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Sample records for random sampling variation

  1. Variational Infinite Hidden Conditional Random Fields.

    Science.gov (United States)

    Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja; Ghahramani, Zoubin

    2015-09-01

    Hidden conditional random fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An Infinite hidden conditional random field is a hidden conditional random field with a countably infinite number of hidden states, which rids us not only of the necessity to specify a priori a fixed number of hidden states available but also of the problem of overfitting. Markov chain Monte Carlo (MCMC) sampling algorithms are often employed for inference in such models. However, convergence of such algorithms is rather difficult to verify, and as the complexity of the task at hand increases the computational cost of such algorithms often becomes prohibitive. These limitations can be overcome by variational techniques. In this paper, we present a generalized framework for infinite HCRF models, and a novel variational inference approach on a model based on coupled Dirichlet Process Mixtures, the HCRF-DPM. We show that the variational HCRF-DPM is able to converge to a correct number of represented hidden states, and performs as well as the best parametric HCRFs-chosen via cross-validation-for the difficult tasks of recognizing instances of agreement, disagreement, and pain in audiovisual sequences.

  2. Incorporating models of spatial variation in sampling strategies for soil

    NARCIS (Netherlands)

    Brus, D.J.

    1993-01-01

    The efficiency of soil sampling strategies can be increased by incorporating a spatial variation model. The model can be used in the random selection of sample points i.e. in the sampling design, or in spatial estimation (prediction). In the first approach inference is based on a sampling

  3. Sunspot random walk and 22-year variation

    Science.gov (United States)

    Love, Jeffrey J.; Rigler, E. Joshua

    2012-01-01

    We examine two stochastic models for consistency with observed long-term secular trends in sunspot number and a faint, but semi-persistent, 22-yr signal: (1) a null hypothesis, a simple one-parameter random-walk model of sunspot-number cycle-to-cycle change, and, (2) an alternative hypothesis, a two-parameter random-walk model with an imposed 22-yr alternating amplitude. The observed secular trend in sunspots, seen from solar cycle 5 to 23, would not be an unlikely result of the accumulation of multiple random-walk steps. Statistical tests show that a 22-yr signal can be resolved in historical sunspot data; that is, the probability is low that it would be realized from random data. On the other hand, the 22-yr signal has a small amplitude compared to random variation, and so it has a relatively small effect on sunspot predictions. Many published predictions for cycle 24 sunspots fall within the dispersion of previous cycle-to-cycle sunspot differences. The probability is low that the Sun will, with the accumulation of random steps over the next few cycles, walk down to a Dalton-like minimum. Our models support published interpretations of sunspot secular variation and 22-yr variation resulting from cycle-to-cycle accumulation of dynamo-generated magnetic energy.

  4. k-Means: Random Sampling Procedure

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. k-Means: Random Sampling Procedure. Optimal 1-Mean is. Approximation of Centroid (Inaba et al). S = random sample of size O(1/ ); Centroid of S is a (1+ )-approx centroid of P with constant probability.

  5. Variational data assimilation using targetted random walks

    KAUST Repository

    Cotter, S. L.

    2011-02-15

    The variational approach to data assimilation is a widely used methodology for both online prediction and for reanalysis. In either of these scenarios, it can be important to assess uncertainties in the assimilated state. Ideally, it is desirable to have complete information concerning the Bayesian posterior distribution for unknown state given data. We show that complete computational probing of this posterior distribution is now within the reach in the offline situation. We introduce a Markov chain-Monte Carlo (MCMC) method which enables us to directly sample from the Bayesian posterior distribution on the unknown functions of interest given observations. Since we are aware that these methods are currently too computationally expensive to consider using in an online filtering scenario, we frame this in the context of offline reanalysis. Using a simple random walk-type MCMC method, we are able to characterize the posterior distribution using only evaluations of the forward model of the problem, and of the model and data mismatch. No adjoint model is required for the method we use; however, more sophisticated MCMC methods are available which exploit derivative information. For simplicity of exposition, we consider the problem of assimilating data, either Eulerian or Lagrangian, into a low Reynolds number flow in a two-dimensional periodic geometry. We will show that in many cases it is possible to recover the initial condition and model error (which we describe as unknown forcing to the model) from data, and that with increasing amounts of informative data, the uncertainty in our estimations reduces. © 2011 John Wiley & Sons, Ltd.

  6. K-Median: Random Sampling Procedure

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. K-Median: Random Sampling Procedure. Sample a set of 1/ + 1 points from P. Let Q = first 1/ points, p = last point. Let T = Avg. 1-Median cost of P, c=1-Median. Let B1 = B(c,T/ 2), B2 = B(p, T). Let P' = points in B1.

  7. Acceptance sampling using judgmental and randomly selected samples

    Energy Technology Data Exchange (ETDEWEB)

    Sego, Landon H.; Shulman, Stanley A.; Anderson, Kevin K.; Wilson, John E.; Pulsipher, Brent A.; Sieber, W. Karl

    2010-09-01

    We present a Bayesian model for acceptance sampling where the population consists of two groups, each with different levels of risk of containing unacceptable items. Expert opinion, or judgment, may be required to distinguish between the high and low-risk groups. Hence, high-risk items are likely to be identifed (and sampled) using expert judgment, while the remaining low-risk items are sampled randomly. We focus on the situation where all observed samples must be acceptable. Consequently, the objective of the statistical inference is to quantify the probability that a large percentage of the unsampled items in the population are also acceptable. We demonstrate that traditional (frequentist) acceptance sampling and simpler Bayesian formulations of the problem are essentially special cases of the proposed model. We explore the properties of the model in detail, and discuss the conditions necessary to ensure that required samples sizes are non-decreasing function of the population size. The method is applicable to a variety of acceptance sampling problems, and, in particular, to environmental sampling where the objective is to demonstrate the safety of reoccupying a remediated facility that has been contaminated with a lethal agent.

  8. Variational Infinite Hidden Conditional Random Fields

    NARCIS (Netherlands)

    Bousmalis, Konstantinos; Zafeiriou, Stefanos; Morency, Louis-Philippe; Pantic, Maja; Ghahramani, Zoubin

    2015-01-01

    Hidden conditional random fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An Infinite hidden conditional random field is a hidden conditional random field with a countably infinite number of

  9. GSAMPLE: Stata module to draw a random sample

    OpenAIRE

    Jann, Ben

    2006-01-01

    gsample draws a random sample from the data in memory. Simple random sampling (SRS) is supported, as well as unequal probability sampling (UPS), of which sampling with probabilities proportional to size (PPS) is a special case. Both methods, SRS and UPS/PPS, provide sampling with replacement and sampling without replacement. Furthermore, stratified sampling and cluster sampling is supported.

  10. Generation and Analysis of Constrained Random Sampling Patterns

    DEFF Research Database (Denmark)

    Pierzchlewski, Jacek; Arildsen, Thomas

    2016-01-01

    Random sampling is a technique for signal acquisition which is gaining popularity in practical signal processing systems. Nowadays, event-driven analog-to-digital converters make random sampling feasible in practical applications. A process of random sampling is defined by a sampling pattern, whi...

  11. Analysis of a global random stratified sample of nurse legislation.

    Science.gov (United States)

    Benton, D C; Fernández-Fernández, M P; González-Jurado, M A; Beneit-Montesinos, J V

    2015-06-01

    To identify, compare and contrast the major component parts of heterogeneous stratified sample of nursing legislation. Nursing legislation varies from one jurisdiction to another. Up until now no research exists into whether the variations of such legislation are random or if variations are related to a set of key attributes. This mixed method study used a random stratified sample of legislation to map through documentary analysis the content of 14 nursing acts and then explored, using quantitative techniques, whether the material contained relates to a number of key attributes. These attributes include: legal tradition of the jurisdiction; model of regulation; administrative approach; area of the world; and the economic status of the jurisdiction. Twelve component parts of nursing legislation were identified. These were remarkably similar irrespective of attributes of interest. However, not all component parts were specified in the same level of detail and the manner by which the elements were addressed did vary. A number of potential relationships between the structure of the legislation and the key attributes of interest were identified. This study generated a comprehensive and integrated map of a global sample of nursing legislation. It provides a set of descriptors to be used to undertake further quantitative work and provides an important policy tool to facilitate dialogue between regulatory bodies. At the individual nurse level it offers insights that can help nurses pursue recognition of credentials across jurisdictions. © 2015 International Council of Nurses.

  12. A random spatial sampling method in a rural developing nation

    Science.gov (United States)

    Michelle C. Kondo; Kent D.W. Bream; Frances K. Barg; Charles C. Branas

    2014-01-01

    Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method...

  13. Power Spectrum Estimation of Randomly Sampled Signals

    DEFF Research Database (Denmark)

    Velte, Clara M.; Buchhave, Preben; K. George, William

    2014-01-01

    with high data rate and low inherent bias, respectively, while residence time weighting provides non-biased estimates regardless of setting. The free-running processor was also tested and compared to residence time weighting using actual LDA measurements in a turbulent round jet. Power spectra from...... of alternative methods attempting to produce correct power spectra have been invented andtested. The objective of the current study is to create a simple computer generated signal for baseline testing of residence time weighting and some of the most commonly proposed algorithms (or algorithms which most...... modernalgorithms ultimately are based on), sample-and-hold and the direct spectral estimator without residence time weighting, and compare how they perform in relation to power spectra based on the equidistantly sampled reference signal. The computer generated signal is a Poisson process with a sample rate...

  14. Random constraint sampling and duality for convex optimization

    OpenAIRE

    Haskell, William B.; Pengqian, Yu

    2016-01-01

    We are interested in solving convex optimization problems with large numbers of constraints. Randomized algorithms, such as random constraint sampling, have been very successful in giving nearly optimal solutions to such problems. In this paper, we combine random constraint sampling with the classical primal-dual algorithm for convex optimization problems with large numbers of constraints, and we give a convergence rate analysis. We then report numerical experiments that verify the effectiven...

  15. Random number datasets generated from statistical analysis of randomly sampled GSM recharge cards.

    Science.gov (United States)

    Okagbue, Hilary I; Opanuga, Abiodun A; Oguntunde, Pelumi E; Ugwoke, Paulinus O

    2017-02-01

    In this article, a random number of datasets was generated from random samples of used GSM (Global Systems for Mobile Communications) recharge cards. Statistical analyses were performed to refine the raw data to random number datasets arranged in table. A detailed description of the method and relevant tests of randomness were also discussed.

  16. Power Spectrum Estimation of Randomly Sampled Signals

    DEFF Research Database (Denmark)

    Velte, C. M.; Buchhave, P.; K. George, W.

    . Residence time weighting provides non-biased estimates regardless of setting. The free-running processor was also tested and compared to residence time weighting using actual LDA measurements in a turbulent round jet. Power spectra from measurements on the jet centerline and the outer part of the jet...... sine waves. The primary signal and the corresponding power spectrum are shown in Figure 1. The conventional spectrum shows multiple erroneous mixing frequencies and the peak values are too low. The residence time weighted spectrum is correct. The sample-and-hold spectrum has lower power than...... the correct spectrum, and the f -2-filtering effect appearing for low data densities is evident (Adrian and Yao 1987). The remaining tests also show that sample-and-hold and the free-running processor perform well only under very particular circumstances with high data rate and low inherent bias, respectively...

  17. Manifolds in random media: beyond the variational approximation

    Science.gov (United States)

    Goldschmidt, Yadin Y.

    1994-01-01

    In this paper we give a closed form expression for the 1/d corrections to the selfenergy characterizing the correlation function of a manifold in random media. This amounts to the first confection beyond the variational approximation. At this time we were able to evaluate these corrections in the high temperature "phase" of the notorious toy-model describing a classical particle subject to the influence of both a harmonic potential and a random potential. Although in this phase the correct solution is replica symmetric the calculation is non-trivial. The outcome is compared with previous analytical and numerical results. The corrections diverge at the "transition" temperature.

  18. Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling.

    Science.gov (United States)

    Biro, Peter A

    2013-02-01

    Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, 'hidden' trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

  19. Random noise attenuation using an improved anisotropic total variation regularization

    Science.gov (United States)

    Gemechu, Diriba; Yuan, Huan; Ma, Jianwei

    2017-09-01

    In seismic data processing, attenuation of random noise from the observed data is the basic step which improves the signal-to-noise ratio (SNR) of seismic data. In this paper, we proposed an anisotropic total bounded variation regularization approach to attenuate noise. An improved constraint convex optimization model is formulated for this approach and then the split Bregman algorithm is used to solve the optimization model. Generalized cross validation (GCV) technique is used to estimate the regularization parameter. Synthetic and real seismic data are considered to show the out performance of the proposed method in terms of event-preserving denoising, in comparison with FX deconvolution, shearlet hard thresholding, and anisotropic total variation methods. The numerical results indicate that the proposed method effectively attenuates random noise by preserving the structure and important features of seismic data.

  20. SOME SYSTEMATIC SAMPLING STRATEGIES USING MULTIPLE RANDOM STARTS

    Directory of Open Access Journals (Sweden)

    Sampath Sundaram

    2010-09-01

    Full Text Available In this paper an attempt is made to extend linear systematic sampling using multiple random starts due to Gautschi(1957for various types of systematic sampling schemes available in literature, namely(i  Balanced Systematic Sampling (BSS of  Sethi (1965 and (ii Modified Systematic Sampling (MSS of Singh, Jindal, and Garg  (1968. Further, the proposed methods were compared with Yates corrected estimator developed with reference to Gautschi’s Linear systematic sampling (LSS with two random starts using appropriate super population models with the  help of R package for statistical computing.

  1. Efficient sampling of complex network with modified random walk strategies

    Science.gov (United States)

    Xie, Yunya; Chang, Shuhua; Zhang, Zhipeng; Zhang, Mi; Yang, Lei

    2018-02-01

    We present two novel random walk strategies, choosing seed node (CSN) random walk and no-retracing (NR) random walk. Different from the classical random walk sampling, the CSN and NR strategies focus on the influences of the seed node choice and path overlap, respectively. Three random walk samplings are applied in the Erdös-Rényi (ER), Barabási-Albert (BA), Watts-Strogatz (WS), and the weighted USAir networks, respectively. Then, the major properties of sampled subnets, such as sampling efficiency, degree distributions, average degree and average clustering coefficient, are studied. The similar conclusions can be reached with these three random walk strategies. Firstly, the networks with small scales and simple structures are conducive to the sampling. Secondly, the average degree and the average clustering coefficient of the sampled subnet tend to the corresponding values of original networks with limited steps. And thirdly, all the degree distributions of the subnets are slightly biased to the high degree side. However, the NR strategy performs better for the average clustering coefficient of the subnet. In the real weighted USAir networks, some obvious characters like the larger clustering coefficient and the fluctuation of degree distribution are reproduced well by these random walk strategies.

  2. Spatial Random Sampling: A Structure-Preserving Data Sketching Tool

    Science.gov (United States)

    Rahmani, Mostafa; Atia, George K.

    2017-09-01

    Random column sampling is not guaranteed to yield data sketches that preserve the underlying structures of the data and may not sample sufficiently from less-populated data clusters. Also, adaptive sampling can often provide accurate low rank approximations, yet may fall short of producing descriptive data sketches, especially when the cluster centers are linearly dependent. Motivated by that, this paper introduces a novel randomized column sampling tool dubbed Spatial Random Sampling (SRS), in which data points are sampled based on their proximity to randomly sampled points on the unit sphere. The most compelling feature of SRS is that the corresponding probability of sampling from a given data cluster is proportional to the surface area the cluster occupies on the unit sphere, independently from the size of the cluster population. Although it is fully randomized, SRS is shown to provide descriptive and balanced data representations. The proposed idea addresses a pressing need in data science and holds potential to inspire many novel approaches for analysis of big data.

  3. Methods for sample size determination in cluster randomized trials.

    Science.gov (United States)

    Rutterford, Clare; Copas, Andrew; Eldridge, Sandra

    2015-06-01

    The use of cluster randomized trials (CRTs) is increasing, along with the variety in their design and analysis. The simplest approach for their sample size calculation is to calculate the sample size assuming individual randomization and inflate this by a design effect to account for randomization by cluster. The assumptions of a simple design effect may not always be met; alternative or more complicated approaches are required. We summarise a wide range of sample size methods available for cluster randomized trials. For those familiar with sample size calculations for individually randomized trials but with less experience in the clustered case, this manuscript provides formulae for a wide range of scenarios with associated explanation and recommendations. For those with more experience, comprehensive summaries are provided that allow quick identification of methods for a given design, outcome and analysis method. We present first those methods applicable to the simplest two-arm, parallel group, completely randomized design followed by methods that incorporate deviations from this design such as: variability in cluster sizes; attrition; non-compliance; or the inclusion of baseline covariates or repeated measures. The paper concludes with methods for alternative designs. There is a large amount of methodology available for sample size calculations in CRTs. This paper gives the most comprehensive description of published methodology for sample size calculation and provides an important resource for those designing these trials. © The Author 2015. Published by Oxford University Press on behalf of the International Epidemiological Association.

  4. SOME SYSTEMATIC SAMPLING STRATEGIES USING MULTIPLE RANDOM STARTS

    OpenAIRE

    Sampath Sundaram; Ammani Sivaraman

    2010-01-01

    In this paper an attempt is made to extend linear systematic sampling using multiple random starts due to Gautschi(1957)for various types of systematic sampling schemes available in literature, namely(i)  Balanced Systematic Sampling (BSS) of  Sethi (1965) and (ii) Modified Systematic Sampling (MSS) of Singh, Jindal, and Garg  (1968). Further, the proposed methods were compared with Yates corrected estimator developed with reference to Gautschi’s Linear systematic samplin...

  5. Sampling large random knots in a confined space

    Energy Technology Data Exchange (ETDEWEB)

    Arsuaga, J [Department of Mathematics, San Francisco State University, 1600 Holloway Ave, San Francisco, CA 94132 (United States); Blackstone, T [Department of Computer Science, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132 (United States); Diao, Y [Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Hinson, K [Department of Mathematics and Statistics, University of North Carolina at Charlotte, Charlotte, NC 28223 (United States); Karadayi, E [Department of Mathematics, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620 (United States); Saito, M [Department of Mathematics, University of South Florida, 4202 E Fowler Avenue, Tampa, FL 33620 (United States)

    2007-09-28

    DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e{sup n{sup 2}}). We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n{sup 2}). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications.

  6. Variational Calculation of Effective Parameters in Random Porous Media

    Science.gov (United States)

    Hristopulos, Dionissios T.; Christakos, George

    1998-03-01

    Effective parameters are used in stochastic hydrology and petroleum engineering as estimates of the coarse-grained behavior of fluid flow and transport. Stochastic effective parameter estimation involves averaging over the local heterogeneity. Explicit evaluation methods are often based on low order perturbation expansions. We obtain more general estimates using a variational scheme that employs auxiliary probability measures. The average over the local fluctuations is evaluated by means of the logarithm transform and the replica trick. The equations satisfied by the effective parameters are obtained variationally from an effective free energy functional. We use this method for the evaluation of the effective permeability of random porous media with Gaussian local fluctuations. The resulting equations are solved explicitly in specific cases, and the results are compared with leading-order perturbation estimates and experimental data. Explicit finite-size expressions are obtained using momentum-space filters. The implications of the finite size behavior for the scaleup problem are discussed.

  7. Sequential time interleaved random equivalent sampling for repetitive signal

    Science.gov (United States)

    Zhao, Yijiu; Liu, Jingjing

    2016-12-01

    Compressed sensing (CS) based sampling techniques exhibit many advantages over other existing approaches for sparse signal spectrum sensing; they are also incorporated into non-uniform sampling signal reconstruction to improve the efficiency, such as random equivalent sampling (RES). However, in CS based RES, only one sample of each acquisition is considered in the signal reconstruction stage, and it will result in more acquisition runs and longer sampling time. In this paper, a sampling sequence is taken in each RES acquisition run, and the corresponding block measurement matrix is constructed using a Whittaker-Shannon interpolation formula. All the block matrices are combined into an equivalent measurement matrix with respect to all sampling sequences. We implemented the proposed approach with a multi-cores analog-to-digital converter (ADC), whose ADC cores are time interleaved. A prototype realization of this proposed CS based sequential random equivalent sampling method has been developed. It is able to capture an analog waveform at an equivalent sampling rate of 40 GHz while sampled at 1 GHz physically. Experiments indicate that, for a sparse signal, the proposed CS based sequential random equivalent sampling exhibits high efficiency.

  8. A practical guide and power analysis for GLMMs: detecting among treatment variation in random effects.

    Science.gov (United States)

    Kain, Morgan P; Bolker, Ben M; McCoy, Michael W

    2015-01-01

    In ecology and evolution generalized linear mixed models (GLMMs) are becoming increasingly used to test for differences in variation by treatment at multiple hierarchical levels. Yet, the specific sampling schemes that optimize the power of an experiment to detect differences in random effects by treatment/group remain unknown. In this paper we develop a blueprint for conducting power analyses for GLMMs focusing on detecting differences in variance by treatment. We present parameterization and power analyses for random-intercepts and random-slopes GLMMs because of their generality as focal parameters for most applications and because of their immediate applicability to emerging questions in the field of behavioral ecology. We focus on the extreme case of hierarchically structured binomial data, though the framework presented here generalizes easily to any error distribution model. First, we determine the optimal ratio of individuals to repeated measures within individuals that maximizes power to detect differences by treatment in among-individual variation in intercept, among-individual variation in slope, and within-individual variation in intercept. Second, we explore how power to detect differences in target variance parameters is affected by total variation. Our results indicate heterogeneity in power across ratios of individuals to repeated measures with an optimal ratio determined by both the target variance parameter and total sample size. Additionally, power to detect each variance parameter was low overall (in most cases >1,000 total observations per treatment needed to achieve 80% power) and decreased with increasing variance in non-target random effects. With growing interest in variance as the parameter of inquiry, these power analyses provide a crucial component for designing experiments focused on detecting differences in variance. We hope to inspire novel experimental designs in ecology and evolution investigating the causes and implications of

  9. Optimum allocation in multivariate stratified random sampling: Stochastic matrix optimisation

    OpenAIRE

    Diaz-Garcia, Jose A.; Ramos-Quiroga, Rogelio

    2011-01-01

    The allocation problem for multivariate stratified random sampling as a problem of stochastic matrix integer mathematical programming is considered. With these aims the asymptotic normality of sample covariance matrices for each strata is established. Some alternative approaches are suggested for its solution. An example is solved by applying the proposed techniques.

  10. Performance of Random Effects Model Estimators under Complex Sampling Designs

    Science.gov (United States)

    Jia, Yue; Stokes, Lynne; Harris, Ian; Wang, Yan

    2011-01-01

    In this article, we consider estimation of parameters of random effects models from samples collected via complex multistage designs. Incorporation of sampling weights is one way to reduce estimation bias due to unequal probabilities of selection. Several weighting methods have been proposed in the literature for estimating the parameters of…

  11. Random matrix approach to the dynamics of stock inventory variations

    Science.gov (United States)

    Zhou, Wei-Xing; Mu, Guo-Hua; Kertész, János

    2012-09-01

    It is well accepted that investors can be classified into groups owing to distinct trading strategies, which forms the basic assumption of many agent-based models for financial markets when agents are not zero-intelligent. However, empirical tests of these assumptions are still very rare due to the lack of order flow data. Here we adopt the order flow data of Chinese stocks to tackle this problem by investigating the dynamics of inventory variations for individual and institutional investors that contain rich information about the trading behavior of investors and have a crucial influence on price fluctuations. We find that the distributions of cross-correlation coefficient Cij have power-law forms in the bulk that are followed by exponential tails, and there are more positive coefficients than negative ones. In addition, it is more likely that two individuals or two institutions have a stronger inventory variation correlation than one individual and one institution. We find that the largest and the second largest eigenvalues (λ1 and λ2) of the correlation matrix cannot be explained by random matrix theory and the projections of investors' inventory variations on the first eigenvector u(λ1) are linearly correlated with stock returns, where individual investors play a dominating role. The investors are classified into three categories based on the cross-correlation coefficients CV R between inventory variations and stock returns. A strong Granger causality is unveiled from stock returns to inventory variations, which means that a large proportion of individuals hold the reversing trading strategy and a small part of individuals hold the trending strategy. Our empirical findings have scientific significance in the understanding of investors' trading behavior and in the construction of agent-based models for emerging stock markets.

  12. A random spatial sampling method in a rural developing nation.

    Science.gov (United States)

    Kondo, Michelle C; Bream, Kent D W; Barg, Frances K; Branas, Charles C

    2014-04-10

    Nonrandom sampling of populations in developing nations has limitations and can inaccurately estimate health phenomena, especially among hard-to-reach populations such as rural residents. However, random sampling of rural populations in developing nations can be challenged by incomplete enumeration of the base population. We describe a stratified random sampling method using geographical information system (GIS) software and global positioning system (GPS) technology for application in a health survey in a rural region of Guatemala, as well as a qualitative study of the enumeration process. This method offers an alternative sampling technique that could reduce opportunities for bias in household selection compared to cluster methods. However, its use is subject to issues surrounding survey preparation, technological limitations and in-the-field household selection. Application of this method in remote areas will raise challenges surrounding the boundary delineation process, use and translation of satellite imagery between GIS and GPS, and household selection at each survey point in varying field conditions. This method favors household selection in denser urban areas and in new residential developments. Random spatial sampling methodology can be used to survey a random sample of population in a remote region of a developing nation. Although this method should be further validated and compared with more established methods to determine its utility in social survey applications, it shows promise for use in developing nations with resource-challenged environments where detailed geographic and human census data are less available.

  13. Sample Selection in Randomized Experiments: A New Method Using Propensity Score Stratified Sampling

    Science.gov (United States)

    Tipton, Elizabeth; Hedges, Larry; Vaden-Kiernan, Michael; Borman, Geoffrey; Sullivan, Kate; Caverly, Sarah

    2014-01-01

    Randomized experiments are often seen as the "gold standard" for causal research. Despite the fact that experiments use random assignment to treatment conditions, units are seldom selected into the experiment using probability sampling. Very little research on experimental design has focused on how to make generalizations to well-defined…

  14. Seismic random noise attenuation using shearlet and total generalized variation

    Science.gov (United States)

    Kong, Dehui; Peng, Zhenming

    2015-12-01

    Seismic denoising from a corrupted observation is an important part of seismic data processing which improves the signal-to-noise ratio (SNR) and resolution. In this paper, we present an effective denoising method to attenuate seismic random noise. The method takes advantage of shearlet and total generalized variation (TGV) regularization. Different regularity levels of TGV improve the quality of the final result by suppressing Gibbs artifacts caused by the shearlet. The problem is formulated as mixed constraints in a convex optimization. A Bregman algorithm is proposed to solve the proposed model. Extensive experiments based on one synthetic datum and two post-stack field data are done to compare performance. The results demonstrate that the proposed method provides superior effectiveness and preserve the structure better.

  15. Comparison of kriging interpolation precision between grid sampling scheme and simple random sampling scheme for precision agriculture

    Directory of Open Access Journals (Sweden)

    Jiang Houlong

    2016-01-01

    Full Text Available Sampling methods are important factors that can potentially limit the accuracy of predictions of spatial distribution patterns. A 10 ha tobacco-planted field was selected to compared the accuracy in predicting the spatial distribution of soil properties by using ordinary kriging and cross validation methods between grid sampling and simple random sampling scheme (SRS. To achieve this objective, we collected soil samples from the topsoil (0-20 cm in March 2012. Sample numbers of grid sampling and SRS were both 115 points each. Accuracies of spatial interpolation using the two sampling schemes were then evaluated based on validation samples (36 points and deviations of the estimates. The results suggested that soil pH and nitrate-N (NO3-N had low variation, whereas all other soil properties exhibited medium variation. Soil pH, organic matter (OM, total nitrogen (TN, cation exchange capacity (CEC, total phosphorus (TP and available phosphorus (AP matched the spherical model, whereas the remaining variables fit an exponential model with both sampling methods. The interpolation error of soil pH, TP, and AP was the lowest in SRS. The errors of interpolation for OM, CEC, TN, available potassium (AK and total potassium (TK were the lowest for grid sampling. The interpolation precisions of the soil NO3-N showed no significant differences between the two sampling schemes. Considering our data on interpolation precision and the importance of minerals for cultivation of flue-cured tobacco, the grid-sampling scheme should be used in tobacco-planted fields to determine the spatial distribution of soil properties. The grid-sampling method can be applied in a practical and cost-effective manner to facilitate soil sampling in tobacco-planted field.

  16. Random sampling and validation of covariance matrices of resonance parameters

    Science.gov (United States)

    Plevnik, Lucijan; Zerovnik, Gašper

    2017-09-01

    Analytically exact methods for random sampling of arbitrary correlated parameters are presented. Emphasis is given on one hand on the possible inconsistencies in the covariance data, concentrating on the positive semi-definiteness and consistent sampling of correlated inherently positive parameters, and on the other hand on optimization of the implementation of the methods itself. The methods have been applied in the program ENDSAM, written in the Fortran language, which from a file from a nuclear data library of a chosen isotope in ENDF-6 format produces an arbitrary number of new files in ENDF-6 format which contain values of random samples of resonance parameters (in accordance with corresponding covariance matrices) in places of original values. The source code for the program ENDSAM is available from the OECD/NEA Data Bank. The program works in the following steps: reads resonance parameters and their covariance data from nuclear data library, checks whether the covariance data is consistent, and produces random samples of resonance parameters. The code has been validated with both realistic and artificial data to show that the produced samples are statistically consistent. Additionally, the code was used to validate covariance data in existing nuclear data libraries. A list of inconsistencies, observed in covariance data of resonance parameters in ENDF-VII.1, JEFF-3.2 and JENDL-4.0 is presented. For now, the work has been limited to resonance parameters, however the methods presented are general and can in principle be extended to sampling and validation of any nuclear data.

  17. Generalized and synthetic regression estimators for randomized branch sampling

    Science.gov (United States)

    David L. R. Affleck; Timothy G. Gregoire

    2015-01-01

    In felled-tree studies, ratio and regression estimators are commonly used to convert more readily measured branch characteristics to dry crown mass estimates. In some cases, data from multiple trees are pooled to form these estimates. This research evaluates the utility of both tactics in the estimation of crown biomass following randomized branch sampling (...

  18. Effective sampling of random surfaces by baby universe surgery

    NARCIS (Netherlands)

    Ambjørn, J.; Białas, P.; Jurkiewicz, J.; Burda, Z.; Petersson, B.

    1994-01-01

    We propose a new, very efficient algorithm for sampling of random surfaces in the Monte Carlo simulations, based on so-called baby universe surgery, i.e. cutting and pasting of baby universe. It drastically reduces slowing down as compared to the standard local flip algorithm, thereby allowing

  19. Application of variational mode decomposition to seismic random noise reduction

    Science.gov (United States)

    Liu, Wei; Cao, Siyuan; Wang, Zhiming

    2017-08-01

    We have proposed a new denoising method for the simultaneous noise reduction and preservation of seismic signals based on variational mode decomposition (VMD). VMD is a recently developed adaptive signal decomposition method and an advance in non-stationary signal analysis. It solves the mode-mixing and non-optimal reconstruction performance problems of empirical mode decomposition that have existed for a long time. By using VMD, a multi-component signal can be non-recursively decomposed into a series of quasi-orthogonal intrinsic mode functions (IMFs), each of which has a relatively local frequency range. Meanwhile, the signal will focus on a smaller number of obtained IMFs after decomposition, and thus the denoised result is able to be obtained by reconstructing these signal-dominant IMFs. Synthetic examples are given to demonstrate the effectiveness of the proposed approach and comparison is made with the complete ensemble empirical mode decomposition, which demonstrates that the VMD algorithm has lower computational cost and better random noise elimination performance. The application of on field seismic data further illustrates the superior performance of our method in both random noise attenuation and the recovery of seismic events.

  20. Maximizing the reliability of non-invasive endocrine sampling in the tiger (Panthera tigris): environmental decay and intra-sample variation in faecal glucocorticoid metabolites.

    Science.gov (United States)

    Parnell, Tempe; Narayan, Edward J; Nicolson, Vere; Martin-Vegue, Patrick; Mucci, Al; Hero, Jean-Marc

    2015-01-01

    Evaluation of physiological stress in the tiger (Panthera tigris) using faecal cortisol metabolite (FCM) enzyme immunoassays (EIAs) provides a powerful conservation physiology tool for the species. However, it is important to validate non-invasive endocrine sampling techniques in field conditions to ensure that the method provides a reliable parameter of physiological stress in the species. This is because endocrine measurements are highly species specific and FCM concentrations can be influenced by environmental factors. Here, we studied the impact of the decay rate of FCMs and intra-sample variation of FCMs using a previously validated EIA. To determine the decay rate of FCMs, we measured FCMs in freshly deposited tiger faeces (n = 8 tigers and 48 scats) that were randomly exposed to the natural environment (dry conditions with no rainfall) for up to 192 h. To determine intra-sample variation in FCMs, we used 10 scats from 10 tigers, divided each sample into four sections and each section into four sub-sections and measured FCMs in each section and sub-section. The results of this decay-rate experiment showed that FCMs in tiger faeces began to decay after 48 h exposure to the environmental conditions available. Thus, FCMs within freshly deposited tiger faeces are influenced by available environmental conditions. Changes in weather conditions (e.g. increased rainfall and humidity) could influence the stability of FCMs. The results of the intra-sample variation study showed that inter-variation among scats accounted for 52% of the variations in FCMs, while intra-sample variation between sections (32%) was greater than the sub-sample variation (16%). Intra-sample variation can be reduced by homogenizing the entire lyophilized faecal sample prior to the EIA. In conclusion, careful evaluation of decay rate and complete homogenization of faeces prior to EIA analysis will increase the reliability of FCMs as a non-invasive index of physiological stress in the

  1. Random sampling and validation of covariance matrices of resonance parameters

    Directory of Open Access Journals (Sweden)

    Plevnik Lucijan

    2017-01-01

    Full Text Available Analytically exact methods for random sampling of arbitrary correlated parameters are presented. Emphasis is given on one hand on the possible inconsistencies in the covariance data, concentrating on the positive semi-definiteness and consistent sampling of correlated inherently positive parameters, and on the other hand on optimization of the implementation of the methods itself. The methods have been applied in the program ENDSAM, written in the Fortran language, which from a file from a nuclear data library of a chosen isotope in ENDF-6 format produces an arbitrary number of new files in ENDF-6 format which contain values of random samples of resonance parameters (in accordance with corresponding covariance matrices in places of original values. The source code for the program ENDSAM is available from the OECD/NEA Data Bank. The program works in the following steps: reads resonance parameters and their covariance data from nuclear data library, checks whether the covariance data is consistent, and produces random samples of resonance parameters. The code has been validated with both realistic and artificial data to show that the produced samples are statistically consistent. Additionally, the code was used to validate covariance data in existing nuclear data libraries. A list of inconsistencies, observed in covariance data of resonance parameters in ENDF-VII.1, JEFF-3.2 and JENDL-4.0 is presented. For now, the work has been limited to resonance parameters, however the methods presented are general and can in principle be extended to sampling and validation of any nuclear data.

  2. Hierarchical Protein Free Energy Landscapes from Variationally Enhanced Sampling.

    Science.gov (United States)

    Shaffer, Patrick; Valsson, Omar; Parrinello, Michele

    2016-12-13

    In recent work, we demonstrated that it is possible to obtain approximate representations of high-dimensional free energy surfaces with variationally enhanced sampling ( Shaffer, P.; Valsson, O.; Parrinello, M. Proc. Natl. Acad. Sci. , 2016 , 113 , 17 ). The high-dimensional spaces considered in that work were the set of backbone dihedral angles of a small peptide, Chignolin, and the high-dimensional free energy surface was approximated as the sum of many two-dimensional terms plus an additional term which represents an initial estimate. In this paper, we build on that work and demonstrate that we can calculate high-dimensional free energy surfaces of very high accuracy by incorporating additional terms. The additional terms apply to a set of collective variables which are more coarse than the base set of collective variables. In this way, it is possible to build hierarchical free energy surfaces, which are composed of terms that act on different length scales. We test the accuracy of these free energy landscapes for the proteins Chignolin and Trp-cage by constructing simple coarse-grained models and comparing results from the coarse-grained model to results from atomistic simulations. The approach described in this paper is ideally suited for problems in which the free energy surface has important features on different length scales or in which there is some natural hierarchy.

  3. Sampling Polymorphs of Ionic Solids using Random Superlattices.

    Science.gov (United States)

    Stevanović, Vladan

    2016-02-19

    Polymorphism offers rich and virtually unexplored space for discovering novel functional materials. To harness this potential approaches capable of both exploring the space of polymorphs and assessing their realizability are needed. One such approach devised for partially ionic solids is presented. The structure prediction part is carried out by performing local density functional theory relaxations on a large set of random supperlattices (RSLs) with atoms distributed randomly over different planes in a way that favors cation-anion coordination. Applying the RSL sampling on MgO, ZnO, and SnO_{2} reveals that the resulting probability of occurrence of a given structure offers a measure of its realizability explaining fully the experimentally observed, metastable polymorphs in these three systems.

  4. Variation in rank abundance replicate samples and impact of clustering

    NARCIS (Netherlands)

    Neuteboom, J.H.; Struik, P.C.

    2005-01-01

    Calculating a single-sample rank abundance curve by using the negative-binomial distribution provides a way to investigate the variability within rank abundance replicate samples and yields a measure of the degree of heterogeneity of the sampled community. The calculation of the single-sample rank

  5. Randomly Sampled-Data Control Systems. Ph.D. Thesis

    Science.gov (United States)

    Han, Kuoruey

    1990-01-01

    The purpose is to solve the Linear Quadratic Regulator (LQR) problem with random time sampling. Such a sampling scheme may arise from imperfect instrumentation as in the case of sampling jitter. It can also model the stochastic information exchange among decentralized controllers to name just a few. A practical suboptimal controller is proposed with the nice property of mean square stability. The proposed controller is suboptimal in the sense that the control structure is limited to be linear. Because of i. i. d. assumption, this does not seem unreasonable. Once the control structure is fixed, the stochastic discrete optimal control problem is transformed into an equivalent deterministic optimal control problem with dynamics described by the matrix difference equation. The N-horizon control problem is solved using the Lagrange's multiplier method. The infinite horizon control problem is formulated as a classical minimization problem. Assuming existence of solution to the minimization problem, the total system is shown to be mean square stable under certain observability conditions. Computer simulations are performed to illustrate these conditions.

  6. A Table-Based Random Sampling Simulation for Bioluminescence Tomography

    Directory of Open Access Journals (Sweden)

    Xiaomeng Zhang

    2006-01-01

    Full Text Available As a popular simulation of photon propagation in turbid media, the main problem of Monte Carlo (MC method is its cumbersome computation. In this work a table-based random sampling simulation (TBRS is proposed. The key idea of TBRS is to simplify multisteps of scattering to a single-step process, through randomly table querying, thus greatly reducing the computing complexity of the conventional MC algorithm and expediting the computation. The TBRS simulation is a fast algorithm of the conventional MC simulation of photon propagation. It retained the merits of flexibility and accuracy of conventional MC method and adapted well to complex geometric media and various source shapes. Both MC simulations were conducted in a homogeneous medium in our work. Also, we present a reconstructing approach to estimate the position of the fluorescent source based on the trial-and-error theory as a validation of the TBRS algorithm. Good agreement is found between the conventional MC simulation and the TBRS simulation.

  7. Size variation in samples of fossil and recent murid teeth

    NARCIS (Netherlands)

    Freudenthal, M.; Martín Suárez, E.

    1990-01-01

    The variability coefficient proposed by Freudenthal & Cuenca Bescós (1984) for samples of fossil cricetid teeth, is calculated for about 200 samples of fossil and recent murid teeth. The results are discussed, and compared with those obtained for the Cricetidae.

  8. Particulate organic nitrates: Sampling and night/day variation

    DEFF Research Database (Denmark)

    Nielsen, T.; Platz, J.; Granby, K.

    1998-01-01

    Atmospheric day and night concentrations of particulate organic nitrates (PON) and several other air pollutants were measured in the summer 1995 over an open-land area in Denmark. The sampling of PON was evaluated comparing 24 h samples with two sets of 12 h samples. These results indicate...... that the observed low contribution of PON to NO, is real and not the result of an extensive loss during the sampling. Empirical relationships between the vapour pressure and chemical formula of organic compounds were established in order to evaluate the gas/particle distribution of organic nitrates. A positive...... correlation between the PON to NO, ratio and the inverse temperature may indicate that the organic nitrates associated with particles also may be present in the gas phase. The deserved day and nighttime levels of PON were of the same magnitude, although the day to night ratio vaned from 0.4 to 4.4. (C) 1998...

  9. A comparison of methods for representing sparsely sampled random quantities.

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Vicente Jose; Swiler, Laura Painton; Urbina, Angel; Mullins, Joshua

    2013-09-01

    This report discusses the treatment of uncertainties stemming from relatively few samples of random quantities. The importance of this topic extends beyond experimental data uncertainty to situations involving uncertainty in model calibration, validation, and prediction. With very sparse data samples it is not practical to have a goal of accurately estimating the underlying probability density function (PDF). Rather, a pragmatic goal is that the uncertainty representation should be conservative so as to bound a specified percentile range of the actual PDF, say the range between 0.025 and .975 percentiles, with reasonable reliability. A second, opposing objective is that the representation not be overly conservative; that it minimally over-estimate the desired percentile range of the actual PDF. The presence of the two opposing objectives makes the sparse-data uncertainty representation problem interesting and difficult. In this report, five uncertainty representation techniques are characterized for their performance on twenty-one test problems (over thousands of trials for each problem) according to these two opposing objectives and other performance measures. Two of the methods, statistical Tolerance Intervals and a kernel density approach specifically developed for handling sparse data, exhibit significantly better overall performance than the others.

  10. Implications of random variation in the Stand Prognosis Model

    Science.gov (United States)

    David A. Hamilton

    1991-01-01

    Although the Stand Prognosis Model has several stochastic components, features have been included in the model in an attempt to minimize run-to-run variation attributable to these stochastic components. This has led many users to assume that comparisons of management alternatives could be made based on a single run of the model for each alternative. Recent analyses...

  11. Variational Hidden Conditional Random Fields with Coupled Dirichlet Process Mixtures

    NARCIS (Netherlands)

    Bousmalis, K.; Zafeiriou, S.; Morency, L.P.; Pantic, Maja; Ghahramani, Z.

    Hidden Conditional Random Fields (HCRFs) are discriminative latent variable models which have been shown to successfully learn the hidden structure of a given classification problem. An infinite HCRF is an HCRF with a countably infinite number of hidden states, which rids us not only of the

  12. Policies Affect Preferences: Evidence from Random Variation in Abortion Jurisprudence

    OpenAIRE

    Chen, Daniel L.; Levonyan, Vardges; Yeh, Susan

    2016-01-01

    Whether policies shift preferences is relevant to policy design. We exploit the random assignment of U.S. federal judges creating geographically local precedent and the fact that judges’ politics, religion, and race predict decision-making in abortion jurisprudence. Instrumenting for abortion jurisprudence with exogenous judicial characteristics, we estimate the impact of abortion jurisprudence on state laws, campaign donations, and abortion attitudes. We verify information transmission in th...

  13. Variations among animals when estimating the undegradable fraction of fiber in forage samples

    Directory of Open Access Journals (Sweden)

    Cláudia Batista Sampaio

    2014-10-01

    Full Text Available The objective of this study was to assess the variability among animals regarding the critical time to estimate the undegradable fraction of fiber (ct using an in situ incubation procedure. Five rumenfistulated Nellore steers were used to estimate the degradation profile of fiber. Animals were fed a standard diet with an 80:20 forage:concentrate ratio. Sugarcane, signal grass hay, corn silage and fresh elephant grass samples were assessed. Samples were put in F57 Ankom® bags and were incubated in the rumens of the animals for 0, 6, 12, 18, 24, 48, 72, 96, 120, 144, 168, 192, 216, 240 and 312 hours. The degradation profiles were interpreted using a mixed non-linear model in which a random effect was associated with the degradation rate. For sugarcane, signal grass hay and corn silage, there were no significant variations among animals regarding the fractional degradation rate of neutral and acid detergent fiber; consequently, the ct required to estimate the undegradable fiber fraction did not vary among animals for those forages. However, a significant variability among animals was found for the fresh elephant grass. The results seem to suggest that the variability among animals regarding the degradation rate of fibrous components can be significant.

  14. Variation of surface water spectral response as a function of in situ sampling technique

    Science.gov (United States)

    Davis, Bruce A.; Hodgson, Michael E.

    1988-01-01

    Tests were carried out to determine the spectral variation contributed by a particular sampling technique. A portable radiometer was used to measure the surface water spectral response. Variation due to the reflectance of objects near the radiometer (i.e., the boat side) during data acquisition was studied. Consideration was also given to the variation due to the temporal nature of the phenomena (i.e., wave activity).

  15. Variation in the Ratio of Strontium-89 to Strontium-90 in Precipitation Samples with Sampling Height

    DEFF Research Database (Denmark)

    Aarkrog, Asker

    1964-01-01

    It was shown that during March–December 1959 (ref. 1) the specific activities of fission products from fall-out in precipitation increased with sampling height. Some evidence was also found for an increase in the ratio 89Sr/90Sr with sampling height, but this increase was not significant (P ~ 90...

  16. LOD score exclusion analyses for candidate QTLs using random population samples.

    Science.gov (United States)

    Deng, Hong-Wen

    2003-11-01

    While extensive analyses have been conducted to test for, no formal analyses have been conducted to test against, the importance of candidate genes as putative QTLs using random population samples. Previously, we developed an LOD score exclusion mapping approach for candidate genes for complex diseases. Here, we extend this LOD score approach for exclusion analyses of candidate genes for quantitative traits. Under this approach, specific genetic effects (as reflected by heritability) and inheritance models at candidate QTLs can be analyzed and if an LOD score is < or = -2.0, the locus can be excluded from having a heritability larger than that specified. Simulations show that this approach has high power to exclude a candidate gene from having moderate genetic effects if it is not a QTL and is robust to population admixture. Our exclusion analysis complements association analysis for candidate genes as putative QTLs in random population samples. The approach is applied to test the importance of Vitamin D receptor (VDR) gene as a potential QTL underlying the variation of bone mass, an important determinant of osteoporosis.

  17. Sample size calculations for 3-level cluster randomized trials

    NARCIS (Netherlands)

    Teerenstra, S.; Moerbeek, M.; Achterberg, T. van; Pelzer, B.J.; Borm, G.F.

    2008-01-01

    BACKGROUND: The first applications of cluster randomized trials with three instead of two levels are beginning to appear in health research, for instance, in trials where different strategies to implement best-practice guidelines are compared. In such trials, the strategy is implemented in health

  18. Sample size calculations for 3-level cluster randomized trials

    NARCIS (Netherlands)

    Teerenstra, S.; Moerbeek, M.; Achterberg, T. van; Pelzer, B.J.; Borm, G.F.

    2008-01-01

    Background The first applications of cluster randomized trials with three instead of two levels are beginning to appear in health research, for instance, in trials where different strategies to implement best-practice guidelines are compared. In such trials, the strategy is implemented in health

  19. Improved estimator of finite population mean using auxiliary attribute in stratified random sampling

    OpenAIRE

    Verma, Hemant K.; Sharma, Prayas; Singh, Rajesh

    2014-01-01

    The present study discuss the problem of estimating the finite population mean using auxiliary attribute in stratified random sampling. In this paper taking the advantage of point bi-serial correlation between the study variable and auxiliary attribute, we have improved the estimation of population mean in stratified random sampling. The expressions for Bias and Mean square error have been derived under stratified random sampling. In addition, an empirical study has been carried out to examin...

  20. A Family of Estimators of a Sensitive Variable Using Auxiliary Information in Stratified Random Sampling

    Directory of Open Access Journals (Sweden)

    Nadia Mushtaq

    2017-03-01

    Full Text Available In this article, a combined general family of estimators is proposed for estimating finite population mean of a sensitive variable in stratified random sampling with non-sensitive auxiliary variable based on randomized response technique. Under stratified random sampling without replacement scheme, the expression of bias and mean square error (MSE up to the first-order approximations are derived. Theoretical and empirical results through a simulation study show that the proposed class of estimators is more efficient than the existing estimators, i.e., usual stratified random sample mean estimator, Sousa et al (2014 ratio and regression estimator of the sensitive variable in stratified sampling.

  1. High Levels of Sample-to-Sample Variation Confound Data Analysis for Non-Invasive Prenatal Screening of Fetal Microdeletions.

    Science.gov (United States)

    Chu, Tianjiao; Yeniterzi, Suveyda; Yatsenko, Svetlana A; Dunkel, Mary; Shaw, Patricia A; Bunce, Kimberly D; Peters, David G

    2016-01-01

    Our goal was to test the hypothesis that inter-individual genomic copy number variation in control samples is a confounding factor in the non-invasive prenatal detection of fetal microdeletions via the sequence-based analysis of maternal plasma DNA. The database of genomic variants (DGV) was used to determine the "Genomic Variants Frequency" (GVF) for each 50kb region in the human genome. Whole genome sequencing of fifteen karyotypically normal maternal plasma and six CVS DNA controls samples was performed. The coefficient of variation of relative read counts (cv.RTC) for these samples was determined for each 50kb region. Maternal plasma from two pregnancies affected with a chromosome 5p microdeletion was also sequenced, and analyzed using the GCREM algorithm. We found strong correlation between high variance in read counts and GVF amongst controls. Consequently we were unable to confirm the presence of the microdeletion via sequencing of maternal plasma samples obtained from two sequential affected pregnancies. Caution should be exercised when performing NIPT for microdeletions. It is vital to develop our understanding of the factors that impact the sensitivity and specificity of these approaches. In particular, benign copy number variation amongst controls is a major confounder, and their effects should be corrected bioinformatically.

  2. High Levels of Sample-to-Sample Variation Confound Data Analysis for Non-Invasive Prenatal Screening of Fetal Microdeletions.

    Directory of Open Access Journals (Sweden)

    Tianjiao Chu

    Full Text Available Our goal was to test the hypothesis that inter-individual genomic copy number variation in control samples is a confounding factor in the non-invasive prenatal detection of fetal microdeletions via the sequence-based analysis of maternal plasma DNA. The database of genomic variants (DGV was used to determine the "Genomic Variants Frequency" (GVF for each 50kb region in the human genome. Whole genome sequencing of fifteen karyotypically normal maternal plasma and six CVS DNA controls samples was performed. The coefficient of variation of relative read counts (cv.RTC for these samples was determined for each 50kb region. Maternal plasma from two pregnancies affected with a chromosome 5p microdeletion was also sequenced, and analyzed using the GCREM algorithm. We found strong correlation between high variance in read counts and GVF amongst controls. Consequently we were unable to confirm the presence of the microdeletion via sequencing of maternal plasma samples obtained from two sequential affected pregnancies. Caution should be exercised when performing NIPT for microdeletions. It is vital to develop our understanding of the factors that impact the sensitivity and specificity of these approaches. In particular, benign copy number variation amongst controls is a major confounder, and their effects should be corrected bioinformatically.

  3. Computer Corner: A Note on Pascal's Triangle and Simple Random Sampling.

    Science.gov (United States)

    Wright, Tommy

    1989-01-01

    Describes the algorithm used to select a simple random sample of certain size without having to list all possible samples and a justification based on Pascal's triangle. Provides testing results by various computers. (YP)

  4. Exponential ratio-product type estimators under second order approximation in stratified random sampling

    OpenAIRE

    Singh, Rajesh; Sharma, Prayas; Smarandache, Florentin

    2014-01-01

    Singh et al (20009) introduced a family of exponential ratio and product type estimators in stratified random sampling. Under stratified random sampling without replacement scheme, the expressions of bias and mean square error (MSE) of Singh et al (2009) and some other estimators, up to the first- and second-order approximations are derived. Also, the theoretical findings are supported by a numerical example.

  5. Query-Based Sampling: Can we do Better than Random?

    NARCIS (Netherlands)

    Tigelaar, A.S.; Hiemstra, Djoerd

    2010-01-01

    Many servers on the web offer content that is only accessible via a search interface. These are part of the deep web. Using conventional crawling to index the content of these remote servers is impossible without some form of cooperation. Query-based sampling provides an alternative to crawling

  6. Stratified random sampling plan for an irrigation customer telephone survey

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, J.W.; Davis, L.J.

    1986-05-01

    This report describes the procedures used to design and select a sample for a telephone survey of individuals who use electricity in irrigating agricultural cropland in the Pacific Northwest. The survey is intended to gather information on the irrigated agricultural sector that will be useful for conservation assessment, load forecasting, rate design, and other regional power planning activities.

  7. Weekday variation in triglyceride concentrations in 1.8 million blood samples

    DEFF Research Database (Denmark)

    Jaskolowski, Jörn; Ritz, Christian; Sjödin, Anders Mikael

    2017-01-01

    BACKGROUND: Triglyceride (TG) concentration is used as a marker of cardio-metabolic risk. However, diurnal and possibly weekday variation exists in TG concentrations. OBJECTIVE: To investigate weekday variation in TG concentrations among 1.8 million blood samples drawn between 2008 and 2015 from...... variations in TG concentrations were recorded for out-patients between the age of 9 to 26 years, with up to 20% higher values on Mondays compared to Fridays (all PTriglyceride concentrations were highest after the weekend and gradually declined during the week. We suggest that unhealthy...

  8. Fast egg collection method greatly improves randomness of egg sampling in Drosophila melanogaster

    DEFF Research Database (Denmark)

    Schou, Mads Fristrup

    2013-01-01

    When obtaining samples for population genetic studies, it is essential that the sampling is random. For Drosophila, one of the crucial steps in sampling experimental flies is the collection of eggs. Here an egg collection method is presented, which randomizes the eggs in a water column and dimini......When obtaining samples for population genetic studies, it is essential that the sampling is random. For Drosophila, one of the crucial steps in sampling experimental flies is the collection of eggs. Here an egg collection method is presented, which randomizes the eggs in a water column...... and to obtain a representative collection of genotypes, the method presented here is strongly recommended when collecting eggs from Drosophila....

  9. Children's stigmatization of childhood depression and ADHD: magnitude and demographic variation in a national sample.

    Science.gov (United States)

    Walker, Janet S; Coleman, Daniel; Lee, Junghee; Squire, Peter N; Friesen, Barbara J

    2008-08-01

    To estimate the magnitude of stigmatizing attitudes toward peers with depression or attention-deficit/hyperactivity disorder (ADHD) in a national sample of children ages 8 to 18 and to examine variation in level of stigma by school location, region of the United States, grade level, race/ethnicity, or sex. Surveys were administered to 1,318 children and adolescents. Respondents were randomly assigned to depression, ADHD, or asthma conditions and were presented with a vignette about a peer with one of the conditions. Participants responded to items assessing positive and negative attributions, social distance, and family attitudes. Mean differences were tested for statistical significance and effect sizes were computed. Respondents were more likely to make negative attributions about peers with ADHD and depression versus asthma, particularly regarding the likelihood of antisocial behavior and violence (Cohen d range 0.78-1.35, large effect sizes). Moderate effect sizes were found for preferences for social distance from peers with ADHD(d = 0.37) and depression (d = 0.45). Effects were found for perceptions of negative family attitudes toward both mental health conditions, with depression (d = 0.78) seen as even more stigmatized than ADHD (d = 0.47). The level of stigmatization was relatively constant across demographic variables, with the exception of greater stigmatization evident in Asian/Pacific Islander youths. Across most items, both depression and ADHD were more stigmatized than asthma, with depression more stigmatized than ADHD. The perception of likelihood of violence and antisocial behavior was particularly high for both ADHD and depression, greatly exceeding the real-world association for depression.

  10. Standardised Resting Time Prior to Blood Sampling and Diurnal Variation Associated with Risk of Patient Misclassification

    DEFF Research Database (Denmark)

    Bøgh Andersen, Ida; Brasen, Claus L.; Christensen, Henry

    2015-01-01

    BACKGROUND: According to current recommendations, blood samples should be taken in the morning after 15 minutes' resting time. Some components exhibit diurnal variation and in response to pressures to expand opening hours and reduce waiting time, the aims of this study were to investigate...... the impact of resting time prior to blood sampling and diurnal variation on biochemical components, including albumin, thyrotropin (TSH), total calcium and sodium in plasma. METHODS: All patients referred to an outpatient clinic for blood sampling were included in the period Nov 2011 until June 2014 (opening...... hours: 7am-3pm). Each patient's arrival time and time of blood sampling were registered. The impact of resting time and the time of day for all components was analysed using simple linear regression. The "maximum allowable bias" was used as quality indicator for the change in reference interval. RESULTS...

  11. Parameter Estimation in Stratified Cluster Sampling under Randomized Response Models for Sensitive Question Survey.

    Science.gov (United States)

    Pu, Xiangke; Gao, Ge; Fan, Yubo; Wang, Mian

    2016-01-01

    Randomized response is a research method to get accurate answers to sensitive questions in structured sample survey. Simple random sampling is widely used in surveys of sensitive questions but hard to apply on large targeted populations. On the other side, more sophisticated sampling regimes and corresponding formulas are seldom employed to sensitive question surveys. In this work, we developed a series of formulas for parameter estimation in cluster sampling and stratified cluster sampling under two kinds of randomized response models by using classic sampling theories and total probability formulas. The performances of the sampling methods and formulas in the survey of premarital sex and cheating on exams at Soochow University were also provided. The reliability of the survey methods and formulas for sensitive question survey was found to be high.

  12. Parameter Estimation in Stratified Cluster Sampling under Randomized Response Models for Sensitive Question Survey.

    Directory of Open Access Journals (Sweden)

    Xiangke Pu

    Full Text Available Randomized response is a research method to get accurate answers to sensitive questions in structured sample survey. Simple random sampling is widely used in surveys of sensitive questions but hard to apply on large targeted populations. On the other side, more sophisticated sampling regimes and corresponding formulas are seldom employed to sensitive question surveys. In this work, we developed a series of formulas for parameter estimation in cluster sampling and stratified cluster sampling under two kinds of randomized response models by using classic sampling theories and total probability formulas. The performances of the sampling methods and formulas in the survey of premarital sex and cheating on exams at Soochow University were also provided. The reliability of the survey methods and formulas for sensitive question survey was found to be high.

  13. A modern theory of random variation with applications in stochastic calculus, financial mathematics, and Feynman integration

    CERN Document Server

    Muldowney, Patrick

    2012-01-01

    A Modern Theory of Random Variation is a new and radical re-formulation of the mathematical underpinnings of subjects as diverse as investment, communication engineering, and quantum mechanics. Setting aside the classical theory of probability measure spaces, the book utilizes a mathematically rigorous version of the theory of random variation that bases itself exclusively on finitely additive probability distribution functions. In place of twentieth century Lebesgue integration and measure theory, the author uses the simpler concept of Riemann sums, and the non-absolute Riemann-type integration of Henstock. Readers are supplied with an accessible approach to standard elements of probability theory such as the central limmit theorem and Brownian motion as well as remarkable, new results on Feynman diagrams and stochastic integrals. Throughout the book, detailed numerical demonstrations accompany the discussions of abstract mathematical theory, from the simplest elements of the subject to the most complex. I...

  14. Changes in quality of life from a homelessness intervention: true change, response shift, or random variation.

    Science.gov (United States)

    Powell, Guido Antonio; Adair, Carol E; Streiner, David L; Mayo, Nancy; Latimer, Eric

    2017-07-01

    Participants experiencing homelessness and mental illness who received housing and support through the At Home/Chez Soi trial showed modest gains in quality of life (QOL) compared to treatment as usual participants. Participants' QOL ratings over time may have been affected by either response shift triggered by new life circumstances or by random variation in the meaning of QOL ratings. This study seeks to identify both phenomena to estimate the intervention's effect on true change in QOL. Using the residuals from a regression model of the global item of Lehman's 20-item quality of life interview (QOLI-20), latent trajectory analysis was used to identify response shift, while a measure of overall variability in residuals identified random variation of QOL. The latter was used to adjust group comparisons of QOLI-20 total scores and the global item. Equivalent distributions of both groups' participants across latent trajectory classes (χ 2  = 2.97, p = .397) suggest that the intervention did not trigger response shift. However, random variation interacted significantly with the treatment effect on global item ratings. For every increase of one standard deviation of residuals, treatment odds ratios decreased by a factor of 0.70 (SE 1.18, p = .036, 95% CI 0.50-0.98). Measuring random variation in QOL ratings from the standard deviation of residuals offers the ability to approximate, although indirectly, how participants' QOL is truly affected by a housing intervention. Specifically, we found that QOL improvement is more evident when QOL ratings have a consistent meaning over time.

  15. A Unified Approach to Power Calculation and Sample Size Determination for Random Regression Models

    Science.gov (United States)

    Shieh, Gwowen

    2007-01-01

    The underlying statistical models for multiple regression analysis are typically attributed to two types of modeling: fixed and random. The procedures for calculating power and sample size under the fixed regression models are well known. However, the literature on random regression models is limited and has been confined to the case of all…

  16. Temporal genetic variation as revealed by a microsatellite analysis of European sardine ( Sardina pilchardus) archived samples

    DEFF Research Database (Denmark)

    Ruggeri, Paolo; Splendiani, Andrea; Bonanomi, Sara

    2012-01-01

    ) that explain the genetic diversity variation, while the same parameters turned out to be more stable in the southern samples. In addition, we detected the presence of a genetic bottleneck and low effective population size ( Ne) values in several northern samples. Even if the northern and southern Adriatic...... of otoliths and scales from sampling locations of northern (Chioggia) and southern (Vieste) Adriatic Sea, with the aim to investigate the genetic effects of these stock biomass fluctuations. The northern samples showed significant reduction in observed heterozygosity ( HO) and mean number of alleles ( Na...... sardine samples belong to the same genetic stock, the more pronounced decrease in genetic variability recorded in the northern sample led us to speculate that a more intensive fishing pressure and a more pronounced oceanographic isolation of this area could have accentuated the effects of the genetic...

  17. A Family of Estimators of a Sensitive Variable Using Auxiliary Information in Stratified Random Sampling

    National Research Council Canada - National Science Library

    Nadia Mushtaq; Noor Ul Amin; Muhammad Hanif

    2017-01-01

    In this article, a combined general family of estimators is proposed for estimating finite population mean of a sensitive variable in stratified random sampling with non-sensitive auxiliary variable...

  18. A New Estimator For Population Mean Using Two Auxiliary Variables in Stratified random Sampling

    OpenAIRE

    Singh, Rajesh; Malik, Sachin

    2014-01-01

    In this paper, we suggest an estimator using two auxiliary variables in stratified random sampling. The propose estimator has an improvement over mean per unit estimator as well as some other considered estimators. Expressions for bias and MSE of the estimator are derived up to first degree of approximation. Moreover, these theoretical findings are supported by a numerical example with original data. Key words: Study variable, auxiliary variable, stratified random sampling, bias and mean squa...

  19. Conflict-cost based random sampling design for parallel MRI with low rank constraints

    Science.gov (United States)

    Kim, Wan; Zhou, Yihang; Lyu, Jingyuan; Ying, Leslie

    2015-05-01

    In compressed sensing MRI, it is very important to design sampling pattern for random sampling. For example, SAKE (simultaneous auto-calibrating and k-space estimation) is a parallel MRI reconstruction method using random undersampling. It formulates image reconstruction as a structured low-rank matrix completion problem. Variable density (VD) Poisson discs are typically adopted for 2D random sampling. The basic concept of Poisson disc generation is to guarantee samples are neither too close to nor too far away from each other. However, it is difficult to meet such a condition especially in the high density region. Therefore the sampling becomes inefficient. In this paper, we present an improved random sampling pattern for SAKE reconstruction. The pattern is generated based on a conflict cost with a probability model. The conflict cost measures how many dense samples already assigned are around a target location, while the probability model adopts the generalized Gaussian distribution which includes uniform and Gaussian-like distributions as special cases. Our method preferentially assigns a sample to a k-space location with the least conflict cost on the circle of the highest probability. To evaluate the effectiveness of the proposed random pattern, we compare the performance of SAKEs using both VD Poisson discs and the proposed pattern. Experimental results for brain data show that the proposed pattern yields lower normalized mean square error (NMSE) than VD Poisson discs.

  20. Misrepresenting random sampling? A systematic review of research papers in the Journal of Advanced Nursing.

    Science.gov (United States)

    Williamson, Graham R

    2003-11-01

    This paper discusses the theoretical limitations of the use of random sampling and probability theory in the production of a significance level (or P-value) in nursing research. Potential alternatives, in the form of randomization tests, are proposed. Research papers in nursing, medicine and psychology frequently misrepresent their statistical findings, as the P-values reported assume random sampling. In this systematic review of studies published between January 1995 and June 2002 in the Journal of Advanced Nursing, 89 (68%) studies broke this assumption because they used convenience samples or entire populations. As a result, some of the findings may be questionable. The key ideas of random sampling and probability theory for statistical testing (for generating a P-value) are outlined. The result of a systematic review of research papers published in the Journal of Advanced Nursing is then presented, showing how frequently random sampling appears to have been misrepresented. Useful alternative techniques that might overcome these limitations are then discussed. REVIEW LIMITATIONS: This review is limited in scope because it is applied to one journal, and so the findings cannot be generalized to other nursing journals or to nursing research in general. However, it is possible that other nursing journals are also publishing research articles based on the misrepresentation of random sampling. The review is also limited because in several of the articles the sampling method was not completely clearly stated, and in this circumstance a judgment has been made as to the sampling method employed, based on the indications given by author(s). Quantitative researchers in nursing should be very careful that the statistical techniques they use are appropriate for the design and sampling methods of their studies. If the techniques they employ are not appropriate, they run the risk of misinterpreting findings by using inappropriate, unrepresentative and biased samples.

  1. Variation of Peripheral Blood Mononuclear Cell RNA Quality in Archived Samples.

    Science.gov (United States)

    Kozlakidis, Zisis; Mant, Christine; Abdinur, Fartun; Cope, Andrew; Steiner, Szabi; Peakman, Mark; Hayday, Adrian; Cason, John

    2011-09-01

    The Infectious Diseases BioBank (IDB) has consistently archived peripheral blood mononuclear cell (PBMNC) RNA for transcriptome analyses. RNA is particularly labile, and hence, these samples provide a sensitive indicator for assessing the IDB's quality-assurance measures. Independent analyses of 104 PBMNC RNA specimens from 26 volunteers revealed that the mean RNA integrity number (RIN) was high (9.02), although RIN ranged between scores of 7 and 10. This variation of RIN values was not associated with ischemic time, PBMNC quality, number of samples processed per day, self-medication after immunization, freezer location, donor characteristics, differential white blood cell counts, or daily variation in RNA extractions (all P>0.05). RIN values were related to the date of collection, with those processed during mid-summer having highest RIN scores (P=0.0001). Amongst specimens with the lowest RIN scores, no common feature could be identified. Thus, no technical explanation for the variation in RNA quality could be ascertained and these may represent normal physiological variations. These data provide strong evidence that current IDB protocols for the isolation and preservation PBMNC RNA are robust.

  2. Bayesian and variational Bayesian approaches for flows in heterogeneous random media

    Science.gov (United States)

    Yang, Keren; Guha, Nilabja; Efendiev, Yalchin; Mallick, Bani K.

    2017-09-01

    In this paper, we study porous media flows in heterogeneous stochastic media. We propose an efficient forward simulation technique that is tailored for variational Bayesian inversion. As a starting point, the proposed forward simulation technique decomposes the solution into the sum of separable functions (with respect to randomness and the space), where each term is calculated based on a variational approach. This is similar to Proper Generalized Decomposition (PGD). Next, we apply a multiscale technique to solve for each term (as in [1]) and, further, decompose the random function into 1D fields. As a result, our proposed method provides an approximation hierarchy for the solution as we increase the number of terms in the expansion and, also, increase the spatial resolution of each term. We use the hierarchical solution distributions in a variational Bayesian approximation to perform uncertainty quantification in the inverse problem. We conduct a detailed numerical study to explore the performance of the proposed uncertainty quantification technique and show the theoretical posterior concentration.

  3. Contributions from the data samples in NOC technique on the extracting of the Sq variation

    Science.gov (United States)

    Wu, Yingyan; Xu, Wenyao

    2015-04-01

    The solar quiet daily variation, Sq, a rather regular variation is usually observed at mid-low latitudes on magnetic quiet days or less-disturbed days. It is mainly resulted from the dynamo currents in the ionospheric E region, which are driven by the atmospheric tidal wind and different processes and flow as two current whorls in each of the northern and southern hemispheres[1]. The Sq exhibits a conspicuous day-to-day (DTD) variability in daily range (or strength), shape (or phase) and its current focus. This variability is mainly attributed to changes in the ionospheric conductivity and tidal winds, varying with solar radiation and ionospheric conditions. Furthermore, it presents a seasonal variation and solar cycle variation[2-4]. In generally, Sq is expressed with the average value of the five international magnetic quiet days. Using data from global magnetic stations, equivalent current system of daily variation can be constructed to reveal characteristics of the currents[5]. In addition, using the differences of H component at two stations on north and south side of the Sq currents of focus, Sq is extracted much better[6]. Recently, the method of Natural Orthoganal Components (NOC) is used to decompose the magnetic daily variation and express it as the summation of eigenmodes, and indicate the first NOC eigenmode as the solar quiet daily variation, the second as the disturbance daily variation[7-9]. As we know, the NOC technique can help reveal simpler patterns within a complex set of variables, without designed basic-functions such as FFT technique. But the physical explanation of the NOC eigenmodes is greatly depends on the number of data samples and data regular-quality. Using the NOC method, we focus our present study on the analysis of the hourly means of the H component at BMT observatory in China from 2001 to 2008. The contributions of the number and the regular-quality of the data samples on which eigenmode corresponds to the Sq are analyzed, by

  4. Calculating sample sizes for cluster randomized trials: we can keep it simple and efficient !

    NARCIS (Netherlands)

    van Breukelen, Gerard J.P.; Candel, Math J.J.M.

    2012-01-01

    Objective: Simple guidelines for efficient sample sizes in cluster randomized trials with unknown intraclass correlation and varying cluster sizes. Methods: A simple equation is given for the optimal number of clusters and sample size per cluster. Here, optimal means maximizing power for a given

  5. Survey research with a random digit dial national mobile phone sample in Ghana: Methods and sample quality

    Science.gov (United States)

    Sefa, Eunice; Adimazoya, Edward Akolgo; Yartey, Emmanuel; Lenzi, Rachel; Tarpo, Cindy; Heward-Mills, Nii Lante; Lew, Katherine; Ampeh, Yvonne

    2018-01-01

    Introduction Generating a nationally representative sample in low and middle income countries typically requires resource-intensive household level sampling with door-to-door data collection. High mobile phone penetration rates in developing countries provide new opportunities for alternative sampling and data collection methods, but there is limited information about response rates and sample biases in coverage and nonresponse using these methods. We utilized data from an interactive voice response, random-digit dial, national mobile phone survey in Ghana to calculate standardized response rates and assess representativeness of the obtained sample. Materials and methods The survey methodology was piloted in two rounds of data collection. The final survey included 18 demographic, media exposure, and health behavior questions. Call outcomes and response rates were calculated according to the American Association of Public Opinion Research guidelines. Sample characteristics, productivity, and costs per interview were calculated. Representativeness was assessed by comparing data to the Ghana Demographic and Health Survey and the National Population and Housing Census. Results The survey was fielded during a 27-day period in February-March 2017. There were 9,469 completed interviews and 3,547 partial interviews. Response, cooperation, refusal, and contact rates were 31%, 81%, 7%, and 39% respectively. Twenty-three calls were dialed to produce an eligible contact: nonresponse was substantial due to the automated calling system and dialing of many unassigned or non-working numbers. Younger, urban, better educated, and male respondents were overrepresented in the sample. Conclusions The innovative mobile phone data collection methodology yielded a large sample in a relatively short period. Response rates were comparable to other surveys, although substantial coverage bias resulted from fewer women, rural, and older residents completing the mobile phone survey in

  6. Superresolution with compound Markov random fields via the variational EM algorithm.

    Science.gov (United States)

    Kanemura, Atsunori; Maeda, Shin-ichi; Ishii, Shin

    2009-09-01

    This study deals with a reconstruction-type superresolution problem and the accompanying image registration problem simultaneously. We propose a Bayesian approach in which the prior is modeled as a compound Gaussian Markov random field (MRF) and marginalization is performed over unknown variables to avoid overfitting. Our algorithm not only avoids overfitting, but also preserves discontinuity in the estimated image, unlike existing single-layer Gaussian MRF models for Bayesian superresolution. Maximum-marginal-likelihood estimation of the registration parameters is carried out using a variational EM algorithm where hidden variables are marginalized out, and the posterior distribution is variationally approximated by a factorized trial distribution. High-resolution image estimates are obtained through the process of posterior computation in the EM algorithm. Experiments show that our Bayesian approach with the two-layer compound model exhibits better performance both in quantitative measures and visual quality than the single-layer model.

  7. Novel Complete Probabilistic Models of Random Variation in High Frequency Performance of Nanoscale MOSFET

    Directory of Open Access Journals (Sweden)

    Rawid Banchuin

    2013-01-01

    Full Text Available The novel probabilistic models of the random variations in nanoscale MOSFET's high frequency performance defined in terms of gate capacitance and transition frequency have been proposed. As the transition frequency variation has also been considered, the proposed models are considered as complete unlike the previous one which take only the gate capacitance variation into account. The proposed models have been found to be both analytic and physical level oriented as they are the precise mathematical expressions in terms of physical parameters. Since the up-to-date model of variation in MOSFET's characteristic induced by physical level fluctuation has been used, part of the proposed models for gate capacitance is more accurate and physical level oriented than its predecessor. The proposed models have been verified based on the 65 nm CMOS technology by using the Monte-Carlo SPICE simulations of benchmark circuits and Kolmogorov-Smirnov tests as highly accurate since they fit the Monte-Carlo-based analysis results with 99% confidence. Hence, these novel models have been found to be versatile for the statistical/variability aware analysis/design of nanoscale MOSFET-based analog/mixed signal circuits and systems.

  8. Phenotypic variation in California populations of valley oak (Quercus lobata Née) sampled along elevational gradients

    Science.gov (United States)

    Ana L. Albarrán-Lara; Jessica W. Wright; Paul F. Gugger; Annette Delfino-Mix; Juan Manuel Peñaloza-Ramírez; Victoria L. Sork

    2015-01-01

    California oaks exhibit tremendous phenotypic variation throughout their range. This variation reflects phenotypic plasticity in tree response to local environmental conditions as well as genetic differences underlying those phenotypes. In this study, we analyze phenotypic variation in leaf traits for valley oak adults sampled along three elevational transects and in...

  9. Stratified random sampling for estimating billing accuracy in health care systems.

    Science.gov (United States)

    Buddhakulsomsiri, Jirachai; Parthanadee, Parthana

    2008-03-01

    This paper presents a stratified random sampling plan for estimating accuracy of bill processing performance for the health care bills submitted to third party payers in health care systems. Bill processing accuracy is estimated with two measures: percent accuracy and total dollar accuracy. Difficulties in constructing a sampling plan arise when the population strata structure is unknown, and when the two measures require different sampling schemes. To efficiently utilize sample resource, the sampling plan is designed to effectively estimate both measures from the same sample. The sampling plan features a simple but efficient strata construction method, called rectangular method, and two accuracy estimation methods, one for each measure. The sampling plan is tested on actual populations from an insurance company. Accuracy estimates obtained are then used to compare the rectangular method to other potential clustering methods for strata construction, and compare the accuracy estimation methods to other eligible methods. Computational study results show effectiveness of the proposed sampling plan.

  10. SNP selection and classification of genome-wide SNP data using stratified sampling random forests.

    Science.gov (United States)

    Wu, Qingyao; Ye, Yunming; Liu, Yang; Ng, Michael K

    2012-09-01

    For high dimensional genome-wide association (GWA) case-control data of complex disease, there are usually a large portion of single-nucleotide polymorphisms (SNPs) that are irrelevant with the disease. A simple random sampling method in random forest using default mtry parameter to choose feature subspace, will select too many subspaces without informative SNPs. Exhaustive searching an optimal mtry is often required in order to include useful and relevant SNPs and get rid of vast of non-informative SNPs. However, it is too time-consuming and not favorable in GWA for high-dimensional data. The main aim of this paper is to propose a stratified sampling method for feature subspace selection to generate decision trees in a random forest for GWA high-dimensional data. Our idea is to design an equal-width discretization scheme for informativeness to divide SNPs into multiple groups. In feature subspace selection, we randomly select the same number of SNPs from each group and combine them to form a subspace to generate a decision tree. The advantage of this stratified sampling procedure can make sure each subspace contains enough useful SNPs, but can avoid a very high computational cost of exhaustive search of an optimal mtry, and maintain the randomness of a random forest. We employ two genome-wide SNP data sets (Parkinson case-control data comprised of 408 803 SNPs and Alzheimer case-control data comprised of 380 157 SNPs) to demonstrate that the proposed stratified sampling method is effective, and it can generate better random forest with higher accuracy and lower error bound than those by Breiman's random forest generation method. For Parkinson data, we also show some interesting genes identified by the method, which may be associated with neurological disorders for further biological investigations.

  11. Mendelian breeding units versus standard sampling strategies: mitochondrial DNA variation in southwest Sardinia

    Directory of Open Access Journals (Sweden)

    Daria Sanna

    2011-01-01

    Full Text Available We report a sampling strategy based on Mendelian Breeding Units (MBUs, representing an interbreeding group of individuals sharing a common gene pool. The identification of MBUs is crucial for case-control experimental design in association studies. The aim of this work was to evaluate the possible existence of bias in terms of genetic variability and haplogroup frequencies in the MBU sample, due to severe sample selection. In order to reach this goal, the MBU sampling strategy was compared to a standard selection of individuals according to their surname and place of birth. We analysed mitochondrial DNA variation (first hypervariable segment and coding region in unrelated healthy subjects from two different areas of Sardinia: the area around the town of Cabras and the western Campidano area. No statistically significant differences were observed when the two sampling methods were compared, indicating that the stringent sample selection needed to establish a MBU does not alter original genetic variability and haplogroup distribution. Therefore, the MBU sampling strategy can be considered a useful tool in association studies of complex traits.

  12. Random Walks on Directed Networks: Inference and Respondent-driven Sampling

    CERN Document Server

    Malmros, Jens; Britton, Tom

    2013-01-01

    Respondent driven sampling (RDS) is a method often used to estimate population properties (e.g. sexual risk behavior) in hard-to-reach populations. It combines an effective modified snowball sampling methodology with an estimation procedure that yields unbiased population estimates under the assumption that the sampling process behaves like a random walk on the social network of the population. Current RDS estimation methodology assumes that the social network is undirected, i.e. that all edges are reciprocal. However, empirical social networks in general also have non-reciprocated edges. To account for this fact, we develop a new estimation method for RDS in the presence of directed edges on the basis of random walks on directed networks. We distinguish directed and undirected edges and consider the possibility that the random walk returns to its current position in two steps through an undirected edge. We derive estimators of the selection probabilities of individuals as a function of the number of outgoing...

  13. Intrapopulational body size variation and cranial capacity variation in Middle Pleistocene humans: the Sima de los Huesos sample (Sierra de Atapuerca, Spain).

    Science.gov (United States)

    Lorenzo, C; Carretero, J M; Arsuaga, J L; Gracia, A; Martínez, I

    1998-05-01

    A sexual dimorphism more marked than in living humans has been claimed for European Middle Pleistocene humans, Neandertals and prehistoric modern humans. In this paper, body size and cranial capacity variation are studied in the Sima de los Huesos Middle Pleistocene sample. This is the largest sample of non-modern humans found to date from one single site, and with all skeletal elements represented. Since the techniques available to estimate the degree of sexual dimorphism in small palaeontological samples are all unsatisfactory, we have used the bootstraping method to asses the magnitude of the variation in the Sima de los Huesos sample compared to modern human intrapopulational variation. We analyze size variation without attempting to sex the specimens a priori. Anatomical regions investigated are scapular glenoid fossa; acetabulum; humeral proximal and distal epiphyses; ulnar proximal epiphysis; radial neck; proximal femur; humeral, femoral, ulnar and tibial shaft; lumbosacral joint; patella; calcaneum; and talar trochlea. In the Sima de los Huesos sample only the humeral midshaft perimeter shows an unusual high variation (only when it is expressed by the maximum ratio, not by the coefficient of variation). In spite of that the cranial capacity range at Sima de los Huesos almost spans the rest of the European and African Middle Pleistocene range. The maximum ratio is in the central part of the distribution of modern human samples. Thus, the hypothesis of a greater sexual dimorphism in Middle Pleistocene populations than in modern populations is not supported by either cranial or postcranial evidence from Sima de los Huesos.

  14. Multidrug resistance among new tuberculosis cases: detecting local variation through lot quality-assurance sampling.

    Science.gov (United States)

    Hedt, Bethany Lynn; van Leth, Frank; Zignol, Matteo; Cobelens, Frank; van Gemert, Wayne; Nhung, Nguyen Viet; Lyepshina, Svitlana; Egwaga, Saidi; Cohen, Ted

    2012-03-01

    Current methodology for multidrug-resistant tuberculosis (MDR TB) surveys endorsed by the World Health Organization provides estimates of MDR TB prevalence among new cases at the national level. On the aggregate, local variation in the burden of MDR TB may be masked. This paper investigates the utility of applying lot quality-assurance sampling to identify geographic heterogeneity in the proportion of new cases with multidrug resistance. We simulated the performance of lot quality-assurance sampling by applying these classification-based approaches to data collected in the most recent TB drug-resistance surveys in Ukraine, Vietnam, and Tanzania. We explored 3 classification systems- two-way static, three-way static, and three-way truncated sequential sampling-at 2 sets of thresholds: low MDR TB = 2%, high MDR TB = 10%, and low MDR TB = 5%, high MDR TB = 20%. The lot quality-assurance sampling systems identified local variability in the prevalence of multidrug resistance in both high-resistance (Ukraine) and low-resistance settings (Vietnam). In Tanzania, prevalence was uniformly low, and the lot quality-assurance sampling approach did not reveal variability. The three-way classification systems provide additional information, but sample sizes may not be obtainable in some settings. New rapid drug-sensitivity testing methods may allow truncated sequential sampling designs and early stopping within static designs, producing even greater efficiency gains. Lot quality-assurance sampling study designs may offer an efficient approach for collecting critical information on local variability in the burden of multidrug-resistant TB. Before this methodology is adopted, programs must determine appropriate classification thresholds, the most useful classification system, and appropriate weighting if unbiased national estimates are also desired.

  15. Calibration of Passive Samplers for the Monitoring of Pharmaceuticals in Water-Sampling Rate Variation.

    Science.gov (United States)

    Męczykowska, Hanna; Kobylis, Paulina; Stepnowski, Piotr; Caban, Magda

    2017-05-04

    Passive sampling is one of the most efficient methods of monitoring pharmaceuticals in environmental water. The reliability of the process relies on a correctly performed calibration experiment and a well-defined sampling rate (Rs) for target analytes. Therefore, in this review the state-of-the-art methods of passive sampler calibration for the most popular pharmaceuticals: antibiotics, hormones, β-blockers and non-steroidal anti-inflammatory drugs (NSAIDs), along with the sampling rate variation, were presented. The advantages and difficulties in laboratory and field calibration were pointed out, according to the needs of control of the exact conditions. Sampling rate calculating equations and all the factors affecting the Rs value - temperature, flow, pH, salinity of the donor phase and biofouling - were discussed. Moreover, various calibration parameters gathered from the literature published in the last 16 years, including the device types, were tabled and compared. What is evident is that the sampling rate values for pharmaceuticals are impacted by several factors, whose influence is still unclear and unpredictable, while there is a big gap in experimental data. It appears that the calibration procedure needs to be improved, for example, there is a significant deficiency of PRCs (Performance Reference Compounds) for pharmaceuticals. One of the suggestions is to introduce correction factors for Rs values estimated in laboratory conditions.

  16. Seasonal Variation, Chemical Composition and Antioxidant Activity of Brazilian Propolis Samples

    Directory of Open Access Journals (Sweden)

    Érica Weinstein Teixeira

    2010-01-01

    Full Text Available Total phenolic contents, antioxidant activity and chemical composition of propolis samples from three localities of Minas Gerais state (southeast Brazil were determined. Total phenolic contents were determined by the Folin–Ciocalteau method, antioxidant activity was evaluated by DPPH, using BHT as reference, and chemical composition was analyzed by GC/MS. Propolis from Itapecerica and Paula Cândido municipalities were found to have high phenolic contents and pronounced antioxidant activity. From these extracts, 40 substances were identified, among them were simple phenylpropanoids, prenylated phenylpropanoids, sesqui- and diterpenoids. Quantitatively, the main constituent of both samples was allyl-3-prenylcinnamic acid. A sample from Virginópolis municipality had no detectable phenolic substances and contained mainly triterpenoids, the main constituents being α- and β-amyrins. Methanolic extracts from Itapecerica and Paula Cândido exhibited pronounced scavenging activity towards DPPH, indistinguishable from BHT activity. However, extracts from Virginópolis sample exhibited no antioxidant activity. Total phenolic substances, GC/MS analyses and antioxidant activity of samples from Itapecerica collected monthly over a period of 1 year revealed considerable variation. No correlation was observed between antioxidant activity and either total phenolic contents or contents of artepillin C and other phenolic substances, as assayed by CG/MS analysis.

  17. Spatial Variation of Soil Lead in an Urban Community Garden: Implications for Risk-Based Sampling.

    Science.gov (United States)

    Bugdalski, Lauren; Lemke, Lawrence D; McElmurry, Shawn P

    2014-01-01

    Soil lead pollution is a recalcitrant problem in urban areas resulting from a combination of historical residential, industrial, and transportation practices. The emergence of urban gardening movements in postindustrial cities necessitates accurate assessment of soil lead levels to ensure safe gardening. In this study, we examined small-scale spatial variability of soil lead within a 15 × 30 m urban garden plot established on two adjacent residential lots located in Detroit, Michigan, USA. Eighty samples collected using a variably spaced sampling grid were analyzed for total, fine fraction (less than 250 μm), and bioaccessible soil lead. Measured concentrations varied at sampling scales of 1-10 m and a hot spot exceeding 400 ppm total soil lead was identified in the northwest portion of the site. An interpolated map of total lead was treated as an exhaustive data set, and random sampling was simulated to generate Monte Carlo distributions and evaluate alternative sampling strategies intended to estimate the average soil lead concentration or detect hot spots. Increasing the number of individual samples decreases the probability of overlooking the hot spot (type II error). However, the practice of compositing and averaging samples decreased the probability of overestimating the mean concentration (type I error) at the expense of increasing the chance for type II error. The results reported here suggest a need to reconsider U.S. Environmental Protection Agency sampling objectives and consequent guidelines for reclaimed city lots where soil lead distributions are expected to be nonuniform. © 2013 Society for Risk Analysis.

  18. Estimation of Sensitive Proportion by Randomized Response Data in Successive Sampling

    Directory of Open Access Journals (Sweden)

    Bo Yu

    2015-01-01

    Full Text Available This paper considers the problem of estimation for binomial proportions of sensitive or stigmatizing attributes in the population of interest. Randomized response techniques are suggested for protecting the privacy of respondents and reducing the response bias while eliciting information on sensitive attributes. In many sensitive question surveys, the same population is often sampled repeatedly on each occasion. In this paper, we apply successive sampling scheme to improve the estimation of the sensitive proportion on current occasion.

  19. Random sampling of elementary flux modes in large-scale metabolic networks.

    Science.gov (United States)

    Machado, Daniel; Soons, Zita; Patil, Kiran Raosaheb; Ferreira, Eugénio C; Rocha, Isabel

    2012-09-15

    The description of a metabolic network in terms of elementary (flux) modes (EMs) provides an important framework for metabolic pathway analysis. However, their application to large networks has been hampered by the combinatorial explosion in the number of modes. In this work, we develop a method for generating random samples of EMs without computing the whole set. Our algorithm is an adaptation of the canonical basis approach, where we add an additional filtering step which, at each iteration, selects a random subset of the new combinations of modes. In order to obtain an unbiased sample, all candidates are assigned the same probability of getting selected. This approach avoids the exponential growth of the number of modes during computation, thus generating a random sample of the complete set of EMs within reasonable time. We generated samples of different sizes for a metabolic network of Escherichia coli, and observed that they preserve several properties of the full EM set. It is also shown that EM sampling can be used for rational strain design. A well distributed sample, that is representative of the complete set of EMs, should be suitable to most EM-based methods for analysis and optimization of metabolic networks. Source code for a cross-platform implementation in Python is freely available at http://code.google.com/p/emsampler. dmachado@deb.uminho.pt Supplementary data are available at Bioinformatics online.

  20. Power and sample size calculations for Mendelian randomization studies using one genetic instrument.

    Science.gov (United States)

    Freeman, Guy; Cowling, Benjamin J; Schooling, C Mary

    2013-08-01

    Mendelian randomization, which is instrumental variable analysis using genetic variants as instruments, is an increasingly popular method of making causal inferences from observational studies. In order to design efficient Mendelian randomization studies, it is essential to calculate the sample sizes required. We present formulas for calculating the power of a Mendelian randomization study using one genetic instrument to detect an effect of a given size, and the minimum sample size required to detect effects for given levels of significance and power, using asymptotic statistical theory. We apply the formulas to some example data and compare the results with those from simulation methods. Power and sample size calculations using these formulas should be more straightforward to carry out than simulation approaches. These formulas make explicit that the sample size needed for Mendelian randomization study is inversely proportional to the square of the correlation between the genetic instrument and the exposure and proportional to the residual variance of the outcome after removing the effect of the exposure, as well as inversely proportional to the square of the effect size.

  1. Sampling versus Random Binning for Multiple Descriptions of a Bandlimited Source

    DEFF Research Database (Denmark)

    Mashiach, Adam; Østergaard, Jan; Zamir, Ram

    2013-01-01

    Random binning is an efficient, yet complex, coding technique for the symmetric L-description source coding problem. We propose an alternative approach, that uses the quantized samples of a bandlimited source as "descriptions". By the Nyquist condition, the source can be reconstructed if enough s...

  2. Recidivism among Child Sexual Abusers: Initial Results of a 13-Year Longitudinal Random Sample

    Science.gov (United States)

    Patrick, Steven; Marsh, Robert

    2009-01-01

    In the initial analysis of data from a random sample of all those charged with child sexual abuse in Idaho over a 13-year period, only one predictive variable was found that related to recidivism of those convicted. Variables such as ethnicity, relationship, gender, and age differences did not show a significant or even large association with…

  3. HABITAT ASSESSMENT USING A RANDOM PROBABILITY BASED SAMPLING DESIGN: ESCAMBIA RIVER DELTA, FLORIDA

    Science.gov (United States)

    Smith, Lisa M., Darrin D. Dantin and Steve Jordan. In press. Habitat Assessment Using a Random Probability Based Sampling Design: Escambia River Delta, Florida (Abstract). To be presented at the SWS/GERS Fall Joint Society Meeting: Communication and Collaboration: Coastal Systems...

  4. Reinforcing Sampling Distributions through a Randomization-Based Activity for Introducing ANOVA

    Science.gov (United States)

    Taylor, Laura; Doehler, Kirsten

    2015-01-01

    This paper examines the use of a randomization-based activity to introduce the ANOVA F-test to students. The two main goals of this activity are to successfully teach students to comprehend ANOVA F-tests and to increase student comprehension of sampling distributions. Four sections of students in an advanced introductory statistics course…

  5. Flexible sampling large-scale social networks by self-adjustable random walk

    Science.gov (United States)

    Xu, Xiao-Ke; Zhu, Jonathan J. H.

    2016-12-01

    Online social networks (OSNs) have become an increasingly attractive gold mine for academic and commercial researchers. However, research on OSNs faces a number of difficult challenges. One bottleneck lies in the massive quantity and often unavailability of OSN population data. Sampling perhaps becomes the only feasible solution to the problems. How to draw samples that can represent the underlying OSNs has remained a formidable task because of a number of conceptual and methodological reasons. Especially, most of the empirically-driven studies on network sampling are confined to simulated data or sub-graph data, which are fundamentally different from real and complete-graph OSNs. In the current study, we propose a flexible sampling method, called Self-Adjustable Random Walk (SARW), and test it against with the population data of a real large-scale OSN. We evaluate the strengths of the sampling method in comparison with four prevailing methods, including uniform, breadth-first search (BFS), random walk (RW), and revised RW (i.e., MHRW) sampling. We try to mix both induced-edge and external-edge information of sampled nodes together in the same sampling process. Our results show that the SARW sampling method has been able to generate unbiased samples of OSNs with maximal precision and minimal cost. The study is helpful for the practice of OSN research by providing a highly needed sampling tools, for the methodological development of large-scale network sampling by comparative evaluations of existing sampling methods, and for the theoretical understanding of human networks by highlighting discrepancies and contradictions between existing knowledge/assumptions of large-scale real OSN data.

  6. Variations in reporting of outcomes in randomized trials on diet and physical activity in pregnancy

    DEFF Research Database (Denmark)

    Rogozińska, Ewelina; Marlin, Nadine; Yang, Fen

    2017-01-01

    AIM: Trials on diet and physical activity in pregnancy report on various outcomes. We aimed to assess the variations in outcomes reported and their quality in trials on lifestyle interventions in pregnancy. METHODS: We searched major databases without language restrictions for randomized controlled...... trials on diet and physical activity-based interventions in pregnancy up to March 2015. Two independent reviewers undertook study selection and data extraction. We estimated the percentage of papers reporting 'critically important' and 'important' outcomes. We defined the quality of reporting.......6%, 40/66), were the commonly reported 'critically important' outcomes. Gestational weight gain (84.5%, 56/66) and birth weight (87.9%, 58/66) were reported in most papers, although not considered critically important. The median quality of reporting was 0.60 (interquartile range 0.25, 0...

  7. Correlation between static random access memory power-up state and transistor variation

    Science.gov (United States)

    Takeuchi, Kiyoshi; Mizutani, Tomoko; Saraya, Takuya; Shinohara, Hirofumi; Kobayashi, Masaharu; Hiramoto, Toshiro

    2017-04-01

    The correlation between the static random access memory (SRAM) power-up state (i.e., state 0 or 1 immediately after the power supply is turned on) and cell transistor variation is systematically studied by circuit simulations and mismatch space partitioning. It is revealed that, while both the mismatches of pFETs (pull-up) and nFETs (pull-down and access) contribute, their relative importance changes depending on the voltage ramping speed. The static retention noise margin well correlates with the power-up state only if the ramping speed is sufficiently low. Otherwise, pull-up transistor mismatch dominates the power-up state determination owing to the interference of capacitive current and asymmetrical capacitive coupling of the storage nodes to the ground and power supply.

  8. Random amplified polymorphic DNA analysis and variation of essential oil components of Atractylodes plants.

    Science.gov (United States)

    Kohjyouma, M; Nakajima, S; Namera, A; Shimizu, R; Mizukami, H; Kohda, H

    1997-05-01

    Total DNAs were prepared from the leaves of Atractylodes lancea DE CANDOLLE, A. chinensis KOIDZUMI, A. lancea var. simplicifolia KITAMURA, A. japonica KOIDZUMI ex KITAMURA and A. ovata DE CANDOLLE. The DNAs were subjected to random amplified polymorphic DNA (RAPD) analysis. Some primers showed the definitive polymorphic DNA patterns in A. lancea, A. japonica and A. ovata. The RAPD of A. lancea var. simplicifolia and one of A. chinensis gave similar patterns to those of A. lancea, but one of the other A. chinensis gave a similar pattern to A. japonica. Furthermore, quantitative analysis of atractylon, hinesol, beta-eudesmol and atractylodin in the rhizomes was done using gas chromatography. Though atractylon was detected not only in A. japonica and A. ovata but also in some of A. lancea, their RAPD profiles revealed the presence of intraspecific variation with A. lancea.

  9. The variation in surface morphology and hardness of human deciduous teeth samples after laser irradiation

    Science.gov (United States)

    Khalid, Arooj; Bashir, Shazia; Akram, Mahreen; Salman Ahmed, Qazi

    2017-11-01

    The variation in surface morphology and hardness of human deciduous teeth samples has been investigated after laser irradiation at different wavelengths and energies. Nd:YAG was employed as a source of irradiation for IR (1064 nm) and visible (532 nm) radiation, whereas an excimer laser was used as the source of UV (248 nm) radiation. Scanning electron microscope (SEM) analysis was carried out to reveal the surface morphological evolution of teeth samples. Vickers microhardness tester was employed to investigate the modifications in the hardness of the laser-treated samples. It is observed from SEM analysis that IR wavelength is responsible for ablation of collagen matrix and intertubular dentine. For visible radiation, the ablation of collagen along with hydroxypatite is observed. With UV radiation, the ablation of peritubular dentine is dominant and is responsible for the sealing of tubules. The decrease in hardness at lower energy for both wavelengths is due to the evaporation of carbon content. With increasing energy, evaporation of water along with carbon content, and resolidification and re-organization of inorganic content causes the increase in hardness of the treated dentine. SEM as well as microhardness analyses reveal that laser wavelengths and energy of laser radiation significantly influence the surface morphology and hardness of samples.

  10. The quality of the reported sample size calculations in randomized controlled trials indexed in PubMed.

    Science.gov (United States)

    Lee, Paul H; Tse, Andy C Y

    2017-05-01

    There are limited data on the quality of reporting of information essential for replication of the calculation as well as the accuracy of the sample size calculation. We examine the current quality of reporting of the sample size calculation in randomized controlled trials (RCTs) published in PubMed and to examine the variation in reporting across study design, study characteristics, and journal impact factor. We also reviewed the targeted sample size reported in trial registries. We reviewed and analyzed all RCTs published in December 2014 with journals indexed in PubMed. The 2014 Impact Factors for the journals were used as proxies for their quality. Of the 451 analyzed papers, 58.1% reported an a priori sample size calculation. Nearly all papers provided the level of significance (97.7%) and desired power (96.6%), and most of the papers reported the minimum clinically important effect size (73.3%). The median (inter-quartile range) of the percentage difference of the reported and calculated sample size calculation was 0.0% (IQR -4.6%;3.0%). The accuracy of the reported sample size was better for studies published in journals that endorsed the CONSORT statement and journals with an impact factor. A total of 98 papers had provided targeted sample size on trial registries and about two-third of these papers (n=62) reported sample size calculation, but only 25 (40.3%) had no discrepancy with the reported number in the trial registries. The reporting of the sample size calculation in RCTs published in PubMed-indexed journals and trial registries were poor. The CONSORT statement should be more widely endorsed. Copyright © 2016 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  11. Sample size calculations for micro-randomized trials in mHealth.

    Science.gov (United States)

    Liao, Peng; Klasnja, Predrag; Tewari, Ambuj; Murphy, Susan A

    2016-05-30

    The use and development of mobile interventions are experiencing rapid growth. In "just-in-time" mobile interventions, treatments are provided via a mobile device, and they are intended to help an individual make healthy decisions 'in the moment,' and thus have a proximal, near future impact. Currently, the development of mobile interventions is proceeding at a much faster pace than that of associated data science methods. A first step toward developing data-based methods is to provide an experimental design for testing the proximal effects of these just-in-time treatments. In this paper, we propose a 'micro-randomized' trial design for this purpose. In a micro-randomized trial, treatments are sequentially randomized throughout the conduct of the study, with the result that each participant may be randomized at the 100s or 1000s of occasions at which a treatment might be provided. Further, we develop a test statistic for assessing the proximal effect of a treatment as well as an associated sample size calculator. We conduct simulation evaluations of the sample size calculator in various settings. Rules of thumb that might be used in designing a micro-randomized trial are discussed. This work is motivated by our collaboration on the HeartSteps mobile application designed to increase physical activity. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  12. Occupational position and its relation to mental distress in a random sample of Danish residents

    DEFF Research Database (Denmark)

    Rugulies, Reiner Ernst; Madsen, Ida E H; Nielsen, Maj Britt D

    2010-01-01

    somatization symptoms (OR = 6.28, 95% CI = 1.39-28.46). CONCLUSIONS: Unskilled manual workers, the unemployed, and, to a lesser extent, the low-grade self-employed showed an increased level of mental distress. Activities to promote mental health in the Danish population should be directed toward these groups.......PURPOSE: To analyze the distribution of depressive, anxiety, and somatization symptoms across different occupational positions in a random sample of Danish residents. METHODS: The study sample consisted of 591 Danish residents (50% women), aged 20-65, drawn from an age- and gender-stratified random...... sample of the Danish population. Participants filled out a survey that included the 92 item version of the Hopkins Symptom Checklist (SCL-92). We categorized occupational position into seven groups: high- and low-grade non-manual workers, skilled and unskilled manual workers, high- and low-grade self...

  13. Random sampling for a mental health survey in a deprived multi-ethnic area of Berlin.

    Science.gov (United States)

    Mundt, Adrian P; Aichberger, Marion C; Kliewe, Thomas; Ignatyev, Yuriy; Yayla, Seda; Heimann, Hannah; Schouler-Ocak, Meryam; Busch, Markus; Rapp, Michael; Heinz, Andreas; Ströhle, Andreas

    2012-12-01

    The aim of the study was to assess the response to random sampling for a mental health survey in a deprived multi-ethnic area of Berlin, Germany, with a large Turkish-speaking population. A random list from the registration office with 1,000 persons stratified by age and gender was retrieved from the population registry and these persons were contacted using a three-stage design including written information, telephone calls and personal contact at home. A female bilingual interviewer contacted persons with Turkish names. Of the persons on the list, 202 were not living in the area, one was deceased, 502 did not respond. Of the 295 responders, 152 explicitly refused(51.5%) to participate. We retained a sample of 143 participants(48.5%) representing the rate of multi-ethnicity in the area (52.1% migrants in the sample vs. 53.5% in the population). Turkish migrants were over-represented(28.9% in the sample vs. 18.6% in the population). Polish migrants (2.1 vs. 5.3% in the population) and persons from the former Yugoslavia (1.4 vs. 4.8% in the population)were under-represented. Bilingual contact procedures can improve the response rates of the most common migrant populations to random sampling if migrants of the same origin gate the contact. High non-contact and non-response rates for migrant and non-migrant populations in deprived urban areas remain a challenge for obtaining representative random samples.

  14. Assessment of proteinuria by using protein: creatinine index in random urine sample.

    Science.gov (United States)

    Khan, Dilshad Ahmed; Ahmad, Tariq Mahmood; Qureshil, Ayaz Hussain; Halim, Abdul; Ahmad, Mumtaz; Afzal, Saeed

    2005-10-01

    To assess the quantitative measurement of proteinuria by using random urine protein:creatinine index/ratio in comparison with 24 hours urinary protein excretion in patients of renal diseases having normal glomerular filtration rate. One hundred and thirty patients, 94 males and 36 females, with an age range of 5 to 60 years; having proteinuria of more than 150 mg/day were included in this study. Qualitative urinary protein estimation was done on random urine specimen by dipstick. Quantitative measurement of protein in the random and 24 hours urine specimens were carried out by a method based on the formation of a red complex of protein with pyrogallal red in acid medium on Micro lab 200 (Merck). Estimation of creatinine was done on Selectra -2 (Merck) by Jaffe's reaction. The urine protein:creatinine index and ratio were calculated by dividing the urine protein concentration (mg/L) by urine creatinine concentration (mmol/L) multilplied by 10 and mg/mg respectively. The protein:creatinine index and ratio of more than 140 and 0.18 respectively in a random urine sample indicated pathological proteinuria. An excellent correlation (r=0.96) was found between random urine protein:creatinine index/ratio and standard 24 hours urinary protein excretion in these patients (pprotein:creatinine index in random urine is a convenient, quick and reliable method of estimation of proteinuria as compared to 24 hours of urinary protein excretion for diagnosis and monitoring of renal diseases in our medical setup.

  15. Quasi optimal and adaptive sparse grids with control variates for PDEs with random diffusion coefficient

    KAUST Repository

    Tamellini, Lorenzo

    2016-01-05

    In this talk we discuss possible strategies to minimize the impact of the curse of dimensionality effect when building sparse-grid approximations of a multivariate function u = u(y1, ..., yN ). More precisely, we present a knapsack approach , in which we estimate the cost and the error reduction contribution of each possible component of the sparse grid, and then we choose the components with the highest error reduction /cost ratio. The estimates of the error reduction are obtained by either a mixed a-priori / a-posteriori approach, in which we first derive a theoretical bound and then tune it with some inexpensive auxiliary computations (resulting in the so-called quasi-optimal sparse grids ), or by a fully a-posteriori approach (obtaining the so-called adaptive sparse grids ). This framework is very general and can be used to build quasi-optimal/adaptive sparse grids on bounded and unbounded domains (e.g. u depending on uniform and normal random distributions for yn), using both nested and non-nested families of univariate collocation points. We present some theoretical convergence results as well as numerical results showing the efficiency of the proposed approach for the approximation of the solution of elliptic PDEs with random diffusion coefficients. In this context, to treat the case of rough permeability fields in which a sparse grid approach may not be suitable, we propose to use the sparse grids as a control variate in a Monte Carlo simulation.

  16. Generalized essential energy space random walks to more effectively accelerate solute sampling in aqueous environment.

    Science.gov (United States)

    Lv, Chao; Zheng, Lianqing; Yang, Wei

    2012-01-28

    Molecular dynamics sampling can be enhanced via the promoting of potential energy fluctuations, for instance, based on a Hamiltonian modified with the addition of a potential-energy-dependent biasing term. To overcome the diffusion sampling issue, which reveals the fact that enlargement of event-irrelevant energy fluctuations may abolish sampling efficiency, the essential energy space random walk (EESRW) approach was proposed earlier. To more effectively accelerate the sampling of solute conformations in aqueous environment, in the current work, we generalized the EESRW method to a two-dimension-EESRW (2D-EESRW) strategy. Specifically, the essential internal energy component of a focused region and the essential interaction energy component between the focused region and the environmental region are employed to define the two-dimensional essential energy space. This proposal is motivated by the general observation that in different conformational events, the two essential energy components have distinctive interplays. Model studies on the alanine dipeptide and the aspartate-arginine peptide demonstrate sampling improvement over the original one-dimension-EESRW strategy; with the same biasing level, the present generalization allows more effective acceleration of the sampling of conformational transitions in aqueous solution. The 2D-EESRW generalization is readily extended to higher dimension schemes and employed in more advanced enhanced-sampling schemes, such as the recent orthogonal space random walk method. © 2012 American Institute of Physics

  17. Multilayer pixel super-resolution lensless in-line holographic microscope with random sample movement.

    Science.gov (United States)

    Wang, Mingjun; Feng, Shaodong; Wu, Jigang

    2017-10-06

    We report a multilayer lensless in-line holographic microscope (LIHM) with improved imaging resolution by using the pixel super-resolution technique and random sample movement. In our imaging system, a laser beam illuminated the sample and a CMOS imaging sensor located behind the sample recorded the in-line hologram for image reconstruction. During the imaging process, the sample was moved by hand randomly and the in-line holograms were acquired sequentially. Then the sample image was reconstructed from an enhanced-resolution hologram obtained from multiple low-resolution in-line holograms by applying the pixel super-resolution (PSR) technique. We studied the resolution enhancement effects by using the U.S. Air Force (USAF) target as the sample in numerical simulation and experiment. We also showed that multilayer pixel super-resolution images can be obtained by imaging a triple-layer sample made with the filamentous algae on the middle layer and microspheres with diameter of 2 μm on the top and bottom layers. Our pixel super-resolution LIHM provides a compact and low-cost solution for microscopic imaging and is promising for many biomedical applications.

  18. Anatomical Variations May Interfere with Bilateral Inferior Petrosal Sinus Sampling Results -Case Report

    Directory of Open Access Journals (Sweden)

    Kürşad

    2010-12-01

    Full Text Available The diagnosis of Cushing’s syndrome (CS is still one of the most challenging problems in endocrinology. In ACTH-dependent CS, bilateral inferior petrosal sinus sampling (BIPSS is a useful method for distinguishing between pituitary and ectopic sources of ACTH secretion. BIPSS is an interventional radiology method, in which ACTH levels obtained from petrosal sinuses are compared to peripheral venous blood ACTH levels at basal conditions and after corticotropin-releasing hormone (CRH or desmopressin (DDAVP stimulation. A gradient between central and peripheral sources of ACTH indicates Cushing’s disease (CD, whereas the absence of a gradient suggests ectopic CS. In some cases, intrapituitary gradients from side-to-side may also help to predict the side of the adenoma within the pituitary. However, anatomical variations may lead to false lateralization of the lesion in the pituitary gland during BIPSS. We report the case of a 51-year-old woman with CD in whom BIPSS indicated a central source of secretion of ACTH, but it was not compatible with the side of the adenoma on MRI. The laboratory results after BIPSS were inconsistent with the radiological findings of the patient. The hypoplastic right petrosal sinus, which was discovered during angiography, was the cause of the abnormality. To avoid false interpretation of BIPSS results due to such anatomical variations, angiographic imaging is a commonly used technique before this procedure. As in our case, if laboratory results after BIPSS are not compatible with the earlier radiological findings, possible anatomical variations seen in angiography procedure before BIPSS should be taken into consideration. Turk Jem 2010; 14: 95-9

  19. Hardness of classically sampling the one-clean-qubit model with constant total variation distance error

    Science.gov (United States)

    Morimae, Tomoyuki

    2017-10-01

    The one-clean-qubit model (or the DQC1 model) is a restricted model of quantum computing where only a single input qubit is pure and all other input qubits are maximally mixed. In spite of the severe restriction, the model can solve several problems (such as calculating Jones polynomials) whose classical efficient solutions are not known. Furthermore, it was shown that if the output probability distribution of the one-clean-qubit model can be classically efficiently sampled with a constant multiplicative error, then the polynomial hierarchy collapses to the second level. Is it possible to improve the multiplicative error hardness result to a constant total variation distance error one like other subuniversal quantum computing models such as the IQP (Instantaneous Quantum Polynomial time) model, the boson sampling model, and the Fourier sampling model? In this paper we show that it is indeed possible if we accept a modified version of the average case hardness conjecture. Interestingly, the anticoncentration lemma can be easily shown by using the special property of the one-clean-qubit model that each output probability is so small that no concentration occurs.

  20. Randomized controlled trials 5: Determining the sample size and power for clinical trials and cohort studies.

    Science.gov (United States)

    Greene, Tom

    2015-01-01

    Performing well-powered randomized controlled trials is of fundamental importance in clinical research. The goal of sample size calculations is to assure that statistical power is acceptable while maintaining a small probability of a type I error. This chapter overviews the fundamentals of sample size calculation for standard types of outcomes for two-group studies. It considers (1) the problems of determining the size of the treatment effect that the studies will be designed to detect, (2) the modifications to sample size calculations to account for loss to follow-up and nonadherence, (3) the options when initial calculations indicate that the feasible sample size is insufficient to provide adequate power, and (4) the implication of using multiple primary endpoints. Sample size estimates for longitudinal cohort studies must take account of confounding by baseline factors.

  1. Characterization of Electron Microscopes with Binary Pseudo-random Multilayer Test Samples

    Energy Technology Data Exchange (ETDEWEB)

    V Yashchuk; R Conley; E Anderson; S Barber; N Bouet; W McKinney; P Takacs; D Voronov

    2011-12-31

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  2. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V., E-mail: VVYashchuk@lbl.gov [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Conley, Raymond [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States); Anderson, Erik H. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Barber, Samuel K. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Bouet, Nathalie [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States); McKinney, Wayne R. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Takacs, Peter Z. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Voronov, Dmitriy L. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2011-09-01

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  3. Image reconstruction from partial pseudo polar Fourier sampling based on alternating direction total variation minimization

    Science.gov (United States)

    Liu, Qiu-hong; Shu, Fan; Zhang, Wen-kun; Cai, Ai-long; Li, Lei; Yan, Bin

    2013-08-01

    Linear scan Computed Tomography (LCT) has emerged as a promising technique in fields like industrial scanning and security inspection due to its straight-line source trajectory and high scanning speed. However, in practical applications of LCT, the ordinary algorithms suffer from serious artifacts owing to the limited-angle and insufficient data. In this paper, a new method which reconstructs image from partial Fourier data sampled in pseudo polar grid based on alternating direction anisometric total variation minimization has been proposed. The main idea is to reform the image reconstruction problem into solving an under-determined linear equation, and then reconstruct image by applying the popular total variation (TV) minimization to reform an unconstraint optimization by means of augmented Lagrange method and using the alternating minimization method of multiplier (ADMM) which contributes to the fast convergence. The proposed method is practical in the large-scale task of reconstruction due to its algorithmic simplicity and computational efficiency and reconstructs better images. The results of the numerical simulations and pseudo real data reconstructions from the linear scan validate that the proposed method is both efficient and accurate.

  4. Spatial scales of variation in lichens: implications for sampling design in biomonitoring surveys.

    Science.gov (United States)

    Giordani, Paolo; Brunialti, Giorgio; Frati, Luisa; Incerti, Guido; Ianesch, Luca; Vallone, Emanuele; Bacaro, Giovanni; Maccherini, Simona

    2013-02-01

    The variability of biological data is a main constraint affecting the quality and reliability of lichen biomonitoring surveys for estimation of the effects of atmospheric pollution. Although most epiphytic lichen bioindication surveys focus on between-site differences at the landscape level, associated with the large scale effects of atmospheric pollution, current protocols are based on multilevel sampling, thus adding further sources of variation and affecting the error budget. We test the hypothesis that assemblages of lichen communities vary at each spatial scale examined, in order to determine what scales should be included in future monitoring studies. We compared four sites in Italy, along gradients of atmospheric pollution and climate, to test the partitioning of the variance components of lichen diversity across spatial scales (from trunks to landscapes). Despite environmental heterogeneity, we observed comparable spatial variance. However, residuals often overcame between-plot variability, leading to biased estimation of atmospheric pollution effects.

  5. Accounting for Sampling Error in Genetic Eigenvalues Using Random Matrix Theory.

    Science.gov (United States)

    Sztepanacz, Jacqueline L; Blows, Mark W

    2017-07-01

    The distribution of genetic variance in multivariate phenotypes is characterized by the empirical spectral distribution of the eigenvalues of the genetic covariance matrix. Empirical estimates of genetic eigenvalues from random effects linear models are known to be overdispersed by sampling error, where large eigenvalues are biased upward, and small eigenvalues are biased downward. The overdispersion of the leading eigenvalues of sample covariance matrices have been demonstrated to conform to the Tracy-Widom (TW) distribution. Here we show that genetic eigenvalues estimated using restricted maximum likelihood (REML) in a multivariate random effects model with an unconstrained genetic covariance structure will also conform to the TW distribution after empirical scaling and centering. However, where estimation procedures using either REML or MCMC impose boundary constraints, the resulting genetic eigenvalues tend not be TW distributed. We show how using confidence intervals from sampling distributions of genetic eigenvalues without reference to the TW distribution is insufficient protection against mistaking sampling error as genetic variance, particularly when eigenvalues are small. By scaling such sampling distributions to the appropriate TW distribution, the critical value of the TW statistic can be used to determine if the magnitude of a genetic eigenvalue exceeds the sampling error for each eigenvalue in the spectral distribution of a given genetic covariance matrix. Copyright © 2017 by the Genetics Society of America.

  6. On analysis-based two-step interpolation methods for randomly sampled seismic data

    Science.gov (United States)

    Yang, Pengliang; Gao, Jinghuai; Chen, Wenchao

    2013-02-01

    Interpolating the missing traces of regularly or irregularly sampled seismic record is an exceedingly important issue in the geophysical community. Many modern acquisition and reconstruction methods are designed to exploit the transform domain sparsity of the few randomly recorded but informative seismic data using thresholding techniques. In this paper, to regularize randomly sampled seismic data, we introduce two accelerated, analysis-based two-step interpolation algorithms, the analysis-based FISTA (fast iterative shrinkage-thresholding algorithm) and the FPOCS (fast projection onto convex sets) algorithm from the IST (iterative shrinkage-thresholding) algorithm and the POCS (projection onto convex sets) algorithm. A MATLAB package is developed for the implementation of these thresholding-related interpolation methods. Based on this package, we compare the reconstruction performance of these algorithms, using synthetic and real seismic data. Combined with several thresholding strategies, the accelerated convergence of the proposed methods is also highlighted.

  7. Hemodynamic and glucometabolic factors fail to predict renal function in a random population sample

    DEFF Research Database (Denmark)

    Pareek, M.; Nielsen, M.; Olesen, Thomas Bastholm

    2015-01-01

    Objective: To determine whether baseline hemodynamic and/or glucometabolic risk factors could predict renal function at follow-up, independently of baseline serum creatinine, in survivors from a random population sample. Design and method: We examined associations between baseline serum creatinine...... indices of beta-cell function (HOMA-2B), insulin sensitivity (HOMA-2S), and insulin resistance (HOMA-2IR)), traditional cardiovascular risk factors (age, sex, smoking status, body mass index, diabetes mellitus, total serum cholesterol), and later renal function determined as serum cystatin C in 238 men...... and 7 women aged 38 to 49 years at the time of inclusion, using multivariable linear regression analysis (p-entry 0.05, p-removal 0.20). Study subjects came from a random population based sample and were included 1974-1992, whilst the follow-up with cystatin C measurement was performed 2002...

  8. An inversion method based on random sampling for real-time MEG neuroimaging

    CERN Document Server

    Pascarella, Annalisa

    2016-01-01

    The MagnetoEncephaloGraphy (MEG) has gained great interest in neurorehabilitation training due to its high temporal resolution. The challenge is to localize the active regions of the brain in a fast and accurate way. In this paper we use an inversion method based on random spatial sampling to solve the real-time MEG inverse problem. Several numerical tests on synthetic but realistic data show that the method takes just a few hundredths of a second on a laptop to produce an accurate map of the electric activity inside the brain. Moreover, it requires very little memory storage. For this reasons the random sampling method is particularly attractive in real-time MEG applications.

  9. Modified Exponential Type Estimator for Population Mean Using Auxiliary Variables in Stratified Random Sampling

    OpenAIRE

    Özel, Gamze

    2015-01-01

    In this paper, a new exponential type estimator is developed in the stratified random sampling for the population mean using auxiliary variable information. In order to evaluate efficiency of the introduced estimator, we first review some estimators and study the optimum property of the suggested strategy. To judge the merits of the suggested class of estimators over others under the optimal condition, simulation study and real data applications are conducted. The results show that the introduc...

  10. Effectiveness of hand hygiene education among a random sample of women from the community

    OpenAIRE

    Ubheeram, J.; Biranjia-Hurdoyal, S.D.

    2017-01-01

    Summary Objective. The effectiveness of hand hygiene education was investigated by studying the hand hygiene awareness and bacterial hand contamination among a random sample of 170 women in the community. Methods. Questionnaire was used to assess the hand hygiene awareness score, followed by swabbing of the dominant hand. Bacterial identification was done by conventional biochemical tests. Results. Better hand hygiene awareness score was significantly associated with age, scarce bacterial gro...

  11. Control Capacity and A Random Sampling Method in Exploring Controllability of Complex Networks

    OpenAIRE

    Jia, Tao; Barab?si, Albert-L?szl?

    2013-01-01

    Controlling complex systems is a fundamental challenge of network science. Recent advances indicate that control over the system can be achieved through a minimum driver node set (MDS). The existence of multiple MDS's suggests that nodes do not participate in control equally, prompting us to quantify their participations. Here we introduce control capacity quantifying the likelihood that a node is a driver node. To efficiently measure this quantity, we develop a random sampling algorithm. Thi...

  12. Classification of epileptic EEG signals based on simple random sampling and sequential feature selection

    OpenAIRE

    Ghayab, Hadi Ratham Al; Li, Yan; Abdulla, Shahab; Diykh, Mohammed; Wan, Xiangkui

    2016-01-01

    Electroencephalogram (EEG) signals are used broadly in the medical fields. The main applications of EEG signals are the diagnosis and treatment of diseases such as epilepsy, Alzheimer, sleep problems and so on. This paper presents a new method which extracts and selects features from multi-channel EEG signals. This research focuses on three main points. Firstly, simple random sampling (SRS) technique is used to extract features from the time domain of EEG signals. Secondly, the sequential fea...

  13. Precision of systematic and random sampling in clustered populations: habitat patches and aggregating organisms.

    Science.gov (United States)

    McGarvey, Richard; Burch, Paul; Matthews, Janet M

    2016-01-01

    Natural populations of plants and animals spatially cluster because (1) suitable habitat is patchy, and (2) within suitable habitat, individuals aggregate further into clusters of higher density. We compare the precision of random and systematic field sampling survey designs under these two processes of species clustering. Second, we evaluate the performance of 13 estimators for the variance of the sample mean from a systematic survey. Replicated simulated surveys, as counts from 100 transects, allocated either randomly or systematically within the study region, were used to estimate population density in six spatial point populations including habitat patches and Matérn circular clustered aggregations of organisms, together and in combination. The standard one-start aligned systematic survey design, a uniform 10 x 10 grid of transects, was much more precise. Variances of the 10 000 replicated systematic survey mean densities were one-third to one-fifth of those from randomly allocated transects, implying transect sample sizes giving equivalent precision by random survey would need to be three to five times larger. Organisms being restricted to patches of habitat was alone sufficient to yield this precision advantage for the systematic design. But this improved precision for systematic sampling in clustered populations is underestimated by standard variance estimators used to compute confidence intervals. True variance for the survey sample mean was computed from the variance of 10 000 simulated survey mean estimates. Testing 10 published and three newly proposed variance estimators, the two variance estimators (v) that corrected for inter-transect correlation (ν₈ and ν(W)) were the most accurate and also the most precise in clustered populations. These greatly outperformed the two "post-stratification" variance estimators (ν₂ and ν₃) that are now more commonly applied in systematic surveys. Similar variance estimator performance rankings were found with

  14. Determining optimal sample sizes for multi-stage randomized clinical trials using value of information methods.

    Science.gov (United States)

    Willan, Andrew; Kowgier, Matthew

    2008-01-01

    Traditional sample size calculations for randomized clinical trials depend on somewhat arbitrarily chosen factors, such as Type I and II errors. An effectiveness trial (otherwise known as a pragmatic trial or management trial) is essentially an effort to inform decision-making, i.e., should treatment be adopted over standard? Taking a societal perspective and using Bayesian decision theory, Willan and Pinto (Stat. Med. 2005; 24:1791-1806 and Stat. Med. 2006; 25:720) show how to determine the sample size that maximizes the expected net gain, i.e., the difference between the cost of doing the trial and the value of the information gained from the results. These methods are extended to include multi-stage adaptive designs, with a solution given for a two-stage design. The methods are applied to two examples. As demonstrated by the two examples, substantial increases in the expected net gain (ENG) can be realized by using multi-stage adaptive designs based on expected value of information methods. In addition, the expected sample size and total cost may be reduced. Exact solutions have been provided for the two-stage design. Solutions for higher-order designs may prove to be prohibitively complex and approximate solutions may be required. The use of multi-stage adaptive designs for randomized clinical trials based on expected value of sample information methods leads to substantial gains in the ENG and reductions in the expected sample size and total cost.

  15. Sample size calculations for pilot randomized trials: a confidence interval approach.

    Science.gov (United States)

    Cocks, Kim; Torgerson, David J

    2013-02-01

    To describe a method using confidence intervals (CIs) to estimate the sample size for a pilot randomized trial. Using one-sided CIs and the estimated effect size that would be sought in a large trial, we calculated the sample size needed for pilot trials. Using an 80% one-sided CI, we estimated that a pilot trial should have at least 9% of the sample size of the main planned trial. Using the estimated effect size difference for the main trial and using a one-sided CI, this allows us to calculate a sample size for a pilot trial, which will make its results more useful than at present. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Heating-induced variations of secondary electron emission from ion-cleaned copper samples.

    Science.gov (United States)

    Hu, Xiao-Chuan; Zhang, Hai-Bo; Cao, Meng; Zhang, Na; Cui, Wan-Zhao

    2014-09-01

    Secondary electron (SE) emission due to electron impact depends strongly on surface conditions. The variations of SE yield and spectrum with the heating temperature of Ar-ion-cleaned oxygen-free copper samples are therefore measured in situ in a multifunctional ultrahigh vacuum system. The SE yield and the SE spectrum are observed to increase and to narrow, respectively, after sample heating. The maximum SE yield increases from 0.97 before heating to 1.25 after heating at ∼313 °C, and the corresponding full width at half maximum of SE spectrum decreases considerably from 9.3 to 5.5 eV. More CO2 and Ar ions are shown to desorb at a higher heating temperature by residual gas analysis, indicating their contribution to the reduction in work function and surface potential barrier. Ar-ion desorption appears to affect the SE spectrum more than the SE yield. The obtained results provide a new insight into complicated surface influences on SE emission in thermal applications of scanning electron microscopy. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. The Efficiency of Variance Reduction in Manufacturing and Service Systems: The Comparison of the Control Variates and Stratified Sampling

    Directory of Open Access Journals (Sweden)

    Ergün Eraslan

    2009-01-01

    Full Text Available There has been a great interest in the use of variance reduction techniques (VRTs in simulation output analysis for the purpose of improving accuracy when the performance measurements of complex production and service systems are estimated. Therefore, a simulation output analysis to improve the accuracy and reliability of the output is required. The performance measurements are required to have a narrow and strong confidence interval. For a given confidence level, a smaller confidence interval is supposed to be better than the larger one. The wide of confidence interval, determined by the half length, will depend on the variance. Generally, increased replication of the simulation model appears to have been the easiest way to reduce variance but this increases the simulation costs in complex-structured and large-sized manufacturing and service systems. Thus, VRTs are used in experiments to avoid computational cost of decision-making processes for more precise results. In this study, the effect of Control Variates (CVs and Stratified Sampling (SS techniques in reducing variance of the performance measurements of M/M/1 and GI/G/1 queue models is investigated considering four probability distributions utilizing randomly generated parameters for arrival and service processes.

  18. Random variation in voluntary dry matter intake and effect of day length on feed intake capacity in growing cattle

    DEFF Research Database (Denmark)

    Ingvartsen, Klaus Lønne; Andersen, Refsgaard; Foldager, John

    1992-01-01

    in fifteen bulls, steers and heifers, respectively, fed a complete diet ad libitum. The diet was based on chopped straw formulated to secure physical regulation of feed intake. Total random variation of recorded VDMI corresponded to a coefficient of variation (CV) of 24.6%. Two thirds of this variation...... was increased by 0.32% per hour increase in day length. This is in agreement with the increase found in reviewed literature when photoperiod was manipulated artificially. Practical application of the results for monitoring purposes are exemplified and discussed....

  19. Overcoming sampling depth variations in the analysis of broadband hyperspectral images of breast tissue (Conference Presentation)

    Science.gov (United States)

    Kho, Esther; de Boer, Lisanne L.; Van de Vijver, Koen K.; Sterenborg, Henricus J. C. M.; Ruers, Theo J. M.

    2017-02-01

    Worldwide, up to 40% of the breast conserving surgeries require additional operations due to positive resection margins. We propose to reduce this percentage by using hyperspectral imaging for resection margin assessment during surgery. Spectral hypercubes were collected from 26 freshly excised breast specimens with a pushbroom camera (900-1700nm). Computer simulations of the penetration depth in breast tissue suggest a strong variation in sampling depth ( 0.5-10 mm) over this wavelength range. This was confirmed with a breast tissue mimicking phantom study. Smaller penetration depths are observed in wavelength regions with high water and/or fat absorption. Consequently, tissue classification based on spectral analysis over the whole wavelength range becomes complicated. This is especially a problem in highly inhomogeneous human tissue. We developed a method, called derivative imaging, which allows accurate tissue analysis, without the impediment of dissimilar sampling volumes. A few assumptions were made based on previous research. First, the spectra acquired with our camera from breast tissue are mainly shaped by fat and water absorption. Second, tumor tissue contains less fat and more water than healthy tissue. Third, scattering slopes of different tissue types are assumed to be alike. In derivative imaging, the derivatives are calculated of wavelengths a few nanometers apart; ensuring similar penetration depths. The wavelength choice determines the accuracy of the method and the resolution. Preliminary results on 3 breast specimens indicate a classification accuracy of 93% when using wavelength regions characterized by water and fat absorption. The sampling depths at these regions are 1mm and 5mm.

  20. Estimating the Size of a Large Network and its Communities from a Random Sample.

    Science.gov (United States)

    Chen, Lin; Karbasi, Amin; Crawford, Forrest W

    2016-01-01

    Most real-world networks are too large to be measured or studied directly and there is substantial interest in estimating global network properties from smaller sub-samples. One of the most important global properties is the number of vertices/nodes in the network. Estimating the number of vertices in a large network is a major challenge in computer science, epidemiology, demography, and intelligence analysis. In this paper we consider a population random graph G = (V, E) from the stochastic block model (SBM) with K communities/blocks. A sample is obtained by randomly choosing a subset W ⊆ V and letting G(W) be the induced subgraph in G of the vertices in W. In addition to G(W), we observe the total degree of each sampled vertex and its block membership. Given this partial information, we propose an efficient PopULation Size Estimation algorithm, called PULSE, that accurately estimates the size of the whole population as well as the size of each community. To support our theoretical analysis, we perform an exhaustive set of experiments to study the effects of sample size, K, and SBM model parameters on the accuracy of the estimates. The experimental results also demonstrate that PULSE significantly outperforms a widely-used method called the network scale-up estimator in a wide variety of scenarios.

  1. Design of Energy Aware Adder Circuits Considering Random Intra-Die Process Variations

    Directory of Open Access Journals (Sweden)

    Marco Lanuzza

    2011-04-01

    Full Text Available Energy consumption is one of the main barriers to current high-performance designs. Moreover, the increased variability experienced in advanced process technologies implies further timing yield concerns and therefore intensifies this obstacle. Thus, proper techniques to achieve robust designs are a critical requirement for integrated circuit success. In this paper, the influence of intra-die random process variations is analyzed considering the particular case of the design of energy aware adder circuits. Five well known adder circuits were designed exploiting an industrial 45 nm static complementary metal-oxide semiconductor (CMOS standard cell library. The designed adders were comparatively evaluated under different energy constraints. As a main result, the performed analysis demonstrates that, for a given energy budget, simpler circuits (which are conventionally identified as low-energy slow architectures operating at higher power supply voltages can achieve a timing yield significantly better than more complex faster adders when used in low-power design with supply voltages lower than nominal.

  2. Evaluation of sampling systems in iron ore concentrating and pelletizing processes - quantification of total sampling error (TSE) vs. apparent process variation

    DEFF Research Database (Denmark)

    Engström, Karin; Esbensen, Kim Harry

    2018-01-01

    Process sampling is involved in grade control in all parts of the production value chain in mineral processing. Reliable sampling and assaying is essential to ensure final product quality, but the need for representative sampling is not always taken into account. By continuous control...... analyses will form a basis for suggestions of possible improvements. The results show that variographic analysis is a powerful tool to evaluate both process variations and the variability of the sampling systems employed. The extensive access to time series data allow variographic characterization (quality...... control) of all critical measurement systems and locations. At the same time, periodicity and small changes in process variation can be detected and counteracted early, minimizing the risk for producing products out of specification....

  3. Peer Effects and Measurement Error: The Impact of Sampling Variation in School Survey Data (Evidence from PISA)

    Science.gov (United States)

    Micklewright, John; Schnepf, Sylke V.; Silva, Pedro N.

    2012-01-01

    Investigation of peer effects on achievement with sample survey data on schools may mean that only a random sample of the population of peers is observed for each individual. This generates measurement error in peer variables similar in form to the textbook case of errors-in-variables, resulting in the estimated peer group effects in an OLS…

  4. Nicotine therapy sampling to induce quit attempts among smokers unmotivated to quit: a randomized clinical trial.

    Science.gov (United States)

    Carpenter, Matthew J; Hughes, John R; Gray, Kevin M; Wahlquist, Amy E; Saladin, Michael E; Alberg, Anthony J

    2011-11-28

    Rates of smoking cessation have not changed in a decade, accentuating the need for novel approaches to prompt quit attempts. Within a nationwide randomized clinical trial (N = 849) to induce further quit attempts and cessation, smokers currently unmotivated to quit were randomized to a practice quit attempt (PQA) alone or to nicotine replacement therapy (hereafter referred to as nicotine therapy), sampling within the context of a PQA. Following a 6-week intervention period, participants were followed up for 6 months to assess outcomes. The PQA intervention was designed to increase motivation, confidence, and coping skills. The combination of a PQA plus nicotine therapy sampling added samples of nicotine lozenges to enhance attitudes toward pharmacotherapy and to promote the use of additional cessation resources. Primary outcomes included the incidence of any ever occurring self-defined quit attempt and 24-hour quit attempt. Secondary measures included 7-day point prevalence abstinence at any time during the study (ie, floating abstinence) and at the final follow-up assessment. Compared with PQA intervention, nicotine therapy sampling was associated with a significantly higher incidence of any quit attempt (49% vs 40%; relative risk [RR], 1.2; 95% CI, 1.1-1.4) and any 24-hour quit attempt (43% vs 34%; 1.3; 1.1-1.5). Nicotine therapy sampling was marginally more likely to promote floating abstinence (19% vs 15%; RR, 1.3; 95% CI, 1.0-1.7); 6-month point prevalence abstinence rates were no different between groups (16% vs 14%; 1.2; 0.9-1.6). Nicotine therapy sampling during a PQA represents a novel strategy to motivate smokers to make a quit attempt. clinicaltrials.gov Identifier: NCT00706979.

  5. Location and multi-depot vehicle routing for emergency vehicles using tour coverage and random sampling

    Directory of Open Access Journals (Sweden)

    Alireza Goli

    2015-09-01

    Full Text Available Distribution and optimum allocation of emergency resources are the most important tasks, which need to be accomplished during crisis. When a natural disaster such as earthquake, flood, etc. takes place, it is necessary to deliver rescue efforts as quickly as possible. Therefore, it is important to find optimum location and distribution of emergency relief resources. When a natural disaster occurs, it is not possible to reach some damaged areas. In this paper, location and multi-depot vehicle routing for emergency vehicles using tour coverage and random sampling is investigated. In this study, there is no need to visit all the places and some demand points receive their needs from the nearest possible location. The proposed study is implemented for some randomly generated numbers in different sizes. The preliminary results indicate that the proposed method was capable of reaching desirable solutions in reasonable amount of time.

  6. ESTIMATION OF FINITE POPULATION MEAN USING RANDOM NON–RESPONSE IN SURVEY SAMPLING

    Directory of Open Access Journals (Sweden)

    Housila P. Singh

    2010-12-01

    Full Text Available This paper consider the problem of estimating the population mean under three different situations of random non–response envisaged by Singh et al (2000. Some ratio and product type estimators have been proposed and their properties are studied under an assumption that the number of sampling units on which information can not be obtained owing to random non–response follows some distribution. The suggested estimators are compared with the usual ratio and product estimators. An empirical study is carried out to show the performance of the suggested estimators over usual unbiased estimator, ratio and product estimators. A generalized version of the proposed ratio and product estimators is also given.

  7. Estimation of the Coefficient of Variation with Minimum Risk: A Sequential Method for Minimizing Sampling Error and Study Cost.

    Science.gov (United States)

    Chattopadhyay, Bhargab; Kelley, Ken

    2016-01-01

    The coefficient of variation is an effect size measure with many potential uses in psychology and related disciplines. We propose a general theory for a sequential estimation of the population coefficient of variation that considers both the sampling error and the study cost, importantly without specific distributional assumptions. Fixed sample size planning methods, commonly used in psychology and related fields, cannot simultaneously minimize both the sampling error and the study cost. The sequential procedure we develop is the first sequential sampling procedure developed for estimating the coefficient of variation. We first present a method of planning a pilot sample size after the research goals are specified by the researcher. Then, after collecting a sample size as large as the estimated pilot sample size, a check is performed to assess whether the conditions necessary to stop the data collection have been satisfied. If not an additional observation is collected and the check is performed again. This process continues, sequentially, until a stopping rule involving a risk function is satisfied. Our method ensures that the sampling error and the study costs are considered simultaneously so that the cost is not higher than necessary for the tolerable sampling error. We also demonstrate a variety of properties of the distribution of the final sample size for five different distributions under a variety of conditions with a Monte Carlo simulation study. In addition, we provide freely available functions via the MBESS package in R to implement the methods discussed.

  8. Chi-Squared Test of Fit and Sample Size-A Comparison between a Random Sample Approach and a Chi-Square Value Adjustment Method.

    Science.gov (United States)

    Bergh, Daniel

    2015-01-01

    Chi-square statistics are commonly used for tests of fit of measurement models. Chi-square is also sensitive to sample size, which is why several approaches to handle large samples in test of fit analysis have been developed. One strategy to handle the sample size problem may be to adjust the sample size in the analysis of fit. An alternative is to adopt a random sample approach. The purpose of this study was to analyze and to compare these two strategies using simulated data. Given an original sample size of 21,000, for reductions of sample sizes down to the order of 5,000 the adjusted sample size function works as good as the random sample approach. In contrast, when applying adjustments to sample sizes of lower order the adjustment function is less effective at approximating the chi-square value for an actual random sample of the relevant size. Hence, the fit is exaggerated and misfit under-estimated using the adjusted sample size function. Although there are big differences in chi-square values between the two approaches at lower sample sizes, the inferences based on the p-values may be the same.

  9. Randomized controlled trial on timing and number of sampling for bile aspiration cytology.

    Science.gov (United States)

    Tsuchiya, Tomonori; Yokoyama, Yukihiro; Ebata, Tomoki; Igami, Tsuyoshi; Sugawara, Gen; Kato, Katsuyuki; Shimoyama, Yoshie; Nagino, Masato

    2014-06-01

    The issue on timing and number of bile sampling for exfoliative bile cytology is still unsettled. A total of 100 patients with cholangiocarcinoma undergoing resection after external biliary drainage were randomized into two groups: a 2-day group where bile was sampled five times per day for 2 days; and a 10-day group where bile was sampled once per day for 10 days (registered University Hospital Medical Information Network/ID 000005983). The outcome of 87 patients who underwent laparotomy was analyzed, 44 in the 2-day group and 43 in the 10-day group. There were no significant differences in patient characteristics between the two groups. Positivity after one sampling session was significantly lower in the 2-day group than in the 10-day group (17.0 ± 3.7% vs. 20.7 ± 3.5%, P = 0.034). However, cumulative positivity curves were similar and overlapped each other between both groups. The final cumulative positivity by the 10th sampling session was 52.3% in the 2-day group and 51.2% in the 10-day group. We observed a small increase in cumulative positivity after the 5th or 6th session in both groups. Bile cytology positivity is unlikely to be affected by sample time. © 2013 Japanese Society of Hepato-Biliary-Pancreatic Surgery.

  10. Estimating the Size of a Large Network and its Communities from a Random Sample

    CERN Document Server

    Chen, Lin; Crawford, Forrest W

    2016-01-01

    Most real-world networks are too large to be measured or studied directly and there is substantial interest in estimating global network properties from smaller sub-samples. One of the most important global properties is the number of vertices/nodes in the network. Estimating the number of vertices in a large network is a major challenge in computer science, epidemiology, demography, and intelligence analysis. In this paper we consider a population random graph G = (V;E) from the stochastic block model (SBM) with K communities/blocks. A sample is obtained by randomly choosing a subset W and letting G(W) be the induced subgraph in G of the vertices in W. In addition to G(W), we observe the total degree of each sampled vertex and its block membership. Given this partial information, we propose an efficient PopULation Size Estimation algorithm, called PULSE, that correctly estimates the size of the whole population as well as the size of each community. To support our theoretical analysis, we perform an exhausti...

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

    Science.gov (United States)

    Sree, David

    1992-01-01

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

  12. Prevalence and correlates of problematic smartphone use in a large random sample of Chinese undergraduates.

    Science.gov (United States)

    Long, Jiang; Liu, Tie-Qiao; Liao, Yan-Hui; Qi, Chang; He, Hao-Yu; Chen, Shu-Bao; Billieux, Joël

    2016-11-17

    Smartphones are becoming a daily necessity for most undergraduates in Mainland China. Because the present scenario of problematic smartphone use (PSU) is largely unexplored, in the current study we aimed to estimate the prevalence of PSU and to screen suitable predictors for PSU among Chinese undergraduates in the framework of the stress-coping theory. A sample of 1062 undergraduate smartphone users was recruited by means of the stratified cluster random sampling strategy between April and May 2015. The Problematic Cellular Phone Use Questionnaire was used to identify PSU. We evaluated five candidate risk factors for PSU by using logistic regression analysis while controlling for demographic characteristics and specific features of smartphone use. The prevalence of PSU among Chinese undergraduates was estimated to be 21.3%. The risk factors for PSU were majoring in the humanities, high monthly income from the family (≥1500 RMB), serious emotional symptoms, high perceived stress, and perfectionism-related factors (high doubts about actions, high parental expectations). PSU among undergraduates appears to be ubiquitous and thus constitutes a public health issue in Mainland China. Although further longitudinal studies are required to test whether PSU is a transient phenomenon or a chronic and progressive condition, our study successfully identified socio-demographic and psychological risk factors for PSU. These results, obtained from a random and thus representative sample of undergraduates, opens up new avenues in terms of prevention and regulation policies.

  13. Variation in the human lymphocyte sister chromatid exchange frequency as a function of time: results of daily and twice-weekly sampling

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, J.D.; Christensen, M.L.; Strout, C.L.; McGee, K.A.; Carrano, A.V.

    1987-01-01

    The variation in lymphocyte sister chromatid exchange (SCE) frequency was investigated in healthy nonsmokers who were not taking any medication. Two separate studies were undertaken. In the first, blood was drawn from four women twice a week for 8 weeks. These donors recorded the onset and termination of menstruation and times of illness. In the second study, blood was obtained from two women and two men for 5 consecutive days on two separate occasions initiated 14 days apart. Analysis of the mean SCE frequencies in each study indicated that significant temporal variation occurred in each donor, and that more variation occurred in the longer study. Some of the variation was found to be associated with the menstrual cycle. In the daily study, most of the variation appeared to be random, but occasional day-to-day changes occurred that were greater than those expected by chance. To determine how well a single SCE sample estimated the pooled mean for each donor in each study, the authors calculated the number of samples that encompassed that donor's pooled mean within 1 or more standard errors. For both studies, about 75% of the samples encompassed the pooled mean within 2 standard errors. An analysis of high-frequency cells (HFCs) was also undertaken. The results for each study indicate that the proportion of HFCs, compared with the use of Fisher's Exact test, is significantly more constant than the means, which were compared by using the t-test. These results coupled with our previous work suggest that HFC analysis may be the method of choice when analyzing data from human population studies.

  14. Analytical and between-subject variation of thrombin generation measured by calibrated automated thrombography on plasma samples.

    Science.gov (United States)

    Kristensen, Anne F; Kristensen, Søren R; Falkmer, Ursula; Münster, Anna-Marie B; Pedersen, Shona

    2018-01-16

    The Calibrated Automated Thrombography (CAT) is an in vitro thrombin generation (TG) assay that holds promise as a valuable tool within clinical diagnostics. However, the technique has a considerable analytical variation, and we therefore, investigated the analytical and between-subject variation of CAT systematically. Moreover, we assess the application of an internal standard for normalization to diminish variation. 20 healthy volunteers donated one blood sample which was subsequently centrifuged, aliquoted and stored at -80 °C prior to analysis. The analytical variation was determined on eight runs, where plasma from the same seven volunteers was processed in triplicates, and for the between-subject variation, TG analysis was performed on plasma from all 20 volunteers. The trigger reagents used for the TG assays included both PPP reagent containing 5 pM tissue factor (TF) and PPPlow with 1 pM TF. Plasma, drawn from a single donor, was applied to all plates as an internal standard for each TG analysis, which subsequently was used for normalization. The total analytical variation for TG analysis performed with PPPlow reagent is 3-14% and 9-13% for PPP reagent. This variation can be minimally reduced by using an internal standard but mainly for ETP (endogenous thrombin potential). The between-subject variation is higher when using PPPlow than PPP and this variation is considerable higher than the analytical variation. TG has a rather high inherent analytical variation but considerable lower than the between-subject variation when using PPPlow as reagent.

  15. Reproductive Fitness and Random Amplified Polymorphic DNA Variation among Isolates of Pratylenchus vulnus.

    Science.gov (United States)

    Pinochet, P; Cenis, J L; Fernández, C; Doucet, M; Maruli, J

    1994-09-01

    The reproductive fitness of seven isolates of Pratylenchus vulnus from different geographical areas and hosts was assessed in monoxenic cultures (carrot), and greenhouse cultures (plum, sour orange, and quince). The genetic makeup of the different isolates was compared by Random Amplified Polymorphic DNA (RAPD-PCR). The apple (PvAP-S) and apricot (PvAT-F) isolates reproduced less in monoxenic cultures than the rose (PvRO-S) and walnut (PvWA-A and PvWA-U) isolates. On plum, the rose isolate (PvRO-S) reproduced better than the apple (PvAP-S) and walnut isolate from the United States (PvWA-U). On sour orange, the apple (PvAP-S), unknown origin (PvU-UK), and walnut isolate from Argentina (PvWA-A) multiplied well, whereas the walnut isolate from the United States (PvWA-U), apricot (PvAT-F), and rose (PvRO-S) did not. On quince, the apple (PvAP-S) and walnut (PvWA-U) isolates showed a higher reproduction than the one from unknown origin (PvU-UK). RAPD-PCR patterns among the seven P. vulnus isolates were similar, although high intraspecific varibility was detected. Very few bands of P. neglectus were shared by any population of P. vulnus. A high degree of similarity was found among the patterns corresponding to the rose (PvRO-S), apple (PvAP-S), walnut from the United States (PvWA-U), and unknown origin (PvUK-U) isolates. The apricot isolate (PvAT-F) was the most dissimilar among the seven isolates. No correlation could be established between the genetic variation of P. vulnus detected by RAPD-PCR and reproductive fitness. Results demonstrate high genetic varibility between geographically separated populations of P. vulnus.

  16. Protein/creatinine ratio on random urine samples for prediction of proteinuria in preeclampsia.

    Science.gov (United States)

    Roudsari, F Vahid; Ayati, S; Ayatollahi, H; Shakeri, M T

    2012-01-01

    To evaluate Protein/Creatinine ratio on random urine samples for prediction of proteinuria in preeclampsia. This study was performed on 150 pregnant women who were hospitalized as preeclampsia in Ghaem Hospital during 2006. At first, a 24-hours urine sample was collected for each patient to determine protein/creatinine ratio. Then, 24-hours urine collection was analyzed for the evaluation of proteinuria. Statistical analysis was performed with SPSS software. A total of 150 patients entered the study. There was a significant relation between the 24-hours urine protein and protein/creatinine ratio (r = 0.659, P < 0.001). Since the measurement of protein/creatinine ratio is more accurate, reliable, and cost-effective, it can be replaced by the method of measurement the 24-hours urine protein.

  17. Random phenotypic variation of yeast (Saccharomyces cerevisiae) single-gene knockouts fits a double pareto-lognormal distribution.

    Science.gov (United States)

    Graham, John H; Robb, Daniel T; Poe, Amy R

    2012-01-01

    Distributed robustness is thought to influence the buffering of random phenotypic variation through the scale-free topology of gene regulatory, metabolic, and protein-protein interaction networks. If this hypothesis is true, then the phenotypic response to the perturbation of particular nodes in such a network should be proportional to the number of links those nodes make with neighboring nodes. This suggests a probability distribution approximating an inverse power-law of random phenotypic variation. Zero phenotypic variation, however, is impossible, because random molecular and cellular processes are essential to normal development. Consequently, a more realistic distribution should have a y-intercept close to zero in the lower tail, a mode greater than zero, and a long (fat) upper tail. The double Pareto-lognormal (DPLN) distribution is an ideal candidate distribution. It consists of a mixture of a lognormal body and upper and lower power-law tails. If our assumptions are true, the DPLN distribution should provide a better fit to random phenotypic variation in a large series of single-gene knockout lines than other skewed or symmetrical distributions. We fit a large published data set of single-gene knockout lines in Saccharomyces cerevisiae to seven different probability distributions: DPLN, right Pareto-lognormal (RPLN), left Pareto-lognormal (LPLN), normal, lognormal, exponential, and Pareto. The best model was judged by the Akaike Information Criterion (AIC). Phenotypic variation among gene knockouts in S. cerevisiae fits a double Pareto-lognormal (DPLN) distribution better than any of the alternative distributions, including the right Pareto-lognormal and lognormal distributions. A DPLN distribution is consistent with the hypothesis that developmental stability is mediated, in part, by distributed robustness, the resilience of gene regulatory, metabolic, and protein-protein interaction networks. Alternatively, multiplicative cell growth, and the mixing of

  18. Variation in orgasm occurrence by sexual orientation in a sample of U.S. singles.

    Science.gov (United States)

    Garcia, Justin R; Lloyd, Elisabeth A; Wallen, Kim; Fisher, Helen E

    2014-11-01

    Despite recent advances in understanding orgasm variation, little is known about ways in which sexual orientation is associated with men's and women's orgasm occurrence. To assess orgasm occurrence during sexual activity across sexual orientation categories. Data were collected by Internet questionnaire from 6,151 men and women (ages 21-65+ years) as part of a nationally representative sample of single individuals in the United States. Analyses were restricted to a subsample of 2,850 singles (1,497 men, 1,353 women) who had experienced sexual activity in the past 12 months. Participants reported their sex/gender, self-identified sexual orientation (heterosexual, gay/lesbian, bisexual), and what percentage of the time they experience orgasm when having sex with a familiar partner. Mean occurrence rate for experiencing orgasm during sexual activity with a familiar partner was 62.9% among single women and 85.1% among single men, which was significantly different (F1,2848  = 370.6, P orgasm did not vary by sexual orientation: heterosexual men 85.5%, gay men 84.7%, bisexual men 77.6% (F2,1494  = 2.67, P = 0.07, η(2)  = 0.004). For women, however, mean occurrence rate of orgasm varied significantly by sexual orientation: heterosexual women 61.6%, lesbian women 74.7%, bisexual women 58.0% (F2,1350  = 10.95, P women had a significantly higher probability of orgasm than did either heterosexual or bisexual women (P women, regardless of sexual orientation, have less predictable, more varied orgasm experiences than do men and that for women, but not men, the likelihood of orgasm varies with sexual orientation. These findings demonstrate the need for further investigations into the comparative sexual experiences and sexual health outcomes of sexual minorities. © 2014 International Society for Sexual Medicine.

  19. A Combined Weighting Method Based on Hybrid of Interval Evidence Fusion and Random Sampling

    Directory of Open Access Journals (Sweden)

    Ying Yan

    2017-01-01

    Full Text Available Due to the complexity of system and lack of expertise, epistemic uncertainties may present in the experts’ judgment on the importance of certain indices during group decision-making. A novel combination weighting method is proposed to solve the index weighting problem when various uncertainties are present in expert comments. Based on the idea of evidence theory, various types of uncertain evaluation information are uniformly expressed through interval evidence structures. Similarity matrix between interval evidences is constructed, and expert’s information is fused. Comment grades are quantified using the interval number, and cumulative probability function for evaluating the importance of indices is constructed based on the fused information. Finally, index weights are obtained by Monte Carlo random sampling. The method can process expert’s information with varying degrees of uncertainties, which possesses good compatibility. Difficulty in effectively fusing high-conflict group decision-making information and large information loss after fusion is avertible. Original expert judgments are retained rather objectively throughout the processing procedure. Cumulative probability function constructing and random sampling processes do not require any human intervention or judgment. It can be implemented by computer programs easily, thus having an apparent advantage in evaluation practices of fairly huge index systems.

  20. A descriptive analysis of a representative sample of pediatric randomized controlled trials published in 2007

    Directory of Open Access Journals (Sweden)

    Thomson Denise

    2010-12-01

    Full Text Available Abstract Background Randomized controlled trials (RCTs are the gold standard for trials assessing the effects of therapeutic interventions; therefore it is important to understand how they are conducted. Our objectives were to provide an overview of a representative sample of pediatric RCTs published in 2007 and assess the validity of their results. Methods We searched Cochrane Central Register of Controlled Trials using a pediatric filter and randomly selected 300 RCTs published in 2007. We extracted data on trial characteristics; outcomes; methodological quality; reporting; and registration and protocol characteristics. Trial registration and protocol availability were determined for each study based on the publication, an Internet search and an author survey. Results Most studies (83% were efficacy trials, 40% evaluated drugs, and 30% were placebo-controlled. Primary outcomes were specified in 41%; 43% reported on adverse events. At least one statistically significant outcome was reported in 77% of trials; 63% favored the treatment group. Trial registration was declared in 12% of publications and 23% were found through an Internet search. Risk of bias (ROB was high in 59% of trials, unclear in 33%, and low in 8%. Registered trials were more likely to have low ROB than non-registered trials (16% vs. 5%; p = 0.008. Effect sizes tended to be larger for trials at high vs. low ROB (0.28, 95% CI 0.21,0.35 vs. 0.16, 95% CI 0.07,0.25. Among survey respondents (50% response rate, the most common reason for trial registration was a publication requirement and for non-registration, a lack of familiarity with the process. Conclusions More than half of this random sample of pediatric RCTs published in 2007 was at high ROB and three quarters of trials were not registered. There is an urgent need to improve the design, conduct, and reporting of child health research.

  1. Short communication: Influence of the sampling device on somatic cell count variation in cow milk samples (by official recording)

    Energy Technology Data Exchange (ETDEWEB)

    Fouz, R.; Vilar, M.J.; Yus, E.; Sanjuán, M.L.; Diéguez, F.J.

    2016-11-01

    The objective of this study was to investigate the variability in cow´s milk somatic cell counts (SCC) depending on the type of milk meter used by dairy farms for official milk recording. The study was performed in 2011 and 2012 in the major cattle area of Spain. In total, 137,846 lactations of Holstein-Friesian cows were analysed at 1,912 farms. A generalised least squares regression model was used for data analysis. The model showed that the milk meter had a substantial effect on the SCC for individual milk samples obtained for official milk recording. The results suggested an overestimation of the SCC in milk samples from farms that had electronic devices in comparison with farms that used portable devices and underestimation when volumetric meters are used. A weak positive correlation was observed between the SCC and the percentage of fat in individual milk samples. The results underline the importance of considering this variable when using SCC data from milk recording in the dairy herd improvement program or in quality milk programs. (Author)

  2. Cost-effective sampling of ¹³⁷Cs-derived net soil redistribution: part 1--estimating the spatial mean across scales of variation.

    Science.gov (United States)

    Li, Y; Chappell, A; Nyamdavaa, B; Yu, H; Davaasuren, D; Zoljargal, K

    2015-03-01

    The (137)Cs technique for estimating net time-integrated soil redistribution is valuable for understanding the factors controlling soil redistribution by all processes. The literature on this technique is dominated by studies of individual fields and describes its typically time-consuming nature. We contend that the community making these studies has inappropriately assumed that many (137)Cs measurements are required and hence estimates of net soil redistribution can only be made at the field scale. Here, we support future studies of (137)Cs-derived net soil redistribution to apply their often limited resources across scales of variation (field, catchment, region etc.) without compromising the quality of the estimates at any scale. We describe a hybrid, design-based and model-based, stratified random sampling design with composites to estimate the sampling variance and a cost model for fieldwork and laboratory measurements. Geostatistical mapping of net (1954-2012) soil redistribution as a case study on the Chinese Loess Plateau is compared with estimates for several other sampling designs popular in the literature. We demonstrate the cost-effectiveness of the hybrid design for spatial estimation of net soil redistribution. To demonstrate the limitations of current sampling approaches to cut across scales of variation, we extrapolate our estimate of net soil redistribution across the region, show that for the same resources, estimates from many fields could have been provided and would elucidate the cause of differences within and between regional estimates. We recommend that future studies evaluate carefully the sampling design to consider the opportunity to investigate (137)Cs-derived net soil redistribution across scales of variation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Inflammatory Biomarkers and Risk of Schizophrenia: A 2-Sample Mendelian Randomization Study.

    Science.gov (United States)

    Hartwig, Fernando Pires; Borges, Maria Carolina; Horta, Bernardo Lessa; Bowden, Jack; Davey Smith, George

    2017-12-01

    Positive associations between inflammatory biomarkers and risk of psychiatric disorders, including schizophrenia, have been reported in observational studies. However, conventional observational studies are prone to bias, such as reverse causation and residual confounding, thus limiting our understanding of the effect (if any) of inflammatory biomarkers on schizophrenia risk. To evaluate whether inflammatory biomarkers have an effect on the risk of developing schizophrenia. Two-sample mendelian randomization study using genetic variants associated with inflammatory biomarkers as instrumental variables to improve inference. Summary association results from large consortia of candidate gene or genome-wide association studies, including several epidemiologic studies with different designs, were used. Gene-inflammatory biomarker associations were estimated in pooled samples ranging from 1645 to more than 80 000 individuals, while gene-schizophrenia associations were estimated in more than 30 000 cases and more than 45 000 ancestry-matched controls. In most studies included in the consortia, participants were of European ancestry, and the prevalence of men was approximately 50%. All studies were conducted in adults, with a wide age range (18 to 80 years). Genetically elevated circulating levels of C-reactive protein (CRP), interleukin-1 receptor antagonist (IL-1Ra), and soluble interleukin-6 receptor (sIL-6R). Risk of developing schizophrenia. Individuals with schizophrenia or schizoaffective disorders were included as cases. Given that many studies contributed to the analyses, different diagnostic procedures were used. The pooled odds ratio estimate using 18 CRP genetic instruments was 0.90 (random effects 95% CI, 0.84-0.97; P = .005) per 2-fold increment in CRP levels; consistent results were obtained using different mendelian randomization methods and a more conservative set of instruments. The odds ratio for sIL-6R was 1.06 (95% CI, 1.01-1.12; P = .02

  4. Towards an optimal sampling strategy for assessing genetic variation within and among white clover (Trifolium repens L. cultivars using AFLP

    Directory of Open Access Journals (Sweden)

    Khosro Mehdi Khanlou

    2011-01-01

    Full Text Available Cost reduction in plant breeding and conservation programs depends largely on correctly defining the minimal sample size required for the trustworthy assessment of intra- and inter-cultivar genetic variation. White clover, an important pasture legume, was chosen for studying this aspect. In clonal plants, such as the aforementioned, an appropriate sampling scheme eliminates the redundant analysis of identical genotypes. The aim was to define an optimal sampling strategy, i.e., the minimum sample size and appropriate sampling scheme for white clover cultivars, by using AFLP data (283 loci from three popular types. A grid-based sampling scheme, with an interplant distance of at least 40 cm, was sufficient to avoid any excess in replicates. Simulations revealed that the number of samples substantially influenced genetic diversity parameters. When using less than 15 per cultivar, the expected heterozygosity (He and Shannon diversity index (I were greatly underestimated, whereas with 20, more than 95% of total intra-cultivar genetic variation was covered. Based on AMOVA, a 20-cultivar sample was apparently sufficient to accurately quantify individual genetic structuring. The recommended sampling strategy facilitates the efficient characterization of diversity in white clover, for both conservation and exploitation.

  5. Validation of the 2008 Landsat Burned Area Ecv Product for North America Using Stratified Random Sampling

    Science.gov (United States)

    Brunner, N. M.; Mladinich, C. S.; Caldwell, M. K.; Beal, Y. J. G.

    2014-12-01

    The U.S. Geological Survey is generating a suite of Essential Climate Variables (ECVs) products, as defined by the Global Climate Observing System, from the Landsat data archive. Validation protocols for these products are being established, incorporating the Committee on Earth Observing Satellites Land Product Validation Subgroup's best practice guidelines and validation hierarchy stages. The sampling design and accuracy measures follow the methodology developed by the European Space Agency's Climate Change Initiative Fire Disturbance (fire_cci) project (Padilla and others, 2014). A rigorous validation was performed on the 2008 Burned Area ECV (BAECV) prototype product, using a stratified random sample of 48 Thiessen scene areas overlaying Landsat path/rows distributed across several terrestrial biomes throughout North America. The validation reference data consisted of fourteen sample sites acquired from the fire_cci project and the remaining new samples sites generated from a densification of the stratified sampling for North America. The reference burned area polygons were generated using the ABAMS (Automatic Burned Area Mapping) software (Bastarrika and others, 2011; Izagirre, 2014). Accuracy results will be presented indicating strengths and weaknesses of the BAECV algorithm.Bastarrika, A., Chuvieco, E., and Martín, M.P., 2011, Mapping burned areas from Landsat TM/ETM+ data with a two-phase algorithm: Balancing omission and commission errors: Remote Sensing of Environment, v. 115, no. 4, p. 1003-1012.Izagirre, A.B., 2014, Automatic Burned Area Mapping Software (ABAMS), Preliminary Documentation, Version 10 v4,: Vitoria-Gasteiz, Spain, University of Basque Country, p. 27.Padilla, M., Chuvieco, E., Hantson, S., Theis, R., and Sandow, C., 2014, D2.1 - Product Validation Plan: UAH - University of Alcalá de Henares (Spain), 37 p.

  6. Conic sampling: an efficient method for solving linear and quadratic programming by randomly linking constraints within the interior.

    Science.gov (United States)

    Serang, Oliver

    2012-01-01

    Linear programming (LP) problems are commonly used in analysis and resource allocation, frequently surfacing as approximations to more difficult problems. Existing approaches to LP have been dominated by a small group of methods, and randomized algorithms have not enjoyed popularity in practice. This paper introduces a novel randomized method of solving LP problems by moving along the facets and within the interior of the polytope along rays randomly sampled from the polyhedral cones defined by the bounding constraints. This conic sampling method is then applied to randomly sampled LPs, and its runtime performance is shown to compare favorably to the simplex and primal affine-scaling algorithms, especially on polytopes with certain characteristics. The conic sampling method is then adapted and applied to solve a certain quadratic program, which compute a projection onto a polytope; the proposed method is shown to outperform the proprietary software Mathematica on large, sparse QP problems constructed from mass spectometry-based proteomics.

  7. Improvement of sampling strategies for randomly distributed hotspots in soil applying a computerized simulation considering the concept of uncertainty.

    Science.gov (United States)

    Hildebrandt, Thomas; Pick, Denis; Einax, Jürgen W

    2012-02-01

    The pollution of soil and environment as a result of human activity is a major problem. Nowadays, the determination of local contaminations is of interest for environmental remediation. These hotspots can have various toxic effects on plants, animals, humans, and the whole ecological system. However, economical and juridical consequences are also possible, e.g., high costs for remediation measures. In this study three sampling strategies (simple random sampling, stratified sampling, and systematic sampling) were applied on randomly distributed hotspot contaminations to prove their efficiency in term of finding hotspots. The results were used for the validation of a computerized simulation. This application can simulate the contamination on a field, the sampling pattern, and a virtual sampling. A constant hit rate showed that none of the sampling patterns could reach better results than others. Furthermore, the uncertainty associated with the results is described by confidence intervals. It is to be considered that the uncertainty during sampling is enormous and will decrease slightly, even the number of samples applied was increased to an unreasonable amount. It is hardly possible to identify the exact number of randomly distributed hotspot contaminations by statistical sampling. But a range of possible results could be calculated. Depending on various parameters such as shape and size of the area, number of hotspots, and sample quantity, optimal sampling strategies could be derived. Furthermore, an estimation of bias arising from sampling methodology is possible. The developed computerized simulation is an innovative tool for optimizing sampling strategies in terrestrial compartments for hotspot distributions.

  8. RANdom SAmple Consensus (RANSAC) algorithm for material-informatics: application to photovoltaic solar cells.

    Science.gov (United States)

    Kaspi, Omer; Yosipof, Abraham; Senderowitz, Hanoch

    2017-06-06

    An important aspect of chemoinformatics and material-informatics is the usage of machine learning algorithms to build Quantitative Structure Activity Relationship (QSAR) models. The RANdom SAmple Consensus (RANSAC) algorithm is a predictive modeling tool widely used in the image processing field for cleaning datasets from noise. RANSAC could be used as a "one stop shop" algorithm for developing and validating QSAR models, performing outlier removal, descriptors selection, model development and predictions for test set samples using applicability domain. For "future" predictions (i.e., for samples not included in the original test set) RANSAC provides a statistical estimate for the probability of obtaining reliable predictions, i.e., predictions within a pre-defined number of standard deviations from the true values. In this work we describe the first application of RNASAC in material informatics, focusing on the analysis of solar cells. We demonstrate that for three datasets representing different metal oxide (MO) based solar cell libraries RANSAC-derived models select descriptors previously shown to correlate with key photovoltaic properties and lead to good predictive statistics for these properties. These models were subsequently used to predict the properties of virtual solar cells libraries highlighting interesting dependencies of PV properties on MO compositions.

  9. Racial variation in treatment preferences and willingness to randomize in the Spine Patient Outcomes Research Trial (SPORT).

    Science.gov (United States)

    Arega, Addisalem; Birkmeyer, Nancy J O; Lurie, Jon D N; Tosteson, Tor; Gibson, Jennifer; Taylor, Brett A; Morgan, Tamara Shawver; Weinstein, James N

    2006-09-01

    Analysis of baseline data for patients enrolled in Spine Patient Outcomes Research Trial (SPORT), a project conducting three randomized and three observational cohort studies of surgical and nonoperative treatments for intervertebral disc herniation (IDH), spinal stenosis (SpS), and degenerative spondylolisthesis (DS). To explore racial variation in treatment preferences and willingness to be randomized. Increasing minority participation in research has been a priority at the NIH. Prior studies have documented lower rates of participation in research and preferences for invasive treatment among African-Americans. Patients enrolled in SPORT (March 2000 to February 2005) that reported data on their race (n = 2,323) were classified as White (87%), Black (8%), or Other (5%). Treatment preferences (nonoperative, unsure, surgical), and willingness to be randomized were compared among these groups while controlling for baseline differences using multivariate logistic regression. RESULTS.: There were numerous significant differences in baseline characteristics among the racial groups. Following adjustment for these differences, Blacks remained less likely to prefer surgical treatment among both IDH (White, 55%; Black, 37%; Other, 55%, P = 0.023) and SpS/DS (White, 46%; Black, 30%; Other, 43%; P = 0.017) patients. Higher randomization rates among Black IDH patients (46% vs. 30%) were no longer significant following adjustment (odds ratio [OR] = 1.45, P = 0.235). Treatment preference remained a strong independent predictor of randomization in multivariate analyses for both IDH (unsure OR = 3.88, P race and willingness to be randomized.

  10. Sample size and power for a stratified doubly randomized preference design.

    Science.gov (United States)

    Cameron, Briana; Esserman, Denise A

    2016-11-21

    The two-stage (or doubly) randomized preference trial design is an important tool for researchers seeking to disentangle the role of patient treatment preference on treatment response through estimation of selection and preference effects. Up until now, these designs have been limited by their assumption of equal preference rates and effect sizes across the entire study population. We propose a stratified two-stage randomized trial design that addresses this limitation. We begin by deriving stratified test statistics for the treatment, preference, and selection effects. Next, we develop a sample size formula for the number of patients required to detect each effect. The properties of the model and the efficiency of the design are established using a series of simulation studies. We demonstrate the applicability of the design using a study of Hepatitis C treatment modality, specialty clinic versus mobile medical clinic. In this example, a stratified preference design (stratified by alcohol/drug use) may more closely capture the true distribution of patient preferences and allow for a more efficient design than a design which ignores these differences (unstratified version). © The Author(s) 2016.

  11. Notes on interval estimation of the generalized odds ratio under stratified random sampling.

    Science.gov (United States)

    Lui, Kung-Jong; Chang, Kuang-Chao

    2013-05-01

    It is not rare to encounter the patient response on the ordinal scale in a randomized clinical trial (RCT). Under the assumption that the generalized odds ratio (GOR) is homogeneous across strata, we consider four asymptotic interval estimators for the GOR under stratified random sampling. These include the interval estimator using the weighted-least-squares (WLS) approach with the logarithmic transformation (WLSL), the interval estimator using the Mantel-Haenszel (MH) type of estimator with the logarithmic transformation (MHL), the interval estimator using Fieller's theorem with the MH weights (FTMH) and the interval estimator using Fieller's theorem with the WLS weights (FTWLS). We employ Monte Carlo simulation to evaluate the performance of these interval estimators by calculating the coverage probability and the average length. To study the bias of these interval estimators, we also calculate and compare the noncoverage probabilities in the two tails of the resulting confidence intervals. We find that WLSL and MHL can generally perform well, while FTMH and FTWLS can lose either precision or accuracy. We further find that MHL is likely the least biased. Finally, we use the data taken from a study of smoking status and breathing test among workers in certain industrial plants in Houston, Texas, during 1974 to 1975 to illustrate the use of these interval estimators.

  12. Polymorphic variation in CHAT gene modulates general cognitive ability: An association study with random student cohort.

    Science.gov (United States)

    Liu, Xu; Shi, Yuanyu; Niu, Binbin; Shi, Zhangyan; Li, Junlin; Ma, Zhe; Wang, Jian; Gong, Pingyuan; Zheng, Anyun; Zhang, Fuchang; Gao, Xiaocai; Zhang, Kejin

    2016-03-23

    The choline O-acetyltransferase (CHAT) gene has been associated with various human disorders that involve cognitive impairment or deficiency. However, the influence of disease-associated variants of CHAT on normal individuals remains dubious. Here we demonstrated the impact of CHAT sequence variants (G-120A) on general human cognitive ability in a cohort of 750 Chinese undergraduate students. A multiple choice questionnaire was used to obtain basic demographic information, such as parents' occupations and education levels. We also administered and scored the Raven's Standard Progressive Matrices (RSPM). A one-way analysis of variance (ANOVA) and Kruskal-Wallis test (K-W) revealed a significant association between sequence polymorphisms of G-120A and individuals' Raven score (p=0.031 for ANOVA and p=0.026 for K-W tests). Moreover, further hierarchical analysis showed a similar trend in the association between G-120A variants and Raven scores only in the female subjects (p=0.008 for ANOVA and p=0.024 for K-W tests) but not in the male subjects. The results of a multiple linear regression confirmed that after we controlled gender, age, birthplace and other non-genetic factors, CHAT G-120A polymorphisms still significantly influenced individual Raven scores (B=-0.70, SE=0.28, t=-2.50, p=0.013). Our results demonstrated that sequence variants of CHAT were associated with human cognitive ability in not only patients with psychiatric disorders but also normal healthy individuals. However, some issues remained indeterminable, such as gender differences and the extent of the influence on individuals' general cognitive abilities; thus, the further research using an independent random sample was required. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. Control capacity and a random sampling method in exploring controllability of complex networks.

    Science.gov (United States)

    Jia, Tao; Barabási, Albert-László

    2013-01-01

    Controlling complex systems is a fundamental challenge of network science. Recent advances indicate that control over the system can be achieved through a minimum driver node set (MDS). The existence of multiple MDS's suggests that nodes do not participate in control equally, prompting us to quantify their participations. Here we introduce control capacity quantifying the likelihood that a node is a driver node. To efficiently measure this quantity, we develop a random sampling algorithm. This algorithm not only provides a statistical estimate of the control capacity, but also bridges the gap between multiple microscopic control configurations and macroscopic properties of the network under control. We demonstrate that the possibility of being a driver node decreases with a node's in-degree and is independent of its out-degree. Given the inherent multiplicity of MDS's, our findings offer tools to explore control in various complex systems.

  14. Classification of epileptic EEG signals based on simple random sampling and sequential feature selection.

    Science.gov (United States)

    Ghayab, Hadi Ratham Al; Li, Yan; Abdulla, Shahab; Diykh, Mohammed; Wan, Xiangkui

    2016-06-01

    Electroencephalogram (EEG) signals are used broadly in the medical fields. The main applications of EEG signals are the diagnosis and treatment of diseases such as epilepsy, Alzheimer, sleep problems and so on. This paper presents a new method which extracts and selects features from multi-channel EEG signals. This research focuses on three main points. Firstly, simple random sampling (SRS) technique is used to extract features from the time domain of EEG signals. Secondly, the sequential feature selection (SFS) algorithm is applied to select the key features and to reduce the dimensionality of the data. Finally, the selected features are forwarded to a least square support vector machine (LS_SVM) classifier to classify the EEG signals. The LS_SVM classifier classified the features which are extracted and selected from the SRS and the SFS. The experimental results show that the method achieves 99.90, 99.80 and 100 % for classification accuracy, sensitivity and specificity, respectively.

  15. Randomized Controlled Trial of Attention Bias Modification in a Racially Diverse, Socially Anxious, Alcohol Dependent Sample

    Science.gov (United States)

    Clerkin, Elise M.; Magee, Joshua C.; Wells, Tony T.; Beard, Courtney; Barnett, Nancy P.

    2016-01-01

    Objective Attention biases may be an important treatment target for both alcohol dependence and social anxiety. This is the first ABM trial to investigate two (vs. one) targets of attention bias within a sample with co-occurring symptoms of social anxiety and alcohol dependence. Additionally, we used trial-level bias scores (TL-BS) to capture the phenomena of attention bias in a more ecologically valid, dynamic way compared to traditional attention bias scores. Method Adult participants (N=86; 41% Female; 52% African American; 40% White) with elevated social anxiety symptoms and alcohol dependence were randomly assigned to an 8-session training condition in this 2 (Social Anxiety ABM vs. Social Anxiety Control) by 2 (Alcohol ABM vs. Alcohol Control) design. Symptoms of social anxiety, alcohol dependence, and attention bias were assessed across time. Results Multilevel models estimated the trajectories for each measure within individuals, and tested whether these trajectories differed according to the randomized training conditions. Across time, there were significant or trending decreases in all attention TL-BS parameters (but not traditional attention bias scores) and most symptom measures. However, there were not significant differences in the trajectories of change between any ABM and control conditions for any symptom measures. Conclusions These findings add to previous evidence questioning the robustness of ABM and point to the need to extend the effects of ABM to samples that are racially diverse and/or have co-occurring psychopathology. The results also illustrate the potential importance of calculating trial-level attention bias scores rather than only including traditional bias scores. PMID:27591918

  16. Random sampling or geostatistical modelling? Choosing between design-based and model-based sampling strategies for soil (with discussion)

    NARCIS (Netherlands)

    Brus, D.J.; Gruijter, de J.J.

    1997-01-01

    Classical sampling theory has been repeatedly identified with classical statistics which assumes that data are identically and independently distributed. This explains the switch of many soil scientists from design-based sampling strategies, based on classical sampling theory, to the model-based

  17. Effect of tidal volume, sampling duration, and cardiac contractility on pulse pressure and stroke volume variation during positive-pressure ventilation.

    Science.gov (United States)

    Kim, Hyung Kook; Pinsky, Michael R

    2008-10-01

    Both pulse pressure variation and stroke volume variation during intermittent positive-pressure ventilation predict preload responsiveness. However, because ventilatory and cardiac frequencies are not the same, increasing the number of breaths sampled may increase calculated pulse pressure variation and stroke volume variation because larger (max) and smaller (min) pulse pressure and stroke volume may occur. Tidal volume and contractility may also alter pulse pressure variation and stroke volume variation. We hypothesized that the magnitude of pulse pressure variation would increase with sampling duration, and that both tidal volume and contractility would independently alter pulse pressure variation and stroke volume variation. In seven pentobarbital-anesthetized intact dogs arterial and left ventricular pressure (Millar) and left ventricular volume (Leycom) were measured over 8 intermittent positive-pressure ventilation breaths at tidal volume of 5, 10, 15, and 20 mL/kg (f = 20/min, 40% inspiratory time) under baseline, esmolol (2 mg/min), dobutamine infusions (5 microg/kg/min) and following volume loading (500 mL NaCl). Stroke volume variation was calculated using pulse contour method (PiCCO, Pulsion Medical Systems, Munich, Germany) averaged over 12 secs. Pulse pressure variation was calculated as 100 x (PPmax - PPmin)/PPmean and calculated over 1, 2, 3, 4, 5, 6, 7, or 8 breaths. Pulse pressure variation increased progressively with increasing sampling duration up to but not exceeding five breaths. The effect on sampling duration was increased by greater tidal volume. Esmolol infusion decreased both pulse pressure variation and stroke volume variation as compared with baseline (p variation or stroke volume variation. Sampling duration, tidal volume, and beta-adrenergic blockade differentially alters pulse pressure variation and stroke volume variation during intermittent positive-pressure ventilation. Thus, separate validation is required to define threshold

  18. Random Photon Absorption Model Elucidates How Early Gain Control in Fly Photoreceptors Arises from Quantal Sampling

    Science.gov (United States)

    Song, Zhuoyi; Zhou, Yu; Juusola, Mikko

    2016-01-01

    Many diurnal photoreceptors encode vast real-world light changes effectively, but how this performance originates from photon sampling is unclear. A 4-module biophysically-realistic fly photoreceptor model, in which information capture is limited by the number of its sampling units (microvilli) and their photon-hit recovery time (refractoriness), can accurately simulate real recordings and their information content. However, sublinear summation in quantum bump production (quantum-gain-nonlinearity) may also cause adaptation by reducing the bump/photon gain when multiple photons hit the same microvillus simultaneously. Here, we use a Random Photon Absorption Model (RandPAM), which is the 1st module of the 4-module fly photoreceptor model, to quantify the contribution of quantum-gain-nonlinearity in light adaptation. We show how quantum-gain-nonlinearity already results from photon sampling alone. In the extreme case, when two or more simultaneous photon-hits reduce to a single sublinear value, quantum-gain-nonlinearity is preset before the phototransduction reactions adapt the quantum bump waveform. However, the contribution of quantum-gain-nonlinearity in light adaptation depends upon the likelihood of multi-photon-hits, which is strictly determined by the number of microvilli and light intensity. Specifically, its contribution to light-adaptation is marginal (≤ 1%) in fly photoreceptors with many thousands of microvilli, because the probability of simultaneous multi-photon-hits on any one microvillus is low even during daylight conditions. However, in cells with fewer sampling units, the impact of quantum-gain-nonlinearity increases with brightening light. PMID:27445779

  19. Gardner's Two Children Problems and Variations: Puzzles with Conditional Probability and Sample Spaces

    Science.gov (United States)

    Taylor, Wendy; Stacey, Kaye

    2014-01-01

    This article presents "The Two Children Problem," published by Martin Gardner, who wrote a famous and widely-read math puzzle column in the magazine "Scientific American," and a problem presented by puzzler Gary Foshee. This paper explains the paradox of Problems 2 and 3 and many other variations of the theme. Then the authors…

  20. Notes on interval estimation of the gamma correlation under stratified random sampling.

    Science.gov (United States)

    Lui, Kung-Jong; Chang, Kuang-Chao

    2012-07-01

    We have developed four asymptotic interval estimators in closed forms for the gamma correlation under stratified random sampling, including the confidence interval based on the most commonly used weighted-least-squares (WLS) approach (CIWLS), the confidence interval calculated from the Mantel-Haenszel (MH) type estimator with the Fisher-type transformation (CIMHT), the confidence interval using the fundamental idea of Fieller's Theorem (CIFT) and the confidence interval derived from a monotonic function of the WLS estimator of Agresti's α with the logarithmic transformation (MWLSLR). To evaluate the finite-sample performance of these four interval estimators and note the possible loss of accuracy in application of both Wald's confidence interval and MWLSLR using pooled data without accounting for stratification, we employ Monte Carlo simulation. We use the data taken from a general social survey studying the association between the income level and job satisfaction with strata formed by genders in black Americans published elsewhere to illustrate the practical use of these interval estimators. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Predictive value of testing random urine sample to detect microalbuminuria in diabetic subjects during outpatient visit.

    Science.gov (United States)

    Bouhanick, B; Berrut, G; Chameau, A M; Hallar, M; Bled, F; Chevet, B; Vergely, J; Rohmer, V; Fressinaud, P; Marre, M

    1992-01-01

    The predictive value of random urine sample during outpatient visit to predict persistent microalbuminuria was studied in 76 Type 1, insulin-dependent diabetic subjects, 61 Type 2, non-insulin-dependent diabetic subjects, and 72 Type 2, insulin-treated diabetic subjects. Seventy-six patients attended outpatient clinic during morning, and 133 during afternoon. Microalbuminuria was suspected if Urinary Albumin Excretion (UAE) exceeded 20 mg/l. All patients were hospitalized within 6 months following outpatient visit, and persistent microalbuminuria was assessed then if UAE was between 30 and 300 mg/24 h on 2-3 occasions in 3 urines samples. Of these 209 subjects eighty-three were also screened with Microbumintest (Ames-Bayer), a semi-quantitative method. Among the 209 subjects, 71 were positive both for microalbuminuria during outpatient visit and a persistent microalbuminuria during hospitalization: sensitivity 91.0%, specificity 83.2%, concordance 86.1%, and positive predictive value 76.3% (chi-squared test: 191; p less than 10(-4)). Data were not different for subjects examined on morning, or on afternoon. Among the 83 subjects also screened with Microbumintest, 22 displayed both a positive reaction and a persistent microalbuminuria: sensitivity 76%, specificity 81%, concordance 80%, and positive predictive value 69% (chi-squared test: 126; p less than 10(-4)). Both types of screening appeared equally effective during outpatient visit. Hence, a persistent microalbuminuria can be predicted during an outpatient visit in a diabetic clinic.

  2. Effectiveness of hand hygiene education among a random sample of women from the community.

    Science.gov (United States)

    Ubheeram, J; Biranjia-Hurdoyal, S D

    2017-03-01

    The effectiveness of hand hygiene education was investigated by studying the hand hygiene awareness and bacterial hand contamination among a random sample of 170 women in the community. Questionnaire was used to assess the hand hygiene awareness score, followed by swabbing of the dominant hand. Bacterial identification was done by conventional biochemical tests. Better hand hygiene awareness score was significantly associated with age, scarce bacterial growth and absence of potential pathogen (p hand samples, bacterial growth was noted in 155 (91.2%), which included 91 (53.5%) heavy growth, 53 (31.2%) moderate growth and 11 (6.47%) scanty growth. The presence of enteric bacteria was associated with long nails (49.4% vs 29.2%; p = 0.007; OR = 2.3; 95% CI: 1.25-4.44) while finger rings were associated with higher bacterial load (p = 0.003). Coliforms was significantly higher among women who had a lower hand hygiene awareness score, washed their hands at lower frequency (59.0% vs 32.8%; p = 0.003; OR = 2.9; 95% CI: 1.41-6.13) and used common soap as compared to antiseptic soaps (69.7% vs 30.3%, p = 0.000; OR = 4.11; 95% CI: 1.67-10.12). Level of hand hygiene awareness among the participants was satisfactory but not the compliance of hand washing practice, especially among the elders.

  3. Association between stalking victimisation and psychiatric morbidity in a random community sample.

    Science.gov (United States)

    Purcell, Rosemary; Pathé, Michele; Mullen, Paul E

    2005-11-01

    No studies have assessed psychopathology among victims of stalking who have not sought specialist help. To examine the associations between stalking victimisation and psychiatric morbidity in a representative community sample. A random community sample (n=1844) completed surveys examining the experience of harassment and current mental health. The 28-item General Health Questionnaire (GHQ-28) and the Impact of Event Scale were used to assess symptomatology in those reporting brief harassment (n=196) or protracted stalking (n=236) and a matched control group reporting no harassment (n=432). Rates of caseness on the GHQ-28 were higher among stalking victims (36.4%) than among controls (19.3%) and victims of brief harassment (21.9%). Psychiatric morbidity did not differ according to the recency of victimisation, with 34.1% of victims meeting caseness criteria 1 year after stalking had ended. In a significant minority of victims, stalking victimisation is associated with psychiatric morbidity that may persist long after it has ceased. Recognition of the immediate and long-term impacts of stalking is necessary to assist victims and help alleviate distress and long-term disability.

  4. Random sample community-based health surveys: does the effort to reach participants matter?

    Science.gov (United States)

    Messiah, Antoine; Castro, Grettel; Rodríguez de la Vega, Pura; Acuna, Juan M

    2014-12-15

    Conducting health surveys with community-based random samples are essential to capture an otherwise unreachable population, but these surveys can be biased if the effort to reach participants is insufficient. This study determines the desirable amount of effort to minimise such bias. A household-based health survey with random sampling and face-to-face interviews. Up to 11 visits, organised by canvassing rounds, were made to obtain an interview. Single-family homes in an underserved and understudied population in North Miami-Dade County, Florida, USA. Of a probabilistic sample of 2200 household addresses, 30 corresponded to empty lots, 74 were abandoned houses, 625 households declined to participate and 265 could not be reached and interviewed within 11 attempts. Analyses were performed on the 1206 remaining households. Each household was asked if any of their members had been told by a doctor that they had high blood pressure, heart disease including heart attack, cancer, diabetes, anxiety/ depression, obesity or asthma. Responses to these questions were analysed by the number of visit attempts needed to obtain the interview. Return per visit fell below 10% after four attempts, below 5% after six attempts and below 2% after eight attempts. As the effort increased, household size decreased, while household income and the percentage of interviewees active and employed increased; proportion of the seven health conditions decreased, four of which did so significantly: heart disease 20.4-9.2%, high blood pressure 63.5-58.1%, anxiety/depression 24.4-9.2% and obesity 21.8-12.6%. Beyond the fifth attempt, however, cumulative percentages varied by less than 1% and precision varied by less than 0.1%. In spite of the early and steep drop, sustaining at least five attempts to reach participants is necessary to reduce selection bias. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

  5. Total variation regularization of the 3-D gravity inverse problem using a randomized generalized singular value decomposition

    Science.gov (United States)

    Vatankhah, Saeed; Renaut, Rosemary A.; Ardestani, Vahid E.

    2018-01-01

    We present a fast algorithm for the total variation regularization of the 3-D gravity inverse problem. Through imposition of the total variation regularization, subsurface structures presenting with sharp discontinuities are preserved better than when using a conventional minimum-structure inversion. The associated problem formulation for the regularization is non linear but can be solved using an iteratively reweighted least squares algorithm. For small scale problems the regularized least squares problem at each iteration can be solved using the generalized singular value decomposition. This is not feasible for large, or even moderate, scale problems. Instead we introduce the use of a randomized generalized singular value decomposition in order to reduce the dimensions of the problem and provide an effective and efficient solution technique. For further efficiency an alternating direction algorithm is used to implement the total variation weighting operator within the iteratively reweighted least squares algorithm. Presented results for synthetic examples demonstrate that the novel randomized decomposition provides good accuracy for reduced computational and memory demands as compared to use of classical approaches.

  6. An information theory approach for evaluating earth radiation budget (ERB) measurements - Nonuniform sampling of diurnal longwave flux variations

    Science.gov (United States)

    Halyo, Nesim; Direskeneli, Haldun; Barkstrom, Bruce R.

    1991-01-01

    Satellite measurements are subject to a wide range of uncertainties due to their temporal, spatial, and directional sampling characteristics. An information-theory approach is suggested to examine the nonuniform temporal sampling of ERB measurements. The information (i.e., its entropy or uncertainty) before and after the measurements is determined, and information gain (IG) is defined as a reduction in the uncertainties involved. A stochastic model for the diurnal outgoing flux variations that affect the ERB is developed. Using Gaussian distributions for the a priori and measured radiant exitance fields, the IG is obtained by computing the a posteriori covariance. The IG for the monthly outgoing flux measurements is examined for different orbital parameters and orbital tracks, using the Earth Observing System orbital parameters as specific examples. Variations in IG due to changes in the orbit's inclination angle and the initial ascending node local time are investigated.

  7. Sources of pre-analytical variations in yield of DNA extracted from blood samples: analysis of 50,000 DNA samples in EPIC.

    Directory of Open Access Journals (Sweden)

    Elodie Caboux

    Full Text Available The European Prospective Investigation into Cancer and nutrition (EPIC is a long-term, multi-centric prospective study in Europe investigating the relationships between cancer and nutrition. This study has served as a basis for a number of Genome-Wide Association Studies (GWAS and other types of genetic analyses. Over a period of 5 years, 52,256 EPIC DNA samples have been extracted using an automated DNA extraction platform. Here we have evaluated the pre-analytical factors affecting DNA yield, including anthropometric, epidemiological and technical factors such as center of subject recruitment, age, gender, body-mass index, disease case or control status, tobacco consumption, number of aliquots of buffy coat used for DNA extraction, extraction machine or procedure, DNA quantification method, degree of haemolysis and variations in the timing of sample processing. We show that the largest significant variations in DNA yield were observed with degree of haemolysis and with center of subject recruitment. Age, gender, body-mass index, cancer case or control status and tobacco consumption also significantly impacted DNA yield. Feedback from laboratories which have analyzed DNA with different SNP genotyping technologies demonstrate that the vast majority of samples (approximately 88% performed adequately in different types of assays. To our knowledge this study is the largest to date to evaluate the sources of pre-analytical variations in DNA extracted from peripheral leucocytes. The results provide a strong evidence-based rationale for standardized recommendations on blood collection and processing protocols for large-scale genetic studies.

  8. Different landslide sampling strategies in a grid-based bi-variate statistical susceptibility model

    Science.gov (United States)

    Hussin, Haydar Y.; Zumpano, Veronica; Reichenbach, Paola; Sterlacchini, Simone; Micu, Mihai; van Westen, Cees; Bălteanu, Dan

    2016-01-01

    This study had three aims. The first was to assess the performance of the weights-of-evidence (WofE) landslide susceptibility model in areas that are very different in terms of size, geoenvironmental settings, and landslide types. The second was to test the appropriate strategies to sample the mapped landslide polygon. The final aim was to evaluate the performance of the method to changes in the landslide sample size used to train the model. The method was applied to two areas: the Fella River basin (eastern Italian Alps) containing debris flows, and Buzau County (Romanian Carpathians) with shallow landslides. The three landslide sampling strategies used were: (1) the landslide scarp centroid, (2) points populating the scarp on a 50-m grid, and (3) the entire scarp polygon. The highest success rates were obtained when sampling shallow landslides as 50-m grid-points and debris flow scarps as polygons. Prediction rates were highest when using the entire scarp polygon method for both landslide types. The sample size test using the landslide centroids showed that a sample of 104 debris flow scarps was sufficient to predict the remaining 941 debris flows in the Fella River basin, while 161 shallow landslides was the minimum required number to predict the remaining 1451 scarps in Buzau County. Below these landslide sample thresholds, model performance was too low. However, using more landslides than the threshold produced a plateau effect with little to no increase in the model performance rates.

  9. Sample-to-sample fluctuations of power spectrum of a random motion in a periodic Sinai model

    Science.gov (United States)

    Dean, David S.; Iorio, Antonio; Marinari, Enzo; Oshanin, Gleb

    2016-09-01

    The Sinai model of a tracer diffusing in a quenched Brownian potential is a much-studied problem exhibiting a logarithmically slow anomalous diffusion due to the growth of energy barriers with the system size. However, if the potential is random but periodic, the regime of anomalous diffusion crosses over to one of normal diffusion once a tracer has diffused over a few periods of the system. Here we consider a system in which the potential is given by a Brownian bridge on a finite interval (0 ,L ) and then periodically repeated over the whole real line and study the power spectrum S (f ) of the diffusive process x (t ) in such a potential. We show that for most of realizations of x (t ) in a given realization of the potential, the low-frequency behavior is S (f ) ˜A /f2 , i.e., the same as for standard Brownian motion, and the amplitude A is a disorder-dependent random variable with a finite support. Focusing on the statistical properties of this random variable, we determine the moments of A of arbitrary, negative, or positive order k and demonstrate that they exhibit a multifractal dependence on k and a rather unusual dependence on the temperature and on the periodicity L , which are supported by atypical realizations of the periodic disorder. We finally show that the distribution of A has a log-normal left tail and exhibits an essential singularity close to the right edge of the support, which is related to the Lifshitz singularity. Our findings are based both on analytic results and on extensive numerical simulations of the process x (t ) .

  10. Towards monitoring biodiversity in Amazonian forests: how regular samples capture meso-scale altitudinal variation in 25 km2 plots.

    Directory of Open Access Journals (Sweden)

    Darren Norris

    Full Text Available Ecological monitoring and sampling optima are context and location specific. Novel applications (e.g. biodiversity monitoring for environmental service payments call for renewed efforts to establish reliable and robust monitoring in biodiversity rich areas. As there is little information on the distribution of biodiversity across the Amazon basin, we used altitude as a proxy for biological variables to test whether meso-scale variation can be adequately represented by different sample sizes in a standardized, regular-coverage sampling arrangement.We used Shuttle-Radar-Topography-Mission digital elevation values to evaluate if the regular sampling arrangement in standard RAPELD (rapid assessments ("RAP" over the long-term (LTER ["PELD" in Portuguese] grids captured patters in meso-scale spatial variation. The adequacy of different sample sizes (n = 4 to 120 were examined within 32,325 km2/3,232,500 ha (1293×25 km2 sample areas distributed across the legal Brazilian Amazon. Kolmogorov-Smirnov-tests, correlation and root-mean-square-error were used to measure sample representativeness, similarity and accuracy respectively. Trends and thresholds of these responses in relation to sample size and standard-deviation were modeled using Generalized-Additive-Models and conditional-inference-trees respectively. We found that a regular arrangement of 30 samples captured the distribution of altitude values within these areas. Sample size was more important than sample standard deviation for representativeness and similarity. In contrast, accuracy was more strongly influenced by sample standard deviation. Additionally, analysis of spatially interpolated data showed that spatial patterns in altitude were also recovered within areas using a regular arrangement of 30 samples.Our findings show that the logistically feasible sample used in the RAPELD system successfully recovers meso-scale altitudinal patterns. This suggests that the sample size and regular

  11. Engineering practice variation through provider agreement: a cluster-randomized feasibility trial

    OpenAIRE

    McCarren M; Twedt EL; Mansuri FM; Nelson PR; Peek BT

    2014-01-01

    Madeline McCarren,1 Elaine L Twedt,1 Faizmohamed M Mansuri,2 Philip R Nelson,3 Brian T Peek3 1Pharmacy Benefits Management Services, Department of Veterans Affairs, Hines, IL, 2Wilkes-Barre VA Medical Center, Wilkes-Barre, PA, 3Charles George VA Medical Center, Asheville, NC, USA Purpose: Minimal-risk randomized trials that can be embedded in practice could facilitate learning health-care systems. A cluster-randomized design was proposed to compare treatment strategies by assigning clusters...

  12. Influence of common preanalytical variations on the metabolic profile of serum samples in biobanks

    Energy Technology Data Exchange (ETDEWEB)

    Fliniaux, Ophelie [University of Picardie Jules Verne, Laboratoire de Phytotechnologie EA 3900-BioPI (France); Gaillard, Gwenaelle [Biobanque de Picardie (France); Lion, Antoine [University of Picardie Jules Verne, Laboratoire de Phytotechnologie EA 3900-BioPI (France); Cailleu, Dominique [Batiment Serres-Transfert, rue de Mai/rue Dallery, Plateforme Analytique (France); Mesnard, Francois, E-mail: francois.mesnard@u-picardie.fr [University of Picardie Jules Verne, Laboratoire de Phytotechnologie EA 3900-BioPI (France); Betsou, Fotini [Integrated Biobank of Luxembourg (Luxembourg)

    2011-12-15

    A blood pre-centrifugation delay of 24 h at room temperature influenced the proton NMR spectroscopic profiles of human serum. A blood pre-centrifugation delay of 24 h at 4 Degree-Sign C did not influence the spectroscopic profile as compared with 4 h delays at either room temperature or 4 Degree-Sign C. Five or ten serum freeze-thaw cycles also influenced the proton NMR spectroscopic profiles. Certain common in vitro preanalytical variations occurring in biobanks may impact the metabolic profile of human serum.

  13. The international Genome sample resource (IGSR): A worldwide collection of genome variation incorporating the 1000 Genomes Project data

    Science.gov (United States)

    Clarke, Laura; Fairley, Susan; Zheng-Bradley, Xiangqun; Streeter, Ian; Perry, Emily; Lowy, Ernesto; Tassé, Anne-Marie; Flicek, Paul

    2017-01-01

    The International Genome Sample Resource (IGSR; http://www.internationalgenome.org) expands in data type and population diversity the resources from the 1000 Genomes Project. IGSR represents the largest open collection of human variation data and provides easy access to these resources. IGSR was established in 2015 to maintain and extend the 1000 Genomes Project data, which has been widely used as a reference set of human variation and by researchers developing analysis methods. IGSR has mapped all of the 1000 Genomes sequence to the newest human reference (GRCh38), and will release updated variant calls to ensure maximal usefulness of the existing data. IGSR is collecting new structural variation data on the 1000 Genomes samples from long read sequencing and other technologies, and will collect relevant functional data into a single comprehensive resource. IGSR is extending coverage with new populations sequenced by collaborating groups. Here, we present the new data and analysis that IGSR has made available. We have also introduced a new data portal that increases discoverability of our data—previously only browseable through our FTP site—by focusing on particular samples, populations or data sets of interest. PMID:27638885

  14. Multivariate analysis of reflectance spectra from propolis: geographical variation in Romanian samples.

    Science.gov (United States)

    Moţ, Augustin Cătălin; Soponar, Florin; Sârbu, Costel

    2010-05-15

    The present study described reflectance spectroscopy as a suitable analytical tool to discriminate the floral origin of 39 Romanian propolis samples. Relevant differences between the UV-vis reflectance spectra of the investigated propolis samples within the 220-850nm spectral range were found. The results obtained applying cluster analysis, principal component analysis and linear discriminant analysis to the digitized data of zero order, zero order normalized and first order derivative spectra support the reliability of this technique. In addition, the application of the linear discriminant analysis to the score matrices corresponding to the first principal components appeared to be an illuminating solution. Generally, the samples have been assigned to two large groups in a good agreement with their vegetal sampling location, samples originating from predominant forest area and samples originating from meadows. Within the first group, two subgroups were identified according to the dominant type of the forest, deciduous or resinous, while within the last group three subgroups were found according to the extend and variety of the meadow.

  15. Random Model Sampling: Making Craig Interpolation Work When It Should Not

    Directory of Open Access Journals (Sweden)

    Marat Akhin

    2014-01-01

    Full Text Available One of the most serious problems when doing program analyses is dealing with function calls. While function inlining is the traditional approach to this problem, it nonetheless suffers from the increase in analysis complexity due to the state space explosion. Craig interpolation has been successfully used in recent years in the context of bounded model checking to do function summarization which allows one to replace the complete function body with its succinct summary and, therefore, reduce the complexity. Unfortunately this technique can be applied only to a pair of unsatisfiable formulae.In this work-in-progress paper we present an approach to function summarization based on Craig interpolation that overcomes its limitation by using random model sampling. It captures interesting input/output relations, strengthening satisfiable formulae into unsatisfiable ones and thus allowing the use of Craig interpolation. Preliminary experiments show the applicability of this approach; in our future work we plan to do a full evaluation on real-world examples.

  16. Discriminative motif discovery via simulated evolution and random under-sampling.

    Directory of Open Access Journals (Sweden)

    Tao Song

    Full Text Available Conserved motifs in biological sequences are closely related to their structure and functions. Recently, discriminative motif discovery methods have attracted more and more attention. However, little attention has been devoted to the data imbalance problem, which is one of the main reasons affecting the performance of the discriminative models. In this article, a simulated evolution method is applied to solve the multi-class imbalance problem at the stage of data preprocessing, and at the stage of Hidden Markov Models (HMMs training, a random under-sampling method is introduced for the imbalance between the positive and negative datasets. It is shown that, in the task of discovering targeting motifs of nine subcellular compartments, the motifs found by our method are more conserved than the methods without considering data imbalance problem and recover the most known targeting motifs from Minimotif Miner and InterPro. Meanwhile, we use the found motifs to predict protein subcellular localization and achieve higher prediction precision and recall for the minority classes.

  17. Neurofeedback Against Binge Eating: A Randomized Controlled Trial in a Female Subclinical Threshold Sample.

    Science.gov (United States)

    Schmidt, Jennifer; Martin, Alexandra

    2016-09-01

    Brain-directed treatment techniques, such as neurofeedback, have recently been proposed as adjuncts in the treatment of eating disorders to improve therapeutic outcomes. In line with this recommendation, a cue exposure EEG-neurofeedback protocol was developed. The present study aimed at the evaluation of the specific efficacy of neurofeedback to reduce subjective binge eating in a female subthreshold sample. A total of 75 subjects were randomized to EEG-neurofeedback, mental imagery with a comparable treatment set-up or a waitlist group. At post-treatment, only EEG-neurofeedback led to a reduced frequency of binge eating (p = .015, g = 0.65). The effects remained stable to a 3-month follow-up. EEG-neurofeedback further showed particular beneficial effects on perceived stress and dietary self-efficacy. Differences in outcomes did not arise from divergent treatment expectations. Because EEG-neurofeedback showed a specific efficacy, it may be a promising brain-directed approach that should be tested as a treatment adjunct in clinical groups with binge eating. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association. Copyright © 2016 John Wiley & Sons, Ltd and Eating Disorders Association.

  18. A coupled well-balanced and random sampling scheme for computing bubble oscillations*

    Directory of Open Access Journals (Sweden)

    Jung Jonathan

    2012-04-01

    Full Text Available We propose a finite volume scheme to study the oscillations of a spherical bubble of gas in a liquid phase. Spherical symmetry implies a geometric source term in the Euler equations. Our scheme satisfies the well-balanced property. It is based on the VFRoe approach. In order to avoid spurious pressure oscillations, the well-balanced approach is coupled with an ALE (Arbitrary Lagrangian Eulerian technique at the interface and a random sampling remap. Nous proposons un schéma de volumes finis pour étudier les oscillations d’une bulle sphérique de gaz dans l’eau. La symétrie sphérique fait apparaitre un terme source géométrique dans les équations d’Euler. Notre schéma est basé sur une approche VFRoe et préserve les états stationnaires. Pour éviter les oscillations de pression, l’approche well-balanced est couplée avec une approche ALE (Arbitrary Lagrangian Eulerian, et une étape de projection basée sur un échantillonage aléatoire.

  19. Accelerating Markov chain Monte Carlo simulation by differential evolution with self-adaptive randomized subspace sampling

    Energy Technology Data Exchange (ETDEWEB)

    Vrugt, Jasper A [Los Alamos National Laboratory; Hyman, James M [Los Alamos National Laboratory; Robinson, Bruce A [Los Alamos National Laboratory; Higdon, Dave [Los Alamos National Laboratory; Ter Braak, Cajo J F [NETHERLANDS; Diks, Cees G H [UNIV OF AMSTERDAM

    2008-01-01

    Markov chain Monte Carlo (MCMC) methods have found widespread use in many fields of study to estimate the average properties of complex systems, and for posterior inference in a Bayesian framework. Existing theory and experiments prove convergence of well constructed MCMC schemes to the appropriate limiting distribution under a variety of different conditions. In practice, however this convergence is often observed to be disturbingly slow. This is frequently caused by an inappropriate selection of the proposal distribution used to generate trial moves in the Markov Chain. Here we show that significant improvements to the efficiency of MCMC simulation can be made by using a self-adaptive Differential Evolution learning strategy within a population-based evolutionary framework. This scheme, entitled DiffeRential Evolution Adaptive Metropolis or DREAM, runs multiple different chains simultaneously for global exploration, and automatically tunes the scale and orientation of the proposal distribution in randomized subspaces during the search. Ergodicity of the algorithm is proved, and various examples involving nonlinearity, high-dimensionality, and multimodality show that DREAM is generally superior to other adaptive MCMC sampling approaches. The DREAM scheme significantly enhances the applicability of MCMC simulation to complex, multi-modal search problems.

  20. Comparing cluster-level dynamic treatment regimens using sequential, multiple assignment, randomized trials: Regression estimation and sample size considerations.

    Science.gov (United States)

    NeCamp, Timothy; Kilbourne, Amy; Almirall, Daniel

    2017-08-01

    Cluster-level dynamic treatment regimens can be used to guide sequential treatment decision-making at the cluster level in order to improve outcomes at the individual or patient-level. In a cluster-level dynamic treatment regimen, the treatment is potentially adapted and re-adapted over time based on changes in the cluster that could be impacted by prior intervention, including aggregate measures of the individuals or patients that compose it. Cluster-randomized sequential multiple assignment randomized trials can be used to answer multiple open questions preventing scientists from developing high-quality cluster-level dynamic treatment regimens. In a cluster-randomized sequential multiple assignment randomized trial, sequential randomizations occur at the cluster level and outcomes are observed at the individual level. This manuscript makes two contributions to the design and analysis of cluster-randomized sequential multiple assignment randomized trials. First, a weighted least squares regression approach is proposed for comparing the mean of a patient-level outcome between the cluster-level dynamic treatment regimens embedded in a sequential multiple assignment randomized trial. The regression approach facilitates the use of baseline covariates which is often critical in the analysis of cluster-level trials. Second, sample size calculators are derived for two common cluster-randomized sequential multiple assignment randomized trial designs for use when the primary aim is a between-dynamic treatment regimen comparison of the mean of a continuous patient-level outcome. The methods are motivated by the Adaptive Implementation of Effective Programs Trial which is, to our knowledge, the first-ever cluster-randomized sequential multiple assignment randomized trial in psychiatry.

  1. Goal-directed intraoperative fluid therapy guided by stroke volume and its variation in high-risk surgical patients : a prospective randomized multicentre study

    NARCIS (Netherlands)

    Scheeren, Thomas W. L.; Wiesenack, Christoph; Gerlach, Herwig; Marx, Gernot

    Perioperative hemodynamic optimisation improves postoperative outcome for patients undergoing high-risk surgery (HRS). In this prospective randomized multicentre study we studied the effects of an individualized, goal-directed fluid management based on continuous stroke volume variation (SVV) and

  2. Drivers and spatio-temporal extent of hyporheic patch variation: implications for sampling.

    Directory of Open Access Journals (Sweden)

    Alexander Braun

    Full Text Available The hyporheic zone in stream ecosystems is a heterogeneous key habitat for species across many taxa. Consequently, it attracts high attention among freshwater scientists, but generally applicable guidelines on sampling strategies are lacking. Thus, the objective of this study was to develop and validate such sampling guidelines. Applying geostatistical analysis, we quantified the spatio-temporal variability of parameters, which characterize the physico-chemical substratum conditions in the hyporheic zone. We investigated eight stream reaches in six small streams that are typical for the majority of temperate areas. Data was collected on two occasions in six stream reaches (development data, and once in two additional reaches, after one year (validation data. In this study, the term spatial variability refers to patch contrast (patch to patch variance and patch size (spatial extent of a patch. Patch contrast of hyporheic parameters (specific conductance, pH and dissolved oxygen increased with macrophyte cover (r(2=0.95, p<0.001, while patch size of hyporheic parameters decreased from 6 to 2 m with increasing sinuosity of the stream course (r(2=0.91, p<0.001, irrespective of the time of year. Since the spatial variability of hyporheic parameters varied between stream reaches, our results suggest that sampling design should be adapted to suit specific stream reaches. The distance between sampling sites should be inversely related to the sinuosity, while the number of samples should be related to macrophyte cover.

  3. Depression and Racial/Ethnic Variations within a Diverse Nontraditional College Sample

    Science.gov (United States)

    Hudson, Richard; Towey, James; Shinar, Ori

    2008-01-01

    The study's objective was to ascertain whether rates of depression were significantly higher for Dominican, Puerto Rican, South and Central American and Jamaican/Haitian students than for African American and White students. The sample consisted of 987 predominantly nontraditional college students. The depression rate for Dominican students was…

  4. Minimizing technical variation during sample preparation prior to label-free quantitative mass spectrometry.

    Science.gov (United States)

    Scheerlinck, E; Dhaenens, M; Van Soom, A; Peelman, L; De Sutter, P; Van Steendam, K; Deforce, D

    2015-12-01

    Sample preparation is the crucial starting point to obtain high-quality mass spectrometry data and can be divided into two main steps in a bottom-up proteomics approach: cell/tissue lysis with or without detergents and a(n) (in-solution) digest comprising denaturation, reduction, alkylation, and digesting of the proteins. Here, some important considerations, among others, are that the reagents used for sample preparation can inhibit the digestion enzyme (e.g., 0.1% sodium dodecyl sulfate [SDS] and 0.5 M guanidine HCl), give rise to ion suppression (e.g., polyethylene glycol [PEG]), be incompatible with liquid chromatography-tandem mass spectrometry (LC-MS/MS) (e.g., SDS), and can induce additional modifications (e.g., urea). Taken together, all of these irreproducible effects are gradually becoming a problem when label-free quantitation of the samples is envisioned such as during the increasingly popular high-definition mass spectrometry (HDMS(E)) and sequential window acquisition of all theoretical fragment ion spectra (SWATH) data-independent acquisition strategies. Here, we describe the detailed validation of a reproducible method with sufficient protein yield for sample preparation without any known LC-MS/MS interfering substances by using 1% sodium deoxycholate (SDC) during both cell lysis and in-solution digest. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  5. Drivers and spatio-temporal extent of hyporheic patch variation: implications for sampling.

    Science.gov (United States)

    Braun, Alexander; Auerswald, Karl; Geist, Juergen

    2012-01-01

    The hyporheic zone in stream ecosystems is a heterogeneous key habitat for species across many taxa. Consequently, it attracts high attention among freshwater scientists, but generally applicable guidelines on sampling strategies are lacking. Thus, the objective of this study was to develop and validate such sampling guidelines. Applying geostatistical analysis, we quantified the spatio-temporal variability of parameters, which characterize the physico-chemical substratum conditions in the hyporheic zone. We investigated eight stream reaches in six small streams that are typical for the majority of temperate areas. Data was collected on two occasions in six stream reaches (development data), and once in two additional reaches, after one year (validation data). In this study, the term spatial variability refers to patch contrast (patch to patch variance) and patch size (spatial extent of a patch). Patch contrast of hyporheic parameters (specific conductance, pH and dissolved oxygen) increased with macrophyte cover (r(2)=0.95, psampling design should be adapted to suit specific stream reaches. The distance between sampling sites should be inversely related to the sinuosity, while the number of samples should be related to macrophyte cover.

  6. Ethnic Variations of Pathways Linking Socioeconomic Status, Parenting, and Preacademic Skills in a Nationally Representative Sample

    Science.gov (United States)

    Iruka, Iheoma U.; Dotterer, Aryn M.; Pungello, Elizabeth P.

    2014-01-01

    Research Findings: Grounded in the investment model and informed by the integrative theory of the study of minority children, this study used the Early Childhood Longitudinal Study-Birth Cohort data set, a nationally representative sample of young children, to investigate whether the association between socioeconomic status (family income and…

  7. Falling number sampling variation within trucks at first point of sale

    Science.gov (United States)

    Falling number (FN) is a test widely performed on raw samples of wheat and barley as a means to indicate the level of enzyme activity, alpha-amylase, associated with seed germination. In most circumstances of wheat, high activity levels are associated with decreased quality of the end products, and...

  8. Seasonal and Temporal Variation in Release of Antibiotics in Hospital Wastewater: Estimation Using Continuous and Grab Sampling

    Science.gov (United States)

    Diwan, Vishal; Stålsby Lundborg, Cecilia; Tamhankar, Ashok J.

    2013-01-01

    The presence of antibiotics in the environment and their subsequent impact on resistance development has raised concerns globally. Hospitals are a major source of antibiotics released into the environment. To reduce these residues, research to improve knowledge of the dynamics of antibiotic release from hospitals is essential. Therefore, we undertook a study to estimate seasonal and temporal variation in antibiotic release from two hospitals in India over a period of two years. For this, 6 sampling sessions of 24 hours each were conducted in the three prominent seasons of India, at all wastewater outlets of the two hospitals, using continuous and grab sampling methods. An in-house wastewater sampler was designed for continuous sampling. Eight antibiotics from four major antibiotic groups were selected for the study. To understand the temporal pattern of antibiotic release, each of the 24-hour sessions were divided in three sub-sampling sessions of 8 hours each. Solid phase extraction followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS) was used to determine the antibiotic residues. Six of the eight antibiotics studied were detected in the wastewater samples. Both continuous and grab sampling methods indicated that the highest quantities of fluoroquinolones were released in winter followed by the rainy season and the summer. No temporal pattern in antibiotic release was detected. In general, in a common timeframe, continuous sampling showed less concentration of antibiotics in wastewater as compared to grab sampling. It is suggested that continuous sampling should be the method of choice as grab sampling gives erroneous results, it being indicative of the quantities of antibiotics present in wastewater only at the time of sampling. Based on our studies, calculations indicate that from hospitals in India, an estimated 89, 1 and 25 ng/L/day of fluroquinolones, metronidazole and sulfamethoxazole respectively, might be getting released into the

  9. Seasonal and temporal variation in release of antibiotics in hospital wastewater: estimation using continuous and grab sampling.

    Directory of Open Access Journals (Sweden)

    Vishal Diwan

    Full Text Available The presence of antibiotics in the environment and their subsequent impact on resistance development has raised concerns globally. Hospitals are a major source of antibiotics released into the environment. To reduce these residues, research to improve knowledge of the dynamics of antibiotic release from hospitals is essential. Therefore, we undertook a study to estimate seasonal and temporal variation in antibiotic release from two hospitals in India over a period of two years. For this, 6 sampling sessions of 24 hours each were conducted in the three prominent seasons of India, at all wastewater outlets of the two hospitals, using continuous and grab sampling methods. An in-house wastewater sampler was designed for continuous sampling. Eight antibiotics from four major antibiotic groups were selected for the study. To understand the temporal pattern of antibiotic release, each of the 24-hour sessions were divided in three sub-sampling sessions of 8 hours each. Solid phase extraction followed by liquid chromatography/tandem mass spectrometry (LC-MS/MS was used to determine the antibiotic residues. Six of the eight antibiotics studied were detected in the wastewater samples. Both continuous and grab sampling methods indicated that the highest quantities of fluoroquinolones were released in winter followed by the rainy season and the summer. No temporal pattern in antibiotic release was detected. In general, in a common timeframe, continuous sampling showed less concentration of antibiotics in wastewater as compared to grab sampling. It is suggested that continuous sampling should be the method of choice as grab sampling gives erroneous results, it being indicative of the quantities of antibiotics present in wastewater only at the time of sampling. Based on our studies, calculations indicate that from hospitals in India, an estimated 89, 1 and 25 ng/L/day of fluroquinolones, metronidazole and sulfamethoxazole respectively, might be getting

  10. Attitudes to Gun Control in an American Twin Sample: Sex Differences in the Causes of Variation.

    Science.gov (United States)

    Eaves, Lindon J; Silberg, Judy L

    2017-10-01

    The genetic and social causes of individual differences in attitudes to gun control are estimated in a sample of senior male and female twin pairs in the United States. Genetic and environmental parameters were estimated by weighted least squares applied to polychoric correlations for monozygotic (MZ) and dizygotic (DZ) twins of both sexes. The analysis suggests twin similarity for attitudes to gun control in men is entirely genetic while that in women is purely social. Although the volunteer sample is small, the analysis illustrates how the well-tested concepts and methods of genetic epidemiology may be a fertile resource for deepening our scientific understanding of biological and social pathways that affect individual risk to gun violence.

  11. Between- and within-sex variation in hormonal responses to psychological stress in a large sample of college students.

    Science.gov (United States)

    Maestripieri, Dario; Baran, Nicole M; Sapienza, Paola; Zingales, Luigi

    2010-09-01

    This study investigated (1) sex differences in hormonal responses to psychosocial stress; (2) the relation between variability in pre-test hormone concentrations and stress-induced hormonal changes; and (3) some possible sources of within-sex variation in pre-test hormone concentrations and in hormonal responses to the test in a large human subject population. To this end, changes in salivary concentrations of testosterone and cortisol in response to a mild psychosocial stressor (a set of computerized economic decision-making tests) were measured in a sample of over 500 MBA students. Males had higher concentrations of testosterone and cortisol than females both before and after the test. After taking effects of time of testing on hormone concentrations into account, testosterone showed a post-test decrease in males but not in females. Cortisol level increased in both sexes but the post-test increase was larger in females than in males. At the individual level, the pre-test concentrations of testosterone and cortisol predicted both the direction and the magnitude of the post-test hormone change, so that low pre-test hormone concentrations showed large post-test increases whereas high pre-test concentrations showed large post-test decreases. Within-sex variation in hormone concentrations was not accounted for by variation in 2D:4D digit length ratio, a marker of prenatal androgen exposure, but by social variables. Single males without a stable romantic partner had higher testosterone level than males with stable partners, and both males and females without a partner showed a greater cortisol response to the test than married individuals with or without children. Studies conducted with large sample sizes such as this one can help understand normative patterns of hormonal responses to psychosocial stimuli as well as identify the sources of interindividual variation in endocrine function.

  12. Variational perturbation and extended Plefka approaches to dynamics on random networks: the case of the kinetic Ising model

    Science.gov (United States)

    Bachschmid-Romano, L.; Battistin, C.; Opper, M.; Roudi, Y.

    2016-10-01

    We describe and analyze some novel approaches for studying the dynamics of Ising spin glass models. We first briefly consider the variational approach based on minimizing the Kullback-Leibler divergence between independent trajectories and the real ones and note that this approach only coincides with the mean field equations from the saddle point approximation to the generating functional when the dynamics is defined through a logistic link function, which is the case for the kinetic Ising model with parallel update. We then spend the rest of the paper developing two ways of going beyond the saddle point approximation to the generating functional. In the first one, we develop a variational perturbative approximation to the generating functional by expanding the action around a quadratic function of the local fields and conjugate local fields whose parameters are optimized. We derive analytical expressions for the optimal parameters and show that when the optimization is suitably restricted, we recover the mean field equations that are exact for the fully asymmetric random couplings (Mézard and Sakellariou 2011 J. Stat. Mech. 2011 L07001). However, without this restriction the results are different. We also describe an extended Plefka expansion in which in addition to the magnetization, we also fix the correlation and response functions. Finally, we numerically study the performance of these approximations for Sherrington-Kirkpatrick type couplings for various coupling strengths and the degrees of coupling symmetry, for both temporally constant but random, as well as time varying external fields. We show that the dynamical equations derived from the extended Plefka expansion outperform the others in all regimes, although it is computationally more demanding. The unconstrained variational approach does not perform well in the small coupling regime, while it approaches dynamical TAP equations of (Roudi and Hertz 2011 J. Stat. Mech. 2011 P03031) for strong couplings.

  13. Variation in distress among women with infertility: evidence from a population-based sample

    DEFF Research Database (Denmark)

    Greil, Arthur L; Shreffler, Karina M; Schmidt, Lone

    2011-01-01

    for Epidemiological Studies-Depression. Multiple regression analysis was conducted on self-report data (based on a telephone interview) from a probability-based sample of US women aged 25-45 years. We compare women with infertility who have had a prior pregnancy (secondary infertility, n = 628) to women...... with infertility with no prior pregnancies (primary infertility, n = 399). We further distinguish between women with infertility who were actually 'trying' to become pregnant (the infertile with intent) with those who met the medical definition of infertile but did not describe themselves as trying to become...

  14. Capturing temporal variation in phosphorus dynamics in groundwater dominated rivers using automated high-frequency sampling

    Science.gov (United States)

    Bieroza, M. Z.; Heathwaite, A. L.; Mullinger, N. J.; Keenan, P. O.

    2012-04-01

    High-frequency river water quality monitoring provides detailed hydrochemical information on the time scale of hydrologic response. Several studies (Kirchner et al., 2004; Johnes, 2007; Cassidy and Jordan, 2011) have shown previously that coarse sampling approaches fail to quantify nutrient and sediment loads and to capture the fine structure of water quality dynamics correctly. A robust analysis of high-frequency nutrient and water quality time series can present a complex conceptual, analytical and computational problem. High-frequency nutrient monitoring provides new evidence of processes and patterns that could not be observed previously using standard coarse resolution sampling schemes. However, to fully utilise the wealth of information contained in high-frequency nutrient data, we need to address the following questions: how to detect complex coupling patterns and processes in high-resolution flow-nutrients data, how do these patterns and processes change throughout the period of observation, and how to distinguish noise signals from an evidence of real processes (Harris and Heathwaite, 2005). Here, hourly measurements of total phosphorus (TP), soluble reactive phosphorus (SRP) and turbidity were carried out using bank side analysers to study the biogeochemical response of a 54 km2 catchment of the River Leith, a tributary of the River Eden (Cumbria, UK). A remote automated mobile lab facilitates real-time high-frequency nutrient and water quality monitoring, with no time delay between collection and analysis of the reactive elements. The objectives of this study were two-fold: first to investigate the intrinsic complexity of the temporal relationship between phosphorus fractions (SRP, TP), turbidity and continuous hydrometric time series and secondly to investigate the possibilities of missing high-frequency phosphorus data infilling using continuous hydrometric time series. Complex non-linear relationships between flow, TP and SRP, turbidity were observed

  15. Experiments with central-limit properties of spatial samples from locally covariant random fields

    Science.gov (United States)

    Barringer, T.H.; Smith, T.E.

    1992-01-01

    When spatial samples are statistically dependent, the classical estimator of sample-mean standard deviation is well known to be inconsistent. For locally dependent samples, however, consistent estimators of sample-mean standard deviation can be constructed. The present paper investigates the sampling properties of one such estimator, designated as the tau estimator of sample-mean standard deviation. In particular, the asymptotic normality properties of standardized sample means based on tau estimators are studied in terms of computer experiments with simulated sample-mean distributions. The effects of both sample size and dependency levels among samples are examined for various value of tau (denoting the size of the spatial kernel for the estimator). The results suggest that even for small degrees of spatial dependency, the tau estimator exhibits significantly stronger normality properties than does the classical estimator of standardized sample means. ?? 1992.

  16. LONG-TERM VARIABILITY OF BRONCHIAL RESPONSIVENESS TO HISTAMINE IN A RANDOM-POPULATION SAMPLE OF ADULTS

    NARCIS (Netherlands)

    RIJCKEN, B; SCHOUTEN, JP; WEISS, ST; ROSNER, B; DEVRIES, K; VANDERLENDE, R

    1993-01-01

    Long-term variability of bronchial responsiveness has been studied in a random population sample of adults. During a follow-up period of 18 yr, 2,216 subjects contributed 5,012 observations to the analyses. Each subject could have as many as seven observations. Bronchial responsiveness was assessed

  17. Racial variation in response to music in a sample of African-American and Caucasian chronic pain patients.

    Science.gov (United States)

    Siedlecki, Sandra L

    2009-03-01

    The incidence of chronic pain is similar in African-American and Caucasian populations; however, depression and disability secondary to unrelieved chronic pain is higher in African-American populations. In light of this difference, it is important to understand racial variations in response to chronic pain treatments, including complementary therapies such as music. The purpose of this study was to examine racial variation in response to music in an adult population with chronic pain, and specifically to determine if post treatment pain scores differed by race. Secondary analysis from a previously reported randomized controlled trial (n = 60) was used to answer the research questions. Music interventions consisted of listening to music for 1 hour a day for 7 consecutive days. Pain was measured with the McGill Pain Questionnaire short form and a 100-mm visual analog scale. Univariate and multivariate analysis was used to examine differences between groups. Music groups regardless of race experienced a decrease in pain and depression at posttest compared with the control group. However, this difference was only statistically significant for the Caucasian music group. Although our findings demonstrate that music may be an effective intervention for individuals with chronic nonmalignant pain; individuals from different racial backgrounds may respond differently. Further studies are needed to understand these differences in response to music.

  18. Engineering practice variation through provider agreement: a cluster-randomized feasibility trial

    Directory of Open Access Journals (Sweden)

    McCarren M

    2014-10-01

    Full Text Available Madeline McCarren,1 Elaine L Twedt,1 Faizmohamed M Mansuri,2 Philip R Nelson,3 Brian T Peek3 1Pharmacy Benefits Management Services, Department of Veterans Affairs, Hines, IL, 2Wilkes-Barre VA Medical Center, Wilkes-Barre, PA, 3Charles George VA Medical Center, Asheville, NC, USA Purpose: Minimal-risk randomized trials that can be embedded in practice could facilitate learning health-care systems. A cluster-randomized design was proposed to compare treatment strategies by assigning clusters (eg, providers to “favor” a particular drug, with providers retaining autonomy for specific patients. Patient informed consent might be waived, broadening inclusion. However, it is not known if providers will adhere to the assignment or whether institutional review boards will waive consent. We evaluated the feasibility of this trial design.Subjects and methods: Agreeable providers were randomized to “favor” either hydrochlorothiazide or chlorthalidone when starting patients on thiazide-type therapy for hypertension. The assignment applied when the provider had already decided to start a thiazide, and providers could deviate from the strategy as needed. Prescriptions were aggregated to produce a provider strategy-adherence rate.Results: All four institutional review boards waived documentation of patient consent. Providers (n=18 followed their assigned strategy for most of their new thiazide prescriptions (n=138 patients. In the “favor hydrochlorothiazide” group, there was 99% adherence to that strategy. In the “favor chlorthalidone” group, chlorthalidone comprised 77% of new thiazide starts, up from 1% in the pre-study period. When the assigned strategy was followed, dosing in the recommended range was 48% for hydrochlorothiazide (25–50 mg/day and 100% for chlorthalidone (12.5–25.0 mg/day. Providers were motivated to participate by a desire to contribute to a comparative effectiveness study. A study promotional mug, provider information

  19. Albumin to creatinine ratio in a random urine sample: Correlation with severity of preeclampsia

    Directory of Open Access Journals (Sweden)

    Fady S. Moiety

    2014-06-01

    Conclusions: Random urine ACR may be a reliable method for prediction and assessment of severity of preeclampsia. Using the estimated cut-off may add to the predictive value of such a simple quick test.

  20. Evaluation of a Class of Simple and Effective Uncertainty Methods for Sparse Samples of Random Variables and Functions

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Vicente [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bonney, Matthew [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Schroeder, Benjamin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Weirs, V. Gregory [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-11-01

    When very few samples of a random quantity are available from a source distribution of unknown shape, it is usually not possible to accurately infer the exact distribution from which the data samples come. Under-estimation of important quantities such as response variance and failure probabilities can result. For many engineering purposes, including design and risk analysis, we attempt to avoid under-estimation with a strategy to conservatively estimate (bound) these types of quantities -- without being overly conservative -- when only a few samples of a random quantity are available from model predictions or replicate experiments. This report examines a class of related sparse-data uncertainty representation and inference approaches that are relatively simple, inexpensive, and effective. Tradeoffs between the methods' conservatism, reliability, and risk versus number of data samples (cost) are quantified with multi-attribute metrics use d to assess method performance for conservative estimation of two representative quantities: central 95% of response; and 10-4 probability of exceeding a response threshold in a tail of the distribution. Each method's performance is characterized with 10,000 random trials on a large number of diverse and challenging distributions. The best method and number of samples to use in a given circumstance depends on the uncertainty quantity to be estimated, the PDF character, and the desired reliability of bounding the true value. On the basis of this large data base and study, a strategy is proposed for selecting the method and number of samples for attaining reasonable credibility levels in bounding these types of quantities when sparse samples of random variables or functions are available from experiments or simulations.

  1. Sampling

    CERN Document Server

    Thompson, Steven K

    2012-01-01

    Praise for the Second Edition "This book has never had a competitor. It is the only book that takes a broad approach to sampling . . . any good personal statistics library should include a copy of this book." —Technometrics "Well-written . . . an excellent book on an important subject. Highly recommended." —Choice "An ideal reference for scientific researchers and other professionals who use sampling." —Zentralblatt Math Features new developments in the field combined with all aspects of obtaining, interpreting, and using sample data Sampling provides an up-to-date treat

  2. Seasonal variation in tracer movement in a forested experimental plot using manual and automated sampling techniques

    Science.gov (United States)

    Singer, J. H.; Seaman, J. C.; Aburime, S.

    2004-12-01

    In recent years, implications associated with groundwater contamination have increased the efforts of researchers studying solute transport through the unsaturated soil zone near the ground surface (vadose zone). Success in tracking the movement of water, solutes, and the development of vadose zone hydrologic models requires high-quality field data. However, near continuous, spatially distributed soil moisture and matric potential data sets are rare because conventional soil parameter instrumentation is point-based and labor intensive. An automated vadose zone monitoring system (AVM) was developed to complement a set of manually monitored instrument arrays in an effort to address the quality and quantity of data collected in the vadose zone. Tracer (tritium) movement was evaluated for winter and summer irrigation applications on a forested field plot on the Atlantic Coastal Plain in South Carolina. Tritiated water was applied in two pulse events through an irrigation system and breakthrough data were measured from soil cores, suction lysimeters and soil vapor wells in the field. Measured breakthrough data for both winter and summer tracer applications were compared to solute transport solutions and modeled using numerical modeling software. The data from automated and manual sampling systems were used to evaluate the results of a one dimension hydrologic model that predicted the movement of water and a tracer (tritium) movement associated with winter and summer irrigation events.

  3. Genetic variation of 12 X-chromosomal STR loci in an East Timor sample.

    Science.gov (United States)

    Moreira, Helena; Costa, Helena; Tavares, Filipa; Souto, Luís

    2015-03-01

    East Timor (República Democrática de Timor Leste) is a country with a population around 1 million inhabitants located in Southeast Asia and composed of 13 districts, including the eastern half of the Timor Island, Ataúro and Jaco islands, and the coastal enclave of Oecusse-Ambeno located in West Timor. Examples of the importance of X-chromosomal short tandem repeats (STRs) analysis include parentage identification, namely in cases involving father/daughter relationships, paternity in close relative deficiency cases without access to the putative father, maternity testing, and in rape or incest cases. In this study, 149 saliva samples were collected from unrelated individuals from East Timor and 12 X-chromosomal STRs genotyped using Investigator® Argus X-12 kit (Qiagen). A total of 13 alleles not included in Investigator Argus X-12 allelic ladder (off-ladder alleles) were found, four of which never reported (alleles 34.1 and 38.1 at DXS10134, allele 17.2 at DXS10074, and allele 28.1 at DXS10146). Allele 27.3 at DXS10101 and alleles 26, 28, and 29 at DXS10148 have already been observed in other populations but their frequencies are considerably higher in East Timor population. Allele frequencies and population statistic parameters were calculated for East Timor population and data contextualized in Southeast Asia/Pacific Region.

  4. Morphological variation of Gephyrocapsa oceanica Kamptner 1943 in plankton samples: implications for ecologic and taxonomic interpretations.

    Science.gov (United States)

    Bollmann, Jörg; Klaas, Christine

    2008-07-01

    Morphological analysis of Gephyrocapsa spp. in plankton samples confirms the existence of five out of six morphotypes that were previously reported from Holocene sediments. Our data suggest a much higher diversity within the genus Gephyrocapsa than the currently accepted species circumscriptions. Furthermore, we confirm the morphological species delineations made by Kamptner that allow the separation of three morphological groups within the genus Gephyrocapsa: one group with large bridge angles (G. oceanica var. typica Kamptner 1943), a second group with small bridge angles (G. oceanica var. californiensis Kamptner 1956) and a third group of small coccoliths (G. aperta Kamptner 1963). However, a seemingly continuous transition from small to large coccoliths within G. oceanica var. typica along a temperature gradient points either to a high phenotypic plasticity of G. oceanica var. typica or numerous sibling species highly adapted to specific environmental conditions. Testing of these hypotheses is of utmost importance to understanding the diversity of marine plankton and its evolution, and to assessing the impact of future and past environmental change on primary producers such as coccolithophorids.

  5. Identification of Nonstandard Multifractional Brownian Motions under White Noise by Multiscale Local Variations of Its Sample Paths

    Directory of Open Access Journals (Sweden)

    Kwang-Il Ahn

    2013-01-01

    Full Text Available The Hurst exponent and variance are two quantities that often characterize real-life, high-frequency observations. Such real-life signals are generally measured under noise environments. We develop a multiscale statistical method for simultaneous estimation of a time-changing Hurst exponent H(t and a variance parameter C in a multifractional Brownian motion model in the presence of white noise. The method is based on the asymptotic behavior of the local variation of its sample paths which applies to coarse scales of the sample paths. This work provides stable and simultaneous estimators of both parameters when independent white noise is present. We also discuss the accuracy of the simultaneous estimators compared with a few selected methods and the stability of computations with regard to adapted wavelet filters.

  6. Barn owl feathers as biomonitors of mercury: sources of variation in sampling procedures.

    Science.gov (United States)

    Roque, Inês; Lourenço, Rui; Marques, Ana; Coelho, João Pedro; Coelho, Cláudia; Pereira, Eduarda; Rabaça, João E; Roulin, Alexandre

    2016-04-01

    Given their central role in mercury (Hg) excretion and suitability as reservoirs, bird feathers are useful Hg biomonitors. Nevertheless, the interpretation of Hg concentrations is still questioned as a result of a poor knowledge of feather physiology and mechanisms affecting Hg deposition. Given the constraints of feather availability to ecotoxicological studies, we tested the effect of intra-individual differences in Hg concentrations according to feather type (body vs. flight feathers), position in the wing and size (mass and length) in order to understand how these factors could affect Hg estimates. We measured Hg concentration of 154 feathers from 28 un-moulted barn owls (Tyto alba), collected dead on roadsides. Median Hg concentration was 0.45 (0.076-4.5) mg kg(-1) in body feathers, 0.44 (0.040-4.9) mg kg(-1) in primary and 0.60 (0.042-4.7) mg kg(-1) in secondary feathers, and we found a poor effect of feather type on intra-individual Hg levels. We also found a negative effect of wing feather mass on Hg concentration but not of feather length and of its position in the wing. We hypothesize that differences in feather growth rate may be the main driver of between-feather differences in Hg concentrations, which can have implications in the interpretation of Hg concentrations in feathers. Finally, we recommend that, whenever possible, several feathers from the same individual should be analysed. The five innermost primaries have lowest mean deviations to both between-feather and intra-individual mean Hg concentration and thus should be selected under restrictive sampling scenarios.

  7. Beyond Random Walk and Metropolis-Hastings Samplers: Why You Should Not Backtrack for Unbiased Graph Sampling

    CERN Document Server

    Lee, Chul-Ho; Eun, Do Young

    2012-01-01

    Graph sampling via crawling has been actively considered as a generic and important tool for collecting uniform node samples so as to consistently estimate and uncover various characteristics of complex networks. The so-called simple random walk with re-weighting (SRW-rw) and Metropolis-Hastings (MH) algorithm have been popular in the literature for such unbiased graph sampling. However, an unavoidable downside of their core random walks -- slow diffusion over the space, can cause poor estimation accuracy. In this paper, we propose non-backtracking random walk with re-weighting (NBRW-rw) and MH algorithm with delayed acceptance (MHDA) which are theoretically guaranteed to achieve, at almost no additional cost, not only unbiased graph sampling but also higher efficiency (smaller asymptotic variance of the resulting unbiased estimators) than the SRW-rw and the MH algorithm, respectively. In particular, a remarkable feature of the MHDA is its applicability for any non-uniform node sampling like the MH algorithm,...

  8. Identifying the origin of groundwater samples in a multi-layer aquifer system with Random Forest classification

    Science.gov (United States)

    Baudron, Paul; Alonso-Sarría, Francisco; García-Aróstegui, José Luís; Cánovas-García, Fulgencio; Martínez-Vicente, David; Moreno-Brotóns, Jesús

    2013-08-01

    Accurate identification of the origin of groundwater samples is not always possible in complex multilayered aquifers. This poses a major difficulty for a reliable interpretation of geochemical results. The problem is especially severe when the information on the tubewells design is hard to obtain. This paper shows a supervised classification method based on the Random Forest (RF) machine learning technique to identify the layer from where groundwater samples were extracted. The classification rules were based on the major ion composition of the samples. We applied this method to the Campo de Cartagena multi-layer aquifer system, in southeastern Spain. A large amount of hydrogeochemical data was available, but only a limited fraction of the sampled tubewells included a reliable determination of the borehole design and, consequently, of the aquifer layer being exploited. Added difficulty was the very similar compositions of water samples extracted from different aquifer layers. Moreover, not all groundwater samples included the same geochemical variables. Despite of the difficulty of such a background, the Random Forest classification reached accuracies over 90%. These results were much better than the Linear Discriminant Analysis (LDA) and Decision Trees (CART) supervised classification methods. From a total of 1549 samples, 805 proceeded from one unique identified aquifer, 409 proceeded from a possible blend of waters from several aquifers and 335 were of unknown origin. Only 468 of the 805 unique-aquifer samples included all the chemical variables needed to calibrate and validate the models. Finally, 107 of the groundwater samples of unknown origin could be classified. Most unclassified samples did not feature a complete dataset. The uncertainty on the identification of training samples was taken in account to enhance the model. Most of the samples that could not be identified had an incomplete dataset.

  9. Soil map disaggregation improved by soil-landscape relationships, area-proportional sampling and random forest implementation

    DEFF Research Database (Denmark)

    Møller, Anders Bjørn; Malone, Brendan P.; Odgers, Nathan

    algorithm were evaluated. The resulting maps were validated on 777 soil profiles situated in a grid covering Denmark. The experiments showed that the results obtained with Jacobsen’s map were more accurate than the results obtained with the CEC map, despite a nominally coarser scale of 1:2,000,000 vs. 1...... of European Communities (CEC, 1985) respectively, both using the FAO 1974 classification. Furthermore, the effects of implementing soil-landscape relationships, using area proportional sampling instead of per polygon sampling, and replacing the default C5.0 classification tree algorithm with a random forest......:1,000,000. This finding is probably related to the fact that Jacobsen’s map was more detailed with a larger number of polygons, soil map units and soil types, despite its coarser scale. The results showed that the implementation of soil-landscape relationships, area-proportional sampling and the random forest...

  10. Elemental and topographical imaging of microscopic variations in deposition on NSTX-U and DIII-D samples

    Science.gov (United States)

    Skinner, C. H.; Kaita, R.; Koel, B. E.; Chrobak, C. P.; Wampler, W. R.

    2017-10-01

    Tokamak plasma facing components (PFCs) have surface roughness that can cause microscopic spatial variations in erosion and deposition and hence influence material migration. Previous RBS measurements showed indirect evidence for this but the spatial (0.5mm) resolution was insufficient for direct imaging. We will present elemental images at sub-micron resolution of deposition on NSTX-U and DiMES samples that show strong microscopic variations and correlate this with 3D topographical maps of surface irregularities. The elemental imaging is performed with a Scanning Auger Microprobe (SAM) that measures element-specific Auger electrons excited by an SEM electron beam. 3D topographical maps of the samples are performed with a Leica DCM 3D confocal light microscope and compared to the elemental deposition pattern. The initial results appear consistent with erosion at the downstream edges of the surface pores exposed to the incident ion flux, whereas the deeper regions are shadowed and serve as deposition traps. Support was provided through DOE Contract Numbers DE-AC02-09CH11466, DE-FC02-04ER54698 and DE-NA0003525.

  11. Comparative study of microfacies variation in two samples from the Chittenango member, Marcellus shale subgroup, western New York state, USA

    Energy Technology Data Exchange (ETDEWEB)

    Balulla, Shama, E-mail: shamamohammed77@outlook.com; Padmanabhan, E., E-mail: eswaran-padmanabhan@petronas.com.my [Department of Geoscience, Faculty of Geosciencs and Petroleum Engineering Universiti Teknologi PETRONAS, Tronoh (Malaysia); Over, Jeffrey, E-mail: over@geneseo.edu [Department of geological sciences, Geneseo, NY (United States)

    2015-07-22

    This study demonstrates the significant lithologic variations that occur within the two shale samples from the Chittenango member of the Marcellus shale formation from western New York State in terms of mineralogical composition, type of lamination, pyrite occurrences and fossil content using thin section detailed description and field emission Scanning electron microscope (FESEM) with energy dispersive X-Ray Spectrum (EDX). This study is classified samples as laminated clayshale and fossiliferous carbonaceous shale. The most important detrital constituents of these shales are the clay mineral illite and chlorite, quartz, organic matter, carbonate mineral, and pyrite. The laminated clayshale has a lower amount of quartz and carbonate minerals than fossiliferous carbonaceous shale while it has a higher amount of clay minerals (chlorite and illite) and organic matter. FESEM analysis confirms the presence of chlorite and illite. The fossil content in the laminated clayshale is much lower than the fossiliferous carbonaceous shale. This can provide greater insights about variations in the depositional and environmental factors that influenced its deposition. This result can be compiled with the sufficient data to be helpful for designing the horizontal wells and placement of hydraulic fracturing in shale gas exploration and production.

  12. Saturation sampling for spatial variation in multiple air pollutants across an inversion-prone metropolitan area of complex terrain

    Science.gov (United States)

    2014-01-01

    Background Characterizing intra-urban variation in air quality is important for epidemiological investigation of health outcomes and disparities. To date, however, few studies have been designed to capture spatial variation during select hours of the day, or to examine the roles of meteorology and complex terrain in shaping intra-urban exposure gradients. Methods We designed a spatial saturation monitoring study to target local air pollution sources, and to understand the role of topography and temperature inversions on fine-scale pollution variation by systematically allocating sampling locations across gradients in key local emissions sources (vehicle traffic, industrial facilities) and topography (elevation) in the Pittsburgh area. Street-level integrated samples of fine particulate matter (PM2.5), black carbon (BC), nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3) were collected during morning rush and probable inversion hours (6-11 AM), during summer and winter. We hypothesized that pollution concentrations would be: 1) higher under inversion conditions, 2) exacerbated in lower-elevation areas, and 3) vary by season. Results During July - August 2011 and January - March 2012, we observed wide spatial and seasonal variability in pollution concentrations, exceeding the range measured at regulatory monitors. We identified elevated concentrations of multiple pollutants at lower-elevation sites, and a positive association between inversion frequency and NO2 concentration. We examined temporal adjustment methods for deriving seasonal concentration estimates, and found that the appropriate reference temporal trend differs between pollutants. Conclusions Our time-stratified spatial saturation approach found some evidence for modification of inversion-concentration relationships by topography, and provided useful insights for refining and interpreting GIS-based pollution source indicators for Land Use Regression modeling. PMID:24735818

  13. Non-random seasonal variation in the structure of a Mediterranean snake community

    Directory of Open Access Journals (Sweden)

    E. Filippi

    2007-05-01

    Full Text Available The community structure in relation to habitat type was studied in a Mediterranean community of snakes from Canale Monterano, central Italy. Habitat data for snakes were analysed both overall and divided by season, i.e. spring (April–June and summer (July–September. Community analyses were performed using null models (RA2 and RA3 algorithms and Monte Carlo simulations on habitat niche overlap estimates. Null models suggested that the community was assembled non-randomly (according to RA2 but not RA3, indicating that the generalist-specialist nature (the number of resource states, but not necessarily the types used by each species in the assemblage reduced ecological similarity. Similar results were reached also performing the same null model procedures on the spring datasets, whereas no structure emerged during summer either by RA2 or RA3 algorithms. In general, this study suggests that the community structure of snakes during spring may be shaped by the different eco-physiological needs of the various species (probably, the differential tolerance to cold and the consequent needs of finding suitable hibernacula, whereas the lack of structure during summer may be caused by the between-species similar foraging needs.

  14. A block variational procedure for the iterative diagonalization of non-Hermitian random-phase approximation matrices.

    Science.gov (United States)

    Rocca, Dario; Bai, Zhaojun; Li, Ren-Cang; Galli, Giulia

    2012-01-21

    We present a technique for the iterative diagonalization of random-phase approximation (RPA) matrices, which are encountered in the framework of time-dependent density-functional theory (TDDFT) and the Bethe-Salpeter equation. The non-Hermitian character of these matrices does not permit a straightforward application of standard iterative techniques used, i.e., for the diagonalization of ground state Hamiltonians. We first introduce a new block variational principle for RPA matrices. We then develop an algorithm for the simultaneous calculation of multiple eigenvalues and eigenvectors, with convergence and stability properties similar to techniques used to iteratively diagonalize Hermitian matrices. The algorithm is validated for simple systems (Na(2) and Na(4)) and then used to compute multiple low-lying TDDFT excitation energies of the benzene molecule. © 2012 American Institute of Physics

  15. Genetic variations of Lansium domesticum Corr. accessions from Java, Sumatra and Ceram based on Random Amplified Polymorphic DNA fingerprints

    Directory of Open Access Journals (Sweden)

    KUSUMADEWI SRI YULITA

    2011-07-01

    Full Text Available Yulita KS (2011 Genetic variations of Lansium domesticum Corr. accessions from Java, Bengkulu and Ceram based on Random Amplified Polymorphic DNA fingerprints. Biodiversitas 12: 125-130. Duku (Lansium domesticum Corr. is one of popular tropical fruits in SE Asia. The spesies has three varieties, known as duku, langsat and kokosan; and duku is the most popular one for being the sweetiest fruit. Indonesia has several local varieties of duku, such as duku Condet, duku Sumber and duku Palembang. This present study aimed to assess genetic diversity of 47 accessions of duku from Java, Sumatra, and Ceram based on RAPD fingerprints. Ten RAPD’s primers were initially screened and five were selected for the analysis. These five primers (OPA 7, 13, 18, OPB 7, and OPN 12 generated 53 scorable bands with an average of 10.6 polymorphic fragment per primer. Percentage of polymorphism ranged from 16.89% (OPA 7 and OPN 12 to 24.54% (OPB 7 with an average of 20.16% polymorphism. OPB 7 at 450 bp was exclusively possessed by accession 20 (Java, OPA 18 at 500 bp was by accession 6 (Java, 550 bp by 3 clones from Bengkulu. While OPN 12 at 300 bp and OPA 13 at 450 bp were shared among the accessions. Clustering analysis was performed based on RAPD profiles using the UPGMA method. The range of genetic similarity value among accessions was 0.02-0.65 suggesting high variation of gene pool existed among accessions.

  16. Variations in reporting of outcomes in randomized trials on diet and physical activity in pregnancy: A systematic review.

    Science.gov (United States)

    Rogozińska, Ewelina; Marlin, Nadine; Yang, Fen; Dodd, Jodie M; Guelfi, Kym; Teede, Helena; Surita, Fernanda; Jensen, Dorte M; Geiker, Nina R W; Astrup, Arne; Yeo, SeonAe; Kinnunen, Tarja I; Stafne, Signe N; Cecatti, Jose G; Bogaerts, Annick; Hauner, Hans; Mol, Ben W; Scudeller, Tânia T; Vinter, Christina A; Renault, Kristina M; Devlieger, Roland; Thangaratinam, Shakila; Khan, Khalid S

    2017-07-01

    Trials on diet and physical activity in pregnancy report on various outcomes. We aimed to assess the variations in outcomes reported and their quality in trials on lifestyle interventions in pregnancy. We searched major databases without language restrictions for randomized controlled trials on diet and physical activity-based interventions in pregnancy up to March 2015. Two independent reviewers undertook study selection and data extraction. We estimated the percentage of papers reporting 'critically important' and 'important' outcomes. We defined the quality of reporting as a proportion using a six-item questionnaire. Regression analysis was used to identify factors affecting this quality. Sixty-six randomized controlled trials were published in 78 papers (66 main, 12 secondary). Gestational diabetes (57.6%, 38/66), preterm birth (48.5%, 32/66) and cesarian section (60.6%, 40/66), were the commonly reported 'critically important' outcomes. Gestational weight gain (84.5%, 56/66) and birth weight (87.9%, 58/66) were reported in most papers, although not considered critically important. The median quality of reporting was 0.60 (interquartile range 0.25, 0.83) for a maximum score of one. Study and journal characteristics did not affect quality. Many studies on lifestyle interventions in pregnancy do not report critically important outcomes, highlighting the need for core outcome set development. © 2017 Japan Society of Obstetrics and Gynecology.

  17. Intraoperative monitoring of stroke volume variation versus central venous pressure in laparoscopic liver surgery: a randomized prospective comparative trial.

    Science.gov (United States)

    Ratti, Francesca; Cipriani, Federica; Reineke, Raffaella; Catena, Marco; Paganelli, Michele; Comotti, Laura; Beretta, Luigi; Aldrighetti, Luca

    2016-02-01

    Central venous pressure (CVP) is used as a marker of cardiac preload to control intraoperative blood loss in open hepatectomies, while its reliability in laparoscopy is less certain. The aim of this randomized prospective trial was to evaluate the outcome of laparoscopic resections performed with stroke volume variation (SVV) or CVP monitoring. All candidates for laparoscopic liver resection were assigned randomly to SVV or to CVP groups. Outcome was evaluated included conversion rate, cause of conversion, intraoperative blood loss, need for transfusions, length of surgery and postoperative results. Ninety consecutive patients were enrolled: both SVV and CVP groups included 45 patients each and were comparable in terms of patient and disease characteristics. A reduced rate of conversion was recorded in the SVV compared to the CVP group (6.7% and 17.8% respectively, p = 0.02). Blood loss was lower in the SVV group (150 mL), compared to the CVP group (300 mL, p = 0.04). Morbidity, mortality, length of stay and functional recovery were comparable. On multivariate analysis, lesion location, extent of hepatectomy and type of cardiac preload monitoring were associated significantly to risk of conversion. SVV monitoring in laparoscopic liver surgery improves intraoperative outcome, thus enhancing the benefits of the minimally-invasive approach and fast-track protocols. Copyright © 2015 International Hepato-Pancreato-Biliary Association Inc. Published by Elsevier Ltd. All rights reserved.

  18. Randomization tests

    CERN Document Server

    Edgington, Eugene

    2007-01-01

    Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani

  19. Finite-sample corrected generalized estimating equation of population average treatment effects in stepped wedge cluster randomized trials.

    Science.gov (United States)

    Scott, JoAnna M; deCamp, Allan; Juraska, Michal; Fay, Michael P; Gilbert, Peter B

    2017-04-01

    Stepped wedge designs are increasingly commonplace and advantageous for cluster randomized trials when it is both unethical to assign placebo, and it is logistically difficult to allocate an intervention simultaneously to many clusters. We study marginal mean models fit with generalized estimating equations for assessing treatment effectiveness in stepped wedge cluster randomized trials. This approach has advantages over the more commonly used mixed models that (1) the population-average parameters have an important interpretation for public health applications and (2) they avoid untestable assumptions on latent variable distributions and avoid parametric assumptions about error distributions, therefore, providing more robust evidence on treatment effects. However, cluster randomized trials typically have a small number of clusters, rendering the standard generalized estimating equation sandwich variance estimator biased and highly variable and hence yielding incorrect inferences. We study the usual asymptotic generalized estimating equation inferences (i.e., using sandwich variance estimators and asymptotic normality) and four small-sample corrections to generalized estimating equation for stepped wedge cluster randomized trials and for parallel cluster randomized trials as a comparison. We show by simulation that the small-sample corrections provide improvement, with one correction appearing to provide at least nominal coverage even with only 10 clusters per group. These results demonstrate the viability of the marginal mean approach for both stepped wedge and parallel cluster randomized trials. We also study the comparative performance of the corrected methods for stepped wedge and parallel designs, and describe how the methods can accommodate interval censoring of individual failure times and incorporate semiparametric efficient estimators.

  20. Securing image information using double random phase encoding and parallel compressive sensing with updated sampling processes

    Science.gov (United States)

    Hu, Guiqiang; Xiao, Di; Wang, Yong; Xiang, Tao; Zhou, Qing

    2017-11-01

    Recently, a new kind of image encryption approach using compressive sensing (CS) and double random phase encoding has received much attention due to the advantages such as compressibility and robustness. However, this approach is found to be vulnerable to chosen plaintext attack (CPA) if the CS measurement matrix is re-used. Therefore, designing an efficient measurement matrix updating mechanism that ensures resistance to CPA is of practical significance. In this paper, we provide a novel solution to update the CS measurement matrix by altering the secret sparse basis with the help of counter mode operation. Particularly, the secret sparse basis is implemented by a reality-preserving fractional cosine transform matrix. Compared with the conventional CS-based cryptosystem that totally generates all the random entries of measurement matrix, our scheme owns efficiency superiority while guaranteeing resistance to CPA. Experimental and analysis results show that the proposed scheme has a good security performance and has robustness against noise and occlusion.

  1. EARLY HEAD START FAMILIES' EXPERIENCES WITH STRESS: UNDERSTANDING VARIATIONS WITHIN A HIGH-RISK, LOW-INCOME SAMPLE.

    Science.gov (United States)

    Hustedt, Jason T; Vu, Jennifer A; Bargreen, Kaitlin N; Hallam, Rena A; Han, Myae

    2017-09-01

    The federal Early Head Start program provides a relevant context to examine families' experiences with stress since participants qualify on the basis of poverty and risk. Building on previous research that has shown variations in demographic and economic risks even among qualifying families, we examined possible variations in families' perceptions of stress. Family, parent, and child data were collected to measure stressors and risk across a variety of domains in families' everyday lives, primarily from self-report measures, but also including assay results from child cortisol samples. A cluster analysis was employed to examine potential differences among groups of Early Head Start families. Results showed that there were three distinct subgroups of families, with some families perceiving that they experienced very high levels of stress while others perceived much lower levels of stress despite also experiencing poverty and heightened risk. These findings have important implications in that they provide an initial step toward distinguishing differences in low-income families' experiences with stress, thereby informing interventions focused on promoting responsive caregiving as a possible mechanism to buffer the effects of family and social stressors on young children. © 2017 Michigan Association for Infant Mental Health.

  2. Alcohol and marijuana use in adolescents' daily lives: a random sample of experiences.

    Science.gov (United States)

    Larson, R; Csikszentmihalyi, M; Freeman, M

    1984-07-01

    High school students filled out reports on their experiences at random times during their daily lives, including 48 occasions when they were using alcohol or marijuana. Alcohol use was reported primarily in the context of Friday and Saturday night social gatherings and was associated with a happy and gregarious subjective state. Marijuana use was reported across a wider range of situations and was associated with an average state that differed much less from ordinary experience.

  3. Stemflow estimation in a redwood forest using model-based stratified random sampling

    Science.gov (United States)

    Jack Lewis

    2003-01-01

    Model-based stratified sampling is illustrated by a case study of stemflow volume in a redwood forest. The approach is actually a model-assisted sampling design in which auxiliary information (tree diameter) is utilized in the design of stratum boundaries to optimize the efficiency of a regression or ratio estimator. The auxiliary information is utilized in both the...

  4. Random or systematic sampling to detect a localised microbial contamination within a batch of food

    NARCIS (Netherlands)

    Jongenburger, I.; Reij, M.W.; Boer, E.P.J.; Gorris, L.G.M.; Zwietering, M.H.

    2011-01-01

    Pathogenic microorganisms are known to be distributed heterogeneously in food products that are solid, semi-solid or powdered, like for instance peanut butter, cereals, or powdered milk. This complicates effective detection of the pathogens by sampling. Two-class sampling plans, which are deployed

  5. Multistage point relascope and randomized branch sampling for downed coarse woody debris estimation

    Science.gov (United States)

    Jeffrey H. Gove; Mark J. Ducey; Harry T. Valentine

    2002-01-01

    New sampling methods have recently been introduced that allow estimation of downed coarse woody debris using an angle gauge, or relascope. The theory behind these methods is based on sampling straight pieces of downed coarse woody debris. When pieces deviate from this ideal situation, auxillary methods must be employed. We describe a two-stage procedure where the...

  6. Significance of major and minor element variations in plagioclase in sodic ferrogabbro and breccia matrix in lunar highlands sample 67915

    Science.gov (United States)

    Weiblen, P. W.; Day, W. C.; Miller, J. D., Jr.

    1980-01-01

    Attention is given to the significance of the results of a study of Ca, K, Ti, Fe, Mn, and Mg variations in plagioclase in highlands sample 67915,84. This polymict breccia from Outhouse Rock station 11 at the Apollo 16 site has been selected for study because it contains a wide variety of clast types, including a differentiated type-sodic ferrogabbro. It is found that the data on Ca, K, Ti, Fe, Mn, and Mg in plagioclase show no evidence of reaction between sodic ferrogabbro and breccia matrix clasts. Two groups of plagioclase compositions have been recognized in the breccia matrix. The data suggest that the prebreccia characteristics of plagioclase compositions have been preserved in 67915. Data on Mg/(Mg+FE) ratios suggest that the sodic ferrogabbro and the intermediate-Ca plagioclase clasts could be related to the Mg-rich plutonic rock suite and the high-Ca plagioclase clasts to the ferroan anorthosites.

  7. Features of surfaces with random structure variations: Poster at Strategic Workshop "Principles and Development of Bio-Inspired Materials", 13 - 15 April 2010; Vienna, Austria

    OpenAIRE

    Mölders, N.; Nellesen, A.; Bertling, J.

    2010-01-01

    In contrast to the precision requested in industrial processing, biological structures only seem to possess a perfect, uniform regularity. Within the recurring patterns and periodic self-similar structures a randomly acting variation appears to be present. The main goal of this work is to elucidate whether these variations are irrelevant or related to the particular functionality of a surface or if they are just a result of stimulus- environmental interaction and genetical predisposition. The...

  8. Significant performance variation among PCR systems in diagnosing congenital toxoplasmosis in São Paulo, Brazil: analysis of 467 amniotic fluid samples.

    Science.gov (United States)

    Okay, Thelma Suely; Yamamoto, Lidia; Oliveira, Léa Campos; Manuli, Erika Regina; Andrade Junior, Heitor Franco de; Del Negro, Gilda Maria Barbaro

    2009-01-01

    Performance variation among PCR systems in detecting Toxoplasma gondii has been extensively reported and associated with target genes, primer composition, amplification parameters, treatment during pregnancy, host genetic susceptibility and genotypes of different parasites according to geographical characteristics. A total of 467 amniotic fluid samples from T. gondii IgM- and IgG-positive Brazilian pregnant women being treated for 1 to 6 weeks at the time of amniocentesis (gestational ages of 14 to 25 weeks). One nested-B1-PCR and three one-round amplification systems targeted to rDNA, AF146527 and the B1 gene were employed. Of the 467 samples, 189 (40.47%) were positive for one-round amplifications: 120 (63.49%) for the B1 gene, 24 (12.69%) for AF146527, 45 (23.80%) for both AF146527 and the B1 gene, and none for rDNA. Fifty previously negative one-round PCR samples were chosen by computer-assisted randomization analysis and re-tested (nested-B1-PCR), during which nine additional cases were detected (9/50 or 18%). The B1 gene PCR was far more sensitive than the AF146527 PCR, and the rDNA PCR was the least effective even though the rDNA had the most repetitive sequence. Considering that the four amplification systems were equally affected by treatment, that the amplification conditions were optimized for the target genes and that most of the primers have already been reported, it is plausible that the striking differences found among PCR performances could be associated with genetic diversity in patients and/or with different Toxoplasma gondii genotypes occurring in Brazil. The use of PCR for the diagnosis of fetal Toxoplasma infections in Brazil should be targeted to the B1 gene when only one gene can be amplified, preferably by nested amplification with primers B22/B23.

  9. Significant performance variation among PCR systems in diagnosing congenital toxoplasmosis in São Paulo, Brazil: analysis of 467 amniotic fluid samples

    Directory of Open Access Journals (Sweden)

    Thelma Suely Okay

    2009-03-01

    Full Text Available INTRODUCTION: Performance variation among PCR systems in detecting Toxoplasma gondii has been extensively reported and associated with target genes, primer composition, amplification parameters, treatment during pregnancy, host genetic susceptibility and genotypes of different parasites according to geographical characteristics. PATIENTS: A total of 467 amniotic fluid samples from T. gondii IgM- and IgG-positive Brazilian pregnant women being treated for 1 to 6 weeks at the time of amniocentesis (gestational ages of 14 to 25 weeks. METHODS: One nested-B1-PCR and three one-round amplification systems targeted to rDNA, AF146527 and the B1 gene were employed. RESULTS: Of the 467 samples, 189 (40.47% were positive for one-round amplifications: 120 (63.49% for the B1 gene, 24 (12.69% for AF146527, 45 (23.80% for both AF146527 and the B1 gene, and none for rDNA. Fifty previously negative one-round PCR samples were chosen by computer-assisted randomization analysis and re-tested (nested-B1-PCR, during which nine additional cases were detected (9/50 or 18%. DISCUSSION: The B1 gene PCR was far more sensitive than the AF146527 PCR, and the rDNA PCR was the least effective even though the rDNA had the most repetitive sequence. Considering that the four amplification systems were equally affected by treatment, that the amplification conditions were optimized for the target genes and that most of the primers have already been reported, it is plausible that the striking differences found among PCR performances could be associated with genetic diversity in patients and/or with different Toxoplasma gondii genotypes occurring in Brazil. CONCLUSION: The use of PCR for the diagnosis of fetal Toxoplasma infections in Brazil should be targeted to the B1 gene when only one gene can be amplified, preferably by nested amplification with primers B22/B23.

  10. Non-random expression of ribosomal DNA units in a grasshopper showing high intragenomic variation for the ITS2 region.

    Science.gov (United States)

    Ruiz-Estévez, M; Ruiz-Ruano, F J; Cabrero, J; Bakkali, M; Perfectti, F; López-León, M D; Camacho, J P M

    2015-06-01

    We analyse intragenomic variation of the ITS2 internal transcribed spacer of ribosomal DNA (rDNA) in the grasshopper Eyprepocnemis plorans, by means of tagged PCR 454 amplicon sequencing performed on both genomic DNA (gDNA) and RNA-derived complementary DNA (cDNA), using part of the ITS2 flanking coding regions (5.8S and 28S rDNA) as an internal control for sequencing errors. Six different ITS2 haplotypes (i.e. variants for at least one nucleotide in the complete ITS2 sequence) were found in a single population, one of them (Hap4) being specific to a supernumerary (B) chromosome. The analysis of both gDNA and cDNA from the same individuals provided an estimate of the expression efficiency of the different haplotypes. We found random expression (i.e. about similar recovery in gDNA and cDNA) for three haplotypes (Hap1, Hap2 and Hap5), but significant underexpression for three others (Hap3, Hap4 and Hap6). Hap4 was the most extremely underexpressed and, remarkably, it showed the lowest sequence conservation for the flanking 5.8-28S coding regions in the gDNA reads but the highest conservation (100%) in the cDNA ones, suggesting the preferential expression of mutation-free rDNA units carrying this ITS2 haplotype. These results indicate that the ITS2 region of rDNA is far from complete homogenization in this species, and that the different rDNA units are not expressed at random, with some of them being severely downregulated. © 2015 The Royal Entomological Society.

  11. Random sampling technique for ultra-fast computations of molecular opacities for exoplanet atmospheres

    Science.gov (United States)

    Min, M.

    2017-10-01

    Context. Opacities of molecules in exoplanet atmospheres rely on increasingly detailed line-lists for these molecules. The line lists available today contain for many species up to several billions of lines. Computation of the spectral line profile created by pressure and temperature broadening, the Voigt profile, of all of these lines is becoming a computational challenge. Aims: We aim to create a method to compute the Voigt profile in a way that automatically focusses the computation time into the strongest lines, while still maintaining the continuum contribution of the high number of weaker lines. Methods: Here, we outline a statistical line sampling technique that samples the Voigt profile quickly and with high accuracy. The number of samples is adjusted to the strength of the line and the local spectral line density. This automatically provides high accuracy line shapes for strong lines or lines that are spectrally isolated. The line sampling technique automatically preserves the integrated line opacity for all lines, thereby also providing the continuum opacity created by the large number of weak lines at very low computational cost. Results: The line sampling technique is tested for accuracy when computing line spectra and correlated-k tables. Extremely fast computations ( 3.5 × 105 lines per second per core on a standard current day desktop computer) with high accuracy (≤1% almost everywhere) are obtained. A detailed recipe on how to perform the computations is given.

  12. Hybrid random walk-linear discriminant analysis method for unwrapping quantitative phase microscopy images of biological samples

    Science.gov (United States)

    Kim, Diane N. H.; Teitell, Michael A.; Reed, Jason; Zangle, Thomas A.

    2015-11-01

    Standard algorithms for phase unwrapping often fail for interferometric quantitative phase imaging (QPI) of biological samples due to the variable morphology of these samples and the requirement to image at low light intensities to avoid phototoxicity. We describe a new algorithm combining random walk-based image segmentation with linear discriminant analysis (LDA)-based feature detection, using assumptions about the morphology of biological samples to account for phase ambiguities when standard methods have failed. We present three versions of our method: first, a method for LDA image segmentation based on a manually compiled training dataset; second, a method using a random walker (RW) algorithm informed by the assumed properties of a biological phase image; and third, an algorithm which combines LDA-based edge detection with an efficient RW algorithm. We show that the combination of LDA plus the RW algorithm gives the best overall performance with little speed penalty compared to LDA alone, and that this algorithm can be further optimized using a genetic algorithm to yield superior performance for phase unwrapping of QPI data from biological samples.

  13. Use of protein: creatinine ratio in a random spot urine sample for predicting significant proteinuria in diabetes mellitus.

    Science.gov (United States)

    Yadav, B K; Adhikari, S; Gyawali, P; Shrestha, R; Poudel, B; Khanal, M

    2010-06-01

    Present study was undertaken during a period of 6 months (September 2008-February 2009) to see an correlation of 24 hours urine protein estimation with random spot protein-creatinine (P:C) ratio among a diabetic patients. The study comprised of 144 patients aged 30-70 years, recruited from Kantipur hospital, Kathmandu. The 24-hr urine sample was collected, followed by spot random urine sample. Both samples were analyzed for protein and creatinine excretion. An informed consent was taken from all participants. Sixteen inadequately collected urine samples as defined by (predicted creatinine--measured creatinine)/predicted creatinine > 0.2 were excluded from analysis. The Spearman's rank correlation between the spot urine P:C ratio and 24-hr total protein were performed by the Statistical Package for Social Service. At the P:C ratio cutoff of 0.15 and reference method (24-hr urine protein) cutoff of 150 mg/day, the correlation coefficient was found to be 0.892 (p urine collection but the cutoff should be carefully selected for different patients group under different laboratory procedures and settings.

  14. THE RHETORICAL USE OF RANDOM SAMPLING: CRAFTING AND COMMUNICATING THE PUBLIC IMAGE OF POLLS AS A SCIENCE (1935-1948).

    Science.gov (United States)

    Lusinchi, Dominic

    2017-03-01

    The scientific pollsters (Archibald Crossley, George H. Gallup, and Elmo Roper) emerged onto the American news media scene in 1935. Much of what they did in the following years (1935-1948) was to promote both the political and scientific legitimacy of their enterprise. They sought to be recognized as the sole legitimate producers of public opinion. In this essay I examine the, mostly overlooked, rhetorical work deployed by the pollsters to publicize the scientific credentials of their polling activities, and the central role the concept of sampling has had in that pursuit. First, they distanced themselves from the failed straw poll by claiming that their sampling methodology based on quotas was informed by science. Second, although in practice they did not use random sampling, they relied on it rhetorically to derive the symbolic benefits of being associated with the "laws of probability." © 2017 Wiley Periodicals, Inc.

  15. Multivariate Multi-Objective Allocation in Stratified Random Sampling: A Game Theoretic Approach.

    Science.gov (United States)

    Muhammad, Yousaf Shad; Hussain, Ijaz; Shoukry, Alaa Mohamd

    2016-01-01

    We consider the problem of multivariate multi-objective allocation where no or limited information is available within the stratum variance. Results show that a game theoretic approach (based on weighted goal programming) can be applied to sample size allocation problems. We use simulation technique to determine payoff matrix and to solve a minimax game.

  16. The effect of dead time on randomly sampled power spectral estimates

    DEFF Research Database (Denmark)

    Buchhave, Preben; Velte, Clara Marika; George, William K.

    2014-01-01

    consider both the effect on the measured spectrum of a finite sampling time, i.e., a finite time during which the signal is acquired, and a finite dead time, that is a time in which the signal processor is busy evaluating a data point and therefore unable to measure a subsequent data point arriving within...... the dead time delay....

  17. Phase microscopy of technical and biological samples through random phase modulation with a difuser

    DEFF Research Database (Denmark)

    Almoro, Percival; Pedrini, Giancarlo; Gundu, Phanindra Narayan

    2010-01-01

    A technique for phase microscopy using a phase diffuser and a reconstruction algorithm is proposed. A magnified specimen wavefront is projected on the diffuser plane that modulates the wavefront into a speckle field. The speckle patterns at axially displaced planes are sampled and used in an iter...

  18. How precise is the finite sample approximation of the asymptotic distribution of realised variation measures in the presence of jumps?

    DEFF Research Database (Denmark)

    Veraart, Almut

    This paper studies the impact of jumps on volatility estimation and inference based on various realised variation measures such as realised variance, realised multipower variation and truncated realised multipower variation. We review the asymptotic theory of those realised variation measures...... the jump–robust statistics turn out not to be as jump robust as the asymptotic theory would suggest in the presence of a highly active jump process...

  19. Randomized two-way cross-over bioequivalence study of two amoxicillin formulations and inter-ethnicity pharmacokinetic variation in healthy Malay volunteers.

    Science.gov (United States)

    Liew, Kai Bin; Loh, Gabriel Onn Kit; Tan, Yvonne Tze Fung; Peh, Kok Khiang

    2014-09-01

    The objectives of this study were to develop a new deproteinization method to extract amoxicillin from human plasma and evaluate the inter-ethnic variation of amoxicillin pharmacokinetics in healthy Malay volunteers. A single-dose, randomized, fasting, two-period, two-treatment, two-sequence crossover, open-label bioequivalence study was conducted in 18 healthy Malay adult male volunteers, with one week washout period. The drug concentration in the sample was analyzed using high-performance liquid chromatography (UV-vis HPLC). The mean (standard deviation) pharmacokinetic parameter results of Moxilen® were: peak concentration (Cmax ), 6.72 (1.56) µg/mL; area under the concentration-time graph (AUC0-8 ), 17.79 (4.29) µg/mL h; AUC0-∞ , 18.84 (4.62) µg/mL h. Those of YSP Amoxicillin® capsule were: Cmax , 6.69 (1.44) µg/mL; AUC0-8 , 18.69 (3.78) µg/mL h; AUC00-∞ , 19.95 (3.81) µg/mL h. The 90% confidence intervals for the logarithmic transformed Cmax , AUC0-8 and AUC0-∞ of Moxilen® vs YSP Amoxicillin® capsule was between 0.80 and 1.25. Both Cmax and AUC met the predetermined criteria for assuming bioequivalence. Both formulations were well tolerated. The results showed significant inter-ethnicity variation in pharmacokinetics of amoxicillin. The Cmax and AUC of amoxicillin in Malay population were slightly lower compared with other populations. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Random Evolutionary Dynamics Driven by Fitness and House-of-Cards Mutations: Sampling Formulae

    Science.gov (United States)

    Huillet, Thierry E.

    2017-07-01

    We first revisit the multi-allelic mutation-fitness balance problem, especially when mutations obey a house of cards condition, where the discrete-time deterministic evolutionary dynamics of the allelic frequencies derives from a Shahshahani potential. We then consider multi-allelic Wright-Fisher stochastic models whose deviation to neutrality is from the Shahshahani mutation/selection potential. We next focus on the weak selection, weak mutation cases and, making use of a Gamma calculus, we compute the normalizing partition functions of the invariant probability densities appearing in their Wright-Fisher diffusive approximations. Using these results, generalized Ewens sampling formulae (ESF) from the equilibrium distributions are derived. We start treating the ESF in the mixed mutation/selection potential case and then we restrict ourselves to the ESF in the simpler house-of-cards mutations only situation. We also address some issues concerning sampling problems from infinitely-many alleles weak limits.

  1. Dual to Ratio-Cum-Product Estimator in Simple and Stratified Random Sampling

    OpenAIRE

    Yunusa Olufadi

    2013-01-01

    New estimators for estimating the finite population mean using two auxiliary variables under simple and stratified sampling design is proposed. Their properties (e.g., mean square error) are studied to the first order of approximation. More so, some estimators are shown to be a particular member of this estimator. Furthermore, comparison of the proposed estimator with the usual unbiased estimator and other estimators considered in this paper reveals interesting results. These results are fur...

  2. The psychometric properties of the AUDIT: a survey from a random sample of elderly Swedish adults.

    Science.gov (United States)

    Källmén, Håkan; Wennberg, Peter; Ramstedt, Mats; Hallgren, Mats

    2014-07-01

    Increasing alcohol consumption and related harms have been reported among the elderly population of Europe. Consequently, it is important to monitor patterns of alcohol use, and to use a valid and reliable tool when screening for risky consumption in this age group. The aim was to evaluate the internal consistency reliability and construct validity of the Alcohol Use Disorders Identification Test (AUDIT) in elderly Swedish adults, and to compare the results with the general Swedish population. Another aim was to calculate the level of alcohol consumption (AUDIT-C) to be used for comparison in future studies. The questionnaire was sent to 1459 Swedish adults aged 79-80 years with a response rate of 73.3%. Internal consistency reliability, were assessed using Cronbach alpha, and confirmatory factor analysis assessed construct validity of the Alcohol Use Disorders Identification Test (AUDIT) in elderly population as compared to a Swedish general population sample. The results showed that AUDIT was more reliable and valid among the Swedish general population sample than among the elderly and that Item 1 and 4 in AUDIT was less reliable and valid among the elderly. While the AUDIT showed acceptable psychometric properties in the general population sample, it's performance was of less quality among the elderly respondents. Further psychometric assessments of the AUDIT in elderly populations are required before it is implemented more widely.

  3. Active Learning Not Associated with Student Learning in a Random Sample of College Biology Courses

    Science.gov (United States)

    Andrews, T. M.; Leonard, M. J.; Colgrove, C. A.; Kalinowski, S. T.

    2011-01-01

    Previous research has suggested that adding active learning to traditional college science lectures substantially improves student learning. However, this research predominantly studied courses taught by science education researchers, who are likely to have exceptional teaching expertise. The present study investigated introductory biology courses randomly selected from a list of prominent colleges and universities to include instructors representing a broader population. We examined the relationship between active learning and student learning in the subject area of natural selection. We found no association between student learning gains and the use of active-learning instruction. Although active learning has the potential to substantially improve student learning, this research suggests that active learning, as used by typical college biology instructors, is not associated with greater learning gains. We contend that most instructors lack the rich and nuanced understanding of teaching and learning that science education researchers have developed. Therefore, active learning as designed and implemented by typical college biology instructors may superficially resemble active learning used by education researchers, but lacks the constructivist elements necessary for improving learning. PMID:22135373

  4. Molecular carbon isotope variations in core samples taken at the Permian-Triassic boundary layers in southern China

    Science.gov (United States)

    Wang, Ruiliang; Zhang, Shuichang; Brassell, Simon; Wang, Jiaxue; Lu, Zhengyuan; Ming, Qingzhong; Wang, Xiaomei; Bian, Lizeng

    2012-07-01

    Stable carbon isotope composition (δ13C) of carbonate sediments and the molecular (biomarker) characteristics of a continuous Permian-Triassic (PT) layer in southern China were studied to obtain geochemical signals of global change at the Permian-Triassic boundary (PTB). Carbonate carbon isotope values shifted toward positive before the end of the Permian period and then shifted negative above the PTB into the Triassic period. Molecular carbon isotope values of biomarkers followed the same trend at and below the PTB and remained negative in the Triassic layer. These biomarkers were acyclic isoprenoids, ranging from C15 to C40, steranes (C27 dominates) and terpenoids that were all significantly more abundant in samples from the Permian layer than those from the Triassic layer. The Triassic layer was distinguished by the dominance of higher molecular weight (waxy) n-alkanes. Stable carbon isotope values of individual components, including n-alkanes and acyclic isoprenoids such as phytane, isop-C25, and squalane, are depleted in δ13C by up to 8-10‰ in the Triassic samples as compared to the Permian. Measured molecular and isotopic variations of organic matter in the PT layers support the generally accepted view of Permian oceanic stagnation followed by a massive upwelling of toxic deep waters at the PTB. A series of large-scale (global) outgassing events may be associated with the carbon isotope shift we measured. This is also consistent with the lithological evidence we observed of white thin-clay layers in this region. Our findings, in context with a generally accepted stagnant Permian ocean, followed by massive upwelling of toxic deep waters might be the major causes of the largest global mass extinction event that occurred at the Permian-Triassic boundary.

  5. Fasting time and lipid parameters: association with hepatic steatosis — data from a random population sample

    Science.gov (United States)

    2014-01-01

    Background Current guidelines recommend measuring plasma lipids in fasting patients. Recent studies, however, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). A second objective was to determine the effect of non-alcoholic fatty liver disease exerted on the above-mentioned lipid levels. Method Subjects participating in a population-based cross-sectional study (2,445 subjects; 51.7% females) were questioned at time of phlebotomy regarding duration of pre-phlebotomy fasting. Total cholesterol, LDL and HDL cholesterol, and triglycerides were determined and correlated with length of fasting. An upper abdominal ultrasonographic examination was performed and body-mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Subjects were divided into three groups based on their reported fasting periods of 1–4 h, 4–8 h and > 8 h. After application of the exclusion criteria, a total of 1,195 subjects (52.4% females) were included in the study collective. The Kruskal-Wallis test was used for continuous variables and the chi-square test for categorical variables. The effects of age, BMI, WHR, alcohol consumption, fasting time and hepatic steatosis on the respective lipid variables were analyzed using multivariate logistic regression. Results At multivariate analysis, fasting time was associated with elevated triglycerides (p = 0.0047 for 1–4 h and p = 0.0147 for 4–8 h among females; p fasting period. LDL cholesterol and triglycerides exhibit highly significant variability; the greatest impact is seen with the triglycerides. Fasting time represents an independent factor for reduced LDL cholesterol and elevated triglyceride concentrations. There is a close association between elevated lipids and hepatic steatosis. PMID:24447492

  6. Fasting time and lipid parameters: association with hepatic steatosis--data from a random population sample.

    Science.gov (United States)

    Gruchot, Martin; Graeter, Tilmann; Oeztuerk, Suemeyra; Haenle, Mark Martin; Koenig, Wolfgang; Imhof, Armin; Boehm, Bernhard Otto; Mason, Richard Andrew; Kratzer, Wolfgang; Akinli, Atilla Serif

    2014-01-22

    Current guidelines recommend measuring plasma lipids in fasting patients. Recent studies, however, suggest that variation in plasma lipid concentrations secondary to fasting time may be minimal. Objective of the present study was to investigate the impact of fasting time on plasma lipid concentrations (total cholesterol, HDL and LDL cholesterol, triglycerides). A second objective was to determine the effect of non-alcoholic fatty liver disease exerted on the above-mentioned lipid levels. Subjects participating in a population-based cross-sectional study (2,445 subjects; 51.7% females) were questioned at time of phlebotomy regarding duration of pre-phlebotomy fasting. Total cholesterol, LDL and HDL cholesterol, and triglycerides were determined and correlated with length of fasting. An upper abdominal ultrasonographic examination was performed and body-mass index (BMI) and waist-to-hip ratio (WHR) were calculated. Subjects were divided into three groups based on their reported fasting periods of 1-4 h, 4-8 h and > 8 h. After application of the exclusion criteria, a total of 1,195 subjects (52.4% females) were included in the study collective. The Kruskal-Wallis test was used for continuous variables and the chi-square test for categorical variables. The effects of age, BMI, WHR, alcohol consumption, fasting time and hepatic steatosis on the respective lipid variables were analyzed using multivariate logistic regression. At multivariate analysis, fasting time was associated with elevated triglycerides (p = 0.0047 for 1-4 h and p = 0.0147 for 4-8 h among females; p fasting period. LDL cholesterol and triglycerides exhibit highly significant variability; the greatest impact is seen with the triglycerides. Fasting time represents an independent factor for reduced LDL cholesterol and elevated triglyceride concentrations. There is a close association between elevated lipids and hepatic steatosis.

  7. Effect of the Mediterranean diet on heart failure biomarkers: a randomized sample from the PREDIMED trial.

    Science.gov (United States)

    Fitó, Montserrat; Estruch, Ramón; Salas-Salvadó, Jordi; Martínez-Gonzalez, Miguel Angel; Arós, Fernando; Vila, Joan; Corella, Dolores; Díaz, Oscar; Sáez, Guillermo; de la Torre, Rafael; Mitjavila, María-Teresa; Muñoz, Miguel Angel; Lamuela-Raventós, Rosa-María; Ruiz-Gutierrez, Valentina; Fiol, Miquel; Gómez-Gracia, Enrique; Lapetra, José; Ros, Emilio; Serra-Majem, Lluis; Covas, María-Isabel

    2014-05-01

    Scarce data are available on the effect of the traditional Mediterranean diet (TMD) on heart failure biomarkers. We assessed the effect of TMD on biomarkers related to heart failure in a high cardiovascular disease risk population. A total of 930 subjects at high cardiovascular risk (420 men and 510 women) were recruited in the framework of a multicentre, randomized, controlled, parallel-group clinical trial directed at testing the efficacy of the TMD on the primary prevention of cardiovascular disease (The PREDIMED Study). Participants were assigned to a low-fat diet (control, n = 310) or one of two TMDs [TMD + virgin olive oil (VOO) or TMD + nuts]. Depending on group assignment, participants received free provision of extra-virgin olive oil, mixed nuts, or small non-food gifts. After 1 year of intervention, both TMDs decreased plasma N-terminal pro-brain natriuretic peptide, with changes reaching significance vs. control group (P cardiovascular disease (CVD) who improved their diet toward a TMD pattern reduced their N-terminal pro-brain natriuretic peptide compared with those assigned to a low-fat diet. The same was found for in vivo oxidized low-density lipoprotein and lipoprotein(a) plasma concentrations after the TMD + VOO diet. From our results TMD could be a useful tool to mitigate against risk factors for heart failure. From our results TMD could modify markers of heart failure towards a more protective mode. © 2014 The Authors. European Journal of Heart Failure © 2014 European Society of Cardiology.

  8. Sequential sampling model for multiattribute choice alternatives with random attention time and processing order.

    Science.gov (United States)

    Diederich, Adele; Oswald, Peter

    2014-01-01

    A sequential sampling model for multiattribute binary choice options, called multiattribute attention switching (MAAS) model, assumes a separate sampling process for each attribute. During the deliberation process attention switches from one attribute consideration to the next. The order in which attributes are considered as well for how long each attribute is considered-the attention time-influences the predicted choice probabilities and choice response times. Several probability distributions for the attention time with different variances are investigated. Depending on the time and order schedule the model predicts a rich choice probability/choice response time pattern including preference reversals and fast errors. Furthermore, the difference between finite and infinite decision horizons for the attribute considered last is investigated. For the former case the model predicts a probability p 0 > 0 of not deciding within the available time. The underlying stochastic process for each attribute is an Ornstein-Uhlenbeck process approximated by a discrete birth-death process. All predictions are also true for the widely applied Wiener process.

  9. Sequential sampling model for multiattribute choice alternatives with random attention time and processing order

    Directory of Open Access Journals (Sweden)

    Adele eDiederich

    2014-09-01

    Full Text Available A sequential sampling model for multiattribute binary choice options, called Multiattribute attention switching (MAAS model, assumes a separate sampling process for each attribute. During the deliberation process attention switches from one attribute consideration to the next. The order in which attributes are considered as well for how long each attribute is considered - the attention time - influences the predicted choice probabilities and choice response times. Several probability distributions for the attention time including deterministic, Poisson, binomial, geometric, and uniform with different variances are investigated. Depending on the time and order schedule the model predicts a rich choice probability/choice response time pattern including preference reversals and fast errors. Furthermore, the difference between a finite and infinite decision horizons for the attribute considered last is investigated. For the former case the model predicts a probability $p_0> 0$ of not deciding within the available time. The underlying stochastic process for each attribute is an Ornstein-Uhlenbeck process approximated by a discrete birth-death process. All predictions are also true for the widely applied Wiener process.

  10. Incorporating covariance estimation uncertainty in spatial sampling design for prediction with trans-Gaussian random fields

    Directory of Open Access Journals (Sweden)

    Gunter eSpöck

    2015-05-01

    Full Text Available Recently, Spock and Pilz [38], demonstratedthat the spatial sampling design problem forthe Bayesian linear kriging predictor can betransformed to an equivalent experimentaldesign problem for a linear regression modelwith stochastic regression coefficients anduncorrelated errors. The stochastic regressioncoefficients derive from the polar spectralapproximation of the residual process. Thus,standard optimal convex experimental designtheory can be used to calculate optimal spatialsampling designs. The design functionals ̈considered in Spock and Pilz [38] did nottake into account the fact that kriging isactually a plug-in predictor which uses theestimated covariance function. The resultingoptimal designs were close to space-fillingconfigurations, because the design criteriondid not consider the uncertainty of thecovariance function.In this paper we also assume that thecovariance function is estimated, e.g., byrestricted maximum likelihood (REML. Wethen develop a design criterion that fully takesaccount of the covariance uncertainty. Theresulting designs are less regular and space-filling compared to those ignoring covarianceuncertainty. The new designs, however, alsorequire some closely spaced samples in orderto improve the estimate of the covariancefunction. We also relax the assumption ofGaussian observations and assume that thedata is transformed to Gaussianity by meansof the Box-Cox transformation. The resultingprediction method is known as trans-Gaussiankriging. We apply the Smith and Zhu [37]approach to this kriging method and show thatresulting optimal designs also depend on theavailable data. We illustrate our results witha data set of monthly rainfall measurementsfrom Upper Austria.

  11. Generalized SAMPLE SIZE Determination Formulas for Investigating Contextual Effects by a Three-Level Random Intercept Model.

    Science.gov (United States)

    Usami, Satoshi

    2017-03-01

    Behavioral and psychological researchers have shown strong interests in investigating contextual effects (i.e., the influences of combinations of individual- and group-level predictors on individual-level outcomes). The present research provides generalized formulas for determining the sample size needed in investigating contextual effects according to the desired level of statistical power as well as width of confidence interval. These formulas are derived within a three-level random intercept model that includes one predictor/contextual variable at each level to simultaneously cover various kinds of contextual effects that researchers can show interest. The relative influences of indices included in the formulas on the standard errors of contextual effects estimates are investigated with the aim of further simplifying sample size determination procedures. In addition, simulation studies are performed to investigate finite sample behavior of calculated statistical power, showing that estimated sample sizes based on derived formulas can be both positively and negatively biased due to complex effects of unreliability of contextual variables, multicollinearity, and violation of assumption regarding the known variances. Thus, it is advisable to compare estimated sample sizes under various specifications of indices and to evaluate its potential bias, as illustrated in the example.

  12. The impact of the introduction of liquid based cytology on the variation in the proportion of inadequate samples between GP practices

    Directory of Open Access Journals (Sweden)

    Jones Suzanne P

    2007-08-01

    Full Text Available Abstract Background Historically there has been a wide variation in the proportion of inadequate smears between general practices. Cervical screening in the UK is undergoing a fundamental change by moving from conventional to liquid based cytology (LBC. The main driver for this change has been a predicted reduction in the proportions of inadequate samples. This study investigates the effect of LBC on the variation in the proportion of inadequate samples between general practices using Shewhart's theory of variation and control charts. Methods Routinely collected cervical cytology data was obtained for all general practices in two localities in South Staffordshire for periods before and after the introduction of liquid based cytology. Control charts of the proportion of inadequate smears were plotted for the practices stratified by laboratory. A standardised measure of variation for all of the practices in each laboratory and each time period was also calculated. Results Following the introduction of liquid based cytology the overall proportion of inadequate samples in the two localities fell from 11.8 to 1.3% (p Conclusion A reduction in the proportion of inadequate samples has been realised in these localities. The reduction in the overall proportion of inadequate samples has also been accompanied by a reduction in variation between GP practices.

  13. Comparison of Detrusor Muscle Sampling Rate in Monopolar and Bipolar Transurethral Resection of Bladder Tumor: A Randomized Trial.

    Science.gov (United States)

    Teoh, Jeremy Yuen-Chun; Chan, Eddie Shu-Yin; Yip, Siu-Ying; Tam, Ho-Man; Chiu, Peter Ka-Fung; Yee, Chi-Hang; Wong, Hon-Ming; Chan, Chi-Kwok; Hou, Simon See-Ming; Ng, Chi-Fai

    2017-05-01

    Our aim was to investigate the detrusor muscle sampling rate after monopolar versus bipolar transurethral resection of bladder tumor (TURBT). This was a single-center, prospective, randomized, phase III trial on monopolar versus bipolar TURBT. Baseline patient characteristics, disease characteristics and perioperative outcomes were compared, with the primary outcome being the detrusor muscle sampling rate in the TURBT specimen. Multivariate logistic regression analyses on detrusor muscle sampling were performed. From May 2012 to December 2015, a total of 160 patients with similar baseline characteristics were randomized to receive monopolar or bipolar TURBT. Fewer patients in the bipolar TURBT group required postoperative irrigation than patients in the monopolar TURBT group (18.7 vs. 43%; p = 0.001). In the whole cohort, no significant difference in the detrusor muscle sampling rates was observed between the bipolar and monopolar TURBT groups (77.3 vs. 63.3%; p = 0.057). In patients with urothelial carcinoma, bipolar TURBT achieved a higher detrusor muscle sampling rate than monopolar TURBT (84.6 vs. 67.7%; p = 0.025). On multivariate analyses, bipolar TURBT (odds ratio [OR] 2.23, 95% confidence interval [CI] 1.03-4.81; p = 0.042) and larger tumor size (OR 1.04, 95% CI 1.01-1.08; p = 0.022) were significantly associated with detrusor muscle sampling in the whole cohort. In addition, bipolar TURBT (OR 2.88, 95% CI 1.10-7.53; p = 0.031), larger tumor size (OR 1.05, 95% CI 1.01-1.10; p = 0.035), and female sex (OR 3.25, 95% CI 1.10-9.59; p = 0.033) were significantly associated with detrusor muscle sampling in patients with urothelial carcinoma. There was a trend towards a superior detrusor muscle sampling rate after bipolar TURBT. Further studies are needed to determine its implications on disease recurrence and progression.

  14. Determining optimal sample sizes for multistage adaptive randomized clinical trials from an industry perspective using value of information methods.

    Science.gov (United States)

    Chen, Maggie H; Willan, Andrew R

    2013-02-01

    Most often, sample size determinations for randomized clinical trials are based on frequentist approaches that depend on somewhat arbitrarily chosen factors, such as type I and II error probabilities and the smallest clinically important difference. As an alternative, many authors have proposed decision-theoretic (full Bayesian) approaches, often referred to as value of information methods that attempt to determine the sample size that maximizes the difference between the trial's expected utility and its expected cost, referred to as the expected net gain. Taking an industry perspective, Willan proposes a solution in which the trial's utility is the increase in expected profit. Furthermore, Willan and Kowgier, taking a societal perspective, show that multistage designs can increase expected net gain. The purpose of this article is to determine the optimal sample size using value of information methods for industry-based, multistage adaptive randomized clinical trials, and to demonstrate the increase in expected net gain realized. At the end of each stage, the trial's sponsor must decide between three actions: continue to the next stage, stop the trial and seek regulatory approval, or stop the trial and abandon the drug. A model for expected total profit is proposed that includes consideration of per-patient profit, disease incidence, time horizon, trial duration, market share, and the relationship between trial results and probability of regulatory approval. The proposed method is extended to include multistage designs with a solution provided for a two-stage design. An example is given. Significant increases in the expected net gain are realized by using multistage designs. The complexity of the solutions increases with the number of stages, although far simpler near-optimal solutions exist. The method relies on the central limit theorem, assuming that the sample size is sufficiently large so that the relevant statistics are normally distributed. From a value of

  15. Uncertainty Of Stream Nutrient Transport Estimates Using Random Sampling Of Storm Events From High Resolution Water Quality And Discharge Data

    Science.gov (United States)

    Scholefield, P. A.; Arnscheidt, J.; Jordan, P.; Beven, K.; Heathwaite, L.

    2007-12-01

    The uncertainties associated with stream nutrient transport estimates are frequently overlooked and the sampling strategy is rarely if ever investigated. Indeed, the impact of sampling strategy and estimation method on the bias and precision of stream phosphorus (P) transport calculations is little understood despite the use of such values in the calibration and testing of models of phosphorus transport. The objectives of this research were to investigate the variability and uncertainty in the estimates of total phosphorus transfers at an intensively monitored agricultural catchment. The Oona Water which is located in the Irish border region, is part of a long term monitoring program focusing on water quality. The Oona Water is a rural river catchment with grassland agriculture and scattered dwelling houses and has been monitored for total phosphorus (TP) at 10 min resolution for several years (Jordan et al, 2007). Concurrent sensitive measurements of discharge are also collected. The water quality and discharge data were provided at 1 hour resolution (averaged) and this meant that a robust estimate of the annual flow weighted concentration could be obtained by simple interpolation between points. A two-strata approach (Kronvang and Bruhn, 1996) was used to estimate flow weighted concentrations using randomly sampled storm events from the 400 identified within the time series and also base flow concentrations. Using a random stratified sampling approach for the selection of events, a series ranging from 10 through to the full 400 were used, each time generating a flow weighted mean using a load-discharge relationship identified through log-log regression and monte-carlo simulation. These values were then compared to the observed total phosphorus concentration for the catchment. Analysis of these results show the impact of sampling strategy, the inherent bias in any estimate of phosphorus concentrations and the uncertainty associated with such estimates. The

  16. Global Stratigraphy of Venus: Analysis of a Random Sample of Thirty-Six Test Areas

    Science.gov (United States)

    Basilevsky, Alexander T.; Head, James W., III

    1995-01-01

    The age relations between 36 impact craters with dark paraboloids and other geologic units and structures at these localities have been studied through photogeologic analysis of Magellan SAR images of the surface of Venus. Geologic settings in all 36 sites, about 1000 x 1000 km each, could be characterized using only 10 different terrain units and six types of structures. These units and structures form a major stratigraphic and geologic sequence (from oldest to youngest): (1) tessera terrain; (2) densely fractured terrains associated with coronae and in the form of remnants among plains; (3) fractured and ridged plains and ridge belts; (4) plains with wrinkle ridges; (5) ridges associated with coronae annulae and ridges of arachnoid annulae which are contemporary with wrinkle ridges of the ridged plains; (6) smooth and lobate plains; (7) fractures of coronae annulae, and fractures not related to coronae annulae, which disrupt ridged and smooth plains; (8) rift-associated fractures; and (9) craters with associated dark paraboloids, which represent the youngest 1O% of the Venus impact crater population (Campbell et al.), and are on top of all volcanic and tectonic units except the youngest episodes of rift-associated fracturing and volcanism; surficial streaks and patches are approximately contemporary with dark-paraboloid craters. Mapping of such units and structures in 36 randomly distributed large regions (each approximately 10(exp 6) sq km) shows evidence for a distinctive regional and global stratigraphic and geologic sequence. On the basis of this sequence we have developed a model that illustrates several major themes in the history of Venus. Most of the history of Venus (that of its first 80% or so) is not preserved in the surface geomorphological record. The major deformation associated with tessera formation in the period sometime between 0.5-1.0 b.y. ago (Ivanov and Basilevsky) is the earliest event detected. In the terminal stages of tessera fon

  17. Use of pornography in a random sample of Norwegian heterosexual couples.

    Science.gov (United States)

    Daneback, Kristian; Traeen, Bente; Månsson, Sven-Axel

    2009-10-01

    This study examined the use of pornography in couple relationships to enhance the sex-life. The study contained a representative sample of 398 heterosexual couples aged 22-67 years. Data collection was carried out by self-administered postal questionnaires. The majority (77%) of the couples did not report any kind of pornography use to enhance the sex-life. In 15% of the couples, both had used pornography; in 3% of the couples, only the female partner had used pornography; and, in 5% of the couples, only the male partner had used pornography for this purpose. Based on the results of a discriminant function analysis, it is suggested that couples where one or both used pornography had a more permissive erotic climate compared to the couples who did not use pornography. In couples where only one partner used pornography, we found more problems related to arousal (male) and negative (female) self-perception. These findings could be of importance for clinicians who work with couples.

  18. Estimating screening-mammography receiver operating characteristic (ROC) curves from stratified random samples of screening mammograms: a simulation study.

    Science.gov (United States)

    Zur, Richard M; Pesce, Lorenzo L; Jiang, Yulei

    2015-05-01

    To evaluate stratified random sampling (SRS) of screening mammograms by (1) Breast Imaging Reporting and Data System (BI-RADS) assessment categories, and (2) the presence of breast cancer in mammograms, for estimation of screening-mammography receiver operating characteristic (ROC) curves in retrospective observer studies. We compared observer study case sets constructed by (1) random sampling (RS); (2) SRS with proportional allocation (SRS-P) with BI-RADS 1 and 2 noncancer cases accounting for 90.6% of all noncancer cases; (3) SRS with disproportional allocation (SRS-D) with BI-RADS 1 and 2 noncancer cases accounting for 10%-80%; and (4) SRS-D and multiple imputation (SRS-D + MI) with missing BI-RADS 1 and 2 noncancer cases imputed to recover the 90.6% proportion. Monte Carlo simulated case sets were drawn from a large case population modeled after published Digital Mammography Imaging Screening Trial data. We compared the bias, root-mean-square error, and coverage of 95% confidence intervals of area under the ROC curve (AUC) estimates from the sampling methods (200-2000 cases, of which 25% were cancer cases) versus from the large case population. AUC estimates were unbiased from RS, SRS-P, and SRS-D + MI, but biased from SRS-D. AUC estimates from SRS-P and SRS-D + MI had 10% smaller root-mean-square error than RS. Both SRS-P and SRS-D + MI can be used to obtain unbiased and 10% more efficient estimate of screening-mammography ROC curves. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  19. Resistência do solo à penetração em resposta ao número de amostras e tipo de amostragem Variation in soil penetration resistance in response to sample number and sampling type

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    João Tavares Filho

    2008-04-01

    com o sistema de manejo e a profundidade de amostragem. A melhor representatividade da média dos resultados de resistência do solo à penetração ocorreu para n > 15 (PD e CP ou n > 20 (0-0,10 m e 15 (0,20-0,60 m no caso do PC. A população amostral n > 10 na profundidade 0-0,60 m, nos dois tipos de amostragem e manejos de solo, permitiu alta exatidão dos dados, tornando os parâmetros estatísticos mais confiáveis, com homogeneidade nos resultados e linearidade apresentada nas curvas das populações amostrais a partir do erro amostral de 10 %Monitoring the state of soil compaction periodically by assessing soil penetration resistance is a practical way of evaluating the effects of different management systems on the soil structure and crop root development. This study aimed to evaluate the variation of soil penetration resistance in response to the number of replications (sample population of different field sampling forms of an Oxisol under three management types: non-tillage (PD, perennial crop (CP and conventional tillage (PC. The experiment was carried out in the Northern Paraná State, Brazil. Samples were collected in three sub-areas of 1ha to determine soil penetration resistance at different depths (0-0.10; 0.10-0.20; 0.20-0.40; 0.40-0.60 m. Sampling was carried out as follows: systematic sampling (grid points, spaced 25 m apart and completely randomized sampling, with 1, 3, 5, 10, 15, 20, 30, 40, and 50 replications. For all points and depths it was determined the average value of penetration resistance (MPa, the confidence interval and estimation accuracy (D of the penetrometer measurements through classical statistical theory based on the number of samples (n and standard deviation of the sample (S, at a significance level of 0.05. For the given experimental conditions (sub-areas of 1ha Oxisol under three different managements, results indicated that the number of representative samples to determine soil penetration resistance did not vary

  20. Randomized Comparison of Two Vaginal Self-Sampling Methods for Human Papillomavirus Detection: Dry Swab versus FTA Cartridge.

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    Rosa Catarino

    Full Text Available Human papillomavirus (HPV self-sampling (self-HPV is valuable in cervical cancer screening. HPV testing is usually performed on physician-collected cervical smears stored in liquid-based medium. Dry filters and swabs are an alternative. We evaluated the adequacy of self-HPV using two dry storage and transport devices, the FTA cartridge and swab.A total of 130 women performed two consecutive self-HPV samples. Randomization determined which of the two tests was performed first: self-HPV using dry swabs (s-DRY or vaginal specimen collection using a cytobrush applied to an FTA cartridge (s-FTA. After self-HPV, a physician collected a cervical sample using liquid-based medium (Dr-WET. HPV types were identified by real-time PCR. Agreement between collection methods was measured using the kappa statistic.HPV prevalence for high-risk types was 62.3% (95%CI: 53.7-70.2 detected by s-DRY, 56.2% (95%CI: 47.6-64.4 by Dr-WET, and 54.6% (95%CI: 46.1-62.9 by s-FTA. There was overall agreement of 70.8% between s-FTA and s-DRY samples (kappa = 0.34, and of 82.3% between self-HPV and Dr-WET samples (kappa = 0.56. Detection sensitivities for low-grade squamous intraepithelial lesion or worse (LSIL+ were: 64.0% (95%CI: 44.5-79.8 for s-FTA, 84.6% (95%CI: 66.5-93.9 for s-DRY, and 76.9% (95%CI: 58.0-89.0 for Dr-WET. The preferred self-collection method among patients was s-DRY (40.8% vs. 15.4%. Regarding costs, FTA card was five times more expensive than the swab (~5 US dollars (USD/per card vs. ~1 USD/per swab.Self-HPV using dry swabs is sensitive for detecting LSIL+ and less expensive than s-FTA.International Standard Randomized Controlled Trial Number (ISRCTN: 43310942.

  1. Optimal Subset Selection of Time-Series MODIS Images and Sample Data Transfer with Random Forests for Supervised Classification Modelling

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    Fuqun Zhou

    2016-10-01

    Full Text Available Nowadays, various time-series Earth Observation data with multiple bands are freely available, such as Moderate Resolution Imaging Spectroradiometer (MODIS datasets including 8-day composites from NASA, and 10-day composites from the Canada Centre for Remote Sensing (CCRS. It is challenging to efficiently use these time-series MODIS datasets for long-term environmental monitoring due to their vast volume and information redundancy. This challenge will be greater when Sentinel 2–3 data become available. Another challenge that researchers face is the lack of in-situ data for supervised modelling, especially for time-series data analysis. In this study, we attempt to tackle the two important issues with a case study of land cover mapping using CCRS 10-day MODIS composites with the help of Random Forests’ features: variable importance, outlier identification. The variable importance feature is used to analyze and select optimal subsets of time-series MODIS imagery for efficient land cover mapping, and the outlier identification feature is utilized for transferring sample data available from one year to an adjacent year for supervised classification modelling. The results of the case study of agricultural land cover classification at a regional scale show that using only about a half of the variables we can achieve land cover classification accuracy close to that generated using the full dataset. The proposed simple but effective solution of sample transferring could make supervised modelling possible for applications lacking sample data.

  2. Optimal Subset Selection of Time-Series MODIS Images and Sample Data Transfer with Random Forests for Supervised Classification Modelling.

    Science.gov (United States)

    Zhou, Fuqun; Zhang, Aining

    2016-10-25

    Nowadays, various time-series Earth Observation data with multiple bands are freely available, such as Moderate Resolution Imaging Spectroradiometer (MODIS) datasets including 8-day composites from NASA, and 10-day composites from the Canada Centre for Remote Sensing (CCRS). It is challenging to efficiently use these time-series MODIS datasets for long-term environmental monitoring due to their vast volume and information redundancy. This challenge will be greater when Sentinel 2-3 data become available. Another challenge that researchers face is the lack of in-situ data for supervised modelling, especially for time-series data analysis. In this study, we attempt to tackle the two important issues with a case study of land cover mapping using CCRS 10-day MODIS composites with the help of Random Forests' features: variable importance, outlier identification. The variable importance feature is used to analyze and select optimal subsets of time-series MODIS imagery for efficient land cover mapping, and the outlier identification feature is utilized for transferring sample data available from one year to an adjacent year for supervised classification modelling. The results of the case study of agricultural land cover classification at a regional scale show that using only about a half of the variables we can achieve land cover classification accuracy close to that generated using the full dataset. The proposed simple but effective solution of sample transferring could make supervised modelling possible for applications lacking sample data.

  3. Media Use and Source Trust among Muslims in Seven Countries: Results of a Large Random Sample Survey

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    Steven R. Corman

    2013-12-01

    Full Text Available Despite the perceived importance of media in the spread of and resistance against Islamist extremism, little is known about how Muslims use different kinds of media to get information about religious issues, and what sources they trust when doing so. This paper reports the results of a large, random sample survey among Muslims in seven countries Southeast Asia, West Africa and Western Europe, which helps fill this gap. Results show a diverse set of profiles of media use and source trust that differ by country, with overall low trust in mediated sources of information. Based on these findings, we conclude that mass media is still the most common source of religious information for Muslims, but that trust in mediated information is low overall. This suggests that media are probably best used to persuade opinion leaders, who will then carry anti-extremist messages through more personal means.

  4. Enhancing positive parent-child interactions and family functioning in a poverty sample: a randomized control trial.

    Science.gov (United States)

    Negrão, Mariana; Pereira, Mariana; Soares, Isabel; Mesman, Judi

    2014-01-01

    This study tested the attachment-based intervention program Video-feedback Intervention to promote Positive Parenting and Sensitive Discipline (VIPP-SD) in a randomized controlled trial with poor families of toddlers screened for professional's concerns about the child's caregiving environment. The VIPP-SD is an evidence-based intervention, but has not yet been tested in the context of poverty. The sample included 43 families with 1- to 4-year-old children: mean age at the pretest was 29 months and 51% were boys. At the pretest and posttest, mother-child interactions were observed at home, and mothers reported on family functioning. The VIPP-SD proved to be effective in enhancing positive parent-child interactions and positive family relations in a severely deprived context. Results are discussed in terms of implications for support services provided to such poor families in order to reduce intergenerational risk transmission.

  5. Rationale, Design, Samples, and Baseline Sun Protection in a Randomized Trial on a Skin Cancer Prevention Intervention in Resort Environments

    Science.gov (United States)

    Buller, David B.; Andersen, Peter A.; Walkosz, Barbara J.; Scott, Michael D.; Beck, Larry; Cutter, Gary R.

    2016-01-01

    Introduction Exposure to solar ultraviolet radiation during recreation is a risk factor for skin cancer. A trial evaluating an intervention to promote advanced sun protection (sunscreen pre-application/reapplication; protective hats and clothing; use of shade) during vacations. Materials and Methods Adult visitors to hotels/resorts with outdoor recreation (i.e., vacationers) participated in a group-randomized pretest-posttest controlled quasi-experimental design in 2012–14. Hotels/resorts were pair-matched and randomly assigned to the intervention or untreated control group. Sun protection (e.g., clothing, hats, shade and sunscreen) was measured in cross-sectional samples by observation and a face-to-face intercept survey during two-day visits. Results Initially, 41 hotel/resorts (11%) participated but 4 dropped out before posttest. Hotel/resorts were diverse (employees=30 to 900; latitude=24o 78′ N to 50o 52′ N; elevation=2 ft. to 9,726 ft. above sea level), and had a variety of outdoor venues (beaches/pools, court/lawn games, golf courses, common areas, and chairlifts). At pretest, 4,347 vacationers were observed and 3,531 surveyed. More females were surveyed (61%) than observed (50%). Vacationers were mostly 35–60 years old, highly educated (college education = 68%) and non-Hispanic white (93%), with high-risk skin types (22%). Vacationers reported covering 60% of their skin with clothing. Also, 40% of vacationers used shade; 60% applied sunscreen; and 42% had been sunburned. Conclusions The trial faced challenges recruiting resorts but result show that the large, multi-state sample of vacationers were at high risk for solar UV exposure. PMID:26593781

  6. Investigating causal associations between use of nicotine, alcohol, caffeine, and cannabis: A two-sample bidirectional Mendelian randomization study.

    Science.gov (United States)

    Verweij, Karin J H; Treur, Jorien L; Vink, Jacqueline M

    2018-01-15

    Epidemiological studies consistently show co-occurrence of use of different addictive substances. Whether these associations are causal or due to overlapping underlying influences remains an important question in addiction research. Methodological advances have made it possible to use published genetic associations to infer causal relationships between phenotypes. In this exploratory study, we used Mendelian randomization (MR) to examine the causality of well-established associations between nicotine, alcohol, caffeine, and cannabis use. Two-sample MR was employed to estimate bi-directional causal effects between four addictive substances: nicotine (smoking initiation and cigarettes smoked per day), caffeine (cups of coffee per day), alcohol (units per week), and cannabis (initiation). Based on existing genome-wide association results we selected genetic variants associated with the exposure measure as an instrument to estimate causal effects. Where possible we applied sensitivity analyses (MR-Egger and weighted median) more robust to horizontal pleiotropy. Most MR tests did not reveal causal associations. There was some weak evidence for a causal positive effect of genetically instrumented alcohol use on smoking initiation and of cigarettes per day on caffeine use, but these did not hold up with the sensitivity analyses. There was also some suggestive evidence for a positive effect of alcohol use on caffeine use (only with MR-Egger) and smoking initiation on cannabis initiation (only with weighted median). None of the suggestive causal associations survived corrections for multiple testing. Two-sample Mendelian randomization analyses found little evidence for causal relationships between nicotine, alcohol, caffeine, and cannabis use. This article is protected by copyright. All rights reserved.

  7. Long-term sampling of CO(2) from waste-to-energy plants: (14)C determination methodology, data variation and uncertainty.

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    Fuglsang, Karsten; Pedersen, Niels Hald; Larsen, Anna Warberg; Astrup, Thomas Fruergaard

    2014-02-01

    A dedicated sampling and measurement method was developed for long-term measurements of biogenic and fossil-derived CO(2) from thermal waste-to-energy processes. Based on long-term sampling of CO(2) and (14)C determination, plant-specific emission factors can be determined more accurately, and the annual emission of fossil CO(2) from waste-to-energy plants can be monitored according to carbon trading schemes and renewable energy certificates. Weekly and monthly measurements were performed at five Danish waste incinerators. Significant variations between fractions of biogenic CO(2) emitted were observed, not only over time, but also between plants. From the results of monthly samples at one plant, the annual mean fraction of biogenic CO(2) was found to be 69% of the total annual CO(2) emissions. From weekly samples, taken every 3 months at the five plants, significant seasonal variations in biogenic CO(2) emissions were observed (between 56% and 71% biogenic CO(2)). These variations confirmed that biomass fractions in the waste can vary considerably, not only from day to day but also from month to month. An uncertainty budget for the measurement method itself showed that the expanded uncertainty of the method was ± 4.0 pmC (95 % confidence interval) at 62 pmC. The long-term sampling method was found to be useful for waste incinerators for determination of annual fossil and biogenic CO(2) emissions with relatively low uncertainty.

  8. Efficacy of micronutrient supplementation on skin aging and seasonal variation: a randomized, placebo-controlled, double-blind study

    Directory of Open Access Journals (Sweden)

    Fanian F

    2013-11-01

    Full Text Available Ferial Fanian,1,2 Sophie Mac-Mary,3 Adeline Jeudy,1,2 Thomas Lihoreau,1,2 Rafat Messikh,1,2 Jean-Paul Ortonne,4 Jean-Marie Sainthillier,3 Ahmed Elkhyat,1,2 Alexandre Guichard,1,2 Kamran Hejazi Kenari,1,2 Philippe Humbert1,2,5,61Center for Studies and Research on the Integument (CERT, Department of Dermatology, University Hospital of Besançon, Besançon, France; 2Clinical Investigation Center, CIC-BT 506, CHRU Besançon, France; 3SKINEXIGENCE, University Hospital of Jean Minjoz, Besançon, France; 4Department of Dermatology, University Hospital of L'archet, Nice, France; 5University of Franche-Comté, Besançon, France; 6INSERM 1098, Structure Fédérative de Recherche, Besançon, FranceBackground: Several studies have confirmed dramatic changes in skin surface parameters during the winter months. Although there are many studies supporting the positive effects of topical treatment, there are no published studies demonstrating the effects of oral supplementation in the prevention of negative skin changes during winter. The purpose of this study was to evaluate the efficacy of an oral micronutrient supplement in preventing the negative effects of winter weather on skin quality using noninvasive biometrologic instruments.Methods: This study included 80 healthy female volunteers aged 35–55 years with phototype II–IV skin. Randomization was balanced. Two tablets of a micronutrient supplement (Perfectil® Platinum or placebo were administered once daily for 4 months. The volunteers were examined at baseline, after 4 months, and 6 weeks after termination of treatment (month 5.5. The evaluation included skin microrelief by Visioscan® as the main outcome, and the secondary outcomes were results on standard macrophotography, skin tension by Reviscometer®, skin high-frequency ultrasound, and self-assessment.Results: For all pseudoroughness and microrelief indicators, there was a significant increase from baseline to month 4 in the placebo group (P<0

  9. GenoSNP: a variational Bayes within-sample SNP genotyping algorithm that does not require a reference population.

    Science.gov (United States)

    Giannoulatou, Eleni; Yau, Christopher; Colella, Stefano; Ragoussis, Jiannis; Holmes, Christopher C

    2008-10-01

    Current genotyping algorithms typically call genotypes by clustering allele-specific intensity data on a single nucleotide polymorphism (SNP) by SNP basis. This approach assumes the availability of a large number of control samples that have been sampled on the same array and platform. We have developed a SNP genotyping algorithm for the Illumina Infinium SNP genotyping assay that is entirely within-sample and does not require the need for a population of control samples nor parameters derived from such a population. Our algorithm exhibits high concordance with current methods and >99% call accuracy on HapMap samples. The ability to call genotypes using only within-sample information makes the method computationally light and practical for studies involving small sample sizes and provides a valuable independent quality control metric for other population-based approaches. http://www.stats.ox.ac.uk/~giannoul/GenoSNP/.

  10. Pre-equilibrium solid-phase microextraction of free analyte in complex samples: correction for mass transfer variation from protein binding and matrix tortuosity.

    Science.gov (United States)

    Zhang, Xu; Oakes, Ken D; Hoque, Md Ehsanul; Luong, Di; Metcalfe, Chris D; Pawliszyn, Janusz; Servos, Mark R

    2011-05-01

    The accurate measurement of free analyte concentrations within complex sample matrixes by pre-equilibrium solid-phase microextraction (SPME) has proven challenging due to variations in mass uptake kinetics. For the first time, the effects of the sample binding matrix and tortuosity on the kinetics of analyte extraction (from the sample to the SPME fiber) are demonstrated to be quantitatively symmetrical with those of the desorption of preloaded deuterated standards (from the fiber to the sample matrix). Consequently, kinetic calibration methods can be employed to correct for variation in SPME sampling kinetics, facilitating the application of pre-equilibrium SPME within complex sample systems. This approach was applied ex vivo to measure pharmaceuticals in fish muscle tissues, with results consistent with those obtained from equilibrium SPME and microdialysis. The developed method has the inherent advantages of being more accurate, precise, and reproducible, thus providing the framework for applications where rapid measurement of free analyte concentrations (within complicated sample matrixes such as biological tissues, sediment, and surface water) are required.

  11. High Field In Vivo 13C Magnetic Resonance Spectroscopy of Brain by Random Radiofrequency Heteronuclear Decoupling and Data Sampling

    Science.gov (United States)

    Li, Ningzhi; Li, Shizhe; Shen, Jun

    2017-06-01

    In vivo 13C magnetic resonance spectroscopy (MRS) is a unique and effective tool for studying dynamic human brain metabolism and the cycling of neurotransmitters. One of the major technical challenges for in vivo 13C-MRS is the high radio frequency (RF) power necessary for heteronuclear decoupling. In the common practice of in vivo 13C-MRS, alkanyl carbons are detected in the spectra range of 10-65ppm. The amplitude of decoupling pulses has to be significantly greater than the large one-bond 1H-13C scalar coupling (1JCH=125-145 Hz). Two main proton decoupling methods have been developed: broadband stochastic decoupling and coherent composite or adiabatic pulse decoupling (e.g., WALTZ); the latter is widely used because of its efficiency and superb performance under inhomogeneous B1 field. Because the RF power required for proton decoupling increases quadratically with field strength, in vivo 13C-MRS using coherent decoupling is often limited to low magnetic fields (Drug Administration (FDA). Alternately, carboxylic/amide carbons are coupled to protons via weak long-range 1H-13C scalar couplings, which can be decoupled using low RF power broadband stochastic decoupling. Recently, the carboxylic/amide 13C-MRS technique using low power random RF heteronuclear decoupling was safely applied to human brain studies at 7T. Here, we review the two major decoupling methods and the carboxylic/amide 13C-MRS with low power decoupling strategy. Further decreases in RF power deposition by frequency-domain windowing and time-domain random under-sampling are also discussed. Low RF power decoupling opens the possibility of performing in vivo 13C experiments of human brain at very high magnetic fields (such as 11.7T), where signal-to-noise ratio as well as spatial and temporal spectral resolution are more favorable than lower fields.

  12. Rationale, design, methodology and sample characteristics for the Vietnam pre-conceptual micronutrient supplementation trial (PRECONCEPT: a randomized controlled study

    Directory of Open Access Journals (Sweden)

    Nguyen Phuong H

    2012-10-01

    Full Text Available Abstract Background Low birth weight and maternal anemia remain intractable problems in many developing countries. The adequacy of the current strategy of providing iron-folic acid (IFA supplements only during pregnancy has been questioned given many women enter pregnancy with poor iron stores, the substantial micronutrient demand by maternal and fetal tissues, and programmatic issues related to timing and coverage of prenatal care. Weekly IFA supplementation for women of reproductive age (WRA improves iron status and reduces the burden of anemia in the short term, but few studies have evaluated subsequent pregnancy and birth outcomes. The Preconcept trial aims to determine whether pre-pregnancy weekly IFA or multiple micronutrient (MM supplementation will improve birth outcomes and maternal and infant iron status compared to the current practice of prenatal IFA supplementation only. This paper provides an overview of study design, methodology and sample characteristics from baseline survey data and key lessons learned. Methods/design We have recruited 5011 WRA in a double-blind stratified randomized controlled trial in rural Vietnam and randomly assigned them to receive weekly supplements containing either: 1 2800 μg folic acid 2 60 mg iron and 2800 μg folic acid or 3 MM. Women who become pregnant receive daily IFA, and are being followed through pregnancy, delivery, and up to three months post-partum. Study outcomes include birth outcomes and maternal and infant iron status. Data are being collected on household characteristics, maternal diet and mental health, anthropometry, infant feeding practices, morbidity and compliance. Discussion The study is timely and responds to the WHO Global Expert Consultation which identified the need to evaluate the long term benefits of weekly IFA and MM supplementation in WRA. Findings will generate new information to help guide policy and programs designed to reduce the burden of anemia in women and

  13. Comparing attitudes about legal sanctions and teratogenic effects for cocaine, alcohol, tobacco and caffeine: A randomized, independent samples design

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    Alanis Kelly L

    2006-02-01

    Full Text Available Abstract Background Establishing more sensible measures to treat cocaine-addicted mothers and their children is essential for improving U.S. drug policy. Favorable post-natal environments have moderated potential deleterious prenatal effects. However, since cocaine is an illicit substance having long been demonized, we hypothesized that attitudes toward prenatal cocaine exposure would be more negative than for licit substances, alcohol, nicotine and caffeine. Further, media portrayals about long-term outcomes were hypothesized to influence viewers' attitudes, measured immediately post-viewing. Reducing popular crack baby stigmas could influence future policy decisions by legislators. In Study 1, 336 participants were randomly assigned to 1 of 4 conditions describing hypothetical legal sanction scenarios for pregnant women using cocaine, alcohol, nicotine or caffeine. Participants rated legal sanctions against pregnant women who used one of these substances and risk potential for developing children. In Study 2, 139 participants were randomly assigned to positive, neutral and negative media conditions. Immediately post-viewing, participants rated prenatal cocaine-exposed or non-exposed teens for their academic performance and risk for problems at age18. Results Participants in Study 1 imposed significantly greater legal sanctions for cocaine, perceiving prenatal cocaine exposure as more harmful than alcohol, nicotine or caffeine. A one-way ANOVA for independent samples showed significant differences, beyond .0001. Post-hoc Sheffe test illustrated that cocaine was rated differently from other substances. In Study 2, a one-way ANOVA for independent samples was performed on difference scores for the positive, neutral or negative media conditions about prenatal cocaine exposure. Participants in the neutral and negative media conditions estimated significantly lower grade point averages and more problems for the teen with prenatal cocaine exposure

  14. Comparing attitudes about legal sanctions and teratogenic effects for cocaine, alcohol, tobacco and caffeine: A randomized, independent samples design

    Science.gov (United States)

    Ginsburg, Harvey J; Raffeld, Paul; Alanis, Kelly L; Boyce, Angela S

    2006-01-01

    Background Establishing more sensible measures to treat cocaine-addicted mothers and their children is essential for improving U.S. drug policy. Favorable post-natal environments have moderated potential deleterious prenatal effects. However, since cocaine is an illicit substance having long been demonized, we hypothesized that attitudes toward prenatal cocaine exposure would be more negative than for licit substances, alcohol, nicotine and caffeine. Further, media portrayals about long-term outcomes were hypothesized to influence viewers' attitudes, measured immediately post-viewing. Reducing popular crack baby stigmas could influence future policy decisions by legislators. In Study 1, 336 participants were randomly assigned to 1 of 4 conditions describing hypothetical legal sanction scenarios for pregnant women using cocaine, alcohol, nicotine or caffeine. Participants rated legal sanctions against pregnant women who used one of these substances and risk potential for developing children. In Study 2, 139 participants were randomly assigned to positive, neutral and negative media conditions. Immediately post-viewing, participants rated prenatal cocaine-exposed or non-exposed teens for their academic performance and risk for problems at age18. Results Participants in Study 1 imposed significantly greater legal sanctions for cocaine, perceiving prenatal cocaine exposure as more harmful than alcohol, nicotine or caffeine. A one-way ANOVA for independent samples showed significant differences, beyond .0001. Post-hoc Sheffe test illustrated that cocaine was rated differently from other substances. In Study 2, a one-way ANOVA for independent samples was performed on difference scores for the positive, neutral or negative media conditions about prenatal cocaine exposure. Participants in the neutral and negative media conditions estimated significantly lower grade point averages and more problems for the teen with prenatal cocaine exposure than for the non-exposed teen

  15. Review of variations in Mw < 7 earthquake motions on position and TEC (Mw = 6.5 Aegean Sea earthquake sample)

    Science.gov (United States)

    Yildirim, Omer; Inyurt, Samed; Mekik, Cetin

    2016-02-01

    Turkey is a country located in the middle latitude zone, where tectonic activity is intensive. Recently, an earthquake of magnitude 6.5 Mw occurred offshore in the Aegean Sea on 24 May 2014 at 09:25 UTC, which lasted about 40 s. The earthquake was also felt in Greece, Romania, and Bulgaria in addition to Turkey. In recent years, ionospheric anomaly detection studies have been carried out because of seismicity with total electron content (TEC) computed from the global navigation satellite system's (GNSS) signal delays and several interesting findings have been published. In this study, both TEC and positional variations have been examined separately following a moderate size earthquake in the Aegean Sea. The correlation of the aforementioned ionospheric variation with the positional variation has also been investigated. For this purpose, a total of 15 stations was used, including four continuously operating reference stations in Turkey (CORS-TR) and stations in the seismic zone (AYVL, CANA, IPSA, and YENC), as well as international GNSS service (IGS) and European reference frame permanent network (EPN) stations. The ionospheric and positional variations of the AYVL, CANA, IPSA, and YENC stations were examined using Bernese v5.0 software. When the precise point positioning TEC (PPP-TEC) values were examined, it was observed that the TEC values were approximately 4 TECU (total electron content unit) above the upper-limit TEC value at four stations located in Turkey, 3 days before the earthquake at 08:00 and 10:00 UTC. At the same stations, on the day before the earthquake at 06:00, 08:00, and 10:00 UTC, the TEC values were approximately 5 TECU below the lower-limit TEC value. The global ionosphere model TEC (GIM-TEC) values published by the Centre for Orbit Determination in Europe (CODE) were also examined. Three days before the earthquake, at all stations, it was observed that the TEC values in the time period between 08:00 and 10:00 UTC were approximately 2 TECU

  16. Association of macronutrient intake patterns with being overweight in a population-based random sample of men in France.

    Science.gov (United States)

    Ahluwalia, N; Ferrières, J; Dallongeville, J; Simon, C; Ducimetière, P; Amouyel, P; Arveiler, D; Ruidavets, J-B

    2009-04-01

    Diet is considered an important modifiable factor in the overweight. The role of macronutrients in obesity has been examined in general in selected populations, but the results of these studies are mixed, depending on the potential confounders and adjustments for other macronutrients. For this reason, we examined the association between macronutrient intake patterns and being overweight in a population-based representative sample of middle-aged (55.1+/-6.1 years) men (n=966), using various adjustment modalities. The study subjects kept 3-day food-intake records, and the standard cardiovascular risk factors were assessed. Weight, height and waist circumference (WC) were also measured. Carbohydrate intake was negatively associated and fat intake was positively associated with body mass index (BMI) and WC in regression models adjusted for energy intake and other factors, including age, smoking and physical activity. However, with mutual adjustments for other energy-yielding nutrients, the negative association of carbohydrate intake with WC remained significant, whereas the associations between fat intake and measures of obesity did not. Adjusted odds ratios (95% confidence interval) comparing the highest and lowest quartiles of carbohydrate intake were 0.50 (0.25-0.97) for obesity (BMI>29.9) and 0.41 (0.23-0.73) for abdominal obesity (WC>101.9 cm). Consistent negative associations between carbohydrate intake and BMI and WC were seen in this random representative sample of the general male population. The associations between fat intake and these measures of being overweight were attenuated on adjusting for carbohydrate intake. Thus, the balance of carbohydrate-to-fat intake is an important element in obesity in a general male population, and should be highlighted in dietary guidelines.

  17. Assessing causality in associations between cannabis use and schizophrenia risk: a two-sample Mendelian randomization study.

    Science.gov (United States)

    Gage, S H; Jones, H J; Burgess, S; Bowden, J; Davey Smith, G; Zammit, S; Munafò, M R

    2017-04-01

    Observational associations between cannabis and schizophrenia are well documented, but ascertaining causation is more challenging. We used Mendelian randomization (MR), utilizing publicly available data as a method for ascertaining causation from observational data. We performed bi-directional two-sample MR using summary-level genome-wide data from the International Cannabis Consortium (ICC) and the Psychiatric Genomics Consortium (PGC2). Single nucleotide polymorphisms (SNPs) associated with cannabis initiation (p schizophrenia (p cannabis initiation on risk of schizophrenia [odds ratio (OR) 1.04 per doubling odds of cannabis initiation, 95% confidence interval (CI) 1.01-1.07, p = 0.019]. There was strong evidence consistent with a causal effect of schizophrenia risk on likelihood of cannabis initiation (OR 1.10 per doubling of the odds of schizophrenia, 95% CI 1.05-1.14, p = 2.64 × 10-5). Findings were as predicted for the negative control (height: OR 1.00, 95% CI 0.99-1.01, p = 0.90) but weaker than predicted for the positive control (years in education: OR 0.99, 95% CI 0.97-1.00, p = 0.066) analyses. Our results provide some that cannabis initiation increases the risk of schizophrenia, although the size of the causal estimate is small. We find stronger evidence that schizophrenia risk predicts cannabis initiation, possibly as genetic instruments for schizophrenia are stronger than for cannabis initiation.

  18. Multiple-image authentication with a cascaded multilevel architecture based on amplitude field random sampling and phase information multiplexing.

    Science.gov (United States)

    Fan, Desheng; Meng, Xiangfeng; Wang, Yurong; Yang, Xiulun; Pan, Xuemei; Peng, Xiang; He, Wenqi; Dong, Guoyan; Chen, Hongyi

    2015-04-10

    A multiple-image authentication method with a cascaded multilevel architecture in the Fresnel domain is proposed, in which a synthetic encoded complex amplitude is first fabricated, and its real amplitude component is generated by iterative amplitude encoding, random sampling, and space multiplexing for the low-level certification images, while the phase component of the synthetic encoded complex amplitude is constructed by iterative phase information encoding and multiplexing for the high-level certification images. Then the synthetic encoded complex amplitude is iteratively encoded into two phase-type ciphertexts located in two different transform planes. During high-level authentication, when the two phase-type ciphertexts and the high-level decryption key are presented to the system and then the Fresnel transform is carried out, a meaningful image with good quality and a high correlation coefficient with the original certification image can be recovered in the output plane. Similar to the procedure of high-level authentication, in the case of low-level authentication with the aid of a low-level decryption key, no significant or meaningful information is retrieved, but it can result in a remarkable peak output in the nonlinear correlation coefficient of the output image and the corresponding original certification image. Therefore, the method realizes different levels of accessibility to the original certification image for different authority levels with the same cascaded multilevel architecture.

  19. Mental health impact of the 2010 Haiti earthquake on the Miami Haitian population: A random-sample survey.

    Science.gov (United States)

    Messiah, Antoine; Acuna, Juan M; Castro, Grettel; de la Vega, Pura Rodríguez; Vaiva, Guillaume; Shultz, James; Neria, Yuval; De La Rosa, Mario

    2014-07-01

    This study examined the mental health consequences of the January 2010 Haiti earthquake on Haitians living in Miami-Dade County, Florida, 2-3 years following the event. A random-sample household survey was conducted from October 2011 through December 2012 in Miami-Dade County, Florida. Haitian participants (N = 421) were assessed for their earthquake exposure and its impact on family, friends, and household finances; and for symptoms of posttraumatic stress disorder (PTSD), anxiety, and major depression; using standardized screening measures and thresholds. Exposure was considered as "direct" if the interviewee was in Haiti during the earthquake. Exposure was classified as "indirect" if the interviewee was not in Haiti during the earthquake but (1) family members or close friends were victims of the earthquake, and/or (2) family members were hosted in the respondent's household, and/or (3) assets or jobs were lost because of the earthquake. Interviewees who did not qualify for either direct or indirect exposure were designated as "lower" exposure. Eight percent of respondents qualified for direct exposure, and 63% qualified for indirect exposure. Among those with direct exposure, 19% exceeded threshold for PTSD, 36% for anxiety, and 45% for depression. Corresponding percentages were 9%, 22% and 24% for respondents with indirect exposure, and 6%, 14%, and 10% for those with lower exposure. A majority of Miami Haitians were directly or indirectly exposed to the earthquake. Mental health distress among them remains considerable two to three years post-earthquake.

  20. Mental Health Impact of Hosting Disaster Refugees: Analyses from a Random Sample Survey Among Haitians Living in Miami.

    Science.gov (United States)

    Messiah, Antoine; Lacoste, Jérôme; Gokalsing, Erick; Shultz, James M; Rodríguez de la Vega, Pura; Castro, Grettel; Acuna, Juan M

    2016-08-01

    Studies on the mental health of families hosting disaster refugees are lacking. This study compares participants in households that hosted 2010 Haitian earthquake disaster refugees with their nonhost counterparts. A random sample survey was conducted from October 2011 through December 2012 in Miami-Dade County, Florida. Haitian participants were assessed regarding their 2010 earthquake exposure and impact on family and friends and whether they hosted earthquake refugees. Using standardized scores and thresholds, they were evaluated for symptoms of three common mental disorders (CMDs): posttraumatic stress disorder, generalized anxiety disorder, and major depressive disorder (MDD). Participants who hosted refugees (n = 51) had significantly higher percentages of scores beyond thresholds for MDD than those who did not host refugees (n = 365) and for at least one CMD, after adjusting for participants' earthquake exposures and effects on family and friends. Hosting refugees from a natural disaster appears to elevate the risk for MDD and possibly other CMDs, independent of risks posed by exposure to the disaster itself. Families hosting refugees deserve special attention.

  1. Randomization modeling to ascertain clustering patterns of human papillomavirus types detected in cervicovaginal samples in the United States.

    Directory of Open Access Journals (Sweden)

    Troy David Querec

    Full Text Available Detection of multiple human papillomavirus (HPV types in the genital tract is common. Associations among HPV types may impact HPV vaccination modeling and type replacement. The objectives were to determine the distribution of concurrent HPV type infections in cervicovaginal samples and examine type-specific associations. We analyzed HPV genotyping results from 32,245 cervicovaginal specimens collected from women aged 11 to 83 years in the United States from 2001 through 2011. Statistical power was enhanced by combining 6 separate studies. Expected concurrent infection frequencies from a series of permutation models, each with increasing fidelity to the real data, were compared with the observed data. Statistics were computed based on the distributional properties of the randomized data. Concurrent detection occurred more than expected with 0 or ≥3 HPV types and less than expected with 1 and 2 types. Some women bear a disproportionate burden of the HPV type prevalence. Type associations were observed that exceeded multiple hypothesis corrected significance. Multiple HPV types were detected more frequently than expected by chance and associations among particular HPV types were detected. However vaccine-targeted types were not specifically affected, supporting the expectation that current bivalent/quadrivalent HPV vaccination will not result in type replacement with other high-risk types.

  2. Sleep quality and body composition variations in obese male adults after 14 weeks of yoga intervention: A randomized controlled trial

    OpenAIRE

    P B Rshikesan; Pailoor Subramanya; Deepeshwar Singh

    2017-01-01

    Background: Obesity is a big challenge all over the world. It is associated with many noncommunicable diseases. Yoga known to be add-on treatment may be effective for obesity control. Aim: To assess the effect of integrated approach of yoga therapy (IAYT) for body composition and quality of sleep in adult obese male. Subjects and Methods: A randomized controlled trial was conducted for 14 weeks on obese male of urban setting. Eighty individuals were randomly divided into two groups, i.e., yog...

  3. Standardization and optimization of core sampling procedure for carbon isotope analysis in eucalyptus and variation in carbon isotope ratios across species and growth conditions

    CSIR Research Space (South Africa)

    Raju, M

    2011-11-01

    Full Text Available and optimization of core sampling procedure for carbon isotope analysis in eucalyptus and variation in carbon isotope ratios across species and growth conditions Mohan Raju, B#; Nuveshen Naidoo*; Sheshshaayee, M. S; Verryn, S. D*; Kamalkannan, R^; Bindumadhava... isotope analysis in Eucalyptus. Methods Expt 1: * Cores were taken from periphery to pith in 5 year old trees of Eucalyptus * Five half sib families of Eucalyptus grandis & E. urophylla were used ? Cores were further subdivided into 5 fragments...

  4. Random within-herd variation in financial performance and time to financial steady-state following management changes in the dairy herd

    DEFF Research Database (Denmark)

    Kristensen, Erling Lundager; Østergaard, Søren; Krogh, Mogens Agerbo

    2008-01-01

    The manager of a dairy herd and the affiliated consultants constantly need to judge whether financial performance of the production system is satisfactory and whether financial performance relates to real (systematic) effects of changes in management. This is no easy task because the dairy herd...... is a very complex system. Thus, it is difficult to obtain empirical data that allows a valid estimation of the random (within-herd) variation in financial performance corrected for management changes. Thus, simulation seems to be the only option. This study suggests that much caution must be recommended...... when claming effect of changes in herd management because the link between management changes (cause) and effect (measured as improvement of gross margin per cow year) is extensively blurred by a large within-herd variation in available real life accounting data and differences between herds in time...

  5. Run charts revisited: a simulation study of run chart rules for detection of non-random variation in health care processes.

    Science.gov (United States)

    Anhøj, Jacob; Olesen, Anne Vingaard

    2014-01-01

    A run chart is a line graph of a measure plotted over time with the median as a horizontal line. The main purpose of the run chart is to identify process improvement or degradation, which may be detected by statistical tests for non-random patterns in the data sequence. We studied the sensitivity to shifts and linear drifts in simulated processes using the shift, crossings and trend rules for detecting non-random variation in run charts. The shift and crossings rules are effective in detecting shifts and drifts in process centre over time while keeping the false signal rate constant around 5% and independent of the number of data points in the chart. The trend rule is virtually useless for detection of linear drift over time, the purpose it was intended for.

  6. Sample collections from healthy volunteers for biological variation estimates' update: a new project undertaken by the Working Group on Biological Variation established by the European Federation of Clinical Chemistry and Laboratory Medicine.

    Science.gov (United States)

    Carobene, Anna; Strollo, Marta; Jonker, Niels; Barla, Gerhard; Bartlett, William A; Sandberg, Sverre; Sylte, Marit Sverresdotter; Røraas, Thomas; Sølvik, Una Ørvim; Fernandez-Calle, Pilar; Díaz-Garzón, Jorge; Tosato, Francesca; Plebani, Mario; Coşkun, Abdurrahman; Serteser, Mustafa; Unsal, Ibrahim; Ceriotti, Ferruccio

    2016-10-01

    Biological variation (BV) data have many fundamental applications in laboratory medicine. At the 1st Strategic Conference of the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) the reliability and limitations of current BV data were discussed. The EFLM Working Group on Biological Variation is working to increase the quality of BV data by developing a European project to establish a biobank of samples from healthy subjects to be used to produce high quality BV data. The project involved six European laboratories (Milan, Italy; Bergen, Norway; Madrid, Spain; Padua, Italy; Istanbul, Turkey; Assen, The Netherlands). Blood samples were collected from 97 volunteers (44 men, aged 20-60 years; 43 women, aged 20-50 years; 10 women, aged 55-69 years). Initial subject inclusion required that participants completed an enrolment questionnaire to verify their health status. The volunteers provided blood specimens once per week for 10 weeks. A short questionnaire was completed and some laboratory tests were performed at each sampling consisting of blood collected under controlled conditions to provide serum, K2EDTA-plasma and citrated-plasma samples. Samples from six out of the 97 enroled subjects were discarded as a consequence of abnormal laboratory measurements. A biobank of 18,000 aliquots was established consisting of 120 aliquots of serum, 40 of EDTA-plasma, and 40 of citrated-plasma from each subject. The samples were stored at -80 °C. A biobank of well-characterised samples collected under controlled conditions has been established delivering a European resource to enable production of contemporary BV data.

  7. [Acupuncture and moxibustion for peripheral facial palsy at different stages: multi-central large-sample randomized controlled trial].

    Science.gov (United States)

    Li, Ying; Li, Yan; Liu, Li-an; Zhao, Ling; Hu, Ka-ming; Wu, Xi; Chen, Xiao-qin; Li, Gui-ping; Mang, Ling-ling; Qi, Qi-hua

    2011-04-01

    To explore the best intervention time of acupuncture and moxibustion for peripheral facial palsy (Bell's palsy) and the clinical advantage program of selective treatment with acupuncture and moxibustion. Multi-central large-sample randomized controlled trial was carried out. Nine hundreds cases of Bell's palsy were randomized into 5 treatment groups, named selective filiform needle group (group A), selective acupuncture + moxibustion group (group B), selective acupuncture + electroacupuncture (group C), selective acupuncture + line-up needling on muscle region of meridian group (group D) and non-selective filiform needle group (group E). Four sessions of treatment were required in each group. Separately, during the enrollment, after 4 sessions of treatment, in 1 month and 3 months of follow-up after treatment, House-Brackmann Scale, Facial Disability Index Scale and Degree of Facial Nerve Paralysis (NFNP) were adopted for efficacy assessment. And the efficacy systematic analysis was provided in view of the intervention time and nerve localization of disease separately. The curative rates of intervention in acute stage and resting stage were 50.1% (223/445) and 52.1% (162/311), which were superior to recovery stage (25.9%, 35/135) separately. There were no statistical significant differences in efficacy in comparison among 5 treatment programs at the same stage (all P > 0.05). The efficacy of intervention of group A and group E in acute stage was superior to that in recovery stage (both P < 0.01). The difference was significant statistically between the efficacy on the localization above chorda tympani nerve and that on the localization below the nerve in group D (P < 0.01). The efficacy on the localization below chorda tympani nerve was superior to the localization above the nerve. The best intervention time for the treatment of Bell's palsy is in acute stage and resting stage, meaning 1 to 3 weeks after occurrence. All of the 5 treatment programs are advantageous

  8. Tobacco smoking surveillance: is quota sampling an efficient tool for monitoring national trends? A comparison with a random cross-sectional survey.

    Directory of Open Access Journals (Sweden)

    Romain Guignard

    Full Text Available OBJECTIVES: It is crucial for policy makers to monitor the evolution of tobacco smoking prevalence. In France, this monitoring is based on a series of cross-sectional general population surveys, the Health Barometers, conducted every five years and based on random samples. A methodological study has been carried out to assess the reliability of a monitoring system based on regular quota sampling surveys for smoking prevalence. DESIGN / OUTCOME MEASURES: In 2010, current and daily tobacco smoking prevalences obtained in a quota survey on 8,018 people were compared with those of the 2010 Health Barometer carried out on 27,653 people. Prevalences were assessed separately according to the telephone equipment of the interviewee (landline phone owner vs "mobile-only", and logistic regressions were conducted in the pooled database to assess the impact of the telephone equipment and of the survey mode on the prevalences found. Finally, logistic regressions adjusted for sociodemographic characteristics were conducted in the random sample in order to determine the impact of the needed number of calls to interwiew "hard-to-reach" people on the prevalence found. RESULTS: Current and daily prevalences were higher in the random sample (respectively 33.9% and 27.5% in 15-75 years-old than in the quota sample (respectively 30.2% and 25.3%. In both surveys, current and daily prevalences were lower among landline phone owners (respectively 31.8% and 25.5% in the random sample and 28.9% and 24.0% in the quota survey. The required number of calls was slightly related to the smoking status after adjustment for sociodemographic characteristics. CONCLUSION: Random sampling appears to be more effective than quota sampling, mainly by making it possible to interview hard-to-reach populations.

  9. Differentiating intraprofessional attitudes toward paradigms in health care delivery among chiropractic factions: results from a randomly sampled survey

    Science.gov (United States)

    2014-01-01

    Background As health care has increased in complexity and health care teams have been offered as a solution, so too is there an increased need for stronger interprofessional collaboration. However the intraprofessional factions that exist within every profession challenge interprofessional communication through contrary paradigms. As a contender in the conservative spinal health care market, factions within chiropractic that result in unorthodox practice behaviours may compromise interprofessional relations and that profession’s progress toward institutionalization. The purpose of this investigation was to quantify the professional stratification among Canadian chiropractic practitioners and evaluate the practice perceptions of those factions. Methods A stratified random sample of 740 Canadian chiropractors was surveyed to determine faction membership and how professional stratification could be related to views that could be considered unorthodox to current evidence-based care and guidelines. Stratification in practice behaviours is a stated concern of mainstream medicine when considering interprofessional referrals. Results Of 740 deliverable questionnaires, 503 were returned for a response rate of 68%. Less than 20% of chiropractors (18.8%) were aligned with a predefined unorthodox perspective of the conditions they treat. Prediction models suggest that unorthodox perceptions of health practice related to treatment choices, x-ray use and vaccinations were strongly associated with unorthodox group membership (X2 =13.4, p = 0.0002). Conclusion Chiropractors holding unorthodox views may be identified based on response to specific beliefs that appear to align with unorthodox health practices. Despite continued concerns by mainstream medicine, only a minority of the profession has retained a perspective in contrast to current scientific paradigms. Understanding the profession’s factions is important to the anticipation of care delivery when considering

  10. Diurnal Variation and Spatial Distribution Effects on Sulfur Speciation in Aerosol Samples as Assessed by X-Ray Absorption Near-Edge Structure (XANES

    Directory of Open Access Journals (Sweden)

    Siwatt Pongpiachan

    2012-01-01

    Full Text Available This paper focuses on providing new results relating to the impacts of Diurnal variation, Vertical distribution, and Emission source on sulfur K-edge XANES spectrum of aerosol samples. All aerosol samples used in the diurnal variation experiment were preserved using anoxic preservation stainless cylinders (APSCs and pressure-controlled glove boxes (PCGBs, which were specially designed to prevent oxidation of the sulfur states in PM10. Further investigation of sulfur K-edge XANES spectra revealed that PM10 samples were dominated by S(VI, even when preserved in anoxic conditions. The “Emission source effect” on the sulfur oxidation state of PM10 was examined by comparing sulfur K-edge XANES spectra collected from various emission sources in southern Thailand, while “Vertical distribution effects” on the sulfur oxidation state of PM10 were made with samples collected from three different altitudes from rooftops of the highest buildings in three major cities in Thailand. The analytical results have demonstrated that neither “Emission source” nor “Vertical distribution” appreciably contribute to the characteristic fingerprint of sulfur K-edge XANES spectrum in PM10.

  11. A statistical model and national data set for partioning fish-tissue mercury concentration variation between spatiotemporal and sample characteristic effects

    Science.gov (United States)

    Wente, Stephen P.

    2004-01-01

    Many Federal, Tribal, State, and local agencies monitor mercury in fish-tissue samples to identify sites with elevated fish-tissue mercury (fish-mercury) concentrations, track changes in fish-mercury concentrations over time, and produce fish-consumption advisories. Interpretation of such monitoring data commonly is impeded by difficulties in separating the effects of sample characteristics (species, tissues sampled, and sizes of fish) from the effects of spatial and temporal trends on fish-mercury concentrations. Without such a separation, variation in fish-mercury concentrations due to differences in the characteristics of samples collected over time or across space can be misattributed to temporal or spatial trends; and/or actual trends in fish-mercury concentration can be misattributed to differences in sample characteristics. This report describes a statistical model and national data set (31,813 samples) for calibrating the aforementioned statistical model that can separate spatiotemporal and sample characteristic effects in fish-mercury concentration data. This model could be useful for evaluating spatial and temporal trends in fishmercury concentrations and developing fish-consumption advisories. The observed fish-mercury concentration data and model predictions can be accessed, displayed geospatially, and downloaded via the World Wide Web (http://emmma.usgs.gov). This report and the associated web site may assist in the interpretation of large amounts of data from widespread fishmercury monitoring efforts.

  12. Quantifying variation in δ13C and δ15N isotopes within and between feathers and individuals: Is one sample enough?

    Science.gov (United States)

    Grecian, W James; McGill, Rona A R; Phillips, Richard A; Ryan, Peter G; Furness, Robert W

    Studies of avian migration increasingly use stable isotope analysis to provide vital trophic and spatial markers. However, when interpreting differences in stable isotope values of feathers, many studies are forced to make assumptions about the timing of moult. A fundamental question remains about the consistency of these values within and between feathers from the same individual. In this study, we examine variation in carbon and nitrogen isotopes by sub-sampling feathers collected from the wings of adults of two small congeneric petrel species, the broad-billed Pachyptila vittata and Antarctic prion P. desolata. Broad-billed prion feather vane material was enriched in 15N compared to feather rachis material, but there was no detectable difference in δ13C. Comparison of multiple samples taken from Antarctic prion feathers indicated subtle difference in isotopes; rachis material was enriched in 13C compared to vane material, and there were differences along the length of the feather, with samples from the middle and tip of the feather depleted in 15N compared to those from the base. While the greatest proportion of model variance was explained by differences between feathers and individuals, the magnitude of these within-feather differences was up to 0.5 ‰ in δ15N and 0.8 ‰ in δ13C. We discuss the potential drivers of these differences, linking isotopic variation to individual-level dietary differences, movement patterns and temporal dietary shifts. A novel result is that within-feather differences in δ13C may be attributed to differences in keratin structure within feathers, suggesting further work is required to understand the role of different amino acids. Our results highlight the importance of multiple sampling regimes that consider both within- and between-feather variation in studies using stable isotopes.

  13. Seasonal variation in natural abundance of 2H and 18O in urine samples from rural Nigeria.

    Science.gov (United States)

    Harbison, Justin E; Dugas, Lara R; Brieger, William; Tayo, Bamidele O; Alabi, Tunrayo; Schoeller, Dale A; Luke, Amy

    2015-07-01

    The doubly labeled water (DLW) method is used to measure free-living energy expenditure in humans. Inherent to this technique is the assumption that natural abundances of stable isotopes (2)H and (18)O in body water remain constant over the course of the measurement period and after elimination of the loading dose of DLW will return to the same predose level. To determine variability in the natural abundances of (2)H and (18)O in humans living in a region with seasonal shifts in rain patterns and sources of drinking water, over the course of 12 mo we collected weekly urine samples from four individuals living in southwest Nigeria as well as samples of their drinking water. From ongoing regional studies of hypertension, obesity, and energy expenditure, we estimated average water turnover rate, urine volumes, and sodium and potassium excretion. Results suggest that (2)H and (18)O in urine, mean concentrations of urinary sodium and potassium, urine volume, and total body turnover differed significantly from dry to rainy season. Additionally, seasonal weather variables (mean monthly maximum temperatures, total monthly rainfall, and minimum relative humidity) were all significantly associated with natural abundances in urine. No seasonal difference was observed in drinking water samples. Findings suggest that natural abundances in urine may not remain constant as assumed, and studies incorporating DLW measurements across the transition of seasons should interpret results with caution unless appropriate doses of the tracers are used. Copyright © 2015 the American Physiological Society.

  14. Variation in spatial and temporal incidence of the crustacean pathogen Hematodinium perezi in environmental samples from Atlantic Coastal Bays.

    Science.gov (United States)

    Hanif, Ammar W; Dyson, Whitney D; Bowers, Holly A; Pitula, Joseph S; Messick, Gretchen A; Jagus, Rosemary; Schott, Eric J

    2013-05-04

    Hematodinium perezi, a parasitic dinoflagellate, infects and kills blue crabs, Callinectes sapidus, along the Atlantic and Gulf coasts of the United States. The parasite proliferates within host hemolymph and tissues, and also produces free-swimming biflagellated dinospores that emerge from infected crabs. Infections in C. sapidus recur annually, and it is not known if biotic or environmental reservoirs contribute to reinfection and outbreaks. To address this data gap, a quantitative PCR assay based on the internal transcribed spacer 2 (ITS2) region of H. perezi rRNA genes was developed to asses the temporal and spatial incidence of the parasite in Delaware and Maryland coastal bays. A previously-used PCR assay for H. perezi, based on the small subunit rRNA gene sequence, was found to lack adequate species specificity to discriminate non-Hematodinium sp. dinoflagellate species in environmental samples. A new ITS2-targeted assay was developed and validated to detect H. perezi DNA in sediment and water samples using E. coli carrying the H. perezi rDNA genes. Application of the method to environmental samples identified potential hotspots in sediment in Indian River Inlet, DE and Chincoteague Bay, MD and VA. H. perezi DNA was not detected in co-occurring shrimp or snails, even during an outbreak of the parasite in C. sapidus. H. perezi is present in water and sediment samples in Maryland and Delaware coastal bays from April through November with a wide spatial and temporal variability in incidence. Sampling sites with high levels of H. perezi DNA in both bays share characteristics of silty, organic sediments and low tidal currents. The environmental detection of H. perezi in spring, ahead of peak prevalence in crabs, points to gaps in our understanding of the parasite's life history prior to infection in crabs as well as the mode of environmental transmission. To better understand the H. perezi life cycle will require further monitoring of the parasite in habitats as

  15. A non-random variation of monthly average temperatures and precipitation quantities in Romania during the period 2009-2012

    Directory of Open Access Journals (Sweden)

    Vlad D. MIRCOV

    2014-06-01

    Full Text Available Within this study we reflect non-randomness in the series of data concerning monthly average temperature and precipitation values registered in Romania during the period 2009-2012. We identified the slow increase in the monthly average temperature with 0.040C/months and a low decrease of average precipitation quantity with 0.29 mm/month. We also revealed that monthly average temperature and precipitation quantities series of data exposed behaviour close to Brown noise. The complex nature of the climate system and the unpredictability of weather are also reflected.

  16. Distribution of peak expiratory flow variability by age, gender and smoking habits in a random population sample aged 20-70 yrs

    NARCIS (Netherlands)

    Boezen, H M; Schouten, J. P.; Postma, D S; Rijcken, B

    1994-01-01

    Peak expiratory flow (PEF) variability can be considered as an index of bronchial lability. Population studies on PEF variability are few. The purpose of the current paper is to describe the distribution of PEF variability in a random population sample of adults with a wide age range (20-70 yrs),

  17. From Planning to Implementation: An Examination of Changes in the Research Design, Sample Size, and Precision of Group Randomized Trials Launched by the Institute of Education Sciences

    Science.gov (United States)

    Spybrook, Jessaca; Puente, Anne Cullen; Lininger, Monica

    2013-01-01

    This article examines changes in the research design, sample size, and precision between the planning phase and implementation phase of group randomized trials (GRTs) funded by the Institute of Education Sciences. Thirty-eight GRTs funded between 2002 and 2006 were examined. Three studies revealed changes in the experimental design. Ten studies…

  18. Evaluating effectiveness of down-sampling for stratified designs and unbalanced prevalence in Random Forest models of tree species distributions in Nevada

    Science.gov (United States)

    Elizabeth A. Freeman; Gretchen G. Moisen; Tracy S. Frescino

    2012-01-01

    Random Forests is frequently used to model species distributions over large geographic areas. Complications arise when data used to train the models have been collected in stratified designs that involve different sampling intensity per stratum. The modeling process is further complicated if some of the target species are relatively rare on the landscape leading to an...

  19. Genesis Solar Wind Sample 61422: Experiment in Variation of Sequence of Cleaning Solvent for Removing Carbon-Bearing Contamination

    Science.gov (United States)

    Allton, J. H.; Kuhlman, K. R.; Allums, K. K.; Gonzalez, C. P.; Jurewicz, A. J. G.; Burnett, D. S.; Woolum, D. S.

    2015-01-01

    The recovered Genesis collector fragments are heavily contaminated with crash-derived particulate debris. However, megasonic treatment with ultra-pure-water (UPW; resistivity (is) greater than18 meg-ohm-cm) removes essentially all particulate contamination greater than 5 microns in size [e.g.1] and is thus of considerable importance. Optical imaging of Si sample 60336 revealed the presence of a large C-rich particle after UPW treatment that was not present prior to UPW. Such handling contamination is occasionally observed, but such contaminants are normally easily removed by UPW cleaning. The 60336 particle was exceptional in that, surprisingly, it was not removed by additional UPW or by hot xylene or by aqua regia treatment. It was eventually removed by treatment with NH3-H2O2. Our best interpretation of the origin of the 60336 particle was that it was adhesive from the Post-It notes used to stabilize samples for transport from Utah after the hard landing. It is possible that the insoluble nature of the 60336 particle comes from interaction of the Post-It adhesive with UPW. An occasional bit of Post-It adhesive is not a major concern, but C particulate contamination also occurs from the heat shield of the Sample Return Capsule (SRC) and this is mixed with inorganic contamination from the SRC and the Utah landing site. If UPW exposure also produced an insoluble residue from SRC C, this would be a major problem in chemical treatments to produce clean surfaces for analysis. This paper reports experiments to test whether particulate contamination was removed more easily if UPW treatment was not used.

  20. Changes in prevalence of, and risk factors for, lameness in random samples of English sheep flocks: 2004-2013.

    Science.gov (United States)

    Winter, Joanne R; Kaler, Jasmeet; Ferguson, Eamonn; KilBride, Amy L; Green, Laura E

    2015-11-01

    The aims of this study were to update the prevalence of lameness in sheep in England and identify novel risk factors. A total of 1260 sheep farmers responded to a postal survey. The survey captured detailed information on the period prevalence of lameness from May 2012-April 2013 and the prevalence and farmer naming of lesions attributable to interdigital dermatitis (ID), severe footrot (SFR), contagious ovine digital dermatitis (CODD) and shelly hoof (SH), management and treatment of lameness, and farm and flock details. The global mean period prevalence of lameness fell between 2004 and 2013 from 10.6% to 4.9% and the geometric mean period prevalence of lameness fell from 5.4% (95% CL: 4.7%-6.0%) to 3.5% (95% CI: 3.3%-3.7%). In 2013, more farmers were using vaccination and antibiotic treatment for ID and SFR and fewer farmers were using foot trimming as a routine or therapeutic treatment than in 2004. Two over-dispersed Poisson regression models were developed with the outcome the period prevalence of lameness, one investigated associations with farmer estimates of prevalence of the four foot lesions and one investigated associations with management practices to control and treat lameness and footrot. A prevalence of ID>10%, SFR>2.5% and CODD>2.5% were associated with a higher prevalence of lameness compared with those lesions being absent, however, the prevalence of SH was not associated with a change in risk of lameness. A key novel management risk associated with higher prevalence of lameness was the rate of feet bleeding/100 ewes trimmed/year. In addition, vaccination of ewes once per year and selecting breeding replacements from never-lame ewes were associated with a decreased risk of lameness. Other factors associated with a lower risk of lameness for the first time in a random sample of farmers and a full risk model were: recognising lameness in sheep at locomotion score 1 compared with higher scores, treatment of the first lame sheep in a group compared

  1. Nutritional status and falls in community-dwelling older people: a longitudinal study of a population-based random sample.

    Science.gov (United States)

    Chien, Ming-Hung; Guo, How-Ran

    2014-01-01

    Falls are common in older people and may lead to functional decline, disability, and death. Many risk factors have been identified, but studies evaluating effects of nutritional status are limited. To determine whether nutritional status is a predictor of falls in older people living in the community, we analyzed data collected through the Survey of Health and Living Status of the Elderly in Taiwan (SHLSET). SHLSET include a series of interview surveys conducted by the government on a random sample of people living in community dwellings in the nation. We included participants who received nutritional status assessment using the Mini Nutritional Assessment Taiwan Version 2 (MNA-T2) in the 1999 survey when they were 53 years or older and followed up on the cumulative incidence of falls in the one-year period before the interview in the 2003 survey. At the beginning of follow-up, the 4440 participants had a mean age of 69.5 (standard deviation= 9.1) years, and 467 participants were "not well-nourished," which was defined as having an MNA-T2 score of 23 or less. In the one-year study period, 659 participants reported having at least one fall. After adjusting for other risk factors, we found the associated odds ratio for falls was 1.73 (95% confidence interval, 1.23, 2.42) for "not well-nourished," 1.57 (1.30, 1.90) for female gender, 1.03 (1.02, 1.04) for one-year older, 1.55 (1.22, 1.98) for history of falls, 1.34 (1.05, 1.72) for hospital stay during the past 12 months, 1.66 (1.07, 2.58) for difficulties in activities of daily living, and 1.53 (1.23, 1.91) for difficulties in instrumental activities of daily living. Nutritional status is an independent predictor of falls in older people living in the community. Further studies are warranted to identify nutritional interventions that can help prevent falls in the elderly.

  2. Effects of the variation of samples geometry on radionuclide calibrator response for radiopharmaceuticals used in nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Antonio Morais de Sa; Fragoso, Maria Conceicao de Farias; Oliveira, Mercia L. [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil)

    2011-07-01

    In the nuclear medicine practice, the accurate knowledge of the activity of radiopharmaceuticals which will be administered to the subjects is an important factor to ensure the success of diagnosis or therapy. The instrument used for this purpose is the radionuclide calibrator. The radiopharmaceuticals are usually contained on glass vials or syringes. However, the radionuclide calibrators response is sensitive to the measurement geometry. In addition, the calibration factors supplied by manufactures are valid only for single sample geometry. To minimize the uncertainty associated with the activity measurements, it is important to use the appropriate corrections factors for the each radionuclide in the specific geometry in which the measurement is to be made. The aims of this work were to evaluate the behavior of radionuclide calibrators varying the geometry of radioactive sources and to determine experimentally the correction factors for different volumes and containers types commonly used in nuclear medicine practice. The measurements were made in two ionization chambers of different manufacturers (Capintec and Biodex), using four radionuclides with different photon energies: {sup 18}F, {sup 99m}Tc, {sup 131}I and {sup 201}Tl. The results confirm the significant dependence of radionuclide calibrators reading on the sample geometry, showing the need of use correction factors in order to minimize the errors which affect the activity measurements. (author)

  3. On the sum of squared η-μ random variates with application to the performance of wireless communication systems

    KAUST Repository

    Ansari, Imran Shafique

    2013-06-01

    The probability density function (PDF) and cumulative distribution function of the sum of L independent but not necessarily identically distributed squared η-μ variates, applicable to the output statistics of maximal ratio combining (MRC) receiver operating over η-μ fading channels that includes the Hoyt and the Nakagami-m models as special cases, is presented in closed-form in terms of the Fox\\'s H function. Further analysis, particularly on the bit error rate via PDF-based approach, is also represented in closed form in terms of the extended Fox\\'s H function (H). The proposed new analytical results complement previous results and are illustrated by extensive numerical and Monte Carlo simulation results. © 2013 IEEE.

  4. The vls antigenic variation systems of Lyme disease Borrelia: eluding host immunity through both random, segmental gene conversion and framework heterogeneity

    Science.gov (United States)

    Norris, Steven J.

    2015-01-01

    Summary Spirochetes that cause Lyme borreliosis (also called Lyme disease) possess the vls locus, encoding an elaborate antigenic variation system. This locus contains the expression site vlsE as well as a contiguous array of vls silent cassettes, which contain variations of the central cassette region of vlsE. The locus is present on one of the many linear plasmids in the organism, e.g. plasmid lp28-1 in the strain B. burgdorferi B31. Changes in the sequence of vlsE occur continuously during mammalian infection and consist of random, segmental, unidirectional recombination events between the silent cassettes and the cassette region of vlsE. These gene conversion events do not occur during in vitro culture or the tick portion of the infection cycle of Borrelia burgdorferi or the other related Borrelia species that cause Lyme disease. The mechanism of recombination is largely unknown, but requires the RuvAB Holliday junction branch migrase. Other features of the vls locus also appear to be required, including cis locations of vlsE and the silent cassettes and high G+C content and GC skew. The vls system is required for long-term survival of Lyme Borrelia in infected mammals and represents an important mechanism of immune evasion. In addition to sequence variation, immune selection also results in significant heterogeneity in the sequence of the surface lipoprotein VlsE. Despite antigenic variation, VlsE generates a robust antibody response, and both full length VlsE and the C6 peptide (corresponding to invariant region 6) are widely used in immunodiagnostic tests for Lyme disease. PMID:26104445

  5. Long-term sampling of CO2 from waste-to-energy plants: 14C determination methodology, data variation and uncertainty

    DEFF Research Database (Denmark)

    Fuglsang, Karsten; Pedersen, Niels Hald; Larsen, Anna Warberg

    2014-01-01

    emissions were observed (between 56% and 71% biogenic CO2). These variations confirmed that biomass fractions in the waste can vary considerably, not only from day to day but also from month to month. An uncertainty budget for the measurement method itself showed that the expanded uncertainty of the method...... was ± 4.0 pmC (95 % confidence interval) at 62 pmC. The long-term sampling method was found to be useful for waste incinerators for determination of annual fossil and biogenic CO2 emissions with relatively low uncertainty....

  6. Association between genetic variation in a region on chromosome 11 and schizophrenia in large samples from Europe

    DEFF Research Database (Denmark)

    Rietschel, M; Mattheisen, M; Degenhardt, F

    2012-01-01

    Recent molecular studies have implicated common alleles of small to moderate effect and rare alleles with larger effect sizes in the genetic architecture of schizophrenia (SCZ). It is expected that the reliable detection of risk variants with very small effect sizes can only be achieved through.......25). This finding was replicated in 23 206 independent samples of European ancestry (P=0.0029, OR=1.11). In a subsequent imaging genetics study, healthy carriers of the risk allele exhibited altered activation in the cingulate cortex during a cognitive control task. The area of interest is a critical interface...... between emotion regulation and cognition that is structurally and functionally abnormal in SCZ and bipolar disorder.Molecular Psychiatry advance online publication, 12 July 2011; doi:10.1038/mp.2011.80....

  7. Sleep quality and body composition variations in obese male adults after 14 weeks of yoga intervention: A randomized controlled trial

    Directory of Open Access Journals (Sweden)

    P B Rshikesan

    2017-01-01

    Full Text Available Background: Obesity is a big challenge all over the world. It is associated with many noncommunicable diseases. Yoga known to be add-on treatment may be effective for obesity control. Aim: To assess the effect of integrated approach of yoga therapy (IAYT for body composition and quality of sleep in adult obese male. Subjects and Methods: A randomized controlled trial was conducted for 14 weeks on obese male of urban setting. Eighty individuals were randomly divided into two groups, i.e., yoga group (n = 40; age; 40.03 ± 8.74 years, body mass index [BMI] 28.7 ± 2.35 kg/m2 and control group (age; 42.20 ± 12.06 years, BMI 27.70 ± 2.05 kg/m2. The IAYT was imparted to yoga group for 1½ hour for 5 days in a week for 14 weeks. The control group continued their regular activities. The body composition by InBody R20 and sleep quality by Pittsburgh Sleep Quality Index (PSQI were assessed. Statistical analysis was done for within and between groups using SPSS version 21. The correlation analysis was done on the difference in pre-post values. Results: The results showed that weight (P = 0.004, BMI (P = 0.008, bone mass (P = 0.017, obesity degree (P = 0.005, and mineral mass (P = 0.046 were improved in yoga group and no change in control group (P > 0.05. The global score of PSQI improved (P = 0.017 in yoga group alone. Conclusion: The results indicate the beneficial effects of IAYT on body composition and sleep quality in obese males. The yoga practice may reduce obesity with the improvement in quality of life.

  8. Pressure support improves oxygenation and lung protection compared to pressure-controlled ventilation and is further improved by random variation of pressure support.

    Science.gov (United States)

    Spieth, Peter M; Carvalho, Alysson R; Güldner, Andreas; Kasper, Michael; Schubert, René; Carvalho, Nadja C; Beda, Alessandro; Dassow, Constanze; Uhlig, Stefan; Koch, Thea; Pelosi, Paolo; Gama de Abreu, Marcelo

    2011-04-01

    To explore whether 1) conventional pressure support ventilation improves lung function and attenuates the pulmonary inflammatory response compared to pressure-controlled ventilation and 2) random variation of pressure support levels (noisy pressure support ventilation) adds further beneficial effects to pressure support ventilation. Three-arm, randomized, experimental study. University hospital research facility. Twenty-four juvenile pigs. Acute lung injury was induced by surfactant depletion. Animals were randomly assigned to 6 hrs of mechanical ventilation (n = 8 per group) with either 1) pressure-controlled ventilation, 2) pressure support ventilation, or 3) noisy pressure support ventilation. During noisy pressure support ventilation, the pressure support varied randomly, with values following a normal distribution. In all groups, the driving pressures were set to achieve a mean tidal volume of 6 mL/kg. At the end of experiments, animals were killed and lungs extracted for histologic and biochemical analysis. Respiratory, gas-exchange, and hemodynamics variables were assessed hourly. The diffuse alveolar damage and the inflammatory response of lungs were quantified. Pressure support ventilation and noisy pressure support ventilation improved gas exchange and were associated with reduced histologic damage and interleukin-6 concentrations in lung tissue compared to pressure-controlled ventilation. Noisy pressure support ventilation further improved gas exchange and decreased the inspiratory effort while reducing alveolar edema and inflammatory infiltration compared to pressure support ventilation. In this model of acute lung injury, pressure support ventilation and noisy pressure support ventilation attenuated pulmonary inflammatory response and improved gas exchange as compared to pressure-controlled ventilation. Noisy pressure support ventilation further improved gas exchange, reduced the inspiratory effort, and attenuated alveolar edema and inflammatory

  9. Sources of Variation on the Mini-Mental State Examination in a Population-Based Sample of Centenarians

    Science.gov (United States)

    Dai, Ting; Davey, Adam; Woodard, John L.; Miller, L. Stephen; Gondo, Yasuyuki; Kim, Seock-Ho; Poon, Leonard W.

    2013-01-01

    Centenarians represent a rare but rapidly growing segment of the oldest-old. This study presents item-level data from the Mini-Mental State Examination (MMSE, M=16.2, SD=8.8, Range 0–30) in a cross-sectional, population-based sample of 244 centenarians and near-centenarians (aged 98–108, 16% men, 21% African-American, 38% community-dwelling) from the Georgia Centenarian Study (2001–2008) by age, education, sex, race, and residential status. Multiple-Indicator Multiple-Causes (MIMIC) models were used to identify systematic domain-level differences on MMSE scores by key demographic characteristics in this age group. Indirect effects of age, educational attainment, race, and residential status were found on MMSE scores. Direct effects were limited to concentration for education and race, and orientation for residential status. Mean levels of cognitive functioning in centenarians were low, with mean values below most commonly-used cut-offs. Overall scores on the MMSE differed as a function of age, education, race, and residential status, with differences in scale performance limited primarily to concentration and orientation, with no evidence for interactions among centenarian characteristics. Adjusting for education was not sufficient to account for differences by race; adjusting for residential status was not sufficient to account for differences by age. PMID:23889552

  10. Genetic variation in the CYP1A1 gene is related to circulating PCB118 levels in a population-based sample

    Energy Technology Data Exchange (ETDEWEB)

    Lind, Lars [Department of Medical Sciences, Cardiovascular Epidemiology, Uppsala University, Uppsala (Sweden); Penell, Johanna [Department of Medical Sciences, Occupational and Environmental Medicine, Uppsala University, Uppsala (Sweden); Syvänen, Anne-Christine; Axelsson, Tomas [Department of Medical Sciences, Molecular Medicine and Science for Life Laboratory, Uppsala University, Uppsala (Sweden); Ingelsson, Erik [Department of Medical Sciences, Molecular Epidemiology and Science for Life Laboratory, Uppsala University, Uppsala (Sweden); Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford (United Kingdom); Morris, Andrew P.; Lindgren, Cecilia [Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford (United Kingdom); Salihovic, Samira; Bavel, Bert van [MTM Research Centre, School of Science and Technology, Örebro University, Örebro (Sweden); Lind, P. Monica, E-mail: monica.lind@medsci.uu.se [Department of Medical Sciences, Occupational and Environmental Medicine, Uppsala University, Uppsala (Sweden)

    2014-08-15

    Several of the polychlorinated biphenyls (PCBs), i.e. the dioxin-like PCBs, are known to induce the P450 enzymes CYP1A1, CYP1A2 and CYP1B1 by activating the aryl hydrocarbon receptor (Ah)-receptor. We evaluated if circulating levels of PCBs in a population sample were related to genetic variation in the genes encoding these CYPs. In the population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study (1016 subjects all aged 70), 21 SNPs in the CYP1A1, CYP1A2 and CYP1B1 genes were genotyped. Sixteen PCB congeners were analysed by high-resolution chromatography coupled to high-resolution mass spectrometry (HRGC/ HRMS). Of the investigated relationships between SNPs in the CYP1A1, CYP1A2 and CYP1B1 and six PCBs (congeners 118, 126, 156, 169, 170 and 206) that captures >80% of the variation of all PCBs measured, only the relationship between CYP1A1 rs2470893 was significantly related to PCB118 levels following strict adjustment for multiple testing (p=0.00011). However, there were several additional SNPs in the CYP1A2 and CYP1B1 that showed nominally significant associations with PCB118 levels (p-values in the 0.003–0.05 range). Further, several SNPs in the CYP1B1 gene were related to both PCB156 and PCB206 with p-values in the 0.005–0.05 range. Very few associations with p<0.05 were seen for PCB126, PCB169 or PCB170. Genetic variation in the CYP1A1 was related to circulating PCB118 levels in the general elderly population. Genetic variation in CYP1A2 and CYP1B1 might also be associated with other PCBs. - Highlights: • We studied the relationship between PCBs and the genetic variation in the CYP genes. • Cross sectional data from a cohort of elderly were analysed. • The PCB levels were evaluated versus 21 SNPs in three CYP genes. • PCB 118 was related to variation in the CYP1A1 gene.

  11. Genomic distribution and inter-sample variation of non-CpG methylation across human cell types.

    Science.gov (United States)

    Ziller, Michael J; Müller, Fabian; Liao, Jing; Zhang, Yingying; Gu, Hongcang; Bock, Christoph; Boyle, Patrick; Epstein, Charles B; Bernstein, Bradley E; Lengauer, Thomas; Gnirke, Andreas; Meissner, Alexander

    2011-12-01

    DNA methylation plays an important role in development and disease. The primary sites of DNA methylation in vertebrates are cytosines in the CpG dinucleotide context, which account for roughly three quarters of the total DNA methylation content in human and mouse cells. While the genomic distribution, inter-individual stability, and functional role of CpG methylation are reasonably well understood, little is known about DNA methylation targeting CpA, CpT, and CpC (non-CpG) dinucleotides. Here we report a comprehensive analysis of non-CpG methylation in 76 genome-scale DNA methylation maps across pluripotent and differentiated human cell types. We confirm non-CpG methylation to be predominantly present in pluripotent cell types and observe a decrease upon differentiation and near complete absence in various somatic cell types. Although no function has been assigned to it in pluripotency, our data highlight that non-CpG methylation patterns reappear upon iPS cell reprogramming. Intriguingly, the patterns are highly variable and show little conservation between different pluripotent cell lines. We find a strong correlation of non-CpG methylation and DNMT3 expression levels while showing statistical independence of non-CpG methylation from pluripotency associated gene expression. In line with these findings, we show that knockdown of DNMTA and DNMT3B in hESCs results in a global reduction of non-CpG methylation. Finally, non-CpG methylation appears to be spatially correlated with CpG methylation. In summary these results contribute further to our understanding of cytosine methylation patterns in human cells using a large representative sample set.

  12. Mood, motives, and gambling in young adults: an examination of within- and between-person variations using experience sampling.

    Science.gov (United States)

    Goldstein, Abby L; Stewart, Sherry H; Hoaken, Peter N S; Flett, Gordon L

    2014-03-01

    It is well established that young adults are a population at risk for problem gambling and that young adults gamble for various reasons, including positive mood enhancement and negative mood reduction. Although these motives have been identified as important proximal predictors of gambling, the research to date has focused on between-subjects relationships. What is missing is a process-level understanding of the specific within-subjects relations between mood-regulation motives for gambling, mood states, and gambling behaviors. The current study used experience sampling to assess the specific link between gambling motives, mood states, and gambling behavior. Participants were 108 young adults (ages 19-24 years), who completed baseline measures of gambling motives and gambling problems and then reported on their mood states and gambling behavior three times a day for 30 days. Multilevel modeling analyses revealed a significant positive moderating effect for enhancement motives on the relationship between positive mood and amount of time spent gambling and number of drinks consumed while gambling. In addition, problem gambling status was associated with consuming fewer drinks while gambling at higher levels of positive mood, and spending more money than intended at higher levels of negative mood. Unexpectedly, there was only one moderating effect for coping motives on the mood-gambling relationship; low coping motivated gamblers consumed more alcohol while gambling at higher levels of positive mood, whereas high coping motivated gamblers did not change their drinking in response to positive mood. The current findings highlight enhancement motives as risky motives for young adult gambling, particularly in the context of positive mood, and suggest that gambling interventions should include strategies to address positive mood management.

  13. Stages of change of the readiness to quit smoking among a random sample of minority Arab male smokers in Israel.

    Science.gov (United States)

    Daoud, Nihaya; Hayek, Samah; Sheikh Muhammad, Ahmad; Abu-Saad, Kathleen; Osman, Amira; Thrasher, James F; Kalter-Leibovici, Ofra

    2015-07-16

    Despite advanced smoking prevention and cessation policies in many countries, the prevalence of cigarette smoking among indigenous and some ethnic minorities continues to be high. This study examined the stages of change (SOC) of the readiness to quit smoking among Arab men in Israel shortly after new regulations of free-of-charge smoking cessation workshops and subsidized medications were introduced through primary health care clinics. We conducted a countrywide study in Israel between 2012-2013. Participants, 735 current smokers; 18-64 years old; were recruited from a stratified random sample and interviewed face-to-face using a structured questionnaire in Arabic. We used ordered regression to examine the contribution of socio-economic position (SEP), health status, psychosocial attributes, smoking-related factors, and physician advice to the SOC of the readiness to quit smoking (pre-contemplation, contemplation and preparation). Of the current smokers, 61.8% were at the pre-contemplation stage, 23.8% were at the contemplation stage, and only 14.4% were at the preparation stage. In the multinomial analysis, factors significantly (P stage compared to pre-contemplation stage included [odds ratio (OR), 95% confidence interval (CI)]: chronic morbidity [0.52, (0.31-0.88)], social support [1.35, (1.07-1.70)], duration of smoking for 11-21 years [1.94, (1.07-3.50)], three or more previous attempts to quit [2.27, (1.26-4.01)], knowledge about smoking hazards [1.75, (1.29-2.35)], positive attitudes toward smoking prevention [1.44, (1.14-1.82)], and physician advice to quit smoking [1.88, (1.19-2.97)]. The factors significantly (P stage compared to pre-contemplation stage were [OR, (95 % CI)]: chronic morbidity [0.36, (0.20-0.67)], anxiety [1.07, (1.01-1.13)], social support [1.34, (1.01-1.78)], duration of smoking 5 years or less [2.93, (1.14-7.52)], three or more previous attempts to quit [3.16, (1.60-6.26)], knowledge about smoking hazards [1.57, (1.10-2.21)], and

  14. The Tracking Study: description of a randomized controlled trial of variations on weight tracking frequency in a behavioral weight loss program.

    Science.gov (United States)

    Linde, Jennifer A; Jeffery, Robert W; Crow, Scott J; Brelje, Kerrin L; Pacanowski, Carly R; Gavin, Kara L; Smolenski, Derek J

    2015-01-01

    Observational evidence from behavioral weight control trials and community studies suggests that greater frequency of weighing oneself, or tracking weight, is associated with better weight outcomes. Conversely, it has also been suggested that frequent weight tracking may have a negative impact on mental health and outcomes during weight loss, but there are minimal experimental data that address this concern in the context of an active weight loss program. To achieve the long-term goal of strengthening behavioral weight loss programs, the purpose of this randomized controlled trial (the Tracking Study) is to test variations on frequency of self-weighing during a behavioral weight loss program, and to examine psychosocial and mental health correlates of weight tracking and weight loss outcomes. This paper describes the study design, intervention features, recruitment, and baseline characteristics of participants enrolled in the Tracking Study. Three hundred thirty-nine overweight and obese adults were recruited and randomized to one of three variations on weight tracking frequency during a 12-month weight loss program with a 12-month follow-up: daily weight tracking, weekly weight tracking, or no weight tracking. The primary outcome is weight in kilograms at 24 months. The weight loss program integrates each weight tracking instruction with standard behavioral weight loss techniques (goal setting, self-monitoring, stimulus control, dietary and physical activity enhancements, lifestyle modifications); participants in weight tracking conditions were provided with wireless Internet technology (wi-fi-enabled digital scales and touchscreen personal devices) to facilitate weight tracking during the study. This study was successful in recruiting adult male and female participants and is positioned to enhance the standard of care with regard to weight tracking recommendations. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Causes of variation in BCG vaccine efficacy: examining evidence from the BCG REVAC cluster randomized trial to explore the masking and the blocking hypotheses.

    Science.gov (United States)

    Barreto, Mauricio L; Pilger, Daniel; Pereira, Susan M; Genser, Bernd; Cruz, Alvaro A; Cunha, Sergio S; Sant'Anna, Clemax; Hijjar, Miguel A; Ichihara, Maria Y; Rodrigues, Laura C

    2014-06-24

    BCG protection varies and in some places (nearest the equator) is low or absent. Understanding this variation can inform the efforts to develop new vaccines against tuberculosis. Two main hypotheses are used to explain this variation: under masking, new vaccines are unlikely to increase protection; under blocking new vaccines have a greater potential to be effective when BCG is not. We conducted a cluster randomized trial to explored the masking and blocking hypotheses by studying BCG vaccine efficacy of neonatal vaccination and when administered for the first or a second (revaccination) time at school age in two sites (Manaus close and Salvador further south from the equator). Seven hundred and sixty three state schools were matched on socio economic characteristics of the neighborhood and 239,934 children were randomized to vaccine (BCG vaccination at school age) or control group. Protection by first BCG vaccination at school age was high in Salvador (34%, 95% CI 7-53%, p=0.017) but low in Manaus (8%, 95% CI t0 39-40%, p=0.686). For revaccination at school age, protection was modest in Salvador (19%, 95% CI 3-33%, p=0.022) and absent in Manaus (1%, 95% CI to 27-23%, p=0.932). Vaccine efficacy for neonatal vaccination was similar in Salvador (40%, 95% CI 22-54%, pBCG efficacy was marked when vaccine was given at school age but absent at birth, which points towards blocking as the dominant mechanism. New tuberculosis vaccines that overcome or by pass this blocking effect could confer protection in situations where BCG is not protective. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. The Accuracy of Pass/Fail Decisions in Random and Difficulty-Balanced Domain-Sampling Tests.

    Science.gov (United States)

    Schnipke, Deborah L.

    A common practice in some certification fields (e.g., information technology) is to draw items from an item pool randomly and apply a common passing score, regardless of the items administered. Because these tests are commonly used, it is important to determine how accurate the pass/fail decisions are for such tests and whether fairly small,…

  17. Multifunctional Polymeric Scaffolds for Enhancement of PARACEST Contrast Sensitivity and Performance: The Effects of Random Copolymer Variations

    Science.gov (United States)

    Wu, Yunkou; Zhao, Piyu; Kiefer, Garry E.; Sherry, A. Dean

    2010-01-01

    A DOTA (1,4,7,10-tetraazacyclododecane-N,N’,N“,N’”-tetraacetic acid) tetraamide ligand having a single acrylamide side-chain (M1) was copolymerized with either 2-methylacrylic acid (MAA), 2-(acryloylamino)-2-methyl-1-propanesulfonic acid (AMPS) or N-isopropylacrylamide (NIPAM) to create a series of linear random copolymers using classical free radical chain polymerization chemistry. The metal ion binding properties of hydrolyzed M1 were investigated by pH potentiometry and the europium (III) complexes of the resulting heteropolymers were evaluated as PARACEST imaging agents. All polymeric agents were found to possess similar intermediate-to-slow water exchange and CEST characteristics as the parent EuDOTA-tetraamide monomer. Consistent with basic multiplexing principles, the highest molecular weight polymer, Eu-DMAA 3.1, also showed the highest CEST sensitivity with a detection limit of 20 ± 2 μM. The second arylamide component gave polymers with widely different chemical characteristics and CEST properties. In particular, the Eu-DNIPAM 4.0 and Eu-DMAA 4.1 polymers displayed different solubility characteristics as a function of pH or temperature which, in turn, affected the water exchange and CEST properties of the corresponding agents. It was concluded that introduction of hydrophobic groups into the polymer backbone reduces solvent accessibility to the Eu3+ component, effectively slowing water exchange between the inner-sphere water coordination position at each Eu3+ center with bulk water. The CEST properties of the heteropolymers when dissolved in plasma suggest that the more hydrophobic characteristics of these polymers could be advantageous for in vivo applications. PMID:20838469

  18. An Alternative Ratio-Cum-Product Estimator of Finite Population Mean Using Coefficient of Kurtosis of Two Auxiliary Variates in Two-Phase Sampling

    Directory of Open Access Journals (Sweden)

    Balkishan Sharma

    2014-10-01

    Full Text Available Normal 0 MicrosoftInternetExplorer4 This paper deals with the problem of estimation of population mean in two-phase sampling. A ratio-product estimator of population mean using known coefficient of kurtosis of two auxiliary variates has been proposed. In fact, it is a two-phase sampling version of Tailor et al. (2010 estimator and its properties are studied. Proposed estimator has been compared with usual unbiased estimator, classical ratio and product estimator in two-phase sampling, and two-phase sampling versions of Singh (1967 and Singh et al. (2004 estimators respectively. To judge the merits of the proposed estimator over other estimators an empirical study is also carried out. /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";}

  19. An Iterative Algorithm for Efficient Estimation of the Mean of a Normal Population Using Computational-Statistical Intelligence & Sample Counterpart of Rather-Very-Large Though Unknown Coefficient of Variation with a Small- Sample

    Directory of Open Access Journals (Sweden)

    Ashok Sahai

    2016-02-01

    Full Text Available This paper addresses the issue of finding the most efficient estimator of the normal population mean when the population “Coefficient of Variation (C. V.” is ‘Rather-Very-Large’ though unknown, using a small sample (sample-size ≤ 30. The paper proposes an “Efficient Iterative Estimation Algorithm exploiting sample “C. V.” for an efficient Normal Mean estimation”. The MSEs of the estimators per this strategy have very intricate algebraic expression depending on the unknown values of population parameters, and hence are not amenable to an analytical study determining the extent of gain in their relative efficiencies with respect to the Usual Unbiased Estimator (sample mean ~ Say ‘UUE’. Nevertheless, we examine these relative efficiencies of our estimators with respect to the Usual Unbiased Estimator, by means of an illustrative simulation empirical study. MATLAB 7.7.0.471 (R2008b is used in programming this illustrative ‘Simulated Empirical Numerical Study’.DOI: 10.15181/csat.v4i1.1091

  20. Individual-level variation and higher-level interpretations of space use in wide-ranging species: An albatross case study of sampling effects

    Directory of Open Access Journals (Sweden)

    Sarah Elizabeth Gutowsky

    2015-11-01

    Full Text Available Marine ecologists and managers need to know the spatial extent of at-sea areas most frequented by the groups of wildlife they study or manage. Defining group-specific ranges and distributions (i.e. space use at the level of species, population, age-class, etc. can help to identify the source or severity of common or distinct threats among different at-risk groups. In biologging studies, this is accomplished by estimating the space use of a group based on a sample of tracked individuals. A major assumption of these studies is consistency in individual movements among members of a group. The implications of scaling up individual-level tracking data to infer higher-level spatial patterns for groups (i.e. size and extent of areas used, overlap or segregation among groups is not well documented for wide-ranging pelagic species with high potential for individual variation in space use. We present a case study exploring the effects of sampling (i.e. number and identity of individuals contributing to an analysis on defining group-specific space use with year-round multi-colony tracking data from two highly vagile species, Laysan (Phoebastria immutabilis and black-footed (P. nigripes albatrosses. The results clearly demonstrate that caution is warranted when defining space use for a specific species-colony-period group based on datasets of small, intermediate, or relatively large sample sizes (ranging from n=3-42 tracked individuals due to a high degree of individual-level variation in movements. Overall, we provide further support to the recommendation that biologging studies aiming to define higher-level patterns in space use exercise restraint in the scope of inference, particularly when pooled Kernel Density Estimation techniques are applied to small datasets for wide-ranging species. Transparent reporting in respect to the potential limitations of the data can in turn better inform both biological interpretations and science-based management

  1. On the Use of Biomineral Oxygen Isotope Data to Identify Human Migrants in the Archaeological Record: Intra-Sample Variation, Statistical Methods and Geographical Considerations.

    Directory of Open Access Journals (Sweden)

    Emma Lightfoot

    Full Text Available Oxygen isotope analysis of archaeological skeletal remains is an increasingly popular tool to study past human migrations. It is based on the assumption that human body chemistry preserves the δ18O of precipitation in such a way as to be a useful technique for identifying migrants and, potentially, their homelands. In this study, the first such global survey, we draw on published human tooth enamel and bone bioapatite data to explore the validity of using oxygen isotope analyses to identify migrants in the archaeological record. We use human δ18O results to show that there are large variations in human oxygen isotope values within a population sample. This may relate to physiological factors influencing the preservation of the primary isotope signal, or due to human activities (such as brewing, boiling, stewing, differential access to water sources and so on causing variation in ingested water and food isotope values. We compare the number of outliers identified using various statistical methods. We determine that the most appropriate method for identifying migrants is dependent on the data but is likely to be the IQR or median absolute deviation from the median under most archaeological circumstances. Finally, through a spatial assessment of the dataset, we show that the degree of overlap in human isotope values from different locations across Europe is such that identifying individuals' homelands on the basis of oxygen isotope analysis alone is not possible for the regions analysed to date. Oxygen isotope analysis is a valid method for identifying first-generation migrants from an archaeological site when used appropriately, however it is difficult to identify migrants using statistical methods for a sample size of less than c. 25 individuals. In the absence of local previous analyses, each sample should be treated as an individual dataset and statistical techniques can be used to identify migrants, but in most cases pinpointing a specific

  2. Comparing cluster-level dynamic treatment regimens using sequential, multiple assignment, randomized trials: Regression estimation and sample size considerations

    OpenAIRE

    NeCamp, Timothy; Kilbourne, Amy; Almirall, Daniel

    2016-01-01

    Cluster-level dynamic treatment regimens can be used to guide sequential, intervention or treatment decision-making at the cluster level in order to improve outcomes at the individual or patient-level. In a cluster-level DTR, the intervention or treatment is potentially adapted and re-adapted over time based on changes in the cluster that could be impacted by prior intervention, including based on aggregate measures of the individuals or patients that comprise it. Cluster-randomized sequentia...

  3. Approximating the variance of estimated means for systematic random sampling, illustrated with data of the French Soil Monitoring Network

    NARCIS (Netherlands)

    Brus, D.J.; Saby, N.P.A.

    2016-01-01

    In France like in many other countries, the soil is monitored at the locations of a regular, square grid thus forming a systematic sample (SY). This sampling design leads to good spatial coverage, enhancing the precision of design-based estimates of spatial means and totals. Design-based

  4. Variation in levels of serum inhibin B, testosterone, estradiol, luteinizing hormone, follicle-stimulating hormone, and sex hormone-binding globulin in monthly samples from healthy men during a 17-month period

    DEFF Research Database (Denmark)

    Andersson, Anna-Maria; Carlsen, Elisabeth; Petersen, Jørgen Holm

    2003-01-01

    To obtain information on the scale of the intraindividual variation in testicular hormone, blood samples for inhibin B determination were collected monthly in 27 healthy male volunteers during a 17-month period. In addition, the traditional reproductive hormones FSH, LH, testosterone, estradiol....... A seasonal variation was observed in LH and testosterone levels, but not in the levels of the other hormones. The seasonal variation in testosterone levels could be explained by the variation in LH levels. The seasonal variation in LH levels seemed to be related to the mean air temperature during the month...... before blood sampling, but not to the length of daylight or the hours of sunshine. In conclusion, our data showed that day to day levels of inhibin B are relatively constant in men and do not seem to be influenced by seasonal factors. In contrast, we found a seasonal variation in LH and testosterone...

  5. Endothelial nitric oxide synthase (G894T) gene polymorphism in a random sample of the Egyptian population: comparison with myocardial infarction patients.

    Science.gov (United States)

    Gad, Mohamed Z; Abdel Rahman, Mohamed F; Hashad, Ingy M; Abdel-Maksoud, Sahar M; Farag, Nabil M; Abou-Aisha, Khaled

    2012-07-01

    The aim of this study was to detect endothelial nitric oxide synthase (eNOS) Glu298Asp gene variants in a random sample of the Egyptian population, compare it with those from other populations, and attempt to correlate these variants with serum levels of nitric oxide (NO). The association of eNOS genotypes or serum NO levels with the incidence of acute myocardial infarction (AMI) was also examined. One hundred one unrelated healthy subjects and 104 unrelated AMI patients were recruited randomly from the 57357 Hospital and intensive care units of El Demerdash Hospital and National Heart Institute, Cairo, Egypt. eNOS genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Serum NO was determined spectrophotometrically. The genotype distribution of eNOS Glu298Asp polymorphism determined for our sample was 58.42% GG (wild type), 33.66% GT, and 7.92% TT genotypes while allele frequencies were 75.25% and 24.75% for G and T alleles, respectively. No significant association between serum NO and specific eNOS genotype could be detected. No significant correlation between eNOS genotype distribution or allele frequencies and the incidence of AMI was observed. The present study demonstrated the predominance of the homozygous genotype GG over the heterozygous GT and homozygous TT in random samples of Egyptian population. It also showed the lack of association between eNOS genotypes and mean serum levels of NO, as well as the incidence of AMI.

  6. Comparison of direct and indirect estimates of apparent total tract digestibility in swine with effort to reduce variation by pooling of multiple day fecal samples.

    Science.gov (United States)

    Jang, Y D; Lindemann, M D; Agudelo-Trujillo, J H; Escobar, C S; Kerr, B J; Inocencio, N; Cromwell, G L

    2014-10-01

    The intent of this study was to establish a fecal sampling procedure for the indicator method (IM) to provide digestibility values similar to those obtained by the total collection (TC) method. A total of 24 pigs (52.6 ± 1.5 kg) were fed 1 of 4 diets with a 2 × 2 factorial arrangement of virginiamycin and phytase (PHY) added to a corn-soybean meal diet with no inorganic P supplement. Pigs were housed in metabolism crates for a 5-d TC period after 7 d of adaptation. Immediately after the TC, a fecal collection period followed, using the IM by including 0.25% of Cr2O3 in the feed for 10 d. Fecal collection for the IM started the day after diets containing Cr2O3 were first fed, and continued for 9 consecutive days with a single grab sample per day. Similar portions of feces from d 5 to 9 were also composited into 4 samples to evaluate multi-day pooling combinations. Highly variable means and CV among samples for apparent total tract digestibility (ATTD) were observed at d 1 and 2 using the IM. The mean ATTD for DM, GE, and nutrients appeared to be stabilized by d 5 or 6 in all dietary treatments. The TC data seemed to have lower CV than the IM data for many components. Based on the linear broken-line analysis, fecal Cr concentration plateaued at d 3.75 (P Mean ATTD values by the IM were lower than those by the TC method for DM (P pooling of feces for the IM appears to be needed to provide greater accuracy and lower variations than a single grab sample.

  7. A drink is a drink? Variation in the amount of alcohol contained in beer, wine and spirits drinks in a US methodological sample.

    Science.gov (United States)

    Kerr, William C; Greenfield, Thomas K; Tujague, Jennifer; Brown, Stephan E

    2005-11-01

    Empirically based estimates of the mean alcohol content of beer, wine and spirits drinks from a national sample of US drinkers are not currently available. A sample of 310 drinkers from the 2000 National Alcohol Survey were re-contacted to participate in a telephone survey with specific questions about the drinks they consume. Subjects were instructed to prepare their usual drink of each beverage at home and to measure each alcoholic beverage and other ingredients with a provided beaker. Information on the brand or type of each beverage was used to specify the percentage of alcohol. The weighted mean alcohol content of respondents' drinks was 0.67 ounces overall, 0.56 ounces for beer, 0.66 ounces for wine and 0.89 ounces for spirits. Spirits and wine drink contents were particularly variable with many high-alcohol drinks observed. While the 0.6-ounce of alcohol drink standard appears to be a reasonable single standard, it cannot capture the substantial variation evident in this sample and it underestimates average wine and spirits ethanol content. Direct measurement or beverage-specific mean ethanol content estimates would improve the precision of survey alcohol assessment.

  8. Differentiating emotions across contexts: comparing adults with and without social anxiety disorder using random, social interaction, and daily experience sampling.

    Science.gov (United States)

    Kashdan, Todd B; Farmer, Antonina S

    2014-06-01

    The ability to recognize and label emotional experiences has been associated with well-being and adaptive functioning. This skill is particularly important in social situations, as emotions provide information about the state of relationships and help guide interpersonal decisions, such as whether to disclose personal information. Given the interpersonal difficulties linked to social anxiety disorder (SAD), deficient negative emotion differentiation may contribute to impairment in this population. We hypothesized that people with SAD would exhibit less negative emotion differentiation in daily life, and these differences would translate to impairment in social functioning. We recruited 43 people diagnosed with generalized SAD and 43 healthy adults to describe the emotions they experienced over 14 days. Participants received palmtop computers for responding to random prompts and describing naturalistic social interactions; to complete end-of-day diary entries, they used a secure online website. We calculated intraclass correlation coefficients to capture the degree of differentiation of negative and positive emotions for each context (random moments, face-to-face social interactions, and end-of-day reflections). Compared to healthy controls, the SAD group exhibited less negative (but not positive) emotion differentiation during random prompts, social interactions, and (at trend level) end-of-day assessments. These differences could not be explained by emotion intensity or variability over the 14 days, or to comorbid depression or anxiety disorders. Our findings suggest that people with generalized SAD have deficits in clarifying specific negative emotions felt at a given point of time. These deficits may contribute to difficulties with effective emotion regulation and healthy social relationship functioning.

  9. Differentiating Emotions Across Contexts: Comparing Adults with and without Social Anxiety Disorder Using Random, Social Interaction, and Daily Experience Sampling

    Science.gov (United States)

    Kashdan, Todd B.; Farmer, Antonina S.

    2014-01-01

    The ability to recognize and label emotional experiences has been associated with well-being and adaptive functioning. This skill is particularly important in social situations, as emotions provide information about the state of relationships and help guide interpersonal decisions, such as whether to disclose personal information. Given the interpersonal difficulties linked to social anxiety disorder (SAD), deficient negative emotion differentiation may contribute to impairment in this population. We hypothesized that people with SAD would exhibit less negative emotion differentiation in daily life, and these differences would translate to impairment in social functioning. We recruited 43 people diagnosed with generalized SAD and 43 healthy adults to describe the emotions they experienced over 14 days. Participants received palmtop computers for responding to random prompts and describing naturalistic social interactions; to complete end-of-day diary entries, they used a secure online website. We calculated intraclass correlation coefficients to capture the degree of differentiation of negative and positive emotions for each context (random moments, face-to-face social interactions, and end-of-day reflections). Compared to healthy controls, the SAD group exhibited less negative (but not positive) emotion differentiation during random prompts, social interactions, and (at trend level) end-of-day assessments. These differences could not be explained by emotion intensity or variability over the 14 days, or to comorbid depression or anxiety disorders. Our findings suggest that people with generalized SAD have deficits in clarifying specific negative emotions felt at a given point of time. These deficits may contribute to difficulties with effective emotion regulation and healthy social relationship functioning. PMID:24512246

  10. Genetically predicted body mass index and Alzheimer's disease-related phenotypes in three large samples: Mendelian randomization analyses.

    Science.gov (United States)

    Mukherjee, Shubhabrata; Walter, Stefan; Kauwe, John S K; Saykin, Andrew J; Bennett, David A; Larson, Eric B; Crane, Paul K; Glymour, M Maria

    2015-12-01

    Observational research shows that higher body mass index (BMI) increases Alzheimer's disease (AD) risk, but it is unclear whether this association is causal. We applied genetic variants that predict BMI in Mendelian randomization analyses, an approach that is not biased by reverse causation or confounding, to evaluate whether higher BMI increases AD risk. We evaluated individual-level data from the AD Genetics Consortium (ADGC: 10,079 AD cases and 9613 controls), the Health and Retirement Study (HRS: 8403 participants with algorithm-predicted dementia status), and published associations from the Genetic and Environmental Risk for AD consortium (GERAD1: 3177 AD cases and 7277 controls). No evidence from individual single-nucleotide polymorphisms or polygenic scores indicated BMI increased AD risk. Mendelian randomization effect estimates per BMI point (95% confidence intervals) were as follows: ADGC, odds ratio (OR) = 0.95 (0.90-1.01); HRS, OR = 1.00 (0.75-1.32); GERAD1, OR = 0.96 (0.87-1.07). One subscore (cellular processes not otherwise specified) unexpectedly predicted lower AD risk. Copyright © 2015 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

  11. Family constellation seminars improve psychological functioning in a general population sample: results of a randomized controlled trial.

    Science.gov (United States)

    Weinhold, Jan; Hunger, Christina; Bornhäuser, Annette; Link, Leoni; Rochon, Justine; Wild, Beate; Schweitzer, Jochen

    2013-10-01

    The study examined the efficacy of nonrecurring family constellation seminars on psychological health. We conducted a monocentric, single-blind, stratified, and balanced randomized controlled trial (RCT). After choosing their roles for participating in a family constellation seminar as either active participant (AP) or observing participant (OP), 208 adults (M = 48 years, SD = 10; 79% women) from the general population were randomly allocated to the intervention group (IG; 3-day family constellation seminar; 64 AP, 40 OP) or a wait-list control group (WLG; 64 AP, 40 OP). It was predicted that family constellation seminars would improve psychological functioning (Outcome Questionnaire OQ-45.2) at 2-week and 4-month follow-ups. In addition, we assessed the impact of family constellation seminars on psychological distress and motivational incongruence. The IG showed significantly improved psychological functioning (d = 0.45 at 2-week follow-up, p = .003; d = 0.46 at 4-month follow-up, p = .003). Results were confirmed for psychological distress and motivational incongruence. No adverse events were reported. This RCT provides evidence for the efficacy of family constellation in a nonclinical population. The implications of the findings are discussed.

  12. Effects of delayed compared with early umbilical cord clamping on maternal postpartum hemorrhage and cord blood gas sampling: a randomized trial.

    Science.gov (United States)

    Andersson, Ola; Hellström-Westas, Lena; Andersson, Dan; Clausen, Jesper; Domellöf, Magnus

    2013-05-01

    To investigate the effect of delayed cord clamping (DCC) compared with early cord clamping (ECC) on maternal postpartum hemorrhage (PPH) and umbilical cord blood gas sampling. Secondary analysis of a parallel-group, single-center, randomized controlled trial. Swedish county hospital. 382 term deliveries after a low-risk pregnancy. Deliveries were randomized to DCC (≥180 seconds, n = 193) or ECC (≤10 seconds, n = 189). Maternal blood loss was estimated by the midwife. Samples for blood gas analysis were taken from one umbilical artery and the umbilical vein, from the pulsating unclamped cord in the DCC group and from the double-clamped cord in the ECC group. Samples were classified as valid when the arterial-venous difference was -0.02 or less for pH and 0.5 kPa or more for pCO2 . Main outcome measures. PPH and proportion of valid blood gas samples. The differences between the DCC and ECC groups with regard to PPH (1.2%, p = 0.8) and severe PPH (-2.7%, p = 0.3) were small and non-significant. The proportion of valid blood gas samples was similar between the DCC (67%, n = 130) and ECC (74%, n = 139) groups, with 6% (95% confidence interval: -4%-16%, p = 0.2) fewer valid samples after DCC. Delayed cord clamping, compared with early, did not have a significant effect on maternal postpartum hemorrhage or on the proportion of valid blood gas samples. We conclude that delayed cord clamping is a feasible method from an obstetric perspective. © 2012 The Authors Acta Obstetricia et Gynecologica Scandinavica© 2012 Nordic Federation of Societies of Obstetrics and Gynecology.

  13. Sample size determination for assessing equivalence based on proportion ratio under a randomized trial with non-compliance and missing outcomes.

    Science.gov (United States)

    Lui, Kung-Jong; Chang, Kuang-Chao

    2008-01-15

    When a generic drug is developed, it is important to assess the equivalence of therapeutic efficacy between the new and the standard drugs. Although the number of publications on testing equivalence and its relevant sample size determination is numerous, the discussion on sample size determination for a desired power of detecting equivalence under a randomized clinical trial (RCT) with non-compliance and missing outcomes is limited. In this paper, we derive under the compound exclusion restriction model the maximum likelihood estimator (MLE) for the ratio of probabilities of response among compliers between two treatments in a RCT with both non-compliance and missing outcomes. Using the MLE with the logarithmic transformation, we develop an asymptotic test procedure for assessing equivalence and find that this test procedure can perform well with respect to type I error based on Monte Carlo simulation. We further develop a sample size calculation formula for a desired power of detecting equivalence at a nominal alpha-level. To evaluate the accuracy of the sample size calculation formula, we apply Monte Carlo simulation again to calculate the simulated power of the proposed test procedure corresponding to the resulting sample size for a desired power of 80 per cent at 0.05 level in a variety of situations. We also include a discussion on determining the optimal ratio of sample size allocation subject to a desired power to minimize a linear cost function and provide a sensitivity analysis of the sample size formula developed here under an alterative model with missing at random. Copyright (c) 2007 John Wiley & Sons, Ltd.

  14. Variance results for the second and third reduced sample moments in neutron multiplicity counting for randomly triggered or signal-triggered counting gates

    Energy Technology Data Exchange (ETDEWEB)

    Burr, T. [Statistical Sciences Group, Los Alamos National Laboratory, Mail Stop F600, Los Alamos, NM 87545 (United States)], E-mail: tburr@lanl.gov; Butterfield, K. [Advanced Nuclear Technology Group, Los Alamos National Laboratory, Mail Stop F600, Los Alamos, NM 87545 (United States)

    2008-09-01

    Neutron multiplicity counting is an established method to estimate the spontaneous fission rate, and therefore also the plutonium mass for example, in a sample that includes other neutron sources. The extent to which the sample and detector obey the 'point model' assumptions impacts the estimate's total measurement error, but, in nearly all cases, for the random error contribution, it is useful to evaluate the variances of the second and third reduced sample moments of the neutron source strength. Therefore, this paper derives exact expressions for the variances and covariances of the second and third reduced sample moments for either randomly triggered or signal-triggered non-overlapping counting gates, and compares them to the corresponding variances in simulated data. Approximate expressions are also provided for the case of overlapping counting gates. These variances and covariances are useful in figure of merit calculations to predict assay performance prior to data collection. In addition, whenever real data are available, a bootstrap method is presented as an alternate but effective way to estimate these variances.

  15. A double-blind randomized controlled trial to study the efficacy of topiramate in a civilian sample of PTSD.

    Science.gov (United States)

    Yeh, Mary S L; Mari, Jair Jesus; Costa, Mariana Caddrobi Pupo; Andreoli, Sergio Baxter; Bressan, Rodrigo Affonseca; Mello, Marcelo Feijó

    2011-10-01

    To evaluate the efficacy and tolerability of topiramate in patients with posttraumatic stress disorder (PTSD). We conducted a 12-week double-blind, randomized, placebo-controlled study comparing topiramate to placebo. Men and women aged 18-62 years with diagnosis of PTSD according to DSM-IV were recruited from the outpatient clinic of the violence program of Federal University of São Paulo Hospital (Prove-UNIFESP), São Paulo City, between April 2006 and December 2009. Subjects were assessed for the Clinician-Administered Posttraumatic Stress Scale (CAPS), Clinical Global Impression, and Beck Depression Inventory (BDI). After 1-week period of washout, 35 patients were randomized to either group. The primary outcome measure was the CAPS total score changes from baseline to the endpoint. 82.35% of patients in the topiramate group exhibited improvements in PTSD symptoms. The efficacy analysis demonstrated that patients in the topiramate group exhibited significant improvements in reexperiencing symptoms: flashbacks, intrusive memories, and nightmares of the trauma (CAPS-B; P= 0.04) and in avoidance/numbing symptoms associated with the trauma, social isolation, and emotional numbing (CAPS-C; P= 0.0001). Furthermore, the experimental group demonstrated a significant difference in decrease in CAPS total score (topiramate -57.78; placebo -32.41; P= 0.0076). Mean topiramate dose was 102.94 mg/d. Topiramate was generally well tolerated. Topiramate was effective in improving reexperiencing and avoidance/numbing symptom clusters in patients with PTSD. This study supports the use of anticonvulsants for the improvement of symptoms of PTSD. © 2010 Blackwell Publishing Ltd.

  16. An econometric method for estimating population parameters from non-random samples: An application to clinical case finding.

    Science.gov (United States)

    Burger, Rulof P; McLaren, Zoë M

    2017-09-01

    The problem of sample selection complicates the process of drawing inference about populations. Selective sampling arises in many real world situations when agents such as doctors and customs officials search for targets with high values of a characteristic. We propose a new method for estimating population characteristics from these types of selected samples. We develop a model that captures key features of the agent's sampling decision. We use a generalized method of moments with instrumental variables and maximum likelihood to estimate the population prevalence of the characteristic of interest and the agents' accuracy in identifying targets. We apply this method to tuberculosis (TB), which is the leading infectious disease cause of death worldwide. We use a national database of TB test data from South Africa to examine testing for multidrug resistant TB (MDR-TB). Approximately one quarter of MDR-TB cases was undiagnosed between 2004 and 2010. The official estimate of 2.5% is therefore too low, and MDR-TB prevalence is as high as 3.5%. Signal-to-noise ratios are estimated to be between 0.5 and 1. Our approach is widely applicable because of the availability of routinely collected data and abundance of potential instruments. Using routinely collected data to monitor population prevalence can guide evidence-based policy making. Copyright © 2017 John Wiley & Sons, Ltd.

  17. Purposive versus random sampling for map validation: a case study on ecotope maps of floodplains in the Netherlands

    NARCIS (Netherlands)

    Knotters, M.; Brus, D.J.

    2013-01-01

    The quality of ecotope maps of five districts of main water courses in the Netherlands was assessed on the basis of independent validation samples of field observations. The overall proportion of area correctly classified, and user's and producer's accuracy for each map unit were estimated. In four

  18. Estimation of the Box Correction for Degrees of Freedom from Sample Data in Randomized Block and Split-Plot Designs

    Science.gov (United States)

    Huynh, Huynh; Feldt, Leonard S.

    1976-01-01

    When the variance assumptions of a repeated measures ANOVA are not met, the F distribution of the mean square ratio should be adjusted by the sample estimate of the Box correction factor. An alternative is proposed which is shown by Monte Carlo methods to be less biased for a moderately large factor. (RC)

  19. Randomized controlled trial of endoscopic ultrasound-guided fine-needle sampling with or without suction for better cytological diagnosis

    DEFF Research Database (Denmark)

    Puri, Rajesh; Vilmann, Peter; Saftoiu, Adrian

    2009-01-01

    ). The samples were characterized for cellularity and bloodiness, with a final cytology diagnosis established blindly. The final diagnosis was reached either by EUS-FNA if malignancy was definite, or by surgery and/or clinical follow-up of a minimum of 6 months in the cases of non-specific benign lesions...

  20. HPV self-sampling or the Pap-smear: a randomized study among cervical screening nonattenders from lower socioeconomic groups in France.

    Science.gov (United States)

    Sancho-Garnier, H; Tamalet, C; Halfon, P; Leandri, F X; Le Retraite, L; Djoufelkit, K; Heid, P; Davies, P; Piana, L

    2013-12-01

    Today in France, low attendance to cervical screening by Papanicolaou cytology (Pap-smear) is a major contributor to the 3,000 new cervical cancer cases and 1,000 deaths that occur from this disease every year. Nonattenders are mostly from lower socioeconomic groups and testing of self-obtained samples for high-risk Human Papilloma virus (HPV) types has been proposed as a method to increase screening participation in these groups. In 2011, we conducted a randomized study of women aged 35-69 from very low-income populations around Marseille who had not responded to an initial invitation for a free Pap-smear. After randomization, one group received a second invitation for a free Pap-smear and the other group was offered a free self-sampling kit for HPV testing. Participation rates were significantly different between the two groups with only 2.0% of women attending for a Pap-smear while 18.3% of women returned a self-sample for HPV testing (p ≤ 0.001). The detection rate of high-grade lesions (≥CIN2) was 0.2‰ in the Pap-smear group and 1.25‰ in the self-sampling group (p = 0.01). Offering self-sampling increased participation rates while the use of HPV testing increased the detection of cervical lesions (≥CIN2) in comparison to the group of women receiving a second invitation for a Pap-smear. However, low compliance to follow-up in the self-sampling group reduces the effectiveness of this screening approach in nonattenders women and must be carefully managed. Copyright © 2013 UICC.

  1. Control charts for location based on different sampling schemes

    NARCIS (Netherlands)

    Mehmood, R.; Riaz, M.; Does, R.J.M.M.

    2013-01-01

    Control charts are the most important statistical process control tool for monitoring variations in a process. A number of articles are available in the literature for the X̄ control chart based on simple random sampling, ranked set sampling, median-ranked set sampling (MRSS), extreme-ranked set

  2. Is the timing of caloric intake associated with variation in diet-induced thermogenesis and in the metabolic pattern? A randomized cross-over study.

    Science.gov (United States)

    Bo, S; Fadda, M; Castiglione, A; Ciccone, G; De Francesco, A; Fedele, D; Guggino, A; Parasiliti Caprino, M; Ferrara, S; Vezio Boggio, M; Mengozzi, G; Ghigo, E; Maccario, M; Broglio, F

    2015-12-01

    Food-induced thermogenesis is generally reported to be higher in the morning, although contrasting results exist because of differences in experimental settings related to the preceding fasting, exercise, sleeping and dieting. To definitively answer to this issue, we compared the calorimetric and metabolic responses to identical meals consumed at 0800 hours and at 2000 hours by healthy volunteers, after standardized diet, physical activity, duration of fast and resting. Twenty subjects (age range 20-35 years, body mass index=19-26 kg m(-)(2)) were enrolled to a randomized cross-over trial. They randomly received the same standard meal in the morning and, 7 days after, in the evening, or vice versa. A 30-min basal calorimetry was performed; a further 60-min calorimetry was done 120-min after the beginning of the meal. Blood samples were drawn every 30-min for 180-min. General linear models, adjusted for period and carry-over, were used to evaluate the 'morning effect', that is, the difference of morning delta (after-meal minus fasting values) minus evening delta (after-meal minus fasting values) of the variables. Fasting resting metabolic rate (RMR) did not change from morning to evening; after-meal RMR values were significantly higher after the morning meal (1916; 95% confidence interval (CI)=1792, 2041 vs 1756; 1648, 1863 kcal; Pmetabolic pattern of healthy individuals. The timing of meals should probably be considered when nutritional recommendations are given.

  3. Aerobic physical activity and resistance training: an application of the theory of planned behavior among adults with type 2 diabetes in a random, national sample of Canadians

    Directory of Open Access Journals (Sweden)

    Karunamuni Nandini

    2008-12-01

    Full Text Available Abstract Background Aerobic physical activity (PA and resistance training are paramount in the treatment and management of type 2 diabetes (T2D, but few studies have examined the determinants of both types of exercise in the same sample. Objective The primary purpose was to investigate the utility of the Theory of Planned Behavior (TPB in explaining aerobic PA and resistance training in a population sample of T2D adults. Methods A total of 244 individuals were recruited through a random national sample which was created by generating a random list of household phone numbers. The list was proportionate to the actual number of household telephone numbers for each Canadian province (with the exception of Quebec. These individuals completed self-report TPB constructs of attitude, subjective norm, perceived behavioral control and intention, and a 3-month follow-up that assessed aerobic PA and resistance training. Results TPB explained 10% and 8% of the variance respectively for aerobic PA and resistance training; and accounted for 39% and 45% of the variance respectively for aerobic PA and resistance training intentions. Conclusion These results may guide the development of appropriate PA interventions for aerobic PA and resistance training based on the TPB.

  4. How precise is the finite sample approximation of the asymptotic distribution of realised variation measures in the presence of jumps?

    DEFF Research Database (Denmark)

    Veraart, Almut

    2011-01-01

    This paper studies the impact of jumps on volatility estimation and inference based on various realised variation measures such as realised variance, realised multipower variation and truncated realised multipower variation. We review the asymptotic theory of those realised variation measures and...... of a highly active jump process. Finally, we investigate the impact of jumps on inference on volatility empirically, where we study high frequency data from the Standard & Poor’s Depository Receipt (SPY)....

  5. A cluster-randomized trial of a middle school gender violence prevention program: Design, rationale, and sample characteristics.

    Science.gov (United States)

    Abebe, Kaleab Z; Jones, Kelley A; Ciaravino, Samantha; Ripper, Lisa; Paglisotti, Taylor; Morrow, Sarah Elizabeth; Grafals, Melanie; Van Dusen, Courtney; Miller, Elizabeth

    2017-11-01

    High rates of adolescent relationship abuse (ARA) and sexual violence (SV) reported among adolescents point to the need for prevention among middle school-age youth. This is a cluster randomized controlled trial to test an athletic coach-delivered ARA/SV prevention program in 41 middle schools (38 clusters). Trained coaches talk to their male athletes about 1) what constitutes harmful vs. respectful relationship behaviors, 2) dispelling myths that glorify male sexual aggression and promoting more gender-equitable attitudes, and 3) positive bystander intervention when aggressive male behaviors toward females are witnessed. A total of 973 male athletes (ages 11-14, grades 6-8) are participating. Athletes complete surveys at the beginning and end of sports season (Time 2), and one year later (Time 3). The primary outcome is an increase in positive bystander behaviors (i.e., intervening in peers' disrespectful or harmful behaviors); secondary outcomes are changes in recognition of what constitutes abusive behavior, intentions to intervene, and gender equitable attitudes (Time 2 and 3) as well as reduction in abuse perpetration (Time 3). Participating schools have a greater proportion of non-White students and students on free/reduced lunch compared to schools that declined participation. Participants' self-reported ethnicities are 54.5% White, 29.0% Black, 1.4% Hispanic and the remainder, multi-racial, other, or not reported. This study will evaluate the effectiveness of a coach-delivered ARA/SV prevention program for middle school male athletes. Findings will add to the evidence base regarding developmentally appropriate violence prevention programs as well as the role of coaches in adolescent health promotion. Clinical Trials #: NCT02331238. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  6. Reducing eating disorder onset in a very high risk sample with significant comorbid depression: A randomized controlled trial.

    Science.gov (United States)

    Taylor, C Barr; Kass, Andrea E; Trockel, Mickey; Cunning, Darby; Weisman, Hannah; Bailey, Jakki; Sinton, Meghan; Aspen, Vandana; Schecthman, Kenneth; Jacobi, Corinna; Wilfley, Denise E

    2016-05-01

    Eating disorders (EDs) are serious problems among college-age women and may be preventable. An indicated online eating disorder (ED) intervention, designed to reduce ED and comorbid pathology, was evaluated. 206 women (M age = 20 ± 1.8 years; 51% White/Caucasian, 11% African American, 10% Hispanic, 21% Asian/Asian American, 7% other) at very high risk for ED onset (i.e., with high weight/shape concerns plus a history of being teased, current or lifetime depression, and/or nonclinical levels of compensatory behaviors) were randomized to a 10-week, Internet-based, cognitive-behavioral intervention or waitlist control. Assessments included the Eating Disorder Examination (EDE, to assess ED onset), EDE-Questionnaire, Structured Clinical Interview for DSM Disorders, and Beck Depression Inventory-II. ED attitudes and behaviors improved more in the intervention than control group (p = .02, d = 0.31); although ED onset rate was 27% lower, this difference was not significant (p = .28, NNT = 15). In the subgroup with highest shape concerns, ED onset rate was significantly lower in the intervention than control group (20% vs. 42%, p = .025, NNT = 5). For the 27 individuals with depression at baseline, depressive symptomatology improved more in the intervention than control group (p = .016, d = 0.96); although ED onset rate was lower in the intervention than control group, this difference was not significant (25% vs. 57%, NNT = 4). An inexpensive, easily disseminated intervention might reduce ED onset among those at highest risk. Low adoption rates need to be addressed in future research. (c) 2016 APA, all rights reserved).

  7. High Throughput qPCR Expression Profiling of Circulating MicroRNAs Reveals Minimal Sex- and Sample Timing-Related Variation in Plasma of Healthy Volunteers.

    Science.gov (United States)

    Mooney, Catherine; Raoof, Rana; El-Naggar, Hany; Sanz-Rodriguez, Amaya; Jimenez-Mateos, Eva M; Henshall, David C

    2015-01-01

    MicroRNAs are a class of small non-coding RNA that regulate gene expression at a post-transcriptional level. MicroRNAs have been identified in various body fluids under normal conditions and their stability as well as their dysregulation in disease opens up a new field for biomarker study. However, diurnal and day-to-day variation in plasma microRNA levels, and differential regulation between males and females, may affect biomarker stability. A QuantStudio 12K Flex Real-Time PCR System was used to profile plasma microRNA levels using OpenArray in male and female healthy volunteers, in the morning and afternoon, and at four time points over a one month period. Using this system we were able to run four OpenArray plates in a single run, the equivalent of 32 traditional 384-well qPCR plates or 12,000 data points. Up to 754 microRNAs can be identified in a single plasma sample in under two hours. 108 individual microRNAs were identified in at least 80% of all our samples which compares favourably with other reports of microRNA profiles in serum or plasma in healthy adults. Many of these microRNAs, including miR-16-5p, miR-17-5p, miR-19a-3p, miR-24-3p, miR-30c-5p, miR-191-5p, miR-223-3p and miR-451a are highly expressed and consistent with previous studies using other platforms. Overall, microRNA levels were very consistent between individuals, males and females, and time points and we did not detect significant differences in levels of microRNAs. These results suggest the suitability of this platform for microRNA profiling and biomarker discovery and suggest minimal confounding influence of sex or sample timing. However, the platform has not been subjected to rigorous validation which must be demonstrated in future biomarker studies where large differences may exist between disease and control samples.

  8. High Throughput qPCR Expression Profiling of Circulating MicroRNAs Reveals Minimal Sex- and Sample Timing-Related Variation in Plasma of Healthy Volunteers.

    Directory of Open Access Journals (Sweden)

    Catherine Mooney

    Full Text Available MicroRNAs are a class of small non-coding RNA that regulate gene expression at a post-transcriptional level. MicroRNAs have been identified in various body fluids under normal conditions and their stability as well as their dysregulation in disease opens up a new field for biomarker study. However, diurnal and day-to-day variation in plasma microRNA levels, and differential regulation between males and females, may affect biomarker stability. A QuantStudio 12K Flex Real-Time PCR System was used to profile plasma microRNA levels using OpenArray in male and female healthy volunteers, in the morning and afternoon, and at four time points over a one month period. Using this system we were able to run four OpenArray plates in a single run, the equivalent of 32 traditional 384-well qPCR plates or 12,000 data points. Up to 754 microRNAs can be identified in a single plasma sample in under two hours. 108 individual microRNAs were identified in at least 80% of all our samples which compares favourably with other reports of microRNA profiles in serum or plasma in healthy adults. Many of these microRNAs, including miR-16-5p, miR-17-5p, miR-19a-3p, miR-24-3p, miR-30c-5p, miR-191-5p, miR-223-3p and miR-451a are highly expressed and consistent with previous studies using other platforms. Overall, microRNA levels were very consistent between individuals, males and females, and time points and we did not detect significant differences in levels of microRNAs. These results suggest the suitability of this platform for microRNA profiling and biomarker discovery and suggest minimal confounding influence of sex or sample timing. However, the platform has not been subjected to rigorous validation which must be demonstrated in future biomarker studies where large differences may exist between disease and control samples.

  9. Photo anthropometric variations in Japanese facial features: Establishment of large-sample standard reference data for personal identification using a three-dimensional capture system.

    Science.gov (United States)

    Ogawa, Y; Wada, B; Taniguchi, K; Miyasaka, S; Imaizumi, K

    2015-12-01

    This study clarifies the anthropometric variations of the Japanese face by presenting large-sample population data of photo anthropometric measurements. The measurements can be used as standard reference data for the personal identification of facial images in forensic practices. To this end, three-dimensional (3D) facial images of 1126 Japanese individuals (865 male and 261 female Japanese individuals, aged 19-60 years) were acquired as samples using an already validated 3D capture system, and normative anthropometric analysis was carried out. In this anthropometric analysis, first, anthropological landmarks (22 items, i.e., entocanthion (en), alare (al), cheilion (ch), zygion (zy), gonion (go), sellion (se), gnathion (gn), labrale superius (ls), stomion (sto), labrale inferius (li)) were positioned on each 3D facial image (the direction of which had been adjusted to the Frankfort horizontal plane as the standard position for appropriate anthropometry), and anthropometric absolute measurements (19 items, i.e., bientocanthion breadth (en-en), nose breadth (al-al), mouth breadth (ch-ch), bizygomatic breadth (zy-zy), bigonial breadth (go-go), morphologic face height (se-gn), upper-lip height (ls-sto), lower-lip height (sto-li)) were exported using computer software for the measurement of a 3D digital object. Second, anthropometric indices (21 items, i.e., (se-gn)/(zy-zy), (en-en)/(al-al), (ls-li)/(ch-ch), (ls-sto)/(sto-li)) were calculated from these exported measurements. As a result, basic statistics, such as the mean values, standard deviations, and quartiles, and details of the distributions of these anthropometric results were shown. All of the results except "upper/lower lip ratio (ls-sto)/(sto-li)" were normally distributed. They were acquired as carefully as possible employing a 3D capture system and 3D digital imaging technologies. The sample of images was much larger than any Japanese sample used before for the purpose of personal identification. The

  10. Novel approach to systematic random sampling in population surveys: Lessons from the United Arab Emirates National Diabetes Study (UAEDIAB).

    Science.gov (United States)

    Sulaiman, Nabil; Albadawi, Salah; Abusnana, Salah; Fikri, Mahmoud; Madani, Abdulrazzag; Mairghani, Maisoon; Alawadi, Fatheya; Zimmet, Paul; Shaw, Jonathan

    2015-09-01

    The prevalence of diabetes has risen rapidly in the Middle East, particularly in the Gulf Region. However, some prevalence estimates have not fully accounted for large migrant worker populations and have focused on minority indigenous populations. The objectives of the UAE National Diabetes and Lifestyle Study are to: (i) define the prevalence of, and risk factors for, T2DM; (ii) describe the distribution and determinants of T2DM risk factors; (iii) study health knowledge, attitudes, and (iv) identify gene-environment interactions; and (v) develop baseline data for evaluation of future intervention programs. Given the high burden of diabetes in the region and the absence of accurate data on non-UAE nationals in the UAE, a representative sample of the non-UAE nationals was essential. We used an innovative methodology in which non-UAE nationals were sampled when attending the mandatory biannual health check that is required for visa renewal. Such an approach could also be used in other countries in the region. Complete data were available for 2719 eligible non-UAE nationals (25.9% Arabs, 70.7% Asian non-Arabs, 1.1% African non-Arabs, and 2.3% Westerners). Most were men service and sales, and unskilled occupations. Most (37.4%) had completed high school and 4.1% had a postgraduate degree. This novel methodology could provide insights for epidemiological studies in the UAE and other Gulf States, particularly for expatriates. © 2015 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

  11. Two to five repeated measurements per patient reduced the required sample size considerably in a randomized clinical trial for patients with inflammatory rheumatic diseases

    Directory of Open Access Journals (Sweden)

    Smedslund Geir

    2013-02-01

    Full Text Available Abstract Background Patient reported outcomes are accepted as important outcome measures in rheumatology. The fluctuating symptoms in patients with rheumatic diseases have serious implications for sample size in clinical trials. We estimated the effects of measuring the outcome 1-5 times on the sample size required in a two-armed trial. Findings In a randomized controlled trial that evaluated the effects of a mindfulness-based group intervention for patients with inflammatory arthritis (n=71, the outcome variables Numerical Rating Scales (NRS (pain, fatigue, disease activity, self-care ability, and emotional wellbeing and General Health Questionnaire (GHQ-20 were measured five times before and after the intervention. For each variable we calculated the necessary sample sizes for obtaining 80% power (α=.05 for one up to five measurements. Two, three, and four measures reduced the required sample sizes by 15%, 21%, and 24%, respectively. With three (and five measures, the required sample size per group was reduced from 56 to 39 (32 for the GHQ-20, from 71 to 60 (55 for pain, 96 to 71 (73 for fatigue, 57 to 51 (48 for disease activity, 59 to 44 (45 for self-care, and 47 to 37 (33 for emotional wellbeing. Conclusions Measuring the outcomes five times rather than once reduced the necessary sample size by an average of 27%. When planning a study, researchers should carefully compare the advantages and disadvantages of increasing sample size versus employing three to five repeated measurements in order to obtain the required statistical power.

  12. Heuristic Relative Entropy Principles with Complex Measures: Large-Degree Asymptotics of a Family of Multi-variate Normal Random Polynomials

    Science.gov (United States)

    Kiessling, Michael Karl-Heinz

    2017-10-01

    Let z\\in C, let σ ^2>0 be a variance, and for N\\in N define the integrals E_N^{}(z;σ ) := {1/σ } \\int _R\\ (x^2+z^2) e^{-{1/2σ^2 x^2}}{√{2π }}/dx \\quad if N=1, {1/σ } \\int _{R^N} \\prod \\prod \\limits _{1≤ k1. These are expected values of the polynomials P_N^{}(z)=\\prod _{1≤ n≤ N}(X_n^2+z^2) whose 2 N zeros ± i X_k^{}_{k=1,\\ldots ,N} are generated by N identically distributed multi-variate mean-zero normal random variables {X_k}N_{k=1} with co-variance {Cov}_N^{}(X_k,X_l)=(1+σ ^2-1/N)δ _{k,l}+σ ^2-1/N(1-δ _{k,l}). The E_N^{}(z;σ ) are polynomials in z^2, explicitly computable for arbitrary N, yet a list of the first three E_N^{}(z;σ ) shows that the expressions become unwieldy already for moderate N—unless σ = 1, in which case E_N^{}(z;1) = (1+z^2)^N for all z\\in C and N\\in N. (Incidentally, commonly available computer algebra evaluates the integrals E_N^{}(z;σ ) only for N up to a dozen, due to memory constraints). Asymptotic evaluations are needed for the large- N regime. For general complex z these have traditionally been limited to analytic expansion techniques; several rigorous results are proved for complex z near 0. Yet if z\\in R one can also compute this "infinite-degree" limit with the help of the familiar relative entropy principle for probability measures; a rigorous proof of this fact is supplied. Computer algebra-generated evidence is presented in support of a conjecture that a generalization of the relative entropy principle to signed or complex measures governs the N→ ∞ asymptotics of the regime iz\\in R. Potential generalizations, in particular to point vortex ensembles and the prescribed Gauss curvature problem, and to random matrix ensembles, are emphasized.

  13. Missing citations due to exact reference matching: Analysis of a random sample from WoS. Are publications from peripheral countries disadvantaged?

    Energy Technology Data Exchange (ETDEWEB)

    Donner, P.

    2016-07-01

    Citation counts of scientific research contributions are one fundamental data in scientometrics. Accuracy and completeness of citation links are therefore crucial data quality issues (Moed, 2005, Ch. 13). However, despite the known flaws of reference matching algorithms, usually no attempts are made to incorporate uncertainty about citation counts into indicators. This study is a step towards that goal. Particular attention is paid to the question whether publications from countries not using basic Latin script are differently affected by missed citations. The proprietary reference matching procedure of Web of Science (WoS) is based on (near) exact agreement of cited reference data (normalized during processing) to the target papers bibliographical data. Consequently, the procedure has near-optimal precision but incomplete recall - it is known to miss some slightly inaccurate reference links (Olensky, 2015). However, there has been no attempt so far to estimate the rate of missed citations by a principled method for a random sample. For this study a simple random sample of WoS source papers was drawn and it was attempted to find all reference strings of WoS indexed documents that refer to them, in particular inexact matches. The objective is to give a statistical estimate of the proportion of missed citations and to describe the relationship of the number of found citations to the number of missed citations, i.e. the conditional error distribution. The empirical error distribution is statistically analyzed and modelled. (Author)

  14. [VARIATION ON SOMATOTYPE AND WAIST CIRCUMFERENCE IN A SAMPLE OF UNIVERSITY STUDENTS BETWEEN YEARS 2012 AND 2014 IN THE TEMUCO, CHILE].

    Science.gov (United States)

    Carrasco Alarcón, Vanessa; Martínez Salazar, Cristian; Álvarez Lepín, Cristian; Jorquera Aguilera, Carlos; Aguilar Farías, Nicolás

    2015-07-01

    Objetive: to determine variation on somatotype and waist circumference (WC) in university students during a three-year follow-up. a total sample of 36 first-year university students was recruited in 2012. Heath-Carter anthropometric somatotype and waist circumference were assessed in 2012 and 2014. male students showed mesomorph component (3.7-5.3-1.8) as dominant in 2012, while in 2014 endomorph and mesomorph components were equal (4.1-4.5-1.6). The somatotype in female students was dominated by endomorphic component in 2012 (5.4-4.6-1.7) and 2014 (5.3-3.2-1.6). Among somatotypes, for both, male and female students, only endomorphy showed statistically significant differences during the follow-up (p = 0,00). The endo-mesomorphic somatotype was dominant in men with 61.9% in 2012 and 38.1% in 2014. Women showed a higher percentage for meso-endomorphic somatotype with 60% in 2012 and 80% in 2014. In men, WC between 2014 and 2014 showed a statistically significant increment of 4.8% (p = 0,00). In women WC increased by 13.3% but no statistically difference was observed (p = 0,10). this study showed somatotypic change with tendency in increased endomorphy in both men and women. Despite WC values were similar to the national mean, cases with cardiometabolic risk increased during the follow-up period based on this measurement. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

  15. Spatial and seasonal variations of pesticide contamination in agricultural soils and crops sample from an intensive horticulture area of Hohhot, North-West China.

    Science.gov (United States)

    Zhang, Fujin; He, Jiang; Yao, Yiping; Hou, Dekun; Jiang, Cai; Zhang, Xinxin; Di, Caixia; Otgonbayar, Khureldavaa

    2013-08-01

    The spatial variability and temporal trend in concentrations of the organochlorine pesticides (OCPs), hexachlorocyclohexane (HCH) and dichlorodiphenyltrichloroethane (DDT), in soils and agricultural corps were investigated on an intensive horticulture area in Hohhot, North-West China, from 2008 to 2011. The most frequently found and abundant pesticides were the metabolites of DDT (p,p'-DDE, p,p'-DDT, o,p'-DDT and p,p'-DDD). Total DDT concentrations ranged from ND (not detectable) to 507.41 ng/g and were higher than the concentration of total HCHs measured for the range of 4.84-281.44 ng/g. There were significantly positive correlations between the ∑DDT and ∑HCH concentrations (r (2)>0.74) in soils, but no significant correlation was found between the concentrations of OCPs in soils and clay content while a relatively strong correlation was found between total OCP concentrations and total organic carbon (TOC). β-HCH was the main isomer of HCHs, and was detected in all samples; the maximum proportion of β-HCH compared to ∑HCHs (mean value 54%) was found, suggesting its persistence. The α/γ-HCH ratio was between 0.89 and 5.39, which signified the combined influence of technical HCHs and lindane. Low p,p'-DDE/p,p'-DDT in N1, N3 and N9 were found, reflecting the fresh input of DDTs, while the relatively high o,p'-DDT/p,p'-DDT ratios indicated the agricultural application of dicofol. Ratios of DDT/(DDE+DDD) in soils do not indicate recent inputs of DDT into Hohhot farmland soil environment. Seasonal variations of OCPs featured higher concentrations in autumn and lower concentrations in spring. This was likely associated with their temperature-driven re-volatilization and application of dicofol in late spring.

  16. Validity of protein-osmolality versus protein-creatinine ratios in the estimation of quantitative proteinuria from random samples of urine in children.

    Science.gov (United States)

    Morgenstern, Bruce Z; Butani, Lavjay; Wollan, Peter; Wilson, David M; Larson, Timothy S

    2003-04-01

    Proteinuria is an important marker of kidney disease. Simple methods to determine the presence of proteinuria in a semiquantitative fashion require measurement of either a protein-creatinine or protein-osmolality ratio. Urine samples from 134 healthy infants and children and 150 children from the pediatric nephrology practice were analyzed to develop normative data for protein-osmolality ratios on random urine samples and compare protein-osmolality with protein-creatinine ratio as a predictor of 24-hour urine protein excretion. Children were grouped according to age. Three groups were established: infants (protein excretion was determined to be a protein-osmolality ratio of 0.15 mg x kg H2O/mOsm. L; for children between 2 and 8 years old, 0.14; and for children older than 8 years, 0.17 (P = not significant between age groups). The corresponding optimal cutoff value for protein-creatinine ratio for the entire group of children older than 2 years is 0.20. Area under the curve analysis of receiver operator characteristic curves showed protein-creatinine ratio was superior to protein-osmolality ratio for predicting abnormal amounts of proteinuria in children and adolescents (P protein-creatinine ratio in children, it would be appropriate to screen urine samples for proteinuria using protein-creatinine ratio rather than protein-osmolality ratio.

  17. Changes in brain volume and cognition in a randomized trial of exercise and social interaction in a community-based sample of non-demented Chinese elders.

    Science.gov (United States)

    Mortimer, James A; Ding, Ding; Borenstein, Amy R; DeCarli, Charles; Guo, Qihao; Wu, Yougui; Zhao, Qianhua; Chu, Shugang

    2012-01-01

    Physical exercise has been shown to increase brain volume and improve cognition in randomized trials of non-demented elderly. Although greater social engagement was found to reduce dementia risk in observational studies, randomized trials of social interventions have not been reported. A representative sample of 120 elderly from Shanghai, China was randomized to four groups (Tai Chi, Walking, Social Interaction, No Intervention) for 40 weeks. Two MRIs were obtained, one before the intervention period, the other after. A neuropsychological battery was administered at baseline, 20 weeks, and 40 weeks. Comparison of changes in brain volumes in intervention groups with the No Intervention group were assessed by t-tests. Time-intervention group interactions for neuropsychological measures were evaluated with repeated-measures mixed models. Compared to the No Intervention group, significant increases in brain volume were seen in the Tai Chi and Social Intervention groups (p < 0.05). Improvements also were observed in several neuropsychological measures in the Tai Chi group, including the Mattis Dementia Rating Scale score (p = 0.004), the Trailmaking Test A (p = 0.002) and B (p = 0.0002), the Auditory Verbal Learning Test (p = 0.009), and verbal fluency for animals (p = 0.01). The Social Interaction group showed improvement on some, but fewer neuropsychological indices. No differences were observed between the Walking and No Intervention groups. The findings differ from previous clinical trials in showing increases in brain volume and improvements in cognition with a largely non-aerobic exercise (Tai Chi). In addition, intellectual stimulation through social interaction was associated with increases in brain volume as well as with some cognitive improvements.

  18. Why choose Random Forest to predict rare species distribution with few samples in large undersampled areas? Three Asian crane species models provide supporting evidence

    Directory of Open Access Journals (Sweden)

    Chunrong Mi

    2017-01-01

    Full Text Available Species distribution models (SDMs have become an essential tool in ecology, biogeography, evolution and, more recently, in conservation biology. How to generalize species distributions in large undersampled areas, especially with few samples, is a fundamental issue of SDMs. In order to explore this issue, we used the best available presence records for the Hooded Crane (Grus monacha, n = 33, White-naped Crane (Grus vipio, n = 40, and Black-necked Crane (Grus nigricollis, n = 75 in China as three case studies, employing four powerful and commonly used machine learning algorithms to map the breeding distributions of the three species: TreeNet (Stochastic Gradient Boosting, Boosted Regression Tree Model, Random Forest, CART (Classification and Regression Tree and Maxent (Maximum Entropy Models. In addition, we developed an ensemble forecast by averaging predicted probability of the above four models results. Commonly used model performance metrics (Area under ROC (AUC and true skill statistic (TSS were employed to evaluate model accuracy. The latest satellite tracking data and compiled literature data were used as two independent testing datasets to confront model predictions. We found Random Forest demonstrated the best performance for the most assessment method, provided a better model fit to the testing data, and achieved better species range maps for each crane species in undersampled areas. Random Forest has been generally available for more than 20 years and has been known to perform extremely well in ecological predictions. However, while increasingly on the rise, its potential is still widely underused in conservation, (spatial ecological applications and for inference. Our results show that it informs ecological and biogeographical theories as well as being suitable for conservation applications, specifically when the study area is undersampled. This method helps to save model-selection time and effort, and allows robust and rapid

  19. In vivo photoacoustic mouse eye imaging of healing after chemical injury and automated eyeball surface estimation based on a random sample consensus algorithm

    Science.gov (United States)

    Jeon, Seungwan; Song, Hyun Beom; Kim, Jaewoo; Lee, Byung Joo; Kim, Jeong Hun; Kim, Chulhong

    2017-03-01

    Ocular chemical damage may induce limbal vessel ischemia and neovascularization, but the pathophysiology of the disease is not completely known. To observe changes in blood vessels after alkaline burn, we monitored the anterior segment and choroidal vasculature using a photoacoustic microscope (OR-PAM). We were able to observe not only the iris blood vessels but also the choroidal vessels under the sclera, which were difficult to be observed with conventional photographs. After alkali burning, we observed neovascularization and limbal ischemia and successfully tracked changes in vasculature during the 7-day healing process. We also used the RANdom SAmple Consensus (RANSAC) method to segment the abnormally generated blood vessels in the cornea by detecting the eyeball surface and successfully visualize the distance from each PA signal to the center of the eye. We believe that photoacoustic imaging has an important potential to reveal the pathophysiology of limb ischemia and neovascularization.

  20. Access to medical care among persons with musculoskeletal conditions. A study using a random sample of households in San Mateo County, California.

    Science.gov (United States)

    Yelin, E; Bernhard, G; Pflugrad, D

    1995-08-01

    To study access to medical care services, including subspecialty care, among persons with musculoskeletal conditions. In early 1993, a random sample of households in San Mateo County, California, was screened for the presence of household members with musculoskeletal conditions, and a member of each household so identified was administered a structured survey about access to medical care and other related subjects. Eighty-six percent of all persons with a musculoskeletal condition had ever seen at least one physician for the condition, but only 6.5% had ever seen a rheumatologist. Those without health insurance were only 82% as likely as those with health insurance to have ever seen a physician. Most persons with a musculoskeletal condition have seen a physician for the condition, but lack of health insurance significantly reduces the proportion who have done so.

  1. Goal-directed fluid restriction using stroke volume variation and cardiac index during one-lung ventilation: a randomized controlled trial.

    Science.gov (United States)

    Xu, Hui; Shu, Shu-Hua; Wang, Di; Chai, Xiao-Qing; Xie, Yan-Hu; Zhou, Wei-De

    2017-09-01

    Goal-directed therapy confers a strong prognosis in patients undergoing major cardiac or noncardiac surgery. The present study investigated whether intraoperative goal-directed fluid restriction (GDFR) using stroke volume variation (SVV) and cardiac index could improve oxygenation and postoperative outcome in patients undergoing one-lung ventilation (OLV). A Total of 168 patients scheduled for elective thoracoscopic lobectomy under OLV were randomized into the GDFR protocol (group G) or conventional fluid therapy groups (group C). Patients in group C underwent conventional fluid therapy based on mean arterial pressure (MAP), central venous pressure (CVP), and urine volume, whereas those in group G received GDFR protocol associated with the SVV from 10-13% and the cardiac index was controlled at a minimum of 2.5 L/min/m2. The primary outcome variable was PaO2/FiO2. The secondary outcomes were other pulmonary variables and lung mechanics, inflammatory response, the incidence of postoperative pulmonary complications, and the length of hospital stay. During surgery, the PaO2/FiO2 ratio in group G was more than that of group C at 30 and 60 min after OLV, 10 min after re-expansion, and the end of the operation (259±29 vs. 314±34; 253±30 vs. 308±35; 341±34 vs. 394±39; 349±35 vs. 401±39, respectively, all Pmechanics with the initiation of OLV. The incidence of postoperative pulmonary complications such as acute lung injury and pneumonia, and the length of hospital stay were decreased by GDFR protocol as compared to conventional fluid therapy (all P<0.05). However, there were no significant differences between groups with respect to the concentration of serum tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-10 (IL-10). The GDFR protocol based on SVV and cardiac index applied in patients undergoing OLV improves intraoperative pulmonary oxygenation. It can also reduce the postoperative complications and length of hospital stay. However, the

  2. Random Sampling of Squamate Reptiles in Spanish Natural Reserves Reveals the Presence of Novel Adenoviruses in Lacertids (Family Lacertidae) and Worm Lizards (Amphisbaenia).

    Science.gov (United States)

    Szirovicza, Leonóra; López, Pilar; Kopena, Renáta; Benkő, Mária; Martín, José; Pénzes, Judit J

    2016-01-01

    Here, we report the results of a large-scale PCR survey on the prevalence and diversity of adenoviruses (AdVs) in samples collected randomly from free-living reptiles. On the territories of the Guadarrama Mountains National Park in Central Spain and of the Chafarinas Islands in North Africa, cloacal swabs were taken from 318 specimens of eight native species representing five squamate reptilian families. The healthy-looking animals had been captured temporarily for physiological and ethological examinations, after which they were released. We found 22 AdV-positive samples in representatives of three species, all from Central Spain. Sequence analysis of the PCR products revealed the existence of three hitherto unknown AdVs in 11 Carpetane rock lizards (Iberolacerta cyreni), nine Iberian worm lizards (Blanus cinereus), and two Iberian green lizards (Lacerta schreiberi), respectively. Phylogeny inference showed every novel putative virus to be a member of the genus Atadenovirus. This is the very first description of the occurrence of AdVs in amphisbaenian and lacertid hosts. Unlike all squamate atadenoviruses examined previously, two of the novel putative AdVs had A+T rich DNA, a feature generally deemed to mirror previous host switch events. Our results shed new light on the diversity and evolution of atadenoviruses.

  3. Impact of an educational intervention on women's knowledge and acceptability of human papillomavirus self-sampling: a randomized controlled trial in Cameroon.

    Science.gov (United States)

    Sossauer, Gaëtan; Zbinden, Michel; Tebeu, Pierre-Marie; Fosso, Gisèle K; Untiet, Sarah; Vassilakos, Pierre; Petignat, Patrick

    2014-01-01

    Human papillomavirus (HPV) self-sampling (Self-HPV) may be used as a primary cervical cancer screening method in a low resource setting. Our aim was to evaluate whether an educational intervention would improve women's knowledge and confidence in the Self-HPV method. Women aged between 25 and 65 years old, eligible for cervical cancer screening, were randomly chosen to receive standard information (control group) or standard information followed by educational intervention (interventional group). Standard information included explanations about what the test detects (HPV), the link between HPV and cervical cancer and how to perform HPV self-sampling. The educational intervention consisted of a culturally tailored video about HPV, cervical cancer, Self-HPV and its relevancy as a screening test. All participants completed a questionnaire that assessed sociodemographic data, women's knowledge about cervical cancer and acceptability of Self-HPV. A total of 302 women were enrolled in 4 health care centers in Yaoundé and the surrounding countryside. 301 women (149 in the "control group" and 152 in the "intervention group") completed the full process and were included into the analysis. Participants who received the educational intervention had a significantly higher knowledge about HPV and cervical cancer than the control group (pEducational intervention promotes an increase in knowledge about HPV and cervical cancer. Further investigation should be conducted to determine if this intervention can be sustained beyond the short term and influences screening behavior. International Standard Randomised Controlled Trial Number (ISRCTN) Register ISRCTN78123709.

  4. What's in a name? The challenge of describing interventions in systematic reviews: analysis of a random sample of reviews of non-pharmacological stroke interventions.

    Science.gov (United States)

    Hoffmann, Tammy C; Walker, Marion F; Langhorne, Peter; Eames, Sally; Thomas, Emma; Glasziou, Paul

    2015-11-17

    To assess, in a sample of systematic reviews of non-pharmacological interventions, the completeness of intervention reporting, identify the most frequently missing elements, and assess review authors' use of and beliefs about providing intervention information. Analysis of a random sample of systematic reviews of non-pharmacological stroke interventions; online survey of review authors. The Cochrane Library and PubMed were searched for potentially eligible systematic reviews and a random sample of these assessed for eligibility until 60 (30 Cochrane, 30 non-Cochrane) eligible reviews were identified. In each review, the completeness of the intervention description in each eligible trial (n=568) was assessed by 2 independent raters using the Template for Intervention Description and Replication (TIDieR) checklist. All review authors (n=46) were invited to complete a survey. Most reviews were missing intervention information for the majority of items. The most incompletely described items were: modifications, fidelity, materials, procedure and tailoring (missing from all interventions in 97%, 90%, 88%, 83% and 83% of reviews, respectively). Items that scored better, but were still incomplete for the majority of reviews, were: 'when and how much' (in 31% of reviews, adequate for all trials; in 57% of reviews, adequate for some trials); intervention mode (in 22% of reviews, adequate for all trials; in 38%, adequate for some trials); and location (in 19% of reviews, adequate for all trials). Of the 33 (71%) authors who responded, 58% reported having further intervention information but not including it, and 70% tried to obtain information. Most focus on intervention reporting has been directed at trials. Poor intervention reporting in stroke systematic reviews is prevalent, compounded by poor trial reporting. Without adequate intervention descriptions, the conduct, usability and interpretation of reviews are restricted and therefore, require action by trialists

  5. Population structure of the pearly razorfish, Xyrichtys novacula (Actinopterygii: Labridae, in sand-seagrass mosaics: spatial variation according to habitat features and sampling techniques

    Directory of Open Access Journals (Sweden)

    Fernando Espino

    2015-06-01

    Full Text Available Habitat structure affects the distribution of fishes, particularly across reef-dominated habitats, but few studies have connected patterns in the abundance of soft-bottom fishes with the structure of the habitat. The spatial and temporal patterns of variation in the abundance, biomass and population structure of the pearly razorfish, Xyrichtys novacula, inhabiting sand-Cymodocea nodosa seagrass mosaics were described through two complementary techniques: underwater visual counts and seine nets. We sought to analyse whether biotic (seagrass shoot density, leaf length and meadow cover and abiotic (sediment composition and particle size structural elements explained variation in patterns of abundance and biomass. Underwater visual counts registered a larger abundance of individuals and proved significant variation in fish abundance and biomass at the scale of locations, which was otherwise not detected through seine nets. Seasonal variation in fish abundance and biomass was, in all cases, minor. Habitat structural elements helped to explain patterns in fish abundance and biomass. This fish species was particularly abundant in sediments dominated by coarse sands in continuous meadows of C. nodosa ( > 90% seagrass cover with intermediate densities of 500 to 1000 shoots m–2, followed by large-sized seagrass patches with >1000 shoots m–2. A trade-off between protection provided by seagrass canopies and protection derived from its burial behaviour, limited under high seagrass shoot densities, may explain spatial variation patterns.

  6. Analytical decision model for sample size and effectiveness projections for use in planning a population-based randomized controlled trial of colorectal cancer screening.

    Science.gov (United States)

    Chiu, Sherry Y-H; Malila, Nea; Yen, Amy M-F; Anttila, Ahti; Hakama, Matti; Chen, H-H

    2011-02-01

    Population-based randomized controlled trials (RCTs) often involve enormous costs and long-term follow-up to evaluate primary end points. Analytical decision-simulated model for sample size and effectiveness projections based on primary and surrogate end points are necessary before planning a population-based RCT. Based on the study design similar to two previous RCTs, transition rates were estimated using a five-state natural history model [normal, preclinical detection phase (PCDP) Dukes' A/B, PCDP Dukes' C/D, Clinical Dukes' A/B and Clinical Dukes' C/D]. The Markov cycle tree was assigned transition parameters, variables related to screening and survival rate that simulated results of 10-year follow-up in the absence of screening for a hypothetical cohort aged 45-74 years. The corresponding screened arm was to simulate the results after the introduction of population-based screening for colorectal cancer with fecal occult blood test with stop screen design. The natural course of mean sojourn time for five-state Markov model were estimated as 2.75 years for preclinical Dukes' A/B and 1.38 years for preclinical Dukes' C/D. The expected reductions in mortality and Dukes' C/D were 13% (95% confidence intervals: 7-19%) and 26% (95% confidence intervals: 20-32%), respectively, given a 70% acceptance rate and a 90% colonoscopy referral rate. Sample sizes required were 86,150 and 65,592 subjects for the primary end point and the surrogate end point, respectively, given an incidence rate up to 0.0020 per year. The sample sizes required for primary and surrogate end points and the projection of effectiveness of fecal occult blood test for colorectal cancer screening were developed. Both are very important to plan a population-based RCT. © 2010 Blackwell Publishing Ltd.

  7. Characterizing stand-level forest canopy cover and height using Landsat time series, samples of airborne LiDAR, and the Random Forest algorithm

    Science.gov (United States)

    Ahmed, Oumer S.; Franklin, Steven E.; Wulder, Michael A.; White, Joanne C.

    2015-03-01

    Many forest management activities, including the development of forest inventories, require spatially detailed forest canopy cover and height data. Among the various remote sensing technologies, LiDAR (Light Detection and Ranging) offers the most accurate and consistent means for obtaining reliable canopy structure measurements. A potential solution to reduce the cost of LiDAR data, is to integrate transects (samples) of LiDAR data with frequently acquired and spatially comprehensive optical remotely sensed data. Although multiple regression is commonly used for such modeling, often it does not fully capture the complex relationships between forest structure variables. This study investigates the potential of Random Forest (RF), a machine learning technique, to estimate LiDAR measured canopy structure using a time series of Landsat imagery. The study is implemented over a 2600 ha area of industrially managed coastal temperate forests on Vancouver Island, British Columbia, Canada. We implemented a trajectory-based approach to time series analysis that generates time since disturbance (TSD) and disturbance intensity information for each pixel and we used this information to stratify the forest land base into two strata: mature forests and young forests. Canopy cover and height for three forest classes (i.e. mature, young and mature and young (combined)) were modeled separately using multiple regression and Random Forest (RF) techniques. For all forest classes, the RF models provided improved estimates relative to the multiple regression models. The lowest validation error was obtained for the mature forest strata in a RF model (R2 = 0.88, RMSE = 2.39 m and bias = -0.16 for canopy height; R2 = 0.72, RMSE = 0.068% and bias = -0.0049 for canopy cover). This study demonstrates the value of using disturbance and successional history to inform estimates of canopy structure and obtain improved estimates of forest canopy cover and height using the RF algorithm.

  8. Employing a Multi-level Approach to Recruit a Representative Sample of Women with Recent Gestational Diabetes Mellitus into a Randomized Lifestyle Intervention Trial.

    Science.gov (United States)

    Nicklas, Jacinda M; Skurnik, Geraldine; Zera, Chloe A; Reforma, Liberty G; Levkoff, Sue E; Seely, Ellen W

    2016-02-01

    The postpartum period is a window of opportunity for diabetes prevention in women with recent gestational diabetes (GDM), but recruitment for clinical trials during this period of life is a major challenge. We adapted a social-ecologic model to develop a multi-level recruitment strategy at the macro (high or institutional level), meso (mid or provider level), and micro (individual) levels. Our goal was to recruit 100 women with recent GDM into the Balance after Baby randomized controlled trial over a 17-month period. Participants were asked to attend three in-person study visits at 6 weeks, 6, and 12 months postpartum. They were randomized into a control arm or a web-based intervention arm at the end of the baseline visit at six weeks postpartum. At the end of the recruitment period, we compared population characteristics of our enrolled subjects to the entire population of women with GDM delivering at Brigham and Women's Hospital (BWH). We successfully recruited 107 of 156 (69 %) women assessed for eligibility, with the majority (92) recruited during pregnancy at a mean 30 (SD ± 5) weeks of gestation, and 15 recruited postpartum, at a mean 2 (SD ± 3) weeks postpartum. 78 subjects attended the initial baseline visit, and 75 subjects were randomized into the trial at a mean 7 (SD ± 2) weeks postpartum. The recruited subjects were similar in age and race/ethnicity to the total population of 538 GDM deliveries at BWH over the 17-month recruitment period. Our multilevel approach allowed us to successfully meet our recruitment goal and recruit a representative sample of women with recent GDM. We believe that our most successful strategies included using a dedicated in-person recruiter, integrating recruitment into clinical flow, allowing for flexibility in recruitment, minimizing barriers to participation, and using an opt-out strategy with providers. Although the majority of women were recruited while pregnant, women recruited in the early postpartum period were

  9. A description of the demographic characteristics of the New Zealand non-commercial horse population with data collected using a generalised random-tessellation stratified sampling design.

    Science.gov (United States)

    Rosanowski, S M; Cogger, N; Rogers, C W; Benschop, J; Stevenson, M A

    2012-12-01

    We conducted a cross-sectional survey to determine the demographic characteristics of non-commercial horses in New Zealand. A sampling frame of properties with non-commercial horses was derived from the national farms database, AgriBase™. Horse properties were stratified by property size and a generalised random-tessellated stratified (GRTS) sampling strategy was used to select properties (n=2912) to take part in the survey. The GRTS sampling design allowed for the selection of properties that were spatially balanced relative to the distribution of horse properties throughout the country. The registered decision maker of the property, as identified in AgriBase™, was sent a questionnaire asking them to describe the demographic characteristics of horses on the property, including the number and reason for keeping horses, as well as information about other animals kept on the property and the proximity of boundary neighbours with horses. The response rate to the survey was 38% (1044/2912) and the response rate was not associated with property size or region. A total of 5322 horses were kept for recreation, competition, racing, breeding, stock work, or as pets. The reasons for keeping horses and the number and class of horses varied significantly between regions and by property size. Of the properties sampled, less than half kept horses that could have been registered with Equestrian Sports New Zealand or either of the racing codes. Of the respondents that reported knowing whether their neighbours had horses, 58.6% (455/776) of properties had at least one boundary neighbour that kept horses. The results of this study have important implications for New Zealand, which has an equine population that is naïve to many equine diseases considered endemic worldwide. The ability to identify, and apply accurate knowledge of the population at risk to infectious disease control strategies would lead to more effective strategies to control and prevent disease spread during an

  10. Application of bimodal distribution to the detection of changes in uranium concentration in drinking water collected by random daytime sampling method from a large water supply zone.

    Science.gov (United States)

    Garboś, Sławomir; Święcicka, Dorota

    2015-11-01

    The random daytime (RDT) sampling method was used for the first time in the assessment of average weekly exposure to uranium through drinking water in a large water supply zone. Data set of uranium concentrations determined in 106 RDT samples collected in three runs from the water supply zone in Wroclaw (Poland), cannot be simply described by normal or log-normal distributions. Therefore, a numerical method designed for the detection and calculation of bimodal distribution was applied. The extracted two distributions containing data from the summer season of 2011 and the winter season of 2012 (nI=72) and from the summer season of 2013 (nII=34) allowed to estimate means of U concentrations in drinking water: 0.947 μg/L and 1.23 μg/L, respectively. As the removal efficiency of uranium during applied treatment process is negligible, the effect of increase in uranium concentration can be explained by higher U concentration in the surface-infiltration water used for the production of drinking water. During the summer season of 2013, heavy rains were observed in Lower Silesia region, causing floods over the territory of the entire region. Fluctuations in uranium concentrations in surface-infiltration water can be attributed to releases of uranium from specific sources - migration from phosphate fertilizers and leaching from mineral deposits. Thus, exposure to uranium through drinking water may increase during extreme rainfall events. The average chronic weekly intakes of uranium through drinking water, estimated on the basis of central values of the extracted normal distributions, accounted for 3.2% and 4.1% of tolerable weekly intake. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Association between Spouse/Child Separation and Migration-Related Stress among a Random Sample of Rural-to-Urban Migrants in Wuhan, China.

    Science.gov (United States)

    Guo, Yan; Chen, Xinguang; Gong, Jie; Li, Fang; Zhu, Chaoyang; Yan, Yaqiong; Wang, Liang

    2016-01-01

    Millions of people move from rural areas to urban areas in China to pursue new opportunities while leaving their spouses and children at rural homes. Little is known about the impact of migration-related separation on mental health of these rural migrants in urban China. Survey data from a random sample of rural-to-urban migrants (n = 1113, aged 18-45) from Wuhan were analyzed. The Domestic Migration Stress Questionnaire (DMSQ), an instrument with four subconstructs, was used to measure migration-related stress. The relationship between spouse/child separation and stress was assessed using survey estimation methods to account for the multi-level sampling design. 16.46% of couples were separated from their spouses (spouse-separation only), 25.81% of parents were separated from their children (child separation only). Among the participants who married and had children, 5.97% were separated from both their spouses and children (double separation). Spouse-separation only and double separation did not scored significantly higher on DMSQ than those with no separation. Compared to parents without child separation, parents with child separation scored significantly higher on DMSQ (mean score = 2.88, 95% CI: [2.81, 2.95] vs. 2.60 [2.53, 2.67], p child-separation only and for female participants. Child-separation is an important source of migration-related stress, and the effect is particularly strong for migrant women. Public policies and intervention programs should consider these factors to encourage and facilitate the co-migration of parents with their children to mitigate migration-related stress.

  12. Influence of cigarette smoking on coronary artery and aortic calcium among random samples from populations of middle-age Japanese and Korean men

    Science.gov (United States)

    Hirooka, Nobutaka; Kadowaki, Takashi; Sekikawa, Akira; Ueshima, Hirotsugu; Choo, Jina; Miura, Katsuyuki; Okamura, Tomonori; Fujiyoshi, Akira; Kadowaki, Sayaka; Kadota, Aya; Nakamura, Yasuyuki; Maegawa, Hiroshi; Kashiwagi, Atsunori; Masaki, Kamal; Sutton-Tyrrell, Kim; Kuller, Lewis H.; Curb, J. David; Shin, Chol

    2012-01-01

    Background Cigarette smoking is a risk factor of coronary heart disease (CHD). Vascular calcification such as coronary artery calcium (CAC) and aortic calcium (AC) is associated with CHD. We hypothesized that cigarette smoking is associated with coronary artery and aortic calcifications in Japanese and Koreans with high smoking prevalence. Methods Random samples from populations of 313 Japanese and 302 Korean men aged 40 to 49 were examined for calcification of the coronary artery and aorta using electron beam computed tomography. Coronary artery calcium (CAC) and aortic calcium (AC) were quantified using the Agatston score. We examined the associations of cigarette smoking with CAC and AC after adjusting for conventional risk factors and alcohol consumption. Current and past smokers were combined and categorized into two groups using median pack-years as a cutoff point in each of Japanese and Koreans. The never smoker group was used as a reference for the multiple logistic regression analyses. Results The odds ratios of CAC (score ≥10) for smokers with higher pack-years were 2.9 in Japanese (PKoreans (non-significant) compared to never smokers. The odds ratios of AC (score ≥100) for smokers with higher pack-years were 10.4 in Japanese (PKoreans (Psmoking with higher pack-years is significantly associated with CAC and AC in Japanese men, while cigarette smoking with higher pack-years is significantly associated with AC but not significantly with CAC in Korean men. PMID:22844083

  13. Influence of cigarette smoking on coronary artery and aortic calcium among random samples from populations of middle-aged Japanese and Korean men.

    Science.gov (United States)

    Hirooka, Nobutaka; Kadowaki, Takashi; Sekikawa, Akira; Ueshima, Hirotsugu; Choo, Jina; Miura, Katsuyuki; Okamura, Tomonori; Fujiyoshi, Akira; Kadowaki, Sayaka; Kadota, Aya; Nakamura, Yasuyuki; Maegawa, Hiroshi; Kashiwagi, Atsunori; Masaki, Kamal; Sutton-Tyrrell, Kim; Kuller, Lewis H; Curb, J David; Shin, Chol

    2013-02-01

    Cigarette smoking is a risk factor of coronary heart disease. Vascular calcification such as coronary artery calcium (CAC) and aortic calcium (AC) is associated with coronary heart disease. The authors hypothesised that cigarette smoking is associated with coronary artery and aortic calcifications in Japanese and Koreans with high smoking prevalence. Random samples from populations of 313 Japanese and 302 Korean men aged 40-49 years were examined for calcification of the coronary artery and aorta using electron beam CT. CAC and AC were quantified using the Agatston score. The authors examined the associations of cigarette smoking with CAC and AC after adjusting for conventional risk factors and alcohol consumption. Current and past smokers were combined and categorised into two groups using median pack-years as a cut-off point in each of Japanese and Koreans. The never-smoker group was used as a reference for the multiple logistic regression analyses. The ORs of CAC (score ≥10) for smokers with higher pack-years were 2.9 in Japanese (pKoreans (non-significant) compared with never-smokers. The ORs of AC (score ≥100) for smokers with higher pack-years were 10.4 in Japanese (pKoreans (psmoking with higher pack-years is significantly associated with CAC and AC in Japanese men, while cigarette smoking with higher pack-years is significantly associated with AC but not significantly with CAC in Korean men.

  14. A profile of US-Mexico border mobility among a stratified random sample of Hispanics living in the El Paso-Juarez area.

    Science.gov (United States)

    Lapeyrouse, L M; Morera, O; Heyman, J M C; Amaya, M A; Pingitore, N E; Balcazar, H

    2012-04-01

    Examination of border-specific characteristics such as trans-border mobility and transborder health service illuminates the heterogeneity of border Hispanics and may provide greater insight toward understanding differential health behaviors and status among these populations. In this study, we create a descriptive profile of the concept of trans-border mobility by exploring the relationship between mobility status and a series of demographic, economic and socio-cultural characteristics among mobile and non-mobile Hispanics living in the El Paso-Juarez border region. Using a two-stage stratified random sampling design, bilingual interviewers collected survey data from border residents (n = 1,002). Findings show that significant economic, cultural, and behavioral differences exist between mobile and non-mobile respondents. While non-mobile respondents were found to have higher social economic status than their mobile counterparts, mobility across the border was found to offer less acculturated and poorer Hispanics access to alternative sources of health care and other services.

  15. Physical abuse of older adults in nursing homes: a random sample survey of adults with an elderly family member in a nursing home.

    Science.gov (United States)

    Schiamberg, Lawrence B; Oehmke, James; Zhang, Zhenmei; Barboza, Gia E; Griffore, Robert J; Von Heydrich, Levente; Post, Lori A; Weatherill, Robin P; Mastin, Teresa

    2012-01-01

    Few empirical studies have focused on elder abuse in nursing home settings. The present study investigated the prevalence and risk factors of staff physical abuse among elderly individuals receiving nursing home care in Michigan. A random sample of 452 adults with elderly relatives, older than 65 years, and in nursing home care completed a telephone survey regarding elder abuse and neglect experienced by this elder family member in the care setting. Some 24.3% of respondents reported at least one incident of physical abuse by nursing home staff. A logistic regression model was used to estimate the importance of various risk factors in nursing home abuse. Limitations in activities of daily living (ADLs), older adult behavioral difficulties, and previous victimization by nonstaff perpetrators were associated with a greater likelihood of physical abuse. Interventions that address these risk factors may be effective in reducing older adult physical abuse in nursing homes. Attention to the contextual or ecological character of nursing home abuse is essential, particularly in light of the findings of this study.

  16. Thermal discomfort with cold extremities in relation to age, gender, and body mass index in a random sample of a Swiss urban population

    Directory of Open Access Journals (Sweden)

    Orgül Selim

    2010-06-01

    Full Text Available Abstract Background The aim of this epidemiological study was to investigate the relationship of thermal discomfort with cold extremities (TDCE to age, gender, and body mass index (BMI in a Swiss urban population. Methods In a random population sample of Basel city, 2,800 subjects aged 20-40 years were asked to complete a questionnaire evaluating the extent of cold extremities. Values of cold extremities were based on questionnaire-derived scores. The correlation of age, gender, and BMI to TDCE was analyzed using multiple regression analysis. Results A total of 1,001 women (72.3% response rate and 809 men (60% response rate returned a completed questionnaire. Statistical analyses revealed the following findings: Younger subjects suffered more intensely from cold extremities than the elderly, and women suffered more than men (particularly younger women. Slimmer subjects suffered significantly more often from cold extremities than subjects with higher BMIs. Conclusions Thermal discomfort with cold extremities (a relevant symptom of primary vascular dysregulation occurs at highest intensity in younger, slimmer women and at lowest intensity in elderly, stouter men.

  17. Balancing selection, random genetic drift, and genetic variation at the major histocompatibility complex in two wild populations of guppies (Poecilia reticulata).

    Science.gov (United States)

    Van Oosterhout, Cock; Joyce, Domino A; Cummings, Stephen M; Blais, Jonatan; Barson, Nicola J; Ramnarine, Indar W; Mohammed, Ryan S; Persad, Nadia; Cable, Joanne

    2006-12-01

    Our understanding of the evolution of genes of the major histocompatibility complex (MHC) is rapidly increasing, but there are still enigmatic questions remaining, particularly regarding the maintenance of high levels of MHC polymorphisms in small, isolated populations. Here, we analyze the genetic variation at eight microsatellite loci and sequence variation at exon 2 of the MHC class IIB (DAB) genes in two wild populations of the Trinidadian guppy, Poecilia reticulata. We compare the genetic variation of a small (Ne, 100) and relatively isolated upland population to that of its much larger (Ne approximately 2400) downstream counterpart. As predicted, microsatellite diversity in the upland population is significantly lower and highly differentiated from the population further downstream. Surprisingly, however, these guppy populations are not differentiated by MHC genetic variation and show very similar levels of allelic richness. Computer simulations indicate that the observed level of genetic variation can be maintained with overdominant selection acting at three DAB loci. The selection coefficients differ dramatically between the upland (s > or = 0.2) and lowland (s guppies in the upland habitat, which has resulted in high levels of MHC diversity being maintained in this population despite considerable genetic drift.

  18. The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormones Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

    Science.gov (United States)

    2014-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. The Bottlenose Dolphin ( Tursiops truncatus ) as a Model to...2014 4. TITLE AND SUBTITLE The Bottlenose Dolphin ( Tursiops truncatus ) as a Model to Understand Variation in Stress and Reproductive Hormones...Schwacke LH, Smith CR, Townsend FI, Wells RS, Hart LB, et al. (2014) Health of Common Bottlenose Dolphins ( Tursiops truncatus ) in Barataria Bay

  19. Predictors of poor retention on antiretroviral therapy as a major HIV drug resistance early warning indicator in Cameroon: results from a nationwide systematic random sampling

    Directory of Open Access Journals (Sweden)

    Serge Clotaire Billong

    2016-11-01

    Full Text Available Abstract Background Retention on lifelong antiretroviral therapy (ART is essential in sustaining treatment success while preventing HIV drug resistance (HIVDR, especially in resource-limited settings (RLS. In an era of rising numbers of patients on ART, mastering patients in care is becoming more strategic for programmatic interventions. Due to lapses and uncertainty with the current WHO sampling approach in Cameroon, we thus aimed to ascertain the national performance of, and determinants in, retention on ART at 12 months. Methods Using a systematic random sampling, a survey was conducted in the ten regions (56 sites of Cameroon, within the “reporting period” of October 2013–November 2014, enrolling 5005 eligible adults and children. Performance in retention on ART at 12 months was interpreted following the definition of HIVDR early warning indicator: excellent (>85%, fair (85–75%, poor (<75; and factors with p-value < 0.01 were considered statistically significant. Results Majority (74.4% of patients were in urban settings, and 50.9% were managed in reference treatment centres. Nationwide, retention on ART at 12 months was 60.4% (2023/3349; only six sites and one region achieved acceptable performances. Retention performance varied in reference treatment centres (54.2% vs. management units (66.8%, p < 0.0001; male (57.1% vs. women (62.0%, p = 0.007; and with WHO clinical stage I (63.3% vs. other stages (55.6%, p = 0.007; but neither for age (adults [60.3%] vs. children [58.8%], p = 0.730 nor for immune status (CD4351–500 [65.9%] vs. other CD4-staging [59.86%], p = 0.077. Conclusions Poor retention in care, within 12 months of ART initiation, urges active search for lost-to-follow-up targeting preferentially male and symptomatic patients, especially within reference ART clinics. Such sampling strategy could be further strengthened for informed ART monitoring and HIVDR prevention perspectives.

  20. Modern survey sampling

    CERN Document Server

    Chaudhuri, Arijit

    2014-01-01

    Exposure to SamplingAbstract Introduction Concepts of Population, Sample, and SamplingInitial RamificationsAbstract Introduction Sampling Design, Sampling SchemeRandom Numbers and Their Uses in Simple RandomSampling (SRS)Drawing Simple Random Samples with and withoutReplacementEstimation of Mean, Total, Ratio of Totals/Means:Variance and Variance EstimationDetermination of Sample SizesA.2 Appendix to Chapter 2 A.More on Equal Probability Sampling A.Horvitz-Thompson EstimatorA.SufficiencyA.LikelihoodA.Non-Existence Theorem More Intricacies Abstract Introduction Unequal Probability Sampling StrategiesPPS Sampling Exploring Improved WaysAbstract Introduction Stratified Sampling Cluster SamplingMulti-Stage SamplingMulti-Phase Sampling: Ratio and RegressionEstimationviiviii ContentsControlled SamplingModeling Introduction Super-Population ModelingPrediction Approach Model-Assisted Approach Bayesian Methods Spatial SmoothingSampling on Successive Occasions: Panel Rotation Non-Response and Not-at-Homes Weighting Adj...

  1. Motivational Determinants of Status Aspirations: Comments on Sex Variations.

    Science.gov (United States)

    Picou, J. Steven; Howard, William G.

    The impact of sex-role socialization on career-related status orientations was examined in an attempt to specify, by sex, differential reference group influence and motivational variations. Data were derived from a larger data-set on mobility and achievement orientations of a random sample of 1970 senior students stratified according to residence…

  2. Genetic variation studies in Oryctes rhinoceros (L.) (Coleoptera ...

    African Journals Online (AJOL)

    Randomly amplified microsatellite markers were used to study the genetic variation among six populations of Oryctes rhinoceros L. which were collected from oil palm plantations in Selangor, Perak, Pahang and Medan. Samples were collected using light and pheromone trapping for the purpose of obtaining two ...

  3. Analyses of spatial variations of kenaf in experimental field | Dauda ...

    African Journals Online (AJOL)

    Preliminary investigations of experimental field usually involve collection of soil samples at widely spaced locations which are patchily or globally at variant spatially. This study was carried out to evaluate spatial variations in experimental fields using a split plot experiment distributed in a completely randomized design at ...

  4. Unit-specific calibration of Actigraph accelerometers in a mechanical setup - is it worth the effort? The effect on random output variation caused by technical inter-instrument variability in the laboratory and in the field

    DEFF Research Database (Denmark)

    Moeller, Niels C; Korsholm, Lars; Kristensen, Peter L

    2008-01-01

    BACKGROUND: Potentially, unit-specific in-vitro calibration of accelerometers could increase field data quality and study power. However, reduced inter-unit variability would only be important if random instrument variability contributes considerably to the total variation in field data. Therefore...... during free living conditions. RESULTS: Calibration reduced inter-instrument variability considerably in the mechanical setup, both in the MTI instruments (raw SDbetween units = 195 counts*min-1 vs. calibrated SDbetween units = 65 counts*min-1) and in the CSA instruments (raw SDbetween units = 343 counts......*min-1 vs. calibrated SDbetween units = 67 counts*min-1). However, the effect of applying the derived calibration to children's and adolescents' free living physical activity data did not alter the coefficient of variation (CV) (children: CVraw = 30.2% vs. CVcalibrated = 30.4%, adolescents: CVraw = 36...

  5. An Abecedary of Sampling.

    Science.gov (United States)

    Doyle, Kenneth O., Jr.

    1979-01-01

    The vocabulary of sampling is examined in order to provide a clear understanding of basic sampling concepts. The basic vocabulary of sampling (population, probability sampling, precision and bias, stratification), the fundamental grammar of sampling (random sample), sample size and response rate, and cluster, multiphase, snowball, and panel…

  6. INFLUENCE OF VARIATIONS OF THE CONDUCTIVITY OF UPPER LAYER OF TWO-LAYER SAMPLE ON OF PHASE INTRODUCED ELECTROMOTIVE FORCE OF SUPERIMPOSED TRANSDUCER OF EDDY CURRENT THICKNESS METER

    Directory of Open Access Journals (Sweden)

    A. V. Chernyshev

    2017-01-01

    Full Text Available In carrying out eddy current thickness measurement of two-layer conductive objects one from the interfering factors is the presence of variations in the value of the electrical conductivity of the material of the upper layer (coating when moving from point to point on the surface of object of control or when passing from one object of control to another. The aim of this work is to evaluate the accuracy of determining the thickness of the conductive coating disposed on a conducting ferromagnetic basis, using the phase method of eddy current testing. The reason of the error is variation of the electrical conductivity of the material of coating.Determination of the error is based on calculations using known analytical expressions for the loop with current of sinusoidal form arranged over the infinite half space with a covering as a thin layer. Selected in calculating electromagnetic parameters of coating and substrate approximately correspond to the case -chromium layer on a nickel base. Calculations are performed for different frequencies of current passed through coil.It is shown that at reduction of frequency of the current passes through the coil the error is reduced. The value of the lowest possible operating frequency of the excitation current is determined by the condition of absence influence on the phase introduced into the superimposed transducer emf variations in the thickness of the basis.To reduce the indicated error it is proposed to determine, on the basis of phase method at a relatively high frequency transducer current excitation, conductivity of the material of coating. After this, at a low frequency excitation current and using phase method, the coating thickness is determined, taking into consideration the previously determined value of the conductivity of coating. Also discussed ways to improve the accuracy of phase measurements in the MHz region of the excitation current frequency. 

  7. [Analysis on intraspecific variation of Cnidium monnieri by RAPD].

    Science.gov (United States)

    Zhang, Qiaoyan; Qin, Luping; Zheng, Hanchen; Huang, Baokang; Nian, Hua; Chen, Lei

    2004-07-01

    To study the genetic variation of Cnidium monnieri from different regions. Random amplified polymophic DNA technique was used to analyze genetic polymorphy of Cnidium monnieri from 9 different regions, and dendrogram was constructed by UPGMA. 20 random primers were used for polymorphic selection. A total of 75 bands were amplified, 64 of which were polymorphism. The smaller the geographic distances between two Cnidium monnieri, the smaller genetic differences. However, it should not be overlooked that natural environment, especially the local ecological conditions may also show some influences on the genetic variations among different C. monnieri samples.

  8. Biological investigations of Indian phaeophyceae: 17. Seasonal variation of antibacterial activity of total sterols obtained from frozen samples of Sargassum johnstonii Setchell et Gardner

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, P.P.S.

    From lipid fraction of frozen samples of Sargassum johnstonii unsaponifiable part was extracted with diethyl ether to isolate total sterols. The extracted sterols were obtained for a period of nine months and tested against test bacteria...

  9. Self-help interventions for adjustment disorder problems: a randomized waiting-list controlled study in a sample of burglary victims.

    Science.gov (United States)

    Bachem, Rahel; Maercker, Andreas

    2016-09-01

    Adjustment disorders (AjD) are among the most frequent mental disorders yet often remain untreated. The high prevalence, comparatively mild symptom impairment, and transient nature make AjD a promising target for low-threshold self-help interventions. Bibliotherapy represents a potential treatment for AjD problems. This study investigates the effectiveness of a cognitive behavioral self-help manual specifically directed at alleviating AjD symptoms in a homogenous sample of burglary victims. Participants with clinical or subclinical AjD symptoms following experience of burglary were randomized to an intervention group (n = 30) or waiting-list control group (n = 24). The new explicit stress response syndrome model for diagnosing AjD was applied. Participants received no therapist support and assessments took place at baseline, after the one-month intervention, and at three-month follow-up. Based on completer analyses, group by time interactions indicated that the intervention group showed more improvement in AjD symptoms of preoccupation and in post-traumatic stress symptoms. Post-intervention between-group effect sizes ranged from Cohen's d = .17 to .67 and the proportion of participants showing reliable change was consistently higher in the intervention group than in the control group. Engagement with the self-help manual was high: 87% of participants had worked through at least half the manual. This is the first published RCT of a bibliotherapeutic self-help intervention for AjD problems. The findings provide evidence that a low-threshold self-help intervention without therapist contact is a feasible and effective treatment for symptoms of AjD.

  10. 22G versus 25G biopsy needles for EUS-guided tissue sampling of solid pancreatic masses: a randomized controlled study.

    Science.gov (United States)

    Woo, Young Sik; Lee, Kwang Hyuck; Noh, Dong Hyo; Park, Joo Kyung; Lee, Kyu Taek; Lee, Jong Kyun; Jang, Kee-Taek

    2017-12-01

    No comparative study of 22-gauge biopsy needles (PC22) and 25-gauge biopsy needles (PC25) has been conducted. We prospectively compared the diagnostic accuracy of PC22 and PC25 in patients with pancreatic and peripancreatic solid masses. We conducted a randomized noninferiority clinical study from January 2013 to May 2014 at Samsung Medical Center. A cytological and histological specimen of each pass was analyzed separately by an experienced pathologist. The primary outcome was to assess the diagnostic accuracy using the PC22 or PC25. Secondary outcomes included the optimal number of passes for adequate diagnosis, core specimen yield, sample adequacy, and complication rates. Diagnostic accuracy of combining cytology with histology in three cumulative passes was 97.1% (100/103) for the PC22 and 91.3% (94/103) for the PC25 group. Thus, noninferiority of PC25 to PC22 was not shown with a 10% noninferiority margin (difference, -5.8%; 95% CI, -12.1 to -0.5%). In a pairwise comparison with each needle type, two passes was non-inferior to three passes in the PC22 (96.1% vs. 97.1%; difference, -0.97%; 95% CI -6.63 to 4.69%) but noninferiority of two passes to three passes was not shown in the PC25 group (87.4% vs. 91.3%; difference, -3.88%; 95% CI, -13.5 to 5.7%). Non-inferiority of PC25 to PC22 diagnostic accuracy was not observed for solid pancreatic or peripancreatic masses without on-site cytology. PC22 may be a more ideal device because only two PC22 needle passes was sufficient to establish an adequate diagnosis, whereas PC25 required three or more needle passes.

  11. Chronic kidney disease in the type 2 diabetic patients: prevalence and associated variables in a random sample of 2642 patients of a Mediterranean area

    Directory of Open Access Journals (Sweden)

    Coll-de-Tuero Gabriel

    2012-08-01

    Full Text Available Abstract Background Kidney disease is associated with an increased total mortality and cardiovascular morbimortality in the general population and in patients with Type 2 diabetes. The aim of this study is to determine the prevalence of kidney disease and different types of renal disease in patients with type 2 diabetes (T2DM. Methods Cross-sectional study in a random sample of 2,642 T2DM patients cared for in primary care during 2007. Studied variables: demographic and clinical characteristics, pharmacological treatments and T2DM complications (diabetic foot, retinopathy, coronary heart disease and stroke. Variables of renal function were defined as follows: 1 Microalbuminuria: albumin excretion rate & 30 mg/g or 3.5 mg/mmol, 2 Macroalbuminuria: albumin excretion rate & 300 mg/g or 35 mg/mmol, 3 Kidney disease (KD: glomerular filtration rate according to Modification of Diet in Renal Disease 2 and/or the presence of albuminuria, 4 Renal impairment (RI: glomerular filtration rate 2, 5 Nonalbuminuric RI: glomerular filtration rate 2 without albuminuria and, 5 Diabetic nephropathy (DN: macroalbuminuria or microalbuminuria plus diabetic retinopathy. Results The prevalence of different types of renal disease in patients was: 34.1% KD, 22.9% RI, 19.5% albuminuria and 16.4% diabetic nephropathy (DN. The prevalence of albuminuria without RI (13.5% and nonalbuminuric RI (14.7% was similar. After adjusting per age, BMI, cholesterol, blood pressure and macrovascular disease, RI was significantly associated with the female gender (OR 2.20; CI 95% 1.86–2.59, microvascular disease (OR 2.14; CI 95% 1.8–2.54 and insulin treatment (OR 1.82; CI 95% 1.39–2.38, and inversely associated with HbA1c (OR 0.85 for every 1% increase; CI 95% 0.80–0.91. Albuminuria without RI was inversely associated with the female gender (OR 0.27; CI 95% 0.21–0.35, duration of diabetes (OR 0.94 per year; CI 95% 0.91–0.97 and directly associated with HbA1c (OR 1.19 for every

  12. Children's Quality of Life Based on the KIDSCREEN-27: Child Self-Report, Parent Ratings and Child-Parent Agreement in a Swedish Random Population Sample.

    Directory of Open Access Journals (Sweden)

    Anne H Berman

    Full Text Available The KIDSCREEN-27 is a measure of child and adolescent quality of life (QoL, with excellent psychometric properties, available in child-report and parent-rating versions in 38 languages. This study provides child-reported and parent-rated norms for the KIDSCREEN-27 among Swedish 11-16 year-olds, as well as child-parent agreement. Sociodemographic correlates of self-reported wellbeing and parent-rated wellbeing were also measured.A random population sample consisting of 600 children aged 11-16, 100 per age group and one of their parents (N = 1200, were approached for response to self-reported and parent-rated versions of the KIDSCREEN-27. Parents were also asked about their education, employment status and their own QoL based on the 26-item WHOQOL-Bref. Based on the final sampling pool of 1158 persons, a 34.8% response rate of 403 individuals was obtained, including 175 child-parent pairs, 27 child singleton responders and 26 parent singletons. Gender and age differences for parent ratings and child-reported data were analyzed using t-tests and the Mann-Whitney U-test. Post-hoc Dunn tests were conducted for pairwise comparisons when the p-value for specific subscales was 0.05 or lower. Child-parent agreement was tested item-by-item, using the Prevalence- and Bias-Adjusted Kappa (PABAK coefficient for ordinal data (PABAK-OS; dimensional and total score agreement was evaluated based on dichotomous cut-offs for lower well-being, using the PABAK and total, continuous scores were evaluated using Bland-Altman plots.Compared to European norms, Swedish children in this sample scored lower on Physical wellbeing (48.8 SE/49.94 EU but higher on the other KIDSCREEN-27 dimensions: Psychological wellbeing (53.4/49.77, Parent relations and autonomy (55.1/49.99, Social Support and peers (54.1/49.94 and School (55.8/50.01. Older children self-reported lower wellbeing than younger children. No significant self-reported gender differences occurred and parent ratings

  13. Children’s Quality of Life Based on the KIDSCREEN-27: Child Self-Report, Parent Ratings and Child-Parent Agreement in a Swedish Random Population Sample

    Science.gov (United States)

    Berman, Anne H.; Liu, Bojing; Ullman, Sara; Jadbäck, Isabel; Engström, Karin

    2016-01-01

    Background The KIDSCREEN-27 is a measure of child and adolescent quality of life (QoL), with excellent psychometric properties, available in child-report and parent-rating versions in 38 languages. This study provides child-reported and parent-rated norms for the KIDSCREEN-27 among Swedish 11–16 year-olds, as well as child-parent agreement. Sociodemographic correlates of self-reported wellbeing and parent-rated wellbeing were also measured. Methods A random population sample consisting of 600 children aged 11–16, 100 per age group and one of their parents (N = 1200), were approached for response to self-reported and parent-rated versions of the KIDSCREEN-27. Parents were also asked about their education, employment status and their own QoL based on the 26-item WHOQOL-Bref. Based on the final sampling pool of 1158 persons, a 34.8% response rate of 403 individuals was obtained, including 175 child-parent pairs, 27 child singleton responders and 26 parent singletons. Gender and age differences for parent ratings and child-reported data were analyzed using t-tests and the Mann-Whitney U-test. Post-hoc Dunn tests were conducted for pairwise comparisons when the p-value for specific subscales was 0.05 or lower. Child-parent agreement was tested item-by-item, using the Prevalence- and Bias-Adjusted Kappa (PABAK) coefficient for ordinal data (PABAK-OS); dimensional and total score agreement was evaluated based on dichotomous cut-offs for lower well-being, using the PABAK and total, continuous scores were evaluated using Bland-Altman plots. Results Compared to European norms, Swedish children in this sample scored lower on Physical wellbeing (48.8 SE/49.94 EU) but higher on the other KIDSCREEN-27 dimensions: Psychological wellbeing (53.4/49.77), Parent relations and autonomy (55.1/49.99), Social Support and peers (54.1/49.94) and School (55.8/50.01). Older children self-reported lower wellbeing than younger children. No significant self-reported gender differences

  14. Children's Quality of Life Based on the KIDSCREEN-27: Child Self-Report, Parent Ratings and Child-Parent Agreement in a Swedish Random Population Sample.

    Science.gov (United States)

    Berman, Anne H; Liu, Bojing; Ullman, Sara; Jadbäck, Isabel; Engström, Karin

    2016-01-01

    The KIDSCREEN-27 is a measure of child and adolescent quality of life (QoL), with excellent psychometric properties, available in child-report and parent-rating versions in 38 languages. This study provides child-reported and parent-rated norms for the KIDSCREEN-27 among Swedish 11-16 year-olds, as well as child-parent agreement. Sociodemographic correlates of self-reported wellbeing and parent-rated wellbeing were also measured. A random population sample consisting of 600 children aged 11-16, 100 per age group and one of their parents (N = 1200), were approached for response to self-reported and parent-rated versions of the KIDSCREEN-27. Parents were also asked about their education, employment status and their own QoL based on the 26-item WHOQOL-Bref. Based on the final sampling pool of 1158 persons, a 34.8% response rate of 403 individuals was obtained, including 175 child-parent pairs, 27 child singleton responders and 26 parent singletons. Gender and age differences for parent ratings and child-reported data were analyzed using t-tests and the Mann-Whitney U-test. Post-hoc Dunn tests were conducted for pairwise comparisons when the p-value for specific subscales was 0.05 or lower. Child-parent agreement was tested item-by-item, using the Prevalence- and Bias-Adjusted Kappa (PABAK) coefficient for ordinal data (PABAK-OS); dimensional and total score agreement was evaluated based on dichotomous cut-offs for lower well-being, using the PABAK and total, continuous scores were evaluated using Bland-Altman plots. Compared to European norms, Swedish children in this sample scored lower on Physical wellbeing (48.8 SE/49.94 EU) but higher on the other KIDSCREEN-27 dimensions: Psychological wellbeing (53.4/49.77), Parent relations and autonomy (55.1/49.99), Social Support and peers (54.1/49.94) and School (55.8/50.01). Older children self-reported lower wellbeing than younger children. No significant self-reported gender differences occurred and parent ratings showed

  15. Gain in student understanding of the role of random variation in evolution following teaching intervention based on luria-delbruck experiment.

    Science.gov (United States)

    Robson, Rachel L; Burns, Susan

    2011-01-01

    Undergraduate students in introductory biology classes are typically saddled with pre-existing popular beliefs that impede their ability to learn about biological evolution. One of the most common misconceptions about evolution is that the environment causes advantageous mutations, rather than the correct view that mutations occur randomly and the environment only selects for mutants with advantageous traits. In this study, a significant gain in student understanding of the role of randomness in evolution was observed after students participated in an inquiry-based pedagogical intervention based on the Luria-Delbruck experiment. Questionnaires with isomorphic questions regarding environmental selection among random mutants were administered to study participants (N = 82) in five separate sections of a sophomore-level microbiology class before and after the teaching intervention. Demographic data on each participant was also collected, in a way that preserved anonymity. Repeated measures analysis showed that post-test scores were significantly higher than pre-test scores with regard to the questions about evolution (F(1, 77) = 25.913, p evolution had no significant effect on gain in understanding of this concept. This study indicates that conducting and discussing an experiment about phage resistance in E. coli may improve student understanding of the role of stochastic events in evolution more broadly, as post-test answers showed that students were able to apply the lesson of the Luria-Delbruck experiment to other organisms subjected to other kinds of selection.

  16. Interspecific variation in prey capture behavior by co-occurring Nepenthes pitcher plants: evidence for resource partitioning or sampling-scheme artifacts?

    Science.gov (United States)

    Chin, Lijin; Chung, Arthur Y C; Clarke, Charles

    2014-01-01

    Pitcher plants of the genus Nepenthes capture a wide range of arthropod prey for nutritional benefit, using complex combinations of visual and olfactory signals and gravity-driven pitfall trapping mechanisms. In many localities throughout Southeast Asia, several Nepenthes different species occur in mixed populations. Often, the species present at any given location have strongly divergent trap structures and preliminary surveys indicate that different species trap different combinations of arthropod prey, even when growing at the same locality. On this basis, it has been proposed that co-existing Nepenthes species may be engaged in niche segregation with regards to arthropod prey, avoiding direct competition with congeners by deploying traps that have modifications that enable them to target specific prey types. We examined prey capture among 3 multi-species Nepenthes populations in Borneo, finding that co-existing Nepenthes species do capture different combinations of prey, but that significant interspecific variations in arthropod prey combinations can often be detected only at sub-ordinal taxonomic ranks. In all lowland Nepenthes species examined, the dominant prey taxon is Formicidae, but montane Nepenthes trap few (or no) ants and 2 of the 3 species studied have evolved to target alternative sources of nutrition, such as tree shrew feces. Using similarity and null model analyses, we detected evidence for niche segregation with regards to formicid prey among 5 lowland, sympatric Nepenthes species in Sarawak. However, we were unable to determine whether these results provide support for the niche segregation hypothesis, or whether they simply reflect unquantified variation in heterogeneous habitats and/or ant communities in the study sites. These findings are used to propose improvements to the design of field experiments that seek to test hypotheses about targeted prey capture patterns in Nepenthes.

  17. The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormone Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

    Science.gov (United States)

    2013-09-30

    to maintain laboratory consistency. Pregnant animals , identified by ultrasonography , were also excluded from analyses because of hormonal...serum samples have been analyzed by Cornell Animal Health Diagnostic Center (AHDC) Endocrinology Laboratory. Cortisol and reproductive hormone...the reference intervals produced by this study provide the basis for evaluation of animal health that is necessary for future population

  18. Variation in Incentive Effects across Neighbourhoods

    Directory of Open Access Journals (Sweden)

    Mark J Hanly

    2014-03-01

    Full Text Available Small monetary incentives increase survey cooperation rates, however evidence suggests that the appeal of incentives may vary across sample subgroups. Fieldwork budgets can be most effectively distributed by targeting those subgroups where incentives will have the strongest appeal. We examine data from a randomised experiment implemented in the pilot phase of the Irish Longitudinal Study of Ageing, which randomly assigned households to receive a higher (€25 or lower (€10 incentive amount. Using a random effects logistic regression model, we observe a variable effect of the higher incentive across geographic neighbourhoods. The higher incentive has the largest impact in neighbourhoods where baseline cooperation is low, as predicted by Leverage-Saliency theory. Auxiliary neighbourhood-level variables are linked to the sample frame to explore this variation further, however none of these moderate the incentive effect, suggesting that richer information is needed to identify sample subgroups where incentive budgets should be directed.

  19. The clinical and rehabilitative complexity in dementia with Lewy bodies (DLB): experience on a random sample of elderly patients dwelling in an RSA ("Residenza Sanitaria Assistita") of Catania.

    Science.gov (United States)

    Santangelo, Antonino; Testai', Manuela; Albani, Salvatore; Mamazza, Grazia; Pavano, Salvatore; Zuccaro, Carmela; Atteritano, Marco; Berretta, Massimiliano; Tomarchio, Marcello; Maugeri, Domenico

    2010-01-01

    This study was aimed at evaluating the occurrence of DLB in a population sample recovered in assisted sanitary residence (RSA=from the Italian name of "Residenza Sanitaria Assistita") in the Province of Catania. We considered 126 patients from a randomized population recovered in RSA of Viagrande (Catania) in the period from 1st March, 2005 and 31st March, 2007. Those who proved to be demented according to the DSM-III diagnostic protocols, and having a mini mental state examination (MMSE)-score <24 were divided in 2 groups: Group A, all the demented people without the DLB; and Group B, the DLB patients, according to the diagnostic criteria of McKeith. All patients underwent at admission, after 1 month, and at emission the following psychometric and functional tests: MMSE, geriatric depression scale (GDS) [Yesavage J.A., Brink T.L., Rose T.L., Adey M., 1983. The development and validation of geriatric depression screening scale: a preliminary report. J. Psych. Res. 17, 37], Barthel index (BI), activities of daily living (ADL) and instrumental ADL (IADL). Particular attention was dedicated to the presence of delirium during the last 15 days before the admission and during the recovery, the mortality and the prevalence of other complaints. The observed data confirm the prevalence of fragility of DLB patients in 20% of them, a fluctuation of the cognitive capacities, a better recovery of the affectivity, a reduced functional autonomy and autosufficiency. In addition, the DLB patients display a major presence of prevalent delirium, compared to the total population of demented patients, while in this last population only incidental delirium episodes occurred during the recovery period (31.6% vs. 16.6%; p<0.001). In the DLB population decubital lesions occurred more frequently, and were of more severe staging, compared to the controls (45% vs. 27%; p<0.001). Also, the mortality of the DLB patients was higher (about 30% vs. 17% in 12 months). These data confirm the

  20. The influence factors of medical professionalism: A stratified-random sampling study based on the physicians and patients in ambulatory care clinics of Chengdu, China.

    Science.gov (United States)

    Lin, Yifei; Yin, Senlin; Lai, Sike; Tang, Ji; Huang, Jin; Du, Liang

    2016-10-01

    As the relationship between physicians and patients deteriorated in China recently, medical conflicts occurred more frequently now. Physicians, to a certain extent, also take some responsibilities. Awareness of medical professionalism and its influence factors can be helpful to take targeted measures and alleviate the contradiction. Through a combination of physicians' self-assessment and patients' assessment in ambulatory care clinics in Chengdu, this research aims to evaluate the importance of medical professionalism in hospitals and explore the influence factors, hoping to provide decision-making references to improve this grim situation. From February to March, 2013, a cross-sectional study was conducted in 2 tier 3 hospitals, 5 tier 2 hospitals, and 10 community hospitals through a stratified-random sampling method on physicians and patients, at a ratio of 1/5. Questionnaires are adopted from a pilot study. A total of 382 physicians and 1910 patients were matched and surveyed. Regarding the medical professionalism, the scores of the self-assessment for physicians were 85.18 ± 7.267 out of 100 and the scores of patient-assessment were 57.66 ± 7.043 out of 70. The influence factors of self-assessment were physicians' working years (P = 0.003) and patients' complaints (P = 0.006), whereas the influence factors of patient-assessment were patients' ages (P = 0.001) and their physicians' working years (P < 0.01) and satisfaction on the payment mode (P = 0.006). Higher self-assessment on the medical professionalism was in accordance with physicians of more working years and no complaint history. Higher patient-assessment was in line with elder patients, the physicians' more working years, and higher satisfaction on the payment mode. Elder patients, encountering with physicians who worked more years in health care services or with higher satisfaction on the payment mode, contribute to higher scores in patient assessment part. The government should

  1. Work Element B: 157. Sampling in Fish-Bearing Reaches [Variation in Productivity in Headwater Reaches of the Wenatchee Subbasin], Final Report for PNW Research Station.

    Energy Technology Data Exchange (ETDEWEB)

    Polivka, Karl; Bennett, Rita L. [USDA Forest Service, Pacific Northwest Research Station, Wenatchee, WA

    2009-03-31

    We studied variation in productivity in headwater reaches of the Wenatchee subbasin for multiple field seasons with the objective that we could develop methods for monitoring headwater stream conditions at the subcatchment and stream levels, assign a landscape-scale context via the effects of geoclimatic parameters on biological productivity (macroinvertebrates and fish) and use this information to identify how variability in productivity measured in fishless headwaters is transmitted to fish communities in downstream habitats. In 2008, we addressed this final objective. In collaboration with the University of Alaska Fairbanks we found some broad differences in the production of aquatic macroinvertebrates and in fish abundance across categories that combine the effects of climate and management intensity within the subbasin (ecoregions). From a monitoring standpoint, production of benthic macroinvertebrates was not a good predictor of drifting macroinvertebrates and therefore might be a poor predictor of food resources available to fish. Indeed, there is occasionally a correlation between drifting macroinvertebrate abundance and fish abundance which suggests that headwater-derived resources are important. However, fish in the headwaters appeared to be strongly food-limited and there was no evidence that fishless headwaters provided a consistent subsidy to fish in reaches downstream. Fish abundance and population dynamics in first order headwaters may be linked with similar metrics further down the watershed. The relative strength of local dynamics and inputs into productivity may be constrained or augmented by large-scale biogeoclimatic control. Headwater streams are nested within watersheds, which are in turn nested within ecological subregions; thus, we hypothesized that local effects would not necessarily be mutually exclusive from large-scale influence. To test this we examined the density of primarily salmonid fishes at several spatial and temporal scales

  2. Lack of standardization in the procedures for mycological examination of sputum samples from CF patients: a possible cause for variations in the prevalence of filamentous fungi.

    Science.gov (United States)

    Borman, Andrew M; Palmer, Michael D; Delhaes, Laurence; Carrère, Jacqueline; Favennec, Loïc; Ranque, Stéphane; Gangneux, Jean-Pierre; Horré, Regine; Bouchara, Jean-Philippe

    2010-11-01

    Filamentous fungi and yeasts are increasingly isolated from respiratory secretions of patients with cystic fibrosis (CF), and persistent fungal colonization of the airways of such patients is thought to exacerbate lung damage. While many independent studies have identified Aspergillus fumigatus complex as the principal colonizing fungus in CF, increased awareness of the role of fungi in CF pathology coupled with improved mycological culture and identification methods have resulted in a number of other fungi being isolated and reported from CF sputum samples, including A. terreus, members of the Pseudallescheria boydii/Scedosporium apiospermum complex, Exophiala dermatitidis, Paecilomyces and Penicillium species. However, the range of fungal pathogens isolated and the relative prevalence of individual species vary widely between reports from different geographical CF centres, and as yet no standardized method for the mycological examination of CF sputum samples has been adopted. Here, we examine the potential contribution of the mycological methods employed to examine CF respiratory secretions relative to the variability in the fungal biota reported. The role of direct microscopic examination of respiratory samples and the impact of the culture conditions used on the detection of specific fungal pathogens are addressed, and the potential significance of isolation of yeast species from CF patient airways is discussed.

  3. Hourly elemental concentrations in PM2.5 aerosols sampled simultaneously at urban background and road site during SAPUSS – diurnal variations and PMF receptor modelling

    Directory of Open Access Journals (Sweden)

    M. Dall'Osto

    2013-04-01

    Full Text Available Hourly-resolved aerosol chemical speciation data can be a highly powerful tool to determine the source origin of atmospheric pollutants in urban environments. Aerosol mass concentrations of seventeen elements (Na, Mg, Al, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Sr and Pb were obtained by time (1 h and size (PM2.5 particulate matter 2.5 mass fraction simultaneously measured at the UB and RS sites: (1 the regional aerosol sources impact both monitoring sites at similar concentrations regardless their different ventilation conditions; (2 by contrast, local industrial aerosol plumes associated with shipping oil combustion and smelters activities have a higher impact on the more ventilated UB site; (3 a unique source of Pb-Cl (associated with combustion emissions is found to be the major (82% source of fine Cl in the urban agglomerate; (4 the mean diurnal variation of PM2.5 primary traffic non-exhaust brake dust (Fe-Cu suggests that this source is mainly emitted and not resuspended, whereas PM2.5 urban dust (Ca is found mainly resuspended by both traffic vortex and sea breeze; (5 urban dust (Ca is found the aerosol source most affected by land wetness, reduced by a factor of eight during rainy days and suggesting that wet roads may be a solution for reducing urban dust concentrations.

  4. Simulation of variations in the composition of samples in the evaluation of neutral detergent fiber contents by using cellulose standard in filter bags made from different textiles

    OpenAIRE

    Tiago Neves Pereira Valente; Edenio Detmann; Sebastião de Campos Valadares Filho; Mário Fonseca Paulino; Janderson Florêncio Figueiras; Marjorrie Augusto de Souza

    2011-01-01

    The objective of this study was to evaluate the efficiency of using nylon textiles (50 μm), F57 (Ankom®) and non-woven textile (NWT - 100 g/m²) on laboratory evaluation of neutral detergent fiber (NDF) by using quantitative filter paper as purified cellulose standard and by simulating different composition of samples with additions of corn starch, pectin, casein and soybean oil. The quantitative filter paper was processed in a knife mill with a 1-mm screen sieve and the procedures for an...

  5. Review: Use of Asian samples in genetic research of alcohol use disorders: Genetic variation of alcohol metabolizing enzymes and the effects of acetaldehyde.

    Science.gov (United States)

    Matsushita, Sachio; Higuchi, Susumu

    2017-08-01

    Epidemiological studies consistently find that Asian populations report lower rates of alcohol use disorders (AUD) compared with other racial groups. These differences result from a variety of biological, genetic, and environmental influences, some of which are related to the metabolism of alcohol. We will review several studies of these metabolic factors, including several alcohol clamping studies conducted in our laboratory, that provide further insight into the role of the alcohol metabolizing genes and drinking behavior among Japanese drinkers. This manuscript reviewed studies investigating genetic variations of alcohol metabolizing enzymes among Asians and several mechanisms by which these genes are thought to give rise to differences in rates of alcohol dependence. The inactive aldehyde dehydrogenase 2 (ALDH2) and highly active alcohol dehydrogenase-1B (ADH1B) genes are protective factors for the development of AUD. The inactive ALDH2 provides its protective effect through the accumulation of acetaldehyde after consuming alcohol, resulting in unpleasant effects, and heightened sensitivity to alcohol. However, the suppressive effects of inactive ALDH2 and highly active ADH1B for AUDs are only partial and interact with other factors, such as personality traits, psychiatric comorbidities, and environmental factors. While Asians are excellent models for the study of certain genetic effects on the development and consequences of AUD, few clinical studies of this population have been conducted. Further exploration of the interactions between various genetic, individual, and environmental factors influencing drinking behavior and, thus affecting the risk of AUD, would enhance our understanding of how alcohol-related problems develop. The heterozygous ALDH2*1/*2 genotype has only partial effects on limiting drinking behavior, suggesting the potential interaction with other factors. Therefore AUD patients with inactive ALDH2 may be a useful model to identify and to

  6. How changes in depression and anxiety symptoms correspond to variations in female sexual response in a nonclinical sample of young women: a daily diary study.

    Science.gov (United States)

    Kalmbach, David A; Kingsberg, Sheryl A; Ciesla, Jeffrey A

    2014-12-01

    A large body of literature supports the co-occurrence of depression, anxiety, and sexual dysfunction. However, the manner in which affective symptoms map onto specific female sexual response indices is not well understood. The present study aimed to examine changes in depression and anxiety symptoms and their correspondence to fluctuations in desire, subjective arousal, genital response, orgasmic function, and vaginal pain. The study used a 2-week daily diary approach to examine same-day and temporal relations between affective symptoms and sexual function. The unique relations between shared and disorder-specific symptoms of depression and anxiety (i.e., general distress, anhedonia, and anxious arousal) and female sexual response (i.e., desire, subjective arousal, vaginal lubrication, orgasmic function, and sexual pain) were examined, controlling for baseline levels of sexual distress, depression, and anxiety, as well as age effects and menstruation. Analyses revealed that changes in depression and anxiety severity corresponded to same-day variations in sexual response. Specifically, anhedonia (depression-specific symptom) was related to poorer same-day sexual desire, whereas greater anxious arousal (anxiety-specific symptom) was independently related to simultaneous increases in subjective sexual arousal, vaginal lubrication, and sexual pain. Increases in general distress (i.e., shared symptoms) were associated with greater same-day difficulties achieving orgasm. Notably, only one temporal relation was found; it indicated that higher levels of anhedonia predicted a next-day decrease in sexual desire. It is proposed that the simultaneous changes in affective symptoms and sexual function may indicate that they are products of shared underlying mechanisms. That is, in response to stress, the processes manifesting as feelings of weak positive affect and amotivation are the very same processes responsible for diminished capacity for sexual desire. In contrast, the

  7. Simulation of variations in the composition of samples in the evaluation of neutral detergent fiber contents by using cellulose standard in filter bags made from different textiles

    Directory of Open Access Journals (Sweden)

    Tiago Neves Pereira Valente

    2011-07-01

    Full Text Available The objective of this study was to evaluate the efficiency of using nylon textiles (50 μm, F57 (Ankom® and non-woven textile (NWT - 100 g/m² on laboratory evaluation of neutral detergent fiber (NDF by using quantitative filter paper as purified cellulose standard and by simulating different composition of samples with additions of corn starch, pectin, casein and soybean oil. The quantitative filter paper was processed in a knife mill with a 1-mm screen sieve and the procedures for analyses of NDF contents were performed in a fiber analyzer (Ankom220®. Four experiments were carried out with additions of different ingredients into the filter paper: corn starch added at the levels of 15 or 50%; pectin, 15 or 50%; casein, 10 or 30%; and soybean oil at 0, 5, 10, 15, 25 or 50% of dry matter, respectively. The ratio 20 mg of dry matter/cm² of surface was followed. When it was relevant, in function of the evaluated treatments, heat-stable α-amylase was used. The use of F57 and NWT resulted in accurate estimates of NDF contents whereas nylon textile caused loss of insoluble fibrous particles, compromising accuracy of the results. For samples containing starch, use of heat-stable α-amylase is recommended in the evaluation of NDF contents. Pectin and casein are completely solubilized by neutral detergent solution. Levels of oil higher than 10% cause overestimation of NDF contents.

  8. Hydrogeochemical variations in groundwater periodically sampled at El Hierro (Canary Islands) and its relationships with the recent eruptive and unrest periods

    Science.gov (United States)

    Luengo-Oroz, Natividad; Torres, Pedro A.; Moure, David; D'Alessandro, Walter

    2014-05-01

    On 10 October 2011, a submarine volcanic eruption started 2 km south El Hierro Island (Canary Islands, Spain). Since July 2011 a dense multiparametric monitoring network was deployed all over the island by Instituto Geográfico Nacional (IGN). By the time the eruption started, almost 10000 earthquakes had been located and the deformation analyses showed a maximum deformation of more than 5 cm. After the end of the submarine eruption and up to now, several volcanic unrest processes have taken place in the island. The most relevant ones started on June 2012 and March 2013. Each of these periods has been evidenced by intense seismicity and ground deformation. In the framework of this volcanic surveillance program, the IGN team started to periodically sample five groundwater sampling sites. Some parameters have been determined directly in the field (temperature, pH, electric conductivity and alkalinity) and collected samples have been analysed in the laboratory for major (Na, K, NH4, Ca, Mg, SO4, Cl, HCO3, CO3, NO3, NO2, PO4, SiO2, Br, F) and trace elements (Be, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Mo, Ag, Cd, Ba, Hg, Tl, Pb, Th, U) contents. In a few cases samples for the chemical analysis of dissolved gases and for the determination of the isotopic composition of He have been collected at two of the sites. Significant increases in alkalinity have been recorded in all sampling sites correlated both to the eruptive period and also to the following unrest episodes. Such increases are probably related to the dissolution of magmatic CO2 exsolved from the rising magma batches. The magmatic contribution can be confirmed by the isotopic composition of dissolved He showing values in the range from 7.76 to 8.91 R/Ra. Since July 2011, only one important CO2 soil degassing anomaly has been detected. This anomalous flux (620 g/m2.d) was measured in a small area (0.36 km2) before the beginning of the submarine eruption and has not been detected again after the eruption onset

  9. Variations of high frequency parameter of heart rate variability following osteopathic manipulative treatment in healthy subjects compared to control group and sham therapy: randomized controlled trial.

    Science.gov (United States)

    Ruffini, Nuria; D'Alessandro, Giandomenico; Mariani, Nicolò; Pollastrelli, Alberto; Cardinali, Lucia; Cerritelli, Francesco

    2015-01-01

    Heart Rate Variability (HRV) indicates how heart rate changes in response to inner and external stimuli. HRV is linked to health status and it is an indirect marker of the autonomic nervous system (ANS) function. To investigate the influence of osteopathic manipulative treatment (OMT) on cardiac autonomic modulation in healthy subjects, compared with sham therapy and control group. Sixty-six healthy subjects, both male and female, were included in the present 3-armed randomized placebo controlled within subject cross-over single blinded study. Participants were asymptomatic adults (26.7 ± 8.4 y, 51% male, BMI 18.5 ± 4.8), both smokers and non-smokers and not on medications. At enrollment subjects were randomized in three groups: A, B, C. Standardized structural evaluation followed by a patient need-based osteopathic treatment was performed in the first session of group A and in the second session of group B. Standardized evaluation followed by a protocoled sham treatment was provided in the second session of group A and in the first session of group B. No intervention was performed in the two sessions of group C, acting as a time-control. The trial was registered on clinicaltrials.gov identifier: NCT01908920. HRV was calculated from electrocardiography before, during and after the intervention, for a total amount time of 25 min and considering frequency domain as well as linear and non-linear methods as outcome measures. OMT engendered a statistically significant increase of parasympathetic activity, as shown by High Frequency power (p ANS activity increasing parasympathetic function and decreasing sympathetic activity, compared to sham therapy and control group.

  10. Variations of high frequency parameter of heart rate variability following osteopathic manipulative treatment in healthy subjects compared to control group and sham therapy: randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Nuria eRuffini

    2015-08-01

    Full Text Available Context: Heart Rate Variability (HRV indicates how heart rate changes in response to inner and external stimuli. HRV is linked to health status and it is an indirect marker of the autonomic nervous system (ANS function. Objective: To investigate the influence of osteopathic manipulative treatment (OMT on ANS activity through changes of High Frequency, a heart rate variability index indicating the parasympathetic activity, in healthy subjects, compared with sham therapy and control group.Methods: Sixty-six healthy subjects, both male and female, were included in the present 3-armed randomized placebo controlled within subject cross-over single blinded study. Participants were asymptomatic adults, both smokers and non-smokers and not on medications. At enrollment subjects were randomized in 3 groups: A, B, C. Standardized structural evaluation followed by a patient need-based osteopathic treatment was performed in the first session of group A and in the second session of group B. Standardized evaluation followed by a protocoled sham treatment was provided in the second session of group A and in the first session of group B. No intervention was performed in the two sessions of group C, acting as a time-control. The trial was registered on clinicaltrials.gov identifier: NCT01908920.Main Outcomes Measures: HRV was calculated from electrocardiography before, during and after the intervention, for a total amount time of 25 minutes.Results: OMT engendered a statistically significant increase of parasympathetic activity, as shown by High Frequency rate (p<0.001, and decrease of sympathetic activity, as revealed by Low Frequency rate (p<0.01; results also showed a reduction of Low Frequency/High Frequency ratio (p<0.001 and Detrended fluctuation scaling exponent (p<0.05. Conclusions: Findings suggested that OMT can influence ANS activity increasing parasympathetic function and decreasing sympathetic activity, compared to sham therapy and control group.

  11. Intraspecific genetic variation and phylogenetic analysis of Dirofilaria immitis samples from Western China using complete ND1 and 16S rDNA gene sequences.

    Science.gov (United States)

    Liu, Tianyu; Liang, Yinan; Zhong, Xiuqin; Wang, Ning; Hu, Dandan; Zhou, Xuan; Gu, Xiaobin; Peng, Xuerong; Yang, Guangyou

    2014-06-01

    Dirofilaria immitis (heartworm) is the causative agent of an important zoonotic disease that is spread by mosquitoes. In this study, molecular and phylogenetic characterization of D. immitis were performed based on complete ND1 and 16S rDNA gene sequences, which provided the foundation for more advanced molecular diagnosis, prevention, and control of heartworm diseases. The mutation rate and evolutionary divergence in adult heartworm samples from seven dogs in western China were analyzed to obtain information on genetic diversity and variability. Phylogenetic relationships were inferred using both maximum parsimony (MP) and Bayes methods based on the complete gene sequences. The results suggest that D. immitis formed an independent monophyletic group in which the 16S rDNA gene has mutated more rapidly than has ND1. © The American Society of Tropical Medicine and Hygiene.

  12. Individual variation and repeatability of corticosterone responses of little penguins (Eudyptula minor) sampled in two successive years at Oamaru, New Zealand.

    Science.gov (United States)

    Cockrem, John F; Candy, E Jane; Barrett, D Paul; Agnew, Philippa; Potter, Murray A

    2017-04-01

    Plasma corticosterone concentrations increase when birds experience a stressor, and plasma corticosterone responses to a capture and handling stressor have been measured in many species of birds. Whilst it is assumed that the reported corticosterone responses reflect the inherent sensitivity of each bird to the stressor, responses of the same birds have rarely been measured at intervals of one or more years. The current study was conducted to measure the repeatability in two successive years of corticosterone responses of little penguins (Eudyptula minor) at Oamaru, New Zealand. There was a wide range of individual corticosterone responses to capture and restraint in 96 little penguins in 2012 and 50 penguins sampled at the same time of year in 2013. There were significant repeatabilities for the ranks of corticosterone at 15, 30 and 60min (r=0.416±0.160, r=0.636±0.115 and r=0.380±0.166 respectively) and for the ranks of integrated corticosterone responses (r=0.594±0.126) for 23 birds sampled in both years. There were no significant relationships between the size of corticosterone responses and age, body weight or condition index. Mean corticosterone concentrations at 60min were 114.22±6.65ng/ml in 2012 and 116.94±6.42ng/ml in 2013. Mean corticosterone responses did not differ between two successive years and were greater than responses of other penguin species. Penguins are well suited to long term studies in which corticosterone responses are measured annually as potential measures of changing marine environmental conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Variation in the Biochemical Composition of the Edible Seaweed Grateloupia turuturu Yamada Harvested from Two Sampling Sites on the Brittany Coast (France: The Influence of Storage Method on the Extraction of the Seaweed Pigment R-Phycoerythrin

    Directory of Open Access Journals (Sweden)

    Mathilde Munier

    2013-01-01

    Full Text Available Numerous studies have demonstrated that the biochemical content of seaweeds varies according to seasonality in a restricted area. In this study, the influence of sampling site on the biochemical composition of the edible red seaweed Grateloupia turuturu Yamada was investigated, but not its variation over time. Some differences in water-soluble protein ( m dw and  m dw, water-soluble carbohydrate ( m dw and  m dw, and lipid contents ( m dw and  m dw were recorded between the two sites chosen on the Brittany coast (France. The yield of R-phycoerythrin (R-PE contained in the seaweed also varied according to the sampling site ( m dw versus  m dw. In addition, the effect of storage conditions on the preservation of R-PE was studied. The results demonstrated that freezing is the best preservation method in terms of R-PE extraction yield and purity index. In conclusion, this study shows that the sampling site influences the biochemical content of the red seaweed Grateloupia turuturu. Moreover, the extraction yield of R-phycoerythrin and its purity index depend on both the sampling site and the sample storage method.

  14. Variations of high frequency parameter of heart rate variability following osteopathic manipulative treatment in healthy subjects compared to control group and sham therapy: randomized controlled trial

    Science.gov (United States)

    Ruffini, Nuria; D'Alessandro, Giandomenico; Mariani, Nicolò; Pollastrelli, Alberto; Cardinali, Lucia; Cerritelli, Francesco

    2015-01-01

    Context: Heart Rate Variability (HRV) indicates how heart rate changes in response to inner and external stimuli. HRV is linked to health status and it is an indirect marker of the autonomic nervous system (ANS) function. Objective: To investigate the influence of osteopathic manipulative treatment (OMT) on cardiac autonomic modulation in healthy subjects, compared with sham therapy and control group. Methods: Sixty-six healthy subjects, both male and female, were included in the present 3-armed randomized placebo controlled within subject cross-over single blinded study. Participants were asymptomatic adults (26.7 ± 8.4 y, 51% male, BMI 18.5 ± 4.8), both smokers and non-smokers and not on medications. At enrollment subjects were randomized in three groups: A, B, C. Standardized structural evaluation followed by a patient need-based osteopathic treatment was performed in the first session of group A and in the second session of group B. Standardized evaluation followed by a protocoled sham treatment was provided in the second session of group A and in the first session of group B. No intervention was performed in the two sessions of group C, acting as a time-control. The trial was registered on clinicaltrials.gov identifier: NCT01908920. Main Outcomes Measures: HRV was calculated from electrocardiography before, during and after the intervention, for a total amount time of 25 min and considering frequency domain as well as linear and non-linear methods as outcome measures. Results: OMT engendered a statistically significant increase of parasympathetic activity, as shown by High Frequency power (p < 0.001), expressed in normalized and absolute unit, and possibly decrease of sympathetic activity, as revealed by Low Frequency power (p < 0.01); results also showed a reduction of Low Frequency/High Frequency ratio (p < 0.001) and Detrended fluctuation scaling exponent (p < 0.05). Conclusions: Findings suggested that OMT can influence ANS activity increasing

  15. New Results on the Sum of Gamma Random Variates With Application to the Performance of Wireless Communication Systems over Nakagami-m Fading Channels

    CERN Document Server

    Ansari, Imran Shafique; Alouini, Mohamed-Slim; Kucur, Oğuz

    2012-01-01

    The probability density function (PDF) and cumulative distribution function of the sum of L independent but not necessarily identically distributed gamma variates, applicable to the output statistics of maximal ratio combining (MRC) receiver operating over Nakagami-m fading channels or in other words to the statistical analysis of the scenario where the sum of squared Nakagami-m distributions are user-of-interest, is presented in closed-form in terms of well-known Meijer's G function and easily computable Fox's \\={H} function for integer valued and non-integer valued diversity orders (i.e., m fading parameter of Nakagami fading environment), respectively. Further analysis, particularly on bit error rate via PDF-based approach, too is represented in closed form in terms of Meijer's G function and Fox's \\={H} function for integer valued diversity orders, and extended Fox's \\={H} function ($\\hat{H}$) for non-integer valued diversity orders. The proposed results complement previous elegant results that are either...

  16. On the Sum of Gamma Random Variates With Application to the Performance of Maximal Ratio Combining over Nakagami-m Fading Channels

    KAUST Repository

    Ansari, Imran Shafique

    2012-09-08

    The probability distribution function (PDF) and cumulative density function of the sum of L independent but not necessarily identically distributed gamma variates, applicable to maximal ratio combining receiver outputs or in other words applicable to the performance analysis of diversity combining receivers operating over Nakagami-m fading channels, is presented in closed form in terms of Meijer G-function and Fox H-bar-function for integer valued fading parameters and non-integer valued fading parameters, respectively. Further analysis, particularly on bit error rate via PDF-based approach, too is represented in closed form in terms of Meijer G-function and Fox H-bar-function for integer-order fading parameters, and extended Fox H-bar-function (H-hat) for non-integer-order fading parameters. The proposed results complement previous results that are either evolved in closed-form, or expressed in terms of infinite sums or higher order derivatives of the fading parameter m.

  17. High-resolution arrays reveal burden of copy number variations on Parkinson disease genes associated with increased disease risk in random cohorts.

    Science.gov (United States)

    Murthy, Megha N; Veerappa, Avinash M; Seshachalam, Keshava B; Ramachandra, Nallur B

    2016-09-01

    Parkinson disease (PD) is a neurological disease responsible for a considerable rate of mortality and morbidity in the society. Since the symptoms of the disease appear much later than the actual onset of neuron degeneration, a majority of cases remain undiagnosed until the manifestation of the symptoms. In order to investigate the existence of such susceptibility in the population, we analyzed Copy Number Variation (CNV) influences on PD genes in 1715 individuals from 12 different populations. Overall, 16 CNV-PD genes, 3 known to be causal and 13 associated, were found to be significantly enriched. PARK2, was under heavy burden with ~1% of the population containing CNV in the exonic region. The impact of these genes on the genome and disease pathway was analyzed using several genome analysis tools. Protein interaction network of CNV-PD genes revealed a complex interaction of molecules forming a major hub by the α-Synuclein, whose direct interactors, LRRK2, PARK2 and ATP13A2 are under CNV influence. We hypothesize that CNVs may not be the initiating event in the pathogenesis of PD and remain latent until additional secondary hits are acquired and also propose novel genes that may fall under the PD pathway which contribute in pathogenesis.

  18. Variation in Bluetongue virus real-time reverse transcription polymerase chain reaction assay results in blood samples of sheep, cattle, and alpaca.

    Science.gov (United States)

    Brito, Barbara P; Gardner, Ian A; Hietala, Sharon K; Crossley, Beate M

    2011-07-01

    Bluetongue is a vector-borne viral disease that affects domestic and wild ruminants. The epidemiology of this disease has recently changed, with occurrence in new geographic areas. Various real-time quantitative reverse transcription polymerase chain reaction (real-time qRT-PCR) assays are used to detect Bluetongue virus (BTV); however, the impact of biologic differences between New World camelids and domestic ruminant samples on PCR efficiency, for which the BTV real-time qRT-PCR was initially validated are unknown. New world camelids are known to have important biologic differences in whole blood composition, including hemoglobin concentration, which can alter PCR performance. In the present study, sheep, cattle, and alpaca blood were spiked with BTV serotypes 10, 11, 13, and 17 and analyzed in 10-fold dilutions by real-time qRT-PCR to determine if species affected nucleic acid recovery and assay performance. A separate experiment was performed using spiked alpaca blood subsequently diluted in 10-fold series in sheep blood to assess the influence of alpaca blood on performance efficiency of the BTV real-time qRT-PCR assay. Results showed that BTV-specific nucleic acid detection from alpaca blood was consistently 1-2 logs lower than from sheep and cattle blood, and results were similar for each of the 4 BTV serotypes analyzed.

  19. Variations of petrophysical properties and spectral induced polarization in response to drainage and imbibition: a study on a correlated random tube network

    Science.gov (United States)

    Maineult, Alexis; Jougnot, Damien; Revil, André

    2018-02-01

    We implement a procedure to simulate the drainage and imbibition in random, 2-D, square networks. We compute the resistivity index, the relative permeability and the characteristic lengths of a correlated network at various saturation states, under the assumption that the surface conductivity can be neglected. These parameters exhibit a hysteretic behaviour. Then, we calculate the spectral induced polarization (SIP) response of the medium, under the assumption that the electrical impedance of each tube follows a local Warburg conductivity model, with identical DC conductivity and chargeability for all the tubes. We evidence that the shape of the SIP spectra depends on the saturation state. The analysis of the evolution of the macroscopic Cole-Cole parameters of the spectra in function of the saturation also behaves hysteretically, except for the Cole-Cole exponent. We also observe a power-law relationship between the macroscopic DC conductivity and time constant and the relative permeability. We also show that the frequency peak of the phase spectra is directly related to the characteristic length and to the relative permeability, underlining the potential interest of SIP measurements for the estimation of the permeability of unsaturated media.

  20. PREVALENCE OF ANTI- Toxocara ANTIBODIES IN A RANDOM SAMPLE OF INPATIENTS AT A CHILDREN'S HOSPITAL IN VITÓRIA, ESPÍRITO SANTO, BRAZIL

    Directory of Open Access Journals (Sweden)

    Sandra F. MOREIRA-SILVA

    1998-07-01

    Full Text Available In the streets of Vitória, in the State of Espírito Santo, Brazil, are large number of stray dogs, many of which are infected with Toxocara canis, suggesting a high risk for human infection. In order to investigate the prevalence of Toxocara infection in children in Espírito Santo we studied the prevalence of anti-Toxocara antibodies in 100 random inpatients over one year of age, at the Children's Hospital N.S. da Glória, the reference children's hospital for the State.All the sera were collected during the period between October 1996 and January 1997. The mean age was 6.6±4.1 yrs. (1 to 14 yrs., median 6yrs. and there were patients from all of the different wards of the hospital. Sixty-eigth patients came from the metropolitan area of Vitória and the other 32 from 17 other municipalities. The anti-Toxocara antibodies were investigated by ELISA-IgG using a secretory-excretory antigen obtained from second stage larvae. All sera were adsorbed with Ascaris suum antigen before the test. Thirty-nine sera (39% were positive, predominantly from boys, but the gender difference was not statistically significant (boys:25/56 or 44.6%; girls:14/44 or 31.8%; p=0.311. The prevalence of positive sera was higher, but not statistically significant, in children from the urban periphery of metropolitan Vitória (formed by the cities of Vitória, Cariacica, Vila Velha, Serra and Viana than in children from 17 other municipalities (44.1% and 28.1% respectively, p=0.190. Although the samples studied do not represent all children living in the State of Espírito Santo, since the Children's Hospital N.S. da Glória admits only patients from the state health system, it is probable that these results indicate a high frequency of Toxocara infection in children living in Espírito Santo. Further studies of population samples are necessary to ascertain the prevalence of Toxocara infection in our country.Em Vitória é grande o número de cães soltos nas ruas, muitos

  1. Using ecological momentary assessment to investigate short-term variations in sexual functioning in a sample of peri-menopausal women from Iran.

    Directory of Open Access Journals (Sweden)

    Amir H Pakpour

    Full Text Available The investigation of short-term changes in female sexual functioning has received little attention so far. The aims of the study were to gain empirical knowledge on within-subject and within- and across-variable fluctuations in women's sexual functioning over time. More specifically, to investigate the stability of women´s self-reported sexual functioning and the moderating effects of contextual and interpersonal factors. A convenience sample of 206 women, recruited across eight Health care Clinics in Rasht, Iran. Ecological momentary assessment was used to examine fluctuations of sexual functioning over a six week period. A shortened version of the Female Sexual Function Index (FSFI was applied to assess sexual functioning. Self-constructed questions were included to assess relationship satisfaction, partner's sexual performance and stress levels. Mixed linear two-level model analyses revealed a link between orgasm and relationship satisfaction (Beta = 0.125, P = 0.074 with this link varying significantly between women. Analyses further revealed a significant negative association between stress and all six domains of women's sexual functioning. Women not only reported differing levels of stress over the course of the assessment period, but further differed from each other in how much stress they experienced and how much this influenced their sexual response. Orgasm and sexual satisfaction were both significantly associated with all other domains of sexual function (P<0.001. And finally, a link between partner performance and all domains of women`s sexual functioning (P<0.001 could be detected. Except for lubrication (P = 0.717, relationship satisfaction had a significant effect on all domains of the sexual response (P<0.001. Overall, our findings support the new group of criteria introduced in the DSM-5, called "associated features" such as partner factors and relationship factors. Consideration of these criteria is important and necessary for

  2. Using Ecological Momentary Assessment to Investigate Short-Term Variations in Sexual Functioning in a Sample of Peri-Menopausal Women from Iran

    Science.gov (United States)

    Pakpour, Amir H.; Yekaninejad, Mir Saeed; Pallich, Gianandrea; Burri, Andrea

    2015-01-01

    The investigation of short-term changes in female sexual functioning has received little attention so far. The aims of the study were to gain empirical knowledge on within-subject and within- and across-variable fluctuations in women’s sexual functioning over time. More specifically, to investigate the stability of women´s self-reported sexual functioning and the moderating effects of contextual and interpersonal factors. A convenience sample of 206 women, recruited across eight Health care Clinics in Rasht, Iran. Ecological momentary assessment was used to examine fluctuations of sexual functioning over a six week period. A shortened version of the Female Sexual Function Index (FSFI) was applied to assess sexual functioning. Self-constructed questions were included to assess relationship satisfaction, partner’s sexual performance and stress levels. Mixed linear two-level model analyses revealed a link between orgasm and relationship satisfaction (Beta = 0.125, P = 0.074) with this link varying significantly between women. Analyses further revealed a significant negative association between stress and all six domains of women’s sexual functioning. Women not only reported differing levels of stress over the course of the assessment period, but further differed from each other in how much stress they experienced and how much this influenced their sexual response. Orgasm and sexual satisfaction were both significantly associated with all other domains of sexual function (Pwomen`s sexual functioning (P<0.001) could be detected. Except for lubrication (P = 0.717), relationship satisfaction had a significant effect on all domains of the sexual response (P<0.001). Overall, our findings support the new group of criteria introduced in the DSM-5, called “associated features” such as partner factors and relationship factors. Consideration of these criteria is important and necessary for clinicians when diagnosing FSD. PMID:25692787

  3. Random-effects linear modeling and sample size tables for two special crossover designs of average bioequivalence studies: the four-period, two-sequence, two-formulation and six-period, three-sequence, three-formulation designs.

    Science.gov (United States)

    Diaz, Francisco J; Berg, Michel J; Krebill, Ron; Welty, Timothy; Gidal, Barry E; Alloway, Rita; Privitera, Michael

    2013-12-01

    Due to concern and debate in the epilepsy medical community and to the current interest of the US Food and Drug Administration (FDA) in revising approaches to the approval of generic drugs, the FDA is currently supporting ongoing bioequivalence studies of antiepileptic drugs, the EQUIGEN studies. During the design of these crossover studies, the researchers could not find commercial or non-commercial statistical software that quickly allowed computation of sample sizes for their designs, particularly software implementing the FDA requirement of using random-effects linear models for the analyses of bioequivalence studies. This article presents tables for sample-size evaluations of average bioequivalence studies based on the two crossover designs used in the EQUIGEN studies: the four-period, two-sequence, two-formulation design, and the six-period, three-sequence, three-formulation design. Sample-size computations assume that random-effects linear models are used in bioequivalence analyses with crossover designs. Random-effects linear models have been traditionally viewed by many pharmacologists and clinical researchers as just mathematical devices to analyze repeated-measures data. In contrast, a modern view of these models attributes an important mathematical role in theoretical formulations in personalized medicine to them, because these models not only have parameters that represent average patients, but also have parameters that represent individual patients. Moreover, the notation and language of random-effects linear models have evolved over the years. Thus, another goal of this article is to provide a presentation of the statistical modeling of data from bioequivalence studies that highlights the modern view of these models, with special emphasis on power analyses and sample-size computations.

  4. CLOCK gene variation is associated with incidence of type-2 diabetes and cardiovascular diseases in type-2 diabetic subjects: dietary modulation in the PREDIMED randomized trial.

    Science.gov (United States)

    Corella, Dolores; Asensio, Eva M; Coltell, Oscar; Sorlí, José V; Estruch, Ramón; Martínez-González, Miguel Ángel; Salas-Salvadó, Jordi; Castañer, Olga; Arós, Fernando; Lapetra, José; Serra-Majem, Lluís; Gómez-Gracia, Enrique; Ortega-Azorín, Carolina; Fiol, Miquel; Espino, Javier Díez; Díaz-López, Andrés; Fitó, Montserrat; Ros, Emilio; Ordovás, José M

    2016-01-07

    Circadian rhythms regulate key biological processes influencing metabolic pathways. Disregulation is associated with type 2 diabetes (T2D) and cardiovascular diseases (CVD). Circadian rhythms are generated by a transcriptional autoregulatory feedback loop involving core clock genes. CLOCK (circadian locomotor output cycles protein kaput), one of those core genes, is known to regulate glucose metabolism in rodent models. Cross-sectional studies in humans have reported associations between this locus and obesity, plasma glucose, hypertension and T2D prevalence, supporting its role in cardiovascular risk. However, no longitudinal study has investigated the association between CLOCK gene variation and T2D or CVD incidence. Moreover, although in a previous work we detected a gene-diet interaction between the CLOCK-rs4580704 (C > G) single nucleotide polymorphism (SNP) and monounsaturated (MUFA) intake on insulin resistance, no interventional study has analyzed gene-diet interactions on T2D or CVD outcomes. We analyzed the association between the CLOCK-rs4580704 SNP and incidence of T2D and CVD longitudinally in 7098 PREDIMED trial (ISRCTN35739639) participants after a median 4.8-year follow-up. We also examined modulation by Mediterranean diet (MedDiet) intervention (high in MUFA) on these associations. We observed a significant association between the CLOCK-rs4580704 SNP and T2D incidence in n = 3671 non-T2D PREDIMED participants, with variant allele (G) carriers showing decreased incidence (dominant model) compared with CC homozygotes (HR: 0.69; 95 % CI 0.54-0.87; P = 0.002). This protection was more significant in the MedDiet intervention group (HR: 0.58; 95 % CI 0.43-0.78; P CLOCK-rs4580704 SNP and T2D status on stroke. Thus, only in T2D subjects was CLOCK-rs4580704 SNP associated with stroke risk, G-carriers having decreased risk (HR: 0.61; 95 % CI 0.40-0.94; P = 0.024 versus CC) in the multivariable-adjusted model. In agreement with our previous results showing a

  5. Methods and analysis of realizing randomized grouping.

    Science.gov (United States)

    Hu, Liang-Ping; Bao, Xiao-Lei; Wang, Qi

    2011-07-01

    Randomization is one of the four basic principles of research design. The meaning of randomization includes two aspects: one is to randomly select samples from the population, which is known as random sampling; the other is to randomly group all the samples, which is called randomized grouping. Randomized grouping can be subdivided into three categories: completely, stratified and dynamically randomized grouping. This article mainly introduces the steps of complete randomization, the definition of dynamic randomization and the realization of random sampling and grouping by SAS software.

  6. Acceptability, effectiveness, and cost-effectiveness of internet-based exposure treatment for irritable bowel syndrome in a clinical sample: a randomized controlled trial

    OpenAIRE

    Andréewitch Sergej; Lindfors Perjohan; Hedman Erik; Andersson Erik; Andersson Gerhard; Ljótsson Brjánn; Rück Christian; Lindefors Nils

    2011-01-01

    Background: Internet-based cognitive behavior therapy (ICBT) has shown promising effects in the treatment of irritable bowel syndrome (IBS). However, to date no study has used a design where participants have been sampled solely from a clinical population. We aimed to investigate the acceptability, effectiveness, and cost-effectiveness of ICBT for IBS using a consecutively recruited sample from a gastroenterological clinic. less thanbrgreater than less thanbrgreater thanMethods: Sixty-one pat...

  7. A randomized trial found online questionnaires supplemented by postal reminders generated a cost-effective and generalizable sample but don't forget the reminders.

    Science.gov (United States)

    Loban, Amanda; Mandefield, Laura; Hind, Daniel; Bradburn, Mike

    2017-12-01

    The objective of this study was to compare the response rates, data completeness, and representativeness of survey data produced by online and postal surveys. A randomized trial nested within a cohort study in Yorkshire, United Kingdom. Participants were randomized to receive either an electronic (online) survey questionnaire with paper reminder (N = 2,982) or paper questionnaire with electronic reminder (N = 2,855). Response rates were similar for electronic contact and postal contacts (50.9% vs. 49.7%, difference = 1.2%, 95% confidence interval: -1.3% to 3.8%). The characteristics of those responding to the two groups were similar. Participants nevertheless demonstrated an overwhelming preference for postal questionnaires, with the majority responding by post in both groups. Online survey questionnaire systems need to be supplemented with a postal reminder to achieve acceptable uptake, but doing so provides a similar response rate and case mix when compared to postal questionnaires alone. For large surveys, online survey systems may be cost saving. Copyright © 2017 Elsevier Inc. All rights reserved.

  8. Cognitive Interventions for Cognitively Healthy, Mildly Impaired, and Mixed Samples of Older Adults: A Systematic Review and Meta-Analysis of Randomized-Controlled Trials.

    Science.gov (United States)

    Mewborn, Catherine M; Lindbergh, Cutter A; Stephen Miller, L

    2017-12-01

    Cognitive interventions may improve cognition, delay age-related cognitive declines, and improve quality of life for older adults. The current meta-analysis was conducted to update and expand previous work on the efficacy of cognitive interventions for older adults and to examine the impact of key demographic and methodological variables. EBSCOhost and Embase online databases and reference lists were searched to identify relevant randomized-controlled trials (RCTs) of cognitive interventions for cognitively healthy or mildly impaired (MCI) older adults (60+ years). Interventions trained a single cognitive domain (e.g., memory) or were multi-domain training, and outcomes were assessed immediately post-intervention using standard neuropsychological tests. In total, 279 effects from 97 studies were pooled based on a random-effects model and expressed as Hedges' g (unbiased). Overall, results indicated that cognitive interventions produce a small, but significant, improvement in the cognitive functioning of older adults, relative to active and passive control groups (g = 0.298, p < .001, 95% CI = 0.248-0.347). These results were confirmed using multi-level analyses adjusting for nesting of effect sizes within studies (g = 0.362, p < .001, 95% CI = 0.275, 0.449). Age, education, and cognitive status (healthy vs. MCI) were not significant moderators. Working memory interventions proved most effective (g = 0.479), though memory, processing speed, and multi-domain interventions also significantly improved cognition. Effects were larger for directly trained outcomes but were also significant for non-trained outcomes (i.e., "transfer effects"). Implications for future research and clinical practice are discussed. This project was pre-registered with PROSPERO (#42016038386).

  9. The potential of Virtual Reality as anxiety management tool: a randomized controlled study in a sample of patients affected by Generalized Anxiety Disorder

    Directory of Open Access Journals (Sweden)

    Gorini Alessandra

    2008-05-01

    Full Text Available Abstract Background Generalized anxiety disorder (GAD is a psychiatric disorder characterized by a constant and unspecific anxiety that interferes with daily-life activities. Its high prevalence in general population and the severe limitations it causes, point out the necessity to find new efficient strategies to treat it. Together with the cognitive-behavioural treatments, relaxation represents a useful approach for the treatment of GAD, but it has the limitation that it is hard to be learned. To overcome this limitation we propose the use of virtual reality (VR to facilitate the relaxation process by visually presenting key relaxing images to the subjects. The visual presentation of a virtual calm scenario can facilitate patients' practice and mastery of relaxation, making the experience more vivid and real than the one that most subjects can create using their own imagination and memory, and triggering a broad empowerment process within the experience induced by a high sense of presence. According to these premises, the aim of the present study is to investigate the advantages of using a VR-based relaxation protocol in reducing anxiety in patients affected by GAD. Methods/Design The trial is based on a randomized controlled study, including three groups of 25 patients each (for a total of 75 patients: (1 the VR group, (2 the non-VR group and (3 the waiting list (WL group. Patients in the VR group will be taught to relax using a VR relaxing environment and audio-visual mobile narratives; patients in the non-VR group will be taught to relax using the same relaxing narratives proposed to the VR group, but without the VR support, and patients in the WL group will not receive any kind of relaxation training. Psychometric and psychophysiological outcomes will serve as quantitative dependent variables, while subjective reports of participants will be used as qualitative dependent variables. Conclusion We argue that the use of VR for relaxation

  10. Chemical fingerprinting of unevaporated automotive gasoline samples.

    Science.gov (United States)

    Sandercock, P M L; Du Pasquier, E

    2003-06-24

    The comparison of two or more samples of liquid gasoline (petrol) to establish a common origin is a difficult problem in the forensic investigation of arsons and suspicious fires. A total of 35 randomly collected samples of unevaporated gasoline, covering three different grades (regular unleaded, premium unleaded and lead replacement), were examined. The high-boiling fraction of the gasoline was targeted with a view to apply the techniques described herein to evaporated gasoline samples in the future.A novel micro solid phase extraction (SPE) technique using activated alumina was developed to isolate the polar compounds and the polycyclic aromatic hydrocarbons (PAHs) from a 200microl sample of gasoline. Samples were analysed using full-scan gas chromatography-mass spectrometry (GC-MS) and potential target compounds identified. Samples were then re-analysed directly, without prior treatment, using GC-MS in selected ion monitoring (SIM) mode for target compounds that exhibited variation between gasoline samples. Principal component analysis (PCA) was applied to the chromatographic data. The first two principal components (PCs) accounted for 91.5% of the variation in the data. Linear discriminant analysis (LDA) performed on the PCA results showed that the 35 samples tested could be classified into 32 different groups.

  11. Internet-based incentives increase blood glucose testing with a non-adherent, diverse sample of teens with type 1 diabetes mellitus: a randomized controlled Trial.

    Science.gov (United States)

    Raiff, Bethany R; Barrry, Victoria B; Ridenour, Ty A; Jitnarin, Natinee

    2016-06-01

    Non-adherence with self-monitoring blood glucose (SMBG) among teenagers with type 1 diabetes can be a problem. The purpose of this study was to investigate the feasibility, acceptability, and preliminary efficacy of using Internet-based incentives to improve adherence with SMBG in non-adherent teenagers. Participants were randomly assigned to contingent (CS; N = 23), where they had to meet web camera-verified SMBG goals to earn incentives, or non-contingent (NS) groups (N = 18), where they earned incentives independent of adherence. Brief motivational interviewing (MI) was given prior to the intervention. Attrition was 15 % in the CS group. Participants and parents endorsed the intervention on all intervention dimensions. Daily SMBG increased after one MI session, and further increased when incentives were added, but significantly more for so for older participants. SMBG declined slowly over time, but only returned to baseline levels for younger NS participants. Internet-based incentive interventions are feasible, acceptable, and show promise for improving adherence with SMBG.

  12. Parent-Child Associations in Pedometer-Determined Physical Activity and Sedentary Behaviour on Weekdays and Weekends in Random Samples of Families in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Dagmar Sigmundová

    2014-07-01

    Full Text Available This study investigates whether more physically active parents bring up more physically active children and whether parents’ level of physical activity helps children achieve step count recommendations on weekdays and weekends. The participants (388 parents aged 35–45 and their 485 children aged 9–12 were randomly recruited from 21 Czech government-funded primary schools. The participants recorded pedometer step counts for seven days (≥10 h a day during April–May and September–October of 2013. Logistic regression (Enter method was used to examine the achievement of the international recommendations of 11,000 steps/day for girls and 13,000 steps/day for boys. The children of fathers and mothers who met the weekend recommendation of 10,000 steps were 5.48 (95% confidence interval: 1.65; 18.19; p < 0.01 and 3.60 times, respectively (95% confidence interval: 1.21; 10.74; p < 0.05 more likely to achieve the international weekend recommendation than the children of less active parents. The children of mothers who reached the weekday pedometer-based step count recommendation were 4.94 times (95% confidence interval: 1.45; 16.82; p < 0.05 more likely to fulfil the step count recommendation on weekdays than the children of less active mothers.

  13. Probabilistic finite element stiffness of a laterally loaded monopile based on an improved asymptotic sampling method

    DEFF Research Database (Denmark)

    Vahdatirad, Mohammadjavad; Bayat, Mehdi; Andersen, Lars Vabbersgaard

    2015-01-01

    The mechanical responses of an offshore monopile foundation mounted in over-consolidated clay are calculated by employing a stochastic approach where a nonlinear p–y curve is incorporated with a finite element scheme. The random field theory is applied to represent a spatial variation for undrained...... shear strength of clay. Normal and Sobol sampling are employed to provide the asymptotic sampling method to generate the probability distribution of the foundation stiffnesses. Monte Carlo simulation is used as a benchmark. Asymptotic sampling accompanied with Sobol quasi random sampling demonstrates...... an efficient method for estimating the probability distribution of stiffnesses for the offshore monopile foundation....

  14. Major Differences: Variations in Undergraduate and Graduate Student Mental Health and Treatment Utilization across Academic Disciplines

    Science.gov (United States)

    Lipson, Sarah Ketchen; Zhou, Sasha; Wagner, Blake, III; Beck, Katie; Eisenberg, Daniel

    2016-01-01

    This article explores variations in mental health and service utilization across academic disciplines using a random sample of undergraduate and graduate students (N = 64,519) at 81 colleges and universities. We report prevalence of depression, anxiety, suicidality, and self-injury, and rates of help-seeking across disciplines, including results…

  15. Dietary patterns of early childhood and maternal socioeconomic status in a unique prospective sample from a randomized controlled trial of Prenatal DHA Supplementation.

    Science.gov (United States)

    Hidaka, Brandon H; Kerling, Elizabeth H; Thodosoff, Jocelynn M; Sullivan, Debra K; Colombo, John; Carlson, Susan E

    2016-11-25

    Dietary habits established in early childhood and maternal socioeconomic status (SES) are important, complex, interrelated factors that influence a child's growth and development. The aim of this study was to define the major dietary patterns in a cohort of young US children, construct a maternal SES index, and evaluate their associations. The diets of 190 children from a randomized, controlled trial of prenatal supplementation of docosahexaenoic acid (DHA) were recorded at 6-mo intervals from 2-4.5 years by 24-h dietary recall. Hierarchical cluster analysis of age-adjusted, average daily intake of 24 food and beverage groups was used to categorize diet. Unrotated factor analysis generated an SES score from maternal race, ethnicity, age, education, and neighborhood income. We identified two major dietary patterns: "Prudent" and "Western." The 85 (45%) children with a Prudent diet consumed more whole grains, fruit, yogurt and low-fat milk, green and non-starchy vegetables, and nuts and seeds. Conversely, those with a Western diet had greater intake of red meat, discretionary fat and condiments, sweet beverages, refined grains, French fries and potato chips, eggs, starchy vegetables, processed meats, chicken and seafood, and whole-fat milk. Compared to a Western diet, a Prudent diet was associated with one standard deviation higher maternal SES (95% CI: 0.80 to 1.30). We found two major dietary patterns of young US children and defined a single, continuous axis of maternal SES that differed strongly between groups. This is an important first step to investigate how child diet, SES, and prenatal DHA supplementation interact to influence health outcomes. NCT00266825 . Prospectively registered on December 15, 2005.

  16. Extreme values, regular variation and point processes

    CERN Document Server

    Resnick, Sidney I

    1987-01-01

    Extremes Values, Regular Variation and Point Processes is a readable and efficient account of the fundamental mathematical and stochastic process techniques needed to study the behavior of extreme values of phenomena based on independent and identically distributed random variables and vectors It presents a coherent treatment of the distributional and sample path fundamental properties of extremes and records It emphasizes the core primacy of three topics necessary for understanding extremes the analytical theory of regularly varying functions; the probabilistic theory of point processes and random measures; and the link to asymptotic distribution approximations provided by the theory of weak convergence of probability measures in metric spaces The book is self-contained and requires an introductory measure-theoretic course in probability as a prerequisite Almost all sections have an extensive list of exercises which extend developments in the text, offer alternate approaches, test mastery and provide for enj...

  17. Ergodicity of Random Walks on Random DFA

    OpenAIRE

    Balle, Borja

    2013-01-01

    Given a DFA we consider the random walk that starts at the initial state and at each time step moves to a new state by taking a random transition from the current state. This paper shows that for typical DFA this random walk induces an ergodic Markov chain. The notion of typical DFA is formalized by showing that ergodicity holds with high probability when a DFA is sampled uniformly at random from the set of all automata with a fixed number of states. We also show the same result applies to DF...

  18. A random sample survey program of traffic air pollution. Steekproefcontroleprogramma, onderzoek naar luchtverontreiniging door voertuigen in het verkeer; Jaarrapport 1987-1988

    Energy Technology Data Exchange (ETDEWEB)

    Rijkeboer, R.C.; Van Vloten, P.; Schmal, P.

    1988-01-01

    An in-use compliance test with regard to exhaust emissions has been performed by means of a sample of 66 vehicles. Of these vehicles 60 belonged to 12 selected vehicle types (5 vehicles per type) and the other 6 to different types (1 per type). All vehicles complied with EEC Directive 88/76/EEC concerning clean cars and had been sold under the tax incentive scheme for the stimulation of an early introduction of clean cars into the Dutch car fleet. Of the 12 types selected 8 belonged to the class below 1.4 litre. Only 1 of these was fitted with an (open-loop) catalyst. The other 4 types belonged to the class 1.4-2.0 litre; they were all fitted with an open-loop catalyst system. The 6 individual vehicles were all fitted with a closed-loop threeway catalyst. Five belonged to the class 1.4-2.0 litre and one to the class above 2.0 litre. Of these vehicles the exhaust emission was measured in the simulated coldstart urban cycle that forms the basis of the Directive. Additionally measurements were also made in the 'extra-urban driving cycle', that is going to be part of the Directive, in order to gather data. In many cases (so with all catalyst vehicles) a hotstart urban driving cycle was also performed. The vehicles were all checked for a number of adjustment and maintenance aspects. The 12 'complete' types were measured both before and after tuning. The 6 individual vehicles were only measured after tuning. Of 37 vehicles also the emission of noise was determined on the testtrack of the Department of Road Transport in Lelystad.

  19. Experiencing variation

    DEFF Research Database (Denmark)

    Kobayashi, Sofie; Berge, Maria; Grout, Brian William Wilson

    2017-01-01

    This study contributes towards a better understanding of learning dynamics in doctoral supervision by analysing how learning opportunities are created in the interaction between supervisors and PhD students, using the notion of experiencing variation as a key to learning. Empirically, we have bas...... were discussed, created more complex patterns of variation. Both PhD students and supervisors can learn from this. Understanding of this mechanism that creates learning opportunities can help supervisors develop their competences in supervisory pedagogy....

  20. Applications of Asymptotic Sampling on High Dimensional Structural Dynamic Problems

    DEFF Research Database (Denmark)

    Sichani, Mahdi Teimouri; Nielsen, Søren R.K.; Bucher, Christian

    2011-01-01

    The paper represents application of the asymptotic sampling on various structural models subjected to random excitations. A detailed study on the effect of different distributions of the so-called support points is performed. This study shows that the distribution of the support points has...... considerable effect on the final estimations of the method, in particular on the coefficient of variation of the estimated failure probability. Based on these observations, a simple optimization algorithm is proposed which distributes the support points so that the coefficient of variation of the method...... is minimized. Next, the method is applied on different cases of linear and nonlinear systems with a large number of random variables representing the dynamic excitation. The results show that asymptotic sampling is capable of providing good approximations of low failure probability events for very high...

  1. Variation in the annual unsatisfactory rates of selected pathogens and indicators in ready-to-eat food sampled from the point of sale or service in Wales, United Kingdom.

    Science.gov (United States)

    Meldrum, R J; Garside, J; Mannion, P; Charles, D; Ellis, P

    2012-12-01

    The Welsh Food Microbiological Forum "shopping basket" survey is a long running, structured surveillance program examining ready-to-eat food randomly sampled from the point of sale or service in Wales, United Kingdom. The annual unsatisfactory rates for selected indicators and pathogens for 1998 through 2008 were examined. All the annual unsatisfactory rates for the selected pathogens were <0.5%, and no pattern with the annual rate was observed. There was also no discernible trend observed for the annual rates of Listeria spp. (not moncytogenes), with all rates <0.5%. However, there was a trend observed for Esherichia coli, with a decrease in rate between 1998 and 2003, rapid in the first few years, and then a gradual increase in rate up to 2008. It was concluded that there was no discernible pattern to the annual unsatisfactory rates for Listeria spp. (not monocytogenes), L. monocytogenes, Staphylococcus aureus, and Bacillus cereus, but that a definite trend had been observed for E. coli.

  2. Secular trends: a ten-year comparison of the amount and type of physical activity and inactivity of random samples of adolescents in the Czech Republic

    Directory of Open Access Journals (Sweden)

    Frömel Karel

    2011-09-01

    Full Text Available Abstract Background An optimal level of physical activity (PA in adolescence influences the level of PA in adulthood. Although PA declines with age have been demonstrated repeatedly, few studies have been carried out on secular trends. The present study assessed levels, types and secular trends of PA and sedentary behaviour of a sample of adolescents in the Czech Republic. Methods The study comprised two cross-sectional cohorts of adolescents ten years apart. The analysis compared data collected through a week-long monitoring of adolescents' PA in 1998-2000 and 2008-2010. Adolescents wore either Yamax SW-701 or Omron HJ-105 pedometer continuously for 7 days (at least 10 hours per day excluding sleeping, hygiene and bathing. They also recorded their number of steps per day, the type and duration of PA and sedentary behaviour (in minutes on record sheets. In total, 902 adolescents (410 boys; 492 girls aged 14-18 were eligible for analysis. Results Overweight and obesity in Czech adolescents participating in this study increased from 5.5% (older cohort, 1998-2000 to 10.4% (younger cohort, 2008-2010. There were no inter-cohort significant changes in the total amount of sedentary behaviour in boys. However in girls, on weekdays, there was a significant increase in the total duration of sedentary behaviour of the younger cohort (2008-2010 compared with the older one (1998-2000. Studying and screen time (television and computer were among the main sedentary behaviours in Czech adolescents. The types of sedentary behaviour also changed: watching TV (1998-2000 was replaced by time spent on computers (2008-2010. The Czech health-related criterion (achieving 11,000 steps per day decreased only in boys from 68% (1998-2000 to 55% (2008-2010. Across both genders, 55%-75% of Czech adolescents met the health-related criterion of recommended steps per day, however less participants in the younger cohort (2008-2010 met this criterion than in the older cohort

  3. Investigating the Randomness of Numbers

    Science.gov (United States)

    Pendleton, Kenn L.

    2009-01-01

    The use of random numbers is pervasive in today's world. Random numbers have practical applications in such far-flung arenas as computer simulations, cryptography, gambling, the legal system, statistical sampling, and even the war on terrorism. Evaluating the randomness of extremely large samples is a complex, intricate process. However, the…

  4. Diagnostic performance of Schistosoma real-time PCR in urine samples from Kenyan children infected with Schistosoma haematobium: day-to-day variation and follow-up after praziquantel treatment.

    Science.gov (United States)

    Vinkeles Melchers, Natalie V S; van Dam, Govert J; Shaproski, David; Kahama, Anthony I; Brienen, Eric A T; Vennervald, Birgitte J; van Lieshout, Lisette

    2014-04-01

    In an effort to enhance accuracy of diagnosis of Schistosoma haematobium, this study explores day-to-day variability and diagnostic performance of real-time PCR for detection and quantification of Schistosoma DNA compared to other diagnostic tools in an endemic area before and after treatment. Previously collected urine samples (N = 390) from 114 preselected proven parasitological and/or clinical S. haematobium positive Kenyan schoolchildren were analyzed by a Schistosoma internal transcribed spacer-based real-time PCR after 14 years of storage. Pre-treatment day-to-day fluctuations of PCR and microscopy over three consecutive days were measured for 24 children using intra-class correlation coefficient. A combined 'gold standard' (PCR and/or microscopy positive) was used to measure sensitivity and negative predictive value (NPV) of several diagnostic tools at baseline, two and 18 months post-treatment with praziquantel. All 24 repeatedly tested children were PCR-positive over three days with little daily variation in median Ct-values, while 83.3% were found to be egg-positive for S. haematobium at day 1 and 75.0% at day 2 and 3 pre-treatment, signifying daily fluctuations in microscopy diagnosis. Of all 114 preselected schoolchildren, repeated microscopic measurements were required to detect 96.5% versus 100% of positive pre-treatment cases by single PCR. At two months post-treatment, microscopy and PCR detected 22.8% versus 69.3% positive children, respectively. Based on the 'gold standard', PCR showed high sensitivity (>92%) as compared to >31% sensitivity for microscopy, both pre- and post-treatment. Detection and quantification of Schistosoma DNA in urine by real-time PCR was shown to be a powerful and specific diagnostic tool for detection of S. haematobium infections, with less day-to-day variation and higher sensitivity compared to microscopy. The superior performance of PCR before, and two and 18 months post-treatment provides a compelling argument for

  5. Porosity variation in chalk

    DEFF Research Database (Denmark)

    Lind, Ida; Grøn, Peter

    1996-01-01

    Vertical porosity variations in chalk are generally assumed to result from either a vaguely defined combination of primary sedimentary and diagenetic processes or solely to diagenetic processes. In this study, image analysis of backscatter electron images of polished samples and geochemical...

  6. Fluency Variation in Adolescents

    Science.gov (United States)

    De Andrade, Claudia Regina Furquim; Martins, Vanessa De Oliveira

    2007-01-01

    The Speech Fluency Profile of fluent adolescent speakers of Brazilian Portuguese, were examined with respect to gender and neurolinguistic variations. Speech samples of 130 male and female adolescents, aged between 12;0 and 17;11 years were gathered. They were analysed according to type of speech disruption; speech rate; and frequency of speech…

  7. High resolution satellite remote sensing used in a stratified random sampling scheme to quantify the constituent land cover components of the shifting cultivation mosaic of the Democratic Republic of Congo

    Science.gov (United States)

    Molinario, G.; Hansen, M.; Potapov, P.

    2016-12-01

    High resolution satellite imagery obtained from the National Geospatial Intelligence Agency through NASA was used to photo-interpret sample areas within the DRC. The area sampled is a stratifcation of the forest cover loss from circa 2014 that either occurred completely within the previosly mapped homogenous area of the Rural Complex, at it's interface with primary forest, or in isolated forest perforations. Previous research resulted in a map of these areas that contextualizes forest loss depending on where it occurs and with what spatial density, leading to a better understading of the real impacts on forest degradation of livelihood shifting cultivation. The stratified random sampling approach of these areas allows the characterization of the constituent land cover types within these areas, and their variability throughout the DRC. Shifting cultivation has a variable forest degradation footprint in the DRC depending on many factors that drive it, but it's role in forest degradation and deforestation had been disputed, leading us to investigate and quantify the clearing and reuse rates within the strata throughout the country.

  8. The Vermont Diabetes Information System (VDIS): Study Design and Subject Recruitment for a Cluster Randomized Trial of a Decision Support System in a Regional Sample of Primary Care Practices

    Science.gov (United States)

    MacLean, Charles D.; Littenberg, Benjamin; Gagnon, Michael; Reardon, Mimi; Turner, Paul D.; Jordan, Cy

    2008-01-01

    Background Despite evidence that optimal care for diabetes can result in reduced complications and improved economic outcomes, such care is often not achieved. The Vermont Diabetes Information System (VDIS) is a registry-based decision support and reminder system based on the Chronic Care Model and targeted to primary care physicians and their patients with diabetes. Purpose To develop and evaluate a regional decision support system for patients with diabetes. Methods Randomized trial of an information system with clustering at the practice level. Ten percent random sub sample of patients selected for a home interview. Subject and setting includes 10 hospitals, 121 primary care providers, and 7,348 patients in 55 Vermont and New York primary care practices. Results We report on the study design and baseline characteristics of the population. Patients have a mean age of 63 years and a mean glycosolated hemoglobin A1C of 7.1%. Sixty percent of the population has excellent glycemic control (A1C<7%); 45% have excellent lipid control (serum LDL-cholesterol < 100mg/dl and serum triglycerides < 400mg/dl). Twenty-five percent have excellent blood pressure control (<130/80 mm Hg). These results compare favorably to recent national reports. However, only 8% are in optimal control for all three of hyperglycemia, lipids and blood pressure. Conclusions Our experience to date indicates that a low cost decision support and information system based on the chronic care model is feasible in primary care practices that lack sophisticated electronic information systems. VDIS is well accepted by patients, providers, and laboratory staff. If proven beneficial in a rigorous, randomized, controlled evaluation, the intervention could be widely disseminated to practices across America and the world with a substantial impact on the outcomes and costs of diabetes. It could also be adapted to other chronic conditions. We anticipate the results of the study will be available in 2006. PMID

  9. Variational analysis

    CERN Document Server

    Rockafellar, R Tyrrell

    1998-01-01

    From its origins in the minimization of integral functionals, the notion of 'variations' has evolved greatly in connection with applications in optimization, equilibrium, and control. It refers not only to constrained movement away from a point, but also to modes of perturbation and approximation that are best describable by 'set convergence', variational convergence of functions and the like. This book develops a unified framework and, in finite dimension, provides a detailed exposition of variational geometry and subdifferential calculus in their current forms beyond classical and convex analysis. Also covered are set-convergence, set-valued mappings, epi-convergence, duality, maximal monotone mappings, second-order subderivatives, measurable selections and normal integrands. The changes in this 3rd printing mainly concern various typographical corrections, and reference omissions that came to light in the previous printings. Many of these reached the authors' notice through their own re-reading, that of th...

  10. Variational principles

    CERN Document Server

    Moiseiwitsch, B L

    2004-01-01

    This graduate-level text's primary objective is to demonstrate the expression of the equations of the various branches of mathematical physics in the succinct and elegant form of variational principles (and thereby illuminate their interrelationship). Its related intentions are to show how variational principles may be employed to determine the discrete eigenvalues for stationary state problems and to illustrate how to find the values of quantities (such as the phase shifts) that arise in the theory of scattering. Chapter-by-chapter treatment consists of analytical dynamics; optics, wave mecha

  11. Ensembl variation resources

    Directory of Open Access Journals (Sweden)

    Marin-Garcia Pablo

    2010-05-01

    Full Text Available Abstract Background The maturing field of genomics is rapidly increasing the number of sequenced genomes and producing more information from those previously sequenced. Much of this additional information is variation data derived from sampling multiple individuals of a given species with the goal of discovering new variants and characterising the population frequencies of the variants that are already known. These data have immense value for many studies, including those designed to understand evolution and connect genotype to phenotype. Maximising the utility of the data requires that it be stored in an accessible manner that facilitates the integration of variation data with other genome resources such as gene annotation and comparative genomics. Description The Ensembl project provides comprehensive and integrated variation resources for a wide variety of chordate genomes. This paper provides a detailed description of the sources of data and the methods for creating the Ensembl variation databases. It also explores the utility of the information by explaining the range of query options available, from using interactive web displays, to online data mining tools and connecting directly to the data servers programmatically. It gives a good overview of the variation resources and future plans for expanding the variation data within Ensembl. Conclusions Variation data is an important key to understanding the functional and phenotypic differences between individuals. The development of new sequencing and genotyping technologies is greatly increasing the amount of variation data known for almost all genomes. The Ensembl variation resources are integrated into the Ensembl genome browser and provide a comprehensive way to access this data in the context of a widely used genome bioinformatics system. All Ensembl data is freely available at http://www.ensembl.org and from the public MySQL database server at ensembldb.ensembl.org.

  12. A Comparison of the Number of Men Who Have Sex with Men among Rural-To-Urban Migrants with Non-Migrant Rural and Urban Residents in Wuhan, China: A GIS/GPS-Assisted Random Sample Survey Study.

    Directory of Open Access Journals (Sweden)

    Xinguang Chen

    Full Text Available Mobile populations and men who have sex with men (MSM play an increasing role in the current HIV epidemic in China and across the globe. While considerable research has addressed both of these at-risk populations, more effective HIV control requires accurate data on the number of MSM at the population level, particularly MSM among migrant populations.Survey data from a random sample of male rural-to-urban migrants (aged 18-45, n=572 in Wuhan, China were analyzed and compared with those of randomly selected non-migrant urban (n=566 and rural counterparts (580. The GIS/GPS technologies were used for sampling and the survey estimation method was used for data analysis.HIV-related risk behaviors among rural-to-urban migrants were similar to those among the two comparison groups. The estimated proportion of MSM among migrants [95% CI] was 5.8% [4.7, 6.8], higher than 2.8% [1.2, 4.5] for rural residents and 1.0% [0.0, 2.4] for urban residents, respectively. Among these migrants, the MSM were more likely than non-MSM to be older in age, married, and migrated to more cities. They were also more likely to co-habit with others in rental properties located in new town and neighborhoods with fewer old acquaintances and more entertainment establishments. In addition, they were more likely to engage in commercial sex and less likely to consistently use condoms.Findings of this study indicate that compared to rural and urban populations, the migrant population in Wuhan consists of a higher proportion of MSM who also exhibit higher levels of HIV-related risk behaviors. More effective interventions should target this population with a focus on neighborhood factors, social capital and collective efficacy for risk reduction.

  13. RNA-seq: technical variability and sampling

    Science.gov (United States)

    2011-01-01

    Background RNA-seq is revolutionizing the way we study transcriptomes. mRNA can be surveyed without prior knowledge of gene transcripts. Alternative splicing of transcript isoforms and the identification of previously unknown exons are being reported. Initial reports of differences in exon usage, and splicing between samples as well as quantitative differences among samples are beginning to surface. Biological variation has been reported to be larger than technical variation. In addition, technical variation has been reported to be in line with expectations due to random sampling. However, strategies for dealing with technical variation will differ depending on the magnitude. The size of technical variance, and the role of sampling are examined in this manuscript. Results In this study three independent Solexa/Illumina experiments containing technical replicates are analyzed. When coverage is low, large disagreements between technical replicates are apparent. Exon detection between technical replicates is highly variable when the coverage is less than 5 reads per nucleotide and estimates of gene expression are more likely to disagree when coverage is low. Although large disagreements in the estimates of expression are observed at all levels of coverage. Conclusions Technical variability is too high to ignore. Technical variability results in inconsistent detection of exons at low levels of coverage. Further, the estimate of the relative abundance of a transcript can substantially disagree, even when coverage levels are high. This may be due to the low sampling fraction and if so, it will persist as an issue needing to be addressed in experimental design even as the next wave of technology produces larger numbers of reads. We provide practical recommendations for dealing with the technical variability, without dramatic cost increases. PMID:21645359

  14. Association between Dopamine Receptor D2 (DRD2) Variations rs6277 and rs1800497 and Cognitive Performance According to Risk Type for Psychosis: A Nested Case Control Study in a Finnish Population Sample.

    Science.gov (United States)

    Ramsay, Hugh; Barnett, Jennifer H; Miettunen, Jouko; Mukkala, Sari; Mäki, Pirjo; Liuhanen, Johanna; Murray, Graham K; Jarvelin, Marjo-Riitta; Ollila, Hanna; Paunio, Tiina; Veijola, Juha

    2015-01-01

    There is limited research regarding the association between genes and cognitive intermediate phenotypes in those at risk for psychotic disorders. We measured the association between established psychosis risk variants in dopamine D2 receptor (DRD2) and cognitive performance in individuals at age 23 years and explored if associations between cognition and these variants differed according to the presence of familial or clinical risk for psychosis. The subjects of the Oulu Brain and Mind Study were drawn from the general population-based Northern Finland 1986 Birth Cohort (NFBC 1986). Using linear regression, we compared the associations between cognitive performance and two candidate DRD2 polymorphisms (rs6277 and rs1800497) between subjects having familial (n=61) and clinical (n=45) risk for psychosis and a random sample of participating NFBC 1986 controls (n=74). Cognitive performance was evaluated using a comprehensive battery of tests at follow-up. Principal components factor analysis supported a three-factor model for cognitive measures. The minor allele of rs6277 was associated with poorer performance on a verbal factor (p=0.003) but this did not significantly interact with familial or clinical risk for psychosis. The minor allele of rs1800497 was associated with poorer performance on a psychomotor factor (p=0.038), though only in those at familial risk for psychotic disorders (interaction p=0.049). The effect of two DRD2 SNPs on cognitive performance may differ according to risk type for psychosis, suggesting that cognitive intermediate phenotypes differ according to the type (familial or clinical) risk for psychosis.

  15. Fast mixing hyperdynamic sampling

    OpenAIRE

    Sminchisescu, Cristian; Triggs, Bill

    2006-01-01

    Special issue on ECCV'02 papers; International audience; Sequential random sampling (‘Markov Chain Monte-Carlo') is a popular strategy for many vision problems involving multi-modal distributions over high-dimensional parameter spaces. It applies both to importance sampling (where one wants to sample points according to their ‘importance' for some calculation, but otherwise fairly) and to global-optimization (where one wants to find good minima, or at least good starting points for local mini...

  16. Hyperdynamics Importance Sampling

    OpenAIRE

    Sminchisescu, Cristian; Triggs, Bill

    2002-01-01

    International audience; Sequential random sampling (‘Markov Chain Monte-Carlo') is a popular strategy for many vision problems involving multimodal distributions over high-dimensional parameter spaces. It applies both to importance sampling (where one wants to sample points according to their ‘importance' for some calculation, but otherwise fairly) and to global optimization (where one wants to find good minima, or at least good starting points for local minimization, regardless of fairness)....

  17. Concepciones y creencias sobre el trabajo: Estudio descriptivo de algunas fuentes de variación en una muestra laboralmente activa Work Conceptions And Believes: A Descriptive Study On Some Sources Of Variation In A Working Sample

    Directory of Open Access Journals (Sweden)

    Elena Zubieta

    2008-12-01

    Full Text Available Desde una mirada psicosocial, el trabajo consiste en un conjunto de creencias y valores hacia el trabajo que los individuos y grupos sociales desarrollan antes y durante el proceso de socialización en el trabajo. Se trata de un conjunto flexible de cogniciones que está sujeto a cambios dependiendo de las vivencias personales y los cambios contextuales (Salanova, Gracia & Peiró;1996. Desde la perspectiva de la socialización en el trabajo y con el objetivo de explorar en probables fuentes de variación a partir de variables sociodemográficas, contextuales y psicosociales, se desarrolló un estudio descriptivo de diferencias de grupo sobre la base de una muestra no probabilística intencional por cuotas compuesta por 290 sujetos activos laboralmente de la Ciudad de Buenos Aires y el Conurbano Bonaerense. Los resultados muestran la presencia de creencias asociadas a la Ética Protestante del Trabajo y la Competitividad, valores de Apertura al Cambio y Autotrascendencia y configuraciones particulares a partir de introducir variables como el sexo, la edad, el nivel de educación y aspectos de trayectoria laboral tales como años de trabajo, permanencia en la organización y el puesto, interrupciones en la actividad laboral y modalidad de trabajo.From a psycho-sociological view, work can be understood as a set of values and beliefs which individuals and groups construct before and during work process socialization. It is a flexible set of cognitions influenced by individuals personal experiences and contextual changes (Salanova, Gracia & Peiró;1996. Taking socialization at work as a starting point and with the aim of exploring variation sources in terms of sociodemographic, contextual and psycho-sociological variables, a descriptive group differences study was carried out based on a convenience sample of 290 working participants from Buenos Aires city and surroundings. Results show the presence of Protestant Work Ethic, Competitive beliefs, Self

  18. Dealing with daily challenges in dementia (deal-id study): effectiveness of the experience sampling method intervention 'Partner in Sight' for spousal caregivers of people with dementia: design of a randomized controlled trial.

    Science.gov (United States)

    van Knippenberg, Rosalia J M; de Vugt, Marjolein E; Ponds, Rudolf W; Myin-Germeys, Inez; Verhey, Frans R J

    2016-05-11

    There is an urgent need for psychosocial interventions that effectively support dementia caregivers in daily life. The Experience Sampling Methodology (ESM) offers the possibility to provide a more dynamic view of caregiver functioning. ESM-derived feedback may help to redirect caregivers' behavior towards situations that elicit positive emotions and to increase their feelings of competence in the caretaking process. This paper presents the design of a study that evaluates the process characteristics and effects of the ESM-based intervention 'Partner in Sight'. A randomized controlled trial with 90 spousal caregivers of people with dementia will be conducted. Participants will be randomly assigned to the experimental (6-week ESM intervention including feedback), pseudo-experimental (6-week ESM intervention without feedback), or control group (care as usual). Assessments will be performed pre- and post-intervention and at 2-, and 6-month follow-up. Main outcomes will be sense of competence, perceived control, momentary positive affect, and psychological complaints (depressive symptoms, perceived stress, anxiety, momentary negative affect). In addition to the effect evaluation, a process and economic evaluation will be conducted to investigate the credibility and generalizability of the intervention, and its cost-effectiveness. The potential effects of the ESM intervention may help caregivers to endure their care responsibilities and prevent them from becoming overburdened. This is the first ESM intervention for caregivers of people with dementia. The results of this study, therefore, provide a valuable contribution to the growing knowledge on m-health interventions for dementia caregivers. Dutch Trial Register NTR4847 ; date registered Oct 9, 2014.

  19. Latent spatial models and sampling design for landscape genetics

    Science.gov (United States)

    Hanks, Ephraim M.; Hooten, Mevin B.; Knick, Steven T.; Oyler-McCance, Sara J.; Fike, Jennifer A.; Cross, Todd B.; Schwartz, Michael K.

    2016-01-01

    We propose a spatially-explicit approach for modeling genetic variation across space and illustrate how this approach can be used to optimize spatial prediction and sampling design for landscape genetic data. We propose a multinomial data model for categorical microsatellite allele data commonly used in landscape genetic studies, and introduce a latent spatial random effect to allow for spatial correlation between genetic observations. We illustrate how modern dimension reduction approaches to spatial statistics can allow for efficient computation in landscape genetic statistical models covering large spatial domains. We apply our approach to propose a retrospective spatial sampling design for greater sage-grouse (Centrocercus urophasianus) population genetics in the western United States.

  20. Sensitivity analysis of residency and site fidelity estimations to variations in sampling effort and individual catchability Análisis de sensibilidad en estimaciones de residencia y fidelidad al sitio a variaciones en el esfuerzo y capturabilidad individual

    Directory of Open Access Journals (Sweden)

    Eduardo Morteo

    2012-06-01

    Full Text Available Mark-recapture techniques are fundamental for assessing marine mammal population dynamics and individual temporal patterns. Since biases imposed by field conditions are generally unknown, we simulated variations in sampling effort (m and maximum individual catchability (r max to analyze their effects on residency levels measured through the number of recaptures (occurrence, O, duration of stay (permanence, P, and average recurrence (periodicity, I relative to a reference level of exhaustive daily sampling frequency. The number or recorded individuals (Dr was also used to determine the performance of the simulations. Results for standardized (s parameters showed that occurrences (Os were proportional to m and were not influenced by r max. Individual permanence (Ps and individual periodicity (Is were 8-49% and 3-11.74 times lower than expected, respectively, depending on m and r max. Also, Os, Ps, and Is were not influenced by study duration, thus inter-study comparisons are feasible if m and r max are similar. Dr was 68-92% (r max= 0.01 and 1-8% (r max= 1.0 lower than expected depending on m. Longer studies were more accurate but greater effort did not significantly increase Dr estimates. The use of bimonthly sampling frequencies (m= 0.07 was barely accurate and predictions for incomplete datasets were poor. Survey field data were also analyzed from 14 published studies on 4 dolphin species and compared to daily sampling frequencies; resulting values for Os, Ps, and Dr were 62.4-93.3%, 11.6-66.4%, and 2.4-33.8% lower than expected, respectively; also Is was 2.