Statistical properties for thevibrational energy levels of OCS
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
A potential energy surface for the electronic ground state of carbonyl sulfide was optimized by using a self-consistent configuration-interaction method and involving the recently observed vibrational band origins up to 8000 cm?1. With the optimized potential, the vibrational energy levels of OCS up to 15000 cm?1 were computed using the discrete variable representation method and Lanczos algorithm. Approximately 480 vibrational energy levels were identified. The statistical investigation showed that the vibrational energy levels of OCS up to 15000 cm?1 are largely regular.
Statistical properties of levels and lines in complex spectra
Pain, Jean-Christophe
2016-01-01
We review recent developments of the statistical properties of complex atomic spectra, based on the pioneering work of Claire Bauche-Arnoult and Jacques Bauche. We discuss several improvements of the statistical methods (UTA, SOSA) for the modeling of the lines in a transition array: impact of high-order moments, choice of the distribution (Generalized Gaussian, Normal Inverse Gaussian) and corrections at low temperatures. The second part of the paper concerns general properties of transition arrays, such as propensity rule and generalized J-file sum rule (for E1 or E2 lines), emphasizing the particular role of the G1 exchange Slater integral. The statistical modeling introduced by J. Bauche and C. Bauche-Arnoult for the distribution of the M values (projection of total angular momentum J) in an electron configuration, written P(M), was extended in order to account for configurations with a high-l spectator and a new analytical formula for the evaluation of the number of E1 lines with a wider range of applica...
Energy Technology Data Exchange (ETDEWEB)
Lombardi, M.; Seligman, T.H. (Laboratoire de Spectrometrie Physique-Universite Joseph Fourier de Grenoble, Boite Postale No. 87, 38402 Saint Martin d' Heres, CEDEX (France))
1993-05-01
We study Rydberg molecules taking into account the interaction between the rotational motion of the nuclei and the radial motion of the electron. This situation can be treated to a good approximation in quantum mechanics by the multichannel quantum-defect method which in turn has a well-defined classical limit. We are able to calculate very long sequences of levels and the corresponding amplitudes of wave packets. This allows us to study the statistical properties of both in detail. Our interest focuses on aspects of quantum chaos'' that can be particularly well understood in this case. Our main result is that, in a completely chaotic classical situation, where statistics of quantum-level spacings follow the expected universal Gaussian-orthogonal-ensemble behavior, and statistics of line intensities display the expected universal Porter-Thomas behavior, nonuniversal properties are explicitly contained in correlations between intensities and spacings, determined by the time needed for the classical system to mix on a length scale given by the quantum wavelength.
Approximating Stationary Statistical Properties
Institute of Scientific and Technical Information of China (English)
Xiaoming WANG
2009-01-01
It is well-known that physical laws for large chaotic dynamical systems are revealed statistically. Many times these statistical properties of the system must be approximated numerically. The main contribution of this manuscript is to provide simple and natural criterions on numerical methods (temporal and spatial discretization) that are able to capture the stationary statistical properties of the underlying dissipative chaotic dynamical systems asymptotically. The result on temporal approximation is a recent finding of the author, and the result on spatial approximation is a new one. Applications to the infinite Prandtl number model for convection and the barotropic quasi-geostrophic model are also discussed.
Integrable matrix theory: Level statistics.
Scaramazza, Jasen A; Shastry, B Sriram; Yuzbashyan, Emil A
2016-09-01
We study level statistics in ensembles of integrable N×N matrices linear in a real parameter x. The matrix H(x) is considered integrable if it has a prescribed number n>1 of linearly independent commuting partners H^{i}(x) (integrals of motion) [H(x),H^{i}(x)]=0, [H^{i}(x),H^{j}(x)]=0, for all x. In a recent work [Phys. Rev. E 93, 052114 (2016)2470-004510.1103/PhysRevE.93.052114], we developed a basis-independent construction of H(x) for any n from which we derived the probability density function, thereby determining how to choose a typical integrable matrix from the ensemble. Here, we find that typical integrable matrices have Poisson statistics in the N→∞ limit provided n scales at least as logN; otherwise, they exhibit level repulsion. Exceptions to the Poisson case occur at isolated coupling values x=x_{0} or when correlations are introduced between typically independent matrix parameters. However, level statistics cross over to Poisson at O(N^{-0.5}) deviations from these exceptions, indicating that non-Poissonian statistics characterize only subsets of measure zero in the parameter space. Furthermore, we present strong numerical evidence that ensembles of integrable matrices are stationary and ergodic with respect to nearest-neighbor level statistics.
Integrable matrix theory: Level statistics
Scaramazza, Jasen A.; Shastry, B. Sriram; Yuzbashyan, Emil A.
2016-09-01
We study level statistics in ensembles of integrable N ×N matrices linear in a real parameter x . The matrix H (x ) is considered integrable if it has a prescribed number n >1 of linearly independent commuting partners Hi(x ) (integrals of motion) "]Hi(x ) ,Hj(x ) ]">H (x ) ,Hi(x ) =0 , for all x . In a recent work [Phys. Rev. E 93, 052114 (2016), 10.1103/PhysRevE.93.052114], we developed a basis-independent construction of H (x ) for any n from which we derived the probability density function, thereby determining how to choose a typical integrable matrix from the ensemble. Here, we find that typical integrable matrices have Poisson statistics in the N →∞ limit provided n scales at least as logN ; otherwise, they exhibit level repulsion. Exceptions to the Poisson case occur at isolated coupling values x =x0 or when correlations are introduced between typically independent matrix parameters. However, level statistics cross over to Poisson at O (N-0.5) deviations from these exceptions, indicating that non-Poissonian statistics characterize only subsets of measure zero in the parameter space. Furthermore, we present strong numerical evidence that ensembles of integrable matrices are stationary and ergodic with respect to nearest-neighbor level statistics.
Li, J.; Gray, B.R.; Bates, D.M.
2008-01-01
Partitioning the variance of a response by design levels is challenging for binomial and other discrete outcomes. Goldstein (2003) proposed four definitions for variance partitioning coefficients (VPC) under a two-level logistic regression model. In this study, we explicitly derived formulae for multi-level logistic regression model and subsequently studied the distributional properties of the calculated VPCs. Using simulations and a vegetation dataset, we demonstrated associations between different VPC definitions, the importance of methods for estimating VPCs (by comparing VPC obtained using Laplace and penalized quasilikehood methods), and bivariate dependence between VPCs calculated at different levels. Such an empirical study lends an immediate support to wider applications of VPC in scientific data analysis.
Integrable matrix theory: Level statistics
2016-01-01
We study level statistics in ensembles of integrable $N\\times N$ matrices linear in a real parameter $x$. The matrix $H(x)$ is considered integrable if it has a prescribed number $n>1$ of linearly independent commuting partners $H^i(x)$ (integrals of motion) $\\left[H(x),H^i(x)\\right] = 0$, $\\left[H^i(x), H^j(x)\\right]$ = 0, for all $x$. In a recent work, we developed a basis-independent construction of $H(x)$ for any $n$ from which we derived the probability density function, thereby determin...
Statistical properties of earthquakes clustering
Directory of Open Access Journals (Sweden)
A. Vecchio
2008-04-01
Full Text Available Often in nature the temporal distribution of inhomogeneous stochastic point processes can be modeled as a realization of renewal Poisson processes with a variable rate. Here we investigate one of the classical examples, namely, the temporal distribution of earthquakes. We show that this process strongly departs from a Poisson statistics for both catalogue and sequence data sets. This indicate the presence of correlations in the system probably related to the stressing perturbation characterizing the seismicity in the area under analysis. As shown by this analysis, the catalogues, at variance with sequences, show common statistical properties.
Statistical properties of convex clustering
Tan, Kean Ming; Witten, Daniela
2015-01-01
In this manuscript, we study the statistical properties of convex clustering. We establish that convex clustering is closely related to single linkage hierarchical clustering and $k$-means clustering. In addition, we derive the range of the tuning parameter for convex clustering that yields a non-trivial solution. We also provide an unbiased estimator of the degrees of freedom, and provide a finite sample bound for the prediction error for convex clustering. We compare convex clustering to so...
Statistical Properties of Neural Networks
Shinomoto, S.
1986-06-01
Some characteristics of a large population of heterogeneously connected neurons are investigated by a model system composed of McCulloch-Pitts elements. Gross properties are controlled by a few statistical parameters and they show bifurcations. In a synchronous processing algorithm, we find distinct regimes where the system is either monostable, bistable, periodic, or chaotic. In the cyclic processing algorithm which is a kind of asynchronous one, the last two regimes are fussed into a multibasin regime where the system possesses a number of basins of fixed points and chaotic orbits. The number of fixed points is estimated in some regions.
Statistical properties of Chinese semantic networks
Institute of Scientific and Technical Information of China (English)
LIU HaiTao
2009-01-01
Almost all language networks in word and syntactic levels are small-world and scale-free.This raises the questions of whether a language network in deeper semantic or cognitive level also has the similar properties.To answer the question,we built up a Chinese semantic network based on a treebank with semantic role (argument structure) annotation and investigated its global statistical properties.The results show that although semantic network is also small-world and scale-free,it is different from syntactic network in hierarchical structure and K-Nearest-Neighbor correlation.
Statistical Properties of Genealogical Trees
Derrida, Bernard; Manrubia, Susanna C.; Zanette, Damián H.
1999-03-01
We analyze the statistical properties of genealogical trees in a neutral model of a closed population with sexual reproduction and nonoverlapping generations. By reconstructing the genealogy of an individual from the population evolution, we measure the distribution of ancestors appearing more than once in a given tree. After a transient time, the probability of repetition follows, up to a rescaling, a stationary distribution which we calculate both numerically and analytically. This distribution exhibits a universal shape with a nontrivial power law which can be understood by an exact, though simple, renormalization calculation. Some real data on human genealogy illustrate the problem, which is relevant to the study of the real degree of diversity in closed interbreeding communities.
Bressan, L.; Tinti, S.
2016-01-01
This study presents a new method to analyse the properties of the sea-level signal recorded by coastal tide gauges in the long wave range that is in a window between wind/storm waves and tides and is typical of several phenomena like local seiches, coastal shelf resonances and tsunamis. The method consists of computing four specific functions based on the time gradient (slope) of the recorded sea level oscillations, namely the instantaneous slope (IS) as well as three more functions based on IS, namely the reconstructed sea level (RSL), the background slope (BS) and the control function (CF). These functions are examined through a traditional spectral fast Fourier transform (FFT) analysis and also through a statistical analysis, showing that they can be characterised by probability distribution functions PDFs such as the Student's t distribution (IS and RSL) and the beta distribution (CF). As an example, the method has been applied to data from the tide-gauge station of Siracusa, Italy.
Properties of Rasch residual fit statistics.
Wu, Margaret; Adams, Richard J
2013-01-01
This paper examines the residual-based fit statistics commonly used in Rasch measurement. In particular, the paper analytically examines some of the theoretical properties of the residual-based fit statistics with a view to establishing the inferences that can be made using these fit statistics. More specifically, the relationships between the distributional properties of the fit statistics and sample size are discussed; some research that erroneously concludes that residual-based fit statistics are unstable is reviewed; and finally, it is analytically illustrated that, for dichotomous items, residual-based fit statistics provide a measure of the relative slope of empirical item characteristic curves. With a clear understanding of the theoretical properties of the fit statistics, the use and limitations of these statistics can be placed in the right light.
Critical level statistics for weakly disordered graphene.
Amanatidis, E; Kleftogiannis, I; Katsanos, D E; Evangelou, S N
2014-04-16
In two dimensions chaotic level statistics with the Wigner spacing distribution P(S) is expected for massless fermions in the Dirac region. The obtained P(S) for weakly disordered finite graphene samples with zigzag edges turns out, however, to be neither chaotic (Wigner) nor localized (Poisson). It is similar to the intermediate statistics at the critical point of the Anderson metal-insulator transition. The quantum transport of finite graphene for weak disorder, with critical level statistics can occur via edge states as in topological insulators, and for strong disorder, graphene behaves as an ordinary Anderson insulator with Poisson statistics.
Effect of Landau level mixing on braiding statistics.
Simon, Steven H
2008-03-21
We examine the effect of Landau level mixing on the braiding statistics of quasiparticles of Abelian and non-Abelian quantum Hall states. While path dependent geometric phases can perturb the Abelian part of the statistics, we find that the non-Abelian properties remain unchanged to an accuracy that is exponentially small in the distance between quasiparticles.
Intermetallics structures, properties, and statistics
Steurer, Walter
2016-01-01
The focus of this book is clearly on the statistics, topology, and geometry of crystal structures and crystal structure types. This allows one to uncover important structural relationships and to illustrate the relative simplicity of most of the general structural building principles. It also allows one to show that a large variety of actual structures can be related to a rather small number of aristotypes. It is important that this book is readable and beneficial in the one way or another for everyone interested in intermetallic phases, from graduate students to experts in solid-state chemistry/physics/materials science. For that purpose it avoids using an enigmatic abstract terminology for the classification of structures. The focus on the statistical analysis of structures and structure types should be seen as an attempt to draw the background of the big picture of intermetallics, and to point to the white spots in it, which could be worthwhile exploring. This book was not planned as a textbook; rather, it...
Statistical properties of curved polymer
Indian Academy of Sciences (India)
Surya Kanta Ghosh; Anirban Sain
2008-08-01
Intrinsic curvature of biopolymers is emerging as an essential feature in various biological phenomena. Examples of polymers with intrinsic curvature are microtubule in eukaryotic cells or FtsZ filaments in prokaryotic cells. We consider the general model for polymers with intrinsic curvature. We aim to study both equilibrium and dynamic properties of such polymers. Here we report preliminary results on the equilibrium distribution function $P({\\mathbf{R}})$ of the end-to-end distance ${\\mathbf{R}}$. We employ transfer matrix method for this study.
Statistical properties of quantum spectra in nuclei
Institute of Scientific and Technical Information of China (English)
WU; Xizhen
2001-01-01
［1］Wu Xizhen,Sakata,F.,Zhuo Yizhong et al.,Dynamic realization of statistical state in finite systems,Phys.ReV.C,1996,53:1233-1244.［2］Weidenmüller,H.A.,Statistical theory of nuclear reactions and the Gaussian Othogonal Ensemble,Annals of Physics,1984,158:120-141.［3］Hag,R.U.,Pandey,A.,Bohigas,O.,Fluctuation properties of nuclear energy levels:Do theory and experiment agree? Phys.Rev.Lett.,1982,48:1086-1089.［4］Wu Xizhen,Gu Jianzhong,Iwamoto,A.,Statistical properties of quasiparticle spectra in deformed nuclei,Phys.Rev.C,1999,59:215-220.［5］Garrett,J.D.,Robinson,J.Q.,Foglia,A.J.et al.,Nuclear level repulsion and order vs chaos,Phys.Lett.B,1997,392:24-29.［6］Bohigas,O.,Hag,R.U.,Pandy,A.,Fluctuation properties of nuclear energy levels and widths comparison of theory with experiment,in Nuclear Data for Science and Technology (ed.Bockhoff,K.H.),Dordrecht:Reidel,1983,809-813.［7］Heiss,W.D.,Nazmitdinov,R.G.,Radu,S.,Chaos in axially symmetric potentials with Octupole deformation,Phys.Rev.Lett.,1994,72:2351-2354.［8］Wu Xizhen,Gu Jianzhong,Zhuo Yizhong et al.,Possible understanding of hyperdeformed 144-146Ba nuclei appearing in the spontaneous fission of 252Cf,Phys.Rev.Lett.,1997,79:4542-4545.［9］Ter-Akopian,G.M.,Hamilton,J.H.,Oganessian,Y.T.et al.,New spontaneous fission mode for 252Cf:Indication of hyperdeformed 144,145,146Ba at scission,Phys.Rev.Lett.,1996,77:32-35.［10］Adamian,G.G.,Antonenko,N.V.,Ivanova,S.P.et al.,Problems in description of fusion of heavy nuclei in the two-center shell model approach,Nucl.Phys.A,1999,646:29-52.［11］Hofmann,H.,A quantal transport theory for nuclear collective motion:the metrits of a locally harmonic approximation method,Phys.Rep.,1997,284:139-380.［12］Gu Jianzhong,Wu Xizhen,Zhuo Yizhong,Quantum chaotic motion of a single particle in heavy nuclei,Nucl.Phys.A,1997,625:621-632.［13］Gu Jianzhong,Wu Xizhen,Zhuo Yizhong,The single-particle spectrum and its spacing and curvature distributions in
Energy level statistics of quantum dots.
Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Woods Halley, J
2007-05-08
We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.
Energy level statistics of quantum dots
Energy Technology Data Exchange (ETDEWEB)
Tsau, C-Y [University of Wisconsin-Madison, Madison, WI 53706 (United States); Nghiem, Diu [University of Wisconsin-Madison, Madison, WI 53706 (United States); Joynt, Robert [University of Wisconsin-Madison, Madison, WI 53706 (United States); Halley, J Woods [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455 (United States)
2007-05-08
We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.
Energy level statistics of quantum dots
Tsau, Chien-Yu; Nghiem, Diu; Joynt, Robert; Halley, J. Woods
2007-05-01
We investigate the charging energy level statistics of disordered interacting electrons in quantum dots by numerical calculations using the Hartree approximation. The aim is to obtain a global picture of the statistics as a function of disorder and interaction strengths. We find Poisson statistics at very strong disorder, Wigner-Dyson statistics for weak disorder and interactions, and a Gaussian intermediate regime. These regimes are as expected from previous studies and fundamental considerations, but we also find interesting and rather broad crossover regimes. In particular, intermediate between the Gaussian and Poisson regimes we find a two-sided exponential distribution for the energy level spacings. In comparing with experiment, we find that this distribution may be realized in some quantum dots.
Microwave Enhancement in Coronal Holes: Statistical Properties
Indian Academy of Sciences (India)
Ν. Gopalswamy; Κ. Shibasaki; Μ. Salem
2000-09-01
We report on the statistical properties of the microwave enhancement (brightness temperature, area, fine structure, life time and magnetic field strength) in coronal holes observed over a period of several solar rotations.
Directory of Open Access Journals (Sweden)
L. Bressan
2016-01-01
reconstructed sea level (RSL, the background slope (BS and the control function (CF. These functions are examined through a traditional spectral fast Fourier transform (FFT analysis and also through a statistical analysis, showing that they can be characterised by probability distribution functions PDFs such as the Student's t distribution (IS and RSL and the beta distribution (CF. As an example, the method has been applied to data from the tide-gauge station of Siracusa, Italy.
Statistics of high-level scene context.
Greene, Michelle R
2013-01-01
CONTEXT IS CRITICAL FOR RECOGNIZING ENVIRONMENTS AND FOR SEARCHING FOR OBJECTS WITHIN THEM: contextual associations have been shown to modulate reaction time and object recognition accuracy, as well as influence the distribution of eye movements and patterns of brain activations. However, we have not yet systematically quantified the relationships between objects and their scene environments. Here I seek to fill this gap by providing descriptive statistics of object-scene relationships. A total of 48, 167 objects were hand-labeled in 3499 scenes using the LabelMe tool (Russell et al., 2008). From these data, I computed a variety of descriptive statistics at three different levels of analysis: the ensemble statistics that describe the density and spatial distribution of unnamed "things" in the scene; the bag of words level where scenes are described by the list of objects contained within them; and the structural level where the spatial distribution and relationships between the objects are measured. The utility of each level of description for scene categorization was assessed through the use of linear classifiers, and the plausibility of each level for modeling human scene categorization is discussed. Of the three levels, ensemble statistics were found to be the most informative (per feature), and also best explained human patterns of categorization errors. Although a bag of words classifier had similar performance to human observers, it had a markedly different pattern of errors. However, certain objects are more useful than others, and ceiling classification performance could be achieved using only the 64 most informative objects. As object location tends not to vary as a function of category, structural information provided little additional information. Additionally, these data provide valuable information on natural scene redundancy that can be exploited for machine vision, and can help the visual cognition community to design experiments guided by statistics
Statistics of High-level Scene Context
Directory of Open Access Journals (Sweden)
Michelle R. Greene
2013-10-01
Full Text Available Context is critical to our ability to recognize environments and to search for objects within them: contextual associations have been shown to modulate reaction time and object recognition accuracy, as well as influence the distribution of eye movements and patterns of brain activations. However, we have not yet systematically quantified the relationships between objects and their scene environments. Here I seek to fill this gap by providing descriptive statistics of object-scene relationships. A total of 48,167 objects were hand-labeled in 3499 scenes using the LabelMe tool (Russell, Torralba, Muphy & Freeman, 2008. From these data, I computed a variety of descriptive statistics at three different levels of analysis: the ensemble statistics that describe the density and spatial distribution of unnamed things in the scene; the bag of words level where scenes are described by the list of objects contained within them; and the structural level where the spatial distribution and relationships between the objects are measured. The utility of each level of description for scene categorization was assessed through the use of linear classifiers, and the plausibility of each level for modeling human rapid scene categorization is discussed. Ensemble statistics were found to be the most informative (per feature, and also best explained human patterns of categorization errors. Although a bag of words classifier had similar performance to human observers, it had a markedly different pattern of errors. Some objects are more useful than others, and ceiling classification performance could be achieved using only the 64 most informative objects. As object location tends not to vary as a function of category, structural information provided little additional information. Additionally, these data provide valuable information on natural scene redundancy that can be exploited for machine vision, and can help researchers in visual cognition design new data
Statistical properties of transport in plasma turbulence
DEFF Research Database (Denmark)
Naulin, V.; Garcia, O.E.; Nielsen, A.H.;
2004-01-01
The statistical properties of the particle flux in different types of plasma turbulence models are numerically investigated using probability distribution functions (PDFs). The physics included in the models range from two-dimensional drift wave turbulence to three-dimensional MHD dynamics...
Level density of a bose gas and extreme value statistics.
Comtet, A; Leboeuf, P; Majumdar, Satya N
2007-02-16
We establish a connection between the level density of a gas of noninteracting bosons and the theory of extreme value statistics. Depending on the exponent that characterizes the growth of the underlying single-particle spectrum, we show that at a given excitation energy the limiting distribution function for the number of excited particles follows the three universal distribution laws of extreme value statistics, namely, the Gumbel, Weibull, and Fréchet distributions. Implications of this result, as well as general properties of the level density at different energies, are discussed.
Statistical properties of extragalactic radio sources
Institute of Scientific and Technical Information of China (English)
Zhang Jiang-Shui
2004-01-01
In this paper, a large sample of extragalactic radio sources is analysed to show their statistical properties. The core and total radio powers are used to determine the core-dominance parameter for galaxies, BL Lacertae objects and quasars; mutual correlations between core radio power, total radio power, redshift and core dominance parameter are 0examined for different subclasses. A statistically significant correlation between the total and core radio power is confirmed. There are no obvious correlations between core-dominance parameter and the total power for our whole sample and quasars, but there is a statistically significant anti-correlation for our galaxy sample. Some discussions and comparison of the correlations with those obtained by other authors are also given.
Statistical properties of superimposed stationary spike trains.
Deger, Moritz; Helias, Moritz; Boucsein, Clemens; Rotter, Stefan
2012-06-01
The Poisson process is an often employed model for the activity of neuronal populations. It is known, though, that superpositions of realistic, non- Poisson spike trains are not in general Poisson processes, not even for large numbers of superimposed processes. Here we construct superimposed spike trains from intracellular in vivo recordings from rat neocortex neurons and compare their statistics to specific point process models. The constructed superimposed spike trains reveal strong deviations from the Poisson model. We find that superpositions of model spike trains that take the effective refractoriness of the neurons into account yield a much better description. A minimal model of this kind is the Poisson process with dead-time (PPD). For this process, and for superpositions thereof, we obtain analytical expressions for some second-order statistical quantities-like the count variability, inter-spike interval (ISI) variability and ISI correlations-and demonstrate the match with the in vivo data. We conclude that effective refractoriness is the key property that shapes the statistical properties of the superposition spike trains. We present new, efficient algorithms to generate superpositions of PPDs and of gamma processes that can be used to provide more realistic background input in simulations of networks of spiking neurons. Using these generators, we show in simulations that neurons which receive superimposed spike trains as input are highly sensitive for the statistical effects induced by neuronal refractoriness.
Low-Level Hierarchical Multiscale Segmentation Statistics of Natural Images.
Akbas, Emre; Ahuja, Narendra
2014-09-01
This paper is aimed at obtaining the statistics as a probabilistic model pertaining to the geometric, topological and photometric structure of natural images. The image structure is represented by its segmentation graph derived from the low-level hierarchical multiscale image segmentation. We first estimate the statistics of a number of segmentation graph properties from a large number of images. Our estimates confirm some findings reported in the past work, as well as provide some new ones. We then obtain a Markov random field based model of the segmentation graph which subsumes the observed statistics. To demonstrate the value of the model and the statistics, we show how its use as a prior impacts three applications: image classification, semantic image segmentation and object detection.
Characterization through distributional properties of dual generalized order statistics
Directory of Open Access Journals (Sweden)
A.H. Khan
2012-10-01
Full Text Available Distributional properties of two non-adjacent dual generalized order statistics have been used to characterize distributions. Further, one sided contraction and dilation for the dual generalized order statistics are discussed and then the results are deduced for generalized order statistics, order statistics, lower record statistics, upper record statistics and adjacent dual generalized order statistics.
Statistical properties of random density matrices
Sommers, H J; Sommers, Hans-Juergen; Zyczkowski, Karol
2004-01-01
Statistical properties of ensembles of random density matrices are investigated. We compute traces and von Neumann entropies averaged over ensembles of random density matrices distributed according to the Bures measure. The eigenvalues of the random density matrices are analyzed: we derive the eigenvalue distribution for the Bures ensemble which is shown to be broader then the quarter--circle distribution characteristic of the Hilbert--Schmidt ensemble. For measures induced by partial tracing over the environment we compute exactly the two-point eigenvalue correlation function.
Statistical properties of random density matrices
Energy Technology Data Exchange (ETDEWEB)
Sommers, Hans-Juergen [Fachbereich Physik, Universitaet Duisburg-Essen, Campus Essen, 45117 Essen (Germany); Zyczkowski, Karol [Instytut Fizyki im. Smoluchowskiego, Uniwersytet Jagiellonski, ul. Reymonta 4, 30-059 Cracow (Poland)
2004-09-03
Statistical properties of ensembles of random density matrices are investigated. We compute traces and von Neumann entropies averaged over ensembles of random density matrices distributed according to the Bures measure. The eigenvalues of the random density matrices are analysed: we derive the eigenvalue distribution for the Bures ensemble which is shown to be broader then the quarter-circle distribution characteristic of the Hilbert-Schmidt ensemble. For measures induced by partial tracing over the environment we compute exactly the two-point eigenvalue correlation function.
Statistical properties of ionospheric stimulated electromagnetic emissions
Directory of Open Access Journals (Sweden)
R. L. Karlsson
2006-08-01
Full Text Available We have analysed the statistical properties of the stimulated electromagnetic emissions (SEE spectral features in the steady state, reached after a long period of continuous HF pumping of the ionosphere in experiments performed at the Sura ionospheric radio research facility in Russia. Using a digital filter bank method, we have been able to analyse complex valued signals within narrow frequency bands. Each of the SEE spectral features are thereby separated into a number of narrow spectral components. Statistical tests were performed for all these spectral components and the distributions of the spectral amplitudes and phases were evaluated. Also, a test for sinusoidal components was performed. These tests showed that all observed SEE features were indistinguishable from coloured Gaussian noise. The test results exclude that the SEE features can be the result of a single isolated coherent process, but does not rule out that there could be many statistically independent parametric wave-wave processes taking place simultaneously at various parts of the HF-pumped ionosphere, as long as the superposition from all these is incoherent. Furthermore, from the test results, we cannot exclude the possibility that the waveforms of some, or all, of the SEE features may be chaotic.
Rapid neural adaptation to sound level statistics.
Dean, Isabel; Robinson, Ben L; Harper, Nicol S; McAlpine, David
2008-06-18
Auditory neurons must represent accurately a wide range of sound levels using firing rates that vary over a far narrower range of levels. Recently, we demonstrated that this "dynamic range problem" is lessened by neural adaptation, whereby neurons adjust their input-output functions for sound level according to the prevailing distribution of levels. These adjustments in input-output functions increase the accuracy with which levels around those occurring most commonly are coded by the neural population. Here, we examine how quickly this adaptation occurs. We recorded from single neurons in the auditory midbrain during a stimulus that switched repeatedly between two distributions of sound levels differing in mean level. The high-resolution analysis afforded by this stimulus showed that a prominent component of the adaptation occurs rapidly, with an average time constant across neurons of 160 ms after an increase in mean level, much faster than our previous experiments were able to assess. This time course appears to be independent of both the timescale over which sound levels varied and that over which sound level distributions varied, but is related to neural characteristic frequency. We find that adaptation to an increase in mean level occurs more rapidly than to a decrease. Finally, we observe an additional, slow adaptation in some neurons, which occurs over a timescale of tens of seconds. Our findings provide constraints in the search for mechanisms underlying adaptation to sound level. They also have functional implications for the role of adaptation in the representation of natural sounds.
Level statistics for nearly integrable systems.
Abul-Magd, A Y
2009-07-01
We assume that the level spectra of quantum systems in the initial phase of transition from integrability to chaos are approximated by superpositions of independent sequences. Each individual sequence is modeled by a random matrix ensemble. We obtain analytical expressions for the level spacing distribution and level number variance for such a system. These expressions are successfully applied to the analysis of the resonance spectrum in a nearly integrable microwave billiard.
The Statistical Properties of Galaxies Containing ULXs
Ptak, A
2004-01-01
We present a statistical analysis of the properties of galaxies containing ultraluminous X-ray objects (ULXs). Our primary goal is to establish the fraction of galaxies containing a ULX as a function of ULX luminosity. Our sample is based on ROSAT HRI observations of galaxies. We find that ~ 12% of galaxies contain at least one ULX with L_X > 10^39 erg/s and ~ 1% of galaxies contain at least one ULX with L_X > 10^40 erg/s. These ULX frequencies are lower limits since ROSAT HRI observation would miss absorbed ULXs (i.e., with N_H >~ 10^21 cm^-2) and those within ~ 10" of the nucleus (due to the positional error circle of the ROSAT HRI). The Hubble type distribution of galaxies with a ULX differs significantly from the distribution of types for nearby RC3 galaxies, but does not differ significantly from the galaxy type distribution of galaxies observed by the HRI in general. We find no increase in the mean FIR luminosity or FIR / K band luminosity ratio for galaxies with a ULX relative to galaxies observed by t...
The use of statistical techniques in par-level management.
Klee, W B
1994-02-01
The total quality management movement has allowed the reintroduction of statistics in the materials management workplace. Statistical methods can be applied to the par level management process with significant results.
Statistical Properties of the E(5) and X(5) Symmetries
Shu, J; Liu, Y X; Shu, Jing; Jia, Hong-Bo; Liu, Yu-Xin
2002-01-01
We study the energy level statistics of the states in E(5) and X(5) transitional dynamical symmetries. The calculated results indicate that the statistics of E(5) symmetry is regular and follows Poisson statistics, while the statistics of X(5) symmetry involves two maxima in the nearest neighbor level spacing distribution $P(s)$ and the $\\Delta_{3}$ statistics follows the GOE statistics. It provides an evidence that the X(5) symmetry is at the critical point exhibiting competing degree of freedom.
Relativistic quantum level-spacing statistics in chaotic graphene billiards.
Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2010-05-01
An outstanding problem in quantum nonlinear dynamics concerns about the energy-level statistics in experimentally accessible relativistic quantum systems. We demonstrate, using chaotic graphene confinements where electronic motions are governed by the Dirac equation in the low-energy regime, that the level-spacing statistics are those given by Gaussian orthogonal ensemble (GOE) random matrices. Weak magnetic field can change the level-spacing statistics to those of Gaussian unitary ensemble for electrons in graphene. For sufficiently strong magnetic field, the GOE statistics are restored due to the appearance of Landau levels.
Statistical properties of successive ocean wave parameters
Energy Technology Data Exchange (ETDEWEB)
Wist, Hanne Therese
2004-07-01
For random waves the free surface elevation can be described by a number of individual wave parameters. The main object of this work has been to study the statistical properties of individual parameters in successive waves; the wave crest height, the wave height and the wave period. In severe sea states the wave crest heights exhibit a nonlinear behavior, which must be reflected in the models. An existing marginal distribution that uses second order Stokes-type nonlinearity is transformed to a two-dimensional distribution by use of the two-dimensional Rayleigh distribution. This model only includes sum frequency effects. A two-dimensional distribution is also established by transforming a second order model including both sum and difference frequency effects. Both models are based on the narrow-band assumption, and the effect of finite water depth is included. A parametric wave crest height distribution proposed by Forristall (2000) has been extended to two dimensions by transformation of the two-dimensional Weibull distribution. Two successive wave heights are modeled by a Gaussian copula, which is referred to as the Nataf model. Results with two initial distributions for the transformation are presented, the Naess (1985) model and a two-parameter Weibull distribution, where the latter is in best agreement with data. The results are compared with existing models. The Nataf model has also been used for modeling three successive wave heights. Results show that the Nataf transformation of three successive wave heights can be approximated by a first order autoregressive model. This means that the distribution of the wave height given the previous wave height is independent of the wave heights prior to the previous wave height. The simulation of successive wave heights can be done directly without simulating the time series of the complete surface elevation. Successive wave periods are modeled with the Nataf transformation by using a two-parameter Weibull distribution
Beauty in abstract paintings: perceptual contrast and statistical properties
Mallon, Birgit; Redies, Christoph; Hayn-Leichsenring, Gregor U.
2014-01-01
In this study, we combined the behavioral and objective approach in the field of empirical aesthetics. First, we studied the perception of beauty by investigating shifts in evaluation on perceived beauty of abstract artworks (Experiment 1). Because the participants showed heterogeneous individual preferences for the paintings, we divided them into seven clusters for the test. The experiment revealed a clear pattern of perceptual contrast. The perceived beauty of abstract paintings increased after exposure to paintings that were rated as less beautiful, and it decreased after exposure to paintings that were rated as more beautiful. Next, we searched for correlations of beauty ratings and perceptual contrast with statistical properties of abstract artworks (Experiment 2). The participants showed significant preferences for particular image properties. These preferences differed between the clusters of participants. Strikingly, next to color measures like hue, saturation, value and lightness, the recently described Pyramid of Histograms of Orientation Gradients (PHOG) self-similarity value seems to be a predictor for aesthetic appreciation of abstract artworks. We speculate that the shift in evaluation in Experiment 1 was, at least in part, based on low-level adaptation to some of the statistical image properties analyzed in Experiment 2. In conclusion, our findings demonstrate that the perception of beauty in abstract artworks is altered after exposure to beautiful or non-beautiful images and correlates with particular image properties, especially color measures and self-similarity. PMID:24711791
Beauty in abstract paintings: Perceptual contrast and statistical properties
Directory of Open Access Journals (Sweden)
Birgit eMallon
2014-03-01
Full Text Available In this study, we combined the behavioral and objective approach in the field of empirical aesthetics. First, we studied the perception of beauty by investigating shifts in evaluation on perceived beauty of abstract artworks (Experiment 1. Because the participants showed heterogeneous individual preferences for the paintings, we divided them into seven clusters for the test. The experiment revealed a clear pattern of perceptual contrast. The perceived beauty of abstract paintings increased after exposure to paintings that were rated as less beautiful, and it decreased after exposure to paintings that were rated as more beautiful. Next, we searched for correlations of beauty ratings and perceptual contrast with statistical properties of abstract artworks (Experiment 2. The participants showed significant preferences for certain image properties. These preferences differed between the clusters of participants. Strikingly, next to color measures like hue, saturation, value and lightness, the recently described PHOG self-similarity value seems to be a predictor for aesthetic appreciation of abstract artworks. We speculate that the shift in evaluation in Experiment 1 was, at least in part, based on low-level adaptation to some of the statistical image properties analyzed in Experiment 2. In conclusion, our findings demonstrate that the perception of beauty in abstract artworks is altered after exposure to beautiful or non-beautiful images and correlates with particular image properties, especially color measures and self-similarity.
Beauty in abstract paintings: perceptual contrast and statistical properties.
Mallon, Birgit; Redies, Christoph; Hayn-Leichsenring, Gregor U
2014-01-01
In this study, we combined the behavioral and objective approach in the field of empirical aesthetics. First, we studied the perception of beauty by investigating shifts in evaluation on perceived beauty of abstract artworks (Experiment 1). Because the participants showed heterogeneous individual preferences for the paintings, we divided them into seven clusters for the test. The experiment revealed a clear pattern of perceptual contrast. The perceived beauty of abstract paintings increased after exposure to paintings that were rated as less beautiful, and it decreased after exposure to paintings that were rated as more beautiful. Next, we searched for correlations of beauty ratings and perceptual contrast with statistical properties of abstract artworks (Experiment 2). The participants showed significant preferences for particular image properties. These preferences differed between the clusters of participants. Strikingly, next to color measures like hue, saturation, value and lightness, the recently described Pyramid of Histograms of Orientation Gradients (PHOG) self-similarity value seems to be a predictor for aesthetic appreciation of abstract artworks. We speculate that the shift in evaluation in Experiment 1 was, at least in part, based on low-level adaptation to some of the statistical image properties analyzed in Experiment 2. In conclusion, our findings demonstrate that the perception of beauty in abstract artworks is altered after exposure to beautiful or non-beautiful images and correlates with particular image properties, especially color measures and self-similarity.
Selecting Level-Specific Specialized Vocabulary Using Statistical Measures
Chujo, Kiyomi; Utiyama, Masao
2006-01-01
To find an easy-to-use, automated tool to identify technical vocabulary applicable to learners at various levels, nine statistical measures were applied to the 7.3-million-word "commerce and finance" component of the British National Corpus. The resulting word lists showed that each statistical measure extracted a different level of specialized…
Statistical Properties of Turbulence: An Overview
Pandit, Rahul; Ray, Samriddhi Sankar
2009-01-01
We present an introductory overview of several challenging problems in the statistical characterisation of turbulence. We provide examples from fluid turbulence in three and two dimensions, from the turbulent advection of passive scalars, turbulence in the one-dimensional Burgers equation, and fluid turbulence in the presence of polymer additives.
Statistical properties of turbulence: An overview
Indian Academy of Sciences (India)
Rahul Pandit; Prasad Perlekar; Samriddhi Sankar Ray
2009-07-01
We present an introductory overview of several challenging problems in the statistical characterization of turbulence. We provide examples from fluid turbulence in three and two dimensions, from the turbulent advection of passive scalars, turbulence in the one-dimensional Burgers equation, and fluid turbulence in the presence of polymer additives.
Statistical properties of several models of fractional random point processes
Bendjaballah, C.
2011-08-01
Statistical properties of several models of fractional random point processes have been analyzed from the counting and time interval statistics points of view. Based on the criterion of the reduced variance, it is seen that such processes exhibit nonclassical properties. The conditions for these processes to be treated as conditional Poisson processes are examined. Numerical simulations illustrate part of the theoretical calculations.
Statistical Properties of Quantum Spectra in Nuclei
Institute of Scientific and Technical Information of China (English)
2001-01-01
Some aspects of quantum chaos in a finite system have been studied based on the analysis of statistical behaviors of quantum spectrum in nuclei. The experiment data show the transition from order to chaos with increasing excitation energy in spherical nuclei. The dependence of the order to chaos transition on nuclear deformation and nuclear rotating is described. The influence of pairing effect on the order to chaos transition is also discussed. Some important experiment phenomena in nuclear
Statistical scaling properties of planetary topographic fields
Landais, François; Schmidt, Frederic; Lovejoy, Shaun
2016-10-01
The massive acquisition of altimetric data in the solar system has motivated numerous analysis of the topography of planets, in particular the surface roughness. Many statistical indicators have been proposed and widely explored in order to study the surface of plantets. Useful informations have been obtained by the use of those indicators but they often have the disadvantage of been defined at a given scale. By construction, they do not directly take into account the well-established scale symmetry that generally occurs in the case of natural surfaces. Indeed, topography can not be interpreted as a stationary field, meaning that statistical parameters like the mean or the standard deviation exhibit a dependence toward scales. This subject has been widely studied in the past, parallel to the development of the notion of fractals. It is now well established that topography is often efficiently modelled by fractal simulations. More interestingly, the fractal theory provides a mathematical formalism to describe the scale dependence of statistical parameters toward scales. It turns out that simple power-law relations efficiently approach the variability of planetary surfaces.However, The observed intermittency (spatial dependance of the scaling laws) apparently rejects the idea of a global description of any topographic field at the planetary scale. Still, modern developments in the fractal theory might be able to give full account to the observed variability and intermittency. It is possible to extent the fractal interpretation of topography to a multifractal statistical object requiring an infinite number of fractal dimensions (one for each statistical moment order). In the present study, we analyse the global scaling laws of topography for different body in the solar system in order to test the multifractal formalism. We then compare the fractal and multifractal parameters form a body to the other. We demonstrate that a change of processes governing the global
Statistical properties of quantum spectra in nuclei
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Some aspects of quantum chaos in a finite system have been studied based on the analysis of statistical behavior of quantum spectra in nuclei.The experiment data show the transition from order to chaos with increasing excitation energy in spherical nuclei.The dependence of the order to chaos transition on nuclear deformation and nuclear rotating is described.The influence of pairing effect on the order to chaos transition is also discussed.Some important experiment phenomena in nuclear physics have been understood from the point of view of the interplay between order and chaos.
Comment on Energy Level Statistics in the Mixed Regime
Robnik, M; Robnik, Marko; Prosen, Tomaz
1997-01-01
We comment on the recent paper by Abul-Magd (J.Phys.A: Math.Gen. 29 (1996) 1) concerning the energy level statistics in the mixed regime, i.e. such having the mixed classical dynamics where regular and chaotic regions coexist in the phase space. We point out that his basic assumption on the additive property of the level-repulsion function $r(S)$ (conditional probability density) in the sense of dividing it linearly into the regular and chaotic part in proportion to the classical fractional phase space volumes $\\rho_1$ and $\\rho_2=q$ is not justified, since among other things, it relies on the type of Berry's ergodic assumption, which however is right only in a homogeneous ensemble of ergodic systems, but not in the neighbourhood of an integrable system. Thus his resulting distribution cannot be regarded as a theoretically well founded object. We point out that the semiclassical limiting energy level spacing distribution must be of Berry-Robnik (1984) type, and explain what transitional behaviour of the Brody...
Probability properties and fractal properties of statistically recursive sets
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
In this paper we construct a class of statistically recursive sets K by statistical contraction operators and prove the convergence and the measurability of K. Many important sets are the special cases of K. Then we investigate the statistically self-similar measure (or set). We have found some sufficient conditions to ensure the statistically recursive set to be statistically self-similar. We also investigate the distribution PK-1. The zero-one laws and the support of PK-1 are obtained.Finally the Hausdorff dimension and Hausdorff exact measure function of a class of statistically recursive sets constructed by a collection of i.i.d. statistical contraction operators have been obtained.
Statistical Properties of repeating FRB 121102
Wang, F Y
2016-01-01
Fast radio bursts (FRBs) are millisecond-duration radio signals possibly occurring at cosmological distances. However the physical model of FRBs is mystery, many models have been proposed. Here we study the frequency distributions of peak flux, fluence, duration and waiting time for repeating FRB 121102. The cumulative distributions of peak flux, fluence and duration show power-law forms. The waiting time distribution also shows power-law distribution, and is consistent with a non-stationary Poisson process. We also use the statistical results to test the proposed models for FRBs. Comparing with the model predications, we find that the theoretical models proposed by Dai et al. (2016) and Katz (2016) are favored. These distributions are consistent with the predications from avalanche models of driven systems.
Technology for enhancing statistical reasoning at the school level
Biehler, R.; Ben-Zvi, D.; Bakker, A.|info:eu-repo/dai/nl/272605778; Makar, K.
2013-01-01
The purpose of this chapter is to provide an updated overview of digital technologies relevant to statistics education, and to summarize what is currently known about how these new technologies can support the development of students’ statistical reasoning at the school level. A brief literature
Technology for enhancing statistical reasoning at the school level
Biehler, R.; Ben-Zvi, D.; Bakker, A.; Makar, K.
2013-01-01
The purpose of this chapter is to provide an updated overview of digital technologies relevant to statistics education, and to summarize what is currently known about how these new technologies can support the development of students’ statistical reasoning at the school level. A brief literature rev
Statistical properties of random scattering matrices
Seba, P; Zakrzewski, J A; Seba, Petr; Zyczkowski, Karol; Zakrzewski, Jakub
1996-01-01
We discuss the properties of eigenphases of S--matrices in random models simulating classically chaotic scattering. The energy dependence of the eigenphases is investigated and the corresponding velocity and curvature distributions are obtained both theoretically and numerically. A simple formula describing the velocity distribution (and hence the distribution of the Wigner time delay) is derived, which is capable to explain the algebraic tail of the time delay distribution observed recently in microwave experiments. A dependence of the eigenphases on other external parameters is also discussed. We show that in the semiclassical limit (large number of channels) the curvature distribution of S--matrix eigenphases is the same as that corresponding to the curvature distribution of the underlying Hamiltonian and is given by the generalized Cauchy distribution.
Characterization of Photon Statistical Properties with Normalized Mandel Parameter
Institute of Scientific and Technical Information of China (English)
ZHANG Xin-Zheng; WANG Zhen-Hua; LI Hui; WU Qiang; TANG Bai-Quan; GAO Feng; XU Jing-Jun
2008-01-01
Normalized Mandel Parameter is introduced as a new measurement of photon statistics. Dependences of Mandel parameter Q and corresponding normalized Mandel parameter on photon-counting time interval are experimentally investigated for pseudo-thermal light. We demonstrate that is more appropriate than Q to measure the statistical deviation from Poisson distribution, because presents dearly both the intrinsic statistical properties and measuring effects. The advantages of in charactering nonclassical emissions are also discussed.
Level statistics of a pseudo-Hermitian Dicke model.
Deguchi, Tetsuo; Ghosh, Pijush K; Kudo, Kazue
2009-08-01
A non-Hermitian operator that is related to its adjoint through a similarity transformation is defined as a pseudo-Hermitian operator. We study the level statistics of a pseudo-Hermitian Dicke Hamiltonian that undergoes quantum phase transition (QPT). We find that the level-spacing distribution of this Hamiltonian near the integrable limit is close to Poisson distribution, while it is Wigner distribution for the ranges of the parameters for which the Hamiltonian is nonintegrable. We show that the assertion in the context of the standard Dicke model that QPT is a precursor to a change in the level statistics is not valid in general.
Level statistics for the even-even Yb isotopes
Institute of Scientific and Technical Information of China (English)
CHEN Fang-Qi; SUN Yang; ZHOU Xian-Rong
2009-01-01
The level statistics of the even-even Yb isotopes are studied by using the energy levels calculated by the projected shell model. The spectrum of intrinsic states and band energies are also studied to discuss the generation of chaoticity. The energy dependence of the chaoticity is investigated, and a chaos to order transition is found.
Electron Energy Level Statistics in Graphene Quantum Dots
De Raedt, H.; Katsnellson, M. I.; Katsnelson, M.I.
2008-01-01
Motivated by recent experimental observations of size quantization of electron energy levels in graphene quantum dots [7] we investigate the level statistics in the simplest tight-binding model for different dot shapes by computer simulation. The results are in a reasonable agreement with the experi
Haris, K.; Pai, Archana
2016-05-01
In this article, we revisit the coherent gravitational wave search problem of compact binary coalescences with multidetector network consisting of advanced interferometers like LIGO-Virgo. Based on the loss of the optimal multidetector signal-to-noise ratio (SNR), we construct a hybrid statistic as a best of maximum-likelihood-ratio (MLR) statistic tuned for face-on and face-off binaries. The statistical properties of the hybrid statistic is studied. The performance of this hybrid statistic is compared with that of the coherent MLR statistic for generic inclination angles. Owing to the single synthetic data stream, the hybrid statistic gives few false alarms compared to the multidetector MLR statistic and small fractional loss in the optimum SNR for a large range of binary inclinations. We demonstrate that, for a LIGO-Virgo network and binary inclination ɛ 11 0 ° , the hybrid statistic captures more than 98% of the network optimum matched filter SNR with a low false alarm rate. The Monte Carlo exercise with two distributions of incoming inclination angles—namely, U [cos ɛ ] and a more realistic distribution proposed by B. F. Schutz [Classical Quantum Gravity 28, 125023 (2011)]—are performed with the hybrid statistic and give approximately 5% and 7% higher detection probabilities, respectively, compared to the two stream multidetector MLR statistic for a fixed false alarm probability of 1 0-5.
Characteristics of level-spacing statistics in chaotic graphene billiards.
Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso
2011-03-01
A fundamental result in nonrelativistic quantum nonlinear dynamics is that the spectral statistics of quantum systems that possess no geometric symmetry, but whose classical dynamics are chaotic, are described by those of the Gaussian orthogonal ensemble (GOE) or the Gaussian unitary ensemble (GUE), in the presence or absence of time-reversal symmetry, respectively. For massless spin-half particles such as neutrinos in relativistic quantum mechanics in a chaotic billiard, the seminal work of Berry and Mondragon established the GUE nature of the level-spacing statistics, due to the combination of the chirality of Dirac particles and the confinement, which breaks the time-reversal symmetry. A question is whether the GOE or the GUE statistics can be observed in experimentally accessible, relativistic quantum systems. We demonstrate, using graphene confinements in which the quasiparticle motions are governed by the Dirac equation in the low-energy regime, that the level-spacing statistics are persistently those of GOE random matrices. We present extensive numerical evidence obtained from the tight-binding approach and a physical explanation for the GOE statistics. We also find that the presence of a weak magnetic field switches the statistics to those of GUE. For a strong magnetic field, Landau levels become influential, causing the level-spacing distribution to deviate markedly from the random-matrix predictions. Issues addressed also include the effects of a number of realistic factors on level-spacing statistics such as next nearest-neighbor interactions, different lattice orientations, enhanced hopping energy for atoms on the boundary, and staggered potential due to graphene-substrate interactions.
Level Statistics of SU(3)-SU(3)* Transitional Region
Jafarizadeh, M A; Sabri, H; gavifekr, P Hossein nezhade; Ranjbar, Z
2012-01-01
The level statistics of SU(3)-SU(3)* transitional region of IBM is described by the nearest neighbor spacing distribution statistics. The energy levels are determined by using the SO(6)representation of eigenstates. By employing the MLE technique, the parameter of Abul-Magd distribution is estimated where suggest less regular dynamics for transitional region in compare to dynamical symmetry limits. Also, the O(6)dynamical symmetry which is known as the critical point of this transitional region, describes a deviation to more regular dynamics.
Study of statistical properties of hybrid statistic in coherent multi-detector CBC Search
Haris, K
2015-01-01
In this article, we revisit the problem of coherent multi-detector search of gravitational wave from compact binary coalescence with Neutron stars and Black Holes using advanced interferometers like LIGO-Virgo. Based on the loss of optimal multi-detector signal-to-noise ratio (SNR), we construct a hybrid statistic as a best of maximum-likelihood-ratio(MLR) statistic tuned for face-on and face-off binaries. The statistical properties of the hybrid statistic is studied. The performance of this hybrid statistic is compared with that of the coherent MLR statistic for generic inclination angles. Owing to the single synthetic data stream, the hybrid statistic gives low false alarms compared to the multi-detector MLR statistic and small fractional loss in the optimum SNR for a large range of binary inclinations. We have demonstrated that for a LIGO-Virgo network and binary inclination, \\epsilon 110 deg., the hybrid statistic captures more than 98% of network optimum matched filter SNR with low false alarm rate. The...
Level Statistics and Specific Heat of Metallic Nano-Particles
Institute of Scientific and Technical Information of China (English)
程南璞; 陈志谦; 陈洪
2003-01-01
The thermodynamic properties of an ensemble of metallic nano-particles are affected by the level distribution and the level correlation between the discrete electronic energy levels. We numerically calculate the specific heat of metallic nano-particles in the canonical ensemble with an odd or even number of electrons by considering the effects of the level distribution and the level correlation. The behaviour of the specific heat at low and high temperatures, compared with the average nearest-neighbour level spacing, is also investigated.
Avoided-level-crossing statistics in open chaotic billiards.
Poli, Charles; Dietz, Barbara; Legrand, Olivier; Mortessagne, Fabrice; Richter, Achim
2009-09-01
We investigate a two-level model with a large number of open decay channels in order to describe avoided level crossing statistics in open chaotic billiards. This model allows us to describe the fundamental changes in the probability distribution of the avoided level crossings compared with the closed case. Explicit expressions are derived for systems with preserved and broken time-reversal symmetry. We find that the decay process induces a modification at small spacings of the probability distribution of the avoided level crossings due to an attraction of the resonances. The theoretical predictions are in complete agreement with the recent experimental results of Dietz [Phys. Rev. E 73, 035201 (2006)].
Level-Statistics of Disordered Systems: a Single Parametric Formulation
Shukla, Pragya
2002-01-01
We find that the statistics of levels undergoing metal-insulator transition in systems with multi-parametric Gaussian disorders behaves in a way similar to that of the single parametric Brownian ensembles. The latter appear during aPoisson $\\to$ Wigner-Dyson transition, driven by a random perturbation. The analogy provides the analytical evidence for the single parameter scaling behaviour in disordered systems as well as a tool to obtain the level-correlations at the critical point for a wide...
Sparse array design using statistical restricted isometry property.
Gaumond, Charles F; Edelmann, Geoffrey F
2013-08-01
The numerical application of the statistical reduced isometry property (StRIP) and statistical null space property (SNSP) is presented and demonstrated for the design of underwater acoustic line arrays. This recent approach predicts the theoretical utility of specific subsampled arrays for compressive sensing. Three subsamplings are presented: Random, Golomb, and Wichmann. The Golomb array has no repeated spacings. The Wichmann array includes every possible interval of spacings. The SNSP is shown insensitive to the cases presented. The StRIP of the Golomb array predicts superior invertibility and is shown to perform well using at-sea data.
Phase-locking-level statistics of coupled random fiber lasers.
Fridman, Moti; Pugatch, Rami; Nixon, Micha; Friesem, Asher A; Davidson, Nir
2012-10-01
We measure the statistics of phase locking levels of coupled fiber lasers with fluctuating cavity lengths. We found that the measured distribution of the phase locking level of such coupled lasers can be described by the generalized extreme value distribution. For large number of lasers the distribution of the phase locking level can be approximated by a Gumbel distribution. We present a simple model, based on the spectral response of coupled lasers, and the calculated results are in good agreement with the experimental results.
Statistical properties of alternative national forest inventory area estimators
Francis Roesch; John Coulston; Andrew D. Hill
2012-01-01
The statistical properties of potential estimators of forest area for the USDA Forest Service's Forest Inventory and Analysis (FIA) program are presented and discussed. The current FIA area estimator is compared and contrasted with a weighted mean estimator and an estimator based on the Polya posterior, in the presence of nonresponse. Estimator optimality is...
Statistical data for the tensile properties of natural fibre composites
Directory of Open Access Journals (Sweden)
J.P. Torres
2017-06-01
Full Text Available This article features a large statistical database on the tensile properties of natural fibre reinforced composite laminates. The data presented here corresponds to a comprehensive experimental testing program of several composite systems including: different material constituents (epoxy and vinyl ester resins; flax, jute and carbon fibres, different fibre configurations (short-fibre mats, unidirectional, and plain, twill and satin woven fabrics and different fibre orientations (0°, 90°, and [0,90] angle plies. For each material, ~50 specimens were tested under uniaxial tensile loading. Here, we provide the complete set of stress–strain curves together with the statistical distributions of their calculated elastic modulus, strength and failure strain. The data is also provided as support material for the research article: “The mechanical properties of natural fibre composite laminates: A statistical study” [1].
Statistical properties of high-lying chaotic eigenstates
Li, B; Li, Baowen; Robnik, Marko
1995-01-01
We study the statistical properties of the high-lying chaotic eigenstates (200,000 and above) which are deep in the semiclassical regime. The system we are analyzing is the billiard system inside the region defined by the quadratic (complex) conformal map of the unit disk as introduced by Robnik (1983). We are using Heller's method of plane wave decomposition of the numerical eigenfunctions, and perform extensive statistical analysis with the following conclusions: (1) The local average probability density is in excellent agreement with the microcanonical assumption and all statistical properties are also in excellent agreement with the Gaussian random model; \\qquad (2) The autocorrelation function is found to be strongly direction dependent and only after averaging over all directions agrees well with Berry's (1977) prediction; \\qquad (3) Although the scars of unstable classical periodic orbits (in such ergodic regime) are expected to exist, so far we have not found any (around 200,000th state) but a scar-li...
Image Statistics and the Representation of Material Properties in the Visual Cortex.
Baumgartner, Elisabeth; Gegenfurtner, Karl R
2016-01-01
We explored perceived material properties (roughness, texturedness, and hardness) with a novel approach that compares perception, image statistics and brain activation, as measured with fMRI. We initially asked participants to rate 84 material images with respect to the above mentioned properties, and then scanned 15 of the participants with fMRI while they viewed the material images. The images were analyzed with a set of image statistics capturing their spatial frequency and texture properties. Linear classifiers were then applied to the image statistics as well as the voxel patterns of visually responsive voxels and early visual areas to discriminate between images with high and low perceptual ratings. Roughness and texturedness could be classified above chance level based on image statistics. Roughness and texturedness could also be classified based on the brain activation patterns in visual cortex, whereas hardness could not. Importantly, the agreement in classification based on image statistics and brain activation was also above chance level. Our results show that information about visual material properties is to a large degree contained in low-level image statistics, and that these image statistics are also partially reflected in brain activity patterns induced by the perception of material images.
Quantum-statistical property of optical diode based on cavity QED
Li, Haozhen; Xu, Jingping; Wang, Da-Wei; Xia, Xiuwen; Yang, Yaping; Zhu, Shiyao
2017-07-01
An optical diode made of an asymmetric cavity containing a two-level atom is investigated. We focus on the quantum-statistical property of the transmitted field with nonclassical light input. Both coherent and squeezed light inputs have been considered. The results show that the transmitted contrast of such optical diode is independent of the statistical properties of the incident light but is only sensitive to its intensity. On the other hand, the quantum-statistical property, i.e., the squeezing, of the transmitted field strongly depends on the statistical properties and directions of the incident light. For squeezed light input, the degree of the squeezing of the transmitted field can be remarkably enhanced. Moreover, the squeezing of the amplitude quadrature of the incident light can be transferred to the phase quadrature due to the coupling of the light and the atom.
Statistical thermodynamics understanding the properties of macroscopic systems
Fai, Lukong Cornelius
2012-01-01
Basic Principles of Statistical PhysicsMicroscopic and Macroscopic Description of StatesBasic PostulatesGibbs Ergodic AssumptionGibbsian EnsemblesExperimental Basis of Statistical MechanicsDefinition of Expectation ValuesErgodic Principle and Expectation ValuesProperties of Distribution FunctionRelative Fluctuation of an Additive Macroscopic ParameterLiouville TheoremGibbs Microcanonical EnsembleMicrocanonical Distribution in Quantum MechanicsDensity MatrixDensity Matrix in Energy RepresentationEntropyThermodynamic FunctionsTemperatureAdiabatic ProcessesPressureThermodynamic IdentityLaws of Th
Statistical Properties of Fluctuations: A Method to Check Market Behavior
Panigrahi, Prasanta K; Manimaran, P; Ahalpara, Dilip P
2009-01-01
We analyze the Bombay stock exchange (BSE) price index over the period of last 12 years. Keeping in mind the large fluctuations in last few years, we carefully find out the transient, non-statistical and locally structured variations. For that purpose, we make use of Daubechies wavelet and characterize the fractal behavior of the returns using a recently developed wavelet based fluctuation analysis method. the returns show a fat-tail distribution as also weak non-statistical behavior. We have also carried out continuous wavelet as well as Fourier power spectral analysis to characterize the periodic nature and correlation properties of the time series.
Level statistics in arithmetical and pseudo-arithmetical chaos
Energy Technology Data Exchange (ETDEWEB)
Braun, Petr; Haake, Fritz, E-mail: Petr.Braun@uni-due.d [Fachbereich Physik, Universitaet Duisburg-Essen, 47048 Duisburg (Germany)
2010-07-02
We investigate a long-standing riddle in quantum chaos, posed by certain fully chaotic billiards with constant negative curvature whose periodic orbits are highly degenerate in length. Depending on the boundary conditions for the quantum wavefunctions, the energy spectra either have uncorrelated levels usually associated with classical integrability or conform to the 'universal' Wigner-Dyson type although the classical dynamics in both cases is the same. The resolution turns out surprisingly simple. The Maslov indices of orbits within multiplets of degenerate length either yield equal phases for the respective Feynman amplitudes (and thus Poissonian level statistics) or give rise to amplitudes with uncorrelated phases (leading to Wigner-Dyson level correlations). The recent semiclassical explanation of spectral universality in quantum chaos is thus extended to the latter case of 'pseudo-arithmetical' chaos. (fast track communication)
Statistical Properties of the Reaistic Model Spectra for Doubly-Odd Nuclei
Institute of Scientific and Technical Information of China (English)
程南璞; 陈志谦; 陈洪
2002-01-01
The statistical properties of the energy levels calculated for the doubly-odd nuclei 84 y, 124Cs and 156Tb within the queasiparticle plus axially symmetric rotor model are studied by means of the two standard statistical tests of random-matrix theory, i.e. the distribution function p ( s) of the nearest-neighbour level spacings and the spectral rigidity (Δ3 statistics). We also investigate the Brody distribution function pB (s) with a single parameter that describes the chaotic degree of the systematic dynamics and the transition behaviour of the spectral fluctuations between Poisson and Gauss orthogonal ensemble limits.
Thermodynamics and statistical mechanics. [thermodynamic properties of gases
1976-01-01
The basic thermodynamic properties of gases are reviewed and the relations between them are derived from the first and second laws. The elements of statistical mechanics are then formulated and the partition function is derived. The classical form of the partition function is used to obtain the Maxwell-Boltzmann distribution of kinetic energies in the gas phase and the equipartition of energy theorem is given in its most general form. The thermodynamic properties are all derived as functions of the partition function. Quantum statistics are reviewed briefly and the differences between the Boltzmann distribution function for classical particles and the Fermi-Dirac and Bose-Einstein distributions for quantum particles are discussed.
Fractional-power-law level statistics due to dynamical tunneling.
Bäcker, Arnd; Ketzmerick, Roland; Löck, Steffen; Mertig, Normann
2011-01-14
For systems with a mixed phase space we demonstrate that dynamical tunneling universally leads to a fractional power law of the level-spacing distribution P(s) over a wide range of small spacings s. Going beyond Berry-Robnik statistics, we take into account that dynamical tunneling rates between the regular and the chaotic region vary over many orders of magnitude. This results in a prediction of P(s) which excellently describes the spectral data of the standard map. Moreover, we show that the power-law exponent is proportional to the effective Planck constant h(eff).
Statistical properties of ultrasound speckles reflected from an interface
Institute of Scientific and Technical Information of China (English)
WU Yanyang; ZHU Hongmao; HU Peng; LIU Chung
2003-01-01
The first- and second-order statistical properties of ultrasound speckles reflectedfrom an interface are studied theoretically and experimentally. A theoretical model for predict-ing statistical properties of ultrasound speckles is constructed based on the Fresnel-Huygensprinciple and three basic assumptions. Distributions of amplitude and phase of ultrasoundspeckles in a scattering space are studied. And the study shows that they are in the form ofRayleigh and uniform distribution respectively. Using the proposed model, the average trans-verse size of the speckles within a scattering domain which are received by a focus probe isinvestigated. The average transverse size is found to be dependent on the characteristics ofthe measuring system only, and does not vary with the position in the domain. To verify theapplicability of the theoretical model, a special experimental set-up was designed and the cor-responding experiments were conducted for measuring the sound pressure of the ultrasoundspeckles reflected from an interface between water and Aluminium alloy. The numerical resultsare compared with the experimental ones. The comparison demonstrates that the theoreti-cal model and the three related assumptions are suitable for analysing statistical properties ofultrasound speckles reflected from an interface.
Non-Gaussian statistical properties of virtual breast phantoms
Abbey, Craig K.; Bakic, Predrag R.; Pokrajac, David D.; Maidment, Andrew D. A.; Eckstein, Miguel P.; Boone, John M.
2014-03-01
Images derived from a "phantom" are useful for characterizing the performance of imaging systems. In particular, the modulation transfer properties of imaging detectors are traditionally assessed by physical phantoms consisting of an edge. More recently researchers have come to realize that quantifying the effects of object variability can also be accomplished with phantoms in modalities such as breast imaging where anatomical structure may be the principal limitation in performance. This has driven development of virtual phantoms that can be used in simulation environments. In breast imaging, several such phantoms have been proposed. In this work, we analyze non-Gaussian statistical properties of virtual phantoms, and compare them to similar statistics from a database of breast images. The virtual phantoms assessed consist of three classes. The first is known as clustered-blob lumpy backgrounds. The second class is "binarized" textures which typically apply some sort of threshold to a stochastic 3D texture intended to represent the distribution of adipose and glandular tissue in the breast. The third approach comes from efforts at the University of Pennsylvania to directly simulate the 3D anatomy of the breast. We use Laplacian fractional entropy (LFE) as a measure of the non-Gaussian statistical properties of each simulation. Our results show that the simulation approaches differ considerably in LFE with very low scores for the clustered-blob lumpy background to very high values for the UPenn phantom. These results suggest that LFE may have value in developing and tuning virtual phantom simulation procedures.
LOWER LEVEL INFERENCE CONTROL IN STATISTICAL DATABASE SYSTEMS
Energy Technology Data Exchange (ETDEWEB)
Lipton, D.L.; Wong, H.K.T.
1984-02-01
An inference is the process of transforming unclassified data values into confidential data values. Most previous research in inference control has studied the use of statistical aggregates to deduce individual records. However, several other types of inference are also possible. Unknown functional dependencies may be apparent to users who have 'expert' knowledge about the characteristics of a population. Some correlations between attributes may be concluded from 'commonly-known' facts about the world. To counter these threats, security managers should use random sampling of databases of similar populations, as well as expert systems. 'Expert' users of the DATABASE SYSTEM may form inferences from the variable performance of the user interface. Users may observe on-line turn-around time, accounting statistics. the error message received, and the point at which an interactive protocol sequence fails. One may obtain information about the frequency distributions of attribute values, and the validity of data object names from this information. At the back-end of a database system, improved software engineering practices will reduce opportunities to bypass functional units of the database system. The term 'DATA OBJECT' should be expanded to incorporate these data object types which generate new classes of threats. The security of DATABASES and DATABASE SySTEMS must be recognized as separate but related problems. Thus, by increased awareness of lower level inferences, system security managers may effectively nullify the threat posed by lower level inferences.
Energy Level Statistics in Particle—Rotor Model
Institute of Scientific and Technical Information of China (English)
ZHOUXian－Rong; MENGJie; 等
2002-01-01
Energy level statistics of a system consisting of six particles interacting by delta force in a two-j model coupled with a deformed core is studied in particle-rotor model.For single-j shell (i13/2) and two-j shell (g7/2+d5/2) the exact energies for our statistical analysis are obtained from a full diagonalization of the Hamiltonian,whilt in two-j case (i13/2+g9/2) the configuration truncation is used.The nearest-neighbor distribution of energy levels and spectral rigidity are studied as the function of spin.The results of single-j shell are compared with those in two-j case.It is showed that the system becomes more regular when single-j space (i13/2) is replaced by two-j shell (g7/2+d5/2) although the basis size of the configuration space is unchanged.The degree of chaoticity of the system,however,changes slightly when configuration space is enlarged by extending single-j shell (i13/2) to two-j shell (i13/2+g9/2).
Energy Level Statistics in Particle-Rotor Model
Institute of Scientific and Technical Information of China (English)
ZHOU Xian-Rong; GUO Lu; MENG Jie; ZHAO En-Guang
2002-01-01
Energy level statistics of a system consisting of six particles interacting by delta force in a two-j modelcoupled with a deformed core is studied in particle-rotor model. For single-j shell (i13/2) and two-j shell (g7/2 + d5/2)the exact energies for our statistical analysis are obtained from a full diagonalization of the Hamiltonian, while in two-jcase (i13/2 + g9/2) the configuration truncation is used. The nearest-neighbor distribution of energy levels and spectralrigidity are studied as the function of spin. The results of single-j shell are compared with those in two-j case. It isshowed that the system becomes more regular when single-j space (i13/2) is replaced by two-j shell (g7/2 +d5/2) althoughthe basis size of the configuration space is unchanged. The degree of chaoticity of the system, however, changes slightlywhen configuration space is enlarged by extending single-j shell (i13/2) to two-j shell (i13/2 + g9/2).
The statistical distribution of aerosol properties in sourthern West Africa
Haslett, Sophie; Taylor, Jonathan; Flynn, Michael; Bower, Keith; Dorsey, James; Crawford, Ian; Brito, Joel; Denjean, Cyrielle; Bourrianne, Thierry; Burnet, Frederic; Batenburg, Anneke; Schulz, Christiane; Schneider, Johannes; Borrmann, Stephan; Sauer, Daniel; Duplissy, Jonathan; Lee, James; Vaughan, Adam; Coe, Hugh
2017-04-01
The population and economy in southern West Africa have been growing at an exceptional rate in recent years and this trend is expected to continue, with the population projected to more than double to 800 million by 2050. This will result in a dramatic increase in anthropogenic pollutants, already estimated to have tripled between 1950 and 2000 (Lamarque et al., 2010). It is known that aerosols can modify the radiative properties of clouds. As such, the entrainment of anthropogenic aerosol into the large banks of clouds forming during the onset of the West African Monsoon could have a substantial impact on the region's response to climate change. Such projections, however, are greatly limited by the scarcity of observations in this part of the world. As part of the Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa (DACCIWA) project, three research aircraft were deployed, each carrying equipment capable of measuring aerosol properties in-situ. Instrumentation included Aerosol Mass Spectrometers (AMS), Single Particle Soot Photometers (SP2), Condensation Particle Counters (CPC) and Scanning Mobility Particle Sizers (SMPS). Throughout the intensive aircraft campaign, 155 hours of scientific flights covered an area including large parts of Benin, Togo, Ghana and parts of Côte D'Ivoire. Approximately 70 hours were dedicated to the measurement of cloud-aerosol interactions, with many other flights producing data contributing towards this objective. Using datasets collected during this campaign period, it is possible to build a robust statistical understanding of aerosol properties in this region for the first time, including size distributions and optical and chemical properties. Here, we describe preliminary results from aerosol measurements on board the three aircraft. These have been used to describe aerosol properties throughout the region and time period encompassed by the DACCIWA aircraft campaign. Such statistics will be invaluable for improving future
Ten Years of Cloud Properties from MODIS: Global Statistics and Use in Climate Model Evaluation
Platnick, Steven E.
2011-01-01
The NASA Moderate Resolution Imaging Spectroradiometer (MODIS), launched onboard the Terra and Aqua spacecrafts, began Earth observations on February 24, 2000 and June 24,2002, respectively. Among the algorithms developed and applied to this sensor, a suite of cloud products includes cloud masking/detection, cloud-top properties (temperature, pressure), and optical properties (optical thickness, effective particle radius, water path, and thermodynamic phase). All cloud algorithms underwent numerous changes and enhancements between for the latest Collection 5 production version; this process continues with the current Collection 6 development. We will show example MODIS Collection 5 cloud climatologies derived from global spatial . and temporal aggregations provided in the archived gridded Level-3 MODIS atmosphere team product (product names MOD08 and MYD08 for MODIS Terra and Aqua, respectively). Data sets in this Level-3 product include scalar statistics as well as 1- and 2-D histograms of many cloud properties, allowing for higher order information and correlation studies. In addition to these statistics, we will show trends and statistical significance in annual and seasonal means for a variety of the MODIS cloud properties, as well as the time required for detection given assumed trends. To assist in climate model evaluation, we have developed a MODIS cloud simulator with an accompanying netCDF file containing subsetted monthly Level-3 statistical data sets that correspond to the simulator output. Correlations of cloud properties with ENSO offer the potential to evaluate model cloud sensitivity; initial results will be discussed.
Photon statistical properties of the cavity field in the two-atom Jaynes-Cummings model
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The model that two two-level atoms interact with a singel-mode cavity is studied. The exact solution of the time evolution operator for the two-atom Jaynes-Cummings model is presented by the bare-states approach. Furthermore, we investigate the dynamical properties of the photon statistics of the cavity field, and obtain a number of novel features.
Statistical properties of the universal limit map of grazing bifurcations
Li, Denghui; Chen, Hebai; Xie, Jianhua
2016-09-01
In this paper, the statistical properties of an interval map, having a square-root singular point which characterizes grazing bifurcations of impact oscillators, are studied. Firstly, we show that in some parameter regions the map admits an induced Markov structure with an exponential decay tail of the return times. Then we prove that the map has a unique mixing absolutely continuous invariant probability measure. Finally, by applying the Markov tower method, we prove that exponential decay of correlations and the central limit theorem hold for Hölder continuous observations.
On statistical properties of Jizba-Arimitsu hybrid entropy
Çankaya, Mehmet Niyazi; Korbel, Jan
2017-06-01
Jizba-Arimitsu entropy (also called hybrid entropy) combines axiomatics of Rényi and Tsallis entropy. It has many common properties with them, on the other hand, some aspects as e.g., MaxEnt distributions, are different. In this paper, we discuss statistical properties of hybrid entropy. We define hybrid entropy for continuous distributions and its relation to discrete entropy. Additionally, definition of hybrid divergence and its connection to Fisher metric is also presented. Interestingly, Fisher metric connected to hybrid entropy differs from corresponding Fisher metrics of Rényi and Tsallis entropy. This motivates us to introduce average hybrid entropy, which can be understood as an average between Tsallis and Rényi entropy.
Statistically significant data base of rock properties for geothermal use
Koch, A.; Jorand, R.; Clauser, C.
2009-04-01
The high risk of failure due to the unknown properties of the target rocks at depth is a major obstacle for the exploration of geothermal energy. In general, the ranges of thermal and hydraulic properties given in compilations of rock properties are too large to be useful to constrain properties at a specific site. To overcome this problem, we study the thermal and hydraulic rock properties of the main rock types in Germany in a statistical approach. An important aspect is the use of data from exploration wells that are largely untapped for the purpose of geothermal exploration. In the current project stage, we have been analyzing mostly Devonian and Carboniferous drill cores from 20 deep boreholes in the region of the Lower Rhine Embayment and the Ruhr area (western North Rhine Westphalia). In total, we selected 230 core samples with a length of up to 30 cm from the core archive of the State Geological Survey. The use of core scanning technology allowed the rapid measurement of thermal conductivity, sonic velocity, and gamma density under dry and water saturated conditions with high resolution for a large number of samples. In addition, we measured porosity, bulk density, and matrix density based on Archimedes' principle and pycnometer analysis. As first results we present arithmetic means, medians and standard deviations characterizing the petrophysical properties and their variability for specific lithostratigraphic units. Bi- and multimodal frequency distributions correspond to the occurrence of different lithologies such as shale, limestone, dolomite, sandstone, siltstone, marlstone, and quartz-schist. In a next step, the data set will be combined with logging data and complementary mineralogical analyses to derive the variation of thermal conductivity with depth. As a final result, this may be used to infer thermal conductivity for boreholes without appropriate core data which were drilled in similar geological settings.
Statistical properties of Fourier-based time-lag estimates
Epitropakis, A
2016-01-01
Context: The study of X-ray time-lag spectra in AGN is currently an active research area, as it has the potential to illuminate the physics and geometry of the innermost region (i.e. close to the putative super-massive black hole) in these objects. In order to obtain reliable information from these studies, the statistical properties of time-lags estimated from data must be known as accurately as possible. Aims: We investigated the statistical properties of Fourier-based time-lag estimates (i.e. based on the cross-periodogram), using evenly sampled time series with no missing points. Our aim is to provide practical "guidelines" on estimating time-lags which are minimally biased (i.e. whose mean is close to their intrinsic value) and have known errors. Methods: Our investigation is based on both analytical work and extensive numerical simulations. The latter consisted of generating artificial time series with various signal-to-noise ratios and sampling patterns/durations similar to those offered by AGN observa...
On the statistical properties and tail risk of violent conflicts
Cirillo, Pasquale; Taleb, Nassim Nicholas
2016-06-01
We examine statistical pictures of violent conflicts over the last 2000 years, providing techniques for dealing with the unreliability of historical data. We make use of a novel approach to deal with fat-tailed random variables with a remote but nonetheless finite upper bound, by defining a corresponding unbounded dual distribution (given that potential war casualties are bounded by the world population). This approach can also be applied to other fields of science where power laws play a role in modeling, like geology, hydrology, statistical physics and finance. We apply methods from extreme value theory on the dual distribution and derive its tail properties. The dual method allows us to calculate the real tail mean of war casualties, which proves to be considerably larger than the corresponding sample mean for large thresholds, meaning severe underestimation of the tail risks of conflicts from naive observation. We analyze the robustness of our results to errors in historical reports. We study inter-arrival times between tail events and find that no particular trend can be asserted. All the statistical pictures obtained are at variance with the prevailing claims about "long peace", namely that violence has been declining over time.
Atomic properties in hot plasmas from levels to superconfigurations
Bauche, Jacques; Peyrusse, Olivier
2015-01-01
This book is devoted to the calculation of hot-plasma properties which generally requires a huge number of atomic data. It is the first book that combines information on the details of the basic atomic physics and its application to atomic spectroscopy with the use of the relevant statistical approaches. Information like energy levels, radiative rates, collisional and radiative cross-sections, etc., must be included in equilibrium or non-equilibrium models in order to describe both the atomic-population kinetics and the radiative properties. From the very large number of levels and transitions involved in complex ions, some statistical (global) properties emerge. The book presents a coherent set of concepts and compact formulas suitable for tractable and accurate calculations. The topics addressed are: radiative emission and absorption, and a dozen of other collisional and radiative processes; transition arrays between level ensembles (configurations, superconfigurations); effective temperatures of configurat...
Statistical properties of the yuan exchange rate index
Wang, Dong-Hua; Yu, Xiao-Wen; Suo, Yuan-Yuan
2012-06-01
We choice the yuan exchange rate index based on a basket of currencies as the effective exchange rate of the yuan and investigate the statistical properties of the yuan exchange rate index after China's exchange rate system reform on the 21st July 2005. After dividing the time series into two parts according to the change in the yuan exchange rate regime in July 2008, we compare the statistical properties of the yuan exchange rate index during these two periods. We find that the distribution of the two return series has the exponential form. We also perform the detrending moving average analysis (DMA) and the multifractal detrending moving average analysis (MFDMA). The two periods possess different degrees of long-range correlations, and the multifractal nature is also unveiled in these two time series. Significant difference is found in the scaling exponents τ(q) and singularity spectra f(α) of the two periods obtained from the MFDMA analysis. Besides, in order to detect the sources of multifractality, shuffling and phase randomization procedures are applied to destroy the long-range temporal correlation and fat-tailed distribution of the yuan exchange rate index respectively. We find that the fat-tailedness plays a critical role in the sources of multifractality in the first period, while the long memory is the major cause in the second period. The results suggest that the change in China's exchange rate regime in July 2008 gives rise to the different multifractal properties of the yuan exchange rate index in these two periods, and thus has an effect on the effective exchange rate of the yuan after the exchange rate reform on the 21st July 2005.
On the statistical analysis of trend in tropospheric ozone levels
Vaquera-Huerta, Humberto
1997-11-01
This paper is a study of methodology to investigate trends in ozone levels in urban areas. Three methods are studied; two parametric (NHPP, and GPD) and one nonparametric. The nonhomogeneous Poisson process (NHPP) approach: This method is based on the idea that the number of exceedances over a high threshold follows a Poisson distribution. In this method the detection of trend is approached by estimating the intensity function of the process. The intensity function is estimated using parametric and nonparametric methods. A general parametric function over time for the rate of a NHPP is proposed in order to test for nonexponential patterns. The Generalized Pareto Distribution approach (GPD): In this method the detection of trend in ozone is approached by considering that the magnitude of the exceedances over a high threshold follows a generalized Pareto distribution. The nonparametric statistical approach: A test for trend and a nonparametric estimator of a trend parameter were studied. The asymptotic distribution of the estimator is also provided. The nonparametric estimator is compared with the least squares estimator. The three methods are studied empirically using a Monte Carlo method. Some insight into how well these methods perform is obtained. Also, the use of each method is illustrated by examples with ozone data. The results of this study show that NHPP performs very well as a method to detect ozone trends. The GPD and the nonparametric approaches had low power for detecting trends in simulation experiments.
Statistical properties and universality in earthquake and solar flare occurrence
de Arcangelis, L.; Lippiello, E.; Godano, C.; Nicodemi, M.
2008-08-01
Earthquakes are phenomena of great complexity, however some simple general laws govern the statistics of their occurrence. Some of these most important laws exhibit scale invariance, as the Gutenberg-Richter law and the Omori law. The origin of these scaling behaviours is not yet fully understood and a natural fondamental question concerns the existence of these features also in other complex phenomena. A direct inspection of experimental catalogues has shown that the stochastic processes underlying solar flare and earthquake occurrence have universal properties. Another intensively debated question is the existence of correlations between magnitudes of subsequent earthquakes. Our recent analysis of the Southern California Catalogue has shown that non-zero magnitude correlations exist. A branching model based on a dynamical scaling hypothesis, relating magnitude to time, reproduces the hierarchical organization in time and magnitude of events and the observed magnitude correlations.
Dynamical topology and statistical properties of spatiotemporal chaos.
Zhuang, Quntao; Gao, Xun; Ouyang, Qi; Wang, Hongli
2012-12-01
For spatiotemporal chaos described by partial differential equations, there are generally locations where the dynamical variable achieves its local extremum or where the time partial derivative of the variable vanishes instantaneously. To a large extent, the location and movement of these topologically special points determine the qualitative structure of the disordered states. We analyze numerically statistical properties of the topologically special points in one-dimensional spatiotemporal chaos. The probability distribution functions for the number of point, the lifespan, and the distance covered during their lifetime are obtained from numerical simulations. Mathematically, we establish a probabilistic model to describe the dynamics of these topologically special points. In spite of the different definitions in different spatiotemporal chaos, the dynamics of these special points can be described in a uniform approach.
Statistical properties of the ice particle distribution in stratiform clouds
Delanoe, J.; Tinel, C.; Testud, J.
2003-04-01
This paper presents an extensive analysis of several microphysical data bases CEPEX, EUCREX, CLARE and CARL to determine statistical properties of the Particle Size Distribution (PSD). The data base covers different type of stratiform clouds : tropical cirrus (CEPEX), mid-latitude cirrus (EUCREX) and mid-latitude cirrus and stratus (CARL,CLARE) The approach for analysis uses the concept of normalisation of the PSD developed by Testud et al. (2001). The normalization aims at isolating three independent characteristics of the PSD : its "intrinsic" shape, the "average size" of the spectrum and the ice water content IWC, "average size" is meant the mean mass weighted diameter. It is shown that concentration should be normalized by N_0^* proportional to IWC/D_m^4. The "intrinsic" shape is defined as F(Deq/D_m)=N(Deq)/N_0^* where Deq is the equivalent melted diameter. The "intrinsic" shape is found to be very stable in the range 001.5, more scatter is observed, but future analysis should decide if it is representative of real physical variation or statistical "error" due to counting problem. Considering an overall statistics over the full data base, a large scatter of the N_0^* against Dm plot is found. But in the case of a particular event or a particular leg of a flight, the N_0^* vs. Dm plot is much less scattered and shows a systematic trend for decaying of N_0^* when Dm increases. This trend is interpreted as the manifestation of the predominance of the aggregation process. Finally an important point for cloud remote sensing is investigated : the normalised relationships IWC/N_0^* against Z/N_0^* is much less scattered that the classical IWC against Z the radar reflectivity factor.
Statistical Properties of SGR 1806-20 Bursts.
Göğüş; Woods; Kouveliotou; van Paradijs J; Briggs; Duncan; Thompson
2000-04-01
We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary Explorer. We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.76, and 1.67, respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with a peak at 103 s. There is no correlation between the burst intensity and either the waiting times until the next burst or the time elapsed since the previous burst. In all these statistical properties, SGR 1806-20 bursts resemble a self-organized critical system, similar to earthquakes and solar flares. Our results thus support the hypothesis that the energy source for soft gamma repeater bursts is crustquakes due to the evolving, strong magnetic field of the neutron star, rather than any accretion or nuclear power.
Statistical Properties of SGR 1806-20 Bursts
Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa; VanParadijs, Jan; Briggs, Michael S.; Duncan, Robert C.; Thompson, Christopher
2000-01-01
We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary, Explorer. We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.76, and 1.67, respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with a peak at 103 s. There is no correlation between the burst intensity and either the waiting times until the next burst or the time elapsed since the previous burst. In all these statistical properties, SGR 1806-20 bursts resemble a self-organized critical system, similar to earthquakes and solar flares. Our results thus support the hypothesis that the energy source for soft gamma repeater bursts is crustquakes due to the evolving, strong magnetic field of the neutron star, rather than any accretion or nuclear power.
Statistical Properties of SGR 1900+14 Bursts
Gogus, Ersin; Woods, Peter M.; Kouveliotou, Chryssa; VanParadijs, Jan
1999-01-01
We study the statistics of soft gamma repeater (SGR) bursts using a database of 187 events detected with BATSE and 837 events detected with the Rossi X-Ray Timing Explorer Proportional Counter Array: all events are from SGR 1900+14 during its 1998-1999 active phase. We find that the fluence or energy distribution of bursts is consistent with a power law of index 1.66, over 4 orders of magnitude. This scale-free distribution resembles the Gutenberg-Richter law for earthquakes and gives evidence for self-organized criticality in SGRS. The distribution of time intervals between successive bursts from SGR 1900+14 is consistent with a lognormal distribution. There is no correlation between burst intensity and the waiting times till the next burst, but there is some evidence for a correlation between burst intensity and the time elapsed since the previous burst. We also find a correlation between the duration and the energy of the bursts, but with significant scatter. In all these statistical properties, SGR bursts resemble earthquakes and solar flares more closely than they resemble any known accretion-powered or nuclear-powered phenomena. Thus, our analysis lends support to the hypothesis that the energy source for SGR bursts is internal to the neutron star and plausibly magnetic.
Predicting statistical properties of open reading frames in bacterial genomes.
Directory of Open Access Journals (Sweden)
Katharina Mir
Full Text Available An analytical model based on the statistical properties of Open Reading Frames (ORFs of eubacterial genomes such as codon composition and sequence length of all reading frames was developed. This new model predicts the average length, maximum length as well as the length distribution of the ORFs of 70 species with GC contents varying between 21% and 74%. Furthermore, the number of annotated genes is predicted with high accordance. However, the ORF length distribution in the five alternative reading frames shows interesting deviations from the predicted distribution. In particular, long ORFs appear more often than expected statistically. The unexpected depletion of stop codons in these alternative open reading frames cannot completely be explained by a biased codon usage in the +1 frame. While it is unknown if the stop codon depletion has a biological function, it could be due to a protein coding capacity of alternative ORFs exerting a selection pressure which prevents the fixation of stop codon mutations. The comparison of the analytical model with bacterial genomes, therefore, leads to a hypothesis suggesting novel gene candidates which can now be investigated in subsequent wet lab experiments.
Statistical properties of the personal social network in the Facebook
Guo, Q.; Shao, F.; Hu, Z. L.; Liu, J. G.
2013-10-01
The statistical properties of the user interaction behaviors in a city have great significance for developing the network marketing strategy, promoting personalized service and so on. In this paper, we investigate the interaction property of the users from New Orleans network in the Facebook, and find that one's out-degree and in-degree are approximately the same. In addition, when the number of a user friends is less than 65, the number of their posts would linearly grow with the slope 4.2, but when one user's friends are more than 65, their posts would grow with the slope 2.1. Further, the average link weight is relatively flat when the out-degree ranges from 28 to 65, and before or after the section it is on the rise or in decline, respectively, from which we can conclude that one could not maintain stable and meaningful relationships with more than 65 people in a single city. We present a null model to reshuffle the network to guarantee that the empirical results are not obtained by accident. The result obtained after reshuffling suggests that there exists a limit that restricts people's social activities.
Likert scales, levels of measurement and the "laws" of statistics.
Norman, Geoff
2010-12-01
Reviewers of research reports frequently criticize the choice of statistical methods. While some of these criticisms are well-founded, frequently the use of various parametric methods such as analysis of variance, regression, correlation are faulted because: (a) the sample size is too small, (b) the data may not be normally distributed, or (c) The data are from Likert scales, which are ordinal, so parametric statistics cannot be used. In this paper, I dissect these arguments, and show that many studies, dating back to the 1930s consistently show that parametric statistics are robust with respect to violations of these assumptions. Hence, challenges like those above are unfounded, and parametric methods can be utilized without concern for "getting the wrong answer".
Statistical properties of the normalized ice particle size distribution
Delanoë, Julien; Protat, Alain; Testud, Jacques; Bouniol, Dominique; Heymsfield, A. J.; Bansemer, A.; Brown, P. R. A.; Forbes, R. M.
2005-05-01
Testud et al. (2001) have recently developed a formalism, known as the "normalized particle size distribution (PSD)", which consists in scaling the diameter and concentration axes in such a way that the normalized PSDs are independent of water content and mean volume-weighted diameter. In this paper we investigate the statistical properties of the normalized PSD for the particular case of ice clouds, which are known to play a crucial role in the Earth's radiation balance. To do so, an extensive database of airborne in situ microphysical measurements has been constructed. A remarkable stability in shape of the normalized PSD is obtained. The impact of using a single analytical shape to represent all PSDs in the database is estimated through an error analysis on the instrumental (radar reflectivity and attenuation) and cloud (ice water content, effective radius, terminal fall velocity of ice crystals, visible extinction) properties. This resulted in a roughly unbiased estimate of the instrumental and cloud parameters, with small standard deviations ranging from 5 to 12%. This error is found to be roughly independent of the temperature range. This stability in shape and its single analytical approximation implies that two parameters are now sufficient to describe any normalized PSD in ice clouds: the intercept parameter N*0 and the mean volume-weighted diameter Dm. Statistical relationships (parameterizations) between N*0 and Dm have then been evaluated in order to reduce again the number of unknowns. It has been shown that a parameterization of N*0 and Dm by temperature could not be envisaged to retrieve the cloud parameters. Nevertheless, Dm-T and mean maximum dimension diameter -T parameterizations have been derived and compared to the parameterization of Kristjánsson et al. (2000) currently used to characterize particle size in climate models. The new parameterization generally produces larger particle sizes at any temperature than the Kristjánsson et al. (2000
Likert Scales, Levels of Measurement and the "Laws" of Statistics
Norman, Geoff
2010-01-01
Reviewers of research reports frequently criticize the choice of statistical methods. While some of these criticisms are well-founded, frequently the use of various parametric methods such as analysis of variance, regression, correlation are faulted because: (a) the sample size is too small, (b) the data may not be normally distributed, or (c) The…
Critical, statistical, and thermodynamical properties of lattice models
Energy Technology Data Exchange (ETDEWEB)
Varma, Vipin Kerala
2013-10-15
In this thesis we investigate zero temperature and low temperature properties - critical, statistical and thermodynamical - of lattice models in the contexts of bosonic cold atom systems, magnetic materials, and non-interacting particles on various lattice geometries. We study quantum phase transitions in the Bose-Hubbard model with higher body interactions, as relevant for optical lattice experiments of strongly interacting bosons, in one and two dimensions; the universality of the Mott insulator to superfluid transition is found to remain unchanged for even large three body interaction strengths. A systematic renormalization procedure is formulated to fully re-sum these higher (three and four) body interactions into the two body terms. In the strongly repulsive limit, we analyse the zero and low temperature physics of interacting hard-core bosons on the kagome lattice at various fillings. Evidence for a disordered phase in the Ising limit of the model is presented; in the strong coupling limit, the transition between the valence bond solid and the superfluid is argued to be first order at the tip of the solid lobe.
Statistical property of the Chandler wobble excitation function
Institute of Scientific and Technical Information of China (English)
LIAO Dechun; LIAO Xinhao; ZHOU Yonghong
2004-01-01
The Chandler wobble excitation function (hereinafter, geodetic excitation) is obtained by removing the seasonal components and low frequency components with periods from several years to decades from the polar motion excitation function derived from SPACE2002 series. The geophysical excitation functions of the individual AAM, OAM, HAM, and two combined excitations of the AAM + OAM and AAM + OAM + HAM at 1d, 5d, 1m and 3m intervals are statistically tested for the hypothesis of the normality, and then tested for the hypotheses of identical distribution between the geodetic and the geophysical excitations. The results show that, among the total 16 components of the two combined excitation functions at 1d, 5d, 1m and 3m intervals,most follow random normal processes, the hypotheses of identical distribution between the geodetic excitation and the two combined excitation are acceptable, while most of the hypotheses of identical distribution between the geodetic excitation and the individual excitations of the AAM, OAM, and HAM are rejectable.These results elucidate from a new point of view, that the excitations from AAM, OAM, and HAM are the main sources of the Chandler wobble, and the Chandler wobble excitation function is of a random normal property.
Hayslett, H T
1991-01-01
Statistics covers the basic principles of Statistics. The book starts by tackling the importance and the two kinds of statistics; the presentation of sample data; the definition, illustration and explanation of several measures of location; and the measures of variation. The text then discusses elementary probability, the normal distribution and the normal approximation to the binomial. Testing of statistical hypotheses and tests of hypotheses about the theoretical proportion of successes in a binomial population and about the theoretical mean of a normal population are explained. The text the
Statistical selection of tide gauges for Arctic sea-level reconstruction
DEFF Research Database (Denmark)
Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg
2015-01-01
and the use of an ocean circulation model to provide gridded time series of sea level. As a surrogate for satellite altimetry, we have used the Drakkar ocean model to yield the EOFs. We initially evaluate the tide gauges through empirical criteria to reject obvious outlier gauges. Subsequently, we evaluate......In this paper, we seek an appropriate selection of tide gauges for Arctic Ocean sea-level reconstruction based on a combination of empirical criteria and statistical properties (leverages). Tide gauges provide the only in situ observations of sea level prior to the altimetry era. However, tide...... for the period 1950-2010 for the Arctic Ocean, constrained by tide gauge records, using the basic approach of Church et al. (2004). A major challenge is the sparsity of both satellite and tide gauge data beyond what can be covered with interpolation, necessitating a time-variable selection of tide gauges...
Statistical properties of Fourier-based time-lag estimates
Epitropakis, A.; Papadakis, I. E.
2016-06-01
Context. The study of X-ray time-lag spectra in active galactic nuclei (AGN) is currently an active research area, since it has the potential to illuminate the physics and geometry of the innermost region (i.e. close to the putative super-massive black hole) in these objects. To obtain reliable information from these studies, the statistical properties of time-lags estimated from data must be known as accurately as possible. Aims: We investigated the statistical properties of Fourier-based time-lag estimates (i.e. based on the cross-periodogram), using evenly sampled time series with no missing points. Our aim is to provide practical "guidelines" on estimating time-lags that are minimally biased (i.e. whose mean is close to their intrinsic value) and have known errors. Methods: Our investigation is based on both analytical work and extensive numerical simulations. The latter consisted of generating artificial time series with various signal-to-noise ratios and sampling patterns/durations similar to those offered by AGN observations with present and past X-ray satellites. We also considered a range of different model time-lag spectra commonly assumed in X-ray analyses of compact accreting systems. Results: Discrete sampling, binning and finite light curve duration cause the mean of the time-lag estimates to have a smaller magnitude than their intrinsic values. Smoothing (i.e. binning over consecutive frequencies) of the cross-periodogram can add extra bias at low frequencies. The use of light curves with low signal-to-noise ratio reduces the intrinsic coherence, and can introduce a bias to the sample coherence, time-lag estimates, and their predicted error. Conclusions: Our results have direct implications for X-ray time-lag studies in AGN, but can also be applied to similar studies in other research fields. We find that: a) time-lags should be estimated at frequencies lower than ≈ 1/2 the Nyquist frequency to minimise the effects of discrete binning of the
Statistical Treatment of Low-Energy Nuclear Level Schemes
Institute of Scientific and Technical Information of China (English)
M.Gholami; M.Kildir; A.N.Behkami
2007-01-01
The level density parameter and the back shift energy E1 are determined for nuclei with A-values across the whole periodic table from fits to complete level schemes at low excitation energy near the neutron binding energies.We find that the energy back shift E1 shows complicated behavior and depends on the type of the nucleus,even-even,odd mass,and odd-odd.The spin cut-off factor has also been investigated for nuclei mentioned above.The results arecompared with the previous results and different experimental data on level densities.
Statistical properties of giant pulses from the Crab pulsar
Popov, M V
2007-01-01
We have studied the statistics of giant pulses from the Crab pulsar for the first time with particular reference to their widths. We have analyzed data collected during 3.5 hours of observations conducted with the Westerbork Synthesis Radio Telescope operated in a tied-array mode at a frequency of 1200 MHz. The PuMa pulsar backend provided voltage recording of X and Y linear polarization states in two conjugate 10 MHz bands. We restricted the time resolution to 4 microseconds to match the scattering on the interstellar inhomogeneities. In total about 18000 giant pulses (GP) were detected in full intensity with a threshold level of 6 sigma. Cumulative probability distributions (CPD) of giant pulse energies were analyzed for groups of GPs with different effective widths in the range 4 to 65 microseconds. The CPDs were found to manifest notable differences for the different GP width groups. The slope of a power-law fit to the high-energy portion of the CPDs evolves from -1.7 to -3.2 when going from the shortest ...
Intensity distribution function and statistical properties of fast radio bursts
Li, Long-Biao; Huang, Yong-Feng; Zhang, Zhi-Bin; Li, Di; Li, Bing
2017-01-01
Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are characterized by millisecond durations and Jansky-level flux densities. We carried out a statistical analysis on FRBs that have been discovered. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be , supporting their being from a cosmological origin. Their energy released in the radio band spans about two orders of magnitude, with a mean value of erg. More interestingly, although the study of FRBs is still in a very early phase, the published collection of FRBs enables us to derive a useful intensity distribution function. For the 16 non-repeating FRBs detected by the Parkes telescope and the Green Bank Telescope, the intensity distribution can be described as , where is the observed radio fluence in units of Jy ms. Here the power-law index is significantly flatter than the expected value of 2.5 for standard candles distributed homogeneously in a flat Euclidean space. Based on this intensity distribution function, the Five-hundred-meter Aperture Spherical radio Telescope (FAST) is predicted to be able to detect about five FRBs for every 1000 h of observation time.
Apparent Luminosity Function and Statistical Properties of Fast Radio Bursts
Li, LongBiao; Zhang, ZhiBin; Li, Di; Li, Bing
2016-01-01
Fast Radio Bursts (FRBs) are intense radio flashes from the sky that are astonishingly characterized by millisecond durations and Jansky-level flux densities. Only 16 FRBs have been reported in the literature till now. We carry out a statistical analysis on these events. Their mean dispersion measure, after subtracting the contribution from the interstellar medium of our Galaxy, is found to be $\\sim 655 \\; \\rm pc\\,cm^{-3}$, strongly supporting the idea that they are of cosmological origin. Their energy release in radio band spans about three orders of magnitude, with a mean value of $\\sim 6.42\\times10^{38}$ ergs. The radio energy is found to be positively correlated with the observed fluence and the dispersion measure excess, and the fluence also shows a clear positive correlation with the FRB duration. Among all these events, FRBs 010621 and 010724 seem to form a distinct group in a few plots, indicating that there may be at lease two classes of FRBs. More interestingly, although the FRB study is still in a ...
Dai, Mingwei; Ming, Jingsi; Cai, Mingxuan; Liu, Jin; Yang, Can; Wan, Xiang; Xu, Zongben
2017-09-15
Results from genome-wide association studies (GWAS) suggest that a complex phenotype is often affected by many variants with small effects, known as 'polygenicity'. Tens of thousands of samples are often required to ensure statistical power of identifying these variants with small effects. However, it is often the case that a research group can only get approval for the access to individual-level genotype data with a limited sample size (e.g. a few hundreds or thousands). Meanwhile, summary statistics generated using single-variant-based analysis are becoming publicly available. The sample sizes associated with the summary statistics datasets are usually quite large. How to make the most efficient use of existing abundant data resources largely remains an open question. In this study, we propose a statistical approach, IGESS, to increasing statistical power of identifying risk variants and improving accuracy of risk prediction by i ntegrating individual level ge notype data and s ummary s tatistics. An efficient algorithm based on variational inference is developed to handle the genome-wide analysis. Through comprehensive simulation studies, we demonstrated the advantages of IGESS over the methods which take either individual-level data or summary statistics data as input. We applied IGESS to perform integrative analysis of Crohns Disease from WTCCC and summary statistics from other studies. IGESS was able to significantly increase the statistical power of identifying risk variants and improve the risk prediction accuracy from 63.2% ( ±0.4% ) to 69.4% ( ±0.1% ) using about 240 000 variants. The IGESS software is available at https://github.com/daviddaigithub/IGESS . zbxu@xjtu.edu.cn or xwan@comp.hkbu.edu.hk or eeyang@hkbu.edu.hk. Supplementary data are available at Bioinformatics online.
Cambridge international AS and A level mathematics statistics
Porkess, Roger; Konrad, Nina
2012-01-01
This brand new series has been written for the University of Cambridge International Examinations course for AS and A Level Mathematics (9709). This title covers the requirements of S1 and S2. The authors are experienced examiners and teachers who have written extensively at this level, so have ensured all mathematical concepts are explained using language and terminology that is appropriate for students across the world. Students are provded with clear and detailed worked examples and questions from Cambridge International past papers, so they have the opportunity for plenty of essenti
Modulated two-level system: exact work statistics.
Verley, Gatien; Van den Broeck, Christian; Esposito, Massimiliano
2013-09-01
We consider an open two-level system driven by a piecewise constant periodic field and described by a rate equation with Fermi, Bose, and Arrhenius rates, respectively. We derive an analytical expression for the generating function and large deviation function of the work performed by the field and show that a work fluctuation theorem holds.
Level Statistics and Localization Transitions of Lévy Matrices.
Tarquini, E; Biroli, G; Tarzia, M
2016-01-08
This work provides a thorough study of Lévy, or heavy-tailed, random matrices (LMs). By analyzing the self-consistent equation on the probability distribution of the diagonal elements of the resolvent we establish the equation determining the localization transition and obtain the phase diagram. Using arguments based on supersymmetric field theory and Dyson Brownian motion we show that the eigenvalue statistics is the same one as of the Gaussian orthogonal ensemble in the whole delocalized phase and is Poisson-like in the localized phase. Our numerics confirm these findings, valid in the limit of infinitely large LMs, but also reveal that the characteristic scale governing finite size effects diverges much faster than a power law approaching the transition and is already very large far from it. This leads to a very wide crossover region in which the system looks as if it were in a mixed phase. Our results, together with the ones obtained previously, now provide a complete theory of Lévy matrices.
Level Statistics and Localization Transitions of Lévy Matrices
Tarquini, E.; Biroli, G.; Tarzia, M.
2016-01-01
This work provides a thorough study of Lévy, or heavy-tailed, random matrices (LMs). By analyzing the self-consistent equation on the probability distribution of the diagonal elements of the resolvent we establish the equation determining the localization transition and obtain the phase diagram. Using arguments based on supersymmetric field theory and Dyson Brownian motion we show that the eigenvalue statistics is the same one as of the Gaussian orthogonal ensemble in the whole delocalized phase and is Poisson-like in the localized phase. Our numerics confirm these findings, valid in the limit of infinitely large LMs, but also reveal that the characteristic scale governing finite size effects diverges much faster than a power law approaching the transition and is already very large far from it. This leads to a very wide crossover region in which the system looks as if it were in a mixed phase. Our results, together with the ones obtained previously, now provide a complete theory of Lévy matrices.
Links to sources of cancer-related statistics, including the Surveillance, Epidemiology and End Results (SEER) Program, SEER-Medicare datasets, cancer survivor prevalence data, and the Cancer Trends Progress Report.
STATISTICAL PROPERTIES OF LONG-RANGE CONTACTS IN GLOBULAR PROTEINS
Institute of Scientific and Technical Information of China (English)
Xiang-hong Wang; Jian-hong Ke; Mang-xiao Hu
2004-01-01
The analysis of residue-residue contacts in protein structures can shed some light on our understanding of the folding and stability of proteins. In this paper, we study the statistical properties of long-range and short-range residueresidue contacts of 91 globular proteins using CSU software and analyze the importance of long-range contacts in globular protein structure. There are many short-range and long-range contacts in globular proteins, and it is found that the average number of long-range contacts per residue is 5.63 and the percentage of residue-residue contacts which are involved in longrange ones is 59.4%. In more detail, the distribution of long-range contacts in different residue intervals is investigated and it is found that the residues occurring in the interval range of 4-10 residues apart in the sequence contribute more long-range contacts to the stability of globular protein. The number of long-range contacts per residue, which is a measure of ability to form residue-residue contacts, is also calculated for 20 different amino acid residues. It is shown that hydrophobic residues (including Leu, Val, Ile, Met, Phc, Tyr, Cys and Trp) having a large number of long-range contacts easily form long-range contacts, while the hydrophilic amino acids (including Ala, Gly, Thr, His, Glu, Gin, Asp, Asn, Lys, Ser, Arg, and Pro) form long-range contacts with more difficulty. The relationship between the Fauchere-Pliska hydrophobicity scale (FPH) and the number of short-range and long-range contacts per residue for 20 amino acid residues is also studied. An approximately linear relationship between the Fauchere-Pliska hydrophobicity scale (FPH) and the number of long-range contacts per residue CL is found and can be expressed as CiL= a + b x FPHwhere a = 5.04 and b = 1.23. These results can help us to understand the role of residue-residue contacts in globular protein structure.
P.R.E.S.S.--an R-package for exploring residual-level protein structural statistics.
Huang, Yuanyuan; Bonett, Stephen; Kloczkowski, Andrzej; Jernigan, Robert; Wu, Zhijun
2012-06-01
P.R.E.S.S. is an R-package developed to allow researchers to get access to and manipulate a large set of statistical data on protein residue-level structural properties such as residue-level virtual bond lengths, virtual bond angles, and virtual torsion angles. A large set of high-resolution protein structures is downloaded and surveyed. Their residue-level structural properties are calculated and documented. The statistical distributions and correlations of these properties can be queried and displayed. Tools are also provided for modeling and analyzing a given structure in terms of its residue-level structural properties. In particular, new tools for computing residue-level statistical potentials and displaying residue-level Ramachandran-like plots are developed for structural analysis and refinement. P.R.E.S.S. has been released in R as an open source software package, with a user-friendly GUI, accessible and executable by a public user in any R environment. P.R.E.S.S. can also be downloaded directly at http://www.math.iastate.edu/press/.
Directory of Open Access Journals (Sweden)
Waldir de Carvalho Junior
2014-06-01
Full Text Available Soil properties have an enormous impact on economic and environmental aspects of agricultural production. Quantitative relationships between soil properties and the factors that influence their variability are the basis of digital soil mapping. The predictive models of soil properties evaluated in this work are statistical (multiple linear regression-MLR and geostatistical (ordinary kriging and co-kriging. The study was conducted in the municipality of Bom Jardim, RJ, using a soil database with 208 sampling points. Predictive models were evaluated for sand, silt and clay fractions, pH in water and organic carbon at six depths according to the specifications of the consortium of digital soil mapping at the global level (GlobalSoilMap. Continuous covariates and categorical predictors were used and their contributions to the model assessed. Only the environmental covariates elevation, aspect, stream power index (SPI, soil wetness index (SWI, normalized difference vegetation index (NDVI, and b3/b2 band ratio were significantly correlated with soil properties. The predictive models had a mean coefficient of determination of 0.21. Best results were obtained with the geostatistical predictive models, where the highest coefficient of determination 0.43 was associated with sand properties between 60 to 100 cm deep. The use of a sparse data set of soil properties for digital mapping can explain only part of the spatial variation of these properties. The results may be related to the sampling density and the quantity and quality of the environmental covariates and predictive models used.
LEVEL STATISTICS AND PARITY EFFECT ON SMALL SUPERCONDUCTING SYSTEMS
Institute of Scientific and Technical Information of China (English)
CHEN ZHI-QIAN; ZHENG REN-RONG
2001-01-01
In this paper we have calculated the variations of the gap △'(0, d) and transition temperature Tc' in small metallic grains as functions of grain size (or the level spacing d between discrete electronic states) for the cases of odd and even numbers of electrons by applying the random matrix theory to the mean field theory. We find the presence of enhancement of superconductivity and critical dc, where the superconductivity of small grains breaks down. This agrees with Anderson's prediction (1959 J. Phys. Chem. Solids 11 28). We find that in the grains, as the size is lowered,the transition temperature Tc' decreases and A'(O, d)/kBTc' ≤πe-γ in odd numbers of electrons, and for Gaussian orthogonal and unitary ensembles in some regimes △'(0, d)/kBTc' ＞πe-γ in even numbers of electrons.
Statistical selection of tide gauges for Arctic sea-level reconstruction
Svendsen, Peter Limkilde; Andersen, Ole Baltazar; Nielsen, Allan Aasbjerg
2015-05-01
In this paper, we seek an appropriate selection of tide gauges for Arctic Ocean sea-level reconstruction based on a combination of empirical criteria and statistical properties (leverages). Tide gauges provide the only in situ observations of sea level prior to the altimetry era. However, tide gauges are sparse, of questionable quality, and occasionally contradictory in their sea-level estimates. Therefore, it is essential to select the gauges very carefully. In this study, we have established a reconstruction based on empirical orthogonal functions (EOFs) of sea-level variations for the period 1950-2010 for the Arctic Ocean, constrained by tide gauge records, using the basic approach of Church et al. (2004). A major challenge is the sparsity of both satellite and tide gauge data beyond what can be covered with interpolation, necessitating a time-variable selection of tide gauges and the use of an ocean circulation model to provide gridded time series of sea level. As a surrogate for satellite altimetry, we have used the Drakkar ocean model to yield the EOFs. We initially evaluate the tide gauges through empirical criteria to reject obvious outlier gauges. Subsequently, we evaluate the "influence" of each Arctic tide gauge on the EOF-based reconstruction through the use of statistical leverage and use this as an indication in selecting appropriate tide gauges, in order to procedurally identify poor-quality data while still including as much data as possible. To accommodate sparse or contradictory tide gauge data, careful preprocessing and regularization of the reconstruction model are found to make a substantial difference to the quality of the reconstruction and the ability to select appropriate tide gauges for a reliable reconstruction. This is an especially important consideration for the Arctic, given the limited amount of data available. Thus, such a tide gauge selection study can be considered a precondition for further studies of Arctic sea-level
Gontscharuk, Veronika; Landwehr, Sandra; Finner, Helmut
2015-01-01
The higher criticism (HC) statistic, which can be seen as a normalized version of the famous Kolmogorov-Smirnov statistic, has a long history, dating back to the mid seventies. Originally, HC statistics were used in connection with goodness of fit (GOF) tests but they recently gained some attention in the context of testing the global null hypothesis in high dimensional data. The continuing interest for HC seems to be inspired by a series of nice asymptotic properties related to this statistic. For example, unlike Kolmogorov-Smirnov tests, GOF tests based on the HC statistic are known to be asymptotically sensitive in the moderate tails, hence it is favorably applied for detecting the presence of signals in sparse mixture models. However, some questions around the asymptotic behavior of the HC statistic are still open. We focus on two of them, namely, why a specific intermediate range is crucial for GOF tests based on the HC statistic and why the convergence of the HC distribution to the limiting one is extremely slow. Moreover, the inconsistency in the asymptotic and finite behavior of the HC statistic prompts us to provide a new HC test that has better finite properties than the original HC test while showing the same asymptotics. This test is motivated by the asymptotic behavior of the so-called local levels related to the original HC test. By means of numerical calculations and simulations we show that the new HC test is typically more powerful than the original HC test in normal mixture models.
Some statistical properties of gene expression clustering for array data
DEFF Research Database (Denmark)
Abreu, G C G; Pinheiro, A; Drummond, R D
2010-01-01
DNA array data without a corresponding statistical error measure. We propose an easy-to-implement and simple-to-use technique that uses bootstrap re-sampling to evaluate the statistical error of the nodes provided by SOM-based clustering. Comparisons between SOM and parametric clustering are presented...... for simulated as well as for two real data sets. We also implement a bootstrap-based pre-processing procedure for SOM, that improves the false discovery ratio of differentially expressed genes. Code in Matlab is freely available, as well as some supplementary material, at the following address: https...
Spoden, Christian; Fleischer, Jens; Leutner, Detlev
2014-01-01
Testing hypotheses on a respondent's individual fit under the Rasch model requires knowledge of the distributional properties of a person fit statistic. We argue that the Rasch Sampler (Verhelst, 2008), a Markov chain Monte Carlo algorithm for sampling binary data matrices from a uniform distribution, can be applied for simulating the distribution of person fit statistics with the Rasch model in the same way as it used to test for other forms of misfit. Results from two simulation studies are presented which compare the approach to the original person fit statistics based on normalization formulas. Simulation 1 shows the new approach to hold the expected Type I error rates while the normalized statistics deviate from the nominal alpha-level. In Simulation 2 the power of the new approach was found to be approximately the same or higher than for the normalized statistics under most conditions.
Statistical properties of SGR 1806-20 bursts
Göğüş, E.; Woods, P.M.; Kouveliotou, C.; van Paradijs, J.; Briggs, M.S.; Duncan, R.C.; Thompson, C.
2000-01-01
We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary Explorer. We find that the fluence d
Statistical properties of SGR 1900+14 bursts
Göğüş, E.; Woods, P.M.; Kouveliotou, C.; van Paradijs, J.; Briggs, M.S.; Duncan, R.C.; Thompson, C.
1999-01-01
We study the statistics of soft gamma repeater (SGR) bursts using a database of 187 events detected with BATSE and 837 events detected with the Rossi X-Ray Timing Explorer Proportional Counter Array; all events are from SGR 1900+14 during its 1998-1999 active phase. We find that the fluence or energ
Universal and nonuniversal level statistics in a chaotic quantum spin chain.
Pineda, Carlos; Prosen, Tomaz
2007-12-01
We study the level statistics of an interacting multiqubit system, namely the kicked Ising spin chain, in the regime of quantum chaos. Long range quasienergy level statistics show effects analogous to the ones observed in semiclassical systems due to the presence of short classical periodic orbits, while short range level statistics display perfect statistical agreement with random matrix theory. Even though our system possesses no classical limit, our results suggest existence of an important nonuniversal system specific behavior at short time scale, which clearly goes beyond finite size effects in random matrix theory.
Some statistical properties of gene expression clustering for array data
DEFF Research Database (Denmark)
Abreu, G C G; Pinheiro, A; Drummond, R D;
2010-01-01
DNA array data without a corresponding statistical error measure. We propose an easy-to-implement and simple-to-use technique that uses bootstrap re-sampling to evaluate the statistical error of the nodes provided by SOM-based clustering. Comparisons between SOM and parametric clustering are presented......DNA arrays have been a rich source of data for the study of genomic expression of a wide variety of biological systems. Gene clustering is one of the paradigms quite used to assess the significance of a gene (or group of genes). However, most of the gene clustering techniques are applied to c...... for simulated as well as for two real data sets. We also implement a bootstrap-based pre-processing procedure for SOM, that improves the false discovery ratio of differentially expressed genes. Code in Matlab is freely available, as well as some supplementary material, at the following address: https...
Langers, Dave R. M.
2010-01-01
This report presents and validates a method for the group-level statistical assessment of independent component analysis (ICA) outcomes. The method is based on a matching of individual component maps to corresponding aggregate maps that are obtained from concatenated data. Group-level statistics are
A new method of studying the statistical properties of speckle phase
Institute of Scientific and Technical Information of China (English)
Qiankai Wang
2009-01-01
A new theoretical method with generality is proposed to study the statistical properties of the speckle phase. The general expression of the standard deviation of the speckle phase about the first-order statistics is derived according to the relation between the phase and the complex speckle amplitude. The statistical properties of the speckle phase have been studied in the diffraction fields with this new theoretical method.
Properties of frequentist confidence levels derivatives
Martínez, Miriam Lucio; Dettori, Francesco
2016-01-01
In high energy physics, results from searches for new particles or rare processes are often reported using a modified frequentist approach, known as $\\rm{CL_s}$ method. In this paper, we study the properties of the derivatives of $\\rm{CL_s}$ and $\\rm{CL_{s+b}}$ as signal strength estimators if the confidence levels are interpreted as credible intervals. Our approach allows obtaining best fit points and $\\chi^2$ functions which can be used for phenomenology studies. In addition, this approach can be used to incorporate $\\rm{CL_s}$ results into Bayesian combinations.
Statistical Properties of Gamma-Ray Burst Host Galaxies
Indian Academy of Sciences (India)
Jie-Min Chen; Jin Zhang; Lan-Wei Jia; En-Wei Liang
2014-09-01
A statistical analysis of gamma-ray burst host galaxies is presented and a clear metallicity-stellar mass relation is found in our sample. A trend that a more massive host galaxy tends to have a higher star-formation rate is also found. No correlation is found between V and H. GRB host galaxies at a higher redshift also tend to have a higher star formation rate, however, even in the same redshift, the star formation rate may vary for three orders of magnitude.
Statistical analysis of the metrological properties of float glass
Yates, Brian W.; Duffy, Alan M.
2008-08-01
The radius of curvature, slope error, surface roughness and associated height distribution and power spectral density of uncoated commercial float glass samples have been measured in our Canadian Light Source Optical Metrology Facility, using our Micromap-570 surface profiler and long trace profilometer. The statistical differences in these parameters have been investigated between the tin and air sides of float glass. The effect of soaking the float glass in sulfuric acid to try to dissolve the tin contamination has also been investigated, and untreated and post-treatment surface roughness measurements compared. We report the results of our studies on these float glass samples.
The Statistical Properties of Hedge Fund Index Returns
Chris Brooks; Harry M. Kat
2001-01-01
he monthly return distributions of many hedge fund indices exhibit highly unusual skewness and kurtosis properties as well as first-order serial correlation. This has important consequences for investors. We demonstrate that although hedge fund indices are highly attractive in mean-variance terms, this is much less the case when skewness, kurtosis and autocorrelation are taken into account. Sharpe Ratios will substantially overestimate the true risk-return performance of (portfolios containin...
Statistical Properties of Antenna Impedance in an Electrically Large Cavity
Energy Technology Data Exchange (ETDEWEB)
WARNE,LARRY K.; LEE,KELVIN S.H.; HUDSON,H. GERALD; JOHNSON,WILLIAM A.; JORGENSON,ROY E.; STRONACH,STEPHEN L.
2000-12-13
This paper presents models and measurements of antenna input impedance in resonant cavities at high frequencies.The behavior of input impedance is useful in determining the transmission and reception characteristics of an antenna (as well as the transmission characteristics of certain apertures). Results are presented for both the case where the cavity is undermoded (modes with separate and discrete spectra) as well as the over moded case (modes with overlapping spectra). A modal series is constructed and analyzed to determine the impedance statistical distribution. Both electrically small as well as electrically longer resonant and wall mounted antennas are analyzed. Measurements in a large mode stirred chamber cavity are compared with calculations. Finally a method based on power arguments is given, yielding simple formulas for the impedance distribution.
Statistical properties of Charney-Hasegawa-Mima zonal flows
Energy Technology Data Exchange (ETDEWEB)
Anderson, Johan, E-mail: anderson.johan@gmail.com [Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Göteborg (Sweden); Botha, G. J. J. [Department of Mathematics and Information Sciences, Northumbria University, Newcastle Upon Tyne NE1 8ST (United Kingdom)
2015-05-15
A theoretical interpretation of numerically generated probability density functions (PDFs) of intermittent plasma transport events in unforced zonal flows is provided within the Charney-Hasegawa-Mima (CHM) model. The governing equation is solved numerically with various prescribed density gradients that are designed to produce different configurations of parallel and anti-parallel streams. Long-lasting vortices form whose flow is governed by the zonal streams. It is found that the numerically generated PDFs can be matched with analytical predictions of PDFs based on the instanton method by removing the autocorrelations from the time series. In many instances, the statistics generated by the CHM dynamics relaxes to Gaussian distributions for both the electrostatic and vorticity perturbations, whereas in areas with strong nonlinear interactions it is found that the PDFs are exponentially distributed.
Statistical Model Checking of Rich Models and Properties
DEFF Research Database (Denmark)
Poulsen, Danny Bøgsted
in undecidability issues for the traditional model checking approaches. Statistical model checking has proven itself a valuable supplement to model checking and this thesis is concerned with extending this software validation technique to stochastic hybrid systems. The thesis consists of two parts: the first part......Software is in increasing fashion embedded within safety- and business critical processes of society. Errors in these embedded systems can lead to human casualties or severe monetary loss. Model checking technology has proven formal methods capable of finding and correcting errors in software....... However, software is approaching the boundary in terms of the complexity and size that model checking can handle. Furthermore, software systems are nowadays more frequently interacting with their environment hence accurately modelling such systems requires modelling the environment as well - resulting...
Statistical properties of cloud lifecycles in cloud-resolving models
Directory of Open Access Journals (Sweden)
R. S. Plant
2008-12-01
Full Text Available A new technique is described for the analysis of cloud-resolving model simulations, which allows one to investigate the statistics of the lifecycles of cumulus clouds. Clouds are tracked from timestep-to-timestep within the model run. This allows for a very simple method of tracking, but one which is both comprehensive and robust. An approach for handling cloud splits and mergers is described which allows clouds with simple and complicated time histories to be compared within a single framework. This is found to be important for the analysis of an idealized simulation of radiative-convective equilibrium, in which the moist, buoyant, updrafts (i.e., the convective cores were tracked. Around half of all such cores were subject to splits and mergers during their lifecycles. For cores without any such events, the average lifetime is 30 min, but events can lengthen the typical lifetime considerably.
Statistics of physical properties of dark matter clusters
Energy Technology Data Exchange (ETDEWEB)
Shaw, Laurie; /Cambridge U., Inst. of Astron.; Weller, Jochen; /Fermilab /University Coll. London; Ostriker, Jeremiah P.; /Cambridge U., Inst. of Astron. /Princeton U.; Bode, Paul; /Princeton U. Observ.
2005-09-01
We have identified over 2000 well resolved cluster halos, and also their associated bound subhalos, from the output of 1024{sup 3} particle cosmological N-body simulation (of box size 320h{sup -1}Mpc and softening length 3.2h{sup -1}kpc). We present an algorithm to identify those halos still in the process of relaxing into dynamical equilibrium, and a detailed analysis of the integral and internal physical properties for all the halos in our sample. The majority are prolate, and tend to rotate around their minor principle axis. We find there to be no correlation between the spin and virial mass of the clusters halos and that the higher mass halos are less dynamically relaxed and have a lower concentration. Additionally, the orbital angular momentum of the substructure is typically well aligned with the rotational angular momentum of the ''host'' halo. There is also evidence of the transfer of angular momentum from subhalos to their host. Overall, we find that measured halo properties are often significantly influenced by the fraction of mass contained within substructure. Dimensionless properties do depend weakly on the ratio of halo mass (M{sub h}) to our characteristic mass scale (M{sub *} = 8 x 10{sup 14}h{sup -1}M{sub {circle_dot}}). This lack of self-similarity is in the expected sense in that, for example, ''old halos'' with M{sub h}/M{sub *} << 1 have less substructure than ''young halos'' with M{sub h}/M{sub *} >> 1.
Statistical properties of position-dependent ball-passing networks in football games
Narizuka, Takuma; Yamazaki, Yoshihiro
2013-01-01
Statistical properties of position-dependent ball-passing networks in real football games are examined. We find that the networks have the small-world property, and their degree distributions are fitted well by a truncated gamma distribution function. In order to reproduce these properties of networks, a model based on a Markov chain is proposed.
Energy Level Statistics of SO(5) Limit of Super-symmetry U(6/4) in Interacting Boson-Fermion Model
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
We study the energy level statistics of the SO(5) limit of super-symmetry U(6/4) in odd-A nucleus using the interacting boson-fermion model. The nearest neighbor spacing distribution (NSD) and the spectral rigidity (△3)are investigated, and the factors that affect the properties of level statistics are also discussed. The results show that the boson number N is a dominant factor. If N is small, both the interaction strengths of subgroups SOB(5) and SOBF(5)and the spin play important roles in the energy level statistics, however, along with the increase of N, the statistics distribution would tend to be in Poisson form.
奇奇核86Nb的能谱统计%Level Statistics of Odd-Odd Nucleon 86Nb
Institute of Scientific and Technical Information of China (English)
程南璞; 郑仁蓉; 朱顺泉
2001-01-01
The energy levels of odd-odd nucleon 86 N b are calculated by using the axially symmetric rotor plus quasiparticle model. Its emphasis is to study the statistical properties of the nearest-neighbor spa cings (NNS) and the spectral rigidity (Δ3) under different s pins. And the factors that affect the properties of level statistics are also in vestigated.%用粒子-转子理论模型计算奇奇核86Nb低 自旋下的 能谱，研究了不同自旋下能谱最近邻能级间距分布(NNS)和能谱刚性度 (Δ3)的特点，并就影响能谱统计特征的因素进行了分析.
Statistical Properties of 6.7 GHz Methanol Maser Sources
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
We present a statistical analysis of 482 6.7 GHz methanol maser sourcesfrom the available literature, on their maser emission and the characteristics oftheir associated infrared sources. On the color-color diagram, more than 70% ofthe objects fall within a very small region (0.57 ≤ [25 - 12] ≤ 1.30 and 1.30 ≤[60 - 12] ≤ 2.50). This suggests that 6.7 GHz methanol maser emission occurs onlywithin a very short evolutionary phase during the earliest stage of star formation.The velocity ranges of the masers belong to two main groups: one from 1 to 10km s-1, and one from about 11 to 20 km s-1. These velocity ranges indicate thatthe masers are probably associated with both disks and outflows. The correlationsbetween the maser and infrared flux densities, and between the maser and infraredluminosities, suggest that far-infrared radiation is a possible pumping mechanismfor the masers which most probably originate from some outer molecular envelopesor disks.
Modular properties of Eisenstein series and statistical physics
Dowker, J S
2008-01-01
The temperature inversion properties of the internal energy, E, on odd spheres, and its derivatives, together with their expression in elliptic terms, as expounded in previous papers, are extended to the integrals of E, thence making contact with the theory of modular forms with rational period functions. I point out that the period functions of (holomorphic) Eisenstein series computed by Zagier were already available since the time of Ramanujan and I give a rederivation by contour integration. Removing both the Planck and Casimir terms gives a fully subtracted form of the series which allows a more elegant and compact treatment. I expound the relation to Eichler cohomology cocycles and also rewrite the theory in a distributional, Green function way. Some historical and technical developments of the Selberg--Chowla formula are presented, and it is suggested that this be renamed the Epstein--Kober formula. On another point of historical justice, the work of Koshliakov on Dirichlet series is reprised. A represe...
A study of statistics anxiety levels of graduate dental hygiene students.
Welch, Paul S; Jacks, Mary E; Smiley, Lynn A; Walden, Carolyn E; Clark, William D; Nguyen, Carol A
2015-02-01
In light of increased emphasis on evidence-based practice in the profession of dental hygiene, it is important that today's dental hygienist comprehend statistical measures to fully understand research articles, and thereby apply scientific evidence to practice. Therefore, the purpose of this study was to investigate statistics anxiety among graduate dental hygiene students in the U.S. A web-based self-report, anonymous survey was emailed to directors of 17 MSDH programs in the U.S. with a request to distribute to graduate students. The survey collected data on statistics anxiety, sociodemographic characteristics and evidence-based practice. Statistic anxiety was assessed using the Statistical Anxiety Rating Scale. Study significance level was α=0.05. Only 8 of the 17 invited programs participated in the study. Statistical Anxiety Rating Scale data revealed graduate dental hygiene students experience low to moderate levels of statistics anxiety. Specifically, the level of anxiety on the Interpretation Anxiety factor indicated this population could struggle with making sense of scientific research. A decisive majority (92%) of students indicated statistics is essential for evidence-based practice and should be a required course for all dental hygienists. This study served to identify statistics anxiety in a previously unexplored population. The findings should be useful in both theory building and in practical applications. Furthermore, the results can be used to direct future research. Copyright © 2015 The American Dental Hygienists’ Association.
The Effect of Project Based Learning on the Statistical Literacy Levels of Student 8th Grade
Koparan, Timur; Güven, Bülent
2014-01-01
This study examines the effect of project based learning on 8th grade students' statistical literacy levels. A performance test was developed for this aim. Quasi-experimental research model was used in this article. In this context, the statistics were taught with traditional method in the control group and it was taught using project based…
Statistical evaluation of the mechanical properties of high-volume class F fly ash concretes
Yoon, Seyoon
2014-03-01
High-Volume Fly Ash (HVFA) concretes are seen by many as a feasible solution for sustainable, low embodied carbon construction. At the moment, fly ash is classified as a waste by-product, primarily of thermal power stations. In this paper the authors experimentally and statistically investigated the effects of mix-design factors on the mechanical properties of high-volume class F fly ash concretes. A total of 240 and 32 samples were produced and tested in the laboratory to measure compressive strength and Young\\'s modulus respectively. Applicability of the CEB-FIP (Comite Euro-international du Béton - Fédération Internationale de la Précontrainte) and ACI (American Concrete Institute) Building Model Code (Thomas, 2010; ACI Committee 209, 1982) [1,2] to the experimentally-derived mechanical property data for HVFA concretes was established. Furthermore, using multiple linear regression analysis, Mean Squared Residuals (MSRs) were obtained to determine whether a weight- or volume-based mix proportion is better to predict the mechanical properties of HVFA concrete. The significance levels of the design factors, which indicate how significantly the factors affect the HVFA concrete\\'s mechanical properties, were determined using analysis of variance (ANOVA) tests. The results show that a weight-based mix proportion is a slightly better predictor of mechanical properties than volume-based one. The significance level of fly ash substitution rate was higher than that of w/b ratio initially but reduced over time. © 2014 Elsevier Ltd. All rights reserved.
The COpernicus COmplexio: Statistical Properties of Warm Dark Matter Haloes
Bose, Sownak; Frenk, Carlos S; Jenkins, Adrian; Lovell, Mark R; Helly, John C; Li, Baojiu
2015-01-01
The recent detection of a 3.5 keV X-ray line from the centres of galaxies and clusters by Bulbul et al. (2014a) and Boyarsky et al. (2014a) has been interpreted as emission from the decay of 7 keV sterile neutrinos which could make up the (warm) dark matter (WDM). As part of the COpernicus COmplexio (COCO) programme, we investigate the properties of dark matter haloes formed in a high-resolution cosmological $N$-body simulation from initial conditions similar to those expected in a universe in which the dark matter consists of 7 keV sterile neutrinos. This simulation and its cold dark matter (CDM) counterpart have $\\sim13.4$bn particles, each of mass $\\sim 10^5\\, h^{-1} M_\\odot$, providing detailed information about halo structure and evolution down to dwarf galaxy mass scales. Non-linear structure formation on small scales ($M_{200}\\, \\leq\\, 2 \\times 10^9~h^{-1}\\,M_\\odot$) begins slightly later in COCO-Warm than in COCO-Cold. The halo mass function at the present day in the WDM model begins to drop below its...
Statistical Properties of Car Following: Theory and Driving Simulator Experiments
Ando, Hiromasa; Zgonnikov, Arkady; Saito, Yoshiaki
2015-01-01
A fair simple car driving simulator was created based on the open source engine TORCS and used in car-following experiments aimed at studying the basic features of human behavior in car driving. Four subjects with different skill in driving real cars participated in these experiments. The subjects were instructed to drive a car without overtaking and losing sight of a lead car driven by computer at a fixed speed. Based on the collected data the distributions of the headway distance, the car velocity, acceleration, and jerk are constructed and compared with the available experimental data for the real traffic flow. A new model for the car-following is proposed to capture the found properties. As the main result, we draw a conclusion that human actions in car driving should be categorized as generalized intermittent control with noise-driven activation. Besides, we hypothesize that the car jerk together with the car acceleration are additional phase variables required for describing the dynamics of car motion g...
Levels and properties of map perception
Directory of Open Access Journals (Sweden)
Żyszkowska Wiesława
2017-03-01
Full Text Available Map perception consists of numerous processes of information processing, taking place almost simultaneously at different levels and stages which makes it conditioned by many factors. In the article, a review of processes related to the perception of a map as well as levels and properties of perception which impact its course and the nature of information obtained from a map is presented. The most important process constituting the basis of a map perception is a visual search (eye movement. However, as stated based on the studies, the process is individual depending on the purpose of map perception and it may be guided by its image (visual search guidance or by the knowledge of users (cognitive search guidance. Perception can take place according to various schemes – “local-to-global” or “global-to-local”, or in accordance with the guided search theory. Perception is divided into three processes: perceiving, distinguishing and identifying, which constitute the basis to interpret and understand a map. They are related to various degrees of intellectual involvement of the user and to various levels of questions concerning the relations between signs and their content. Identification involves referring a sign to its explanation in the legend. Interpretation means transformation of the initial information collected from the map into derivative information in which two basic types of understanding take place: deductive and inductive. Identification of geographical space objects on the map and the interpretation of its content constitute the basis to introduce information into memory structures. In the brain a resource of information is generated called geographic knowledge or spatial representation (mental map which may have a double nature – verbal or pictorial. An important feature of mental maps is organization of spatial information into hierarchical structures, e.g. grouping towns into regions as well as deformation of spatial
On statistical properties of sets fulfilling rolling-type conditions
Cuevas, Antonio; Pateiro-López, Beatriz
2011-01-01
Motivated by set estimation problems, we consider three closely related shape conditions for compact sets: positive reach, r-convexity and rolling condition. First, the relations between these shape conditions are analyzed. Second, a result of "full consistency" (i.e., consistency with respect to the usual set distances, plus boundary Hausdorff-convergence) is obtained for the estimation of sets fulfilling a rolling condition. Third, the class of uniformly bounded compact sets whose reach is not smaller than a given constant r is shown to be a P-uniformity class (in Billingsley and Tops{\\o}e's (1967) sense) and, in particular, a Glivenko-Cantelli class. Fourth, under broad conditions, the r-convex hull of the sample is proved to be a fully consistent estimator of an r-convex support in the two-dimensional case. Moreover, its boundary length is shown to converge (a.s.) to that of the underlying support. Fifth, the above results are applied to get new consistency statements for level set estimators based on the...
Institute of Scientific and Technical Information of China (English)
Xiao Gang; Wang Shu
2006-01-01
IHS (Intensity, Hue and Saturation) transform is one of the most commonly used fusion algorithm. But the matching error causes spectral distortion and degradation in processing of image fusion with IHS method. A study on IHS fusion indicates that the color distortion can't be avoided. Meanwhile, the statistical property of wavelet coefficient with wavelet decomposition reflects those significant features, such as edges, lines and regions. So, a united optimal fusion method, which uses the statistical property and IHS transform on pixel and feature levels, is proposed. That is, the high frequency of intensity component I is fused on feature level with multi-resolution wavelet in IHS space. And the low frequency of intensity component I is fused on pixel level with optimal weight coefficients. Spectral information and spatial resolution are two performance indexes of optimal weight coefficients. Experiment results with QuickBird data of Shanghai show that it is a practical and effective method.
Energy Technology Data Exchange (ETDEWEB)
Hasegawa, N.; Nishikawa, Y.; Inaba, K. [Gifu University, Gifu (Japan). Faculty of Engineering; Fukuyama, K. [Gifu Prefectural Police Headquarters, Gifu (Japan)
1995-09-15
Rotating bending fatigue tests of smooth specimens were carried out at room temperature on a pearlitic ductile cast iron (PDI) and austempered ductile cast iron (ADI). No significant difference due to sampling position from cast blocks in both materials was found in fatigue limit and fatigue life distribution. Then, the statistical fatigue properties of ferritic (FDI), ferritic/pearlitic (FPDI), pearlitic and austempered ductile cast irons were investigated. The fatigue life distributions of all ductile irons were well represented by the three parameter Weibull distribution modified by the saturated probability of failure. The shape parameters of FDI, FPDI and PDI were in proportion to {sigma}/{sigma}w independent on micro structure, while the shape parameters of both stress levels in ADI were smaller than unity. The fatigue strength of ADI was highest, but the scatter of fatigue life was largest among the all cast irons. 13 refs., 15 figs., 7 tabs.
Statistical image properties of print advertisements, visual artworks and images of architecture
Directory of Open Access Journals (Sweden)
Julia eBraun
2013-11-01
Full Text Available Most visual advertisements are designed to attract attention, often by inducing a pleasant impression in human observers. Accordingly, results from brain imaging studies show that advertisements can activate the brain’s reward circuitry, which is also involved in the perception of other visually pleasing images, such as artworks. At the image level, large subsets of artworks are characterized by specific statistical image properties, such as a high self-similarity and intermediate complexity. Moreover, some image properties are distributed uniformly across orientations in the artworks (low anisotropy. In the present study, we asked whether images of advertisements share these properties. To answer this question, subsets of different types of advertisements (single-product print advertisements, supermarket and department store leaflets, magazine covers and show windows were analyzed using computer vision algorithms and compared to other types of images (photographs of simple objects, faces, large-vista natural scenes and branches. We show that, on average, images of advertisements and artworks share a similar degree of complexity (fractal dimension and self-similarity, as well as similarities in the Fourier spectrum. However, images of advertisements are more anisotropic than artworks. Values for single-product advertisements resemble each other, independent of the type of product promoted (cars, cosmetics, fashion or other products. For comparison, we studied images of architecture as another type of visually pleasing stimuli and obtained comparable results. These findings support the general idea that, on average, man-made visually pleasing images are characterized by specific patterns of higher-order (global image properties that distinguish them from other types of images. Whether these properties are necessary or sufficient to induce aesthetic perception and how they correlate with brain activation upon viewing advertisements remains to be
Statistical image properties of print advertisements, visual artworks and images of architecture.
Braun, Julia; Amirshahi, Seyed A; Denzler, Joachim; Redies, Christoph
2013-01-01
Most visual advertisements are designed to attract attention, often by inducing a pleasant impression in human observers. Accordingly, results from brain imaging studies show that advertisements can activate the brain's reward circuitry, which is also involved in the perception of other visually pleasing images, such as artworks. At the image level, large subsets of artworks are characterized by specific statistical image properties, such as a high self-similarity and intermediate complexity. Moreover, some image properties are distributed uniformly across orientations in the artworks (low anisotropy). In the present study, we asked whether images of advertisements share these properties. To answer this question, subsets of different types of advertisements (single-product print advertisements, supermarket and department store leaflets, magazine covers and show windows) were analyzed using computer vision algorithms and compared to other types of images (photographs of simple objects, faces, large-vista natural scenes and branches). We show that, on average, images of advertisements and artworks share a similar degree of complexity (fractal dimension) and self-similarity, as well as similarities in the Fourier spectrum. However, images of advertisements are more anisotropic than artworks. Values for single-product advertisements resemble each other, independent of the type of product promoted (cars, cosmetics, fashion or other products). For comparison, we studied images of architecture as another type of visually pleasing stimuli and obtained comparable results. These findings support the general idea that, on average, man-made visually pleasing images are characterized by specific patterns of higher-order (global) image properties that distinguish them from other types of images. Whether these properties are necessary or sufficient to induce aesthetic perception and how they correlate with brain activation upon viewing advertisements remains to be investigated.
Wallace, G. R.; Weathers, G. D.; Graf, E. R.
1973-01-01
The statistics of filtered pseudorandom digital sequences called hybrid-sum sequences, formed from the modulo-two sum of several maximum-length sequences, are analyzed. The results indicate that a relation exists between the statistics of the filtered sequence and the characteristic polynomials of the component maximum length sequences. An analysis procedure is developed for identifying a large group of sequences with good statistical properties for applications requiring the generation of analog pseudorandom noise. By use of the analysis approach, the filtering process is approximated by the convolution of the sequence with a sum of unit step functions. A parameter reflecting the overall statistical properties of filtered pseudorandom sequences is derived. This parameter is called the statistical quality factor. A computer algorithm to calculate the statistical quality factor for the filtered sequences is presented, and the results for two examples of sequence combinations are included. The analysis reveals that the statistics of the signals generated with the hybrid-sum generator are potentially superior to the statistics of signals generated with maximum-length generators. Furthermore, fewer calculations are required to evaluate the statistics of a large group of hybrid-sum generators than are required to evaluate the statistics of the same size group of approximately equivalent maximum-length sequences.
Vibrational energy transport in molecules and the statistical properties of vibrational modes
Pandey, Hari Datt; Leitner, David M.
2017-01-01
Statistical properties of the eigenmodes computed for two molecules, dodecane and perfluorododecane, are examined and compared with predictions of random matrix theory. The eigenmode statistics of the heat carrying modes of perfluorododecane correspond to Porter-Thomas statistics, whereas those for dodecane do not. Vibrational energy transport in the two molecules is also computed and found to be diffusive in perfluorododecane but not in dodecane, consistent with recent experiments. The correspondence between eigenmode statistics and vibrational energy transport dynamics in molecules as well as thermalization in molecules are discussed.
A social network's changing statistical properties and the quality of human innovation
Uzzi, Brian
2008-06-01
We examined the entire network of creative artists that made Broadway musicals, in the post-War period, a collaboration network of international acclaim and influence, with an eye to investigating how the network's structural features condition the relationship between individual artistic talent and the success of their musicals. Our findings show that some of the evolving topographical qualities of degree distributions, path lengths and assortativity are relatively stable with time even as collaboration patterns shift, which suggests their changes are only minimally associated with the ebb and flux of the success of new productions. In contrast, the clustering coefficient changed substantially over time and we found that it had a nonlinear association with the production of financially and artistically successful shows. When the clustering coefficient ratio is low or high, the financial and artistic success of the industry is low, while an intermediate level of clustering is associated with successful shows. We supported these findings with sociological theory on the relationship between social structure and collaboration and with tests of statistical inference. Our discussion focuses on connecting the statistical properties of social networks to their performance and the performance of the actors embedded within them.
Blind estimation of statistical properties of non-stationary random variables
Mansour, Ali; Mesleh, Raed; Aggoune, el-Hadi M.
2014-12-01
To identify or equalize wireless transmission channels, or alternatively to evaluate the performance of many wireless communication algorithms, coefficients or statistical properties of the used transmission channels are often assumed to be known or can be estimated at the receiver end. For most of the proposed algorithms, the knowledge of transmission channel statistical properties is essential to detect signals and retrieve data. To the best of our knowledge, most proposed approaches assume that transmission channels are static and can be modeled by stationary random variables (uniform, Gaussian, exponential, Weilbul, Rayleigh, etc.). In the majority of sensor networks or cellular systems applications, transmitters and/or receivers are in motion. Therefore, the validity of static transmission channels and the underlying assumptions may not be valid. In this case, coefficients and statistical properties change and therefore the stationary model falls short of making an accurate representation. In order to estimate the statistical properties (represented by the high-order statistics and probability density function, PDF) of dynamic channels, we firstly assume that the dynamic channels can be modeled by short-term stationary but long-term non-stationary random variable (RV), i.e., the RVs are stationary within unknown successive periods but they may suddenly change their statistical properties between two successive periods. Therefore, this manuscript proposes an algorithm to detect the transition phases of non-stationary random variables and introduces an indicator based on high-order statistics for non-stationary transmission which can be used to alter channel properties and initiate the estimation process. Additionally, PDF estimators based on kernel functions are also developed. The first part of the manuscript provides a brief introduction for unbiased estimators of the second and fourth-order cumulants. Then, the non-stationary indicators are formulated
Statistical properties of solar flares and coronal mass ejections through the solar cycle
Energy Technology Data Exchange (ETDEWEB)
Telloni, Daniele; Antonucci, Ester [INAF-Astrophysical Observatory of Torino, Via Osservatorio 20, 10025 Pino Torinese (Italy); Carbone, Vincenzo [University of Calabria, Department of Physics, Ponte P. Bucci Cubo 31C, 87036 Rende (Italy); CNR-Institute for Chemical-Physical Processes, Ponte P. Bucci Cubo 33B, 87036 Rende (Italy); Lepreti, Fabio [University of Calabria, Department of Physics, Ponte P. Bucci Cubo 31C, 87036 Rende (Italy)
2016-03-25
Waiting Time Distributions (WTDs) of solar flares are investigated all through the solar cycle. The same approach applied to Coronal Mass Ejections (CMEs) in a previous work is considered here for flare occurrence. Our analysis reveals that flares and CMEs share some common statistical properties, which result dependent on the level of solar activity. Both flares and CMEs seem to independently occur during minimum solar activity phases, whilst their WTDs significantly deviate from a Poisson function at solar maximum, thus suggesting that these events are correlated. The characteristics of WTDs are constrained by the physical processes generating those eruptions associated with flares and CMEs. A scenario may be drawn in which different mechanisms are actively at work during different phases of the solar cycle. Stochastic processes, most likely related to random magnetic reconnections of the field lines, seem to play a key role during solar minimum periods. On the other hand, persistent processes, like sympathetic eruptions associated to the variability of the photospheric magnetism, are suggested to dominate during periods of high solar activity. Moreover, despite the similar statistical properties shown by flares and CMEs, as it was mentioned above, their WTDs appear different in some aspects. During solar minimum periods, the flare occurrence randomness seems to be more evident than for CMEs. Those persistent mechanisms generating interdependent events during maximum periods of solar activity can be suggested to play a more important role for CMEs than for flares, thus mitigating the competitive action of the random processes, which seem instead strong enough to weaken the correlations among flare event occurrence during solar minimum periods. However, it cannot be excluded that the physical processes at the basis of the origin of the temporal correlation between solar events are different for flares and CMEs, or that, more likely, more sophisticated effects are
Energy Technology Data Exchange (ETDEWEB)
Huenicke, B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Kuestenforschung
2008-11-06
This study aims at the estimation of the impact of different atmospheric factors on the past sealevel variations (up to 200 years) in the Baltic Sea by statistically analysing the relationship between Baltic Sea level records and observational and proxy-based reconstructed climatic data sets. The focus lies on the identification and possible quantification of the contribution of sealevel pressure (wind), air-temperature and precipitation to the low-frequency (decadal and multi-decadal) variability of Baltic Sea level. It is known that the wind forcing is the main factor explaining average Baltic Sea level variability at inter-annual to decadal timescales, especially in wintertime. In this thesis it is statistically estimated to what extent other regional climate factors contribute to the spatially heterogeneous Baltic Sea level variations around the isostatic trend at multi-decadal timescales. Although the statistical analysis cannot be completely conclusive, as the potential climate drivers are all statistically interrelated to some degree, the results indicate that precipitation should be taken into account as an explanatory variable for sea-level variations. On the one hand it has been detected that the amplitude of the annual cycle of Baltic Sea level has increased throughout the 20th century and precipitation seems to be the only factor among those analysed (wind through SLP field, barometric effect, temperature and precipitation) that can account for this evolution. On the other hand, precipitation increases the ability to hindcast inter-annual variations of sea level in some regions and seasons, especially in the Southern Baltic in summertime. The mechanism by which precipitation exerts its influence on Baltic Sea level is not ascertained in this statistical analysis due to the lack of long salinity time series. This result, however, represents a working hypothesis that can be confirmed or disproved by long simulations of the Baltic Sea system - ocean
Tuan, P H; Yu, Y T; Chiang, P Y; Liang, H C; Huang, K F; Chen, Y F
2012-02-01
We thoroughly analyze the level statistics and eigenfunctions in concentric as well as nonconcentric square torus billiards. We confirm the characteristics of quantum and classical correspondence and the existence of scarred and superscarred modes in concentric square torus billiards. Furthermore, we not only verify that the transition from regular to chaotic behaviors can be manifested in nonconcentric square torus billiards, but also develop an analytical distribution to excellently fit the numerical level statistics. Finally, we intriguingly observe that numerous eigenstates commonly exhibit the wave patterns to be an ensemble of classical diamond trajectories, as the effective wavelengths are considerably shorter than the size of internal hole.
Low-level contrast statistics are diagnostic of invariance of natural textures.
Groen, Iris I A; Ghebreab, Sennay; Lamme, Victor A F; Scholte, H Steven
2012-01-01
Texture may provide important clues for real world object and scene perception. To be reliable, these clues should ideally be invariant to common viewing variations such as changes in illumination and orientation. In a large image database of natural materials, we found textures with low-level contrast statistics that varied substantially under viewing variations, as well as textures that remained relatively constant. This led us to ask whether textures with constant contrast statistics give rise to more invariant representations compared to other textures. To test this, we selected natural texture images with either high (HV) or low (LV) variance in contrast statistics and presented these to human observers. In two distinct behavioral categorization paradigms, participants more often judged HV textures as "different" compared to LV textures, showing that textures with constant contrast statistics are perceived as being more invariant. In a separate electroencephalogram (EEG) experiment, evoked responses to single texture images (single-image ERPs) were collected. The results show that differences in contrast statistics correlated with both early and late differences in occipital ERP amplitude between individual images. Importantly, ERP differences between images of HV textures were mainly driven by illumination angle, which was not the case for LV images: there, differences were completely driven by texture membership. These converging neural and behavioral results imply that some natural textures are surprisingly invariant to illumination changes and that low-level contrast statistics are diagnostic of the extent of this invariance.
Spectral-statistics properties of the experimental and theoretical light meson spectra
Energy Technology Data Exchange (ETDEWEB)
Munoz, L., E-mail: laura@nuc5.fis.ucm.es [European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT), Villa Tambosi, Strada delle Tabarelle 286, Villazzano, I-38123 (Italy); Fernandez-Ramirez, C., E-mail: cesar@nuc2.fis.ucm.es [European Centre for Theoretical Studies in Nuclear Physics and Related Areas (ECT), Villa Tambosi, Strada delle Tabarelle 286, Villazzano, I-38123 (Italy); Grupo de Fisica Nuclear, Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Relano, A., E-mail: armando.relano@gmail.com [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 123, E-28006 Madrid (Spain); Departamento de Fisica Aplicada I, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain); Retamosa, J. [Grupo de Fisica Nuclear, Departamento de Fisica Atomica, Molecular y Nuclear, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, Avda. Complutense s/n, E-28040 Madrid (Spain)
2012-03-29
We present a robust analysis of the spectral fluctuations exhibited by the light meson spectrum. This analysis provides information about the degree of chaos in light mesons and may be useful to get some insight on the underlying interactions. Our analysis unveils that the statistical properties of the light meson spectrum are close, but not exactly equal, to those of chaotic systems. In addition, we have analyzed several theoretical spectra including the latest lattice QCD calculation. With a single exception, their statistical properties are close to those of a generic integrable system, and thus incompatible with the experimental spectrum.
DEFF Research Database (Denmark)
Hansen, Jens Zangenberg; Brøndsted, Povl
2013-01-01
is compared to a numerical microstructure generator using Monte Carlo simulations. It is shown that the numerical microstructure generator produces fibre arrangements that are statistically similar to the observed, which indicates a reliable and consistent SRVE. The microstructural effects of a parametric......A quantitative study is carried out regarding the statistical properties of the fibre architecture found in composite laminates and that generated numerically using Statistical Representative Volume Elements (SRVE’s). The aim is to determine the reliability and consistency of SRVE...
Data revisions and the statistical relation of global mean sea-level and temperature
DEFF Research Database (Denmark)
Hillebrand, Eric; Johansen, Søren; Schmith, Torben
We study the stability of the estimated statistical relation of global mean temperature and global mean sea-level with regard to data revisions. Using three different model specifications proposed in the literature, we compare coefficient estimates and forecasts using two different vintages...
Koparan, Timur; Güven, Bülent
2015-01-01
The point of this study is to define the effect of project-based learning approach on 8th Grade secondary-school students' statistical literacy levels for data representation. To achieve this goal, a test which consists of 12 open-ended questions in accordance with the views of experts was developed. Seventy 8th grade secondary-school students, 35…
A Multidisciplinary Graduate Level Project-Based Programme in Applied Statistics.
Ojeda, M. M.; Sahai, H.
2003-01-01
Addresses the use of a project-based approach for designing a one-year graduate level program in applied statistics. Describes the pedagogical approach, academic setting, and learning activities in a multidisciplinary context. Comments on the implementation of such a program based on the results from five successive graduating classes at the…
Shukla, Pragya
2004-01-01
We find that the statistics of levels undergoing metal-insulator transition in systems with multi-parametric Gaussian disorders and non-interacting electrons behaves in a way similar to that of the single parametric Brownian ensembles \\cite{dy}. The latter appear during a Poisson $\\to$ Wigner-Dyson transition, driven by a random perturbation. The analogy provides the analytical evidence for the single parameter scaling of the level-correlations in disordered systems as well as a tool to obtai...
Shukla, Pragya
2004-01-01
We find that the statistics of levels undergoing metal-insulator transition in systems with multi-parametric Gaussian disorders and non-interacting electrons behaves in a way similar to that of the single parametric Brownian ensembles \\cite{dy}. The latter appear during a Poisson $\\to$ Wigner-Dyson transition, driven by a random perturbation. The analogy provides the analytical evidence for the single parameter scaling of the level-correlations in disordered systems as well as a tool to obtai...
The statistical properties of stars and their dependence on metallicity: the effects of opacity
Bate, Matthew R
2014-01-01
We report the statistical properties of stars and brown dwarfs obtained from four radiation hydrodynamical simulations of star cluster formation that resolve masses down to the opacity limit for fragmentation. The calculations are identical except for their dust and gas opacities. Assuming dust opacity is proportional to metallicity, the calculations span a range of metallicities from 1/100 to 3 times solar, although we emphasise that changing the metallicity has other thermodynamic effects that the calculations do not capture (e.g. on the thermal coupling between gas and dust). All four calculations produce stellar populations whose statistical properties are difficult to distinguish from observed stellar systems, and we find no significant dependence of stellar properties on opacity. The mass functions and properties of multiple stellar systems are consistent with each other. However, we find protostellar mergers are more common with lower opacities. Combining the results from the three calculations with th...
Statistical analysis of global surface air temperature and sea level using cointegration methods
DEFF Research Database (Denmark)
Schmith, Torben; Johansen, Søren; Thejll, Peter
Global sea levels are rising which is widely understood as a consequence of thermal expansion and melting of glaciers and land-based ice caps. Due to physically-based models being unable to simulate observed sea level trends, semi-empirical models have been applied as an alternative for projecting...... of future sea levels. There is in this, however, potential pitfalls due to the trending nature of the time series. We apply a statistical method called cointegration analysis to observed global sea level and surface air temperature, capable of handling such peculiarities. We find a relationship between sea...... level and temperature and find that temperature causally depends on the sea level, which can be understood as a consequence of the large heat capacity of the ocean. We further find that the warming episode in the 1940s is exceptional in the sense that sea level and warming deviates from the expected...
Full counting statistics in the self-dual interacting resonant level model.
Carr, Sam T; Bagrets, Dmitry A; Schmitteckert, Peter
2011-11-11
We present a general technique to obtain the zero temperature cumulant generating function of the full counting statistics of charge transfer in interacting impurity models out of equilibrium from time-dependent simulations on a lattice. We demonstrate the technique with application to the self-dual interacting resonant level model, where very good agreement between numerical simulations using the density matrix renormalization group and those obtained analytically from the thermodynamic Bethe ansatz is found. We show from the exact form of counting statistics that the quasiparticles involved in transport carry charge 2e in the low bias regime and e/2 in the high bias regime.
Level and width statistics of the open many-body systems
Mizutori, Shoujirou; Aiba, Hirokazu
2016-06-01
The level and width statistics of the two kinds of the random matrix models coupled to the continuum are analyzed. In the first model, the gaussian orthogonal ensemble with random couplings to the continuum, not only the width statistics deviate from the Porter-Thomas distribution due to the super-radiant mechanism, but also the distribution of the nearest neighbor level spacings shows deviation from the Wigner one simultaneously. In the second model, the two body random ensemble with correlated couplings to the continuum, the correlation between the target and the compound states leads to the global energy dependence of the widths. Within the narrow energy interval where states with widths deviating from the global energy dependence lie, the distributions behave similar way with the case of the random couplings. Namely, the deviation of statistics of the nearest neighbor level spacings from the Wigner distribution and the deviation of the width statistics from the Porter-Thomas distribution take place simultaneously within the models we investigated.
Wu, S.-S.; Wang, L.; Qiu, X.
2008-01-01
This article presents a deterministic model for sub-block-level population estimation based on the total building volumes derived from geographic information system (GIS) building data and three census block-level housing statistics. To assess the model, we generated artificial blocks by aggregating census block areas and calculating the respective housing statistics. We then applied the model to estimate populations for sub-artificial-block areas and assessed the estimates with census populations of the areas. Our analyses indicate that the average percent error of population estimation for sub-artificial-block areas is comparable to those for sub-census-block areas of the same size relative to associated blocks. The smaller the sub-block-level areas, the higher the population estimation errors. For example, the average percent error for residential areas is approximately 0.11 percent for 100 percent block areas and 35 percent for 5 percent block areas.
DEFF Research Database (Denmark)
Perrotta, Serena; D'Odorico, Valentina; Prochaska, J. Xavier
2016-01-01
We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and intervening NALs without taking into account any a priori definition or velocity cut-off. We analyze the spectra of 100 quasars...
Statistical mechanical properties of polymer configurations which enclose a constant area
Khandekar, D.C.; Wiegel, F.W.
1988-01-01
The statistical mechanical properties of plane polymer loops enclosing a constant area are investigated, using a continuous model from the start. For this purpose an analytic expression for the generating functional is obtained, which in turn is used to derive (1) the distribution function for the e
Lai, Dejian; Huang, Jin; Risser, Jan M.; Kapadia, Asha S.
2008-01-01
In this article, we report statistical properties of two classes of generalized Gini coefficients (G1 and G2). The theoretical results were assessed via Monte Carlo simulations. Further, we used G1 and G2 on life expectancy to measure health inequalities among the provinces of China and the states of the United States. For China, the results…
Quantum Statistical Properties of Binomial Field Interacting with Two Entangled Atoms
Institute of Scientific and Technical Information of China (English)
JIAO Zhi-Yong; MA Jun-Mao; SHANG Yong-Tao; LI Ning; FU Xia
2008-01-01
Quantum statistical properties of the binomial field interacting with the two entangled atoms are investi-gated for the different initial conditions. It is found that the sub-Poissonian distribution and the antibunching effect can be presented for the certain ranges of the involved parameters.
Energy Technology Data Exchange (ETDEWEB)
A.G. Crook Company
1993-04-01
This report was prepared by the A.G. Crook Company, under contract to Bonneville Power Administration, and provides statistics of seasonal volumes and streamflow for 28 selected sites in the Columbia River Basin.
Statistical and coherence properties of radiation from X-ray free electron lasers
Saldin, E L; Yurkov, M V
2009-01-01
We describe statistical and coherence properties of the radiation from x-ray free electron lasers (XFEL). It is shown that the X-ray FEL radiation before saturation is described with gaussian statistics. Particularly important is the case of the optimized X-ray FEL, studied in detail. Applying similarity techniques to the results of numerical simulations allowed us to find universal scaling relations for the main characteristics of an X-ray FEL operating in the saturation regime: efficiency, coherence time and degree of transverse coherence. We find that with an appropriate normalization of these quantities, they are functions of only the ratio of the geometrical emittance of the electron beam to the radiation wavelength. Statistical and coherence properties of the higher harmonics of the radiation are highlighted as well.
Statistical Properties of Solar Flares and Comparison to Other Impulsive Energy Release Events
Lepreti, Fabio; Kossobokov, Vladimir G.; Carbone, Vincenzo
Impulsive energy release events are observed in many natural systems. Solar flares are certainly among the most remarkable examples of such processes. In the last years the study of solar flare statistical properties has received considerable attention in the context of solar flare models based on different approaches, such as Self Organized Criticality (SOC) or magnetohydrodynamic (MHD) turbulence. In this talk the main statistical properties of solar flares will be presented and compared to those of other well known impulsive processes, such as earthquakes and soft γ-ray flashes occurring on neutron stars. It is shown that the these phenomena are characterized by different statistics that cannot be rescaled onto a single, universal curve and that this holds even for the same phenomenon, when observed in different periods or at different locations. Our results indicate apparent complexity of impulsive energy release processes, which neither follow a common behavior nor could be attributed to a universal physical mechanism.
A statistical property of multiagent learning based on Markov decision process.
Iwata, Kazunori; Ikeda, Kazushi; Sakai, Hideaki
2006-07-01
We exhibit an important property called the asymptotic equipartition property (AEP) on empirical sequences in an ergodic multiagent Markov decision process (MDP). Using the AEP which facilitates the analysis of multiagent learning, we give a statistical property of multiagent learning, such as reinforcement learning (RL), near the end of the learning process. We examine the effect of the conditions among the agents on the achievement of a cooperative policy in three different cases: blind, visible, and communicable. Also, we derive a bound on the speed with which the empirical sequence converges to the best sequence in probability, so that the multiagent learning yields the best cooperative result.
Statistical analysis of global surface temperature and sea level using cointegration methods
DEFF Research Database (Denmark)
Schmidt, Torben; Johansen, Søren; Thejll, Peter
2012-01-01
Global sea levels are rising which is widely understood as a consequence of thermal expansion and melting of glaciers and land-based ice caps. Due to the lack of representation of ice-sheet dynamics in present-day physically-based climate models being unable to simulate observed sea level trends......, semi-empirical models have been applied as an alternative for projecting of future sea levels. There is in this, however, potential pitfalls due to the trending nature of the time series. We apply a statistical method called cointegration analysis to observed global sea level and land-ocean surface air...... temperature, capable of handling such peculiarities. We find a relationship between sea level and temperature and find that temperature causally depends on the sea level, which can be understood as a consequence of the large heat capacity of the ocean. We further find that the warming episode in the 1940s...
Large eddy simulation of turbulent statistical and transport properties in stably stratified flows
Institute of Scientific and Technical Information of China (English)
Xiang QIU; Yong-xiang HUANG; Zhi-ming LU; Yu-lu LIU
2009-01-01
Three dimensional large eddy simulation (LES) is performed in the inves-tigation of stably stratified turbulence with a sharp thermal interface. Main results are focused on the turbulent characteristic scale, statistical properties, transport properties,and temporal and spatial evolution of the scalar field. Results show that the buoyancy scale increases first, and then goes to a certain constant value. The stronger the mean shear, the larger the buoyancy scale. The overturning scale increases with the flow, and the mean shear improves the overturning scale. The flatness factor of temperature de-parts from the Ganssian distribution in a fairly large region, and its statistical properties are clearly different from those of the velocity fluctuations in strong stratified cases. Tur-bulent mixing starts from small scale motions, and then extends to large scale motions.
Statistical Properties of Diffuse Lyman-alpha Halos around Star-forming Galaxies at z~2
Momose, Rieko; Nakajima, Kimihiko; Ono, Yoshiaki; Shibuya, Takatoshi; Shimasaku, Kazuhiro; Yuma, Suraphong; Mori, Masao; Umemura, Masayuki
2015-01-01
We present statistical properties of diffuse Lyman-alpha halos (LAHs) around high-$z$ star-forming galaxies with large Subaru samples of Lyman-alpha emitters (LAEs) at $z=2.2$. We make subsamples defined by the physical quantities of LAEs' central Lyman-alpha luminosities, UV magnitudes, Lyman-alpha equivalent widths, and UV slopes, and investigate LAHs' radial surface brightness (SB) profiles and scale lengths $r_n$ as a function of these physical quantities. We find that there exist prominent LAHs around LAEs with faint Lyman-alpha luminosities, bright UV luminosities, and small Lyman-alpha equivalent widths in cumulative radial Lyman-alpha SB profiles. We confirm this trend with the anti-correlation between $r_n$ and Lyman-alpha luminosities (equivalent widths) based on the Spearman's rank correlation coefficient that is $\\rho=-0.9$ ($-0.7$) corresponding to the $96\\%$ ($93\\%$) confidence level, although the correlation between $r_n$ and UV magnitudes is not clearly found in the rank correlation coefficien...
Białous, Małgorzata; Yunko, Vitalii; Bauch, Szymon; Ławniczak, Michał; Dietz, Barbara; Sirko, Leszek
2016-09-01
We present experimental studies of the power spectrum and other fluctuation properties in the spectra of microwave networks simulating chaotic quantum graphs with violated time reversal invariance. On the basis of our data sets, we demonstrate that the power spectrum in combination with other long-range and also short-range spectral fluctuations provides a powerful tool for the identification of the symmetries and the determination of the fraction of missing levels. Such a procedure is indispensable for the evaluation of the fluctuation properties in the spectra of real physical systems like, e.g., nuclei or molecules, where one has to deal with the problem of missing levels.
Statistical properties of spike trains universal and stimulus-dependent aspects
Brenner, N; Bialek, W; De van Steveninck, R R
1999-01-01
Statistical properties of spike trains measured from a sensory neuron in-vivo are studied experimentally and theoretically. Experiments are performed on an identified neuron in the visual system of the blowfly. It is shown that the spike trains exhibit universal behavior over short time, modulated by a stimulus-dependent envelope over long time. A model of the neuron as a nonlinear oscillator driven by noise and an external stimulus, is suggested to account for these results. The model enables a theoretic distinction of the effects of internal neuronal properties from effects of external stimulus properties, and their identification in the measured spike trains. The universal regime is characterized by one dimensionless parameter, representing the internal degree of irregularity, which is determined both by the sensitivity of the neuron and by the properties of the noise. The envelope is related in a simple way to properties of the input stimulus as seen through nonlinearity of the neural response. Explicit f...
Time-dependent statistical and correlation properties of neural signals during handwriting.
Directory of Open Access Journals (Sweden)
Valery I Rupasov
Full Text Available To elucidate the cortical control of handwriting, we examined time-dependent statistical and correlational properties of simultaneously recorded 64-channel electroencephalograms (EEGs and electromyograms (EMGs of intrinsic hand muscles. We introduced a statistical method, which offered advantages compared to conventional coherence methods. In contrast to coherence methods, which operate in the frequency domain, our method enabled us to study the functional association between different neural regions in the time domain. In our experiments, subjects performed about 400 stereotypical trials during which they wrote a single character. These trials provided time-dependent EMG and EEG data capturing different handwriting epochs. The set of trials was treated as a statistical ensemble, and time-dependent correlation functions between neural signals were computed by averaging over that ensemble. We found that trial-to-trial variability of both the EMGs and EEGs was well described by a log-normal distribution with time-dependent parameters, which was clearly distinguished from the normal (Gaussian distribution. We found strong and long-lasting EMG/EMG correlations, whereas EEG/EEG correlations, which were also quite strong, were short-lived with a characteristic correlation durations on the order of 100 ms or less. Our computations of correlation functions were restricted to the [Formula: see text] spectral range (13-30 Hz of EEG signals where we found the strongest effects related to handwriting. Although, all subjects involved in our experiments were right-hand writers, we observed a clear symmetry between left and right motor areas: inter-channel correlations were strong if both channels were located over the left or right hemispheres, and 2-3 times weaker if the EEG channels were located over different hemispheres. Although we observed synchronized changes in the mean energies of EEG and EMG signals, we found that EEG/EMG correlations were much
Thapaliya, Kiran; Pyun, Jae-Young; Park, Chun-Su; Kwon, Goo-Rak
2013-01-01
The level set approach is a powerful tool for segmenting images. This paper proposes a method for segmenting brain tumor images from MR images. A new signed pressure function (SPF) that can efficiently stop the contours at weak or blurred edges is introduced. The local statistics of the different objects present in the MR images were calculated. Using local statistics, the tumor objects were identified among different objects. In this level set method, the calculation of the parameters is a challenging task. The calculations of different parameters for different types of images were automatic. The basic thresholding value was updated and adjusted automatically for different MR images. This thresholding value was used to calculate the different parameters in the proposed algorithm. The proposed algorithm was tested on the magnetic resonance images of the brain for tumor segmentation and its performance was evaluated visually and quantitatively. Numerical experiments on some brain tumor images highlighted the efficiency and robustness of this method.
Photon-statistics excitation spectroscopy of a single two-level system
Strauß, Max; Placke, Marlon; Kreinberg, Sören; Schneider, Christian; Kamp, Martin; Höfling, Sven; Wolters, Janik; Reitzenstein, Stephan
2016-06-01
We investigate the influence of the photon statistics on the excitation dynamics of a single two-level system. A single semiconductor quantum dot represents the two-level system and is resonantly excited either with coherent laser light, or excited with chaotic light, with photon statistics corresponding to that of thermal radiation. Experimentally, we observe a reduced absorption cross section under chaotic excitation in the steady state. In the transient regime, the Rabi oscillations observable under coherent excitation disappear under chaotic excitation. Likewise, in the emission spectrum, the well-known Mollow triplet, which we observe under coherent drive, disappears under chaotic excitation. Our observations are fully consistent with theoretical predictions based on the semiclassical Bloch equation approach.
Non-parametric group-level statistics for source-resolved ERP analysis.
Lee, Clement; Miyakoshi, Makoto; Delorme, Arnaud; Cauwenberghs, Gert; Makeig, Scott
2015-01-01
We have developed a new statistical framework for group-level event-related potential (ERP) analysis in EEGLAB. The framework calculates the variance of scalp channel signals accounted for by the activity of homogeneous clusters of sources found by independent component analysis (ICA). When ICA data decomposition is performed on each subject's data separately, functionally equivalent ICs can be grouped into EEGLAB clusters. Here, we report a new addition (statPvaf) to the EEGLAB plug-in std_envtopo to enable inferential statistics on main effects and interactions in event related potentials (ERPs) of independent component (IC) processes at the group level. We demonstrate the use of the updated plug-in on simulated and actual EEG data.
Photon-Statistics Excitation Spectroscopy of a Single Two Level System
Strauß, M; Kreinberg, S; Schneider, C; Kamp, M; Höfling, S; Wolters, J; Reitzenstein, S
2016-01-01
We investigate the influence of the photon statistics on the excitation dynamics of a single two level system. A single semiconductor quantum dot represents the two level system and is resonantly excited either with coherent laser light, or excited with chaotic light, with photon statistics corresponding to that of thermal radiation. Experimentally, we observe a reduced absorption cross-section under chaotic excitation in the steady-state. In the transient regime, the Rabi oscillations observable under coherent excitation disappear under chaotic excitation. Likewise, in the emission spectrum the well-known Mollow triplet, which we observe under coherent drive, disappears under chaotic excitation. Our observations are fully consistent with theoretical predictions based on the semi-classical Bloch equation approach.
Moisture properties of self-levelling flooring compounds
Anderberg, Anders
2004-01-01
Self-levelling flooring compounds (SLC) are used to level substrates (mainly concrete slabs) before applying final floor coverings. Although it is an extensively used product, only limited research has so far been published concerning their moisture properties. This report focuses on moisture properties of SLC and describes methods for determining them. Moisture properties of materials are important for the calculation of drying times and moisture loads and for prediction of ion transport and...
Full counting statistics of level renormalization in electron transport through double quantum dots.
Luo, JunYan; Jiao, HuJun; Shen, Yu; Cen, Gang; He, Xiao-Ling; Wang, Changrong
2011-04-13
We examine the full counting statistics of electron transport through double quantum dots coupled in series, with particular attention being paid to the unique features originating from level renormalization. It is clearly illustrated that the energy renormalization gives rise to a dynamic charge blockade mechanism, which eventually results in super-Poissonian noise. Coupling of the double dots to an external heat bath leads to dephasing and relaxation mechanisms, which are demonstrated to suppress the noise in a unique way.
Full counting statistics of level renormalization in electron transport through double quantum dots
Energy Technology Data Exchange (ETDEWEB)
Luo Junyan; Shen Yu; Cen Gang; He Xiaoling; Wang Changrong [School of Science, Zhejiang University of Science and Technology, Hangzhou 310023 (China); Jiao Hujun, E-mail: jyluo@zust.edu.cn [Department of Physics, Shanxi University, Taiyuan, Shanxi 030006 (China)
2011-04-13
We examine the full counting statistics of electron transport through double quantum dots coupled in series, with particular attention being paid to the unique features originating from level renormalization. It is clearly illustrated that the energy renormalization gives rise to a dynamic charge blockade mechanism, which eventually results in super-Poissonian noise. Coupling of the double dots to an external heat bath leads to dephasing and relaxation mechanisms, which are demonstrated to suppress the noise in a unique way.
Digital Repository Service at National Institute of Oceanography (India)
Pankajakshan, T.; Shikauchi, A.; Sugimori, Y.; Kubota, M.
Vol. 49, pp. 551 to 558. 1993 A Statistical Method to Get Surface Level Air-Temperature from Satellite Observations of Precipitable Water PANKAJAKSHAN THADATHIL*, AKIRA SHIKAUCHI, YASUHIRO SUGIMORI and MASAHISA KUBOTA School of Marine Science... observations for getting the estimates of heat flux across the air-sea boundary (Miller, 1981; Liu, 1988). Bulk method has widely been used for this purpose and the parameters required are: sea surface temperature, and wind speed, air-temperature and specific...
Response properties of ON-OFF retinal ganglion cells to high-order stimulus statistics.
Xiao, Lei; Gong, Han-Yan; Gong, Hai-Qing; Liang, Pei-Ji; Zhang, Pu-Ming
2014-10-17
The visual stimulus statistics are the fundamental parameters to provide the reference for studying visual coding rules. In this study, the multi-electrode extracellular recording experiments were designed and implemented on bullfrog retinal ganglion cells to explore the neural response properties to the changes in stimulus statistics. The changes in low-order stimulus statistics, such as intensity and contrast, were clearly reflected in the neuronal firing rate. However, it was difficult to distinguish the changes in high-order statistics, such as skewness and kurtosis, only based on the neuronal firing rate. The neuronal temporal filtering and sensitivity characteristics were further analyzed. We observed that the peak-to-peak amplitude of the temporal filter and the neuronal sensitivity, which were obtained from either neuronal ON spikes or OFF spikes, could exhibit significant changes when the high-order stimulus statistics were changed. These results indicate that in the retina, the neuronal response properties may be reliable and powerful in carrying some complex and subtle visual information.
Fuchs, Julia; Cermak, Jan; Andersen, Hendrik
2017-04-01
This study aims at untangling the impacts of external dynamics and local conditions on cloud properties in the Southeast Atlantic (SEA) by combining satellite and reanalysis data using multivariate statistics. The understanding of clouds and their determinants at different scales is important for constraining the Earth's radiative budget, and thus prominent in climate-system research. In this study, SEA stratocumulus cloud properties are observed not only as the result of local environmental conditions but also as affected by external dynamics and spatial origins of air masses entering the study area. In order to assess to what extent cloud properties are impacted by aerosol concentration, air mass history, and meteorology, a multivariate approach is conducted using satellite observations of aerosol and cloud properties (MODIS, SEVIRI), information on aerosol species composition (MACC) and meteorological context (ERA-Interim reanalysis). To account for the often-neglected but important role of air mass origin, information on air mass history based on HYSPLIT modeling is included in the statistical model. This multivariate approach is intended to lead to a better understanding of the physical processes behind observed stratocumulus cloud properties in the SEA.
Directory of Open Access Journals (Sweden)
Vladimir I. Borodulin
2014-01-01
Full Text Available As known from previous studies, the deterministic turbulence (DeTu is a post-transitional flow that is turbulent according to the generally accepted statistical characteristics but possesses, meanwhile, a significant degree of determinism, i.e., reproducibility of its instantaneous structure. It is found that the DeTu can occur in those cases when transition is caused by convective instabilities; in boundary layers, in particular. The present paper is devoted to a brief description of history of discovering the DeTu phenomenon, as well as to some recent advance in investigation of instantaneous and statistical properties of such turbulent boundary layer flows.
High order statistics based blind deconvolution of bi-level images with unknown intensity values.
Kim, Jeongtae; Jang, Soohyun
2010-06-07
We propose a novel linear blind deconvolution method for bi-level images. The proposed method seeks an optimal point spread function and two parameters that maximize a high order statistics based objective function. Unlike existing minimum entropy deconvolution and least squares minimization methods, the proposed method requires neither unrealistic assumption that the pixel values of a bi-level image are independently identically distributed samples of a random variable nor tuning of regularization parameters.We demonstrate the effectiveness of the proposed method in simulations and experiments.
Cui, Wenchao; Wang, Yi; Lei, Tao; Fan, Yangyu; Feng, Yan
2013-01-01
This paper presents a variational level set method for simultaneous segmentation and bias field estimation of medical images with intensity inhomogeneity. In our model, the statistics of image intensities belonging to each different tissue in local regions are characterized by Gaussian distributions with different means and variances. According to maximum a posteriori probability (MAP) and Bayes' rule, we first derive a local objective function for image intensities in a neighborhood around each pixel. Then this local objective function is integrated with respect to the neighborhood center over the entire image domain to give a global criterion. In level set framework, this global criterion defines an energy in terms of the level set functions that represent a partition of the image domain and a bias field that accounts for the intensity inhomogeneity of the image. Therefore, image segmentation and bias field estimation are simultaneously achieved via a level set evolution process. Experimental results for synthetic and real images show desirable performances of our method.
Badran, M; Morsy, R; Soliman, H; Elnimr, T
2016-01-01
The trace elements metabolism has been reported to possess specific roles in the pathogenesis and progress of diabetes mellitus. Due to the continuous increase in the population of patients with Type 2 diabetes (T2D), this study aims to assess the levels and inter-relationships of fast blood glucose (FBG) and serum trace elements in Type 2 diabetic patients. This study was conducted on 40 Egyptian Type 2 diabetic patients and 36 healthy volunteers (Hospital of Tanta University, Tanta, Egypt). The blood serum was digested and then used to determine the levels of 24 trace elements using an inductive coupled plasma mass spectroscopy (ICP-MS). Multivariate statistical analysis depended on correlation coefficient, cluster analysis (CA) and principal component analysis (PCA), were used to analysis the data. The results exhibited significant changes in FBG and eight of trace elements, Zn, Cu, Se, Fe, Mn, Cr, Mg, and As, levels in the blood serum of Type 2 diabetic patients relative to those of healthy controls. The statistical analyses using multivariate statistical techniques were obvious in the reduction of the experimental variables, and grouping the trace elements in patients into three clusters. The application of PCA revealed a distinct difference in associations of trace elements and their clustering patterns in control and patients group in particular for Mg, Fe, Cu, and Zn that appeared to be the most crucial factors which related with Type 2 diabetes. Therefore, on the basis of this study, the contributors of trace elements content in Type 2 diabetic patients can be determine and specify with correlation relationship and multivariate statistical analysis, which confirm that the alteration of some essential trace metals may play a role in the development of diabetes mellitus. Copyright © 2015 Elsevier GmbH. All rights reserved.
Assaraf, Roland
2014-12-01
We show that the recently proposed correlated sampling without reweighting procedure extends the locality (asymptotic independence of the system size) of a physical property to the statistical fluctuations of its estimator. This makes the approach potentially vastly more efficient for computing space-localized properties in large systems compared with standard correlated methods. A proof is given for a large collection of noninteracting fragments. Calculations on hydrogen chains suggest that this behavior holds not only for systems displaying short-range correlations, but also for systems with long-range correlations.
STATISTICAL PROPERTIES OF HIGH-FREQUENCY INTERNAL WAVES IN QINGDAO OFFSHORE AREA OF THE YELLOW SEA
Institute of Scientific and Technical Information of China (English)
王涛; 高天赋
2002-01-01
Densely-sampled thermistor chain data obtained from a shallow-water acoustics experiment in the Yellow Sea off the coast of Qingdao were analyzed to examine the statistical properties of the 6 to 520 cpd frequency band internal waves observed. The negative skewness coefficients and the greater-than-3 kurtosis coefficients indicated non-Gaussianity of the internal waves. The probability distributions were negatively skewed and abnormally high peaks. Nonlinear properties, as exemplified by the asymmetric waveshapes of the internal waves in the offshore area are described quantitatively.
Construction of photon-added spin coherent states and their statistical properties
Energy Technology Data Exchange (ETDEWEB)
Berrada, K., E-mail: kberrada@ictp.it [Al Imam Mohammad Ibn Saud Islamic University (IMSIU), College of Science, Department of Physics, Riyadh (Saudi Arabia); The Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, Miramare-Trieste (Italy)
2015-07-15
In the present work, we construct and investigate some properties of the photon-added spin coherent states (PA-SCSs). The Klauder’s minimal set of conditions required to obtain coherent states are discussed. We give the analytical form for the positive weight function in the resolution of unity. Finally, we examine the statistical properties of the PA-SCSs in terms of different parameters using the Mandel’s Q-parameter. All these quantities are expressed in terms of hypergeometric and Meijer G-functions, and so, the PA-SCSs are a new field of application for these functions.
Directory of Open Access Journals (Sweden)
J. D. Pandey
2012-12-01
Full Text Available Thermodynamic properties of liquids and liquid mixtures play very important role in understanding the nature of molecular interactions occurring in the system. In the present work different thermodynamic properties of 15 pure liquids and 34 equimolar binary liquid mixtures of benzene, toluene, p-xylene, chlorobenzene and 1-chloronaphthalene with linear and branched alkanes have been computed with the help of Flory’s statistical theory (FST, Hard sphere equation of state (HSE and Hole theory (HT simultaneously. The calculated values are compared with the experimental findings collected from literature and quite satisfactory results are obtained.
Movement and respiration detection using statistical properties of the FMCW radar signal
Kiuru, Tero
2016-07-26
This paper presents a 24 GHz FMCW radar system for detection of movement and respiration using change in the statistical properties of the received radar signal, both amplitude and phase. We present the hardware and software segments of the radar system as well as algorithms with measurement results for two distinct use-cases: 1. FMCW radar as a respiration monitor and 2. a dual-use of the same radar system for smart lighting and intrusion detection. By using change in statistical properties of the signal for detection, several system parameters can be relaxed, including, for example, pulse repetition rate, power consumption, computational load, processor speed, and memory space. We will also demonstrate, that the capability to switch between received signal strength and phase difference enables dual-use cases with one requiring extreme sensitivity to movement and the other robustness against small sources of interference. © 2016 IEEE.
Ma, Junjun; Xiong, Xiong; He, Feng; Zhang, Wei
2017-04-01
The stock price fluctuation is studied in this paper with intrinsic time perspective. The event, directional change (DC) or overshoot, are considered as time scale of price time series. With this directional change law, its corresponding statistical properties and parameter estimation is tested in Chinese stock market. Furthermore, a directional change trading strategy is proposed for invest in the market portfolio in Chinese stock market, and both in-sample and out-of-sample performance are compared among the different method of model parameter estimation. We conclude that DC method can capture important fluctuations in Chinese stock market and gain profit due to the statistical property that average upturn overshoot size is bigger than average downturn directional change size. The optimal parameter of DC method is not fixed and we obtained 1.8% annual excess return with this DC-based trading strategy.
Statistical Property and Model for the Inter-Event Time of Terrorism Attacks
Zhu, Jun-Fang; Han, Xiao-Pu; Wang, Bing-Hong
2010-06-01
The inter-event time of terrorism attack events is investigated by empirical data and model analysis. Empirical evidence shows that it follows a scale-free property. In order to understand the dynamic mechanism of such a statistical feature, an opinion dynamic model with a memory effect is proposed on a two-dimensional lattice network. The model mainly highlights the role of individual social conformity and self-affirmation psychology. An attack event occurs when the order parameter indicating the strength of public opposition opinion is smaller than a critical value. Ultimately, the model can reproduce the same statistical property as the empirical data and gives a good understanding for the possible dynamic mechanism of terrorism attacks.
Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech
Přibil, J.; Přibilová, A.
2009-01-01
The paper addresses reflection of microintonation and spectral properties in male and female acted emotional speech. Microintonation component of speech melody is analyzed regarding its spectral and statistical parameters. According to psychological research of emotional speech, different emotions are accompanied by different spectral noise. We control its amount by spectral flatness according to which the high frequency noise is mixed in voiced frames during cepstral speech synthesis. Our experiments are aimed at statistical analysis of cepstral coefficient values and ranges of spectral flatness in three emotions (joy, sadness, anger), and a neutral state for comparison. Calculated histograms of spectral flatness distribution are visually compared and modelled by Gamma probability distribution. Histograms of cepstral coefficient distribution are evaluated and compared using skewness and kurtosis. Achieved statistical results show good correlation comparing male and female voices for all emotional states portrayed by several Czech and Slovak professional actors.
Fundamental properties of fracture and seismicity in a non extensive statistical physics framework.
Vallianatos, Filippos
2010-05-01
A fundamental challenge in many scientific disciplines concerns upscaling, that is, of determining the regularities and laws of evolution at some large scale, from those known at a lower scale. Earthquake physics is no exception, with the challenge of understanding the transition from the laboratory scale to the scale of fault networks and large earthquakes. In this context, statistical physics has a remarkably successful work record in addressing the upscaling problem in physics. It is natural then to consider that the physics of many earthquakes has to be studied with a different approach than the physics of one earthquake and in this sense we can consider the use of statistical physics not only appropriate but necessary to understand the collective properties of earthquakes [see Corral 2004, 2005a,b,c;]. A significant attempt is given in a series of works [Main 1996; Rundle et al., 1997; Main et al., 2000; Main and Al-Kindy, 2002; Rundle et al., 2003; Vallianatos and Triantis, 2008a] that uses classical statistical physics to describe seismicity. Then a natural question arises. What type of statistical physics is appropriate to commonly describe effects from fracture level to seismicity scale?? The application of non extensive statistical physics offers a consistent theoretical framework, based on a generalization of entropy, to analyze the behavior of natural systems with fractal or multi-fractal distribution of their elements. Such natural systems where long - range interactions or intermittency are important, lead to power law behavior. We note that this is consistent with a classical thermodynamic approach to natural systems that rapidly attain equilibrium, leading to exponential-law behavior. In the frame of non extensive statistical physics approach, the probability function p(X) is calculated using the maximum entropy formulation of Tsallis entropy which involves the introduction of at least two constraints (Tsallis et al., 1998). The first one is the
DEFF Research Database (Denmark)
Wang, W.; Hanson, Steen Grüner; Miyamoto, Y.;
2005-01-01
We present the first direct experimental evidence of the local properties of optical vortices in a random laser speckle field. We have observed the Berry anisotropy ellipse describing the anisotropic squeezing of phase lines close to vortex cores and quantitatively verified the Dennis angular...... momentum rule for its phase. Some statistics associated with vortices, such as density, anisotropy ellipse eccentricity, and its relation to zero crossings of real and imaginary parts of the random field, are also investigated by experiments....
A model of modulated diffusion. II. Numerical results on statistical properties
Energy Technology Data Exchange (ETDEWEB)
Bazzani, A.; Siboni, S.; Turchetti, G. [dell`Universita Bologna (Italy)] [and others
1994-08-01
We investigate numerically the statistical properties of a model of modulated diffusion for which we have already computed analytically the diffusion coefficient D. Our model is constructed by adding a deterministic or random noise to the frequency of an integrable isochronous system. We consider in particular the central limit theorem and the invariance principle and we show that they follow whenever D is positive and for any magnitude of the noise; we also investigate the asymptotic distribution in a case when D=0.
Statistical properties of the S-wave resonances of {sup 235}U
Energy Technology Data Exchange (ETDEWEB)
Leal, L.C.; Derrien, H.; Larson, N.M.
1997-06-01
The resonance parameters of {sup 235}U in the energy range 0 eV to 2.25 keV were obtained from a generalized least squares analysis of a large set of experimental data using the Reich-Moore formalism in the fitting code SAMMY. The aim of the present paper is to present the statistical properties of the s-wave resonance parameters generated from this study.
DEFF Research Database (Denmark)
Inwood, Jennifer; Lofi, Johanna; Davies, Sarah
2013-01-01
In this study, a novel application of a statistical approach is utilized for analysis of downhole logging data from Miocene-aged siliciclastic shelf sediments on the New Jersey Margin (eastern USA). A multivariate iterative nonhierarchical cluster analysis (INCA) of spectral gamma-ray logs from...... composition, and stratal geometries in response to sea-level changes. The novel approach of combining statistical analysis with detailed lithostratigraphic and seismic reflection data sets will be of interest to any scientists working with downhole logs, especially spectral gamma-ray data, and also provides...... a reference for the strengths and weaknesses of multi component analysis applied to continental margin lithofacies. The method presented here is appropriate for evaluating successions elsewhere and also has value for hydrocarbon exploration where sequence stratigraphy is a fundamental tool....
Photon absorption and emission statistics of a two-level atom in a cavity
Energy Technology Data Exchange (ETDEWEB)
Lee, Chang J. [Sun Moon University, Asan (Korea, Republic of)
2012-03-15
The absorption and the emission of photons by an atom involves quantum jumps between states. We investigate the quantum jump statistics for the system of a two-level atom and a single-mode cavity field. We use the Jaynes-Cummings model for this problem, perform Monte Carlo numerical simulations, and give a detailed exact analysis on these simulations. These studies reveal that the waiting-time distribution (WTD) for photon absorptions (emissions) has a unique novel statistic, and that the photon absorption (emission) rate is not uniform, but counter-intuitively depends on the position in the Rabi cycle. The effects of the nonclassical nature of the field on the WTD is discussed.
Misuse of statistics in the interpretation of data on low-level radiation
Energy Technology Data Exchange (ETDEWEB)
Hamilton, L.D.
1982-01-01
Four misuses of statistics in the interpretation of data of low-level radiation are reviewed: (1) post-hoc analysis and aggregation of data leading to faulty conclusions in the reanalysis of genetic effects of the atomic bomb, and premature conclusions on the Portsmouth Naval Shipyard data; (2) inappropriate adjustment for age and ignoring differences between urban and rural areas leading to potentially spurious increase in incidence of cancer at Rocky Flats; (3) hazard of summary statistics based on ill-conditioned individual rates leading to spurious association between childhood leukemia and fallout in Utah; and (4) the danger of prematurely published preliminary work with inadequate consideration of epidemiological problems - censored data - leading to inappropriate conclusions, needless alarm at the Portsmouth Naval Shipyard, and diversion of scarce research funds.
Probing the statistical properties of unknown texts: application to the Voynich Manuscript
Amancio, Diego R; Rybski, Diego; Oliveira, Osvaldo N; Costa, Luciano da F
2013-01-01
While the use of statistical physics methods to analyze large corpora has been useful to unveil many patterns in texts, no comprehensive investigation has been performed investigating the properties of statistical measurements across different languages and texts. In this study we propose a framework that aims at determining if a text is compatible with a natural language and which languages are closest to it, without any knowledge of the meaning of the words. The approach is based on three types of statistical measurements, i.e. obtained from first-order statistics of word properties in a text, from the topology of complex networks representing text, and from intermittency concepts where text is treated as a time series. Comparative experiments were performed with the New Testament in 15 different languages and with distinct books in English and Portuguese in order to quantify the dependency of the different measurements on the language and on the story being told in the book. The metrics found to be informa...
Directory of Open Access Journals (Sweden)
Muhammad Imran Akram
2012-01-01
Full Text Available This paper presents the statistical properties of the vehicle-to-vehicle Nakagami-Hoyt (Nakagami-q channel model under non-isotropic condition. The spatial time correlation function (STCF, the power spectral density (PSD, squared time autocorrelation function (SQCF, level crossing rate (LCR, and the average duration of Fade (ADF of the Nakagami-Hoyt channel have been derived under the assumption that both the transmitter and receiver are nonstationary having nonomnidirectional antennas. A simulator that uses the inverse-fast-fourier-transform- (IFFT- based computation method is designed for this model. The simulator and analytical results are compared.
Statistical properties of Joule heating rate, electric field and conductances at high latitudes
Directory of Open Access Journals (Sweden)
A. T. Aikio
2009-07-01
Full Text Available Statistical properties of Joule heating rate, electric field and conductances in the high latitude ionosphere are studied by a unique one-month measurement made by the EISCAT incoherent scatter radar in Tromsø (66.6 cgmlat from 6 March to 6 April 2006. The data are from the same season (close to vernal equinox and from similar sunspot conditions (about 1.5 years before the sunspot minimum providing an excellent set of data to study the MLT and K_{p} dependence of parameters with high temporal and spatial resolution.
All the parameters show a clear MLT variation, which is different for low and high K_{p} conditions. Our results indicate that the response of morning sector conductances and conductance ratios to increased magnetic activity is stronger than that of the evening sector. The co-location of Pedersen conductance maximum and electric field maximum in the morning sector produces the largest Joule heating rates 03–05 MLT for K_{p}≥3. In the evening sector, a smaller maximum occurs at 18 MLT. Minimum Joule heating rates in the nightside are statistically observed at 23 MLT, which is the location of the electric Harang discontinuity.
An important outcome of the paper are the fitted functions for the Joule heating rate as a function of electric field magnitude, separately for four MLT sectors and two activity levels (K_{p}<3 and K_{p}≥3. In addition to the squared electric field, the fit includes a linear term to study the possible anticorrelation or correlation between electric field and conductance. In the midday sector, positive correlation is found as well as in the morning sector for the high activity case. In the midnight and evening sectors, anticorrelation between electric field and conductance is obtained, i.e. high electric fields are associated with low conductances. This is expected to occur in the return current regions adjacent to
Firing statistics and correlations in spiking neurons: a level-crossing approach.
Badel, Laurent
2011-10-01
We present a time-dependent level-crossing theory for linear dynamical systems perturbed by colored Gaussian noise. We apply these results to approximate the firing statistics of conductance-based integrate-and-fire neurons receiving excitatory and inhibitory Poissonian inputs. Analytical expressions are obtained for three key quantities characterizing the neuronal response to time-varying inputs: the mean firing rate, the linear response to sinusoidally modulated inputs, and the pairwise spike correlation for neurons receiving correlated inputs. The theory yields tractable results that are shown to accurately match numerical simulations and provides useful tools for the analysis of interconnected neuronal populations.
Miao, Qiang; Zheng, Yujun
2016-06-29
In this paper, the nature of the multi-order resonance and coherent destruction of tunneling (CDT) for two-level system driven cross avoided crossing is investigated by employing the emitted photons 〈N〉 and the Mandel's Q parameter based on the photon counting statistics. An asymmetric feature of CDT is shown in the spectrum of Mandel's Q parameter. Also, the CDT can be employed to suppress the spontaneous decay and prolong waiting time noticeably. The photon emission pattern is of monotonicity in strong relaxation, and homogeneity in pure dephasing regime, respectively.
Nearest level spacing statistics in open chaotic systems: generalization of the Wigner surmise.
Poli, Charles; Luna-Acosta, Germán A; Stöckmann, Hans-Jürgen
2012-04-27
We investigate the nearest level spacing statistics of open chaotic wave systems. To this end we derive the spacing distributions for the three Wigner ensembles in the one-channel case. The theoretical results give a clear physical meaning of the modifications on the spacing distributions produced by the coupling to the environment. Based on the analytical expressions obtained, we then propose general expressions of the spacing distributions for any number of channels, valid from weak to strong coupling. The latter expressions contain one free parameter. The surmise is successfully compared with numerical simulations of non-Hermitian random matrices and with experimental data obtained with a lossy electromagnetic chaotic cavity.
Single molecule photon emission statistics of driven three-level systems.
Peng, Yonggang; Zheng, Yujun; Brown, Frank L H
2007-03-14
We study the statistics of photon emission from three-level single molecule systems. The generating function method [Y. Zheng and F. L. H. Brown, Phys. Rev. Lett. 90, 238305 (2003)] is used to calculate steady state absorption line shapes and Mandel's Q parameter as a function of excitation frequency, as well as the time dependence associated with approach to the steady state. The line shape calculations confirm known results derived via other methods, while the Q parameter results display complex frequency dependences not amenable to simple interpretation. This study confirms the applicability of the generating function formalism to multilevel quantum systems, including the proper modeling of quantum coherence effects.
Miao, Qiang; Zheng, Yujun
2016-06-01
In this paper, the nature of the multi-order resonance and coherent destruction of tunneling (CDT) for two-level system driven cross avoided crossing is investigated by employing the emitted photons and the Mandel’s Q parameter based on the photon counting statistics. An asymmetric feature of CDT is shown in the spectrum of Mandel’s Q parameter. Also, the CDT can be employed to suppress the spontaneous decay and prolong waiting time noticeably. The photon emission pattern is of monotonicity in strong relaxation, and homogeneity in pure dephasing regime, respectively.
Perceived depth in natural images reflects encoding of low-level luminance statistics.
Cooper, Emily A; Norcia, Anthony M
2014-08-27
Sighted animals must survive in an environment that is diverse yet highly structured. Neural-coding models predict that the visual system should allocate its computational resources to exploit regularities in the environment, and that this allocation should facilitate perceptual judgments. Here we use three approaches (natural scenes statistical analysis, a reanalysis of single-unit data from alert behaving macaque, and a behavioral experiment in humans) to address the question of how the visual system maximizes behavioral success by taking advantage of low-level regularities in the environment. An analysis of natural scene statistics reveals that the probability distributions for light increments and decrements are biased in a way that could be exploited by the visual system to estimate depth from relative luminance. A reanalysis of neurophysiology data from Samonds et al. (2012) shows that the previously reported joint tuning of V1 cells for relative luminance and binocular disparity is well matched to a predicted distribution of binocular disparities produced by natural scenes. Finally, we show that a percept of added depth can be elicited in images by exaggerating the correlation between luminance and depth. Together, the results from these three approaches provide further evidence that the visual system allocates its processing resources in a way that is driven by the statistics of the natural environment.
A Novel Statistical Technique for Determining the Properties of Exrasolar Planets
Starr Henderson, Cassandra; Skemer, Andrew; Morley, Caroline; Fortney, Jonathan J.
2017-01-01
By detecting light from extrasolar planets, we can measure their compositions and bulk physical properties. The technologies used to make these measurements are still in their infancy, and a lack of self-consistency suggests that previous observations have underestimated their systematic errors. We demonstrate a statistical method, newly applied to exoplanet characterization, which allows some amount of the data to have underestimated errorbars. This method compares the photometry on the substellar companion GJ 758b to custom atmospheric models to determine the exoplanet's atmospheric properties. It also demonstrates that some of the data is inconsistent with the models, and produces a probability distribution of atmospheric properties including temperature, gravity, cloud thickness, and chemical abundance for GJ 758b which automatically weights the photometry by the probability that it is correct at each wavelength.
Statistical properties of dwarf novae-type cataclysmic variables: The Outburst Catalogue
Coppejans, Deanne L; Knigge, Christian; Pretorius, Margaretha L; Woudt, Patrick A; Groot, Paul J; Van Eck, Cameron L; Drake, Andrew J
2015-01-01
The Outburst Catalogue contains a wide variety of observational properties for 722 dwarf nova-type (DN) cataclysmic variables (CVs) and 309 CVs of other types from the Catalina Real-time Transient Survey. In particular, it includes the apparent outburst and quiescent V-band magnitudes, duty cycles, limits on the recurrence time, upper- and lower-limits on the distance and absolute quiescent magnitudes, colour information, orbital parameters, and X-ray counterparts. These properties were determined by means of a classification script presented in this paper. The DN in the catalogue show a correlation between the outburst duty cycle and the orbital period (and outburst recurrence time), as well as between the quiescent absolute magnitude and the orbital period (and duty cycle). This is the largest sample of dwarf nova properties collected to date. Besides serving as a useful reference for individual systems and a means of selecting objects for targeted studies, it will prove valuable for statistical studies tha...
Zylberberg, Joel; Pfau, David; Deweese, Michael Robert
2012-12-01
The opacity of typical objects in the world results in occlusion, an important property of natural scenes that makes inference of the full three-dimensional structure of the world challenging. The relationship between occlusion and low-level image statistics has been hotly debated in the literature, and extensive simulations have been used to determine whether occlusion is responsible for the ubiquitously observed power-law power spectra of natural images. To deepen our understanding of this problem, we have analytically computed the two- and four-point functions of a generalized "dead leaves" model of natural images with parameterized object transparency. Surprisingly, transparency alters these functions only by a multiplicative constant, so long as object diameters follow a power-law distribution. For other object size distributions, transparency more substantially affects the low-level image statistics. We propose that the universality of power-law power spectra for both natural scenes and radiological medical images, formed by the transmission of x-rays through partially transparent tissue, stems from power-law object size distributions, independent of object opacity.
Statistical analysis of the acceleration of Baltic mean sea-level rise, 1900-2012
Directory of Open Access Journals (Sweden)
Birgit Hünicke
2016-07-01
Full Text Available We analyse annual mean sea-level records from tide-gauges located in the Baltic and parts of the North Sea with the aim of detecting an acceleration of sea-level rise over the 20textsuperscript{th} and 21textsuperscript{st} centuries. The acceleration is estimated as a (1 fit to a polynomial of order two in time, (2 a long-term linear increase in the rates computed over gliding overlapping decadal time segments, and (3 a long-term increase of the annual increments of sea level.The estimation methods (1 and (2 prove to be more powerful in detecting acceleration when tested with sea-level records produced in global climate model simulations. These methods applied to the Baltic-Sea tide-gauges are, however, not powerful enough to detect a significant acceleration in most of individual records, although most estimated accelerations are positive. This lack of detection of statistically significant acceleration at the individual tide-gauge level can be due to the high-level of local noise and not necessarily to the absence of acceleration.The estimated accelerations tend to be stronger in the north and east of the Baltic Sea. Two hypothesis to explain this spatial pattern have been explored. One is that this pattern reflects the slow-down of the Glacial Isostatic Adjustment. However, a simple estimation of this effect suggests that this slow-down cannot explain the estimated acceleration. The second hypothesis is related to the diminishing sea-ice cover over the 20textsuperscript{th} century. The melting o of less saline and colder sea-ice can lead to changes in sea-level. Also, the melting of sea-ice can reduce the number of missing values in the tide-gauge records in winter, potentially influencing the estimated trends and acceleration of seasonal mean sea-level This hypothesis cannot be ascertained either since the spatial pattern of acceleration computed for winter and summer separately are very similar. The all-station-average-record displays an
Kim, Jeong-Hwan; Kang, Seong-Woo; Kim, Seung-Wook; Chang, Hyo-Ihl
2005-09-01
Medium composition was optimized for high-level production of astaxanthin by Xanthophyllomyces dendrorhous mutant JH1 using statistical experimental designs. Glucose and yeast extract were the most important factors affecting astaxanthin production. Glucose 3.89%, yeast extract 0.29%, KH2PO4 0.25%, MgSO4 0.05%, MnSO4 0.02%, and CaCl2 0.01% were optimum for high-level production of astaxanthin. Under optimized conditions, the maximum concentration of astaxanthin obtained after 7 d of cultivation was 36.06 mg/l. The concentration of astaxanthin predicted by a polynomial model was 36.16 mg/l.
Impacts of land leveling on lowland soil physical properties
Directory of Open Access Journals (Sweden)
José Maria Barbat Parfitt
2014-02-01
Full Text Available The practice of land leveling alters the soil surface to create a uniform slope to improve land conditions for the application of all agricultural practices. The aims of this study were to evaluate the impacts of land leveling through the magnitudes, variances and spatial distributions of selected soil physical properties of a lowland area in the State of Rio Grande do Sul, Brazil; the relationships between the magnitude of cuts and/or fills and soil physical properties after the leveling process; and evaluation of the effect of leveling on the spatial distribution of the top of the B horizon in relation to the soil surface. In the 0-0.20 m layer, a 100-point geo-referenced grid covering two taxonomic soil classes was used in assessment of the following soil properties: soil particle density (Pd and bulk density (Bd; total porosity (Tp, macroporosity (Macro and microporosity (Micro; available water capacity (AWC; sand, silt, clay, and dispersed clay in water (Disp clay contents; electrical conductivity (EC; and weighted average diameter of aggregates (WAD. Soil depth to the top of the B horizon was also measured before leveling. The overall effect of leveling on selected soil physical properties was evaluated by paired "t" tests. The effect on the variability of each property was evaluated through the homogeneity of variance test. The thematic maps constructed by kriging or by the inverse of the square of the distances were visually analyzed to evaluate the effect of leveling on the spatial distribution of the properties and of the top of the B horizon in relation to the soil surface. Linear regression models were fitted with the aim of evaluating the relationship between soil properties and the magnitude of cuts and fills. Leveling altered the mean value of several soil properties and the agronomic effect was negative. The mean values of Bd and Disp clay increased and Tp, Macro and Micro, WAD, AWC and EC decreased. Spatial distributions of all
Energy Technology Data Exchange (ETDEWEB)
Balasubramanian, K
2004-03-17
We have presented a group theoretical analysis of the vibrational modes and rovibronic levels of a novel extended aromatic C{sub 48}N{sub 12} azafullerene. The nuclear spin multiplets and statistical weights of {sup 14}N spin-1 bosons, vibrational and rotational analysis and computed vibrational spectra are provided. We have also predicted the properties of the {sup 3}A{sub u}, {sup 3}E{sub g}, and {sup 3}E{sub u} excited states of C{sub 48}N{sub 12} that lie 1.9 eV above the {sup 1}A{sub g} ground state, and that the {sup 3}E{sub g} and {sup 3}E{sub u} states would undergo Jahn-Teller distortion into chiral structures with no symmetry and an achiral structure with C{sub i} symmetry.
Impact of missing sounding reports on mandatory levels and tropopause statistics: a case study
Directory of Open Access Journals (Sweden)
J. C. Antuña
2006-10-01
Full Text Available This paper describes the effect of missing sounding reports on temperature and pressure mean values for mandatory levels using the aerological information from the Camagüey Meteorological Centre. Also it is described the effect of missing data on mean temperature and pressure values at the multiple tropopause levels. The case study belongs to one station for a time lag of eight years. Up to the present these types of studies have been conducted using simulated datasets. The present one uses a real inhomogeneous radiosonde dataset. The main reason for missing reports were transmission problems and possible encoding-decoding difficulties. It has been found that profiles of the mean temperature and altitude show little differences between the complete and incomplete datasets. Moreover, no statistical significant differences were found for the mean values of the variables for the complete and incomplete datasets. The most probable reason for those results is that the cause of the missing reports has a random behaviour. Finally we have found that the only two effects noticed on the statistics were slightly higher values of the mean temperatures in the complete dataset and the decrease in the percent of multiple tropopause reports for the incomplete dataset.
Probing the statistical properties of unknown texts: application to the Voynich Manuscript.
Amancio, Diego R; Altmann, Eduardo G; Rybski, Diego; Oliveira, Osvaldo N; Costa, Luciano da F
2013-01-01
While the use of statistical physics methods to analyze large corpora has been useful to unveil many patterns in texts, no comprehensive investigation has been performed on the interdependence between syntactic and semantic factors. In this study we propose a framework for determining whether a text (e.g., written in an unknown alphabet) is compatible with a natural language and to which language it could belong. The approach is based on three types of statistical measurements, i.e. obtained from first-order statistics of word properties in a text, from the topology of complex networks representing texts, and from intermittency concepts where text is treated as a time series. Comparative experiments were performed with the New Testament in 15 different languages and with distinct books in English and Portuguese in order to quantify the dependency of the different measurements on the language and on the story being told in the book. The metrics found to be informative in distinguishing real texts from their shuffled versions include assortativity, degree and selectivity of words. As an illustration, we analyze an undeciphered medieval manuscript known as the Voynich Manuscript. We show that it is mostly compatible with natural languages and incompatible with random texts. We also obtain candidates for keywords of the Voynich Manuscript which could be helpful in the effort of deciphering it. Because we were able to identify statistical measurements that are more dependent on the syntax than on the semantics, the framework may also serve for text analysis in language-dependent applications.
Stück, H. L.; Siegesmund, S.
2012-04-01
Sandstones are a popular natural stone due to their wide occurrence and availability. The different applications for these stones have led to an increase in demand. From the viewpoint of conservation and the natural stone industry, an understanding of the material behaviour of this construction material is very important. Sandstones are a highly heterogeneous material. Based on statistical analyses with a sufficiently large dataset, a systematic approach to predicting the material behaviour should be possible. Since the literature already contains a large volume of data concerning the petrographical and petrophysical properties of sandstones, a large dataset could be compiled for the statistical analyses. The aim of this study is to develop constraints on the material behaviour and especially on the weathering behaviour of sandstones. Approximately 300 samples from historical and presently mined natural sandstones in Germany and ones described worldwide were included in the statistical approach. The mineralogical composition and fabric characteristics were determined from detailed thin section analyses and descriptions in the literature. Particular attention was paid to evaluating the compositional and textural maturity, grain contact respectively contact thickness, type of cement, degree of alteration and the intergranular volume. Statistical methods were used to test for normal distributions and calculating the linear regression of the basic petrophysical properties of density, porosity, water uptake as well as the strength. The sandstones were classified into three different pore size distributions and evaluated with the other petrophysical properties. Weathering behavior like hygric swelling and salt loading tests were also included. To identify similarities between individual sandstones or to define groups of specific sandstone types, principle component analysis, cluster analysis and factor analysis were applied. Our results show that composition and porosity
Statistical properties of continuous composite scales and implications for drug development.
Liu-Seifert, Hong; Andersen, Scott; Case, Michael; Sparks, JonDavid; Holdridge, Karen C; Wessels, Alette M; Hendrix, Suzanne; Aisen, Paul; Siemers, Eric
2017-04-12
Little research has been conducted on the statistical properties of composite measures comprising linear combinations of continuous component scales. We assessed the quantitative relationship between the composites and their individual components regarding their abilities to detect treatment effects. In particular, we developed the mathematical derivation of the treatment effect size of a continuous composite in relation to the treatment effect sizes of its components and proved multiple properties of the composite. We demonstrated that the treatment effect size of a composite is greater than the minimum treatment effect size of its components and that above certain thresholds of correlations of components and ratios of component effect sizes, the composite may outperform its components. Examples from Alzheimer's disease (AD) clinical studies of solanezumab and donepezil using the composite Integrated AD Rating Scale (iADRS) and its components, the AD Assessment Scale-Cognitive subscale (ADAS-Cog) and AD Cooperative Study-Activities of Daily Living inventory, instrumental items (ADCS-iADL) were consistent with the theoretical statistical properties. The understanding of the quantitative relationships between continuous composites and their components will be useful in clinical trial design and the development of new scales and composites across therapeutic areas.
Monteiro, Mayra; Oliveira, Victor; Santos, Francisco; Barros Neto, Eduardo; Silva, Karyn; Silva, Rayane; Henrique, João; Chibério, Abimaelle
2017-08-01
In order to obtain cassava starch films with improved mechanical properties in relation to the synthetic polymer in the packaging production, a complete factorial design 23 was carried out in order to investigate which factor significantly influences the tensile strength of the biofilm. The factors to be investigated were cassava starch, glycerol and modified clay contents. Modified bentonite clay was used as a filling material of the biofilm. Glycerol was the plasticizer used to thermoplastify cassava starch. The factorial analysis suggested a regression model capable of predicting the optimal mechanical property of the cassava starch film from the maximization of the tensile strength. The reliability of the regression model was tested by the correlation established with the experimental data through the following statistical analyse: Pareto graph. The modified clay was the factor of greater statistical significance on the observed response variable, being the factor that contributed most to the improvement of the mechanical property of the starch film. The factorial experiments showed that the interaction of glycerol with both modified clay and cassava starch was significant for the reduction of biofilm ductility. Modified clay and cassava starch contributed to the maximization of biofilm ductility, while glycerol contributed to the minimization.
Li, B
1995-01-01
We look at the high-lying eigenstates (from the 10,001st to the 13, 000th) in the Robnik billiard (defined as a quadratic conformal map of the unit disk) with the shape parameter \\lambda=0.15. All the 3,000 eigenstates have been numerically calculated and examined in the configuration space and in the phase space which - in comparison with the classical phase space - enabled a clear cut classification of energy levels into regular and irregular. This is the first successful separation of energy levels based on purely dynamical rather than special geometrical symmetry properties. We calculate the fractional measure of regular levels as \\rho_1=0.365\\pm 0.01 which is in remarkable agreement with the classical estimate \\rho_1=0.360\\pm 0.001. This finding confirms the Percival's (1973) classification scheme, the assumption in Berry-Robnik (1984) theory and the rigorous result by Lazutkin (1981,1991). The regular levels obey the Poissonian statistics quite well whereas the irregular sequence exhibits the fractional...
Multi-scale random sets: from morphology to effective properties and to fracture statistics
Energy Technology Data Exchange (ETDEWEB)
Jeulin, Dominique, E-mail: dominique.jeulin@mines-paristech.fr [Centre de Morphologie Mathematique, Mathematiques et Systemes, Mines ParisTech 35 rue Saint-Honore, F77300 Fontainebleau (France)
2011-09-15
Complex microstructures in materials often involve multi-scale heterogeneous textures, modelled by random sets derived from Mathematical Morphology. Starting from 2D or 3D images, a complete morphological characterization by image analysis is performed, and used for the identification of a model of random structure. From morphological models, simulations of realistic microstructures are introduced in a numerical solver to compute appropriate fields (electric, elastic stress or strain, ...) and to estimate the effective properties by numerical homogenization, accounting for scale dependent statistical fluctuations of the fields. Our approach is illustrated by various examples of multi-scale models: Boolean random sets based on Cox point processes and various random grains (spheres, cylinders), showing a very low percolation threshold, and therefore a high conductivity or high elastic moduli for a low volume fraction of a second phase. Multiscale Cox point processes are also a source of instructive models of fracture statistics, such as multiscale weakest link models.
Statistical properties of aerosol-cloud-precipitation interactions in South America
Directory of Open Access Journals (Sweden)
T. A. Jones
2010-03-01
Full Text Available Given the complex interaction between aerosol, cloud, and atmospheric properties, it is difficult to extract their individual effects to observed rainfall amount. This research uses principle component analysis (PCA that combines Moderate Resolution Imaging Spectroradiometer (MODIS aerosol and cloud products, NCEP Reanalysis atmospheric products, and rainrate estimates from the Tropical Rainfall Measuring Mission (TRMM precipitation radar (PR to assess if aerosols affect warm rain processes. Data collected during September 2006 over the Amazon basin in South America during the biomass-burning season are used. The goal of this research is to combine these observations into a smaller number of variables through PCA with each new variable having a unique physical interpretation. In particular, we are concerned with PC variables whose weightings include aerosol optical thickness (AOT, as these may be an indicator of aerosol indirect effects. If they are indeed occurring, then PC values that include AOT should change as a function of rainrate.
To emphasize the advantage of PCA, changes in aerosol, cloud, and atmospheric observations are compared to rainrate. Comparing no-rain, rain, and heavy rain only (>5 mm h^{−1} samples, we find that cloud thicknesses, humidity, and upward motion are all greater during rain and heavy rain conditions. However, no statistically significant difference in AOT exists between each sample, indicating that atmospheric conditions are more important to rainfall than aerosol concentrations as expected. If aerosols are affecting warm process clouds, it would be expected that stratiform precipitation would decrease as a function increasing aerosol concentration through either Twomey and/or semi-direct effects. PCA extracts the latter signal in a variable labeled PC2, which explains 15% of the total variance and is second in importance the variable (PC1 containing the broad atmospheric conditions. PC2
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Wenchao Cui
2013-01-01
Full Text Available This paper presents a variational level set method for simultaneous segmentation and bias field estimation of medical images with intensity inhomogeneity. In our model, the statistics of image intensities belonging to each different tissue in local regions are characterized by Gaussian distributions with different means and variances. According to maximum a posteriori probability (MAP and Bayes’ rule, we first derive a local objective function for image intensities in a neighborhood around each pixel. Then this local objective function is integrated with respect to the neighborhood center over the entire image domain to give a global criterion. In level set framework, this global criterion defines an energy in terms of the level set functions that represent a partition of the image domain and a bias field that accounts for the intensity inhomogeneity of the image. Therefore, image segmentation and bias field estimation are simultaneously achieved via a level set evolution process. Experimental results for synthetic and real images show desirable performances of our method.
Statistically Based Inference of Physical Rock Properties of Main Rock Types in Germany
Koch, A.; Jorand, R.; Clauser, C.
2009-12-01
A major obstacle for an increased use of geothermal energy often lies in the high success risk for the development of geothermal reservoirs due to the unknown rock properties. In general, the ranges of thermal and hydraulic properties (thermal conductivity, volumetric heat capacity, porosity, permeability) in existing compilations of rock properties are too large to be useful to constrain properties for specific sites. Usually, conservative assumptions are made about these properties, resulting in greater drilling depth and increased exploration cost. In this study, data from direct measurements on more than 600 core samples from different borehole locations and depths enable to derive statistical moments of the desired properties for selected main rock types in the German subsurface. Using modern core scanning technology allowed measuring rapidly thermal conductivity, sonic velocity, and gamma density with high resolution on a large number of samples. In addition, we measured porosity, bulk density, and matrix density based on Archimedes’ principle and pycnometer analysis. Tests on a smaller collection of samples also include specific heat capacity, hydraulic permeability, and radiogenic heat production rate. In addition, we complemented the petrophysical measurements by quantitative mineralogical analysis. The results reveal that even for the same main rock type the results differ significantly depending on geologic age, origin, compaction, and mineralogical composition. For example, water saturated thermal conductivity of tight Palaeozoic sandstones from the Lower Rhine Embayment and the Ruhr Area is 4.0±0.7 W m-1 K-1 and 4.6±0.6 W m-1 K-1, respectively, which is nearly identical to values for the Lower Triassic Bunter sandstone in Southwest-Germany (high in quartz showing an average value of 4.3±0.4 W m-1 K-1). In contrast, saturated thermal conductivity of Upper Triassic sandstone in the same area is considerably lower at 2.5±0.1 W m-1 K-1 (Schilf
Directory of Open Access Journals (Sweden)
Athanasios G. Lazaropoulos
2012-01-01
Full Text Available This paper considers broadband signal transmission and statistical performance properties of high-voltage/broadband over power lines (HV/BPL channels associated with overhead power transmission. The overhead HV/BPL transmission channel is investigated with regard to its spectral behavior, its end-to-end signal attenuation, and its statistical performance metrics. It is found that the above features depend critically on the frequency, the overhead HV power grid type (150 kV, 275 kV, or 400 kV and single- or double-circuit, the coupling scheme applied, the physical properties of the cables used, the MTL configuration, and the type of branches existing along the end-to-end BPL signal propagation. The contribution of this paper is threefold. First, the significant broadband transmission potential of overhead HV lines is revealed. The results demonstrate that, regardless of overhead HV power grid type, the overhead HV grid is a potentially excellent communications medium, offering low-loss characteristics, flat-fading features, and low multipath dispersion over a 25 km repeater span well beyond 100 MHz. Second, regarding the statistical properties of various overhead HV/BPL transmission channels, two fundamental correlations of several wireline systems, for example, coaxial cables and xDSL, are also validated in the case of overhead HV/BPL transmission channels, namely, (i end-to-end channel attenuation in relation with root-mean-square delay spread (RMS-DS and (ii coherence bandwidth (CB in relation with RMS-DS. Third, fitting the numerical results and other field trial measurements, two regression distributions suitable for each fundamental correlation are proposed.
Statistical analysis of interaction between lake seepage rates and groundwater and lake levels
Ala-aho, P.; Rossi, P. M.; Klöve, B.
2012-04-01
In Finland, the main sources of groundwater are the esker deposits from the last ice age. Small lakes imbedded in the aquifer with no outlets or inlets are typically found in eskers. Some lakes at Rokua esker, in Northern Finland, have been suffering from changes in water stage and quality. A possible permanent decline of water level has raised considerable concern as the area is also used for recreation and tourism. Rare biotypes supported by the oligotrophic lakes can also be endangered by the level decline. Drainage of peatlands located in the discharge zone of the aquifer is a possible threat for the lakes and the whole aquifer. Drainage can potentially lower the aquifer water table which can have an effect on the groundwater-lake interaction. The aim of this study was to understand in more detail the interaction of the aquifer and the lake systems so potential causes for the lake level variations could be better understood and managed. In-depth understanding of hydrogeological system provides foundation to study the nutrient input to lakes affecting lake ecosystems. A small lake imbedded the Rokua esker aquifer was studied in detail. Direct measurements of seepage rate between the lake and the aquifer were carried out using seepage meters. Seepage was measured from six locations for eight times during May 2010 - November 2010. Precipitation was recorded with a tipping bucket rain gauge adjacent to the lake. Lake stage and groundwater levels from three piezometers were registered on an hourly interval using pressure probes. Statistical methods were applied to examine relationship between seepage measurements and levels of lake and groundwater and amount of precipitation. Distinct areas of inseepage and outseepage of the lake were distinguished with seepage meter measurements. Seepage rates showed only little variation within individual measurement locations. Nevertheless analysis revealed statistically significant correlation of seepage rate variation in four
Crane, R. K.
1975-01-01
An experiment was conducted to study the relations between the empirical distribution functions of reflectivity at specified locations above the surface and the corresponding functions at the surface. A bistatic radar system was used to measure continuously the scattering cross section per unit volume at heights of 3 and 6 km. A frequency of 3.7 GHz was used in the tests. It was found that the distribution functions for reflectivity may significantly change with height at heights below the level of the melting layer.
Quantum Statistical Properties of the Exciton in a Leaky Quasi-Mode Cavity
Institute of Scientific and Technical Information of China (English)
YU Zhao-Xian; JIAO Zhi-Yong
2002-01-01
We have studied quantum statistical properties of the exciton in a leaky quasi-mode cavity. It is shown that when the exciton is initially in a squeezed coherent state whereas cavity initially in a vacuum state, there is energy exchange between the exciton and cavity. Both the exciton and cavity may exhibit sub-Poissonian distribution and exist quadrature squeezing. Calculation shows that correlation between the exciton and cavity is classical, which implies that there is not the violation of the Cauchy-Schwartz inequality.
Application of Maximum Entropy Distribution to the Statistical Properties of Wave Groups
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The new distributions of the statistics of wave groups based on the maximum entropy principle are presented. The maximum entropy distributions appear to be superior to conventional distributions when applied to a limited amount of information. Its applications to the wave group properties show the effectiveness of the maximum entropy distribution. FFT filtering method is employed to obtain the wave envelope fast and efficiently. Comparisons of both the maximum entropy distribution and the distribution of Longuet-Higgins (1984) with the laboratory wind-wave data show that the former gives a better fit.
Kirchner, Jens; Meyer, Wolfgang; Elsholz, Markus; Hensel, Bernhard
2007-08-01
Using the Langevin equation we develop the model of a stochastic process subject to a given time-dependent regulatory mechanism. The effects of this nonstationarity on the statistical properties of the time series, i.e., on global and conditional probability densities and on the moments of the distribution, are derived. Application of these results on simple model trends allows one to approximate cardiological data and thus to explain effects recently observed in the reconstruction of the deterministic part of the Langevin equation for time series of heart rate.
A new type of photon-added squeezed coherent state and its statistical properties
Institute of Scientific and Technical Information of China (English)
Zhou Jun; Fan Hong-Yi; Song Jun
2012-01-01
We construct a new type of photon-added squeezed coherent state generated by repeatedly operating the bosonic creation operator on a new type of squeezed coherent state [Fan H Y and Xiao M 1996 Phys.Lett.A 220 81].We find that its normalization factor is related to single-variable Hermite polynomials.Furthermore,we investigate its statistical properties,such as Mandel's Q parameter,photon-number distribution,and Wigner function.The nonclassicality is displayed in terms of the intense oscillation of photon-number distribution and the negativity of the Wigner function.
Statistical Properties of a Ring Laser with Injected Signal and Backscattering
Institute of Scientific and Technical Information of China (English)
LENG Feng; ZHU Shi-Qun
2001-01-01
The statistical properties of a homogeneously broadened ring laser with an injected signal are investigated and the normalized two-mode intensity auto- and cross-correlation functions are calculated by a full saturation laser theory with backscattering. The theoretical predictions are in good agreement with the experimental measurements.Further investigation reveals that the backscattering can reduce the fluctuations in the system while the full saturation effect plays a major role when the laser is operated above threshold. It is also quite important to notice that the injected signal can drive the weak mode from incoherent light to coherent light.``
Statistical Properties of Inter-arrival Times Distribution in Social Tagging Systems
Capocci, Andrea; Servedio, Vito D P; Loreto, Vittorio
2012-01-01
Folksonomies provide a rich source of data to study social patterns taking place on the World Wide Web. Here we study the temporal patterns of users' tagging activity. We show that the statistical properties of inter-arrival times between subsequent tagging events cannot be explained without taking into account correlation in users' behaviors. This shows that social interaction in collaborative tagging communities shapes the evolution of folksonomies. A consensus formation process involving the usage of a small number of tags for a given resources is observed through a numerical and analytical analysis of some well-known folksonomy datasets.
Sea-level probability for the last deglaciation: A statistical analysis of far-field records
Stanford, J. D.; Hemingway, R.; Rohling, E. J.; Challenor, P. G.; Medina-Elizalde, M.; Lester, A. J.
2011-12-01
Pulses of ice-sheet meltwater into the world ocean during the last deglaciation are of great current interest, because these large-scale events offer important test-beds for numerical models of the responses of ocean circulation and climate to meltwater addition. The largest such event has become known as meltwater pulse (mwp) 1a, with estimates of about 20 m of sea-level rise in about 500 years. A second meltwater pulse (mwp-1b) has been inferred from some sea-level records, but its existence has become debated following the presentation of additional records. Even the use of the more ubiquitous mwp-1a in modelling studies has been compromised by debate about its exact age, based upon perceived discrepancies between far-field sea-level records. It is clear that an objective investigation is needed to determine to what level inferred similarities and/or discrepancies between the various deglacial sea-level records are statistically rigorous (or not). For that purpose, we present a Monte Carlo style statistical analysis to determine the highest-probability sea-level history from six key far-field deglacial sea-level records, which fully accounts for realistic methodological and chronological uncertainties in all these records, and which is robust with respect to removal of individual component datasets. We find that sea-level rise started to accelerate into the deglaciation from around 17 ka BP. Within the deglacial rise, there were two distinct increases; one at around the timing of the Bølling warming (14.6 ka BP), and another, much broader, event that just post-dates the end of the Younger Dryas (11.3 ka BP). We interpret these as mwp-1a and mwp-1b, respectively. We find that mwp-1a occurred between 14.3 ka BP and 12.8 ka BP. Highest rates of sea-level rise occurred at ~ 13.8 ka, probably (67% confidence) within the range of 100-130 cm/century, although values may have been as high as 260 cm/century (99% confidence limit). Mwp-1b is robustly expressed as a broad
Directory of Open Access Journals (Sweden)
Song Fujian
2012-09-01
Full Text Available Abstract Background Indirect treatment comparison (ITC and mixed treatment comparisons (MTC have been increasingly used in network meta-analyses. This simulation study comprehensively investigated statistical properties and performances of commonly used ITC and MTC methods, including simple ITC (the Bucher method, frequentist and Bayesian MTC methods. Methods A simple network of three sets of two-arm trials with a closed loop was simulated. Different simulation scenarios were based on different number of trials, assumed treatment effects, extent of heterogeneity, bias and inconsistency. The performance of the ITC and MTC methods was measured by the type I error, statistical power, observed bias and mean squared error (MSE. Results When there are no biases in primary studies, all ITC and MTC methods investigated are on average unbiased. Depending on the extent and direction of biases in different sets of studies, ITC and MTC methods may be more or less biased than direct treatment comparisons (DTC. Of the methods investigated, the simple ITC method has the largest mean squared error (MSE. The DTC is superior to the ITC in terms of statistical power and MSE. Under the simulated circumstances in which there are no systematic biases and inconsistencies, the performances of MTC methods are generally better than the performance of the corresponding DTC methods. For inconsistency detection in network meta-analysis, the methods evaluated are on average unbiased. The statistical power of commonly used methods for detecting inconsistency is very low. Conclusions The available methods for indirect and mixed treatment comparisons have different advantages and limitations, depending on whether data analysed satisfies underlying assumptions. To choose the most valid statistical methods for research synthesis, an appropriate assessment of primary studies included in evidence network is required.
The statistical decay properties of Gadolinium isotopes using the DANCE array
Dashdorj, D.; Mitchell, G.; Baramsai, B.; Chankova, R.; Chyzh, A.; Walker, C.
2008-10-01
The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. There are seven stable isotopes of gadolinium with varying deformation. Decay γ rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight path 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable γ-ray multiplicity measurements. The calorimetric property of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles γ-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei.
Energy Technology Data Exchange (ETDEWEB)
Belianinov, Alex, E-mail: belianinova@ornl.gov; Ganesh, Panchapakesan; Lin, Wenzhi; Jesse, Stephen; Pan, Minghu; Kalinin, Sergei V. [Oak Ridge National Laboratory, Institute for Functional Imaging of Materials, Center for Nanophase Material Science, Oak Ridge, Tennessee 37922 (United States); Sales, Brian C.; Sefat, Athena S. [Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, Tennessee 37922 (United States)
2014-12-01
Atomic level spatial variability of electronic structure in Fe-based superconductor FeTe{sub 0.55}Se{sub 0.45} (T{sub c} = 15 K) is explored using current-imaging tunneling-spectroscopy. Multivariate statistical analysis of the data differentiates regions of dissimilar electronic behavior that can be identified with the segregation of chalcogen atoms, as well as boundaries between terminations and near neighbor interactions. Subsequent clustering analysis allows identification of the spatial localization of these dissimilar regions. Similar statistical analysis of modeled calculated density of states of chemically inhomogeneous FeTe{sub 1−x}Se{sub x} structures further confirms that the two types of chalcogens, i.e., Te and Se, can be identified by their electronic signature and differentiated by their local chemical environment. This approach allows detailed chemical discrimination of the scanning tunneling microscopy data including separation of atomic identities, proximity, and local configuration effects and can be universally applicable to chemically and electronically inhomogeneous surfaces.
The physical statistics analysis of the contributing factors of the low level clouds development
Huseynov, N. Sh.; Malikov, B. M.
2009-04-01
In this article studying of conditions of low level clouds development and applicability of individual predictive factors in prognostic models are considered. In this purposes advective variations of temperature (A), radius of isobars (R), ground pressure Laplasian (P ), horizontal gradient of air pressure (grad P) are calculated. It is shown, that the consideration of advective variations of temperature and humidity, radius of curvature of isobars, ground pressure Laplasian and a vertical movements allows to survey conditions of low clouds development comprehensively. At presence of clouds main values of advective variations of temperature during cold and warm air advections were -0.630Ch and 0.530Ch appropriately. At the above stated conditions main values of advective variation of a dew-point was -0.500Ch and 0.620Ch. At the absence of low clouds main advective variations of temperature and dew-point were -0.150Ch for cold air advection, and -0.030Ch for warm air advection. References: Bruks K., Karuzers N.: Application of statistics in meteorology. Hydrometizdat, 416 pp., Leningrad, 1963. Gruza G.V., Rankova E.Y.: The structural changes of up to date climate // Meteorology and Hydrology, vol. #7, 14-18, Moscow, 1990. Panofsky G.A., Brayer G.V.: Statistical methods in meteorology. Hydrometizdat, 209 pp., Leningrad, 1977.
Bogdanov, Yu I; Gavrichenko, A K
2011-01-01
A throughout study of statistical characteristics of fidelity in different protocols of quantum tomography is given. We consider protocols based on geometry of platonic solids and other polyhedrons with high degree of symmetry such as fullerene and its dual polyhedron. Characteristics of fidelity in different protocols are compared to the theoretical level of the minimum possible level of fidelity loss. Tomography of pure and mixed states in Hilbert spaces of different dimension is analyzed. Results of this work could be used for a better control of quantum gates and quantum states in quantum information technologies.
Breast cancer diagnosis using level-set statistics and support vector machines.
Liu, Jianguo; Yuan, Xiaohui; Buckles, Bill P
2008-01-01
Breast cancer diagnosis based on microscopic biopsy images and machine learning has demonstrated great promise in the past two decades. Various feature selection (or extraction) and classification algorithms have been attempted with success. However, some feature selection processes are complex and the number of features used can be quite large. We propose a new feature selection method based on level-set statistics. This procedure is simple and, when used with support vector machines (SVM), only a small number of features is needed to achieve satisfactory accuracy that is comparable to those using more sophisticated features. Therefore, the classification can be completed in much shorter time. We use multi-class support vector machines as the classification tool. Numerical results are reported to support the viability of this new procedure.
Level statistics of words: finding keywords in literary texts and symbolic sequences.
Carpena, P; Bernaola-Galván, P; Hackenberg, M; Coronado, A V; Oliver, J L
2009-03-01
Using a generalization of the level statistics analysis of quantum disordered systems, we present an approach able to extract automatically keywords in literary texts. Our approach takes into account not only the frequencies of the words present in the text but also their spatial distribution along the text, and is based on the fact that relevant words are significantly clustered (i.e., they self-attract each other), while irrelevant words are distributed randomly in the text. Since a reference corpus is not needed, our approach is especially suitable for single documents for which no a priori information is available. In addition, we show that our method works also in generic symbolic sequences (continuous texts without spaces), thus suggesting its general applicability.
Zooming in on local level statistics by supersymmetric extension of free probability
Energy Technology Data Exchange (ETDEWEB)
Zirnbauer, S Mandt and M R [Institut fuer Theoretische Physik, Universitaet zu Koeln, Zuelpicher Strasse 77, 50937 Koeln (Germany)], E-mail: zirnbauer@uni-koeln.de
2010-01-15
We consider unitary ensembles of Hermitian N x N matrices governed by a confining potential NV with analytic and uniformly convex V. From earlier work it is known that the large-N limit of the characteristic function for a finite-rank Fourier variable K is determined by the Voiculescu R-transform, a key object in free probability theory. Going beyond these results, we argue that the same holds true when the finite-rank operator K has the form that is required by the Wegner-Efetov supersymmetry method. This insight leads to a potent new technique for the study of local statistics, e.g. level correlations. We illustrate the new technique by demonstrating universality in a random matrix model of stochastic scatteri0008.
Statistics of scattered photons from a driven three-level emitter in 1D open space
Energy Technology Data Exchange (ETDEWEB)
Roy, Dibyendu [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). Theoretical Div. and Center for Nonlinear Studies; Bondyopadhaya, Nilanjan [Visva-Bharati University, Santiniketan (India). Integrated Science Education and Research Centre
2014-01-07
We derive the statistics of scattered photons from a Λ- or ladder-type three-level emitter (3LE) embedded in a 1D open waveguide. The weak probe photons in the waveguide are coupled to one of the two allowed transitions of the 3LE, and the other transition is driven by a control beam. This system shows electromagnetically induced transparency (EIT) which is accompanied with the Autler-Townes splitting (ATS) at a strong driving by the control beam, and some of these effects have been observed recently. We show that the nature of second-order coherence of the transmitted probe photons near two-photon resonance changes from bunching to antibunching to constant as strength of the control beam is ramped up from zero to a higher value where the ATS appears.
Protein logic: a statistical mechanical study of signal integration at the single-molecule level.
de Ronde, Wiet; Rein ten Wolde, Pieter; Mugler, Andrew
2012-09-05
Information processing and decision-making is based upon logic operations, which in cellular networks has been well characterized at the level of transcription. In recent years, however, both experimentalists and theorists have begun to appreciate that cellular decision-making can also be performed at the level of a single protein, giving rise to the notion of protein logic. Here we systematically explore protein logic using a well-known statistical mechanical model. As an example system, we focus on receptors that bind either one or two ligands, and their associated dimers. Notably, we find that a single heterodimer can realize any of the 16 possible logic gates, including the XOR gate, by variation of biochemical parameters. We then introduce what to our knowledge is a novel idea: that a set of receptors with fixed parameters can encode functionally unique logic gates simply by forming different dimeric combinations. An exhaustive search reveals that the simplest set of receptors (two single-ligand receptors and one double-ligand receptor) can realize several different groups of three unique gates, a result for which the parametric analysis of single receptors and dimers provides a clear interpretation. Both results underscore the surprising functional freedom readily available to cells at the single-protein level. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.
Level statistics of disordered spin-1/2 systems and materials with localized Cooper pairs.
Cuevas, Emilio; Feigel'man, Mikhail; Ioffe, Lev; Mezard, Marc
2012-01-01
The origin of continuous energy spectra in large disordered interacting quantum systems is one of the key unsolved problems in quantum physics. Although small quantum systems with discrete energy levels are noiseless and stay coherent forever in the absence of any coupling to external world, most large-scale quantum systems are able to produce a thermal bath and excitation decay. This intrinsic decoherence is manifested by a broadening of energy levels, which aquire a finite width. The important question is: what is the driving force and the mechanism of transition(s) between these two types of many-body systems - with and without intrinsic decoherence? Here we address this question via the numerical study of energy-level statistics of a system of interacting spin-1/2 with random transverse fields. We present the first evidence for a well-defined quantum phase transition between domains of discrete and continous many-body spectra in such spin models, implying the appearance of novel insulating phases in the vicinity of the superconductor-insulator transition in InO(x) and similar materials.
Sea Surface Height Variability and Eddy Statistical Properties in the Red Sea
Zhan, Peng
2013-05-01
Satellite sea surface height (SSH) data over 1992-2012 are analyzed to study the spatial and temporal variability of sea level in the Red Sea. Empirical orthogonal functions (EOF) analysis suggests the remarkable seasonality of SSH in the Red Sea, and a significant correlation is found between SSH variation and seasonal wind cycle. A winding-angle based eddy identification algorithm is employed to derive the mesoscale eddy information from SSH data. Totally more than 5500 eddies are detected, belonging to 2583 eddy tracks. Statistics suggest that eddies generate over the entire Red Sea, with two regions in the central basin of high eddy frequency. 76% of the detected eddies have a radius ranging from 40km to 100km, of which both intensity and absolute vorticity decrease with eddy radius. The average eddy lifespan is about 5 weeks, and eddies with longer lifespan tend to have larger radius but less intensity. Different deformation rate exists between anticyclonic eddies (AEs) and cyclonic eddies (CEs), those eddies with higher intensity appear to be less deformed and more circular. Inspection of the 84 long-lived eddies suggests the AEs tend to move a little more northward than CEs. AE generation during summer is obviously lower than that during other seasons, while CE generation is higher during spring and summer. Other features of AEs and CEs are similar with both vorticity and intensity reaching the summer peaks in August and winter peaks in January. Inter-annual variability reveals that the eddies in the Red Sea are isolated from the global event. The eddy property tendencies are different from the south and north basin, both of which exhibit a two-year cycle. Showing a correlation coefficient of -0.91, Brunt–Väisälä frequency is negatively correlated with eddy kinetic energy (EKE), which results from AE activities in the high eddy frequency region. Climatological vertical velocity shear variation is identical with EKE except in the autumn, suggesting the
A Statistical Summary of Particle Properties in the Cortez Pass in March, 2006
Gomez, L.; Baumgardner, D.; Grutter, M.
2007-05-01
A large suite of instruments for measuring the physical (number and size), optical (scattering and absorption coefficients) and chemical (inorganic and organic composition and hygroscopicity) properties of particles was operated 24 hours a day, seven days a week in the Cortez Pass, 60 km southeast of Mexico City, on the Altzomoni ridge at an altitude of 4010 m ASL. During the night and early morning, the site is in the free troposphere; however, air from the surrounding basins of Mexico City (to the NW), Cuernavaca (SW) and Puebla (SE) rises as the boundary layer in these regions grow as a result of local heating and eventually the measurement site is within the air that comes from one of these regions. This presentation is a statistical summary of particle properties stratified by the air mass origin and, in addition, whether the measurement site was in or out of the free troposphere. The properties with highest correlation are shown along with frequency distributions and relevant time series. The objective of this summary is to offer researchers a quick look at the most significant trends, correlations, means and variances of the particle properties.
A Statistics-Based Material Property Analysis to Support TPS Characterization
Copeland, Sean R.; Cozmuta, Ioana; Alonso, Juan J.
2012-01-01
Accurate characterization of entry capsule heat shield material properties is a critical component in modeling and simulating Thermal Protection System (TPS) response in a prescribed aerothermal environment. The thermal decomposition of the TPS material during the pyrolysis and charring processes is poorly characterized and typically results in large uncertainties in material properties as inputs for ablation models. These material property uncertainties contribute to large design margins on flight systems and cloud re- construction efforts for data collected during flight and ground testing, making revision to existing models for entry systems more challenging. The analysis presented in this work quantifies how material property uncertainties propagate through an ablation model and guides an experimental test regimen aimed at reducing these uncertainties and characterizing the dependencies between properties in the virgin and charred states for a Phenolic Impregnated Carbon Ablator (PICA) based TPS. A sensitivity analysis identifies how the high-fidelity model behaves in the expected flight environment, while a Monte Carlo based uncertainty propagation strategy is used to quantify the expected spread in the in-depth temperature response of the TPS. An examination of how perturbations to the input probability density functions affect output temperature statistics is accomplished using a Kriging response surface of the high-fidelity model. Simulations are based on capsule configuration and aerothermal environments expected during the Mars Science Laboratory (MSL) entry sequence. We identify and rank primary sources of uncertainty from material properties in a flight-relevant environment, show the dependence on spatial orientation and in-depth location on those uncertainty contributors, and quantify how sensitive the expected results are.
Han, Kuk-Il; Kim, Do-Hwi; Choi, Jun-Hyuk; Kim, Tae-Kuk; Shin, Jong-Jin
2016-09-01
Infrared signals are widely used to discriminate objects against the background. Prediction of infrared signal from an object surface is essential in evaluating the detectability of the object. Appropriate and easy method of procurement of the radiative properties such as the surface emissivity, bidirectional reflectivity is important in estimating infrared signals. Direct measurement can be a good choice but a costly and time consuming way of obtaining the radiative properties for surfaces coated with many different newly developed paints. Especially measurement of the bidirectional reflectivity usually expressed by the bidirectional reflectance distribution function (BRDF) is the most costly job. In this paper we are presenting an inverse estimation method of the radiative properties by using the directional radiances from the surface of concern. The inverse estimation method used in this study is the statistical repulsive particle swarm optimization (RPSO) algorithm which uses the randomly picked directional radiance data emitted and reflected from the surface. In this paper, we test the proposed inverse method by considering the radiation from a steel plate surface coated with different paints at a clear sunny day condition. For convenience, the directional radiance data from the steel plate within a spectral band of concern are obtained from the simulation using the commercial software, RadthermIR, instead of the field measurement. A widely used BRDF model called as the Sandford-Robertson(S-R) model is considered and the RPSO process is then used to find the best fitted model parameters for the S-R model. The results obtained from this study show an excellent agreement with the reference property data used for the simulation for directional radiances. The proposed process can be a useful way of obtaining the radiative properties from field measured directional radiance data for surfaces coated with or without various kinds of paints of unknown radiative
Capar, M. Ilk; Nar, A.; Ferrarini, A.; Frezza, E.; Greco, C.; Zakharov, A. V.; Vakulenko, A. A.
2013-03-01
The connection between the molecular structure of liquid crystals and their elastic properties, which control the director deformations relevant for electro-optic applications, remains a challenging objective for theories and computations. Here, we compare two methods that have been proposed to this purpose, both characterized by a detailed molecular level description. One is an integrated molecular dynamics-statistical mechanical approach, where the bulk elastic constants of nematics are calculated from the direct correlation function (DCFs) and the single molecule orientational distribution function [D. A. McQuarrie, Statistical Mechanics (Harper & Row, New York, 1973)]. The latter is obtained from atomistic molecular dynamics trajectories, together with the radial distribution function, from which the DCF is then determined by solving the Ornstein-Zernike equation. The other approach is based on a molecular field theory, where the potential of mean torque experienced by a mesogen in the liquid crystal phase is parameterized according to its molecular surface. In this case, the calculation of elastic constants is combined with the Monte Carlo sampling of single molecule conformations. Using these different approaches, but the same description, at the level of molecular geometry and torsional potentials, we have investigated the elastic properties of the nematic phase of two typical mesogens, 4'-n-pentyloxy-4-cyanobiphenyl and 4'-n-heptyloxy-4-cyanobiphenyl. Both methods yield K3(bend) >K1 (splay) >K2 (twist), although there are some discrepancies in the average elastic constants and in their anisotropy. These are interpreted in terms of the different approximations and the different ways of accounting for the structural properties of molecules in the two approaches. In general, the results point to the role of the molecular shape, which is modulated by the conformational freedom and cannot be fully accounted for by a single descriptor such as the aspect ratio.
Giommi, P; Padovani, P
1999-01-01
We have assembled a multi-frequency database by cross-correlating the NVSS catalog of radio sources with the RASSBSC list of soft X-ray sources, obtaining optical magnitude estimates from the Palomar and UK Schmidt surveys as provided by the APM and COSMOS on-line services. By exploiting the nearly unique broad-band properties of High-Energy Peaked (HBL) BL Lacs we have statistically identified a sample of 218 objects that is expected to include about 85% of BL Lacs and that is therefore several times larger than all other published samples of HBLs. Using a subset (155 objects) that is radio flux limited and statistically well-defined we have derived the \\vovm distribution and the LogN-LogS of extreme HBLs (fx/fr >= 3E-10 erg/cm2/s/Jansky) down to 3.5 mJy. We find that the LogN-LogS flattens around 20 mJy and that = 0.42 +/- 0.02. This extends to the radio band earlier results, based on much smaller X-ray selected samples, about the anomalous cosmological observational properties of HBL BL Lacs. A comparison...
Statistical investigation and thermal properties for a 1-D impact system with dissipation
Energy Technology Data Exchange (ETDEWEB)
Díaz I, Gabriel, E-mail: gabriel.diaz.iturry@gmail.com; Livorati, André L.P., E-mail: livorati@rc.unesp.br; Leonel, Edson D., E-mail: edleonel@rc.unesp.br
2016-05-06
Highlights: • The dynamics of a 1-D dissipative impact system is studied. • Statistical properties for the average velocity, root mean square velocity and its deviation are characterized. • A thermodynamics formalism is developed as function of the statistical variable. • The formalism shows itself to be robust, and we can predict numerical values without doing numerical simulations. - Abstract: The behavior of the average velocity, its deviation and average squared velocity are characterized using three techniques for a 1-D dissipative impact system. The system – a particle, or an ensemble of non-interacting particles, moving in a constant gravitation field and colliding with a varying platform – is described by a nonlinear mapping. The average squared velocity allows to describe the temperature for an ensemble of particles as a function of the parameters using: (i) straightforward numerical simulations; (ii) analytically from the dynamical equations; (iii) using the probability distribution function. Comparing analytical and numerical results for the three techniques, one can check the robustness of the developed formalism, where we are able to estimate numerical values for the statistical variables, without doing extensive numerical simulations. Also, extension to other dynamical systems is immediate, including time dependent billiards.
Institute of Scientific and Technical Information of China (English)
DAI Fushan; YU Rucong; ZHANG Xuehong; YU Yongqiang
2005-01-01
In this study, a statistical cloud scheme is first introduced and coupled with a first-order turbulence scheme with second-order turbulence moments parameterized by the timescale of the turbulence dissipation and the vertical turbulent diffusion coefficient. Then the ability of the scheme to simulate cloud fraction at different relative humidity, vertical temperature profile, and the timescale of the turbulent dissipation is examined by numerical simulation. It is found that the simulated cloud fraction is sensitive to the parameter used in the statistical cloud scheme and the timescale of the turbulent dissipation. Based on the analyses, the introduced statistical cloud scheme is modified. By combining the modified statistical cloud scheme with a boundary layer cumulus scheme, a new statistically-based low-level cloud scheme is proposed and tentatively applied in NCAR (National Center for Atmospheric Research) CCM3 (Community Climate Model version3). It is found that the simulation of low-level cloud fraction is markedly improved and the centers with maximum low-level cloud fractions are well simulated in the cold oceans off the western coasts with the statistically-based low-level cloud scheme applied in CCM3. It suggests that the new statistically-based low-level cloud scheme has a great potential in the general circulation model for improving the low-level cloud parameterization.
Local dependence in random graph models: characterization, properties and statistical inference.
Schweinberger, Michael; Handcock, Mark S
2015-06-01
Dependent phenomena, such as relational, spatial and temporal phenomena, tend to be characterized by local dependence in the sense that units which are close in a well-defined sense are dependent. In contrast with spatial and temporal phenomena, though, relational phenomena tend to lack a natural neighbourhood structure in the sense that it is unknown which units are close and thus dependent. Owing to the challenge of characterizing local dependence and constructing random graph models with local dependence, many conventional exponential family random graph models induce strong dependence and are not amenable to statistical inference. We take first steps to characterize local dependence in random graph models, inspired by the notion of finite neighbourhoods in spatial statistics and M-dependence in time series, and we show that local dependence endows random graph models with desirable properties which make them amenable to statistical inference. We show that random graph models with local dependence satisfy a natural domain consistency condition which every model should satisfy, but conventional exponential family random graph models do not satisfy. In addition, we establish a central limit theorem for random graph models with local dependence, which suggests that random graph models with local dependence are amenable to statistical inference. We discuss how random graph models with local dependence can be constructed by exploiting either observed or unobserved neighbourhood structure. In the absence of observed neighbourhood structure, we take a Bayesian view and express the uncertainty about the neighbourhood structure by specifying a prior on a set of suitable neighbourhood structures. We present simulation results and applications to two real world networks with 'ground truth'.
Probing the statistical properties of unknown texts: application to the Voynich Manuscript.
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Diego R Amancio
Full Text Available While the use of statistical physics methods to analyze large corpora has been useful to unveil many patterns in texts, no comprehensive investigation has been performed on the interdependence between syntactic and semantic factors. In this study we propose a framework for determining whether a text (e.g., written in an unknown alphabet is compatible with a natural language and to which language it could belong. The approach is based on three types of statistical measurements, i.e. obtained from first-order statistics of word properties in a text, from the topology of complex networks representing texts, and from intermittency concepts where text is treated as a time series. Comparative experiments were performed with the New Testament in 15 different languages and with distinct books in English and Portuguese in order to quantify the dependency of the different measurements on the language and on the story being told in the book. The metrics found to be informative in distinguishing real texts from their shuffled versions include assortativity, degree and selectivity of words. As an illustration, we analyze an undeciphered medieval manuscript known as the Voynich Manuscript. We show that it is mostly compatible with natural languages and incompatible with random texts. We also obtain candidates for keywords of the Voynich Manuscript which could be helpful in the effort of deciphering it. Because we were able to identify statistical measurements that are more dependent on the syntax than on the semantics, the framework may also serve for text analysis in language-dependent applications.
Statistical analysis to assess automated level of suspicion scoring methods in breast ultrasound
Galperin, Michael
2003-05-01
A well-defined rule-based system has been developed for scoring 0-5 the Level of Suspicion (LOS) based on qualitative lexicon describing the ultrasound appearance of breast lesion. The purposes of the research are to asses and select one of the automated LOS scoring quantitative methods developed during preliminary studies in benign biopsies reduction. The study has used Computer Aided Imaging System (CAIS) to improve the uniformity and accuracy of applying the LOS scheme by automatically detecting, analyzing and comparing breast masses. The overall goal is to reduce biopsies on the masses with lower levels of suspicion, rather that increasing the accuracy of diagnosis of cancers (will require biopsy anyway). On complex cysts and fibroadenoma cases experienced radiologists were up to 50% less certain in true negatives than CAIS. Full correlation analysis was applied to determine which of the proposed LOS quantification methods serves CAIS accuracy the best. This paper presents current results of applying statistical analysis for automated LOS scoring quantification for breast masses with known biopsy results. It was found that First Order Ranking method yielded most the accurate results. The CAIS system (Image Companion, Data Companion software) is developed by Almen Laboratories and was used to achieve the results.
Haberman, Shelby J.
2004-01-01
Statistical and measurement properties are examined for features used in essay assessment to determine the generalizability of the features across populations, prompts, and individuals. Data are employed from TOEFL® and GMAT® examinations and from writing for Criterion?.
Christian Helmers; Mark Rogers
2011-01-01
This paper provides an overview of a new database that contains intellectual property data - in the form of patents and trademarks - for the population of firms registered in the UK. The paper discusses the principal challenges involved in the construction of this integrated database and provides an explanation of the approach taken to address these issues. We employ the integrated dataset to provide descriptive evidence on the firm-level use of intellectual property - including patents and t...
A statistical approach to evaluate flood risk at the regional level: an application to Italy
Rossi, Mauro; Marchesini, Ivan; Salvati, Paola; Donnini, Marco; Guzzetti, Fausto; Sterlacchini, Simone; Zazzeri, Marco; Bonazzi, Alessandro; Carlesi, Andrea
2016-04-01
Floods are frequent and widespread in Italy, causing every year multiple fatalities and extensive damages to public and private structures. A pre-requisite for the development of mitigation schemes, including financial instruments such as insurance, is the ability to quantify their costs starting from the estimation of the underlying flood hazard. However, comprehensive and coherent information on flood prone areas, and estimates on the frequency and intensity of flood events, are not often available at scales appropriate for risk pooling and diversification. In Italy, River Basins Hydrogeological Plans (PAI), prepared by basin administrations, are the basic descriptive, regulatory, technical and operational tools for environmental planning in flood prone areas. Nevertheless, such plans do not cover the entire Italian territory, having significant gaps along the minor hydrographic network and in ungauged basins. Several process-based modelling approaches have been used by different basin administrations for the flood hazard assessment, resulting in an inhomogeneous hazard zonation of the territory. As a result, flood hazard assessments expected and damage estimations across the different Italian basin administrations are not always coherent. To overcome these limitations, we propose a simplified multivariate statistical approach for the regional flood hazard zonation coupled with a flood impact model. This modelling approach has been applied in different Italian basin administrations, allowing a preliminary but coherent and comparable estimation of the flood hazard and the relative impact. Model performances are evaluated comparing the predicted flood prone areas with the corresponding PAI zonation. The proposed approach will provide standardized information (following the EU Floods Directive specifications) on flood risk at a regional level which can in turn be more readily applied to assess flood economic impacts. Furthermore, in the assumption of an appropriate
A hierarchical statistical model for estimating population properties of quantitative genes
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Wu Rongling
2002-06-01
Full Text Available Abstract Background Earlier methods for detecting major genes responsible for a quantitative trait rely critically upon a well-structured pedigree in which the segregation pattern of genes exactly follow Mendelian inheritance laws. However, for many outcrossing species, such pedigrees are not available and genes also display population properties. Results In this paper, a hierarchical statistical model is proposed to monitor the existence of a major gene based on its segregation and transmission across two successive generations. The model is implemented with an EM algorithm to provide maximum likelihood estimates for genetic parameters of the major locus. This new method is successfully applied to identify an additive gene having a large effect on stem height growth of aspen trees. The estimates of population genetic parameters for this major gene can be generalized to the original breeding population from which the parents were sampled. A simulation study is presented to evaluate finite sample properties of the model. Conclusions A hierarchical model was derived for detecting major genes affecting a quantitative trait based on progeny tests of outcrossing species. The new model takes into account the population genetic properties of genes and is expected to enhance the accuracy, precision and power of gene detection.
Soy protein isolate molecular level contributions to bulk adhesive properties
Shera, Jeanne Norton
Increasing environmental awareness and the recognized health hazards of formaldehyde-based resins has prompted a strong demand for environmentally-responsible adhesives for wood composites. Soy protein-based adhesives have been shown to be commercially viable with 90-day shelf stability and composite physical properties comparable to those of commercial formaldehyde-based particleboards. The main research focus is to isolate and characterize the molecular level features in soy protein isolate responsible for providing mechanical properties, storage stability, and water resistance during adhesive formulation, processing, and wood composite fabrication. Commercial composite board will be reviewed to enhance our understanding of the individual components and processes required for particleboard production. The levels of protein structure will be defined and an overview of current bio-based technology will be presented. In the process, the logic for utilizing soy protein as a sole binder in the adhesive will be reinforced. Variables such as adhesive components, pH, divalent ions, blend aging, protein molecular weight, formulation solids content, and soy protein functionalization will relate the bulk properties of soy protein adhesives to the molecular configuration of the soybean protein. This work has demonstrated that when intermolecular beta-sheet interactions and protein long-range order is disrupted, viscosity and mechanical properties decrease. Storage stability can be maintained through the stabilization of intermolecular beta-sheet interactions. When molecular weight is reduced through enzymatic digestion, long-range order is disrupted and viscosity and mechanical properties decrease accordingly. Processibility and physical properties must be balanced to increase solids while maintaining low viscosity, desirable mechanical properties, and adequate storage stability. The structure of the soybean protein must be related to the particleboard bulk mechanical
Groen, Iris I A; Ghebreab, Sennay; Prins, Hielke; Lamme, Victor A F; Scholte, H Steven
2013-11-27
The visual system processes natural scenes in a split second. Part of this process is the extraction of "gist," a global first impression. It is unclear, however, how the human visual system computes this information. Here, we show that, when human observers categorize global information in real-world scenes, the brain exhibits strong sensitivity to low-level summary statistics. Subjects rated a specific instance of a global scene property, naturalness, for a large set of natural scenes while EEG was recorded. For each individual scene, we derived two physiologically plausible summary statistics by spatially pooling local contrast filter outputs: contrast energy (CE), indexing contrast strength, and spatial coherence (SC), indexing scene fragmentation. We show that behavioral performance is directly related to these statistics, with naturalness rating being influenced in particular by SC. At the neural level, both statistics parametrically modulated single-trial event-related potential amplitudes during an early, transient window (100-150 ms), but SC continued to influence activity levels later in time (up to 250 ms). In addition, the magnitude of neural activity that discriminated between man-made versus natural ratings of individual trials was related to SC, but not CE. These results suggest that global scene information may be computed by spatial pooling of responses from early visual areas (e.g., LGN or V1). The increased sensitivity over time to SC in particular, which reflects scene fragmentation, suggests that this statistic is actively exploited to estimate scene naturalness.
Statistical properties of online avatar numbers in a massive multiplayer online role-playing game
Jiang, Zhi-Qiang; Ren, Fei; Gu, Gao-Feng; Tan, Qun-Zhao; Zhou, Wei-Xing
2010-02-01
Massive multiplayer online role-playing games (MMORPGs) have been very popular in the past few years. The profit of an MMORPG company is proportional to how many users registered, and the instant number of online avatars is a key factor to assess how popular an MMORPG is. We use the online-offline logs on an MMORPG server to reconstruct the instant number of online avatars per second and investigate its statistical properties. We find that the online avatar number exhibits one-day periodic behavior and clear intraday pattern, the fluctuation distribution of the online avatar numbers has a leptokurtic non-Gaussian shape with power-law tails, and the increments of online avatar numbers after removing the intraday pattern are uncorrelated and the associated absolute values have long-term correlation. In addition, both time series exhibit multifractal nature.
Statistical Properties and Multifractal Behaviors of Market Returns by Ising Dynamic Systems
Fang, Wen; Wang, Jun
An interacting-agent model of speculative activity explaining price formation in financial markets is considered in the present paper, which based on the stochastic Ising model and the mean field theory. The model describes the interaction strength among the agents as well as an external field, and the corresponding random logarithmic price return process is investigated. According to the empirical research of the model, the time series formed by this Ising model exhibits the bursting typical of volatility clustering, the fat-tail phenomenon, the power-law distribution tails and the long-time memory. The statistical properties of the returns of Hushen 300 Index, Shanghai Stock Exchange (SSE) Composite Index and Shenzhen Stock Exchange (SZSE) Component Index are also studied for comparison between the real time series and the simulated ones. Further, the multifractal detrended fluctuation analysis is applied to investigate the time series returns simulated by Ising model have the distribution multifractality as well as the correlation multifractality.
Statistical properties of damped Lyman-alpha systems from Sloan Digital Sky Survey DR12
Bird, Simeon; Ho, Shirley
2016-01-01
We present new estimates for the statistical properties of damped Lyman-$\\alpha$ absorbers (DLAs). We compute the column density distribution function at $z>2$, the line density, $\\mathrm{d}N/\\mathrm{d}X$, and the neutral hydrogen density, $\\Omega_\\mathrm{DLA}$. Our estimates are derived from the DLA catalogue of \\cite{Garnett:2016}, which uses the SDSS--III DR12 quasar spectroscopic survey. This catalogue provides a probability that a given spectrum contains a DLA, allowing us to use even the noisiest data without biasing our results and thus substantially increase our sample size. We measure a non-zero column density distribution function at $95\\%$ confidence for all column densities $N_\\mathrm{HI} 4$. We show that our results are insensitive to the signal-to-noise ratio of the spectra, but that there is a residual dependence on quasar redshift for $z<2.5$, which may be due to remaining systematics in our analysis.
Statistical properties of daily ensemble variables in the Chinese stock markets
Gu, Gao-Feng; Zhou, Wei-Xing
2007-09-01
We study dynamical behavior of the Chinese stock markets by investigating the statistical properties of daily ensemble return and variety defined, respectively, as the mean and the standard deviation of the ensemble daily price return of a portfolio of stocks traded in China's stock markets on a given day. The distribution of the daily ensemble return has an exponential form in the center and power-law tails, while the variety distribution is lognormal in the bulk followed by a power-law tail for large variety. Based on detrended fluctuation analysis, R/S analysis and modified R/S analysis, we find evidence of long memory in the ensemble return and strong evidence of long memory in the evolution of variety.
Statistical properties of daily ensemble variables in the Chinese stock markets
Gu, G F; Gu, Gao-Feng; Zhou, Wei-Xing
2006-01-01
We study dynamical behavior of the Chinese stock markets by investigating the statistical properties of daily ensemble returns and varieties defined respectively as the mean and the standard deviation of the ensemble daily price returns of a portfolio of stocks traded in China's stock markets on a given day. The distribution of the daily ensemble returns has an exponential form in the center and power-law tails, while the variety distribution is log-Gaussian in the bulk followed by a power-law tail for large varieties. Based on detrended fluctuation analysis, R/S analysis and modified R/S analysis, we find evidence of long memory in the ensemble returns and strong evidence of long memory in the evolution of variety.
Statistical Properties of Thermal Noise Driving the Brownian Particles in Fluids
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Tóthová Jana
2016-01-01
Full Text Available In several recent works high-resolution interferometric detection allowed to study the Brownian motion of optically trapped microparticles in air and fluids. The observed positional fluctuations of the particles are well described by the generalized Langevin equation with the Boussinesq-Basset “history force” instead of the Stokes friction, which is valid only for the steady motion. Recently, also the time correlation function of the thermal random force Fth driving the Brownian particles through collisions with the surrounding molecules has been measured. In the present contribution we propose a method to describe the statistical properties of Fth in incompressible fluids. Our calculations show that the time decay of the correlator 〈Fth(tFth(0〉 is significantly slower than that found in the literature. It is also shown how the “color” of the thermal noise can be determined from the measured positions of the Brownian particles.
Statistical properties of a discrete version of the Ornstein-Uhlenbeck process.
Larralde, Hernán
2004-02-01
A discrete version of the Ornstein-Uhlenbeck process is discussed which arises from a simple generalization of the master equation of the random walk. The calculation of the statistical properties of the free propagator for this process can be obtained using essentially the same formalism as for simple random walks. These calculations are carried out in some detail for the one-dimensional case. The usual equation for the evolution of the probability distribution of the Ornstein-Uhlenbeck process is recovered in the continuum limit if the jump distribution has a finite variance. However, the discrete process is also well defined for long tailed jump distributions and, thus, can be used to describe a Lèvy walk under the effect of a harmonic potential. Finally, a brief discussion of the generalization of this process to describe random walks in general potentials is presented and briefly compared with results arising from the fractional diffusion approach.
Probing the statistical properties of CMB $B$-mode polarization through Minkowski Functionals
Zhao, W
2015-01-01
The detection of the magnetic type $B$-mode polarization is the main goal of future cosmic microwave background (CMB) experiments. In the standard model, the $B$-mode map is a strongly non-gaussian field due to the lensed component. Besides the two-point correlation function, the other statistics are also very important to dig the information of the polarization map. In this paper, we employ the Minkowski functionals to study the morphological properties of the lensed $B$-mode maps. We find that the deviations from Gaussianity are very significant for both full and partial-sky surveys. As an application of the analysis, we investigate the morphological imprints of the foreground residuals in the $B$-mode map. We find that even for very tiny foreground residuals, the effects on the map can be detected by the Minkowski functional analysis. Therefore, it provides a complementary way to investigate the foreground contaminations in the CMB studies.
Probing the statistical properties of CMB B-mode polarization through Minkowski functionals
Santos, Larissa; Wang, Kai; Zhao, Wen
2016-07-01
The detection of the magnetic type B-mode polarization is the main goal of future cosmic microwave background (CMB) experiments. In the standard model, the B-mode map is a strong non-gaussian field due to the CMB lensing component. Besides the two-point correlation function, the other statistics are also very important to dig the information of the polarization map. In this paper, we employ the Minkowski functionals to study the morphological properties of the lensed B-mode maps. We find that the deviations from Gaussianity are very significant for both full and partial-sky surveys. As an application of the analysis, we investigate the morphological imprints of the foreground residuals in the B-mode map. We find that even for very tiny foreground residuals, the effects on the map can be detected by the Minkowski functional analysis. Therefore, it provides a complementary way to investigate the foreground contaminations in the CMB studies.
On the statistical properties of viral misinformation in online social media
Bessi, Alessandro
2016-01-01
The massive diffusion of online social media allows for the rapid and uncontrolled spreading of conspiracy theories, hoaxes, unsubstantiated claims, and false news. Such an impressive amount of misinformation can influence policy preferences and encourage behaviors strongly divergent from recommended practices. In this paper, we study the statistical properties of viral misinformation in online social media. By means of methods belonging to Extreme Value Theory, we show that the number of extremely viral posts over time follows a homogeneous Poisson process, and that the interarrival times between such posts are independent and identically distributed, following an exponential distribution. Moreover, we characterize the uncertainty around the rate parameter of the Poisson process through Bayesian methods. Finally, we are able to derive the predictive posterior probability distribution of the number of posts exceeding a certain threshold of shares over a finite interval of time.
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J. A. Reshi
2014-12-01
Full Text Available In this paper, a new class of Size-biased Generalized Gamma (SBGG distribution is defined. A Size-biased Generalized Gamma (SBGG distribution, a particular case of weighted Generalized Gamma distribution, taking the weights as the variate values has been defined. The important statistical properties including hazard functions, reverse hazard functions, mode, moment generating function, characteristic function, Shannon’s entropy, generalized entropy and Fisher’s information matrix of the new model have been derived and studied. Here, we also study SBGG entropy estimation, Akaike and Bayesian information criterion. A likelihood ratio test for size-biasedness is conducted. The estimation of parameters is obtained by employing the classical methods of estimation especially method of moments and maximum likelihood estimator.
On the statistical properties of viral misinformation in online social media
Bessi, Alessandro
2017-03-01
The massive diffusion of online social media allows for the rapid and uncontrolled spreading of conspiracy theories, hoaxes, unsubstantiated claims, and false news. Such an impressive amount of misinformation can influence policy preferences and encourage behaviors strongly divergent from recommended practices. In this paper, we study the statistical properties of viral misinformation in online social media. By means of methods belonging to Extreme Value Theory, we show that the number of extremely viral posts over time follows a homogeneous Poisson process, and that the interarrival times between such posts are independent and identically distributed, following an exponential distribution. Moreover, we characterize the uncertainty around the rate parameter of the Poisson process through Bayesian methods. Finally, we are able to derive the predictive posterior probability distribution of the number of posts exceeding a certain threshold of shares over a finite interval of time.
Signal induced Symmetry Breaking in Noise Statistical Properties of Data Analysis
Perotti, Luca; Bessis, Daniel
2010-01-01
From a time series whose data are embedded in heavy noise, we construct an Hilbert space operator (J-operator) whose discrete spectrum represents the signal while the essential spectrum located on the unit circle, is associated with the noise. Furthermore the essential spectrum, in the absence of signal, is built from roots of unity ("clock" distribution). These results are independent of the statistical properties of the noise that can be Gaussian, non-Gaussian, pink or even without second moment (Levy). The presence of the signal has for effect to break the clock angular distribution of the essential spectrum on the unit circle. A discontinuity, proportional to the intensity of the signal, appears in the angular distribution. The sensitivity of this method is definitely better than standard techniques. We build an example that supports our claims.
Han, S. M.; Hahm, I.
2015-12-01
We evaluated the background noise level of seismic stations in order to collect the observation data of high quality and produce accurate seismic information. Determining of the background noise level was used PSD (Power Spectral Density) method by McNamara and Buland (2004) in this study. This method that used long-term data is influenced by not only innate electronic noise of sensor and a pulse wave resulting from stabilizing but also missing data and controlled by the specified frequency which is affected by the irregular signals without site characteristics. It is hard and inefficient to implement process that filters out the abnormal signal within the automated system. To solve these problems, we devised a method for extracting the data which normally distributed with 90 to 99% confidence intervals at each period. The availability of the method was verified using 62-seismic stations with broadband and short-period sensors operated by the KMA (Korea Meteorological Administration). Evaluation standards were NHNM (New High Noise Model) and NLNM (New Low Noise Model) published by the USGS (United States Geological Survey). It was designed based on the western United States. However, Korean Peninsula surrounded by the ocean on three sides has a complicated geological structure and a high population density. So, we re-designed an appropriate model in Korean peninsula by statistically combined result. The important feature is that secondary-microseism peak appeared at a higher frequency band. Acknowledgements: This research was carried out as a part of "Research for the Meteorological and Earthquake Observation Technology and Its Application" supported by the 2015 National Institute of Meteorological Research (NIMR) in the Korea Meteorological Administration.
Statistical Properties of Solar Active Regions Based on Objective Detection and Characterization
Zhang, Jie
2010-05-01
We present a study of the statistical properties of solar magnetic regions based on objective detection and characterization. The uniformity and consistency of the magnetogram images provided by SOHO/MDI make it an ideal database for automated detection of solar magnetic features. The results of detection are mainly controlled by the following four parameters or thresholds: (1) magnetic intensity threshold of kernel pixels (to find strong field regions), (2) erosion size threshold for morphological opening operation (to remove small patches), (3) magnetic intensity threshold of AR pixels (to recover the whole size of an AR), (4) dilation size threshold for morphological closing operation (to merge neighboring patches to form a whole AR). We find that the best combination of the above four parameters is (1) 250 Gauss, (2) 10 Mm, (3) 50 Gauss, and (4) 10 Mm, which yields a detection of 1772 ARs that is most similar to the NOAA catalog based on human operators; as a comparison, NOAA/SWPC reports 2281 ARs during the same period. By varying the values of the control parameters, the number of ARs detected can range from as small as 1000 to as large as 10000. With these data, we are now able to make detailed statistical study of solar active regions, including (1) how AR number and emerged magnetic flux vary with solar cycle? (2) how AR number and emerged magnetic flux vary with latitude during different phases of solar cycle? (3) the distribution of AR number with respect to the size; Is the distribution power-law, Gaussian or log-normal, and the implication on the mechanisms of generating ARs? Is there a north-south asymmetry of ARs? How the strong magnetic patches distribute within an AR? This study provides us new insights on the properties and generations of solar active regions.
Bellan, Diego; Pignari, Sergio A.
2016-07-01
This work deals with the statistical characterization of real-time digital measurement of the amplitude of harmonics affected by frequency instability. In fact, in modern power systems both the presence of harmonics and frequency instability are well-known and widespread phenomena mainly due to nonlinear loads and distributed generation, respectively. As a result, real-time monitoring of voltage/current frequency spectra is of paramount importance as far as power quality issues are addressed. Within this framework, a key point is that in many cases real-time continuous monitoring prevents the application of sophisticated algorithms to extract all the information from the digitized waveforms because of the required computational burden. In those cases only simple evaluations such as peak search of discrete Fourier transform are implemented. It is well known, however, that a slight change in waveform frequency results in lack of sampling synchronism and uncertainty in amplitude estimate. Of course the impact of this phenomenon increases with the order of the harmonic to be measured. In this paper an approximate analytical approach is proposed in order to describe the statistical properties of the measured magnitude of harmonics affected by frequency instability. By providing a simplified description of the frequency behavior of the windows used against spectral leakage, analytical expressions for mean value, variance, cumulative distribution function, and probability density function of the measured harmonics magnitude are derived in closed form as functions of waveform frequency treated as a random variable.
Statistical properties of P-SV mode converted ultrasonic speckles reflected from an interface
Institute of Scientific and Technical Information of China (English)
ZHU Hongmao; ZHENG Weihua; CHEN Fulong
2004-01-01
The statistical properties of the mode converted SV wave speckles in the back scattering space were studied as ultrasonic P waves were incident on a strongly scattering interface. Based on the Frensel-Huygens theory and the correlation principle, the Rayleigh distribution of the SV wave speckle amplitude and the formula for calculating the average lateral size of the SV wave speckles were obtained. Besides, the probability density function of the normalized intensity of the SV wave speckles received by a transverse wave probe with an aperture of some size was deduced. The probability density function was related to the average number of the speckles received by the probe. Two transverse wave probes with apertures in different size were employed to measure the sound intensity of the SV wave speckles in the experiment. After the experimental data of the speckle intensity were analyzed statistically,it was shown that the experimental results were in good agreement with the theoretical ones.Thus, the presented theoretical conclusions were proved to be correct.
Open system of interacting fermions: statistical properties of cross sections and fluctuations.
Celardo, G L; Izrailev, F M; Zelevinsky, V G; Berman, G P
2007-09-01
Statistical properties of cross sections are studied for an open system of interacting fermions. The description is based on the effective non-Hermitian Hamiltonian that accounts for the existence of open decay channels preserving the unitarity of the scattering matrix. The intrinsic interaction is modeled by the two-body random ensemble of variable strength. In particular, the crossover region from isolated to overlapping resonances accompanied by the effect of the width redistribution creating superradiant and trapped states is studied in detail. The important observables, such as average cross section, its fluctuations, autocorrelation functions of the cross section, and scattering matrix, are very sensitive to the coupling of the intrinsic states to the continuum around the crossover. A detailed comparison is made of our results with standard predictions of statistical theory of cross sections, such as the Hauser-Feshbach formula for the average cross section and Ericson theory of fluctuations and correlations of cross sections. Strong deviations are found in the crossover region, along with the dependence on intrinsic interactions and the degree of chaos inside the system.
Statistical Properties of Lorenz-like Flows, Recent Developments and Perspectives
Araujo, Vitor; Galatolo, Stefano; Pacifico, Maria José
We comment on the mathematical results about the statistical behavior of Lorenz equations and its attractor, and more generally on the class of singular hyperbolic systems. The mathematical theory of such kind of systems turned out to be surprisingly difficult. It is remarkable that a rigorous proof of the existence of the Lorenz attractor was presented only around the year 2000 with a computer-assisted proof together with an extension of the hyperbolic theory developed to encompass attractors robustly containing equilibria. We present some of the main results on the statistical behavior of such systems. We show that for attractors of three-dimensional flows, robust chaotic behavior is equivalent to the existence of certain hyperbolic structures, known as singular-hyperbolicity. These structures, in turn, are associated with the existence of physical measures: in low dimensions, robust chaotic behavior for flows ensures the existence of a physical measure. We then give more details on recent results on the dynamics of singular-hyperbolic (Lorenz-like) attractors: (1) there exists an invariant foliation whose leaves are forward contracted by the flow (and further properties which are useful to understand the statistical properties of the dynamics); (2) there exists a positive Lyapunov exponent at every orbit; (3) there is a unique physical measure whose support is the whole attractor and which is the equilibrium state with respect to the center-unstable Jacobian; (4) this measure is exact dimensional; (5) the induced measure on a suitable family of cross-sections has exponential decay of correlations for Lipschitz observables with respect to a suitable Poincaré return time map; (6) the hitting time associated to Lorenz-like attractors satisfy a logarithm law; (7) the geometric Lorenz flow satisfies the Almost Sure Invariance Principle (ASIP) and the Central Limit Theorem (CLT); (8) the rate of decay of large deviations for the volume measure on the ergodic basin of
Pradhan, Prabhakar
2015-01-01
Light wave reflection from optical disordered media is always associate with its phase, and the phase statistics influence the reflection statistics. We report a detailed numerical study of the statistics of the reflection coefficient RR* and its associated phase(theta) for plane electromagnetic waves reflected from one dimensional (1D) Gaussian white-noise optical disordered media, ranging from weak to strong disordered regimes. We solve numerically the full Fokker-Planck (FP) equation for the joint probability distribution in the RR* - phase(theta) space for different lengths of the sample with different disorder strengths. The statistical optical transport properties of 1D optical disordered media are calculated using the full FP equation numerically. This constitutes a complete solution for the reflection phase statistics and its effects on light transport properties in a 1D Gaussian white-noise disordered optical potentials. Our results show the regime of the validation of the random phase approximations...
Directory of Open Access Journals (Sweden)
Daniela ŞTEFĂNESCU
2011-08-01
Full Text Available The issues referring to official statistics quality and reliability became the main topics of debates as far as statistical governance in Europe is concerned. The Council welcomed the Commission Communication to the European Parliament and to the Council « Towards robust quality management for European Statistics » (COM 211, appreciating that the approach and the objective of the strategy would confer the European Statistical System (ESS the quality management framework for the coordination of consolidated economic policies. The Council pointed out that the European Statistical System management was improved during recent years, that progress was noticed in relation with high quality statistics production and dissemination within the European Union, but has also noticed that, in the context of recent financial crisis, certain weaknesses were identified, particularly related to quality management general framework.„Greece Case” proved that progresses were not enough for guaranteeing the complete independence of national statistical institutes and entailed the need for further consolidating ESS governance. Several undertakings are now in the preparatory stage, in accordance with the Commission Communication; these actions are welcomed, but the question arise: are these sufficient for definitively solving the problem?The paper aims to go ahead in the attempt of identifying a different way, innovative (courageous! on the long run, towards an advanced institutional structure of ESS, by setting up the European System of Statistical Institutes, similar to the European System of Central Banks, that would require a change in the Treaty.
Statistical properties of pairwise distances between leaves on a random Yule tree.
Sheinman, Michael; Massip, Florian; Arndt, Peter F
2015-01-01
A Yule tree is the result of a branching process with constant birth and death rates. Such a process serves as an instructive null model of many empirical systems, for instance, the evolution of species leading to a phylogenetic tree. However, often in phylogeny the only available information is the pairwise distances between a small fraction of extant species representing the leaves of the tree. In this article we study statistical properties of the pairwise distances in a Yule tree. Using a method based on a recursion, we derive an exact, analytic and compact formula for the expected number of pairs separated by a certain time distance. This number turns out to follow a increasing exponential function. This property of a Yule tree can serve as a simple test for empirical data to be well described by a Yule process. We further use this recursive method to calculate the expected number of the n-most closely related pairs of leaves and the number of cherries separated by a certain time distance. To make our results more useful for realistic scenarios, we explicitly take into account that the leaves of a tree may be incompletely sampled and derive a criterion for poorly sampled phylogenies. We show that our result can account for empirical data, using two families of birds species.
Statistical properties of pairwise distances between leaves on a random Yule tree.
Directory of Open Access Journals (Sweden)
Michael Sheinman
Full Text Available A Yule tree is the result of a branching process with constant birth and death rates. Such a process serves as an instructive null model of many empirical systems, for instance, the evolution of species leading to a phylogenetic tree. However, often in phylogeny the only available information is the pairwise distances between a small fraction of extant species representing the leaves of the tree. In this article we study statistical properties of the pairwise distances in a Yule tree. Using a method based on a recursion, we derive an exact, analytic and compact formula for the expected number of pairs separated by a certain time distance. This number turns out to follow a increasing exponential function. This property of a Yule tree can serve as a simple test for empirical data to be well described by a Yule process. We further use this recursive method to calculate the expected number of the n-most closely related pairs of leaves and the number of cherries separated by a certain time distance. To make our results more useful for realistic scenarios, we explicitly take into account that the leaves of a tree may be incompletely sampled and derive a criterion for poorly sampled phylogenies. We show that our result can account for empirical data, using two families of birds species.
Statistical properties of cross-correlation in the Korean stock market
Oh, G.; Eom, C.; Wang, F.; Jung, W.-S.; Stanley, H. E.; Kim, S.
2011-01-01
We investigate the statistical properties of the cross-correlation matrix between individual stocks traded in the Korean stock market using the random matrix theory (RMT) and observe how these affect the portfolio weights in the Markowitz portfolio theory. We find that the distribution of the cross-correlation matrix is positively skewed and changes over time. We find that the eigenvalue distribution of original cross-correlation matrix deviates from the eigenvalues predicted by the RMT, and the largest eigenvalue is 52 times larger than the maximum value among the eigenvalues predicted by the RMT. The β_{473} coefficient, which reflect the largest eigenvalue property, is 0.8, while one of the eigenvalues in the RMT is approximately zero. Notably, we show that the entropy function E(σ) with the portfolio risk σ for the original and filtered cross-correlation matrices are consistent with a power-law function, E( σ) σ^{-γ}, with the exponent γ 2.92 and those for Asian currency crisis decreases significantly.
McCauley, Patrick I; Schanche, Nicole; Evans, Kaitlin E; Su, Chuan; McKillop, Sean; Reeves, Katharine K
2015-01-01
We present a statistical study of prominence and filament eruptions observed by the Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics Observatory (SDO). Several properties are recorded for 904 events that were culled from the Heliophysics Event Knowledgebase (HEK) and incorporated into an online catalog for general use. These characteristics include the filament and eruption type, eruption symmetry and direction, apparent twisting and writhing motions, and the presence of vertical threads and coronal cavities. Associated flares and white-light coronal mass ejections (CME) are also recorded. Total rates are given for each property along with how they differ among filament types. We also examine the kinematics of 106 limb events to characterize the distinct slow- and fast-rise phases often exhibited by filament eruptions. The average fast-rise onset height, slow-rise duration, slow-rise velocity, maximum field-of-view (FOV) velocity, and maximum FOV acceleration are 83 Mm, 4.4 hours, 2.1 km/s, 106 km...
Geostatistical and Statistical Classification of Sea-Ice Properties and Provinces from SAR Data
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Ute C. Herzfeld
2016-07-01
Full Text Available Recent drastic reductions in the Arctic sea-ice cover have raised an interest in understanding the role of sea ice in the global system as well as pointed out a need to understand the physical processes that lead to such changes. Satellite remote-sensing data provide important information about remote ice areas, and Synthetic Aperture Radar (SAR data have the advantages of penetration of the omnipresent cloud cover and of high spatial resolution. A challenge addressed in this paper is how to extract information on sea-ice types and sea-ice processes from SAR data. We introduce, validate and apply geostatistical and statistical approaches to automated classification of sea ice from SAR data, to be used as individual tools for mapping sea-ice properties and provinces or in combination. A key concept of the geostatistical classification method is the analysis of spatial surface structures and their anisotropies, more generally, of spatial surface roughness, at variable, intermediate-sized scales. The geostatistical approach utilizes vario parameters extracted from directional vario functions, the parameters can be mapped or combined into feature vectors for classification. The method is flexible with respect to window sizes and parameter types and detects anisotropies. In two applications to RADARSAT and ERS-2 SAR data from the area near Point Barrow, Alaska, it is demonstrated that vario-parameter maps may be utilized to distinguish regions of different sea-ice characteristics in the Beaufort Sea, the Chukchi Sea and in Elson Lagoon. In a third and a fourth case study the analysis is taken further by utilizing multi-parameter feature vectors as inputs for unsupervised and supervised statistical classification. Field measurements and high-resolution aerial observations serve as basis for validation of the geostatistical-statistical classification methods. A combination of supervised classification and vario-parameter mapping yields best results
Danehkar, Ashkbiz
2016-11-01
The proEQUIB library calculates atomic level populations and line emissivities in statistical equilibrium in multi-level atoms for different physical conditions of stratified layers in a nebula where chemical elements are ionized. It includes an Interactive Data Language (IDL)/GNU Data Language (GDL) implementation of the Fortran code EQUIB (ascl:1603.005).
Energy Technology Data Exchange (ETDEWEB)
Mohammadi, M [Department of Physics, Science and Research Campus Azad University of Tehran, Tehran (Iran, Islamic Republic of); Naderi, M H [Quantum Optics Group, Department of Physics, University of Isfahan, Isfahan (Iran, Islamic Republic of); Soltanolkotabi, M [Quantum Optics Group, Department of Physics, University of Isfahan, Isfahan (Iran, Islamic Republic of)
2007-02-09
The temporal evolution of quantum statistical properties of an interacting atom-radiation field system in the presence of a classical homogeneous gravitational field is investigated within the framework of the Jaynes-Cummings model. To analyse the dynamical evolution of the atom-radiation system a quantum treatment of the internal and external dynamics of the atom is presented based on an alternative su(2) dynamical algebraic structure. By solving the Schroedinger equation in the interaction picture, the evolving state of the system is found by which the influence of the gravitational field on the dynamical behaviour of the atom-radiation system is explored. Assuming that initially the radiation field is prepared in a coherent state and the two-level atom is in a coherent superposition of the excited and ground states, the influence of gravity on the collapses and revivals of the atomic population inversion, atomic dipole squeezing, atomic momentum diffusion, photon counting statistics and quadrature squeezing of the radiation field is studied.
Statistical mechanics of pluripotency.
MacArthur, Ben D; Lemischka, Ihor R
2013-08-01
Recent reports using single-cell profiling have indicated a remarkably dynamic view of pluripotent stem cell identity. Here, we argue that the pluripotent state is not well defined at the single-cell level but rather is a statistical property of stem cell populations, amenable to analysis using the tools of statistical mechanics and information theory.
Davis, J.C.
2000-01-01
Geologists may feel that geological data are not amenable to statistical analysis, or at best require specialized approaches such as nonparametric statistics and geostatistics. However, there are many circumstances, particularly in systematic studies conducted for environmental or regulatory purposes, where traditional parametric statistical procedures can be beneficial. An example is the application of analysis of variance to data collected in an annual program of measuring groundwater levels in Kansas. Influences such as well conditions, operator effects, and use of the water can be assessed and wells that yield less reliable measurements can be identified. Such statistical studies have resulted in yearly improvements in the quality and reliability of the collected hydrologic data. Similar benefits may be achieved in other geological studies by the appropriate use of classical statistical tools.
Abbout, Adel
2016-08-05
Using the tools of random matrix theory we develop a statistical analysis of the transport properties of thermoelectric low-dimensional systems made of two electron reservoirs set at different temperatures and chemical potentials, and connected through a low-density-of-states two-level quantum dot that acts as a conducting chaotic cavity. Our exact treatment of the chaotic behavior in such devices lies on the scattering matrix formalism and yields analytical expressions for the joint probability distribution functions of the Seebeck coefficient and the transmission profile, as well as the marginal distributions, at arbitrary Fermi energy. The scattering matrices belong to circular ensembles which we sample to numerically compute the transmission function, the Seebeck coefficient, and their relationship. The exact transport coefficients probability distributions are found to be highly non-Gaussian for small numbers of conduction modes, and the analytical and numerical results are in excellent agreement. The system performance is also studied, and we find that the optimum performance is obtained for half-transparent quantum dots; further, this optimum may be enhanced for systems with few conduction modes.
Abbout, Adel; Ouerdane, Henni; Goupil, Christophe
2016-09-01
Using the tools of random matrix theory we develop a statistical analysis of the transport properties of thermoelectric low-dimensional systems made of two electron reservoirs set at different temperatures and chemical potentials, and connected through a low-density-of-states two-level quantum dot that acts as a conducting chaotic cavity. Our exact treatment of the chaotic behavior in such devices lies on the scattering matrix formalism and yields analytical expressions for the joint probability distribution functions of the Seebeck coefficient and the transmission profile, as well as the marginal distributions, at arbitrary Fermi energy. The scattering matrices belong to circular ensembles which we sample to numerically compute the transmission function, the Seebeck coefficient, and their relationship. The exact transport coefficients probability distributions are found to be highly non-Gaussian for small numbers of conduction modes, and the analytical and numerical results are in excellent agreement. The system performance is also studied, and we find that the optimum performance is obtained for half-transparent quantum dots; further, this optimum may be enhanced for systems with few conduction modes.
Review of high-level waste form properties. [146 bibliographies
Energy Technology Data Exchange (ETDEWEB)
Rusin, J.M.
1980-12-01
This report is a review of waste form options for the immobilization of high-level-liquid wastes from the nuclear fuel cycle. This review covers the status of international research and development on waste forms as of May 1979. Although the emphasis in this report is on waste form properties, process parameters are discussed where they may affect final waste form properties. A summary table is provided listing properties of various nuclear waste form options. It is concluded that proposed waste forms have properties falling within a relatively narrow range. In regard to crystalline versus glass waste forms, the conclusion is that either glass of crystalline materials can be shown to have some advantage when a single property is considered; however, at this date no single waste form offers optimum properties over the entire range of characteristics investigated. A long-term effort has been applied to the development of glass and calcine waste forms. Several additional waste forms have enough promise to warrant continued research and development to bring their state of development up to that of glass and calcine. Synthetic minerals, the multibarrier approach with coated particles in a metal matrix, and high pressure-high temperature ceramics offer potential advantages and need further study. Although this report discusses waste form properties, the total waste management system should be considered in the final selection of a waste form option. Canister design, canister materials, overpacks, engineered barriers, and repository characteristics, as well as the waste form, affect the overall performance of a waste management system. These parameters were not considered in this comparison.
1998-01-01
We systematically study the exclusion statistics for quasi-particles for Conformal Field Theory spectra by employing a method based on recursion relations for truncated spectra. Our examples include generalized fermions in c
1983-12-01
34 ; "" ***’, ." . ’-*,’ .’ . . -. ." " . .." . . ~ .. * . . -" - -’-’- "-’-’ - . 4- NO. OF CUPIES Dr. Morris DeGroot I Statistics Department Carnegie-Mellon University
The Use of Social Media for Communication In Official Statistics at European Level
Directory of Open Access Journals (Sweden)
Ionela-Roxana GLĂVAN
2016-12-01
Full Text Available Social media tools are wide spread in web communication and are gaining popularity in the communication process between public institutions and citizens. This study conducts an analysis on how social media is used by Official Statistical Institutes to interact with citizens and disseminate information. A linear regression technique is performed to examine which social media platforms (Twitter or Facebook is a more effective tool in the communication process in the official statistics area. Our study suggests that Twitter is a more powerful tool than Facebook in enhancing the relationship between official statistics and citizens, complying with several other studies. Next, we performed an analysis on Twitter network characteristics discussing “official statistics” using NodeXL that revealed the unexploited potential of this network by official statistical agencies.
Statistical research on the motion properties of the magnetotail current sheet:Cluster observations
Institute of Scientific and Technical Information of China (English)
H.REME; E.LUCEK
2010-01-01
The origin of the flapping motion of the earth’s magnetotail current sheet is one of the most important problems in the magnetotail dynamics.Using Cluster data,we make a statistical research on the motion properties of the magnetotail current sheet of 2001 and 2003.We calculate the velocities of the magnetotail current sheet using new methods and obtain the distribution of the magnetotail current sheet velocities in the X-Y plane in GSE coordinate system.Our results show that although most of the current sheets were propagating toward the tail flanks and those of the exceptions lay in dusk side,which is consistent with previous studies,the proportions of the current sheet which were propagating toward midnight (where |YGSE|=0) were higher than those in previous studies.Motions of the current sheet in the middle area (|YGSE|<8 Re) of the magnetotail are investigated.Relatively high value of the Z component of the velocity further confirms that the middle area of the magnetotail might be a source region for the motion of the current sheets which were propagating towards the tail flanks.According to our case studies,the way the current sheets propagated toward midnight area differs significantly from that toward dusk and dawn side,from which we infer that there might be two different kinds of current sheet motions originated from different sources.The statistical results of this paper may give some clues for further studies on the origin of the flapping motion of the magnetotail current sheet.
Statistical properties and pre-hit dynamics of price limit hits in the Chinese stock markets.
Wan, Yu-Lei; Xie, Wen-Jie; Gu, Gao-Feng; Jiang, Zhi-Qiang; Chen, Wei; Xiong, Xiong; Zhang, Wei; Zhou, Wei-Xing
2015-01-01
Price limit trading rules are adopted in some stock markets (especially emerging markets) trying to cool off traders' short-term trading mania on individual stocks and increase market efficiency. Under such a microstructure, stocks may hit their up-limits and down-limits from time to time. However, the behaviors of price limit hits are not well studied partially due to the fact that main stock markets such as the US markets and most European markets do not set price limits. Here, we perform detailed analyses of the high-frequency data of all A-share common stocks traded on the Shanghai Stock Exchange and the Shenzhen Stock Exchange from 2000 to 2011 to investigate the statistical properties of price limit hits and the dynamical evolution of several important financial variables before stock price hits its limits. We compare the properties of up-limit hits and down-limit hits. We also divide the whole period into three bullish periods and three bearish periods to unveil possible differences during bullish and bearish market states. To uncover the impacts of stock capitalization on price limit hits, we partition all stocks into six portfolios according to their capitalizations on different trading days. We find that the price limit trading rule has a cooling-off effect (object to the magnet effect), indicating that the rule takes effect in the Chinese stock markets. We find that price continuation is much more likely to occur than price reversal on the next trading day after a limit-hitting day, especially for down-limit hits, which has potential practical values for market practitioners.
Statistical properties and pre-hit dynamics of price limit hits in the Chinese stock markets.
Directory of Open Access Journals (Sweden)
Yu-Lei Wan
Full Text Available Price limit trading rules are adopted in some stock markets (especially emerging markets trying to cool off traders' short-term trading mania on individual stocks and increase market efficiency. Under such a microstructure, stocks may hit their up-limits and down-limits from time to time. However, the behaviors of price limit hits are not well studied partially due to the fact that main stock markets such as the US markets and most European markets do not set price limits. Here, we perform detailed analyses of the high-frequency data of all A-share common stocks traded on the Shanghai Stock Exchange and the Shenzhen Stock Exchange from 2000 to 2011 to investigate the statistical properties of price limit hits and the dynamical evolution of several important financial variables before stock price hits its limits. We compare the properties of up-limit hits and down-limit hits. We also divide the whole period into three bullish periods and three bearish periods to unveil possible differences during bullish and bearish market states. To uncover the impacts of stock capitalization on price limit hits, we partition all stocks into six portfolios according to their capitalizations on different trading days. We find that the price limit trading rule has a cooling-off effect (object to the magnet effect, indicating that the rule takes effect in the Chinese stock markets. We find that price continuation is much more likely to occur than price reversal on the next trading day after a limit-hitting day, especially for down-limit hits, which has potential practical values for market practitioners.
Statistical Properties and Pre-Hit Dynamics of Price Limit Hits in the Chinese Stock Markets
Wan, Yu-Lei; Xie, Wen-Jie; Gu, Gao-Feng; Jiang, Zhi-Qiang; Chen, Wei; Xiong, Xiong; Zhang, Wei; Zhou, Wei-Xing
2015-01-01
Price limit trading rules are adopted in some stock markets (especially emerging markets) trying to cool off traders’ short-term trading mania on individual stocks and increase market efficiency. Under such a microstructure, stocks may hit their up-limits and down-limits from time to time. However, the behaviors of price limit hits are not well studied partially due to the fact that main stock markets such as the US markets and most European markets do not set price limits. Here, we perform detailed analyses of the high-frequency data of all A-share common stocks traded on the Shanghai Stock Exchange and the Shenzhen Stock Exchange from 2000 to 2011 to investigate the statistical properties of price limit hits and the dynamical evolution of several important financial variables before stock price hits its limits. We compare the properties of up-limit hits and down-limit hits. We also divide the whole period into three bullish periods and three bearish periods to unveil possible differences during bullish and bearish market states. To uncover the impacts of stock capitalization on price limit hits, we partition all stocks into six portfolios according to their capitalizations on different trading days. We find that the price limit trading rule has a cooling-off effect (object to the magnet effect), indicating that the rule takes effect in the Chinese stock markets. We find that price continuation is much more likely to occur than price reversal on the next trading day after a limit-hitting day, especially for down-limit hits, which has potential practical values for market practitioners. PMID:25874716
Directory of Open Access Journals (Sweden)
Christoph eRedies
2013-11-01
Full Text Available Frames provide a visual link between artworks and their surround. We asked how image properties change as an observer zooms out from viewing a painting alone, to viewing the painting with its frame and, finally, the framed painting in its museum environment (museum scene. To address this question, we determined three higher-order image properties that are based on histograms of oriented luminance gradients. First, complexity was measured as the sum of the strengths of all gradients in the image. Second, we determined the self-similarity of histograms of the orientated gradients at different levels of spatial analysis. Third, we analyzed how much gradient strength varied across orientations (anisotropy. Results were obtained for three art museums that exhibited paintings from three major periods of Western art. In all three museums, the mean complexity of the frames was higher than that of the paintings or the museum scenes. Frames thus provide a barrier of complexity between the paintings and their exterior. By contrast, self-similarity and anisotropy values of images of framed paintings were intermediate between the images of the paintings and the museum scenes, i.e., the frames provided a transition between the paintings and their surround. We also observed differences between the three museums that may reflect modified frame usage in different art periods. For example, frames in the museum for 20th century art tended to be smaller and less complex than in the two other two museums that exhibit paintings from earlier art periods (13th-18th century and 19th century, respectively. Finally, we found that the three properties did not depend on the type of reproduction of the paintings (photographs in museums, scans from books or images from the Google Art Project. To the best of our knowledge, this study is the first to investigate the relation between frames and paintings by measuring physically defined, higher-order image properties.
Mechanical properties of fibroblasts depend on level of cancer transformation.
Efremov, Yu M; Lomakina, M E; Bagrov, D V; Makhnovskiy, P I; Alexandrova, A Y; Kirpichnikov, M P; Shaitan, K V
2014-05-01
Recently, it was revealed that tumor cells are significantly softer than normal cells. Although this phenomenon is well known, it is connected with many questions which are still unanswered. Among these questions are the molecular mechanisms which cause the change in stiffness and the correlation between cell mechanical properties and their metastatic potential. We studied mechanical properties of cells with different levels of cancer transformation. Transformed cells in three systems with different transformation types (monooncogenic N-RAS, viral and cells of tumor origin) were characterized according to their morphology, actin cytoskeleton and focal adhesion organization. Transformation led to reduction of cell spreading and thus decreasing the cell area, disorganization of actin cytoskeleton, lack of actin stress fibers and decline in the number and size of focal adhesions. These alterations manifested in a varying degree depending on type of transformation. Force spectroscopy by atomic force microscopy with spherical probes was carried out to measure the Young's modulus of cells. In all cases the Young's moduli were fitted well by log-normal distribution. All the transformed cell lines were found to be 40-80% softer than the corresponding normal ones. For the cell system with a low level of transformation the difference in stiffness was less pronounced than for the two other systems. This suggests that cell mechanical properties change upon transformation, and acquisition of invasive capabilities is accompanied by significant softening.
Applications of Statistical Physics to Understanding the Properties and Function of Noncoding DNA
Stanley, H. Eugene
2003-03-01
One of the most remarkable features of human DNA is that 97 percent is not coding for proteins [1]. Studying this noncoding DNA is important both for practical reasons (to distinguish it from the coding DNA as the human genome is sequenced), and for scientific reasons (why is the noncoding DNA present at all, if it appears to have little if any purpose?). In this talk we discuss new methods of analyzing coding and noncoding DNA in parallel, with a view to uncovering different statistical properties of the two kinds of DNA. We also speculate on possible roles of noncoding DNA. The work reported here was carried out in collaboration with P. Bernaola-Galvan, S. V. Buldyrev, P. Carpena, N. Dokholyan, A. L. Goldberger, A. L. Goldberger, I. Grosse, S. Havlin, H. Herzel, R. N. Mantegna, C.-K. Peng, M. Simons, R. H. R. Stanley, and G. M. Viswanathan. [1] For a brief overview in language that physicists can understand, see H. E. Stanley, S. V. Buldyrev, A. L. Goldberger, S. Havlin, C.-K. Peng, and M. Simons, "Scaling Features of Noncoding DNA" [Proc. XII Max Born Symposium, Wroclaw], Physica A 273, 1-18 (1999).
Zhou, Quan
2010-01-01
We present a systematic experimental study of geometric and statistical properties of thermal plumes in turbulent Rayleigh-B\\'{e}nard convection using the thermochromic-liquid-crystal (TLC) technique. The experiments were performed in three water-filled cylindrical convection cells with aspect ratios 2, 1, and 0.5 and over the Rayleigh-number range $5\\times10^7 \\leq Ra \\leq 10^{11}$. TLC thermal images of horizontal plane cuts at various depths below the top plate were acquired. Three-dimensional images of thermal plumes were then reconstructed from the two-dimensional slices of the temperature field. The results show that the often-called sheetlike plumes are really one-dimensional structures and may be called rodlike plumes. We find that the number densities for both sheetlike/rodlike and mushroomlike plumes have power-law dependence on $Ra$ with scaling exponents of $\\sim 0.3$, which is close to that between the Nusselt number $Nu$ and $Ra$. This result suggests that it is the plume number that primarily d...
Dultzin-Hacyan, D.; Ruano, C.
1996-01-01
We present a statistical study including principal component analysis (PCA) of multiwavelength properties of types 1 and 2 Seyfert galaxies. We have applied PCA to an ensemble of X-ray, optical, near and far infrared, and radio data of Seyfert galaxies. We used Lipovetsky et al. (1987) catalog which provides the largest list of Seyfert galaxies with multiwavelength data. Our main result is that the Spectral Energy Distribution (SED) of Seyfert 1 galaxies is well accounted by one and only one underlying variable, at least to a first approximation. On the other hand, in the case of Seyfert 2 galaxies, at least three variables are required. Several details of the analysis lead us to the following interpretation of this result: In the case of Seyfert 1 galaxies, the main process at the origin of radiation is the release of energy of gravitational origin by accretion unto a supermassive black hole. In the case of Seyfert 2 galaxies, there are other important processes apart from energy of gravitational origin, which we may identify with stellar and interstellar radiation (mainly dust absortion and re-emission) from the circumnuclear region. In the framework of this interpretation the analysis reveals that the variance in luminosity related to radiation of stellar/interstellar origin in no case exceeds ~13% for Seyfert 1 galaxies. In contrast, for Seyfert 2 galaxies the radiation of stellar/interstellar origin can account for ~46% of the variance in certain luminosities.
Modeling Statistical Properties of Solar Active Regions through DNS of 3D-MHD Turbulence
Malapaka, Shiva Kumar
2013-01-01
Statistical properties of the Sun's photospheric turbulent magnetic field, especially those of the Active Regions (ARs), have been studied using the line-of-sight data from magnetograms taken by SOHO and several other instruments (see e.g. Abramenko et al (2002, 2003),Abramenko and Yurchyshyn (2010)). This includes structure functions and their exponents, flatness curves and correlation functions. In these works, the dependence of structure function exponents ($\\zeta_p$) of the order of the structure functions ($\\it{p}$) was modeled using a non-intermittent K41 model. It is now well known that the ARs are highly turbulent and are associated with strong intermittent events. In this paper we compare some of the observations from Abramenko et al (2003) with the log-Poisson model (Biskamp 2003) used for modeling intermittent MHD turbulent flows. Next, we analyze the structure function data obtained from the direct numerical simulations (DNS) of homogeneous, incompressible 3D-MHD turbulence in three cases: sustain...
AGN and QSOs in the eROSITA All-Sky Survey -- Part I: Statistical properties
Kolodzig, Alexander; Sunyaev, Rashid; Sazonov, Sergey; Brusa, Marcella
2012-01-01
Context. The main element of the observing program of the Spectrum-Roentgen-Gamma orbital observatory is a 4-years all-sky survey in the course of which the entire sky will be scanned eight times. Aims. We analyze statistical properties of AGN and QSOs to be detected in the course of the eROSITA all-sky survey (eRASS). Methods. Given the currently planned survey strategy, parameters of the galactic and extragalactic X-ray background and results of the recent calculations of the eROSITA instrumental background, we compute the sensitivity map of the eRASS. Using the best available redshift-dependent AGN X-ray luminosity function (XLF) we compute various characteristics of the eRASS AGN sample, such as the luminosity and redshift distributions and the brightness distributions of their optical counterparts. Results. After four years of the survey, the sky-average sensitivity of ~10^(-14) erg s^(-1) cm^(-2) will be achieved in the 0.5-2.0 keV band. With this sensitivity, eROSITA will detect about ~3 million of AGN...
Statistical properties of damped Lyman-alpha systems from Sloan Digital Sky Survey DR12
Bird, Simeon; Garnett, Roman; Ho, Shirley
2017-04-01
We present new estimates for the statistical properties of damped Lyman-α absorbers (DLAs). We compute the column density distribution function at z > 2, the line density, dN/dX, and the neutral hydrogen density, ΩDLA. Our estimates are derived from the DLA catalogue of Garnett et al. (2016), which uses the Sloan Digital Sky Survey III Data Release 12 (SDSS-III DR12) quasar spectroscopic survey. This catalogue provides a probability that a given spectrum contains a DLA. It allows us to use even the noisiest data without biasing our results and thus substantially increases our sample size. We measure a non-zero column density distribution function at 95 per cent confidence for all column densities N_H I 4. We show that our results are insensitive to the signal-to-noise ratio of the spectra, but that there is a residual dependence on quasar redshift for z < 2.5, which may be due to remaining systematics in our analysis.
Entropy: An Inherent, Non-statistical Property of any System in any State
Directory of Open Access Journals (Sweden)
Elias P. Gyftopoulos
2006-09-01
Full Text Available
Entropy is the distinguishing and most important concept of our efforts to understand and regularize our observations of a very large class of natural phenomena, and yet, it is one of the most contentious concepts of physics. In this article, we review two expositions of thermodynamics, one without reference to quantum theory, and the other quantum mechanical without probabilities of statistical mechanics. In the first, we show that entropy is an inherent property of any system in any state, and that its analytical expression must conform to eight criteria. In the second, we recognize that quantum thermodynamics: (i admits quantum probabilities described either by wave functions or by nonstatistical density operators; and (ii requires a nonlinear equation of motion that is delimited by but more general than the Schrödinger equation, and that accounts for both reversible and irreversible evolutions of the state of the system in time. Both the more general quantum probabilities, and the equation of motion have been defined, and the three laws of thermodynamics are shown to be theorems of this equation.
Gorobtsov, O Yu; Brenner, G; Lorenz, U; Gerasimova, N; Kurta, R P; Hieke, F; Skopintsev, P; Zaluzhnyy, I; Lazarev, S; Dzhigaev, D; Rose, M; Singer, A; Wurth, W; Vartanyants, I A
2016-01-01
We present a comprehensive experimental analysis of statistical properties of the self-amplified spontaneous emission (SASE) free-electron laser (FEL) FLASH at DESY in Hamburg by means of Hanbury Brown and Twiss (HBT) interferometry. The experiments were performed at the FEL wavelengths of 5.5 nm, 13.4 nm, and 20.8 nm. We determined the 2-nd order intensity correlation function for all wavelengths and different operation conditions of FLASH. In all experiments a high degree of spatial coherence (above 50%) was obtained. Our analysis performed in spatial and spectral domains provided us with the independent measurements of an average pulse duration of the FEL that were below 60 fs. To explain complicated behaviour of the 2-nd order intensity correlation function we developed advanced theoretical model that includes the presence of multiple beams and external positional jitter of the FEL pulses. By this analysis we determined that in most experiments several beams were present in radiating field and in one of t...
Park, Jong-Hyeok; Kim, Ki-Beom; Chang, Heon-Young
2014-08-01
Time series of drought indices has been considered mostly in view of temporal and spatial distributions of a drought index so far. Here we investigate the statistical properties of a daily Effective Drought Index (EDI) itself for Seoul, Busan, Daegu, Mokpo for the period of 100 years from 1913 to 2012. We have found that both in dry and wet seasons the distribution of EDI as a function of EDI follows the Gaussian function. In dry season the shape of the Gaussian function is characteristically broader than that in wet seasons. The total number of drought days during the period we have analyzed is related both to the mean value and more importantly to the standard deviation. We have also found that according to the distribution of the number of occasions where the EDI values of several consecutive days are all less than a threshold, the distribution follows the exponential distribution. The slope of the best fit becomes steeper not only as the critical EDI value becomes more negative but also as the number of consecutive days increases. The slope of the exponential distribution becomes steeper as the number of the city in which EDI is simultaneously less than a critical EDI in a row increases. Finally, we conclude by pointing out implications of our findings.
Perrotta, Serena; Prochaska, J Xavier; Cristiani, Stefano; Cupani, Guido; Ellison, Sara; Lòpez, Sebastian; Becker, George D; Berg, Trystyn A M; Christensen, Lise; Denney, Kelly D; Hamann, Frederick; Pâris, Isabelle; Vestergaard, Marianne; Worseck, Gábor
2016-01-01
We statistically study the physical properties of a sample of narrow absorption line (NAL) systems looking for empirical evidences to distinguish between intrinsic and intervening NALs without taking into account any a priori definition or velocity cut-off. We analyze the spectra of 100 quasars with 3.5 < z$\\rm_{em}$ < 4.5, observed with X-shooter/VLT in the context of the XQ-100 Legacy Survey. We detect a $\\sim$ 8 $\\sigma$ excess in the number density of absorbers within 10,000 km/s of the quasar emission redshift with respect to the random occurrence of NALs. This excess does not show a dependence on the quasar bolometric luminosity and it is not due to the redshift evolution of NALs. It extends far beyond the standard 5000 km/s cut-off traditionally defined for associated absorption lines. We propose to modify this definition, extending the threshold to 10,000 km/s when also weak absorbers (equivalent width < 0.2 \\AA) are considered. We infer NV is the ion that better traces the effects of the qua...
Li, Duo-Fang; Cao, Tian-Guang; Geng, Jin-Peng; Gu, Jian-Zhong; An, Hai-Long; Zhan, Yong
2015-09-07
The stochastic Eigen model proposed by Feng et al. (2007) (Journal of Theoretical Biology, 246, 28) showed that error threshold is no longer a phase transition point but a crossover region whose width depends on the strength of the random fluctuation in an environment. The underlying cause of this phenomenon has not yet been well examined. In this article, we adopt a single peak Gaussian distributed fitness landscape instead of a constant one to investigate and analyze the change of the error threshold and the statistical property of the quasi-species population. We find a roughly linear relation between the width of the error threshold and the fitness fluctuation strength. For a given quasi-species, the fluctuation of the relative concentration has a minimum with a normal distribution of the relative concentration at the maximum of the averaged relative concentration, it has however a largest value with a bimodal distribution of the relative concentration near the error threshold. The above results deepen our understanding of the quasispecies and error threshold and are heuristic for exploring practicable antiviral strategies.
Monthus, Cécile
2017-03-01
For Anderson localization models with multifractal eigenvectors on disordered samples containing N sites, we analyze in a unified framework the consequences for the statistical properties of the Green function. We focus in particular on the imaginary part of the Green function at coinciding points GxxI≤ft(E-\\text{i}η \\right) and study the scaling with the size N of the moments of arbitrary indices q when the broadening follows the scaling η =\\frac{c}{{{N}δ}} . For the standard scaling regime δ =1 , we find in the two limits c\\ll 1 and c\\gg 1 that the moments are governed by the anomalous exponents Δ (q) of individual eigenfunctions, without the assumption of strong correlations between the weights of consecutive eigenstates at the same point. For the non-standard scaling regimes 0function follows some Fréchet distribution in the typical region, while rare events are important to obtain the scaling of the moments. We describe the application to the case of Gaussian multifractality and to the case of linear multifractality.
Statistical properties of the maximum Lyapunov exponent calculated via the divergence rate method.
Franchi, Matteo; Ricci, Leonardo
2014-12-01
The embedding of a time series provides a basic tool to analyze dynamical properties of the underlying chaotic system. To this purpose, the choice of the embedding dimension and lag is crucial. Although several methods have been devised to tackle the issue of the optimal setting of these parameters, a conclusive criterion to make the most appropriate choice is still lacking. An accepted procedure to rank different embedding methods relies on the evaluation of the maximum Lyapunov exponent (MLE) out of embedded time series that are generated by chaotic systems with explicit analytic representation. The MLE is evaluated as the local divergence rate of nearby trajectories. Given a system, embedding methods are ranked according to how close such MLE values are to the true MLE. This is provided by the so-called standard method in a way that exploits the mathematical description of the system and does not require embedding. In this paper we study the dependence of the finite-time MLE evaluated via the divergence rate method on the embedding dimension and lag in the case of time series generated by four systems that are widely used as references in the scientific literature. We develop a completely automatic algorithm that provides the divergence rate and its statistical uncertainty. We show that the uncertainty can provide useful information about the optimal choice of the embedding parameters. In addition, our approach allows us to find which systems provide suitable benchmarks for the comparison and ranking of different embedding methods.
Bianchi, L; Viton, M; Laget, M; Efremova, B; Herald, J; Conti, A; Shiao, B; De Paz, A G; Salim, S; Thakar, A; Friedman, P G; Rey, S C; Thilker, D; Barlow, T A; Budavari, T; Donas, J; Forster, K; Heckman, T M; Lee, Y W; Madore, B F; Martin, D C; Milliard, B; Morrissey, P; Neff, S G; Rich, R M; Schiminovich, D; Seibert, M; Small, T; Szalay, A S; Wyder, T K; Welsh, B Y; Yi, S K; Bianchi, Luciana; Rodriguez-Merino, Lino; Viton, Maurice; Laget, Michel; Efremova, Boryana; Herald, James; Conti, Alberto; Shiao, Bernie; Paz, Armando Gil de; Salim, Samir; Friedman, Peter G.; Thilker, David; Barlow, Tom A.; Budavari, Tamas; Donas, Jose; Forster, Karl; Heckman, Timothy M.; Lee, Young-Wook; Madore, Barry F.; Milliard, Bruno; Morrissey, Patrick; Neff, Susan G.; Schiminovich, David; Seibert, Mark; Small, Todd; Szalay, Alex S.; Wyder, Ted K.; Welsh, Barry Y.; Yi, Sukyoung K.
2006-01-01
We use the Galaxy Evolution Explorer (GALEX) Medium and All-Sky-Imaging Survey (MIS & AIS) data from the first public data release (GR1), matched to the Sloan Digital Sky Survey (SDSS) DR3 catalog, to perform source classification. The GALEX surveys provide photometry in far- and near-UV bands and the SDSS in five optical bands (u,g,r,i,z). The GR1/DR3 overlapping areas are 363[83]deg^2 for the GALEX AIS[MIS], for sources within the 0.5deg central area of the GALEX fields. Our sample covers mostly |b|>30deg galactic latitudes. We present statistical properties of the GALEX/SDSS matched sources catalog, containing >2x10^6 objects detected in at least one UV band. We classify the matched sources by comparing the seven-band photometry to model colors constructed for different classes of astrophysical objects. For sources with photometric errors <0.3 mag, the corresponding typical AB-magnitude limits are m_FUV~21.5, m_NUV~22.5 for AIS, and m_FUV~24, m_NUV~24.5 for MIS. At AIS depth, the number of Galactic ...
Directory of Open Access Journals (Sweden)
Masoud Ghodrati
2016-12-01
Full Text Available Humans are fast and accurate in categorizing complex natural images. It is, however, unclear what features of visual information are exploited by brain to perceive the images with such speed and accuracy. It has been shown that low-level contrast statistics of natural scenes can explain the variance of amplitude of event-related potentials (ERP in response to rapidly presented images. In this study, we investigated the effect of these statistics on frequency content of ERPs. We recorded ERPs from human subjects, while they viewed natural images each presented for 70 ms. Our results showed that Weibull contrast statistics, as a biologically plausible model, explained the variance of ERPs the best, compared to other image statistics that we assessed. Our time-frequency analysis revealed a significant correlation between these statistics and ERPs’ power within theta frequency band (~3-7 Hz. This is interesting, as theta band is believed to be involved in context updating and semantic encoding. This correlation became significant at ~110 ms after stimulus onset, and peaked at 138 ms. Our results show that not only the amplitude but also the frequency of neural responses can be modulated with low-level contrast statistics of natural images and highlights their potential role in scene perception.
DEFF Research Database (Denmark)
Stoica, Iuliana-Madalina; Babamoradi, Hamid; van den Berg, Frans
2017-01-01
•A statistical strategy combining fluorescence spectroscopy, multivariate analysis and Wilks’ ratio is proposed.•The method was tested both off-line and on-line having riboflavin as a (controlled) contaminant.•Wilks’ ratio signals unusual recordings based on shifts in variance and covariance stru...
Yang, Su
2005-02-01
A new descriptor for symbol recognition is proposed. 1) A histogram is constructed for every pixel to figure out the distribution of the constraints among the other pixels. 2) All the histograms are statistically integrated to form a feature vector with fixed dimension. The robustness and invariance were experimentally confirmed.
Replicate This! Creating Individual-Level Data from Summary Statistics Using R
Morse, Brendan J.
2013-01-01
Incorporating realistic data and research examples into quantitative (e.g., statistics and research methods) courses has been widely recommended for enhancing student engagement and comprehension. One way to achieve these ends is to use a data generator to emulate the data in published research articles. "MorseGen" is a free data generator that…
Land use in Eduador: a statistical analysis at different aggregation levels.
Koning, de G.H.J.; Veldkamp, A.; Fresco, L.O.
1998-01-01
Land use in Ecuador was investigated by means of statistical analysis with the purpose of deriving quantitative estimates of the relative areas of land use types on the basis of biogeophysical, socio-economic and infrastructural conditions. The smallest spatial units of investigation were 5 by 5 min
Changing Statistical Significance with the Amount of Information: The Adaptive α Significance Level.
Pérez, María-Eglée; Pericchi, Luis Raúl
2014-02-01
We put forward an adaptive alpha which changes with the amount of sample information. This calibration may be interpreted as a Bayes/non-Bayes compromise, and leads to statistical consistency. The calibration can also be used to produce confidence intervals whose size take in consideration the amount of observed information.
Gofford, Jason; Reeves, James N.; Tombesi, Francesco; Braito, Valentina; Turner, T. Jane; Miller, Lance; Cappi, Massimo
2013-01-01
We present the results of a new spectroscopic study of Fe K-band absorption in active galactic nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically driven blind search for Fe XXV Healpha and/or Fe XXVI Lyalpha absorption lines in a large sample of 51 Type 1.0-1.9 AGN. Through extensive Monte Carlo simulations we find that statistically significant absorption is detected at E greater than or approximately equal to 6.7 keV in 20/51 sources at the P(sub MC) greater than or equal tov 95 per cent level, which corresponds to approximately 40 per cent of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available X-ray imaging spectrometer detectors, which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe XXV Healpha and Fe XXVI Lyalpha at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the Fe K absorption components are log (N(sub H) per square centimeter)) is approximately equal to 23 and log (Xi/erg centimeter per second) is approximately equal to 4.5, respectively. Measured outflow velocities span a continuous range from less than1500 kilometers per second up to approximately100 000 kilometers per second, with mean and median values of approximately 0.1 c and approximately 0.056 c, respectively. The results of this work are consistent with those recently obtained using XMM-Newton and independently provides strong evidence for the existence of very highly ionized circumnuclear material in a significant fraction of both radio-quiet and radio-loud AGN in the local universe.
Cluster survey of the high-altitude cusp properties: a three-year statistical study
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B. Lavraud
2004-09-01
Full Text Available The global characteristics of the high-altitude cusp and its surrounding regions are investigated using a three-year statistical survey based on data obtained by the Cluster spacecraft. The analysis involves an elaborate orbit-sampling methodology that uses a model field and takes into account the actual solar wind conditions and level of geomagnetic activity. The spatial distribution of the magnetic field and various plasma parameters in the vicinity of the low magnetic field exterior cusp are determined and it is found that: 1 The magnetic field distribution shows the presence of an intermediate region between the magnetosheath and the magnetosphere: the exterior cusp, 2 This region is characterized by the presence of dense plasma of magnetosheath origin; a comparison with the Tsyganenko (1996 magnetic field model shows that it is diamagnetic in nature, 3 The spatial distributions show that three distinct boundaries with the lobes, the dayside plasma sheet and the magnetosheath surround the exterior cusp, 4 The external boundary with the magnetosheath has a sharp bulk velocity gradient, as well as a density decrease and temperature increase as one goes from the magnetosheath to the exterior cusp, 5 While the two inner boundaries form a funnel, the external boundary shows no clear indentation, 6 The plasma and magnetic pressure distributions suggest that the exterior cusp is in equilibrium with its surroundings in a statistical sense, and 7 A preliminary analysis of the bulk flow distributions suggests that the exterior cusp is stagnant under northward IMF conditions but convective under southward IMF conditions.
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Dodonov, A.V., E-mail: adodonov@fis.unb.br [Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70910-900 Brasília, DF (Brazil); Dodonov, V.V., E-mail: vdodonov@fis.unb.br [Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70910-900 Brasília, DF (Brazil)
2011-11-21
We study numerically the evolution of the cavity electromagnetic field mode which is in resonance with an oscillating boundary (dynamical Casimir effect), taking into account the interaction between the field and a two-level atom, that may or not be continuously monitored by a coupled atomic excitation detector. We analyze the behavior of the field statistics and the quadrature squeezing properties in different regimes, demonstrating that at the expense of decreasing the number of produced photons and the degree of squeezing, one can create qualitatively new types of cavity field states. -- Highlights: ► We study the statistics of photons created in a cavity via dynamical Casimir effect. ► We take into account the interaction with a two-level atom placed inside the cavity. ► The field–atom dynamics is calculated numerically for the Rabi coupling. ► The interaction with a detector can totally change the statistics of created photons. ► The statistics can vary from weakly super-Poissonian to strong “hyper-Poissonian”.
Restoration and enhancement of textural properties in SAR images using second-order statistics
Nezry, Edmond; Kohl, Hans-Guenther; De Groof, Hugo
1994-12-01
Local second order properties, describing spatial relations between pixels are introduced into the single-point speckle adaptive filtering processes, in order to account for the effects of speckle spatial correlation and to enhance scene textural properties in the restored image. To this end, texture measures originating, first from local grey level co-occurrence matrices (GLCM), and second from the local autocorrelation functions (ACF) are used. Results obtained on 3-look processed ERS-1 FDC and PRI spaceborne images illustrate the performance allowed by the introduction of these texture measures in the structure retaining speckle adaptive filters. The observable texture in remote sensing images is related to the physical spatial resolution of the sensor. For this reason, other spatial speckle decorrelation methods, more simple and easier to implement, for example post-filtering and linear image resampling, are also presented in this paper. In the particular case of spaceborne SAR imagery, all these methods lead to visually similar results. They produce filtered (radar reflectivity) images visually comparable to optical images.
Meta-analysis of gene-level associations for rare variants based on single-variant statistics.
Hu, Yi-Juan; Berndt, Sonja I; Gustafsson, Stefan; Ganna, Andrea; Hirschhorn, Joel; North, Kari E; Ingelsson, Erik; Lin, Dan-Yu
2013-08-08
Meta-analysis of genome-wide association studies (GWASs) has led to the discoveries of many common variants associated with complex human diseases. There is a growing recognition that identifying "causal" rare variants also requires large-scale meta-analysis. The fact that association tests with rare variants are performed at the gene level rather than at the variant level poses unprecedented challenges in the meta-analysis. First, different studies may adopt different gene-level tests, so the results are not compatible. Second, gene-level tests require multivariate statistics (i.e., components of the test statistic and their covariance matrix), which are difficult to obtain. To overcome these challenges, we propose to perform gene-level tests for rare variants by combining the results of single-variant analysis (i.e., p values of association tests and effect estimates) from participating studies. This simple strategy is possible because of an insight that multivariate statistics can be recovered from single-variant statistics, together with the correlation matrix of the single-variant test statistics, which can be estimated from one of the participating studies or from a publicly available database. We show both theoretically and numerically that the proposed meta-analysis approach provides accurate control of the type I error and is as powerful as joint analysis of individual participant data. This approach accommodates any disease phenotype and any study design and produces all commonly used gene-level tests. An application to the GWAS summary results of the Genetic Investigation of ANthropometric Traits (GIANT) consortium reveals rare and low-frequency variants associated with human height. The relevant software is freely available.
Soil properties discriminating Araucaria forests with different disturbance levels.
Bertini, Simone Cristina Braga; Azevedo, Lucas Carvalho Basilio; Stromberger, Mary E; Cardoso, Elke Jurandy Bran Nogueira
2015-04-01
Soil biological, chemical, and physical properties can be important for monitoring soil quality under one of the most spectacular vegetation formation on Atlantic Forest Biome, the Araucaria Forest. Our aim was to identify a set of soil variables capable of discriminating between disturbed, reforested, and native Araucaria forest soils such that these variables could be used to monitor forest recovery and maintenance. Soil samples were collected at dry and rainy season under the three forest types in two state parks at São Paulo State, Brazil. Soil biological, chemical, and physical properties were evaluated to verify their potential to differentiate the forest types, and discriminant analysis was performed to identify the variables that most contribute to the differentiation. Most of physical and chemical variables were sensitive to forest disturbance level, but few biological variables were significantly different when comparing native, reforested, and disturbed forests. Despite more than 20 years following reforestation, the reforested soils were chemically and biologically distinct from native and disturbed forest soils, mainly because of the greater acidity and Al3+ content of reforested soil. Disturbed soils, in contrast, were coarser in texture and contained greater concentrations of extractable P. Although biological properties are generally highly sensitive to disturbance and amelioration efforts, the most important soil variables to discriminate forest types in both seasons included Al3+, Mg2+, P, and sand, and only one microbial attribute: the NO2- oxidizers. Therefore, these five variables were the best candidates, of the variables we employed, for monitoring Araucaria forest disturbance and recovery.
A new formula for the statistical weight for a sequence of Rydberg levels in an atom or ion
Eriksson, M.; Lennerstad, H.
2017-07-01
We present a new formula for the total statistical weight of all Rydberg levels Gion (nl, nh ) for which the principal quantum number n is between higher, nh , and a lower, nl , limits. This formula can be used for all atoms in the periodic table and for all corresponding ions.
Wagler, Amy E.; Lesser, Lawrence M.; González, Ariel I.; Leal, Luis
2015-01-01
A corpus of current editions of statistics textbooks was assessed to compare aspects and levels of readability for the topics of "measures of center," "line of fit," "regression analysis," and "regression inference." Analysis with lexical software of these text selections revealed that the large corpus can…
de Wieclawik, W; Vieu, C
1976-01-01
The Ericson's statistical method is applied extensively to the analysis of experimental and theoretical negative parity levels of odd mass Tl, Au and Ir isotopes. This analysis shows the importance of such method as a valuable tool for detecting systematic insufficiencies of experimental data as well as for testing the overall descriptions of a nucleus given by different nuclear models.
SUPERFLARES ON SOLAR-TYPE STARS OBSERVED WITH KEPLER. I. STATISTICAL PROPERTIES OF SUPERFLARES
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Shibayama, Takuya; Notsu, Shota; Notsu, Yuta; Nagao, Takashi [Department of Astronomy, Kyoto University, Sakyo, Kyoto 606-8502 (Japan); Maehara, Hiroyuki; Honda, Satoshi; Ishii, Takako T.; Nogami, Daisaku; Shibata, Kazunari, E-mail: shibayama@kwasan.kyoto-u.ac.jp [Kwasan and Hida Observatory, Kyoto University, Yamashina, Kyoto 607-8471 (Japan)
2013-11-01
By extending our previous study by Maehara et al., we searched for superflares on G-type dwarfs (solar-type stars) using Kepler data for a longer period (500 days) than that (120 days) in our previous study. As a result, we found 1547 superflares on 279 G-type dwarfs, which is much more than the previous 365 superflares on 148 stars. Using these new data, we studied the statistical properties of the occurrence rate of superflares, and confirmed the previous results, i.e., the occurrence rate (dN/dE) of superflares versus flare energy (E) shows a power-law distribution with dN/dE∝E {sup –α}, where α ∼ 2. It is interesting that this distribution is roughly similar to that for solar flares. In the case of the Sun-like stars (with surface temperature 5600-6000 K and slowly rotating with a period longer than 10 days), the occurrence rate of superflares with an energy of 10{sup 34}-10{sup 35} erg is once in 800-5000 yr. We also studied long-term (500 days) stellar brightness variation of these superflare stars and found that in some G-type dwarfs the occurrence rate of superflares was extremely high, ∼57 superflares in 500 days (i.e., once in 10 days). In the case of Sun-like stars, the most active stars show a frequency of one superflare (with 10{sup 34} erg) in 100 days. There is evidence that these superflare stars have extremely large starspots with a size about 10 times larger than that of the largest sunspot. We argue that the physical origin of the extremely high occurrence rate of superflares in these stars may be attributed to the existence of extremely large starspots.
Dynamic range adaptation to sound level statistics in the auditory nerve.
Wen, Bo; Wang, Grace I; Dean, Isabel; Delgutte, Bertrand
2009-11-04
The auditory system operates over a vast range of sound pressure levels (100-120 dB) with nearly constant discrimination ability across most of the range, well exceeding the dynamic range of most auditory neurons (20-40 dB). Dean et al. (2005) have reported that the dynamic range of midbrain auditory neurons adapts to the distribution of sound levels in a continuous, dynamic stimulus by shifting toward the most frequently occurring level. Here, we show that dynamic range adaptation, distinct from classic firing rate adaptation, also occurs in primary auditory neurons in anesthetized cats for tone and noise stimuli. Specifically, the range of sound levels over which firing rates of auditory nerve (AN) fibers grows rapidly with level shifts nearly linearly with the most probable levels in a dynamic sound stimulus. This dynamic range adaptation was observed for fibers with all characteristic frequencies and spontaneous discharge rates. As in the midbrain, dynamic range adaptation improved the precision of level coding by the AN fiber population for the prevailing sound levels in the stimulus. However, dynamic range adaptation in the AN was weaker than in the midbrain and not sufficient (0.25 dB/dB, on average, for broadband noise) to prevent a significant degradation of the precision of level coding by the AN population above 60 dB SPL. These findings suggest that adaptive processing of sound levels first occurs in the auditory periphery and is enhanced along the auditory pathway.
Khandekar, D.C.; Wiegel, F.W.
1993-01-01
The statistical mechanical properties of plane polymer configurations which enclose a fixed area and are subject to an external electric field are investigated. For this purpose an exact expression for the generating functional is obtained and subsequently used to derive: (a) the distribution functi
Directory of Open Access Journals (Sweden)
Claudia Menzel
Full Text Available We investigated whether low-level processed image properties that are shared by natural scenes and artworks - but not veridical face photographs - affect the perception of facial attractiveness and age. Specifically, we considered the slope of the radially averaged Fourier power spectrum in a log-log plot. This slope is a measure of the distribution of special frequency power in an image. Images of natural scenes and artworks possess - compared to face images - a relatively shallow slope (i.e., increased high spatial frequency power. Since aesthetic perception might be based on the efficient processing of images with natural scene statistics, we assumed that the perception of facial attractiveness might also be affected by these properties. We calculated Fourier slope and other beauty-associated measurements in face images and correlated them with ratings of attractiveness and age of the depicted persons (Study 1. We found that Fourier slope - in contrast to the other tested image properties - did not predict attractiveness ratings when we controlled for age. In Study 2A, we overlaid face images with random-phase patterns with different statistics. Patterns with a slope similar to those in natural scenes and artworks resulted in lower attractiveness and higher age ratings. In Studies 2B and 2C, we directly manipulated the Fourier slope of face images and found that images with shallower slopes were rated as more attractive. Additionally, attractiveness of unaltered faces was affected by the Fourier slope of a random-phase background (Study 3. Faces in front of backgrounds with statistics similar to natural scenes and faces were rated as more attractive. We conclude that facial attractiveness ratings are affected by specific image properties. An explanation might be the efficient coding hypothesis.
Menzel, Claudia; Hayn-Leichsenring, Gregor U; Langner, Oliver; Wiese, Holger; Redies, Christoph
2015-01-01
We investigated whether low-level processed image properties that are shared by natural scenes and artworks - but not veridical face photographs - affect the perception of facial attractiveness and age. Specifically, we considered the slope of the radially averaged Fourier power spectrum in a log-log plot. This slope is a measure of the distribution of special frequency power in an image. Images of natural scenes and artworks possess - compared to face images - a relatively shallow slope (i.e., increased high spatial frequency power). Since aesthetic perception might be based on the efficient processing of images with natural scene statistics, we assumed that the perception of facial attractiveness might also be affected by these properties. We calculated Fourier slope and other beauty-associated measurements in face images and correlated them with ratings of attractiveness and age of the depicted persons (Study 1). We found that Fourier slope - in contrast to the other tested image properties - did not predict attractiveness ratings when we controlled for age. In Study 2A, we overlaid face images with random-phase patterns with different statistics. Patterns with a slope similar to those in natural scenes and artworks resulted in lower attractiveness and higher age ratings. In Studies 2B and 2C, we directly manipulated the Fourier slope of face images and found that images with shallower slopes were rated as more attractive. Additionally, attractiveness of unaltered faces was affected by the Fourier slope of a random-phase background (Study 3). Faces in front of backgrounds with statistics similar to natural scenes and faces were rated as more attractive. We conclude that facial attractiveness ratings are affected by specific image properties. An explanation might be the efficient coding hypothesis.
Assaraf, Roland; Domin, Dominik
2014-03-01
We study the efficiency of quantum Monte Carlo (QMC) methods in computing space localized ground state properties (properties which do not depend on distant degrees of freedom) as a function of the system size N. We prove that for the commonly used correlated sampling with reweighting method, the statistical fluctuations σ2(N) do not obey the locality property. σ2(N) grow at least linearly with N and with a slope that is related to the fluctuations of the reweighting factors. We provide numerical illustrations of these tendencies in the form of QMC calculations on linear chains of hydrogen atoms.
Afonine, Pavel V; Grosse-Kunstleve, Ralf W; Chen, Vincent B; Headd, Jeffrey J; Moriarty, Nigel W; Richardson, Jane S; Richardson, David C; Urzhumtsev, Alexandre; Zwart, Peter H; Adams, Paul D
2010-08-01
phenix.model_vs_data is a high-level command-line tool for the computation of crystallographic model and data statistics, and the evaluation of the fit of the model to data. Analysis of all Protein Data Bank structures that have experimental data available shows that in most cases the reported statistics, in particular R factors, can be reproduced within a few percentage points. However, there are a number of outliers where the recomputed R values are significantly different from those originally reported. The reasons for these discrepancies are discussed.
Statistical analysis of global surface air temperature and sea level using cointegration methods
DEFF Research Database (Denmark)
Schmith, Torben; Johansen, Søren; Thejll, Peter
Global sea levels are rising which is widely understood as a consequence of thermal expansion and melting of glaciers and land-based ice caps. Due to physically-based models being unable to simulate observed sea level trends, semi-empirical models have been applied as an alternative for projecting...
Heidel, R. Eric
2016-01-01
Statistical power is the ability to detect a significant effect, given that the effect actually exists in a population. Like most statistical concepts, statistical power tends to induce cognitive dissonance in hepatology researchers. However, planning for statistical power by an a priori sample size calculation is of paramount importance when designing a research study. There are five specific empirical components that make up an a priori sample size calculation: the scale of measurement of the outcome, the research design, the magnitude of the effect size, the variance of the effect size, and the sample size. A framework grounded in the phenomenon of isomorphism, or interdependencies amongst different constructs with similar forms, will be presented to understand the isomorphic effects of decisions made on each of the five aforementioned components of statistical power. PMID:27073717
Directory of Open Access Journals (Sweden)
R. Eric Heidel
2016-01-01
Full Text Available Statistical power is the ability to detect a significant effect, given that the effect actually exists in a population. Like most statistical concepts, statistical power tends to induce cognitive dissonance in hepatology researchers. However, planning for statistical power by an a priori sample size calculation is of paramount importance when designing a research study. There are five specific empirical components that make up an a priori sample size calculation: the scale of measurement of the outcome, the research design, the magnitude of the effect size, the variance of the effect size, and the sample size. A framework grounded in the phenomenon of isomorphism, or interdependencies amongst different constructs with similar forms, will be presented to understand the isomorphic effects of decisions made on each of the five aforementioned components of statistical power.
Directory of Open Access Journals (Sweden)
Nelson Hauck Filho
2014-12-01
Full Text Available Researchers dealing with the task of estimating locations of individuals on continuous latent variables may rely on several statistical models described in the literature. However, weighting costs and benefits of using one specific model over alternative models depends on empirical information that is not always clearly available. Therefore, the aim of this simulation study was to compare the performance of seven popular statistical models in providing adequate latent trait estimates in conditions of items difficulties targeted at the sample mean or at the tails of the latent trait distribution. Results suggested an overall tendency of models to provide more accurate estimates of true latent scores when using items targeted at the sample mean of the latent trait distribution. Rating Scale Model, Graded Response Model, and Weighted Least Squares Mean- and Variance-adjusted Confirmatory Factor Analysis yielded the most reliable latent trait estimates, even when applied to inadequate items for the sample distribution of the latent variable. These findings have important implications concerning some popular methodological practices in Psychology and related areas.
Statistical properties of diffuse Lyα haloes around star-forming galaxies at z ˜ 2
Momose, Rieko; Ouchi, Masami; Nakajima, Kimihiko; Ono, Yoshiaki; Shibuya, Takatoshi; Shimasaku, Kazuhiro; Yuma, Suraphong; Mori, Masao; Umemura, Masayuki
2016-04-01
We present statistical properties of diffuse Lyα haloes (LAHs) around high-z star-forming galaxies with large Subaru samples of Lyα emitters (LAEs) at z = 2.2. We make subsamples defined by the physical quantities of LAEs' central Lyα luminosities, ultraviolet (UV) magnitudes, Lyα equivalent widths, and UV slopes, and investigate LAHs' radial surface brightness (SB) profiles and scale lengths rn as a function of these physical quantities. We find that there exist prominent LAHs around LAEs with faint Lyα luminosities, bright UV luminosities, and small Lyα equivalent widths in cumulative radial Lyα SB profiles. We confirm this trend with the anticorrelation between rn and Lyα luminosities (equivalent widths) based on the Spearman's rank correlation coefficient that is ρ = -0.9 (-0.7) corresponding to the 96 per cent (93 per cent) confidence level, although the correlation between rn and UV magnitudes is not clearly found in the rank correlation coefficient. Our results suggest that LAEs with properties similar to typical Lyman-break galaxies (with faint Lyα luminosities and small equivalent widths) possess more prominent LAHs. We investigate scenarios for the major physical origins of LAHs with our results. Because we find relatively small Lyα equivalent widths up to 77 Å in LAHs that include LAEs' central components, these results suggest that the cold stream scenario is not preferred. There remain two possible scenarios of Lyα scattering in circumgalactic medium and satellite galaxies that cannot be tested with our observational data.
Statistical modeling and trend detection of extreme sea level records in the Pearl River Estuary
Wang, Weiwen; Zhou, Wen
2017-03-01
Sea level rise has become an important issue in global climate change studies. This study investigates trends in sea level records, particularly extreme records, in the Pearl River Estuary, using measurements from two tide gauge stations in Macau and Hong Kong. Extremes in the original sea level records (daily higher high water heights) and in tidal residuals with and without the 18.6-year nodal modulation are investigated separately. Thresholds for defining extreme sea levels are calibrated based on extreme value theory. Extreme events are then modeled by peaks-over-threshold models. The model applied to extremes in original sea level records does not include modeling of their durations, while a geometric distribution is added to model the duration of extremes in tidal residuals. Realistic modeling results are recommended in all stationary models. Parametric trends of extreme sea level records are then introduced to nonstationary models through a generalized linear model framework. The result shows that, in recent decades, since the 1960s, no significant trends can be found in any type of extreme at any station, which may be related to a reduction in the influence of tropical cyclones in the region. For the longer-term record since the 1920s at Macau, a regime shift of tidal amplitudes around the 1970s may partially explain the diverse trend of extremes in original sea level records and tidal residuals.
Lindblad, M; Börjesson, T; Hietaniemi, V; Elen, O
2012-01-01
The relationship between weather data and agronomical factors and deoxynivalenol (DON) levels in oats was examined with the aim of developing a predictive model. Data were collected from a total of 674 fields during periods of up to 10 years in Finland, Norway and Sweden, and included DON levels in the harvested oats crop, agronomical factors and weather data. The results show that there was a large regional variation in DON levels, with higher levels in one region in Norway compared with other regions in Norway, Finland and Sweden. In this region the median DON level was 1000 ng g⁻¹ and the regulatory limit for human consumption (1750 ng g⁻¹) was exceeded in 28% of the samples. In other regions the median DON levels ranged from 75 to 270 ng g⁻¹, and DON levels exceeded 1750 ng g⁻¹ in 3-8% of the samples. Including more variables than region in a multiple regression model only increased the adjusted coefficient of determination from 0.17 to 0.24, indicating that very little of the variation in DON levels could be explained by weather data or agronomical factors. Thus, it was not possible to predict DON levels based on the variables included in this study. Further studies are needed to solve this problem. Apparently the infection and/or growth of DON producing Fusarium species are promoted in certain regions. One possibility may be to study the species distribution of fungal communities and their changes during the oats cultivation period in more detail.
Energy Technology Data Exchange (ETDEWEB)
Eberhardt, L.L.; Thomas, J.M.
1986-07-01
This project was designed to develop guidance for implementing 10 CFR Part 61 and to determine the overall needs for sampling and statistical work in characterizing, surveying, monitoring, and closing commercial low-level waste sites. When cost-effectiveness and statistical reliability are of prime importance, then double sampling, compositing, and stratification (with optimal allocation) are identified as key issues. If the principal concern is avoiding questionable statistical practice, then the applicability of kriging (for assessing spatial pattern), methods for routine monitoring, and use of standard textbook formulae in reporting monitoring results should be reevaluated. Other important issues identified include sampling for estimating model parameters and the use of data from left-censored (less than detectable limits) distributions.
Dietary levels of acrylamide affect rat cardiomyocyte properties.
Walters, Brandan; Hariharan, Venkatesh; Huang, Hayden
2014-09-01
The toxic effects of acrylamide on cytoskeletal integrity and ion channel balance is well-established in many cell types, but there has been little examination regarding the effects of acrylamide on primary cardiomyocytes, despite the importance of such components in their function. Furthermore, acrylamide toxicity is generally examined using concentrations higher than those found in vivo under starch-rich diets. Accordingly, we sought to characterize the dose-dependent effects of acrylamide on various properties, including cell morphology, contraction patterns, and junctional connexin 43 staining, in primary cardiomyocytes. We show that several days exposure to 1-100 μM acrylamide resulted in altered morphology, irregular contraction patterns, and an increase in the amount of immunoreactive signal for connexin 43 at cell junctions. We conclude that dietary levels of acrylamide may alter cellular function with prolonged exposure, in primary cardiomyocytes. Copyright © 2014 Elsevier Ltd. All rights reserved.
Polymer extension under flow: Some statistical properties of the work distribution function
Ghosal, Aishani; Cherayil, Binny J.
2016-11-01
In an extension of earlier studies from this group on the application of the Jarzynski equality to the determination of the elastic properties of a finitely extensible Rouse model of polymers under flow [A. Ghosal and B. J. Cherayil, J. Chem. Phys. 144, 214902 (2016)], we derive several new theoretical results in this paper on the nature of the distribution function P (w ) that governs the long-time limit t >>1 of the fluctuations in the work w performed by the polymer during flow-induced stretching. In particular, we show that an expression for the average of the nth power of the work, ⟨wn(t ) ⟩ , can be obtained in closed form in this limit, making it possible to exactly calculate three important statistical measures of P (w ) : the mean μ, the skewness γ1, and the kurtosis γ2 (apart from the variance σ2). We find, for instance, that to leading order in t, the mean grows linearly with t at a constant value of the dimensionless flow rate Wi and that the slope of the μ -t curve increases with increasing Wi. These observations are in complete qualitative agreement with data from Brownian dynamics simulations of flow-driven double-stranded DNA by Latinwo and Schroeder [Macromolecules 46, 8345 (2013)]. We also find that the skewness γ1 exhibits an interesting inversion of sign as a function of Wi, starting off at positive values at low Wi and changing to negative values at larger Wi. The inversion takes place in the vicinity of what we interpret as a coil-stretch transition. Again, the finding exactly reproduces behavior seen in other numerical and experimental work by the above group Latinwo et al. [J. Chem. Phys. 141, 174903 (2014)]. Additionally, at essentially the same value of Wi at which this sign inversion takes place, we observe that the kurtosis reaches a minimum, close to 1, providing further evidence of the existence of a coil-stretch transition at this location. Our calculations reproduce another numerical finding: a power law dependence on Wi of
Cafaro, C
2008-01-01
In this paper, we review our novel information geometrodynamical approach to chaos (IGAC) on curved statistical manifolds and we emphasize the usefulness of our information-geometrodynamical entropy (IGE) as an indicator of chaoticity in a simple application. Furthermore, knowing that integrable and chaotic quantum antiferromagnetic Ising chains are characterized by asymptotic logarithmic and linear growths of their operator space entanglement entropies, respectively, we apply our IGAC to present an alternative characterization of such systems. Remarkably, we show that in the former case the IGE exhibits asymptotic logarithmic growth while in the latter case the IGE exhibits asymptotic linear growth. At this stage of its development, IGAC remains an ambitious unifying information-geometric theoretical construct for the study of chaotic dynamics with several unsolved problems. However, based on our recent findings, we believe it could provide an interesting, innovative and potentially powerful way to study and...
Cafaro, C.; Ali, S. A.
2008-12-01
In this paper, we review our novel information-geometrodynamical approach to chaos (IGAC) on curved statistical manifolds and we emphasize the usefulness of our information-geometrodynamical entropy (IGE) as an indicator of chaoticity in a simple application. Furthermore, knowing that integrable and chaotic quantum antiferromagnetic Ising chains are characterized by asymptotic logarithmic and linear growths of their operator space entanglement entropies, respectively, we apply our IGAC to present an alternative characterization of such systems. Remarkably, we show that in the former case the IGE exhibits asymptotic logarithmic growth while in the latter case the IGE exhibits asymptotic linear growth. At this stage of its development, IGAC remains an ambitious unifying information-geometric theoretical construct for the study of chaotic dynamics with several unsolved problems. However, based on our recent findings, we believe that it could provide an interesting, innovative and potentially powerful way to study and understand the very important and challenging problems of classical and quantum chaos.
An ISP Level Solution to Combat DDoS Attacks using Combined Statistical Based Approach
Gupta, B B; Joshi, R C
2012-01-01
Disruption from service caused by DDoS attacks is an immense threat to Internet today. These attacks can disrupt the availability of Internet services completely, by eating either computational or communication resources through sheer volume of packets sent from distributed locations in a coordinated manner or graceful degradation of network performance by sending attack traffic at low rate. In this paper, we describe a novel framework that deals with the detection of variety of DDoS attacks by monitoring propagation of abrupt traffic changes inside ISP Domain and then characterizes flows that carry attack traffic. Two statistical metrics namely, Volume and Flow are used as parameters to detect DDoS attacks. Effectiveness of an anomaly based detection and characterization system highly depends on accuracy of threshold value settings. Inaccurate threshold values cause a large number of false positives and negatives. Therefore, in our scheme, Six-Sigma and varying tolerance factor methods are used to identify t...
Chou, Cheng-Ying; Huang, Pin-Yu
2011-11-21
X-ray phase-contrast tomography (PCT) methods seek to quantitatively reconstruct separate images that depict an object's absorption and refractive contrasts. Most PCT reconstruction algorithms generally operate by explicitly or implicitly performing the decoupling of the projected absorption and phase properties at each tomographic view angle by use of a phase-retrieval formula. However, the presence of zero-frequency singularity in the Fourier-based phase retrieval formulas will lead to a strong noise amplification in the projection estimate and the subsequent refractive image obtained using conventional algorithms like filtered backprojection (FBP). Tomographic reconstruction by use of statistical methods can account for the noise model and a priori information, and thereby can produce images with better quality over conventional filtered backprojection algorithms. In this work, we demonstrate an iterative image reconstruction method that exploits the second-order statistical properties of the projection data can mitigate noise amplification in PCT. The autocovariance function of the reconstructed refractive images was empirically computed and shows smaller and shorter noise correlation compared to those obtained using the FBP and unweighted penalized least-squares methods. Concepts from statistical decision theory are applied to demonstrate that the statistical properties of images produced by our method can improve signal detectability.
Statistical properties of indicators of first-year performance at university
African Journals Online (AJOL)
Science and Numeracy Skills) have statistical distributions similar to that of average first- ... those admitted to the Arts, Theology, Law or Education Faculties wrote Test Battery 3. ..... predict average first-year university performance realistically.
Huang, Y C; Zhang, N
2004-01-01
Classical statistical average values are generally generalized to average values of quantum mechanics, it is discovered that quantum mechanics is direct generalization of classical statistical mechanics, and we generally deduce both a general new continuous eigenvalue equation and a general discrete eigenvalue equation in quantum mechanics, and discover that a eigenvalue of quantum mechanics is just an extreme value of an operator in possibility distribution, the eigenvalue f is just classical observable quantity. A general classical statistical uncertain relation is further given, the general classical statistical uncertain relation is generally generalized to quantum uncertainty principle, the two lost conditions in classical uncertain relation and quantum uncertainty principle, respectively, are found. We generally expound the relations among uncertainty principle, singularity and condensed matter stability, discover that quantum uncertainty principle prevents from the appearance of singularity of the elec...
P, C and T: Different Properties on the Kinematical Level
Dvoeglazov, Valeriy V
2016-01-01
We study the discrete symmetries (P,C and T) on the kinematical level within the extended Poincare Group. On the basis of the Silagadze research, we investigate the question of the definitions of the discrete symmetry operators both on the classical level, and in the secondary-quantization scheme. We study the physical contents within several bases: light-front formulation, helicity basis, angular momentum basis, and so on, on several practical examples. We analise problems in construction of the neutral particles in the the (1/2,0)+(0,1/2) representation, the (1,0)+(0,1) and the (1/2,1/2) representations of the Lorentz Group. As well known, the photon has the quantum numbers 1^-, so the (1,0)+(0,1) representation of the Lorentz group is relevant to its description. We have ambiguities in the definitions of the corresponding operators P, C; T, which lead to different physical consequences. It appears that the answers are connected with the helicity basis properties, and commutations/anticommutations of the co...
Sub-Poissonian phonon statistics in an acoustical resonator coupled to a pumped two-level emitter
Energy Technology Data Exchange (ETDEWEB)
Ceban, V., E-mail: victor.ceban@phys.asm.md; Macovei, M. A., E-mail: macovei@phys.asm.md [Academy of Sciences of Moldova, Institute of Applied Physics (Moldova, Republic of)
2015-11-15
The concept of an acoustical analog of the optical laser has been developed recently in both theoretical and experimental works. We here discuss a model of a coherent phonon generator with a direct signature of the quantum properties of sound vibrations. The considered setup is made of a laser-driven quantum dot embedded in an acoustical nanocavity. The system dynamics is solved for a single phonon mode in the steady-state and in the strong quantum dot—phonon coupling regime beyond the secular approximation. We demonstrate that the phonon statistics exhibits quantum features, i.e., is sub-Poissonian.
Energy Technology Data Exchange (ETDEWEB)
Wang, Z.M. [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China); Xue, H.B. [College of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Xue, N.T. [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China); Liang, J.-Q., E-mail: jqliang@sxu.edu.cn [Institute of Theoretical Physics and Department of Physics, Shanxi University, Taiyuan 030006 (China)
2015-02-15
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling.
Directory of Open Access Journals (Sweden)
Todd L Bredbenner
2014-11-01
Full Text Available Cervical spinal injuries are a significant concern in all trauma injuries. Recent military conflicts have demonstrated the substantial risk of spinal injury for the modern warfighter. Finite element models used to investigate injury mechanisms often fail to examine the effects of variation in geometry or material properties on mechanical behavior. The goals of this study were to model geometric variation for a set of cervical spines, to extend this model to a parametric finite element model, and, as a first step, to validate the parametric model against experimental data for low-loading conditions. Individual finite element models were created using cervical spine (C3-T1 CT data for five male cadavers. Statistical shape modeling was used to generate a parametric finite element model incorporating variability of spine geometry, and soft tissue material property variation was also included. The probabilistic loading response of the parametric model was determined under flexion-extension, axial rotation, and lateral bending and validated by comparison to experimental data. Based on qualitative and quantitative comparison of the experimental loading response and model simulations, we suggest that the model performs adequately under relatively low-level loading conditions in multiple loading directions. In conclusion, statistical shape modeling methods coupled with finite element analyses within a probabilistic framework, along with the ability to statistically validate the overall model performance, provide innovative and important steps towards describing the differences in vertebral morphology, spinal curvature, and variation in material properties. We suggest that these methods, with additional investigation and validation under injurious loading conditions, will lead to understanding and mitigating the risks of injury in the spine and other musculoskeletal structures.
Robnik, M; Prosen, T; Robnik, Marko; Dobnikar, Jure; Prosen, Tomaz
1999-01-01
Energy spectra of a particle with mass $m$ and charge $e$ in the cubic Aharonov-Bohm billiard containing around $10^4$ consecutive levels starting from the ground state have been analysed. The cubic Aharonov-Bohm billiard is a plane billiard defined by the cubic conformal mapping of the unit disc pervaded by a point magnetic flux through the origin perpendicular to the plane of the billiard. The magnetic flux does not influence the classical dynamics, but breaks the antiunitary symmetry in the system, which affects the statistics of energy levels. By varying the shape parameter $\\lam$ the classical dynamics goes from integrable ($\\lam =0$) to fully chaotic ($\\lam = 0.2$; Africa billiard). The level spacing distribution $P(S)$ and the number variance interval ($0\\le\\lam\\le0.2$). GUE statistics has proven correct for completely chaotic case, while in the mixed regime the fractional power law level repulsion has been observed. The exponent of the level repulsion has been analysed and is found to change smoothly ...
Directory of Open Access Journals (Sweden)
Nawrocki P.
2016-12-01
Full Text Available The article presents a statistical analysis of data collected from the observation of the production of austempered ductile iron. The impact assessment of the chemical composition, i.e. high contents of Cu and Ni on the properties of ductile iron isothermal tempered is critical to find the right chemical composition of austempered ductile iron. Based on the analyses range of the percentage of Cu and Ni which were selected in the cast iron to obtain material with high strength properties.
Statistical alignment: computational properties, homology testing and goodness-of-fit
DEFF Research Database (Denmark)
Hein, J; Wiuf, Carsten; Møller, Martin
2000-01-01
The model of insertions and deletions in biological sequences, first formulated by Thorne, Kishino, and Felsenstein in 1991 (the TKF91 model), provides a basis for performing alignment within a statistical framework. Here we investigate this model.Firstly, we show how to accelerate the statistical...... likelihood estimate. In addition, the recursions originally presented by Thorne, Kishino and Felsenstein can be simplified. Two proteins, about 1500 amino acids long, can be analysed with this method in less than five seconds on a fast desktop computer, which makes this method practical for actual data...... analysis.Secondly, we propose a new homology test based on this model, where homology means that an ancestor to a sequence pair can be found finitely far back in time. This test has statistical advantages relative to the traditional shuffle test for proteins.Finally, we describe a goodness-of-fit test...
Spatial accessibility and availability measures and statistical properties in the food environment.
Van Meter, E; Lawson, A B; Colabianchi, N; Nichols, M; Hibbert, J; Porter, D; Liese, A D
2011-03-01
Spatial accessibility is of increasing interest in the health sciences. This paper addresses the statistical use of spatial accessibility and availability indices. These measures are evaluated via an extensive simulation based on cluster models for local food outlet density. We derived Monte Carlo critical values for several statistical tests based on the indices. In particular we are interested in the ability to make inferential comparisons between different study areas where indices of accessibility and availability are to be calculated. We derive tests of mean difference as well as tests for differences in Moran's I for spatial correlation for each of the accessibility and availability indices. We also apply these new statistical tests to a data example based on two counties in South Carolina for various accessibility and availability measures calculated for food outlets, stores, and restaurants.
Sound Source Distance Estimation in Rooms based on Statistical Properties of Binaural Signals
DEFF Research Database (Denmark)
Georganti, Eleftheria; May, Tobias; van de Par, Steven
2013-01-01
A novel method for the estimation of the distance of a sound source from binaural speech signals is proposed. The method relies on several statistical features extracted from such signals and their binaural cues. Firstly, the standard deviation of the difference of the magnitude spectra of the left...... and right binaural signals is used as a feature for this method. In addition, an extended set of additional statistical features that can improve distance detection is extracted from an auditory front-end which models the peripheral processing of the human auditory system. The method incorporates the above...
Institute of Scientific and Technical Information of China (English)
曹勇; 吴义强
2008-01-01
Green composites made from bamboo fibers and biodegradable resins were fabricated with press molding.On the basis of the Weibull distribution and the weakest-link theory,the statistical strength and distribution of bamboo fiber were analyzed,and the tensile strength of green composites was also investigated.The result confirms that the tensile statistical strength of fiber fits well with two-parameter Weibull distribution.In addition,the tensile strength of bamboo fiber reinforced composites is about 330 MPa with the fiber volume fraction of 70%.This value is close to or higher than that of other natural fiber reinforced green composites.
Hong, Sun Suk; Lee, Jong-Woong; Seo, Jeong Beom; Jung, Jae-Eun; Choi, Jiwon; Kweon, Dae Cheol
2013-12-01
The purpose of this research is to determine the adaptive statistical iterative reconstruction (ASIR) level that enables optimal image quality and dose reduction in the chest computed tomography (CT) protocol with ASIR. A chest phantom with 0-50 % ASIR levels was scanned and then noise power spectrum (NPS), signal and noise and the degree of distortion of peak signal-to-noise ratio (PSNR) and the root-mean-square error (RMSE) were measured. In addition, the objectivity of the experiment was measured using the American College of Radiology (ACR) phantom. Moreover, on a qualitative basis, five lesions' resolution, latitude and distortion degree of chest phantom and their compiled statistics were evaluated. The NPS value decreased as the frequency increased. The lowest noise and deviation were at the 20 % ASIR level, mean 126.15 ± 22.21. As a result of the degree of distortion, signal-to-noise ratio and PSNR at 20 % ASIR level were at the highest value as 31.0 and 41.52. However, maximum absolute error and RMSE showed the lowest deviation value as 11.2 and 16. In the ACR phantom study, all ASIR levels were within acceptable allowance of guidelines. The 20 % ASIR level performed best in qualitative evaluation at five lesions of chest phantom as resolution score 4.3, latitude 3.47 and the degree of distortion 4.25. The 20 % ASIR level was proved to be the best in all experiments, noise, distortion evaluation using ImageJ and qualitative evaluation of five lesions of a chest phantom. Therefore, optimal images as well as reduce radiation dose would be acquired when 20 % ASIR level in thoracic CT is applied.
Schneidmiller, E A
2015-01-01
We describe statistical and coherence properties of the radiation from x-ray free electron lasers (XFEL) operating in the post-saturation regime. We consider practical case of the SASE3 FEL at the European XFEL. We perform comparison of the main characteristics of the X-ray FEL operating in the post-saturation regime with and without undulator tapering: efficiency, coherence time and degree of transverse coherence.
Setting the normalcy level of HI properties in isolated galaxies
Espada, D; Athanassoula, E; Bosma, A; Huchtmeier, W K; Leon, S; Lisenfeld, U; Sabater, J; Sulentic, J; Verley, S; Yun, M
2009-01-01
Studying the atomic gas (HI) properties of the most isolated galaxies is essential to quantify the effect that the environment exerts on this sensitive component of the interstellar medium. We observed and compiled HI data for a well defined sample of ~ 800 galaxies in the Catalog of Isolated Galaxies, as part of the AMIGA project (Analysis of the ISM in Isolated GAlaxies, http://amiga.iaa.es), which enlarges considerably previous samples used to quantify the HI deficiency in galaxies located in denser environments. By studying the shape of 182 HI profiles, we revisited the usually accepted result that, independently of the environment, more than half of the galaxies present a perturbed HI disk. In isolated galaxies this would certainly be a striking result if these are supposed to be the most relaxed systems, and has implications in the relaxation time scales of HI disks and the nature of the most frequent perturbing mechanisms in galaxies. Our sample likely exhibits the lowest HI asymmetry level in the loca...
Statistical analysis for precise estimation of structural properties of NGC 1960
Joshi, Gireesh C
2016-01-01
The statistical analysis of gathered of astronomical objects (such as open cluster) are excellent tools to compute its parameters and to constrain the theory of its evolution. Here, we are represented detailed structural and membership analysis of an open cluster NGC 1960 through various statistical formulas and approaches. King empirical methods provide the information about the cluster extent as 5.2 +/- 0.4 pc. The exact identification of members of cluster is needed to precise estimation of its age, reddening, metallicity etc., therefore, to identify most probable members (MPMs), we adopted the combined approach of various statistical methods (kinematic, photometric and statistical) and 712 members are satisfied needed criteria of MPMs. The basic physical parameters of the cluster such as E(B-V)=0.23+/-0.02 mag, E(V-K)=1.05+/-0.03mag, log(Age)=7.35+/-0.05, and (m-M)=11.35+/-0.10 mag are obtained using the color-color and color-magnitude diagrams. NGC 1960 is found to be located at a distance of 1.34 +/- 0....
Basic properties and information theory of Audic-Claverie statistic for analyzing cDNA arrays
Tiňo, Peter
2009-01-01
Background The Audic-Claverie method [1] has been and still continues to be a popular approach for detection of differentially expressed genes in the SAGE framework. The method is based on the assumption that under the null hypothesis tag counts of the same gene in two libraries come from the same but unknown Poisson distribution. The problem is that each SAGE library represents only a single measurement. We ask: Given that the tag count samples from SAGE libraries are extremely limited, how useful actually is the Audic-Claverie methodology? We rigorously analyze the A-C statistic that forms a backbone of the methodology and represents our knowledge of the underlying tag generating process based on one observation. Results We show that the A-C statistic and the underlying Poisson distribution of the tag counts share the same mode structure. Moreover, the K-L divergence from the true unknown Poisson distribution to the A-C statistic is minimized when the A-C statistic is conditioned on the mode of the Poisson distribution. Most importantly, the expectation of this K-L divergence never exceeds 1/2 bit. Conclusion A rigorous underpinning of the Audic-Claverie methodology has been missing. Our results constitute a rigorous argument supporting the use of Audic-Claverie method even though the SAGE libraries represent very sparse samples. PMID:19775462
Grima, C.; Rosales, A.; Blankenship, D. D.; Young, D. A.
2014-12-01
McMurdo Ice Shelf, Antarctica, is characterized by two particular geophysical processes. (1) Marine ice accretion supplies most of the ice shelf material rather than meteoric ice from glacier outflow and snow-falls. (2) A brine layer infiltrates the ice shelf laterally up to 20-km inward. The infiltration mainly initiates at the ice-front from sea water percolation when the firn/snow transition is below sea-level. A better characterization of the McMurdo ice shelf could constrain our knowledges of these mechanisms and assess the stability of the region that hosts numerous human activities from the close McMurdo station (USA) and Scott base (New-Zealand). McMurdo ice shelf is also an analog for the Jovian icy moon Europa where brine pockets are supposed to reside in the ice crust and accretion to occur at the 10-30-km deep ice-ocean interface.The University of Texas Institute for Geophysics (UTIG) acquired two radar survey grids over the McMurdo Ice Shelf during southern summers 2011-2012 and 2012-2013 with the High Capability Radar Sounder (HiCARS) on-board a Basler DC-3 aircraft. HiCARS transmits a chirped signal at 60-MHz central frequency and 15-MHz bandwidth. The corresponding vertical resolution in ice is 5-10 m. An important design goal of the radar was to maintain sufficient dynamic range to correctly measure echo intensities.Here we present the brine infiltration extent and bathymetry derived from its dielectric horizon well distinguishable on the HiCARS radargram. We complement the ice-shelf characterization by classifying its surface thanks to the novel Radar Statistical Reconnaissance (RSR) methodology. The RSR observable is the statistical distribution of the surface echo amplitudes from successive areas defined along-track. The distributions are best-fitted with a theoretical stochastic envelop parameterized with the signal reflectance and scattering. Once those two components are deduced from the fit, they are used in a backscattering model to invert
Gomez, W; Pereira, W C A; Infantosi, A F C
2012-10-01
In this paper, we investigated the behavior of 22 co-occurrence statistics combined to six gray-scale quantization levels to classify breast lesions on ultrasound (BUS) images. The database of 436 BUS images used in this investigation was formed by 217 carcinoma and 219 benign lesions images. The region delimited by a minimum bounding rectangle around the lesion was employed to calculate the gray-level co-occurrence matrix (GLCM). Next, 22 co-occurrence statistics were computed regarding six quantization levels (8, 16, 32, 64, 128, and 256), four orientations (0° , 45° , 90° , and 135°), and ten distances (1, 2,...,10 pixels). Also, to reduce feature space dimensionality, texture descriptors of the same distance were averaged over all orientations, which is a common practice in the literature. Thereafter, the feature space was ranked using mutual information technique with minimal-redundancy-maximal-relevance (mRMR) criterion. Fisher linear discriminant analysis (FLDA) was applied to assess the discrimination power of texture features, by adding the first m-ranked features to the classification procedure iteratively until all of them were considered. The area under ROC curve (AUC) was used as figure of merit to measure the performance of the classifier. It was observed that averaging texture descriptors of a same distance impacts negatively the classification performance, since the best AUC of 0.81 was achieved with 32 gray levels and 109 features. On the other hand, regarding the single texture features (i.e., without averaging procedure), the quantization level does not impact the discrimination power, since AUC = 0.87 was obtained for the six quantization levels. Moreover, the number of features was reduced (between 17 and 24 features). The texture descriptors that contributed notably to distinguish breast lesions were contrast and correlation computed from GLCMs with orientation of 90° and distance more than five pixels.
Guilhon, I.; Bechstedt, F.; Botti, Silvana; Marques, M.; Teles, L. K.
2017-06-01
We study the incomplete oxidation of graphene or reduction of graphene oxide for hydroxyl and epoxy oxidant groups. While in wet oxidation hydroxyl groups are favorable, in a drier environment an oxygen atom can bridge two neighboring carbon atoms. We model composition variations and structural disorder within a statistical theory, the generalized quasichemical approximation, combined with density functional theory calculations of the local atomic geometries. A generalization of the statistical approach is developed to account for the antiparallel orientation of hydroxyl groups and a fourfold coordination of C atoms. The theoretical framework enables a thermodynamic treatment of graphene oxide as a function of oxygen content, allowing us to derive temperature-composition phase diagrams and investigate possible clustering and segregation. The resulting geometries, local and average electronic structures, and optical absorption spectra are discussed and compared with available experimental data.
Hara, T.; Seki, K.; Futaana, Y.; Yamauchi, M.; Barabash, S.; Fedorov, A. O.; Yagi, M.; Delcourt, D. C.
2013-09-01
Picked-up ion precipitations are a potential mechanism to increase an atmospheric escape from the unmagnetized planet of Mars. The interplanetary magnetic field (IMF) embedded in the supersonic solar wind is one of the crucial parameters to control the behavior of the Martian planetary heavy ions. We statistically investigated the effects of the IMF orientation on planetary heavy ions precipitating toward the Martian ionosphere by using data obtained from the Ion Mass Analyzer (IMA) onboard the Mars Express (MEX). To compensate for the absence of a magnetometer onboard MEX, we estimated the IMF orientation from the velocity distribution function of exospheric protons observed in the solar wind. The statistical analysis shows that the precipitations of planetary heavy ions tend to be observed in the direction or the anti-parallel direction of the solar wind electric field inferred from the estimated IMF orientation. We defined the IMF polarity for one event via comparisons of the ion velocity distribution function obtained from MEX/IMA observations and a statistical trajectory tracing of test particles. The estimated polarity corresponds to the anti-parallel direction to the solar wind electric field and is consistent with the asymmetrical distribution of planetary heavy ion precipitation in terms of the solar wind electric field derived from the previous numerical simulations. The observed precipitating planetary heavy ions are accelerated only up to a few keV. This feature may reflect the short distance from the picked-up region in the magnetosheath.
Zilany, Muhammad S A; Carney, Laurel H
2010-08-04
Neurons in the auditory system respond to recent stimulus-level history by adapting their response functions according to the statistics of the stimulus, partially alleviating the so-called "dynamic-range problem." However, the mechanism and source of this adaptation along the auditory pathway remain unknown. Inclusion of power-law dynamics in a phenomenological model of the inner hair cell (IHC)-auditory nerve (AN) synapse successfully explained neural adaptation to sound-level statistics, including the time course of adaptation of the mean firing rate and changes in the dynamic range observed in AN responses. A direct comparison between model responses to a dynamic stimulus and to an "inversely gated" static background suggested that AN dynamic-range adaptation largely results from the adaptation produced by the response history. These results support the hypothesis that the potential mechanism underlying the dynamic-range adaptation observed at the level of the auditory nerve is located peripheral to the spike generation mechanism and central to the IHC receptor potential.
Statistical study of Saturn's auroral electron properties with Cassini/UVIS FUV spectral images
Gustin, J.; Grodent, D.; Radioti, A.; Pryor, W.; Lamy, L.; Ajello, J.
2017-03-01
About 2000 FUV spectra of different regions of Saturn's aurora, obtained with Cassini/UVIS from December 2007 to October 2014 have been examined. Two methods have been employed to determine the mean energy of the precipitating electrons. The first is based on the absorption of the auroral emission by hydrocarbons and the second uses the ratio between the brightness of the Lyman-α line and the H2 total UV emission (Lyα/H2), which is directly related to via a radiative transfer formalism. In addition, two atmospheric models obtained recently from UVIS polar occultations have been employed for the first time. It is found that the atmospheric model related to North observations near 70° latitude provides the results most consistent with constraints previously published. On a global point of view, the two methods provide comparable results, with mostly in the 7-17 keV range with the hydrocarbon method and in the 1-11 keV range with the Lyα/H2 method. Since hydrocarbons have been detected on ∼20% of the auroral spectra, the Lyα/H2 technique is more effective to describe the primary auroral electrons, as it is applicable to all spectra and allows an access to the lowest range of energies (≤5 keV), unreachable by the hydrocarbon method. The distribution of is found fully compatible with independent HST/ACS constraints (emission peak in the 840-1450 km range) and FUSE findings (emission peaking at pressure level ≤0.2 μbar). In addition, exhibits enhancements in the 3 LT-10 LT sector, consistent with SKR intensity measurements. An energy flux-electron energy diagram built from all the data points strongly suggests that acceleration by field-aligned potentials as described by Knight's theory is a main mechanism responsible for electron precipitation creating the aurora. Assuming a fixed electron temperature of 0.1 keV, a best-fit equatorial electron source population density of 3 × 103 m-3 is derived, which matches very well to the plasma properties observed with
Choi, Hyungwon; Kim, Sinae; Fermin, Damian; Tsou, Chih-Chiang; Nesvizhskii, Alexey I
2015-11-03
We introduce QPROT, a statistical framework and computational tool for differential protein expression analysis using protein intensity data. QPROT is an extension of the QSPEC suite, originally developed for spectral count data, adapted for the analysis using continuously measured protein-level intensity data. QPROT offers a new intensity normalization procedure and model-based differential expression analysis, both of which account for missing data. Determination of differential expression of each protein is based on the standardized Z-statistic based on the posterior distribution of the log fold change parameter, guided by the false discovery rate estimated by a well-known Empirical Bayes method. We evaluated the classification performance of QPROT using the quantification calibration data from the clinical proteomic technology assessment for cancer (CPTAC) study and a recently published Escherichia coli benchmark dataset, with evaluation of FDR accuracy in the latter. QPROT is a statistical framework with computational software tool for comparative quantitative proteomics analysis. It features various extensions of QSPEC method originally built for spectral count data analysis, including probabilistic treatment of missing values in protein intensity data. With the increasing popularity of label-free quantitative proteomics data, the proposed method and accompanying software suite will be immediately useful for many proteomics laboratories. This article is part of a Special Issue entitled: Computational Proteomics. Copyright © 2015 Elsevier B.V. All rights reserved.
Relative level of occurrence of the principal heuristics in Nigeria property valuation
Directory of Open Access Journals (Sweden)
Iroham C.O.,
2013-06-01
Full Text Available The neglect of the other principal heuristics namely avaialability, representative and positivity in real estate behaviourial property research as against the exclusive focus on anchoring and adjustment heuristics invariably results to a lopsided research. This work studied the four principal heuristics in property behaviourial property valutaion in a bid to discovering its relative level of occurrence. The study adopted a cross-sectional questionnaire survey approach of 159 of the 270 Head Offices of Estate Surveying and Valuation firms in Lagos Metropolis, while 29 and 30 questionnaire were distributed to the Head Offices of the entire Estate Surveying and Valuation Firms in Abuja and Port-Harcourt respectively. The data gotten was analyzed with the aid of Statistical Package for the Social Sciences first using frequency distributions/means and the data so analyzed was further analyzed using maximum and minimum values, means/standard deviations and ultimately ranking of such means. The result revealed that respondents use the various principal heuristics in this decreasing order of magnitude: availability heuristics (26.77%, anchoring and adjustment heuristics (18.62%; representative heuristics (15.63% and least of all positivity heuristics (10.41%. The authors thereby opined that emphasis be placed more on availability heuristics research particularly as usage of heuristcis (anchoring and adjustment has been seen to influence valuation inconsistency/accuracy
Energy Technology Data Exchange (ETDEWEB)
Jung, Byung C. [University of Maryland, College Park (United States); Lee, Doo Ho [Dongeui University, Busan (Korea, Republic of); Youn, Byeng D. [Seoul National University, Seoul (Korea, Republic of); Lee, Soo Bum [University of Notre Dame, Notre Dame (United States)
2011-08-15
The performance of surface damping treatments may vary once the surface is exposed to a wide range of temperatures, because the performance of viscoelastic damping material is highly dependent on operational temperature. In addition, experimental data for dynamic responses of viscoelastic material are inherently random, which makes it difficult to design a robust damping layout. In this paper a statistical modeling procedure with a statistical calibration method is suggested for the variability characterization of viscoelastic damping material in constrained-layer damping structures. First, the viscoelastic material property is decomposed into two sources: (I) a random complex modulus due to operational temperature variability, and (II) experimental/model errors in the complex modulus. Next, the variability in the damping material property is obtained using the statistical calibration method by solving an unconstrained optimization problem with a likelihood function metric. Two case studies are considered to show the influence of the material variability on the acoustic performances in the structural-acoustic systems. It is shown that the variability of the damping material is propagated to that of the acoustic performances in the systems. Finally, robust and reliable damping layout designs of the two case studies are obtained through the reliability-based design optimization (RBDO) amidst severe variability in operational temperature and the damping material.
Orlowski, D. S.; Le, G.; Russell, C. T.; Krauss-Varban, D.; Omidi, N.
1995-01-01
In this report we present a different approach to the multipoint measurement of magnetic fields and plasma. This is called the multi-spacecraft ensemble technique (MET), essentially free of process restrictions, such as linearity and stationarity. We comprehensively discuss the other conditions and limitations intrinsic to this statistical method. We also show the results of the application of the ensemble method to the synthetic data obtained from a hybrid simulation in the region upstream of a quasi-parallel shock. The important implications of the above approach for the CLUSTER mission are discussed.
Spatial Statistics and Spatio-Temporal Data Covariance Functions and Directional Properties
Sherman, Michael
2010-01-01
In the spatial or space-time context, specifying the correct covariance function is important to obtain efficient predictions and to understand the underlying physical process of interest. There have been several books in recent years in the general area of spatial statistics. This book focuses on covariance and variogram functions, their role in prediction, and the proper choice of these functions in data applications. Presenting recent methods from 2004-2007 alongside more established methodology of assessing the usual assumptions on such functions such as isotropy, separability and symmetry
Statistical properties of first-order bang-bang Pll with nonzero loop delay
Chun, Byungjin; Kennedy, Michael Peter
2008-01-01
A method to solve the stationary state probability is presented for the first-order bang-bang phase-locked loop (BBPLL) with nonzero loop delay. This is based on a delayed Markov chain model and a state How diagram for tracing the state history due to the loop delay. As a result, an eigenequation is obtained, and its closed form solutions are derived for some cases. After obtaining the state probability, statistical characteristics such as mean gain of the binary phase detector and timing err...
Energy Technology Data Exchange (ETDEWEB)
Yoshimoto, H. [Ship Research Inst., Tokyo (Japan)
1996-12-31
Since ocean waves encountered by ocean vessels or offshore structures in actual sea areas present extremely irregular variations, a stochastic method is necessary to estimate their statistical properties. This paper first shows a calculation method for probability density function for water level variation which strictly incorporates a secondary non-linear effect containing directional dispersibility by modeling ocean waves as short-crested irregular waves. Then, the paper specifically elucidates effects of the directional dispersibility of ocean waves on statistical amount of amplitudes by deriving the statistical amount of the amplitudes based on the probability density function of the water level variation and by using a numerical simulation. The paper finally takes up data of waves in stormy sea observed in an experiment in an actual sea area, compares the result with that of theoretical calculations, and evaluates reasonability of this method. With this estimation method, individual secondary components or components of difference and sum may be subjected to influence of the directional dispersibility, but they do not differ much from the case of long-crested irregular waves on the whole. 21 refs., 11 figs., 2 tabs.
Eliazar, Iddo
2017-05-01
The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their 'public relations' for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford's law, and 1/f noise.
Multi-wavelength studies of the statistical properties of active galaxies using Big Data
Mickaelian, A. M.; Abrahamyan, H. V.; Gyulzadyan, M. V.; Mikayelyan, G. A.; Paronyan, G. M.
2017-06-01
Statistical studies of active galaxies (both AGN and Starburst) using large multi-wavelength data are presented, including new studies of Markarian galaxies, large sample of IR galaxies, variable radio sources, and large homogeneous sample of X-ray selected AGN. Markarian survey (the First Byurakan Survey) was digitized and the DFBS database was created, as the biggest spectroscopic database by the number of objects involved ( ~ 20 million). This database provides both 2D images and 1D spectra. We have carried out a number of projects aimed at revealing and multi-wavelength studies of active galaxies among optical, X-ray, IR and radio sources. Thousands of X-ray sources were identified from ROSAT, including many AGN (52% among all identified sources). IRAS PSC/FSC sources were studied having accurate positions from WISE and a large extragalactic sample was created for further search for AGNs. The fraction of active galaxies among IR-selected galaxies was estimated as 24%. Variable radio sources at 1.4 GHz were revealed by cross-correlation of NVSS and FIRST catalogues using the method introduced by us for optical variability. Radio-X-ray sources were revealed from NVSS and ROSAT for detection of new active galaxies. Big Data in astronomy is described that provide new possibilities for statistical research of active galaxies and other objects.
de Savigny, Don; Riley, Ian; Chandramohan, Daniel; Odhiambo, Frank; Nichols, Erin; Notzon, Sam; AbouZahr, Carla; Mitra, Raj; Cobos Muñoz, Daniel; Firth, Sonja; Maire, Nicolas; Sankoh, Osman; Bronson, Gay; Setel, Philip; Byass, Peter; Jakob, Robert; Boerma, Ties; Lopez, Alan D.
2017-01-01
ABSTRACT Background: Reliable and representative cause of death (COD) statistics are essential to inform public health policy, respond to emerging health needs, and document progress towards Sustainable Development Goals. However, less than one-third of deaths worldwide are assigned a cause. Civil registration and vital statistics (CRVS) systems in low- and lower-middle-income countries are failing to provide timely, complete and accurate vital statistics, and it will still be some time before they can provide physician-certified COD for every death. Proposals: Verbal autopsy (VA) is a method to ascertain the probable COD and, although imperfect, it is the best alternative in the absence of medical certification. There is extensive experience with VA in research settings but only a few examples of its use on a large scale. Data collection using electronic questionnaires on mobile devices and computer algorithms to analyse responses and estimate probable COD have increased the potential for VA to be routinely applied in CRVS systems. However, a number of CRVS and health system integration issues should be considered in planning, piloting and implementing a system-wide intervention such as VA. These include addressing the multiplicity of stakeholders and sub-systems involved, integration with existing CRVS work processes and information flows, linking VA results to civil registration records, information technology requirements and data quality assurance. Conclusions: Integrating VA within CRVS systems is not simply a technical undertaking. It will have profound system-wide effects that should be carefully considered when planning for an effective implementation. This paper identifies and discusses the major system-level issues and emerging practices, provides a planning checklist of system-level considerations and proposes an overview for how VA can be integrated into routine CRVS systems. PMID:28137194
β-Amyloid pathogenesis: Chemical properties versus cellular levels
DEFF Research Database (Denmark)
Tiwari, Manish Kumar; Kepp, Kasper Planeta
2016-01-01
, or aggregation propensities. Cytotoxicity correlates inversely with total Aβ42 (R2=0.65, P =.016) and Aβ42/Aβ40 ratios (R2=0.76, P=.005), i.e., chemical properties that increase Aβ42 also reduce toxicity. The complexity and heterogeneity of data reveal the need to understand these phenotypes better, e.......g., by focusing on the chemical properties of the involved Aβ species....
Inverse limits and statistical properties for chaotic implicitly defined economic models
Mihailescu, Eugen
2011-01-01
In this paper we study the dynamics and ergodic theory of certain economic models which are implicitly defined. We consider 1-dimensional and 2-dimensional overlapping generations models, a cash-in-advance model, heterogeneous markets and a cobweb model with adaptive adjustment. We consider the inverse limit spaces of certain chaotic invariant fractal sets and their metric, ergodic and stability properties. The inverse limits give the set of intertemporal perfect foresight equilibria for the economic problem considered. First we show that the inverse limits of these models are stable under perturbations. We prove that the inverse limits are expansive and have specification property. We then employ utility functions on inverse limits in our case. We give two ways to rank such utility functions. First, when perturbing certain dynamical systems, we rank utility functions in terms of their \\textit{average values} with respect to invariant probability measures on inverse limits, especially with respect to measures...
On the statistical and transport properties of a non-dissipative Fermi-Ulam model
Energy Technology Data Exchange (ETDEWEB)
Livorati, André L. P. [Departamento de Física, UNESP - Univ. Estadual Paulista, Ave. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Instituto de Física, IFUSP - Universidade de São Paulo, Rua do Matão, Tr.R 187, Cidade Universitária, 05314-970 São Paulo, SP (Brazil); School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Dettmann, Carl P. [School of Mathematics, University of Bristol, Bristol BS8 1TW (United Kingdom); Caldas, Iberê L. [Instituto de Física, IFUSP - Universidade de São Paulo, Rua do Matão, Tr.R 187, Cidade Universitária, 05314-970 São Paulo, SP (Brazil); Leonel, Edson D. [Departamento de Física, UNESP - Univ. Estadual Paulista, Ave. 24A, 1515, Bela Vista, 13506-900 Rio Claro, SP (Brazil); Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34151 Trieste (Italy)
2015-10-15
The transport and diffusion properties for the velocity of a Fermi-Ulam model were characterized using the decay rate of the survival probability. The system consists of an ensemble of non-interacting particles confined to move along and experience elastic collisions with two infinitely heavy walls. One is fixed, working as a returning mechanism of the colliding particles, while the other one moves periodically in time. The diffusion equation is solved, and the diffusion coefficient is numerically estimated by means of the averaged square velocity. Our results show remarkably good agreement of the theory and simulation for the chaotic sea below the first elliptic island in the phase space. From the decay rates of the survival probability, we obtained transport properties that can be extended to other nonlinear mappings, as well to billiard problems.
Indian Academy of Sciences (India)
R. Cassano; G. Brunetti; T. Venturi
2011-12-01
We discuss the statistical properties of the radio halo population in galaxy clusters. Radio bi-modality is observed in galaxy clusters: a fraction of clusters host giant radio halos while a majority of clusters do not show evidence of diffuse cluster-scale radio emission. The radio bi-modality has a correspondence in terms of dynamical state of the hosting clusters showing that merging clusters host radio halos and follow the well-known radio-X-ray correlation, while more relaxed clusters do not host radio halos and populate a region well separated from that correlation. These evidences can be understood in the framework of a scenario wheremerger-driven turbulence re-accelerate the radio emitting electrons. We discuss the main statistical expectations of this scenario underlining the important role of the upcoming LOFAR surveys to test present models.
Statistical properties of 243Pu, and 242Pu(n ,γ ) cross section calculation
Laplace, T. A.; Zeiser, F.; Guttormsen, M.; Larsen, A. C.; Bleuel, D. L.; Bernstein, L. A.; Goldblum, B. L.; Siem, S.; Garotte, F. L. Bello; Brown, J. A.; Campo, L. Crespo; Eriksen, T. K.; Giacoppo, F.; Görgen, A.; Hadyńska-KlÈ©k, K.; Henderson, R. A.; Klintefjord, M.; Lebois, M.; Renstrøm, T.; Rose, S. J.; Sahin, E.; Tornyi, T. G.; Tveten, G. M.; Voinov, A.; Wiedeking, M.; Wilson, J. N.; Younes, W.
2016-01-01
The level density and γ -ray strength function (γ SF ) of 243Pu have been measured in the quasicontinuum using the Oslo method. Excited states in 243Pu were populated using the 242Pu(d ,p ) reaction. The level density closely follows the constant-temperature level density formula for excitation energies above the pairing gap. The γ SF displays a double-humped resonance at low energy as also seen in previous investigations of actinide isotopes. The structure is interpreted as the scissors resonance and has a centroid of ωSR=2.42 (5 ) MeV and a total strength of BSR=10.1 (15 ) μN2 , which is in excellent agreement with sum-rule estimates. The measured level density and γ SF were used to calculate the 242Pu(n ,γ ) cross section in a neutron energy range for which there were previously no measured data.
41 CFR 109-42.1102-52 - Low level contaminated personal property.
2010-07-01
... for shipment as provided in Department of Transportation Regulations (49 CFR parts 171-179) for... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Low level contaminated... level contaminated personal property. If monitoring of suspect personal property indicates...
Directory of Open Access Journals (Sweden)
Baddari Kamel
2016-10-01
Full Text Available Statistical tests have been used to adjust the Zemmouri seismic data using a distribution function. The Pareto law has been used and the probabilities of various expected earthquakes were computed. A mathematical expression giving the quantiles was established. The extreme values limiting law confirmed the accuracy of the adjustment method. Using the moment magnitude scale, a probabilistic model was made to predict the occurrences of strong earthquakes. The seismic structure has been characterized by the slope of the recurrence plot γ, fractal dimension D, concentration parameter Ksr, Hurst exponents Hr and Ht. The values of D, γ, Ksr, Hr, and Ht diminished many months before the principal seismic shock (M = 6.9 of the studied seismoactive zone has occurred. Three stages of the deformation of the geophysical medium are manifested in the variation of the coefficient G% of the clustering of minor seismic events.
Baddari, Kamel; Bellalem, Fouzi; Baddari, Ibtihel; Makdeche, Said
2016-10-01
Statistical tests have been used to adjust the Zemmouri seismic data using a distribution function. The Pareto law has been used and the probabilities of various expected earthquakes were computed. A mathematical expression giving the quantiles was established. The extreme values limiting law confirmed the accuracy of the adjustment method. Using the moment magnitude scale, a probabilistic model was made to predict the occurrences of strong earthquakes. The seismic structure has been characterized by the slope of the recurrence plot γ, fractal dimension D, concentration parameter K sr, Hurst exponents H r and H t. The values of D, γ, K sr, H r, and H t diminished many months before the principal seismic shock ( M = 6.9) of the studied seismoactive zone has occurred. Three stages of the deformation of the geophysical medium are manifested in the variation of the coefficient G% of the clustering of minor seismic events.
Statistical properties of kinetic and total energy densities in reverberant spaces
DEFF Research Database (Denmark)
Jacobsen, Finn; Molares, Alfonso Rodriguez
2010-01-01
. With the advent of a three-dimensional particle velocity transducer, it has become somewhat easier to measure total rather than only potential energy density in a sound field. This paper examines the ensemble statistics of kinetic and total sound energy densities in reverberant enclosures theoretically......Many acoustical measurements, e.g., measurement of sound power and transmission loss, rely on determining the total sound energy in a reverberation room. The total energy is usually approximated by measuring the mean-square pressure (i.e., the potential energy density) at a number of discrete...... positions. The idea of measuring the total energy density instead of the potential energy density on the assumption that the former quantity varies less with position than the latter goes back to the 1930s. However, the phenomenon was not analyzed until the late 1970s and then only for the region of high...
Statistical Properties of Photon-Added Two-Mode Squeezed Coherent States
Wang, Zhen; Li, Heng-Mei; Yuan, Hong-Chun; Wan, Zhi-Long; Meng, Xiang-Guo
2016-12-01
The nonclassical and non-Gaussian quantum states—photon-added two-mode squeezed coherent states have been theoretically introduced by adding multiple photons to each mode of the two-mode squeezed coherent states. Starting from the new expression of two-mode squeezing operator in entangled states representation, the normalization factor is obtained, which is directly related to bivariate Hermite polynomials. The sub-Poissonian photon statistics, cross-correlation between two modes, partial negative Wigner function are observed, which fully reflect the nonclassicality of the target states. The negative Wigner function often display non-Gaussian distribution meanwhile. The investigations may provide experimentalists with some better references in quantum engineering.
A granocentric model captures the statistical properties of monodisperse random packings
Newhall, Katherine A; Vanden-Eijnden, Eric; Brujic, Jasna
2012-01-01
We present a generalization of the granocentric model proposed in [Clusel et al., Nature, 2009, 460, 611615] that is capable of describing the local fluctuations inside not only polydisperse but also monodisperse packings of spheres. This minimal model does not take into account the relative particle positions, yet it captures positional disorder through local stochastic processes sampled by efficient Monte Carlo methods. The disorder is characterized by the distributions of local parameters, such as the number of neighbors and contacts, filled solid angle around a central particle and the cell volumes. The model predictions are in good agreement with our experimental data on monodisperse random close packings of PMMA particles. Moreover, the model can be used to predict the distributions of local fluctuations in any packing, as long as the average number of neighbors, contacts and the packing fraction are known. These distributions give a microscopic foundation to the statistical mechanics framework for jamm...
Statistical properties of photon modes in random arrays of ZnO nano-needles
Energy Technology Data Exchange (ETDEWEB)
Minz, Christoph; Leipold, David; Runge, Erich [Technische Universitaet Ilmenau, 98693 Ilmenau (Germany)
2011-07-01
Localization of electromagnetic waves in random media received renewed interest in the last years. Recent ultrafast optical experiments indicate the existence of highly localized photon modes in a system of homogeneous, randomly distributed, vertically aligned ZnO nano-needles. In particular, hot spots in the spatial distribution of the second harmonic generation (SHG) were found. In this work, we discuss the optical near field, which we obtain from full 3D solutions of Maxwell's equations of a model system in time domain. The spatial distribution of the electric near-field and the squared electric near-field intensity are investigated with statistical methods. The results are compared to the experimental findings. We thank Manfred Maschek, Slawa Schmidt, Martin Silies and Christoph Lienau from the Carl von Ossietzky Universitaet Oldenburg as well as Takashi Yatsui, Kokoro Kitamura and Motoichi Ohtsu from the University of Tokyo for sharing their experimental data with us prior to publication.
Energy Technology Data Exchange (ETDEWEB)
Smith, D.L.; Sagalovsky, L.; Micklich, B.J.; Harper, M.K.; Novick, A.H.
1994-06-01
A least-squares algorithm developed for analysis of fast-neutron transmission data resulting from non-destructive interrogation of sealed luggage and containers is subjected to a probabilistic interpretation. The approach is to convert knowledge of uncertainties in the derived areal elemental densities, as provided by this algorithm, into probability information that can be used to judge whether an interrogated object is either benign or potentially contains an illicit substance that should be investigated further. Two approaches are considered in this paper. One involves integration of a normalized probability density function associated with the least-squares solution. The other tests this solution against a hypothesis that the interrogated object indeed contains illicit material. This is accomplished by an application of the F-distribution from statistics. These two methods of data interpretation are applied to specific sets of neutron transmission results produced by Monte Carlo simulation.
Directory of Open Access Journals (Sweden)
Gregory Beskin
2014-08-01
Full Text Available The results of a study of 43 peaked R-band light curves of optical counterparts of gamma-ray bursts with known redshifts are presented. The parameters of optical transients were calculated in the comoving frame, and then a search for pair correlations between them was conducted. A statistical analysis showed a strong correlation between the peak luminosity and the redshift both for pure afterglows and for events with residual gamma activity, which cannot be explained as an effect of observational selection.This suggests a cosmological evolution of the parameters of the local interstellar medium around the sources of the gamma-ray burst. In the models of forward and reverse shock waves, a relation between the density of the interstellar medium and the redshift was built for gamma-ray burst afterglows, leading to a power-law dependence of the star-formation rate at regions around GRBs on redshift with a slope of about 6.
Goodman, Joseph W
2015-01-01
This book discusses statistical methods that are useful for treating problems in modern optics, and the application of these methods to solving a variety of such problems This book covers a variety of statistical problems in optics, including both theory and applications. The text covers the necessary background in statistics, statistical properties of light waves of various types, the theory of partial coherence and its applications, imaging with partially coherent light, atmospheric degradations of images, and noise limitations in the detection of light. New topics have been introduced i
Murugan, Karmani; Choonara, Yahya E; Kumar, Pradeep; du Toit, Lisa C; Pillay, Viness
2017-09-01
This study aimed to highlight a statistic design to precisely engineer homogenous geometric copper nanoparticles (CuNPs) for enhanced intracellular drug delivery as a function of geometrical structure. CuNPs with a dual functionality comprising geometric attributes for enhanced cell uptake and exerting cytotoxic activity on proliferating cells were synthesized as a novel drug delivery system. This paper investigated the defined concentrations of two key surfactants used in the reaction to mutually control and manipulate nano-shape and optimisation of the geometric nanosystems. A statistical experimental design comprising a full factorial model served as a refining factor to achieve homogenous geometric nanoparticles using a one-pot method for the systematic optimisation of the geometric CuNPs. Shapes of the nanoparticles were investigated to determine the result of the surfactant variation as the aim of the study and zeta potential was studied to ensure the stability of the system and establish a nanosystem of low aggregation potential. After optimisation of the nano-shapes, extensive cellular internalisation studies were conducted to elucidate the effect of geometric CuNPs on uptake rates, in addition to the vital toxicity assays to further understand the cellular effect of geometric CuNPs as a drug delivery system. In addition to geometry; volume, surface area, orientation to the cell membrane and colloidal stability is also addressed. The outcomes of the study demonstrated the success of homogenous geometric NP formation, in addition to a stable surface charge. The findings of the study can be utilized for the development of a drug delivery system for promoted cellular internalisation and effective drug delivery. Copyright © 2017 Elsevier B.V. All rights reserved.
Hara, Takuya; Seki, Kanako; Futaana, Yoshifumi; Yamauchi, Masatoshi; Barabash, Stas; Fedorov, Andrei O.; Yagi, Manabu; Delcourt, Dominique C.
2013-08-01
The interplanetary magnetic field (IMF) embedded in the solar wind interacts with the Martian crustal magnetic field and atmosphere. The IMF orientation is one of the important parameters to control the acceleration and precipitation of planetary heavy ions (PHIs). We statistically investigate the effects of the IMF orientation on PHI precipitations toward the ionosphere based on observations by Mars Express (MEX). We identified 59 PHI precipitation events between July 2007 and September 2009. To estimate the IMF orientation without magnetometer that MEX does not carry, we used the velocity distribution of exospheric-origin pickup protons. We estimated the IMF orientation without its polarity for 10 events. The results show that the precipitations of PHIs tend to be observed around pole regions in the MSE (Mars-centered, solar electrical) coordinates determined from the solar wind electric field (Esw), in which the pole axis directs to the parallel or antiparallel to Esw due to the ambiguity in the IMF polarity determination. The observed precipitating PHIs are accelerated only up to a few keV. This feature may reflect the short distance from the picked-up region. For one of these 10 events, we estimated the IMF polarity by comparing the velocity distribution of exospheric-origin pickup protons observed by MEX with those obtained from statistical trajectory tracing simulations under two cases of possible IMF polarity conditions. The estimated polarity indicates that the PHI precipitation in this event is observed in the downward electric field hemisphere in MSE, where Esw points to Mars in the pole region.
Directory of Open Access Journals (Sweden)
Said Nawar
2015-01-01
Full Text Available Modeling and mapping of soil properties has been identified as key for effective land degradation management and mitigation. The ability to model and map soil properties at sufficient accuracy for a large agriculture area is demonstrated using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER imagery. Soil samples were collected in the El-Tina Plain, Sinai, Egypt, concurrently with the acquisition of ASTER imagery, and measured for soil electrical conductivity (ECe, clay content and soil organic matter (OM. An ASTER image covering the study area was preprocessed, and two predictive models, multivariate adaptive regression splines (MARS and the partial least squares regression (PLSR, were constructed based on the ASTER spectra. For all three soil properties, the results of MARS models were better than those of the respective PLSR models, with cross-validation estimated R2 of 0.85 and 0.80 for ECe, 0.94 and 0.90 for clay content and 0.79 and 0.73 for OM. Independent validation of ECe, clay content and OM maps with 32 soil samples showed the better performance of the MARS models, with R2 = 0.81, 0.89 and 0.73, respectively, compared to R2 = 0.78, 0.87 and 0.71 for the PLSR models. The results indicated that MARS is a more suitable and superior modeling technique than PLSR for the estimation and mapping of soil salinity (ECe, clay content and OM. The method developed in this paper was found to be reliable and accurate for digital soil mapping in arid and semi-arid environments.
Institute of Scientific and Technical Information of China (English)
WANG XiaoGuang; FU Hong-Chen
2001-01-01
We introduce new kinds of states of quantized radiation fields, which are the superpositions of negative binomial states. They exhibit remarkable nonclassical properties and reduce to Schrodinger cat states in a certain limit.The algebras involved in the even and odd negative binomial states turn out to be generally deformed oscillator algebras.It is found that the even and odd negative binomial states satisfy the same eigenvalue equation with the same eigenvalue and they can be viewed as two-photon nonlinear coherent states. Two methods of generating such the states are proposed.``
Statistical properties of two interacting soft spheres in a hard spherical pore
Kim, Soon-Chul
2015-06-01
The structure and thermodynamics of two soft spheres, whose interactions include the soft repulsion and attraction, confined in a hard spherical pore have been considered. The exact partition function, one-body density, and equation of state have been obtained using the Fourier transform method. The pore-size and potential dependence of the structural and thermodynamic properties have been investigated. The two penetrable square-well spheres shows a negative compressibility of the van der Waals type, which imitates the phase transition of many particle system. The van der Waals instability for two penetrable square-well spheres has been studied.
Vogel, Peter; Klar, Manuel; Schlüter, Andreas; Knippertz, Peter; Fink, Andreas H.; Gneiting, Tilmann
2017-04-01
Precipitation forecasts for one up to several days are of high socioeconomic importance for agriculturally dominated societies in West Africa, regarding both the occurrence as well as the amount of precipitation. However, disappointingly forecasts based on numerical weather prediction models and even statistically postprocessed forecasts still do not outperform simple reference forecasts such as climatology or persistence. More elaborate statistical forecasts can hopefully lead to an improvement in the quality of precipitation forecasts above climatological or persistent ones. In this contribution, we concentrate on the potential of statistical forecasts to predict the occurrence of precipitation, while the prediction of the amount will be addressed in the future. Using increasingly sophisticated statistical models, we start with forecasts solely relying on the spatio-temporal information contained in precipitation observations. With the necessity of a full spatial coverage of precipitation observations in order to understand its spatio-temporal properties, we rely on Tropical Rainfall Measuring Mission (TRMM) observations and use accumulation periods of 1 to 5 days for the monsoon seasons from May to mid-October of the years 2007 to 2014. Especially for the full monsoon from the end of June to the end of September, the precipitation fields exhibit clear spatio-temporal information that is meteorologically interpretable and statistically meaningful. Using Markov models, we do in fact find an increased forecast quality for this period. While such forecasts already outperform persistent and climatological forecasts for the full monsoon, the forecast quality increases further and also covers the whole monsoon period from May to mid-October, when we add additional predictors. We find the activity of tropical waves such as Kelvin or African Easterly waves or the Madden-Julian Oscillation to be informative predictors and test for additional predictors closely linked to
Energy Technology Data Exchange (ETDEWEB)
Diletti, G.; Scortichini, G.; Conte, A.; Migliorati, G.; Caporale, V. [Ist. Zooprofilattico Sperimentale dell' Abruzzo e del Molise (Italy)
2004-09-15
PCDD/Fs levels exceeding the European Union (EU) tolerance limit were detected in milk and animal feed samples collected in Campania region in the years 2001-2003, as reported in a previous paper1. The analyses were performed on milk samples from different animal species (cow, sheep, goat and buffalo) and on animal feed samples (silage, hay, grass, cereals, premixes and mixed feeds) permitting to assess the levels and the geographical extension of the contamination. The preliminary results of this survey had given clear indications of the dioxin contamination of feedingstuffs and their contribution to the high PCDD/Fs levels recorded in milk but a more detailed analysis was needed in order to confirm the previous observations. Aim of this work is the evaluation of the correlation between the PCDD/Fs levels and patterns found in milk and animal feed samples through the statistical analysis of the congeners profiles and concentrations. Moreover, the typical congeners profiles of milk samples taken in the area under investigation were compared to those obtained from samples collected in the framework of the National Residues Surveillance Plan (NRSP) in 2003. The contamination phenomenon was also studied by means of the spatial correlation analysis.
Harkness, Mark; Fisher, Angela; Lee, Michael D; Mack, E Erin; Payne, Jo Ann; Dworatzek, Sandra; Roberts, Jeff; Acheson, Carolyn; Herrmann, Ronald; Possolo, Antonio
2012-04-01
A large, multi-laboratory microcosm study was performed to select amendments for supporting reductive dechlorination of high levels of trichloroethylene (TCE) found at an industrial site in the United Kingdom (UK) containing dense non-aqueous phase liquid (DNAPL) TCE. The study was designed as a fractional factorial experiment involving 177 bottles distributed between four industrial laboratories and was used to assess the impact of six electron donors, bioaugmentation, addition of supplemental nutrients, and two TCE levels (0.57 and 1.90 mM or 75 and 250 mg/L in the aqueous phase) on TCE dechlorination. Performance was assessed based on the concentration changes of TCE and reductive dechlorination degradation products. The chemical data was evaluated using analysis of variance (ANOVA) and survival analysis techniques to determine both main effects and important interactions for all the experimental variables during the 203-day study. The statistically based design and analysis provided powerful tools that aided decision-making for field application of this technology. The analysis showed that emulsified vegetable oil (EVO), lactate, and methanol were the most effective electron donors, promoting rapid and complete dechlorination of TCE to ethene. Bioaugmentation and nutrient addition also had a statistically significant positive impact on TCE dechlorination. In addition, the microbial community was measured using phospholipid fatty acid analysis (PLFA) for quantification of total biomass and characterization of the community structure and quantitative polymerase chain reaction (qPCR) for enumeration of Dehalococcoides organisms (Dhc) and the vinyl chloride reductase (vcrA) gene. The highest increase in levels of total biomass and Dhc was observed in the EVO microcosms, which correlated well with the dechlorination results.
Statistical properties of exoplanets II. Metallicity, orbital parameters, and space velocities
Santos, N C; Mayor, M; Rebolo, R; Udry, S
2003-01-01
In this article we present a detailed spectroscopic analysis of more than 50 extra-solar planet host stars. Stellar atmospheric parameters and metallicities are derived using high resolution and high S/N spectra. The spectroscopy results, added to the previous studies, imply that we have access to a large and uniform sample of metallicities for about 80 planet hosts stars. We make use of this sample to confirm the metal-rich nature of stars with planets, and to show that the planetary frequency is rising as a function of the [Fe/H]. Furthermore, the source of this high metallicity is shown to have most probably an ``primordial'' source, confirming previous results. The comparison of the orbital properties (period and eccentricity) and minimum masses of the planets with the stellar properties also reveal some emerging but still not significant trends. These are discussed and some explanations are proposed. Finally, we show that the planet host stars included in the CORALIE survey have similar kinematical prope...
Physical properties of solar polar jets: A statistical study with Hinode XRT data
Paraschiv, A R; Sterling, A C
2015-01-01
The target of this work is to investigate the physical nature of polar jets in the solar corona and their possible contribution to coronal heating and solar wind flow based on the analysis of X-ray images acquired by the Hinode XRT telescope. We estimate the di?erent forms of energy associated with many of these small-scale eruptions, in particular the kinetic energy and enthalpy. Two Hinode XRT campaign datasets focusing on the two polar coronal holes were selected to analyze the physical properties of coronal jets; the analyzed data were acquired using a series of three XRT filters. Typical kinematical properties (e.g., length, thickness, lifetime, ejection rate, and velocity) of 18 jets are evaluated from the observed sequences, thus providing information on their possible contribution to the fast solar wind flux escaping from coronal holes. Electron temperatures and densities of polar-jet plasmas are also estimated using ratios of the intensities observed in di?erent filters. We find that the largest amou...
Interfacial properties of statistical copolymer brushes in contact with homopolymer melts.
Trombly, David M; Pryamitsyn, Victor; Ganesan, Venkat
2011-04-21
We use polymer self-consistent field theory to quantify the interfacial properties of random copolymer brushes (AB) in contact with a homopolymer melt chemically identical to one of the blocks (A). We calculate the interfacial widths and interfacial energies between the melt and the brush as a function of the relative chain sizes, grafting densities, compositions of the random copolymer in the brush, and degree of chemical incompatibility between the A and B species. Our results indicate that the interfacial energies between the melt and the brush increase (signifying expulsion of the free chains from the brush) with increasing grafting density, chemical incompatibility between A and B components, and size of the free chains relative to the grafted chains. We also compare the interfacial energies of random copolymers of different sequence characteristics and find that, except for the case of very blocky or proteinlike chains, blockiness of the copolymer has only little effect on interfacial properties. Our results for interfacial energies are rationalized based on the concept of an "effective volume fraction" of the brush copolymers, f(eff), which quantifies the chemical composition of the brush segments in the interfacial zone between the brush and melt copolymers. Using this concept, we modify the strong-stretching theory of brush-melt interfaces to arrive at a simple model whose results qualitatively agree with our results from self-consistent field theory. We discuss the ramifications of our results for the design of neutral surfaces.
Combrisson, Etienne; Jerbi, Karim
2015-07-30
Machine learning techniques are increasingly used in neuroscience to classify brain signals. Decoding performance is reflected by how much the classification results depart from the rate achieved by purely random classification. In a 2-class or 4-class classification problem, the chance levels are thus 50% or 25% respectively. However, such thresholds hold for an infinite number of data samples but not for small data sets. While this limitation is widely recognized in the machine learning field, it is unfortunately sometimes still overlooked or ignored in the emerging field of brain signal classification. Incidentally, this field is often faced with the difficulty of low sample size. In this study we demonstrate how applying signal classification to Gaussian random signals can yield decoding accuracies of up to 70% or higher in two-class decoding with small sample sets. Most importantly, we provide a thorough quantification of the severity and the parameters affecting this limitation using simulations in which we manipulate sample size, class number, cross-validation parameters (k-fold, leave-one-out and repetition number) and classifier type (Linear-Discriminant Analysis, Naïve Bayesian and Support Vector Machine). In addition to raising a red flag of caution, we illustrate the use of analytical and empirical solutions (binomial formula and permutation tests) that tackle the problem by providing statistical significance levels (p-values) for the decoding accuracy, taking sample size into account. Finally, we illustrate the relevance of our simulations and statistical tests on real brain data by assessing noise-level classifications in Magnetoencephalography (MEG) and intracranial EEG (iEEG) baseline recordings. Copyright © 2015 Elsevier B.V. All rights reserved.
Statistical properties of $^{243}$Pu, and $^{242}$Pu(n,$\\gamma$) cross section calculation
Laplace, T A; Guttormsen, M; Larsen, A C; Bleuel, D L; Bernstein, L A; Goldblum, B L; Siem, S; Garotte, F L Bello; Brown, J A; Campo, L Crespo; Eriksen, T K; Giacoppo, F; Görgen, A; Hadyńska-Klȩk, K; Henderson, R A; Klintefjord, M; Lebois, M; Renstrøm, T; Rose, S J; Sahin, E; Tornyi, T G; Tveten, G M; Voinov, A; Wiedeking, M; Wilson, J N; Younes, W
2015-01-01
The level density and gamma-ray strength function (gammaSF) of 243Pu have been measured in the quasi-continuum using the Oslo method. Excited states in 243Pu were populated using the 242Pu(d,p) reaction. The level density closely follows the constant-temperature level density formula for excitation energies above the pairing gap. The gammaSF displays a double-humped resonance at low energy as also seen in previous investigations of actinide isotopes. The structure is interpreted as the scissors resonance and has a centroid of omega_{SR}=2.42(5)MeV and a total strength of B_{SR}=10.1(15)mu_N^2, which is in excellent agreement with sum-rule estimates. The measured level density and gammaSF were used to calculate the 242Pu(n,gamma) cross section in a neutron energy range for which there were previously no measured data.
Chapter 3 – Phenomenology of Tsunamis: Statistical Properties from Generation to Runup
Geist, Eric L.
2015-01-01
Observations related to tsunami generation, propagation, and runup are reviewed and described in a phenomenological framework. In the three coastal regimes considered (near-field broadside, near-field oblique, and far field), the observed maximum wave amplitude is associated with different parts of the tsunami wavefield. The maximum amplitude in the near-field broadside regime is most often associated with the direct arrival from the source, whereas in the near-field oblique regime, the maximum amplitude is most often associated with the propagation of edge waves. In the far field, the maximum amplitude is most often caused by the interaction of the tsunami coda that develops during basin-wide propagation and the nearshore response, including the excitation of edge waves, shelf modes, and resonance. Statistical distributions that describe tsunami observations are also reviewed, both in terms of spatial distributions, such as coseismic slip on the fault plane and near-field runup, and temporal distributions, such as wave amplitudes in the far field. In each case, fundamental theories of tsunami physics are heuristically used to explain the observations.
Hasan, A; Maloney, C E
2014-12-01
We compute the effective dispersion and vibrational density of states (DOS) of two-dimensional subregions of three-dimensional face-centered-cubic crystals using both a direct projection-inversion technique and a Monte Carlo simulation based on a common underlying Hamiltonian. We study both a (111) and (100) plane. We show that for any given direction of wave vector, both (111) and (100) show an anomalous ω(2)∼q regime at low q where ω(2) is the energy associated with the given mode and q is its wave number. The ω(2)∼q scaling should be expected to give rise to an anomalous DOS, D(ω), at low ω: D(ω)∼ω(3) rather than the conventional Debye result: D(ω)∼ω(2). The DOS for (100) looks to be consistent with D(ω)∼ω(3), while (111) shows something closer to the conventional Debye result at the smallest frequencies. In addition to the direct projection-inversion calculation, we perform Monte Carlo simulations to study the effects of finite sampling statistics. We show that finite sampling artifacts act as an effective disorder and bias D(ω), giving a behavior closer to D(ω)∼ω(2) than D(ω)∼ω(3). These results should have an important impact on the interpretation of recent studies of colloidal solids where the two-point displacement correlations can be obtained directly in real-space via microscopy.
Statistical properties of kinetic and total energy densities in reverberant spaces.
Jacobsen, Finn; Molares, Alfonso Rodríguez
2010-04-01
Many acoustical measurements, e.g., measurement of sound power and transmission loss, rely on determining the total sound energy in a reverberation room. The total energy is usually approximated by measuring the mean-square pressure (i.e., the potential energy density) at a number of discrete positions. The idea of measuring the total energy density instead of the potential energy density on the assumption that the former quantity varies less with position than the latter goes back to the 1930s. However, the phenomenon was not analyzed until the late 1970s and then only for the region of high modal overlap, and this analysis has never been published. Moreover, until fairly recently, measurement of the total sound energy density required an elaborate experimental arrangement based on finite-difference approximations using at least four amplitude and phase matched pressure microphones. With the advent of a three-dimensional particle velocity transducer, it has become somewhat easier to measure total rather than only potential energy density in a sound field. This paper examines the ensemble statistics of kinetic and total sound energy densities in reverberant enclosures theoretically, experimentally, and numerically.
Tarasova, Irina A; Goloborodko, Anton A; Perlova, Tatyana Y; Pridatchenko, Marina L; Gorshkov, Alexander V; Evreinov, Victor V; Ivanov, Alexander R; Gorshkov, Mikhail V
2015-07-07
The theory of critical chromatography for biomacromolecules (BioLCCC) describes polypeptide retention in reversed-phase HPLC using the basic principles of statistical thermodynamics. However, whether this theory correctly depicts a variety of empirical observations and laws introduced for peptide chromatography over the last decades remains to be determined. In this study, by comparing theoretical results with experimental data, we demonstrate that the BioLCCC: (1) fits the empirical dependence of the polypeptide retention on the amino acid sequence length with R(2) > 0.99 and allows in silico determination of the linear regression coefficients of the log-length correction in the additive model for arbitrary sequences and lengths and (2) predicts the distribution coefficients of polypeptides with an accuracy from 0.98 to 0.99 R(2). The latter enables direct calculation of the retention factors for given solvent compositions and modeling of the migration dynamics of polypeptides separated under isocratic or gradient conditions. The obtained results demonstrate that the suggested theory correctly relates the main aspects of polypeptide separation in reversed-phase HPLC.
To Identify the Important Soil Properties Affecting Dinoseb Adsorption with Statistical Analysis
Directory of Open Access Journals (Sweden)
Yiqing Guan
2013-01-01
Full Text Available Investigating the influences of soil characteristic factors on dinoseb adsorption parameter with different statistical methods would be valuable to explicitly figure out the extent of these influences. The correlation coefficients and the direct, indirect effects of soil characteristic factors on dinoseb adsorption parameter were analyzed through bivariate correlation analysis, and path analysis. With stepwise regression analysis the factors which had little influence on the adsorption parameter were excluded. Results indicate that pH and CEC had moderate relationship and lower direct effect on dinoseb adsorption parameter due to the multicollinearity with other soil factors, and organic carbon and clay contents were found to be the most significant soil factors which affect the dinoseb adsorption process. A regression is thereby set up to explore the relationship between the dinoseb adsorption parameter and the two soil factors: the soil organic carbon and clay contents. A 92% of the variation of dinoseb sorption coefficient could be attributed to the variation of the soil organic carbon and clay contents.
Thorium-Free Versus Thoriated Plasma Gun Electrodes: Statistical Evaluation of Coating Properties
Colmenares-Angulo, Jose; Molz, Ronald; Hawley, David; Seshadri, Ramachandran Chidambaram
2016-04-01
Industries throughout the world today have an increased awareness of environmental, health, and safety issues. This, together with recent Nuclear Regulatory Commission changes concerning source material (e.g., thorium) has added complexity in the supply chain of thoriated tungsten commonly used in plasma spray gun spares. In the interest of a safer and more sustainable work environment, Oerlikon Metco has developed thorium-free material solutions proven to have longer service life than conventional thoriated spares. This work reports on the effect, if any, caused by tungsten compositional changes and extended service life in coating properties. Microstructure, coating efficiency parameters, hardness, particle state, in situ coating stress, and ex situ modulus are evaluated over the service life duration of the nozzle, comparing coatings with thoriated and non-thoriated nozzles and electrodes with the same spray parameters.
Investigation of the Statistical Properties of Stable Eu Nuclei using Neutron-Capture Reactions
Energy Technology Data Exchange (ETDEWEB)
Agvaanluvsan, U; Alpizar-Vicente, A; Becker, J A; Becvar, F; Bredeweg, T A; Clement, R; Esch, E; Folden, III, C M; Hatarik, R; Haight, R C; Hoffman, D C; Krticka, M; Macri, R A; Mitchell, G E; Nitsche, H; O' Donnell, J M; Parker, W; Reifarth, R; Rundberg, R S; Schwantes, J M; Sheets, S A; Ullmann, J L; Vieira, D J; Wilhelmy, J B; Wilk, P; Wouters, J M; Wu, C Y
2005-10-04
Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for {sup 151,153}Eu targets. The highly efficient DANCE (Detector for Advanced Neutron Capture Experiments) array coupled with the intense neutron beam at Los Alamos Neutron Science Center is used for the experiment. Stable Eu isotopes mass separated and electroplated on Be backings were used. Properties of well-resolved, strong resonances in two Eu nuclei are examined. The parameters for most of these resonances are known. Detailed multiplicity information for each resonance is obtained employing the high granularity of the DANCE array. The radiative decay cascades corresponding to each resonance are obtained in the experiment. The measurements are compared to simulation of these cascades which calculated with various models for the radiative strength function. Comparison between the experimental data and simulation provides an opportunity to investigate the average quantities.
Engin, Irfan Celal; Bayram, Fatih; Yasitli, Nazmi Erhan
2013-07-01
In a processing plant, natural stone can be cut by methods such as circular sawing (CS), frame sawing (FS), water jet cutting (WJC) and abrasive water jet cutting (AWJC). The efficiency of cutting systems can be compared using various parameters. In this study, the specific energy values were determined and compared to evaluate the efficiency of rock-cutting methods. Rock-cutting experiments were performed on 12 different types of rock samples using a circular sawing machine and an AWJC machine. The experimental results showed that the specific energy values in AWJC were generally higher than in CS. In addition, the relationships between specific energy values and rock properties were explained in this study. The Shore hardness and abrasion resistance were found to be strongly related to the specific energy values, and according to these parameters prediction charts of specific energy values were created.
Flanigan, Patrick M; Niemeyer, Emily D
2014-12-01
In this study, we determined the effect of cultivar on total and individual anthocyanin concentrations and phenolic acid levels in eight purple basil varieties and examined the relationship between anthocyanin content, phenolic acid composition, and antioxidant properties. Cultivar had a significant influence on total anthocyanin concentrations as well as individual anthocyanin composition. The four major basil anthocyanins (labelled A-D) were quantified and cultivar had a statistically significant effect on anthocyanins B (p<0.01), C (p<0.01), and D (p<0.01), but not on anthocyanin A (p=0.94). Cultivar did not have a significant effect on total phenolic levels, although it did influence the concentration of some individual phenolic acids, including caftaric (p=0.03) and chicoric (p=0.04) acids. Although total phenolic and anthocyanin levels correlated with measured FRAP antioxidant capacities, for some cultivars the individual phenolic acid and anthocyanin composition was also an important factor affecting the antioxidant properties.
Institute of Scientific and Technical Information of China (English)
Guillaume Brysbaert; Sebastian Noth; Arndt Benecke
2007-01-01
We have previously developed a combined signal/variance distribution model that accounts for the particular statistical properties of datasets generated on the Applied Biosystems AB1700 transcriptome system. Here we show that this model can be efficiently used to generate synthetic datasets with statistical properties virtually identical to those of the actual data by aid of the JAVA application ace.map creator 1.0 that we have developed. The fundamentally different structure of AB1700 transcriptome profiles requires re-evaluation, adaptation, or even redevelopment of many of the standard microarray analysis methods in order to avoid misinterpretation of the data on the one hand, and to draw full benefit from their increased specificity and sensitivity on the other hand. Our composite data model and the ace.map creator 1.0 application thereby not only present proof of the correctness of our parameter estimation, but also provide a tool for the generation of synthetic test data that will be useful for further development and testing of analysis methods.
Verma, Meetu
2014-01-01
The extensive database of high-resolution G-band images observed with the Hinode/SOT is a unique resource to derive statistical properties of pores using advanced digital image processing techniques. The study is based on two data sets: (1) Photometric and morphological properties inferred from single G-band images cover almost seven years from 2006 October 25 to 2013 August 31. (2) Horizontal flow fields have been derived from 356 one-hour sequences of G-band images using LCT for a shorter period of time from 2006 November 3 to 2008 January 6 comprising 13 active regions. A total of 7643/2863 (single/time-averaged) pores builds the foundation of the statistical analysis. Pores are preferentially observed at low latitudes in the southern hemisphere during the deep minimum of solar cycle No. 23. This imbalance reverses during the rise of cycle No. 24, when the pores migrate from high to low latitudes. Pores are rarely encountered in quiet-Sun G-band images, and only about 10% of pores exists in isolation. In g...
Yura, Harold T; Fields, Renny A
2011-06-20
Level crossing statistics is applied to the complex problem of atmospheric turbulence-induced beam wander for laser propagation from ground to space. A comprehensive estimate of the single-axis wander angle temporal autocorrelation function and the corresponding power spectrum is used to develop, for the first time to our knowledge, analytic expressions for the mean angular level crossing rate and the mean duration of such crossings. These results are based on an extension and generalization of a previous seminal analysis of the beam wander variance by Klyatskin and Kon. In the geometrical optics limit, we obtain an expression for the beam wander variance that is valid for both an arbitrarily shaped initial beam profile and transmitting aperture. It is shown that beam wander can disrupt bidirectional ground-to-space laser communication systems whose small apertures do not require adaptive optics to deliver uniform beams at their intended target receivers in space. The magnitude and rate of beam wander is estimated for turbulence profiles enveloping some practical laser communication deployment options and suggesting what level of beam wander effects must be mitigated to demonstrate effective bidirectional laser communication systems.
Ilyas, Asim; Shah, Munir H
2017-02-28
The present study was designed to investigate the role of selected essential and toxic metals in the onset/prognosis of valvular heart disease (VHD). Nitric acid-perchloric acid based wet digestion procedure was used for the quantification of the metals by flame atomic absorption spectrophotometry. Comparative appraisal of the data revealed that average levels of Cd, Co, Cr, Fe, K, Li, Mn and Zn were significantly higher in blood of VHD patients, while the average concentration of Ca was found at elevated level in controls (P < 0.05). However, Cu, Mg, Na, Sr and Pb depicted almost comparable levels in the blood of both donor groups. The correlation study revealed significantly different mutual associations among the metals in the blood of VHD patients compared with the controls. Multivariate statistical methods showed substantially divergent grouping of the metals for the patients and controls. Some significant differences in the metal concentrations were also observed with gender, abode, dietary/smoking habits and occupations of both donor groups. Overall, the study demonstrated that disproportions in the concentrations of essential/toxic metals in the blood are involved in pathogenesis of the disease.
Statistical properties of coronal hole rotation rates: Are they linked to the solar interior?
Bagashvili, S. R.; Shergelashvili, B. M.; Japaridze, D. R.; Chargeishvili, B. B.; Kosovichev, A. G.; Kukhianidze, V.; Ramishvili, G.; Zaqarashvili, T. V.; Poedts, S.; Khodachenko, M. L.; De Causmaecker, P.
2017-07-01
Context. The present paper discusses results of a statistical study of the characteristics of coronal hole (CH) rotation in order to find connections to the internal rotation of the Sun. Aims: The goal is to measure CH rotation rates and study their distribution over latitude and their area sizes. In addition, the CH rotation rates are compared with the solar photospheric and inner layer rotational profiles. Methods: We study CHs observed within ± 60° latitude and longitude from the solar disc centre during the time span from the 1 January 2013 to 20 April 2015, which includes the extended peak of solar cycle 24. We used data created by the spatial possibilistic clustering algorithm (SPoCA), which provides the exact location and characterisation of solar coronal holes using SDO/AIA193 Å channel images. The CH rotation rates are measured with four-hour cadence data to track variable positions of the CH geometric centre. Results: North-south asymmetry was found in the distribution of coronal holes: about 60 percent were observed in the northern hemisphere and 40 percent were observed in the southern hemisphere. The smallest and largest CHs were present only at high latitudes. The average sidereal rotation rate for 540 examined CHs is 13.86( ± 0.05)°/d. Conclusions: The latitudinal characteristics of CH rotation do not match any known photospheric rotation profile. The CH angular velocities exceed the photospheric angular velocities at latitudes higher than 35-40 degrees. According to our results, the CH rotation profile perfectly coincides with tachocline and the lower layers of convection zone at around 0.71 R⊙; this indicates that CHs may be linked to the solar global magnetic field, which originates in the tachocline region.
Taylor, Kirsten I; Devereux, Barry J; Acres, Kadia; Randall, Billi; Tyler, Lorraine K
2012-03-01
Conceptual representations are at the heart of our mental lives, involved in every aspect of cognitive functioning. Despite their centrality, a long-standing debate persists as to how the meanings of concepts are represented and processed. Many accounts agree that the meanings of concrete concepts are represented by their individual features, but disagree about the importance of different feature-based variables: some views stress the importance of the information carried by distinctive features in conceptual processing, others the features which are shared over many concepts, and still others the extent to which features co-occur. We suggest that previously disparate theoretical positions and experimental findings can be unified by an account which claims that task demands determine how concepts are processed in addition to the effects of feature distinctiveness and co-occurrence. We tested these predictions in a basic-level naming task which relies on distinctive feature information (Experiment 1) and a domain decision task which relies on shared feature information (Experiment 2). Both used large-scale regression designs with the same visual objects, and mixed-effects models incorporating participant, session, stimulus-related and feature statistic variables to model the performance. We found that concepts with relatively more distinctive and more highly correlated distinctive relative to shared features facilitated basic-level naming latencies, while concepts with relatively more shared and more highly correlated shared relative to distinctive features speeded domain decisions. These findings demonstrate that the feature statistics of distinctiveness (shared vs. distinctive) and correlational strength, as well as the task demands, determine how concept meaning is processed in the conceptual system.
Sadovskii, Michael V
2012-01-01
This volume provides a compact presentation of modern statistical physics at an advanced level. Beginning with questions on the foundations of statistical mechanics all important aspects of statistical physics are included, such as applications to ideal gases, the theory of quantum liquids and superconductivity and the modern theory of critical phenomena. Beyond that attention is given to new approaches, such as quantum field theory methods and non-equilibrium problems.
de Lapparent, Valérie; Bertin, Emmanuel
2011-01-01
The EFIGI catalogue of 4458 galaxies provides a reference database of the morphological properties of nearby galaxies, with 16 shape attributes describing their various dynamical components, their texture and environment, and with a dense sampling of all Hubble types. This catalogue allows us to derive a quantitative description of the Hubble Sequence in terms of the specific morphological features of the various types. The variations of the EFIGI morphological attributes with type confirm that the Hubble sequence is a decreasing sequence of bulge-to-total ratio and an increasing sequence of disk contribution to the total flux. There is nevertheless a large dispersion of approximately 5 types for a given bulge-to-total ratio, due to the fact that the Hubble sequence is primarily based on the strength and pitch angle of the spiral arms, independently from the bulge-to-total ratio. The grand spiral design is also related to a steep decrease in visible dust from types Sb to Sbc-Sc. In contrast, the scattered and...
Statistical Properties of the IntraCluster Light from SDSS Image Stacking
Zibetti, Stefano
2007-01-01
The presence of a diffuse stellar component in galaxy clusters has been established by a number of observational works in recent years. In this contribution I summarize our results (Zibetti et al. 2005) obtained by stacking SDSS images of 683 clusters, selected with the maxBCG algorithm at 0.2< z <0.3. Thanks to our large sample and the advantages of image stacking applied to SDSS images, we are able to measure the systematic properties of the intracluster light (ICL) with very high accuracy. We find that the average surface brightness of the ICL ranges between 26 and 32 mag/arcsec^2, and constantly declines from 70 kpc cluster-centric distance (i.e. distance from the BCG) to 700 kpc. The fraction of diffuse light over the total light (including galaxies), monotonically declines from ~50 to <~5% over the same range of distances, thus showing that the ICL is more easily produced close to the bottom of a cluster's potential well. Clusters lacking a bright BCG hardly build up a large amount of intraclus...
Yasmin, Y.; Mazlee, M. N.; Norzilah, A. H.; Shamsul, J. B.; Azmi, R.; Chan, W. H.
2016-07-01
In this present study, the porous anorthite ceramics were prepared from white clay and precipitated calcium carbonate via polymeric foam replication method. The effects of various precipitated calcium carbonate additions (0, 10, 15, and 25 wt.%) on the properties of porous anorthite ceramics have been studied. The main phase that revealed after the additions of 20 and 25 wt.% of precipitated calcium carbonate was anorthite (CaO.Al2O3.2SiO2). The porosity of the porous anorthite ceramics was increased (from 67 to 77 percent) with the increasing amount of precipitated calcium carbonate. Meanwhile, the density of the porous anorthite ceramics was increased (from 0.463 to 0.703 g/cm3) with the increasing amount of precipitated calcium carbonate. The flexural strength of porous anorthite ceramics consisting of predominantly anorthite phase are ranged from 0.24 to 1.23 MPa. Finally, the correlation between the flexural strength on the foam density has been studied. The flexural strength was increased when the foam density increases.
Galactic production of 138La: Impact of 138,139La statistical properties
Directory of Open Access Journals (Sweden)
B.V. Kheswa
2015-05-01
Full Text Available The γ-ray strength functions and nuclear level densities of 138La and 139La have been measured below the neutron separation energies. These new data were used to calculate astrophysical Maxwellian-averaged (n,γ cross-sections to investigate the production and destruction of the p-nucleus 138La in the photodisintegration process. The results confirm the underproduction of 138La in the p-process with respect to the observed abundances and strongly support the ν-process through νe capture on 138Ba as the main contributor to the synthesis of 138La in Type II supernovae.
General and specific statistical properties of foreign exchange markets during a financial crash
Li, Wei-Shen; Tsai, Yun-Jie; Shen, Yu-Hsien; Liaw, Sy-Sang
2016-06-01
We investigate minute-by-minute foreign exchange rate (FX) data of 14 currencies with different exchange-rate regimes during a financial crash, and divide these data into several stages according to their respective tendencies: depreciation stage (stage 1), fluctuating stage (stage 2), and appreciation stage (stage 3). The tail distribution of FX rate returns satisfies a power-law structure for different types of currencies. We find the absolute value of the power-law exponent is smaller in emerging markets than in developed markets, especially during the stage 1, and is greatest in pegged currencies. We also find that the correlation properties of the FX rate return series have quite disparate results among the various types of currencies. Currencies in developed markets respectively have weak persistence and anti-persistence in short and long timescales; whereas the pegged currencies and currencies in emerging markets show different degrees of anti-persistence in various timescales. Further analyses on the data in divided stages indicate that emerging markets and pegged currencies have more prominent dual fractal structures after the depreciation stage, while the developed markets do not. Hurst exponent analyses on the sign series yield similar results to that on the original return series for most currencies. The magnitude series of the returns provide some unique results during a crash. The developed market currencies have strong persistence and exhibit a weaker correlation in the depreciation and appreciation stages. In contrast, the currencies of emerging markets as well as pegged currencies fail to show such a transformation, but rather show a constant-correlation behavior in the corresponding stages of a crash. These results indicate that external shocks exert different degrees of influence during different stages of the crash in various markets.
The Kullback-Leibler Divergence as an Estimator of the Statistical Properties of CMB Maps
Ben-David, Assaf; Jackson, Andrew D
2015-01-01
The identification of unsubtracted foreground residuals in the cosmic microwave background maps on large scales is of crucial importance for the analysis of polarization signals. These residuals add a non-Gaussian contribution to the data. We propose the Kullback-Leibler (KL) divergence as an effective, non-parametric test on the one-point probability distribution function of the data. With motivation in information theory, the KL divergence takes into account the entire range of the distribution and is highly non-local. We demonstrate its use by analyzing the large scales of the Planck 2013 SMICA temperature fluctuation map and find it consistent with the expected distribution at a level of 6%. Comparing the results to those obtained using the more popular Kolmogorov-Smirnov test, we find the two methods to be in general agreement.
Directory of Open Access Journals (Sweden)
Turnbull Arran K
2012-08-01
Full Text Available Abstract Background Affymetrix GeneChips and Illumina BeadArrays are the most widely used commercial single channel gene expression microarrays. Public data repositories are an extremely valuable resource, providing array-derived gene expression measurements from many thousands of experiments. Unfortunately many of these studies are underpowered and it is desirable to improve power by combining data from more than one study; we sought to determine whether platform-specific bias precludes direct integration of probe intensity signals for combined reanalysis. Results Using Affymetrix and Illumina data from the microarray quality control project, from our own clinical samples, and from additional publicly available datasets we evaluated several approaches to directly integrate intensity level expression data from the two platforms. After mapping probe sequences to Ensembl genes we demonstrate that, ComBat and cross platform normalisation (XPN, significantly outperform mean-centering and distance-weighted discrimination (DWD in terms of minimising inter-platform variance. In particular we observed that DWD, a popular method used in a number of previous studies, removed systematic bias at the expense of genuine biological variability, potentially reducing legitimate biological differences from integrated datasets. Conclusion Normalised and batch-corrected intensity-level data from Affymetrix and Illumina microarrays can be directly combined to generate biologically meaningful results with improved statistical power for robust, integrated reanalysis.
Multivariate statistical analysis treatment of DSC thermal properties for animal fat adulteration.
Dahimi, Omar; Rahim, Alina Abdul; Abdulkarim, S M; Hassan, Mohd Sukri; Hashari, Shazamawati B T Zam; Mashitoh, A Siti; Saadi, Sami
2014-09-01
The adulteration of edible fats is a kind of fraud that impairs the physical and chemical features of the original lipid materials. It has been detected in various food, pharmaceutical and cosmeceutical products. Differential scanning calorimetry (DSC) is the robust thermo-analytical machine that permits to fingerprint the primary crystallisation of triacylglycerols (TAGs) molecules and their transition behaviours. The aims of this study was to assess the cross-contamination caused by lard concentration of 0.5-5% in the mixture systems containing beef tallow (BT) and chicken fat (CF) separately. TAGs species of pure and adulterated lipids in relation to their crystallisation and melting parameters were studied using principal components analysis (PCA). The results showed that by using the heating profiles the discrimination of LD from BT and CF was very clear even at low dose of less than 1%. Same observation was depicted from the crystallisation profiles of BT adulterated by LD doses ranging from 0.1% to 1% and from 2% to 5%, respectively. Furthermore, CF adulterated with LD did not exhibit clear changes on its crystallisation profiles. Consequently, DSC coupled with PCA is one of the techniques that might use to monitor and differentiate the minimum adulteration levels caused by LD in different animal fats.
Cui, B.; Zhang, Y.; Yan, L.; Cai, X.
2017-09-01
Detecting the land cover changes is an important application of multi-temporal synthetic aperture radar (SAR) images. This study puts forward a novel SAR change detection method which has two-steps: change detector construction and change threshold selection. For change detector construction, considering the SAR intensity images follow the gamma distribution, the conditional probabilities of the binary hypothesis test are provided, then the log likelihood ratio (LLR) combined with the log ratio (LR) to construct a detector which can enhance the degree of change to calculate the diversity degree convenient between the two images; for change threshold selection, owing to the characteristic that the curve about the ratio value of adjacent grey-level (GL) values in normalized difference map, the normalized difference map can be segmented in three parts by two thresholds selected which correspond to the regions of unchanged, backscatter enhanced and weakened separately. And as this, the change areas can be also determined simultaneously. The experimental results on different areas and sensors indicate that the proposed algorithm is effective and feasible.
Power estimation for intellectual property-based digital systems at the architectural level
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Yaseer Arafat Durrani
2014-09-01
We present an efficient power macro-modeling technique at the architectural level for digital electronic systems. This technique estimates the power dissipation of intellectual property (IP components to their statistical knowledge of the primary inputs/outputs. During the power estimation method, the sequence of an input stream is generated by a genetic algorithm (GA using input metrics and the macro-model function to construct a set of functions that map the input metrics of a macro-block to its output metrics. Then, a Monte Carlo zero-delay simulation is performed and the power dissipation is predicted by a macro-model function. The most important contribution of the technique is that it allows fast power estimation of IP-based design by the simple addition of individual power consumption. This makes the power modeling of SoCs an easy task that permits evaluation of power features at the architectural level. In order to evaluate our model, we have constructed IP-based digital systems using different IP macro-blocks. In experiments with an individual IP macro-block the average error is 1–2% and for an entire IP-based system with interconnects, the error range is from 9% to 15%. The preliminary results are effective and our macro-model provides accurate power estimation.
Yan, Koon-Kiu; Gerstein, Mark
2011-01-01
The presence of web-based communities is a distinctive signature of Web 2.0. The web-based feature means that information propagation within each community is highly facilitated, promoting complex collective dynamics in view of information exchange. In this work, we focus on a community of scientists and study, in particular, how the awareness of a scientific paper is spread. Our work is based on the web usage statistics obtained from the PLoS Article Level Metrics dataset compiled by PLoS. The cumulative number of HTML views was found to follow a long tail distribution which is reasonably well-fitted by a lognormal one. We modeled the diffusion of information by a random multiplicative process, and thus extracted the rates of information spread at different stages after the publication of a paper. We found that the spread of information displays two distinct decay regimes: a rapid downfall in the first month after publication, and a gradual power law decay afterwards. We identified these two regimes with two distinct driving processes: a short-term behavior driven by the fame of a paper, and a long-term behavior consistent with citation statistics. The patterns of information spread were found to be remarkably similar in data from different journals, but there are intrinsic differences for different types of web usage (HTML views and PDF downloads versus XML). These similarities and differences shed light on the theoretical understanding of different complex systems, as well as a better design of the corresponding web applications that is of high potential marketing impact.
Directory of Open Access Journals (Sweden)
Koon-Kiu Yan
Full Text Available The presence of web-based communities is a distinctive signature of Web 2.0. The web-based feature means that information propagation within each community is highly facilitated, promoting complex collective dynamics in view of information exchange. In this work, we focus on a community of scientists and study, in particular, how the awareness of a scientific paper is spread. Our work is based on the web usage statistics obtained from the PLoS Article Level Metrics dataset compiled by PLoS. The cumulative number of HTML views was found to follow a long tail distribution which is reasonably well-fitted by a lognormal one. We modeled the diffusion of information by a random multiplicative process, and thus extracted the rates of information spread at different stages after the publication of a paper. We found that the spread of information displays two distinct decay regimes: a rapid downfall in the first month after publication, and a gradual power law decay afterwards. We identified these two regimes with two distinct driving processes: a short-term behavior driven by the fame of a paper, and a long-term behavior consistent with citation statistics. The patterns of information spread were found to be remarkably similar in data from different journals, but there are intrinsic differences for different types of web usage (HTML views and PDF downloads versus XML. These similarities and differences shed light on the theoretical understanding of different complex systems, as well as a better design of the corresponding web applications that is of high potential marketing impact.
Thompson, John
2015-04-01
As the Physical Review Focused Collection demonstrates, recent frontiers in physics education research include systematic investigations at the upper division. As part of a collaborative project, we have examined student understanding of several topics in upper-division thermal and statistical physics. A fruitful context for research is the Boltzmann factor in statistical mechanics: the standard derivation involves several physically justified mathematical steps as well as the invocation of a Taylor series expansion. We have investigated student understanding of the physical significance of the Boltzmann factor as well as its utility in various circumstances, and identified various lines of student reasoning related to the use of the Boltzmann factor. Results from written data as well as teaching interviews suggest that many students do not use the Boltzmann factor when answering questions related to probability in applicable physical situations, even after lecture instruction. We designed an inquiry-based tutorial activity to guide students through a derivation of the Boltzmann factor and to encourage deep connections between the physical quantities involved and the mathematics. Observations of students working through the tutorial suggest that many students at this level can recognize and interpret Taylor series expansions, but they often lack fluency in creating and using Taylor series appropriately, despite previous exposure in both calculus and physics courses. Our findings also suggest that tutorial participation not only increases the prevalence of relevant invocation of the Boltzmann factor, but also helps students gain an appreciation of the physical implications and meaning of the mathematical formalism behind the formula. Supported in part by NSF Grants DUE-0817282, DUE-0837214, and DUE-1323426.
Energy Technology Data Exchange (ETDEWEB)
Eliazar, Iddo, E-mail: eliazar@post.tau.ac.il
2017-05-15
The exponential, the normal, and the Poisson statistical laws are of major importance due to their universality. Harmonic statistics are as universal as the three aforementioned laws, but yet they fall short in their ‘public relations’ for the following reason: the full scope of harmonic statistics cannot be described in terms of a statistical law. In this paper we describe harmonic statistics, in their full scope, via an object termed harmonic Poisson process: a Poisson process, over the positive half-line, with a harmonic intensity. The paper reviews the harmonic Poisson process, investigates its properties, and presents the connections of this object to an assortment of topics: uniform statistics, scale invariance, random multiplicative perturbations, Pareto and inverse-Pareto statistics, exponential growth and exponential decay, power-law renormalization, convergence and domains of attraction, the Langevin equation, diffusions, Benford’s law, and 1/f noise. - Highlights: • Harmonic statistics are described and reviewed in detail. • Connections to various statistical laws are established. • Connections to perturbation, renormalization and dynamics are established.
Radiation properties and emissivity parameterization of high level thin clouds
Wu, M.-L. C.
1984-01-01
To parameterize emissivity of clouds at 11 microns, a study has been made in an effort to understand the radiation field of thin clouds. The contributions to the intensity and flux from different sources and through different physical processes are calculated by using the method of successive orders of scattering. The effective emissivity of thin clouds is decomposed into the effective absorption emissivity, effective scattering emissivity, and effective reflection emissivity. The effective absorption emissivity depends on the absorption and emission of the cloud; it is parameterized in terms of optical thickness. The effective scattering emissivity depends on the scattering properties of the cloud; it is parameterized in terms of optical thickness and single scattering albedo. The effective reflection emissivity follows the similarity relation as in the near infrared cases. This is parameterized in terms of the similarity parameter and optical thickness, as well as the temperature difference between the cloud and ground.
Institute of Scientific and Technical Information of China (English)
廖敏夫; 段雄英; 邹积岩
2004-01-01
Based on the dynamic dielectric recovery process in the vacuum gaps in series, investigations were made on post-arc insulation state in double and multi-breaks operation in high voltage power system. From the research on the breakdown weak points in high voltage vacuum gaps, their turnout and distribution, some theoretic work were made to set up the models for describing the statistical property of multi-breaks vacuum circuit-breakers' breakdown and post-arc re-strike, which can be used for explaining the mechanism of the improvement in the breaking capacity of multi-breaks units compared with that of single-break ones which have the same equivalent gap length. The advantages of vacuum breakers with multi-breaks are proposed.
Wysokiński, Marcin M; Spałek, Jozef
2014-02-01
We discuss the Hubbard model in an applied magnetic field and analyze the properties of neutral spin-[Formula: see text] fermions within the so-called statistically consistent Gutzwiller approximation. The magnetization curve reproduces in a semiquantitative manner the experimental data for liquid (3)He in the regime of moderate correlations and in the presence of a small number of vacant cells, modeled by a non-half-filled band situation, when a small number of vacancies (∼5%) is introduced in the virtual fcc lattice. We also present the results for the magnetic susceptibility and the specific heat, in which a metamagnetic-like behavior is also singled out in a non-half-filled band case.
... Standards Act and Program MQSA Insights MQSA National Statistics Share Tweet Linkedin Pin it More sharing options ... but should level off with time. Archived Scorecard Statistics 2017 Scorecard Statistics 2016 Scorecard Statistics (Archived) 2015 ...
Kalsia, Mohit; Dondapati, Raja Sekhar; Usurumarti, Preeti Rao
2017-05-01
High Temperature Superconducting (HTS) cables are emerging as an alternative to conventional cables in efficient power transmission. However, these HTS cables require cooling below the critical temperature of superconductors used to transmit larger currents. With the invention of high temperature superconductors whose critical temperatures are up to 134 K (Hg based), it is a great challenge to identify a suitable coolant which can carry away the heating load on the superconductors. In order to accomplish such challenge, an attempt has been made in the present work to propose supercritical Argon (SCAR) as the alternative to cool the HTS cables. Further, a statistical correlation has been developed for the thermophysical properties such as density, viscosity, specific heat and thermal conductivity of SCAR. In addition, the accuracy of developed correlations is established with the help of few statistical parameters and validated with standard database available in the literature. These temperature dependent accurate correlations are useful in predicting the pressure drop and heat transfer behaviour in HTS cables using numerical or computational techniques. In recent times, with the sophistication of computer technology, solving of various complex transport equations along with the turbulence models became popular and hence the developed correlations would benefit the technological community. It is observed that, a decrease in pressure, density and viscosity are found to be decreasing whereas the thermal conductivity and specific heat increase significantly. It can be concluded that higher heat transfer rate and lower pumping power can be achieved with SCAR as coolant in the HTS cables.
Directory of Open Access Journals (Sweden)
Yujun Qiu
2017-01-01
Full Text Available The relationship between cloud and aerosol properties was investigated over two 4° × 4° adjacent regions in the south (R1 and in the north (R2 in eastern China. The CloudSat/CALIPSO data were used to extract the cloud and aerosol profiles properties. The mean value of cloud occurrence probability (COP was the highest in the mixed cloud layer (−40°C~0°C and the lowest in the warm cloud layer (>0°C. The atmospheric humidity was more statistically relevant to COP in the warm cloud layer than aerosol condition. The differences in COP between the two regions in the mixed cloud layer and ice cloud layer (<−40°C had good correlations with those in the aerosol extinction coefficient. A radar reflectivity factor greater than −10 dBZ occurred mainly in warm cloud layers and mixed cloud layers. A high-COP zone appeared in the above-0°C layer with cloud thicknesses of 2-3 km in both regions and in all the four seasons, but the distribution of the zonal layer in R2 was more continuous than that in R1, which was consistent with the higher aerosol optical thickness in R2 than in R1 in the above-0°C layer, indicating a positive correlation between aerosol and cloud probability.
Dubovik, O.; Herman, M.; Holdak, A.; Lapyonok, T.; Tanré, D.; Deuzé, J. L.; Ducos, F.; Sinyuk, A.; Lopatin, A.
2011-05-01
The proposed development is an attempt to enhance aerosol retrieval by emphasizing statistical optimization in inversion of advanced satellite observations. This optimization concept improves retrieval accuracy relying on the knowledge of measurement error distribution. Efficient application of such optimization requires pronounced data redundancy (excess of the measurements number over number of unknowns) that is not common in satellite observations. The POLDER imager on board the PARASOL micro-satellite registers spectral polarimetric characteristics of the reflected atmospheric radiation at up to 16 viewing directions over each observed pixel. The completeness of such observations is notably higher than for most currently operating passive satellite aerosol sensors. This provides an opportunity for profound utilization of statistical optimization principles in satellite data inversion. The proposed retrieval scheme is designed as statistically optimized multi-variable fitting of all available angular observations obtained by the POLDER sensor in the window spectral channels where absorption by gas is minimal. The total number of such observations by PARASOL always exceeds a hundred over each pixel and the statistical optimization concept promises to be efficient even if the algorithm retrieves several tens of aerosol parameters. Based on this idea, the proposed algorithm uses a large number of unknowns and is aimed at retrieval of extended set of parameters affecting measured radiation. The algorithm is designed to retrieve complete aerosol properties globally. Over land, the algorithm retrieves the parameters of underlying surface simultaneously with aerosol. In all situations, the approach is anticipated to achieve a robust retrieval of complete aerosol properties including information about aerosol particle sizes, shape, absorption and composition (refractive index). In order to achieve reliable retrieval from PARASOL observations even over very reflective
Directory of Open Access Journals (Sweden)
O. Dubovik
2011-05-01
Full Text Available The proposed development is an attempt to enhance aerosol retrieval by emphasizing statistical optimization in inversion of advanced satellite observations. This optimization concept improves retrieval accuracy relying on the knowledge of measurement error distribution. Efficient application of such optimization requires pronounced data redundancy (excess of the measurements number over number of unknowns that is not common in satellite observations. The POLDER imager on board the PARASOL micro-satellite registers spectral polarimetric characteristics of the reflected atmospheric radiation at up to 16 viewing directions over each observed pixel. The completeness of such observations is notably higher than for most currently operating passive satellite aerosol sensors. This provides an opportunity for profound utilization of statistical optimization principles in satellite data inversion. The proposed retrieval scheme is designed as statistically optimized multi-variable fitting of all available angular observations obtained by the POLDER sensor in the window spectral channels where absorption by gas is minimal. The total number of such observations by PARASOL always exceeds a hundred over each pixel and the statistical optimization concept promises to be efficient even if the algorithm retrieves several tens of aerosol parameters. Based on this idea, the proposed algorithm uses a large number of unknowns and is aimed at retrieval of extended set of parameters affecting measured radiation.
The algorithm is designed to retrieve complete aerosol properties globally. Over land, the algorithm retrieves the parameters of underlying surface simultaneously with aerosol. In all situations, the approach is anticipated to achieve a robust retrieval of complete aerosol properties including information about aerosol particle sizes, shape, absorption and composition (refractive index. In order to achieve reliable retrieval from PARASOL observations
Directory of Open Access Journals (Sweden)
O. Dubovik
2010-11-01
Full Text Available The proposed development is an attempt to enhance aerosol retrieval by emphasizing statistical optimization in inversion of advanced satellite observations. This optimization concept improves retrieval accuracy relying on the knowledge of measurement error distribution. Efficient application of such optimization requires pronounced data redundancy (excess of the measurements number over number of unknowns that is not common in satellite observations. The POLDER imager on board of the PARASOL micro-satellite registers spectral polarimetric characteristics of the reflected atmospheric radiation at up to 16 viewing directions over each observed pixel. The completeness of such observations is notably higher than for most currently operating passive satellite aerosol sensors. This provides an opportunity for profound utilization of statistical optimization principles in satellite data inversion. The proposed retrieval scheme is designed as statistically optimized multi-variable fitting of the all available angular observations of total and polarized radiances obtained by POLDER sensor in the window spectral channels where absorption by gaseous is minimal. The total number of such observations by PARASOL always exceeds a hundred over each pixel and the statistical optimization concept promises to be efficient even if the algorithm retrieves several tens of aerosol parameters. Based on this idea, the proposed algorithm uses a large number of unknowns and is aimed on retrieval of extended set of parameters affecting measured radiation.
The algorithm is designed to retrieve complete aerosol properties globally. Over land, the algorithm retrieves the parameters of underlying surface simultaneously with aerosol. In all situations, the approach is anticipated to achieve a robust retrieval of complete aerosol properties including information about aerosol particle sizes, shape, absorption and composition (refractive index. In order to achieve
Vallianatos, F.; Karakostas, V.; Papadimitriou, E.
2012-04-01
On 14 August 2003, Lefkada Island (Central Ionian) was affected by an Mw=6.2 earthquake. Due to a dense temporary seismic network that operating immediately after the main shock occurrence, hundreds of aftershocks were recorded and located with high precision whereas relocation of the main shock and early strong aftershocks became also feasible. Thus, the spatio-temporal distribution of aftershocks onto the main and the neighboring fault segments was investigated in detail enabling the recognition of four distinctive seismicity clusters separated by less active patches. The aftershock spatiotemporal properties studied here using the concept of Non-Extensive Statistical Physics (NESP). The cumulative distribution functions of the inter-event times and the inter-event distances are estimated for the data set in each seismicity cluster and the analysis results to a value of the statistical thermodynamic qT and qD parameters for each cluster, where qT varies from 1.15 to 1.47 and qD from 0.5 to 0.77 for the interevent times and distances distributions respectively. These values confirm the complexity and non-additivity of the spatiotemporal evolution of seismicity and the usefulness of NESP in investigating such phenomena. The temporal structure is also discussed using the complementary to NESP approach of superstatistics, which is based on a superposition of ordinary local equilibrium statistical mechanics. The result indicates that the temporal evolution of the Lefkada aftershock sequence in clusters A, B and C governed by very low number of degrees of freedom while D is less organized seismicity structure with a much higher number of degrees of freedom. Acknowledgments. This work was supported in part by the THALES Program of the Ministry of Education of Greece and the European Union in the framework of the project entitled "Integrated understanding of Seismicity, using innovative Methodologies of Fracture mechanics along with Earthquake and non extensive
Energy Technology Data Exchange (ETDEWEB)
Pimentel, Carlos Alberto Rocha [Instituto Tecnologico de Aeronautica, Sao Jose dos Campos, SP (Brazil). Inst. de Engenharia Aeronautica; Hinckel, Jose Nivaldo; Koreeda, Jorge [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Div. de Mecanica Espacial e Controle]. E-mail: carlosal@aer.ita.cta.br; hinckel@sigma.dem.inpe.br
1997-07-01
This work presents the results of an analytical model and a computer program to obtain thermochemical properties of combustion products in a liquid rocket motors, using the method of statistical mechanic to calculation thermodynamic properties of the species. The equations of statistical mechanics and the technique of minimizing of Gibbs free energy are used to calculate the thermochemical functions and the equilibrium chemical composition. These methods are applied to the calculation of equilibrium properties of the combustion products in liquid rocket motors for different propellant pairs, O/F ratios and chamber pressures. The results obtained from this method are compared to those of NASA SP-273. (author)
Gallavotti, Giovanni
2011-01-01
C. Cercignani: A sketch of the theory of the Boltzmann equation.- O.E. Lanford: Qualitative and statistical theory of dissipative systems.- E.H. Lieb: many particle Coulomb systems.- B. Tirozzi: Report on renormalization group.- A. Wehrl: Basic properties of entropy in quantum mechanics.
Prinos, Scott T.; Dixon, Joann F.
2016-02-25
Statistical analyses and maps representing mean, high, and low water-level conditions in the surface water and groundwater of Miami-Dade County were made by the U.S. Geological Survey, in cooperation with the Miami-Dade County Department of Regulatory and Economic Resources, to help inform decisions necessary for urban planning and development. Sixteen maps were created that show contours of (1) the mean of daily water levels at each site during October and May for the 2000–2009 water years; (2) the 25th, 50th, and 75th percentiles of the daily water levels at each site during October and May and for all months during 2000–2009; and (3) the differences between mean October and May water levels, as well as the differences in the percentiles of water levels for all months, between 1990–1999 and 2000–2009. The 80th, 90th, and 96th percentiles of the annual maximums of daily groundwater levels during 1974–2009 (a 35-year period) were computed to provide an indication of unusually high groundwater-level conditions. These maps and statistics provide a generalized understanding of the variations of water levels in the aquifer, rather than a survey of concurrent water levels. Water-level measurements from 473 sites in Miami-Dade County and surrounding counties were analyzed to generate statistical analyses. The monitored water levels included surface-water levels in canals and wetland areas and groundwater levels in the Biscayne aquifer.
Relationships Between Complex Core Level Spectra and Materials Properties
Energy Technology Data Exchange (ETDEWEB)
Nelin, Constance J.; Bagus, Paul S.; Ilton, Eugene S.; Chambers, Scott A.; Kuhlenbeck, Helmut; Freund, Hans-Joachim
2010-12-01
The XPS of many oxides are quite complex and there may be several peaks of significant intensity for each subshell. These peaks arise from many-electron effects, which normally are treated with configuration interaction (CI) wavefunctions where static correlation effects are taken into account. It is common to use semiempirical methods to determine the matrix elements of the CI Hamiltonian and there are few rigorous CI calculations where parameters are not adjusted to fit experiment. In contrast, we present, in the present work, theoretical XPS spectra obtained with rigorous CI wavefunctions for CeO2 where the XPS are especially complex; several different core levels are studied. This study uses an embedded CeO8 cluster model to represent bulk CeO2 and the relativistic CI wavefunctions are determined using four-component spinors from Dirac-Fock calculations. In particular, we examine the importance of interatomic many-body effects where there is a transfer of electrons from occupied oxygen 2p orbitals into empty cation orbitals as it is common to ascribe the complex XPS to this effect. We also contrast the importance of many-body charge-transfer effects for the isoelectronic cations of Ce4+ and La3+. The long-range goal of this work is to relate the XPS features to the nature of the chemical bonding in CeO2 and we describe our progress toward this goal.
Hassad, Rossi A.
2009-01-01
This study examined the teaching practices of 227 college instructors of introductory statistics (from the health and behavioral sciences). Using primarily multidimensional scaling (MDS) techniques, a two-dimensional, 10-item teaching practice scale, TISS (Teaching of Introductory Statistics Scale), was developed and validated. The two dimensions…
Gofford, Jason; Tombesi, Francesco; Braito, Valentina; Turner, T Jane; Miller, Lance; Cappi, Massimo
2012-01-01
We present the results of a new spectroscopic study of Fe K-band absorption in Active Galactic Nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically driven blind search for Fe XXV Hea and/or Fe XXVI Lyb absorption lines in a large sample of 51 type 1.0-1.9 AGN. Through extensive Monte Carlo simulations we find statistically significant absorption is detected at E>6.7 keV in 20/51 sources at the P(MC)>95% level, which corresponds to ~40% of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available XIS detectors which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe XXV Hea and Fe XXVI Lyb at a common velocity shift. From xstar fitting the mean column density and ionisation parameter for the Fe K absorption components are log(NH/cm^{-2})~23 and log(xi/erg cm s^{-1})~4.5, ...
Hoshyaripour, G.; Brasseur, G.; Andrade, M. F.; Gavidia-Calderón, M.; Bouarar, I.; Ynoue, R. Y.
2016-11-01
Two state-of-the-art models (deterministic: Weather Research and Forecast model with Chemistry (WRF-Chem) and statistic: Artificial Neural Networks: (ANN)) are implemented to predict the ground-level ozone concentration in São Paulo (SP), Brazil. Two domains are set up for WRF-Chem simulations: a coarse domain (with 50 km horizontal resolution) including whole South America (D1) and a nested domain (with horizontal resolution of 10 km) including South Eastern Brazil (D2). To evaluate the spatial distribution of the chemical species, model results are compared to the Measurements of Pollution in The Troposphere (MOPITT) data, showing that the model satisfactorily predicts the CO concentrations in both D1 and D2. The model also reproduces the measurements made at three air quality monitoring stations in SP with the correlation coefficients of 0.74, 0.70, and 0.77 for O3 and 0.51, 0.48, and 0.57 for NOx. The input selection for ANN model is carried out using Forward Selection (FS) method. FS-ANN is then trained and validated using the data from two air quality monitoring stations, showing correlation coefficients of 0.84 and 0.75 for daily mean and 0.64 and 0.67 for daily peak ozone during the test stage. Then, both WRF-Chem and FS-ANN are deployed to forecast the daily mean and peak concentrations of ozone in two stations during 5-20 August 2012. Results show that WRF-Chem preforms better in predicting mean and peak ozone concentrations as well as in conducting mechanistic and sensitivity analysis. FS-ANN is only advantageous in predicting mean daily ozone concentrations considering its significantly lower computational costs and ease of development and implementation, compared to that of WRF-Chem.
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Kalsia, Mohit [School of Mechanical Engineering, Lovely Professional University, Phagwara, 144 401 (India); Dondapati, Raja Sekhar, E-mail: drsekhar@ieee.org [School of Mechanical Engineering, Lovely Professional University, Phagwara, 144 401 (India); Usurumarti, Preeti Rao [Department of Mechanical Engineering, PVK Institute of Technology, Anantpur, 515 001 (India)
2017-05-15
Highlights: • The developed correlations can be integrated into thermohydraulic analysis of HTS cables. • This work also explains the phenomenon of flow with less pumping power and maximum heat transfer in HTS cables. • Pumping power required to circulate the SCAR for cooling of HTS cables would be significantly lower. • For Hg-based high temperature superconductors (T{sub c} > 134 K), SCAR found to be a suitable coolant. - Abstract: High Temperature Superconducting (HTS) cables are emerging as an alternative to conventional cables in efficient power transmission. However, these HTS cables require cooling below the critical temperature of superconductors used to transmit larger currents. With the invention of high temperature superconductors whose critical temperatures are up to 134 K (Hg based), it is a great challenge to identify a suitable coolant which can carry away the heating load on the superconductors. In order to accomplish such challenge, an attempt has been made in the present work to propose supercritical Argon (SCAR) as the alternative to cool the HTS cables. Further, a statistical correlation has been developed for the thermophysical properties such as density, viscosity, specific heat and thermal conductivity of SCAR. In addition, the accuracy of developed correlations is established with the help of few statistical parameters and validated with standard database available in the literature. These temperature dependent accurate correlations are useful in predicting the pressure drop and heat transfer behaviour in HTS cables using numerical or computational techniques. In recent times, with the sophistication of computer technology, solving of various complex transport equations along with the turbulence models became popular and hence the developed correlations would benefit the technological community. It is observed that, a decrease in pressure, density and viscosity are found to be decreasing whereas the thermal conductivity and specific
Directory of Open Access Journals (Sweden)
Batac Rene C.
2016-02-01
Full Text Available The aftershock records of the magnitude 7.1 earthquake that hit the island of Bohol in central Philippines on 15 October 2013 is investigated in the light of previous results for the Philippines using historical earthquakes. Statistics of interevent distances and interevent times between successive aftershocks recorded for the whole month of October 2013 show marked differences from those of historical earthquakes from two Philippine catalogues of varying periods and completeness levels. In particular, the distributions closely follow only the regimes of the historical distributions that were previously attributed to the strong spatio-temporal correlations. The results therefore suggest that these correlated regimes which emerged naturally from the analyses are strongly dominated by the clustering of aftershock events.
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-12-01
The US DOE has presented plans for processing liquid low-level wastes (LLLW) located at Oak Ridge National Laboratory (ORNL) in the LLLW tank system. These wastes are among the most hazardous on the Oak Ridge reservation and exhibit both RCRA toxic and radiological hazards. The Tennessee Department of Health and Environment has mandated that the processing of these wastes must begin by the year 2002 and the the goal should be permanent disposal at a site off the Oak Ridge Reservation. To meet this schedule, DOE will solicit bids from various private sector companies for the construction of a processing facility on land located near the ORNL Melton Valley Storage Tanks to be operated by the private sector on a contract basis. This report will support the Request for Proposal process and will give potential vendors information about the wastes contained in the ORNL tank farm system. The report consolidates current data about the properties and composition of these wastes and presents methods to calculate the error bounds of the data in the best technically defensible manner possible. The report includes information for only the tank waste that is to be included in the request for proposal.
Miwa, Yoshiro
2011-01-01
The Ministry of Finance's "Corporate Enterprise Quarterly Statistics" (Hojin kigyo tokei kiho) is the only statistical source of well-balanced information about the financing behavior of Japanese firms. Indeed, there are few comparable sources available anywhere in the world. Using this firm-level data set from 1994 to 2009, the author investigates the financing behavior of Japanese firms with over \\10 million in paid-in capital. The conclusions contrast sharply with the conventional wisdom. ...
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Malapaka, Shiva Kumar; Mueller, Wolf-Christian [Max-Planck Institute for Plasma Physics, Boltzmannstrasse 2, D-85748 Garching bei Muenchen (Germany)
2013-09-01
Statistical properties of the Sun's photospheric turbulent magnetic field, especially those of the active regions (ARs), have been studied using the line-of-sight data from magnetograms taken by the Solar and Heliospheric Observatory and several other instruments. This includes structure functions and their exponents, flatness curves, and correlation functions. In these works, the dependence of structure function exponents ({zeta}{sub p}) of the order of the structure functions (p) was modeled using a non-intermittent K41 model. It is now well known that the ARs are highly turbulent and are associated with strong intermittent events. In this paper, we compare some of the observations from Abramenko et al. with the log-Poisson model used for modeling intermittent MHD turbulent flows. Next, we analyze the structure function data obtained from the direct numerical simulations (DNS) of homogeneous, incompressible 3D-MHD turbulence in three cases: sustained by forcing, freely decaying, and a flow initially driven and later allowed to decay (case 3). The respective DNS replicate the properties seen in the plots of {zeta}{sub p} against p of ARs. We also reproduce the trends and changes observed in intermittency in flatness and correlation functions of ARs. It is suggested from this analysis that an AR in the onset phase of a flare can be treated as a forced 3D-MHD turbulent system in its simplest form and that the flaring stage is representative of decaying 3D-MHD turbulence. It is also inferred that significant changes in intermittency from the initial onset phase of a flare to its final peak flaring phase are related to the time taken by the system to reach the initial onset phase.
Directory of Open Access Journals (Sweden)
Rives, V.
2006-03-01
Full Text Available The suitability of granite conservation treatments (consolidation and/or water-repellency wide/y used to protect heritage structures was evaluated on the basis of the changes occurring in the intrinsic characteristics of the stone (imbibition capacity open porosity total water-accessible porosity water vapour permeability and capillar absorption coefficient. A statistical analysis conducted of the values obtained for these properties/ which showed differences in fluid flow through the rocks/ found that the application of consolidants followed by water repellency treatment was more effective than either procedure alone, substantially enhancing the properties of the stone from the standpoint of its use as a construction material.La adecuación de tratamientos de conservación (consolidación y/o hidrofugación realizados sobre granitos ampliamente utilizados en el patrimonio cultura se evaluó por los cambios experimentados en las características intrínsecas de estas rocas (capacidad de imbibición/ porosidad abierta/ porosidad total accesible al agua/ permeabilidad al vapor de agua y coeficiente de absorción capilar. Se realizó un análisis estadístico de los valores obtenidos de estas propiedades que muestra diferentes capacidades para el transporte de fluidos a través de las rocas/ indicando que el tratamiento con consolidantes y posterior aplicación de hidrofugantes tiene mayor efecto que los dos aplicados independientemente y mejora notablemente sus propiedades como material de construcción.
Mandl, Franz
1988-01-01
The Manchester Physics Series General Editors: D. J. Sandiford; F. Mandl; A. C. Phillips Department of Physics and Astronomy, University of Manchester Properties of Matter B. H. Flowers and E. Mendoza Optics Second Edition F. G. Smith and J. H. Thomson Statistical Physics Second Edition E. Mandl Electromagnetism Second Edition I. S. Grant and W. R. Phillips Statistics R. J. Barlow Solid State Physics Second Edition J. R. Hook and H. E. Hall Quantum Mechanics F. Mandl Particle Physics Second Edition B. R. Martin and G. Shaw The Physics of Stars Second Edition A. C. Phillips Computing for Scient
Xia, Jun-Qing; Wang, Guo-Jian; Tian, Shu-Xun; Li, Zheng-Xiang; Cao, Shuo; Zhu, Zong-Hong
2016-01-01
In this paper we use a recently compiled data set, which comprises 118 galactic-scale strong gravitational lensing (SGL) systems to constrain the statistic property of SGL system, as well as the curvature of universe without assuming any fiducial cosmological model. Based on the singular isothermal ellipsoid (SIE) model of SGL system, we obtain that the constrained curvature parameter $\\Omega_{\\rm k}$ is close to zero from the SGL data, which is consistent with the latest result of planck measurement. More interestingly, we find that the parameter $f$ in the SIE model is strongly correlated with the curvature $\\Omega_{\\rm k}$. Neglecting this correlation in the analysis will significantly overestimate the constraining power of SGL data on the curvature. Furthermore, the obtained constraint on $f$ is different from previous results: $f=1.105\\pm0.030$ ($68\\%$ C.L.), which means that the standard singular isothermal sphere (SIS) model ($f=1$) is disfavored by the current SGL data at more than $3\\sigma$ confidenc...
Energy Technology Data Exchange (ETDEWEB)
Rossi, L [Department of Physics, University of Bologna, Bologna 40126 (Italy); Universite du Sud Toulon-Var, 83957 La Garde Cedex (France); Turchetti, G [Department of Physics, University of Bologna, Bologna 40126 (Italy); Vaienti, S [Universite du Sud Toulon-Var, 83957 La Garde Cedex (France) and UMR-CPT 6207, Marseille 13288 (France); Universites d' Aix-Marseille I, II and Federation de Recherche des Unites de Mathematique de Marseille, Marseille (France)
2005-01-01
Poincare recurrences seem able to capture some of the fundamental properties of dynamical systems. In fact, the asymptotic distribution of Poincare recurrences is exponential for a wide class of mixing systems, even if they are not uniformly hyperbolic. On the other hand, we found strong numerical evidences that for integrable systems such distribution follows an algebraic decay law, showing this behavior for a skew integrable map on a cylinder. For a mixed system, that is a system composed by two or more invariant regions, we proved that the statistics of Poincare recurrences of points at the boundaries is a linear combination of the spectra characteristic of the various components. We think that these results could allow to understand the behavior of area-preserving maps in the mixed regions where integrable structures and chaotic components coexist. In this respect, the intense numerical studies performed by several authors suggest that in the thin stochastic layer surrounding a chain of islands the decay of Poincare recurrences could follow a power law due to the sticking phenomenon, which is believed to be responsible for the anomalous diffusion modeled by Levy like processes. Furthermore, such a mixture of exponential and power law decays has been observed in a model of stationary flow with hexagonal symmetry, when the transport is anomalous. Some preliminary investigations show that, at least for the skew and for the mixing maps, the results obtained about the first return times spectra also hold for the successive Poincare recurrences.