv - v spectrum exhibited in high-resolution and high-S/N UV observations of G191-B2B and RE 0503-289. Results: In the UV spectrum of G191-B2B, we identify 31 Zn iv and 16 Zn v lines. Most of these are identified for the first time in any star. We can reproduce well almost all of them at log Zn = -5.52 ± 0.2 (mass fraction, about 1.7 times solar). In particular, the Zn iv / Zn v ionization equilibrium, which is a very sensitive Teff indicator, is well reproduced with the previously determined and log g = 7.60 ± 0.05. In the spectrum of RE 0503-289, we identified 128 Zn v lines for the first time and determined log Zn = -3.57 ± 0.2 (155 times solar). Conclusions: Reliable measurements and calculations of atomic data are a pre-requisite for stellar-atmosphere modeling. Observed Zn iv and Zn v line profiles in two white dwarf (G191-B2B and RE 0503-289) ultraviolet spectra were well reproduced with our newly calculated oscillator strengths. This allowed us to
1/fα fractal noise generation from Gruenwald-Letnikov formula
International Nuclear Information System (INIS)
Rodriguez, Eduardo; Echeverria, Juan Carlos; Alvarez-Ramirez, Jose
2009-01-01
This communication presents a recursive algorithm for generating streams of 1/f α fractal noise, by means of fractional integration/differentiation of a white noise signal. The quality of correlated and anticorrelated noise obtained by this approach is evaluated by applying detrended fluctuation analysis.
Reduction of environmental MHz noise for SQUID application
Energy Technology Data Exchange (ETDEWEB)
Araya, T. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: araya@sup.ee.es.osaka-u.ac.jp; Kitamura, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Kamishiro, M. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Sakuta, K. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Itozaki, H. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: itozaki@ee.es.osaka-u.ac.jp
2006-10-01
It is important to remove large environmental noise in measurement using SQUIDs without magnetic shielding. Active noise control (ANC) is an effective method to remove the environmental noise. The environmental noise has been reduced by the ANC system in the radio frequency region around MHz. The anti-phase waves of the environmental noise should be generated by this system. The ANC system including the phase and amplitude control circuit was developed to make the anti-phase waves in the MHz region. In this paper, sinusoidal waves with a MHz frequency were used as the environmental noise. When a coil antenna was used for a receiver antenna, this ANC system suppressed these sinusoidal waves to the white noise level about 40 dB. When we used a SQUID as a receiver antenna, we also cancelled sinusoidal waves to the white noise level by this system. This shows that the ANC system is useful to reduce an environmental noise when this ANC system is developed to cancel multi-frequency noise.
Reduction of environmental MHz noise for SQUID application
International Nuclear Information System (INIS)
Araya, T.; Kitamura, Y.; Kamishiro, M.; Sakuta, K.; Itozaki, H.
2006-01-01
It is important to remove large environmental noise in measurement using SQUIDs without magnetic shielding. Active noise control (ANC) is an effective method to remove the environmental noise. The environmental noise has been reduced by the ANC system in the radio frequency region around MHz. The anti-phase waves of the environmental noise should be generated by this system. The ANC system including the phase and amplitude control circuit was developed to make the anti-phase waves in the MHz region. In this paper, sinusoidal waves with a MHz frequency were used as the environmental noise. When a coil antenna was used for a receiver antenna, this ANC system suppressed these sinusoidal waves to the white noise level about 40 dB. When we used a SQUID as a receiver antenna, we also cancelled sinusoidal waves to the white noise level by this system. This shows that the ANC system is useful to reduce an environmental noise when this ANC system is developed to cancel multi-frequency noise
International Nuclear Information System (INIS)
Morishima, N.
1996-01-01
The multivariate autoregressive (MAR) modeling of a vector noise process is discussed in terms of the estimation of dominant noise sources in BWRs. The discussion is based on a physical approach: a transfer function model on BWR core dynamics is utilized in developing a noise model; a set of input-output relations between three system variables and twelve different noise sources is obtained. By the least-square fitting of a theoretical PSD on neutron noise to an experimental one, four kinds of dominant noise sources are selected. It is shown that some of dominant noise sources consist of two or more different noise sources and have the spectral properties of being coloured and correlated with each other. By diagonalizing the PSD matrix for dominant noise sources, we may obtain an MAR expression for a vector noise process as a response to the diagonal elements(i.e. residual noises) being white and mutually-independent. (Author)
Investigations of internal noise levels for different target sizes, contrasts, and noise structures
Han, Minah; Choi, Shinkook; Baek, Jongduk
2014-03-01
To describe internal noise levels for different target sizes, contrasts, and noise structures, Gaussian targets with four different sizes (i.e., standard deviation of 2,4,6 and 8) and three different noise structures(i.e., white, low-pass, and highpass) were generated. The generated noise images were scaled to have standard deviation of 0.15. For each noise type, target contrasts were adjusted to have the same detectability based on NPW, and the detectability of CHO was calculated accordingly. For human observer study, 3 trained observers performed 2AFC detection tasks, and correction rate, Pc, was calculated for each task. By adding proper internal noise level to numerical observer (i.e., NPW and CHO), detectability of human observer was matched with that of numerical observers. Even though target contrasts were adjusted to have the same detectability of NPW observer, detectability of human observer decreases as the target size increases. The internal noise level varies for different target sizes, contrasts, and noise structures, demonstrating different internal noise levels should be considered in numerical observer to predict the detection performance of human observer.
Analytical expressions for transition edge sensor excess noise models
International Nuclear Information System (INIS)
Brandt, Daniel; Fraser, George W.
2010-01-01
Transition edge sensors (TESs) are high-sensitivity thermometers used in cryogenic microcalorimeters which exploit the steep gradient in resistivity with temperature during the superconducting phase transition. Practical TES devices tend to exhibit a white noise of uncertain origin, arising inside the device. We discuss two candidate models for this excess noise, phase slip shot noise (PSSN) and percolation noise. We extend the existing PSSN model to include a magnetic field dependence and derive a basic analytical model for percolation noise. We compare the predicted functional forms of the noise current vs. resistivity curves of both models with experimental data and provide a set of equations for both models to facilitate future experimental efforts to clearly identify the source of excess noise.
Tunable Interior Rotorcraft Noise Control, Phase II
National Aeronautics and Space Administration — CRG has recently developed a new class of shape memory polymers (SMP) that are electrically activated, as opposed to the more mature thermally activated SMPs....
Active Noise Control for Dishwasher noise
Lee, Nokhaeng; Park, Youngjin
2016-09-01
The dishwasher is a useful home appliance and continually used for automatically washing dishes. It's commonly placed in the kitchen with built-in style for practicality and better use of space. In this environment, people are easily exposed to dishwasher noise, so it is an important issue for the consumers, especially for the people living in open and narrow space. Recently, the sound power levels of the noise are about 40 - 50 dBA. It could be achieved by removal of noise sources and passive means of insulating acoustical path. For more reduction, such a quiet mode with the lower speed of cycle has been introduced, but this deteriorates the washing capacity. Under this background, we propose active noise control for dishwasher noise. It is observed that the noise is propagating mainly from the lower part of the front side. Control speakers are placed in the part for the collocation. Observation part of estimating sound field distribution and control part of generating the anti-noise are designed for active noise control. Simulation result shows proposed active noise control scheme could have a potential application for dishwasher noise reduction.
Noise adaptation in integrate-and fire neurons.
Rudd, M E; Brown, L G
1997-07-01
The statistical spiking response of an ensemble of identically prepared stochastic integrate-and-fire neurons to a rectangular input current plus gaussian white noise is analyzed. It is shown that, on average, integrate-and-fire neurons adapt to the root-mean-square noise level of their input. This phenomenon is referred to as noise adaptation. Noise adaptation is characterized by a decrease in the average neural firing rate and an accompanying decrease in the average value of the generator potential, both of which can be attributed to noise-induced resets of the generator potential mediated by the integrate-and-fire mechanism. A quantitative theory of noise adaptation in stochastic integrate-and-fire neurons is developed. It is shown that integrate-and-fire neurons, on average, produce transient spiking activity whenever there is an increase in the level of their input noise. This transient noise response is either reduced or eliminated over time, depending on the parameters of the model neuron. Analytical methods are used to prove that nonleaky integrate-and-fire neurons totally adapt to any constant input noise level, in the sense that their asymptotic spiking rates are independent of the magnitude of their input noise. For leaky integrate-and-fire neurons, the long-run noise adaptation is not total, but the response to noise is partially eliminated. Expressions for the probability density function of the generator potential and the first two moments of the potential distribution are derived for the particular case of a nonleaky neuron driven by gaussian white noise of mean zero and constant variance. The functional significance of noise adaptation for the performance of networks comprising integrate-and-fire neurons is discussed.
Effect of Correlated Noises in a Genetic Model
International Nuclear Information System (INIS)
Li, Zhang; Li, Cao
2010-01-01
The Stratonovich stochastic differential equation is used to analyze genotype selection in the presence of correlated Gaussian white noises. We study the steady state properties of the genotype selection and discuss the effects of the correlated noises. It is found that the degree of correlation of the noises can be used to select one type of genes from another type of mixing genes. The strong selection of genes caused by a large value of multiplicative noise intensity can be weakened by the intensive negative correlation. (general)
Low frequency noise in resonant Josephson soliton oscillators
DEFF Research Database (Denmark)
Hansen, Jørn Bindslev; Holst, T.; Wellstood, Frederick C.
1991-01-01
The noise in the resonant soliton mode of long and narrow Josephson tunnel junctions (Josephson transmission lines or JTLs) have been measured in the frequency range from 0.1 Hz to 25 kHz by means of a DC SQUID. The measured white noise was found, to within a factor of two, to be equal...... to the Nyquist voltage noise in a resistance equal to the dynamic resistance RD of the current-voltage characteristic of the bias point. In contrast, measurements of the linewidth of the microwave radiation from the same JTL showed that the spectral density of the underlying noise voltage scaled as R D2/RS where...
Stochastic memory: Memory enhancement due to noise
Stotland, Alexander; di Ventra, Massimiliano
2012-01-01
There are certain classes of resistors, capacitors, and inductors that, when subject to a periodic input of appropriate frequency, develop hysteresis loops in their characteristic response. Here we show that the hysteresis of such memory elements can also be induced by white noise of appropriate intensity even at very low frequencies of the external driving field. We illustrate this phenomenon using a physical model of memory resistor realized by TiO2 thin films sandwiched between metallic electrodes and discuss under which conditions this effect can be observed experimentally. We also discuss its implications on existing memory systems described in the literature and the role of colored noise.
Narrative Constructions of Whiteness among White Undergraduates
Foste, Zak
2017-01-01
This critical narrative inquiry was guided by two overarching research questions. First, this study examined how white undergraduates interpreted and gave meaning to their white racial identities. This line of inquiry sought to understand how participants made sense of their white racial selves, the self in relation to people of color, and the…
Beam energy gain fluctuation in a linac caused by RF system noise
International Nuclear Information System (INIS)
Sakaki, H.; Yoshikawa, H.; Hori, T.; Yokomizo, H.
2002-01-01
In this paper, energy gain fluctuation caused by white noise in a linear accelerator is calculated. First, we formulate a computational procedure to determine the energy gain in the acceleration structure. Then, using this computational procedure, the size of the white noise of the gain is calculated. These noise sources are caused by various RF components, especially the thyratron. The calculated gain fluctuation per one RF system is ±0.054%∼±0.134%(±3σ). In general, it is difficult to control white noise. This gain fluctuation is composed only of the white noise. Therefore, this value has the same meaning as a 'Control threshold'. Thus, the control method can be evaluated based on this value
Van der Gugten, J; Slangen, J L; de Boer, S.F.
1989-01-01
Plasma noradrenaline (NA), adrenaline (A) and corticosterone (CS) increases were determined in individual rats subjected to either 20 regularly or irregularly scheduled white-noise stimulations (4 min, 100 dBA). Blood was frequently sampled during the first and twentieth noise exposure, and during a reexposure after 24 hr. During the sampling periods, behavioral activities of the rats were recorded. The initial noise-induced CS release was partially reduced following the regular noise present...
Noise-Induced Transition in a Voltage-Controlled Oscillator Neuron Model
International Nuclear Information System (INIS)
Xie Huizhang; Liu Xuemei; Li Zhibing; Ai Baoquan; Liu Lianggang
2008-01-01
In the presence of Gaussian white noise, we study the properties of voltage-controlled oscillator neuron model and discuss the effects of the additive and multiplicative noise. It is found that the additive noise can accelerate and counterwork the firing of neuron, which depends on the value of central frequency of neuron itself, while multiplicative noise can induce the continuous change or mutation of membrane potential
Experimental noise-resistant Bell-inequality violations for polarization-entangled photons
International Nuclear Information System (INIS)
Bovino, Fabio A.; Castagnoli, Giuseppe; Cabello, Adan; Lamas-Linares, Antia
2006-01-01
We experimentally demonstrate that violations of Bell's inequalities for two-photon polarization-entangled states with colored noise are extremely robust, whereas this is not the case for states with white noise. Controlling the amount of noise by using the timing compensation scheme introduced by Kim et al. [Phys. Rev. A 67, 010301(R) (2003)], we have observed violations even for states with very high noise, in excellent agrement with the predictions of Cabello et al. [Phys. Rev. A 72, 052112 (2005)
Elgaroy, E O
2013-01-01
Solar Noise Storms examines the properties and features of solar noise storm phenomenon. The book also presents some theories that can be used to gain a better understanding of the phenomenon. The coverage of the text includes topics that cover the features and behavior of noise storms, such as the observable features of noise storms; the relationship between noise storms and the observable features on the sun; and ordered behavior of storm bursts in the time-frequency plane. The book also covers the spectrum, polarization, and directivity of noise storms. The text will be of great use to astr
Noise-induced chaos in a quadratically nonlinear oscillator
International Nuclear Information System (INIS)
Gan Chunbiao
2006-01-01
The present paper focuses on the noise-induced chaos in a quadratically nonlinear oscillator. Simple zero points of the stochastic Melnikov integral theoretically mean the necessary rising of noise-induced chaotic response in the system based on the stochastic Melnikov method. To quantify the noise-induced chaos, the boundary of the system's safe basin is firstly studied and it is shown to be incursively fractal when chaos arises. Three cases are considered in simulating the safe basin of the system, i.e., the system is excited only by the harmonic excitation, by both the harmonic and the Gaussian white noise excitations, and only by the Gaussian white noise excitation. Secondly, the leading Lyapunov exponent by Rosenstein's algorithm is shown to quantify the chaotic nature of the sample time series of the system. The results show that the boundary of the safe basin can also be fractal even if the system is excited only by the external Gaussian white noise. Most importantly, the almost-harmonic, the noise-induced chaotic and the thoroughly random responses can be found in the system
Henderson, Brenda
2016-01-01
The presentation highlights NASA's jet noise research for 2016. Jet-noise modeling efforts, jet-surface interactions results, acoustic characteristics of multi-stream jets, and N+2 Supersonic Aircraft system studies are presented.
Effect of noise in computed tomographic reconstructions on detectability
International Nuclear Information System (INIS)
Hanson, K.M.
1982-01-01
The detectability of features in an image is ultimately limited by the random fluctuations in density or noise present in that image. The noise in CT reconstructions arising from the statistical fluctuations in the one-dimensional input projection measurements has an unusual character owing to the reconstruction procedure. Such CT image noise differs from the white noise normally found in images in its lack of low-frequency components. The noise power spectrum of CT reconstructions can be related to the effective density of x-ray quanta detected in the projection measurements, designated as NEQ (noise-equivalent quanta). The detectability of objects that are somewhat larger than the spatial resolution is directly related to NEQ. Since contrast resolution may be defined in terms of the ability to detect large, low-contrast objects, the measurement of a CT scanner's NEQ may be used to characterize its contrast sensitivity
Stark shift of impurity doped quantum dots: Role of noise
Arif, Sk. Md.; Bera, Aindrila; Ghosh, Anuja; Ghosh, Manas
2018-02-01
Present study makes a punctilious investigation of the profiles of Stark shift (SS) of doped GaAs quantum dot (QD) under the supervision of Gaussian white noise. A few physical parameters have been varied and the consequent variations in the SS profiles have been monitored. The said physical parameters comprise of magnetic field, confinement potential, dopant location, dopant potential, noise strength, aluminium concentration (only for AlxGa1-x As alloy QD), position-dependent effective mass (PDEM), position-dependent dielectric screening function (PDDSF), anisotropy, hydrostatic pressure (HP) and temperature. The SS profiles unfurl interesting features that heavily depend upon the particular physical quantity concerned, presence/absence of noise and the manner (additive/multiplicative) noise enters the system. The study highlights feasible means of maximizing SS of doped QD in presence of noise by suitable adjustment of several control parameters. The study deems importance in view of technological applications of QD devices where noise plays some prominent role.
Hallas, Tony
There are two distinct kinds of noise - structural and color. Each requires a specific method of attack to minimize. The great challenge is to reduce the noise without reducing the faint and delicate detail in the image. My most-used and favorite noise suppression is found in Photoshop CS 5 Camera Raw. If I cannot get the desired results with the first choice, I will use Noise Ninja, which has certain advantages in some situations that we will cover.
DeForest, Craig; Seaton, Daniel B.; Darnell, John A.
2017-08-01
I present and demonstrate a new, general purpose post-processing technique, "3D noise gating", that can reduce image noise by an order of magnitude or more without effective loss of spatial or temporal resolution in typical solar applications.Nearly all scientific images are, ultimately, limited by noise. Noise can be direct Poisson "shot noise" from photon counting effects, or introduced by other means such as detector read noise. Noise is typically represented as a random variable (perhaps with location- or image-dependent characteristics) that is sampled once per pixel or once per resolution element of an image sequence. Noise limits many aspects of image analysis, including photometry, spatiotemporal resolution, feature identification, morphology extraction, and background modeling and separation.Identifying and separating noise from image signal is difficult. The common practice of blurring in space and/or time works because most image "signal" is concentrated in the low Fourier components of an image, while noise is evenly distributed. Blurring in space and/or time attenuates the high spatial and temporal frequencies, reducing noise at the expense of also attenuating image detail. Noise-gating exploits the same property -- "coherence" -- that we use to identify features in images, to separate image features from noise.Processing image sequences through 3-D noise gating results in spectacular (more than 10x) improvements in signal-to-noise ratio, while not blurring bright, resolved features in either space or time. This improves most types of image analysis, including feature identification, time sequence extraction, absolute and relative photometry (including differential emission measure analysis), feature tracking, computer vision, correlation tracking, background modeling, cross-scale analysis, visual display/presentation, and image compression.I will introduce noise gating, describe the method, and show examples from several instruments (including SDO
Engineering, Colorado School of Mines, 2011 B.S., Chemical Engineering, University of Colorado at Boulder Research Assistant, Colorado School of Mines, Department of Chemical Engineering, 2006-2011 Field Team Erick A. White Photo of Erick A. White Erick White Chemical Reaction Engineer Erick.White@nrel.gov
Effects of noise in excitable systems
International Nuclear Information System (INIS)
Lindner, B.; Garcia-Ojalvo, J.; Neiman, A.; Schimansky-Geier, L.
2004-01-01
We review the behavior of theoretical models of excitable systems driven by Gaussian white noise. We focus mainly on those general properties of such systems that are due to noise, and present several applications of our findings in biophysics and lasers. As prototypes of excitable stochastic dynamics we consider the FitzHugh-Nagumo and the leaky integrate-and-fire model, as well as cellular automata and phase models. In these systems, taken as individual units or as networks of globally or locally coupled elements, we study various phenomena due to noise, such as noise-induced oscillations, stochastic resonance, stochastic synchronization, noise-induced phase transitions and noise-induced pulse and spiral dynamics. Our approach is based on stochastic differential equations and their corresponding Fokker-Planck equations, treated by both analytical calculations and/or numerical simulations. We calculate and/or measure the rate and diffusion coefficient of the excitation process, as well as spectral quantities like power spectra and degree of coherence. Combined with a multiparametric bifurcation analysis of the corresponding cumulant equations, these approaches provide a comprehensive picture of the multifaceted dynamical behaviour of noisy excitable systems
Aircrafts' taxi noise emission
Asensio, C.; Pagan Munoz, Raul; López, J.M.
2008-01-01
An investigation has been conducted, with the objective of creating a database of inputs that can be used with noise prediction software, to evaluate noise of aircraft taxing movements and community noise exposure levels. The acoustic consultant can use these data with any of the software packages,
Highly noise resistant multiqubit quantum correlations
Laskowski, Wiesław; Vértesi, Tamás; Wieśniak, Marcin
2015-11-01
We analyze robustness of correlations of the N-qubit GHZ and Dicke states against white noise admixture. For sufficiently large N, the Dicke states (for any number of excitations) lead to more robust violation of local realism than the GHZ states (e.g. for N > 8 for the W state). We also identify states that are the most resistant to white noise. Surprisingly, it turns out that these states are the GHZ states augmented with fully product states. Based on our numerical analysis conducted up to N = 8, and an analytical formula derived for any N parties, we conjecture that the three-qubit GHZ state augmented with a product of (N - 3) pure qubits is the most robust against white noise admixture among any N-qubit state. As a by-product, we derive a single Bell inequality and show that it is violated by all pure entangled states of a given number of parties. This gives an alternative proof of Gisin’s theorem.
Highly noise resistant multiqubit quantum correlations
International Nuclear Information System (INIS)
Laskowski, Wiesław; Wieśniak, Marcin; Vértesi, Tamás
2015-01-01
We analyze robustness of correlations of the N-qubit GHZ and Dicke states against white noise admixture. For sufficiently large N, the Dicke states (for any number of excitations) lead to more robust violation of local realism than the GHZ states (e.g. for N > 8 for the W state). We also identify states that are the most resistant to white noise. Surprisingly, it turns out that these states are the GHZ states augmented with fully product states. Based on our numerical analysis conducted up to N = 8, and an analytical formula derived for any N parties, we conjecture that the three-qubit GHZ state augmented with a product of (N − 3) pure qubits is the most robust against white noise admixture among any N-qubit state. As a by-product, we derive a single Bell inequality and show that it is violated by all pure entangled states of a given number of parties. This gives an alternative proof of Gisin’s theorem. (paper)
Taitelbaum-Swead, Riki; Fostick, Leah
2016-01-01
Everyday life includes fluctuating noise levels, resulting in continuously changing speech intelligibility. The study aims were: (1) to quantify the amount of decrease in age-related speech perception, as a result of increasing noise level, and (2) to test the effect of age on context usage at the word level (smaller amount of contextual cues). A total of 24 young adults (age 20-30 years) and 20 older adults (age 60-75 years) were tested. Meaningful and nonsense one-syllable consonant-vowel-consonant words were presented with the background noise types of speech noise (SpN), babble noise (BN), and white noise (WN), with a signal-to-noise ratio (SNR) of 0 and -5 dB. Older adults had lower accuracy in SNR = 0, with WN being the most difficult condition for all participants. Measuring the change in speech perception when SNR decreased showed a reduction of 18.6-61.5% in intelligibility, with age effect only for BN. Both young and older adults used less phonemic context with WN, as compared to other conditions. Older adults are more affected by an increasing noise level of fluctuating informational noise as compared to steady-state noise. They also use less contextual cues when perceiving monosyllabic words. Further studies should take into consideration that when presenting the stimulus differently (change in noise level, less contextual cues), other perceptual and cognitive processes are involved. © 2016 S. Karger AG, Basel.
Hybrid colored noise process with space-dependent switching rates
Bressloff, Paul C.; Lawley, Sean D.
2017-07-01
A fundamental issue in the theory of continuous stochastic process is the interpretation of multiplicative white noise, which is often referred to as the Itô-Stratonovich dilemma. From a physical perspective, this reflects the need to introduce additional constraints in order to specify the nature of the noise, whereas from a mathematical perspective it reflects an ambiguity in the formulation of stochastic differential equations (SDEs). Recently, we have identified a mechanism for obtaining an Itô SDE based on a form of temporal disorder. Motivated by switching processes in molecular biology, we considered a Brownian particle that randomly switches between two distinct conformational states with different diffusivities. In each state, the particle undergoes normal diffusion (additive noise) so there is no ambiguity in the interpretation of the noise. However, if the switching rates depend on position, then in the fast switching limit one obtains Brownian motion with a space-dependent diffusivity of the Itô form. In this paper, we extend our theory to include colored additive noise. We show that the nature of the effective multiplicative noise process obtained by taking both the white-noise limit (κ →0 ) and fast switching limit (ɛ →0 ) depends on the order the two limits are taken. If the white-noise limit is taken first, then we obtain Itô, and if the fast switching limit is taken first, then we obtain Stratonovich. Moreover, the form of the effective diffusion coefficient differs in the two cases. The latter result holds even in the case of space-independent transition rates, where one obtains additive noise processes with different diffusion coefficients. Finally, we show that yet another form of multiplicative noise is obtained in the simultaneous limit ɛ ,κ →0 with ɛ /κ2 fixed.
Noise Reduction of Measurement Data using Linear Digital Filters
Directory of Open Access Journals (Sweden)
Hitzmann B.
2007-12-01
Full Text Available In this paper Butterworth, Chebyshev (Type I and II and Elliptic digital filters are designed for signal noise reduction. On-line data measurements of substrate concentration from E. coli fed-batch cultivation process are used. Application of the designed filters leads to a successful noise reduction of on-line glucose measurements. The digital filters presented here are simple, easy to implement and effective - the used filters allow for a smart compromise between signal information and noise corruption.
Impact of image noise on gamma index calculation
International Nuclear Information System (INIS)
Chen, M; Mo, X; Parnell, D; Olivera, G; Galmarini, D; Lu, W
2014-01-01
Purpose: The Gamma Index defines an asymmetric metric between the evaluated image and the reference image. It provides a quantitative comparison that can be used to indicate sample-wised pass/fail on the agreement of the two images. The Gamma passing/failing rate has become an important clinical evaluation tool. However, the presence of noise in the evaluated and/or reference images may change the Gamma Index, hence the passing/failing rate, and further, clinical decisions. In this work, we systematically studied the impact of the image noise on the Gamma Index calculation. Methods: We used both analytic formulation and numerical calculations in our study. The numerical calculations included simulations and clinical images. Three different noise scenarios were studied in simulations: noise in reference images only, in evaluated images only, and in both. Both white and spatially correlated noises of various magnitudes were simulated. For clinical images of various noise levels, the Gamma Index of measurement against calculation, calculation against measurement, and measurement against measurement, were evaluated. Results: Numerical calculations for both the simulation and clinical data agreed with the analytic formulations, and the clinical data agreed with the simulations. For the Gamma Index of measurement against calculation, its distribution has an increased mean and an increased standard deviation as the noise increases. On the contrary, for the Gamma index of calculation against measurement, its distribution has a decreased mean and stabilized standard deviation as the noise increases. White noise has greater impact on the Gamma Index than spatially correlated noise. Conclusions: The noise has significant impact on the Gamma Index calculation and the impact is asymmetric. The Gamma Index should be reported along with the noise levels in both reference and evaluated images. Reporting of the Gamma Index with switched roles of the images as reference and
Impact of Image Noise on Gamma Index Calculation
Chen, M.; Mo, X.; Parnell, D.; Olivera, G.; Galmarini, D.; Lu, W.
2014-03-01
Purpose: The Gamma Index defines an asymmetric metric between the evaluated image and the reference image. It provides a quantitative comparison that can be used to indicate sample-wised pass/fail on the agreement of the two images. The Gamma passing/failing rate has become an important clinical evaluation tool. However, the presence of noise in the evaluated and/or reference images may change the Gamma Index, hence the passing/failing rate, and further, clinical decisions. In this work, we systematically studied the impact of the image noise on the Gamma Index calculation. Methods: We used both analytic formulation and numerical calculations in our study. The numerical calculations included simulations and clinical images. Three different noise scenarios were studied in simulations: noise in reference images only, in evaluated images only, and in both. Both white and spatially correlated noises of various magnitudes were simulated. For clinical images of various noise levels, the Gamma Index of measurement against calculation, calculation against measurement, and measurement against measurement, were evaluated. Results: Numerical calculations for both the simulation and clinical data agreed with the analytic formulations, and the clinical data agreed with the simulations. For the Gamma Index of measurement against calculation, its distribution has an increased mean and an increased standard deviation as the noise increases. On the contrary, for the Gamma index of calculation against measurement, its distribution has a decreased mean and stabilized standard deviation as the noise increases. White noise has greater impact on the Gamma Index than spatially correlated noise. Conclusions: The noise has significant impact on the Gamma Index calculation and the impact is asymmetric. The Gamma Index should be reported along with the noise levels in both reference and evaluated images. Reporting of the Gamma Index with switched roles of the images as reference and
Classical noise, quantum noise and secure communication
International Nuclear Information System (INIS)
Tannous, C; Langlois, J
2016-01-01
Secure communication based on message encryption might be performed by combining the message with controlled noise (called pseudo-noise) as performed in spread-spectrum communication used presently in Wi-Fi and smartphone telecommunication systems. Quantum communication based on entanglement is another route for securing communications as demonstrated by several important experiments described in this work. The central role played by the photon in unifying the description of classical and quantum noise as major ingredients of secure communication systems is highlighted and described on the basis of the classical and quantum fluctuation dissipation theorems. (review)
Slow cortical evoked potentials after noise exposure
Energy Technology Data Exchange (ETDEWEB)
von Wedel, H; Opitz, H J
1979-07-01
Human cortical evoked potentials under conditions of stimuation are registrated in the post-stimulatory phase of a five minutes lasting equally masking white noise (90 dB HL). Changes of the evoked potentials during adaptation, possible analogy with high tone losses after noise representation and the origin of tinnitus are examined. Stimulation was started 3 sec after the off-effect of the noise. For five minutes periodically tone bursts were represented. Each train of stimulation consists of tone bursts of three frequencies: 2 kcs, 4 kcs, 8 kcs. The 0.5 sec lasting tones were separated by pauses of 2 sec. During the experiment stimulation and analysis were controlled by a computer. Changes in latency and amplitudes of the cortical evoked potentials were registered. Changes of the adaptation patterns as a function of the poststimulatory time are discussed.
Laser line shape and spectral density of frequency noise
International Nuclear Information System (INIS)
Stephan, G.M.; Blin, S.; Besnard, P.; Tam, T.T.; Tetu, M.
2005-01-01
Published experimental results show that single-mode laser light is characterized in the microwave range by a frequency noise which essentially includes a white part and a 1/f (flicker) part. We theoretically show that the spectral density (the line shape) which is compatible with these results is a Voigt profile whose Lorentzian part or homogeneous component is linked to the white noise and the Gaussian part to the 1/f noise. We measure semiconductor laser line profiles and verify that they can be fit with Voigt functions. It is also verified that the width of the Lorentzian part varies like 1/P where P is the laser power while the width of the Gaussian part is more of a constant. Finally, we theoretically show from first principles that laser line shapes are also described by Voigt functions where the Lorentzian part is the laser Airy function and the Gaussian part originates from population noise
Analysis and removing noise from speech using wavelet transform
Tomala, Karel; Voznak, Miroslav; Partila, Pavol; Rezac, Filip; Safarik, Jakub
2013-05-01
The paper discusses the use of Discrete Wavelet Transform (DWT) and Stationary Wavelet Transform (SWT) wavelet in removing noise from voice samples and evaluation of its impact on speech quality. One significant part of Quality of Service (QoS) in communication technology is the speech quality assessment. However, this part is seriously overlooked as telecommunication providers often focus on increasing network capacity, expansion of services offered and their enforcement in the market. Among the fundamental factors affecting the transmission properties of the communication chain is noise, either at the transmitter or the receiver side. A wavelet transform (WT) is a modern tool for signal processing. One of the most significant areas in which wavelet transforms are used is applications designed to suppress noise in signals. To remove noise from the voice sample in our experiment, we used the reference segment of the voice which was distorted by Gaussian white noise. An evaluation of the impact on speech quality was carried out by an intrusive objective algorithm Perceptual Evaluation of Speech Quality (PESQ). DWT and SWT transformation was applied to voice samples that were devalued by Gaussian white noise. Afterwards, we determined the effectiveness of DWT and SWT by means of objective algorithm PESQ. The decisive criterion for determining the quality of a voice sample once the noise had been removed was Mean Opinion Score (MOS) which we obtained in PESQ. The contribution of this work lies in the evaluation of efficiency of wavelet transformation to suppress noise in voice samples.
Sgarbozza, M.; Depitre, A.
1992-04-01
A discussion of the characteristics and the noise levels of combat aircraft and of a transport aircraft in taking off and landing are presented. Some methods of noise reduction are discussed, including the following: operational anti-noise procedures; and concepts of future engines (silent post-combustion and variable cycle). Some measurement results concerning the noise generated in flight at great speeds and low altitude will also be examined. Finally, the protection of the environment of French air bases against noise will be described and the possibilities of regulation examined.
Direct-reading dial for noise temperature and noise resistance
DEFF Research Database (Denmark)
Diamond, J.M.
1967-01-01
An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance.......An attenuator arrangement for a noise generator is described. The scheme permits direct reading of both noise resistance and noise temperature¿the latter with a choice of source resistance....
Noise Budget and Interstellar Medium Mitigation Advances in the NANOGrav Pulsar Timing Array
Dolch, T.; NANOGrav Collaboration; Chatterjee, S.; Cordes, J. M.; Demorest, P. B.; Ellis, J. A.; Jones, M. L.; Lam, M. T.; Lazio, T. J. W.; Levin, L.; McLaughlin, M. A.; Palliyaguru, N. T.; Stinebring, D. R.
2018-02-01
Gravitational wave (GW) detection with pulsar timing arrays (PTAs) requires accurate noise characterization. The noise of our Galactic-scale GW detector has been systematically evaluated by the Noise Budget and Interstellar Medium Mitigation working groups within the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration. Intrinsically, individual radio millisecond pulsars (MSPs) used by NANOGrav can have some degree of achromatic red spin noise, as well as white noise due to pulse phase jitter. Along any given line-of-sight, the ionized interstellar medium contributes chromatic noise through dispersion measure (DM) variations, interstellar scintillation, and scattering. These effects contain both red and white components. In the future, with wideband receivers, the effects of frequency-dependent DM will become important. Having anticipated and measured these diverse sources of detector noise, the NANOGrav PTA remains well-poised to detect low-frequency GWs.
International Nuclear Information System (INIS)
Ahmed, A.; Barfeh, M.A.G.
2001-01-01
In air-conditioning system the noise generated by supply fan is carried by conditioned air through the ductwork. The noise created in ductwork run may be transmission, regenerative and ductborne. Transmission noise is fan noise, regenerative noise is due to turbulence in flow and ductborne noise is the noise radiating from duct to surroundings. Some noise is attenuated in ducts also but if noise level is high then it needs to be attenuated. A simple mitre bend can attenuate-noise. This principle is extended to V and M-shape ducts with inside lining of fibreglass, which gave maximum attenuation of 77 dB and 62 dB respectively corresponding to 8 kHz frequency as compared to mitre, bend giving maximum 18 dB attenuation. Sound level meter measured sound levels with octave band filter and tests were conducted in anechoic room. A V-shape attenuator can be used at fan outlet and high frequency noise can be minimized greatly. (author)
Eliminating thermal violin spikes from LIGO noise
Energy Technology Data Exchange (ETDEWEB)
Santamore, D. H.; Levin, Yuri
2001-08-15
We have developed a scheme for reducing LIGO suspension thermal noise close to violin-mode resonances. The idea is to monitor directly the thermally induced motion of a small portion of (a 'point' on) each suspension fiber, thereby recording the random forces driving the test-mass motion close to each violin-mode frequency. One can then suppress the thermal noise by optimally subtracting the recorded fiber motions from the measured motion of the test mass, i.e., from the LIGO output. The proposed method is a modification of an analogous but more technically difficult scheme by Braginsky, Levin and Vyatchanin for reducing broad-band suspension thermal noise. The efficiency of our method is limited by the sensitivity of the sensor used to monitor the fiber motion. If the sensor has no intrinsic noise (i.e. has unlimited sensitivity), then our method allows, in principle, a complete removal of violin spikes from the thermal-noise spectrum. We find that in LIGO-II interferometers, in order to suppress violin spikes below the shot-noise level, the intrinsic noise of the sensor must be less than {approx}2 x 10{sup -13} cm/Hz. This sensitivity is two orders of magnitude greater than that of currently available sensors.
Eliminating thermal violin spikes from LIGO noise
International Nuclear Information System (INIS)
Santamore, D. H.; Levin, Yuri
2001-01-01
We have developed a scheme for reducing LIGO suspension thermal noise close to violin-mode resonances. The idea is to monitor directly the thermally induced motion of a small portion of (a 'point' on) each suspension fiber, thereby recording the random forces driving the test-mass motion close to each violin-mode frequency. One can then suppress the thermal noise by optimally subtracting the recorded fiber motions from the measured motion of the test mass, i.e., from the LIGO output. The proposed method is a modification of an analogous but more technically difficult scheme by Braginsky, Levin and Vyatchanin for reducing broad-band suspension thermal noise. The efficiency of our method is limited by the sensitivity of the sensor used to monitor the fiber motion. If the sensor has no intrinsic noise (i.e. has unlimited sensitivity), then our method allows, in principle, a complete removal of violin spikes from the thermal-noise spectrum. We find that in LIGO-II interferometers, in order to suppress violin spikes below the shot-noise level, the intrinsic noise of the sensor must be less than ∼2 x 10 -13 cm/Hz. This sensitivity is two orders of magnitude greater than that of currently available sensors
International Nuclear Information System (INIS)
Holzfuss, J.
1996-01-01
Noise reduction is a problem being encountered in a variety of applications, such as environmental noise cancellation, signal recovery and separation. Passive noise reduction is done with the help of absorbers. Active noise reduction includes the transmission of phase inverted signals for the cancellation. This paper is about a threefold active approach to noise reduction. It includes the separation of a combined source, which consists of both a noise and a signal part. With the help of interaction with the source by scanning it and recording its response, modeling as a nonlinear dynamical system is achieved. The analysis includes phase space analysis and global radial basis functions as tools for the prediction used in a subsequent cancellation procedure. Examples are given which include noise reduction of speech. copyright 1996 American Institute of Physics
Energy Technology Data Exchange (ETDEWEB)
Fegeant, Olivier [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Building Sciences
2002-02-01
A rapid growth of installed wind power capacity is expected in the next few years. However, the siting of wind turbines on a large scale raises concerns about their environmental impact, notably with respect to noise. To this end, variable speed wind turbines offer a promising solution for applications in densely populated areas like the European countries, as this design would enable an efficient utilisation of the masking effect due to ambient noise. In rural and recreational areas where wind turbines are sited, the ambient noise originates from the action of wind on the vegetation and about the listener's ear (pseudo-noise). It shows a wind speed dependence similar to that of the noise from a variable speed wind turbine and can therefore mask the latter for a wide range of conditions. However, a problem inherent to the design of these machines is their proclivity to pure tone generation, because of the enhanced difficulty of avoiding structural resonances in the mechanical parts. Pure tones are deemed highly annoying and are severely regulated by most noise policies. In relation to this problem, the vibration transmission of structure-borne sound to the tower of the turbine is investigated, in particular when the tower is stiffened at its upper end. Furthermore, since noise annoyance due to wind turbine is mostly a masking issue, the wind-related sources of ambient noise are studied and their masking potentials assessed. With this aim, prediction models for wind-induced vegetation noise and pseudo-noise have been developed. Finally, closely related to the effect of masking, is the difficulty, regularly encountered by local authorities and wind farm developers, to measure noise immission from wind turbines. A new measurement technique has thus been developed in the course of this work. Through improving the signal-to-noise ratio between wind turbine noise and ambient noise, the new technique yields more accurate measurement results.
Attention-related modulation of auditory brainstem responses during contralateral noise exposure.
Ikeda, Kazunari; Sekiguchi, Takahiro; Hayashi, Akiko
2008-10-29
As determinants facilitating attention-related modulation of the auditory brainstem response (ABR), two experimental factors were examined: (i) auditory discrimination; and (ii) contralateral masking intensity. Tone pips at 80 dB sound pressure level were presented to the left ear via either single-tone exposures or oddball exposures, whereas white noise was delivered continuously to the right ear at variable intensities (none--80 dB sound pressure level). Participants each conducted two tasks during stimulation, either reading a book (ignoring task) or detecting target tones (attentive task). Task-related modulation within the ABR range was found only during oddball exposures at contralateral masking intensities greater than or equal to 60 dB. Attention-related modulation of ABR can thus be detected reliably during auditory discrimination under contralateral masking of sufficient intensity.
Silvestre, Daphné; Cavanagh, Patrick; Arleo, Angelo; Allard, Rémy
2017-02-01
External noise paradigms are widely used to characterize sensitivity by comparing the effect of a variable on contrast threshold when it is limited by internal versus external noise. A basic assumption of external noise paradigms is that the processing properties are the same in low and high noise. However, recent studies (e.g., Allard & Cavanagh, 2011; Allard & Faubert, 2014b) suggest that this assumption could be violated when using spatiotemporally localized noise (i.e., appearing simultaneously and at the same location as the target) but not when using spatiotemporally extended noise (i.e., continuously displayed, full-screen, dynamic noise). These previous findings may have been specific to the crowding and 0D noise paradigms that were used, so the purpose of the current study is to test if this violation of noise-invariant processing also occurs in a standard contrast detection task in white noise. The rationale of the current study is that local external noise triggers the use of recognition rather than detection and that a recognition process should be more affected by uncertainty about the shape of the target than one involving detection. To investigate the contribution of target knowledge on contrast detection, the effect of orientation uncertainty was evaluated for a contrast detection task in the absence of noise and in the presence of spatiotemporally localized or extended noise. A larger orientation uncertainty effect was observed with temporally localized noise than with temporally extended noise or with no external noise, indicating a change in the nature of the processing for temporally localized noise. We conclude that the use of temporally localized noise in external noise paradigms risks triggering a shift in process, invalidating the noise-invariant processing required for the paradigm. If, instead, temporally extended external noise is used to match the properties of internal noise, no such processing change occurs.
Judgments of aircraft noise in a traffic noise background
Powell, C. A.; Rice, C. G.
1975-01-01
An investigation was conducted to determine subjective response to aircraft noise in different road traffic backgrounds. In addition, two laboratory techniques for presenting the aircraft noise with the background noise were evaluated. For one technique, the background noise was continuous over an entire test session; for the other, the background noise level was changed with each aircraft noise during a session. Subjective response to aircraft noise was found to decrease with increasing background noise level, for a range of typical indoor noise levels. Subjective response was found to be highly correlated with the Noise Pollution Level (NPL) measurement scale.
Beamspace Adaptive Beamforming for Hydrodynamic Towed Array Self-Noise Cancellation
National Research Council Canada - National Science Library
Premus, Vincent
2001-01-01
... against signal self-nulling associated with steering vector mismatch. Particular attention is paid to the definition of white noise gain as the metric that reflects the level of mainlobe adaptive nulling for an adaptive beamformer...
Beamspace Adaptive Beamforming for Hydrodynamic Towed Array Self-Noise Cancellation
National Research Council Canada - National Science Library
Premus, Vincent
2000-01-01
... against signal self-nulling associated with steering vector mismatch. Particular attention is paid to the definition of white noise gain as the metric that reflects the level of mainlobe adaptive nulling for an adaptive beamformer...
Phase noise in RF and microwave amplifiers.
Boudot, Rodolphe; Rubiola, Enrico
2012-12-01
Understanding amplifier phase noise is a critical issue in many fields of engineering and physics, such as oscillators, frequency synthesis, telecommunication, radar, and spectroscopy; in the emerging domain of microwave photonics; and in exotic fields, such as radio astronomy, particle accelerators, etc. Focusing on the two main types of base noise in amplifiers, white and flicker, the power spectral density of the random phase φ(t) is Sφ(f) = b(0) + b(-1)/f. White phase noise results from adding white noise to the RF spectrum in the carrier region. For a given RF noise level, b(0) is proportional to the reciprocal of the carrier power P(0). By contrast, flicker results from a near-dc 1/f noise-present in all electronic devices-which modulates the carrier through some parametric effect in the semiconductor. Thus, b(-1) is a parameter of the amplifier, constant in a wide range of P(0). The consequences are the following: Connecting m equal amplifiers in parallel, b(-1) is 1/m times that of one device. Cascading m equal amplifiers, b(-1) is m times that of one amplifier. Recirculating the signal in an amplifier so that the gain increases by a power of m (a factor of m in decibels) as a result of positive feedback (regeneration), we find that b(-1) is m(2) times that of the amplifier alone. The feedforward amplifier exhibits extremely low b(-1) because the carrier is ideally nulled at the input of its internal error amplifier. Starting with an extensive review of the literature, this article introduces a system-oriented model which describes the phase flickering. Several amplifier architectures (cascaded, parallel, etc.) are analyzed systematically, deriving the phase noise from the general model. There follow numerous measurements of amplifiers using different technologies, including some old samples, and in a wide frequency range (HF to microwaves), which validate the theory. In turn, theory and results provide design guidelines and give suggestions for CAD and
Stochastic partial differential equations a modeling, white noise functional approach
Holden, Helge; Ubøe, Jan; Zhang, Tusheng
1996-01-01
This book is based on research that, to a large extent, started around 1990, when a research project on fluid flow in stochastic reservoirs was initiated by a group including some of us with the support of VISTA, a research coopera tion between the Norwegian Academy of Science and Letters and Den norske stats oljeselskap A.S. (Statoil). The purpose of the project was to use stochastic partial differential equations (SPDEs) to describe the flow of fluid in a medium where some of the parameters, e.g., the permeability, were stochastic or "noisy". We soon realized that the theory of SPDEs at the time was insufficient to handle such equations. Therefore it became our aim to develop a new mathematically rigorous theory that satisfied the following conditions. 1) The theory should be physically meaningful and realistic, and the corre sponding solutions should make sense physically and should be useful in applications. 2) The theory should be general enough to handle many of the interesting SPDEs that occur in r...
Experimental Study of SBS Suppression via White Noise Phase Modulation
2014-02-10
fiber optical parametric amplifiers,” Opt. Communications 283, 2607-2610 (2010). [8] Coles, J. B., Kuo, B. P.-P., Alie , N., Moro, S., Bres, C.-S...V., Farley, K., Leveille, R., Galipeau, J., Majid , I., Christensen, S., Samson, B., Tankala, K. “kW level narrow linewidth Yb fiber amplifiers for
Oracle posterior rates in the White Noise Model
Babenko, A.
2010-01-01
All the results about posterior rates obtained until now are related to the optimal (minimax) rates for the estimation problem over the corresponding nonparametric smoothness classes, i.e. of a global nature. In the meantime, a new local approach to optimality has been developed within the
assessment of noise pollutio noise pollutio noise pollution
African Journals Online (AJOL)
eobe
re above the recommended limit of 85 dB(A) and these high noise intensit related health ... multiple workplaces i.e. steel pipe and a unit factory ... construction material. However .... selected workers, particularly the machine operators. In some ...
Does ambient noise or hypobaric atmosphere influence olfactory and gustatory function?
Rahne, Torsten; Köppke, Robert; Nehring, Michael; Plontke, Stefan K; Fischer, Hans-Georg
2018-01-01
Multidimensional food perception is based mainly on gustatory and olfactory function. Recent research has demonstrated that hypobaric pressure impairs gustatory function and that background noise or distracting auditory stimulation impairs olfactory function. Using a hypobaric chamber, the odor identification, discrimination, and thresholds as well as taste identification and threshold scores were measured in 16 healthy male volunteers under normal and hypobaric (6380 ft) conditions using clinically validated tests. In both conditions, background noise was either canceled out or replaced by white noise presentation (70 dB sound pressure level). Olfactory sensitivity for n-butanol and gustatory sensitivity were impaired in a hypobaric atmosphere. White noise did not influence the odor test results. White noise stimulation impaired sensitivity for sour and sweet but not for bitter or salty tastants. We conclude that hypobaric or noisy environments could impair gustatory and olfactory sensitivity selectively for particular tastants and odorants.
1982-01-01
A demonstration conducted last winter at the Tip Top Poultry Plant intended to show poultry plant managers from all over the U.S. potential solutions to the problem of plant noise. Plastic covers used over sound absorbing materials need to meet cleanability requirements, high- pressure water cleaning and other harsh maintenance procedures peculiar to the poultry processing industry. For the demonstration, Fiber Flex, Inc. manufactured and donated 750 noise panels; Owens-Corning Fiberglas Corporation donated the fiberglas cores; and the cover material was purchased from Howe and Bainbridge. The Engineering Experiment Station (EES) conducted before and after noise surveys and is evaluating the effect of noise reduction on turnover and productivity in the demonstration plant. EES plans to conduct a noise abatement workshop and update a handbook to help poultry processors with noise problems. EES study and demonstration may be applicable to other food processing plants where similar sanitary constraints exist.
International Nuclear Information System (INIS)
Akram, N.
1999-01-01
In this report we describe the concept of adaptive noise canceling, an alternative method of estimating signals corrupted by additive noise of interference. The method uses 'primary' input containing the corrupted signal and a 'reference' input containing noise correlated in some unknown way with the primary noise, the reference input is adaptively filtered and subtracted from the primary input to obtain the signal estimate. Adaptive filtering before subtraction allows the treatment of inputs that are deterministic or stochastic, stationary or time variable. When the reference input is free of signal and certain other conditions are met then noise in the primary input can be essentially eliminated without signal distortion. It is further shown that the adaptive filter also acts as notch filter. Simulated results illustrate the usefulness of the adaptive noise canceling technique. (author)
DEFF Research Database (Denmark)
Olsen, Steen Østergaard; Nielsen, Lars Holme; Lantz, Johannes
2012-01-01
The acceptable noise level (ANL) is used to quantify the amount of background noise that subjects can accept while listening to speech, and is suggested for prediction of individual hearing-aid use. The aim of this study was to assess the repeatability of the ANL measured in normal-hearing subjects...... using running Danish and non-semantic speech materials as stimuli and modulated speech-spectrum and multi-talker babble noises as competing stimuli....
DEFF Research Database (Denmark)
Prior, Andrew
2011-01-01
The notion of noise occupies a contested territory, in which it is framed as pollution and detritus even as it makes its opposite a possibility - noise is always defined in opposition to something else, even if this ‘other’ is not quite clear. This paper explores noise in the context of ‘the...... interface’ asking what its affordances as an idea may contribute to our understanding of interface. I draw historically on information theory in particular to initiate this exploration....
DEFF Research Database (Denmark)
Olsen, Steen Østergaard; Nielsen, Lars Holme; Lantz, Johannes
2012-01-01
The acceptable noise level (ANL) is used to quantify the amount of background noise that subjects can accept while listening to speech, and is suggested for prediction of individual hearing-aid use. The aim of this study was to assess the repeatability of the ANL measured in normal-hearing subjec...... using running Danish and non-semantic speech materials as stimuli and modulated speech-spectrum and multi-talker babble noises as competing stimuli....
Logical stochastic resonance in triple-well potential systems driven by colored noise.
Zhang, Huiqing; Xu, Yong; Xu, Wei; Li, Xiuchun
2012-12-01
In this work, the logic stochastic resonance (LSR) phenomenon in a class of stochastic triple-well potential systems is investigated. Approximate Fokker-Planck equation is first obtained by using decoupling approximation. Then, we show that LSR can be successfully induced by additive or multiplicative Gaussian colored noise in some cases. In the absence of internal noise, LSR implementation seems impossible for a = 0 (The parameter a characterizes the depth of the potential well) since the two side wells are so deep that the particle cannot hop over the barrier into the middle well when the input signal is 0. With the increasing of a, the optimal noise band to yield flexible logic gates appears and moves to higher level of noise as the correlation time of noise increases. Compared with the Gaussian white noise, the reliable region in the parameter plane of potential depth parameter a and additive noise strength D first expands and then shrinks with increasing noise color. Furthermore, the effects of multiplicative Gaussian colored noise on LSR are investigated. It was found that the flexible and reliable logic behavior can be yielded for a = 0 due to the fact that the multiplicative Gaussian colored noise strongly affects the shape of the potential function. With the increasing of a, i.e., a = 0.25, multiplicative Gaussian white noise cannot yield desired logic behavior. Fortunately, LSR can also be expected by adjusting the correlation time of Gaussian colored noise. It can also be observed that the reliable region in the parameter plane of potential depth parameter a and multiplicative noise strength Q is small for the case of Gaussian white noise and it becomes larger with the increasing of noise color.
DEFF Research Database (Denmark)
Jensen, Karl Kristoffer
2005-01-01
Sinusoids are used for making harmonic and other sounds. In order to having life in the sounds and adding a wide variety of noises, irregularities are inserted in the frequency and amplitudes. A simple and intuitive noise model is presented, consisting of a low-pass filtered noise, and having...... control for strength and bandwidth. The noise is added on the frequency and amplitudes of the sinusoids, and the resulting irregularity’s (jitter and shimmer) bandwidth is derived. This, together with an overview of investigation methods of the jitter and shimmer results in an analysis of the necessary...
Karabasov, S A
2010-08-13
Jets are one of the most fascinating topics in fluid mechanics. For aeronautics, turbulent jet-noise modelling is particularly challenging, not only because of the poor understanding of high Reynolds number turbulence, but also because of the extremely low acoustic efficiency of high-speed jets. Turbulent jet-noise models starting from the classical Lighthill acoustic analogy to state-of-the art models were considered. No attempt was made to present any complete overview of jet-noise theories. Instead, the aim was to emphasize the importance of sound generation and mean-flow propagation effects, as well as their interference, for the understanding and prediction of jet noise.
Landing gear noise attenuation
Moe, Jeffrey W. (Inventor); Whitmire, Julia (Inventor); Kwan, Hwa-Wan (Inventor); Abeysinghe, Amal (Inventor)
2011-01-01
A landing gear noise attenuator mitigates noise generated by airframe deployable landing gear. The noise attenuator can have a first position when the landing gear is in its deployed or down position, and a second position when the landing gear is in its up or stowed position. The noise attenuator may be an inflatable fairing that does not compromise limited space constraints associated with landing gear retraction and stowage. A truck fairing mounted under a truck beam can have a compliant edge to allow for non-destructive impingement of a deflected fire during certain conditions.
Statistics of a neuron model driven by asymmetric colored noise.
Müller-Hansen, Finn; Droste, Felix; Lindner, Benjamin
2015-02-01
Irregular firing of neurons can be modeled as a stochastic process. Here we study the perfect integrate-and-fire neuron driven by dichotomous noise, a Markovian process that jumps between two states (i.e., possesses a non-Gaussian statistics) and exhibits nonvanishing temporal correlations (i.e., represents a colored noise). Specifically, we consider asymmetric dichotomous noise with two different transition rates. Using a first-passage-time formulation, we derive exact expressions for the probability density and the serial correlation coefficient of the interspike interval (time interval between two subsequent neural action potentials) and the power spectrum of the spike train. Furthermore, we extend the model by including additional Gaussian white noise, and we give approximations for the interspike interval (ISI) statistics in this case. Numerical simulations are used to validate the exact analytical results for pure dichotomous noise, and to test the approximations of the ISI statistics when Gaussian white noise is included. The results may help to understand how correlations and asymmetry of noise and signals in nerve cells shape neuronal firing statistics.
Astronauts McDivitt and White look over training plans
1965-01-01
Astronauts James A. McDivitt (left) and Edward H. White II are shown looking over training plans at Cape Kennedy during prelaunch preparations. The NASA Headquarters alternative photo number is 65-H-275.
Realistic Noise Assessment and Strain Analysis of Iranian Permanent GPS Stations
Razeghi, S. M.; Amiri Simkooei, A. A.; Sharifi, M. A.
2012-04-01
To assess noise characteristics of Iranian Permanent GPS Stations (IPGS), northwestern part of this network namely Azerbaijan Continuous GPS Station (ACGS), was selected. For a realistic noise assessment it is required to model all deterministic signals of the GPS time series by means of least squares harmonic estimation (LS-HE) and derive all periodic behavior of the series. After taking all deterministic signals into account, the least squares variance component estimation (LS-VCE) is used to obtain a realistic noise model (white noise plus flicker noise) of the ACGS. For this purpose, one needs simultaneous GPS time series for which a multivariate noise assessment is applied. Having determined realistic noise model, a realistic strain analysis of the network is obtained for which one relies on the finite element methods. Finite element is now considered to be a new functional model and the new stochastic model is given based on the multivariate noise assessment using LS-VCE. The deformation rates of the components along with their full covariance matries are input to the strain analysis. Further, the results are also provided using a pure white noise model. The normalized strains for these two models show that the strain parameters derived from a realistic noise model are less significant than those derived from the white model. This could be either due to the short time span of the time series used or due to the intrinsic behavior of the strain parameters in the ACGS. Longer time series are required to further elaborate this issue.
Sounds and Noises. A Position Paper on Noise Pollution.
Chapman, Thomas L.
This position paper focuses on noise pollution and the problems and solutions associated with this form of pollution. The paper is divided into the following five sections: Noise and the Ear, Noise Measurement, III Effects of Noise, Acoustics and Action, and Programs and Activities. The first section identifies noise and sound, the beginnings of…
Moment stability for a predator–prey model with parametric dichotomous noises
International Nuclear Information System (INIS)
Jin Yan-Fei
2015-01-01
In this paper, we investigate the solution moment stability for a Harrison-type predator–prey model with parametric dichotomous noises. Using the Shapiro–Loginov formula, the equations for the first-order and second-order moments are obtained and the corresponding stable conditions are given. It is found that the solution moment stability depends on the noise intensity and correlation time of noise. The first-order and second-order moments become unstable with the decrease of correlation time. That is, the dichotomous noise can improve the solution moment stability with respect to Gaussian white noise. Finally, some numerical results are presented to verify the theoretical analyses. (paper)
Kepler, S. O.; Romero, Alejandra Daniela; Pelisoli, Ingrid; Ourique, Gustavo
2017-01-01
White dwarf stars are the final stage of most stars, born single or in multiple systems. We discuss the identification, magnetic fields, and mass distribution for white dwarfs detected from spectra obtained by the Sloan Digital Sky Survey up to Data Release 13 in 2016, which lead to the increase in the number of spectroscopically identified white dwarf stars from 5000 to 39000. This number includes only white dwarf stars with log g >= 6.5 stars, i.e., excluding the Extremely Low Mass white dw...
African Journals Online (AJOL)
DR. AMINU
Department of Chemistry Bayero University, P. M. B. 3011, Kano, Nigeria. E-mail: hnuhu2000@yahoo.com. ABSTRACT. The manganese (II), cobalt (II), nickel (II) and .... water and common organic solvents, but are readily soluble in acetone. The molar conductance measurement [Table 3] of the complex compounds in.
DEFF Research Database (Denmark)
Prior, Andrew
This PhD is concerned with the use of noise as a material within media arts practice, especially in ‘post-digital’ contexts such as glitch electronica, glitch art and uses of old media. It examines the relationship between informational culture and noise, exploring the ways in which the structuring...
Post commissioning noise study
International Nuclear Information System (INIS)
Heraud, P.
2008-01-01
This presentation described a wind farm post-commissioning study conducted at a wind farm owned by Helimax Energy Inc. The farm was located in a partly-forested, partly cultivated region in Quebec that featured gently rolling hills. Over 600 dwellings were located within 2 km of the wind farm, and 44 dwellings were within the wind farm's boundaries. The noise impact assessments were conducted at various points near the wind farm. The wind farm was designed using an International Standards Organization (ISO) noise propagation model and a 40 dBA to provide adequate setbacks. The study was conducted using 10 days of continuous measurements at selected points of a wind farm. Points of reception included points from 650 m to 800 m. Noise over 2 km was not thought to be contributed by the wind turbine. The nearest dwelling was 512 m from one of the farm's wind turbines. The study also considered ground factor, temperature, relative humidity, and the height of the receptors. Quebec noise level limits are 40 dBA at night, and 45 dBA during the day. Noise level limits are independent of wind speed. Measured noise contributions over 40 dBA were not observed during the measurement program. The wind turbines were only audible for 1 night out of the 30 night study period. It was concluded that the ISO noise propagation model is a reliable tool for conducting noise impact assessments. tabs., figs
2007-04-01
This report documents a study to investigate human response to the low-frequency : content of aviation noise, or low-frequency noise (LFN). The study comprised field : measurements and laboratory studies. The major findings were: : 1. Start-of-takeof...
Noise Pollution, Teachers' Edition.
O'Donnell, Patrick A.; Lavaroni, Charles W.
One of three in a series about pollution, this teacher's guide for a unit on noise pollution is designed for use in junior high school grades. It offers suggestions for extending the information and activities contained in the textual material for students. Chapter 1 discusses the problem of noise pollution and involves students in processes of…
Symptoms Low white blood cell count By Mayo Clinic Staff A low white blood cell count (leukopenia) is a decrease ... of white blood cell (neutrophil). The definition of low white blood cell count varies from one medical ...
Van der Gugten, J; Slangen, J L; de Boer, S.F.
Plasma noradrenaline (NA), adrenaline (A) and corticosterone (CS) increases were determined in individual rats subjected to either 20 regularly or irregularly scheduled white-noise stimulations (4 min, 100 dBA). Blood was frequently sampled during the first and twentieth noise exposure, and during a
International Nuclear Information System (INIS)
Andersen, B.; Larsen, P.
1993-01-01
Denmark has 3200 wind turbines with an installed maximum capacity of 418MW. The most important Danish research projects into wind turbine noise and the main results are listed. These date from 1983. Two comprehensive studies are currently in progress. The first is an analytical and empirical investigation of aerodynamic noise from wind turbine rotors and has so far dealt mainly with tip noise. The measurement method, using a hard board mounted microphone on the ground near the turbine, is described. Four different tip designs have been tested. Some examples of reference sound power level spectra for three of the designs are presented. During the past two years a computerbased data acquisition system has been used for real-time determination of sound power levels. The second study, which has just commenced, is on annoyance from wind turbine noise. It will include noise measurements, masking calculations and a social survey on the perceived nuisance. (UK)
International Nuclear Information System (INIS)
Andersen, B.; Jakobsen, J.
1992-11-01
Based on a previous project concerning the calculation of the amount of noise emanating from wind turbine arrays, this one examines the subject further by investigating whether there could be significant differences in the amount of noise made by individual wind turbines in an array, and whether the noise is transmitted in varying directions - so that when it is carried in the same direction as the wind blows it would appear to be louder. The aim was also to determine whether the previously used method of calculation lacked precision. It was found that differences in noise niveaux related to individual wind turbines were insignificant and that noise was not so loud when it was not borne in the direction of the wind. It was necessary to change the method of calculation as reckoning should include the influence of the terrain, wind velocity and distance. The measuring and calculation methods are exemplified and the resulting measurements are presented in detail. (AB)
Reactor noise monitoring device
International Nuclear Information System (INIS)
Yamanaka, Hiroto.
1990-01-01
The present invention concerns a reactor noise monitoring device by detecting abnormal sounds in background noises. Vibration sounds detected by accelerometers are applied to a loose parts detector. The detector generates high alarm if there are sudden impact sounds in the background noises and applies output signals to an accumulation device. If there is slight impact sounds in the vicinity of any of the accelerometers, the accumulation device accumulates the abnormal sounds assumed to be generated from an identical site while synchronizing the waveforms for all of the channels. Then, the device outputs signals in which the background noises are cancelled, as detection signals. Therefore, S/N ratio can be improved and the abnormal sounds contained in the background noises can be detected, to thereby improve the accuracy for estimating the position where the abnormal sounds are generated. (I.S.)
Positive effects of noise on cognitive performance: Explaining the moderate brain arousal model
Söderlund, Göran; sikström, Sverker
2008-01-01
Distractors and environmental noise has long been regarded as detrimental for different kinds of cognitive processing. In particular children with Attention Deficit Hyperactivity Disorder (ADHD) are extremely sensitive to distraction from task irrelevant stimuli. However, recently the opposite has been shown in an empirical study by Söderlund et al. (2007). Exposure to auditory white noise facilitated cognitive performance in ADHD children whereas control children performed worse in the noise...
Noise-induced attractor annihilation in the delayed feedback logistic map
International Nuclear Information System (INIS)
Pisarchik, A.N.; Martínez-Zérega, B.E.
2013-01-01
We study dynamics of the bistable logistic map with delayed feedback, under the influence of white Gaussian noise and periodic modulation applied to the variable. This system may serve as a model to describe population dynamics under finite resources in noisy environment with seasonal fluctuations. While a very small amount of noise has no effect on the global structure of the coexisting attractors in phase space, an intermediate noise totally eliminates one of the attractors. Slow periodic modulation enhances the attractor annihilation.
Dimensioning BCH codes for coherent DQPSK systems with laser phase noise and cycle slips
DEFF Research Database (Denmark)
Leong, Miu Yoong; Larsen, Knud J.; Jacobsen, Gunnar
2014-01-01
Forward error correction (FEC) plays a vital role in coherent optical systems employing multi-level modulation. However, much of coding theory assumes that additive white Gaussian noise (AWGN) is dominant, whereas coherent optical systems have significant phase noise (PN) in addition to AWGN...... approach for a target post-FEC BER of 10-5. Codes dimensioned with our bivariate binomial model meet the target within 0.2-dB signal-to-noise ratio....
Realistic camera noise modeling with application to improved HDR synthesis
Goossens, Bart; Luong, Hiêp; Aelterman, Jan; Pižurica, Aleksandra; Philips, Wilfried
2012-12-01
Due to the ongoing miniaturization of digital camera sensors and the steady increase of the "number of megapixels", individual sensor elements of the camera become more sensitive to noise, even deteriorating the final image quality. To go around this problem, sophisticated processing algorithms in the devices, can help to maximally exploit the knowledge on the sensor characteristics (e.g., in terms of noise), and offer a better image reconstruction. Although a lot of research focuses on rather simplistic noise models, such as stationary additive white Gaussian noise, only limited attention has gone to more realistic digital camera noise models. In this article, we first present a digital camera noise model that takes several processing steps in the camera into account, such as sensor signal amplification, clipping, post-processing,.. We then apply this noise model to the reconstruction problem of high dynamic range (HDR) images from a small set of low dynamic range (LDR) exposures of a static scene. In literature, HDR reconstruction is mostly performed by computing a weighted average, in which the weights are directly related to the observer pixel intensities of the LDR image. In this work, we derive a Bayesian probabilistic formulation of a weighting function that is near-optimal in the MSE sense (or SNR sense) of the reconstructed HDR image, by assuming exponentially distributed irradiance values. We define the weighting function as the probability that the observed pixel intensity is approximately unbiased. The weighting function can be directly computed based on the noise model parameters, which gives rise to different symmetric and asymmetric shapes when electronic noise or photon noise is dominant. We also explain how to deal with the case that some of the noise model parameters are unknown and explain how the camera response function can be estimated using the presented noise model. Finally, experimental results are provided to support our findings.
Dilute: A code for studying beam evolution under rf noise
International Nuclear Information System (INIS)
Shih, H.; Ellison, J.A.; Schiesser, W.E.
1993-01-01
Longitudinal beam dynamics under rf noise has been modeled by Dome, Krinsky, and Wang using a diffusion-in-action PDE. If the primary interest is the evolution of the beam in action, it is much simpler to integrate the model PDE than to undertake tracking simulations. Here we describe the code that we developed to solve the model PDE using the numerical Method of Lines. Features of the code include (1) computation of the distribution in action for the initial beam from a Gaussian or user-supplied distribution in longitudinal phase space, (2) computation of the diffusion coefficient for white noise or from a user-supplied spectral density for non-white noise, (3) discretization of the model PDE using finite-difference or Galerkin finite-element approximations with a uniform or non-uniform grid, and (4) integration of the system of ODEs in time by the solver RKF45 or a user-supplied ODE solver
Effects of background noise on total noise annoyance
Willshire, K. F.
1987-01-01
Two experiments were conducted to assess the effects of combined community noise sources on annoyance. The first experiment baseline relationships between annoyance and noise level for three community noise sources (jet aircraft flyovers, traffic and air conditioners) presented individually. Forty eight subjects evaluated the annoyance of each noise source presented at four different noise levels. Results indicated the slope of the linear relationship between annoyance and noise level for the traffic noise was significantly different from that of aircraft and of air conditioner noise, which had equal slopes. The second experiment investigated annoyance response to combined noise sources, with aircraft noise defined as the major noise source and traffic and air conditioner noise as background noise sources. Effects on annoyance of noise level differences between aircraft and background noise for three total noise levels and for both background noise sources were determined. A total of 216 subjects were required to make either total or source specific annoyance judgements, or a combination of the two, for a wide range of combined noise conditions.
Noise and Hearing Loss Prevention
... message, please visit this page: About CDC.gov . NOISE AND HEARING LOSS PREVENTION Language: English (US) Español ( ... when hazardous noise levels cannot be adequately reduced. Noise and Hearing Loss on the NIOSH Science Blog ...
Handbook Of Noise And Vibration
International Nuclear Information System (INIS)
1995-12-01
This book is about noise and vibration. The first chapter has explanations of noise such as basic of sound, influence of noise, assessment of noise, measurement of prevention of noise and technology, case of noise measurement and soundproof. The second chapter describes vibration with outline, theory of vibration, interpretation of vibration, measurement for reduction of vibration, case of design of protection against vibration. It deals with related regulation and method of measurement.
Brain-stem evoked potentials and noise effects in seagulls.
Counter, S A
1985-01-01
Brain-stem auditory evoked potentials (BAEP) recorded from the seagull were large-amplitude, short-latency, vertex-positive deflections which originate in the eighth nerve and several brain-stem nuclei. BAEP waveforms were similar in latency and configurations to that reported for certain other lower vertebrates and some mammals. BAEP recorded at several pure tone frequencies throughout the seagull's auditory spectrum showed an area of heightened auditory sensitivity between 1 and 3 kHz. This range was also found to be the primary bandwidth of the vocalization output of young seagulls. Masking by white noise and pure tones had remarkable effects on several parameters of the BAEP. In general, the tone- and click-induced BAEP were either reduced or obliterated by both pure tone and white noise maskers of specific signal to noise ratios and high intensity levels. The masking effects observed in this study may be related to the manner in which seagulls respond to intense environmental noise. One possible conclusion is that intense environmental noise, such as aircraft engine noise, may severely alter the seagull's localization apparatus and induce sonogenic stress, both of which could cause collisions with low-flying aircraft.
CSIR Research Space (South Africa)
Ferreira, T.M
1973-01-01
Full Text Available or (by remaining at the 'alarm' level) prevents us from sleeping or resting. Some noise comes into buildings from outside, such as when a passing jet plane drowns a telephone conversation or when traffic noise prevents one from hearing an interesting... on aircraft that make too much noise. Motor cars, buses, buzz-bikes and vacuum deaners can be effectively quietened but until now the public has not been prepared to pay the price of legislation. Also, many young sports-car enthusiasts still think...
Hanafy, Sherif M.
2015-08-19
We use controlled noise seismology (CNS) to generate surface waves, where we continuously record seismic data while generating artificial noise along the profile line. To generate the CNS data we drove a vehicle around the geophone line and continuously recorded the generated noise. The recorded data set is then correlated over different time windows and the correlograms are stacked together to generate the surface waves. The virtual shot gathers reveal surface waves with moveout velocities that closely approximate those from active source shot gathers.
Hanafy, Sherif M.; AlTheyab, Abdullah; Schuster, Gerard T.
2015-01-01
We use controlled noise seismology (CNS) to generate surface waves, where we continuously record seismic data while generating artificial noise along the profile line. To generate the CNS data we drove a vehicle around the geophone line and continuously recorded the generated noise. The recorded data set is then correlated over different time windows and the correlograms are stacked together to generate the surface waves. The virtual shot gathers reveal surface waves with moveout velocities that closely approximate those from active source shot gathers.
Anti-deterministic behaviour of discrete systems that are less predictable than noise
Urbanowicz, Krzysztof; Kantz, Holger; Holyst, Janusz A.
2005-05-01
We present a new type of deterministic dynamical behaviour that is less predictable than white noise. We call it anti-deterministic (AD) because time series corresponding to the dynamics of such systems do not generate deterministic lines in recurrence plots for small thresholds. We show that although the dynamics is chaotic in the sense of exponential divergence of nearby initial conditions and although some properties of AD data are similar to white noise, the AD dynamics is in fact, less predictable than noise and hence is different from pseudo-random number generators.
International Nuclear Information System (INIS)
Holland, B.A.
1987-01-01
The diagnosis of white matter abnormalities was revolutionized by the advent of computed tomography (CT), which provided a noninvasive method of detection and assessment of progression of a variety of white matter processes. However, the inadequacies of CT were recognized early, including its relative insensitivity to small foci of abnormal myelin in the brain when correlated with autopsy findings and its inability to image directly white matter diseases of the spinal cord. Magnetic resonance imaging (MRI), on the other hand, sensitive to the slight difference in tissue composition of normal gray and white matter and to subtle increase in water content associated with myelin disorders, is uniquely suited for the examination of white matter pathology. Its clinical applications include the evaluation of the normal process of myelination in childhood and the various white matter diseases, including disorders of demyelination and dysmyelination
75 FR 65415 - White House Initiative on Educational Excellence for Hispanics
2010-10-22
... Part II The President Executive Order 13555--White House Initiative on Educational Excellence for... Order 13555 of October 19, 2010 White House Initiative on Educational Excellence for Hispanics By the... will be substantially enhanced by improving educational outcomes for Hispanics. Sec. 2. White House...
Acoustic ambient noise recorder
Digital Repository Service at National Institute of Oceanography (India)
Saran, A.K.; Navelkar, G.S.; Almeida, A.M.; More, S.R.; Chodankar, P.V.; Murty, C.S.
with a robust outfit that can withstand high pressures and chemically corrosion resistant materials. Keeping these considerations in view, a CMOS micro-controller-based marine acoustic ambient noise recorder has been developed with a real time clock...
Indian Academy of Sciences (India)
First page Back Continue Last page Overview Graphics. Full FEXT Cancellation. Expectation Maximization based Algorithms. Partial Cancellation. Optimal Choice of what to Cancel and what not to! Alien Noise Cancellation. Efficient Crosstalk channel estimation. In addition:
National Research Council Canada - National Science Library
Maidanik, G
2002-01-01
The induced noise control parameter is defined in terms of the ratio of the stored energy in a master dynamic system, when it is coupled to an adjunct dynamic system, to that stored energy when the coupling is absent...
The influence of continuous and intermittent traffic noise on sleep
Eberhardt, J. L.; Stråle, L.-O.; Berlin, M. H.
1987-08-01
The effects of road traffic noise on sleep were studied in the laboratory using nine young male adults (aged 20-26). The subjects were exposed to noise with different temporal characteristics: (i) continuous traffic noise of 36 dB(A) or 45 dB(A), (ii) intermittent noise of 50 truck passages with L pmax = 45 dB(A) ( L eq = 29 dB(A)) or L pmax = 55 dB(A) ( L eq = 36 dB(A)), and (iii) a combination of continuous (45 dB(A)) and intermittent ( L pmax = 55 dB(A)) traffic noise. For one noise condition (intermittent 55 dB(A)) the effect of the use of ear plugs was also studied. The intermittent noise of L pmax = 45 dB(A) caused transitions towards lighter sleep, whereas 55 dB(A) was needed to induce awakening effects. It could be shown that the probability for arousal reactions depends on the emergence of the noise peaks from the background, rather than the absolute noise peak level. Continuous traffic noise of 45 dB(A) caused REM sleep deficits, while intermittent traffic noise of L pmax = 45 dB(A) caused stage III+IV deficits. The night with ear plugs was virtually undisturbed. After nights with REM sleep deficits the subjective sleep quality was rated lower and mood was influenced adversely. For the types of exposure used in the present investigation L eq alone is not an adequate descriptor of the noise dose, relating to the sleep disturbances observed. From the present experiment, together with other existing data, it might be concluded that the WHO recommendation of L eq = 35 dB(A) is adequate, but should be supplemented with a maximum noise level, as expressed for example in L pmax or LI, that should not be exceeded.
''1/f noise'' in music: Music from 1/f noise
Energy Technology Data Exchange (ETDEWEB)
Voss, R.F.; Clarke, J.
1978-01-01
The spectral density of fluctuations in the audio power of many musical selections and of English speech varies approximately as 1/f (f is the frequency) down to a frequency of 5 x 10/sup -4/ Hz. This result implies that the audio-power fluctuations are correlated over all times in the same manner as ''1/f noise'' in electronic components. The frequency fluctuations of music also have a 1/f spectral density at frequencies down to the inverse of the length of the piece of music. The frequency fluctuations of English speech have a quite different behavior, with a single characteristic time of about 0.1 s, the average length of a syllable. The observations on music suggest that 1/f noise is a good choice for stochastic composition. Compositions in which the frequency and duration of each note were determined by 1/f noise sources sounded pleasing. Those generated by white-noise sources sounded too random, while those generated by 1/f/sup 2/ noise sounded too correlated.
Neutron noise analysis for malfunction diagnosis at sodium cooled reactors
International Nuclear Information System (INIS)
Hoppe, P.
1978-09-01
For the investigation of the potential use of neutron noise analysis at sodium cooled power reactors, measurements have been performed at the KNK I reactor over a period of 18 month under different operational conditions. The signal fluctuations of the following tranducers have been recorded: In-core and Ex-core neutron detectors, temperature-, flow-, pressure-, vibration- and acoustic sensors. These extensive measurements have been analyzed in the frequency range from 0,001 Hz to 1000 Hz with all currently known methods for the identification of noise sources. The following results have been found: - Neutron noise for f 20 Hz the white detection noise prevails. In the region from 1 Hz to 20 Hz the vibrations of core components contribute to neutron noise. - Neutron noise is influenced by the state of the plant. - The contributions to neutron noise due to the fluctuations of coolant flow and inlet temperature are small compared to those produced by the movements of the control rod initiated by the reactor control system. The quantitatively unidentifiable amount of reactivity fluctuations (0,6 time-dependent thermal bowing of the core. With respect to these results and by calculation of the neutron noise patterns to be expected for the SNR 300, the following possible applications for neutron noise analysis have been found: By means of neutron noise analysis only reactivity fluctuations can be identified and supervised which are produced by time dependent changes of the core geometry. Furthermore neutron noise analysis is well suited for a sensitive detection of control rod vibrations and of local sodium boiling. Finally it can be used for the surveillance of the proper functioning of the reactor control system and of the control rod drive mechanism. (orig./HP) 891 HP [de
Ji, Yanju; Li, Dongsheng; Yu, Mingmei; Wang, Yuan; Wu, Qiong; Lin, Jun
2016-05-01
The ground electrical source airborne transient electromagnetic system (GREATEM) on an unmanned aircraft enjoys considerable prospecting depth, lateral resolution and detection efficiency, etc. In recent years it has become an important technical means of rapid resources exploration. However, GREATEM data are extremely vulnerable to stationary white noise and non-stationary electromagnetic noise (sferics noise, aircraft engine noise and other human electromagnetic noises). These noises will cause degradation of the imaging quality for data interpretation. Based on the characteristics of the GREATEM data and major noises, we propose a de-noising algorithm utilizing wavelet threshold method and exponential adaptive window width-fitting. Firstly, the white noise is filtered in the measured data using the wavelet threshold method. Then, the data are segmented using data window whose step length is even logarithmic intervals. The data polluted by electromagnetic noise are identified within each window based on the discriminating principle of energy detection, and the attenuation characteristics of the data slope are extracted. Eventually, an exponential fitting algorithm is adopted to fit the attenuation curve of each window, and the data polluted by non-stationary electromagnetic noise are replaced with their fitting results. Thus the non-stationary electromagnetic noise can be effectively removed. The proposed algorithm is verified by the synthetic and real GREATEM signals. The results show that in GREATEM signal, stationary white noise and non-stationary electromagnetic noise can be effectively filtered using the wavelet threshold-exponential adaptive window width-fitting algorithm, which enhances the imaging quality.
International Nuclear Information System (INIS)
Dybiec, Bartłomiej; Gudowska-Nowak, Ewa
2009-01-01
A standard approach to analysis of noise-induced effects in stochastic dynamics assumes a Gaussian character of the noise term describing interaction of the analyzed system with its complex surroundings. An additional assumption about the existence of timescale separation between the dynamics of the measured observable and the typical timescale of the noise allows external fluctuations to be modeled as temporally uncorrelated and therefore white. However, in many natural phenomena the assumptions concerning the above mentioned properties of 'Gaussianity' and 'whiteness' of the noise can be violated. In this context, in contrast to the spatiotemporal coupling characterizing general forms of non-Markovian or semi-Markovian Lévy walks, so called Lévy flights correspond to the class of Markov processes which can still be interpreted as white, but distributed according to a more general, infinitely divisible, stable and non-Gaussian law. Lévy noise-driven non-equilibrium systems are known to manifest interesting physical properties and have been addressed in various scenarios of physical transport exhibiting a superdiffusive behavior. Here we present a brief overview of our recent investigations aimed at understanding features of stochastic dynamics under the influence of Lévy white noise perturbations. We find that the archetypal phenomena of noise-induced ordering are robust and can be detected also in systems driven by memoryless, non-Gaussian, heavy-tailed fluctuations with infinite variance