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Sample records for bivariate association tests

  1. Family-based bivariate association tests for quantitative traits.

    Directory of Open Access Journals (Sweden)

    Lei Zhang

    Full Text Available The availability of a large number of dense SNPs, high-throughput genotyping and computation methods promotes the application of family-based association tests. While most of the current family-based analyses focus only on individual traits, joint analyses of correlated traits can extract more information and potentially improve the statistical power. However, current TDT-based methods are low-powered. Here, we develop a method for tests of association for bivariate quantitative traits in families. In particular, we correct for population stratification by the use of an integration of principal component analysis and TDT. A score test statistic in the variance-components model is proposed. Extensive simulation studies indicate that the proposed method not only outperforms approaches limited to individual traits when pleiotropic effect is present, but also surpasses the power of two popular bivariate association tests termed FBAT-GEE and FBAT-PC, respectively, while correcting for population stratification. When applied to the GAW16 datasets, the proposed method successfully identifies at the genome-wide level the two SNPs that present pleiotropic effects to HDL and TG traits.

  2. Statistical Test for Bivariate Uniformity

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    Zhenmin Chen

    2014-01-01

    Full Text Available The purpose of the multidimension uniformity test is to check whether the underlying probability distribution of a multidimensional population differs from the multidimensional uniform distribution. The multidimensional uniformity test has applications in various fields such as biology, astronomy, and computer science. Such a test, however, has received less attention in the literature compared with the univariate case. A new test statistic for checking multidimensional uniformity is proposed in this paper. Some important properties of the proposed test statistic are discussed. As a special case, the bivariate statistic test is discussed in detail in this paper. The Monte Carlo simulation is used to compare the power of the newly proposed test with the distance-to-boundary test, which is a recently published statistical test for multidimensional uniformity. It has been shown that the test proposed in this paper is more powerful than the distance-to-boundary test in some cases.

  3. Cumulative Incidence Association Models for Bivariate Competing Risks Data.

    Science.gov (United States)

    Cheng, Yu; Fine, Jason P

    2012-03-01

    Association models, like frailty and copula models, are frequently used to analyze clustered survival data and evaluate within-cluster associations. The assumption of noninformative censoring is commonly applied to these models, though it may not be true in many situations. In this paper, we consider bivariate competing risk data and focus on association models specified for the bivariate cumulative incidence function (CIF), a nonparametrically identifiable quantity. Copula models are proposed which relate the bivariate CIF to its corresponding univariate CIFs, similarly to independently right censored data, and accommodate frailty models for the bivariate CIF. Two estimating equations are developed to estimate the association parameter, permitting the univariate CIFs to be estimated either parametrically or nonparametrically. Goodness-of-fit tests are presented for formally evaluating the parametric models. Both estimators perform well with moderate sample sizes in simulation studies. The practical use of the methodology is illustrated in an analysis of dementia associations.

  4. The relative performance of bivariate causality tests in small samples

    NARCIS (Netherlands)

    Bult, J..R.; Leeflang, P.S.H.; Wittink, D.R.

    1997-01-01

    Causality tests have been applied to establish directional effects and to reduce the set of potential predictors, For the latter type of application only bivariate tests can be used, In this study we compare bivariate causality tests. Although the problem addressed is general and could benefit resea

  5. Multivariate Longitudinal Analysis with Bivariate Correlation Test

    Science.gov (United States)

    Adjakossa, Eric Houngla; Sadissou, Ibrahim; Hounkonnou, Mahouton Norbert; Nuel, Gregory

    2016-01-01

    In the context of multivariate multilevel data analysis, this paper focuses on the multivariate linear mixed-effects model, including all the correlations between the random effects when the dimensional residual terms are assumed uncorrelated. Using the EM algorithm, we suggest more general expressions of the model’s parameters estimators. These estimators can be used in the framework of the multivariate longitudinal data analysis as well as in the more general context of the analysis of multivariate multilevel data. By using a likelihood ratio test, we test the significance of the correlations between the random effects of two dependent variables of the model, in order to investigate whether or not it is useful to model these dependent variables jointly. Simulation studies are done to assess both the parameter recovery performance of the EM estimators and the power of the test. Using two empirical data sets which are of longitudinal multivariate type and multivariate multilevel type, respectively, the usefulness of the test is illustrated. PMID:27537692

  6. Joint association analysis of bivariate quantitative and qualitative traits.

    Science.gov (United States)

    Yuan, Mengdie; Diao, Guoqing

    2011-11-29

    Univariate genome-wide association analysis of quantitative and qualitative traits has been investigated extensively in the literature. In the presence of correlated phenotypes, it is more intuitive to analyze all phenotypes simultaneously. We describe an efficient likelihood-based approach for the joint association analysis of quantitative and qualitative traits in unrelated individuals. We assume a probit model for the qualitative trait, under which an unobserved latent variable and a prespecified threshold determine the value of the qualitative trait. To jointly model the quantitative and qualitative traits, we assume that the quantitative trait and the latent variable follow a bivariate normal distribution. The latent variable is allowed to be correlated with the quantitative phenotype. Simultaneous modeling of the quantitative and qualitative traits allows us to make more precise inference on the pleiotropic genetic effects. We derive likelihood ratio tests for the testing of genetic effects. An application to the Genetic Analysis Workshop 17 data is provided. The new method yields reasonable power and meaningful results for the joint association analysis of the quantitative trait Q1 and the qualitative trait disease status at SNPs with not too small MAF.

  7. Modified likelihood ratio test for homogeneity in bivariate normal mixtures with presence of a structural parameter

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    This paper investigates the asymptotic properties of the modified likelihood ratio statistic for testing homogeneity in bivariate normal mixture models with an unknown structural parameter. It is shown that the modified likelihood ratio statistic has χ22 null limiting distribution.

  8. A simple powerful bivariate test for two sample location problems in experimental and observational studies

    OpenAIRE

    2010-01-01

    Abstract Background In many areas of medical research, a bivariate analysis is desirable because it simultaneously tests two response variables that are of equal interest and importance in two populations. Several parametric and nonparametric bivariate procedures are available for the location problem but each of them requires a series of stringent assumptions such as specific distribution, affine-invariance or elliptical symmetry. The aim of this study is to propose a powerful test statistic...

  9. A simple powerful bivariate test for two sample location problems in experimental and observational studies

    Directory of Open Access Journals (Sweden)

    Ayatollahi S MT

    2010-05-01

    Full Text Available Abstract Background In many areas of medical research, a bivariate analysis is desirable because it simultaneously tests two response variables that are of equal interest and importance in two populations. Several parametric and nonparametric bivariate procedures are available for the location problem but each of them requires a series of stringent assumptions such as specific distribution, affine-invariance or elliptical symmetry. The aim of this study is to propose a powerful test statistic that requires none of the aforementioned assumptions. We have reduced the bivariate problem to the univariate problem of sum or subtraction of measurements. A simple bivariate test for the difference in location between two populations is proposed. Method In this study the proposed test is compared with Hotelling's T2 test, two sample Rank test, Cramer test for multivariate two sample problem and Mathur's test using Monte Carlo simulation techniques. The power study shows that the proposed test performs better than any of its competitors for most of the populations considered and is equivalent to the Rank test in specific distributions. Conclusions Using simulation studies, we show that the proposed test will perform much better under different conditions of underlying population distribution such as normality or non-normality, skewed or symmetric, medium tailed or heavy tailed. The test is therefore recommended for practical applications because it is more powerful than any of the alternatives compared in this paper for almost all the shifts in location and in any direction.

  10. A MODIFIED LIKELIHOOD RATIO TEST FOR HOMOGENEITY IN BIVARIATE NORMAL MIXTURES OF TWO SAMPLES

    Institute of Scientific and Technical Information of China (English)

    Qingzhu LEI; Yongsong QIN

    2009-01-01

    This paper investigates the asymptotic properties of a modified likelihood ratio statistic for testing homogeneity in bivariate normal mixture models of two samples. The asymptotic null distribution of the modified likelihood ratio statistic is found to be X~2_2, where X~2_2 is a chi-squared distribution with 2 degrees of freedom.

  11. Two-Sample, Bivariate Hypothesis Testing Methods Based on Tukey's Depth.

    Science.gov (United States)

    Wilcox, Rand R.

    2003-01-01

    Conducted simulations to explore methods for comparing bivariate distributions corresponding to two independent groups, all of which are based on Tukey's "depth," a generalization of the notion of ranks to multivariate data. Discusses steps needed to control Type I error. (SLD)

  12. Bivariate genome-wide association study suggests that the DARC gene influences lean body mass and age at menarche.

    Science.gov (United States)

    Hai, Rong; Zhang, Lei; Pei, Yufang; Zhao, Lanjuan; Ran, Shu; Han, Yingying; Zhu, Xuezhen; Shen, Hui; Tian, Qing; Deng, Hongwen

    2012-06-01

    Lean body mass (LBM) and age at menarche (AAM) are two important complex traits for human health. The aim of this study was to identify pleiotropic genes for both traits using a powerful bivariate genome-wide association study (GWAS). Two studies, a discovery study and a replication study, were performed. In the discovery study, 909622 single nucleotide polymorphisms (SNPs) were genotyped in 801 unrelated female Han Chinese subjects using the Affymetrix human genome-wide SNP array 6.0 platform. Then, a bivariate GWAS was performed to identify the SNPs that may be important for LBM and AAM. In the replication study, significant findings from the discovery study were validated in 1692 unrelated Caucasian female subjects. One SNP rs3027009 that was bivariately associated with left arm lean mass and AAM in the discovery samples (P=7.26×10(-6)) and in the replication samples (P=0.005) was identified. The SNP is located at the upstream of DARC (Duffy antigen receptor for chemokines) gene, suggesting that DARC may play an important role in regulating the metabolisms of both LBM and AAM.

  13. A mixed effect model for bivariate meta-analysis of diagnostic test accuracy studies using a copula representation of the random effects distribution.

    Science.gov (United States)

    Nikoloulopoulos, Aristidis K

    2015-12-20

    Diagnostic test accuracy studies typically report the number of true positives, false positives, true negatives and false negatives. There usually exists a negative association between the number of true positives and true negatives, because studies that adopt less stringent criterion for declaring a test positive invoke higher sensitivities and lower specificities. A generalized linear mixed model (GLMM) is currently recommended to synthesize diagnostic test accuracy studies. We propose a copula mixed model for bivariate meta-analysis of diagnostic test accuracy studies. Our general model includes the GLMM as a special case and can also operate on the original scale of sensitivity and specificity. Summary receiver operating characteristic curves are deduced for the proposed model through quantile regression techniques and different characterizations of the bivariate random effects distribution. Our general methodology is demonstrated with an extensive simulation study and illustrated by re-analysing the data of two published meta-analyses. Our study suggests that there can be an improvement on GLMM in fit to data and makes the argument for moving to copula random effects models. Our modelling framework is implemented in the package CopulaREMADA within the open source statistical environment R.

  14. Powerful bivariate genome-wide association analyses suggest the SOX6 gene influencing both obesity and osteoporosis phenotypes in males.

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    Yao-Zhong Liu

    Full Text Available BACKGROUND: Current genome-wide association studies (GWAS are normally implemented in a univariate framework and analyze different phenotypes in isolation. This univariate approach ignores the potential genetic correlation between important disease traits. Hence this approach is difficult to detect pleiotropic genes, which may exist for obesity and osteoporosis, two common diseases of major public health importance that are closely correlated genetically. PRINCIPAL FINDINGS: To identify such pleiotropic genes and the key mechanistic links between the two diseases, we here performed the first bivariate GWAS of obesity and osteoporosis. We searched for genes underlying co-variation of the obesity phenotype, body mass index (BMI, with the osteoporosis risk phenotype, hip bone mineral density (BMD, scanning approximately 380,000 SNPs in 1,000 unrelated homogeneous Caucasians, including 499 males and 501 females. We identified in the male subjects two SNPs in intron 1 of the SOX6 (SRY-box 6 gene, rs297325 and rs4756846, which were bivariately associated with both BMI and hip BMD, achieving p values of 6.82x10(-7 and 1.47x10(-6, respectively. The two SNPs ranked at the top in significance for bivariate association with BMI and hip BMD in the male subjects among all the approximately 380,000 SNPs examined genome-wide. The two SNPs were replicated in a Framingham Heart Study (FHS cohort containing 3,355 Caucasians (1,370 males and 1,985 females from 975 families. In the FHS male subjects, the two SNPs achieved p values of 0.03 and 0.02, respectively, for bivariate association with BMI and femoral neck BMD. Interestingly, SOX6 was previously found to be essential to both cartilage formation/chondrogenesis and obesity-related insulin resistance, suggesting the gene's dual role in both bone and fat. CONCLUSIONS: Our findings, together with the prior biological evidence, suggest the SOX6 gene's importance in co-regulation of obesity and osteoporosis.

  15. Testing for a Common Volatility Process and Information Spillovers in Bivariate Financial Time Series Models

    NARCIS (Netherlands)

    J. Chen (Jinghui); M. Kobayashi (Masahito); M.J. McAleer (Michael)

    2016-01-01

    textabstractThe paper considers the problem as to whether financial returns have a common volatility process in the framework of stochastic volatility models that were suggested by Harvey et al. (1994). We propose a stochastic volatility version of the ARCH test proposed by Engle and Susmel (1993),

  16. Ordinal Bivariate Inequality

    DEFF Research Database (Denmark)

    Sonne-Schmidt, Christoffer Scavenius; Tarp, Finn; Østerdal, Lars Peter Raahave

    2016-01-01

    This paper introduces a concept of inequality comparisons with ordinal bivariate categorical data. In our model, one population is more unequal than another when they have common arithmetic median outcomes and the first can be obtained from the second by correlation-increasing switches and...

  17. A new bivariate negative binomial regression model

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    Faroughi, Pouya; Ismail, Noriszura

    2014-12-01

    This paper introduces a new form of bivariate negative binomial (BNB-1) regression which can be fitted to bivariate and correlated count data with covariates. The BNB regression discussed in this study can be fitted to bivariate and overdispersed count data with positive, zero or negative correlations. The joint p.m.f. of the BNB1 distribution is derived from the product of two negative binomial marginals with a multiplicative factor parameter. Several testing methods were used to check overdispersion and goodness-of-fit of the model. Application of BNB-1 regression is illustrated on Malaysian motor insurance dataset. The results indicated that BNB-1 regression has better fit than bivariate Poisson and BNB-2 models with regards to Akaike information criterion.

  18. Sequential Temporal Dependencies in Associations between Symptoms of Depression and Posttraumatic Stress Disorder: An Application of Bivariate Latent Difference Score Structural Equation Modeling

    Science.gov (United States)

    King, Daniel W.; King, Lynda A.; McArdle, John J.; Shalev, Arieh Y.; Doron-LaMarca, Susan

    2009-01-01

    Depression and posttraumatic stress disorder (PTSD) are highly comorbid conditions that may arise following exposure to psychological trauma. This study examined their temporal sequencing and mutual influence using bivariate latent difference score structural equation modeling. Longitudinal data from 182 emergency room patients revealed level of…

  19. Statistical Modeling of Bivariate Data.

    Science.gov (United States)

    1982-08-01

    end identify by lock nsum br) joint density-quantile function, dependence-density, non-parametric bivariate density estimation, entropy , exponential...estimated, by autoregressive or exponential model estimators I with maximum entropy properties, is investigated in this thesis. The results provide...important and useful procedures for nonparametric bivariate density estimation. The thesis discusses estimators of the entropy H(d) of ul2) which seem to me

  20. Covariate analysis of bivariate survival data

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, L.E.

    1992-01-01

    The methods developed are used to analyze the effects of covariates on bivariate survival data when censoring and ties are present. The proposed method provides models for bivariate survival data that include differential covariate effects and censored observations. The proposed models are based on an extension of the univariate Buckley-James estimators which replace censored data points by their expected values, conditional on the censoring time and the covariates. For the bivariate situation, it is necessary to determine the expectation of the failure times for one component conditional on the failure or censoring time of the other component. Two different methods have been developed to estimate these expectations. In the semiparametric approach these expectations are determined from a modification of Burke's estimate of the bivariate empirical survival function. In the parametric approach censored data points are also replaced by their conditional expected values where the expected values are determined from a specified parametric distribution. The model estimation will be based on the revised data set, comprised of uncensored components and expected values for the censored components. The variance-covariance matrix for the estimated covariate parameters has also been derived for both the semiparametric and parametric methods. Data from the Demographic and Health Survey was analyzed by these methods. The two outcome variables are post-partum amenorrhea and breastfeeding; education and parity were used as the covariates. Both the covariate parameter estimates and the variance-covariance estimates for the semiparametric and parametric models will be compared. In addition, a multivariate test statistic was used in the semiparametric model to examine contrasts. The significance of the statistic was determined from a bootstrap distribution of the test statistic.

  1. Bivariate correlation coefficients in family-type clustered studies.

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    Luo, Jingqin; D'Angela, Gina; Gao, Feng; Ding, Jimin; Xiong, Chengjie

    2015-11-01

    We propose a unified approach based on a bivariate linear mixed effects model to estimate three types of bivariate correlation coefficients (BCCs), as well as the associated variances between two quantitative variables in cross-sectional data from a family-type clustered design. These BCCs are defined at different levels of experimental units including clusters (e.g., families) and subjects within clusters and assess different aspects on the relationships between two variables. We study likelihood-based inferences for these BCCs, and provide easy implementation using standard software SAS. Unlike several existing BCC estimators in the literature on clustered data, our approach can seamlessly handle two major analytic challenges arising from a family-type clustered design: (1) many families may consist of only one single subject; (2) one of the paired measurements may be missing for some subjects. Hence, our approach maximizes the use of data from all subjects (even those missing one of the two variables to be correlated) from all families, regardless of family size. We also conduct extensive simulations to show that our estimators are superior to existing estimators in handling missing data or/and imbalanced family sizes and the proposed Wald test maintains good size and power for hypothesis testing. Finally, we analyze a real-world Alzheimer's disease dataset from a family clustered study to investigate the BCCs across different modalities of disease markers including cognitive tests, cerebrospinal fluid biomarkers, and neuroimaging biomarkers.

  2. Bivariate value-at-risk

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    Giuseppe Arbia

    2007-10-01

    Full Text Available In this paper we extend the concept of Value-at-risk (VaR to bivariate return distributions in order to obtain measures of the market risk of an asset taking into account additional features linked to downside risk exposure. We first present a general definition of risk as the probability of an adverse event over a random distribution and we then introduce a measure of market risk (b-VaR that admits the traditional b of an asset in portfolio management as a special case when asset returns are normally distributed. Empirical evidences are provided by using Italian stock market data.

  3. GLOBAL SMOOTHNESS PRESERVATION BY BIVARIATE INTERPOLATION OPERATORS

    Institute of Scientific and Technical Information of China (English)

    S.G.Gal; J.Szabados

    2003-01-01

    Extending the results of [4] in the univariate case, in this paper we prove that the bivariate interpolation polynomials of Hermite-Fejer based on the Chebyshev nodes of the first kind, those of Lagrange based on the Chebyshev nodes of second kind and ± 1, and those of bivariate Shepard operators, have the property of partial preservation of global smoothness, with respect to various bivariate moduli of continuity.

  4. Incomplete Bivariate Fibonacci and Lucas -Polynomials

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    Dursun Tasci

    2012-01-01

    Full Text Available We define the incomplete bivariate Fibonacci and Lucas -polynomials. In the case =1, =1, we obtain the incomplete Fibonacci and Lucas -numbers. If =2, =1, we have the incomplete Pell and Pell-Lucas -numbers. On choosing =1, =2, we get the incomplete generalized Jacobsthal number and besides for =1 the incomplete generalized Jacobsthal-Lucas numbers. In the case =1, =1, =1, we have the incomplete Fibonacci and Lucas numbers. If =1, =1, =1, =⌊(−1/(+1⌋, we obtain the Fibonacci and Lucas numbers. Also generating function and properties of the incomplete bivariate Fibonacci and Lucas -polynomials are given.

  5. BIVARIATE FRACTAL INTERPOLATION FUNCTIONS ON RECTANGULAR DOMAINS

    Institute of Scientific and Technical Information of China (English)

    Xiao-yuan Qian

    2002-01-01

    Non-tensor product bivariate fractal interpolation functions defined on gridded rectangular domains are constructed. Linear spaces consisting of these functions are introduced.The relevant Lagrange interpolation problem is discussed. A negative result about the existence of affine fractal interpolation functions defined on such domains is obtained.

  6. BIVARIATE REAL-VALUED ORTHOGONAL PERIODIC WAVELETS

    Institute of Scientific and Technical Information of China (English)

    Qiang Li; Xuezhang Liang

    2005-01-01

    In this paper, we construct a kind of bivariate real-valued orthogonal periodic wavelets. The corresponding decomposition and reconstruction algorithms involve only 8 terms respectively which are very simple in practical computation. Moreover, the relation between periodic wavelets and Fourier series is also discussed.

  7. Bivariate phase-rectified signal averaging

    CERN Document Server

    Schumann, Aicko Y; Bauer, Axel; Schmidt, Georg

    2008-01-01

    Phase-Rectified Signal Averaging (PRSA) was shown to be a powerful tool for the study of quasi-periodic oscillations and nonlinear effects in non-stationary signals. Here we present a bivariate PRSA technique for the study of the inter-relationship between two simultaneous data recordings. Its performance is compared with traditional cross-correlation analysis, which, however, does not work well for non-stationary data and cannot distinguish the coupling directions in complex nonlinear situations. We show that bivariate PRSA allows the analysis of events in one signal at times where the other signal is in a certain phase or state; it is stable in the presence of noise and impassible to non-stationarities.

  8. Characterizations of some bivariate models using reciprocal coordinate subtangents

    OpenAIRE

    Sreenarayanapurath Madhavan Sunoj; Sreejith Thoppil Bhargavan; Jorge Navarro

    2014-01-01

    In the present paper, we consider the bivariate version of reciprocal coordinate subtangent (RCST) and study its usefulness in characterizing some important bivariate models.  In particular, characterization results are proved for a general bivariate model whose conditional distributions are proportional hazard rate models (see Navarro and Sarabia, 2011), Sarmanov family and Ali-Mikhail-Haq family of bivariate distributions.  We also study the relationship between local dependence function an...

  9. Characterizations of some bivariate models using reciprocal coordinate subtangents

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    Sreenarayanapurath Madhavan Sunoj

    2014-06-01

    Full Text Available In the present paper, we consider the bivariate version of reciprocal coordinate subtangent (RCST and study its usefulness in characterizing some important bivariate models.  In particular, characterization results are proved for a general bivariate model whose conditional distributions are proportional hazard rate models (see Navarro and Sarabia, 2011, Sarmanov family and Ali-Mikhail-Haq family of bivariate distributions.  We also study the relationship between local dependence function and reciprocal subtangent and a characterization result is proved for a bivariate model proposed by Jones (1998.  Further, the concept of reciprocal coordinate subtangent is extended to conditionally specified models.

  10. Spectral density regression for bivariate extremes

    KAUST Repository

    Castro Camilo, Daniela

    2016-05-11

    We introduce a density regression model for the spectral density of a bivariate extreme value distribution, that allows us to assess how extremal dependence can change over a covariate. Inference is performed through a double kernel estimator, which can be seen as an extension of the Nadaraya–Watson estimator where the usual scalar responses are replaced by mean constrained densities on the unit interval. Numerical experiments with the methods illustrate their resilience in a variety of contexts of practical interest. An extreme temperature dataset is used to illustrate our methods. © 2016 Springer-Verlag Berlin Heidelberg

  11. A bivariate chromatic polynomial for signed graphs

    CERN Document Server

    Beck, Matthias

    2012-01-01

    We study Dohmen--P\\"onitz--Tittmann's bivariate chromatic polynomial $c_\\Gamma(k,l)$ which counts all $(k+l)$-colorings of a graph $\\Gamma$ such that adjacent vertices get different colors if they are $\\le k$. Our first contribution is an extension of $c_\\Gamma(k,l)$ to signed graphs, for which we obtain an inclusion--exclusion formula and several special evaluations giving rise, e.g., to polynomials that encode balanced subgraphs. Our second goal is to derive combinatorial reciprocity theorems for $c_\\Gamma(k,l)$ and its signed-graph analogues, reminiscent of Stanley's reciprocity theorem linking chromatic polynomials to acyclic orientations.

  12. The structure of bivariate rational hypergeometric functions

    CERN Document Server

    Cattani, Eduardo; Villegas, Fernando Rodriguez

    2009-01-01

    We describe the structure of all codimension-two lattice configurations $A$ which admit a stable rational $A$-hypergeometric function, that is a rational function $F$ all whose partial derivatives are non zero, and which is a solution of the $A$-hypergeometric system of partial differential equations defined by Gel'fand, Kapranov and Zelevinsky. We show, moreover, that all stable rational $A$-hypergeometric functions may be described by toric residues and apply our results to study the rationality of bivariate series whose coefficients are quotients of factorials of linear forms.

  13. APPROXIMATE SAMPLING THEOREM FOR BIVARIATE CONTINUOUS FUNCTION

    Institute of Scientific and Technical Information of China (English)

    杨守志; 程正兴; 唐远炎

    2003-01-01

    An approximate solution of the refinement equation was given by its mask, and the approximate sampling theorem for bivariate continuous function was proved by applying the approximate solution. The approximate sampling function defined uniquely by the mask of the refinement equation is the approximate solution of the equation, a piece-wise linear function, and posseses an explicit computation formula. Therefore the mask of the refinement equation is selected according to one' s requirement, so that one may controll the decay speed of the approximate sampling function.

  14. A Universal Generator for Bivariate Log-Concave Distributions

    OpenAIRE

    Hörmann, Wolfgang

    1995-01-01

    Different universal (also called automatic or black-box) methods have been suggested to sample from univariate log-concave distributions. The description of a universal generator for bivariate distributions has not been published up to now. The new algorithm for bivariate log-concave distributions is based on the method of transformed density rejection. In order to construct a hat function for a rejection algorithm the bivariate density is transformed by the logarithm into a concave function....

  15. Bivariate Rayleigh Distribution and its Properties

    Directory of Open Access Journals (Sweden)

    Ahmad Saeed Akhter

    2007-01-01

    Full Text Available Rayleigh (1880 observed that the sea waves follow no law because of the complexities of the sea, but it has been seen that the probability distributions of wave heights, wave length, wave induce pitch, wave and heave motions of the ships follow the Rayleigh distribution. At present, several different quantities are in use for describing the state of the sea; for example, the mean height of the waves, the root mean square height, the height of the “significant waves” (the mean height of the highest one-third of all the waves the maximum height over a given interval of the time, and so on. At present, the ship building industry knows less than any other construction industry about the service conditions under which it must operate. Only small efforts have been made to establish the stresses and motions and to incorporate the result of such studies in to design. This is due to the complexity of the problem caused by the extensive variability of the sea and the corresponding response of the ships. Although the problem appears feasible, yet it is possible to predict service conditions for ships in an orderly and relatively simple manner Rayleigh (1980 derived it from the amplitude of sound resulting from many independent sources. This distribution is also connected with one or two dimensions and is sometimes referred to as “random walk” frequency distribution. The Rayleigh distribution can be derived from the bivariate normal distribution when the variate are independent and random with equal variances. We try to construct bivariate Rayleigh distribution with marginal Rayleigh distribution function and discuss its fundamental properties.

  16. Causal networks clarify productivity-richness interrelations, bivariate plots do not

    Science.gov (United States)

    Grace, James B.; Adler, Peter B.; Harpole, W. Stanley; Borer, Elizabeth T.; Seabloom, Eric W.

    2014-01-01

    Perhaps no other pair of variables in ecology has generated as much discussion as species richness and ecosystem productivity, as illustrated by the reactions by Pierce (2013) and others to Adler et al.'s (2011) report that empirical patterns are weak and inconsistent. Adler et al. (2011) argued we need to move beyond a focus on simplistic bivariate relationships and test mechanistic, multivariate causal hypotheses. We feel the continuing debate over productivity–richness relationships (PRRs) provides a focused context for illustrating the fundamental difficulties of using bivariate relationships to gain scientific understanding.

  17. A Robust Skin Colour Segmentation Using Bivariate Pearson Type IIαα (Bivariate Beta) Mixture Model

    OpenAIRE

    B.N.Jagadesh; Srinivasa Rao, K.; Ch.Satyanarayana

    2012-01-01

    Probability distributions formulate the basic framework for developing several segmentation algorithms. Among the various segmentation algorithms, skin colour segmentation is one of the most important algorithms for human computer interaction. Due to various random factors influencing the colour space, there does not exist a unique algorithm which serve the purpose of all images. In this paper a novel and new skin colour segmentation algorithms is proposed based on bivariate Pearson type I...

  18. Recursively determined representing measures for bivariate truncated moment sequences

    CERN Document Server

    Curto, Raul E

    2012-01-01

    A theorem of Bayer and Teichmann implies that if a finite real multisequence \\beta = \\beta^(2d) has a representing measure, then the associated moment matrix M_d admits positive, recursively generated moment matrix extensions M_(d+1), M_(d+2),... For a bivariate recursively determinate M_d, we show that the existence of positive, recursively generated extensions M_(d+1),...,M_(2d-1) is sufficient for a measure. Examples illustrate that all of these extensions may be required to show that \\beta has a measure. We describe in detail a constructive procedure for determining whether such extensions exist. Under mild additional hypotheses, we show that M_d admits an extension M_(d+1) which has many of the properties of a positive, recursively generated extension.

  19. Bivariate Recursive Equations on Excess-of-loss Reinsurance

    Institute of Scientific and Technical Information of China (English)

    Jing Ping YANG; Shi Hong CHENG; Xiao Qian WANG

    2007-01-01

    This paper investigates bivariate recursive equations on excess-of-loss reinsurance.For an insurance portfolio, under the assumptions that the individual claim severity distribution has bounded continuous density and the number of claims belongs to R1(a,b) family, bivariate recursive equations for the joint distribution of the cedent's aggregate claims and the reinsurer's aggre gate claims are obtained.

  20. Modeling animal-vehicle collisions using diagonal inflated bivariate Poisson regression.

    Science.gov (United States)

    Lao, Yunteng; Wu, Yao-Jan; Corey, Jonathan; Wang, Yinhai

    2011-01-01

    Two types of animal-vehicle collision (AVC) data are commonly adopted for AVC-related risk analysis research: reported AVC data and carcass removal data. One issue with these two data sets is that they were found to have significant discrepancies by previous studies. In order to model these two types of data together and provide a better understanding of highway AVCs, this study adopts a diagonal inflated bivariate Poisson regression method, an inflated version of bivariate Poisson regression model, to fit the reported AVC and carcass removal data sets collected in Washington State during 2002-2006. The diagonal inflated bivariate Poisson model not only can model paired data with correlation, but also handle under- or over-dispersed data sets as well. Compared with three other types of models, double Poisson, bivariate Poisson, and zero-inflated double Poisson, the diagonal inflated bivariate Poisson model demonstrates its capability of fitting two data sets with remarkable overlapping portions resulting from the same stochastic process. Therefore, the diagonal inflated bivariate Poisson model provides researchers a new approach to investigating AVCs from a different perspective involving the three distribution parameters (λ(1), λ(2) and λ(3)). The modeling results show the impacts of traffic elements, geometric design and geographic characteristics on the occurrences of both reported AVC and carcass removal data. It is found that the increase of some associated factors, such as speed limit, annual average daily traffic, and shoulder width, will increase the numbers of reported AVCs and carcass removals. Conversely, the presence of some geometric factors, such as rolling and mountainous terrain, will decrease the number of reported AVCs.

  1. Stress-strength reliability for general bivariate distributions

    Directory of Open Access Journals (Sweden)

    Alaa H. Abdel-Hamid

    2016-10-01

    Full Text Available An expression for the stress-strength reliability R=P(X1bivariate distribution. Such distribution includes bivariate compound Weibull, bivariate compound Gompertz, bivariate compound Pareto, among others. In the parametric case, the maximum likelihood estimates of the parameters and reliability function R are obtained. In the non-parametric case, point and interval estimates of R are developed using Govindarajulu's asymptotic distribution-free method when X1 and X2 are dependent. An example is given when the population distribution is bivariate compound Weibull. Simulation is performed, based on different sample sizes to study the performance of estimates.

  2. Bivariate categorical data analysis using normal linear conditional multinomial probability model.

    Science.gov (United States)

    Sun, Bingrui; Sutradhar, Brajendra

    2015-02-10

    Bivariate multinomial data such as the left and right eyes retinopathy status data are analyzed either by using a joint bivariate probability model or by exploiting certain odds ratio-based association models. However, the joint bivariate probability model yields marginal probabilities, which are complicated functions of marginal and association parameters for both variables, and the odds ratio-based association model treats the odds ratios involved in the joint probabilities as 'working' parameters, which are consequently estimated through certain arbitrary 'working' regression models. Also, this later odds ratio-based model does not provide any easy interpretations of the correlations between two categorical variables. On the basis of pre-specified marginal probabilities, in this paper, we develop a bivariate normal type linear conditional multinomial probability model to understand the correlations between two categorical variables. The parameters involved in the model are consistently estimated using the optimal likelihood and generalized quasi-likelihood approaches. The proposed model and the inferences are illustrated through an intensive simulation study as well as an analysis of the well-known Wisconsin Diabetic Retinopathy status data.

  3. The bivariate Rogers Szegö polynomials

    Science.gov (United States)

    Chen, William Y. C.; Saad, Husam L.; Sun, Lisa H.

    2007-06-01

    We present an operator approach to deriving Mehler's formula and the Rogers formula for the bivariate Rogers-Szegö polynomials hn(x, y|q). The proof of Mehler's formula can be considered as a new approach to the nonsymmetric Poisson kernel formula for the continuous big q-Hermite polynomials Hn(x; a|q) due to Askey, Rahman and Suslov. Mehler's formula for hn(x, y|q) involves a 3phi2 sum and the Rogers formula involves a 2phi1 sum. The proofs of these results are based on parameter augmentation with respect to the q-exponential operator and the homogeneous q-shift operator in two variables. By extending recent results on the Rogers-Szegö polynomials hn(x|q) due to Hou, Lascoux and Mu, we obtain another Rogers-type formula for hn(x, y|q). Finally, we give a change of base formula for Hn(x; a|q) which can be used to evaluate some integrals by using the Askey-Wilson integral.

  4. The bivariate Rogers-Szegoe polynomials

    Energy Technology Data Exchange (ETDEWEB)

    Chen, William Y C [Center for Combinatorics, LPMC, Nankai University, Tianjin 300071 (China); Saad, Husam L [Center for Combinatorics, LPMC, Nankai University, Tianjin 300071 (China); Sun, Lisa H [Center for Combinatorics, LPMC, Nankai University, Tianjin 300071 (China)

    2007-06-08

    We present an operator approach to deriving Mehler's formula and the Rogers formula for the bivariate Rogers-Szegoe polynomials h{sub n}(x, y vertical bar q). The proof of Mehler's formula can be considered as a new approach to the nonsymmetric Poisson kernel formula for the continuous big q-Hermite polynomials H{sub n}(x; a vertical bar q) due to Askey, Rahman and Suslov. Mehler's formula for h{sub n}(x, y vertical bar q) involves a {sub 3}{phi}{sub 2} sum and the Rogers formula involves a {sub 2}{phi}{sub 1} sum. The proofs of these results are based on parameter augmentation with respect to the q-exponential operator and the homogeneous q-shift operator in two variables. By extending recent results on the Rogers-Szegoe polynomials h{sub n}(x vertical bar q) due to Hou, Lascoux and Mu, we obtain another Rogers-type formula for h{sub n}(x, y vertical bar q). Finally, we give a change of base formula for H{sub n}(x; a vertical bar q) which can be used to evaluate some integrals by using the Askey-Wilson integral.

  5. Dyadic Bivariate Wavelet Multipliers in L2(R2)

    Institute of Scientific and Technical Information of China (English)

    Zhong Yan LI; Xian Liang SHI

    2011-01-01

    The single 2 dilation wavelet multipliers in one-dimensional case and single A-dilation (where A is any expansive matrix with integer entries and |detA|=2)wavelet multipliers in twodimensional case were completely characterized by Wutam Consortium(1998)and Li Z.,et al.(2010).But there exist no results on multivariate wavelet multipliers corresponding to integer expansive dilation.matrix with the absolute value of determinant not 2 in L2(R2).In this paper,we choose 2I2=(0202)as the dilation matrix and consider the 2I2-dilation multivariate wavelet Ψ={ψ1,ψ2,ψ3}(which is called a dyadic bivariate wavelet)multipliers.Here we call a measurable function family f={f1,f2,f3}a dyadic bivariate wavelet multiplier if Ψ1={F-1(f1ψ1),F-1(f2ψ2),F-1(f3ψ3)} is a dyadic bivariate wavelet for any dyadic bivariate wavelet Ψ={ψ1,ψ2,ψ3},where(f)and,F-1 denote the Fourier transform and the inverse transform of function f respectively.We study dyadic bivariate wavelet multipliers,and give some conditions for dyadic bivariate wavelet multipliers.We also give concrete forms of linear phases of dyadic MRA bivariate wavelets.

  6. A Bivariate Analogue to the Composed Product of Polynomials

    Institute of Scientific and Technical Information of China (English)

    Donald Mills; Kent M. Neuerburg

    2003-01-01

    The concept of a composed product for univariate polynomials has been explored extensively by Brawley, Brown, Carlitz, Gao,Mills, et al. Starting with these fundamental ideas andutilizing fractional power series representation(in particular, the Puiseux expansion) of bivariate polynomials, we generalize the univariate results. We define a bivariate composed sum,composed multiplication,and composed product (based on function composition). Further, we investigate the algebraic structure of certain classes of bivariate polynomials under these operations. We also generalize a result of Brawley and Carlitz concerningthe decomposition of polynomials into irreducibles.

  7. SHAPE-PRESERVING BIVARIATE POLYNOMIAL APPROXIMATION IN C([-1,1]×[-1,1])

    Institute of Scientific and Technical Information of China (English)

    Sorin G. Gal

    2002-01-01

    In this paper we construct bivariate polynomials attached to a bivariate function, that approximate with Jackson-type rate involving a bivariate Ditzian-Totik ω2-modulus of smoothness and preserve some natural kinds of bivariate monotonicity and convexity of function.The result extends that in univariate case-of D. Leviatan in [5-6], improves that in bivariate case of the author in [3] and in some special cases, that in bivariate case of G. Anastassiou in [1].

  8. Recursive Numerical Evaluation of the Cumulative Bivariate Normal Distribution

    CERN Document Server

    Meyer, Christian

    2010-01-01

    We propose an algorithm for evaluation of the cumulative bivariate normal distribution, building upon Marsaglia's ideas for evaluation of the cumulative univariate normal distribution. The algorithm is mathematically transparent, delivers competitive performance and can easily be extended to arbitrary precision.

  9. Approximation of bivariate copulas by patched bivariate Fréchet copulas

    KAUST Repository

    Zheng, Yanting

    2011-03-01

    Bivariate Fréchet (BF) copulas characterize dependence as a mixture of three simple structures: comonotonicity, independence and countermonotonicity. They are easily interpretable but have limitations when used as approximations to general dependence structures. To improve the approximation property of the BF copulas and keep the advantage of easy interpretation, we develop a new copula approximation scheme by using BF copulas locally and patching the local pieces together. Error bounds and a probabilistic interpretation of this approximation scheme are developed. The new approximation scheme is compared with several existing copula approximations, including shuffle of min, checkmin, checkerboard and Bernstein approximations and exhibits better performance, especially in characterizing the local dependence. The utility of the new approximation scheme in insurance and finance is illustrated in the computation of the rainbow option prices and stop-loss premiums. © 2010 Elsevier B.V.

  10. Dissecting the correlation structure of a bivariate phenotype: common genes or shared environment?

    Indian Academy of Sciences (India)

    Saurabh Ghosh

    2005-08-01

    High correlations between two quantitative traits may be either due to common genetic factors or common environmental factors or a combination of both. In this study, we develop statistical methods to extract the genetic contribution to the total correlation between the components of a bivariate phenotype. Using data on bivariate phenotypes and marker genotypes for sib-pairs, we propose a test for linkage between a common QTL and a marker locus based on the conditional cross-sib trait correlations (trait 1 of sib 1 – trait 2 of sib 2 and conversely) given the identity-by-descent (i.b.d.) sharing at the marker locus. We use Monte-Carlo simulations to evaluate the performance of the proposed test under different trait parameters and quantitative trait distributions. An application of the method is illustrated using data on two alcohol-related phenotypes from a project on the collaborative study on the genetics of alcoholism.

  11. Remote Associates Test and Alpha Brain Waves

    Science.gov (United States)

    Haarmann, Henk J.; George, Timothy; Smaliy, Alexei; Dien, Joseph

    2012-01-01

    Previous studies found that performance on the remote associates test (RAT) improves after a period of incubation and that increased alpha brain waves over the right posterior brain predict the emergence of RAT insight solutions. We report an experiment that tested whether increased alpha brain waves during incubation improve RAT performance.…

  12. Interp olation by Bivariate Polynomials Based on Multivariate F-truncated Powers

    Institute of Scientific and Technical Information of China (English)

    Yuan Xue-mei

    2014-01-01

    The solvability of the interpolation by bivariate polynomials based on multivariate F-truncated powers is considered in this short note. It unifies the point-wise Lagrange interpolation by bivariate polynomials and the interpolation by bivari-ate polynomials based on linear integrals over segments in some sense.

  13. Color-shape associations revealed with implicit association tests.

    Directory of Open Access Journals (Sweden)

    Na Chen

    Full Text Available Kandinsky proposed a correspondence theory that suggests associations between specific colors and shapes (i.e., circle-blue, square-red, triangle-yellow. Makin and Wuerger tested the theory using the Implicit Association Test (IAT and did not find clear evidence for Kandinsky's color-shape associations among British participants. In the present study, we first replicated the previous study among Japanese participants and found similar results to those of Makin and Wuerger, showing little support for Kandinsky's theory. In the subsequent experiment, we tested another set of color-shape associations that had been revealed by using an explicit matching method (circle-red, square-blue, triangle-yellow in Japanese participants. The IAT tests showed that response times were significantly faster when circle-red, square-blue, and triangle-yellow combinations were mapped onto the same response key, rather than different key combinations, indicating that these color-shape combinations were encoded. These results provide the first empirical evidence that color-shape associations can be measured by indirect behavioral methods, and in particular, Japanese people's color-shape associations (circle-red, square-blue, triangle-yellow can be observed by both direct and indirect experimental methods.

  14. Color-shape associations revealed with implicit association tests.

    Science.gov (United States)

    Chen, Na; Tanaka, Kanji; Watanabe, Katsumi

    2015-01-01

    Kandinsky proposed a correspondence theory that suggests associations between specific colors and shapes (i.e., circle-blue, square-red, triangle-yellow). Makin and Wuerger tested the theory using the Implicit Association Test (IAT) and did not find clear evidence for Kandinsky's color-shape associations among British participants. In the present study, we first replicated the previous study among Japanese participants and found similar results to those of Makin and Wuerger, showing little support for Kandinsky's theory. In the subsequent experiment, we tested another set of color-shape associations that had been revealed by using an explicit matching method (circle-red, square-blue, triangle-yellow) in Japanese participants. The IAT tests showed that response times were significantly faster when circle-red, square-blue, and triangle-yellow combinations were mapped onto the same response key, rather than different key combinations, indicating that these color-shape combinations were encoded. These results provide the first empirical evidence that color-shape associations can be measured by indirect behavioral methods, and in particular, Japanese people's color-shape associations (circle-red, square-blue, triangle-yellow) can be observed by both direct and indirect experimental methods.

  15. A penalized likelihood approach for bivariate conditional normal models for dynamic co-expression analysis.

    Science.gov (United States)

    Chen, Jun; Xie, Jichun; Li, Hongzhe

    2011-03-01

    Gene co-expressions have been widely used in the analysis of microarray gene expression data. However, the co-expression patterns between two genes can be mediated by cellular states, as reflected by expression of other genes, single nucleotide polymorphisms, and activity of protein kinases. In this article, we introduce a bivariate conditional normal model for identifying the variables that can mediate the co-expression patterns between two genes. Based on this model, we introduce a likelihood ratio (LR) test and a penalized likelihood procedure for identifying the mediators that affect gene co-expression patterns. We propose an efficient computational algorithm based on iterative reweighted least squares and cyclic coordinate descent and have shown that when the tuning parameter in the penalized likelihood is appropriately selected, such a procedure has the oracle property in selecting the variables. We present simulation results to compare with existing methods and show that the LR-based approach can perform similarly or better than the existing method of liquid association and the penalized likelihood procedure can be quite effective in selecting the mediators. We apply the proposed method to yeast gene expression data in order to identify the kinases or single nucleotide polymorphisms that mediate the co-expression patterns between genes.

  16. Simultaneous estimation of parameters in the bivariate Emax model.

    Science.gov (United States)

    Magnusdottir, Bergrun T; Nyquist, Hans

    2015-12-10

    In this paper, we explore inference in multi-response, nonlinear models. By multi-response, we mean models with m > 1 response variables and accordingly m relations. Each parameter/explanatory variable may appear in one or more of the relations. We study a system estimation approach for simultaneous computation and inference of the model and (co)variance parameters. For illustration, we fit a bivariate Emax model to diabetes dose-response data. Further, the bivariate Emax model is used in a simulation study that compares the system estimation approach to equation-by-equation estimation. We conclude that overall, the system estimation approach performs better for the bivariate Emax model when there are dependencies among relations. The stronger the dependencies, the more we gain in precision by using system estimation rather than equation-by-equation estimation.

  17. BIVARIATE LAGRANGE-TYPE VECTOR VALUED RATIONAL INTERPOLANTS

    Institute of Scientific and Technical Information of China (English)

    Chuan-qing Gu; Gong-qing Zhu

    2002-01-01

    An axiomatic definition to bivariate vector valued rational interpolation on distinct plane interpolation points is at first presented in this paper. A two-variable vector valued rational interpolation formula is explicitly constructed in the following form: the determinantal formulas for denominator scalar polynomials and for numerator vector polynomials,which possess Lagrange-type basic function expressions. A practical criterion of existence and uniqueness for interpolation is obtained. In contrast to the underlying method, the method of bivariate Thiele-type vector valued rational interpolation is reviewed.

  18. TREAT (TREe-based Association Test)

    Science.gov (United States)

    TREAT is an R package for detecting complex joint effects in case-control studies. The test statistic is derived from a tree-structure model by recursive partitioning the data. Ultra-fast algorithm is designed to evaluate the significance of association be

  19. Bayesian framework for parametric bivariate accelerated lifetime modeling and its application to hospital acquired infections.

    Science.gov (United States)

    Bilgili, D; Ryu, D; Ergönül, Ö; Ebrahimi, N

    2016-03-01

    Infectious diseases that can be spread directly or indirectly from one person to another are caused by pathogenic microorganisms such as bacteria, viruses, parasites, or fungi. Infectious diseases remain one of the greatest threats to human health and the analysis of infectious disease data is among the most important application of statistics. In this article, we develop Bayesian methodology using parametric bivariate accelerated lifetime model to study dependency between the colonization and infection times for Acinetobacter baumannii bacteria which is leading cause of infection among the hospital infection agents. We also study their associations with covariates such as age, gender, apache score, antibiotics use 3 months before admission and invasive mechanical ventilation use. To account for singularity, we use Singular Bivariate Extreme Value distribution to model residuals in Bivariate Accelerated lifetime model under the fully Bayesian framework. We analyze a censored data related to the colonization and infection collected in five major hospitals in Turkey using our methodology. The data analysis done in this article is for illustration of our proposed method and can be applied to any situation that our model can be used.

  20. A vector of quarters representation for bivariate time series

    NARCIS (Netherlands)

    Ph.H.B.F. Franses (Philip Hans)

    1995-01-01

    textabstractIn this paper it is shown that several models for a bivariate nonstationary quarterly time series are nested in a vector autoregression with cointegration restrictions for the eight annual series of quarterly observations. Or, the Granger Representation Theorem is extended to incorporate

  1. Bivariate support of forward libor and swap rates

    NARCIS (Netherlands)

    Jamshidian, Farshid

    2008-01-01

    Based on a certain notion of "prolific process," we find an explicit expression for the bivariate (topological) support of the solution to a particular class of 2 × 2 stochastic differential equations that includes those of the three-period "lognormal" Libor and swap market models. This yields that

  2. Bivariate Blending Thiele-Werner's Osculatory Rational Interpolation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Both the expansive Newton's interpolating polynomial and the Thiele-Werner's interpolation are used to construct a kind of bivariate blending Thiele-Werner's osculatory rational interpolation. A recursive algorithm and its characteristic properties are given. An error estimation is obtained and a numerical example is illustrated.

  3. On limit relations between some families of bivariate hypergeometric orthogonal polynomials

    Science.gov (United States)

    Area, I.; Godoy, E.

    2013-01-01

    In this paper we deal with limit relations between bivariate hypergeometric polynomials. We analyze the limit relation from trinomial distribution to bivariate Gaussian distribution, obtaining the limit transition from the second-order partial difference equation satisfied by bivariate hypergeometric Kravchuk polynomials to the second-order partial differential equation verified by bivariate hypergeometric Hermite polynomials. As a consequence the limit relation between both families of orthogonal polynomials is established. A similar analysis between bivariate Hahn and bivariate Appell orthogonal polynomials is also presented.

  4. Factors Associated with HIV Testing History among Pregnant Women and Their Partners in Georgia: The ANRS 12127 Prenahtest Trial

    Directory of Open Access Journals (Sweden)

    Maia Butsashvili

    2014-01-01

    Full Text Available Despite the benefits of timely diagnosis of HIV infection and the wide availability of VCT services, the acceptance of HIV testing and counseling still remains a challenge in Georgia. The goal of our study was to assess the history of HIV testing and associated factors among pregnant women. The recruitment of study participants took place during routine antenatal care visits at one of the large Maternity Hospitals in Tbilisi, capital of Georgia. A total of 491 pregnant women were included in the sample. More than a third of women (38.5% reported that they were tested for HIV before the current pregnancy and almost all of them (91.5% were tested during previous pregnancies. Bivariate analysis revealed statistically significant association of women’s history of HIV testing with age, education level, remunerated activity, history of STI, and multiparity. In multivariate analysis, the only independent predictor of being HIV tested was ever being pregnant. In conclusion, HIV testing history among women at reproductive age was poor in Georgia. Women mostly received HIV testing at prenatal centers. Efforts should be made to promote HIV testing in primary care settings, which would increase its acceptability and overall testing rate in the population.

  5. A bivariate quantitative genetic model for a threshold trait and a survival trait

    Directory of Open Access Journals (Sweden)

    Damgaard Lars

    2006-11-01

    Full Text Available Abstract Many of the functional traits considered in animal breeding can be analyzed as threshold traits or survival traits with examples including disease traits, conformation scores, calving difficulty and longevity. In this paper we derive and implement a bivariate quantitative genetic model for a threshold character and a survival trait that are genetically and environmentally correlated. For the survival trait, we considered the Weibull log-normal animal frailty model. A Bayesian approach using Gibbs sampling was adopted in which model parameters were augmented with unobserved liabilities associated with the threshold trait. The fully conditional posterior distributions associated with parameters of the threshold trait reduced to well known distributions. For the survival trait the two baseline Weibull parameters were updated jointly by a Metropolis-Hastings step. The remaining model parameters with non-normalized fully conditional distributions were updated univariately using adaptive rejection sampling. The Gibbs sampler was tested in a simulation study and illustrated in a joint analysis of calving difficulty and longevity of dairy cattle. The simulation study showed that the estimated marginal posterior distributions covered well and placed high density to the true values used in the simulation of data. The data analysis of calving difficulty and longevity showed that genetic variation exists for both traits. The additive genetic correlation was moderately favorable with marginal posterior mean equal to 0.37 and 95% central posterior credibility interval ranging between 0.11 and 0.61. Therefore, this study suggests that selection for improving one of the two traits will be beneficial for the other trait as well.

  6. A bivariate quantitative genetic model for a threshold trait and a survival trait.

    Science.gov (United States)

    Damgaard, Lars Holm; Korsgaard, Inge Riis

    2006-01-01

    Many of the functional traits considered in animal breeding can be analyzed as threshold traits or survival traits with examples including disease traits, conformation scores, calving difficulty and longevity. In this paper we derive and implement a bivariate quantitative genetic model for a threshold character and a survival trait that are genetically and environmentally correlated. For the survival trait, we considered the Weibull log-normal animal frailty model. A Bayesian approach using Gibbs sampling was adopted in which model parameters were augmented with unobserved liabilities associated with the threshold trait. The fully conditional posterior distributions associated with parameters of the threshold trait reduced to well known distributions. For the survival trait the two baseline Weibull parameters were updated jointly by a Metropolis-Hastings step. The remaining model parameters with non-normalized fully conditional distributions were updated univariately using adaptive rejection sampling. The Gibbs sampler was tested in a simulation study and illustrated in a joint analysis of calving difficulty and longevity of dairy cattle. The simulation study showed that the estimated marginal posterior distributions covered well and placed high density to the true values used in the simulation of data. The data analysis of calving difficulty and longevity showed that genetic variation exists for both traits. The additive genetic correlation was moderately favorable with marginal posterior mean equal to 0.37 and 95% central posterior credibility interval ranging between 0.11 and 0.61. Therefore, this study suggests that selection for improving one of the two traits will be beneficial for the other trait as well.

  7. Univariate and Bivariate Empirical Mode Decomposition for Postural Stability Analysis

    Directory of Open Access Journals (Sweden)

    Jacques Duchêne

    2008-05-01

    Full Text Available The aim of this paper was to compare empirical mode decomposition (EMD and two new extended methods of  EMD named complex empirical mode decomposition (complex-EMD and bivariate empirical mode decomposition (bivariate-EMD. All methods were used to analyze stabilogram center of pressure (COP time series. The two new methods are suitable to be applied to complex time series to extract complex intrinsic mode functions (IMFs before the Hilbert transform is subsequently applied on the IMFs. The trace of the analytic IMF in the complex plane has a circular form, with each IMF having its own rotation frequency. The area of the circle and the average rotation frequency of IMFs represent efficient indicators of the postural stability status of subjects. Experimental results show the effectiveness of these indicators to identify differences in standing posture between groups.

  8. Non-parametric causal inference for bivariate time series

    CERN Document Server

    McCracken, James M

    2015-01-01

    We introduce new quantities for exploratory causal inference between bivariate time series. The quantities, called penchants and leanings, are computationally straightforward to apply, follow directly from assumptions of probabilistic causality, do not depend on any assumed models for the time series generating process, and do not rely on any embedding procedures; these features may provide a clearer interpretation of the results than those from existing time series causality tools. The penchant and leaning are computed based on a structured method for computing probabilities.

  9. Numerical Integration Based on Bivariate Quartic Quasi-Interpolation Operators

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this paper, we propose a method to deal with numerical integral by using two kinds of C2 quasi-interpolation operators on the bivariate spline space, and also discuss the convergence properties and error estimates. Moreover, the proposed method is applied to the numerical evaluation of 2-D singular integrals. Numerical experiments will be carried out and the results will be compared with some previously published results.

  10. Mortality as a bivariate function of age and size in indeterminate growers

    DEFF Research Database (Denmark)

    Colchero, Fernando; Schaible, Ralf

    2014-01-01

    developed a model that treats age- and size-specific mortality as a bivariate process. This method facilitates the exploration of the underlying (unobserved) contributions of age and size to mortality. We show that, in theory, a population can show declining mortality with age and size while the underlying...... be made using a simple Bayesian model, and how all of the mortality parameters are accurately retrieved. We then apply the methods to published datasets on water pythons and freshwater mussels and test different hypotheses regarding the effects of age and size on mortality. In both cases we found age...

  11. An integrated user-friendly ArcMAP tool for bivariate statistical modeling in geoscience applications

    Science.gov (United States)

    Jebur, M. N.; Pradhan, B.; Shafri, H. Z. M.; Yusof, Z.; Tehrany, M. S.

    2014-10-01

    Modeling and classification difficulties are fundamental issues in natural hazard assessment. A geographic information system (GIS) is a domain that requires users to use various tools to perform different types of spatial modeling. Bivariate statistical analysis (BSA) assists in hazard modeling. To perform this analysis, several calculations are required and the user has to transfer data from one format to another. Most researchers perform these calculations manually by using Microsoft Excel or other programs. This process is time consuming and carries a degree of uncertainty. The lack of proper tools to implement BSA in a GIS environment prompted this study. In this paper, a user-friendly tool, BSM (bivariate statistical modeler), for BSA technique is proposed. Three popular BSA techniques such as frequency ratio, weights-of-evidence, and evidential belief function models are applied in the newly proposed ArcMAP tool. This tool is programmed in Python and is created by a simple graphical user interface, which facilitates the improvement of model performance. The proposed tool implements BSA automatically, thus allowing numerous variables to be examined. To validate the capability and accuracy of this program, a pilot test area in Malaysia is selected and all three models are tested by using the proposed program. Area under curve is used to measure the success rate and prediction rate. Results demonstrate that the proposed program executes BSA with reasonable accuracy. The proposed BSA tool can be used in numerous applications, such as natural hazard, mineral potential, hydrological, and other engineering and environmental applications.

  12. Variations in the Bivariate Brightness Distribution with different galaxy types

    CERN Document Server

    Cross, N; Lemon, D; Liske, J; Cross, Nicholas; Driver, Simon; Lemon, David; Liske, Jochen

    2002-01-01

    We present Bivariate Brightness Distributions (BBDs) for four spectral types discriminated by the 2dFGRS. We discuss the photometry and completeness of the 2dFGRS using a deep, wide-field CCD imaging survey. We find that there is a strong luminosity-surface brightness correlation amongst galaxies with medium to strong emission features, with gradient $\\beta_{\\mu}=0.25\\pm0.05$ and width $\\sigma_{\\mu}=0.56\\pm0.01$. Strong absorption line galaxies, show a bimodal distribution, with no correlation between luminosity and surface brightness.

  13. Covariance Association Test (CVAT) Identifies Genetic Markers Associated with Schizophrenia in Functionally Associated Biological Processes

    DEFF Research Database (Denmark)

    Rohde, Palle Duun; Demontis, Ditte; Castro Dias Cuyabano, Beatriz;

    2016-01-01

    Schizophrenia is a psychiatric disorder with large personal and social costs, and understanding the genetic etiology is important. Such knowledge can be obtained by testing the association between a disease phenotype and individual genetic markers; however, such single-marker methods have limited...... power to detect genetic markers with small effects. Instead, aggregating genetic markers based on biological information might increase the power to identify sets of genetic markers of etiological significance. Several set test methods have been proposed: Here we propose a new set test derived from...... genomic best linear unbiased prediction (GBLUP), the covariance association test (CVAT). We compared the performance of CVAT to other commonly used set tests. The comparison was conducted using a simulated study population having the same genetic parameters as for schizophrenia. We found that CVAT...

  14. Comparison of simple pooling and bivariate model used in meta-analyses of diagnos-tic test accuracy published in Chinese journals%简单合并模型与双变量模型在诊断试验Meta分析中的使用现状调查

    Institute of Scientific and Technical Information of China (English)

    黄元升; 杨智荣; 詹思延

    2015-01-01

    目的::调查2014年1月至11月国内期刊发表的诊断试验准确性( diagnostic test accuracy,DTA) Meta分析中简单合并模型与双变量模型的使用现状,分析两模型间结果的差异性,并探讨这种差异性与研究间异质性大小的关系。方法:对《中国生物医学文献数据库》2014年1月至11月收录的文献进行检索,纳入DTA Meta分析,描述模型使用的相关信息,提取四格表数据,使用简单合并模型和双变量模型进行重分析,用非参数检验比较模型结果间差值,定性探究灵敏度、特异度异质性大小与结果间差值的关系。结果:共纳入55篇文章,包括58个DTA Meta分析,其中25个Meta分析用于重分析。简单合并模型与双变量模型的使用比例分别为90.9%(50/55)、1.8%(1/55),使用其他合并模型或未合并灵敏度和特异度的文献比例为7.3%(4/55)。在50篇使用简单合并模型合并灵敏度和特异度的文章中,41篇(82.0%)存在误用Meta-disc软件的可能。两种模型所得灵敏度、特异度差值中位数均为0.011(P75%. Conclusion:Most DTA meta-analyses published in Chinese journals(January to November, 2014) combine the sensitivity and specificity by simple pooling. Meta-disc software can pool the sensitivity and specificity only through fixed-effect model, but a high proportion of authors think it can implement random-effect model. Simple pooling tends to underestimate the results compared with bivariate model. The greater the between-study variance is, the more likely the simple pooling has larger deviation. It is necessary to increase the knowledge level of statistical methods and software for meta-analyses of DTA data.

  15. THE INSTABILITY DEGREE IN THE DIEMNSION OF SPACES OF BIVARIATE SPLINE

    Institute of Scientific and Technical Information of China (English)

    Zhiqiang Xu; Renhong Wang

    2002-01-01

    In this paper, the dimension of the spaces of bivariate spline with degree less that 2r and smoothness order r on the Morgan-Scott triangulation is considered. The concept of the instability degree in the dimension of spaces of bivariate spline is presented. The results in the paper make us conjecture the instability degree in the dimension of spaces of bivariate spline is infinity.

  16. THE NORMAL BIVARIATE DENSITY FUNCTION AND ITS APPLICATIONS TO WEAPON SYSTEMS ANALYSIS, A REVIEW

    Science.gov (United States)

    The normal bivariate density function is derived from a priori considerations. It is discussed in terms of probability area in a plane, and as a...correlation surface. Several numerical methods of solving the normal bivariate distribution double integral are presented, and a curve is included for...given specific mathematical treatment. An Appendix examines the elliptical properties of normally correlated distributions. The investigation has resulted in a reference paper for the normal bivariate density function.

  17. THE JOINT DISTRIBUTION OF BIVARIATE EXPONENTIAL UNDER LINEARLY RELATED MODEL

    Directory of Open Access Journals (Sweden)

    Norou Diawara

    2010-09-01

    Full Text Available In this paper, fundamental results of the joint distribution of the bivariate exponential distributions are established.  The positive support multivariate distribution theory is important in reliability and survival analysis, and we applied it to the case where more than one failure or survival is observed in a given study. Usually, the multivariate distribution is restricted to those with marginal distributions of a specified and familiar lifetime family. The family of exponential distribution contains the absolutely continuous and discrete case models with a nonzero probability on a set of measure zero. Examples are given, and estimators are developed and applied to simulated data. Our findings generalize substantially known results in the literature, provide flexible and novel approach for modeling related events that can occur simultaneously from one based event.

  18. Counterfactual Distributions in Bivariate Models—A Conditional Quantile Approach

    Directory of Open Access Journals (Sweden)

    Javier Alejo

    2015-11-01

    Full Text Available This paper proposes a methodology to incorporate bivariate models in numerical computations of counterfactual distributions. The proposal is to extend the works of Machado and Mata (2005 and Melly (2005 using the grid method to generate pairs of random variables. This contribution allows incorporating the effect of intra-household decision making in counterfactual decompositions of changes in income distribution. An application using data from five latin american countries shows that this approach substantially improves the goodness of fit to the empirical distribution. However, the exercise of decomposition is less conclusive about the performance of the method, which essentially depends on the sample size and the accuracy of the regression model.

  19. Efficient estimation of semiparametric copula models for bivariate survival data

    KAUST Repository

    Cheng, Guang

    2014-01-01

    A semiparametric copula model for bivariate survival data is characterized by a parametric copula model of dependence and nonparametric models of two marginal survival functions. Efficient estimation for the semiparametric copula model has been recently studied for the complete data case. When the survival data are censored, semiparametric efficient estimation has only been considered for some specific copula models such as the Gaussian copulas. In this paper, we obtain the semiparametric efficiency bound and efficient estimation for general semiparametric copula models for possibly censored data. We construct an approximate maximum likelihood estimator by approximating the log baseline hazard functions with spline functions. We show that our estimates of the copula dependence parameter and the survival functions are asymptotically normal and efficient. Simple consistent covariance estimators are also provided. Numerical results are used to illustrate the finite sample performance of the proposed estimators. © 2013 Elsevier Inc.

  20. Testing non-associative quantum mechanics

    CERN Document Server

    Bojowald, Martin; Buyukcam, Umut

    2015-01-01

    The familiar concepts of state vectors and operators in quantum mechanics rely on associative products of observables. However, these notions do not apply to some exotic systems such as magnetic monopoles, which have long been known to lead to non-associative algebras. Their quantum physics has remained obscure. This letter presents the first derivation of potentially testable physical results in non-associative quantum mechanics, based on effective potentials. They imply new effects which cannot be mimicked in usual quantum mechanics with standard magnetic fields.

  1. Comparing Johnson’s SBB, Weibull and Logit-Logistic bivariate distributions for modeling tree diameters and heights using copulas

    Directory of Open Access Journals (Sweden)

    Jose Javier Gorgoso-Varela

    2016-04-01

    Full Text Available Aim of study: In this study we compare the accuracy of three bivariate distributions: Johnson’s SBB, Weibull-2P and LL-2P functions for characterizing the joint distribution of tree diameters and heights.Area of study: North-West of Spain.Material and methods: Diameter and height measurements of 128 plots of pure and even-aged Tasmanian blue gum (Eucalyptus globulus Labill. stands located in the North-west of Spain were considered in the present study. The SBB bivariate distribution was obtained from SB marginal distributions using a Normal Copula based on a four-parameter logistic transformation. The Plackett Copula was used to obtain the bivariate models from the Weibull and Logit-logistic univariate marginal distributions. The negative logarithm of the maximum likelihood function was used to compare the results and the Wilcoxon signed-rank test was used to compare the related samples of these logarithms calculated for each sample plot and each distribution.Main results: The best results were obtained by using the Plackett copula and the best marginal distribution was the Logit-logistic.Research highlights: The copulas used in this study have shown a good performance for modeling the joint distribution of tree diameters and heights. They could be easily extended for modelling multivariate distributions involving other tree variables, such as tree volume or biomass.

  2. 一种新形式的二元混合有理插值%New Approach to Bivariate Blending Rational Interpolants

    Institute of Scientific and Technical Information of China (English)

    邹乐; 唐烁

    2011-01-01

    Newton's polynomial interpolation may be the favorite linear interpolation, associated continued fractions interpolation is a new type nonlinear interpolation. We use those two interpolation to construct a new kind of bivariate blending rational interpolants.Characteristic theorem is discussed. We give some new blending interpolation formulae.

  3. Convex preserving scattered data interpolation using bivariate C1 cubic splines

    Science.gov (United States)

    Lai, Ming-Jun

    2000-07-01

    We use bivariate C1 cubic splines to deal with convexity preserving scattered data interpolation problem. Using a necessary and sufficient condition on Bernstein-Bézier polynomials, we set the convexity-preserving interpolation problem into a quadratically constraint quadratic programming problem. We show the existence of convexity preserving interpolatory surfaces under certain conditions on the data. That is, under certain conditions on the data, there always exists a convexity preservation C1 cubic spline interpolation if the triangulation is refined sufficiently many times. We then replace the quadratical constrains by three linear constrains and formulate the problem into linearly constraint quadratic programming problems in order to be able to solve it easily. Certainly, the existence of convexity preserving interpolatory surfaces is equivalent to the feasibility of the linear constrains. We present a numerical experiment to test which of these three linear constraints performs the best.

  4. Bi-variable damage model for fatigue life prediction of metal components

    Institute of Scientific and Technical Information of China (English)

    Miao Zhang; Qing-Chun Meng; Xing Zhang; Wei-Ping Hu

    2011-01-01

    Based on the theory of continuum damage mechanics, a bi-variable damage mechanics model is developed, which, according to thermodynamics, is accessible to derivation of damage driving force, damage evolution equation and damage evolution criteria. Furthermore, damage evolution equations of time rate are established by the generalized Drucker's postulate. The damage evolution equation of cycle rate is obtained by integrating the time damage evolution equations, and the fatigue life prediction method for smooth specimens under repeated loading with constant strain amplitude is constructed. Likewise, for notched specimens under the repeated loading with constant strain amplitude, the fatigue life prediction method is obtained on the ground of the theory of conservative integral in damage mechanics. Thus, the material parameters in the damage evolution equation can be obtained by reference to the fatigue test results of standard specimens with stress concentration factor equal to 1, 2 and 3.

  5. Pleiotropic locus for emotion recognition and amygdala volume identified using univariate and bivariate linkage

    Science.gov (United States)

    Knowles, Emma E. M.; McKay, D. Reese; Kent, Jack W.; Sprooten, Emma; Carless, Melanie A.; Curran, Joanne E.; de Almeida, Marcio A. A.; Dyer, Thomas D.; Göring, Harald H. H.; Olvera, Rene; Duggirala, Ravi; Fox, Peter; Almasy, Laura; Blangero, John; Glahn, David. C.

    2014-01-01

    The role of the amygdala in emotion recognition is well established and separately each trait has been shown to be highly heritable, but the potential role of common genetic influences on both traits has not been explored. Here we present an investigation of the pleiotropic influences of amygdala and emotion recognition in a sample of randomly selected, extended pedigrees (N = 858). Using a combination of univariate and bivariate linkage we found a pleiotropic region for amygdala and emotion recognition on 4q26 (LOD = 4.34). Association analysis conducted in the region underlying the bivariate linkage peak revealed a variant meeting the corrected significance level (pBonferroni = 5.01×10−05) within an intron of PDE5A (rs2622497, Χ2 =16.67, p = 4.4×10−05) as being jointly influential on both traits. PDE5A has been implicated previously in recognition-memory deficits and is expressed in subcortical structures that are thought to underlie memory ability including the amygdala. The present paper extends our understanding of the shared etiology between amygdala and emotion recognition by showing that the overlap between the two traits is due, at least in part, to common genetic influences. Moreover, the present paper identifies a pleiotropic locus for the two traits and an associated variant, which localizes the genetic signal even more precisely. These results, when taken in the context of previous research, highlight the potential utility of PDE5-inhibitors for ameliorating emotion-recognition deficits in populations including, but not exclusively, those individuals suffering from mental or neurodegenerative illness. PMID:25322361

  6. An integrated user-friendly ArcMAP tool for bivariate statistical modelling in geoscience applications

    Science.gov (United States)

    Jebur, M. N.; Pradhan, B.; Shafri, H. Z. M.; Yusoff, Z. M.; Tehrany, M. S.

    2015-03-01

    Modelling and classification difficulties are fundamental issues in natural hazard assessment. A geographic information system (GIS) is a domain that requires users to use various tools to perform different types of spatial modelling. Bivariate statistical analysis (BSA) assists in hazard modelling. To perform this analysis, several calculations are required and the user has to transfer data from one format to another. Most researchers perform these calculations manually by using Microsoft Excel or other programs. This process is time-consuming and carries a degree of uncertainty. The lack of proper tools to implement BSA in a GIS environment prompted this study. In this paper, a user-friendly tool, bivariate statistical modeler (BSM), for BSA technique is proposed. Three popular BSA techniques, such as frequency ratio, weight-of-evidence (WoE), and evidential belief function (EBF) models, are applied in the newly proposed ArcMAP tool. This tool is programmed in Python and created by a simple graphical user interface (GUI), which facilitates the improvement of model performance. The proposed tool implements BSA automatically, thus allowing numerous variables to be examined. To validate the capability and accuracy of this program, a pilot test area in Malaysia is selected and all three models are tested by using the proposed program. Area under curve (AUC) is used to measure the success rate and prediction rate. Results demonstrate that the proposed program executes BSA with reasonable accuracy. The proposed BSA tool can be used in numerous applications, such as natural hazard, mineral potential, hydrological, and other engineering and environmental applications.

  7. An integrated user-friendly ArcMAP tool for bivariate statistical modeling in geoscience applications

    Directory of Open Access Journals (Sweden)

    M. N. Jebur

    2014-10-01

    Full Text Available Modeling and classification difficulties are fundamental issues in natural hazard assessment. A geographic information system (GIS is a domain that requires users to use various tools to perform different types of spatial modeling. Bivariate statistical analysis (BSA assists in hazard modeling. To perform this analysis, several calculations are required and the user has to transfer data from one format to another. Most researchers perform these calculations manually by using Microsoft Excel or other programs. This process is time consuming and carries a degree of uncertainty. The lack of proper tools to implement BSA in a GIS environment prompted this study. In this paper, a user-friendly tool, BSM (bivariate statistical modeler, for BSA technique is proposed. Three popular BSA techniques such as frequency ratio, weights-of-evidence, and evidential belief function models are applied in the newly proposed ArcMAP tool. This tool is programmed in Python and is created by a simple graphical user interface, which facilitates the improvement of model performance. The proposed tool implements BSA automatically, thus allowing numerous variables to be examined. To validate the capability and accuracy of this program, a pilot test area in Malaysia is selected and all three models are tested by using the proposed program. Area under curve is used to measure the success rate and prediction rate. Results demonstrate that the proposed program executes BSA with reasonable accuracy. The proposed BSA tool can be used in numerous applications, such as natural hazard, mineral potential, hydrological, and other engineering and environmental applications.

  8. Semantic Search in the Remote Associates Test.

    Science.gov (United States)

    Davelaar, Eddy J

    2015-07-01

    Searching through semantic memory may involve the use of several retrieval cues. In a verbal fluency task, the set of available cues is limited and every candidate word is a target. Individuals exhibit clustering behavior as predicted by optimal foraging theory. In another semantic search task, the remote associates task (RAT), three cues are presented and a single target word has to be found. Whereas the task has been widely studied as a task of creativity or insight problem solving, in this article, the RAT is treated as a semantic retrieval task and assessed from the perspective of information foraging theory. Experiments are presented that address the superadditive combination of cues and the anti-clustering behavior in the recall sequence. A new type of search behavior in the RAT is put forward that involves maximizing the difference in activation between target and distractors. This type of search is advantageous when the target is weak and cue patches are contaminated with strong competitors.

  9. Bivariate Rainfall and Runoff Analysis Using Entropy and Copula Theories

    Directory of Open Access Journals (Sweden)

    Lan Zhang

    2012-09-01

    Full Text Available Multivariate hydrologic frequency analysis has been widely studied using: (1 commonly known joint distributions or copula functions with the assumption of univariate variables being independently identically distributed (I.I.D. random variables; or (2 directly applying the entropy theory-based framework. However, for the I.I.D. univariate random variable assumption, the univariate variable may be considered as independently distributed, but it may not be identically distributed; and secondly, the commonly applied Pearson’s coefficient of correlation (g is not able to capture the nonlinear dependence structure that usually exists. Thus, this study attempts to combine the copula theory with the entropy theory for bivariate rainfall and runoff analysis. The entropy theory is applied to derive the univariate rainfall and runoff distributions. It permits the incorporation of given or known information, codified in the form of constraints and results in a universal solution of univariate probability distributions. The copula theory is applied to determine the joint rainfall-runoff distribution. Application of the copula theory results in: (i the detection of the nonlinear dependence between the correlated random variables-rainfall and runoff, and (ii capturing the tail dependence for risk analysis through joint return period and conditional return period of rainfall and runoff. The methodology is validated using annual daily maximum rainfall and the corresponding daily runoff (discharge data collected from watersheds near Riesel, Texas (small agricultural experimental watersheds and Cuyahoga River watershed, Ohio.

  10. Bivariate ensemble model output statistics approach for joint forecasting of wind speed and temperature

    Science.gov (United States)

    Baran, Sándor; Möller, Annette

    2017-02-01

    Forecast ensembles are typically employed to account for prediction uncertainties in numerical weather prediction models. However, ensembles often exhibit biases and dispersion errors, thus they require statistical post-processing to improve their predictive performance. Two popular univariate post-processing models are the Bayesian model averaging (BMA) and the ensemble model output statistics (EMOS). In the last few years, increased interest has emerged in developing multivariate post-processing models, incorporating dependencies between weather quantities, such as for example a bivariate distribution for wind vectors or even a more general setting allowing to combine any types of weather variables. In line with a recently proposed approach to model temperature and wind speed jointly by a bivariate BMA model, this paper introduces an EMOS model for these weather quantities based on a bivariate truncated normal distribution. The bivariate EMOS model is applied to temperature and wind speed forecasts of the 8-member University of Washington mesoscale ensemble and the 11-member ALADIN-HUNEPS ensemble of the Hungarian Meteorological Service and its predictive performance is compared to the performance of the bivariate BMA model and a multivariate Gaussian copula approach, post-processing the margins with univariate EMOS. While the predictive skills of the compared methods are similar, the bivariate EMOS model requires considerably lower computation times than the bivariate BMA method.

  11. Comparison of Model Reliabilities from Single-Step and Bivariate Blending Methods

    DEFF Research Database (Denmark)

    Taskinen, Matti; Mäntysaari, Esa; Lidauer, Martin;

    2013-01-01

    Model based reliabilities in genetic evaluation are compared between three methods: animal model BLUP, single-step BLUP, and bivariate blending after genomic BLUP. The original bivariate blending is revised in this work to better account animal models. The study data is extracted from the product......Model based reliabilities in genetic evaluation are compared between three methods: animal model BLUP, single-step BLUP, and bivariate blending after genomic BLUP. The original bivariate blending is revised in this work to better account animal models. The study data is extracted from...... the production trait evaluation of Nordic Red dairy cattle. Genotyped bulls with daughters are used as training animals, and genotyped bulls and producing cows as candidate animals. For simplicity, size of the data is chosen so that the full inverses of the mixed model equation coefficient matrices can...... be calculated. Model reliabilities by the single-step and the bivariate blending methods were higher than by animal model due to genomic information. Compared to the single-step method, the bivariate blending method reliability estimates were, in general, lower. Computationally bivariate blending method was...

  12. Asymptotics of bivariate generating functions with algebraic singularities

    Science.gov (United States)

    Greenwood, Torin

    Flajolet and Odlyzko (1990) derived asymptotic formulae the coefficients of a class of uni- variate generating functions with algebraic singularities. Gao and Richmond (1992) and Hwang (1996, 1998) extended these results to classes of multivariate generating functions, in both cases by reducing to the univariate case. Pemantle and Wilson (2013) outlined new multivariate ana- lytic techniques and used them to analyze the coefficients of rational generating functions. After overviewing these methods, we use them to find asymptotic formulae for the coefficients of a broad class of bivariate generating functions with algebraic singularities. Beginning with the Cauchy integral formula, we explicity deform the contour of integration so that it hugs a set of critical points. The asymptotic contribution to the integral comes from analyzing the integrand near these points, leading to explicit asymptotic formulae. Next, we use this formula to analyze an example from current research. In the following chapter, we apply multivariate analytic techniques to quan- tum walks. Bressler and Pemantle (2007) found a (d + 1)-dimensional rational generating function whose coefficients described the amplitude of a particle at a position in the integer lattice after n steps. Here, the minimal critical points form a curve on the (d + 1)-dimensional unit torus. We find asymptotic formulae for the amplitude of a particle in a given position, normalized by the number of steps n, as n approaches infinity. Each critical point contributes to the asymptotics for a specific normalized position. Using Groebner bases in Maple again, we compute the explicit locations of peak amplitudes. In a scaling window of size the square root of n near the peaks, each amplitude is asymptotic to an Airy function.

  13. Univariate description and bivariate statistical inference: the first step delving into data.

    Science.gov (United States)

    Zhang, Zhongheng

    2016-03-01

    In observational studies, the first step is usually to explore data distribution and the baseline differences between groups. Data description includes their central tendency (e.g., mean, median, and mode) and dispersion (e.g., standard deviation, range, interquartile range). There are varieties of bivariate statistical inference methods such as Student's t-test, Mann-Whitney U test and Chi-square test, for normal, skews and categorical data, respectively. The article shows how to perform these analyses with R codes. Furthermore, I believe that the automation of the whole workflow is of paramount importance in that (I) it allows for others to repeat your results; (II) you can easily find out how you performed analysis during revision; (III) it spares data input by hand and is less error-prone; and (IV) when you correct your original dataset, the final result can be automatically corrected by executing the codes. Therefore, the process of making a publication quality table incorporating all abovementioned statistics and P values is provided, allowing readers to customize these codes to their own needs.

  14. Block Based Bivariate Blending Rational Interpolation via Symmetric Branched Continued Fractions

    Institute of Scientific and Technical Information of China (English)

    Qianjin Zhao; Jieqing Tan

    2007-01-01

    This paper constructs a new kind of block based bivariate blending rational interpolation via symmetric branched continued fractions. The construction process may be outlined as follows. The first step is to divide the original set of support points into some subsets (blocks). Then construct each block by using symmetric branched continued fraction.Finally assemble these blocks by Newton's method to shape the whole interpolation scheme.Our new method offers many flexible bivariate blending rational interpolation schemes which include the classical bivariate Newton's polynomial interpolation and symmetric branched continued fraction interpolation as its special cases. The block based bivariate blending rational interpolation is in fact a kind of tradeoff between the purely linear interpolation and the purely nonlinear interpolation. Finally,numerical examples are given to show the effectiveness of the proposed method.

  15. Patch testing for food-associated allergies in orofacial granulomatosis.

    LENUS (Irish Health Repository)

    Fitzpatrick, Laura

    2011-01-01

    Food-associated allergies, especially to benzoates and cinnamon-related compounds, have been associated with orofacial granulomatosis and both standard and urticarial patch testing have been used to detect such allergies. Elimination diets have also been shown to be effective in some patients.

  16. Analysis of meteorological droughts for the Saskatchewan River Basin using univariate and bivariate approaches

    Science.gov (United States)

    Masud, M. B.; Khaliq, M. N.; Wheater, H. S.

    2015-03-01

    This study is focused on the Saskatchewan River Basin (SRB) that spans southern parts of Alberta, Saskatchewan and Manitoba, the three Prairie Provinces of Canada, where most of the country's agricultural activities are concentrated. The SRB is confronted with immense water-related challenges and is now one of the ten GEWEX (Global Energy and Water Exchanges) Regional Hydroclimate Projects in the world. In the past, various multi-year droughts have been observed in this part of Canada that impacted agriculture, energy and socio-economic sectors. Therefore, proper understanding of the spatial and temporal characteristics of historical droughts is important for many water resources planning and management related activities across the basin. In the study, observed gridded data of daily precipitation and temperature and conventional univariate and copula-based bivariate frequency analyses are used to characterize drought events in terms of drought severity and duration on the basis of two drought indices, the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI). Within the framework of univariate and bivariate analyses, drought risk indicators are developed and mapped across the SRB to delineate the most vulnerable parts of the basin. Based on the results obtained, southern parts of the SRB (i.e., western part of the South Saskatchewan River, Seven Persons Creek and Bigstick Lake watersheds) are associated with a higher drought risk, while moderate risk is noted for the North Saskatchewan River (except its eastern parts), Red Deer River, Oldman River, Bow River, Sounding Creek, Carrot River and Battle River watersheds. Lower drought risk is found for the areas surrounding the Saskatchewan-Manitoba border (particularly, the Saskatchewan River watershed). It is also found that the areas characterized with higher drought severity are also associated with higher drought duration. A comparison of SPI- and SPEI

  17. Dyadic Bivariate Fourier Multipliers for Multi-Wavelets in L2(R2)

    Institute of Scientific and Technical Information of China (English)

    Zhongyan Li∗; Xiaodi Xu

    2015-01-01

    The single 2 dilation orthogonal wavelet multipliers in one dimensional case and single A-dilation (where A is any expansive matrix with integer entries and|detA|=2) wavelet multipliers in high dimensional case were completely characterized by the Wutam Consortium (1998) and Z. Y. Li, et al. (2010). But there exist no more results on orthogonal multivariate wavelet matrix multipliers corresponding integer expansive dilation matrix with the absolute value of determinant not 2 in L2(R2). In this paper, we choose as the dilation matrix and consider the 2I2-dilation orthogonal multivariate wavelet Y={y1,y2,y3}, (which is called a dyadic bivariate wavelet) multipliers. We call the 3×3 matrix-valued function A(s)=[ fi,j(s)]3×3, where fi,j are measurable functions, a dyadic bivariate matrix Fourier wavelet multiplier if the inverse Fourier transform of A(s)(cy1(s),cy2(s),cy3(s))⊤ = ( b g1(s), b g2(s), b g3(s))⊤ is a dyadic bivariate wavelet whenever (y1,y2,y3) is any dyadic bivariate wavelet. We give some conditions for dyadic matrix bivariate wavelet multipliers. The results extended that of Z. Y. Li and X. L. Shi (2011). As an application, we construct some useful dyadic bivariate wavelets by using dyadic Fourier matrix wavelet multipliers and use them to image denoising.

  18. A stochastic model for the analysis of bivariate longitudinal AIDS data.

    Science.gov (United States)

    Sy, J P; Taylor, J M; Cumberland, W G

    1997-06-01

    We present a model for multivariate repeated measures that incorporates random effects, correlated stochastic processes, and measurement errors. The model is a multivariate generalization of the model for univariate longitudinal data given by Taylor, Cumberland, and Sy (1994, Journal of the American Statistical Association 89, 727-736). The stochastic process used in this paper is the multivariate integrated Ornstein-Uhlenbeck (OU) process, which includes Brownian motion and a random effects model as special limiting cases. This process is an underlying continuous-time autoregressive order [AR(1)] process for the derivatives of the multivariate observations. The model allows unequally spaced observations and missing values for some of the variables. We analyze CD4 T-cell and beta-2-microglobulin measurements of the seroconverters at multiple time points from the Los Angeles section of the Multicenter AIDS Cohort Study. The model allows us to investigate the relationship between CD4 and beta-2-microglobulin through the correlations between their random effects and their serial correlation. The data suggest that CD4 and beta-2-microglobulin follow a bivariate Brownian motion process. The fit of the model implies that an increase in beta-2-microglobulin is associated with a decrease in future CD4 but not vice versa, agreeing with immunologic postulates about the relationship between these two variables.

  19. Functional imaging of implicit marijuana associations during performance on an Implicit Association Test (IAT)

    NARCIS (Netherlands)

    Ames, S.L.; Grenard, J.L.; Stacy, A.W.; Xiao, L.; He, Q.; Wong, S.W; Xue, G.; Wiers, R.W.; Bechara, A.

    2013-01-01

    This research evaluated the neural correlates of implicit associative memory processes (habit-based processes) through the imaging (fMRI) of a marijuana Implicit Association Test. Drug-related associative memory effects have been shown to consistently predict level of drug use. To observe difference

  20. Function of cancer associated genes revealed by modern univariate and multivariate association tests.

    Directory of Open Access Journals (Sweden)

    Malka Gorfine

    Full Text Available Copy number variation (CNV plays a role in pathogenesis of many human diseases, especially cancer. Several whole genome CNV association studies have been performed for the purpose of identifying cancer associated CNVs. Here we undertook a novel approach to whole genome CNV analysis, with the goal being identification of associations between CNV of different genes (CNV-CNV across 60 human cancer cell lines. We hypothesize that these associations point to the roles of the associated genes in cancer, and can be indicators of their position in gene networks of cancer-driving processes. Recent studies show that gene associations are often non-linear and non-monotone. In order to obtain a more complete picture of all CNV associations, we performed omnibus univariate analysis by utilizing dCov, MIC, and HHG association tests, which are capable of detecting any type of association, including non-monotone relationships. For comparison we used Spearman and Pearson association tests, which detect only linear or monotone relationships. Application of dCov, MIC and HHG tests resulted in identification of twice as many associations compared to those found by Spearman and Pearson alone. Interestingly, most of the new associations were detected by the HHG test. Next, we utilized dCov's and HHG's ability to perform multivariate analysis. We tested for association between genes of unknown function and known cancer-related pathways. Our results indicate that multivariate analysis is much more effective than univariate analysis for the purpose of ascribing biological roles to genes of unknown function. We conclude that a combination of multivariate and univariate omnibus association tests can reveal significant information about gene networks of disease-driving processes. These methods can be applied to any large gene or pathway dataset, allowing more comprehensive analysis of biological processes.

  1. Motivating Students' Learning Using Word Association Test and Concept Maps

    Directory of Open Access Journals (Sweden)

    Z. Kostova

    2010-06-01

    Full Text Available The paper presents the effect of a free word association test, content analysis and concept mapping on students’ achievements in human biology. The free word association test was used for revealing the scientific conceptual structures of 8th grade and 12th grade students, around a stimulus word – human being – and for motivating them to study human biology. The stimulus word retrieved a cluster of associations most of which were based on science education and experience. Associations with the stimulus word were analyzed and classified according to predetermined criteria and structured by means of a concept map. The stimulus word ‘human being’ was quantitatively assessed in order to find out the balance between the associations with its different aspects. On the basis of the results some connections between biology and other sciences studying the human being, were worked out. Each new topic in human biology was studied by using content analysis of the textbook and concept mapping as study tools and thus maintaining students’ motivation. Achievements of students were assessed by means of tests, observation and concept maps evaluation. The obtained data was also valuable in clarifying the complex nature of the human being, and confirming the statement that biology cannot answer all questions, concerning human nature. Inferences were made about the word association test combined with content analysis and concept map construction as an educational strategy.

  2. Association testing strategy for data from dense marker panels.

    Directory of Open Access Journals (Sweden)

    Donghyung Lee

    Full Text Available Genome wide association studies have been usually analyzed in a univariate manner. The commonly used univariate tests have one degree of freedom and assume an additive mode of inheritance. The experiment-wise significance of these univariate statistics is obtained by adjusting for multiple testing. Next generation sequencing studies, which assay 10-20 million variants, are beginning to come online. For these studies, the strategy of additive univariate testing and multiple testing adjustment is likely to result in a loss of power due to (1 the substantial multiple testing burden and (2 the possibility of a non-additive causal mode of inheritance. To reduce the power loss we propose: a new method (1 to summarize in a single statistic the strength of the association signals coming from all not-very-rare variants in a linkage disequilibrium block and (2 to incorporate, in any linkage disequilibrium block statistic, the strength of the association signals under multiple modes of inheritance. The proposed linkage disequilibrium block test consists of the sum of squares of nominally significant univariate statistics. We compare the performance of this method to the performance of existing linkage disequilibrium block/gene-based methods. Simulations show that (1 extending methods to combine testing for multiple modes of inheritance leads to substantial power gains, especially for a recessive mode of inheritance, and (2 the proposed method has a good overall performance. Based on simulation results, we provide practical advice on choosing suitable methods for applied analyses.

  3. Statistical tests for associations between two directed acyclic graphs.

    Directory of Open Access Journals (Sweden)

    Robert Hoehndorf

    Full Text Available Biological data, and particularly annotation data, are increasingly being represented in directed acyclic graphs (DAGs. However, while relevant biological information is implicit in the links between multiple domains, annotations from these different domains are usually represented in distinct, unconnected DAGs, making links between the domains represented difficult to determine. We develop a novel family of general statistical tests for the discovery of strong associations between two directed acyclic graphs. Our method takes the topology of the input graphs and the specificity and relevance of associations between nodes into consideration. We apply our method to the extraction of associations between biomedical ontologies in an extensive use-case. Through a manual and an automatic evaluation, we show that our tests discover biologically relevant relations. The suite of statistical tests we develop for this purpose is implemented and freely available for download.

  4. Generalization of Rare Variant Association Tests for Longitudinal Family Studies.

    Science.gov (United States)

    Chien, Li-Chu; Hsu, Fang-Chi; Bowden, Donald W; Chiu, Yen-Feng

    2016-02-01

    Given the functional relevance of many rare variants, their identification is frequently critical for dissecting disease etiology. Functional variants are likely to be aggregated in family studies enriched with affected members, and this aggregation increases the statistical power to detect rare variants associated with a trait of interest. Longitudinal family studies provide additional information for identifying genetic and environmental factors associated with disease over time. However, methods to analyze rare variants in longitudinal family data remain fairly limited. These methods should be capable of accounting for different sources of correlations and handling large amounts of sequencing data efficiently. To identify rare variants associated with a phenotype in longitudinal family studies, we extended pedigree-based burden (BT) and kernel (KS) association tests to genetic longitudinal studies. Generalized estimating equation (GEE) approaches were used to generalize the pedigree-based BT and KS to multiple correlated phenotypes under the generalized linear model framework, adjusting for fixed effects of confounding factors. These tests accounted for complex correlations between repeated measures of the same phenotype (serial correlations) and between individuals in the same family (familial correlations). We conducted comprehensive simulation studies to compare the proposed tests with mixed-effects models and marginal models, using GEEs under various configurations. When the proposed tests were applied to data from the Diabetes Heart Study, we found exome variants of POMGNT1 and JAK1 genes were associated with type 2 diabetes.

  5. Diagnostic performance of des-γ-carboxy prothrombin (DCP) for hepatocellular carcinoma: a bivariate meta-analysis.

    Science.gov (United States)

    Gao, P; Li, M; Tian, Q B; Liu, Dian-Wu

    2012-01-01

    Serum markers are needed to be developed to specifically diagnose Hepatocellular carcinoma (HCC). Des-γ-carboxy prothrombin (DCP) is a promising tool with limited expense and widely accessibility, but the reported results have been controversial. In order to review the performance of DCP for the diagnosis of HCC, the meta-analysis was performed. After a systematic review of relevant studies, the sensitivity, specificity, positive and negative likelihood ratios (PLR and NLR, respectively) were pooled using a bivariate meta-analysis. Potential between-study heterogeneity was explored by meta-regression model. The post-test probability and the likelihood ratio scattergram to evaluate clinical usefulness were calculated. Based on literature review of 20 publications, the overall sensitivity, specificity, PLR and NLR of DCP for the detection of HCC were 67% (95%CI, 58%-74%), 92% (95%CI, 88%-94%), 7.9 (95%CI, 5.6-11.2) and 0.36 (95%CI, 0.29-0.46), respectively. The area under the bivariate summary receiving operating characteristics curve was 0.89 (95%CI, 0.85-0.92). Significant heterogeneity was present. In conclusion, the major role of DCP is the moderate confirmation of HCC. More prospective studies of DCP are needed in future.

  6. Multiply-Constrained Semantic Search in the Remote Associates Test

    Science.gov (United States)

    Smith, Kevin A.; Huber, David E.; Vul, Edward

    2013-01-01

    Many important problems require consideration of multiple constraints, such as choosing a job based on salary, location, and responsibilities. We used the Remote Associates Test to study how people solve such multiply-constrained problems by asking participants to make guesses as they came to mind. We evaluated how people generated these guesses…

  7. Statistics for quantifying heterogeneity in univariate and bivariate meta-analyses of binary data: the case of meta-analyses of diagnostic accuracy.

    Science.gov (United States)

    Zhou, Yan; Dendukuri, Nandini

    2014-07-20

    Heterogeneity in diagnostic meta-analyses is common because of the observational nature of diagnostic studies and the lack of standardization in the positivity criterion (cut-off value) for some tests. So far the unexplained heterogeneity across studies has been quantified by either using the I(2) statistic for a single parameter (i.e. either the sensitivity or the specificity) or visually examining the data in a receiver-operating characteristic space. In this paper, we derive improved I(2) statistics measuring heterogeneity for dichotomous outcomes, with a focus on diagnostic tests. We show that the currently used estimate of the 'typical' within-study variance proposed by Higgins and Thompson is not able to properly account for the variability of the within-study variance across studies for dichotomous variables. Therefore, when the between-study variance is large, the 'typical' within-study variance underestimates the expected within-study variance, and the corresponding I(2) is overestimated. We propose to use the expected value of the within-study variation in the construction of I(2) in cases of univariate and bivariate diagnostic meta-analyses. For bivariate diagnostic meta-analyses, we derive a bivariate version of I(2) that is able to account for the correlation between sensitivity and specificity. We illustrate the performance of these new estimators using simulated data as well as two real data sets.

  8. Reducing uncertainty in the selection of bi-variate distributions of flood peaks and volumes using copulas and hydrological process-based model selection

    Science.gov (United States)

    Szolgay, Jan; Gaál, Ladislav; Bacigál, Tomáš; Kohnová, Silvia; Blöschl, Günter

    2016-04-01

    Bi-variate distributions of flood peaks and flood event volumes are needed for a range of practical purposes including e.g. retention basin design and identifying extent and duration of flooding in flood hazard zones. However, the selection of the types of bi-variate distributions and estimating their parameters from observed peak-volume pairs are associated with far larger uncertainties compared to uni-variate distributions, since observed flood records of required length are rarely available. This poses a serious problem to reliable flood risk estimation in bi-variate design cases. The aim of this contribution was to shed light on the possibility of reducing uncertainties in the estimation of the dependence models/parameters from a regional perspective. The peak-volume relationships were modeled in terms of copulas. Flood events were classified according to their origin. In order to reduce the uncertainty in estimating flood risk, pooling and analyzing catchments of similar behavior according to flood process types was attempted. Most of the work reported in the literature so far did not direct the multivariate analysis toward discriminating certain types of models regionally according to specific runoff generation processes. Specifically, the contribution addresses these problems: - Are the peak-volume relationships of different flood types for a given catchment similar? - Are the peak-volume dependence structures between catchments in a larger region for given flood types similar? - Are some copula types more suitable for given flood process types and does this have consequences for reliable risk estimation? The target region is located in the northern parts of Austria, and consists of 72 small and mid-sized catchments. Instead of the traditional approach that deals with annual maximum floods, the current analysis includes all independent flood events in the region. 24 872 flood events from the period 1976-2007 were identified, and classified as synoptic, flash

  9. An Adaptive Genetic Association Test Using Double Kernel Machines.

    Science.gov (United States)

    Zhan, Xiang; Epstein, Michael P; Ghosh, Debashis

    2015-10-01

    Recently, gene set-based approaches have become very popular in gene expression profiling studies for assessing how genetic variants are related to disease outcomes. Since most genes are not differentially expressed, existing pathway tests considering all genes within a pathway suffer from considerable noise and power loss. Moreover, for a differentially expressed pathway, it is of interest to select important genes that drive the effect of the pathway. In this article, we propose an adaptive association test using double kernel machines (DKM), which can both select important genes within the pathway as well as test for the overall genetic pathway effect. This DKM procedure first uses the garrote kernel machines (GKM) test for the purposes of subset selection and then the least squares kernel machine (LSKM) test for testing the effect of the subset of genes. An appealing feature of the kernel machine framework is that it can provide a flexible and unified method for multi-dimensional modeling of the genetic pathway effect allowing for both parametric and nonparametric components. This DKM approach is illustrated with application to simulated data as well as to data from a neuroimaging genetics study.

  10. Copula-Based Bivariate Flood Frequency Analysis in a Changing Climate-A Case Study in the Huai River Basin, China

    Institute of Scientific and Technical Information of China (English)

    Kai Duan; Yadong Mei; Liping Zhang

    2016-01-01

    ABSTRACT:Copula-based bivariate frequency analysis can be used to investigate the changes in flood characteristics in the Huai River Basin that could be caused by climate change. The univariate distribu-tions of historical flood peak, maximum 3-day and 7-day volumes in 1961–2000 and future values in 2061–2100 projected from two GCMs (CSIRO-MK3.5 and CCCma-CGCM3.1) under A2, A1B and B1 emission scenarios are analyzed and compared. Then, bivariate distributions of peaks and volumes are constructed based on the copula method and possible changes in joint return periods are characterized. Results indicate that the Clayton copula is more appropriate for historical and CCCma-CGCM3.1 simu-lating flood variables, while that of Frank and Gumbel are better fitted to CSIRO-MK3.5 simulations. The variations of univariate and bivariate return periods reveal that flood characteristics may be more sensi-tive to different GCMs than different emission scenarios. Between the two GCMs, CSIRO-MK3.5 evi-dently predicts much more severe flood conditions in future, especially under B1 scenario, whereas CCCma-CGCM3.1 generally suggests contrary changing signals. This study corroborates that copulas can serve as a viable and flexible tool to connect univariate marginal distributions of flood variables and quantify the associated risks, which may provide useful information for risk-based flood control.

  11. Measurement of implicit associations between emotional states and computer errors using the implicit association test

    Directory of Open Access Journals (Sweden)

    Maricutoiu, Laurentiu P.

    2011-12-01

    Full Text Available Previous research identified two main emotional outcomes of computer error: anxiety and frustration. These emotions have been associated with low levels of performance in using a computer. The present research used innovative methodology for studying the relations between computer error messages, user anxiety and user frustration. We used the Implicit Association Test (IAT to measure automated associations between error messages and these two emotional outcomes. A sample of 80 participants completed two questionnaires and two IAT designs. Results indicated that user error messages are more strongly associated with anxiety, than with frustration. Personal characteristics such as emotional stability and English proficiency were significantly associated with the implicit anxiety measure, but not with the frustration measure. No significant relations were found between two measures of computer experience and the emotional measures. These results indicated that error related anxiety is associated with personal characteristics.

  12. The Pattern of Variation between Diarrhea and Malaria Coexistence with Corresponding Risk Factors in, Chikhwawa, Malawi: A Bivariate Multilevel Analysis

    Directory of Open Access Journals (Sweden)

    Salule Masangwi

    2015-07-01

    Full Text Available Developing countries face a huge burden of infectious diseases, a number of which co-exist. This paper estimates the pattern and variation of malaria and diarrhea coexistence in Chikhwawa, a district in Southern Malawi using bivariate multilevel modelling with Bayesian estimation. A probit link was employed to examine hierarchically built data from a survey of individuals (n = 6,727 nested within households (n = 1,380 nested within communities (n = 33. Results show significant malaria [ ] and diarrhea [ ] variations with a strong correlation between them [ ] at household level. There are significant malaria [ ] and diarrhea [   ] variations at community level but with a small correlation [ ] between them. There is also significant correlation between malaria and diarrhea at individual level [ 0.241]. These results suggest a close association between reported malaria-like illness and diarrheal illness especially at household and individual levels in Southern Malawi.

  13. On the construction of bivariate exponential distributions with an arbitrary correlation coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    In this paper we use a concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... the exponential random vectors....

  14. On the Construction of Bivariate Exponential Distributions with an Arbitrary Correlation Coefficient

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    2010-01-01

    In this article we use the concept of multivariate phase-type distributions to define a class of bivariate exponential distributions. This class has the following three appealing properties. Firstly, we may construct a pair of exponentially distributed random variables with any feasible correlation...... the exponential random vectors....

  15. A comparison of bivariate and univariate QTL mapping in livestock populations

    Directory of Open Access Journals (Sweden)

    Sorensen Daniel

    2003-11-01

    Full Text Available Abstract This study presents a multivariate, variance component-based QTL mapping model implemented via restricted maximum likelihood (REML. The method was applied to investigate bivariate and univariate QTL mapping analyses, using simulated data. Specifically, we report results on the statistical power to detect a QTL and on the precision of parameter estimates using univariate and bivariate approaches. The model and methodology were also applied to study the effectiveness of partitioning the overall genetic correlation between two traits into a component due to many genes of small effect, and one due to the QTL. It is shown that when the QTL has a pleiotropic effect on two traits, a bivariate analysis leads to a higher statistical power of detecting the QTL and to a more precise estimate of the QTL's map position, in particular in the case when the QTL has a small effect on the trait. The increase in power is most marked in cases where the contributions of the QTL and of the polygenic components to the genetic correlation have opposite signs. The bivariate REML analysis can successfully partition the two components contributing to the genetic correlation between traits.

  16. Identifying hidden common causes from bivariate time series: a method using recurrence plots.

    Science.gov (United States)

    Hirata, Yoshito; Aihara, Kazuyuki

    2010-01-01

    We propose a method for inferring the existence of hidden common causes from observations of bivariate time series. We detect related time series by excessive simultaneous recurrences in the corresponding recurrence plots. We also use a noncoverage property of a recurrence plot by the other to deny the existence of a directional coupling. We apply the proposed method to real wind data.

  17. A simple approximation to the bivariate normal distribution with large correlation coefficient

    NARCIS (Netherlands)

    Albers, Willem; Kallenberg, Wilbert C.M.

    1994-01-01

    The bivariate normal distribution function is approximated with emphasis on situations where the correlation coefficient is large. The high accuracy of the approximation is illustrated by numerical examples. Moreover, exact upper and lower bounds are presented as well as asymptotic results on the er

  18. Characterizations of bivariate models using dynamic Kullbak-Leibler discrimination measures

    OpenAIRE

    Navarro, J.; S. M. Sunoj; Linu, M.N.

    2011-01-01

    Abstract In this paper the residual Kullback-Leibler discrimination information measure is extended to conditionally specified models. The extension is used to characterize some bivariate distributions. These distributions are also characterized in terms of proportional hazard rate models and weighted distributions. Moreover, we also obtain some bounds for this dynamic discrimination function by using the likelihood ratio order and some preceding results. correspondence: ...

  19. Representing Topography with Second-Degree Bivariate Polynomial Functions Fitted by Least Squares.

    Science.gov (United States)

    Neuman, Arthur Edward

    1987-01-01

    There is a need for abstracting topography other than for mapping purposes. The method employed should be simple and available to non-specialists, thereby ruling out spline representations. Generalizing from univariate first-degree least squares and from multiple regression, this article introduces bivariate polynomial functions fitted by least…

  20. General Framework for Meta-Analysis of Haplotype Association Tests.

    Science.gov (United States)

    Wang, Shuai; Zhao, Jing Hua; An, Ping; Guo, Xiuqing; Jensen, Richard A; Marten, Jonathan; Huffman, Jennifer E; Meidtner, Karina; Boeing, Heiner; Campbell, Archie; Rice, Kenneth M; Scott, Robert A; Yao, Jie; Schulze, Matthias B; Wareham, Nicholas J; Borecki, Ingrid B; Province, Michael A; Rotter, Jerome I; Hayward, Caroline; Goodarzi, Mark O; Meigs, James B; Dupuis, Josée

    2016-04-01

    For complex traits, most associated single nucleotide variants (SNV) discovered to date have a small effect, and detection of association is only possible with large sample sizes. Because of patient confidentiality concerns, it is often not possible to pool genetic data from multiple cohorts, and meta-analysis has emerged as the method of choice to combine results from multiple studies. Many meta-analysis methods are available for single SNV analyses. As new approaches allow the capture of low frequency and rare genetic variation, it is of interest to jointly consider multiple variants to improve power. However, for the analysis of haplotypes formed by multiple SNVs, meta-analysis remains a challenge, because different haplotypes may be observed across studies. We propose a two-stage meta-analysis approach to combine haplotype analysis results. In the first stage, each cohort estimate haplotype effect sizes in a regression framework, accounting for relatedness among observations if appropriate. For the second stage, we use a multivariate generalized least square meta-analysis approach to combine haplotype effect estimates from multiple cohorts. Haplotype-specific association tests and a global test of independence between haplotypes and traits are obtained within our framework. We demonstrate through simulation studies that we control the type-I error rate, and our approach is more powerful than inverse variance weighted meta-analysis of single SNV analysis when haplotype effects are present. We replicate a published haplotype association between fasting glucose-associated locus (G6PC2) and fasting glucose in seven studies from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium and we provide more precise haplotype effect estimates.

  1. Meta-analysis of studies with bivariate binary outcomes: a marginal beta-binomial model approach.

    Science.gov (United States)

    Chen, Yong; Hong, Chuan; Ning, Yang; Su, Xiao

    2016-01-15

    When conducting a meta-analysis of studies with bivariate binary outcomes, challenges arise when the within-study correlation and between-study heterogeneity should be taken into account. In this paper, we propose a marginal beta-binomial model for the meta-analysis of studies with binary outcomes. This model is based on the composite likelihood approach and has several attractive features compared with the existing models such as bivariate generalized linear mixed model (Chu and Cole, 2006) and Sarmanov beta-binomial model (Chen et al., 2012). The advantages of the proposed marginal model include modeling the probabilities in the original scale, not requiring any transformation of probabilities or any link function, having closed-form expression of likelihood function, and no constraints on the correlation parameter. More importantly, because the marginal beta-binomial model is only based on the marginal distributions, it does not suffer from potential misspecification of the joint distribution of bivariate study-specific probabilities. Such misspecification is difficult to detect and can lead to biased inference using currents methods. We compare the performance of the marginal beta-binomial model with the bivariate generalized linear mixed model and the Sarmanov beta-binomial model by simulation studies. Interestingly, the results show that the marginal beta-binomial model performs better than the Sarmanov beta-binomial model, whether or not the true model is Sarmanov beta-binomial, and the marginal beta-binomial model is more robust than the bivariate generalized linear mixed model under model misspecifications. Two meta-analyses of diagnostic accuracy studies and a meta-analysis of case-control studies are conducted for illustration.

  2. An evolutionary framework for association testing in resequencing studies.

    Directory of Open Access Journals (Sweden)

    C Ryan King

    2010-11-01

    Full Text Available Sequencing technologies are becoming cheap enough to apply to large numbers of study participants and promise to provide new insights into human phenotypes by bringing to light rare and previously unknown genetic variants. We develop a new framework for the analysis of sequence data that incorporates all of the major features of previously proposed approaches, including those focused on allele counts and allele burden, but is both more general and more powerful. We harness population genetic theory to provide prior information on effect sizes and to create a pooling strategy for information from rare variants. Our method, EMMPAT (Evolutionary Mixed Model for Pooled Association Testing, generates a single test per gene (substantially reducing multiple testing concerns, facilitates graphical summaries, and improves the interpretation of results by allowing calculation of attributable variance. Simulations show that, relative to previously used approaches, our method increases the power to detect genes that affect phenotype when natural selection has kept alleles with large effect sizes rare. We demonstrate our approach on a population-based re-sequencing study of association between serum triglycerides and variation in ANGPTL4.

  3. A Bivariate Mixed Distribution with a Heavy-tailed Component and its Application to Single-site Daily Rainfall Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chao ..; Singh, Vijay P.; Mishra, Ashok K.

    2013-02-06

    This paper presents an improved brivariate mixed distribution, which is capable of modeling the dependence of daily rainfall from two distinct sources (e.g., rainfall from two stations, two consecutive days, or two instruments such as satellite and rain gauge). The distribution couples an existing framework for building a bivariate mixed distribution, the theory of copulae and a hybrid marginal distribution. Contributions of the improved distribution are twofold. One is the appropriate selection of the bivariate dependence structure from a wider admissible choice (10 candidate copula families). The other is the introduction of a marginal distribution capable of better representing low to moderate values as well as extremes of daily rainfall. Among several applications of the improved distribution, particularly presented here is its utility for single-site daily rainfall simulation. Rather than simulating rainfall occurrences and amounts separately, the developed generator unifies the two processes by generalizing daily rainfall as a Markov process with autocorrelation described by the improved bivariate mixed distribution. The generator is first tested on a sample station in Texas. Results reveal that the simulated and observed sequences are in good agreement with respect to essential characteristics. Then, extensive simulation experiments are carried out to compare the developed generator with three other alternative models: the conventional two-state Markov chain generator, the transition probability matrix model and the semi-parametric Markov chain model with kernel density estimation for rainfall amounts. Analyses establish that overall the developed generator is capable of reproducing characteristics of historical extreme rainfall events and is apt at extrapolating rare values beyond the upper range of available observed data. Moreover, it automatically captures the persistence of rainfall amounts on consecutive wet days in a relatively natural and easy way

  4. Measuring early or late dependence for bivariate lifetimes of twins

    DEFF Research Database (Denmark)

    Scheike, Thomas; Holst, Klaus K; Hjelmborg, Jacob B

    2015-01-01

    We consider data from the Danish twin registry and aim to study in detail how lifetimes for twin-pairs are correlated. We consider models where we specify the marginals using a regression structure, here Cox's regression model or the additive hazards model. The best known such model is the Clayton...... procedures are applied to Danish twin data to describe dependence in the lifetimes of the twins. Here we show that the early deaths are more correlated than the later deaths, and by comparing MZ and DZ associations we suggest that early deaths might be more driven by genetic factors. This conclusion requires...... models that are able to look at more local dependence measures. We further show that the dependence differs for MZ and DZ twins and appears to be the same for males and females, and that there are indications that the dependence increases over calendar time....

  5. Estimating twin concordance for bivariate competing risks twin data

    DEFF Research Database (Denmark)

    Scheike, Thomas Harder; Holst, Klaus Kähler; von Bornemann Hjelmborg, Jacob

    2014-01-01

    For twin time-to-event data, we consider different concordance probabilities, such as the casewise concordance that are routinely computed as a measure of the lifetime dependence/correlation for specific diseases. The concordance probability here is the probability that both twins have experienced...... over time, and covariates may be further influential on the marginal risk and dependence structure. We establish the estimators large sample properties and suggest various tests, for example, for inferring familial influence. The method is demonstrated and motivated by specific twin data on cancer...... the event of interest. Under the assumption that both twins are censored at the same time, we show how to estimate this probability in the presence of right censoring, and as a consequence, we can then estimate the casewise twin concordance. In addition, we can model the magnitude of within pair dependence...

  6. Extending the Implicit Association Test (IAT): Assessing Consumer Attitudes Based on Multi-Dimensional Implicit Associations

    NARCIS (Netherlands)

    Gattol, V.; Sääksjärvi, M.; Carbon, C.-C.

    2011-01-01

    Background: The authors present a procedural extension of the popular Implicit Association Test (IAT; [1]) that allows for indirect measurement of attitudes on multiple dimensions (e.g., safe–unsafe; young–old; innovative–conventional, etc.) rather than on a single evaluative dimension only (e.g., g

  7. Estimating twin concordance for bivariate competing risks twin data.

    Science.gov (United States)

    Scheike, Thomas H; Holst, Klaus K; Hjelmborg, Jacob B

    2014-03-30

    For twin time-to-event data, we consider different concordance probabilities, such as the casewise concordance that are routinely computed as a measure of the lifetime dependence/correlation for specific diseases. The concordance probability here is the probability that both twins have experienced the event of interest. Under the assumption that both twins are censored at the same time, we show how to estimate this probability in the presence of right censoring, and as a consequence, we can then estimate the casewise twin concordance. In addition, we can model the magnitude of within pair dependence over time, and covariates may be further influential on the marginal risk and dependence structure. We establish the estimators large sample properties and suggest various tests, for example, for inferring familial influence. The method is demonstrated and motivated by specific twin data on cancer events with the competing risk death. We thus aim to quantify the degree of dependence through the casewise concordance function and show a significant genetic component.

  8. Identifying barriers to HIV testing: personal and contextual factors associated with late HIV testing.

    Science.gov (United States)

    Schwarcz, Sandra; Richards, T Anne; Frank, Heidi; Wenzel, Conrad; Hsu, Ling Chin; Chin, Chi-Sheng Jennie; Murphy, Jessie; Dilley, James

    2011-07-01

    Late diagnosis of HIV is associated with increased morbidity, mortality, and health care costs. Despite the availability of HIV testing, persons continue to test late in the course of HIV infection. We used the HIV/AIDS case registry of San Francisco Department of Public Health to identify and recruit 41 persons who developed AIDS within 12 months of their HIV diagnosis to participate in a qualitative and quantitative interview regarding late diagnosis of HIV. Thirty-one of the participants were diagnosed with HIV because of symptomatic disease and 50% of the participants were diagnosed with HIV and AIDS concurrently. Half of the subjects had not been tested for HIV prior to diagnosis. Fear was the most frequently cited barrier to testing. Other barriers included being unaware of improved HIV treatment, free/low cost care, and risk for HIV. Recommendations for health care providers to increase early diagnosis of HIV include routine ascertainment of HIV risk behaviors and testing histories, stronger recommendations for patients to be tested, and incorporating testing into routine medical care. Public health messages to increase testing include publicizing that (1) effective, tolerable, and low cost/free care for HIV is readily available, (2) early diagnosis of HIV improves health outcomes, (3) HIV can be transmitted to persons who engage in unprotected oral and insertive anal sex and unprotected receptive anal intercourse without ejaculation and from HIV-infected persons whose infection is well-controlled with antiretroviral therapy, (4) persons who may be infected based upon these behaviors should be tested following exposure, (5) HIV testing information will be kept private, and (6) encouraging friends and family to get HIV tested is beneficial.

  9. Exploratory Causal Analysis in Bivariate Time Series Data

    Science.gov (United States)

    McCracken, James M.

    sets, but little research exists of how these tools compare to each other in practice. This work introduces and defines exploratory causal analysis (ECA) to address this issue along with the concept of data causality in the taxonomy of causal studies introduced in this work. The motivation is to provide a framework for exploring potential causal structures in time series data sets. ECA is used on several synthetic and empirical data sets, and it is found that all of the tested time series causality tools agree with each other (and intuitive notions of causality) for many simple systems but can provide conflicting causal inferences for more complicated systems. It is proposed that such disagreements between different time series causality tools during ECA might provide deeper insight into the data than could be found otherwise.

  10. Disentangling recoding processes and evaluative associations in a gender attitude implicit association test among adult males.

    Science.gov (United States)

    Jin, Zheng

    2016-11-01

    The course of male development of implicit gender attitudes between young age (N = 30, age 17-26 years) and old age (N = 34, age 56-78 years) was investigated. The findings demonstrated that younger males had a stronger implicit preference for females relative to males than did older participants, shedding light on the nature of age differences in gender attitudes in regard to implicit measures. Although younger and older participants demonstrated different levels of gender bias on an implicit association test (IAT), the application of the ReAL model [Meissner, F., & Rothermund, K. (2013). Estimating the contributions of associations and recoding in the implicit association test: The ReAL model for the IAT. Journal of Personality and Social Psychology, 104(1), 45-69.] showed that evaluative associations of both female and male were activated at equivalent levels among both the young and old age groups, but younger males were more able to recode the female gender and a positive evaluation into common categories. Thus, the differences in attitudinal responses between younger and older males exaggerated the differences in the underlying evaluative associations with respect to gender and concealed the differences in recoding processes. These findings have important implications for the measurement and interpretation of implicit gender attitudes.

  11. A discrimination-association model for decomposing component processes of the implicit association test.

    Science.gov (United States)

    Stefanutti, Luca; Robusto, Egidio; Vianello, Michelangelo; Anselmi, Pasquale

    2013-06-01

    A formal model is proposed that decomposes the implicit association test (IAT) effect into three process components: stimuli discrimination, automatic association, and termination criterion. Both response accuracy and reaction time are considered. Four independent and parallel Poisson processes, one for each of the four label categories of the IAT, are assumed. The model parameters are the rate at which information accrues on the counter of each process and the amount of information that is needed before a response is given. The aim of this study is to present the model and an illustrative application in which the process components of a Coca-Pepsi IAT are decomposed.

  12. 二元二次函数逼近的存在性和局部性%The Existence and Local Behavior of the Bivariate Quadratic Function Approximation

    Institute of Scientific and Technical Information of China (English)

    郑成德

    2006-01-01

    This paper analysis the local behavior of the bivariate quadratic function approximation to a bivariate function which has a given power series expansion about the origin. It function and that this function is analytic in a neighborhood of the origin.

  13. Construct validity of the Big Five Implicit Association Test

    Directory of Open Access Journals (Sweden)

    Gaja Zager Kocjan

    2014-02-01

    Full Text Available Psychology has recently seen a noticeable increase in interest for implicit measures of attitudes and personality characteristics. The far most known implicit measure is the Implicit Association Test – IAT. We adapted this test in order to assess the Big Five personality dimensions (B5 IAT. We examined B5 IAT measurement characteristics on two samples. Based on the findings of the first sample (N = 62, improvements were made in the B5 IAT, to be tested again on another sample (N = 75. The two studies have shown similar results. The reliabilities of the personality dimensions measured with the B5 IAT failed to achieve a satisfactory level in most cases. The reason probably lies in a lower adequacy of certain stimuli and in the considerable length of the test procedure. The convergent validity of the B5 IAT with explicit measures of personality was low, which may be due to different structures underlying implicit and explicit measures. Results obtained on the first sample have shown that the correlations between IAT adjectives are adequately explained by five latent dimensions. However, these results should be interpreted with caution due to B5 IAT low reliabilities and small sample sizes. The second sample proved to be very unstable, thus the confirmatory factor analysis could not be conducted. Since this is the first attempt to adapt B5 IAT to Slovene language, it is hardly surprising that the results are not entirely consistent with the expectations. As implicit measures currently fail to meet relevant psychometric characteristics, they are not yet applicable in psychological practice. Nevertheless, they have great potential in exploring personality and individual differences, as they overcome many limitations of existing explicit measures.

  14. On the Bivariate Spectral Homotopy Analysis Method Approach for Solving Nonlinear Evolution Partial Differential Equations

    Directory of Open Access Journals (Sweden)

    S. S. Motsa

    2014-01-01

    Full Text Available This paper presents a new application of the homotopy analysis method (HAM for solving evolution equations described in terms of nonlinear partial differential equations (PDEs. The new approach, termed bivariate spectral homotopy analysis method (BISHAM, is based on the use of bivariate Lagrange interpolation in the so-called rule of solution expression of the HAM algorithm. The applicability of the new approach has been demonstrated by application on several examples of nonlinear evolution PDEs, namely, Fisher’s, Burgers-Fisher’s, Burger-Huxley’s, and Fitzhugh-Nagumo’s equations. Comparison with known exact results from literature has been used to confirm accuracy and effectiveness of the proposed method.

  15. Implicit associations in cybersex addiction: Adaption of an Implicit Association Test with pornographic pictures.

    Science.gov (United States)

    Snagowski, Jan; Wegmann, Elisa; Pekal, Jaro; Laier, Christian; Brand, Matthias

    2015-10-01

    Recent studies show similarities between cybersex addiction and substance dependencies and argue to classify cybersex addiction as a behavioral addiction. In substance dependency, implicit associations are known to play a crucial role, and such implicit associations have not been studied in cybersex addiction, so far. In this experimental study, 128 heterosexual male participants completed an Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) modified with pornographic pictures. Further, problematic sexual behavior, sensitivity towards sexual excitation, tendencies towards cybersex addiction, and subjective craving due to watching pornographic pictures were assessed. Results show positive relationships between implicit associations of pornographic pictures with positive emotions and tendencies towards cybersex addiction, problematic sexual behavior, sensitivity towards sexual excitation as well as subjective craving. Moreover, a moderated regression analysis revealed that individuals who reported high subjective craving and showed positive implicit associations of pornographic pictures with positive emotions, particularly tended towards cybersex addiction. The findings suggest a potential role of positive implicit associations with pornographic pictures in the development and maintenance of cybersex addiction. Moreover, the results of the current study are comparable to findings from substance dependency research and emphasize analogies between cybersex addiction and substance dependencies or other behavioral addictions.

  16. Bivariate linkage analysis of the insulin resistance syndrome phenotypes on chromosome 7q.

    Science.gov (United States)

    Lehman, Donna M; Arya, Rector; Blangero, John; Almasy, Laura; Puppala, Sobha; Dyer, Thomas D; Leach, Robin J; O'Connell, Peter; Stern, Michael P; Duggirala, Ravindranath

    2005-04-01

    Metabolic abnormalities of the insulin resistance syndrome (IRS) have been shown to aggregate in families and to exhibit trait-pair correlations, suggesting a common genetic component. A broad region on chromosome 7q has been implicated in several studies to contain loci that cosegregate with IRS-related traits. However, it is not clear whether such loci have any common genetic (pleiotropic) influences on the correlated traits. Also, it is not clear whether the chromosomal regions contain more than one locus influencing the IRS-related phenotypes. In this study we present evidence for linkage of five IRS-related traits [body mass index (BMI), waist circumference (WC), In split proinsulin (LSPI), In triglycerides (LTG), and high-density lipoprotein cholesterol (HDLC)] to a region at 7q11.23. Subsequently, to gain further insight into the genetic component(s) mapping to this region, we explored whether linkage of these traits is due to pleiotropic effects using a bivariate linkage analytical technique, which has been shown to localize susceptibility regions with precision. Four hundred forty individuals from 27 Mexican American families living in Texas were genotyped for 19 highly polymorphic markers on chromosome 7. Multipoint variance component linkage analysis was used to identify genetic location(s) influencing IRS-related traits of obesity (BMI and WC), dyslipidemia (LTG and HDLC), and insulin levels (LSPI); the analysis identified a broad chromosomal region spanning approximately 24 cM. To gain more precision in localization, we used a bivariate linkage approach for each trait pair. These analyses suggest localization of most of these bivariate traits to an approximately 6-cM region near marker D7S653 [7q11.23, 103-109 cM; a maximum bivariate LOD of 4.51 was found for the trait pair HDLC and LSPI (the LODeq score is 3.94)]. We observed evidence of pleiotropic effects in this region on obesity and insulin-related trait pairs.

  17. Technical note: Towards a continuous classification of climate using bivariate colour mapping

    Directory of Open Access Journals (Sweden)

    A. J. Teuling

    2011-06-01

    Full Text Available Climate is often defined in terms of discrete classes. Here I use bivariate colour mapping to show that the global distribution of Köppen-Geiger climate classes can largely be reproduced by combining the simple means of two key states of the climate system (i.e., air temperature and relative humidity. This allows for a classification that is not only continuous in space, but can be applied at and transferred between timescales ranging from minutes to decades.

  18. Technical note: Towards a continuous classification of climate using bivariate colour mapping

    Directory of Open Access Journals (Sweden)

    A. J. Teuling

    2011-10-01

    Full Text Available Climate is often defined in terms of discrete classes. Here I use bivariate colour mapping to show that the global distribution of Köppen-Geiger climate classes can largely be reproduced by combining the simple means of two key states of the climate system (i.e. air temperature and relative humidity. This allows for a classification that is not only continuous in space, but can be applied at and transferred between timescales ranging from days to decades.

  19. THE STRUCTURAL CHARACTERIZATION AND LOCALLY SUPPORTED BASES FOR BIVARIATE SUPER SPLINES

    Institute of Scientific and Technical Information of China (English)

    Zhi-qiang Xu; Ren-hong Wang

    2004-01-01

    Super splines are bivariate splines defined on triangulations, where the smoothness enforced at the vertices is larger than the smoothness enforced across the edges. In this paper, the smoothness conditions and conformality conditions for super splines are presented.Three locally supported super splines on type-1 triangulation are presented. Moreover, the criteria to select local bases is also given. By using local supported super spline function, avariation-diminishing operator is built. The approximation properties of the operator are also presented.

  20. THE BLOSSOM APPROACH TO THE DIMENSION OF THE BIVARIATE SPLINE SPACE

    Institute of Scientific and Technical Information of China (English)

    Yu-yu Feng; Zhi-bin Chen

    2000-01-01

    The dimension of the bivariate spline space S r n(Δ) may depend on geometric properties of triangulation Δ, in particular if n is not much bigger than r. In the paper, the blossom approach to the dimension count is outlined. It leads to the symbolic algorithm that gives the answer if a triangulation is singular or not. The approach is demonstrated on the case of Morgan-Scott partition and twice differentiable splines.

  1. A Spiking Neuron Model of Word Associations for the Remote Associates Test

    Science.gov (United States)

    Kajić, Ivana; Gosmann, Jan; Stewart, Terrence C.; Wennekers, Thomas; Eliasmith, Chris

    2017-01-01

    Generating associations is important for cognitive tasks including language acquisition and creative problem solving. It remains an open question how the brain represents and processes associations. The Remote Associates Test (RAT) is a task, originally used in creativity research, that is heavily dependent on generating associations in a search for the solutions to individual RAT problems. In this work we present a model that solves the test. Compared to earlier modeling work on the RAT, our hybrid (i.e., non-developmental) model is implemented in a spiking neural network by means of the Neural Engineering Framework (NEF), demonstrating that it is possible for spiking neurons to be organized to store the employed representations and to manipulate them. In particular, the model shows that distributed representations can support sophisticated linguistic processing. The model was validated on human behavioral data including the typical length of response sequences and similarity relationships in produced responses. These data suggest two cognitive processes that are involved in solving the RAT: one process generates potential responses and a second process filters the responses. PMID:28210234

  2. Simultaneous determination of Nifuroxazide and Drotaverine hydrochloride in pharmaceutical preparations by bivariate and multivariate spectral analysis

    Science.gov (United States)

    Metwally, Fadia H.

    2008-02-01

    The quantitative predictive abilities of the new and simple bivariate spectrophotometric method are compared with the results obtained by the use of multivariate calibration methods [the classical least squares (CLS), principle component regression (PCR) and partial least squares (PLS)], using the information contained in the absorption spectra of the appropriate solutions. Mixtures of the two drugs Nifuroxazide (NIF) and Drotaverine hydrochloride (DRO) were resolved by application of the bivariate method. The different chemometric approaches were applied also with previous optimization of the calibration matrix, as they are useful in simultaneous inclusion of many spectral wavelengths. The results found by application of the bivariate, CLS, PCR and PLS methods for the simultaneous determinations of mixtures of both components containing 2-12 μg ml -1 of NIF and 2-8 μg ml -1 of DRO are reported. Both approaches were satisfactorily applied to the simultaneous determination of NIF and DRO in pure form and in pharmaceutical formulation. The results were in accordance with those given by the EVA Pharma reference spectrophotometric method.

  3. Source apportionment advances using polar plots of bivariate correlation and regression statistics

    Science.gov (United States)

    Grange, Stuart K.; Lewis, Alastair C.; Carslaw, David C.

    2016-11-01

    This paper outlines the development of enhanced bivariate polar plots that allow the concentrations of two pollutants to be compared using pair-wise statistics for exploring the sources of atmospheric pollutants. The new method combines bivariate polar plots, which provide source characteristic information, with pair-wise statistics that provide information on how two pollutants are related to one another. The pair-wise statistics implemented include weighted Pearson correlation and slope from two linear regression methods. The development uses a Gaussian kernel to locally weight the statistical calculations on a wind speed-direction surface together with variable-scaling. Example applications of the enhanced polar plots are presented by using routine air quality data for two monitoring sites in London, United Kingdom for a single year (2013). The London examples demonstrate that the combination of bivariate polar plots, correlation, and regression techniques can offer considerable insight into air pollution source characteristics, which would be missed if only scatter plots and mean polar plots were used for analysis. Specifically, using correlation and slopes as pair-wise statistics, long-range transport processes were isolated and black carbon (BC) contributions to PM2.5 for a kerbside monitoring location were quantified. Wider applications and future advancements are also discussed.

  4. A Case Study of Bivariate Rainfall Frequency Analysis Using Copula in South Korea

    Science.gov (United States)

    Joo, K.; Shin, J.; Kim, W.; Heo, J.

    2011-12-01

    For a given rainfall event, it can be characterized into some properties such as rainfall depth (amount), duration, and intensity. By considering these factors simultaneously, the actual phenomenon of rainfall event can be explained better than univariate model. Using bivariate model, rainfall quantiles can be obtained for a given return period without any limitations of specific rainfall duration. For bivariate(depth and duration) frequency analysis, copula model was used in this study. Recently, copula model has been studied widely for hydrological field. And it is more flexible for marginal distribution than other conventional bivariate models. In this study, five weather stations are applied for frequency analysis from Korea Meteorological Administration (KMA) which are Seoul, Chuncheon, Gangneung, Wonju, and Chungju stations. These sites have 38 ~ 50 years of hourly precipitation data. Inter-event time definition is used for identification of rainfall events. And three copula models (Gumbel-Hougaard, Frank, and Joe) are applied in this study. Maximum pseudo-likelihood estimation method is used to estimate the parameter of copula (θ). The normal, generalized extreme value, Gumbel, 3-parameter gamma, and generalized logistic distributions are examined for marginal distribution. As a result, rainfall quantiles can be obtained for any rainfall durations for a given return period by calculating conditional probability. In addition, rainfall quantiles from copula models are compared to those from univariate model.

  5. Density Estimation for Protein Conformation Angles Using a Bivariate von Mises Distribution and Bayesian Nonparametrics.

    Science.gov (United States)

    Lennox, Kristin P; Dahl, David B; Vannucci, Marina; Tsai, Jerry W

    2009-06-01

    Interest in predicting protein backbone conformational angles has prompted the development of modeling and inference procedures for bivariate angular distributions. We present a Bayesian approach to density estimation for bivariate angular data that uses a Dirichlet process mixture model and a bivariate von Mises distribution. We derive the necessary full conditional distributions to fit the model, as well as the details for sampling from the posterior predictive distribution. We show how our density estimation method makes it possible to improve current approaches for protein structure prediction by comparing the performance of the so-called "whole" and "half" position distributions. Current methods in the field are based on whole position distributions, as density estimation for the half positions requires techniques, such as ours, that can provide good estimates for small datasets. With our method we are able to demonstrate that half position data provides a better approximation for the distribution of conformational angles at a given sequence position, therefore providing increased efficiency and accuracy in structure prediction.

  6. Galaxy And Mass Assembly (GAMA): Bivariate functions of H$\\alpha$ star forming galaxies

    CERN Document Server

    Gunawardhana, M L P; Taylor, E N; Bland-Hawthorn, J; Norberg, P; Baldry, I K; Loveday, J; Owers, M S; Wilkins, S M; Colless, M; Brown, M J I; Driver, S P; Alpaslan, M; Brough, S; Cluver, M; Croom, S; Kelvin, L; Lara-López, M A; Liske, J; López-Sánchez, A R; Robotham, A S G

    2014-01-01

    We present bivariate luminosity and stellar mass functions of H$\\alpha$ star forming galaxies drawn from the Galaxy And Mass Assembly (GAMA) survey. While optically deep spectroscopic observations of GAMA over a wide sky area enable the detection of a large number of $0.001<{SFR}_{H\\alpha}$ (M$_{\\odot}$ yr$^{-1}$)$<100$ galaxies, the requirement for an H$\\alpha$ detection in targets selected from an $r$-band magnitude limited survey leads to an incompleteness due to missing optically faint star forming galaxies. Using $z<0.1$ bivariate distributions as a reference we model the higher-$z$ distributions, thereby approximating a correction for the missing optically faint star forming galaxies to the local SFR and stellar mass densities. Furthermore, we obtain the $r$-band LFs and stellar mass functions of H$\\alpha$ star forming galaxies from the bivariate LFs. As our sample is selected on the basis of detected H$\\alpha$ emission, a direct tracer of on-going star formation, this sample represents a true ...

  7. Associated factors to urinary incontinence in women undergoing urodynamic testing

    Directory of Open Access Journals (Sweden)

    Juliana Cristina Pereira da Silva

    Full Text Available Abstract OBJECTIVE Analyzing factors associated with urinary incontinence (UI among women submitted to urodynamic testing. METHOD A cross-sectional study of 150 women attended at a urological center. Data were analyzed using univariate and multivariate statistics. RESULTS White women (79.3%, overweight (45.3%, menopausal (53.3%, who drink coffee (82.7%, sedentary (65.3%, who had vaginal birth (51.4%, with episiotomy (80%, and who underwent the Kristeller maneuver (69%. 60.7% had Urethral Hypermobility (UH. A statistical association was found between: weight change and UH (p = 0.024; menopause, Intrinsic Sphincter Deficiency (ISD and Detrusor Instability (DI (p = 0.001; gynecological surgery, ISD and DI (p = 0.014; hysterectomy and all types of UI (p = 0.040; physical activity and mixed UI (p = 0.014. CONCLUSION Interventions and guidance on preventing UI and strengthening pelvic muscles should be directed at women who present weight changes, who are sedentary menopausal women, and those who have undergone hysterectomy or other gynecological surgery. Studies on pelvic strengthening methods are needed in order to take into account the profile of the needs presented by women.

  8. Event-related potentials associated with Attention Network Test.

    Science.gov (United States)

    Neuhaus, Andres H; Urbanek, Carsten; Opgen-Rhein, Carolin; Hahn, Eric; Ta, Thi Minh Tam; Koehler, Simone; Gross, Melanie; Dettling, Michael

    2010-05-01

    Selective visual attention is thought to be comprised of distinct neuronal networks that serve different attentional functions. The Attention Network Test (ANT) has been introduced to allow for assessment of alerting, orienting, and response inhibition. Information on associated measures of neural processing during ANT is still scarce. We topographically analyzed top-down ANT effects on visual event-related potential morphology in 44 healthy participants. Significant reaction time effects were obtained for all attention networks. Posterior cue-locked target N1 amplitude was significantly increased during both alerting and orienting. P3 amplitude was significantly modulated at frontal and parietal leads as a function of inhibition. Our data suggests that attentional mechanisms of alerting and orienting are employed simultaneously at early stages of the visual processing stream to amplify perceptual discrimination and load onto the same ERP component. Fronto-parietal modulations of P3 amplitude seem to mirror both response inhibition and visual target detection and may be interesting markers for further studies.

  9. Filling in the gaps: using testing and restudy to promote associative learning.

    Science.gov (United States)

    Bulevich, John B; Thomas, Ayanna K; Parsow, Charles

    2016-10-01

    Although testing has been shown to potentiate subsequent learning [Izawa, C. (1966). Reinforcement-test sequences in paired-associate learning. Psychological Reports, 18, 879-919.], the mechanisms that influence this effect are not entirely understood. The present research examined the relationship between associative binding and test-potentiation effects. We hypothesised that test-potentiation effects would be most pronounced when participants could easily extract the relationship among word groupings. Towards that end, we compared three-word groupings, or triads, that were either semantically related or unrelated. Participants engaged in repeated study, repeated testing, or engaged in interpolated study and test prior to a final test. Final test performance was greatest for participants who engaged in interpolated study and test on related triads. The results support three primary conclusions: (1) testing aids in associative binding; (2) associative binding is facilitated by retrieval practice and restudy pairings; and (3) pre-existing associations facilitate test-potentiation effects.

  10. THEOREMS OF PEANO'S TYPE FOR BIVARIATE FUNCTIONS AND OPTIMAL RECOVERY OF LINEAR FUNCTIONALS

    Institute of Scientific and Technical Information of China (English)

    N.K. Dicheva

    2001-01-01

    The best recovery of a linear functional Lf , f =f (x,y), on thebasis of given linear functionals Ljf ,j=1,2, … ,N in a sense of Sard has been investigated, using analogy of Peano's theorem. The best recovery of a bivariate function by given scattered data has been obtained in a simple analytical form as a special case.CLC Number:O17 Document ID:AAuthor Resume:Natasha K. Dicheva ,e-mail: dichevan_fgs@uacg, acad. bg References:[1]Rudin,W. ,Principles of Mathematical Analysis,2ed. ,McGraw-Hill Book Co. ,New York,1964.[2]Rudin,W. ,Real and Complex Analysis,McGraw-Hill publishing Co. ,New York,1976.[3]Hewitt,E. and Stromberg,K. ,Real and Abstract Analysis,Springer-Verlag,New York,Berlin,1965.[4]Lusternik,L. and Sobolev,V. ,Elements of the Functional Analysis,Izd. Nauka,Moskva,1965 (in Russian).[5]Sard,A.,Integral Representation of Remainders Duke Math. J.,15(1948),333-345.[6]Sard,A. ,Linear Approximation,Amer. Math. Soc. ,Math. Surverys,9,1963.[7]Smolyak,S.A. ,On the optimal reconvery of Functions and Functionals of Them,Ph. D. Thesis,Moscow State University,1965.[8]Nielson,G.,Bivariate Spline Functions and the Approximation of Linear Functionals,Numer.Math.,21(1973),138-160.[9]Mansfield,L.E. ,Optimal Approximations and Error Bounds in Spaces of Bivariate Functions,J. Approx. Theory 5(1972),77-96.[10]Mansfield,L.E. ,On the Optimal Approximation of Linear Functionals in Spaces of Bivariate Functions,SIAM J. Numer. Anal ,8(1971),115-126.[11]Ritter,D. ,Two Dimensional Spline Functions and best Approximation of Linear Functionals,J. Approx. Theory,3(1970),352-368.[12]Laurent,P.J. ,Approximation et optimisation,Hermann,Paris,1972.[13]Bojanov,B. ,Hakopian,H.A. and Sahakian,A.A. ,Spline Functions and Multivariate Interpolations,Kluwer Academic Publishers,Dordrecht,1993.[14]Dicheve,N.K.,On the best Recovery of Linear Functional and its Applications,Boundary Elements XXI,eds. C.A. Brebbia and H. Power,WIT Press,Southampton,Boston,(1999),739-747.Manuscript Received

  11. Bivariate Drought Analysis Using Streamflow Reconstruction with Tree Ring Indices in the Sacramento Basin, California, USA

    Directory of Open Access Journals (Sweden)

    Jaewon Kwak

    2016-03-01

    Full Text Available Long-term streamflow data are vital for analysis of hydrological droughts. Using an artificial neural network (ANN model and nine tree-ring indices, this study reconstructed the annual streamflow of the Sacramento River for the period from 1560 to 1871. Using the reconstructed streamflow data, the copula method was used for bivariate drought analysis, deriving a hydrological drought return period plot for the Sacramento River basin. Results showed strong correlation among drought characteristics, and the drought with a 20-year return period (17.2 million acre-feet (MAF per year in the Sacramento River basin could be considered a critical level of drought for water shortages.

  12. Some Improved Estimators of Co-efficient of Variation from Bi-variate normal distribution: A Monte Carlo Comparison

    Directory of Open Access Journals (Sweden)

    Archana V

    2014-05-01

    Full Text Available Co-efficient of variation is a unitless measure of dispersion and is very frequently used in scientific investigations. This has motivated several researchers to propose estimators and tests concerning the co-efficient of variation of normal distribution(s. While proposing a class of estimators for the co-efficient of variation of a finite population, Tripathi et al., (2002 suggested that the estimator of co-efficient of variation of a finite population can also be used as an estimator of C.V for any distribution when the sampling design is SRSWR. This has motivated us to propose 28 estimators of finite population co-efficient of variation as estimators of co-efficient of variation of one component of a bivariate normal distribution when prior information is available regarding the second component. Cramer Rao type lower bound is derived to the mean square error of these estimators. Extensive simulation is carried out to compare these estimators. The results indicate that out of these 28 estimators, eight estimators have larger relative efficiency compared to the sample co-efficient of variation. The asymptotic mean square errors of the best estimators are derived to the order of  for the benefit of users of co-efficient of variation.

  13. A bivariate optimal replacement policy with cumulative repair cost limit under cumulative damage model

    Indian Academy of Sciences (India)

    MIN-T SAI LAI; SHIH-CHIH CHEN

    2016-05-01

    In this paper, a bivariate replacement policy (n, T) for a cumulative shock damage process is presented that included the concept of cumulative repair cost limit. The arrival shocks can be divided into two kinds of shocks. Each type-I shock causes a random amount of damage and these damages are additive. When the total damage exceeds a failure level, the system goes into serious failure. Type-II shock causes the system into minor failure and such a failure can be corrected by minimal repair. When a minor failure occurs, the repaircost will be evaluated and minimal repair is executed if the accumulated repair cost is less than a predetermined limit L. The system is replaced at scheduled time T, at n-th minor failure, or at serious failure. The long-term expected cost per unit time is derived using the expected costs as the optimality criterion. The minimum-cost policy is derived, and existence and uniqueness of the optimal n* and T* are proved. This bivariate optimal replacement policy (n, T) is showed to be better than the optimal T* and the optimal n* policy.

  14. A method of moments to estimate bivariate survival functions: the copula approach

    Directory of Open Access Journals (Sweden)

    Silvia Angela Osmetti

    2013-05-01

    Full Text Available In this paper we discuss the problem on parametric and non parametric estimation of the distributions generated by the Marshall-Olkin copula. This copula comes from the Marshall-Olkin bivariate exponential distribution used in reliability analysis. We generalize this model by the copula and different marginal distributions to construct several bivariate survival functions. The cumulative distribution functions are not absolutely continuous and they unknown parameters are often not be obtained in explicit form. In order to estimate the parameters we propose an easy procedure based on the moments. This method consist in two steps: in the first step we estimate only the parameters of marginal distributions and in the second step we estimate only the copula parameter. This procedure can be used to estimate the parameters of complex survival functions in which it is difficult to find an explicit expression of the mixed moments. Moreover it is preferred to the maximum likelihood one for its simplex mathematic form; in particular for distributions whose maximum likelihood parameters estimators can not be obtained in explicit form.

  15. Issues concerning Landowner Management Plan Adoption Decisions: A Recursive Bivariate Probit Approach

    Directory of Open Access Journals (Sweden)

    Omkar Joshi

    2015-01-01

    Full Text Available Despite the likely benefits of having a written forest management plan, a small number of landowners in the United States have the one. A recursive bivariate probit model was used to identify the possible relationship between landowners’ decision to obtain a management plan and their interest in future timber harvesting. Our study results based on recursive bivariate model suggest that landowners having larger land ownerships, longer forest ownership tenure, and higher education were more likely to have a forest management plan and future timber harvesting interest. While the landowners having interest for wildlife management were also interested to have a written management plan, they did not prefer to harvest in future. Study results indicate that written management plan means more than a timber harvesting strategy to landowners in general. Many elderly landowners with a low level of income and less formal education and those having small or medium sized tracts of forestland are less likely to own a written management plan. Therefore, this group requires special attention in various government sponsored forest management related extension activities. Future research on understanding landowner perception behind written management plan is recommended.

  16. Exploiting Bivariate Dependencies to Speedup Structure Learning in Bayesian Optimization Algorithm

    Institute of Scientific and Technical Information of China (English)

    Amin Nikanjam; Adel Rahmani

    2012-01-01

    Bayesian optimization algorithm (BOA) is one of the successful and widely used estimation of distribution algorithms (EDAs) which have been employed to solve different optimization problems.In EDAs,a model is learned from the selected population that encodes interactions among problem variables.New individuals are generated by sampling the model and incorporated into the population.Different probabilistic models have been used in EDAs to learn interactions.Bayesian network (BN) is a well-known graphical model which is used in BOA.Learning a proper model in EDAs and particularly in BOA is distinguished as a computationally expensive task.Different methods have been proposed in the literature to improve the complexity of model building in EDAs.This paper employs bivariate dependencies to learn accurate BNs in BOA efficiently.The proposed approach extracts the bivariate dependencies using an appropriate pairwise interaction-detection metric.Due to the static structure of the underlying problems,these dependencies are used in each generation of BOA to learn an accurate network.By using this approach,the computational cost of model building is reduced dramatically.Various optimization problems are selected to be solved by the algorithm.The experimental results show that the proposed approach successfully finds the optimum in problems with different types of interactions efficiently.Significant speedups are observed in the model building procedure as well.

  17. Reconciliation of size-density bivariate distributions over a separating node

    Institute of Scientific and Technical Information of China (English)

    Bidarahalli Venkoba Rao; Vivek Ganvir; Sirigeri Jois Gopalakrishna

    2008-01-01

    Data reconciliation considers the restoration of mass balance among the noise prone measured data by way of component adjustments for the various particle size or particle density classes or assays over the separating node. In this paper, the method of Lagrange multipliers has been extended to balance bivariate feed and product size-density distributions of coal particles split from a settling column. The settling suspension in the column was split into two product fractions at 40% height from the bottom after a minute settling of homogenized suspension at start. Reconciliation of data assists to estimate solid flow split of particles to the settled stream as well as helps to calculate the profiles of partition curves of the marginal particle size or particle density distributions. In general, Lagrange multiplier method with uniform weighting of its components may not guarantee a smooth partition surface and thus the reconciled data needs further refinement to establish the nature of the surface. In order to overcome this difficulty, a simple alternative method of reconciling bivariate size-density data using partition surface concept is explored in this paper.

  18. Testing for central symmetry

    NARCIS (Netherlands)

    Einmahl, John; Gan, Zhuojiong

    2016-01-01

    Omnibus tests for central symmetry of a bivariate probability distribution are proposed. The test statistics compare empirical measures of opposite regions. Under rather weak conditions, we establish the asymptotic distribution of the test statistics under the null hypothesis; it follows that they a

  19. On the Bivariate Nakagami-Lognormal Distribution and Its Correlation Properties

    Directory of Open Access Journals (Sweden)

    Juan Reig

    2014-01-01

    Full Text Available The bivariate Nakagami-lognormal distribution used to model the composite fast fading and shadowing has been examined exhaustively. In particular, we have derived the joint probability density function, the cross-moments, and the correlation coefficient in power terms. Also, two procedures to generate two correlated Nakagami-lognormal random variables are described. These procedures can be used to evaluate the robustness of the sample correlation coefficient distribution in both macro- and microdiversity scenarios. It is shown that the bias and the standard deviation of this sample correlation coefficient are substantially high for large shadowing standard deviations found in wireless communication measurements, even if the number of observations is considerable.

  20. Bayesian bivariate generalized Lindley model for survival data with a cure fraction.

    Science.gov (United States)

    Martinez, Edson Z; Achcar, Jorge A

    2014-11-01

    The cure fraction models have been widely used to analyze survival data in which a proportion of the individuals is not susceptible to the event of interest. In this article, we introduce a bivariate model for survival data with a cure fraction based on the three-parameter generalized Lindley distribution. The joint distribution of the survival times is obtained by using copula functions. We consider three types of copula function models, the Farlie-Gumbel-Morgenstern (FGM), Clayton and Gumbel-Barnett copulas. The model is implemented under a Bayesian framework, where the parameter estimation is based on Markov Chain Monte Carlo (MCMC) techniques. To illustrate the utility of the model, we consider an application to a real data set related to an invasive cervical cancer study.

  1. A Bivariate Chebyshev Spectral Collocation Quasilinearization Method for Nonlinear Evolution Parabolic Equations

    Directory of Open Access Journals (Sweden)

    S. S. Motsa

    2014-01-01

    Full Text Available This paper presents a new method for solving higher order nonlinear evolution partial differential equations (NPDEs. The method combines quasilinearisation, the Chebyshev spectral collocation method, and bivariate Lagrange interpolation. In this paper, we use the method to solve several nonlinear evolution equations, such as the modified KdV-Burgers equation, highly nonlinear modified KdV equation, Fisher's equation, Burgers-Fisher equation, Burgers-Huxley equation, and the Fitzhugh-Nagumo equation. The results are compared with known exact analytical solutions from literature to confirm accuracy, convergence, and effectiveness of the method. There is congruence between the numerical results and the exact solutions to a high order of accuracy. Tables were generated to present the order of accuracy of the method; convergence graphs to verify convergence of the method and error graphs are presented to show the excellent agreement between the results from this study and the known results from literature.

  2. Noise Removal From Microarray Images Using Maximum a Posteriori Based Bivariate Estimator

    Directory of Open Access Journals (Sweden)

    A.Sharmila Agnal

    2013-01-01

    Full Text Available Microarray Image contains information about thousands of genes in an organism and these images are affected by several types of noises. They affect the circular edges of spots and thus degrade the image quality. Hence noise removal is the first step of cDNA microarray image analysis for obtaining gene expression level and identifying the infected cells. The Dual Tree Complex Wavelet Transform (DT-CWT is preferred for denoising microarray images due to its properties like improved directional selectivity and near shift-invariance. In this paper, bivariate estimators namely Linear Minimum Mean Squared Error (LMMSE and Maximum A Posteriori (MAP derived by applying DT-CWT are used for denoising microarray images. Experimental results show that MAP based denoising method outperforms existing denoising techniques for microarray images.

  3. A New Method of Constructing Bivariate Vector Valued Rational Interpolation Function

    Institute of Scientific and Technical Information of China (English)

    Lin ZHENGI; Gong Qin ZHU

    2011-01-01

    At present,the methods of constructing vector valued rational interpolation function in rectangular mesh are mainly presented by means of the branched continued fractions.In order to get vector valued rational interpolation function with lower degree and better approximation effect,the paper divides rectangular mesh into pieces by choosing nonnegative integer parameters d1(0≤di ≤ m) and d2 (0≤d2 ≤n),builds bivariate polynomial vector interpolation for each piece,then combines with them properly.As compared with previous methods,the new method given by this paper is easy to compute and the degree for the interpolants is lower.

  4. A bivariate Chebyshev spectral collocation quasilinearization method for nonlinear evolution parabolic equations.

    Science.gov (United States)

    Motsa, S S; Magagula, V M; Sibanda, P

    2014-01-01

    This paper presents a new method for solving higher order nonlinear evolution partial differential equations (NPDEs). The method combines quasilinearisation, the Chebyshev spectral collocation method, and bivariate Lagrange interpolation. In this paper, we use the method to solve several nonlinear evolution equations, such as the modified KdV-Burgers equation, highly nonlinear modified KdV equation, Fisher's equation, Burgers-Fisher equation, Burgers-Huxley equation, and the Fitzhugh-Nagumo equation. The results are compared with known exact analytical solutions from literature to confirm accuracy, convergence, and effectiveness of the method. There is congruence between the numerical results and the exact solutions to a high order of accuracy. Tables were generated to present the order of accuracy of the method; convergence graphs to verify convergence of the method and error graphs are presented to show the excellent agreement between the results from this study and the known results from literature.

  5. Utility of testing for apraxia and associated features in dementia

    Science.gov (United States)

    Ahmed, Samrah; Baker, Ian; Thompson, Sian; Husain, Masud; Butler, Christopher R

    2016-01-01

    Introduction Existing literature suggests that the presence or absence of apraxia and associated parietal deficits may be clinically relevant in differential diagnosis of dementia syndromes. Aim This study investigated the profile of these features in Alzheimer's disease (AD) and frontotemporal dementia (FTD) spectrum disorders, at first presentation. Methods Retrospective case note analysis was undertaken in 111 patients who presented to the Oxford Cognitive Disorders Clinic, Oxford, UK, including 29 amnestic AD, 12 posterior cortical atrophy (PCA), 12 logopenic primary progressive aphasia (lvPPA), 20 behavioural variant FTD (bvFTD), 7 non-fluent variant PPA (nfvPPA), 6 semantic variant PPA (svPPA) and 25 patients with subjective cognitive impairment (SCI). The clinical features of interest were: limb apraxia, apraxia of speech (AOS), and left parietal symptoms of dyslexia, dysgraphia, and dyscalculia. Results The prevalence of limb apraxia was highest in PCA, amnestic AD, lvPPA and nfvPPA. AOS was only observed in nfvPPA. Associated parietal features were more prevalent in AD spectrum than FTD spectrum disorders. Group comparisons between key differential diagnostic challenges showed that lvPPA and nfvPPA could be significantly differentiated on the presence of left parietal features and AOS, and amnestic AD could be differentiated from bvFTD, svPPA and SCI by limb apraxia. Regression analysis showed that limb apraxia could successfully differentiate between AD and FTLD spectrum disorders with 83% accuracy. Discussion Disease-specific profiles of limb apraxia and associated deficits can be observed. FTD and AD spectrum disorders can be difficult to differentiate due to overlapping cognitive symptoms, and measures of apraxia, in particular, appear to be a promising discriminator. PMID:27251676

  6. A Biochar Classification System and Associated Test Methods

    Energy Technology Data Exchange (ETDEWEB)

    Camps-Arbestain, Marta; Amonette, James E.; Singh, Balwant; Wang, Tao; Schmidt, Hans-Peter

    2015-02-18

    In this chapter, a biochar classification system related to its use as soil amendment is proposed. This document builds upon previous work and constrains its scope to materials with properties that satisfy the criteria for biochar as defined by either the International Biochar Initiative (IBI) Biochar Standards or the European Biochar Community (EBC) Standards, and it is intended to minimise the need for testing in addition to those required according to the above-mentioned standards. The classification system envisions enabling stakeholders and commercial entities to (i) identify the most suitable biochar to fulfil the requirements for a particular soil and/or land-use, and (ii) distinguish the application of biochar for specific niches (e.g., soilless agriculture). It is based on the best current knowledge and the intention is to periodically review and update the document based on new data and knowledge that become available in the scientific literature. The main thrust of this classification system is based on the direct or indirect beneficial effects that biochar provides from its application to soil. We have classified the potential beneficial effects of biochar application to soils into five categories with their corresponding classes, where applicable: (i) carbon (C) storage value, (ii) fertiliser value, (iii) liming value, (iv) particle-size, and (v) use in soil-less agriculture. A summary of recommended test methods is provided at the end of the chapter.

  7. Rare variant testing across methods and thresholds using the multi-kernel sequence kernel association test (MK-SKAT).

    Science.gov (United States)

    Urrutia, Eugene; Lee, Seunggeun; Maity, Arnab; Zhao, Ni; Shen, Judong; Li, Yun; Wu, Michael C

    Analysis of rare genetic variants has focused on region-based analysis wherein a subset of the variants within a genomic region is tested for association with a complex trait. Two important practical challenges have emerged. First, it is difficult to choose which test to use. Second, it is unclear which group of variants within a region should be tested. Both depend on the unknown true state of nature. Therefore, we develop the Multi-Kernel SKAT (MK-SKAT) which tests across a range of rare variant tests and groupings. Specifically, we demonstrate that several popular rare variant tests are special cases of the sequence kernel association test which compares pair-wise similarity in trait value to similarity in the rare variant genotypes between subjects as measured through a kernel function. Choosing a particular test is equivalent to choosing a kernel. Similarly, choosing which group of variants to test also reduces to choosing a kernel. Thus, MK-SKAT uses perturbation to test across a range of kernels. Simulations and real data analyses show that our framework controls type I error while maintaining high power across settings: MK-SKAT loses power when compared to the kernel for a particular scenario but has much greater power than poor choices.

  8. Evaluation of PCR on bronchoalveolar lavage fluid for diagnosis of invasive aspergillosis: a bivariate metaanalysis and systematic review.

    Directory of Open Access Journals (Sweden)

    Wenkui Sun

    Full Text Available BACKGROUND: Nucleic acid detection by polymerase chain reaction (PCR is emerging as a sensitive and rapid diagnostic tool. PCR assays on serum have the potential to be a practical diagnostic tool. However, PCR on bronchoalveolar lavage fluid (BALF has not been well established. We performed a systematic review of published studies to evaluate the diagnostic accuracy of PCR assays on BALF for invasive aspergillosis (IA. METHODS: Relevant published studies were shortlisted to evaluate the quality of their methodologies. A bivariate regression approach was used to calculate pooled values of the method sensitivity, specificity, and positive and negative likelihood ratios. Hierarchical summary receiver operating characteristic curves were used to summarize overall performance. We calculated the post-test probability to evaluate clinical usefulness. Potential heterogeneity among studies was explored by subgroup analyses. RESULTS: Seventeen studies comprising 1191 at-risk patients were selected. The summary estimates of the BALF-PCR assay for proven and probable IA were as follows: sensitivity, 0.91 (95% confidence interval (CI, 0.79-0.96; specificity, 0.92 (95% CI, 0.87-0.96; positive likelihood ratio, 11.90 (95% CI, 6.80-20.80; and negative likelihood ratio, 0.10 (95% CI, 0.04-0.24. Subgroup analyses showed that the performance of the PCR assay was influenced by PCR assay methodology, primer design and the methods of cell wall disruption and DNA extraction. CONCLUSIONS: PCR assay on BALF is highly accurate for diagnosing IA in immunocompromised patients and is likely to be a useful diagnostic tool. However, further efforts towards devising a standard protocol are needed to enable formal validation of BALF-PCR.

  9. On the Relationship between Pearson Correlation Coefficient and Kendall’s Tau under Bivariate Homogeneous Shock Model

    OpenAIRE

    Jiantian Wang

    2012-01-01

    This paper studies the relationship between Kendall's tau and Pearson correlation coefficient under the so-called bivariate homogeneous shock (BHS) model. We find Capéraà-Genest-type inequality may not hold for general BHS model. Computational simulations suggest that the Denials' inequality is likely to be true.

  10. Application of bivariate mapping for hydrological classification and analysis of temporal change and scale effects in Switzerland

    NARCIS (Netherlands)

    Speich, Matthias J.R.; Bernhard, Luzi; Teuling, Ryan; Zappa, Massimiliano

    2015-01-01

    Hydrological classification schemes are important tools for assessing the impacts of a changing climate on the hydrology of a region. In this paper, we present bivariate mapping as a simple means of classifying hydrological data for a quantitative and qualitative assessment of temporal change. Bi

  11. Testing hypotheses associated with bird responses to wildfire.

    Science.gov (United States)

    Lindenmayer, David B; Wood, Jeff T; Cunningham, Ross B; MacGregor, Christopher; Crane, Mason; Michael, Damian; Montague-Drake, Rebecca; Brown, Darren; Muntz, Rachel; Gill, A Malcolm

    2008-12-01

    Disturbance is a key ecological process influencing the distribution and abundance of many elements of the earth's biota. Predicting the response of biota to disturbance is therefore important, but it nevertheless remains difficult to make accurate forecasts of response. We tested predictions from disturbance-related theories and concepts in 10 vegetation types at Booderee National Park (southeastern Australia) using a retrospective study of bird responses to fire history (over 35 years) on 110 sites and a prospective study following a single wildfire event in 2003 at 59 of these sites. Our data did not support predictions from the intermediate-disturbance hypothesis; observed bird species richness at a site was significantly (F(1,99) = 6.30, P = 0.014) negatively related to the number of fires since 1972 and was 8.7% lower (95% CI, 1.8-15.1%) for each additional fire. In contrast to fire history effects, we found that after the 2003 fire, the vast majority of individual species and the bird assemblage per se in most vegetation types recovered within two years. Thus, recovery after a single fire did not reflect long-term effects of multiple fires on overall bird species richness at a site. We postulated that the recovery of bird species richness and bird assemblage composition after the 2003 fire would be fastest in structurally simple vegetation types and slowest in structurally complex vegetation, but observed the opposite. Although observed bird species richness in vertically heterogeneous forest and woodland had returned to prefire levels by 2006, bird species richness in structurally simple vegetation types (e.g., sedgeland) had not. Postfire vegetation regeneration, together with a paucity of early-successional specialists, would explain the speed of recovery of the bird assemblage and why it changed relatively little during our investigation.

  12. Error Estimates of Fitting for Bivariate Fractal Interpolation%二元分形插值的拟合误差估计

    Institute of Scientific and Technical Information of China (English)

    王宏勇

    2009-01-01

    A given bivariate continuous function is fitted by using a bivariate fractal interpolation function, and the error of fitting is studied in this paper. The results of error estimates are obtained in two metric cases. This provides a theoretical basis for the algorithms of fractal surface reconstruction.

  13. Synthetic control charts with two-stage sampling for monitoring bivariate processes

    Directory of Open Access Journals (Sweden)

    Antonio F. B. Costa

    2007-04-01

    Full Text Available In this article, we consider the synthetic control chart with two-stage sampling (SyTS chart to control bivariate processes. During the first stage, one item of the sample is inspected and two correlated quality characteristics (x;y are measured. If the Hotelling statistic T1² for these individual observations of (x;y is lower than a specified value UCL1 the sampling is interrupted. Otherwise, the sampling goes on to the second stage, where the remaining items are inspected and the Hotelling statistic T2² for the sample means of (x;y is computed. When the statistic T2² is larger than a specified value UCL2, the sample is classified as nonconforming. According to the synthetic control chart procedure, the signal is based on the number of conforming samples between two neighbor nonconforming samples. The proposed chart detects process disturbances faster than the bivariate charts with variable sample size and it is from the practical viewpoint more convenient to administer.Este artigo apresenta um gráfico de controle com regra especial de decisão e amostragens em dois estágios para o monitoramento de processos bivariados. No primeiro estágio, um item da amostra é inspecionado e duas características de qualidade correlacionadas (x;y são medidas. Se a estatística de Hotelling T1² para as observações individuais de (x;y for menor que um valor especificado UCL1 a amostragem é interrompida. Caso contrário, a amostragem segue para o segundo estágio, onde os demais itens da amostra são inspecionados e a estatística de Hotelling T2² para as médias de (x;y é calculada. Quando a estatística T2² é maior que um valor especificado UCL2, a amostra é classificada como não conforme. De acordo com a regra especial de decisão, o alarme é baseado no número de amostras entre duas não conformes. O gráfico proposto é mais ágil e mais simples do ponto de vista operacional que o gráfico de controle bivariado com tamanho de amostras variável.

  14. [Bivariate statistical model for calculating phosphorus input loads to the river from point and nonpoint sources].

    Science.gov (United States)

    Chen, Ding-Jiang; Sun, Si-Yang; Jia, Ying-Na; Chen, Jia-Bo; Lü, Jun

    2013-01-01

    Based on the hydrological difference between the point source (PS) and nonpoint source (NPS) pollution processes and the major influencing mechanism of in-stream retention processes, a bivariate statistical model was developed for relating river phosphorus load to river water flow rate and temperature. Using the calibrated and validated four model coefficients from in-stream monitoring data, monthly phosphorus input loads to the river from PS and NPS can be easily determined by the model. Compared to current hydrologica methods, this model takes the in-stream retention process and the upstream inflow term into consideration; thus it improves the knowledge on phosphorus pollution processes and can meet the requirements of both the district-based and watershed-based wate quality management patterns. Using this model, total phosphorus (TP) input load to the Changle River in Zhejiang Province was calculated. Results indicated that annual total TP input load was (54.6 +/- 11.9) t x a(-1) in 2004-2009, with upstream water inflow, PS and NPS contributing to 5% +/- 1%, 12% +/- 3% and 83% +/- 3%, respectively. The cumulative NPS TP input load during the high flow periods (i. e. , June, July, August and September) in summer accounted for 50% +/- 9% of the annual amount, increasing the alga blooming risk in downstream water bodies. Annual in-stream TP retention load was (4.5 +/- 0.1) t x a(-1) and occupied 9% +/- 2% of the total input load. The cumulative in-stream TP retention load during the summer periods (i. e. , June-September) accounted for 55% +/- 2% of the annual amount, indicating that in-stream retention function plays an important role in seasonal TP transport and transformation processes. This bivariate statistical model only requires commonly available in-stream monitoring data (i. e. , river phosphorus load, water flow rate and temperature) with no requirement of special software knowledge; thus it offers researchers an managers with a cost-effective tool for

  15. 12 CFR 563e.25 - Community development test for wholesale or limited purpose savings associations.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Community development test for wholesale or... SUPERVISION, DEPARTMENT OF THE TREASURY COMMUNITY REINVESTMENT Standards for Assessing Performance § 563e.25 Community development test for wholesale or limited purpose savings associations. (a) Scope of test. The...

  16. Computerized Testing of Level III Associate Degree Nursing Students versus Paper and Pencil Testing Methods

    Science.gov (United States)

    Gullo, Shirna R.

    2014-01-01

    Computerized testing may be one solution to enhance performance on the curricular Health Education Systems Inc. (HESI) exam and the National Council Licensure Exam for Registered Nurses (NCLEX-RN). Due to the integration of improved technological processes and procedures in healthcare for computerized documentation and electronicmedical records,…

  17. A bivariate binormal ROC methodology for comparing new methods to an existing standard for screening applications

    Science.gov (United States)

    Abbey, Craig K.; Insana, Michael F.; Eckstein, Miguel P.; Boone, John M.

    2007-03-01

    Validating the use of new imaging technologies for screening large patient populations is an important and very challenging area of diagnostic imaging research. A particular concern in ROC studies evaluating screening technologies is the problem of verification bias, in which an independent verification of disease status is only available for a subpopulation of patients, typically those with positive results by a current screening standard. For example, in screening mammography, a study might evaluate a new approach using a sample of patients that have undergone needle biopsy following a standard mammogram and subsequent work-up. This case sampling approach provides accurate independent verification of ground truth and increases the prevalence of disease cases. However, the selection criteria will likely bias results of the study. In this work we present an initial exploration of an approach to correcting this bias within the parametric framework of binormal assumptions. We posit conditionally bivariate normal distributions on the latent decision variable for both the new methodology as well as the screening standard. In this case, verification bias can be seen as the effect of missing data from an operating point in the screening standard. We examine the magnitude of this bias in the setting of breast cancer screening with mammography, and we derive a maximum likelihood approach to estimating bias corrected ROC curves in this model.

  18. A bivariate quantitative genetic model for a linear Gaussian trait and a survival trait

    Directory of Open Access Journals (Sweden)

    Damgaard Lars

    2005-12-01

    Full Text Available Abstract With the increasing use of survival models in animal breeding to address the genetic aspects of mainly longevity of livestock but also disease traits, the need for methods to infer genetic correlations and to do multivariate evaluations of survival traits and other types of traits has become increasingly important. In this study we derived and implemented a bivariate quantitative genetic model for a linear Gaussian and a survival trait that are genetically and environmentally correlated. For the survival trait, we considered the Weibull log-normal animal frailty model. A Bayesian approach using Gibbs sampling was adopted. Model parameters were inferred from their marginal posterior distributions. The required fully conditional posterior distributions were derived and issues on implementation are discussed. The twoWeibull baseline parameters were updated jointly using a Metropolis-Hastingstep. The remaining model parameters with non-normalized fully conditional distributions were updated univariately using adaptive rejection sampling. Simulation results showed that the estimated marginal posterior distributions covered well and placed high density to the true parameter values used in the simulation of data. In conclusion, the proposed method allows inferring additive genetic and environmental correlations, and doing multivariate genetic evaluation of a linear Gaussian trait and a survival trait.

  19. A bivariate quantitative genetic model for a linear Gaussian trait and a survival trait.

    Science.gov (United States)

    Damgaard, Lars Holm; Korsgaard, Inge Riis

    2006-01-01

    With the increasing use of survival models in animal breeding to address the genetic aspects of mainly longevity of livestock but also disease traits, the need for methods to infer genetic correlations and to do multivariate evaluations of survival traits and other types of traits has become increasingly important. In this study we derived and implemented a bivariate quantitative genetic model for a linear Gaussian and a survival trait that are genetically and environmentally correlated. For the survival trait, we considered the Weibull log-normal animal frailty model. A Bayesian approach using Gibbs sampling was adopted. Model parameters were inferred from their marginal posterior distributions. The required fully conditional posterior distributions were derived and issues on implementation are discussed. The two Weibull baseline parameters were updated jointly using a Metropolis-Hasting step. The remaining model parameters with non-normalized fully conditional distributions were updated univariately using adaptive rejection sampling. Simulation results showed that the estimated marginal posterior distributions covered well and placed high density to the true parameter values used in the simulation of data. In conclusion, the proposed method allows inferring additive genetic and environmental correlations, and doing multivariate genetic evaluation of a linear Gaussian trait and a survival trait.

  20. Effects of three heavy metals on the bacteria growth kinetics. A bivariate model for toxicological assessment

    Energy Technology Data Exchange (ETDEWEB)

    Rial, Diego; Vazquez, Jose Antonio; Murado, Miguel Anxo [Instituto de Investigacions Marinas (CSIC), Vigo (ES). Grupo de Reciclado y Valorizacion de Materiales Residuales (REVAL)

    2011-05-15

    The effects of three heavy metals (Co, Ni and Cd) on the growth kinetics of five bacterial strains with different characteristics (Pseudomonas sp., Phaeobacter sp. strain 27-4, Listonella anguillarum, Carnobacterium piscicola and Leuconostoc mesenteroides subsp. lysis) were studied in a batch system. A bivariate model, function of time and dose, is proposed to describe simultaneously all the kinetic profiles obtained by incubating a microorganism at increasing concentrations of individual metals. This model combines the logistic equation for describing growth, with a modification of the cumulative Weibull's function for describing the dose-dependent variations of growth parameters. The comprehensive model thus obtained - which minimizes the effects of the experimental error - was statistically significant in all the studied cases, and it raises doubts about toxicological evaluations that are based on a single growth parameter, especially if it is not obtained from a kinetic equation. In lactic acid bacteria cultures (C. piscicola and L. mesenteroides), Cd induced remarkable differences in yield and time course of characteristic metabolites. A global parameter is defined (ED{sub 50,{tau}}: dose of toxic chemical that reduces the biomass of a culture by 50% compared to that produced by the control at the time corresponding to its semi maximum biomass) that allows comparing toxic effects on growth kinetics using a single value. (orig.)

  1. Bayesian Data Analysis with the Bivariate Hierarchical Ornstein-Uhlenbeck Process Model.

    Science.gov (United States)

    Oravecz, Zita; Tuerlinckx, Francis; Vandekerckhove, Joachim

    2016-01-01

    In this paper, we propose a multilevel process modeling approach to describing individual differences in within-person changes over time. To characterize changes within an individual, repeated measures over time are modeled in terms of three person-specific parameters: a baseline level, intraindividual variation around the baseline, and regulatory mechanisms adjusting toward baseline. Variation due to measurement error is separated from meaningful intraindividual variation. The proposed model allows for the simultaneous analysis of longitudinal measurements of two linked variables (bivariate longitudinal modeling) and captures their relationship via two person-specific parameters. Relationships between explanatory variables and model parameters can be studied in a one-stage analysis, meaning that model parameters and regression coefficients are estimated simultaneously. Mathematical details of the approach, including a description of the core process model-the Ornstein-Uhlenbeck model-are provided. We also describe a user friendly, freely accessible software program that provides a straightforward graphical interface to carry out parameter estimation and inference. The proposed approach is illustrated by analyzing data collected via self-reports on affective states.

  2. Improved deadzone modeling for bivariate wavelet shrinkage-based image denoising

    Science.gov (United States)

    DelMarco, Stephen

    2016-05-01

    Modern image processing performed on-board low Size, Weight, and Power (SWaP) platforms, must provide high- performance while simultaneously reducing memory footprint, power consumption, and computational complexity. Image preprocessing, along with downstream image exploitation algorithms such as object detection and recognition, and georegistration, place a heavy burden on power and processing resources. Image preprocessing often includes image denoising to improve data quality for downstream exploitation algorithms. High-performance image denoising is typically performed in the wavelet domain, where noise generally spreads and the wavelet transform compactly captures high information-bearing image characteristics. In this paper, we improve modeling fidelity of a previously-developed, computationally-efficient wavelet-based denoising algorithm. The modeling improvements enhance denoising performance without significantly increasing computational cost, thus making the approach suitable for low-SWAP platforms. Specifically, this paper presents modeling improvements to the Sendur-Selesnick model (SSM) which implements a bivariate wavelet shrinkage denoising algorithm that exploits interscale dependency between wavelet coefficients. We formulate optimization problems for parameters controlling deadzone size which leads to improved denoising performance. Two formulations are provided; one with a simple, closed form solution which we use for numerical result generation, and the second as an integral equation formulation involving elliptic integrals. We generate image denoising performance results over different image sets drawn from public domain imagery, and investigate the effect of wavelet filter tap length on denoising performance. We demonstrate denoising performance improvement when using the enhanced modeling over performance obtained with the baseline SSM model.

  3. Bivariate spatial analysis of temperature and precipitation from general circulation models and observation proxies

    KAUST Repository

    Philbin, R.

    2015-05-22

    This study validates the near-surface temperature and precipitation output from decadal runs of eight atmospheric ocean general circulation models (AOGCMs) against observational proxy data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis temperatures and Global Precipitation Climatology Project (GPCP) precipitation data. We model the joint distribution of these two fields with a parsimonious bivariate Matérn spatial covariance model, accounting for the two fields\\' spatial cross-correlation as well as their own smoothnesses. We fit output from each AOGCM (30-year seasonal averages from 1981 to 2010) to a statistical model on each of 21 land regions. Both variance and smoothness values agree for both fields over all latitude bands except southern mid-latitudes. Our results imply that temperature fields have smaller smoothness coefficients than precipitation fields, while both have decreasing smoothness coefficients with increasing latitude. Models predict fields with smaller smoothness coefficients than observational proxy data for the tropics. The estimated spatial cross-correlations of these two fields, however, are quite different for most GCMs in mid-latitudes. Model correlation estimates agree well with those for observational proxy data for Australia, at high northern latitudes across North America, Europe and Asia, as well as across the Sahara, India, and Southeast Asia, but elsewhere, little consistent agreement exists.

  4. Estimation of flood design hydrographs using bivariate analysis (copula and distributed hydrological modelling

    Directory of Open Access Journals (Sweden)

    A. Candela

    2014-01-01

    Full Text Available In this paper a procedure to derive Flood Design Hydrographs (FDH using a bivariate representation of rainfall forcing (rainfall duration and intensity using copulas, which describe and model the correlation between these two variables independently of the marginal laws involved, coupled with a distributed rainfall-runoff model is presented. Rainfall-runoff modelling for estimating the hydrological response at the outlet of a watershed used a conceptual fully distributed procedure based on the soil conservation service – curve number method as excess rainfall model and a distributed unit hydrograph with climatic dependencies for the flow routing. Travel time computation, based on the definition of a distributed unit hydrograph, has been performed, implementing a procedure using flow paths determined from a digital elevation model (DEM and roughness parameters obtained from distributed geographical information. In order to estimate the return period of the FDH which give the probability of occurrence of a hydrograph flood peaks and flow volumes obtained through R-R modeling has been statistically treated via copulas. The shape of hydrograph has been generated on the basis of a modeled flood events, via cluster analysis. The procedure described above was applied to a case study of Imera catchment in Sicily, Italy. The methodology allows a reliable and estimation of the Design Flood Hydrograph and can be used for all the flood risk applications, i.e. evaluation, management, mitigation, etc.

  5. Modeling both of the number of pausibacillary and multibacillary leprosy patients by using bivariate poisson regression

    Science.gov (United States)

    Winahju, W. S.; Mukarromah, A.; Putri, S.

    2015-03-01

    Leprosy is a chronic infectious disease caused by bacteria of leprosy (Mycobacterium leprae). Leprosy has become an important thing in Indonesia because its morbidity is quite high. Based on WHO data in 2014, in 2012 Indonesia has the highest number of new leprosy patients after India and Brazil with a contribution of 18.994 people (8.7% of the world). This number makes Indonesia automatically placed as the country with the highest number of leprosy morbidity of ASEAN countries. The province that most contributes to the number of leprosy patients in Indonesia is East Java. There are two kind of leprosy. They consist of pausibacillary and multibacillary. The morbidity of multibacillary leprosy is higher than pausibacillary leprosy. This paper will discuss modeling both of the number of multibacillary and pausibacillary leprosy patients as responses variables. These responses are count variables, so modeling will be conducted by using bivariate poisson regression method. Unit experiment used is in East Java, and predictors involved are: environment, demography, and poverty. The model uses data in 2012, and the result indicates that all predictors influence significantly.

  6. The Bivariate Size-luminosity Relations for Lyman Break Galaxies at z ~ 4 - 5

    CERN Document Server

    Huang, Kuang-Han; Ravindranath, Swara; Su, Jian

    2013-01-01

    We study the bivariate size-luminosity distribution of Lyman Break Galaxies (LBGs) selected at redshifts around 4 and 5 in GOODS and the HUDF fields. We model the size-luminosity distribution as a combination of log-normal distribution (in size) and Schechter function (in luminosity), therefore it enables a more detailed study of the selection effects. We perform extensive simulations to quantify the dropout-selection completenesses and measurement biases and uncertainties in two-dimensional size and magnitude bins, and transform the theoretical size-luminosity distribution to the expected distribution for the observed data. Using maximum-likelihood estimator (MLE), we find that the Schechter function parameters for B-dropouts are \\alpha=-1.68^{+0.068}_{-0.095}, M*=-20.60^{+0.13}_{-0.17}, and \\phi*=1.79^{+0.32}_{-0.52} x 10^{-3} Mpc^{-3}. The log-normal size distribution is characterized by the peak R_0=1.34^{+0.099}_{-0.108} kpc at M_{1500}=-21 mag, width \\sigma_{\\lnR}=0.83^{+0.046}_{-0.044}, and the slope o...

  7. A small-sample multivariate kernel machine test for microbiome association studies.

    Science.gov (United States)

    Zhan, Xiang; Tong, Xingwei; Zhao, Ni; Maity, Arnab; Wu, Michael C; Chen, Jun

    2017-04-01

    High-throughput sequencing technologies have enabled large-scale studies of the role of the human microbiome in health conditions and diseases. Microbial community level association test, as a critical step to establish the connection between overall microbiome composition and an outcome of interest, has now been routinely performed in many studies. However, current microbiome association tests all focus on a single outcome. It has become increasingly common for a microbiome study to collect multiple, possibly related, outcomes to maximize the power of discovery. As these outcomes may share common mechanisms, jointly analyzing these outcomes can amplify the association signal and improve statistical power to detect potential associations. We propose the multivariate microbiome regression-based kernel association test (MMiRKAT) for testing association between multiple continuous outcomes and overall microbiome composition, where the kernel used in MMiRKAT is based on Bray-Curtis or UniFrac distance. MMiRKAT directly regresses all outcomes on the microbiome profiles via a semiparametric kernel machine regression framework, which allows for covariate adjustment and evaluates the association via a variance-component score test. Because most of the current microbiome studies have small sample sizes, a novel small-sample correction procedure is implemented in MMiRKAT to correct for the conservativeness of the association test when the sample size is small or moderate. The proposed method is assessed via simulation studies and an application to a real data set examining the association between host gene expression and mucosal microbiome composition. We demonstrate that MMiRKAT is more powerful than large sample based multivariate kernel association test, while controlling the type I error. A free implementation of MMiRKAT in R language is available at http://research.fhcrc.org/wu/en.html.

  8. "Passageless" administration of the Nelson-Denny Reading Comprehension Test: associations with IQ and reading skills.

    Science.gov (United States)

    Ready, Rebecca E; Chaudhry, Maheen F; Schatz, Kelly C; Strazzullo, Sarah

    2013-01-01

    There are few tests that assess reading comprehension in adults, but these tests are needed for a comprehensive assessment of reading disorders (RD). The Nelson-Denny Reading Test (NDRT) has a long-passage reading comprehension component that can be used with adolescents and adults. A problem with the NDRT is that reading comprehension test items can be answered correctly without reading the associated passage. The current study determined how IQ, verbal comprehension, and reading skills were associated with scores on a passageless administration of the NDRT. Results indicated that IQ, verbal comprehension, and broad reading skills were significantly associated with greater NDRT passageless scores. Results raise questions about the validity of the reading comprehension component of the NDRT and suggest that the test may have differential validity based on individual differences in vocabulary, general fund of knowledge, and broad reading skills.

  9. On the level of skill in predicting maximum sunspot number - A comparative study of single variate and bivariate precursor techniques

    Science.gov (United States)

    Wilson, Robert M.

    1990-01-01

    The level of skill in predicting the size of the sunspot cycle is investigated for the two types of precursor techniques, single variate and bivariate fits, both applied to cycle 22. The present level of growth in solar activity is compared to the mean level of growth (cycles 10-21) and to the predictions based on the precursor techniques. It is shown that, for cycle 22, both single variate methods (based on geomagnetic data) and bivariate methods suggest a maximum amplitude smaller than that observed for cycle 19, and possibly for cycle 21. Compared to the mean cycle, cycle 22 is presently behaving as if it were a +2.6 sigma cycle (maximum amplitude of about 225), which means that either it will be the first cycle not to be reliably predicted by the combined precursor techniques or its deviation relative to the mean cycle will substantially decrease over the next 18 months.

  10. Testing in Microbiome-Profiling Studies with MiRKAT, the Microbiome Regression-Based Kernel Association Test.

    Science.gov (United States)

    Zhao, Ni; Chen, Jun; Carroll, Ian M; Ringel-Kulka, Tamar; Epstein, Michael P; Zhou, Hua; Zhou, Jin J; Ringel, Yehuda; Li, Hongzhe; Wu, Michael C

    2015-05-01

    High-throughput sequencing technology has enabled population-based studies of the role of the human microbiome in disease etiology and exposure response. Distance-based analysis is a popular strategy for evaluating the overall association between microbiome diversity and outcome, wherein the phylogenetic distance between individuals' microbiome profiles is computed and tested for association via permutation. Despite their practical popularity, distance-based approaches suffer from important challenges, especially in selecting the best distance and extending the methods to alternative outcomes, such as survival outcomes. We propose the microbiome regression-based kernel association test (MiRKAT), which directly regresses the outcome on the microbiome profiles via the semi-parametric kernel machine regression framework. MiRKAT allows for easy covariate adjustment and extension to alternative outcomes while non-parametrically modeling the microbiome through a kernel that incorporates phylogenetic distance. It uses a variance-component score statistic to test for the association with analytical p value calculation. The model also allows simultaneous examination of multiple distances, alleviating the problem of choosing the best distance. Our simulations demonstrated that MiRKAT provides correctly controlled type I error and adequate power in detecting overall association. "Optimal" MiRKAT, which considers multiple candidate distances, is robust in that it suffers from little power loss in comparison to when the best distance is used and can achieve tremendous power gain in comparison to when a poor distance is chosen. Finally, we applied MiRKAT to real microbiome datasets to show that microbial communities are associated with smoking and with fecal protease levels after confounders are controlled for.

  11. Genetic association tests for family data with missing parental genotypes: a comparison.

    Science.gov (United States)

    Whittemore, Alice S; Halpern, Jerry

    2003-07-01

    We consider three tests for genetic association in data from nuclear families (the Family-Based Association Test (FBAT) test proposed by Rabinowitz and Laird ([2000] Hum. Hered. 50:211-223), a second test proposed by Rabinowitz ([2002] J. Am. Stat. Assoc. 97:742-758), and the Family Genotype Analysis Program (FGAP) nonfounder or partial score test proposed by Clayton ([1999] Am. J. Hum. Genet. 65:1170-1177) and Whittemore and Tu ([2000] Am. J. Hum. Genet. 66:1329-1340)). We show that each test statistic arises from the efficient score of the family data as the solution to a set of constraints on its null expectation. Moreover, the FBAT and Rabinowitz tests (but not the FGAP test) are locally the most powerful among all tests satisfying their constraints. We used simulations to examine how the three tests perform in situations when their assumptions are violated and the number of families is not huge. We found that the FBAT test tended to have less power than the other two tests, particularly when applied to families in whom all offspring were affected. The Rabinowitz and FGAP tests performed similarly, although the latter tended to extract more information from families containing one typed parent. While none of the tests showed good power to detect rare, recessively acting genes, the Rabinowitz test with a sample variance estimate performed particularly poorly in this case. However, the Rabinowitz test with a model-based variance had power comparable to that of the FGAP test, and more accurate type I error rates. We conclude that for the situations we considered, the Rabinowitz test with model-based variance has good power without forfeiting robustness against misspecification of parental genotype probabilities. However, its utility is limited by the lack of a simple algorithm to apply it to families with varying structures and phenotypes.

  12. Computers and student learning: bivariate and multivariate evidence on the availability and use of computers at home and at school

    OpenAIRE

    Fuchs, Thomas; Wößmann, Ludger

    2004-01-01

    We estimate the relationship between students’ educational achievement and the availability and use of computers at home and at school in the international student-level PISA database. Bivariate analyses show a positive correlation between student achievement and the availability of computers both at home and at schools. However, once we control extensively for family background and school characteristics, the relationship gets negative for home computers and insignificant for school computer...

  13. Analysis of input variables of an artificial neural network using bivariate correlation and canonical correlation

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Valter Magalhaes; Pereira, Iraci Martinez, E-mail: valter.costa@usp.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2011-07-01

    The monitoring of variables and diagnosis of sensor fault in nuclear power plants or processes industries is very important because a previous diagnosis allows the correction of the fault and, like this, to prevent the production stopped, improving operator's security and it's not provoking economics losses. The objective of this work is to build a set, using bivariate correlation and canonical correlation, which will be the set of input variables of an artificial neural network to monitor the greater number of variables. This methodology was applied to the IEA-R1 Research Reactor at IPEN. Initially, for the input set of neural network we selected the variables: nuclear power, primary circuit flow rate, control/safety rod position and difference in pressure in the core of the reactor, because almost whole of monitoring variables have relation with the variables early described or its effect can be result of the interaction of two or more. The nuclear power is related to the increasing and decreasing of temperatures as well as the amount radiation due fission of the uranium; the rods are controls of power and influence in the amount of radiation and increasing and decreasing of temperatures; the primary circuit flow rate has the function of energy transport by removing the nucleus heat. An artificial neural network was trained and the results were satisfactory since the IEA-R1 Data Acquisition System reactor monitors 64 variables and, with a set of 9 input variables resulting from the correlation analysis, it was possible to monitor 51 variables. (author)

  14. Assessing protein conformational sampling methods based on bivariate lag-distributions of backbone angles

    KAUST Repository

    Maadooliat, Mehdi

    2012-08-27

    Despite considerable progress in the past decades, protein structure prediction remains one of the major unsolved problems in computational biology. Angular-sampling-based methods have been extensively studied recently due to their ability to capture the continuous conformational space of protein structures. The literature has focused on using a variety of parametric models of the sequential dependencies between angle pairs along the protein chains. In this article, we present a thorough review of angular-sampling-based methods by assessing three main questions: What is the best distribution type to model the protein angles? What is a reasonable number of components in a mixture model that should be considered to accurately parameterize the joint distribution of the angles? and What is the order of the local sequence-structure dependency that should be considered by a prediction method? We assess the model fits for different methods using bivariate lag-distributions of the dihedral/planar angles. Moreover, the main information across the lags can be extracted using a technique called Lag singular value decomposition (LagSVD), which considers the joint distribution of the dihedral/planar angles over different lags using a nonparametric approach and monitors the behavior of the lag-distribution of the angles using singular value decomposition. As a result, we developed graphical tools and numerical measurements to compare and evaluate the performance of different model fits. Furthermore, we developed a web-tool (http://www.stat.tamu. edu/~madoliat/LagSVD) that can be used to produce informative animations. © The Author 2012. Published by Oxford University Press.

  15. New Colors for Histology: Optimized Bivariate Color Maps Increase Perceptual Contrast in Histological Images.

    Directory of Open Access Journals (Sweden)

    Jakob Nikolas Kather

    Full Text Available Accurate evaluation of immunostained histological images is required for reproducible research in many different areas and forms the basis of many clinical decisions. The quality and efficiency of histopathological evaluation is limited by the information content of a histological image, which is primarily encoded as perceivable contrast differences between objects in the image. However, the colors of chromogen and counterstain used for histological samples are not always optimally distinguishable, even under optimal conditions.In this study, we present a method to extract the bivariate color map inherent in a given histological image and to retrospectively optimize this color map. We use a novel, unsupervised approach based on color deconvolution and principal component analysis to show that the commonly used blue and brown color hues in Hematoxylin-3,3'-Diaminobenzidine (DAB images are poorly suited for human observers. We then demonstrate that it is possible to construct improved color maps according to objective criteria and that these color maps can be used to digitally re-stain histological images.To validate whether this procedure improves distinguishability of objects and background in histological images, we re-stain phantom images and N = 596 large histological images of immunostained samples of human solid tumors. We show that perceptual contrast is improved by a factor of 2.56 in phantom images and up to a factor of 2.17 in sets of histological tumor images.Thus, we provide an objective and reliable approach to measure object distinguishability in a given histological image and to maximize visual information available to a human observer. This method could easily be incorporated in digital pathology image viewing systems to improve accuracy and efficiency in research and diagnostics.

  16. The Association between Graphomotor Tests and Participation of Typically Developing Young Children

    Science.gov (United States)

    Rosenberg, Limor

    2015-01-01

    This study aimed to explore the association between graphomotor tests--VMI, ROCF, SWT--and the measures of a child's participation. Seventy-five typically developing children aged 4 to 9 years were individually evaluated using the graphomotor tests and their parents completed a participation questionnaire. After controlling for child's age, the…

  17. A multivariate family-based association test using generalized estimating equations : FBAT-GEE

    NARCIS (Netherlands)

    Lange, C; Silverman, SK; Xu, [No Value; Weiss, ST; Laird, NM

    2003-01-01

    In this paper we propose a multivariate extension of family-based association tests based on generalized estimating equations. The test can be applied to multiple phenotypes and to phenotypic data obtained in longitudinal studies without making any distributional assumptions for the phenotypic obser

  18. A new formula for bivariate Hermite interpolation on variable step grids and its application to image interpolation.

    Science.gov (United States)

    Delibasis, Konstantinos K; Kechriniotis, Aristides

    2014-07-01

    In this paper, we present a novel formula of the bivariate Hermite interpolating (BHI) polynomial in the case of support points arranged on a grid with variable step. This expression is applicable when interpolation of a bivariate function is required, given its value and the values of its partial derivatives of arbitrarily high order, at the support points. The proposed formula is a generalization of an existing formula for the bivariate Hermite polynomial. It is also algebraically much simpler, thus can be computed more efficiently. In order to apply Hermite interpolation to image interpolation, we simplify the proposed (BHI) to handle support points on a regular unit-step grid. The values of image partial derivatives are arithmetically approximated using compact finite differences. The proposed method is being assessed in a number of image interpolation experiments that include a synthetic image, for which the values of the partial derivatives are computed analytically, as well as a collection of images from different medical modalities. The proposed BHI with up to second-order image partial derivatives, outperforms the convolution-based interpolation methods, as well as generalized interpolation methods with the same number of support points that was compared with, in the majority of image interpolation experiments. The computational load of the proposed BHI is calculated and its behaviour with respect to its controlling parameters is investigated.

  19. Meta-analysis for diagnostic accuracy studies: a new statistical model using beta-binomial distributions and bivariate copulas.

    Science.gov (United States)

    Kuss, Oliver; Hoyer, Annika; Solms, Alexander

    2014-01-15

    There are still challenges when meta-analyzing data from studies on diagnostic accuracy. This is mainly due to the bivariate nature of the response where information on sensitivity and specificity must be summarized while accounting for their correlation within a single trial. In this paper, we propose a new statistical model for the meta-analysis for diagnostic accuracy studies. This model uses beta-binomial distributions for the marginal numbers of true positives and true negatives and links these margins by a bivariate copula distribution. The new model comes with all the features of the current standard model, a bivariate logistic regression model with random effects, but has the additional advantages of a closed likelihood function and a larger flexibility for the correlation structure of sensitivity and specificity. In a simulation study, which compares three copula models and two implementations of the standard model, the Plackett and the Gauss copula do rarely perform worse but frequently better than the standard model. We use an example from a meta-analysis to judge the diagnostic accuracy of telomerase (a urinary tumor marker) for the diagnosis of primary bladder cancer for illustration.

  20. Family-Based Association Testing of OCD-associated SNPs of SLC1A1 in an autism sample.

    Science.gov (United States)

    Brune, Camille W; Kim, Soo-Jeong; Hanna, Gregory L; Courchesne, Eric; Lord, Catherine; Leventhal, Bennett L; Cook, Edwin H

    2008-04-01

    Reports identified the neuronal glutamate transporter gene, SLC1A1 (OMIM 133550, chromosome 9p24), as a positional and functional candidate gene for obsessive-compulsive disorder (OCD). The presence of obsessions and compulsions similar to OCD in autism, the identification of this region in a genome-wide linkage analysis of individuals with autism spectrum disorders (ASDs), and the hypothesized role of glutamate in ASDs make SLC1A1 a candidate gene for ASD as well. To test for association between SLC1A1 and autism, we typed three single nucleotide polymorphisms (SNPs, rs301430, rs301979, rs301434) previously associated with OCD in 86 strictly defined trios with autism. Family-Based Association Tests (FBAT) with additive and recessive models were used to check for association. Additionally, an rs301430-rs301979 haplotype identified for OCD was investigated. FBAT revealed nominally significant association between autism and one SNP under a recessive model. The G allele of rs301979 was undertransmitted (equivalent to overtransmission of the C allele under a dominant model) to individuals with autism (Z=-2.47, P=0.01). The G allele was also undertransmitted in the T-G haplotype under the recessive model (Z=-2.41, P=0.02). Both findings were also observed in the male-only sample. However, they did not withstand correction for multiple comparisons.

  1. Long-lead station-scale prediction of hydrological droughts in South Korea based on bivariate pattern-based downscaling

    Science.gov (United States)

    Sohn, Soo-Jin; Tam, Chi-Yung

    2016-05-01

    Capturing climatic variations in boreal winter to spring (December-May) is essential for properly predicting droughts in South Korea. This study investigates the variability and predictability of the South Korean climate during this extended season, based on observations from 60 station locations and multi-model ensemble (MME) hindcast experiments (1983/1984-2005/2006) archived at the APEC Climate Center (APCC). Multivariate empirical orthogonal function (EOF) analysis results based on observations show that the first two leading modes of winter-to-spring precipitation and temperature variability, which together account for ~80 % of the total variance, are characterized by regional-scale anomalies covering the whole South Korean territory. These modes were also closely related to some of the recurrent large-scale circulation changes in the northern hemisphere during the same season. Consistent with the above, examination of the standardized precipitation evapotranspiration index (SPEI) indicates that drought conditions in South Korea tend to be accompanied by regional-to-continental-scale circulation anomalies over East Asia to the western north Pacific. Motivated by the aforementioned findings on the spatial-temporal coherence among station-scale precipitation and temperature anomalies, a new bivariate and pattern-based downscaling method was developed. The novelty of this method is that precipitation and temperature data were first filtered using multivariate EOFs to enhance their spatial-temporal coherence, before being linked to large-scale circulation variables using canonical correlation analysis (CCA). To test its applicability and to investigate its related potential predictability, a perfect empirical model was first constructed with observed datasets as predictors. Next, a model output statistics (MOS)-type hybrid dynamical-statistical model was developed, using products from nine one-tier climate models as inputs. It was found that, with model sea

  2. Testing for direct genetic effects using a screening step in family-based association studies

    Directory of Open Access Journals (Sweden)

    Sharon M Lutz

    2013-11-01

    Full Text Available In genome wide association studies (GWAS, families based studies tend to have less power to detect genetic associations than population based studies, such as case-control studies. This can be an issue when testing if genes in a family based GWAS have a direct effect on the phenotype of interest or if the genes act indirectly through a secondary phenotype. When multiple SNPs are tested for a direct effect in the family based study, a screening step can be used to minimize the burden of multiple comparisons in the causal analysis. We propose a 2-stage screening step that can be incorporated into the family based association test (FBAT approach similar to the conditional mean model approach in the VanSteen-algorithm [1]. Simulations demonstrate that the type 1 error is preserved and this method is advantageous when multiple markers are tested. This method is illustrated by an application to the Framingham Heart Study.

  3. A robust TDT-type association test under informative parental missingness.

    Science.gov (United States)

    Chen, J H; Cheng, K F

    2011-02-10

    Many family-based association tests rely on the random transmission of alleles from parents to offspring. Among them, the transmission/disequilibrium test (TDT) may be considered to be the most popular statistical test. The TDT statistic and its variations were proposed to evaluate nonrandom transmission of alleles from parents to the diseased children. However, in family studies, parental genotypes may be missing due to parental death, loss, divorce, or other reasons. Under some missingness conditions, nonrandom transmission of alleles may still occur even when the gene and disease are not associated. As a consequence, the usual TDT-type tests would produce excessive false positive conclusions in association studies. In this paper, we propose a novel TDT-type association test which is not only simple in computation but also robust to the joint effect of population stratification and informative parental missingness. Our test is model-free and allows for different mechanisms of parental missingness across subpopulations. We use a simulation study to compare the performance of the new test with TDT and point out the advantage of the new method.

  4. A fast multilocus test with adaptive SNP selection for large-scale genetic-association studies

    KAUST Repository

    Zhang, Han

    2013-09-11

    As increasing evidence suggests that multiple correlated genetic variants could jointly influence the outcome, a multilocus test that aggregates association evidence across multiple genetic markers in a considered gene or a genomic region may be more powerful than a single-marker test for detecting susceptibility loci. We propose a multilocus test, AdaJoint, which adopts a variable selection procedure to identify a subset of genetic markers that jointly show the strongest association signal, and defines the test statistic based on the selected genetic markers. The P-value from the AdaJoint test is evaluated by a computationally efficient algorithm that effectively adjusts for multiple-comparison, and is hundreds of times faster than the standard permutation method. Simulation studies demonstrate that AdaJoint has the most robust performance among several commonly used multilocus tests. We perform multilocus analysis of over 26,000 genes/regions on two genome-wide association studies of pancreatic cancer. Compared with its competitors, AdaJoint identifies a much stronger association between the gene CLPTM1L and pancreatic cancer risk (6.0 × 10(-8)), with the signal optimally captured by two correlated single-nucleotide polymorphisms (SNPs). Finally, we show AdaJoint as a powerful tool for mapping cis-regulating methylation quantitative trait loci on normal breast tissues, and find many CpG sites whose methylation levels are jointly regulated by multiple SNPs nearby.

  5. Prevalence of condomless anal intercourse and recent HIV testing and their associated factors among men who have sex with men in Hangzhou, China: A respondent-driven sampling survey

    Science.gov (United States)

    Pan, Xiaohong; Ma, Qiaoqin; Chen, Lin; Zhou, Xin; Jiang, Tingting; He, Lin; Chen, Junfang; Zhang, Xingliang; Luo, Yan; Xi, Shengjun; Lv, Xin; Xia, Shichang

    2017-01-01

    Men who have sex with men (MSM) are a large high-risk population for HIV infection in recent years in China. A cross-sectional survey was conducted in Hangzhou, China, to determine rates of condomless anal intercourse (CAI), recent HIV testing (in the recent year) and associated factors using respondent-driven sampling. Questionnaires using face-to-face interviews were employed to collect data on sexual risk behaviors and HIV testing. Five hundred eleven MSM were recruited, of which 459 (89.8%) had anal intercourse in the past 6 months. Of these 459 participants, 457 (99.6%) answered whether they had taken an HIV test in the recent year, so only their data were analyzed. Weighted data were analyzed using bivariate and multivariate logistic regression analysis. The CAI rate with male partners in the past 6 months was 43.7% (95% confidence interval [CI], 34.0–51.5%), while the rate of condomless vaginal intercourse (CVI) was 21.6% (95% CI, 15.6–32.3%). The prevalence of recent HIV testing was 56.8% (95% CI, 48.7–66.5%), while the prevalence of HIV and syphilis were 8.8% and 6.5%, respectively. Multivariate analysis indicated that CAI was associated with earlier homosexual debut, suicidal inclinations, childhood sexual abuse, HIV testing in the recent year, and lower estimate of HIV prevalence. Recent HIV testing was associated with homosexual debut age, engaging in CAI with male partners in the past 6 months, having oral sex in the past 6 months, self-perceived higher likelihood of HIV infection, knowing about antiretroviral therapy for HIV/AIDS, receiving AIDS/sexually transmitted infection (STI) interventions in the past year, and syphilis infection. Given high prevalence of HIV and syphilis, high levels of CAI and CVI, and low HIV testing rate, the results indicated high risk of HIV infection and transmission among MSM. HIV prevention interventions should target MSM with early homosexual debut and psychosocial health problems, while HIV/AIDS education among

  6. The association between methacholine challenge test and respiratory symptoms: a study on 146 patients

    Directory of Open Access Journals (Sweden)

    Paknejad O

    2011-02-01

    Full Text Available "nBackground: Asthma is a life-threatening disease that can cause death due to bronchospasm. In addition to clinical symptoms such as wheezing, acute paroxysmal dyspnea, chronic cough after exposure to cold air or cough after exercise, spirometry is also necessary for the diagnosis of asthma. The association between respiratory symptoms and a positive methacholine challenge test (MCT is still controversial. The aim of this study was to determine the association between methacholine test results and respiratory symptoms and allergy."n "nMethods: One hundred and forty-six patients with respiratory symptoms and normal baseline pulmonary function tests were enrolled in this cross-sectional study. The participants were divided into two groups according to their positive or negative response to MCT. The association between MCT and the clinical symptoms and allergy was later evaluated statistically."n "nResults: Out of 146 participants of the study 59 (40.4% were female and 87 (59.6% were male. The mean age of the participants was 33.8±13.8 years. Sixty-one patients (41.8% had positive results for the test. There was an association between a history of allergy, wheezing and age with positive MCT results. The other clinical signs had no association with the test."n "nConclusion: Methacholine challenge test is the best diagnostic test for ruling out asthma in patients with normal pulmonary function tests in whom we cannot definitely rule out asthma based solely on clinical symptoms. Nevertheless, in adults with a history of allergy, wheezing and also in patients below 30, the probability for a positive MCT is high.

  7. Suggestions from Representatives of the International Language Testing Association for Revision of the "AERA/APA/NCME Standards for Educational and Psychological Testing."

    Science.gov (United States)

    Stansfield, Charles W.; Spolsky, Bernard

    The International Language Testing Association has some 250 members in 15 countries. Most are specialists in the testing of second language skills, with a special interest in performance assessment because of the testing of speaking and writing performance that is critical to second language skills assessment. The association believes that certain…

  8. Association between positive patch tests to epoxy resin and fragrance mix I ingredients

    DEFF Research Database (Denmark)

    Andersen, Klaus Ejner; Christensen, Lars Porskjaer; Vølund, Aage;

    2009-01-01

    BACKGROUND: Both epoxy resin (diglycidyl ether of bisphenol A) and fragrance mix I are included in the European baseline series of contact allergens. A significant association between positive reactions to epoxy resin and fragrance mix has been reported by others. OBJECTIVE: To investigate...... were included, and test results from all patients tested with fragrance mix ingredients were analysed. RESULTS: One hundred and forty-five (2.4%) were positive to epoxy resin and 282 (4.6%) were positive to fragrance mix I. Nineteen were positive to both giving an odds ratio of 3.3, which...... is significant (95% CI 2.0-5.4). Analysis of association to individual fragrance mix ingredients showed a significant association to alpha-amyl cinnamal and isoeugenol. CONCLUSIONS: The significant association between positive reactions to epoxy resin and fragrance mix I was reproduced. However, the clinical...

  9. Increasing genotype-phenotype model determinism: application to bivariate reading/language traits and epistatic interactions in language-impaired families.

    Science.gov (United States)

    Simmons, Tabatha R; Flax, Judy F; Azaro, Marco A; Hayter, Jared E; Justice, Laura M; Petrill, Stephen A; Bassett, Anne S; Tallal, Paula; Brzustowicz, Linda M; Bartlett, Christopher W

    2010-01-01

    While advances in network and pathway analysis have flourished in the era of genome-wide association analysis, understanding the genetic mechanism of individual loci on phenotypes is still readily accomplished using genetic modeling approaches. Here, we demonstrate two novel genotype-phenotype models implemented in a flexible genetic modeling platform. The examples come from analysis of families with specific language impairment (SLI), a failure to develop normal language without explanatory factors such as low IQ or inadequate environment. In previous genome-wide studies, we observed strong evidence for linkage to 13q21 with a reading phenotype in language-impaired families. First, we elucidate the genetic architecture of reading impairment and quantitative language variation in our samples using a bivariate analysis of reading impairment in affected individuals jointly with language quantitative phenotypes in unaffected individuals. This analysis largely recapitulates the baseline analysis using the categorical trait data (posterior probability of linkage (PPL) = 80%), indicating that our reading impairment phenotype captured poor readers who also have low language ability. Second, we performed epistasis analysis using a functional coding variant in the brain-derived neurotrophic factor (BDNF) gene previously associated with reduced performance on working memory tasks. Modeling epistasis doubled the evidence on 13q21 and raised the PPL to 99.9%, indicating that BDNF and 13q21 susceptibility alleles are jointly part of the genetic architecture of SLI. These analyses provide possible mechanistic insights for further cognitive neuroscience studies based on the models developed herein.

  10. Test Methods and Protocols for Environmental and Safety Hazards Associated with Home Energy Retrofits

    Energy Technology Data Exchange (ETDEWEB)

    Cautley, D. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Viner, J. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Lord, M. [NorthernSTAR Building America Partnership, St. Paul, MN (United States); Pearce, M. [NorthernSTAR Building America Partnership, St. Paul, MN (United States)

    2012-12-01

    A number of health hazards and hazards to the durability of homes may be associated with energy retrofitting and home renovation projects. Among the hazards associated with energy retrofit work, exposure to radon is thought to cause more than 15,000 deaths per year in the U.S., while carbon monoxide poisoning results in about 20,000 injuries and 450 deaths per year. Testing procedures have been developed for identifying and quantifying hazards during retrofitting. These procedures commonly include a battery of tests to screen combustion appliances for safe operation, including worst case depressurization measurement, backdrafting (spillage) under depressurized or normal conditions, and carbon monoxide production.

  11. Generalizing Terwilliger's likelihood approach: a new score statistic to test for genetic association

    OpenAIRE

    Hsu Li; Helmer Quinta; de Visser Marieke CH; Uitte de Willige Shirley; el Galta Rachid; Houwing-Duistermaat Jeanine J

    2007-01-01

    Abstract Background: In this paper, we propose a one degree of freedom test for association between a candidate gene and a binary trait. This method is a generalization of Terwilliger's likelihood ratio statistic and is especially powerful for the situation of one associated haplotype. As an alternative to the likelihood ratio statistic, we derive a score statistic, which has a tractable expression. For haplotype analysis, we assume that phase is known. Results: By means of a simulation study...

  12. Psychological distress and quality of life associated with genetic testing for breast cancer risk.

    Science.gov (United States)

    Smith, Ashley Wilder; Dougall, Angela Liegey; Posluszny, Donna M; Somers, Tamara J; Rubinstein, Wendy S; Baum, Andrew

    2008-08-01

    This study investigated short- and long-term psychological outcomes associated with BRCA1/2 genetic testing in women with a personal or family history of breast cancer. Participants included 126 women considering genetic testing. Questionnaires were administered prior to testing, one week, three and six months after result disclosure. Results indicated no systematic effects of testing based on personal cancer history. Mutation carriers and women who elected not to be tested reported greater perceived risk and intrusive and avoidant thoughts at follow-up time points than did women who received negative (uninformative) or variant results. Mutation carriers reported more distress at the three-month follow-up but by six months the effects of test result on distress dissipated and groups were comparable. Cluster analyses identified two groups of individuals based on distress at baseline; these groups were used to predict psychological outcomes after testing. Distress remained constant in both groups: those who were high at baseline remained high and those who were low remained low. Test results did not moderate this effect. Results suggest that genetic testing for BRCA1/2 does not increase distress or have deleterious effects on quality of life over the long term. However, sub-groups of women may report more distress over time. These data indicate the need for more targeted counseling to individuals who report high levels of distress when considering genetic testing.

  13. Associations between Benzodiazepine Use and Neuropsychological Test Scores in Older Adults.

    Science.gov (United States)

    Helmes, Edward; Østbye, Truls

    2015-06-01

    Benzodiazepines are widely prescribed for anxiety, although use of this class of medications has been associated with dependency and cognitive changes. This article describes the study in which we investigated the relationship between the class of benzodiazepine available for use and associated performance on neuropsychological tests in a community sample of 1,754 older Canadians from the Canadian Study of Health and Aging. Benzodiazepines were classified as short-, intermediate-, and long-acting. Associations were calculated between each class of benzodiazepine and eight neuropsychological measures, using multiple regression analysis and controlling for demographic variables. Results showed different effects of the co-variates across the three drug classes, and short half-life benzodiazepines were not associated with any neuropsychological measure. Intermediate half-life and long half-life benzodiazepine use were each associated with two measures. Increased focus on specific domains of cognitive function is needed to improve our understanding of how benzodiazepine use influences cognition.

  14. Impairment of Self-control and its manifestations in Continuous Word Association Test

    Directory of Open Access Journals (Sweden)

    Gabriela Marhevská

    2013-01-01

    Full Text Available The aim of work is to find out how self–control influences word associations. The research presented herein provides new insight into manifestations of self–control. Experimental study is based on the Strength model (Baumeister, Bratslavsky, Muraven, & Tice, 1998, which assumes that self–control relies on limited resources of ego which become depleted with increased exercising of self–control (Ego depletion. The aim of this experiment was to verify in an empirical manner that the impairment of self–control can be manifested in word association tests. Continuous word association test (Kondáš, 1979 was used in this experiment. Distinct indicators of continuous word associations were divided into the following 4 categories; verbal dynamics, abnormalities in association, errors in the reproduction of association reactions and the overall number of mistakes. Parallel task and “e letter” crossing out exercises were used in order to impair ego resource.One–Way ANOVA was used in the analysis. The results of the study indicate that impaired self–control, induced by the “e letter” crossing out task, increased verbal dynamics. According to the obtained results, Continuous word association test provoke automatic processes. Further important indicators of impaired self–control were increased perseverations of potentially conflicting word ′control′, erroneous reproductions of potentially conflicting word ′explosions′ and the overall indicator of mistakes in conflict word‚ explosions and control‘. The experiment results show an increase in the number of mistakes of word association production when self–control is impaired.

  15. Multi-locus Test and Correction for Confounding Effects in Genome-Wide Association Studies.

    Science.gov (United States)

    Chen, Donglai; Liu, Chuanhai; Xie, Jun

    2016-11-01

    Genome-wide association studies (GWAS) examine a large number of genetic variants, e. g., single nucleotide polymorphisms (SNP), and associate them with a disease of interest. Traditional statistical methods for GWASs can produce spurious associations, due to limited information from individual SNPs and confounding effects. This paper develops two statistical methods to enhance data analysis of GWASs. The first is a multiple-SNP association test, which is a weighted chi-square test derived for big contingency tables. The test assesses combinatorial effects of multiple SNPs and improves conventional methods of single SNP analysis. The second is a method that corrects for confounding effects, which may come from population stratification as well as other ambiguous (unknown) factors. The proposed method identifies a latent confounding factor, using a profile of whole genome SNPs, and eliminates confounding effects through matching or stratified statistical analysis. Simulations and a GWAS of rheumatoid arthritis demonstrate that the proposed methods dramatically remove the number of significant tests, or false positives, and outperforms other available methods.

  16. Testing key predictions of the associative account of mirror neurons in humans using multivariate pattern analysis.

    Science.gov (United States)

    Oosterhof, Nikolaas N; Wiggett, Alison J; Cross, Emily S

    2014-04-01

    Cook et al. overstate the evidence supporting their associative account of mirror neurons in humans: most studies do not address a key property, action-specificity that generalizes across the visual and motor domains. Multivariate pattern analysis (MVPA) of neuroimaging data can address this concern, and we illustrate how MVPA can be used to test key predictions of their account.

  17. Can Functional Capacity Tests Predict Future Work Capacity in Patients With Whiplash-Associated Disorders?

    NARCIS (Netherlands)

    Trippolini, Maurizio A.; Dijkstra, Pieter U.; Cote, Pierre; Scholz-Odermatt, Stefan M.; Geertzen, J.H.B.; Reneman, Michiel F.

    2014-01-01

    Objective: To determine whether functional capacity evaluation (FCE) tests predict future work capacity (WC) of patients with whiplash-associated disorders (WADs) grades I and II who did not regain full WC 6 to 12 weeks after injury. Design: Prospective cohort study. Setting: Rehabilitation center.

  18. Reactions to the Implicit Association Test as an Educational Tool: A Mixed Methods Study

    Science.gov (United States)

    Hillard, Amy L.; Ryan, Carey S.; Gervais, Sarah J.

    2013-01-01

    We examined reactions to the Race Implicit Association Test (IAT), which has been widely used but rarely examined as an educational tool to raise awareness about racial bias. College students (N = 172) were assigned to read that the IAT reflected either personal beliefs or both personal and extrapersonal factors (single vs. multiple explanation…

  19. Predicting Success Using HESI A2 Entrance Tests in an Associate Degree Nursing Program

    Science.gov (United States)

    Bodman, Susan

    2012-01-01

    A challenge presented to nurse educators is retention of nursing students. This has led nursing faculty to review admission requirements and question how well entrance tests predict success in Associate Degree Nursing Programs. The purpose of this study was to investigate the relationship between the HESI Admission Assessment Exam (HESI A2) and…

  20. Prevalence of Human Immunodeficiency Virus Testing and Associated Risk Factors in College Students

    Science.gov (United States)

    Dennison, Olivia; Wu, Qishan; Ickes, Melinda

    2014-01-01

    Objective: This study documents the prevalence of human immunodeficiency virus (HIV) testing in a sample of college students and examines associated demographic and behavioral characteristics. Participants: College students aged 18 or older were randomly selected to participate in a health behavior survey at a southeastern university in September…

  1. "CONGENTIAL PANHYPOPITUITARISM ASSOCIATED WITH IMPAIRED LIVER FUNCTION TESTS AND CONGENITAL HEART DISEASE"

    Directory of Open Access Journals (Sweden)

    Z. Khalili-Matinzadeh

    2006-06-01

    Full Text Available The term congenital hypopituitarism defines deficiency of all of the pituitary hormones. Hypoglycemia and microphallus (in males are common findings, and some infants have shown evidence of the neonatal hepatitis syndrome. We report a case of congenital panhypopituitarism with deficiency of six major hormones and association with severe hypoglycemia, impaired liver function tests and congenital heart disease.

  2. Using the Implicit Association Test as an Unconsciousness Raising Tool in Psychology

    Science.gov (United States)

    Casad, Bettina J.; Flores, Abdiel J.; Didway, Jessica D.

    2013-01-01

    People are reluctant to admit they harbor implicit biases. Students (N = 68) from four social psychology courses completed an assignment designed to raise awareness about implicit biases. After completing an Implicit Association Test (IAT), students answered six essay questions, read two articles on the IAT, and answered five additional essay…

  3. The Implicit Association Test as a Class Assignment: Student Affective and Attitudinal Reactions

    Science.gov (United States)

    Morris, Kathryn A.; Ashburn-Nardo, Leslie

    2010-01-01

    The Implicit Association Test (IAT) is a popular means of examining "hidden" biases. However, some express concerns about classroom use of the IAT, citing students' potentially negative affective reactions to taking the IAT and discovering their implicit biases. To investigate the validity of this criticism, 35 social psychology students completed…

  4. [Factors associated with failure to take a Pap smear test among Quilombola women].

    Science.gov (United States)

    Oliveira, Márcio Vasconcelos; Guimarães, Mark Drew Crosland; França, Elisabeth Barboza

    2014-11-01

    The objective of this study was to analyze factors associated with failure to take a Pap smear test among quilombola women living in Vitória da Conquista in the state of Bahia. A cross-sectional, population-based study was conducted with women aged 18 to 64. Descriptive analysis and univariate and multivariate analysis using a multinomial logistic model was applied. Women who had never performed the test or had not had one for over three years were compared separately from those who were examined within the preceding three years. Of the 348 women included in the analysis, 27.3%, reported never having a Pap smear test. The following factors were independently associated with never having taken the test: age of 18 to 29 years and 50 to 59 years; lack of education; not having a partner; seeking care in health-related units/establishments other than their place of residence; and having a clinical breast examination three or more years ago or never having one. The findings indicate a need for reflection in order to combat factors that are associated with not having a Pap smear test among quilombola women, since it is important to implement actions for the prevention of cervical cancer.

  5. The single category implicit association test as a measure of implicit social cognition.

    Science.gov (United States)

    Karpinski, Andrew; Steinman, Ross B

    2006-07-01

    The Single Category Implicit Association Test (SC-IAT) is a modification of the Implicit Association Test that measures the strength of evaluative associations with a single attitude object. Across 3 different attitude domains--soda brand preferences, self-esteem, and racial attitudes--the authors found evidence that the SC-IAT is internally consistent and makes unique contributions in the ability to understand implicit social cognition. In a 4th study, the authors investigated the susceptibility of the SC-IAT to faking or self-presentational concerns. Once participants with high error rates were removed, no significant self-presentation effect was observed. These results provide initial evidence for the reliability and validity of the SC-IAT as an individual difference measure of implicit social cognition.

  6. Are MMSE and HDS-R neuropsychological tests adequate for screening HIV-associated neurocognitive disorders?

    Science.gov (United States)

    Nakazato, Ai; Tominaga, Daisuke; Tasato, Daisuke; Miyagi, Kyoko; Nakamura, Hideta; Haranaga, Shusaku; Higa, Futoshi; Tateyama, Masao; Fujita, Jiro

    2014-03-01

    HIV-associated neurocognitive disorders (HAND) are one of major comorbidities in patients with HIV-1 infection. There are currently no standardized tests for screening HAND in such patients. The sensitivity of the cognitive function tests routinely used in clinical practice, such as the Mini-Mental State Examination and the Revised Hasegawa's Dementia Scale, is inadequate to rule out HAND, even in patients with clear abnormal behavior. We report a 41-year-old man with HIV-associated dementia, the most severe form of HAND, in whom the simplified methods did not show abnormal results, and a comprehensive battery of neuropsychological tests which covering several cognitive domains was needed to detect cognitive impairment.

  7. Testing pairwise association between spatially autocorrelated variables: a new approach using surrogate lattice data.

    Directory of Open Access Journals (Sweden)

    Vincent Deblauwe

    Full Text Available BACKGROUND: Independence between observations is a standard prerequisite of traditional statistical tests of association. This condition is, however, violated when autocorrelation is present within the data. In the case of variables that are regularly sampled in space (i.e. lattice data or images, such as those provided by remote-sensing or geographical databases, this problem is particularly acute. Because analytic derivation of the null probability distribution of the test statistic (e.g. Pearson's r is not always possible when autocorrelation is present, we propose instead the use of a Monte Carlo simulation with surrogate data. METHODOLOGY/PRINCIPAL FINDINGS: The null hypothesis that two observed mapped variables are the result of independent pattern generating processes is tested here by generating sets of random image data while preserving the autocorrelation function of the original images. Surrogates are generated by matching the dual-tree complex wavelet spectra (and hence the autocorrelation functions of white noise images with the spectra of the original images. The generated images can then be used to build the probability distribution function of any statistic of association under the null hypothesis. We demonstrate the validity of a statistical test of association based on these surrogates with both actual and synthetic data and compare it with a corrected parametric test and three existing methods that generate surrogates (randomization, random rotations and shifts, and iterative amplitude adjusted Fourier transform. Type I error control was excellent, even with strong and long-range autocorrelation, which is not the case for alternative methods. CONCLUSIONS/SIGNIFICANCE: The wavelet-based surrogates are particularly appropriate in cases where autocorrelation appears at all scales or is direction-dependent (anisotropy. We explore the potential of the method for association tests involving a lattice of binary data and discuss its

  8. Testing Pairwise Association between Spatially Autocorrelated Variables: A New Approach Using Surrogate Lattice Data

    Science.gov (United States)

    Deblauwe, Vincent; Kennel, Pol; Couteron, Pierre

    2012-01-01

    Background Independence between observations is a standard prerequisite of traditional statistical tests of association. This condition is, however, violated when autocorrelation is present within the data. In the case of variables that are regularly sampled in space (i.e. lattice data or images), such as those provided by remote-sensing or geographical databases, this problem is particularly acute. Because analytic derivation of the null probability distribution of the test statistic (e.g. Pearson's r) is not always possible when autocorrelation is present, we propose instead the use of a Monte Carlo simulation with surrogate data. Methodology/Principal Findings The null hypothesis that two observed mapped variables are the result of independent pattern generating processes is tested here by generating sets of random image data while preserving the autocorrelation function of the original images. Surrogates are generated by matching the dual-tree complex wavelet spectra (and hence the autocorrelation functions) of white noise images with the spectra of the original images. The generated images can then be used to build the probability distribution function of any statistic of association under the null hypothesis. We demonstrate the validity of a statistical test of association based on these surrogates with both actual and synthetic data and compare it with a corrected parametric test and three existing methods that generate surrogates (randomization, random rotations and shifts, and iterative amplitude adjusted Fourier transform). Type I error control was excellent, even with strong and long-range autocorrelation, which is not the case for alternative methods. Conclusions/Significance The wavelet-based surrogates are particularly appropriate in cases where autocorrelation appears at all scales or is direction-dependent (anisotropy). We explore the potential of the method for association tests involving a lattice of binary data and discuss its potential for

  9. Association between physiological falls risk and physical performance tests among community-dwelling older adults

    Directory of Open Access Journals (Sweden)

    Singh DK

    2015-08-01

    Full Text Available Devinder KA Singh,1 Sharmila GK Pillai,1 Sin Thien Tan,1 Chu Chiau Tai,1 Suzana Shahar2 1Physiotherapy Programme, School of Rehabilitation Sciences, 2Nutrition and Dietetics Programme, School of Healthcare Sciences, Faculty of Health Sciences, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, Kuala Lumpur, Malaysia Background: Physical performance and balance declines with aging and may lead to increased risk of falls. Physical performance tests may be useful for initial fall-risk screening test among community-dwelling older adults. Physiological profile assessment (PPA, a composite falls risk assessment tool is reported to have 75% accuracy to screen for physiological falls risk. PPA correlates with Timed Up and Go (TUG test. However, the association between many other commonly used physical performance tests and PPA is not known. The aim of the present study was to examine the association between physiological falls risk measured using PPA and a battery of physical performance tests.Methods: One hundred and forty older adults from a senior citizens club in Kuala Lumpur, Malaysia (94 females, 46 males, aged 60 years and above (65.77±4.61, participated in this cross-sectional study. Participants were screened for falls risk using PPA. A battery of physical performance tests that include ten-step test (TST, short physical performance battery (SPPB, functional reach test (FRT, static balance test (SBT, TUG, dominant hand-grip strength (DHGS, and gait speed test (GST were also performed. Spearman’s rank correlation and binomial logistic regression were performed to examine the significantly associated independent variables (physical performance tests with falls risk (dependent variable.Results: Approximately 13% older adults were at high risk of falls categorized using PPA. Significant differences (P<0.05 were demonstrated for age, TST, SPPB, FRT, SBT, TUG between high and low falls risk group. A significant (P<0.01 weak correlation

  10. The associations between adolescent sleep, diurnal cortisol patterns and cortisol reactivity to dexamethasone suppression test.

    Science.gov (United States)

    Pesonen, Anu-Katriina; Martikainen, Silja; Kajantie, Eero; Heinonen, Kati; Wehkalampi, Karoliina; Lahti, Jari; Strandberg, Timo; Räikkönen, Katri

    2014-11-01

    Information on the associations between objectively measured sleep and hypothalamic-pituitary-adrenal axis function in early adolescence is scarce. We examined associations between average sleep duration and quality (sleep efficiency and wake after sleep onset) over 8 days with actigraphs and (1) diurnal cortisol patterns and (2) cortisol reactivity to a low-dose (3 μg/kg) overnight dexamethasone suppression test (DST) in a birth cohort born in 1998 (N=265 participants, mean age 12.3 years, SD=0.5). We also explored (3) if sleep duration and quality were affected the nights after the DST exposure. Cortisol was measured during 2 days, and participants were exposed to dexamethasone in the evening of first day. In boys, short sleep duration was associated with higher cortisol upon awakening and lower cortisol awakening response (CAR; Psleep duration in boys associated with higher CAR (Psleep quality in boys associated with lower CAR, but fell slightly short of significance (PSleep quantity and quality were not associated with responses to the DST. There were no effects of DST on sleep (P>0.15 in between-subject analyses). The average sleep patterns showed associations with diurnal cortisol patterns during early adolescence, but only in boys. Sleep was not associated with cortisol reactivity to DST and the exogenous corticosteroid exposure did not affect sleep significantly.

  11. Factors associated with medical student test anxiety in objective structured clinical examinations: a preliminary study

    Science.gov (United States)

    2016-01-01

    Objectives To investigate attributes of medical students associated with their test anxiety on Objective Structured Clinical Examinations (OSCEs). Methods A cross-sectional study using a self-administered questionnaire was conducted of all Year 3 and 4 students at a private medical school in South Korea in 2014. This 53-item questionnaire consisted of factors pertaining to test anxiety on the OSCE identified from a review of relevant literature, which included students’ motivational beliefs and achievement emotions, perceived values of the OSCE, and attitude and orientation towards patients. Participants’ test anxiety levels were measured using the Korean Achievement Emotions Questionnaire. Participants rated their responses using a five-point Likert-type scale. Univariate analysis was performed to examine relationships between the variables. Results A total of 94 students completed the questionnaire (a 93% response rate). No differences in the participants’ test anxiety scores were observed across genders, entry-levels, or years in medical school. Participants’ test anxiety on the OSCE showed moderate association with their class-related achievement emotions (i.e., anxiety and boredom), where r = 0.46 and 0.32, p OSCE (r = -0.21, p OSCE. These findings have implications for developing effective educational interventions for helping students cope with such a stress by enhancing our understanding of the various factors that influence their test anxiety in OSCEs. PMID:28035056

  12. Evaluating the impact of genotype errors on rare variant tests of association.

    Science.gov (United States)

    Cook, Kaitlyn; Benitez, Alejandra; Fu, Casey; Tintle, Nathan

    2014-01-01

    The new class of rare variant tests has usually been evaluated assuming perfect genotype information. In reality, rare variant genotypes may be incorrect, and so rare variant tests should be robust to imperfect data. Errors and uncertainty in SNP genotyping are already known to dramatically impact statistical power for single marker tests on common variants and, in some cases, inflate the type I error rate. Recent results show that uncertainty in genotype calls derived from sequencing reads are dependent on several factors, including read depth, calling algorithm, number of alleles present in the sample, and the frequency at which an allele segregates in the population. We have recently proposed a general framework for the evaluation and investigation of rare variant tests of association, classifying most rare variant tests into one of two broad categories (length or joint tests). We use this framework to relate factors affecting genotype uncertainty to the power and type I error rate of rare variant tests. We find that non-differential genotype errors (an error process that occurs independent of phenotype) decrease power, with larger decreases for extremely rare variants, and for the common homozygote to heterozygote error. Differential genotype errors (an error process that is associated with phenotype status), lead to inflated type I error rates which are more likely to occur at sites with more common homozygote to heterozygote errors than vice versa. Finally, our work suggests that certain rare variant tests and study designs may be more robust to the inclusion of genotype errors. Further work is needed to directly integrate genotype calling algorithm decisions, study costs and test statistic choices to provide comprehensive design and analysis advice which appropriately accounts for the impact of genotype errors.

  13. Cognitive factors associated with the willingness for HIV testing among pregnant women in China

    Institute of Scientific and Technical Information of China (English)

    Li Chunrong; Yang Liu; Kong Jinwang

    2014-01-01

    Background The spread of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) epidemic in the worldwide trend is not contained effectively.The pregnant women infected HIV seriously in the high HIV epidemic areas in China.The transmission of HIV to child may be cut off if HIV positive mother was found early by HIV testing.Pregnant women mandatorily received the HIV counseling and testing services.Most of them did not know the knowledge about HIV prevention and were not willing to receive HIV testing actively.Willingness for HIV testing among pregnant women was investigated,which can help to promote them to take up HIV testing actively.This study assessed the prevalence of the willingness for HIV testing and cognitive factors associated with it.Methods A cross-sectional survey was conducted to 500 pregnant women via face-to-face interviews with anonymous structured questionnaire guided by the Health Belief Model (HBM).Results The prevalence of the willingness for HIV testing was 58.60%.Perceived higher susceptibility to HIV (multivariateadjusted odds ratio (ORm)=2.02,95% confidence interval (CI):1.40-5.06),more knowledge for HIV (ORm=1.92,95% CI:1.11-3.87) and perceived less social stigma (ORm=0.80,95% CI:0.34-0.91) were associated with higher willingness for HIV testing among pregnant women.Conclusion To prevent HIV mother to children transmission,it is necessary to enhance knowledge for HIV,change cognitive factors and increase willingness for HIV testing among pregnant women.

  14. Assessing the impact of differential genotyping errors on rare variant tests of association.

    Science.gov (United States)

    Mayer-Jochimsen, Morgan; Fast, Shannon; Tintle, Nathan L

    2013-01-01

    Genotyping errors are well-known to impact the power and type I error rate in single marker tests of association. Genotyping errors that happen according to the same process in cases and controls are known as non-differential genotyping errors, whereas genotyping errors that occur with different processes in the cases and controls are known as differential genotype errors. For single marker tests, non-differential genotyping errors reduce power, while differential genotyping errors increase the type I error rate. However, little is known about the behavior of the new generation of rare variant tests of association in the presence of genotyping errors. In this manuscript we use a comprehensive simulation study to explore the effects of numerous factors on the type I error rate of rare variant tests of association in the presence of differential genotyping error. We find that increased sample size, decreased minor allele frequency, and an increased number of single nucleotide variants (SNVs) included in the test all increase the type I error rate in the presence of differential genotyping errors. We also find that the greater the relative difference in case-control genotyping error rates the larger the type I error rate. Lastly, as is the case for single marker tests, genotyping errors classifying the common homozygote as the heterozygote inflate the type I error rate significantly more than errors classifying the heterozygote as the common homozygote. In general, our findings are in line with results from single marker tests. To ensure that type I error inflation does not occur when analyzing next-generation sequencing data careful consideration of study design (e.g. use of randomization), caution in meta-analysis and using publicly available controls, and the use of standard quality control metrics is critical.

  15. Nonlinear bivariate dependency of price-volume relationships in agricultural commodity futures markets: A perspective from Multifractal Detrended Cross-Correlation Analysis

    Science.gov (United States)

    He, Ling-Yun; Chen, Shu-Peng

    2011-01-01

    Nonlinear dependency between characteristic financial and commodity market quantities (variables) is crucially important, especially between trading volume and market price. Studies on nonlinear dependency between price and volume can provide practical insights into market trading characteristics, as well as the theoretical understanding of market dynamics. Actually, nonlinear dependency and its underlying dynamical mechanisms between price and volume can help researchers and technical analysts in understanding the market dynamics by integrating the market variables, instead of investigating them in the current literature. Therefore, for investigating nonlinear dependency of price-volume relationships in agricultural commodity futures markets in China and the US, we perform a new statistical test to detect cross-correlations and apply a new methodology called Multifractal Detrended Cross-Correlation Analysis (MF-DCCA), which is an efficient algorithm to analyze two spatially or temporally correlated time series. We discuss theoretically the relationship between the bivariate cross-correlation exponent and the generalized Hurst exponents for time series of respective variables. We also perform an empirical study and find that there exists a power-law cross-correlation between them, and that multifractal features are significant in all the analyzed agricultural commodity futures markets.

  16. Complications associated with the apnea test in the determination of the brain death

    Institute of Scientific and Technical Information of China (English)

    WU Xiao-liang; FANG Qiang; LI Li; QIU Yun-qing; LUO Ben-yan

    2008-01-01

    Background An apnea test is essentialin the clinical determination of brain death.This study was conducted to analyse complications associated with the apnea test in the determination of the brain death.Methods On 93 adult patients In coma in Zhejiang Province of China from January 2003 to December 2006,179 apnea tests were performed as a part of the determination of brain death.Potential risk conditions and complications were analysed during apnea tests.Results During apnea,sedous cardiac arrhythmia did not occur in all patients.Complications occurred in 37 of 179 (21%)apnea tests.Hypotension occurred in 30 patients(17%)and it was obsewed in 8/94(9%)tests with baseline value of systolic arterial blood pressure not less than 120 mmHg,and 22/85(26%)lass than 120 mmHg(P<0.05).Severe hypoxaemia occurred in 10 patients(6%)of which 3/138(2%)tests with baseline value of arterial oxygen pressure not less than 200 mmHg,and 7/41(17%)less than 200 mmHg(P<0.05).Conclusions This study demonstrated that complications occurred mostly in patients with inadequate baseline systolic arterial blood pressure and preoxygenation.Adequate precautions during the apnea tests may reduce the risk of cardiovascular and oxygenation complication.

  17. Body mass estimates of an exceptionally complete Stegosaurus (Ornithischia: Thyreophora): comparing volumetric and linear bivariate mass estimation methods.

    Science.gov (United States)

    Brassey, Charlotte A; Maidment, Susannah C R; Barrett, Paul M

    2015-03-01

    Body mass is a key biological variable, but difficult to assess from fossils. Various techniques exist for estimating body mass from skeletal parameters, but few studies have compared outputs from different methods. Here, we apply several mass estimation methods to an exceptionally complete skeleton of the dinosaur Stegosaurus. Applying a volumetric convex-hulling technique to a digital model of Stegosaurus, we estimate a mass of 1560 kg (95% prediction interval 1082-2256 kg) for this individual. By contrast, bivariate equations based on limb dimensions predict values between 2355 and 3751 kg and require implausible amounts of soft tissue and/or high body densities. When corrected for ontogenetic scaling, however, volumetric and linear equations are brought into close agreement. Our results raise concerns regarding the application of predictive equations to extinct taxa with no living analogues in terms of overall morphology and highlight the sensitivity of bivariate predictive equations to the ontogenetic status of the specimen. We emphasize the significance of rare, complete fossil skeletons in validating widely applied mass estimation equations based on incomplete skeletal material and stress the importance of accurately determining specimen age prior to further analyses.

  18. An inquisition into bivariate threshold effects in the inflation-growth correlation: Evaluating South Africa’s macroeconomic objectives

    Directory of Open Access Journals (Sweden)

    Andrew Phiri

    2013-10-01

    Full Text Available Is the SARB’s inflation target of 3-6% compatible with the 6% economic growth objective set by ASGISA? Estimations of inflation-growth bivariate Threshold Vector Autoregressive with corresponding bivariate Threshold Vector Error Correction (BTVEC-BTVAR econometric models for sub-periods coupled with the South African inflation-growth experience between 1960 and 2010; suggest on optimal inflation-growth combinations for South African data presenting a two-fold proposition. Firstly, for the performance of economic growth to improve so it coincides with the 6% target objective as defined by ASGISA, may require the sustainment of an inflation rate of below 3.08%. Secondly, given the current economic environment with inflation averages of above 3.08% and economic growth rates of below 5.58%, lower inflation rates are to be best pursued through the attainment of higher economic growth rates. Consequentially, the overall implication of the study offers support in favour of a lower, ‘close-to-zero’ inflation target as a means of ensuring improved macroeconomic performance within the economy, while simultaneously contending that it would prove beneficial for stabilization economic policies to be devised such that these low levels of inflation are attained through higher economic growth rates.

  19. Bivariate mass-size relation as a function of morphology as determined by Galaxy Zoo 2 crowdsourced visual classifications

    Science.gov (United States)

    Beck, Melanie; Scarlata, Claudia; Fortson, Lucy; Willett, Kyle; Galloway, Melanie

    2016-01-01

    It is well known that the mass-size distribution evolves as a function of cosmic time and that this evolution is different between passive and star-forming galaxy populations. However, the devil is in the details and the precise evolution is still a matter of debate since this requires careful comparison between similar galaxy populations over cosmic time while simultaneously taking into account changes in image resolution, rest-frame wavelength, and surface brightness dimming in addition to properly selecting representative morphological samples.Here we present the first step in an ambitious undertaking to calculate the bivariate mass-size distribution as a function of time and morphology. We begin with a large sample (~3 x 105) of SDSS galaxies at z ~ 0.1. Morphologies for this sample have been determined by Galaxy Zoo crowdsourced visual classifications and we split the sample not only by disk- and bulge-dominated galaxies but also in finer morphology bins such as bulge strength. Bivariate distribution functions are the only way to properly account for biases and selection effects. In particular, we quantify the mass-size distribution with a version of the parametric Maximum Likelihood estimator which has been modified to account for measurement errors as well as upper limits on galaxy sizes.

  20. Collective estimation of multiple bivariate density functions with application to angular-sampling-based protein loop modeling

    KAUST Repository

    Maadooliat, Mehdi

    2015-10-21

    This paper develops a method for simultaneous estimation of density functions for a collection of populations of protein backbone angle pairs using a data-driven, shared basis that is constructed by bivariate spline functions defined on a triangulation of the bivariate domain. The circular nature of angular data is taken into account by imposing appropriate smoothness constraints across boundaries of the triangles. Maximum penalized likelihood is used to fit the model and an alternating blockwise Newton-type algorithm is developed for computation. A simulation study shows that the collective estimation approach is statistically more efficient than estimating the densities individually. The proposed method was used to estimate neighbor-dependent distributions of protein backbone dihedral angles (i.e., Ramachandran distributions). The estimated distributions were applied to protein loop modeling, one of the most challenging open problems in protein structure prediction, by feeding them into an angular-sampling-based loop structure prediction framework. Our estimated distributions compared favorably to the Ramachandran distributions estimated by fitting a hierarchical Dirichlet process model; and in particular, our distributions showed significant improvements on the hard cases where existing methods do not work well.

  1. An assessment on the use of bivariate, multivariate and soft computing techniques for collapse susceptibility in GIS environ

    Indian Academy of Sciences (India)

    Işık Yilmaz; Marian Marschalko; Martin Bednarik

    2013-04-01

    The paper presented herein compares and discusses the use of bivariate, multivariate and soft computing techniques for collapse susceptibility modelling. Conditional probability (CP), logistic regression (LR) and artificial neural networks (ANN) models representing the bivariate, multivariate and soft computing techniques were used in GIS based collapse susceptibility mapping in an area from Sivas basin (Turkey). Collapse-related factors, directly or indirectly related to the causes of collapse occurrence, such as distance from faults, slope angle and aspect, topographical elevation, distance from drainage, topographic wetness index (TWI), stream power index (SPI), Normalized Difference Vegetation Index (NDVI) by means of vegetation cover, distance from roads and settlements were used in the collapse susceptibility analyses. In the last stage of the analyses, collapse susceptibility maps were produced from the models, and they were then compared by means of their validations. However, Area Under Curve (AUC) values obtained from all three models showed that the map obtained from soft computing (ANN) model looks like more accurate than the other models, accuracies of all three models can be evaluated relatively similar. The results also showed that the conditional probability is an essential method in preparation of collapse susceptibility map and highly compatible with GIS operating features.

  2. Classification of Knee Joint Vibration Signals Using Bivariate Feature Distribution Estimation and Maximal Posterior Probability Decision Criterion

    Directory of Open Access Journals (Sweden)

    Fang Zheng

    2013-04-01

    Full Text Available Analysis of knee joint vibration or vibroarthrographic (VAG signals using signal processing and machine learning algorithms possesses high potential for the noninvasive detection of articular cartilage degeneration, which may reduce unnecessary exploratory surgery. Feature representation of knee joint VAG signals helps characterize the pathological condition of degenerative articular cartilages in the knee. This paper used the kernel-based probability density estimation method to model the distributions of the VAG signals recorded from healthy subjects and patients with knee joint disorders. The estimated densities of the VAG signals showed explicit distributions of the normal and abnormal signal groups, along with the corresponding contours in the bivariate feature space. The signal classifications were performed by using the Fisher’s linear discriminant analysis, support vector machine with polynomial kernels, and the maximal posterior probability decision criterion. The maximal posterior probability decision criterion was able to provide the total classification accuracy of 86.67% and the area (Az of 0.9096 under the receiver operating characteristics curve, which were superior to the results obtained by either the Fisher’s linear discriminant analysis (accuracy: 81.33%, Az: 0.8564 or the support vector machine with polynomial kernels (accuracy: 81.33%, Az: 0.8533. Such results demonstrated the merits of the bivariate feature distribution estimation and the superiority of the maximal posterior probability decision criterion for analysis of knee joint VAG signals.

  3. Operator identities involving the bivariate Rogers-Szegö polynomials and their applications to the multiple q-series identities

    Science.gov (United States)

    Zhang, Zhizheng; Wang, Tianze

    2008-07-01

    In this paper, we first give several operator identities involving the bivariate Rogers-Szegö polynomials. By applying the technique of parameter augmentation to the multiple q-binomial theorems given by Milne [S.C. Milne, Balanced summation theorems for U(n) basic hypergeometric series, AdvE Math. 131 (1997) 93-187], we obtain several new multiple q-series identities involving the bivariate Rogers-Szegö polynomials. These include multiple extensions of Mehler's formula and Rogers's formula. Our U(n+1) generalizations are quite natural as they are also a direct and immediate consequence of their (often classical) known one-variable cases and Milne's fundamental theorem for An or U(n+1) basic hypergeometric series in Theorem 1E49 of [S.C. Milne, An elementary proof of the Macdonald identities for , Adv. Math. 57 (1985) 34-70], as rewritten in Lemma 7.3 on p. 163 of [S.C. Milne, Balanced summation theorems for U(n) basic hypergeometric series, Adv. Math. 131 (1997) 93-187] or Corollary 4.4 on pp. 768-769 of [S.C. Milne, M. Schlosser, A new An extension of Ramanujan's summation with applications to multilateral An series, Rocky Mountain J. Math. 32 (2002) 759-792].

  4. Optical Coherence Tomography Noise Reduction Using Anisotropic Local Bivariate Gaussian Mixture Prior in 3D Complex Wavelet Domain

    Directory of Open Access Journals (Sweden)

    Hossein Rabbani

    2013-01-01

    Full Text Available In this paper, MMSE estimator is employed for noise-free 3D OCT data recovery in 3D complex wavelet domain. Since the proposed distribution for noise-free data plays a key role in the performance of MMSE estimator, a priori distribution for the pdf of noise-free 3D complex wavelet coefficients is proposed which is able to model the main statistical properties of wavelets. We model the coefficients with a mixture of two bivariate Gaussian pdfs with local parameters which are able to capture the heavy-tailed property and inter- and intrascale dependencies of coefficients. In addition, based on the special structure of OCT images, we use an anisotropic windowing procedure for local parameters estimation that results in visual quality improvement. On this base, several OCT despeckling algorithms are obtained based on using Gaussian/two-sided Rayleigh noise distribution and homomorphic/nonhomomorphic model. In order to evaluate the performance of the proposed algorithm, we use 156 selected ROIs from 650 × 512 × 128 OCT dataset in the presence of wet AMD pathology. Our simulations show that the best MMSE estimator using local bivariate mixture prior is for the nonhomomorphic model in the presence of Gaussian noise which results in an improvement of 7.8 ± 1.7 in CNR.

  5. Application of multivariate statistics to vestibular testing: discriminating between Meniere's disease and migraine associated dizziness

    Science.gov (United States)

    Dimitri, P. S.; Wall, C. 3rd; Oas, J. G.; Rauch, S. D.

    2001-01-01

    Meniere's disease (MD) and migraine associated dizziness (MAD) are two disorders that can have similar symptomatologies, but differ vastly in treatment. Vestibular testing is sometimes used to help differentiate between these disorders, but the inefficiency of a human interpreter analyzing a multitude of variables independently decreases its utility. Our hypothesis was that we could objectively discriminate between patients with MD and those with MAD using select variables from the vestibular test battery. Sinusoidal harmonic acceleration test variables were reduced to three vestibulo-ocular reflex physiologic parameters: gain, time constant, and asymmetry. A combination of these parameters plus a measurement of reduced vestibular response from caloric testing allowed us to achieve a joint classification rate of 91%, independent quadratic classification algorithm. Data from posturography were not useful for this type of differentiation. Overall, our classification function can be used as an unbiased assistant to discriminate between MD and MAD and gave us insight into the pathophysiologic differences between the two disorders.

  6. Item and associative memory in amnestic mild cognitive impairment: performance on standardized memory tests.

    Science.gov (United States)

    Troyer, Angela K; Murphy, Kelly J; Anderson, Nicole D; Hayman-Abello, Brent A; Craik, Fergus I M; Moscovitch, Morris

    2008-01-01

    The earliest neuroanatomical changes in amnestic mild cognitive impairment (aMCI) involve the hippocampus and entorhinal cortex, structures implicated in the integration and learning of associative information. The authors hypothesized that individuals with aMCI would have impairments in associative memory above and beyond the known impairments in item memory. A group of 29 individuals with aMCI and 30 matched control participants were administered standardized tests of object-location recall and symbol-symbol recall, from which both item and associative recall scores were derived. As expected, item recall was impaired in the aMCI group relative to controls. Associative recall in the aMCI group was even more impaired than was item recall. The best group discriminators were measures of associative recall, with which the sensitivity and specificity for detecting aMCI were 76% and 90% for symbol-symbol recall and were 86% and 97% for object-location recall. Associative recall may be particularly sensitive to early cognitive change in aMCI, because this ability relies heavily on the medial temporal lobe structures that are affected earliest in aMCI. Incorporating measures of associative recall into clinical evaluations of individuals with memory change may be useful for detecting aMCI.

  7. Is red the colour of danger? Testing an implicit red-danger association.

    Science.gov (United States)

    Pravossoudovitch, Karyn; Cury, Francois; Young, Steve G; Elliot, Andrew J

    2014-01-01

    Research using participant's self-reports has documented a link between red and danger. In this research, we used two different variants of a Stroop word evaluation task to test for the possibility of an implicit red-danger association using carefully controlled colour stimuli (equated on lightness and chroma). Experiment 1, using words as stimuli, yielded strong evidence of a link between red and danger, and weaker evidence of a green-safety association. Experiment 2, using symbols as stimuli, again yielded strong evidence of a link between red and danger; no green effects were observed. The findings were discussed in terms of the power and promise of red in signal communication.

  8. Family-based association test method: age of onset traits and covariates.

    Science.gov (United States)

    Horvath, S; Wei, E; Xu, X; Palmer, L J; Baur, M

    2001-01-01

    We apply different family-based association test (FBAT) statistics for age of onset traits to the Genetics Analysis Workshop 12, problem 2 data. To evaluate different FBAT statistics we used the software package FBAT, which allows one to evaluate any test statistic that can be expressed as the sum of products between an arbitrary function of an offspring's genotype with an arbitrary function of the offspring's phenotype even if there are missing parental information. For single nucleotide polymorphisms (SNPs) in gene 1, our age-of-onset FBAT test based on the exponential model is significantly more powerful than the test by Mokliatchouk et al. [Hum Hered 51:46-53, 2000], which is based on the Cox model. We suggest incorporating covariates into FBAT statistics by replacing the trait values by their regression residuals. For the age of onset trait statistics we find that deviance residuals have much more power than "plain" martingale residuals. We discuss why for SNPs in gene 1, the usual affectation status trait, which underlies the transmission disequilibrium test (TDT), has higher power than the age-of-onset trait. We find only weak evidence (p = 0.0002) that marker D06G032 is associated with the affectation status.

  9. VIGOR TESTS ASSOCIATION AS AN ALTERNATIVE FOR PRECISE AND EFFICIENT ASSESSMENT OF MAIZE SEED QUALITY

    Directory of Open Access Journals (Sweden)

    MARCOS ALTOMANI NEVES DIAS

    2015-01-01

    Full Text Available This study aimed to associate two concepts of seed vigor testing, the aging and seedling growth using image analysis, providing a feasible and time-saving way to evaluate maize seed vigor in large scale. For this purpose, five seed lots with different vigor levels from two single hybrids were used. The seeds were characterized by moisture content, germination, seedling emergence, seedling emergence speed index, accelerated aging and cold tests. The treatments were composed by varying the accelerated aging periods (0, 24, 48, 72 and 96h and seedling growth periods (48 and 72h, before submitting the seedlings to image analysis for seedling root length measurement. Considering the results obtained, the adaptation of accelerated aging test by reducing the aging duration from 96h to 48h, and the replacement of the germination test by seedling root length measurement using image analysis could be considered a potential tool for maize seed vigor assessment. The treatments composed of 48h of seed aging followed by seedlings root length measurements using image analysis provided reliable data, compared to traditional vigor tests and it could be considered an efficient and timesaving approach, associating two different concepts of seed vigor analysis.

  10. Examining Bivariate Item-Criterion Associations: A Method of Exploring Personality Correlates of Job-Related Behavior

    Science.gov (United States)

    1988-07-05

    the sample size, the criterion substantially exceeded the magnitude required for statistical significance as estimated in simulation studies ( Gorsuch ...persons and situations. Psychological Bulletin, 82, 278-288. Gorsuch , R.L. (1974). Factor Analysis. Philadelphia, PA: W. B. Saunders Company. Gough, H.G

  11. Identifying genetic marker sets associated with phenotypes via an efficient adaptive score test

    KAUST Repository

    Cai, T.

    2012-06-25

    In recent years, genome-wide association studies (GWAS) and gene-expression profiling have generated a large number of valuable datasets for assessing how genetic variations are related to disease outcomes. With such datasets, it is often of interest to assess the overall effect of a set of genetic markers, assembled based on biological knowledge. Genetic marker-set analyses have been advocated as more reliable and powerful approaches compared with the traditional marginal approaches (Curtis and others, 2005. Pathways to the analysis of microarray data. TRENDS in Biotechnology 23, 429-435; Efroni and others, 2007. Identification of key processes underlying cancer phenotypes using biologic pathway analysis. PLoS One 2, 425). Procedures for testing the overall effect of a marker-set have been actively studied in recent years. For example, score tests derived under an Empirical Bayes (EB) framework (Liu and others, 2007. Semiparametric regression of multidimensional genetic pathway data: least-squares kernel machines and linear mixed models. Biometrics 63, 1079-1088; Liu and others, 2008. Estimation and testing for the effect of a genetic pathway on a disease outcome using logistic kernel machine regression via logistic mixed models. BMC bioinformatics 9, 292-2; Wu and others, 2010. Powerful SNP-set analysis for case-control genome-wide association studies. American Journal of Human Genetics 86, 929) have been proposed as powerful alternatives to the standard Rao score test (Rao, 1948. Large sample tests of statistical hypotheses concerning several parameters with applications to problems of estimation. Mathematical Proceedings of the Cambridge Philosophical Society, 44, 50-57). The advantages of these EB-based tests are most apparent when the markers are correlated, due to the reduction in the degrees of freedom. In this paper, we propose an adaptive score test which up- or down-weights the contributions from each member of the marker-set based on the Z-scores of

  12. Position Weight Matrix, Gibbs Sampler, and the Associated Significance Tests in Motif Characterization and Prediction

    Directory of Open Access Journals (Sweden)

    Xuhua Xia

    2012-01-01

    Full Text Available Position weight matrix (PWM is not only one of the most widely used bioinformatic methods, but also a key component in more advanced computational algorithms (e.g., Gibbs sampler for characterizing and discovering motifs in nucleotide or amino acid sequences. However, few generally applicable statistical tests are available for evaluating the significance of site patterns, PWM, and PWM scores (PWMS of putative motifs. Statistical significance tests of the PWM output, that is, site-specific frequencies, PWM itself, and PWMS, are in disparate sources and have never been collected in a single paper, with the consequence that many implementations of PWM do not include any significance test. Here I review PWM-based methods used in motif characterization and prediction (including a detailed illustration of the Gibbs sampler for de novo motif discovery, present statistical and probabilistic rationales behind statistical significance tests relevant to PWM, and illustrate their application with real data. The multiple comparison problem associated with the test of site-specific frequencies is best handled by false discovery rate methods. The test of PWM, due to the use of pseudocounts, is best done by resampling methods. The test of individual PWMS for each sequence segment should be based on the extreme value distribution.

  13. Is Psychological Testing Useful in Forensic Contexts that are Associated with Underreporting?

    Directory of Open Access Journals (Sweden)

    Robert A Semel

    2016-06-01

    Full Text Available The validity of self-report psychological test results in forensic contexts may be compromised as a result of examinee response style bias to over report or underreport psychological problems. This paper briefly discusses two forensic contexts associated with tendencies of examinees to underreport problems, i.e., child custody evaluations and juvenile delinquency evaluations for disposition. Despite the finding that most examinees in both of these populations obtain within normal limits scores on clinical scales, it is suggested that testing may be helpful in identifying potential problems in some segment of each of these forensic populations. This opinion is supported by findings in empirical studies.

  14. Brief implicit association test: Validity and utility in prediction of voting behavior

    Directory of Open Access Journals (Sweden)

    Pavlović Maša D.

    2013-01-01

    Full Text Available We employed the Brief Implicit Association Test (a recently developed short version of IAT to measure implicit political attitudes toward four political parties running for Serbian parliament. To test its criterion validity, we measured voting intention and actual voting behavior. In addition, we introduced political involvement as a potential moderator of the BIAT’s predictive and incremental validity. The BIAT demonstrated good internal and predictive validity, but lacked incremental validity over self-report measures. Predictive power of the BIAT was moderated by political involvement - the BIAT scores were stronger predictors of voting intention and behavior among voters highly involved in politics. [Projekat Ministarstva nauke Republike Srbije, br. 179018

  15. Determining the cognitive structures of science teacher candidates on “evolution” through word association test

    Directory of Open Access Journals (Sweden)

    Arzu ÖNEL

    2016-04-01

    Full Text Available This study tried to determine the conceptual comprehension of science teacher candidates on evolution. As part of this target, the Word Association Test was applied. This study was conducted with the participation of 146 teacher candidates studying in the Department of Science Education. Of the 146 teacher candidates, 89 mostly wrote the words; “evolution” (f=43, “Darwin” (f=36, and “ape” (f=10 as primary concepts in the word association test. This result illustrated that when the word “evolution” was pronounced, 61% of teacher candidates firstly remembered these three words as primary concepts. This study has demonstrated once more that there are misunderstandings and missing data on the evolutionary theory despite the past 156 years from the emergence of this theory.

  16. Evaluation of the Canadian Rheumatology Association Choosing Wisely recommendation concerning anti-nuclear antibody (ANA) testing.

    Science.gov (United States)

    Ferrari, Robert

    2015-09-01

    The objective of this study was to evaluate the Canadian Rheumatology Association Choosing Wisely recommendation concerning anti-nuclear antibody (ANA) testing. Patients with joint pain/stiffness/swelling were assessed to determine if ANA testing was indicated. An a priori threshold was set before ANA testing would be considered. Those who did not have ANA testing ordered were followed for 1 year to determine if any of them went on to have a diagnosis of systemic lupus erythematosus (SLE) or other connective tissue disease. A parallel study was conducted with a similar a priori threshold for the use of rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibody testing in the diagnosis of rheumatoid arthritis (RA), and again, patients were followed for 1 year. A total of 866 subjects were examined, 509 females (58.8 %) and 357 males (41.2 %). The mean age of the group was 47.5 ± 16.8 years. The mean duration of symptoms was 12.0 ± 5.6 weeks. Of the 866 subjects, 68 met an a priori threshold for ordering ANA, RF, and anti-CCP testing. Of these 68, there was a newly diagnosed case of SLE, 4 newly diagnosed cases of RA, and 3 cases of polymyalgia rheumatica. The remaining 798 subjects were followed for approximately 1 year and none developed evidence of SLE, RA, or other connective tissue disease. In the evaluation of non-specific musculoskeletal symptoms, setting an a priori threshold for ordering serology in keeping with the spirit of the Canadian Rheumatology Association Choosing Wisely recommendation for antibody testing results in a very low risk of missing a case of systemic lupus erythematosus or rheumatoid arthritis.

  17. Baseline and Verification Tests of the Electric Vehicle Associates’ Current Fare Station Wagon.

    Science.gov (United States)

    1983-01-01

    the EVA Current Fare Wagon. The EVA Current Fare Wagon is a 1980 Ford Fairmont station wagon which has been converted to an electric vehicle . The...standard Ford Fairmont station wagon which has been converted to an electric vehicle (Figures 1 anil 2). It is powered I% 22 6-V lead-acid batteries2...D-R132 549 BASELINE AND VERIFICATION TESTS OF THE ELECTRIC VEHICLE 112 ASSOCIATES’ CURRE..(U) ARMY MOBILITY EQUIPMENT RESEARCH AIND DEVELOPMENT

  18. Testing SNPs and sets of SNPs for importance in association studies

    OpenAIRE

    Schwender, Holger; Ruczinski, Ingo; Ickstadt, Katja

    2010-01-01

    A major goal of genetic association studies concerned with single nucleotide polymorphisms (SNPs) is the detection of SNPs exhibiting an impact on the risk of developing a disease. Typically, this problem is approached by testing each of the SNPs individually. This, however, can lead to an inaccurate measurement of the influence of the SNPs on the disease risk, in particular, if SNPs only show an effect when interacting with other SNPs, as the multivariate structure of the data is ignored. In...

  19. Poisson Approximation-Based Score Test for Detecting Association of Rare Variants.

    Science.gov (United States)

    Fang, Hongyan; Zhang, Hong; Yang, Yaning

    2016-07-01

    Genome-wide association study (GWAS) has achieved great success in identifying genetic variants, but the nature of GWAS has determined its inherent limitations. Under the common disease rare variants (CDRV) hypothesis, the traditional association analysis methods commonly used in GWAS for common variants do not have enough power for detecting rare variants with a limited sample size. As a solution to this problem, pooling rare variants by their functions provides an efficient way for identifying susceptible genes. Rare variant typically have low frequencies of minor alleles, and the distribution of the total number of minor alleles of the rare variants can be approximated by a Poisson distribution. Based on this fact, we propose a new test method, the Poisson Approximation-based Score Test (PAST), for association analysis of rare variants. Two testing methods, namely, ePAST and mPAST, are proposed based on different strategies of pooling rare variants. Simulation results and application to the CRESCENDO cohort data show that our methods are more powerful than the existing methods.

  20. Test Anxiety Associated with High-Stakes Testing among Elementary School Children: Prevalence, Predictors, and Relationship to Student Performance

    Science.gov (United States)

    Segool, Natasha Katherine

    2009-01-01

    The current study explored differences in test anxiety on high-stakes standardized achievement testing and classroom testing among elementary school children. This is the first study to directly examine differences in student test anxiety across two testing conditions with different stakes among young children. Three hundred and thirty-five…

  1. Problems associated with the apnea test in the diagnosis of brain death

    Directory of Open Access Journals (Sweden)

    Saposnik Gustavo

    2004-07-01

    Full Text Available Background: Brain death is the absence of all cortical functions, including the brainstem. The apnea test (AT is a necessary requisite to complete this diagnosis. Anecdotal reports describing hypotension and acidosis due to apnea test have been reported. However, there are few studies that evaluate complications or difficulties related to this procedure. Objective: To analyze medical problems associated with the apnea test. Methods and Patients: We analyzed clinical features, potential risk conditions, and problems in 129 brain dead patients during the apnea test. The diagnosis of brain death was made according to the American Academy of Neurology recommendations. Results: Clinical problems during the apnea test were detected in more than two thirds of patients, including: arterial hypotension (12%, acidosis (68%, and hypoxemia (23%. Four patients developed major complications, including: pneumothorax, cardiac arrest, bradycardia, atrial fibrillation and myocardial infarction. Conclusion: The apnea test is not an innocuous procedure. Complications during the AT are more common than reported and limit organ procurement for transplantation. Guidelines for performing the AT should be followed in order to avoid clinical complications.

  2. An Adaptive Association Test for Multiple Phenotypes with GWAS Summary Statistics.

    Science.gov (United States)

    Kim, Junghi; Bai, Yun; Pan, Wei

    2015-12-01

    We study the problem of testing for single marker-multiple phenotype associations based on genome-wide association study (GWAS) summary statistics without access to individual-level genotype and phenotype data. For most published GWASs, because obtaining summary data is substantially easier than accessing individual-level phenotype and genotype data, while often multiple correlated traits have been collected, the problem studied here has become increasingly important. We propose a powerful adaptive test and compare its performance with some existing tests. We illustrate its applications to analyses of a meta-analyzed GWAS dataset with three blood lipid traits and another with sex-stratified anthropometric traits, and further demonstrate its potential power gain over some existing methods through realistic simulation studies. We start from the situation with only one set of (possibly meta-analyzed) genome-wide summary statistics, then extend the method to meta-analysis of multiple sets of genome-wide summary statistics, each from one GWAS. We expect the proposed test to be useful in practice as more powerful than or complementary to existing methods.

  3. Factors associated with HIV testing among male motorbike taxi drivers in urban Vietnam.

    Science.gov (United States)

    Huy, Nguyen Van; Khuyen, Le Thi; Ha, Pham Nguyen

    2015-01-01

    Using the Attitude-Skills-Knowledge (ASK) model, this study examined the prevalence of, and factors associated with, human immunodeficiency virus (HIV) testing among male motorbike taxi drivers (MMTDs). In a cross-sectional design, using quantitative approaches, 291 MMTDs were recruited from 135 sites across 13 districts in Hanoi, Vietnam, for a face-to-face interview. Applying the ASK model modified as a central theory, logistic regression was used to identify determinants of HIV testing. Although many MMTDs engaged in multiple risk behaviours for HIV, only 20.6% had been tested for HIV during the past 12 months. The tested model included one factor of the ASK model, HIV prevention knowledge (adjusted odds ratio [AOR] = 4.76; 95% confidence interval [CI] = 2.12-10.7) and five additional factors: being married (AOR = 3.13; 95% CI = 1.25-4.78), preferring sex with men or with both men and women (AOR = 8.72; 95% CI = 1.48-51.5), having lower number of lifetime sex partners (AOR = 0.66; 95% CI = 0.49-0.88), higher number of past year sex partners (AOR = 2.97: 95% CI = 1.21-7.31) and discussing condom use when having sex with partners (AOR = 0.08; 95% CI = 0.01-7.31). This modified ASK model provided better fit than the ASK model, as it explained more variance in HIV testing (47 vs. 29.8%). Recognising factors associated with HIV testing among MMTDs enables us to create suitable public health intervention strategies.

  4. Distance to testing sites and its association with timing of HIV diagnosis.

    Science.gov (United States)

    Cope, Anna B; Powers, Kimberly A; Serre, Marc L; Escamilla, Veronica; Emch, Michael E; Leone, Peter A; Mobley, Victoria L; Miller, William C

    2016-11-01

    Early HIV diagnosis enables prompt treatment initiation, thereby contributing to decreased morbidity, mortality, and transmission. We aimed to describe the association between distance from residence to testing sites and HIV disease stage at diagnosis. Using HIV surveillance data, we identified all new HIV diagnoses made at publicly funded testing sites in central North Carolina during 2005-2013. Early-stage HIV was defined as acute HIV (antibody-negative test with a positive HIV RNA) or recent HIV (normalized optical density HIV. Street distance between residence at diagnosis and (1) the closest testing site and (2) the diagnosis site was dichotomized at 5 miles. We fit log-binomial models using generalized estimating equations to estimate prevalence ratios (PR) and robust 95% confidence intervals (CI) for post-early-stage diagnoses by distance. Models were adjusted for race/ethnicity and testing period. Most of the 3028 new diagnoses were black (N = 2144; 70.8%), men who have sex with men (N = 1685; 55.7%), and post-early-stage HIV diagnoses (N = 2010; 66.4%). Overall, 1145 (37.8%) cases traveled diagnosis. Among cases traveling ≥5 miles for a diagnosis, 1273 (67.6%) lived HIV (adjusted PR, 95% CI: 0.98, 0.92-1.04), but traveling ≥5 miles for a diagnosis was associated with higher post-early HIV prevalence (1.07, 1.02-1.13). Most of the elevated prevalence observed in cases traveling ≥5 miles for a diagnosis occurred among those living HIV diagnosis were apparent among persons living near a site, but choosing to travel longer distances to test. Understanding reasons for increased travel distances could improve accessibility and acceptability of HIV services and increase early diagnosis rates.

  5. Identifying temporal and causal contributions of neural processes underlying the Implicit Association Test (IAT

    Directory of Open Access Journals (Sweden)

    Chad Edward Forbes

    2012-11-01

    Full Text Available The Implicit Association Test (IAT is a popular behavioral measure that assesses the associative strength between outgroup members and stereotypical and counterstereotypical traits. Less is known, however, about the degree to which the IAT reflects automatic processing. Two studies examined automatic processing contributions to a gender-IAT using a data driven, social neuroscience approach. Performance on congruent (e.g., categorizing male names with synonyms of strength and incongruent (e.g., categorizing female names with synonyms of strength IAT blocks were separately analyzed using EEG (event-related potentials, or ERPs, and coherence; Study 1 and lesion (Study 2 methodologies. Compared to incongruent blocks, performance on congruent IAT blocks was associated with more positive ERPs that manifested in frontal and occipital regions at automatic processing speeds, occipital regions at more controlled processing speeds and was compromised by volume loss in the anterior temporal lobe, insula and medial PFC. Performance on incongruent blocks was associated with volume loss in supplementary motor areas, cingulate gyrus and a region in medial PFC similar to that found for congruent blocks. Greater coherence was found between frontal and occipital regions to the extent individuals exhibited more bias. This suggests there are separable neural contributions to congruent and incongruent blocks of the IAT but there is also a surprising amount of overlap. Given the temporal and regional neural distinctions, these results provide converging evidence that stereotypic associative strength assessed by the IAT indexes automatic processing to a degree.

  6. Social and genetic structure of paper wasp cofoundress associations: tests of reproductive skew models.

    Science.gov (United States)

    Field, J; Solís, C R; Queller, D C; Strassmann, J E

    1998-06-01

    Recent models postulate that the members of a social group assess their ecological and social environments and agree a "social contract" of reproductive partitioning (skew). We tested social contracts theory by using DNA microsatellites to measure skew in 24 cofoundress associations of paper wasps, Polistes bellicosus. In contrast to theoretical predictions, there was little variation in cofoundress relatedness, and relatedness either did not predict skew or was negatively correlated with it; the dominant/subordinate size ratio, assumed to reflect relative fighting ability, did not predict skew; and high skew was associated with decreased aggression by the rank 2 subordinate toward the dominant. High skew was associated with increased group size. A difficulty with measuring skew in real systems is the frequent changes in group composition that commonly occur in social animals. In P. bellicosus, 61% of egg layers and an unknown number of non-egg layers were absent by the time nests were collected. The social contracts models provide an attractive general framework linking genetics, ecology, and behavior, but there have been few direct tests of their predictions. We question assumptions underlying the models and suggest directions for future research.

  7. Association Between Allergic Diseases and Food Allergens Based on Skin Prick Test in Bushehr Province

    Directory of Open Access Journals (Sweden)

    Saman Keshvari

    2017-04-01

    Full Text Available Background: The Frequency of allergic diseases is growing in recent years. Identification of frequency of food allergens in different areas play an important role in diagnosis and treatment of these diseases. The aim of this study was to determine frequency and association of common food allergens in patients with allergic diseases based on Skin Prick Test in Bushehr province. Material and Methods: In this descriptive cross-sectional study, 1100 patients were enrolled with allergic diseases which had a sensitivity to at least one allergen.  This test was carried out with 21 common food allergens extract. Results: In all patients, association between the severity of the reaction prick allergy test and severity of allergic diseases with shrimp, cow's Milk and peanuts were (P= 0.01, (P= 0.02 and (P=0.04 respectively. In this study, the frequency of allergic rhinitis, asthma, chronic and acute urticaris and atopic eczema were 54.2%, 23%, 12.4%, 4.1% and 12%, respectively. While the the most common food allergens were peanuts (46.6%, egg yolk (43.1% and shrimp (42% respectively. Conclusion: This study indicated that food allergens such as shrimp, cow's Milk and peanuts have a greater role in severity of allergic diseases and this food allergens showed the highest frequency in patients.

  8. Sites of dermatitis in a patch test population: hand dermatitis is associated with polysensitization

    DEFF Research Database (Denmark)

    Carlsen, B C; Andersen, K E; Menné, T

    2009-01-01

    . METHODS: A matched case-control study was carried out including 394 polysensitized and 726 single/double-sensitized patients who responded to a postal questionnaire. All subjects were recruited from a hospital patch test population. RESULTS: The hands were the most frequent and the anogenital region...... was the least frequent skin area affected with dermatitis. Dermatitis on the hands/wrists [odds ratio (OR) 1.58], in the armpits (OR 1.56) and on the back (OR 1.91) was positively associated with polysensitization. The hands were the only skin area with dermatitis which maintained the association...... compared with single/double-sensitized patients. CONCLUSIONS: Special awareness in patients with hand dermatitis seems justified either to prevent development of multiple contact allergies or to document polysensitization as an aetiological factor....

  9. Clinical relevance is associated with allergen-specific wheal size in skin prick testing

    DEFF Research Database (Denmark)

    Haahtela, T.; Burbach, G. J.; Bachert, C.;

    2014-01-01

    BackgroundWithin a large prospective study, the Global Asthma and Allergy European Network (GA(2)LEN) has collected skin prick test (SPT) data throughout Europe to make recommendations for SPT in clinical settings. ObjectiveTo improve clinical interpretation of SPT results for inhalant allergens...... by providing quantitative decision points. MethodsThe GA(2)LEN SPT study with 3068 valid data sets was used to investigate the relationship between SPT results and patient-reported clinical relevance for each of the 18 inhalant allergens as well as SPT wheal size and physician-diagnosed allergy (rhinitis......) to 87-89% (grass, mites) of the positive SPT reactions (wheal size3mm) were associated with patient-reported clinical symptoms when exposed to the respective allergen. The risk of allergic symptoms increased significantly with larger wheal sizes for 17 of the 18 allergens tested. Children with positive...

  10. Case of cytomegalovirus-associated direct anti-globulin test-negative autoimmune hemolytic anemia.

    Science.gov (United States)

    Kaneko, Saeko; Sato, Masanori; Sasaki, Goro; Eguchi, Hiroyuki; Oishi, Tsutomu; Kamesaki, Toyomi; Kawaguchi, Hiroyuki

    2013-12-01

    A 1-year-old boy developed autoimmune hemolytic anemia after a negative direct anti-globulin test. The concentration of erythrocyte membrane-associated immunoglobulin G, determined using an immunoradiometric assay, correlated with disease activity. He was positive for cytomegalovirus (CMV) both serologically and by quantitative real-time polymerase chain reaction, indicating that his autoimmune hemolytic anemia was directly caused by CMV infection. Since anti-CMV immunoglobulin G was not absorbed by the patient's erythrocytes, cross-reaction between erythrocyte antigens and CMV was not likely a causative factor for hemolysis.

  11. Performance of juvenile baboons on neuropsychological tests assessing associative learning, motivation and attention.

    Science.gov (United States)

    Zürcher, Nicole R; Rodriguez, Jesse S; Jenkins, Sue L; Keenan, Kate; Bartlett, Thad Q; McDonald, Thomas J; Nathanielsz, Peter W; Nijland, Mark J

    2010-05-15

    The CANTAB (Cambridge Neuropsychological Test Automated Battery), a system developed for human neuropsychological testing, has previously been used to assess cognitive function in two species of nonhuman primates, common marmoset monkeys and rhesus macaques. We describe the application of the system to the juvenile baboon, a nonhuman primate species offering specific investigative advantages. Juvenile baboons were trained and tested on a progressive ratio task to assess motivation, simple discrimination and simple reversal tasks to assess associative learning, and intra- and extra-dimensional set-shifting tasks to assess selective attention and attentional set-shifting, respectively. Study subjects were 8 juvenile baboons (Papio sp.), 4 females and 4 males aged 3.0+/-0.1 (mean+SEM) years and weight 8.2+/-0.4 kg. All baboons were easily trained, readily learned the neuropsychological tests and exhibited a stable performance. Applying a method such as the CANTAB has significant implications for expanding on the translational utility of the baboon in studies of neurodevelopment.

  12. Factors associated with late diagnosis of HIV infection and missed opportunities for earlier testing.

    Science.gov (United States)

    Gullón, Alejandra; Verdejo, José; de Miguel, Rosa; Gómez, Ana; Sanz, Jesús

    2016-10-01

    Late diagnosis (LD) of human immunodeficiency virus (HIV) infection continues to be a significant problem that increases disease burden both for patients and for the public health system. Guidelines have been updated in order to facilitate earlier HIV diagnosis, introducing "indicator condition-guided HIV testing". In this study, we analysed the frequency of LD and associated risk factors. We retrospectively identified those cases that could be considered missed opportunities for an earlier diagnosis. All patients newly diagnosed with HIV infection who attended Hospital La Princesa, Madrid (Spain) between 2007 and 2014 were analysed. We collected epidemiological, clinical and immunological data. We also reviewed electronic medical records from the year before the HIV diagnosis to search for medical consultations due to clinical indicators. HIV infection was diagnosed in 354 patients. The median CD4 count at presentation was 352 cells/mm(3). Overall, 158 patients (50%) met the definition of LD, and 97 (30.7%) the diagnosis of advanced disease. LD was associated with older age and was more frequent amongst immigrants. Heterosexual relations and injection drug use were more likely to be the reasons for LD than relations between men who have sex with men. During the year preceding the diagnosis, 46.6% of the patients had sought medical advice owing to the presence of clinical indicators that should have led to HIV testing. Of those, 24 cases (14.5%) were classified as missed opportunities for earlier HIV diagnosis because testing was not performed. According to these results, all health workers should pursue early HIV diagnosis through the proper implementation of HIV testing guidelines. Such an approach would prove directly beneficial to the patient and indirectly beneficial to the general population through the reduction in the risk of transmission.

  13. Statistical distributions of test statistics used for quantitative trait association mapping in structured populations

    Directory of Open Access Journals (Sweden)

    Teyssèdre Simon

    2012-11-01

    Full Text Available Abstract Background Spurious associations between single nucleotide polymorphisms and phenotypes are a major issue in genome-wide association studies and have led to underestimation of type 1 error rate and overestimation of the number of quantitative trait loci found. Many authors have investigated the influence of population structure on the robustness of methods by simulation. This paper is aimed at developing further the algebraic formalization of power and type 1 error rate for some of the classical statistical methods used: simple regression, two approximate methods of mixed models involving the effect of a single nucleotide polymorphism (SNP and a random polygenic effect (GRAMMAR and FASTA and the transmission/disequilibrium test for quantitative traits and nuclear families. Analytical formulae were derived using matrix algebra for the first and second moments of the statistical tests, assuming a true mixed model with a polygenic effect and SNP effects. Results The expectation and variance of the test statistics and their marginal expectations and variances according to the distribution of genotypes and estimators of variance components are given as a function of the relationship matrix and of the heritability of the polygenic effect. These formulae were used to compute type 1 error rate and power for any kind of relationship matrix between phenotyped and genotyped individuals for any level of heritability. For the regression method, type 1 error rate increased with the variability of relationships and with heritability, but decreased with the GRAMMAR method and was not affected with the FASTA and quantitative transmission/disequilibrium test methods. Conclusions The formulae can be easily used to provide the correct threshold of type 1 error rate and to calculate the power when designing experiments or data collection protocols. The results concerning the efficacy of each method agree with simulation results in the literature but were

  14. Association Between Aeroallergens and Allergic Diseases Based on Skin Prick Test in Bushehr Province

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    Ali Moradi

    2017-01-01

    Full Text Available Background: The prevalence of allergic diseases is growing in the world and Iran. Allergens play an important role in creating these diseases. Since inhalation allergens are an important part of these allergens the aim of this study was to assess the prevalence of aeroallergens and their association with allergic diseases based on skin prick test (SPT. Material and Methods: In this study, the frequency of these allergens were examined by using 22 aeroallergens and based on Skin Prick Test in 1100 patients with allergic diseases who referred to Shohadaye- Khalije- Fars university hospital. Results: The reaction severity of SPT and the severity of disease associated with inhaled allergens with Russian thistle (21.1%, P꞊0.001, Chenopodium album pollen (14%, P꞊0.001 and Dermatophagoid Pteronyssinus (9%, P꞊0.001 respectively. Also, in these patients, the frequency of inhalation allergens were House Dust Mite (HDM (69%, feather (60.8%, Russian this tle (59.9% pollen and Alternaria mold (59.6% respectively. Conclusion: This study indicated that outdoors inhaled allergens  such as Russian thistle and Chenopodium album pollen have the most allergenicity in patients with allergic and asthma in Bushehr province, Meanwhile, the prevalence of indoor aeroallergens such as HDM, feather and mold were high in these patients.

  15. Water Associated Zero Maze: A novel rat test for long term traumatic re-experiencing

    Directory of Open Access Journals (Sweden)

    Gilad eRitov

    2014-01-01

    Full Text Available Often, freezing and startle behaviors in the context of a previously experienced stress are taken as an indication of posttraumatic stress disorder (PTSD-like symptoms in rats. However, PTSD is characterized by large individual variations of symptoms. In order to take into consideration the complex and long term distinctive variations in effects of trauma exposure additional behavioral measures are required.The current study used a novel behavioral test, the Water Associated Zero Maze (WAZM. This test was planned to enable a formation of an association between the context of the maze and an underwater trauma or swim stress in order to examine the impact of exposure to the context which immediately precedes a stressful or a traumatic experience on rat's complex behavior. Rats were exposed to the WAZM and immediately after to an underwater trauma or short swim. One month later rats were re-exposed to the context of the WAZM while their behavior was video recorded. Furthermore, c-Fos expression in the amygdala was measured 90 min after this exposure.The results of the current study indicate that the WAZM can be used to discern behavioral changes measured a long time after the actual traumatic or stressful events. Furthermore, the behavioral changes detected were accompanied by changes of c-Fos expression in the amygdala of exposed rats. We suggest that the WAZM can be used to model traumatic memories re-experiencing in rodent models of human stress-related pathologies such as PTSD.

  16. Aquaculture in artificially developed wetlands in urban areas: an application of the bivariate relationship between soil and surface water in landscape ecology.

    Science.gov (United States)

    Paul, Abhijit

    2011-01-01

    Wetlands show a strong bivariate relationship between soil and surface water. Artificially developed wetlands help to build landscape ecology and make built environments sustainable. The bheries, wetlands of eastern Calcutta (India), utilize the city sewage to develop urban aquaculture that supports the local fish industries and opens a new frontier in sustainable environmental planning research.

  17. 二元实值正交周期Box样条小波%Bivariate Real-valued Orthogonal Periodic Box-spline Wavelets

    Institute of Scientific and Technical Information of China (English)

    李强; 梁学章

    2006-01-01

    In this paper, we construct a kind of bivariate real-valued orthogonal periodic box-spline wavelets. There are only 4 terms in the two-scale dilation equations.This implies that the corresponding decomposition and reconstruction algorithms involve only 4 terms respectively which are simple in practical computation. The relation between the periodic wavelets and Fourier series is also discussed.

  18. The reliability and validity of qualitative scores for the Controlled Oral Word Association Test.

    Science.gov (United States)

    Ross, Thomas P; Calhoun, Emily; Cox, Tara; Wenner, Carolyn; Kono, Whitney; Pleasant, Morgan

    2007-05-01

    The reliability and validity of two qualitative scoring systems for the Controlled Oral Word Association Test [Benton, A. L., Hamsher, de S. K., & Sivan, A. B. (1983). Multilingual aplasia examination (2nd ed.). Iowa City, IA: AJA Associates] were examined in 108 healthy young adults. The scoring systems developed by Troyer et al. [Troyer, A. K., Moscovich, M., & Winocur, G. (1997). Clustering and switching as two components of verbal fluency: Evidence from younger and older healthy adults. Neuropsychology, 11, 138-146] and by Abwender et al. [Abwender, D. A., Swan, J. G., Bowerman, J. T., & Connolly, S. W. (2001a). Qualitative analysis of verbal fluency output: Review and comparison of several scoring methods. Assessment, 8, 323-336] each demonstrated excellent interrater reliability (all indices at or above r(icc)=.9). Consistent with previous research [e.g., Ross, T. P. (2003). The reliability of cluster and switch scores for the COWAT. Archives of Clinical Psychology, 18, 153-164), test-retest reliability coefficients (N=53; M interval 44.6 days) for the qualitative scores were modest to poor (r(icc)=.6 to .4 range). Correlations among COWAT scores, measures of executive functioning, verbal learning, working memory, and vocabulary were examined. The idea that qualitative scores represent distinct executive functions such as cognitive flexibility or strategy utilization was not supported. We offer the interpretation that COWAT performance may require the ability to retrieve words in a non-routine manner while suppressing habitual responses and associated processing interference, presumably due to a spread of activation across semantic or lexical networks. This interpretation, though speculative at present, implies that clustering and switching on the COWAT may not be entirely deliberate, but rather an artifact of a passive (i.e., state-dependent) process. Ideas for future research, most noticeably experimental studies using cognitive methods (e.g., priming), are

  19. Hydrocephalus associated with subarachnoid hemorrhage. Clinical study by computed tomography, radioisotope cisternography and constant infusion test

    Energy Technology Data Exchange (ETDEWEB)

    Nosaka, Y. (Okayama Univ. (Japan). School of Medicine)

    1981-02-01

    Thirteen patients exhibited a communicating hydrocephalus following subarachnoid hemorrhage secondary to ruptured intracranial aneurysms and were treated with shunt procedures. The interval between subarachnoid hemorrhage and surgery averaged 9 weeks. Seven of the patients showed improvement. The prognostic value for surgical management was evaluated on the basis of three different diagnostic examinations (computed tomography (CT), cisternography and constant infusion test). A correct diagnosis was obtained in 78 per cent in cisternography, and 63 per cent in infusion test and CT. All patients responding to surgery showed a typical pattern in cisternography, consisting of ventricular retention of radiopharmaceutical tracer for 48 h or longer in association with no radioactivity over the cerebral hemispheres. The constant infusion test correlated well with typical cisternographic patterns. CT is useful in demonstrating pathophysiological changes in hydrocephalus. Periventricular hypodensity was visible in patients with normal or slightly elevated intracranial pressure, accompanied by fairly rapid deterioration. All of them responded well to shunting. In most cases which benefited from the shunt, the postoperative CT showed not only normal-sized ventricles but also marked regression of the hypodensity over a short period.

  20. Hydrocephalus associated with subarachnoid hemorrhage: clinical study by computed tomography, radioisotope cisternography and constant infusion test.

    Directory of Open Access Journals (Sweden)

    Nosaka,Yoshiki

    1981-02-01

    Full Text Available Thirteen patients exhibited a communicating hydrocephalus following subarachnoid hemorrhage secondary to ruptured intracranial aneurysms and were treated with shunt procedures. The interval between subarachnoid hemorrhage and surgery averaged 9 weeks. Seven of the patients showed improvement. The prognostic value for surgical management was evaluated on the basis of three different diagnostic examinations (computed tomography(CT, cisternography and constant infusion test. A correct diagnosis was obtained in 78 per cent in cisternography, and 63 per cent in infusion test and CT. All patients responding to surgery showed a typical pattern in cisternography, consisting of ventricular retention of radiopharmaceutical tracer for 48 h or longer in association with no radioactivity over the cerebral hemispheres. The constant infusion test correlated well with typical cisternographic patterns. CT is useful in demonstrating pathophysiological changes in hydrocephalus. Periventricular hypodensity was visible in patients with normal or slightly elevated intracranial pressure, accompanied by fairly rapid deterioration. All of them responded well to shunting. In most cases which benefited from the shunt, the postoperative CT showed not only normal-sized ventricles but also marked regression of the hypodensity over a short period.

  1. Association testing of copy number variants in schizophrenia and autism spectrum disorders

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    Crespi Bernard J

    2012-05-01

    Full Text Available Abstract Background Autism spectrum disorders and schizophrenia have been associated with an overlapping set of copy number variant loci, but the nature and degree of overlap in copy number variants (deletions compared to duplications between these two disorders remains unclear. Methods We systematically evaluated three lines of evidence: (1 the statistical bases for associations of autism spectrum disorders and schizophrenia with a set of the primary CNVs thus far investigated, from previous studies; (2 data from case series studies on the occurrence of these CNVs in autism spectrum disorders, especially among children, and (3 data on the extent to which the CNVs were associated with intellectual disability and developmental, speech, or language delays. We also conducted new analyses of existing data on these CNVs in autism by pooling data from seven case control studies. Results Four of the CNVs considered, dup 1q21.1, dup 15q11-q13, del 16p11.2, and dup 22q11.21, showed clear statistical evidence as autism risk factors, whereas eight CNVs, del 1q21.1, del 3q29, del 15q11.2, del 15q13.3, dup 16p11.2, dup 16p13.1, del 17p12, and del 22q11.21, were strongly statistically supported as risk factors for schizophrenia. Three of the CNVs, dup 1q21.1, dup 16p11.2, and dup 16p13.1, exhibited statistical support as risk factors for both autism and schizophrenia, although for each of these CNVs statistical significance was nominal for tests involving one of the two disorders. For the CNVs that were statistically associated with schizophrenia but were not statistically associated with autism, a notable number of children with the CNVs have been diagnosed with autism or ASD; children with these CNVs also demonstrate a high incidence of intellectual disability and developmental, speech, or language delays. Conclusions These findings suggest that although CNV loci notably overlap between autism and schizophrenia, the degree of strongly statistically

  2. Learning from an early start but late end epidemics via an incidence rate restricted bivariate distribution and data analysis

    Directory of Open Access Journals (Sweden)

    Ramalingam Shanmugam

    2015-09-01

    Full Text Available Background: An ideal expectation of public health administrators or field medical workers is to have a late start and quick ending of any epidemic. Instead, when an epidemic starts early but ends late, it is where much can be learned from the incidences. A case in point for discussion in this article is the pattern of 2009 H1N1 epidemic. Methods: With a parameter to portray an existing health environment as a deterrent for an epidemic like H1N1 to outbreak in any location at a week, a bivariate distribution is created and is used to analyze the data for a learning so that it helps to prevent a too long prevailing future epidemic. This new distribution is named Incidence Rate Restricted Bivariate Distribution (IRRBGD. Statistical properties of IRRBGD are derived and illustrated using 2009 H1N1 incidences in all five continental regions (Africa, Asia, Europe, Americas, and Oceanic across on earth. Results: The Asian continent, compared to other four continental regions, had most vulnerability for H1N1 incidences. The odds for no H1N1 to occur is lowest only in Oceanic among the four continental regions, namely Africa, Europe, Americas, and Oceanic. Since the beginning of the year 2009 with 52 weeks, the week number, Y in which the H1N1 appeared first and the number, X of weeks the H1N1 continued on in a region are consistently highly correlated in all five continental regions. Conclusions: From the data analyses of 2009 H1N1 incidences, no continental region is risk free with respect another round of H1N1 epidemic in future. The medical community and public healthcare administrators ought to identify the common and region specific unique deterrents of the epidemic like H1N1. The impact of such deterrents to H1N1 is captured in our model and analysis. By increasing the deterrent level, the outbreak of an epidemic like H1N1 could be delayed, according to our model and data information. [Int J Res Med Sci 2015; 3(9.000: 2181-2189

  3. Auditory dysfunction associated with solvent exposure

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    Fuente Adrian

    2013-01-01

    Full Text Available Abstract Background A number of studies have demonstrated that solvents may induce auditory dysfunction. However, there is still little knowledge regarding the main signs and symptoms of solvent-induced hearing loss (SIHL. The aim of this research was to investigate the association between solvent exposure and adverse effects on peripheral and central auditory functioning with a comprehensive audiological test battery. Methods Seventy-two solvent-exposed workers and 72 non-exposed workers were selected to participate in the study. The test battery comprised pure-tone audiometry (PTA, transient evoked otoacoustic emissions (TEOAE, Random Gap Detection (RGD and Hearing-in-Noise test (HINT. Results Solvent-exposed subjects presented with poorer mean test results than non-exposed subjects. A bivariate and multivariate linear regression model analysis was performed. One model for each auditory outcome (PTA, TEOAE, RGD and HINT was independently constructed. For all of the models solvent exposure was significantly associated with the auditory outcome. Age also appeared significantly associated with some auditory outcomes. Conclusions This study provides further evidence of the possible adverse effect of solvents on the peripheral and central auditory functioning. A discussion of these effects and the utility of selected hearing tests to assess SIHL is addressed.

  4. The association between disease and profitability in individual finishing boars at a test station

    DEFF Research Database (Denmark)

    Jensen, Tina Birk; Baadsgaard, Niels Peter; Houe, Hans

    2008-01-01

    Endemic diseases in finisher herds are considered to be costly for the pig producer. We investigated the effect of diseases on the profit margin using data from a Danish boar test station (n = 5777) collected from July 2002 to December 2004. Boars reaching a target slaughter weight of at least 80......: profit margin. The results showed that treatment in the finishing period had a negative effect on the profit margin. According to the least square means estimates, boars that were treated parenterally had a reduction in the profit margin of 2.24 €. This corresponded to a reduction in the profit margin...... of 17%. Boars treated orally had a reduction of 0.88 €, which corresponded to a reduction in the profit margin of 7%. Pathological findings, breed and weight at 4 weeks were also significantly associated with the profit margin. The effect of pathological findings was influenced by breed and caused...

  5. Audiovisual crossmodal correspondences and sound symbolism: a study using the implicit association test.

    Science.gov (United States)

    Parise, Cesare V; Spence, Charles

    2012-08-01

    A growing body of empirical research on the topic of multisensory perception now shows that even non-synaesthetic individuals experience crossmodal correspondences, that is, apparently arbitrary compatibility effects between stimuli in different sensory modalities. In the present study, we replicated a number of classic results from the literature on crossmodal correspondences and highlight the existence of two new crossmodal correspondences using a modified version of the implicit association test (IAT). Given that only a single stimulus was presented on each trial, these results rule out selective attention and multisensory integration as possible mechanisms underlying the reported compatibility effects on speeded performance. The crossmodal correspondences examined in the present study all gave rise to very similar effect sizes, and the compatibility effect had a very rapid onset, thus speaking to the automatic detection of crossmodal correspondences. These results are further discussed in terms of the advantages of the IAT over traditional techniques for assessing the strength and symmetry of various crossmodal correspondences.

  6. Understanding and using the brief Implicit Association Test: recommended scoring procedures.

    Directory of Open Access Journals (Sweden)

    Brian A Nosek

    Full Text Available A brief version of the Implicit Association Test (BIAT has been introduced. The present research identified analytical best practices for overall psychometric performance of the BIAT. In 7 studies and multiple replications, we investigated analytic practices with several evaluation criteria: sensitivity to detecting known effects and group differences, internal consistency, relations with implicit measures of the same topic, relations with explicit measures of the same topic and other criterion variables, and resistance to an extraneous influence of average response time. The data transformation algorithms D outperformed other approaches. This replicates and extends the strong prior performance of D compared to conventional analytic techniques. We conclude with recommended analytic practices for standard use of the BIAT.

  7. Information Decomposition in Bivariate Systems: Theory and Application to Cardiorespiratory Dynamics

    Directory of Open Access Journals (Sweden)

    Luca Faes

    2015-01-01

    Full Text Available In the framework of information dynamics, the temporal evolution of coupled systems can be studied by decomposing the predictive information about an assigned target system into amounts quantifying the information stored inside the system and the information transferred to it. While information storage and transfer are computed through the known self-entropy (SE and transfer entropy (TE, an alternative decomposition evidences the so-called cross entropy (CE and conditional SE (cSE, quantifying the cross information and internal information of the target system, respectively. This study presents a thorough evaluation of SE, TE, CE and cSE as quantities related to the causal statistical structure of coupled dynamic processes. First, we investigate the theoretical properties of these measures, providing the conditions for their existence and assessing the meaning of the information theoretic quantity that each of them reflects. Then, we present an approach for the exact computation of information dynamics based on the linear Gaussian approximation, and exploit this approach to characterize the behavior of SE, TE, CE and cSE in benchmark systems with known dynamics. Finally, we exploit these measures to study cardiorespiratory dynamics measured from healthy subjects during head-up tilt and paced breathing protocols. Our main result is that the combined evaluation of the measures of information dynamics allows to infer the causal effects associated with the observed dynamics and to interpret the alteration of these effects with changing experimental conditions.

  8. Factors associated with HIV-testing and acceptance of an offer of home-based testing by men in rural Zambia.

    Science.gov (United States)

    Hensen, B; Lewis, J J; Schaap, A; Tembo, M; Mutale, W; Weiss, H A; Hargreaves, J; Ayles, H

    2015-03-01

    The objective of this study is to describe HIV-testing among men in rural Lusaka Province, Zambia, using a population-based survey for a cluster-randomized trial. Households (N = 120) were randomly selected from each of the 42 clusters, defined as a health facility catchment area. Individuals aged 15-60 years were invited to complete questionnaires regarding demographics and HIV-testing history. Men testing in the last year were defined as recent-testers. After questionnaire completion adults were offered home-based rapid HIV-testing. Of the 2,828 men, 53 % reported ever-testing and 25 % recently-testing. Factors independently associated with ever- and recent-testing included age 20+ years, secondary/higher education, being married or widowed, a history of TB-treatment and higher socioeconomic position. 53 % of never-testers and 57 % of men who did not report a recent-test accepted home-based HIV-testing. Current HIV-testing approaches are inadequate in this high prevalence setting. Alternative strategies, including self-testing, mobile- or workplace-testing, may be required to complement facility-based services.

  9. Comparison between different uncertainty propagation methods in multivariate analysis: An application in the bivariate case

    Energy Technology Data Exchange (ETDEWEB)

    Mullor, R. [Dpto. Estadistica e Investigacion Operativa, Universidad Alicante (Spain); Sanchez, A., E-mail: aisanche@eio.upv.e [Dpto. Estadistica e Investigacion Operativa Aplicadas y Calidad, Universidad Politecnica Valencia, Camino de Vera s/n 46022 (Spain); Martorell, S. [Dpto. Ingenieria Quimica y Nuclear, Universidad Politecnica Valencia (Spain); Martinez-Alzamora, N. [Dpto. Estadistica e Investigacion Operativa Aplicadas y Calidad, Universidad Politecnica Valencia, Camino de Vera s/n 46022 (Spain)

    2011-06-15

    Safety related systems performance optimization is classically based on quantifying the effects that testing and maintenance activities have on reliability and cost (R+C). However, R+C quantification is often incomplete in the sense that important uncertainties may not be considered. An important number of studies have been published in the last decade in the field of R+C based optimization considering uncertainties. They have demonstrated that inclusion of uncertainties in the optimization brings the decision maker insights concerning how uncertain the R+C results are and how this uncertainty does matter as it can result in differences in the outcome of the decision making process. Several methods of uncertainty propagation based on the theory of tolerance regions have been proposed in the literature depending on the particular characteristics of the variables in the output and their relations. In this context, the objective of this paper focuses on the application of non-parametric and parametric methods to analyze uncertainty propagation, which will be implemented on a multi-objective optimization problem where reliability and cost act as decision criteria and maintenance intervals act as decision variables. Finally, a comparison of results of these applications and the conclusions obtained are presented.

  10. Blunted heart rate recovery is associated with exaggerated blood pressure response during exercise testing.

    Science.gov (United States)

    Dogan, Umuttan; Duzenli, Mehmet Akif; Ozdemir, Kurtulus; Gok, Hasan

    2013-11-01

    Increased sympathetic activity and endothelial dysfunction are the proposed mechanisms underlying exaggerated blood pressure response to exercise (EBPR). However, data regarding heart rate behavior in patients with EBPR are lacking. We hypothesized that heart rate recovery (HRR) could be impaired in patients with EBPR. A total of 75 normotensive subjects who were referred for exercise treadmill test examination and experienced EBPR were included to this cross-sectional case-control study. The control group consisted of 75 age- and gender-matched normotensive subjects without EBPR. EBPR was defined as a peak exercise systolic blood pressure (BP) ≥210 mmHg in men and ≥190 mmHg in women. HRR was defined as the difference in HR from peak exercise to 1 min in recovery; abnormal HRR was defined as ≤12 beats/min. These parameters were compared with respect to occurrence of EBPR. Mean values of systolic and diastolic BP at baseline, peak exercise, and the first minute of the recovery were significantly higher in the subjects with EBPR. Mean HRR values were significantly lower (P recovery and degree of HRR in individuals without EBPR (r = 0.42, P recovery period. However, such a correlation was not found in subjects with EBPR. Our data suggest that mechanisms underlying the blunting of the HRR might be associated with the genesis of EBPR. The association between the extent of HRR and adverse cardiovascular outcomes in patients with EBPR needs to be investigated in detail in future research.

  11. Automatic processes in aesthetic judgment: Insights from the implicit association test

    Directory of Open Access Journals (Sweden)

    Pavlović Maša

    2012-01-01

    Full Text Available This study employed the Implicit Association Test (IAT with aim to examine the nature of automatic aesthetic judgment. The main hypothesis was that basic hedonic tone of artwork is one of important factors influencing automatic aesthetic evaluation. We conducted two experiments in which we varied hedonic valence of paintings of figural (Experiment 1 and abstract art (Experiment 2, measured participants’ implicit association between these paintings and evaluative attribute dimension via IAT and registered their explicit judgments of paintings’ hedonic tone. In both experiments we found that participants were significantly faster in those dual-categorization tasks in the IAT where preselected hedonically “positive” paintings were paired with the positive attributes and hedonically “negative” ones with the negative attributes than the other way around. We additionally found that explicit assessments of the hedonic tone were substantially related to the individual IAT effects in the case of abstract art, but not in the case of figural art. Implications of these findings are discussed. [Projekat Ministarstva nauke Republike Srbije, br. 179018 i br. 179033

  12. Testing circumstellar disk lifetimes in young embedded clusters associated with the Vela Molecular Ridge

    CERN Document Server

    Massi, Fabrizio; Codella, Claudio; Testi, Leonardo; Vanzi, Leonardo; Gomes, Joana

    2010-01-01

    Context. The Vela Molecular Ridge hosts a number of young embedded star clusters in the same evolutionary stage. Aims. The main aim of the present work is testing whether the fraction of members with a circumstellar disk in a sample of clusters in the cloud D of the Vela Molecular Ridge, is consistent with relations derived for larger samples of star clusters with an age spread. Besides, we want to constrain the age of the young embedded star clusters associated with cloud D. Methods. We carried out L (3.78 microns) photometry on images of six young embedded star clusters associated with cloud D of the Vela Molecular Ridge, taken with ISAAC at the VLT. These data are complemented with the available HKs photometry. The 6 clusters are roughly of the same size and appear to be in the same evolutionary stage. The fraction of stars with a circumstellar disk was measured in each cluster by counting the fraction of sources displaying a NIR excess in colour-colour (HKsL) diagrams. Results. The L photometry allowed us...

  13. Pemphigus vulgaris of the cervix: diagnostic difficulties associated with the Pap test.

    Science.gov (United States)

    Munhoz de Paula Alves Coelho, Karina; Stall, Jaqueline; Henrique Condeixa de França, Paulo; Cristina de Carvalho Tavares, Lara; Stefanello Bublitz, Giuliano; Loos, Beliza; Carvalho Costa, Luciana; Fronza Júnior, Hercílio

    2015-08-01

    Pemphigus vulgaris (PV) is a rare mucocutaneous disease caused by the abnormal production of antibodies against epithelial cell surface glycoproteins, resulting in loss of cell adhesion and intraepithelial blister formation. Cervical involvement in PV has been poorly reported, and there is little information regarding the criteria about consequential cytological changes identified in a Papanicolaou-stained cervicovaginal smear (Pap smear). Here, we report a case of PV manifesting in the cervix as well as the difficulty associated with the cytomorphological identification and interpretation of acantholytic cells. This case involved a 40-year-old patient with no history of Pap test abnormalities and no prior diagnosis of PV. In the cytological assessment, cells were identified both in isolation and in clusters that exhibited round nuclei of increased volume, inconspicuous nucleoli, and perinuclear halos. The patient underwent a cervical biopsy that revealed vesiculobullous lesions and morphological pattern consistent with PV. A skin biopsy confirmed this diagnosis. We concluded that knowledge of PV cytomorphology is important because difficulties associated with the identification and interpretation of acantholytic cells might be responsible for false positive diagnoses of cervical neoplasia. However, a suspected diagnosis of PV is possible if the cytological findings are carefully correlated with the clinical data.

  14. Drilling and Production Testing the Methane Hydrate Resource Potential Associated with the Barrow Gas Fields

    Energy Technology Data Exchange (ETDEWEB)

    Steve McRae; Thomas Walsh; Michael Dunn; Michael Cook

    2010-02-22

    In November of 2008, the Department of Energy (DOE) and the North Slope Borough (NSB) committed funding to develop a drilling plan to test the presence of hydrates in the producing formation of at least one of the Barrow Gas Fields, and to develop a production surveillance plan to monitor the behavior of hydrates as dissociation occurs. This drilling and surveillance plan was supported by earlier studies in Phase 1 of the project, including hydrate stability zone modeling, material balance modeling, and full-field history-matched reservoir simulation, all of which support the presence of methane hydrate in association with the Barrow Gas Fields. This Phase 2 of the project, conducted over the past twelve months focused on selecting an optimal location for a hydrate test well; design of a logistics, drilling, completion and testing plan; and estimating costs for the activities. As originally proposed, the project was anticipated to benefit from industry activity in northwest Alaska, with opportunities to share equipment, personnel, services and mobilization and demobilization costs with one of the then-active exploration operators. The activity level dropped off, and this benefit evaporated, although plans for drilling of development wells in the BGF's matured, offering significant synergies and cost savings over a remote stand-alone drilling project. An optimal well location was chosen at the East Barrow No.18 well pad, and a vertical pilot/monitoring well and horizontal production test/surveillance well were engineered for drilling from this location. Both wells were designed with Distributed Temperature Survey (DTS) apparatus for monitoring of the hydrate-free gas interface. Once project scope was developed, a procurement process was implemented to engage the necessary service and equipment providers, and finalize project cost estimates. Based on cost proposals from vendors, total project estimated cost is $17.88 million dollars, inclusive of design work

  15. Landslide susceptibility mapping using a bivariate statistical model in a tropical hilly area of southeastern Brazil

    Science.gov (United States)

    Araújo, J. P. C.; DA Silva, L. M.; Dourado, F. A. D.; Fernandes, N.

    2015-12-01

    Landslides are the most damaging natural hazard in the mountainous region of Rio de Janeiro State in Brazil, responsible for thousands of deaths and important financial and environmental losses. However, this region has currently few landslide susceptibility maps implemented on an adequate scale. Identification of landslide susceptibility areas is fundamental in successful land use planning and management practices to reduce risk. This paper applied the Bayes' theorem based on weight of evidence (WoE) using 8 landslide-related factors in a geographic information system (GIS) for landslide susceptibility mapping. 378 landslide locations were identified and mapped on a selected basin in the city of Nova Friburgo, triggered by the January 2011 rainfall event. The landslide scars were divided into two subsets: training and validation subsets. The 8 landslide-related factors weighted by WoE were performed using chi-square test to indicate which variables are conditionally independent of each other to be used in the final map. Finally, the maps of weighted factors were summed up to construct the landslide susceptibility map and validated by the validation landslide subset. According to the results, slope, aspect and contribution area showed the higher positive spatial correlation with landslides. In the landslide susceptibility map, 21% of the area presented very low and low susceptibilities with 3% of the validation scars, 41% presented medium susceptibility with 22% of the validation scars and 38% presented high and very high susceptibilities with 75% of the validation scars. The very high susceptibility class stands for 16% of the basin area and has 54% of the all scars. The approach used in this study can be considered very useful since 75% of the area affected by landslides was included in the high and very high susceptibility classes.

  16. Implicit Association Test: a possible tool for screening patients for orthognathic surgery.

    Science.gov (United States)

    Yu, Dedong; Fang, Bing; Wang, Fang; Wang, Xudong; Zhang, Wenbin; Dai, Jiewen; Shen, Steve G F

    2013-08-01

    In orthognathic surgery, many serious medical disputes and postsurgical dissatisfactions are not caused by the doctors' reasons, but due to the patients' psychological problems. These adverse events obsess not only surgeons, but also patients to a great extent. An effective method is expected to screen patients for orthognathic surgery. So far, most selecting approaches in orthognathic surgery are based on explicit cognition, which inevitably include the following faults: patients' intentional concealment, uncertain errors, and imprecise subjective judgment from the doctors. However, these errors can be avoided by the tests based on implicit cognition, i.e., Implicit Association Test (IAT). Avoiding the faults of explicit cognition, IAT is an objective, quantitative, and easily applicable mental measurement method. We hypothesized that all the patients for orthognathic purpose should have an IAT screening before treatment. By IAT method, the right patients for orthognathic surgery can be picked out. As a result, postoperative dissatisfaction, medical dispute, and even violent conflict can be avoided to a great extent. To the best of our knowledge, there is no relevant report on the use of IAT as a tool to select the right orthognathic patients to avoid postsurgical dissatisfaction, medical disputes and violent conflict events.

  17. Association between cervical lesion grade and micronucleus frequency in the Papanicolaou test

    Directory of Open Access Journals (Sweden)

    Caroline Tanski Bueno

    2014-09-01

    Full Text Available The aim of this study was to evaluate the association between the frequency of micronuclei (MN and the cellular changes detected in the conventional Papanicolaou test. One hundred and seventy-four Papanicolaou test smears with cellular changes were examined. MN screening was done in cytopathological smears by counting 1,000 cervical cells in a light microscope. MN frequencies were significantly higher in the group with cellular changes compared to the control group (p < 0.001. The mean MN frequencies were 0.95 ± 1.12 (mean ± SD in the control group (n = 223, 2.98 ± 1.20 in individuals with atypical squamous cells of undetermined significance (ASC-US (n = 50, 4.04 ± 1.45 in cervical intraepithelial neoplasia (CIN I (n = 52, 5.97 ± 1.83 in CIN II (n = 30, 7.29 ± 1.55 in CIN III (n = 17 and 8.64 ± 1.55 in invasive cancer (n = 25. These findings suggest that MN monitoring should be included as an additional criterion for the early detection of cytogenetic damage in routine examinations. This monitoring should be done in the same smear as used for cytopathological examination. More specific and systematic studies are necessary to confirm this proposal.

  18. Association between micronucleus frequency and cervical intraepithelial neoplasia grade in Thinprep cytological test and its significance.

    Science.gov (United States)

    Shi, Yong-Hua; Wang, Bo-Wei; Tuokan, Talaf; Li, Qiao-Zhi; Zhang, Ya-Jing

    2015-01-01

    A micronucleus is an additional small nucleus formed due to chromosomes or chromosomal fragments fail to be incorporated into the nucleus during cell division. In this study, we assessed the utility of micronucleus counting as a screening tool in cervical precancerous lesions in Thinprep cytological test smears under oil immersion. High risk HPV was also detected by hybrid capture-2 in Thinprep cytological test smears. Our results showed that micronucleus counting was significantly higher in high-grade squamous intraepithelial lesion (HSIL) and invasive carcinoma cases compared to low-grade squamous intraepithelial lesion (LSIL) and non-neoplastic cases. Receiver operating characteristic (ROC) curve analysis revealed that micronucleus counting possessed a high degree of sensitivity and specificity for identifying HSIL and invasive carcinoma. Cut-off of 7.5 for MN counting gave a sensitivity of 89.6% and a specificity of 66.7% (P = 0.024 and AUC = 0.892) for detecting HSIL and invasive carcinoma lesions. Multiple linear regression analysis showed that only HSIL and invasive cancer lesions not age, duration of marital life and number of pregnancy are significantly associated with MN counting. The positive rate of high risk HPV was distinctly higher in LSIL, HSIL and invasive cancer than that in non-neoplstic categories. In conclusions, MN evaluation may be viewed as an effective biomarker for cervical cancer screening. The combination of MN count with HPV DNA detection and TCT may serve as an effective means to screen precancerous cervical lesions in most developing nations.

  19. Association between cervical lesion grade and micronucleus frequency in the Papanicolaou test.

    Science.gov (United States)

    Bueno, Caroline Tanski; Dornelles da Silva, Cláudia Maria; Barcellos, Regina Bones; da Silva, Juliana; Dos Santos, Carla Rossana; Menezes, João Evangelista Sampaio; Menezes, Honório Sampaio; Rossetti, Maria Lucia Rosa

    2014-09-01

    The aim of this study was to evaluate the association between the frequency of micronuclei (MN) and the cellular changes detected in the conventional Papanicolaou test. One hundred and seventy-four Papanicolaou test smears with cellular changes were examined. MN screening was done in cytopathological smears by counting 1,000 cervical cells in a light microscope. MN frequencies were significantly higher in the group with cellular changes compared to the control group (p < 0.001). The mean MN frequencies were 0.95 ± 1.12 (mean ± SD) in the control group (n = 223), 2.98 ± 1.20 in individuals with atypical squamous cells of undetermined significance (ASC-US) (n = 50), 4.04 ± 1.45 in cervical intraepithelial neoplasia (CIN) I (n = 52), 5.97 ± 1.83 in CIN II (n = 30), 7.29 ± 1.55 in CIN III (n = 17) and 8.64 ± 1.55 in invasive cancer (n = 25). These findings suggest that MN monitoring should be included as an additional criterion for the early detection of cytogenetic damage in routine examinations. This monitoring should be done in the same smear as used for cytopathological examination. More specific and systematic studies are necessary to confirm this proposal.

  20. Prevalence of Orthorexia nervosa among college students based on Bratman's test and associated tendencies.

    Science.gov (United States)

    Bundros, Joanna; Clifford, Dawn; Silliman, Kathryn; Neyman Morris, Michelle

    2016-06-01

    Disordered eating is prevalent among college student populations, and Orthorexia nervosa (ON) is being explored as a new type of eating disorder. There is currently no standardized ON diagnostic tool, and the majority of ON research has been conducted among European populations. The present study explored the Bratman Orthorexia Test (BOT) for ON diagnosis, and its relationship to validated tools for assessing disordered eating, body dysmorphic, and obsessive-compulsive tendencies among college students attending a western university. A convenience sample of 448 college students with a mean age of 22 years was recruited to complete an online survey that included the BOT, Eating Attitudes Test-26 (EAT-26), Body Dysmorphic Disorder Questionnaire (BDDQ), Obsessive Compulsive Inventory, Revised (OCI-R) and demographics. Spearman correlation, Mann-Whitney U, Kruskal-Wallis, chi-square, and multiple linear regressions were used for analyses. The average BOT score was 4.71, near the "health fanatic" range, with Hispanic/Latino subjects and overweight/obese students having significantly higher median BOT scores. Gender, age, and college major were not significantly associated with BOT score. Significant positive correlations were observed between total BOT and EAT-26 scores (r = .47, p college students and Hispanic/Latino and overweight/obese students may be at increased risk. Further research is needed to determine ON risk factors among diverse student populations in order to inform prevention and treatment approaches on college campuses.

  1. A stochastic inference of de novo CNV detection and association test in multiplex schizophrenia families

    Directory of Open Access Journals (Sweden)

    Shi-Heng eWang

    2013-09-01

    Full Text Available The copy number variation (CNV is a type of genetic variation in the genome. It is measured based on signal intensity measures and can be assessed repeatedly to reduce the uncertainty in PCR-based typing. Studies have shown that CNVs may lead to phenotypic variation and modification of disease expression. Various challenges exist, however, in the exploration of CNV-disease association. Here we construct latent variables to infer the discrete CNV values and to estimate the probability of mutations. In addition, we propose to pool rare variants to increase the statistical power and we conduct family studies to mitigate the computational burden in determining the composition of CNVs on each chromosome. The aim is to explore in a stochastic sense the association between the collapsing CNV variants and disease status with a Bayesian hierarchical model. This model assigns integers in a probabilistic sense to the quantitatively measured copy numbers, and is able to test simultaneously the association for all variants of interest in a regression framework. This integrative model can account for the uncertainty in copy number assignment and differentiate if the variation was de novo or inherited on the basis of posterior probabilities. For family studies, this model can accommodate the dependence within family members and among repeated CNV data. Moreover, the Mendelian rule can be assumed under this model and yet the genetic variation, including de novo and inherited variation, can still be included and quantified directly for each individual. Finally, simulation studies show that this model has high true positive and low false positive rates in the detection of de novo mutation.

  2. GIS-Based and Data-Driven Bivariate Landslide-Susceptibility Mapping in the Three Gorges Area, China

    Institute of Scientific and Technical Information of China (English)

    BAI Shi-Biao; WANG Jian; L(U) Guo-Nian; ZHOU Ping-Gen; HOU Sheng-Shan; XU Su-Ning

    2009-01-01

    A detailed landslide-susceptibility map was produced using a data-driven objective bivariate analysis method with datasets developed for a geographic information system (CIS). Known as one of the most landslide-prone areas in China, the Zhongxian-Shizhu Segment in the Three Gorges Reservoir region of China was selected as a suitable case because of the frequency and distribution of landslides. The site covered an area of 260.93 km2 with a landslide area of 5.32 km2. Four data domains were used in this study, including remote sensing products, thematic maps, geological maps, and topographical maps, all with 25 m × 25 m pixels. Statistical relationships for landslide susceptibility were developed using landslide and landslide causative factor databases. All continuous variables were converted to categorical variables according to the percentile divisions of seed cells, and the corresponding class weight values were calculated and summed to create the susceptibility map. According to the map, 3.6% of the study area was identified as high-susceptibility. Extremely low-, very low-, low-, and medium-susceptibility zones covered 19.66%, 31.69%, 27.95%, and 17.1% of the area, respectively. The high- and medium-hazardous zones are along both sides of the Yangtze River, being in agreement with the actual distribution of landslides.

  3. Technology-enhanced Interactive Teaching of Marginal, Joint and Conditional Probabilities: The Special Case of Bivariate Normal Distribution.

    Science.gov (United States)

    Dinov, Ivo D; Kamino, Scott; Bhakhrani, Bilal; Christou, Nicolas

    2013-01-01

    Data analysis requires subtle probability reasoning to answer questions like What is the chance of event A occurring, given that event B was observed? This generic question arises in discussions of many intriguing scientific questions such as What is the probability that an adolescent weighs between 120 and 140 pounds given that they are of average height? and What is the probability of (monetary) inflation exceeding 4% and housing price index below 110? To address such problems, learning some applied, theoretical or cross-disciplinary probability concepts is necessary. Teaching such courses can be improved by utilizing modern information technology resources. Students' understanding of multivariate distributions, conditional probabilities, correlation and causation can be significantly strengthened by employing interactive web-based science educational resources. Independent of the type of a probability course (e.g. majors, minors or service probability course, rigorous measure-theoretic, applied or statistics course) student motivation, learning experiences and knowledge retention may be enhanced by blending modern technological tools within the classical conceptual pedagogical models. We have designed, implemented and disseminated a portable open-source web-application for teaching multivariate distributions, marginal, joint and conditional probabilities using the special case of bivariate Normal distribution. A real adolescent height and weight dataset is used to demonstrate the classroom utilization of the new web-application to address problems of parameter estimation, univariate and multivariate inference.

  4. Cerebral correlates of faking: Evidence from a Brief Implicit Association Test on Doping Attitudes

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    Sebastian eSchindler

    2015-05-01

    Full Text Available Direct assessment of attitudes toward socially sensitive topics can be affected by deception attempts. Reaction-time based indirect measures, such as the Implicit Association Test (IAT, are less susceptible to such biases. Neuroscientific evidence shows that deception can evoke characteristic ERP differences. However, the cerebral processes involved in faking an IAT are still unknown. We randomly assigned 20 university students (15 females, 24.65 ± 3.50 years of age to a counterbalanced repeated-measurements design, requesting them to complete a Brief-IAT (BIAT on attitudes toward doping without deception instruction, and with the instruction to fake positive and negative doping attitudes. Cerebral activity during BIAT completion was assessed using high-density EEG. Event-related potentials during faking revealed enhanced frontal and reduced occipital negativity, starting around 150ms after stimulus presentation. Further, a decrease in the P300 and LPP components was observed. Source analyses showed enhanced activity in the right inferior frontal gyrus between 150 and 200ms during faking, thought to reflect the suppression of automatic responses. Further, more activity was found for faking in the bilateral middle occipital gyri and the bilateral temporoparietal junction. Results indicate that faking reaction-time based tests alter brain processes from early stages of processing and reveal the cortical sources of the effects. Analyzing the EEG helps to uncover response patterns in indirect attitude tests and broadens our understanding of the neural processes involved in such faking. This knowledge might be useful for uncovering faking in socially sensitive contexts, where attitudes are likely to be concealed.

  5. Genetic testing for TMEM154 mutations associated with lentivirus susceptibility in sheep.

    Directory of Open Access Journals (Sweden)

    Michael P Heaton

    Full Text Available In sheep, small ruminant lentiviruses cause an incurable, progressive, lymphoproliferative disease that affects millions of animals worldwide. Known as ovine progressive pneumonia virus (OPPV in the U.S., and Visna/Maedi virus (VMV elsewhere, these viruses reduce an animal's health, productivity, and lifespan. Genetic variation in the ovine transmembrane protein 154 gene (TMEM154 has been previously associated with OPPV infection in U.S. sheep. Sheep with the ancestral TMEM154 haplotype encoding glutamate (E at position 35, and either form of an N70I variant, were highly-susceptible compared to sheep homozygous for the K35 missense mutation. Our current overall aim was to characterize TMEM154 in sheep from around the world to develop an efficient genetic test for reduced susceptibility. The average frequency of TMEM154 E35 among 74 breeds was 0.51 and indicated that highly-susceptible alleles were present in most breeds around the world. Analysis of whole genome sequences from an international panel of 75 sheep revealed more than 1,300 previously unreported polymorphisms in a 62 kb region containing TMEM154 and confirmed that the most susceptible haplotypes were distributed worldwide. Novel missense mutations were discovered in the signal peptide (A13V and the extracellular domains (E31Q, I74F, and I102T of TMEM154. A matrix-assisted laser desorption/ionization-time-of flight mass spectrometry (MALDI-TOF MS assay was developed to detect these and six previously reported missense and two deletion mutations in TMEM154. In blinded trials, the call rate for the eight most common coding polymorphisms was 99.4% for 499 sheep tested and 96.0% of the animals were assigned paired TMEM154 haplotypes (i.e., diplotypes. The widespread distribution of highly-susceptible TMEM154 alleles suggests that genetic testing and selection may improve the health and productivity of infected flocks.

  6. Implicit and explicit attitudes towards conventional and complementary and alternative medicine treatments: Introduction of an Implicit Association Test.

    Science.gov (United States)

    Green, James A; Hohmann, Cynthia; Lister, Kelsi; Albertyn, Riani; Bradshaw, Renee; Johnson, Christine

    2016-06-01

    This study examined associations between anticipated future health behaviour and participants' attitudes. Three Implicit Association Tests were developed to assess safety, efficacy and overall attitude. They were used to examine preference associations between conventional versus complementary and alternative medicine among 186 participants. A structural equation model suggested only a single implicit association, rather than three separate domains. However, this single implicit association predicted additional variance in anticipated future use of complementary and alternative medicine beyond explicit. Implicit measures should give further insight into motivation for complementary and alternative medicine use.

  7. Perceived characteristics of the environment associated with active travel: development and testing of a new scale

    Directory of Open Access Journals (Sweden)

    Mutrie Nanette

    2008-05-01

    Full Text Available Abstract Background Environmental characteristics may be associated with patterns of physical activity. However, the development of instruments to measure perceived characteristics of the local environment is still at a comparatively early stage, and published instruments are not necessarily suitable for application in all settings. We therefore developed and established the test-retest reliability of a new scale for use in a study of the correlates of active travel and overall physical activity in deprived urban neighbourhoods in Glasgow, Scotland. Methods We developed and piloted a 14-item scale based on seven constructs identified from the literature (aesthetics, green space, access to amenities, convenience of routes, traffic, road safety and personal safety. We administered the scale to all participants in a random postal survey (n = 1322 and readministered the scale to a subset of original respondents (n = 125 six months later. We used principal components analysis and Varimax rotation to identify three principal components (factors and derived summary scores for subscales based on these factors. We examined the internal consistency of these subscales using Cronbach's alpha and examined the test-retest reliability of the individual items, the subscale summary scores and an overall summary neighbourhood score using a combination of correlation coefficients and Cohen's kappa with and without weighting. Results Public transport and proximity to shops were the items most likely to be rated positively, whereas traffic volume, traffic noise and road safety for cyclists were most likely to be rated negatively. Three principal components – 'safe and pleasant surroundings', 'low traffic' and 'convenience for walking' – together explained 45% of the total variance. The test-retest reliability of individual items was comparable with that of items in other published scales (intraclass correlation coefficients (ICCs 0.34–0.70; weighted Cohen

  8. Are Child Abusers Sexually Attracted to Submissiveness? Assessment of Sex-Related Cognition With the Implicit Association Test

    NARCIS (Netherlands)

    Kanters, Thijs; Hornsveld, Ruud H J; Nunes, Kevin L.; Huijding, Jorg; Zwets, Almar J.; Snowden, Robert J.; Muris, Peter; van Marle, Hjalmar J C

    2016-01-01

    Child sexual abuse is associated with social anxiety, low self-esteem, and intimacy deficits. This, in combination with the core belief of a dangerous world, might suggest that child abusers are sexually attracted to submissiveness. The Implicit Association Test (IAT) was used to examine this hypoth

  9. A general approach for combining diverse rare variant association tests provides improved robustness across a wider range of genetic architectures.

    Science.gov (United States)

    Greco, Brian; Hainline, Allison; Arbet, Jaron; Grinde, Kelsey; Benitez, Alejandra; Tintle, Nathan

    2016-05-01

    The widespread availability of genome sequencing data made possible by way of next-generation technologies has yielded a flood of different gene-based rare variant association tests. Most of these tests have been published because they have superior power for particular genetic architectures. However, for applied researchers it is challenging to know which test to choose in practice when little is known a priori about genetic architecture. Recently, tests have been proposed which combine two particular individual tests (one burden and one variance components) to minimize power loss while improving robustness to a wider range of genetic architectures. In our analysis we propose an expansion of these approaches, yielding a general method that works for combining any number of individual tests. We demonstrate that running multiple different tests on the same data set and using a Bonferroni correction for multiple testing is never better than combining tests using our general method. We also find that using a test statistic that is highly robust to the inclusion of non-causal variants (joint-infinity) together with a previously published combined test (sequence kernel adaptive test-optimal) provides improved robustness to a wide range of genetic architectures and should be considered for use in practice. Software for this approach is supplied. We support the increased use of combined tests in practice - as well as further exploration of novel combined testing approaches using the general framework provided here - to maximize robustness of rare variant testing strategies against a wide range of genetic architectures.

  10. A new powerful non-parametric two-stage approach for testing multiple phenotypes in family-based association studies

    NARCIS (Netherlands)

    Lange, C; Lyon, H; DeMeo, D; Raby, B; Silverman, EK; Weiss, ST

    2003-01-01

    We introduce a new powerful nonparametric testing strategy for family-based association studies in which multiple quantitative traits are recorded and the phenotype with the strongest genetic component is not known prior to the analysis. In the first stage, using a population-based test based on the

  11. Factors Associated with Recent HIV Testing among Heterosexuals at High-Risk for HIV Infection in New York City

    Directory of Open Access Journals (Sweden)

    Marya eGwadz

    2016-04-01

    Full Text Available Background. The CDC recommends persons at high-risk for HIV infection in the United States receive annual HIV testing to foster early HIV diagnosis and timely linkage to health care. Heterosexuals make up a significant proportion of incident HIV infections (>25%, but test for HIV less frequently than those in other risk categories. Yet factors that promote or impede annual HIV testing among heterosexuals are poorly understood. The present study examines individual/attitudinal-, social-, and structural-level factors associated with past-year HIV testing among heterosexuals at high-risk for HIV. Methods. Participants were African American/Black and Hispanic heterosexual adults (N=2307 residing in an urban area with both high poverty and HIV prevalence rates. Participants were recruited by respondent-driven sampling (RDS in 2012-2015 and completed a computerized structured assessment battery covering background factors, multi-level putative facilitators of HIV testing, and HIV testing history. Separate logistic regression analysis for males and females identified factors associated with past-year HIV testing.Results. Participants were mostly male (58%, African American/Black (75%, and 39 years old on average (SD = 12.06 years. Lifetime homelessness (54% and incarceration (62% were common. Half reported past-year HIV testing (50% and 37% engaged in regular, annual HIV testing. Facilitators of HIV testing common to both genders included sexually transmitted infection (STI testing or STI diagnosis, peer norms supporting HIV testing, and HIV testing access. Among women, access to general medical care and extreme poverty further predicted HIV testing, while recent drug use reduced the odds of past-year HIV testing. Among men, past-year HIV testing was also associated with lifetime incarceration and substance use treatment.Conclusions. The present study identified gaps in rates of HIV testing among heterosexuals at high-risk for HIV, and both common and

  12. The frequency of missed test results and associated treatment delays in a highly computerized health system

    Science.gov (United States)

    Wahls, Terry L; Cram, Peter M

    2007-01-01

    Background: Diagnostic errors associated with the failure to follow up on abnormal diagnostic studies ("missed results") are a potential cause of treatment delay and a threat to patient safety. Few data exist concerning the frequency of missed results and associated treatment delays within the Veterans Health Administration (VA). Objective: The primary objective of the current study was to assess the frequency of missed results and resulting treatment delays encountered by primary care providers in VA clinics. Methods: An anonymous on-line survey of primary care providers was conducted as part of the health systems ongoing quality improvement programs. We collected information from providers concerning their clinical effort (e.g., number of clinic sessions, number of patient visits per session), number of patients with missed abnormal test results, and the number and types of treatment delays providers encountered during the two week period prior to administration of our survey. Results: The survey was completed by 106 out of 198 providers (54 percent response rate). Respondents saw and average of 86 patients per 2 week period. Providers encountered 64 patients with missed results during the two week period leading up to the study and 52 patients with treatment delays. The most common missed results included imaging studies (29 percent), clinical laboratory (22 percent), anatomic pathology (9 percent), and other (40 percent). The most common diagnostic delays were cancer (34 percent), endocrine problems (26 percent), cardiac problems (16 percent), and others (24 percent). Conclusion: Missed results leading to clinically important treatment delays are an important and likely underappreciated source of diagnostic error. PMID:17519017

  13. The frequency of missed test results and associated treatment delays in a highly computerized health system

    Directory of Open Access Journals (Sweden)

    Wahls Terry L

    2007-05-01

    Full Text Available Abstract Background: Diagnostic errors associated with the failure to follow up on abnormal diagnostic studies ("missed results" are a potential cause of treatment delay and a threat to patient safety. Few data exist concerning the frequency of missed results and associated treatment delays within the Veterans Health Administration (VA. Objective: The primary objective of the current study was to assess the frequency of missed results and resulting treatment delays encountered by primary care providers in VA clinics. Methods: An anonymous on-line survey of primary care providers was conducted as part of the health systems ongoing quality improvement programs. We collected information from providers concerning their clinical effort (e.g., number of clinic sessions, number of patient visits per session, number of patients with missed abnormal test results, and the number and types of treatment delays providers encountered during the two week period prior to administration of our survey. Results: The survey was completed by 106 out of 198 providers (54 percent response rate. Respondents saw and average of 86 patients per 2 week period. Providers encountered 64 patients with missed results during the two week period leading up to the study and 52 patients with treatment delays. The most common missed results included imaging studies (29 percent, clinical laboratory (22 percent, anatomic pathology (9 percent, and other (40 percent. The most common diagnostic delays were cancer (34 percent, endocrine problems (26 percent, cardiac problems (16 percent, and others (24 percent. Conclusion: Missed results leading to clinically important treatment delays are an important and likely underappreciated source of diagnostic error.

  14. Association studies with imputed variants using expectation-maximization likelihood-ratio tests.

    Directory of Open Access Journals (Sweden)

    Kuan-Chieh Huang

    Full Text Available Genotype imputation has become standard practice in modern genetic studies. As sequencing-based reference panels continue to grow, increasingly more markers are being well or better imputed but at the same time, even more markers with relatively low minor allele frequency are being imputed with low imputation quality. Here, we propose new methods that incorporate imputation uncertainty for downstream association analysis, with improved power and/or computational efficiency. We consider two scenarios: I when posterior probabilities of all potential genotypes are estimated; and II when only the one-dimensional summary statistic, imputed dosage, is available. For scenario I, we have developed an expectation-maximization likelihood-ratio test for association based on posterior probabilities. When only imputed dosages are available (scenario II, we first sample the genotype probabilities from its posterior distribution given the dosages, and then apply the EM-LRT on the sampled probabilities. Our simulations show that type I error of the proposed EM-LRT methods under both scenarios are protected. Compared with existing methods, EM-LRT-Prob (for scenario I offers optimal statistical power across a wide spectrum of MAF and imputation quality. EM-LRT-Dose (for scenario II achieves a similar level of statistical power as EM-LRT-Prob and, outperforms the standard Dosage method, especially for markers with relatively low MAF or imputation quality. Applications to two real data sets, the Cebu Longitudinal Health and Nutrition Survey study and the Women's Health Initiative Study, provide further support to the validity and efficiency of our proposed methods.

  15. Effects of computer-based immediate feedback on foreign language listening comprehension and test-associated anxiety.

    Science.gov (United States)

    Lee, Shu-Ping; Su, Hui-Kai; Lee, Shin-Da

    2012-06-01

    This study investigated the effects of immediate feedback on computer-based foreign language listening comprehension tests and on intrapersonal test-associated anxiety in 72 English major college students at a Taiwanese University. Foreign language listening comprehension of computer-based tests designed by MOODLE, a dynamic e-learning environment, with or without immediate feedback together with the state-trait anxiety inventory (STAI) were tested and repeated after one week. The analysis indicated that immediate feedback during testing caused significantly higher anxiety and resulted in significantly higher listening scores than in the control group, which had no feedback. However, repeated feedback did not affect the test anxiety and listening scores. Computer-based immediate feedback did not lower debilitating effects of anxiety but enhanced students' intrapersonal eustress-like anxiety and probably improved their attention during listening tests. Computer-based tests with immediate feedback might help foreign language learners to increase attention in foreign language listening comprehension.

  16. Testing Students with Special Educational Needs in Large-Scale Assessments - Psychometric Properties of Test Scores and Associations with Test Taking Behavior.

    Science.gov (United States)

    Pohl, Steffi; Südkamp, Anna; Hardt, Katinka; Carstensen, Claus H; Weinert, Sabine

    2016-01-01

    Assessing competencies of students with special educational needs in learning (SEN-L) poses a challenge for large-scale assessments (LSAs). For students with SEN-L, the available competence tests may fail to yield test scores of high psychometric quality, which are-at the same time-measurement invariant to test scores of general education students. We investigated whether we can identify a subgroup of students with SEN-L, for which measurement invariant competence measures of adequate psychometric quality may be obtained with tests available in LSAs. We furthermore investigated whether differences in test-taking behavior may explain dissatisfying psychometric properties and measurement non-invariance of test scores within LSAs. We relied on person fit indices and mixture distribution models to identify students with SEN-L for whom test scores with satisfactory psychometric properties and measurement invariance may be obtained. We also captured differences in test-taking behavior related to guessing and missing responses. As a result we identified a subgroup of students with SEN-L for whom competence scores of adequate psychometric quality that are measurement invariant to those of general education students were obtained. Concerning test taking behavior, there was a small number of students who unsystematically picked response options. Removing these students from the sample slightly improved item fit. Furthermore, two different patterns of missing responses were identified that explain to some extent problems in the assessments of students with SEN-L.

  17. Simplifying consent for HIV testing is associated with an increase in HIV testing and case detection in highest risk groups, San Francisco January 2003-June 2007.

    Directory of Open Access Journals (Sweden)

    Nicola M Zetola

    Full Text Available BACKGROUND: Populations at highest risk for HIV infection face multiple barriers to HIV testing. To facilitate HIV testing procedures, the San Francisco General Hospital Medical Center eliminated required written patient consent for HIV testing in its medical settings in May 2006. To describe the change in HIV testing rates in different hospital settings and populations after the change in HIV testing policy in the SFDH medical center, we performed an observational study using interrupted time series analysis. METHODS: Data from all patients aged 18 years and older seen from January 2003 through June 2007 at the San Francisco Department of Public Health (SFDPH medical care system were included in the analysis. The monthly HIV testing rate per 1000 had patient-visits was calculated for the overall population and stratified by hospital setting, age, sex, race/ethnicity, homelessness status, insurance status and primary language. RESULTS: By June 2007, the average monthly rate of HIV tests per 1000 patient-visits increased 4.38 (CI, 2.17-6.60, p<0.001 over the number predicted if the policy change had not occurred (representing a 44% increase. The monthly average number of new positive HIV tests increased from 8.9 (CI, 6.3-11.5 to 14.9 (CI, 10.6-19.2, p<0.001, representing a 67% increase. Although increases in HIV testing were seen in all populations, populations at highest risk for HIV infection, particularly men, the homeless, and the uninsured experienced the highest increases in monthly HIV testing rates after the policy change. CONCLUSIONS: The elimination of the requirement for written consent in May 2006 was associated with a significant and sustained increase in HIV testing rates and HIV case detection in the SFDPH medical center. Populations facing the higher barriers to HIV testing had the highest increases in HIV testing rates and case detection in response to the policy change.

  18. Test

    DEFF Research Database (Denmark)

    Bendixen, Carsten

    2014-01-01

    Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers.......Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers....

  19. Factors associated with not testing for HIV and consistent condom use among men in Soweto, South Africa.

    Directory of Open Access Journals (Sweden)

    Sakhile Mhlongo

    Full Text Available BACKGROUND: Besides access to medical male circumcision, HIV testing, access to condoms and consistent condom use are additional strategies men can use to prevent HIV acquisition. We examine male behavior toward testing and condom use. OBJECTIVE: To determine factors associated with never testing for HIV and consistent condom use among men who never test in Soweto. METHODS: A cross-sectional survey in Soweto was conducted in 1539 men aged 18-32 years in 2007. Data were collected on socio-demographic and behavioral characteristics to determine factors associated with not testing and consistent condom use. RESULTS: Over two thirds (71% of men had not had an HIV test and the majority (55%, n = 602 were young (18-23. Of those not testing, condom use was poor (44%, n = 304. Men who were 18-23 years (aOR: 2.261, CI: 1.534-3.331, with primary (aOR: 2.096, CI: 1.058-4.153 or high school (aOR: 1.622, CI: 1.078-2.439 education, had sex in the last 6 months (aOR: 1.703, CI: 1.055-2.751, and had ≥1 sexual partner (aOR: 1.749, CI: 1.196-2.557 were more likely not to test. Of those reporting condom use (n = 1036, 67%, consistent condom use was 43% (n = 451. HIV testing did not correlate with condom use. CONCLUSION: Low rates of both condom use and HIV testing among men in a high HIV prevalence setting are worrisome and indicate an urgent need to develop innovative behavioral strategies to address this shortfall. Condom use is poor in this population whether tested or not tested for HIV, indicating no association between condom use and HIV testing.

  20. Visual association test to detect early dementia of the Alzheimer type

    Science.gov (United States)

    Lindeboom, J; Schmand, B; Tulner, L; Walstra, G; Jonker, C

    2002-01-01

    Background: The visual association test (VAT) is a brief learning task based on imagery mnemonics. The test materials consist of six line drawings of pairs of interacting objects or animals—for example, an ape holding an umbrella. The person is asked to name each object and, later, is presented with one object from the pair and asked to name the other. Objective: To verify that the task induces robust incidental or effortless learning (study 1), and to study the efficiency of the test as a discriminator between early dementia of the Alzheimer type (DAT) and non-demented people (study 2) and non-DAT types of dementia (study 3). Methods: Study 1: two groups of elderly volunteers were administered the VAT. The stimuli were presented in the interactive fashion to group A—for example, a monkey carrying an umbrella (n=83)—and side by side to group B—for example, separate pictures of a monkey alone and an umbrella alone (n=79). Group B received learning instructions, but group A did not. Study 2: three groups of subjects were selected from a population based follow up study: incident DAT cases (n=24), cognitively declining subjects not diagnosed with dementia (n=21), and stable non-demented subjects (n=204). Test performance of the non-demented group at baseline was compared with that of patients with DAT at the time of their diagnosis, of patients with DAT a year before their diagnosis, and of non-demented declining subjects at baseline. Study 3: subjects were patients referred for neuropsychological assessment because of suspected dementia. They were diagnosed by consensus criteria of various dementia syndromes. Results: Study 1: recall was more than twice as high in group A as in group B. Thus interactive presentation, even in the absence of learning instructions, enhances learning. Study 2: at a level of 97.5% specificity, the VAT had a sensitivity of 87.5% for DAT cases at the time of diagnosis and 66.7% one year before diagnosis. The cognitively declining

  1. Indirect measurement of motivation: Developing and testing a motivational recoding-free implicit association test (m-IAT-RF)

    DEFF Research Database (Denmark)

    Kraus, Alexandra Anita; Scholderer, Joachim

    2015-01-01

    For the indirect measurement of approach-avoidance tendencies, two procedures are introduced and compared. The procedures are modifications of the standard IAT and the Recoding-Free IAT (IAT-RF) and use a motivational attribute dimension (approach, avoidance) instead of an evaluative one. Study 1...... (N = 162) assesses their convergent and discriminant validity with respect to self-reported measures of motivation and evaluation, and their predictive validity with respect to actual behavior. Study 2 (N = 205) furthermore compares their validity to evaluative variants of the same test paradigms...

  2. Factors associated with frequency of abortions recorded through Dairy Herd Improvement test plans.

    Science.gov (United States)

    Norman, H D; Miller, R H; Wright, J R; Hutchison, J L; Olson, K M

    2012-07-01

    Frequency of abortions recorded through Dairy Herd Improvement (DHI) testing was summarized for cows with lactations completed from 2001 through 2009. For 8.5 million DHI lactations of cows that had recorded breeding dates and were >151 d pregnant at lactation termination, the frequency of recorded abortions was 1.31%. Effects of year, herd-year, month, and pregnancy stage at lactation termination; parity; breed; milk yield; herd size; geographic region; and state within region associated with DHI-recorded abortion were examined. Abortions recorded through DHI (minimum gestation of 152 d required) were more frequent during early gestation; least squares means (LSM) were 4.38, 3.27, 1.19, and 0.59% for 152 to 175, 176 to 200, 201 to 225, and 226 to 250 d pregnant, respectively. Frequency of DHI-recorded abortions was 1.40% for parity 1 and 1.01% for parity ≥ 8. Abortion frequency was highest from May through August (1.42 to 1.53%) and lowest from October through February (1.09 to 1.21%). Frequency of DHI-recorded abortions was higher for Holsteins (1.32%) than for Jerseys (1.10%) and other breeds (1.27%). Little relationship was found between DHI-recorded abortions and herd size. Abortion frequencies for effects should be considered to be underestimated because many abortions, especially those caused by genetic recessives, go undetected. Therefore, various nonreturn rates (NRR; 60, 80, …, 200 d) were calculated to document pregnancy loss confirmed by the absence of homozygotes in the population. Breeding records for April 2011 US Department of Agriculture sire conception rate evaluations were analyzed with the model used for official evaluations with the addition of an interaction between carrier status of the service sire (embryo's sire) and cow sire (embryo's maternal grandsire). Over 13 million matings were examined using various NRR for Holstein lethal recessive traits (brachyspina and complex vertebral malformation) and undesirable recessive haplotypes (HH1

  3. Multiplex polymerase chain reaction tests for detection of pathogens associated with gastroenteritis.

    Science.gov (United States)

    Zhang, Hongwei; Morrison, Scott; Tang, Yi-Wei

    2015-06-01

    A wide range of enteric pathogens can cause infectious gastroenteritis. Conventional diagnostic algorithms are time-consuming and often lack sensitivity and specificity. Advances in molecular technology have provided new clinical diagnostic tools. Multiplex polymerase chain reaction (PCR)-based testing has been used in gastroenterology diagnostics in recent years. This article presents a review of recent laboratory-developed multiplex PCR tests and current commercial multiplex gastrointestinal pathogen tests. It focuses on two commercial syndromic multiplex tests: Luminex xTAG Gastrointestinal Pathogen Panel and BioFire FilmArray gastrointestinal test. Multiplex PCR tests have shown superior sensitivity to conventional methods for detection of most pathogens.

  4. Baseline and verification tests of the electric vehicle associates' current fare station wagon. Final test report, March 27, 1980-November 6, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Dowgiallo, E.J. Jr.; Chapman, R.D.

    1983-01-01

    The EVA Current Fare Wagon was manufactured by Electric Vehicle Associates, Incorporated (EVA) of Cleveland, Ohio. It is now available from Lectra Motors Corp. of Las Vegas, Nevada. The vehicle was tested under the direction of MERADCOM from 27 March 1980 to 6 November 1981. The tests are part of a Department of Energy project to assess advances in electric vehicle design. This report presents the performance test results on the EVA Current Fare Wagon. The EVA Current Fare Wagon is a 1980 Ford Fairmont station wagon which has been converted to an electric vehicle. The propulsion system is made up of a Cableform controller, a series-wound 30-hp Reliance Electric Motor, and 22 6-V lead-acid batteries. The Current Fare Wagon is also equipped with regenerative braking. Further details of the vehicle are given in the Vehicle Summary Data Sheet, Appendix A. The results of this testing are given in Table 1.

  5. Gene-based multiple regression association testing for combined examination of common and low frequency variants in quantitative trait analysis

    Directory of Open Access Journals (Sweden)

    Yun Joo eYoo

    2013-11-01

    Full Text Available Multi-marker methods for genetic association analysis can be performed for common and low frequency SNPs to improve power. Regression models are an intuitive way to formulate multi-marker tests. In previous studies we evaluated regression-based multi-marker tests for common SNPs, and through identification of bins consisting of correlated SNPs, developed a multi-bin linear combination (MLC test that is a compromise between a 1df linear combination test and a multi-df global test. Bins of SNPs in high linkage disequilibrium (LD are identified, and a linear combination of individual SNP statistics is constructed within each bin. Then association with the phenotype is represented by an overall statistic with df as many or few as the number of bins. In this report we evaluate multi-marker tests for SNPs that occur at low frequencies. There are many linear and quadratic multi-marker tests that are suitable for common or low frequency variant analysis. We compared the performance of the MLC tests with various linear and quadratic statistics in joint or marginal regressions. For these comparisons, we performed a simulation study of genotypes and quantitative traits for 85 genes with many low frequency SNPs based on HapMap Phase III. We compared the tests using 1 set of all SNPs in a gene, 2 set of common SNPs in a gene (MAF≥5%, 3 set of low frequency SNPs (1%≤MAF

  6. Cognitive function is associated with risk aversion in community-based older persons

    Directory of Open Access Journals (Sweden)

    Buchman Aron S

    2011-09-01

    Full Text Available Abstract Background Emerging data from younger and middle-aged persons suggest that cognitive ability is negatively associated with risk aversion, but this association has not been studied among older persons who are at high risk of experiencing loss of cognitive function. Methods Using data from 369 community-dwelling older persons without dementia from the Rush Memory and Aging Project, an ongoing longitudinal epidemiologic study of aging, we examined the correlates of risk aversion and tested the hypothesis that cognition is negatively associated with risk aversion. Global cognition and five specific cognitive abilities were measured via detailed cognitive testing, and risk aversion was measured using standard behavioral economics questions in which participants were asked to choose between a certain monetary payment ($15 versus a gamble in which they could gain more than $15 or gain nothing; potential gamble gains ranged from $21.79 to $151.19 with the gain amounts varied randomly over questions. We first examined the bivariate associations of age, education, sex, income and cognition with risk aversion. Next, we examined the associations between cognition and risk aversion via mixed models adjusted for age, sex, education, and income. Finally, we conducted sensitivity analyses to ensure that our results were not driven by persons with preclinical cognitive impairment. Results In bivariate analyses, sex, education, income and global cognition were associated with risk aversion. However, in a mixed effect model, only sex (estimate = -1.49, standard error (SE = 0.39, p i.e., semantic memory, episodic memory, working memory, and perceptual speed; performance on visuospatial abilities was not. Conclusion A lower level of cognitive ability and female sex are associated with greater risk aversion in advanced age.

  7. Association of black race with follow-up of an abnormal prostate-specific antigen test.

    Science.gov (United States)

    Turner, Barbara J; Mavandadi, Shahrzad; Weiner, Mark G

    2011-02-01

    Delayed evaluation after a clearly abnormal prostate-specific antigen (PSA) result may contribute to more advanced prostate cancer at diagnosis in black men. In 46 primary care practices over a period of 4.5 years, we studied men aged more than 50 years without known prostate cancer who had a PSA of at least 10.0 ng/mL for the first time. PSA follow-up included: a urology appointment, a new prostate diagnosis, or repeat PSA test. Cox proportional hazards models assessed time to follow-up, adjusting for demographic, clinical, and health care factors with censoring at a time that represents excessive delay (200 days). Among all 724 study men (27% black), delay until PSA follow-up averaged 115.2 days (+/- 79.7 d) and the unadjusted hazard ratio (HR) for follow-up was shorter for black men than nonblack men (HR, 1.23; 95% CI, 1.00-1.51). However, black men were more likely to have had prior urology care and had higher index PSA levels than other men; both factors were associated with shorter follow-up. After adjustment, delay did not differ for black vs nonblack race (HR, 1.05; 95% Cl, 0.78-1.43) but men aged at least 75 years had a longer delay than men aged 74 years or less (HR, 0.72; 95% CI, 0.59-0.89). Despite black men having greater risk of advanced prostate disease at diagnosis and better linkage to urologic care, follow-up was delayed, on average, by more than 3 months and did not differ by race. These results reveal a potentially important, remediable factor to improve prostate cancer prevention and care for black men.

  8. "Passageless" Administration of the Nelson-Denny Reading Comprehension Test: Associations with IQ and Reading Skills

    Science.gov (United States)

    Ready, Rebecca E.; Chaudhry, Maheen F.; Schatz, Kelly C.; Strazzullo, Sarah

    2013-01-01

    There are few tests that assess reading comprehension in adults, but these tests are needed for a comprehensive assessment of reading disorders (RD). "The Nelson-Denny Reading Test" (NDRT) has a long-passage reading comprehension component that can be used with adolescents and adults. A problem with the NDRT is that reading comprehension…

  9. Is generalized maternal optimism or pessimism during pregnancy associated with unplanned cesarean section deliveries in China?

    Science.gov (United States)

    Moyer, Cheryl A; Elsayed, Yasmin; Zhu, Yuchun; Wei, Yumei; Engmann, Cyril M; Yang, Huixia

    2010-01-01

    This research examines whether maternal optimism/pessimism is associated with unplanned Cesarean section deliveries in China. If so, does the association remain after controlling for clinical factors associated with C-sections? A sample of 227 mostly primiparous women in the third trimester of pregnancy was surveyed in a large tertiary care hospital in Beijing, China. Post-delivery data were collected from medical records. In bivariate analysis, both optimism and pessimism were related to unplanned c-section. However, when optimism and pessimism were entered into a regression model together, optimism was no longer statistically significant. Pessimism remained significant, even when adjusting for clinical factors such as previous abortion, previous miscarriage, pregnancy complications, infant gestational age, infant birthweight, labor duration, birth complications, and self-rated difficulty of the pregnancy. This research suggests that maternal mindset during pregnancy has a role in mode of delivery. However, more research is needed to elucidate potential causal pathways and test potential interventions.

  10. Utility of quantitative sensory testing and screening tools in identifying HIV-associated peripheral neuropathy in Western Kenya: pilot testing.

    Directory of Open Access Journals (Sweden)

    Deanna Cettomai

    Full Text Available BACKGROUND/AIM: Neuropathy is the most common neurologic complication of HIV but is widely under-diagnosed in resource-constrained settings. We aimed to identify tools that accurately distinguish individuals with moderate/severe peripheral neuropathy and can be administered by non-physician healthcare workers (HCW in resource-constrained settings. METHODS: We enrolled a convenience sample of 30 HIV-infected outpatients from a Kenyan HIV-care clinic. A HCW administered the Neuropathy Severity Score (NSS, Single Question Neuropathy Screen (Single-QNS, Subjective Peripheral Neuropathy Screen (Subjective-PNS, and Brief Peripheral Neuropathy Screen (Brief-PNS. Monofilament, graduated tuning fork, and two-point discrimination examinations were performed. Tools were validated against a neurologist's clinical assessment of moderate/severe neuropathy. RESULTS: The sample was 57% male, mean age 38.6 years, and mean CD4 count 324 cells/µL. Neurologist's assessment identified 20% (6/30 with moderate/severe neuropathy. Diagnostic utilities for moderate/severe neuropathy were: Single-QNS--83% sensitivity, 71% specificity; Subjective-PNS-total--83% sensitivity, 83% specificity; Subjective-PNS-max and NSS--67% sensitivity, 92% specificity; Brief-PNS--0% sensitivity, 92% specificity; monofilament--100% sensitivity, 88% specificity; graduated tuning fork--83% sensitivity, 88% specificity; two-point discrimination--75% sensitivity, 58% specificity. CONCLUSIONS: Pilot testing suggests Single-QNS, Subjective-PNS, and monofilament examination accurately identify HIV-infected patients with moderate/severe neuropathy and may be useful diagnostic tools in resource-constrained settings.

  11. Simple Algorithms to Calculate Asymptotic Null Distributions of Robust Tests in Case-Control Genetic Association Studies in R

    Directory of Open Access Journals (Sweden)

    Wing Kam Fung

    2010-02-01

    Full Text Available The case-control study is an important design for testing association between genetic markers and a disease. The Cochran-Armitage trend test (CATT is one of the most commonly used statistics for the analysis of case-control genetic association studies. The asymptotically optimal CATT can be used when the underlying genetic model (mode of inheritance is known. However, for most complex diseases, the underlying genetic models are unknown. Thus, tests robust to genetic model misspecification are preferable to the model-dependant CATT. Two robust tests, MAX3 and the genetic model selection (GMS, were recently proposed. Their asymptotic null distributions are often obtained by Monte-Carlo simulations, because they either have not been fully studied or involve multiple integrations. In this article, we study how components of each robust statistic are correlated, and find a linear dependence among the components. Using this new finding, we propose simple algorithms to calculate asymptotic null distributions for MAX3 and GMS, which greatly reduce the computing intensity. Furthermore, we have developed the R package Rassoc implementing the proposed algorithms to calculate the empirical and asymptotic p values for MAX3 and GMS as well as other commonly used tests in case-control association studies. For illustration, Rassoc is applied to the analysis of case-control data of 17 most significant SNPs reported in four genome-wide association studies.

  12. Factors associated with failure to return for HIV test results in a free and anonymous screening centre.

    Science.gov (United States)

    Laanani, Moussa; Dozol, Adrien; Meyer, Laurence; David, Stéphane; Camara, Sékou; Segouin, Christophe; Troude, Pénélope

    2015-07-01

    Free and anonymous screening centres (CDAG: Centres de Depistage Anononyme et Gratuit) are public facilities set up for HIV infection diagnosis in France. Some people visiting CDAG fail to return for test results and are not informed of their serology. This study aimed to assess factors associated with failure to return for HIV test results. Patients visiting the Fernand-Widal CDAG (Paris) for an HIV test in January-February 2011 were eligible to take part in the study. Data were collected with an anonymous self-administered questionnaire. Factors associated with failure to return were assessed using logistic regression models. Of the 710 participants (participation rate 88%), 46 patients failed to return. Not specifying birthplace and not living in the region of Paris were associated with failure to return. Those who perceived no risk of HIV infection and those who felt they were more at risk than other people were both statistically associated with failure to return. Self-perceived risk seemed to be of chief concern for failure to return for HIV test results and should be considered during pre-test counselling.

  13. Endothelial function and sleep: associations of flow-mediated dilation with perceived sleep quality and rapid eye movement (REM) sleep.

    Science.gov (United States)

    Cooper, Denise C; Ziegler, Michael G; Milic, Milos S; Ancoli-Israel, Sonia; Mills, Paul J; Loredo, José S; Von Känel, Roland; Dimsdale, Joel E

    2014-02-01

    Endothelial function typically precedes clinical manifestations of cardiovascular disease and provides a potential mechanism for the associations observed between cardiovascular disease and sleep quality. This study examined how subjective and objective indicators of sleep quality relate to endothelial function, as measured by brachial artery flow-mediated dilation (FMD). In a clinical research centre, 100 non-shift working adults (mean age: 36 years) completed FMD testing and the Pittsburgh Sleep Quality Index, along with a polysomnography assessment to obtain the following measures: slow wave sleep, percentage rapid eye movement (REM) sleep, REM sleep latency, total arousal index, total sleep time, wake after sleep onset, sleep efficiency and apnea-hypopnea index. Bivariate correlations and follow-up multiple regressions examined how FMD related to subjective (i.e., Pittsburgh Sleep Quality Index scores) and objective (i.e., polysomnography-derived) indicators of sleep quality. After FMD showed bivariate correlations with Pittsburgh Sleep Quality Index scores, percentage REM sleep and REM latency, further examination with separate regression models indicated that these associations remained significant after adjustments for sex, age, race, hypertension, body mass index, apnea-hypopnea index, smoking and income (Ps Quality Index increased (indicating decreased subjective sleep quality) and percentage REM sleep decreased, while REM sleep latency increased (Ps quality and adverse changes in REM sleep were associated with diminished vasodilation, which could link sleep disturbances to cardiovascular disease.

  14. Single test isolated lupus anticoagulant positivity is associated with increased plasma levels of inflammatory markers and dyslipidemia

    DEFF Research Database (Denmark)

    Just, S A; Nybo, M; Laustrup, H

    2016-01-01

    OBJECTIVE: To investigate whether a single positive test for lupus anticoagulant (LA) is associated with levels of inflammatory markers and traditional cardiovascular risk factors, independent of autoimmune disease, thrombophilia and occurrence of other antiphospholipid antibodies. METHODS......: In a retrospective observational study we included persons referred for thrombophilia testing during 2011-2014. Persons with autoimmune disease, thrombophilia or presence of specific anti-phospholipid antibodies were excluded. Multivariate logistic regression analyses adjusted for age and sex was performed and odds...

  15. On Some Transformation and Summation Formulae for Bivariate Basic Hypergeometric Series%双变量基本超几何级数的若干变换与求和公式

    Institute of Scientific and Technical Information of China (English)

    张之正; 胡秋霞

    2009-01-01

    The purpose of this paper is to establish several transformation formulae for bi-variate basic hypergeometric series by means of series rearrangement technique. From these transformations, some interesting summation formulae are obtained.

  16. Application of continuous normal-lognormal bivariate density functions in a sensitivity analysis of municipal solid waste landfill.

    Science.gov (United States)

    Petrovic, Igor; Hip, Ivan; Fredlund, Murray D

    2016-09-01

    The variability of untreated municipal solid waste (MSW) shear strength parameters, namely cohesion and shear friction angle, with respect to waste stability problems, is of primary concern due to the strong heterogeneity of MSW. A large number of municipal solid waste (MSW) shear strength parameters (friction angle and cohesion) were collected from published literature and analyzed. The basic statistical analysis has shown that the central tendency of both shear strength parameters fits reasonably well within the ranges of recommended values proposed by different authors. In addition, it was established that the correlation between shear friction angle and cohesion is not strong but it still remained significant. Through use of a distribution fitting method it was found that the shear friction angle could be adjusted to a normal probability density function while cohesion follows the log-normal density function. The continuous normal-lognormal bivariate density function was therefore selected as an adequate model to ascertain rational boundary values ("confidence interval") for MSW shear strength parameters. It was concluded that a curve with a 70% confidence level generates a "confidence interval" within the reasonable limits. With respect to the decomposition stage of the waste material, three different ranges of appropriate shear strength parameters were indicated. Defined parameters were then used as input parameters for an Alternative Point Estimated Method (APEM) stability analysis on a real case scenario of the Jakusevec landfill. The Jakusevec landfill is the disposal site of the capital of Croatia - Zagreb. The analysis shows that in the case of a dry landfill the most significant factor influencing the safety factor was the shear friction angle of old, decomposed waste material, while in the case of a landfill with significant leachate level the most significant factor influencing the safety factor was the cohesion of old, decomposed waste material. The

  17. The association of asthma, nasal allergies, and positive skin prick tests with obesity, leptin, and adiponectin

    OpenAIRE

    Newson, RB; M. Jones; Forsberg, B; Janson, C; Bossios, A; Dahlen, S-E; Toskala, EM; Al-Kalemji, A; Kowalski, ML; Rymarcsyk, B; Salagean, EM; van Drunen, CM; Bachert, C; Wehrend, T; Krämer, User

    2014-01-01

    Background Cross-sectional and longitudinal reports show that obese adults have more asthma than non-obese adults. A proposed mechanism is via effects of adipokines (leptin and adiponectin) on the immune system. Objective We wished to measure the associations of asthma and other atopic diseases with serum adipokine levels and to find whether the associations with asthma were strong enough to rule out the possibility that they are secondary to the association of fatness measures with ast...

  18. PPARA intron polymorphism associated with power performance in 30-s anaerobic Wingate Test.

    Directory of Open Access Journals (Sweden)

    Miroslav Petr

    Full Text Available To date, polymorphisms in several genes have been associated with a strength/power performance including alpha 3 actinin, ciliary neurotrophic factor, vitamin D receptor, or angiotensin I converting enzyme, underlining the importance of genetic component of the multifactorial strength/power-related phenotypes. The single nucleotide variation in peroxisome proliferator-activated receptor alpha gene (PPARA intron 7 G/C (rs4253778; g.46630634G>C has been repeatedly found to play a significant role in response to different types of physical activity. We investigated the effect of PPARA intron 7 G/C polymorphism specifically on anaerobic power output in a group of 77 elite male Czech ice hockey players (18-36 y. We determined the relative peak power per body weight (Pmax.kg(-1 and relative peak power per fat free mass (W.kg(-1FFM during the 30-second Wingate Test (WT30 on bicycle ergometer (Monark 894E Peak bike, MONARK, Sweden. All WT30s were performed during the hockey season. Overall genotype frequencies were 50.6% GG homozygotes, 40.3% CG heterozygotes, and 9.1% CC homozygotes. We found statistically significant differences in Pmax.kg(-1 and marginally significant differences in Pmax.kg(-1FFM values in WT30 between carriers and non-carriers for C allele (14.6 ± 0.2 vs. 13.9 ± 0.3 W.kg(-1 and 15.8 ± 0.2 vs. 15.2 ± 0.3 W.kg(-1FFM, P = 0.036 and 0.12, respectively. Furthermore, Pmax.kg(-1FFM strongly positively correlated with the body weight only in individuals with GG genotypes (R = 0.55; p<0.001. Our results indicate that PPARA 7C carriers exhibited higher speed strength measures in WT30. We hypothesize that C allele carriers within the cohort of trained individuals may possess a metabolic advantage towards anaerobic metabolism.

  19. Magnitude and variability of effect sizes for the associations between chronic pain and cognitive test performances: a meta-analysis

    Science.gov (United States)

    Rathbone, Michél; Parkinson, William; Rehman, Yasir; Jiang, Shucui; Bhandari, Mohit; Kumbhare, Dinesh

    2016-01-01

    Objectives and Methods: A systematic review and meta-analysis were performed to estimate the size and variability of the association between chronic pain (CP) and poorer cognitive test performances as a function of individual tests, pain sub-types, and study sources on 22 studies having (1) a control group, (2) reported means and standard deviations (SDs) and (3) tests studied at least 3 times. Results: CP patients performed significantly poorer with small to moderate effects (d = −.31 to −.57) on Digit Span Backward; STROOP Word; Color and Color-Word; Digit Symbol; Trail Making A and B; Rey Auditory Learning Immediate and Delayed Recall and Recognition. For these 10 measures, single effects (no interaction) were supported (I2 = 0%–8%) and Random and Fixed models yielded similar results. No group differences were found for Corsi Blocks Forward or Wisconsin Cart Sorting Test Categories Achieved, or Perseveration. Effects for the Rey Complex Figure Immediate and Delayed Recall were significant, but effect size was inconclusive, given moderate to high heterogeneity and lack of consistency between Random and Fixed models. For the Paced Auditory Serial Addition Test, there was a homogeneous (I2 = 0%) and significantly lower performance in fibromyalgia (d = −.47), but no effect in diagnostically undifferentiated pain samples, and wide variability across studies of whiplash (d = −.15 to −1.04, I2 = 60%). Conclusion: The magnitude and consistency of the CP – cognition effect depended on the test, pain subgroup and study source. Summary points Among tests showing a chronic pain (CP) – cognition effect, the magnitude of this association was consistently small to moderate across tests. Effect size estimation was inconclusive for Digit Span Forwards, the Paced Auditory Serial Addition Test and the Rey Complex Figure Test. Variance was too heterogeneous for testing cognitive domain specificity of the CP – cognition effect. PMID:27583141

  20. False-positive rates associated with the use of multiple performance and symptom validity tests.

    Science.gov (United States)

    Larrabee, Glenn J

    2014-06-01

    Performance validity test (PVT) error rates using Monte Carlo simulation reported by Berthelson and colleagues (in False positive diagnosis of malingering due to the use of multiple effort tests. Brain Injury, 27, 909-916, 2013) were compared with PVT and symptom validity test (SVT) failure rates in two nonmalingering clinical samples. At a per-test false-positive rate of 10%, Monte Carlo simulation overestimated error rates for: (i) failure of ≥2 out of 5 PVTs/SVT for Larrabee (in Detection of malingering using atypical performance patterns on standard neuropsychological tests. The Clinical Neuropsychologist, 17, 410-425, 2003) and ACS (Pearson, Advanced clinical solutions for use with WAIS-IV and WMS-IV. San Antonio: Pearson Education, 2009) and (ii) failure of ≥2 out of 7 PVTs/SVT for Larrabee (Detection of malingering using atypical performance patterns on standard neuropsychological tests. The Clinical Neuropsychologist, 17, 410-425, 2003; Malingering scales for the Continuous Recognition Memory Test and Continuous Visual Memory Test. The Clinical Neuropsychologist, 23, 167-180, 2009 combined). Monte Carlo overestimation is likely because PVT performances are atypical in pattern or degree for what occurs in actual neurologic, psychiatric, or developmental disorders. Consequently, PVT scores form skewed distributions with performance at ceiling and restricted range, rather than forming a standard normal distribution with mean of 0 and standard deviation of 1.0. These results support the practice of using ≥2 PVT/SVT failures as representing probable invalid clinical presentation.

  1. Association between preoperative magnetic resonance imaging, pain intensity and quantitative sensory testing in patients awaiting lumbar diskectomy.

    LENUS (Irish Health Repository)

    Hegarty, Dominic

    2011-02-01

    Magnetic resonance imaging (MRI) offers important information regarding the morphology, location and size of a herniated disc, which influences the decision to offer lumbar diskectomy (LD). This study aims to examine the association between clinical neurophysiologic indices including pain intensity and quantitative sensory testing (QST), and the degree of lumbar nerve root compromise depicted on magnetic resonance (MR) in patients awaiting LD.

  2. Comparison of Culture, Cytotoxin Assay and Two Eia Tests with Clinical Diagnosis of Clostridium difficile-Associated Diarrhea

    Directory of Open Access Journals (Sweden)

    Marilyn Binning

    1994-01-01

    Full Text Available Objective: The most common etiology of infectious diarrhea in hospitalized patients is Clostridium difficile. No single laboratory test yields a definitive diagnosis. Four methods were evaluated for their sensitivity and specificity in patients who had clinically defined C difficile-associated diarrhea.

  3. Association between Education and Domestic Violence among Women Being Offered an HIV Test in Urban and Rural Areas in Kenya

    Science.gov (United States)

    Abuya, Benta A.; Onsomu, Elijah O.; Moore, DaKysha; Piper, Crystal N.

    2012-01-01

    The objective of this study was to examine the association between education and domestic violence among women being offered an HIV test in urban and rural areas in Kenya. A sample selection of women who experienced physical (n = 4,308), sexual (n = 4,309), and emotional violence (n = 4,312) aged 15 to 49 allowed for the estimation of the…

  4. Design and testing of the first 2D Prototype Vertically Integrated Pattern Recognition Associative Memory

    Energy Technology Data Exchange (ETDEWEB)

    Liu, T.; Deptuch, G.; Hoff, J.; Jindariani, S.; Joshi, S.; Olsen, J.; Tran, N.; Trimpl, M.

    2015-02-01

    An associative memory-based track finding approach has been proposed for a Level 1 tracking trigger to cope with increasing luminosities at the LHC. The associative memory uses a massively parallel architecture to tackle the intrinsically complex combinatorics of track finding algorithms, thus avoiding the typical power law dependence of execution time on occupancy and solving the pattern recognition in times roughly proportional to the number of hits. This is of crucial importance given the large occupancies typical of hadronic collisions. The design of an associative memory system capable of dealing with the complexity of HL-LHC collisions and with the short latency required by Level 1 triggering poses significant, as yet unsolved, technical challenges. For this reason, an aggressive R&D program has been launched at Fermilab to advance state of-the-art associative memory technology, the so called VIPRAM (Vertically Integrated Pattern Recognition Associative Memory) project. The VIPRAM leverages emerging 3D vertical integration technology to build faster and denser Associative Memory devices. The first step is to implement in conventional VLSI the associative memory building blocks that can be used in 3D stacking, in other words, the building blocks are laid out as if it is a 3D design. In this paper, we report on the first successful implementation of a 2D VIPRAM demonstrator chip (protoVIPRAM00). The results show that these building blocks are ready for 3D stacking.

  5. An implicit test of the associations between children and sex in pedophiles.

    Science.gov (United States)

    Gray, Nicola S; Brown, Anthony S; MacCulloch, Malcolm J; Smith, Jennifer; Snowden, Robert J

    2005-05-01

    Pedophiles are motivated to disguise their thoughts and feelings about their sexual beliefs and attraction toward children. New developments using implicit measures of associations have been successful in accessing socially stigmatic beliefs, even in cases in which the participant is resistant to this disclosure. Using an implicit measure, the authors show that pedophiles have an association between children and sex, whereas nonpedophilic offenders have an association between adults and sex. The task can therefore identify a core cognitive abnormality that may underpin some pedophilic deviant sexual behavior.

  6. Earthquake simulator tests and associated study of an 1/6-scale nine-story RC model

    Institute of Scientific and Technical Information of China (English)

    Sun Jingjiang; Wang Tao; Qi Hu

    2007-01-01

    Earthquake simulator tests of a 1/6-scale nine-story reinforced concrete frame-wall model are described in the paper. The test results and associated numerical simulation are summarized and discussed. Based on the test data,a relationship between maximum inter-story drift and damage state is established. Equations of variation of structural characteristics (natural frequency and equivalent stiffness) with overall drifts are derived by data fitting, which can be used to estimate structural damage state if structural characteristics can be measured. A comparison of the analytical and experimental results show that both the commonly used equivalent beam and fiber element models can simulate the nonlinear seismic response of structures very well. Finally, conclusions associated with seismic design and damage evaluation of RC structures are presented.

  7. EXPLORING SUBSTANCE USE AND HIV TREATMENT FACTORS ASSOCIATED WITH NEUROCOGNITIVE IMPAIRMENT AMONG PEOPLE LIVING WITH HIV/AIDS

    Directory of Open Access Journals (Sweden)

    Jennifer M Attonito

    2014-08-01

    Full Text Available Neurocognitive (NC impairment remains prevalent among people living with HIV (PLWH and may be exacerbated by alcohol and drug use. This cross-sectional study assesses the degree to which alcohol and other drug use, time from HIV diagnosis to treatment, and years living with HIV affect three areas of NC functioning among HIV-seropositive adults. NC functioning in 370 PLWH living in Miami, FL was assessed using the Auditory Verbal Learning Test (AVLT, the Short Category Test, Booklet Format (SCT, and the Color Trails Test 2 (CTT2. Participants reported the number of days using alcohol, marijuana and cocaine over the previous three months, the number of known years living with HIV and length of time from HIV diagnosis to seeking care. Bivariate linear regression and multivariate linear regression were used to test associations between independent and dependent variables. Mean scores on NC measures were significantly lower than published norms; 39% of participants scored >1 standard deviation below normative sample means on >2 NC tests. No significant associations were found between alcohol or cocaine use and any NC measure. Years living with HIV was associated with CTT2 in the bivariate analysis (β=1.031; p=0.007. In multivariate analysis, each day of marijuana use and years living with HIV were associated with a .32 (p=0.05 point and 1.18 (p=0.03 point poorer performance score on the CTT2, respectively. Results suggest that both marijuana use and duration of HIV infection may affect cognitive functioning among PLWH in ways that may impair their ability to follow important treatment guidance.

  8. Applicability of an Indirect VO2max Test: Its Association with the 400 Meters Freestyle Performance

    Directory of Open Access Journals (Sweden)

    Adalberto Veronese da Costa

    Full Text Available Abstract The aim of this study was to evaluate the VO2max using a previously validated indirect test for non-expert adult swimmers and to verify its connection with the 400 meters freestyle test. A total of 17 non-expert male swimmers (21.5 ± 3.12 years were evaluated. Body composition measurements included body weight (74 ± 9.41 kg, height (172.9 ± 5.21 cm and body fat percentage (15.2 ± 4.15 %. Two tests were conducted on different days; the 400 meters freestyle (400 MF and the Progressive Swim Test (PSwT, respectively. The participant's heart rate frequency before and after the test (BHR and AHR was analyzed, as well as the subjective perception of effort (RPE, the number of laps covered (NLP, and the time of test execution measured in minutes. Significant differences were identified in all variables (p - 0.60 was found between AHR and execution time (r > - 0.70, as well as between the VO2max estimated by the PSwT and the 400 MF performance test (r > - 0.70. The Bland-Altman Plot showed that the values discovered were within the established concordance limits of 95% (±1.96 SD. A negative correlation between a swimming test and a test that estimates the VO2max occurred, and the PSwT showed results of greater approximation of the aerobic power of non-expert swimmers. In conclusion, the PSwT is applicable for non-expert adult swimmers.

  9. The association of asthma, nasal allergies, and positive skin prick tests with obesity, leptin, and adiponectin

    DEFF Research Database (Denmark)

    Newson, R. B.; Jones, M.; Forsberg, B.;

    2014-01-01

    BackgroundCross-sectional and longitudinal reports show that obese adults have more asthma than non-obese adults. A proposed mechanism is via effects of adipokines (leptin and adiponectin) on the immune system. ObjectiveWe wished to measure the associations of asthma and other atopic diseases...... with serum adipokine levels and to find whether the associations with asthma were strong enough to rule out the possibility that they are secondary to the association of fatness measures with asthma. MethodsThe Global Asthma and Allergy Network of Excellence (GA(2)LEN) clinical follow-up survey is a clinical...... measures of fatness including body mass index and waist/hip ratio, current asthma, and specific skin prick and IgE sensitisation. We used inverse sampling-probability-weighted rank and regression statistics to measure population associations of disease outcomes with adipokines in males and females...

  10. The frequency of missed test results and associated treatment delays in a highly computerized health system

    OpenAIRE

    2007-01-01

    Abstract Background: Diagnostic errors associated with the failure to follow up on abnormal diagnostic studies ("missed results") are a potential cause of treatment delay and a threat to patient safety. Few data exist concerning the frequency of missed results and associated treatment delays within the Veterans Health Administration (VA). Objective: The primary objective of the current study was to assess the frequency of missed results and resulting treatment delays encountered by primary ca...

  11. No trade-off between learning speed and associative flexibility in bumblebees: a reversal learning test with multiple colonies.

    Directory of Open Access Journals (Sweden)

    Nigel E Raine

    Full Text Available Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals that were fast to learn yellow as a predictor of reward were also quick to reverse this association. Furthermore, overnight memory retention tests suggest that faster learning individuals are also better at retaining previously learned information. There is also an effect of relatedness: colonies whose workers were fast to learn the association between yellow and reward also reversed this association rapidly. These results are inconsistent with a trade-off between learning speed and the reversal of a previously made association. On the contrary, they suggest that differences in learning performance and cognitive (behavioural flexibility could reflect more general differences in colony learning ability. Hence, this study provides additional evidence to support the idea that rapid learning and behavioural flexibility have adaptive value.

  12. The use of bivariate spatial modeling of questionnaire and parasitology data to predict the distribution of Schistosoma haematobium in Coastal Kenya.

    Directory of Open Access Journals (Sweden)

    Hugh J W Sturrock

    Full Text Available BACKGROUND: Questionnaires of reported blood in urine (BIU distributed through the existing school system provide a rapid and reliable method to classify schools according to the prevalence of Schistosoma haematobium, thereby helping in the targeting of schistosomiasis control. However, not all schools return questionnaires and it is unclear whether treatment is warranted in such schools. This study investigates the use of bivariate spatial modelling of available and multiple data sources to predict the prevalence of S. haematobium at every school along the Kenyan coast. METHODOLOGY: Data from a questionnaire survey conducted by the Kenya Ministry of Education in Coast Province in 2009 were combined with available parasitological and environmental data in a Bayesian bivariate spatial model. This modeled the relationship between BIU data and environmental covariates, as well as the relationship between BIU and S. haematobium infection prevalence, to predict S. haematobium infection prevalence at all schools in the study region. Validation procedures were implemented to assess the predictive accuracy of endemicity classification. PRINCIPAL FINDINGS: The prevalence of BIU was negatively correlated with distance to nearest river and there was considerable residual spatial correlation at small (~15 km spatial scales. There was a predictable relationship between the prevalence of reported BIU and S. haematobium infection. The final model exhibited excellent sensitivity (0.94 but moderate specificity (0.69 in identifying low (<10% prevalence schools, and had poor performance in differentiating between moderate and high prevalence schools (sensitivity 0.5, specificity 1. CONCLUSIONS: Schistosomiasis is highly focal and there is a need to target treatment on a school-by-school basis. The use of bivariate spatial modelling can supplement questionnaire data to identify schools requiring mass treatment, but is unable to distinguish between moderate and high

  13. The association of general practitioners’ risk attitudes, level of empathy and burnout status with PSA testing

    DEFF Research Database (Denmark)

    Pedersen, Anette Fischer; Carlsen, Anders Helles; Vedsted, Peter

    2015-01-01

    Når alment praktiserende læger sammenlignes, finder man ofte stor variation i raten af PSA-tests foretaget på mandlige patienter. Dette studie viser, at lægens risikovillighed influerer på raten af PSA-tests. Således har patienter, som er registreret hos en læge, som har mange bekymringer for fej...

  14. Factors associated with completion of bowel cancer screening and the potential effects of simplifying the screening test algorithm

    Science.gov (United States)

    Kearns, Benjamin; Whyte, Sophie; Seaman, Helen E; Snowball, Julia; Halloran, Stephen P; Butler, Piers; Patnick, Julietta; Nickerson, Claire; Chilcott, Jim

    2016-01-01

    Background: The primary colorectal cancer screening test in England is a guaiac faecal occult blood test (gFOBt). The NHS Bowel Cancer Screening Programme (BCSP) interprets tests on six samples on up to three test kits to determine a definitive positive or negative result. However, the test algorithm fails to achieve a definitive result for a significant number of participants because they do not comply with the programme requirements. This study identifies factors associated with failed compliance and modifications to the screening algorithm that will improve the clinical effectiveness of the screening programme. Methods: The BCSP Southern Hub data for screening episodes started in 2006–2012 were analysed for participants aged 60–69 years. The variables included age, sex, level of deprivation, gFOBt results and clinical outcome. Results: The data set included 1 409 335 screening episodes; 95.08% of participants had a definitively normal result on kit 1 (no positive spots). Among participants asked to complete a second or third gFOBt, 5.10% and 4.65%, respectively, failed to return a valid kit. Among participants referred for follow up, 13.80% did not comply. Older age was associated with compliance at repeat testing, but non-compliance at follow up. Increasing levels of deprivation were associated with non-compliance at repeat testing and follow up. Modelling a reduction in the threshold for immediate referral led to a small increase in completion of the screening pathway. Conclusions: Reducing the number of positive spots required on the first gFOBt kit for referral for follow-up and targeted measures to improve compliance with follow-up may improve completion of the screening pathway. PMID:26766733

  15. Haplotype association analyses in resources of mixed structure using Monte Carlo testing

    Directory of Open Access Journals (Sweden)

    Thomas Alun

    2010-12-01

    Full Text Available Abstract Background Genomewide association studies have resulted in a great many genomic regions that are likely to harbor disease genes. Thorough interrogation of these specific regions is the logical next step, including regional haplotype studies to identify risk haplotypes upon which the underlying critical variants lie. Pedigrees ascertained for disease can be powerful for genetic analysis due to the cases being enriched for genetic disease. Here we present a Monte Carlo based method to perform haplotype association analysis. Our method, hapMC, allows for the analysis of full-length and sub-haplotypes, including imputation of missing data, in resources of nuclear families, general pedigrees, case-control data or mixtures thereof. Both traditional association statistics and transmission/disequilibrium statistics can be performed. The method includes a phasing algorithm that can be used in large pedigrees and optional use of pseudocontrols. Results Our new phasing algorithm substantially outperformed the standard expectation-maximization algorithm that is ignorant of pedigree structure, and hence is preferable for resources that include pedigree structure. Through simulation we show that our Monte Carlo procedure maintains the correct type 1 error rates for all resource types. Power comparisons suggest that transmission-disequilibrium statistics are superior for performing association in resources of only nuclear families. For mixed structure resources, however, the newly implemented pseudocontrol approach appears to be the best choice. Results also indicated the value of large high-risk pedigrees for association analysis, which, in the simulations considered, were comparable in power to case-control resources of the same sample size. Conclusions We propose hapMC as a valuable new tool to perform haplotype association analyses, particularly for resources of mixed structure. The availability of meta-association and haplotype-mining modules in

  16. IHH gene polymorphism among three horse breeds and its application for association test in horses with osteochondrosis.

    Science.gov (United States)

    Zabek, T; Golonka, P; Fornal, A; Semik, E

    2013-06-01

    Genetic polymorphism of IHH gene were investigated in Angloarabian, Polish Coldblood and Polish Halfbred horses with the inclusion of a group of Polish Halfbreds affected by osteochondrosis. IHH is a good candidate gene for association study of developmental disorders mainly affecting skeleton development. DNA sequence spanning IHH gene annotated in the horse genome and its putative promoter were investigated using SANGER sequencing. Analysis of genetic variability at polymorphic sites in the IHH gene body and the promoter region confirmed genetic differences between warmblood and coldblood horse breeds. A test for allelic and genotypic association at particular SNP sites revealed no association with osteochondrosis in investigated group of Polish Halfbreds. It was concluded that participation of different warmblood breeds in pedigrees of Polish Halfbreds make it difficult to search for genetic variants being associated with this complex disorder in this breed. IHH gene polymorphism investigated among three different horse populations would be valuable for further studies on equine bone developmental disorders.

  17. Electrophysiological correlates of the autobiographical Implicit Association Test (aIAT: response conflict and conflict resolution.

    Directory of Open Access Journals (Sweden)

    Maddalena Marini

    2016-08-01

    Full Text Available The autobiographical IAT (aIAT is an implicit behavioral instrument that can detect autobiographical memories encoded in an individual’s mind by measuring how quickly this person can categorize and associate sentences related to a specific event with the logical dimensions true and false. Faster categorization when an event (e.g., I went to Paris is associated with the dimension true than false indicates that that specific event is encoded as true in the individual’s mind. The aim of this study is to investigate the electrophysiological correlates of the aIAT, used as a memory-detection technique (i.e., to identify which of two events is true. To this end, we recorded ERPs while participants performed an aIAT assessing which of two playing cards they had previously selected. We found an increased N200 and a decreased LPC (or P300 at the fronto-central sites when participants associated the selected playing card with the dimension false than true. Notably, both components have been previously and consistently reported in studies investigating deception. These results suggest that associating a true autobiographical event with the concept of false may involve the same cognitive processes associated with deception.

  18. An improved predictive association rule based classifier using gain ratio and T-test for health care data diagnosis

    Indian Academy of Sciences (India)

    M Nandhini; S N Sivanandam

    2015-09-01

    Health care data diagnosis is a significant task that needs to be executed precisely, which requires much experience and domain-knowledge. Traditional symptoms-based disease diagnosis may perhaps lead to false presumptions. In recent times, Associative Classification (AC), the combination of association rule mining and classification has received attention in health care applications which desires maximum accuracy. Though several AC techniques exist, they lack in generating quality rules for building efficient associative classifier. This paper aims to enhance the accuracy of the existing CPAR (Classification based on Predictive Association Rule) algorithm by generating quality rules using Gain Ratio. Mostly, health care applications deal with high dimensional datasets. Existence of high dimensions causes unfair estimates in disease diagnosis. Dimensionality reduction is commonly applied as a preprocessing step before classification task to improve classifier accuracy. It eliminates redundant and insignificant dimensions by keeping good ones without information loss. In this work, dimensionality reductions by T-test and reduct sets (or simply reducts) are performed as preprocessing step before CPAR and CPAR using Gain Ratio (CPAR-GR) algorithms. An investigation was also performed to determine the impact of T-test and reducts on CPAR and CPAR-GR. This paper synthesizes the existing work carried out in AC, and also discusses the factors that influence the performance of CPAR and CPAR-GR. Experiments were conducted using six health care datasets from UCI machine learning repository. Based on the experiments, CPAR-GR with T-test yields better classification accuracy than CPAR.

  19. Cognitive capacity: no association with recovery of sensibility by Semmes Weinstein test score after peripheral nerve injury of the forearm.

    Science.gov (United States)

    Boender, Z J; Ultee, J; Hovius, S E R

    2010-02-01

    In the recovery process of sensibility after repair of a peripheral nerve injury of the forearm, not only age but also surgical repair techniques are of importance. If regenerating axons are misdirected, reorganisation or other adaptic processes are needed at the level of the somatosensory brain cortex. These processes are thought to be dependent on the patient's cognitive capacity. We conducted a prospective multicentre study to assess the association between cognitive capacity and recovery of sensibility after peripheral nerve damage of the forearm. Patients with a traumatic peripheral nerve lesion of the forearm and consecutive surgical repair were included. After 12 months, the patients were assessed with respect to recovery of sensibility (Semmes-Weinstein monofilaments) and cognitive capacity, with four tests assessing different aspects of cognitive functioning. Twenty-eight patients (25 male, three female; median age: 28.5 years; range: 15-79 years) with median and/or ulnar nerve injury of the forearm were included in the study. Younger age showed a positive association with sensory recovery (beta =-0.845, 95% CI: -1.456 to -0.233; p=0.01). No association was found between the cognitive-capacity tests used and sensory recovery. The present prospective study did not reveal any association between recovery of sensibility measured by Semmes-Weinstein test score and cognitive capacity. Further studies should be performed to confirm these results.

  20. Baseline and verification tests of the Electric Vehicle Associates' Current Fare Station Wagon. Final test report, 27 March 1980-6 November 1981

    Energy Technology Data Exchange (ETDEWEB)

    Dowgiallo, E.J. Jr; Chapman, R.D.

    1983-01-01

    The EVA Current Fare Station Wagon, an electric vehicle, was tested at MERADCOM as part of a Department of Energy project to characterize the state-of-the-art of electric vehicles. The current Fare Wagon was manufactured in Cleveland, Ohio by Electric Vehicle Associates' Incorporated. It is powered by 22 6-V lead-acid batteries driving a 30-hp d.c. series motor through an SCR controller. The motor drives the rear wheels through a manually operated 4-speed transmission. Regenerative braking was provided.

  1. Integrated experimental test program on waterhammer pressure pulses and associated structural responses within a feedwater sparger

    Energy Technology Data Exchange (ETDEWEB)

    Nurkkala, P.; Hoikkanen, J. [Imatran Voima Oy, Vantaa (Finland)

    1997-12-31

    This paper describes the methods and systems as utilized in an integrated experimental thermohydraulic/mechanics analysis test program on waterhammer pressure pulses within a revised feedwater sparger of a Loviisa generation VVER-440-type reactor. This program was carried out in two stages: (1) measurements with a strictly limited set of operating parameters at Loviisa NPP, and (2) measurements with the full set of operating parameters on a test article simulating the revised feedwater sparger. The experiments at Loviisa NPS served as an invaluable source of information on the nature of waterhammer pressure pulses and structural responses. These tests thus helped to set the objectives and formulate the concept for series of tests on a test article to study the water hammer phenomena. The heavily instrumented full size test article of a steam generator feedwater sparger was placed within a pressure vessel simulating the steam generator. The feedwater sparger was subjected to the full range of operating parameters which were to result in waterhammer pressure pulse trains of various magnitudes and duration. Two different designs of revised feedwater sparger were investigated (i.e. `grounded` and `with goose neck`). The following objects were to be met within this program: (1) establish the thermohydraulic parameters that facilitate the occurrence of water hammer pressure pulses, (2) provide a database for further analysis of the pressure pulse phenomena, (3) establish location and severity of these water hammer pressure pulses, (4) establish the structural response due to these pressure pulses, (5) provide input data for structural integrity analysis. (orig.). 3 refs.

  2. Predicting the occurrence of mixed mode failure associated with hydraulic fracturing, part 2 water saturated tests

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Stephen J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broome, Scott Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Choens, Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barrow, Perry Carl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-14

    Seven water-saturated triaxial extension experiments were conducted on four sedimentary rocks. This experimental condition was hypothesized more representative of that existing for downhole hydrofracture and thus it may improve our understanding of the phenomena. In all tests the pore pressure was 10 MPa and confirming pressure was adjusted to achieve tensile and transitional failure mode conditions. Using previous work in this LDRD for comparison, the law of effective stress is demonstrated in extension using this sample geometry. In three of the four lithologies, no apparent chemo-mechanical effect of water is apparent, and in the fourth lithology test results indicate some chemo-mechanical effect of water.

  3. Genetic testing for TMEM154 mutations associated with lentivirus susceptibility in sheep

    Science.gov (United States)

    Ovine lentiviruses cause incurable, progressive, lymphoproliferative diseases that affect millions of sheep worldwide. Genetic variation in the ovine transmembrane protein 154 gene (TMEM154) has been recently associated with lentivirus infections in U.S. sheep. Sheep with the two most common TMEM1...

  4. Testing the association between psychosocial job strain and adverse birth outcomes--design and methods

    DEFF Research Database (Denmark)

    Larsen, Ann D; Hannerz, Harald; Obel, Carsten;

    2011-01-01

    A number of studies have examined the effects of prenatal exposure to stress on birth outcomes but few have specifically focused on psychosocial job strain. In the present protocol, we aim to examine if work characterised by high demands and low control, during pregnancy, is associated...... with the risk of giving birth to a child born preterm or small for gestational age....

  5. Laboratory test differences associated with HTLV-I and HTLV-II infection

    NARCIS (Netherlands)

    Murphy, EL; Glynn, S; Watanabe, K; Fridey, J; Sacher, R; Schreiber, G; Luban, N

    1998-01-01

    Reports of laboratory abnormalities associated with HTLV-I and HTLV-II infection are inconsistent. We assessed complete blood counts and selected serum chemistry measures at enrollment in a cohort of 153 HTLV-I-seropositive, 386 HTLV-II-seropositive, and 795 HTLV-seronegative blood donors. Linear an

  6. Family Friendly Libraries vs. the American Library Association: A Test of Democracy.

    Science.gov (United States)

    Schweinsburg, Jane D.

    1997-01-01

    To protect children from material it considers harmful, Family Friendly Libraries (FFL) seeks to limit access to information in public libraries. This article describes the conflict between the FFL and the American Library Association (ALA). Provides an overview of censorship and U.S. legislative history, presents the FFL position and the ALA…

  7. FARVATX: Family-Based Rare Variant Association Test for X-Linked Genes.

    Science.gov (United States)

    Choi, Sungkyoung; Lee, Sungyoung; Qiao, Dandi; Hardin, Megan; Cho, Michael H; Silverman, Edwin K; Park, Taesung; Won, Sungho

    2016-09-01

    Although the X chromosome has many genes that are functionally related to human diseases, the complicated biological properties of the X chromosome have prevented efficient genetic association analyses, and only a few significantly associated X-linked variants have been reported for complex traits. For instance, dosage compensation of X-linked genes is often achieved via the inactivation of one allele in each X-linked variant in females; however, some X-linked variants can escape this X chromosome inactivation. Efficient genetic analyses cannot be conducted without prior knowledge about the gene expression process of X-linked variants, and misspecified information can lead to power loss. In this report, we propose new statistical methods for rare X-linked variant genetic association analysis of dichotomous phenotypes with family-based samples. The proposed methods are computationally efficient and can complete X-linked analyses within a few hours. Simulation studies demonstrate the statistical efficiency of the proposed methods, which were then applied to rare-variant association analysis of the X chromosome in chronic obstructive pulmonary disease. Some promising significant X-linked genes were identified, illustrating the practical importance of the proposed methods.

  8. Testing Alternative Explanations for the Associations between Parenting and Adolescent Suicidal Problems

    Science.gov (United States)

    Boeninger, Daria K.; Masyn, Katherine E.; Conger, Rand D.

    2013-01-01

    Although studies have established associations between parenting characteristics and adolescent suicidality, the strength of the evidence for these links remains unclear, largely because of methodological limitations, including lack of accounting for possible child effects on parenting. This study addresses these issues by using autoregressive…

  9. PedGenie: an analysis approach for genetic association testing in extended pedigrees and genealogies of arbitrary size

    Directory of Open Access Journals (Sweden)

    Camp Nicola J

    2006-04-01

    Full Text Available Abstract Background We present a general approach to perform association analyses in pedigrees of arbitrary size and structure, which also allows for a mixture of pedigree members and independent individuals to be analyzed together, to test genetic markers and qualitative or quantitative traits. Our software, PedGenie, uses Monte Carlo significance testing to provide a valid test for related individuals that can be applied to any test statistic, including transmission disequilibrium statistics. Single locus at a time, composite genotype tests, and haplotype analyses may all be performed. We illustrate the validity and functionality of PedGenie using simulated and real data sets. For the real data set, we evaluated the role of two tagging-single nucleotide polymorphisms (tSNPs in the DNA repair gene, NBS1, and their association with female breast cancer in 462 cases and 572 controls selected to be BRCA1/2 mutation negative from 139 high-risk Utah breast cancer families. Results The results from PedGenie were shown to be valid both for accurate p-value calculations and consideration of pedigree structure in the simulated data set. A nominally significant association with breast cancer was observed with the NBS1 tSNP rs709816 for carriage of the rare allele (OR = 1.61, 95% CI = 1.10–2.35, p = 0.019. Conclusion PedGenie is a flexible and valid statistical tool that is intuitively simple to understand, makes efficient use of all the data available from pedigrees without requiring trimming, and is flexible to the types of tests to which it can be applied. Further, our analyses of real data indicate NBS1 may play a role in the genetic etiology of heritable breast cancer.

  10. Functional Performance and Associations between Performance Tests and Neurological Assessment Differ in Men and Women with Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Kadri Medijainen

    2015-01-01

    Full Text Available Background. Neurological assessment of a patient with Parkinson’s disease (PD is expected to reflect upon functional performance. As women are known to report more limitations even for same observed functional performance level, present study was designed to examine whether associations between neurological assessments and functional performance differ across genders. Methods. 14 men and 14 women with PD participated. Functional performance was assessed by measuring walking speeds on 10-meter walk test (10MWT and by performing timed-up-and-go-test (TUG. Neurological assessment included Hoehn and Yahr Scale (HY, Movement Disorders Society Unified Parkinson’s Disease Rating Scale (MDS-UPDRS, Schwab and England Activities of Daily Living Scale (S-E, and Mini Mental State Examination (MMSE. Results. In women with PD, Kendall’s tau-b correlation analyses revealed significant correlations between functional performance tests and neurological assessment measures, with the exception in MMSE. No corresponding associations were found for men, although they demonstrated better functional performance, as expected. Conclusion. Men in similar clinical stage of the PD perform better on functional tests than women. Disease severity reflects upon functional performance differently in men and women with PD. Results indicate that when interpreting the assessment results of both functional performance and neurological assessment tests, the gender of the patient should be taken into consideration.

  11. A Test-Retest Reliability Study of the Whiplash Disability Questionnaire in Patients With Acute Whiplash-Associated Disorders

    DEFF Research Database (Denmark)

    Stupar, Maja; Côté, Pierre; Beaton, Dorcas E;

    2015-01-01

    OBJECTIVE: The purpose of this study was to determine the test-retest reliability and the Minimal Detectable Change (MDC) of the Whiplash Disability Questionnaire (WDQ) in individuals with acute whiplash-associated disorders (WADs). METHODS: We performed a test-retest reliability study. We included...... insurance claimants from Ontario who were at least 18years of age, within 21days of their motor vehicle collision and diagnosed as having acute WAD grades I to III. The WDQ, a 13-item questionnaire scored from 0 (no disability) to 130 (complete disability), was administered to all participants at baseline...

  12. Studying Co-evolution of Production and Test Code Using Association Rule Mining

    NARCIS (Netherlands)

    Lubsen, Z.; Zaidman, A.; Pinzger, M.

    2009-01-01

    Long version of the short paper accepted for publication in the proceedings of the 6th International Working Conference on Mining Software Repositories (MSR 2009). Unit tests are generally acknowledged as an important aid to produce high quality code, as they provide quick feedback to developers on

  13. Adaptive combination of P-values for family-based association testing with sequence data.

    Science.gov (United States)

    Lin, Wan-Yu

    2014-01-01

    Family-based study design will play a key role in identifying rare causal variants, because rare causal variants can be enriched in families with multiple affected subjects. Furthermore, different from population-based studies, family studies are robust to bias induced by population substructure. It is well known that rare causal variants are difficult to detect from single-locus tests. Therefore, burden tests and non-burden tests have been developed, by combining signals of multiple variants in a chromosomal region or a functional unit. This inevitably incorporates some neutral variants into the test statistics, which can dilute the power of statistical methods. To guard against the noise caused by neutral variants, we here propose an 'adaptive combination of P-values method' (abbreviated as 'ADA'). This method combines per-site P-values of variants that are more likely to be causal. Variants with large P-values (which are more likely to be neutral variants) are discarded from the combined statistic. In addition to performing extensive simulation studies, we applied these tests to the Genetic Analysis Workshop 17 data sets, where real sequence data were generated according to the 1000 Genomes Project. Compared with some existing methods, ADA is more robust to the inclusion of neutral variants. This is a merit especially when dichotomous traits are analyzed. However, there are some limitations for ADA. First, it is more computationally intensive. Second, pedigree structures and founders' sequence data are required for the permutation procedure. Third, unrelated controls cannot be included. We here show that, for family-based studies, the application of ADA is limited to dichotomous trait analyses with full pedigree information.

  14. Adaptive combination of P-values for family-based association testing with sequence data.

    Directory of Open Access Journals (Sweden)

    Wan-Yu Lin

    Full Text Available Family-based study design will play a key role in identifying rare causal variants, because rare causal variants can be enriched in families with multiple affected subjects. Furthermore, different from population-based studies, family studies are robust to bias induced by population substructure. It is well known that rare causal variants are difficult to detect from single-locus tests. Therefore, burden tests and non-burden tests have been developed, by combining signals of multiple variants in a chromosomal region or a functional unit. This inevitably incorporates some neutral variants into the test statistics, which can dilute the power of statistical methods. To guard against the noise caused by neutral variants, we here propose an 'adaptive combination of P-values method' (abbreviated as 'ADA'. This method combines per-site P-values of variants that are more likely to be causal. Variants with large P-values (which are more likely to be neutral variants are discarded from the combined statistic. In addition to performing extensive simulation studies, we applied these tests to the Genetic Analysis Workshop 17 data sets, where real sequence data were generated according to the 1000 Genomes Project. Compared with some existing methods, ADA is more robust to the inclusion of neutral variants. This is a merit especially when dichotomous traits are analyzed. However, there are some limitations for ADA. First, it is more computationally intensive. Second, pedigree structures and founders' sequence data are required for the permutation procedure. Third, unrelated controls cannot be included. We here show that, for family-based studies, the application of ADA is limited to dichotomous trait analyses with full pedigree information.

  15. Joint inversion of hydraulic head and self-potential data associated with harmonic pumping tests

    Science.gov (United States)

    Soueid Ahmed, A.; Jardani, A.; Revil, A.; Dupont, J. P.

    2016-09-01

    Harmonic pumping tests consist in stimulating an aquifer by the means of hydraulic stimulations at some discrete frequencies. The inverse problem consisting in retrieving the hydraulic properties is inherently ill posed and is usually underdetermined when considering the number of well head data available in field conditions. To better constrain this inverse problem, we add self-potential data recorded at the ground surface to the head data. The self-potential method is a passive geophysical method. Its signals are generated by the groundwater flow through an electrokinetic coupling. We showed using a 3-D saturated unconfined synthetic aquifer that the self-potential method significantly improves the results of the harmonic hydraulic tomography. The hydroelectric forward problem is obtained by solving first the Richards equation, describing the groundwater flow, and then using the result in an electrical Poisson equation describing the self-potential problem. The joint inversion problem is solved using a reduction model based on the principal component geostatistical approach. In this method, the large prior covariance matrix is truncated and replaced by its low-rank approximation, allowing thus for notable computational time and storage savings. Three test cases are studied, to assess the validity of our approach. In the first test, we show that when the number of harmonic stimulations is low, combining the harmonic hydraulic and self-potential data does not improve the inversion results. In the second test where enough harmonic stimulations are performed, a significant improvement of the hydraulic parameters is observed. In the last synthetic test, we show that the electrical conductivity field required to invert the self-potential data can be determined with enough accuracy using an electrical resistivity tomography survey using the same electrodes configuration as used for the self-potential investigation.

  16. A Hybrid Forecasting Model Based on Bivariate Division and a Backpropagation Artificial Neural Network Optimized by Chaos Particle Swarm Optimization for Day-Ahead Electricity Price

    Directory of Open Access Journals (Sweden)

    Zhilong Wang

    2014-01-01

    Full Text Available In the electricity market, the electricity price plays an inevitable role. Nevertheless, accurate price forecasting, a vital factor affecting both government regulatory agencies and public power companies, remains a huge challenge and a critical problem. Determining how to address the accurate forecasting problem becomes an even more significant task in an era in which electricity is increasingly important. Based on the chaos particle swarm optimization (CPSO, the backpropagation artificial neural network (BPANN, and the idea of bivariate division, this paper proposes a bivariate division BPANN (BD-BPANN method and the CPSO-BD-BPANN method for forecasting electricity price. The former method creatively transforms the electricity demand and price to be a new variable, named DV, which is calculated using the division principle, to forecast the day-ahead electricity by multiplying the forecasted values of the DVs and forecasted values of the demand. Next, to improve the accuracy of BD-BPANN, chaos particle swarm optimization and BD-BPANN are synthesized to form a novel model, CPSO-BD-BPANN. In this study, CPSO is utilized to optimize the initial parameters of BD-BPANN to make its output more stable than the original model. Finally, two forecasting strategies are proposed regarding different situations.

  17. Clinimetric Testing in Mexican Elders: Associations with Age, Gender, and Place of Residence

    Science.gov (United States)

    Tavano-Colaizzi, Lorena; Arroyo, Pedro; Loria, Alvar; Pérez-Lizaur, Ana Bertha; Pérez-Zepeda, Mario Ulises

    2014-01-01

    Aim: To evaluate the ability of five clinimetric instruments to discriminate between subjects >60 years of age living at home versus those living in a residency. Methods: Trained nutritionists applied five instruments (cognition/depression/functionality/nutrition/appetite) to 285 subjects with majorities of women (64%), aged <80 years (61%), and home residents (54%). Results: Multivariable regression models were generated for each instrument using age, gender, and residency as independent variables. Age was associated with worsening scores in the five instruments whereas residency showed association in three instruments, and gender in two. Score-age regressions by place of residency showed differences suggesting that Mundet residents had increasingly worse scores with increasing age than home dwellers for cognition, depression, and nutrition. Also, living at home prevented the worsening of depression with increasing age. In contrast, functionality and appetite deteriorated at a similar rate for home and Mundet residents suggesting an inability of these two instruments to discriminate between settings. Score-age regressions by gender suggested that males have less cognitive problems at 60 and 80 years of age but not at 100 years, and better appetite than women at all ages. Conclusion: Increasing age proved to be associated to worsening scores in the five instruments but only three were able to detect differences according to setting. An interesting observation was that living at home appeared to prevent the depression increase with increasing age seen in Mundet residents. PMID:25593910

  18. Clinimetric testing in Mexican elders: associations with age, gender and place of residence

    Directory of Open Access Journals (Sweden)

    Lorena eTavano-Colaizzi

    2014-10-01

    Full Text Available Aim. To evaluate the ability of five clinimetric instruments to discriminate between subjects >60 years of age living at home versus those living in a residency.Methods. Trained nutritionists applied five instruments (Cognition/ Depression/ Functionality/ Nutrition/ Appetite to 285 subjects with majorities of women (64%, aged <80y (61% and home residents (54%.Results. Multivariable regression models were generated for each instrument using age, gender and residency as independent variables. Age was associated with worsening scores in the five instruments whereas residency showed association in three instruments, and gender in two. Score-age regressions by place of residency showed differences suggesting that Mundet residents had increasingly worse scores with increasing age, than home dwellers for Cognition, Depression and Nutrition. Also, living at home prevented the worsening of Depression with increasing age. In contrast, Functionality and Appetite deteriorated at a similar rate for home and Mundet residents suggesting an inhability of these two instruments to dicriminate between settings. Score-age regressions by gender suggested males have less cognitive problems at 60 and 80 years of age but not at 100, and better appetite than women at all ages.Conclusions. Increasing age proved to be associated to worsening scores in the five instruments but only three were able to detect differences according to setting. An interesting observation was that living at home appeared to prevent the Depression increase with increasing age seen in Mundet residents.

  19. The effect of Trier Social Stress Test (TSST) on item and associative recognition of words and pictures in healthy participants

    OpenAIRE

    Jonathan eGuez; Rotem eSaar-Ashkenazy; Eldad eKeha; Chen eTiferet

    2016-01-01

    Psychological stress, induced by the Trier Social Stress Test (TSST), has repeatedly been shown to alter memory performance. Although factors influencing memory performance such as stimulus nature (verbal /pictorial) and emotional valence have been extensively studied, results whether stress impairs or improves memory are still inconsistent. This study aimed at exploring the effect of TSST on item versus associative memory for neutral, verbal, and pictorial stimuli. 48 healthy subjects were r...

  20. Heterogeneity in glucose response curves during an oral glucose tolerance test and associated cardiometabolic risk

    DEFF Research Database (Denmark)

    Hulman, Adam; Simmons, Rebecca Kate; Vistisen, Dorte;

    2017-01-01

    patterns of plasma glucose change during the oral glucose tolerance test. Cardiometabolic risk factor profiles were compared between the identified groups. Using latent class trajectory analysis, five glucose response curves were identified. Despite similar fasting and 2-h values, glucose peaks and peak...... in Denmark, the Netherlands and the USA. Each study included between 5 and 11 measurements at different time points during a 2-h oral glucose tolerance test, resulting in 9,602 plasma glucose measurements. Latent class trajectories with a cubic specification for time were fitted to identify different...... times varied greatly between groups, ranging from 7–12 mmol/L, and 35–70 min. The group with the lowest and earliest plasma glucose peak had the lowest estimated cardiovascular risk, while the group with the most delayed plasma glucose peak and the highest 2-h value had the highest estimated risk. One...

  1. Routine disc diffusion antimicrobial susceptibility testing of Clostridium difficile and association with PCR ribotype 027

    DEFF Research Database (Denmark)

    Holt, H M; Danielsen, T K; Justesen, U S

    2015-01-01

    Reduced susceptibility to metronidazole and vancomycin in Clostridium difficile has been reported, which emphasises the need for simple antimicrobial susceptibility testing methods. The aim of this study was to apply a published disc diffusion method and zone diameter breakpoint correlates...... the published breakpoint (difficile PCR ribotype 027 isolates had smaller zone...... diameters than non-027 isolates. The disc diffusion method is very simple and inexpensive, and the published zone diameter breakpoints will detect C. difficile isolates with reduced susceptibility to metronidazole and vancomycin....

  2. Does knowledge make a difference? The association between knowledge about genes and attitudes toward gene tests

    DEFF Research Database (Denmark)

    Jallinoja, P; Aro, A R

    2000-01-01

    and understand information about genetics and specific diseases when faced with a need for it. Second, steps should be taken to provide citizens with tools to perceive and discuss potential ethical and social problems, which development of gene technology, genetic testing, and screening bring along. Sites...... for these enterprises could be the biology school curriculum, genetic counseling, media, as well as health education and health communication in general....

  3. Association of hip pain with radiographic evidence of hip osteoarthritis: diagnostic test study

    OpenAIRE

    Kim, Chan; Nevitt, Michael C.; Niu, Jingbo; Clancy, Mary M; Nancy E Lane; Link, Thomas M.; Vlad, Steven; Tolstykh, Irina; Jungmann, Pia M.; Felson, David T.; Guermazi, Ali

    2015-01-01

    Study question Is there concordance between hip pain and radiographic hip osteoarthritis? Methods In this diagnostic test study, pelvic radiographs were assessed for hip osteoarthritis in two cohorts: the Framingham Osteoarthritis Study (community of Framingham, Massachusetts) and the Osteoarthritis Initiative (a multicenter longitudinal cohort study of osteoarthritis in the United States). Using visual representation of the hip joint, participants reported whether they had hip pain on most d...

  4. Statistical testing of the association between annual turnover and marketing activities in SMEs using χ2

    Science.gov (United States)

    Pater, Liana; Miclea, Şerban; Izvercian, Monica

    2016-06-01

    This paper considers the impact of SMEs' annual turnover upon its marketing activities (in terms of marketing responsibility, strategic planning and budgeting). Empirical results and literature reviews unveil that SMEs managers incline to partake in planned and profitable marketing activities, depending on their turnover's level. Thus, using the collected data form 131 Romanian SMEs managers, we have applied the Chi-Square Test in order to validate or invalidate three research assumptions (hypotheses), created starting from the empirical and literature findings.

  5. Testing Rare-Variant Association without Calling Genotypes Allows for Systematic Differences in Sequencing between Cases and Controls.

    Directory of Open Access Journals (Sweden)

    Yi-Juan Hu

    2016-05-01

    Full Text Available Next-generation sequencing of DNA provides an unprecedented opportunity to discover rare genetic variants associated with complex diseases and traits. However, the common practice of first calling underlying genotypes and then treating the called values as known is prone to false positive findings, especially when genotyping errors are systematically different between cases and controls. This happens whenever cases and controls are sequenced at different depths, on different platforms, or in different batches. In this article, we provide a likelihood-based approach to testing rare variant associations that directly models sequencing reads without calling genotypes. We consider the (weighted burden test statistic, which is the (weighted sum of the score statistic for assessing effects of individual variants on the trait of interest. Because variant locations are unknown, we develop a simple, computationally efficient screening algorithm to estimate the loci that are variants. Because our burden statistic may not have mean zero after screening, we develop a novel bootstrap procedure for assessing the significance of the burden statistic. We demonstrate through extensive simulation studies that the proposed tests are robust to a wide range of differential sequencing qualities between cases and controls, and are at least as powerful as the standard genotype calling approach when the latter controls type I error. An application to the UK10K data reveals novel rare variants in gene BTBD18 associated with childhood onset obesity. The relevant software is freely available.

  6. Risk Factors Associated with False Positive HIV Test Results in a Low-Risk Urban Obstetric Population

    Directory of Open Access Journals (Sweden)

    Tamara T. Chao

    2012-01-01

    Full Text Available Objective. To examine risk factors for false positive HIV enzyme immunoassay (EIA testing at delivery. Study Design. A review of pregnant women who delivered at Parkland Hospital between 2005 and 2008 was performed. Patients routinely received serum HIV EIA testing at delivery, with positive results confirmed through immunofluorescent testing. Demographics, HIV, hepatitis B surface antigen (HBsAg, and rapid plasma reagin (RPR results were obtained. Statistical analyses included Pearson's chi-square and Student's t-test. Results. Of 47,794 patients, 47,391 (99% tested negative, 145 (0.3% falsely positive, 172 (0.4% positive, and 86 (0.2% equivocal or missing HIV results. The positive predictive value of EIA was 54.3%. Patients with false positive results were more likely nulliparous (43% versus 31%, <0.001 and younger (23.9±5.7 versus 26.2±5.9 years, <0.001. HIV positive patients were older than false positive patients and more likely positive for HBsAg and RPR. Conclusion. False positive HIV testing at delivery using EIA is associated with young maternal age and nulliparity in this population.

  7. Validity of subjective assessment as screening tool for dry eye disease and its association with clinical tests

    Institute of Scientific and Technical Information of China (English)

    Kavita; R; Bhatnagar; Sonali; Pote; Sudeep; Pujari; Dhiraj; Deka

    2015-01-01

    AIM: To determine the role of subjective assessment using Mc Monnies dry eye questionnaire in diagnosing dry eye disease and its association with clinical tests.METHODS: There were 500 patients screened for dry eye using Mc Monnies dry eye questionnaire between May to October 2013 at the outpatient Department of Ophthalmology of a medical college hospital. All 500 patients were subjected to clinical tests. Dry eye was defined as having one or more symptoms often or all the time. Positive signs were if one or both eyes revealed tear film breakup time(TBUT) of ≤10s, a Schirmer test score of ≤10 mm, a Rose Bengal staining score of ≥1, a Lissamine green staining score of ≥1 or existence of meibomian gland disease(≥grade 1). Statistical analysis was performed to describe the distribution of symptoms and signs, to assess the correlations between Mc Monnies score(MS) and variable clinical signs of dry eye, and to explore the association between dry eye symptoms and variable clinical signs. Analysis was performed using software package Epi info. A Probability(P) value using Chi-square test of <0.005 was taken as significant.· RESULTS: Dry eye prevalence with symptoms(questionnaire), Schirmer test, TBUT, Rose Bengal staining and Lissamine green staining was 25.6%,15.20%, 20.80%, 23.60%, and 22.60% respectively. Among those with severe symptoms(MS>20), 75.86% had a low TBUT(<10s), 58.62% had a low Schirmer’s I test(≤10 mm),86.20% had Rose Bengal staining score of ≥1, 79.31%had Lissamine green staining score of ≥1. We found statistically significant associations between positive Schirmer test and arthritis(P <0.002), dryness elsewhere(P <0.001), contact lens use(P < 0.002), systemic medication(P <0.0001), sleeping with eyes partly open(P <0.002), history of dry eyes treatment(P <0.0001),environmental factors(P <0.001), swimming(P <0.001).· CONCLUSION: Subjective assessment plays an important role in diagnosing dry eye disease. There is strong correlation

  8. Work-related stress is associated with impaired neuropsychological test performance: a clinical cross-sectional study.

    Science.gov (United States)

    Eskildsen, Anita; Andersen, Lars Peter; Pedersen, Anders Degn; Vandborg, Sanne Kjær; Andersen, Johan Hviid

    2015-01-01

    Patients on sick leave due to work-related stress often complain about impaired concentration and memory. However, it is undetermined how widespread these impairments are, and which cognitive domains are most long-term stress sensitive. Previous studies show inconsistent results and are difficult to synthesize. The primary aim of this study was to examine whether patients with work-related stress complaints have cognitive impairments compared to a matched control group without stress. Our secondary aim was to examine whether the level of self-reported perceived stress is associated with neuropsychological test performance. We used a broad neuropsychological test battery to assess 59 outpatients with work-related stress complaints (without major depression) and 59 healthy controls. We matched the patients and controls pairwise by sex, age and educational level. Compared to controls, patients generally showed mildly reduced performance across all the measured domains of the neuropsychological test battery. However, only three comparisons reached statistical significance (p working memory. There were no statistical significant associations between self-reported perceived stress level and neuropsychological test performance. In conclusion, we recommend that cognitive functions should be considered when evaluating patients with work-related stress complaints, especially when given advice regarding return to work. Since this study had a cross-sectional design, it is still uncertain whether the impairments are permanent. Further study is required to establish causal links between work-related stress and cognitive deficits.

  9. Fine tuning of the digit symbol paired associate recall test for practitioner purposes in clinical and research settings.

    Science.gov (United States)

    Shuttleworth-Edwards, Ann B

    2002-08-01

    Guidelines are presented to facilitate the use of the WAIS Digit Symbol measure of paired associate recall as a neuropsychological instrument. Currently three formal variants of the test exist with accompanying normative data (the original WAIS-R-NI form; a WAIS-R Short Form; a longer WAIS-III form), providing a potential source of confusion which may limit its application. To circumvent this, the present article critically evaluates: (i) variations in test forms and their advantages; (ii) available norms in terms of age and education, with pointers for more differentiated guidelines in this regard; and (iii) the desirability of incorporating a delayed recall variant of the test. Finally, a synopsis of data is presented that supports the screening potential of Digit Symbol paired associate recall in cases of mild neurocognitive dysfunction. For the purposes of this paper, the term WAIS is used with broad reference to all variations of the original Wechsler Adult Intelligence Scale (1955) upon which they were based, including the WAIS-R (1981) and WAIS-III (1997) updated editions, and the South African WAIS (1969). The terms South African WAIS (South African Wechsler Adult Intelligence Scale), WAIS-R (Wechsler Adult Intelligence Scale - Revised), and WAIS-III (Wechsler Adult Intelligence Scale-III), refer to these specific versions of the test.

  10. Anti-PLA2R-associated membranous nephropathy: a review with emphasis on diagnostic testing methods.

    Science.gov (United States)

    VanBeek, Christine; Haas, Mark

    2015-07-01

    The majority of cases of primary membranous nephropathy (MN) are associated with auto-antibodies against the podocyte antigen M-type phospholipase A2 receptor (PLA2R). This particular subset of MN can be diagnosed by identifying anti-PLA2R within patient sera or by detecting PLA2R antigen within glomerular immune complexes in renal biopsy tissue. Since the discovery of anti-PLA2R in 2009, there has been an abundance of literature regarding PLA2R testing as a tool in the diagnosis and management of MN, and these tests are increasingly being implemented in clinical practice. However, questions still remain about a variety of issues such as PLA2R testing in the setting of presumably secondary MN and the significance of PLA2R negative primary MN. The goal of this review is to summarize the current PLA2R testing methods and highlight special features of anti- PLA2R-associated MN.

  11. Testing the Role of Dorsal Premotor Cortex in Auditory-Motor Association Learning Using Transcranical Magnetic Stimulation (TMS)

    Science.gov (United States)

    Lega, Carlotta; Stephan, Marianne A.; Zatorre, Robert J.; Penhune, Virginia

    2016-01-01

    Interactions between the auditory and the motor systems are critical in music as well as in other domains, such as speech. The premotor cortex, specifically the dorsal premotor cortex (dPMC), seems to play a key role in auditory-motor integration, and in mapping the association between a sound and the movement used to produce it. In the present studies we tested the causal role of the dPMC in learning and applying auditory-motor associations using 1 Hz repetitive Transcranical Magnetic Stimulation (rTMS). In this paradigm, non-musicians learn a set of auditory-motor associations through melody training in two contexts: first when the sound to key-press mapping was in a conventional sequential order (low to high tones mapped onto keys from left to right), and then when it was in a novel scrambled order. Participant’s ability to match the four pitches to four computer keys was tested before and after the training. In both experiments, the group that received 1 Hz rTMS over the dPMC showed no significant improvement on the pitch-matching task following training, whereas the control group (who received rTMS to visual cortex) did. Moreover, in Experiment 2 where the pitch-key mapping was novel, rTMS over the dPMC also interfered with learning. These findings suggest that rTMS over dPMC disturbs the formation of auditory-motor associations, especially when the association is novel and must be learned rather explicitly. The present results contribute to a better understanding of the role of dPMC in auditory-motor integration, suggesting a critical role of dPMC in learning the link between an action and its associated sound. PMID:27684369

  12. Impact of measurement error on testing genetic association with quantitative traits.

    Directory of Open Access Journals (Sweden)

    Jiemin Liao

    Full Text Available Measurement error of a phenotypic trait reduces the power to detect genetic associations. We examined the impact of sample size, allele frequency and effect size in presence of measurement error for quantitative traits. The statistical power to detect genetic association with phenotype mean and variability was investigated analytically. The non-centrality parameter for a non-central F distribution was derived and verified using computer simulations. We obtained equivalent formulas for the cost of phenotype measurement error. Effects of differences in measurements were examined in a genome-wide association study (GWAS of two grading scales for cataract and a replication study of genetic variants influencing blood pressure. The mean absolute difference between the analytic power and simulation power for comparison of phenotypic means and variances was less than 0.005, and the absolute difference did not exceed 0.02. To maintain the same power, a one standard deviation (SD in measurement error of a standard normal distributed trait required a one-fold increase in sample size for comparison of means, and a three-fold increase in sample size for comparison of variances. GWAS results revealed almost no overlap in the significant SNPs (p<10(-5 for the two cataract grading scales while replication results in genetic variants of blood pressure displayed no significant differences between averaged blood pressure measurements and single blood pressure measurements. We have developed a framework for researchers to quantify power in the presence of measurement error, which will be applicable to studies of phenotypes in which the measurement is highly variable.

  13. Multilocus association testing of quantitative traits based on partial least-squares analysis.

    Directory of Open Access Journals (Sweden)

    Feng Zhang

    Full Text Available Because of combining the genetic information of multiple loci, multilocus association studies (MLAS are expected to be more powerful than single locus association studies (SLAS in disease genes mapping. However, some researchers found that MLAS had similar or reduced power relative to SLAS, which was partly attributed to the increased degrees of freedom (dfs in MLAS. Based on partial least-squares (PLS analysis, we develop a MLAS approach, while avoiding large dfs in MLAS. In this approach, genotypes are first decomposed into the PLS components that not only capture majority of the genetic information of multiple loci, but also are relevant for target traits. The extracted PLS components are then regressed on target traits to detect association under multilinear regression. Simulation study based on real data from the HapMap project were used to assess the performance of our PLS-based MLAS as well as other popular multilinear regression-based MLAS approaches under various scenarios, considering genetic effects and linkage disequilibrium structure of candidate genetic regions. Using PLS-based MLAS approach, we conducted a genome-wide MLAS of lean body mass, and compared it with our previous genome-wide SLAS of lean body mass. Simulations and real data analyses results support the improved power of our PLS-based MLAS in disease genes mapping relative to other three MLAS approaches investigated in this study. We aim to provide an effective and powerful MLAS approach, which may help to overcome the limitations of SLAS in disease genes mapping.

  14. Association between routine laboratory tests and long-term mortality among acutely admitted older medical patients

    DEFF Research Database (Denmark)

    Klausen, Henrik Hedegaard; Petersen, Janne; Bandholm, Thomas

    2017-01-01

    BACKGROUND: Older people have the highest incidence of acute medical admissions. Old age and acute hospital admissions are associated with a high risk of adverse health outcomes after discharge, such as reduced physical performance, readmissions and mortality. Hospitalisations in this population...... are often by acute admission and through the emergency department. This, along with the rapidly increasing proportion of older people, warrants the need for clinically feasible tools that can systematically assess vulnerability in older medical patients upon acute hospital admission. These are essential...

  15. Functional Task Test: 1. Sensorimotor changes Associated with Postflight Alterations in Astronaut Functional Task Performance

    Science.gov (United States)

    Bloomberg, J. J.; Arzeno, N. H.; Buxton, R. E.; Feiveson, A. H.; Kofman, I. S.; Lee, S. M. C.; Miller, C. A.; Mulavara, A. P.; Platts, S. H.; Peters, B. T.; Phillips, T.; Ploutz-Snyder, L. L.; Reschke, M. F.; Ryder, J. W.; Spiering, B. A.; Stenger, M. B.; Taylor, L. C.; Wickwire, P. J.; Wood, S. J.

    2011-01-01

    Space flight is known to cause alterations in multiple physiological systems including changes in sensorimotor, cardiovascular, and neuromuscular systems. These changes may affect a crewmember s ability to perform critical mission tasks immediately after landing on a planetary surface. The overall goal of this project is to determine the effects of space flight on functional tests that are representative of high priority exploration mission tasks and to identify the key underlying physiological factors that contribute to decrements in performance. This presentation will focus on the sensorimotor contributions to postflight functional performance.

  16. Association between pressure pain sensitivity and autonomic function as assessed by a tilt table test

    DEFF Research Database (Denmark)

    Ballegaard, Søren; Bergmann, Natasha; Karpatschof, Benny;

    2015-01-01

    blood pressure (SBP) and heart rate (HR) responses to TTT; and (2) to test the hypothesis that a reduction of resting PPS raises the PPS, SBP and HR responses to TTT response and lowers risk factors for ANS dysfunction (ANSD). METHODS: Cross-sectional study: In 361 patients with stable ischemic heart...... disease we measured PPS, SBP, and HR during TTT. Intervention study: We reassessed subjects with persistent stress who concluded a stress intervention trial by a second TTT. RESULTS: Cross-sectional study: Resting PPS and the PPS response to TTT were correlated (r = - 0.37). The PPS response to TTT...

  17. Phenomena associated with bench and thermal-vacuum testing of super conductors - Heat pipes.

    Science.gov (United States)

    Marshburn, J. P.

    1973-01-01

    Test failures of heat pipes occur when the functional performance is unable to match the expected design limits or when the power applied to the heat pipe (in the form of heat) is distributed unevenly through the system, yielding a large thermal gradient. When a thermal gradient larger than expected is measured, it normally occurs in the evaporator or condenser sections of the pipe. Common causes include evaporator overheating, condenser dropout, noncondensable gas formation, surge and partial recovery of evaporator temperatures, masking of thermal profiles, and simple malfunctions due to leaks and mechanical failures or flaws. Examples of each of these phenomena are described along with corresponding failure analyses and corrective measures.

  18. A Multi-Marker Genetic Association Test Based on the Rasch Model Applied to Alzheimer's Disease.

    Directory of Open Access Journals (Sweden)

    Wenjia Wang

    Full Text Available Results from Genome-Wide Association Studies (GWAS have shown that the genetic basis of complex traits often include many genetic variants with small to moderate effects whose identification remains a challenging problem. In this context multi-marker analysis at the gene and pathway level can complement traditional point-wise approaches that treat the genetic markers individually. In this paper we propose a novel statistical approach for multi-marker analysis based on the Rasch model. The method summarizes the categorical genotypes of SNPs by a generalized logistic function into a genetic score that can be used for association analysis. Through different sets of simulations, the false-positive rate and power of the proposed approach are compared to a set of existing methods, and shows good performances. The application of the Rasch model on Alzheimer's Disease (AD ADNI GWAS dataset also allows a coherent interpretation of the results. Our analysis supports the idea that APOE is a major susceptibility gene for AD. In the top genes selected by proposed method, several could be functionally linked to AD. In particular, a pathway analysis of these genes also highlights the metabolism of cholesterol, that is known to play a key role in AD pathogenesis. Interestingly, many of these top genes can be integrated in a hypothetic signalling network.

  19. Parental monitoring and knowledge: Testing bidirectional associations with youths' antisocial behavior.

    Science.gov (United States)

    Wertz, Jasmin; Nottingham, Kate; Agnew-Blais, Jessica; Matthews, Timothy; Pariante, Carmine M; Moffitt, Terrie E; Arseneault, Louise

    2016-08-01

    In the present study, we used separate measures of parental monitoring and parental knowledge and compared their associations with youths' antisocial behavior during preadolescence, between the ages of 10 and 12. Parental monitoring and knowledge were reported by mothers, fathers, and youths taking part in the Environmental Risk (E-Risk) Longitudinal Twin Study that follows 1,116 families with twins. Information on youths' antisocial behavior was obtained from mothers as well as teachers. We report two main findings. First, longitudinal cross-lagged models revealed that greater parental monitoring did not predict less antisocial behavior later, once family characteristics were taken into account. Second, greater youth antisocial behavior predicted less parental knowledge later. This effect of youths' behavior on parents' knowledge was consistent across mothers', fathers', youths', and teachers' reports, and robust to controls for family confounders. The association was partially genetically mediated according to a Cholesky decomposition twin model; youths' genetically influenced antisocial behavior led to a decrease in parents' knowledge of youths' activities. These two findings question the assumption that greater parental monitoring can reduce preadolescents' antisocial behavior. They also indicate that parents' knowledge of their children's activities is influenced by youths' behavior.

  20. Multiple genetic variant association testing by collapsing and kernel methods with pedigree or population structured data.

    Science.gov (United States)

    Schaid, Daniel J; McDonnell, Shannon K; Sinnwell, Jason P; Thibodeau, Stephen N

    2013-07-01

    Searching for rare genetic variants associated with complex diseases can be facilitated by enriching for diseased carriers of rare variants by sampling cases from pedigrees enriched for disease, possibly with related or unrelated controls. This strategy, however, complicates analyses because of shared genetic ancestry, as well as linkage disequilibrium among genetic markers. To overcome these problems, we developed broad classes of "burden" statistics and kernel statistics, extending commonly used methods for unrelated case-control data to allow for known pedigree relationships, for autosomes and the X chromosome. Furthermore, by replacing pedigree-based genetic correlation matrices with estimates of genetic relationships based on large-scale genomic data, our methods can be used to account for population-structured data. By simulations, we show that the type I error rates of our developed methods are near the asymptotic nominal levels, allowing rapid computation of P-values. Our simulations also show that a linear weighted kernel statistic is generally more powerful than a weighted "burden" statistic. Because the proposed statistics are rapid to compute, they can be readily used for large-scale screening of the association of genomic sequence data with disease status.

  1. Diagnostic tests for the detection of human papillomavirus-associated cervical lesions.

    Science.gov (United States)

    Reuschenbach, Miriam; von Knebel Doeberitz, Magnus

    2013-01-01

    Current diagnostic approaches for primary cervical cancer screening, work-up of equivocal or positive screening results or follow- up after treatment of precancerous lesions primarily rely on the morphologic interpretation of squamous epithelial cells (Pap cytology), in some setting accompanied by the detection of human papillomavirus DNA and have largely contributed to remarkable reduction of disease incidence in countries with implemented screening programs. However, these approaches are limited by a poor sensitivity and reproducibility of Pap cytology and low specificity for high grade cervical intraepithelial neoplasia of HPV DNA detection assays. Early detection might be improved by complementing or even replacing these tests by markers which are more directly related to molecular events triggering HPV-induced carcinogenesis and thereby might deliver more accurate diagnostic performance. The delineation of molecular changes which occur during different stages of HPV infections and the identification of changes which induce neoplastic alterations allow for the detection of markers that specifically highlight the transforming stage of the infection where viral oncogenes are overexpressed and therefore allow for a more specific diagnosis of lesions that require treatment. The evaluation of such markers in clinical studies revealed that some indeed show an improved diagnostic performance compared to Pap cytology or HPV DNA tests only.

  2. The Total Work Measured During a High Intensity Isokinetic Fatigue Test Is Associated With Anaerobic Work Capacity

    Science.gov (United States)

    Bosquet, Laurent; Gouadec, Kenan; Berryman, Nicolas; Duclos, Cyril; Gremeaux, Vincent; Croisier, Jean Louis

    2016-01-01

    The purpose of the study was to determine whether total work measured during a high intensity isokinetic fatigue test (TWFAT) could be considered as a valid measure of anaerobic work capacity (AWC), such as determined by total work measured during a Wingate Anaerobic Test (TWWAnT). Twenty well-trained cyclists performed 2 randomly ordered sessions involving a high intensity isokinetic fatigue test consisting in 30 reciprocal maximal concentric contractions of knee flexors and extensors at 180°·s-1, and a Wingate Anaerobic Test. We found that TWFAT of knee extensors was largely lower than TWWAnT (4151 ± 691 vs 22313 ± 2901 J, respectively, p knee flexors (2151 ± 540 J) was largely lower than TWWAnT (p knee flexors and knee extensors into a single measure (6302 ± 818 J) did not changed neither improved these observations. We still found a large difference with TWWAnT (p knee extensors could be considered as a valid measure of AWC, since both measure were highly associated. However, the mean difference between both measures and their 95% LoA were too large to warrant interchangeability. Key points Total work performed during a high intensity isokinetic fatigue test can be considered as a valid measure of anaerobic work capacity (as determined by total work performance during a 30-s Wingate anaerobic test). The 95% limits of agreement are two large to allow a direct comparison between both measures. In other words, it is not possible to estimate the magnitude of performance improvement during a 30-s Wingate anaerobic test from that observed during a high intensity isokinetic fatigue test. In addition to provide sport scientists and coaches with measures of peak torque and ratios between agonists and antagonists muscles in a perspective of injury prevention, isokinetic dynamometry can also be used in the physiological assessment of athletes. However, some precautions should be taken in the interpretation of data. PMID:26957935

  3. Observations on Faults and Associated Permeability Structures in Hydrogeologic Units at the Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    Prothro, Lance B.; Drellack, Sigmund L.; Haugstad, Dawn N.; Huckins-Gang, Heather E.; Townsend, Margaret J.

    2009-03-30

    Observational data on Nevada Test Site (NTS) faults were gathered from a variety of sources, including surface and tunnel exposures, core samples, geophysical logs, and down-hole cameras. These data show that NTS fault characteristics and fault zone permeability structures are similar to those of faults studied in other regions. Faults at the NTS form complex and heterogeneous fault zones with flow properties that vary in both space and time. Flow property variability within fault zones can be broken down into four major components that allow for the development of a simplified, first approximation model of NTS fault zones. This conceptual model can be used as a general guide during development and evaluation of groundwater flow and contaminate transport models at the NTS.

  4. High expression of testes-specific protease 50 is associated with poor prognosis in colorectal carcinoma.

    Directory of Open Access Journals (Sweden)

    Lei Zheng

    Full Text Available BACKGROUND: Testes-specific protease 50 (TSP50 is normally expressed in testes and abnormally expressed in breast cancer, but whether TSP50 is expressed in colorectal carcinoma (CRC and its clinical significance is unclear. We aimed to detect TSP50 expression in CRC, correlate it with clinicopathological factors, and assess its potential diagnostic and prognostic value. METHODOLOGY/PRINCIPAL FINDINGS: TSP50 mRNAs and proteins were detected in 7 CRC cell lines and 8 CRC specimens via RT-PCR and Western blot analysis. Immunohistochemical analysis of TSP50, p53 and carcinoembryonic antigen (CEA with tissue microarrays composed of 95 CRCs, 20 colorectal adenomas and 20 normal colorectal tissues were carried out and correlated with clinicopathological characteristics and disease-specific survival for CRC patients. There was no significant correlation between the expression levels of TSP50 and p53 (P = 0.751 or CEA (P = 0.663. Abundant expression of TSP50 protein was found in CRCs (68.4% while it was poorly expressed in colorectal adenomas and normal tissues (P<0.0001. Thus, CRCs can be distinguished from them with high specificity (92.5% and positive predictive value (PPV, 95.6%. The survival of CRC patients with high TSP50 expression was significantly shorter than that of the patients with low TSP50 expression (P = 0.010, specifically in patients who had early-stage tumors (stage I and II; P = 0.004. Multivariate Cox regression analysis indicated that high TSP50 expression was a statistically significant independent risk factor (hazard ratio  = 2.205, 95% CI = 1.214-4.004, P = 0.009. CONCLUSION: Our data demonstrate that TSP50 is a potential effective indicator of poor survival for CRC patients, especially for those with early-stage tumors.

  5. Combining Multiple Hypothesis Testing with Machine Learning Increases the Statistical Power of Genome-wide Association Studies

    Science.gov (United States)

    Mieth, Bettina; Kloft, Marius; Rodríguez, Juan Antonio; Sonnenburg, Sören; Vobruba, Robin; Morcillo-Suárez, Carlos; Farré, Xavier; Marigorta, Urko M.; Fehr, Ernst; Dickhaus, Thorsten; Blanchard, Gilles; Schunk, Daniel; Navarro, Arcadi; Müller, Klaus-Robert

    2016-11-01

    The standard approach to the analysis of genome-wide association studies (GWAS) is based on testing each position in the genome individually for statistical significance of its association with the phenotype under investigation. To improve the analysis of GWAS, we propose a combination of machine learning and statistical testing that takes correlation structures within the set of SNPs under investigation in a mathematically well-controlled manner into account. The novel two-step algorithm, COMBI, first trains a support vector machine to determine a subset of candidate SNPs and then performs hypothesis tests for these SNPs together with an adequate threshold correction. Applying COMBI to data from a WTCCC study (2007) and measuring performance as replication by independent GWAS published within the 2008-2015 period, we show that our method outperforms ordinary raw p-value thresholding as well as other state-of-the-art methods. COMBI presents higher power and precision than the examined alternatives while yielding fewer false (i.e. non-replicated) and more true (i.e. replicated) discoveries when its results are validated on later GWAS studies. More than 80% of the discoveries made by COMBI upon WTCCC data have been validated by independent studies. Implementations of the COMBI method are available as a part of the GWASpi toolbox 2.0.

  6. Estrogen effects on actin cytoskeletal and endocytic proteins associated with tubulobulbar complex disruption in rat testes.

    Science.gov (United States)

    Upadhyay, Rahul D; Kumar, Anita V; Sonawane, Shobha; Gaonkar, Reshma; Balasinor, Nafisa H

    2013-10-01

    Tubulobulbar complexes (TBCs), evaginations of mature spermatids, penetrate into the surrounding Sertoli cell cytoplasm of testis seminiferous epithelium during rat spermatogenesis. These structures prepare mature spermatids for their release into the seminiferous tubular lumen via a process called spermiation. Based on their functions of transient attachment and endocytosis, many actin-regulatory and endocytic proteins are associated with TBCs. Previously, exogenous 17β-estradiol administration to adult male rats showed spermiation failure that was attributed to TBC disruption. To determine the molecular basis of estrogen-induced TBC disruption, we examined the expressions and localizations of actin-regulatory proteins, endocytic proteins, Rho-GTPases, and phosphorylation in TBCs during sperm release. Results demonstrated absence of neural Wiscott Aldrich syndrome protein, cortactin, adaptor-related protein complex 2 sigma-1 subunit, dynamin 2, cell division control protein 42, and phosphocortactin in the concavity of spermatid head where TBCs are present without change in their protein expression levels. Absence of these proteins could have led to collapse of the TBC structure which is involved in its formation and function.

  7. Association testing to detect gene-gene interactions on sex chromosomes in trio data

    Directory of Open Access Journals (Sweden)

    Yeonok eLee

    2013-11-01

    Full Text Available Autism Spectrum Disorder (ASD occurs more often among males than females in a 4:1 ratio. Among theories used to explain the causes of ASD, the X chromosome and the Y chromosome theories attribute ASD to X-linked mutation and the male-limited gene expressions on the Y chromosome, respectively. Despite the rationale of the theory, studies have failed to attribute the sex-biased ratio to the significant linkage or association on the regions of interest on X chromosome. We further study the gender biased ratio by examining the possible interaction effects between two genes in the sex chromosomes. We propose a logistic regression model with mixed effects to detect gene-gene interactions on sex chromosomes. We investigated the power and type I error rates of the approach for a range of minor allele frequencies and varying linkage disequilibrium between markers and QTLs. We also evaluated the robustness of the model to population stratification. We applied the model to a trio-family data set with an ASD affected male child to study gene-gene interactions on sex chromosomes.

  8. False Human Immunodeficiency Virus Test Results Associated with Rheumatoid Factors in Rheumatoid Arthritis

    Institute of Scientific and Technical Information of China (English)

    Yun-chun Li; Fan Yang; Xiao-yun Ji; Zhong-jun Fang; Jun Liu; Yue Wang

    2014-01-01

    Objective To investigate if immunological factors associated with rheumatoid arthritis (RA) affect the result of human immunodeficiency virus (HIV) screening by electrochemiluminescence immunoassay (ECLIA) and enzyme-linked immunosorbent assay (ELISA). Methods 100 RA cases were enrolled from January 2012 to February 2013 into this study. HIV screening was conducted with ECLIA detecting both HIV-1 p24 antigen, HIV-1 and HIV-2 antibodies, with ELISA and colloidal gold method detecting HIV-1 and HIV-2 antibodies. The samples producing positive results were submitted to the Center for Disease Control for confirmation using Western blotting method. The antibody titers of rheumatoid factors (RF) including RF-IgG, RF-IgM, RF-IgA, and CCP-IgG were analyzed by ELISA. Results The HIV positive-rate determined by ECLIA was significantly higher than that by ELISA and colloidal gold method (P Conclusion Immunological factors, including RF and anti-CCP antibody, may influence the screening of HIV by ECLIA, producing false-positive result.

  9. Testing Disk-Wind Models with Quasar CIV 1549Å Associated Absorption Lines

    DEFF Research Database (Denmark)

    Vestergaard, Marianne

    2012-01-01

    Narrow associated C IV 1549Å absorption lines (NALs) with a rest equivalent width EW =3 Å detected in z ˜ 2 radio-loud and radio-quiet quasars, (a) exhibit evidence of an origin in radiatively accelerated gas, and (b) may be closely related to broad absorption line (BAL) outflows. These NALs...... and the few BALs detected in this quasar sample obey key predictions of models of radiatively driven disk-winds in which (1) the local disk luminosity launches the wind, (2) the central UV radiation drives it outwards, and (3) the wind acceleration (i.e., terminal velocity) depends on the strength of the X......-ray to UV emission ratio, i.e., aOX. The latter means that quasars with flat aOX (like radio-louds) should not have strong, high-velocity (BAL-like) outflows. These results are of interest not only to studies of disk wind scenarios and quasar structure, but also to studies of quasar feedback: NALs...

  10. Assessing Sexual Interest in Children Using the Go/No-Go Association Test.

    Science.gov (United States)

    Bartels, Ross M; Beech, Anthony R; Harkins, Leigh; Thornton, David

    2017-01-01

    The present study investigated whether a latency-based Go/No-Go Association Task (GNAT) could be used as an indirect measure of sexual interest in children. A sample of 29 individuals with a history of exclusive extrafamilial offenses against a child and 15 individuals with either a history of exclusive intrafamilial or mixed offenses (i.e., against both adults and children) were recruited from a treatment center in the United States. Also, a sample of 26 nonoffenders was recruited from a university in the United Kingdom. All participants completed the Sexual Fantasy-GNAT, a Control-GNAT, and two self-report measures of sexual fantasy. It was hypothesized that, relative to the two comparison groups, the extrafamilial group would respond faster on the block that paired "sexual fantasy" and "children." Also, GNAT scores were expected to correlate with child-related sexual fantasies. Support was found for both hypotheses. Response-latency indices were also found to effectively distinguish the extrafamilial group, as well as those who self-reported using child-related sexual fantasies. The implications of these findings, along with the study's limitations and suggestions for future research, are discussed.

  11. Tests for host-associated fitness trade-offs in the milkweed-oleander aphid.

    Science.gov (United States)

    Groeters, Francis R

    1993-03-01

    The milkweed-oleander aphid, Aphis nerii (Boyer de Fonscolombe) (Homoptera: Aphididae), feeds on different milkweed species in northern California than in Puerto Rico. The hosts vary, primarily between regions, for both identity and quantity of cardenolides that the aphid sequesters for its own defense. In tests for hostassociated fitness trade-offs only one case was found in which host plant and fitness corresponded, but the effect was not significant. However, power to detect fitness trade-offs was limited and the possibility of considerable differences in fitness on a particular host for aphids from different hosts cannot be excluded. On Californian host species, among which migration is common, generalized host use could result from selection for general-purpose genotypes. However, this explanation cannot apply to generalized host use of Californian and Puerto Rican milkweeds because the regions are isolated by distance. A cardenolide sequestration mechanism that is free of substantial energy costs could provide the basis for fitness homeostasis on variable host plants that makes trade-offs unlikely even on hosts from different regions.

  12. Carbon-14 urea breath test for the diagnosis of Campylobacter pylori associated gastritis

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, B.J.; Surveyor, I.

    1988-01-01

    Urease in the human gastric mucosa is a marker for infection with Campylobacter pylori (CP), an organism suspected of causing chronic gastritis and peptic ulceration. To detect gastric urease, we examined 32 patients who were being evaluated for possible peptic ulcer disease. Fasting patients were given 10 microCi (370 kBq) of /sup 14/C-labeled urea. Breath samples were collected in hyamine at intervals between 1 and 30 min. The amount of /sup 14/C collected at these times was expressed as: body weight X (% of administered dose of /sup 14/C in sample)/(mmol of CO/sub 2/ collected). The presence of C. pylori colonization was also determined by examination of multiple endoscopic gastric biopsy specimens. On average, patients who were proven to have C. pylori infection exhaled 20 times more labeled CO/sub 2/ than patients who were not infected. The difference between infected patients and C. pylori negative control patients was highly significant at all time points between 2 and 30 min after ingestion of the radionuclide (p less than 0.0001). The noninvasive urea breath is less expensive than endoscopic biopsy of the stomach and more accurate than serology as a means of detecting Campylobacter pylori infection. Because the test detects actual viable CP organisms, it can be used to confirm eradication of the bacterium after antibacterial therapy.

  13. Testing the association between psychosocial job strain and adverse birth outcomes - design and methods

    Directory of Open Access Journals (Sweden)

    Thulstrup Ane M

    2011-04-01

    Full Text Available Abstract Background A number of studies have examined the effects of prenatal exposure to stress on birth outcomes but few have specifically focused on psychosocial job strain. In the present protocol, we aim to examine if work characterised by high demands and low control, during pregnancy, is associated with the risk of giving birth to a child born preterm or small for gestational age. Methods and design We will use the Danish National Birth Cohort where 100.000 children are included at baseline. In the present study 49,340 pregnancies will be included. Multinomial logistic regression will be applied to estimate odds ratios for the outcomes: preterm; full term but small for gestational age; full term but large for gestational age, as a function of job-strain (high strain, active and passive versus low strain. In the analysis we control for maternal age, Body Mass Index, parity, exercise, smoking, alcohol use, coffee consumption, type of work (manual versus non-manual, maternal serious disease and parents' heights as well as gestational age at interview. Discussion The prospective nature of the design and the high number of participants strengthen the study. The large statistical power allows for interpretable results regardless of whether or not the hypotheses are confirmed. This is, however, not a controlled study since all kinds of 'natural' interventions takes place throughout pregnancy (e.g. work absence, medical treatment and job-redesign. The analysis will be performed from a public health perspective. From this perspective, we are not primarily interested in the effect of job strain per se but if there is residual effect of job strain after naturally occurring preventive measures have been taken.

  14. Testing of candidate single nucleotide variants associated with paclitaxel neuropathy in the trial NCCTG N08C1 (Alliance).

    Science.gov (United States)

    Boora, Ganesh K; Kanwar, Rahul; Kulkarni, Amit A; Abyzov, Alexej; Sloan, Jeff; Ruddy, Kathryn J; Banck, Michaela S; Loprinzi, Charles L; Beutler, Andreas S

    2016-04-01

    Paclitaxel-induced peripheral neuropathy (PIPN) cannot be predicted from clinical parameters and might have a pharmacogenomic basis. Previous studies identified single nucleotide variants (SNV) associated with PIPN. However, only a subset of findings has been confirmed to date in more than one study, suggesting a need for further re-testing and validation in additional clinical cohorts. Candidate PIPN-associated SNVs were identified from the literature. SNVs were retested in 119 patients selected by extreme phenotyping from 269 in NCCTG N08C1 (Alliance) as previously reported. SNV genotyping was performed by a combination of short-read sequencing analysis and Taqman PCR. These 22 candidate PIPN SNVs were genotyped. Two of these, rs7349683 in the EPHA5 and rs3213619 in ABCB1 were found to be significantly associated with PIPN with an Odds ratios OR = 2.07 (P = 0.02) and OR = 0.12 (P = 0.03), respectively. In addition, three SNVs showed a trend toward a risk- or protective effect that was consistent with previous reports. The rs10509681 and rs11572080 in the gene CYP2C8*3 showed risk effect with an OR = 1.49 and rs1056836 in CYP1B1 showed a protective effect with an OR = 0.66. None of the other results supported the previously reported associations, including some SNVs displaying an opposite direction of effect from previous reports, including rs1058930 in CYP2C8, rs17222723 and rs8187710 in ABCC2, rs10771973 in FGD4, rs16916932 in CACNB2 and rs16948748 in PITPNA. Alliance N08C1 validated or supported a minority of previously reported SNV-PIPN associations. Associations previously reported by multiple studies appeared to have a higher likelihood to be validated by Alliance N08C1.

  15. Leukocytes as risk markers for cardiovascular disease in adolescents: association with birth characteristics, nutritional status and biochemical tests

    Science.gov (United States)

    do Prado, Pedro Paulo; de Faria, Franciane Rocha; de Faria, Eliane Rodrigues; Franceschini, Sylvia do Carmo Castro; Priore, Silvia Eloiza

    2016-01-01

    Abstract Objective: To evaluate the correlation between the number of leukocytes and cardiovascular risks associated with birth characteristics, nutritional status and biochemical tests. Methods: Cross-sectional study developed with 475 adolescents, born between 1992 and 2001, in the municipality of Viçosa (MG). Maternal medical records were analyzed in the hospital units, and the following was recorded: birth weight and length, head circumference, chest circumference, Apgar score, gestational age. In adolescents, body mass index, skinfold thickness, body composition, blood count, biochemical tests and clinical variables were also assessed. The statistical analyses was carried out using Statistical Package for Social Sciences (SPSS) version 20.0 and Data Analysis and Statistical Software (STATA) with Kruskal–Wallis, Mann–Whitney, chi-square or Fisher's exact tests and Linear Regression. Significance level was set at α<0.05. The study was approved by the Research Ethics Committee of UFV for studies with human subjects. Results: Weight and birth length, head and chest circumference were higher among boys. In adolescents, the number of leukocytes was higher in individuals with excess weight and body fat and high adiposity index, waist-to-height ratio and waist circumference. Only altered triglycerides showed differences between leukocyte medians. Regardless of the anthropometric variable of the final regression model, the stage of adolescence, number of platelets, eosinophils, monocytes and lymphocytes were associated with the increase in leukocytes. Conclusions: The birth variables were not associated with changes in leukocyte numbers, whereas the anthropometric variables were good indicators for a higher leukocyte count, regardless of the stage of adolescence and gender. PMID:26572104

  16. Leukocytes as risk markers for cardiovascular disease in adolescents: association with birth characteristics, nutritional status and biochemical tests

    Directory of Open Access Journals (Sweden)

    Pedro Paulo do Prado Junior

    2016-03-01

    Full Text Available Abstract Objective: To evaluate the correlation between the number of leukocytes and cardiovascular risks associated with birth characteristics, nutritional status and biochemical tests. Methods: Cross-sectional study developed with 475 adolescents, born between 1992 and 2001, in the municipality of Viçosa (MG. Maternal medical records were analyzed in the hospital units, and the following was recorded: birth weight and length, head circumference, chest circumference, Apgar score, gestational age. In adolescents, body mass index, skinfold thickness, body composition, blood count, biochemical tests and clinical variables were also assessed. The statistical analyses was carried out using Statistical Package for Social Sciences (SPSS version 20.0 and Data Analysis and Statistical Software (STATA with Kruskal–Wallis, Mann–Whitney, chi-square or Fisher's exact tests and Linear Regression. Significance level was set at α<0.05. The study was approved by the Research Ethics Committee of UFV for studies with human subjects. Results: Weight and birth length, head and chest circumference were higher among boys. In adolescents, the number of leukocytes was higher in individuals with excess weight and body fat and high adiposity index, waist-to-height ratio and waist circumference. Only altered triglycerides showed differences between leukocyte medians. Regardless of the anthropometric variable of the final regression model, the stage of adolescence, number of platelets, eosinophils, monocytes and lymphocytes were associated with the increase in leukocytes. Conclusions: The birth variables were not associated with changes in leukocyte numbers, whereas the anthropometric variables were good indicators for a higher leukocyte count, regardless of the stage of adolescence and gender.

  17. Investigation of the association between glaucoma and Helicobacter pylori infection using the {sup 14}C-urea breath test

    Energy Technology Data Exchange (ETDEWEB)

    Tuzcu, Esra Ayhan; Aydogan, Fusun; Motor, Vicdan Koksaldi; Ilhan, Ozgur; Daglioglu, Mutlu Cihan; Coskun, Mesut; Parlakfikirer, Nihan; Keskin, Ugurcan, E-mail: drayhant@hotmail.com [Medical Faculty, Mustafa Kemal University, Hatay (Turkey)

    2015-07-01

    Purpose: to investigate the association between glaucoma and Helicobacter pylori infection by evaluating for the presence of H. pylori infection in patients with glaucoma using the 14C-urea breath test (14C-UBT). Methods: Using 14C-UBT, H. pylori infection positivity was compared between a group of patients with primary open-angle glaucoma and a control group with normal intraocular pressure and a normal optic disc or normal perimetry. Results: the 14C-UBT was positive in 18 (51.42%) out of 35 patients in the glaucoma group and in 15 (42.85%) out of 35 patients in the control group. H. pylori infection positivity rates were similar between the glaucoma and control groups (p>0.05). Conclusion: according to the 14C-UBT, there is no association between primary open-angle glaucoma and H. pylori infection. (author)

  18. Abattoir-based study investigating the association between gross pathological lesions and serological tests for Salmonella infection in pigs.

    Science.gov (United States)

    Smith, R P; Sanchez-Vazquez, M J; Cook, A J C; Edwards, S A

    2011-03-05

    Abattoir data collected from three British pig health monitoring schemes were combined to investigate the associations between Salmonella infection and the presence of gross lesions detected in slaughtered pigs. Each set of results was linked back to the farm from which the pigs were submitted, and the Salmonella results and lesions reports were connected at farm level. Salmonella infection was determined through meat juice ELISA (MJE), and the health conditions were assessed by postmortem inspection. The final dataset contained 873 slapmarks, with an average of 215 samples tested by MJE, and 355 pigs that were assessed for health conditions, per slapmark. Each of the health assessment conditions was individually analysed by regression models to investigate associations with the MJE results, accounting for clustering at the slapmark level and also for seasonality. A multivariable model was also used to estimate the strength of association with MJE results when all the health conditions were entered into the model. The results showed positive associations between Salmonella and enzootic pneumonia-like lesions, milk spots, peritonitis and pericarditis.

  19. Recommendations from multi-disciplinary focus groups on cascade testing and genetic counseling for fragile X-associated disorders.

    Science.gov (United States)

    McConkie-Rosell, Allyn; Abrams, Liane; Finucane, Brenda; Cronister, Amy; Gane, Louise W; Coffey, Sarah M; Sherman, Stephanie; Nelson, Lawrence M; Berry-Kravis, Elizabeth; Hessl, David; Chiu, Sufen; Street, Natalie; Vatave, Ajay; Hagerman, Randi J

    2007-10-01

    The purpose of this paper is to report the outcome of a collaborative project between the Fragile X Research and Treatment Center at the Medical Investigation of Neurodevelopmental Disorders (M.I.N.D.) Institute at the University of California at Davis, the National Fragile X Foundation (NFXF), and the Centers for Disease Control and Prevention (CDC). The objective of this collaboration was to develop and disseminate protocols for genetic counseling and cascade testing for the multiple disorders associated with the fragile X mental retardation 1 (FMR1) mutation. Over the last several years, there has been increasing insight into the phenotypic range associated with both the premutation and the full mutation of the FMR1 gene. To help develop recommendations related to screening for fragile X-associated disorders, four, two day advisory focus group meetings were conducted, each with a different theme. The four themes were: (1) fragile X-associated tremor/ataxia syndrome (FXTAS); (2) premature ovarian failure (POF) and reproductive endocrinology; (3) psychiatric, behavioral and psychological issues; and (4) population screening and related ethical issues.

  20. Testing the Disk-Locking Paradigm: An Association Between U-V Excess and Rotation in NGC 2264

    OpenAIRE

    Fallscheer, Cassandra; Herbst, William

    2006-01-01

    We present some results from a UVI photometric study of a field in the young open cluster NGC 2264 aimed, in part, at testing whether accretion in pre-main sequence stars is linked to rotation. We confirm that U-V excess is well correlated with H-alpha equivalent width for the stars in our sample. We show that for the more massive stars in the cluster sample (roughly 0.4-1.2 M_sun) there is also a significant association between U-V excess and rotation, in the sense that slow rotators are mor...

  1. CAPL: a novel association test using case-control and family data and accounting for population stratification.

    Science.gov (United States)

    Chung, Ren-Hua; Schmidt, Michael A; Morris, Richard W; Martin, Eden R

    2010-11-01

    The recent successes of GWAS based on large sample sizes motivate combining independent datasets to obtain larger sample sizes and thereby increase statistical power. Analysis methods that can accommodate different study designs, such as family-based and case-control designs, are of general interest. However, population stratification can cause spurious association for population-based association analyses. For family-based association analysis that infers missing parental genotypes based on the allele frequencies estimated in the entire sample, the parental mating-type probabilities may not be correctly estimated in the presence of population stratification. Therefore, any approach to combining family and case-control data should also properly account for population stratification. Although several methods have been proposed to accommodate family-based and case-control data, all have restrictions. Most of them require sampling a homogeneous population, which may not be a reasonable assumption for data from a large consortium. One of the methods, FamCC, can account for population stratification and uses nuclear families with arbitrary number of siblings but requires parental genotype data, which are often unavailable for late-onset diseases. We extended the family-based test, Association in the Presence of Linkage (APL), to combine family and case-control data (CAPL). CAPL can accommodate case-control data and families with multiple affected siblings and missing parents in the presence of population stratification. We used simulations to demonstrate that CAPL is a valid test either in a homogeneous population or in the presence of population stratification. We also showed that CAPL can have more power than other methods that combine family and case-control data.

  2. ST segment elevation in lead aVR during exercise testing is associated with LAD stenosis

    Energy Technology Data Exchange (ETDEWEB)

    Neill, Johanne; Harbinson, Mark [Royal Victoria Hospital, Regional Medical Cardiology Centre, Belfast (United Kingdom); Queens University, Belfast (United Kingdom); Shannon, Heather J.; Morton, Amanda; Muir, Alison R.; Adgey, Jennifer A. [Royal Victoria Hospital, Regional Medical Cardiology Centre, Belfast (United Kingdom)

    2007-03-15

    To evaluate, in patients with chest pain, the diagnostic value of ST elevation (STE) in lead aVR during stress testing prior to {sup 99m} Tc-sestamibi scanning correlating ischaemic territory with angiographic findings. Consecutive patients attending for {sup 99m} Tc-sestamibi myocardial perfusion imaging (MPI) completed a treadmill protocol. Peak exercise ECGs were coded. STE {>=}0.05 mV in lead aVR was considered significant. Gated perfusion images and findings at angiography were assessed. STE in lead aVR occurred in 25% (138/557) of the patients. More patients with STE in aVR had a reversible defect on imaging compared with those who had no STE in aVR (41%, 56/138 vs 27%, 114/419, p=0.003). Defects indicating a left anterior descending artery (LAD) culprit lesion were more common in the STE in aVR group (20%, 27/138 vs 9%, 39/419, p=0.001). There was a trend towards coronary artery stenosis (>70%) in a double vessel distribution involving the LAD in those patients who had STE in aVR compared with those who did not (22%, 8/37 vs 5%, 4/77, p=0.06). Logistic regression analysis demonstrated that STE in aVR (OR 1.36, p=0.233) is not an independent predictor of inducible abnormality when adjusted for STD >0.1 mV (OR 1.69, p=0.026). However, using anterior wall defect as an end-point, STE in aVR (OR 2.77, p=0.008) was a predictor even after adjustment for STD (OR 1.43, p=0.281). STE in lead aVR during exercise does not diagnose more inducible abnormalities than STD alone. However, unlike STD, which is not predictive of a territory of ischaemia, STE in aVR may indicate an anterior wall defect. (orig.)

  3. A new test battery to assess aphasic disturbances and associated cognitive dysfunctions -- German normative data on the aphasia check list.

    Science.gov (United States)

    Kalbe, Elke; Reinhold, Nadine; Brand, Matthias; Markowitsch, Hans J; Kessler, Josef

    2005-10-01

    Aphasia, defined as an acquired impairment of linguistic abilities, can be accompanied by a diversity of neuropsychological dysfunction. Accordingly, the necessity to include cognitive testing in the diagnosis of aphasia is increasingly recognized. Here we present the Aphasia Check List (ACL), a new test battery for the assessment of aphasic and associated cognitive disorders. The language part of the battery provides a differentiated profile of important linguistic abilities. In addition, the ACL includes nonverbal screening tests for three neuropsychological domains: memory, attention, and reasoning. Dysfunctions in these domains have been observed in aphasic patients and can have an impact on language function. The ACL is applicable to patients with language disturbances of different etiologies, different stages of disease, and to patients with mild to severe aphasia. As the entire test duration is only about 30 minutes, the ACL is also economically valuable. It thus presents an adequate starting point in aphasia diagnosis for a wide range of patients. Here we describe the construction of the ACL, and the normative study of its original German version with 154 aphasic patients and 106 healthy comparison subjects. The ACL cognition part revealed additional neuropsychological dysfunction in the aphasia group. We present the patterns of these dysfunctions and their correlations with language deficits.

  4. Power and related statistical properties of conditional likelihood score tests for association studies in nuclear families with parental genotypes.

    Science.gov (United States)

    Li, Z; Gastwirth, J L; Gail, M H

    2005-05-01

    Both population based and family based case control studies are used to test whether particular genotypes are associated with disease. While population based studies have more power, cryptic population stratification can produce false-positive results. Family-based methods have been introduced to control for this problem. This paper presents the full likelihood function for family-based association studies for nuclear families ascertained on the basis of their number of affected and unaffected children. The likelihood of a family factors into the probability of parental mating type, conditional on offspring phenotypes, times the probability of offspring genotypes given their phenotypes and the parental mating type. The first factor can be influenced by population stratification, whereas the latter factor, called the conditional likelihood, is not. The conditional likelihood is used to obtain score tests with proper size in the presence of population stratification (see also Clayton (1999) and Whittemore & Tu (2000)). Under either the additive or multiplicative model, the TDT is known to be the optimal score test when the family has only one affected child. Thus, the class of score tests explored can be considered as a general family of TDT-like procedures. The relative informativeness of the various mating types is assessed using the Fisher information, which depends on the number of affected and unaffected offspring and the penetrances. When the additive model is true, families with parental mating type Aa x Aa are most informative. Under the dominant (recessive) model, however, a family with mating type Aa x aa(AA x Aa) is more informative than a family with doubly heterozygous (Aa x Aa) parents. Because we derive explicit formulae for all components of the likelihood, we are able to present tables giving required sample sizes for dominant, additive and recessive inheritance models.

  5. Correlation between HRCT findings, pulmonary function tests and bronchoalveolar lavage cytology in interstitial lung disease associated with rheumatoid arthritis

    Energy Technology Data Exchange (ETDEWEB)

    Biederer, J.; Muhle, C.; Heller, M.; Reuter, M. [Department of Diagnostic Radiology, Christian Albrechts University Kiel, Arnold-Heller-Strasse 9, 24105, Kiel (Germany); Schnabel, A.; Gross, W.L. [Department of Clinical Rheumatology, University of Luebeck, Luebeck (Germany); Rheumaklinik Bad Bramstedt, Bad Bramstedt (Germany)

    2004-02-01

    A prospective study correlating high-resolution computed tomography (HRCT), lung function tests (PFT) and bronchoalveolar lavage (BAL) cytology in patients with interstitial lung disease (ILD) associated with rheumatoid arthritis (RA). Fifty-three RA patients with suspected ILD (19 men, 34 women) underwent 71 HRCT (14 of 53 with sequential HRCT, mean follow-up 24.3 months). The HRCT evaluation by two observers on consensus included a semi-quantitative characterisation of lesion pattern and profusion on representative anatomical levels. Fifty-two HRCT were followed by PFT and BAL. Agreement or discordance of HRCT-, PFT- and BAL findings were analysed with Pearson's correlation, {kappa} score and McNemar's test. Tobacco-fume exposure was estimated in pack years. Smoking/non-smoking groups were compared with Student's t test. In 49 of 53 patients, HRCT was suggestive of ILD associated with RA (66 of 71 HRCT). Reticular lesions were found in 40 of 53 patients, in 15 of 40 presenting as mixed pattern with ground-glass opacities (GGO). Pure reticular patterns predominated in patients with long duration of ILD (p>0.01). Pure GGO were not observed. Lesion profusion was highly variable and correlated moderately negative with diffusion capacity (mean 88.2% (SD{+-}20.9%); r=-0.54; p<0.001) and very weak with vital capacity and FEV1 (mean values 92.2% (SD{+-}18.3%); r=-0.27; p<0.05 and 89.8% (SD{+-}17.5%); r=-0.31; p<0.01). In patients with GGO, BAL differentials tended towards neutrophilia ({kappa}=0.39; p=0.04; McNemar test p>0.2), but not towards lymphocytosis ({kappa}=0.10; p=0.23; McNemar test p>0.2). Differences in smoking history were not significant (p>0.1). The HRCT appears most appropriate for the detection and follow-up of ILD associated with RA. The PFT and BAL correlate only partially with lesion profusion or grading on HRCT, but they contribute valuable information about dynamic lung function and differential diagnoses (pneumonia, medication side

  6. Clinical factors associated with a Candida albicans Germ Tube Antibody positive test in Intensive Care Unit patients

    Directory of Open Access Journals (Sweden)

    Martín-Mazuelos Estrella

    2011-03-01

    Full Text Available Abstract Background Poor outcomes of invasive candidiasis (IC are associated with the difficulty in establishing the microbiological diagnosis at an early stage. New scores and laboratory tests have been developed in order to make an early therapeutic intervention in an attempt to reduce the high mortality associated with invasive fungal infections. Candida albicans IFA IgG has been recently commercialized for germ tube antibody detection (CAGTA. This test provides a rapid and simple diagnosis of IC (84.4% sensitivity and 94.7% specificity. The aim of this study is to identify the patients who could be benefited by the use of CAGTA test in critical care setting. Methods A prospective, cohort, observational multicentre study was carried out in six medical/surgical Intensive care units (ICU of tertiary-care Spanish hospitals. Candida albicans Germ Tube Antibody test was performed twice a week if predetermined risk factors were present, and serologically demonstrated candidiasis was considered if the testing serum dilution was ≥ 1:160 in at least one sample and no other microbiological evidence of invasive candidiasis was found. Results Fifty-three critically ill non-neutropenic patients (37.7% post surgery were included. Twenty-two patients (41.5% had CAGTA-positive results, none of them with positive blood culture for Candida. Neither corrected colonization index nor antifungal treatment had influence on CAGTA results. This finding could corroborate that the CAGTA may be an important biomarker to distinguish between colonization and infection in these patients. The presence of acute renal failure at the beginning of the study was more frequent in CAGTA-negative patients. Previous surgery was statistically more frequent in CAGTA-positive patients. Conclusions This study identified previous surgery as the principal clinical factor associated with CAGTA-positive results and emphasises the utility of this promising technique, which was not

  7. Lead exposure and the 2010 achievement test scores of children in New York counties

    Directory of Open Access Journals (Sweden)

    Strayhorn Jillian C

    2012-01-01

    Full Text Available Abstract Background Lead is toxic to cognitive and behavioral functioning in children even at levels well below those producing physical symptoms. Continuing efforts in the U.S. since about the 1970s to reduce lead exposure in children have dramatically reduced the incidence of elevated blood lead levels (with elevated levels defined by the current U.S. Centers for Disease Control threshold of 10 μg/dl. The current study examines how much lead toxicity continues to impair the academic achievement of children of New York State, using 2010 test data. Methods This study relies on three sets of data published for the 57 New York counties outside New York City: school achievement data from the New York State Department of Education, data on incidence of elevated blood lead levels from the New York State Department of Health, and data on income from the U.S. Census Bureau. We studied third grade and eighth grade test scores in English Language Arts and mathematics. Using the county as the unit of analysis, we computed bivariate correlations and regression coefficients, with percent of children achieving at the lowest reported level as the dependent variable and the percent of preschoolers in the county with elevated blood lead levels as the independent variable. Then we repeated those analyses using partial correlations to control for possible confounding effects of family income, and using multiple regressions with income included. Results The bivariate correlations between incidence of elevated lead and number of children in the lowest achievement group ranged between 0.38 and 0.47. The partial correlations ranged from 0.29 to 0.40. The regression coefficients, both bivariate and partial (both estimating the increase in percent of children in the lowest achievement group for every percent increase in the children with elevated blood lead levels, ranged from 0.52 to 1.31. All regression coefficients, when rounded to the nearest integer, were

  8. 一种改进的双变量收缩模型图像去噪%An improved image denoising method for bivariate shrinkage model

    Institute of Scientific and Technical Information of China (English)

    李向军; 姜玉莉

    2014-01-01

    An improved image denoising method for local adaptive bivariate shrinkage model is proposed in this paper ac-cording to the characteristics that the low-frequency subband of noise image contains noise. The high-frequency subband is de-noised by locally adaptive bivariate shrinkage model,and the residual low-frequency subband is denoised by locally adaptive Gaussian model. This method can reflect both the clustering performance of intra-scale and the correlation of inter-scale,and has good local adaptive property. The discrete wavelet transform was used to denoise in a experiment. The experimental results show the improved algorithm is more superior to the classical methods in both PSNR and subjective visual effect.%针对噪声图像低频子带含有噪声的特点,给出了一种改进的局部自适应双变量收缩模型的图像去噪算法,对于高频子带用局部自适应双变量模型进行去噪,而对低频子带用具有局部自适应的高斯模型进行去噪。该算法既体现了尺度内的聚类性,又体现了尺度间的相关性且具有很好的局部自适应性,在实验中用离散小波变换进行去噪。实验结果表明,这种改进的算法无论从峰值信噪比,还是从主观视觉效果上都要优于传统的去噪算法。

  9. 二元混合型指数分布的识别性及其应用%Identification of Bivariate Mixed Exponential Distribution and its Applications

    Institute of Scientific and Technical Information of China (English)

    张菁菁; 李国安

    2011-01-01

    对新提出的一类二元混合型指数分布和其他三类二元混合型指数分布,讨论了它们的分布识别问题,即记z=min(x1,x2),I=i,当z=xi;记U-max(&,x2),J=j,当U=Xi;已知(Z,I)或(U,J)的分布,求(X1,X2)分布的唯一性问题.给出了(x1,x2)服从Marshall-Olkin型指数分布时,有关寿险中Z及u的精算现值的2个公式.%Considering a new bivariate mixed exponential distribution and other three kinds of bivariate mixed exponential distribution, the identification of their distributions is presented. Z = min (X1, X2) is first defined, by letting/=/ withZ=X; U=max(X1,X2) is defined. LetJ=jwhileU=Xj, if the distribution of (Z,I) or (U, J)is known, the uniqueness of the distribution of (X1, X2) needs being calculated. In the end, the author puts forth two formulae which are related to the net single premium of Z and U in life insurance, while (X1, X2) obey Marshall-Olkin type's exponential distribution.

  10. Use of the dog as non-rodent test species in the safety testing schedule associated with the registration of crop and plant protection products (pesticides): present status.

    Science.gov (United States)

    Box, Rainer J; Spielmann, Horst

    2005-11-01

    The results from a survey of the expert information that is publicly accessible on the use of the dog as test species during the regulatory evaluation of agricultural chemicals and pesticides are reported. Methods that are being used or considered in order to reduce the number of dogs used for this purpose are described. Regulatory evaluation aims at establishing threshold values for safe human exposure; it is based on no-observed-adverse-effect levels (NOELs) determined in animal studies. Current regulations require testing in two species, a rodent species (usually rat or mouse), and a non-rodent species (usually the dog). Subchronic (90-day) and chronic (12-month) repeated-dose feeding studies must be routinely conducted in dogs. This report first focuses on the results from a retrospective study analysing data on 216 pesticides kept on record by the Bundesinstitut für Risikobewertung, BfR (German Federal Institute for Risk Assessment), the competent regulatory authority in Germany. The study was sponsored and coordinated by SET, the German Foundation for the Promotion of Research on Replacement and Complementary Methods to Reduce Animal Testing (Stiftung zur Förderung der Erforschung von Ersatz-und Ergänzungsmethoden zur Einschränkung von Tierversuchen, Mainz) and conducted by the BfR. Since the data submitted for registration of a product is the property of the manufacturer, the study could only proceed with the collaboration of the German Association of Manufacturers of Agricultural Chemicals (Industrieverband Agrar, IVA). To ensure confidentiality, designated codes were used instead of the compounds' proper names when the study was published. The results support two major conclusions. The use of the dog for the testing of pesticides is indeed necessary because the dog has proved to be the most sensitive species for about 15% of the compounds examined. However, chronic studies are only of limited value since they only provide essential information that

  11. Testing for rational bubbles in a co-explosive vector autoregression

    DEFF Research Database (Denmark)

    Engsted, Tom; Nielsen, Bent

    We derive the parameter restrictions that a standard equity market model implies for a bivariate vector autoregression for stock prices and dividends, and we show how to test these restrictions using likelihood ratio tests. The restrictions, which imply that stock returns are unpredictable...

  12. The effect of Trier Social Stress Test (TSST on item and associative recognition of words and pictures in healthy participants

    Directory of Open Access Journals (Sweden)

    Jonathan eGuez

    2016-04-01

    Full Text Available Psychological stress, induced by the Trier Social Stress Test (TSST, has repeatedly been shown to alter memory performance. Although factors influencing memory performance such as stimulus nature (verbal /pictorial and emotional valence have been extensively studied, results whether stress impairs or improves memory are still inconsistent. This study aimed at exploring the effect of TSST on item versus associative memory for neutral, verbal, and pictorial stimuli. 48 healthy subjects were recruited, 24 participants were randomly assigned to the TSST group and the remaining 24 participants were assigned to the control group. Stress reactivity was measured by psychological (subjective state anxiety ratings and physiological (Galvanic skin response recording measurements. Subjects performed an item-association memory task for both stimulus types (words, pictures simultaneously, before, and after the stress/non-stress manipulation. The results showed that memory recognition for pictorial stimuli was higher than for verbal stimuli. Memory for both words and pictures was impaired following TSST; while the source for this impairment was specific to associative recognition in pictures, a more general deficit was observed for verbal material, as expressed in decreased recognition for both items and associations following TSST. Response latency analysis indicated that the TSST manipulation decreased response time but at the cost of memory accuracy. We conclude that stress does not uniformly affect memory; rather it interacts with the task’s cognitive load and stimulus type. Applying the current study results to patients diagnosed with disorders associated with traumatic stress, our findings in healthy subjects under acute stress provide further support for our assertion that patients’ impaired memory originates in poor recollection processing following depletion of attentional resources.

  13. Accuracy of serum uric acid as a predictive test for maternal complications in pre-eclampsia: Bivariate meta-analysis and decision analysis

    NARCIS (Netherlands)

    C.M. Koopmans; M.G. van Pampus; H. Groen; J.G. Aarnoudse; P.P. van den Berg; B.W.J. Mol

    2009-01-01

    The aim of this study is to determine the accuracy and clinical value of serum uric acid in predicting maternal complications in women with pre-eclampsia. An existing meta-analysis on the subject was updated. The accuracy of serum uric acid for the prediction of maternal complications was assessed w

  14. Accuracy of serum uric acid as a predictive test for maternal complications in pre-eclampsia : Bivariate meta-analysis and decision analysis

    NARCIS (Netherlands)

    Koopmans, C.M.; van Pampus, Maria; Groen, H.; Aarnoudse, J.G.; van den Berg, P.P.; Mol, B.W.J.

    2009-01-01

    The aim of this study is to determine the accuracy and clinical value of serum uric acid in predicting maternal complications in women with pre-eclampsia. An existing meta-analysis on the subject was updated. The accuracy of serum uric acid for the prediction of maternal complications was assessed w

  15. Between-Seasons Test-Retest Reliability of Clinically Measured Reaction Time in National Collegiate Athletic Association Division I Athletes

    Science.gov (United States)

    Eckner, James T.; Kutcher, Jeffrey S.; Richardson, James K.

    2011-01-01

    Context: Reaction time is typically impaired after concussion. A clinical test of reaction time (RTclin) that does not require a computer to administer may be a valuable tool to assist in concussion diagnosis and management. Objective: To determine the test-retest reliability of RTclin measured over successive seasons in competitive collegiate athletes and to compare these results with a computerized measure of reaction time (RTcomp). Design: Case series with repeated measures. Setting: Preparticipation physical examinations for the football, women's soccer, and wrestling teams at a single university. Patients or Other Participants: 102 National Collegiate Athletic Association Division I athletes. Interventions : The RTclin was measured using a measuring stick embedded in a weighted rubber disk that was released and caught as quickly as possible. The RTcomp was measured using the simple reaction time component of CogState Sport. Main Outcome Measure(s): Data were collected at 2 time points, 1 season apart, during preparticipation physical examinations. Outcomes were mean simple RTclin and RTcomp. Results: The intraclass correlation coefficient estimates from season 1 to season 2 were 0.645 for RTclin (n = 102, entire sample) and 0.512 for RTcomp (n = 62 athletes who had 2 consecutive valid baseline CogState Sport test sessions). Conclusions: The test-retest reliability of RTclin over consecutive seasons compared favorably with that of a concurrently tested computerized measure of reaction time and with literature-based estimates of computerized reaction time measures. This finding supports the potential use of RTclin as part of a multifaceted concussion assessment battery. Further prospective study is warranted. PMID:21944073

  16. Porcine E. coli: virulence-associated genes, resistance genes and adhesion and probiotic activity tested by a new screening method.

    Science.gov (United States)

    Schierack, Peter; Rödiger, Stefan; Kuhl, Christoph; Hiemann, Rico; Roggenbuck, Dirk; Li, Ganwu; Weinreich, Jörg; Berger, Enrico; Nolan, Lisa K; Nicholson, Bryon; Römer, Antje; Frömmel, Ulrike; Wieler, Lothar H; Schröder, Christian

    2013-01-01

    We established an automated screening method to characterize adhesion of Escherichia coli to intestinal porcine epithelial cells (IPEC-J2) and their probiotic activity against infection by enteropathogenic E. coli (EPEC). 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars. Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coli isolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity than E. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation. In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars.

  17. Porcine E. coli: virulence-associated genes, resistance genes and adhesion and probiotic activity tested by a new screening method.

    Directory of Open Access Journals (Sweden)

    Peter Schierack

    Full Text Available We established an automated screening method to characterize adhesion of Escherichia coli to intestinal porcine epithelial cells (IPEC-J2 and their probiotic activity against infection by enteropathogenic E. coli (EPEC. 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars. Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coli isolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity than E. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation. In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars.

  18. Errors on the Trail Making Test Are Associated with Right Hemispheric Frontal Lobe Damage in Stroke Patients

    Directory of Open Access Journals (Sweden)

    Bruno Kopp

    2015-01-01

    Full Text Available Measures of performance on the Trail Making Test (TMT are among the most popular neuropsychological assessment techniques. Completion time on TMT-A is considered to provide a measure of processing speed, whereas completion time on TMT-B is considered to constitute a behavioral measure of the ability to shift between cognitive sets (cognitive flexibility, commonly attributed to the frontal lobes. However, empirical evidence linking performance on the TMT-B to localized frontal lesions is mostly lacking. Here, we examined the association of frontal lesions following stroke with TMT-B performance measures (i.e., completion time and completion accuracy measures using voxel-based lesion-behavior mapping, with a focus on right hemispheric frontal lobe lesions. Our results suggest that the number of errors, but not completion time on the TMT-B, is associated with right hemispheric frontal lesions. This finding contradicts common clinical practice—the use of completion time on the TMT-B to measure cognitive flexibility, and it underscores the need for additional research on the association between cognitive flexibility and the frontal lobes. Further work in a larger sample, including left frontal lobe damage and with more power to detect effects of right posterior brain injury, is necessary to determine whether our observation is specific for right frontal lesions.

  19. [Consensus for antimicrobial susceptibility testing for Enterobacteriaceae. Subcommittee on Antimicrobials, SADEBAC (Argentinian Society of Clinical Bacteriology), Argentinian Association of Microbiology].

    Science.gov (United States)

    Famiglietti, A; Quinteros, M; Vázquez, M; Marín, M; Nicola, F; Radice, M; Galas, M; Pasterán, F; Bantar, C; Casellas, J M; Kovensky Pupko, J; Couto, E; Goldberg, M; Lopardo, H; Gutkind, G; Soloaga, R

    2005-01-01

    Taking into account previous recommendations from the National Committee for Clinical Laboratory Standards (NCCLS), the Antimicrobial Committee, Sociedad Argentina de Bacteriología Clínica (SADEBAC), Asociación Argentina de Microbiología (AAM), and the experience from its members and some invited microbiologists, a consensus was obtained for antimicrobial susceptibility testing and interpretation in most frequent enterobacterial species isolated from clinical samples in our region. This document describes the natural antimicrobial resistance of some Enterobacteriaceae family members, including the resistance profiles due to their own chromosomal encoded beta-lactamases. A list of the antimicrobial agents that should be tested, their position on the agar plates, in order to detect the most frequent antimicrobial resistance mechanisms, and considerations on which antimicrobial agents should be reported regarding to the infection site and patient characteristics are included. Also, a description on appropriate phenotypic screening and confirmatory test for detection of prevalent extended spectrum beta-lactamases in our region are presented. Finally, a summary on frequent antimicrobial susceptibility profiles and their probably associated resistance mechanisms, and some infrequent antimicrobial resistance profiles that deserve confirmation are outlined.

  20. Testing the thrifty gene hypothesis: the Gly482Ser variant in PPARGC1A is associated with BMI in Tongans

    Directory of Open Access Journals (Sweden)

    Macartney-Coxson Donia P

    2011-01-01

    Full Text Available Abstract Background The thrifty gene hypothesis posits that, in populations that experienced periods of feast and famine, natural selection favoured individuals carrying thrifty alleles that promote the storage of fat and energy. Polynesians likely experienced long periods of cold stress and starvation during their settlement of the Pacific and today have high rates of obesity and type 2 diabetes (T2DM, possibly due to past positive selection for thrifty alleles. Alternatively, T2DM risk alleles may simply have drifted to high frequency in Polynesians. To identify thrifty alleles in Polynesians, we previously examined evidence of positive selection on T2DM-associated SNPs and identified a T2DM risk allele at unusually high frequency in Polynesians. We suggested that the risk allele of the Gly482Ser variant in the PPARGC1A gene was driven to high frequency in Polynesians by positive selection and therefore possibly represented a thrifty allele in the Pacific. Methods Here we examine whether PPARGC1A is a thrifty gene in Pacific populations by testing for an association between Gly482Ser genotypes and BMI in two Pacific populations (Maori and Tongans and by evaluating the frequency of the risk allele of the Gly482Ser variant in a sample of worldwide populations. Results We find that the Gly482Ser variant is associated with BMI in Tongans but not in Maori. In a sample of 58 populations worldwide, we also show that the 482Ser risk allele reaches its highest frequency in the Pacific. Conclusion The association between Gly482Ser genotypes and BMI in Tongans together with the worldwide frequency distribution of the Gly482Ser risk allele suggests that PPARGC1A remains a candidate thrifty gene in Pacific populations.

  1. Pilot Evaluation of a Novel Clinical Test of Reaction Time in National Collegiate Athletic Association Division I Football Players

    Science.gov (United States)

    Eckner, James T.; Kutcher, Jeffrey S.; Richardson, James K.

    2010-01-01

    Abstract Context: Evidence suggests that concussion prolongs reaction time (RT). We have developed a simple, reliable clinical tool for measuring reaction time that may be of value in the assessment of concussion in athletes. Objective: To compare baseline values of clinical RT (RTclin) obtained using the new clinical reaction time apparatus with computerized RT (RTcomp) obtained using a validated computerized neuropsychological test battery. Design: Cross-sectional study. Setting: Data were collected during a National Collegiate Athletic Association Division I collegiate football team's preparticipation physical examination session. Patients or Other Participants: Ninety-four Division I collegiate football players. Main Outcome Measure(s): The RTclin was measured using a 1.3-m measuring stick embedded in a weighted rubber disk that was released and caught as quickly as possible. The RTcomp was measured using the simple RT component of CogState Sport. Results: For the 68 athletes whose CogState Sport tests passed the program's integrity check, RTclin and RTcomp were correlated (r  =  0.445, P < .001). Overall, mean RTclin was shorter and less variable than mean RTcomp (203 ± 20 milliseconds versus 268 ± 44 milliseconds; P < .001). When RTclin and RTcomp were compared between those athletes with (n  =  68) and those without (n  =  26) valid CogState Sport test sessions, mean RTclin was similar (202 ± 19 milliseconds versus 207 ± 23 milliseconds; P  =  .390), but mean RTcomp was different (258 ± 35 milliseconds versus 290 ± 55 milliseconds; P  =  .009). Conclusions: The RTclin was positively correlated with RTcomp and yielded more consistent reaction time values during baseline testing. Given that RTclin is easy to measure using simple, inexpensive equipment, further prospective study is warranted to determine its clinical utility in the assessment of concussion in athletes. PMID:20617905

  2. Pump and probe damage testing for investigation of transient material modifications associated with laser damage in optical materials

    Energy Technology Data Exchange (ETDEWEB)

    Negres, R A; Feit, M D; DeMange, P; Bude, J D; Demos, S G

    2007-10-18

    Laser-induced breakdown in the bulk of transparent dielectric materials is associated with the generation of extreme localized conditions of temperatures and pressures. In this work, we perform pump and probe damage testing experiments to investigate the evolution of transient absorption by the host material arising from modifications following confined laser energy deposition in fused silica and DKDP materials. Specifically, we measure the size of the damage sites observed in the region of spatial overlap between the pump and probe pulses versus probe time delay and energy. Results of this proof-of-principle experimental work confirm that material modifications under extreme conditions created during a damage event include transient optical absorption. In addition, we found that the relaxation times of the induced absorption are very distinct for DKDP and SiO{sub 2} even under identical excitation conditions, on the order of 100 ns and 100 {micro}s, respectively.

  3. Testing the Disk-locking Paradigm: An Association between U - V Excess and Rotation in NGC 2264

    Science.gov (United States)

    Fallscheer, Cassandra; Herbst, William

    2006-08-01

    We present some results from a UVI photometric study of a field in the young open cluster NGC 2264 that is aimed, in part, at testing whether accretion in pre-main-sequence stars is linked to rotation. We confirm that U-V excess is well correlated with the Hα equivalent width for the stars in our sample. We show that for the more massive stars in the cluster sample (roughly 0.4-1.2 Msolar), there is also a significant association between U-V excess and rotation, in the sense that slow rotators are more likely to show excess U-band emission and variability. This constitutes significant new evidence in support of the disk-locking paradigm.

  4. Testing the Disk-Locking Paradigm: An Association Between U-V Excess and Rotation in NGC 2264

    CERN Document Server

    Fallscheer, C; Fallscheer, Cassandra; Herbst, William

    2006-01-01

    We present some results from a UVI photometric study of a field in the young open cluster NGC 2264 aimed, in part, at testing whether accretion in pre-main sequence stars is linked to rotation. We confirm that U-V excess is well correlated with H-alpha equivalent width for the stars in our sample. We show that for the more massive stars in the cluster sample (roughly 0.4-1.2 M_sun) there is also a significant association between U-V excess and rotation, in the sense that slow rotators are more likely to show excess U-band emission and variability. This constitutes significant new evidence in support of the disk-locking paradigm.

  5. Preoperative hypoalgesia after cold pressor test and aerobic exercise is associated with pain relief six months after total knee replacement

    DEFF Research Database (Denmark)

    Vaegter, Henrik Bjarke; Handberg, Gitte; Emmeluth, Claus

    2017-01-01

    PPT) and subsequently the pain tolerance threshold (cPTT). 2) Manual pressure pain thresholds (PPTs) at the legs, arm and shoulder. Clinical pain intensity (numerical rating scale) and psychological distress (questionnaires) were assessed. RESULTS: Clinical pain intensity, psychological distress, cPPT and PPT...... investigated the association between exercise-induced hypoalgesia (EIH) and CPM on post-TKR pain relief. METHODS: Before and six months post-TKR, 14 patients with chronic knee osteoarthritis performed the cold pressor test on the non-affected leg and two exercise conditions (bicycling and isometric knee...... post-TKR (Passociated with pain relief six months after TKR. EIH as a novel preoperative screening tool should be further investigated...

  6. Association of macroscopic laboratory testing and micromechanics modelling for the evaluation of the poroelastic parameters of a hardened cement paste

    CERN Document Server

    Ghabezloo, Siavash

    2010-01-01

    The results of a macro-scale experimental study performed on a hardened class G cement paste [Ghabezloo et al. (2008) Cem. Con. Res. (38) 1424-1437] are used in association with the micromechanics modelling and homogenization technique for evaluation of the complete set of poroelastic parameters of the material. The experimental study consisted in drained, undrained and unjacketed isotropic compression tests. Analysis of the experimental results revealed that the active porosity of the studied cement paste is smaller than its total porosity. A multi-scale homogenization model, calibrated on the experimental results, is used to extrapolate the poroelastic parameters to cement pastes prepared with different water-to-cement ratio. The notion of cement paste active porosity is discussed and the poroelastic parameters of hardened cement paste for an ideal, perfectly drained condition are evaluated using the homogenization model.

  7. Prevalence of Syphilis and associated factors in homeless people of Sao Paulo, Brazil, using a Rapid Test

    Directory of Open Access Journals (Sweden)

    Valdir Monteiro Pinto

    2014-06-01

    Full Text Available Introduction: Homeless people are a vulnerable group to sexually transmitted diseases (STD with high prevalence of syphilis and hepatitis. Objectives: To estimate the prevalence of syphilis infection and its association with risky behaviors for STDs in a sample of homeless people, and to assess the feasibility of the use of rapid syphilis test (RST in this population. Methods: Cross-sectional study, in a convenience sample of homeless people assisted in social support services of São Paulo, between 2006 and 2007. A structured questionnaire was applied and RST was performed. In addition, a blood sample for syphilis detection was also collected. The sensitivity and specificity of the RST was estimated using conventional laboratory diagnosis (VDRL + TPHA as reference. Results: 1,405 volunteers were included in the study. The prevalence rate of syphilis was 7.0%, and was associated with homosexual practices (ORadj 4.9; 95%CI 2.6 - 9.4, prior history of STD (ORadj 2.6; 95%CI 1.7 - 4.0 and with self-referred non-white race (ORadj 1.9; 95%CI 1.1 - 3.4. The sensitivity and specificity of the RST for syphilis were, respectively, 81.4 and 92.1%. Conclusion: The high prevalence of syphilis infection among homeless people shows the need for actions for its control and the utilization of RST that can be considered an efficient strategy due to its sensitivity and specificity. Public Health policymakers must strengthen actions for syphilis control, with screening tests for syphilis and early treatment, decreasing morbidity with the improvement of sexual and reproductive health of the population in general and especially the most vulnerable.

  8. Some Improved Estimators of Co-efficient of Variation from Bi-variate normal distribution: A Monte Carlo Comparison

    OpenAIRE

    Archana V; Aruna Rao K

    2014-01-01

    Co-efficient of variation is a unitless measure of dispersion and is very frequently used in scientific investigations. This has motivated several researchers to propose estimators and tests concerning the co-efficient of variation of normal distribution(s). While proposing a class of estimators for the co-efficient of variation of a finite population, Tripathi et al., (2002) suggested that the estimator of co-efficient of variation of a finite population can also be used as an estimator of C...

  9. Angina pectoris during daily activities and exercise stress testing: The role of inducible myocardial ischemia and psychological distress.

    Science.gov (United States)

    Sullivan, Mark D; Ciechanowski, Paul S; Russo, Joan E; Spertus, John A; Soine, Laurie A; Jordan-Keith, Kier; Caldwell, James H

    2008-10-31

    Physicians often consider angina pectoris to be synonymous with myocardial ischemia. However, the relationship between angina and myocardial ischemia is highly variable and we have little insight into the sources of this variability. We investigated the relationship of inducible myocardial ischemia on SPECT stress perfusion imaging to angina reported with routine daily activities during the previous four weeks (N=788) and to angina reported during an exercise stress test (N=371) in individuals with confirmed or suspected coronary disease referred for clinical testing. We found that angina experienced during daily life is more strongly and consistently associated with psychological distress and the personal threat associated with angina than with inducible myocardial ischemia. In multivariable models, the presence of any angina during routine activities over the prior month was significantly associated with age, perceived risk of myocardial infarction, and anxiety when compared to those with no reported angina in the past month. Angina during daily life was not significantly associated with inducible myocardial ischemia on stress perfusion imaging in bivariate or multivariable models. In contrast, angina experienced during exercise stress testing was significantly related to image and ECG ischemia, though it was also significantly associated with anxiety. These results suggest that angina frequency over the previous four weeks is more strongly associated with personal threat and psychosocial distress than with inducible myocardial ischemia. These results lend support to angina treatment strategies that aim to reduce threat and distress as well as to reduce myocardial ischemia.

  10. Arms Control and nonproliferation technologies: Technology options and associated measures for monitoring a Comprehensive Test Ban, Second quarter

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Leslie A.

    1994-01-01

    This newsletter contains reprinted papers discussing technology options and associated measures for monitoring a Comprehensive Test Ban Treaty (CTBT). These papers were presented to the Conference on Disarmament (CD) in May and June 1994. An interagency Verification Monitoring Task Force developed the papers. The task force included participants from the Arms Control and Disarmament Agency, the Department of Defense, the Department of Energy, the Intelligence Community, the Department of Interior, and the Department of State. The purpose of this edition of Arms Control and Nonproliferation Technologies is to share these papers with the broad base of stakeholders in a CTBT and to facilitate future technology discussions. The papers in the first group discuss possible technology options for monitoring a CTBT in all environments (underground, underwater, atmosphere, and space). These technologies, along with on-site inspections, would facilitate CTBT monitoring by treaty participants. The papers in the second group present possible associated measures, e.g., information exchanges and transparency measures, that would build confidence among states participating in a CTBT.

  11. Determining student teachers' perceptions on using technology via Likert scale, visual association test and metaphors: A mixed study

    Directory of Open Access Journals (Sweden)

    Mevhibe Kobak

    2013-04-01

    Full Text Available The aim of this study is to determine senior student teachers’ perceptions on using technology by approaching various points of view. In this study, researchers collected data through Technology Perceptions Scale, Visual Association Activity and Technology Metaphors. The participants of the study were 104 senior student teachers who were enrolled in Balıkesir University Necatibey Faculty of Education. In this descriptive study, researchers interpreted qualitative data in conjunction with quantitative data. Based on the data obtained, even though student teachers’ perceptions on using technology were found positive in the light of Likert scale, there was no significant relation in terms of gender and enrolled undergraduate program. According to the results of visual association test, student teachers ranked smartboard, Internet and computer in the first three, and portable media player, mobile phone and video/camera in the last three. Besides, researchers analyzed and classified student teachers’ metaphors about technology under 9 categories: 1developing-changing technology, 2rapidly progressing technology, 3 limitless-endless technology, 4beneficial technology, 5harmful technology, 6both beneficial and harmful technology, 7indispensible technology, 8technology as a necessity, 9 all-inclusive technology. At the end of the study, those nine categories which were acquired using the content analysis technique are presented in a table which shows the interaction between categories in a holistic view.

  12. Colonization with nontuberculous mycobacteria is associated with positive tuberculin skin test reactions in the common marmoset (Callithrix jacchus).

    Science.gov (United States)

    Wachtman, Lynn M; Miller, Andrew D; Xia, DongLing; Curran, Elizabeth H; Mansfield, Keith G

    2011-06-01

    Mycobacterium tuberculosis infections can result in significant morbidity and mortality in nonhuman primate colonies. Preventative health programs designed to detect infection routinely include tuberculin skin testing (TST). Because Mammalian Old Tuberculin used for TST contains antigens common to a variety of mycobacterial species, false-positive results can occur in animals sensitized to nontuberculous mycobacteria (NTM). Over 11 mo, a large colony of common marmosets (Callithrix jacchus) demonstrated a 3.6% prevalence of equivocal or positive TST reactions (termed 'suspect reactions'). Culture of gastric aspirates, bronchoalveolar lavage fluid, and feces revealed a single animal with a positive fecal culture for Mycobacterium gordonae. PCR amplification of M. gordonae DNA in feces collected from animals with suspect TST reactions (demonstrating a 66.7% colonization rate) and colony controls (demonstrating a 14.3% colonization rate) revealed a significant association between suspect TST reactions and intestinal colonization. Gross and histopathologic evaluation revealed a multifocal lymphadenopathy and granulomatous lymphadenitis in 2 of 4 TST-positive marmosets examined. Counter to expectations, granulomatous lymphoid tissue was culture-positive for M. kansasii rather than M. gordonae. Detection of M. gordonae in the feces of TST-suspect animals likely represents an apathogenic intestinal colonization that may serve as an indicator of NTM exposure, whereas evidence of histopathologic disease is associated with the more pathogenic M. kansasii. Although a high index of suspicion for M. tuberculosis should always be maintained, colonization with NTM organisms represents a cause of suspect TST reactions in common marmosets.

  13. Meta-analysis of diagnostic tests accounting for disease prevalence: a new model using trivariate copulas.

    Science.gov (United States)

    Hoyer, A; Kuss, O

    2015-05-20

    In real life and somewhat contrary to biostatistical textbook knowledge, sensitivity and specificity (and not only predictive values) of diagnostic tests can vary with the underlying prevalence of disease. In meta-analysis of diagnostic studies, accounting for this fact naturally leads to a trivariate expansion of the traditional bivariate logistic regression model with random study effects. In this paper, a new model is proposed using trivariate copulas and beta-binomial marginal distributions for sensitivity, specificity, and prevalence as an expansion of the bivariate model. Two different copulas are used, the trivariate Gaussian copula and a trivariate vine copula based on the bivariate Plackett copula. This model has a closed-form likelihood, so standard software (e.g., SAS PROC NLMIXED) can be used. The results of a simulation study have shown that the copula models perform at least as good but frequently better than the standard model. The methods are illustrated by two examples.

  14. Neuroticism explains unwanted variance in Implicit Association Tests of personality: Possible evidence for an affective valence confound

    Directory of Open Access Journals (Sweden)

    Monika eFleischhauer

    2013-09-01

    Full Text Available Meta-analytic data highlight the value of the Implicit Association Test (IAT as an indirect measure of personality. Based on evidence suggesting that confounding factors such as cognitive abilities contribute to the IAT effect, this study provides a first investigation of whether basic personality traits explain unwanted variance in the IAT. In a gender-balanced sample of 204 volunteers, the Big-Five dimensions were assessed via self-report, peer-report, and IAT. By means of structural equation modeling, latent Big-Five personality factors (based on self- and peer-report were estimated and their predictive value for unwanted variance in the IAT was examined. In a first analysis, unwanted variance was defined in the sense of method-specific variance which may result from differences in task demands between the two IAT block conditions and which can be mirrored by the absolute size of the IAT effects. In a second analysis, unwanted variance was examined in a broader sense defined as those systematic variance components in the raw IAT scores that are not explained by the latent implicit personality factors. In contrast to the absolute IAT scores, this also considers biases associated with the direction of IAT effects (i.e., whether they are positive or negative in sign, biases that might result, for example, from the IAT’s stimulus or category features. None of the explicit Big-Five factors was predictive for method-specific variance in the IATs (first analysis. However, when considering unwanted variance that goes beyond pure method-specific variance (second analysis, a substantial effect of neuroticism occurred that may have been driven by the affective valence of IAT attribute categories and the facilitated processing of negative stimuli, typically associated with neuroticism. The findings thus point to the necessity of using attribute category labels and stimuli of similar affective valence in personality IATs to avoid confounding due to

  15. 基于噪声辅助非均匀采样复数据经验模态分解的混沌信号降噪%A chaotic signal denoising metho d develop ed on the basis of noise-assisted nonuniformly sampled bivariate empirical mo de decomp osition

    Institute of Scientific and Technical Information of China (English)

    王小飞; 曲建岭; 高峰; 周玉平; 张翔宇

    2014-01-01

    鉴于非均匀采样复数据经验模态分解(NSBEMD)相对传统分解方法的优势和噪声的NSBEMD特性,提出了一种基于噪声辅助NSBEMD的混沌信号自适应降噪方法。该方法首先以含噪混沌信号和高斯白噪声分别为实、虚部来构造复数据并进行NSBEMD,然后根据虚部各IMF的能量来估算实部各IMF中包含的噪声能量,最后根据噪声能量的估计值对实部IMF进行奇异值分解(SVD)降噪。噪声估计实验验证了噪声能量估计方法的可行性,而Lorenz信号和太阳黑子月平均数的降噪实验则表明,相对于现有EMD降噪方法,本文方法能够进一步消除噪声,更清晰地恢复出混沌吸引子的拓扑结构。%According to the advantages of nonuniformly sampled bivariate empirical mode decomposition and the characteris-tics of noise after it, an adaptive chaotic signal denoising method is proposed based on the noise-assisted nonuniformly sampled bivariate empirical mode decomposition. Firstly, a complex signal is constructed for the noise-assisted nonuni-formly sampled bivariate empirical mode decomposition, by using noisy chaotic signal and gaussian white noise as the real part and imaginary part respectively; secondly, the noise energy of each intrinsic mode function in the real part is estimated according to the energy of each intrinsic mode function in the imaginary part; and finally, from the above results, each intrinsic mode function in the real part is denoised by using the singular value decomposition. Noise en-ergy estimate numerical experiment validates the feasibility of this method, and the denoising tests for Lorenz signal and monthly sunspot data indicate that our method shows advantages in both noise reduction and chaotic attractor topological configuration reversion.

  16. Multidrug-Resistant Tuberculosis and Its Association with Adrenal Insufficiency: Assessment with the Low-Dose ACTH Stimulation Test

    Science.gov (United States)

    Rodríguez-Gutiérrez, René; Rendon, Adrian; Barrera-Sánchez, Maximiliano; Carlos-Reyna, Kevin Erick Gabriel; Álvarez-Villalobos, Neri Alejandro; González-Saldivar, Gloria; González-González, José Gerardo

    2016-01-01

    Background. Multidrug-resistant tuberculosis (MDR-TB) is a major public health care concern that affects the life of millions of people around the world. The association of tuberculosis and adrenal insufficiency is well known; however, it is thought to be less prevalent every time. A spike in TB incidence and a lack of evidence of this association in patients with MDR-TB call for reassessment of an illness (adrenal dysfunction) that if not diagnosed could seriously jeopardize patients' health. Objective. To determine the prevalence of adrenocortical insufficiency in patients with MDR-TB using the low-dose (1 μg) ACTH stimulation test at baseline and at 6–12 months of follow-up after antituberculosis treatment and culture conversion. Methods. A total of 48 men or women, aged ≥18 years (HIV-negative patients diagnosed with pulmonary MDR-TB) were included in this prospective observational study. Blood samples for serum cortisol were taken at baseline and 30 and 60 minutes after 1 μg ACTH stimulation at our tertiary level university hospital before and after antituberculosis treatment. Results. Forty-seven percent of subjects had primary MDR-TB; 43.8% had type 2 diabetes; none were HIV-positive. We found at enrollment 2 cases (4.2%) of adrenal insufficiency taking 500 nmol/L as the standard cutoff point value and 4 cases (8.3%) alternatively, using 550 nmol/L. After antituberculosis intensive phase drug-treatment and a negative mycobacterial culture (10.2 ± 3.6 months) adrenocortical function was restored in all cases. Conclusions. In patients with MDR-TB, using the low-dose ACTH stimulation test, a low prevalence of mild adrenal insufficiency was observed. After antituberculosis treatment adrenal function was restored in all cases. Given the increasing and worrying epidemic of MDR-TB these findings have important clinical implications that may help clinicians and patients make better decisions when deciding to test for adrenocortical dysfunction or

  17. Multidrug-Resistant Tuberculosis and Its Association with Adrenal Insufficiency: Assessment with the Low-Dose ACTH Stimulation Test

    Directory of Open Access Journals (Sweden)

    René Rodríguez-Gutiérrez

    2016-01-01

    Full Text Available Background. Multidrug-resistant tuberculosis (MDR-TB is a major public health care concern that affects the life of millions of people around the world. The association of tuberculosis and adrenal insufficiency is well known; however, it is thought to be less prevalent every time. A spike in TB incidence and a lack of evidence of this association in patients with MDR-TB call for reassessment of an illness (adrenal dysfunction that if not diagnosed could seriously jeopardize patients’ health. Objective. To determine the prevalence of adrenocortical insufficiency in patients with MDR-TB using the low-dose (1 μg ACTH stimulation test at baseline and at 6–12 months of follow-up after antituberculosis treatment and culture conversion. Methods. A total of 48 men or women, aged ≥18 years (HIV-negative patients diagnosed with pulmonary MDR-TB were included in this prospective observational study. Blood samples for serum cortisol were taken at baseline and 30 and 60 minutes after 1 μg ACTH stimulation at our tertiary level university hospital before and after antituberculosis treatment. Results. Forty-seven percent of subjects had primary MDR-TB; 43.8% had type 2 diabetes; none were HIV-positive. We found at enrollment 2 cases (4.2% of adrenal insufficiency taking 500 nmol/L as the standard cutoff point value and 4 cases (8.3% alternatively, using 550 nmol/L. After antituberculosis intensive phase drug-treatment and a negative mycobacterial culture (10.2±3.6 months adrenocortical function was restored in all cases. Conclusions. In patients with MDR-TB, using the low-dose ACTH stimulation test, a low prevalence of mild adrenal insufficiency was observed. After antituberculosis treatment adrenal function was restored in all cases. Given the increasing and worrying epidemic of MDR-TB these findings have important clinical implications that may help clinicians and patients make better decisions when deciding to test for adrenocortical

  18. [Prenatal care and risk factors associated with premature birth and low birth weight in the a capital in the Brazilian Northeast].

    Science.gov (United States)

    Gonzaga, Isabel Clarisse Albuquerque; Santos, Sheila Lima Diogenes; Silva, Ana Roberta Vilarouca da; Campelo, Viriato

    2016-06-01

    The main determinants of the risk of mortality in the neonatal period are low birth weight and premature birth. The study sought to analyze the adequacy of prenatal care and risk factors associated with premature birth and low birth weight in a northeastern Brazilian capital. This is a case-control study. A model for adequacy of prenatal conditions composed of four indicators was created. Descriptive statistics for univariate analysis were used; as well as Wald linear trend tests, Student's t and chi-square test for bivariate analysis and multiple logistic regression for multivariate analysis with p adequacy of prenatal care, variable indicator III remained significant, showing that mothers who had inadequate prenatal care had an increased chance for the occurrence of the outcome, highlighting the need for adequate public health policies of care for pregnant women in the municipality under scrutiny.

  19. Perception of Genetic Testing for Deafness and Factors Associated with Interest in Genetic Testing Among Deaf People in a Selected Population in Sub-Saharan Africa.

    Science.gov (United States)

    Adedokun, Babatunde O; Yusuf, Bidemi O; Lasisi, J Taye; Jinadu, A A; Sunmonu, M T; Ashanke, A F; Lasisi, O Akeem

    2015-12-01

    Understanding the perceptions of genetic testing by members of the deaf community may help in planning deafness genetics research, especially so in the context of strong adherence to cultural values as found among native Africans. Among Yorubas in Nigeria, deafness is perceived to be caused by some offensive actions of the mother during pregnancy, spiritual attack, and childhood infections. We studied attitudes towards, and acceptance of genetic testing by the deaf community in Nigeria. Structured questionnaires were administered to individuals sampled from the Vocational Training Centre for the Deaf, the religious Community, and government schools, among others. The main survey items elicited information about the community in which the deaf people participate, their awareness of genetic testing, whether or not they view genetic testing as acceptable, and their understanding of the purpose of genetic testing. There were 150 deaf participants (61.3 % males, 38.7 % females) with mean age of 26.7 years ±9.8. A majority of survey respondents indicated they relate only with other members of the deaf community (78 %) and reported believing genetic testing does more good than harm (79.3 %); 57 % expressed interest in genetic testing. Interest in genetic testing for deafness or in genetic testing in pregnancy was not related to whether respondents relate primarily to the deaf or to the hearing community. However, a significantly higher number of male respondents and respondents with low education reported interest in genetic testing.

  20. Examining the Role of Social Relationships in the Association between Neuroticism and Test Anxiety--Results from a Study with German Secondary School Students

    Science.gov (United States)

    Hoferichter, Frances; Raufelder, Diana

    2015-01-01

    The current study investigates the mediating role of student-student relationships (SSRs) and teacher-student relationships (TSRs) in the association between neuroticism and test anxiety. Gender differences in these associations were examined. A total of 513 adolescent girls and boys from secondary schools in Berlin, Germany completed…

  1. Association of skin test reactivity, specific IgE, total IgE, and eosinophils with nasal symptoms in a community-based population study

    NARCIS (Netherlands)

    Droste, JHJ; Kerkhof, M; deMonchy, JGR; Schouten, JP; Rijcken, B

    1996-01-01

    Background: Skin prick tests and measurement of specific IgE are important markers possible allergic causes of disorders of the upper respiratory tract. Objective: In this study we investigated the association of skin test reactivity and specific IgE positivity to five common aeroallergens separatel

  2. Associations of the stair climb power test with muscle strength and functional performance in people with COPD: A cross-sectional study

    DEFF Research Database (Denmark)

    Roig, Marc; Eng, Janice J.; MacIntyre, Donna L.;

    2010-01-01

    BACKGROUND: The Stair Climb Power Test (SCPT) is a functional test associated with leg muscle power in older people. OBJECTIVE: The purposes of this study were to compare the results of the SCPT in people with chronic obstructive pulmonary disease (COPD) and people who were healthy and to explore...

  3. Possible Risk Factors Associated with Mastitis in Indigenous Cattle in Punjab, Pakistan

    Directory of Open Access Journals (Sweden)

    Riaz Hussain§, Ahrar Khan*, M. Tariq Javed and Farzana Rizvi

    2012-10-01

    Full Text Available The present study was conducted on 453 lactating cattle of various breed present at 21 farms. The milk samples from these animals were collected to diagnose mastitis using California Mastitis Test (CMT. The epidemiological data related to animals and management was collected and analyzed to draw conclusions. The results of t-test revealed significant association between body weight, udder depth, and lower teat end to floor distance (P<0.01 with mastitis. The bivariate frequency analysis revealed significant association for lactation stage (P<0.0001, teat end to floor distance, parity, udder shape, teat shape, live body weight, teat and/or udder pathology, use of oxytocin, feeding system and milk leakage with mastitis. The results of logistic regression analysis revealed significant negative association between teat length, frequency of culling and number of attendants, while positive association between mastitis teat involved, teat diameter (apex, mid and base, milk leakage, udder shape, pendulous udder, feeding system, udder depth, teat shape, calf suckling, milk yield, teat and/or udder pathology and live body weight. From the results of present it can be concluded that some risk factors were strongly associated with mastitis in cattle.

  4. Gene selection and cancer type classification of diffuse large-B-cell lymphoma using a bivariate mixture model for two-species data.

    Science.gov (United States)

    Su, Yuhua; Nielsen, Dahlia; Zhu, Lei; Richards, Kristy; Suter, Steven; Breen, Matthew; Motsinger-Reif, Alison; Osborne, Jason

    2013-01-05

    : A bivariate mixture model utilizing information across two species was proposed to solve the fundamental problem of identifying differentially expressed genes in microarray experiments. The model utility was illustrated using a dog and human lymphoma data set prepared by a group of scientists in the College of Veterinary Medicine at North Carolina State University. A small number of genes were identified as being differentially expressed in both species and the human genes in this cluster serve as a good predictor for classifying diffuse large-B-cell lymphoma (DLBCL) patients into two subgroups, the germinal center B-cell-like diffuse large B-cell lymphoma and the activated B-cell-like diffuse large B-cell lymphoma. The number of human genes that were observed to be significantly differentially expressed (21) from the two-species analysis was very small compared to the number of human genes (190) identified with only one-species analysis (human data). The genes may be clinically relevant/important, as this small set achieved low misclassification rates of DLBCL subtypes. Additionally, the two subgroups defined by this cluster of human genes had significantly different survival functions, indicating that the stratification based on gene-expression profiling using the proposed mixture model provided improved insight into the clinical differences between the two cancer subtypes.

  5. Regional Analysis of Precipitation by Means of Bivariate Distribution Adjusted by Maximum Entropy; Analisis regional de precipitacion con base en una distribucion bivariada ajustada por maxima entropia

    Energy Technology Data Exchange (ETDEWEB)

    Escalante Sandoval, Carlos A.; Dominguez Esquivel, Jose Y. [Universidad Nacional Autonoma de Mexico (Mexico)

    2001-09-01

    The principle of maximum entropy (POME) is used to derive an alternative method of parameter estimation for the bivariate Gumbel distribution. A simple algorithm for this parameter estimation technique is presented. This method is applied to analyze the precipitation in a region of Mexico. Design events are compered with those obtained by the maximum likelihood procedure. According to the results, the proposed technique is a suitable option to be considered when performing frequency analysis of precipitation with small samples. [Spanish] El principio de maxima entropia, conocido como POME, es utilizado para derivar un procedimiento alternativo de estimacion de parametros de la distribucion bivariada de valores extremos con marginales Gumbel. El modelo se aplica al analisis de la precipitacion maxima en 24 horas en una region de Mexico y los eventos de diseno obtenidos son comparados con los proporcionados por la tecnica de maxima verosimilitud. De acuerdo con los resultados obtenidos, se concluye que la tecnica propuesta representa una buena opcion, sobre todo para el caso de muestras pequenas.

  6. Association between Stress Response Genes and Features of Diurnal Cortisol Curves in the Multi-Ethnic Study of Atherosclerosis: A New Multi-Phenotype Approach for Gene-Based Association Tests.

    Science.gov (United States)

    He, Zihuai; Payne, Erin K; Mukherjee, Bhramar; Lee, Seunggeun; Smith, Jennifer A; Ware, Erin B; Sánchez, Brisa N; Seeman, Teresa E; Kardia, Sharon L R; Diez Roux, Ana V

    2015-01-01

    The hormone cortisol is likely to be a key mediator of the stress response that influences multiple physiologic systems that are involved in common chronic disease, including the cardiovascular system, the immune system, and metabolism. In this paper, a candidate gene approach was used to investigate genetic contributions to variability in multiple correlated features of the daily cortisol profile in a sample of European Americans, African Americans, and Hispanic Americans from the Multi-Ethnic Study of Atherosclerosis (MESA). We proposed and applied a new gene-level multiple-phenotype analysis and carried out a meta-analysis to combine the ethnicity specific results. This new analysis, instead of a more routine single marker-single phenotype approach identified a significant association between one gene (ADRB2) and cortisol features (meta-analysis p-value=0.0025), which was not identified by three other commonly used existing analytic strategies: 1. Single marker association tests involving each single cortisol feature separately; 2. Single marker association tests jointly testing for multiple cortisol features; 3. Gene-level association tests separately carried out for each single cortisol feature. The analytic strategies presented consider different hypotheses regarding genotype-phenotype association and imply different costs of multiple testing. The proposed gene-level analysis integrating multiple cortisol features across multiple ethnic groups provides new insights into the gene-cortisol association.

  7. Testing gene-environment interaction in large-scale case-control association studies: possible choices and comparisons.

    Science.gov (United States)

    Mukherjee, Bhramar; Ahn, Jaeil; Gruber, Stephen B; Chatterjee, Nilanjan

    2012-02-01

    Several methods for screening gene-environment interaction have recently been proposed that address the issue of using gene-environment independence in a data-adaptive way. In this report, the authors present a comparative simulation study of power and type I error properties of 3 classes of procedures: 1) the standard 1-step case-control method; 2) the case-only method that requires an assumption of gene-environment independence for the underlying population; and 3) a variety of hybrid methods, including empirical-Bayes, 2-step, and model averaging, that aim at gaining power by exploiting the assumption of gene-environment independence and yet can protect against false positives when the independence assumption is violated. These studies suggest that, although the case-only method generally has maximum power, it has the potential to create substantial false positives in large-scale studies even when a small fraction of markers are associated with the exposure under study in the underlying population. All the hybrid methods perform well in protecting against such false positives and yet can retain substantial power advantages over standard case-control tests. The authors conclude that, for future genome-wide scans for gene-environment interactions, major power gain is possible by using alternatives to standard case-control analysis. Whether a case-only type scan or one of the hybrid methods should be used depends on the strength and direction of gene-environment interaction and association, the level of tolerance for false positives, and the nature of replication strategies.

  8. Replacement of Hydrochlorofluorocarbon (HCFC) -225 Solvent for Cleaning and Verification Sampling of NASA Propulsion Oxygen Systems Hardware, Ground Support Equipment, and Associated Test Systems

    Science.gov (United States)

    Burns, H. D.; Mitchell, M. A.; McMillian, J. H.; Farner, B. R.; Harper, S. A.; Peralta, S. F.; Lowrey, N. M.; Ross, H. R.; Juarez, A.

    2015-01-01

    Since the 1990's, NASA's rocket propulsion test facilities at Marshall Space Flight Center (MSFC) and Stennis Space Center (SSC) have used hydrochlorofluorocarbon-225 (HCFC-225), a Class II ozone-depleting substance, to safety clean and verify the cleanliness of large scale propulsion oxygen systems and associated test facilities. In 2012 through 2014, test laboratories at MSFC, SSC, and Johnson Space Center-White Sands Test Facility collaborated to seek out, test, and qualify an environmentally preferred replacement for HCFC-225. Candidate solvents were selected, a test plan was developed, and the products were tested for materials compatibility, oxygen compatibility, cleaning effectiveness, and suitability for use in cleanliness verification and field cleaning operations. Honewell Soltice (TradeMark) Performance Fluid (trans-1-chloro-3,3, 3-trifluoropropene) was selected to replace HCFC-225 at NASA's MSFC and SSC rocket propulsion test facilities.

  9. Associative vocabulary learning: development and testing of two paradigms for the (re- acquisition of action- and object-related words.

    Directory of Open Access Journals (Sweden)

    Nils Freundlieb

    Full Text Available Despite a growing number of studies, the neurophysiology of adult vocabulary acquisition is still poorly understood. One reason is that paradigms that can easily be combined with neuroscientfic methods are rare. Here, we tested the efficiency of two paradigms for vocabulary (re- acquisition, and compared the learning of novel words for actions and objects. Cortical networks involved in adult native-language word processing are widespread, with differences postulated between words for objects and actions. Words and what they stand for are supposed to be grounded in perceptual and sensorimotor brain circuits depending on their meaning. If there are specific brain representations for different word categories, we hypothesized behavioural differences in the learning of action-related and object-related words. Paradigm A, with the learning of novel words for body-related actions spread out over a number of days, revealed fast learning of these new action words, and stable retention up to 4 weeks after training. The single-session Paradigm B employed objects and actions. Performance during acquisition did not differ between action-related and object-related words (time*word category: p = 0.01, but the translation rate was clearly better for object-related (79% than for action-related words (53%, p = 0.002. Both paradigms yielded robust associative learning of novel action-related words, as previously demonstrated for object-related words. Translation success differed for action- and object-related words, which may indicate different neural mechanisms. The paradigms tested here are well suited to investigate such differences with neuroscientific means. Given the stable retention and minimal requirements for conscious effort, these learning paradigms are promising for vocabulary re-learning in brain-lesioned people. In combination with neuroimaging, neuro-stimulation or pharmacological intervention, they may well advance the understanding of

  10. Associative vocabulary learning: development and testing of two paradigms for the (re-) acquisition of action- and object-related words.

    Science.gov (United States)

    Freundlieb, Nils; Ridder, Volker; Dobel, Christian; Enriquez-Geppert, Stefanie; Baumgaertner, Annette; Zwitserlood, Pienie; Gerloff, Christian; Hummel, Friedhelm C; Liuzzi, Gianpiero

    2012-01-01

    Despite a growing number of studies, the neurophysiology of adult vocabulary acquisition is still poorly understood. One reason is that paradigms that can easily be combined with neuroscientfic methods are rare. Here, we tested the efficiency of two paradigms for vocabulary (re-) acquisition, and compared the learning of novel words for actions and objects. Cortical networks involved in adult native-language word processing are widespread, with differences postulated between words for objects and actions. Words and what they stand for are supposed to be grounded in perceptual and sensorimotor brain circuits depending on their meaning. If there are specific brain representations for different word categories, we hypothesized behavioural differences in the learning of action-related and object-related words. Paradigm A, with the learning of novel words for body-related actions spread out over a number of days, revealed fast learning of these new action words, and stable retention up to 4 weeks after training. The single-session Paradigm B employed objects and actions. Performance during acquisition did not differ between action-related and object-related words (time*word category: p = 0.01), but the translation rate was clearly better for object-related (79%) than for action-related words (53%, p = 0.002). Both paradigms yielded robust associative learning of novel action-related words, as previously demonstrated for object-related words. Translation success differed for action- and object-related words, which may indicate different neural mechanisms. The paradigms tested here are well suited to investigate such differences with neuroscientific means. Given the stable retention and minimal requirements for conscious effort, these learning paradigms are promising for vocabulary re-learning in brain-lesioned people. In combination with neuroimaging, neuro-stimulation or pharmacological intervention, they may well advance the understanding of language learning

  11. A Mixed Model Approach to Meta-Analysis of Diagnostic Studies with Binary Test Outcome

    Science.gov (United States)

    Doebler, Philipp; Holling, Heinz; Bohning, Dankmar

    2012-01-01

    We propose 2 related models for the meta-analysis of diagnostic tests. Both models are based on the bivariate normal distribution for transformed sensitivities and false-positive rates. Instead of using the logit as a transformation for these proportions, we employ the "t"[subscript alpha] family of transformations that contains the log, logit,…

  12. A Comparison of Two Tests for the Significance of a Mean Vector.

    Science.gov (United States)

    1978-01-01

    package” based upon the technique of Marsaglia [6] for generating standard normal deviates. A random observation from the bivariate normal population...Marcel Dekker, Inc. (6] Lehmann , E. L. (1959) . Testing Statistical Hypotheses, New York : John Wiley & Sons, Inc. (7] Marsaglia , G. ( 1961

  13. Association between sexual role and HIV status among Peruvian men who have sex with men seeking an HIV test: a cross-sectional analysis.

    Science.gov (United States)

    McLean, Sarah A; Galea, Jerome T; Prudden, Holly J; Calvo, Gino; Sánchez, Hugo; Brown, Brandon

    2016-08-01

    In Latin America, sexual role, sexual identity and sexual practices are intricately related; the roles activo, pasivo and moderno often encompass sexual identity and sexual practices. We aimed to understand the association between sexual role and HIV status in Peruvian men who have sex with men. HIV-testing services at Epicentro Salud, a Peruvian gay men's health centre, were paired with clinic data on demographics and sexual behaviour. Bidirectional stepwise logistic regression was conducted to determine associations between sexual role and HIV status. Of 366 clients who underwent HIV testing, 86 (23.5%) tested positive. There was a strong association between sexual role ('activo' or typically insertive, 'pasivo' or typically receptive, 'moderno' or typically versatile) and a positive HIV test (p = 0.002). Compared to clients with an activo role, those who reported a pasivo (OR = 6.14) and moderno (OR = 6.26) role were more likely to test positive for HIV. Sexual role was associated with sexual identity (gay, straight and bisexual) and gender of partners in the past six months. Self-reported pasivo and moderno sexual roles were strongly associated with a positive HIV test result. Further research should examine differences in sexual practices between sexual role groups.

  14. A PLSPM-based test statistic for detecting gene-gene co-association in genome-wide association study with case-control design.

    Science.gov (United States)

    Zhang, Xiaoshuai; Yang, Xiaowei; Yuan, Zhongshang; Liu, Yanxun; Li, Fangyu; Peng, Bin; Zhu, Dianwen; Zhao, Jinghua; Xue, Fuzhong

    2013-01-01

    For genome-wide association data analysis, two genes in any pathway, two SNPs in the two linked gene regions respectively or in the two linked exons respectively within one gene are often correlated with each other. We therefore proposed the concept of gene-gene co-association, which refers to the effects not only due to the traditional interaction under nearly independent condition but the correlation between two genes. Furthermore, we constructed a novel statistic for detecting gene-gene co-association based on Partial Least Squares Path Modeling (PLSPM). Through simulation, the relationship between traditional interaction and co-association was highlighted under three different types of co-association. Both simulation and real data analysis demonstrated that the proposed PLSPM-based statistic has better performance than single SNP-based logistic model, PCA-based logistic model, and other gene-based methods.

  15. Assessing the Factors Associated with Sexual Harassment among Young Female Migrant Workers in Nepal

    Science.gov (United States)

    Puri, Mahesh; Cleland, John

    2007-01-01

    This article explores the extent of, and factors associated with, sexual harassment of young female migrant workers in the carpet and garment factories in Kathmandu Valley. Information is drawn from a survey of 550 female workers aged 14 to 19 and 12 in-depth case histories. Bivariate and multivariate techniques were applied to identify the…

  16. A word association response approach toward lexical relationships within the mental lexicon of second language learners: pedagogic ideas from testing McCarthy's theories on Japanese students.

    Science.gov (United States)

    Murphy, Robert S; Post, Michael D

    2009-06-01

    Through use of word association as detailed in McCarthy (1990) this paper will explore pedagogic implications derived from the following three points in relation to the lexical development of Japanese learners of English: 1) the ability of word association tests to examine the mental links between words in learners' developing mental lexicon, 2) the importance of phonological similarities for lower level students and 3) the correlation between the results from a word association test with the characteristic types of word association patterns discussed in McCarthy (1990). It will be argued that while lexical development within the mental lexicon is difficult to delineate due to overlap of organizational categories, the patterns of syntactic, semantic and conceptual relations between learned words is apparent within the retrieval process for word association and that additionally, context may play a vital role in how words are construed along the links within the mental lexicon. Pedagogic ideas and future research ideas are detailed.

  17. Analysis of factors associated with excess weight in school children

    Science.gov (United States)

    Pinto, Renata Paulino; Nunes, Altacílio Aparecido; de Mello, Luane Marques

    2016-01-01

    Abstract Objective: To determine the prevalence of overweight and obesity in schoolchildren aged 10 to 16 years and its association with dietary and behavioral factors. Methods: Cross-sectional study that evaluated 505 adolescents using a structured questionnaire and anthropometric data. The data was analyzed through the T Test for independent samples and Mann-Whitney Test to compare means and medians, respectively, and Chi2 Test for proportions. Prevalence ratio (RP) and the 95% confidence interval was used to estimate the degree of association between variables. The logistic regression was employed to adjust the estimates to confounding factors. The significance level of 5% was considered for all analysis. Results: Excess weight was observed in 30.9% of the schoolchildren: 18.2% of overweight and 12.7% of obesity. There was no association between weight alterations and dietary/behavioral habits in the bivariate and multivariate analyses. However, associations were observed in relation to gender. Daily consumption of sweets [PR=0.75 (0.64-0.88)] and soft drinks [PR=0.82 (0.70-0.97)] was less frequent among boys; having lunch daily was slightly more often reported by boys [OR=1.11 (1.02-1.22)]. Physical activity practice of (≥3 times/week) was more often mentioned by boys and the association measures disclosed two-fold more physical activity in this group [PR=2.04 (1.56-2.67)] when compared to girls. Approximately 30% of boys and 40% of girls stated they did not perform activities requiring energy expenditure during free periods, with boys being 32% less idle than girls [PR=0.68 (0.60-0.76)]. Conclusions: A high prevalence of both overweight and obesity was observed, as well as unhealthy habits in the study population, regardless of the presence of weight alterations. Health promotion strategies in schools should be encouraged, in order to promote healthy habits and behaviors among all students. PMID:27321919

  18. Associação glicemia de jejum e fatores de risco como teste para rastreamento do diabete gestacional Fasting glycemia associated with risk factors as a screening test for gestational diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Wilson Ayach

    2005-09-01

    Full Text Available OBJETIVOS: comparar dois testes de rastreamento do diabete gestacional. MÉTODOS: estudo prospectivo no qual foram avaliadas 356 gestantes, sem diagnóstico prévio do diabete melito, submetidas, de modo independente, a dois testes de rastreamento: associação glicemia de jejum e fator de risco (GJ+FR e teste oral simplificado de tolerância à glicose (TTG50g. A comparação entre os métodos foi realizada pelos índices de sensibilidade (S, especificidade (E e valores preditivos positivo (VPP e negativo (VPN, resultados falsos, positivos (FP e negativos (FN e pela diferença dos resultados observados e esperados, avaliada pelo teste do Qui-quadrado (pOBJECTIVES: compare two gestational diabetes tests. METHODS: a prospective study in which 356 pregnant women, with no previous diabetes mellitus diagnoses independently submitted to two tests; fasting glycemia and risk factor association (FG+RF and the simplified oral test for glucose tolerance (TTG50g. Methods of comparison were performed by sensitivity (S and (ES specificity indexes, positive predictive values (PPV and negative predictive values (NPV, false results, false positive (FP and false negative (FN and by the difference of the results determined and expected, evaluated through the Chi-Square Test (p<0.05. RESULTS: FG+RF association determined diagnostic confirmation in a larger number of patients (187; 52.5% than TTG50g (49; 13.8%. This difference was significant (p<0.05. The FG+RF association indicated a sensitivity of 83.7% and negative predictive value (NPV of 95.3% as compared to TTG50g. CONCLUSIONS: the high sensitivity rates and NPV from the association of FG+RF as compared to TTG50g and its simplicity, practicality, low cost and easy replication are positive qualities for gestational diabetes testing indication.

  19. Further Tests of Changes in Fish Escape Behavior Resulting from Sublethal Stresses Associated with Hydroelectric Turbine Passage

    Energy Technology Data Exchange (ETDEWEB)

    Ryon, M.G.

    2004-10-20

    and another 70 under control conditions (either transferred from the holding tank or injected into the Alden loop downstream of turbine). The resulting image files were analyzed for a variety of behavioral measures including: presence of a startle response, time to first reaction, duration of reaction, time to formation of the maximum C-shape, time to completion of the C-shape, completeness of the C-shape, direction of turn, and degree of turn. The data were evaluated for statistical significance and patterns of response were identified. The most immediate measure of potential changes in fish behavior was whether test and control fish exhibited a startle response. Unlike earlier studies, there was no significant difference among the treatment group and the controls for startle response. The majority of rainbow trout in all groups responded to the startle stimulus. There were however, significant differences in some of the particular aspects of the subsequent escape behavior. The time to first reaction, the duration of the reaction, and the times associated with maximum C-shape formation were all significantly different between the tank controls and the two groups of fish injected into the Alden turbine loop. There were no significant differences in behavioral responses between the trout passed through the turbine runner and those injected downstream of the runner. Other behavioral parameters, such as C-shape completeness ratio, were not significantly affected. The effect of the Alden turbine loop on some aspects of the escape behavior suggest that the process of movement through the system is important, but that the role of the added stress, if any, of passage through the turbine runner is minimal. It may be important that statistically significant differences in timing of phases of the startle response were detected, even though the majority of stressed fish still exhibited the startle response. This is in contrast to earlier studies, where timing of phases of the

  20. The SDF-1 rs1801157 Polymorphism is Associated with Cancer Risk: An Update Pooled Analysis and FPRP Test of 17,876 Participants.

    Science.gov (United States)

    Tong, Xiang; Ma, Yao; Deng, Huajiang; Wang, Xixi; Liu, Sitong; Yan, Zhipeng; Peng, Shifeng; Fan, Hong

    2016-06-06

    The stromal cell derived factor-1 (SDF-1) rs1801157 gene polymorphism has been implicated in susceptibility to cancer, but the results were inconclusive. The current study was to precisely investigate the association between SDF-1 rs1801157 polymorphism and cancer risk using meta-analysis and the false positive report probability (FPRP) test. All 17,876 participants were included in the study. The meta-analysis results indicated a significant association between the SDF-1 rs1801157 polymorphism and cancer risk. By subgroup analyses, the results detected that the SDF-1 rs1801157 polymorphism was associated with cancer susceptibility among Asians and Caucasians. Additionally, we also found significant associations between the SDF-1 rs1801157 polymorphism and susceptibility to different types of cancer. However, to avoid a "false positive report", we further investigated the significant associations observed in the present meta-analysis using the FPRP test. Interestingly, the results of the FPRP test indicated that only 4 gene models were truly associated with cancer risk, especially in Asians. Moreover, we confirmed that the SDF-1 rs1801157 gene polymorphism was only associated with lung and urologic cancer risk. In summary, this study suggested that the SDF-1 rs1801157 polymorphism may serve as a risk factor for cancer development among Asians, especially an increased risk of urologic and lung cancers.

  1. 运动性心理疲劳的 IAT测量%An Implicit Association Test for Assessing Athlete Burnout

    Institute of Scientific and Technical Information of China (English)

    葛杨; 张力为

    2014-01-01

    编制了以训练和生活情境为目标刺激,运动性心理疲劳积极/消极词为属性刺激的内隐联想测验(IAT ),并通过4个研究探索其测量运动性心理疲劳的可行性。招募35名大学生运动员完成研究一“IAT 重测信度检验”和研究二“假装情境对内隐测验的影响”,结果表明,所编制的IAT 测验具有较好的跨时间、跨情境的稳定性。研究3对67名大学生运动员施测内隐外显心理疲劳问卷,考察 IAT 与外显运动性心理疲劳相关变量的关系,发现图片和文字版本 IAT 相关显著,IAT 得分与外显心理疲劳相关较弱,与运动动机相关显著,并对外显心理疲劳测验预测运动动机和训练比赛满意感有增值贡献。4对21名国家队运动员比赛前后的追踪研究发现,赛前 IAT 得分能够预测赛后1名教练员对运动员比赛表现的评价。总之,所编制的运动性心理疲劳IAT 具有较好的信度,并能够预测部分校标,一定程度上反映了运动员的消极心理状态,但不能替代现有的外显测验。%The Implicit Association Test (IAT ) was adapted to measure athlete burnout by as-sessing associations of training words/pictures (vs .daily-life words/pictures ) with negative (vs .positive) athlete burnout words .Study 1 showed that the IAT-Burnout exhibited good re-test consistency .Study 2 revealed that the IAT-Burnout was unaffected by a faking instruc-tion .Study 3 examined the validities of implicit and explicit measures and showed that the IAT-Burnout has a weak correlation with explicit burnout measures ,but was related to the sport motivation and competition satisfaction .Study 4 found that coach-rated indicators of com-petition performance were predicted by the IAT .Taken together ,these studies show that the IAT-Burnout is a reliable measure that is able to predict some of the criterion variables . Though it cannot replace existing explicit measurements ,it

  2. The Application of Bivariate Threshold Excess Model in the Atmospheric Environment%二元超阈值模型在环境中的应用

    Institute of Scientific and Technical Information of China (English)

    任国荣

    2012-01-01

    In recent years, more and more air pollutants have been discharged into the atmosphere. When pollutants in the atmosphere reach a certain amount, some kinds of air pollution events would happen. The bivariate threshold excess model and its application in atmospheric environment are mainly studied. When studying the extremes values of two variables, each variable can be modeled using univariate techniques, however, the extreme value inter-relationships would also be needed to study. A measure to study tail correlation between two variables is given. Then it was applied to the indicators of atmospheric environment in Shanghai. The result is that APIs for re-spirable particulate matter and for sulfur dioxide have a stronger tail dependence. In order to get a better understanding of two indicators, a bivariate threshold excess model is need to build. Firstly, distribution function for every index is established. Secondly, asymmetric Logistic model is selected as the structure functions for APIs of re-spirable particulate matter and sulfur dioxide. Then with this functions distribution of two indexes in case of exceeding the threshold is established, which can be used to analysis and forecast how the two indexes change in future.%近年来,随着现代工业和交通运输业的飞速发展,大气中排放物的数量越来越多,种类也越来越复杂,产生了越来越严重的大气环境污染.本文主要研究二元超阈值方法及其在大气环境中的应用.研究二元极值分布,除了要知道各个变量的边缘分布,还需要知道两个变量之间的尾部相关性.给出了两种度量随机变量尾部相关性的方法,并将其应用于上海市大气环境指标中,发现可吸入颗粒物API与二氧化硫API具有较强的尾部相关性.为了更深入地了解两个指标间的尾部相关性及其两个指标的走势,建立了二元超阈值模型.首先,根据阈值模型建立了每个指标的分布

  3. Inference for the Bivariate and Multivariate Hidden Truncated Pareto(type II) and Pareto(type IV) Distribution and Some Measures of Divergence Related to Incompatibility of Probability Distribution

    Science.gov (United States)

    Ghosh, Indranil

    2011-01-01

    Consider a discrete bivariate random variable (X, Y) with possible values x[subscript 1], x[subscript 2],..., x[subscript I] for X and y[subscript 1], y[subscript 2],..., y[subscript J] for Y. Further suppose that the corresponding families of conditional distributions, for X given values of Y and of Y for given values of X are available. We…

  4. BIVARIATE POLYNOMIAL BASED SECRET SHARING TECHNOLOGY STUDY%基于二元多项式的秘密分享技术研究

    Institute of Scientific and Technical Information of China (English)

    唐聃; 舒红平

    2012-01-01

    At present most secret sharing schemes follow the realization idea of classic Shamir scheme, namely the unary polynomial based (k, n) threshold scheme. Such schemes inherit many advantages of Shamir scheme, such as simple thought, easy implementation, harmony of perfection and idealness and so on. However, still there is a defect in these schemes that their access structure is not rich enough, so that the popularization of secret sharing technology in practical applications is seriously limited. In view of this situation, the paper proposes a bivariate polynomial based secret sharing scheme. Besides possessing the various advantages of Shamir scheme, the access structure of the new scheme is greatly enriched. In addition, the new scheme can easily be introduced to image secret sharing, audio secret sharing as well as other fields.%当前大多数秘密分享方案的设计沿用了经典Shamir方案的实现思路,即基于一元多项式的(k,n)门限方案.此类方案继承了Shamir方案的诸多优点,如思路简洁便于实现、兼有完备性(Perfect)和理想性(Ideal)等.然而,这一类方案也有着准入结构不够丰富的缺陷,极大地限制了秘密分享技术在实际应用中的推广.针对这一情况,提出一种基于二元多项式的秘密分享方案,该方案兼有Shamir方案的诸多优点,而准入结构又得到了极大的丰富.此外,新方案很容易推广到图像秘密分享、音频秘密分享等领域.

  5. Landslide susceptibility assessment in Lianhua County (China): A comparison between a random forest data mining technique and bivariate and multivariate statistical models

    Science.gov (United States)

    Hong, Haoyuan; Pourghasemi, Hamid Reza; Pourtaghi, Zohre Sadat

    2016-04-01

    Landslides are an important natural hazard that causes a great amount of damage around the world every year, especially during the rainy season. The Lianhua area is located in the middle of China's southern mountainous area, west of Jiangxi Province, and is known to be an area prone to landslides. The aim of this study was to evaluate and compare landslide susceptibility maps produced using the random forest (RF) data mining technique with those produced by bivariate (evidential belief function and frequency ratio) and multivariate (logistic regression) statistical models for Lianhua County, China. First, a landslide inventory map was prepared using aerial photograph interpretation, satellite images, and extensive field surveys. In total, 163 landslide events were recognized in the study area, with 114 landslides (70%) used for training and 49 landslides (30%) used for validation. Next, the landslide conditioning factors-including the slope angle, altitude, slope aspect, topographic wetness index (TWI), slope-length (LS), plan curvature, profile curvature, distance to rivers, distance to faults, distance to roads, annual precipitation, land use, normalized difference vegetation index (NDVI), and lithology-were derived from the spatial database. Finally, the landslide susceptibility maps of Lianhua County were generated in ArcGIS 10.1 based on the random forest (RF), evidential belief function (EBF), frequency ratio (FR), and logistic regression (LR) approaches and were validated using a receiver operating characteristic (ROC) curve. The ROC plot assessment results showed that for landslide susceptibility maps produced using the EBF, FR, LR, and RF models, the area under the curve (AUC) values were 0.8122, 0.8134, 0.7751, and 0.7172, respectively. Therefore, we can conclude that all four models have an AUC of more than 0.70 and can be used in landslide susceptibility mapping in the study area; meanwhile, the EBF and FR models had the best performance for Lianhua

  6. Further Tests of Changes in Fish Escape Behavior Resulting from Sublethal Stresses Associated with Hydroelectric Turbine Passage

    Energy Technology Data Exchange (ETDEWEB)

    Ryon, M.G.

    2004-10-20

    and another 70 under control conditions (either transferred from the holding tank or injected into the Alden loop downstream of turbine). The resulting image files were analyzed for a variety of behavioral measures including: presence of a startle response, time to first reaction, duration of reaction, time to formation of the maximum C-shape, time to completion of the C-shape, completeness of the C-shape, direction of turn, and degree of turn. The data were evaluated for statistical significance and patterns of response were identified. The most immediate measure of potential changes in fish behavior was whether test and control fish exhibited a startle response. Unlike earlier studies, there was no significant difference among the treatment group and the controls for startle response. The majority of rainbow trout in all groups responded to the startle stimulus. There were however, significant differences in some of the particular aspects of the subsequent escape behavior. The time to first reaction, the duration of the reaction, and the times associated with maximum C-shape formation were all significantly different between the tank controls and the two groups of fish injected into the Alden turbine loop. There were no significant differences in behavioral responses between the trout passed through the turbine runner and those injected downstream of the runner. Other behavioral parameters, such as C-shape completeness ratio, were not significantly affected. The effect of the Alden turbine loop on some aspects of the escape behavior suggest that the process of movement through the system is important, but that the role of the added stress, if any, of passage through the turbine runner is minimal. It may be important that statistically significant differences in timing of phases of the startle response were detected, even though the majority of stressed fish still exhibited the startle response. This is in contrast to earlier studies, where timing of phases of the

  7. Psychological Factors Associated with Genetic Test Decision-Making among Parents of Children with Autism Spectrum Disorders in Taiwan

    Science.gov (United States)

    Xu, Lei; Richman, Alice R.

    2015-01-01

    Making decisions to undergo Autism Spectrum Disorders (ASD) genetic testing can be challenging. It is important to understand how the perceptions of affected individuals might influence testing decision-making. Although evidence has shown that psychological factors are important in predicting testing decisions, affect-type variables have been…

  8. Drug Testing in Schools: Policies, Practices, and Association with Student Drug Use. YES Occasional Papers. Paper 2

    Science.gov (United States)

    Yamaguchi, Ryoko; Johnston, Lloyd D.; O'Malley, Patrick M.

    2003-01-01

    Despite considerable recent public and judicial attention to the issue of drug testing, little empirical research has focused on the relationship between drug testing in schools and the actual use of illicit drugs by students. To explore this issue, we use school-level survey data about drug testing from the Youth, Education, and Society study and…

  9. Factors associated with serological cure and the serofast state of HIV-negative patients with primary, secondary, latent, and tertiary syphilis.

    Directory of Open Access Journals (Sweden)

    Man-Li Tong

    Full Text Available BACKGROUND: Some syphilis patients remain in a serologically active state after the recommended therapy. We currently know too little about the characteristics of this serological response. METHODS: We conducted a cohort study using the clinical database from Zhongshan Hospital, Medical College of Xiamen. In total, 1,327 HIV-negative patients with primary, secondary, latent, and tertiary syphilis were enrolled. Bivariate and multivariate analyses were utilised to identify factors associated with a serological cure and serofast state in syphilis patients one year after therapy. Chi-square tests were used to determine the differences in the serological cure rate across different therapy time points. RESULTS: One year after the recommended therapy, 870 patients achieved a serological cure, and 457 patients (34.4% remained in the serofast state. The serological cure rate increased only within the first 6 months. The bivariate analysis indicated that male or younger patients had a higher likelihood of a serological cure than female or older patients. Having a baseline titre ≤ 1∶2 or ≥ 1∶64 was associated with an increased likelihood of a serological cure. The serological cure rate decreased for the different disease stages in the order of primary, secondary, latent, and tertiary syphilis. A distinction should be drawn between early and late syphilis. The multivariate analysis indicated that a serological cure was significantly associated with the disease phase, gender, age, and baseline rapid plasma reagin (RPR titre. CONCLUSIONS: The serofast state is common in clinical work. After one year of the recommended therapy, quite a few syphilis patients remained RPR positive. The primary endpoint of the study indicated that disease phase, gender, age and baseline RPR titre were crucial factors associated with a serological cure.

  10. Laboratory costing system based on number and type of test: its association with the Welcan workload measurement system.

    Science.gov (United States)

    Tarbit, I F

    1990-02-01

    A laboratory costing system which recovers all costs against tests, rather than using both test and request charges, was developed. Methods of recovering costs of routine and emergency services, of capital investment in equipment, of instrument maintenance costs and of general hospital overheads were considered. The Welcan unit system of workload measurement was applied to a range of test procedures. Both the Welcan unit value and unit value adjusted fro calibration and quality control (Welcan based weighting) correlated only moderately with locally derived analytical time per test and correlated poorly with direct analytical cost per test. The correlation of direct analytical cost per test with total cost per test was much stronger than that of analytical time per test with direct analytical cost per test. The data suggest that neither Welcan unit values, Welcan based weightings, nor locally derived analytical time per test can truly reflect total resource consumption for the provision of a range of test procedures. This factor should be borne in mind when applying operational or performance indicators based on Welcan units.

  11. Follow-Up Study of Tuberculosis-Exposed Supermarket Customers with Negative Tuberculin Skin Test Results in Association with Positive Gamma Interferon Release Assay Results▿

    Science.gov (United States)

    Franken, Willeke P. J.; Koster, Ben F. P. J.; Bossink, Ailko W. J.; Thijsen, Steven F. T.; Bouwman, John J. M.; van Dissel, Jaap T.; Arend, Sandra M.

    2007-01-01

    We report a follow-up study of 29 subjects with negative tuberculin skin test (TST) results in association with positive gamma interferon release assay (IGRA) results, mainly due to responses to CFP-10 in the T-SPOT.TB assay, during a contact investigation. One year later, 12/29 subjects (41%) had converted to positive TST results in association with negative IGRA results. PMID:17626157

  12. Flavor-postingestive consequence associations incorporate the behaviorally opposing effects of positive reinforcement and anticipated satiety: implications for interpreting two-bottle tests.

    Science.gov (United States)

    Warwick, Z S; Weingarten, H P

    1996-09-01

    Rats consuming distinctively flavored solutions containing different numbers of calories learn to associate each flavor with the ensuing postingestive effects ("flavor-postingestive consequence learning"). The hallmark of such learning is preferential consumption of one of the flavors in two-bottle tests (both flavors presented in nutrient-identical solutions). Two experiments were conducted to characterize the relationship between the number of calories associated with flavors and subsequent preferences in two-bottle tests. In Experiment 1, three groups of rats each associated distinctive flavors with real-fed sugar and with sham-fed sugar. The groups differed in the concentration of sucrose (8%, 14%, 24%) with which they were trained. In two-bottle tests rats trained with 8% sucrose preferred the real-fed flavor, whereas rats trained with 24% sucrose preferred the sham-fed flavor. Rats trained with 14% sucrose were intermediate to the other groups. In Experiment 2, two groups of rats associated distinctive flavors with two concentrations of real-fed sucrose. In two-bottle tests, the group trained with 1% and 5% sucrose preferred the flavor paired with the higher concentration, whereas the group trained with 5% and 30% sucrose preferred the flavor paired with the lower concentration. These findings suggest that flavor-postingestive consequence learning incorporates both positive reinforcement, which has the behavioral effect of increasing intake of the associated flavor, and anticipated satiety, which has the behavioral effect of suppressing intake of the associated flavor. When a flavor is associated with relatively few calories, the positive reinforcing effect predominates over anticipated satiety. However, when a flavor is associated with a greater number of calories, anticipated satiety predominates over the positive reinforcing effect.

  13. Genetic correlates of brain aging on MRI and cognitive test measures: a genome-wide association and linkage analysis in the Framingham study

    OpenAIRE

    2007-01-01

    Abstract Background Brain magnetic resonance imaging (MRI) and cognitive tests can identify heritable endophenotypes associated with an increased risk of developing stroke, dementia and Alzheimer's disease (AD). We conducted a genome-wide association (GWA) and linkage analysis exploring the genetic basis of these endophenotypes in a community-based sample. Methods A total of 705 stroke- and dementia-free Framingham participants (age 62 +9 yrs, 50% male) who underwent volumetric brain MRI and ...

  14. Impaired or Not Impaired, That Is the Question: Navigating the Challenges Associated with Using Canadian Normative Data in a Comprehensive Test Battery That Contains American Tests.

    Science.gov (United States)

    Chevalier, Thérèse M; Stewart, Garth; Nelson, Monty; McInerney, Robert J; Brodie, Norman

    2016-08-01

    It has been well documented that IQ scores calculated using Canadian norms are generally 2-5 points lower than those calculated using American norms on the Wechsler IQ scales. However, recent findings have demonstrated that the difference may be significantly larger for individuals with certain demographic characteristics, and this has prompted discussion about the appropriateness of using the Canadian normative system with a clinical population in Canada. This study compared the interpretive effects of applying the American and Canadian normative systems in a clinical sample. We used a multivariate analysis of variance (ANOVA) to calculate differences between IQ and Index scores in a clinical sample, and mixed model ANOVAs to assess the pattern of differences across age and ability level. As expected, Full Scale IQ scores calculated using Canadian norms were systematically lower than those calculated using American norms, but differences were significantly larger for individuals classified as having extremely low or borderline intellectual functioning when compared with those who scored in the average range. Implications of clinically different conclusions for up to 52.8% of patients based on these discrepancies highlight a unique dilemma facing Canadian clinicians, and underscore the need for caution when choosing a normative system with which to interpret WAIS-IV results in the context of a neuropsychological test battery in Canada. Based on these findings, we offer guidelines for best practice for Canadian clinicians when interpreting data from neuropsychological test batteries that include different normative systems, and suggestions to assist with future test development.

  15. "We as Black Men Have to Encourage Each other:" Facilitators and Barriers Associated with HIV Testing among Black/African American Men in Rural Florida.

    Science.gov (United States)

    Murray, Ashley; Toledo, Lauren; Brown, Emma Ej; Sutton, Madeline Y

    2017-01-01

    HIV testing for some African American men remains a challenge, and effective interventions are lacking. We explored facilitators and barriers associated with HIV testing among heterosexual African American men in rural Florida. We conducted focus group interviews with 67 African American men who were low-income, and HIV-uninfected based on prior testing or had unknown HIV status. Using computer-assisted thematic analyses, we examined transcribed focus group responses for main themes. Thematic analyses revealed three main themes regarding facilitators of HIV testing: 1) using preferred HIV testing community locations (park, library, gym); 2) receiving incentives (food or money); and 3) the importance of peer-led messaging for free, rapid HIV testing. Barriers included HIV testing at the local health department, and perceived social and emotional consequences to testing and the possibility of receiving a positive result. Effective HIV testing interventions for heterosexual African American men in rural Florida may need to incorporate suggested facilitators and reduce perceived barriers in order to improve HIV testing strategies.

  16. Stress, Social Support, and Depression: A Test of the Stress-Buffering Hypothesis in a Mexican Sample

    Science.gov (United States)

    Raffaelli, Marcela; Andrade, Flavia C. D.; Wiley, Angela R.; Sanchez-Armass, Omar; Edwards, Laura L.; Aradillas-Garcia, Celia

    2013-01-01

    This study examined social support as a potential moderator between stress and depressive symptoms among Mexican university applicants aged 16--21 years ("N" = 6,715; "M" age = 17.9 years; 55% female). In bivariate analyses, perceived stress was associated with higher levels of depressive symptoms, and social support with lower…

  17. Modified forelimb grip strength test detects aging-associated physiological decline in skeletal muscle function in male mice

    Science.gov (United States)

    Takeshita, Hikari; Yamamoto, Koichi; Nozato, Satoko; Inagaki, Tadakatsu; Tsuchimochi, Hirotsugu; Shirai, Mikiyasu; Yamamoto, Ryohei; Imaizumi, Yuki; Hongyo, Kazuhiro; Yokoyama, Serina; Takeda, Masao; Oguro, Ryosuke; Takami, Yoichi; Itoh, Norihisa; Takeya, Yasushi; Sugimoto, Ken; Fukada, So-ichiro; Rakugi, Hiromi

    2017-01-01

    The conventional forelimb grip strength test is a widely used method to assess skeletal muscle function in rodents; in this study, we modified this method to improve its variability and consistency. The modified test had lower variability among trials and days than the conventional test in young C57BL6 mice, especially by improving the variabilities in male. The modified test was more sensitive than the conventional test to detect a difference in motor function between female and male mice, or between young and old male mice. When the modified test was performed on male mice during the aging process, reduction of grip strength manifested between 18 and 24 months of age at the group level and at the individual level. The modified test was similar to the conventional test in detecting skeletal muscle dysfunction in young male dystrophic mice. Thus, the modified forelimb grip strength test, with its improved validity and reliability may be an ideal substitute for the conventional method. PMID:28176863

  18. A Useful Approximate Formula for the Determination of the Regions of the Sequential Test for the Correlation Coefficient.

    Science.gov (United States)

    1979-02-15

    A simple approximate formula is shown to be remarkably accurate for the determination of the regions of the sequential test for the correlation ... coefficient , rho, when the variates follow a bivariate normal distribution. The approximate results are compared with the exact values and with an

  19. Factors Associated with Road Accidents among Brazilian Motorcycle Couriers

    OpenAIRE

    da Silva, Daniela Wosiack; Andrade, Selma Maffei de; Soares,Dorotéia Fátima Pelissari de Paula; Mathias,Thais Aidar de Freitas; Matsuo, Tiemi; de Souza, Regina Kazue Tanno

    2012-01-01

    The objective of the study was to identify factors associated with reports of road accidents, among motorcycle couriers in two medium-sized municipalities in southern Brazil. A self-administered questionnaire was answered by motorcycle couriers that had worked for at least 12 months in this profession. The outcomes analyzed were reports on accidents and serious accidents over the 12 months prior to the survey. Bivariate and multivariate analyses by means of logistic regression were carried ou...

  20. Association of GPs' risk attitudes, level of empathy, and burnout status with PSA testing in primary care

    DEFF Research Database (Denmark)

    Pedersen, Anette F; Carlsen, Anders H; Vedsted, Peter

    2015-01-01

    Denne artikel undersøger, om variationen i raten af PSA-tests mellem alment praktiserende læger kan forklares af psykologiske faktorer som f.eks. lægens risikovillighed. Resultaterne viser, at lægens risikovillighed influerer på raten af PSA-tests. Forfatterne finder blandt andet, at patienter, s...