Frequency domain analysis of errors in cross-correlations of ambient seismic noise

NASA Astrophysics Data System (ADS)

Liu, Xin; Ben-Zion, Yehuda; Zigone, Dimitri

2016-12-01

We analyse random errors (variances) in cross-correlations of ambient seismic noise in the frequency domain, which differ from previous time domain methods. Extending previous theoretical results on ensemble averaged cross-spectrum, we estimate confidence interval of stacked cross-spectrum of finite amount of data at each frequency using non-overlapping windows with fixed length. The extended theory also connects amplitude and phase variances with the variance of each complex spectrum value. Analysis of synthetic stationary ambient noise is used to estimate the confidence interval of stacked cross-spectrum obtained with different length of noise data corresponding to different number of evenly spaced windows of the same duration. This method allows estimating Signal/Noise Ratio (SNR) of noise cross-correlation in the frequency domain, without specifying filter bandwidth or signal/noise windows that are needed for time domain SNR estimations. Based on synthetic ambient noise data, we also compare the probability distributions, causal part amplitude and SNR of stacked cross-spectrum function using one-bit normalization or pre-whitening with those obtained without these pre-processing steps. Natural continuous noise records contain both ambient noise and small earthquakes that are inseparable from the noise with the existing pre-processing steps. Using probability distributions of random cross-spectrum values based on the theoretical results provides an effective way to exclude such small earthquakes, and additional data segments (outliers) contaminated by signals of different statistics (e.g. rain, cultural noise), from continuous noise waveforms. This technique is applied to constrain values and uncertainties of amplitude and phase velocity of stacked noise cross-spectrum at different frequencies, using data from southern California at both regional scale (˜35 km) and dense linear array (˜20 m) across the plate-boundary faults. A block bootstrap resampling method is used to account for temporal correlation of noise cross-spectrum at low frequencies (0.05-0.2 Hz) near the ocean microseismic peaks.

Collective excitations and ultrafast dipolar solvation dynamics in water-ethanol binary mixture

NASA Astrophysics Data System (ADS)

Hazra, Milan K.; Bagchi, Biman

2018-03-01

In order to understand the intermolecular vibrational spectrum and the collective excitations of water-ethanol binary mixture, we investigate the density of states and the power spectrum using computer simulations aided by theory. We investigate in particular the spectra at intermediate to low frequencies (a few hundreds to few tens of cm-1) by calculating (i) the density of states from quenched normal modes, (ii) the power spectrum from velocity time correlation function, and (iii) the far infrared and dielectric spectra (that is, the Cole-Cole plot) from the total dipole moment time correlation function. The different spectra are in broad agreement with each other and at the same time reveal unique characteristics of the water-ethanol mixture. Inverse participation ratio reveals several interesting features. Libration of pure ethanol is more localized than that of pure water. With increasing ethanol content, we observe localization of the collective libration mode as well as of the hindered translational and rotational mode. An interesting mixing between the libration of water and ethanol is observed. Solvation dynamics of tryptophan measured by equilibrium energy fluctuation time correlation function show surprisingly strong non-linear dependence on composition that can be tested against experiments.

Collective excitations and ultrafast dipolar solvation dynamics in water-ethanol binary mixture.

PubMed

Hazra, Milan K; Bagchi, Biman

2018-03-21

In order to understand the intermolecular vibrational spectrum and the collective excitations of water-ethanol binary mixture, we investigate the density of states and the power spectrum using computer simulations aided by theory. We investigate in particular the spectra at intermediate to low frequencies (a few hundreds to few tens of cm -1 ) by calculating (i) the density of states from quenched normal modes, (ii) the power spectrum from velocity time correlation function, and (iii) the far infrared and dielectric spectra (that is, the Cole-Cole plot) from the total dipole moment time correlation function. The different spectra are in broad agreement with each other and at the same time reveal unique characteristics of the water-ethanol mixture. Inverse participation ratio reveals several interesting features. Libration of pure ethanol is more localized than that of pure water. With increasing ethanol content, we observe localization of the collective libration mode as well as of the hindered translational and rotational mode. An interesting mixing between the libration of water and ethanol is observed. Solvation dynamics of tryptophan measured by equilibrium energy fluctuation time correlation function show surprisingly strong non-linear dependence on composition that can be tested against experiments.

Calculation of power spectrums from digital time series with missing data points

NASA Technical Reports Server (NTRS)

Murray, C. W., Jr.

1980-01-01

Two algorithms are developed for calculating power spectrums from the autocorrelation function when there are missing data points in the time series. Both methods use an average sampling interval to compute lagged products. One method, the correlation function power spectrum, takes the discrete Fourier transform of the lagged products directly to obtain the spectrum, while the other, the modified Blackman-Tukey power spectrum, takes the Fourier transform of the mean lagged products. Both techniques require fewer calculations than other procedures since only 50% to 80% of the maximum lags need be calculated. The algorithms are compared with the Fourier transform power spectrum and two least squares procedures (all for an arbitrary data spacing). Examples are given showing recovery of frequency components from simulated periodic data where portions of the time series are missing and random noise has been added to both the time points and to values of the function. In addition the methods are compared using real data. All procedures performed equally well in detecting periodicities in the data.

Self spectrum window method in wigner-ville distribution.

PubMed

Liu, Zhongguo; Liu, Changchun; Liu, Boqiang; Lv, Yangsheng; Lei, Yinsheng; Yu, Mengsun

2005-01-01

Wigner-Ville distribution (WVD) is an important type of time-frequency analysis in biomedical signal processing. The cross-term interference in WVD has a disadvantageous influence on its application. In this research, the Self Spectrum Window (SSW) method was put forward to suppress the cross-term interference, based on the fact that the cross-term and auto-WVD- terms in integral kernel function are orthogonal. With the Self Spectrum Window (SSW) algorithm, a real auto-WVD function was used as a template to cross-correlate with the integral kernel function, and the Short Time Fourier Transform (STFT) spectrum of the signal was used as window function to process the WVD in time-frequency plane. The SSW method was confirmed by computer simulation with good analysis results. Satisfactory time- frequency distribution was obtained.

Shot noise cross-correlation functions and cross spectra - Implications for models of QPO X-ray sources

NASA Technical Reports Server (NTRS)

Shibazaki, N.; Elsner, R. F.; Bussard, R. W.; Ebisuzaki, T.; Weisskopf, M. C.

1988-01-01

The cross-correlation functions (CCFs) and cross spectra expected for quasi-periodic oscillation (QPO) shot noise models are calculated under various assumptions, and the results are compared to observations. Effects due to possible coherence of the QPO oscillations are included. General formulas for the cross spectrum, the cross-phase spectrum, and the time-delay spectrum for QPO shot models are calculated and discussed. It is shown that the CCFs, cross spectra, and power spectra observed for Cyg X-e2 imply that the spectrum of the shots evolves with time, with important implications for the interpretation of these functions as well as of observed average energy spectra. The possible origins for the observed hard lags are discussed, and some physical difficulties for the Comptonization model are described. Classes of physical models for QPO sources are briefly addressed, and it is concluded that models involving shot formation at the surface of neutron stars are favored by observation.

Long-time correlation for the chaotic orbit in the two-wave Hamiltonian

NASA Astrophysics Data System (ADS)

Hatori, Tadatsugu; Irie, Haruyuki

1987-03-01

The time correlation function of velocity is found to decay with the power law for the orbit governed by a Hamiltonian, H=v sup 2/2 - Mcosx - Pcos (k(x-t)). The renormalization group technique can predict the power of decay for the correlation function defined by the ensemble average. The power spectrum becomes the 1/f-type for a special case.

SAW correlator spread spectrum receiver

DOEpatents

Brocato, Robert W

2014-04-01

A surface acoustic wave (SAW) correlator spread-spectrum (SS) receiver is disclosed which utilizes a first demodulation stage with a chip length n and a second demodulation stage with a chip length m to decode a transmitted SS signal having a code length l=n.times.m which can be very long (e.g. up to 2000 chips or more). The first demodulation stage utilizes a pair of SAW correlators which demodulate the SS signal to generate an appropriate code sequence at an intermediate frequency which can then be fed into the second demodulation stage which can be formed from another SAW correlator, or by a digital correlator. A compound SAW correlator comprising two input transducers and a single output transducer is also disclosed which can be used to form the SAW correlator SS receiver, or for use in processing long code length signals.

Schizotypal Perceptual Aberrations of Time: Correlation between Score, Behavior and Brain Activity

PubMed Central

Arzy, Shahar; Mohr, Christine; Molnar-Szakacs, Istvan; Blanke, Olaf

2011-01-01

A fundamental trait of the human self is its continuum experience of space and time. Perceptual aberrations of this spatial and temporal continuity is a major characteristic of schizophrenia spectrum disturbances – including schizophrenia, schizotypal personality disorder and schizotypy. We have previously found the classical Perceptual Aberration Scale (PAS) scores, related to body and space, to be positively correlated with both behavior and temporo-parietal activation in healthy participants performing a task involving self-projection in space. However, not much is known about the relationship between temporal perceptual aberration, behavior and brain activity. To this aim, we composed a temporal Perceptual Aberration Scale (tPAS) similar to the traditional PAS. Testing on 170 participants suggested similar performance for PAS and tPAS. We then correlated tPAS and PAS scores to participants' performance and neural activity in a task of self-projection in time. tPAS scores correlated positively with reaction times across task conditions, as did PAS scores. Evoked potential mapping and electrical neuroimaging showed self-projection in time to recruit a network of brain regions at the left anterior temporal cortex, right temporo-parietal junction, and occipito-temporal cortex, and duration of activation in this network positively correlated with tPAS and PAS scores. These data demonstrate that schizotypal perceptual aberrations of both time and space, as reflected by tPAS and PAS scores, are positively correlated with performance and brain activation during self-projection in time in healthy individuals along the schizophrenia spectrum. PMID:21267456

Multi-channel dynamics in high harmonic generation of aligned CO2: ab initio analysis with time-dependent B-spline algebraic diagrammatic construction.

PubMed

Ruberti, M; Decleva, P; Averbukh, V

2018-03-28

Here we present a fully ab initio study of the high-order harmonic generation (HHG) spectrum of aligned CO 2 molecules. The calculations have been performed by using the molecular time-dependent (TD) B-spline algebraic diagrammatic construction (ADC) method. We quantitatively study how the sub-cycle laser-driven multi-channel dynamics, as reflected in the position of the dynamical minimum in the HHG spectrum, is affected by the full inclusion of both correlation-driven and laser-driven dipole interchannel couplings. We calculate channel-resolved spectral intensities as well as the phase differences between contributions of the different ionization-recombination channels to the total HHG spectrum. Our results show that electron correlation effectively controls the relative contributions of the different channels to the total HHG spectrum, leading to the opening of the new ones (1 2 Π u , 1 2 Σ), previously disregarded for the aligned molecular setup. We conclude that inclusion of many-electron effects into the theoretical interpretation of molecular HHG spectra is essential in order to correctly extract ultrafast electron dynamics using HHG spectroscopy.

Application of unsymmetrical indirect covariance NMR methods to the computation of the (13)C <--> (15)N HSQC-IMPEACH and (13)C <--> (15)N HMBC-IMPEACH correlation spectra.

PubMed

Martin, Gary E; Hilton, Bruce D; Irish, Patrick A; Blinov, Kirill A; Williams, Antony J

2007-10-01

Utilization of long-range (1)H--(15)N heteronuclear chemical shift correlation has continually grown in importance since the first applications were reported in 1995. More recently, indirect covariance NMR methods have been introduced followed by the development of unsymmetrical indirect covariance processing methods. The latter technique has been shown to allow the calculation of hyphenated 2D NMR data matrices from more readily acquired nonhyphenated 2D NMR spectra. We recently reported the use of unsymmetrical indirect covariance processing to combine (1)H--(13)C GHSQC and (1)H--(15)N GHMBC long-range spectra to yield a (13)C--(15)N HSQC-HMBC chemical shift correlation spectrum that could not be acquired in a reasonable period of time without resorting to (15)N-labeled molecules. We now report the unsymmetrical indirect covariance processing of (1)H--(13)C GHMBC and (1)H--(15)N IMPEACH spectra to afford a (13)C--(15)N HMBC-IMPEACH spectrum that has the potential to span as many as six to eight bonds. Correlations for carbon resonances long-range coupled to a protonated carbon in the (1)H--(13)C HMBC spectrum are transferred via the long-range (1)H--(15)N coupling pathway in the (1)H--(15)N IMPEACH spectrum to afford a much broader range of correlation possibilities in the (13)C--(15)N HMBC-IMPEACH correlation spectrum. The indole alkaloid vincamine is used as a model compound to illustrate the application of the method. (c) 2007 John Wiley & Sons, Ltd.

Partition-free theory of time-dependent current correlations in nanojunctions in response to an arbitrary time-dependent bias

NASA Astrophysics Data System (ADS)

Ridley, Michael; MacKinnon, Angus; Kantorovich, Lev

2017-04-01

Working within the nonequilibrium Green's function formalism, a formula for the two-time current correlation function is derived for the case of transport through a nanojunction in response to an arbitrary time-dependent bias. The one-particle Hamiltonian and the wide-band limit approximation are assumed, enabling us to extract all necessary Green's functions and self-energies for the system, extending the analytic work presented previously [Ridley et al., Phys. Rev. B 91, 125433 (2015), 10.1103/PhysRevB.91.125433]. We show that our expression for the two-time correlation function generalizes the Büttiker theory of shot and thermal noise on the current through a nanojunction to the time-dependent bias case including the transient regime following the switch-on. Transient terms in the correlation function arise from an initial state that does not assume (as is usually done) that the system is initially uncoupled, i.e., our approach is partition free. We show that when the bias loses its time dependence, the long-time limit of the current correlation function depends on the time difference only, as in this case an ideal steady state is reached. This enables derivation of known results for the single-frequency power spectrum and for the zero-frequency limit of this power spectrum. In addition, we present a technique which facilitates fast calculations of the transient quantum noise, valid for arbitrary temperature, time, and voltage scales. We apply this formalism to a molecular wire system for both dc and ac biases, and find a signature of the traversal time for electrons crossing the wire in the time-dependent cross-lead current correlations.

Pulse transmission receiver with higher-order time derivative pulse correlator

DOEpatents

Dress, Jr., William B.; Smith, Stephen F.

2003-09-16

Systems and methods for pulse-transmission low-power communication modes are disclosed. A pulse transmission receiver includes: a higher-order time derivative pulse correlator; a demodulation decoder coupled to the higher-order time derivative pulse correlator; a clock coupled to the demodulation decoder; and a pseudorandom polynomial generator coupled to both the higher-order time derivative pulse correlator and the clock. The systems and methods significantly reduce lower-frequency emissions from pulse transmission spread-spectrum communication modes, which reduces potentially harmful interference to existing radio frequency services and users and also simultaneously permit transmission of multiple data bits by utilizing specific pulse shapes.

Coherent changes of multifractal properties of continuous acoustic emission at failure of heterogeneous materials

NASA Astrophysics Data System (ADS)

Panteleev, Ivan; Bayandin, Yuriy; Naimark, Oleg

2017-12-01

This work performs a correlation analysis of the statistical properties of continuous acoustic emission recorded in different parts of marble and fiberglass laminate samples under quasi-static deformation. A spectral coherent measure of time series, which is a generalization of the squared coherence spectrum on a multidimensional series, was chosen. The spectral coherent measure was estimated in a sliding time window for two parameters of the acoustic emission multifractal singularity spectrum: the spectrum width and the generalized Hurst exponent realizing the maximum of the singularity spectrum. It is shown that the preparation of the macrofracture focus is accompanied by the synchronization (coherent behavior) of the statistical properties of acoustic emission in allocated frequency intervals.

Performance of wind turbines in a turbulent atmosphere

NASA Technical Reports Server (NTRS)

Sundar, R. M.; Sullivan, J. P.

1981-01-01

The effect of atmospheric turbulence on the power fluctuations of large wind turbines was studied. The significance of spatial non-uniformities of the wind is emphasized. The turbulent wind with correlation in time and space is simulated on the computer by Shinozukas method. The wind turbulence is modelled according to the Davenport spectrum with an exponential spatial correlation function. The rotor aerodynamics is modelled by simple blade element theory. Comparison of the spectrum of power output signal between 1-D and 3-D turbulence, shows the significant power fluctuations centered around the blade passage frequency.

Lensing as a probe of early universe: from CMB to galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hassani, Farbod; Baghram, Shant; Firouzjahi, Hassan, E-mail: farbod@physics.sharif.edu, E-mail: baghram@sharif.edu, E-mail: firouz@ipm.ir

The Cosmic Microwave Background (CMB) radiation lensing is a promising tool to study the physics of early universe. In this work we probe the imprints of deviations from isotropy and scale invariance of primordial curvature perturbation power spectrum on CMB lensing potential and convergence. Specifically, we consider a scale-dependent hemispherical asymmetry in primordial power spectrum. We show that the CMB lensing potential and convergence and also the cross-correlation of the CMB lensing and late time galaxy convergence can probe the amplitude and the scale dependence of the dipole modulation. As another example, we consider a primordial power spectrum with localmore » feature. We show that the CMB lensing and the cross-correlation of the CMB lensing and galaxy lensing can probe the amplitude and the shape of the local feature. We show that the cross correlation of CMB lensing convergence and galaxy lensing is capable to probe the effects of local features in power spectrum on smaller scales than the CMB lensing. Finally we showed that the current data can constrain the amplitude and moment dependence of dipole asymmetry.« less

Spectral analysis of the signal from the Laser Doppler Velocimeter - Turbulent flows.

NASA Technical Reports Server (NTRS)

Edwards, R. V.; Angus, J. C.; Dunning, J. W., Jr.

1973-01-01

A method for prediction and analysis of the spectrum of the signal from the Laser Doppler Velocimeter is presented. The results relate the heterodyne spectrum of the signal to the space-time correlation function for the turbulent transport of tracer particles in the fluid and to the characteristics of the optical system.

Wavepacket dynamics in one-dimensional system with long-range correlated disorder

NASA Astrophysics Data System (ADS)

Yamada, Hiroaki S.

2018-03-01

We numerically investigate dynamical property in the one-dimensional tight-binding model with long-range correlated disorder having power spectrum 1 /fα (α: spectrum exponent) generated by Fourier filtering method. For relatively small α <αc (=2) time-dependence of mean square displacement (MSD) of the initially localized wavepacket shows ballistic spread and localizes as time elapses. It is shown that α-dependence of the dynamical localization length determined by the MSD exhibits a simple scaling law in the localization regime for the relatively weak disorder strength W. Furthermore, scaled MSD by the dynamical localization length almost obeys an universal function from the ballistic to the localization regime in the various combinations of the parameters α and W.

Reynolds and Prandtl number scaling of viscous heating in isotropic turbulence

NASA Astrophysics Data System (ADS)

Pushkarev, Andrey; Balarac, Guillaume; Bos, Wouter J. T.

2017-08-01

Viscous heating is investigated using high-resolution direct numerical simulations. Scaling relations are derived and verified for different values of the Reynolds and Prandtl numbers. The scaling of the heat fluctuations is shown to depend on Lagrangian correlation times and on the scaling of dissipation-rate fluctuations. The convergence of the temperature spectrum to asymptotic scaling is observed to be slow, due to the broadband character of the temperature production spectrum and the slow convergence of the dissipation-rate spectrum to its asymptotic form.

Linearized spectrum correlation analysis for line emission measurements

NASA Astrophysics Data System (ADS)

Nishizawa, T.; Nornberg, M. D.; Den Hartog, D. J.; Sarff, J. S.

2017-08-01

A new spectral analysis method, Linearized Spectrum Correlation Analysis (LSCA), for charge exchange and passive ion Doppler spectroscopy is introduced to provide a means of measuring fast spectral line shape changes associated with ion-scale micro-instabilities. This analysis method is designed to resolve the fluctuations in the emission line shape from a stationary ion-scale wave. The method linearizes the fluctuations around a time-averaged line shape (e.g., Gaussian) and subdivides the spectral output channels into two sets to reduce contributions from uncorrelated fluctuations without averaging over the fast time dynamics. In principle, small fluctuations in the parameters used for a line shape model can be measured by evaluating the cross spectrum between different channel groupings to isolate a particular fluctuating quantity. High-frequency ion velocity measurements (100-200 kHz) were made by using this method. We also conducted simulations to compare LSCA with a moment analysis technique under a low photon count condition. Both experimental and synthetic measurements demonstrate the effectiveness of LSCA.

Noise characterization of a pulse train generated by actively mode-locked lasers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eliyahu, D.; Salvatore, R.A.; Yariv, A.

1996-07-01

We analyze the entire power spectrum of pulse trains generated by a continuously operating actively mode-locked laser in the presence of noise. We consider the effect of amplitude, pulse-shape, and timing-jitter fluctuations that are characterized by stationary processes. Effects of correlations between different parameters of these fluctuations are studied also. The nonstationary timing-jitter fluctuations of passively mode-locked lasers and their influence on the power spectrum is discussed as well. {copyright} {ital 1996 Optical Society of America.}

Sleep Disruption as a Correlate to Cognitive and Adaptive Behavior Problems in Autism Spectrum Disorders

ERIC Educational Resources Information Center

Taylor, Matthew A.; Schreck, Kimberly A.; Mulick, James A.

2012-01-01

Sleep problems associated with autism spectrum disorders (ASD) have been well documented, but less is known about the effects of sleep problems on day-time cognitive and adaptive performance in this population. Children diagnosed with autism or pervasive developmental disorder-not otherwise specified (PDD-NOS) (N = 335) from 1 to 10 years of age…

Physical activity, sedentary behavior and their correlates in children with Autism Spectrum Disorder: A systematic review

PubMed Central

Downing, Katherine; Rinehart, Nicole J.; Barnett, Lisa M.; May, Tamara; McGillivray, Jane A.; Papadopoulos, Nicole V.; Skouteris, Helen; Timperio, Anna

2017-01-01

Autism Spectrum Disorder affects up to 2.5% of children and is associated with harmful health outcomes (e.g. obesity). Low levels of physical activity and high levels of sedentary behaviors may contribute to harmful health outcomes. To systematically review the prevalence and correlates of physical activity and sedentary behaviors in children with Autism Spectrum Disorder, electronic databases (PsycINFO, SPORTDiscus, EMBASE, Medline) were searched from inception to November 2015. The review was registered with PROSPERO (CRD42014013849). Peer-reviewed, English language studies were included. Two reviewers screened potentially relevant articles. Outcomes of interest were physical activity and sedentary behaviour levels and their potential correlates. Data were collected and analysed in 2015. Of 35 included studies, 15 reported physical activity prevalence, 10 reported physical activity correlates, 18 reported sedentary behavior prevalence, and 10 reported sedentary behavior correlates. Estimates of children’s physical activity (34–166 mins/day, average 86 mins/day) and sedentary behavior (126–558 mins/day in screen time, average 271 mins/day; 428–750 mins/day in total sedentary behavior, average 479 mins/day) varied across studies. Age was consistently inversely associated, and sex inconsistently associated with physical activity. Age and sex were inconsistently associated with sedentary behavior. Sample sizes were small. All but one of the studies were classified as having high risk of bias. Few correlates have been reported in sufficient studies to provide overall estimates of associations. Potential correlates in the physical environment remain largely unexamined. This review highlights varying levels of physical activity and sedentary behavior in children with Autism Spectrum Disorder. Research is needed to consistently identify the correlates of these behaviors. There is a critical need for interventions to support healthy levels of these behaviors. PMID:28245224

The effect of blood acceleration on the ultrasound power Doppler spectrum

NASA Astrophysics Data System (ADS)

Matchenko, O. S.; Barannik, E. A.

2017-09-01

The purpose of the present work was to study the influence of blood acceleration and time window length on the power Doppler spectrum for Gaussian ultrasound beams. The work has been carried out on the basis of continuum model of the ultrasound scattering from inhomogeneities in fluid flow. Correlation function of fluctuations has been considered for uniformly accelerated scatterers, and the resulting power Doppler spectra have been calculated. It is shown that within the initial phase of systole uniformly accelerated slow blood flow in pulmonary artery and aorta tends to make the correlation function about 4.89 and 7.83 times wider, respectively, than the sensitivity function of typical probing system. Given peak flow velocities, the sensitivity function becomes, vice versa, about 4.34 and 3.84 times wider, respectively, then the correlation function. In these limiting cases, the resulting spectra can be considered as Gaussian. The optimal time window duration decreases with increasing acceleration of blood flow and equals to 11.62 and 7.54 ms for pulmonary artery and aorta, respectively. The width of the resulting power Doppler spectrum is shown to be defined mostly by the wave vector of the incident field, the duration of signal and the acceleration of scatterers in the case of low flow velocities. In the opposite case geometrical properties of probing field and the average velocity itself are more essential. In the sense of signal-noise ratio, the optimal duration of time window can be found. Abovementioned results may contribute to the improved techniques of Doppler ultrasound diagnostics of cardiovascular system.

Prevalence and correlates of screen-based media use among youths with autism spectrum disorders.

PubMed

Mazurek, Micah O; Shattuck, Paul T; Wagner, Mary; Cooper, Benjamin P

2012-08-01

Anecdotal reports indicate that individuals with autism spectrum disorders (ASD) are often preoccupied with television, computers, and video games (screen-based media). However, few studies have examined this issue. The current study examined screen-based media use among a large, nationally representative sample of youths participating in the National Longitudinal Transition Study-2 (NLTS2). The majority of youths with ASD (64.2%) spent most of their free time using non-social media (television, video games), while only 13.2% spent time on social media (email, internet chatting). Compared with other disability groups (speech/language impairments, learning disabilities, intellectual disabilities), rates of non-social media use were higher among the ASD group, and rates of social media use were lower. Demographic and symptom-specific correlates were also examined.

The effect of a hot, spherical scattering cloud on quasi-periodic oscillation behavior

NASA Astrophysics Data System (ADS)

Bussard, R. W.; Weisskopf, M. C.; Elsner, R. F.; Shibazaki, N.

1988-04-01

A Monte Carlo technique is used to investigate the effects of a hot electron scattering cloud surrounding a time-dependent X-ray source. Results are presented for the time-averaged emergent energy spectra and the mean residence time in the cloud as a function of energy. Moreover, after Fourier transforming the scattering Green's function, it is shown how the cloud affects both the observed power spectrum of a time-dependent source and the cross spectrum (Fourier transform of a cross correlation between energy bands). It is found that the power spectra intrinsic to the source are related to those observed by a relatively simple frequency-dependent multiplicative factor (a transmission function). The cloud can severely attenuate high frequencies in the power spectra, depending on optical depth, and, at lower frequencies, the transmission function has roughly a Lorentzian shape. It is also found that if the intrinsic energy spectrum is constant in time, the phase of the cross spectrum is determined entirely by scattering. Finally, the implications of the results for studies of the X-ray quasi-periodic oscillators are discussed.

Finite-Difference Time-Domain Analysis of Tapered Photonic Crystal Fiber

NASA Astrophysics Data System (ADS)

Ali, M. I. Md; Sanusidin, S. N.; Yusof, M. H. M.

2018-03-01

This paper brief about the simulation of tapered photonic crystal fiber (PCF) LMA-8 single-mode type based on correlation of scattering pattern at wavelength of 1.55 μm, analyzation of transmission spectrum at wavelength over the range of 1.0 until 2.5 μm and correlation of transmission spectrum with the refractive index change in photonic crystal holes with respect to taper size of 0.1 until 1.0 using Optiwave simulation software. The main objective is to simulate using Finite-Difference Time-Domain (FDTD) technique of tapered LMA-8 PCF and for sensing application by improving the capabilities of PCF without collapsing the crystal holes. The types of FDTD techniques used are scattering pattern and transverse transmission and principal component analysis (PCA) used as a mathematical tool to model the data obtained by MathCad software. The simulation results showed that there is no obvious correlation of scattering pattern at a wavelength of 1.55 μm, a correlation obtained between taper sizes with a transverse transmission and there is a parabolic relationship between the refractive index changes inside the crystal structure.

Multifractal detrended cross-correlation analysis on air pollutants of University of Hyderabad Campus, India

NASA Astrophysics Data System (ADS)

Manimaran, P.; Narayana, A. C.

2018-07-01

In this paper, we study the multifractal characteristics and cross-correlation behaviour of Air Pollution Index (API) time series data through multifractal detrended cross-correlation analysis method. We analyse the daily API records of nine air pollutants of the university of Hyderabad campus for a period of three years (2013-2016). The cross-correlation behaviour has been measured from the Hurst scaling exponents and the singularity spectrum quantitatively. From the results, it is found that the cross-correlation analysis shows anti-correlation behaviour for all possible 36 bivariate time series. We also observe the existence of multifractal nature in all the bivariate time series in which many of them show strong multifractal behaviour. In particular, the hazardous particulate matter PM2.5 and inhalable particulate matter PM10 shows anti-correlated behaviour with all air pollutants.

Estimation of the EEG power spectrum using MRI T(2) relaxation time in traumatic brain injury.

PubMed

Thatcher, R W; Biver, C; Gomez, J F; North, D; Curtin, R; Walker, R A; Salazar, A

2001-09-01

To study the relationship between magnetic resonance imaging (MRI) T(2) relaxation time and the power spectrum of the electroencephalogram (EEG) in long-term follow up of traumatic brain injury. Nineteen channel quantitative electroencephalograms or qEEG, tests of cognitive function and quantitative MRI T(2) relaxation times (qMRI) were measured in 18 mild to severe closed head injured outpatients 2 months to 4.6 years after injury and 11 normal controls. MRI T(2) and the Laplacian of T(2) were then correlated with the power spectrum of the scalp electrical potentials and current source densities of the qEEG. qEEG and qMRI T(2) were related by a frequency tuning with maxima in the alpha (8-12Hz) and the lower EEG frequencies (0.5-5Hz), which varied as a function of spatial location. The Laplacian of T(2) acted like a spatial-temporal "lens" by increasing the spatial-temporal resolution of correlation between 3-dimensional T(2) and the ear referenced alert but resting spontaneous qEEG. The severity of traumatic brain injury can be modeled by a linear transfer function that relates the molecular qMRI to qEEG resonant frequencies.

Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS

PubMed Central

Zhang, Rongchun; Ramamoorthy, Ayyalusamy

2016-01-01

Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and the use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D 1H/13C/1H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t1 and t3 periods, respectively. In addition to through-space and through-bond 13C/1H and 13C/13C chemical shift correlations, the 3D 1H/13C/1H experiment also provides a COSY-type 1H/1H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices (1H/1H chemical shift correlation spectrum) at different 13C chemical shift frequencies from the 3D 1H/13C/1H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D 1H/13C/1H experiment would be useful to study the structure and dynamics of a variety of chemical and biological solids. PMID:26801026

A psychometric study of the multidimensional fatigue inventory to assess fatigue in patients with schizophrenia spectrum disorders.

PubMed

Hedlund, Lena; Gyllensten, Amanda Lundvik; Hansson, Lars

2015-04-01

Fatigue is frequently reported by patients with mental illness. The multidimensional fatigue inventory (MFI-20) is a self-assessment instrument with 20 items including five dimensions of fatigue. The purpose of this study was to examine the test-retest reliability, internal consistency, convergent construct validity and feasibility of using MFI-20 in patients with schizophrenia spectrum disorders. Patients completed two self-assessment instruments, MFI-20 (n = 93) and Visual Analogue Scale (n = 79), twice within 1 week ± 2 days. Fifty-three patients also rated the feasibility of responding to the MFI-20 with a Likert scale. The test-retest reliability and validity were analysed by using Spearman's correlations and internal consistency by calculating Cronbach's α. The test-retest showed a correlation between .66 and .91 for all subscales of MFI. The internal consistency was .92. The analysis of convergent construct validity showed a correlation of .68 (time 1) and .77 (time 2). No item was systematically identified as being difficult to answer.

Comprehensive Analysis of RXTE Data from Cyg X-1. Spectral Index-Quasi-Periodic Oscillation Frequency-Luminosity Correlations

NASA Technical Reports Server (NTRS)

Shaposhnikov, Nickolai; Titarchuk, Lev

2006-01-01

We present timing and spectral analysis of approx. 2.2 Ms of Rossi X-ray Time Explorer (RXTE) archival data from Cyg X-1. Using the generic Comptonization model we reveal that the spectrum of Cyg X-1 consists of three components: a thermal seed photon spectrum, a Comptonized part of the seed photon spectrum and the iron line. We find a strong correlation between 0.1-20 Hz frequencies of quasiperiodic oscillations (QPOs) and the spectral power-law index. Presence of two spectral phases (states) are clearly seen in the data when the spectral indices saturate at low and high values of QPO frequencies. This saturation effect was discovered earlier in a number of black hole candidate (BHC) sources and now we strongly confirm this phenomenon in Cyg X-1. In the soft state this index- QPO frequency correlation shows a saturation of the photon index Gamma approx. 2.1 at high values of the low frequency upsilon(sub L). The saturation level of Gamma approx. 2.1 is the lowest value found yet in BHCs. The bolometric luminosity does not show clear correlation with the index. We also show that Fe K(sub alpha) emission line strength (equivalent width, EW) correlates with the QPO frequency. EW increases from 200 eV in the low/hard state to 1.5 keV in the high/soft state. The revealed observational correlations allow us to propose a scenario for the spectral transition and iron line formation which occur in BHC sources. We also present the spectral state (the power-law index) evolution for eight years of Cyg X-1 observations by RXTE.

What can be found in scalp EEG spectrum beyond common frequency bands. EEG-fMRI study

NASA Astrophysics Data System (ADS)

Marecek, R.; Lamos, M.; Mikl, M.; Barton, M.; Fajkus, J.; I, Rektor; Brazdil, M.

2016-08-01

Objective. The scalp EEG spectrum is a frequently used marker of neural activity. Commonly, the preprocessing of EEG utilizes constraints, e.g. dealing with a predefined subset of electrodes or a predefined frequency band of interest. Such treatment of the EEG spectrum neglects the fact that particular neural processes may be reflected in several frequency bands and/or several electrodes concurrently, and can overlook the complexity of the structure of the EEG spectrum. Approach. We showed that the EEG spectrum structure can be described by parallel factor analysis (PARAFAC), a method which blindly uncovers the spatial-temporal-spectral patterns of EEG. We used an algorithm based on variational Bayesian statistics to reveal nine patterns from the EEG of 38 healthy subjects, acquired during a semantic decision task. The patterns reflected neural activity synchronized across theta, alpha, beta and gamma bands and spread over many electrodes, as well as various EEG artifacts. Main results. Specifically, one of the patterns showed significant correlation with the stimuli timing. The correlation was higher when compared to commonly used models of neural activity (power fluctuations in distinct frequency band averaged across a subset of electrodes) and we found significantly correlated hemodynamic fluctuations in simultaneously acquired fMRI data in regions known to be involved in speech processing. Further, we show that the pattern also occurs in EEG data which were acquired outside the MR machine. Two other patterns reflected brain rhythms linked to the attentional and basal ganglia large scale networks. The other patterns were related to various EEG artifacts. Significance. These results show that PARAFAC blindly identifies neural activity in the EEG spectrum and that it naturally handles the correlations among frequency bands and electrodes. We conclude that PARAFAC seems to be a powerful tool for analysis of the EEG spectrum and might bring novel insight to the relationships between EEG activity and brain hemodynamics.

Atmospheric convective velocities and the Fourier phase spectrum

NASA Technical Reports Server (NTRS)

Cliff, W. C.

1974-01-01

The relationship between convective velocity and the Fourier phase spectrum of the cross correlation is developed. By examining the convective velocity as a function of frequency, one may determine if Taylor's conversion from time statistics to space statistics is valid. It is felt that the high shear regions of the atmospheric boundary layer need to be explored to determine the validity of the use of Taylor's hypothesis for this region.

Femtosecond time-domain observation of atmospheric absorption in the near-infrared spectrum

NASA Astrophysics Data System (ADS)

Hammond, T. J.; Monchocé, Sylvain; Zhang, Chunmei; Brown, Graham G.; Corkum, P. B.; Villeneuve, D. M.

2016-12-01

As light propagates through a medium, absorption caused by electronic or rovibrational transitions is evident in the transmitted spectrum. The incident electromagnetic field polarizes the medium and the absorption is due to the imaginary part of the linear susceptibility. In the time domain, the field establishes a coherence in the medium that radiates out of phase with the initial field. This coherence can persist for tens of picoseconds in atmospheric molecules such as H2O . We propagate a few-cycle laser pulse centered at 1.8 μ m through the atmosphere and measure the long-lasting molecular coherence in the time domain by high-order harmonic cross correlation. The measured optical free-induction decay of the pulse is compared with a calculation based on the calculated rovibrational spectrum of H2O absorption.

Multifractal detrended cross-correlation analysis on gold, crude oil and foreign exchange rate time series

NASA Astrophysics Data System (ADS)

Pal, Mayukha; Madhusudana Rao, P.; Manimaran, P.

2014-12-01

We apply the recently developed multifractal detrended cross-correlation analysis method to investigate the cross-correlation behavior and fractal nature between two non-stationary time series. We analyze the daily return price of gold, West Texas Intermediate and Brent crude oil, foreign exchange rate data, over a period of 18 years. The cross correlation has been measured from the Hurst scaling exponents and the singularity spectrum quantitatively. From the results, the existence of multifractal cross-correlation between all of these time series is found. We also found that the cross correlation between gold and oil prices possess uncorrelated behavior and the remaining bivariate time series possess persistent behavior. It was observed for five bivariate series that the cross-correlation exponents are less than the calculated average generalized Hurst exponents (GHE) for q<0 and greater than GHE when q>0 and for one bivariate series the cross-correlation exponent is greater than GHE for all q values.

Time-resolved GRB spectra in the complex radiation of synchrotron and Compton processes

NASA Astrophysics Data System (ADS)

Jiang, Y. G.; Hu, S. M.; Chen, X.; Li, K.; Guo, D. F.; Li, Y. T.; Li, H. Z.; Zhao, Y. Y.; Lin, H. N.; Chang, Z.

2016-03-01

Under the steady-state condition, the spectrum of electrons is investigated by solving the continuity equation under the complex radiation of both the synchrotron and Compton processes. The resulted gamma-ray burst (GRB) spectrum is a broken power law in both the fast and slow cooling phases. On the basis of this electron spectrum, the spectral indices of the Band function in four different phases are presented. In the complex radiation frame, the detail investigation on physical parameters reveals that three models can answer the α ˜ -1 problem, which are the synchrotron plus synchrotron self-Compton in the internal and the external shock models, and the synchrotron plus the external Compton processes in the external shock model. A possible marginal to fast cooling phase transition in GRB 080916C is discussed. The time-resolved spectra in different main pulses of GRB 100724B, GRB 100826A and GRB 130606B are investigated. We found that the flux is proportional to the peak energy in almost all main pulses. A significant (5σ) correlation for Fp ˜ Ep is evident the first main pulse of GRB 100826A, and three marginally significant (3σ) correlations Fp ˜ Ep are found in main pulses of GRB 100826A and GRB 130606B. The correlation between spectral index and Ep at 3 ˜ 4σ level are observed in the first main pulse of GRB 100826A. Such correlations are possible explained in the complex radiation scenario.

Prevalence and Correlates of Screen-Based Media Use among Youths with Autism Spectrum Disorders

PubMed Central

Mazurek, Micah O.; Shattuck, Paul T.; Wagner, Mary; Cooper, Benjamin P.

2012-01-01

Anecdotal reports indicate that individuals with autism spectrum disorders (ASD) are often preoccupied with television, computers, and video games (screen-based media). However, few studies have examined this issue. The current study examined screen-based media use among a large, nationally representative sample of youths participating in the National Longitudinal Transition Study – 2 (NLTS2). The majority of youths with ASD (64.2%) spent most of their free time using non-social media (television, video games), while only 13.2% spent time on social media (email, internet chatting). Compared with other disability groups (speech/language impairment, learning disabilities, intellectual disabilities), rates of non-social media use were higher among the ASD group, and rates of social media use were lower. Demographic and symptom-specific correlates were also examined. PMID:22160370

Application of interferential correlation of spectrum to the detection of atmospheric pollutants

NASA Technical Reports Server (NTRS)

Fortunato, G.

1979-01-01

The general correlation principles for spectra and spectra derivatives are studied by using the Fourier transform of the spectral distribution of energy from a source illuminating a double beam interferometer with transverse splitting by dividing luminance. In this correlation technique, the use of such an interferometer has the advantage of greater luminosity as compared with a slit spectrometer. However, the correlation example indicates that it is necessary to adapt the correlator to the particular case considered, in order to obtain the best gain in the signal to noise ratio. In the case of sulfur dioxide detection, a very simple mounting which could be used in some interesting industrial applications was developed. This mounting can be used each time that the substance to be analyzed has a quasi-periodic absorption spectrum: in particular this is often the case with absorption spectra of gases, and a mounting identical to the one described for sulfur dioxide proved to be effective in the detection of nitrogen oxides.

Spatiotemporal correlation structure of the Earth's surface temperature

NASA Astrophysics Data System (ADS)

Fredriksen, Hege-Beate; Rypdal, Kristoffer; Rypdal, Martin

2015-04-01

We investigate the spatiotemporal temperature variability for several gridded instrumental and climate model data sets. The temporal variability is analysed by estimating the power spectral density and studying the differences between local and global temperatures, land and sea, and among local temperature records at different locations. The spatiotemporal correlation structure is analysed through cross-spectra that allow us to compute frequency-dependent spatial autocorrelation functions (ACFs). Our results are then compared to theoretical spectra and frequency-dependent spatial ACFs derived from a fractional stochastic-diffusive energy balance model (FEBM). From the FEBM we expect both local and global temperatures to have a long-range persistent temporal behaviour, and the spectral exponent (β) is expected to increase by a factor of two when going from local to global scales. Our comparison of the average local spectrum and the global spectrum shows good agreement with this model, although the FEBM has so far only been studied for a pure land planet and a pure ocean planet, respectively, with no seasonal forcing. Hence it cannot capture the substantial variability among the local spectra, in particular between the spectra for land and sea, and for equatorial and non-equatorial temperatures. Both models and observation data show that land temperatures in general have a low persistence, while sea surface temperatures show a higher, and also more variable degree of persistence. Near the equator the spectra deviate from the power-law shape expected from the FEBM. Instead we observe large variability at time scales of a few years due to ENSO, and a flat spectrum at longer time scales, making the spectrum more reminiscent of that of a red noise process. From the frequency-dependent spatial ACFs we observe that the spatial correlation length increases with increasing time scale, which is also consistent with the FEBM. One consequence of this is that longer-lasting structures must also be wider in space. The spatial correlation length is also observed to be longer for land than for sea. The climate model simulations studied are mainly CMIP5 control runs of length 500-1000 yr. On time scales up to several centuries we do not observe that the difference between the local and global spectral exponents vanish. This also follows from the FEBM and shows that the dynamics is spatiotemporal (not just temporal) even on these time scales.

[EMD Time-Frequency Analysis of Raman Spectrum and NIR].

PubMed

Zhao, Xiao-yu; Fang, Yi-ming; Tan, Feng; Tong, Liang; Zhai, Zhe

2016-02-01

This paper analyzes the Raman spectrum and Near Infrared Spectrum (NIR) with time-frequency method. The empirical mode decomposition spectrum becomes intrinsic mode functions, which the proportion calculation reveals the Raman spectral energy is uniform distributed in each component, while the NIR's low order intrinsic mode functions only undertakes fewer primary spectroscopic effective information. Both the real spectrum and numerical experiments show that the empirical mode decomposition (EMD) regard Raman spectrum as the amplitude-modulated signal, which possessed with high frequency adsorption property; and EMD regards NIR as the frequency-modulated signal, which could be preferably realized high frequency narrow-band demodulation during first-order intrinsic mode functions. The first-order intrinsic mode functions Hilbert transform reveals that during the period of empirical mode decomposes Raman spectrum, modal aliasing happened. Through further analysis of corn leaf's NIR in time-frequency domain, after EMD, the first and second orders components of low energy are cut off, and reconstruct spectral signal by using the remaining intrinsic mode functions, the root-mean-square error is 1.001 1, and the correlation coefficient is 0.981 3, both of these two indexes indicated higher accuracy in re-construction; the decomposition trend term indicates the absorbency is ascending along with the decreasing to wave length in the near-infrared light wave band; and the Hilbert transform of characteristic modal component displays, 657 cm⁻¹ is the specific frequency by the corn leaf stress spectrum, which could be regarded as characteristic frequency for identification.

Dynamical manifestations of quantum chaos: correlation hole and bulge

NASA Astrophysics Data System (ADS)

Torres-Herrera, E. J.; Santos, Lea F.

2017-10-01

A main feature of a chaotic quantum system is a rigid spectrum where the levels do not cross. We discuss how the presence of level repulsion in lattice many-body quantum systems can be detected from the analysis of their time evolution instead of their energy spectra. This approach is advantageous to experiments that deal with dynamics, but have limited or no direct access to spectroscopy. Dynamical manifestations of avoided crossings occur at long times. They correspond to a drop, referred to as correlation hole, below the asymptotic value of the survival probability and to a bulge above the saturation point of the von Neumann entanglement entropy and the Shannon information entropy. By contrast, the evolution of these quantities at shorter times reflects the level of delocalization of the initial state, but not necessarily a rigid spectrum. The correlation hole is a general indicator of the integrable-chaos transition in disordered and clean models and as such can be used to detect the transition to the many-body localized phase in disordered interacting systems. This article is part of the themed issue 'Breakdown of ergodicity in quantum systems: from solids to synthetic matter'.

The lunar neutron energy spectrum inferred from the isotope compositions of rare-earth elements and hafnium in Apollo samples

NASA Astrophysics Data System (ADS)

Albalat, Emmanuelle; Blichert-Toft, Janne; Telouk, Philippe; Albarède, Francis

2015-11-01

The isotopic abundances of Sm, Gd, Dy, Er, Yb, and Hf have been measured in nine lunar samples by MC-ICP-MS. The data were corrected for both instrumental mass bias and natural isotope fractionation. We used the data to calculate the total flux and energy spectrum of the neutrons absorbed by the rocks. We write the constitutive equations of the isotopic changes for these elements induced by neutrons and solve the inverse problem by computing local energy averages. Resonant absorption peaks can be used as convenient kernels to define the spectrum of epithermal neutrons. We find that 149Sm and 157Gd anomalies correlate with neutron flux density for E < 0.015 eV (r2 > 0.98) and E ≈ 0.13 eV (r2 > 0.85), while no significant correlation exists between the ratio of these anomalies and the epithermal/thermal flux ratio at any value of energy. Neutron flux density variations can be used to trace the proportions of neutrons scattered out of the samples. The spectrum in the thermal region follows the expected E - 1 / 2 dependence but with 'notches' corresponding to neutron absorption. A major notch at the lowest end of the epithermal neutron spectrum (0.2-0.8 eV) is possibly due to absorption of neutrons by 151Eu, 167Er, and 149Sm. In general, we find a rather good correlation between the neutron flux density at specific energies and the exposure age, which suggests a mean residence time of the samples at the surface of the regolith of 2-300 Ma. Another correlation of epithermal neutrons with sample wt% FeO + TiO2 is consistent with orbital reflectance observations.

Impaired thalamocortical connectivity in autism spectrum disorder: a study of functional and anatomical connectivity.

PubMed

Nair, Aarti; Treiber, Jeffrey M; Shukla, Dinesh K; Shih, Patricia; Müller, Ralph-Axel

2013-06-01

The thalamus plays crucial roles in the development and mature functioning of numerous sensorimotor, cognitive and attentional circuits. Currently limited evidence suggests that autism spectrum disorder may be associated with thalamic abnormalities, potentially related to sociocommunicative and other impairments in this disorder. We used functional connectivity magnetic resonance imaging and diffusion tensor imaging probabilistic tractography to study the functional and anatomical integrity of thalamo-cortical connectivity in children and adolescents with autism spectrum disorder and matched typically developing children. For connectivity with five cortical seeds (prefontal, parieto-occipital, motor, somatosensory and temporal), we found evidence of both anatomical and functional underconnectivity. The only exception was functional connectivity with the temporal lobe, which was increased in the autism spectrum disorders group, especially in the right hemisphere. However, this effect was robust only in partial correlation analyses (partialling out time series from other cortical seeds), whereas findings from total correlation analyses suggest that temporo-thalamic overconnectivity in the autism group was only relative to the underconnectivity found for other cortical seeds. We also found evidence of microstructural compromise within the thalamic motor parcel, associated with compromise in tracts between thalamus and motor cortex, suggesting that the thalamus may play a role in motor abnormalities reported in previous autism studies. More generally, a number of correlations of diffusion tensor imaging and functional connectivity magnetic resonance imaging measures with diagnostic and neuropsychological scores indicate involvement of abnormal thalamocortical connectivity in sociocommunicative and cognitive impairments in autism spectrum disorder.

Essential Limitations of the Standard THz TDS Method for Substance Detection and Identification and a Way of Overcoming Them

PubMed Central

Trofimov, Vyacheslav A.; Varentsova, Svetlana A.

2016-01-01

Low efficiency of the standard THz TDS method of the detection and identification of substances based on a comparison of the spectrum for the signal under investigation with a standard signal spectrum is demonstrated using the physical experiments conducted under real conditions with a thick paper bag as well as with Si-based semiconductors under laboratory conditions. In fact, standard THz spectroscopy leads to false detection of hazardous substances in neutral samples, which do not contain them. This disadvantage of the THz TDS method can be overcome by using time-dependent THz pulse spectrum analysis. For a quality assessment of the standard substance spectral features presence in the signal under analysis, one may use time-dependent integral correlation criteria. PMID:27070617

Essential Limitations of the Standard THz TDS Method for Substance Detection and Identification and a Way of Overcoming Them.

PubMed

Trofimov, Vyacheslav A; Varentsova, Svetlana A

2016-04-08

Low efficiency of the standard THz TDS method of the detection and identification of substances based on a comparison of the spectrum for the signal under investigation with a standard signal spectrum is demonstrated using the physical experiments conducted under real conditions with a thick paper bag as well as with Si-based semiconductors under laboratory conditions. In fact, standard THz spectroscopy leads to false detection of hazardous substances in neutral samples, which do not contain them. This disadvantage of the THz TDS method can be overcome by using time-dependent THz pulse spectrum analysis. For a quality assessment of the standard substance spectral features presence in the signal under analysis, one may use time-dependent integral correlation criteria.

Separability of spatiotemporal spectra of image sequences. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Eckert, Michael P.; Buchsbaum, Gershon; Watson, Andrew B.

1992-01-01

The spatiotemporal power spectrum was calculated of 14 image sequences in order to determine the degree to which the spectra are separable in space and time, and to assess the validity of the commonly used exponential correlation model found in the literature. The spectrum was expanded by a Singular Value Decomposition into a sum of separable terms and an index was defined of spatiotemporal separability as the fraction of the signal energy that can be represented by the first (largest) separable term. All spectra were found to be highly separable with an index of separability above 0.98. The power spectra of the sequences were well fit by a separable model. The power spectrum model corresponds to a product of exponential autocorrelation functions separable in space and time.

[Tobacco quality analysis of producing areas of Yunnan tobacco using near-infrared (NIR) spectrum].

PubMed

Wang, Yi; Ma, Xiang; Wen, Ya-Dong; Yu, Chun-Xia; Wang, Luo-Ping; Zhao, Long-Lian; Li, Jun-Hui

2013-01-01

In the present study, tobacco quality analysis of different producing areas was carried out applying spectrum projection and correlation methods. The group of industrial classification data was near-infrared (NIR) spectrum in 2010 year of middle parts of tobacco plant from Hongta Tobacco (Group) Co., Ltd. Twelve hundred seventy six superior tobacco leaf samples were collected from four producing areas, in which three areas from Yuxi, Chuxiong and Zhaotong, in Yunnan province all belong to tobacco varieties of K326 and one area from Dali belongs to tobacco varieties of Hongda. The conclusion showed that when the samples were divided into two parts by the ratio of 2 : 1 randomly as analysis and verification sets, the verification set corresponded with the analysis set applying spectrum projection because their correlation coefficients by the first and second dimensional projection were all above 0.99. At the same time, The study discussed a method to get the quantitative similarity values of different producing areas samples. The similarity values were instructive in tobacco plant planning, quality management, acquisition of raw materials of tobacco and tobacco leaf blending.

Nonlinear two-dimensional terahertz photon echo and rotational spectroscopy in the gas phase.

PubMed

Lu, Jian; Zhang, Yaqing; Hwang, Harold Y; Ofori-Okai, Benjamin K; Fleischer, Sharly; Nelson, Keith A

2016-10-18

Ultrafast 2D spectroscopy uses correlated multiple light-matter interactions for retrieving dynamic features that may otherwise be hidden under the linear spectrum; its extension to the terahertz regime of the electromagnetic spectrum, where a rich variety of material degrees of freedom reside, remains an experimental challenge. We report a demonstration of ultrafast 2D terahertz spectroscopy of gas-phase molecular rotors at room temperature. Using time-delayed terahertz pulse pairs, we observe photon echoes and other nonlinear signals resulting from molecular dipole orientation induced by multiple terahertz field-dipole interactions. The nonlinear time domain orientation signals are mapped into the frequency domain in 2D rotational spectra that reveal J-state-resolved nonlinear rotational dynamics. The approach enables direct observation of correlated rotational transitions and may reveal rotational coupling and relaxation pathways in the ground electronic and vibrational state.

Constant-time 2D and 3D through-bond correlation NMR spectroscopy of solids under 60 kHz MAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Rongchun; Ramamoorthy, Ayyalusamy, E-mail: ramamoor@umich.edu

2016-01-21

Establishing connectivity and proximity of nuclei is an important step in elucidating the structure and dynamics of molecules in solids using magic angle spinning (MAS) NMR spectroscopy. Although recent studies have successfully demonstrated the feasibility of proton-detected multidimensional solid-state NMR experiments under ultrafast-MAS frequencies and obtaining high-resolution spectral lines of protons, assignment of proton resonances is a major challenge. In this study, we first re-visit and demonstrate the feasibility of 2D constant-time uniform-sign cross-peak correlation (CTUC-COSY) NMR experiment on rigid solids under ultrafast-MAS conditions, where the sensitivity of the experiment is enhanced by the reduced spin-spin relaxation rate and themore » use of low radio-frequency power for heteronuclear decoupling during the evolution intervals of the pulse sequence. In addition, we experimentally demonstrate the performance of a proton-detected pulse sequence to obtain a 3D {sup 1}H/{sup 13}C/{sup 1}H chemical shift correlation spectrum by incorporating an additional cross-polarization period in the CTUC-COSY pulse sequence to enable proton chemical shift evolution and proton detection in the incrementable t{sub 1} and t{sub 3} periods, respectively. In addition to through-space and through-bond {sup 13}C/{sup 1}H and {sup 13}C/{sup 13}C chemical shift correlations, the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment also provides a COSY-type {sup 1}H/{sup 1}H chemical shift correlation spectrum, where only the chemical shifts of those protons, which are bonded to two neighboring carbons, are correlated. By extracting 2D F1/F3 slices ({sup 1}H/{sup 1}H chemical shift correlation spectrum) at different {sup 13}C chemical shift frequencies from the 3D {sup 1}H/{sup 13}C/{sup 1}H spectrum, resonances of proton atoms located close to a specific carbon atom can be identified. Overall, the through-bond and through-space homonuclear/heteronuclear proximities determined from the 3D {sup 1}H/{sup 13}C/{sup 1}H experiment would be useful to study the structure and dynamics of a variety of chemical and biological solids.« less

[Using 2-DCOS to identify the molecular spectrum peaks for the isomer in the multi-component mixture gases Fourier transform infrared analysis].

PubMed

Zhao, An-Xin; Tang, Xiao-Jun; Zhang, Zhong-Hua; Liu, Jun-Hua

2014-10-01

The generalized two-dimensional correlation spectroscopy and Fourier transform infrared were used to identify hydrocarbon isomers in the mixed gases for absorption spectra resolution enhancement. The Fourier transform infrared spectrum of n-butane and iso-butane and the two-dimensional correlation infrared spectrum of concentration perturbation were used for analysis as an example. The all band and the main absorption peak wavelengths of Fourier transform infrared spectrum for single component gas showed that the spectra are similar, and if they were mixed together, absorption peaks overlap and peak is difficult to identify. The synchronous and asynchronous spectrum of two-dimensional correlation spectrum can clearly identify the iso-butane and normal butane and their respective characteristic absorption peak intensity. Iso-butane has strong absorption characteristics spectrum lines at 2,893, 2,954 and 2,893 cm(-1), and n-butane at 2,895 and 2,965 cm(-1). The analysis result in this paper preliminary verified that the two-dimensional infrared correlation spectroscopy can be used for resolution enhancement in Fourier transform infrared spectrum quantitative analysis.

[The relationship between MMR vaccination level and the number of new cases of autism in children].

PubMed

Mrozek-Budzyn, Dorota; Kiełtyka, Agnieszka

2008-01-01

The MMR vaccination coverage in Malopolskie voivodeship improved rapidly and finally reached a high level during last years. The number of new cases of autism spectrum disorders in children during that time revealed a slightly rising but not significant trend, while the number of childhood autism were stable. Ecological study showed no correlation between MMR vaccination and an increased risk of childhood autism and autism spectrum disorders in children.

The impact of turbulent renewable energy production on power grid stability and quality

NASA Astrophysics Data System (ADS)

Schmietendorf, Katrin; Peinke, Joachim; Kamps, Oliver

2017-11-01

Feed-in fluctuations induced by renewables are one of the key challenges to the stability and quality of electrical power grids. In particular short-term fluctuations disturb the system on a time scale, on which load balancing does not operate yet and the system is intrinsically governed by self-organized synchronization. Wind and solar power are known to be strongly non-Gaussian with intermittent increment statistics in these time scales. We investigate the impact of short-term wind fluctuations on the basis of a Kuramoto-like power grid model considering stability in terms of desynchronization and frequency and voltage quality aspects. We present a procedure to generate realistic feed-in fluctuations with temporal correlations, Kolmogorov power spectrum and intermittent increments. By comparison to correlated Gaussian noise of the same spectrum and Gaussian white noise, we found out that while the correlations are essential to capture the likelihood of severe outages, the intermittent nature of wind power has significant consequences on power quality: intermittency is directly transferred into frequency and voltage fluctuations yielding a novel type of fluctuations, which is beyond engineering status of knowledge.

Nonlinear Analysis of Surface EMG Time Series of Back Muscles

NASA Astrophysics Data System (ADS)

Dolton, Donald C.; Zurcher, Ulrich; Kaufman, Miron; Sung, Paul

2004-10-01

A nonlinear analysis of surface electromyography time series of subjects with and without low back pain is presented. The mean-square displacement and entropy shows anomalous diffusive behavior on intermediate time range 10 ms < t < 1 s. This behavior implies the presence of correlations in the signal. We discuss the shape of the power spectrum of the signal.

Tool Wear Feature Extraction Based on Hilbert Marginal Spectrum

NASA Astrophysics Data System (ADS)

Guan, Shan; Song, Weijie; Pang, Hongyang

2017-09-01

In the metal cutting process, the signal contains a wealth of tool wear state information. A tool wear signal’s analysis and feature extraction method based on Hilbert marginal spectrum is proposed. Firstly, the tool wear signal was decomposed by empirical mode decomposition algorithm and the intrinsic mode functions including the main information were screened out by the correlation coefficient and the variance contribution rate. Secondly, Hilbert transform was performed on the main intrinsic mode functions. Hilbert time-frequency spectrum and Hilbert marginal spectrum were obtained by Hilbert transform. Finally, Amplitude domain indexes were extracted on the basis of the Hilbert marginal spectrum and they structured recognition feature vector of tool wear state. The research results show that the extracted features can effectively characterize the different wear state of the tool, which provides a basis for monitoring tool wear condition.

Evidence of a truncated spectrum in the angular correlation function of the cosmic microwave background

NASA Astrophysics Data System (ADS)

Melia, F.; López-Corredoira, M.

2018-03-01

Aim. The lack of large-angle correlations in the fluctuations of the cosmic microwave background (CMB) conflicts with predictions of slow-roll inflation. But while probabilities (≲0.24%) for the missing correlations disfavour the conventional picture at ≳3σ, factors not associated with the model itself may be contributing to the tension. Here we aim to show that the absence of large-angle correlations is best explained with the introduction of a non-zero minimum wave number kmin for the fluctuation power spectrum P(k). Methods: We assumed that quantum fluctuations were generated in the early Universe with a well-defined power spectrum P(k), although with a cut-off kmin ≠ 0. We then re-calculated the angular correlation function of the CMB and compared it with Planck observations. Results: The Planck 2013 data rule out a zero kmin at a confidence level exceeding 8σ. Whereas purely slow-roll inflation would have stretched all fluctuations beyond the horizon, producing a P(k) with kmin = 0 - and therefore strong correlations at all angles - a kmin ≠ 0 would signal the presence of a maximum wavelength at the time (tdec) of decoupling. This argues against the basic inflationary paradigm, and perhaps even suggests non-inflationary alternatives, for the origin and growth of perturbations in the early Universe. In at least one competing cosmology, the Rh = ct universe, the inferred kmin corresponds to the gravitational radius at tdec.

Experimental quantification of nonlinear time scales in inertial wave rotating turbulence

NASA Astrophysics Data System (ADS)

Yarom, Ehud; Salhov, Alon; Sharon, Eran

2017-12-01

We study nonlinearities of inertial waves in rotating turbulence. At small Rossby numbers the kinetic energy in the system is contained in helical inertial waves with time dependence amplitudes. In this regime the amplitude variations time scales are slow compared to wave periods, and the spectrum is concentrated along the dispersion relation of the waves. A nonlinear time scale was extracted from the width of the spectrum, which reflects the intensity of nonlinear wave interactions. This nonlinear time scale is found to be proportional to (U.k ) -1, where k is the wave vector and U is the root-mean-square horizontal velocity, which is dominated by large scales. This correlation, which indicates the existence of turbulence in which inertial waves undergo weak nonlinear interactions, persists only for small Rossby numbers.

Inferring Weighted Directed Association Network from Multivariate Time Series with a Synthetic Method of Partial Symbolic Transfer Entropy Spectrum and Granger Causality

PubMed Central

Hu, Yanzhu; Ai, Xinbo

2016-01-01

Complex network methodology is very useful for complex system explorer. However, the relationships among variables in complex system are usually not clear. Therefore, inferring association networks among variables from their observed data has been a popular research topic. We propose a synthetic method, named small-shuffle partial symbolic transfer entropy spectrum (SSPSTES), for inferring association network from multivariate time series. The method synthesizes surrogate data, partial symbolic transfer entropy (PSTE) and Granger causality. A proper threshold selection is crucial for common correlation identification methods and it is not easy for users. The proposed method can not only identify the strong correlation without selecting a threshold but also has the ability of correlation quantification, direction identification and temporal relation identification. The method can be divided into three layers, i.e. data layer, model layer and network layer. In the model layer, the method identifies all the possible pair-wise correlation. In the network layer, we introduce a filter algorithm to remove the indirect weak correlation and retain strong correlation. Finally, we build a weighted adjacency matrix, the value of each entry representing the correlation level between pair-wise variables, and then get the weighted directed association network. Two numerical simulated data from linear system and nonlinear system are illustrated to show the steps and performance of the proposed approach. The ability of the proposed method is approved by an application finally. PMID:27832153

Time-Distance Helioseismology

NASA Technical Reports Server (NTRS)

Duvall, Thomas L., Jr.

2010-01-01

Time-distance helioseismology is a method of ambient noise imaging using the solar oscillations. The basic realization that led to time-distance helioseismology was that the temporal cross correlation of the signals at two 'surface' (or photospheric) locations should show a feature at the time lag corresponding to the subsurface travel time between the locations. The temporal cross correlation, as a function of the location separation, is the Fourier transform of the spatio-temporal power spectrum of the solar oscillations, a commonly used function in helioseismology. It is therefore likely the characteristic ridge structure of the correlation function had been seen before without appreciation of its significance. Travel times are measured from the cross correlations. The times are sensitive to a number of important subsurface solar phenomena. These include sound speed variations, flows, and magnetic fields. There has been much interesting progress in the 17 years since the first paper on this subject (Duvall et al., Nature, 1993, 362, 430-432). This progress will be reviewed in this paper.

Halo Pressure Profile through the Skew Cross-power Spectrum of the Sunyaev-Zel’dovich Effect and CMB Lensing in Planck

NASA Astrophysics Data System (ADS)

Timmons, Nicholas; Cooray, Asantha; Feng, Chang; Keating, Brian

2017-11-01

We measure the cosmic microwave background (CMB) skewness power spectrum in Planck, using frequency maps of the HFI instrument and the Sunyaev-Zel’dovich (SZ) component map. The two-to-one skewness power spectrum measures the cross-correlation between CMB lensing and the thermal SZ effect. We also directly measure the same cross-correlation using the Planck CMB lensing map and the SZ map and compare it to the cross-correlation derived from the skewness power spectrum. We model fit the SZ power spectrum and CMB lensing-SZ cross-power spectrum via the skewness power spectrum to constrain the gas pressure profile of dark matter halos. The gas pressure profile is compared to existing measurements in the literature including a direct estimate based on the stacking of SZ clusters in Planck.

An Effective Method for Substance Detection Using the Broad Spectrum THz Signal: A “Terahertz Nose”

PubMed Central

Trofimov, Vyacheslav A.; Varentsova, Svetlana A.

2015-01-01

We propose an effective method for the detection and identification of dangerous substances by using the broadband THz pulse. This pulse excites, for example, many vibrational or rotational energy levels of molecules simultaneously. By analyzing the time-dependent spectrum of the THz pulse transmitted through or reflected from a substance, we follow the average response spectrum dynamics. Comparing the absorption and emission spectrum dynamics of a substance under analysis with the corresponding data for a standard substance, one can detect and identify the substance under real conditions taking into account the influence of packing material, water vapor and substance surface. For quality assessment of the standard substance detection in the signal under analysis, we propose time-dependent integral correlation criteria. Restrictions of usually used detection and identification methods, based on a comparison between the absorption frequencies of a substance under analysis and a standard substance, are demonstrated using a physical experiment with paper napkins. PMID:26020281

Speech Spectrum's Correlation with Speakers' Eysenck Personality Traits

PubMed Central

Hu, Chao; Wang, Qiandong; Short, Lindsey A.; Fu, Genyue

2012-01-01

The current study explored the correlation between speakers' Eysenck personality traits and speech spectrum parameters. Forty-six subjects completed the Eysenck Personality Questionnaire. They were instructed to verbally answer the questions shown on a computer screen and their responses were recorded by the computer. Spectrum parameters of /sh/ and /i/ were analyzed by Praat voice software. Formant frequencies of the consonant /sh/ in lying responses were significantly lower than that in truthful responses, whereas no difference existed on the vowel /i/ speech spectrum. The second formant bandwidth of the consonant /sh/ speech spectrum was significantly correlated with the personality traits of Psychoticism, Extraversion, and Neuroticism, and the correlation differed between truthful and lying responses, whereas the first formant frequency of the vowel /i/ speech spectrum was negatively correlated with Neuroticism in both response types. The results suggest that personality characteristics may be conveyed through the human voice, although the extent to which these effects are due to physiological differences in the organs associated with speech or to a general Pygmalion effect is yet unknown. PMID:22439014

Classification of Acousto-Optic Correlation Signatures of Spread Spectrum Signals Using Artificial Neural Networks

DTIC Science & Technology

1989-12-01

Ohio ’aPw iorlipuab muo i 0I2, AFIT/GE/ENG/89D-10 CLASSIFICATION OF ACOUSTO - OPTIC CORRELATION SIGNATURES OF SPREAD SPECTRUM SIGNALS USING ARTIFICIAL...ENG/89D- 10 CLASSIFICATION OF ACOUSTO - OPTIC CORRELATION SIGNATURES OF SPREAD SPECTRUM SIGNALS USING ARTIFICIAL NEURAL NETWORKS THESIS John W. DeBerry...Captain, USAF AFIT/GE/ENG/89D- 10 Approved for public release; distribution unlimited. AFIT/GE/ENG/89D-10 CLASSIFICATION OF ACOUSTO - OPTIC CORRELATION

Effect of coulomb correlations on luminescence and absorption in compensated semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogoslovskiy, N. A., E-mail: nikitabogoslovskiy@gmail.com; Petrov, P. V.; Ivánov, Yu. L.

2016-07-15

The spectra of donor–acceptor light absorption and luminescence in lightly doped and lightly compensated semiconductors are calculated. In the photoluminescence calculation, two limiting cases of long and short carrier lifetimes relative to the carrier-energy relaxation time are considered. It is shown that, at long lifetimes, the photoluminescence spectrum is significantly shifted toward longer wavelengths due to the relaxation of minority charge carriers. At intermediate lifetimes, the photoluminescence spectrum consists of two peaks, which is in good agreement with the experimental data.

The Pauli Objection

NASA Astrophysics Data System (ADS)

Leon, Juan; Maccone, Lorenzo

2017-12-01

Schrödinger's equation says that the Hamiltonian is the generator of time translations. This seems to imply that any reasonable definition of time operator must be conjugate to the Hamiltonian. Then both time and energy must have the same spectrum since conjugate operators are unitarily equivalent. Clearly this is not always true: normal Hamiltonians have lower bounded spectrum and often only have discrete eigenvalues, whereas we typically desire that time can take any real value. Pauli concluded that constructing a general a time operator is impossible (although clearly it can be done in specific cases). Here we show how the Pauli argument fails when one uses an external system (a "clock") to track time, so that time arises as correlations between the system and the clock (conditional probability amplitudes framework). In this case, the time operator is conjugate to the clock Hamiltonian and not to the system Hamiltonian, but its eigenvalues still satisfy the Schrödinger equation for arbitrary system Hamiltonians.

Phases of New Physics in the BAO Spectrum

NASA Astrophysics Data System (ADS)

Baumann, Daniel; Green, Daniel; Zaldarriaga, Matias

2017-11-01

We show that the phase of the spectrum of baryon acoustic oscillations (BAO) is immune to the effects of nonlinear evolution. This suggests that any new physics that contributes to the initial phase of the BAO spectrum, such as extra light species in the early universe, can be extracted reliably at late times. We provide three arguments in support of our claim: first, we point out that a phase shift of the BAO spectrum maps to a characteristic sign change in the real space correlation function and that this feature cannot be generated or modified by nonlinear dynamics. Second, we confirm this intuition through an explicit computation, valid to all orders in cosmological perturbation theory. Finally, we provide a nonperturbative argument using general analytic properties of the linear response to the initial oscillations. Our result motivates measuring the phase of the BAO spectrum as a robust probe of new physics.

Halo Pressure Profile through the Skew Cross-power Spectrum of the Sunyaev–Zel’dovich Effect and CMB Lensing in Planck

DOE Office of Scientific and Technical Information (OSTI.GOV)

Timmons, Nicholas; Cooray, Asantha; Feng, Chang

2017-11-01

We measure the cosmic microwave background (CMB) skewness power spectrum in Planck , using frequency maps of the HFI instrument and the Sunyaev–Zel’dovich (SZ) component map. The two-to-one skewness power spectrum measures the cross-correlation between CMB lensing and the thermal SZ effect. We also directly measure the same cross-correlation using the Planck CMB lensing map and the SZ map and compare it to the cross-correlation derived from the skewness power spectrum. We model fit the SZ power spectrum and CMB lensing–SZ cross-power spectrum via the skewness power spectrum to constrain the gas pressure profile of dark matter halos. The gasmore » pressure profile is compared to existing measurements in the literature including a direct estimate based on the stacking of SZ clusters in Planck .« less

Quiet-Time Suprathermal (˜0.1 - 200 keV) Electrons in the Solar Wind

NASA Astrophysics Data System (ADS)

Wang, Linghua; Yang, Liu; Tao, Jiawei; Zong, Qiugang; Li, Gang; Wimmer-Schweingruber, Robert; He, Jiansen; Tu, Chuanyi; Bale, Stuart

2017-04-01

We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-200 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. The observed energy spectrum of both (beaming) strahl and (isotropic) halo electrons at ˜0.1-1.5 keV generally fits to a Kappa distribution function with an index κ and effective temperature Teff, while the observed energy spectrum of nearly isotropic superhalo electrons at ˜20-200 keV generally fits to a power-law function, J ˜ E-β. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl density and halo density. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. For the superhalo population, the spectral index β ranges from ˜1.6 to ˜3.7 and the integrated density nsup ranges from 10-8 cm-3 to 10-5 cm-3, with no clear association with the sunspot number. In solar cycle 23 (24), the distribution of β has a broad maximum between 2.4 and 2.8 (2.0 and 2.4). All the strahl, halo and superhalo populations show no obvious correlation with the solar wind core population. These results reflect the nature of the generation of solar wind suprathermal electrons.

Time-frequency wavelet analysis of the interrelationship between the global macro assets and the fear indexes

NASA Astrophysics Data System (ADS)

Abid, Fathi; Kaffel, Bilel

2018-01-01

Understanding the interrelationships of the global macro assets is crucial for global macro investing. This paper investigates the local variance and the interconnection between the stock, gold, oil, Forex and the implied volatility markets in the time/frequency domains using the wavelet methodology, including the wavelet power spectrum, the wavelet squared coherence and phase difference, the wavelet multiple correlation and cross-correlation. The univariate analysis reveals that, in some crisis periods, underlying asset markets present the same pattern in terms of the wavelet power spectrum indicating high volatility for the medium scale, and that for the other market stress periods, volatility behaves differently. Moreover, unlike the underlying asset markets, the implied volatility markets are characterized by high power regions across the entire period, even in the absence of economic events. Bivariate results show a bidirectional relationship between the underlying assets and their corresponding implied volatility indexes, and a steady co-movement between the stock index and its corresponding fear index. Multiple correlation analysis indicates a strong correlation between markets at high scales with evidence of a nearly perfect integration for a period longer than a year. In addition, the hedging strategies based on the volatility index lead to an increase in portfolio correlation. On the other hand, the results from multiple cross-correlations reveal that the lead-lag effect starts from the medium scale and that the VIX (stock market volatility index) index is the potential leader or follower of the other markets.

Using time reversal to detect entanglement and spreading of quantum information

NASA Astrophysics Data System (ADS)

Gaerttner, Martin

2017-04-01

Characterizing and understanding the states of interacting quantum systems and their non-equilibrium dynamics is the goal of quantum simulation. For this it is crucial to find experimentally feasible means for quantifying how entanglement and correlation build up and spread. The ability of analog quantum simulators to reverse the unitary dynamics of quantum many-body systems provides new tools in this quest. One such tool is the multiple-quantum coherence (MQC) spectrum previously used in NMR spectroscopy which can now be studied in so far inaccessible parameter regimes near zero temperature in highly controllable environments. I present recent progress in relating the MQC spectrum to established entanglement witnesses such as quantum Fisher information. Recognizing the MQC as out-of-time-order correlation functions, which quantify the spreading, or scrambling, of quantum information, allows us to establish a connection between these quantities and multi-partite entanglement. I will show recent experimental results obtained with a trapped ion quantum simulator and a spinor BEC illustrating the power of time reversal protocols. Supported by: JILA-NSF-PFC-1125844, NSF-PHY-1521080, ARO, AFOSR, AFOSR-MURI, DARPA, NIST.

Time-Based and Event-Based Prospective Memory in Autism Spectrum Disorder: The Roles of Executive Function and Theory of Mind, and Time-Estimation

ERIC Educational Resources Information Center

Williams, David; Boucher, Jill; Lind, Sophie; Jarrold, Christopher

2013-01-01

Prospective memory (remembering to carry out an action in the future) has been studied relatively little in ASD. We explored time-based (carry out an action at a pre-specified time) and event-based (carry out an action upon the occurrence of a pre-specified event) prospective memory, as well as possible cognitive correlates, among 21…

Helical modes generate antimagnetic rotational spectra in nuclei

NASA Astrophysics Data System (ADS)

Malik, Sham S.

2018-03-01

A systematic analysis of the antimagnetic rotation band using r -helicity formalism is carried out for the first time. The observed octupole correlation in a nucleus is likely to play a role in establishing the antimagnetic spectrum. Such octupole correlations are explained within the helical orbits. In a rotating field, two identical fermions (generally protons) with paired spins generate these helical orbits in such a way that its positive (i.e., up) spin along the axis of quantization refers to one helicity (right-handedness) while negative (down) spin along the same quantization-axis decides another helicity (left-handedness). Since the helicity remains invariant under rotation, therefore, the quantum state of a fermion is represented by definite angular momentum and helicity. These helicity represented states support a pear-shaped structure of a rotating system having z axis as the symmetry axis. A combined operation of parity, time-reversal, and signature symmetries ensures an absence of one of the signature partner band from the observed antimagnetic spectrum. This formalism has also been tested for the recently observed negative parity Δ I =2 antimagnetic spectrum in odd-A 101Pd nucleus and explains nicely its energy spectrum as well as the B (E 2 ) values. Further, this formalism is found to be fully consistent with twin-shears mechanism popularly known for such type of rotational bands. It also provides significant clue for extending these experiments in various mass regions spread over the nuclear chart.

Spread spectrum communication link using surface wave devices

NASA Technical Reports Server (NTRS)

Hunsinger, B. J.; Fugit, B. B.

1971-01-01

A fast lock-up, 8-MHz bandwidth 8,000 bit per second data rate spread spectrum communication link breadboard is described that is implemented using surface wave devices as the primary signal generators and signal processing elements. It uses surface wave tapped delay lines in the transmitter to generate the signals and in the receiver to detect them. The breadboard provides a measured processing gain for Gaussian noise of 31.5 dB which is within one dB of the theoretical optimum. This development demonstrates that spread spectrum receivers implemented with surface wave devices have sensitivities and complexities comparable to those of serial correlation receivers, but synchronization search times which are two to three orders of magnitude smaller.

HSQC-1,n-ADEQUATE: a new approach to long-range 13C-13C correlation by covariance processing.

PubMed

Martin, Gary E; Hilton, Bruce D; Willcott, M Robert; Blinov, Kirill A

2011-10-01

Long-range, two-dimensional heteronuclear shift correlation NMR methods play a pivotal role in the assembly of novel molecular structures. The well-established GHMBC method is a high-sensitivity mainstay technique, affording connectivity information via (n)J(CH) coupling pathways. Unfortunately, there is no simple way of determining the value of n and hence no way of differentiating two-bond from three- and occasionally four-bond correlations. Three-bond correlations, however, generally predominate. Recent work has shown that the unsymmetrical indirect covariance or generalized indirect covariance processing of multiplicity edited GHSQC and 1,1-ADEQUATE spectra provides high-sensitivity access to a (13)C-(13) C connectivity map in the form of an HSQC-1,1-ADEQUATE spectrum. Covariance processing of these data allows the 1,1-ADEQUATE connectivity information to be exploited with the inherent sensitivity of the GHSQC spectrum rather than the intrinsically lower sensitivity of the 1,1-ADEQUATE spectrum itself. Data acquisition times and/or sample size can be substantially reduced when covariance processing is to be employed. In an extension of that work, 1,n-ADEQUATE spectra can likewise be subjected to covariance processing to afford high-sensitivity access to the equivalent of (4)J(CH) GHMBC connectivity information. The method is illustrated using strychnine as a model compound. Copyright © 2011 John Wiley & Sons, Ltd.

Internal Wave Spectrum of Lake Baikal

NASA Astrophysics Data System (ADS)

Tsimitri, C.; Schmid, M.; Wuest, A.

2013-05-01

Lake Baikal is the most voluminous and deepest (over 1.6 Km) fresh water body on earth holding 80% of the world's fresh water supplies. The lake supports a remarkable biodiversity with a major deep-water fauna composed almost entirely of endemic species. Due to the lake's great depth only the top 250 m are experiencing the direct effects of the wind. The deeper part of the lake is barely stratified and has a constant temperature all year round. A distinct peak is observed in the temperature Fourier spectrum around the inertial frequency almost at all times and at all depths. Here we investigate the particularities of the internal wave spectrum using the wavelet transform. We focus on the inertial frequency band and study the propagation through time and depth. Our goal is to evaluate the importance of the internal oscillations to the mixing and to correlate them to external forcing.

Computational analysis of kidney scintigrams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vrincianu, D.; Puscasu, E.; Creanga, D.

The scintigraphic investigation of normal and pathological kidneys was carried out using specialized gamma-camera device from nuclear medicine hospital department. Technetium 90m isotope with gamma radiation emission, coupled with vector molecules for kidney tissues was introduced into the subject body, its dynamics being recorded as data source for kidney clearance capacity. Two representative data series were investigated, corresponding to healthy and pathological organs respectively. The semi-quantitative tests applied for the comparison of the two distinct medical situations were: the shape of probability distribution histogram, the power spectrum, the auto-correlation function and the Lyapunov exponent. While power spectrum led to similarmore » results in both cases, significant differences were revealed by means of distribution probability, Lyapunov exponent and correlation time, recommending these numerical tests as possible complementary tools in clinical diagnosis.« less

Dynamical manifestations of quantum chaos

NASA Astrophysics Data System (ADS)

Torres Herrera, Eduardo Jonathan; Santos, Lea

2017-04-01

A main feature of a chaotic quantum system is a rigid spectrum, where the levels do not cross. Dynamical quantities, such as the von Neumann entanglement entropy, Shannon information entropy, and out-of-time correlators can differentiate the ergodic from the nonergodic phase in disordered interacting systems, but not level repulsion from level crossing in the delocalized phase of disordered and clean models. This is in contrast with the long-time evolution of the survival probability of the initial state. The onset of correlated energy levels is manifested by a drop, referred to as correlation hole, below the asymptotic value of the survival probability. The correlation hole is an unambiguous indicator of the presence of level repulsion. EJTH is grateful to VIEP, BUAP for financial support through the VIEP projects program.

Does the finite size of the proto-neutron star preclude supernova neutrino flavor scintillation due to turbulence?

DOE PAGES

Kneller, James P.; Mauney, Alex W.

2013-08-23

Here, the transition probabilities describing the evolution of a neutrino with a given energy along some ray through a turbulent supernova profile are random variates unique to each ray. If the proto-neutron-star source of the neutrinos were a point, then one might expect the evolution of the turbulence would cause the flavor composition of the neutrinos to vary in time i.e. the flavor would scintillate. But in reality the proto-neutron star is not a point source—it has a size of order ˜10km, so the neutrinos emitted from different points at the source will each have seen different turbulence. The finitemore » source size will reduce the correlation of the flavor transition probabilities along different trajectories and reduce the magnitude of the flavor scintillation. To determine whether the finite size of the proto-neutron star will preclude flavor scintillation, we calculate the correlation of the neutrino flavor transition probabilities through turbulent supernova profiles as a function of the separation δx between the emission points. The correlation will depend upon the power spectrum used for the turbulence, and we consider two cases: when the power spectrum is isotropic, and the more realistic case of a power spectrum which is anisotropic on large scales and isotropic on small. Although it is dependent on a number of uncalibrated parameters, we show the supernova neutrino source is not of sufficient size to significantly blur flavor scintillation in all mixing channels when using an isotropic spectrum, and this same result holds when using an anisotropic spectrum, except when we greatly reduce the similarity of the turbulence along parallel trajectories separated by ˜10km or less.« less

MATERNAL ALCOHOL CONSUMPTION PRODUCING FETAL ALCOHOL SPECTRUM DISORDERS (FASD): QUANTITY, FREQUENCY, AND TIMING OF DRINKING

PubMed Central

May, Philip A.; Blankenship, Jason; Marais, Anna-Susan; Gossage, J. Phillip; Kalberg, Wendy O.; Joubert, Belinda; Cloete, Marise; Barnard, Ronel; De Vries, Marlene; Hasken, Julie; Robinson, Luther K.; Adnams, Colleen M.; Buckley, David; Manning, Melanie; Parry, Charles; Hoyme, H. Eugene; Tabachnick, Barbara; Seedat, Soraya

2013-01-01

Background Concise, accurate measures of maternal prenatal alcohol use are needed to better understand fetal alcohol spectrum disorders (FASD). Methods Measures of drinking by mothers of children with specific FASD diagnoses and mothers of randomly-selected controls are compared and also correlated with physical and cognitive/behavioral outcomes. Results Measures of maternal alcohol use can differentiate maternal drinking associated with FASD from that of controls and some from mothers of alcohol-exposed normals. Six variables that combine quantity and frequency concepts distinguish mothers of FASD children from normal controls. Alcohol use variables, when applied to each trimester and three months prior to pregnancy, provide insight on critical timing of exposure as well. Measures of drinking, especially bingeing, correlate significantly with increased child dysmorphology and negative cognitive/behavioral outcomes in children, especially low non-verbal IQ, poor attention, and behavioral problems. Logistic regression links (p<.001) first trimester drinking (vs. no drinking) with FASD, elevating FASD likelihood 12 times; first and second trimester drinking increases FASD outcomes 61 times; and drinking in all trimesters 65 times. Conversely, a similar regression (p=.008) indicates that drinking only in the first trimester makes the birth of a child with an FASD 5 times less likely than drinking in all trimesters. Conclusions There is significant variation in alcohol consumption both within and between diagnostic groupings of mothers bearing children diagnosed within the FASD continuum. Drinking measures are empirically identified and correlated with specific child outcomes. Alcohol use, especially heavy use, should be avoided throughout pregnancy. PMID:23932841

Maternal alcohol consumption producing fetal alcohol spectrum disorders (FASD): quantity, frequency, and timing of drinking.

PubMed

May, Philip A; Blankenship, Jason; Marais, Anna-Susan; Gossage, J Phillip; Kalberg, Wendy O; Joubert, Belinda; Cloete, Marise; Barnard, Ronel; De Vries, Marlene; Hasken, Julie; Robinson, Luther K; Adnams, Colleen M; Buckley, David; Manning, Melanie; Parry, Charles D H; Hoyme, H Eugene; Tabachnick, Barbara; Seedat, Soraya

2013-12-01

Concise, accurate measures of maternal prenatal alcohol use are needed to better understand fetal alcohol spectrum disorders (FASD). Measures of drinking by mothers of children with specific FASD diagnoses and mothers of randomly-selected controls are compared and also correlated with physical and cognitive/behavioral outcomes. Measures of maternal alcohol use can differentiate maternal drinking associated with FASD from that of controls and some from mothers of alcohol-exposed normals. Six variables that combine quantity and frequency concepts distinguish mothers of FASD children from normal controls. Alcohol use variables, when applied to each trimester and three months prior to pregnancy, provide insight on critical timing of exposure as well. Measures of drinking, especially bingeing, correlate significantly with increased child dysmorphology and negative cognitive/behavioral outcomes in children, especially low non-verbal IQ, poor attention, and behavioral problems. Logistic regression links (p<.001) first trimester drinking (vs. no drinking) with FASD, elevating FASD likelihood 12 times; first and second trimester drinking increases FASD outcomes 61 times; and drinking in all trimesters 65 times. Conversely, a similar regression (p=.008) indicates that drinking only in the first trimester makes the birth of a child with an FASD 5 times less likely than drinking in all trimesters. There is significant variation in alcohol consumption both within and between diagnostic groupings of mothers bearing children diagnosed within the FASD continuum. Drinking measures are empirically identified and correlated with specific child outcomes. Alcohol use, especially heavy use, should be avoided throughout pregnancy. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Time evolution of surface chlorophyll patterns from cross-spectrum analysis of satellite color images

NASA Technical Reports Server (NTRS)

Denman, Kenneth L.; Abbott, Mark R.

1988-01-01

The rate of decorrelation of surface chlorophyll patterns as a function of the time separation between pairs of images was determined from two sequences of CZCS images of the Pacific Ocean area adjacent to Vancouver Island, Canada; cloud-free subareas were selected that were common to several images separated in time by 1-17 days. Image pairs were subjected to two-dimensional autospectrum and cross-spectrum analysis in an array processor, and squared coherence estimates found for several wave bands were plotted against time separation, in analogy with a time-lagged cross correlation function. It was found that, for wavelengths of 50-150 km, significant coherence was lost after 7-10 days, while for wavelengths of 25-50 km, significant coherence was lost after only 5-7 days. In both cases, offshore regions maintained coherence longer than coastal regions.

Polarization properties of fluorescent BSA protected Au25 nanoclusters.

PubMed

Raut, Sangram; Chib, Rahul; Rich, Ryan; Shumilov, Dmytro; Gryczynski, Zygmunt; Gryczynski, Ignacy

2013-04-21

BSA protected gold nanoclusters (Au25) are attracting a great deal of attention due to their unique spectroscopic properties and possible use in biophysical applications. Although there are reports on synthetic strategies, spectroscopy and applications, little is known about their polarization behavior. In this study, we synthesized the BSA protected Au25 nanoclusters and studied their steady state and time resolved fluorescence properties including polarization behavior in different solvents: glycerol, propylene glycol and water. We demonstrated that the nanocluster absorption spectrum can be separated from the extinction spectrum by subtraction of Rayleigh scattering. The nanocluster absorption spectrum is well approximated by three Gaussian components. By a comparison of the emissions from BSA Au25 clusters and rhodamine B in water, we estimated the quantum yield of nanoclusters to be higher than 0.06. The fluorescence lifetime of BSA Au25 clusters is long and heterogeneous with an average value of 1.84 μs. In glycerol at -20 °C the anisotropy is high, reaching a value of 0.35. However, the excitation anisotropy strongly depends on the excitation wavelengths indicating a significant overlap of the different transition moments. The anisotropy decay in water reveals a correlation time below 0.2 μs. In propylene glycol the measured correlation time is longer and the initial anisotropy depends on the excitation wavelength. BSA Au25 clusters, due to long lifetime and high polarization, can potentially be used in studying large macromolecules such as protein complexes with large molecular weight.

Spectrum-energy Correlations in GRBs: Update, Reliability, and the Long/Short Dichotomy

NASA Astrophysics Data System (ADS)

Zhang, Z. B.; Zhang, C. T.; Zhao, Y. X.; Luo, J. J.; Jiang, L. Y.; Wang, X. L.; Han, X. L.; Terheide, R. K.

2018-05-01

Spectrum-energy correlations of peak energy with total prompt γ-ray emission energies, namely {E}p,i-{E}{iso}, {E}p,i-{E}γ , and {E}p,i-{L}p, had been studied for long gamma-ray bursts (GRBs) previously by many authors. These energy correlations were proposed to measure the universe and classify GRBs as useful probes. However, most of these relations were built by non-Swift bursts. The spectrum-energy correlations of short bursts have not been systematically established yet; in particular, how the newly found GRB170817A matches these energy relations is unknown to date. We will first refresh the three spectrum-energy relations of Swift/BAT and Fermi/GBM long bursts and build the corresponding relations of short bursts. Then, we confirm whether they are commonly available as a discriminator of short and long GRBs. Some potential violators to these relations will be investigated. Combining with the plane of peak energy versus fluence, we select 31 short and 252 long GRBs with well-measured peak energy and redshift to study the issue of GRB classifications connected with the above energy relations statistically. We find that the three energy relations do exist in our new GRB samples and they are marginally consistent with some previous results. We report for the first time that short GRBs hold the three corresponding energy relations having the consistent power-law indices with long GRBs. It is found that these energy relations can be adopted to discriminate GRBs successfully if they are put in the peak energy versus fluence plane. Excitingly, we point out that GRB090510 matches the energy relations of {E}p,i-{E}{iso} and {E}p,i-{L}p, but violates the {E}p,i-{E}γ relation. More excitingly, we find that GRB170817A is an outlier to all the three energy correlations.

Multiple-taper spectral analysis: A stand-alone C-subroutine

NASA Astrophysics Data System (ADS)

Lees, Jonathan M.; Park, Jeffrey

1995-03-01

A simple set of subroutines in ANSI-C are presented for multiple taper spectrum estimation. The multitaper approach provides an optimal spectrum estimate by minimizing spectral leakage while reducing the variance of the estimate by averaging orthogonal eigenspectrum estimates. The orthogonal tapers are Slepian nπ prolate functions used as tapers on the windowed time series. Because the taper functions are orthogonal, combining them to achieve an average spectrum does not introduce spurious correlations as standard smoothed single-taper estimates do. Furthermore, estimates of the degrees of freedom and F-test values at each frequency provide diagnostics for determining levels of confidence in narrow band (single frequency) periodicities. The program provided is portable and has been tested on both Unix and Macintosh systems.

Jet Aeroacoustics: Noise Generation Mechanism and Prediction

NASA Technical Reports Server (NTRS)

Tam, Christopher

1998-01-01

This report covers the third year research effort of the project. The research work focussed on the fine scale mixing noise of both subsonic and supersonic jets and the effects of nozzle geometry and tabs on subsonic jet noise. In publication 1, a new semi-empirical theory of jet mixing noise from fine scale turbulence is developed. By an analogy to gas kinetic theory, it is shown that the source of noise is related to the time fluctuations of the turbulence kinetic theory. On starting with the Reynolds Averaged Navier-Stokes equations, a formula for the radiated noise is derived. An empirical model of the space-time correlation function of the turbulence kinetic energy is adopted. The form of the model is in good agreement with the space-time two-point velocity correlation function measured by Davies and coworkers. The parameters of the correlation are related to the parameters of the k-epsilon turbulence model. Thus the theory is self-contained. Extensive comparisons between the computed noise spectrum of the theory and experimental measured have been carried out. The parameters include jet Mach number from 0.3 to 2.0 and temperature ratio from 1.0 to 4.8. Excellent agreements are found in the spectrum shape, noise intensity and directivity. It is envisaged that the theory would supercede all semi-empirical and totally empirical jet noise prediction methods in current use.

Human movement stochastic variability leads to diagnostic biomarkers In Autism Spectrum Disorders (ASD)

NASA Astrophysics Data System (ADS)

Wu, Di; Torres, Elizabeth B.; Jose, Jorge V.

2015-03-01

ASD is a spectrum of neurodevelopmental disorders. The high heterogeneity of the symptoms associated with the disorder impedes efficient diagnoses based on human observations. Recent advances with high-resolution MEM wearable sensors enable accurate movement measurements that may escape the naked eye. It calls for objective metrics to extract physiological relevant information from the rapidly accumulating data. In this talk we'll discuss the statistical analysis of movement data continuously collected with high-resolution sensors at 240Hz. We calculated statistical properties of speed fluctuations within the millisecond time range that closely correlate with the subjects' cognitive abilities. We computed the periodicity and synchronicity of the speed fluctuations' from their power spectrum and ensemble averaged two-point cross-correlation function. We built a two-parameter phase space from the temporal statistical analyses of the nearest neighbor fluctuations that provided a quantitative biomarker for ASD and adult normal subjects and further classified ASD severity. We also found age related developmental statistical signatures and potential ASD parental links in our movement dynamical studies. Our results may have direct clinical applications.

Characteristics of autism spectrum disorder in anorexia nervosa: A naturalistic study in an inpatient treatment programme.

PubMed

Tchanturia, Kate; Adamson, James; Leppanen, Jenni; Westwood, Heather

2017-11-01

Previous research has demonstrated links between anorexia nervosa and autism spectrum disorder however, few studies have examined the possible impact of symptoms of autism spectrum disorder on clinical outcomes in anorexia nervosa. The aim of this study was to examine the association between symptoms of autism spectrum disorder and eating disorders, and other psychopathology during the course of inpatient treatment in individuals with anorexia nervosa. Participants with anorexia nervosa (n = 171) completed questionnaires exploring eating disorder psychopathology, symptoms of depression and anxiety, and everyday functioning at both admission and discharge. Characteristics associated with autism spectrum disorder were assessed using the Autism Spectrum Quotient, short version. Autism spectrum disorder symptoms were significantly positively correlated with eating disorder psychopathology, work and social functioning, and symptoms of depression and anxiety, but not with body mass index. Autism Spectrum Quotient, short version scores remained relatively stable from admission to discharge but there was a small, significant reduction in scores. There was no interaction between time and Autism Spectrum Quotient, short version scores on clinical symptom change. In anorexia nervosa, autism spectrum disorder symptoms appear to be associated with a more severe clinical presentation on admission to inpatient care. Autism spectrum disorder symptoms as assessed by self-report measures may be exacerbated by other mental health psychopathology, which warrants further investigation.

Longitudinal patterns of employment and postsecondary education for adults with autism and average-range IQ.

PubMed

Taylor, Julie Lounds; Henninger, Natalie A; Mailick, Marsha R

2015-10-01

This study examined correlates of participation in postsecondary education and employment over 12 years for 73 adults with autism spectrum disorders and average-range IQ whose families were part of a larger, longitudinal study. Correlates included demographic (sex, maternal education, paternal education), behavioral (activities of daily living, maladaptive behaviors, autism symptoms), and family (size of maternal social network; maternal depressive symptoms, anxiety, and pessimism) factors. Although two-thirds of adults with autism spectrum disorder participated in competitive employment/postsecondary education during the study, fewer than 25% maintained these activities over the study period. Behavioral characteristics distinguished those who never had competitive employment/postsecondary education from those who sometimes or consistently participated in these activities. Women were considerably less likely than men to maintain employment/postsecondary education over time. © The Author(s) 2015.

Video Game Access, Parental Rules, and Problem Behavior: A Study of Boys with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Engelhardt, Christopher R.; Mazurek, Micah O.

2014-01-01

Environmental correlates of problem behavior among individuals with autism spectrum disorder remain relatively understudied. The current study examined the contribution of in-room (i.e. bedroom) access to a video game console as one potential correlate of problem behavior among a sample of 169 boys with autism spectrum disorder (ranging from 8 to…

Trampoline Effect: Observations and Modeling

NASA Astrophysics Data System (ADS)

Guyer, R.; Larmat, C. S.; Ulrich, T. J.

2009-12-01

The Iwate-Miyagi earthquake at site IWTH25 (14 June 2008) had large, asymmetric at surface vertical accelerations prompting the sobriquet trampoline effect (Aoi et. al. 2008). In addition the surface acceleration record showed long-short waiting time correlations and vertical-horizontal acceleration correlations. A lumped element model, deduced from the equations of continuum elasticity, is employed to describe the behavior at this site in terms of a surface layer and substrate. Important ingredients in the model are the nonlinear vertical coupling between the surface layer and the substrate and the nonlinear horizontal frictional coupling between the surface layer and the substrate. The model produces results in qualitative accord with observations: acceleration asymmetry, Fourier spectrum, waiting time correlations and vertical acceleration-horizontal acceleration correlations. [We gratefully acknowledge the support of the U. S. Department of Energy through the LANL/LDRD Program for this work].

(abstract) Cross with Your Spectra? Cross-Correlate Instead!

NASA Technical Reports Server (NTRS)

Beer, Reinhard

1994-01-01

The use of cross-correlation for certain types of spectral analysis is discussed. Under certain circumstances, the use of cross-correlation between a real spectrum and either a model or another spectrum can provide a very powerful tool for spectral analysis. The method (and its limitations) will be described with concrete examples using ATMOS data.

From standard alpha-stable Lévy motions to horizontal visibility networks: dependence of multifractal and Laplacian spectrum

NASA Astrophysics Data System (ADS)

Zou, Hai-Long; Yu, Zu-Guo; Anh, Vo; Ma, Yuan-Lin

2018-05-01

In recent years, researchers have proposed several methods to transform time series (such as those of fractional Brownian motion) into complex networks. In this paper, we construct horizontal visibility networks (HVNs) based on the -stable Lévy motion. We aim to study the relations of multifractal and Laplacian spectrum of transformed networks on the parameters and of the -stable Lévy motion. First, we employ the sandbox algorithm to compute the mass exponents and multifractal spectrum to investigate the multifractality of these HVNs. Then we perform least squares fits to find possible relations of the average fractal dimension , the average information dimension and the average correlation dimension against using several methods of model selection. We also investigate possible dependence relations of eigenvalues and energy on , calculated from the Laplacian and normalized Laplacian operators of the constructed HVNs. All of these constructions and estimates will help us to evaluate the validity and usefulness of the mappings between time series and networks, especially between time series of -stable Lévy motions and HVNs.

Multifractal diffusion entropy analysis: Optimal bin width of probability histograms

NASA Astrophysics Data System (ADS)

Jizba, Petr; Korbel, Jan

2014-11-01

In the framework of Multifractal Diffusion Entropy Analysis we propose a method for choosing an optimal bin-width in histograms generated from underlying probability distributions of interest. The method presented uses techniques of Rényi’s entropy and the mean squared error analysis to discuss the conditions under which the error in the multifractal spectrum estimation is minimal. We illustrate the utility of our approach by focusing on a scaling behavior of financial time series. In particular, we analyze the S&P500 stock index as sampled at a daily rate in the time period 1950-2013. In order to demonstrate a strength of the method proposed we compare the multifractal δ-spectrum for various bin-widths and show the robustness of the method, especially for large values of q. For such values, other methods in use, e.g., those based on moment estimation, tend to fail for heavy-tailed data or data with long correlations. Connection between the δ-spectrum and Rényi’s q parameter is also discussed and elucidated on a simple example of multiscale time series.

Smeared spectrum jamming suppression based on generalized S transform and threshold segmentation

NASA Astrophysics Data System (ADS)

Li, Xin; Wang, Chunyang; Tan, Ming; Fu, Xiaolong

2018-04-01

Smeared Spectrum (SMSP) jamming is an effective jamming in countering linear frequency modulation (LFM) radar. According to the time-frequency distribution difference between jamming and echo, a jamming suppression method based on Generalized S transform (GST) and threshold segmentation is proposed. The sub-pulse period is firstly estimated based on auto correlation function firstly. Secondly, the time-frequency image and the related gray scale image are achieved based on GST. Finally, the Tsallis cross entropy is utilized to compute the optimized segmentation threshold, and then the jamming suppression filter is constructed based on the threshold. The simulation results show that the proposed method is of good performance in the suppression of false targets produced by SMSP.

Can observations look back to the beginning of inflation?

NASA Astrophysics Data System (ADS)

Wetterich, C.

2016-03-01

The cosmic microwave background can measure the inflaton potential only if inflation lasts sufficiently long before the time of horizon crossing of observable fluctuations, such that non-linear effects in the time evolution of Green's functions lead to a loss of memory of initial conditions for the ultraviolet tail of the spectrum. Within a derivative expansion of the quantum effective action for an interacting scalar field we discuss the most general solution for the correlation function, including arbitrary pure and mixed quantum states. In this approximation no loss of memory occurs - cosmic microwave observations see the initial spectrum at the beginning of inflation, processed only mildly by the scale-violating effects at horizon crossing induced by the inflaton potential.

New Possibilities of Substance Identification Based on THz Time Domain Spectroscopy Using a Cascade Mechanism of High Energy Level Excitation

PubMed Central

Trofimov, Vyacheslav A.; Varentsova, Svetlana A.; Zakharova, Irina G.; Zagursky, Dmitry Yu.

2017-01-01

Using an experiment with thin paper layers and computer simulation, we demonstrate the principal limitations of standard Time Domain Spectroscopy (TDS) based on using a broadband THz pulse for the detection and identification of a substance placed inside a disordered structure. We demonstrate the spectrum broadening of both transmitted and reflected pulses due to the cascade mechanism of the high energy level excitation considering, for example, a three-energy level medium. The pulse spectrum in the range of high frequencies remains undisturbed in the presence of a disordered structure. To avoid false absorption frequencies detection, we apply the spectral dynamics analysis method (SDA-method) together with certain integral correlation criteria (ICC). PMID:29186849

Direction of an initial saccade depends on radiological expertise

NASA Astrophysics Data System (ADS)

Pietrzyk, Mariusz W.; McEntee, Mark F.; Evanoff, Michael E.; Brennan, Patrick C.; Mello-Thoms, Claudia R.

2014-03-01

Purpose: To evaluate the role of radiographic details in global impression of chest x-ray images viewed by experts in thoracic and non-thoracic domains. Materials and Methods: The study was approved by IRB. Five thoracic and five non-thoracic radiologists participated in two tachistoscopic (one low pass and one with the entire frequency spectrum, each lasting 270 ms) each containing 50 PA chest radiographs with 50% prevalence of pulmonary nodule. Eye movements were monitored in order to evaluate a pre-saccade shift of visual attention, saccade latency, decision time and the time to first fixation on a pulmonary nodule. Results: Thoracic radiologists showed significantly higher pre-saccadic shift of visual attention towards pulmonary nodules once using the full frequency spectrum (p < 0.05). An initial saccade orientation made by these radiologists on full resolution images correlated at significant level with their confidence ranking of pulmonary nodules (ρ = -0.387, p < 0.001). Conclusions: Thoracic radiologists benefited from high spatial frequency appearance during a rapid presentation of chest radiograph by allocating pre-saccade attention towards pulmonary nodules. This behavior correlated with a higher number of correct decisions, followed by higher confidence in the decisions made, and briefer reaction times.

Recent mathematical developments in 2D correlation spectroscopy

NASA Astrophysics Data System (ADS)

Noda, I.

2000-03-01

Recent mathematical developments in the field of 2D correlation spectroscopy, especially those related to the statistical theory, are reported. The notion of correlation phase angle is introduced. The significance of correlation phase angle between dynamic fluctuations of signals measured at two different spectral variables may be linked to more commonly known statistical concepts, such as coherence and correlation coefficient. This treatment provides the direct mathematical connection between the synchronous 2D correlation spectrum with a continuous form of the variance-covariance matrix. Moreover, it gives the background for the formal definition of the disrelation spectrum, which may be used as a heuristic substitution for the asynchronous 2D spectrum. The 2D correlation intensity may be separated into two independent factors representing the normalized extent of signal fluctuation coherence (i.e., correlation coefficient) and the magnitude of spectral intensity changes (i.e., variance). Such separation offers a convenient way to artificially enhance the discriminating power of 2D correlation spectra.

Predictions for measuring the cross power spectrum of the HI 21-cm signal and the Lyman-α forest using OWFA

NASA Astrophysics Data System (ADS)

Sarkar, Anjan Kumar; Bharadwaj, Somnath; Guha Sarkar, Tapomoy

2018-05-01

We have studied the possibility of measuring the cross-correlation of the redshifted HI 21-cm signal and the Lyman-α forest using an upcoming radio-interferometric array OWFA and an spectroscopic observation like SDSS-IV. Our results shows that it is possible to have a 6 σ detection of the cross-correlation signal with OWFA PII using an observing time of 200 hrs each in Np = 25 independent fields-of-view. However, not much can be done beyond this using the cross-correlation signal for zc = 3.35 and B = 30 MHz. Apart from this, we have also envisaged a situation where observations are carried out at zc = 3.05 and 2.55 which lie closer to the peak of the quasar distribution at z = 2.25 and with a larger bandwidth of B = 60 MHz. We see that the SNR of the cross-correlation detection can be significantly enhanced to ~ 17 for zc = 2.55 and B = 60 MHz. It is then possible to measure βT and βF individually with an SNR >= 5 by combining the cross-correlation with the HI 21-cm auto-correlation measurements. We further find that a measurement of the binned cross-correlation power spectrum with SNR >= 5 is also possible in several bins at k <= 0.3 Mpc‑1.

Studies on spectral analysis of randomly sampled signals: Application to laser velocimetry data

NASA Technical Reports Server (NTRS)

Sree, David

1992-01-01

Spectral analysis is very useful in determining the frequency characteristics of many turbulent flows, for example, vortex flows, tail buffeting, and other pulsating flows. It is also used for obtaining turbulence spectra from which the time and length scales associated with the turbulence structure can be estimated. These estimates, in turn, can be helpful for validation of theoretical/numerical flow turbulence models. Laser velocimetry (LV) is being extensively used in the experimental investigation of different types of flows, because of its inherent advantages; nonintrusive probing, high frequency response, no calibration requirements, etc. Typically, the output of an individual realization laser velocimeter is a set of randomly sampled velocity data. Spectral analysis of such data requires special techniques to obtain reliable estimates of correlation and power spectral density functions that describe the flow characteristics. FORTRAN codes for obtaining the autocorrelation and power spectral density estimates using the correlation-based slotting technique were developed. Extensive studies have been conducted on simulated first-order spectrum and sine signals to improve the spectral estimates. A first-order spectrum was chosen because it represents the characteristics of a typical one-dimensional turbulence spectrum. Digital prefiltering techniques, to improve the spectral estimates from randomly sampled data were applied. Studies show that the spectral estimates can be increased up to about five times the mean sampling rate.

Differences in praxis performance and receptive language during fingerspelling between deaf children with and without autism spectrum disorder.

PubMed

Bhat, Anjana N; Srinivasan, Sudha M; Woxholdt, Colleen; Shield, Aaron

2018-04-01

Children with autism spectrum disorder present with a variety of social communication deficits such as atypicalities in social gaze and verbal and non-verbal communication delays as well as perceptuo-motor deficits like motor incoordination and dyspraxia. In this study, we had the unique opportunity to study praxis performance in deaf children with and without autism spectrum disorder in a fingerspelling context using American Sign Language. A total of 11 deaf children with autism spectrum disorder and 11 typically developing deaf children aged between 5 and 14 years completed a fingerspelling task. Children were asked to fingerspell 15 different words shown on an iPad. We coded various praxis errors and fingerspelling time. The deaf children with autism spectrum disorder had greater errors in pace, sequence precision, accuracy, and body part use and also took longer to fingerspell each word. Additionally, the deaf children with autism spectrum disorder had poor receptive language skills and this strongly correlated with their praxis performance and autism severity. These findings extend the evidence for dyspraxia in hearing children with autism spectrum disorder to deaf children with autism spectrum disorder. Poor sign language production in children with autism spectrum disorder may contribute to their poor gestural learning/comprehension and vice versa. Our findings have therapeutic implications for children with autism spectrum disorder when teaching sign language.

Spectral analysis of finite-time correlation matrices near equilibrium phase transitions

NASA Astrophysics Data System (ADS)

Vinayak; Prosen, T.; Buča, B.; Seligman, T. H.

2014-10-01

We study spectral densities for systems on lattices, which, at a phase transition display, power-law spatial correlations. Constructing the spatial correlation matrix we prove that its eigenvalue density shows a power law that can be derived from the spatial correlations. In practice time series are short in the sense that they are either not stationary over long time intervals or not available over long time intervals. Also we usually do not have time series for all variables available. We shall make numerical simulations on a two-dimensional Ising model with the usual Metropolis algorithm as time evolution. Using all spins on a grid with periodic boundary conditions we find a power law, that is, for large grids, compatible with the analytic result. We still find a power law even if we choose a fairly small subset of grid points at random. The exponents of the power laws will be smaller under such circumstances. For very short time series leading to singular correlation matrices we use a recently developed technique to lift the degeneracy at zero in the spectrum and find a significant signature of critical behavior even in this case as compared to high temperature results which tend to those of random matrix models.

X-ray variability of Cygnus X-1 in its soft state

NASA Technical Reports Server (NTRS)

Cui, W.; Zhang, S. N.; Jahoda, K.; Focke, W.; Swank, J.; Heindl, W. A.; Rothschild, R. E.

1997-01-01

Observations from the Rossi X-ray Timing Explorer (RXTE) of Cyg X-1 in the soft state and during the soft to hard transition are examined. The results of this analysis confirm previous conclusions that for this source there is a settling period (following the transition from the hard to soft state during which the low energy spectrum varies significantly, while the high energy portion changes little) during which the source reaches nominal soft state brightness. This behavior can be characterized by a soft low energy spectrum and significant low frequency 1/f noise and white noise on the power density spectrum, which becomes softer upon reaching the true soft state. The low frequency 1/f noise is not observed when Cyg X-1 is in the hard state, and therefore appears to be positively correlated with the disk mass accretion rate. The difference in the observed spectral and timing properties between the hard and soft states is qualitatively consistent with a fluctuating corona model.

Neural Mechanisms of Improvements in Social Motivation after Pivotal Response Treatment: Two Case Studies

ERIC Educational Resources Information Center

Voos, Avery C.; Pelphrey, Kevin A.; Tirrell, Jonathan; Bolling, Danielle Z.; Vander Wyk, Brent; Kaiser, Martha D.; McPartland, James C.; Volkmar, Fred R.; Ventola, Pamela

2013-01-01

Pivotal response treatment (PRT) is an empirically validated behavioral treatment that has widespread positive effects on communication, behavior, and social skills in young children with autism spectrum disorder (ASD). For the first time, functional magnetic resonance imaging was used to identify the neural correlates of successful response to…

Chaotic behavior in the locomotion of Amoeba proteus.

PubMed

Miyoshi, H; Kagawa, Y; Tsuchiya, Y

2001-01-01

The locomotion of Amoeba proteus has been investigated by algorithms evaluating correlation dimension and Lyapunov spectrum developed in the field of nonlinear science. It is presumed by these parameters whether the random behavior of the system is stochastic or deterministic. For the analysis of the nonlinear parameters, n-dimensional time-delayed vectors have been reconstructed from a time series of periphery and area of A. proteus images captured with a charge-coupled-device camera, which characterize its random motion. The correlation dimension analyzed has shown the random motion of A. proteus is subjected only to 3-4 macrovariables, though the system is a complex system composed of many degrees of freedom. Furthermore, the analysis of the Lyapunov spectrum has shown its largest exponent takes positive values. These results indicate the random behavior of A. proteus is chaotic and deterministic motion on an attractor with low dimension. It may be important for the elucidation of the cell locomotion to take account of nonlinear interactions among a small number of dynamics such as the sol-gel transformation, the cytoplasmic streaming, and the relating chemical reaction occurring in the cell.

Simultaneous observation of glutamate, gamma-aminobutyric acid, and glutamine in human brain at 4.7 T using localized two-dimensional constant-time correlation spectroscopy.

PubMed

Watanabe, H; Takaya, N; Mitsumori, F

2008-06-01

Localized two-dimensional constant-time correlation spectroscopy (CT-COSY) was used to resolve glutamate (Glu), gamma-aminobutyric acid (GABA), and glutamine (Gln) in the human brain at 4.7 T. In this method, three-dimensional localization was achieved using three radio frequency pulses of the CT-COSY module for slice selection. As this sequence could decouple JHH along the F1 direction, peak resolution of metabolites was improved even on a magnitude-mode display. In experiments on a phantom containing N-acetylaspartate, creatine, Glu, Gln, and GABA with a constant time delay (Tct) of 110 ms, cross peaks of Glu, Gln, and GABA were obtained on a spectrum processed with standard sine-bell windows, which emphasize sine-dependent signals along the t2 direction. In contrast, diagonal peaks of Glu C4H at 2.35 ppm, GABA C2H at 2.28 ppm, and Gln C4H at 2.44 ppm were resolved on a spectrum processed with Gaussian windows, which emphasize cosine-dependent signals along t2. Human brain spectra were obtained from a 27 mL voxel within the parieto-occipital region using a volume transverse electromagnetic (TEM) coil for both transmission and reception. Tct was 110 ms; the total scan time was 30 min. Diagonal peaks of Glu C4H, GABA C2H, and Gln C4H were also resolved on the spectrum processed with Gaussian windows. These results show that the localized two-dimensional CT-COSY method featuring 1H decoupling along the F1 direction could resolve Glu, GABA, and Gln signals in the human brain. Copyright (c) 2008 John Wiley & Sons, Ltd.

Vibrational Relaxation and Dynamical Transitions in Atactic Polystyrene

NASA Astrophysics Data System (ADS)

Zhao, Hanqing; Park, Yung; Painter, Paul

2009-03-01

Infrared bands and Raman lines recorded in the frequency domain have a counterpart in the time domain in the form of time-correlation functions, which are sensitive to molecular dynamics on the picosecond time scale. This is explored by calculating time correlation functions and their variation with temperature for the conformationally insensitive modes observed near 1601 cm-1 and 1583 cm-1 in the infrared spectrum of atactic polystyrene. The correlation functions were modeled by assuming that there is a fast relaxation process characterized by a single relaxation time that is inhomogeneously broadened by a slower process, also characterized by a single relaxation time. The fundamental mode, near 1583 cm-1, is inhomogeneously broadened, but the relaxation time calculated for this mode is sensitive to temperature as a result of anharmonic coupling to a combination mode. A change in the modulation of the 1583 cm-1 band becomes apparent about 10--20 degrees below the thermally measured Tg. Relaxation times at first increase then decrease and becomes negligible at temperatures near 180 degrees. These results are consistent with theories of the glass transition.

Fractal properties of background noise and target signal enhancement using CSEM data

NASA Astrophysics Data System (ADS)

Benavides, Alfonso; Everett, Mark E.; Pierce, Carl; Nguyen, Cam

2003-09-01

Controlled-source electromagnetic (CSEM) spatial profiles and 2-D conductivity maps were obtained on the Brazos Valley, TX floodplain to study the fractal statistics of geological signals and effects of man-made conductive targets using Geonics EM34, EM31 and EM63. Using target-free areas, a consistent power-law power spectrum (|A(k)| ~ k ^-β) for the profiles was found with β values typical of fractional Brownian motion (fBm). This means that the spatial variation of conductivity does not correspond to Gaussian statistics, where there are spatial correlations at different scales. The presence of targets tends to flatten the power-law power spectrum (PS) at small wavenumbers. Detection and localization of targets can be achieved using short-time Fourier transform (STFT). The presence of targets is enhanced because the signal energy is spread to higher wavenumbers (small scale numbers) in the positions occupied by the targets. In the case of poor spatial sampling or small amount of data, the information available from the power spectrum is not enough to separate spatial correlations from target signatures. Advantages are gained by using the spatial correlations of the fBm in order to reject the background response, and to enhance the signals from highly conductive targets. This approach was tested for the EM31 using a pre-processing step that combines apparent conductivity readings from two perpendicular transmitter-receiver orientations at each station. The response obtained using time-domain CSEM is influence to a lesser degree by geological noise and the target response can be processed to recover target features. The homotopy method is proposed to solve the inverse problem using a set of possible target models and a dynamic library of responses used to optimize the starting model.

Discovery and Monitoring of a New Black Hole Candidate XTE J1752-223 with RXTE: RMS Spectrum Evolution, BH Mass and the Source Distance

NASA Technical Reports Server (NTRS)

Shaposhinikov, Nikolai; Markwardt, Craig; Swank, Jean; Krimm, Hans

2010-01-01

We report on the discovery and monitoring observations of a new galactic black hole candidate XTE J1752-223 by Rossi X-ray Timing Explorer (RXTE). The new source appeared on the X-ray sky on October 21 2009 and was active for almost 8 months. Phenomenologically, the source exhibited the low-hard/highsoft spectral state bi-modality and the variability evolution during the state transition that matches standard behavior expected from a stellar mass black hole binary. We model the energy spectrum throughout the outburst using a generic Comptonization model assuming that part of the input soft radiation in the form of a black body spectrum gets reprocessed in the Comptonizing medium. We follow the evolution of fractional root-mean-square (RMS) variability in the RXTE/PCA energy band with the source spectral state and conclude that broad band variability is strongly correlated with the source hardness (or Comptonized fraction). We follow changes in the energy distribution of rms variability during the low-hard state and the state transition and find further evidence that variable emission is strongly concentrated in the power-law spectral component. We discuss the implication of our results to the Comptonization regimes during different spectral states. Correlations of spectral and variability properties provide measurements of the BH mass and distance to the source. The spectral-timing correlation scaling technique applied to the RXTE observations during the hardto- soft state transition indicates a mass of the BH in XTE J1752-223 between 8 and 11 solar masses and a distance to the source about 3.5 kiloparsec.

Consistency relations for sharp inflationary non-Gaussian features

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mooij, Sander; Palma, Gonzalo A.; Panotopoulos, Grigoris

If cosmic inflation suffered tiny time-dependent deviations from the slow-roll regime, these would induce the existence of small scale-dependent features imprinted in the primordial spectra, with their shapes and sizes revealing information about the physics that produced them. Small sharp features could be suppressed at the level of the two-point correlation function, making them undetectable in the power spectrum, but could be amplified at the level of the three-point correlation function, offering us a window of opportunity to uncover them in the non-Gaussian bispectrum. In this article, we show that sharp features may be analyzed using only data coming frommore » the three point correlation function parametrizing primordial non-Gaussianity. More precisely, we show that if features appear in a particular non-Gaussian triangle configuration (e.g. equilateral, folded, squeezed), these must reappear in every other configuration according to a specific relation allowing us to correlate features across the non-Gaussian bispectrum. As a result, we offer a method to study scale-dependent features generated during inflation that depends only on data coming from measurements of non-Gaussianity, allowing us to omit data from the power spectrum.« less

Direct modulation of aberrant brain network connectivity through real-time NeuroFeedback.

PubMed

Ramot, Michal; Kimmich, Sara; Gonzalez-Castillo, Javier; Roopchansingh, Vinai; Popal, Haroon; White, Emily; Gotts, Stephen J; Martin, Alex

2017-09-16

The existence of abnormal connectivity patterns between resting state networks in neuropsychiatric disorders, including Autism Spectrum Disorder (ASD), has been well established. Traditional treatment methods in ASD are limited, and do not address the aberrant network structure. Using real-time fMRI neurofeedback, we directly trained three brain nodes in participants with ASD, in which the aberrant connectivity has been shown to correlate with symptom severity. Desired network connectivity patterns were reinforced in real-time, without participants' awareness of the training taking place. This training regimen produced large, significant long-term changes in correlations at the network level, and whole brain analysis revealed that the greatest changes were focused on the areas being trained. These changes were not found in the control group. Moreover, changes in ASD resting state connectivity following the training were correlated to changes in behavior, suggesting that neurofeedback can be used to directly alter complex, clinically relevant network connectivity patterns.

Quantum-state transfer through long-range correlated disordered channels

NASA Astrophysics Data System (ADS)

Almeida, Guilherme M. A.; de Moura, Francisco A. B. F.; Lyra, Marcelo L.

2018-05-01

We study quantum-state transfer in XX spin-1/2 chains where both communicating spins are weakly coupled to a channel featuring disordered on-site magnetic fields. Fluctuations are modeled by long-range correlated sequences with self-similar profile obeying a power-law spectrum. We show that the channel is able to perform almost perfect quantum-state transmissions even in the presence of significant amounts of disorder provided the degree of those correlations is strong enough, with the cost of having long transfer times and unavoidable timing errors. Still, we show that the lack of mirror symmetry in the channel does not affect much the likelihood of having high-quality outcomes. Our results suggest that coexistence between localized and delocalized states can diminish effects of static perturbations in solid-state devices for quantum communication.

Ab initio model potential calculations on the electronic spectrum of Ni2 + -doped MgO including correlation, spin-orbit and embedding effects

NASA Astrophysics Data System (ADS)

Llusar, Rosa; Casarrubios, Marcos; Barandiarán, Zoila; Seijo, Luis

1996-10-01

An ab initio theoretical study of the optical absorption spectrum of Ni2+-doped MgO has been conducted by means of calculations in a MgO-embedded (NiO6)10-cluster. The calculations include long- and short-range embedding effects of electrostatic and quantum nature brought about by the MgO crystalline lattice, as well as electron correlation and spin-orbit effects within the (NiO6)10- cluster. The spin-orbit calculations have been performed using the spin-orbit-CI WB-AIMP method [Chem. Phys. Lett. 147, 597 (1988); J. Chem. Phys. 102, 8078 (1995)] which has been recently proposed and is applied here for the first time to the field of impurities in crystals. The WB-AIMP method is extended in order to handle correlation effects which, being necessary to produce accurate energy differences between spin-free states, are not needed for the proper calculation of spin-orbit couplings. The extension of the WB-AIMP method, which is also aimed at keeping the size of the spin-orbit-CI within reasonable limits, is based on the use of spin-free-state shifting operators. It is shown that the unreasonable spin-orbit splittings obtained for MgO:Ni2+ in spin-orbit-CI calculations correlating only 8 electrons become correct when the proposed extension is applied, so that the same CI space is used but energy corrections due to correlating up to 26 electrons are included. The results of the ligand field spectrum of MgO:Ni2+ show good overall agreement with the experimental measurements and a reassignment of the observed Eg(b3T1g) excited state is proposed and discussed.

The study of dielectric relaxation in aqueous carbohydrates solutions using time domain reflectometry technique

NASA Astrophysics Data System (ADS)

Hudge, Pravin G.; Lokhande, Milind P.; Kumbharkhane, Ashok C.

2012-09-01

Complex permittivity spectra of aqueous solutions of monosaccharide ( d-glucose) and disaccharides ( d-sucrose) in the frequency range from 10 MHz to 30 GHz at various concentrations and temperatures have been determined using time domain reflectometry technique. The complex dielectric permittivity spectrum of d-glucose and d-sucrose in water shows Cole-Davidson type behaviour. Dielectric constant (ɛ0) and relaxation time (τ), Kirkwood correlation factor, activation enthalpy and entropy parameters have been determined.

Singular spectrum decomposition of Bouligand-Minkowski fractal descriptors: an application to the classification of texture Images

NASA Astrophysics Data System (ADS)

Florindo, João. Batista

2018-04-01

This work proposes the use of Singular Spectrum Analysis (SSA) for the classification of texture images, more specifically, to enhance the performance of the Bouligand-Minkowski fractal descriptors in this task. Fractal descriptors are known to be a powerful approach to model and particularly identify complex patterns in natural images. Nevertheless, the multiscale analysis involved in those descriptors makes them highly correlated. Although other attempts to address this point was proposed in the literature, none of them investigated the relation between the fractal correlation and the well-established analysis employed in time series. And SSA is one of the most powerful techniques for this purpose. The proposed method was employed for the classification of benchmark texture images and the results were compared with other state-of-the-art classifiers, confirming the potential of this analysis in image classification.

Complex-valued time-series correlation increases sensitivity in FMRI analysis.

PubMed

Kociuba, Mary C; Rowe, Daniel B

2016-07-01

To develop a linear matrix representation of correlation between complex-valued (CV) time-series in the temporal Fourier frequency domain, and demonstrate its increased sensitivity over correlation between magnitude-only (MO) time-series in functional MRI (fMRI) analysis. The standard in fMRI is to discard the phase before the statistical analysis of the data, despite evidence of task related change in the phase time-series. With a real-valued isomorphism representation of Fourier reconstruction, correlation is computed in the temporal frequency domain with CV time-series data, rather than with the standard of MO data. A MATLAB simulation compares the Fisher-z transform of MO and CV correlations for varying degrees of task related magnitude and phase amplitude change in the time-series. The increased sensitivity of the complex-valued Fourier representation of correlation is also demonstrated with experimental human data. Since the correlation description in the temporal frequency domain is represented as a summation of second order temporal frequencies, the correlation is easily divided into experimentally relevant frequency bands for each voxel's temporal frequency spectrum. The MO and CV correlations for the experimental human data are analyzed for four voxels of interest (VOIs) to show the framework with high and low contrast-to-noise ratios in the motor cortex and the supplementary motor cortex. The simulation demonstrates the increased strength of CV correlations over MO correlations for low magnitude contrast-to-noise time-series. In the experimental human data, the MO correlation maps are noisier than the CV maps, and it is more difficult to distinguish the motor cortex in the MO correlation maps after spatial processing. Including both magnitude and phase in the spatial correlation computations more accurately defines the correlated left and right motor cortices. Sensitivity in correlation analysis is important to preserve the signal of interest in fMRI data sets with high noise variance, and avoid excessive processing induced correlation. Copyright © 2016 Elsevier Inc. All rights reserved.

Correlation spectrometer for filtering of (quasi) elastic neutron scattering with variable resolution

NASA Astrophysics Data System (ADS)

Magazù, Salvatore; Mezei, Ferenc; Migliardo, Federica

2018-05-01

In a variety of applications of inelastic neutron scattering spectroscopy the goal is to single out the elastic scattering contribution from the total scattered spectrum as a function of momentum transfer and sample environment parameters. The elastic part of the spectrum is defined in such a case by the energy resolution of the spectrometer. Variable elastic energy resolution offers a way to distinguish between elastic and quasi-elastic intensities. Correlation spectroscopy lends itself as an efficient, high intensity approach for accomplishing this both at continuous and pulsed neutron sources. On the one hand, in beam modulation methods the Liouville theorem coupling between intensity and resolution is relaxed and time-of-flight velocity analysis of the neutron velocity distribution can be performed with 50 % duty factor exposure for all available resolutions. On the other hand, the (quasi)elastic part of the spectrum generally contains the major part of the integrated intensity at a given detector, and thus correlation spectroscopy can be applied with most favorable signal to statistical noise ratio. The novel spectrometer CORELLI at SNS is an example for this type of application of the correlation technique at a pulsed source. On a continuous neutron source a statistical chopper can be used for quasi-random time dependent beam modulation and the total time-of-flight of the neutron from the statistical chopper to detection is determined by the analysis of the correlation between the temporal fluctuation of the neutron detection rate and the statistical chopper beam modulation pattern. The correlation analysis can either be used for the determination of the incoming neutron velocity or for the scattered neutron velocity, depending of the position of the statistical chopper along the neutron trajectory. These two options are considered together with an evaluation of spectrometer performance compared to conventional spectroscopy, in particular for variable resolution elastic neutron scattering (RENS) studies of relaxation processes and the evolution of mean square displacements. A particular focus of our analysis is the unique feature of correlation spectroscopy of delivering high and resolution independent beam intensity, thus the same statistical chopper scan contains both high intensity and high resolution information at the same time, and can be evaluated both ways. This flexibility for variable resolution data handling represents an additional asset for correlation spectroscopy in variable resolution work. Changing the beam width for the same statistical chopper allows us to additionally trade resolution for intensity in two different experimental runs, similarly for conventional single slit chopper spectroscopy. The combination of these two approaches is a capability of particular value in neutron spectroscopy studies requiring variable energy resolution, such as the systematic study of quasi-elastic scattering and mean square displacement. Furthermore the statistical chopper approach is particularly advantageous for studying samples with low scattering intensity in the presence of a high, sample independent background.

Enhanced t -3/2 long-time tail for the stress-stress time correlation function

NASA Astrophysics Data System (ADS)

Evans, Denis J.

1980-01-01

Nonequilibrium molecular dynamics is used to calculate the spectrum of shear viscosity for a Lennard-Jones fluid. The calculated zero-frequency shear viscosity agrees well with experimental argon results for the two state points considered. The low-frequency behavior of shear viscosity is dominated by an ω 1/2 cusp. Analysis of the form of this cusp reveals that the stress-stress time correlation function exhibits a t -3/2 "long-time tail." It is shown that for the state points studied, the amplitude of this long-time tail is between 12 and 150 times larger than what has been predicted theoretically. If the low-frequency results are truly asymptotic, they imply that the cross and potential contributions to the Kubo-Green integrand for shear viscosity exhibit a t -3/2 long-time tail. This result contradicts the established theory of such processes.

Magnitude and sign of long-range correlated time series: Decomposition and surrogate signal generation.

PubMed

Gómez-Extremera, Manuel; Carpena, Pedro; Ivanov, Plamen Ch; Bernaola-Galván, Pedro A

2016-04-01

We systematically study the scaling properties of the magnitude and sign of the fluctuations in correlated time series, which is a simple and useful approach to distinguish between systems with different dynamical properties but the same linear correlations. First, we decompose artificial long-range power-law linearly correlated time series into magnitude and sign series derived from the consecutive increments in the original series, and we study their correlation properties. We find analytical expressions for the correlation exponent of the sign series as a function of the exponent of the original series. Such expressions are necessary for modeling surrogate time series with desired scaling properties. Next, we study linear and nonlinear correlation properties of series composed as products of independent magnitude and sign series. These surrogate series can be considered as a zero-order approximation to the analysis of the coupling of magnitude and sign in real data, a problem still open in many fields. We find analytical results for the scaling behavior of the composed series as a function of the correlation exponents of the magnitude and sign series used in the composition, and we determine the ranges of magnitude and sign correlation exponents leading to either single scaling or to crossover behaviors. Finally, we obtain how the linear and nonlinear properties of the composed series depend on the correlation exponents of their magnitude and sign series. Based on this information we propose a method to generate surrogate series with controlled correlation exponent and multifractal spectrum.

A Gaussian Wave Packet Propagation Approach to Vibrationally Resolved Optical Spectra at Non-Zero Temperatures.

PubMed

Reddy, Ch Sridhar; Prasad, M Durga

2016-04-28

An effective time dependent approach based on a method that is similar to the Gaussian wave packet propagation (GWP) technique of Heller is developed for the computation of vibrationally resolved electronic spectra at finite temperatures in the harmonic, Franck-Condon/Hertzberg-Teller approximations. Since the vibrational thermal density matrix of the ground electronic surface and the time evolution operator on that surface commute, it is possible to write the spectrum generating correlation function as a trace of the time evolved doorway state. In the stated approximations, the doorway state is a superposition of the harmonic oscillator zero and one quantum eigenfunctions and thus can be propagated by the GWP. The algorithm has an O(N(3)) dependence on the number of vibrational modes. An application to pyrene absorption spectrum at two temperatures is presented as a proof of the concept.

Lévy distribution and long correlation times in supermarket sales

NASA Astrophysics Data System (ADS)

Groot, Robert D.

2005-08-01

Sales data in a commodity market (supermarket sales to consumers) has been analysed by studying the fluctuation spectrum and noise correlations. Three related products (ketchup, mayonnaise and curry sauce) have been analysed. Most noise in sales is caused by promotions, but here we focus on the fluctuations in baseline sales. These characterise the dynamics of the market. Four hitherto unnoticed effects have been found that are difficult to explain from simple econometric models. These effects are: (1) the noise level in baseline sales is much higher than can be expected for uncorrelated sales events; (2) weekly baseline sales differences are distributed according to a broad non-Gaussian function with fat tails; (3) these fluctuations follow a Lévy distribution of exponent α=1.4, similar to financial exchange markets and in stock markets; and (4) this noise is correlated over a period of 10-11 weeks, or shows an apparent power law spectrum. The similarity to stock markets suggests that models developed to describe these markets may be applied to describe the collective behaviour of consumers.

On the Direct Correlation between Gamma-Rays and PeV Neutrinos from Blazars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Shan; Pohl, Martin; Winter, Walter, E-mail: shan.gao@desy.de

We study the frequently used assumption in multi-messenger astrophysics that the gamma-ray and neutrino fluxes are directly connected because they are assumed to be produced by the same photohadronic production chain. An interesting candidate source for this test is the flat-spectrum radio quasar PKS B1424-418, which recently called attention to a potential correlation between an IceCube PeV neutrino event and its burst phase. We simulate both the multi-waveband photon and the neutrino emission from this source using a self-consistent radiation model. We demonstrate that a simple hadronic model cannot adequately describe the spectral energy distribution for this source, but amore » lepto-hadronic model with a subdominant hadronic component can reproduce the multi-waveband photon spectrum observed during various activity phases of the blazar. As a conclusion, up to about 0.3 neutrino events may coincide with the burst, which implies that the leptonic contribution dominates in the relevant energy band. We also demonstrate that the time-wise correlation between the neutrino event and burst phase is weak.« less

Time-Distance Helioseismology: Noise Estimation

NASA Astrophysics Data System (ADS)

Gizon, L.; Birch, A. C.

2004-10-01

As in global helioseismology, the dominant source of noise in time-distance helioseismology measurements is realization noise due to the stochastic nature of the excitation mechanism of solar oscillations. Characterizing noise is important for the interpretation and inversion of time-distance measurements. In this paper we introduce a robust definition of travel time that can be applied to very noisy data. We then derive a simple model for the full covariance matrix of the travel-time measurements. This model depends only on the expectation value of the filtered power spectrum and assumes that solar oscillations are stationary and homogeneous on the solar surface. The validity of the model is confirmed through comparison with SOHO MDI measurements in a quiet-Sun region. We show that the correlation length of the noise in the travel times is about half the dominant wavelength of the filtered power spectrum. We also show that the signal-to-noise ratio in quiet-Sun travel-time maps increases roughly as the square root of the observation time and is at maximum for a distance near half the length scale of supergranulation.

Probing reionization with the cross-power spectrum of 21 cm and near-infrared radiation backgrounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mao, Xiao-Chun, E-mail: xcmao@bao.ac.cn

2014-08-01

The cross-correlation between the 21 cm emission from the high-redshift intergalactic medium and the near-infrared (NIR) background light from high-redshift galaxies promises to be a powerful probe of cosmic reionization. In this paper, we investigate the cross-power spectrum during the epoch of reionization. We employ an improved halo approach to derive the distribution of the density field and consider two stellar populations in the star formation model: metal-free stars and metal-poor stars. The reionization history is further generated to be consistent with the electron-scattering optical depth from cosmic microwave background measurements. Then, the intensity of the NIR background is estimatedmore » by collecting emission from stars in first-light galaxies. On large scales, we find that the 21 cm and NIR radiation backgrounds are positively correlated during the very early stages of reionization. However, these two radiation backgrounds quickly become anti-correlated as reionization proceeds. The maximum absolute value of the cross-power spectrum is |Δ{sub 21,NIR}{sup 2}|∼10{sup −4} mK nW m{sup –2} sr{sup –1}, reached at ℓ ∼ 1000 when the mean fraction of ionized hydrogen is x-bar{sub i}∼0.9. We find that Square Kilometer Array can measure the 21 cm-NIR cross-power spectrum in conjunction with mild extensions to the existing CIBER survey, provided that the integration time independently adds up to 1000 and 1 hr for 21 cm and NIR observations, and that the sky coverage fraction of the CIBER survey is extended from 4 × 10{sup –4} to 0.1. Measuring the cross-correlation signal as a function of redshift provides valuable information on reionization and helps confirm the origin of the 'missing' NIR background.« less

Isotropy of the early universe from CMB anisotropies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Donoghue, Evan P.; University of Notre Dame, Notre Dame, Indiana 46556; Donoghue, John F.

The acoustic peak in the cosmic microwave background power spectrum is sensitive to causal processes and cosmological parameters in the early universe up to the time of last scattering. We provide limits on correlated spatial variations of the peak height and peak position and interpret these as constraints on the spatial variation of the cosmological parameters (baryon density, cold dark matter density, and cosmological constant as well as the amplitude and tilt of the original fluctuations). We utilize recent work of Hansen, Banday, and Gorski who have studied the spatial isotropy of the power spectrum as measured by WMAP bymore » performing the power spectrum analysis on smaller patches of the sky. We find that there is no statistically significant correlated asymmetry of the peak. Hansen, Banday, and Gorski have also provided preliminary indications of a preferred direction in the lower angular momentum range (l{approx}2-40) and we show how possible explanations of this asymmetry are severely constrained by the data on the acoustic peak. Finally we show a possible non-Gaussian feature in the data, associated with a difference in the northern and southern galactic hemispheres.« less

Passive advection of a vector field: Anisotropy, finite correlation time, exact solution, and logarithmic corrections to ordinary scaling

NASA Astrophysics Data System (ADS)

Antonov, N. V.; Gulitskiy, N. M.

2015-10-01

In this work we study the generalization of the problem considered in [Phys. Rev. E 91, 013002 (2015), 10.1103/PhysRevE.91.013002] to the case of finite correlation time of the environment (velocity) field. The model describes a vector (e.g., magnetic) field, passively advected by a strongly anisotropic turbulent flow. Inertial-range asymptotic behavior is studied by means of the field theoretic renormalization group and the operator product expansion. The advecting velocity field is Gaussian, with finite correlation time and preassigned pair correlation function. Due to the presence of distinguished direction n , all the multiloop diagrams in this model vanish, so that the results obtained are exact. The inertial-range behavior of the model is described by two regimes (the limits of vanishing or infinite correlation time) that correspond to the two nontrivial fixed points of the RG equations. Their stability depends on the relation between the exponents in the energy spectrum E ∝k⊥1 -ξ and the dispersion law ω ∝k⊥2 -η . In contrast to the well-known isotropic Kraichnan's model, where various correlation functions exhibit anomalous scaling behavior with infinite sets of anomalous exponents, here the corrections to ordinary scaling are polynomials of logarithms of the integral turbulence scale L .

Asymmetric correlation matrices: an analysis of financial data

NASA Astrophysics Data System (ADS)

Livan, G.; Rebecchi, L.

2012-06-01

We analyse the spectral properties of correlation matrices between distinct statistical systems. Such matrices are intrinsically non-symmetric, and lend themselves to extend the spectral analyses usually performed on standard Pearson correlation matrices to the realm of complex eigenvalues. We employ some recent random matrix theory results on the average eigenvalue density of this type of matrix to distinguish between noise and non-trivial correlation structures, and we focus on financial data as a case study. Namely, we employ daily prices of stocks belonging to the American and British stock exchanges, and look for the emergence of correlations between two such markets in the eigenvalue spectrum of their non-symmetric correlation matrix. We find several non trivial results when considering time-lagged correlations over short lags, and we corroborate our findings by additionally studying the asymmetric correlation matrix of the principal components of our datasets.

Effect of helicity on the correlation time of large scales in turbulent flows

NASA Astrophysics Data System (ADS)

Cameron, Alexandre; Alexakis, Alexandros; Brachet, Marc-Étienne

2017-11-01

Solutions of the forced Navier-Stokes equation have been conjectured to thermalize at scales larger than the forcing scale, similar to an absolute equilibrium obtained for the spectrally truncated Euler equation. Using direct numeric simulations of Taylor-Green flows and general-periodic helical flows, we present results on the probability density function, energy spectrum, autocorrelation function, and correlation time that compare the two systems. In the case of highly helical flows, we derive an analytic expression describing the correlation time for the absolute equilibrium of helical flows that is different from the E-1 /2k-1 scaling law of weakly helical flows. This model predicts a new helicity-based scaling law for the correlation time as τ (k ) ˜H-1 /2k-1 /2 . This scaling law is verified in simulations of the truncated Euler equation. In simulations of the Navier-Stokes equations the large-scale modes of forced Taylor-Green symmetric flows (with zero total helicity and large separation of scales) follow the same properties as absolute equilibrium including a τ (k ) ˜E-1 /2k-1 scaling for the correlation time. General-periodic helical flows also show similarities between the two systems; however, the largest scales of the forced flows deviate from the absolute equilibrium solutions.

A phenomenological treatment of rotating turbulence

NASA Technical Reports Server (NTRS)

Zhou, YE

1995-01-01

The strong similarity between the magnetohydrodynamic (MHD) turbulence and initially isotropic turbulence subject to rotation is noted. We then apply the MHD phenomenologies of Kraichnan and Matthaeus & Zhou to rotating turbulence. When the turbulence is subject to a strong rotation, the energy spectrum is found to scale as E(k) = C(sub Omega)(Omega(sub epsilon))(sup 1/2)k(sup -2), where Omega is the rotation rate, k is the wavenumber, and epsilon is the dissipation rate. This spectral form is consistent with a recent letter by Zeman. However, here the constant C(sub Omega) is found to be related to the Kolmogorov constant and is estimated in the range 1.22 - 1.87 for the typical values of the latter constant. A 'rule' that relates spectral transfer times to the eddy turnover time and the time scale for decay of the triple correlations is deduced. A hypothesis for the triple correlation decay rate leads to the spectral law which varies between the '-5/3' (without rotation) and '-2' laws (with strong rotation). For intermediate rotation rates, the spectrum varies according to the value of a dimensionless parameter that measures the strength of the rotation wavenumber k(sub Omega) = (Omega(sup 3)/epsiolon)(sup 1/2) relative to the wavenumber k. An eddy viscosity is derived with an explicit dependence on the rotation rate.

The full-sky relativistic correlation function and power spectrum of galaxy number counts. Part I: theoretical aspects

NASA Astrophysics Data System (ADS)

Tansella, Vittorio; Bonvin, Camille; Durrer, Ruth; Ghosh, Basundhara; Sellentin, Elena

2018-03-01

We derive an exact expression for the correlation function in redshift shells including all the relativistic contributions. This expression, which does not rely on the distant-observer or flat-sky approximation, is valid at all scales and includes both local relativistic corrections and integrated contributions, like gravitational lensing. We present two methods to calculate this correlation function, one which makes use of the angular power spectrum Cl(z1,z2) and a second method which evades the costly calculations of the angular power spectra. The correlation function is then used to define the power spectrum as its Fourier transform. In this work theoretical aspects of this procedure are presented, together with quantitative examples. In particular, we show that gravitational lensing modifies the multipoles of the correlation function and of the power spectrum by a few percent at redshift z=1 and by up to 30% and more at z=2. We also point out that large-scale relativistic effects and wide-angle corrections generate contributions of the same order of magnitude and have consequently to be treated in conjunction. These corrections are particularly important at small redshift, z=0.1, where they can reach 10%. This means in particular that a flat-sky treatment of relativistic effects, using for example the power spectrum, is not consistent.

Passive Synthetic Aperture Radar Imaging Using Commercial OFDM Communication Networks

DTIC Science & Technology

2012-09-13

baseband sampling is key to ensure proper correlation with a reference signal. The DFT represents the sam- pled spectrum of a periodic discrete sequence...convenient to sample the baseband time domain segments at a rate of Ts/N . In this way, the segments are easily correlated to the elemental form of the...phase history solution of Gp ,l[k ′ n] = Sp,l,n ϕp,l,ndp,l,nN2 , dp,l,n 6= 0. (5.5.13) The segment need not be limited to N samples . For segments of length

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khan, Shiraj; Ganguly, Auroop R; Bandyopadhyay, Sharba

Cross-spectrum analysis based on linear correlations in the time domain suggested a coupling between large river flows and the El Nino-Southern Oscillation (ENSO) cycle. A nonlinear measure based on mutual information (MI) reveals extrabasinal connections between ENSO and river flows in the tropics and subtropics, that are 20-70% higher than those suggested so far by linear correlations. The enhanced dependence observed for the Nile, Amazon, Congo, Paran{acute a}, and Ganges rivers, which affect large, densely populated regions of the world, has significant impacts on inter-annual river flow predictabilities and, hence, on water resources and agricultural planning.

Temperature dependent structural and dynamical properties of liquid Cu80Si20 binary alloy

NASA Astrophysics Data System (ADS)

Suthar, P. H.; Shah, A. K.; Gajjar, P. N.

2018-05-01

Ashcroft and Langreth binary structure factor have been used to study for pair correlation function and the study of dynamical variable: velocity auto correlation functions, power spectrum and mean square displacement calculated based on the static harmonic well approximation in liquid Cu80Si20 binary alloy at wide temperature range (1140K, 1175K, 1210K, 1250K, 1373K, 1473K.). The effective interaction for the binary alloy is computed by our well established local pseudopotential along with the exchange and correction functions Sarkar et al(S). The negative dip in velocity auto correlation decreases as the various temperature is increases. For power spectrum as temperature increases, the peak of power spectrum shifts toward lower ω. Good agreement with the experiment is observed for the pair correlation functions. Velocity auto correlation showing the transferability of the local pseudopotential used for metallic liquid environment in the case of copper based binary alloys.

Self-synchronization for spread spectrum audio watermarks after time scale modification

NASA Astrophysics Data System (ADS)

Nadeau, Andrew; Sharma, Gaurav

2014-02-01

De-synchronizing operations such as insertion, deletion, and warping pose significant challenges for watermarking. Because these operations are not typical for classical communications, watermarking techniques such as spread spectrum can perform poorly. Conversely, specialized synchronization solutions can be challenging to analyze/ optimize. This paper addresses desynchronization for blind spread spectrum watermarks, detected without reference to any unmodified signal, using the robustness properties of short blocks. Synchronization relies on dynamic time warping to search over block alignments to find a sequence with maximum correlation to the watermark. This differs from synchronization schemes that must first locate invariant features of the original signal, or estimate and reverse desynchronization before detection. Without these extra synchronization steps, analysis for the proposed scheme builds on classical SS concepts and allows characterizes the relationship between the size of search space (number of detection alignment tests) and intrinsic robustness (continuous search space region covered by each individual detection test). The critical metrics that determine the search space, robustness, and performance are: time-frequency resolution of the watermarking transform, and blocklength resolution of the alignment. Simultaneous robustness to (a) MP3 compression, (b) insertion/deletion, and (c) time-scale modification is also demonstrated for a practical audio watermarking scheme developed in the proposed framework.

A long time ago, where were the galaxies far, far away?

NASA Astrophysics Data System (ADS)

Sirko, Edwin

How did the universe get from then to now ? I examine this broad cosmological problem from two perspectives: forward and backward. In the forward perspective, I implement a method of generating initial conditions for N -body simulations that accurately models real-space statistical properties, such as the mass variance in spheres and the correlation function. The method requires running ensembles of simulations because the power in the DC mode is no longer assumed to be zero. For moderately sized boxes, I demonstrate that the new method corrects the previously widely ignored underestimate in the mass variance in spheres and the shape of the correlation function. In the backward perspective, I use reconstruction techniques to transform a simulated or observed cosmological density field back in time to the early universe. A simple reconstruction technique is used to sharpen the baryon acoustic peak in the correlation function in simulations. At z = 0.3, one can reduce the sample variance error bar on the acoustic scale by at least a factor of 2 and in principle by nearly a factor of 4. This has significant implications for future observational surveys aiming to measure the cosmological distance scale. Another reconstruction technique, Monge-Ampere-Kantorovich reconstruction, is used on evolved N -body simulations to calibrate its effectiveness in recovering the linear power spectrum. A new "memory model" parametrizes the evolution of Fourier modes into two parameters that describe the amount of memory a given mode retains and how much the mode has been scrambled by nonlinear evolution. Reconstruction is spectacularly successful in restoring the memory of Fourier modes and reducing the scrambling; however, the success of reconstruction is not so obvious when considering the power spectrum alone. I apply reconstruction to a volume-limited sample of galaxies from the Sloan Digital Sky Survey and conclude that linear bias is not a good model in the range 0.01 h Mpc -1 [Special characters omitted.] k [Special characters omitted.] 0.5 h Mpc -1 . The most impressive success of reconstruction applied to real data is that the confidence interval on the normalization of the power spectrum is typically halved when using the reconstructed instead of the nonlinear power spectrum.

Two-dimensional electronic spectroscopy signatures of the glass transition

DOE PAGES

Lewis, K. L. .. M.; Myers, J. A.; Fuller, F.; ...

2010-01-01

Two-dimensional electronic spectroscopy is a sensitive probe of solvation dynamics. Using a pump–probe geometry with a pulse shaper [ Optics Express 15 (2007), 16681-16689; Optics Express 16 (2008), 17420-17428], we present temperature dependent 2D spectra of laser dyes dissolved in glass-forming solvents. At low waiting times, the system has not yet relaxed, resulting in a spectrum that is elongated along the diagonal. At longer times, the system loses its memory of the initial excitation frequency, and the 2D spectrum rounds out. As the temperature is lowered, the time scale of this relaxation grows, and the elongation persists for longer waitingmore » times. This can be measured in the ratio of the diagonal width to the anti-diagonal width; the behavior of this ratio is representative of the frequency–frequency correlation function [ Optics Letters 31 (2006), 3354–3356]. Near the glass transition temperature, the relaxation behavior changes. Understanding this change is important for interpreting temperature-dependent dynamics of biological systems.« less

Are We Under-Estimating the Association between Autism Symptoms?: The Importance of Considering Simultaneous Selection When Using Samples of Individuals Who Meet Diagnostic Criteria for an Autism Spectrum Disorder

ERIC Educational Resources Information Center

Murray, Aja Louise; McKenzie, Karen; Kuenssberg, Renate; O'Donnell, Michael

2014-01-01

The magnitude of symptom inter-correlations in diagnosed individuals has contributed to the evidence that autism spectrum disorders (ASD) is a fractionable disorder. Such correlations may substantially under-estimate the population correlations among symptoms due to simultaneous selection on the areas of deficit required for diagnosis. Using…

Demographic and Clinical Correlates of Autism Symptom Domains and Autism Spectrum Diagnosis

ERIC Educational Resources Information Center

Frazier, Thomas W.; Youngstrom, Eric A.; Embacher, Rebecca; Hardan, Antonio Y.; Constantino, John N.; Law, Paul; Findling, Robert L.; Eng, Charis

2014-01-01

Demographic and clinical factors may influence assessment of autism symptoms. This study evaluated these correlates and also examined whether social communication and interaction and restricted/repetitive behavior provided unique prediction of autism spectrum disorder diagnosis. We analyzed data from 7352 siblings included in the Interactive…

Incidence and Behavioral Correlates of Epileptiform Abnormalities in Autism Spectrum Disorders

ERIC Educational Resources Information Center

Mulligan, Caitlin K.; Trauner, Doris A.

2014-01-01

Autism spectrum disorders (ASD) are associated with an increased incidence of epilepsy and of epileptiform discharges on electroencephalograms. It is unknown whether epileptiform discharges correlate with symptoms of ASD. We completed a retrospective chart review of 101 patients with ASD who had overnight electroencephalograms. We looked for a…

Kinetic evolution and correlation of fluctuations in an expanding quark gluon plasma

NASA Astrophysics Data System (ADS)

Sarwar, Golam; Alam, Jan-E.

2018-03-01

Evolution of spatially anisotropic perturbation created in the system formed after Relativistic Heavy Ion Collisions has been studied. The microscopic evolution of the fluctuations has been examined within the ambit of Boltzmann Transport Equation (BTE) in a hydrodynamically expanding background. The expansion of the background composed of quark gluon plasma (QGP) is treated within the framework of relativistic hydrodynamics. Spatial anisotropic fluctuations with different geometries have been evolved through Boltzmann equation. It is observed that the trace of such fluctuation survives the evolution. Within the relaxation time approximation, analytical results have been obtained for the evolution of these anisotropies. Explicit relations between fluctuations and transport coefficients have been derived. The mixing of various Fourier (or k) modes of the perturbations during the evolution of the system has been explicitly demonstrated. This study is very useful in understanding the presumption that the measured anisotropies in the data from heavy ion collisions at relativistic energies imitate the initial state effects. The evolution of correlation function for the perturbation in pressure has been studied and shows that the initial correlation between two neighbouring points in real space evolves to a constant value at later time which gives rise to Dirac delta function for the correlation function in Fourier space. The power spectrum of the fluctuation in thermodynamic quantities (like temperature estimated in this work) can be connected to the fluctuation in transverse momentum of the thermal hadrons measured experimentally. The bulk viscous coefficient of the QGP has been estimated by using correlations of pressure fluctuation with the help of Green-Kubo relation. Angular power spectrum of the anisotropies has been estimated in the appendix.

POLARBEAR constraints on cosmic birefringence and primordial magnetic fields

DOE PAGES

Ade, Peter A. R.; Arnold, Kam; Atlas, Matt; ...

2015-12-08

Here, we constrain anisotropic cosmic birefringence using four-point correlations of even-parity E-mode and odd-parity B-mode polarization in the cosmic microwave background measurements made by the POLARization of the Background Radiation (POLARBEAR) experiment in its first season of observations. We find that the anisotropic cosmic birefringence signal from any parity-violating processes is consistent with zero. The Faraday rotation from anisotropic cosmic birefringence can be compared with the equivalent quantity generated by primordial magnetic fields if they existed. The POLARBEAR nondetection translates into a 95% confidence level (C.L.) upper limit of 93 nanogauss (nG) on the amplitude of an equivalent primordial magneticmore » field inclusive of systematic uncertainties. This four-point correlation constraint on Faraday rotation is about 15 times tighter than the upper limit of 1380 nG inferred from constraining the contribution of Faraday rotation to two-point correlations of B-modes measured by Planck in 2015. Metric perturbations sourced by primordial magnetic fields would also contribute to the B-mode power spectrum. Using the POLARBEAR measurements of the B-mode power spectrum (two-point correlation), we set a 95% C.L. upper limit of 3.9 nG on primordial magnetic fields assuming a flat prior on the field amplitude. This limit is comparable to what was found in the Planck 2015 two-point correlation analysis with both temperature and polarization. Finally, we perform a set of systematic error tests and find no evidence for contamination. This work marks the first time that anisotropic cosmic birefringence or primordial magnetic fields have been constrained from the ground at subdegree scales.« less

Boson peak dynamics of natural polymer starch investigated by terahertz time-domain spectroscopy and low-frequency Raman scattering

NASA Astrophysics Data System (ADS)

Terao, Wakana; Mori, Tatsuya; Fujii, Yasuhiro; Koreeda, Akitoshi; Kabeya, Mikitoshi; Kojima, Seiji

2018-03-01

Terahertz time-domain spectroscopy and low-frequency Raman scattering were performed on the natural polymer starch to investigate the boson peak (BP) dynamics. In the infrared spectrum, the BP was observed at 0.99 THz at the lowest temperature. Compared to the result from a previous study for vitreous glucose, both the frequency of the BP and absorption coefficient show lower values than those of the vitreous glucose. These behaviors originate from the longer correlation length of the medium-range order and lower concentration of hydroxyl groups in the starch. In the Raman spectrum, the BP was observed at 1.1 THz at room temperature, although the BP was not observed around room temperature due to the excess wing of the fast relaxation modes in the infrared spectrum. The temperature dependence of ε″(ν) during the heating process and cooling process shows a hysteresis below 230 K. During the heating process, kinks were observed at 140 K and 230 K. These kinks are attributed to the β-relaxation and the βwet-relaxation, respectively.

Redshift space clustering of galaxies and cold dark matter model

NASA Technical Reports Server (NTRS)

Bahcall, Neta A.; Cen, Renyue; Gramann, Mirt

1993-01-01

The distorting effect of peculiar velocities on the power speturm and correlation function of IRAS and optical galaxies is studied. The observed redshift space power spectra and correlation functions of IRAS and optical the galaxies over the entire range of scales are directly compared with the corresponding redshift space distributions using large-scale computer simulations of cold dark matter (CDM) models in order to study the distortion effect of peculiar velocities on the power spectrum and correlation function of the galaxies. It is found that the observed power spectrum of IRAS and optical galaxies is consistent with the spectrum of an Omega = 1 CDM model. The problems that such a model currently faces may be related more to the high value of Omega in the model than to the shape of the spectrum. A low-density CDM model is also investigated and found to be consistent with the data.

Modified DFA and DCCA approach for quantifying the multiscale correlation structure of financial markets

NASA Astrophysics Data System (ADS)

Yin, Yi; Shang, Pengjian

2013-12-01

We use multiscale detrended fluctuation analysis (MSDFA) and multiscale detrended cross-correlation analysis (MSDCCA) to investigate auto-correlation (AC) and cross-correlation (CC) in the US and Chinese stock markets during 1997-2012. The results show that US and Chinese stock indices differ in terms of their multiscale AC structures. Stock indices in the same region also differ with regard to their multiscale AC structures. We analyze AC and CC behaviors among indices for the same region to determine similarity among six stock indices and divide them into four groups accordingly. We choose S&P500, NQCI, HSI, and the Shanghai Composite Index as representative samples for simplicity. MSDFA and MSDCCA results and average MSDFA spectra for local scaling exponents (LSEs) for individual series are presented. We find that the MSDCCA spectrum for LSE CC between two time series generally tends to be greater than the average MSDFA LSE spectrum for individual series. We obtain detailed multiscale structures and relations for CC between the four representatives. MSDFA and MSDCCA with secant rolling windows of different sizes are then applied to reanalyze the AC and CC. Vertical and horizontal comparisons of different window sizes are made. The MSDFA and MSDCCA results for the original window size are confirmed and some new interesting characteristics and conclusions regarding multiscale correlation structures are obtained.

SCALAR MULTI-PASS ATOMIC MAGNETOMETER

DTIC Science & Technology

2017-08-01

primarily by atomic shot noise. Furthermore, the spectrum of quantum spin noise provides information on the time correlation between the spins and...the resulting light to be shot -noise-limited both with and without the polarizer in place. Newer Vixar VCSELs with internal gratings on output...described on inside pages STINFO COPY AIR FORCE RESEARCH LABORATORY SENSORS DIRECTORATE WRIGHT-PATTERSON AIR FORCE BASE, OH 45433-7320

[Secondary Raman spectrum of beta-carotene molecule in living leaf of French phoenix tree].

PubMed

Zhao, Jin-tao; Zhang, Peng-xiang; Xu, Cun-ying

2002-10-01

Under visible incidence light 514.5 nm, the Raman scattering spectrum from the beta-carotene molecule in the leaf was directly obtained after it was immediately collected from French phoenix tree without any preparing the sample but cleaning. It is very easy to collect the secondary Raman lines addition to the first Raman spectrum in situ by micro Raman. By careful comparing and analyzing the Raman lines between 2,000-3,100 cm-1 and below 2,000 cm-1 regions, we obtained the correlated relation of the first and secondary Raman lines. The study results indicated that there is no damage to the structure and configuration of beta-carotene molecule in the live leaf by controlling laser power on the sample surface and integrating time for Raman signal, but large power laser or long time irradiation on the live sample would cause very strong fluorescence background in Raman spectrum which indicated that there is a photo damage in the center of photo reaction. The Micro Raman would become one of possible in situ methods for investigating live plant molecules growing up in different environment. At last we proposed and discussed the advantages and limits in micro Raman when it is applied to investigating live molecules in botany field.

Measuring out-of-time-order correlations and multiple quantum spectra in a trapped-ion quantum magnet

NASA Astrophysics Data System (ADS)

Gärttner, Martin; Bohnet, Justin G.; Safavi-Naini, Arghavan; Wall, Michael L.; Bollinger, John J.; Rey, Ana Maria

2017-08-01

Controllable arrays of ions and ultracold atoms can simulate complex many-body phenomena and may provide insights into unsolved problems in modern science. To this end, experimentally feasible protocols for quantifying the buildup of quantum correlations and coherence are needed, as performing full state tomography does not scale favourably with the number of particles. Here we develop and experimentally demonstrate such a protocol, which uses time reversal of the many-body dynamics to measure out-of-time-order correlation functions (OTOCs) in a long-range Ising spin quantum simulator with more than 100 ions in a Penning trap. By measuring a family of OTOCs as a function of a tunable parameter we obtain fine-grained information about the state of the system encoded in the multiple quantum coherence spectrum, extract the quantum state purity, and demonstrate the buildup of up to 8-body correlations. Future applications of this protocol could enable studies of many-body localization, quantum phase transitions, and tests of the holographic duality between quantum and gravitational systems.

Genetic correlation between autistic traits and IQ in a population-based sample of twins with autism spectrum disorders (ASDs).

PubMed

Nishiyama, Takeshi; Taniai, Hiroko; Taniai, Hitomi; Miyachi, Taishi; Ozaki, Koken; Tomita, Makoto; Sumi, Satoshi

2009-01-01

Although there is accumulating evidence that intelligence quotient (IQ) indexes some aspects of the autistic spectrum disorders (ASDs), the causal relationship between autistic traits and IQ remains controversial. We examined the sources of covariation between autistic traits and IQ. As males have a four times greater risk of ASDs than females, gender-specific effects were also explored. Autistic traits and IQ were assessed in 45 twin male-male, female-female and opposite-sex pairs ascertained by the regional screening system in Nagoya, Japan. Sex-limited Cholesky structural equation models were used to decompose the correlations between autistic traits and IQ into genetic and environmental components, including sex-specific factors. Genetic correlations between autistic traits and IQ were high and not significantly different between boys and girls (-0.94 and -0.95, respectively), but genetic factors underlying the autistic traits were not entirely shared with the IQ. The individual-specific environmental correlation between autistic traits and IQ was estimated at -0.29 for boys and -0.59 for girls. There is a substantial overlap between the genetic factors that influence individual variation in autistic traits and IQ, irrespective of gender. The individual life experiences that increase autistic traits, however, have a moderate overlap with those that contribute to individual IQs.

Quiet-Time Suprathermal ( 0.1-1.5 keV) Electrons in the Solar Wind

NASA Astrophysics Data System (ADS)

Wang, L.; Tao, J.; Zong, Q.; Li, G.; Salem, C. S.; Wimmer-Schweingruber, R. F.; He, J.; Tu, C.; Bale, S. D.

2016-12-01

We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND/3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity).

Quiet-time Suprathermal (~0.1-1.5 keV) Electrons in the Solar Wind

NASA Astrophysics Data System (ADS)

Tao, Jiawei; Wang, Linghua; Zong, Qiugang; Li, Gang; Salem, Chadi S.; Wimmer-Schweingruber, Robert F.; He, Jiansen; Tu, Chuanyi; Bale, Stuart D.

2016-03-01

We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity).

Prevalence and Correlates of Educational Intervention Utilization among Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Bilaver, Lucy A.; Cushing, Lisa S.; Cutler, Ann T.

2016-01-01

This study examined the prevalence and correlates of educational intervention utilization among U.S. preschool aged children with autism spectrum disorder (ASD) prior to recent policy changes. The analysis was based on a nationally representative longitudinal survey of children receiving special education services during the 2003-2004 school year.…

Assessing Gestures in Young Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Ellawadi, Allison Bean; Weismer, Susan Ellis

2014-01-01

Purpose: The purpose of this study was to determine whether scoring of the gestures point, give, and show were correlated across measurement tools used to assess gesture production in children with an autism spectrum disorder (ASD). Method: Seventy-eight children with ASD between the ages of 23 and 37 months participated. Correlational analyses…

A Brief Report: Quantifying and Correlating Social Behaviors in Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Johnson, Ashley L.; Gillis, Jennifer M.; Romanczyk, Raymond G.

2012-01-01

The current study investigated social behaviors, including initiating joint attention (IJA), responding to joint attention (RJA), social orienting, and imitation in 14 children with an autism spectrum disorder (ASD) compared to 12 typically developing children (TD). Results indicated that IJA and RJA were positively correlated with social…

Hoarding in Youth with Autism Spectrum Disorders and Anxiety: Incidence, Clinical Correlates, and Behavioral Treatment Response

ERIC Educational Resources Information Center

Storch, Eric A.; Nadeau, Joshua M.; Johnco, Carly; Timpano, Kiara; McBride, Nicole; Mutch, P. Jane; Lewin, Adam B.; Murphy, Tanya K.

2016-01-01

This study examined the nature and correlates of hoarding among youth with autism spectrum disorders (ASD). Forty children with ASD and a comorbid anxiety disorder were administered a battery of clinician-administered measures assessing presence of psychiatric disorders and anxiety severity. Parents completed questionnaires related to child…

On estimating attenuation from the amplitude of the spectrally whitened ambient seismic field

NASA Astrophysics Data System (ADS)

Weemstra, Cornelis; Westra, Willem; Snieder, Roel; Boschi, Lapo

2014-06-01

Measuring attenuation on the basis of interferometric, receiver-receiver surface waves is a non-trivial task: the amplitude, more than the phase, of ensemble-averaged cross-correlations is strongly affected by non-uniformities in the ambient wavefield. In addition, ambient noise data are typically pre-processed in ways that affect the amplitude itself. Some authors have recently attempted to measure attenuation in receiver-receiver cross-correlations obtained after the usual pre-processing of seismic ambient-noise records, including, most notably, spectral whitening. Spectral whitening replaces the cross-spectrum with a unit amplitude spectrum. It is generally assumed that cross-terms have cancelled each other prior to spectral whitening. Cross-terms are peaks in the cross-correlation due to simultaneously acting noise sources, that is, spurious traveltime delays due to constructive interference of signal coming from different sources. Cancellation of these cross-terms is a requirement for the successful retrieval of interferometric receiver-receiver signal and results from ensemble averaging. In practice, ensemble averaging is replaced by integrating over sufficiently long time or averaging over several cross-correlation windows. Contrary to the general assumption, we show in this study that cross-terms are not required to cancel each other prior to spectral whitening, but may also cancel each other after the whitening procedure. Specifically, we derive an analytic approximation for the amplitude difference associated with the reversed order of cancellation and normalization. Our approximation shows that an amplitude decrease results from the reversed order. This decrease is predominantly non-linear at small receiver-receiver distances: at distances smaller than approximately two wavelengths, whitening prior to ensemble averaging causes a significantly stronger decay of the cross-spectrum.

Characteristic Lifelength of Coherent Structure in the Turbulent Boundary Layer

NASA Technical Reports Server (NTRS)

Palumbo, Daniel L.

2006-01-01

A characteristic lifelength is defined by which a Gaussian distribution is fit to data correlated over a 3 sensor array sampling streamwise sidewall pressure. The data were acquired at subsonic, transonic and supersonic speeds aboard a Tu-144. Lifelengths are estimated using the cross spectrum and are shown to compare favorably with Efimtsov's prediction of correlation space scales. Lifelength distributions are computed in the time/frequency domain using an interval correlation technique on the continuous wavelet transform of the original time data. The median values of the lifelength distributions are found to be very close to the frequency averaged result. The interval correlation technique is shown to allow the retrieval and inspection of the original time data of each event in the lifelength distribution, thus providing a means to locate and study the nature of the coherent structure in the turbulent boundary layer. The lifelength data can be converted to lifetimes using the convection velocity. The lifetime of events in the time/frequency domain are displayed in Lifetime Maps. The primary purpose of the paper is to validate these new analysis techniques so that they can be used with confidence to further characterize coherent structure in the turbulent boundary layer.

Direct modulation of aberrant brain network connectivity through real-time NeuroFeedback

PubMed Central

Kimmich, Sara; Gonzalez-Castillo, Javier; Roopchansingh, Vinai; Popal, Haroon; White, Emily; Gotts, Stephen J; Martin, Alex

2017-01-01

The existence of abnormal connectivity patterns between resting state networks in neuropsychiatric disorders, including Autism Spectrum Disorder (ASD), has been well established. Traditional treatment methods in ASD are limited, and do not address the aberrant network structure. Using real-time fMRI neurofeedback, we directly trained three brain nodes in participants with ASD, in which the aberrant connectivity has been shown to correlate with symptom severity. Desired network connectivity patterns were reinforced in real-time, without participants’ awareness of the training taking place. This training regimen produced large, significant long-term changes in correlations at the network level, and whole brain analysis revealed that the greatest changes were focused on the areas being trained. These changes were not found in the control group. Moreover, changes in ASD resting state connectivity following the training were correlated to changes in behavior, suggesting that neurofeedback can be used to directly alter complex, clinically relevant network connectivity patterns. PMID:28917059

Quasinormal modes of a strongly coupled nonconformal plasma and approach to criticality

NASA Astrophysics Data System (ADS)

Betzios, Panagiotis; Gürsoy, Umut; Järvinen, Matti; Policastro, Giuseppe

2018-04-01

We study fluctuations around equilibrium in a class of strongly interacting nonconformal plasmas using holographic techniques. In particular, we calculate the quasinormal mode spectrum of black hole backgrounds that approach Chamblin-Reall plasmas in the IR. In a specific limit, related to the exact linear-dilaton background in string theory, we observe that the plasma approaches criticality and we obtain the quasinormal spectrum analytically. We regulate the critical limit by gluing the IR geometry that corresponds to the nonconformal plasma to a part of AdS space-time in the UV. Near criticality, the spectrum can still be computed analytically and we find two sets of quasinormal modes, related to the IR and UV parts of the geometry. In the critical limit, the quasinormal modes accumulate to form a branch cut in the correlators of the energy-momentum tensor on the real axis of the complex frequency plane.

Modulation of cosmic-ray protons and helium nuclei near solar maximum

NASA Technical Reports Server (NTRS)

Rygg, T. A.; Ogallagher, J. J.; Earl, J. A.

1974-01-01

Balloon observations of proton and helium spectra in 1970, 1971 and 1972, reveal a factor of approximately 1.85 deviation from a single valued regression at low rigidities. This deviation decreases with increasing rigidity for both species. The period 1969-1970 is unique because time variations at low and high energies were anti-correlated. When satellite observations are used to extend the balloon observations to energies below 100 MeV/Nucleon, the proton spectrum showed a steeper slope in 1970 and 1972 than the characteristic J = AT spectrum observed during 1965-1969. The slope of the helium spectrum became continuously flatter during the same period (1970-1972). Computer generated spectra based on simple two parameter modulation models describe the basic features of the observations if one of the variable parameters is used to characterize the rigidity dependence of the diffusion coefficient. Models which do not allow such a variation are not consistent with the observations.

Joint multifractal analysis based on the partition function approach: analytical analysis, numerical simulation and empirical application

NASA Astrophysics Data System (ADS)

Xie, Wen-Jie; Jiang, Zhi-Qiang; Gu, Gao-Feng; Xiong, Xiong; Zhou, Wei-Xing

2015-10-01

Many complex systems generate multifractal time series which are long-range cross-correlated. Numerous methods have been proposed to characterize the multifractal nature of these long-range cross correlations. However, several important issues about these methods are not well understood and most methods consider only one moment order. We study the joint multifractal analysis based on partition function with two moment orders, which was initially invented to investigate fluid fields, and derive analytically several important properties. We apply the method numerically to binomial measures with multifractal cross correlations and bivariate fractional Brownian motions without multifractal cross correlations. For binomial multifractal measures, the explicit expressions of mass function, singularity strength and multifractal spectrum of the cross correlations are derived, which agree excellently with the numerical results. We also apply the method to stock market indexes and unveil intriguing multifractality in the cross correlations of index volatilities.

[Research on rapid and quantitative detection method for organophosphorus pesticide residue].

PubMed

Sun, Yuan-Xin; Chen, Bing-Tai; Yi, Sen; Sun, Ming

2014-05-01

The methods of physical-chemical inspection is adopted in the traditional pesticide residue detection, which require a lot of pretreatment processes, are time-consuming and complicated. In the present study, the authors take chlorpyrifos applied widely in the present agricultural field as the research object and propose a rapid and quantitative detection method for organophosphorus pesticide residues. At first, according to the chemical characteristics of chlorpyrifos and comprehensive chromogenic effect of several colorimetric reagents and secondary pollution, the pretreatment of the scheme of chromogenic reaction of chlorpyrifos with resorcin in a weak alkaline environment was determined. Secondly, by analyzing Uv-Vis spectrum data of chlorpyrifos samples whose content were between 0. 5 and 400 mg kg-1, it was confirmed that the characteristic information after the color reaction mainly was concentrated among 360 approximately 400 nm. Thirdly, the full spectrum forecasting model was established based on the partial least squares, whose correlation coefficient of calibration was 0. 999 6, correlation coefficient of prediction reached 0. 995 6, standard deviation of calibration (RMSEC) was 2. 814 7 mg kg-1, and standard deviation of verification (RMSEP) was 8. 012 4 mg kg-1. Fourthly, the wavelengths whose center wavelength is 400 nm was extracted as characteristic region to build a forecasting model, whose correlation coefficient of calibration was 0. 999 6, correlation coefficient of prediction reached 0. 999 3, standard deviation of calibration (RMSEC) was 2. 566 7 mg kg-1 , standard deviation of verification (RMSEP) was 4. 886 6 mg kg-1, respectively. At last, by analyzing the near infrared spectrum data of chlorpyrifos samples with contents between 0. 5 and 16 mg kg-1, the authors found that although the characteristics of the chromogenic functional group are not obvious, the change of absorption peaks of resorcin itself in the neighborhood of 5 200 cm-' happens. The above-mentioned experimental results show that the proposed method is effective and feasible for rapid and quantitative detection prediction for organophosphorus pesticide residues. In the method, the information in full spectrum especially UV-Vis spectrum is strengthened by chromogenic reaction of a colorimetric reagent, which provides a new way of rapid detection of pesticide residues for agricultural products in the future.

Aging Wire Insulation Assessment by Phase Spectrum Examination of Ultrasonic Guided Waves

NASA Technical Reports Server (NTRS)

Anastasi, Robert F.; Madaras, Eric I.

2003-01-01

Wire integrity has become an area of concern to the aerospace community including DoD, NASA, FAA, and Industry. Over time and changing environmental conditions, wire insulation can become brittle and crack. The cracks expose the wire conductor and can be a source of equipment failure, short circuits, smoke, and fire. The technique of using the ultrasonic phase spectrum to extract material properties of the insulation is being examined. Ultrasonic guided waves will propagate in both the wire conductor and insulation. Assuming the condition of the conductor remains constant then the stiffness of the insulator can be determined by measuring the ultrasonic guided wave velocity. In the phase spectrum method the guided wave velocity is obtained by transforming the time base waveform to the frequency domain and taking the phase difference between two waveforms. The result can then be correlated with a database, derived by numerical model calculations, to extract material properties of the wire insulator. Initial laboratory tests were performed on a simple model consisting of a solid cylinder and then a solid cylinder with a polymer coating. For each sample the flexural mode waveform was identified. That waveform was then transformed to the frequency domain and a phase spectrum was calculated from a pair of waveforms. Experimental results on the simple model compared well to numerical calculations. Further tests were conducted on aircraft or mil-spec wire samples, to see if changes in wire insulation stiffness can be extracted using the phase spectrum technique.

Radar target classification method with high accuracy and decision speed performance using MUSIC spectrum vectors and PCA projection

NASA Astrophysics Data System (ADS)

Secmen, Mustafa

2011-10-01

This paper introduces the performance of an electromagnetic target recognition method in resonance scattering region, which includes pseudo spectrum Multiple Signal Classification (MUSIC) algorithm and principal component analysis (PCA) technique. The aim of this method is to classify an "unknown" target as one of the "known" targets in an aspect-independent manner. The suggested method initially collects the late-time portion of noise-free time-scattered signals obtained from different reference aspect angles of known targets. Afterward, these signals are used to obtain MUSIC spectrums in real frequency domain having super-resolution ability and noise resistant feature. In the final step, PCA technique is applied to these spectrums in order to reduce dimensionality and obtain only one feature vector per known target. In the decision stage, noise-free or noisy scattered signal of an unknown (test) target from an unknown aspect angle is initially obtained. Subsequently, MUSIC algorithm is processed for this test signal and resulting test vector is compared with feature vectors of known targets one by one. Finally, the highest correlation gives the type of test target. The method is applied to wire models of airplane targets, and it is shown that it can tolerate considerable noise levels although it has a few different reference aspect angles. Besides, the runtime of the method for a test target is sufficiently low, which makes the method suitable for real-time applications.

Dynamic cross correlation studies of wave particle interactions in ULF phenomena

NASA Technical Reports Server (NTRS)

Mcpherron, R. L.

1979-01-01

Magnetic field observations made by satellites in the earth's magnetic field reveal a wide variety of ULF waves. These waves interact with the ambient particle populations in complex ways, causing modulation of the observed particle fluxes. This modulation is found to be a function of species, pitch angle, energy and time. The characteristics of this modulation provide information concerning the wave mode and interaction process. One important characteristic of wave-particle interactions is the phase of the particle flux modulation relative to the magnetic field variations. To display this phase as a function of time a dynamic cross spectrum program has been developed. The program produces contour maps in the frequency time plane of the cross correlation coefficient between any particle flux time series and the magnetic field vector. This program has been utilized in several studies of ULF wave-particle interactions at synchronous orbit.

Characteristic Lifetime Of A Polarized Feature In The V=0, J=1-0 Sio Maser VY Canis Majoris

NASA Astrophysics Data System (ADS)

Rislow, Benjamin; McIntosh, G. C.

2008-05-01

A time series cross correlation analysis has been developed for calculating the characteristic lifetime of linearly polarized features in the spectrum of silicon monoxide masers. Our observations of VY CMa in the v=0, J=1→0; transition from June 2003 to March 2006 revealed a highly linearly polarized feature at Vlsr=18.5 km s-1. Applying the cross correlation to this feature gave a characteristic lifetime of 2800 days. This time is much longer than the v=1, J=2→1; transition's lifetime of 645 days and indicates that the two transitions occur under different physical conditions. This research was supported by the University of Minnesota and the University of Minnesota, Morris.

Cognitive and Neural Correlates of Aging in Autism Spectrum Disorder

DTIC Science & Technology

2016-07-01

1 AWARD NUMBER: W81XWH-15-1-0211 TITLE: "Cognitive and Neural Correlates of Aging in Autism Spectrum Disorder" PRINCIPAL INVESTIGATOR...30 Jun 2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER W81XWH-15-1-0211 XW81XWH-15-1-0211 "Cognitive and Neural Correlates of Aging in Autism ...Scope: This study, which is a collaborative study of the Southwest Autism Research and Resource Center and the Barrow Neurological Institute

Noise produced by turbulent flow into a rotor: Theory manual for noise calculation

NASA Technical Reports Server (NTRS)

Amiet, R. K.

1989-01-01

An analysis is presented for the calculation of noise produced by turbulent flow into a helicopter rotor. The method is based on the analysis of Amiet for the sound produced by an airfoil moving in rectilinear motion through a turbulent flow field. The rectilinear motion results are used in a quasi-steady manner to calculate the instantaneous spectrum of the rotor noise at any given rotor position; the overall spectrum is then found by averaging the instantaneous spectrum over all rotor azimuth angles. Account is taken of the fact that the rotor spends different amounts of retarded time at different rotor positions. Blade to blade correlation is included in the analysis, leading to harmonics of blade passing frequency. The spectrum of the turbulence entering the rotor is calculated by applying rapid distortion theory to an isotropic turbulence spectrum, assuming that the turbulence is stretched as it is pulled into the rotor. The inputs to the program are obtained from the atmospheric turbulence model and mean flow distortion calculation, described in another volume of this set of reports. The analytical basis is provided for a module which was incorporated in NASA's ROTONET helicopter noise prediction program.

Charting the Parameter Space of the 21-cm Power Spectrum

NASA Astrophysics Data System (ADS)

Cohen, Aviad; Fialkov, Anastasia; Barkana, Rennan

2018-05-01

The high-redshift 21-cm signal of neutral hydrogen is expected to be observed within the next decade and will reveal epochs of cosmic evolution that have been previously inaccessible. Due to the lack of observations, many of the astrophysical processes that took place at early times are poorly constrained. In recent work we explored the astrophysical parameter space and the resulting large variety of possible global (sky-averaged) 21-cm signals. Here we extend our analysis to the fluctuations in the 21-cm signal, accounting for those introduced by density and velocity, Lyα radiation, X-ray heating, and ionization. While the radiation sources are usually highlighted, we find that in many cases the density fluctuations play a significant role at intermediate redshifts. Using both the power spectrum and its slope, we show that properties of high-redshift sources can be extracted from the observable features of the fluctuation pattern. For instance, the peak amplitude of ionization fluctuations can be used to estimate whether heating occurred early or late and, in the early case, to also deduce the cosmic mean ionized fraction at that time. The slope of the power spectrum has a more universal redshift evolution than the power spectrum itself and can thus be used more easily as a tracer of high-redshift astrophysics. Its peaks can be used, for example, to estimate the redshift of the Lyα coupling transition and the redshift of the heating transition (and the mean gas temperature at that time). We also show that a tight correlation is predicted between features of the power spectrum and of the global signal, potentially yielding important consistency checks.

Online Epileptic Seizure Prediction Using Wavelet-Based Bi-Phase Correlation of Electrical Signals Tomography.

PubMed

Vahabi, Zahra; Amirfattahi, Rasoul; Shayegh, Farzaneh; Ghassemi, Fahimeh

2015-09-01

Considerable efforts have been made in order to predict seizures. Among these methods, the ones that quantify synchronization between brain areas, are the most important methods. However, to date, a practically acceptable result has not been reported. In this paper, we use a synchronization measurement method that is derived according to the ability of bi-spectrum in determining the nonlinear properties of a system. In this method, first, temporal variation of the bi-spectrum of different channels of electro cardiography (ECoG) signals are obtained via an extended wavelet-based time-frequency analysis method; then, to compare different channels, the bi-phase correlation measure is introduced. Since, in this way, the temporal variation of the amount of nonlinear coupling between brain regions, which have not been considered yet, are taken into account, results are more reliable than the conventional phase-synchronization measures. It is shown that, for 21 patients of FSPEEG database, bi-phase correlation can discriminate the pre-ictal and ictal states, with very low false positive rates (FPRs) (average: 0.078/h) and high sensitivity (100%). However, the proposed seizure predictor still cannot significantly overcome the random predictor for all patients.

Measurements of Impurity Particle Transport Associated with Drift-Wave Turbulence in MST

NASA Astrophysics Data System (ADS)

Nishizawa, Takashi; Nornberg, Mark; Boguski, John; Craig, Darren; den Hartog, Daniel; Pueschel, M. J.; Sarff, John; Terry, Paul; Williams, Zach; Xing, Zichuan

2017-10-01

Understanding and controlling impurity transport in a toroidal magnetized plasma is one of the critical issues that need to be addressed in order to achieve controlled fusion. Gyrokinetic modeling shows turbulence can drive impurity transport, but direct measurements of the turbulent flux have not been made. Particle balance is typically used to infer the presence of turbulent impurity transport. We report, for the first time in a toroidal plasma, direct measurements of turbulence-driven impurity transport. Trapped electron mode (TEM) turbulence appears in MST plasmas when MHD tearing fluctuations are suppressed. Impurity ion-Doppler spectroscopy is used to correlate impurity density and radial velocity fluctuations associated with TEM. Small Doppler shifts associated with the radial velocity fluctuations (rms 1km/s) are resolved with the use of a new linearized spectrum correlation analysis method, which improves the rejection of Poisson noise. The method employs frequency-domain correlation analysis to expose the fluctuation and transport spectrum. The C+ 2 impurity transport velocity driven by turbulence is found to be 48m/s (inward), which is sufficiently large to impact an impurity flux balance in MST improved-confinement plasmas. This work is supported by the US DOE.

Cognitive and Language Correlates of Hyperlexia: Evidence from Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Cardoso-Martins, Claudia; da Silva, Juliane Ribeiro

2010-01-01

Two studies were conducted to investigate the correlates of hyperlexia in Brazilian Portuguese-speaking children with the diagnosis of autism spectrum disorder (ASD). Study 1 involved 3 groups of school age children individually matched for word reading ability: 6 ASD hyperlexic children, 6 ASD non-hyperlexic children, and 6 typically developing…

Eye-Tracking, Autonomic, and Electrophysiological Correlates of Emotional Face Processing in Adolescents with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Wagner, Jennifer B.; Hirsch, Suzanna B.; Vogel-Farley, Vanessa K.; Redcay, Elizabeth; Nelson, Charles A.

2013-01-01

Individuals with autism spectrum disorder (ASD) often have difficulty with social-emotional cues. This study examined the neural, behavioral, and autonomic correlates of emotional face processing in adolescents with ASD and typical development (TD) using eye-tracking and event-related potentials (ERPs) across two different paradigms. Scanning of…

Physical Activity Correlates for Children with Autism Spectrum Disorders in Middle School Physical Education

ERIC Educational Resources Information Center

Pan, Chien-Yu; Tsai, Chia-Liang; Hsieh, Kai-Wen

2011-01-01

This study examined potential correlates that might influence physical activity (PA) of adolescents with autism spectrum disorders (ASD) in physical education. Students with (n = 19) and without (n = 76) ASD wore an accelerometer during physical education. Data were collected in 38 physical education lessons. The results showed that (a) students…

Correlates of Police Involvement among Adolescents and Adults with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Tint, Ami; Palucka, Anna M.; Bradley, Elspeth; Weiss, Jonathan A.; Lunsky, Yona

2017-01-01

This study aimed to describe police interactions, satisfaction with police engagement, as well as examine correlates of police involvement among 284 adolescents and adults with autism spectrum disorder (ASD) followed over a 12- to 18-month period. Approximately 16% of individuals were reported to have some form of police involvement during the…

Sleep Problems and Their Correlates and Comorbid Psychopathology of Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Park, Subin; Cho, Soo-Churl; Cho, In Hee; Kim, Boong-Nyun; Kim, Jae-Won; Shin, Min-Sup; Chung, Un-Sun; Park, Tae-Won; Son, Jung-Woo; Yoo, Hee Jeong

2012-01-01

This study examined sleep problems and their correlates and comorbid psychopathology in children with autism spectrum disorders (ASDs). Participants consisted of 166 ASD children and 111 unaffected siblings aged 4-15 years. Parents completed a self-administered child sleep questionnaire. Of the children with ASDs, 47.0% (78/166) had at least one…

Sleep Disturbances and Correlates of Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Liu, Xianchen; Hubbard, Julie A.; Fabes, Richard A.; Adam, James B.

2006-01-01

This study examined sleep patterns, sleep problems, and their correlates in children with autism spectrum disorders (ASD). Subjects consisted of 167 ASD children, including 108 with autistic disorder, 27 with Asperger's syndrome, and 32 with other diagnoses of ASD. Mean age was 8.8 years (SD = 4.2), 86% were boys. Parents completed a…

Electronic polarization effect on low-frequency infrared and Raman spectra of aprotic solvent: Molecular dynamics simulation study with charge response kernel by second order Møller-Plesset perturbation method

NASA Astrophysics Data System (ADS)

Isegawa, Miho; Kato, Shigeki

2007-12-01

Low-frequency infrared (IR) and depolarized Raman scattering (DRS) spectra of acetonitrile, methylene chloride, and acetone liquids are simulated via molecular dynamics calculations with the charge response kernel (CRK) model obtained at the second order Møller-Plesset perturbation (MP2) level. For this purpose, the analytical second derivative technique for the MP2 energy is employed to evaluate the CRK matrices. The calculated IR spectra reasonably agree with the experiments. In particular, the agreement is excellent for acetone because the present CRK model well reproduces the experimental polarizability in the gas phase. The importance of interaction induced dipole moments in characterizing the spectral shapes is stressed. The DRS spectrum of acetone is mainly discussed because the experimental spectrum is available only for this molecule. The calculated spectrum is close to the experiment. The comparison of the present results with those by the multiple random telegraph model is also made. By decomposing the polarizability anisotropy time correlation function to the contributions from the permanent, induced polarizability and their cross term, a discrepancy from the previous calculations is observed in the sign of permanent-induce cross term contribution. The origin of this discrepancy is discussed by analyzing the correlation functions for acetonitrile.

Can cosmic shear shed light on low cosmic microwave background multipoles?

PubMed

Kesden, Michael; Kamionkowski, Marc; Cooray, Asantha

2003-11-28

The lowest multipole moments of the cosmic microwave background (CMB) are smaller than expected for a scale-invariant power spectrum. One possible explanation is a cutoff in the primordial power spectrum below a comoving scale of k(c) approximately equal to 5.0 x 10(-4) Mpc(-1). Such a cutoff would increase significantly the cross correlation between the large-angle CMB and cosmic-shear patterns. The cross correlation may be detectable at >2sigma which, combined with the low CMB moments, may tilt the balance between a 2sigma result and a firm detection of a large-scale power-spectrum cutoff. The cutoff also increases the large-angle cross correlation between the CMB and the low-redshift tracers of the mass distribution.

Cycles, scaling and crossover phenomenon in length of the day (LOD) time series

NASA Astrophysics Data System (ADS)

Telesca, Luciano

2007-06-01

The dynamics of the temporal fluctuations of the length of the day (LOD) time series from January 1, 1962 to November 2, 2006 were investigated. The power spectrum of the whole time series has revealed annual, semi-annual, decadal and daily oscillatory behaviors, correlated with oceanic-atmospheric processes and interactions. The scaling behavior was analyzed by using the detrended fluctuation analysis (DFA), which has revealed two different scaling regimes, separated by a crossover timescale at approximately 23 days. Flicker-noise process can describe the dynamics of the LOD time regime involving intermediate and long timescales, while Brownian dynamics characterizes the LOD time series for small timescales.

[Study of cholesterol concentration based on serum UV-visible absorption spectrum].

PubMed

Zhu, Wei-Hua; Zhao, Zhi-Min; Guo, Xin; Chen, Hui

2009-04-01

In the present paper, UV-visible absorption spectrum and neural network theory were used for the analysis of cholesterol concentration. Experimental investigation shows that the absorption spectrum has the following characteristics in the wave band of 350-600 nm: (1) There is a stronger absorption peak at 416 nm for the test sample with different cholesterol concentration; (2) There is a shoulder peak between 450 and 500 nm, whose central wavelength is 460 nm; (3) There is a weaker peak at 578 nm; (4) Absorption spectrums shape of different cholesterol concentration is different obviously. The absorption spectrum of serum is the synthesis result of cholesterol and other components (such as sugar), and the information is contained at each wavelength. There is no significant correlation between absorbance and cholesterol content at 416 nm, showing a random relation, so whether cholesterol content is abnormal is not determined by the absorbance peak at 416 nm. Based on the evident correlation between serum absorption spectrum and cholesterol concentration in the wave band of 455-475 nm, a neural network model was built to predict the cholesterol concentration. The correlation coefficient between predicted cholesterol content output A and objectives T reaches 0.968, which can be regarded as better prediction, and it provides a spectra test method of cholesterol concentration.

Combined infrared and ultraviolet-visible spectroscopy matrix-isolated carbon vapor

NASA Technical Reports Server (NTRS)

Kurtz, Joe; Huffman, Donald R.

1990-01-01

Infrared and UV-visible absorption spectra have been measured on the same sample of matrix-isolated carbon vapor in order to establish correlations between absorption intensities of vibrational and electronic transitions as a function of sample annealing. A high degree of correlation has been found between the IR feature at 1998/cm recently assigned to C8 and a UV absorption feature at about 3100 A. Thus, for the first time, direct evidence is given for the assignment of one of the unknown UV-visible features of the long-studied matrix-isolated carbon vapor spectrum.

The Lyman-α power spectrum—CMB lensing convergence cross-correlation

DOE PAGES

Chiang, Chi-Ting; Slosar, Anže

2018-01-11

We investigate the three-point correlation between the Lyman-α forest and the CMB weak lensing (δ Fδ FΚ) expressed as the cross-correlation between the CMB weak lensing field and local variations in the forest power spectrum. In addition to the standard gravitational bispectrum term, we note the existence of a non-standard systematic term coming from mis-estimation of the mean flux over the finite length of Lyman-α skewers. We numerically calculate the angular cross-power spectrum and discuss its features. We integrate it into zero-lag correlation function and compare our predictions with recent results by Doux et al.. We nd that our predictionsmore » are statistically consistent with the measurement, and including the systematic term improves the agreement with the measurement. We comment on the implication of the response of the Lyman-α forest power spectrum to the long-wavelength density perturbations.« less

The Lyman-α power spectrum—CMB lensing convergence cross-correlation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiang, Chi-Ting; Slosar, Anže

We investigate the three-point correlation between the Lyman-α forest and the CMB weak lensing (δ Fδ FΚ) expressed as the cross-correlation between the CMB weak lensing field and local variations in the forest power spectrum. In addition to the standard gravitational bispectrum term, we note the existence of a non-standard systematic term coming from mis-estimation of the mean flux over the finite length of Lyman-α skewers. We numerically calculate the angular cross-power spectrum and discuss its features. We integrate it into zero-lag correlation function and compare our predictions with recent results by Doux et al.. We nd that our predictionsmore » are statistically consistent with the measurement, and including the systematic term improves the agreement with the measurement. We comment on the implication of the response of the Lyman-α forest power spectrum to the long-wavelength density perturbations.« less

Fundamental studies of black chrome for solar collector use

NASA Technical Reports Server (NTRS)

Mcdonald, G.; Buzek, B.; Curtis, H.

1976-01-01

The thicknesses of black chrome plated for various times have been measured from electron photomicrographs and correlated with the solar spectrum absorptance and infrared emittance as calculated from spectral reflectance measurements. The maximum absorptance is reached at an average thickness of 0.5 micrometer. The emittance increases only slightly up to 1.0 micrometer but increases rapidly at thickness above 1.0 micrometer.

Power spectrum, growth velocities and cross-correlations of longitudinal and transverse oscillations of individual Nicotiana tabacum pollen tube.

PubMed

Haduch-Sendecka, Aleksandra; Pietruszka, Mariusz; Zajdel, Paweł

2014-08-01

We report on our results concerning growth rate and oscillation modes of the individual pollen tube apex. The observed volumetric growth and growth rate periodicity in the longitudinal (axial) direction are accompanied by transverse oscillations with similar frequencies but higher energies than the axial modes. Examination of the time-domain coherence between oscillations in mutually perpendicular directions revealed minimal energy dissipation in the unperturbed (isotonic) case, opposite to the two remaining cases (hypertonic, hypotonic) with notable correlations. We conjecture that the minimal energy loss is therefore optimal in the natural growth conditions. The longitudinal growth velocity is also found to be the fastest in the unperturbed case. As a result, the isolated system (pollen tube tip) is conserving energy by transforming it from elastic potential energy of extending apical wall to the kinetic energy of periodical motion. The energy dissipation is found to be about 20 % smaller in axial direction than in lateral one, indicating that the main energy consumption is dedicated to the elongation. We further observe that the hypertonic spectrum is shifted towards lower and the hypotonic towards higher frequencies with respect to the isotonic spectrum. In consequence, the turgor pressure inside the growing cell influences monotonically the frequency of both modes of oscillations. The calculated power spectrum seen as a measure of the overall energy efficiency of tip growth under hypertonic, hypotonic and isotonic conditions implies that the biochemistry has been fine tuned to be optimal under normal growth conditions, which is the developmental implication of this work. A simple theoretical extension of the Ortega equation is derived and analysed with respect to its contribution to power spectrum. We show that the plastic term, related to the effective turgor pressure, with maximum contribution at frequency f = 0 is responsible for the steady growth. In turn, the elastic contribution dependent on the time derivative of pressure fluctuations tends to move the system into oscillatory mode (f > 0). None of those mechanisms is privileged over another. The coupling mechanism is naturally generated through a convolution of those two terms and will decide about the overall character of the growth for each particular case.

Continuous wavelet transform based time-scale and multifractal analysis of the nonlinear oscillations in a hollow cathode glow discharge plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nurujjaman, Md.; Narayanan, Ramesh; Iyengar, A. N. Sekar

2009-10-15

Continuous wavelet transform (CWT) based time-scale and multifractal analyses have been carried out on the anode glow related nonlinear floating potential fluctuations in a hollow cathode glow discharge plasma. CWT has been used to obtain the contour and ridge plots. Scale shift (or inversely frequency shift), which is a typical nonlinear behavior, has been detected from the undulating contours. From the ridge plots, we have identified the presence of nonlinearity and degree of chaoticity. Using the wavelet transform modulus maxima technique we have obtained the multifractal spectrum for the fluctuations at different discharge voltages and the spectrum was observed tomore » become a monofractal for periodic signals. These multifractal spectra were also used to estimate different quantities such as the correlation and fractal dimension, degree of multifractality, and complexity parameters. These estimations have been found to be consistent with the nonlinear time series analysis.« less

Multifractal detrended cross-correlation analysis in the MENA area

NASA Astrophysics Data System (ADS)

El Alaoui, Marwane; Benbachir, Saâd

2013-12-01

In this paper, we investigated multifractal cross-correlations qualitatively and quantitatively using a cross-correlation test and the Multifractal detrended cross-correlation analysis method (MF-DCCA) for markets in the MENA area. We used cross-correlation coefficients to measure the level of this correlation. The analysis concerns four stock market indices of Morocco, Tunisia, Egypt and Jordan. The countries chosen are signatory of the Agadir agreement concerning the establishment of a free trade area comprising Arab Mediterranean countries. We computed the bivariate generalized Hurst exponent, Rényi exponent and spectrum of singularity for each pair of indices to measure quantitatively the cross-correlations. By analyzing the results, we found the existence of multifractal cross-correlations between all of these markets. We compared the spectrum width of these indices; we also found which pair of indices has a strong multifractal cross-correlation.

Power spectrum entropy of acceleration time-series during movement as an indicator of smoothness of movement.

PubMed

Kojima, Motonaga; Obuchi, Shuichi; Mizuno, Kousuke; Henmi, Osamu; Ikeda, Noriaki

2008-06-01

We propose a novel indicator for smoothness of movement, i.e., the power spectrum entropy of the acceleration time-series, and compare it with conventional indices of smoothness. For this purpose, nineteen healthy adults (21.3+/-2.5 years old) performed the task of raising and lowering a beaker between the level of the umbilicus and eye level under the two following conditions: one with the beaker containing water and the other with the beaker containing a weight of the same mass as the water. Moving the beaker up and down when it contained water required extra control to prevent the water from being spilled. This means that movement was not as smooth as when the beaker contained a weight. Under these two conditions, entropy was measured along with a traditional indicator of smoothness of movement, the jerk index. The entropy could distinguish just as well as the jerk index (p<0.01) between when water was used and when the weight was used. The entropy correlated highly with the jerk index, with Spearman's rho at 0.88 (p<0.01). These results showed that the entropy derived from the spectrum of the acceleration time-series during movement is useful as an indicator of the smoothness of that movement.

Coincidence electron/ion imaging with a fast frame camera

NASA Astrophysics Data System (ADS)

Li, Wen; Lee, Suk Kyoung; Lin, Yun Fei; Lingenfelter, Steven; Winney, Alexander; Fan, Lin

2015-05-01

A new time- and position- sensitive particle detection system based on a fast frame CMOS camera is developed for coincidence electron/ion imaging. The system is composed of three major components: a conventional microchannel plate (MCP)/phosphor screen electron/ion imager, a fast frame CMOS camera and a high-speed digitizer. The system collects the positional information of ions/electrons from a fast frame camera through real-time centroiding while the arrival times are obtained from the timing signal of MCPs processed by a high-speed digitizer. Multi-hit capability is achieved by correlating the intensity of electron/ion spots on each camera frame with the peak heights on the corresponding time-of-flight spectrum. Efficient computer algorithms are developed to process camera frames and digitizer traces in real-time at 1 kHz laser repetition rate. We demonstrate the capability of this system by detecting a momentum-matched co-fragments pair (methyl and iodine cations) produced from strong field dissociative double ionization of methyl iodide. We further show that a time resolution of 30 ps can be achieved when measuring electron TOF spectrum and this enables the new system to achieve a good energy resolution along the TOF axis.

Self-interaction-corrected time-dependent density-functional-theory calculations of x-ray-absorption spectra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tu, Guangde; Rinkevicius, Zilvinas; Vahtras, Olav

We outline an approach within time-dependent density functional theory that predicts x-ray spectra on an absolute scale. The approach rests on a recent formulation of the resonant-convergent first-order polarization propagator [P. Norman et al., J. Chem. Phys. 123, 194103 (2005)] and corrects for the self-interaction energy of the core orbital. This polarization propagator approach makes it possible to directly calculate the x-ray absorption cross section at a particular frequency without explicitly addressing the excited-state spectrum. The self-interaction correction for the employed density functional accounts for an energy shift of the spectrum, and fully correlated absolute-scale x-ray spectra are thereby obtainedmore » based solely on optimization of the electronic ground state. The procedure is benchmarked against experimental spectra of a set of small organic molecules at the carbon, nitrogen, and oxygen K edges.« less

The relationship between waiting times and 'adherence' to the Scottish Intercollegiate Guidelines Network 98 guideline in autism spectrum disorder diagnostic services in Scotland.

PubMed

McKenzie, Karen; Forsyth, Kirsty; O'Hare, Anne; McClure, Iain; Rutherford, Marion; Murray, Aja; Irvine, Linda

2016-05-01

The aim of this study was to explore the extent to which the Scottish Intercollegiate Guidelines Network 98 guidelines on the assessment and diagnosis of autism spectrum disorder were adhered to in child autism spectrum disorder diagnostic services in Scotland and whether there was a significant relationship between routine practice which more closely reflected these recommendations (increased adherence) and increased waiting times. Retrospective, cross-sectional case note analysis was applied to data from 80 case notes. Adherence ranged from a possible 0 (no adherence) to 19 (full adherence). Overall, 17/22 of the recommendations were adhered to in over 50 of the 80 cases and in 70 or more cases for 11/22 of the recommendations, with a mean adherence score of 16 (standard deviation = 1.9). No significant correlation was found between adherence and total wait time for untransformed (r = 0.15, p = 0.32) or transformed data (r = 0.12, p = 0.20). The results indicated that the assessment and diagnostic practices were consistent with the relevant Scottish Intercollegiate Guidelines Network 98 guideline recommendations. Increased adherence to the 19 included recommendations was not significantly related to increased total waiting times, indicating that the Scottish Intercollegiate Guidelines Network 98 recommendations have generally been integrated into practice, without a resultant increase in patient waits. © The Author(s) 2015.

Variations of the TeV energy spectrum at different flux levels of Mkn 421 observed with the HEGRA system of Cherenkov telescopes

NASA Astrophysics Data System (ADS)

Aharonian, F.; Akhperjanian, A.; Beilicke, M.; Bernlöhr, K.; Börst, H.; Bojahr, H.; Bolz, O.; Coarasa, T.; Contreras, J.; Cortina, J.; Costamante, L.; Denninghoff, S.; Fonseca, V.; Girma, M.; Götting, N.; Heinzelmann, G.; Hermann, G.; Heusler, A.; Hofmann, W.; Horns, D.; Jung, I.; Kankanyan, R.; Kestel, M.; Kettler, J.; Kohnle, A.; Konopelko, A.; Kornmeyer, H.; Kranich, D.; Krawczynski, H.; Lampeitl, H.; Lopez, M.; Lorenz, E.; Lucarelli, F.; Mang, O.; Meyer, H.; Mirzoyan, R.; Milite, M.; Moralejo, A.; Ona, E.; Panter, M.; Plyasheshnikov, A.; Pühlhofer, G.; Rauterberg, G.; Reyes, R.; Rhode, W.; Ripken, J.; Rowell, G.; Sahakian, V.; Samorski, M.; Schilling, M.; Siems, M.; Sobzynska, D.; Stamm, W.; Tluczykont, M.; Völk, H. J.; Wiedner, C. A.; Wittek, W.; Remillard, R. A.

2002-10-01

The nearby BL Lacertae (BL Lac) object Markarian 421 (Mkn 421) at a red shift z=0.031 was observed to undergo strong TeV gamma -ray outbursts in the observational periods from December 1999 until May 2001. The time averaged flux level F(E>1 TeV) in the 1999/2000 season was (1.43+/-0.04) x 10-11 ph cm-2 s-1, whereas in the 2000/2001 season the average integral flux increased to (4.19+/-0.04) x 10-11 ph cm-2 s-1. Both energy spectra are curved and well fit by a power law with an exponential cut-off energy at 3.6(+0.4-0.3)_stat(+0.9-0.8)_sys TeV. The respective energy spectra averaged over each of the two time periods indicate a spectral hardening for the 2000/2001 spectrum. The photon index changes from 2.39+/-0.09_stat for 1999/2000 to 2.19+/-0.02_stat in 2000/2001. The energy spectra derived for different average flux levels ranging from 0.5 to 10 x 10-11 ph cm-2 s-1 follow a clear correlation of photon index and flux level. Generally, the energy spectra are harder for high flux levels. From January to April 2001 Mkn 421 showed rapid variability (doubling time as short as 20 min), accompanied with a spectral hardening with increasing flux level within individual nights. For two successive nights (MJD 51989-51991, March 21-23, 2001), this correlation of spectral hardness and change in flux has been observed within a few hours. The cut-off energy for the Mkn 421 TeV spectrum remains within the errors constant for the different flux levels and differs by Delta E=2.6+/-0.6_stat+/-0.6_sys TeV from the value determined for Mkn 501. This indicates that the observed exponential cut-off in the energy spectrum of Mkn 421 is not solely caused by absorption of multi-TeV photons by pair-production processes with photons of the extragalactic near/mid infrared background radiation.

Characterizing Sky Spectra Using SDSS BOSS Data

NASA Astrophysics Data System (ADS)

Florez, Lina Maria; Strauss, Michael A.

2018-01-01

In the optical/near-infrared spectra gathered by a ground-based telescope observing very faint sources, the strengths of the emission lines due to the Earth’s atmosphere can be many times larger than the fluxes of the sources we are interested in. Thus the limiting factor in faint-object spectroscopy is the degree to which systematics in the sky subtraction can be minimized. Longwards of 6000 Angstroms, the night-sky spectrum is dominated by multiple vibrational/rotational transitions of the OH radical from our upper atmosphere. While the wavelengths of these lines are the same in each sky spectrum, their relative strengths vary considerably as a function of time and position on the sky. The better we can model their strengths, the better we can hope to subtract them off. We expect that the strength of lines from common upper energy levels will be correlated with one another. We used flux-calibrated sky spectra from the Sloan Digital Sky Survey Baryon Oscillation Spectroscopic Survey (SDSS BOSS) to explore these correlations. Our aim is to use these correlations for creating improved sky subtraction algorithms for the Prime Focus Spectrograph (PFS) on the 8.2-meter Subaru Telescope. When PFS starts gathering data in 2019, it will be the most powerful multi-object spectrograph in the world. Since PFS will be gathering data on sources as faint as 24th magnitude and fainter, it's of upmost importance to be able to accurately measure and subtract sky spectra from the data that we receive.

Imprints of spherical nontrivial topologies on the cosmic microwave background.

PubMed

Niarchou, Anastasia; Jaffe, Andrew

2007-08-24

The apparent low power in the cosmic microwave background (CMB) temperature anisotropy power spectrum derived from the Wilkinson Microwave Anisotropy Probe motivated us to consider the possibility of a nontrivial topology. We focus on simple spherical multiconnected manifolds and discuss their implications for the CMB in terms of the power spectrum, maps, and the correlation matrix. We perform a Bayesian model comparison against the fiducial best-fit cold dark matter model with a cosmological constant based both on the power spectrum and the correlation matrix to assess their statistical significance. We find that the first-year power spectrum shows a slight preference for the truncated cube space, but the three-year data show no evidence for any of these spaces.

Trajectories and Correlates of Special Education Supports for Youth with Autism Spectrum Disorder and Psychiatric Comparisons

ERIC Educational Resources Information Center

Spaulding, Christine J.; Lerner, Matthew D.; Gadow, Kenneth D.

2017-01-01

Relatively little is known about patterns of school-based supportive services for youth with autism spectrum disorder. This study describes these supportive services and their correlates, both cross-sectionally and retrospectively, in a large sample (N = 283) of 6- to 18-year-old youth. To assess whether special education designation and classroom…

The Prevalence and Psychopathological Correlates of Sibling Bullying in Children with and without Autism Spectrum Disorder

ERIC Educational Resources Information Center

Toseeb, Umar; McChesney, Gillian; Wolke, Dieter

2018-01-01

Using data from a prospective population based study, the prevalence and psychopathological correlates of sibling bullying in children with and without autism spectrum disorder (ASD) were estimated. There were 475 children with ASD and 13,702 children without ASD aged 11 years. Children with ASD were more likely to be bullied by their siblings…

Profiles and Correlates of Parent-Child Agreement on Social Anxiety Symptoms in Youth with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Burrows, Catherine A.; Usher, Lauren V.; Becker-Haimes, Emily M.; McMahon, Camilla M.; Mundy, Peter C.; Jensen-Doss, Amanda; Henderson, Heather A.

2018-01-01

This study characterized patterns and correlates of parent-youth agreement on social anxiety in youth with and without autism spectrum disorder (ASD). Participants (279 verbally-fluent youth aged 8-16 years, NASD = 144, NTD = 135) completed the SASC-R. Youth with ASD exhibited higher social anxiety across informants. While TD youth endorsed higher…

The rank correlated FSK model for prediction of gas radiation in non-uniform media, and its relationship to the rank correlated SLW model

NASA Astrophysics Data System (ADS)

Solovjov, Vladimir P.; Webb, Brent W.; Andre, Frederic

2018-07-01

Following previous theoretical development based on the assumption of a rank correlated spectrum, the Rank Correlated Full Spectrum k-distribution (RC-FSK) method is proposed. The method proves advantageous in modeling radiation transfer in high temperature gases in non-uniform media in two important ways. First, and perhaps most importantly, the method requires no specification of a reference gas thermodynamic state. Second, the spectral construction of the RC-FSK model is simpler than original correlated FSK models, requiring only two cumulative k-distributions. Further, although not exhaustive, example problems presented here suggest that the method may also yield improved accuracy relative to prior methods, and may exhibit less sensitivity to the blackbody source temperature used in the model predictions. This paper outlines the theoretical development of the RC-FSK method, comparing the spectral construction with prior correlated spectrum FSK method formulations. Further the RC-FSK model's relationship to the Rank Correlated Spectral Line Weighted-sum-of-gray-gases (RC-SLW) model is defined. The work presents predictions using the Rank Correlated FSK method and previous FSK methods in three different example problems. Line-by-line benchmark predictions are used to assess the accuracy.

Determination of melamine of milk based on two-dimensional correlation infrared spectroscopy

NASA Astrophysics Data System (ADS)

Yang, Ren-jie; Liu, Rong; Xu, Kexin

2012-03-01

The adulteration of milk with harmful substances is a threat to public health and beyond question a serious crime. In order to develop a rapid, cost-effective, high-throughput analysis method for detecting of adulterants in milk, the discriminative analysis of melamine is established in milk based on the two-dimensional (2D) correlation infrared spectroscopy in present paper. Pure milk samples and adulterated milk samples with different content of melamine were prepared. Then the Fourier Transform Infrared spectra of all samples were measured at room temperature. The characteristics of pure milk and adulterated milk were studied by one-dimensional spectra. The 2D NIR and 2D IR correlation spectroscopy were calculated under the perturbation of adulteration concentration. In the range from 1400 to 1800 cm-1, two strong autopeaks were aroused by melamine in milk at 1464 cm-1 and 1560 cm-1 in synchronous spectrum. At the same time, the 1560 cm-1 band does not share cross peak with the 1464 cm-1 band, which further confirm that the two bands have the same origin. Also in the range from 4200 to 4800 cm-1, the autopeak was shown at 4648 cm-1 in synchronous spectrum of melamine in milk. 2D NIR-IR hetero-spectral correlation analysis confirmed that the bands at 1464, 1560 and 4648 cm-1 had the same origin. The results demonstrated that the adulterant can be discriminated correctly by 2D correlation infrared spectroscopy.

Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

NASA Astrophysics Data System (ADS)

Li, Tanping; Cui, Yaowen; Mathaga, John; Kumar, Revati; Kuroda, Daniel G.

2015-06-01

Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm-1 region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ˜0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters.

Hydration and vibrational dynamics of betaine (N,N,N-trimethylglycine)

PubMed Central

Li, Tanping; Cui, Yaowen; Mathaga, John; Kumar, Revati; Kuroda, Daniel G.

2015-01-01

Zwitterions are naturally occurring molecules that have a positive and a negative charge group in its structure and are of great importance in many areas of science. Here, the vibrational and hydration dynamics of the zwitterionic system betaine (N,N,N-trimethylglycine) is reported. The linear infrared spectrum of aqueous betaine exhibits an asymmetric band in the 1550-1700 cm−1 region of the spectrum. This band is attributed to the carboxylate asymmetric stretch of betaine. The potential of mean force computed from ab initio molecular dynamic simulations confirms that the two observed transitions of the linear spectrum are related to two different betaine conformers present in solution. A model of the experimental data using non-linear response theory agrees very well with a vibrational model comprising of two vibrational transitions. In addition, our modeling shows that spectral parameters such as the slope of the zeroth contour plot and central line slope are both sensitive to the presence of overlapping transitions. The vibrational dynamics of the system reveals an ultrafast decay of the vibrational population relaxation as well as the correlation of frequency-frequency correlation function (FFCF). A decay of ∼0.5 ps is observed for the FFCF correlation time and is attributed to the frequency fluctuations caused by the motions of water molecules in the solvation shell. The comparison of the experimental observations with simulations of the FFCF from ab initio molecular dynamics and a density functional theory frequency map shows a very good agreement corroborating the correct characterization and assignment of the derived parameters. PMID:26049458

Magnetic resonance imaging (MRI) and relaxation spectrum analysis as methods to investigate swelling in whey protein gels.

PubMed

Oztop, Mecit H; Rosenberg, Moshe; Rosenberg, Yael; McCarthy, Kathryn L; McCarthy, Michael J

2010-10-01

Effective means for controlled delivery of nutrients and nutraceuticals are needed. Whey protein-based gels, as a model system and as a potential delivery system, exhibit pH-dependent swelling when placed in aqueous solutions. Understanding the physics that govern gel swelling is thus important when designing gel-based delivery platforms. The extent of swelling over time was monitored gravimetrically. In addition to gravimetric measurements, magnetic resonance imaging (MRI) a real-time noninvasive imaging technique that quantified changes in geometry and water content of these gels was utilized. Heat-set whey protein gels were prepared at pH 7 and swelling was monitored in aqueous solutions with pH values of 2.5, 7, and 10. Changes in dimension over time, as characterized by the number of voxels in an image, were correlated to gravimetric measurements. Excellent correlations between mass uptake and volume change (R(2)= 0.99) were obtained for the gels in aqueous solutions at pH 7 and 10, but not for gels in the aqueous solution at pH 2.5. To provide insight into the mechanisms for water uptake, nuclear magnetic resonance (NMR) relaxation times were measured in independent experiments. The relaxation spectrum for the spin-spin relaxation time (T(2)) showed the presence of 3 proton pools for pH 7 and 10 trials and 4 proton pools for pH 2.5 trials. Results demonstrate that MRI and NMR relaxation measurements provided information about swelling in whey protein gels that can constitute a new means for investigating and developing effective delivery systems for foods.

Discovery of X-Ray Emission from the Galactic Supernova Remnant G32.8-0.1 with Suzaku

NASA Technical Reports Server (NTRS)

Bamba, Aya; Terada, Yukikatsu; Hewitt, John; Petre, Robert; Angelini, Lorella; Safi-Harb, Samar; Zhou, Ping; Bocchino, Fabrizio; Sawada, Makoto

2016-01-01

We present the first dedicated X-ray study of the supernova remnant (SNR) G32.8-0.1 (Kes 78) with Suzaku. X-ray emission from the whole SNR shell has been detected for the first time. The X-ray morphology is well correlated with the emission from the radio shell, while anti-correlated with the molecular cloud found in the SNR field. The X-ray spectrum shows not only conventional low-temperature (kT approximately 0.6 kiloelectronvolts) thermal emission in a nonequilibrium ionization state, but also a very high-temperature (approximately 3.4 kiloelectronvolts) component with a very low ionization timescale (approximately 2.7 times 10 (sup 9) per cubic centimeter per second), or a hard nonthermal component with a photon index Gamma approximately equal to 2.3. The average density of the low-temperature plasma is rather low, of the order of 10 (sup -3) - 10 (sup -2) per cubic centimeter, implying that this SNR is expanding into a low-density cavity. We discuss the X-ray emission of the SNR, also detected in teraelectronvolts with H.E.S.S. (High Energy Stereoscopic System), together with multi-wavelength studies of the remnant and other gamma-ray emitting SNRs, such as W28 and RCW 86. Analysis of a time-variable source, 2XMM J185114.3-000004, found in the northern part of the SNR, is also reported for the first time. Rapid time variability and a heavily absorbed hard-X-ray spectrum suggest that this source could be a new supergiant fast X-ray transient.

Meta-analysis of Big Five personality traits in autism spectrum disorder.

PubMed

Lodi-Smith, Jennifer; Rodgers, Jonathan D; Cunningham, Sara A; Lopata, Christopher; Thomeer, Marcus L

2018-04-01

The present meta-analysis synthesizes the emerging literature on the relationship of Big Five personality traits to autism spectrum disorder. Studies were included if they (1) either (a) measured autism spectrum disorder characteristics using a metric that yielded a single score quantification of the magnitude of autism spectrum disorder characteristics and/or (b) studied individuals with an autism spectrum disorder diagnosis compared to individuals without an autism spectrum disorder diagnosis and (2) measured Big Five traits in the same sample or samples. Fourteen reviewed studies include both correlational analyses and group comparisons. Eighteen effect sizes per Big Five trait were used to calculate two overall effect sizes per trait. Meta-analytic effects were calculated using random effects models. Twelve effects (per trait) from nine studies reporting correlations yielded a negative association between each Big Five personality trait and autism spectrum disorder characteristics (Fisher's z ranged from -.21 (conscientiousness) to -.50 (extraversion)). Six group contrasts (per trait) from six studies comparing individuals diagnosed with autism spectrum disorder to neurotypical individuals were also substantial (Hedges' g ranged from -.88 (conscientiousness) to -1.42 (extraversion)). The potential impact of personality on important life outcomes and new directions for future research on personality in autism spectrum disorder are discussed in light of results.

Two-point correlators revisited: fast and slow scales in multifield models of inflation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghersi, José T. Gálvez; Frolov, Andrei V., E-mail: joseg@sfu.ca, E-mail: frolov@sfu.ca

2017-05-01

We study the structure of two-point correlators of the inflationary field fluctuations in order to improve the accuracy and efficiency of the existing methods to calculate primordial spectra. We present a description motivated by the separation of the fast and slow evolving components of the spectrum which is based on Cholesky decomposition of the field correlator matrix. Our purpose is to rewrite all the relevant equations of motion in terms of slowly varying quantities. This is important in order to consider the contribution from high-frequency modes to the spectrum without affecting computational performance. The slow-roll approximation is not required tomore » reproduce the main distinctive features in the power spectrum for each specific model of inflation.« less

Asperger syndrome in males over two decades: Quality of life in relation to diagnostic stability and psychiatric comorbidity.

PubMed

Helles, Adam; Gillberg, I Carina; Gillberg, Christopher; Billstedt, Eva

2017-05-01

This study examined objective quality of life (work, academic success, living situation, relationships, support system) and subjective quality of life (Sense of Coherence and Short-Form Health Survey-36) in an adult sample of males ( n = 50, mean age: 30 years) with Asperger syndrome diagnosed in childhood and followed prospectively over two decades. The association between long-term diagnostic stability of an autism spectrum disorder and/or comorbid psychiatric disorders with quality of life was also examined. The results showed great variability as regards quality of life. The subsample that no longer fulfilled an autism spectrum disorder had full-time jobs or studies (10/11), independent living (100%), and reported having two or more friends (100%). In the stable autism spectrum disorder group, 41% had full-time job or studies, 51% lived independently, and 33% reported two or more friends, and a significant minority had specialized employments, lived with support from the government, or had no friends. Academic success was positively correlated with IQ. A majority of the total group scored average Sense of Coherence scores, and the mean for Short-Form Health Survey-36 was above average regarding psychical health and below average regarding mental health. Stability of autism spectrum disorder diagnosis was associated with objective but not subjective quality of life, while psychiatric comorbidity was associated with subjective but not objective quality of life.

A luminous hot accretion flow in the low-luminosity active galactic nucleus NGC 7213

NASA Astrophysics Data System (ADS)

Xie, Fu-Guo; Zdziarski, Andrzej A.; Ma, Renyi; Yang, Qi-Xiang

2016-12-01

The active galactic nucleus (AGN) NGC 7213 shows a complex correlation between the monochromatic radio luminosity LR and the 2-10 keV X-ray luminosity LX, I.e. the correlation is unusually weak with p ˜ 0 (in the form L_R∝ L_X^p) when LX is below a critical luminosity, and steep with p > 1 when LX is above that luminosity. Such a hybrid correlation in individual AGNs is unexpected as it deviates from the Fundamental Plane of AGN activity. Interestingly, a similar correlation pattern is observed in the black hole X-ray binary H1743-322, where it has been modelled by switching between different modes of accretion. We propose that the flat LR-LX correlation of NGC 7213 is due to the presence of a luminous hot accretion flow, an accretion model whose radiative efficiency is sensitive to the accretion rate. Given the low luminosity of the source, LX ˜ 10-4 of the Eddington luminosity, the viscosity parameter is determined to be small, α ≈ 0.01. We also modelled the broad-band spectrum from radio to γ-rays, the time lag between the radio and X-ray light curves, and the implied size and the Lorentz factor of the radio jet. We predict that NGC 7213 will enter into a two-phase accretion regime when LX ≳ 1.5 × 1042 erg s- 1. When this happens, we predict a softening of the X-ray spectrum with the increasing flux and a steep radio/X-ray correlation.

QUIET-TIME SUPRATHERMAL (∼0.1–1.5 keV) ELECTRONS IN THE SOLAR WIND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tao, Jiawei; Wang, Linghua; Zong, Qiugang

2016-03-20

We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1–1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ∼0.1–1.5 keV to a Kappa distribution function with an index κ and effective temperature T{sub eff}. We also calculate the number density n and average energy E{sub avg} of strahl andmore » halo electrons by integrating the electron measurements between ∼0.1 and 1.5 keV. We find a strong positive correlation between κ and T{sub eff} for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity)« less

Statistical Significance of Periodicity and Log-Periodicity with Heavy-Tailed Correlated Noise

NASA Astrophysics Data System (ADS)

Zhou, Wei-Xing; Sornette, Didier

We estimate the probability that random noise, of several plausible standard distributions, creates a false alarm that a periodicity (or log-periodicity) is found in a time series. The solution of this problem is already known for independent Gaussian distributed noise. We investigate more general situations with non-Gaussian correlated noises and present synthetic tests on the detectability and statistical significance of periodic components. A periodic component of a time series is usually detected by some sort of Fourier analysis. Here, we use the Lomb periodogram analysis, which is suitable and outperforms Fourier transforms for unevenly sampled time series. We examine the false-alarm probability of the largest spectral peak of the Lomb periodogram in the presence of power-law distributed noises, of short-range and of long-range fractional-Gaussian noises. Increasing heavy-tailness (respectively correlations describing persistence) tends to decrease (respectively increase) the false-alarm probability of finding a large spurious Lomb peak. Increasing anti-persistence tends to decrease the false-alarm probability. We also study the interplay between heavy-tailness and long-range correlations. In order to fully determine if a Lomb peak signals a genuine rather than a spurious periodicity, one should in principle characterize the Lomb peak height, its width and its relations to other peaks in the complete spectrum. As a step towards this full characterization, we construct the joint-distribution of the frequency position (relative to other peaks) and of the height of the highest peak of the power spectrum. We also provide the distributions of the ratio of the highest Lomb peak to the second highest one. Using the insight obtained by the present statistical study, we re-examine previously reported claims of ``log-periodicity'' and find that the credibility for log-periodicity in 2D-freely decaying turbulence is weakened while it is strengthened for fracture, for the ion-signature prior to the Kobe earthquake and for financial markets.

Boson peak dynamics of natural polymer starch investigated by terahertz time-domain spectroscopy and low-frequency Raman scattering.

PubMed

Terao, Wakana; Mori, Tatsuya; Fujii, Yasuhiro; Koreeda, Akitoshi; Kabeya, Mikitoshi; Kojima, Seiji

2018-03-05

Terahertz time-domain spectroscopy and low-frequency Raman scattering were performed on the natural polymer starch to investigate the boson peak (BP) dynamics. In the infrared spectrum, the BP was observed at 0.99THz at the lowest temperature. Compared to the result from a previous study for vitreous glucose, both the frequency of the BP and absorption coefficient show lower values than those of the vitreous glucose. These behaviors originate from the longer correlation length of the medium-range order and lower concentration of hydroxyl groups in the starch. In the Raman spectrum, the BP was observed at 1.1THz at room temperature, although the BP was not observed around room temperature due to the excess wing of the fast relaxation modes in the infrared spectrum. The temperature dependence of ε″(ν) during the heating process and cooling process shows a hysteresis below 230K. During the heating process, kinks were observed at 140K and 230K. These kinks are attributed to the β-relaxation and the β wet -relaxation, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Effective theory of dark energy at redshift survey scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gleyzes, Jérôme; Mancarella, Michele; Vernizzi, Filippo

2016-02-01

We explore the phenomenological consequences of general late-time modifications of gravity in the quasi-static approximation, in the case where cold dark matter is non-minimally coupled to the gravitational sector. Assuming spectroscopic and photometric surveys with configuration parameters similar to those of the Euclid mission, we derive constraints on our effective description from three observables: the galaxy power spectrum in redshift space, tomographic weak-lensing shear power spectrum and the correlation spectrum between the integrated Sachs-Wolfe effect and the galaxy distribution. In particular, with ΛCDM as fiducial model and a specific choice for the time dependence of our effective functions, we performmore » a Fisher matrix analysis and find that the unmarginalized 68% CL errors on the parameters describing the modifications of gravity are of order σ∼10{sup −2}–10{sup −3}. We also consider two other fiducial models. A nonminimal coupling of CDM enhances the effects of modified gravity and reduces the above statistical errors accordingly. In all cases, we find that the parameters are highly degenerate, which prevents the inversion of the Fisher matrices. Some of these degeneracies can be broken by combining all three observational probes.« less

Development of a High Resolution X-ray Spectrometer on the National Ignition Facility

NASA Astrophysics Data System (ADS)

Gao, L.; Kraus, B.; Hill, K. W.; Bitter, M.; Efthimion, P.; Schneider, M. B.; Chen, H.; Ayers, J.; Liedahl, D.; Macphee, A. G.; Le, H. P.; Thorn, D.; Nelson, D.

2017-10-01

A high-resolution x-ray spectrometer has been designed, calibrated, and deployed on the National Ignition Facility (NIF) to measure plasma parameters for a Kr-doped surrogate capsule imploded at NIF conditions. Two conical crystals, each diffracting the He α and He β complexes respectively, focus the spectra onto a steak camera photocathode for time-resolved measurements with a temporal resolution of <20 ps. A third cylindrical crystal focuses the entire He α to He β spectrum onto an image plate for a time-integrated spectrum to correlate the two streaked signals. The instrument was absolutely calibrated by the x-ray group at the Princeton Plasma Physics Laboratory using a micro-focus x-ray source. Detailed calibration procedures, including source and spectrum alignment, energy calibration, crystal performance evaluation, and measurement of the resolving power and the integrated reflectivity will be presented. Initial NIF experimental results will also be discussed. This work was performed under the auspices of the U.S. Department of Energy by Princeton Plasma Physics Laboratory under contract DE-AC02-09CH11466 and by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344.

The Stability and Validity of Automated Vocal Analysis in Preverbal Preschoolers With Autism Spectrum Disorder

PubMed Central

Woynaroski, Tiffany; Oller, D. Kimbrough; Keceli-Kaysili, Bahar; Xu, Dongxin; Richards, Jeffrey A.; Gilkerson, Jill; Gray, Sharmistha; Yoder, Paul

2017-01-01

Theory and research suggest that vocal development predicts “useful speech” in preschoolers with autism spectrum disorder (ASD), but conventional methods for measurement of vocal development are costly and time consuming. This longitudinal correlational study examines the reliability and validity of several automated indices of vocalization development relative to an index derived from human coded, conventional communication samples in a sample of preverbal preschoolers with ASD. Automated indices of vocal development were derived using software that is presently “in development” and/or only available for research purposes and using commercially available Language ENvironment Analysis (LENA) software. Indices of vocal development that could be derived using the software available for research purposes: (a) were highly stable with a single day-long audio recording, (b) predicted future spoken vocabulary to a degree that was nonsignificantly different from the index derived from conventional communication samples, and (c) continued to predict future spoken vocabulary even after controlling for concurrent vocabulary in our sample. The score derived from standard LENA software was similarly stable, but was not significantly correlated with future spoken vocabulary. Findings suggest that automated vocal analysis is a valid and reliable alternative to time intensive and expensive conventional communication samples for measurement of vocal development of preverbal preschoolers with ASD in research and clinical practice. PMID:27459107

Sparsely sampling the sky: Regular vs. random sampling

NASA Astrophysics Data System (ADS)

Paykari, P.; Pires, S.; Starck, J.-L.; Jaffe, A. H.

2015-09-01

Aims: The next generation of galaxy surveys, aiming to observe millions of galaxies, are expensive both in time and money. This raises questions regarding the optimal investment of this time and money for future surveys. In a previous work, we have shown that a sparse sampling strategy could be a powerful substitute for the - usually favoured - contiguous observation of the sky. In our previous paper, regular sparse sampling was investigated, where the sparse observed patches were regularly distributed on the sky. The regularity of the mask introduces a periodic pattern in the window function, which induces periodic correlations at specific scales. Methods: In this paper, we use a Bayesian experimental design to investigate a "random" sparse sampling approach, where the observed patches are randomly distributed over the total sparsely sampled area. Results: We find that in this setting, the induced correlation is evenly distributed amongst all scales as there is no preferred scale in the window function. Conclusions: This is desirable when we are interested in any specific scale in the galaxy power spectrum, such as the matter-radiation equality scale. As the figure of merit shows, however, there is no preference between regular and random sampling to constrain the overall galaxy power spectrum and the cosmological parameters.

Magnetization hysteresis electron paramagnetic resonance. A new null phase insensitive saturation transfer EPR technique with high sensitivity to slow motion.

PubMed Central

Vistnes, A I

1983-01-01

In electron paramagnetic resonance (EPR) nonlinear phenomena with respect to magnetic-field modulation are often studied by out-of-phase spectra recordings. The existence of a nonzero out-of-phase signal implies that the EPR signal is phase shifted relative to the modulation signal. This phase shift is called a magnetization hysteresis. The hysteresis angle varies during a sweep through the resonance conditions for a free radical. By recording this variation, a magnetization hysteresis (MH) spectrum results. In practice, a MH spectrum is computer calculated from two EPR spectra detected with a 90 degree difference in phase setting. There is no need for a careful null-phase calibration like that in traditional analysis of nonlinearities. The MH spectra calculated from second harmonic EPR spectra of spin labels were highly dependent on the rotational correlation time. The technique can therefore be used to study slow molecular motion. In the present work MH spectra and Hemminga and deJager's magnitude saturation transfer EPR spectra (Hemminga, M. A., and P. A. deJager, 1981, J. Magn. Reson., 43:324-327) have been analyzed to define parameters that can describe variations in the rotational correlation time. A novel modification of the sample holder and temperature regulation equipment is described. PMID:6309263

Divergent Thinking Abilities across the Schizophrenic Spectrum and Other Psychological Correlates

ERIC Educational Resources Information Center

Rodrigue, Amanda L.; Perkins, David R.

2012-01-01

The literature on the connection between psychopathology and creativity is vast and recent research has focused on the relationship between the schizophrenic spectrum and creativity. The schizophrenic spectrum includes genetically related disorders that share certain symptom features. It has been suggested that schizotypal personality disorder, a…

Deterministic filtering of breakdown flashing at telecom wavelengths

NASA Astrophysics Data System (ADS)

Marini, Loris; Camphausen, Robin; Eggleton, Benjamin J.; Palomba, Stefano

2017-11-01

Breakdown flashes are undesired photo-emissions from the active area of single-photon avalanche photo-diodes. They arise from radiative recombinations of hot carriers generated during an avalanche and can induce crosstalk, compromise the measurement of optical quantum states, and hinder the security of quantum communications. Although the spectrum of this emission extends over hundreds of nanometers, active quenching may lead to a smaller uncertainty in the time of emission, thus enabling deterministic filtering. Our results pave the way to broadband interference mitigation in time-correlated single-photon applications.

Spectral Variations of T Tauri stars

NASA Astrophysics Data System (ADS)

Guenther, E.

1994-02-01

Although it can now be taken for granted that T Tauri stars accrete matter from circumstellar disks, the way in which the matter is ultimately accreted by the star is still under discussion. Boundary layer models, as well as models of magnetic accretion are considered. Since the very inner part of the disk, the star, and the boundary layer or the accretion shock radiate mainly in the optical, it is necessary to investigate this wavelength region. Optical spectra of classical T Tauri stars consist of emission lines superimposed on a late-type photospheric spectrum, but the photospheric lines in T Tauri stars are much weaker than the lines of main sequence stars of the same spectral type. This is generally attributed to the presence of an additional continuum which veils the photospheric spectrum of the star, which may be be the emission of the boundary layer, or the emission of the immediate vicinity of an accretion shock. The aim of this work is to give additional information on the nature of the region that emits the veiling continuum by investigating the correlations between the veiling and line fluxes in time serieses of T Tauri stars. For this work a time series of 27, 117, and 89 spectra of BM And, DI Cep and DG Tau, were taken in 9, 13, and 12 nights, using the Echellette-Spectrograph of the 2.2m telescope on Calar Alto, Spain. These T Tauri stars were selected because of their different of levels of activity. The spectra cover the whole region between 3200Å and 11000Å with a resolution of about Δ λ λ = 3000. Using 32 template stars the spectral types of the stars were determined, which is found to remain unchanged during the whole time series. The wavelengths of all photospheric lines are in agreement with a single doppler shift (+/- 6 km/s), which is taken as the systemic velocity. It is thus assumed that the low excitation lines are indeed the photospheric lines of the star and the veiling is an additional continuum source. The spectrum of the veiling continuum is determined by subtracting a flux calibrated, scaled template spectrum from the flux calibrated, deredened T Taui star spectrum. The spectra of the veiling continuum exhibit a strong, variable Balmer Jump, but no Pashen Jump is seen. Hα is the only emission line in the spectrum of BM And, all other Balmer lines and the lines of He I appear in absorption, and are redshifted by at least 100 km/s. While the correlation between Hα and the veiling continuum is high, the correlation between all redshifted absorption lines and the veiling continuum is very low. From a comparison of observed and computed profiles of He I it is concluded that this line might form close to an accretion shock, and so should the higher Balmer. Since no redshifted absorption component is seen in Hα, the emission component must be optically thick, and should then be formed at a larger distance from the star than the redshifted absorption components, and hence the veiling continuum. The observations of BM And clearly show that the magnetic model is valid in this case, but the veiling continuum is not the emission of the accretion shock itself. DG Tau and DI Cep show the same kind of behavior. All emission lines have correlation factors between about 0.3 and 0.8. The highest correlations are found in the Balmer lines and low excitation Fe I and Fe II lines. There are no delay effects between the lines, all lines reach their maxima and minima at the same time. From the large Balmer decrement, and calculation of the Balmer lines and the veiling continuum in a simple slab model, it is concluded that the emitting region that is responsible for the emission lines and the veiling continuum has a temperature of 10000 K, and a density of 3**1018m-3 or less. In the slab geometry this corresponds to an emitting region which is at least 10000 km (≅ 0.01 R*) thick. It can thus be concluded that the region emitting the veiling continuum is relatively large and thin.

Overweight and Obesity: Prevalence and Correlates in a Large Clinical Sample of Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Zuckerman, Katharine E.; Hill, Alison P.; Guion, Kimberly; Voltolina, Lisa; Fombonne, Eric

2014-01-01

Autism Spectrum Disorders (ASDs) and childhood obesity (OBY) are rising public health concerns. This study aimed to evaluate the prevalence of overweight (OWT) and OBY in a sample of 376 Oregon children with ASD, and to assess correlates of OWT and OBY in this sample. We used descriptive statistics, bivariate, and focused multivariate analyses to…

Couplings between hierarchical conformational dynamics from multi-time correlation functions and two-dimensional lifetime spectra: Application to adenylate kinase

NASA Astrophysics Data System (ADS)

Ono, Junichi; Takada, Shoji; Saito, Shinji

2015-06-01

An analytical method based on a three-time correlation function and the corresponding two-dimensional (2D) lifetime spectrum is developed to elucidate the time-dependent couplings between the multi-timescale (i.e., hierarchical) conformational dynamics in heterogeneous systems such as proteins. In analogy with 2D NMR, IR, electronic, and fluorescence spectroscopies, the waiting-time dependence of the off-diagonal peaks in the 2D lifetime spectra can provide a quantitative description of the dynamical correlations between the conformational motions with different lifetimes. The present method is applied to intrinsic conformational changes of substrate-free adenylate kinase (AKE) using long-time coarse-grained molecular dynamics simulations. It is found that the hierarchical conformational dynamics arise from the intra-domain structural transitions among conformational substates of AKE by analyzing the one-time correlation functions and one-dimensional lifetime spectra for the donor-acceptor distances corresponding to single-molecule Förster resonance energy transfer experiments with the use of the principal component analysis. In addition, the complicated waiting-time dependence of the off-diagonal peaks in the 2D lifetime spectra for the donor-acceptor distances is attributed to the fact that the time evolution of the couplings between the conformational dynamics depends upon both the spatial and temporal characters of the system. The present method is expected to shed light on the biological relationship among the structure, dynamics, and function.

Couplings between hierarchical conformational dynamics from multi-time correlation functions and two-dimensional lifetime spectra: Application to adenylate kinase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ono, Junichi; Takada, Shoji; Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502

2015-06-07

An analytical method based on a three-time correlation function and the corresponding two-dimensional (2D) lifetime spectrum is developed to elucidate the time-dependent couplings between the multi-timescale (i.e., hierarchical) conformational dynamics in heterogeneous systems such as proteins. In analogy with 2D NMR, IR, electronic, and fluorescence spectroscopies, the waiting-time dependence of the off-diagonal peaks in the 2D lifetime spectra can provide a quantitative description of the dynamical correlations between the conformational motions with different lifetimes. The present method is applied to intrinsic conformational changes of substrate-free adenylate kinase (AKE) using long-time coarse-grained molecular dynamics simulations. It is found that the hierarchicalmore » conformational dynamics arise from the intra-domain structural transitions among conformational substates of AKE by analyzing the one-time correlation functions and one-dimensional lifetime spectra for the donor-acceptor distances corresponding to single-molecule Förster resonance energy transfer experiments with the use of the principal component analysis. In addition, the complicated waiting-time dependence of the off-diagonal peaks in the 2D lifetime spectra for the donor-acceptor distances is attributed to the fact that the time evolution of the couplings between the conformational dynamics depends upon both the spatial and temporal characters of the system. The present method is expected to shed light on the biological relationship among the structure, dynamics, and function.« less

Minimum spanning tree filtering of correlations for varying time scales and size of fluctuations

NASA Astrophysics Data System (ADS)

Kwapień, Jarosław; Oświecimka, Paweł; Forczek, Marcin; DroŻdŻ, Stanisław

2017-05-01

Based on a recently proposed q -dependent detrended cross-correlation coefficient, ρq [J. Kwapień, P. Oświęcimka, and S. Drożdż, Phys. Rev. E 92, 052815 (2015), 10.1103/PhysRevE.92.052815], we generalize the concept of the minimum spanning tree (MST) by introducing a family of q -dependent minimum spanning trees (q MST s ) that are selective to cross-correlations between different fluctuation amplitudes and different time scales of multivariate data. They inherit this ability directly from the coefficients ρq, which are processed here to construct a distance matrix being the input to the MST-constructing Kruskal's algorithm. The conventional MST with detrending corresponds in this context to q =2 . In order to illustrate their performance, we apply the q MSTs to sample empirical data from the American stock market and discuss the results. We show that the q MST graphs can complement ρq in disentangling "hidden" correlations that cannot be observed in the MST graphs based on ρDCCA, and therefore, they can be useful in many areas where the multivariate cross-correlations are of interest. As an example, we apply this method to empirical data from the stock market and show that by constructing the q MSTs for a spectrum of q values we obtain more information about the correlation structure of the data than by using q =2 only. More specifically, we show that two sets of signals that differ from each other statistically can give comparable trees for q =2 , while only by using the trees for q ≠2 do we become able to distinguish between these sets. We also show that a family of q MSTs for a range of q expresses the diversity of correlations in a manner resembling the multifractal analysis, where one computes a spectrum of the generalized fractal dimensions, the generalized Hurst exponents, or the multifractal singularity spectra: the more diverse the correlations are, the more variable the tree topology is for different q 's. As regards the correlation structure of the stock market, our analysis exhibits that the stocks belonging to the same or similar industrial sectors are correlated via the fluctuations of moderate amplitudes, while the largest fluctuations often happen to synchronize in those stocks that do not necessarily belong to the same industry.

Demographic and clinical correlates of autism symptom domains and autism spectrum diagnosis.

PubMed

Frazier, Thomas W; Youngstrom, Eric A; Embacher, Rebecca; Hardan, Antonio Y; Constantino, John N; Law, Paul; Findling, Robert L; Eng, Charis

2014-07-01

Demographic and clinical factors may influence assessment of autism symptoms. This study evaluated these correlates and also examined whether social communication and interaction and restricted/repetitive behavior provided unique prediction of autism spectrum disorder diagnosis. We analyzed data from 7352 siblings included in the Interactive Autism Network registry. Social communication and interaction and restricted/repetitive behavior symptoms were obtained using caregiver-reports on the Social Responsiveness Scale. Demographic and clinical correlates were covariates in regression models predicting social communication and interaction and restricted/repetitive behavior symptoms. Logistic regression and receiver operating characteristic curve analyses evaluated the incremental validity of social communication and interaction and restricted/repetitive behavior domains over and above global autism symptoms. Autism spectrum disorder diagnosis was the strongest correlate of caregiver-reported social communication and interaction and restricted/repetitive behavior symptoms. The presence of comorbid diagnoses also increased symptom levels. Social communication and interaction and restricted/repetitive behavior symptoms provided significant, but modest, incremental validity in predicting diagnosis beyond global autism symptoms. These findings suggest that autism spectrum disorder diagnosis is by far the largest determinant of quantitatively measured autism symptoms. Externalizing (attention deficit hyperactivity disorder) and internalizing (anxiety) behavior, low cognitive ability, and demographic factors may confound caregiver-report of autism symptoms, potentially necessitating a continuous norming approach to the revision of symptom measures. Social communication and interaction and restricted/repetitive behavior symptoms may provide incremental validity in the diagnosis of autism spectrum disorder. © The Author(s) 2013.

Demographic and clinical correlates of autism symptom domains and autism spectrum diagnosis

PubMed Central

Frazier, Thomas W; Youngstrom, Eric A; Embacher, Rebecca; Hardan, Antonio Y; Constantino, John N; Law, Paul; Findling, Robert L; Eng, Charis

2014-01-01

Demographic and clinical factors may influence assessment of autism symptoms. This study evaluated these correlates and also examined whether social communication and interaction and restricted/repetitive behavior provided unique prediction of autism spectrum disorder diagnosis. We analyzed data from 7352 siblings included in the Interactive Autism Network registry. Social communication and interaction and restricted/repetitive behavior symptoms were obtained using caregiver-reports on the Social Responsiveness Scale. Demographic and clinical correlates were covariates in regression models predicting social communication and interaction and restricted/repetitive behavior symptoms. Logistic regression and receiver operating characteristic curve analyses evaluated the incremental validity of social communication and interaction and restricted/repetitive behavior domains over and above global autism symptoms. Autism spectrum disorder diagnosis was the strongest correlate of caregiver-reported social communication and interaction and restricted/repetitive behavior symptoms. The presence of comorbid diagnoses also increased symptom levels. Social communication and interaction and restricted/repetitive behavior symptoms provided significant, but modest, incremental validity in predicting diagnosis beyond global autism symptoms. These findings suggest that autism spectrum disorder diagnosis is by far the largest determinant of quantitatively measured autism symptoms. Externalizing (attention deficit hyperactivity disorder) and internalizing (anxiety) behavior, low cognitive ability, and demographic factors may confound caregiver-report of autism symptoms, potentially necessitating a continuous norming approach to the revision of symptom measures. Social communication and interaction and restricted/repetitive behavior symptoms may provide incremental validity in the diagnosis of autism spectrum disorder. PMID:24104512

On using large scale correlation of the Ly-α forest and redshifted 21-cm signal to probe HI distribution during the post reionization era

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Tapomoy Guha; Datta, Kanan K., E-mail: tapomoy@pilani.bits-pilani.ac.in, E-mail: kanan.physics@presiuniv.ac.in

We investigate the possibility of detecting the 3D cross correlation power spectrum of the Ly-α forest and HI 21 cm signal from the post reionization epoch. (The cross-correlation signal is directly dependent on the dark matter power spectrum and is sensitive to the 21-cm brightness temperature and Ly-α forest biases. These bias parameters dictate the strength of anisotropy in redshift space.) We find that the cross-correlation power spectrum can be detected using 400 hrs observation with SKA-mid (phase 1) and a futuristic BOSS like experiment with a quasar (QSO) density of 30 deg{sup −2} at a peak SNR of 15 for amore » single field experiment at redshift z = 2.5. on large scales using the linear bias model. We also study the possibility of constraining various bias parameters using the cross power spectrum. We find that with the same experiment 1 σ (conditional errors) on the 21-cm linear redshift space distortion parameter β{sub T} and β{sub F} corresponding to the Ly-α  forest are ∼ 2.7 % and ∼ 1.4 % respectively for 01 independent pointings of the SKA-mid (phase 1). This prediction indicates a significant improvement over existing measurements. We claim that the detection of the 3D cross correlation power spectrum will not only ascertain the cosmological origin of the signal in presence of astrophysical foregrounds but will also provide stringent constraints on large scale HI biases. This provides an independent probe towards understanding cosmological structure formation.« less

Dual-radiotracer translational SPECT neuroimaging. Comparison of three methods for the simultaneous brain imaging of D2/3 and 5-HT2A receptors.

PubMed

Tsartsalis, Stergios; Tournier, Benjamin B; Habiby, Selim; Ben Hamadi, Meriem; Barca, Cristina; Ginovart, Nathalie; Millet, Philippe

2018-04-30

SPECT imaging with two radiotracers at the same time is feasible if two different radioisotopes are employed, given their distinct energy emission spectra. In the case of 123 I and 125 I, dual SPECT imaging is not straightforward: 123 I emits photons at a principal energy emission spectrum of 143.1-179.9 keV. However, it also emits at a secondary energy spectrum (15-45 keV) that overlaps with the one of 125 I and the resulting cross-talk of emissions impedes the accurate quantification of 125 I. In this paper, we describe three different methods for the correction of this cross-talk and the simultaneous in vivo [ 123 I]IBZM and [ 125 I]R91150 imaging of D 2/3 and 5-HT 2A receptors in the rat brain. Three methods were evaluated for the correction of the effect of cross-talk in a series of simultaneous, [ 123 I]IBZM and [ 125 I]R91150 in vivo and phantom SPECT scans. Method 1 employs a dual-energy window (DEW) approach, in which the cross-talk on 125 I is considered a stable fraction of the energy emitted from 123 I at the principal emission spectrum. The coefficient describing the relationship between the emission of 123 I at the principal and the secondary spectrum was estimated from a series of single-radiotracer [ 123 I]IBZM SPECT studies. In Method 2, spectral factor analysis (FA) is applied to separate the radioactivity from 123 I and 125 I on the basis of their distinct emission patterns across the energy spectrum. Method 3 uses a modified simplified reference tissue model (SRTM C ) to describe the kinetics of [ 125 I]R91150. It includes the coefficient describing the cross-talk on 125 I from 123 I in the model parameters. The results of the correction of cross-talk on [ 125 I]R91150 binding potential (BP ND ) with each of the three methods, using cerebellum as the reference region, were validated against the results of a series of single-radiotracer [ 123 I]R91150 SPECT studies. In addition, the DEW approach (Method 1), considered to be the most straightforward to apply of the three, was further applied in a dual-radiotracer SPECT study of the relationship between D 2/3 and 5-HT 2A receptor binding in the striatum, both at the voxel and at the regional level. Average regional BP ND values of [ 125 I]R91150, estimated on the cross-talk corrected dual-radiotracer SPECT studies provided satisfactory correlations with the BP ND values for [ 123 I]R91150 from single-radiotracer studies: r = 0.92, p < 0.001 for Method 1, r = 0.92, p < 0.001 for Method 2, r = 0.92, p < 0.001, for Method 3. The coefficient describing the ratio of the 123 I-emitted radioactivity at the 125 I-emission spectrum to the radioactivity that it emits at its principal emission spectrum was 0.34 in vivo. Dual-radiotracer in vivo SPECT studies corrected with Method 1 demonstrated a positive correlation between D 2/3 and 5-HT 2A receptor binding in the rat nucleus accumbens at the voxel level. At the VOI-level, a positive correlation was confirmed in the same region (r = 0.78, p < 0.01). Dual-radiotracer SPECT imaging using 123 I and 125 I-labeled radiotracers is feasible if the cross-talk of 123 I on the 125 I emission spectrum is properly corrected. The most straightforward approach is Method 1, in which a fraction (34%) of the radioactivity emitted from 123 I at its principal energy spectrum is subtracted from the measured radioactivity at the spectrum of 125 I. With this method, a positive correlation between the binding of [ 123 I]IBZM and [ 125 I]R91150 was demonstrated in the rat nucleus accumbens. This result highlights the interest of dual-radiotracer SPECT imaging to study multiple neurotransmitter systems at the same time and under the same biological conditions. Copyright © 2018 Elsevier Inc. All rights reserved.

Parametric spectro-temporal analyzer (PASTA) for real-time optical spectrum observation

NASA Astrophysics Data System (ADS)

Zhang, Chi; Xu, Jianbing; Chui, P. C.; Wong, Kenneth K. Y.

2013-06-01

Real-time optical spectrum analysis is an essential tool in observing ultrafast phenomena, such as the dynamic monitoring of spectrum evolution. However, conventional method such as optical spectrum analyzers disperse the spectrum in space and allocate it in time sequence by mechanical rotation of a grating, so are incapable of operating at high speed. A more recent method all-optically stretches the spectrum in time domain, but is limited by the allowable input condition. In view of these constraints, here we present a real-time spectrum analyzer called parametric spectro-temporal analyzer (PASTA), which is based on the time-lens focusing mechanism. It achieves a frame rate as high as 100 MHz and accommodates various input conditions. As a proof of concept and also for the first time, we verify its applications in observing the dynamic spectrum of a Fourier domain mode-locked laser, and the spectrum evolution of a laser cavity during its stabilizing process.

Randoms Counter Analysis

NASA Astrophysics Data System (ADS)

Hensley, Winston; Giovanetti, Kevin

2008-10-01

A 1 ppm precision measurement of the muon lifetime is being conducted by the MULAN collaboration. The reason for this new measurement lies in recent advances in theory that have reduced the uncertainty in calculating the Fermi Coupling Constant from the measured lifetime to a few tenths ppm. The largest uncertainty is now experimental. To achieve a 1ppm level of precision it is necessary to control all sources of systematic error and to understand their influences on the lifetime measurement. James Madison University is contributing by examine the response of the timing system to uncorrelated events, randoms. A radioactive source was placed in front of paired detectors similar to those in the main experiment. These detectors were integrated in an identical fashion into the data acquisition and measurement system and data from these detectors was recorded during the entire experiment. The pair were placed in a shielded enclosure away from the main experiment to minimize interference. The data from these detectors should have a flat time spectrum as the decay of a radioactive source is a random event and has no time correlation. Thus the spectrum can be used as an important diagnostic in studying the method of determining event times and timing system performance.

TEMPORAL CORRELATIONS BETWEEN OPTICAL AND GAMMA-RAY ACTIVITY IN BLAZARS

DOE PAGES

Cohen, Daniel P.; Romani, Roger W.; Filippenko, Alexei V.; ...

2014-12-08

For this research, we have been using the 0.76 m Katzman Automatic Imaging Telescope (KAIT) at Lick Observatory to optically monitor a sample of 157 blazars that are bright in gamma-rays being detected with high significance (≥10σ) in one year by the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. We attempt to observe each source on a three-day cadence with KAIT, subject to weather and seasonal visibility. The gamma-ray coverage is essentially continuous. KAIT observations extend over much of the five-year Fermi mission for several objects, and most have >100 optical measurements spanning the last three years.more » These blazars (flat-spectrum radio quasars and BL Lac objects) exhibit a wide range of flaring behavior. Using the discrete correlation function (DCF), here we search for temporal relationships between optical and gamma-ray light curves in the 40 brightest sources in hopes of placing constraints on blazar acceleration and emission zones. We find strong optical-gamma-ray correlation in many of these sources at time delays of ~1 to ~10 days, ranging between –40 and +30 days. A stacked average DCF of the 40 sources verifies this correlation trend, with a peak above 99% significance indicating a characteristic time delay consistent with 0 days. These findings strongly support the widely accepted leptonic models of blazar emission. However, we also find examples of apparently uncorrelated flares (optical flares with no gamma-ray counterpart and gamma-ray flares with no optical counterpart) that challenge simple, one-zone models of blazar emission. Moreover, we find that flat-spectrum radio quasars tend to have gamma-rays leading the optical, while intermediate- and high-synchrotron peak blazars with the most significant peaks have smaller lags/leads. In conclusion, it is clear that long-term monitoring at high cadence is necessary to reveal the underlying physical correlation.« less

Reliability of Sleep Measures from Four Personal Health Monitoring Devices Compared to Research-Based Actigraphy and Polysomnography.

PubMed

Mantua, Janna; Gravel, Nickolas; Spencer, Rebecca M C

2016-05-05

Polysomnography (PSG) is the "gold standard" for monitoring sleep. Alternatives to PSG are of interest for clinical, research, and personal use. Wrist-worn actigraph devices have been utilized in research settings for measures of sleep for over two decades. Whether sleep measures from commercially available devices are similarly valid is unknown. We sought to determine the validity of five wearable devices: Basis Health Tracker, Misfit Shine, Fitbit Flex, Withings Pulse O2, and a research-based actigraph, Actiwatch Spectrum. We used Wilcoxon Signed Rank tests to assess differences between devices relative to PSG and correlational analysis to assess the strength of the relationship. Data loss was greatest for Fitbit and Misfit. For all devices, we found no difference and strong correlation of total sleep time with PSG. Sleep efficiency differed from PSG for Withings, Misfit, Fitbit, and Basis, while Actiwatch mean values did not differ from that of PSG. Only mean values of sleep efficiency (time asleep/time in bed) from Actiwatch correlated with PSG, yet this correlation was weak. Light sleep time differed from PSG (nREM1 + nREM2) for all devices. Measures of Deep sleep time did not differ from PSG (SWS + REM) for Basis. These results reveal the current strengths and limitations in sleep estimates produced by personal health monitoring devices and point to a need for future development.

Investigation of the Association Between Motor Stereotypy Behavior With Fundamental Movement Skills, Adaptive Functioning, and Autistic Spectrum Disorder Symptomology in Children With Intellectual Disabilities.

PubMed

Powell, Joanne L; Pringle, Lydia; Greig, Matt

2017-02-01

Motor stereotypy behaviors are patterned, coordinated, repetitive behaviors that are particularly evident in those with an autistic spectrum disorder and intellectual disabilities. The extent to which motor stereotypy behavior severity is associated with motor skills and maladaptive behavior, measures of adaptive functioning, along with fundamental movement skills and degree of autistic spectrum disorder symptomology is assessed in this preliminary report. Twelve participants, aged 7 to 16 years, with a reported motor stereotypy behavior and either mild or severe intellectual disability comprising developmental or global delay took part in the study. Spearman rho correlational analysis showed that severity of motor stereotypy behavior was significantly positively correlated with autistic spectrum disorder symptomology ( P = .008) and maladaptive behavior ( P = .008) but not fundamental movement skills ( P > .05). An increase in fundamental movement skills score was associated with a decrease in autistic spectrum disorder symptomology ( P = .01) and an increase in motor skills ( P = .002). This study provides evidence showing a significant relationship between motor stereotypy behavior severity with degree of autistic spectrum disorder symptomology and maladaptive behavior.

The Neural Substrates of Cognitive Control Deficits in Autism Spectrum Disorders

PubMed Central

Solomon, Marjorie; Ozonoff, Sally; Ursu, Stefan; Ravizza, Susan; Cummings, Neil; Ly, Stanford; Carter, Cameron

2009-01-01

Executive functions deficits are among the most frequently reported symptoms of autism spectrum disorders (ASDs), however, there have been few functional magnetic resonance imaging (fMRI) studies that investigate the neural substrates of executive functions deficits in ASDs, and only one in adolescents. The current study examined cognitive control –the ability to maintain task context online to support adaptive functioning in the face of response competition—in 22 adolescents aged 12–18 with autism spectrum disorders and 23 age, gender, and IQ matched typically developing subjects. During the cue phase of the task, where subjects must maintain information online to overcome a prepotent response tendency, typically developing subjects recruited significantly more anterior frontal (BA 10), parietal (BA 7, 40), and occipital regions (BA 18) for high control trials (25% of trials) versus low control trials (75% of trials). Both groups showed similar activation for low control cues, however the ASD group exhibited significantly less activation for high control cues. Functional connectivity analysis using time series correlation, factor analysis, and beta series correlation methods provided convergent evidence that the ASD group exhibited lower levels of functional connectivity and less network integration between frontal, parietal, and occipital regions. In the typically developing group, fronto-parietal connectivity was related to lower error rates on high control trials. In the autism group, reduced fronto-parietal connectivity was related to attention deficit hyperactivity disorder symptoms. PMID:19410583

Chandra Phase-Resolved Spectroscopy of the High-Magnetic-Field Pulsar B1509-58

NASA Astrophysics Data System (ADS)

Hu, Chin-Ping; Ng, Chi-Yung

2016-04-01

We report on timing and spectral analysis of the young, high-magnetic-field pulsar B1509-58 using Chandra continuous-clocking mode observation. The on-pulsed X-ray spectrum can be described by a power law with a photon index of 1.16(2), which is flatter than those determined with RXTE/PCA and NuSTAR. This result supports the log-parabolic model for the broadband X-ray spectrum. With the unprecedented angular resolution of Chandra, we clearly identified off-pulsed X-ray emission from the pulsar. The spectrum is best fitted by a power law plus blackbody model. The latter component has a temperature of ~0.14 keV, which is similar to those of other young and high-magnetic-field pulsars, and lies between those of magnetars and typical rotational-powered pulsars. For the non-thermal emission of PSR B1509-58, we found that the power law component of the off-pulsed emission is significantly steeper than that of the on-pulsed one. We further divided the data into 24 phase bins and found that the photon index varies between 1.0 and 2.0 and anti-correlating with the flux. A similar correlation was also found in the Crab Pulsar, and this requires further theoretical interpretations. This work is supported by a GRF grant of Hong Kong Government under 17300215.

An inventory of bispectrum estimators for redshift space distortions

NASA Astrophysics Data System (ADS)

Regan, Donough

2017-12-01

In order to best improve constraints on cosmological parameters and on models of modified gravity using current and future galaxy surveys it is necessary maximally exploit the available data. As redshift-space distortions mean statistical translation invariance is broken for galaxy observations, this will require measurement of the monopole, quadrupole and hexadecapole of not just the galaxy power spectrum, but also the galaxy bispectrum. A recent (2015) paper by Scoccimarro demonstrated how the standard bispectrum estimator may be expressed in terms of Fast Fourier Transforms (FFTs) to afford an extremely efficient algorithm, allowing the bispectrum multipoles on all scales and triangle shapes to be measured in comparable time to those of the power spectrum. In this paper we present a suite of alternative proxies to measure the three-point correlation multipoles. In particular, we describe a modal (or plane wave) decomposition to capture the information in each multipole in a series of basis coefficients, and also describe three compressed estimators formed using the skew-spectrum, the line correlation function and the integrated bispectrum, respectively. As well as each of the estimators offering a different measurement channel, and thereby a robustness check, it is expected that some (especially the modal estimator) will offer a vast data compression, and so a much reduced covariance matrix. This compression may be vital to reduce the computational load involved in extracting the available three-point information.

Detection of diluted contaminants on chicken carcasses using a two-dimensional scatter plot based on a two-dimensional hyperspectral correlation spectrum.

PubMed

Wu, Wei; Chen, Gui-Yun; Wu, Ming-Qing; Yu, Zhen-Wei; Chen, Kun-Jie

2017-03-20

A two-dimensional (2D) scatter plot method based on the 2D hyperspectral correlation spectrum is proposed to detect diluted blood, bile, and feces from the cecum and duodenum on chicken carcasses. First, from the collected hyperspectral data, a set of uncontaminated regions of interest (ROIs) and four sets of contaminated ROIs were selected, whose average spectra were treated as the original spectrum and influenced spectra, respectively. Then, the difference spectra were obtained and used to conduct correlation analysis, from which the 2D hyperspectral correlation spectrum was constructed using the analogy method of 2D IR correlation spectroscopy. Two maximum auto-peaks and a pair of cross peaks appeared at 656 and 474 nm. Therefore, 656 and 474 nm were selected as the characteristic bands because they were most sensitive to the spectral change induced by the contaminants. The 2D scatter plots of the contaminants, clean skin, and background in the 474- and 656-nm space were used to distinguish the contaminants from the clean skin and background. The threshold values of the 474- and 656-nm bands were determined by receiver operating characteristic (ROC) analysis. According to the ROC results, a pixel whose relative reflectance at 656 nm was greater than 0.5 and relative reflectance at 474 nm was lower than 0.3 was judged as a contaminated pixel. A region with more than 50 pixels identified was marked in the detection graph. This detection method achieved a recognition rate of up to 95.03% at the region level and 31.84% at the pixel level. The false-positive rate was only 0.82% at the pixel level. The results of this study confirm that the 2D scatter plot method based on the 2D hyperspectral correlation spectrum is an effective method for detecting diluted contaminants on chicken carcasses.

The combined impact of social support and perceived stress on quality of life in adults with autism spectrum disorder and without intellectual disability.

PubMed

Bishop-Fitzpatrick, Lauren; Mazefsky, Carla A; Eack, Shaun M

2017-06-01

Identifying modifiable correlates of good quality of life in adults with autism spectrum disorder is of paramount importance for intervention development as the population of adults with autism spectrum disorder increases. This study sought to examine social support and perceived stress as potential modifiable correlates of quality of life in adults with autism spectrum disorder. We hypothesized that adults with autism spectrum disorder without co-occurring intellectual disabilities ( N = 40; aged 18-44 years) would report lower levels of social support and quality of life than typical community volunteers who were matched for age, sex, and race ( N = 25). We additionally hypothesized that social support would buffer the effect of perceived stress on quality of life in adults with autism spectrum disorder. Results indicated that adults with autism spectrum disorder reported significantly lower levels of social support and quality of life than matched typical community volunteers. In addition, findings showed significant direct effects of social support and perceived stress on quality of life in adults with autism spectrum disorder. Social support did not buffer the effect of perceived stress on quality of life. Interventions that teach adults with autism spectrum disorder skills to help them better manage stress and cultivate supportive social relationships have the potential to improve quality of life.

Direct and simultaneous detection of organic and inorganic ingredients in herbal powder preparations by Fourier transform infrared microspectroscopic imaging

NASA Astrophysics Data System (ADS)

Chen, Jian-bo; Sun, Su-qin; Tang, Xu-dong; Zhang, Jing-zhao; Zhou, Qun

2016-08-01

Herbal powder preparation is a kind of widely-used herbal product in the form of powder mixture of herbal ingredients. Identification of herbal ingredients is the first and foremost step in assuring the quality, safety and efficacy of herbal powder preparations. In this research, Fourier transform infrared (FT-IR) microspectroscopic identification method is proposed for the direct and simultaneous recognition of multiple organic and inorganic ingredients in herbal powder preparations. First, the reference spectrum of characteristic particles of each herbal ingredient is assigned according to FT-IR results and other available information. Next, a statistical correlation threshold is determined as the lower limit of correlation coefficients between the reference spectrum and a larger number of calibration characteristic particles. After validation, the reference spectrum and correlation threshold can be used to identify herbal ingredient in mixture preparations. A herbal ingredient is supposed to be present if correlation coefficients between the reference spectrum and some sample particles are above the threshold. Using this method, all kinds of herbal materials in powder preparation Kouqiang Kuiyang San are identified successfully. This research shows the potential of FT-IR microspectroscopic identification method for the accurate and quick identification of ingredients in herbal powder preparations.

High-Resolution Measurement of the Turbulent Frequency-Wavenumber Power Spectrum in a Laboratory Magnetosphere

NASA Astrophysics Data System (ADS)

Qian, T. M.; Mauel, M. E.

2017-10-01

In a laboratory magnetosphere, plasma is confined by a strong dipole magnet, where interchange and entropy mode turbulence can be studied and controlled in near steady-state conditions. Whole-plasma imaging shows turbulence dominated by long wavelength modes having chaotic amplitudes and phases. Here, we report for the first time, high-resolution measurement of the frequency-wavenumber power spectrum by applying the method of Capon to simultaneous multi-point measurement of electrostatic entropy modes using an array of floating potential probes. Unlike previously reported measurements in which ensemble correlation between two probes detected only the dominant wavenumber, Capon's ``maximum likelihood method'' uses all available probes to produce a frequency-wavenumber spectrum, showing the existence of modes propagating in both electron and ion magnetic drift directions. We also discuss the wider application of this technique to laboratory and magnetospheric plasmas with simultaneous multi-point measurements. Supported by NSF-DOE Partnership in Plasma Science Grant DE-FG02-00ER54585.

Two-dimensional NMR spectroscopy of 13C methanol at less than 5 μT

NASA Astrophysics Data System (ADS)

Shim, Jeong Hyun; Lee, Seong-Joo; Hwang, Seong-min; Yu, Kwon-Kyu; Kim, Kiwoong

2014-09-01

Two-dimensional (2D) spectroscopy is one of the most significant applications of nuclear magnetic resonance (NMR). Here, we demonstrate that the 2D NMR can be performed even at a low magnetic field of less than 5 μT, which is ten times less than the Earth’s magnetic field. The pulses used in the experiment were composed of circularly polarized fields for coherent as well as wideband excitations. Since the excitation band covers the entire spectral range, the simplest two-pulse sequence delivered the full 2D spectrum. At 5 μT, methanol with 13C enriched up to 99% belongs to a strongly coupled regime, and thus its 2D spectrum exhibits complicated spectral correlations, which can be exploited as a fingerprint in chemical analysis. In addition, we show that, with compressive sensing, the acquisition of the 2D spectrum can be accelerated to take only 45% of the overall duration.

Statistics of pressure and pressure gradient in homogeneous isotropic turbulence

NASA Technical Reports Server (NTRS)

Gotoh, T.; Rogallo, R. S.

1994-01-01

The statistics of pressure and pressure gradient in stationary isotropic turbulence are measured within direct numerical simulations at low to moderate Reynolds numbers. It is found that the one-point pdf of the pressure is highly skewed and that the pdf of the pressure gradient is of stretched exponential form. The power spectrum of the pressure P(k) is found to be larger than the corresponding spectrum P(sub G)(k) computed from a Gaussian velocity field having the same energy spectrum as that of the DNS field. The ratio P(k)/P(sub G)(k), a measure of the pressure-field intermittence, grows with wavenumber and Reynolds number as -R(sub lambda)(exp 1/2)log(k/k(sub d)) for k less than k(sub d)/2 where k(sub d) is the Kolmogorov wavenumber. The Lagrangian correlations of pressure gradient and velocity are compared and the Lagrangian time scale of the pressure gradient is observed to be much shorter than that of the velocity.

Real-Time Analysis of the Heart Rate Variability During Incremental Exercise for the Detection of the Ventilatory Threshold.

PubMed

Shiraishi, Yasuyuki; Katsumata, Yoshinori; Sadahiro, Taketaro; Azuma, Koichiro; Akita, Keitaro; Isobe, Sarasa; Yashima, Fumiaki; Miyamoto, Kazutaka; Nishiyama, Takahiko; Tamura, Yuichi; Kimura, Takehiro; Nishiyama, Nobuhiro; Aizawa, Yoshiyasu; Fukuda, Keiichi; Takatsuki, Seiji

2018-01-07

It has never been possible to immediately evaluate heart rate variability (HRV) during exercise. We aimed to visualize the real-time changes in the power spectrum of HRV during exercise and to investigate its relationship to the ventilatory threshold (VT). Thirty healthy subjects (29.1±5.7 years of age) and 35 consecutive patients (59.0±13.2 years of age) with myocardial infarctions underwent cardiopulmonary exercise tests with an RAMP protocol ergometer. The HRV was continuously assessed with power spectral analyses using the maximum entropy method and projected on a screen without delay. During exercise, a significant decrease in the high frequency (HF) was followed by a drastic shift in the power spectrum of the HRV with a periodic augmentation in the low frequency/HF (L/H) and steady low HF. When the HRV threshold (HRVT) was defined as conversion from a predominant high frequency (HF) to a predominant low frequency/HF (L/H), the VO 2 at the HRVT (HRVT-VO 2 ) was substantially correlated with the VO 2 at the lactate threshold and VT) in the healthy subjects ( r =0.853 and 0.921, respectively). The mean difference between each threshold (0.65 mL/kg per minute for lactate threshold and HRVT, 0.53 mL/kg per minute for VT and HRVT) was nonsignificant ( P >0.05). Furthermore, the HRVT-VO 2 was also correlated with the VT-VO 2 in these myocardial infarction patients ( r =0.867), and the mean difference was -0.72 mL/kg per minute and was nonsignificant ( P >0.05). A HRV analysis with our method enabled real-time visualization of the changes in the power spectrum during exercise. This can provide additional information for detecting the VT. © 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

The Atacama Cosmology Telescope: Cross-Correlation of Cosmic Microwave Background Lensing and Quasars

NASA Technical Reports Server (NTRS)

Sherwin, Blake D; Das, Sudeep; Haijian, Amir; Addison, Graeme; Bond, Richard; Crichton, Devin; Devlin, Mark J.; Dunkley, Joanna; Gralla, Megan B.; Halpern, Mark;

Discovery of X-Ray Emission from the Galactic Supernova Remnant G32.8-0.1 with Suzaku

NASA Astrophysics Data System (ADS)

Bamba, Aya; Terada, Yukikatsu; Hewitt, John; Petre, Robert; Angelini, Lorella; Safi-Harb, Samar; Zhou, Ping; Bocchino, Fabrizio; Sawada, Makoto

2016-02-01

We present the first dedicated X-ray study of the supernova remnant (SNR) G32.8-0.1 (Kes 78) with Suzaku. X-ray emission from the whole SNR shell has been detected for the first time. The X-ray morphology is well correlated with the emission from the radio shell, while anti-correlated with the molecular cloud found in the SNR field. The X-ray spectrum shows not only conventional low-temperature (kT ˜ 0.6 keV) thermal emission in a non-equilibrium ionization state, but also a very high-temperature (kT ˜ 3.4 keV) component with a very low ionization timescale (˜2.7 × 109 cm-3 s), or a hard nonthermal component with a photon index Γ ˜ 2.3. The average density of the low-temperature plasma is rather low, of the order of 10-3-10-2 cm-3, implying that this SNR is expanding into a low-density cavity. We discuss the X-ray emission of the SNR, also detected in TeV with H.E.S.S., together with multi-wavelength studies of the remnant and other gamma-ray emitting SNRs, such as W28 and RCW 86. Analysis of a time-variable source, 2XMM J185114.3-000004, found in the northern part of the SNR, is also reported for the first time. Rapid time variability and a heavily absorbed hard-X-ray spectrum suggest that this source could be a new supergiant fast X-ray transient.

No evidence of reaction time slowing in autism spectrum disorder.

PubMed

Ferraro, F Richard

2016-01-01

A total of 32 studies comprising 238 simple reaction time and choice reaction time conditions were examined in individuals with autism spectrum disorder (n = 964) and controls (n = 1032). A Brinley plot/multiple regression analysis was performed on mean reaction times, regressing autism spectrum disorder performance onto the control performance as a way to examine any generalized simple reaction time/choice reaction time slowing exhibited by the autism spectrum disorder group. The resulting regression equation was Y (autism spectrum disorder) = 0.99 × (control) + 87.93, which accounted for 92.3% of the variance. These results suggest that there are little if any simple reaction time/choice reaction time slowing in this sample of individual with autism spectrum disorder, in comparison with controls. While many cognitive and information processing domains are compromised in autism spectrum disorder, it appears that simple reaction time/choice reaction time remain relatively unaffected in autism spectrum disorder. © The Author(s) 2014.

Simultaneous Spectral and Timing Observations of Accreting Neuron Stars

NASA Technical Reports Server (NTRS)

Kaaret, P.; Oliversen, Ronald J. (Technical Monitor)

2002-01-01

The goal of this proposal is to perform simultaneous x-ray spectral and millisecond timing observations of accreting neutron stars to further our understanding of their accretion dynamics and in the hope of using these systems as probes of the physics of strong gravitational fields. NAG5-9104 is the successor grant to NAG5-8408. Observations using the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAX were performed of 4U1702-429, 4U1735-44, and Cyg X-2. Unfortunately, only a small fraction of the approved observing time was obtained for the first two targets and the data are of limited scientific value. Data analysis has been completed on the observations of Cyg X-2. We discovered a correlation between the frequency of the horizontal branch oscillations (HBO) and a soft, thermal component of the x-ray spectrum likely associated with emission from the accretion disk. This correlation may place constraints on models of the oscillations. A paper based on these results appeared in the Astrophysical Journal.

Design and analysis of coherent OCDM en/decoder based on photonic crystal

NASA Astrophysics Data System (ADS)

Zhang, Chongfu; Qiu, Kun

2008-08-01

The design and performance analysis of a new coherent optical en/decoder based on photonic crystal (PhC) for optical code -division -multiple (OCDM) are presented in this paper. In this scheme, the optical pulse phase and time delay can be flexibly controlled by photonic crystal phase shifter and time delayer by using the appropriate design of fabrication. According to the PhC transmission matrix theorem, combination calculation of the impurity and normal period layers is applied, and performances of the PhC-based optical en/decoder are also analyzed. The reflection, transmission, time delay characteristic and optical spectrum of pulse en/decoded are studied for the waves tuned in the photonic band-gap by numerical calculation. Theoretical analysis and numerical results indicate that the optical pulse is achieved to properly phase modulation and time delay, and an auto-correlation of about 8 dB ration and cross-correlation is gained, which demonstrates the applicability of true pulse phase modulation in a number of applications.

VizieR Online Data Catalog: RV of candidate hybrid variable stars (Lampens+, 2018)

NASA Astrophysics Data System (ADS)

Lampens, P.; Fremat, Y.; Vermeylen, L.; Sodor, A.; Skarka, M.; De Cat, P.; Bognar, Zs.; de Nutte, R.; Dumortier, L.; Escorza, A.; Oomen, G. M.; van de Steene, G.; Kamath, D.; Laverick, M.; Samadi, A.; Triana, S.; Lehmann, H.

2017-09-01

We present the individual radial velocity measurements of 50 candidate delta Scuti - gamma Doradus hybrid stars and one delta Scuti star from the Kepler mission collected with the Hermes and Ace spectrographs over a time span of months to years. The radial velocities were measured using spectrum synthesis and a two-dimensional cross-correlation technique in the case of double- and triple-lined systems. (5 data files).

The foreign exchange market: return distributions, multifractality, anomalous multifractality and the Epps effect

NASA Astrophysics Data System (ADS)

Drożdż, Stanisław; Kwapień, Jarosław; Oświȩcimka, Paweł; Rak, Rafał

2010-10-01

We present a systematic study of various statistical characteristics of high-frequency returns from the foreign exchange market. This study is based on six exchange rates forming two triangles: EUR-GBP-USD and GBP-CHF-JPY. It is shown that the exchange rate return fluctuations for all of the pairs considered are well described by the non-extensive statistics in terms of q-Gaussians. There exist some small quantitative variations in the non-extensivity q-parameter values for different exchange rates (which depend also on the time scales studied), and this can be related to the importance of a given exchange rate in the world's currency trade. Temporal correlations organize the series of returns such that they develop the multifractal characteristics for all of the exchange rates, with a varying degree of symmetry of the singularity spectrum f(α), however. The most symmetric spectrum is identified for the GBP/USD. We also form time series of triangular residual returns and find that the distributions of their fluctuations develop disproportionately heavier tails as compared to small fluctuations, which excludes description in terms of q-Gaussians. The multifractal characteristics of these residual returns reveal such anomalous properties as negative singularity exponents and even negative singularity spectra. Such anomalous multifractal measures have so far been considered in the literature in connection with diffusion-limited aggregation and with turbulence. Studying the cross-correlations among different exchange rates, we found that market inefficiency on short time scales leads to the occurrence of the Epps effect on much longer time scales, but comparable to the ones for the stock market. Although the currency market is much more liquid than the stock markets and has a much greater transaction frequency, the building up of correlations takes up to several hours—a duration that does not differ much from what is observed in the stock markets. This may suggest that non-synchronicity of transactions is not the unique source of the observed effect.

Phase-synchronization, energy cascade, and intermittency in solar-wind turbulence.

PubMed

Perri, S; Carbone, V; Vecchio, A; Bruno, R; Korth, H; Zurbuchen, T H; Sorriso-Valvo, L

2012-12-14

The energy cascade in solar wind magnetic turbulence is investigated using MESSENGER data in the inner heliosphere. The decomposition of magnetic field time series in intrinsic functions, each characterized by a typical time scale, reveals phase reorganization. This allows for the identification of structures of all sizes generated by the nonlinear turbulent cascade, covering both the inertial and the dispersive ranges of the turbulent magnetic power spectrum. We find that the correlation (or anticorrelation) of phases occurs between pairs of neighboring time scales, whenever localized peaks of magnetic energy are present at both scales, consistent with the local character of the energy transfer process.

On the statistical aspects of sunspot number time series and its association with the summer-monsoon rainfall over India

NASA Astrophysics Data System (ADS)

Chattopadhyay, Surajit; Chattopadhyay, Goutami

The present paper reports studies on the association between the mean annual sunspot numbers and the summer monsoon rainfall over India. The cross correlations have been studied. After Box-Cox transformation, the time spectral analysis has been executed and it has been found that both of the time series have an important spectrum at the fifth harmonic. An artificial neural network (ANN) model has been developed on the data series averaged continuously by five years and the neural network could establish a predictor-predict and relationship between the sunspot numbers and the mean yearly summer monsoon rainfall over India.

Time correlation functions of simple liquids: A new insight on the underlying dynamical processes

NASA Astrophysics Data System (ADS)

Garberoglio, Giovanni; Vallauri, Renzo; Bafile, Ubaldo

2018-05-01

Extensive molecular dynamics simulations of liquid sodium have been carried out to evaluate correlation functions of several dynamical quantities. We report the results of a novel analysis of the longitudinal and transverse correlation functions obtained by evaluating directly their self- and distinct contributions at different wavevectors k. It is easily recognized that the self-contribution remains close to its k → 0 limit, which turns out to be exactly the autocorrelation function of the single particle velocity. The wavevector dependence of the longitudinal and transverse spectra and their self- and distinct parts is also presented. By making use of the decomposition of the velocity autocorrelation spectrum in terms of longitudinal and transverse parts, our analysis is able to recognize the effect of different dynamical processes in different frequency ranges.

First-order reactant in homogeneous turbulence before the final period of decay. [contaminant fluctuations in chemical reaction

NASA Technical Reports Server (NTRS)

Kumar, P.; Patel, S. R.

1974-01-01

A method is described for studying theoretically the concentration fluctuations of a dilute contaminate undergoing a first-order chemical reaction. The method is based on Deissler's (1958) theory for homogeneous turbulence for times before the final period, and it follows the approach used by Loeffler and Deissler (1961) to study temperature fluctuations in homogeneous turbulence. Four-point correlation equations are obtained; it is assumed that terms containing fifth-order correlation are very small in comparison with those containing fourth-order correlations, and can therefore be neglected. A spectrum equation is obtained in a form which can be solved numerically, yielding the decay law for the concentration fluctuations in homogeneous turbulence for the period much before the final period of decay.

Thickness of the Magnetic Crust of Mars from Magneto-Spectral Analysis

NASA Technical Reports Server (NTRS)

Voorhies, Coerte V.

2006-01-01

Previous analysis of the magnetic spectrum of Mars showed only a crustal source field. The observational spectrum was fairly well fitted by the spectrum expected from random dipolar sources scattered on a spherical shell about 46 plus or minus 10 km below Mars' 3389.5 km mean radius. This de-correlation depth overestimates the typical depth of extended magnetized structures, and so was judged closer to mean source layer thickness than twice its value. To better estimate the thickness of the magnetic crust of Mars, six different magnetic spectra were fitted with the theoretical spectrum expected from a novel, bimodal distribution of magnetic sources. This theoretical spectrum represents both compact and extended, laterally correlated sources, so source shell depth is doubled to obtain layer thickness. The typical magnetic crustal thickness is put at 47.8 plus or minus 8.2 km. The extended sources are enormous, typically 650 km across, and account for over half the magnetic energy at low degrees. How did such vast regions form?

Assessment of 48 Stock markets using adaptive multifractal approach

NASA Astrophysics Data System (ADS)

Ferreira, Paulo; Dionísio, Andreia; Movahed, S. M. S.

2017-11-01

In this paper, Stock market comovements are examined using cointegration, Granger causality tests and nonlinear approaches in context of mutual information and correlations. Since underlying data sets are affected by non-stationarities and trends, we also apply Adaptive Multifractal Detrended Fluctuation Analysis (AMF-DFA) and Adaptive Multifractal Detrended Cross-Correlation Analysis (AMF-DXA). We find only 170 pair of Stock markets cointegrated, and according to the Granger causality and mutual information, we realize that the strongest relations lies between emerging markets, and between emerging and frontier markets. According to scaling exponent given by AMF-DFA, h(q = 2) > 1, we find that all underlying data sets belong to non-stationary process. According to Efficient Market Hypothesis (EMH), only 8 markets are classified in uncorrelated processes at 2 σ confidence interval. 6 Stock markets belong to anti-correlated class and dominant part of markets has memory in corresponding daily index prices during January 1995 to February 2014. New-Zealand with H = 0 . 457 ± 0 . 004 and Jordan with H = 0 . 602 ± 0 . 006 are far from EMH. The nature of cross-correlation exponents based on AMF-DXA is almost multifractal for all pair of Stock markets. The empirical relation, Hxy ≤ [Hxx +Hyy ] / 2, is confirmed. Mentioned relation for q > 0 is also satisfied while for q < 0 there is a deviation from this relation confirming behavior of markets for small fluctuations is affected by contribution of major pair. For larger fluctuations, the cross-correlation contains information from both local (internal) and global (external) conditions. Width of singularity spectrum for auto-correlation and cross-correlation are Δαxx ∈ [ 0 . 304 , 0 . 905 ] and Δαxy ∈ [ 0 . 246 , 1 . 178 ] , respectively. The wide range of singularity spectrum for cross-correlation confirms that the bilateral relation between Stock markets is more complex. The value of σDCCA indicates that all pairs of stock market studied in this time interval belong to cross-correlated processes.

Deficits in anticipatory but not consummatory pleasure in people with recent-onset schizophrenia spectrum disorders

PubMed Central

Mote, Jasmine; Minzenberg, Michael; Carter, C. S.; Kring, Ann M.

2014-01-01

The majority of studies examining self-reported anticipatory and consummatory pleasure in schizophrenia, as measured on the Temporal Experience of Pleasure Scale (TEPS), has been conducted on chronically ill people with the disorder. In this study, people with a recent-onset schizophrenia spectrum diagnosis (first psychotic episode within one year of study participation) (n=88) and people without a schizophrenia spectrum diagnosis (n=66) were administered the TEPS. People with a schizophrenia spectrum diagnosis reported significantly lower scores of anticipatory, but not consummatory, pleasure on the TEPS compared to the control group. TEPS anticipatory pleasure scores were also significantly, negatively correlated with negative symptoms, but neither TEPS anticipatory nor consummatory pleasure scores were significantly correlated with functioning measures. Our results replicate previous findings with chronically ill people with schizophrenia on the TEPS. PMID:25139112

Inhibin B and anti-Müllerian hormone/Müllerian-inhibiting substance may contribute to the male bias in autism.

PubMed

Pankhurst, M W; McLennan, I S

2012-08-14

The autistic spectrum disorders have a significant male bias in incidence, which is unexplained. The Sertoli cells of the immature testes secrete supra-adult levels of Müllerian-inhibiting substance/anti-Müllerian hormone (AMH) and inhibin B (InhB), with both hormones being putative regulators of brain development. We report here, that 82 boys with an autism spectrum disorder have normal levels of InhB and AMH. However, the boys' level of InhB correlated with their autism diagnostic interview-revised (ADI-R) scores for the social interaction (R=0.29, P=0.009, N=82) and communication domains (R=0.29, P=0.022, N=63), and with the number of autistic traits the boys exhibited (R=0.34 and 0.27, respectively). The strengths of the abovementioned correlates were stronger in the boys with milder autism (R=0.42 and 0.50, respectively), with AMH exhibiting a significant negative correlation to the ADI-R score in these boys (R=-0.44 and R=-0.39, respectively). Neither hormone correlated to the incidence of stereotyped and repetitive behaviours. This suggests that the male bias in the autistic spectrum has multiple determinants, which modulate the effects of an otherwise non-dimorphic pathology. Furthermore, AMH and InhB have opposing effects on the SMAD1/5/8 pathway, and opposing correlates to autistic traits, implicating the SMAD pathways as a putative point of molecular convergence for the autistic spectrum.

Band selection method based on spectrum difference in targets of interest in hyperspectral imagery

NASA Astrophysics Data System (ADS)

Zhang, Xiaohan; Yang, Guang; Yang, Yongbo; Huang, Junhua

2016-10-01

While hyperspectral data shares rich spectrum information, it has numbers of bands with high correlation coefficients, causing great data redundancy. A reasonable band selection is important for subsequent processing. Bands with large amount of information and low correlation should be selected. On this basis, according to the needs of target detection applications, the spectral characteristics of the objects of interest are taken into consideration in this paper, and a new method based on spectrum difference is proposed. Firstly, according to the spectrum differences of targets of interest, a difference matrix which represents the different spectral reflectance of different targets in different bands is structured. By setting a threshold, the bands satisfying the conditions would be left, constituting a subset of bands. Then, the correlation coefficients between bands are calculated and correlation matrix is given. According to the size of the correlation coefficient, the bands can be set into several groups. At last, the conception of normalized variance is used on behalf of the information content of each band. The bands are sorted by the value of its normalized variance. Set needing number of bands, and the optimum band combination solution can be get by these three steps. This method retains the greatest degree of difference between the target of interest and is easy to achieve by computer automatically. Besides, false color image synthesis experiment is carried out using the bands selected by this method as well as other 3 methods to show the performance of method in this paper.

Dynamic characterization of a damaged beam using empirical mode decomposition and Hilbert spectrum method

NASA Astrophysics Data System (ADS)

Chang, Chih-Chen; Poon, Chun-Wing

2004-07-01

Recently, the empirical mode decomposition (EMD) in combination with the Hilbert spectrum method has been proposed to identify the dynamic characteristics of linear structures. In this study, this EMD and Hilbert spectrum method is used to analyze the dynamic characteristics of a damaged reinforced concrete (RC) beam in the laboratory. The RC beam is 4m long with a cross section of 200mm X 250mm. The beam is sequentially subjected to a concentrated load of different magnitudes at the mid-span to produce different degrees of damage. An impact load is applied around the mid-span to excite the beam. Responses of the beam are recorded by four accelerometers. Results indicate that the EMD and Hilbert spectrum method can reveal the variation of the dynamic characteristics in the time domain. These results are also compared with those obtained using the Fourier analysis. In general, it is found that the two sets of results correlate quite well in terms of mode counts and frequency values. Some differences, however, can be seen in the damping values, which perhaps can be attributed to the linear assumption of the Fourier transform.

Effect of correlated decay on fault-tolerant quantum computation

NASA Astrophysics Data System (ADS)

Lemberger, B.; Yavuz, D. D.

2017-12-01

We analyze noise in the circuit model of quantum computers when the qubits are coupled to a common bosonic bath and discuss the possible failure of scalability of quantum computation. Specifically, we investigate correlated (super-radiant) decay between the qubit energy levels from a two- or three-dimensional array of qubits without imposing any restrictions on the size of the sample. We first show that regardless of how the spacing between the qubits compares with the emission wavelength, correlated decay produces errors outside the applicability of the threshold theorem. This is because the sum of the norms of the two-body interaction Hamiltonians (which can be viewed as the upper bound on the single-qubit error) that decoheres each qubit scales with the total number of qubits and is unbounded. We then discuss two related results: (1) We show that the actual error (instead of the upper bound) on each qubit scales with the number of qubits. As a result, in the limit of large number of qubits in the computer, N →∞ , correlated decay causes each qubit in the computer to decohere in ever shorter time scales. (2) We find the complete eigenvalue spectrum of the exchange Hamiltonian that causes correlated decay in the same limit. We show that the spread of the eigenvalue distribution grows faster with N compared to the spectrum of the unperturbed system Hamiltonian. As a result, as N →∞ , quantum evolution becomes completely dominated by the noise due to correlated decay. These results argue that scalable quantum computing may not be possible in the circuit model in a two- or three- dimensional geometry when the qubits are coupled to a common bosonic bath.

Correlation between Cognition and Function across the Spectrum of Alzheimer's Disease.

PubMed

Liu-Seifert, H; Siemers, E; Selzler, K; Sundell, K; Aisen, P; Cummings, J; Raskin, J; Mohs, R

2016-01-01

Both cognitive and functional deterioration are characteristic of the clinical progression of Alzheimer's disease (AD). To systematically assess correlations between widely used measures of cognition and function across the spectrum of AD. Spearman rank correlations were calculated for cognitive and functional measures across datasets from various AD patient populations. Post-hoc analysis from existing databases. Pooled data from placebo-treated patients with mild (MMSE score ≥20 and ≤26) and moderate (MMSE score ≥16 and ≤19) AD dementia from two Phase 3 solanezumab (EXPEDITION/2) and two semagecesatat (IDENTITY/2) studies and normal, late mild cognitive impairment (LMCI) and mild AD patients from the Alzheimer's Disease Neuroimaging Initiative 2-Grand Opportunity (ADNI-2/GO). Intervention (if any): Placebo (EXPEDITION/2 and IDENTITY/2 subjects). Cognitive and functional abilities were measured in all datasets. Data were collected at baseline and every three months for 18 months in EXPEDITION and IDENTITY studies; and at baseline, 6, 12, and 24 months in the ADNI dataset. The relationship of cognition and function became stronger over time as AD patients progressed from preclinical to moderate dementia disease stages, with the magnitude of correlations dependent on disease stage and the complexity of functional task. The correlations were minimal in the normal control population, but became stronger with disease progression. This analysis found that measures of cognition and function become more strongly correlated with disease progression from preclinical to moderate dementia across multiple datasets. These findings improve the understanding of the relationship between cognitive and functional clinical measures during the course of AD progression and how cognition and function measures relate to each other in AD clinical trials.

Functional mixed effects spectral analysis

PubMed Central

KRAFTY, ROBERT T.; HALL, MARTICA; GUO, WENSHENG

2011-01-01

SUMMARY In many experiments, time series data can be collected from multiple units and multiple time series segments can be collected from the same unit. This article introduces a mixed effects Cramér spectral representation which can be used to model the effects of design covariates on the second-order power spectrum while accounting for potential correlations among the time series segments collected from the same unit. The transfer function is composed of a deterministic component to account for the population-average effects and a random component to account for the unit-specific deviations. The resulting log-spectrum has a functional mixed effects representation where both the fixed effects and random effects are functions in the frequency domain. It is shown that, when the replicate-specific spectra are smooth, the log-periodograms converge to a functional mixed effects model. A data-driven iterative estimation procedure is offered for the periodic smoothing spline estimation of the fixed effects, penalized estimation of the functional covariance of the random effects, and unit-specific random effects prediction via the best linear unbiased predictor. PMID:26855437

Multifractal analysis and the NYHA index

NASA Astrophysics Data System (ADS)

Muñoz-Diosdado, A.; Ramírez-Hernández, L.; Aguilar-Molina, A. M.; Zamora-Justo, J. A.; Gutiérrez-Calleja, R. A.; Virgilio-González, C. D.

2014-11-01

We did multifractal analysis of heartbeat interval time series of healthy persons and patients with congestive heart failure (CHF). To analyze circadian rhythm variations we analyzed time series of 24 hours records and segments of six hours when the subject is asleep and segments of six hours when is awake. A decrease in the multifractality degree occurs in the heartbeat interval time series of CHF patients. This multifractality loss is associated with the width reduction of the spectrum and the complexity loss of the signal. Multifractal spectra of healthy persons are right skewed, but the spectra of CHF patients tend to be symmetrical and in some cases are left skewed. To determine the therapy for CHF patients, cardiologists use an index proposed by the NYHA (New York Heart Association). There is a correlation between this index and the multifractal analysis parameters, i.e. while higher is the NYHA index the width of the multifractal spectrum is lower and it is also more symmetrical. In contrast, patients with NYHA index equal to 1 have multifractal parameters similar to those of healthy subjects.

Optical chaos and hybrid WDM/TDM based large capacity quasi-distributed sensing network with real-time fiber fault monitoring.

PubMed

Luo, Yiyang; Xia, Li; Xu, Zhilin; Yu, Can; Sun, Qizhen; Li, Wei; Huang, Di; Liu, Deming

2015-02-09

An optical chaos and hybrid wavelength division multiplexing/time division multiplexing (WDM/TDM) based large capacity quasi-distributed sensing network with real-time fiber fault monitoring is proposed. Chirped fiber Bragg grating (CFBG) intensity demodulation is adopted to improve the dynamic range of the measurements. Compared with the traditional sensing interrogation methods in time, radio frequency and optical wavelength domains, the measurand sensing and the precise locating of the proposed sensing network can be simultaneously interrogated by the relative amplitude change (RAC) and the time delay of the correlation peak in the cross-correlation spectrum. Assisted with the WDM/TDM technology, hundreds of sensing units could be potentially multiplexed in the multiple sensing fiber lines. Based on the proof-of-concept experiment for axial strain measurement with three sensing fiber lines, the strain sensitivity up to 0.14% RAC/με and the precise locating of the sensors are achieved. Significantly, real-time fiber fault monitoring in the three sensing fiber lines is also implemented with a spatial resolution of 2.8 cm.

Simulation of random road microprofile based on specified correlation function

NASA Astrophysics Data System (ADS)

Rykov, S. P.; Rykova, O. A.; Koval, V. S.; Vlasov, V. G.; Fedotov, K. V.

2018-03-01

The paper aims to develop a numerical simulation method and an algorithm for a random microprofile of special roads based on the specified correlation function. The paper used methods of correlation, spectrum and numerical analysis. It proves that the transfer function of the generating filter for known expressions of spectrum input and output filter characteristics can be calculated using a theorem on nonnegative and fractional rational factorization and integral transformation. The model of the random function equivalent of the real road surface microprofile enables us to assess springing system parameters and identify ranges of variations.

A Comparison of WISC-IV and SB-5 Intelligence Scores in Adolescents with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Baum, Katherine T.; Shear, Paula K.; Howe, Steven R.; Bishop, Somer L.

2015-01-01

In autism spectrum disorders, results of cognitive testing inform clinical care, theories of neurodevelopment, and research design. The Wechsler Intelligence Scale for Children and the Stanford-Binet are commonly used in autism spectrum disorder evaluations and scores from these tests have been shown to be highly correlated in typically developing…

Source Correlated Prompt Neutron Activation Analysis for Material Identification and Localization

NASA Astrophysics Data System (ADS)

Canion, Bonnie; McConchie, Seth; Landsberger, Sheldon

2017-07-01

This paper investigates the energy spectrum of photon signatures from an associated particle imaging deuterium tritium (API-DT) neutron generator interrogating shielded uranium. The goal is to investigate if signatures within the energy spectrum could be used to indirectly characterize shielded uranium when the neutron signature is attenuated. By utilizing the correlated neutron cone associated with each pixel of the API-DT neutron generator, certain materials can be identified and located via source correlated spectrometry of prompt neutron activation gamma rays. An investigation is done to determine if fission neutrons induce a significant enough signature within the prompt neutron-induced gamma-ray energy spectrum in shielding material to be useful for indirect nuclear material characterization. The signature deriving from the induced fission neutrons interacting with the shielding material was slightly elevated in polyethylene-shielding depleted uranium (DU), but was more evident in some characteristic peaks from the aluminum shielding surrounding DU.

A novel fast phase correlation algorithm for peak wavelength detection of Fiber Bragg Grating sensors.

PubMed

Lamberti, A; Vanlanduit, S; De Pauw, B; Berghmans, F

2014-03-24

Fiber Bragg Gratings (FBGs) can be used as sensors for strain, temperature and pressure measurements. For this purpose, the ability to determine the Bragg peak wavelength with adequate wavelength resolution and accuracy is essential. However, conventional peak detection techniques, such as the maximum detection algorithm, can yield inaccurate and imprecise results, especially when the Signal to Noise Ratio (SNR) and the wavelength resolution are poor. Other techniques, such as the cross-correlation demodulation algorithm are more precise and accurate but require a considerable higher computational effort. To overcome these problems, we developed a novel fast phase correlation (FPC) peak detection algorithm, which computes the wavelength shift in the reflected spectrum of a FBG sensor. This paper analyzes the performance of the FPC algorithm for different values of the SNR and wavelength resolution. Using simulations and experiments, we compared the FPC with the maximum detection and cross-correlation algorithms. The FPC method demonstrated a detection precision and accuracy comparable with those of cross-correlation demodulation and considerably higher than those obtained with the maximum detection technique. Additionally, FPC showed to be about 50 times faster than the cross-correlation. It is therefore a promising tool for future implementation in real-time systems or in embedded hardware intended for FBG sensor interrogation.

1/f noise: diffusive systems and music

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voss, R.F.

1975-11-01

Measurements of the 1/f voltage noise in continuous metal films are reported. At room temperature, samples of pure metals and bismuth (with a carrier density smaller by 10/sup 5/) of similar volume had comparable noise. The results suggest that the noise arises from equilibrium temperature fluctuations modulating the resistance. Spatial correlation of the noise implied that the fluctuations obey a diffusion equation. The empirical inclusion of an explicit 1/f region and appropriate normalization lead to excellent agreement with the measured noise. If the fluctuations are assumed to be spatially correlated, the diffusion equation can yield an extended 1/f region inmore » the power spectrum. The temperature response of a sample to delta and step function power inputs is shown to have the same shape as the autocorrelation function for uncorrelated and correlated temperature fluctuations, respectively. The spectrum obtained from the cosine transform of the measured step function response is in excellent agreement with the measured 1/f voltage noise spectrum. Spatially correlated equilibrium temperature fluctuations are not the dominant source of 1/f noise in semiconductors and metal films. However, the agreement between the low-frequency spectrum of fluctuations in the mean-square Johnson noise voltage and the resistance fluctuation spectrum measured in the presence of a current demonstrates that in these systems the 1/f noise is also due to equilibrium resistance fluctuations. Loudness fluctuations in music and speech and pitch fluctuations in music also show the 1/f behavior. 1/f noise sources, consequently, are demonstrated to be the natural choice for stochastic composition. 26 figures, 1 table. (auth)« less

Parent- and Self-Reported Social Skills Importance in Autism Spectrum Disorder.

PubMed

Rankin, James A; Weber, Rebecca J; Kang, Erin; Lerner, Matthew D

2016-01-01

While social skills are commonly assessed in autism spectrum disorder (ASD), little is known about individuals' and families' beliefs regarding importance of these skills. Seventy-four parents and their children with ASD rated social skills importance and severity, as well as ASD-specific deficit severity. Parents and youth rated social skills as important overall; however, parents reported assertion and self-control to be more important than their children did. Severity and importance did not correlate overall. However, parent-report of responsibility deficits and importance were positively correlated, while youth-report of assertiveness deficits and importance were negatively correlated. Finally, ASD-specific social deficits were positively correlated with parent reported importance, but negatively correlated with child reported importance. Social skills importance ratings merit consideration in ASD assessment.

Rapid modelling of the redshift-space power spectrum multipoles for a masked density field

NASA Astrophysics Data System (ADS)

Wilson, M. J.; Peacock, J. A.; Taylor, A. N.; de la Torre, S.

2017-01-01

In this work, we reformulate the forward modelling of the redshift-space power spectrum multipole moments for a masked density field, as encountered in galaxy redshift surveys. Exploiting the symmetries of the redshift-space correlation function, we provide a masked-field generalization of the Hankel transform relation between the multipole moments in real and Fourier space. Using this result, we detail how a likelihood analysis requiring computation for a broad range of desired P(k) models may be executed 103-104 times faster than with other common approaches, together with significant gains in spectral resolution. We present a concrete application to the complex angular geometry of the VIMOS Public Extragalactic Redshift Survey PDR-1 release and discuss the validity of this technique for finite-angle surveys.

Response approach to the squeezed-limit bispectrum: application to the correlation of quasar and Lyman-α forest power spectrum

DOE PAGES

Chiang, Chi-Ting; Cieplak, Agnieszka M.; Schmidt, Fabian; ...

2017-06-12

We present the squeezed-limit bispectrum, which is generated by nonlinear gravitational evolution as well as inflationary physics, measures the correlation of three wavenumbers, in the configuration where one wavenumber is much smaller than the other two. Since the squeezed-limit bispectrum encodes the impact of a large-scale fluctuation on the small-scale power spectrum, it can be understood as how the small-scale power spectrum ``responds'' to the large-scale fluctuation. Viewed in this way, the squeezed-limit bispectrum can be calculated using the response approach even in the cases which do not submit to perturbative treatment. To illustrate this point, we apply this approachmore » to the cross-correlation between the large-scale quasar density field and small-scale Lyman-α forest flux power spectrum. In particular, using separate universe simulations which implement changes in the large-scale density, velocity gradient, and primordial power spectrum amplitude, we measure how the Lyman-α forest flux power spectrum responds to the local, long-wavelength quasar overdensity, and equivalently their squeezed-limit bispectrum. We perform a Fisher forecast for the ability of future experiments to constrain local non-Gaussianity using the bispectrum of quasars and the Lyman-α forest. Combining with quasar and Lyman-α forest power spectra to constrain the biases, we find that for DESI the expected 1-σ constraint is err[f NL]~60. Ability for DESI to measure f NL through this channel is limited primarily by the aliasing and instrumental noise of the Lyman-α forest flux power spectrum. Lastly, the combination of response approach and separate universe simulations provides a novel technique to explore the constraints from the squeezed-limit bispectrum between different observables.« less

Response approach to the squeezed-limit bispectrum: application to the correlation of quasar and Lyman-α forest power spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiang, Chi-Ting; Cieplak, Agnieszka M.; Schmidt, Fabian

We present the squeezed-limit bispectrum, which is generated by nonlinear gravitational evolution as well as inflationary physics, measures the correlation of three wavenumbers, in the configuration where one wavenumber is much smaller than the other two. Since the squeezed-limit bispectrum encodes the impact of a large-scale fluctuation on the small-scale power spectrum, it can be understood as how the small-scale power spectrum ``responds'' to the large-scale fluctuation. Viewed in this way, the squeezed-limit bispectrum can be calculated using the response approach even in the cases which do not submit to perturbative treatment. To illustrate this point, we apply this approachmore » to the cross-correlation between the large-scale quasar density field and small-scale Lyman-α forest flux power spectrum. In particular, using separate universe simulations which implement changes in the large-scale density, velocity gradient, and primordial power spectrum amplitude, we measure how the Lyman-α forest flux power spectrum responds to the local, long-wavelength quasar overdensity, and equivalently their squeezed-limit bispectrum. We perform a Fisher forecast for the ability of future experiments to constrain local non-Gaussianity using the bispectrum of quasars and the Lyman-α forest. Combining with quasar and Lyman-α forest power spectra to constrain the biases, we find that for DESI the expected 1-σ constraint is err[f NL]~60. Ability for DESI to measure f NL through this channel is limited primarily by the aliasing and instrumental noise of the Lyman-α forest flux power spectrum. Lastly, the combination of response approach and separate universe simulations provides a novel technique to explore the constraints from the squeezed-limit bispectrum between different observables.« less

Response approach to the squeezed-limit bispectrum: application to the correlation of quasar and Lyman-α forest power spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiang, Chi-Ting; Cieplak, Agnieszka M.; Slosar, Anže

The squeezed-limit bispectrum, which is generated by nonlinear gravitational evolution as well as inflationary physics, measures the correlation of three wavenumbers, in the configuration where one wavenumber is much smaller than the other two. Since the squeezed-limit bispectrum encodes the impact of a large-scale fluctuation on the small-scale power spectrum, it can be understood as how the small-scale power spectrum ''responds'' to the large-scale fluctuation. Viewed in this way, the squeezed-limit bispectrum can be calculated using the response approach even in the cases which do not submit to perturbative treatment. To illustrate this point, we apply this approach to themore » cross-correlation between the large-scale quasar density field and small-scale Lyman-α forest flux power spectrum. In particular, using separate universe simulations which implement changes in the large-scale density, velocity gradient, and primordial power spectrum amplitude, we measure how the Lyman-α forest flux power spectrum responds to the local, long-wavelength quasar overdensity, and equivalently their squeezed-limit bispectrum. We perform a Fisher forecast for the ability of future experiments to constrain local non-Gaussianity using the bispectrum of quasars and the Lyman-α forest. Combining with quasar and Lyman-α forest power spectra to constrain the biases, we find that for DESI the expected 1−σ constraint is err[ f {sub NL}]∼60. Ability for DESI to measure f {sub NL} through this channel is limited primarily by the aliasing and instrumental noise of the Lyman-α forest flux power spectrum. The combination of response approach and separate universe simulations provides a novel technique to explore the constraints from the squeezed-limit bispectrum between different observables.« less

Spectral and Timing States in Black Hole Binaries

NASA Astrophysics Data System (ADS)

Wilms, J.

Results on the long term variability of galactic black hole candidates are reviewed. I mainly present the results of a > 2 year long campaign with RXTE to monitor the canonical soft state black hole candidates LMC X-1 and LMC X-3 using monthly observations. These observations are presented within the context of the RXTE-ASM long term quasi-periodic variability on timescales of about 150d. For LMC X-3, times of low ASM count rate are correlated with a significant hardening of the X-ray spectrum. The observation with the lowest flux during the whole monitoring campaign can be modeled with a simple γ=1.7 power law -- a hard state spectrum. Since these spectral hardenings occur on the 150 d timescale it is probable that they are associated with periodic changes in the accretion rate. Possible causes for this behavior are discussed, e.g. a wind driven limit-cycle or long-term variability of the donor star.

Spectral Entropy Based Neuronal Network Synchronization Analysis Based on Microelectrode Array Measurements

PubMed Central

Kapucu, Fikret E.; Välkki, Inkeri; Mikkonen, Jarno E.; Leone, Chiara; Lenk, Kerstin; Tanskanen, Jarno M. A.; Hyttinen, Jari A. K.

2016-01-01

Synchrony and asynchrony are essential aspects of the functioning of interconnected neuronal cells and networks. New information on neuronal synchronization can be expected to aid in understanding these systems. Synchronization provides insight in the functional connectivity and the spatial distribution of the information processing in the networks. Synchronization is generally studied with time domain analysis of neuronal events, or using direct frequency spectrum analysis, e.g., in specific frequency bands. However, these methods have their pitfalls. Thus, we have previously proposed a method to analyze temporal changes in the complexity of the frequency of signals originating from different network regions. The method is based on the correlation of time varying spectral entropies (SEs). SE assesses the regularity, or complexity, of a time series by quantifying the uniformity of the frequency spectrum distribution. It has been previously employed, e.g., in electroencephalogram analysis. Here, we revisit our correlated spectral entropy method (CorSE), providing evidence of its justification, usability, and benefits. Here, CorSE is assessed with simulations and in vitro microelectrode array (MEA) data. CorSE is first demonstrated with a specifically tailored toy simulation to illustrate how it can identify synchronized populations. To provide a form of validation, the method was tested with simulated data from integrate-and-fire model based computational neuronal networks. To demonstrate the analysis of real data, CorSE was applied on in vitro MEA data measured from rat cortical cell cultures, and the results were compared with three known event based synchronization measures. Finally, we show the usability by tracking the development of networks in dissociated mouse cortical cell cultures. The results show that temporal correlations in frequency spectrum distributions reflect the network relations of neuronal populations. In the simulated data, CorSE unraveled the synchronizations. With the real in vitro MEA data, CorSE produced biologically plausible results. Since CorSE analyses continuous data, it is not affected by possibly poor spike or other event detection quality. We conclude that CorSE can reveal neuronal network synchronization based on in vitro MEA field potential measurements. CorSE is expected to be equally applicable also in the analysis of corresponding in vivo and ex vivo data analysis. PMID:27803660

Modulational Instability of Cylindrical and Spherical NLS Equations. Statistical Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grecu, A. T.; Grecu, D.; Visinescu, Anca

2010-01-21

The modulational (Benjamin-Feir) instability for cylindrical and spherical NLS equations (c/s NLS equations) is studied using a statistical approach (SAMI). A kinetic equation for a two-point correlation function is written and analyzed using the Wigner-Moyal transform. The linear stability of the Fourier transform of the two-point correlation function is studied and an implicit integral form for the dispersion relation is found. This is solved for different expressions of the initial spectrum (delta-spectrum, Lorentzian, Gaussian), and in the case of a Lorentzian spectrum the total growth of the instability is calculated. The similarities and differences with the usual one-dimensional NLS equationmore » are emphasized.« less

Tumor necrosis factor-alpha expression in peripheral blood mononuclear cells correlates with early childhood social interaction in autism spectrum disorder.

PubMed

Makinodan, Manabu; Iwata, Keiko; Ikawa, Daisuke; Yamashita, Yasunori; Yamamuro, Kazuhiko; Toritsuka, Michihiro; Kimoto, Sohei; Okumura, Kazuki; Yamauchi, Takahira; Yoshino, Hiroki; Tsujii, Masatsugu; Sugiyama, Toshiro; Tsuchiya, Kenji; Mori, Norio; Matsuzaki, Hideo; Kishimoto, Toshifumi

2017-03-01

Autism spectrum disorder is a neurodevelopmental disorder characterized by impaired social interaction, poor communication skills, and repetitive/restrictive behaviors. Elevated blood levels of pro-inflammatory cytokines have been reported in subjects with autism spectrum disorder. On the other hand, early childhood adverse experience also increases blood levels of these cytokines. Since social experience of children with autism spectrum disorder is generally unlike to typically developing children, we hypothesized that social interaction during childhood contribute to pro-inflammatory cytokine expression in subjects with autism spectrum disorder. We compared revised Autism Diagnostic Interview scores and expression levels of pro-inflammatory cytokines in peripheral blood mononuclear cells of subjects with autism spectrum disorder (n = 30). The score of domain A on the revised Autism Diagnostic Interview, indicating social interaction impairment in early childhood, was negatively correlated with tumor necrosis factor-α mRNA expression level in peripheral blood mononuclear cells but not interleukin-1β or -6. Consistently, tumor necrosis factor-α mRNA expression was markedly low in subjects with autism spectrum disorder compared to typically developing children who presumably experienced the regular levels of social interaction. These findings suggest that the low blood levels of tumor necrosis factor-α mRNA in subjects with autism spectrum disorder might be due to impaired social interaction in early childhood. Copyright © 2016 Elsevier Ltd. All rights reserved.

Multichannel-Sensing Scheduling and Transmission-Energy Optimizing in Cognitive Radio Networks with Energy Harvesting.

PubMed

Hoan, Tran-Nhut-Khai; Hiep, Vu-Van; Koo, In-Soo

2016-03-31

This paper considers cognitive radio networks (CRNs) utilizing multiple time-slotted primary channels in which cognitive users (CUs) are powered by energy harvesters. The CUs are under the consideration that hardware constraints on radio devices only allow them to sense and transmit on one channel at a time. For a scenario where the arrival of harvested energy packets and the battery capacity are finite, we propose a scheme to optimize (i) the channel-sensing schedule (consisting of finding the optimal action (silent or active) and sensing order of channels) and (ii) the optimal transmission energy set corresponding to the channels in the sensing order for the operation of the CU in order to maximize the expected throughput of the CRN over multiple time slots. Frequency-switching delay, energy-switching cost, correlation in spectrum occupancy across time and frequency and errors in spectrum sensing are also considered in this work. The performance of the proposed scheme is evaluated via simulation. The simulation results show that the throughput of the proposed scheme is greatly improved, in comparison to related schemes in the literature. The collision ratio on the primary channels is also investigated.

3D seismic data de-noising and reconstruction using Multichannel Time Slice Singular Spectrum Analysis

NASA Astrophysics Data System (ADS)

Rekapalli, Rajesh; Tiwari, R. K.; Sen, Mrinal K.; Vedanti, Nimisha

2017-05-01

Noises and data gaps complicate the seismic data processing and subsequently cause difficulties in the geological interpretation. We discuss a recent development and application of the Multi-channel Time Slice Singular Spectrum Analysis (MTSSSA) for 3D seismic data de-noising in time domain. In addition, L1 norm based simultaneous data gap filling of 3D seismic data using MTSSSA also discussed. We discriminated the noises from single individual time slices of 3D volumes by analyzing Eigen triplets of the trajectory matrix. We first tested the efficacy of the method on 3D synthetic seismic data contaminated with noise and then applied to the post stack seismic reflection data acquired from the Sleipner CO2 storage site (pre and post CO2 injection) from Norway. Our analysis suggests that the MTSSSA algorithm is efficient to enhance the S/N for better identification of amplitude anomalies along with simultaneous data gap filling. The bright spots identified in the de-noised data indicate upward migration of CO2 towards the top of the Utsira formation. The reflections identified applying MTSSSA to pre and post injection data correlate well with the geology of the Southern Viking Graben (SVG).

Hard Fusion Based Spectrum Sensing over Mobile Fading Channels in Cognitive Vehicular Networks

PubMed Central

Hao, Li; Ni, Dadong; Tran, Quang Thanh

2018-01-01

An explosive growth in vehicular wireless applications gives rise to spectrum resource starvation. Cognitive radio has been used in vehicular networks to mitigate the impending spectrum starvation problem by allowing vehicles to fully exploit spectrum opportunities unoccupied by licensed users. Efficient and effective detection of licensed user is a critical issue to realize cognitive radio applications. However, spectrum sensing in vehicular environments is a very challenging task due to vehicle mobility. For instance, vehicle mobility has a large effect on the wireless channel, thereby impacting the detection performance of spectrum sensing. Thus, gargantuan efforts have been made in order to analyze the fading properties of mobile radio channel in vehicular environments. Indeed, numerous studies have demonstrated that the wireless channel in vehicular environments can be characterized by a temporally correlated Rayleigh fading. In this paper, we focus on energy detection for spectrum sensing and a counting rule for cooperative sensing based on Neyman-Pearson criteria. Further, we go into the effect of the sensing and reporting channel conditions on the sensing performance under the temporally correlated Rayleigh channel. For local and cooperative sensing, we derive some alternative expressions for the average probability of misdetection. The pertinent numerical and simulating results are provided to further validate our theoretical analyses under a variety of scenarios. PMID:29415452

Deficits in anticipatory but not consummatory pleasure in people with recent-onset schizophrenia spectrum disorders.

PubMed

Mote, Jasmine; Minzenberg, Michael J; Carter, C S; Kring, Ann M

2014-10-01

The majority of studies examining self-reported anticipatory and consummatory pleasure in schizophrenia, as measured on the Temporal Experience of Pleasure Scale (TEPS), have been conducted on chronically ill people with the disorder. In this study, people with a recent-onset schizophrenia spectrum diagnosis (first psychotic episode within one year of study participation) (n=88) and people without a schizophrenia spectrum diagnosis (n=66) were administered the TEPS. People with a schizophrenia spectrum diagnosis reported significantly lower scores of anticipatory, but not consummatory, pleasure on the TEPS compared to the control group. TEPS anticipatory pleasure scores were also significantly, negatively correlated with negative symptoms, but neither TEPS anticipatory nor consummatory pleasure scores were significantly correlated with functioning measures. Our results replicate previous findings with chronically ill people with schizophrenia on the TEPS. Copyright © 2014 Elsevier B.V. All rights reserved.

[Achievement of the noninvasive measurement for human blood glucose with NIR diffusion reflectance spectrum method].

PubMed

Zhang, Hong-yan; Ding, Dong; Song, Li-qiang; Gu, Lin-na; Yang, Peng; Tang, Yu-guo

2005-06-01

The noninvasive measurement of human blood glucose was achieved with NIR diffusion reflectance spectrum method. The thumb fingertip NIR diffusion reflectance spectra of six different age healthy volunteers were collected using Nexus-870 and its NIR fiber port smart accessory. The test was implemented with changing the blood glucose concentration for the limosis and satiation of every volunteer. The calibration model was set up using PLS method with the smoothing, baseline correction and first derivatives pretreatment spectrum in the 7500-8500 cm(-1) region for single volunteer, the same age combination and that of different age. When the spectrum was obtained, the actual blood glucose value of every spectrun sample was demarcated using ultraviolet spectrophotometer. The correlation between the calibration value and true value for single volunteer is better than that for the combination of volunteers, the correlative coefficients are all over 0.90471, RMSECs are all less than 0.171.

The Performance of a PN Spread Spectrum Receiver Preceded by an Adaptive Interference Suppression Filter.

DTIC Science & Technology

1982-12-01

Sequence dj Estimate of the Desired Signal DEL Sampling Time Interval DS Direct Sequence c Sufficient Statistic E/T Signal Power Erfc Complimentary Error...Namely, a white Gaussian noise (WGN) generator was added. Also, a statistical subroutine was added in order to assess performance improvement at the...reference code and then passed through a correlation detector whose output is the sufficient 1 statistic , e . Using a threshold device and the sufficient

Multi-client quantum key distribution using wavelength division multiplexing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grice, Warren P; Bennink, Ryan S; Earl, Dennis Duncan

Quantum Key Distribution (QKD) exploits the rules of quantum mechanics to generate and securely distribute a random sequence of bits to two spatially separated clients. Typically a QKD system can support only a single pair of clients at a time, and so a separate quantum link is required for every pair of users. We overcome this limitation with the design and characterization of a multi-client entangled-photon QKD system with the capacity for up to 100 clients simultaneously. The time-bin entangled QKD system includes a broadband down-conversion source with two unique features that enable the multi-user capability. First, the photons aremore » emitted across a very large portion of the telecom spectrum. Second, and more importantly, the photons are strongly correlated in their energy degree of freedom. Using standard wavelength division multiplexing (WDM) hardware, the photons can be routed to different parties on a quantum communication network, while the strong spectral correlations ensure that each client is linked only to the client receiving the conjugate wavelength. In this way, a single down-conversion source can support dozens of channels simultaneously--and to the extent that the WDM hardware can send different spectral channels to different clients, the system can support multiple client pairings. We will describe the design and characterization of the down-conversion source, as well as the client stations, which must be tunable across the emission spectrum.« less

A Smoothing Technique for the Multifractal Analysis of a Medium Voltage Feeders Electric Current

NASA Astrophysics Data System (ADS)

de Santis, Enrico; Sadeghian, Alireza; Rizzi, Antonello

2017-12-01

The current paper presents a data-driven detrending technique allowing to smooth complex sinusoidal trends from a real-world electric load time series before applying the Detrended Multifractal Fluctuation Analysis (MFDFA). The algorithm we call Smoothed Sort and Cut Fourier Detrending (SSC-FD) is based on a suitable smoothing of high power periodicities operating directly in the Fourier spectrum through a polynomial fitting technique of the DFT. The main aim consists of disambiguating the characteristic slow varying periodicities, that can impair the MFDFA analysis, from the residual signal in order to study its correlation properties. The algorithm performances are evaluated on a simple benchmark test consisting of a persistent series where the Hurst exponent is known, with superimposed ten sinusoidal harmonics. Moreover, the behavior of the algorithm parameters is assessed computing the MFDFA on the well-known sunspot data, whose correlation characteristics are reported in literature. In both cases, the SSC-FD method eliminates the apparent crossover induced by the synthetic and natural periodicities. Results are compared with some existing detrending methods within the MFDFA paradigm. Finally, a study of the multifractal characteristics of the electric load time series detrendended by the SSC-FD algorithm is provided, showing a strong persistent behavior and an appreciable amplitude of the multifractal spectrum that allows to conclude that the series at hand has multifractal characteristics.

Signatures of pairing in the magnetic excitation spectrum of strongly correlated two-leg ladders [Signatures of pairing in the magnetic excitation spectrum of strongly correlated ladders

DOE PAGES

Nocera, Alberto; Patel, Niravkumar D.; Dagotto, Elbio R.; ...

2017-11-13

Magnetic interactions are widely believed to play a crucial role in the microscopic mechanism leading to high critical temperature superconductivity. It is therefore important to study the signatures of pairing in the magnetic excitation spectrum of simple models known to show unconventional superconducting tendencies. Using the density matrix renormalization group technique, we calculate the dynamical spin structure factor S(k,ω) of a generalized t–U–J Hubbard model away from half filling in a two-leg ladder geometry. The addition of J enhances pairing tendencies. We analyze quantitatively the signatures of pairing in the magnetic excitation spectra. We found that the superconducting pair-correlation strength,more » that can be estimated independently from ground state properties, is closely correlated with the integrated low-energy magnetic spectral weight in the vicinity of (π,π). In this wave-vector region, robust spin incommensurate features develop with increasing doping. The branch of the spectrum with rung direction wave vector k rung=0 does not change substantially with doping where pairing dominates and thus plays a minor role. As a result, we discuss the implications of our results for neutron scattering experiments, where the spin excitation dynamics of hole-doped quasi-one-dimensional magnetic materials can be measured and also address implications for recent resonant inelastic x-ray scattering experiments.« less

Signatures of pairing in the magnetic excitation spectrum of strongly correlated two-leg ladders [Signatures of pairing in the magnetic excitation spectrum of strongly correlated ladders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nocera, Alberto; Patel, Niravkumar D.; Dagotto, Elbio R.

Magnetic interactions are widely believed to play a crucial role in the microscopic mechanism leading to high critical temperature superconductivity. It is therefore important to study the signatures of pairing in the magnetic excitation spectrum of simple models known to show unconventional superconducting tendencies. Using the density matrix renormalization group technique, we calculate the dynamical spin structure factor S(k,ω) of a generalized t–U–J Hubbard model away from half filling in a two-leg ladder geometry. The addition of J enhances pairing tendencies. We analyze quantitatively the signatures of pairing in the magnetic excitation spectra. We found that the superconducting pair-correlation strength,more » that can be estimated independently from ground state properties, is closely correlated with the integrated low-energy magnetic spectral weight in the vicinity of (π,π). In this wave-vector region, robust spin incommensurate features develop with increasing doping. The branch of the spectrum with rung direction wave vector k rung=0 does not change substantially with doping where pairing dominates and thus plays a minor role. As a result, we discuss the implications of our results for neutron scattering experiments, where the spin excitation dynamics of hole-doped quasi-one-dimensional magnetic materials can be measured and also address implications for recent resonant inelastic x-ray scattering experiments.« less

Many-Body Quantum Chaos: Analytic Connection to Random Matrix Theory

NASA Astrophysics Data System (ADS)

Kos, Pavel; Ljubotina, Marko; Prosen, Tomaž

2018-04-01

A key goal of quantum chaos is to establish a relationship between widely observed universal spectral fluctuations of clean quantum systems and random matrix theory (RMT). Most prominent features of such RMT behavior with respect to a random spectrum, both encompassed in the spectral pair correlation function, are statistical suppression of small level spacings (correlation hole) and enhanced stiffness of the spectrum at large spectral ranges. For single-particle systems with fully chaotic classical counterparts, the problem has been partly solved by Berry [Proc. R. Soc. A 400, 229 (1985), 10.1098/rspa.1985.0078] within the so-called diagonal approximation of semiclassical periodic-orbit sums, while the derivation of the full RMT spectral form factor K (t ) (Fourier transform of the spectral pair correlation function) from semiclassics has been completed by Müller et al. [Phys. Rev. Lett. 93, 014103 (2004), 10.1103/PhysRevLett.93.014103]. In recent years, the questions of long-time dynamics at high energies, for which the full many-body energy spectrum becomes relevant, are coming to the forefront even for simple many-body quantum systems, such as locally interacting spin chains. Such systems display two universal types of behaviour which are termed the "many-body localized phase" and "ergodic phase." In the ergodic phase, the spectral fluctuations are excellently described by RMT, even for very simple interactions and in the absence of any external source of disorder. Here we provide a clear theoretical explanation for these observations. We compute K (t ) in the leading two orders in t and show its agreement with RMT for nonintegrable, time-reversal invariant many-body systems without classical counterparts, a generic example of which are Ising spin-1 /2 models in a periodically kicking transverse field. In particular, we relate K (t ) to partition functions of a class of twisted classical Ising models on a ring of size t ; hence, the leading-order RMT behavior K (t )≃2 t is a consequence of translation and reflection symmetry of the Ising partition function.

Behavioral and Emotional Problems in High-Functioning Girls and Boys with Autism Spectrum Disorders: Parents' Reports and Adolescents' Self-Reports

ERIC Educational Resources Information Center

Pisula, Ewa; Pudlo, Monika; Slowinska, Monika; Kawa, Rafal; Strzaska, Magdalena; Banasiak, Anna; Wolanczyk, Tomasz

2017-01-01

The purpose of this study was to investigate sex differences in behavioral and emotional problems in high-functioning girls and boys with autism spectrum disorder. The results obtained by adolescents with autism spectrum disorder were compared with those of typically developing girls and boys. Correlations between parents' and adolescents' ratings…

[A Study of the Relationship Among Genetic Distances, NIR Spectra Distances, and NIR-Based Identification Model Performance of the Seeds of Maize Iinbred Lines].

PubMed

Liu, Xu; Jia, Shi-qiang; Wang, Chun-ying; Liu, Zhe; Gu, Jian-cheng; Zhai, Wei; Li, Shao-ming; Zhang, Xiao-dong; Zhu, De-hai; Huang, Hua-jun; An, Dong

2015-09-01

This paper explored the relationship among genetic distances, NIR spectra distances and NIR-based identification model performance of the seeds of maize inbred lines. Using 3 groups (total 15 pairs) of maize inbred lines whose genetic distaches are different as experimental materials, we calculates the genetic distance between these seeds with SSR markers and uses Euclidean distance between distributed center points of maize NIR spectrum in the PCA space as the distances of NIR spectrum. BPR method is used to build identification model of inbred lines and the identification accuracy is used as a measure of model identification performance. The results showed that, the correlation of genetic distance and spectra distancesis 0.9868, and it has a correlation of 0.9110 with the identification accuracy, which is highly correlated. This means near-Infrared spectrum of seedscan reflect genetic relationship of maize inbred lines. The smaller the genetic distance, the smaller the distance of spectrum, the poorer ability of model to identify. In practical application, near infrared spectrum analysis technology has the potential to be used to analyze maize inbred genetic relations, contributing much to genetic breeding, identification of species, purity sorting and so on. What's more, when creating a NIR-based identification model, the impact of the maize inbred lines which have closer genetic relationship should be fully considered.

Breast abscess after nipple piercing: sonographic findings with clinical correlation.

PubMed

Leibman, A Jill; Misra, Monika; Castaldi, Maria

2011-09-01

The purpose of this series was to review the spectrum of clinical and sonographic features associated with infection after nipple piercing. Between 2002 and 2010, 6 patients presented to our breast center with a breast abscess after nipple piercing. A retrospective analysis of the imaging findings was performed with clinical and pathologic correlation. Patients with breast infections after nipple piercing tend to be young, and the timing since piercing varies from 2 weeks to 17 months. Sonography showed a complex or hypoechoic mass in 5 of 6 patients. Treatment of breast abscesses included surgical incision and drainage, percutaneous drainage, and antibiotic therapy. Surgical evacuation is commonly performed; however, sonographically guided aspiration may be an appropriate management strategy.

Spectral analysis of pair-correlation bandwidth: application to cell biology images.

PubMed

Binder, Benjamin J; Simpson, Matthew J

2015-02-01

Images from cell biology experiments often indicate the presence of cell clustering, which can provide insight into the mechanisms driving the collective cell behaviour. Pair-correlation functions provide quantitative information about the presence, or absence, of clustering in a spatial distribution of cells. This is because the pair-correlation function describes the ratio of the abundance of pairs of cells, separated by a particular distance, relative to a randomly distributed reference population. Pair-correlation functions are often presented as a kernel density estimate where the frequency of pairs of objects are grouped using a particular bandwidth (or bin width), Δ>0. The choice of bandwidth has a dramatic impact: choosing Δ too large produces a pair-correlation function that contains insufficient information, whereas choosing Δ too small produces a pair-correlation signal dominated by fluctuations. Presently, there is little guidance available regarding how to make an objective choice of Δ. We present a new technique to choose Δ by analysing the power spectrum of the discrete Fourier transform of the pair-correlation function. Using synthetic simulation data, we confirm that our approach allows us to objectively choose Δ such that the appropriately binned pair-correlation function captures known features in uniform and clustered synthetic images. We also apply our technique to images from two different cell biology assays. The first assay corresponds to an approximately uniform distribution of cells, while the second assay involves a time series of images of a cell population which forms aggregates over time. The appropriately binned pair-correlation function allows us to make quantitative inferences about the average aggregate size, as well as quantifying how the average aggregate size changes with time.

Prevalence and Correlates of Bullying Involvement among Adolescents with an Autism Spectrum Disorder

PubMed Central

Sterzing, Paul R.; Shattuck, Paul T.; Narendorf, Sarah C.; Wagner, Mary; Cooper, Benjamin P.

2012-01-01

Objectives Produce nationally representative estimates for rates of bullying involvement among adolescents with an autism spectrum disorder, compare population estimates to adolescents with other developmental disabilities, and identify social ecological correlates of bullying involvement Design Nationally representative surveys from 2001 Setting United States Participants Parents of adolescents with an autism spectrum disorder, principals of the schools they attended, and staff members most familiar with their school programs Main Exposure Autism spectrum disorders Outcomes Measures: Bullying involvement (parent report of victimization, perpetration, and victimization/perpetration within the last school year) Results The prevalence rates of bullying involvement for adolescents with an autism spectrum disorder were 46.3% (victimization), 14.8% (perpetration), and 8.9% (victimization/perpetration). Victimization was related to having a non-Hispanic ethnic identity, attention-deficit/hyperactivity disorder, lower social skills, some form of conversational ability, and more classes in general education. Correlates of perpetration included being White, having attention-deficit/hyperactivity disorder, and getting together with friends at least once a week. Victimization/perpetration was associated with being White, non-Hispanic ethnicity, attention-deficit/hyperactivity disorder, and getting together with friends at least once a week Conclusions School-based bullying interventions need to target the core deficits of autism (conversational ability, social skills) and comorbid conditions (attention-deficit/hyperactivity disorder). Future bullying interventions also need to address the higher rates of victimization that occur in general education settings by increasing social integration into protective peer groups and increasing the empathy and social skills of typically developing students toward their peers with an autism spectrum disorder. PMID:22945284

Dynamic cross-correlations between entangled biofilaments as they diffuse

PubMed Central

Tsang, Boyce; Dell, Zachary E.; Jiang, Lingxiang; Schweizer, Kenneth S.; Granick, Steve

2017-01-01

Entanglement in polymer and biological physics involves a state in which linear interthreaded macromolecules in isotropic liquids diffuse in a spatially anisotropic manner beyond a characteristic mesoscopic time and length scale (tube diameter). The physical reason is that linear macromolecules become transiently localized in directions transverse to their backbone but diffuse with relative ease parallel to it. Within the resulting broad spectrum of relaxation times there is an extended period before the longest relaxation time when filaments occupy a time-averaged cylindrical space of near-constant density. Here we show its implication with experiments based on fluorescence tracking of dilutely labeled macromolecules. The entangled pairs of aqueous F-actin biofilaments diffuse with separation-dependent dynamic cross-correlations that exceed those expected from continuum hydrodynamics up to strikingly large spatial distances of ≈15 µm, which is more than 104 times the size of the solvent water molecules in which they are dissolved, and is more than 50 times the dynamic tube diameter, but is almost equal to the filament length. Modeling this entangled system as a collection of rigid rods, we present a statistical mechanical theory that predicts these long-range dynamic correlations as an emergent consequence of an effective long-range interpolymer repulsion due to the de Gennes correlation hole, which is a combined consequence of chain connectivity and uncrossability. The key physical assumption needed to make theory and experiment agree is that solutions of entangled biofilaments localized in tubes that are effectively dynamically incompressible over the relevant intermediate time and length scales. PMID:28283664

Frequency-Modulation Correlation Spectrometer

NASA Technical Reports Server (NTRS)

Margolis, J. S.; Martonchik, J. V.

1985-01-01

New type of correlation spectrometer eliminates need to shift between two cells, one empty and one containing reference gas. Electrooptical phase modulator sinusoidally shift frequencies of sample transmission spectrum.

Dynamical Correlation In Some Liquid Alkaline Earth Metals Near Melting

NASA Astrophysics Data System (ADS)

Thakore, B. Y.; Suthar, P. H.; Khambholja, S. G.; Gajjar, P. N.; Jani, A. R.

2010-12-01

The study of dynamical variables: velocity autocorrelation function (VACF) and power spectrum of liquid alkaline earth metals (Ca, Sr, and Ba) have been presented based on the static harmonic well approximation. The effective interatomic potential for liquid metals is computed using our well recognized model potential with the exchange correlation functions due to Hartree, Taylor, Ichimaru and Utsumi, Farid et al. and Sarkar et al. It is observed that the VACF computed using Sarkar et al. gives the good agreement with available molecular dynamics simulation (MD) results [Phys Rev. B 62, 14818 (2000)]. The shoulder of the power spectrum depends upon the type of local field correlation function used.

Deficits in motor abilities and developmental fractionation of imitation performance in high-functioning autism spectrum disorders.

PubMed

Biscaldi, Monica; Rauh, Reinhold; Irion, Lisa; Jung, Nikolai H; Mall, Volker; Fleischhaker, Christian; Klein, Christoph

2014-07-01

The co-occurrence of motor and imitation disabilities often characterises the spectrum of deficits seen in patients with autism spectrum disorders (ASD). Whether these seemingly separate deficits are inter-related and whether, in particular, motor deficits contribute to the expression of imitation deficits is the topic of the present study and was investigated by comparing these deficits' cross-sectional developmental trajectories. To that end, different components of motor performance assessed in the Zurich Neuromotor Assessment and imitation abilities for facial movements and non-meaningful gestures were tested in 70 subjects (aged 6-29 years), including 36 patients with high-functioning ASD and 34 age-matched typically developed (TD) participants. The results show robust deficits in probands with ASD in timed motor performance and in the quality of movement, which are all independent of age, with one exception. Only diadochokinesis improves moderately with increasing age in ASD probands. Imitation of facial movements and of non-meaningful hand, finger, hand finger gestures not related to social context or tool use is also impaired in ASD subjects, but in contrast to motor performance this deficit overall improves with age. A general imitation factor, extracted from the highly inter-correlated imitation tests, is differentially correlated with components of neuromotor performance in ASD and TD participants. By developmentally fractionating developmentally stable motor deficits from developmentally dynamic imitation deficits, we infer that imitation deficits are primarily cognitive in nature.

The Oral Narrative Comprehension and Production Abilities of Verbal Preschoolers on the Autism Spectrum.

PubMed

Westerveld, Marleen F; Roberts, Jacqueline M A

2017-10-05

This study described the oral narrative comprehension and production skills of verbal preschool-age children on the autism spectrum and investigated correlations between oral narrative ability and norm-referenced language test performance. Twenty-nine preschool-age children (aged 4;0-5;9 years;months) with autism, who obtained an age-equivalent score of at least 36 months on the expressive communication subscale of the Vineland Adaptive Behavior Scales-Second Edition (Sparrow, Cicchetti, & Balla, 2005), participated. Children listened to an unfamiliar fictional narrative and answered comprehension questions afterward. After listening to the narrative a second time, children were asked to retell the narrative without picture support. Narratives were transcribed and analyzed for length, semantic diversity, grammatical complexity and accuracy, intelligibility, inclusion of critical events, and narrative stage. All children participated in the comprehension task, and 19 children produced an analyzable narrative retell. Compared with published data on typically developing children, significant difficulties were observed in narrative comprehension, intelligibility, and grammatical accuracy. Most of the children told descriptive or action sequences, with only 1 child producing an abbreviated episode. Significant positive correlations were found (a) between performance on the Peabody Picture Vocabulary Test-Fourth Edition (Dunn & Dunn, 2007) and semantic diversity and narrative comprehension and (b) between parent-reported receptive communication competence (Vineland Adaptive Behavior Scales-Second Edition) and narrative comprehension. This study provides preliminary evidence of specific difficulties in oral narrative comprehension and production skills in verbal preschoolers on the autism spectrum.

The relation between face-emotion recognition and social function in adolescents with autism spectrum disorders: A case control study.

PubMed

Høyland, Anne Lise; Nærland, Terje; Engstrøm, Morten; Lydersen, Stian; Andreassen, Ole Andreas

2017-01-01

An altered processing of emotions may contribute to a reduced ability for social interaction and communication in autism spectrum disorder, ASD. We investigated how face-emotion recognition in ASD is different from typically developing across adolescent age groups. Fifty adolescents diagnosed with ASD and 49 typically developing (age 12-21 years) were included. The ASD diagnosis was underpinned by parent-rated Social Communication Questionnaire. We used a cued GO/ NOGO task with pictures of facial expressions and recorded reaction time, intra-individual variability of reaction time and omissions/commissions. The Social Responsiveness Scale was used as a measure of social function. Analyses were conducted for the whole group and for young (< 16 years) and old (≥ 16 years) age groups. We found no significant differences in any task measures between the whole group of typically developing and ASD and no significant correlations with the Social Responsiveness Scale. However, there was a non-significant tendency for longer reaction time in the young group with ASD (p = 0.099). The Social Responsiveness Scale correlated positively with reaction time (r = 0.30, p = 0.032) and intra-individual variability in reaction time (r = 0.29, p = 0.037) in the young group and in contrast, negatively in the old group (r = -0.23, p = 0.13; r = -0.38, p = 0.011, respectively) giving significant age group interactions for both reaction time (p = 0.008) and intra-individual variability in reaction time (p = 0.001). Our findings suggest an age-dependent association between emotion recognition and severity of social problems indicating a delayed development of emotional understanding in ASD. It also points towards alterations in top-down attention control in the ASD group. This suggests novel disease-related features that should be investigated in more details in experimental settings.

Differential Attention to Faces in Infant Siblings of Children with Autism Spectrum Disorder and Associations with Later Social and Language Ability.

PubMed

Wagner, Jennifer B; Luyster, Rhiannon J; Moustapha, Hana; Tager-Flusberg, Helen; Nelson, Charles A

2018-01-01

A growing body of literature has begun to explore social attention in infant siblings of children with autism spectrum disorder (ASD) with hopes of identifying early differences that are associated with later ASD or other aspects of development. The present study used eye-tracking to familiar (mother) and unfamiliar (stranger) faces in two groups of 6-month-old infants: infants with no family history of ASD (low-risk controls; LRC), and infants at high risk for ASD (HRA), by virtue of having an older sibling with ASD. HRA infants were further characterized based on autism classification at 24 months or older as HRA- (HRA without an ASD outcome) or HRA+ (HRA with an ASD outcome). For time scanning faces overall, HRA+ and LRC showed similar patterns of attention, and this was significantly greater than in HRA-. When examining duration of time spent on eyes and mouth, all infants spent more time on eyes than mouth, but HRA+ showed the greatest amount of time looking at these regions, followed by LRC, then HRA-. LRC showed a positive association between 6-month attention to eyes and 18-month social-communicative behavior, while HRA- showed a negative association between attention to eyes at 6 months and expressive language at 18 months (all correlations controlled for non-verbal IQ; HRA- correlations held with and without the inclusion of the small sample of HRA+). Differences found in face scanning at 6 months, as well as associations with social communication at 18 months, point to potential variation in the developmental significance of early social attention in children at low and high risk for ASD.

Making the Transition from Diagnosis to Treatment-Planning: Validity, Reliability and Factor Structure of the Autism Spectrum Disorder Behaviour Checklist

ERIC Educational Resources Information Center

Bitsika, Vicki; Sharpley, Christopher F.

2018-01-01

The validity, reliability and factor structure of the Autism Spectrum Disorder Behaviour Checklist-Revised (ASDBC-R) were measured in a sample of 140 boys with Autism Spectrum Disorder (ASD) aged between 6 and 18 years. Internal consistency (Cronbach's alpha) was satisfactory and the ASDBC-R significantly correlated with the Social Responsiveness…

Multiscale analysis of heart rate dynamics: entropy and time irreversibility measures.

PubMed

Costa, Madalena D; Peng, Chung-Kang; Goldberger, Ary L

2008-06-01

Cardiovascular signals are largely analyzed using traditional time and frequency domain measures. However, such measures fail to account for important properties related to multiscale organization and non-equilibrium dynamics. The complementary role of conventional signal analysis methods and emerging multiscale techniques, is, therefore, an important frontier area of investigation. The key finding of this presentation is that two recently developed multiscale computational tools--multiscale entropy and multiscale time irreversibility--are able to extract information from cardiac interbeat interval time series not contained in traditional methods based on mean, variance or Fourier spectrum (two-point correlation) techniques. These new methods, with careful attention to their limitations, may be useful in diagnostics, risk stratification and detection of toxicity of cardiac drugs.

Multiscale Analysis of Heart Rate Dynamics: Entropy and Time Irreversibility Measures

PubMed Central

Peng, Chung-Kang; Goldberger, Ary L.

2016-01-01

Cardiovascular signals are largely analyzed using traditional time and frequency domain measures. However, such measures fail to account for important properties related to multiscale organization and nonequilibrium dynamics. The complementary role of conventional signal analysis methods and emerging multiscale techniques, is, therefore, an important frontier area of investigation. The key finding of this presentation is that two recently developed multiscale computational tools— multiscale entropy and multiscale time irreversibility—are able to extract information from cardiac interbeat interval time series not contained in traditional methods based on mean, variance or Fourier spectrum (two-point correlation) techniques. These new methods, with careful attention to their limitations, may be useful in diagnostics, risk stratification and detection of toxicity of cardiac drugs. PMID:18172763

False Detection of Dangerous and Netural Substances in Commonly Used Materials by Means of the Standard THz Time Domain Spectroscopy

NASA Astrophysics Data System (ADS)

Trofimov, V. A.; Varentsova, S. A.

2016-04-01

Essential limitations of the standard THz Time Domain Spectroscopy (TDS), which lead to false detection of dangerous and neutral substances in commonly used materials, are demonstrated using the physical experiment with chocolate under real conditions as well as with semiconductors under laboratory conditions. To overcome this disadvantage, we propose using the time-dependent spectrum of the THz pulse, transmitted through or reflected from a substance. For quality assessment of the standard substance absorption frequency presence in the signal under analysis, we use time-dependent integral correlation criteria. The influence of aperture placed in front of the sample on spectral properties of silicon wafers with different resistivity is demonstrated as well.

Stopping dynamics of ions passing through correlated honeycomb clusters

NASA Astrophysics Data System (ADS)

Balzer, Karsten; Schlünzen, Niclas; Bonitz, Michael

2016-12-01

A combined nonequilibrium Green functions-Ehrenfest dynamics approach is developed that allows for a time-dependent study of the energy loss of a charged particle penetrating a strongly correlated system at zero and finite temperatures. Numerical results are presented for finite inhomogeneous two-dimensional Fermi-Hubbard models, where the many-electron dynamics in the target are treated fully quantum mechanically and the motion of the projectile is treated classically. The simulations are based on the solution of the two-time Dyson (Keldysh-Kadanoff-Baym) equations using the second-order Born, third-order, and T -matrix approximations of the self-energy. As application, we consider protons and helium nuclei with a kinetic energy between 1 and 500 keV/u passing through planar fragments of the two-dimensional honeycomb lattice and, in particular, examine the influence of electron-electron correlations on the energy exchange between projectile and electron system. We investigate the time dependence of the projectile's kinetic energy (stopping power), the electron density, the double occupancy, and the photoemission spectrum. Finally, we show that, for a suitable choice of the Hubbard model parameters, the results for the stopping power are in fair agreement with ab initio simulations for particle irradiation of single-layer graphene.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adichtchev, S. V.; Malinovsky, V. K.; Surovtsev, N. V., E-mail: lab21@iae.nsk.su

Low-frequency (down to 30 GHz) inelastic light scattering is studied in a multicomponent glass ZBLAN (ZrF{sub 4}-BaF{sub 2}-LaF{sub 3}-AlF{sub 3}-NaF) in a wide temperature range. The contributions of the THz vibrational spectrum (boson peak) and of the fast relaxation are extracted and analyzed. It is shown that the fast relaxation spectrum is described by a distribution of relaxation times leading to a power-law ν{sup α} dependence in the frequency range 30–300 GHz. Temperature dependence of α(T) is well described by the Gilroy-Phillips model, while the integrated intensity of the fast relaxation increases significantly with the temperature. This feature distinguishes themore » fast relaxation in ZBLAN from the case of most single-component glasses. Thermodynamic and kinetic fragility indexes are significantly different for the ZBLAN glass. The correlations between the boson peak intensity, elastic moduli, and fragility index, found earlier for single-component glasses, are fulfilled for the thermodynamic fragility index of ZBLAN. In contrast, the correlation between the fast relaxation intensity at T{sub g} and the fragility holds better for the kinetic fragility index of ZBLAN. We propose that thermodynamic and kinetic fragilities reflect different aspects of glassy dynamics in the case of glass formers with the complex chemical composition and structure topology: the former correlates with the elastic properties and the boson peak, the latter with the relaxation.« less

Simulation of spatially evolving turbulence and the applicability of Taylor's hypothesis in compressible flow

NASA Technical Reports Server (NTRS)

Lee, Sangsan; Lele, Sanjiva K.; Moin, Parviz

1992-01-01

For the numerical simulation of inhomogeneous turbulent flows, a method is developed for generating stochastic inflow boundary conditions with a prescribed power spectrum. Turbulence statistics from spatial simulations using this method with a low fluctuation Mach number are in excellent agreement with the experimental data, which validates the procedure. Turbulence statistics from spatial simulations are also compared to those from temporal simulations using Taylor's hypothesis. Statistics such as turbulence intensity, vorticity, and velocity derivative skewness compare favorably with the temporal simulation. However, the statistics of dilatation show a significant departure from those obtained in the temporal simulation. To directly check the applicability of Taylor's hypothesis, space-time correlations of fluctuations in velocity, vorticity, and dilatation are investigated. Convection velocities based on vorticity and velocity fluctuations are computed as functions of the spatial and temporal separations. The profile of the space-time correlation of dilatation fluctuations is explained via a wave propagation model.

Geographic smoothing of solar PV: Results from Gujarat

DOE PAGES

Klima, Kelly; Apt, Jay

2015-09-24

We examine the potential for geographic smoothing of solar photovoltaic (PV) electricity generation using 13 months of observed power production from utility-scale plants in Gujarat, India. To our knowledge, this is the first published analysis of geographic smoothing of solar PV using actual generation data at high time resolution from utility-scale solar PV plants. We use geographic correlation and Fourier transform estimates of the power spectral density (PSD) to characterize the observed variability of operating solar PV plants as a function of time scale. Most plants show a spectrum that is linear in the log–log domain at high frequencies f,more » ranging from f -1.23 to f -1.56 (slopes of -1.23 and -1.56), thus exhibiting more relative variability at high frequencies than exhibited by wind plants. PSDs for large PV plants have a steeper slope than those for small plants, hence more smoothing at short time scales. Interconnecting 20 Gujarat plants yields a f -1.66 spectrum, reducing fluctuations at frequencies corresponding to 6 h and 1 h by 23% and 45%, respectively. Half of this smoothing can be obtained through connecting 4-5 plants; reaching marginal improvement of 1% per added plant occurs at 12-14 plants. The largest plant (322 MW) showed an f -1.76 spectrum. Furthermore, this suggests that in Gujarat the potential for smoothing is limited to that obtained by one large plant.« less

Time-based and event-based prospective memory in autism spectrum disorder: the roles of executive function and theory of mind, and time-estimation.

PubMed

Williams, David; Boucher, Jill; Lind, Sophie; Jarrold, Christopher

2013-07-01

Prospective memory (remembering to carry out an action in the future) has been studied relatively little in ASD. We explored time-based (carry out an action at a pre-specified time) and event-based (carry out an action upon the occurrence of a pre-specified event) prospective memory, as well as possible cognitive correlates, among 21 intellectually high-functioning children with ASD, and 21 age- and IQ-matched neurotypical comparison children. We found impaired time-based, but undiminished event-based, prospective memory among children with ASD. In the ASD group, time-based prospective memory performance was associated significantly with diminished theory of mind, but not with diminished cognitive flexibility. There was no evidence that time-estimation ability contributed to time-based prospective memory impairment in ASD.

Motor demands impact speed of information processing in Autism Spectrum Disorders

PubMed Central

Kenworthy, Lauren; Yerys, Benjamin E.; Weinblatt, Rachel; Abrams, Danielle N.; Wallace, Gregory L.

2015-01-01

Objective The apparent contradiction between preserved or even enhanced perceptual processing speed on inspection time tasks in autism spectrum disorders (ASD) and impaired performance on complex processing speed tasks that require motor output (e.g. Wechsler Processing Speed Index) has not yet been systematically investigated. This study investigates whether adding motor output demands to an inspection time task impairs ASD performance compared to that of typically developing control (TDC) children. Method The performance of children with ASD (n=28; mean FSIQ=115) and TDC (n=25; mean FSIQ=122) children was compared on processing speed tasks with increasing motor demand. Correlations were run between ASD task performance and Autism Diagnostic Observation Schedule (ADOS) Communication scores. Results Performance by the ASD and TDC groups on a simple perceptual processing speed task with minimal motor demand was equivalent, though it diverged (ASD worse than TDC) on two tasks with the same stimuli, but increased motor output demands. ASD performance on the moderate but not the high speeded motor output demand task was negatively correlated with ADOS communication symptoms. Conclusions These data address the apparent contradiction between preserved inspection time in the context of slowed “processing speed” in ASD. They show that processing speed is preserved when motor demands are minimized, but that increased motor output demands interfere with the ability to act on perceptual processing of simple stimuli. Reducing motor demands (e.g. through the use of computers) may increase the capacity of people with ASD to demonstrate good perceptual processing in a variety of educational, vocational and social settings. PMID:23937483

Low-amplitude clustering in low-redshift 21-cm intensity maps cross-correlated with 2dF galaxy densities

NASA Astrophysics Data System (ADS)

Anderson, C. J.; Luciw, N. J.; Li, Y.-C.; Kuo, C. Y.; Yadav, J.; Masui, K. W.; Chang, T.-C.; Chen, X.; Oppermann, N.; Liao, Y.-W.; Pen, U.-L.; Price, D. C.; Staveley-Smith, L.; Switzer, E. R.; Timbie, P. T.; Wolz, L.

2018-05-01

We report results from 21-cm intensity maps acquired from the Parkes radio telescope and cross-correlated with galaxy maps from the 2dF galaxy survey. The data span the redshift range 0.057 < z < 0.098 and cover approximately 1300 deg2 over two long fields. Cross-correlation is detected at a significance of 5.7 σ. The amplitude of the cross-power spectrum is low relative to the expected dark matter power spectrum, assuming a neutral hydrogen (H I) bias and mass density equal to measurements from the ALFALFA survey. The decrement is pronounced and statistically significant at small scales. At k ˜ 1.5 h Mpc-1, the cross-power spectrum is more than a factor of 6 lower than expected, with a significance of 15.3 σ. This decrement indicates a lack of clustering of neutral hydrogen (H I), a small correlation coefficient between optical galaxies and H I, or some combination of the two. Separating 2dF into red and blue galaxies, we find that red galaxies are much more weakly correlated with H I on k ˜ 1.5 h Mpc-1 scales, suggesting that H I is more associated with blue star-forming galaxies and tends to avoid red galaxies.

A perturbative approach to the redshift space correlation function: beyond the Standard Model

NASA Astrophysics Data System (ADS)

Bose, Benjamin; Koyama, Kazuya

2017-08-01

We extend our previous redshift space power spectrum code to the redshift space correlation function. Here we focus on the Gaussian Streaming Model (GSM). Again, the code accommodates a wide range of modified gravity and dark energy models. For the non-linear real space correlation function used in the GSM we use the Fourier transform of the RegPT 1-loop matter power spectrum. We compare predictions of the GSM for a Vainshtein screened and Chameleon screened model as well as GR. These predictions are compared to the Fourier transform of the Taruya, Nishimichi and Saito (TNS) redshift space power spectrum model which is fit to N-body data. We find very good agreement between the Fourier transform of the TNS model and the GSM predictions, with <= 6% deviations in the first two correlation function multipoles for all models for redshift space separations in 50Mpch <= s <= 180Mpc/h. Excellent agreement is found in the differences between the modified gravity and GR multipole predictions for both approaches to the redshift space correlation function, highlighting their matched ability in picking up deviations from GR. We elucidate the timeliness of such non-standard templates at the dawn of stage-IV surveys and discuss necessary preparations and extensions needed for upcoming high quality data.

Phenomenological analysis of medical time series with regular and stochastic components

NASA Astrophysics Data System (ADS)

Timashev, Serge F.; Polyakov, Yuriy S.

2007-06-01

Flicker-Noise Spectroscopy (FNS), a general approach to the extraction and parameterization of resonant and stochastic components contained in medical time series, is presented. The basic idea of FNS is to treat the correlation links present in sequences of different irregularities, such as spikes, "jumps", and discontinuities in derivatives of different orders, on all levels of the spatiotemporal hierarchy of the system under study as main information carriers. The tools to extract and analyze the information are power spectra and difference moments (structural functions), which complement the information of each other. The structural function stochastic component is formed exclusively by "jumps" of the dynamic variable while the power spectrum stochastic component is formed by both spikes and "jumps" on every level of the hierarchy. The information "passport" characteristics that are determined by fitting the derived expressions to the experimental variations for the stochastic components of power spectra and structural functions are interpreted as the correlation times and parameters that describe the rate of "memory loss" on these correlation time intervals for different irregularities. The number of the extracted parameters is determined by the requirements of the problem under study. Application of this approach to the analysis of tremor velocity signals for a Parkinsonian patient is discussed.

Hawking radiation as tunneling in Schwarzschild anti-de Sitter black hole

NASA Astrophysics Data System (ADS)

Sefiedgar, A. S.; Ashrafinejad, A.

2017-08-01

The Hawking radiation from a (d+1) -dimensional Schwarzschild Anti-de Sitter (SAdS) black hole is investigated within rainbow gravity. Based on the method proposed by Kraus, Parikh and Wilczek, the Hawking radiation is considered as a tunneling process across the horizon. The emission rate of massless particles which are tunneling across the quantum-corrected horizon is calculated. Enforcing the energy conservation law leads to a dynamical geometry. Both the dynamical geometry and the quantum effects of space-time yield some corrections to the emission rate. The corrected radiation spectrum is not purely thermal. The emission rate is related to the changes of modified entropy in rainbow gravity and the corrected thermal spectrum may be consistent with an underlying unitary quantum theory. The correlations between emitted particles are also investigated in order to address the recovery of information.

Isoscalar ππ Scattering and the σ Meson Resonance from QCD.

PubMed

Briceño, Raul A; Dudek, Jozef J; Edwards, Robert G; Wilson, David J

2017-01-13

We present for the first time a determination of the energy dependence of the isoscalar ππ elastic scattering phase shift within a first-principles numerical lattice approach to QCD. Hadronic correlation functions are computed including all required quark propagation diagrams, and from these the discrete spectrum of states in the finite volume defined by the lattice boundary is extracted. From the volume dependence of the spectrum, we obtain the S-wave phase shift up to the KK[over ¯] threshold. Calculations are performed at two values of the u, d quark mass corresponding to m_{π}=236,391  MeV, and the resulting amplitudes are described in terms of a σ meson which evolves from a bound state below the ππ threshold at the heavier quark mass to a broad resonance at the lighter quark mass.

An ultrasonic pseudorandom signal-correlation system

NASA Astrophysics Data System (ADS)

Elias, C. M.

1980-01-01

A working ultrasonic pseudorandom signal-correlation system is described which, unlike ultrasonic random signal-correlation systems, does not require an acoustic delay line. Elimination of the delay line allows faster data acquisition and better range resolution. The system uses two identical shift-register type generators to produce pseudonoise bursts which are subsequences of a 65 535-bit complementary m-sequence. One generator produces the transmitted bursts while the other generates identical reference bursts which start at a variable correlation delay time after the transmitted bursts. The reference bursts are cross-correlated with the received echoes to obtain the approximate impulse response of the transducer/specimen system under test. Range sidelobes are reduced by transmitting and correlating many bursts at a given correlation delay before incrementing the delay. Signal-to-sidelobe ratios of greater than 47 dB have been obtained using this method. Limitations of the system due to sampling constraints and the pseudonoise power spectrum are discussed, and the system design and implementation are outlined. Results of experimental characterization of the system show that the pseudorandom signal-correlation system has approximately the same range resolution as a conventional pulse-echo system but can yield a significant increase in signal-to-noise ratio (SNR).

Maladaptive cognitive appraisals in children with high-functioning autism: associations with fear, anxiety and theory of mind.

PubMed

Sharma, Shilpi; Woolfson, Lisa M; Hunter, Simon C

2014-04-01

Despite the well-documented success of cognitive restructuring techniques in the treatment of anxiety disorders, there is still little clarity on which cognitions underpin fear and anxiety in children with high-functioning autism spectrum disorder. This study examined whether certain cognitive appraisals, known to be associated with fear and anxiety in typically developing groups, may help explain these emotions in children with high-functioning autism spectrum disorder. It also investigated relations between these cognitive appraisals and theory of mind. Appraisals, fear and anxiety were assessed using a vignette approach in 22 children with high-functioning autism spectrum disorders and 22 typically developing children. The two groups differed significantly on all four appraisal types. Anxiety was negatively correlated with future expectancy and positively with problem-focused coping potential in the high-functioning autism spectrum disorder group but was not correlated with appraisals in the typically developing group. The two appraisals associated with fear were emotion-focused coping potential (in the high-functioning autism spectrum disorder group only) and self-accountability (in the typically developing group only). Linear regression analysis found that appraisals of emotion-focused coping potential, problem-focused coping potential and future expectancy were significant predictors of theory-of-mind ability in the high-functioning autism spectrum disorders group. These findings indicate that specific, problematic patterns of appraisal may characterise children with high-functioning autism spectrum disorders.

Improvement of energy efficiency via spectrum optimization of excitation sequence for multichannel simultaneously triggered airborne sonar system

NASA Astrophysics Data System (ADS)

Meng, Qing-Hao; Yao, Zhen-Jing; Peng, Han-Yang

2009-12-01

Both the energy efficiency and correlation characteristics are important in airborne sonar systems to realize multichannel ultrasonic transducers working together. High energy efficiency can increase echo energy and measurement range, and sharp autocorrelation and flat cross correlation can help eliminate cross-talk among multichannel transducers. This paper addresses energy efficiency optimization under the premise that cross-talk between different sonar transducers can be avoided. The nondominated sorting genetic algorithm-II is applied to optimize both the spectrum and correlation characteristics of the excitation sequence. The central idea of the spectrum optimization is to distribute most of the energy of the excitation sequence within the frequency band of the sonar transducer; thus, less energy is filtered out by the transducers. Real experiments show that a sonar system consisting of eight-channel Polaroid 600 series electrostatic transducers excited with 2 ms optimized pulse-position-modulation sequences can work together without cross-talk and can measure distances up to 650 cm with maximal 1% relative error.

Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

NASA Astrophysics Data System (ADS)

Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

2013-08-01

We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester Cdbnd O and diazo Ndbnd N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency-frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single Cdbnd O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

Energy spectrum and electrical conductivity of graphene with a nitrogen impurity

NASA Astrophysics Data System (ADS)

Repetskii, S. P.; Vyshivanaya, I. G.; Skotnikov, V. A.; Yatsenyuk, A. A.

2015-04-01

The electronic structure of graphene with a nitrogen impurity has been studied based on the model of tight binding using exchange-correlation potentials in the density-functional theory. Wave functions of 2 s and 2 p states of neutral noninteracting carbon atoms have been chosen as the basis. When studying the matrix elements of the Hamiltonian, the first three coordination shells have been taken into account. It has been established that the hybridization of electron-energy bands leads to the splitting of the electron energy spectrum near the Fermi level. Due to the overlap of the energy bands, the arising gap behaves as a quasi-gap, in which the density of the electron levels is much lower than in the rest of the spectrum. It has been established that the conductivity of graphene decreases with increasing nitrogen concentration. Since the increase in the nitrogen concentration leads to an increase in the density of states at the Fermi level, the decrease in the conductivity is due to a sharper decrease in the time of relaxation of the electron sates.

Sequential fuzzy diagnosis method for motor roller bearing in variable operating conditions based on vibration analysis.

PubMed

Li, Ke; Ping, Xueliang; Wang, Huaqing; Chen, Peng; Cao, Yi

2013-06-21

A novel intelligent fault diagnosis method for motor roller bearings which operate under unsteady rotating speed and load is proposed in this paper. The pseudo Wigner-Ville distribution (PWVD) and the relative crossing information (RCI) methods are used for extracting the feature spectra from the non-stationary vibration signal measured for condition diagnosis. The RCI is used to automatically extract the feature spectrum from the time-frequency distribution of the vibration signal. The extracted feature spectrum is instantaneous, and not correlated with the rotation speed and load. By using the ant colony optimization (ACO) clustering algorithm, the synthesizing symptom parameters (SSP) for condition diagnosis are obtained. The experimental results shows that the diagnostic sensitivity of the SSP is higher than original symptom parameter (SP), and the SSP can sensitively reflect the characteristics of the feature spectrum for precise condition diagnosis. Finally, a fuzzy diagnosis method based on sequential inference and possibility theory is also proposed, by which the conditions of the machine can be identified sequentially as well.

New Theoretical Estimates of the Contribution of Unresolved Star-Forming Galaxies to the Extragalactic Gamma-Ray Background (EGB) as Measured by EGRET and the Fermi-LAT

NASA Technical Reports Server (NTRS)

Venters, Tonia M.

2011-01-01

We present new theoretical estimates of the contribution of unresolved star-forming galaxies to the extragalactic gamma-ray background (EGB) as measured by EGRET and the Fermi-LAT. We employ several methods for determining the star-forming galaxy contribution the the EGB, including a method positing a correlation between the gamma-ray luminosity of a galaxy and its rate of star formation as calculated from the total infrared luminosity, and a method that makes use of a model of the evolution of the galaxy gas mass with cosmic time. We find that depending on the model, unresolved star-forming galaxies could contribute significantly to the EGB as measured by the Fermi-LAT at energies between approx. 300 MeV and approx. few GeV. However, the overall spectrum of unresolved star-forming galaxies can explain neither the EGRET EGB spectrum at energies between 50 and 200 MeV nor the Fermi-LAT EGB spectrum at energies above approx. few GeV.

Sequential Fuzzy Diagnosis Method for Motor Roller Bearing in Variable Operating Conditions Based on Vibration Analysis

PubMed Central

Li, Ke; Ping, Xueliang; Wang, Huaqing; Chen, Peng; Cao, Yi

2013-01-01

A novel intelligent fault diagnosis method for motor roller bearings which operate under unsteady rotating speed and load is proposed in this paper. The pseudo Wigner-Ville distribution (PWVD) and the relative crossing information (RCI) methods are used for extracting the feature spectra from the non-stationary vibration signal measured for condition diagnosis. The RCI is used to automatically extract the feature spectrum from the time-frequency distribution of the vibration signal. The extracted feature spectrum is instantaneous, and not correlated with the rotation speed and load. By using the ant colony optimization (ACO) clustering algorithm, the synthesizing symptom parameters (SSP) for condition diagnosis are obtained. The experimental results shows that the diagnostic sensitivity of the SSP is higher than original symptom parameter (SP), and the SSP can sensitively reflect the characteristics of the feature spectrum for precise condition diagnosis. Finally, a fuzzy diagnosis method based on sequential inference and possibility theory is also proposed, by which the conditions of the machine can be identified sequentially as well. PMID:23793021

The variations of oxygen emissions in corresponding to Earth's aurora in low latitude region under influence of solar wind dynamics

NASA Astrophysics Data System (ADS)

Jamlongkul, P.; Wannawichian, S.

2017-12-01

Earth's aurora in low latitude region was studied via time variations of oxygen emission spectra, simultaneously with solar wind data. The behavior of spectrum intensity, in corresponding with solar wind condition, could be a trace of aurora in low latitude region including some effects of high energetic auroral particles. Oxygen emission spectral lines were observed by Medium Resolution Echelle Spectrograph (MRES) at 2.4-m diameter telescope at Thai National Observatory, Inthanon Mountain, Chiang Mai, Thailand, during 1-5 LT on 5 and 6 February 2017. The observed spectral lines were calibrated via Dech95 - 2D image processing program and Dech-Fits spectra processing program for spectrum image processing and spectrum wavelength calibration, respectively. The variations of observed intensities each day were compared with solar wind parameters, which are magnitude of IMF (|BIMF|) including IMF in RTN coordinate (BR, BT, BN), ion density (ρ), plasma flow pressure (P), and speed (v). The correlation coefficients between oxygen spectral emissions and different solar wind parameters were found to vary in both positive and negative behaviors.

Price-volume multifractal analysis of the Moroccan stock market

NASA Astrophysics Data System (ADS)

El Alaoui, Marwane

2017-11-01

In this paper, we analyzed price-volume multifractal cross-correlations of Moroccan Stock Exchange. We chose the period from January 1st 2000 to January 20th 2017 to investigate the multifractal behavior of price change and volume change series. Then, we used multifractal detrended cross-correlations analysis method (MF-DCCA) and multifractal detrended fluctuation analysis (MF-DFA) to analyze the series. We computed bivariate generalized Hurst exponent, Rényi exponent and spectrum of singularity for each pair of indices to measure quantitatively cross-correlations. Furthermore, we used detrended cross-correlations coefficient (DCCA) and cross-correlation test (Q(m)) to analyze cross-correlation quantitatively and qualitatively. By analyzing results, we found existence of price-volume multifractal cross-correlations. The spectrum width has a strong multifractal cross-correlation. We remarked that volume change series is anti-persistent when we analyzed the generalized Hurst exponent for all moments q. The cross-correlation test showed the presence of a significant cross-correlation. However, DCCA coefficient had a small positive value, which means that the level of correlation is not very significant. Finally, we analyzed sources of multifractality and their degree of contribution in the series.

Spectroscopy of N,N-dimethylformamide in the VUV and IR regions: Experimental and computational studies

NASA Astrophysics Data System (ADS)

Shastri, Aparna; Das, Asim Kumar; Krishnakumar, Sunanda; Singh, Param Jeet; Raja Sekhar, B. N.

2017-12-01

The electronic absorption spectrum of N,N-dimethylformamide (DMF) is studied in the 45 000-80 000 cm-1 (5.6-9.9 eV) region using synchrotron radiation. The vacuum ultraviolet (VUV) spectrum comprises mostly of Rydberg series of ns, np, and nd types converging to the first two ionization potentials (IPs). Quantum defect values obtained are consistent with excitation of an electron from the highest occupied molecular orbitals localized on nitrogen (4a″) and oxygen (16a'); in addition, the 3s Rydberg transition converging to the third IP (3a″) is observed at 8.95 eV. A reinvestigation of the infrared spectrum of DMF in the 500-4000 cm-1 region with the help of density functional theory (DFT) calculations establishes the planarity of the ground state and leads to revision of several vibrational assignments. Vertical excited state energies and their valence/Rydberg character are predicted using time dependent DFT calculations; excellent correlation is achieved between theoretical results and experimentally observed spectral features. Potential energy curves of the first few excited states give additional insights into the nature of the excited states and their role in photodissociation dynamics. The absorption spectrum of DMF in the region >63 400 cm-1 (7.85 eV) as well as a complete set of spectral assignments in the VUV region (45 000-80 000 cm-1) is reported for the first time. This work represents a comprehensive study of the absorption spectra of DMF in the VUV and infrared regions.

Low frequency noise elimination technique for 24-bit Σ-Δ data acquisition systems.

PubMed

Qu, Shao-Bo; Robert, Olivier; Lognonné, Philippe; Zhou, Ze-Bing; Yang, Shan-Qing

2015-03-01

Low frequency 1/f noise is one of the key limiting factors of high precision measurement instruments. In this paper, digital correlated double sampling is implemented to reduce the offset and low frequency 1/f noise of a data acquisition system with 24-bit sigma delta (Σ-Δ) analog to digital converter (ADC). The input voltage is modulated by cross-coupled switches, which are synchronized to the sampling clock, and converted into digital signal by ADC. By using a proper switch frequency, the unwanted parasitic signal frequencies generated by the switches are avoided. The noise elimination processing is made through the principle of digital correlated double sampling, which is equivalent to a time shifted subtraction for the sampled voltage. The low frequency 1/f noise spectrum density of the data acquisition system is reduced to be flat down to the measurement frequency lower limit, which is about 0.0001 Hz in this paper. The noise spectrum density is eliminated by more than 60 dB at 0.0001 Hz, with a residual noise floor of (9 ± 2) nV/Hz(1/2) which is limited by the intrinsic white noise floor of the ADC above its corner frequency.

Longitudinal development of manual motor ability in autism spectrum disorder from childhood to mid-adulthood relates to adaptive daily living skills.

PubMed

Travers, Brittany G; Bigler, Erin D; Duffield, Tyler C; Prigge, Molly D B; Froehlich, Alyson L; Lange, Nicholas; Alexander, Andrew L; Lainhart, Janet E

2017-07-01

Many individuals with autism spectrum disorder (ASD) exhibit motor difficulties, but it is unknown whether manual motor skills improve, plateau, or decline in ASD in the transition from childhood into adulthood. Atypical development of manual motor skills could impact the ability to learn and perform daily activities across the life span. This study examined longitudinal grip strength and finger tapping development in individuals with ASD (n = 90) compared to individuals with typical development (n = 56), ages 5 to 40 years old. We further examined manual motor performance as a possible correlate of current and future daily living skills. The group with ASD demonstrated atypical motor development, characterized by similar performance during childhood but increasingly poorer performance from adolescence into adulthood. Grip strength was correlated with current adaptive daily living skills, and Time 1 grip strength predicted daily living skills eight years into the future. These results suggest that individuals with ASD may experience increasingly more pronounced motor difficulties from adolescence into adulthood and that manual motor performance in ASD is related to adaptive daily living skills. © 2016 John Wiley & Sons Ltd.

Validation of the Pictorial Infant Communication Scale for preschool-aged children with autism spectrum disorder.

PubMed

Ghilain, Christine S; Parlade, Meaghan V; McBee, Matthew T; Coman, Drew C; Owen, Taylor; Gutierrez, Anibal; Boyd, Brian; Odom, Samuel; Alessandri, Michael

2017-02-01

Joint attention, or the shared focus of attention between objects or events and a social partner, is a crucial milestone in the development of social communication and a notable area of deficit in children with autism spectrum disorder. While valid parent-report screening measures of social communication are available, the majority of these measures are designed to assess a wide range of behaviors. Targeted assessment of joint attention and related skills is primarily limited to semi-structured, examiner-led interactions, which are time-consuming and laborious to score. The Pictorial Infant Communication Scale is an efficient parent-report measure of joint attention that can be used as a complement to structured assessments in fully characterizing early social communication development. This study examined the psychometric properties of the Pictorial Infant Communication Scale. Results revealed a high degree of internal consistency and strong intercorrelations between subscales. Additionally, confirmatory factor analysis supported a three-factor model of joint attention. Furthermore, significant correlations between the Pictorial Infant Communication Scale and direct clinical measures of child joint attention, language skills, and autism spectrum disorder symptom severity were suggestive of concurrent validity. Findings suggest that the Pictorial Infant Communication Scale is a promising tool for measuring joint attention skills in preschool-aged children with autism spectrum disorder.

Psychotic-spectrum symptoms, cumulative adversity exposure and substance use among high-risk girls.

PubMed

Lansing, Amy E; Plante, Wendy Y; Fennema-Notestine, Christine; Golshan, Shahrokh; Beck, Audrey N

2018-02-01

Psychotic-spectrum symptoms are linked to trauma, substance/alcohol use (SAU), criminality/violence and poor functional outcomes, supporting the need for early detection in vulnerable populations. To better understand high-risk girls' mental health, we assessed: (1) psychotic-spectrum symptoms; (2) cumulative trauma, adversity and loss exposures (C-TALE) and adversity-indicators (symptoms, maladaptive coping, stressor-reactivity); and SAU risk-factors; and (3) relationships among psychotic-spectrum symptoms, adversity-indicators and SAU risk-factors. We administered the Structured Clinical Interviews for Psychotic Spectrum, and Trauma and Loss Spectrum to 158 adolescent delinquent girls. Girls' psychotic-spectrum profiles were similar to previously reported adult psychotic patients and characterized by typical symptoms (hallucinations/delusions, reported largely SAU-independent), interpersonal sensitivity, schizoid traits and paranoia (over-interpretation, anger over-reactivity, hypervigilance). Auditory/visual hallucinations (55.7%), delusions (92.4%), ideas of reference (96.8%) and adversity (90.0% ≥10/24 C-TALE-types) were common. Mean loss (4) and trauma (8) onset-age occurred before SAU-onset (12). Significant positive correlations were found among psychotic-spectrum symptoms, stressor-reactivity, C-TALE, adversity-indicators; and number of SAU-types; and a negative correlation occurred between psychotic-spectrum symptoms and earlier alcohol use onset. After controlling for number of SAU-types, stressor-reactivity and adversity-related numbing individually had the largest associations with total psychotic-spectrum symptoms (b = 2.6-4.3). Girls averaged more than 4 maladaptive coping strategies (e.g., 24.8% attempted suicide) in response to adversity, amplifying potential health-disparities. No racial/ethnic differences emerged on psychotic-spectrum symptoms. This symptom constellation during adolescence likely interferes with social and academic functioning. Whether representing a prodromal phase, trauma-response or cross-diagnostic psychopathology, accurate early detection and appropriate treatment of psychotic-spectrum symptoms are warranted to improve functional outcomes in vulnerable populations. © 2017 John Wiley & Sons Australia, Ltd.

Relativistic jet feedback - II. Relationship to gigahertz peak spectrum and compact steep spectrum radio galaxies

NASA Astrophysics Data System (ADS)

Bicknell, Geoffrey V.; Mukherjee, Dipanjan; Wagner, Alexander Y.; Sutherland, Ralph S.; Nesvadba, Nicole P. H.

2018-04-01

We propose that Gigahertz Peak Spectrum (GPS) and Compact Steep Spectrum (CSS) radio sources are the signposts of relativistic jet feedback in evolving galaxies. Our simulations of relativistic jets interacting with a warm, inhomogeneous medium, utilizing cloud densities and velocity dispersions in the range derived from optical observations, show that free-free absorption can account for the ˜ GHz peak frequencies and low-frequency power laws inferred from the radio observations. These new computational models replace a power-law model for the free-free optical depth a more fundamental model involving disrupted log-normal distributions of warm gas. One feature of our new models is that at early stages, the low-frequency spectrum is steep but progressively flattens as a result of a broader distribution of optical depths, suggesting that the steep low-frequency spectra discovered by Callingham et al. may possibly be attributed to young sources. We also investigate the inverse correlation between peak frequency and size and find that the initial location on this correlation is determined by the average density of the warm ISM. The simulated sources track this correlation initially but eventually fall below it, indicating the need for a more extended ISM than presently modelled. GPS and CSS sources can potentially provide new insights into the phenomenon of AGN feedback since their peak frequencies and spectra are indicative of the density, turbulent structure, and distribution of gas in the host galaxy.

Statistics of a neuron model driven by asymmetric colored noise.

PubMed

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.

Analysis of cross-correlations in electroencephalogram signals as an approach to proactive diagnosis of schizophrenia

NASA Astrophysics Data System (ADS)

Timashev, Serge F.; Panischev, Oleg Yu.; Polyakov, Yuriy S.; Demin, Sergey A.; Kaplan, Alexander Ya.

2012-02-01

We apply flicker-noise spectroscopy (FNS), a time series analysis method operating on structure functions and power spectrum estimates, to study the clinical electroencephalogram (EEG) signals recorded in children/adolescents (11 to 14 years of age) with diagnosed schizophrenia-spectrum symptoms at the National Center for Psychiatric Health (NCPH) of the Russian Academy of Medical Sciences. The EEG signals for these subjects were compared with the signals for a control sample of chronically depressed children/adolescents. The purpose of the study is to look for diagnostic signs of subjects' susceptibility to schizophrenia in the FNS parameters for specific electrodes and cross-correlations between the signals simultaneously measured at different points on the scalp. Our analysis of EEG signals from scalp-mounted electrodes at locations F3 and F4, which are symmetrically positioned in the left and right frontal areas of cerebral cortex, respectively, demonstrates an essential role of frequency-phase synchronization, a phenomenon representing specific correlations between the characteristic frequencies and phases of excitations in the brain. We introduce quantitative measures of frequency-phase synchronization and systematize the values of FNS parameters for the EEG data. The comparison of our results with the medical diagnoses for 84 subjects performed at NCPH makes it possible to group the EEG signals into 4 categories corresponding to different risk levels of subjects' susceptibility to schizophrenia. We suggest that the introduced quantitative characteristics and classification of cross-correlations may be used for the diagnosis of schizophrenia at the early stages of its development.

The importance of including local correlation times in the calculation of inter-proton distances from NMR measurements: ignoring local correlation times leads to significant errors in the conformational analysis of the Glc alpha1-2Glc alpha linkage by NMR spectroscopy.

PubMed

Mackeen, Mukram; Almond, Andrew; Cumpstey, Ian; Enis, Seth C; Kupce, Eriks; Butters, Terry D; Fairbanks, Antony J; Dwek, Raymond A; Wormald, Mark R

2006-06-07

The experimental determination of oligosaccharide conformations has traditionally used cross-linkage 1H-1H NOE/ROEs. As relatively few NOEs are observed, to provide sufficient conformational constraints this method relies on: accurate quantification of NOE intensities (positive constraints); analysis of absent NOEs (negative constraints); and hence calculation of inter-proton distances using the two-spin approximation. We have compared the results obtained by using 1H 2D NOESY, ROESY and T-ROESY experiments at 500 and 700 MHz to determine the conformation of the terminal Glc alpha1-2Glc alpha linkage in a dodecasaccharide and a related tetrasaccharide. For the tetrasaccharide, the NOESY and ROESY spectra produced the same qualitative pattern of linkage cross-peaks but the quantitative pattern, the relative peak intensities, was different. For the dodecasaccharide, the NOESY and ROESY spectra at 500 MHz produced a different qualitative pattern of linkage cross-peaks, with fewer peaks in the NOESY spectrum. At 700 MHz, the NOESY and ROESY spectra of the dodecasaccharide produced the same qualitative pattern of peaks, but again the relative peak intensities were different. These differences are due to very significant differences in the local correlation times for different proton pairs across this glycosidic linkage. The local correlation time for each proton pair was measured using the ratio of the NOESY and T-ROESY cross-relaxation rates, leaving the NOESY and ROESY as independent data sets for calculating the inter-proton distances. The inter-proton distances calculated including the effects of differences in local correlation times give much more consistent results.

Observations of blazars with ASCA

NASA Technical Reports Server (NTRS)

Makino, F.; Edelson, R.; Fujimoto, R.; Kii, T.; Idesawa, E.; Makishima, K.; Takahashi, T.; Sasaki, K.; Kamae, T.; Kubo, H.;

Reconstructing the primordial spectrum of fluctuations of the universe from the observed nonlinear clustering of galaxies

NASA Technical Reports Server (NTRS)

Hamilton, A. J. S.; Matthews, Alex; Kumar, P.; Lu, Edward

1991-01-01

It was discovered that the nonlinear evolution of the two point correlation function in N-body experiments of galaxy clustering with Omega = 1 appears to be described to good approximation by a simple general formula. The underlying form of the formula is physically motivated, but its detailed representation is obtained empirically by fitting to N-body experiments. In this paper, the formula is presented along with an inverse formula which converts a final, nonlinear correlation function into the initial linear correlation function. The inverse formula is applied to observational data from the CfA, IRAs, and APM galaxy surveys, and the initial spectrum of fluctuations of the universe, if Omega = 1.

Time-aware service-classified spectrum defragmentation algorithm for flex-grid optical networks

NASA Astrophysics Data System (ADS)

Qiu, Yang; Xu, Jing

2018-01-01

By employing sophisticated routing and spectrum assignment (RSA) algorithms together with a finer spectrum granularity (namely frequency slot) in resource allocation procedures, flex-grid optical networks can accommodate diverse kinds of services with high spectrum-allocation flexibility and resource-utilization efficiency. However, the continuity and the contiguity constraints in spectrum allocation procedures may always induce some isolated, small-sized, and unoccupied spectral blocks (known as spectrum fragments) in flex-grid optical networks. Although these spectrum fragments are left unoccupied, they can hardly be utilized by the subsequent service requests directly because of their spectral characteristics and the constraints in spectrum allocation. In this way, the existence of spectrum fragments may exhaust the available spectrum resources for a coming service request and thus worsens the networking performance. Therefore, many reactive defragmentation algorithms have been proposed to handle the fragmented spectrum resources via re-optimizing the routing paths and the spectrum resources for the existing services. But the routing-path and the spectrum-resource re-optimization in reactive defragmentation algorithms may possibly disrupt the traffic of the existing services and require extra components. By comparison, some proactive defragmentation algorithms (e.g. fragmentation-aware algorithms) were proposed to suppress spectrum fragments from their generation instead of handling the fragmented spectrum resources. Although these proactive defragmentation algorithms induced no traffic disruption and required no extra components, they always left the generated spectrum fragments unhandled, which greatly affected their efficiency in spectrum defragmentation. In this paper, by comprehensively considering the characteristics of both the reactive and the proactive defragmentation algorithms, we proposed a time-aware service-classified (TASC) spectrum defragmentation algorithm, which simultaneously employed proactive and reactive mechanisms in suppressing spectrum fragments with the awareness of services' types and their duration times. By dividing the spectrum resources into several flexible groups according to services' types and limiting both the spectrum allocation and the spectrum re-tuning for a certain service inside one specific spectrum group according to its type, the proposed TASC defragmentation algorithm cannot only suppress spectrum fragments from generation inside each spectrum group, but also handle the fragments generated between two adjacent groups. In this way, the proposed TASC algorithm gains higher efficiency in suppressing spectrum fragments than both the reactive and the proactive defragmentation algorithms. Additionally, as the generation of spectrum fragments is retrained between spectrum groups and the defragmentation procedure is limited inside each spectrum group, the induced traffic disruption for the existing services can be possibly reduced. Besides, the proposed TASC defragmentation algorithm always re-tunes the spectrum resources of the service with the maximum duration time first in spectrum defragmentation procedure, which can further reduce spectrum fragments because of the fact that the services with longer duration times always have higher possibility in inducing spectrum fragments than the services with shorter duration times. The simulation results show that the proposed TASC defragmentation algorithm can significantly reduce the number of the generated spectrum fragments while improving the service blocking performance.

Event-Based Processing of Neutron Scattering Data

DOE PAGES

Peterson, Peter F.; Campbell, Stuart I.; Reuter, Michael A.; ...

2015-09-16

Many of the world's time-of-flight spallation neutrons sources are migrating to the recording of individual neutron events. This provides for new opportunities in data processing, the least of which is to filter the events based on correlating them with logs of sample environment and other ancillary equipment. This paper will describe techniques for processing neutron scattering data acquired in event mode that preserve event information all the way to a final spectrum, including any necessary corrections or normalizations. This results in smaller final errors, while significantly reducing processing time and memory requirements in typical experiments. Results with traditional histogramming techniquesmore » will be shown for comparison.« less

Influence of sleep disorders on the behavior of individuals with autism spectrum disorder

PubMed Central

Fadini, Cintia C.; Lamônica, Dionísia A.; Fett-Conte, Agnes C.; Osório, Elaine; Zuculo, Gabriela M.; Giacheti, Célia M.; Pinato, Luciana

2015-01-01

The aim of this study was to investigate the correlation between sleep disorders and the behavior of subjects with autism spectrum disorder (ASD) and control subjects using specific questionnaires. A small percentage (1.8%) of the control subjects had symptoms indicative of sleep-breathing disorders (SBD) and nocturnal sweating. Fifty-nine percent of the subjects with ASD had symptoms indicative of at least one sleep disorder, with SBD the most commonly reported (38%). In the control group, the symptoms of SBD were correlated with social, thought, attentional, aggression, externalizing and behavioral problems. In the ASD group, disorders of arousal (DA) were correlated with thinking problems, and disorders of excessive somnolence were correlated with thinking and behavioral problems. These results suggest that children and adolescents with ASD have a high frequency of sleep disorders, which in turn correlate with some of the behavioral traits that they already exhibit. Furthermore, sleep disturbances, when present in the typically developing children, also correlated with behavioral problems. PMID:26150777

Clinical correlates of plasma brain-derived neurotrophic factor in post-traumatic stress disorder spectrum after a natural disaster.

PubMed

Stratta, Paolo; Sanità, Patrizia; Bonanni, Roberto L; de Cataldo, Stefano; Angelucci, Adriano; Rossi, Rodolfo; Origlia, Nicola; Domenici, Luciano; Carmassi, Claudia; Piccinni, Armando; Dell'Osso, Liliana; Rossi, Alessandro

2016-10-30

Clinical correlates of plasma Brain-Derived Neurotrophic Factor (BDNF) have been investigated in a clinical population with Post Traumatic Stress Disorder (PTSD) symptoms and healthy control subjects who survived to the L'Aquila 2009 earthquake. Twenty-six outpatients and 14 control subjects were recruited. Assessments included: Structured Clinical Interview for DSM-IV Axis-I disorders Patient Version, Trauma and Loss Spectrum-Self Report (TALS-SR) for post-traumatic spectrum symptoms. Thirteen patients were diagnosed as Full PTSD and 13 as Partial PTSD. The subjects with full-blown PTSD showed lower BDNF level than subjects with partial PTSD and controls. Different relationship patterns of BDNF with post-traumatic stress spectrum symptoms have been reported in the three samples. Our findings add more insight on the mechanisms regulating BDNF levels in response to stress and further proofs of the utility of the distinction of PTSD into full and partial categories. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Instantaneous frequency time analysis of physiology signals: The application of pregnant women’s radial artery pulse signals

NASA Astrophysics Data System (ADS)

Su, Zhi-Yuan; Wang, Chuan-Chen; Wu, Tzuyin; Wang, Yeng-Tseng; Tang, Feng-Cheng

2008-01-01

This study used the Hilbert-Huang transform, a recently developed, instantaneous frequency-time analysis, to analyze radial artery pulse signals taken from women in their 36th week of pregnancy and after pregnancy. The acquired instantaneous frequency-time spectrum (Hilbert spectrum) is further compared with the Morlet wavelet spectrum. Results indicate that the Hilbert spectrum is especially suitable for analyzing the time series of non-stationary radial artery pulse signals since, in the Hilbert-Huang transform, signals are decomposed into different mode functions in accordance with signal’s local time scale. Therefore, the Hilbert spectrum contains more detailed information than the Morlet wavelet spectrum. From the Hilbert spectrum, we can see that radial artery pulse signals taken from women in their 36th week of pregnancy and after pregnancy have different patterns. This approach could be applied to facilitate non-invasive diagnosis of fetus’ physiological signals in the future.

Seeking Augmented Information Content Concerning Diurnal Precipitation Achieved by Combining TRMM-PR and CloudSat-CPR Radar Data Sets

NASA Technical Reports Server (NTRS)

Smith, Eric A.; Kuo, Kwo-Sen; Carty, Hezekiah

2008-01-01

The CloudSat satellite's Cloud Profiling Radar (CPR) is a highly sensitive 94 GHz (W-band) nadir viewing radar system flown in retrograde sun synchronous orbit useful for determining the vertical structure of cloud hydrometeors down to sensitivity of approx. -30 dBZ reflectivity factor. Given this sensitivity, it is possible to unambiguously measure precipitation rates in clouds over a spectrum extending from approx. 0.08 - 3.0 mm hr (sup -1) down to altitudes of 0.5 km with approx.0.25 km vertical binning. This enables an effective means to measure a great deal of the drizzle and light rain spectrum. However, because of its near-polar sunsynchronous orbit, CloudSat cannot sample the diurnal cycle of precipitation, nor with its nadir-only CPR view can it obtain a high duty cycle in sampling precipitation at fixed local times over fixed positions. On the other hand, the TRMM satellite, which is flown in a non-sunsynchronous 35-degree inclined orbit carrying the 13.8 GHz KU-band Precipitation Radar (PR) scanning through nadir over an approx. 225 km swath, can sample both the diurnal cycle and with a much improved duty cycle relative to CloudSat. Moreover, the PR and CPR have the same 0.25 km vertical binning capability. The PR's greatest shortcoming is its approx. +17 dBZ sensitivity, which eliminates the possibility of measuring rain rates below -0.3-0.5 mm hr(sup -1), which can involve rainfall accumulations of up to 50% of the total over some regions. This begs the question of whether by combining CPR and PR data sets, whether it is possible to obtain an augmented measurement of the diurnal precipitation cycle. By collecting complimentary datasets during CloudSat and TRMM satellite orbit crossings within a delta t = 45-min proximity window, it is possible to demonstrate that whenever TRMM detects a precipitation signal, the correlations along the vertical axis between the reflectivities acquired from the CPR and PR are in inverse proportion to the magnitude of the delta t proximity window. By taking advantage of these underlying correlations, it is possible to develop a functional which can be used to broaden the reflectivity spectrum, concomitantly the rain rate spectrum, of the PR measurements based on the inherently broader reflectivity spectrum of the CPR at the lower reflectivity end of the spectrum, concomitantly at lighter rain rates. With the functional in place, it is then possible to produce synthetic CloudSat precipitation imagery over the PR track and thus over the diurnal time period. These augmented data are then used to study the spectral-vertical diurnal properties of precipitation over oceanic regions observed by TRMM.

First measurement of the cross-correlation of CMB lensing and galaxy lensing

DOE PAGES

Hand, Nick; Leauthaud, Alexie; Das, Sudeep; ...

2015-03-02

Here, we measure the cross-correlation of cosmic microwave background (CMB) lensing convergence maps derived from Atacama Cosmology Telescope data with galaxy lensing convergence maps as measured by the Canada-France-Hawaii Telescope Stripe 82 Survey. The CMB-galaxy lensing cross power spectrum is measured for the first time with a significance of 4.2 sigma, which corresponds to a 12% constraint on the amplitude of density fluctuations at redshifts ~0.9. With upcoming improved lensing data, this novel type of measurement will become a powerful cosmological probe, providing a precise measurement of the mass distribution at intermediate redshifts and serving as a calibrator for systematicmore » biases in weak lensing measurements.« less

Correlation of Noise Signature to Pulsed Power Events at the HERMES III Accelerator.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, Barbara; Joseph, Nathan Ryan; Salazar, Juan Diego

2016-11-01

The HERMES III accelerator, which is located at Sandia National Laboratories' Tech Area IV, is the largest pulsed gamma X-ray source in the world. The accelerator is made up of 20 inductive cavities that are charged to 1 MV each by complex pulsed power circuitry. The firing time of the machine components ranges between the microsecond and nanosecond timescales. This results in a variety of electromagnetic frequencies when the accelerator fires. Testing was done to identify the HERMES electromagnetic noise signal and to map it to the various accelerator trigger events. This report will show the measurement methods used tomore » capture the noise spectrum produced from the machine and correlate this noise signature with machine events.« less

[Analysis of UV-visible absorption spectrum on the decolorization of industrial wastewater by disinfection].

PubMed

Huang, Xin; Wang, Long-Yong; Gao, Nai-Yun; Li, Wei-Guo

2012-10-01

The UV-Visible absorption spectrum of industrial wastewater was explored to introduce a substituting method determining the color of water, and to compare the decolorization efficacy of different disinfectants. The results show that the visible absorption spectrum(350-600 nm), instead of ultraviolet absorption spectrum, should be applied to characterize the color of wastewater. There is a good correlation between the features of visible absorption spectrum and the true color of wastewater. Both ozone and chlorine dioxide has a better decolorization performance than chlorine. However, the color of chlorine dioxide itself has a negative effect on decolorization. The changes in the features of visible absorption spectrum effectively reflect the variations in the color of wastewater after disinfection.

Opportunistic Capacity-Based Resource Allocation for Chunk-Based Multi-Carrier Cognitive Radio Sensor Networks

PubMed Central

Huang, Jie; Zeng, Xiaoping; Jian, Xin; Tan, Xiaoheng; Zhang, Qi

2017-01-01

The spectrum allocation for cognitive radio sensor networks (CRSNs) has received considerable research attention under the assumption that the spectrum environment is static. However, in practice, the spectrum environment varies over time due to primary user/secondary user (PU/SU) activity and mobility, resulting in time-varied spectrum resources. This paper studies resource allocation for chunk-based multi-carrier CRSNs with time-varied spectrum resources. We present a novel opportunistic capacity model through a continuous time semi-Markov chain (CTSMC) to describe the time-varied spectrum resources of chunks and, based on this, a joint power and chunk allocation model by considering the opportunistically available capacity of chunks is proposed. To reduce the computational complexity, we split this model into two sub-problems and solve them via the Lagrangian dual method. Simulation results illustrate that the proposed opportunistic capacity-based resource allocation algorithm can achieve better performance compared with traditional algorithms when the spectrum environment is time-varied. PMID:28106803

Full-Counting Many-Particle Dynamics: Nonlocal and Chiral Propagation of Correlations

NASA Astrophysics Data System (ADS)

Ashida, Yuto; Ueda, Masahito

2018-05-01

The ability to measure single quanta allows the complete characterization of small quantum systems known as full-counting statistics. Quantum gas microscopy enables one to observe many-body systems at the single-atom precision. We extend the idea of full-counting statistics to nonequilibrium open many-particle dynamics and apply it to discuss the quench dynamics. By way of illustration, we consider an exactly solvable model to demonstrate the emergence of unique phenomena such as nonlocal and chiral propagation of correlations, leading to a concomitant oscillatory entanglement growth. We find that correlations can propagate beyond the conventional maximal speed, known as the Lieb-Robinson bound, at the cost of probabilistic nature of quantum measurement. These features become most prominent at the real-to-complex spectrum transition point of an underlying parity-time-symmetric effective non-Hermitian Hamiltonian. A possible experimental situation with quantum gas microscopy is discussed.

Barriers to Physical Activity in Children With Autism Spectrum Disorders: Relationship to Physical Activity and Screen Time.

PubMed

Must, Aviva; Phillips, Sarah; Curtin, Carol; Bandini, Linda G

2015-04-01

Individual, social, and community barriers to physical activity (PA) experienced by children with autism spectrum disorder (ASD) make PA participation more difficult and may contribute to increased screen time. We compared the prevalence of parent-reported barriers to PA among 58 typically developing (TD) children and 53 children with an ASD, 3 to 11 years, and assessed the association between barriers and PA participation and screen time among children with ASD. Parents of children with ASD reported significantly more barriers than parents of TD children. Based on parent-report, 60% of children with ASD required too much supervision compared with no TD children (P < .001). Parents of children with ASD were more likely to report that adults lack skills needed to include their child (58%), that their child has few friends (45%), and that other children exclude their child (23%). The number of parent-reported barriers to PA was inversely correlated with the hours spent in PA per year (r = -0.27, P = .05) and positively related to total screen time (r = .32, P < .03). These findings underscore the need for community-based PA programs designed to meet the special requirements of this population and policies that compel schools and other government-supported organizations for inclusion and/or targeted programming.

Spectral Evolution of Intensive Microwave Bursts at Centimeter-Millimeter Wavelengths

NASA Astrophysics Data System (ADS)

Melnikov, V. F.; Magun, A.

The dynamics of the frequency spectrum of intensive broad band microwave bursts with one spectral maximum and simple time profiles are investigated. The aim of the study is to correlate the temporal evolution of the microwave burst spectrum above and below the spectral peak frequency f_p, as well as to compare these features with theoretical expectations. The analysis was carried out by using the data from the patrol instruments of IAP, Bern University and NIRFI, Nizhnii Novgorod (10 fixed frequencies in the range 1-50 GHz). It has been found for the majority of these bursts that: a) during the rise phase of the burst flux there is an anticorrelation of the absolute values of the spectral indices above and below peak frequency whereas a good correlation during the decay phase was found; b) time delays between flux profiles at neighbouring frequencies change sign under the transition from low to high frequencies. As a rule the lower frequency emission is delayed at frequencies below f_p whereas at high frequencies (f>f_p) the higher frequency emission is delayed (see also Melnikov and Magun, 1998). Qualitatively these results fit well the calculated spectral evolution of the gyrosynchrotron if one takes into account the flattening of the electron energy spectrum in a flare loop (Melnikov and Magun, 1996) due to Coulomb collisions (Vilmer et al., 1982), and uses values for the background plasma density derived from hard X-ray data (Aschwanden et al., 1997). For some of the bursts, however, quantitative discrepancies with the predictions of the homogeneous model have been found. For these bursts the absolute value of the spectral index at low frequencies is remarkably smaller, and the time delay remarkably higher than expected. We have investigated several possibilities to obtain an agremeent between theory and observations. Special attention is paid to model calculations taking into account the dynamics of energetic electrons in flare loops with an inhomogeneous magnetic field and plasma density. In this context the capabilities of the models for the diagnostics of the physical conditions in flare loops using observations with high spatial

Reconstruction of a Broadband Spectrum of Alfvenic Fluctuations

NASA Technical Reports Server (NTRS)

Vinas, Adolfo F.; Fuentes, Pablo S. M.; Araneda, Jaime A.; Maneva, Yana G.

2014-01-01

Alfvenic fluctuations in the solar wind exhibit a high degree of velocities and magnetic field correlations consistent with Alfven waves propagating away and toward the Sun. Two remarkable properties of these fluctuations are the tendencies to have either positive or negative magnetic helicity (-1 less than or equal to sigma(sub m) less than or equal to +1) associated with either left- or right- topological handedness of the fluctuations and to have a constant magnetic field magnitude. This paper provides, for the first time, a theoretical framework for reconstructing both the magnetic and velocity field fluctuations with a divergence-free magnetic field, with any specified power spectral index and normalized magnetic- and cross-helicity spectrum field fluctuations for any plasma species. The spectrum is constructed in the Fourier domain by imposing two conditions-a divergence-free magnetic field and the preservation of the sense of magnetic helicity in both spaces-as well as using Parseval's theorem for the conservation of energy between configuration and Fourier spaces. Applications to the one-dimensional spatial Alfvenic propagation are presented. The theoretical construction is in agreement with typical time series and power spectra properties observed in the solar wind. The theoretical ideas presented in this spectral reconstruction provide a foundation for more realistic simulations of plasma waves, solar wind turbulence, and the propagation of energetic particles in such fluctuating fields.

Spin-echo based diagonal peak suppression in solid-state MAS NMR homonuclear chemical shift correlation spectra

NASA Astrophysics Data System (ADS)

Wang, Kaiyu; Zhang, Zhiyong; Ding, Xiaoyan; Tian, Fang; Huang, Yuqing; Chen, Zhong; Fu, Riqiang

2018-02-01

The feasibility of using the spin-echo based diagonal peak suppression method in solid-state MAS NMR homonuclear chemical shift correlation experiments is demonstrated. A complete phase cycling is designed in such a way that in the indirect dimension only the spin diffused signals are evolved, while all signals not involved in polarization transfer are refocused for cancellation. A data processing procedure is further introduced to reconstruct this acquired spectrum into a conventional two-dimensional homonuclear chemical shift correlation spectrum. A uniformly 13C, 15N labeled Fmoc-valine sample and the transmembrane domain of a human protein, LR11 (sorLA), in native Escherichia coli membranes have been used to illustrate the capability of the proposed method in comparison with standard 13C-13C chemical shift correlation experiments.

The stability and validity of automated vocal analysis in preverbal preschoolers with autism spectrum disorder.

PubMed

Woynaroski, Tiffany; Oller, D Kimbrough; Keceli-Kaysili, Bahar; Xu, Dongxin; Richards, Jeffrey A; Gilkerson, Jill; Gray, Sharmistha; Yoder, Paul

2017-03-01

Theory and research suggest that vocal development predicts "useful speech" in preschoolers with autism spectrum disorder (ASD), but conventional methods for measurement of vocal development are costly and time consuming. This longitudinal correlational study examines the reliability and validity of several automated indices of vocalization development relative to an index derived from human coded, conventional communication samples in a sample of preverbal preschoolers with ASD. Automated indices of vocal development were derived using software that is presently "in development" and/or only available for research purposes and using commercially available Language ENvironment Analysis (LENA) software. Indices of vocal development that could be derived using the software available for research purposes: (a) were highly stable with a single day-long audio recording, (b) predicted future spoken vocabulary to a degree that was nonsignificantly different from the index derived from conventional communication samples, and (c) continued to predict future spoken vocabulary even after controlling for concurrent vocabulary in our sample. The score derived from standard LENA software was similarly stable, but was not significantly correlated with future spoken vocabulary. Findings suggest that automated vocal analysis is a valid and reliable alternative to time intensive and expensive conventional communication samples for measurement of vocal development of preverbal preschoolers with ASD in research and clinical practice. Autism Res 2017, 10: 508-519. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Evidence for broken Galilean invariance at the quantum spin Hall edge

NASA Astrophysics Data System (ADS)

Geissler, Florian; Crépin, François; Trauzettel, Björn

2015-12-01

We study transport properties of the helical edge channels of a quantum spin Hall insulator, in the presence of electron-electron interactions and weak, local Rashba spin-orbit coupling. The combination of the two allows for inelastic backscattering that does not break time-reversal symmetry, resulting in interaction-dependent power-law corrections to the conductance. Here, we use a nonequilibrium Keldysh formalism to describe the situation of a long, one-dimensional edge channel coupled to external reservoirs, where the applied bias is the leading energy scale. By calculating explicitly the corrections to the conductance up to fourth order of the impurity strength, we analyze correlated single- and two-particle backscattering processes on a microscopic level. Interestingly, we show that the modeling of the leads together with the breaking of Galilean invariance has important effects on the transport properties. Such breaking occurs because the Galilean invariance of the bulk spectrum transforms into an emergent Lorentz invariance of the edge spectrum. With this broken Galilean invariance at the quantum spin Hall edge, we find a contribution to single-particle backscattering with a very low power scaling, while in the presence of Galilean invariance the leading contribution will be due to correlated two-particle backscattering only. This difference is further reflected in the different values of the Fano factor of the shot noise, an experimentally observable quantity. The described behavior is specific to the Rashba scatterer and does not occur in the case of backscattering off a time-reversal-breaking, magnetic impurity.

Hard to “tune in”: neural mechanisms of live face-to-face interaction with high-functioning autistic spectrum disorder

PubMed Central

Tanabe, Hiroki C.; Kosaka, Hirotaka; Saito, Daisuke N.; Koike, Takahiko; Hayashi, Masamichi J.; Izuma, Keise; Komeda, Hidetsugu; Ishitobi, Makoto; Omori, Masao; Munesue, Toshio; Okazawa, Hidehiko; Wada, Yuji; Sadato, Norihiro

2012-01-01

Persons with autism spectrum disorders (ASD) are known to have difficulty in eye contact (EC). This may make it difficult for their partners during face to face communication with them. To elucidate the neural substrates of live inter-subject interaction of ASD patients and normal subjects, we conducted hyper-scanning functional MRI with 21 subjects with autistic spectrum disorder (ASD) paired with typically-developed (normal) subjects, and with 19 pairs of normal subjects as a control. Baseline EC was maintained while subjects performed real-time joint-attention task. The task-related effects were modeled out, and inter-individual correlation analysis was performed on the residual time-course data. ASD–Normal pairs were less accurate at detecting gaze direction than Normal–Normal pairs. Performance was impaired both in ASD subjects and in their normal partners. The left occipital pole (OP) activation by gaze processing was reduced in ASD subjects, suggesting that deterioration of eye-cue detection in ASD is related to impairment of early visual processing of gaze. On the other hand, their normal partners showed greater activity in the bilateral occipital cortex and the right prefrontal area, indicating a compensatory workload. Inter-brain coherence in the right IFG that was observed in the Normal-Normal pairs (Saito et al., 2010) during EC diminished in ASD–Normal pairs. Intra-brain functional connectivity between the right IFG and right superior temporal sulcus (STS) in normal subjects paired with ASD subjects was reduced compared with in Normal–Normal pairs. This functional connectivity was positively correlated with performance of the normal partners on the eye-cue detection. Considering the integrative role of the right STS in gaze processing, inter-subject synchronization during EC may be a prerequisite for eye cue detection by the normal partner. PMID:23060772

[Preliminary study on effective components of Tripterygium wilfordii for liver toxicity based on spectrum-effect correlation analysis].

PubMed

Zhao, Xiao-Mei; Pu, Shi-Biao; Zhao, Qing-Guo; Gong, Man; Wang, Jia-Bo; Ma, Zhi-Jie; Xiao, Xiao-He; Zhao, Kui-Jun

2016-08-01

In this paper, the spectrum-effect correlation analysis method was used to explore the main effective components of Tripterygium wilfordii for liver toxicity, and provide reference for promoting the quality control of T. wilfordii. Chinese medicine T.wilfordii was taken as the study object, and LC-Q-TOF-MS was used to characterize the chemical components in T. wilfordii samples from different areas, and their main components were initially identified after referring to the literature. With the normal human hepatocytes (LO2 cell line)as the carrier, acetaminophen as positive medicine, and cell inhibition rate as testing index, the simple correlation analysis and multivariate linear correlation analysis methods were used to screen the main components of T. wilfordii for liver toxicity. As a result, 10 kinds of main components were identified, and the spectrum-effect correlation analysis showed that triptolide may be the toxic component, which was consistent with previous results of traditional literature. Meanwhile it was found that tripterine and demethylzeylasteral may greatly contribute to liver toxicity in multivariate linear correlation analysis. T. wilfordii samples of different varieties or different origins showed large difference in quality, and the T. wilfordii from southwest China showed lower liver toxicity, while those from Hunan and Anhui province showed higher liver toxicity. This study will provide data support for further rational use of T. wilfordii and research on its liver toxicity ingredients. Copyright© by the Chinese Pharmaceutical Association.

A decade of Rossi X-ray Timing Explorer Seyfert observations: An RXTE Seyfert spectral database

NASA Astrophysics Data System (ADS)

Mattson, Barbara Jo

2008-10-01

With over forty years of X-ray observations, we should have a grasp on the X- ray nature of active galactic nuclei (AGN). The unification model of Antonucci and Miller (1985) offered a context for understanding observations by defining a "typical" AGN geometry, with observed spectral differences explained by line- of-sight effects. However, the emerging picture is that the central AGN is more complex than unification alone can describe. We explore the unified model with a systematic X-ray spectral study of bright Seyfert galaxies observed by the Rossi X-Ray Timing Explorer (RXTE) over its first 10 years. We develop a spectral-fit database of 821 time-resolved spectra from 39 Seyfert galaxies fitted to a model describing the effects of an X-ray power-law spectrum reprocessed and absorbed by material in the central AGN region. We observe a relationship between radio and X-ray properties for Seyfert 1s, with the spectral parameters differing between radio-loud and radio-quiet Seyfert 1s. We also find a complex relationship between the Fe K equivalent width ( EW ) and the power-law photon index (Gamma) for the Seyfert 1s, with a correlation for the radio-loud sources and an anti-correlation for the radio- quiet sources. These results can be explained if X-rays from the relativistic jet in radio-loud sources contribute significantly to the observed spectrum. We observe scatter in the EW-Gamma relationship for the Seyfert 2s, suggesting complex environments that unification alone cannot explain. We see a strong correlation between Gamma and the reflection fraction ( R ) in the Seyfert 1 and 2 samples, but modeling degeneracies are present, so this relationship cannot be trusted as instructive of the AGN physics. For the Seyfert 1 sample, we find an anticorrelation between EW and the 2 to 10 keV luminosity ( L x ), also known as the X-ray Baldwin effect. This may suggest that higher luminosity sources contain less material or may be due to a time-lag effect. We do not observe the previously reported relationship between Gamma and the ratio of L x to the Eddington luminosity.

Examination of Correlates of Different Imitative Functions in Young Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Ingersoll, Brooke; Meyer, Katherine

2011-01-01

Children with autism spectrum disorders (ASD) have difficulties with social-communication skills, including imitation, language, joint attention, and play. This study investigated whether imitation performance in two different contexts (structured-elicited vs. social-interactive) was differentially related to attention-following, social…

Material identification employing a grating spectrometer

DOEpatents

Gornushkin, Ignor B.; Winefordner, James D.; Smith, Benjamin W.

2007-01-09

Multi-ordered spectral data is obtained from various known substances and is stored in a spectral library. The identification of an unknown material is accomplished by correlating the sample's multi-ordered spectrum against all or a portion of the spectrum in the library, and finding the closest match.

Solar spectrum matching with white OLED and monochromatic LEDs.

PubMed

Yu, Hui-Yuan; Cao, Guan-Ying; Zhang, Jing-Hui; Yang, Yi; Sun, Wen-Liang; Wang, Li-Ping; Zou, Nian-Yu

2018-04-01

In this paper, the solar spectrum matching in the visible range of 380-780 nm with white organic light-emitting diode (OLED) and monochromatic light-emitting diodes (LEDs) is investigated. The correlation index ( R 2 ) is used to evaluate the difference between the matching spectrum and the solar spectrum. The optimal combination is obtained by the least squares method. We also perform subtraction experiments to find the optimal combination. We utilize a common white OLED device design and just change the species of monochromatic LEDs used. We report and evaluate different degrees of matching effects. The results show that the correlation index of the best combination can reach 94.09% with white OLED and 36 monochromatic LEDs. We define three levels of performance as an evaluation system in accordance with the matching effect. The level is excellent with an R 2 above 90.14%. The good level is from 86.65% to 58.28%. From 42.08% to 33.06% is the reasonable level. Compared with other methods, using white OLED combined with monochromatic LEDs achieves the best solar spectrum matching effect. The results can be applied to different requirements of engineering practice.

Optical Variability Signatures from Massive Black Hole Binaries

NASA Astrophysics Data System (ADS)

Kasliwal, Vishal P.; Frank, Koby Alexander; Lidz, Adam

2017-01-01

The hierarchical merging of dark matter halos and their associated galaxies should lead to a population of supermassive black hole binaries (MBHBs). We consider plausible optical variability signatures from MBHBs at sub-parsec separations and search for these using data from the Catalina Real-Time Transient Survey (CRTS). Specifically, we model the impact of relativistic Doppler beaming on the accretion disk emission from the less massive, secondary black hole. We explore whether this Doppler modulation may be separated from other sources of stochastic variability in the accretion flow around the MBHBs, which we describe as a damped random walk (DRW). In the simple case of a circular orbit, relativistic beaming leads to a series of broad peaks — located at multiples of the orbital frequency — in the fluctuation power spectrum. We extend our analysis to the case of elliptical orbits and discuss the effect of beaming on the flux power spectrum and auto-correlation function using simulations. We present a code to model an observed light curve as a stochastic DRW-type time series modulated by relativistic beaming and apply the code to CRTS data.

Radial and poloidal correlation reflectometry on Experimental Advanced Superconducting Tokamak

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qu, Hao; Zhang, Tao; Han, Xiang

2015-08-15

An X-mode polarized V band (50 GHz–75 GHz) radial and poloidal correlation reflectometry is designed and installed on Experimental Advanced Superconducting Tokamak (EAST). Two frequency synthesizers (12 GHz–19 GHz) are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together for launching through one single pyramidal antenna. Two poloidally separated antennae are installed to receive the reflected waves from plasma. This reflectometry system can be used for radial and poloidal correlation measurement of the electron density fluctuation. In ohmically heated plasma, the radial correlation length is about 1.5 cm measured bymore » the system. The poloidal correlation analysis provides a means to estimate the fluctuation velocity perpendicular to the main magnetic field. In the present paper, the distance between two poloidal probing points is calculated with ray-tracing code and the propagation time is deduced from cross-phase spectrum. Fluctuation velocity perpendicular to the main magnetic field in the core of ohmically heated plasma is about from −1 km/s to −3 km/s.« less

Interuser Interference Analysis for Direct-Sequence Spread-Spectrum Systems Part I: Partial-Period Cross-Correlation

NASA Technical Reports Server (NTRS)

Ni, Jianjun (David)

2012-01-01

This presentation discusses an analysis approach to evaluate the interuser interference for Direct-Sequence Spread-Spectrum (DSSS) Systems for Space Network (SN) Users. Part I of this analysis shows that the correlation property of pseudo noise (PN) sequences is the critical factor which determines the interuser interference performance of the DSSS system. For non-standard DSSS systems in which PN sequence s period is much larger than one data symbol duration, it is the partial-period cross-correlation that determines the system performance. This study reveals through an example that a well-designed PN sequence set (e.g. Gold Sequence, in which the cross-correlation for a whole-period is well controlled) may have non-controlled partial-period cross-correlation which could cause severe interuser interference for a DSSS system. Since the analytical derivation of performance metric (bit error rate or signal-to-noise ratio) based on partial-period cross-correlation is prohibitive, the performance degradation due to partial-period cross-correlation will be evaluated using simulation in Part II of this analysis in the future.

[Application of wavelet transform and neural network in the near-infrared spectrum analysis of oil shale].

PubMed

Li, Su-Yi; Ji, Yan-Ju; Liu, Wei-Yu; Wang, Zhi-Hong

2013-04-01

In the present study, an innovative method is proposed, employing both wavelet transform and neural network, to analyze the near-infrared spectrum data in oil shale survey. The method entails using db8 wavelet at 3 levels decomposition to process raw data, using the transformed data as the input matrix, and creating the model through neural network. To verify the validity of the method, this study analyzes 30 synthesized oil shale samples, in which 20 samples are randomly selected for network training, the other 10 for model prediction, and uses the full spectrum and the wavelet transformed spectrum to carry out 10 network models, respectively. Results show that the mean speed of the full spectrum neural network modeling is 570.33 seconds, and the predicted residual sum of squares (PRESS) and correlation coefficient of prediction are 0.006 012 and 0.843 75, respectively. In contrast, the mean speed of the wavelet network modeling method is 3.15 seconds, and the mean PRESS and correlation coefficient of prediction are 0.002 048 and 0.953 19, respectively. These results demonstrate that the wavelet neural network modeling method is significantly superior to the full spectrum neural network modeling method. This study not only provides a new method for more efficient and accurate detection of the oil content of oil shale, but also indicates the potential for applying wavelet transform and neutral network in broad near-infrared spectrum analysis.

Intrinsic reaction-cycle time scale of Na+,K+-ATPase manifests itself in the lipid–protein interactions of nonequilibrium membranes

PubMed Central

Bouvrais, Hélène; Cornelius, Flemming; Ipsen, John H.; Mouritsen, Ole G.

2012-01-01

Interaction between integral membrane proteins and the lipid-bilayer component of biological membranes is expected to mutually influence the proteins and the membrane. We present quantitative evidence of a manifestation of the lipid–protein interactions in liposomal membranes, reconstituted with actively pumping Na+,K+-ATPase, in terms of nonequilibrium shape fluctuations that contain a relaxation time, τ, which is robust and independent of the specific fluctuation modes of the membrane. In the case of pumping Na+-ions, analysis of the flicker-noise temporal correlation spectrum of the liposomes leads to τ ≃ 0.5 s, comparing favorably with an intrinsic reaction-cycle time of about 0.4 s from enzymology. PMID:23093677

Spectral and cross-spectral analysis of uneven time series with the smoothed Lomb-Scargle periodogram and Monte Carlo evaluation of statistical significance

NASA Astrophysics Data System (ADS)

Pardo-Igúzquiza, Eulogio; Rodríguez-Tovar, Francisco J.

2012-12-01

Many spectral analysis techniques have been designed assuming sequences taken with a constant sampling interval. However, there are empirical time series in the geosciences (sediment cores, fossil abundance data, isotope analysis, …) that do not follow regular sampling because of missing data, gapped data, random sampling or incomplete sequences, among other reasons. In general, interpolating an uneven series in order to obtain a succession with a constant sampling interval alters the spectral content of the series. In such cases it is preferable to follow an approach that works with the uneven data directly, avoiding the need for an explicit interpolation step. The Lomb-Scargle periodogram is a popular choice in such circumstances, as there are programs available in the public domain for its computation. One new computer program for spectral analysis improves the standard Lomb-Scargle periodogram approach in two ways: (1) It explicitly adjusts the statistical significance to any bias introduced by variance reduction smoothing, and (2) it uses a permutation test to evaluate confidence levels, which is better suited than parametric methods when neighbouring frequencies are highly correlated. Another novel program for cross-spectral analysis offers the advantage of estimating the Lomb-Scargle cross-periodogram of two uneven time series defined on the same interval, and it evaluates the confidence levels of the estimated cross-spectra by a non-parametric computer intensive permutation test. Thus, the cross-spectrum, the squared coherence spectrum, the phase spectrum, and the Monte Carlo statistical significance of the cross-spectrum and the squared-coherence spectrum can be obtained. Both of the programs are written in ANSI Fortran 77, in view of its simplicity and compatibility. The program code is of public domain, provided on the website of the journal (http://www.iamg.org/index.php/publisher/articleview/frmArticleID/112/). Different examples (with simulated and real data) are described in this paper to corroborate the methodology and the implementation of these two new programs.

A perturbative approach to the redshift space correlation function: beyond the Standard Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, Benjamin; Koyama, Kazuya, E-mail: benjamin.bose@port.ac.uk, E-mail: kazuya.koyama@port.ac.uk

We extend our previous redshift space power spectrum code to the redshift space correlation function. Here we focus on the Gaussian Streaming Model (GSM). Again, the code accommodates a wide range of modified gravity and dark energy models. For the non-linear real space correlation function used in the GSM we use the Fourier transform of the RegPT 1-loop matter power spectrum. We compare predictions of the GSM for a Vainshtein screened and Chameleon screened model as well as GR. These predictions are compared to the Fourier transform of the Taruya, Nishimichi and Saito (TNS) redshift space power spectrum model whichmore » is fit to N-body data. We find very good agreement between the Fourier transform of the TNS model and the GSM predictions, with ≤ 6% deviations in the first two correlation function multipoles for all models for redshift space separations in 50Mpc h ≤ s ≤ 180Mpc/ h . Excellent agreement is found in the differences between the modified gravity and GR multipole predictions for both approaches to the redshift space correlation function, highlighting their matched ability in picking up deviations from GR. We elucidate the timeliness of such non-standard templates at the dawn of stage-IV surveys and discuss necessary preparations and extensions needed for upcoming high quality data.« less

Diagnoses of Autism Spectrum Disorders in Germany: Time Trends in Administrative Prevalence and Diagnostic Stability

ERIC Educational Resources Information Center

Bachmann, Christian J.; Gerste, Bettina; Hoffmann, Falk

2018-01-01

For Germany, no data on trends in autism spectrum disorder diagnoses are available. The primary aim of this study was to establish the time trends in the administrative prevalence of autism spectrum disorder diagnoses. The second aim was to assess the stability of autism spectrum disorder diagnoses over time. We analysed administrative outpatient…

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seljak, Uroš; McDonald, Patrick, E-mail: useljak@berkeley.edu, E-mail: pvmcdonald@lbl.gov

We develop a phase space distribution function approach to redshift space distortions (RSD), in which the redshift space density can be written as a sum over velocity moments of the distribution function. These moments are density weighted and have well defined physical interpretation: their lowest orders are density, momentum density, and stress energy density. The series expansion is convergent if kμu/aH < 1, where k is the wavevector, H the Hubble parameter, u the typical gravitational velocity and μ = cos θ, with θ being the angle between the Fourier mode and the line of sight. We perform an expansionmore » of these velocity moments into helicity modes, which are eigenmodes under rotation around the axis of Fourier mode direction, generalizing the scalar, vector, tensor decomposition of perturbations to an arbitrary order. We show that only equal helicity moments correlate and derive the angular dependence of the individual contributions to the redshift space power spectrum. We show that the dominant term of μ{sup 2} dependence on large scales is the cross-correlation between the density and scalar part of momentum density, which can be related to the time derivative of the matter power spectrum. Additional terms contributing to μ{sup 2} and dominating on small scales are the vector part of momentum density-momentum density correlations, the energy density-density correlations, and the scalar part of anisotropic stress density-density correlations. The second term is what is usually associated with the small scale Fingers-of-God damping and always suppresses power, but the first term comes with the opposite sign and always adds power. Similarly, we identify 7 terms contributing to μ{sup 4} dependence. Some of the advantages of the distribution function approach are that the series expansion converges on large scales and remains valid in multi-stream situations. We finish with a brief discussion of implications for RSD in galaxies relative to dark matter, highlighting the issue of scale dependent bias of velocity moments correlators.« less

Terrestrial gamma-ray flashes

NASA Astrophysics Data System (ADS)

Marisaldi, Martino; Fuschino, Fabio; Labanti, Claudio; Tavani, Marco; Argan, Andrea; Del Monte, Ettore; Longo, Francesco; Barbiellini, Guido; Giuliani, Andrea; Trois, Alessio; Bulgarelli, Andrea; Gianotti, Fulvio; Trifoglio, Massimo

2013-08-01

Lightning and thunderstorm systems in general have been recently recognized as powerful particle accelerators, capable of producing electrons, positrons, gamma-rays and neutrons with energies as high as several tens of MeV. In fact, these natural systems turn out to be the highest energy and most efficient natural particle accelerators on Earth. Terrestrial Gamma-ray Flashes (TGFs) are millisecond long, very intense bursts of gamma-rays and are one of the most intriguing manifestation of these natural accelerators. Only three currently operative missions are capable of detecting TGFs from space: the RHESSI, Fermi and AGILE satellites. In this paper we review the characteristics of TGFs, including energy spectrum, timing structure, beam geometry and correlation with lightning, and the basic principles of the associated production models. Then we focus on the recent AGILE discoveries concerning the high energy extension of the TGF spectrum up to 100 MeV, which is difficult to reconcile with current theoretical models.

Size dependent magnetic and magneto-optical properties of Ni0.2Zn0.8Fe2O4 nanoparticles

NASA Astrophysics Data System (ADS)

Li, Oksana A.; Lin, Chun-Rong; Chen, Hung-Yi; Hsu, Hua-Shu; Shih, Kun-Yauh; Edelman, Irina S.; Wu, Kai-Wun; Tseng, Yaw-Teng; Ovchinnikov, Sergey G.; Lee, Jiann-Shing

2016-06-01

Ni0.2Zn0.8Fe2O4 spinel nanoparticles have been synthesized by combustion method. Average particles size varies from 15.5 to 50.0 nm depending on annealing temperature. Correlations between particles size and magnetic and magneto-optical properties are investigated. Magnetization dependences on temperature and external magnetic field correspond to the sum of paramagnetic and superparamagnetic response. Critical size of single-domain transition is found to be 15.9 nm. Magnetic circular dichroism (MCD) studies of nickel zinc spinel are presented here for the first time. The features in magnetic circular dichroism spectrum are assigned to the one-ion d-d transitions in Fe3+ and Ni2+ ions, as well to the intersublattice and intervalence charge transfer transitions. The MCD spectrum rearrangement was revealed with the change of the nanoparticles size.

Interstellar scintillation observations for PSR B0355+54

NASA Astrophysics Data System (ADS)

Xu, Y. H.; Lee, K. J.; Hao, L. F.; Wang, H. G.; Liu, Z. Y.; Yue, Y. L.; Yuan, J. P.; Li, Z. X.; Wang, M.; Dong, J.; Tan, J. J.; Chen, W.; Bai, J. M.

2018-06-01

In this paper, we report our investigation of pulsar scintillation phenomena by monitoring PSR B0355+54 at 2.25 GHz for three successive months using the Kunming 40-m radio telescope. We measured the dynamic spectrum, the two-dimensional correlation function and the secondary spectrum. These observations have a high signal-to-noise ratio (S/N ≥ 100). We detected scintillation arcs, which are rarely observable using such a small telescope. The sub-microsecond scale width of the scintillation arc indicates that the transverse scale of the structures on the scattering screen is as compact as astronomical unit size. Our monitoring shows that the scintillation bandwidth, the time-scale and the arc curvature of PSR B0355+54 were varying temporally. A plausible explanation would need to invoke a multiple-scattering-screen or multiple-scattering-structure scenario, in which different screens or ray paths dominate the scintillation process at different epochs.

Applications of surface acoustic and shallow bulk acoustic wave devices

NASA Astrophysics Data System (ADS)

Campbell, Colin K.

1989-10-01

Surface acoustic wave (SAW) device coverage includes delay lines and filters operating at selected frequencies in the range from about 10 MHz to 11 GHz; modeling with single-crystal piezoelectrics and layered structures; resonators and low-loss filters; comb filters and multiplexers; antenna duplexers; harmonic devices; chirp filters for pulse compression; coding with fixed and programmable transversal filters; Barker and quadraphase coding; adaptive filters; acoustic and acoustoelectric convolvers and correlators for radar, spread spectrum, and packet radio; acoustooptic processors for Bragg modulation and spectrum analysis; real-time Fourier-transform and cepstrum processors for radar and sonar; compressive receivers; Nyquist filters for microwave digital radio; clock-recovery filters for fiber communications; fixed-, tunable-, and multimode oscillators and frequency synthesizers; acoustic charge transport; and other SAW devices for signal processing on gallium arsenide. Shallow bulk acoustic wave device applications include gigahertz delay lines, surface-transverse-wave resonators employing energy-trapping gratings, and oscillators with enhanced performance and capability.

Isoscalar π π Scattering and the σ Meson Resonance from QCD

DOE PAGES

Briceño, Raul A.; Dudek, Jozef J.; Edwards, Robert G.; ...

2017-01-09

Here, we present for the first time a determination of the energy dependence of the isoscalar ππ elastic scattering phase-shift within a first-principles numerical lattice approach to QCD. We also compute the hadronic correlation functions including all required quark propagation diagrams. From these the discrete spectrum of states in the finite volume defined by the lattice boundary is extracted. From the volume dependence of the spectrum we obtain the S-wave phase-shift up to the Kmore » $$\\bar{K}$$ threshold. Calculations are performed at two values of the u, d quark mass corresponding to m π = 236, 391 MeV and the resulting amplitudes are described in terms of a σ meson which evolves from a bound-state below ππ threshold at the heavier quark mass, to a broad resonance at the lighter quark mass.« less

Parent-Reported Repetitive Behavior in Toddlers on the Autism Spectrum

ERIC Educational Resources Information Center

Schertz, Hannah H.; Odom, Samuel L.; Baggett, Baggett M.; Sideris, John H.

2016-01-01

Toddlers with autism spectrum disorder (ASD) were assessed on the Repetitive Behavior Scale-Revised (RBS-R), which we found to have acceptable internal consistency. Stereotypical subscale scores showed a negligible association with cognitive level, but correlated more strongly with adaptive and social indicators. Relative to earlier reported RBS-R…

Factor Analysis of the Autism Spectrum Screening Questionnaire

ERIC Educational Resources Information Center

Posserud, Britt; Lundervold, Astri J.; Steijnen, Maaike C.; Verhoeven, Sophie; Stormark, Kjell Morten; Gillberg, Christopher

2008-01-01

The present study investigated the factor structure of parent and teacher Autism Spectrum Screening Questionnaire (ASSQ) in a population of 7-9 years old children. For validation purposes, factors derived were correlated with results on the Strengths and Difficulties Questionnaire (SDQ). A three-factor solution was identified on both parent and…

Thriving in Youth with Autism Spectrum Disorder and Intellectual Disability

ERIC Educational Resources Information Center

Weiss, Jonathan A.; Burnham Riosa, Priscilla

2015-01-01

Most research on mental health in individuals with autism spectrum disorder (ASD) and intellectual disability (ID) has focused on deficits. We examined individual (i.e., sociocommunicative skills, adaptive behavior, functional cognitive skills) and contextual (i.e., home, school, and community participation) correlates of thriving in 330 youth…

Neuroepileptic Correlates of Autistic Symptomatology in Tuberous Sclerosis

ERIC Educational Resources Information Center

Bolton, Patrick F.

2004-01-01

Tuberous sclerosis is a genetic condition that is strongly associated with the development of an autism spectrum disorder. However, there is marked variability in expression, and only a subset of children with tuberous sclerosis develop autism spectrum disorder. Clarification of the mechanisms that underlie the association and variability in…

Neural Correlates of Verbal and Nonverbal Semantic Integration in Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

McCleery, Joseph P.; Ceponiene, Rita; Burner, Karen M.; Townsend, Jeanne; Kinnear, Mikaela; Schreibman, Laura

2010-01-01

Background: Autism is a pervasive developmental disorder characterized by deficits in social-emotional, social-communicative, and language skills. Behavioral and neuroimaging studies have found that children with autism spectrum disorders (ASD) evidence abnormalities in semantic processing, with particular difficulties in verbal comprehension.…

The cerebrospinal fluid proteome in HIV infection: change associated with disease severity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Angel, Thomas E.; Jacobs, Jon M.; Spudich, Serena S.

2012-03-20

Central nervous system (CNS) infection is a constant feature of systemic HIV infection with a clinical spectrum that ranges from chronic asymptomatic infection to severe cognitive and motor dysfunction. Analysis of cerebrospinal fluid (CSF) has played an important part in defining the character of this evolving infection and response to treatment. To further characterize CNS HIV infection and its effects, we applied advanced high-throughput proteomic methods to CSF to identify novel proteins and their changes with disease progression and treatment. After establishing an accurate mass and time (AMT) tag database containing 23,141 AMT tags for CSF peptides, we analyzed 91more » CSF samples by LC-MS from 12 HIV-uninfected and 14 HIV-infected subjects studied in the context of initiation of antiretroviral and correlated abundances of identified proteins (a) within and between subjects, (b) with all other proteins across the entire sample set, and (c) with 'external' CSF biomarkers of infection (HIV RNA), immune activation (neopterin) and neural injury (neurofilament light chain protein, NFL). We identified a mean of 2,333 +/- 328 (SD) peptides covering 307 +/-16 proteins in the 91 CSF sample set. Protein abundances differed both between and within subjects sampled at different time points and readily separated those with and without HIV infection. Proteins also showed inter-correlations across the sample set that were associated with biologically relevant dynamic processes. One-hundred and fifty proteins showed correlations with the external biomarkers. For example, using a threshold of cross correlation coefficient (Pearson's) {le}0.3 and {ge}0.3 for potentially meaningful relationships, a total of 99 proteins correlated with CSF neopterin (43 negative and 56 positive correlations) and related principally to neuronal plasticity and survival and to innate immunity. Pathway analysis defined several networks connecting the identified proteins, including one with amyloid precursor protein as a central node. Advanced CSF proteomic analysis enabled the identification of an array of novel protein changes across the spectrum of CNS HIV infection and disease. This initial analysis clearly demonstrated the value of contemporary state-of-the-art proteomic CSF analysis as a discovery tool in HIV infection with likely similar application to other neurological inflammatory and degenerative diseases.« less

The cerebrospinal fluid proteome in HIV infection: change associated with disease severity

PubMed Central

2012-01-01

Background Central nervous system (CNS) infection is a nearly universal feature of untreated systemic HIV infection with a clinical spectrum that ranges from chronic asymptomatic infection to severe cognitive and motor dysfunction. Analysis of cerebrospinal fluid (CSF) has played an important part in defining the character of this evolving infection and response to treatment. To further characterize CNS HIV infection and its effects, we applied advanced high-throughput proteomic methods to CSF to identify novel proteins and their changes with disease progression and treatment. Results After establishing an accurate mass and time (AMT) tag database containing 23,141 AMT tags for CSF peptides, we analyzed 91 CSF samples by LC-MS from 12 HIV-uninfected and 14 HIV-infected subjects studied in the context of initiation of antiretroviral therapy and correlated abundances of identified proteins a) within and between subjects, b) with all other proteins across the entire sample set, and c) with "external" CSF biomarkers of infection (HIV RNA), immune activation (neopterin) and neural injury (neurofilament light chain protein, NFL). We identified a mean of 2,333 +/- 328 (SD) peptides covering 307 +/-16 proteins in the 91 CSF sample set. Protein abundances differed both between and within subjects sampled at different time points and readily separated those with and without HIV infection. Proteins also showed inter-correlations across the sample set that were associated with biologically relevant dynamic processes. One-hundred and fifty proteins showed correlations with the external biomarkers. For example, using a threshold of cross correlation coefficient (Pearson's) ≤ -0.3 and ≥0.3 for potentially meaningful relationships, a total of 99 proteins correlated with CSF neopterin (43 negative and 56 positive correlations) and related principally to neuronal plasticity and survival and to innate immunity. Pathway analysis defined several networks connecting the identified proteins, including one with amyloid precursor protein as a central node. Conclusions Advanced CSF proteomic analysis enabled the identification of an array of novel protein changes across the spectrum of CNS HIV infection and disease. This initial analysis clearly demonstrated the value of contemporary state-of-the-art proteomic CSF analysis as a discovery tool in HIV infection with likely similar application to other neurological inflammatory and degenerative diseases. PMID:22433316

Risk and correlates of autism spectrum disorder in children with epilepsy: a community-based study.

PubMed

Berg, Anne T; Plioplys, Sigita; Tuchman, Roberto

2011-05-01

The prevalence of autism spectrum disorders for children with epilepsy in the general population is unknown. In a prospective community-based study of newly diagnosed childhood epilepsy, autism spectrum disorder was determined from parental interviews, medical records, and expert reviews by a child psychiatrist. A total of 28 (5%) participants had autism spectrum disorders. West syndrome (prevalence ratio = 4.53, P = .002) and intellectual impairment (prevalence ratio = 4.34, P = .002) were independently associated with autism spectrum disorder. Absent West syndrome, male gender was associated with autism spectrum disorder (prevalence ratio = 3.71, P = .02). For participants with overall normal cognitive abilities, 2.2% had autism spectrum disorder, which is substantially higher than estimates from the general population (0.5%-0.9%). In addition to West syndrome, which has repeatedly been shown to have a special relationship with autism spectrum disorder, the most important determinants of autism spectrum disorder in the general population (intellectual impairment and male sex) are also important in young people with epilepsy.

Two Interrogated FBG Spectral Linewidth for Strain Sensing through Correlation.

PubMed

Hsu, Shih-Hsiang; Chuang, Kuo-Wei; Chen, Ci-Syu; Lin, Ching-Yu; Chang, Che-Chang

2017-12-07

The spectral linewidth from two cross-correlated fiber Bragg gratings (FBGs) are interrogated and characterized using a delayed self-homodyne method for fiber strain sensing. This approach employs a common higher frequency resolution instead of wavelength. A sensitivity and resolution of 166 MHz/με and 50 nε were demonstrated from 4 GHz spectral linewidth characterization on the electric spectrum analyzer. A 10 nε higher resolution can be expected through random noise analyses when the spectral linewidth from two FBG correlations is reduced to 1 GHz. Moreover, the FBG spectrum is broadened during strain and experimentally shows a 0.44 pm/με sensitivity, which is mainly caused by the photo elastic effect from the fiber grating period stretch.

Palus Somni - Anomalies in the correlation of Al/Si X-ray fluorescence intensity ratios and broad-spectrum visible albedos. [lunar surface mineralogy

NASA Technical Reports Server (NTRS)

Clark, P. E.; Andre, C. G.; Adler, I.; Weidner, J.; Podwysocki, M.

1976-01-01

The positive correlation between Al/Si X-ray fluorescence intensity ratios determined during the Apollo 15 lunar mission and a broad-spectrum visible albedo of the moon is quantitatively established. Linear regression analysis performed on 246 1 degree geographic cells of X-ray fluorescence intensity and visible albedo data points produced a statistically significant correlation coefficient of .78. Three distinct distributions of data were identified as (1) within one standard deviation of the regression line, (2) greater than one standard deviation below the line, and (3) greater than one standard deviation above the line. The latter two distributions of data were found to occupy distinct geographic areas in the Palus Somni region.

Faraday rotation from magnesium II absorbers toward polarized background radio sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farnes, J. S.; O'Sullivan, S. P.; Corrigan, M. E.

2014-11-01

Strong singly ionized magnesium (Mg II) absorption lines in quasar spectra typically serve as a proxy for intervening galaxies along the line of sight. Previous studies have found a correlation between the number of these Mg II absorbers and the Faraday rotation measure (RM) at ≈5 GHz. We cross-match a sample of 35,752 optically identified non-intrinsic Mg II absorption systems with 25,649 polarized background radio sources for which we have measurements of both the spectral index and RM at 1.4 GHz. We use the spectral index to split the resulting sample of 599 sources into flat-spectrum and steep-spectrum subsamples. Wemore » find that our flat-spectrum sample shows significant (∼3.5σ) evidence for a correlation between Mg II absorption and RM at 1.4 GHz, while our steep-spectrum sample shows no such correlation. We argue that such an effect cannot be explained by either luminosity or other observational effects, by evolution in another confounding variable, by wavelength-dependent polarization structure in an active galactic nucleus, by the Galactic foreground, by cosmological expansion, or by partial coverage models. We conclude that our data are most consistent with intervenors directly contributing to the Faraday rotation along the line of sight, and that the intervening systems must therefore have coherent magnetic fields of substantial strength ( B-bar =1.8±0.4 μG). Nevertheless, the weak nature of the correlation will require future high-resolution and broadband radio observations in order to place it on a much firmer statistical footing.« less

Spectrum of classes of point emitters of electromagnetic wave fields.

PubMed

Castañeda, Román

2016-09-01

The spectrum of classes of point emitters has been introduced as a numerical tool suitable for the design, analysis, and synthesis of non-paraxial optical fields in arbitrary states of spatial coherence. In this paper, the polarization state of planar electromagnetic wave fields is included in the spectrum of classes, thus increasing its modeling capabilities. In this context, optical processing is realized as a filtering on the spectrum of classes of point emitters, performed by the complex degree of spatial coherence and the two-point correlation of polarization, which could be implemented dynamically by using programmable optical devices.

Laser-induced differential normalized fluorescence method for cancer diagnosis

DOEpatents

Vo-Dinh, Tuan; Panjehpour, Masoud; Overholt, Bergein F.

1996-01-01

An apparatus and method for cancer diagnosis are disclosed. The diagnostic method includes the steps of irradiating a tissue sample with monochromatic excitation light, producing a laser-induced fluorescence spectrum from emission radiation generated by interaction of the excitation light with the tissue sample, and dividing the intensity at each wavelength of the laser-induced fluorescence spectrum by the integrated area under the laser-induced fluorescence spectrum to produce a normalized spectrum. A mathematical difference between the normalized spectrum and an average value of a reference set of normalized spectra which correspond to normal tissues is calculated, which provides for amplifying small changes in weak signals from malignant tissues for improved analysis. The calculated differential normalized spectrum is correlated to a specific condition of a tissue sample.

Laser-induced differential normalized fluorescence method for cancer diagnosis

DOEpatents

Vo-Dinh, T.; Panjehpour, M.; Overholt, B.F.

1996-12-03

An apparatus and method for cancer diagnosis are disclosed. The diagnostic method includes the steps of irradiating a tissue sample with monochromatic excitation light, producing a laser-induced fluorescence spectrum from emission radiation generated by interaction of the excitation light with the tissue sample, and dividing the intensity at each wavelength of the laser-induced fluorescence spectrum by the integrated area under the laser-induced fluorescence spectrum to produce a normalized spectrum. A mathematical difference between the normalized spectrum and an average value of a reference set of normalized spectra which correspond to normal tissues is calculated, which provides for amplifying small changes in weak signals from malignant tissues for improved analysis. The calculated differential normalized spectrum is correlated to a specific condition of a tissue sample. 5 figs.

CHARACTERIZING INTERMITTENCY OF 4-Hz QUASI-PERIODIC OSCILLATION IN XTE J1550–564 USING HILBERT–HUANG TRANSFORM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Su, Yi-Hao; Chou, Yi; Hu, Chin-Ping

We present time-frequency analysis results based on the Hilbert–Huang transform (HHT) for the evolution of a 4-Hz low-frequency quasi-periodic oscillation (LFQPO) around the black hole X-ray binary XTE J1550–564. The origin of LFQPOs is still debated. To understand the cause of the peak broadening, we utilized a recently developed time-frequency analysis, HHT, for tracking the evolution of the 4-Hz LFQPO from XTE J1550–564. By adaptively decomposing the ∼4-Hz oscillatory component from the light curve and acquiring its instantaneous frequency, the Hilbert spectrum illustrates that the LFQPO is composed of a series of intermittent oscillations appearing occasionally between 3 and 5more » Hz. We further characterized this intermittency by computing the confidence limits of the instantaneous amplitudes of the intermittent oscillations, and constructed both the distributions of the QPO’s high- and low-amplitude durations, which are the time intervals with and without significant ∼4-Hz oscillations, respectively. The mean high-amplitude duration is 1.45 s and 90% of the oscillation segments have lifetimes below 3.1 s. The mean low-amplitude duration is 0.42 s and 90% of these segments are shorter than 0.73 s. In addition, these intermittent oscillations exhibit a correlation between the oscillation’s rms amplitude and mean count rate. This correlation could be analogous to the linear rms-flux relation found in the 4-Hz LFQPO through Fourier analysis. We conclude that the LFQPO peak in the power spectrum is broadened owing to intermittent oscillations with varying frequencies, which could be explained by using the Lense–Thirring precession model.« less

Energy spectrum analysis - A model of echolocation processing. [in animals

NASA Technical Reports Server (NTRS)

Johnson, R. A.; Titlebaum, E. L.

1976-01-01

The paper proposes a frequency domain approach based on energy spectrum analysis of the combination of a signal and its echoes as the processing mechanism for the echolocation process used by bats and other animals. The mechanism is a generalized wide-band one and can account for the large diversity of wide-band signals used for orientation. The coherency in the spectrum of the signal-echo combination is shown to be equivalent to correlation.

Global examination of the wind-dependence of very low frequency underwater ambient noise.

PubMed

Nichols, Stephen M; Bradley, David L

2016-03-01

Ocean surface winds play a key role in underwater ambient noise generation. One particular frequency band of interest is the infrasonic or very low frequency (VLF) band from 1 to 20 Hz. In this spectral band, wind generated ocean surface waves interact non-linearly to produce acoustic waves, which couple into the seafloor to generate microseisms, as explained by the theory developed by Longuet-Higgins. This study examines long term data sets in the VLF portion of the ambient noise spectrum, collected by the hydroacoustic systems of the Comprehensive Nuclear-Test Ban Treaty Organization in the Atlantic, Pacific, and Indian Oceans. Three properties of the noise field were examined: (a) the behavior of the acoustic spectrum slope from 1 to 5 Hz, (b) correlation of noise levels and wind speeds, and (c) the autocorrelation behavior of both the noise field and the wind. Analysis results indicate the spectrum slope is site dependent, and for both correlation methods, a high correlation between wind and the noise field in the 1-5 Hz band.

Analysis of Anatomic and Functional Measures in X-Linked Retinoschisis

PubMed Central

Cukras, Catherine A.; Huryn, Laryssa A.; Jeffrey, Brett P.; Turriff, Amy; Sieving, Paul A.

2018-01-01

Purpose To examine the symmetry of structural and functional parameters between eyes in patients with X-linked retinoschisis (XLRS), as well as changes in visual acuity and electrophysiology over time. Methods This is a single-center observational study of 120 males with XLRS who were evaluated at the National Eye Institute. Examinations included best-corrected visual acuity for all participants, as well as ERG recording and optical coherence tomography (OCT) on a subset of participants. Statistical analyses were performed using nonparametric Spearman correlations and linear regression. Results Our analyses demonstrated a statistically significant correlation of structural and functional measures between the two eyes of XLRS patients for all parameters. OCT central macular thickness (n = 78; Spearman r = 0.83, P < 0.0001) and ERG b/a ratio (n = 78; Spearman r = 0.82, P < 0.0001) were the most strongly correlated between a participant's eyes, whereas visual acuity was less strongly correlated (n = 120; Spearman r = 0.47, P < 0.0001). Stability of visual acuity was observed with an average change of less than one letter (n = 74; OD −0.66 and OS −0.70 letters) in a mean follow-up time of 6.8 years. There was no statistically significant change in the ERG b/a ratio within eyes over time. Conclusions Although a broad spectrum of clinical phenotypes is observed across individuals with XLRS, our study demonstrates a significant correlation of structural and functional findings between the two eyes and stability of measures of acuity and ERG parameters over time. These results highlight the utility of the fellow eye as a useful reference for monocular interventional trials.

Modeling 13.3nm Fe XXIII Flare Emissions Using the GOES-R EXIS Instrument

NASA Astrophysics Data System (ADS)

Rook, H.; Thiemann, E.

2017-12-01

The solar EUV spectrum is dominated by atomic transitions in ionized atoms in the solar atmosphere. As solar flares evolve, plasma temperatures and densities change, influencing abundances of various ions, changing intensities of different EUV wavelengths observed from the sun. Quantifying solar flare spectral irradiance is important for constraining models of Earth's atmosphere, improving communications quality, and controlling satellite navigation. However, high time cadence measurements of flare irradiance across the entire EUV spectrum were not available prior to the launch of SDO. The EVE MEGS-A instrument aboard SDO collected 0.1nm EUV spectrum data from 2010 until 2014, when the instrument failed. No current or future instrument is capable of similar high resolution and time cadence EUV observation. This necessitates a full EUV spectrum model to study EUV phenomena at Earth. It has been recently demonstrated that one hot flare EUV line, such as the 13.3nm Fe XXIII line, can be used to model cooler flare EUV line emissions, filling the role of MEGS-A. Since unblended measurements of Fe XXIII are typically unavailable, a proxy for the Fe XXIII line must be found. In this study, we construct two models of this line, first using the GOES 0.1-0.8nm soft x-ray (SXR) channel as the Fe XXIII proxy, and second using a physics-based model dependent on GOES emission measure and temperature data. We determine that the more sophisticated physics-based model shows better agreement with Fe XXIII measurements, although the simple proxy model also performs well. We also conclude that the high correlation between Fe XXIII emissions and the GOES 0.1-0.8nm band is because both emissions tend to peak near the GOES emission measure peak despite large differences in their contribution functions.

Mid-latitude ionospheric irregularity spectral density as determined by ground-based GPS receiver networks

DOE PAGES

Lay, Erin H.; Parker, Peter A.; Light, Max; ...

2018-05-22

In this paper, we present a new technique to experimentally measure the spatial spectrum of ionospheric disturbances in the spatial scale regime of 40 – 200 km. This technique produces a 2-dimensional (2-D) spectrum for each time snapshot over two dense GPS receiver networks (GEONET in Japan and PBO in the Western U.S.). Because this technique created the spectrum from an instantaneous time snapshot, no assumptions are needed about the speed of ionospheric irregularities. We examine spectra from three days: one with an intense geomagnetic storm, one with significant lightning activity, and one quiet day. Radial slices along the 2-Dmore » spectra provide 1-dimensional spectra that can be fit to a power law to quantify the steepness of the fall-off in the spatial scale sizes. Continuous data of this type in a stationary location allows monitoring the variability in the 2-D spectrum over the course of a day and comparing between days, as shown here, or even over a year or many years. We find that the spectra are highly variable over the course of a day and between the two selected regions of Japan and the Western U.S. When strong travelling ionospheric disturbances (TIDs) are present, the 2-D spectra provide information about the direction of propagation of the TIDs. We compare the TID propagation direction with horizontal wind directions from the Horizontal Wind Model. Finally, TID direction is correlated with the horizontal wind direction on all days, strongly indicating that the primary source of the TIDs measured by this technique is tropospheric.« less

Interpretation of monoclinic hafnia valence electron energy-loss spectra by time-dependent density functional theory

NASA Astrophysics Data System (ADS)

Hung, L.; Guedj, C.; Bernier, N.; Blaise, P.; Olevano, V.; Sottile, F.

2016-04-01

We present the valence electron energy-loss spectrum and the dielectric function of monoclinic hafnia (m -HfO2) obtained from time-dependent density-functional theory (TDDFT) predictions and compared to energy-filtered spectroscopic imaging measurements in a high-resolution transmission-electron microscope. Fermi's golden rule density-functional theory (DFT) calculations can capture the qualitative features of the energy-loss spectrum, but we find that TDDFT, which accounts for local-field effects, provides nearly quantitative agreement with experiment. Using the DFT density of states and TDDFT dielectric functions, we characterize the excitations that result in the m -HfO2 energy-loss spectrum. The sole plasmon occurs between 13 and 16 eV, although the peaks ˜28 and above 40 eV are also due to collective excitations. We furthermore elaborate on the first-principles techniques used, their accuracy, and remaining discrepancies among spectra. More specifically, we assess the influence of Hf semicore electrons (5 p and 4 f ) on the energy-loss spectrum, and find that the inclusion of transitions from the 4 f band damps the energy-loss intensity in the region above 13 eV. We study the impact of many-body effects in a DFT framework using the adiabatic local-density approximation (ALDA) exchange-correlation kernel, as well as from a many-body perspective using "scissors operators" matched to an ab initio G W calculation to account for self-energy corrections. These results demonstrate some cancellation of errors between self-energy and excitonic effects, even for excitations from the Hf 4 f shell. We also simulate the dispersion with increasing momentum transfer for plasmon and collective excitation peaks.

Mid-latitude ionospheric irregularity spectral density as determined by ground-based GPS receiver networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lay, Erin H.; Parker, Peter A.; Light, Max

In this paper, we present a new technique to experimentally measure the spatial spectrum of ionospheric disturbances in the spatial scale regime of 40 – 200 km. This technique produces a 2-dimensional (2-D) spectrum for each time snapshot over two dense GPS receiver networks (GEONET in Japan and PBO in the Western U.S.). Because this technique created the spectrum from an instantaneous time snapshot, no assumptions are needed about the speed of ionospheric irregularities. We examine spectra from three days: one with an intense geomagnetic storm, one with significant lightning activity, and one quiet day. Radial slices along the 2-Dmore » spectra provide 1-dimensional spectra that can be fit to a power law to quantify the steepness of the fall-off in the spatial scale sizes. Continuous data of this type in a stationary location allows monitoring the variability in the 2-D spectrum over the course of a day and comparing between days, as shown here, or even over a year or many years. We find that the spectra are highly variable over the course of a day and between the two selected regions of Japan and the Western U.S. When strong travelling ionospheric disturbances (TIDs) are present, the 2-D spectra provide information about the direction of propagation of the TIDs. We compare the TID propagation direction with horizontal wind directions from the Horizontal Wind Model. Finally, TID direction is correlated with the horizontal wind direction on all days, strongly indicating that the primary source of the TIDs measured by this technique is tropospheric.« less

Simultaneous Monitoring of X-ray and Radio Variability in Sagittarius A*

NASA Astrophysics Data System (ADS)

Haggard, Daryl; Capellupo, Daniel M.; Choux, Nicolas; Baganoff, Frederick K.; Bower, Geoffrey C.; Cotton, William D.; Degenaar, Nathalie; Dexter, Jason; Falcke, Heino; Fragile, P. Christopher Christopher; Heinke, Craig O.; Law, Casey J.; Markoff, Sera; Neilsen, Joseph; Ponti, Gabriele; Rea, Nanda; Yusef-Zadeh, Farhad

2017-08-01

We report on joint X-ray/radio campaigns targeting Sagittarius A*, including 9 contemporaneous Chandra and VLA observations. These campaigns are the most extensive of their kind and have allowed us to test whether the black hole’s variations in different parts of the electromagnetic spectrum are due to the same physical processes. We detect significant radio variability peaking >176 minutes after the brightest X-ray flare ever detected from Sgr A*. We also identify other potentially associated X-ray and radio variability, with radio peaks appearing <80 minutes after weaker X-ray flares. These results suggest that stronger X-ray flares lead to longer time lags in the radio. However, we also test the possibility that the variability at X-ray and at radio wavelengths are not temporally correlated, and show that the radio variations occurring around the time of X-ray flaring are not significantly greater than the overall radio flux variations. We also cross-correlate data from mismatched X-ray and radio epochs and obtain comparable correlations to the matched data. Hence, we find no overall statistical evidence that X-ray flares and radio variability are correlated, underscoring a need for more simultaneous, long duration X-ray-radio monitoring of Sgr A*.

[Reducing maternal parenting stress of children with autism spectrum disorder: father's involvement].

PubMed

Hu, C C; Li, Y; Zhou, B R; Liu, C X; Li, C Y; Zhang, Y; Xu, Q; Xu, X

2017-05-04

Objective: To explore the relationship between fathers' nursing time and maternal parenting stress of children with autism spectrum disorder(ASD). Method: Mothers of 98 ASD children who were first diagnosed in the department of Child Health Care, Children's Hospital of Fudan University during June 2015 to January 2016 were included in the ASD group, with mothers of 92 typical children from a Community Maternal and Child Health Hospital and a kindergarten in the control group. The evaluation of parenting stress, parents' nursing time and other related factors were cross-sectionally analyzed. Interview was conducted with the following tools: Parental Stress Index-Short Form(PSI-SF)for maternal parenting stress, and self-made General Parenting Information Questionnaire for nursing time of both parents and other related factors. The relationships were analyzed by Multiple Linear Regression analysis and Wilcoxon Rank-Sum test. Result: Maternal parenting stress of ASD children had a significant negative correlation with father's nursing time in total score of parenting stress, PCDI domain and PD domain ( t =-2.76, -2.98, -2.79; P =0.007, 0.004, 0.006), within which PD domain also included family annual income and mothers' nursing time ( R (2)=0.22, 0.24, 0.25); while no such correlation was found in control group in terms of father's nursing time( P =0.22, 0.42, 0.06). Wilcoxon Rank-Sum test showed that in 62 (63.3%) double-income ASD families and 72(78.3%) double-income typical families, there were significant differences between ASD fathers' and ASD mothers'and typical fathers'nursing time(2.0(0.5, 2.1) vs . 3.5(2.4, 6.0) vs . 3.0(2.0, 4.7)h, t =-86.32、-49.65, all P <0.01). Conclusion: Lack of fathers' involvements was common in ASD children's families. Increasing these fathers' nursing time, as well as their enthusiasm and initiative in the family intervention could relieve maternal parenting stress and improve the intervention pattern of ASD children.

Gravitational Lensing Effect on the Two-Point Correlation of Hot Spots in the Cosmic Microwave Background.

PubMed

Takada; Komatsu; Futamase

2000-04-20

We investigate the weak gravitational lensing effect that is due to the large-scale structure of the universe on two-point correlations of local maxima (hot spots) in the two-dimensional sky map of the cosmic microwave background (CMB) anisotropy. According to the Gaussian random statistics, as most inflationary scenarios predict, the hot spots are discretely distributed, with some characteristic angular separations on the last scattering surface that are due to oscillations of the CMB angular power spectrum. The weak lensing then causes pairs of hot spots, which are separated with the characteristic scale, to be observed with various separations. We found that the lensing fairly smooths out the oscillatory features of the two-point correlation function of hot spots. This indicates that the hot spot correlations can be a new statistical tool for measuring the shape and normalization of the power spectrum of matter fluctuations from the lensing signatures.

No Evidence of Reaction Time Slowing in Autism Spectrum Disorder

ERIC Educational Resources Information Center

Ferraro, F. Richard

2016-01-01

A total of 32 studies comprising 238 simple reaction time and choice reaction time conditions were examined in individuals with autism spectrum disorder (n?=?964) and controls (n?=?1032). A Brinley plot/multiple regression analysis was performed on mean reaction times, regressing autism spectrum disorder performance onto the control performance as…

The detection error of thermal test low-frequency cable based on M sequence correlation algorithm

NASA Astrophysics Data System (ADS)

Wu, Dongliang; Ge, Zheyang; Tong, Xin; Du, Chunlin

2018-04-01

The problem of low accuracy and low efficiency of off-line detecting on thermal test low-frequency cable faults could be solved by designing a cable fault detection system, based on FPGA export M sequence code(Linear feedback shift register sequence) as pulse signal source. The design principle of SSTDR (Spread spectrum time-domain reflectometry) reflection method and hardware on-line monitoring setup figure is discussed in this paper. Testing data show that, this detection error increases with fault location of thermal test low-frequency cable.

Fluorescence lifetime imaging of skin cancer

NASA Astrophysics Data System (ADS)

Patalay, Rakesh; Talbot, Clifford; Munro, Ian; Breunig, Hans Georg; König, Karsten; Alexandrov, Yuri; Warren, Sean; Neil, Mark A. A.; French, Paul M. W.; Chu, Anthony; Stamp, Gordon W.; Dunsby, Chris

2011-03-01

Fluorescence intensity imaging and fluorescence lifetime imaging microscopy (FLIM) using two photon microscopy (TPM) have been used to study tissue autofluorescence in ex vivo skin cancer samples. A commercially available system (DermaInspect®) was modified to collect fluorescence intensity and lifetimes in two spectral channels using time correlated single photon counting and depth-resolved steady state measurements of the fluorescence emission spectrum. Uniquely, image segmentation has been used to allow fluorescence lifetimes to be calculated for each cell. An analysis of lifetime values obtained from a range of pigmented and non-pigmented lesions will be presented.

Space-Time Correlations and Spectra of Wall Pressure in a Turbulent Boundary Layer

NASA Technical Reports Server (NTRS)

Willmarth, W. W.

1959-01-01

Measurements of the statistical properties of the fluctuating wall pressure produced by a subsonic turbulent boundary layer are described. The measurements provide additional information about the structure of the turbulent boundary layer; they are applicable to the problems of boundary-layer induced noise inside an airplane fuselage and to the generation of waves-on water. The spectrum of the wall pressure is presented in dimensionless form. The ratio of the root-mean-square wall pressure to the free-stream dynamic pressure is found to be a constant square root of bar P(sup 2)/q(sub infinity) = 0.006 independent of Mach number and Reynolds number. In addition, space- time correlation measurements in the stream direction show that pressure fluctuations whose scale is greater than or equal to 0.3 times the boundary-layer thickness are convected with the convection speed U(sub c) = 0.82U(sub infinity) where U(infinity) is the free-stream velocity and have lost their identity in a distance approximately equal to 10 boundary-layer thicknesses.

Computing Wigner distributions and time correlation functions using the quantum thermal bath method: application to proton transfer spectroscopy.

PubMed

Basire, Marie; Borgis, Daniel; Vuilleumier, Rodolphe

2013-08-14

Langevin dynamics coupled to a quantum thermal bath (QTB) allows for the inclusion of vibrational quantum effects in molecular dynamics simulations at virtually no additional computer cost. We investigate here the ability of the QTB method to reproduce the quantum Wigner distribution of a variety of model potentials, designed to assess the performances and limits of the method. We further compute the infrared spectrum of a multidimensional model of proton transfer in the gas phase and in solution, using classical trajectories sampled initially from the Wigner distribution. It is shown that for this type of system involving large anharmonicities and strong nonlinear coupling to the environment, the quantum thermal bath is able to sample the Wigner distribution satisfactorily and to account for both zero point energy and tunneling effects. It leads to quantum time correlation functions having the correct short-time behavior, and the correct associated spectral frequencies, but that are slightly too overdamped. This is attributed to the classical propagation approximation rather than the generation of the quantized initial conditions themselves.

Smoothed Spectra, Ogives, and Error Estimates for Atmospheric Turbulence Data

NASA Astrophysics Data System (ADS)

Dias, Nelson Luís

2018-01-01

A systematic evaluation is conducted of the smoothed spectrum, which is a spectral estimate obtained by averaging over a window of contiguous frequencies. The technique is extended to the ogive, as well as to the cross-spectrum. It is shown that, combined with existing variance estimates for the periodogram, the variance—and therefore the random error—associated with these estimates can be calculated in a straightforward way. The smoothed spectra and ogives are biased estimates; with simple power-law analytical models, correction procedures are devised, as well as a global constraint that enforces Parseval's identity. Several new results are thus obtained: (1) The analytical variance estimates compare well with the sample variance calculated for the Bartlett spectrum and the variance of the inertial subrange of the cospectrum is shown to be relatively much larger than that of the spectrum. (2) Ogives and spectra estimates with reduced bias are calculated. (3) The bias of the smoothed spectrum and ogive is shown to be negligible at the higher frequencies. (4) The ogives and spectra thus calculated have better frequency resolution than the Bartlett spectrum, with (5) gradually increasing variance and relative error towards the low frequencies. (6) Power-law identification and extraction of the rate of dissipation of turbulence kinetic energy are possible directly from the ogive. (7) The smoothed cross-spectrum is a valid inner product and therefore an acceptable candidate for coherence and spectral correlation coefficient estimation by means of the Cauchy-Schwarz inequality. The quadrature, phase function, coherence function and spectral correlation function obtained from the smoothed spectral estimates compare well with the classical ones derived from the Bartlett spectrum.

Wigner time delay and spin-orbit activated confinement resonances

NASA Astrophysics Data System (ADS)

Keating, D. A.; Deshmukh, P. C.; Manson, S. T.

2017-09-01

A study of the photoionization of spin-orbit split subshells of high-Z atoms confined in C60 has been performed using the relativistic-random-phase approximation. Specifically, Hg@C60 5p, Rn@C60 6p and Ra@C60 5d were investigated and the near-threshold confinement resonances in the j = l - 1/2 channels were found to engender structures in the j = l + 1/2 cross sections via correlation in the form of interchannel coupling. These structures are termed spin-orbit induced confinement resonances and they are found to profoundly influence the Wigner time delay spectrum resulting in time delays of tens or hundreds of attoseconds along with dramatic swings in time delay over small energy intervals. Pronounced relativistic effects in time delay are also found. These structures, including their manifestation in time delay spectra, are expected to be general phenomena in the photoionization of spin-orbit doublets in confined high-Z atoms.

Diffusion with stochastic resetting at power-law times.

PubMed

Nagar, Apoorva; Gupta, Shamik

2016-06-01

What happens when a continuously evolving stochastic process is interrupted with large changes at random intervals τ distributed as a power law ∼τ^{-(1+α)};α>0? Modeling the stochastic process by diffusion and the large changes as abrupt resets to the initial condition, we obtain exact closed-form expressions for both static and dynamic quantities, while accounting for strong correlations implied by a power law. Our results show that the resulting dynamics exhibits a spectrum of rich long-time behavior, from an ever-spreading spatial distribution for α<1, to one that is time independent for α>1. The dynamics has strong consequences on the time to reach a distant target for the first time; we specifically show that there exists an optimal α that minimizes the mean time to reach the target, thereby offering a step towards a viable strategy to locate targets in a crowded environment.

Rapid 3D NMR using the filter diagonalization method: application to oligosaccharides derivatized with 13C-labeled acetyl groups

NASA Astrophysics Data System (ADS)

Armstrong, Geoffrey S.; Cano, Kristin E.; Mandelshtam, Vladimir A.; Shaka, A. J.; Bendiak, Brad

2004-09-01

Rapid 3D NMR spectroscopy of oligosaccharides having isotopically labeled acetyl "isotags" was made possible with high resolution in the indirect dimensions using the filter diagonalization method (FDM). A pulse sequence was designed for the optimal correlation of acetyl methyl protons, methyl carbons, and carbonyl carbons. The multi-dimensional nature of the FDM, coupled with the advantages of constant-time evolution periods, resulted in marked improvements over Fourier transform (FT) and mirror-image linear prediction (MI-LP) processing methods. The three methods were directly compared using identical data sets. A highly resolved 3D spectrum was achieved with the FDM using a very short experimental time (28 min).

Rapid 3D NMR using the filter diagonalization method: application to oligosaccharides derivatized with 13C-labeled acetyl groups.

PubMed

Armstrong, Geoffrey S; Cano, Kristin E; Mandelshtam, Vladimir A; Shaka, A J; Bendiak, Brad

2004-09-01

Rapid 3D NMR spectroscopy of oligosaccharides having isotopically labeled acetyl "isotags" was made possible with high resolution in the indirect dimensions using the filter diagonalization method (FDM). A pulse sequence was designed for the optimal correlation of acetyl methyl protons, methyl carbons, and carbonyl carbons. The multi-dimensional nature of the FDM, coupled with the advantages of constant-time evolution periods, resulted in marked improvements over Fourier transform (FT) and mirror-image linear prediction (MI-LP) processing methods. The three methods were directly compared using identical data sets. A highly resolved 3D spectrum was achieved with the FDM using a very short experimental time (28 min).

Correlation between audible noise and corona current generated by AC corona discharge in time and frequency domains

NASA Astrophysics Data System (ADS)

Li, Xuebao; Wang, Jing; Li, Yinfei; Zhang, Qian; Lu, Tiebing; Cui, Xiang

2018-06-01

Corona-generated audible noise is induced by the collisions between space charges and air molecules. It has been proven that there is a close correlation between audible noise and corona current from DC corona discharge. Analysis on the correlation between audible noise and corona current can promote the cognition of the generation mechanism of corona discharge. In this paper, time-domain waveforms of AC corona-generated audible noise and corona current are measured simultaneously. The one-to-one relationship between sound pressure pulses and corona current pulses can be found and is used to remove the interferences from background noise. After the interferences are removed, the linear correlated relationships between sound pressure pulse amplitude and corona current pulse amplitude are obtained through statistical analysis. Besides, frequency components at the harmonics of power frequency (50 Hz) can be found both in the frequency spectrums of audible noise and corona current through frequency analysis. Furthermore, the self-correlation relationships between harmonic components below 400 Hz with the 50 Hz component are analyzed for audible noise and corona current and corresponding empirical formulas are proposed to calculate the harmonic components based on the 50 Hz component. Finally, based on the AC corona discharge process and generation mechanism of audible noise and corona current, the correlation between audible noise and corona current in time domain and frequency domain are interpreted qualitatively. Besides, with the aid of analytical expressions of periodic square waves, sound pressure pulses, and corona current pulses, the modulation effects from the AC voltage on the pulse trains are used to interpret the generation of the harmonic components of audible noise and corona current.

Physiological correlates of mental workload

NASA Technical Reports Server (NTRS)

Zacharias, G. L.

1980-01-01

A literature review was conducted to assess the basis of and techniques for physiological assessment of mental workload. The study findings reviewed had shortcomings involving one or more of the following basic problems: (1) physiologic arousal can be easily driven by nonworkload factors, confounding any proposed metric; (2) the profound absence of underlying physiologic models has promulgated a multiplicity of seemingly arbitrary signal processing techniques; (3) the unspecified multidimensional nature of physiological "state" has given rise to a broad spectrum of competing noncommensurate metrics; and (4) the lack of an adequate definition of workload compels physiologic correlations to suffer either from the vagueness of implicit workload measures or from the variance of explicit subjective assessments. Using specific studies as examples, two basic signal processing/data reduction techniques in current use, time and ensemble averaging are discussed.

Longitudinal patterns of employment and postsecondary education for adults with autism and average-range IQ

PubMed Central

Taylor, Julie Lounds; Henninger, Natalie A.; Mailick, Marsha R.

2015-01-01

This study examined correlates of participation in postsecondary education (PSE) and employment over 12 years for 73 adults with autism spectrum disorders (ASD) and average-range IQ whose families were part of a larger, longitudinal study. Correlates included demographic (sex, maternal education, paternal education), behavioral (activities of daily living, maladaptive behaviors, autism symptoms) and family (size of maternal social network; maternal depressive symptoms, anxiety, and pessimism) factors. Although two-thirds of adults with ASD participated in competitive employment/PSE during the study, fewer than 25% maintained these activities over the study period. Behavioral characteristics distinguished those who never had competitive employment/PSE from those who sometimes or consistently participated in these activities. Women were considerably less likely than men to maintain employment/PSE over time. PMID:26019306

Correlation of individual differences in schizotypal personality traits with amphetamine-induced dopamine release in striatal and extrastriatal brain regions.

PubMed

Woodward, Neil D; Cowan, Ronald L; Park, Sohee; Ansari, M Sib; Baldwin, Ronald M; Li, Rui; Doop, Mikisha; Kessler, Robert M; Zald, David H

2011-04-01

Schizotypal personality traits are associated with schizophrenia spectrum disorders, and individuals with schizophrenia spectrum disorders demonstrate increased dopamine transmission in the striatum. The authors sought to determine whether individual differences in normal variation in schizotypal traits are correlated with dopamine transmission in the striatum and in extrastriatal brain regions. Sixty-three healthy volunteers with no history of psychiatric illness completed the Schizotypal Personality Questionnaire and underwent positron emission tomography imaging with [(18)F]fallypride at baseline and after administration of oral d-amphetamine (0.43 mg/kg). Dopamine release, quantified by subtracting each participant's d-amphetamine scan from his or her baseline scan, was correlated with Schizotypal Personality Questionnaire total and factor scores using region-of-interest and voxel-wise analyses. Dopamine release in the striatum was positively correlated with overall schizotypal traits. The association was especially robust in the associative subdivision of the striatum. Voxel-wise analyses identified additional correlations between dopamine release and schizotypal traits in the left middle frontal gyrus and left supramarginal gyrus. Exploratory analyses of Schizotypal Personality Questionnaire factor scores revealed correlations between dopamine release and disorganized schizotypal traits in the striatum, thalamus, medial prefrontal cortex, temporal lobe, insula, and inferior frontal cortex. The association between dopamine signaling and psychosis phenotypes extends to individual differences in normal variation in schizotypal traits and involves dopamine transmission in both striatal and extrastriatal brain regions. Amphetamine-induced dopamine release may be a useful endophenotype for investigating the genetic basis of schizophrenia spectrum disorders.

School Functions in Unaffected Siblings of Youths with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Chien, Yi-Ling; Tu, En-Nien; Gau, Susan Shur-Fen

2017-01-01

This study investigated school functioning among unaffected siblings of youths with autistic spectrum disorder (ASD) and identified the correlates for school maladjustment. We recruited 66 youths with a clinical diagnosis of ASD, aged 8-19, their unaffected siblings and 132 typically developing controls (TD). We found that ASD youths had poorer…

ERP Correlates of Recognition Memory in Autism Spectrum Disorder

ERIC Educational Resources Information Center

Massand, Esha; Bowler, Dermot M.; Mottron, Laurent; Hosein, Anthony; Jemel, Boutheina

2013-01-01

Recognition memory in autism spectrum disorder (ASD) tends to be undiminished compared to that of typically developing (TD) individuals (Bowler et al. 2007), but it is still unknown whether memory in ASD relies on qualitatively similar or different neurophysiology. We sought to explore the neural activity underlying recognition by employing the…

Neural Correlates of Pragmatic Language Comprehension in Autism Spectrum Disorders

ERIC Educational Resources Information Center

Tesink, C. M. J. Y.; Buitelaar, J. K.; Petersson, K. M.; van der Gaag, R. J.; Kan, C. C.; Tendolkar, I.; Hagoort, P.

2009-01-01

Difficulties with pragmatic aspects of communication are universal across individuals with autism spectrum disorders (ASDs). Here we focused on an aspect of pragmatic language comprehension that is relevant to social interaction in daily life: the integration of speaker characteristics inferred from the voice with the content of a message. Using…

Seizures and Epilepsy and Their Relationship to Autism Spectrum Disorders

ERIC Educational Resources Information Center

Matson, Johnny L.; Neal, Daniene

2009-01-01

Autism spectrum disorders (ASD) are serious neurodevelopmental disorders which often co-occur with intellectual disabilities. A disorder which is strongly correlated with both of these disabilities are seizures and epilepsy. The purpose of this review was to provide an overview of available research on seizures and epilepsy in the ASD population…

Cardiac Reactivity and Stimulant Use in Adolescents with Autism Spectrum Disorders with Comorbid ADHD Versus ADHD

ERIC Educational Resources Information Center

Bink, M.; Popma, A.; Bongers, I. L.; van Boxtel, G. J. M.; Denissen, A.; van Nieuwenhuizen, Ch.

2015-01-01

A large number of youngsters with autism spectrum disorders (ASD) display comorbid attention deficit/hyperactivity disorder (ADHD) symptoms. However, previous studies are not conclusive whether psychophysiological correlates, like cardiac reactivity, are different for ASD with comorbid ADHD (ASD+) compared to ADHD. Therefore, the current study…

Physical Aggression in Children and Adolescents with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Mazurek, Micah O.; Kanne, Stephen M.; Wodka, Ericka L.

2013-01-01

Aggression is a clinically significant problem for many children and adolescents with autism spectrum disorders (ASD). However, there have been few large-scale studies addressing this issue. The current study examined the prevalence and correlates of physical aggression in a sample of 1584 children and adolescents with ASD enrolled in the Autism…

Prevalence and Correlates of Screen-Based Media Use among Youths with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Mazurek, Micah O.; Shattuck, Paul T.; Wagner, Mary; Cooper, Benjamin P.

2012-01-01

Anecdotal reports indicate that individuals with autism spectrum disorders (ASD) are often preoccupied with television, computers, and video games (screen-based media). However, few studies have examined this issue. The current study examined screen-based media use among a large, nationally representative sample of youths participating in the…

Word Processing in Children with Autism Spectrum Disorders: Evidence from Event-Related Potentials

ERIC Educational Resources Information Center

Sandbank, Michael; Yoder, Paul; Key, Alexandra P.

2017-01-01

Purpose: This investigation was conducted to determine whether young children with autism spectrum disorders exhibited a canonical neural response to word stimuli and whether putative event-related potential (ERP) measures of word processing were correlated with a concurrent measure of receptive language. Additional exploratory analyses were used…

Supervision of Children with an Autism Spectrum Disorder in the Context of Unintentional injury

ERIC Educational Resources Information Center

Cavalari, Rachel N. S.; Romanczyk, Raymond G.

2012-01-01

Despite high rates of severe medically attended injuries, a thorough understanding of the correlates of injury for children with an autism spectrum disorder (ASD) is currently lacking. The present study sought to determine the effect of an ASD diagnosis, self-reported supervision styles, and supervisor characteristics on behavioral supervisory…

BROADBAND TIME-RESOLVED E{sub p,i}-L{sub iso} CORRELATION IN GAMMA-RAY BURSTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frontera, F.; Guidorzi, C.; Amati, L.

We report the results of a systematic study of the broadband (2-2000 keV) time-resolved prompt emission spectra of a sample of gamma-ray bursts (GRBs) detected with both Wide Field Cameras on board the BeppoSAX satellite and the BATSE experiment on board CGRO. In this first paper, we study the time-resolved dependence of the intrinsic peak energy E{sub p,i} of the E F(E) spectrum on the corresponding isotropic bolometric luminosity L{sub iso}. The E{sub p,i}-L{sub iso} relation or the equivalent relation between E{sub p,i} and the bolometric released energy E{sub iso}, derived using the time-averaged spectra of long GRBs with knownmore » redshift, is well established, but its physical origin is still a subject of discussion. In addition, some authors maintain that these relations are the result of instrumental selection effects. We find that not only a relation between the measured peak energy E{sub p} and the corresponding energy flux, but also a strong E{sub p,i} versus L{sub iso} correlation are found not only within each burst, but also are merging together the time-resolved data points from different GRBs. We do not expect significant instrumental selection effects that can affect the results obtained, apart from the fact that the GRBs in our sample are sufficiently bright to perform a time-resolved spectroscopy and that they have known redshift. If the fundamental physical process that gives rise to the GRB phenomenon does not depend on its brightness, we conclude that the E{sub p,i} versus L{sub iso} correlation found within each GRB is intrinsic to the emission process and that the correlations discovered by Amati et al. and Yonetoku et al. are likely not the result of selection effects. We also discuss the properties of the correlations found.« less

Statistical Analysis of Large Scale Structure by the Discrete Wavelet Transform

NASA Astrophysics Data System (ADS)

Pando, Jesus

1997-10-01

The discrete wavelet transform (DWT) is developed as a general statistical tool for the study of large scale structures (LSS) in astrophysics. The DWT is used in all aspects of structure identification including cluster analysis, spectrum and two-point correlation studies, scale-scale correlation analysis and to measure deviations from Gaussian behavior. The techniques developed are demonstrated on 'academic' signals, on simulated models of the Lymanα (Lyα) forests, and on observational data of the Lyα forests. This technique can detect clustering in the Ly-α clouds where traditional techniques such as the two-point correlation function have failed. The position and strength of these clusters in both real and simulated data is determined and it is shown that clusters exist on scales as large as at least 20 h-1 Mpc at significance levels of 2-4 σ. Furthermore, it is found that the strength distribution of the clusters can be used to distinguish between real data and simulated samples even where other traditional methods have failed to detect differences. Second, a method for measuring the power spectrum of a density field using the DWT is developed. All common features determined by the usual Fourier power spectrum can be calculated by the DWT. These features, such as the index of a power law or typical scales, can be detected even when the samples are geometrically complex, the samples are incomplete, or the mean density on larger scales is not known (the infrared uncertainty). Using this method the spectra of Ly-α forests in both simulated and real samples is calculated. Third, a method for measuring hierarchical clustering is introduced. Because hierarchical evolution is characterized by a set of rules of how larger dark matter halos are formed by the merging of smaller halos, scale-scale correlations of the density field should be one of the most sensitive quantities in determining the merging history. We show that these correlations can be completely determined by the correlations between discrete wavelet coefficients on adjacent scales and at nearly the same spatial position, Cj,j+12/cdot2. Scale-scale correlations on two samples of the QSO Ly-α forests absorption spectra are computed. Lastly, higher order statistics are developed to detect deviations from Gaussian behavior. These higher order statistics are necessary to fully characterize the Ly-α forests because the usual 2nd order statistics, such as the two-point correlation function or power spectrum, give inconclusive results. It is shown how this technique takes advantage of the locality of the DWT to circumvent the central limit theorem. A non-Gaussian spectrum is defined and this spectrum reveals not only the magnitude, but the scales of non-Gaussianity. When applied to simulated and observational samples of the Ly-α clouds, it is found that different popular models of structure formation have different spectra while two, independent observational data sets, have the same spectra. Moreover, the non-Gaussian spectra of real data sets are significantly different from the spectra of various possible random samples. (Abstract shortened by UMI.)

Reconstruction of Rayleigh-Lamb dispersion spectrum based on noise obtained from an air-jet forcing.

PubMed

Larose, Eric; Roux, Philippe; Campillo, Michel

2007-12-01

The time-domain cross correlation of incoherent and random noise recorded by a series of passive sensors contains the impulse response of the medium between these sensors. By using noise generated by a can of compressed air sprayed on the surface of a plexiglass plate, we are able to reconstruct not only the time of flight but the whole wave forms between the sensors. From the reconstruction of the direct A(0) and S(0) waves, we derive the dispersion curves of the flexural waves, thus estimating the mechanical properties of the material without a conventional electromechanical source. The dense array of receivers employed here allow a precise frequency-wavenumber study of flexural waves, along with a thorough evaluation of the rate of convergence of the correlation with respect to the record length, the frequency, and the distance between the receivers. The reconstruction of the actual amplitude and attenuation of the impulse response is also addressed in this paper.

Transient Spectra in TDDFT: Corrections and Correlations

NASA Astrophysics Data System (ADS)

Parkhill, John; Nguyen, Triet

We introduce an atomistic, all-electron, black-box electronic structure code to simulate transient absorption (TA) spectra and apply it to simulate pyrazole and a GFP chromophore derivative. The method is an application of OSCF2, our dissipative extension of time-dependent density functional theory. We compare our simulated spectra directly with recent ultra-fast spectroscopic experiments, showing that they are usefully predicted. We also relate bleaches in the TA signal to Fermi-blocking which would be missed in a simplified model. An important ingredient in the method is the stationary-TDDFT correction scheme recently put forwards by Fischer, Govind, and Cramer which allows us to overcome a limitation of adiabatic TDDFT. We demonstrate that OSCF2 is able to predict both the energies of bleaches and induced absorptions, as well as the decay of the transient spectrum, with only the molecular structure as input. With remaining time we will discuss corrections which resolve the non-resonant behavior of driven TDDFT, and correlated corrections to mean-field dynamics.

Homogeneous time-resolved G protein-coupled receptor-ligand binding assay based on fluorescence cross-correlation spectroscopy.

PubMed

Antoine, Thomas; Ott, David; Ebell, Katharina; Hansen, Kerrin; Henry, Luc; Becker, Frank; Hannus, Stefan

2016-06-01

G protein-coupled receptors (GPCRs) mediate many important physiological functions and are considered as one of the most successful therapeutic target classes for a wide spectrum of diseases. Drug discovery projects generally benefit from a broad range of experimental approaches for screening compound libraries and for the characterization of binding modes of drug candidates. Owing to the difficulties in solubilizing and purifying GPCRs, assay formats have been so far mainly limited to cell-based functional assays and radioligand binding assays. In this study, we used fluorescence cross-correlation spectroscopy (FCCS) to analyze the interaction of detergent-solubilized receptors to various types of GPCR ligands: endogenous peptides, small molecules, and a large surrogate antagonist represented by a blocking monoclonal antibody. Our work demonstrates the suitability of the homogeneous and time-resolved FCCS assay format for a robust, high-throughput determination of receptor-ligand binding affinities and kinetic rate constants for various therapeutically relevant GPCRs. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

[Spectrum-Effect Relationship of GualouXiebai Dropping Pills on Myocardial Ischemia].

PubMed

Yan, Hai-yan; Zou, Chun-cai; Wei, Mei-ling; Yang, You-yun; Fei, Fu-qi; Xu, Xin-ying

2015-09-01

To study the relationship between HPLC characteristic spectrum and pharmacodynamics on anti-myocardial ischemia of GualouXiebai dropping pills. HPLC characteristic spectrum of GualouXiebai dropping pills was established, dropping pills were divided into five dose groups (3.75, 11.25, 22.5, 33.75 and 45 g/kg, equivalent to the crude herb g/kg), the mice were orally administered dropping pills once daily for 7 d, 90 min after the mice were given by intraperitoneal injection of isoprenaline to establish myocardial ischemia models, the level of CK in blood plasma were detected; Then, the correlation between characteristic spectrum and biochemical index CK was studied by grey relational analysis method. The correlation between each common peak and CK had gradually increased with the dose increased from 3.73 g/kg to 33.75 g/kg, but when the dose reached to 45 g/kg, the correlation between each common peak and CK had decreased. The variation trends of correlation of spectrum-effect relationship for different dose were similar,but the correlation variation trend of the efficacy on the No. 8 peak in 33.75 g/kg group with the other four groups in the opposite, the change trends of the No. 11 peak in 22.5 g/kg group, the No. 24 peak in 33. 75 g/kg group and the No. 37 peak in 45 g/ kg group with 3.75 g/kg group and 11.25 g/kg group on the contrary. The relational orders of spectrum-effect relationship were not consistent, respectively( the first 15 peaks) :11 > 37 > 24 > 30 > 8 > 21 > 2 > 16 > 1 > 3 > 20 > 15 > 12 > 19 > 7;11 > 37 > 30 > 8 > 21 > 24 > 2 > 1 > 16 > 3 > 27 > 12 > 22 > 20 >10; 8 > 30 > 1 > 2 > 21 > 27 > 31 > 22 > 16 > 12 > 3 > 10 > 9 > 20 > 4; 1 > 2 > 27 > 21 > 31 > 22 > 12 > 16 > 9 > 3 > 10 > 4 > 17 > 30 > 20; 8 > 30 > 1 > 2 > 2 > 2 > 7 > 31 > 22 > 16 > 12 > 3 > 9 > 10 > 20 > 17. Anti-myocardial ischemia effect of GualouXiebai dropping pills comes from the synergistic or antagonistic effect among various active ingredients related to the dose. With the difference of the dosage, the relational orders of chemical components to play the role is not the same, but the main components to play a pharmacodynamic of five dose groups are consistent,the existence of the component groups lay a foundation for further study of GualouXiebai dropping pills.

Improving “color rendering” of LED lighting for the growth of lettuce

NASA Astrophysics Data System (ADS)

Han, Tao; Vaganov, Vitaliy; Cao, Shixiu; Li, Qiang; Ling, Lili; Cheng, Xiaoyao; Peng, Lingling; Zhang, Congzhi; Yakovlev, Alexey N.; Zhong, Yang; Tu, Mingjing

2017-04-01

Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve “color rendering” of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 μmol·m-2·s-1 for a 16 hd-1 photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were investigated. We let the absorption spectrum of fresh leaf be the emission spectrum of ideal light and then evaluate the “color rendering” of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates. Under the irradiation of red-yellow-blue light with high correlation coefficient of 0.587, the dry weights and leaf growth rate are 2-3 times as high as the sharp red-blue light. The optimized LED light for lettuce growth can be presumed to be limited to the angle (about 75°) between the vectors passed through the ideal light in the CIE chromaticity coordinates. These findings open up a new idea to assess and find the optimized LED light for plant growth.

Parametric spectro-temporal analyzer (PASTA) for ultrafast optical performance monitoring

NASA Astrophysics Data System (ADS)

Zhang, Chi; Wong, Kenneth K. Y.

2013-12-01

Ultrafast optical spectrum monitoring is one of the most challenging tasks in observing ultrafast phenomena, such as the spectroscopy, dynamic observation of the laser cavity, and spectral encoded imaging systems. However, conventional method such as optical spectrum analyzer (OSA) spatially disperses the spectrum, but the space-to-time mapping is realized by mechanical rotation of a grating, so are incapable of operating at high speed. Besides the spatial dispersion, temporal dispersion provided by dispersive fiber can also stretches the spectrum in time domain in an ultrafast manner, but is primarily confined in measuring short pulses. In view of these constraints, here we present a real-time spectrum analyzer called parametric spectro-temporal analyzer (PASTA), which is based on the time-lens focusing mechanism. It achieves a 100-MHz frame rate and can measure arbitrary waveforms. For the first time, we observe the dynamic spectrum of an ultrafast swept-source: Fourier domain mode-locked (FDML) laser, and the spectrum evolution of a laser cavity during its stabilizing process. In addition to the basic single-lens structure, the multi-lens configurations (e.g. telescope or wide-angle scope) will provide a versatile operating condition, which can zoom in to achieve 0.05-nm resolution and zoom out to achieve 10-nm observation range, namely 17 times zoom in/out ratio. In view of the goal of achieving spectrum analysis with fine accuracy, PASTA provides a promising path to study the real-time spectrum of some dynamic phenomena and non-repetitive events, with orders of magnitude enhancement in the frame rate over conventional OSAs.

Spectral reflectance characteristics of different snow and snow-covered land surface objects and mixed spectrum fitting

USGS Publications Warehouse

Zhang, J.-H.; Zhou, Z.-M.; Wang, P.-J.; Yao, F.-M.; Yang, L.

2011-01-01

The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area. The result showed that for a pure snow spectrum, the snow reflectance peaks appeared from visible to 800 nm band locations; there was an obvious absorption valley of snow spectrum near 1030 nm wavelength. Compared with fresh snow, the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300~1300, 1700~1800 and 2200~2300 nm, the lowest was from the compacted snow and frozen ice. For the vegetation and snow mixed spectral characteristics, it was indicated that the spectral reflectance increased for the snow-covered land types(including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350~1300 nm. However, the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic. In the end, based on the spectrum analysis of snow, vegetation, and mixed snow/vegetation pixels, the mixed spectral fitting equations were established, and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones(correlation coefficient R2=0.9509).

Spectral statistics of random geometric graphs

NASA Astrophysics Data System (ADS)

Dettmann, C. P.; Georgiou, O.; Knight, G.

2017-04-01

We use random matrix theory to study the spectrum of random geometric graphs, a fundamental model of spatial networks. Considering ensembles of random geometric graphs we look at short-range correlations in the level spacings of the spectrum via the nearest-neighbour and next-nearest-neighbour spacing distribution and long-range correlations via the spectral rigidity Δ3 statistic. These correlations in the level spacings give information about localisation of eigenvectors, level of community structure and the level of randomness within the networks. We find a parameter-dependent transition between Poisson and Gaussian orthogonal ensemble statistics. That is the spectral statistics of spatial random geometric graphs fits the universality of random matrix theory found in other models such as Erdős-Rényi, Barabási-Albert and Watts-Strogatz random graphs.

Lack of small-scale clustering in 21-cm intensity maps crossed with 2dF galaxy densities at z ~ 0.08

NASA Astrophysics Data System (ADS)

Anderson, Christopher; Luciw, Nicholas; Li, Yi-Chao; Kuo, Cheng-Yu; Yadav, Jaswant; Masui, Kiyoshi; Chang, Tzu-Ching; Chen, Xuelei; Oppermann, Niels; Pen, Ue-Li; Timbie, Peter T.

2017-06-01

I report results from 21-cm intensity maps acquired from the Parkes radio telescope and cross-correlated with galaxy maps from the 2dF galaxy survey. The data span the redshift range 0.057

Recovering information of tunneling spectrum from weakly isolated horizon

NASA Astrophysics Data System (ADS)

Chen, Ge-Rui; Huang, Yong-Chang

2015-02-01

In this paper we investigate the properties of tunneling spectrum from weakly isolated horizon (WIH)—a locally defined black hole. We find that there exist correlations among Hawking radiations from a WIH, information can be carried out by such correlations, and the radiation is an entropy conservation process. Through revisiting the calculation of the tunneling spectrum from a WIH, we find that Zhang et al.'s (Ann Phys 326:350, 2011) requirement that radiated particles have the same angular momenta of a unit mass as that of the black hole is unnecessary, and the energy and angular momenta of the emitted particles are very arbitrary, restricted only by keeping the cosmic censorship hypothesis of black holes. So we resolve the information loss paradox based on the method of Zhang et al. (Phys Lett B 675:98, 2009; Ann Phys 326:350, 2011; Int J Mod Phys D 22:1341014, 2013) in a general case.

Cross-spectrum measurement of thermal-noise limited oscillators.

PubMed

Hati, A; Nelson, C W; Howe, D A

2016-03-01

Cross-spectrum analysis is a commonly used technique for the detection of phase and amplitude noise of a signal in the presence of interfering uncorrelated noise. Recently, we demonstrated that the phase-inversion (anti-correlation) effect due to amplitude noise leakage can cause complete or partial collapse of the cross-spectral function. In this paper, we discuss the newly discovered effect of anti-correlated thermal noise that originates from the common-mode power divider (splitter), an essential component in a cross-spectrum noise measurement system. We studied this effect for different power splitters and discuss its influence on the measurement of thermal-noise limited oscillators. We provide theory, simulation and experimental results. In addition, we expand this study to reveal how the presence of ferrite-isolators and amplifiers at the output ports of the power splitters can affect the oscillator noise measurements. Finally, we discuss a possible solution to overcome this problem.

Sensory over-responsivity in adults with autism spectrum conditions.

PubMed

Tavassoli, Teresa; Miller, Lucy J; Schoen, Sarah A; Nielsen, Darci M; Baron-Cohen, Simon

2014-05-01

Anecdotal reports and empirical evidence suggest that sensory processing issues are a key feature of autism spectrum conditions. This study set out to investigate whether adults with autism spectrum conditions report more sensory over-responsivity than adults without autism spectrum conditions. Another goal of the study was to identify whether autistic traits in adults with and without autism spectrum conditions were associated with sensory over-responsivity. Adults with (n = 221) and without (n = 181) autism spectrum conditions participated in an online survey. The Autism Spectrum Quotient, the Raven Matrices and the Sensory Processing Scale were used to characterize the sample. Adults with autism spectrum conditions reported more sensory over-responsivity than control participants across various sensory domains (visual, auditory, tactile, olfactory, gustatory and proprioceptive). Sensory over-responsivity correlated positively with autistic traits (Autism Spectrum Quotient) at a significant level across groups and within groups. Adults with autism spectrum conditions experience sensory over-responsivity to daily sensory stimuli to a high degree. A positive relationship exists between sensory over-responsivity and autistic traits. Understanding sensory over-responsivity and ways of measuring it in adults with autism spectrum conditions has implications for research and clinical settings.

Metallic-thin-film instability with spatially correlated thermal noise.

PubMed

Diez, Javier A; González, Alejandro G; Fernández, Roberto

2016-01-01

We study the effects of stochastic thermal fluctuations on the instability of the free surface of a flat liquid metallic film on a solid substrate. These fluctuations are represented by a stochastic noise term added to the deterministic equation for the film thickness within the long-wave approximation. Unlike the case of polymeric films, we find that this noise, while remaining white in time, must be colored in space, at least in some regimes. The corresponding noise term is characterized by a nonzero correlation length, ℓ_{c}, which, combined with the size of the system, leads to a dimensionless parameter β that accounts for the relative importance of the spatial correlation (β∼ℓ_{c}^{-1}). We perform the linear stability analysis (LSA) of the film both with and without the noise term and find that for ℓ_{c} larger than some critical value (depending on the system size), the wavelength of the peak of the spectrum is larger than that corresponding to the deterministic case, while for smaller ℓ_{c} this peak corresponds to smaller wavelength than the latter. Interestingly, whatever the value of ℓ_{c}, the peak always approaches the deterministic one for larger times. We compare LSA results with the numerical simulations of the complete nonlinear problem and find a good agreement in the power spectra for early times at different values of β. For late times, we find that the stochastic LSA predicts well the position of the dominant wavelength, showing that nonlinear interactions do not modify the trends of the early linear stages. Finally, we fit the theoretical spectra to experimental data from a nanometric laser-melted copper film and find that at later times, the adjustment requires smaller values of β (larger space correlations).

Metallic-thin-film instability with spatially correlated thermal noise

NASA Astrophysics Data System (ADS)

Diez, Javier A.; González, Alejandro G.; Fernández, Roberto

2016-01-01

We study the effects of stochastic thermal fluctuations on the instability of the free surface of a flat liquid metallic film on a solid substrate. These fluctuations are represented by a stochastic noise term added to the deterministic equation for the film thickness within the long-wave approximation. Unlike the case of polymeric films, we find that this noise, while remaining white in time, must be colored in space, at least in some regimes. The corresponding noise term is characterized by a nonzero correlation length, ℓc, which, combined with the size of the system, leads to a dimensionless parameter β that accounts for the relative importance of the spatial correlation (β ˜ℓc-1 ). We perform the linear stability analysis (LSA) of the film both with and without the noise term and find that for ℓc larger than some critical value (depending on the system size), the wavelength of the peak of the spectrum is larger than that corresponding to the deterministic case, while for smaller ℓc this peak corresponds to smaller wavelength than the latter. Interestingly, whatever the value of ℓc, the peak always approaches the deterministic one for larger times. We compare LSA results with the numerical simulations of the complete nonlinear problem and find a good agreement in the power spectra for early times at different values of β . For late times, we find that the stochastic LSA predicts well the position of the dominant wavelength, showing that nonlinear interactions do not modify the trends of the early linear stages. Finally, we fit the theoretical spectra to experimental data from a nanometric laser-melted copper film and find that at later times, the adjustment requires smaller values of β (larger space correlations).

Picosecond time-resolved absorption and fluorescence dynamics in the artificial bacteriorhodopsin pigment BR6.11.

PubMed

Brack, T L; Delaney, J K; Atkinson, G H; Albeck, A; Sheves, M; Ottolenghi, M

1993-08-01

The picosecond molecular dynamics in an artificial bacteriorhodopsin (BR) pigment containing a structurally modified all-trans retinal chromphore with a six-membered ring bridging the C11=C12-C13 positions (BR6.11) are measured by picosecond transient absorption and picosecond time-resolved fluorescence spectroscopy. Time-dependent intensity and spectral changes in absorption in the 570-650-nm region are monitored for delays as long as 5 ns after the 7-ps, 573-nm excitation of BR6.11. Two intermediates, J6.11 and K6.11/1, both with enhanced absorption to the red (> 600 nm) of the BR6.11 spectrum are observed within approximately 50 ps. The J6.11 intermediate decays with a time constant of 12 +/- 3 ps to form K6.11/1. The K6.11/1 intermediate decays with an approximately 100-ps time constant to form a third intermediate, K6.11/2, which is observed through diminished 650-nm absorption (relative to that of K6.11/1). No other transient absorption changes are found during the remainder of the initial 5-ns period of the BR6.11 photoreaction. Fluorescence in the 650-900-nm region is observed from BR6.11, K6.11/1, and K6.11/2, but no emission assignable to J6.11 is found. The BR6.11 fluroescence spectrum has a approximately 725-nm maximum which is blue-shifted by approximately 15 nm relative to that of native BR-570 and is 4.2 +/- 1.5 times larger in intensity (same sample optical density). No differences in the profile of the fluorescence spectra of BR6.11 and the intermediates K6.11/1 and K6.11/2 are observed. Following ground-state depletion of the BR6.11 population, the time-resolved fluroescence intensity monitored at 725 nm increases with two time constants, 12 +/- 3 and approximately 100 ps, both of which correlate well with changes in the picosecond transient absorption data. The resonance Raman spectrum of ground-state BR6.11, measured with low-energy, 560-nm excitation, is significantly different from the spectrum of native BR-570, thus confirming that the picosecond transient absorption and picosecond time resolved fluorescence data are assignable to BR6.11 and its photoreaction alone and not to BR-570 reformed during there constitution process (<5% of the BR6.11 sample could be attributed to native BR-570).The J6.11 and K6.11 absorption and fluorescence data presented here are generally analogous to those measured for native J-625 and K-590, respectively, and therefore, the primary events in the BR6.11 photoreaction can be correlated with those in the native BR photocycle. The BR6.11 photoreaction, however, exhibits important differences including slower formation rates for J and K intermediates as well as the presence of a second K intermediate. These results demonstrate that the restricted motion in the C11=C12-C13 region of retinal found in BR6.11 does not greatly change the overall photoreaction mechanism,but does alter the rates at which processes occur.

The Solar Spectral Irradiance as a Function of the Mg II Index for Atmosphere and Climate Modelling

NASA Technical Reports Server (NTRS)

Thuillier, Gerard; DeLand, Matthew; Shapiro, Alexander; Schmutz, Werner; Bolsee, David; Melo, Stella

2011-01-01

In this paper we present a new method to reconstruct the solar spectrum irradiance in the Ly alpha-400 nm region, and its variability, based on the Mg II index and neutron monitor. Measurements of the solar spectral irradiance available in the literature have been made with different instruments at different times and different spectral ranges. However, climate studies require harmonized data sets. This new approach has the advantage of being independent of the absolute calibration and aging of the instruments. First, the Mg II index is derived using solar spectra from Ly alpha (121 nm) to 410 nm measured from 1978 to 2010 by several space missions. The variability of the spectra with respect to a chosen reference spectrum as a function of time and wavelength is scaled to the derived Mg II index. The set of coefficients expressing the spectral variability can be applied to the chosen reference spectrum to reconstruct the solar spectra within a given time frame or Mg II index values. The accuracy of this method is estimated using two approaches: by direct comparison with particular cases where solar spectra are available from independent measurements, and by calculating the standard deviation between the measured spectra and their reconstruction. From direct comparisons with measurements we obtain an accuracy of about 1 to 2 %, which degrades towards Ly alpha. In a further step, we extend our solar spectral irradiance reconstruction back to the Maunder Minimum introducing the relationship between the Mg II index and the neutron monitor data. Consistent measurements of the Mg II index are not available prior to 1978. However, we observe that over the last three solar cycles, the Mg II index shows strong correlation with the modulation potential determined from the neutron monitor data. Assuming that this correlation can be applied to the past, we reconstruct the Mg II index from the modulation potential back to the Maunder Minimum, and obtain the corresponding solar spectral irradiance reconstruction back to that period. As there is no direct measurement of the spectral irradiance for this period we discuss this methodology in light of the other proposed approaches available in the literature. The use of the cosmogenic isotope data provides a major advantage: it provides information about the solar activity over several thousands years. Using technology of today we can calibrate the solar irradiance against the activity and thus reconstruct it for the times when cosmogenic isotope data are available. This calibration can be re-accessed at any time, if necessary.

A phenotypic structure and neural correlates of compulsive behaviors in adolescents.

PubMed

Montigny, Chantale; Castellanos-Ryan, Natalie; Whelan, Robert; Banaschewski, Tobias; Barker, Gareth J; Büchel, Christian; Gallinat, Jürgen; Flor, Herta; Mann, Karl; Paillère-Martinot, Marie-Laure; Nees, Frauke; Lathrop, Mark; Loth, Eva; Paus, Tomas; Pausova, Zdenka; Rietschel, Marcella; Schumann, Gunter; Smolka, Michael N; Struve, Maren; Robbins, Trevor W; Garavan, Hugh; Conrod, Patricia J

2013-01-01

A compulsivity spectrum has been hypothesized to exist across Obsessive-Compulsive disorder (OCD), Eating Disorders (ED), substance abuse (SA) and binge-drinking (BD). The objective was to examine the validity of this compulsivity spectrum, and differentiate it from an externalizing behaviors dimension, but also to look at hypothesized personality and neural correlates. A community-sample of adolescents (N=1938; mean age 14.5 years), and their parents were recruited via high-schools in 8 European study sites. Data on adolescents' psychiatric symptoms, DSM diagnoses (DAWBA) and substance use behaviors (AUDIT and ESPAD) were collected through adolescent- and parent-reported questionnaires and interviews. The phenotypic structure of compulsive behaviors was then tested using structural equation modeling. The model was validated using personality variables (NEO-FFI and TCI), and Voxel-Based Morphometry (VBM) analysis. Compulsivity symptoms best fit a higher-order two factor model, with ED and OCD loading onto a compulsivity factor, and BD and SA loading onto an externalizing factor, composed also of ADHD and conduct disorder symptoms. The compulsivity construct correlated with neuroticism (r=0.638; p ≤ 0.001), conscientiousness (r=0.171; p ≤ 0.001), and brain gray matter volume in left and right orbitofrontal cortex, right ventral striatum and right dorsolateral prefrontal cortex. The externalizing factor correlated with extraversion (r=0.201; p ≤ 0.001), novelty-seeking (r=0.451; p ≤ 0.001), and negatively with gray matter volume in the left inferior and middle frontal gyri. Results suggest that a compulsivity spectrum exists in an adolescent, preclinical sample and accounts for variance in both OCD and ED, but not substance-related behaviors, and can be differentiated from an externalizing spectrum.

A Phenotypic Structure and Neural Correlates of Compulsive Behaviors in Adolescents

PubMed Central

Montigny, Chantale; Castellanos-Ryan, Natalie; Whelan, Robert; Banaschewski, Tobias; Barker, Gareth J.; Büchel, Christian; Gallinat, Jürgen; Flor, Herta; Mann, Karl; Paillère-Martinot, Marie-Laure; Nees, Frauke; Lathrop, Mark; Loth, Eva; Paus, Tomas; Pausova, Zdenka; Rietschel, Marcella; Schumann, Gunter; Smolka, Michael N.; Struve, Maren; Robbins, Trevor W.; Garavan, Hugh; Conrod, Patricia J.

2013-01-01

Background A compulsivity spectrum has been hypothesized to exist across Obsessive-Compulsive disorder (OCD), Eating Disorders (ED), substance abuse (SA) and binge-drinking (BD). The objective was to examine the validity of this compulsivity spectrum, and differentiate it from an externalizing behaviors dimension, but also to look at hypothesized personality and neural correlates. Method A community-sample of adolescents (N=1938; mean age 14.5 years), and their parents were recruited via high-schools in 8 European study sites. Data on adolescents’ psychiatric symptoms, DSM diagnoses (DAWBA) and substance use behaviors (AUDIT and ESPAD) were collected through adolescent- and parent-reported questionnaires and interviews. The phenotypic structure of compulsive behaviors was then tested using structural equation modeling. The model was validated using personality variables (NEO-FFI and TCI), and Voxel-Based Morphometry (VBM) analysis. Results Compulsivity symptoms best fit a higher-order two factor model, with ED and OCD loading onto a compulsivity factor, and BD and SA loading onto an externalizing factor, composed also of ADHD and conduct disorder symptoms. The compulsivity construct correlated with neuroticism (r=0.638; p≤0.001), conscientiousness (r=0.171; p≤0.001), and brain gray matter volume in left and right orbitofrontal cortex, right ventral striatum and right dorsolateral prefrontal cortex. The externalizing factor correlated with extraversion (r=0.201; p≤0.001), novelty-seeking (r=0.451; p≤0.001), and negatively with gray matter volume in the left inferior and middle frontal gyri. Conclusions Results suggest that a compulsivity spectrum exists in an adolescent, preclinical sample and accounts for variance in both OCD and ED, but not substance-related behaviors, and can be differentiated from an externalizing spectrum. PMID:24244633

[Atmospheric parameter estimation for LAMOST/GUOSHOUJING spectra].

PubMed

Lu, Yu; Li, Xiang-Ru; Yang, Tan

2014-11-01

It is a key task to estimate the atmospheric parameters from the observed stellar spectra in exploring the nature of stars and universe. With our Large Sky Area Multi-Object Fiber Spectroscopy Telescope (LAMOST) which begun its formal Sky Survey in September 2012, we are obtaining a mass of stellar spectra in an unprecedented speed. It has brought a new opportunity and a challenge for the research of galaxies. Due to the complexity of the observing system, the noise in the spectrum is relatively large. At the same time, the preprocessing procedures of spectrum are also not ideal, such as the wavelength calibration and the flow calibration. Therefore, there is a slight distortion of the spectrum. They result in the high difficulty of estimating the atmospheric parameters for the measured stellar spectra. It is one of the important issues to estimate the atmospheric parameters for the massive stellar spectra of LAMOST. The key of this study is how to eliminate noise and improve the accuracy and robustness of estimating the atmospheric parameters for the measured stellar spectra. We propose a regression model for estimating the atmospheric parameters of LAMOST stellar(SVM(lasso)). The basic idea of this model is: First, we use the Haar wavelet to filter spectrum, suppress the adverse effects of the spectral noise and retain the most discrimination information of spectrum. Secondly, We use the lasso algorithm for feature selection and extract the features of strongly correlating with the atmospheric parameters. Finally, the features are input to the support vector regression model for estimating the parameters. Because the model has better tolerance to the slight distortion and the noise of the spectrum, the accuracy of the measurement is improved. To evaluate the feasibility of the above scheme, we conduct experiments extensively on the 33 963 pilot surveys spectrums by LAMOST. The accuracy of three atmospheric parameters is log Teff: 0.006 8 dex, log g: 0.155 1 dex, [Fe/H]: 0.104 0 dex.

The bright future of single-molecule fluorescence imaging

PubMed Central

Juette, Manuel F.; Terry, Daniel S.; Wasserman, Michael R.; Zhou, Zhou; Altman, Roger B.; Zheng, Qinsi; Blanchard, Scott C.

2014-01-01

Single-molecule Förster resonance energy transfer (smFRET) is an essential and maturing tool to probe biomolecular interactions and conformational dynamics in vitro and, increasingly, in living cells. Multi-color smFRET enables the correlation of multiple such events and the precise dissection of their order and timing. However, the requirements for good spectral separation, high time resolution, and extended observation times place extraordinary demands on the fluorescent labels used in such experiments. Together with advanced experimental designs and data analysis, the development of long-lasting, non-fluctuating fluorophores is therefore proving key to progress in the field. Recently developed strategies for obtaining ultra-stable organic fluorophores spanning the visible spectrum are underway that will enable multi-color smFRET studies to deliver on their promise of previously unachievable biological insights. PMID:24956235

Metal spectra as indicators of development.

PubMed

Graedel, T E; Cao, J

2010-12-07

We have assembled extensive information on the cycles of seven industrial metals in 49 countries, territories, or groups of countries, drawn from a database of some 200,000 material flows, and have devised analytical approaches to treat the suite of metals as composing an approach to a national "materials metabolism." We demonstrate that in some of the more developed countries, per capita metal use is more than 10 times the global average. Additionally, countries that use more than the per capita world average of any metal do so for all metals, and vice versa, and countries that are above global average rates of use are very likely to be above global average rates at all stages of metal life cycles from fabrication onward. We show that all countries are strongly dependent on international trade to supply the spectrum of nonrenewable resources that modern technology requires, regardless of their level of development. We also find that the rate of use of the spectrum of metals stock is highly correlated to per capita gross domestic product, as well as to the Human Development Index and the Global Competitiveness Innovation Index. The implication is that as wealth and technology increase in developing countries, strong demand will be created not for a few key resources, but across the entire spectrum of the industrial metals. Long-term metal demand can be estimated given gross domestic product projections; the results suggest overall metal flow into use in 2050 of 5-10 times today's level should supplies permit.

Metal spectra as indicators of development

PubMed Central

Graedel, T. E.; Cao, J.

2010-01-01

We have assembled extensive information on the cycles of seven industrial metals in 49 countries, territories, or groups of countries, drawn from a database of some 200,000 material flows, and have devised analytical approaches to treat the suite of metals as composing an approach to a national “materials metabolism.” We demonstrate that in some of the more developed countries, per capita metal use is more than 10 times the global average. Additionally, countries that use more than the per capita world average of any metal do so for all metals, and vice versa, and countries that are above global average rates of use are very likely to be above global average rates at all stages of metal life cycles from fabrication onward. We show that all countries are strongly dependent on international trade to supply the spectrum of nonrenewable resources that modern technology requires, regardless of their level of development. We also find that the rate of use of the spectrum of metals stock is highly correlated to per capita gross domestic product, as well as to the Human Development Index and the Global Competitiveness Innovation Index. The implication is that as wealth and technology increase in developing countries, strong demand will be created not for a few key resources, but across the entire spectrum of the industrial metals. Long-term metal demand can be estimated given gross domestic product projections; the results suggest overall metal flow into use in 2050 of 5–10 times today’s level should supplies permit. PMID:21098309

Beta Pic-like Circumstellar Gas Disk Around 2 And

NASA Technical Reports Server (NTRS)

Cheng, Patricia

2003-01-01

This grant was awarded to support the data analysis and publication of results from our project entitled P Pic-like Circumstellar Gas Disk Around 2 And . We proposed to obtain FUSE observations of 2 And and study the characteristics and origin of its circumstellar gas. We observed 2 Andromedae with FUSE on 3-4 July 2001 in 11 exposures with a total exposure time of 21,289 seconds through the LWRS aperture. Our data were calibrated with Version 1.8.7 of the CALFUSE pipeline processing software. We corrected the wavelength scale for the heliocentric velocity error in this version of the CALFUSE software. The relative accuracy of the calibrated wavelength scale is +/- 9 km/s . We produced a co-added spectrum in the LiF 1B and LiF 2A channels (covering the 1100 to 1180 A region) by cross-correlating the 11 individual exposures and doing an exposure-time weighted average flux. The final co-added spectra have a signal-to-noise ratio in the stellar continuum near 1150 A of about 20. To obtain an absolute wavelength calibration, we cross-correlated our observed spectra with a model spectrum to obtain the best fit for the photospheric C I lines. Because the photospheric lines are very broad, this yields an absolute accuracy for the wavelength scale of approx.+/- 15 km/s. We then rebinned 5 original pixels to yield the optimal sampling of .033 A for each new pixel, because the calibrated spectra oversample the spectral resolution for FUSE+LWRS (R = 20,000 +/- 2,000).

X-Ray and UV Orbital Phase Dependence in LMC X-3

NASA Technical Reports Server (NTRS)

Dolan, Joseph F.; Boyd, P. T.; Smale, A. P.

2001-01-01

The black-hole binary LMC X-3 is known to be variable on time scales of days to years. We investigated X-ray and ultraviolet variability in the system as a function of the 1.7 d binary orbit using a 6.4 day observation with the Rossi X-ray Timing Explorer (RXTE) in 1998 December. An abrupt 14 % flux decrease lasting nearly an entire orbit was followed by a return to previous flux levels. This behavior occurred twice at nearly the same binary phase, but is not present in consecutive orbits. When the X-ray flux is at lower intensity, a periodic amplitude modulation of 7 % is evident in data folded modulo the orbital period. The higher intensity data show weaker correlation with phase. This is the first report of X-ray variability at the orbital period of LMC X-3. Archival RXTE observations of LMC X-3 during a high flux state in 1996 December show similar phase dependence. An ultraviolet light curve obtained with the High Speed Photometer (HSP) on the Hubble Space Telescope (HST) shows a phase dependent variability consistent with that observed in the visible, ascribed to the ellipsoidal variation of the visible star. The X-ray spectrum of LMC X-3 is acceptably represented by a phenomenological disk black-body plus a power law. Changes in the spectrum of LMX X-3 during our observations are compatible with earlier observations during which variations in the 2-10 keV flux are closely correlated with the disk geometry spectral model parameter.

Intact mirror mechanisms for automatic facial emotions in children and adolescents with autism spectrum disorder.

PubMed

Schulte-Rüther, Martin; Otte, Ellen; Adigüzel, Kübra; Firk, Christine; Herpertz-Dahlmann, Beate; Koch, Iring; Konrad, Kerstin

2017-02-01

It has been suggested that an early deficit in the human mirror neuron system (MNS) is an important feature of autism. Recent findings related to simple hand and finger movements do not support a general dysfunction of the MNS in autism. Studies investigating facial actions (e.g., emotional expressions) have been more consistent, however, mostly relied on passive observation tasks. We used a new variant of a compatibility task for the assessment of automatic facial mimicry responses that allowed for simultaneous control of attention to facial stimuli. We used facial electromyography in 18 children and adolescents with Autism spectrum disorder (ASD) and 18 typically developing controls (TDCs). We observed a robust compatibility effect in ASD, that is, the execution of a facial expression was facilitated if a congruent facial expression was observed. Time course analysis of RT distributions and comparison to a classic compatibility task (symbolic Simon task) revealed that the facial compatibility effect appeared early and increased with time, suggesting fast and sustained activation of motor codes during observation of facial expressions. We observed a negative correlation of the compatibility effect with age across participants and in ASD, and a positive correlation between self-rated empathy and congruency for smiling faces in TDC but not in ASD. This pattern of results suggests that basic motor mimicry is intact in ASD, but is not associated with complex social cognitive abilities such as emotion understanding and empathy. Autism Res 2017, 10: 298-310. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Random Matrix Theory and Econophysics

NASA Astrophysics Data System (ADS)

Rosenow, Bernd

2000-03-01

Random Matrix Theory (RMT) [1] is used in many branches of physics as a ``zero information hypothesis''. It describes generic behavior of different classes of systems, while deviations from its universal predictions allow to identify system specific properties. We use methods of RMT to analyze the cross-correlation matrix C of stock price changes [2] of the largest 1000 US companies. In addition to its scientific interest, the study of correlations between the returns of different stocks is also of practical relevance in quantifying the risk of a given stock portfolio. We find [3,4] that the statistics of most of the eigenvalues of the spectrum of C agree with the predictions of RMT, while there are deviations for some of the largest eigenvalues. We interpret these deviations as a system specific property, e.g. containing genuine information about correlations in the stock market. We demonstrate that C shares universal properties with the Gaussian orthogonal ensemble of random matrices. Furthermore, we analyze the eigenvectors of C through their inverse participation ratio and find eigenvectors with large ratios at both edges of the eigenvalue spectrum - a situation reminiscent of localization theory results. This work was done in collaboration with V. Plerou, P. Gopikrishnan, T. Guhr, L.A.N. Amaral, and H.E Stanley and is related to recent work of Laloux et al.. 1. T. Guhr, A. Müller Groeling, and H.A. Weidenmüller, ``Random Matrix Theories in Quantum Physics: Common Concepts'', Phys. Rep. 299, 190 (1998). 2. See, e.g. R.N. Mantegna and H.E. Stanley, Econophysics: Correlations and Complexity in Finance (Cambridge University Press, Cambridge, England, 1999). 3. V. Plerou, P. Gopikrishnan, B. Rosenow, L.A.N. Amaral, and H.E. Stanley, ``Universal and Nonuniversal Properties of Cross Correlations in Financial Time Series'', Phys. Rev. Lett. 83, 1471 (1999). 4. V. Plerou, P. Gopikrishnan, T. Guhr, B. Rosenow, L.A.N. Amaral, and H.E. Stanley, ``Random Matrix Theory Analysis of Diffusion in Stock Price Dynamics, preprint

The cross-correlation between 21 cm intensity mapping maps and the Lyα forest in the post-reionization era

NASA Astrophysics Data System (ADS)

Carucci, Isabella P.; Villaescusa-Navarro, Francisco; Viel, Matteo

2017-04-01

We investigate the cross-correlation signal between 21cm intensity mapping maps and the Lyα forest in the fully non-linear regime using state-of-the-art hydrodynamic simulations. The cross-correlation signal between the Lyα forest and 21cm maps can provide a coherent and comprehensive picture of the neutral hydrogen (HI) content of our Universe in the post-reionization era, probing both its mass content and volume distribution. We compute the auto-power spectra of both fields together with their cross-power spectrum at z = 2.4 and find that on large scales the fields are completely anti-correlated. This anti-correlation arises because regions with high (low) 21cm emission, such as those with a large (low) concentration of damped Lyα systems, will show up as regions with low (high) transmitted flux. We find that on scales smaller than k simeq 0.2 hMpc-1 the cross-correlation coefficient departs from -1, at a scale where non-linearities show up. We use the anisotropy of the power spectra in redshift-space to determine the values of the bias and of the redshift-space distortion parameters of both fields. We find that the errors on the value of the cosmological and astrophysical parameters could decrease by 30% when adding data from the cross-power spectrum, in a conservative analysis. Our results point out that linear theory is capable of reproducing the shape and amplitude of the cross-power up to rather non-linear scales. Finally, we find that the 21cm-Lyα cross-power spectrum can be detected by combining data from a BOSS-like survey together with 21cm intensity mapping observations by SKA1-MID with a S/N ratio higher than 3 in kin[0.06,1] hMpc-1. We emphasize that while the shape and amplitude of the 21cm auto-power spectrum can be severely affected by residual foreground contamination, cross-power spectra will be less sensitive to that and therefore can be used to identify systematics in the 21cm maps.

Validity of the Autism Spectrum Disorder Observation for Children (ASD-OC)

ERIC Educational Resources Information Center

Neal, Daniene; Matson, Johnny L.; Hattier, Megan A.

2014-01-01

The Autism Spectrum Disorder Observation for Children (ASD-OC) is a 45-item observation scale used to assess autistic symptomatology. The reliability of this measure has been established in previous research; therefore, the purpose of this study is to evaluate its validity among a sample of children (1-15 years). The large correlation between the…

Sex Differences in Cognitive Domains and Their Clinical Correlates in Higher-Functioning Autism Spectrum Disorders

ERIC Educational Resources Information Center

Bolte, Sven; Duketis, Eftichia; Poustka, Fritz; Holtmann, Martin

2011-01-01

Despite the skewed sex ratio, few studies have addressed possible cognitive sex differences in autism spectrum disorders (ASDs). This study compared visual attention to detail (ATTD) and selected executive functions (EF) in 35 males and 21 females with higher-functioning ASD and unaffected sibling controls. Females with ASD outperformed males on…

Atypical Processing of Gaze Cues and Faces Explains Comorbidity between Autism Spectrum Disorder (ASD) and Attention Deficit/Hyperactivity Disorder (ADHD)

ERIC Educational Resources Information Center

Groom, Madeleine J.; Kochhar, Puja; Hamilton, Antonia; Liddle, Elizabeth B.; Simeou, Marina; Hollis, Chris

2017-01-01

This study investigated the neurobiological basis of comorbidity between autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD). We compared children with ASD, ADHD or ADHD+ASD and typically developing controls (CTRL) on behavioural and electrophysiological correlates of gaze cue and face processing. We measured effects…

Validating the Repetitive Behavior Scale-Revised in Young Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Mirenda, Pat; Smith, Isabel M.; Vaillancourt, Tracy; Georgiades, Stelios; Duku, Eric; Szatmari, Peter; Bryson, Susan; Fombonne, Eric; Roberts, Wendy; Volden, Joanne; Waddell, Charlotte; Zwaigenbaum, Lonnie

2010-01-01

This study examined the factor structure of the Repetitive Behavior Scale-Revised (RBS-R) in a sample of 287 preschool-aged children with autism spectrum disorder (ASD). A confirmatory factor analysis was used to examine six competing structural models. Spearman's rank order correlations were calculated to examine the associations between factor…

Self-Injurious Behaviour in Individuals with Autism Spectrum Disorder and Intellectual Disability

ERIC Educational Resources Information Center

Richards, C.; Oliver, C.; Nelson, L.; Moss, J.

2012-01-01

Background: Autism spectrum disorder (ASD) has been identified as a risk marker for self-injurious behaviour. In this study we aimed to describe the prevalence, topography and correlates of self-injury in individuals with ASD in contrast to individuals with Fragile X and Down syndromes and examine person characteristics associated with self-injury…

Electronic absorption spectrum of copper-doped magnesium potassium phosphate hexahydrate

NASA Astrophysics Data System (ADS)

Rao, S. N.; Sivaprasad, P.; Reddy, Y. P.; Rao, P. S.

1992-04-01

The optical absorption and EPR spectra of magnesium potassium phosphate hexahydrate (MPPH) doped with copper ions are recorded both at room and liquid nitrogen temperatures. The spectrum is characteristic of Cu2+ in tetragonal symmetry. The spin-Hamiltonian parameters and molecular orbital coefficients are evaluated. A correlation between EPR and optical absorption studies is drawn.

Parent-Reported Developmental Regression in Autism: Epilepsy, IQ, Schizophrenia Spectrum Symptoms, and Special Education

ERIC Educational Resources Information Center

Gadow, Kenneth D.; Perlman, Greg; Weber, Rebecca J.

2017-01-01

Examined the psychiatric and clinical correlates of loss of previously acquired skills (regression) as reported by parents of youth with autism spectrum disorder (ASD). Study sample comprised 6- to 18-year old (N = 213) children and adolescents with ASD. Parents reported regression in 77 (36%) youth. A more homogeneous subgroup with regression…

Risk Factors for Behavioral and Emotional Difficulties in Siblings of Children with Autism Spectrum Disorder

ERIC Educational Resources Information Center

Walton, Katherine M.

2016-01-01

This study examined risk factors for behavioral and emotional problems in 1973 siblings of children with autism spectrum disorders (ASD). Results revealed six correlates of sibling internalizing and externalizing problems: male gender, smaller family size, older age of the child with ASD, lower family income, child with ASD behavior problems, and…

Dual Cognitive and Biological Correlates of Anxiety in Autism Spectrum Disorders

ERIC Educational Resources Information Center

Hollocks, Matthew J.; Pickles, Andrew; Howlin, Patricia; Simonoff, Emily

2016-01-01

Young people with autism spectrum disorder (ASD) have a high prevalence (~40 %) of anxiety disorders compared to their non-ASD peers. It is unclear whether cognitive and biological processes associated with anxiety in ASD are analogous to anxiety in typically developing (TD) populations. In this study 55 boys with ASD (34 with a co-occurring…

The Oral Narrative Comprehension and Production Abilities of Verbal Preschoolers on the Autism Spectrum

ERIC Educational Resources Information Center

Westerveld, Marleen F.; Roberts, Jacqueline M. A.

2017-01-01

Purpose: This study described the oral narrative comprehension and production skills of verbal preschool-age children on the autism spectrum and investigated correlations between oral narrative ability and norm-referenced language test performance. Method: Twenty-nine preschool-age children (aged 4;0-5;9 years;months) with autism, who obtained an…

Measurement of radionuclides in waste packages

DOEpatents

Brodzinski, R.L.; Perkins, R.W.; Rieck, H.G.; Wogman, N.A.

1984-09-12

A method is described for non-destructively assaying the radionuclide content of solid waste in a sealed container by analysis of the waste's gamma-ray spectrum and neutron emissions. Some radionuclides are measured by characteristic photopeaks in the gamma-ray spectrum; transuranic nuclides are measured by neutron emission rate; other radionuclides are measured by correlation with those already measured.

Head Circumferences in Twins with and without Autism Spectrum Disorders

ERIC Educational Resources Information Center

Froehlich, Wendy; Cleveland, Sue; Torres, Andrea; Phillips, Jennifer; Cohen, Brianne; Torigoe, Tiffany; Miller, Janet; Fedele, Angie; Collins, Jack; Smith, Karen; Lotspeich, Linda; Croen, Lisa A.; Ozonoff, Sally; Lajonchere, Clara; Grether, Judith K.; Hallmayer, Joachim

2013-01-01

To determine the genetic relationship between head circumference (HC) and Autism Spectrum Disorders (ASDs). Twin pairs with at least one twin with an ASD were assessed. HCs in affected and unaffected individuals were compared, as were HC correlations in monozygotic and dizygotic pairs. 404 subjects, ages 4-18, were included. 20% of males and 27%…

Adaptive Behavior Ratings Correlate with Symptomatology and IQ among Individuals with High-Functioning Autism Spectrum Disorders

ERIC Educational Resources Information Center

Kenworthy, Lauren; Case, Laura; Harms, Madeline B.; Martin, Alex; Wallace, Gregory L.

2010-01-01

Caregiver report on the Adaptive Behavior Assessment System-II (ABAS) for 40 high-functioning individuals with Autism Spectrum Disorders (ASD) and 30 typically developing (TD) individuals matched for age, IQ, and sex ratio revealed global adaptive behavior deficits in ASD, with social skills impairments particularly prominent. Within the ASD…

Autism Severity and Motor Abilities Correlates of Imitation Situations in Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Zachor, Ditza A.; Ilanit, Tzaig; Itzchak, Esther Ben

2010-01-01

Impaired performance in a range of imitation tasks has been described in children with autism spectrum disorders (ASD) and several underlying mechanism have been suggested. This study examined whether imitation abilities are related to autism severity and to motor skills. Furthermore, the performance of children with ASD in four imitation…

Predictors of Self-Injurious Behavior and Self-Restraint in Autism Spectrum Disorder: Towards a Hypothesis of Impaired Behavioral Control

ERIC Educational Resources Information Center

Richards, Caroline; Davies, Louise; Oliver, Chris

2017-01-01

Self-injury is common in autism spectrum disorder (ASD); however few studies have investigated correlates of self-injury or the putative associations with self-restraint. Questionnaire data on self-injury, self-restraint, health conditions, overactivity/impulsivity and repetitive/restricted behavior were collected on 208 children and 216 adults…

An Italian Prospective Experience on the Association between Congenital Cytomegalovirus Infection and Autistic Spectrum Disorder

ERIC Educational Resources Information Center

Garofoli, Francesca; Lombardi, Giuseppina; Orcesi, Simona; Pisoni, Camilla; Mazzucchelli, Iolanda; Angelini, Micol; Balottin, Umberto; Stronati, Mauro

2017-01-01

The aim of this retrospective study, with prospective data collection, was to correlate congenital cytomegalovirus (CMV) infection with autism spectrum disorder (ASD) and to define its prevalence. Seventy proven congenitally-infected infants, born between 2007 and 2012, were referred to our centre for CMV diagnosis and follow-up, which consisted…

Measurement of radionuclides in waste packages

DOEpatents

Brodzinski, Ronald L.; Perkins, Richard W.; Rieck, Henry G.; Wogman, Ned A.

1986-01-01

A method is described for non-destructively assaying the radionuclide content of solid waste in a sealed container by analysis of the waste's gamma-ray spectrum and neutron emissions. Some radionuclides are measured by characteristic photopeaks in the gamma-ray spectrum; transuranic nuclides are measured by neutron emission rate; other radionuclides are measured by correlation with those already measured.

Developmental Meta-Analysis of the Functional Neural Correlates of Autism Spectrum Disorders

ERIC Educational Resources Information Center

Dickstein, Daniel P.; Pescosolido, Matthew F.; Reidy, Brooke L.; Galvan, Thania; Kim, Kerri L.; Seymour, Karen E.; Laird, Angela R.; Di Martino, Adriana; Barrett, Rowland P.

2013-01-01

Objective: There is a pressing need to elucidate the brain-behavior interactions underlying autism spectrum disorders (ASD) given the marked rise in ASD diagnosis over the past decade. Functional magnetic resonance imaging (fMRI) has begun to address this need, but few fMRI studies have evaluated age-related changes in ASD. Therefore, we conducted…

Understanding the Origins of Dipolar Couplings and Correlated Motion in the Vibrational Spectrum of Water.

PubMed

Heyden, Matthias; Sun, Jian; Forbert, Harald; Mathias, Gerald; Havenith, Martina; Marx, Dominik

2012-08-16

The combination of vibrational spectroscopy and molecular dynamics simulations provides a powerful tool to obtain insights into the molecular details of water structure and dynamics in the bulk and in aqueous solutions. Applying newly developed approaches to analyze correlations of charge currents, molecular dipole fluctuations, and vibrational motion in real and k-space, we compare results from nonpolarizable water models, widely used in biomolecular modeling, to ab initio molecular dynamics. For the first time, we unfold the infrared response of bulk water into contributions from correlated fluctuations in the three-dimensional, anisotropic environment of an average water molecule, from the OH-stretching region down to the THz regime. Our findings show that the absence of electronic polarizability in the force field model not only results in differences in dipolar couplings and infrared absorption but also induces artifacts into the correlated vibrational motion between hydrogen-bonded water molecules, specifically at the intramolecular bending frequency. Consequently, vibrational motion is partially ill-described with implications for the accuracy of non-self-consistent, a posteriori methods to add polarizability.

47 CFR 15.323 - Specific requirements for devices operating in the 1920-1930 MHz sub-band.

Code of Federal Regulations, 2010 CFR

2010-10-01

...] (c) Devices must incorporate a mechanism for monitoring the time and spectrum windows that its... transmission, devices must monitor the combined time and spectrum windows in which they intend to transmit for... windows without further monitoring. However, occupation of the same combined time and spectrum windows by...

A theoretical description of the polarization dependence of the sum frequency generation spectroscopy of the water/vapor interface

NASA Astrophysics Data System (ADS)

Perry, Angela; Neipert, Christine; Kasprzyk, Christina Ridley; Green, Tony; Space, Brian; Moore, Preston B.

2005-10-01

An improved time correlation function (TCF) description of sum frequency generation (SFG) spectroscopy was developed and applied to theoretically describing the spectroscopy of the ambient water/vapor interface. A more general TCF expression than was published previously is presented—it is valid over the entire vibrational spectrum for both the real and imaginary parts of the signal. Computationally, earlier time correlation function approaches were limited to short correlation times that made signal processing challenging. Here, this limitation is overcome, and well-averaged spectra are presented for the three independent polarization conditions that are possible for electronically nonresonant SFG. The theoretical spectra compare quite favorably in shape and relative magnitude to extant experimental results in the O H stretching region of water for all polarization geometries. The methodological improvements also allow the calculation of intermolecular SFG spectra. While the intermolecular spectrum of bulk water shows relatively little structure, the interfacial spectra (for polarizations that are sensitive to dipole derivatives normal to the interface—SSP and PPP) show a well-defined intermolecular mode at 875cm-1 that is comparable in intensity to the rest of the intermolecular structure, and has an intensity that is approximately one-sixth of the magnitude of the intense free OH stretching peak. Using instantaneous normal mode methods, the resonance is shown to be due to a wagging mode localized on a single water molecule, almost parallel to the interface, with two hydrogens displaced normal to the interface, and the oxygen anchored in the interface. We have also uncovered the origin of another intermolecular mode at 95cm-1 for the SSP and PPP spectra, and at 220cm-1 for the SPS spectra. These resonances are due to hindered translations perpendicular to the interface for the SSP and PPP spectra, and translations parallel to the interface for the SPS spectra. Further, by examining the real and imaginary parts of the SFG signal, several resonances are shown to be due to a single spectroscopic species while the "donor" OH region is shown to consist of three distinct species—consistent with an earlier experimental analysis.

The TANAMI Multiwavelength Program: Dynamic spectral energy distributions of southern blazars

DOE PAGES

Krauß, F.; Wilms, J.; Kadler, M.; ...

2016-06-28

Simultaneous broadband spectral and temporal studies of blazars are an important tool for investigating active galactic nuclei (AGN) jet physics. Aims. Here, we study the spectral evolution between quiescent and flaring periods of 22 radio-loud AGN through multiepoch, quasi-simultaneous broadband spectra. For many of these sources these are the first broadband studies. We also use a Bayesian block analysis of Fermi/LAT light curves to determine time ranges of constant flux for constructing quasi-simultaneous spectral energy distributions (SEDs). The shapes of the resulting 81 SEDs are described by two logarithmic parabolas and a blackbody spectrum where needed. The peak frequencies andmore » luminosities agree well with the blazar sequence for low states with higher luminosity implying lower peak frequencies. This is not true for sources in high states. The γ-ray photon index in Fermi/LAT correlates with the synchrotron peak frequency in low and intermediate states. No correlation is present in high states. The black hole mass cannot be determined from the SEDs. Surprisingly, the thermal excess often found in FSRQs at optical/UV wavelengths can be described by blackbody emission and not an accretion disk spectrum. The so-called harder-when-brighter trend, typically seen in X-ray spectra of flaring blazars, is visible in the blazar sequence. Furthermore, our results for low and intermediate states, as well as the Compton dominance, are in agreement with previous results. Black hole mass estimates using recently published parameters are in agreement with some of the more direct measurements. For two sources, estimates disagree by more than four orders of magnitude, possibly owing to boosting effects. The shapes of the thermal excess seen predominantly in flat spectrum radio quasars are inconsistent with a direct accretion disk origin.« less

Only Follow-Up of Memory B Cells Helps Monitor Rituximab Administration to Patients with Neuromyelitis Optica Spectrum Disorders.

PubMed

Lebrun, Christine; Cohen, Mikael; Rosenthal-Allieri, Maria Alessandra; Bresch, Saskia; Benzaken, Sylvia; Marignier, Romain; Seitz-Polski, Barbara; Ticchioni, Michel

2018-06-07

Neuromyelitis optica spectrum disorders (NMOSD) are identified as a spectrum of inflammatory demyelinating disorders involving the brain, spinal cord and optic nerves. These disorders require early diagnosis and highly active immunosuppressive treatment. Rituximab (RTX) has demonstrated efficacy in limiting relapse in NMOSD when using several administration schedules. We questioned if the CD19+ CD27+ memory B cell count was a more reliable marker to monitor RTX administration than the RTX plasma level and CD19+ B cell count. We analyzed 125 blood samples from 17 NMOSD patients treated with RTX and also measured the level of anti-aquaporine-4 antibodies (anti-AQP-4 Abs), human anti-chimeric antibodies to the murine fragment of RTX (HACA-RTX Abs), and the RTX concentration. The mean follow-up time of the cohort was 7.4 (2-16) years. All patients improved with a mean EDSS going from 4 (1-8.5) to 2.7 (1-5.5). The mean interval between RTX infusions was 9.6 months with identification of prolonged responders. Total CD19+ B cell detection with the routine technique did not correlate to re-emergence of CD19+ CD27+ memory B cells. The RTX residual concentration did not correlate with the CD19+ CD27+ memory B cell count or with anti-RTX antibody production. In contrast to total CD19+ cell, detected with the routine technique, CD19+ CD27+ memory B cells are a reliable marker for biological relapse and allow a decrease in the frequency of infusions.

Resonances arising from hydrodynamic memory in Brownian motion.

PubMed

Franosch, Thomas; Grimm, Matthias; Belushkin, Maxim; Mor, Flavio M; Foffi, Giuseppe; Forró, László; Jeney, Sylvia

2011-10-05

Observation of the Brownian motion of a small probe interacting with its environment provides one of the main strategies for characterizing soft matter. Essentially, two counteracting forces govern the motion of the Brownian particle. First, the particle is driven by rapid collisions with the surrounding solvent molecules, referred to as thermal noise. Second, the friction between the particle and the viscous solvent damps its motion. Conventionally, the thermal force is assumed to be random and characterized by a Gaussian white noise spectrum. The friction is assumed to be given by the Stokes drag, suggesting that motion is overdamped at long times in particle tracking experiments, when inertia becomes negligible. However, as the particle receives momentum from the fluctuating fluid molecules, it also displaces the fluid in its immediate vicinity. The entrained fluid acts back on the particle and gives rise to long-range correlations. This hydrodynamic 'memory' translates to thermal forces, which have a coloured, that is, non-white, noise spectrum. One hundred years after Perrin's pioneering experiments on Brownian motion, direct experimental observation of this colour is still elusive. Here we measure the spectrum of thermal noise by confining the Brownian fluctuations of a microsphere in a strong optical trap. We show that hydrodynamic correlations result in a resonant peak in the power spectral density of the sphere's positional fluctuations, in strong contrast to overdamped systems. Furthermore, we demonstrate different strategies to achieve peak amplification. By analogy with microcantilever-based sensors, our results reveal that the particle-fluid-trap system can be considered a nanomechanical resonator in which the intrinsic hydrodynamic backflow enhances resonance. Therefore, instead of being treated as a disturbance, details in thermal noise could be exploited for the development of new types of sensor and particle-based assay in lab-on-a-chip applications.

HydroClimATe: hydrologic and climatic analysis toolkit

USGS Publications Warehouse

Dickinson, Jesse; Hanson, Randall T.; Predmore, Steven K.

2014-01-01

The potential consequences of climate variability and climate change have been identified as major issues for the sustainability and availability of the worldwide water resources. Unlike global climate change, climate variability represents deviations from the long-term state of the climate over periods of a few years to several decades. Currently, rich hydrologic time-series data are available, but the combination of data preparation and statistical methods developed by the U.S. Geological Survey as part of the Groundwater Resources Program is relatively unavailable to hydrologists and engineers who could benefit from estimates of climate variability and its effects on periodic recharge and water-resource availability. This report documents HydroClimATe, a computer program for assessing the relations between variable climatic and hydrologic time-series data. HydroClimATe was developed for a Windows operating system. The software includes statistical tools for (1) time-series preprocessing, (2) spectral analysis, (3) spatial and temporal analysis, (4) correlation analysis, and (5) projections. The time-series preprocessing tools include spline fitting, standardization using a normal or gamma distribution, and transformation by a cumulative departure. The spectral analysis tools include discrete Fourier transform, maximum entropy method, and singular spectrum analysis. The spatial and temporal analysis tool is empirical orthogonal function analysis. The correlation analysis tools are linear regression and lag correlation. The projection tools include autoregressive time-series modeling and generation of many realizations. These tools are demonstrated in four examples that use stream-flow discharge data, groundwater-level records, gridded time series of precipitation data, and the Multivariate ENSO Index.

Holding-time-aware asymmetric spectrum allocation in virtual optical networks

NASA Astrophysics Data System (ADS)

Lyu, Chunjian; Li, Hui; Liu, Yuze; Ji, Yuefeng

2017-10-01

Virtual optical networks (VONs) have been considered as a promising solution to support current high-capacity dynamic traffic and achieve rapid applications deployment. Since most of the network services (e.g., high-definition video service, cloud computing, distributed storage) in VONs are provisioned by dedicated data centers, needing different amount of bandwidth resources in both directions, the network traffic is mostly asymmetric. The common strategy, symmetric provisioning of traffic in optical networks, leads to a waste of spectrum resources in such traffic patterns. In this paper, we design a holding-time-aware asymmetric spectrum allocation module based on SDON architecture and an asymmetric spectrum allocation algorithm based on the module is proposed. For the purpose of reducing spectrum resources' waste, the algorithm attempts to reallocate the idle unidirectional spectrum slots in VONs, which are generated due to the asymmetry of services' bidirectional bandwidth. This part of resources can be exploited by other requests, such as short-time non-VON requests. We also introduce a two-dimensional asymmetric resource model for maintaining idle spectrum resources information of VON in spectrum and time domains. Moreover, a simulation is designed to evaluate the performance of the proposed algorithm, and results show that our proposed asymmetric spectrum allocation algorithm can improve the resource waste and reduce blocking probability.

Correlation between optical return loss and transmission fringe noise in high-index contrast waveguides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, Chi; Martin, Yves; Khater, Marwan

2017-05-15

We present a phenomenological model correlating optical return loss and amplitude of fringes in transmission spectrum due to distributed backscattering in high-index-contrast waveguides. The model is validated experimentally using four different waveguide cross sections.

Quantum statistics of four-wave mixing by a nonlinear resonant microcavity

NASA Astrophysics Data System (ADS)

Sherkunov, Y.; Whittaker, David M.; Schomerus, Henning; Fal'ko, Vladimir

2014-09-01

We analyze the correlation and spectral properties of two-photon states resonantly transmitted by a nonlinear optical microcavity. We trace the correlation properties of transmitted two-photon states to the decay spectrum of multiphoton resonances in the nonlinear microcavity.

Effects of biasing on the galaxy power spectrum at large scales

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beltran Jimenez, Jose; Departamento de Fisica Teorica, Universidad Complutense de Madrid, 28040, Madrid; Durrer, Ruth

2011-05-15

In this paper we study the effect of biasing on the power spectrum at large scales. We show that even though nonlinear biasing does introduce a white noise contribution on large scales, the P(k){proportional_to}k{sup n} behavior of the matter power spectrum on large scales may still be visible and above the white noise for about one decade. We show, that the Kaiser biasing scheme which leads to linear bias of the correlation function on large scales, also generates a linear bias of the power spectrum on rather small scales. This is a consequence of the divergence on small scales ofmore » the pure Harrison-Zeldovich spectrum. However, biasing becomes k dependent if we damp the underlying power spectrum on small scales. We also discuss the effect of biasing on the baryon acoustic oscillations.« less

Fluorescence spectroscopy for endogenous porphyrins in human facial skin

NASA Astrophysics Data System (ADS)

Seo, I.; Tseng, S. H.; Cula, G. O.; Bargo, P. R.; Kollias, N.

2009-02-01

The activity of certain bacteria in skin is known to correlate to the presence of porphyrins. In particular the presence of coproporphyrin produced by P.acnes inside plugged pores has been correlated to acne vulgaris. Another porphyrin encountered in skin is protoporphyrin IX, which is produced by the body in the pathway for production of heme. In the present work, a fluorescence spectroscopy system was developed to measure the characteristic spectrum and quantify the two types of porphyrins commonly present in human facial skin. The system is comprised of a Xe lamp both for fluorescence excitation and broadband light source for diffuse reflectance measurements. A computer-controlled filter wheel enables acquisition of sequential spectra, first excited by blue light at 405 nm then followed by the broadband light source, at the same location. The diffuse reflectance spectrum was used to correct the fluorescence spectrum due to the presence of skin chromophores, such as blood and melanin. The resulting fluorescence spectra were employed for the quantification of porphyrin concentration in a population of healthy subjects. The results show great variability on the concentration of these porphyrins and further studies are being conducted to correlate them with skin conditions such as inflammation and acne vulgaris.