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.
Simple dependent pairs of exponential and uniform random variables
A. J. Lawrance; Lewis, Peter Adrian Walter
1982-01-01
A random-coefficient linear function of two independent exponential variables yielding a third exponential variable is used in the construction of simple, dependent pairs of exponential variables. By employing antithetic exponential variables, the constructions are developed to encompass negative dependency. By employing negative exponentiation, the constructions yield simple multiplicative-based models for dependent uniform pairs. The ranges of dependency allowable in the models are assessed...
LARGE DEVIATIONS AND MODERATE DEVIATIONS FOR SUMS OF NEGATIVELY DEPENDENT RANDOM VARIABLES
Institute of Scientific and Technical Information of China (English)
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
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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.
Directory of Open Access Journals (Sweden)
Yongfeng Wu
2014-01-01
Full Text Available The authors first present a Rosenthal inequality for sequence of extended negatively dependent (END random variables. By means of the Rosenthal inequality, the authors obtain some complete moment convergence and mean convergence results for arrays of rowwise END random variables. The results in this paper extend and improve the corresponding theorems by Hu and Taylor (1997.
Institute of Scientific and Technical Information of China (English)
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
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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.
Non-uniform approximations for sums of discrete m-dependent random variables
Vellaisamy, P.; Cekanavicius, V.
2013-01-01
Non-uniform estimates are obtained for Poisson, compound Poisson, translated Poisson, negative binomial and binomial approximations to sums of of m-dependent integer-valued random variables. Estimates for Wasserstein metric also follow easily from our results. The results are then exemplified by the approximation of Poisson binomial distribution, 2-runs and $m$-dependent $(k_1,k_2)$-events.
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
Asymptotic Results for Tail Probabilities of Sums of Dependent and Heavy-Tailed Random Variables
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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
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PAN; Jiazhu(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
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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.
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.
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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
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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
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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.
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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.
Barcella, William; Iorio, Maria De; Baio, Gianluca; Malone-Lee, James
2016-04-15
Lower urinary tract symptoms can indicate the presence of urinary tract infection (UTI), a condition that if it becomes chronic requires expensive and time consuming care as well as leading to reduced quality of life. Detecting the presence and gravity of an infection from the earliest symptoms is then highly valuable. Typically, white blood cell (WBC) count measured in a sample of urine is used to assess UTI. We consider clinical data from 1341 patients in their first visit in which UTI (i.e. WBC ≥ 1) is diagnosed. In addition, for each patient, a clinical profile of 34 symptoms was recorded. In this paper, we propose a Bayesian nonparametric regression model based on the Dirichlet process prior aimed at providing the clinicians with a meaningful clustering of the patients based on both the WBC (response variable) and possible patterns within the symptoms profiles (covariates). This is achieved by assuming a probability model for the symptoms as well as for the response variable. To identify the symptoms most associated to UTI, we specify a spike and slab base measure for the regression coefficients: this induces dependence of symptoms selection on cluster assignment. Posterior inference is performed through Markov Chain Monte Carlo methods. PMID:26536840
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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
DEFF Research Database (Denmark)
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
Institute of Scientific and Technical Information of China (English)
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.
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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.
Symmetrization of binary random variables
Kagan, Abram; Mallows, Colin L.; Shepp, Larry A.; Vanderbei, Robert J.; Vardi, Yehuda
1999-01-01
A random variable [math] is called an independent symmetrizer of a given random variable [math] if (a) it is independent of [math] and (b) the distribution of [math] is symmetric about [math] . In cases where the distribution of [math] is symmetric about its mean, it is easy to see that the constant random variable [math] is a minimum-variance independent symmetrizer. Taking [math] to have the same distribution as [math] clearly produces a symmetric sum, but it may not be of minimum variance....
Complete Convergence for Weighted Sums of WOD Random Variables
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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.
On Sums of Conditionally Independent Subexponential Random Variables
Foss, Serguei; Richards, Andrew
2008-01-01
The asymptotic tail behaviour of sums of independent subexponential random variables is well understood, one of the main characteristics being the principle of the single big jump. We study the case of dependent subexponential random variables, for both deterministic and random sums, using a fresh approach, by considering conditional independence structures on the random variables. We seek sufficient conditions for the results of the theory with independent random variables still to hold. For...
Contextuality is about identity of random variables
Dzhafarov, Ehtibar N.; Kujala, Janne V.
2014-12-01
Contextual situations are those in which seemingly ‘the same’ random variable changes its identity depending on the conditions under which it is recorded. Such a change of identity is observed whenever the assumption that the variable is one and the same under different conditions leads to contradictions when one considers its joint distribution with other random variables (this is the essence of all Bell-type theorems). In our Contextuality-by-Default approach, instead of asking why or how the conditions force ‘one and the same’ random variable to change ‘its’ identity, any two random variables recorded under different conditions are considered different ‘automatically.’ They are never the same, nor are they jointly distributed, but one can always impose on them a joint distribution (probabilistic coupling). The special situations when there is a coupling in which these random variables are equal with probability 1 are considered noncontextual. Contextuality means that such couplings do not exist. We argue that the determination of the identity of random variables by conditions under which they are recorded is not a causal relationship and cannot violate laws of physics.
RANDOM VARIABLE WITH FUZZY PROBABILITY
Institute of Scientific and Technical Information of China (English)
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.
A Measure of Monotonicity of two Random Variables
Ilias Kachapov; Farida Kachapova
2012-01-01
Problem statement: When analyzing random variables it was useful to measure the degree of their monotone dependence or compare pairs of random variables with respect to their monotonicity. Existing coefficients measure general or linear dependence of random variables. Developing a measure of monotonicity was useful for practical applications as well as for general theory, since monotonicity was an important type of dependence. Approach: Existing measures of dependence are briefly reviewed. Th...
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De Mei YUAN; Jun AN
2012-01-01
Both residual Cesàro alpha-integrability (RCI(α)) and strongly residual Cesàro alphaintegrability (SRCI(α)) are two special kinds of extensions to uniform integrability,and both asymptotically almost negative association (AANA) and asymptotically quadrant sub-independence (AQSI)are two special kinds of dependence structures.By relating the RCI(α) property as well as the SRCI(α)property with dependence condition AANA or AQSI,we formulate some tail-integrability conditions under which for appropriate α the RCI(α) property yields L1-convergence results and the SRCI(α)property yields strong laws of large numbers,which is the continuation of the corresponding literature.
Randomness and Earth climate variability
Levinshtein, Michael E; Dmitriev, Alexander P; Shmakov, Pavel M
2015-01-01
Paleo-Sciences including palaeoclimatology and palaeoecology have accumulated numerous records related to climatic changes. The researchers have usually tried to identify periodic and quasi-periodic processes in these paleoscientific records. In this paper, we show that this analysis is incomplete. As follows from our results, random processes, namely processes with a single-time-constant (noise with a Lorentzian noise spectrum), play a very important and, perhaps, a decisive role in numerous natural phenomena. For several of very important natural phenomena the characteristic time constants are very similar and equal to (5-8)x10^3 years. However, this value is not universal. For example, the spectral density fluctuations of the atmospheric radiocarbon 14C are characterized by a Lorentzian with time constant 300 years. The frequency dependence of spectral density fluctuations for benthic 18O records contains two Lorentzians with time constans 8000 years and > 105 years.
APPROXIMATION OF RANDOM SUMS OF RANDOM VARIABLES IN INSURANCE
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Paweł Wlaź
2014-09-01
Full Text Available The paper deals with approximations of random sums. By random sum we mean a sum of random number of independent and identically distributed random variables. Distribution of this sum is called a compound distribution. The model is especially important in non-life insurance. There are many methods for approximating compound distributions, one of the most popular one is approximation with shifted gamma distribution. In this work we show an alternative way – using kernel density, Fast Fourier Transform and numerical optimization methods – for finding shifted gamma approximations and show results suggesting its superiority over classical method.
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
Conditional variable importance for random forests
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Augustin Thomas
2008-07-01
Full Text Available Abstract Background Random forests are becoming increasingly popular in many scientific fields because they can cope with "small n large p" problems, complex interactions and even highly correlated predictor variables. Their variable importance measures have recently been suggested as screening tools for, e.g., gene expression studies. However, these variable importance measures show a bias towards correlated predictor variables. Results We identify two mechanisms responsible for this finding: (i A preference for the selection of correlated predictors in the tree building process and (ii an additional advantage for correlated predictor variables induced by the unconditional permutation scheme that is employed in the computation of the variable importance measure. Based on these considerations we develop a new, conditional permutation scheme for the computation of the variable importance measure. Conclusion The resulting conditional variable importance reflects the true impact of each predictor variable more reliably than the original marginal approach.
Delocalization for Random Landau Hamiltonians with Unbounded Random Variables
Germinet, François; Mandy, Benoît
2009-01-01
In this note we prove the existence of a localization/delocalization transition for Landau Hamiltonians randomly perturbed by an electric potential with unbounded amplitude. In particular, with probability one, no Landau gaps survive as the random potential is turned on, the gaps close, filling up partly with localized states. A minimal rate of transport is exhibited in the region of delocalization. To do so, we exploit the a priori quantization of the Hall conductance and extend recent Wegner estimates to the case of unbounded random variables.
Polynomial chaos expansion with random and fuzzy variables
Jacquelin, E.; Friswell, M. I.; Adhikari, S.; Dessombz, O.; Sinou, J.-J.
2016-06-01
A dynamical uncertain system is studied in this paper. Two kinds of uncertainties are addressed, where the uncertain parameters are described through random variables and/or fuzzy variables. A general framework is proposed to deal with both kinds of uncertainty using a polynomial chaos expansion (PCE). It is shown that fuzzy variables may be expanded in terms of polynomial chaos when Legendre polynomials are used. The components of the PCE are a solution of an equation that does not depend on the nature of uncertainty. Once this equation is solved, the post-processing of the data gives the moments of the random response when the uncertainties are random or gives the response interval when the variables are fuzzy. With the PCE approach, it is also possible to deal with mixed uncertainty, when some parameters are random and others are fuzzy. The results provide a fuzzy description of the response statistical moments.
Reduction of the Random Variables of the Turbulent Wind Field
DEFF Research Database (Denmark)
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
Institute of Scientific and Technical Information of China (English)
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.
Product of n independent uniform random variables
Dettmann, Carl P.; Georgiou, Orestis
2009-01-01
Abstract We give an alternative proof of a useful formula for calculating the probability density function of the product of n uniform, independently and identically distributed random variables. Ishihara (2002, in Japanese) proves the result by induction; here we use Fourier analysis and contour integral methods which provide a more intuitive explanation of how the convolution theorem acts in this case. correspondance: Corresponding author. ...
LARGE DEVIATIONS AND MODERATE DEVIATIONS FOR m-NEGATIVELY ASSOCIATED RANDOM VARIABLES
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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.
Inequalities for Walsh like random variables
D. Hajela
1990-01-01
Let (Xn)nÃ¢Â‰Â¥1 be a sequence of mean zero independent random variables. Let Wk={Ã¢ÂˆÂj=1kXij|1Ã¢Â‰Â¤i10 and let C(p,m)=16(52p2pÃ¢ÂˆÂ’1)mÃ¢ÂˆÂ’1plogp(KÃŽÂ´)m for 1
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
Institute of Scientific and Technical Information of China (English)
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
Directory of Open Access Journals (Sweden)
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
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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.
Summability of Double Independent Random Variables
Ekrem Savaş; Richard F. Patterson
2008-01-01
We will examine double sequence to double sequence transformation of independent identically distribution random variables with respect to four-dimensional summability matrix methods. The main goal of this paper is the presentation of the following theorem. If maxÃ¢ÂÂ¡k,l|am,n,k,l|=maxÃ¢ÂÂ¡k,l|am,kan,l|=O(mÃ¢ÂˆÂ’ÃŽÂ³1)O(nÃ¢ÂˆÂ’ÃŽÂ³2), ÃŽÂ³1,ÃŽÂ³2>0, then E|XÃ¢ÂŒÂ£|1+1/ÃŽÂ³1
Summability of Double Independent Random Variables
Directory of Open Access Journals (Sweden)
Ekrem Savaş
2008-09-01
Full Text Available We will examine double sequence to double sequence transformation of independent identically distribution random variables with respect to four-dimensional summability matrix methods. The main goal of this paper is the presentation of the following theorem. If maxÃ¢ÂÂ¡k,l|am,n,k,l|=maxÃ¢ÂÂ¡k,l|am,kan,l|=O(mÃ¢ÂˆÂ’ÃŽÂ³1O(nÃ¢ÂˆÂ’ÃŽÂ³2, ÃŽÂ³1,ÃŽÂ³2>0, then E|XÃ¢ÂŒÂ£|1+1/ÃŽÂ³1<Ã¢ÂˆÂž and E|XÃ¢ÂŒÂ£Ã¢ÂŒÂ£|1+1/ÃŽÂ³2<Ã¢ÂˆÂž imply that Ym,nÃ¢Â†Â’ÃŽÂ¼ almost sure P-convergence.
Almost Sure Convergence Theorem and Strong Stability for Weighted Sums of NSD Random Variables
Institute of Scientific and Technical Information of China (English)
Yan SHEN; Xue Jun WANG; Wen Zhi YANG; Shu He HU
2013-01-01
In this paper,Kolmogorov-type inequality for negatively superadditive dependent (NSD)random variables is established.By using this inequality,we obtain the almost sure convergence for NSD sequences,which extends the corresponding results for independent sequences and negatively associated (NA) sequences.In addition,the strong stability for weighted sums of NSD random variables is studied.
Moment inequalities for the partial sums of random variables
Institute of Scientific and Technical Information of China (English)
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
Institute of Scientific and Technical Information of China (English)
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
Environment-dependent continuous time random walk
Institute of Scientific and Technical Information of China (English)
Lin Fang; Bao Jing-Dong
2011-01-01
A generalized continuous time random walk model which is dependent on environmental damping is proposed in which the two key parameters of the usual random walk theory:the jumping distance and the waiting time, are replaced by two new ones:the pulse velocity and the flight time. The anomalous diffusion of a free particle which is characterized by the asymptotical mean square displacement ～tα is realized numerically and analysed theoretically, where the value of the power index a is in a region of 0<α<2. Particularly, the damping leads to a sub-diffusion when the impact velocities are drawn from a Gaussian density function and the super-diffusive effect is related to statistical extremes, which are called rare-though-dominant events.
Communication Requirements for Generating Correlated Random Variables
Cuff, Paul
2008-01-01
Two familiar notions of correlation are rediscovered as extreme operating points for simulating a discrete memoryless channel, in which a channel output is generated based only on a description of the channel input. Wyner's "common information" coincides with the minimum description rate needed. However, when common randomness independent of the input is available, the necessary description rate reduces to Shannon's mutual information. This work characterizes the optimal tradeoff between the amount of common randomness used and the required rate of description.
On the product and ratio of Bessel random variables
Directory of Open Access Journals (Sweden)
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.
An Inequality for the Sum of Independent Bounded Random Variables
Dance, Christopher R.
2012-01-01
We give a simple inequality for the sum of independent bounded random variables. This inequality improves on the celebrated result of Hoeffding in a special case. It is optimal in the limit where the sum tends to a Poisson random variable.
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
SOME LIMIT THEOREMS FOR SEQUENCES OF PAIRWISE NQD RANDOM VARIABLES
Institute of Scientific and Technical Information of China (English)
Gan Shixin; Chen Pingyan
2008-01-01
In this article, the authors study some limit properties for sequences of pair- wise NQD random variables, which are not necessarily identically distributed. They obtain Baum and Katz complete convergence and the strong stability of Jamison's weighted sums for pairwise NQD random variables, which may have different distributions. Some well- known results are improved and extended.
Moment inequalities for the partial sums of random variables
Institute of Scientific and Technical Information of China (English)
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.
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.
On the minimum of independent geometrically distributed random variables
Ciardo, Gianfranco; Leemis, Lawrence M.; Nicol, David
1994-01-01
The expectations E(X(sub 1)), E(Z(sub 1)), and E(Y(sub 1)) of the minimum of n independent geometric, modifies geometric, or exponential random variables with matching expectations differ. We show how this is accounted for by stochastic variability and how E(X(sub 1))/E(Y(sub 1)) equals the expected number of ties at the minimum for the geometric random variables. We then introduce the 'shifted geometric distribution' and show that there is a unique value of the shift for which the individual shifted geometric and exponential random variables match expectations both individually and in the minimums.
Cardinality-dependent Variability in Orthogonal Variability Models
DEFF Research Database (Denmark)
Mærsk-Møller, Hans Martin; Jørgensen, Bo Nørregaard
2012-01-01
by the specific variants being bound, but by their sheer numbers. This paper contributes with an extension to the meta-model underlying the OVM notation, suggesting a notation for the new type of dependency and shows its applicability. The specific case, which initially required this extension, will work......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 cardinality range dependencies. The cardinality-range-dependency type enables expressing that the binding of a certain number of variants to a variation point can influence variability in other places in the model. In other words, we acknowledge that variability can be influenced, not necessarily...
Central limit theorem for a class of globally correlated random variables
Budini, Adrián A.
2016-06-01
The standard central limit theorem with a Gaussian attractor for the sum of independent random variables may lose its validity in the presence of strong correlations between the added random contributions. Here, we study this problem for similar interchangeable globally correlated random variables. Under these conditions, a hierarchical set of equations is derived for the conditional transition probabilities. This result allows us to define different classes of memory mechanisms that depend on a symmetric way on all involved variables. Depending on the correlation mechanisms and statistics of the single variables, the corresponding sums are characterized by distinct probability densities. For a class of urn models it is also possible to characterize their domain of attraction, which, as in the standard case, is parametrized by the probability density of each random variable. Symmetric and asymmetric q -Gaussian attractors (q <1 ) arise in a particular two-state case of these urn models.
Randomly weighted sums of subexponential random variables with application to ruin theory
Q. Tang; G. Tsitsiashvili
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 (
Randomly weighted sums of subexponential random variables with application to ruin theory
Q. Tang; G.Sh. Tsitsiashvili
2004-01-01
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 (
Institute of Scientific and Technical Information of China (English)
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.
Designing neural networks that process mean values of random variables
Energy Technology Data Exchange (ETDEWEB)
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.
Limiting Behavior of Weighted Sums of NOD Random Variables
Institute of Scientific and Technical Information of China (English)
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.
Exponential Inequalities for Positively Associated Random Variables and Applications
Directory of Open Access Journals (Sweden)
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.
Random Forests for Ordinal Response Data: Prediction and Variable Selection
Janitza, Silke; Tutz, Gerhard; Boulesteix, Anne-Laure
2014-01-01
The random forest method is a commonly used tool for classification with high-dimensional data that is able to rank candidate predictors through its inbuilt variable importance measures (VIMs). It can be applied to various kinds of regression problems including nominal, metric and survival response variables. While classification and regression problems using random forest methodology have been extensively investigated in the past, there seems to be a lack of literature on handling ordinal re...
Some Limit Theorems for Negatively Associated Random Variables
Indian Academy of Sciences (India)
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.
Problems Identifying Independent and Dependent Variables
Leatham, Keith R.
2012-01-01
This paper discusses one step from the scientific method--that of identifying independent and dependent variables--from both scientific and mathematical perspectives. It begins by analyzing an episode from a middle school mathematics classroom that illustrates the need for students and teachers alike to develop a robust understanding of…
PaCAL: A Python Package for Arithmetic Computations with Random Variables
Directory of Open Access Journals (Sweden)
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.
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.
Random Time Dependent Resistance Analysis on Reinforced Concrete Structures
Institute of Scientific and Technical Information of China (English)
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.
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.
Age-dependent branching processes in random environments
Institute of Scientific and Technical Information of China (English)
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
Institute of Scientific and Technical Information of China (English)
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.
Repeated Sprints: An Independent Not Dependent Variable.
Taylor, Jonathan M; Macpherson, Tom W; Spears, Iain R; Weston, Matthew
2016-07-01
The ability to repeatedly perform sprints has traditionally been viewed as a key performance measure in team sports, and the relationship between repeated-sprint ability (RSA) and performance has been explored extensively. However, when reviewing the repeated-sprint profile of team-sports match play it appears that the occurrence of repeated-sprint bouts is sparse, indicating that RSA is not as important to performance as commonly believed. Repeated sprints are, however, a potent and time-efficient training strategy, effective in developing acceleration, speed, explosive leg power, aerobic power, and high-intensity-running performance--all of which are crucial to team-sport performance. As such, we propose that repeated-sprint exercise in team sports should be viewed as an independent variable (eg, a means of developing fitness) as opposed to a dependent variable (eg, a means of assessing fitness/performance). PMID:27197118
Some Limit Theorems for Weighted Sums of Random Variable Fields
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Let{X-n,-n∈Nd} be a field of Banach space valued random variables, 0 ＜r＜p≤2 and{a-n,-k,(-n,-k)∈Nd×Nd,-k≤-n} a triangular array of real numbers, where Nd is the d-dimensional lattice(d≥1). Under the minimal condition that {‖X-n‖r,-n∈Nd} is {|a-n,-k|r,(-n,-k)} ∈Nd×Nd,-k≤-n}-uniformly integrable, we show that ∑(-k≤-n)(a-n,-kX-k)Lr(or a.s.)→0 as |-n|→∞. In the above, if 0＜r＜1, the random variables are not needed to be independent. If 1≤r＜p≤2, and Banach space valued random variables are independent with mean zero we assume the Banach space is of type p. If 1≤r＜p≤2 and Banach space valued random variables are not independent we assume the Banach space is p-smoothable.
Tail distribution of the maximum of correlated gaussian random variables
Z.I. Botev; M. Mandjes; A. Ridder
2015-01-01
In this article we consider the efficient estimation of the tail distribution of the maximum of correlated normal random variables. We show that the currently recommended Monte Carlo estimator has difficulties in quantifying its precision, because its sample variance estimator is an inefficient esti
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 ...
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.
Problems of variance reduction in the simulation of random variables
International Nuclear Information System (INIS)
The definition of the uniform linear generator is given and some of the mostly used tests to evaluate the uniformity and the independence of the obtained determinations are listed. The problem of calculating, through simulation, some moment W of a random variable function is taken into account. The Monte Carlo method enables the moment W to be estimated and the estimator variance to be obtained. Some techniques for the construction of other estimators of W with a reduced variance are introduced
Shape and distribution of Jones and Faddy's skew t random variable
Directory of Open Access Journals (Sweden)
Saipornchai, N.
2005-09-01
Full Text Available The purpose of this research is to find another way to generate Jones and Faddy's skew t random variable and to construct quantile table, coefficient of skewness, coefficient of kurtosis and coefficient of variation tables of Jones and Faddy's skew t distribution. Graphs of its probability density function and graphs of its distribution function are also presented. The results of this study show that Jones and Faddy's skew t random variable can be generated from a beta random variable on (-1,1. The coefficients of skewness and kurtosis of the distribution depend on parameters a and b. The coefficient of variation of Jones and Faddy's skew t distribution can be calculated.
On the behavior of the product of independent random variables
Institute of Scientific and Technical Information of China (English)
无
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.
Partial summations of stationary sequences of non-Gaussian random variables
DEFF Research Database (Denmark)
Mohr, Gunnar; Ditlevsen, Ove Dalager
1996-01-01
The distribution of the sum of a finite number of identically distributed random variables is in many cases easily determined given that the variables are independent. The moments of any order of the sum can always be expressed by the moments of the single term without computational problems...... lognormal variables or polynomials of standard Gaussian variables. The dependency structure is induced by specifying the autocorrelation structure of the sequence of standard Gaussian variables. Particularly useful polynomials are the Winterstein approximations that distributionally fit with non......-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 are...
Moderate Deviations for Random Sums of Heavy-Tailed Random Variables
Institute of Scientific and Technical Information of China (English)
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.
Casabán, M.-C.; Cortés, J.-C.; Romero, J.-V.; Roselló, M.-D.
2015-07-01
This paper presents a full probabilistic description of the solution of random SI-type epidemiological models which are based on nonlinear differential equations. This description consists of determining: the first probability density function of the solution in terms of the density functions of the diffusion coefficient and the initial condition, which are assumed to be independent random variables; the expectation and variance functions of the solution as well as confidence intervals and, finally, the distribution of time until a given proportion of susceptibles remains in the population. The obtained formulas are general since they are valid regardless the probability distributions assigned to the random inputs. We also present a pair of illustrative examples including in one of them the application of the theoretical results to model the diffusion of a technology using real data.
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
Directory of Open Access Journals (Sweden)
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.
Moment Estimation Inequalities Based on gλ Random Variable on Sugeno Measure Space
Jingfeng Tian; Zhiming Zhang; Dazeng Tian
2010-01-01
The definitions and properties of moment of gλ random variable are provided on Sugeno measure space. Then some important moment estimation inequalities based on gλ random variable are presented and proven.
Strong Law of Large Numb ers for Array of Rowwise AANA Random Variables
Institute of Scientific and Technical Information of China (English)
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.
Separation of Variable Treatment for Solving Time—Dependent Potentials
Institute of Scientific and Technical Information of China (English)
QIANShang－Wu; GUZhi－Yu; 等
2001-01-01
We use the separation of variable treatment to treat some time-dependent systems,and point out that the condition of separability is the same as the condition of existence of invariant,and the separation of variable treatment is interrelated with the quantum-invariant method and the propagator method.We directly use the separation of variable treatment to obtain the wavefunctions of the time-dependent Coulomb potential and the time-dependent Hulthen potential.
Regressor and random-effects dependencies in multilevel models
Ebbes, P.; Bockenholt, U; Wedel, M.
2004-01-01
The objectives of this paper are (1) to review methods that can be used to test for different types of random effects and regressor dependencies, (2) to present results from Monte Carlo studies designed to investigate the performance of these methods, and (3) to discuss estimation methods that can b
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.
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...
Nimon, Kim; Henson, Robin K.
2015-01-01
The authors empirically examined whether the validity of a residualized dependent variable after covariance adjustment is comparable to that of the original variable of interest. When variance of a dependent variable is removed as a result of one or more covariates, the residual variance may not reflect the same meaning. Using the pretest-posttest…
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...
Institute of Scientific and Technical Information of China (English)
刘华汉; 蒋玮; 杨光辉; 吕海霆
2015-01-01
The single mode reliability of the mechanical component is studied with dependent random variables which do not obey the normal distribution.The non-normal distribution random variables are transformed into the normal distribution random variables by using the Rosenblatt transformation (RT),R-F transformation and Edgeworth method.The correlation standard normal random variables are changed into the independent variables on the basis of the linear algebra theory.Then,the single mode reliability index and reliability of mechanical components are obtained by using the first-order second-moment (FOSM)method and advanced first-order second-moment (AFOSM)method.On the basis of the non-normal distribution random variables and the correlation of the variables,computer realization of the reliability calculation algorithm of the mechanical component with single failure mode is proposed.A pair of spur gear in 1 .6 MW wind turbine gearbox is taken as an example with considering one failure mode — tooth surface contact fatigue failure,the effect of the variables' correlation coefficient on the component reliability is analyzed.The high efficiency and applicability of the algorithm are also verified by the example.%研究含有非正态随机变量且随机变量具有相关性的机械零件单模可靠度统一模型，运用 Rosenblatt变换(RT变换)、R-F变换、Edgeworth级数法将非正态分布随机变量变换为正态随机变量，利用线性代数理论将相关标准正态随机变量转换为线性无关的正态随机变量，然后利用一次二阶矩(FOSM)法、改进的一次二阶矩(AFOSM)法求得机械零件单模可靠度指数及可靠度.基于所建机械零件单模可靠度统一模型，提出了含有非正态随机变量且随机变量间具有相关性的零件单模可靠度计算机求解的实现算法.以某1.6 MW风电齿轮箱中一对标准直齿轮啮合传动为例，通过探讨齿面接触疲劳这一单模失效下的可靠度
Warech, E. J.
1967-01-01
Computer program finds values of independent variables which minimize the dependent variable. This optimization program has been used on the F-1 and J-2 engine programs to establish minimum film coolant requirements.
Generalized linear models for categorical and continuous limited dependent variables
Smithson, Michael
2013-01-01
Introduction and OverviewThe Nature of Limited Dependent VariablesOverview of GLMsEstimation Methods and Model EvaluationOrganization of This BookDiscrete VariablesBinary VariablesLogistic RegressionThe Binomial GLMEstimation Methods and IssuesAnalyses in R and StataExercisesNominal Polytomous VariablesMultinomial Logit ModelConditional Logit and Choice ModelsMultinomial Processing Tree ModelsEstimation Methods and Model EvaluationAnalyses in R and StataExercisesOrdinal Categorical VariablesModeling Ordinal Variables: Common Practice versus Best PracticeOrdinal Model AlternativesCumulative Mod
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.
Random recurrence equations and ruin in a Markov-dependent stochastic economic environment
DEFF Research Database (Denmark)
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...
Institute of Scientific and Technical Information of China (English)
白鸿柏; 张培林; 黄协清
2001-01-01
研究了单自由度滑动摩擦系数随相对速度变化的干摩擦振动系统随机激励响应计算问题，提出了Krylov-Bogoliubov近似方法，并推导了相应的均方响应迭代方程。通过一个数值例分析，考察了简化为理想干摩擦模型时带来的均方响应计算误差。%By using Krylov-Bogoliubov approximate technique, the response computation of a single-degree-of-freedom dry friction damped system with velocity-dependent variable coefficient of sliding friction under random excitation was discussed, and the mean square response equation was also derived. At the same time, the error between Coulomb friction system with a system with velocity-dependent variable coefficient of sliding friction was obtained.
Separation of Variable Treatment for Solving Time-Dependent Potentials
Institute of Scientific and Technical Information of China (English)
QIAN Shang-Wu; GU Zhi-Yu; XIE Guo-Qiang
2001-01-01
We use the separation of variable treatment to treat some time-dependent systems, and point out that the condition of separability is the same as the condition of existence of invariant, and the separation of variable treatment is interrelated with the quantum-invariant method and the propagator method. We directly use the separation of potential.
Almost Sure Convergence of the General Jamison Weighted Sum of B-Valued Random Variables
Institute of Scientific and Technical Information of China (English)
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.
Yevdomakha, H. V.; Yu. M. Ivchenko; Skalozub, V. V.; Zhelieznov, K. H.; Litvinov, V. A.; O. P. Ivanov
2004-01-01
The authors propose models and calculation methods for optimal modes of running emu trains, taking into account the random character of catenary voltages and the conditions of dependence of electric power price upon the time of day. The paper suggests criteria for efficient use of variable tariffs and provides examples of calculating the optimal modes of running suburban emu trains.
Bias in random forest variable importance measures: Illustrations, sources and a solution
Hothorn Torsten; Zeileis Achim; Boulesteix Anne-Laure; Strobl Carolin
2007-01-01
Abstract Background Variable importance measures for random forests have been receiving increased attention as a means of variable selection in many classification tasks in bioinformatics and related scientific fields, for instance to select a subset of genetic markers relevant for the prediction of a certain disease. We show that random forest variable importance measures are a sensible means for variable selection in many applications, but are not reliable in situations where potential pred...
Stable limits for sums of dependent infinite variance random variables
DEFF Research Database (Denmark)
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...
Explaining the Dark Energy, Baryon and Dark Matter Coincidence via Domain-Dependent Random Densities
McDonald, John
2013-01-01
The dark energy, dark matter and baryon densities in the Universe are observed to be similar, with a factor of no more than 20 between the largest and smallest densities. We show that this coincidence can be understood via superhorizon domains of randomly varying densities when the baryon density at initial collapse of galaxy-forming perturbations is determined by anthropic selection. The baryon and dark matter densities are assumed to be dependent on random variables \\theta_{d} and \\theta_{b} according to \\rho_{dm} ~ \\theta_{d}^{\\alpha} and \\rho_{b} ~ \\theta_{b}^{\\beta}, while the effectively constant dark energy density is dependent upon a random variable \\phi_{Q} according to \\rho_{Q} ~ \\phi_{Q}^{n}. The ratio of the baryon density to the dark energy density at initial collapse, r_{Q}, and the baryon-to-dark matter ratio, r, are then determined purely statistically, with no dependence on the anthropically-preferred baryon density. We compute the probability distribution for r_{Q} and r and show that the ob...
LARGE DEVIATION FOR THE EMPIRICAL CORRELATION COEFFICIENT OF TWO GAUSSIAN RANDOM VARIABLES
Institute of Scientific and Technical Information of China (English)
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.
An almost Sure Central Limit Theorem for the Weight Function Sequences of NA Random Variables
Indian Academy of Sciences (India)
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.
Institute of Scientific and Technical Information of China (English)
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.
Directory of Open Access Journals (Sweden)
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.
Strong Approximation Theorems for Sums of Random Variables When Extreme Terms are Excluded
Institute of Scientific and Technical Information of China (English)
ZHANG Li Xin
2002-01-01
Let {Xn; n ≥1} be a sequence of i.i.d. random variables and let Xn(r) = Xj if |Xj| is the and necessary conditions for (r)Sn approximating to sums of independent normal random variables are obtained. Via approximation results, the convergence rates of the strong law of large numbers for (r)Sn are studied.
How fast increasing powers of a continuous random variable converge to Benford's law
Wójcik, Michał Ryszard
2013-01-01
It is known that increasing powers of a continuous random variable converge in distribution to Benford's law as the exponent approaches infinity. The rate of convergence has been estimated using Fourier analysis, but we present an elementary method, which is easier to apply and provides a better estimation in the widely studied case of a uniformly distributed random variable.
Complete Convergence for Arrays of Rowwise ϕ-mixing Random Variables
Institute of Scientific and Technical Information of China (English)
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.
Fuzzy random variables — II. Algorithms and examples for the discrete case
Kwakernaak, Huibert
1979-01-01
The results obtained in part I of the paper are specialized to the case of discrete fuzzy random variables. A more intuitive interpretation is given of the notion of fuzzy random variables. Algorithms are derived for determining expectations, fuzzy probabilities, fuzzy conditional expectations and f
Institute of Scientific and Technical Information of China (English)
Guo Ming-le; Xu Chun-yu; Zhu Dong-jin
2014-01-01
In this paper, we discuss the complete convergence of weighted sums for arrays of rowwise m-negatively associated random variables. By applying moment inequality and truncation methods, the sufficient conditions of complete convergence of weighted sums for arrays of rowwise m-negatively associated random variables are established. These results generalize and complement some known conclusions.
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...
'Sequence' dependent elasticity and local stiffness of a random heteropolymer
International Nuclear Information System (INIS)
We study the 'sequence' distribution of thermally averaged global and local elastic properties of a random heteropolymer of fixed length N, within the framework of a disordered Kratky–Porod (KP) model. We arrive at a number of qualitative results on the form of the distribution function of the thermally averaged end-to-end distance (R2), and its moments. For long N→∞ chains, this distribution is a Gaussian; for shorter chains, there is a crossover to an exponential distribution, with the most probable end-to-end distance deviating significantly from the mean. Further, the distributions of local quantities related to the thermally averaged tangent–tangent correlator are typically broad, even in the thermodynamic limit, i.e., they do not self-average. This is consistent with the general consensus that DNA–protein binding/unbinding strengths and rates are sensitive to local elastic distortion which is 'sequence' dependent
Stochastic Optimal Estimation with Fuzzy Random Variables and Fuzzy Kalman Filtering
Institute of Scientific and Technical Information of China (English)
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.
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. .
Bias in random forest variable importance measures: Illustrations, sources and a solution
Directory of Open Access Journals (Sweden)
Hothorn Torsten
2007-01-01
Full Text Available Abstract Background Variable importance measures for random forests have been receiving increased attention as a means of variable selection in many classification tasks in bioinformatics and related scientific fields, for instance to select a subset of genetic markers relevant for the prediction of a certain disease. We show that random forest variable importance measures are a sensible means for variable selection in many applications, but are not reliable in situations where potential predictor variables vary in their scale of measurement or their number of categories. This is particularly important in genomics and computational biology, where predictors often include variables of different types, for example when predictors include both sequence data and continuous variables such as folding energy, or when amino acid sequence data show different numbers of categories. Results Simulation studies are presented illustrating that, when random forest variable importance measures are used with data of varying types, the results are misleading because suboptimal predictor variables may be artificially preferred in variable selection. The two mechanisms underlying this deficiency are biased variable selection in the individual classification trees used to build the random forest on one hand, and effects induced by bootstrap sampling with replacement on the other hand. Conclusion We propose to employ an alternative implementation of random forests, that provides unbiased variable selection in the individual classification trees. When this method is applied using subsampling without replacement, the resulting variable importance measures can be used reliably for variable selection even in situations where the potential predictor variables vary in their scale of measurement or their number of categories. The usage of both random forest algorithms and their variable importance measures in the R system for statistical computing is illustrated and
Concentrated Hitting Times of Randomized Search Heuristics with Variable Drift
DEFF Research Database (Denmark)
Lehre, Per Kristian; Witt, Carsten
2014-01-01
Drift analysis is one of the state-of-the-art techniques for the runtime analysis of randomized search heuristics (RSHs) such as evolutionary algorithms (EAs), simulated annealing etc. The vast majority of existing drift theorems yield bounds on the expected value of the hitting time for a target...... precise sharp-concentration results on the running time of a simple EA on standard benchmark problems, including the class of general linear functions. The usefulness of the theorem outside the theory of RSHs is demonstrated by deriving tail bounds on the number of cycles in random permutations. All...
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. Generating schedule values for variable and random reinforcement schedules can be difficult. The present article describes the steps necessary to writ...
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.
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. PMID:25679737
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…
Directory of Open Access Journals (Sweden)
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
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
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.
The discovery of timescale-dependent color variability of quasars
Energy Technology Data Exchange (ETDEWEB)
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...
On the Strong Law of Large Numbers for Non-Independent B-Valued Random Variables
Institute of Scientific and Technical Information of China (English)
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
Institute of Scientific and Technical Information of China (English)
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
Directory of Open Access Journals (Sweden)
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.
A Robbins-Monro procedure for the estimation of parametric deformations on random variables
Fraysse, Philippe; Lescornel, Hélène; Loubès, Jean-Michel
2013-01-01
The paper is devoted to the study of a parametric deformation model of independent and identically random variables. Firstly, we construct an efficient and very easy to compute recursive estimate of the parameter. Our stochastic estimator is similar to the Robbins-Monro procedure where the contrast function is the Wasserstein distance. Secondly, we propose a recursive estimator similar to that of Parzen-Rosenblatt kernel density estimator in order to estimate the density of the random variabl...
Ultraviolet variability of quasars: dependence on the accretion rate
Meusinger, H.; Weiss, V.
2013-12-01
Aims: Although the variability in the ultraviolet and optical domain is one of the major characteristics of quasars, the dominant underlying mechanisms are still poorly understood. There is a broad consensus on the relationship between the strength of the variability and such quantities as time-lag, wavelength, luminosity, and redshift. However, evidence on a dependence on the fundamental parameters of the accretion process is still inconclusive. This paper is focused on the correlation between the ultraviolet quasar long-term variability and the accretion rate. Methods: We compiled a catalogue of about 4000 quasars including individual estimators for the variability strength derived from the multi-epoch photometry in the SDSS Stripe 82, virial black hole masses M derived from the Mg ii line, and mass accretion rates Ṁ from the Davis-Laor scaling relation. Several statistical tests were applied to evaluate the correlations of the variability with luminosity, mass, Eddington ratio, and accretion rate. Results: We confirm the existence of significant anti-correlations between the variability estimator V and the accretion rate Ṁ, the Eddington ratio ɛ, and the bolometric luminosity Lbol, respectively. The Eddington ratio is tightly correlated with Ṁ. A weak, statistically not significant positive trend is indicated for the dependence of V on M. As a side product, we find a strong correlation of the radiative efficiency η with M in our sample. We show via numerical simulations that this trend is most likely produced by selection effects in combination with the mass errors and the use of the scaling relation for Ṁ. The anti-correlations of V with Ṁ, ɛ, and Lbol cannot be explained in such a way. The strongest anti-correlation is found between V and Ṁ. However, it is difficult to decide which of the quantities L,ɛ, and Ṁ is intrinsically correlated with V and which of the observed correlations of V are produced by the L - ɛ - Ṁ relation. A V -
Shoulder pain and time dependent structure in wheelchair propulsion variability.
Jayaraman, Chandrasekaran; Moon, Yaejin; Sosnoff, Jacob J
2016-07-01
Manual wheelchair propulsion places considerable repetitive mechanical strain on the upper limbs leading to shoulder injury and pain. While recent research indicates that the amount of variability in wheelchair propulsion and shoulder pain may be related. There has been minimal inquiry into the fluctuation over time (i.e. time-dependent structure) in wheelchair propulsion variability. Consequently the purpose of this investigation was to examine if the time-dependent structure in the wheelchair propulsion parameters are related to shoulder pain. 27 experienced wheelchair users manually propelled their own wheelchair fitted with a SMARTWheel on a roller at 1.1m/s for 3min. Time-dependent structure of cycle-to-cycle fluctuations in contact angle and inter push time interval was quantified using sample entropy (SampEn) and compared between the groups with/without shoulder pain using non-parametric statistics. Overall findings were, (1) variability observed in contact angle fluctuations during manual wheelchair propulsion is structured (Z=3.15;pshoulder pain exhibited higher SampEn magnitude for contact angle during wheelchair propulsion than those without pain (χ(2)(1)=6.12;pshoulder pain (rs (WUSPI) =0.41;rs (VAS)=0.56;pshoulder pain. PMID:27134151
Stability of Random Variables and Iterated Logarithm Laws for Martingales and Quadratic Forms
Fernholz, Luisa Turrin; Teicher, Henry
1980-01-01
Strong laws of large numbers, obtained for positive, independent random variables, are utilized to prove iterated logarithm laws (with a nonrandom normalizing sequence) for a class of martingales. A law of the iterated logarithm is also established for certain random quadratic forms.
On the Strong Laws for Weighted Sums of m-negatively Asso ciated Random Variables
Institute of Scientific and Technical Information of China (English)
WU Yong-feng
2014-01-01
In this article, the author establishes the strong laws for linear statistics that are weighted sums of a m-negatively associated(m-NA) random sample. The obtained results extend and improve the result of Qiu and Yang in [1] to m-NA random variables.
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...
Institute of Scientific and Technical Information of China (English)
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.
The Sum and Difference of Two Lognormal Random Variables
Directory of Open Access Journals (Sweden)
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.
Dasgupta, Sakyasingha; Nishikawa, Isao; Aihara, Kazuyuki; Toyoizumi, Taro
Source of cortical variability and its influence on signal processing remain an open question. We address the latter, by studying two types of balanced randomly connected networks of quadratic I-F neurons, with irregular spontaneous activity: (a) a deterministic network with strong connections generating noise by chaotic dynamics (b) a stochastic network with weak connections receiving noisy input. They are analytically tractable in the limit of large network-size and channel time-constant. Despite different sources of noise, spontaneous activity of these networks are identical unless majority of neurons are simultaneously recorded. However, the two networks show remarkably different sensitivity to external stimuli. In the former, input reverberates internally and can be read out over long time, but in the latter, inputs rapidly decay. This is further enhanced with activity-dependent plasticity at input synapses producing marked difference in decoding inputs from neural activity. We show, this leads to distinct performance of the two networks to integrate temporally separate signals from multiple sources, with the deterministic chaotic network activity serving as reservoir for Monte Carlo sampling to perform near optimal Bayesian integration, unlike its stochastic counterpart.
The Central Limit Theorem for Exchangeable Random Variables Without Moments
Klass, Michael; Teicher, Henry
1987-01-01
If $\\{X_n, n \\geq 1\\}$ is an exchangeable sequence with $(1/b_n(\\sum^n_1X_i - a_n)) \\rightarrow N(0, 1)$ for some constants $a_n$ and $0 < b_n \\rightarrow \\infty$ then $b_n/n^\\alpha$ is slowly varying with $\\alpha = 1$ or $\\frac{1}{2}$ and necessary conditions (depending on $\\alpha$) which are also sufficient, are obtained. Three such examples are given, one with infinite mean, one with no positive moments, and the third with almost all conditional distributions belonging to no domain of attr...
LARGE DEVIATIONS FOR SUMS OF INDEPENDENT RANDOM VARIABLES WITH DOMINATEDLY VARYING TAILS
Institute of Scientific and Technical Information of China (English)
Kong Fanchao; Zhang Ying
2007-01-01
In this paper the large deviation results for partial and random sums Sn-ESn=n∑i=1Xi-n∑i=1EXi,n≥1;S(t)-ES(t)=N(t)∑i=1Xi-E(N(t)∑i=1Xi),t≥0are proved, where {N(t); t≥ 0} is a counting process of non-negative integer-valued random variables, and {Xn; n ≥ 1} are a sequence of independent non-negative random variables independent of {N(t); t ≥ 0}. These results extend and improve some known conclusions.
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.…
Variable Selection for Varying-Coefficient Models with Missing Response at Random
Institute of Scientific and Technical Information of China (English)
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.
Correction to: "On the Chambers-Mallows-Stuck Method for Simulating Skewed Stable Random Variables"
Weron, Rafal
1996-01-01
In the paper Weron (1996, Statist. Probab. Lett. 28, 165-171), I gave a proof to the equality in law of a skewed stable variable and a nonlinear transformation of two independent uniform and exponential variables. The Chambers et al. (1976, J. Amer. Statist. Assoc. 71, 340–344) method of computer generation of a skewed stable random variable is based on this equality. Unfortunately an error crept into my calculations for alpha=1. This note corrects the error.
Scalable statistics of correlated random variables and extremes applied to deep borehole porosities
Guadagnini, A.; Neuman, S. P.; Nan, T.; Riva, M.; Winter, C. L.
2015-02-01
We analyze scale-dependent statistics of correlated random hydrogeological variables and their extremes using neutron porosity data from six deep boreholes, in three diverse depositional environments, as example. We show that key statistics of porosity increments behave and scale in manners typical of many earth and environmental (as well as other) variables. These scaling behaviors include a tendency of increments to have symmetric, non-Gaussian frequency distributions characterized by heavy tails that decay with separation distance or lag; power-law scaling of sample structure functions (statistical moments of absolute increments) in midranges of lags; linear relationships between log structure functions of successive orders at all lags, known as extended self-similarity or ESS; and nonlinear scaling of structure function power-law exponents with function order, a phenomenon commonly attributed in the literature to multifractals. Elsewhere we proposed, explored and demonstrated a new method of geostatistical inference that captures all of these phenomena within a unified theoretical framework. The framework views data as samples from random fields constituting scale mixtures of truncated (monofractal) fractional Brownian motion (tfBm) or fractional Gaussian noise (tfGn). Important questions not addressed in previous studies concern the distribution and statistical scaling of extreme incremental values. Of special interest in hydrology (and many other areas) are statistics of absolute increments exceeding given thresholds, known as peaks over threshold or POTs. In this paper we explore the statistical scaling of data and, for the first time, corresponding POTs associated with samples from scale mixtures of tfBm or tfGn. We demonstrate that porosity data we analyze possess properties of such samples and thus follow the theory we proposed. The porosity data are of additional value in revealing a remarkable cross-over from one scaling regime to another at certain
Modelling the statistical dependence of rainfall event variables by a trivariate copula function
Directory of Open Access Journals (Sweden)
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.
CONVERGENCE RATES IN THE STRONG LAWS FOR A CLASS OF DEPENDENT RANDOM FIFLDS
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
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 semiparametric varying-coefficient partially linear models with missing response at random.The proposed procedure simultaneously selects significant variables in parametric components and nonparametric components.With appropriate selection of the tuning parameters,we establish the consistency of the variable selection procedure and the convergence rate of the regularized estimators.A simulation study is undertaken to assess the finite sample performance of the proposed variable selection procedure.
A Particle Swarm Optimization Algorithm with Variable Random Functions and Mutation
Institute of Scientific and Technical Information of China (English)
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.
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.
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...
Zwan, van der, G.; Vente, de, W.; Huizink, A.C.; Bögels, S.M.; Bruin, de, B.
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 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 a...
Convergence in distribution norms in the CLT for non identical distributed random variables
Bally, Vlad; Caramellino, Lucia; Poly, Guillaume
2016-01-01
We study the convergence in distribution norms in the Central Limit Theorem for non identical distributed random variables that is $$ \\varepsilon _{n}(f):=\\mathbb{E}\\Big(f\\Big(\\sum_{i=1}^{n}Z_{i}\\Big)\\Big)-\\mathbb{E}\\big(f(G)\\big)\\rightarrow 0 $$ where $S_{n}=\\sum_{i=1}^{n}Z_{i}$ with $Z_{i}$ centred independent random variables (with a suitable re-normalization for $S_{n}$) and $G$ is standard normal. We also consider local developments (Edgeworth expansion). This kind of results is well und...
ON THE LIMITING BEHAVIOR OF THE MAXIMUM PARTIAL SUMS FOR ARRAYS OF ROWWISE NA RANDOM VARIABLES
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Let {Xni, 1 ≤ n,i ＜∞} be an array of rowwise NA random variables and {an, n ≥ 1} a sequence of constants with 0 ＜ an ↑∞. The limiting behavior of maximum partial sums 1/an max 1≤k≤n| kΣi=1 Xni| is investigated and some new results are obtained. The results extend and improve the corresponding theorems of rowwise independent random variable arrays by Hu and Taylor [1] and Hu and Chang [2].
A note on strong law of large numbers of random variables
Institute of Scientific and Technical Information of China (English)
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
Institute of Scientific and Technical Information of China (English)
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
Institute of Scientific and Technical Information of China (English)
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.
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 $D=1,2,3,4$.
Randomly Weighted Sums for Negatively Associated Random Variables with Heavy Tails%重尾情形下NA随机变量的随机加权和
Institute of Scientific and Technical Information of China (English)
宗高峰; 孔繁超
2009-01-01
In 2003, Tang Qihe et al. obtained a simple asymptotic formula for independent identically distributed (i.i.d.) random variables with heavy tails. In this paper, under certain moment conditions, we establish a formula as the same as Tang's, when random variables are negatively associated (NA).
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.
Random Forests for Metric Learning with Implicit Pairwise Position Dependence
Xiong, Caiming; Xu, Ran; Corso, Jason J
2012-01-01
Metric learning makes it plausible to learn distances for complex distributions of data from labeled data. However, to date, most metric learning methods are based on a single Mahalanobis metric, which cannot handle heterogeneous data well. Those that learn multiple metrics throughout the space have demonstrated superior accuracy, but at the cost of computational efficiency. Here, we take a new angle to the metric learning problem and learn a single metric that is able to implicitly adapt its distance function throughout the feature space. This metric adaptation is accomplished by using a random forest-based classifier to underpin the distance function and incorporate both absolute pairwise position and standard relative position into the representation. We have implemented and tested our method against state of the art global and multi-metric methods on a variety of data sets. Overall, the proposed method outperforms both types of methods in terms of accuracy (consistently ranked first) and is an order of ma...
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.
A NONCLASSICAL LAW OF ITERATED LOGARITHM FOR NEGATIVELY ASSOCIATED RANDOM VARIABLES
Institute of Scientific and Technical Information of China (English)
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).
Institute of Scientific and Technical Information of China (English)
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.
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
Random forest (RF) is popular in ecological and environmental modeling, in part, because of its insensitivity to correlated predictors and resistance to overfitting. Although variable selection has been proposed to improve both performance and interpretation of RF models, it is u...
On Complete Convergence for Arrays of Rowwise Strong Mixing Random Variables
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
LIU WeiDong; FU KeAng; ZHANG LiXin
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.
Moments of the maximum of normed partial sums of ρ--mixing random variables
Institute of Scientific and Technical Information of China (English)
LIU Xiang-dong; LIU Jin-xia
2009-01-01
Let {Xn, n ≥ 1} be a sequence of identically distributed ρ--mixing random variables and set Sn= ∑ni=1>Xi,n ≥ 1, the sufficient and necessary conditions for the existence of moments of sup n≥1> |Sn/n1/r|p(00) are given, which are the same as that in the independent case.
Laws of Large Numbers of Negatively Correlated Random Variables for Capacities
Institute of Scientific and Technical Information of China (English)
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.
The Strong Law of Large Numbers for ~(ρ)-Mixing Random Variables
Institute of Scientific and Technical Information of China (English)
De Hua QIU
2012-01-01
In this paper we present some results for the general strong laws of large numbers of ~(ρ)-mixing random variables by a maximal inequality of Utev and Peligrad.These results extend and improve the related known works in the literature.
J.E. van der Zwan; W. de Vente; A.C. Huizink; S.M. Bögels; E.I. de Bruin
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
Sums and Products of Jointly Distributed Random Variables: A Simplified Approach
Stein, Sheldon H.
2005-01-01
Three basic theorems concerning expected values and variances of sums and products of random variables play an important role in mathematical statistics and its applications in education, business, the social sciences, and the natural sciences. A solid understanding of these theorems requires that students be familiar with the proofs of these…
Oracle Efficient Variable Selection in Random and Fixed Effects Panel Data Models
DEFF Research Database (Denmark)
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...
Multilevel Cell Storage and Resistance Variability in Resistive Random Access Memory
Pantelis, D. I.; Karakizis, P. N.; Dragatogiannis, D. A.; Charitidis, C. A.
2016-06-01
Multilevel per cell (MLC) storage in resistive random access memory (ReRAM) is attractive in achieving high-density and low-cost memory and will be required in future. In this chapter, MLC storage and resistance variability and reliability of multilevel in ReRAM are discussed. Different MLC operation schemes with their physical mechanisms and a comprehensive analysis of resistance variability have been provided. Various factors that can induce variability and their effect on the resistance margin between the multiple resistance levels are assessed. The reliability characteristics and the impact on MLC storage have also been assessed.
Cluster-size dependent randomization traffic flow model
Institute of Scientific and Technical Information of China (English)
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.
Structural Fatigue Reliability Based on Extension of Random Loads into Interval Variables
Directory of Open Access Journals (Sweden)
Qiangfeng Wang
2013-01-01
Full Text Available According to the problem that for a structure under random loads, the structural fatigue life cant be directly calculated out by S-N curves and linear Miner cumulative damage rule. Owing to the uncertainty of loads, and the problem of the inaccuracy of calculated structural reliability index for the existence of deviation between measured data in projects and real data, the research method for structural fatigue reliability based on extension of random loads into interval variables is proposed. The innovation is that we can accurately calculate out the interval of the structural fatigue life and reliability index of a structure according to the probability density function of stress level of random loads and the coefficient of variation of measured loads. By practical calculation example, it is proved that this method is more suitable to practical engineering comparing to traditional methods. It will provide a perfect research approach for reliability analysis of the structure under random loads.
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.
Hashimoto, H.; Nemani, R. R.
2015-12-01
Regional scale ecosystem modeling requires high-resolution data of surface climate variables. Spatial variability in temperature and precipitation has been well studied over the past two decades resulting in several sophisticated algorithms. However, compared to temperature and precipitation, other surface climate variables, such as humidity, solar radiation and wind speed, are not available to use, even though those data are equally important for ecosystem modeling. The main reason for this is the lack of governing physical equations for interpolating observations and the lack of comparable satellite observations. Therefore, scientists have been using reanalysis data or simply interpolated data for ecosystem modeling, though they are too coarse for regional scale ecosystem analysis. In this study, we developed a method to spatially map daily climate variables, including humidity, solar radiation, wind, precipitation, and temperature. We applied the method to the conterminous USA from 1980 to 2015. Previously, we successfully developed a precipitation interpolation method using random forest algorithm, and now we extended it to the other variables. Because this method does not require any assumptions about physical equations, this method can potentially be applicable to any climate variable if measured data are available. The method requires point data along with a host of spatial data sets . Satellite data, reanalysis data, and radar data were used and the importance of each dataset was analyzed using random forest algorithm. The only parameter we need to adjust is the radius from the target point, in which statistically meaningful relationships between observed and spatial co-variate data is calculated. The radius was optimized using mean absolute error and bias. We also analyzed temporal consistency and spatial patterns of the results. Because it is relatively easy to customize the setup depending on user's request, the resulting datasets may be useful for
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.
Hu, Zhen; Du, Xiaoping; Kolekar, Nitin S.; Banerjee, Arindam
2014-03-01
In robust design, uncertainty is commonly modelled with precise probability distributions. In reality, the distribution types and distribution parameters may not always be available owing to limited data. This research develops a robust design methodology to accommodate the mixture of both precise and imprecise random variables. By incorporating the Taguchi quality loss function and the minimax regret criterion, the methodology mitigates the effects of not only uncertain parameters but also uncertainties in the models of the uncertain parameters. Hydrokinetic turbine systems are a relatively new alternative energy technology, and both precise and imprecise random variables exist in the design of such systems. The developed methodology is applied to the robust design optimization of a hydrokinetic turbine system. The results demonstrate the effectiveness of the proposed methodology.
Institute of Scientific and Technical Information of China (English)
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.
The probability distribution function for the sum of squares of independent random variables
Fateev, Yury; Dmitriev, Dmitry; Tyapkin, Valery; Kremez, Nikolai; Shaidurov, Vladimir
2016-08-01
In the present paper, the probability distribution function is derived for the sum of squares of random variables for nonzero expectations. This distribution function enables one to develop an efficient one-step algorithm for phase ambiguity resolution when determining the spatial orientation from signals of satellite radio-navigation systems. Threshold values for rejecting false solutions and statistical properties of the algorithm are obtained.
Seok Yoon Hwang; Dug Hun Hong
1999-01-01
LetÃ‚Â {Xij} be a double sequence of pairwise independent random variables.Ã‚Â IfÃ‚Â P{|Xmn|Ã¢Â‰Â¥t}Ã¢Â‰Â¤P{|X|Ã¢Â‰Â¥t} for all nonnegative real numbersÃ‚Â t and E|X|p(log+|X|)3
General Limit Distributions for Sums of Random Variables with a Matrix Product Representation
Angeletti, Florian; Bertin, Eric; Abry, Patrice
2014-12-01
The general limit distributions of the sum of random variables described by a finite matrix product ansatz are characterized. Using a mapping to a Hidden Markov Chain formalism, non-standard limit distributions are obtained, and related to a form of ergodicity breaking in the underlying non-homogeneous Hidden Markov Chain. The link between ergodicity and limit distributions is detailed and used to provide a full algorithmic characterization of the general limit distributions.
Central limit theorems for directional and linear random variables with applications
García-Portugués, Eduardo; Crujeiras, Rosa M.; González-Manteiga, Wenceslao
2014-01-01
A central limit theorem for the integrated squared error of the directional-linear kernel density estimator is established. The result enables the construction and analysis of two testing procedures based on squared loss: a nonparametric independence test for directional and linear random variables and a goodness-of-fit test for parametric families of directional-linear densities. Limit distributions for both test statistics, and a consistent bootstrap strategy for the goodness-of-fit test, a...
On Stein's method for products of normal random variables and zero bias couplings
Gaunt, Robert E.
2013-01-01
In this paper we extend Stein's method to the distribution of the product of $n$ independent mean zero normal random variables. A Stein equation is obtained for this class of distributions, which reduces to the classical normal Stein equation in the case $n=1$. This Stein equation motivates a generalisation of the zero bias transformation. We establish properties of this new transformation, and illustrate how they may be used together with the Stein equation to assess distributional distances...
The effect of cluster size variability on statistical power in cluster-randomized trials.
Directory of Open Access Journals (Sweden)
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.
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
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.
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.
Directory of Open Access Journals (Sweden)
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.
Institute of Scientific and Technical Information of China (English)
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.
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
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
Criticality in Two-Variable Earthquake Model on a Random Graph
Institute of Scientific and Technical Information of China (English)
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.
Records and sequences of records from random variables with a linear trend
Franke, Jasper; Wergen, Gregor; Krug, Joachim
2010-01-01
We consider records and sequences of records drawn from discrete time series of the form $X_{n}=Y_{n}+cn$, where the $Y_{n}$ are independent and identically distributed random variables and $c$ is a constant drift. For very small and very large drift velocities, we investigate the asymptotic behavior of the probability $p_n(c)$ of a record occurring in the $n$th step and the probability $P_N(c)$ that all $N$ entries are records, i.e. that $X_1 < X_2 < ... < X_N$. Our work is motivated by the ...
Latitudinal dependence of the variability of the micrometeor altitude distribution
Sparks, J. J.; Janches, D.
2009-06-01
We present a study of the diurnal behavior of the observed meteor altitude distribution at different seasons and latitudes. The meteor altitude distribution provides an indication of where the meteoric mass deposition occurs in the mesosphere and lower thermosphere (MLT). This can be utilized to model the input of metallic constituents into the MLT and accurately understand the chemistry of this region. We show that the observed altitude distributions have distinct variability at each location: at high latitudes there is a weak diurnal and strong seasonal variability while at tropical latitudes the opposite behavior is observed. We explain these results by correlating them with the astronomical and physical properties of the meteoric flux. Finally, we discussed the potential influences that these results have on the metal chemistry and aeronomy of this atmospheric region.
The Energy Dependence of GRB Minimum Variability Timescales
Golkhou, V. Zach; Butler, Nathaniel R.; Littlejohns, Owen M.
2015-10-01
We constrain the minimum variability timescales for 938 gamma-ray bursts (GRBs) observed by the Fermi/Gamma-ray Burst Monitor instrument prior to 2012 July 11. The tightest constraints on progenitor radii derived from these timescales are obtained from light curves in the hardest energy channel. In the softer bands—or from measurements of the same GRBs in the hard X-rays from Swift—we show that variability timescales tend to be a factor of two to three longer. Applying a survival analysis to account for detections and upper limits, we find median minimum timescale in the rest frame for long-duration and short-duration GRBs of 45 and 10 ms, respectively. Less than 10% of GRBs show evidence for variability on timescales below 2 ms. These shortest timescales require Lorentz factors ≳ 400 and imply typical emission radii R≈ 1× {10}14 cm for long-duration GRBs and R≈ 3× {10}13 cm for short-duration GRBs. We discuss implications for the GRB fireball model and investigate whether or not GRB minimum timescales evolve with cosmic time.
The Energy-Dependence of GRB Minimum Variability Timescales
Golkhou, V Zach; Littlejohns, Owen M
2015-01-01
We constrain the minimum variability timescales for 938 GRBs observed by the Fermi/GBM instrument prior to July 11, 2012. The tightest constraints on progenitor radii derived from these timescales are obtained from light curves in the hardest energy channel. In the softer bands -- or from measurements of the same GRBs in the hard X-rays from Swift -- we show that variability timescales tend to be a factor 2--3 longer. Applying a survival analysis to account for detections and upper limits, we find median minimum timescale in the rest frame for long-duration and short-duration GRBs of 45 ms and 10 ms, respectively. Fewer than 10% of GRBs show evidence for variability on timescales below 2 ms. These shortest timescales require Lorentz factors $\\gtrsim 400$ and imply typical emission radii $R \\approx 1 {\\times} 10^{14}$ cm for long-duration GRBs and $R \\approx 3 {\\times} 10^{13}$ cm for short-duration GRBs. We discuss implications for the GRB fireball model and investigate whether GRB minimum timescales evolve w...
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 ...
Institute of Scientific and Technical Information of China (English)
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.
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. PMID:26111942
A THEOREM ON THE CONVERGENCE OF SUMS OF INDEPENDENT RANDOM VARIABLES
Institute of Scientific and Technical Information of China (English)
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.
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.
Return Probability of the Open Quantum Random Walk with Time-Dependence
Institute of Scientific and Technical Information of China (English)
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?"
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
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.
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).
Bias phase and light power dependence of the random walk coefficient of fiber optic gyroscope
Institute of Scientific and Technical Information of China (English)
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.
Energy decay of a variable-coefficient wave equation with nonlinear time-dependent localized damping
Directory of Open Access Journals (Sweden)
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.
Lloret Cabot, M.; Hicks, M. A.; van den Eijnden, A. P.
2012-01-01
Spatial variability of soil properties is inherent in soil deposits, whether as a result of natural geological processes or engineering construction. It is therefore important to account for soil variability in geotechnical design in order to represent more realistically a soil’s in situ state. This variability may be modelled as a random field, with a given probability density function and scale of fluctuation. A more convenient way to deal with the uncertainty of a soil property due to spat...
Polymers on disordered hierarchical lattices: A nonlinear combination of random variables
Energy Technology Data Exchange (ETDEWEB)
Cook, J. (Commissariat a l' Energie Atomique, Gif-sur-Yvette (France) Univ. of Edinburgh (England)); Derrida, B. (Commissariat a l' Energie Atomique, Gif-sur-Yvette (France))
1989-10-01
The problem of directed polymers on disordered hierarchical and hypercubic lattices is considered. For the hierarchical lattices the problem can be reduced to the study of the stable laws for combining random variables in a nonlinear way. The authors present the results of numerical simulations of two hierarchical lattices, finding evidence of a phase transition in one case. For a limiting case they extend the perturbation theory developed by Derrida and Griffiths to nonzero temperature and to higher order and use this approach to calculate thermal and geometrical properties (overlaps) of the model. In this limit they obtain an interpolation formula, allowing one to obtain the noninteger moments of the partition function from the integer moments. They obtain bounds for the transition temperature for hierarchical and hypercubic lattices, and some similarities between the problem on the two different types of lattice are discussed.
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.
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.
Directory of Open Access Journals (Sweden)
Tyson H Holmes
2011-07-01
Full Text Available The HIV risk-taking behavior scale (HRBS is an 11-item instrument designed to assess the risks of HIV infection due self-reported injection drug use and sexual behavior. A retrospective analysis was performed on HRBS data collected from approximately 1,000 participants pooled across seven clinical trials of pharmacotherapies for either the treatment of cocaine-dependence or methamphetamine-dependence. Analysis faced three important challenges. The sample contained a high proportion of missing assessments after randomization. Also, the HRBS scale consists of two distinct behavioral components which may or may not coincide in response patterns. In addition, distributions of responses on the subscales were highly concentrated at just a few values (e.g., 0, 6. To address these challenges, a single probit regression model was fit to three outcomes variables simultaneously—the two subscale totals plus an indicator variable for assessments not obtained (non-response. This joint-outcome regression model was able to identify that those who left assessment early had higher self-reported risk of injection-drug use and lower self-reported risky sexual behavior because the model was able to draw on information on associations among the three outcomes collectively. These findings were not identified in analyses performed on each outcome separately. No evidence for an effect of pharmacotherapies was observed, except to reduce missing assessments. Univariate-outcome modeling is not recommended for the HRBS.
Institute of Scientific and Technical Information of China (English)
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.
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 ...
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.
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.
Institute of Scientific and Technical Information of China (English)
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.
Kaspar, H.; Newsbaum, J. B.
1967-01-01
Relationships between independent and dependent variables are determined by multiple correlation computer program. This is applied to research and experimental design and development of complex hardware and components that require test programs.
Dhingra, R. R.; Jacono, F. J.; Fishman, M; Loparo, K. A.; Rybak, I. A.; Dick, T E
2011-01-01
Physiological rhythms, including respiration, exhibit endogenous variability associated with health, and deviations from this are associated with disease. Specific changes in the linear and nonlinear sources of breathing variability have not been investigated. In this study, we used information theory-based techniques, combined with surrogate data testing, to quantify and characterize the vagal-dependent nonlinear pattern variability in urethane-anesthetized, spontaneously breathing adult rat...
Chastaing, Gaëlle; Prieur, Clémentine
2011-01-01
In this paper, we consider a regression model built on dependent variables. This regression modelizes an input output relationship. Under boundedness assumptions on the joint distribution function of the input variables, we show that a generalized Hoeffding-Sobol decomposition is available. This leads to new indices measuring the sensitivity of the output with respect to the input variables. We also study and discuss the estimation of these new indices.
DEFF Research Database (Denmark)
Mikosch, Thomas Valentin; Moser, Martin
2013-01-01
We investigate the maximum increment of a random walk with heavy-tailed jump size distribution. Here heavy-tailedness is understood as regular variation of the finite-dimensional distributions. The jump sizes constitute a strictly stationary sequence. Using a continuous mapping argument acting...... on the point processes of the normalized jump sizes, we prove that the maximum increment of the random walk converges in distribution to a Fréchet distributed random variable....
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.
Directory of Open Access Journals (Sweden)
Anita Sharma
2011-01-01
Full Text Available Blinking statistics of quantum dot has attracted much attraction in recent years. Various experiments were conducted and various theories have been given to explain this phenomenon. However, the problem is not yet resolved. The weak temperature dependence of the power law parameters have complicated the phenomena. We have simulated the blinking statistics of quantum dot based on the random walk model. We have shown that three-dimensional biased Levy random walk of electrons, the bias being the Columbic interaction between electrons and ionized atoms can explain the observed experimental results. We have simulated the blinking properties of quantum dots in a broad temperature range (10-300 K. The distributions exhibit power law behavior for a wide range of temperature, but the power law parameter increases marginally with temperature. The trend of change is independent of the size of the quantum dots as confirmed from the simulation.
Directory of Open Access Journals (Sweden)
Coletta Filho Helvécio Della
2000-01-01
Full Text Available RAPD analysis of 19 Ponkan mandarin accessions was performed using 25 random primers. Of 112 amplification products selected, only 32 were polymorphic across five accessions. The absence of genetic variability among the other 14 accessions suggested that they were either clonal propagations with different local names, or that they had undetectable genetic variability, such as point mutations which cannot be detected by RAPD.
Bell-Boole Inequality: Nonlocality or Probabilistic Incompatibility of Random Variables?
Directory of Open Access Journals (Sweden)
Andrei Khrennikov
2008-03-01
Full Text Available The main aim of this report is to inform the quantum information community about investigations on the problem of probabilistic compatibility of a family of random variables: a possibility to realize such a family on the basis of a single probability measure (to construct a single Kolmogorov probability space. These investigations were started hundred of years ago by J. Boole (who invented Boolean algebras. The complete solution of the problem was obtained by Soviet mathematician Vorobjev in 60th. Surprisingly probabilists and statisticians obtained inequalities for probabilities and correlations among which one can find the famous BellÃ¢Â€Â™s inequality and its generalizations. Such inequalities appeared simply as constraints for probabilistic compatibility. In this framework one can not see a priori any link to such problems as nonlocality and Ã¢Â€Âœdeath of realityÃ¢Â€Â which are typically linked to BellÃ¢Â€Â™s type inequalities in physical literature. We analyze the difference between positions of mathematicians and quantum physicists. In particular, we found that one of the most reasonable explanations of probabilistic incompatibility is mixing in BellÃ¢Â€Â™s type inequalities statistical data from a number of experiments performed under different experimental contexts.
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.
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.
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
Large Deviations for Sums of Heavy-tailed Random Variables%重尾随机变量和的大偏差
Institute of Scientific and Technical Information of China (English)
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.
Nutrition education intervention for dependent patients: protocol of a randomized controlled trial
Directory of Open Access Journals (Sweden)
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
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.
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.
Directory of Open Access Journals (Sweden)
Janssen Patricia A
2012-12-01
Full Text Available Abstract Background The prevalence of maternal drug use during pregnancy in North America has been estimated to be as high as 6-10%. The consequences for the newborn include increased risk for perinatal mortality and ongoing physical, neurobehavioral, and psychosocial problems. Methadone is frequently used to wean women off street drugs but is implicated as a cause of adverse fetal/neonatal outcomes itself. The purpose of our study was to test the ability of maternal acupuncture treatment among mothers who use illicit drugs to reduce the frequency and severity of withdrawal symptoms among their newborns. Methods We randomly assigned chemically dependent pregnant women at BC Women’s Hospital in Vancouver, British Columbia to daily acupuncture treatments versus usual care. By necessity, neither our participants nor acupuncturists were blinded as to treatment allocation. Our primary outcome was days of neonatal morphine treatment for symptoms of neonatal withdrawal. Secondary neonatal outcomes included admission to a neonatal ICU and transfer to foster care. Results We randomized 50 women to acupuncture and 39 to standard care. When analyzed by randomized groups, we did not find benefit of acupuncture; the average length of treatment with morphine for newborns in the acupuncture group was 2.7 (6.3 compared to 2.8 (7.0 in the control group. Among newborns of women who were compliant with the acupuncture regime, we observed a reduction of 2.1 and 1.5 days in length of treatment for neonatal abstinence syndrome compared to the non-compliant and control groups, respectively. These differences were not statistically significant. Conclusions Acupuncture may be a safe and feasible treatment to assist mothers to reduce their dosage of methadone. Our results should encourage ongoing studies to test the ability of acupuncture to mitigate the severity of neonatal abstinence syndrome among their newborns. Clinical Trial Registration http
Time-dependent Relativistic Mean-field Theory and Random Phase Approximation
Institute of Scientific and Technical Information of China (English)
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
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
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,
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)
Omnibus Tests for Interactions in Repeated Measures Designs with Dichotomous Dependent Variables.
Serlin, Ronald C.; Marascuilo, Leonard A.
When examining a repeated measures design with independent groups for a significant group by trial interaction, classical analysis of variance or multivariate procedures can be used if the assumptions underlying the tests are met. Neither procedure may be justified for designs with small sample sizes and dichotomous dependent variables. An omnibus…
Kim, Junhan; Chan, Chi-kwan; Medeiros, Lia; Ozel, Feryal; Psaltis, Dimitrios
2016-01-01
The Event Horizon Telescope (EHT) is a millimeter-wavelength, very-long baseline interferometer (VLBI) 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. We also apply our method to the early EHT data...
Theodorou, C. G.; Ioannidis, E. G.; Haendler, S.; Josse, E.; Dimitriadis, C. A.; Ghibaudo, G.
2016-03-01
In this paper, a parametric statistical analysis of the low-frequency noise (LFN) in very small area (W·L ≈ 10-3 μm2) 14 nm fully depleted silicon-on-insulator (FD-SOI) n-MOS devices is presented. It has been demonstrated that the LFN origin is due to carrier trapping/detrapping into gate dielectric traps near the interface and the mean noise level in such small area MOSFETs is well approached by the carrier number fluctuations model in all measurement conditions. The impact of gate voltage bias and temperature on the LFN variability, as well as the standard deviation dependence on frequency have been studied for the first time, focusing on their relation to the Random Telegraph Noise (RTN) effect and its characteristics.
Directory of Open Access Journals (Sweden)
Senol Emir
2016-04-01
Full Text Available The purpose of this study is to explore the importance and ranking of technical analysis variables in Turkish banking sector. Random Forest method is used for determining importance scores of inputs for eight banks in Borsa Istanbul. Then two predictive models utilizing Random Forest (RF and Artificial Neural Networks (ANN are built for predicting BIST-100 index and bank closing prices. Results of the models are compared by three metrics namely Mean Absolute Error (MAE, Mean Square Error (MSE, Median Absolute Error (MedAE. Findings show that moving average (MAV-100 is the most important variable for both BIST -100 index and bank closing prices. Therefore, investors should follow this technical indicator with respect to Turkish banks. In addition ANN shows better performance for all metrics.
Major, Péter
1999-01-01
Let $\\xi_1,\\xi_2\\ldots$ be a sequence of i.i.d.random variables, and consider the elementary symmetric polynomial $S ^(k)(n)$ of order $k =k(n)$ of the first $n$ elements $\\xi_1\\ldots,\\xi_n$ of this sequence. We are interested in the limit behavior of $S^(k) (n)$ with an appropriate transformation if $k(n)/n\\rightarrow\\alpha, 0
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.
Ahmadi-Abhari Seyed Ali; Radgoodarzi Reza; Assadi Seyed Mohammad
2003-01-01
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. S...
Directory of Open Access Journals (Sweden)
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
Continuous infusion of propofol at variable rates in a time dependent in cats
Felipe Comassetto; Martielo Ivan Gehrcke; Marcos Paulo Antunes de Lima; Ronise Tocheto; Nilson Oleskovicz
2015-01-01
Felines biotransforms propofol slowly developing cumulative effect. The aim this study was to develop a scheme of continuous infusion of propofol at time dependent variable rate in cats. Sixteen healthy female cats undergoing elective ovariohysterectomy and received as premedication dexmedetomidine (2.5 ?g/kg), methadone (0.5 mg/kg) and ketamine (0.5 mg/kg) administrated at intramuscular rote. After 15 minutes , the animals were allocated into two groups : Fixed Rate (GFR), which received pro...
Galea, J. M.; Ruge, D.; Buijink, A.; Bestmann, S.; Rothwell, J. C.
2013-01-01
Action selection describes the high-level process which selects between competing movements. In animals, behavioural variability is critical for the motor exploration required to select the action which optimizes reward and minimizes cost/punishment, and is guided by dopamine (DA). The aim of this study was to test in humans whether low-level movement parameters are affected by punishment and reward in ways similar to high-level action selection. Moreover, we addressed the proposed dependence...
LENUS (Irish Health Repository)
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.
Institute of Scientific and Technical Information of China (English)
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.
Zied, Hajej; Dellagi, Sofiene; Rezg, Nidhal
2011-01-01
Abstract This paper deals with combined production and maintenance plans for a manufacturing system satisfying a random demand. We first establish an optimal production plan which minimizes the average total inventory and production cost. Secondly, using this optimal production plan, and taking into account the deterioration of the machine according to its production rate, we derive an optimal maintenance schedule which minimizes the maintenance cost. A numerical example illustrate...
Plass-Johnson, Jeremiah G; Taylor, Marc H; Husain, Aidah A A; Teichberg, Mirta C; Ferse, Sebastian C A
2016-01-01
Changes in the coral reef complex can affect predator-prey relationships, resource availability and niche utilisation in the associated fish community, which may be reflected in decreased stability of the functional traits present in a community. This is because particular traits may be favoured by a changing environment, or by habitat degradation. Furthermore, other traits can be selected against because degradation can relax the association between fishes and benthic habitat. We characterised six important ecological traits for fish species occurring at seven sites across a disturbed coral reef archipelago in Indonesia, where reefs have been exposed to eutrophication and destructive fishing practices for decades. Functional diversity was assessed using two complementary indices (FRic and RaoQ) and correlated to important environmental factors (live coral cover and rugosity, representing local reef health, and distance from shore, representing a cross-shelf environmental gradient). Indices were examined for both a change in their mean, as well as temporal (short-term; hours) and spatial (cross-shelf) variability, to assess whether fish-habitat association became relaxed along with habitat degradation. Furthermore, variability in individual traits was examined to identify the traits that are most affected by habitat change. Increases in the general reef health indicators, live coral cover and rugosity (correlated with distance from the mainland), were associated with decreases in the variability of functional diversity and with community-level changes in the abundance of several traits (notably home range size, maximum length, microalgae, detritus and small invertebrate feeding and reproductive turnover). A decrease in coral cover increased variability of RaoQ while rugosity and distance both inversely affected variability of FRic; however, averages for these indices did not reveal patterns associated with the environment. These results suggest that increased
International Nuclear Information System (INIS)
Several problems related to the application of the theory of random by means of state variables are studied. The well-known equations that define the propagation of the mean and the variance for linear and non-linear systems are first presented. The Monte Carlo method is next resorted to in order to determine the applicability of the hypothesis of a normally distributed output in case of linear systems subjected to non-Gaussian excitations. Finally, attention is focused on the properties of linear filters and modulation functions proposed to simulate seismic excitations as non stationary random processes. Acceleration spectra obtained by multiplying rms spectra by a constant factor are compared with design spectra suggested by several authors for various soil conditions. In every case, filter properties are given. (Author)
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
Motor variability arises from a slow random walk in neural state.
Chaisanguanthum, Kris S; Shen, Helen H; Sabes, Philip N
2014-09-01
Even well practiced movements cannot be repeated without variability. This variability is thought to reflect "noise" in movement preparation or execution. However, we show that, for both professional baseball pitchers and macaque monkeys making reaching movements, motor variability can be decomposed into two statistical components, a slowly drifting mean and fast trial-by-trial fluctuations about the mean. The preparatory activity of dorsal premotor cortex/primary motor cortex neurons in monkey exhibits similar statistics. Although the neural and behavioral drifts appear to be correlated, neural activity does not account for trial-by-trial fluctuations in movement, which must arise elsewhere, likely downstream. The statistics of this drift are well modeled by a double-exponential autocorrelation function, with time constants similar across the neural and behavioral drifts in two monkeys, as well as the drifts observed in baseball pitching. These time constants can be explained by an error-corrective learning processes and agree with learning rates measured directly in previous experiments. Together, these results suggest that the central contributions to movement variability are not simply trial-by-trial fluctuations but are rather the result of longer-timescale processes that may arise from motor learning. PMID:25186752
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.
Institute of Scientific and Technical Information of China (English)
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.
Variability of visual responses of superior colliculus neurons depends on stimulus velocity.
Mochol, Gabriela; Wójcik, Daniel K; Wypych, Marek; Wróbel, Andrzej; Waleszczyk, Wioletta J
2010-03-01
Visually responding neurons in the superficial, retinorecipient layers of the cat superior colliculus receive input from two primarily parallel information processing channels, Y and W, which is reflected in their velocity response profiles. We quantified the time-dependent variability of responses of these neurons to stimuli moving with different velocities by Fano factor (FF) calculated in discrete time windows. The FF for cells responding to low-velocity stimuli, thus receiving W inputs, increased with the increase in the firing rate. In contrast, the dynamics of activity of the cells responding to fast moving stimuli, processed by Y pathway, correlated negatively with FF whether the response was excitatory or suppressive. These observations were tested against several types of surrogate data. Whereas Poisson description failed to reproduce the variability of all collicular responses, the inclusion of secondary structure to the generating point process recovered most of the observed features of responses to fast moving stimuli. Neither model could reproduce the variability of low-velocity responses, which suggests that, in this case, more complex time dependencies need to be taken into account. Our results indicate that Y and W channels may differ in reliability of responses to visual stimulation. Apart from previously reported morphological and physiological differences of the cells belonging to Y and W channels, this is a new feature distinguishing these two pathways. PMID:20203179
Degree of multicollinearity and variables involved in linear dependence in additive-dominant models
Directory of Open Access Journals (Sweden)
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.
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…
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. PMID:24893001
The dependence of J/ψ-nucleon inelastic cross section on the Feynman variable
Institute of Scientific and Technical Information of China (English)
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.
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
DEFF Research Database (Denmark)
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...
对随机变量独立性的几点认识%Some Recognition on Independence of Random Variables
Institute of Scientific and Technical Information of China (English)
闻斌
2012-01-01
独立性是概率统计的一个重要概念，给出了随机变量独立性的一些特殊性质．%Independence is an important concept in probability and statistics. In this paper, we present a number of propositions on independence of random variables; furthermore some properties of the independence of random variables are given.
Memory effects, two color percolation, and the temperature dependence of Mott variable-range hopping
Agam, Oded; Aleiner, Igor L.
2014-06-01
There are three basic processes that determine hopping transport: (a) hopping between normally empty sites (i.e., having exponentially small occupation numbers at equilibrium), (b) hopping between normally occupied sites, and (c) transitions between normally occupied and unoccupied sites. In conventional theories all these processes are considered Markovian and the correlations of occupation numbers of different sites are believed to be small (i.e., not exponential in temperature). We show that, contrary to this belief, memory effects suppress the processes of type (c) and manifest themselves in a subleading exponential temperature dependence of the variable-range hopping conductivity. This temperature dependence originates from the property that sites of type (a) and (b) form two independent resistor networks that are weakly coupled to each other by processes of type (c). This leads to a two-color percolation problem which we solve in the critical region.
Vu, Van Hoan; Isableu, Brice; Berret, Bastien
2016-07-22
The purpose of this study was to investigate the nature of the variables and rules underlying the planning of unrestrained 3D arm reaching. To identify whether the brain uses kinematic, dynamic and energetic values in an isolated manner or combines them in a flexible way, we examined the effects of speed variations upon the chosen arm trajectories during free arm movements. Within the optimal control framework, we uncovered which (possibly composite) optimality criterion underlays at best the empirical data. Fifteen participants were asked to perform free-endpoint reaching movements from a specific arm configuration at slow, normal and fast speeds. Experimental results revealed that prominent features of observed motor behaviors were significantly speed-dependent, such as the chosen reach endpoint and the final arm posture. Nevertheless, participants exhibited different arm trajectories and various degrees of speed dependence of their reaching behavior. These inter-individual differences were addressed using a numerical inverse optimal control methodology. Simulation results revealed that a weighted combination of kinematic, energetic and dynamic cost functions was required to account for all the critical features of the participants' behavior. Furthermore, no evidence for the existence of a speed-dependent tuning of these weights was found, thereby suggesting subject-specific but speed-invariant weightings of kinematic, energetic and dynamic variables during the motor planning process of free arm movements. This suggested that the inter-individual difference of arm trajectories and speed dependence was not only due to anthropometric singularities but also to critical differences in the composition of the subjective cost function. PMID:27132233
Lloyd, Mark C; Cunningham, Jessica J; Bui, Marilyn M; Gillies, Robert J; Brown, Joel S; Gatenby, Robert A
2016-06-01
Spatial heterogeneity in tumors is generally thought to result from branching clonal evolution driven by random mutations that accumulate during tumor development. However, this concept rests on the implicit assumption that cancer cells never evolve to a fitness maximum because they can always acquire mutations that increase proliferative capacity. In this study, we investigated the validity of this assumption. Using evolutionary game theory, we demonstrate that local cancer cell populations will rapidly converge to the fittest phenotype given a stable environment. In such settings, cellular spatial heterogeneity in a tumor will be largely governed by regional variations in environmental conditions, for example, alterations in blood flow. Model simulations specifically predict a common spatial pattern in which cancer cells at the tumor-host interface exhibit invasion-promoting, rapidly proliferating phenotypic properties, whereas cells in the tumor core maximize their population density by promoting supportive tissue infrastructures, for example, to promote angiogenesis. We tested model predictions through detailed quantitative image analysis of phenotypic spatial distribution in histologic sections of 10 patients with stage 2 invasive breast cancers. CAIX, GLUT1, and Ki67 were upregulated in the tumor edge, consistent with an acid-producing invasive, proliferative phenotype. Cells in the tumor core were 20% denser than the edge, exhibiting upregulation of CAXII, HIF-1Î±, and cleaved caspase-3, consistent with a more static and less proliferative phenotype. Similarly, vascularity was consistently lower in the tumor center compared with the tumor edges. Lymphocytic immune responses to tumor antigens also trended to higher level in the tumor edge, although this effect did not reach statistical significance. Like invasive species in nature, cancer cells at the leading edge of the tumor possess a different phenotype from cells in the tumor core. Our results suggest
Saddlepoint approximation based structural reliability analysis with non-normal random variables
Institute of Scientific and Technical Information of China (English)
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
Spectral variability of deciduous leaves depending on the developmental stages and tree condition
Song, Y.; Ryu, Y.
2013-12-01
Foliar spectral characteristics could be the key information in modeling forest ecosystem and the remote sensing of vegetation identification. But it is not easy to determine a typical leaf spectrum of a species in a standardized state. That is because of variables critically influencing on the spectral property of leaves, such as inter- and intra-species features, phenological phase, or biotic and abiotic stress. In this study, we attempted to quantify the spectral variability of leaves depending on species, developmental stages, and the condition of trees. The contribution of these factors to the spectral variation was analyzed at the single leaf level, with a large number of samples from deciduous plants in the urban forested area. First, we collected tens of leaf-samples at every biweekly fieldwork in the growing season, for the selected 5 tree species popular in urban parks; Acer palmatum, Carpinus laxiflora, Prunus yedoensis, Quercus acutissima, and Zelkova serrata. And absorbance, reflectance and transmittance spectra of the leaves were acquired at the short-visible (400-700 nm) to infrared (700-2500 nm) spectral region with 1 nm interval. Seasonality in these leaf-spectra was used to understand the inter-species variation depending on developmental stages. Second, as a benchmark for testing intra-species variability and differences by tree condition, we additionally analyzed the spectral reflectance of 504 ripe leaves from 56 cherry trees (Cerasus × yedoensis) collected in the middle of summer. Last, using ANOVA (analysis of variance) and general linear model, we assessed the influence of our tested variables (i.e., species, developmental stage, and tree condition) on the spectral characteristics and their vegetation indices. As a result, we clarified that the changes in leaf-spectra was apparent across all the tested species during the growing season from May to June, indicating the increasing trend of absorbance in photosynthetically active radiation
Burmeister Getz, E; Carroll, K J; Jones, B; Benet, L Z
2016-09-01
Current pharmacokinetic (PK) bioequivalence guidelines do not account for batch-to-batch variability in study design or analysis. Here we evaluate the magnitude of batch-to-batch PK variability for Advair Diskus 100/50. Single doses of fluticasone propionate and salmeterol combinations were administered by oral inhalation to healthy subjects in a randomized clinical crossover study comparing three different batches purchased from the market, with one batch replicated across two treatment periods. All pairwise comparisons between different batches failed the PK bioequivalence statistical test, demonstrating substantial PK differences between batches that were large enough to demonstrate bio-inequivalence in some cases. In contrast, between-replicate PK bioequivalence was demonstrated for the replicated batch. Between-batch variance was ∼40-70% of the estimated residual error. This large additional source of variability necessitates re-evaluation of bioequivalence assessment criteria to yield a result that is both generalizable and consistent with the principles of type I and type II error rate control. PMID:27037630
Recovery of microstructure properties: random variability of soil solid thermal conductivity
Directory of Open Access Journals (Sweden)
Stefaniuk Damian
2016-03-01
Full Text Available In this work, the complex microstructure of the soil solid, at the microscale, is modeled by prescribing the spatial variability of thermal conductivity coefficient to distinct soil separates. We postulate that the variation of thermal conductivity coefficient of each soil separate can be characterized by some probability density functions: fCl(λ, fSi(λ, fSa(λ, for clay, silt and sand separates, respectively. The main goal of the work is to recover/identify these functions with the use of back analysis based on both computational micromechanics and simulated annealing approaches. In other words, the following inverse problem is solved: given the measured overall thermal conductivities of composite soil find the probability density function f(λ for each soil separate. For that purpose, measured thermal conductivities of 32 soils (of various fabric compositions at saturation are used. Recovered functions f(λ are then applied to the computational micromechanics approach; predicted conductivities are in a good agreement with laboratory results.
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
Liu, Hongxue; Lu, Jiwei; Wolf, Stuart; Hodgson, Jim; Rutgers, Maarten
2013-01-01
We demonstrate a versatile variable field module (VFM) with capability of both field and angular dependent measurements up to 1800 Oe for scanning probe system. The magnetic field strength is changed by adjusting the distance between a rare earth magnet and the probe tip and is monitored in-situ by a built-in Hall sensor. Rotating the magnet allows the field vector to change from the horizontal to vertical direction and makes it possible to do angular dependent measurements. The capability of the VFM system is demonstrated by degaussing a floppy disk media with increasing magnetic field. Angular dependent measurements clearly show the evolution of magnetic domain structures, with a completely reversible magnetic force microscopy phase contrast observed when the magnetic field is rotated by 180{\\deg}. A further demonstration of out-of-plane and in-plane magnetic switching of CoFe2O4 pillars in CoFe2O4-BiFeO3 nanocomposites was presented and discussed.
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...
Chaotic Size Dependence in the Ising Model with Random Boundary Conditions
Enter, A.C.D. van; Medved’, I.; Netočný, K.
2002-01-01
We study the nearest-neighbour Ising model with a class of random boundary conditions, chosen from a symmetric i.i.d. distribution. We show for dimensions 4 and higher that almost surely the only limit points for a sequence of increasing cubes are the plus and the minus state. For d=2 and d=3 we pro
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.
Institute of Scientific and Technical Information of China (English)
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.
Difference prophet inequalities for [0,1] -valued i.i.d. random variables with cost for observations
Kosters, Holger
2004-01-01
Let X1,X2,… be a sequence of [0,1]-valued i.i.d. random variables, let c≥0 be a sampling cost for each observation and let Yi=Xi−ic, i=1,2,…. For n=1,2,…, let M(Y1,…,Yn)=E(max 1≤i≤nYi) and V(Y1,…,Yn)=sup τ∈CnE(Yτ), where Cn denotes the set of all stopping rules for Y1,…,Yn. Sharp upper bounds for the difference M(Y1,…,Yn)−V(Y1,…,Yn) are given under various restrictions on c and n.
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...
Directory of Open Access Journals (Sweden)
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.
Institute of Scientific and Technical Information of China (English)
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.
DEFF Research Database (Denmark)
Jacobsen, S.; Andersen, P.H.; Tølbøll, T.;
2004-01-01
In order to investigate the dose dependency and the individual variability of the lipopolysaccharide (LPS)-induced acute phase protein response in cattle, 8 nonlactating, nonpregnant Danish Holstein cows were challenged 3 times each by intravenous injection of increasing doses (10, 100, and 1000 ng....../kg, consecutively) of Escherichia coli LPS with 3-wk intervals. All 3 LPS doses resulted in a rapid increase in serum concentrations of haptoglobin and serum amyloid A (SAA) and a decrease in serum concentrations of albumin in all 8 cows. Serum concentrations of acute phase proteins (APP) remained altered...... and haptoglobin concentrations in either of the challenges, which suggests that the synthesis of haptoglobin and SAA are regulated in different ways. In conclusion, cattle are highly susceptible to LPS, as very low doses of LPS elicited acute phase albumin, SAA, and haptoglobin responses. Concentrations of APP...
Complexity of two-variable Dependence Logic and IF-Logic
Kontinen, Juha; Lohmann, Peter; Virtema, Jonni
2011-01-01
We study the two-variable fragments D^2 and IF^2 of dependence logic and independence-friendly logic. We consider the satisfiability and finite satisfiability problems of these logics and show that for D^2, both problems are NEXPTIME-complete, whereas for IF^2, the problems are undecidable. We also show that D^2 is strictly less expressive than IF^2 and that already in D^2, equicardinality of two unary predicates and infinity can be expressed (the latter in the presence of a constant symbol). This is an extended version of a publication in the proceedings of the 26th Annual IEEE Symposium on Logic in Computer Science (LICS 2011).
Lv, Geli; Huang, Dazu; Guo, Ying
2016-05-01
The intensities of signal and local oscillator (LO) can be elegantly manipulated for the noise-based quantum system while manipulating the wavelength-dependent modulation in source to increase the performance of the continuous-variable key distribution in terms of the secret key rate and maximal transmission distance. The source-based additional noises can be tuned and stabilized to the suitable values to eliminate the effect of the LO fluctuations and defeat the potential attacks in imperfect quantum channels. It is firmly proved that the secret key rate can be manipulated in source over imperfect channels by the intensities of signal and LO with different wavelengths, which have an effect on the optimal signal-to-noise ratio of the heterodyne detectors resulting from the detection efficiency and the additional electronic noise as well. Simulation results show that there is a nice balance between the secret key rate and the maximum transmission distance.
Cast microstructure of Inconel 713C and its dependence on solidification variables
Energy Technology Data Exchange (ETDEWEB)
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.
Directory of Open Access Journals (Sweden)
Jorge, N.
1996-04-01
Full Text Available Experiments were carried out in the absence of food to define the influence of significant variables of the frying process, i.e. oil unsaturation, temperature, surface-to-oil volume ratio, type of heating and dimethylpolysiloxane (DMPS addition. Special emphasis was placed on clarifying the action of the addition of low concentrations of DMPS to frying oils. From statistical evaluation based on the content of polar compounds, the strong influence of the variables surface-to-oil volume ratio, DMPS addition and oil unsaturation was deduced. However, changes due to 10ºC difference in temperature were not significant. Analysis of two-way interactions demonstrated that interactions between type of heating/DMPS addition, type of heating/oil unsaturation, surface-to-oil volume ratio/DMPS addition and surface-to-oiI volume ratio/oil unsaturation were significant, thus indicating the complexity of the frying process. Finally, it was found that increase in specific groups of compounds formed through oxidative polymerization as well as loss of natural antioxidants depended mainly on the total content of polar compounds and, at a second level, on the oil unsaturation.
Sharma, A K; Mendki, M J; Tikar, S N; Chandel, K; Sukumaran, D; Parashar, B D; Veer, Vijay; Agarwal, O P; Prakash, Shri
2009-10-01
Genetic variability and environmental factors may influence the refractiveness, propagation of pathogen and transmission of disease. Random amplified polymorphic DNA (RAPD) is one of the widely used molecular markers for population genetic diversity studies. In present study, RAPD is used to ascertain the genetic variability in Culex quinquefasciatus populations collected from various Indian geographical locations. Out of 50 RAPD primers screened, 14 primers exhibited clear, concrete and distinct banding pattern showing up to 100% polymorphism. Primer OPBD3 was tested with DNA of 14 geographical populations from India (including one laboratory population) showed 21 loci representing 14 populations with 100% polymorphism. The genetic diversity among the populations indicated the Shannon index (I) and gene diversity index (H(ST)), 0.48 and 0.31, respectively among the population, displaying rich genetic variation among the Cx. quinquefasciatus populations. Consensus tree showed two clusters indicating the genetic variation among the various geographical populations. The findings of this study may be useful to understand the population variation under different ecological conditions and development of effective vector management strategies. PMID:19577531
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
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.
Radial dependence of line profile variability in seven O9--B0.5 stars
Martins, F.; Marcolino, W.; D. J. Hillier; 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 Bernar...
Borges, R. R.; Borges, F. S.; Lameu, E. L.; Batista, A. M.; Iarosz, K. C.; Caldas, I. L.; Viana, R. L.; Sanjuán, M. A. F.
2016-05-01
In this paper, we study the effects of spike timing-dependent plasticity on synchronisation in a network of Hodgkin-Huxley neurons. Neuron plasticity is a flexible property of a neuron and its network to change temporarily or permanently their biochemical, physiological, and morphological characteristics, in order to adapt to the environment. Regarding the plasticity, we consider Hebbian rules, specifically for spike timing-dependent plasticity (STDP), and with regard to network, we consider that the connections are randomly distributed. We analyse the synchronisation and desynchronisation according to an input level and probability of connections. Moreover, we verify that the transition for synchronisation depends on the neuronal network architecture, and the external perturbation level.
Landrum, Carla Jill
There is a shared desire among public and private sectors to produce more reliable predictions, accurate mapping, and appropriate scaling of soil moisture and associated parameters across landscapes. A discrepancy often exists between the scale at which soil hydrologic properties are measured and the scale at which they are modeled for management purposes. Moreover, little is known about the relative importance of hydrologic modeling parameters as soil moisture fluctuates with time. More research is needed to establish which observation scales in space and time are optimal for managing soil moisture variation over large spatial extents and how these scales are affected by fluctuations in soil moisture content with time. This research fuses high resolution geoelectric and light detection and ranging (LiDAR) as auxiliary measures to support sparse direct soil sampling over a 40 hectare inner BluegrassKentucky (USA) landscape. A Veris 3100 was used to measure shallow and deep apparent electrical conductivity (aEC) in tandem with soil moisture sampling on three separate dates with ascending soil moisture contents ranging from plant wilting point to near field capacity. Terrain attributes were produced from 2010 LiDAR ground returns collected at ≤1 m nominal pulse spacing. Exploratory statistics revealed several variables best associate with soil moisture, including terrain features (slope, profile curvature, and elevation), soil physical and chemical properties (calcium, cation exchange capacity, organic matter, clay and sand) and aEC for each date. Multivariate geostatistics, time stability analyses, and spatial regression were performed to characterize scale-dependent soil moisture patterns in space with time to determine which soil-terrain parameters influence soil moisture distribution. Results showed that soil moisture variation was time stable across the landscape and primarily associated with long-range (˜250 m) soil physicochemical properties. When the soils
Directory of Open Access Journals (Sweden)
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.
Guigues, Vincent
2014-01-01
We consider a random variable expressed as the Euclidean distance between an arbitrary point and a random variable uniformly distributed in a closed and bounded set of a three-dimensional Euclidean space. Four cases are considered for this set: a union of disjoint disks, a union of disjoint balls, a union of disjoint line segments, and the boundary of a polyhedron. In the first three cases, we provide closed-form expressions of the cumulative distribution function and the density. In the last...
Energy Technology Data Exchange (ETDEWEB)
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.
The Dependence of Cloud Particle Size on Non-Aerosol-Loading Related Variables
Energy Technology Data Exchange (ETDEWEB)
Shao, H.; Liu, G.
2005-03-18
An enhanced concentration of aerosol may increase the number of cloud drops by providing more cloud condensation nuclei (CCN), which in turn results in a higher cloud albedo at a constant cloud liquid water path. This process is often referred to as the aerosol indirect effect (AIE). Many in situ and remote sensing observations support this hypothesis (Ramanathan et al. 2001). However, satellite observed relations between aerosol concentration and cloud drop size are not always in agreement with the AIE. Based on global analysis of cloud effective radius (r{sub e}) and aerosol number concentration (N{sub a}) derived from satellite data, Sekiguchi et al. (2003) found that the correlations between the two variables can be either negative, or positive, or none, depending on the location of the clouds. They discovered that significantly negative r{sub e} - N{sub a} correlation can only be identified along coastal regions of the continents where abundant continental aerosols inflow from land, whereas Feingold et al. (2001) found that the response of r{sub e} to aerosol loading is the greatest in the region where aerosol optical depth ({tau}{sub a}) is the smallest. The reason for the discrepancy is likely due to the variations in cloud macroscopic properties such as geometrical thickness (Brenguier et al. 2003). Since r{sub e} is modified not only by aerosol but also by cloud geometrical thickness (H), the correlation between re and {tau}{sub a} actually reflects both the aerosol indirect effect and dependence of H. Therefore, discussing AIE based on the r{sub e}-{tau}{sub a} correlation without taking into account variations in cloud geometrical thickness may be misleading. This paper is motivated to extract aerosols' effect from overall effects using the independent measurements of cloud geometrical thickness, {tau}{sub a} and r{sub e}.
Karpyak, Victor M; Romanowicz, Magdalena; Schmidt, John E; Lewis, Kriste A; Bostwick, John M
2014-01-01
Heart rate variability (HRV) is an objective and sensitive measure of integrated physiological functioning reflective of heart rhythm responsivity to internal and external demands. Reduced HRV is associated with vulnerability to stress and deterioration of medical and/or psychiatric conditions, while increased HRV is associated with a favorable treatment response and recovery from various medical and/or psychiatric conditions. Our previous review found that acute alcohol consumption caused decreased parasympathetic and increased sympathetic HRV effects in both nonalcoholic and chronic alcohol users. This review investigates the effects of chronic alcohol consumption on HRV in alcohol-dependent subjects and nondependent users. MEDLINE, Scopus, and PubMed were searched for human experimental and clinical trials that measured the effects of chronic alcohol use on HRV. Only publications that included a description of their study designs and clearly stated methodologies for data collections, and outcome measures were reviewed. We have reviewed a total of 24 articles. In nondependent users, low dose (approximating the recommended daily amount of 1 standard drink in women and 2 in men) use is associated with increased HRV parameters compared to those who drink less frequently or abstain altogether. A further increase in consumption is associated with decreased HRV compared to both abstainers and more moderate drinkers. HRV changes during withdrawal generally follow the same negative direction but are more complex and less understood. In dependent subjects, an improvement in HRV was seen following abstinence but remained reduced compared to nonalcoholic controls. This review demonstrates that HRV changes associated with chronic use follow a J-shaped curve. It supports recommendations that limit daily alcohol intake to no more than 2 drinks for men and 1 drink for women. Future studies should investigate HRV as a biomarker of alcoholism development and treatment response as
López, M. G.; Moro, M. A.; Castillo, C. F.; Artalejo, C. R.; García, A. G.
1989-01-01
1. Catecholamine release from cat adrenal glands perfused at a high rate (4 ml min-1) at 37 degrees C with modified Krebs solutions lacking Ca and containing 1.2 mM K (hyperpolarizing solution) or 118 mM K (depolarizing solution) was triggered by 10-s pulses of Ca (0.5 mM) in the presence of 118 mM K. Hyperpolarized glands released 1280 +/- 135 ng per pulse and depolarized glands 831 +/- 98 ng per pulse (n = 29). 2. While the dihydropyridine Ca channel blocker nitrendipine inhibited secretion in hyperpolarized glands with an IC50 of 214 nM, in depolarizing conditions the drug was much more potent (IC50 = 0.99 nM). In contrast, the inorganic Ca channel blocker cadmium inhibited secretion with the same potency both in hyperpolarized or depolarized glands. 3. Cinnarizine, diltiazem and verapamil exhibited intermediate degrees of voltage-dependence in blocking secretion. The IC50 ratios between hyperpolarized and depolarized glands were 215, 36, 19, 8 and 0.76 respectively for nitrendipine, cinnarizine, diltiazem, verapamil and cadmium. Because the experimental design (strong depolarization in the absence of Ca) favours the highest opening probability of Ca channels, it seems that these drugs bind preferentially to their receptors when these channels are in their open state. 4. Variable voltage-dependent effects of the five Ca channel blockers on adrenomedullary catecholamine release suggests different sites and mechanisms of action on, or near L-type Ca channels in chromaffin cells. In addition, these findings might help to explain why these drugs exhibit tissue selectivity and why they act differently in normal polarized as compared to ischaemic depolarized cells. PMID:2720300
Precise Asymptotics for Random Matrices and Random Growth Models
Institute of Scientific and Technical Information of China (English)
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.
Spectral Variability of Quasars in the Sloan Digital Sky Survey. I: Wavelength Dependence
Wilhite, B C; Kron, R G; Schneider, D P; Pereyra, N; Brunner, R J; Richards, G T; Brinkmann, J; Wilhite, Brian C.; Berk, Daniel E. Vanden; Kron, Richard G.; Schneider, Donald P.; Pereyra, Nicholas; Brunner, Robert J.; Richards, Gordon T.; Brinkmann, Jonathan V.
2005-01-01
Sloan Digital Sky Survey (SDSS) repeat spectroscopic observations have resulted in multiple-epoch spectroscopy for roughly 2500 quasars observed more than 50 days apart. From this sample, we identify 315 quasars that have varied significantly between observations. We create an ensemble difference spectrum (bright phase minus faint phase) covering rest-frame wavelengths from 1000 to 6000 Angstroms. This average difference spectrum is bluer than the average single-epoch quasar spectrum; a power-law fit to the difference spectrum yields a spectral index alpha_lambda = -2.00, compared to an index of alpha_lambda = -1.35 for the single-epoch spectrum. The strongest emission lines vary only 30% as much as the continuum. Due to the lack of variability of the lines, measured photometric color is not always bluer in brighter phases, but depends on redshift and the filters used. Lastly, the difference spectrum is bluer than the ensemble quasar spectrum only for lambda_rest < 2500 Angstroms, indicating that the varia...
Energy-dependent variability and the origin of the soft X-ray excess in AGN
Gierlinski, M; Done, Chris; Gierlinski, Marek
2006-01-01
The origin of the soft excess seen in many AGN below ~1 keV is still an unsolved problem. It is unlikely to represent a true continuum component as its characteristic 'temperature' shows a remarkable constancy over a wide range of AGN luminosity and black hole mass. This instead favours an association with atomic processes, in particular with the increase in opacity between 0.7-2 keV associated with partially ionized O and Fe. The opacity jump can give rise to a soft excess either through reflection or transmission, and both scenarios can fit the spectra equally well as long as there is strong velocity shear to smear out the characteristic narrow atomic features. Here we use orthogonal constraints from the energy-dependent variability. The rms spectra seen in XMM-Newton AGN data often show a broad peak between 0.7-2 keV. We show that the absorption model can explain the data well if the ionization state of the smeared absorption responds to luminosity changes in the continuum.
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.
Radial dependence of line profile variability in seven O9-B0.5 stars
Martins, F.; Marcolino, W.; Hillier, D. J.; Donati, J.-F.; Bouret, J.-C.
2015-02-01
Context. Massive stars show a variety of spectral variabilities: discrete absorption components in UV P-Cygni profiles, optical line profile variability, X-ray variability, and radial velocity modulations. Aims: 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 and on high signal-to-noise ratio optical spectra collected with the spectrograph NARVAL on the Télescope Bernard Lyot at Pic du Midi. Methods: We investigated the variability of twelve spectral lines by means of the temporal variance spectrum. The selected lines probe the radial structure of the atmosphere from the photosphere to the outer wind. We also performed a spectroscopic analysis with atmosphere models to derive the stellar and wind properties and to constrain the formation region of the selected lines. Results: We show that variability is observed in the wind lines of all bright giants and supergiants on a daily timescale. Lines formed in the photosphere are sometimes variable, sometimes not. The dwarf stars do not show any sign of variability. If variability is observed on a daily timescale, it can also (but not always) be observed on hourly timescales, albeit with lower amplitude. There is a very clear correlation between amplitude of the variability and fraction of the line formed in the wind. Strong anti-correlations between the different parts of the temporal variance spectrum are observed. Conclusions: Our results indicate that variability is stronger in lines formed in the wind. A link between photospheric and wind variability is not obvious from our study, since wind variability is observed regardless of the level of photospheric variability. Different photospheric lines also show different degrees of variability. Appendices are available in electronic form at http://www.aanda.org
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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.
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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.
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
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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
Continuous infusion of propofol at variable rates in a time dependent in cats
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Felipe Comassetto
2015-04-01
Full Text Available Felines biotransforms propofol slowly developing cumulative effect. The aim this study was to develop a scheme of continuous infusion of propofol at time dependent variable rate in cats. Sixteen healthy female cats undergoing elective ovariohysterectomy and received as premedication dexmedetomidine (2.5 ?g/kg, methadone (0.5 mg/kg and ketamine (0.5 mg/kg administrated at intramuscular rote. After 15 minutes , the animals were allocated into two groups : Fixed Rate (GFR, which received propofol 4mg/kg, followed by continuous infusion (CI at the rate of 0.3 mg/kg/min for 60 minutes; and Variable Rate (GVR receiving the same induction protocol exchange with the IC starting at 0.3 mg/ kg/min for 10 minutes, 0.25 mg/kg/min up to 25 minutes, 0.2 mg/ kg/min up to 45 minutes and 0.15 mg/kg /min to 60 min of infusion based on simulation STAMPUMP®. We evaluated the cardiac frequency (HR, respiratory rate (RR, systolic blood pressure (SBP and maintenance of anesthesia during 60 minutes of infusion , as well as time to extubation, sternal recumbency and to full recovery. We observed similar anesthesia in both groups, but the GVR was used propofol least 30% for maintenance anesthesia. There was a reduction of HR and f in both groups after induction, with one animal the GFR developed apnea during all periods evaluated . Decreased SBP in GFR at all times in relation to the baseline, as the GVR, SBP decreased in just a moment. There was no significant difference between groups with respect to time to extubation (GFR 43.2 ± 19.5 min and 30.7 ± 13.2 min GVR , deambulation ( GFR 60.7 ± 29.6 min and 41.6 ± GVR 17.2 min and total recovery (GFR 136 ± 34.3 min and 101.5 ± 29.6 min GVR . We conclude that the two techniques keeps similar anesthetic plans, being safe for use in cats, and that the rate has varied propofol consumption 30 % lower.
Alaskan soil carbon stocks: spatial variability and dependence on environmental factors
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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
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
Institute of Scientific and Technical Information of China (English)
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).
A Strong Limit Theorem on Generalized Random Selection for m-valued Random Sequences
Institute of Scientific and Technical Information of China (English)
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.
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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.
A Strong Logarithmic Law for Arrays of Random Variables%随机变量阵列的一个强大数律
Institute of Scientific and Technical Information of China (English)
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。
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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.
The derivative-dependent functional variable separation for the evolution equations
Institute of Scientific and Technical Information of China (English)
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.
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Azarekhsh Mokri
2009-08-01
Full Text Available Introduction: In this research, researchers want to study the effectiveness of Olanzapine on reduction of substance abuse relapse among people who are dependent to opioid material, merely. Method: A randomized clinical trial was designed. The population was opioid dependence subjects (only men that were diagnosed based on DSM-IV TR criteria, and referred to national center of addiction studies clinic. Detoxification was done by using of Clonidine, Clonazepam, Disiklomin, and NSAIDS within7 through 10 days. In second stage, the Patients who were referred to the clinic those men who had satisfied criterions selected. Demographic forms, testimonial certificate, Addiction Severity Index, Beck Depression Questionnaire, Zung Self report anxiety test administered among selected sample. Sample divided to two groups (placebo and Olanzapine the research last for 8 weeks. Results: the results showed that addiction severity reduced in both groups, but there was not significant difference in reduction of addiction severity between two groups. There was significant difference in depression and anxiety among mean scores of base line and follow up in both groups but there was not significant difference between two groups in follow up measures. Conclusion: Altogether, the results did not confirm the effectiveness of Olanzapine on maintenance treatment of opioid dependence.
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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.
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Keita eMitani
2016-06-01
Full Text Available The processing of time intervals is fundamental for sensorimotor and cognitive functions. Perceptual and motor timing are often performed concurrently (e.g., playing a musical instrument. Although previous studies have shown the influence of body movements on time perception, how we perceive self-produced time intervals has remained unclear. Furthermore, it has been suggested that the timing mechanisms are distinct for the sub- and suprasecond ranges. Here, we compared perceptual performances for self-produced and passively presented time intervals in random contexts (i.e., multiple target intervals presented in a session across the sub- and suprasecond ranges (Experiment 1 and within the sub- (Experiment 2 and suprasecond (Experiment 3 ranges, and in a constant context (i.e., a single target interval presented in a session in the sub- and suprasecond ranges (Experiment 4. We show that self-produced time intervals were perceived as shorter and more variable across the sub- and suprasecond ranges and within the suprasecond range but not within the subsecond range in a random context. In a constant context, the self-produced time intervals were perceived as more variable in the suprasecond range but not in the subsecond range. The impairing effects indicate that motor timing interferes with perceptual timing. The dependence of impairment on temporal contexts suggests multiple timing mechanisms for the subsecond and suprasecond ranges. In addition, violation of the scalar property (i.e., a constant variability to target interval ratio was observed between the sub- and suprasecond ranges. The violation was clearer for motor timing than for perceptual timing. This suggests that the multiple timing mechanisms for the sub- and suprasecond ranges overlap more for perception than for motor. Moreover, the central tendency effect (i.e., where shorter base intervals are overestimated and longer base intervals are underestimated disappeared with subsecond
Mitani, Keita; Kashino, Makio
2016-01-01
The processing of time intervals is fundamental for sensorimotor and cognitive functions. Perceptual and motor timing are often performed concurrently (e.g., playing a musical instrument). Although previous studies have shown the influence of body movements on time perception, how we perceive self-produced time intervals has remained unclear. Furthermore, it has been suggested that the timing mechanisms are distinct for the sub- and suprasecond ranges. Here, we compared perceptual performances for self-produced and passively presented time intervals in random contexts (i.e., multiple target intervals presented in a session) across the sub- and suprasecond ranges (Experiment 1) and within the sub- (Experiment 2) and suprasecond (Experiment 3) ranges, and in a constant context (i.e., a single target interval presented in a session) in the sub- and suprasecond ranges (Experiment 4). We show that self-produced time intervals were perceived as shorter and more variable across the sub- and suprasecond ranges and within the suprasecond range but not within the subsecond range in a random context. In a constant context, the self-produced time intervals were perceived as more variable in the suprasecond range but not in the subsecond range. The impairing effects indicate that motor timing interferes with perceptual timing. The dependence of impairment on temporal contexts suggests multiple timing mechanisms for the subsecond and suprasecond ranges. In addition, violation of the scalar property (i.e., a constant variability to target interval ratio) was observed between the sub- and suprasecond ranges. The violation was clearer for motor timing than for perceptual timing. This suggests that the multiple timing mechanisms for the sub- and suprasecond ranges overlap more for perception than for motor. Moreover, the central tendency effect (i.e., where shorter base intervals are overestimated and longer base intervals are underestimated) disappeared with motor timing within the
Peter M Spieth; Güldner, Andreas; Uhlig, Christopher; Bluth, Thomas; Kiss, Thomas; Schultz, Marcus J.; Pelosi, Paolo; Koch, Thea; Gama de Abreu, Marcelo
2014-01-01
Background General anesthesia usually requires mechanical ventilation, which is traditionally accomplished with constant tidal volumes in volume- or pressure-controlled modes. Experimental studies suggest that the use of variable tidal volumes (variable ventilation) recruits lung tissue, improves pulmonary function and reduces systemic inflammatory response. However, it is currently not known whether patients undergoing open abdominal surgery might benefit from intraoperative variable ventila...
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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
Bornstein, Robert F.
2007-01-01
Presents a reply by Robert Bornstein to comments from Chronister and regarding his article, "The complex relationship between dependency and domestic violence: Converging psychological factors and social forces." In addition to raising some important issues regarding the link between dependency and domestic violence, the comments by Chronister and…
Ortega, M.; Bunce, R.G.H.; Barrio, del J.M.G.; Elena-Rossello, R.
2008-01-01
The analysis of the dependence of landscape patterns on environment was carried out in order to investigate the landscape structure evolution of Spain. The underlying concept was that the dependence between landscape spatial structure and environmental factors could be gradually decreasing over time
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
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
张永进; 汪忠志
2016-01-01
应用正交变换将对称矩阵对角化，基于随机向量正交变换后独立性的不变性及矩阵迹相关性质，给出一个关于对称矩阵经随机变换后方差的证明，并将该结论推广到更一般情形。%Based on the Theorem in a reference book, a symmetric matrix is diagonalized by orthogonal transformation first. Because of the invariance property of independence when a random variable is transformed through orthogonal mean, a proof for variance of random variable after stochastic transformation of symmetric matrix is presented by applying the property of trace of matrix. Secondly, a general conclusion for the theorem is studied.
Energy Technology Data Exchange (ETDEWEB)
Choi, Seon Soon [Sahmyook University, Seoul (Korea, Republic of)
2015-01-15
The primary aim of this paper is to evaluate the probabilistic fatigue crack propagation models using the residual of a random variable and to present the probabilistic model fit for the probabilistic fatigue crack growth behavior in Mg-Al-Zn alloys under maximum load conditions. The models used in this study were prepared by applying a random variable to empirical fatigue crack propagation models such as the Paris-Erdogan model, Walker model, Forman model, and modified Forman model. It was verified that the good models for describing the stochastic variation of the fatigue crack propagation behavior in Mg-Al-Zn alloys under maximum load conditions were the ‘probabilistic Paris-Erdogan model’ and ‘probabilistic Walker model’. The influence of the maximum load conditions on the stochastic variation of fatigue crack growth is also considered.
Nakahara, Kenji
2012-01-01
We show uniform estimates for distributions of the sum of i.i.d. random variables in the threshold case. Rozovskii showed several uniform estimates but the speed of convergence was not known. Our main uniform estimate implies a speed of convergence. We also compare our estimates with Nagaev's estimate which is valid in the non-threshold case and, moreover, give a necessary and sufficient condition for Nagaev's estimate to hold in the threshold case.
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.
Liu, Shijing; Lane, Scott D.; Schmitz, Joy M.; Green, Charles E.; Cunningham, Kathryn A.; Moeller, F. Gerard
2011-01-01
Neuroimaging data suggest that impaired performance on response inhibition and information processing tests in cocaine-dependent subjects is related to prefrontal and frontal cortical dysfunction and that dysfunction in these brain areas may underlie some aspects of cocaine addiction. In subjects with attention-deficit hyperactivity disorder and other psychiatric disorders, the Intra-Individual Reaction Time Variability (IIRTV) has been associated with frontal cortical dysfunction. In the pre...
Hoang, Hanh H.; Nickerson, Nicholas N.; Lee, Vincent T.; Kazimirova, Anastasia; Chami, Mohamed; Pugsley, Anthony P.; Lory, Stephen
2011-01-01
ABSTRACT In Gram-negative bacteria, the Lol and Bam machineries direct the targeting of lipidated and nonlipidated proteins, respectively, to the outer membrane (OM). Using Pseudomonas aeruginosa strains with depleted levels of specific Bam and Lol proteins, we demonstrated a variable dependence of different OM proteins on these targeting pathways. Reduction in the level of BamA significantly affected the ability of the β-barrel membrane protein OprF to localize to the OM, while the targeting...
Energy Technology Data Exchange (ETDEWEB)
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%.
Directory of Open Access Journals (Sweden)
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
Lloret Cabot, M.; Hicks, M.A.; Van den Eijnden, A.P.
2012-01-01
Spatial variability of soil properties is inherent in soil deposits, whether as a result of natural geological processes or engineering construction. It is therefore important to account for soil variability in geotechnical design in order to represent more realistically a soil’s in situ state. This
De Ruiter, Naomi M. P.; Den Hartigh, Ruud J. R.; Cox, Ralf F. A.; Van Geert, Paul L. C.; Kunnen, E. Saskia
2015-01-01
Research regarding the variability of state self-esteem (SSE) commonly focuses on the magnitude of variability. In this article we provide the first empirical test of the temporalstructure of SSE as a real-time process during parent-adolescent interactions. We adopt a qualitative phenomenological ap
Time-dependent excitation and ionization modelling of absorption-line variability due to GRB080310
DEFF Research Database (Denmark)
Vreeswijk, P.M.; De Cia, A.; Jakobsson, P.;
2013-01-01
We model the time-variable absorption of Feii, Feiii, Siii, Cii and Crii detected in Ultraviolet and Visual Echelle Spectrograph (UVES) spectra of gamma-ray burst (GRB) 080310, with the afterglow radiation exciting and ionizing the interstellar medium in the host galaxy at a redshift of z = 2.427...... ionized by the radiation released during the first few tens of minutes after the GRB. © 2012 ESO....
International Nuclear Information System (INIS)
We review the recent progress in our understanding of the effect of B-site randomness on Pb(In1/2Nb1/2)O3 (PIN) from the experimental and theoretical viewpoints. PIN is one of the ideal systems for investigating the effect of perovskite B-site randomness on relaxor formation, because it can be in the antiferroelectric (AFE), ferroelectric (FE), or relaxor state depending on B-site randomness. Lattice dynamics measured in ordered and disordered PINs indicates the existence of FE instability regardless of the B-site randomness of PIN. AFE is stabilized when the B-site is spatially ordered, overwhelming FE instability. The hidden FE state starts to appear as B-site randomness becomes stronger and suppresses AFE instability. Ultimately, the randomness competes with the development of FE regions and blocks long-range FE ordering, which yields polar nanoregions (PNRs) resulting in relaxor behavior. In order to investigate the interesting behavior of PIN, we constructed a minimal model that includes dipolar interaction and easy-axis anisotropy which depends on B-site randomness. The results from Monte Carlo simulations show that the model well reproduces the phase diagram and dielectric constant of PIN qualitatively. (author)
Field Dependence-Independence as a Variable in Second Language Cloze Test Performance.
Hansen, Jacqueline; Stansfield, Charles
This paper explores the influence of field independent-dependent cognitive style on second language test performance, especially as it relates to performance on the integrative type of measure known as the cloze test. Approximately 250 college students enrolled in a first semester Spanish course formed the sample group for this correlational…
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…
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.
Dezocine attenuates fentanyl-induced cough in a dose-dependent manner-a randomized controlled trial
Xu, Yajun; Zhu, Yun; Wang, Shilai; Ren, Yu; Miao, Changhong
2015-01-01
Fentanyl-induced cough (FIC) should be effectively prevented in patients requiring stable induction of general anesthesia. Our study was to evaluate the suppressive effects of different doses of intravenous dezocine on FIC during the induction of general anesthesia. A total of 400 patients of American Society of Anesthesiologists (ASA) physical status I and II were randomized into four groups (n = 100). Right before Fentanyl bolus, the four groups were given intravenously a matching placebo (group I) (equal volume of 0.9% saline), dezocine 0.025 mg/kg (group II), 0.05 mg/kg (group III), and 0.1 mg/kg (group IV), respectively. Patients were induced with fentanyl 3 µg/kg and the injection time of fentanyl was less than 5 s in all patients. The occurrence of cough was recorded 2 min after fentanyl bolus. The incidence of FIC was 40% in group I, 12% in group II, 4% in group III, and 0 in group IV. Group I had significantly higher incidence of FIC than Groups II, III and IV (P < 0.05). Group IV had lower incidence of FIC than Groups II (0% vs 12%; P = 0.0003) and III (0% vs 4%; P = 0.043). Our study showed that intravenous dezocine reduced the incidence of FIC during anesthetic induction. The suppressive effect was dose-dependent. PMID:26131209
On Conditional Simple Random Sample
Wywiał, Janusz L.
2014-01-01
Estimation of the population average in a finite and fixed population on the basis of the conditional simple random sampling design dependent on order statistics of the auxiliary variable is studied. The sampling scheme implementing the sampling design is proposed. The inclusion probabilities are derived. The well known Horvitz-Thompson statistic under the conditional simple random sampling designs is considered as the estimator of population mean. Moreover, it was shown that the Horvitz-Thom...
Brown, J M; Stratmann, G; Cowley, D M; Mottram, B M; Chalmers, A H
1987-07-01
Twenty-two recurrent calcium stone formers had 24-h urinary oxalate excretions on their home diets which were significantly greater than those of 30 normal subjects (0.48 +/- 0.23 mmol/d; mean +/- SD compared with 0.31 +/- 0.11; P less than 0.01). The stone formers also demonstrated marked day to day variability in oxalate excretion indicating that a single normal urinary oxalate measurement did not exclude significant hyperoxaluria at other times. On a hospital diet containing 1000 mg calcium per day, urinary oxalate excretion fell significantly from 0.48 +/- 0.23 mmol/d to 0.32 +/- 0.12; P less than 0.01. As the urinary calcium excretion in and out of hospital was similar, it seems unlikely that low calcium intake at home was responsible for the hyperoxaluria. All patients had recurrent symptomatic stone disease and had been advised to avoid foods rich in oxalate. Whilst poor compliance is a possible explanation for the variability in oxalate excretion, we believe it is more likely that there is an inadvertent intake of oxalogenic precursors in their diet. As normal subjects do not demonstrate hyperoxaluria on similar home diets, stone formers may have a metabolic defect in the handling of these precursors. PMID:3662388
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.
Khoubrouy, Soudeh A; Panahi, Issa M S
2011-01-01
Various methods have been proposed to overcome the problem of compensating the acoustic feedback path that negatively impacts the performance of hearing aid devices. However, in most of them feedback path model is assumed to be fixed which is not quite realistic. In this paper, we consider fixed and variable feedback paths and analyze for each case the performance of one of the robust Adaptive Feedback Cancellation (AFC) schemes, i.e. the Prediction Error Method AFC which uses Partitioned Block Frequency-Domain Normalized Least Mean Square (PBFD-NLMS) algorithm. Based on the analysis results we propose varying the step size values for the same adaptive algorithm on the fly by monitoring the misalignment criteria. The experimental results using the proposed method show improvement made on the system performance. PMID:22256175
Amei, Amei; Sawyer, Stanley
2010-01-01
We derive a Poisson random field model for population site polymorphisms differences within and between two species that share a relatively recent common ancestor. The model can be either equilibrium or time inhomogeneous. We first consider a random field of Markov chains that describes the fate of a set of individual mutations. This field is approximated by a Poisson random field from which we can make inferences about the amounts of mutation and selection that have occurred in the history o...
Boezen, H M; Postma, D S; Schouten, J P; Kerstjens, H A; Rijcken, B
1996-07-01
We investigated the coherence of bronchial hyperresponsiveness (BHR) and peak expiratory flow (PEF) variability in their relation to allergy markers and respiratory symptoms in 399 subjects (20-70 yr). Bronchial hyperresponsiveness to methacholine was defined by both the provocative dose causing a fall in FEV1 of 20%, and the dose-response slope. PEF variability was determined as diurnal PEF variation (amplitude percent mean) and between-day PEF variation. Skin tests positivity, serum total IgE, and specific IgE (RAST) for house-dust mite (HDM), cat, timothy grass, and birch ("pollen") were determined, as well as the number of peripheral blood eosinophils. Wheeze and nocturnal dyspnea were defined as asthma-like symptoms; dyspnea > or = grade 3, cough and phlegm as chronic obstructive pulmonary disease (COPD)-like symptoms. The reciprocal of the dose-response slope and PEF variability were significantly correlated (r = -0.39). Subjects with a positive skin test for HDM (odds ratio [OR] = 3.9), cat (OR = 8.3), or pollen (OR = 3.6), or specific IgE for HDM (OR = 2.3), cat (OR = 3.4), or pollen (OR = 1.9) had increased risk of BHR compared with the reference group (all p values blood eosinophils. There are different associations of BHR and PEF variability with allergy markers. Although BHR and PEF variability are significantly correlated, they cannot be used interchangeably in epidemiologic settings. PMID:8680695
Goudarzi, Nasser
2016-04-01
In this work, two new and powerful chemometrics methods are applied for the modeling and prediction of the 19F 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 19F 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.
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...
Energy dependent power spectral states and origin of aperiodic variability in black hole binaries
Yu, Wenfei
2013-01-01
We found the black hole candidate MAXI J1659-152 showed distinct power spectra, i.e., a power-law noise (PLN) vs. band-limited noise (BLN) plus quasi-periodic oscillations (QPOs), below and above about 2 keV respectively, in the observations with the Swift and the RXTE during the 2010 outburst, indicating a high energy cut-off of the PLN and a low energy cut-off of the BLN and the QPOs around 2 keV. The emergence of the PLN and the fading of the BLN and the QPOs initially took place from below 2 keV when the source entered the hard intermediate state and finally settled in the soft state three weeks later. The evolution was accompanied by the emergence of the disk spectral component and decreases in the amplitudes of variability in the soft X-ray and the hard X-ray bands. Our results indicate that the PLN is associated with the optically thick disk in both hard and intermediate states, and power spectral state is independent of the X-ray energy spectral state in a broadband view. We suggest that in the hard a...
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.
Directory of Open Access Journals (Sweden)
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.
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
Directory of Open Access Journals (Sweden)
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.
Amei, Amei; 10.1214/09-AAP668
2010-01-01
We derive a Poisson random field model for population site polymorphisms differences within and between two species that share a relatively recent common ancestor. The model can be either equilibrium or time inhomogeneous. We first consider a random field of Markov chains that describes the fate of a set of individual mutations. This field is approximated by a Poisson random field from which we can make inferences about the amounts of mutation and selection that have occurred in the history of observed aligned DNA sequences.
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...
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. PMID:27179866
Continuous Variable Life Annuities under Fuzzy Random Environment%模糊随机环境下的连续型变额生命年金
Institute of Scientific and Technical Information of China (English)
顾建忠; 严广乐
2014-01-01
采用模糊随机理论，构建连续支付型变额生命年金模型。假定利率为三角模糊数，死亡率为随机变量。结合精算理论，给出了连续支付型变额生命年金精算现值的期望、方差以及分布函数和分位数的模糊表达式。最后，通过实证分析计算出一个在养老保险中常见的生命年金的相关值，验证模型的可行性。%This paper proposed a continuous variable life annuities model by adopting the theory of fuzzy random varia-bles,assuming that the interest rate is a triangle fuzzy number and the mortality is a random variable.Combined with the actu-ary theory,we obtained the mathematical expectation,variance,distribution,quantiles of the present value of annuities.Final-ly,we calculated these related values of a common life annuity in endowment insurance and verified the feasibility of the model with the empirical analysis.
Directory of Open Access Journals (Sweden)
Peter M Wayne
2015-06-01
Full Text Available BACKGROUND: Tai Chi (TC exercise improves balance and reduces falls in older, health-impaired adults. TC’s impact on dual task (DT gait parameters predictive of falls, especially in healthy active older adults, however, is unknown.PURPOSE: To compare differences in usual and DT gait between long-term TC-expert practitioners and age-/gender-matched TC-naïve adults, and to determine the effects of short-term TC training on gait in healthy, non-sedentary older adults. METHODS: A cross-sectional study compared gait in healthy TC-naïve and TC-expert (24.5±12 yrs experience older adults. TC-naïve adults then completed a 6-month, two-arm, wait-list randomized clinical trial of TC training. Gait speed and stride time variability (% was assessed during 90 sec trials of undisturbed and cognitive DT (serial-subtractions conditions. RESULTS: During DT, gait speed decreased (p<0.003 and stride time variability increased (p<0.004 in all groups. Cross-sectional comparisons indicated that stride time variability was lower in the TC-expert vs. TC-naïve group, significantly so during DT (2.11% vs. 2.55%; p=0.027; in contrast, gait speed during both undisturbed and DT conditions did not differ between groups. Longitudinal analyses of TC-naïve adults randomized to 6 months of TC training or usual care identified improvement in DT gait speed in both groups. A small improvement in DT stride time variability (effect size = 0.2 was estimated with TC training, but no significant differences between groups were observed. Potentially important improvements after TC training could not be excluded in this small study. CONCLUSIONS: In healthy active older adults, positive effects of short- and long-term TC were observed only under cognitively challenging DT conditions and only for stride time variability. DT stride variability offers a potentially sensitive metric for monitoring TC’s impact on fall risk with healthy older adults.
Directory of Open Access Journals (Sweden)
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.
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
International Nuclear Information System (INIS)
It is reported experimentally that low-threshold random lasing in a weakly scattering disordered structure formed by speckles using holography is achieved. It shows that the emission property of the structure is related directly to the pulse duration of the pump laser. If pumped by picosecond pulses, several spikes are observed in the emission. If pumped by a nanosecond laser, only a single dominant peak appears. The wavelength tunability of the random laser with a change in temperature has been demonstrated. The corresponding physical analyses have also been provided briefly.
Institute of Scientific and Technical Information of China (English)
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.
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.
Institute of Scientific and Technical Information of China (English)
杨欢; 邹斌
2012-01-01
采用三阶多项式正态变换方法,将非正态相关的多维随机变量变换到正态不相关的变量空间,在正态不相关的变量空间中取采样点,最后将这些采样点通过逆变换重新变换到非正态相关的变量空间中进行潮流计算。这种变换—逆变换的过程使得点估计方法能够处理含非正态相关随机变量的概率潮流问题。利用该技术,提出了一种求解包含风力发电和负荷随机性的概率潮流问题的三点估计法。基于IEEE 118节点系统的算例分析表明,该方法具有较高的精度,且计算效率高,为讨论基于相关性的概率潮流问题提供了一种有效的工具。%The third-order polynomial normal transformation （TPNT） technique was employed to transform a multivariate non-normal dependent random variables group into a multivariate standard normal independent one. Sampling points were obtained in the standard normal independent variable space and transformed into multivariate non-normal dependent ones. Incorporating three-point estimate method with TPNT technique, a TPNT-based three-point estimate method is proposed to solve probabilistic power flow problems with non-normal dependent variables. A case study on a slightly modified IEEE 118-bus system shows that, the proposed method has high accuracy and computational efficiency. It is a qualified tool to discuss the probabilistic power flow problems with non-normal dependent variables.
Using XMM-Newton to study the energy-dependent variability of H 1743-322 during its 2014 outburst
Stiele, H.; Yu, W.
2016-08-01
Black hole transients evolve during bright outbursts, showing distinct changes in their spectral and variability properties. These changes are interpreted as evidence for changes in the accretion flow and in the X-ray-emitting regions. We obtained an anticipated XMM-Newton Target of Opportunity observation of H 1743-322 during its outburst in 2014 September. Based on data from eight outbursts observed in the last 10 yr, 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 shows an energy dependence implies that the source remained 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 revealed that H 1743-322 stayed in the low-hard state during the entire outburst (known as a `failed outburst'). Here we derive the averaged QPO waveform and obtain phase-resolved spectra. A comparison of the phase-resolved spectra with the phase-averaged energy spectrum reveals spectral pivoting. We compare variability on long and short time-scales using covariance spectra and find that the covariance ratio does not show an increase towards lower energies. In other binaries an increase has been found. There are two possible explanations: either the absence of additional disc variability on longer time-scales is related to the high inclination of H 1743-322 compared with other black hole X-ray binaries, or it is the reason why we observe H 1743-322 during a failed outburst. More data on failed outbursts and on high-inclination sources will be needed in order to investigate these two possibilities further.
Directory of Open Access Journals (Sweden)
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.
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...
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
Institute of Scientific and Technical Information of China (English)
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.
Randomized random walk on a random walk
International Nuclear Information System (INIS)
This paper discusses generalizations of the model introduced by Kehr and Kunter of the random walk of a particle on a one-dimensional chain which in turn has been constructed by a random walk procedure. The superimposed random walk is randomised in time according to the occurrences of a stochastic point process. The probability of finding the particle in a particular position at a certain instant is obtained explicitly in the transform domain. It is found that the asymptotic behaviour for large time of the mean-square displacement of the particle depends critically on the assumed structure of the basic random walk, giving a diffusion-like term for an asymmetric walk or a square root law if the walk is symmetric. Many results are obtained in closed form for the Poisson process case, and these agree with those given previously by Kehr and Kunter. (author)
Directory of Open Access Journals (Sweden)
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.
DEFF Research Database (Denmark)
Asmussen, J.C.; Ibrahim, S.R.; Brincker, Rune
Abstraet Thispaper demansirates how to use the Random Decrement (RD) technique for identification o flinear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a...
DEFF Research Database (Denmark)
Asmussen, J. C.; Ibrahim, S. R.; Brincker, Rune
This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...
DEFF Research Database (Denmark)
Asmussen, J. C.; Ibrahim, R.; Brincker, Rune
1998-01-01
This paper demonstrates how to use the Random Decrement (RD) technique for identification of linear structures subjected to ambient excitation. The theory behind the technique will be presented and guidelines how to choose the different variables will be given. This is done by introducing a new...
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.
Institute of Scientific and Technical Information of China (English)
杨金英
2011-01-01
将实随机变量的条件独立性与条件回归独立性的研究推广到复随机变量,讨论了复随机变量的条件独立性、条件回归独立性及强条件独立的关系,得到了三者等价的几个充分必要条件.%This will be implemented conditional independence of random variables and conditions regressive independence extended to complex random variables, conditional independence of complex random variables, conditional regressive independence between strong conditional independence of relations is discussed,and several necessary and sufficient conditions are presented.
Muskens, O.L.; Beek, van der T.; Lagendijk, A.
2011-01-01
The frequency correlations of light in complex photonic media are of interest as a tool for characterizing the dynamical aspects of light diffusion. We demonstrate here that the frequency correlation shows a pronounced angle dependence both in transmission and in reflection geometries. Using a broad
Institute of Scientific and Technical Information of China (English)
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.
Directory of Open Access Journals (Sweden)
Harsh
2015-06-01
Full Text Available AIM: The aim of the study is to compare quetiapine with placebo along with oral naltr exone in the treatment of opioid dependent patients. We conducted the study as opioid dependence is steadily increasing in this area and more research is needed to prevent relapse after opioid detoxification. SETTINGS AND DESIGN: It is a double blind place bo controlled , randomized study that was conducted in department of psychiatry, de addiction unit (Sri Guru Ram Das Institute of Medical Sciences & Research, Sri Amritsar over one year time period. All the patients who were taken in the study had a confi rmed diagnosis of opioid dependence as per ICD 10 criteria. MATERIAL AND METHOD: It is a double blind, placebo controlled, randomized study. A total of 217 subjects were admitted over year, out of which 164 were screened as 53 subjects refused to participa te. Out of 164 randomization of 152 patient was done and two groups (1&2 were made. . During detoxification, opioids were given to both groups and stopped after 1 - 2 weeks. Then all patients were started on Naltrexone 50 mg/day. Group 1 (n=73 received nal trexone (50mg/day plus quetiapine (50 - 200mg/day, while group 2 (n=79 received naltrexone (50mg/day plus placebo (multivitamin for next 26 weeks. Our primary efficacy measures were relapse rate and percent days of abstinence . Two groups were compared w ith the help of percentage method and independent t test done. RESULTS: Relapse rate in placebo group was almost twice to that of Quetiapine group. In group 1, 24 subjects (32.87% had relapsed by the end of 6 months as compared to 56 subjects (70.88% in group 2. Percent days of abstinence in Quetiapine group were significantly higher as compared to placebo group. DISCUSSION: Our study shows significant advantages in using Quetiapine along with Naltrexone to decrease relapse rate and increase percent days of abstinence after inpatient detoxification.
Meyer, Nele; Welp, Gerhard; Amelung, Wulf
2016-04-01
Climate change is suspected to alter temperature, soil moisture, and nutrient inputs to the soil. These factors are supposed to strongly influence soil respiration. The degree by which respiration will respond to these changes is crucial for assessing future CO2 feedbacks to the atmosphere. We assume that the temperature sensitivity of soil respiration (Q10) differs spatially depending on land use, soil unit, and texture owing to their diverse properties of soil organic matter quantity and quality. We further hypothesize that the Q10 value is additionally regulated by soil moisture and nutrient status. On the basis of soil and land use maps we divided the Rur catchment (Western Germany, 2350 km²) into so called environmental soil classes (ESC) that combine each a unique combination of the factors land use, soil unit, and texture. We took nine samples from each of the 12 most common ESC's and incubated them at five temperatures (5-25°C), at four soil moisture levels (30-75% water holding capacity), and with an unfertilized and a fertilized treatment. So far, our results indicate that both soil respiration and the Q10 value are spatially highly variable with Q10 values ranging from 1 to 4. The Q10 value is altered by the level of soil moisture and decreases when soils are as moist as 75% water holding capacity. Fertilization has no effect on the Q10 value. Currently, we are processing the whole data-set to derive the effect of ESC's on the Q10 value. Recent data suggest that forest soils are more sensitive to warming than cropland soils.
Directory of Open Access Journals (Sweden)
Karn Wijarnpreecha
Full Text Available Iron-overload cardiomyopathy is a major cause of death in thalassemia patients due to the lack of an early detection strategy. Although cardiac magnetic resonance (CMR T2* is used for early detection of cardiac iron accumulation, its availability is limited. Heart rate variability (HRV has been used to evaluate cardiac autonomic function and found to be depressed in thalassemia. However, its direct correlation with cardiac iron accumulation has never been investigated. We investigated whether HRV can be used as an alternative indicator for early identification of cardiac iron deposition in thalassemia patients.Ninety-nine non-transfusion dependent thalassemia patients (23.00 (17.00, 32.75 years, 35 male were enrolled. The correlation between HRV recorded using 24-hour Holter monitoring and non-transferrin bound iron (NTBI, hemoglobin (Hb, serum ferritin, LV ejection fraction (LVEF, and CMR-T2* were determined.The median NTBI value was 3.15 (1.11, 6.59 μM. Both time and frequency domains of HRV showed a significant correlation with the NTBI level, supporting HRV as a marker of iron overload. Moreover, the LF/HF ratio showed a significant correlation with CMR-T2* with the receiver operating characteristic (ROC curve of 0.684±0.063, suggesting that it could represent the cardiac iron deposit in thalassemia patients. HRV was also significantly correlated with serum ferritin and Hb.This novel finding regarding the correlation between HRV and CMR-T2* indicates that HRV could be a potential marker in identifying early cardiac iron deposition prior to the development of LV dysfunction, and may be used as an alternative to CMR-T2* for screening cardiac iron status in thalassemia patients.
DEFF Research Database (Denmark)
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...
Indian Academy of Sciences (India)
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.
Azam, Muhammad Abid; Katz, Joel; Fashler, Samantha R; Changoor, Tina; Azargive, Saam; Ritvo, Paul
2015-10-01
Heart rate variability (HRV) is a vagal nerve-mediated biomarker of cardiac function used to investigate chronic illness, psychopathology, stress and, more recently, attention-regulation processes such as meditation. This study investigated HRV in relation to maladaptive perfectionism, a stress-related personality factor, and mindfulness meditation, a stress coping practice expected to elevate HRV, and thereby promote relaxation. Maladaptive perfectionists (n=21) and Controls (n=39) were exposed to a lab-based assessment in which HRV was measured during (1) a 5-minute baseline resting phase, (2) a 5-minute cognitive stress-induction phase, and (3) a post-stress phase. In the post-stress phase, participants were randomly assigned to a 10-minute audio-instructed mindfulness meditation condition or a 10-minute rest condition with audio-description of mindfulness meditation. Analyses revealed a significant elevation in HRV during meditation for Controls but not for Perfectionists. These results suggest that mindfulness meditation promotes relaxation following cognitive stress and that the perfectionist personality hinders relaxation possibly because of decreased cardiac vagal tone. The results are discussed in the context of developing psychophysiological models to advance therapeutic interventions for distressed populations. PMID:26116778
Directory of Open Access Journals (Sweden)
Milan Kubiatko
2014-11-01
Full Text Available Attitude is a dual-poled essence: possessing positive thoughts on a course or subject, liking a course or exhibiting positive affective nature in relation with it, or having negative thoughts on a course or subject, disliking it or exhibiting negative affective features in relation with it (Bloom, 1979. Attitudes are different from opinions, values and beliefs. Attitudes and opinions resemble each other, but they differ from attitudes in terms of degree of generalizability and the measuring technique. Opinions are personal reactions to specific occurrences and conditions. But attitudes should be taken in a more general sense, as they influence people's reactions against sets of events and groups of people, in a more broad sense. The teaching profession has been mentioned among the favorite occupations, and researchers wanted to know if attitudes have anything to do with this tendency. It has been a subject for many researches that attitudes towards teaching profession differ by gender (Cook & Medley, 1954; Capri & Celikkaleli, 2008; Cetin, 2003; Dogan & Coban, 2009. The aim of this research is to determine the impact of gender variable on the teaching profession via meta-analysis method. Effect models specified for meta-analysis have been compared. This research covers the results of meta-analysis combining 27 researches determined useful by master's theses and doctorate dissertations which take gender as the variable. Effect size of the gender in relation with the attitude towards the teaching profession is found to be 0.301 for the fixed effect model, and 0.304 for the random effect model. When a frequency table for directions of effect sizes is created, 20 researches (74% showed a positive effect size. Together with this result, 74% of the researches explain that females have more positive attitudes over males. Absence of any 0 effect size in this research explain that there has been no research indicating that attitudes towards the teaching
Wang, Sijian; Nan, Bin; Rosset, Saharon; Zhu, Ji
2011-03-01
We propose a computationally intensive method, the random lasso method, for variable selection in linear models. The method consists of two major steps. In step 1, the lasso method is applied to many bootstrap samples, each using a set of randomly selected covariates. A measure of importance is yielded from this step for each covariate. In step 2, a similar procedure to the first step is implemented with the exception that for each bootstrap sample, a subset of covariates is randomly selected with unequal selection probabilities determined by the covariates' importance. Adaptive lasso may be used in the second step with weights determined by the importance measures. The final set of covariates and their coefficients are determined by averaging bootstrap results obtained from step 2. The proposed method alleviates some of the limitations of lasso, elastic-net and related methods noted especially in the context of microarray data analysis: it tends to remove highly correlated variables altogether or select them all, and maintains maximal flexibility in estimating their coefficients, particularly with different signs; the number of selected variables is no longer limited by the sample size; and the resulting prediction accuracy is competitive or superior compared to the alternatives. We illustrate the proposed method by extensive simulation studies. The proposed method is also applied to a Glioblastoma microarray data analysis. PMID:22997542
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.
Uniform estimate for maximum of randomly weighted sums with applications to insurance risk theory
Institute of Scientific and Technical Information of China (English)
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.
van Goor, H; Stuiver, B
1998-01-01
Due to a lack of pertinent data, little is known about nonresponse in substantive, generally "dependent" variables and its consequences. However, in a study on policy performance of Dutch municipalities, we were fortunately able to gather performance data fur respondents and nonrespondents from inde
Directory of Open Access Journals (Sweden)
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
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
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.
Directory of Open Access Journals (Sweden)
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
Random effects coefficient of determination for mixed and meta-analysis models
Demidenko, Eugene; Sargent, James; Onega, Tracy
2012-01-01
The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, Rr2, that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If Rr2 is close to 0, t...
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.
History-Dependent Random Discounting
Higashi, Youichiro; Hyogo, Kazuya; Takeoka, Norio
2009-09-01
In the literature of dynamic models under uncertainty, it is commonly assumed that uncertainty is resolved gradually over time and its resolution is independent of the actions taken by a decision maker up to that time period. However, contingencies in the decision maker's mind may change and even increase over time according to habits that have evolved by experiences, actions, or consumptions in the past. We provide an axiomatic model where the decision maker faces uncertainty about her own time preference or discount factors in future and these uncertainty may evolve according to histories or habits from the past consumption.
Kissling, Grace E.; Dertinger, Stephen; Hayashi, Makoto; MacGregor, James T.
2007-01-01
Until recently, the in vivo erythrocyte micronucleus assay has been scored using microscopy. Because the frequency of micronucleated cells is typically low, cell counts are subject to substantial binomial counting error. Counting error, along with inter-animal variability, limit the sensitivity of this assay. Recently, flow cytometric methods have been developed for scoring micronucleated erythrocytes and these methods enable many more cells to be evaluated than is possible with microscopic s...
Institute of Scientific and Technical Information of China (English)
李思齐; 李昌兴; 柳晓燕
2011-01-01
二维连续型随机变量函数的密度函数的计算既是概率论教学中的一个重点,又是一个难点.本文介绍了一般二维连续型随机变量函数的分布密度的计算方法,并给出了一个新的方法——密度函数转化法.%Calculation of distribution density function of two-dimensional continuous random variable is one of the important and difficult points in probability theory teaching. The present paper first introduces some common methods for calculating the distribution density function of two-dimensional continuous random variable, and then a new approach--transform of density function is proposed.
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
Institute of Scientific and Technical Information of China (English)
谭成良; 吴群英; 何燕梅
2011-01-01
In this paper, we establish a Rosenthal-type inequality of partial sums for ρ--mixing random variables. As its applications, we get the complete convergence rates in the strong laws for ρ--mixing random variables. The result obtained extends the corresponding result.
Fritz, Robert L.
A study examined the association between field-dependence and its related information processing characteristics, and educational cognitive style as a model of conative influence. Data were collected from 145 secondary marketing education students in nothern Georgia during spring 1991. Descriptive statistics, Pearson product moment correlations,…
Savić R.; Petrović M.; Radojković D.; Radović Č.; Parunović N.; Pušić M.; Radišić R.
2013-01-01
The main objective of this study was to evaluate the effect of age (A) and the intensity of the boars' utilization (s) on the phenotypic variability of ejaculate volume (VOL) and sperm motility (MO). The study included 274 ejaculates of Large White boars (LW). Boars were divided into six classes according the age when the ejaculate was taken (10-13, 14-17, 18-21, 22-25, 26-29 and ≥30 months). Semen samples were analyzed during four seasons (spring, summer, ...
Institute of Scientific and Technical Information of China (English)
李金秋
2012-01-01
Considering the importance of uniform distribution and the higher-order moment of sum of random variables, the higher-order moment of sum of i. i. d U( 0,1) random variables is computed by multinomial theorem and Stirling number of the second kind in combinatorics. The computational formula is got Base on this formula and binomial theorem, the formula of the higher-moment of sum of i. i. d I/(a,b) random variables is got. At last, some examples are given.%考虑到均匀分布与随机变量和的高阶矩的重要性,利用组合数学中的多项式定理和第二类Stirling数对独立同U(0,1)随机变量和的高阶矩进行了计算,得到了相应的计算公式.并以此为基础利用二项式定理,得到了独立同U(a,b)随机变量和的高阶矩的计算公式.最后给出了计算实例.
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.
Michaelides, Michalis P.; Haertel, Edward H.
2014-01-01
The standard error of equating quantifies the variability in the estimation of an equating function. Because common items for deriving equated scores are treated as fixed, the only source of variability typically considered arises from the estimation of common-item parameters from responses of samples of examinees. Use of alternative, equally…
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.
El Hachimi, A. G.; Dakir, O.; Sidi Ahmed, S.; Zaari, H.; El Yadari, M.; Benyoussef, A.; El Kenz, A.
2016-09-01
The effect of random crystal-field on the stationary states of the kinetic spin-3/2 Blume-Capel model is investigated within the framework of the mean-field approach. The Glauber-type stochastic dynamics is used to describe the time evolution of the system which is subject to a time-dependent oscillating external magnetic field. In addition to the well-known phase transitions and the appearance of the partly ferromagnetic phase characterized by the magnetization m = 1 in equilibrium case, a new dynamical regions between the ferromagnetic phases F1/2, F1 and F3/2 are found where F3/2 +F 1 / 2 ,F3/2 +F1, F1 +F1/2 phases coexist for a weak value of the reduced magnetic field (h). Whereas for higher value of h both solutions ordered F and disordered P phases coexist. Hence we present six types topologies of phase diagrams which exhibit dynamical first-order, second-order transition lines, dynamical tricritical and isolated critical end points. Furthermore, the dynamical thermal behavior magnetizations, susceptibilities and phase space trajectories are given and discussed.
DEFF Research Database (Denmark)
Moeller, Niels C; Korsholm, Lars; Kristensen, Peter L;
2008-01-01
conditions had no apparent effect on inter-instrument variability. In all probability, the effect of technical calibration was primarily attenuated in the field by other more dominant sources of variation. However, routine technical assessments are still very important for determining the acceleration......BACKGROUND: Potentially, unit-specific in-vitro calibration of accelerometers could increase field data quality and study power. However, reduced inter-unit variability would only be important if random instrument variability contributes considerably to the total variation in field data. Therefore.......3% vs. CVcalibrated = 35.7%). High correlations (r = 0.99 & r = 0.98, respectively) were observed between raw and calibrated field data, and the proportion of the total variation caused by the MTI- and CSA monitor was estimated to be only 1.1% and 4.2%, respectively. Compared to the CSA instruments...
Directory of Open Access Journals (Sweden)
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.
Valenza, Gaetano; Nardelli, Mimma; Lanatà, Antonio; Gentili, Claudio; Bertschy, Gilles; Paradiso, Rita; Scilingo, Enzo Pasquale
2014-09-01
Current clinical practice in diagnosing patients affected by psychiatric disorders such as bipolar disorder is based only on verbal interviews and scores from specific questionnaires, and no reliable and objective psycho-physiological markers are taken into account. In this paper, we propose to use a wearable system based on a comfortable t-shirt with integrated fabric electrodes and sensors able to acquire electrocardiogram, respirogram, and body posture information in order to detect a pattern of objective physiological parameters to support diagnosis. Moreover, we implemented a novel ad hoc methodology of advanced biosignal processing able to effectively recognize four possible clinical mood states in bipolar patients (i.e., depression, mixed state, hypomania, and euthymia) continuously monitored up to 18 h, using heart rate variability information exclusively. Mood assessment is intended as an intrasubject evaluation in which the patient's states are modeled as a Markov chain, i.e., in the time domain, each mood state refers to the previous one. As validation, eight bipolar patients were monitored collecting and analyzing more than 400 h of autonomic and cardiovascular activity. Experimental results demonstrate that our novel concept of personalized and pervasive monitoring constitutes a viable and robust clinical decision support system for bipolar disorders recognizing mood states with a total classification accuracy up to 95.81%. PMID:24240031
Schein, ASO; Correa, APS; Casali, Karina Rabello; Schaan, Beatriz D.
2016-01-01
Background Physical exercise reduces glucose levels and glucose variability in patients with type 2 diabetes. Acute inspiratory muscle exercise has been shown to reduce these parameters in a small group of patients with type 2 diabetes, but these results have yet to be confirmed in a well-designed study. The aim of this study is to investigate the effect of acute inspiratory muscle exercise on glucose levels, glucose variability, and cardiovascular autonomic function in patients with type 2 d...
Park, Seong-Beom; Lee, Inah
2016-08-01
Place cells in the hippocampus fire at specific positions in space, and distal cues in the environment play critical roles in determining the spatial firing patterns of place cells. Many studies have shown that place fields are influenced by distal cues in foraging animals. However, it is largely unknown whether distal-cue-dependent changes in place fields appear in different ways in a memory task if distal cues bear direct significance to achieving goals. We investigated this possibility in this study. Rats were trained to choose different spatial positions in a radial arm in association with distal cue configurations formed by visual cue sets attached to movable curtains around the apparatus. The animals were initially trained to associate readily discernible distal cue configurations (0° vs. 80° angular separation between distal cue sets) with different food-well positions and then later experienced ambiguous cue configurations (14° and 66°) intermixed with the original cue configurations. Rats showed no difficulty in transferring the associated memory formed for the original cue configurations when similar cue configurations were presented. Place field positions remained at the same locations across different cue configurations, whereas stability and coherence of spatial firing patterns were significantly disrupted when ambiguous cue configurations were introduced. Furthermore, the spatial representation was extended backward and skewed more negatively at the population level when processing ambiguous cue configurations, compared with when processing the original cue configurations only. This effect was more salient for large cue-separation conditions than for small cue-separation conditions. No significant rate remapping was observed across distal cue configurations. These findings suggest that place cells in the hippocampus dynamically change their detailed firing characteristics in response to a modified cue environment and that some of the firing
Institute of Scientific and Technical Information of China (English)
王琳; 刘保东
2013-01-01
The random variable fuzzy recognition model was established for the coexistence of randomness and fuzziness in cleaner production assessment. A random term obeying normal distribution was introduced to the variable fuzzy recognition model, so the randomness and fuzziness could be studied simultaneously. Four random fuzzy recognition submodels were generated by controlling the distance parameter p and the optimization parameter a, and then according to the 3σ principle of normal distribution, after choosing a reasonable confidence, the grade was identified by the confidence interval of grade feature value. Compared with the scoring model of centesimal system, this model could cut down the effect of subjective preference on assessment results, and could improve the maneuverability and accuracy in evaluation process. The experimental results showed that the random variable fuzzy recognition model could evaluate the cleaner production level accurately, which could also provide a reference for cleaner production assessment.%针对清洁生产评价中模糊性与随机性并存的问题,建立随机可变模糊识别模型.向可变模糊识别模型中引入一个服从正态分布的随机项,同步研究模糊性和随机性.通过控制模型中距离参数p和优化准则参数α,得到4个随机模糊识别子模型,随后根据正态分布3σ原则,选择合理的置信度,得到级别特征值的置信区间,以此判断隶属级别.该模型与传统百分制评分模型相比削减了主观偏好对评价结果的影响,提高了评价的可操作性和准确性.实例结果证明随机可变模糊识别模型能准确评价清洁生产水平,为清洁生产评价工作提供参考.
Phase Transition in Unrestricted Random SAT
Schuh, Bernd R
2012-01-01
For random CNF formulae with m clauses, n variables and an unrestricted number of literals per clause the transition from high to low satisfiability can be determined exactly for large n. The critical density m/n turns out to be strongly n-dependent, ccr = ln(2)/(1-p)^^n, where pn is the mean number of positive literals per clause.This is in contrast to restricted random SAT problems (random K-SAT), where the critical ratio m/n is a constant. All transition lines are calculated by the second moment method applied to the number of solutions N of a formula. In contrast to random K-SAT, the method does not fail for the unrestricted model, because long range interactions between solutions are not cut off by disorder.
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 (pmeasurements 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 useful in differentiating CECS from other disorders or in predicting its response to either physical therapy or fasciotomy. PMID:24610770
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
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...
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 inseminations under lower SR values ( P inseminations during the summer were performed under significantly lower maximum T ( P inseminations resulted in pregnancy when they were carried out under higher maximum ( P 1 (maximum T, ET and rainfall on AI day, and ET and rainfall on day 15), and two variables presented OR <1 (SR on AI day and maximum T on day 15). However, the effect of meteorological factors affected fertility in opposite ways, so T becomes a protective or risk factor on fertility depending on season. In conclusion, the percentage of pregnancy after AI in sheep is significantly affected by meteorological variables in a seasonal-dependent manner, so the parameters such as temperature 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.
Complete Convergence of Series of Dependent Random Variables%相依随机变量序列的完全收敛性
Institute of Scientific and Technical Information of China (English)
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.
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.
Nishimura, Rimei; Tanaka, Yuko; Koiwai, Kazuki; Inoue, Kohei; Hach, Thomas; Salsali, Afshin; Lund, Søren S; Broedl, Uli C.
2015-01-01
Background This study evaluated the effect of empagliflozin on postprandial glucose (PPG) and 24-hour glucose variability in Japanese patients with type 2 diabetes mellitus (T2DM). Methods Patients (N = 60; baseline mean [SD] HbA1c 7.91 [0.80]%; body mass index 24.3 [3.2] kg/m2) were randomized to receive empagliflozin 10 mg (n = 20), empagliflozin 25 mg (n = 19) or placebo (n = 21) once daily as monotherapy for 28 days. A meal tolerance test and continuous glucose monitoring (CGM) for 24 hou...
Soichiro Kaneko; Masashi Watanabe; Shin Takayama; Takehiro Numata; Takashi Seki; Junichi Tanaka; Seiki Kanemura; Yutaka Kagaya; Tadashi Ishii; Yoshitaka Kimura; Nobuo Yaegashi
2013-01-01
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 mi...
Operational Risk Aggregation Based on Business Line Dependence: A Mutual Information Approach
Wenzhou Wang; Limeng Shi; Xiaoqian Zhu
2016-01-01
The dependencies between different business lines of banks have serious effects on the accuracy of operational risk estimation. Furthermore, the dependencies are far more complicated than simple linear correlation. While Pearson correlation coefficient is constructed based on the hypothesis of a linear association, the mutual information that measures all the information of a random variable contained in another random variable is a powerful alternative. Based on mutual information, the gener...
Institute of Scientific and Technical Information of China (English)
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
Directory of Open Access Journals (Sweden)
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.
Osborn, B.; Chapple, W.; Ewers, B. E.; Williams, D. G.
2014-12-01
The interaction between soil conditions and climate variability plays a central role in the ecohydrological functions of montane conifer forests. Although soil moisture availability to trees is largely dependent on climate, the depth and texture of soil exerts a key secondary influence. Multiple Pleistocene glacial events have shaped the landscape of the central Rocky Mountains creating a patchwork of soils differing in age and textural classification. This mosaic of soil conditions impacts hydrological properties, and montane conifer forests potentially respond to climate variability quite differently depending on the age of glacial till and soil development. We hypothesized that the age of glacial till and associated soil textural changes exert strong control on growth and photosynthetic gas exchange of lodgepole pine. We examined physiological and growth responses of lodgepole pine to interannual variation in maximum annual snow water equivalence (SWEmax) of montane snowpack and growing season air temperature (Tair) and vapor pressure deficit (VPD) across a chronosequence of Pleistocene glacial tills ranging in age from 700k to 12k years. Soil textural differences across the glacial tills illustrate the varying degrees of weathering with the most well developed soils with highest clay content on the oldest till surfaces. We show that sensitivity of growth and carbon isotope discrimination, an integrated measure of canopy gas exchange properties, to interannual variation SWEmax , Tair and VPD is greatest on young till surfaces, whereas trees on old glacial tills with well-developed soils are mostly insensitive to these interannual climate fluctuations. Tree-ring widths were most sensitive to changes in SWEmax on young glacial tills (p < 0.01), and less sensitive on the oldest till (p < 0.05). Tair correlates strongly with δ13C values on the oldest and youngest tills sites, but shows no significant relationship on the middle aged glacial till. It is clear that
Directory of Open Access Journals (Sweden)
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.
Energy Technology Data Exchange (ETDEWEB)
Cabout, T., E-mail: Thomas.Cabout@cea.fr [CEA LETI, MINATEC Campus, 17 Rue des Martyrs, 38054 Grenoble France (France); Buckley, J.; Cagli, C.; Jousseaume, V.; Nodin, J.-F.; Salvo, B. de [CEA LETI, MINATEC Campus, 17 Rue des Martyrs, 38054 Grenoble France (France); Bocquet, M.; Muller, Ch. [Im2np, UMR CNRS 7334, Aix-Marseille Université, 38 Rue Joliot Curie, 13451 Marseille Cedex 20 (France)
2013-04-30
This paper deals with the role of platinum or titanium–titanium nitride electrodes on variability of resistive switching characteristics and electrical performances of HfO{sub 2}-based memory elements. Capacitor-like Pt/HfO{sub 2} (10 nm)/Pt and Ti/HfO{sub 2} (10 nm)/TiN structures were fabricated on top of a tungsten pillar bottom electrode and integrated in-between two interconnect metal lines. First, quasi-static measurements were performed to apprehend the role of electrodes on electroforming, set and reset operations and their corresponding switching parameters. Memory elements with Pt as top and bottom electrodes exhibited a non-polar behavior with sharp decrease of current during reset operation while Ti/HfO{sub 2}/TiN capacitors showed a bipolar switching behavior, with a gradual reset. In a second step, statistical distributions of switching parameters (voltage and resistance) were extracted from data obtained on few hundreds of capacitors. Even if the resistance in low resistive state and reset voltage was found to be comparable for both types of electrodes, the progressive reset operation observed on samples with Ti/TiN electrodes led to a lower variability of resistance in high resistive state and concomitantly of set voltage. In addition Ti–TiN electrodes enabled gaining: (i) lower forming and set voltages with significantly narrower capacitor-to-capacitor distributions; (ii) a better data retention capability (10 years at 65 °C instead of 10 years at 50 °C for Pt electrodes); (iii) satisfactory dynamic performances with lower set and reset voltages for ramp speed ranging from 10{sup −2} to 10{sup 7} V/s. The significant improvement of switching behavior with Ti–TiN electrodes is mainly attributed to the formation of a native interface layer between HfO{sub 2} oxide and Ti top electrode. - Highlights: ► HfO2 based capacitor-like structures were fabricated with Pt and Ti based electrodes. ► Influence of electrode materials on switching
Some general random Taylor series
Institute of Scientific and Technical Information of China (English)
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.
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...
Tests of the random walk hypothesis for financial data
Nakamura, Tomomichi; Small, Michael
2007-04-01
We propose a method from the viewpoint of deterministic dynamical systems to investigate whether observed data follow a random walk (RW) and apply the method to several financial data. Our method is based on the previously proposed small-shuffle surrogate method. Hence, our method does not depend on the specific data distribution, although previously proposed methods depend on properties of the data distribution. The data we use are stock market (Standard & Poor's 500 in US market and Nikkei225 in Japanese market), exchange rate (British Pound/US dollar and Japanese Yen/US dollar), and commodity market (gold price and crude oil price). We found that these financial data are RW whose first differences are independently distributed random variables or time-varying random variables.
Cooper, Colin; Frieze, Alan
The aim of this article is to discuss some of the notions and applications of random walks on finite graphs, especially as they apply to random graphs. In this section we give some basic definitions, in Section 2 we review applications of random walks in computer science, and in Section 3 we focus on walks in random graphs.
Harvested populations are more variable only in more variable environments.
Cameron, Tom C; O'Sullivan, Daniel; Reynolds, Alan; Hicks, Joseph P; Piertney, Stuart B; Benton, Tim G
2016-06-01
The interaction between environmental variation and population dynamics is of major importance, particularly for managed and economically important species, and especially given contemporary changes in climate variability. Recent analyses of exploited animal populations contested whether exploitation or environmental variation has the greatest influence on the stability of population dynamics, with consequences for variation in yield and extinction risk. Theoretical studies however have shown that harvesting can increase or decrease population variability depending on environmental variation, and requested controlled empirical studies to test predictions. Here, we use an invertebrate model species in experimental microcosms to explore the interaction between selective harvesting and environmental variation in food availability in affecting the variability of stage-structured animal populations over 20 generations. In a constant food environment, harvesting adults had negligible impact on population variability or population size, but in the variable food environments, harvesting adults increased population variability and reduced its size. The impact of harvesting on population variability differed between proportional and threshold harvesting, between randomly and periodically varying environments, and at different points of the time series. Our study suggests that predicting the responses to selective harvesting is sensitive to the demographic structures and processes that emerge in environments with different patterns of environmental variation. PMID:27516873
Institute of Scientific and Technical Information of China (English)
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.
Institute of Scientific and Technical Information of China (English)
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.
Wrigge, Hermann; Zinserling, Jörg; Neumann, Peter; Muders, Thomas; Magnusson, Anders; Putensen, Christian; Hedenstierna, Göran
2005-01-01
Introduction Experimental and clinical studies have shown a reduction in intrapulmonary shunt with spontaneous breathing during airway pressure release ventilation (APRV) in acute lung injury. This reduction was related to reduced atelectasis and increased aeration. We hypothesized that spontaneous breathing will result in better ventilation and aeration of dependent lung areas and in less cyclic collapse during the tidal breath. Methods In this randomized controlled experimental trial, 22 pi...
International Nuclear Information System (INIS)
Random Amplified Polymorphic DNA (RAPDs) markers were utilized to detect polymorphism between pure lines and commercially available Basmati rice varieties to assess variation which may be helpful in quality control and varietal identification (Basmati-370 and derived radiation induced mutants), differentiation of mutants and parents, and identification of RAPD markers co-segregating with important agronomic traits including plant height, days to flower and grain quality. Basmati varieties were distinguished from non-Basmati varieties with the help of five diagnostic markers which will be useful for detecting mixing of non-Basmati and Basmati rices, currently a serious marketing problem. Different Basmati cultivars were identified with the help of diagnostic RAPD markers which can be used in quality control as well as for ''fingerprinting'' of cultivars. Different radiation induced mutants were also successfully distinguished from the parents on the basis of variety specific and mutant specific markers which will be useful for varietal identification. In addition to this, other markers were also identified which can differentiate mutants from each other and are being, used for the fingerprinting of different mutants, particularly the dwarf mutants having similar appearance but different parentage. For identification of RAPD markers co-segregating with plant height and days to flower, 50 F2 plants and four F3 families were studied from a reciprocal cross made between Kashmir Basmati (tall and early) and Basmati-198 (dwarf and late). Segregating bands were observed within these populations, and indicating the possible use of RAPD markers for tagging gene(s) of agronomic importance in rice. (author)
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.
Directory of Open Access Journals (Sweden)
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
Groeneveld, Marleen G.; Harriet J. Vermeer; van IJzendoorn, Marinus H.; Linting, Mariëlle
2016-01-01
Background The childcare environment offers a wide array of developmental opportunities for children. Providing children with a feeling of security to explore this environment is one of the most fundamental goals of childcare. Objective In the current study the effectiveness of Video-feedback Intervention to promote Positive Parenting-Child Care (VIPP-CC) was tested on children’s wellbeing in home-based childcare in a randomized controlled trial. Methods Forty-seven children and their caregiv...
Directory of Open Access Journals (Sweden)
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.
Kaneko, Soichiro; Watanabe, Masashi; Takayama, Shin; Numata, Takehiro; Seki, Takashi; Tanaka, Junichi; Kanemura, Seiki; Kagaya, Yutaka; Ishii, Tadashi; Kimura, Yoshitaka; Yaegashi, Nobuo
2013-01-01
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. PMID:24381632
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.
Salvucci, G.; Rigden, A. J.
2015-12-01
Daily time series of evapotranspiration and surface conductance to water vapor were estimated using the ETRHEQ method (Evapotranspiration from Relative Humidity at Equilibrium). ETRHEQ has been previously compared with ameriflux site-level measurements of ET at daily and seasonal time scales, with watershed water balance estimates, and with various benchmark ET data sets. The ETRHEQ method uses meteorological data collected at common weather stations and estimates the surface conductance by minimizing the vertical variance of the calculated relative humidity profile averaged over the day. The key advantage of the ETRHEQ method is that it does not require knowledge of the surface state (soil moisture, stomatal conductance, leaf are index, etc.) or site-specific calibration. The daily estimates of conductance from 229 weather stations for 53 years were analyzed for dependence on environmental variables known to impact stomatal conductance and soil diffusivity: surface temperature, surface vapor pressure deficit, solar radiation, antecedent precipitation (as a surrogate for soil moisture), and a seasonal vegetation greenness index. At each site the summertime (JJAS) conductance values estimated from ETRHEQ were fitted to a multiplicate Jarvis-type stress model. Functional dependence was not proscribed, but instead fitted using flexible piecewise-linear splines. The resulting stress functions reproduce the time series of conductance across a wide range of ecosystems and climates. The VPD stress term resembles that proposed by Oren (i.e., 1-m*log(VPD) ), with VPD measured in kilopascals. The equivalent value of m derived from our spline-fits at each station varied over a remarkably small range of 0.58 to 0.62, in agreement with Oren's original analysis based on leaf and tree-level measurements.
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
Institute of Scientific and Technical Information of China (English)
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.
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…
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.…
LENUS (Irish Health Repository)
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.
Energy Technology Data Exchange (ETDEWEB)
Asvany, O.; Savic, I.; Schlemmer, S.; Gerlich, D
2004-03-08
Reactions of methane cations, CH{sub 4}{sup +}, with H{sub 2}, HD and D{sub 2} have been studied in a variable temperature 22-pole ion trap from room temperature down to 15 K. The formation of CH{sub 5}{sup +} in collisions with H{sub 2} is slow at 300 K, but it becomes faster by at least one order of magnitude when the temperature is lowered to 15 K. This behavior is tentatively explained with a longer complex lifetime at low temperatures. However, since tunneling is most probably not responsible for product formation, other dynamical or statistical restrictions must be responsible for the negative temperature dependence. In collisions of CH{sub 4}{sup +} with HD, the CH{sub 5}{sup +} product ion (68% at 15 K) prevails over CH{sub 4}D{sup +} (32%). Reaction of CH{sub 4}{sup +} with D{sub 2} is found to be much slower than with H{sub 2} or HD. The rate coefficient for converting CH{sub 4}{sup +} into CH{sub 3}D{sup +} by H-D exchange has been determined to be smaller than 10{sup -12} cm{sup 3}/s, indicating that scrambling in the CH{sub 6}{sup +} complex is very unlikely.
LENUS (Irish Health Repository)
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.
Miller, Joseph S.; Rute, Jason
2015-01-01
Energy randomness is a notion of partial randomness introduced by Diamondstone and Kjos-Hanssen to characterize the sequences that can be elements of a Martin-L\\"of random closed set (in the sense of Barmpalias, Brodhead, Cenzer, Dashti, and Weber). It has also been applied by Allen, Bienvenu, and Slaman to the characterization of the possible zero times of a Martin-L\\"of random Brownian motion. In this paper, we show that $X \\in 2^\\omega$ is $s$-energy random if and only if $\\sum_{n\\in\\omega...
Directory of Open Access Journals (Sweden)
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
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.
Exponential-family Random Network Models
Fellows, I; Handcock, MS
2012-01-01
Random graphs, where the connections between nodes are considered random variables, have wide applicability in the social sciences. Exponential-family Random Graph Models (ERGM) have shown themselves to be a useful class of models for representing com- plex social phenomena. We generalize ERGM by also modeling nodal attributes as random variates, thus creating a random model of the full network, which we call Exponential-family Random Network Models (ERNM). We demonstrate how this framework a...
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.
Directory of Open Access Journals (Sweden)
Ho Chiang-Hong
2011-02-01
Full Text Available Abstract Background Hyperphosphatemia in patients with chronic kidney disease (CKD contributes to secondary hyperparathyroidism, soft tissue calcification, and increased mortality risk. This trial was conducted to examine the efficacy and safety of calcium acetate in controlling serum phosphorus in pre-dialysis patients with CKD. Methods In this randomized, double-blind, placebo-controlled trial, 110 nondialyzed patients from 34 sites with estimated GFR 2 and serum phosphorus > 4.5 mg/dL were randomized to calcium acetate or placebo for 12 weeks. The dose of study drugs was titrated to achieve target serum phosphorus of 2.7-4.5 mg/dL. Serum phosphorus, calcium, iPTH, bicarbonate and serum albumin were measured at baseline and every 2 weeks for the 12 week study period. The primary efficacy endpoint was serum phosphorus at 12 weeks. Secondary endpoints were to measure serum calcium and intact parathyroid hormone (iPTH levels. Results At 12 weeks, serum phosphorus concentration was significantly lower in the calcium acetate group compared to the placebo group (4.4 ± 1.2 mg/dL vs. 5.1 ± 1.4 mg/dL; p = 0.04. The albumin-adjusted serum calcium concentration was significantly higher (9.5 ± 0.8 vs. 8.8 ± 0.8; p p Conclusions In CKD patients not yet on dialysis, calcium acetate was effective in reducing serum phosphorus and iPTH over a 12 week period. Trial Registration www.clinicaltrials.gov NCT00211978.
Random fixed point theorems on product spaces
Ismat Beg; Naseer Shahzad
1993-01-01
The existence of random fixed point of a locally contractive random operator in first variable on product spaces is proved. The concept continuous random height-selection is discussed. Some random fixed point theorems for nonexpansive self and nonself maps are also obtained in product spaces.
Romano, Gerardo; Balasco, Marianna; Lapenna, Vincenzo; Siniscalchi, Agata; Telesca, Luciano; Tripaldi, Simona
2014-06-01
Since 2007, a permanent magnetotelluric (MT) monitoring station has been working in the seismic area of the Agri Valley (Basilicata region, southern Italy) in order to investigate the stability of the MT transfer function. The station was installed in a rural area near the supposed seismogenic fault of the strong earthquake (Mw = 6.9) that struck the Agri Valley in 1857. Analysing about 4 yr of MT data characterized by a low seismic activity, the long-term systematic variations of robust single station MT transfer function estimates were observed in two different sounding period ranges. First, a significant seasonal component of variability for short periods was noted; these short periods were up to 16 s and were linked to variations in wetting/drying of soil moisture in the shallower layers. Second, a connection between the monitored estimates and global geomagnetic activity, Ap index, was found, particularly in the [20-100 s] period range. Analysing remote reference results and tipper estimates in shorter monitoring window, it was shown that such effect cannot be explained by a local or incoherent noise, and a large-scale coherent source should be claimed. We show that this effect is subtle because it produces smooth estimates, satisfying the dispersion relationship between apparent resistivity and phase, with small error bars. As the global geomagnetic activity level increases, robust estimators, like the median value, can be considered as a representative of the estimates due to the natural source, and they tend to stabilize when the Ap index approaches 10. It is also worth noting that our monitored time window includes the recent global minimum of solar activity which occurred in 2009, thus enhancing the estimate dependence on the Ap index.
Random walkers versus random crowds: diffusion of large matrices
Gudowska-Nowak, Ewa; Janik, Romuald J.; Jurkiewicz, Jerzy; Nowak, Maciej A.; Wieczorek, Waldemar
2006-01-01
We briefly review the random matrix theory for large N by N matrices viewed as free random variables in a context of stochastic diffusion. We establish a surprising link between the spectral properties of matrix-valued multiplicative diffusion processes for hermitian and unitary ensembles.
International Nuclear Information System (INIS)
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 multicenter trial. This was a controlled, prospective, two-arm phase III-multicenter trial. The standard arm consisted of single fractions of 1.0 Gy applied two times a week, for a total dose of 6.0 Gy (total therapy time: 3 weeks). The experimental arm consisted of single fractions of 0.5 Gy applied 3 times a week, for a total dose of 6.0 Gy (total therapy time: 4 weeks). Following a statistical power calculation, there were 120 patients for each investigation arm. The main inclusion criteria were: age > = 40 years, clinical and radiologically diagnosed painful heel spur (plantar fasciitis), and current symptoms for at least 6 months. The main exclusion criteria were: former local trauma, surgery or radiotherapy of the heel; pregnant or breastfeeding women; and a pre-existing severe psychiatric or psychosomatic disorder. After approving a written informed consent the patients are randomized by a statistician into one of the trial arms. After radiotherapy, the patients are seen after six weeks, after twelve weeks and then every twelve weeks up to 48 weeks. Additionally, they receive a questionnaire every six weeks after the follow-up examinations up to 48 weeks. The effect is measured using the visual analogue scale of pain (VAS), the calcaneodynia score according to Rowe and the SF-12 score. The primary endpoint is the pain relief three months after therapy. Patients of both therapy arms with an insufficient result are offered a second radiotherapy series applying the standard dose
Institute of Scientific and Technical Information of China (English)
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
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.
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 (<7 mW) was observed. The attainment of higher nonlinear current-voltage (I-V) characteristics in terms of the step-by-step reset 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. PMID:27518231
Directory of Open Access Journals (Sweden)
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.
Coupled continuous time random walks in finance
Meerschaert, M M; Meerschaert, Mark M.; Scalas, Enrico
2006-01-01
Continuous time random walks (CTRWs) are used in physics to model anomalous diffusion, by incorporating a random waiting time between particle jumps. In finance, the particle jumps are log-returns and the waiting times measure delay between transactions. These two random variables (log-return and waiting time) are typically not independent. For these coupled CTRW models, we can now compute the limiting stochastic process (just like Brownian motion is the limit of a simple random walk), even in the case of heavy tailed (power-law) price jumps and/or waiting times. The probability density functions for this limit process solve fractional partial differential equations. In some cases, these equations can be explicitly solved to yield descriptions of long-term price changes, based on a high-resolution model of individual trades that includes the statistical dependence between waiting times and the subsequent log-returns. In the heavy tailed case, this involves operator stable space-time random vectors that genera...
Institute of Scientific and Technical Information of China (English)
马军杰; 柯华; 马卫民
2013-01-01
对于实际工程的管理者和决策者来说,工程整体费用和工期之间如何达到均衡以及工程所处环境的不确定性是两个必须要面对和考虑的问题.基于相关机会规划的思想,针对随机性和模糊性并存的复杂不确定环境,提出了一类时间费用均衡模型.在建立的模型中,以模糊随机变量来刻画工程所处的复杂不确定环境.随后,结合模糊随机模拟方法和遗传算法设计了一种混合智能算法,用于求解该模型.最后,通过数值实验来验证所设计算法的有效性和稳定性.%In real projects, the trade-off between the project cost and the completion time, and the uncertainty of the environment are both considerable aspects for managers. Due to the complex uncertain environment with coexisted randomness and fuzziness, a type of time-cost trade-off model based on the philosophy of dependent-chance programming is presented. In the proposed model, the environmental uncertainty of the project is described via fuzzy random variable. A searching method integrating the technique of fuzzy random simulation and genetic algorithm is designed to search the quasi-optimal schedule under some decision-making criterion. A numerical example is given to demonstrate the feasibility of the searching method for solving the proposed model.
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
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.
Institute of Scientific and Technical Information of China (English)
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.
Janssens, Lizanne; Stoks, Robby
2013-01-01
Interactions between pollutants and suboptimal environmental conditions can have severe consequences for the toxicity of pollutants, yet are still poorly understood. To identify patterns across environmental conditions and across fitness-related variables we exposed Enallagma cyathigerum damselfly larvae to the pesticide chlorpyrifos at two food levels or at two temperatures and quantified four fitness-related variables (larval survival, development time, mass at emergence and adult cold resi...
Josephine, Faass; Michael, Lahr
2007-01-01
This paper is an investigation into the relative importance of a wide variety of factors in influencing whether members of the American public support or oppose the use of biotechnology in agriculture and food production. To accomplish this end, as well as to facilitate the examination of a large number of independent variables simultaneously, several statistical methods, including factor analyses, instrumental variables analysis, and probit and logistic regressions were performed. It was d...
Random effects coefficient of determination for mixed and meta-analysis models.
Demidenko, Eugene; Sargent, James; Onega, Tracy
2012-01-01
The key feature of a mixed model is the presence of random effects. We have developed a coefficient, called the random effects coefficient of determination, [Formula: see text], that estimates the proportion of the conditional variance of the dependent variable explained by random effects. This coefficient takes values from 0 to 1 and indicates how strong the random effects are. The difference from the earlier suggested fixed effects coefficient of determination is emphasized. If [Formula: see text] is close to 0, there is weak support for random effects in the model because the reduction of the variance of the dependent variable due to random effects is small; consequently, random effects may be ignored and the model simplifies to standard linear regression. The value of [Formula: see text] apart from 0 indicates the evidence of the variance reduction in support of the mixed model. If random effects coefficient of determination is close to 1 the variance of random effects is very large and random effects turn into free fixed effects-the model can be estimated using the dummy variable approach. We derive explicit formulas for [Formula: see text] in three special cases: the random intercept model, the growth curve model, and meta-analysis model. Theoretical results are illustrated with three mixed model examples: (1) travel time to the nearest cancer center for women with breast cancer in the U.S., (2) cumulative time watching alcohol related scenes in movies among young U.S. teens, as a risk factor for early drinking onset, and (3) the classic example of the meta-analysis model for combination of 13 studies on tuberculosis vaccine. PMID:23750070
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.