Benford's Law and Continuous Dependent Random Variables
Becker, Thealexa; Miller, Steven J; Ronan, Ryan; Strauch, Frederick W
2011-01-01
Many systems exhibit a digit bias. For example, the first digit base 10 of the Fibonacci numbers, or of $2^n$, equals 1 not 10% or 11% of the time, as one would expect if all digits were equally likely, but about 30% of the time. This phenomenon, known as Benford's Law, has many applications, ranging from detecting tax fraud for the IRS to analyzing round-off errors in computer science. The central question is determining which data sets follow Benford's law. Inspired by natural processes such as particle decay, our work examines models for the decomposition of conserved quantities. We prove that in many instances the distribution of lengths of the resulting pieces converges to Benford behavior as the number of divisions grow. The main difficulty is that the resulting random variables are dependent, which we handle by a careful analysis of the dependencies and tools from Fourier analysis to obtain quantified convergence rates.
LARGE DEVIATIONS AND MODERATE DEVIATIONS FOR SUMS OF NEGATIVELY DEPENDENT RANDOM VARIABLES
Liu Li; Wan Chenggao; Feng Yanqin
2011-01-01
In this article, we obtain the large deviations and moderate deviations for negatively dependent (ND) and non-identically distributed random variables defined on (-∞, +∞). The results show that for some non-identical random variables, precise large deviations and moderate deviations remain insensitive to negative dependence structure.
The functional central limit theorem for strong near-epoch dependent random variables
QIU Jin; LIN Zhengyan
2004-01-01
The functional central limit theorem for strong near-epoch dependent sequences of random variables is proved.The conditions given improve on previous results in the literature concerning dependence and heterogeneity.
On an asymptotic distribution of dependent random variables on a 3-dimensional lattice.
Harvey, Danielle J; Weng, Qian; Beckett, Laurel A
2010-06-15
We define conditions under which sums of dependent spatial data will be approximately normally distributed. A theorem on the asymptotic distribution of a sum of dependent random variables defined on a 3-dimensional lattice is presented. Examples are also presented.
无
2010-01-01
This paper studies the moderate deviations of real-valued extended negatively dependent(END) random variables with consistently varying tails.The moderate deviations of partial sums are first given.The results are then used to establish the necessary and sufficient conditions for the moderate deviations of random sums under certain circumstances.
A CENTRAL LIMIT THEOREM FOR STRONG NEAR-EPOCH DEPENDENT RANDOM VARIABLES
LIN ZHENGYAN; QIU JIN
2004-01-01
In this paper, a central limit theorem for strong near-epoch dependent sequences of random variables introduced in [9] is showed. Under the same moments condition,the authors essentially weaken the "size" requirement mentioned in other papers about near epoch dependence.
On an asymptotic distribution of dependent random variables on a 3-dimensional lattice✩
Harvey, Danielle J.; Weng, Qian; Beckett, Laurel A.
2010-01-01
We define conditions under which sums of dependent spatial data will be approximately normally distributed. A theorem on the asymptotic distribution of a sum of dependent random variables defined on a 3-dimensional lattice is presented. Examples are also presented. PMID:20436940
Weak laws of large numbers for arrays of rowwise negatively dependent random variables
R. L. Taylor
2001-01-01
Full Text Available Weak laws of large numbers for arrays of rowwise negatively dependent random variables are obtained in this paper. The more general hypothesis of negative dependence relaxes the usual assumption of independence. The moment conditions are similar to previous results, and the stochastic bounded condition also provides a generalization of the usual distributional assumptions.
Asymptotic Results for Tail Probabilities of Sums of Dependent and Heavy-Tailed Random Variables
Kam Chuen YUEN; Chuancun YIN
2012-01-01
Abstract Let X1,X2,...be a sequence of dependent and heavy-tailed random variables with distributions F1,F2,…. on (-∞,∞),and let т be a nonnegative integer-valued random variable independent of the sequence {Xk,k≥ 1}.In this framework,the asymptotic behavior of the tail probabilities of the quantities Sn =n∑k=1 Xk and S(n) =max1≤k≤n Sk for n ＞ 1,and their randomized versions Sт and S(т) are studied.Some applications to the risk theory are presented.
Tail dependence of random variables from ARCH and heavy tailed bilinear models
潘家柱
2002-01-01
Discussed in this paper is the dependent structure in the tails of distributions of random variables from some heavy-tailed stationary nonlinear time series. One class of models discussed is the first-order autoregressive conditional heteroscedastic (ARCH) process introduced by Engle (1982). The other class is the simple first-order bilinear models driven by heavy-tailed innovations. We give some explicit formulas for the asymptotic values of conditional probabilities used for measuring the tail dependence between two random variables from these models. Our results have significant meanings in finance.
An edgeworth expansion for a sum of M-Dependent random variables
Wan Soo Rhee
1985-01-01
Full Text Available Given a sequence X1,X2,…,Xn of m-dependent random variables with moments of order 3+α (0<α≦1, we give an Edgeworth expansion of the distribution of Sσ−1(S=X1+X2+…+Xn, σ2=ES2 under the assumption that E[exp(it Sσ1] is small away from the origin. The result is of the best possible order.
Conditional acceptability of random variables
Tasos C Christofides
2016-06-01
Full Text Available Abstract Acceptable random variables introduced by Giuliano Antonini et al. (J. Math. Anal. Appl. 338:1188-1203, 2008 form a class of dependent random variables that contains negatively dependent random variables as a particular case. The concept of acceptability has been studied by authors under various versions of the definition, such as extended acceptability or wide acceptability. In this paper, we combine the concept of acceptability with the concept of conditioning, which has been the subject of current research activity. For conditionally acceptable random variables, we provide a number of probability inequalities that can be used to obtain asymptotic results.
J.L. Geluk (Jaap); C.G. de Vries (Casper)
2004-01-01
textabstractAsymptotic tail probabilities for bivariate linear combinations of subexponential random variables are given. These results are applied to explain the joint movements of the stocks of reinsurers. Portfolio investment and retrocession practices in the reinsurance industry, for reasons of
Matricially free random variables
Lenczewski, Romuald
2008-01-01
We show that the operatorial framework developed by Voiculescu for free random variables can be extended to arrays of random variables whose multiplication imitates matricial multiplication. The associated notion of independence, called matricial freeness, can be viewed as a generalization of both freeness and monotone independence. At the same time, the sums of matricially free random variables, called random pseudomatrices, are closely related to Gaussian random matrices. The main results presented in this paper concern the standard and tracial central limit theorems for random pseudomatrices and the corresponding limit distributions which can be viewed as matricial generalizations of semicirle laws.
A functional limit theorem for partial sums of dependent random variables with infinite variance
Basrak, Bojan; Segers, Johan
2010-01-01
Under an appropriate regular variation condition, the affinely normalized partial sums of a sequence of independent and identically distributed random variables converges weakly to a non-Gaussian stable random variable. A functional version of this is known to be true as well, the limit process being a stable L\\'evy process. The main result in the paper is that for a stationary, regularly varying sequence for which clusters of high-threshold excesses can be broken down into asymptotically independent blocks, the properly centered partial sum process still converges to a stable L\\'evy process. Due to clustering, the L\\'evy triple of the limit process can be different from the one in the independent case. The convergence takes place in the space of c\\`adl\\`ag functions endowed with Skorohod's $M_1$ topology, the more usual $J_1$ topology being inappropriate as the partial sum processes may exhibit rapid successions of jumps within temporal clusters of large values, collapsing in the limit to a single jump. The ...
Penzlin AI
2015-10-01
Full Text Available Ana Isabel Penzlin,1 Timo Siepmann,2 Ben Min-Woo Illigens,3 Kerstin Weidner,4 Martin Siepmann4 1Institute of Clinical Pharmacology, 2Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Saxony, Germany; 3Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; 4Department of Psychotherapy and Psychosomatic Medicine, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Saxony, Germany Background and objective: In patients with alcohol dependence, ethyl-toxic damage of vasomotor and cardiac autonomic nerve fibers leads to autonomic imbalance with neurovascular and cardiac dysfunction, the latter resulting in reduced heart rate variability (HRV. Autonomic imbalance is linked to increased craving and cardiovascular mortality. In this study, we sought to assess the effects of HRV biofeedback training on HRV, vasomotor function, craving, and anxiety. Methods: We conducted a randomized controlled study in 48 patients (14 females, ages 25–59 years undergoing inpatient rehabilitation treatment. In the treatment group, patients (n=24 attended six sessions of HRV biofeedback over 2 weeks in addition to standard rehabilitative care, whereas, in the control group, subjects received standard care only. Psychometric testing for craving (Obsessive Compulsive Drinking Scale, anxiety (Symptom Checklist-90-Revised, HRV assessment using coefficient of variation of R-R intervals (CVNN analysis, and vasomotor function assessment using laser Doppler flowmetry were performed at baseline, immediately after completion of treatment or control period, and 3 and 6 weeks afterward (follow-ups 1 and 2. Results: Psychometric testing showed decreased craving in the biofeedback group immediately postintervention (OCDS scores: 8.6±7.9 post-biofeedback versus 13.7±11.0 baseline [mean ± standard deviation], P<0.05, whereas craving was unchanged at
Ming He
2015-11-01
Full Text Available We propose a random effects panel data model with both spatially correlated error components and spatially lagged dependent variables. We focus on diagnostic testing procedures and derive Lagrange multiplier (LM test statistics for a variety of hypotheses within this model. We first construct the joint LM test for both the individual random effects and the two spatial effects (spatial error correlation and spatial lag dependence. We then provide LM tests for the individual random effects and for the two spatial effects separately. In addition, in order to guard against local model misspecification, we derive locally adjusted (robust LM tests based on the Bera and Yoon principle (Bera and Yoon, 1993. We conduct a small Monte Carlo simulation to show the good finite sample performances of these LM test statistics and revisit the cigarette demand example in Baltagi and Levin (1992 to illustrate our testing procedures.
Functional limit theorem for moving average processes generated by dependent random variables
无
2006-01-01
Let {Xt,t≥1} be a moving average process defined byXt = ∞∑j=0bjξt-j , where {bj,j≥0} is a sequence of real numbers and { ξt, ∞＜ t ＜∞ } is a doubly infinite sequence of strictly stationary φ- mixing random variables. Under conditions on { bj, j ≥0 }which entail that { Xt, t ≥ 1 } is either a long memory process or a linear process, we study asymptotics of Sn ( s ) = [ns]∑t=1 Xt (properly normalized). When { Xt, t≥1 } is a long memory process, we establish a functional limit theorem. When { Xt, t≥1 } is a linear process, we not only obtain the multi-dimensional weak convergence for { Xt, t≥1 }, but also weaken the moment condition on { ξt, - ∞＜ t ＜∞ } and the restriction on { bj,j≥0}. Finally, we give some applications of our results.
Guillaume Marrelec
Full Text Available The use of mutual information as a similarity measure in agglomerative hierarchical clustering (AHC raises an important issue: some correction needs to be applied for the dimensionality of variables. In this work, we formulate the decision of merging dependent multivariate normal variables in an AHC procedure as a Bayesian model comparison. We found that the Bayesian formulation naturally shrinks the empirical covariance matrix towards a matrix set a priori (e.g., the identity, provides an automated stopping rule, and corrects for dimensionality using a term that scales up the measure as a function of the dimensionality of the variables. Also, the resulting log Bayes factor is asymptotically proportional to the plug-in estimate of mutual information, with an additive correction for dimensionality in agreement with the Bayesian information criterion. We investigated the behavior of these Bayesian alternatives (in exact and asymptotic forms to mutual information on simulated and real data. An encouraging result was first derived on simulations: the hierarchical clustering based on the log Bayes factor outperformed off-the-shelf clustering techniques as well as raw and normalized mutual information in terms of classification accuracy. On a toy example, we found that the Bayesian approaches led to results that were similar to those of mutual information clustering techniques, with the advantage of an automated thresholding. On real functional magnetic resonance imaging (fMRI datasets measuring brain activity, it identified clusters consistent with the established outcome of standard procedures. On this application, normalized mutual information had a highly atypical behavior, in the sense that it systematically favored very large clusters. These initial experiments suggest that the proposed Bayesian alternatives to mutual information are a useful new tool for hierarchical clustering.
Anwer Khurshid
2012-07-01
Full Text Available Normal 0 false false false EN-US X-NONE X-NONE In this paper, it is shown that a complex multivariate random variable is a complex multivariate normal random variable of dimensionality if and only if all nondegenerate complex linear combinations of have a complex univariate normal distribution. The characteristic function of has been derived, and simpler forms of some theorems have been given using this characterization theorem without assuming that the variance-covariance matrix of the vector is Hermitian positive definite. Marginal distributions of have been given. In addition, a complex multivariate t-distribution has been defined and the density derived. A characterization of the complex multivariate t-distribution is given. A few possible uses of this distribution have been suggested.
Strong Decomposition of Random Variables
Hoffmann-Jørgensen, Jørgen; Kagan, Abram M.; Pitt, Loren D.;
2007-01-01
A random variable X is stongly decomposable if X=Y+Z where Y=Φ(X) and Z=X-Φ(X) are independent non-degenerated random variables (called the components). It is shown that at least one of the components is singular, and we derive a necessary and sufficient condition for strong decomposability...... of a discrete random variable....
WEAK UNCORRELATEDNESS OF RANDOM VARIABLES
Sofiya Ostrovska
2006-01-01
New measures of independence for n random variables, based on their moments, are studied. A scale of degrees of independence for random variables which starts with uncorrelatedness (for n = 2) and finishes at independence is constructed. The scale provides a countable linearly ordered set of measures of independence.
Qinghui Du
2014-01-01
Full Text Available We consider semi-implicit Euler methods for stochastic age-dependent capital system with variable delays and random jump magnitudes, and investigate the convergence of the numerical approximation. It is proved that the numerical approximate solutions converge to the analytical solutions in the mean-square sense under given conditions.
Complete Convergence for Weighted Sums of WOD Random Variables
ZHANG Ying; ZHANG Yu; SHEN Ai-ting
2016-01-01
In this article, we study the complete convergence for weighted sums of widely orthant dependent random variables. By using the exponential probability inequality, we establish a complete convergence result for weighted sums of widely orthant dependent ran-dom variables under mild conditions of weights and moments. The result obtained in the paper generalizes the corresponding ones for independent random variables and negatively dependent random variables.
RANDOM VARIABLE WITH FUZZY PROBABILITY
吕恩琳; 钟佑明
2003-01-01
Mathematic description about the second kind fuzzy random variable namely the random variable with crisp event-fuzzy probability was studied. Based on the interval probability and using the fuzzy resolution theorem, the feasible condition about a probability fuzzy number set was given, go a step further the definition arid characters of random variable with fuzzy probability ( RVFP ) and the fuzzy distribution function and fuzzy probability distribution sequence of the RVFP were put forward. The fuzzy probability resolution theorem with the closing operation of fuzzy probability was given and proved. The definition and characters of mathematical expectation and variance of the RVFP were studied also. All mathematic description about the RVFP has the closing operation for fuzzy probability, as a result, the foundation of perfecting fuzzy probability operation method is laid.
Andersen, Andreas; Rieckmann, Andreas
2016-01-01
In this article, we illustrate how to use mi impute chained with intreg to fit an analysis of covariance analysis of censored and nondetectable immunological concentrations measured in a randomized pretest–posttest design....
Ordered random variables theory and applications
Shahbaz, Muhammad Qaiser; Hanif Shahbaz, Saman; Al-Zahrani, Bander M
2016-01-01
Ordered Random Variables have attracted several authors. The basic building block of Ordered Random Variables is Order Statistics which has several applications in extreme value theory and ordered estimation. The general model for ordered random variables, known as Generalized Order Statistics has been introduced relatively recently by Kamps (1995).
ZHENG Lu-lu; XU Chen; HUANG Xu-feng; WANG Xue-jun
2014-01-01
A general result on the strong convergence rate and complete convergence for arrays of rowwise extended negatively dependent random variables is established. As ap-plications, some well-known results on negatively dependent random variables can be easily extended to the case of arrays of rowwise extended negatively dependent random variables.
Asymptotics for Associated Random Variables
Oliveira, Paulo Eduardo
2012-01-01
The book concerns the notion of association in probability and statistics. Association and some other positive dependence notions were introduced in 1966 and 1967 but received little attention from the probabilistic and statistics community. The interest in these dependence notions increased in the last 15 to 20 years, and many asymptotic results were proved and improved. Despite this increased interest, characterizations and results remained essentially scattered in the literature published in different journals. The goal of this book is to bring together the bulk of these results, presenting
Random Effect and Latent Variable Model Selection
Dunson, David B
2008-01-01
Presents various methods for accommodating model uncertainty in random effects and latent variable models. This book focuses on frequentist likelihood ratio and score tests for zero variance components. It also focuses on Bayesian methods for random effects selection in linear mixed effects and generalized linear mixed models
Reduction of the Random Variables of the Turbulent Wind Field
Sichani, Mahdi Teimouri; Nielsen, Søren R.K.
2012-01-01
Applicability of the Probability Density Evolution Method (PDEM) for realizing evolution of the probability density for the wind turbines has rather strict bounds on the basic number of the random variables involved in the model. The efficiency of most of the Advanced Monte Carlo (AMC) methods, i.......e. Importance Sampling (IS) or Subset Simulation (SS), will be deteriorated on problems with many random variables. The problem with PDEM is that a multidimensional integral has to be carried out over the space defined by the random variables of the system. The numerical procedure requires discretization...... of the integral domain; this becomes increasingly difficult as the dimensions of the integral domain increase. On the other hand efficiency of the AMC methods is closely dependent on the design points of the problem. Presence of many random variables may increase the number of the design points, hence affects...
Probability Inequalities for Extended Negatively Dep endent Random Variables and Their Applications
TANG Xiao-feng
2014-01-01
Some probability inequalities are established for extended negatively dependent (END) random variables. The inequalities extend some corresponding ones for negatively associated random variables and negatively orthant dependent random variables. By using these probability inequalities, we further study the complete convergence for END random variables. We also obtain the convergence rate O(n−1/2 ln1/2 n) for the strong law of large numbers, which generalizes and improves the corresponding ones for some known results.
LARGE DEVIATIONS AND MODERATE DEVIATIONS FOR m-NEGATIVELY ASSOCIATED RANDOM VARIABLES
Hu Yijun; Ming Ruixing; Yang Wenquan
2007-01-01
M-negatively associated random variables, which generalizes the classical one of negatively associated random variables and includes m-dependent sequences as its particular case, are introduced and studied. Large deviation principles and moderate deviation upper bounds for stationary m-negatively associated random variables are proved.Kolmogorov-type and Marcinkiewicz-type strong laws of large numbers as well as the three series theorem for m-negatively associated random variables are also given.
The Ziggurat Method for Generating Random Variables
George Marsaglia
2000-10-01
Full Text Available We provide a new version of our ziggurat method for generating a random variable from a given decreasing density. It is faster and simpler than the original, and will produce, for example, normal or exponential variates at the rate of 15 million per second with a C version on a 400MHz PC. It uses two tables, integers ki, and reals wi. Some 99% of the time, the required x is produced by: Generate a random 32-bit integer j and let i be the index formed from the rightmost 8 bits of j. If j < k, return x = j x wi. We illustrate with C code that provides for inline generation of both normal and exponential variables, with a short procedure for settting up the necessary tables.
Fast Generation of Discrete Random Variables
George Marsaglia
2004-07-01
Full Text Available We describe two methods and provide C programs for generating discrete random variables with functions that are simple and fast, averaging ten times as fast as published methods and more than five times as fast as the fastest of those. We provide general procedures for implementing the two methods, as well as specific procedures for three of the most important discrete distributions: Poisson, binomial and hypergeometric.
Random forest automated supervised classification of Hipparcos periodic variable stars
Dubath, P; Süveges, M; Blomme, J; López, M; Sarro, L M; De Ridder, J; Cuypers, J; Guy, L; Lecoeur, I; Nienartowicz, K; Jan, A; Beck, M; Mowlavi, N; De Cat, P; Lebzelter, T; Eyer, L
2011-01-01
We present an evaluation of the performance of an automated classification of the Hipparcos periodic variable stars into 26 types. The sub-sample with the most reliable variability types available in the literature is used to train supervised algorithms to characterize the type dependencies on a number of attributes. The most useful attributes evaluated with the random forest methodology include, in decreasing order of importance, the period, the amplitude, the V-I colour index, the absolute magnitude, the residual around the folded light-curve model, the magnitude distribution skewness and the amplitude of the second harmonic of the Fourier series model relative to that of the fundamental frequency. Random forests and a multi-stage scheme involving Bayesian network and Gaussian mixture methods lead to statistically equivalent results. In standard 10-fold cross-validation experiments, the rate of correct classification is between 90 and 100%, depending on the variability type. The main mis-classification case...
Lr Convergence for Arrays of Rowwise Negatively Sup eradditive Dep endent Random Variables
ZHU Hua-yan; SHEN Ai-ting; ZHANG Ying
2016-01-01
Let {Xnk, k≥1, n≥1} be an array of rowwise negatively superadditive depen-dent random variables and {an, n ≥ 1} be a sequence of positive real numbers such that an ↑ ∞. Under some suitable conditions, Lr convergence of a1n 1max≤j≤n ied. The results obtained in this paper generalize and improve some corresponding ones for negatively associated random variables and independent random variables. fl fl fl fl jP k=1 Xnk fl fl flfl is stud-ied. The results obtained in this paper generalize and improve some corresponding ones for negatively associated random variables and independent random variables.
Random forest automated supervised classification of Hipparcos periodic variable stars
Dubath, P.; Rimoldini, L.; Süveges, M.; Blomme, J.; López, M.; Sarro, L. M.; De Ridder, J.; Cuypers, J.; Guy, L.; Lecoeur, I.; Nienartowicz, K.; Jan, A.; Beck, M.; Mowlavi, N.; De Cat, P.; Lebzelter, T.; Eyer, L.
2011-07-01
We present an evaluation of the performance of an automated classification of the Hipparcos periodic variable stars into 26 types. The sub-sample with the most reliable variability types available in the literature is used to train supervised algorithms to characterize the type dependencies on a number of attributes. The most useful attributes evaluated with the random forest methodology include, in decreasing order of importance, the period, the amplitude, the V-I colour index, the absolute magnitude, the residual around the folded light-curve model, the magnitude distribution skewness and the amplitude of the second harmonic of the Fourier series model relative to that of the fundamental frequency. Random forests and a multi-stage scheme involving Bayesian network and Gaussian mixture methods lead to statistically equivalent results. In standard 10-fold cross-validation (CV) experiments, the rate of correct classification is between 90 and 100 per cent, depending on the variability type. The main mis-classification cases, up to a rate of about 10 per cent, arise due to confusion between SPB and ACV blue variables and between eclipsing binaries, ellipsoidal variables and other variability types. Our training set and the predicted types for the other Hipparcos periodic stars are available online.
Strong Laws of Large Numbers for Arrays of Rowwise NA and LNQD Random Variables
Jiangfeng Wang
2011-01-01
Full Text Available Some strong laws of large numbers and strong convergence properties for arrays of rowwise negatively associated and linearly negative quadrant dependent random variables are obtained. The results obtained not only generalize the result of Hu and Taylor to negatively associated and linearly negative quadrant dependent random variables, but also improve it.
Probabilistic norms and statistical convergence of random variables
Mohamad Rafi Segi Rahmat
2009-03-01
Full Text Available The paper extends certain stochastic convergence of sequences of Rk -valued random variables (namely, the convergence in probability, in Lp and almost surely to the context of E-valued random variables.
Random iteration with place dependent probabilities
Kapica, R
2011-01-01
Markov chains arising from random iteration of functions $S_{\\theta}:X\\to X$, $\\theta \\in \\Theta$, where $X$ is a Polish space and $\\Theta$ is arbitrary set of indices are considerd. At $x\\in X$, $\\theta$ is sampled from distribution $\\theta_x$ on $\\Theta$ and $\\theta_x$ are different for different $x$. Exponential convergence to a unique invariant measure is proved. This result is applied to case of random affine transformations on ${\\mathbb R}^d$ giving existence of exponentially attractive perpetuities with place dependent probabilities.
Energy-dependent variability from accretion flows
Zdziarski, Andrzej A.
2005-01-01
We develop a formalism to calculate energy-dependent fractional variability (rms) in accretion flows. We consider rms spectra resulting from radial dependencies of the level of local variability (as expected from propagation of disturbances in accretion flows) assuming the constant shape of the spectrum emitted at a given radius. We consider the cases when the variability of the flow is either coherent or incoherent between different radial zones. As example local emission, we consider blackb...
Moment inequalities for the partial sums of random variables
YANG; Shanchao
2001-01-01
［1］Yang Shanchao, Moment inequality of partial sum for a class of random variables and its application, Chinese Science Bulletin (in Chinese), 998, 43(7): 823.［2］Bryc, W., Smolenski, W., Moment conditions for almost sure convergence of weakly correlated variables, Proceedings of Amer, Math. Society, 993, 9(2): 629.［3］Peligrad, M., Invariance principles for mixing sequences of random variables, Ann. Probab., 982, 0(4): 968.［4］Peligrad, M., Convergence rates of the strong law for stationary mixing sequences, Z Wahr Verw Gebiete, 985, 70: 307.［5］Peligrad, M., On the central limit theorem for ρ-mixing sequences of random variables, Ann. Probab., 987, 5(4): 387.［6］Collomb, G., Propriétés de convergence presque compléte du prédicteur à noyau, Z Wahr Verw Gebiete, 984, 66: 44.［7］Matula, P., A note on the almost sure convergence of sums of negatively dependence random variables, Statist. Probab. Lett., 992, 5(3): 209.［8］Shao Qiman, Maximal inequalities for partial sums of ρ-mixing sequences, Ann. Probab., 995, 23(2): 948.［9］Shao Qiman, A moment inequality and its applications, Acta Mathematica Sinica (in Chinese), 988, 3(6): 736.［10］Shao Qiman, Complete convergence for ρ-mixing sequence, Acta Mathematica Sinica (in Chinese), 989, 32(3): 377.［11］Su Chun, Zhao Lincheng, Wang Yuebao, Moment inequalities for NA sequence and weak convergence, Science in China (Series A)(in Chinese), 996, 26(2): 09.［12］Zhang Lixin, Rosenthal type inequality for B-value strong mixing field and its application, Science in China (Series A)(in Chinese), 998, 28(4): 328.［13］Yang Shanchao, Moment inequality for mixing sequences and nonparametric estimation, Acta Mathemation Sinica (in Chinese), 997, 40(2): 27.［14］Joag-Dev, K., Proschan, F., Negative association of random variables with applications, Ann. Statist., 983, (1): 286.
PROBABILITY INEQUALITIES FOR SUMS OF INDEPENDENT UNBOUNDED RANDOM VARIABLES
张涤新; 王志诚
2001-01-01
The tail probability inequalities for the sum of independent unbounded random variables on a probability space ( Ω , T, P) were studied and a new method was proposed to treat the sum of independent unbounded random variables by truncating the original probability space (Ω, T, P ). The probability exponential inequalities for sums of independent unbounded random variables were given. As applications of the results, some interesting examples were given. The examples show that the method proposed in the paper and the results of the paper are quite useful in the study of the large sample properties of the sums of independent unbounded random variables.
Probability, random variables, and random processes theory and signal processing applications
Shynk, John J
2012-01-01
Probability, Random Variables, and Random Processes is a comprehensive textbook on probability theory for engineers that provides a more rigorous mathematical framework than is usually encountered in undergraduate courses. It is intended for first-year graduate students who have some familiarity with probability and random variables, though not necessarily of random processes and systems that operate on random signals. It is also appropriate for advanced undergraduate students who have a strong mathematical background. The book has the following features: Several app
On the product and ratio of Bessel random variables
Saralees Nadarajah
2005-01-01
Full Text Available The distributions of products and ratios of random variables are of interest in many areas of the sciences. In this paper, the exact distributions of the product |XY| and the ratio |X/Y| are derived when X and Y are independent Bessel function random variables. An application of the results is provided by tabulating the associated percentage points.
Fuzzy random variables — I. definitions and theorems
Kwakernaak, Huibert
1978-01-01
Fuzziness is discussed in the context of multivalued logic, and a corresponding view of fuzzy sets is given. Fuzzy random variables are introduced as random variables whose values are not real but fuzzy numbers, and subsequently redefined as a particular kind of fuzzy set. Expectations of fuzzy rand
Laws of large numbers for ratios of uniform random variables
Adler André
2015-09-01
Full Text Available Let {Xnn n ≥ 1} and {Yn, n ≥ 1} be two sequences of uniform random variables. We obtain various strong and weak laws of large numbers for the ratio of these two sequences. Even though these are uniform and naturally bounded random variables the ratios are not bounded and have an unusual behaviour creating Exact Strong Laws.
On order statistics from nonidentical discrete random variables
Yüzbaşı Bahadır
2016-01-01
Full Text Available In this study, pf and df of single order statistic of nonidentical discrete random variables are obtained. These functions are also expressed in integral form. Finally, pf and df of extreme of order statistics of random variables for the nonidentical discrete case are given.
On complete moment convergence for nonstationary negatively associated random variables
Mi-Hwa Ko
2016-05-01
Full Text Available Abstract The purpose of this paper is to establish the complete moment convergence for nonstationary negatively associated random variables satisfying the weak mean domination condition. The result is an improvement of complete convergence in Marcinkiewicz-Zygmund-type SLLN for negatively associated random variables in Kuczmaszewska (Acta Math. Hung. 128:116-130, 2010.
Moment inequalities for the partial sums of random variables
杨善朝
2001-01-01
This paper discusses the conditions under which Rosenthal type inequality is obtained from M-Z-B type inequality. And M-Z-B type inequality is proved for a wide class of random variables. Hence Rosenthal type inequalities for some classes of random variables are obtained.
Evolution variable dependence of jet substructure
Sakaki, Yasuhito
2015-01-01
Studies on jet substructure have evolved significantly in recent years. Jet substructure is essentially determined by QCD radiations and non-perturbative effects. Predictions of jet substructure are usually different among Monte Carlo event generators, and are governed by the parton shower algorithm implemented. For leading logarithmic parton shower, even though one of the core variables is the evolution variable, its choice is not unique. We examine evolution variable dependence of the jet substructure by developing a parton shower generator that interpolates between different evolution variables using a parameter $\\alpha$. Jet shape variables and associated jet rates for quark and gluon jets are used to demonstrate the $\\alpha$-dependence of the jet substructure. We find angular ordered shower predicts wider jets, while relative transverse momentum ($p_{\\bot}$) ordered shower predicts narrower jets. This is qualitatively in agreement with the missing phase space of $p_{\\bot}$ ordered showers. Such differenc...
Continuum Random Combs and Scale Dependent Spectral Dimension
Atkin, Max R; Wheater, John F
2011-01-01
Numerical computations have suggested that in causal dynamical triangulation models of quantum gravity the effective dimension of spacetime in the UV is lower than in the IR. In this paper we develop a simple model based on previous work on random combs, which share some of the properties of CDT, in which this effect can be shown to occur analytically. We construct a definition for short and long distance spectral dimensions and show that the random comb models exhibit scale dependent spectral dimension defined in this way. We also observe that a hierarchy of apparent spectral dimensions may be obtained in the cross-over region between UV and IR regimes for suitable choices of the continuum variables. Our main result is valid for a wide class of tooth length distributions thereby extending previous work on random combs by Durhuus et al.
Randomly weighted sums of subexponential random variables with application to ruin theory
Tang, Q.; Tsitsiashvili, G.
2003-01-01
Let {X k , 1 k n} be n independent and real-valued random variables with common subexponential distribution function, and let {k, 1 k n} be other n random variables independent of {X k , 1 k n} and satisfying a k b for some 0 < a b < for all 1 k n. This paper proves that the asymptotic relations P (
Energy-dependent variability from accretion flows
Zdziarski, A A
2005-01-01
We develop a formalism to calculate energy-dependent fractional variability (rms) in accretion flows. We consider rms spectra resulting from radial dependencies of the level of local variability (as expected from propagation of disturbances in accretion flows) assuming the constant shape of the spectrum emitted at a given radius. We consider the cases when the variability of the flow is either coherent or incoherent between different radial zones. As example local emission, we consider blackbody, Wien and thermal Comptonization spectra. In addition to numerical results, we present a number of analytical formulae for the resulting rms. We also find an analytical formula for the disc Wien spectrum, which we find to be a very good approximation to the disc blackbody. We compare our results to the rms spectrum observed in an ultrasoft state of GRS 1915+105.
Yue Bao WANG; Kai Yong WANG; Dong Ya CHENG
2006-01-01
In this paper, we obtain results on precise large deviations for non-random and random sums of negatively associated nonnegative random variables with common dominatedly varying tail distribution function. We discover that, under certain conditions, three precise large-deviation probabilities with different centering numbers are equivalent to each other. Furthermore, we investigate precise large deviations for sums of negatively associated nonnegative random variables with certain negatively dependent occurrences. The obtained results extend and improve the corresponding results of Ng, Tang, Yan and Yang (J. Appl. Prob., 41, 93-107, 2004).
Limiting Behavior of Weighted Sums of NOD Random Variables
De Hua QIU; Ping Yan CHEN
2011-01-01
The strong laws of large numbers and laws of the single logarithm for weighted sums of NOD random variables are established.The results presented generalize the corresponding results of Chen and Gan [5]in independent sequence case.
Designing neural networks that process mean values of random variables
Barber, Michael J. [AIT Austrian Institute of Technology, Innovation Systems Department, 1220 Vienna (Austria); Clark, John W. [Department of Physics and McDonnell Center for the Space Sciences, Washington University, St. Louis, MO 63130 (United States); Centro de Ciências Matemáticas, Universidade de Madeira, 9000-390 Funchal (Portugal)
2014-06-13
We develop a class of neural networks derived from probabilistic models posed in the form of Bayesian networks. Making biologically and technically plausible assumptions about the nature of the probabilistic models to be represented in the networks, we derive neural networks exhibiting standard dynamics that require no training to determine the synaptic weights, that perform accurate calculation of the mean values of the relevant random variables, that can pool multiple sources of evidence, and that deal appropriately with ambivalent, inconsistent, or contradictory evidence. - Highlights: • High-level neural computations are specified by Bayesian belief networks of random variables. • Probability densities of random variables are encoded in activities of populations of neurons. • Top-down algorithm generates specific neural network implementation of given computation. • Resulting “neural belief networks” process mean values of random variables. • Such networks pool multiple sources of evidence and deal properly with inconsistent evidence.
LIU; Yan(刘艳); HU; Yijun(胡亦钧)
2003-01-01
We prove large deviation results on the partial and random sums Sn = ∑ni=1 Xi, n≥1; S(t) =∑N(t)i=1 Xi, t≥0, where {N(t);t≥0} are non-negative integer-valued random variables and {Xn;n≥1} areindependent non-negative random variables with distribution, Fn, of Xn, independent of {N(t); t≥0}. Specialattention is paid to the distribution of dominated variation.
Exponential Inequalities for Positively Associated Random Variables and Applications
Yang Shanchao
2008-01-01
Full Text Available Abstract We establish some exponential inequalities for positively associated random variables without the boundedness assumption. These inequalities improve the corresponding results obtained by Oliveira (2005. By one of the inequalities, we obtain the convergence rate for the case of geometrically decreasing covariances, which closes to the optimal achievable convergence rate for independent random variables under the Hartman-Wintner law of the iterated logarithm and improves the convergence rate derived by Oliveira (2005 for the above case.
Some Limit Theorems for Negatively Associated Random Variables
Yu Miao; Wenfei Xu; Shanshan Chen; Andre Adler
2014-08-01
Let $\\{X_n,n≥ 1\\}$ be a sequence of negatively associated random variables. The aim of this paper is to establish some limit theorems of negatively associated sequence, which include the $L^p$-convergence theorem and Marcinkiewicz–Zygmund strong law of large numbers. Furthermore, we consider the strong law of sums of order statistics, which are sampled from negatively associated random variables.
A Note on the Sum of Correlated Gamma Random Variables
Paris, Jose F
2011-01-01
The sum of correlated gamma random variables appears in the analysis of many wireless communications systems, e.g. in systems under Nakagami-m fading. In this Letter we obtain exact expressions for the probability density function (PDF) and the cumulative distribution function (CDF) of the sum of arbitrarily correlated gamma variables in terms of certain Lauricella functions.
PaCAL: A Python Package for Arithmetic Computations with Random Variables
Marcin Korze?
2014-05-01
Full Text Available In this paper we present PaCAL, a Python package for arithmetical computations on random variables. The package is capable of performing the four arithmetic operations: addition, subtraction, multiplication and division, as well as computing many standard functions of random variables. Summary statistics, random number generation, plots, and histograms of the resulting distributions can easily be obtained and distribution parameter ?tting is also available. The operations are performed numerically and their results interpolated allowing for arbitrary arithmetic operations on random variables following practically any probability distribution encountered in practice. The package is easy to use, as operations on random variables are performed just as they are on standard Python variables. Independence of random variables is, by default, assumed on each step but some computations on dependent random variables are also possible. We demonstrate on several examples that the results are very accurate, often close to machine precision. Practical applications include statistics, physical measurements or estimation of error distributions in scienti?c computations.
Optical variability of quasars: a damped random walk
Ivezic, Zeljko
2013-01-01
A damped random walk is a stochastic process, defined by an exponential covariance matrix that behaves as a random walk for short time scales and asymptotically achieves a finite variability amplitude at long time scales. Over the last few years, it has been demonstrated, mostly but not exclusively using SDSS data, that a damped random walk model provides a satisfactory statistical description of observed quasar variability in the optical wavelength range, for rest-frame timescales from 5 days to 2000 days. The best-fit characteristic timescale and asymptotic variability amplitude scale with the luminosity, black hole mass, and rest wavelength, and appear independent of redshift. In addition to providing insights into the physics of quasar variability, the best-fit model parameters can be used to efficiently separate quasars from stars in imaging surveys with adequate long-term multi-epoch data, such as expected from LSST.
New Results On the Sum of Two Generalized Gaussian Random Variables
Soury, Hamza
2015-01-01
We propose in this paper a new method to compute the characteristic function (CF) of generalized Gaussian (GG) random variable in terms of the Fox H function. The CF of the sum of two independent GG random variables is then deduced. Based on this results, the probability density function (PDF) and the cumulative distribution function (CDF) of the sum distribution are obtained. These functions are expressed in terms of the bivariate Fox H function. Next, the statistics of the distribution of the sum, such as the moments, the cumulant, and the kurtosis, are analyzed and computed. Due to the complexity of bivariate Fox H function, a solution to reduce such complexity is to approximate the sum of two independent GG random variables by one GG random variable with suitable shape factor. The approximation method depends on the utility of the system so three methods of estimate the shape factor are studied and presented.
Applying Free Random Variables to Random Matrix Analysis of Financial Data
Burda, Z; Jurkiewicz, J; Nowak, M A; Papp, G; Zahed, I
2006-01-01
We apply the concept of free random variables to correlated Wishart random matrix models. We give a comprehensive rederivation of various spectral densities for a number of financial covariance matrices involving stocks returns without and with exponentially weighted moving averages. We show through simple models how to identify the pertinent underlying correlations. We extend our results to Levy-Wishart random matrix models whereby the risk factors are heavy tailed.
Random Time Dependent Resistance Analysis on Reinforced Concrete Structures
GUAN Chang-sheng; WU Ling
2002-01-01
The analysis method on random time dependence of reinforced concrete material is introduced,the effect mechanism on reinforced concrete are discussed, and the random time dependence resistance of reinforced concrete is studied. Furthermore, the corrosion of steel bar in reinforced concrete structures is analyzed. A practical statistical method of evaluating the random time dependent resistance, which includes material, structural size and calculation influence, is also established. In addition, an example of predicting random time dependent resistance of reinforced concrete structural element is given.
Independent, dependent, and other variables in healthcare and chaplaincy research.
Flannelly, Laura T; Flannelly, Kevin J; Jankowski, Katherine R B
2014-01-01
This article begins by defining the term variable and the terms independent variable and dependent variable, providing examples of each. It then proceeds to describe and discuss synonyms for the terms independent variable and dependent variable, including treatment, intervention, predictor, and risk factor, and synonyms for dependent variable, such as response variables and outcomes. The article explains that the terms extraneous, nuisance, and confounding variables refer to any variable that can interfere with the ability to establish relationships between independent variables and dependent variables, and it describes ways to control for such confounds. It further explains that even though intervening, mediating, and moderating variables explicitly alter the relationship between independent variables and dependent variables, they help to explain the causal relationship between them. In addition, the article links terminology about variables with the concept of levels of measurement in research.
SHEN Ai-ting; ZHU Hua-yan; ZHANG Ying
2014-01-01
Some exponential inequalities and complete convergence are established for ex-tended negatively dependent(END) random variables. The inequalities extend and improve the results of Kim and Kim(On the exponential inequality for negative dependent sequence. Communications of the Korean Mathematical Society, 2007, 22(2): 315-321) and Nooghabi and Azarnoosh(Exponential inequality for negatively associated random variables. Statisti-cal Papers, 2009, 50 (2): 419-428). We also obtain the convergence rate O(n-1/2 ln1/2 n) for the strong law of large numbers, which improves the corresponding ones of Kim and Kim, and Nooghabi and Azarnoosh.
Age-dependent branching processes in random environments
2008-01-01
We consider an age-dependent branching process in random environments. The environments are represented by a stationary and ergodic sequence ξ = (ξ0,ξ1,...) of random variables. Given an environment ξ, the process is a non-homogenous Galton-Watson process, whose particles in n-th generation have a life length distribution G(ξn) on R+, and reproduce independently new particles according to a probability law p(ξn) on N. Let Z(t) be the number of particles alive at time t. We first find a characterization of the conditional probability generating function of Z(t) (given the environment ξ) via a functional equation, and obtain a criterion for almost certain extinction of the process by comparing it with an embedded Galton-Watson process. We then get expressions of the conditional mean EξZ(t) and the global mean EZ(t), and show their exponential growth rates by studying a renewal equation in random environments.
Age-dependent branching processes in random environments
LI YingQiu; LIU QuanSheng
2008-01-01
We consider an age-dependent branching process in random environments.The environments are represented by a stationary and ergodic sequence ξ = (ξ0,ξ1,...) of random variables.Given an environment ξ,the process is a non-homogenous Galton-Watson process,whose particles in n-th generation have a life length distribution G(ξn) on R+,and reproduce independently new particles according to a probability law p(ξn) on N.Let Z(t) be the number of particles alive at time t.We first find a characterization of the conditional probability generating function of Z(t) (given the environment ξ) via a functional equation,and obtain a criterion for almost certain extinction of the process by comparing it with an embedded Galton-Watson process.We then get expressions of the conditional mean EξZ(t) and the global mean EZ(t),and show their exponential growth rates by studying a renewal equation in random environments.
Bayesian nonparametric centered random effects models with variable selection.
Yang, Mingan
2013-03-01
In a linear mixed effects model, it is common practice to assume that the random effects follow a parametric distribution such as a normal distribution with mean zero. However, in the case of variable selection, substantial violation of the normality assumption can potentially impact the subset selection and result in poor interpretation and even incorrect results. In nonparametric random effects models, the random effects generally have a nonzero mean, which causes an identifiability problem for the fixed effects that are paired with the random effects. In this article, we focus on a Bayesian method for variable selection. We characterize the subject-specific random effects nonparametrically with a Dirichlet process and resolve the bias simultaneously. In particular, we propose flexible modeling of the conditional distribution of the random effects with changes across the predictor space. The approach is implemented using a stochastic search Gibbs sampler to identify subsets of fixed effects and random effects to be included in the model. Simulations are provided to evaluate and compare the performance of our approach to the existing ones. We then apply the new approach to a real data example, cross-country and interlaboratory rodent uterotrophic bioassay.
A random energy model for size dependence : recurrence vs. transience
Külske, Christof
1998-01-01
We investigate the size dependence of disordered spin models having an infinite number of Gibbs measures in the framework of a simplified 'random energy model for size dependence'. We introduce two versions (involving either independent random walks or branching processes), that can be seen as gener
The Benford phenomenon for random variables. Discussion of Feller's way
Valadier, Michel
2012-01-01
This paper is devoted to the first digit of a random variable. We will discuss some arguments starting from Feller (1966) and rely specially on Engel-Leuenberger (2003), D\\"umbgen-Leuenberger (2008), Gauvrit-Delahaye (2008--2009), Berger (2010). Some "disaster"appears. We will not discuss papers relying on Fourier Analysis.
An infinite-dimensional weak KAM theory via random variables
Gomes, Diogo A.
2016-08-31
We develop several aspects of the infinite-dimensional Weak KAM theory using a random variables\\' approach. We prove that the infinite-dimensional cell problem admits a viscosity solution that is a fixed point of the Lax-Oleinik semigroup. Furthermore, we show the existence of invariant minimizing measures and calibrated curves defined on R.
Limit theorems for multi-indexed sums of random variables
Klesov, Oleg
2014-01-01
Presenting the first unified treatment of limit theorems for multiple sums of independent random variables, this volume fills an important gap in the field. Several new results are introduced, even in the classical setting, as well as some new approaches that are simpler than those already established in the literature. In particular, new proofs of the strong law of large numbers and the Hajek-Renyi inequality are detailed. Applications of the described theory include Gibbs fields, spin glasses, polymer models, image analysis and random shapes. Limit theorems form the backbone of probability theory and statistical theory alike. The theory of multiple sums of random variables is a direct generalization of the classical study of limit theorems, whose importance and wide application in science is unquestionable. However, to date, the subject of multiple sums has only been treated in journals. The results described in this book will be of interest to advanced undergraduates, graduate students and researchers who ...
Characterizing heart rate variability by scale-dependent Lyapunov exponent
Hu, Jing; Gao, Jianbo; Tung, Wen-wen
2009-06-01
Previous studies on heart rate variability (HRV) using chaos theory, fractal scaling analysis, and many other methods, while fruitful in many aspects, have produced much confusion in the literature. Especially the issue of whether normal HRV is chaotic or stochastic remains highly controversial. Here, we employ a new multiscale complexity measure, the scale-dependent Lyapunov exponent (SDLE), to characterize HRV. SDLE has been shown to readily characterize major models of complex time series including deterministic chaos, noisy chaos, stochastic oscillations, random 1/f processes, random Levy processes, and complex time series with multiple scaling behaviors. Here we use SDLE to characterize the relative importance of nonlinear, chaotic, and stochastic dynamics in HRV of healthy, congestive heart failure, and atrial fibrillation subjects. We show that while HRV data of all these three types are mostly stochastic, the stochasticity is different among the three groups.
Generation of correlated finite alphabet waveforms using gaussian random variables
Ahmed, Sajid
2016-01-13
Various examples of methods and systems are provided for generation of correlated finite alphabet waveforms using Gaussian random variables in, e.g., radar and communication applications. In one example, a method includes mapping an input signal comprising Gaussian random variables (RVs) onto finite-alphabet non-constant-envelope (FANCE) symbols using a predetermined mapping function, and transmitting FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The FANCE waveforms can be based upon the mapping of the Gaussian RVs onto the FANCE symbols. In another example, a system includes a memory unit that can store a plurality of digital bit streams corresponding to FANCE symbols and a front end unit that can transmit FANCE waveforms through a uniform linear array of antenna elements to obtain a corresponding beampattern. The system can include a processing unit that can encode the input signal and/or determine the mapping function.
On the behavior of the product of independent random variables
SU; Chun; CHEN; Yu
2006-01-01
For two independent non-negative random variables X and Y, we treat X as the initial variable of major importance and Y as a modifier (such as the interest rate of a portfolio).Stability in the tail behaviors of the product compared with that of the original variable X is of practical interests. In this paper, we study the tail behaviors of the product XY when the distribution of X belongs to the classes L and S, respectively. Under appropriate conditions, we show that the distribution of the product XY is in the same class as X when X belongs to class L or S, in other words, classes L and S are stable under some mild conditions on the distribution of Y. We also show that if the distribution of X is in class L(γ) (γ＞ 0) and continuous, then the product XY is in L if and only if Y is unbounded.
Cardinality-dependent Variability in Orthogonal Variability Models
Mærsk-Møller, Hans Martin; Jørgensen, Bo Nørregaard
2012-01-01
During our work on developing and running a software product line for eco-sustainable greenhouse-production software tools, which currently have three products members we have identified a need for extending the notation of the Orthogonal Variability Model (OVM) to support what we refer to as car......During our work on developing and running a software product line for eco-sustainable greenhouse-production software tools, which currently have three products members we have identified a need for extending the notation of the Orthogonal Variability Model (OVM) to support what we refer...
Concentrated Hitting Times of Randomized Search Heuristics with Variable Drift
Lehre, Per Kristian; Witt, Carsten
2014-01-01
these results handle a position-dependent (variable) drift that was not covered by previous drift theorems with tail bounds. Moreover, our theorem can be specialized into virtually all existing drift theorems with drift towards the target from the literature. Finally, user-friendly specializations...
Moderate Deviations for Random Sums of Heavy-Tailed Random Variables
Fu Qing GAO
2007-01-01
Let{Xn ;n ≥ 1}be a sequence of independent non-negative random variables with commondistribution function F having extended regularly varying tail and finite mean μ = E(X1) and let{N(t);t≥0}be a random process taking non-negative integer values with finite mean λ(t) = E(N(t))x) uniformly for x ∈[γb(t),∞) are obtained,where γ 0 and b(t) can be taken to be a positive functionwith lim t→∞ b(t)/λ(t) = 0.
On the Linear Combination of Exponential and Gamma Random Variables
Samuel Kotz
2005-06-01
Full Text Available Abstract: The exact distribution of the linear combination ÃŽÂ± X + ÃŽÂ² Y is derived when X and Y are exponential and gamma random variables distributed independently of each other. A measure of entropy of the linear combination is investigated. We also provide computer programs for generating tabulations of the percentage points associated with the linear combination. The work is motivated by examples in automation, control, fuzzy sets, neurocomputing and other areas of computer science.
Generation of correlated finite alphabet waveforms using gaussian random variables
Jardak, Seifallah
2014-09-01
Correlated waveforms have a number of applications in different fields, such as radar and communication. It is very easy to generate correlated waveforms using infinite alphabets, but for some of the applications, it is very challenging to use them in practice. Moreover, to generate infinite alphabet constant envelope correlated waveforms, the available research uses iterative algorithms, which are computationally very expensive. In this work, we propose simple novel methods to generate correlated waveforms using finite alphabet constant and non-constant-envelope symbols. To generate finite alphabet waveforms, the proposed method map the Gaussian random variables onto the phase-shift-keying, pulse-amplitude, and quadrature-amplitude modulation schemes. For such mapping, the probability-density-function of Gaussian random variables is divided into M regions, where M is the number of alphabets in the corresponding modulation scheme. By exploiting the mapping function, the relationship between the cross-correlation of Gaussian and finite alphabet symbols is derived. To generate equiprobable symbols, the area of each region is kept same. If the requirement is to have each symbol with its own unique probability, the proposed scheme allows us that as well. Although, the proposed scheme is general, the main focus of this paper is to generate finite alphabet waveforms for multiple-input multiple-output radar, where correlated waveforms are used to achieve desired beampatterns. © 2014 IEEE.
Analysis of Secret Key Randomness Exploiting the Radio Channel Variability
Taghrid Mazloum
2015-01-01
Full Text Available A few years ago, physical layer based techniques have started to be considered as a way to improve security in wireless communications. A well known problem is the management of ciphering keys, both regarding the generation and distribution of these keys. A way to alleviate such difficulties is to use a common source of randomness for the legitimate terminals, not accessible to an eavesdropper. This is the case of the fading propagation channel, when exact or approximate reciprocity applies. Although this principle has been known for long, not so many works have evaluated the effect of radio channel properties in practical environments on the degree of randomness of the generated keys. To this end, we here investigate indoor radio channel measurements in different environments and settings at either 2.4625 GHz or 5.4 GHz band, of particular interest for WIFI related standards. Key bits are extracted by quantizing the complex channel coefficients and their randomness is evaluated using the NIST test suite. We then look at the impact of the carrier frequency, the channel variability in the space, time, and frequency degrees of freedom used to construct a long secret key, in relation to the nature of the radio environment such as the LOS/NLOS character.
Variability dependencies in product family engineering
Jaring, M; Bosch, J; VanDerLinden, F
2004-01-01
In a product family context, software architects anticipate product diversification and design architectures that support variants in both space (multiple contexts) and time (changing contexts). Product diversification is based on the concept of variability: a single architecture and a set of compon
Strong Law of Large Numb ers for Array of Rowwise AANA Random Variables
CHEN Zhi-yong; LIU Ting-ting; WANG Xue-jun; LI Xiao-qin
2014-01-01
In this article, the strong laws of large numbers for array of rowwise asymptot-ically almost negatively associated(AANA) random variables are studied. Some suﬃcient conditions for strong laws of large numbers for array of rowwise AANA random variables are presented without assumption of identical distribution. Our results extend the corresponding ones for independent random variables to case of AANA random variables.
Partial summations of stationary sequences of non-Gaussian random variables
Mohr, Gunnar; Ditlevsen, Ove Dalager
1996-01-01
-Gaussian variables up to the moments of the fourth order [Winterstein, S. R. Nonlinear vibration models for extremes and fatigue. J. Engng Mech. ASCE 114 (1988) 1772-1790](1). A method to obtain the Winterstein approximation to a partial sum of a sequence of Winterstein approximations is explained and results...... of convergence of the distribution of a sum (or an integral) of mutually dependent random variables to the Gaussian distribution. The paper is closely related to the work in Ditlevsen el al. [Ditlevsen, O., Mohr, G. & Hoffmeyer, P. Integration of non-Gaussian fields. Prob. Engng Mech 11 (1996) 15-23](2)....
Bayesian Network Models for Local Dependence among Observable Outcome Variables
Almond, Russell G.; Mulder, Joris; Hemat, Lisa A.; Yan, Duanli
2009-01-01
Bayesian network models offer a large degree of flexibility for modeling dependence among observables (item outcome variables) from the same task, which may be dependent. This article explores four design patterns for modeling locally dependent observations: (a) no context--ignores dependence among observables; (b) compensatory context--introduces…
Automatic Probabilistic Program Verification through Random Variable Abstraction
Barsotti, Damián; 10.4204/EPTCS.28.3
2010-01-01
The weakest pre-expectation calculus has been proved to be a mature theory to analyze quantitative properties of probabilistic and nondeterministic programs. We present an automatic method for proving quantitative linear properties on any denumerable state space using iterative backwards fixed point calculation in the general framework of abstract interpretation. In order to accomplish this task we present the technique of random variable abstraction (RVA) and we also postulate a sufficient condition to achieve exact fixed point computation in the abstract domain. The feasibility of our approach is shown with two examples, one obtaining the expected running time of a probabilistic program, and the other the expected gain of a gambling strategy. Our method works on general guarded probabilistic and nondeterministic transition systems instead of plain pGCL programs, allowing us to easily model a wide range of systems including distributed ones and unstructured programs. We present the operational and weakest pr...
Generating Correlated QPSK Waveforms By Exploiting Real Gaussian Random Variables
Jardak, Seifallah
2012-11-01
The design of waveforms with specified auto- and cross-correlation properties has a number of applications in multiple-input multiple-output (MIMO) radar, one of them is the desired transmit beampattern design. In this work, an algorithm is proposed to generate quadrature phase shift- keying (QPSK) waveforms with required cross-correlation properties using real Gaussian random-variables (RV’s). This work can be considered as the extension of what was presented in [1] to generate BPSK waveforms. This work will be extended for the generation of correlated higher-order phase shift-keying (PSK) and quadrature amplitude modulation (QAM) schemes that can better approximate the desired beampattern.
Radio Variability and Random Walk Noise Properties of Four Blazars
Park, Jong-Ho
2014-01-01
We present the results of a time series analysis of the long-term radio lightcurves of four blazars: 3C 279, 3C 345, 3C 446, and BL Lacertae. We exploit the data base of the University of Michigan Radio Astronomy Observatory (UMRAO) monitoring program which provides densely sampled lightcurves spanning 32 years in time in three frequency bands located at 4.8, 8, and 14.5 GHz. Our sources show mostly flat or inverted (spectral indices -0.5 < alpha < 0) spectra, in agreement with optically thick emission. All lightcurves show strong variability on all time scales. Analyzing the time lags between the lightcurves from different frequency bands, we find that we can distinguish high-peaking flares and low-peaking flares in accord with the classification of Valtaoja et al. (1992). The periodograms (temporal power spectra) of the observed lightcurves are consistent with random-walk powerlaw noise without any indication of (quasi-)periodic variability. The fact that all four sources studied are in agreement with...
Instrumental variables and Mendelian randomization with invalid instruments
Kang, Hyunseung
Instrumental variables (IV) methods have been widely used to determine the causal effect of a treatment, exposure, policy, or an intervention on an outcome of interest. The IV method relies on having a valid instrument, a variable that is (A1) associated with the exposure, (A2) has no direct effect on the outcome, and (A3) is unrelated to the unmeasured confounders associated with the exposure and the outcome. However, in practice, finding a valid instrument, especially those that satisfy (A2) and (A3), can be challenging. For example, in Mendelian randomization studies where genetic markers are used as instruments, complete knowledge about instruments' validity is equivalent to complete knowledge about the involved genes' functions. The dissertation explores the theory, methods, and application of IV methods when invalid instruments are present. First, when we have multiple candidate instruments, we establish a theoretical bound whereby causal effects are only identified as long as less than 50% of instruments are invalid, without knowing which of the instruments are invalid. We also propose a fast penalized method, called sisVIVE, to estimate the causal effect. We find that sisVIVE outperforms traditional IV methods when invalid instruments are present both in simulation studies as well as in real data analysis. Second, we propose a robust confidence interval under the multiple invalid IV setting. This work is an extension of our work on sisVIVE. However, unlike sisVIVE which is robust to violations of (A2) and (A3), our confidence interval procedure provides honest coverage even if all three assumptions, (A1)-(A3), are violated. Third, we study the single IV setting where the one IV we have may actually be invalid. We propose a nonparametric IV estimation method based on full matching, a technique popular in causal inference for observational data, that leverages observed covariates to make the instrument more valid. We propose an estimator along with
Unique Measure for Time-Dependent Random Dynamical Systems
Varner, Gregory
2016-01-01
This paper proves the uniqueness of measure for the two-dimensional Navier-Stokes equations under a random kick-force and a time-dependent deterministic force. By extending a result for uniqueness of measure for time-homogeneous Markov processes to the time-inhomogeneous case, it is shown that the measures are exponentially mixing for the 2D Navier-Stokes equations on the sphere.
Automatic Probabilistic Program Verification through Random Variable Abstraction
Damián Barsotti
2010-06-01
Full Text Available The weakest pre-expectation calculus has been proved to be a mature theory to analyze quantitative properties of probabilistic and nondeterministic programs. We present an automatic method for proving quantitative linear properties on any denumerable state space using iterative backwards fixed point calculation in the general framework of abstract interpretation. In order to accomplish this task we present the technique of random variable abstraction (RVA and we also postulate a sufficient condition to achieve exact fixed point computation in the abstract domain. The feasibility of our approach is shown with two examples, one obtaining the expected running time of a probabilistic program, and the other the expected gain of a gambling strategy. Our method works on general guarded probabilistic and nondeterministic transition systems instead of plain pGCL programs, allowing us to easily model a wide range of systems including distributed ones and unstructured programs. We present the operational and weakest precondition semantics for this programs and prove its equivalence.
Random recurrence equations and ruin in a Markov-dependent stochastic economic environment
Collamore, Jeffrey F.
2009-01-01
We develop sharp large deviation asymptotics for the probability of ruin in a Markov-dependent stochastic economic environment and study the extremes for some related Markovian processes which arise in financial and insurance mathematics, related to perpetuities and the ARCH(1) and GARCH(1,1) time...... series models. Our results build upon work of Goldie, who has developed tail asymptotics applicable for independent sequences of random variables subject to a random recurrence equation. In contrast, we adopt a general approach based on the theory of Harris recurrent Markov chains and the associated...
Almost Sure Convergence of the General Jamison Weighted Sum of B-Valued Random Variables
Chun SU; Tie Jun TONG
2004-01-01
In this paper, two new functions are introduced to depict the Jamison weighted sum of random variables instead using the common methods, their properties and relationships are systematically discussed. We also analysed the implication of the conditions in previous papers. Then we apply these consequences to B-valued random variables, and greatly improve the original results of the strong convergence of the general Jamison weighted sum. Furthermore, our discussions are useful to the corresponding questions of real-valued random variables.
A new Hedging algorithm and its application to inferring latent random variables
Freund, Yoav
2008-01-01
We present a new online learning algorithm for cumulative discounted gain. This learning algorithm does not use exponential weights on the experts. Instead, it uses a weighting scheme that depends on the regret of the master algorithm relative to the experts. In particular, experts whose discounted cumulative gain is smaller (worse) than that of the master algorithm receive zero weight. We also sketch how a regret-based algorithm can be used as an alternative to Bayesian averaging in the context of inferring latent random variables.
Stable limits for sums of dependent infinite variance random variables
Bartkiewicz, Katarzyna; Jakubowski, Adam; Mikosch, Thomas;
2011-01-01
The aim of this paper is to provide conditions which ensure that the affinely transformed partial sums of a strictly stationary process converge in distribution to an infinite variance stable distribution. Conditions for this convergence to hold are known in the literature. However, most...... of these results are qualitative in the sense that the parameters of the limit distribution are expressed in terms of some limiting point process. In this paper we will be able to determine the parameters of the limiting stable distribution in terms of some tail characteristics of the underlying stationary...
Hassan, Mohammad Khaled
2016-01-01
Bias Temperature Instability (BTI) is a major reliability concern in CMOS technology, especially with High dielectric constant (High-\\k{appa}/HK) metal gate (MG) transistors. In addition, the time independent process induced variation has also increased because of the aggressive scaling down of devices. As a result, the faster devices at the lower threshold voltage distribution tail experience higher stress, leading to additional skewness in the BTI degradation. Since time dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) in NMOS devices are correlated to BTI, it is necessary to investigate the effect of time zero variability on all these effects simultaneously. To that effect, we propose a simulation framework to model and analyze the impact of time-zero variability (in particular, random dopant fluctuations) on different aging effects. For small area devices (~1000 nm2) in 30nm technology, we observe significant effect of Random Dopant Fluctuation (RDF) on BTI induced variabili...
Statistical Dependence of Pipe Breaks on Explanatory Variables
Patricia Gómez-Martínez
2017-02-01
Full Text Available Aging infrastructure is the main challenge currently faced by water suppliers. Estimation of assets lifetime requires reliable criteria to plan assets repair and renewal strategies. To do so, pipe break prediction is one of the most important inputs. This paper analyzes the statistical dependence of pipe breaks on explanatory variables, determining their optimal combination and quantifying their influence on failure prediction accuracy. A large set of registered data from Madrid water supply network, managed by Canal de Isabel II, has been filtered, classified and studied. Several statistical Bayesian models have been built and validated from the available information with a technique that combines reference periods of time as well as geographical location. Statistical models of increasing complexity are built from zero up to five explanatory variables following two approaches: a set of independent variables or a combination of two joint variables plus an additional number of independent variables. With the aim of finding the variable combination that provides the most accurate prediction, models are compared following an objective validation procedure based on the model skill to predict the number of pipe breaks in a large set of geographical locations. As expected, model performance improves as the number of explanatory variables increases. However, the rate of improvement is not constant. Performance metrics improve significantly up to three variables, but the tendency is softened for higher order models, especially in trunk mains where performance is reduced. Slight differences are found between trunk mains and distribution lines when selecting the most influent variables and models.
Sampling designs dependent on sample parameters of auxiliary variables
Wywiał, Janusz L
2015-01-01
The book offers a valuable resource for students and statisticians whose work involves survey sampling. An estimation of the population parameters in finite and fixed populations assisted by auxiliary variables is considered. New sampling designs dependent on moments or quantiles of auxiliary variables are presented on the background of the classical methods. Accuracies of the estimators based on original sampling design are compared with classical estimation procedures. Specific conditional sampling designs are applied to problems of small area estimation as well as to estimation of quantiles of variables under study. .
Ji-hua Xu; Jing-hui Zhao
2000-01-01
After giving the representation of moment gqnerating function for the S-λ type random variable by solving a differential equation, we prove that this type random variable is of regular n-r order moment. Furthermore we establish the higher order asymptotic formula for generalized Feller operators by making use of the generalized Taylor formula.
Bogdan Gheorghe Munteanu
2013-01-01
Full Text Available Using the stochastic approximations, in this paper it was studiedthe convergence in distribution of the fractional parts of the sum of random variables to the truncated exponential distribution with parameter lambda. This fact is feasible by means of the Fourier-Stieltjes sequence (FSS of the random variable.
Raw and Central Moments of Binomial Random Variables via Stirling Numbers
Griffiths, Martin
2013-01-01
We consider here the problem of calculating the moments of binomial random variables. It is shown how formulae for both the raw and the central moments of such random variables may be obtained in a recursive manner utilizing Stirling numbers of the first kind. Suggestions are also provided as to how students might be encouraged to explore this…
LARGE DEVIATION FOR THE EMPIRICAL CORRELATION COEFFICIENT OF TWO GAUSSIAN RANDOM VARIABLES
Shen Si
2007-01-01
In this article, the author obtains the large deviation principles for the empirical correlation coefficient of two Gaussian random variables X and Y. Especially, when considering two independent Gaussian random variables X, Y with the means EX, EY(both known), wherein the author gives two kinds of different proofs and gets the same results.
Complete Convergence for Arrays of Rowwise ϕ-mixing Random Variables
LI Jing
2013-01-01
In the paper, the complete convergence for arrays of rowwise ϕ-mixing random variables is studied. Some sufficient conditions for complete convergence for an array of row-wiseϕ-mixing random variables without assumptions of identical distribution and stochastic domination are presented.
An almost Sure Central Limit Theorem for the Weight Function Sequences of NA Random Variables
Qunying Wu
2011-08-01
Consider the weight function sequences of NA random variables. This paper proves that the almost sure central limit theorem holds for the weight function sequences of NA random variables. Our results generalize and improve those on the almost sure central limit theorem previously obtained from the i.i.d. case to NA sequences.
Mingle Guo
2012-01-01
Full Text Available The complete moment convergence of weighted sums for arrays of rowwise negatively associated random variables is investigated. Some sufficient conditions for complete moment convergence of weighted sums for arrays of rowwise negatively associated random variables are established. Moreover, the results of Baek et al. (2008, are complemented. As an application, the complete moment convergence of moving average processes based on a negatively associated random sequences is obtained, which improves the result of Li et al. (2004.
Stochastic Optimal Estimation with Fuzzy Random Variables and Fuzzy Kalman Filtering
FENG Yu-hu
2005-01-01
By constructing a mean-square performance index in the case of fuzzy random variable, the optimal estimation theorem for unknown fuzzy state using the fuzzy observation data are given. The state and output of linear discrete-time dynamic fuzzy system with Gaussian noise are Gaussian fuzzy random variable sequences. An approach to fuzzy Kalman filtering is discussed. Fuzzy Kalman filtering contains two parts: a real-valued non-random recurrence equation and the standard Kalman filtering.
Testing Dependent Correlations with Nonoverlapping Variables: A Monte Carlo Simulation
Silver, N. Clayton; Hittner, James B.; May, Kim
2004-01-01
The authors conducted a Monte Carlo simulation of 4 test statistics or comparing dependent correlations with no variables in common. Empirical Type 1 error rates and power estimates were determined for K. Pearson and L. N. G. Filon's (1898) z, O. J. Dunn and V. A. Clark's (1969) z, J. H. Steiger's (1980) original modification of Dunn and Clark's…
Local search methods based on variable focusing for random K -satisfiability
Lemoy, Rémi; Alava, Mikko; Aurell, Erik
2015-01-01
We introduce variable focused local search algorithms for satisfiabiliity problems. Usual approaches focus uniformly on unsatisfied clauses. The methods described here work by focusing on random variables in unsatisfied clauses. Variants are considered where variables are selected uniformly and randomly or by introducing a bias towards picking variables participating in several unsatistified clauses. These are studied in the case of the random 3-SAT problem, together with an alternative energy definition, the number of variables in unsatisfied constraints. The variable-based focused Metropolis search (V-FMS) is found to be quite close in performance to the standard clause-based FMS at optimal noise. At infinite noise, instead, the threshold for the linearity of solution times with instance size is improved by picking preferably variables in several UNSAT clauses. Consequences for algorithmic design are discussed.
Gosho, Masahiko; Maruo, Kazushi; Ishii, Ryota; Hirakawa, Akihiro
2016-11-16
The total score, which is calculated as the sum of scores in multiple items or questions, is repeatedly measured in longitudinal clinical studies. A mixed effects model for repeated measures method is often used to analyze these data; however, if one or more individual items are not measured, the method cannot be directly applied to the total score. We develop two simple and interpretable procedures that infer fixed effects for a longitudinal continuous composite variable. These procedures consider that the items that compose the total score are multivariate longitudinal continuous data and, simultaneously, handle subject-level and item-level missing data. One procedure is based on a multivariate marginalized random effects model with a multiple of Kronecker product covariance matrices for serial time dependence and correlation among items. The other procedure is based on a multiple imputation approach with a multivariate normal model. In terms of the type-1 error rate and the bias of treatment effect in total score, the marginalized random effects model and multiple imputation procedures performed better than the standard mixed effects model for repeated measures analysis with listwise deletion and single imputations for handling item-level missing data. In particular, the mixed effects model for repeated measures with listwise deletion resulted in substantial inflation of the type-1 error rate. The marginalized random effects model and multiple imputation methods provide for a more efficient analysis by fully utilizing the partially available data, compared to the mixed effects model for repeated measures method with listwise deletion.
Muhammad Farrukh Yaqub
2012-01-01
Full Text Available This paper presents a new method for single phase variable voltage inverter based on Random Pulse Width Modulation. In Random Pulse Width Modulation based inverter, the frequency spectrum of the output current and voltage waveforms becomes continuous because of the randomization of the switching function of the devices controlling the output voltages. This paper establishes a theory that if the distributions of the random numbers generated by the random source are kept within certain limit with respect to the peak value of reference sinusoidal waveform, the frequency spectrum can be controlled. On the basis of the results, a novel drive using variable tap changing transformer (optional and adaptive random number generator, to control the ratio between the numbers generated by the random source and the reference waveform has been suggested that will guarantee a better power quality profile for a broad range of output voltages.
THE STRUCTURE AND PRECISE MODERATE DEVIATIONS OF RANDOM VARIABLES WITH DOMINATEDLY VARYING TAILS
WANG Yuebao; YANG Yang
2005-01-01
This paper shows the structure of the random variables with dominatedly varying tails and that of the associated random variables,and obtains some results on these r.v.s' precise moderate deviations with random centralizing constants,which extend the boundary γλ(t) of large deviations to γ(λ(t))1/s,where γ＞0,1＜s＜2,λ(t) is the expectation of the random index N(t),t＞O.
The discovery of timescale-dependent color variability of quasars
Sun, Yu-Han; Wang, Jun-Xian; Chen, Xiao-Yang [CAS Key Laboratory for Research in Galaxies and Cosmology, Department of Astronomy, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zheng, Zhen-Ya, E-mail: sunyh92@mail.ustc.edu.cn, E-mail: jxw@ustc.edu.cn [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States)
2014-09-01
Quasars are variable on timescales from days to years in UV/optical and generally appear bluer while they brighten. The physics behind the variations in fluxes and colors remains unclear. Using Sloan Digital Sky Survey g- and r-band photometric monitoring data for quasars in Stripe 82, we find that although the flux variation amplitude increases with timescale, the color variability exhibits the opposite behavior. The color variability of quasars is prominent at timescales as short as ∼10 days, but gradually reduces toward timescales up to years. In other words, the variable emission at shorter timescales is bluer than that at longer timescales. This timescale dependence is clearly and consistently detected at all redshifts from z = 0 to 3.5; thus, it cannot be due to contamination to broadband photometry from emission lines that do not respond to fast continuum variations. The discovery directly rules out the possibility that simply attributes the color variability to contamination from a non-variable redder component such as the host galaxy. It cannot be interpreted as changes in global accretion rate either. The thermal accretion disk fluctuation model is favored in the sense that fluctuations in the inner, hotter region of the disk are responsible for short-term variations, while longer-term and stronger variations are expected from the larger and cooler disk region. An interesting implication is that one can use quasar variations at different timescales to probe disk emission at different radii.
The Discovery of Timescale-Dependent Color Variability of Quasars
Sun, Yu-Han; Chen, Xiao-Yang; Zheng, Zhen-Ya
2014-01-01
Quasars are variable on timescales from days to years in UV/optical, and generally appear bluer while they brighten. The physics behind the variations in fluxes and colors remains unclear. Using SDSS g and r band photometric monitoring data of quasars in Stripe 82, we find that although the flux variation amplitude increases with timescale, the color variability exhibits opposite behavior. The color variability of quasars is prominent at timescales as short as ~ 10 days, but gradually reduces toward timescales up to years. In other words, the variable emission at shorter timescales is bluer than that at longer timescales. This timescale dependence is clearly and consistently detected at all redshifts from z = 0 to 3.5, thus can not be due to contaminations to broadband photometry from emission lines which do not respond to fast continuum variations. The discovery directly rules out the possibility that simply attributes the color variability to contamination from a non-variable redder component, such as the h...
Qunying Wu
2016-06-01
Full Text Available Abstract In this paper, we study the complete convergence and complete moment convergence for negatively associated sequences of random variables with E X = 0 $\\mathbb{E}X=0$ , E exp ( ln α | X | 1 $\\alpha>1$ . As a result, we extend some complete convergence and complete moment convergence theorems for independent random variables to the case of negatively associated random variables without necessarily imposing any extra conditions. Our results generalize corresponding results obtained by Gut and Stadtmüller (Stat. Probab. Lett. 81:1486-1492, 2011 and Qiu and Chen (Stat. Probab. Lett. 91:76-82, 2014.
YUAN DeMei; AN Jun
2009-01-01
In this paper, we establish some Rosenthal type inequalities for maximum partial sums of asymptotically almost negatively associated random variables, which extend the corresponding results for negatively associated random variables. As applications of these inequalities, by employing the notions of residual Cesaro α-integrability and strong residual Cesaro α-integrability, we derive some results on Lp convergence where 1
random variables.
2009-01-01
In this paper, we establish some Rosenthal type inequalities for maximum partial sums of asymptotically almost negatively associated random variables, which extend the corresponding results for negatively associated random variables. As applications of these inequalities, by employing the notions of residual Cesàro α-integrability and strong residual Cesàro α-integrability, we derive some results on Lp convergence where 1 < p < 2 and complete convergence. In addition, we estimate the rate of convergence in Marcinkiewicz-Zygmund strong law for partial sums of identically distributed random variables.
On the Strong Law of Large Numbers for Non-Independent B-Valued Random Variables
Gan Shi-xin
2004-01-01
This paper investigates some conditions which imply the strong laws of large numbers for Banach space valued random variable sequences. Some generalizations of the Marcinkiewicz-Zygmund theorem and the Hoffmann-Jφrgensen and Pisier theorem are obtained.
Complete Moment Convergence for Weighted Sums of Arrays of Rowwise NA Random Variables
Dehua QIU; Pingyan CHEN
2012-01-01
In this paper we obtain some new results on complete moment convergence for weighted sums of arrays of rowwise NA random variables.Our results improve and extend some well known results from the literature.
Zero Distribution of System with Unknown Random Variables Case Study: Avoiding Collision Path
Parman Setyamartana
2014-07-01
Full Text Available This paper presents the stochastic analysis of finding the feasible trajectories of robotics arm motion at obstacle surrounding. Unknown variables are coefficients of polynomials joint angle so that the collision-free motion is achieved. ãk is matrix consisting of these unknown feasible polynomial coefficients. The pattern of feasible polynomial in the obstacle environment shows as random. This paper proposes to model the pattern of this randomness values using random polynomial with unknown variables as coefficients. The behavior of the system will be obtained from zero distribution as the characteristic of such random polynomial. Results show that the pattern of random polynomial of avoiding collision can be constructed from zero distribution. Zero distribution is like building block of the system with obstacles as uncertainty factor. By scale factor k, which has range, the random coefficient pattern can be predicted.
Random variables as pathwise integrals with respect to fractional Brownian motion
Mishura, Yuliya; Valkeila, Esko
2011-01-01
We show that a pathwise stochastic integral with respect to fractional Brownian motion with an adapted integrand $g$ can have any prescribed distribution, moreover, we give both necessary and sufficient conditions when random variables can be represented in this form. We also prove that any random variable is a value of such integral in some improper sense. We discuss some applications of these results, in particular, to fractional Black--Scholes model of financial market.
Lapko, A. V.; Lapko, V. A.; Yuronen, E. A.
2016-11-01
The new technique of testing of hypothesis of random variables independence is offered. Its basis is made by nonparametric algorithm of pattern recognition. The considered technique doesn't demand sampling of area of values of random variables.
The Sum and Difference of Two Lognormal Random Variables
C. F. Lo
2012-01-01
Full Text Available We have presented a new unified approach to model the dynamics of both the sum and difference of two correlated lognormal stochastic variables. By the Lie-Trotter operator splitting method, both the sum and difference are shown to follow a shifted lognormal stochastic process, and approximate probability distributions are determined in closed form. Illustrative numerical examples are presented to demonstrate the validity and accuracy of these approximate distributions. In terms of the approximate probability distributions, we have also obtained an analytical series expansion of the exact solutions, which can allow us to improve the approximation in a systematic manner. Moreover, we believe that this new approach can be extended to study both (1 the algebraic sum of N lognormals, and (2 the sum and difference of other correlated stochastic processes, for example, two correlated CEV processes, two correlated CIR processes, and two correlated lognormal processes with mean-reversion.
高海峰; 白广忱; 高阳; 鲍天未
2015-01-01
The fatigue life of aeroengine turbine disc presents great dispersion due to the randomness of the basic variables, such as applied load, working temperature, geometrical dimensions and material properties. In order to ameliorate reliability analysis efficiency without loss of reliability, the distributed collaborative response surface method (DCRSM) was proposed, and its basic theories were established in this work. Considering the failure dependency among the failure modes, the distributed response surface was constructed to establish the relationship between the failure mode and the relevant random variables. Then, the failure modes were considered as the random variables of system response to obtain the distributed collaborative response surface model based on structure failure criterion. Finally, the given turbine disc structure was employed to illustrate the feasibility and validity of the presented method. Through the comparison of DCRSM, Monte Carlo method (MCM) and the traditional response surface method (RSM), the results show that the computational precision for DCRSM is more consistent with MCM than RSM, while DCRSM needs far less computing time than MCM and RSM under the same simulation conditions. Thus, DCRSM is demonstrated to be a feasible and valid approach for improving the computational efficiency of reliability analysis for aeroengine turbine disc fatigue life with multiple random variables, and has great potential value for the complicated mechanical structure with multi-component and multi-failure mode.
Couso, Inés; Sánchez, Luciano
2014-01-01
This short book provides a unified view of the history and theory of random sets and fuzzy random variables, with special emphasis on its use for representing higher-order non-statistical uncertainty about statistical experiments. The authors lay bare the existence of two streams of works using the same mathematical ground, but differing form their use of sets, according to whether they represent objects of interest naturally taking the form of sets, or imprecise knowledge about such objects. Random (fuzzy) sets can be used in many fields ranging from mathematical morphology, economics, artificial intelligence, information processing and statistics per se, especially in areas where the outcomes of random experiments cannot be observed with full precision. This book also emphasizes the link between random sets and fuzzy sets with some techniques related to the theory of imprecise probabilities. This small book is intended for graduate and doctoral students in mathematics or engineering, but also provides an i...
Complete Moment Convergence of Weighted Sums for Arrays of Rowwise φ-Mixing Random Variables
Ming Le Guo
2012-01-01
Full Text Available The complete moment convergence of weighted sums for arrays of rowwise φ-mixing random variables is investigated. By using moment inequality and truncation method, the sufficient conditions for complete moment convergence of weighted sums for arrays of rowwise φ-mixing random variables are obtained. The results of Ahmed et al. (2002 are complemented. As an application, the complete moment convergence of moving average processes based on a φ-mixing random sequence is obtained, which improves the result of Kim et al. (2008.
Generating Variable and Random Schedules of Reinforcement Using Microsoft Excel Macros
Bancroft, Stacie L.; Bourret, Jason C.
2008-01-01
Variable reinforcement schedules are used to arrange the availability of reinforcement following varying response ratios or intervals of time. Random reinforcement schedules are subtypes of variable reinforcement schedules that can be used to arrange the availability of reinforcement at a constant probability across number of responses or time.…
Modelling the statistical dependence of rainfall event variables by a trivariate copula function
M. Balistrocchi
2011-01-01
Full Text Available In many hydrological models, such as those derived by analytical probabilistic methods, the precipitation stochastic process is represented by means of individual storm random variables which are supposed to be independent of each other. However, several proposals were advanced to develop joint probability distributions able to account for the observed statistical dependence. The traditional technique of the multivariate statistics is nevertheless affected by several drawbacks, whose most evident issue is the unavoidable subordination of the dependence structure assessment to the marginal distribution fitting. Conversely, the copula approach can overcome this limitation, by splitting the problem in two distinct items. Furthermore, goodness-of-fit tests were recently made available and a significant improvement in the function selection reliability has been achieved. Herein a trivariate probability distribution of the rainfall event volume, the wet weather duration and the interevent time is proposed and verified by test statistics with regard to three long time series recorded in different Italian climates. The function was developed by applying a mixing technique to bivariate copulas, which were formerly obtained by analyzing the random variables in pairs. A unique probabilistic model seems to be suitable for representing the dependence structure, despite the sensitivity shown by the dependence parameters towards the threshold utilized in the procedure for extracting the independent events. The joint probability function was finally developed by adopting a Weibull model for the marginal distributions.
Epoch-dependent absorption line profile variability in lambda Cep
Uuh-Sonda, J M; Eenens, P; Mahy, L; Palate, M; Gosset, E; Flores, C A
2014-01-01
We present the analysis of a multi-epoch spectroscopic monitoring campaign of the O6Ief star lambda Cep. Previous observations reported the existence of two modes of non-radial pulsations in this star. Our data reveal a much more complex situation. The frequency content of the power spectrum considerably changes from one epoch to the other. We find no stable frequency that can unambiguously be attributed to pulsations. The epoch-dependence of the frequencies and variability patterns are similar to what is seen in the wind emission lines of this and other Oef stars, suggesting that both phenomena likely have the same, currently still unknown, origin.
Variable Selection for Varying-Coefficient Models with Missing Response at Random
Pei Xin ZHAO; Liu Gen XUE
2011-01-01
In this paper, we present a variable selection procedure by combining basis function approximations with penalized estimating equations for varying-coefficient models with missing response at random. With appropriate selection of the tuning parameters, we establish the consistency of the variable selection procedure and the optimal convergence rate of the regularized estimators. A simulation study is undertaken to assess the finite sample performance of the proposed variable selection procedure.
Hörning, Sebastian; Bárdossy, András
2016-04-01
Traditional geostatistical analysis is mainly based on variograms and/or covariance functions. A more advanced investigation of spatially distributed variables can be performed using rank order geostatistical methods. For example the rank correlation function in combination with the asymmetry function gives a more detailed insight in the spatial dependence structure of the data of interest. However, many physical processes, for example advection of solute in porous media, can lead to asymmetries that exhibit a certain direction, i.e. they lead to irreversibility in a spatial context. Reversibility is well known in time series analysis; however it is hardly utilized in geostatistics. Spatial reversibility or directional dependencies can neither be covered by the rank correlation function nor by the classical asymmetry function. Therefore, a statistical test based on a chi-squared test on empirical directional copulas will be introduced that enables testing for spatial reversibility. In order to quantify the strength of directional dependencies a new direction-dependent asymmetry function is introduced. Different examples, ranging from synthetical flow and transport experiments to real-world precipitation data, will be used to demonstrate the applicability of the test and the new measure. The difference to classical anisotropy will be shown and the chi-squared test will also be used to test for significance.
On the use of fractional calculus for the probabilistic characterization of random variables
Cottone, Giulio; 10.1016/j.probengmech.2008.08.002
2013-01-01
In this paper, the classical problem of the probabilistic characterization of a random variable is re-examined. A random variable is usually described by the probability density function (PDF) or by its Fourier transform, namely the characteristic function (CF). The CF can be further expressed by a Taylor series involving the moments of the random variable. However, in some circumstances, the moments do not exist and the Taylor expansion of the CF is useless. This happens for example in the case of $\\alpha$--stable random variables. Here, the problem of representing the CF or the PDF of random variables (r.vs) is examined by introducing fractional calculus. Two very remarkable results are obtained. Firstly, it is shown that the fractional derivatives of the CF in zero coincide with fractional moments. This is true also in case of CF not derivable in zero (like the CF of $\\alpha$--stable r.vs). Moreover, it is shown that the CF may be represented by a generalized Taylor expansion involving fractional moments. ...
Convergence properties of polynomial chaos approximations for L2 random variables.
Field, Richard V., Jr. (.,; .); Grigoriu, Mircea (Cornell University, Ithaca, NY)
2007-03-01
Polynomial chaos (PC) representations for non-Gaussian random variables are infinite series of Hermite polynomials of standard Gaussian random variables with deterministic coefficients. For calculations, the PC representations are truncated, creating what are herein referred to as PC approximations. We study some convergence properties of PC approximations for L{sub 2} random variables. The well-known property of mean-square convergence is reviewed. Mathematical proof is then provided to show that higher-order moments (i.e., greater than two) of PC approximations may or may not converge as the number of terms retained in the series, denoted by n, grows large. In particular, it is shown that the third absolute moment of the PC approximation for a lognormal random variable does converge, while moments of order four and higher of PC approximations for uniform random variables do not converge. It has been previously demonstrated through numerical study that this lack of convergence in the higher-order moments can have a profound effect on the rate of convergence of the tails of the distribution of the PC approximation. As a result, reliability estimates based on PC approximations can exhibit large errors, even when n is large. The purpose of this report is not to criticize the use of polynomial chaos for probabilistic analysis but, rather, to motivate the need for further study of the efficacy of the method.
Effect of methamphetamine dependence on heart rate variability.
Henry, Brook L; Minassian, Arpi; Perry, William
2012-05-01
Methamphetamine (METH) is an increasing popular and highly addictive stimulant associated with autonomic nervous system (ANS) dysfunction, cardiovascular pathology and neurotoxicity. Heart rate variability (HRV) has been used to assess autonomic function and predict mortality in cardiac disorders and drug intoxication, but has not been characterized in METH use. We recorded HRV in a sample of currently abstinent individuals with a history of METH dependence compared to age- and gender-matched drug-free comparison subjects. HRV was assessed using time domain, frequency domain, and non-linear entropic analyses in 17 previously METH-dependent and 21 drug-free comparison individuals during a 5 minute rest period. The METH-dependent group demonstrated significant reduction in HRV, reduced parasympathetic activity, and diminished heartbeat complexity relative to comparison participants. More recent METH use was associated with increased sympathetic tone. Chronic METH exposure may be associated with decreased HRV, impaired vagal function, and reduction in heart rate complexity as assessed by multiple methods of analysis. We discuss and review evidence that impaired HRV may be related to the cardiotoxic or neurotoxic effects of prolonged METH use.
CONVERGENCE RATES IN THE STRONG LAWS FOR A CLASS OF DEPENDENT RANDOM FIFLDS
CaiGuanghui
2003-01-01
By using a Rosenthal type inequality established in this paper,the complete convergence rates in the strong laws for a class of dependent random fields are discussed.And the result obtained extends those for ρ--mixing random fields,ρ*-mixing random fields and negatively associated fields.
A Particle Swarm Optimization Algorithm with Variable Random Functions and Mutation
ZHOU Xiao-Jun; YANG Chun-Hua; GUI Wei-Hua; DONG Tian-Xue
2014-01-01
The convergence analysis of the standard particle swarm optimization (PSO) has shown that the changing of random functions, personal best and group best has the potential to improve the performance of the PSO. In this paper, a novel strategy with variable random functions and polynomial mutation is introduced into the PSO, which is called particle swarm optimization algorithm with variable random functions and mutation (PSO-RM). Random functions are adjusted with the density of the population so as to manipulate the weight of cognition part and social part. Mutation is executed on both personal best particle and group best particle to explore new areas. Experiment results have demonstrated the effectiveness of the strategy.
Autoclassification of the Variable 3XMM Sources Using the Random Forest Machine Learning Algorithm
Farrell, Sean A; Lo, Kitty K
2015-01-01
In the current era of large surveys and massive data sets, autoclassification of astrophysical sources using intelligent algorithms is becoming increasingly important. In this paper we present the catalog of variable sources in the Third XMM-Newton Serendipitous Source catalog (3XMM) autoclassified using the Random Forest machine learning algorithm. We used a sample of manually classified variable sources from the second data release of the XMM-Newton catalogs (2XMMi-DR2) to train the classifier, obtaining an accuracy of ~92%. We also evaluated the effectiveness of identifying spurious detections using a sample of spurious sources, achieving an accuracy of ~95%. Manual investigation of a random sample of classified sources confirmed these accuracy levels and showed that the Random Forest machine learning algorithm is highly effective at automatically classifying 3XMM sources. Here we present the catalog of classified 3XMM variable sources. We also present three previously unidentified unusual sources that wer...
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'.
Wright, Marvin N; Dankowski, Theresa; Ziegler, Andreas
2017-04-15
The most popular approach for analyzing survival data is the Cox regression model. The Cox model may, however, be misspecified, and its proportionality assumption may not always be fulfilled. An alternative approach for survival prediction is random forests for survival outcomes. The standard split criterion for random survival forests is the log-rank test statistic, which favors splitting variables with many possible split points. Conditional inference forests avoid this split variable selection bias. However, linear rank statistics are utilized by default in conditional inference forests to select the optimal splitting variable, which cannot detect non-linear effects in the independent variables. An alternative is to use maximally selected rank statistics for the split point selection. As in conditional inference forests, splitting variables are compared on the p-value scale. However, instead of the conditional Monte-Carlo approach used in conditional inference forests, p-value approximations are employed. We describe several p-value approximations and the implementation of the proposed random forest approach. A simulation study demonstrates that unbiased split variable selection is possible. However, there is a trade-off between unbiased split variable selection and runtime. In benchmark studies of prediction performance on simulated and real datasets, the new method performs better than random survival forests if informative dichotomous variables are combined with uninformative variables with more categories and better than conditional inference forests if non-linear covariate effects are included. In a runtime comparison, the method proves to be computationally faster than both alternatives, if a simple p-value approximation is used. Copyright © 2017 John Wiley & Sons, Ltd.
Efficient Estimation of Mutual Information for Strongly Dependent Variables
Gao, Shuyang; Galstyan, Aram
2014-01-01
We demonstrate that a popular class of nonparametric mutual information (MI) estimators based on k-nearest-neighbor graphs requires number of samples that scales exponentially with the true MI. Consequently, accurate estimation of MI between two strongly dependent variables is possible only for prohibitively large sample size. This important yet overlooked shortcoming of the existing estimators is due to their implicit reliance on local uniformity of the underlying joint distribution. We introduce a new estimator that is robust to local non-uniformity, works well with limited data, and is able to capture relationship strengths over many orders of magnitude. We demonstrate the superior performance of the proposed estimator on both synthetic and real-world data.
New Alphabet-Dependent Morphological Transition in Random RNA Alignment
Valba, O. V.; Tamm, M. V.; Nechaev, S. K.
2012-07-01
We study the fraction f of nucleotides involved in the formation of a cactuslike secondary structure of random heteropolymer RNA-like molecules. In the low-temperature limit, we study this fraction as a function of the number c of different nucleotide species. We show, that with changing c, the secondary structures of random RNAs undergo a morphological transition: f(c)→1 for c≤ccr as the chain length n goes to infinity, signaling the formation of a virtually perfect gapless secondary structure; while f(c)ccr, which means that a nonperfect structure with gaps is formed. The strict upper and lower bounds 2≤ccr≤4 are proven, and the numerical evidence for ccr is presented. The relevance of the transition from the evolutional point of view is discussed.
A note on strong law of large numbers of random variables
LIN Zheng-yan; SHEN Xin-mei
2006-01-01
In this paper, the Chung's strong law of large numbers is generalized to the random variables which do not need the condition of independence, while the sequence of Borel functions verifies some conditions weaker than that in Chung's theorem.Some convergence theorems for martingale difference sequence such as Lp martingale difference sequence are the particular cases of results achieved in this paper. Finally, the convergence theorem for A-summability of sequence of random variables is proved,where A is a suitable real infinite matrix.
Exponential inequalities for associated random variables and strong laws of large numbers
2007-01-01
Some exponential inequalities for partial sums of associated random variables are established. These inequalities improve the corresponding results obtained by Ioannides and Roussas (1999), and Oliveira (2005). As application, some strong laws of large numbers are given. For the case of geometrically decreasing covariances, we obtain the rate of convergence n-1/2(log log n)1/2(logn) which is close to the optimal achievable convergence rate for independent random variables under an iterated logarithm, while Ioannides and Roussas (1999), and Oliveira (2005) only got n-1/3(logn)2/3 and n-1/3(logn)5/3, separately.
Exponential inequalities for associated random variables and strong laws of large numbers
Shan-chao YANG; Min CHEN
2007-01-01
Some exponential inequalities for partial sums of associated random variables are established. These inequalities improve the corresponding results obtained by Ioannides and Roussas (1999), and Oliveira (2005). As application, some strong laws of large numbers are given. For the case of geometrically decreasing covariances, we obtain the rate of convergence n-1/2(log log n)1/2(log n) which is close to the optimal achievable convergence rate for independent random variables under an iterated logarithm, while Ioannides and Roussas (1999), and Oliveira (2005) only got n-1/3 (log n)2/3 and n-1/3 (log n)5/3, separately.
Complete Convergence of Weighted Sums for ρ*-Mixing Sequence of Random Variables
Mingle GUO; Dongjin ZHU
2013-01-01
In this paper,the complete convergence of weighted sums for ρ*-mixing sequence of random variables is investigated.By applying moment inequality and truncation methods,the equivalent conditions of complete convergence of weighted sums for ρ*-mixing sequence of random variables are established.We not only promote and improve the results of Li et al.(J.Theoret.Probab.,1995,8(1):49-76) from i.i.d.to ρ*-mixing setting but also obtain their necessities and relax their conditions.
Dependence of NAO variability on coupling with sea ice
Strong, Courtenay; Magnusdottir, Gudrun
2011-05-01
The variance of the North Atlantic Oscillation index (denoted N) is shown to depend on its coupling with area-averaged sea ice concentration anomalies in and around the Barents Sea (index denoted B). The observed form of this coupling is a negative feedback whereby positive N tends to produce negative B, which in turn forces negative N. The effects of this feedback in the system are examined by modifying the feedback in two modeling frameworks: a statistical vector autoregressive model ( F VAR) and an atmospheric global climate model ( F CAM) customized so that sea ice anomalies on the lower boundary are stochastic with adjustable sensitivity to the model's evolving N. Experiments show that the variance of N decreases nearly linearly with the sensitivity of B to N, where the sensitivity is a measure of the negative feedback strength. Given that the sea ice concentration field has anomalies, the variance of N goes down as these anomalies become more sensitive to N. If the sea ice concentration anomalies are entirely absent, the variance of N is even smaller than the experiment with the most sensitive anomalies. Quantifying how the variance of N depends on the presence and sensitivity of sea ice anomalies to N has implications for the simulation of N in global climate models. In the physical system, projected changes in sea ice thickness or extent could alter the sensitivity of B to N, impacting the within-season variability and hence predictability of N.
Zheng, Zhong; Hämäläinen, Jyri; Tirkkonen, Olav
2012-01-01
We derive a closed-form expression for the orthogonal polynomials associated with the general lognormal density. The result can be utilized to construct easily computable approximations for probability density function of a product of random variables. As an example, we have calculated the approximative distribution for the product of correlated Nakagami-m variables. Simulations indicate that accuracy of the proposed approximation is good.
USING RANDOM PROPORTIONAL PULSE FEEDBACK OF SYSTEM VARIABLES TO CONTROL CHAOS AND HYPERCHAOS
LUO XIAO-SHU; WANG BING-HONG; GAO YUAN; JIANG FENG
2001-01-01
A method that allows one to control chaotic and hyperchaotic systems by a random proportional pulse feedback of system variables is proposed. This method is illustrated with the Rossler chaotic and the complex Lorenz-Harken hyperchaotic systems, and a better control result is obtained. The advantage of this method is that just one perturbed system variable is enough to obtain a stabilized periodic orbit.
Size dependence of the largest distance between random points
Krawczyk, Malgorzata J; Kulakowski, Krzysztof
2013-01-01
A set of $N$ points is chosen randomly in a $D$-dimensional volume $V=a^D$, with periodic boundary conditions. For each point $i$, its distance $d_i$ is found to its nearest neighbour. Then, the maximal value is found, $d_{max}=max(d_i, i=1,...,N)$. Our numerical calculations indicate, that when the density $N/V$=const, $d_{max}$ scales with the linear system size as $d^2_{max}\\propto a^\\phi$, with $\\phi=0.24\\pm0.04$ for $D=1,2,3,4$.
van der Zwan, J.E.; de Vente, W.; Huizink, A.C.; Bögels, S.M.; de Bruin, E.I.
2015-01-01
In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing
A NONCLASSICAL LAW OF ITERATED LOGARITHM FOR NEGATIVELY ASSOCIATED RANDOM VARIABLES
JiangYe
2003-01-01
A nonclassical law of iterated logarithm that holds for a stationary negatively associated sequence of random variables with finite variance is proved in this paper.The proof is based on a Rosenthal type maximal inequality and the subsequence method.This result extends the work of Klesov,Rosalsky(2001)and Shao.Su(1999).
2008-01-01
In this paper,we prove a general law of the iterated logarithm (LIL) for independent non-identically distributed B-valued random variables.As an interesting application,we obtain the law of the iterated logarithm for the empirical covariance of Hilbertian autoregressive processes.
On Complete Convergence for Arrays of Rowwise Strong Mixing Random Variables
ZHOU XING-CAI; LIN JIN-GUAN; WANG XUE-JUN; HU SHU-HE
2011-01-01
In this paper,we present a general method to prove the complete convergence for arrays of rowwise strong mixing random variables,and give some results on complete convergence under some suitable conditions.Some Marcinkiewicz-Zygmund type strong laws of large numbers are also obtained.
Laws of Large Numbers of Negatively Correlated Random Variables for Capacities
Wen-juan LI; Zeng-jing CHEN
2011-01-01
Our aim is to present some limit theorems for capacities.We consider a sequence of pairwise negatively correlated random variables.We obtain laws of large numbers for upper probabilities and 2-aiternating capacities,using some results in the classical probability theory and a non-additive version of Chebyshev's inequality and Borai-Contelli lemma for capacities.
Bounds for right tails of deterministic and stochastic sums of random variables
G. Darkiewicz; G. Deelstra; J. Dhaene; T. Hoedemakers; M. Vanmaele
2009-01-01
We investigate lower and upper bounds for right tails (stop-loss premiums) of deterministic and stochastic sums of nonindependent random variables. The bounds are derived using the concepts of comonotonicity, convex order, and conditioning. The performance of the presented approximations is investig
Eisinga, R.N.; Grotenhuis, H.F. te; Pelzer, B.J.
2013-01-01
We discuss saddlepoint approximations to the distribution of the sum of independent non-identically distributed binomial random variables. We examine the accuracy of the saddlepoint methods for a sum of 10 binomials with different sets of parameter values. The numerical results indicate that the sad
Oracle Efficient Variable Selection in Random and Fixed Effects Panel Data Models
Kock, Anders Bredahl
This paper generalizes the results for the Bridge estimator of Huang et al. (2008) to linear random and fixed effects panel data models which are allowed to grow in both dimensions. In particular we show that the Bridge estimator is oracle efficient. It can correctly distinguish between relevant...... and irrelevant variables and the asymptotic distribution of the estimators of the coefficients of the relevant variables is the same as if only these had been included in the model, i.e. as if an oracle had revealed the true model prior to estimation. In the case of more explanatory variables than observations...
Stotland, Alexander; Peer, Tal; Cohen, Doron [Department of Physics, Ben-Gurion University, Beer-Sheva 84005 (Israel); Budoyo, Rangga; Kottos, Tsampikos [Department of Physics, Wesleyan University, Middletown, CT 06459 (United States)
2008-07-11
The calculation of the conductance of disordered rings requires a theory that goes beyond the Kubo-Drude formulation. Assuming 'mesoscopic' circumstances the analysis of the electro-driven transitions shows similarities with a percolation problem in energy space. We argue that the texture and the sparsity of the perturbation matrix dictate the value of the conductance, and study its dependence on the disorder strength, ranging from the ballistic to the Anderson localization regime. An improved sparse random matrix model is introduced to capture the essential ingredients of the problem, and leads to a generalized variable range hopping picture. (fast track communication)
Cluster-size dependent randomization traffic flow model
Gao Kun; Wang Bing-Hong; Fu Chuan-Ji; Lu Yu-Feng
2007-01-01
In order to exhibit the meta-stable states, several slow-to-start rules have been investigated as modification to Nagel-Schreckenberg (NS) model. These models can reproduce some realistic phenomena which are absent in the original NS model. But in these models, the size of cluster is still not considered as a useful parameter. In real traffic,the slow-to-start motion of a standing vehicle often depends on the degree of congestion which can be measured by the clusters'size. According to this idea, we propose a cluster-size dependent slow-to-start model based on the speeddependent slow-to-start rule (VDR) model. It gives expected results through simulations. Comparing with the VDR model, our new model has a better traffic efficiency and shows richer complex characters.
El-Wakil, S. A.; Sallah, M.; El-Hanbaly, A. M.
2015-10-01
The stochastic radiative transfer problem is studied in a participating planar finite continuously fluctuating medium. The problem is considered for specular- and diffusly-reflecting boundaries with linear anisotropic scattering. Random variable transformation (RVT) technique is used to get the complete average for the solution functions, that are represented by the probability-density function (PDF) of the solution process. In the RVT algorithm, a simple integral transformation to the input stochastic process (the extinction function of the medium) is applied. This linear transformation enables us to rewrite the stochastic transport equations in terms of the optical random variable (x) and the optical random thickness (L). Then the transport equation is solved deterministically to get a closed form for the solution as a function of x and L. So, the solution is used to obtain the PDF of the solution functions applying the RVT technique among the input random variable (L) and the output process (the solution functions). The obtained averages of the solution functions are used to get the complete analytical averages for some interesting physical quantities, namely, reflectivity and transmissivity at the medium boundaries. In terms of the average reflectivity and transmissivity, the average of the partial heat fluxes for the generalized problem with internal source of radiation are obtained and represented graphically.
Handling Time-dependent Variables : Antibiotics and Antibiotic Resistance
Munoz-Price, L. Silvia; Frencken, Jos F.; Tarima, Sergey; Bonten, Marc
2016-01-01
Elucidating quantitative associations between antibiotic exposure and antibiotic resistance development is important. In the absence of randomized trials, observational studies are the next best alternative to derive such estimates. Yet, as antibiotics are prescribed for varying time periods, antibi
A Realization of a Quasi-Random Walk for Atoms in Time-Dependent Optical Potentials
Torsten Hinkel
2015-09-01
Full Text Available We consider the time dependent dynamics of an atom in a two-color pumped cavity, longitudinally through a side mirror and transversally via direct driving of the atomic dipole. The beating of the two driving frequencies leads to a time dependent effective optical potential that forces the atom into a non-trivial motion, strongly resembling a discrete random walk behavior between lattice sites. We provide both numerical and analytical analysis of such a quasi-random walk behavior.
Xin-Fan Wang
2013-01-01
Full Text Available We investigate the dynamic stochastic multicriteria decision making (SMCDM problems, in which the criterion values take the form of log-normally distributed random variables, and the argument information is collected from different periods. We propose two new geometric aggregation operators, such as the log-normal distribution weighted geometric (LNDWG operator and the dynamic log-normal distribution weighted geometric (DLNDWG operator, and develop a method for dynamic SMCDM with log-normally distributed random variables. This method uses the DLNDWG operator and the LNDWG operator to aggregate the log-normally distributed criterion values, utilizes the entropy model of Shannon to generate the time weight vector, and utilizes the expectation values and variances of log-normal distributions to rank the alternatives and select the best one. Finally, an example is given to illustrate the feasibility and effectiveness of this developed method.
无
2005-01-01
The character and an algorithm about DRVIP(discrete random variable with interval probability) and the second kind DRVFP (discrete random variable with crisp event-fuzzy probability) are researched. Using the fuzzy resolution theorem, the solving mathematical expectation of a DRVFP can be translated into solving mathematical expectation of a series of RVIP. It is obvious that solving mathematical expectation of a DRVIP is a typical linear programming problem. A very functional calculating formula for solving mathematical expectation of DRVIP was obtained by using the Dantzig's simplex method. The example indicates that the result obtained by using the functional calculating formula fits together completely with the result obtained by using the linear programming method, but the process using the formula deduced is simpler.
Wang, Xin-Fan; Wang, Jian-Qiang; Deng, Sheng-Yue
2013-01-01
We investigate the dynamic stochastic multicriteria decision making (SMCDM) problems, in which the criterion values take the form of log-normally distributed random variables, and the argument information is collected from different periods. We propose two new geometric aggregation operators, such as the log-normal distribution weighted geometric (LNDWG) operator and the dynamic log-normal distribution weighted geometric (DLNDWG) operator, and develop a method for dynamic SMCDM with log-normally distributed random variables. This method uses the DLNDWG operator and the LNDWG operator to aggregate the log-normally distributed criterion values, utilizes the entropy model of Shannon to generate the time weight vector, and utilizes the expectation values and variances of log-normal distributions to rank the alternatives and select the best one. Finally, an example is given to illustrate the feasibility and effectiveness of this developed method.
Tetschke, F; Schneider, U; Schleussner, E; Witte, O W; Hoyer, D
2016-03-01
Fetal maturation age assessment based on heart rate variability (HRV) is a predestinated tool in prenatal diagnosis. To date, almost linear maturation characteristic curves are used in univariate and multivariate models. Models using complex multivariate maturation characteristic curves are pending. To address this problem, we use Random Forest (RF) to assess fetal maturation age and compare RF with linear, multivariate age regression. We include previously developed HRV indices such as traditional time and frequency domain indices and complexity indices of multiple scales. We found that fetal maturation was best assessed by complexity indices of short scales and skewness in state-dependent datasets (quiet sleep, active sleep) as well as in state-independent recordings. Additionally, increasing fluctuation amplitude contributed to the model in the active sleep state. None of the traditional linear HRV parameters contributed to the RF models. Compared to linear, multivariate regression, the mean prediction of gestational age (GA) is more accurate with RF than in linear, multivariate regression (quiet state: R(2)=0,617 vs. R(2)=0,461, active state: R(2)=0,521 vs. R(2)=0,436, state independent: R(2)=0,583 vs. R(2)=0,548). We conclude that classification and regression tree models such as RF methodology are appropriate for the evaluation of fetal maturation age. The decisive role of adjustments between different time scales of complexity may essentially extend previous analysis concepts mainly based on rhythms and univariate complexity indices. Those system characteristics may have implication for better understanding and accessibility of the maturating complex autonomic control and its disturbance.
On the complete convergence for weighted sums of a class of random variables
Jinghuan Zhao
2016-09-01
Full Text Available Abstract In this article, some new results as regards complete convergence for weighted sums ∑ i = 1 n a n i X i $\\sum_{i=1}^{n}a_{ni}X_{i}$ of random variables satisfying the Rosenthal type inequality are established under some mild conditions. These results extend the corresponding theorems of Deng et al. (Filomat 28(3:509-522, 2014 and Gan and Chen (Acta Math. Sci. 28(2:269-281, 2008.
St. Martin, Clara M.; Lundquist, Julie K.; Handschy, Mark A.
2015-04-01
The variability in wind-generated electricity complicates the integration of this electricity into the electrical grid. This challenge steepens as the percentage of renewably-generated electricity on the grid grows, but variability can be reduced by exploiting geographic diversity: correlations between wind farms decrease as the separation between wind farms increases. But how far is far enough to reduce variability? Grid management requires balancing production on various timescales, and so consideration of correlations reflective of those timescales can guide the appropriate spatial scales of geographic diversity grid integration. To answer ‘how far is far enough,’ we investigate the universal behavior of geographic diversity by exploring wind-speed correlations using three extensive datasets spanning continents, durations and time resolution. First, one year of five-minute wind power generation data from 29 wind farms span 1270 km across Southeastern Australia (Australian Energy Market Operator). Second, 45 years of hourly 10 m wind-speeds from 117 stations span 5000 km across Canada (National Climate Data Archive of Environment Canada). Finally, four years of five-minute wind-speeds from 14 meteorological towers span 350 km of the Northwestern US (Bonneville Power Administration). After removing diurnal cycles and seasonal trends from all datasets, we investigate dependence of correlation length on time scale by digitally high-pass filtering the data on 0.25-2000 h timescales and calculating correlations between sites for each high-pass filter cut-off. Correlations fall to zero with increasing station separation distance, but the characteristic correlation length varies with the high-pass filter applied: the higher the cut-off frequency, the smaller the station separation required to achieve de-correlation. Remarkable similarities between these three datasets reveal behavior that, if universal, could be particularly useful for grid management. For high
The effect of cluster size variability on statistical power in cluster-randomized trials.
Stephen A Lauer
Full Text Available The frequency of cluster-randomized trials (CRTs in peer-reviewed literature has increased exponentially over the past two decades. CRTs are a valuable tool for studying interventions that cannot be effectively implemented or randomized at the individual level. However, some aspects of the design and analysis of data from CRTs are more complex than those for individually randomized controlled trials. One of the key components to designing a successful CRT is calculating the proper sample size (i.e. number of clusters needed to attain an acceptable level of statistical power. In order to do this, a researcher must make assumptions about the value of several variables, including a fixed mean cluster size. In practice, cluster size can often vary dramatically. Few studies account for the effect of cluster size variation when assessing the statistical power for a given trial. We conducted a simulation study to investigate how the statistical power of CRTs changes with variable cluster sizes. In general, we observed that increases in cluster size variability lead to a decrease in power.
Extended q-Gaussian and q-exponential distributions from gamma random variables.
Budini, Adrián A
2015-05-01
The family of q-Gaussian and q-exponential probability densities fit the statistical behavior of diverse complex self-similar nonequilibrium systems. These distributions, independently of the underlying dynamics, can rigorously be obtained by maximizing Tsallis "nonextensive" entropy under appropriate constraints, as well as from superstatistical models. In this paper we provide an alternative and complementary scheme for deriving these objects. We show that q-Gaussian and q-exponential random variables can always be expressed as a function of two statistically independent gamma random variables with the same scale parameter. Their shape index determines the complexity q parameter. This result also allows us to define an extended family of asymmetric q-Gaussian and modified q-exponential densities, which reduce to the standard ones when the shape parameters are the same. Furthermore, we demonstrate that a simple change of variables always allows relating any of these distributions with a beta stochastic variable. The extended distributions are applied in the statistical description of different complex dynamics such as log-return signals in financial markets and motion of point defects in a fluid flow.
An efficient hybrid reliability analysis method with random and interval variables
Xie, Shaojun; Pan, Baisong; Du, Xiaoping
2016-09-01
Random and interval variables often coexist. Interval variables make reliability analysis much more computationally intensive. This work develops a new hybrid reliability analysis method so that the probability analysis (PA) loop and interval analysis (IA) loop are decomposed into two separate loops. An efficient PA algorithm is employed, and a new efficient IA method is developed. The new IA method consists of two stages. The first stage is for monotonic limit-state functions. If the limit-state function is not monotonic, the second stage is triggered. In the second stage, the limit-state function is sequentially approximated with a second order form, and the gradient projection method is applied to solve the extreme responses of the limit-state function with respect to the interval variables. The efficiency and accuracy of the proposed method are demonstrated by three examples.
Jensen, J.L.
1993-01-01
Previous results on Edgeworth expansions for sums over a random field are extended to the case where the strong mixing coefficient depends not only on the distance between two sets of random variables, but also on the size of the two sets. The results are applied to the Poisson and the Strauss po...... point processes, giving rise also to local limit results. © 1993 The Institute of Statistical Mathematics....
Krøigård, Thomas; Gaist, David; Otto, Marit; Højlund, Dorthe; Selmar, Peter E; Sindrup, Søren H
2014-08-01
The reproducibility of variables commonly included in studies of peripheral nerve conduction in healthy individuals has not previously been analyzed using a random effects regression model. We examined the temporal changes and variability of standard nerve conduction measures in the leg. Peroneal nerve distal motor latency, motor conduction velocity, and compound motor action potential amplitude; sural nerve sensory action potential amplitude and sensory conduction velocity; and tibial nerve minimal F-wave latency were examined in 51 healthy subjects, aged 40 to 67 years. They were reexamined after 2 and 26 weeks. There was no change in the variables except for a minor decrease in sural nerve sensory action potential amplitude and a minor increase in tibial nerve minimal F-wave latency. Reproducibility was best for peroneal nerve distal motor latency and motor conduction velocity, sural nerve sensory conduction velocity, and tibial nerve minimal F-wave latency. Between-subject variability was greater than within-subject variability. Sample sizes ranging from 21 to 128 would be required to show changes twice the magnitude of the spontaneous changes observed in this study. Nerve conduction studies have a high reproducibility, and variables are mainly unaltered during 6 months. This study provides a solid basis for the planning of future clinical trials assessing changes in nerve conduction.
Correchel Vladia
2005-01-01
Full Text Available The precision of the 137Cs fallout redistribution technique for the evaluation of soil erosion rates is strongly dependent on the quality of an average inventory taken at a representative reference site. The knowledge of the sources and of the degree of variation of the 137Cs fallout spatial distribution plays an important role on its use. Four reference sites were selected in the South-Central region of Brazil which were characterized in terms of soil chemical, physical and mineralogical aspects as well as the spatial variability of 137Cs inventories. Some important differences in the patterns of 137Cs depth distribution in the soil profiles of the different sites were found. They are probably associated to chemical, physical, mineralogical and biological differences of the soils but many questions still remain open for future investigation, mainly those regarding the adsorption and dynamics of the 137Cs ions in soil profiles under tropical conditions. The random spatial variability (inside each reference site was higher than the systematic spatial variability (between reference sites but their causes were not clearly identified as possible consequences of chemical, physical, mineralogical variability, and/or precipitation.
Effects of cell-cycle-dependent expression on random fluctuations in protein levels.
Soltani, Mohammad; Singh, Abhyudai
2016-12-01
Expression of many genes varies as a cell transitions through different cell-cycle stages. How coupling between stochastic expression and cell cycle impacts cell-to-cell variability (noise) in the level of protein is not well understood. We analyse a model where a stable protein is synthesized in random bursts, and the frequency with which bursts occur varies within the cell cycle. Formulae quantifying the extent of fluctuations in the protein copy number are derived and decomposed into components arising from the cell cycle and stochastic processes. The latter stochastic component represents contributions from bursty expression and errors incurred during partitioning of molecules between daughter cells. These formulae reveal an interesting trade-off: cell-cycle dependencies that amplify the noise contribution from bursty expression also attenuate the contribution from partitioning errors. We investigate the existence of optimum strategies for coupling expression to the cell cycle that minimize the stochastic component. Intriguingly, results show that a zero production rate throughout the cell cycle, with expression only occurring just before cell division, minimizes noise from bursty expression for a fixed mean protein level. By contrast, the optimal strategy in the case of partitioning errors is to make the protein just after cell division. We provide examples of regulatory proteins that are expressed only towards the end of the cell cycle, and argue that such strategies enhance robustness of cell-cycle decisions to the intrinsic stochasticity of gene expression.
An, Xin; Xu, Shuo; Zhang, Lu-Da; Su, Shi-Guang
2009-01-01
In the present paper, on the basis of LS-SVM algorithm, we built a multiple dependent variables LS-SVM (MLS-SVM) regression model whose weights can be optimized, and gave the corresponding algorithm. Furthermore, we theoretically explained the relationship between MLS-SVM and LS-SVM. Sixty four broomcorn samples were taken as experimental material, and the sample ratio of modeling set to predicting set was 51 : 13. We first selected randomly and uniformly five weight groups in the interval [0, 1], and then in the way of leave-one-out (LOO) rule determined one appropriate weight group and parameters including penalizing parameters and kernel parameters in the model according to the criterion of the minimum of average relative error. Then a multiple dependent variables quantitative analysis model was built with NIR spectrum and simultaneously analyzed three chemical constituents containing protein, lysine and starch. Finally, the average relative errors between actual values and predicted ones by the model of three components for the predicting set were 1.65%, 6.47% and 1.37%, respectively, and the correlation coefficients were 0.9940, 0.8392 and 0.8825, respectively. For comparison, LS-SVM was also utilized, for which the average relative errors were 1.68%, 6.25% and 1.47%, respectively, and the correlation coefficients were 0.9941, 0.8310 and 0.8800, respectively. It is obvious that MLS-SVM algorithm is comparable to LS-SVM algorithm in modeling analysis performance, and both of them can give satisfying results. The result shows that the model with MLS-SVM algorithm is capable of doing multi-components NIR quantitative analysis synchronously. Thus MLS-SVM algorithm offers a new multiple dependent variables quantitative analysis approach for chemometrics. In addition, the weights have certain effect on the prediction performance of the model with MLS-SVM, which is consistent with our intuition and is validated in this study. Therefore, it is necessary to optimize
Vijaya M Musini
Full Text Available Systematic reviews can often reveal much more than the original objective of the work. The objectives of this retrospective analysis were to answer three basic questions about blood pressure variability: 1 Does blood pressure entry criterion have an effect on baseline blood pressure variability? 2 Do thiazide diuretics have a significant effect on blood pressure variability? and 3 Does systolic blood pressure vary to the same degree as diastolic blood pressure? This analysis of blood pressure variability is based on resting standardized research setting BP readings from two systematic reviews evaluating blood pressure lowering efficacy of thiazide diuretics from double blind randomized controlled trials in 33,611 patients with primary hypertension. The standard deviation reported in trials was the focus of the research and the unit of analysis. When a threshold systolic or diastolic blood pressure value is used to determine entry into a trial, baseline variability is significantly decreased, systolic from 14.0 to 9.3 mmHg and diastolic from 8.4 to 5.3 mmHg. Thiazides do not change BP variability as the standard deviation and coefficient of variation of systolic blood pressure and diastolic blood pressure did not differ between thiazide and placebo groups at end of treatment. The coefficient of variation of systolic blood pressure was significantly greater than the coefficient of variation of diastolic blood pressure. Entry criterion decreases the baseline blood pressure variability. Treatment with a thiazide diuretic does not affect blood pressure variability. Systolic blood pressure varies to a greater degree than diastolic blood pressure.
The Timescale-dependent Color Variability of Quasars Viewed with /GALEX
Zhu, Fei-Fan; Wang, Jun-Xian; Cai, Zhen-Yi; Sun, Yu-Han
2016-11-01
In a recent work by Sun et al., the color variation of quasars, namely the bluer-when-brighter trend, was found to be timescale dependent using the SDSS g/r band light curves in Stripe 82. Such timescale dependence, i.e., bluer variation at shorter timescales, supports the thermal fluctuation origin of the UV/optical variation in quasars, and can be modeled well with the inhomogeneous accretion disk model. In this paper, we extend the study to much shorter wavelengths in the rest frame (down to extreme UV) using GALaxy Evolution eXplorer (GALEX) photometric data of quasars collected in two ultraviolet bands (near-UV and far-UV). We develop Monte Carlo simulations to correct for possible biases due to the considerably larger photometric uncertainties in the GALEX light curves (particularly in the far-UV, compared with the SDSS g/r bands), which otherwise could produce artificial results. We securely confirm the previously discovered timescale dependence of the color variability with independent data sets and at shorter wavelengths. We further find that the slope of the correlation between the amplitude of the color variation and timescale appears even steeper than predicted by the inhomogeneous disk model, which assumes that disk fluctuations follow a damped random walk (DRW) process. The much flatter structure function observed in the far-UV compared with that at longer wavelengths implies deviation from the DRW process in the inner disk, where rest-frame extreme UV radiation is produced.
无
2010-01-01
To analyze the effect of basic variable on failure probability in reliability analysis,a moment-independent importance measure of the basic random variable is proposed,and its properties are analyzed and verified.Based on this work,the importance measure of the basic variable on the failure probability is compared with that on the distribution density of the response.By use of the probability density evolution method,a solution is established to solve two importance measures,which can efficiently avoid the difficulty in solving the importance measures.Some numerical examples and engineering examples are used to demonstrate the proposed importance measure on the failure probability and that on the distribution density of the response.The results show that the proposed importance measure can effectively describe the effect of the basic variable on the failure probability from the distribution density of the basic variable.Additionally,the results show that the established solution on the probability density evolution is efficient for the importance measures.
Solar cycles or random processes? Evaluating solar variability in Holocene climate records.
Turner, T Edward; Swindles, Graeme T; Charman, Dan J; Langdon, Peter G; Morris, Paul J; Booth, Robert K; Parry, Lauren E; Nichols, Jonathan E
2016-04-05
Many studies have reported evidence for solar-forcing of Holocene climate change across a range of archives. These studies have compared proxy-climate data with records of solar variability (e.g. (14)C or (10)Be), or have used time series analysis to test for the presence of solar-type cycles. This has led to some climate sceptics misrepresenting this literature to argue strongly that solar variability drove the rapid global temperature increase of the twentieth century. As proxy records underpin our understanding of the long-term processes governing climate, they need to be evaluated thoroughly. The peatland archive has become a prominent line of evidence for solar forcing of climate. Here we examine high-resolution peatland proxy climate data to determine whether solar signals are present. We find a wide range of significant periodicities similar to those in records of solar variability: periods between 40-100 years, and 120-140 years are particularly common. However, periodicities similar to those in the data are commonly found in random-walk simulations. Our results demonstrate that solar-type signals can be the product of random variations alone, and that a more critical approach is required for their robust interpretation.
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
Limitations on the recovery of the true AGN variability parameters using damped random walk modeling
Kozłowski, Szymon
2017-01-01
Context. The damped random walk (DRW) stochastic process is nowadays frequently used to model aperiodic light curves of active galactic nuclei (AGNs). A number of correlations between the DRW model parameters, the signal decorrelation timescale and amplitude, and the physical AGN parameters, such as the black hole mass or luminosity, have been reported. Aims: We are interested in whether or not it is plausible to correctly measure the DRW parameters from a typical ground-based survey, and, in particular, in how accurate the recovered DRW parameters are compared to the input ones. Methods: By means of Monte Carlo simulations of AGN light curves, we studied the impact of the light curve length, the source magnitude (the photometric properties of a survey), cadence, and additional light (e.g., from a host galaxy) on the DRW model parameters. Results: The most significant finding is that currently existing surveys are going to return unconstrained DRW decorrelation timescales, because typical rest-frame data do not probe long enough timescales or the white noise part of the power spectral density for DRW. The experiment length must be at least ten times longer than the true DRW decorrelation timescale, being presumably in the vicinity of one year, thus meaning the necessity for AGN light curves measuring a minimum of 10 years (rest-frame). The DRW timescales for sufficiently long light curves are typically weakly biased, and the exact bias depends on the fitting method and used priors. The DRW amplitude is mostly affected by the photometric noise (the source magnitude or the signal-to-noise ratio), cadence, and the AGN host light. Conclusions: Because the DRW parameters appear to be incorrectly determined from typically existing data, the reported correlations of the DRW variability and physical AGN parameters from other works seem unlikely to be correct. In particular, the anti-correlation of the DRW decorrelation timescale with redshift is a manifestation of the
Criticality in Two-Variable Earthquake Model on a Random Graph
SUN Fan; ZHANG Duan-Ming
2008-01-01
A two-variable earthquake model on a quenched random graph is established here. It can be seen as a generalization of the OFC models. We numerically study the critical behavior of the model when the system is nonconservative: the result indicates that the model exhibits self-organized criticality deep within the nonconservative regime. The probability distribution for avalanche size obeys finite size scaling. We compare our model with the model introduced by Stefano Lise and Maya Paczuski [Phys. Rev. Lett. 88 (2002) 228301], it is proved that they are not in the same universality class.
On Direction of Dependence in Latent Variable Contexts
von Eye, Alexander; Wiedermann, Wolfgang
2014-01-01
Approaches to determining direction of dependence in nonexperimental data are based on the relation between higher-than second-order moments on one side and correlation and regression models on the other. These approaches have experienced rapid development and are being applied in contexts such as research on partner violence, attention deficit…
Genuer, Robin; Toussile, Wilson
2011-01-01
Malaria control strategies aiming at reducing disease transmission intensity may impact both oocyst intensity and infection prevalence in the mosquito vector. Thus far, mathematical models failed to identify a clear relationship between Plasmodium falciparum gametocytes and their infectiousness to mosquitoes. Natural isolates of gametocytes are genetically diverse and biologically complex. Infectiousness to mosquitoes relies on multiple parameters such as density, sex-ratio, maturity, parasite genotypes and host immune factors. In this article, we investigated how density and genetic diversity of gametocytes impact on the success of transmission in the mosquito vector. We analyzed data for which the number of covariates plus attendant interactions is at least of order of the sample size, precluding usage of classical models such as general linear models. We then considered the variable importance from random forests to address the problem of selecting the most influent variables. The selected covariates were ...
van der Zwan, Judith Esi; de Vente, Wieke; Huizink, Anja C; Bögels, Susan M; de Bruin, Esther I
2015-12-01
In contemporary western societies stress is highly prevalent, therefore the need for stress-reducing methods is great. This randomized controlled trial compared the efficacy of self-help physical activity (PA), mindfulness meditation (MM), and heart rate variability biofeedback (HRV-BF) in reducing stress and its related symptoms. We randomly allocated 126 participants to PA, MM, or HRV-BF upon enrollment, of whom 76 agreed to participate. The interventions consisted of psycho-education and an introduction to the specific intervention techniques and 5 weeks of daily exercises at home. The PA exercises consisted of a vigorous-intensity activity of free choice. The MM exercises consisted of guided mindfulness meditation. The HRV-BF exercises consisted of slow breathing with a heart rate variability biofeedback device. Participants received daily reminders for their exercises and were contacted weekly to monitor their progress. They completed questionnaires prior to, directly after, and 6 weeks after the intervention. Results indicated an overall beneficial effect consisting of reduced stress, anxiety and depressive symptoms, and improved psychological well-being and sleep quality. No significant between-intervention effect was found, suggesting that PA, MM, and HRV-BF are equally effective in reducing stress and its related symptoms. These self-help interventions provide easily accessible help for people with stress complaints.
On the Distribution of Indefinite Quadratic Forms in Gaussian Random Variables
Al-Naffouri, Tareq Y.
2015-10-30
© 2015 IEEE. In this work, we propose a unified approach to evaluating the CDF and PDF of indefinite quadratic forms in Gaussian random variables. Such a quantity appears in many applications in communications, signal processing, information theory, and adaptive filtering. For example, this quantity appears in the mean-square-error (MSE) analysis of the normalized least-meansquare (NLMS) adaptive algorithm, and SINR associated with each beam in beam forming applications. The trick of the proposed approach is to replace inequalities that appear in the CDF calculation with unit step functions and to use complex integral representation of the the unit step function. Complex integration allows us then to evaluate the CDF in closed form for the zero mean case and as a single dimensional integral for the non-zero mean case. Utilizing the saddle point technique allows us to closely approximate such integrals in non zero mean case. We demonstrate how our approach can be extended to other scenarios such as the joint distribution of quadratic forms and ratios of such forms, and to characterize quadratic forms in isotropic distributed random variables.We also evaluate the outage probability in multiuser beamforming using our approach to provide an application of indefinite forms in communications.
A THEOREM ON THE CONVERGENCE OF SUMS OF INDEPENDENT RANDOM VARIABLES
无
2001-01-01
Let ∑∞n=1 Xn be a series of independent random variables with at least one non-degenerate Xn, and let Fn be the distribution function of its partial sums Sn =n∑k=1 Xk. Motivated by Hildebrand's work in [1], the authors investigate the a.s. convergence of ∞∑n=1 Xn under a hypothesis that ∞∑n=1 p(Xn,cn) = ∞ whenever ∞∑n=1 cn diverges, where the notation p(X,c) denotes the Lévy distance between the random variable X and the constant c. The principal result of this paper shows that the hypothesis is the condition under which the convergence of Fn(x0) with the limit value 0 ＜ L0 ＜ 1, together with the essential convergence of ∞∑n=1 Xn, is both sufficient and necessary in order for the series ∞∑n=1 Xn to a.s. converge. Moreover, if the essential convergence of ∞∑n=1 Xn is strengthened to limsup P(|Sn| ＜ K) = 1 for some K ＞ 0, the hypothesis is already equivalent to the a.s.convergence of ∞∑n=1 Xn. Here they have not only founded a very general limit theorem, but improved the related result in Hildebrand[1] as well.
Multiobjective Two-Stage Stochastic Programming Problems with Interval Discrete Random Variables
S. K. Barik
2012-01-01
Full Text Available Most of the real-life decision-making problems have more than one conflicting and incommensurable objective functions. In this paper, we present a multiobjective two-stage stochastic linear programming problem considering some parameters of the linear constraints as interval type discrete random variables with known probability distribution. Randomness of the discrete intervals are considered for the model parameters. Further, the concepts of best optimum and worst optimum solution are analyzed in two-stage stochastic programming. To solve the stated problem, first we remove the randomness of the problem and formulate an equivalent deterministic linear programming model with multiobjective interval coefficients. Then the deterministic multiobjective model is solved using weighting method, where we apply the solution procedure of interval linear programming technique. We obtain the upper and lower bound of the objective function as the best and the worst value, respectively. It highlights the possible risk involved in the decision-making tool. A numerical example is presented to demonstrate the proposed solution procedure.
On the Information of the Second Moments Between Random Variables Using Mutually Unbiased Bases
Yao, Hongyi
2007-01-01
The notation of mutually unbiased bases(MUB) was first introduced by Ivanovic to reconstruct density matrixes\\cite{Ivanovic}. The subject about how to use MUB to analyze, process, and utilize the information of the second moments between random variables is studied in this paper. In the first part, the mathematical foundation will be built. It will be shown that the spectra of MUB have complete information for the correlation matrixes of finite discrete signals, and the nice properties of them. Roughly speaking, it will be shown that each spectrum from MUB plays an equal role for finite discrete signals, and the effect between any two spectra can be treated as a global constant shift. These properties will be used to find some important and natural characterizations of random vectors and random discrete operators/filters. For a technical reason, it will be shown that any MUB spectra can be found as fast as Fourier spectrum when the length of the signal is a prime number. In the second part, some applications ...
Yan Xia REN
2008-01-01
The global supports of super-Poisson processes and super-random walks with a branching mechanism ψ(z)=z2 and constant branching rate are known to be noncompact. It turns out that, for any spatially dependent branching rate, this property remains true. However, the asymptotic extinction property for these two kinds of superprocesses depends on the decay rate of the branching-rate function at infinity.
JIANG Tao
2008-01-01
We establish an asymptotic relation for the large-deviation probabilities of the maxima of sums of subexponential random variables centered by multiples of order statistics of i.i.d. standard uniform random variables. This extends a corresponding result of Korshunov. As an application, we generalize a result of Tang,the uniform asymptotic estimate for the finite-time ruin probability, to the whole strongly subexponential class.
2008-01-01
We establish an asymptotic relation for the large-deviation probabilities of the maxima of sums of subexponential random variables centered by multiples of order statistics of i.i.d.standard uniform random variables.This extends a corresponding result of Korshunov.As an application,we generalize a result of Tang,the uniform asymptotic estimate for the finite-time ruin probability,to the whole strongly subexponential class.
Return Probability of the Open Quantum Random Walk with Time-Dependence
Clement Ampadu
2013-01-01
We study the open quantum random walk (OQRW) with time-dependence on the one-dimensional lattice space and obtain the associated limit distribution.As an application we study the return probability of the OQRW.We also ask,"What is the average time for the return probability of the OQRW?"
Energy decay of a variable-coefficient wave equation with nonlinear time-dependent localized damping
Jieqiong Wu
2015-09-01
Full Text Available We study the energy decay for the Cauchy problem of the wave equation with nonlinear time-dependent and space-dependent damping. The damping is localized in a bounded domain and near infinity, and the principal part of the wave equation has a variable-coefficient. We apply the multiplier method for variable-coefficient equations, and obtain an energy decay that depends on the property of the coefficient of the damping term.
Bershitskaya, O N; Izakov VYa; Lysenko, L T; Protsenko, J L; Trubetskoy, A V
1985-01-01
The relationship "heart rate - left ventricular pressure" was investigated in the isolated canine heart perfused with constant pressure at different preloads. Rhythmical stimulation was performed with constant stimulus interval duration and with stimulus intervals randomly changed near the average value (150-200 stimuli in series). Correlation and dispersion function analysis show that rhythm dispersion had a negative inotropic effect which was independent of the preload of the ventricle in the range of 120-180 beat/min, but this dependence occurred with low rats of stimulation. This method is proposed for the assessment of contractility under conditions of heart rate variations (physiological and pathological arrhythmias).
Franciele R Figueira
Full Text Available To evaluate the effects of aerobic (AER or aerobic plus resistance exercise (COMB sessions on glucose levels and glucose variability in patients with type 2 diabetes. Additionally, we assessed conventional and non-conventional methods to analyze glucose variability derived from multiple measurements performed with continuous glucose monitoring system (CGMS.Fourteen patients with type 2 diabetes (56±2 years wore a CGMS during 3 days. Participants randomly performed AER and COMB sessions, both in the morning (24 h after CGMS placement, and at least 7 days apart. Glucose variability was evaluated by glucose standard deviation, glucose variance, mean amplitude of glycemic excursions (MAGE, and glucose coefficient of variation (conventional methods as well as by spectral and symbolic analysis (non-conventional methods.Baseline fasting glycemia was 139±05 mg/dL and HbA1c 7.9±0.7%. Glucose levels decreased immediately after AER and COMB protocols by ∼16%, which was sustained for approximately 3 hours. Comparing the two exercise modalities, responses over a 24-h period after the sessions were similar for glucose levels, glucose variance and glucose coefficient of variation. In the symbolic analysis, increases in 0 V pattern (COMB, 67.0±7.1 vs. 76.0±6.3, P = 0.003 and decreases in 1 V pattern (COMB, 29.1±5.3 vs. 21.5±5.1, P = 0.004 were observed only after the COMB session.Both AER and COMB exercise modalities reduce glucose levels similarly for a short period of time. The use of non-conventional analysis indicates reduction of glucose variability after a single session of combined exercises.Aerobic training, aerobic-resistance training and glucose profile (CGMS in type 2 diabetes (CGMS exercise. ClinicalTrials.gov ID: NCT00887094.
Bias phase and light power dependence of the random walk coefficient of fiber optic gyroscope
Jian Mi; Chunxi Zhang; Zheng Li; Zhanjun Wu
2006-01-01
@@ Taking account of shot noise, thermal noise, dark current noise, and intensity noise that come from broad band light source, the dependence of the random walk coefficient of fiber optic gyroscope (FOG) on bias phase and light power is studied theoretically and experimentally. It is shown that with different optical and electronic parameters, the optimal bias phase is different and should be adjusted accordingly to improve the FOG precision. By choosing appropriate bias phase, the random walk coefficient of the aim FOG is reduced from 0.0026 to 0.0019 deg./h1/2.
Technique for computing the PDFs and CDFs of non-negative infinitely divisible random variables
Veillette, Mark S
2010-01-01
We present a method for computing the PDF and CDF of a non-negative infinitely divisible random variable $X$. Our method uses the L\\'{e}vy-Khintchine representation of the Laplace transform $\\mathbb{E} e^{-\\lambda X} = e^{-\\phi(\\lambda)}$, where $\\phi$ is the Laplace exponent. We apply the Post-Widder method for Laplace transform inversion combined with a sequence convergence accelerator to obtain accurate results. We demonstrate this technique on several examples including the stable distribution, mixtures thereof, and integrals with respect to non-negative L\\'{e}vy processes. Software to implement this method is available from the authors and we illustrate its use at the end of the paper.
A Random Variable Substitution Lemma With Applications to Multiple Description Coding
Wang, Jia; Zhao, Lei; Cuff, Paul; Permuter, Haim
2009-01-01
We establish a random variable substitution lemma and use it to investigate the role of refinement layer in multiple description coding, which clarifies the relationship among several existing achievable multiple description rate-distortion regions. Specifically, it is shown that the El Gamal-Cover (EGC) region is equivalent to the EGC* region (an antecedent version of the EGC region) while the Venkataramani-Kramer-Goyal (VKG) region (when specialized to the 2-description case) is equivalent to the Zhang-Berger (ZB) region. Moreover, we prove that for multiple description coding with individual and hierarchical distortion constraints, the number of layers in the VKG scheme can be significantly reduced when only certain weighted sum rates are concerned. The role of refinement layer in scalable coding (a special case of multiple description coding) is also studied.
Gui, Ming; Huang, Ming-Qiu; Liang, Lin-Mei
2016-10-01
In practical continuous-variable quantum key distribution (CVQKD) systems, due to environmental disturbance or some intrinsic imperfections of devices, inevitably the local oscillator (LO) employed in a coherent detection always fluctuates arbitrarily over time, which compromises the security and performance of practical CVQKD systems. In this paper, we investigate the performance of practical CVQKD systems with LO fluctuating randomly. By revising the measurement result of balanced homodyne detection and embedding fluctuation parameters into security analysis, we find that in addition to the average LO intensity, the fluctuation variance also severely affects the secret key rate. No secret key can be obtained if fluctuation variance is relatively large. This indicates that in a practical CVQKD, LO intensity should be well monitored and stabilized. Our research can be directly applied to improve the robustness of a practical CVQKD system as well as be used to optimize CVQKD protocols.
Deli Li
1992-01-01
Full Text Available Let X, Xn, n≥1 be a sequence of iid real random variables, and Sn=∑k=1nXk, n≥1. Convergence rates of moderate deviations are derived, i.e., the rate of convergence to zero of certain tail probabilities of the partial sums are determined. For example, we obtain equivalent conditions for the convergence of series ∑n≥1(ψ2(n/nP(|Sn|≥nφ(n only under the assumptions convergence that EX=0 and EX2=1, where φ and ψ are taken from a broad class of functions. These results generalize and improve some recent results of Li (1991 and Gafurov (1982 and some previous work of Davis (1968. For b∈[0,1] and ϵ>0, letλϵ,b=∑n≥3((loglognb/nI(|Sn|≥(2+ϵnloglogn.The behaviour of Eλϵ,b as ϵ↓0 is also studied.
黄兆霞
2014-01-01
The De finetti's theorem states that infinite exchangeable random variables sequences are independent and identically distribut-ed with the condition of the tailσ-algebra. So some results about independent identically distributed random variables are similar to ex-changeable random variables. This paper gives some conclusions of the relationship between exchangeable random variables and indepen-dent and identically distributed random variables.%由于可交换随机变量的基本结构定理De Finetti定理---可交换随机变量无限序列以其尾σ-代数为条件是独立同分布的，因而可交换随机变量应具有类似于独立同分布随机变量的性质。本文给出了可交换随机变量与独立同分布随机变量间关系的一些结论。
de Oliveira, Andréia M R; Matsumura, Aida T S; Prestes, Ariano M; Van Der Sand, Sueli T
2002-01-01
Isolates of Bipolaris sorokiniana were analyzed by random-amplified polymorphic DNA (RAPD) techniques to determine the amount of intraspecific genetic variability and to study host-pathogen interactions. Ten isolates originated from different regions of Brazil were examined. Plants of the wheat cultivars BR8, BH1146 (original host) and IAC-5 Maringá, classified as resistant, moderately resistant or susceptible to B. sorokiniana, respectively, were inoculated with these 10 isolates. Twenty-seven isolates were recovered from these cultivars and were analyzed by RAPD assay and compared to the RAPD of the original 10 isolates. According to the RAPD profiles there was a high level of genetic variability among the isolates. We detected 69 polymorphic fragments, ranging from 1.6 to 0.54 kb, in the original 10 isolates; 57 fragments with sizes between 1.98 and 0.38 kb from the isolates recovered from BH1146; 47 polymorphic bands, ranging from 1.96-0.54 kb, were detected in the isolates from BR8 and 32 fragments between 1.98 and 0.42 kb in isolates were recovered from IAC-5 Maringá. The number of polymorphic fragments varied, even for the same isolate, when the isolates were recovered from different cultivar hosts.
Are the Variability Properties of the Kepler AGN Light Curves Consistent with a Damped Random Walk?
Kasliwal, Vishal P; Richards, Gordon T
2015-01-01
We test the consistency of active galactic nuclei (AGN) optical flux variability with the \\textit{damped random walk} (DRW) model. Our sample consists of 20 multi-quarter \\textit{Kepler} AGN light curves including both Type 1 and 2 Seyferts, radio-loud and -quiet AGN, quasars, and blazars. \\textit{Kepler} observations of AGN light curves offer a unique insight into the variability properties of AGN light curves because of the very rapid ($11.6-28.6$ min) and highly uniform rest-frame sampling combined with a photometric precision of $1$ part in $10^{5}$ over a period of 3.5 yr. We categorize the light curves of all 20 objects based on visual similarities and find that the light curves fall into 5 broad categories. We measure the first order structure function of these light curves and model the observed light curve with a general broken power-law PSD characterized by a short-timescale power-law index $\\gamma$ and turnover timescale $\\tau$. We find that less than half the objects are consistent with a DRW and ...
无
2002-01-01
Objective To design and develop a novel, sensitive and versatile method for in vivo foot printing and studies of DNA damage, such as DNA adducts and strand breaks. Methods Starting with mammalian genomic DNA, single-stranded products were made by repeated primer extension, these products were ligated to a double-stranded linker having a randomized 3′ overhang, and used for PCR.DNA breaks in p53 gene produced by restriction endonuclease AfaI were detected by using this new method followed by Southern hybridization with DIG-labeled probe. Results This randomized terminal linker-dependent PCR (RDPCR) method could generate band signals many-fold stronger than conventional ligation-mediated PCR (LMPCR), and it was more rapid, convenient and accurate than the terminal transferase-dependent PCR (TDPCR). Conclusion DNA strand breakage can be detected sensitively in the gene level by RDPCR. Any lesion that blocks primer extension should be detectable.
Synaptic Variability Introduces State-Dependent Modulation of Excitatory Spinal Cord Synapses
David Parker
2015-01-01
Full Text Available The relevance of neuronal and synaptic variability remains unclear. Cellular and synaptic plasticity and neuromodulation are also variable. This could reflect state-dependent effects caused by the variable initial cellular or synaptic properties or direct variability in plasticity-inducing mechanisms. This study has examined state-dependent influences on synaptic plasticity at connections between excitatory interneurons (EIN and motor neurons in the lamprey spinal cord. State-dependent effects were examined by correlating initial synaptic properties with the substance P-mediated plasticity of low frequency-evoked EPSPs and the reduction of the EPSP depression over spike trains (metaplasticity. The low frequency EPSP potentiation reflected an interaction between the potentiation of NMDA responses and the release probability. The release probability introduced a variable state-dependent subtractive influence on the postsynaptic NMDA-dependent potentiation. The metaplasticity was also state-dependent: it was greater at connections with smaller available vesicle pools and high initial release probabilities. This was supported by the significant reduction in the number of connections showing metaplasticity when the release probability was reduced by high Mg2+ Ringer. Initial synaptic properties thus introduce state-dependent influences that affect the potential for plasticity. Understanding these conditions will be as important as understanding the subsequent changes.
Synaptic Variability Introduces State-Dependent Modulation of Excitatory Spinal Cord Synapses.
Parker, David
2015-01-01
The relevance of neuronal and synaptic variability remains unclear. Cellular and synaptic plasticity and neuromodulation are also variable. This could reflect state-dependent effects caused by the variable initial cellular or synaptic properties or direct variability in plasticity-inducing mechanisms. This study has examined state-dependent influences on synaptic plasticity at connections between excitatory interneurons (EIN) and motor neurons in the lamprey spinal cord. State-dependent effects were examined by correlating initial synaptic properties with the substance P-mediated plasticity of low frequency-evoked EPSPs and the reduction of the EPSP depression over spike trains (metaplasticity). The low frequency EPSP potentiation reflected an interaction between the potentiation of NMDA responses and the release probability. The release probability introduced a variable state-dependent subtractive influence on the postsynaptic NMDA-dependent potentiation. The metaplasticity was also state-dependent: it was greater at connections with smaller available vesicle pools and high initial release probabilities. This was supported by the significant reduction in the number of connections showing metaplasticity when the release probability was reduced by high Mg(2+) Ringer. Initial synaptic properties thus introduce state-dependent influences that affect the potential for plasticity. Understanding these conditions will be as important as understanding the subsequent changes.
McClintock, Andrew S; Anderson, Timothy; Cranston, Saryn
2015-11-01
Existing treatments for maladaptive interpersonal dependency and dependent personality disorder do not meet basic scientific standards for effectiveness. The present investigation tested the efficacy of a mindfulness-based approach: mindfulness therapy for maladaptive interpersonal dependency (MT-MID). Forty-eight participants who reported consistently high levels of maladaptive dependency (i.e., scored higher than 1 standard deviation above the mean on the Interpersonal Dependency Inventory at two separate assessments) were randomized to either 5 sessions of MT-MID or a minimal contact control. Five self-reported outcomes (mindfulness, maladaptive interpersonal dependency, helplessness, fears of negative evaluation, and excessive reassurance seeking) were assessed at pretreatment, posttreatment, and a 4-week follow-up. Intent-to-treat analyses indicated that MT-MID yielded greater improvements than the control on all 5 outcomes at posttreatment (median d=1.61) and follow-up (median d=1.51). Participants assigned to MT-MID were more likely than control participants to meet criteria for clinically significant change at posttreatment (56.5% vs. 0%) and follow-up (42.9% vs. 0%). There was also evidence that increases in mindfulness mediated the dependency-related improvements. These results provide preliminary support for the efficacy of a mindfulness-based approach for treating the symptoms of maladaptive dependency.
LIU Hai; LIU JinSong; L(U) JianTao; WANG KeJia
2009-01-01
Polarization-dependent difference of the power spectra from a set of two-dimensional (2D) passive random media is investigated by simultaneously solving Maxwell's equations for both transverse magnetic (TM) and transverse electric (TE) fields. The random media have the same random constitution but different shapes. Results show that both two polarized states are morphology dependent,and the variety of the shapes has more influence on the selection of TM polarized modes than that of TE polarized modes. Such polarization-dependent difference of morphology property presents a new modeselecting technique for random lasers.
Anomalous transport in fluid field with random waiting time depending on the preceding jump length
Zhang, Hong; Li, Guo-Hua
2016-11-01
Anomalous (or non-Fickian) transport behaviors of particles have been widely observed in complex porous media. To capture the energy-dependent characteristics of non-Fickian transport of a particle in flow fields, in the present paper a generalized continuous time random walk model whose waiting time probability distribution depends on the preceding jump length is introduced, and the corresponding master equation in Fourier-Laplace space for the distribution of particles is derived. As examples, two generalized advection-dispersion equations for Gaussian distribution and lévy flight with the probability density function of waiting time being quadratic dependent on the preceding jump length are obtained by applying the derived master equation. Project supported by the Foundation for Young Key Teachers of Chengdu University of Technology, China (Grant No. KYGG201414) and the Opening Foundation of Geomathematics Key Laboratory of Sichuan Province, China (Grant No. scsxdz2013009).
Surface effects of electrode-dependent switching behavior of resistive random-access memory
Ke, Jr Jian
2016-09-26
The surface effects of ZnO-based resistive random-access memory (ReRAM) were investigated using various electrodes. Pt electrodes were found to have better performance in terms of the device\\'s switching functionality. A thermodynamic model of the oxygen chemisorption process was proposed to explain this electrode-dependent switching behavior. The temperature-dependent switching voltage demonstrates that the ReRAM devices fabricated with Pt electrodes have a lower activation energy for the chemisorption process, resulting in a better resistive switching performance. These findings provide an in-depth understanding of electrode-dependent switching behaviors and can serve as design guidelines for future ReRAM devices.
Shuwei Zhang
2011-02-01
Full Text Available Experimental pEC50s for 216 selective respiratory syncytial virus (RSV inhibitors are used to develop classification models as a potential screening tool for a large library of target compounds. Variable selection algorithm coupled with random forests (VS-RF is used to extract the physicochemical features most relevant to the RSV inhibition. Based on the selected small set of descriptors, four other widely used approaches, i.e., support vector machine (SVM, Gaussian process (GP, linear discriminant analysis (LDA and k nearest neighbors (kNN routines are also employed and compared with the VS-RF method in terms of several of rigorous evaluation criteria. The obtained results indicate that the VS-RF model is a powerful tool for classification of RSV inhibitors, producing the highest overall accuracy of 94.34% for the external prediction set, which significantly outperforms the other four methods with the average accuracy of 80.66%. The proposed model with excellent prediction capacity from internal to external quality should be important for screening and optimization of potential RSV inhibitors prior to chemical synthesis in drug development.
Variability of Fiber Elastic Moduli in Composite Random Fiber Networks Makes the Network Softer
Ban, Ehsan; Picu, Catalin
2015-03-01
Athermal fiber networks are assemblies of beams or trusses. They have been used to model mechanics of fibrous materials such as biopolymer gels and synthetic nonwovens. Elasticity of these networks has been studied in terms of various microstructural parameters such as the stiffness of their constituent fibers. In this work we investigate the elasticity of composite fiber networks made from fibers with moduli sampled from a distribution function. We use finite elements simulations to study networks made by 3D Voronoi and Delaunay tessellations. The resulting data collapse to power laws showing that variability in fiber stiffness makes fiber networks softer. We also support the findings by analytical arguments. Finally, we apply these results to a network with curved fibers to explain the dependence of the network's modulus on the variation of its structural parameters.
Synchronized Flow in a Cellular Automaton Model with Time Headway Dependent Randomization
CHEN Tao; JIA Bin; LI Xin-Gang; JIANG Rui; GAO Zi-You
2008-01-01
@@ We propose another possible mechanism of synchronized flow, I.e. That a time headway dependent randomization can exhibit synchronized flow. Based on this assumption, we present a new cellular automaton (CA) model for traffic flow, in which randomization effect is enhanced with the decrease of time headway. We study fundamental diagram and spatial-temporal diagrams of the model and perform microscopic analysis of time series data, which shows the model could reproduce synchronized flow as expected. It is also shown that a spontaneous transition from synchronized flow to jam could be observed by incorporating slow-to-start effect into the model. We expect that our work could contribute to the understanding of the real origin of synchronized flow.
Mokaedi V. Lekgari
2014-01-01
Full Text Available We investigate random-time state-dependent Foster-Lyapunov analysis on subgeometric rate ergodicity of continuous-time Markov chains (CTMCs. We are mainly concerned with making use of the available results on deterministic state-dependent drift conditions for CTMCs and on random-time state-dependent drift conditions for discrete-time Markov chains and transferring them to CTMCs.
吴永锋
2015-01-01
本文研究了两两NQD随机变量的Marcinkiewicz-Zygmund不等式及其应用的问题。利用截尾的方法，获得了两两NQD随机变量的p阶(1≤p<2)Marcinkiewicz-Zygmund不等式结果。作为应用，获得了两两NQD随机变量的两个Lr收敛性结果的简单证明，改进了陈平炎[10]和Sung [20]的相应工作。%In this paper, the author studies the Marcinkiewicz-Zygmund inequality for pair-wise negative quadrant dependent (NQD) random variables and it applications. By using the truncated method, the author obtains the Marcinkiewicz-Zygmund inequality with exponent p (1≤p<2) for pairwise NQD random variables. As applications, the author obtains the simpler proofs of two Lr convergence results for pairwise NQD random variables, which improve the corre-sponding work by Chen [10] and Sung [20] respectively.
Walitzer, Kimberly S; Deffenbacher, Jerry L; Shyhalla, Kathleen
2015-12-01
A randomized controlled trial for an innovative alcohol-adapted anger management treatment (AM) for outpatient alcohol dependent individuals scoring moderate or above on anger is described. AM treatment outcomes were compared to those of an empirically-supported intervention, Alcoholics Anonymous Facilitation treatment (AAF). Clients in AM, relative to clients in AAF, were hypothesized to have greater improvement in anger and anger-related cognitions and lesser AA involvement during the 6-month follow-up. Anger-related variables were hypothesized to be stronger predictors of improved alcohol outcomes in the AM treatment condition and AA involvement was hypothesized to be a stronger predictor of alcohol outcomes in the AAF treatment group. Seventy-six alcohol dependent men and women were randomly assigned to treatment condition and followed for 6 months after treatment end. Both AM and AAF treatments were followed by significant reductions in heavy drinking days, alcohol consequences, anger, and maladaptive anger-related thoughts and increases in abstinence and self-confidence regarding not drinking to anger-related triggers. Treatment with AAF was associated with greater AA involvement relative to treatment with AM. Changes in anger and AA involvement were predictive of posttreatment alcohol outcomes for both treatments. Change in trait anger was a stronger predictor of posttreatment alcohol consequences for AM than for AAF clients; during-treatment AA meeting attendance was a stronger predictor of posttreatment heavy drinking and alcohol consequences for AAF than for AM clients. Anger-related constructs and drinking triggers should be foci in treatment of alcohol dependence for anger-involved clients.
Gilburt, Helen; Burns, Tom; Copello, Alex; Crawford, Michael; Day, Ed; Deluca, Paolo; Godfrey, Christine; Parrott, Steve; Rose, Abigail; Sinclair, Julia; Coulton, Simon
2017-01-01
Abstract Aims A pilot randomized controlled trial (RCT) to assess the feasibility and potential efficacy of assertive community treatment (ACT) in adults with alcohol dependence. Methods Single blind, individually randomized, pilot RCT of 12 months of ACT plus treatment as usual (TAU) versus TAU alone in adults (age 18+ years) with alcohol dependence and a history of previous unsuccessful alcohol treatment attending specialist community alcohol treatment services. ACT aimed to actively engage participants for 12 months with assertive, regular, minimum weekly contact. ACT was combined with TAU. TAU comprised access to the full range of services provided by the community teams. Primary outcome is mean drinks per drinking day and percent days abstinent at 12 months follow up. Analysis of covariance was conducted using 80% confidence intervals, appropriate in the context of a pilot trial. Results A total of 94 participants were randomized, 45 in ACT and 49 in TAU. Follow-up was achieved with 98 and 88%, respectively at 12 months. Those in ACT had better treatment engagement, and were more often seen in their homes or local community than TAU participants. At 12 months the ACT group had more problems related to drinking and lower quality of life than TAU but no differences in drinking measures. The ACT group had a higher percentage of days abstinent but lower quality of life at 6 months. The ACT group had less unplanned healthcare use than TAU. Conclusions An trial of ACT was feasible to implement in an alcohol dependent treatment population. Trial registration ISRCTN22775534 PMID:27940571
Random walk in degree space and the time-dependent Watts-Strogatz model
Grande, H L Casa; Hase, M O
2016-01-01
In this work, we propose a scheme that provides an analytical estimate for the time-dependent degree distribution of some networks. This scheme maps the problem into a random walk in degree space, and then we choose the paths that are responsible for the dominant contributions. The method is illustrated on the dynamical versions of the Erd\\"os-R\\'enyi and Watts-Strogatz graphs, which were introduced as static models in the original formulation. We have succeeded in obtaining an analytical form for the dynamics Watts-Strogatz model, which is asymptotically exact for some regimes.
LIN Zhengyan
2004-01-01
We introduce a new class of dependent sequences of random variables, which is a subclass of near-epoch dependent sequences, but can also be approximated by mixing sequences. For this kind of sequences of random variables, we call them strong nearepoch dependent sequences, a p-order, p ＞ 2, (maximum) moment inequality is established under weaker dependence sizes.
On the dependence of QCD splitting functions on the choice of the evolution variable
Jadach, S; Placzek, W; Skrzypek, M
2016-01-01
We show that already at the NLO level the DGLAP evolution kernel Pqq starts to depend on the choice of the evolution variable. We give an explicit example of such a variable, namely the maximum of transverse momenta of emitted partons and we identify a class of evolution variables that leave the NLO Pqq kernel unchanged with respect to the known standard MS-bar results. The kernels are calculated using a modified Curci-Furmanski-Petronzio method which is based on a direct Feynman-graphs calculation.
On the dependence of QCD splitting functions on the choice of the evolution variable
Jadach, S.; Kusina, A.; Placzek, W.; Skrzypek, M.
2016-08-01
We show that already at the NLO level the DGLAP evolution kernel P qq starts to depend on the choice of the evolution variable. We give an explicit example of such a variable, namely the maximum of transverse momenta of emitted partons and we identify a class of evolution variables that leave the NLO P qq kernel unchanged with respect to the known standard overline{MS} results. The kernels are calculated using a modified Curci-Furmanski-Petronzio method which is based on a direct Feynman-graphs calculation.
Baugher, Benjamin
2008-01-01
We prove the main conjecture from [M. R. Douglas, B. Shiffman and S. Zelditch, Critical points and supersymmetric vacua, II: Asymptotics and extremal metrics. J. Differential Geom. 72 (2006), no. 3, 381-427] concerning the metric dependence and asymptotic minimization of the expected number \\mathcal{N}^{crit}_{N,h} of critical points of random holomorphic sections of the Nth tensor power of a positive line bundle. The first non-topological term in the asymptotic expansion of \\mathcal{N}^{crit}_{N,h} is the the Calabi functional multiplied by the constant \\be_2(m) which depends only on the dimension of the manifold. We prove that \\be_2(m) is strictly positive in all dimensions, showing that the expansion is non-topological for all m, and that the Calabi extremal metric, when it exists, asymptotically minimizes \\mathcal{N}^{crit}_{N,h}.
DIYAH MARTANTI
2008-10-01
Full Text Available Amorphophallus muelleri Blume (Araceae is valued for its glucomanan content for use in food industry (healthy diet food, paper industry, pharmacy and cosmetics. The species is triploid (2n=3x=39 and the seed is developed apomictically. The present research is aimed to identify genetic variability of six population of A. muelleri from Java (consisted of 50 accessions using random amplified polymorphic DNA (RAPD. The six populations of the species are: East Java: (1 Silo-Jember, (2 Saradan-Madiun, (3 IPB (cultivated, from Saradan-Madiun, (4 Panti-Jember, (5 Probolinggo; and Central Java: (6 Cilacap. The results showed that five RAPD primers generated 42 scorable bands of which 29 (69.05% were polymorphic. Size of the bands varied from 300bp to 1.5kbp. The 50 accessions of A. muelleri were divided into two main clusters, some of them were grouped based on their populations, and some others were not. The range of individual genetic dissimilarity was from 0.02 to 0.36. The results showed that among six populations investigated, Saradan population showed the highest levels of genetic variation with mean values of na = 1.500+ 0.5061, ne = 1.3174 + 0.3841, PLP = 50% and He = 0, 0.1832+0.2054, whereas Silo-Jember population showed the lowest levels of genetic variation with mean values na = 1.2619+ 0.4450, ne = 1.1890 + 0.3507, PLP = 26.19% and He = 0.1048+0.1887. Efforts to conserve, domesticate, cultivate and improve genetically should be based on the genetic properties of each population and individual within population, especially Saradan population which has the highest levels of genetic variation, need more attention for its conservation.
Homogenization for rigid suspensions with random velocity-dependent interfacial forces
Gorb, Yuliya
2014-12-01
We study suspensions of solid particles in a viscous incompressible fluid in the presence of random velocity-dependent interfacial forces. The flow at a small Reynolds number is modeled by the Stokes equations, coupled with the motion of rigid particles arranged in a periodic array. The objective is to perform homogenization for the given suspension and obtain an equivalent description of a homogeneous (effective) medium, the macroscopic effect of the interfacial forces and the effective viscosity are determined using the analysis on a periodicity cell. In particular, the solutions uωε to a family of problems corresponding to the size of microstructure ε and describing suspensions of rigid particles with random surface forces imposed on the interface, converge H1-weakly as ε→0 a.s. to a solution of a Stokes homogenized problem, with velocity dependent body forces. A corrector to a homogenized solution that yields a strong H1-convergence is also determined. The main technical construction is built upon the Γ-convergence theory. © 2014 Elsevier Inc.
Effect of add-on valproate on craving in methamphetamine depended patients: A randomized trial
Kheirabadi, Gholam Reza; Ghavami, Masoud; Maracy, Mohammad Reza; Salehi, Mehrdad; Sharbafchi, Mohammad Reza
2016-01-01
Background: Methamphetamine dependence lead to the compulsive use, loss of control, and social and occupational dysfunctions. This study aimed to compare the effect of valproate in reducing the craving in methamphetamine dependents. Materials and Methods: This is a randomized, double-blind, controlled clinical trial on 40 men of 18–40 years old referred to Noor Hospital during December 2012–September 2013 in Isfahan, Iran. The subjects participated in matrix program and randomly were divided into two groups of valproate and placebo. A 4-months program of intervention with valproate or placebo was arranged for each group. The rate of craving to methamphetamine and positive methamphetamine urine tests were evaluated in both groups every 2 weeks using cocaine craving questionnaire-brief (CCQ-Brief) and urine test. After the 4 months (active treatment with valproate and placebo), the drug was tapered and discontinued within 10 days, and patients were introduced to self-help groups and monitored regularly on a weekly basis over another 3 months. Collected data were analyzed with SPSS 20 using analysis of covariance repeated measure, Chi-square, and t-test. Results: CCQ score of the intervention group was significantly less than the placebo group (P craving to methamphetamine. PMID:27656618
B. Li
2012-09-01
Full Text Available Past studies on soil moisture spatial variability have been mainly conducted in catchment scales where soil moisture is often sampled over a short time period. Because of limited climate and weather conditions, the observed soil moisture often exhibited smaller dynamic ranges which prevented the complete revelation of soil moisture spatial variability as a function of mean soil moisture. In this study, spatial statistics (mean, spatial variability and skewness of in situ soil moisture measurements (from a continuously monitored network across the US, modeled and satellite retrieved soil moisture obtained in a warm season (198 days were examined at large extent scales (>100 km over three different climate regions. The investigation on in situ measurements revealed that their spatial moments strongly depend on climates, with distinct mean, spatial variability and skewness observed in each climate zone. In addition, an upward convex shape, which was revealed in several smaller scale studies, was observed for the relationship between spatial variability of in situ soil moisture and its spatial mean across dry, intermediate, and wet climates. These climate specific features were vaguely or partially observable in modeled and satellite retrieved soil moisture estimates, which is attributed to the fact that these two data sets do not have climate specific and seasonal sensitive mean soil moisture values, in addition to lack of dynamic ranges. From the point measurements to satellite retrievals, soil moisture spatial variability decreased in each climate region. The three data sources all followed the power law in the scale dependency of spatial variability, with coarser resolution data showing stronger scale dependency than finer ones. The main findings from this study are: (1 the statistical distribution of soil moisture depends on spatial mean soil moisture values and thus need to be derived locally within any given area; (2 the boundedness of soil
Large Deviations for Sums of Heavy-tailed Random Variables%重尾随机变量和的大偏差
郭晓燕; 孔繁超
2007-01-01
This paper is a further investigation of large deviations for sums of random variables Sn =n∑i=1 Xi and S(t)=N(t)∑i=1 Xi,(t≥0), where {Xn,n≥1} are independent identically distribution and non-negative random variables, and {N(t),t≥0} is a counting process of non-negative integer-valued random variables, independent of {Xn,n≥1}. In this paper, under the suppose F ∈G, which is a bigger heavy-tailed class than C, proved large deviation results for sums of random variables.
下侧二重随机Dirichlet级数的相关收敛性%Dependent Convergence of Lower Side Bivalent Random Dirichlet Series
尤秀英
2001-01-01
在下侧二重Dirichlet级数的相关一致有界收敛定理及Knopp-Kojima公式的基础上，通过引入一个随机变量序列，在概率空间(Ω,A,P)上定义了下侧二重随机Dirichlet级数，建立了该级数的收敛性理论与Knopp-Kojima的推广公式。%On the basis of dependent bound convergence uniformly theorem andKnopp-Kojima formula of lower side bivalent Dirichlet series, this paper introduces one random variable sequence, and defines lower side bivalent random Dirichlet series on probability space (Ω,A,P). The converge theory and Knopp-Kojima extending formula of the lower side bivalent random Dirichlet series are established.
Nutrition education intervention for dependent patients: protocol of a randomized controlled trial
Arija Victoria
2012-05-01
Full Text Available Abstract Background Malnutrition in dependent patients has a high prevalence and can influence the prognosis associated with diverse pathologic processes, decrease quality of life, and increase morbidity-mortality and hospital admissions. The aim of the study is to assess the effect of an educational intervention for caregivers on the nutritional status of dependent patients at risk of malnutrition. Methods/Design Intervention study with control group, randomly allocated, of 200 patients of the Home Care Program carried out in 8 Primary Care Centers (Spain. These patients are dependent and at risk of malnutrition, older than 65, and have caregivers. The socioeconomic and educational characteristics of the patient and the caregiver are recorded. On a schedule of 0–6–12 months, patients are evaluated as follows: Mini Nutritional Assessment (MNA, food intake, dentures, degree of dependency (Barthel test, cognitive state (Pfeiffer test, mood status (Yesavage test, and anthropometric and serum parameters of nutritional status: albumin, prealbumin, transferrin, haemoglobin, lymphocyte count, iron, and ferritin. Prior to the intervention, the educational procedure and the design of educational material are standardized among nurses. The nurses conduct an initial session for caregivers and then monitor the education impact at home every month (4 visits up to 6 months. The North American Nursing Diagnosis Association (NANDA methodology will be used. The investigators will study the effect of the intervention with caregivers on the patient’s nutritional status using the MNA test, diet, anthropometry, and biochemical parameters. Bivariate normal test statistics and multivariate models will be created to adjust the effect of the intervention. The SPSS/PC program will be used for statistical analysis. Discussion The nutritional status of dependent patients has been little studied. This study allows us to know nutritional risk from different points of
A note on the Marchenko-Pastur law for a class of random matrices with dependent entries
O'Rourke, Sean
2012-01-01
We consider a class of real random matrices with dependent entries and show that the limiting empirical spectral distribution is given by the Marchenko-Pastur law. Additionally, we establish a rate of convergence of the expected empirical spectral distribution.
Dustmann, C.; van Soest, A.H.O.
1999-01-01
We consider both a parametric and a semiparametric method to account for classification errors on the dependent variable in an ordered response model. The methods are applied to the analysis of self-reported speaking fluency of male immigrants in Germany. We find some substantial differences in para
Field Dependency, n Power and Locus of Control Variables in Alcohol Aversion.
Query, William T.
1983-01-01
Compared individual differences and treatment effectiveness in male volunteer alcoholics (N=47) in a 10-day electroconditioning aversion program. Follow-up showed combination therapy was more successful. Internals and hard liquor drinkers tended to be abstinent as predicted. Field dependency was a more unstable variable for outcome. (Author/JAC)
Dupuis, J.; Biesbroek, G.R.
2013-01-01
An increasing number of studies have compared climate change adaptation policies within and between different countries. In this paper we show that these comparative studies suffer from what is known as the ‘‘dependent variable problem’ – the indistinctness of the phenomenon that is being measured,
Eijk, van der Cees; Brug, van der Wouter; Kroh, Martin; Franklin, Mark
2006-01-01
As a dependent variable, party choice did not lend itself to analysis by means of powerful multivariate methods until the coming of discrete-choice models, most notably conditional logit and multinomial logit. These methods involve estimating effects on party preferences (utilities) that are post ho
DeVito, Elise E.; Babuscio, Theresa A.; Nich, Charla; Ball, Samuel A.; Carroll, Kathleen M.
2014-01-01
Background Despite extensive research on gender differences in addiction, there are relatively few published reports comparing treatment outcomes for women versus men based on evidence-based treatments evaluated in randomized clinical trials. Methods An aggregate sample comprised of data from five randomized clinical trials of treatment for cocaine dependence (N = 434) was evaluated for gender differences in clinical outcomes. Secondary analyses compared gender differences in outcome by medication condition (disulfiram versus no medication) and across multiple behavioral treatment conditions. Results Women, compared with men, had poorer treatment outcomes on multiple measures of cocaine use during treatment and at post-treatment follow-up. These results appear to be primarily accounted for by disulfiram being less effective in women compared with men. There was no evidence of meaningful gender differences in outcome as a function of the behavioral therapies evaluated. Conclusions These findings suggest that women and men may benefit to similar degrees from some empirically validated behavioral treatments for addiction. Conversely, some addiction pharmacotherapies, such as disulfiram, may be associated with poorer outcomes among women relative to men and point to the need for careful assessment of pharmacological treatments in both sexes prior to widespread clinical implementation. PMID:25457739
Time-dependent Relativistic Mean-field Theory and Random Phase Approximation
P.Ring; D.Vretenar; A.Wandelt; NguyenVanGiai; MAZhong-yu; CAOLi-gang
2001-01-01
The relativistic random phase approximation (RRPA) is derived from the time-dependent relativistic mean field (TD RMF) theory in the limit of small amplitude oscillations. In the no-sea approximation of the RMF theory, the RRPA configuration space includes not only the usual particle-hole ph-states, but also ah configurations, i.e. pairs formed from occupied states in the Fermi sea and empty negative-energy states in the Dirac sea. The contribution of the negative energy states to the RRPA matrices is examined in a schematic model, and the large effect of Dirac sea states on isoscalar strength distributions is illustrated for the giant monopole resonance in 116Sn. It is shown that
Raj K Manchanda
2016-01-01
Full Text Available Objectives: This study was undertaken to compare the effects of IH with standard allopathic (SA treatment. Methods: A randomized controlled, open-label, comparative trial, was conducted, in which alcohol dependents were screened verbally using the CAGE scale. The participants 80 patients fulfilling the inclusion criteria were randomized either IH (n=40 or SA (n=40 and treated cum followed up for 12 months. The primary outcome was more than 50% reduction in the Severity of Alcohol Dependence Questionnaire [SADQ] rating scale at 12 th month. Data analysis was done for both intention-to-treat (ITT and per-protocol (PP populations. Results: ITT analysis reflected 80% (n = 32 of the patients in IH and 37.5% (n = 15 of the patients in the SA responding to CI before 2.4 treatment with absolute difference was 42.5% (42.5 [95% confidence interval [CI]: 23.0, 61.6] and estimated effect: 6.6 (95% C.I: 2.4, 18.2, P = 0.0002. A significant difference favoring IH was also observed in three out of four domains of WHO QOL-BREF. Statistically significant difference was found in the number of drinking days (median difference: −24.00; CI: −39.0-−8.0; P = 0.001 and number of drinks per drinking day (median difference: −6.3 [95% CI: −11.3-−1.9]; P = 0.004, favoring IH. The results showed a similar trend in PP analysis. Medicines found useful were Sulphur, Lycopodium clavatum, Arsenicum album, Nux vomica, Phosphorus, and Lachesis. Conclusion: The results conclude that IH is not inferior to SA in the management of AD patients. More rigorous studies with large sample size are however desirable.
Estimate Theorems About Sums of Random Variables%随机变量和的估计定理
张丽娜; 陈俊英; 闫广州
2011-01-01
建立了关于随机序列部分和及加权和增长阶的估计,推广了Freedman收敛速度和已有的结果,这些结果除矩条件外,对随机变量的独立性和联合分布不作具体要求.最后揭示了序偶序列出现的频数与转移概率之间的关系.%The estimate theorems of partial sums and weighted sums for stochastic sequence are established using the known results. These theorems and corollaries have extended the growth rates established by Freed-man. No condition of independence or the distribution of random variables are required except the conditions on moments of random variables. Finally,the relationship between frequency and transition probability is obtained.
Bounds and approximations for sums of dependent log-elliptical random variables
Valdez, E.A.; Dhaene, J.; Maj, M.; Vanduffel, S.
2009-01-01
Dhaene, Denuit, Goovaerts, Kaas and Vyncke [Dhaene, J., Denuit, M., Goovaerts, M.J., Kaas, R., Vyncke, D., 2002a. The concept of comonotonicity in actuarial science and finance: theory. Insurance Math. Econom. 31 (1), 3-33; Dhaene, J., Denuit, M., Goovaerts, M.J., Kaas, R., Vyncke, D., 2002b. The co
On a Camassa-Holm type equation with two dependent variables
Falqui, Gregorio [SISSA, Via Beirut 2/4, I-34014 Trieste (Italy)
2006-01-13
We consider a generalization of the Camassa-Holm (CH) equation with two dependent variables, called CH2, introduced in a paper by Liu and Zhang (Liu S-Q and Zhang Y 2005 J. Geom. Phys. 54 427-53). We briefly provide an alternative derivation of it based on the theory of Hamiltonian structures on (the dual of) a Lie algebra. The Lie algebra involved here is the same algebra as underlies the NLS hierarchy. We study the structural properties of the hierarchy defined by the CH2 equation within the bi-Hamiltonian theory of integrable PDEs, and provide its Lax representation. Then we explicitly discuss how to construct classes of solutions, both of peakon and of algebro-geometrical type. Finally we sketch the construction of a class of singular solutions, defined by setting to zero one of the two dependent variables.
Cerebral Hemodynamics With rTMS in Alcohol Dependence: A Randomized, Sham-Controlled Study.
Mishra, Biswa Ranjan; Maiti, Rituparna; Nizamie, S Haque
2016-04-08
The authors studied cerebral hemodynamics in alcohol dependence and evaluated their changes with application of high-frequency rTMS. A prospective, single-blind, randomized, parallel-group, sham-controlled clinical study was conducted with patients with alcohol dependence (DSM-IV-TR). The study population comprised 25 subjects each in active rTMS, sham rTMS, and healthy control groups. At baseline, cerebral hemodynamic indices were measured with transcranial Doppler sonography. Subjects in the active rTMS group received 10 sessions of rTMS daily; the sham group was administered sham rTMS with the same parameters. Cerebral hemodynamic parameters were repeated 5 minutes after the last rTMS session. At baseline, mean velocity (MV) of both middle cerebral artery (MCA; R-MCA: p=0.003; L-MCA: p=0.002) and anterior cerebral artery (ACA; R-ACA: p=0.003; L-ACA: p=.001) was significantly reduced. Pulsatility index (PI) of MCA (prTMS group, except L-MCA PI, significant differences were observed in values of MV, PI, and RI of both MCA and ACA following rTMS intervention; such changes were not evident in the sham rTMS group. The changes in mean difference in MV of L-MCA (p=0.006) and L-ACA (p=0.015) were statistically significant in the active rTMS group, in comparison with the sham group. Significant differences were also observed between the two groups postintervention, in RI of L-MCA (p=0.001) and ACA (R-ACA: p=0.010; L-ACA: p=0.015). Alcohol dependence may result in altered cerebral hemodynamic parameters, which can be improved with high-frequency rTMS application.
Jan Ohlberger; Rogers, Lauren A.; Nils Chr. Stenseth
2014-01-01
A persistent debate in population ecology concerns the relative importance of environmental stochasticity and density dependence in determining variability in adult year-class strength, which contributes to future reproduction as well as potential yield in exploited populations. Apart from the strength of the processes, the timing of density regulation may affect how stochastic variation, for instance through climate, translates into changes in adult abundance. In this study, we develop a lif...
Nagar, Lokesh; Dutta, Pankaj; Jain, Karuna
2014-05-01
In the present day business scenario, instant changes in market demand, different source of materials and manufacturing technologies force many companies to change their supply chain planning in order to tackle the real-world uncertainty. The purpose of this paper is to develop a multi-objective two-stage stochastic programming supply chain model that incorporates imprecise production rate and supplier capacity under scenario dependent fuzzy random demand associated with new product supply chains. The objectives are to maximise the supply chain profit, achieve desired service level and minimise financial risk. The proposed model allows simultaneous determination of optimum supply chain design, procurement and production quantities across the different plants, and trade-offs between inventory and transportation modes for both inbound and outbound logistics. Analogous to chance constraints, we have used the possibility measure to quantify the demand uncertainties and the model is solved using fuzzy linear programming approach. An illustration is presented to demonstrate the effectiveness of the proposed model. Sensitivity analysis is performed for maximisation of the supply chain profit with respect to different confidence level of service, risk and possibility measure. It is found that when one considers the service level and risk as robustness measure the variability in profit reduces.
Kim, Junhan; Marrone, Daniel P.; Chan, Chi-Kwan; Medeiros, Lia; Özel, Feryal; Psaltis, Dimitrios
2016-12-01
The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long-baseline interferometry (VLBI) experiment that is capable of observing black holes with horizon-scale resolution. Early observations have revealed variable horizon-scale emission in the Galactic Center black hole, Sagittarius A* (Sgr A*). Comparing such observations to time-dependent general relativistic magnetohydrodynamic (GRMHD) simulations requires statistical tools that explicitly consider the variability in both the data and the models. We develop here a Bayesian method to compare time-resolved simulation images to variable VLBI data, in order to infer model parameters and perform model comparisons. We use mock EHT data based on GRMHD simulations to explore the robustness of this Bayesian method and contrast it to approaches that do not consider the effects of variability. We find that time-independent models lead to offset values of the inferred parameters with artificially reduced uncertainties. Moreover, neglecting the variability in the data and the models often leads to erroneous model selections. We finally apply our method to the early EHT data on Sgr A*.
Patrizia Maria Carrieri
Full Text Available Methadone coverage is poor in many countries due in part to methadone induction being possible only in specialized care (SC. This multicenter pragmatic trial compared the effectiveness of methadone treatment between two induction models: primary care (PC and SC.In this study, registered at ClinicalTrials.Gov (NCT00657397, opioid-dependent individuals not on methadone treatment for at least one month or receiving buprenorphine but needing to switch were randomly assigned to start methadone in PC (N = 155 or in SC (N = 66 in 10 sites in France. Visits were scheduled at months M0, M3, M6 and M12. The primary outcome was self-reported abstinence from street-opioids at 12 months (M12 (with an underlying 15% non-inferiority hypothesis for PC. Secondary outcomes were abstinence during follow-up, engagement in treatment (i.e. completing the induction period, retention and satisfaction with the explanations provided by the physician. Primary analysis used intention to treat (ITT. Mixed models and the log-rank test were used to assess the arm effect (PC vs. SC on the course of abstinence and retention, respectively.In the ITT analysis (n = 155 in PC, 66 in SC, which compared the proportions of street-opioid abstinent participants, 85/155 (55% and 22/66 (33% of the participants were classified as street-opioid abstinent at M12 in PC and SC, respectively. This ITT analysis showed the non-inferiority of PC (21.5 [7.7; 35.3]. Engagement in treatment and satisfaction with the explanations provided by the physician were significantly higher in PC than SC. Retention in methadone and abstinence during follow-up were comparable in both arms (p = 0.47, p = 0.39, respectively.Under appropriate conditions, methadone induction in primary care is feasible and acceptable to both physicians and patients. It is as effective as induction in specialized care in reducing street-opioid use and ensuring engagement and retention in treatment for opioid dependence.Number Eudract
Thiery, Thimothée; Le Doussal, Pierre
2017-01-01
We consider the Beta polymer, an exactly solvable model of directed polymer on the square lattice, introduced by Barraquand and Corwin (BC) (2016 Probab. Theory Relat. Fields 1-16). We study the statistical properties of its point to point partition sum. The problem is equivalent to a model of a random walk in a time-dependent (and in general biased) 1D random environment. In this formulation, we study the sample to sample fluctuations of the transition probability distribution function (PDF) of the random walk. Using the Bethe ansatz we obtain exact formulas for the integer moments, and Fredholm determinant formulas for the Laplace transform of the directed polymer partition sum/random walk transition probability. The asymptotic analysis of these formulas at large time t is performed both (i) in a diffusive vicinity, x˜ {{t}1/2} , of the optimal direction (in space-time) chosen by the random walk, where the fluctuations of the PDF are found to be Gamma distributed; (ii) in the large deviations regime, x˜ t , of the random walk, where the fluctuations of the logarithm of the PDF are found to grow with time as t 1/3 and to be distributed according to the Tracy-Widom GUE distribution. Our exact results complement those of BC for the cumulative distribution function of the random walk in regime (ii), and in regime (i) they unveil a novel fluctuation behavior. We also discuss the crossover regime between (i) and (ii), identified as x˜ {{t}3/4} . Our results are confronted to extensive numerical simulations of the model.
Almond, Russell G.; Mulder, Joris; Hemat, Lisa A.; Yan, Duanli
2006-01-01
Bayesian network models offer a large degree of flexibility for modeling dependence among observables (item outcome variables) from the same task that may be dependent. This paper explores four design patterns for modeling locally dependent observations from the same task: (1) No context--Ignore dependence among observables; (2) Compensatory…
2014-04-09
Simulation-based Time-dependent Reliability Analysis for Composite Hydrokinetic Turbine Blades,” Structural and Multidisciplinary Optimization...Genetic Algorithm,” ASME Journal of Mechanical Design, 131(7). 13. Hu, Z., and Du, X., 2012, “Reliability Analysis for Hydrokinetic Turbine Blades...to Seismic Risk Based on Dynamic Analysis,” Journal of Engineering Mechanics, 129, 901- 917. 19. Beck, J. L., and Au, S. K., 2002, “Bayesian Updating
Cronin, C C
2012-02-03
Abnormalities of the renin-angiotensin system have been reported in patients with diabetes mellitus and with diabetic complications. In this study, plasma concentrations of prorenin, renin, and aldosterone were measured in a stratified random sample of 110 insulin-dependent (Type 1) diabetic patients attending our outpatient clinic. Fifty-four age- and sex-matched control subjects were also examined. Plasma prorenin concentration was higher in patients without complications than in control subjects when upright (geometric mean (95% confidence intervals (CI): 75.9 (55.0-105.6) vs 45.1 (31.6-64.3) mU I-1, p < 0.05). There was no difference in plasma prorenin concentration between patients without and with microalbuminuria and between patients without and with background retinopathy. Plasma renin concentration, both when supine and upright, was similar in control subjects, in patients without complications, and in patients with varying degrees of diabetic microangiopathy. Plasma aldosterone was suppressed in patients without complications in comparison to control subjects (74 (58-95) vs 167 (140-199) ng I-1, p < 0.001) and was also suppressed in patients with microvascular disease. Plasma potassium was significantly higher in patients than in control subjects (mean +\\/- standard deviation: 4.10 +\\/- 0.36 vs 3.89 +\\/- 0.26 mmol I-1; p < 0.001) and plasma sodium was significantly lower (138 +\\/- 4 vs 140 +\\/- 2 mmol I-1; p < 0.001). We conclude that plasma prorenin is not a useful early marker for diabetic microvascular disease. Despite apparently normal plasma renin concentrations, plasma aldosterone is suppressed in insulin-dependent diabetic patients.
Distance and Azimuthal Dependence of Ground‐Motion Variability for Unilateral Strike‐Slip Ruptures
Vyas, Jagdish Chandra
2016-06-21
We investigate near‐field ground‐motion variability by computing the seismic wavefield for five kinematic unilateral‐rupture models of the 1992 Mw 7.3 Landers earthquake, eight simplified unilateral‐rupture models based on the Landers event, and a large Mw 7.8 ShakeOut scenario. We include the geometrical fault complexity and consider different 1D velocity–density profiles for the Landers simulations and a 3D heterogeneous Earth structure for the ShakeOut scenario. For the Landers earthquake, the computed waveforms are validated using strong‐motion recordings. We analyze the simulated ground‐motion data set in terms of distance and azimuth dependence of peak ground velocity (PGV). Our simulations reveal that intraevent ground‐motion variability Graphic is higher in close distances to the fault (<20 km) and decreases with increasing distance following a power law. This finding is in stark contrast to constant sigma‐values used in empirical ground‐motion prediction equations. The physical explanation of a large near‐field Graphic is the presence of strong directivity and rupture complexity. High values of Graphic occur in the rupture‐propagation direction, but small values occur in the direction perpendicular to it. We observe that the power‐law decay of Graphic is primarily controlled by slip heterogeneity. In addition, Graphic, as function of azimuth, is sensitive to variations in both rupture speed and slip heterogeneity. The azimuth dependence of the ground‐motion mean μln(PGV) is well described by a Cauchy–Lorentz function that provides a novel empirical quantification to model the spatial dependency of ground motion. Online Material: Figures of slip distributions, residuals to ground‐motion prediction equations (GMPEs), distance and azimuthal dependence, and directivity predictor of ground‐motion variability for different source models.
无
2007-01-01
In this article, the dependent steps of a negative drift random walk are modelled as a two-sided linear process Xn =-μ+∞∑j=-∞ψn-jεj, where {ε, εn; -∞＜ n ＜ +∞}is a sequence of independent, identically distributed random variables with zero mean, μ＞0 is a constant and the coefficients {ψi;-∞＜ i ＜∞} satisfy 0 ＜∞∑j=-∞|jψj| ＜∞. Under the conditions that the distribution function of |ε| has dominated variation and ε satisfies certain tail balance conditions, the asymptotic behavior of P{supn≥0(-nμ+∞∑j=-∞εjβnj) ＞ x}is discussed. Then the result is applied to ultimate ruin probability.
Modeling of stochastic dynamics of time-dependent flows under high-dimensional random forcing
Babaee, Hessam; Karniadakis, George
2016-11-01
In this numerical study the effect of high-dimensional stochastic forcing in time-dependent flows is investigated. To efficiently quantify the evolution of stochasticity in such a system, the dynamically orthogonal method is used. In this methodology, the solution is approximated by a generalized Karhunen-Loeve (KL) expansion in the form of u (x , t ω) = u ̲ (x , t) + ∑ i = 1 N yi (t ω)ui (x , t) , in which u ̲ (x , t) is the stochastic mean, the set of ui (x , t) 's is a deterministic orthogonal basis and yi (t ω) 's are the stochastic coefficients. Explicit evolution equations for u ̲ , ui and yi are formulated. The elements of the basis ui (x , t) 's remain orthogonal for all times and they evolve according to the system dynamics to capture the energetically dominant stochastic subspace. We consider two classical fluid dynamics problems: (1) flow over a cylinder, and (2) flow over an airfoil under up to one-hundred dimensional random forcing. We explore the interaction of intrinsic with extrinsic stochasticity in these flows. DARPA N66001-15-2-4055, Office of Naval Research N00014-14-1-0166.
Burke, J J
1990-06-01
The relationship between the thermal dependence of the reappearance of chlorophyll variable fluorescence following illumination and temperature dependence of the apparent Michaelis constant (K(m)) of NADH hydroxypyruvate reductase for NADH was investigated in cool and warm season plant species. Brancker SF-20 and SF-30 fluorometers were used to evaluate induced fluorescence transients from detached leaves of wheat (Triticum aestivum L. cv TAM-101), cotton (Gossypium hirsutum L. cv Paymaster 145), tomato (Lycopersicon esculentum cv Del Oro), bell pepper (Capsicum annuum L. cv California Wonder), and petunia (Petunia hybrida cv. Red Sail). Following an illumination period at 25 degrees C, the reappearance of variable fluorescence during a dark incubation was determined at 5 degrees C intervals from 15 degrees C to 45 degrees C. Variable fluorescence recovery was normally distributed with the maximum recovery observed at 20 degrees C in wheat, 30 degrees C in cotton, 20 degrees C to 25 degrees C in tomato, 30 to 35 degrees C in bell pepper and 25 degrees C in petunia. Comparison of the thermal response of fluorescence recovery with the temperature sensitivity of the apparent K(m) of hydroxypyruvate reductase for NADH showed that the range of temperatures providing fluorescence recovery corresponded with those temperatures providing the minimum apparent K(m) values (viz. the thermal kinetic window).
Chaibub Neto, Elias
2016-11-01
Clinical trials traditionally employ blinding as a design mechanism to reduce the influence of placebo effects. In practice, however, it can be difficult or impossible to blind study participants and unblinded trials are common in medical research. Here we show how instrumental variables can be used to quantify and disentangle treatment and placebo effects in randomized clinical trials comparing control and active treatments in the presence of confounders. The key idea is to use randomization to separately manipulate treatment assignment and psychological encouragement conversations/interactions that increase the participants’ desire for improved symptoms. The proposed approach is able to improve the estimation of treatment effects in blinded studies and, most importantly, opens the doors to account for placebo effects in unblinded trials.
Heart rate variability and skin conductance biofeedback: A triple-blind randomized controlled study
Raaijmakers, S.F.; Steel,F.W.; Goede, M. de; Wouwe, N.C. van; Erp, J.B.F. van; Brouwer, A.M.
2013-01-01
High heart rate variability (HRV) and low skin conductance level (SCL) have been associated with low levels of stress. Biofeedback - providing an individual with online information about his or her own physiological state – may help to change these signals in the desired direction and therewith impr
Degree of multicollinearity and variables involved in linear dependence in additive-dominant models
Juliana Petrini
2012-12-01
Full Text Available The objective of this work was to assess the degree of multicollinearity and to identify the variables involved in linear dependence relations in additive-dominant models. Data of birth weight (n=141,567, yearling weight (n=58,124, and scrotal circumference (n=20,371 of Montana Tropical composite cattle were used. Diagnosis of multicollinearity was based on the variance inflation factor (VIF and on the evaluation of the condition indexes and eigenvalues from the correlation matrix among explanatory variables. The first model studied (RM included the fixed effect of dam age class at calving and the covariates associated to the direct and maternal additive and non-additive effects. The second model (R included all the effects of the RM model except the maternal additive effects. Multicollinearity was detected in both models for all traits considered, with VIF values of 1.03 - 70.20 for RM and 1.03 - 60.70 for R. Collinearity increased with the increase of variables in the model and the decrease in the number of observations, and it was classified as weak, with condition index values between 10.00 and 26.77. In general, the variables associated with additive and non-additive effects were involved in multicollinearity, partially due to the natural connection between these covariables as fractions of the biological types in breed composition.
Ohlberger, Jan; Rogers, Lauren A; Stenseth, Nils Chr
2014-01-01
A persistent debate in population ecology concerns the relative importance of environmental stochasticity and density dependence in determining variability in adult year-class strength, which contributes to future reproduction as well as potential yield in exploited populations. Apart from the strength of the processes, the timing of density regulation may affect how stochastic variation, for instance through climate, translates into changes in adult abundance. In this study, we develop a life-cycle model for the population dynamics of a large marine fish population, Northeast Arctic cod, to disentangle the effects of density-independent and density-dependent processes on early life-stages, and to quantify the strength of compensatory density dependence in the population. The model incorporates information from scientific surveys and commercial harvest, and dynamically links multiple effects of intrinsic and extrinsic factors on all life-stages, from eggs to spawners. Using a state-space approach we account for observation error and stochasticity in the population dynamics. Our findings highlight the importance of density-dependent survival in juveniles, indicating that this period of the life cycle largely determines the compensatory capacity of the population. Density regulation at the juvenile life-stage dampens the impact of stochastic processes operating earlier in life such as environmental impacts on the production of eggs and climate-dependent survival of larvae. The timing of stochastic versus regulatory processes thus plays a crucial role in determining variability in adult abundance. Quantifying the contribution of environmental stochasticity and compensatory mechanisms in determining population abundance is essential for assessing population responses to climate change and exploitation by humans.
The dependence of J/ψ-nucleon inelastic cross section on the Feynman variable
DUAN Chun-Gui; LIU Na; MIAO Wen-Dan
2011-01-01
By means of two typical sets of nuclear parton distribution functions,meanwhile taking account of the energy loss of the beam proton and the nuclear absorption of the charmonium states traversing the nuclear matter in the uniform framework of the Glauber model,a leading order phenomenological analysis is given in the color evaporation model of the E866 experimental data on J/Ψ production differential cross section ratios RFe/Be(xF).It is shown that the energy loss effect of beam proton on RFe/Be(xF)is more important than the nuclear effects on parton distribution functions in the high Feynman variable xF region.It is found that the J/Ψ-nucleon inelastic cross section depends on the Feynman variable XF and increases linearly with XF in the region xF > 0.2.
Li Xin ZHANG
2002-01-01
Let {X, Xa; X-n;-n∈ Nd} be a field of i.i.d. random variables indexed by d-tuples of positiveintegers and taking values in a Banach spaceB and let X(r)-n = X-m if ‖X-m‖ is the r-th maximum ofsums (r)S-n by a Brownian sheet and obtain sufficient and necessary conditions for (r)S-n to satisfy thecompact and functional laws of the iterated logarithm. These results improve the previous works byMorrow (1981), Li and Wu (1989) and Ledoux and Talagrand (1990).
Wang, Kezhi
2014-09-01
The sum of ratios of products of independent 2642 2642α-μ random variables (RVs) is approximated by using the Generalized Gamma ratio approximation (GGRA) with Gamma ratio approximation (GRA) as a special case. The proposed approximation is used to calculate the outage probability of the equal gain combining (EGC) or maximum ratio combining (MRC) receivers for wireless multihop relaying or multiple scattering systems considering interferences. Numerical results show that the newly derived approximation works very well verified by the simulation, while GRA has a slightly worse performance than GGRA when outage probability is below 0.1 but with a more simplified form.
Mennen, L.; Maat, M. de; Meijer, G.; Zock, P.; Grobbee, D.; Kok, F.; Kluft, C.; Schouten, E.
1998-01-01
A fat-rich meal increases activated factor VII (FVIIa), but it is not clear whether this increase depends on the fatty acid composition of the meal. Therefore, we studied the FVIIa response to fat-rich meals with different fatty acid composition in a randomized controlled crossover trial and investi
McKay, James R.; Van Horn, Deborah H. A.; Oslin, David W.; Lynch, Kevin G.; Ivey, Megan; Ward, Kathleen; Drapkin, Michelle L.; Becher, Julie R.; Coviello, Donna M.
2010-01-01
Objective: The study tested whether adding up to 18 months of telephone continuing care, either as monitoring and feedback (TM) or longer contacts that included counseling (TMC), to intensive outpatient programs (IOPs) improved outcomes for alcohol-dependent patients. Method: Participants (N = 252) who completed 3 weeks of IOP were randomized to…
Williamson, Brenda D.; Campbell-Whatley, Gloria D.; Lo, Ya-yu
2009-01-01
Group contingencies have the advantages of encouraging individual students to collectively feel responsible for appropriate and inappropriate classroom behaviors and have shown effectiveness in improving students' behavior. The purpose of this study was to investigate the effects of a random dependent group contingency on the on-task behaviors of…
Flueck, Joelle Leonie; Schaufelberger, Fabienne; Lienert, Martina; Schäfer Olstad, Daniela; Wilhelm, Matthias; Perret, Claudio
2016-01-01
Caffeine increases sympathetic nerve activity in healthy individuals. Such modulation of nervous system activity can be tracked by assessing the heart rate variability. This study aimed to investigate the influence of caffeine on time- and frequency-domain heart rate variability parameters, blood pressure and tidal volume in paraplegic and tetraplegic compared to able-bodied participants. Heart rate variability was measured in supine and sitting position pre and post ingestion of either placebo or 6 mg caffeine in 12 able-bodied, 9 paraplegic and 7 tetraplegic participants in a placebo-controlled, randomized and double-blind study design. Metronomic breathing was applied (0.25 Hz) and tidal volume was recorded during heart rate variability assessment. Blood pressure, plasma caffeine and epinephrine concentrations were analyzed pre and post ingestion. Most parameters of heart rate variability did not significantly change post caffeine ingestion compared to placebo. Tidal volume significantly increased post caffeine ingestion in able-bodied (p = 0.021) and paraplegic (p = 0.036) but not in tetraplegic participants (p = 0.34). Systolic and diastolic blood pressure increased significantly post caffeine in able-bodied (systolic: p = 0.003; diastolic: p = 0.021) and tetraplegic (systolic: p = 0.043; diastolic: p = 0.042) but not in paraplegic participants (systolic: p = 0.09; diastolic: p = 0.33). Plasma caffeine concentrations were significantly increased post caffeine ingestion in all three groups of participants (p<0.05). Plasma epinephrine concentrations increased significantly in able-bodied (p = 0.002) and paraplegic (p = 0.032) but not in tetraplegic participants (p = 0.63). The influence of caffeine on the autonomic nervous system seems to depend on the level of lesion and the extent of the impairment. Therefore, tetraplegic participants may be less influenced by caffeine ingestion. Trial Registration ClinicalTrials.gov NCT02083328 PMID:27776149
Krøigård, Thomas; Gaist, David; Otto, Marit;
2014-01-01
. Peroneal nerve distal motor latency, motor conduction velocity, and compound motor action potential amplitude; sural nerve sensory action potential amplitude and sensory conduction velocity; and tibial nerve minimal F-wave latency were examined in 51 healthy subjects, aged 40 to 67 years. They were...... reexamined after 2 and 26 weeks. There was no change in the variables except for a minor decrease in sural nerve sensory action potential amplitude and a minor increase in tibial nerve minimal F-wave latency. Reproducibility was best for peroneal nerve distal motor latency and motor conduction velocity...
Truong D Nguyen-Huu
2015-07-01
Full Text Available Modulation of gene network activity allows cells to respond to changes in environmental conditions. For example, the galactose utilization network in Saccharomyces cerevisiae is activated by the presence of galactose but repressed by glucose. If both sugars are present, the yeast will first metabolize glucose, depleting it from the extracellular environment. Upon depletion of glucose, the genes encoding galactose metabolic proteins will activate. Here, we show that the rate at which glucose levels are depleted determines the timing and variability of galactose gene activation. Paradoxically, we find that Gal1p, an enzyme needed for galactose metabolism, accumulates more quickly if glucose is depleted slowly rather than taken away quickly. Furthermore, the variability of induction times in individual cells depends non-monotonically on the rate of glucose depletion and exhibits a minimum at intermediate depletion rates. Our mathematical modeling suggests that the dynamics of the metabolic transition from glucose to galactose are responsible for the variability in galactose gene activation. These findings demonstrate that environmental dynamics can determine the phenotypic outcome at both the single-cell and population levels.
A Directed Continuous Time Random Walk Model with Jump Length Depending on Waiting Time
Long Shi
2014-01-01
Full Text Available In continuum one-dimensional space, a coupled directed continuous time random walk model is proposed, where the random walker jumps toward one direction and the waiting time between jumps affects the subsequent jump. In the proposed model, the Laplace-Laplace transform of the probability density function P(x,t of finding the walker at position x at time t is completely determined by the Laplace transform of the probability density function φ(t of the waiting time. In terms of the probability density function of the waiting time in the Laplace domain, the limit distribution of the random process and the corresponding evolving equations are derived.
Saddlepoint approximation based structural reliability analysis with non-normal random variables
无
2010-01-01
The saddlepoint approximation (SA) can directly estimate the probability distribution of linear performance function in non-normal variables space. Based on the property of SA, three SA based methods are developed for the structural system reliability analysis. The first method is SA based reliability bounds theory (RBT), in which SA is employed to estimate failure probability and equivalent normal reliability index for each failure mode firstly, and then RBT is employed to obtain the upper and the lower bounds of system failure probability. The second method is SA based Nataf approximation, in which SA is used to estimate the probability density function (PDF) and cumulative distribution function (CDF) for the approximately linearized performance function of each failure mode. After the PDF of each failure mode and the correlation coefficients among approximately linearized performance functions are estimated, Nataf distribution is employed to approximate the joint PDF of multiple structural system performance functions, and then the system failure probability can be estimated directly by numerical simulation using the joint PDF. The third method is SA based line sampling (LS). The standardization transformation is needed to eliminate the dimensions of variables firstly in this case. Then LS method can express the system failure probability as an arithmetic average of a set of failure probabilities of the linear performance functions, and the probabilities of the linear performance functions can be estimated by the SA in the non-normal variables space. By comparing basic concepts, implementations and results of illustrations, the following conclusions can be drawn: (1) The first method can only obtain the bounds of system failure probability and it is only acceptable for the linear limit state function; (2) the second method can give the estimation of system failure probability, and its error mostly results from the approximation of Nataf distribution for the
Limitations on the recovery of the true AGN variability parameters using Damped Random Walk modeling
Kozłowski, Szymon
2016-01-01
Context: The damped random walk (DRW) stochastic process is nowadays frequently used to model aperiodic light curves of AGNs. A number of correlations between the DRW model parameters, the signal decorrelation timescale and amplitude, and the physical AGN parameters such as the black hole mass or luminosity have been reported. Aims: We are interested in whether it is plausible to correctly measure the DRW parameters from a typical ground-based survey, in particular how accurate the recovered DRW parameters are compared to the input ones. Methods: By means of Monte Carlo simulations of AGN light curves, we study the impact of the light curve length, the source magnitude, cadence, and additional light on the DRW model parameters. Results: The most significant finding is that currently existing surveys are going to return unconstrained DRW decorrelation timescales, because typical rest-frame data do not probe long enough timescales or the white noise part of PSD for DRW. The experiment length must be at least te...
The Timescale-Dependent Color Variability of Quasars Viewed with GALEX
Zhu, Fei-Fan; Cai, Zhen-Yi; Sun, Yu-Han
2016-01-01
In recent work done by Sun et. al., the color variation of quasars, namely the bluer-when-brighter trend, was found to be timescale-dependent using SDSS $g/r$ band light curves in the Stripe 82. Such timescale dependence, i.e., bluer variation at shorter timescales, supports the thermal fluctuation origin of the UV/optical variation in quasars, and can be well modeled with the inhomogeneous accretion disk model. In this paper, we extend the study to much shorter wavelengths in the rest frame (down to extreme UV), using GALaxy Evolution eXplorer (GALEX) photometric data of quasars collected in two ultraviolet bands (near-UV and far-UV). We develop Monte-Carlo simulations to correct possible biases due to the considerably larger photometric uncertainties in GALEX light curves (particularly in far-UV, comparing with SDSS $g/r$ bands), which otherwise could produce artificial results. We securely confirm the previously discovered timescale dependence of the color variability with independent datasets and at short...
Cast microstructure of Inconel 713C and its dependence on solidification variables
Bhambri, A.K.; Kattamis, T.Z.; Morral, J.E.
1975-03-01
The dependence of cast microstructure of Inconel 713C on solidification variables was investigated over a wide range of local cooling rates, epsilon, and thermal gradients in the liquid at the solid-liquid interface, G. The shape of MC carbide particles was found to depend greatly on: 1) the G/R ratio at the solid-liquid interface, where R is growth rate, through the effect of this ratio on the solid phase, ..gamma../sub g/, growth morphology. Under planar front growth conditions the carbide particles were octahedral, under cellular growth conditions they were plate-like, elongated along the cellular growth direction, and under dendritic growth conditions they were irregularly shaped; 2) the local cooling rate, epsilon, when ..gamma.. was dendritic, with a transition from octahedral to dendritic with increasing epsilon. The size of MC carbide particles was found to be controlled by coarsening and to become finer with increasing epsilon. In this alloy the composition of the MC carbide was established as (Nb/sub 0/./sub 63/Ti/sub 0/./sub 31/M0/sub 0/./sub 06/)C and was practically independent of local cooling rate. Other observations were that the precipitation of ..gamma.., d the formation of nonequilibrium eutectics, such as MC-..gamma.., ..gamma..-..gamma..' or MC-..gamma..-..gamma..' were suppressed at splat-cooling rates. Also, microsegregation of all alloying elements with the exception of aluminum was normal, with concentration increasing from the dendrite center-line to the dendrite arm boundary. Aluminum behaved in the opposite manner. Within the cooling rate range used herein, this variable had only a slight effect on microsegregation.
Bhargava, Kapilesh, E-mail: kapil_66@barc.gov.i [Architecture and Civil Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Mori, Yasuhiro [Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8603 (Japan); Ghosh, A.K. [Reactor Safety Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)
2011-05-15
This paper forms the third part of a study which addresses time-dependent reliability analyses of reinforced concrete (RC) beams affected by reinforcement corrosion. Parts 1 and 2 of the reliability study are presented in companion papers. Part 1 of the reliability study presents evaluation of probabilistic descriptions for time-dependent strengths of a typical simply supported corrosion-affected RC beam. These probabilistic descriptions, i.e., mean and coefficient of variation (c.o.v.) for the time-dependent strengths are presented for two limit states: (a) flexural failure; and (b) shear failure. Part 2 of the reliability study presents evaluation of time-dependent failure probability for the considered RC beam by utilizing the information on probabilistic descriptions for time-dependent strengths available in Part 1. Evaluation of time-dependent failure probability considering the variability in time-dependent strengths and/or time-dependent degradation functions is also presented. This paper investigates the effects of time to corrosion initiation and its variability on failure probability of the same RC beam presented in companion papers. By considering variability in the identified variables that could affect the expected time of first corrosion, simple estimations are presented for mean time to corrosion initiation and variability associated with time to corrosion initiation. Evaluation of time-dependent failure probability for the beam is presented by considering estimated probabilistic descriptions, i.e., mean and c.o.v. for time to corrosion initiation. Parametric analyses show that failure probability for the beam is sensitive to the mode of strength degradation and time to corrosion initiation.
Precise lim sup behavior of probabilities of large deviations for sums of i.i.d. random variables
Andrew Rosalsky
2004-12-01
Full Text Available Let {X,Xn;nÃ¢Â‰Â¥1} be a sequence of real-valued i.i.d. random variables and let Sn=Ã¢ÂˆÂ‘i=1nXi, nÃ¢Â‰Â¥1. In this paper, we study the probabilities of large deviations of the form P(Sn>tn1/p, P(Sntn1/p, where t>0 and 0x1/p/ÃÂ•(x=1, then for every t>0, limsupnÃ¢Â†Â’Ã¢ÂˆÂžP(|Sn|>tn1/p/(nÃÂ•(n=tpÃŽÂ±.
ZHENGZUKANG
1996-01-01
Suppose that Z1,Z2…,Zn are independent normal random variables with common mean μ and variance σ2. Then S2=∑n n=1 (zi-z)2/σ2 and T =（n-1的平方根）-Z/（S2/n的平方根） have x2n-1 distribution and tn-1 distribution respectively. If the normal assumption fails, there will be the remainders of the distribution functions and density functions. This paper gives the direct expansions of distribution functions and density functions of S2 and T up to o(n-1). They are more intuitive and convenient than usual Edgeworth expansions.
Nam, Sungsik
2010-11-01
Order statistics find applications in various areas of communications and signal processing. In this paper, we introduce an unified analytical framework to determine the joint statistics of partial sums of ordered random variables (RVs). With the proposed approach, we can systematically derive the joint statistics of any partial sums of ordered statistics, in terms of the moment generating function (MGF) and the probability density function (PDF). Our MGF-based approach applies not only when all the K ordered RVs are involved but also when only the Ks(Ks < K) best RVs are considered. In addition, we present the closed-form expressions for the exponential RV special case. These results apply to the performance analysis of various wireless communication systems over fading channels. © 2006 IEEE.
Pechacek, Tomas; Karas, Vladimir; Czerny, Bozena; Dovciak, Michal
2013-01-01
We study some general properties of accretion disc variability in the context of stationary random processes. In particular, we are interested in mathematical constraints that can be imposed on the functional form of the Fourier power-spectrum density (PSD) that exhibits a multiply broken shape and several local maxima. We develop a methodology for determining the regions of the model parameter space that can in principle reproduce a PSD shape with a given number and position of local peaks and breaks of the PSD slope. Given the vast space of possible parameters, it is an important requirement that the method is fast in estimating the PSD shape for a given parameter set of the model. We generated and discuss the theoretical PSD profiles of a shot-noise-type random process with exponentially decaying flares. Then we determined conditions under which one, two, or more breaks or local maxima occur in the PSD. We calculated positions of these features and determined the changing slope of the model PSD. Furthermor...
Verikas, A; Gelzinis, A; Vaiciukynas, E; Bacauskiene, M; Minelga, J; Hållander, M; Uloza, V; Padervinskis, E
2015-02-01
Comprehensive evaluation of results obtained using acoustic and contact microphones in screening for laryngeal disorders through analysis of sustained phonation is the main objective of this study. Aiming to obtain a versatile characterization of voice samples recorded using microphones of both types, 14 different sets of features are extracted and used to build an accurate classifier to distinguish between normal and pathological cases. We propose a new, data dependent random forests-based, way to combine information available from the different feature sets. An approach to exploring data and decisions made by a random forest is also presented. Experimental investigations using a mixed gender database of 273 subjects have shown that the perceptual linear predictive cepstral coefficients (PLPCC) was the best feature set for both microphones. However, the linear predictive coefficients (LPC) and linear predictive cosine transform coefficients (LPCTC) exhibited good performance in the acoustic microphone case only. Models designed using the acoustic microphone data significantly outperformed the ones built using data recorded by the contact microphone. The contact microphone did not bring any additional information useful for the classification. The proposed data dependent random forest significantly outperformed the traditional random forest.
Random functions and turbulence
Panchev, S
1971-01-01
International Series of Monographs in Natural Philosophy, Volume 32: Random Functions and Turbulence focuses on the use of random functions as mathematical methods. The manuscript first offers information on the elements of the theory of random functions. Topics include determination of statistical moments by characteristic functions; functional transformations of random variables; multidimensional random variables with spherical symmetry; and random variables and distribution functions. The book then discusses random processes and random fields, including stationarity and ergodicity of random
R. Wagner
2011-09-01
Full Text Available We present computational results on the shape dependency of the extinction and absorption cross sections of dustlike aerosol particles that were modeled as randomly oriented spheroids. Shape dependent variations in the extinction cross sections are largest in the size regime that is governed by the interference structure. Elongated spheroids best fitted measured extinction spectra of re-dispersed Saharan dust samples. For dust particles smaller than 1.5 μm in diameter and low absorption potential, shape effects on the absorption cross sections are very small.
Lin, I-Mei; Fan, Sheng-Yu; Lu, Hsueh-Chen; Lin, Tsung-Hsien; Chu, Chih-Sheng; Kuo, Hsuan-Fu; Lee, Chee-Siong; Lu, Ye-Hsu
2015-07-01
Hostility is a psychosocial risk factor that may decrease heart rate variability (HRV) in coronary artery disease (CAD) through cardiac autonomic imbalance. Heart rate variability biofeedback (HRV-BF) increases HRV indices and baroreflex gain. This study examines the effectiveness of HRV-BF in restoring cardiac autonomic balance and decreasing hostility among patients with CAD. One hundred and fifty-four patients with CAD were assigned randomly to receive 6 weeks of HRV-BF, in addition to the standard medical care received by the wait-list control (WLC) group. A 5-min electrocardiogram, blood pressure, and hostility were assessed pre-intervention, post-intervention, and at 1-month follow-up. The standard deviation of normal-to-normal intervals (SDNN), low frequency (LF), and log LF at post-intervention was significantly higher than that at pre-intervention in the HRV-BF group. Baseline log LF was significantly higher post-intervention and at follow-up after HRV-BF training than at pre-intervention. The treatment curve of log LF pre-session increased significantly after session 2, which was maintained to post-intervention. Expressive hostility, suppressive hostility, and hostility total score at post-intervention and one-month follow-up after HRV-BF were significantly lower than at pre-intervention. This study showed increased HRV and decreased expressive and suppressive hostility behavior in patients with CAD following HRV-BF.
Gottfredson, Nisha C; Sterba, Sonya K; Jackson, Kristina M
2017-01-01
Random coefficient-dependent (RCD) missingness is a non-ignorable mechanism through which missing data can arise in longitudinal designs. RCD, for which we cannot test, is a problematic form of missingness that occurs if subject-specific random effects correlate with propensity for missingness or dropout. Particularly when covariate missingness is a problem, investigators typically handle missing longitudinal data by using single-level multiple imputation procedures implemented with long-format data, which ignores within-person dependency entirely, or implemented with wide-format (i.e., multivariate) data, which ignores some aspects of within-person dependency. When either of these standard approaches to handling missing longitudinal data is used, RCD missingness leads to parameter bias and incorrect inference. We explain why multilevel multiple imputation (MMI) should alleviate bias induced by a RCD missing data mechanism under conditions that contribute to stronger determinacy of random coefficients. We evaluate our hypothesis with a simulation study. Three design factors are considered: intraclass correlation (ICC; ranging from .25 to .75), number of waves (ranging from 4 to 8), and percent of missing data (ranging from 20 to 50%). We find that MMI greatly outperforms the single-level wide-format (multivariate) method for imputation under a RCD mechanism. For the MMI analyses, bias was most alleviated when the ICC is high, there were more waves of data, and when there was less missing data. Practical recommendations for handling longitudinal missing data are suggested.
Elena Ricart; Maria Esteve; Montserrat Andreu; Francesc Casellas; David Monfort; Miquel Sans; Natalia Oudovenko; Raúl Lafuente; Julián Panés
2007-01-01
AIM: To evaluate the efficacy of 5 compared to 10 granulocyteaphaeresis sessions in patients with active steroid-dependent ulcerative colitis.METHODS: In this pilot, prospective, multicenter randomized trial, 20 patients with moderately active steroid-dependent ulcerative colitis were randomized to 5 or 10 granulocyteaphaeresis sessions. The primary objective was clinical remission at wk 17. Secondary measures included endoscopic remission and steroid consumption.RESULTS: Nine patients were randomized to 5 granulocyteaphaeresis sessions (group 1) and L1 patients to 10 granulocyteaphaeresis sessions (group 2). At wk 17, 37.5% of patients in group 1 and 45.45% of patients in group 2 were in clinical remission. Clinical remission was accompanied by endoscopic remission in all cases.Eighty-six percent of patients achieving remission were steroid-free at wk 17. Daily steroid requirements were significantly lower in group 2. Eighty-nine per cent of patients remained in remission during a one year follow-up. One serious adverse event, not related to the study therapy, was reported.CONCLUSION: Granulocyteaphaeresis is safe and effective for the treatment of steroid-dependent ulcerative colitis. In this population, increasing the number of aphaeresis sessions is not associated with higher remission rates, but affords a significant steroid-sparing effect.
Degree-degree dependencies in random graphs with heavy-tailed degrees
Hofstad, van der Remco; Litvak, Nelly
2014-01-01
Mixing patterns in large self-organizing networks, such as the Internet, the World Wide Web, social, and biological networks are often characterized by degree-degree dependencies between neighboring nodes. In assortative networks, the degree-degree dependencies are positive (nodes with similar degre
Müller, Christian A; Geisel, Olga; Pelz, Patricia; Higl, Verena; Krüger, Josephine; Stickel, Anna; Beck, Anne; Wernecke, Klaus-Dieter; Hellweg, Rainer; Heinz, Andreas
2015-08-01
Previous randomized, placebo-controlled trials (RCTs) assessing the efficacy of the selective γ-aminobutyric acid (GABA)-B receptor agonist baclofen in the treatment of alcohol dependence have reported divergent results, possibly related to the low to medium dosages of baclofen used in these studies (30-80mg/d). Based on preclinical observations of a dose-dependent effect and positive case reports in alcohol-dependent patients, the present RCT aimed to assess the efficacy and safety of individually titrated high-dose baclofen for the treatment of alcohol dependence. Out of 93 alcohol-dependent patients initially screened, 56 were randomly assigned to a double-blind treatment with individually titrated baclofen or placebo using dosages of 30-270mg/d. The multiple primary outcome measures were (1) total abstinence and (2) cumulative abstinence duration during a 12-week high-dose phase. More patients of the baclofen group maintained total abstinence during the high-dose phase than those receiving placebo (15/22, 68.2% vs. 5/21, 23.8%, p=0.014). Cumulative abstinence duration was significantly higher in patients given baclofen compared to patients of the placebo group (mean 67.8 (SD 30) vs. 51.8 (SD 29.6) days, p=0.047). No drug-related serious adverse events were observed during the trial. Individually titrated high-dose baclofen effectively supported alcohol-dependent patients in maintaining alcohol abstinence and showed a high tolerability, even in the event of relapse. These results provide further evidence for the potential of baclofen, thereby possibly extending the current pharmacological treatment options in alcohol dependence.
Nosedal-Sanchez, Alvaro; Jackson, Charles S.; Huerta, Gabriel
2016-07-01
A new test statistic for climate model evaluation has been developed that potentially mitigates some of the limitations that exist for observing and representing field and space dependencies of climate phenomena. Traditionally such dependencies have been ignored when climate models have been evaluated against observational data, which makes it difficult to assess whether any given model is simulating observed climate for the right reasons. The new statistic uses Gaussian Markov random fields for estimating field and space dependencies within a first-order grid point neighborhood structure. We illustrate the ability of Gaussian Markov random fields to represent empirical estimates of field and space covariances using "witch hat" graphs. We further use the new statistic to evaluate the tropical response of a climate model (CAM3.1) to changes in two parameters important to its representation of cloud and precipitation physics. Overall, the inclusion of dependency information did not alter significantly the recognition of those regions of parameter space that best approximated observations. However, there were some qualitative differences in the shape of the response surface that suggest how such a measure could affect estimates of model uncertainty.
Bingi, Jayachandra; Nair, Radhika V.; Vijayan, C.
2017-02-01
Light propagation and localization in a random structure with a periodic background is an upcoming paradigm for novel photonic applications. This paper demonstrates the phenomenon of time dependent transmittance of evanescent Bloch modes (EBM) in ZnS random photonic crystal (RPC) which forms the basis for photonic delay switching. The RPC is fabricated by colloidal self-assembly with ZnS nanospheres of size 215 nm. An anomalous reciprocity and time dependent transmission at EBM (mid band gap wavelength) are observed in coherent back scattering and transmission studies respectively. These are explained on the basis of restricted propagation of EBMs through random channels in the periodic background and enhanced field storage inside RPC. The channelized propagation of EBMs is evident from decreasing time delay of transmittance at reduced thicknesses. The proportionality between transmission time delay and incident power confirms photon (field) storage within the RPC. The results indicate that structures with systematically engineered EBM channels can work as wavelength selective delay switch and further provide a short time photon storage system under non-absorbing conditions.
Akbar, Noreen Sher; Abid, Syed Ali; Tripathi, Dharmendra; Mir, Nazir Ahmed
2017-03-01
The transport of single-wall carbon nanotube (CNT) nanofluids with temperature-dependent variable viscosity is analyzed by peristaltically driven flow. The main flow problem has been modeled using cylindrical coordinates and flow equations are simplified to ordinary differential equations using long wavelength and low Reynolds' number approximation. Analytical solutions have been obtained for axial velocity, pressure gradient and temperature. Results acquired are discussed graphically for better understanding. It is observed that with an increment in the Grashof number the velocity of the governing fluids starts to decrease significantly and the pressure gradient is higher for pure water as compared to single-walled carbon nanotubes due to low density. As the specific heat is very high for pure water as compared to the multi-wall carbon nanotubes, it raises temperature of the muscles, in the case of pure water, as compared to the multi-walled carbon nanotubes. Furthermore, it is noticed that the trapped bolus starts decreasing in size as the buoyancy forces are dominant as compared to viscous forces. This model may be applicable in biomedical engineering and nanotechnology to design the biomedical devices.
M. Kaloc; S. Bartusek; S. Czudek [VSB-TU Ostrava (Czech Republic)
2005-07-01
The main sources for this report are the experiences acquired by the long lasting practice of the coking coal mixes preparing and tuning them in accordance with the variable qualitative properties of the coals mined in the coalfields of the OKD Company Ostrava. The systematic database, made by summarizing the values of measured indexes, became a very useful instrument for the coal mixes composing with regard on the two today very important points of view, namely: Contemporary presence and the long lasting availability of the definite coal type from any local source. Price basis influencing strongly the economics of the coke production. The method of prognostic estimating of the metallurgical coke quality dependence on the coking mixes composition, developed some time ago by authors of presented paper, was published in the Cokemaking International Vol. 13, 2/2001 (Czudek S. and al.: Simulation of Carbonization Process under Laboratory Conditions). The original procedure was newly accomplished by implementing a special method of the multi criteria evaluation of the definite coal components. New method is based on special processing of the technologic significant qualitative properties of the mined coal brands enabling deeply estimate the impacts of their application in metallurgical coke production. The importance of this evaluating system exceeds largely the well known method that is incorporated in the international coal classification. The main advantage of the new method is the fully respecting of the specialties marking the geographic different coalfields. (Abstract only)
A classification of substance-dependent men on temperament and severity variables.
Henderson, Melinda J; Galen, Luke W
2003-06-01
This study examined the validity of classifying substance abusers based on temperament and dependence severity, and expanded the scope of typology differences to proximal determinants of use (e.g., expectancies, motives). Patients were interviewed about substance use, depression, and family history of alcohol and drug abuse. Self-report instruments measuring temperament, expectancies, and motives were completed. Participants were 147 male veterans admitted to inpatient substance abuse treatment at a U.S. Department of Veterans Affairs medical center. Cluster analysis identified four types of users with two high substance problem severity and two low substance problem severity groups. Two, high problem severity, early onset groups differed only on the cluster variable of negative affectivity (NA), but showed differences on antisocial personality characteristics, hypochondriasis, and coping motives for alcohol. The two low problem severity groups were distinguished by age of onset and positive affectivity (PA). The late onset, low PA group had a higher incidence of depression, a greater tendency to use substances in solitary contexts, and lower enhancement motives for alcohol compared to the early onset, high PA cluster. The four-cluster solution yielded more distinctions on external criteria than the two-cluster solution. Such temperament variation within both high and low severity substance abusers may be important for treatment planning.
Khan Riaz
2011-08-01
Full Text Available Abstract Background Despite the importance of heavy drinking and alcohol dependence among patients with opiate and cocaine dependence, few studies have evaluated specific interventions within this group. The aim of the present study was to evaluate the impact of screening with the Alcohol Use Disorders Identification Test (AUDIT and of brief intervention (BI on alcohol use in a sample of patients treated for opioid or cocaine dependence in a specialized outpatient clinic. Methods Adult outpatients treated for opioid or cocaine dependence in Switzerland were screened for excessive alcohol drinking and dependence with the AUDIT. Patients with AUDIT scores that indicated excessive drinking or dependence were randomized into two groups--treatment as usual or treatment as usual together with BI--and assessed at 3 months and 9 months. Results Findings revealed a high rate (44% of problematic alcohol use (excessive drinking and dependence among patients with opiate and cocaine dependence. The number of drinks per week decreased significantly between T0 (inclusion and T3 (month 3. A decrease in average AUDIT scores was observed between T0 and T3 and between T0 and T9 (month 9. No statistically significant difference between treatment groups was observed. Conclusions In a substance abuse specialized setting, screening for alcohol use with the AUDIT, followed by feedback on the score, and use of alcohol BI are both possibly useful strategies to induce changes in problematic alcohol use. Definitive conclusions cannot, however, be drawn from the study because of limitations such as lack of a naturalistic group. An important result of the study is the excellent internal consistency of AUDIT in a population treated for opiate or cocaine dependence.
Radial dependence of line profile variability in seven O9--B0.5 stars
Martins, F; Hillier, D J; Donati, J -F; Bouret, J -C
2014-01-01
Massive stars show a variety of spectral variability: presence of discrete absorption components in UV P-Cygni profiles, optical line profile variability, X-ray variability, radial velocity modulations. Our goal is to study the spectral variability of single OB stars to better understand the relation between photospheric and wind variability. For that, we rely on high spectral resolution, high signal-to-noise ratio optical spectra collected with the spectrograph NARVAL on the Telescope Bernard Lyot at Pic du Midi. We investigate the variability of twelve spectral lines by means of the Temporal Variance Spectrum (TVS). The selected lines probe the radial structure of the atmosphere, from the photosphere to the outer wind. We also perform a spectroscopic analysis with atmosphere models to derive the stellar and wind properties, and to constrain the formation region of the selected lines. We show that variability is observed in the wind lines of all bright giants and supergiants, on a daily timescale. Lines form...
Alaskan soil carbon stocks: spatial variability and dependence on environmental factors
U. Mishra
2012-09-01
Full Text Available The direction and magnitude of soil organic carbon (SOC changes in response to climate change depend on the spatial and vertical distributions of SOC. We estimated spatially resolved SOC stocks from surface to C horizon, distinguishing active-layer and permafrost-layer stocks, based on geospatial analysis of 472 soil profiles and spatially referenced environmental variables for Alaska. Total Alaska state-wide SOC stock was estimated to be 77 Pg, with 61% in the active-layer, 27% in permafrost, and 12% in non-permafrost soils. Prediction accuracy was highest for the active-layer as demonstrated by highest ratio of performance to deviation (1.5. Large spatial variability was predicted, with whole-profile, active-layer, and permafrost-layer stocks ranging from 1–296 kg C m^{−2}, 2–166 kg m^{−2}, and 0–232 kg m^{−2}, respectively. Temperature and soil wetness were found to be primary controllers of whole-profile, active-layer, and permafrost-layer SOC stocks. Secondary controllers, in order of importance, were found to be land cover type, topographic attributes, and bedrock geology. The observed importance of soil wetness rather than precipitation on SOC stocks implies that the poor representation of high-latitude soil wetness in Earth system models may lead to large uncertainty in predicted SOC stocks under future climate change scenarios. Under strict caveats described in the text and assuming temperature changes from the A1B Intergovernmental Panel on Climate Change emissions scenario, our geospatial model indicates that the equilibrium average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss associated with this warming would be highest under continuous permafrost (31%, followed by discontinuous (28%, isolated (24.3%, and sporadic (23.6% permafrost areas. Our high-resolution mapping of soil carbon stock reveals the
Alaskan soil carbon stocks: spatial variability and dependence on environmental factors
U. Mishra
2012-05-01
Full Text Available The direction and magnitude of soil organic carbon (SOC changes in response to climate change depend on the spatial and vertical distributions of SOC. We estimated spatially-resolved SOC stocks from surface to C horizon, distinguishing active-layer and permafrost-layer stocks, based on geospatial analysis of 472 soil profiles and spatially referenced environmental variables for Alaska. Total Alaska state-wide SOC stock was estimated to be 77 Pg, with 61% in the active-layer, 27% in permafrost, and 12% in non-permafrost soils. Prediction accuracy was highest for the active-layer as demonstrated by highest ratio of performance to deviation (1.5. Large spatial variability was predicted, with whole-profile, active-layer, and permafrost-layer stocks ranging from 1–296 kg C m^{−2}, 2–166 kg m^{−2}, and 0–232 kg m^{−2}, respectively. Temperature and soil wetness were found to be primary controllers of whole-profile, active-layer, and permafrost-layer SOC stocks. Secondary controllers, in order of importance, were: land cover type, topographic attributes, and bedrock geology. The observed importance of soil wetness rather than precipitation on SOC stocks implies that the poor representation of high-latitude soil wetness in Earth System Models may lead to large uncertainty in predicted SOC stocks under future climate change scenarios. Under strict caveats described in the text and assuming temperature changes from the A1B Intergovernmental Panel on Climate Change emissions scenario, our geospatial model indicates that the equilibrium average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss associated with this warming would be highest under continuous permafrost (31%, followed by discontinuous (28%, isolated (24.3%, and sporadic (23.6% permafrost areas. Our high resolution mapping of soil carbon stock reveals the potential
Random recurrence equations and ruin in a Markov-dependent stochastic economic environment
Collamore, Jeffrey F.
2009-01-01
We develop sharp large deviation asymptotics for the probability of ruin in a Markov-dependent stochastic economic environment and study the extremes for some related Markovian processes which arise in financial and insurance mathematics, related to perpetuities and the ARCH(1) and GARCH(1,1) time...
Papusoi, C. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)], E-mail: cristian_papusoi@yahoo.com; Conraux, Y.; Prejbeanu, I.L. [Crocus Technology, 5 Robert Schumann, BP 1510, 38025 Grenoble (France); Sousa, R.; Dieny, B. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)
2009-08-15
The minimum applied field H{sub SW} required to reverse the magnetic moment of the ferromagnetic/antiferromagnetic storage layer of a thermally assisted magnetic random access memory (TA-MRAM) device during the application of a heating electric pulse is investigated as a function of pulse power P{sub HP} and duration {delta}. For the same power of the heating pulse P{sub HP} (or, equivalently, for the same temperature of the storage layer), H{sub SW} increases with decreasing heating time {delta}. This behavior is consistently interpreted by a thermally activated propagating domain-wall switching model, corroborated by a real-time study of switching. The increase of H{sub SW} with decreasing pulse width introduces a constraint for the minimum power consumption of a TA-MRAM where writing combines heating and magnetic field application.
Cohen, D; Kottos, T
2001-03-01
We study a classically chaotic system that is described by a Hamiltonian H(Q,P;x), where (Q,P) are the canonical coordinates of a particle in a two-dimensional well, and x is a parameter. By changing x we can deform the "shape" of the well. The quantum eigenstates of the system are /n(x)>. We analyze numerically how the parametric kernel P(n/m)=//(2) evolves as a function of delta(x)[triple bond](x-x(0)). This kernel, regarded as a function of n-m, characterizes the shape of the wave functions, and it also can be interpreted as the local density of states. The kernel P(n/m) has a well-defined classical limit, and the study addresses the issue of quantum-classical correspondence. Both the perturbative and the nonperturbative regimes are explored. The limitations of the random matrix theory approach are demonstrated.
Ahmet Kuzu
2014-01-01
Full Text Available This paper proposes two novel master-slave configurations that provide improvements in both control and communication aspects of teleoperation systems to achieve an overall improved performance in position control. The proposed novel master-slave configurations integrate modular control and communication approaches, consisting of a delay regulator to address problems related to variable network delay common to such systems, and a model tracking control that runs on the slave side for the compensation of uncertainties and model mismatch on the slave side. One of the configurations uses a sliding mode observer and the other one uses a modified Smith predictor scheme on the master side to ensure position transparency between the master and slave, while reference tracking of the slave is ensured by a proportional-differentiator type controller in both configurations. Experiments conducted for the networked position control of a single-link arm under system uncertainties and randomly varying network delays demonstrate significant performance improvements with both configurations over the past literature.
Joshi Meesha
2010-03-01
Full Text Available Abstract Background An earlier study showed that a week of yoga practice was useful in stress management after a natural calamity. Due to heavy rain and a rift on the banks of the Kosi river, in the state of Bihar in north India, there were floods with loss of life and property. A week of yoga practice was given to the survivors a month after the event and the effect was assessed. Methods Twenty-two volunteers (group average age ± S.D, 31.5 ± 7.5 years; all of them were males were randomly assigned to two groups, yoga and a non-yoga wait-list control group. The yoga group practiced yoga for an hour daily while the control group continued with their routine activities. Both groups' heart rate variability, breath rate, and four symptoms of emotional distress using visual analog scales, were assessed on the first and eighth day of the program. Results There was a significant decrease in sadness in the yoga group (p Conclusions A week of yoga can reduce feelings of sadness and possibly prevent an increase in anxiety in flood survivors a month after the calamity. Trial Registration Clinical Trials Registry of India: CTRI/2009/091/000285
Wang, Kezhi
2015-06-01
Exact results for the probability density function (PDF) and cumulative distribution function (CDF) of the sum of ratios of products (SRP) and the sum of products (SP) of independent α-μ random variables (RVs) are derived. They are in the form of 1-D integral based on the existing works on the products and ratios of α-μ RVs. In the derivation, generalized Gamma (GG) ratio approximation (GGRA) is proposed to approximate SRP. Gamma ratio approximation (GRA) is proposed to approximate SRP and the ratio of sums of products (RSP). GG approximation (GGA) and Gamma approximation (GA) are used to approximate SP. The proposed results of the SRP can be used to calculate the outage probability (OP) for wireless multihop relaying systems or multiple scattering channels with interference. The proposed results of the SP can be used to calculate the OP for these systems without interference. In addition, the proposed approximate result of the RSP can be used to calculate the OP of the signal-To-interference ratio (SIR) in a multiple scattering system with interference. © 1967-2012 IEEE.
Precise Asymptotics for Random Matrices and Random Growth Models
Zhong Gen SU
2008-01-01
The author considers the largest eigenvalues of random matrices from Gaussian unitary ensemble and Laguerre unitary ensemble, and the rightmost charge in certain random growth models.We obtain some precise asymptotics results, which are in a sense similar to the precise asymptotics for sums of independent random variables in the context of the law of large numbers and complete convergence. Our proofs depend heavily upon the upper and lower tail estimates for random matrices and random growth models. The Tracy-Widom distribution plays a central role as well.
Hul, Oleh; Seba, Petr; Sirko, Leszek
2009-06-01
Parameter-dependent statistical properties of spectra of totally connected irregular quantum graphs with Neumann boundary conditions are studied. The autocorrelation functions of level velocities c(x) and c[over ](omega,x) as well as the distributions of level curvatures and avoided crossing gaps are calculated. The numerical results are compared with the predictions of random matrix theory for Gaussian orthogonal ensemble (GOE) and for coupled GOE matrices. The application of coupled GOE matrices was justified by studying localization phenomena in graphs' wave functions Psi(x) using the inverse participation ratio and the amplitude distribution P(Psi(x)) .
Method of frequency dependent correlations: investigating the variability of total solar irradiance
Pelt, J.; Käpylä, M. J.; Olspert, N.
2017-03-01
Context. This paper contributes to the field of modeling and hindcasting of the total solar irradiance (TSI) based on different proxy data that extend further back in time than the TSI that is measured from satellites. Aims: We introduce a simple method to analyze persistent frequency-dependent correlations (FDCs) between the time series and use these correlations to hindcast missing historical TSI values. We try to avoid arbitrary choices of the free parameters of the model by computing them using an optimization procedure. The method can be regarded as a general tool for pairs of data sets, where correlating and anticorrelating components can be separated into non-overlapping regions in frequency domain. Methods: Our method is based on low-pass and band-pass filtering with a Gaussian transfer function combined with de-trending and computation of envelope curves. Results: We find a major controversy between the historical proxies and satellite-measured targets: a large variance is detected between the low-frequency parts of targets, while the low-frequency proxy behavior of different measurement series is consistent with high precision. We also show that even though the rotational signal is not strongly manifested in the targets and proxies, it becomes clearly visible in FDC spectrum. A significant part of the variability can be explained by a very simple model consisting of two components: the original proxy describing blanketing by sunspots, and the low-pass-filtered curve describing the overall activity level. The models with the full library of the different building blocks can be applied to hindcasting with a high level of confidence, Rc ≈ 0.90. The usefulness of these models is limited by the major target controversy. Conclusions: The application of the new method to solar data allows us to obtain important insights into the different TSI modeling procedures and their capabilities for hindcasting based on the directly observed time intervals.
Lippman, Thomas; Moler, Kathryn A.
2012-07-20
Microscopic variations in composition or structure can lead to nanoscale inhomogeneity in superconducting properties such as the magnetic penetration depth, but measurements of these properties are usually made on longer length scales. We solve a generalized London equation with a non-uniform penetration depth {lambda}(r), obtaining an approximate solution for the disorder-averaged Meissner screening. We find that the effective penetration depth is different from the average penetration depth and is sensitive to the details of the disorder. These results indicate the need for caution when interpreting measurements of the penetration depth and its temperature dependence in systems which may be inhomogeneous.
负相伴随机变量的非经典重对数律%A NONCLASSICAL LAW OF ITERATED LOGARITHM FOR NEGATIVELY ASSOCIATED RANDOM VARIABLES
蒋烨
2003-01-01
A nonclassical law of iterated logarithm that holds for a stationary negativelyassociated sequence of random variables with finite variance is proved in this paperThe proof isbased on a Rosenthal type maximal inequality and the subsequence metlodThis result extendsthe work of Klesov,Rosalsky (2001) and Shao,Su (1999).
The derivative-dependent functional variable separation for the evolution equations
Zhang Shun-Li; Lou Sen-Yue; Qu Chang-Zheng
2006-01-01
This paper studies variable separation of the evolution equations via the generalized conditional symmetry. To illustrate, we classify the extended nonlinear wave equation utt = A(u,ux)uxx+B(u,ux,ut) which admits the derivativedependent functional separable solutions (DDFSSs). We also extend the concept of the DDFSS to cover other variable separation approaches.
Bernstein, Steven L.; D’Onofrio, Gail; Rosner, June; O’Malley, Stephanie; Makuch, Robert; Busch, Susan; Pantalon, Michael V.; Toll, Benjamin
2016-01-01
Background Tobacco use is common among ED patients, many of whom are low-income. Our objective was to study the efficacy of an intervention incorporating motivational interviewing, nicotine replacement, and quitline referral for adult smokers in an ED. Methods A two-arm randomized clinical trial conducted from October 2010–December 2012, at a 90,000 visit/year urban ED in the northeastern U.S. Eligible subjects were age 18 years or older who smoked and were self-pay or had Medicaid insurance. Intervention subjects received a motivational interview by a trained research assistant, 6 weeks of nicotine patches and gum initiated in the ED, a faxed referral to the state smokers’ quitline, a booster call, and a brochure. Control subjects received the brochure, which provided quitline information. The primary outcome was biochemically confirmed tobacco abstinence at three months. Secondary endpoints included quitline utilization. Results Of 778 enrolled subjects, 774 (99.5%) were alive at three months. The prevalence of biochemically confirmed abstinence was 12.2% (47/386) in the intervention arm vs. 4.9% (19/388) in the control arm, for a difference in quit rates of 7.3% (95% CI 3.2%, 11.5%). In multivariable logistic modeling controlling for age, sex, and race/ethnicity, study subjects remained more likely to be abstinent than controls (OR 2.72, 95% CI 1.55, 4.75). Conclusions An intensive intervention improved tobacco abstinence rates in low-income ED smokers. Because approximately 20 million smokers, many of whom are low-income, visit US EDs annually, these results suggest ED-initiated treatment may be an effective technique to treat this group of smokers. PMID:25920384
A Strong Logarithmic Law for Arrays of Random Variables%随机变量阵列的一个强大数律
邵杰
2014-01-01
Law of large numbers for sequences of random variables plays an important role in the limit proba -bility theory and mathematical statistics .Classic law of large numbers was mainly about independent and identically distributed random variable sequences .Many scholars are devoted to weaken the condition of independence and i-dentical distribution and extend the sequence of random variables to array of random variables .In this study , the author obtains a strong law for arrays of random variables by using the conclusion of Borel -Cantelli lemma and martingale difference sequence .Furthermore, as a special case , a strong law for the sequence of weighted sums is accordingly gotten .%随机变量序列的大数定律在概率极限理论和数理统计中扮演着重要的角色，经典的大数律主要是研究独立同分布的随机变量序列，后来许多学者致力于减弱独立同分布这一条件，或将随机变量序列推广到随机变量阵列。文章主要研究任意随机变量阵列的强大数律，利用Borel-Cantelli引理和鞅差序列的结论，通过推理论证，得到了任意随机变量阵列的一个强大数律，并且作为特例，得到了随机变量序列加权和的强大数律。
A Strong Limit Theorem on Generalized Random Selection for m-valued Random Sequences
WANGZhong-zhi; XUFu-xia
2003-01-01
In this paper, a strong limit theorem on gambling strategy for binary Bernoulli sequence, i.e.irregularity theorem, is extended to random selection for dependent m-valued random variables, via using a new method-differentiability on net. Furthermore, by allowing the selection function to take value in finite interval [-M, M], the conception of random selection is generalized.
Ahmadi-Abhari Seyed Ali
2003-11-01
Full Text Available Abstract Background Results of preclinical studies suggest that the GABAB receptor agonist baclofen may be useful in treatment of opioid dependence. This study was aimed at assessing the possible efficacy of baclofen for maintenance treatment of opioid dependence. Methods A total of 40 opioid-dependent patients were detoxified and randomly assigned to receive baclofen (60 mg/day or placebo in a 12-week, double blind, parallel-group trial. Primary outcome measure was retention in treatment. Secondary outcome measures included opioids and alcohol use according to urinalysis and self-report ratings, intensity of opioid craving assessed with a visual analogue scale, opioid withdrawal symptoms as measured by the Short Opiate Withdrawal Scale and depression scores on the Hamilton inventory. Results Treatment retention was significantly higher in the baclofen group. Baclofen also showed a significant superiority over placebo in terms of opiate withdrawal syndrome and depressive symptoms. Non-significant, but generally favorable responses were seen in the baclofen group with other outcome measures including intensity of opioid craving and self-reported opioid and alcohol use. However, no significant difference was seen in the rates of opioid-positive urine tests. Additionally, the drug side effects of the two groups were not significantly different. Conclusion The results support further study of baclofen in the maintenance treatment of opioid dependence.
Bhargava, Kapilesh, E-mail: kapilesh_66@yahoo.co.u [Architecture and Civil Engineering Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India); Mori, Yasuhiro [Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8603 (Japan); Ghosh, A.K. [Reactor Safety Division, Bhabha Atomic Research Center, Trombay, Mumbai 400 085 (India)
2011-05-15
Research highlights: Predictive models for corrosion-induced damages in RC structures. Formulations for time-dependent flexural and shear strengths of corroded RC beams. Methodology for mean and c.o.v. for time-dependent strengths of corroded RC beams. Simple estimation of mean and c.o.v. for flexural strength with loss of bond. - Abstract: The structural deterioration of reinforced concrete (RC) structures due to reinforcement corrosion is a major worldwide problem. Damages to RC structures due to reinforcement corrosion manifest in the form of expansion, cracking and eventual spalling of the cover concrete; thereby resulting in serviceability and durability degradation of such structures. In addition to loss of cover, RC structure may suffer structural damages due to loss of reinforcement cross-sectional area, and loss of bond between corroded reinforcement and surrounding cracked concrete, sometimes to the extent that the structural failure becomes inevitable. This paper forms the first part of a study which addresses time-dependent reliability analyses of RC beams affected by reinforcement corrosion. In this paper initially the predictive models are presented for the quantitative assessment of time-dependent damages in RC beams, recognized as loss of mass and cross-sectional area of reinforcing bar, loss of concrete section owing to the peeling of cover concrete, and loss of bond between corroded reinforcement and surrounding cracked concrete. Then these models have been used to present analytical formulations for evaluating time-dependent flexural and shear strengths of corroded RC beams, based on the standard composite mechanics expressions for RC sections. Further by considering variability in the identified basic variables that could affect the time-dependent strengths of corrosion-affected RC beams, the estimation of statistical descriptions for the time-dependent strengths is presented for a typical simply supported RC beam. The statistical descriptions
Gallovič, F.
2016-11-01
Strong ground motion simulations require physically plausible earthquake source model. Here, I present the application of such a kinematic model introduced originally by Ruiz et al. (Geophys J Int 186:226-244, 2011). The model is constructed to inherently provide synthetics with the desired omega-squared spectral decay in the full frequency range. The source is composed of randomly distributed overlapping subsources with fractal number-size distribution. The position of the subsources can be constrained by prior knowledge of major asperities (stemming, e.g., from slip inversions), or can be completely random. From earthquake physics point of view, the model includes positive correlation between slip and rise time as found in dynamic source simulations. Rupture velocity and rise time follows local S-wave velocity profile, so that the rupture slows down and rise times increase close to the surface, avoiding unrealistically strong ground motions. Rupture velocity can also have random variations, which result in irregular rupture front while satisfying the causality principle. This advanced kinematic broadband source model is freely available and can be easily incorporated into any numerical wave propagation code, as the source is described by spatially distributed slip rate functions, not requiring any stochastic Green's functions. The source model has been previously validated against the observed data due to the very shallow unilateral 2014 Mw6 South Napa, California, earthquake; the model reproduces well the observed data including the near-fault directivity (Seism Res Lett 87:2-14, 2016). The performance of the source model is shown here on the scenario simulations for the same event. In particular, synthetics are compared with existing ground motion prediction equations (GMPEs), emphasizing the azimuthal dependence of the between-event ground motion variability. I propose a simple model reproducing the azimuthal variations of the between-event ground motion
Ruediger Schellenberg
2012-01-01
Full Text Available Extracts from Cimicifuga racemosa (CR, synonym Actaea racemosa have shown efficacy in trials in women with menopausal symptoms. Yet, dose dependency remains unclear. Therefore, 180 female outpatients with climacteric complaints were treated for 12 weeks in a randomized, double-blind, placebo-controlled, 3-armed trial (CR extract Ze 450 in 6.5 mg or 13.0 mg, or placebo. Primary outcome was the difference in menopausal symptoms (vasomotor, psychological, and somatic, assessed by the Kupperman Menopausal Index between baseline and week 12. Secondary efficacy variables were patients’ self-assessments of general quality of life (QoL, responder rates, and safety. Compared to placebo, patients receiving Ze 450 showed a significant reduction in the severity of menopausal symptoms in a dose-dependent manner from baseline to endpoint (mean absolute differences 17.0 (95% CI 14.65–19.35 score points, P<0.0001 for 13.0 mg; mean absolute differences 8.47 (95% CI 5.55–11.39 score points, P=0.0003 for 6.5 mg. QoL and responder rates corresponded with the main endpoint. Changes in menopausal symptoms and QoL were inversely correlated. Reported adverse events and clinical laboratory testing did not raise safety concerns. The CR extract Ze 450 is an effective and well-tolerated nonhormonal alternative to hormone treatment for symptom relief in menopausal women.
Goudarzi, Nasser; Shahsavani, Davood; Emadi-Gandaghi, Fereshteh; Chamjangali, Mansour Arab
2016-10-01
In this work, a noble quantitative structure-property relationship technique is proposed on the basis of the random forest for prediction of the retention indices of some sulfur organic compounds. In order to calculate the retention indices of these compounds, the theoretical descriptors produced using their molecular structures are employed. The influence of the significant parameters affecting the capability of the developed random forest prediction power such as the number of randomly selected variables applied to split each node (m) and the number of trees (nt ) is studied to obtain the best model. After optimizing the nt and m parameters, the random forest model conducted for m = 70 and nt = 460 was found to yield the best results. The artificial neural network and multiple linear regression modeling techniques are also used to predict the retention index values for these compounds for comparison with the results of random forest model. The descriptors selected by the stepwise regression and random forest model are used to build the artificial neural network models. The results achieved showed the superiority of the random forest model over the other models for prediction of the retention indices of the studied compounds.
Delgado Saa, Jaime F.; de Pesters, Adriana; Cetin, Mujdat
2016-06-01
Objective. In this work we propose the use of conditional random fields with long-range dependencies for the classification of finger movements from electrocorticographic recordings. Approach. The proposed method uses long-range dependencies taking into consideration time-lags between the brain activity and the execution of the motor task. In addition, the proposed method models the dynamics of the task executed by the subject and uses information about these dynamics as prior information during the classification stage. Main results. The results show that incorporating temporal information about the executed task as well as incorporating long-range dependencies between the brain signals and the labels effectively increases the system’s classification performance compared to methods in the state of art. Significance. The method proposed in this work makes use of probabilistic graphical models to incorporate temporal information in the classification of finger movements from electrocorticographic recordings. The proposed method highlights the importance of including prior information about the task that the subjects execute. As the results show, the combination of these two features effectively produce a significant improvement of the system’s classification performance.
Takeru Honda
2011-07-01
Full Text Available Information processing of the cerebellar granular layer composed of granule and Golgi cells is regarded as an important first step toward the cerebellar computation. Our previous theoretical studies have shown that granule cells can exhibit random alternation between burst and silent modes, which provides a basis of population representation of the passage-of-time (POT from the onset of external input stimuli. On the other hand, another computational study has reported that granule cells can exhibit synchronized oscillation of activity, as consistent with observed oscillation in local field potential recorded from the granular layer while animals keep still. Here we have a question of whether an identical network model can explain these distinct dynamics. In the present study, we carried out computer simulations based on a spiking network model of the granular layer varying two parameters: the strength of a current injected to granule cells and the concentration of Mg²⁺ which controls the conductance of NMDA channels assumed on the Golgi cell dendrites. The simulations showed that cells in the granular layer can switch activity states between synchronized oscillation and random burst-silent alternation depending on the two parameters. For higher Mg²⁺ concentration and a weaker injected current, granule and Golgi cells elicited spikes synchronously (synchronized oscillation state. In contrast, for lower Mg²⁺ concentration and a stronger injected current, those cells showed the random burst-silent alternation (POT-representing state. It is suggested that NMDA channels on the Golgi cell dendrites play an important role for determining how the granular layer works in response to external input.
Patterns of variability in early-life traits of fishes depend on spatial scale of analysis.
Di Franco, Antonio; Guidetti, Paolo
2011-06-23
Estimates of early-life traits of fishes (e.g. pelagic larval duration (PLD) and spawning date) are essential for investigating and assessing patterns of population connectivity. Such estimates are available for a large number of both tropical and temperate fish species, but few studies have assessed their variability in space, especially across multiple scales. The present study, where a Mediterranean fish (i.e. the white seabream Diplodus sargus sargus) was used as a model, shows that spawning date and PLD are spatially more variable at a scale of kilometres than at a scale of tens to hundreds of kilometres. This study indicates the importance of considering spatial variability of early-life traits of fishes in order to properly delineate connectivity patterns at larval stages (e.g. by means of Lagrangian simulations), thus providing strategically useful information on connectivity and relevant management goals (e.g. the creation of networks of marine reserves).
Chang Dennis
2011-07-01
Full Text Available Abstract Background Chronic work-related stress is a significant and independent risk factor for cardiovascular and metabolic diseases and associated mortality, particularly when compounded by a sedentary work environment. Heart rate variability (HRV provides an estimate of parasympathetic and sympathetic autonomic control, and can serve as a marker of physiological stress. Hatha yoga is a physically demanding practice that can help to reduce stress; however, time constraints incurred by work and family life may limit participation. The purpose of the present study is to determine if a 10-week, worksite-based yoga program delivered during lunch hour can improve resting HRV and related physical and psychological parameters in sedentary office workers. Methods and design This is a parallel-arm RCT that will compare the outcomes of participants assigned to the experimental treatment group (yoga to those assigned to a no-treatment control group. Participants randomized to the experimental condition will engage in a 10-week yoga program delivered at their place of work. The yoga sessions will be group-based, prescribed three times per week during lunch hour, and will be led by an experienced yoga instructor. The program will involve teaching beginner students safely and progressively over 10 weeks a yoga sequence that incorporates asanas (poses and postures, vinyasa (exercises, pranayama (breathing control and meditation. The primary outcome of this study is the high frequency (HF spectral power component of HRV (measured in absolute units; i.e. ms2, a measure of parasympathetic autonomic control. Secondary outcomes include additional frequency and time domains of HRV, and measures of physical functioning and psychological health status. Measures will be collected prior to and following the intervention period, and at 6 months follow-up to determine the effect of intervention withdrawal. Discussion This study will determine the effect of worksite
Age Dependent Variability in Gene Expression in Fischer 344 Rat Retina.
Recent evidence suggests older adults may be a sensitive population with regard to environmental exposure to toxic compounds. One source of this sensitivity could be an enhanced variability in response. Studies on phenotypic differences have suggested that variation in response d...
Bedford, T.; Meilijson, I.
1997-01-01
It is well known that the joint distribution of a pair of lifetime variables $X_1$ and $X_2$ which right censor each other cannot be specified in terms of the subsurvival functions $$P(X_2 > X_1 > x), \\quad P(X_1 > X_2 > x)$ \\quad \\text{and} \\quad $P(X_1 = X_2 > x)$$ without additional assumptions s
Jaring, M; Bosch, J; Ehrich, HD; Schewe, KD
2004-01-01
In a software product family context, software architects design architectures that support product diversification in both space (multiple contexts) and time (changing contexts). Product diversification is based on the concept of variability: a single architecture and a set of components support a
Connection Between Essential Supremum (Infimum) and Norms for a Random Variable%随机变量本性上(下)确界与范数的关系
肖立顺; 范胜君; 徐娜
2012-01-01
给出了随机变量本性上(下)确界的2种新定义,并根据一般确界定义和概率的性质对2种新定义的等价性进行了证明；进而研究了随机变量本性上(下)确界与随机变量p范数,无穷范数之间的关系和相互表示问题.%Two new definitions of the essential supremum (infimum) of a random variable are introduced. And their equivalence is proved by use of supremum (infimum) and the properties of probability. Then the connection and representation among the essential supremum (infimum) , p-norm and infinite norm of a random variable are studied.
Kardaras, Constantinos
2012-01-01
We introduce the concepts of max-closedness and outer support points of convex sets in the nonnegative orthant of the topological vector space of all random variables built over a probability space, equipped with a topology consistent with convergence of sequences in probability. Max-closedness asks that maximal elements of the closure of a set already lie on the set. We show that outer support points arise naturally as optimizers of concave monotone maximization problems. It is further shown that the set of outer support points of a convex, max-closed and bounded set of nonnegative random variables is dense in the set of its maximal elements, which can be regarded as a version of the celebrated Bishop-Phelps theorem in a space that even fails to be locally convex.
Belendez, A; Gimeno, E; Mendez, D I; Alvarez, M L [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E [Departamento de Optica, FarmacologIa y AnatomIa, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es
2008-06-15
A modified generalized, rational harmonic balance method is used to construct approximate frequency-amplitude relations for a conservative nonlinear singular oscillator in which the restoring force is inversely proportional to the dependent variable. The procedure is used to solve the nonlinear differential equation approximately. The approximate frequency obtained using this procedure is more accurate than those obtained using other approximate methods and the discrepancy between the approximate frequency and the exact one is lower than 0.40%.
Contact-dependent performance variability of monolayer MoS{sub 2} field-effect transistors
Han, Gyuchull; Yoon, Youngki, E-mail: youngki.yoon@uwaterloo.ca [Department of Electrical and Computer Engineering and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)
2014-11-24
Using self-consistent quantum transport simulations, we investigate the performance variability of monolayer molybdenum disulfide (MoS{sub 2}) field-effect transistors (FETs) with various contact properties. Varying the Schottky barrier in MoS{sub 2} FETs affects the output characteristics more significantly than the transfer characteristics. If doped contacts are realized, the performance variation due to non-ideal contacts becomes negligible; otherwise, channel doping can effectively suppress the performance variability in metal-contact devices. Our scaling study also reveals that for sub-10-nm channels, doped-contact devices can be more robust in terms of switching, while metal-contact MoS{sub 2} FETs can undergo the smaller penalty in output conductance.
无
2000-01-01
Under very weak condition 0＜r(t)↑∞, t→∞, we obtain a series of equivalent conditions of complete convergence for maxima of m-dimensional products of iid random variables, which provide a useful tool for researching this class of questions. Some results on strong law of large numbers are given such that our results are much stronger than the corresponding result of Gadidov's.
王岳宝; 苏淳; 梁汉营; 成凤旸
2000-01-01
Under very weak condition 0 < r(t)↑∞ , t→∞. we obtain a series of equivalent conditions of complete convergence for maxima of m-dimensional products of iid random variables, which provide a useful tool for researching this class of questions. Some results on strong law of large numbers are given such that our results are much stronger than the corresponding result of Gadidov’s.
Near-infrared thermal emission from near-Earth asteroids: Aspect-dependent variability
Moskovitz, Nicholas A; DeMeo, Francesca E; Binzel, Richard P; Endicott, Thomas; Yang, Bin; Howell, Ellen S; Vervack, Ronald J; Fernandez, Yanga R
2016-01-01
Here we explore a technique for constraining physical properties of near-Earth asteroids (NEAs) based on variability in thermal emission as a function of viewing aspect. We present case studies of the low albedo, near-Earth asteroids (285263) 1998 QE2 and (175706) 1996 FG3. The Near-Earth Asteroid Thermal Model (NEATM) is used to fit signatures of thermal emission in near-infrared (0.8 - 2.5 micron) spectral data. This analysis represents a systematic study of thermal variability in the near-IR as a function of phase angle. The observations of QE2 imply that carefully timed observations from multiple viewing geometries can be used to constrain physical properties like retrograde versus prograde pole orientation and thermal inertia. The FG3 results are more ambiguous with detected thermal variability possibly due to systematic issues with NEATM, an unexpected prograde rotation state, or a surface that is spectrally and thermally heterogenous. This study highlights the potential diagnostic importance of high ph...
Hanel, R.; Thurner, S.; Tsallis, C.
2009-11-01
Extremization of the Boltzmann-Gibbs (BG) entropy S_{BG}=-kint dx p(x) ln p(x) under appropriate norm and width constraints yields the Gaussian distribution pG(x) ∝e-βx. Also, the basic solutions of the standard Fokker-Planck (FP) equation (related to the Langevin equation with additive noise), as well as the Central Limit Theorem attractors, are Gaussians. The simplest stochastic model with such features is N ↦∞ independent binary random variables, as first proved by de Moivre and Laplace. What happens for strongly correlated random variables? Such correlations are often present in physical situations as e.g. systems with long range interactions or memory. Frequently q-Gaussians, pq(x) ∝[1-(1-q)βx2]1/(1-q) [p1(x)=pG(x)] become observed. This is typically so if the Langevin equation includes multiplicative noise, or the FP equation to be nonlinear. Scale-invariance, e.g. exchangeable binary stochastic processes, allow a systematical analysis of the relation between correlations and non-Gaussian distributions. In particular, a generalized stochastic model yielding q-Gaussians for all (q ≠ 1) was missing. This is achieved here by using the Laplace-de Finetti representation theorem, which embodies strict scale-invariance of interchangeable random variables. We demonstrate that strict scale invariance together with q-Gaussianity mandates the associated extensive entropy to be BG.
Nam, Sungsik
2014-08-01
The joint statistics of partial sums of ordered random variables (RVs) are often needed for the accurate performance characterization of a wide variety of wireless communication systems. A unified analytical framework to determine the joint statistics of partial sums of ordered independent and identically distributed (i.i.d.) random variables was recently presented. However, the identical distribution assumption may not be valid in several real-world applications. With this motivation in mind, we consider in this paper the more general case in which the random variables are independent but not necessarily identically distributed (i.n.d.). More specifically, we extend the previous analysis and introduce a new more general unified analytical framework to determine the joint statistics of partial sums of ordered i.n.d. RVs. Our mathematical formalism is illustrated with an application on the exact performance analysis of the capture probability of generalized selection combining (GSC)-based RAKE receivers operating over frequency-selective fading channels with a non-uniform power delay profile. © 1991-2012 IEEE.
Jonna C Sandberg
Full Text Available Whole grain has shown potential to prevent obesity, cardiovascular disease and type 2 diabetes. Possible mechanism could be related to colonic fermentation of specific indigestible carbohydrates, i.e. dietary fiber (DF. The aim of this study was to investigate effects on cardiometabolic risk factors and appetite regulation the next day when ingesting rye kernel bread rich in DF as an evening meal.Whole grain rye kernel test bread (RKB or a white wheat flour based bread (reference product, WWB was provided as late evening meals to healthy young adults in a randomized cross-over design. The test products RKB and WWB were provided in two priming settings: as a single evening meal or as three consecutive evening meals prior to the experimental days. Test variables were measured in the morning, 10.5-13.5 hours after ingestion of RKB or WWB. The postprandial phase was analyzed for measures of glucose metabolism, inflammatory markers, appetite regulating hormones and short chain fatty acids (SCFA in blood, hydrogen excretion in breath and subjective appetite ratings.With the exception of serum CRP, no significant differences in test variables were observed depending on length of priming (P>0.05. The RKB evening meal increased plasma concentrations of PYY (0-120 min, P<0.001, GLP-1 (0-90 min, P<0.05 and fasting SCFA (acetate and butyrate, P<0.05, propionate, P = 0.05, compared to WWB. Moreover, RKB decreased blood glucose (0-120 min, P = 0.001, serum insulin response (0-120 min, P<0.05 and fasting FFA concentrations (P<0.05. Additionally, RKB improved subjective appetite ratings during the whole experimental period (P<0.05, and increased breath hydrogen excretion (P<0.001, indicating increased colonic fermentation activity.The results indicate that RKB evening meal has an anti-diabetic potential and that the increased release of satiety hormones and improvements of appetite sensation could be beneficial in preventing obesity. These effects could
Ram Paras
2016-01-01
Full Text Available An attempt has been made to describe the effects of geothermal viscosity with viscous dissipation on the three dimensional time dependent boundary layer flow of magnetic nanofluids due to a stretchable rotating plate in the presence of a porous medium. The modelled governing time dependent equations are transformed a from boundary value problem to an initial value problem, and thereafter solved by a fourth order Runge-Kutta method in MATLAB with a shooting technique for the initial guess. The influences of mixed temperature, depth dependent viscosity, and the rotation strength parameter on the flow field and temperature field generated on the plate surface are investigated. The derived results show direct impact in the problems of heat transfer in high speed computer disks (Herrero et al. [1] and turbine rotor systems (Owen and Rogers [2].
Sozcu, Omer Faruk
2014-01-01
This study examines the relationships between cognitive styles of field dependent learners with their attitudes towards e-learning (distance education) and instructional behavior in e-learning instruction. The Group Embedded Figures Test (GEFT) and the attitude survey (for students' preferences) towards e-learning instruction as distance education…
Near-infrared thermal emission from near-Earth asteroids: Aspect-dependent variability
Moskovitz, Nicholas A.; Polishook, David; DeMeo, Francesca E.; Binzel, Richard P.; Endicott, Thomas; Yang, Bin; Howell, Ellen S.; Vervack, , Ronald J.; Fernández, Yanga R.
2017-03-01
Here we explore a technique for constraining physical properties of near-Earth asteroids (NEAs) based on variability in thermal emission as a function of viewing aspect. We present case studies of the low albedo, near-Earth asteroids (285263) 1998 QE2 and (175706) 1996 FG3. The Near-Earth Asteroid Thermal Model (NEATM) is used to fit signatures of thermal emission in near-infrared (0.8 - 2.5 μm) spectral data. This analysis represents a systematic study of thermal variability in the near-IR as a function of phase angle. The observations of QE2 imply that carefully timed observations from multiple viewing geometries can be used to constrain physical properties like retrograde versus prograde pole orientation and thermal inertia. The FG3 results are more ambiguous with detected thermal variability possibly due to systematic issues with NEATM, an unexpected prograde rotation state, or a surface that is spectrally and thermally heterogenous. This study highlights the potential diagnostic importance of high phase angle thermal measurements on both sides of opposition. We find that the NEATM thermal beaming parameters derived from our near-IR data tend to be of order10's of percent higher than parameters from ensemble analyses of longer wavelength data sets. However, a systematic comparison of NEATM applied to data in different wavelength regimes is needed to understand whether this offset is simply a reflection of small number statistics or an intrinsic limitation of NEATM when applied to near-IR data. With the small sample presented here, it remains unclear whether NEATM modeling at near-IR wavelengths can robustly determine physical properties like pole orientation and thermal inertia.
Mason, Barbara J.; Crean, Rebecca; Goodell, Vivian; Light, John M.; Quello, Susan; Shadan, Farhad; Buffkins, Kimberly; Kyle, Mark; Adusumalli, Murali; Begovic, Adnan; Rao, Santosh
2012-01-01
There are no FDA-approved pharmacotherapies for cannabis dependence. Cannabis is the most widely used illicit drug in the world, and patients seeking treatment for primary cannabis dependence represent 25% of all substance use admissions. We conducted a phase IIa proof-of-concept pilot study to examine the safety and efficacy of a calcium channel/GABA modulating drug, gabapentin, for the treatment of cannabis dependence. A 12-week, randomized, double-blind, placebo-controlled clinical trial w...
Ryan, Kenny J.; Oglesby, David D.
2017-03-01
The development of the rate- and state-dependent friction framework (Dieterich Appl Geophys 116:790-806, 1978; J Geophys Res 84, 2161-2168, 1979; Ruina Friction laws and instabilities: a quasistatic analysis of some dry friction behavior, Ph.D. Thesis, Brown Univ., Providence, R.I., 1980; J Geophys Res 88:10359-10370, 1983) includes the dependence of friction coefficient on normal stress (Linker and Dieterich J Geophys Res 97:4923-4940, 1992); however, a direct dependence of the friction law on time-varying normal stress in dynamic stepover and dip-slip fault models has not yet been extensively explored. Using rate- and state-dependent friction laws and a 2-D dynamic finite element code (Barall J Int 178, 845-859, 2009), we investigate the effect of the Linker-Dieterich dependence of state variable on normal stress at stepovers and dip-slip faults, where normal stress should not be constant with time (e.g., Harris and Day J Geophys Res 98:4461-4472, 1993; Nielsen Geophys Res Lett 25:125-128, 1998). Specifically, we use the relation d ψ/d t = -( α/ σ)(d σ/d t) from Linker and Dieterich (J Geophys Res 97:4923-4940, 1992), in which a change in normal stress leads to a change in state variable of the opposite sign. We investigate a range of values for alpha, which scales the impact of the normal stress change on state, from 0 to 0.5 (laboratory values range from 0.2 to 0.56). For stepovers, we find that adding normal-stress dependence to the state variable delays or stops re-nucleation on the secondary fault segment when compared to normal-stress-independent state evolution. This inhibition of jumping rupture is due to the fact that re-nucleation along the secondary segment occurs in areas of decreased normal stress in both compressional and dilational stepovers. However, the magnitude of such an effect differs between dilational and compressional systems. Additionally, it is well known that the asymmetric geometry of reverse and normal faults can lead to greater
Pisano, M V; Ferreras, S; Krapacher, F A; Paglini, G; Arias, C
2012-07-15
The capability to acquire context conditioning does not emerge until weaning, at least when the defining features of the context lack explicit and salient olfactory cues. Contextual learning deficits in preweanling rats have been associated with functional immaturity of the dorsal hippocampus. According to recent studies, the so-called context preexposure facilitation effect (CPFE) - a hippocampus-dependent effect - is not observed until postnatal day 23 (PD23). In these studies the footshock intensity employed was higher (1.5 mA) than in adult studies, and context conditioning was inferred from a single behavioral measure (percentage of freezing). The present study examined the CPFE on PD17 and PD23 by analyzing multiple dependent variables, including fecal boli and an ethogram covering the complete behavioral repertoire of the rat. A non-shocked control group was included in the design and two footshock intensities were employed (0.5 and 1.5 mA). Results showed clear evidence of contextual fear conditioning in preweanling and weanling rats, as well as evidence of conditioned fear in non-preexposed rats from both age groups. In some cases, some dependent variables, such as grooming or vertical exploration, were more sensitive than freezing for detecting evidence of memory. Strong fear responses were detected in weanling (but not preweanling) rats, when rats were evaluated in a different context from the one employed at conditioning. These results indicate that preweanling rats are capable of acquiring contextual conditioning, even in a context lacking explicit odor cues, and highlight the importance of multiple dependent variables for analyzing the ontogeny of memory.
Rangwala, Imtiaz; Sinsky, Eric; Miller, James R.
2016-04-01
The future rate of climate change in mountains has many potential human impacts, including those related to water resources, ecosystem services, and recreation. Analysis of the ensemble mean response of CMIP5 global climate models (GCMs) shows amplified warming in high elevation regions during the cold season in boreal midlatitudes. We examine how the twenty-first century elevation-dependent response in the daily minimum surface air temperature [d(ΔTmin)/dz] varies among 27 different GCMs during winter for the RCP 8.5 emissions scenario. The focus is on regions within the northern hemisphere mid-latitude band between 27.5°N and 40°N, which includes both the Rocky Mountains and the Tibetan Plateau/Himalayas. We find significant variability in d(ΔTmin)/dz among the individual models ranging from 0.16 °C/km (10th percentile) to 0.97 °C/km (90th percentile), although nearly all of the GCMs (24 out of 27) show a significant positive value for d(ΔTmin)/dz. To identify some of the important drivers associated with the variability in d(ΔTmin)/dz during winter, we evaluate the co-variance between d(ΔTmin)/dz and the differential response of elevation-based anomalies in different climate variables as well as the GCMs' spatial resolution, their global climate sensitivity, and their elevation-dependent free air temperature response. We find that d(ΔTmin)/dz has the strongest correlation with elevation-dependent increases in surface water vapor, followed by elevation-dependent decreases in surface albedo, and a weak positive correlation with the GCMs' free air temperature response.
Jerneja Kavčič
2004-12-01
Full Text Available In the present paper I investigate the use of the infinitive in dependent delibera tive clauses in Greek, a phenomenon occurring in several (modern languages, cf. Slovene Nisem vedel, kaj storiti. 'I didn't know what to do?', English I didn't know what to do., German Was tun? 'What to do?'l. In the first part I present the development of deliberative infinitive clauses in Post-Classical Greek with a special emphasis on the use of this form in two Early Byzantine prose writings (in Pratum Spirituale and in Vita Theodori Syceotae, both belonging to the 6th;7th century AD, where some peculiarities are observed. In the second part an attempt is made to interpret the basic characteristics of the Greek infinitive in dependent deliberative clauses from the perspective of Naturalness Theory.
Ke J
2015-07-01
Full Text Available Jun Ke,1,* Li Zhang,2,* Rongfeng Qi,1,* Qiang Xu,1 Weihui Li,2 Cailan Hou,3 Yuan Zhong,1 Zhiqiang Zhang,1 Zhong He,4 Lingjiang Li,2,5 Guangming Lu11Department of Medical Imaging, Jinling Hospital, Medical School of Nanjing University, Nanjing, 2Mental Health Institute, the Second Xiangya Hospital, National Technology Institute of Psychiatry, Key Laboratory of Psychiatry and Mental Health of Hunan Province, Central South University, Changsha, 3Guangdong Academy of Medical Science, Guangdong General Hospital, Guangdong Mental Health Center, Guangzhou, 4Department of Radiology of the Second Xiangya Hospital, Central South University, Changsha, 5Shenzhen Kangning Hospital of Guangdong Province, Shenzhen, People’s Republic of China*These authors contributed equally to this workBackground: Recent research suggests that variability in brain signal provides important information about brain function in health and disease. However, it is unknown whether blood oxygen level-dependent (BOLD signal variability is altered in post-traumatic stress disorder (PTSD. We aimed to identify the BOLD signal variability changes of PTSD patients during symptom provocation and compare the brain patterns of BOLD signal variability with those of brain activation.Methods: Twelve PTSD patients and 14 age-matched controls, who all experienced a mining accident, underwent clinical assessment as well as fMRI scanning while viewing trauma-related and neutral pictures. BOLD signal variability and brain activation were respectively examined with standard deviation (SD and general linear model analysis, and compared between the PTSD and control groups. Multiple regression analyses were conducted to explore the association between PTSD symptom severity and these two brain measures across all subjects as well as in the PTSD group.Results: PTSD patients showed increased activation in the middle occipital gyrus compared with controls, and an inverse correlation was found between PTSD
Tonini, C.; Jones, D. H.; Mould, J.; Webster, R. L.; Danilovich, T.; Ozbilgen, S.
2014-03-01
We investigate the morphology dependence of the Tully-Fisher (TF) relation, and the expansion of the relation into a three-dimensional manifold defined by luminosity, total circular velocity and a third dynamical parameter, to fully characterize spiral galaxies across all morphological types. We use a full semi-analytic hierarchical model (based on Croton et al.), built on cosmological simulations of structure formation, to model galaxy evolution and build the theoretical TF relation. With this tool, we analyse a unique data set of galaxies for which we cross-match luminosity with total circular velocity and central velocity dispersion. We provide a theoretical framework to calculate such measurable quantities from hierarchical semi-analytic models. We establish the morphology dependence of the TF relation in both model and data. We analyse the dynamical properties of the model galaxies and determine that the parameter σ/VC, i.e. the ratio between random and total motions defined by velocity dispersion and circular velocity, accurately characterizes the varying slope of the TF relation for different model galaxy types. We apply these dynamical cuts to the observed galaxies and find indeed that such selection produces a differential slope of the TF relation. The TF slope in different ranges of σ/VC is consistent with that for the traditional photometric classification in Sa, Sb and Sc. We conclude that σ/VC is a good parameter to classify galaxy type, and we argue that such classification based on dynamics more closely mirrors the physical properties of the observed galaxies, compared to visual (photometric) classification. We also argue that dynamical classification is useful for samples where eye inspection is not reliable or impractical. We conclude that σ/VC is a suitable parameter to characterize the hierarchical assembly history that determines the disc-to-bulge ratio, and to expand the TF relation into a three-dimensional manifold, defined by luminosity
Wang, Sheng-Dong; Zhou, Yong-Wu; Wang, Jun-Ping
2010-10-01
This article discusses production and order as well as advertising coordination issues in a single-manufacturer single-buyer supply chain, where the manufacturer sells a newsvendor-type product through the buyer who faces a random demand depending on advertising expenditure and selling price. The buyer has two ordering opportunities: the one happens before the beginning of the season, and the other takes place at the end of the season. The ordered items are produced by the manufacturer in two production modes for different requirements. The first production mode is relatively cheap but requires a long lead-time, whereas the second is expensive but offers quick response. Under such a setting, the centralised and decentralised decision models are developed, respectively, and the closed form solution to each model is provided as well. Moreover, we point out that the traditional revenue-sharing contract fails to coordinate the supply chain. We thus propose an improved revenue-sharing contract that requests the manufacturer not only shares the buyer's revenue but also bears a portion of the buyer's operating costs. Such a contract can achieve perfect coordination of the supply chain and arbitrarily allocate its profit between two parties.
Spitkovsky, A; Spitkovsky, Anatoly; Arons, Jonathan
2004-01-01
We describe results from time-dependent numerical modeling of the collisionless reverse shock terminating the pulsar wind in the Crab Nebula. We treat the upstream relativistic wind as composed of ions and electron-positron plasma embedded in a toroidal magnetic field, flowing radially outward from the pulsar in a sector around the rotational equator. The relativistic cyclotron instability of the ion gyrational orbit downstream of the leading shock in the electron-positron pairs launches outward propagating magnetosonic waves. Because of the fresh supply of ions crossing the shock, this time-dependent process achieves a limit-cycle, in which the waves are launched with periodicity on the order of the ion Larmor time. Compressions in the magnetic field and pair density associated with these waves, as well as their propagation speed, semi-quantitatively reproduce the behavior of the wisp and ring features described in recent observations obtained using the Hubble Space Telescope and the Chandra X-Ray Observator...
Time-dependent excitation and ionization modelling of absorption-line variability due to GRB 080310
Vreeswijk, P M; Raassen, A J J; Smette, A; De Cia, A; Woźniak, P R; Fox, A J; Vestrand, W T; Jakobsson, P
2012-01-01
We model the time-variable absorption of FeII, FeIII, SiII, CII and CrII detected in UVES spectra of GRB 080310, with the afterglow radiation exciting and ionizing the interstellar medium in the host galaxy at a redshift of z=2.42743. To estimate the rest-frame afterglow brightness as a function of time, we use a combination of the optical VRI photometry obtained by the RAPTOR-T telescope array -- which are presented in this paper -- and Swift's X-Ray Telescope observations. Excitation alone, which has been successfully applied for a handful of other GRBs, fails to describe the observed column-density evolution in the case of GRB 080310. Inclusion of ionization is required to explain the column-density decrease of all observed FeII levels (including the ground state 6D9/2) and increase of the FeIII 7S3 level. The large population of ions in this latter level (up to 10% of all FeIII) can only be explained through ionization of FeII, whereby a large fraction of the ionized FeII ions -- we calculate 31% using th...
Dependency of the Cusp Density Anomaly on the Variability of Forcing Inside and Outside the Cusp
Brinkman, D. G.; Walterscheid, R. L.; Clemmons, J. H.
2014-12-01
The Earth's magnetospheric cusp provides direct access of energetic particles to the thermosphere. These particles produce ionization and kinetic (particle) heating of the atmosphere. The increased ionization coupled with enhanced electric fields in the cusp produces increased Joule heating and ion drag forcing. These energy inputs largely determine the neutral density structure in the cusp region. Measurements by the CHAMP satellite (460-390- km altitude) have shown a region of strong enhanced density attributed to the combination of cusp particle and Joule heating. The Streak mission (325-123 km), on the other hand, observed a relative depletion in density in the cusp. While particle precipitation in the cusp is comparatively well constrained, the characteristics of the steady and fluctuating components of the electric field in the cusp are poorly constrained. Also, the significance of harder particle precipitation in areas adjacent to the cusp in particular at lower altitudes has not been addressed as it relates to the cusp density anomaly. We address the response of the cusp region to a range electrodynamical forcing with our high resolution two-dimensional time-dependent nonhydrostatic nonlinear dynamical model. We take advantage of our model's high resolution and focus on a more typical cusp width of 2 degrees in latitude. Earlier simulations have also shown a significant contribution from soft particle precipitation. We simulate the atmospheric response to a range of realizable magnitudes of the fluctuating and steady components of the electric field to examine the dependence of the magnitude of the cusp density anomaly on a large range of observed characteristics of the electrodynamical forcing and examine, in particular, the importance of particle heating relative to Joule heating. In addition we investigate the role of harder particle precipitation in areas adjacent to the cusp in determining the lower altitude cusp density and wind structure. We compare
Medyńska-Gulij, Beata; Cybulski, Paweł
2016-06-01
This paper analyses the use of table visual variables of statistical data of hospital beds as an important tool for revealing spatio-temporal dependencies. It is argued that some of conclusions from the data about public health and public expenditure on health have a spatio-temporal reference. Different from previous studies, this article adopts combination of cartographic pragmatics and spatial visualization with previous conclusions made in public health literature. While the significant conclusions about health care and economic factors has been highlighted in research papers, this article is the first to apply visual analysis to statistical table together with maps which is called previsualisation.
Medyńska-Gulij Beata
2016-06-01
Full Text Available This paper analyses the use of table visual variables of statistical data of hospital beds as an important tool for revealing spatio-temporal dependencies. It is argued that some of conclusions from the data about public health and public expenditure on health have a spatio-temporal reference. Different from previous studies, this article adopts combination of cartographic pragmatics and spatial visualization with previous conclusions made in public health literature. While the significant conclusions about health care and economic factors has been highlighted in research papers, this article is the first to apply visual analysis to statistical table together with maps which is called previsualisation.
Goudarzi, Nasser
2016-04-05
In this work, two new and powerful chemometrics methods are applied for the modeling and prediction of the (19)F chemical shift values of some fluorinated organic compounds. The radial basis function-partial least square (RBF-PLS) and random forest (RF) are employed to construct the models to predict the (19)F chemical shifts. In this study, we didn't used from any variable selection method and RF method can be used as variable selection and modeling technique. Effects of the important parameters affecting the ability of the RF prediction power such as the number of trees (nt) and the number of randomly selected variables to split each node (m) were investigated. The root-mean-square errors of prediction (RMSEP) for the training set and the prediction set for the RBF-PLS and RF models were 44.70, 23.86, 29.77, and 23.69, respectively. Also, the correlation coefficients of the prediction set for the RBF-PLS and RF models were 0.8684 and 0.9313, respectively. The results obtained reveal that the RF model can be used as a powerful chemometrics tool for the quantitative structure-property relationship (QSPR) studies.
Seismic hazard from induced seismicity: effect of time-dependent hazard variables
Convertito, V.; Sharma, N.; Maercklin, N.; Emolo, A.; Zollo, A.
2012-12-01
Geothermal systems are drawing large attention worldwide as an alternative source of energy. Although geothermal energy is beneficial, field operations can produce induced seismicity whose effects can range from light and unfelt to severe damaging. In a recent paper by Convertito et al. (2012), we have investigated the effect of time-dependent seismicity parameters on seismic hazard from induced seismicity. The analysis considered the time-variation of the b-value of the Gutenberg-Richter relationship and the seismicity rate, and assumed a non-homogeneous Poisson model to solve the hazard integral. The procedure was tested in The Geysers geothermal area in Northern California where commercial exploitation has started in the 1960s. The analyzed dataset consists of earthquakes recorded during the period 2007 trough 2010 by the LBNL Geysers/Calpine network. To test the reliability of the analysis, we applied a simple forecasting procedure which compares the estimated hazard values in terms of ground-motion values having fixed probability of exceedance and the observed ground-motion values. The procedure is feasible for monitoring purposes and for calibrating the production/extraction rate to avoid adverse consequences. However, one of the main assumptions we made concern the fact that both median predictions and standard deviation of the ground-motion prediction equation (GMPE) are stationary. Particularly for geothermal areas where the number of recorded earthquakes can rapidly change with time, we want to investigate how a variation of the coefficients of the used GMPE and of the standard deviation influences the hazard estimates. Basically, we hypothesize that the physical-mechanical properties of a highly fractured medium which is continuously perturbed by field operations can produce variations of both source and medium properties that cannot be captured by a stationary GMPE. We assume a standard GMPE which accounts for the main effects which modify the scaling
Graves, Catherine E.; Dávila, Noraica; Merced-Grafals, Emmanuelle J.; Lam, Si-Ty; Strachan, John Paul; Williams, R. Stanley
2017-03-01
Applications of memristor devices are quickly moving beyond computer memory to areas of analog and neuromorphic computation. These applications require the design of devices with different characteristics from binary memory, such as a large tunable range of conductance. A complete understanding of the conduction mechanisms and their corresponding state variable(s) is crucial for optimizing performance and designs in these applications. Here we present measurements of low bias I-V characteristics of 6 states in a Ta/ tantalum-oxide (TaOx)/Pt memristor spanning over 2 orders of magnitude in conductance and temperatures from 100 K to 500 K. Our measurements show that the 300 K device conduction is dominated by a temperature-insensitive current that varies with non-volatile memristor state, with an additional leakage contribution from a thermally-activated current channel that is nearly independent of the memristor state. We interpret these results with a parallel conduction model of Mott hopping and Schottky emission channels, fitting the voltage and temperature dependent experimental data for all memristor states with only two free parameters. The memristor conductance is linearly correlated with N, the density of electrons near EF participating in the Mott hopping conduction, revealing N to be the dominant state variable for low bias conduction in this system. Finally, we show that the Mott hopping sites can be ascribed to oxygen vacancies, where the local oxygen vacancy density responsible for critical hopping pathways controls the memristor conductance.
Saka, Boualem; Djouahri, Abderrahmane; Djerrad, Zineb; Souhila, Terfi; Aberrane, Sihem; Sabaou, Nasserdine; Baaliouamer, Aoumeur; Boudarene, Lynda
2017-02-01
In the present work, the Brassica rapa var. rapifera parts essential oils and their antioxidant and antimicrobial activities were investigated for the first time depending on geographic origin and extraction technique. GC and GC-MS analyses showed several constituents, including alcohols, aldehydes, esters, ketones, norisoprenoids, terpenic, nitrogen and sulphur compounds, totalizing 38 and 41 compounds in leaves and root essential oils, respectively. Nitrogen compounds were the main volatiles in leaves essential oils and sulphur compounds were the main volatiles in root essential oils. Qualitative and quantitative differences were found among B. rapa var. rapifera parts essential oils collected from different locations and extracted by hydrodistillation (HD) and microwave-assisted hydrodistillation (MAHD) techniques. Furthermore, our findings showed a high variability for both antioxidant and antimicrobial activities. The highlighted variability reflects the high impact of plant part, geographic variation and extraction technique on chemical composition and biological activities, which led to conclude that we should select essential oils to be investigated carefully depending on these factors, in order to isolate the bioactive components or to have the best quality of essential oil in terms of biological activities and preventive effects in food. This article is protected by copyright. All rights reserved.
Rapeli Pekka
2012-11-01
Full Text Available Abstract Background Cognitive deficits and multiple psychoactive drug regimens are both common in patients treated for opioid-dependence. Therefore, we examined whether the cognitive performance of patients in opioid-substitution treatment (OST is associated with their drug treatment variables. Methods Opioid-dependent patients (N = 104 who were treated either with buprenorphine or methadone (n = 52 in both groups were given attention, working memory, verbal, and visual memory tests after they had been a minimum of six months in treatment. Group-wise results were analysed by analysis of variance. Predictors of cognitive performance were examined by hierarchical regression analysis. Results Buprenorphine-treated patients performed statistically significantly better in a simple reaction time test than methadone-treated ones. No other significant differences between groups in cognitive performance were found. In each OST drug group, approximately 10% of the attention performance could be predicted by drug treatment variables. Use of benzodiazepine medication predicted about 10% of performance variance in working memory. Treatment with more than one other psychoactive drug (than opioid or BZD and frequent substance abuse during the past month predicted about 20% of verbal memory performance. Conclusions Although this study does not prove a causal relationship between multiple prescription drug use and poor cognitive functioning, the results are relevant for psychosocial recovery, vocational rehabilitation, and psychological treatment of OST patients. Especially for patients with BZD treatment, other treatment options should be actively sought.
Angstman, Nicholas B; Kiessling, Maren C; Frank, Hans-Georg; Schmitz, Christoph
2015-01-01
In blast-related mild traumatic brain injury (br-mTBI) little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI.
Chen, Xuhui; Liang, Edison; Boettcher, Markus
2011-01-01
(abridged) We present a new time-dependent multi-zone radiative transfer code and its application to study the SSC emission of Mrk 421. The code couples Fokker-Planck and Monte Carlo methods, in a 2D geometry. For the first time all the light travel time effects (LCTE) are fully considered, along with a proper treatment of Compton cooling, which depends on them. We study a set of simple scenarios where the variability is produced by injection of relativistic electrons as a `shock front' crosses the emission region. We consider emission from two components, with the second one either being pre-existing and co-spatial and participating in the evolution of the active region, or spatially separated and independent, only diluting the observed variability. Temporal and spectral results of the simulation are compared to the multiwavelength observations of Mrk 421 in March 2001. We find parameters that can adequately fit the observed SEDs and multiwavelength light curves and correlations. There remain however a few o...
Zhuo Chen
2015-01-01
Full Text Available Objective. The aim of this systematic review is to evaluate effect of Chinese medicine combined with conventional therapy on blood pressure variability (BPV in hypertension patients. Methods. All randomized clinical trials (RCTs comparing Chinese medicine with no intervention or placebo on the basis of conventional therapy were included. Data extraction, analyses, and quality assessment were performed according to the Cochrane standards. Results. We included 13 RCTs and assessed risk of bias for all the trials. Chinese medicine has a significant effect in lowering blood pressure (BP, reducing BPV in the form of standard deviation (SD or coefficient of variability (CV, improving nighttime BP decreased rate, and reversing abnormal rhythm of BP. Conclusions. Chinese medicine was safe and showed beneficial effects on BPV in hypertension patients. However, more rigorous trials with high quality are warranted to give high level of evidence before recommending Chinese medicine as an alternative or complementary medicine to improve BPV in hypertension patients.
Insulin-dependent glucose metabolism in dairy cows with variable fat mobilization around calving.
Weber, C; Schäff, C T; Kautzsch, U; Börner, S; Erdmann, S; Görs, S; Röntgen, M; Sauerwein, H; Bruckmaier, R M; Metges, C C; Kuhla, B; Hammon, H M
2016-08-01
clamps, pp nonesterified fatty acid concentrations did not reach the ap levels. The study demonstrated a minor influence of different degrees of body fat mobilization on insulin metabolism in cows during the transition period. The distinct decrease in the glucose-dependent release of insulin pp is the most striking finding that explains the impaired insulin action after calving, but does not explain differences in body fat mobilization between HLFC and LLFC cows.
Fenaux, P.; Giagounidis, A.; Selleslag, D.; Beyne-Rauzy, O.; Mufti, G.; Mittelman, M.; Muus, P.; Boekhorst, P. Te; Sanz, G.; Del Canizo, C.; Guerci-Bresler, A.; Nilsson, L.; Platzbecker, U.; Lubbert, M.; Quesnel, B.; Cazzola, M.; Ganser, A.; Bowen, D.; Schlegelberger, B.; Aul, C.; Knight, R.; Francis, J.; Fu, T.; Hellstrom-Lindberg, E.
2011-01-01
This phase 3, randomized, double-blind study assessed the efficacy and safety of lenalidomide in 205 red blood cell (RBC) transfusion-dependent patients with International Prognostic Scoring System Low-/Intermediate-1-risk del5q31 myelodysplastic syndromes. Patients received lenalidomide 10 mg/day o
Carroll, KJ; Mielke, J; Benet, LZ; Jones, B
2016-01-01
We previously demonstrated pharmacokinetic differences among manufacturing batches of a US Food and Drug Administration (FDA)‐approved dry powder inhalation product (Advair Diskus 100/50) large enough to establish between‐batch bio‐inequivalence. Here, we provide independent confirmation of pharmacokinetic bio‐inequivalence among Advair Diskus 100/50 batches, and quantify residual and between‐batch variance component magnitudes. These variance estimates are used to consider the type I error rate of the FDA's current two‐way crossover design recommendation. When between‐batch pharmacokinetic variability is substantial, the conventional two‐way crossover design cannot accomplish the objectives of FDA's statistical bioequivalence test (i.e., cannot accurately estimate the test/reference ratio and associated confidence interval). The two‐way crossover, which ignores between‐batch pharmacokinetic variability, yields an artificially narrow confidence interval on the product comparison. The unavoidable consequence is type I error rate inflation, to ∼25%, when between‐batch pharmacokinetic variability is nonzero. This risk of a false bioequivalence conclusion is substantially higher than asserted by regulators as acceptable consumer risk (5%). PMID:27727445
Ohtani, Maki; Hikima, Jun-ichi; Jung, Tae Sung; Kondo, Hidehiro; Hirono, Ikuo; Aoki, Takashi
2013-02-01
To develop a multi-antigen-specific immunoglobulin new antigen receptor (IgNAR) variable (V) region phage display library, CDR3 in the V region of IgNAR from banded houndshark (Triakis scyllium) was artificially randomized, and clones specific for hen egg white lysozyme (HEL) were obtained by the biopanning method. The nucleotide sequence of CDR3 in the V region was randomly rearranged by PCR. Randomized CDR3-containing segments of the V region were ligated into T7 phage vector to construct a phage display library and resulted in a phage titer of 3.7 × 10(7) PFU/ml. Forty clones that contained randomized CDR3 inserts were sequenced and shown to have different nucleotide sequences. The HEL-specific clones were screened by biopanning using HEL-coated ELISA plates. After six rounds of screening, nine clones were identified as HEL-specific, eight of which showed a strong affinity to HEL in ELISA compared to a negative control (i.e., empty phage clone). The deduced amino acid sequences of CDR3 from the HEL-specific phage clones fell into four types (I-IV): type I contains a single cysteine residue and type II-IV contain two cysteine residues. These results indicated that the artificially randomized IgNAR library is useful for the rapid isolation of antigen-specific IgNAR V region without immunization of target antigen and showed that it is possible to isolate an antigen-specific IgNAR V region from this library.
Elibet Chávez González
2013-09-01
Full Text Available Introduction:The relationship between diastolic dysfunction and P-wave dispersion (PWD in the electrocardiogram has been studied for some time. In this regard, echocardiography is emerging as a diagnostic tool to improve risk stratification for mild hypertension.Objective:To determine the dependence of PWD on the electrocardiogram and on echocardiographic variables in a pediatric population.Methods: Five hundred and fifteen children from three elementary schools were studiedfrom a total of 565 children. Those whose parents did not want them to take part in the study, as well as those with known congenital diseases, were excluded. Tests including 12-lead surface ECGs and 4 blood pressure (BP measurements were performed. Maximum and minimum P-values were measured, and the PWD on the electrocardiogram was calculated. Echocardiography for structural measurements and the pulsed Doppler of mitral flow were also performed.Results: A significant correlation in statistical variables was found between PWD and mean BP for pre-hypertensive and hypertensive children, i.e., r= 0.32, p <0.01 and r= 0.33, p <0.01, respectively. There was a significant correlation found between PWD and the left atrial area (r= 0.45 and p <0.01.Conclusions: We highlight the dependency between PWD, the electrocardiogram and mean blood pressure. We also draw attention to the dependence of PWD on the left atrial area. This result provides an explanation for earlier changes in atrial electrophysiological and hemodynamic characteristics in pediatric patients.
Miller, Tom E X
2007-07-01
1. It is widely accepted that density-dependent processes play an important role in most natural populations. However, persistent challenges in our understanding of density-dependent population dynamics include evaluating the shape of the relationship between density and demographic rates (linear, concave, convex), and identifying extrinsic factors that can mediate this relationship. 2. I studied the population dynamics of the cactus bug Narnia pallidicornis on host plants (Opuntia imbricata) that varied naturally in relative reproductive effort (RRE, the proportion of meristems allocated to reproduction), an important plant quality trait. I manipulated per-plant cactus bug densities, quantified subsequent dynamics, and fit stage-structured models to the experimental data to ask if and how density influences demographic parameters. 3. In the field experiment, I found that populations with variable starting densities quickly converged upon similar growth trajectories. In the model-fitting analyses, the data strongly supported a model that defined the juvenile cactus bug retention parameter (joint probability of surviving and not dispersing) as a nonlinear decreasing function of density. The estimated shape of this relationship shifted from concave to convex with increasing host-plant RRE. 4. The results demonstrate that host-plant traits are critical sources of variation in the strength and shape of density dependence in insects, and highlight the utility of integrated experimental-theoretical approaches for identifying processes underlying patterns of change in natural populations.
Huixin Tian
2016-01-01
Full Text Available Different from most researches focused on the single objective hybrid flowshop scheduling (HFS problem, this paper investigates a biobjective HFS problem with sequence dependent setup time. The two objectives are the minimization of total weighted tardiness and the total setup time. To efficiently solve this problem, a Pareto-based adaptive biobjective variable neighborhood search (PABOVNS is developed. In the proposed PABOVNS, a solution is denoted as a sequence of all jobs and a decoding procedure is presented to obtain the corresponding complete schedule. In addition, the proposed PABOVNS has three major features that can guarantee a good balance of exploration and exploitation. First, an adaptive selection strategy of neighborhoods is proposed to automatically select the most promising neighborhood instead of the sequential selection strategy of canonical VNS. Second, a two phase multiobjective local search based on neighborhood search and path relinking is designed for each selected neighborhood. Third, an external archive with diversity maintenance is adopted to store the nondominated solutions and at the same time provide initial solutions for the local search. Computational results based on randomly generated instances show that the PABOVNS is efficient and even superior to some other powerful multiobjective algorithms in the literature.
Rössler, Ole; Bosshard, Thomas; Weingartner, Rolf
2016-04-01
A key issue for adaptation planning is the information of projections about changes of extremes. Climate projections of meteorological extremes and their downscaling are a challenge on their own. Yet - at least in hydrology - meteorological extremes are not necessarily hydrological extremes. These can also result from a sequence of days with only moderate meteorological conditions, too. This sequences are called "storylines". In climate change impact assess studies it is relevant to know, whether these meteorological storylines are represented in regional climate models, and how well can bias correction preserve or improve the representation. One storyline leading to hydrological extremes are rain-on-snow events, and more specifically rain-on-snowfall events. These events challenge the regional climate model and the bias correction in terms of representing absolute values and inter-variable dependences. This study makes use of the rain-on-snow-storylines to evaluate the performance of regional climate models and a bias correction method in reproducing complex inter-variable dependencies. At first, we applied a hydrological model to a mesoscale catchment in Switzerland that is known to be effected by rain-on-snow events. At second, the ERA-Interim driven regional climate model RCA4.5 - developed at SMHI - with a spatial resolution of 0.11 * 0.11 degree was used to drive the hydrological model. At third, bias-correction of the RCM was done applying the distribution based scaling (DBS) bias-correction method (Yang et al., 2010) developed at the SMHI. The bias-corrected data then also served as driving input data to the hydrological model. Based on the simulated runoff, as well as simulated precipitation, temperature, and snow pack data, an algorithm to detect rain-on-snow events was applied. Finally, the presence or absents of rain-on-snow events for the three different climate input data, ERA.RCA4.5, DBS corrected ERA.RC4 and observed climate, are evaluated within
Kushnir, Yochanan; Wallace, John M.
1989-10-01
Low-frequency variability in wintertime 500 mb height is examined, with emphasis on its structure, geographical distribution, and frequency dependence. A 39-year record of 500 mb geopotential height fields from the NMC analyses is time filtered to partition the fluctuations into frequency bands corresponding to periods of 10-60 days, 60-180 days and > 180 days. Winter is defined as the six month period November through April. Variance, teleconnectivity, and anisotropy fields, and selected loading vectors derived from orthogonal and oblique rotations of the eigenvectors of the temporal correlation matrix for each band are shown and discussed.The variability in all frequency bands exhibits substantial anistropy, with meridionally elongated features arranged as zonally oriented wave trains prevailing over the continents and zonally elongated features organized in the form of north-south oriented dipole patterns prevailing over the oceanic sectors of the hemisphere. The wave trains are most pronounced in the 10-60 day variability, while the dipoles are most pronounced at lower frequencies. Eastward energy dispersion is apparent in the wave trains, but there is no evidence of phase propagation.Most of the `teleconnection patterns' identified in previous studies appear among the more prominent loading vectors. However, in most cases the loading vectors occur in pairs, in which the two patterns are in spatial quadrature with one another and account for comparable fractions of the hemispherically integrated variance. It is argued that such patterns should be interpreted as basis functions that can be linearly combined to form a continuum of anisotropic structures. Evidence of the existence of discrete `modal structures' is found only in the interannual (> 180-day period) variability, where two patterns stand out clearly above the background continuum: the Pacific-North American (PNA) pattern and the North Atlantic Oscillation (NAO). These patterns leave clear imprints upon
Dong Wang; Steven J. Ruuth
2008-01-01
Implicit-explicit (IMEX) linear multistep methods are popular techniques for solving partial differential equations (PDEs) with terms of different types. While fixed time-step versions of such schemes have been developed and studied, implicit-explicit schemes also naturally arise in general situations where the temporal smoothness of the solution changes. In this paper we consider easily implementable variable step-size implicit-explicit (VSIMEX) linear multistep methods for time-dependent PDEs. Families of order-p, p-step VSIMEX schemes are constructed and analyzed, where p ranges from 1 to 4. The corresponding schemes are simple to implement and have the property that they reduce to the classical IMEX schemes whenever constant time step-sizes are imposed. The methods are validated on the Burgers' equation. These results demonstrate that by varying the time step-size, VSIMEX methods can outperform their fixed time step counterparts while still maintaining good numerical behavior.
Röken, Christian; Schöneberg, Sebastian; Schuppan, Florian
2016-01-01
A leptonic one-zone model accounting for the radiation emission of blazars is presented. This model describes multiple successive injections of mono-energetic, ultra-relativistic, interacting electron populations, which are subjected to synchrotron and synchrotron-self Compton radiative losses. The electron number density is computed analytically by solving a time-dependent, relativistic transport equation. Moreover, the synchrotron and synchrotron-self Compton intensities as well as the corresponding total fluences are explicitly calculated. The lightcurves and fluences are plotted for realistic parameter values, showing that the model can simultaneously explain both the specific short-time variability in the flaring of blazars and the characteristic broad-band fluence behavior.
Jeen-Hwa Wang
2009-01-01
The two one-state-variable, rate- and state-dependent friction laws, i.e., the slip and slowness laws, are compared on the basis of dynamical behavior of a one-degree-of-freedom spring-slider model through numerical simulations. Results show that two (normalized) model parameters, i.e., △(the normalized characteristic slip distance) and β-α (the difference in two normalized parameters of friction laws), control the solutions. From given values of △, β, and α, for the slowness laws, the solution exists and the unique non-zero fixed point is stable when △>(β-α), yet not when △<β-α). For the slip law, the solution exists for large ranges of model parameters and the number and stability of the non-zero fixed points change from one case to another. Results suggest that the slip law is more appropriate for controlling earthquake dynamics than the slowness law.
Ohtani, Maki; Hikima, Jun-ichi; Jung, Tae-Sung; Kondo, Hidehiro; Hirono, Ikuo; Takeyama, Haruko; Aoki, Takashi
2013-02-01
Phage display libraries are used to screen for nucleotide sequences that encode immunoglobulin variable (V) regions that are specific for a target antigen. We previously constructed an immunoglobulin new antigen receptor (IgNAR) phage display library. Here we used this library to obtain an IgNAR V region that is specific for viral hemorrhagic septicemia virus (VHSV). A phage clone (clone 653) was found to be specific for VHSV by the biopanning method. The V region of clone 653 was used to construct a 6 × His tagged recombinant IgNAR-653 V protein (rIgNAR-653) using the Escherichia coli pET system. The rIgNAR-653 protein bound specifically to VHSV, confirming its activity.
Nicholas Baker Angstman
2015-02-01
Full Text Available In blast-related mild traumatic brain injury (br-mTBI little is known about the connections between initial trauma and expression of individual clinical symptoms. Partly due to limitations of current in vitro and in vivo models of br-mTBI, reliable prediction of individual short- and long-term symptoms based on known blast input has not yet been possible. Here we demonstrate a dose-dependent effect of shock wave exposure on C. elegans using shock waves that share physical characteristics with those hypothesized to induce br-mTBI in humans. Increased exposure to shock waves resulted in decreased mean speed of movement while increasing the proportion of worms rendered paralyzed. Recovery of these two behavioral symptoms was observed during increasing post-traumatic waiting periods. Although effects were observed on a population-wide basis, large interindividual variability was present between organisms exposed to the same highly controlled conditions. Reduction of cavitation by exposing worms to shock waves in polyvinyl alcohol resulted in reduced effect, implicating primary blast effects as damaging components in shock wave induced trauma. Growing worms on NGM agar plates led to the same general results in initial shock wave effect in a standard medium, namely dose-dependence and high interindividual variability, as raising worms in liquid cultures. Taken together, these data indicate that reliable prediction of individual clinical symptoms based on known blast input as well as drawing conclusions on blast input from individual clinical symptoms is not feasible in br-mTBI.
Douw, Linda; Wakeman, Daniel G; Tanaka, Naoaki; Liu, Hesheng; Stufflebeam, Steven M
2016-12-17
The brain is a dynamic, flexible network that continuously reconfigures. However, the neural underpinnings of how state-dependent variability of dynamic functional connectivity (vdFC) relates to cognitive flexibility are unclear. We therefore investigated flexible functional connectivity during resting-state and task-state functional magnetic resonance imaging (rs-fMRI and t-fMRI, resp.) and performed separate, out-of-scanner neuropsychological testing. We hypothesize that state-dependent vdFC between the frontoparietal network (FPN) and the default mode network (DMN) relates to cognitive flexibility. Seventeen healthy subjects performed the Stroop color word test and underwent t-fMRI (Stroop computerized version) and rs-fMRI. Time series were extracted from a cortical atlas, and a sliding window approach was used to obtain a number of correlation matrices per subject. vdFC was defined as the standard deviation of connectivity strengths over these windows. Higher task-state FPN-DMN vdFC was associated with greater out-of-scanner cognitive flexibility, while the opposite relationship was present for resting-state FPN-DMN vdFC. Moreover, greater contrast between task-state and resting-state vdFC related to better cognitive performance. In conclusion, our results suggest that not only the dynamics of connectivity between these networks is seminal for optimal functioning, but also that the contrast between dynamics across states reflects cognitive performance.
Chen, Xuhui; Liang, Edison; Boettcher, Markus
2012-01-01
[abridged] We present results of modeling the SED and multiwavelength variability of the bright FSRQ PKS1510-089 with our time-dependent multizone Monte Carlo/Fokker-Planck code (Chen et al. 2001). As primary source of seed photons for inverse Compton scattering, we consider radiation from the broad line region (BLR), from the molecular torus, and the local synchrotron radiation (SSC). Different scenarios are assessed by comparing simulated light curves and SEDs with one of the best flares by PKS1510-089, in March 2009. The time-dependence of our code and its correct handling of light travel time effects allow us to fully take into account the effect of the finite size of the active region, and in turn to fully exploit the information carried by time resolved observed SEDs, increasingly available since the launch of Fermi. We confirm that the spectrum adopted for the external radiation has an important impact on the modeling of the SED, in particular for the lower energy end of the Compton component, observed...
Cohen; Heller
2000-03-27
We consider a classically chaotic system that is described by a Hamiltonian H(Q,P;x), where x is a constant parameter. Specifically, we discuss a gas particle inside a cavity, where x controls a deformation of the boundary or the position of a "piston." The quantum eigenstates of the system are |n(x)>. We describe how the parametric kernel P(nmid R:m) = ||(2) evolves as a function of deltax = x-x(0). We explore both the perturbative and the nonperturbative regimes, and discuss the capabilities and the limitations of semiclassical as well as random waves and random-matrix-theory considerations.
Christiansen, Stig Hill; Zhang, Xianwei; Juul-Madsen, Kristian;
2017-01-01
The formulation glatiramer acetate (GA) is widely used in therapy of multiple sclerosis. GA consists of random copolymers of four amino acids, in ratios that produce a predominantly positive charge and an amphipathic character. With the extraordinary complexity of the drug, several pharmacological...
Sacanna, S.; Rossi, L.; Wouterse, A.; Philipse, A.P.
2007-01-01
We have measured the random packing density of monodisperse colloidal silica ellipsoids with a well-defined shape, gradually deviating from a sphere shape up to prolates with aspect ratios of about 5, to find for a colloidal system the first experimental observation for the density maximum (at an as
Hester, Reid K.; Delaney, Harold D.; Campbell, William
2011-01-01
Objective: To evaluate the effectiveness of a web-based protocol, ModerateDrinking.com (MD; "www.moderatedrinking.com") combined with use of the online resources of Moderation Management (MM; "www.moderation.org") as opposed to the use of the online resources of MM alone. Method: We randomly assigned 80 problem drinkers to…
Schwarz, Anne-Sophie; Bilberg, Randi; Bjerregaard, Lene Berit Skov;
2016-01-01
- The Relay Model. METHOD/DESIGN: The study is a single-blind pragmatic randomized controlled trial including patients admitted to the hospital. The study group (n = 500) will receive an intervention, and the control group (n = 500) will be referred to treatment by usual procedures. All patients complete...
A Class of Limit Theorems of Moving Averages for END Random Variables%END随机序列滑动平均的若干极限定理
胡松; 汪忠志
2013-01-01
利用条件E(exp{t?X1|1/p})＜∞,(p＞1),证明END随机序列滑动平均的极限定理,给出形如(logn)-p(n+(log n)p)∑(k=n+1)Xk的滑动平均的上下界,得到了经典强大数定律.%The classical strong law of large numbers is generalized to the case of END random variables of the form (logn)-p/(n+(logn)p) Σ(k=n+1) Xk with the condition E(exp{t∣X1∣1/p})＜∞,(p>l), by identifying its upper and lower limit.
Menezes, Regina; Rodriguez-Mateos, Ana; Kaltsatou, Antonia; González-Sarrías, Antonio; Greyling, Arno; Giannaki, Christoforos; Andres-Lacueva, Cristina; Milenkovic, Dragan; Gibney, Eileen R.; Dumont, Julie; Schär, Manuel; Garcia-Aloy, Mar; Palma-Duran, Susana Alejandra; Ruskovska, Tatjana; Maksimova, Viktorija; Combet, Emilie; Pinto, Paula
2017-01-01
Several epidemiological studies have linked flavonols with decreased risk of cardiovascular disease (CVD). However, some heterogeneity in the individual physiological responses to the consumption of these compounds has been identified. This meta-analysis aimed to study the effect of flavonol supplementation on biomarkers of CVD risk such as, blood lipids, blood pressure and plasma glucose, as well as factors affecting their inter-individual variability. Data from 18 human randomized controlled trials were pooled and the effect was estimated using fixed or random effects meta-analysis model and reported as difference in means (DM). Variability in the response of blood lipids to supplementation with flavonols was assessed by stratifying various population subgroups: age, sex, country, and health status. Results showed significant reductions in total cholesterol (DM = −0.10 mmol/L; 95% CI: −0.20, −0.01), LDL cholesterol (DM = −0.14 mmol/L; 95% CI: −0.21, 0.07), and triacylglycerol (DM = −0.10 mmol/L; 95% CI: −0.18, 0.03), and a significant increase in HDL cholesterol (DM = 0.05 mmol/L; 95% CI: 0.02, 0.07). A significant reduction was also observed in fasting plasma glucose (DM = −0.18 mmol/L; 95% CI: −0.29, −0.08), and in blood pressure (SBP: DM = −4.84 mmHg; 95% CI: −5.64, −4.04; DBP: DM = −3.32 mmHg; 95% CI: −4.09, −2.55). Subgroup analysis showed a more pronounced effect of flavonol intake in participants from Asian countries and in participants with diagnosed disease or dyslipidemia, compared to healthy and normal baseline values. In conclusion, flavonol consumption improved biomarkers of CVD risk, however, country of origin and health status may influence the effect of flavonol intake on blood lipid levels. PMID:28208791
Nuria eRuffini
2015-08-01
Full Text Available Context: Heart Rate Variability (HRV indicates how heart rate changes in response to inner and external stimuli. HRV is linked to health status and it is an indirect marker of the autonomic nervous system (ANS function. Objective: To investigate the influence of osteopathic manipulative treatment (OMT on ANS activity through changes of High Frequency, a heart rate variability index indicating the parasympathetic activity, in healthy subjects, compared with sham therapy and control group.Methods: Sixty-six healthy subjects, both male and female, were included in the present 3-armed randomized placebo controlled within subject cross-over single blinded study. Participants were asymptomatic adults, both smokers and non-smokers and not on medications. At enrollment subjects were randomized in 3 groups: A, B, C. Standardized structural evaluation followed by a patient need-based osteopathic treatment was performed in the first session of group A and in the second session of group B. Standardized evaluation followed by a protocoled sham treatment was provided in the second session of group A and in the first session of group B. No intervention was performed in the two sessions of group C, acting as a time-control. The trial was registered on clinicaltrials.gov identifier: NCT01908920.Main Outcomes Measures: HRV was calculated from electrocardiography before, during and after the intervention, for a total amount time of 25 minutes.Results: OMT engendered a statistically significant increase of parasympathetic activity, as shown by High Frequency rate (p<0.001, and decrease of sympathetic activity, as revealed by Low Frequency rate (p<0.01; results also showed a reduction of Low Frequency/High Frequency ratio (p<0.001 and Detrended fluctuation scaling exponent (p<0.05. Conclusions: Findings suggested that OMT can influence ANS activity increasing parasympathetic function and decreasing sympathetic activity, compared to sham therapy and control group.
属性值为正态随机变量的多属性决策方法%A method for MADM with normal random variables
姜广田; 樊治平
2012-01-01
针对具有正态随机变量的多属性决策(MADM)问题,提出了一种决策分析方法.在该方法中,首先通过理论分析给出根据期望和方差确定正态随机变量随机占优关系的简便方法；其次依据得到的简便方法确定针对各属性的两两方案之间的随机占优关系,并构建相应的随机占优关系矩阵;在此基础上,给出了一种基于ELECTRE Ⅲ的方案排序方法.最后,通过一个算例说明了所给方法的可行性和有效性.%This paper proposes a method to solve the multiple attribute decision making (MADM) problem with normal random variables. Firstly, a simple approach for identifying the stochastic dominance relation between a pair of normal random variables based on the expectations and variance values is given by theoretical analysis. Then, the dominance relation matrix with regard to each attribute is built according to the simple approach. Furthermore, ELECTRE III method is used to obtain the ranking result of alternatives. Finally, a numerical example is used to illustrate the feasibility and validity of proposed method.
Izaguirre, Cristina; Mendez, Fernando J.; Camus, Paula; Minguez, Roberto; Menendez, Melisa; Losada, Iñigo J.
2010-05-01
It is well known that the seasonal-to-interannual variability of extreme wave climate is linked to the anomalies of the atmosphere circulation. In this work, we analyze the relationships between extreme significant wave height at a particular site and the synoptic-scale weather type. We combine a time-dependent Generalized Extreme Value (GEV) model for monthly maxima and self-organizing maps (SOM) applied to monthly mean sea level pressure field (SLP) anomalies. These time-varying SLP anomalies are encoded using principal component analysis, obtaining the corresponding spatial patterns (Empirical Orthogonal Functions, EOFs) and the temporal modes (PC, principal components). The location, scale and shape parameters of the GEV distribution are parameterized in terms of harmonic functions (seasonality) and linear covariates for the PCs (interannual variability) and the model is fitted using standard likelihood theory and an automatic parameter selection procedure, which avoids overparameterization. Thus, the resulting anomalies of the location and scale parameters with respect to the seasonality are projected to the SOM lattice obtaining the influence of every weather type on the extreme wave height probability distribution (and subsequently, return-level quantiles). The use of Self-organizing maps allows an easy visualization of the results. The application of the method to different areas in the North Atlantic Ocean helps us to quantify the importance of the North Atlantic Oscillation and the East Atlantic pattern in the location and scale parameters of the GEV probability distribution. Additionally, this work opens new forecasting possibilities for the probabilities of extreme events based on synoptic-scale patterns.
Svozil, J; Baerenfaller, K
2017-01-01
Mass spectrometry-based proteomics allows in principle the identification of unknown target proteins of posttranslational modifications and the sites of attachment. Including a variety of posttranslational modifications in database-dependent searches of high-throughput mass spectrometry data holds the promise to gain spectrum assignments to modified peptides, thereby increasing the number of assigned spectra, and to identify potentially interesting modification events. However, these potential benefits come for the price of an increased search space, which can lead to reduced scores, increased score thresholds, and erroneous peptide spectrum matches. We have assessed here the advantages and disadvantages of including the variable posttranslational modifications methionine oxidation, protein N-terminal acetylation, cysteine carbamidomethylation, transformation of N-terminal glutamine to pyroglutamic acid (Gln→pyro-Glu), and deamidation of asparagine and glutamine. Based on calculations of local false discovery rates and comparisons to known features of the respective modifications, we recommend for searches of samples that were not enriched for specific posttranslational modifications to only include methionine oxidation, protein N-terminal acetylation, and peptide N-terminal Gln→pyro-Glu as variable modifications. The principle of the validation strategy adopted here can also be applied for assessing the inclusion of posttranslational modifications for differently prepared samples, or for additional modifications. In addition, we have reassessed the special properties of the ubiquitin footprint, which is the remainder of ubiquitin moieties attached to lysines after tryptic digest. We show here that the ubiquitin footprint often breaks off as neutral loss and that it can be distinguished from dicarbamidomethylation events.
Li, Hong-Dong; Xu, Qing-Song; Liang, Yi-Zeng
2012-08-31
The identification of disease-relevant genes represents a challenge in microarray-based disease diagnosis where the sample size is often limited. Among established methods, reversible jump Markov Chain Monte Carlo (RJMCMC) methods have proven to be quite promising for variable selection. However, the design and application of an RJMCMC algorithm requires, for example, special criteria for prior distributions. Also, the simulation from joint posterior distributions of models is computationally extensive, and may even be mathematically intractable. These disadvantages may limit the applications of RJMCMC algorithms. Therefore, the development of algorithms that possess the advantages of RJMCMC methods and are also efficient and easy to follow for selecting disease-associated genes is required. Here we report a RJMCMC-like method, called random frog that possesses the advantages of RJMCMC methods and is much easier to implement. Using the colon and the estrogen gene expression datasets, we show that random frog is effective in identifying discriminating genes. The top 2 ranked genes for colon and estrogen are Z50753, U00968, and Y10871_at, Z22536_at, respectively. (The source codes with GNU General Public License Version 2.0 are freely available to non-commercial users at: http://code.google.com/p/randomfrog/.).
Page, M. T.; Hardebeck, J.; Felzer, K. R.; Michael, A. J.; van der Elst, N.
2015-12-01
Following a large earthquake, seismic hazard can be orders of magnitude higher than the long-term average as a result of aftershock triggering. Due to this heightened hazard, there is a demand from emergency managers and the public for rapid, authoritative, and reliable aftershock forecasts. In the past, USGS aftershock forecasts following large, global earthquakes have been released on an ad-hoc basis with inconsistent methods, and in some cases, aftershock parameters adapted from California. To remedy this, we are currently developing an automated aftershock product that will generate more accurate forecasts based on the Reasenberg and Jones (Science, 1989) method. To better capture spatial variations in aftershock productivity and decay, we estimate regional aftershock parameters for sequences within the Garcia et al. (BSSA, 2012) tectonic regions. We find that regional variations for mean aftershock productivity exceed a factor of 10. The Reasenberg and Jones method combines modified-Omori aftershock decay, Utsu productivity scaling, and the Gutenberg-Richter magnitude distribution. We additionally account for a time-dependent magnitude of completeness following large events in the catalog. We generalize the Helmstetter et al. (2005) equation for short-term aftershock incompleteness and solve for incompleteness levels in the global NEIC catalog following large mainshocks. In addition to estimating average sequence parameters within regions, we quantify the inter-sequence parameter variability. This allows for a more complete quantification of the forecast uncertainties and Bayesian updating of the forecast as sequence-specific information becomes available.
Using XMM-Newton to study the energy dependent variability of H 1743-322 during its 2014 outburst
Stiele, H
2016-01-01
Black hole transients during bright outbursts show distinct changes of their spectral and variability properties as they evolve during an outburst, that are interpreted as evidence for changes in the accretion flow and X-ray emitting regions. We obtained an anticipated XMM-Newton ToO observation of H 1743-322 during its outburst in September 2014. Based on data of eight outbursts observed in the last 10 years we expected to catch the start of the hard-to-soft state transition. The fact that neither the general shape of the observed power density spectrum nor the characteristic frequency show an energy dependence implies that the source still stays in the low-hard state at the time of our observation near outburst peak. The spectral properties agree with the source being in the low-hard state and a Swift/XRT monitoring of the outburst reveals that H 1743-322 stays in the low-hard state during the entire outburst (a. k. a. 'failed outburst'). We derive the averaged QPO waveform and obtain phase-resolved spectra...
Boufadel, Michel C.; Suidan, Makram T.; Venosa, Albert D.
1999-04-01
We present a formulation for water flow and solute transport in two-dimensional variably saturated media that accounts for the effects of the solute on water density and viscosity. The governing equations are cast in a dimensionless form that depends on six dimensionless groups of parameters. These equations are discretized in space using the Galerkin finite element formulation and integrated in time using the backward Euler scheme with mass lumping. The modified Picard method is used to linearize the water flow equation. The resulting numerical model, the MARUN model, is verified by comparison to published numerical results. It is then used to investigate beach hydraulics at seawater concentration (about 30 g l -1) in the context of nutrients delivery for bioremediation of oil spills on beaches. Numerical simulations that we conducted in a rectangular section of a hypothetical beach revealed that buoyancy in the unsaturated zone is significant in soils that are fine textured, with low anisotropy ratio, and/or exhibiting low physical dispersion. In such situations, application of dissolved nutrients to a contaminated beach in a freshwater solution is superior to their application in a seawater solution. Concentration-engendered viscosity effects were negligible with respect to concentration-engendered density effects for the cases that we considered.
Christiansen, Stig Hill; Zhang, Xianwei; Juul-Madsen, Kristian;
2017-01-01
The formulation glatiramer acetate (GA) is widely used in therapy of multiple sclerosis. GA consists of random copolymers of four amino acids, in ratios that produce a predominantly positive charge and an amphipathic character. With the extraordinary complexity of the drug, several pharmacological...... contacts, which is critical for the lytic properties. In our study, SAXS showed that GA also forms this type of contacts. Taken together, our study offers new insight on the immunomodulatory mode-of-action of positively charged co-polymers. The comparison of LL-37 and GA highlights a consistent requirement...
Silvilairat, Suchaya; Charoenkwan, Pimlak; Saekho, Suwit; Tantiworawit, Adisak; Phrommintikul, Arintaya; Srichairatanakool, Somdet; Chattipakorn, Nipon
2016-01-01
Background Iron overload cardiomyopathy remains the major cause of death in patients with transfusion-dependent thalassemia. Cardiac T2* magnetic resonance imaging is costly yet effective in detecting cardiac iron accumulation in the heart. Heart rate variability (HRV) has been used to evaluate cardiac autonomic function and is depressed in cases of thalassemia. We evaluated whether HRV could be used as an indicator for early identification of cardiac iron deposition. Methods One hundred and one patients with transfusion-dependent thalassemia were enrolled in this study. The correlation between recorded HRV and hemoglobin, non-transferrin bound iron (NTBI), serum ferritin and cardiac T2* were evaluated. Results The median age was 18 years (range 8–59 years). The patient group with a 5-year mean serum ferritin >5,000 ng/mL included significantly more homozygous β-thalassemia and splenectomized patients, had lower hemoglobin levels, and had more cardiac iron deposit than all other groups. Anemia strongly influenced all domains of HRV. After adjusting for anemia, neither serum ferritin nor NTBI impacted the HRV. However cardiac T2* was an independent predictor of HRV, even after adjusting for anemia. For receiver operative characteristic (ROC) curve analysis of cardiac T2* ≤20 ms, only mean ferritin in the last 12 months and the average of the standard deviation of all R-R intervals for all five-minute segments in the 24-hour recording were predictors for cardiac T2* ≤20 ms, with area under the ROC curve of 0.961 (p<0.0001) and 0.701 (p = 0.05), respectively. Conclusions Hemoglobin and cardiac T2* as significant predictors for HRV indicate that anemia and cardiac iron deposition result in cardiac autonomic imbalance. The mean ferritin in the last 12 months could be useful as the best indicator for further evaluation of cardiac risk. The ability of serum ferritin to predict cardiac risk is stronger than observed in other thalassemia cohorts. HRV might be a
Fang-xiao Guan; Jing Wang; Ji-lin Pan; Qing Wang; Lei Zhua
2011-01-01
We studied cycle time (0.01-10 s with triangular input waves) and poling history (continuous versus fresh poling) dependent electric energy storage and discharge behaviors in poly(vinylidene fluoride-co-hexafluoropropylene) [P(VDFHFP)] films using the electric displacement — the electric field (D-E) hysteresis loop measurements. Since the permanent dipoles in PVDF are orientational in nature, it is generally considered that both charging and discharging processes should be time and poling history dependent. Intriguingly, our experimental results showed that the charging process depended heavily on the cycle time and the prior poling history, and thus the D-E hysteresis loops had different shapes accordingly. However, the discharged energy density did not change no matter how the D-E loop shape varied due to different measurements. This experimental result could be explained in terms of reversible and irreversible polarizations. The reversible polarization could be charged and discharged fairly quickly (＜ 5 ms for each process), while the irreversible polarization depended heavily on the poling time and the prior poling history. This study suggests that it is only meaningful to compare the discharged energy density for PVDF and its copolymer films when different cycle times and poling histories are used.
Bender, Stefan; Scherbaum, Norbert; Soyka, Michael; Rüther, Eckart; Mann, Karl; Gastpar, Markus
2007-10-01
In this investigation, the hypothesis was tested whether the selective dopamine D2/D3 receptor antagonist tiapride is effective in maintaining abstinence after detoxification in alcohol-dependent patients. The rationale of the study was based on the relevance of the dopaminergic system for addictive behaviour as well as some preliminary studies. A multi-centre, randomized, double-blind, placebo-controlled, parallel-group study was conducted. A total of 299 detoxified alcohol-dependent patients (ICD-10: F10.2) received either tiapride (300 mg/d) or placebo over a 24-wk study period. Subjects with severe comorbid psychiatric disorder such as schizophrenia or Wernicke-Korsakoff syndrome were excluded. Primary outcome variable was the time to first relapse with relapse defined as any alcohol consumption after detoxification. Data analysis was done with Kaplan-Meier estimates with log-rank test (one-sided, ptest, p=0.9895). Relapse rate was higher in the intervention group (54.4%) than in the control group (40.7%). Like the dopamine antagonist flupenthixol, tiapride was not effective in maintaining alcohol abstinence. Regarding the high success rate in the placebo group the influence of psychosocial treatment in studies investigating drug effects on the course of alcohol dependence has to be considered.
Gopal K Basak; Arunangshu Biswas
2013-02-01
In this paper we show that the continuous version of the self-normalized process $Y_{n,p}(t)=S_n(t)/V_{n,p}+(nt-[nt])X_{[nt]+1}/V_{n,p},0 < t ≤ 1;p>0$ where $S_n(t)=\\sum^{[nt]}_{i=1}X_i$ and $V_{(n,p)}=\\left(\\sum^n_{i=1}|X_i|^p\\right)^{1/p}$ and $X_i i.i.d.$ random variables belong to $DA()$, has a non-trivial distribution $\\mathrm{iff}$ ==2. The case for 2>> and ≤ < 2 is systematically eliminated by showing that either of tightness or finite dimensional convergence to a non-degenerate limiting distribution does not hold. This work is an extension of the work by Csörgő et al. who showed Donsker’s theorem for $Y_{n,2}(\\cdot p)$, i.e., for $p=2$, holds $\\mathrm{iff}$ =2 and identified the limiting process as a standard Brownian motion in sup norm.
Bogh, Morten K B; Schmedes, Anne V; Philipsen, Peter A
2011-01-01
Ultraviolet-B (UV-B) radiation increases serum vitamin D level expressed as 25-hydroxyvitamin D(3) (25(OH)D), but the dose-response relationship and the importance of dose rate is unclear. Of 172 fair-skinned persons screened for 25(OH)D, 55 with insufficient baseline 25(OH)D=50 nm (mean 31.2 nm...... exposed. Skin pigmentation and 25(OH)D were measured before and after the irradiations. The increase in 25(OH)D after UV-B exposure (adjusted for baseline 25(OH)D) was positively correlated with the UV-B dose (P=0.001; R(2) =0.176) but not to dose rate (1-20 min). 25(OH)D increased in response to four UV......) were selected and randomized to one of 11 groups of five participants. Each group was exposed to one of four different UV-B doses: 0.375, 0.75, 1.5 or 3.0 standard erythema dose (SED) for 1, 5, 10 or 20 min. All participants had four UV-B sessions with 2- to 3-day interval with 24% of their skin...
Mönchgesang, Susann; Strehmel, Nadine; Trutschel, Diana; Westphal, Lore; Neumann, Steffen; Scheel, Dierk
2016-01-01
Natural variation of secondary metabolism between different accessions of Arabidopsis thaliana (A. thaliana) has been studied extensively. In this study, we extended the natural variation approach by including biological variability (plant-to-plant variability) and analysed root metabolic patterns as well as their variability between plants and naturally occurring accessions. To screen 19 accessions of A. thaliana, comprehensive non-targeted metabolite profiling of single plant root extracts was performed using ultra performance liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS) and gas chromatography/electron ionization quadrupole mass spectrometry (GC/EI-QMS). Linear mixed models were applied to dissect the total observed variance. All metabolic profiles pointed towards a larger plant-to-plant variability than natural variation between accessions and variance of experimental batches. Ratios of plant-to-plant to total variability were high and distinct for certain secondary metabolites. None of the investigated accessions displayed a specifically high or low biological variability for these substance classes. This study provides recommendations for future natural variation analyses of glucosinolates, flavonoids, and phenylpropanoids and also reference data for additional substance classes. PMID:27649165
Uniform estimate for maximum of randomly weighted sums with applications to insurance risk theory
WANG Dingcheng; SU Chun; ZENG Yong
2005-01-01
This paper obtains the uniform estimate for maximum of sums of independent and heavy-tailed random variables with nonnegative random weights, which can be arbitrarily dependent of each other. Then the applications to ruin probabilities in a discrete time risk model with dependent stochastic returns are considered.
Mason, Barbara J; Crean, Rebecca; Goodell, Vivian; Light, John M; Quello, Susan; Shadan, Farhad; Buffkins, Kimberly; Kyle, Mark; Adusumalli, Murali; Begovic, Adnan; Rao, Santosh
2012-06-01
There are no FDA-approved pharmacotherapies for cannabis dependence. Cannabis is the most widely used illicit drug in the world, and patients seeking treatment for primary cannabis dependence represent 25% of all substance use admissions. We conducted a phase IIa proof-of-concept pilot study to examine the safety and efficacy of a calcium channel/GABA modulating drug, gabapentin, for the treatment of cannabis dependence. A 12-week, randomized, double-blind, placebo-controlled clinical trial was conducted in 50 unpaid treatment-seeking male and female outpatients, aged 18-65 years, diagnosed with current cannabis dependence. Subjects received either gabapentin (1200 mg/day) or matched placebo. Manual-guided, abstinence-oriented individual counseling was provided weekly to all participants. Cannabis use was measured by weekly urine toxicology and by self-report using the Timeline Followback Interview. Cannabis withdrawal symptoms were assessed using the Marijuana Withdrawal Checklist. Executive function was measured using subtests from the Delis-Kaplan Executive Function System. Relative to placebo, gabapentin significantly reduced cannabis use as measured both by urine toxicology (p=0.001) and by the Timeline Followback Interview (p=0.004), and significantly decreased withdrawal symptoms as measured by the Marijuana Withdrawal Checklist (pGabapentin was also associated with significantly greater improvement in overall performance on tests of executive function (p=0.029). This POC pilot study provides preliminary support for the safety and efficacy of gabapentin for treatment of cannabis dependence that merits further study, and provides an alternative conceptual framework for treatment of addiction aimed at restoring homeostasis in brain stress systems that are dysregulated in drug dependence and withdrawal.
Tapiero, Charles S.; Vallois, Pierre
2016-11-01
The premise of this paper is that a fractional probability distribution is based on fractional operators and the fractional (Hurst) index used that alters the classical setting of random variables. For example, a random variable defined by its density function might not have a fractional density function defined in its conventional sense. Practically, it implies that a distribution's granularity defined by a fractional kernel may have properties that differ due to the fractional index used and the fractional calculus applied to define it. The purpose of this paper is to consider an application of fractional calculus to define the fractional density function of a random variable. In addition, we provide and prove a number of results, defining the functional forms of these distributions as well as their existence. In particular, we define fractional probability distributions for increasing and decreasing functions that are right continuous. Examples are used to motivate the usefulness of a statistical approach to fractional calculus and its application to economic and financial problems. In conclusion, this paper is a preliminary attempt to construct statistical fractional models. Due to the breadth and the extent of such problems, this paper may be considered as an initial attempt to do so.
M.Y. Malik
2014-06-01
Full Text Available The present work concerns the pressure dependent viscosity in Carreau fluid through porous medium. Four different combinations of pressure dependent viscosity and pressure dependent porous medium parameters are considered for two types of flow situations namely (i Poiseuille flow and (ii Couette flow. The solutions of non-linear equations have been evaluated numerically by Shooting method along with Runge-Kutta Fehlberg method. The physical features of pertinent parameters have been discussed through graphs.
Coll-de-Tuero Gabriel
2012-08-01
Full Text Available Abstract Background Kidney disease is associated with an increased total mortality and cardiovascular morbimortality in the general population and in patients with Type 2 diabetes. The aim of this study is to determine the prevalence of kidney disease and different types of renal disease in patients with type 2 diabetes (T2DM. Methods Cross-sectional study in a random sample of 2,642 T2DM patients cared for in primary care during 2007. Studied variables: demographic and clinical characteristics, pharmacological treatments and T2DM complications (diabetic foot, retinopathy, coronary heart disease and stroke. Variables of renal function were defined as follows: 1 Microalbuminuria: albumin excretion rate & 30 mg/g or 3.5 mg/mmol, 2 Macroalbuminuria: albumin excretion rate & 300 mg/g or 35 mg/mmol, 3 Kidney disease (KD: glomerular filtration rate according to Modification of Diet in Renal Disease 2 and/or the presence of albuminuria, 4 Renal impairment (RI: glomerular filtration rate 2, 5 Nonalbuminuric RI: glomerular filtration rate 2 without albuminuria and, 5 Diabetic nephropathy (DN: macroalbuminuria or microalbuminuria plus diabetic retinopathy. Results The prevalence of different types of renal disease in patients was: 34.1% KD, 22.9% RI, 19.5% albuminuria and 16.4% diabetic nephropathy (DN. The prevalence of albuminuria without RI (13.5% and nonalbuminuric RI (14.7% was similar. After adjusting per age, BMI, cholesterol, blood pressure and macrovascular disease, RI was significantly associated with the female gender (OR 2.20; CI 95% 1.86–2.59, microvascular disease (OR 2.14; CI 95% 1.8–2.54 and insulin treatment (OR 1.82; CI 95% 1.39–2.38, and inversely associated with HbA1c (OR 0.85 for every 1% increase; CI 95% 0.80–0.91. Albuminuria without RI was inversely associated with the female gender (OR 0.27; CI 95% 0.21–0.35, duration of diabetes (OR 0.94 per year; CI 95% 0.91–0.97 and directly associated with HbA1c (OR 1.19 for every
Wu, Li-Tzy; Pan, Jeng-Jong; Blazer, Dan G; Tai, Betty; Stitzer, Maxine L; Woody, George E
2010-06-01
This study applies a latent variable approach to examine gender and racial/ethnic differences in cocaine dependence, to determine the presence of differential item functioning (DIF) or item-response bias to diagnostic questions of cocaine dependence, and to explore the effects of DIF on the predictor analysis of cocaine dependence. The analysis sample included 682 cocaine users enrolled in two national multisite studies of the National Drug Abuse Treatment Clinical Trials Network (CTN). Participants were recruited from 14 community-based substance abuse treatment programs associated with the CTN, including 6 methadone and 8 outpatient nonmethadone programs. Factor and multiple indicators-multiple causes (MIMIC) procedures evaluated the latent continuum of cocaine dependence and its correlates. MIMIC analysis showed that men exhibited lower odds of cocaine dependence than women (regression coefficient, beta = -0.34), controlling for the effects of DIF, years of cocaine use, addiction treatment history, comorbid drug dependence diagnoses, and treatment setting. There were no racial/ethnic differences in cocaine dependence; however, DIF by race/ethnicity was noted. Within the context of multiple community-based addiction treatment settings, women were more likely than men to exhibit cocaine dependence. Addiction treatment research needs to further evaluate gender-related differences in drug dependence in treatment entry and to investigate how these differences may affect study participation, retention, and treatment response to better serve this population.
Oliveto, Alison; Poling, James; Mancino, Michael J.; Feldman, Zachary; Cubells, Joseph F.; Pruzinsky, Rhonda; Gonsai, Kishorchandra; Cargile, Christopher; Sofuoglu, Mehmet; Chopra, Mohit P.; Gonzalez-Haddad, Gerardo; Carroll, Kathleen M.; Kosten, Thomas R.
2010-01-01
This study examined the dose-related efficacy of disulfiram for treating cocaine dependence in methadone-stabilized cocaine dependent participants. Design One hundred sixty-one cocaine-and opioid-dependent volunteers were entered into a 14-week, double blind, randomized, placebo-controlled clinical trial at two sites. Methods Participants were stabilized on methadone during weeks 1–2 and received disulfiram at 0, 62.5, 125 or 250 mg/day during weeks 3–14. All participants also received weekly cognitive behavioral therapy. Thrice-weekly urine samples and weekly self-reported drug use assessments were obtained. Results Baseline subject characteristics, retention and drug use did not differ across groups. Outcome analyses were performed on those who participated beyond week 2. Opioid positive urine samples and self-reported opioid use did not differ by treatment group. The prevalence of alcohol use was low prior to and during the trial and did not differ by treatment group. Cocaine-positive urines increased over time in the 62.5 and 125 mg disulfiram groups and decreased over time in the 250 mg disulfiram and placebo groups (p<0.0001). Self-reported cocaine use increased in the 125 mg disulfiram group relative to the other three treatment groups (p=0.04). Conclusions Disulfiram may be contraindicated for cocaine dependence at doses less than 250 mg/day. Whether disulfiram at higher doses is efficacious in reducing cocaine use in dually cocaine and opioid dependent individuals needs to be determined. PMID:20828943
Otto, Michael W; Hearon, Bridget A; McHugh, R Kathryn; Calkins, Amanda W; Pratt, Elizabeth; Murray, Heather W; Safren, Steven A; Pollack, Mark H
2014-01-01
Many patients diagnosed with opioid dependence do not adequately respond to pharmacologic, psychosocial, or combination treatment, highlighting the importance of novel treatment strategies for this population. The current study examined the efficacy of a novel behavioral treatment focusing on internal cues for drug use (Cognitive Behavioral Therapy for Interoceptive Cues; CBT-IC) relative to an active comparison condition, Individual Drug Counseling (IDC), when added to methadone maintenance treatment (MMT) among those who had not responded to MMT. Participants (N=78) were randomly assigned to receive 15 sessions of CBT-IC or IDC as an adjunct to ongoing MMT and counseling. Oral toxicology screens were the primary outcome. Results indicated no treatment differences between CBT-IC and IDC and a small, significant reduction of self-reported drug use, but no change on toxicology screens. Tests of potential moderators, including sex, anxiety sensitivity, and coping motives for drug use, did not yield significant interactions. Among opioid-dependent outpatients who have not responded to MMT and counseling, the addition of IDC or CBT-IC did not result in additive outcome benefits. These results highlight the need for more potent treatment strategies for opioid dependence, particularly among those who do not fully respond to frontline treatment.
Peng, Degao; van Aggelen, Helen; Steinmann, Stephan; Yang, Yang; Yang, Weitao; Duke University Team
2014-03-01
The particle-particle random-phase approximation (pp-RPA) recently attracts extensive interests in quantum chemistry recently. Pp-RPA is a versatile model to calculate ground-state correlation energies, and double ionization potential/double electron affinity. We inspect particle-particle random-phase approximation in different perspectives to further understand its theoretical fundamentals. Viewed as summation of all ladder diagrams, the pp-RPA correlation energy is proved to be analytically equivalent to the ladder coupled-cluster doubles (ladder-CCD) theory. With this equivalence, we can make use of various well-established coupled-cluster techniques to study pp-RPA. Furthermore, we establish linear-response time-dependent density-functional theory with pairing fields (TDDFT-PF), where pp-RPA can be interpreted as the mean-field approximation to a general theory. TDDFT-PF is closely related to the density-functional theory of superconductors, but is applied to normal systems to capture exact N plus/minus 2 excitations. In the linear-response regime, both the adiabatic and non-adiabatic TDDFT-PF equations are established. This sets the fundamentals for further density-functional developments aiming for pp-RPA. These theoretical perspectives will be very helpful for future study.
Taher, Ali T; Porter, John; Viprakasit, Vip; Kattamis, Antonis; Chuncharunee, Suporn; Sutcharitchan, Pranee; Siritanaratkul, Noppadol; Galanello, Renzo; Karakas, Zeynep; Lawniczek, Tomasz; Ros, Jacqueline; Zhang, Yiyun; Habr, Dany; Cappellini, Maria Domenica
2012-08-02
Nontransfusion-dependent thalassemia (NTDT) patients may develop iron overload and its associated complications despite receiving only occasional or no transfusions. The present 1-year, randomized, double-blind, placebo-controlled THALASSA (Assessment of Exjade in Nontransfusion-Dependent Thalassemia) trial assessed the efficacy and safety of deferasirox in iron-overloaded NTDT patients. A total of 166 patients were randomized in a 2:1:2:1 ratio to starting doses of 5 or 10 mg/kg/d of deferasirox or placebo. The means ± SD of the actual deferasirox doses received over the duration of the study in the 5 and 10 mg/kg/d starting dose cohorts were 5.7 ± 1.4 and 11.5 ± 2.9 mg/kg/d, respectively. At 1 year, the liver iron concentration (LIC) decreased significantly compared with placebo (least-squares mean [LSM] ± SEM, -2.33 ± 0.7 mg Fe/g dry weight [dw], P = .001, and -4.18 ± 0.69 mg Fe/g dw, P deferasirox groups, respectively (baseline values [means ± SD], 13.11 ± 7.29 and 14.56 ± 7.92 mg Fe/g dw, respectively). Similarly, serum ferritin decreased significantly compared with placebo by LSM -235 and -337 ng/mL for the deferasirox 5 and 10 mg/kg/d groups, respectively (P deferasirox significantly reduces iron overload in NTDT patients with a frequency of overall adverse events similar to placebo.
Brissette Suzanne
2011-07-01
Full Text Available Abstract Background Substitution with opioid-agonists (e.g., methadone has shown to be an effective treatment for chronic long-term opioid dependency. Patient satisfaction with treatment has been associated with improved addiction treatment outcomes. However, there is a paucity of studies evaluating patients' satisfaction with Opioid Substitution Treatment (OST. In the present study, participants' satisfaction with OST was evaluated at 3 and 12 months. We sought to test the relationship between satisfaction and patients' characteristics, the treatment modality received and treatment outcomes. Methods Data from a randomized controlled trial, the North American Opiate Medication Initiative (NAOMI, conducted in Vancouver and Montreal (Canada between 2005-2008, was analyzed. The NAOMI study compared the effectiveness of oral methadone vs. injectable diacetylmorphine over 12 months. A small sub-group of patients received injectable hydromorphone on a double blind basis with diacetylmorphine. The Client Satisfaction Questionnaire (CSQ-8 was used to measure satisfaction with treatment. CSQ-8 scores, as well as retention and response to treatment, did not differ between those receiving hydromorphone and diacetylmorphine at 3 or 12 months assessments; therefore, these two groups were analyzed together as the 'injectable' treatment group. Results A total of 232 (92% and 237 (94% participants completed the CSQ-8 at 3 and 12 months, respectively. Participants in both groups were highly satisfied with treatment. Independent of treatment group, participants satisfied with treatment at 3 months were more likely to be retained at 12 months. Multivariate analysis indicated that satisfaction was greater among those randomized to the injection group after controlling for treatment effectiveness. Participants who were retained, responded to treatment, and had fewer psychological symptoms were more satisfied with treatment. Finally, open-ended comments were made by
Wills, C; Miller, C
1976-02-01
It is shown, through theory and computer simulations of outbreeding Mendelian populations, that there may be conditions under which a balance is struck between two facotrs. The first is the advantage of random assortment, which will, when multilocus selection is for intermediate equilibrium values, lead to higher average heterozygosity than when linkage is introduced. There is some indication that random assortment is also advantageous when selection is toward a uniform distribution of equilibrium values. The second factor is the advantage of linkage between loci having positive epistatic interactions. When multilocus selection is for a bimodal distribution of equilibrium values an early advantage of random assortment is replaced by a later disadvantage. Linkage disequilibrium, which in finite populations is increased only by random or selective sampling, may hinder the movement of alleles to their selective equilibria, thus leading to the advantage of random assortment.-Some consequences of this approach to the structure of natural populations are discussed.
Novikov, V V; Sheĭman, I M; Lisitsyn, A S; Kliubin, A V; Fesenko, E E
2002-01-01
It was shown that the stimulating effect of weak combined magnetic fields (constant component 42 microT, frequency of the variable component 3.7 Hz) on the division of planarians depends on the amplitude of the variable component of the field. The effect is particularly pronounced at 40 (the main maximum), 120, 160, and 640 nT. Narrow ranges of effective amplitudes alternate in some cases with equally narrow ranges in which the system does not respond to he treatment. In the range of super weak amplitudes of the variable field (0.1 and 1 nT), the stimulating effect is poorly pronounced. The data obtained indicate the presence of narrow amplitude windows in the response of the biological systems to weak and super weak magnetic fields. In a special series of experiments, it was shown that the effect of fields on planarians is partially mediated via aqueous medium preliminarily treated with weak magnetic fields. It is noteworthy that in experiments with water treated with weak magnetic fields, there were no pronounced maxima and minima in the magnitude of the effect in the range of amplitude of the variable magnetic field from 40 to 320 nT.
Jackson, B Scott
2004-10-01
Many different types of integrate-and-fire models have been designed in order to explain how it is possible for a cortical neuron to integrate over many independent inputs while still producing highly variable spike trains. Within this context, the variability of spike trains has been almost exclusively measured using the coefficient of variation of interspike intervals. However, another important statistical property that has been found in cortical spike trains and is closely associated with their high firing variability is long-range dependence. We investigate the conditions, if any, under which such models produce output spike trains with both interspike-interval variability and long-range dependence similar to those that have previously been measured from actual cortical neurons. We first show analytically that a large class of high-variability integrate-and-fire models is incapable of producing such outputs based on the fact that their output spike trains are always mathematically equivalent to renewal processes. This class of models subsumes a majority of previously published models, including those that use excitation-inhibition balance, correlated inputs, partial reset, or nonlinear leakage to produce outputs with high variability. Next, we study integrate-and-fire models that have (nonPoissonian) renewal point process inputs instead of the Poisson point process inputs used in the preceding class of models. The confluence of our analytical and simulation results implies that the renewal-input model is capable of producing high variability and long-range dependence comparable to that seen in spike trains recorded from cortical neurons, but only if the interspike intervals of the inputs have infinite variance, a physiologically unrealistic condition. Finally, we suggest a new integrate-and-fire model that does not suffer any of the previously mentioned shortcomings. By analyzing simulation results for this model, we show that it is capable of producing output
Majdak Marek
2017-01-01
Full Text Available The objective of this paper was to determine the relationship between the efficiency of photovoltaic panels and the value of the angle of their inclination relative to the horizon. For the purpose of experimental research have been done tests on the photovoltaic modules made of monocrystalline, polycrystalline and amorphous silicon. The experiment consisted of measurement of the voltage and current generated by photovoltaic panels at a known value of solar radiation and a specified resistance value determined by using resistor with variable value of resistance and known value of the angle of their inclination relative to the horizon.
Tošić, Tamara; Sellers, Kristin K; Fröhlich, Flavio; Fedotenkova, Mariia; Beim Graben, Peter; Hutt, Axel
2015-01-01
For decades, research in neuroscience has supported the hypothesis that brain dynamics exhibits recurrent metastable states connected by transients, which together encode fundamental neural information processing. To understand the system's dynamics it is important to detect such recurrence domains, but it is challenging to extract them from experimental neuroscience datasets due to the large trial-to-trial variability. The proposed methodology extracts recurrent metastable states in univariate time series by transforming datasets into their time-frequency representations and computing recurrence plots based on instantaneous spectral power values in various frequency bands. Additionally, a new statistical inference analysis compares different trial recurrence plots with corresponding surrogates to obtain statistically significant recurrent structures. This combination of methods is validated by applying it to two artificial datasets. In a final study of visually-evoked Local Field Potentials in partially anesthetized ferrets, the methodology is able to reveal recurrence structures of neural responses with trial-to-trial variability. Focusing on different frequency bands, the δ-band activity is much less recurrent than α-band activity. Moreover, α-activity is susceptible to pre-stimuli, while δ-activity is much less sensitive to pre-stimuli. This difference in recurrence structures in different frequency bands indicates diverse underlying information processing steps in the brain.
高峰; 刘绪庆
2012-01-01
We mainly aim to study the bivariate continuous random variables that take positive values by virtue of the point-set function proposed by Feller and the notion of the bivariate copula.A new method of calculating the distributions of sum,product and quotient for the random variables is derived.Finally,we apply the method to a practical example.%应用Feller提出的点-集函数并结合二元copula,对二元连续型正值随机变量的和、积、商的分布进行了研究,得到了和、积、商分布的一种新的计算方法.最后给出一个应用实例.
Price, Kimber L; DeSantis, Stacia M; Simpson, Annie N; Tolliver, Bryan K; McRae-Clark, Aimee L; Saladin, Michael E; Baker, Nathaniel L; Wagner, Mark T; Brady, Kathleen T
2011-01-01
Inconsistencies in reports on methamphetamine (METH) associated cognitive dysfunction may be attributed, at least in part, to the diversity of study sample features (eg, clinical and demographic characteristics). The current study assessed cognitive function in a METH-dependent population from rural South Carolina, and the impact of demographic and clinical characteristics on performance. Seventy-one male (28.2%) and female (71.8%) METH-dependent subjects were administered a battery of neurocognitive tests including the Test of Memory Malingering (TOMM), Shipley Institute of Living Scale, Paced Auditory Serial Addition Test (PASAT), Symbol Digit Modalities Test (SDMT), Grooved Pegboard Test, California Verbal Learning Test (CVLT), and Wisconsin Card Sorting Test (WCST). Demographic and clinical characteristics (eg, gender, frequency of METH use) were examined as predictors of performance. Subjects scored significantly lower than expected on one test of attention and one of fine motor function, but performed adequately on all other tests. There were no predictors of performance on attention; however, more frequent METH use was associated with better performance for males and worse for females on fine motor skills. The METH-dependent individuals in this population exhibit very limited cognitive impairment. The marked differences in education, Intellectual Quotient (IQ), and gender in our sample when compared to the published literature may contribute to these findings. Characterization of the impact of clinical and/or demographic features on cognitive deficits could be important in guiding the development of treatment interventions.
Babonneix, A.; Gourdeau, L.; Durand, F.; Menkes, C. E.; Djath, N.
2012-04-01
As the most powerful source of climatic variability in the Pacific Ocean, the El Niño Southern Oscillation (ENSO) deeply impacts the equatorial oceanic currents. The Pacific Equatorial UnderCurrent (EUC) is a powerful jet flowing eastward and shoaling with the thermocline in the eastern Pacific, bringing cold waters in surface that retroact with the atmosphere. Its transport has thus been found to follow significant variations at ENSO timescale, with an increased (decreased) transport in La Niña (El Niño) phases. However, the EUC mean properties also vary more slowly due to extratropical forcing. This process is able to modify the heat and mass transports of the subducted waters that feed the EUC. By changing the mean equatorial oceanic conditions, this is suspected to modulate in return the ENSO signal. The EUC sources have very different origins: contributions come from both hemispheres, in part from the Low-Latitude Western Boundary Currents (LLWBCs) and the remaining from the interior ocean. Each source follows different pathways and is characterized by particular properties which differently influences the properties of the downstream equatorial undercurrent and the cold tongue upwelling. The question of the location of the different EUC sources is thus of crucial importance. In this poster, we investigate the links between the ENSO variability and the partitioning of the EUC sources. For this purpose, we use a set of five simulations made available by the DRAKKAR project ranging from a 2° laminar resolution to a turbulent 1/12° partly resolving the meso-scale processes. Increasing models horizontal resolution is largely thought to improve the quality of the resulting simulated currents, in terms of dynamics as of variability. Results show that if some distinct elements appear in terms of mean transit times, little variations are found in terms of partitioning within the different simulations. However, we show that the partitioning between the EUC sources
谭希丽; 王淼
2014-01-01
应用ρ-混合随机变量序列截断法、Hölder 不等式、Markov 不等式、Jensen 不等式、Cr不等式及ρ-混合随机变量的Rosenthal型矩不等式，考察在没有同分布假设条件下，ρ-混合随机变量序列加权和的完全收敛性质，并利用 Borel-Cantelli 引理，给出ρ-混合随机变量序列加权和的Marcinkiewicz-Zygmund型强大数定律。%The authors studied the complete convergence for weighted sums ofρ--mixing random variables sequence without assumption of identical distribution via truncation method forρ--mixing random variables sequence,Hölder inequality,Markov inequality,Jensen inequality,Cr inequality, moment inequality and Rosenthal inequality.As an example of application,we further extended the Marcinkiewicz-Zygmund type strong law of large numbers for weighted sums ofρ--mixing random variables sequence with the aid of Borel-Cantelli lemma.
Carrillo, Catherine D; Plante, Daniel; Iugovaz, Irène; Kenwell, Robyn; Bélanger, Ghislaine; Boucher, Francine; Poulin, Nathalie; Trottier, Yvon-Louis
2014-10-01
Campylobacter is the most frequent cause of bacterial gastroenteritis in Canada, and the illness is commonly associated with poultry consumption. Whereas Canadian retail poultry is often contaminated with campylobacters, studies on the prevalence of this organism are inconsistent due to variability in sampling and microbiological methodology. To determine the current microbiological status of Canadian poultry, and to evaluate two commonly used microbiological methods, 348 raw poultry samples were collected at retail across Canada over a period of 3 years (2007 to 2010) and were analyzed for the presence of thermophilic Campylobacter species. The overall prevalence of Campylobacter spp. was found to be 42.8% by a combination of the two testing methods, with 33.9% of the samples positive for C. jejuni, 3.7% of the samples positive for C. coli, and 5.2% of the samples positive for both. Variability in Campylobacter spp. prevalence was observed in samples obtained from different regions across Canada and from poultry with or without skin, but this was not statistically significant. In co-contaminated samples, C. jejuni was preferentially recovered from Preston agar compared with mCCDA and Campy-Cefex agar, with an increase in recovery of C. coli on all selective media after 48 h of enrichment. A subset of 214 of the poultry rinses were analyzed by both Health Canada's standard method, MFLP-46 (enrichment in Park and Sanders broth), and a second method requiring enrichment in Bolton broth. Significantly more positive samples were obtained with the MFLP-46 method (40.6%) than with the alternate method (35.0%). This improved recovery with MFLP-46 may be due to the omission of cycloheximide from this method. These results demonstrate that determination of prevalence of Campylobacter spp. on poultry products may be significantly impacted by the choice of microbiological methods used. Canadian poultry continues to be a source of exposure to Campylobacter spp.
Two-Stage Modelling Of Random Phenomena
Barańska, Anna
2015-12-01
The main objective of this publication was to present a two-stage algorithm of modelling random phenomena, based on multidimensional function modelling, on the example of modelling the real estate market for the purpose of real estate valuation and estimation of model parameters of foundations vertical displacements. The first stage of the presented algorithm includes a selection of a suitable form of the function model. In the classical algorithms, based on function modelling, prediction of the dependent variable is its value obtained directly from the model. The better the model reflects a relationship between the independent variables and their effect on the dependent variable, the more reliable is the model value. In this paper, an algorithm has been proposed which comprises adjustment of the value obtained from the model with a random correction determined from the residuals of the model for these cases which, in a separate analysis, were considered to be the most similar to the object for which we want to model the dependent variable. The effect of applying the developed quantitative procedures for calculating the corrections and qualitative methods to assess the similarity on the final outcome of the prediction and its accuracy, was examined by statistical methods, mainly using appropriate parametric tests of significance. The idea of the presented algorithm has been designed so as to approximate the value of the dependent variable of the studied phenomenon to its value in reality and, at the same time, to have it "smoothed out" by a well fitted modelling function.
Barbosa, Graziela Murta; Colombo, Andrea Vieira; Rodrigues, Paulo Henrique; Simionato, Maria Regina Lorenzetti
2015-01-01
It is well known that strain and virulence diversity exist within the population structure of Porphyromonas gingivalis. In the present study we investigate intra- and inter-species variability in biofilm formation of Porphyromonas gingivalis and partners Prevotella intermedia and Prevotella nigrescens. All strains tested showed similar hydrophobicity, except for P. gingivalis W83 which has roughly half of the hydrophobicity of P. gingivalis ATCC33277. An intraspecies variability in coaggregation of P. gingivalis with P. intermedia was also found. The association P. gingivalis W83/P. intermedia 17 produced the thickest biofilm and strain 17 was prevalent. In a two-compartment system P. gingivalis W83 stimulates an increase in biomass of strain 17 and the latter did not stimulate the growth of P. gingivalis W83. In addition, P. gingivalis W83 also stimulates the growth of P. intermedia ATCC25611 although strain W83 was prevalent in the association with P. intermedia ATCC25611. P. gingivalis ATCC33277 was prevalent in both associations with P. intermedia and both strains of P. intermedia stimulate the growth of P. gingivalis ATCC33277. FISH images also showed variability in biofilm structure. Thus, the outcome of the association P. gingivalis/P. intermedia seems to be strain-dependent, and both soluble factors and physical contact are relevant. The association P. gingivalis-P. nigrescens ATCC33563 produced larger biomass than each monotypic biofilm, and P. gingivalis was favored in consortia, while no differences were found in the two-compartment system. Therefore, in consortia P. gingivalis-P. nigrescens physical contact seems to favor P. gingivalis growth. The intraspecies variability found in our study suggests strain-dependence in ability of microorganisms to recognize molecules in other bacteria which may further elucidate the dysbiosis event during periodontitis development giving additional explanation for periodontal bacteria, such as P. gingivalis and P
Sghaier T
2016-10-01
Full Text Available The objective of this study was to evaluate the effectiveness of both Normal and two-parameter Weibull distributions in describing diameter distribution of Tetraclinis articulata stands in north-east Tunisia. The parameters of the Weibull function were estimated using the moments method and maximum likelihood approaches. The data used in this study came from temporary plots. The three diameter distribution models were compared firstly by estimating the parameters of the distribution directly from individual tree measurements taken in each plot (parameter estimation method, and secondly by predicting the same parameters from stand variables (parameter prediction method. The comparison was based on bias, mean absolute error, mean square error and the Reynolds’ index error (as a percentage. On the basis of the parameter estimation method, the Normal distribution gave slightly better results, whereas the Weibull distribution with the maximum likelihood approach gave the best results for the parameter prediction method. Hence, in the latter case, the Weibull distribution with the maximum likelihood approach appears to be the most suitable to estimate the parameters for reducing the different comparison criteria for the distribution of trees by diameter class in Tetraclinis articulata forests in Tunisia.
Sigmund, Eric E.; Novikov, Dmitry S.; Sui, Dabang; Ukpebor, Obehi; Baete, Steven; Babb, James S.; Liu, Kecheng; Feiweier, Thorsten; Kwon, Jane; Mcgorty, KellyAnne; Bencardino, Jenny; Fieremans, Els
2014-01-01
Purpose To collect diffusion tensor imaging (DTI) at multiple diffusion times Td in skeletal muscle in normal subjects and chronic exertional compartment syndrome (CECS) patients and analyze the data with the random permeable barrier model (RPBM) for biophysical specificity. Materials and Methods Using an IRB-approved HIPAA-compliant protocol, seven patients with clinical suspicion of CECS and eight healthy volunteers underwent DTI of the calf muscle in a Siemens MAGNETOM Verio 3-T scanner at rest and after treadmill exertion at 4 different diffusion times. Radial diffusion values λrad were computed for each of 7 different muscle compartments and analyzed with RPBM to produce estimates of free diffusivity D0, fiber diameter a, and permeability κ. Fiber diameter estimates were compared with measurements from literature autopsy reference for several compartments. Response factors (post/pre-exercise ratios) were computed and compared between normal controls and CECS patients using a mixed-model two-way analysis of variance. Results All subjects and muscle compartments showed nearly time-independent diffusion along and strongly time-dependent diffusion transverse to the muscle fibers. RPBM estimates of fiber diameter correlated well with corresponding autopsy reference. D0 showed significant (p<0.05) increases with exercise for volunteers, and a increased significantly (p<0.05) in volunteers. At the group level, response factors of all three parameters showed trends differentiating controls from CECS patients, with patients showing smaller diameter changes (p=0.07), and larger permeability increases (p=0.07) than controls. Conclusions Time-dependent diffusion measurements combined with appropriate tissue modeling can provide enhanced microstructural specificity for in vivo tissue characterization. In CECS patients, our results suggest that high-pressure interfiber edema elevates free diffusion and restricts exercise-induced fiber dilation. Such specificity may be
B. Bonakdarpour
2015-01-01
Full Text Available Although fMRI is increasingly used to assess language-related brain activation in patients with aphasia, few studies have examined the hemodynamic response function (HRF in perilesional, and contralesional areas of the brain. In addition, the relationship between HRF abnormalities and other variables such as lesion size and severity of aphasia has not been explored. The objective of this study was to investigate changes in HRF signal during language-related neural activation in patients with stroke-induced aphasia (SA. We also examined the status of the HRF in patients with aphasia due to nonvascular etiology, namely, primary progressive aphasia (PPA. Five right handed SA patients, three PPA patients, and five healthy individuals participated in the study. Structural damage was quantified with T1-weighted MR images. Functional MR imaging was performed with long trial event-related design and an overt naming task to measure BOLD signal time to peak (TTP and percent signal change (ΔS. In SA patients, the average HRF TTP was significantly delayed in the left hemisphere regions involved in naming compared to healthy participants and PPA patients. However, ΔS was not different in SA patients compared to the other two groups. Delay in HRF TTP in the left hemisphere naming network of SA patients was correlated with lesion size and showed a negative correlation with global language function. There were no significant differences in the HRF TTP and ΔS in the right hemisphere homologues of the naming network or in the left and the right occipital control regions across the three groups. In PPA patients, HRF had a normal pattern. Our results indicate that abnormal task-related HRF is primarily found in the left hemisphere language network of SA patients and raise the possibility that abnormal physiology superimposed on structural damage may contribute to the clinical deficit. Follow-up investigations in a larger sample of age-matched healthy individuals
Kristin Brekke
Full Text Available Vacc-4x, a Gag p24-based therapeutic HIV vaccine, has been shown to reduce viral load set-points after intradermal administration. In this randomized controlled pilot study we investigate intranasal administration of Vacc-4x with Endocine as adjuvant.Safety and immunogenicity were tested in patients on effective ART. They were randomized to low, medium or high dose Vacc-4x or adjuvant alone, administered four times at weekly intervals with no booster. Vacc-4x-specific T cell responses were measured in vitro by proliferation and in vivo by a single DTH skin test at the end of study. Nasal and rectal mucosal secretions were analyzed for Vacc-4x-specific antibodies by ELISA. Immune regulation induced by Vacc-4x was assessed by functional blockade of the regulatory cytokines IL-10 and TGF-β.Vacc-4x proliferative T cell responses increased only among the vaccinated (p ≤ 0.031. The low dose group showed the greatest increase in Vacc-4x CD8+T cell responses (p = 0.037 and developed larger DTH (p = 0.005 than the adjuvant group. Rectal (distal Vacc-4x IgA and IgG antibodies also increased (p = 0.043 in this group. In contrast, the high dose generated higher nasal (local Vacc-4x IgA (p = 0.028 and serum IgG (p = 0.030 antibodies than the adjuvant. Irrespective of dose, increased Vacc-4x CD4+T cell responses were associated with low proliferation (r = -0.82, p < 0.001 and high regulation (r = 0.61, p = 0.010 at baseline.Intranasal administration of Vacc-4x with Endocine was safe and induced dose-dependent vaccine-specific T cell responses and both mucosal and systemic humoral responses. The clinical significance of dose, immune regulation and mucosal immunity warrants further investigation.ClinicalTrials.gov NCT01473810.
Hung, T; Jones, D O; Kirshner, R P; Chornock, R; Berger, E; Rest, A; Huber, M; Narayan, G; Scolnic, D; Waters, C; Wainscoat, R; Martin, D C; Forster, K; Neill, J D
2016-01-01
We analyze the wavelength-dependent variability of a sample of spectroscopically confirmed active galactic nuclei (AGN) selected from near-UV ($NUV$) variable sources in the GALEX Time Domain Survey that have a large amplitude of optical variability (difference-flux S/N $>$ 3) in the Pan-STARRS1 Medium Deep Survey (PS1 MDS). By matching GALEX and PS1 epochs in 5 bands ($NUV$, $g_{P1}$, $r_{P1}$, $i_{P1}$, $z_{P1}$) in time, and taking their flux difference, we create co-temporal difference-flux spectral energy distributions ($\\Delta f$SEDs) using two chosen epochs for each of the 23 objects in our sample on timescales of about a year. We confirm the "bluer-when-brighter" trend reported in previous studies, and measure a median spectral index of the $\\Delta f$SEDs of $\\alpha_{\\lambda}$ = 2.1 that is consistent with an accretion disk spectrum. We further fit the $\\Delta f$SEDs of each source with a standard accretion disk model in which the accretion rate changes from one epoch to the other. In our sample, 17 o...
El-Bary, Ahmed Abd; Aboelwafa, Ahmed A; Al Sharabi, Ibrahim M
2012-03-01
The aim of this work was to understand the influence of different formulation variables on the optimization of pH-dependent, colon-targeted, sustained-release mesalamine microspheres prepared by O/O emulsion solvent evaporation method, employing pH-dependent Eudragit S and hydrophobic pH-independent ethylcellulose polymers. Formulation variables studied included concentration of Eudragit S in the internal phase and the ratios between; internal to external phase, drug to Eudragit S and Eudragit S to ethylcellulose to mesalamine. Prepared microspheres were evaluated by carrying out in vitro release studies and determination of particle size, production yield, and encapsulation efficiency. In addition, morphology of microspheres was examined using optical and scanning electron microscopy. Emulsion solvent evaporation method was found to be sensitive to the studied formulation variables. Particle size and encapsulation efficiency increased by increasing Eudragit S concentration in the internal phase, ratio of internal to external phase, and ratio of Eudragit S to the drug. Employing Eudragit S alone in preparation of the microspheres is only successful in forming acid-resistant microspheres with pulsatile release pattern at high pH. Eudragit S and ethylcellulose blend microspheres were able to control release under acidic condition and to extend drug release at high pH. The stability studies carried out at 40°C/75% RH for 6 months proved the stability of the optimized formulation. From the results of this investigation, microencapsulation of mesalamine in microspheres using blend of Eudragit S and ethylcellulose could constitute a promising approach for site-specific and controlled delivery of drug in colon.
O'Bryant, Amber J; Allred, Rachel P; Maldonado, Monica A; Cormack, Lawrence K; Jones, Theresa A
2011-10-10
Reaching tasks are popular tools for investigating the neural mechanisms of motor skill learning and recovery from brain damage in rodents, but there is considerable unexplained variability across studies using these tasks. We investigated whether breeder, batch effects, experimenter, time of year, weight and other factors contribute to differences in the acquisition and performance of a skilled reaching task, the single pellet retrieval task, in adult male Long-Evans hooded rats. First, we retrospectively analyzed task acquisition and performance in rats from different breeding colonies that were used in several studies spanning a 3 year period in our laboratory. Second, we compared reaching variables in age-matched rats from different breeders that were trained together as a batch by the same experimenters. All rats had received daily training on the reaching task until they reached a criterion of successful reaches per attempt. We found significant breeder-dependent differences in learning rate and final performance level. This was found even when age-matched rats from different breeders were trained together by the same experimenters. There was also significant batch-to-batch variability within rats from the same breeder trained by the same experimenter. Other factors, including weight, paw preference and the experimenter, were not as strong or consistent in their contributions to differences across studies. The breeder and batch effects found within the same rat strain may reflect genetic and environmental influences on the neural substrates of motor skill learning. This is an important consideration when comparing baseline performance across studies and for controlling variability within studies.
Complete Convergence of Series of Dependent Random Variables%相依随机变量序列的完全收敛性
张振荣; 孙国红
2010-01-01
Hus和Robbin于1947年提出了完全收敛性的概念,完全收敛比几乎处处收敛条件更严格.本文通过构造收敛鞅,证明了相依随机变量序列的完全收敛性.作为推论,证明了负相依随机变量序列的完全收敛性.
Revicki, D.A.; Brandenburg, N.A.; Muus, P.; Yu, R.; Knight, R.; Fenaux, P.
2013-01-01
We report health-related quality of life (HRQL) outcomes assessed using the Functional Assessment of Cancer Therapy-Anemia (FACT-An) among 167 RBC transfusion-dependent patients with IPSS Low-/Intermediate-1-risk del5q31 MDS treated with lenalidomide versus placebo in a randomized phase 3 clinical t
Edgington, Eugene
2007-01-01
Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani
Rosemann Thomas
2011-04-01
Full Text Available Abstract Background The purpose of this study was to investigate the effect of short-term supplementation of amino acids before and during a 100 km ultra-marathon on variables of skeletal muscle damage and muscle soreness. We hypothesized that the supplementation of amino acids before and during an ultra-marathon would lead to a reduction in the variables of skeletal muscle damage, a decrease in muscle soreness and an improved performance. Methods Twenty-eight experienced male ultra-runners were divided into two groups, one with amino acid supplementation and the other as a control group. The amino acid group was supplemented a total of 52.5 g of an amino acid concentrate before and during the 100 km ultra-marathon. Pre- and post-race, creatine kinase, urea and myoglobin were determined. At the same time, the athletes were asked for subjective feelings of muscle soreness. Results Race time was not different between the groups when controlled for personal best time in a 100 km ultra-marathon. The increases in creatine kinase, urea and myoglobin were not different in both groups. Subjective feelings of skeletal muscle soreness were not different between the groups. Conclusions We concluded that short-term supplementation of amino acids before and during a 100 km ultra-marathon had no effect on variables of skeletal muscle damage and muscle soreness.
A. K. Bhunia
2011-04-01
Full Text Available In this paper, a single item deterministic inventory model with two separate warehouses called owned warehouse/show-room (OW and rented warehouse (RW is developed. The proposed model of this paper also considers a realistic assumption regarding the storage capacity of the rented warehouse. Demand is a function of selling price, advertisement of an item and displayed inventory level in OW. The stocks of RW are shipped to OW under bulk release pattern where shortages are not allowed. We discuss different scenarios of the proposed model to address relative size of stock dependency parameters and the capacity of owned warehouse. For each scenario, the corresponding problem is formulated as a constrained mixed integer nonlinear programming problem with three integer and two non-integer variables and a real coded genetic algorithm (RCGA is developed to solve the resulted problem. The proposed model of the paper is also examined using some numerical examples and sensitivity analysis is performed.
Computer-Assisted Dieting: Effects of a Randomized Nutrition Intervention
Schroder, Kerstin E. E.
2011-01-01
Objectives: To compare the effects of a computer-assisted dieting intervention (CAD) with and without self-management training on dieting among 55 overweight and obese adults. Methods: Random assignment to a single-session nutrition intervention (CAD-only) or a combined CAD plus self-management group intervention (CADG). Dependent variables were…
Sunanda Kane
2008-09-01
Full Text Available Sunanda Kane1, William Holderman2, Peter Jacques2, Todd Miodek31Mayo Clinic College of Medicine, Rochester, MN, USA; 2Digestive Health Specialists, Tacoma, WA, USA; 3University of Chicago, Chicago, IL, USABackground and Aims: Multiple studies have demonstrated the efficacy of aminosalicylates in maintaining remission in ulcerative colitis (UC. A newer formulation of mesalamine can be administered once daily. We aimed to examine the efficacy and tolerability of pH-dependent mesalamine for long-term maintenance, and compare the rates of medication consumption between groups over a prolonged period.Methods: Subjects whose UC had been quiescent for at least 4 months, and who had been receiving mesalamine for maintenance only, were randomized to once daily or conventional dosing for 12 months. Disease activity and medication consumption was assessed every 3 months. The primary endpoint was the percentage of those with quiescent disease at 12 months.Results: We enrolled 20 patients, 12 to once daily and 8 to conventional dosing. Six of the 12 patients (50% in the once daily group compared with 5 of the 8 patients (62.5% in the conventional group experienced a flare (p = 0.31. Only 5 of the 12 (42% patients in the once daily group were adherent compared with 3 of 8 patients (37.5% in the conventional dosing group (p = NS. Median amount consumed in the once daily group was 63% (range 0%–100% and in the conventional group 55% (range 0%–100%, (p > 0.5. None of the adherent subjects in the once daily group experienced a flare, while 6 out of 7 (86% who were non-adherent experienced a flare (p < 0.01. In the conventional dosing group, 1 in 3 adherent patients (33% experienced a fl are compared with 4 out of 5 (80% in the non-adherent group (p < 0.01.Conclusion: Adherence, rather than medication regimen, appeared to be important in disease outcome at 12 months.Keywords: ulcerative colitis, mesalamine, aminosalicylates, remission
Jianping Chu; Xueli Shen; Jun Fan; Changhai Chen; Shuyang Lin
2008-01-01
BACKGROUND: Heart rate variability refers to the beat-to-beat alteration in heart rate. It is usually a slight periodic variation of R-R intervals. Much information of autonomic nerve system balance can be obtained by measuring the heart rate variability of patients. It remains to be shown whether heart rate variability can be used as an index for determining the severity of insomnia and cerebral infarction. OBJECTIVE: This study aimed to analyze the correlation for each frequency spectrum parameter of heart rate variability with an insomnia index, as well as the degree of neurological defects in patients with simple cerebral infarction and cerebral infarction complicated by insomnia. The goal was to verify the feasibility of frequency spectrum parameters for heart rate variability as a marker for insomnia and cerebral infarction. DESIGN: A case-control observation. SETTING: Department of Neurology, First Hospital Affiliated to China Medical University. PARTICIPANTS: Sixty inpatients, and/or outpatients, with cerebral infarction were admitted to the 202 Hospital of Chinese PLA between December 2005 and October 2006, confirmed by CT, and recruited to the study. According to the insomnia condition (insomnia is defined by a Pittsburgh Sleep Quality Index score > 7), the patients were assigned to a simple cerebral infarction group and a cerebral infarction complicated by insomnia group, with 30 subjects in each group. Thirty additional subjects, who concurrently received ex-aminations and were confirmed to not suffer from cerebral infarction and insomnia, were recruited into the control group. Written informed consent was obtained from each subject for laboratory specimens. The pro-tocol was approved by the Hospital's Ethics Committee. METHODS: Following admission, each subject's neurological impairment was assessed with the National Institutes of Health Stroke Scale and Pittsburgh Sleep Quality Index. Heart rate variability of each subject was measured with an
Luanda A. C. Grecco
2014-10-01
Full Text Available Background: Transcranial direct-current stimulation (tDCS has been widely studied with the aim of enhancing local synaptic efficacy and modulating the electrical activity of the cortex in patients with neurological disorders. Objective: The purpose of the present study was to determine the effect of a single session of tDCS regarding immediate changes in spatiotemporal gait and oscillations of the center of pressure (30 seconds in children with cerebral palsy (CP. Method: A randomized controlled trial with a blinded evaluator was conducted involving 20 children with CP between six and ten years of age. Gait and balance were evaluated three times: Evaluation 1 (before the stimulation, Evaluation 2 (immediately after stimulation, and Evaluation 3 (20 minutes after the stimulation. The protocol consisted of a 20-minute session of tDCS applied to the primary motor cortex at an intensity of 1 mA. The participants were randomly allocated to two groups: experimental group - anodal stimulation of the primary motor cortex; and control group - placebo transcranial stimulation. Results: Significant reductions were found in the experimental group regarding oscillations during standing in the anteroposterior and mediolateral directions with eyes open and eyes closed in comparison with the control group (p<0.05. In the intra-group analysis, the experimental group exhibited significant improvements in gait velocity, cadence, and oscillation in the center of pressure during standing (p<0.05. No significant differences were found in the control group among the different evaluations. Conclusion: A single session of tDCS applied to the primary motor cortex promotes positive changes in static balance and gait velocity in children with cerebral palsy.
Creel, Scott; Creel, Michael
2009-11-01
1. Sampling error in annual estimates of population size creates two widely recognized problems for the analysis of population growth. First, if sampling error is mistakenly treated as process error, one obtains inflated estimates of the variation in true population trajectories (Staples, Taper & Dennis 2004). Second, treating sampling error as process error is thought to overestimate the importance of density dependence in population growth (Viljugrein et al. 2005; Dennis et al. 2006). 2. In ecology, state-space models are used to account for sampling error when estimating the effects of density and other variables on population growth (Staples et al. 2004; Dennis et al. 2006). In econometrics, regression with instrumental variables is a well-established method that addresses the problem of correlation between regressors and the error term, but requires fewer assumptions than state-space models (Davidson & MacKinnon 1993; Cameron & Trivedi 2005). 3. We used instrumental variables to account for sampling error and fit a generalized linear model to 472 annual observations of population size for 35 Elk Management Units in Montana, from 1928 to 2004. We compared this model with state-space models fit with the likelihood function of Dennis et al. (2006). We discuss the general advantages and disadvantages of each method. Briefly, regression with instrumental variables is valid with fewer distributional assumptions, but state-space models are more efficient when their distributional assumptions are met. 4. Both methods found that population growth was negatively related to population density and winter snow accumulation. Summer rainfall and wolf (Canis lupus) presence had much weaker effects on elk (Cervus elaphus) dynamics [though limitation by wolves is strong in some elk populations with well-established wolf populations (Creel et al. 2007; Creel & Christianson 2008)]. 5. Coupled with predictions for Montana from global and regional climate models, our results
A-Collapsibility of Distribution Dependence and Quantile Regression Coefficients
Meerschaert, Mark M
2010-01-01
The Yule-Simpson paradox notes that an association between random variables can be reversed when averaged over a background variable. Cox and Wermuth (2003) introduced the concept of distribution dependence between two random variables X and Y , and developed two dependence conditions, each of which guarantees that reversal cannot occur. Ma, Xie and Geng (2006) studied the collapsibility of distribution dependence over a background variable W, under a rather strong homogeneity condition. Collapsibility ensures the association remains the same for conditional and marginal models, so that Yule-Simpson reversal cannot occur. In this paper, we investigate a more general condition for avoiding e?ect reversal: A-collapsibility. The conditions of Cox and Wermuth imply A-collapsibility, without assuming homogeneity. In fact, we show that, when W is a binary variable, collapsibility is equivalent to A-collapsibility plus homogeneity, and A-collapsibility is equivalent to the conditions of Cox and Wermuth. Recently, Co...
Some general random Taylor series
孙道椿; 余家荣
1996-01-01
Kahane has studied the value distribution of Gauss-Taylor series where is a complex Gauss sequence and The value distribution of more general random Taylor series is considered, where {Xn} is a sequence of real or complex random variables of independent, symmetric and equally distributed with finite non-zero fourth moment (the classical Gauss, Steinhaus and Rademacher random variables are special cases of such variables). First a theorem on the growth of characteristic functions is proved by a method which is completely different from Kahane’s. Then it is applied to proving that the range of general random Taylor series is almost surely dense everywhere in the complex plane and that if the random variable is bounded and continuous, the random series surely has no finite Nevanlinna deficient value.
Murphy, B. P.; Johnson, J. P.
2012-12-01
in the length scale for the reduction in chemical weathering below the surface, or the flushing depth. The flushing depth is assumed to scale linearly with MAP, but decreases exponentially with increasing soil depth, as soil capillarity will imbibe infiltration. Modeling six MAP regimes between 500 and 3000 mm produces a non-linear increase in soil depths from 0.59 m soil to 5.15 m, which is broadly consistent with field observations from Kohala Peninsula. The median corestone grain size (D50) was calculated at model completion for the 20 blocks below the soil-rock interface. In the driest regime the D50 was 98% of that for the initial column, while the D50 for the wettest regime was 56% of the initial. This sediment preparation model predicts soil depths and tracks particle size reduction with variable climate-dependent weathering rates. Incorporating this type of model into sediment-transport dependent landscape evolution models may be the key to understanding the systematic differences in topography across spatially variable climate gradients, such as Kohala Peninsula.
Ke, Ming-Jen; Chen, Liang-Cheng; Chou, Yu-Ching; Li, Tsung-Ying; Chu, Heng-Yi; Tsai, Chia-Kuang; Wu, Yung-Tsan
2016-01-01
Recently, extracorporeal shock wave therapy (ESWT) has been shown to be a novel therapy for carpal tunnel syndrome (CTS). However, previous studies did not examine the diverse effects of different-session ESWT for different-grades CTS. Thus, we conducted a randomized, single-blind, placebo-controlled study. Sixty-nine patients (90 wrists) with mild to moderate CTS were randomized into 3 groups. Group A and C patients received one session of radial ESWT (rESWT) and sham eESWT per week for 3 co...
Wanscher, Jørgen Bundgaard; Sørensen, Majken Vildrik
2006-01-01
highly uniform multidimensional draws, which are highly relevant for todays traffic models. This paper shows among others combined shuffling and scrambling seems needless, that scrambling gives the lowest correlation and that there are detectable differences between random numbers, dependent...
Satoh, N.; Fukuda, H.; Miyairi, Y.; Yokoyama, Y.; Nagata, T.
2015-12-01
Radiocarbon in dissolved inorganic carbon (DIC) in seawater varies greatly, both geographically and with depth. This "reservoir effect" is thought to be reflected in the radiocarbon content (∆14C) of marine organisms, via DIC fixation by primary producers and subsequent trophic transfer. The ∆14C of marine organismal soft tissues might thus provide unique information about their habitats, diets, migration and other environmental histories. However, the effectiveness of this approach has yet to be extensively explored, with data on ∆14C variability in soft tissues of marine organisms being markedly limited. Here we examined whether ∆14C values of individual pinnate blades (leaf-like structures) of brown seaweed (Undaria pinnatifida) reflect the ∆14C of DIC in the water current prevailing at the time of blade formation. The study was conducted in Otsuchi Bay located in the Sanriku coastal region, northeastern Japan, where 14C-depleted cold Oyashio current and warm Tsugaru current (high ∆14C) converge, affecting the physiology and growth of marine organisms growing there. U. pinnatifida individuals cultured in the bay (length of saprophytes, 140-215 cm) were harvested in April 2014 and ∆14C of blades were determined by accelerator mass spectrometry. Younger blades formed after the Oyashio water intrusion had significantly lower ∆14C values compared to older blades formed before the event. The ∆14C values of younger and older blades were generally consistent with the ∆14C of DIC in Oyashio (-60.5 ‰) and Tsugaru (24.9 ‰) waters, respectively. Thus, despite possible turnover of organic carbon in seaweed soft tissues, blade-order-dependent ∆14C variability appeared to strongly reflect the Oyashio intrusion event (radiocarbon shift) in the bay.
Juliana Petrini
2012-12-01
Full Text Available The objective of this work was to assess the degree of multicollinearity and to identify the variables involved in linear dependence relations in additive-dominant models. Data of birth weight (n=141,567, yearling weight (n=58,124, and scrotal circumference (n=20,371 of Montana Tropical composite cattle were used. Diagnosis of multicollinearity was based on the variance inflation factor (VIF and on the evaluation of the condition indexes and eigenvalues from the correlation matrix among explanatory variables. The first model studied (RM included the fixed effect of dam age class at calving and the covariates associated to the direct and maternal additive and non-additive effects. The second model (R included all the effects of the RM model except the maternal additive effects. Multicollinearity was detected in both models for all traits considered, with VIF values of 1.03 - 70.20 for RM and 1.03 - 60.70 for R. Collinearity increased with the increase of variables in the model and the decrease in the number of observations, and it was classified as weak, with condition index values between 10.00 and 26.77. In general, the variables associated with additive and non-additive effects were involved in multicollinearity, partially due to the natural connection between these covariables as fractions of the biological types in breed composition.O objetivo deste trabalho foi avaliar o grau de multicolinearidade e identificar as variáveis envolvidas na dependência linear em modelos aditivo-dominantes. Foram utilizados dados de peso ao nascimento (n=141.567, peso ao ano (n=58.124 e perímetro escrotal (n=20.371 de bovinos de corte compostos Montana Tropical. O diagnóstico de multicolinearidade foi baseado no fator de inflação de variância (VIF e no exame dos índices de condição e dos autovalores da matriz de correlações entre as variáveis explanatórias. O primeiro modelo estudado (RM incluiu o efeito fixo de classe de idade da mãe ao parto e
Liu, Zhiyong; Menzel, Lucas
2016-12-01
Geographic time series are usually non-stationary and contain different frequency components (e.g., seasonal variations, long-term and short-term fluctuations) which may significantly affect the overall variance structure in the original data. Based upon the monthly normalized difference vegetation index (NDVI), precipitation and temperature data for six different vegetation types in two precipitation regimes (low and high precipitation regimes) of Rhineland-Palatinate (Southwest Germany), this study aims to examine the temporal trends in the original time series of these variables and their relationships. In addition, the further objectives are to evaluate which time-scale is dominantly responsible for the trend production found in the original data and find out the certain time-scales that represent the strongest correlation between NDVI and climatic variables (i.e., precipitation and temperature). A combined approach using the discrete wavelet transform (DWT), Mann-Kendall (MK) trend test and correlation analysis was implemented to achieve these goals. The trend assessment for the original data shows that the monthly NDVI time series for all vegetation types in both precipitation regimes have upward trends, most of which are significant. The precipitation and temperature data for six vegetation types in two precipitation regimes present weak downward trends and significant increasing trends, respectively. The most important time-scales contributing the trend production in the original NDVI data are the 2-month and 8-month events. For precipitation, the most influential ones are 2-month and 4-month scales. The 4-month periodic mode predominantly affects the trends in the original temperature time series. Based on the original time series, the change in temperature is found to be the primary driver influencing the variability in vegetation greenness over this study area, while there is a negative correlation between NDVI and precipitation for all vegetation types
Ackerman, Margaret; Saunders, Kevin O.; Pollara, Justin; Vandergrift, Nathan; Parks, Rob; Michael, Nelson L.; O’Connell, Robert J.; Vasan, Sandhya; Rerks-Ngarm, Supachai; Kaewkungwal, Jaranit; Pitisuttithum, Punnee; Nitayaphan, Sorachai; Sinangil, Faruk; Phogat, Sanjay; Alam, S. Munir; Liao, Hua-Xin; Ferrari, Guido; Seaman, Michael S.; Montefiori, David C.; Harrison, Stephen C.; Haynes, Barton F.
2017-01-01
The canary pox vector and gp120 vaccine (ALVAC-HIV and AIDSVAX B/E gp120) in the RV144 HIV-1 vaccine trial conferred an estimated 31% vaccine efficacy. Although the vaccine Env AE.A244 gp120 is antigenic for the unmutated common ancestor of V1V2 broadly neutralizing antibody (bnAbs), no plasma bnAb activity was induced. The RV305 (NCT01435135) HIV-1 clinical trial was a placebo-controlled randomized double-blinded study that assessed the safety and efficacy of vaccine boosting on B cell repertoires. HIV-1-uninfected RV144 vaccine recipients were reimmunized 6–8 years later with AIDSVAX B/E gp120 alone, ALVAC-HIV alone, or a combination of ALVAC-HIV and AIDSVAX B/E gp120 in the RV305 trial. Env-specific post-RV144 and RV305 boost memory B cell VH mutation frequencies increased from 2.9% post-RV144 to 6.7% post-RV305. The vaccine was well tolerated with no adverse events reports. While post-boost plasma did not have bnAb activity, the vaccine boosts expanded a pool of envelope CD4 binding site (bs)-reactive memory B cells with long third heavy chain complementarity determining regions (HCDR3) whose germline precursors and affinity matured B cell clonal lineage members neutralized the HIV-1 CRF01 AE tier 2 (difficult to neutralize) primary isolate, CNE8. Electron microscopy of two of these antibodies bound with near-native gp140 trimers showed that they recognized an open conformation of the Env trimer. Although late boosting of RV144 vaccinees expanded a novel pool of neutralizing B cell clonal lineages, we hypothesize that boosts with stably closed trimers would be necessary to elicit antibodies with greater breadth of tier 2 HIV-1 strains. Trial Registration: ClinicalTrials.gov NCT01435135 PMID:28235027
Soichiro Kaneko
2013-01-01
Full Text Available Objective. We investigated the relationship between superior mesenteric artery blood flow volume (SMA BFV and autonomic nerve activity in acupuncture stimulation of lower limb points through heart rate variability (HRV evaluations. Methods. Twenty-six healthy volunteers underwent crossover applications of bilateral manual acupuncture stimulation at ST36 or LR3 or no stimulation. Heart rate, blood pressure, cardiac index, systemic vascular resistance index, SMA BFV, and HRV at rest and 30 min after the intervention were analyzed. Results. SMA BFV showed a significant increase after ST36 stimulation (0% to 14.1% ± 23.4%, P=0.007; very low frequency (VLF, high frequency (HF, low frequency (LF, and LF/HF were significantly greater than those at rest (0% to 479.4% ± 1185.6%, P=0.045; 0% to 78.9% ± 197.6%, P=0.048; 0% to 123.9% ± 217.1%, P=0.006; 0% to 71.5% ± 171.1%, P=0.039. Changes in HF and LF also differed significantly from those resulting from LR3 stimulation (HF: 78.9% ± 197.6% versus −18.2% ± 35.8%, P=0.015; LF: 123.9% ± 217.1% versus 10.6% ± 70.6%, P=0.013. Conclusion. Increased vagus nerve activity after ST36 stimulation resulted in increased SMA BFV. This partly explains the mechanism of acupuncture-induced BFV changes.
Hooi, Paul
2013-01-01
To determine how the variability in biaxial flexure strength of a soda-lime glass analogue for a PLV and DBC material was influenced by precementation operative variables and following resin-cement coating.
GUO TieXin; CHEN XinXiang
2009-01-01
The purpose of this paper is to provide a random duality theory for the further development of the theory of random conjugate spaces for random normed modules.First,the complicated stratification structure of a module over the algebra L(μ,K) frequently makes our investigations into random duality theory considerably different from the corresponding ones into classical duality theory,thus in this paper we have to first begin in overcoming several substantial obstacles to the study of stratification structure on random locally convex modules.Then,we give the representation theorem of weakly continuous canonical module homomorphisms,the theorem of existence of random Mackey structure,and the random bipolar theorem with respect to a regular random duality pair together with some important random compatible invariants.
无
2009-01-01
The purpose of this paper is to provide a random duality theory for the further development of the theory of random conjugate spaces for random normed modules. First, the complicated stratification structure of a module over the algebra L(μ, K) frequently makes our investigations into random duality theory considerably difierent from the corresponding ones into classical duality theory, thus in this paper we have to first begin in overcoming several substantial obstacles to the study of stratification structure on random locally convex modules. Then, we give the representation theorem of weakly continuous canonical module homomorphisms, the theorem of existence of random Mackey structure, and the random bipolar theorem with respect to a regular random duality pair together with some important random compatible invariants.
Morgan, Erin E.; Woods, Steven Paul; Grant, Igor
2012-01-01
Although HIV-associated neurocognitive disorders (HAND) are the strong predictors of everyday functioning difficulties, approximately half of all functionally impaired individuals are labeled “neurocognitively normal” according to the standard neuropsychological measures, suggesting that novel predictors of functional problems in this prevalent subgroup are needed. The present study hypothesized that increased neurocognitive intra-individual variability as indexed by dispersion would be associated with poor daily functioning among 82 persons with HIV infection who did not meet research criteria for HAND. An intra-individual standard deviation was calculated across the demographically adjusted T-scores of 13 standard neuropsychological tests to represent dispersion, and functional outcomes included self-reported declines in basic and instrumental activities of daily functioning (basic activity of daily living [BADL] and instrumental activity of daily living [IADL], respectively) and medication management. Dispersion was a significant predictor of medication adherence and dependence in both BADL and IADL, even when other known predictors of functional status (i.e., age, affective distress, and indices of disease severity) were included in the models. As a significant and unique predictor of a performance on the range of daily functioning activities, neurocognitive dispersion may be indicative of deficient cognitive control expressed as inefficient regulation of neurocognitive resources in the context of competing functional demands. As such, dispersion may have clinical utility in detecting risk for functional problems among HIV-infected individuals without HAND. PMID:22337933
Dynamic Quantum Allocation and Swap-Time Variability in Time-Sharing Operating Systems.
Bhat, U. Narayan; Nance, Richard E.
The effects of dynamic quantum allocation and swap-time variability on central processing unit (CPU) behavior are investigated using a model that allows both quantum length and swap-time to be state-dependent random variables. Effective CPU utilization is defined to be the proportion of a CPU busy period that is devoted to program processing, i.e.…
A Composite Likelihood Inference in Latent Variable Models for Ordinal Longitudinal Responses
Vasdekis, Vassilis G. S.; Cagnone, Silvia; Moustaki, Irini
2012-01-01
The paper proposes a composite likelihood estimation approach that uses bivariate instead of multivariate marginal probabilities for ordinal longitudinal responses using a latent variable model. The model considers time-dependent latent variables and item-specific random effects to be accountable for the interdependencies of the multivariate…
φ-混合随机变量序列收敛性质的若干新结果%Some New Convergence Properties for φ-mixing Random Variable Sequences
沈爱婷
2011-01-01
In this paper, we extend the Kolmogorov-type inequality to the case of φ-mixing sequences. Moreover, we study the strong limit theorems for partial sums of φ-mixing random variables. As a result, we extend the Khintchine-Kolmogorov-type convergence theorem, the three series theorem, Marcitlkiewicz strong law of large number to the case of φ-mixig sequences.%本文将Kolmogorov型不等式推广到φ-混合序列,并且研究其强收敛性质,得到了φ-混合序列的Khintchine-Kolmogorov型收敛定理、三级数定理和Marcitlkiewicz型强大数定律.
姜斌; 罗阿理; 赵永恒
2012-01-01
提出一种适用于在郭守敬望远镜海量光谱中自动、快速筛选激变变星的方法.利用已证认的激变变星光谱作为模板,通过随机森林分类训练,得到一个分类模型,该模型给出了各个波长对应流量的重要性排序,可根据该排序进行降维并用于激变变星判别,结果作为反馈进一步丰富模板库.实验中共发现了16个新的激变变星候选体,表明了该方法的可行性.%An automatic and efficient method for cataclysmic variables candidates is presented in the present paper. The identified CVs were selected as templates. A model was constructed by random forest algorithm with templates and random selected spectra. Wavelength ranking was described by the model and the classifier was constructed afterwards. Most of the non-candidates were excluded by the method. Template matching strategy was used to identify the final candidates which were analyzed to complement the templates as feedback. 16 new CVs candidates were found in the experiment that shows that our approach to finding special celestial bodies can be feasible in LAMOST.
Asymptotics of Random Contractions
Hashorva, Enkelejd; Tang, Qihe
2010-01-01
In this paper we discuss the asymptotic behaviour of random contractions $X=RS$, where $R$, with distribution function $F$, is a positive random variable independent of $S\\in (0,1)$. Random contractions appear naturally in insurance and finance. Our principal contribution is the derivation of the tail asymptotics of $X$ assuming that $F$ is in the max-domain of attraction of an extreme value distribution and the distribution function of $S$ satisfies a regular variation property. We apply our result to derive the asymptotics of the probability of ruin for a particular discrete-time risk model. Further we quantify in our asymptotic setting the effect of the random scaling on the Conditional Tail Expectations, risk aggregation, and derive the joint asymptotic distribution of linear combinations of random contractions.
Shiffman, Bernard
2010-01-01
We introduce several notions of `random fewnomials', i.e. random polynomials with a fixed number f of monomials of degree N. The f exponents are chosen at random and then the coefficients are chosen to be Gaussian random, mainly from the SU(m + 1) ensemble. The results give limiting formulas as N goes to infinity for the expected distribution of complex zeros of a system of k random fewnomials in m variables. When k = m, for SU(m + 1) polynomials, the limit is the Monge-Ampere measure of a toric Kaehler potential on CP^m obtained by averaging a `discrete Legendre transform' of the Fubini-Study symplectic potential at f points of the unit simplex in R^m.
Schrantee, A.; Tamminga, H.G.H.; Bouziane, C.; Bottelier, M.A.; Bron, E.E.; Mutsaerts, H.J.M.M.; Zwinderman, A.H.; Groote, I.R.; Rombouts, S.A.R.B.; Lindauer, R.J.L.; Klein, S.; Niessen, W.J.; Opmeer, B.C.; Boer, F.; Lucassen, P.J.; Andersen, S.L.; Geurts, H.M.; Reneman, L.
2016-01-01
Importance: Although numerous children receive methylphenidate hydrochloride for the treatment of attention-deficit/hyperactivity disorder (ADHD), little is known about age-dependent and possibly lasting effects of methylphenidate on the human dopaminergic system. Objectives: To determine whether th
Madigan, Kevin
2013-01-01
Patients who experience the onset of psychotic illness with a comorbid diagnosis of cannabis dependence experience poor clinical outcomes. Few studies have identified interventions that reduce cannabis use and improve clinical outcome in this population.
Drop Spreading with Random Viscosity
Xu, Feng; Jensen, Oliver
2016-11-01
Airway mucus acts as a barrier to protect the lung. However as a biological material, its physical properties are known imperfectly and can be spatially heterogeneous. In this study we assess the impact of these uncertainties on the rate of spreading of a drop (representing an inhaled aerosol) over a mucus film. We model the film as Newtonian, having a viscosity that depends linearly on the concentration of a passive solute (a crude proxy for mucin proteins). Given an initial random solute (and hence viscosity) distribution, described as a Gaussian random field with a given correlation structure, we seek to quantify the uncertainties in outcomes as the drop spreads. Using lubrication theory, we describe the spreading of the drop in terms of a system of coupled nonlinear PDEs governing the evolution of film height and the vertically-averaged solute concentration. We perform Monte Carlo simulations to predict the variability in the drop centre location and width (1D) or area (2D). We show how simulation results are well described (at much lower computational cost) by a low-order model using a weak disorder expansion. Our results show for example how variability in the drop location is a non-monotonic function of the solute correlation length increases. Engineering and Physical Sciences Research Council.
Luís André Castro
2009-01-01
Full Text Available OBJETIVO: O objetivo deste estudo é avaliar a eficácia da naltrexona com intervenção breve em pacientes com dependência de álcool. MÉTODO: Este estudo é um ensaio clínico randomizado, duplo-cego, placebo-controlado de 12 semanas. A amostra de 71 pacientes foi dividida randomicamente em dois grupos (um recebendo naltrexona e outro placebo. Sujeitos dependentes de álcool foram tratados com 50 mg de naltrexona ou placebo diariamente por 12 semanas. Ambos os grupos de tratamento receberam intervenção breve. Os desfechos clínicos primários para este estudo foram taxa de recaída e mudança no padrão de consumo de álcool. RESULTADOS: Na intenção de tratar, menor porcentagem de sujeitos tratados com naltrexona recaíram (3% 21%; p = 0,054. Naltrexona com intervenção breve não foi superior ao placebo para diminuir os dias de consumo (6,2 + 10,6 3,05 + 7,3; p = 0,478, os dias de consumo moderado (0 2,2 + 6,9; p = 0,345 e os dias de consumo pesado (0,03 + 0,2 0,3 + 0,9; p = 0,887. Naltrexona foi bem tolerada. Os efeitos adversos mais frequentes na presente amostra foram: cefaleia (25,4%, sonolência (20,9%, náuseas (16,4%, hiperfagia (16,4%, anorexia (14,9%, ansiedade (10,4%, pirose (10,4% e irritabilidade (10,4%. CONCLUSÕES: Embora o grupo naltrexona tenha demonstrado tendência para reduzir taxa de recaída (> 5 doses/dia, não foi encontrada nenhuma diferença em outras variáveis de consumo de álcool entre os grupos naltrexona e placebo. Estudos futuros devem examinar a eficácia desse tipo de combinação de tratamento nos cuidados primários de saúde.OBJECTIVE: The objective of this study is to evaluate the efficacy of naltrexone with brief intervention among patients with alcohol dependence. METHOD: This study is a 12-week randomized, double blind, placebo-controlled clinical trial. The sample of 71 patients was randomly divided in two groups (one receiving naltrexone and the other placebo. Alcohol-dependent subjects were
Holtmann, Henrik; Niewald, Marcus; Prokein, Benjamin; Graeber, Stefan; Ruebe, Christian
2015-01-01
Background An actual clinical trial showed the effect of low dose radiotherapy in painful heel spur (plantar fasciitis) with single doses of 1.0 Gy and total doses of 6.0 Gy applied twice weekly. Furthermore, a lot of animal experimental and in vitro data reveals the effect of lower single doses of 0.5 Gy which may be superior in order to ease pain and reduce inflammation in patients with painful heel spur. Our goal is therefore to transfer this experimentally found effect into a randomized m...
Ke, Ming-Jen; Chen, Liang-Cheng; Chou, Yu-Ching; Li, Tsung-Ying; Chu, Heng-Yi; Tsai, Chia-Kuang; Wu, Yung-Tsan
2016-12-02
Recently, extracorporeal shock wave therapy (ESWT) has been shown to be a novel therapy for carpal tunnel syndrome (CTS). However, previous studies did not examine the diverse effects of different-session ESWT for different-grades CTS. Thus, we conducted a randomized, single-blind, placebo-controlled study. Sixty-nine patients (90 wrists) with mild to moderate CTS were randomized into 3 groups. Group A and C patients received one session of radial ESWT (rESWT) and sham eESWT per week for 3 consecutive weeks, respectively; Group B patients received a single session of rESWT. The night splint was also used in all patients. The primary outcome was Boston Carpal Tunnel Syndrome Questionnaire (BCTQ) points, whereas secondary outcomes included the sensory nerve conduction velocity and cross-sectional area of the median nerve. Evaluations were performed at 4, 10, and 14 weeks after the first session of rESWT. Compared to the control group, the three-session rESWT group demonstrated significant BCTQ point reductions at least 14 weeks, and the effect was much longer lasting in patients with moderate CTS than mild CTS. In contrast, the effect of single-session rESWT showed insignificant comparison. rESWT is a valuable strategy for treating CTS and multiple-session rESWT has a clinically cumulative effect.
Garland, Eric L; Roberts-Lewis, Amelia; Tronnier, Christine D; Graves, Rebecca; Kelley, Karen
2016-02-01
In many clinical settings, there is a high comorbidity between substance use disorders, psychiatric disorders, and traumatic stress. Novel therapies are needed to address these co-occurring issues efficiently. The aim of the present study was to conduct a pragmatic randomized controlled trial comparing Mindfulness-Oriented Recovery Enhancement (MORE) to group Cognitive-Behavioral Therapy (CBT) and treatment-as-usual (TAU) for previously homeless men residing in a therapeutic community. Men with co-occurring substance use and psychiatric disorders, as well as extensive trauma histories, were randomly assigned to 10 weeks of group treatment with MORE (n = 64), CBT (n = 64), or TAU (n = 52). Study findings indicated that from pre-to post-treatment MORE was associated with modest yet significantly greater improvements in substance craving, post-traumatic stress, and negative affect than CBT, and greater improvements in post-traumatic stress and positive affect than TAU. A significant indirect effect of MORE on decreasing craving and post-traumatic stress by increasing dispositional mindfulness was observed, suggesting that MORE may target these issues via enhancing mindful awareness in everyday life. This pragmatic trial represents the first head-to-head comparison of MORE against an empirically-supported treatment for co-occurring disorders. Results suggest that MORE, as an integrative therapy designed to bolster self-regulatory capacity, may hold promise as a treatment for intersecting clinical conditions.
A Stochastic Collocation Method for Elliptic Partial Differential Equations with Random Input Data
Babuška, Ivo
2010-01-01
This work proposes and analyzes a stochastic collocation method for solving elliptic partial differential equations with random coefficients and forcing terms. These input data are assumed to depend on a finite number of random variables. The method consists of a Galerkin approximation in space and a collocation in the zeros of suitable tensor product orthogonal polynomials (Gauss points) in the probability space, and naturally leads to the solution of uncoupled deterministic problems as in the Monte Carlo approach. It treats easily a wide range of situations, such as input data that depend nonlinearly on the random variables, diffusivity coefficients with unbounded second moments, and random variables that are correlated or even unbounded. We provide a rigorous convergence analysis and demonstrate exponential convergence of the “probability error” with respect to the number of Gauss points in each direction of the probability space, under some regularity assumptions on the random input data. Numerical examples show the effectiveness of the method. Finally, we include a section with developments posterior to the original publication of this work. There we review sparse grid stochastic collocation methods, which are effective collocation strategies for problems that depend on a moderately large number of random variables.
Poisson Random Variate Generation.
1981-12-01
Poisson have been proposed. Atkinson [5] includes the approach developed in Marsaglia £15) and Norman and Cannon £16) which is based on composition...34, Naval Research Logistics Quarterly, 26, 3, 403-413. 15. Marsaglia , G. (1963). "Generating Discrete Random Variables in a Computer", Communications
Loss aversion with a state-dependent reference point
Georgi, Enrico; Post, Thierry
2010-01-01
This study investigates loss aversion when the reference point is a state-dependent random variable. This case describes, for example, a money manager being evaluated relative to a risky benchmark index rather than a fixed target return level. Using a state-dependent structure, prospects are more (less) attractive if they depend positively (negatively) on the reference point. In addition, the structure avoids an inherent aversion to risky prospects and yields no losses when the prospect and t...
周任军; 刘志勇; 李献梅; 陈瑞先; 闵雄帮; 尹权
2014-01-01
The benefit of carbon capture unit closely relates with electricity price and price of carbon emission permit, in the optimization model of unit carbon capture rate, in which the cost of electricity selling, the cost of carbon emission permit transaction cost and the fuel cost are taken as variables in objective function, the randomness of the electricity price and the price of carbon emission permit are considered simultaneously, and a multiple random variable superquantile method is proposed and derived to turn the optimization model of unit carbon capture rate into the optimization model of unit carbon capture rate in the form of random function that is easy to solve by toolbox. Three kinds of calculation results, namely the price fluctuations of both electricity and carbon emission permit are not considered, only the price fluctuation of carbon emission permit is considered and the price fluctuations of both electricity and carbon emission permit are considered, are contrasted and analyzed. Case simulation results show that considering the price randomness of both electricity and carbon emission permit the flexibility of power grid to adjust the carbon capture rate is enhanced; the mechanism of electricity market and carbon trading market is actively responded, thus the overall operating cost of carbon capture system can be reduced.%碳捕集机组的效益与电价、碳排放权价格密切相关，在售电损失费用、碳排放权交易费用和燃料费用为目标函数的机组碳捕集率优化模型中，同时考虑电价与碳排放权价格的随机性，提出并推导了多随机变量超分位数方法，将机组碳捕集率优化模型变为机组碳捕集率随机函数型的优化模型，便于利用工具箱求解。对比分析了不考虑电价和碳排放权价格波动，仅考虑碳排放权价格波动以及考虑电价与碳排放权价格波动的机组碳捕集率优化模型的3种计算结果。算例仿真结果表明，同
Kim, Sungjun; Park, Byung-Gook
2016-12-01
A study on the bipolar-resistive switching of an Ni/SiN/Si-based resistive random-access memory (RRAM) device shows that the influences of the reset power and the resistance value of the low-resistance state (LRS) on the reset-switching transitions are strong. For a low LRS with a large conducting path, the sharp reset switching, which requires a high reset power (>7 mW), was observed, whereas for a high LRS with small multiple-conducting paths, the step-by-step reset switching with a low reset power (switching is due to the steep current-increased region of the trap-controlled space charge-limited current (SCLC) model. A multilevel cell (MLC) operation, for which the reset stop voltage (V STOP) is used in the DC sweep mode and an incremental amplitude is used in the pulse mode for the step-by-step reset switching, is demonstrated here. The results of the present study suggest that well-controlled conducting paths in a SiN-based RRAM device, which are not too strong and not too weak, offer considerable potential for the realization of low-power and high-density crossbar-array applications.
Carroll, Kathleen M.; Nich, Charla; Shi, Julia M.; Eagan, Dorothy; Ball, Samuel A.
2012-01-01
Background Cocaine use remains a major problem within methadone maintenance programs. Disulfiram’s efficacy in reducing cocaine use has been demonstrated in several trials, but its relative efficacy among individuals who use versus abstain from alcohol remains unclear Treatment approaches which seek to enhance substance users’ involvement in self-help activities (Twelve Step Facilitation, TSF) have been associated with better outcomes among alcohol and cocaine users, but have rarely been evaluated among methadone-maintained cocaine-opioid users. Methods We conducted a randomized, placebo controlled, double blind (for medication condition), factorial (2×2) trial with 4 treatment conditions: Disulfiram plus TSF, disulfiram plus standard counseling only, placebo plus TSF, and placebo plus standard counseling in the context of a community-based methadone maintenance program. Participants (N=112) received either disulfiram (250 mg/d) or placebo in conjunction with daily methadone maintenance. Results Assignment to TSF was associated with less cocaine use throughout treatment and a higher number of cocaine-negative urines. While there were no significant main effects of disulfiram versus placebo, individuals without an alcohol use disorder demonstrated greater reductions in cocaine use over time when assigned to disulfiram. Conclusions TSF appears feasible in this methadone maintenance program and was associated with modest reductions in cocaine use, an often intractable problem in this setting. Support for the efficacy of disulfiram was weaker, as it appeared effective only for those without a current alcohol use disorder for this sample. PMID:22695473
David Cameron-Smith
2009-12-01
Full Text Available The effect of resistance exercise with the ingestion of supplementary protein on the activation of the mTOR cascade, in human skeletal muscle has not been fully elucidated. In this study, the impact of a single bout of resistance exercise, immediately followed by a single dose of whey protein isolate (WPI or placebo supplement, on the activation of mTOR signalling was analyzed. Young untrained men completed a maximal single-legged knee extension exercise bout and were randomized to ingest either WPI supplement (n = 7 or the placebo (n = 7. Muscle biopsies were taken from the vastus lateralis before, and 2, 4 and 24 hr post-exercise. WPI or placebo ingestion consumed immediately post-exercise had no impact on the phosphorylation of Akt (Ser473. However, WPI significantly enhanced phosphorylation of mTOR (Ser2448, 4E-BP1 (Thr37/46 and p70S6K (Thr389 at 2 hr post-exercise. This study demonstrates that a single dose of WPI, when consumed in modest quantities, taken immediately after resistance exercise elicits an acute and transient activation of translation initiation within the exercised skeletal muscle.
Boguslawski, Martin; Armijo, Julien; Diebel, Falko; Rose, Patrick; Denz, Cornelia
2013-01-01
We present a method to demonstrate Anderson localization in an optically induced randomized potential. By usage of computer controlled spatial light modulators, we are able to implement fully randomized nondiffracting beams of variable structural size in order to control the modulation length (photonic grain size) as well as the depth (disorder strength) of a random potential induced in a photorefractive crystal. In particular, we quantitatively analyze the localization length of light depending on these two parameters and find that they are crucial influencing factors on the propagation behavior leading to variably strong localization. Thus, we corroborate that transverse light localization in a random refractive index landscape strongly depends on the character of the potential, allowing for a flexible regulation of the localization strength by adapting the optical induction configuration.
Stephanov, M A; Wettig, T
2005-01-01
We review elementary properties of random matrices and discuss widely used mathematical methods for both hermitian and nonhermitian random matrix ensembles. Applications to a wide range of physics problems are summarized. This paper originally appeared as an article in the Wiley Encyclopedia of Electrical and Electronics Engineering.
Forecasting Using Random Subspace Methods
T. Boot (Tom); D. Nibbering (Didier)
2016-01-01
textabstractRandom subspace methods are a novel approach to obtain accurate forecasts in high-dimensional regression settings. We provide a theoretical justification of the use of random subspace methods and show their usefulness when forecasting monthly macroeconomic variables. We focus on two appr
A Borderline Random Fourier Series
Talagrand, Michel
1995-01-01
Consider a mean zero random variable $X$, and an independent sequence $(X_n)$ distributed like $X$. We show that the random Fourier series $\\sum_{n\\geq 1} n^{-1} X_n \\exp(2i\\pi nt)$ converges uniformly almost surely if and only if $E(|X|\\log\\log(\\max(e^e, |X|))) < \\infty$.
苏淳; 梁汉营; 王岳宝
2000-01-01
在本部分中,采用由L'evy函数(4.1)所确定的值bn取代(I)［1］中的(1)/(n) ``分位点''an,使得(I)中定理1中的附加条件(A)得以解除, 从而获得了可以称之为Hsu-Robbins型的充分必要条件.作为推论,还给出了两个互为复制的iid随机变量三角阵对应行之和乘积的Kolmogorov强大数律.%In this part, we replace (1)/(n) quantilean by value bn, which is determined by L'evy function (4.1), suchthat the condition A of Theorem 1 in (I)［1］ is eliminated. Thenecessary and sufficient conditions that can been real called to beHsu-Robbins type theorem are obtained. As corollary we get theKolmogorov strong laws of large number for products of correspondingrowwise sums of triangular array of copy iid random variables.
Liu, Jing; Pedoia, Valentina; Heilmeier, Ursula; Ku, Eric; Su, Favian; Khanna, Sameer; Imboden, John; Graf, Jonathan; Link, Thomas; Li, Xiaojuan
2016-01-01
This study is to evaluate highly accelerated three-dimensional (3D) dynamic contrast-enhanced (DCE) wrist MRI for assessment of perfusion in rheumatoid arthritis (RA) patients. A pseudo-random variable-density undersampling strategy, circular Cartesian undersampling (CIRCUS), was combined with k-t SPARSE-SENSE reconstruction to achieve a highly accelerated 3D DCE wrist MRI. Two healthy volunteers and 10 RA patients were studied. Two patients were on methotrexate (MTX) only (Group I) and the other eight were treated with a combination therapy of MTX and anti-tumor necrosis factor (TNF) therapy (Group II). Patients were scanned at baseline and 3 month follow-up. DCE MR images were used to evaluate perfusion in synovitis and bone marrow edema pattern in the RA wrist joints. A series of perfusion parameters was derived and compared with clinical disease activity scores of 28 joints (DAS28). 3D DCE wrist MR images were obtained with a spatial resolution of 0.3 × 0.3 × 1.5 mm(3) and temporal resolution of 5 s (with an acceleration factor of 20). The derived perfusion parameters, most notably transition time (dT) of synovitis, showed significant negative correlations with DAS28-ESR (r = -0.80, p perfusion in RA joints, showing promise as a potential tool for evaluating treatment responses.
Distribution of levels in high-dimensional random landscapes
Kabluchko, Zakhar
2010-01-01
We prove empirical central limit theorems for the distribution of levels of various random fields defined on high-dimensional discrete structures as the dimension of the structure goes to $\\infty$. The random fields considered include costs of assignments, lengths of Hamiltonian cycles and spanning trees, energies of directed polymers, locations of particles in the branching random walk, as well as energies in the Sherrington--Kirkpatrick and Edwards--Anderson models. The distribution of levels in all models listed above is shown to be essentially the same as in a stationary Gaussian process with regularly varying non-summable covariance function. This type of behavior is different from the Brownian bridge-type limit known for independent or stationary weakly dependent sequences of random variables.
Taghadomi, Reza Jalaian; Golmakani, Ebrahim; Alizadeh, Kambiz; Mottahedi, Behrooz; Rahdari, Ali; Sheybani, Shima
2016-01-01
Background An increasing number of patients addicted to opium are experiencing awareness during coronary artery bypass surgery (CABG) as a result of tolerance to anesthetics. Objectives This research was primarily intended to determine the potential diminishing effects of moderate hypothermia on anesthetic dosage and recall of anesthesia during the procedure. Methods In this double-blind randomized controlled trial, a total of 80 CABG candidates with known addiction to opium were divided into two groups: one normothermic (N) and the other moderately hypothermic (H), both undergoing induction as well as close monitoring from September 2014 to January 2016. The candidates were initially set for a target bispectral index (BIS) score of between 40 and 60. As the score rose to 60, an additional dose of propofol was administered, alongside rise in blood pressure and tear-shedding. To enhance the accuracy of our evaluation of anesthetic depth, we also used two questionnaires to test candidates’ recall filled with the assistance of a colleague 24 hours following surgery. Independent-samples t-test and chi-square test were used by SPSS v 18 for data analysis. Results Eighty patients were studied in two groups of normothermic (N) (n = 40) and hypothermic (H) (n = 40). Given similar demographic data as well as the duration of surgery, we arrived at a propofol dose of 122.52±13.11 cc for normothermic patients and 101.28±14.06 cc for hypothermic subjects (p=0.001). As for fentanyl, the total required sum came up to 39.60±21.04 cc and 31.72±5.81 cc for the above-mentioned groups in order (p=0.025). Moreover, the post-operative interview showed that there was no report of a patient with memory recall following surgery. Conclusions Moderate hypothermia can substantially reduce the need for anesthetics in patients with addiction to opium when undergoing CABG surgery. Trial registration This study is registered in Iranian Registry of Clinical Trials with registration number of
Ireland, Michael J; Wood, Peter R
2011-01-01
We present 4 model series of the CODEX dynamical opacity-sampling models of Mira variables with solar abundances, designed to have parameters similar to $o$ Cet, R Leo and R Cas. We demonstrate that the CODEX models provide a clear physical basis for the molecular shell scenario used to explain interferometric observations of Mira variables. We show that these models generally provide a good match to photometry and interferometry at wavelengths between the near-infrared and the radio, and make the model outputs publicly available. These model also demonstrate that, in order to match visible and infrared observations, the Fe-poor silicate grains that form within 3 continuum radii must have small grain radii and therefore can not drive the winds from O-rich Mira variables.
Some consequences of exchangeability in random-matrix theory.
Le Caër, G; Delannay, R
1999-06-01
Properties of infinite sequences of exchangeable random variables result directly in explicit expressions for calculating asymptotic densities of eigenvalues rho(infinity)(lambda) of any ensemble of random matrices H whose distribution depends only on tr(H+H), where H+ is the Hermitian conjugate of H. For real symmetric matrices and for Hermitian matrices, the densities rho(infinity)(lambda) are constructed by summing up Wigner semicircles with varying radii and weights as confirmed by Monte Carlo simulations. Extensions to more general matrix ensembles are also considered.
Tail asymptotics for dependent subexponential diﬀerences
Albrecher, H; Asmussen, Søren; Kortschak, D.
We study the asymptotic behavior of P(X − Y > u) as u → ∞, where X is subexponential and X, Y are positive random variables that may be dependent. We give criteria under which the subtraction of Y does not change the tail behavior of X. It is also studied under which conditions the comonotonic co...
ajansen; kwhitefoot; panteltje1; edprochak; sudhakar, the
2014-07-01
In reply to the physicsworld.com news story “How to make a quantum random-number generator from a mobile phone” (16 May, http://ow.ly/xFiYc, see also p5), which describes a way of delivering random numbers by counting the number of photons that impinge on each of the individual pixels in the camera of a Nokia N9 smartphone.
Barra, Orazio A
2013-01-01
Although HRV (Heart Rate Variability) analyses have been carried out for several decades, several limiting factors still make these analyses useless from a clinical point of view. The present paper aims at overcoming some of these limits by introducing the "Life Potential" (BMP), a new mathematical algorithm which seems to exhibit surprising cognitive and predictive capabilities. BMP is defined as a linear combination of five HRV Non-Linear Variables, in turn derived from the thermodynamic formalism of chaotic dynamic systems. The paper presents experimental measurements of BMP (Average Values and Standard Deviations) derived from 1048 Holter tests, matched in age and gender, including a control group of 356 healthy subjects. The main results are: (a) BMP always decreases when the age increases, and its dependence on age and gender is well established; (b) the shape of the age dependence within "healthy people" is different from that found in the general group: this behavior provides evidence of possible illn...
张屹尚; 刘永寿; 赵彬; 翟红波
2014-01-01
针对激励与结构参数同时存在不确定性的复合随机振动系统，由随机结构无条件动力可靠度表达式出发，利用条件概率密度函数解析变换给出衡量基本随机变量对动力可靠性影响的矩独立重要性测度指标。该指标可表征不确定性随机变量对动力可靠度响应量分布的平均影响程度，可全面反映随机变量对响应分布影响。基于状态依存参数模型，提出求解矩独立重要性测度指标的态相关参数（SDP）法。利用算例分析结构动力可靠性参数的矩独立重要性测度，并与直接 Monte -Carlo 法对比。所提方法可在保证计算精度同时大幅度提高计算效率，适用于分析复合随机振动系统非线性可靠性响应。%A moment-independent importance measure index of dynamic reliability for double random vibration systems,in which the randomness of structural parameters and excitation was taken into account,was introduced to analyze the effect of input variables on dynamic reliability.Based on the expressions of unconditional dynamic reliability and conditional probability density function (PDF),the importance measure index was numerically obtained.The index can effectively describe the mean effect of the PDF on dynamic reliability from the distribution density of the basic variable.Then,on the basis of the state dependent parameter (SDP)model,the SDP method was established to estimate the defined moment-independent importance measure index.Additionally,two examples were given to illustrate the advantages of the presented method.Comparing with the direct Monte Carlo method,the results show that the established solution can considerably improve computational efficiency with acceptable precision and be suitable for analyzing non-linear dynamic reliability responses of double random vibration systems.
苏淳; 梁汉营; 王岳宝
2000-01-01
Let X1,X2, be independent identicallydistributed (iid) random variables, Un=1 i
Cheng, Yue; Li, Zhuang; Xi, Hualong; Gu, Tiejun; Yuan, Ruosen; Chen, Xiaoxu; Jiang, Chunlai; Kong, Wei; Wu, Yongge
2016-01-01
Lethal rabies can be prevented effectively by post-exposure prophylactic (PEP) with rabies immunoglobulin (RIG). Single-chain variable fragment (scFv), which is composed of a variable heavy chain (VH) and variable light chain (VL) connected by a peptide linker, may be developed as alternative to RIG for neutralizing rabies virus (RV). However, our previously constructed scFv (FV57S) with the (NH2) VH-linker-VL (COOH) orientation showed a lower neutralizing potency than its parent RIG. This orientation may inhibit FV57S from refolding into an intact and correct conformation. Therefore, the RFV57S protein with a VL-linker-VH orientation was constructed based on FV57S. A HIS tag was incorporated to aid in purification and detection of RFV57S and FV57S. However, abilities of RFV57S and FV57S to bind with the anti-HIS tag mAb were different. Therefore, a novel direct ELISA was established by utilizing a biotin-labeled truncated glycoprotein of RV. Although with similar stability and in vitro neutralizing potency as FV57S, RFV57S showed enhanced binding ability, affinity and in vivo protective efficacy against lethal dose of RV. Our studies support the feasibility of developing a scFv with reversed orientation and provide a novel method for evaluating the binding ability, stability and affinity of engineered antibodies recognizing linear epitope.
Buenzli, Esther; Apai, Daniel; Flateau, Davin [Department of Astronomy and Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States); Morley, Caroline V. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, Santa Cruz, CA 95060 (United States); Showman, Adam P.; Lewis, Nikole K. [Department of Planetary Sciences and Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Marley, Mark S. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Reid, I. Neill, E-mail: ebuenzli@email.arizona.edu [Space Telescope Science Institute, Baltimore, MD 21218 (United States)
2012-12-01
Heterogeneous clouds or temperature perturbations in rotating brown dwarfs produce variability in the observed flux. We report time-resolved simultaneous observations of the variable T6.5 brown dwarf 2MASS J22282889-431026 over the wavelength ranges 1.1-1.7 {mu}m and broadband 4.5 {mu}m. Spectroscopic observations were taken with Wide Field Camera 3 on board the Hubble Space Telescope and photometry with the Spitzer Space Telescope. The object shows sinusoidal infrared variability with a period of 1.4 hr at most wavelengths with peak-to-peak amplitudes between 1.45% and 5.3% of the mean flux. While the light curve shapes are similar at all wavelengths, their phases differ from wavelength to wavelength with a maximum difference of more than half of a rotational period. We compare the spectra with atmospheric models of different cloud prescriptions, from which we determine the pressure levels probed at different wavelengths. We find that the phase lag increases with decreasing pressure level, or higher altitude. We discuss a number of plausible scenarios that could cause this trend of light curve phase with probed pressure level. These observations are the first to probe heterogeneity in an ultracool atmosphere in both horizontal and vertical directions, and thus are an ideal test case for realistic three-dimensional simulations of the atmospheric structure with clouds in brown dwarfs and extrasolar planets.
Jhanjee, Sonali; Jain, Raka; Jain, Veena; Gupta, Tina; Mittal, Swati; Goelz, Patricia; Schnoll, Robert A
2015-01-01
This study examined changes in tobacco craving, withdrawal, and affect as correlates of efficacy in a phase-2 clinical trial of varenicline for smokeless tobacco dependence in India. Smokeless tobacco users (N = 237) at the All India Institute of Medical Sciences were randomized to placebo or varenicline. Abstinence was defined as cotinine-verified seven-day point prevalence cessation at end of treatment (EOT). General Linear Model repeated measures assessed the effects of treatment condition, time, abstinence state, and interaction effects on changes in craving, withdrawal, positive (PA) and negative affect (NA) from baseline to EOT. All participants showed a significant reduction in withdrawal (p positive reinforcement (PR) craving (p vs. those still chewing smokeless tobacco. Additional research is needed concerning the effects of varenicline on craving, withdrawal, and affect among smokeless tobacco users.
Random trinomial tree models and vanilla options
Ganikhodjaev, Nasir; Bayram, Kamola
2013-09-01
In this paper we introduce and study random trinomial model. The usual trinomial model is prescribed by triple of numbers (u, d, m). We call the triple (u, d, m) an environment of the trinomial model. A triple (Un, Dn, Mn), where {Un}, {Dn} and {Mn} are the sequences of independent, identically distributed random variables with 0 < Dn < 1 < Un and Mn = 1 for all n, is called a random environment and trinomial tree model with random environment is called random trinomial model. The random trinomial model is considered to produce more accurate results than the random binomial model or usual trinomial model.
Angular processes related to Cauchy random walks
Cammarota, Valemtina
2011-01-01
We study the angular process related to random walks in the Euclidean and in the non-Euclidean space where steps are Cauchy distributed. This leads to different types of non-linear transformations of Cauchy random variables which preserve the Cauchy density. We give the explicit form of these distributions for all combinations of the scale and the location parameters. Continued fractions involving Cauchy random variables are analyzed. It is shown that the $n$-stage random variables are still Cauchy distributed with parameters related to Fibonacci numbers. This permits us to show the convergence in distribution of the sequence to the golden ratio.
Clément Palpacuer
2015-12-01
Full Text Available Nalmefene is a recent option in alcohol dependence treatment. Its approval was controversial. We conducted a systematic review and meta-analysis of the aggregated data (registered as PROSPERO 2014:CRD42014014853 to compare the harm/benefit of nalmefene versus placebo or active comparator in this indication.Three reviewers searched for published and unpublished studies in Medline, the Cochrane Library, Embase, ClinicalTrials.gov, Current Controlled Trials, and bibliographies and by mailing pharmaceutical companies, the European Medicines Agency (EMA, and the US Food and Drug Administration. Double-blind randomized clinical trials evaluating nalmefene to treat adult alcohol dependence, irrespective of the comparator, were included if they reported (1 health outcomes (mortality, accidents/injuries, quality of life, somatic complications, (2 alcohol consumption outcomes, (3 biological outcomes, or (4 treatment safety outcomes, at 6 mo and/or 1 y. Three authors independently screened the titles and abstracts of the trials identified. Relevant trials were evaluated in full text. The reviewers independently assessed the included trials for methodological quality using the Cochrane Collaboration tool for assessing risk of bias. On the basis of the I2 index or the Cochrane's Q test, fixed or random effect models were used to estimate risk ratios (RRs, mean differences (MDs, or standardized mean differences (SMDs with 95% CIs. In sensitivity analyses, outcomes for participants who were lost to follow-up were included using baseline observation carried forward (BOCF; for binary measures, patients lost to follow-up were considered equal to failures (i.e., non-assessed patients were recorded as not having responded in both groups. Five randomized controlled trials (RCTs versus placebo, with a total of 2,567 randomized participants, were included in the main analysis. None of these studies was performed in the specific population defined by the EMA approval
CARR,ROBERT D.; VEMPALA,SANTOSH
2000-01-25
The authors present a new technique for the design of approximation algorithms that can be viewed as a generalization of randomized rounding. They derive new or improved approximation guarantees for a class of generalized congestion problems such as multicast congestion, multiple TSP etc. Their main mathematical tool is a structural decomposition theorem related to the integrality gap of a relaxation.
Nevin, J A; Randolph; Holland, S; McLean, A P
2001-07-01
Two experiments asked whether resistance to change depended on variable-ratio as opposed to variable-interval contingencies of reinforcement and the different response rates they establish. In Experiment 1, pigeons were trained on multiple random-ratio random-interval schedules with equated reinforcer rates. Baseline response rates were disrupted by intercomponent food, extinction, and prefeeding. Resistance to change relative to baseline was greater in the interval component, and the difference was correlated with the extent to which baseline response rates were higher in the ratio component. In Experiment 2, pigeons were trained on multiple variable-ratio variable-interval schedules in one half of each session and on concurrent chains in the other half in which the terminal links corresponded to the multiple-schedule components. The schedules were varied over six conditions, including two with equated reinforcer rates. In concurrent chains, preference strongly overmatched the ratio of obtained reinforcer rates. In multiple schedules, relative resistance to response-independent food during intercomponent intervals, extinction, and intercomponent food plus extinction depended on the ratio of obtained reinforcer rates but was less sensitive than was preference. When reinforcer rates were similar, both preference and relative resistance were greater for the variable-interval schedule, and the differences were correlated with the extent to which baseline response rates were higher on the variable-ratio schedule, confirming the results of Experiment 1. These results demonstrate that resistance to change and preference depend in part on response rate as well as obtained reinforcer rate, and challenge the independence of resistance to change and preference with respect to response rate proposed by behavioral momentum theory.
Palacios, C.; Abecia, J. A.
2015-05-01
A total number of 48,088 artificial inseminations (AIs) have been controlled during seven consecutive years in 79 dairy sheep Spanish farms (41° N). Mean, maximum and minimum ambient temperatures ( Ts), temperature amplitude (TA), mean relative humidity (RH), mean solar radiation (SR) and total rainfall of each insemination day and 15 days later were recorded. Temperature-humidity index (THI) and effective temperature (ET) have been calculated. A binary logistic regression model to estimate the risk of not getting pregnant compared to getting pregnant, through the odds ratio (OR), was performed. Successful winter inseminations were carried out under higher SR ( P 1 (maximum T, ET and rainfall on AI day, and ET and rainfall on day 15), and two variables presented OR reverse their effects in the hot or cold seasons. A forecast of the meteorological conditions could be a useful tool when AI dates are being scheduled.
Multiple-support seismic response of Bosporus Suspension Bridge for various random vibration methods
Süleyman Adanur
2016-06-01
Full Text Available This paper presents a study about the spatial variability effects of ground motions on the dynamic behavior of a suspension bridge by a random vibration based spectral analysis approach and two response spectrum methods. Bosphorus Suspension Bridge built in Turkey and connects Europe to Asia in Istanbul is selected as a numerical example. The spatial variability of ground motions between the support points is taken into account with a coherency function that characterizes the incoherence, wave-passage and site-response effects. Power spectral density function and response spectrum values used in random vibration analyses are determined depending on the recordings of August 17, 1999, Kocaeli, Turkey earthquake. From the results, it can be observed that the structural responses for each random vibration analysis depend largely on the intensity and frequency contents of power spectral density functions.
Random discrete Schroedinger operators from random matrix theory
Breuer, Jonathan [Institute of Mathematics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Forrester, Peter J [Department of Mathematics and Statistics, University of Melbourne, Parkville, Vic 3010 (Australia); Smilansky, Uzy [Department of Physics of Complex Systems, Weizmann Institute, Rehovot 76100 (Israel)
2007-02-02
We investigate random, discrete Schroedinger operators which arise naturally in the theory of random matrices, and depend parametrically on Dyson's Coulomb gas inverse temperature {beta}. They are similar to the class of 'critical' random Schroedinger operators with random potentials which diminish as vertical bar x vertical bar{sup -1/2}. We show that as a function of {beta} they undergo a transition from a regime of (power-law) localized eigenstates with a pure point spectrum for {beta} < 2 to a regime of extended states with a singular continuous spectrum for {beta} {>=} 2. (fast track communication)
Ayşe Binnur Erbağci
1999-01-01
Full Text Available Information on menstrual cycle dependent variation of tumor markers in healthy women is a subject of diagnostic efficiency and has an impact in elucidating the normal function of these markers. In this study midfollicular and midluteal concentrations of serum CEA, AFP, CA 19-9, CA 125, CA 15-3 and their relations with LH, FSH, prolactin, estradiol and progesterone were evaluated during ovulatory cycles in a group of 23 healthy female individuals. Samples were collected on the 7th and 21st day of the same menstrual cycle. Tumor marker and hormone concentrations were determined with chemiluminescence or electrochemiluminescence EIA methods. A significant phase-dependent difference was observed for CA 15-3, midluteal concentrations (mean ± SEM; 26.33 ± 1.56 U/ml higher than the midfollicular (mean ± SEM; 19.27 ± 1.49 U/ml concentrations (p < 0.001. But an obvious difference for other tumor markers investigated did not exist. Significant correlations of follicular and luteal CA 125 levels with body mass index of the subjects were observed (r:0.52, p < 0.05 and r:0.57, p < 0.005, respectively.
Poutanen, Juri; Ibragimov, Askar
2008-01-01
We discover a pronounced dependence of the strength of the soft X-ray orbital modulation in Cyg X-1 in the hard state on its superorbital phase. We find our results can be well modelled as orbital-phase dependent X-ray absorption in an accretion bulge, located at the accretion disc edge close to the companion but displaced from the line connecting the stars by about 25^o and in the case when the disc is precessing (which appears to cause the superorbital flux modulation). Our finding are supported by the distribution of the X-ray dips showing concentration towards zero superorbital phase, which corresponds to the bulge passing through the line of sight. We Fourier analyse our model, and find it explains the previous finding of asymmetric beat (between the orbital and superorbital modulations) frequencies in the observed power spectrum, provided the disc precession is prograde. On the other hand, we find no statistically significant changes of the orbital modulation with the superorbital phase in the 15-GHz ra...
Reactive particles in random flows.
Károlyi, György; Tél, Tamás; de Moura, Alessandro P S; Grebogi, Celso
2004-04-30
We study the dynamics of chemically or biologically active particles advected by open flows of chaotic time dependence, which can be modeled by a random time dependence of the parameters on a stroboscopic map. We develop a general theory for reactions in such random flows, and derive the reaction equation for this case. We show that there is a singular enhancement of the reaction in random flows, and this enhancement is increased as compared to the nonrandom case. We verify our theory in a model flow generated by four point vortices moving chaotically.