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Sample records for sampled onemax problem

  1. Optimal resampling for the noisy OneMax problem

    OpenAIRE

    Liu, Jialin; Fairbank, Michael; Pérez-Liébana, Diego; Lucas, Simon M.

    2016-01-01

    The OneMax problem is a standard benchmark optimisation problem for a binary search space. Recent work on applying a Bandit-Based Random Mutation Hill-Climbing algorithm to the noisy OneMax Problem showed that it is important to choose a good value for the resampling number to make a careful trade off between taking more samples in order to reduce noise, and taking fewer samples to reduce the total computational cost. This paper extends that observation, by deriving an analytical expression f...

  2. Optimal mutation rates for the (1+λ) EA on OneMax

    DEFF Research Database (Denmark)

    Gießen, Christian; Witt, Carsten

    2016-01-01

    We study the (1 + λ) EA with mutation probability c/n, where c > 0 is a constant, on the ONEMAX problem. Using an improved variable drift theorem, we show that upper and lower bounds on the expected runtime of the (1+λ) EA obtained from variable drift theorems are at most apart by a small lower...... mutation rates for the (1+λ) EA for various parameter settings of c and λ and also for moderate sizes of n. This makes the need for potentially lengthy and costly experiments in order to optimize the parameters unnecessary. Interestingly, even for moderate n and not too small λ it turns out that mutation...... rates up to 10% larger than the asymptotically optimal rate 1/n minimize the expected runtime. However, in absolute terms the expected runtime does not change by much when replacing 1/n with the optimal mutation rate....

  3. Optimal Mutation Rates for the (1+lambda) EA on OneMax Through Asymptotically Tight Drift Analysis

    DEFF Research Database (Denmark)

    Gießen, Christian; Witt, Carsten

    2018-01-01

    We study the (1+) EA, a classical population-based evolutionary algorithm, with mutation probability c / n, where and are constant, on the benchmark function OneMax, which counts the number of 1-bits in a bitstring. We improve a well-established result that allows to determine the first hitting t...... that mutation rates up to 10% larger than the asymptotically optimal rate 1 / n minimize the expected runtime. However, in absolute terms the expected runtime does not change by much when replacing 1 / n with the optimal mutation rate....... drift is known. This reduces the analysis of expected optimization time to finding an exact expression for the drift. We then give an exact closed-form expression for the drift and develop a method to approximate it very efficiently, enabling us to determine approximate optimal mutation rates for the (1......+) EA for various parameter settings of c and and also for moderate sizes of n. This makes the need for potentially lengthy and costly experiments in order to optimize c for fixed n and for the optimization of OneMax unnecessary. Interestingly, even for moderate n and not too small it turns out...

  4. Population Size vs. Mutation Strength for the (1+λ) EA on OneMax

    DEFF Research Database (Denmark)

    Gießen, Christian; Witt, Carsten

    2015-01-01

    The (1+1) EA with mutation probability c/n, where c>0 is an arbitrary constant, is studied for the classical OneMax function. Its expected optimization time is analyzed exactly (up to lower order terms) as a function of c and λ. It turns out that 1/n is the only optimal mutation probability if λ......=o(ln n ln ln n/ln ln ln n), which is the cut-off point for linear mnspeed-up. However, if λ is above this cut-off point then the standard mutation probability 1/n is no longer the only optimal choice. Instead, the expected number of generations is (up to lower order terms) independent of c...

  5. Lower bounds on the run time of the univariate marginal distribution algorithm on OneMax

    DEFF Research Database (Denmark)

    Krejca, Martin S.; Witt, Carsten

    2017-01-01

    The Univariate Marginal Distribution Algorithm (UMDA), a popular estimation of distribution algorithm, is studied from a run time perspective. On the classical OneMax benchmark function, a lower bound of Ω(μ√n + n log n), where μ is the population size, on its expected run time is proved...... values maintained by the algorithm, including carefully designed potential functions. These techniques may prove useful in advancing the field of run time analysis for estimation of distribution algorithms in general........ This is the first direct lower bound on the run time of the UMDA. It is stronger than the bounds that follow from general black-box complexity theory and is matched by the run time of many evolutionary algorithms. The results are obtained through advanced analyses of the stochastic change of the frequencies of bit...

  6. The Interplay of Population Size and Mutation Probability in the (1+λ) EA on OneMax

    DEFF Research Database (Denmark)

    Gießen, Christian; Witt, Carsten

    2017-01-01

    The ((Formula presented.)) EA with mutation probability c / n, where (Formula presented.) is an arbitrary constant, is studied for the classical OneMax function. Its expected optimization time is analyzed exactly (up to lower order terms) as a function of c and (Formula presented.). It turns out...... that 1 / n is the only optimal mutation probability if (Formula presented.), which is the cut-off point for linear speed-up. However, if (Formula presented.) is above this cut-off point then the standard mutation probability 1 / n is no longer the only optimal choice. Instead, the expected number...... of generations is (up to lower order terms) independent of c, irrespectively of it being less than 1 or greater. The theoretical results are obtained by a careful study of order statistics of the binomial distribution and variable drift theorems for upper and lower bounds. Experimental supplements shed light...

  7. STUDI PERBANDINGAN ANTARA ALGORITMA BIVARIATE MARGINAL DISTRIBUTION DENGAN ALGORITMA GENETIKA

    Directory of Open Access Journals (Sweden)

    Chastine Fatichah

    2006-01-01

    Full Text Available Bivariate Marginal Distribution Algorithm is extended from Estimation of Distribution Algorithm. This heuristic algorithm proposes the new approach for recombination of generate new individual that without crossover and mutation process such as genetic algorithm. Bivariate Marginal Distribution Algorithm uses connectivity variable the pair gene for recombination of generate new individual. Connectivity between variable is doing along optimization process. In this research, genetic algorithm performance with one point crossover is compared with Bivariate Marginal Distribution Algorithm performance in case Onemax, De Jong F2 function, and Traveling Salesman Problem. In this research, experimental results have shown performance the both algorithm is dependence of parameter respectively and also population size that used. For Onemax case with size small problem, Genetic Algorithm perform better with small number of iteration and more fast for get optimum result. However, Bivariate Marginal Distribution Algorithm perform better of result optimization for case Onemax with huge size problem. For De Jong F2 function, Genetic Algorithm perform better from Bivariate Marginal Distribution Algorithm of a number of iteration and time. For case Traveling Salesman Problem, Bivariate Marginal Distribution Algorithm have shown perform better from Genetic Algorithm of optimization result. Abstract in Bahasa Indonesia : Bivariate Marginal Distribution Algorithm merupakan perkembangan lebih lanjut dari Estimation of Distribution Algorithm. Algoritma heuristik ini mengenalkan pendekatan baru dalam melakukan rekombinasi untuk membentuk individu baru, yaitu tidak menggunakan proses crossover dan mutasi seperti pada Genetic Algorithm. Bivariate Marginal Distribution Algorithm menggunakan keterkaitan pasangan variabel dalam melakukan rekombinasi untuk membentuk individu baru. Keterkaitan antar variabel tersebut ditemukan selama proses optimasi berlangsung. Aplikasi yang

  8. Robustness of Populations in Stochastic Environments

    DEFF Research Database (Denmark)

    Gießen, Christian; Kötzing, Timo

    2016-01-01

    We consider stochastic versions of OneMax and LeadingOnes and analyze the performance of evolutionary algorithms with and without populations on these problems. It is known that the (1+1) EA on OneMax performs well in the presence of very small noise, but poorly for higher noise levels. We extend...... the abilities of the (1+1) EA. Larger population sizes are even more beneficial; we consider both parent and offspring populations. In this sense, populations are robust in these stochastic settings....

  9. Robustness of Populations in Stochastic Environments

    DEFF Research Database (Denmark)

    Gießen, Christian; Kötzing, Timo

    2014-01-01

    these results to LeadingOnes and to many different noise models, showing how the application of drift theory can significantly simplify and generalize previous analyses. Most surprisingly, even small populations (of size _(log n)) can make evolutionary algorithms perform well for high noise levels, well outside......We consider stochastic versions of OneMax and Leading-Ones and analyze the performance of evolutionary algorithms with and without populations on these problems. It is known that the (1+1) EA on OneMax performs well in the presence of very small noise, but poorly for higher noise levels. We extend...

  10. ITOUGH2 sample problems

    International Nuclear Information System (INIS)

    Finsterle, S.

    1997-11-01

    This report contains a collection of ITOUGH2 sample problems. It complements the ITOUGH2 User's Guide [Finsterle, 1997a], and the ITOUGH2 Command Reference [Finsterle, 1997b]. ITOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase flow in fractured and porous media [Preuss, 1987, 1991a]. The report ITOUGH2 User's Guide [Finsterle, 1997a] describes the inverse modeling framework and provides the theoretical background. The report ITOUGH2 Command Reference [Finsterle, 1997b] contains the syntax of all ITOUGH2 commands. This report describes a variety of sample problems solved by ITOUGH2. Table 1.1 contains a short description of the seven sample problems discussed in this report. The TOUGH2 equation-of-state (EOS) module that needs to be linked to ITOUGH2 is also indicated. Each sample problem focuses on a few selected issues shown in Table 1.2. ITOUGH2 input features and the usage of program options are described. Furthermore, interpretations of selected inverse modeling results are given. Problem 1 is a multipart tutorial, describing basic ITOUGH2 input files for the main ITOUGH2 application modes; no interpretation of results is given. Problem 2 focuses on non-uniqueness, residual analysis, and correlation structure. Problem 3 illustrates a variety of parameter and observation types, and describes parameter selection strategies. Problem 4 compares the performance of minimization algorithms and discusses model identification. Problem 5 explains how to set up a combined inversion of steady-state and transient data. Problem 6 provides a detailed residual and error analysis. Finally, Problem 7 illustrates how the estimation of model-related parameters may help compensate for errors in that model

  11. Sampling problems for randomly broken sticks

    Energy Technology Data Exchange (ETDEWEB)

    Huillet, Thierry [Laboratoire de Physique Theorique et Modelisation, CNRS-UMR 8089 et Universite de Cergy-Pontoise, 5 mail Gay-Lussac, 95031, Neuville sur Oise (France)

    2003-04-11

    Consider the random partitioning model of a population (represented by a stick of length 1) into n species (fragments) with identically distributed random weights (sizes). Upon ranking the fragments' weights according to ascending sizes, let S{sub m:n} be the size of the mth smallest fragment. Assume that some observer is sampling such populations as follows: drop at random k points (the sample size) onto this stick and record the corresponding numbers of visited fragments. We shall investigate the following sampling problems: (1) what is the sample size if the sampling is carried out until the first visit of the smallest fragment (size S{sub 1:n})? (2) For a given sample size, have all the fragments of the stick been visited at least once or not? This question is related to Feller's random coupon collector problem. (3) In what order are new fragments being discovered and what is the random number of samples separating the discovery of consecutive new fragments until exhaustion of the list? For this problem, the distribution of the size-biased permutation of the species' weights, as the sequence of their weights in their order of appearance is needed and studied.

  12. Biased sampling, over-identified parameter problems and beyond

    CERN Document Server

    Qin, Jing

    2017-01-01

    This book is devoted to biased sampling problems (also called choice-based sampling in Econometrics parlance) and over-identified parameter estimation problems. Biased sampling problems appear in many areas of research, including Medicine, Epidemiology and Public Health, the Social Sciences and Economics. The book addresses a range of important topics, including case and control studies, causal inference, missing data problems, meta-analysis, renewal process and length biased sampling problems, capture and recapture problems, case cohort studies, exponential tilting genetic mixture models etc. The goal of this book is to make it easier for Ph. D students and new researchers to get started in this research area. It will be of interest to all those who work in the health, biological, social and physical sciences, as well as those who are interested in survey methodology and other areas of statistical science, among others. .

  13. Reference Priors For Non-Normal Two-Sample Problems

    NARCIS (Netherlands)

    Fernández, C.; Steel, M.F.J.

    1997-01-01

    The reference prior algorithm (Berger and Bernardo, 1992) is applied to locationscale models with any regular sampling density. A number of two-sample problems is analyzed in this general context, extending the dierence, ratio and product of Normal means problems outside Normality, while explicitly

  14. Simulating quantum correlations as a distributed sampling problem

    International Nuclear Information System (INIS)

    Degorre, Julien; Laplante, Sophie; Roland, Jeremie

    2005-01-01

    It is known that quantum correlations exhibited by a maximally entangled qubit pair can be simulated with the help of shared randomness, supplemented with additional resources, such as communication, postselection or nonlocal boxes. For instance, in the case of projective measurements, it is possible to solve this problem with protocols using one bit of communication or making one use of a nonlocal box. We show that this problem reduces to a distributed sampling problem. We give a new method to obtain samples from a biased distribution, starting with shared random variables following a uniform distribution, and use it to build distributed sampling protocols. This approach allows us to derive, in a simpler and unified way, many existing protocols for projective measurements, and extend them to positive operator value measurements. Moreover, this approach naturally leads to a local hidden variable model for Werner states

  15. Distribution-Preserving Stratified Sampling for Learning Problems.

    Science.gov (United States)

    Cervellera, Cristiano; Maccio, Danilo

    2017-06-09

    The need for extracting a small sample from a large amount of real data, possibly streaming, arises routinely in learning problems, e.g., for storage, to cope with computational limitations, obtain good training/test/validation sets, and select minibatches for stochastic gradient neural network training. Unless we have reasons to select the samples in an active way dictated by the specific task and/or model at hand, it is important that the distribution of the selected points is as similar as possible to the original data. This is obvious for unsupervised learning problems, where the goal is to gain insights on the distribution of the data, but it is also relevant for supervised problems, where the theory explains how the training set distribution influences the generalization error. In this paper, we analyze the technique of stratified sampling from the point of view of distances between probabilities. This allows us to introduce an algorithm, based on recursive binary partition of the input space, aimed at obtaining samples that are distributed as much as possible as the original data. A theoretical analysis is proposed, proving the (greedy) optimality of the procedure together with explicit error bounds. An adaptive version of the algorithm is also introduced to cope with streaming data. Simulation tests on various data sets and different learning tasks are also provided.

  16. Fitness Probability Distribution of Bit-Flip Mutation.

    Science.gov (United States)

    Chicano, Francisco; Sutton, Andrew M; Whitley, L Darrell; Alba, Enrique

    2015-01-01

    Bit-flip mutation is a common mutation operator for evolutionary algorithms applied to optimize functions over binary strings. In this paper, we develop results from the theory of landscapes and Krawtchouk polynomials to exactly compute the probability distribution of fitness values of a binary string undergoing uniform bit-flip mutation. We prove that this probability distribution can be expressed as a polynomial in p, the probability of flipping each bit. We analyze these polynomials and provide closed-form expressions for an easy linear problem (Onemax), and an NP-hard problem, MAX-SAT. We also discuss a connection of the results with runtime analysis.

  17. Problems involved in sampling within and outside zones of emission

    Energy Technology Data Exchange (ETDEWEB)

    Oelschlaeger, W

    1973-01-01

    Problems involved in the sampling of plant materials both inside and outside emission zones are considered, especially in regard to trace element analysis. The basic problem revolves around obtaining as accurately as possible an average sample of actual composition. Elimination of error possibilities requires a knowledge of such factors as botanical composition, vegetation states, rains, mass losses in leaf and blossom parts, contamination through the soil, and gaseous or particulate emissions. Sampling and preparation of samples is also considered with respect to quantitative aspects of trace element analysis.

  18. Adaptive sampling method in deep-penetration particle transport problem

    International Nuclear Information System (INIS)

    Wang Ruihong; Ji Zhicheng; Pei Lucheng

    2012-01-01

    Deep-penetration problem has been one of the difficult problems in shielding calculation with Monte Carlo method for several decades. In this paper, a kind of particle transport random walking system under the emission point as a sampling station is built. Then, an adaptive sampling scheme is derived for better solution with the achieved information. The main advantage of the adaptive scheme is to choose the most suitable sampling number from the emission point station to obtain the minimum value of the total cost in the process of the random walk. Further, the related importance sampling method is introduced. Its main principle is to define the importance function due to the particle state and to ensure the sampling number of the emission particle is proportional to the importance function. The numerical results show that the adaptive scheme under the emission point as a station could overcome the difficulty of underestimation of the result in some degree, and the adaptive importance sampling method gets satisfied results as well. (authors)

  19. Chance constrained problems: penalty reformulation and performance of sample approximation technique

    Czech Academy of Sciences Publication Activity Database

    Branda, Martin

    2012-01-01

    Roč. 48, č. 1 (2012), s. 105-122 ISSN 0023-5954 R&D Projects: GA ČR(CZ) GBP402/12/G097 Institutional research plan: CEZ:AV0Z10750506 Keywords : chance constrained problems * penalty functions * asymptotic equivalence * sample approximation technique * investment problem Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.619, year: 2012 http://library.utia.cas.cz/separaty/2012/E/branda-chance constrained problems penalty reformulation and performance of sample approximation technique.pdf

  20. Solving probabilistic inverse problems rapidly with prior samples

    NARCIS (Netherlands)

    Käufl, Paul; Valentine, Andrew P.; de Wit, Ralph W.; Trampert, Jeannot

    2016-01-01

    Owing to the increasing availability of computational resources, in recent years the probabilistic solution of non-linear, geophysical inverse problems by means of sampling methods has become increasingly feasible. Nevertheless, we still face situations in which a Monte Carlo approach is not

  1. Testing Homogeneity in a Semiparametric Two-Sample Problem

    Directory of Open Access Journals (Sweden)

    Yukun Liu

    2012-01-01

    Full Text Available We study a two-sample homogeneity testing problem, in which one sample comes from a population with density f(x and the other is from a mixture population with mixture density (1−λf(x+λg(x. This problem arises naturally from many statistical applications such as test for partial differential gene expression in microarray study or genetic studies for gene mutation. Under the semiparametric assumption g(x=f(xeα+βx, a penalized empirical likelihood ratio test could be constructed, but its implementation is hindered by the fact that there is neither feasible algorithm for computing the test statistic nor available research results on its theoretical properties. To circumvent these difficulties, we propose an EM test based on the penalized empirical likelihood. We prove that the EM test has a simple chi-square limiting distribution, and we also demonstrate its competitive testing performances by simulations. A real-data example is used to illustrate the proposed methodology.

  2. Problem and Pathological Gambling in a Sample of Casino Patrons

    OpenAIRE

    Fong, Timothy W.; Campos, Michael D.; Brecht, Mary-Lynn; Davis, Alice; Marco, Adrienne; Pecanha, Viviane; Rosenthal, Richard J.

    2010-01-01

    Relatively few studies have examined gambling problems among individuals in a casino setting. The current study sought to examine the prevalence of gambling problems among a sample of casino patrons and examine alcohol and tobacco use, health status, and quality of life by gambling problem status. To these ends, 176 casino patrons were recruited by going to a Southern California casino and requesting that they complete an anonymous survey. Results indicated the following lifetime rates for at...

  3. On the problems of PPS sampling in multi-character surveys ...

    African Journals Online (AJOL)

    This paper, which is on the problems of PPS sampling in multi-character surveys, compares the efficiency of some estimators used in PPSWR sampling for multiple characteristics. From a superpopulation model, we computed the expected variances of the different estimators for each of the first two finite populations ...

  4. Problem and pathological gambling in a sample of casino patrons.

    Science.gov (United States)

    Fong, Timothy W; Campos, Michael D; Brecht, Mary-Lynn; Davis, Alice; Marco, Adrienne; Pecanha, Viviane; Rosenthal, Richard J

    2011-03-01

    Relatively few studies have examined gambling problems among individuals in a casino setting. The current study sought to examine the prevalence of gambling problems among a sample of casino patrons and examine alcohol and tobacco use, health status, and quality of life by gambling problem status. To these ends, 176 casino patrons were recruited by going to a Southern California casino and requesting that they complete an anonymous survey. Results indicated the following lifetime rates for at-risk, problem, and pathological gambling: 29.2, 10.7, and 29.8%. Differences were found with regards to gambling behavior, and results indicated higher rates of smoking among individuals with gambling problems, but not higher rates of alcohol use. Self-rated quality of life was lower among pathological gamblers relative to non-problem gamblers, but did not differ from at-risk or problem gamblers. Although subject to some limitations, our data support the notion of higher frequency of gambling problems among casino patrons and may suggest the need for increased interventions for gambling problems on-site at casinos.

  5. Multi-frequency direct sampling method in inverse scattering problem

    Science.gov (United States)

    Kang, Sangwoo; Lambert, Marc; Park, Won-Kwang

    2017-10-01

    We consider the direct sampling method (DSM) for the two-dimensional inverse scattering problem. Although DSM is fast, stable, and effective, some phenomena remain unexplained by the existing results. We show that the imaging function of the direct sampling method can be expressed by a Bessel function of order zero. We also clarify the previously unexplained imaging phenomena and suggest multi-frequency DSM to overcome traditional DSM. Our method is evaluated in simulation studies using both single and multiple frequencies.

  6. The two-sample problem with induced dependent censorship.

    Science.gov (United States)

    Huang, Y

    1999-12-01

    Induced dependent censorship is a general phenomenon in health service evaluation studies in which a measure such as quality-adjusted survival time or lifetime medical cost is of interest. We investigate the two-sample problem and propose two classes of nonparametric tests. Based on consistent estimation of the survival function for each sample, the two classes of test statistics examine the cumulative weighted difference in hazard functions and in survival functions. We derive a unified asymptotic null distribution theory and inference procedure. The tests are applied to trial V of the International Breast Cancer Study Group and show that long duration chemotherapy significantly improves time without symptoms of disease and toxicity of treatment as compared with the short duration treatment. Simulation studies demonstrate that the proposed tests, with a wide range of weight choices, perform well under moderate sample sizes.

  7. Direct sampling methods for inverse elastic scattering problems

    Science.gov (United States)

    Ji, Xia; Liu, Xiaodong; Xi, Yingxia

    2018-03-01

    We consider the inverse elastic scattering of incident plane compressional and shear waves from the knowledge of the far field patterns. Specifically, three direct sampling methods for location and shape reconstruction are proposed using the different component of the far field patterns. Only inner products are involved in the computation, thus the novel sampling methods are very simple and fast to be implemented. With the help of the factorization of the far field operator, we give a lower bound of the proposed indicator functionals for sampling points inside the scatterers. While for the sampling points outside the scatterers, we show that the indicator functionals decay like the Bessel functions as the sampling point goes away from the boundary of the scatterers. We also show that the proposed indicator functionals continuously dependent on the far field patterns, which further implies that the novel sampling methods are extremely stable with respect to data error. For the case when the observation directions are restricted into the limited aperture, we firstly introduce some data retrieval techniques to obtain those data that can not be measured directly and then use the proposed direct sampling methods for location and shape reconstructions. Finally, some numerical simulations in two dimensions are conducted with noisy data, and the results further verify the effectiveness and robustness of the proposed sampling methods, even for multiple multiscale cases and limited-aperture problems.

  8. Comparison between correlated sampling and the perturbation technique of MCNP5 for fixed-source problems

    International Nuclear Information System (INIS)

    He Tao; Su Bingjing

    2011-01-01

    Highlights: → The performance of the MCNP differential operator perturbation technique is compared with that of the MCNP correlated sampling method for three types of fixed-source problems. → In terms of precision, the MCNP perturbation technique outperforms correlated sampling for one type of problem but performs comparably with or even under-performs correlated sampling for the other two types of problems. → In terms of accuracy, the MCNP perturbation calculations may predict inaccurate results for some of the test problems. However, the accuracy can be improved if the midpoint correction technique is used. - Abstract: Correlated sampling and the differential operator perturbation technique are two methods that enable MCNP (Monte Carlo N-Particle) to simulate small response change between an original system and a perturbed system. In this work the performance of the MCNP differential operator perturbation technique is compared with that of the MCNP correlated sampling method for three types of fixed-source problems. In terms of precision of predicted response changes, the MCNP perturbation technique outperforms correlated sampling for the problem involving variation of nuclide concentrations in the same direction but performs comparably with or even underperforms correlated sampling for the other two types of problems that involve void or variation of nuclide concentrations in opposite directions. In terms of accuracy, the MCNP differential operator perturbation calculations may predict inaccurate results that deviate from the benchmarks well beyond their uncertainty ranges for some of the test problems. However, the accuracy of the MCNP differential operator perturbation can be improved if the midpoint correction technique is used.

  9. On the Use of Importance Sampling in Particle Transport Problems

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, B

    1965-06-15

    The idea of importance sampling is applied to the problem of solving integral equations of Fredholm's type. Especially Bolzmann's neutron transport equation is taken into consideration. For the solution of the latter equation, an importance sampling technique is derived from some simple transformations at the original transport equation into a similar equation. Examples of transformations are given, which have been used with great success in practice.

  10. On the Use of Importance Sampling in Particle Transport Problems

    International Nuclear Information System (INIS)

    Eriksson, B.

    1965-06-01

    The idea of importance sampling is applied to the problem of solving integral equations of Fredholm's type. Especially Bolzmann's neutron transport equation is taken into consideration. For the solution of the latter equation, an importance sampling technique is derived from some simple transformations at the original transport equation into a similar equation. Examples of transformations are given, which have been used with great success in practice

  11. ON SAMPLING BASED METHODS FOR THE DUBINS TRAVELING SALESMAN PROBLEM WITH NEIGHBORHOODS

    Directory of Open Access Journals (Sweden)

    Petr Váňa

    2015-12-01

    Full Text Available In this paper, we address the problem of path planning to visit a set of regions by Dubins vehicle, which is also known as the Dubins Traveling Salesman Problem Neighborhoods (DTSPN. We propose a modification of the existing sampling-based approach to determine increasing number of samples per goal region and thus improve the solution quality if a more computational time is available. The proposed modification of the sampling-based algorithm has been compared with performance of existing approaches for the DTSPN and results of the quality of the found solutions and the required computational time are presented in the paper.

  12. The electron transport problem sampling by Monte Carlo individual collision technique

    International Nuclear Information System (INIS)

    Androsenko, P.A.; Belousov, V.I.

    2005-01-01

    The problem of electron transport is of most interest in all fields of the modern science. To solve this problem the Monte Carlo sampling has to be used. The electron transport is characterized by a large number of individual interactions. To simulate electron transport the 'condensed history' technique may be used where a large number of collisions are grouped into a single step to be sampled randomly. Another kind of Monte Carlo sampling is the individual collision technique. In comparison with condensed history technique researcher has the incontestable advantages. For example one does not need to give parameters altered by condensed history technique like upper limit for electron energy, resolution, number of sub-steps etc. Also the condensed history technique may lose some very important tracks of electrons because of its limited nature by step parameters of particle movement and due to weakness of algorithms for example energy indexing algorithm. There are no these disadvantages in the individual collision technique. This report presents some sampling algorithms of new version BRAND code where above mentioned technique is used. All information on electrons was taken from Endf-6 files. They are the important part of BRAND. These files have not been processed but directly taken from electron information source. Four kinds of interaction like the elastic interaction, the Bremsstrahlung, the atomic excitation and the atomic electro-ionization were considered. In this report some results of sampling are presented after comparison with analogs. For example the endovascular radiotherapy problem (P2) of QUADOS2002 was presented in comparison with another techniques that are usually used. (authors)

  13. Privacy problems in the small sample selection

    Directory of Open Access Journals (Sweden)

    Loredana Cerbara

    2013-05-01

    Full Text Available The side of social research that uses small samples for the production of micro data, today finds some operating difficulties due to the privacy law. The privacy code is a really important and necessary law because it guarantees the Italian citizen’s rights, as already happens in other Countries of the world. However it does not seem appropriate to limit once more the possibilities of the data production of the national centres of research. That possibilities are already moreover compromised due to insufficient founds is a common problem becoming more and more frequent in the research field. It would be necessary, therefore, to include in the law the possibility to use telephonic lists to select samples useful for activities directly of interest and importance to the citizen, such as the collection of the data carried out on the basis of opinion polls by the centres of research of the Italian CNR and some universities.

  14. A direct sampling method to an inverse medium scattering problem

    KAUST Repository

    Ito, Kazufumi; Jin, Bangti; Zou, Jun

    2012-01-01

    In this work we present a novel sampling method for time harmonic inverse medium scattering problems. It provides a simple tool to directly estimate the shape of the unknown scatterers (inhomogeneous media), and it is applicable even when

  15. Marine sampling in Malaysia coastal area: the challenge, problems and solution

    International Nuclear Information System (INIS)

    Norfaizal Mohamed; Khairul Nizam Razali; Mohd Rafaie Mohd Murtadza; Muhammad Amin Abdul Ghani; Zaharudin Ahmad; Abdul Kadir Ishak

    2005-01-01

    Malaysia Marine Radioactivity Database Development Project is one of the five research contracts that was signed between MINT and AELB. Three marine sampling expeditions had been carried out using K.L. PAUS vessel owned by Malaysian Fisheries Institute, Chendering, Terengganu. The first marine sampling expedition was taken place at East Coast Peninsular Malaysia waters on August 2003, followed on February 2004 at West Coast Peninsular Malaysia waters, and lastly at Sarawak-Sabah waters on July 2004. Many challenges and problems were faced when collecting sediment, water, biota and plankton sample during this marine sampling. (Author)

  16. The electron transport problem sampling by Monte Carlo individual collision technique

    Energy Technology Data Exchange (ETDEWEB)

    Androsenko, P.A.; Belousov, V.I. [Obninsk State Technical Univ. of Nuclear Power Engineering, Kaluga region (Russian Federation)

    2005-07-01

    The problem of electron transport is of most interest in all fields of the modern science. To solve this problem the Monte Carlo sampling has to be used. The electron transport is characterized by a large number of individual interactions. To simulate electron transport the 'condensed history' technique may be used where a large number of collisions are grouped into a single step to be sampled randomly. Another kind of Monte Carlo sampling is the individual collision technique. In comparison with condensed history technique researcher has the incontestable advantages. For example one does not need to give parameters altered by condensed history technique like upper limit for electron energy, resolution, number of sub-steps etc. Also the condensed history technique may lose some very important tracks of electrons because of its limited nature by step parameters of particle movement and due to weakness of algorithms for example energy indexing algorithm. There are no these disadvantages in the individual collision technique. This report presents some sampling algorithms of new version BRAND code where above mentioned technique is used. All information on electrons was taken from Endf-6 files. They are the important part of BRAND. These files have not been processed but directly taken from electron information source. Four kinds of interaction like the elastic interaction, the Bremsstrahlung, the atomic excitation and the atomic electro-ionization were considered. In this report some results of sampling are presented after comparison with analogs. For example the endovascular radiotherapy problem (P2) of QUADOS2002 was presented in comparison with another techniques that are usually used. (authors)

  17. Parent-reported feeding and feeding problems in a sample of Dutch toddlers

    NARCIS (Netherlands)

    Moor, J.M.H. de; Didden, H.C.M.; Korzilius, H.P.L.M.

    2007-01-01

    Little is known about the feeding behaviors and problems with feeding in toddlers. In the present questionnaire study, data were collected on the feeding behaviors and feeding problems in a relatively large (n = 422) sample of Dutch healthy toddlers (i.e. 18-36 months old) who lived at home with

  18. Toward a mathematical theory of environmental monitoring: the infrequent sampling problem

    International Nuclear Information System (INIS)

    Pimentel, K.D.

    1975-06-01

    Optimal monitoring of pollutants in diffusive environmental media was studied in the contexts of the subproblems of the optimal design and management of environmental monitors for bounds on maximum allowable errors in the estimate of the monitor state or output variables. Concise problem statements were made. Continuous-time finite-dimensional normal mode models for distributed stochastic diffusive pollutant transport were developed. The resultant set of state equations was discretized in time for implementation in the Kalman Filter in the problem of optimal state estimation. The main results of this thesis concern the special class of optimal monitoring problem called the infrequent sampling problem. Extensions to systems including pollutant scavenging and systems with emission or radiation boundary conditions were made. (U.S.)

  19. NASTRAN thermal analyzer: Theory and application including a guide to modeling engineering problems, volume 2. [sample problem library guide

    Science.gov (United States)

    Jackson, C. E., Jr.

    1977-01-01

    A sample problem library containing 20 problems covering most facets of Nastran Thermal Analyzer modeling is presented. Areas discussed include radiative interchange, arbitrary nonlinear loads, transient temperature and steady-state structural plots, temperature-dependent conductivities, simulated multi-layer insulation, and constraint techniques. The use of the major control options and important DMAP alters is demonstrated.

  20. Sample problem calculations related to two-phase flow transients in a PWR relief-piping network

    International Nuclear Information System (INIS)

    Shin, Y.W.; Wiedermann, A.H.

    1981-03-01

    Two sample problems related with the fast transients of water/steam flow in the relief line of a PWR pressurizer were calculated with a network-flow analysis computer code STAC (System Transient-Flow Analysis Code). The sample problems were supplied by EPRI and are designed to test computer codes or computational methods to determine whether they have the basic capability to handle the important flow features present in a typical relief line of a PWR pressurizer. It was found necessary to implement into the STAC code a number of additional boundary conditions in order to calculate the sample problems. This includes the dynamics of the fluid interface that is treated as a moving boundary. This report describes the methodologies adopted for handling the newly implemented boundary conditions and the computational results of the two sample problems. In order to demonstrate the accuracies achieved in the STAC code results, analytical solutions are also obtained and used as a basis for comparison

  1. Recent bibliography on analytical and sampling problems of a PWR primary coolant

    International Nuclear Information System (INIS)

    Illy, H.

    1980-07-01

    An extensive bibliography on the problems of analysis and sampling of the primary cooling water of PWRs is presented. The aim was to collect the analytical methods for dissolved gases. The sampling and preparation are also taken into account. last 8-10 years is included. The bibliography is arranged into alphabetical order by topics. The most important topics are as follows: boric acid, gas analysis, hydrogen isotopes, iodine, noble gases, radiation monitoring, sampling and preparation, water chemistry. (R.J.)

  2. Virtual sampling in variational processing of Monte Carlo simulation in a deep neutron penetration problem

    International Nuclear Information System (INIS)

    Allagi, Mabruk O.; Lewins, Jeffery D.

    1999-01-01

    In a further study of virtually processed Monte Carlo estimates in neutron transport, a shielding problem has been studied. The use of virtual sampling to estimate the importance function at a certain point in the phase space depends on the presence of neutrons from the real source at that point. But in deep penetration problems, not many neutrons will reach regions far away from the source. In order to overcome this problem, two suggestions are considered: (1) virtual sampling is used as far as the real neutrons can reach, then fictitious sampling is introduced for the remaining regions, distributed in all the regions, or (2) only one fictitious source is placed where the real neutrons almost terminate and then virtual sampling is used in the same way as for the real source. Variational processing is again found to improve the Monte Carlo estimates, being best when using one fictitious source in the far regions with virtual sampling (option 2). When fictitious sources are used to estimate the importances in regions far away from the source, some optimization has to be performed for the proportion of fictitious to real sources, weighted against accuracy and computational costs. It has been found in this study that the optimum number of cells to be treated by fictitious sampling is problem dependent, but as a rule of thumb, fictitious sampling should be employed in regions where the number of neutrons from the real source fall below a specified limit for good statistics

  3. The Impact of Parametrization on Randomized Search Heuristics

    DEFF Research Database (Denmark)

    Gießen, Christian

    with mutation probability c/n on ONEMAX, where c > 0 and λ are constant. We present an improved variable drift theorem that weakens the requirement that no large steps towards the optimum may occur in the process to a stochastic one, reducing the analysis of the expected optimization time to finding an exact...... algorithms. It consists of creating half the offspring with a higher and the rest with a lower mutation rate. The mutation rate is then adjusted, based on the success of the subpopulations. We show that the (1+λ) EA optimizes ONEMAX in an expected optimization time of O(nλ/logλ + nlogn) which has been shown...... evaluation. On classical test functions, such noise makes optimization by the simple (1+1) EA hillclimber infeasible even in exponential time. Interestingly, the use of parent and offspring populations of only logarithmic size turns the algorithm into an efficient one. The results are obtained by drift...

  4. Problem Gambling in a Sample of Older Adult Casino Gamblers.

    Science.gov (United States)

    van der Maas, Mark; Mann, Robert E; McCready, John; Matheson, Flora I; Turner, Nigel E; Hamilton, Hayley A; Schrans, Tracy; Ialomiteanu, Anca

    2017-01-01

    As older adults continue to make up a greater proportion of the Canadian population, it becomes more important to understand the implications that their leisure activities have for their physical and mental health. Gambling, in particular, is a form of leisure that is becoming more widely available and has important implications for the mental health and financial well-being of older adults. This study examines a large sample (2103) of casino-going Ontarian adults over the age of 55 and identifies those features of their gambling participation that are associated with problem gambling. Logistic regression analysis is used to analyze the data. Focusing on types of gambling participated in and motivations for visiting the casino, this study finds that several forms of gambling and motivations to gamble are associated with greater risk of problem gambling. It also finds that some motivations are associated with lower risk of problem gambling. The findings of this study have implications related to gambling availability within an aging population.

  5. Exploring the Connection Between Sampling Problems in Bayesian Inference and Statistical Mechanics

    Science.gov (United States)

    Pohorille, Andrew

    2006-01-01

    The Bayesian and statistical mechanical communities often share the same objective in their work - estimating and integrating probability distribution functions (pdfs) describing stochastic systems, models or processes. Frequently, these pdfs are complex functions of random variables exhibiting multiple, well separated local minima. Conventional strategies for sampling such pdfs are inefficient, sometimes leading to an apparent non-ergodic behavior. Several recently developed techniques for handling this problem have been successfully applied in statistical mechanics. In the multicanonical and Wang-Landau Monte Carlo (MC) methods, the correct pdfs are recovered from uniform sampling of the parameter space by iteratively establishing proper weighting factors connecting these distributions. Trivial generalizations allow for sampling from any chosen pdf. The closely related transition matrix method relies on estimating transition probabilities between different states. All these methods proved to generate estimates of pdfs with high statistical accuracy. In another MC technique, parallel tempering, several random walks, each corresponding to a different value of a parameter (e.g. "temperature"), are generated and occasionally exchanged using the Metropolis criterion. This method can be considered as a statistically correct version of simulated annealing. An alternative approach is to represent the set of independent variables as a Hamiltonian system. Considerab!e progress has been made in understanding how to ensure that the system obeys the equipartition theorem or, equivalently, that coupling between the variables is correctly described. Then a host of techniques developed for dynamical systems can be used. Among them, probably the most powerful is the Adaptive Biasing Force method, in which thermodynamic integration and biased sampling are combined to yield very efficient estimates of pdfs. The third class of methods deals with transitions between states described

  6. 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 consid...... dimensional reliability problems in structural dynamics.......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...... 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...

  7. Improving Creative Problem-Solving in a Sample of Third Culture Kids

    Science.gov (United States)

    Lee, Young Ju; Bain, Sherry K.; McCallum, R. Steve

    2007-01-01

    We investigated the effects of divergent thinking training (with explicit instruction) on problem-solving tasks in a sample of Third Culture Kids (Useem and Downie, 1976). We were specifically interested in whether the children's originality and fluency in responding increased following instruction, not only on classroom-based worksheets and the…

  8. Symptoms and problems in a nationally representative sample of advanced cancer patients

    DEFF Research Database (Denmark)

    Johnsen, Anna Thit; Petersen, Morten Aagaard; Pedersen, Lise

    2009-01-01

    Little is known about the need for palliative care among advanced cancer patients who are not in specialist palliative care. The purpose was to identify prevalence and predictors of symptoms and problems in a nationally representative sample of Danish advanced cancer patients. Patients with cancer...... or not were associated with several symptoms and problems. This is probably the first nationally representative study of its kind. It shows that advanced cancer patients in Denmark have symptoms and problems that deserve attention and that some patient groups are especially at risk....... predictors. In total, 977 (60%) patients participated. The most frequent symptoms/problems were fatigue (57%; severe 22%) followed by reduced role function, insomnia and pain. Age, cancer stage, primary tumour, type of department, marital status and whether the patient had recently been hospitalized...

  9. Inverse problems with non-trivial priors: efficient solution through sequential Gibbs sampling

    DEFF Research Database (Denmark)

    Hansen, Thomas Mejer; Cordua, Knud Skou; Mosegaard, Klaus

    2012-01-01

    Markov chain Monte Carlo methods such as the Gibbs sampler and the Metropolis algorithm can be used to sample solutions to non-linear inverse problems. In principle, these methods allow incorporation of prior information of arbitrary complexity. If an analytical closed form description of the prior...... is available, which is the case when the prior can be described by a multidimensional Gaussian distribution, such prior information can easily be considered. In reality, prior information is often more complex than can be described by the Gaussian model, and no closed form expression of the prior can be given....... We propose an algorithm, called sequential Gibbs sampling, allowing the Metropolis algorithm to efficiently incorporate complex priors into the solution of an inverse problem, also for the case where no closed form description of the prior exists. First, we lay out the theoretical background...

  10. Advanced Curation: Solving Current and Future Sample Return Problems

    Science.gov (United States)

    Fries, M.; Calaway, M.; Evans, C.; McCubbin, F.

    2015-01-01

    Advanced Curation is a wide-ranging and comprehensive research and development effort at NASA Johnson Space Center that identifies and remediates sample related issues. For current collections, Advanced Curation investigates new cleaning, verification, and analytical techniques to assess their suitability for improving curation processes. Specific needs are also assessed for future sample return missions. For each need, a written plan is drawn up to achieve the requirement. The plan draws while upon current Curation practices, input from Curators, the analytical expertise of the Astromaterials Research and Exploration Science (ARES) team, and suitable standards maintained by ISO, IEST, NIST and other institutions. Additionally, new technologies are adopted on the bases of need and availability. Implementation plans are tested using customized trial programs with statistically robust courses of measurement, and are iterated if necessary until an implementable protocol is established. Upcoming and potential NASA missions such as OSIRIS-REx, the Asteroid Retrieval Mission (ARM), sample return missions in the New Frontiers program, and Mars sample return (MSR) all feature new difficulties and specialized sample handling requirements. The Mars 2020 mission in particular poses a suite of challenges since the mission will cache martian samples for possible return to Earth. In anticipation of future MSR, the following problems are among those under investigation: What is the most efficient means to achieve the less than 1.0 ng/sq cm total organic carbon (TOC) cleanliness required for all sample handling hardware? How do we maintain and verify cleanliness at this level? The Mars 2020 Organic Contamination Panel (OCP) predicts that organic carbon, if present, will be present at the "one to tens" of ppb level in martian near-surface samples. The same samples will likely contain wt% perchlorate salts, or approximately 1,000,000x as much perchlorate oxidizer as organic carbon

  11. The association between childhood maltreatment and gambling problems in a community sample of adult men and women.

    Science.gov (United States)

    Hodgins, David C; Schopflocher, Don P; el-Guebaly, Nady; Casey, David M; Smith, Garry J; Williams, Robert J; Wood, Robert T

    2010-09-01

    The association between childhood maltreatment and gambling problems was examined in a community sample of men and women (N = 1,372). As hypothesized, individuals with gambling problems reported greater childhood maltreatment than individuals without gambling problems. Childhood maltreatment predicted severity of gambling problems and frequency of gambling even when other individual and social factors were controlled including symptoms of alcohol and other drug use disorders, family environment, psychological distress, and symptoms of antisocial disorder. In contrast to findings in treatment-seeking samples, women with gambling problems did not report greater maltreatment than men with gambling problems. These results underscore the need for both increased prevention of childhood maltreatment and increased sensitivity towards trauma issues in gambling treatment programs for men and women.

  12. The problem of sampling families rather than populations: Relatedness among individuals in samples of juvenile brown trout Salmo trutta L

    DEFF Research Database (Denmark)

    Hansen, Michael Møller; Eg Nielsen, Einar; Mensberg, Karen-Lise Dons

    1997-01-01

    In species exhibiting a nonrandom distribution of closely related individuals, sampling of a few families may lead to biased estimates of allele frequencies in populations. This problem was studied in two brown trout populations, based on analysis of mtDNA and microsatellites. In both samples mt......DNA haplotype frequencies differed significantly between age classes, and in one sample 17 out of 18 individuals less than 1 year of age shared one particular mtDNA haplotype. Estimates of relatedness showed that these individuals most likely represented only three full-sib families. Older trout exhibiting...

  13. Faster Black-Box Algorithms Through Higher Arity Operators

    DEFF Research Database (Denmark)

    Doerr, Benjamin; Johannsen, Daniel; Kötzing, Timo

    2011-01-01

    We extend the work of Lehre and Witt (GECCO 2010) on the unbiased black-box model by considering higher arity variation operators. In particular, we show that already for binary operators the black-box complexity of LeadingOnes drops from (n2) for unary operators to O(n log n). For OneMax, the (n...

  14. Unit Stratified Sampling as a Tool for Approximation of Stochastic Optimization Problems

    Czech Academy of Sciences Publication Activity Database

    Šmíd, Martin

    2012-01-01

    Roč. 19, č. 30 (2012), s. 153-169 ISSN 1212-074X R&D Projects: GA ČR GAP402/11/0150; GA ČR GAP402/10/0956; GA ČR GA402/09/0965 Institutional research plan: CEZ:AV0Z10750506 Institutional support: RVO:67985556 Keywords : Stochastic programming * approximation * stratified sampling Subject RIV: BB - Applied Statistics, Operational Research http://library.utia.cas.cz/separaty/2013/E/smid-unit stratified sampling as a tool for approximation of stochastic optimization problems.pdf

  15. Robustness to non-normality of various tests for the one-sample location problem

    Directory of Open Access Journals (Sweden)

    Michelle K. McDougall

    2004-01-01

    Full Text Available This paper studies the effect of the normal distribution assumption on the power and size of the sign test, Wilcoxon's signed rank test and the t-test when used in one-sample location problems. Power functions for these tests under various skewness and kurtosis conditions are produced for several sample sizes from simulated data using the g-and-k distribution of MacGillivray and Cannon [5].

  16. Statistical surrogate model based sampling criterion for stochastic global optimization of problems with constraints

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Su Gil; Jang, Jun Yong; Kim, Ji Hoon; Lee, Tae Hee [Hanyang University, Seoul (Korea, Republic of); Lee, Min Uk [Romax Technology Ltd., Seoul (Korea, Republic of); Choi, Jong Su; Hong, Sup [Korea Research Institute of Ships and Ocean Engineering, Daejeon (Korea, Republic of)

    2015-04-15

    Sequential surrogate model-based global optimization algorithms, such as super-EGO, have been developed to increase the efficiency of commonly used global optimization technique as well as to ensure the accuracy of optimization. However, earlier studies have drawbacks because there are three phases in the optimization loop and empirical parameters. We propose a united sampling criterion to simplify the algorithm and to achieve the global optimum of problems with constraints without any empirical parameters. It is able to select the points located in a feasible region with high model uncertainty as well as the points along the boundary of constraint at the lowest objective value. The mean squared error determines which criterion is more dominant among the infill sampling criterion and boundary sampling criterion. Also, the method guarantees the accuracy of the surrogate model because the sample points are not located within extremely small regions like super-EGO. The performance of the proposed method, such as the solvability of a problem, convergence properties, and efficiency, are validated through nonlinear numerical examples with disconnected feasible regions.

  17. Update Strength in EDAs and ACO: How to Avoid Genetic Drift

    DEFF Research Database (Denmark)

    Sudholt, Dirk; Witt, Carsten

    2016-01-01

    , showing that the update strength should be limited to 1/K, ρ = O(1/(√n log n)). In fact, choosing 1/K, ρ ∼ 1/(√n log n) both algorithms efficiently optimize OneMax in expected time O (n log n). Our analyses provide new insights into the stochastic behavior of probabilistic model-building GAs and propose...

  18. Self-recognition of mental health problems in a rural Australian sample.

    Science.gov (United States)

    Handley, Tonelle E; Lewin, Terry J; Perkins, David; Kelly, Brian

    2018-04-19

    Although mental health literacy has increased in recent years, mental illness is often under-recognised. There has been little research conducted on mental illness in rural areas; however, this can be most prominent in rural areas due to factors such as greater stigma and stoicism. The aim of this study is to create a profile of those who are most and least likely to self-identify mental health problems among rural residents with moderate- to-high psychological distress. Secondary analysis of a longitudinal postal survey. Rural and remote New South Wales, Australia. Four-hundred-and-seventy-two community residents. Participants completed the K10 Psychological Distress Scale, as well as the question 'In the past 12 months have you experienced any mental health problems?' The characteristics of those who reported moderate/high distress scores were explored by comparing those who did and did not experience mental health problems recently. Of the 472 participants, 319 (68%) with moderate/high distress reported a mental health problem. Reporting a mental health problem was higher among those with recent adverse life events or who perceived more stress from life events while lower among those who attributed their symptoms to a physical cause. Among a rural sample with moderate/high distress, one-third did not report a mental health problem. Results suggest a threshold effect, whereby mental health problems are more likely to be acknowledged in the context of additional life events. Ongoing public health campaigns are necessary to ensure that symptoms of mental illness are recognised in the multiple forms that they take. © 2018 National Rural Health Alliance Ltd.

  19. Non-erotic thoughts, attentional focus, and sexual problems in a community sample.

    Science.gov (United States)

    Nelson, Andrea L; Purdon, Christine

    2011-04-01

    According to Barlow's model of sexual dysfunction, anxiety in sexual situations leads to attentional focus on sexual performance at the expense of erotic cues, which compromises sexual arousal. This negative experience will enhance anxiety in future sexual situations, and non-erotic thoughts (NETs) relevant to performance will receive attentional priority. Previous research with student samples (Purdon & Holdaway, 2006; Purdon & Watson, 2010) has found that people experience many types of NETs in addition to performance-relevant thoughts, and that, consistent with Barlow's model, the frequency of and anxiety evoked by these thoughts is positively associated with sexual problems. Extending this previous work, the current study found that, in a community sample of women (N = 81) and men (N = 72) in long-term relationships, women were more likely to report body image concerns and external consequences of the sexual activity, while men were more likely to report performance-related concerns. Equally likely among men and women were thoughts about emotional consequences of the sexual activity. Regardless of thought content, experiencing more frequent NETs was associated with more sexual problems in both women and men. Moreover, as per Barlow's model, greater negative affect in anticipation of and during sexual activity predicted greater frequency of NETs and greater anxiety in response to NETs was associated with greater difficulty dismissing the thoughts. However, greater difficulty in refocusing on erotic thoughts during sexual activity uniquely predicted more sexual problems above the frequency and dismissability of NETs. Together, these data support the cognitive interference mechanism implicated by Barlow's causal model of sexual dysfunction and have implications for the treatment of sexual problems.

  20. Recent bibliography on analytical and sampling problems of a PWR primary coolant Suppl. 4

    International Nuclear Information System (INIS)

    Illy, H.

    1986-09-01

    The 4th supplement of a bibliographical series comprising the analytical and sampling problems of the primary coolant of PWR type reactors covers the literature from 1985 up to July 1986 (220 items). References are listed according to the following topics: boric acid; chloride, chlorine; general; hydrogen isotopes; iodine; iodide; noble gases; oxygen; other elements; radiation monitoring; reactor safety; sampling; water chemistry. (V.N.)

  1. Sample problems for the novice user of the AMPX-II system

    International Nuclear Information System (INIS)

    Ford, W.E. III; Roussin, R.W.; Petrie, L.M.; Diggs, B.R.; Comolander, H.E.

    1979-01-01

    Contents of the IBM version of the APMX system distributed by the Radiation Shielding Information Center (APMX-II) are described. Sample problems which demonstrate the procedure for implementing AMPX-II modules to generate point cross sections; generate multigroup neutron, photon production, and photon interaction cross sections for various transport codes; collapse multigroup cross sections; check, edit, and punch multigroup cross sections; and execute a one-dimensional discrete ordinates transport calculation are detailed. 25 figures, 9 tables

  2. A direct sampling method to an inverse medium scattering problem

    KAUST Repository

    Ito, Kazufumi

    2012-01-10

    In this work we present a novel sampling method for time harmonic inverse medium scattering problems. It provides a simple tool to directly estimate the shape of the unknown scatterers (inhomogeneous media), and it is applicable even when the measured data are only available for one or two incident directions. A mathematical derivation is provided for its validation. Two- and three-dimensional numerical simulations are presented, which show that the method is accurate even with a few sets of scattered field data, computationally efficient, and very robust with respect to noises in the data. © 2012 IOP Publishing Ltd.

  3. Local entropy as a measure for sampling solutions in constraint satisfaction problems

    International Nuclear Information System (INIS)

    Baldassi, Carlo; Ingrosso, Alessandro; Lucibello, Carlo; Saglietti, Luca; Zecchina, Riccardo

    2016-01-01

    We introduce a novel entropy-driven Monte Carlo (EdMC) strategy to efficiently sample solutions of random constraint satisfaction problems (CSPs). First, we extend a recent result that, using a large-deviation analysis, shows that the geometry of the space of solutions of the binary perceptron learning problem (a prototypical CSP), contains regions of very high-density of solutions. Despite being sub-dominant, these regions can be found by optimizing a local entropy measure. Building on these results, we construct a fast solver that relies exclusively on a local entropy estimate, and can be applied to general CSPs. We describe its performance not only for the perceptron learning problem but also for the random K-satisfiabilty problem (another prototypical CSP with a radically different structure), and show numerically that a simple zero-temperature Metropolis search in the smooth local entropy landscape can reach sub-dominant clusters of optimal solutions in a small number of steps, while standard Simulated Annealing either requires extremely long cooling procedures or just fails. We also discuss how the EdMC can heuristically be made even more efficient for the cases we studied. (paper: disordered systems, classical and quantum)

  4. Hybrid nested sampling algorithm for Bayesian model selection applied to inverse subsurface flow problems

    International Nuclear Information System (INIS)

    Elsheikh, Ahmed H.; Wheeler, Mary F.; Hoteit, Ibrahim

    2014-01-01

    A Hybrid Nested Sampling (HNS) algorithm is proposed for efficient Bayesian model calibration and prior model selection. The proposed algorithm combines, Nested Sampling (NS) algorithm, Hybrid Monte Carlo (HMC) sampling and gradient estimation using Stochastic Ensemble Method (SEM). NS is an efficient sampling algorithm that can be used for Bayesian calibration and estimating the Bayesian evidence for prior model selection. Nested sampling has the advantage of computational feasibility. Within the nested sampling algorithm, a constrained sampling step is performed. For this step, we utilize HMC to reduce the correlation between successive sampled states. HMC relies on the gradient of the logarithm of the posterior distribution, which we estimate using a stochastic ensemble method based on an ensemble of directional derivatives. SEM only requires forward model runs and the simulator is then used as a black box and no adjoint code is needed. The developed HNS algorithm is successfully applied for Bayesian calibration and prior model selection of several nonlinear subsurface flow problems

  5. Hybrid nested sampling algorithm for Bayesian model selection applied to inverse subsurface flow problems

    Energy Technology Data Exchange (ETDEWEB)

    Elsheikh, Ahmed H., E-mail: aelsheikh@ices.utexas.edu [Institute for Computational Engineering and Sciences (ICES), University of Texas at Austin, TX (United States); Institute of Petroleum Engineering, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Wheeler, Mary F. [Institute for Computational Engineering and Sciences (ICES), University of Texas at Austin, TX (United States); Hoteit, Ibrahim [Department of Earth Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal (Saudi Arabia)

    2014-02-01

    A Hybrid Nested Sampling (HNS) algorithm is proposed for efficient Bayesian model calibration and prior model selection. The proposed algorithm combines, Nested Sampling (NS) algorithm, Hybrid Monte Carlo (HMC) sampling and gradient estimation using Stochastic Ensemble Method (SEM). NS is an efficient sampling algorithm that can be used for Bayesian calibration and estimating the Bayesian evidence for prior model selection. Nested sampling has the advantage of computational feasibility. Within the nested sampling algorithm, a constrained sampling step is performed. For this step, we utilize HMC to reduce the correlation between successive sampled states. HMC relies on the gradient of the logarithm of the posterior distribution, which we estimate using a stochastic ensemble method based on an ensemble of directional derivatives. SEM only requires forward model runs and the simulator is then used as a black box and no adjoint code is needed. The developed HNS algorithm is successfully applied for Bayesian calibration and prior model selection of several nonlinear subsurface flow problems.

  6. Hybrid nested sampling algorithm for Bayesian model selection applied to inverse subsurface flow problems

    KAUST Repository

    Elsheikh, Ahmed H.

    2014-02-01

    A Hybrid Nested Sampling (HNS) algorithm is proposed for efficient Bayesian model calibration and prior model selection. The proposed algorithm combines, Nested Sampling (NS) algorithm, Hybrid Monte Carlo (HMC) sampling and gradient estimation using Stochastic Ensemble Method (SEM). NS is an efficient sampling algorithm that can be used for Bayesian calibration and estimating the Bayesian evidence for prior model selection. Nested sampling has the advantage of computational feasibility. Within the nested sampling algorithm, a constrained sampling step is performed. For this step, we utilize HMC to reduce the correlation between successive sampled states. HMC relies on the gradient of the logarithm of the posterior distribution, which we estimate using a stochastic ensemble method based on an ensemble of directional derivatives. SEM only requires forward model runs and the simulator is then used as a black box and no adjoint code is needed. The developed HNS algorithm is successfully applied for Bayesian calibration and prior model selection of several nonlinear subsurface flow problems. © 2013 Elsevier Inc.

  7. Sustained impact of inattention and hyperactivity-impulsivity on peer problems: mediating roles of prosocial skills and conduct problems in a community sample of children.

    Science.gov (United States)

    Andrade, Brendan F; Tannock, Rosemary

    2014-06-01

    This prospective 2-year longitudinal study tested whether inattentive and hyperactive/impulsive symptom dimensions predicted future peer problems, when accounting for concurrent conduct problems and prosocial skills. A community sample of 492 children (49 % female) who ranged in age from 6 to 10 years (M = 8.6, SD = .93) was recruited. Teacher reports of children's inattention, and hyperactivity/impulsivity symptoms, conduct problems, prosocial skills and peer problems were collected in two consecutive school years. Elevated inattention and hyperactivity/impulsivity in Year-1 predicted greater peer problems in Year-2. Conduct problems in the first and second years of the study were associated with more peer problems, and explained a portion of the relationship between inattention and hyperactivity/impulsivity with peer problems. However, prosocial skills were associated with fewer peer problems in children with elevated inattention and hyperactivity/impulsivity. Inattention and hyperactivity/impulsivity have negative effects on children's peer functioning after 1-year, but concurrent conduct problems and prosocial skills have important and opposing impacts on these associations.

  8. Problematic Technology Use in a clinical sample of children and adolescents. Personality and behavioral problems associated.

    Science.gov (United States)

    Alonso, Cristina; Romero, Estrella

    2017-03-01

    In parallel to the rapid growth of access to new technologies (NT) there has been an increase in the problematic use of the same, especially among children and adolescents. Although research in this field is increasing, the studies have mainly been developed in the community, and the characteristics associated with the problematic use of NT are unknown in samples that require clinical care. Therefore, the aim of this study is to analyze the relationship between problematic use of video games (UPV) and Internet (UPI) and personality traits and behavior problems in a clinical sample of children and adolescents. The sample consists of 88 patients who were examined in the clinical psychology consultation in the Mental Health Unit for Children and Adolescents of the University Hospital of Santiago de Compostela. Data were obtained from self-reports and rating scales filled out by parents. 31.8% of the participants present UPI and 18.2%, UPV. The children and adolescents with UPNT have lower levels of Openness to experience, Conscientiousness and Agreeableness and higher levels of Emotional instability, global Impulsivity and Externalizing behavior problems, as well as Attention and Thought problems. UPNT is a problem that emerges as an important issue in clinical care for children and adolescents, so its study in child and youth care units is needed. Understanding the psychopathological profile of children and adolescents with UPNT will allow for the development of differential and more specific interventions.

  9. The direct effects of inattention and hyperactivity/impulsivity on peer problems and mediating roles of prosocial and conduct problem behaviors in a community sample of children.

    Science.gov (United States)

    Andrade, Brendan F; Tannock, Rosemary

    2013-11-01

    This study tested whether children's symptoms of inattention and hyperactivity/impulsivity were associated with peer problems and whether these associations were mediated by conduct problems and prosocial behaviors. A community sample of 500 children, including 245 boys and 255 girls, who ranged in age from 6 to 9 years (M = 7.6, SD = 0.91) were recruited. Teachers' report of children's inattention, hyperactivity/impulsivity, conduct problems, prosocial behaviors, and peer problems was collected. Symptoms of inattention and hyperactivity/impulsivity were significantly positively associated with peer problems. Conduct problems were associated with more peer problems and prosocial behaviors with less peer problems. Conduct problems and prosocial behaviors partially mediated the association between hyperactivity/impulsivity and peer problems and fully mediated the inattention-peer problems association. Findings show that prosocial behaviors and conduct problems are important variables that account for some of the negative impact of symptoms of inattention and hyperactivity/impulsivity on peer functioning.

  10. Recent bibliography on analytical and sampling problems of a PWR primary coolant Suppl. 3

    International Nuclear Information System (INIS)

    Illy, H.

    1985-03-01

    The present supplement to the bibliography on analytical and sampling problems of PWR primary coolant covers the literature published in 1984 and includes some references overlooked in the previous volumes dealing with the publications of the last 10 years. References are devided into topics characterized by the following headlines: boric acid; chloride; chlorine; carbon dioxide; general; gas analysis; hydrogen isotopes; iodine; iodide; nitrogen; noble gases and radium; ammonia; ammonium; oxygen; other elements; radiation monitoring; reactor safety; sampling; water chemistry. Under a given subject bibliographical information is listed in alphabetical order of the authors. (V.N.)

  11. Polygenic scores predict alcohol problems in an independent sample and show moderation by the environment.

    Science.gov (United States)

    Salvatore, Jessica E; Aliev, Fazil; Edwards, Alexis C; Evans, David M; Macleod, John; Hickman, Matthew; Lewis, Glyn; Kendler, Kenneth S; Loukola, Anu; Korhonen, Tellervo; Latvala, Antti; Rose, Richard J; Kaprio, Jaakko; Dick, Danielle M

    2014-04-10

    Alcohol problems represent a classic example of a complex behavioral outcome that is likely influenced by many genes of small effect. A polygenic approach, which examines aggregate measured genetic effects, can have predictive power in cases where individual genes or genetic variants do not. In the current study, we first tested whether polygenic risk for alcohol problems-derived from genome-wide association estimates of an alcohol problems factor score from the age 18 assessment of the Avon Longitudinal Study of Parents and Children (ALSPAC; n = 4304 individuals of European descent; 57% female)-predicted alcohol problems earlier in development (age 14) in an independent sample (FinnTwin12; n = 1162; 53% female). We then tested whether environmental factors (parental knowledge and peer deviance) moderated polygenic risk to predict alcohol problems in the FinnTwin12 sample. We found evidence for both polygenic association and for additive polygene-environment interaction. Higher polygenic scores predicted a greater number of alcohol problems (range of Pearson partial correlations 0.07-0.08, all p-values ≤ 0.01). Moreover, genetic influences were significantly more pronounced under conditions of low parental knowledge or high peer deviance (unstandardized regression coefficients (b), p-values (p), and percent of variance (R2) accounted for by interaction terms: b = 1.54, p = 0.02, R2 = 0.33%; b = 0.94, p = 0.04, R2 = 0.30%, respectively). Supplementary set-based analyses indicated that the individual top single nucleotide polymorphisms (SNPs) contributing to the polygenic scores were not individually enriched for gene-environment interaction. Although the magnitude of the observed effects are small, this study illustrates the usefulness of polygenic approaches for understanding the pathways by which measured genetic predispositions come together with environmental factors to predict complex behavioral outcomes.

  12. Condom-related problems among a racially diverse sample of young men who have sex with men.

    Science.gov (United States)

    Du Bois, Steve N; Emerson, Erin; Mustanski, Brian

    2011-10-01

    We described frequencies of condom-related problems in a racially diverse sample of young men who have sex with men (YMSM), and tested these condom-related problems as an explanation for racial disparities in HIV rates among YMSM. Participants were 119 YMSM from a longitudinal study of sexual minority health behaviors. Almost all participants (95.4%) experienced at least one condom error. On average, African American and non-African American YMSM experienced the same number of recent condom-related problems. Therefore, differences in condom-related problems are unlikely to explain racial disparities in HIV rates among YMSM. When serving YMSM, providers should both promote condom use and explain steps to correct condom use.

  13. Food insecurity and mental health problems among a community sample of young adults.

    Science.gov (United States)

    Pryor, Laura; Lioret, Sandrine; van der Waerden, Judith; Fombonne, Éric; Falissard, Bruno; Melchior, Maria

    2016-08-01

    Food insecurity has been found to be related to anxiety and depression; however, the association with other psychiatric disorders, particularly among young adults, is not well known. We examined whether food insecurity is independently associated with four common mental health problems among a community sample of young adults in France. Data are from the TEMPO longitudinal cohort study. In 1991, participants' parents provided information on health and family socioeconomic characteristics. In 2011, participants' (18-35 years) reported food insecurity, mental health symptoms, and socioeconomic conditions (n = 1214). Mental health problems ascertained included major depressive episode, suicidal ideation, attention deficit and hyperactivity disorder, and substance abuse and/or dependence (nicotine, alcohol and cannabis). Cross-sectional associations between food insecurity and mental health problems were tested using modified Poisson regressions, weighted by inverse probability weights (IPW) of exposure. This makes food insecure and not food insecure participants comparable on all characteristics including socioeconomic factors and past mental health problems. 8.5 % of young adults were food insecure. In IPW-controlled analyses, food insecurity was associated with increased levels of depression (RR = 2.01, 95 % CI 1.01-4.02), suicidal ideation (RR = 3.23, 95 % CI 1.55-6.75) and substance use problems (RR = 1.68, 95 % CI 1.15-2.46). Food insecurity co-occurs with depression, suicidal ideation and substance use problems in young adulthood. Our findings suggest that reductions in food insecurity during this important life period may help prevent mental health problems. Policies aiming to alleviate food insecurity should also address individuals' psychiatric problems, to prevent a lifelong vicious circle of poor mental health and low socioeconomic attainment.

  14. Efficient Monte Carlo sampling of inverse problems using a neural network-based forward—applied to GPR crosshole traveltime inversion

    Science.gov (United States)

    Hansen, T. M.; Cordua, K. S.

    2017-12-01

    Probabilistically formulated inverse problems can be solved using Monte Carlo-based sampling methods. In principle, both advanced prior information, based on for example, complex geostatistical models and non-linear forward models can be considered using such methods. However, Monte Carlo methods may be associated with huge computational costs that, in practice, limit their application. This is not least due to the computational requirements related to solving the forward problem, where the physical forward response of some earth model has to be evaluated. Here, it is suggested to replace a numerical complex evaluation of the forward problem, with a trained neural network that can be evaluated very fast. This will introduce a modeling error that is quantified probabilistically such that it can be accounted for during inversion. This allows a very fast and efficient Monte Carlo sampling of the solution to an inverse problem. We demonstrate the methodology for first arrival traveltime inversion of crosshole ground penetrating radar data. An accurate forward model, based on 2-D full-waveform modeling followed by automatic traveltime picking, is replaced by a fast neural network. This provides a sampling algorithm three orders of magnitude faster than using the accurate and computationally expensive forward model, and also considerably faster and more accurate (i.e. with better resolution), than commonly used approximate forward models. The methodology has the potential to dramatically change the complexity of non-linear and non-Gaussian inverse problems that have to be solved using Monte Carlo sampling techniques.

  15. SIPPI: A Matlab toolbox for sampling the solution to inverse problems with complex prior information

    DEFF Research Database (Denmark)

    Hansen, Thomas Mejer; Cordua, Knud Skou; Looms, Majken Caroline

    2013-01-01

    We present an application of the SIPPI Matlab toolbox, to obtain a sample from the a posteriori probability density function for the classical tomographic inversion problem. We consider a number of different forward models, linear and non-linear, such as ray based forward models that rely...

  16. Polygenic Scores Predict Alcohol Problems in an Independent Sample and Show Moderation by the Environment

    Directory of Open Access Journals (Sweden)

    Jessica E. Salvatore

    2014-04-01

    Full Text Available Alcohol problems represent a classic example of a complex behavioral outcome that is likely influenced by many genes of small effect. A polygenic approach, which examines aggregate measured genetic effects, can have predictive power in cases where individual genes or genetic variants do not. In the current study, we first tested whether polygenic risk for alcohol problems—derived from genome-wide association estimates of an alcohol problems factor score from the age 18 assessment of the Avon Longitudinal Study of Parents and Children (ALSPAC; n = 4304 individuals of European descent; 57% female—predicted alcohol problems earlier in development (age 14 in an independent sample (FinnTwin12; n = 1162; 53% female. We then tested whether environmental factors (parental knowledge and peer deviance moderated polygenic risk to predict alcohol problems in the FinnTwin12 sample. We found evidence for both polygenic association and for additive polygene-environment interaction. Higher polygenic scores predicted a greater number of alcohol problems (range of Pearson partial correlations 0.07–0.08, all p-values ≤ 0.01. Moreover, genetic influences were significantly more pronounced under conditions of low parental knowledge or high peer deviance (unstandardized regression coefficients (b, p-values (p, and percent of variance (R2 accounted for by interaction terms: b = 1.54, p = 0.02, R2 = 0.33%; b = 0.94, p = 0.04, R2 = 0.30%, respectively. Supplementary set-based analyses indicated that the individual top single nucleotide polymorphisms (SNPs contributing to the polygenic scores were not individually enriched for gene-environment interaction. Although the magnitude of the observed effects are small, this study illustrates the usefulness of polygenic approaches for understanding the pathways by which measured genetic predispositions come together with environmental factors to predict complex behavioral outcomes.

  17. The role of self-esteem in the development of psychiatric problems: a three-year prospective study in a clinical sample of adolescents.

    Science.gov (United States)

    Henriksen, Ingvild Oxås; Ranøyen, Ingunn; Indredavik, Marit Sæbø; Stenseng, Frode

    2017-01-01

    Self-esteem is fundamentally linked to mental health, but its' role in trajectories of psychiatric problems is unclear. In particular, few studies have addressed the role of self-esteem in the development of attention problems. Hence, we examined the role of global self-esteem in the development of symptoms of anxiety/depression and attention problems, simultaneously, in a clinical sample of adolescents while accounting for gender, therapy, and medication. Longitudinal data were obtained from a sample of 201 adolescents-aged 13-18-referred to the Department of Child and Adolescent Psychiatry in Trondheim, Norway. In the baseline study, self-esteem, and symptoms of anxiety/depression and attention problems were measured by means of self-report. Participants were reassessed 3 years later, with a participation rate of 77% in the clinical sample. Analyses showed that high self-esteem at baseline predicted fewer symptoms of both anxiety/depression and attention problems 3 years later after controlling for prior symptom levels, gender, therapy (or not), and medication. Results highlight the relevance of global self-esteem in the clinical practice, not only with regard to emotional problems, but also to attention problems. Implications for clinicians, parents, and others are discussed.

  18. Recent bibliography on analytical and sampling problems of a PWR primary coolant Pt. 1

    International Nuclear Information System (INIS)

    Illy, H.

    1981-12-01

    The first bibliography on analytical and sampling problems of a PWR primary coolant (KFKI Report-1980-48) was published in 1980 and it covered the literature published in the previous 8-10 years. The present supplement reviews the subsequent literature up till December 1981. It also includes some references overlooked in the first volume. The serial numbers are continued from the first bibliography. (author)

  19. The association of ADHD and depression: Mediation by peer problems and parent-child difficulties in two complementary samples

    Science.gov (United States)

    Humphreys, Kathryn L.; Katz, Shaina J.; Lee, Steve S.; Hammen, Constance L.; Brennan, Patricia A.; Najman, Jake M.

    2013-01-01

    Children with attention-deficit/hyperactivity disorder (ADHD) are at increased risk for the development of depression, with evidence that peer and academic difficulties mediate predictions of later depression from ADHD. The present study hypothesized that parent-child relationship difficulties may be an additional potential mediator of this association. Academic, peer, and parent-child functioning were tested as mediators of the association of attention problems and depression in two distinctly different, yet complementary samples. Study 1 was a cross-sectional sample of 230 5–10 year-old children with and without ADHD. Study 2 was a prospective longitudinal sample of 472 youth followed prospectively from birth to age 20 at risk for depression. Despite differences in age, measures, and designs, both studies implicated peer and parent-child problems as unique mediators of depressive symptoms, although academic difficulties did not uniquely mediate the ADHD-depression association. Further, inattention symptoms, but not hyperactivity, predicted depressive symptoms via the disruption of interpersonal functioning. The inclusion of oppositional defiant disorder into models impacted results, and supported its independent role in parent-child problems. Implications include support for interventions that target interpersonal competence, which may effectively reduce the risk of depression among children with ADHD. PMID:24016021

  20. Eating Problems and Their Risk Factors: A 7-Year Longitudinal Study of a Population Sample of Norwegian Adolescent Girls

    Science.gov (United States)

    Kansi, Juliska; Wichstrom, Lars; Bergman, Lars R.

    2005-01-01

    The longitudinal stability of eating problems and their relationships to risk factors were investigated in a representative population sample of 623 Norwegian girls aged 13-14 followed over 7 years (3 time points). Three eating problem symptoms were measured: Restriction, Bulimia-food preoccupation, and Diet, all taken from the 12-item Eating…

  1. Graphics for the multivariate two-sample problem

    International Nuclear Information System (INIS)

    Friedman, J.H.; Rafsky, L.C.

    1981-01-01

    Some graphical methods for comparing multivariate samples are presented. These methods are based on minimal spanning tree techniques developed for multivariate two-sample tests. The utility of these methods is illustrated through examples using both real and artificial data

  2. (1+1) EA on Generalized Dynamic OneMax

    DEFF Research Database (Denmark)

    Kötzing, Timo; Lissovoi, Andrei; Witt, Carsten

    2015-01-01

    . We get tight bounds both for the case of bit strings, as well as for the case of more than two values per position. Surprisingly, in the latter setting, the expected quality of the search point maintained by the (1+1) EA does not depend on the number of values per dimension....... using the modern tool of drift analysis. We extend these results to search spaces which allow for more than two values per dimension. Furthermore, we make an anytime analysis as suggested by Jansen and Zarges (2014), analyzing how closely the (1+1) EA can track the dynamically moving optimum over time...

  3. Sample problem manual for benchmarking of cask analysis codes

    International Nuclear Information System (INIS)

    Glass, R.E.

    1988-02-01

    A series of problems have been defined to evaluate structural and thermal codes. These problems were designed to simulate the hypothetical accident conditions given in Title 10 of the Code of Federal Regulation, Part 71 (10CFR71) while retaining simple geometries. This produced a problem set that exercises the ability of the codes to model pertinent physical phenomena without requiring extensive use of computer resources. The solutions that are presented are consensus solutions based on computer analyses done by both national laboratories and industry in the United States, United Kingdom, France, Italy, Sweden, and Japan. The intent of this manual is to provide code users with a set of standard structural and thermal problems and solutions which can be used to evaluate individual codes. 19 refs., 19 figs., 14 tabs

  4. Does parent-child agreement vary based on presenting problems? Results from a UK clinical sample.

    Science.gov (United States)

    Cleridou, Kalia; Patalay, Praveetha; Martin, Peter

    2017-01-01

    Discrepancies are often found between child and parent reports of child psychopathology, nevertheless the role of the child's presenting difficulties in relation to these is underexplored. This study investigates whether parent-child agreement on the conduct and emotional scales of the Strengths and Difficulties Questionnaire (SDQ) varied as a result of certain child characteristics, including the child's presenting problems to clinical services, age and gender. The UK-based sample consisted of 16,754 clinical records of children aged 11-17, the majority of which were female (57%) and White (76%). The dataset was provided by the Child Outcomes Research Consortium , which collects outcome measures from child services across the UK. Clinicians reported the child's presenting difficulties, and parents and children completed the SDQ. Using correlation analysis, the main findings indicated that agreement varied as a result of the child's difficulties for reports of conduct problems, and this seemed to be related to the presence or absence of externalising difficulties in the child's presentation. This was not the case for reports of emotional difficulties. In addition, agreement was higher when reporting problems not consistent with the child's presentation; for instance, agreement on conduct problems was greater for children presenting with internalising problems. Lastly, the children's age and gender did not seem to have an impact on agreement. These findings demonstrate that certain child presenting difficulties, and in particular conduct problems, may be related to informant agreement and need to be considered in clinical practice and research. Trial Registration This study was observational and as such did not require trial registration.

  5. Gambling Type, Substance Abuse, Health and Psychosocial Correlates of Male and Female Problem Gamblers in a Nationally Representative French Sample.

    Science.gov (United States)

    Bonnaire, C; Kovess-Masfety, V; Guignard, R; Richard, J B; du Roscoät, E; Beck, F

    2017-06-01

    Many studies carried out on treatment-seeking problem gamblers (PG) have reported high levels of comorbid substance use disorders, and mental and physical health problems. Nevertheless, general population studies are still sparse, most of them have been carried out in the United States or Canada, and gender differences have not always been considered. Thus, the aim of this study was to describe the type of games, and psychological and physical correlates in male and female PG in a nationally representative French sample. The total sample studied involved 25,647 subjects aged 15-85 years, including 333 PG and 25,314 non-problem gamblers (NPG). Data were extracted from a large survey of a representative sample of the French general population. They were evaluated for sociodemographic variables, gambling behavior, type of gambling activity, substance use, psychological distress, body mass index, chronic disease, and lack of sleep. Overall, there were significant differences between PG and NPG in gender, age, education, employment and marital status, substance use disorders (alcohol, tobacco, cannabis, cocaine and heroin), psychological distress, obesity, lack of sleep and type of gambling activity. Although male and female PG had different profiles, the gambling type, especially strategic games, appeared as an important variable in the relationship between gender and problem gambling. This research underlines the importance of considering gender differences and gambling type in the study of gambling disorders. Identifying specific factors in the relationship between gender, gambling type and gambling problems may help improve clinical interventions and health promotion strategies.

  6. The link between ethnicity, social disadvantage and mental health problems in a school-based multiethnic sample of children in the Netherlands

    NARCIS (Netherlands)

    Adriaanse, M.; Veling, W.; Doreleijers, T.A.H.; van Domburgh, L.

    2014-01-01

    To investigate to what extent differences in prevalence and types of mental health problems between ethnic minority and majority youth can be explained by social disadvantage. Mental health problems were assessed in a sample of 1,278 schoolchildren (55 % Dutch, 32 % Moroccan and 13 % Turkish; mean

  7. The link between ethnicity, social disadvantage and mental health problems in a school-based multiethnic sample of children in the Netherlands

    NARCIS (Netherlands)

    Adriaanse, Marcia; Veling, Wim; Doreleijers, Theo; van Domburgh, Lieke

    To investigate to what extent differences in prevalence and types of mental health problems between ethnic minority and majority youth can be explained by social disadvantage. Mental health problems were assessed in a sample of 1,278 schoolchildren (55 % Dutch, 32 % Moroccan and 13 % Turkish; mean

  8. Weighted piecewise LDA for solving the small sample size problem in face verification.

    Science.gov (United States)

    Kyperountas, Marios; Tefas, Anastasios; Pitas, Ioannis

    2007-03-01

    A novel algorithm that can be used to boost the performance of face-verification methods that utilize Fisher's criterion is presented and evaluated. The algorithm is applied to similarity, or matching error, data and provides a general solution for overcoming the "small sample size" (SSS) problem, where the lack of sufficient training samples causes improper estimation of a linear separation hyperplane between the classes. Two independent phases constitute the proposed method. Initially, a set of weighted piecewise discriminant hyperplanes are used in order to provide a more accurate discriminant decision than the one produced by the traditional linear discriminant analysis (LDA) methodology. The expected classification ability of this method is investigated throughout a series of simulations. The second phase defines proper combinations for person-specific similarity scores and describes an outlier removal process that further enhances the classification ability. The proposed technique has been tested on the M2VTS and XM2VTS frontal face databases. Experimental results indicate that the proposed framework greatly improves the face-verification performance.

  9. Superposition Enhanced Nested Sampling

    Directory of Open Access Journals (Sweden)

    Stefano Martiniani

    2014-08-01

    Full Text Available The theoretical analysis of many problems in physics, astronomy, and applied mathematics requires an efficient numerical exploration of multimodal parameter spaces that exhibit broken ergodicity. Monte Carlo methods are widely used to deal with these classes of problems, but such simulations suffer from a ubiquitous sampling problem: The probability of sampling a particular state is proportional to its entropic weight. Devising an algorithm capable of sampling efficiently the full phase space is a long-standing problem. Here, we report a new hybrid method for the exploration of multimodal parameter spaces exhibiting broken ergodicity. Superposition enhanced nested sampling combines the strengths of global optimization with the unbiased or athermal sampling of nested sampling, greatly enhancing its efficiency with no additional parameters. We report extensive tests of this new approach for atomic clusters that are known to have energy landscapes for which conventional sampling schemes suffer from broken ergodicity. We also introduce a novel parallelization algorithm for nested sampling.

  10. Choosing a suitable sample size in descriptive sampling

    International Nuclear Information System (INIS)

    Lee, Yong Kyun; Choi, Dong Hoon; Cha, Kyung Joon

    2010-01-01

    Descriptive sampling (DS) is an alternative to crude Monte Carlo sampling (CMCS) in finding solutions to structural reliability problems. It is known to be an effective sampling method in approximating the distribution of a random variable because it uses the deterministic selection of sample values and their random permutation,. However, because this method is difficult to apply to complex simulations, the sample size is occasionally determined without thorough consideration. Input sample variability may cause the sample size to change between runs, leading to poor simulation results. This paper proposes a numerical method for choosing a suitable sample size for use in DS. Using this method, one can estimate a more accurate probability of failure in a reliability problem while running a minimal number of simulations. The method is then applied to several examples and compared with CMCS and conventional DS to validate its usefulness and efficiency

  11. Gender and Direction of Effect of Alcohol Problems and Internalizing Symptoms in a Longitudinal Sample of College Students.

    Science.gov (United States)

    Homman, Lina E; Edwards, Alexis C; Cho, Seung Bin; Dick, Danielle M; Kendler, Kenneth S

    2017-03-21

    Alcohol problems and internalizing symptoms are consistently found to be associated but how they relate to each other is unclear. The present study aimed to address limitations in the literature of comorbidity of alcohol problems and internalizing symptoms by investigating the direction of effect between the phenotypes and possible gender differences in college students. We utilized data from a large longitudinal study of college students from the United States (N = 2607). Three waves of questionnaire-based data were collected over the first two years of college (in 2011-2013). Cross-lagged models were applied to examine the possible direction of effect of internalizing symptoms and alcohol problems. Possible effects of gender were investigated using multigroup modeling. There were significant correlations between alcohol problems and internalizing symptoms. A direction of effect was found between alcohol problems and internalizing symptoms but differed between genders. A unidirectional relationship varying with age was identified for males where alcohol problems initially predicted internalizing symptoms followed by internalizing symptoms predicting alcohol problems. For females, a unidirectional relationship existed wherein alcohol problems predicted internalizing symptoms. Conclusions/Importance: We conclude that the relationship between alcohol problems and internalizing symptoms is complex and differ between genders. In males, both phenotypes are predictive of each other, while in females the relationship is driven by alcohol problems. Importantly, our study examines a population-based sample, revealing that the observed relationships between alcohol problems and internalizing symptoms are not limited to individuals with clinically diagnosed mental health or substance use problems.

  12. A separation theorem for the stochastic sampled-data LQG problem. [control of continuous linear plant disturbed by white noise

    Science.gov (United States)

    Halyo, N.; Caglayan, A. K.

    1976-01-01

    This paper considers the control of a continuous linear plant disturbed by white plant noise when the control is constrained to be a piecewise constant function of time; i.e. a stochastic sampled-data system. The cost function is the integral of quadratic error terms in the state and control, thus penalizing errors at every instant of time while the plant noise disturbs the system continuously. The problem is solved by reducing the constrained continuous problem to an unconstrained discrete one. It is shown that the separation principle for estimation and control still holds for this problem when the plant disturbance and measurement noise are Gaussian.

  13. Near-optimal alternative generation using modified hit-and-run sampling for non-linear, non-convex problems

    Science.gov (United States)

    Rosenberg, D. E.; Alafifi, A.

    2016-12-01

    Water resources systems analysis often focuses on finding optimal solutions. Yet an optimal solution is optimal only for the modelled issues and managers often seek near-optimal alternatives that address un-modelled objectives, preferences, limits, uncertainties, and other issues. Early on, Modelling to Generate Alternatives (MGA) formalized near-optimal as the region comprising the original problem constraints plus a new constraint that allowed performance within a specified tolerance of the optimal objective function value. MGA identified a few maximally-different alternatives from the near-optimal region. Subsequent work applied Markov Chain Monte Carlo (MCMC) sampling to generate a larger number of alternatives that span the near-optimal region of linear problems or select portions for non-linear problems. We extend the MCMC Hit-And-Run method to generate alternatives that span the full extent of the near-optimal region for non-linear, non-convex problems. First, start at a feasible hit point within the near-optimal region, then run a random distance in a random direction to a new hit point. Next, repeat until generating the desired number of alternatives. The key step at each iterate is to run a random distance along the line in the specified direction to a new hit point. If linear equity constraints exist, we construct an orthogonal basis and use a null space transformation to confine hits and runs to a lower-dimensional space. Linear inequity constraints define the convex bounds on the line that runs through the current hit point in the specified direction. We then use slice sampling to identify a new hit point along the line within bounds defined by the non-linear inequity constraints. This technique is computationally efficient compared to prior near-optimal alternative generation techniques such MGA, MCMC Metropolis-Hastings, evolutionary, or firefly algorithms because search at each iteration is confined to the hit line, the algorithm can move in one

  14. Target problem (mis) matching: predictors and consequences of parent-youth agreement in a sample of anxious youth.

    Science.gov (United States)

    Hoffman, Lauren J; Chu, Brian C

    2015-04-01

    Parents and youth often report discrepant target problems upon seeking treatment for youth psychopathology, which can have important impact on therapy processes (e.g., dropout) and treatment outcomes, as entry-level attitudes have been found to be influential in ultimate use and benefit of treatment. The current study examined parent-youth agreement within an anxiety disordered sample by assessing demographic and diagnostic factors that may predict matching, as well as the impact of matching on attrition, treatment outcome, and parental satisfaction. Ninety-five youth with principal anxiety disorders received cognitive-behavioral treatment for anxiety at a university outpatient clinic. Youth and parents independently identified target problems during the pretreatment assessment. Target problems were coded into 25 qualitative categories representing diagnostic, symptom, and functional impairment domains, including diffuse anxiety, social anxiety, academic achievement, oppositional/behavior problems, sleep problems, suicidal ideation, and family functioning. The majority of parent-youth dyads (67.4%) agreed on at least one target problem. Although problems related to diffuse anxiety and social anxiety were reported most frequently, relatively low rates of agreement were found in these domains. Kappa values demonstrated higher levels of agreement for problems with specific fears, school attendance, and panic and lower levels of agreement for difficulties with worry, shame, and self-esteem. Further, youth diagnosed with comorbid externalizing disorders were less likely to agree with their parents on at least one target problem. No effects were found for gender, age, or number of diagnoses in predicting agreement. Target problem agreement did not significantly impact rates of attrition or diagnostic remission, but did predict some measures of parental satisfaction. Results suggest that disagreement on treatment goals exists even within a narrow treatment population and

  15. Exact sampling of the unobserved covariates in Bayesian spline models for measurement error problems.

    Science.gov (United States)

    Bhadra, Anindya; Carroll, Raymond J

    2016-07-01

    In truncated polynomial spline or B-spline models where the covariates are measured with error, a fully Bayesian approach to model fitting requires the covariates and model parameters to be sampled at every Markov chain Monte Carlo iteration. Sampling the unobserved covariates poses a major computational problem and usually Gibbs sampling is not possible. This forces the practitioner to use a Metropolis-Hastings step which might suffer from unacceptable performance due to poor mixing and might require careful tuning. In this article we show for the cases of truncated polynomial spline or B-spline models of degree equal to one, the complete conditional distribution of the covariates measured with error is available explicitly as a mixture of double-truncated normals, thereby enabling a Gibbs sampling scheme. We demonstrate via a simulation study that our technique performs favorably in terms of computational efficiency and statistical performance. Our results indicate up to 62 and 54 % increase in mean integrated squared error efficiency when compared to existing alternatives while using truncated polynomial splines and B-splines respectively. Furthermore, there is evidence that the gain in efficiency increases with the measurement error variance, indicating the proposed method is a particularly valuable tool for challenging applications that present high measurement error. We conclude with a demonstration on a nutritional epidemiology data set from the NIH-AARP study and by pointing out some possible extensions of the current work.

  16. Vibronic Boson Sampling: Generalized Gaussian Boson Sampling for Molecular Vibronic Spectra at Finite Temperature.

    Science.gov (United States)

    Huh, Joonsuk; Yung, Man-Hong

    2017-08-07

    Molecular vibroic spectroscopy, where the transitions involve non-trivial Bosonic correlation due to the Duschinsky Rotation, is strongly believed to be in a similar complexity class as Boson Sampling. At finite temperature, the problem is represented as a Boson Sampling experiment with correlated Gaussian input states. This molecular problem with temperature effect is intimately related to the various versions of Boson Sampling sharing the similar computational complexity. Here we provide a full description to this relation in the context of Gaussian Boson Sampling. We find a hierarchical structure, which illustrates the relationship among various Boson Sampling schemes. Specifically, we show that every instance of Gaussian Boson Sampling with an initial correlation can be simulated by an instance of Gaussian Boson Sampling without initial correlation, with only a polynomial overhead. Since every Gaussian state is associated with a thermal state, our result implies that every sampling problem in molecular vibronic transitions, at any temperature, can be simulated by Gaussian Boson Sampling associated with a product of vacuum modes. We refer such a generalized Gaussian Boson Sampling motivated by the molecular sampling problem as Vibronic Boson Sampling.

  17. Sample size methodology

    CERN Document Server

    Desu, M M

    2012-01-01

    One of the most important problems in designing an experiment or a survey is sample size determination and this book presents the currently available methodology. It includes both random sampling from standard probability distributions and from finite populations. Also discussed is sample size determination for estimating parameters in a Bayesian setting by considering the posterior distribution of the parameter and specifying the necessary requirements. The determination of the sample size is considered for ranking and selection problems as well as for the design of clinical trials. Appropria

  18. Calculation of sample problems related to two-phase flow blowdown transients in pressure relief piping of a PWR pressurizer

    International Nuclear Information System (INIS)

    Shin, Y.W.; Wiedermann, A.H.

    1984-02-01

    A method was published, based on the integral method of characteristics, by which the junction and boundary conditions needed in computation of a flow in a piping network can be accurately formulated. The method for the junction and boundary conditions formulation together with the two-step Lax-Wendroff scheme are used in a computer program; the program in turn, is used here in calculating sample problems related to the blowdown transient of a two-phase flow in the piping network downstream of a PWR pressurizer. Independent, nearly exact analytical solutions also are obtained for the sample problems. Comparison of the results obtained by the hybrid numerical technique with the analytical solutions showed generally good agreement. The good numerical accuracy shown by the results of our scheme suggest that the hybrid numerical technique is suitable for both benchmark and design calculations of PWR pressurizer blowdown transients

  19. Parent-Reported Psychological and Sleep Problems in a Preschool-Aged Community Sample: Prevalence of Sleep Problems in Children with and without Emotional/Behavioural Problems

    OpenAIRE

    Salater, Julie; Røhr, Marthe

    2010-01-01

    Objective : To examine (a) the prevalence of sleep problems among 4-year-olds in the general population, (b) the prevalence of sleep problems among children with emotional and/or behavioural problems, and (c) whether specific sleep problems are associated with particular emotional/behavioural problems. Method: Using The Preschool Age Psychiatric Assessment (PAPA) , data about sleep and emotional/behavioural problems was obtained from 727 parents of 4-year-olds, recruited for a large...

  20. Boat sampling

    International Nuclear Information System (INIS)

    Citanovic, M.; Bezlaj, H.

    1994-01-01

    This presentation describes essential boat sampling activities: on site boat sampling process optimization and qualification; boat sampling of base material (beltline region); boat sampling of weld material (weld No. 4); problems accompanied with weld crown varieties, RPV shell inner radius tolerance, local corrosion pitting and water clarity. The equipment used for boat sampling is described too. 7 pictures

  1. 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.

  2. Fast Markov chain Monte Carlo sampling for sparse Bayesian inference in high-dimensional inverse problems using L1-type priors

    International Nuclear Information System (INIS)

    Lucka, Felix

    2012-01-01

    Sparsity has become a key concept for solving of high-dimensional inverse problems using variational regularization techniques. Recently, using similar sparsity-constraints in the Bayesian framework for inverse problems by encoding them in the prior distribution has attracted attention. Important questions about the relation between regularization theory and Bayesian inference still need to be addressed when using sparsity promoting inversion. A practical obstacle for these examinations is the lack of fast posterior sampling algorithms for sparse, high-dimensional Bayesian inversion. Accessing the full range of Bayesian inference methods requires being able to draw samples from the posterior probability distribution in a fast and efficient way. This is usually done using Markov chain Monte Carlo (MCMC) sampling algorithms. In this paper, we develop and examine a new implementation of a single component Gibbs MCMC sampler for sparse priors relying on L1-norms. We demonstrate that the efficiency of our Gibbs sampler increases when the level of sparsity or the dimension of the unknowns is increased. This property is contrary to the properties of the most commonly applied Metropolis–Hastings (MH) sampling schemes. We demonstrate that the efficiency of MH schemes for L1-type priors dramatically decreases when the level of sparsity or the dimension of the unknowns is increased. Practically, Bayesian inversion for L1-type priors using MH samplers is not feasible at all. As this is commonly believed to be an intrinsic feature of MCMC sampling, the performance of our Gibbs sampler also challenges common beliefs about the applicability of sample based Bayesian inference. (paper)

  3. Communication Problems in Turner Syndrome: A Sample Survey.

    Science.gov (United States)

    Van Borsel, John; Dhooge, Inge; Verhoye, Kristof; Derde, Kristel; Curfs, Leopold

    1999-01-01

    A survey of 128 females (ages 2-58) with Turner syndrome found almost one quarter were receiving or had received treatment for stuttering, articulation problems, and/or delayed language development, with the latter two disorders being checked most frequently. Only 4 or the 68 individuals receiving growth hormone treatment reported voice changes.…

  4. Transactional effects among maternal depression, neighborhood deprivation, and child conduct problems from early childhood through adolescence: A tale of two low-income samples.

    Science.gov (United States)

    Shaw, Daniel S; Sitnick, Stephanie L; Reuben, Julia; Dishion, Thomas J; Wilson, Melvin N

    2016-08-01

    The current study sought to advance our understanding of transactional processes among maternal depression, neighborhood deprivation, and child conduct problems (CP) using two samples of low-income families assessed repeatedly from early childhood to early adolescence. After accounting for initial levels of negative parenting, independent and reciprocal effects between maternal depressive symptoms and child CP were evident across both samples, beginning in early childhood and continuing through middle childhood and adolescence. In addition, neighborhood effects were consistently found in both samples after children reached age 5, with earlier neighborhood effects on child CP and maternal depression found in the one exclusively urban sample of families with male children. The results confirm prior research on the independent contribution of maternal depression and child CP to the maintenance of both problem behaviors. The findings also have implications for designing preventative and clinical interventions to address child CP for families living in high-risk neighborhoods.

  5. Mental health problems and their association to violence and maltreatment in a nationally representative sample of Tanzanian secondary school students.

    Science.gov (United States)

    Nkuba, Mabula; Hermenau, Katharin; Goessmann, Katharina; Hecker, Tobias

    2018-04-12

    Little is known about the prevalence of mental health problems among adolescents in Sub-Saharan Africa. Research consistently determined violence and maltreatment to be important risk factors. In this study, we examined the prevalence of mental health problems among adolescents in Tanzania, as well as the association with exposure to violence and maltreatment. We administered a set of questionnaires (e.g., strength and difficulties questionnaire; conflict tactic scale) to a nationally representative sample of 700 Tanzanian secondary school children (52% girls; age 14.92 years, SD = 1.02) and 333 parents or primary caregivers (53% females; age 43.47 years, SD = 9.02). 41% of the students reported an elevated level of mental health problems (emotional problems 40%, peer problems 63%, conduct problems 45%, hyperactivity 17%) in the past 6 months. Concordantly, 31% of parents reported observing an elevated level of mental health problems in their children (emotional problems 37%, peer problems 54%, conduct problems 35%, hyperactivity 17%). After controlling for other risk factors, we found significant associations between physical violence by parents and adolescent's mental health problems reported by students (β = 0.15) and their parents (β = 0.33). Our findings suggest a high prevalence of mental health problems using screening tools among secondary school students in Tanzania as well as an association between physical violence by parents and adolescents' mental health problems. Our findings emphasize the need to inform the population at large about the potentially adverse consequences associated with violence against children and adolescents.

  6. Development, problem behavior, and quality of life in a population based sample of eight-year-old children with down syndrome

    NARCIS (Netherlands)

    Gameren-Oosterom, H.B.M. van; Fekkes, M.; Buitendijk, S.E.; Mohangoo, A.D.; Bruil, J.; Wouwe, J.P. van

    2011-01-01

    Objective: Children with Down syndrome (DS) have delayed psychomotor development. We investigated levels of development, problem behavior, and Health-Related Quality of Life (HRQoL) in a population sample of Dutch eight-year-old children with DS. Developmental outcomes were compared with normative

  7. Ensemble Sampling

    OpenAIRE

    Lu, Xiuyuan; Van Roy, Benjamin

    2017-01-01

    Thompson sampling has emerged as an effective heuristic for a broad range of online decision problems. In its basic form, the algorithm requires computing and sampling from a posterior distribution over models, which is tractable only for simple special cases. This paper develops ensemble sampling, which aims to approximate Thompson sampling while maintaining tractability even in the face of complex models such as neural networks. Ensemble sampling dramatically expands on the range of applica...

  8. Improved sample size determination for attributes and variables sampling

    International Nuclear Information System (INIS)

    Stirpe, D.; Picard, R.R.

    1985-01-01

    Earlier INMM papers have addressed the attributes/variables problem and, under conservative/limiting approximations, have reported analytical solutions for the attributes and variables sample sizes. Through computer simulation of this problem, we have calculated attributes and variables sample sizes as a function of falsification, measurement uncertainties, and required detection probability without using approximations. Using realistic assumptions for uncertainty parameters of measurement, the simulation results support the conclusions: (1) previously used conservative approximations can be expensive because they lead to larger sample sizes than needed; and (2) the optimal verification strategy, as well as the falsification strategy, are highly dependent on the underlying uncertainty parameters of the measurement instruments. 1 ref., 3 figs

  9. Evaluation of the Problem Behavior Frequency Scale-Teacher Report Form for Assessing Behavior in a Sample of Urban Adolescents.

    Science.gov (United States)

    Farrell, Albert D; Goncy, Elizabeth A; Sullivan, Terri N; Thompson, Erin L

    2018-02-01

    This study evaluated the structure and validity of the Problem Behavior Frequency Scale-Teacher Report Form (PBFS-TR) for assessing students' frequency of specific forms of aggression and victimization, and positive behavior. Analyses were conducted on two waves of data from 727 students from two urban middle schools (Sample 1) who were rated by their teachers on the PBFS-TR and the Social Skills Improvement System (SSIS), and on data collected from 1,740 students from three urban middle schools (Sample 2) for whom data on both the teacher and student report version of the PBFS were obtained. Confirmatory factor analyses supported first-order factors representing 3 forms of aggression (physical, verbal, and relational), 3 forms of victimization (physical, verbal and relational), and 2 forms of positive behavior (prosocial behavior and effective nonviolent behavior), and higher-order factors representing aggression, victimization, and positive behavior. Strong measurement invariance was established over gender, grade, intervention condition, and time. Support for convergent validity was found based on correlations between corresponding scales on the PBFS-TR and teacher ratings on the SSIS in Sample 1. Significant correlations were also found between teacher ratings on the PBFS-TR and student ratings of their behavior on the Problem Behavior Frequency Scale-Adolescent Report (PBFS-AR) and a measure of nonviolent behavioral intentions in Sample 2. Overall the findings provided support for the PBFS-TR and suggested that teachers can provide useful data on students' aggressive and prosocial behavior and victimization experiences within the school setting. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  10. STEALTH: a Lagrange explicit finite difference code for solids, structural, and thermohydraulic analysis. Volume 2: sample and verification problems. Computer code manual

    International Nuclear Information System (INIS)

    Hofmann, R.

    1982-08-01

    STEALTH sample and verification problems are presented to help users become familiar with STEALTH capabilities, input, and output. Problems are grouped into articles which are completely self-contained. The pagination in each article is A.n, where A is a unique alphabetic-character article identifier and n is a sequential page number which starts from 1 on the first page of text for each article. Articles concerning new capabilities will be added as they become available. STEALTH sample and verification calculations are divided into the following general categories: transient mechanical calculations dealing with solids; transient mechanical calculations dealing with fluids; transient thermal calculations dealing with solids; transient thermal calculations dealing with fluids; static and quasi-static calculations; and complex boundary interaction calculations

  11. When addiction symptoms and life problems diverge: a latent class analysis of problematic gaming in a representative multinational sample of European adolescents.

    Science.gov (United States)

    Colder Carras, Michelle; Kardefelt-Winther, Daniel

    2018-04-01

    The proposed diagnosis of Internet gaming disorder (IGD) in DSM-5 has been criticized for "borrowing" criteria related to substance addiction, as this might result in misclassifying highly involved gamers as having a disorder. In this paper, we took a person-centered statistical approach to group adolescent gamers by levels of addiction-related symptoms and gaming-related problems, compared these groups to traditional scale scores for IGD, and checked how groups were related to psychosocial well-being using a preregistered analysis plan. We performed latent class analysis and regression with items from IGD and psychosocial well-being scales in a representative sample of 7865 adolescent European gamers. Symptoms and problems matched in only two groups: an IGD class (2.2%) having a high level of symptoms and problems and a Normative class (63.5%) having low levels of symptoms and problems. We also identified two classes comprising 30.9% of our sample that would be misclassified based on their report of gaming-related problems: an Engaged class (7.3%) that seemed to correspond to the engaged gamers described in previous literature, and a Concerned class (23.6%) reporting few symptoms but moderate to high levels of problems. Our findings suggest that a reformulation of IGD is needed. Treating Engaged gamers as having IGD when their poor well-being might not be gaming related may delay appropriate treatment, while Concerned gamers may need help to reduce gaming but would not be identified as such. Additional work to describe the phenomenology of these two groups would help refine diagnosis, prevention and treatment for IGD.

  12. Sampling and examination methods used for TMI-2 samples

    International Nuclear Information System (INIS)

    Marley, A.W.; Akers, D.W.; McIsaac, C.V.

    1988-01-01

    The purpose of this paper is to summarize the sampling and examination techniques that were used in the collection and analysis of TMI-2 samples. Samples ranging from auxiliary building air to core debris were collected and analyzed. Handling of the larger samples and many of the smaller samples had to be done remotely and many standard laboratory analytical techniques were modified to accommodate the extremely high radiation fields associated with these samples. The TMI-2 samples presented unique problems with sampling and the laboratory analysis of prior molten fuel debris. 14 refs., 8 figs

  13. Sharp Bounds by Probability-Generating Functions and Variable Drift

    DEFF Research Database (Denmark)

    Doerr, Benjamin; Fouz, Mahmoud; Witt, Carsten

    2011-01-01

    We introduce to the runtime analysis of evolutionary algorithms two powerful techniques: probability-generating functions and variable drift analysis. They are shown to provide a clean framework for proving sharp upper and lower bounds. As an application, we improve the results by Doerr et al....... (GECCO 2010) in several respects. First, the upper bound on the expected running time of the most successful quasirandom evolutionary algorithm for the OneMax function is improved from 1.28nln n to 0.982nlnn, which breaks the barrier of nln n posed by coupon-collector processes. Compared to the classical...

  14. Validity and Reliability of the Problem Solving Inventory (PSI in a Nationwide Sample of Greek Educators

    Directory of Open Access Journals (Sweden)

    Ntina Kourmousi

    2016-06-01

    Full Text Available The Problem Solving Inventory (PSI is designed to measure adults’ perceptions of problem-solving ability. The presented study aimed to translate it and assess its reliability and validity in a nationwide sample of 3668 Greek educators. In order to evaluate internal consistency reliability, Cronbach’s alpha coefficient was used. The scale’s construct validity was examined by a confirmatory factor analysis (CFA and by investigating its correlation with the Internality, Powerful others and Chance Multidimensional Locus of Control Scale (IPC LOC Scale, the Rosenberg Self-Esteem Scale (RSES and demographic information. Internal consistency reliability was satisfactory with Cronbach’s alphas ranging from 0.79 to 0.91 for all PSI scales. CFA confirmed that the bi-level model fitted the data well. The root mean square error of approximation (RMSEA, the comparative fit index (CFI and the goodness of fit index (GFI values were 0.030, 0.97 and 0.96, respectively, further confirming the bi-level model and the three-factors construct of the PSI. Intercorrelations and correlation coefficients between the PSI, the IPC LOC Scale and the RSES were significant. Age, sex, and working experience differences were found. In conclusion, the Greek version of the PSI was found to have satisfactory psychometric properties and therefore, it can be used to evaluate Greek teachers’ perceptions of their problem-solving skills.

  15. Sampling solution traces for the problem of sorting permutations by signed reversals

    Science.gov (United States)

    2012-01-01

    Background Traditional algorithms to solve the problem of sorting by signed reversals output just one optimal solution while the space of all optimal solutions can be huge. A so-called trace represents a group of solutions which share the same set of reversals that must be applied to sort the original permutation following a partial ordering. By using traces, we therefore can represent the set of optimal solutions in a more compact way. Algorithms for enumerating the complete set of traces of solutions were developed. However, due to their exponential complexity, their practical use is limited to small permutations. A partial enumeration of traces is a sampling of the complete set of traces and can be an alternative for the study of distinct evolutionary scenarios of big permutations. Ideally, the sampling should be done uniformly from the space of all optimal solutions. This is however conjectured to be ♯P-complete. Results We propose and evaluate three algorithms for producing a sampling of the complete set of traces that instead can be shown in practice to preserve some of the characteristics of the space of all solutions. The first algorithm (RA) performs the construction of traces through a random selection of reversals on the list of optimal 1-sequences. The second algorithm (DFALT) consists in a slight modification of an algorithm that performs the complete enumeration of traces. Finally, the third algorithm (SWA) is based on a sliding window strategy to improve the enumeration of traces. All proposed algorithms were able to enumerate traces for permutations with up to 200 elements. Conclusions We analysed the distribution of the enumerated traces with respect to their height and average reversal length. Various works indicate that the reversal length can be an important aspect in genome rearrangements. The algorithms RA and SWA show a tendency to lose traces with high average reversal length. Such traces are however rare, and qualitatively our results

  16. An Investigation of Eighth Grade Students' Problem Posing Skills (Turkey Sample)

    Science.gov (United States)

    Arikan, Elif Esra; Ünal, Hasan

    2015-01-01

    To pose a problem refers to the creative activity for mathematics education. The purpose of the study was to explore the eighth grade students' problem posing ability. Three learning domains such as requiring four operations, fractions and geometry were chosen for this reason. There were two classes which were coded as class A and class B. Class A…

  17. The concerned significant others of people with gambling problems in a national representative sample in Sweden - a 1 year follow-up study.

    Science.gov (United States)

    Svensson, Jessika; Romild, Ulla; Shepherdson, Emma

    2013-11-21

    Research into the impact of problem gambling on close social networks is scarce with the majority of studies only including help-seeking populations. To date only one study has examined concerned significant others (CSOs) from an epidemiological perspective and it did not consider gender. The aim of this study is to examine the health, social support, and financial situations of CSOs in a Swedish representative sample and to examine gender differences. A population study was conducted in Sweden in 2008/09 (n = 15,000, response rate 63%). Respondents were defined as CSOs if they reported that someone close to them currently or previously had problems with gambling. The group of CSOs was further examined in a 1-year follow up (weighted response rate 74% from the 8,165 respondents in the original sample). Comparisons were also made between those defined as CSOs only at baseline (47.7%, n = 554) and those defined as CSOs at both time points. In total, 18.2% of the population were considered CSOs, with no difference between women and men. Male and female CSOs experienced, to a large extent, similar problems including poor mental health, risky alcohol consumption, economic hardship, and arguments with those closest to them. Female CSOs reported less social support than other women and male CSOs had more legal problems and were more afraid of losing their jobs than other men. One year on, several problems remained even if some improvements were found. Both male and female CSOs reported more negative life events in the 1 year follow-up. Although some relationships are unknown, including between the CSOs and the individuals with gambling problems and the causal relationships between being a CSO and the range of associated problems, the results of this study indicate that gambling problems not only affect the gambling individual and their immediate close family but also the wider social network. A large proportion of the population can be defined as a CSO, half of whom are

  18. SOLUTION OF A MULTIVARIATE STRATIFIED SAMPLING PROBLEM THROUGH CHEBYSHEV GOAL PROGRAMMING

    Directory of Open Access Journals (Sweden)

    Mohd. Vaseem Ismail

    2010-12-01

    Full Text Available In this paper, we consider the problem of minimizing the variances for the various characters with fixed (given budget. Each convex objective function is first linearised at its minimal point where it meets the linear cost constraint. The resulting multiobjective linear programming problem is then solved by Chebyshev goal programming. A numerical example is given to illustrate the procedure.

  19. [The methodology and sample description of the National Survey on Addiction Problems in Hungary 2015 (NSAPH 2015)].

    Science.gov (United States)

    Paksi, Borbala; Demetrovics, Zsolt; Magi, Anna; Felvinczi, Katalin

    2017-06-01

    This paper introduces the methods and methodological findings of the National Survey on Addiction Problems in Hungary (NSAPH 2015). Use patterns of smoking, alcohol use and other psychoactive substances were measured as well as that of certain behavioural addictions (problematic gambling - PGSI, DSM-V, eating disorders - SCOFF, problematic internet use - PIUQ, problematic on-line gaming - POGO, problematic social media use - FAS, exercise addictions - EAI-HU, work addiction - BWAS, compulsive buying - CBS). The paper describes the applied measurement techniques, sample selection, recruitment of respondents and the data collection strategy as well. Methodological results of the survey including reliability and validity of the measures are reported. The NSAPH 2015 research was carried out on a nationally representative sample of the Hungarian adult population aged 16-64 yrs (gross sample 2477, net sample 2274 persons) with the age group of 18-34 being overrepresented. Statistical analysis of the weight-distribution suggests that weighting did not create any artificial distortion in the database leaving the representativeness of the sample unaffected. The size of the weighted sample of the 18-64 years old adult population is 1490 persons. The extent of the theoretical margin of error in the weighted sample is ±2,5%, at a reliability level of 95% which is in line with the original data collection plans. Based on the analysis of reliability and the extent of errors beyond sampling within the context of the database we conclude that inconsistencies create relatively minor distortions in cumulative prevalence rates; consequently the database makes possible the reliable estimation of risk factors related to different substance use behaviours. The reliability indexes of measurements used for prevalence estimates of behavioural addictions proved to be appropriate, though the psychometric features in some cases suggest the presence of redundant items. The comparison of

  20. Continuous sampling from distributed streams

    DEFF Research Database (Denmark)

    Graham, Cormode; Muthukrishnan, S.; Yi, Ke

    2012-01-01

    A fundamental problem in data management is to draw and maintain a sample of a large data set, for approximate query answering, selectivity estimation, and query planning. With large, streaming data sets, this problem becomes particularly difficult when the data is shared across multiple distribu......A fundamental problem in data management is to draw and maintain a sample of a large data set, for approximate query answering, selectivity estimation, and query planning. With large, streaming data sets, this problem becomes particularly difficult when the data is shared across multiple...... distributed sites. The main challenge is to ensure that a sample is drawn uniformly across the union of the data while minimizing the communication needed to run the protocol on the evolving data. At the same time, it is also necessary to make the protocol lightweight, by keeping the space and time costs low...... for each participant. In this article, we present communication-efficient protocols for continuously maintaining a sample (both with and without replacement) from k distributed streams. These apply to the case when we want a sample from the full streams, and to the sliding window cases of only the W most...

  1. The link between ethnicity, social disadvantage and mental health problems in a school-based multiethnic sample of children in The Netherlands.

    Science.gov (United States)

    Adriaanse, Marcia; Veling, Wim; Doreleijers, Theo; van Domburgh, Lieke

    2014-11-01

    To investigate to what extent differences in prevalence and types of mental health problems between ethnic minority and majority youth can be explained by social disadvantage. Mental health problems were assessed in a sample of 1,278 schoolchildren (55% Dutch, 32% Moroccan and 13% Turkish; mean age: 12.9 ± 1.8) using the Strengths and Difficulties Questionnaire self-report and teacher report. Measures of family socioeconomic status, neighbourhood deprivation, perceived discrimination, family structure, repeating a school year, housing stability and neighbourhood urbanization were used as indicators of social disadvantage, based on which a cumulative index was created. Ethnic minority youth had more externalizing and fewer internalizing problems than majority youth. Perceived discrimination and living in an unstable social environment were associated with mental health problems, independent of ethnicity. A dose-response relationship was found between social disadvantage and mental health problems. The adjusted odds ratio for mental health problems was 4.16 (95% CI 2.49-6.94) for more than four compared with zero indicators of social disadvantage. Social disadvantage was more common in ethnic minority than in majority youth, explaining part of the differences in prevalence of mental health problems. Ethnic minority youth in the Netherlands have a different profile of mental health problems than majority youth. In all ethnic groups, the risk of mental health problems increases with the degree of social disadvantage. The higher prevalence of externalizing problems among ethnic minority youth is explained partly by their disadvantaged social position. The findings suggest that social factors associated with ethnicity are likely to explain mental health problems in ethnic groups.

  2. Does forming implementation intentions help people with mental health problems to achieve goals? A meta-analysis of experimental studies with clinical and analogue samples.

    Science.gov (United States)

    Toli, Agoro; Webb, Thomas L; Hardy, Gillian E

    2016-03-01

    People struggle to act on the goals that they set themselves, and this gap between intention and action is likely to be exacerbated by mental health problems. Evidence suggests that forming specific if-then plans (or 'implementation intentions') can promote goal attainment and a number of studies have applied such techniques in clinical contexts. However, to date, the extent to which planning can help people with mental health problems has not been systematically examined. The present review used meta-analysis to investigate the effect of if-then planning on goal attainment among people with a DSM-IV/ICD-10 diagnosis (i.e., clinical samples) or scores above a relevant cut-off on clinical measures (i.e., analogue samples). In total, 29 experimental studies, from 18 records, met the inclusion criteria. Excluding one outlying (very large) effect, forming implementation intentions had a large-sized effect on goal attainment (d+ = 0.99, k = 28, N = 1,636). Implementation intentions proved effective across different mental health problems and goals, and in studies with different methodological approaches. Taken together, the findings suggest that forming implementation intentions can be a useful strategy for helping people with mental health problems to achieve various goals and might be usefully integrated into existing treatment approaches. However, further studies are needed addressing a wider range of mental health problems. © 2015 The British Psychological Society.

  3. Sampling and sample preparation methods for the analysis of trace elements in biological material

    International Nuclear Information System (INIS)

    Sansoni, B.; Iyengar, V.

    1978-05-01

    The authors attempt to give a most systamtic possible treatment of the sample taking and sample preparation of biological material (particularly in human medicine) for trace analysis (e.g. neutron activation analysis, atomic absorption spectrometry). Contamination and loss problems are discussed as well as the manifold problems of the different consistency of solid and liquid biological materials, as well as the stabilization of the sample material. The process of dry and wet ashing is particularly dealt with, where new methods are also described. (RB) [de

  4. Interaction matters: quantifying conduct problem × depressive symptoms interaction and its association with adolescent alcohol, cigarette, and marijuana use in a national sample.

    Science.gov (United States)

    Maslowsky, Julie; Schulenberg, John E

    2013-11-01

    Substance use is a major contributor to morbidity and mortality among American adolescents. Conduct problems and depressive symptoms have each been found to be associated with adolescent substance use. Although they are highly comorbid, the role of the interaction of conduct problems and depressive symptoms in substance use is not clear. In national samples of 8th-, 10th-, and 12th-grade students from the Monitoring the Future study, latent moderated structural equation modeling was used to estimate the association of conduct problems, depressive symptoms, and their interaction to the use of alcohol (including binge drinking), cigarettes, and marijuana. Moderation by age and sex was tested. The interaction of conduct problems with depressive symptoms was a strong predictor of substance use, particularly among younger adolescents. With few exceptions, adolescents with high levels of both conduct problems and depressive symptoms used substances most frequently. Conduct problems were a strong positive predictor of substance use, and depressive symptoms were a weak positive predictor. Whereas conduct problems are often thought to be a primary predictor of substance use, this study revealed that depressive symptoms potentiate the relation of conduct problems to substance use. Therefore, substance use prevention efforts should target both depressive symptoms and conduct problems.

  5. Sampling informative/complex a priori probability distributions using Gibbs sampling assisted by sequential simulation

    DEFF Research Database (Denmark)

    Hansen, Thomas Mejer; Mosegaard, Klaus; Cordua, Knud Skou

    2010-01-01

    Markov chain Monte Carlo methods such as the Gibbs sampler and the Metropolis algorithm can be used to sample the solutions to non-linear inverse problems. In principle these methods allow incorporation of arbitrarily complex a priori information, but current methods allow only relatively simple...... this algorithm with the Metropolis algorithm to obtain an efficient method for sampling posterior probability densities for nonlinear inverse problems....

  6. Sleep problems and daytime problem behaviours in children with intellectual disablity

    NARCIS (Netherlands)

    Didden, H.C.M.; Korzilius, H.P.L.M.; Aperloo, B. van; Overloon, C. van; Vries, M. de

    2002-01-01

    BACKGROUND: Sleep problems are common among children with intellectual disability (ID). METHOD: The present study assessed the prevalence of severe sleep problems in a sample of children (n=286) with mild to profound ID who lived at home with their parents(s) in the Netherlands. It also

  7. Encouraging Sixth-Grade Students' Problem-Solving Performance by Teaching through Problem Solving

    Science.gov (United States)

    Bostic, Jonathan D.; Pape, Stephen J.; Jacobbe, Tim

    2016-01-01

    This teaching experiment provided students with continuous engagement in a problem-solving based instructional approach during one mathematics unit. Three sections of sixth-grade mathematics were sampled from a school in Florida, U.S.A. and one section was randomly assigned to experience teaching through problem solving. Students' problem-solving…

  8. Soil sampling

    International Nuclear Information System (INIS)

    Fortunati, G.U.; Banfi, C.; Pasturenzi, M.

    1994-01-01

    This study attempts to survey the problems associated with techniques and strategies of soil sampling. Keeping in mind the well defined objectives of a sampling campaign, the aim was to highlight the most important aspect of representativeness of samples as a function of the available resources. Particular emphasis was given to the techniques and particularly to a description of the many types of samplers which are in use. The procedures and techniques employed during the investigations following the Seveso accident are described. (orig.)

  9. Associations between work family conflict, emotional exhaustion, musculoskeletal pain, and gastrointestinal problems in a sample of business travelers.

    Science.gov (United States)

    Jensen, Maria Therese; Rundmo, Torbjørn

    2015-02-01

    The aim of the study was to examine the associations among work-family conflict (WFC), emotional exhaustion, musculoskeletal (MS) pain, and gastrointestinal problems on a sample of business travelers (n = 2,093). An additional aim was to examine differences in the mentioned relationships among three traveler groups: commuters, national travelers, and international travelers. The study was conducted in a large Norwegian oil and gas company, and the company's business travel database was utilized to examine business travel. Structural equation modeling (SEM) revealed significant relations between WFC and emotional exhaustion and between emotional exhaustion and health problems. Contrary to the expectations, no direct association was found between WFC and health problems. However, we found that emotional exhaustion mediated the relation between WFC and health outcomes. The results from multi-group analysis revealed that associations among WFC, emotional exhaustion, and health-outcomes showed a similar pattern for commuters, national travelers, and international travelers. However, the association between emotional exhaustion and MS pain proved to be significantly stronger for the commuter group compared to the national and international travel groups. Practical implications and the consequences of these findings for future research are discussed. © 2014 Scandinavian Psychological Associations and John Wiley & Sons Ltd.

  10. 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…

  11. Secondary School Students' Reasoning about Conditional Probability, Samples, and Sampling Procedures

    Science.gov (United States)

    Prodromou, Theodosia

    2016-01-01

    In the Australian mathematics curriculum, Year 12 students (aged 16-17) are asked to solve conditional probability problems that involve the representation of the problem situation with two-way tables or three-dimensional diagrams and consider sampling procedures that result in different correct answers. In a small exploratory study, we…

  12. Attention Problems Mediate the Association between Severity of Physical Abuse and Aggressive Behavior in a Sample of Maltreated Early Adolescents

    OpenAIRE

    Garrido, Edward F.; Taussig, Heather N.; Culhane, Sara E.; Raviv, Tali

    2011-01-01

    Empirical evidence has accumulated documenting an association between childhood physical abuse and aggressive behavior. Relatively fewer studies have explored possible mediating mechanisms that may explain this association. The purpose of the current study was to examine whether caregiver- and youth-reported attention problems mediate the association between physical abuse severity and aggressive behavior. A sample of 240 maltreated early adolescents (ages 9–11) and their caregivers were inte...

  13. Initial Reliability and Validity of the Life Satisfaction Scale for Problem Youth in a Sample of Drug Abusing and Conduct Disordered Youth

    Science.gov (United States)

    Donohue, Brad; Teichner, Gordon; Azrin, Nathan; Weintraub, Noah; Crum, Thomas A.; Murphy, Leah; Silver, N. Clayton

    2003-01-01

    Responses to Life Satisfaction Scale for Problem Youth (LSSPY) items were examined in a sample of 193 substance abusing and conduct disordered adolescents. In responding to the LSSPY, youth endorse their percentage of happiness (0 to 100%) in twelve domains (i.e., friendships, family, school, employment/work, fun activities, appearance, sex…

  14. #SochiProblems: Ignorance or Arrogance? / #SochiProblems: ¿ignorancia o arrogancia?

    Directory of Open Access Journals (Sweden)

    Alexander V. Laskin

    2014-10-01

    Full Text Available The study focuses on the twitter conversations about the XXII Winter Olympics Games in Sochi, Russia. Specifically, the study collects and performs content analysis of the tweets tagged with the hashtag #SochiProblems. This study draws a random sample of tweets from every day of the games to achieve a 99% confidence level with 5% confidence interval and uses the framing theory to analyze this sample. The results allow us to determine what substantive and affective frames dominated in the twitter conversations tagged with #SochiProblems hashtag and what was the main focus of the tweets’ content.

  15. Interrelationships between LGBT-Based Victimization, Suicide, and Substance Use Problems in a Diverse Sample of Sexual and Gender Minority Men and Women

    Science.gov (United States)

    Mereish, Ethan H.; O'Cleirigh, C; Bradford, Judith B.

    2013-01-01

    Research has documented significant relationships between sexual and gender minority stress and higher rates of suicidality (i.e., suicidal ideation and attempts) and substance use problems. We examined the potential mediating role of substance use problems on the relationship between sexual and gender minority stress (i.e., victimization based on lesbian, gay, bisexual, or transgender identity; LGBT) and suicidality. A non-probability sample of LGBT patients from a community health center (N = 1457) ranged in age 19 to 70 years. Participants reported history of lifetime suicidal ideation and attempts, and substance use problems, as well as experiences of LGBT-based verbal and physical attacks. Substance use problems were a significant partial mediator between LGBT-based victimization and suicidal ideation and between LGBT-based victimization and suicide attempts for sexual and gender minorities. Nuanced gender differences revealed that substance use problems did not significantly mediate the relationship between victimization and suicide attempts for sexual minority men. Substance use problems may be one insidious pathway that partially mediates the risk effects of sexual and gender minority stress on suicidality. Substances might be a temporary and deleterious coping resource in response to LGBT-based victimization, which have serious effects on suicidal ideation and behaviors. PMID:23535038

  16. The link between infant regulatory problems, temperament traits, maternal depressive symptoms and children's psychopathological symptoms at age three: a longitudinal study in a German at-risk sample.

    Science.gov (United States)

    Sidor, Anna; Fischer, Cristina; Cierpka, Manfred

    2017-01-01

    Difficult conditions during childhood can limit an individual's development in many ways. Factors such as being raised in an at-risk family, child temperamental traits or maternal traits can potentially influence a child's later behaviour. The present study investigated the extent of regulatory problems in 6-month-old infants and their link to temperamental traits and impact on externalizing and internalizing problems at 36 months. Moderating effects of maternal distress and maternal depressive symptoms were tested as well. In a quasi-experimental, longitudinal study, a sample of 185 mother-infant dyads at psychosocial risk was investigated at 6 months with SFS (infants' regulatory problems) and at 3 years with CBCL (children's behavioural problems), EAS (children's temperament), ADS (maternal depressive symptoms) and PSI-SF (maternal stress). A hierarchical regression analysis yielded a significant association between infants' regulatory problems and both externalizing and internalizing behaviour problems at age 3 (accounting for 16% and 14% variance), with both externalizing and internalizing problems being linked to current maternal depressive symptoms (12 and 9% of the variance). Externalizing and internalizing problems were found to be related also to children's temperamental difficulty (18 and 13% of variance) and their negative emotionality. With temperamental traits having been taken into account, only feeding problems at 6 months contributed near-significant to internalizing problems at 3 years. Our results underscore the crucial role of temperament in the path between early regulatory problems and subsequent behavioural difficulties. Children's unfavourable temperamental predispositions such as negative emotionality and generally "difficult temperament" contributed substantially to both externalizing and internalizing behavioural problems in the high-risk sample. The decreased predictive power of regulatory problems following the inclusion of

  17. Sampled-data and discrete-time H2 optimal control

    NARCIS (Netherlands)

    Trentelman, Harry L.; Stoorvogel, Anton A.

    1993-01-01

    This paper deals with the sampled-data H2 optimal control problem. Given a linear time-invariant continuous-time system, the problem of minimizing the H2 performance over all sampled-data controllers with a fixed sampling period can be reduced to a pure discrete-time H2 optimal control problem. This

  18. Manage Your Life Online (MYLO): a pilot trial of a conversational computer-based intervention for problem solving in a student sample.

    Science.gov (United States)

    Gaffney, Hannah; Mansell, Warren; Edwards, Rachel; Wright, Jason

    2014-11-01

    Computerized self-help that has an interactive, conversational format holds several advantages, such as flexibility across presenting problems and ease of use. We designed a new program called MYLO that utilizes the principles of METHOD of Levels (MOL) therapy--based upon Perceptual Control Theory (PCT). We tested the efficacy of MYLO, tested whether the psychological change mechanisms described by PCT mediated its efficacy, and evaluated effects of client expectancy. Forty-eight student participants were randomly assigned to MYLO or a comparison program ELIZA. Participants discussed a problem they were currently experiencing with their assigned program and completed measures of distress, resolution and expectancy preintervention, postintervention and at 2-week follow-up. MYLO and ELIZA were associated with reductions in distress, depression, anxiety and stress. MYLO was considered more helpful and led to greater problem resolution. The psychological change processes predicted higher ratings of MYLO's helpfulness and reductions in distress. Positive expectancies towards computer-based problem solving correlated with MYLO's perceived helpfulness and greater problem resolution, and this was partly mediated by the psychological change processes identified. The findings provide provisional support for the acceptability of the MYLO program in a non-clinical sample although its efficacy as an innovative computer-based aid to problem solving remains unclear. Nevertheless, the findings provide tentative early support for the mechanisms of psychological change identified within PCT and highlight the importance of client expectations on predicting engagement in computer-based self-help.

  19. Psychological problems, self-esteem and body dissatisfaction in a sample of adolescents with brain lesions: A comparison with a control group.

    Science.gov (United States)

    Pastore, Valentina; Colombo, Katia; Maestroni, Deborah; Galbiati, Susanna; Villa, Federica; Recla, Monica; Locatelli, Federica; Strazzer, Sandra

    2015-01-01

    This study aims to describe psychological problems, self-esteem difficulties and body dissatisfaction in a sample of adolescents with acquired brain lesions and to compare them with an age- and gender-matched control group. In an experimental design, the psychological profile of 26 adolescents with brain lesions of traumatic or vascular aetiology, aged 12-18 years, was compared with that of 18 typically-developing subjects. Moreover, within the clinical group, patients with TBI were compared with patients with vascular lesions. The psychological and adaptive profile of the adolescents was assessed by a specific protocol, including CBCL, VABS, RSES, EDI-2 and BES. Adolescents with brain lesions showed more marked psychological problems than their healthy peers; they also presented with a greater impairment of adaptive skills and a lower self-esteem. No significant differences were found between patients with traumatic lesions and patients with vascular lesions. Adolescents with acquired brain lesions were at higher risk to develop psychological and behavioural difficulties. Furthermore, in the clinical sample, some variables such as the long hospitalization and isolation from family and peers were associated to a greater psychological burden than the aetiology of the brain damage.

  20. A twin study exploring the association between childhood emotional and behaviour problems and specific psychotic experiences in a community sample of adolescents.

    Science.gov (United States)

    Shakoor, Sania; McGuire, Philip; Cardno, Alastair G; Freeman, Daniel; Ronald, Angelica

    2018-05-01

    Childhood emotional and behaviour problems are antecedents for later psychopathology. This study investigated genetic and environmental influences shaping the longitudinal association between childhood emotional and behaviour problems and specific PEs. In a community-based twin sample, parents reported on emotional and behaviour problems when twins were ages 7 and 12 years. At age 16 years, specific PEs were measured using self-reports and parent reports. Structural equation model-fitting was conducted. Childhood emotional and behaviour problems were significantly associated with paranoia, cognitive disorganisation and parent-rated negative symptoms in adolescence (mean r = .15-.38), and to a lesser extent with hallucinations, grandiosity and anhedonia (mean r = .04-.12). Genetic influences on childhood emotional and behaviour problems explained significant proportions of variance in adolescent paranoia (4%), cognitive disorganisation (8%) and parent-rated negative symptoms (3%). Unique environmental influences on childhood emotional and behaviour problems explained ≤1% of variance in PEs. Common environmental influences were only relevant for the relationship between childhood emotional and behaviour problems and parent-rated negative symptoms (explaining 28% of variance) and are partly due to correlated rater effects. Childhood emotional and behaviour problems are significantly, if weakly, associated with adolescent PEs. These associations are driven in part by common genetic influences underlying both emotional and behaviour problems and PEs. However, psychotic experiences in adolescence are largely influenced by genetic and environmental factors that are independent of general childhood emotional and behaviour problems, suggesting they are not merely an extension of childhood emotional and behaviour problems. © 2017 The Authors. Journal of Child Psychology and Psychiatry published by John Wiley & Sons Ltd on behalf of Association for Child and

  1. Teknik Sampling Snowball dalam Penelitian Lapangan

    OpenAIRE

    Nina Nurdiani

    2014-01-01

    Field research can be associated with both qualitative and quantitative research methods, depending on the problems faced and the goals to be achieved. The success of data collection in the field research depends on the determination of the appropriate sampling technique, to obtain accurate data, and reliably. In studies that have problems related to specific issues, requiring a non-probability sampling techniques one of which is the snowball sampling technique. This technique is useful for f...

  2. Statistical distribution sampling

    Science.gov (United States)

    Johnson, E. S.

    1975-01-01

    Determining the distribution of statistics by sampling was investigated. Characteristic functions, the quadratic regression problem, and the differential equations for the characteristic functions are analyzed.

  3. Measurement of highly active samples of ultrashort-lived radionuclides and its problems

    International Nuclear Information System (INIS)

    van der Baan, J.G.; Panek, K.J.

    1985-01-01

    The measurement of highly active eluates obtained from the generators for ultrashort-lived radionuclides poses several problems which are briefly discussed by using the example of the /sup 195m/Hg→/sup 195m/Au generator. For overcoming some of the problems, the construction of a multiple single-channel analyzer that allows high count rates, is described, as well as the counting technique applicable for highly active eluates

  4. Gambling problems in the family – A stratified probability sample study of prevalence and reported consequences

    Directory of Open Access Journals (Sweden)

    Øren Anita

    2008-12-01

    Full Text Available Abstract Background Prior studies on the impact of problem gambling in the family mainly include help-seeking populations with small numbers of participants. The objective of the present stratified probability sample study was to explore the epidemiology of problem gambling in the family in the general population. Methods Men and women 16–74 years-old randomly selected from the Norwegian national population database received an invitation to participate in this postal questionnaire study. The response rate was 36.1% (3,483/9,638. Given the lack of validated criteria, two survey questions ("Have you ever noticed that a close relative spent more and more money on gambling?" and "Have you ever experienced that a close relative lied to you about how much he/she gambles?" were extrapolated from the Lie/Bet Screen for pathological gambling. Respondents answering "yes" to both questions were defined as Concerned Significant Others (CSOs. Results Overall, 2.0% of the study population was defined as CSOs. Young age, female gender, and divorced marital status were factors positively associated with being a CSO. CSOs often reported to have experienced conflicts in the family related to gambling, worsening of the family's financial situation, and impaired mental and physical health. Conclusion Problematic gambling behaviour not only affects the gambling individual but also has a strong impact on the quality of life of family members.

  5. The influence of personality traits and emotional and behavioral problems on repetitive nonsuicidal self-injury in a school sample.

    Science.gov (United States)

    Lüdtke, Janine; Weizenegger, Benedict; Rauber, Rachel; Contin, Brigitte; In-Albon, Tina; Schmid, Marc

    2017-04-01

    Nonsuicidal self-injury (NSSI) is highly prevalent among adolescents and associated with various mental health problems and suicidality. Previous studies have found that certain personality traits are related to NSSI behavior, however only few studies examined personality traits in adolescents with NSSI. Our study aimed to assess the relationship between personality traits and emotional and behavioral problems in predicting repetitive NSSI among adolescents from a school sample. Four hundred and forty-seven students (M=14.95years, SD=0.74, 52% male) completed self-report measures on NSSI, personality traits, and emotional and behavioral problems. The past year prevalence of occasional and repetitive NSSI was 4.9% and 6.3% respectively. Repetitive NSSI was significantly associated with female gender, higher levels of age, novelty seeking, harm avoidance, self-transcendence, antisocial behavior, and positive self and lower levels of persistence and self-directedness in univariate analyses. However, multivariate logistic regression analyses indicated that only high levels of antisocial behavior and low levels of self-directedness significantly predicted repetitive NSSI. The association between a lack of self-directedness and NSSI emphasizes the significance of targeting self-directedness in psychotherapy by strengthening self-awareness, affect tolerance and emotion regulation, as well as establishing and pursuing long-term goals. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. On Invertible Sampling and Adaptive Security

    DEFF Research Database (Denmark)

    Ishai, Yuval; Kumarasubramanian, Abishek; Orlandi, Claudio

    2011-01-01

    functionalities was left open. We provide the first convincing evidence that the answer to this question is negative, namely that some (randomized) functionalities cannot be realized with adaptive security. We obtain this result by studying the following related invertible sampling problem: given an efficient...... sampling algorithm A, obtain another sampling algorithm B such that the output of B is computationally indistinguishable from the output of A, but B can be efficiently inverted (even if A cannot). This invertible sampling problem is independently motivated by other cryptographic applications. We show......, under strong but well studied assumptions, that there exist efficient sampling algorithms A for which invertible sampling as above is impossible. At the same time, we show that a general feasibility result for adaptively secure MPC implies that invertible sampling is possible for every A, thereby...

  7. Teknik Sampling Snowball dalam Penelitian Lapangan

    Directory of Open Access Journals (Sweden)

    Nina Nurdiani

    2014-12-01

    Full Text Available Field research can be associated with both qualitative and quantitative research methods, depending on the problems faced and the goals to be achieved. The success of data collection in the field research depends on the determination of the appropriate sampling technique, to obtain accurate data, and reliably. In studies that have problems related to specific issues, requiring a non-probability sampling techniques one of which is the snowball sampling technique. This technique is useful for finding, identifying, selecting and taking samples in a network or chain of relationships. Phased implementation procedures performed through interviews and questionnaires. Snowball sampling technique has strengths and weaknesses in its application. Field research housing sector become the case study to explain this sampling technique.

  8. Gender differences in the associations of gambling activities and suicidal behaviors with problem gambling in a nationally representative French sample.

    Science.gov (United States)

    Husky, Mathilde M; Michel, Grégory; Richard, Jean-Baptiste; Guignard, Romain; Beck, François

    2015-06-01

    The objectives of the present study are to describe gender differences in factors associated with moderate risk and problem gambling. Data were extracted from the 2010 Health Barometer, a large survey on a representative sample of the general population aged 15-85 years living in France (n=27,653), carried out by the National Institute for Health Promotion and Health Education. Data were collected between October 2009 and July 2010. A computer-assisted telephone interview system was used. The findings indicate that men are three times more likely to experience problems with gambling. Men and women have different patterns of gambling activities. Men were more involved with Rapido, internet gambling, sports and racetrack betting, poker, and casino tables, whereas women gambled more often on scratch games. Both men and women engaging in immediate reward games were significantly more likely to experience difficulties with gambling. This association, however, was stronger in women. Furthermore, suicidal ideation and behaviors were more likely to be associated with gambling problems in women as compared to men. The study underscores the importance of considering gender-related differences in the study of gambling behaviors. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Problem Gambling Among Ontario Students: Associations with Substance Abuse, Mental Health Problems, Suicide Attempts, and Delinquent Behaviours.

    Science.gov (United States)

    Cook, Steven; Turner, Nigel E; Ballon, Bruce; Paglia-Boak, Angela; Murray, Robert; Adlaf, Edward M; Ilie, Gabriela; den Dunnen, Wendy; Mann, Robert E

    2015-12-01

    This paper describes gambling problems among Ontario students in 2009 and examines the relationship between gambling problems and substance use problems, mental health problem indicators, and delinquent behaviors. Data were derived from the Ontario Student Drug Use and Health Survey of Ontario students in grades 7-12. Gambling problems were measured as 2 or more of 6 indicators of problem gambling. In total 2.8% of the students surveyed endorsed two or more of the problem gambling items. The odds of problem gamblers reporting mental distress was 4.2 times higher than the rest of the sample and the odds of problem gamblers reporting a suicide attempt were 17.8 times greater than the rest of the sample. In addition compared to the rest of the students, delinquent behaviors were also more common among problem gamblers, including theft (OR = 14.5), selling marijuana (OR = 19.6), gang fights (OR = 11.3) and carrying a handgun (OR = 11.2). In a multivariate analysis, substance-use problems, mental health problems, and the participation in a variety of delinquent behaviors remained significantly associated with youth problem gambling behavior. Students who report problem gambling behaviors show increased substance abuse, mental health, and delinquency/criminal problems that are similar to those seen among adult problem gamblers. The association between these problems suggests that these problems could be addressed in a unified manner.

  10. Energy drink use, problem drinking and drinking motives in a diverse sample of Alaskan college students

    Directory of Open Access Journals (Sweden)

    Monica C. Skewes

    2013-08-01

    Full Text Available Background. Recent research has identified the use of caffeinated energy drinks as a common, potentially risky behaviour among college students that is linked to alcohol misuse and consequences. Research also suggests that energy drink consumption is related to other risky behaviours such as tobacco use, marijuana use and risky sexual activity. Objective. This research sought to examine the associations between frequency of energy drink consumption and problematic alcohol use, alcohol-related consequences, symptoms of alcohol dependence and drinking motives in an ethnically diverse sample of college students in Alaska. We also sought to examine whether ethnic group moderated these associations in the present sample of White, Alaska Native/American Indian and other ethnic minority college students. Design. A paper-and-pencil self-report questionnaire was completed by a sample of 298 college students. Analysis of covariance (ANCOVA was used to examine the effects of energy drink use, ethnic group and energy drink by ethnic group interactions on alcohol outcomes after controlling for variance attributed to gender, age and frequency of binge drinking. Results. Greater energy drink consumption was significantly associated with greater hazardous drinking, alcohol consequences, alcohol dependence symptoms, drinking for enhancement motives and drinking to cope. There were no main effects of ethnic group, and there were no significant energy drink by ethnic group interactions. Conclusion. These findings replicate those of other studies examining the associations between energy drink use and alcohol problems, but contrary to previous research we did not find ethnic minority status to be protective. It is possible that energy drink consumption may serve as a marker for other health risk behaviours among students of various ethnic groups.

  11. Analysis of mathematical problem-solving ability based on metacognition on problem-based learning

    Science.gov (United States)

    Mulyono; Hadiyanti, R.

    2018-03-01

    Problem-solving is the primary purpose of the mathematics curriculum. Problem-solving abilities influenced beliefs and metacognition. Metacognition as superordinate capabilities can direct, regulate cognition and motivation and then problem-solving processes. This study aims to (1) test and analyzes the quality of problem-based learning and (2) investigate the problem-solving capabilities based on metacognition. This research uses mixed method study with The subject research are class XI students of Mathematics and Science at High School Kesatrian 2 Semarang which divided into tacit use, aware use, strategic use and reflective use level. The collecting data using scale, interviews, and tests. The data processed with the proportion of test, t-test, and paired samples t-test. The result shows that the students with levels tacit use were able to complete the whole matter given, but do not understand what and why a strategy is used. Students with aware use level were able to solve the problem, be able to build new knowledge through problem-solving to the indicators, understand the problem, determine the strategies used, although not right. Students on the Strategic ladder Use can be applied and adopt a wide variety of appropriate strategies to solve the issues and achieved re-examine indicators of process and outcome. The student with reflective use level is not found in this study. Based on the results suggested that study about the identification of metacognition in problem-solving so that the characteristics of each level of metacognition more clearly in a more significant sampling. Teachers need to know in depth about the student metacognitive activity and its relationship with mathematical problem solving and another problem resolution.

  12. Efficient Bayesian parameter estimation with implicit sampling and surrogate modeling for a vadose zone hydrological problem

    Science.gov (United States)

    Liu, Y.; Pau, G. S. H.; Finsterle, S.

    2015-12-01

    Parameter inversion involves inferring the model parameter values based on sparse observations of some observables. To infer the posterior probability distributions of the parameters, Markov chain Monte Carlo (MCMC) methods are typically used. However, the large number of forward simulations needed and limited computational resources limit the complexity of the hydrological model we can use in these methods. In view of this, we studied the implicit sampling (IS) method, an efficient importance sampling technique that generates samples in the high-probability region of the posterior distribution and thus reduces the number of forward simulations that we need to run. For a pilot-point inversion of a heterogeneous permeability field based on a synthetic ponded infiltration experiment simu­lated with TOUGH2 (a subsurface modeling code), we showed that IS with linear map provides an accurate Bayesian description of the parameterized permeability field at the pilot points with just approximately 500 forward simulations. We further studied the use of surrogate models to improve the computational efficiency of parameter inversion. We implemented two reduced-order models (ROMs) for the TOUGH2 forward model. One is based on polynomial chaos expansion (PCE), of which the coefficients are obtained using the sparse Bayesian learning technique to mitigate the "curse of dimensionality" of the PCE terms. The other model is Gaussian process regression (GPR) for which different covariance, likelihood and inference models are considered. Preliminary results indicate that ROMs constructed based on the prior parameter space perform poorly. It is thus impractical to replace this hydrological model by a ROM directly in a MCMC method. However, the IS method can work with a ROM constructed for parameters in the close vicinity of the maximum a posteriori probability (MAP) estimate. We will discuss the accuracy and computational efficiency of using ROMs in the implicit sampling procedure

  13. Mathematical solutions to problems in radiological protection involving air sampling and biokinetic modelling

    International Nuclear Information System (INIS)

    Birchall, A.

    1989-04-01

    Intakes of radionuclides are estimated with the personal air sampler (PAS) and by biological monitoring techniques: in the case of plutonium, there are problems with both methods. The statistical variation in activity collected when sampling radioactive aerosols with low number concentrations was investigated. It was shown that the PAS is barely adequate for monitoring plutonium at annual limit of intake (ALI) levels in typical workplace conditions. Two algorithms were developed, enabling non-recycling and recycling compartmental models to be solved. Their accuracy and speed were investigated, and methods of dealing with partitioning, continuous intake, and radioactive progeny were discussed. Analytical, rather than numerical, methods were used. These are faster, and thus ideally suited for implementation on microcomputers. The algorithms enable non-specialists to solve quickly and easily any first order compartmental model, including all the ICRP metabolic models. Non-recycling models with up to 50 compartments can be solved in seconds: recycling models take a little longer. A biokinetic model for plutonium in man following systemic uptake was developed. The proposed ICRP lung model (1989) was represented by a first order compartmental model. These two models were combined, and the recycling algorithm was used to calculate urinary and faecal excretion of plutonium following acute or chronic intake by inhalation. The results indicate much lower urinary excretion than predicted by ICRP Publication 54. (author)

  14. Sampling from a system-theoretic viewpoint

    NARCIS (Netherlands)

    Meinsma, Gjerrit; Mirkin, Leonid

    2009-01-01

    This paper studies a system-theoretic approach to the problem of reconstructing an analog signal from its samples. The idea, borrowed from earlier treatments in the control literature, is to address the problem as a hybrid model-matching problem in which performance is measured by system norms. The

  15. Sleep in a large, multi-university sample of college students: sleep problem prevalence, sex differences, and mental health correlates.

    Science.gov (United States)

    Becker, Stephen P; Jarrett, Matthew A; Luebbe, Aaron M; Garner, Annie A; Burns, G Leonard; Kofler, Michael J

    2018-04-01

    To (1) describe sleep problems in a large, multi-university sample of college students; (2) evaluate sex differences; and (3) examine the unique associations of mental health symptoms (i.e., anxiety, depression, attention-deficit/hyperactivity disorder inattention [ADHD-IN], ADHD hyperactivity-impulsivity [ADHD-HI]) in relation to sleep problems. 7,626 students (70% female; 81% White) ages 18-29 years (M=19.14, SD=1.42) from six universities completed measures assessing mental health symptoms and the Pittsburgh Sleep Quality Index (PSQI). A substantial minority of students endorsed sleep problems across specific sleep components. Specifically, 27% described their sleep quality as poor, 36% reported obtaining less than 7 hours of sleep per night, and 43% reported that it takes >30 minutes to fall asleep at least once per week. 62% of participants met cut-off criteria for poor sleep, though rates differed between females (64%) and males (57%). In structural regression models, both anxiety and depression symptoms were uniquely associated with disruptions in most PSQI sleep component domains. However, anxiety (but not depression) symptoms were uniquely associated with more sleep disturbances and sleep medication use, whereas depression (but not anxiety) symptoms were uniquely associated with increased daytime dysfunction. ADHD-IN symptoms were uniquely associated with poorer sleep quality and increased daytime dysfunction, whereas ADHD-HI symptoms were uniquely associated with more sleep disturbances and less daytime dysfunction. Lastly, ADHD-IN, anxiety, and depression symptoms were each independently associated with poor sleep status. This study documents a high prevalence of poor sleep among college students, some sex differences, and distinct patterns of mental health symptoms in relation to sleep problems. Copyright © 2018. Published by Elsevier Inc.

  16. Geostatistical Sampling Methods for Efficient Uncertainty Analysis in Flow and Transport Problems

    Science.gov (United States)

    Liodakis, Stylianos; Kyriakidis, Phaedon; Gaganis, Petros

    2015-04-01

    In hydrogeological applications involving flow and transport of in heterogeneous porous media the spatial distribution of hydraulic conductivity is often parameterized in terms of a lognormal random field based on a histogram and variogram model inferred from data and/or synthesized from relevant knowledge. Realizations of simulated conductivity fields are then generated using geostatistical simulation involving simple random (SR) sampling and are subsequently used as inputs to physically-based simulators of flow and transport in a Monte Carlo framework for evaluating the uncertainty in the spatial distribution of solute concentration due to the uncertainty in the spatial distribution of hydraulic con- ductivity [1]. Realistic uncertainty analysis, however, calls for a large number of simulated concentration fields; hence, can become expensive in terms of both time and computer re- sources. A more efficient alternative to SR sampling is Latin hypercube (LH) sampling, a special case of stratified random sampling, which yields a more representative distribution of simulated attribute values with fewer realizations [2]. Here, term representative implies realizations spanning efficiently the range of possible conductivity values corresponding to the lognormal random field. In this work we investigate the efficiency of alternative methods to classical LH sampling within the context of simulation of flow and transport in a heterogeneous porous medium. More precisely, we consider the stratified likelihood (SL) sampling method of [3], in which attribute realizations are generated using the polar simulation method by exploring the geometrical properties of the multivariate Gaussian distribution function. In addition, we propose a more efficient version of the above method, here termed minimum energy (ME) sampling, whereby a set of N representative conductivity realizations at M locations is constructed by: (i) generating a representative set of N points distributed on the

  17. Optimal sampling strategy for data mining

    International Nuclear Information System (INIS)

    Ghaffar, A.; Shahbaz, M.; Mahmood, W.

    2013-01-01

    Latest technology like Internet, corporate intranets, data warehouses, ERP's, satellites, digital sensors, embedded systems, mobiles networks all are generating such a massive amount of data that it is getting very difficult to analyze and understand all these data, even using data mining tools. Huge datasets are becoming a difficult challenge for classification algorithms. With increasing amounts of data, data mining algorithms are getting slower and analysis is getting less interactive. Sampling can be a solution. Using a fraction of computing resources, Sampling can often provide same level of accuracy. The process of sampling requires much care because there are many factors involved in the determination of correct sample size. The approach proposed in this paper tries to find a solution to this problem. Based on a statistical formula, after setting some parameters, it returns a sample size called s ufficient sample size , which is then selected through probability sampling. Results indicate the usefulness of this technique in coping with the problem of huge datasets. (author)

  18. Stratified source-sampling techniques for Monte Carlo eigenvalue analysis

    International Nuclear Information System (INIS)

    Mohamed, A.

    1998-01-01

    In 1995, at a conference on criticality safety, a special session was devoted to the Monte Carlo ''Eigenvalue of the World'' problem. Argonne presented a paper, at that session, in which the anomalies originally observed in that problem were reproduced in a much simplified model-problem configuration, and removed by a version of stratified source-sampling. In this paper, stratified source-sampling techniques are generalized and applied to three different Eigenvalue of the World configurations which take into account real-world statistical noise sources not included in the model problem, but which differ in the amount of neutronic coupling among the constituents of each configuration. It is concluded that, in Monte Carlo eigenvalue analysis of loosely-coupled arrays, the use of stratified source-sampling reduces the probability of encountering an anomalous result over that if conventional source-sampling methods are used. However, this gain in reliability is substantially less than that observed in the model-problem results

  19. Generalized sampling in Julia

    DEFF Research Database (Denmark)

    Jacobsen, Christian Robert Dahl; Nielsen, Morten; Rasmussen, Morten Grud

    2017-01-01

    Generalized sampling is a numerically stable framework for obtaining reconstructions of signals in different bases and frames from their samples. For example, one can use wavelet bases for reconstruction given frequency measurements. In this paper, we will introduce a carefully documented toolbox...... for performing generalized sampling in Julia. Julia is a new language for technical computing with focus on performance, which is ideally suited to handle the large size problems often encountered in generalized sampling. The toolbox provides specialized solutions for the setup of Fourier bases and wavelets....... The performance of the toolbox is compared to existing implementations of generalized sampling in MATLAB....

  20. Independent random sampling methods

    CERN Document Server

    Martino, Luca; Míguez, Joaquín

    2018-01-01

    This book systematically addresses the design and analysis of efficient techniques for independent random sampling. Both general-purpose approaches, which can be used to generate samples from arbitrary probability distributions, and tailored techniques, designed to efficiently address common real-world practical problems, are introduced and discussed in detail. In turn, the monograph presents fundamental results and methodologies in the field, elaborating and developing them into the latest techniques. The theory and methods are illustrated with a varied collection of examples, which are discussed in detail in the text and supplemented with ready-to-run computer code. The main problem addressed in the book is how to generate independent random samples from an arbitrary probability distribution with the weakest possible constraints or assumptions in a form suitable for practical implementation. The authors review the fundamental results and methods in the field, address the latest methods, and emphasize the li...

  1. The Relationship between Motor Skills, Perceived Social Support, and Internalizing Problems in a Community Adolescent Sample.

    Science.gov (United States)

    Mancini, Vincent O; Rigoli, Daniela; Heritage, Brody; Roberts, Lynne D; Piek, Jan P

    2016-01-01

    Poor motor skills are associated with a range of psychosocial consequences, including internalizing (anxious and depressive) symptoms. The Elaborated Environmental Stress Hypothesis provides a causal framework to explain this association. The framework posits that motor skills impact internalizing problems through an indirect effect via perceived social support. However, empirical evaluation is required. We examined whether motor skills had an indirect effect on anxious and depressive symptoms via perceived family support domains. This study used a community sample of 93 adolescents (12-16 years). Participants completed measures of motor skills, perceived social support across three dimensions (family, friend, and significant other), depressive symptoms, and anxious symptoms. Age, gender, verbal IQ, and ADHD symptoms were included as control variables. Regression analysis using PROCESS revealed that motor skills had an indirect effect on depressive symptoms via perceived family support, but not by perceived friend support or significant other support. The negative association between motor skills and anxious symptoms was not mediated by any perceived social support domain. Findings are consistent with previous literature indicating an association between motor skills and internalizing problems. However, we identified a different pattern of relationships across anxious and depressive symptoms. While anxiety and depressive symptoms were highly correlated, motor skills had an indirect effect on depressive symptoms via perceived family support only. Our findings highlight the importance of family support as a potential protective factor in the onset of depressive symptoms. This study provides partial support for the Elaborated Environmental Stress Hypothesis, however further research is required.

  2. The Relationship between Motor Skills, Perceived Social Support, and Internalizing Problems in a Community Adolescent Sample

    Directory of Open Access Journals (Sweden)

    Vincent Oreste Mancini

    2016-04-01

    Full Text Available Objectives: Poor motor skills are associated with a range of psychosocial consequences, including internalizing (anxious and depressive symptoms. The Elaborated Environmental Stress Hypothesis provides a causal framework to explain this association. The framework posits that motor skills impact internalizing problems through an indirect effect via perceived social support. However, empirical evaluation is required. We examined whether motor skills has an indirect effect on anxious and depressive symptoms via perceived family support domains. Methods: This study used a community sample of 93 adolescents (12-16 years. Participants completed measures of motor skills, perceived social support across three dimensions (family, friend, and significant other, depressive symptoms, and anxious symptoms. Age, gender, verbal IQ, and ADHD symptoms were included as control variables.Results: Regression analysis using PROCESS revealed that motor skills had an indirect effect on depressive symptoms via perceived family support, but not by perceived friend support or significant other support. The negative association between motor skills and anxious symptoms was not mediated by any perceived social support domain. Conclusions: Findings are consistent with previous literature indicating an association between motor skills and internalizing problems. However, we identified a different pattern of relationships across anxious and depressive symptoms. While anxiety and depressive symptoms were highly correlated, motor skills had an indirect effect on depressive symptoms via perceived family support only. Our findings highlight the importance of family support as a potential protective factor in the onset of depressive symptoms. This study provides partial support for the Elaborated Environmental Stress Hypothesis, however further research is required.

  3. A boundary-optimized rejection region test for the two-sample binomial problem.

    Science.gov (United States)

    Gabriel, Erin E; Nason, Martha; Fay, Michael P; Follmann, Dean A

    2018-03-30

    Testing the equality of 2 proportions for a control group versus a treatment group is a well-researched statistical problem. In some settings, there may be strong historical data that allow one to reliably expect that the control proportion is one, or nearly so. While one-sample tests or comparisons to historical controls could be used, neither can rigorously control the type I error rate in the event the true control rate changes. In this work, we propose an unconditional exact test that exploits the historical information while controlling the type I error rate. We sequentially construct a rejection region by first maximizing the rejection region in the space where all controls have an event, subject to the constraint that our type I error rate does not exceed α for any true event rate; then with any remaining α we maximize the additional rejection region in the space where one control avoids the event, and so on. When the true control event rate is one, our test is the most powerful nonrandomized test for all points in the alternative space. When the true control event rate is nearly one, we demonstrate that our test has equal or higher mean power, averaging over the alternative space, than a variety of well-known tests. For the comparison of 4 controls and 4 treated subjects, our proposed test has higher power than all comparator tests. We demonstrate the properties of our proposed test by simulation and use our method to design a malaria vaccine trial. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  4. Problem of cadmium, arsenic and zinc determination in enviroment samples

    International Nuclear Information System (INIS)

    Malyugin, M.S.; Luzhnova, M.A.; Lontsikh, S.V.

    1983-01-01

    Using the emission spectroscopy technique new information has been obtained on cadmium-, arsenic and zinc content in some reference samples (RS) of rocks and soils not previously certified as to the content of the elements, as well as in nealy issued RS of soils. Metrologic estimation of the results obtained is carried out. A comparison with the atomic-absorption analysis data as well as with those of the neutron-activation-, colorimetric and other methods of the analysis permits to refer to the advantages of using the spectrographic determination technique based on fractionated evaporation, in case of determining cadmium and arsenic in rocks and soils. Consideration of the results of cadmium, arsenic and zinc spectrography contributed greatly to the certification of reference samples of soils

  5. Wet gas sampling

    Energy Technology Data Exchange (ETDEWEB)

    Welker, T.F.

    1997-07-01

    The quality of gas has changed drastically in the past few years. Most gas is wet with hydrocarbons, water, and heavier contaminants that tend to condense if not handled properly. If a gas stream is contaminated with condensables, the sampling of that stream must be done in a manner that will ensure all of the components in the stream are introduced into the sample container as the composite. The sampling and handling of wet gas is extremely difficult under ideal conditions. There are no ideal conditions in the real world. The problems related to offshore operations and other wet gas systems, as well as the transportation of the sample, are additional problems that must be overcome if the analysis is to mean anything to the producer and gatherer. The sampling of wet gas systems is decidedly more difficult than sampling conventional dry gas systems. Wet gas systems were generally going to result in the measurement of one heating value at the inlet of the pipe and a drastic reduction in the heating value of the gas at the outlet end of the system. This is caused by the fallout or accumulation of the heavier products that, at the inlet, may be in the vapor state in the pipeline; hence, the high gravity and high BTU. But, in fact, because of pressure and temperature variances, these liquids condense and form a liquid that is actually running down the pipe as a stream or is accumulated in drips to be blown from the system. (author)

  6. Strategies for achieving high sequencing accuracy for low diversity samples and avoiding sample bleeding using illumina platform.

    Science.gov (United States)

    Mitra, Abhishek; Skrzypczak, Magdalena; Ginalski, Krzysztof; Rowicka, Maga

    2015-01-01

    Sequencing microRNA, reduced representation sequencing, Hi-C technology and any method requiring the use of in-house barcodes result in sequencing libraries with low initial sequence diversity. Sequencing such data on the Illumina platform typically produces low quality data due to the limitations of the Illumina cluster calling algorithm. Moreover, even in the case of diverse samples, these limitations are causing substantial inaccuracies in multiplexed sample assignment (sample bleeding). Such inaccuracies are unacceptable in clinical applications, and in some other fields (e.g. detection of rare variants). Here, we discuss how both problems with quality of low-diversity samples and sample bleeding are caused by incorrect detection of clusters on the flowcell during initial sequencing cycles. We propose simple software modifications (Long Template Protocol) that overcome this problem. We present experimental results showing that our Long Template Protocol remarkably increases data quality for low diversity samples, as compared with the standard analysis protocol; it also substantially reduces sample bleeding for all samples. For comprehensiveness, we also discuss and compare experimental results from alternative approaches to sequencing low diversity samples. First, we discuss how the low diversity problem, if caused by barcodes, can be avoided altogether at the barcode design stage. Second and third, we present modified guidelines, which are more stringent than the manufacturer's, for mixing low diversity samples with diverse samples and lowering cluster density, which in our experience consistently produces high quality data from low diversity samples. Fourth and fifth, we present rescue strategies that can be applied when sequencing results in low quality data and when there is no more biological material available. In such cases, we propose that the flowcell be re-hybridized and sequenced again using our Long Template Protocol. Alternatively, we discuss how

  7. Strategies for achieving high sequencing accuracy for low diversity samples and avoiding sample bleeding using illumina platform.

    Directory of Open Access Journals (Sweden)

    Abhishek Mitra

    Full Text Available Sequencing microRNA, reduced representation sequencing, Hi-C technology and any method requiring the use of in-house barcodes result in sequencing libraries with low initial sequence diversity. Sequencing such data on the Illumina platform typically produces low quality data due to the limitations of the Illumina cluster calling algorithm. Moreover, even in the case of diverse samples, these limitations are causing substantial inaccuracies in multiplexed sample assignment (sample bleeding. Such inaccuracies are unacceptable in clinical applications, and in some other fields (e.g. detection of rare variants. Here, we discuss how both problems with quality of low-diversity samples and sample bleeding are caused by incorrect detection of clusters on the flowcell during initial sequencing cycles. We propose simple software modifications (Long Template Protocol that overcome this problem. We present experimental results showing that our Long Template Protocol remarkably increases data quality for low diversity samples, as compared with the standard analysis protocol; it also substantially reduces sample bleeding for all samples. For comprehensiveness, we also discuss and compare experimental results from alternative approaches to sequencing low diversity samples. First, we discuss how the low diversity problem, if caused by barcodes, can be avoided altogether at the barcode design stage. Second and third, we present modified guidelines, which are more stringent than the manufacturer's, for mixing low diversity samples with diverse samples and lowering cluster density, which in our experience consistently produces high quality data from low diversity samples. Fourth and fifth, we present rescue strategies that can be applied when sequencing results in low quality data and when there is no more biological material available. In such cases, we propose that the flowcell be re-hybridized and sequenced again using our Long Template Protocol. Alternatively

  8. Multiscale sampling model for motion integration.

    Science.gov (United States)

    Sherbakov, Lena; Yazdanbakhsh, Arash

    2013-09-30

    Biologically plausible strategies for visual scene integration across spatial and temporal domains continues to be a challenging topic. The fundamental question we address is whether classical problems in motion integration, such as the aperture problem, can be solved in a model that samples the visual scene at multiple spatial and temporal scales in parallel. We hypothesize that fast interareal connections that allow feedback of information between cortical layers are the key processes that disambiguate motion direction. We developed a neural model showing how the aperture problem can be solved using different spatial sampling scales between LGN, V1 layer 4, V1 layer 6, and area MT. Our results suggest that multiscale sampling, rather than feedback explicitly, is the key process that gives rise to end-stopped cells in V1 and enables area MT to solve the aperture problem without the need for calculating intersecting constraints or crafting intricate patterns of spatiotemporal receptive fields. Furthermore, the model explains why end-stopped cells no longer emerge in the absence of V1 layer 6 activity (Bolz & Gilbert, 1986), why V1 layer 4 cells are significantly more end-stopped than V1 layer 6 cells (Pack, Livingstone, Duffy, & Born, 2003), and how it is possible to have a solution to the aperture problem in area MT with no solution in V1 in the presence of driving feedback. In summary, while much research in the field focuses on how a laminar architecture can give rise to complicated spatiotemporal receptive fields to solve problems in the motion domain, we show that one can reframe motion integration as an emergent property of multiscale sampling achieved concurrently within lamina and across multiple visual areas.

  9. Enhancing sampling design in mist-net bat surveys by accounting for sample size optimization

    OpenAIRE

    Trevelin, Leonardo Carreira; Novaes, Roberto Leonan Morim; Colas-Rosas, Paul François; Benathar, Thayse Cristhina Melo; Peres, Carlos A.

    2017-01-01

    The advantages of mist-netting, the main technique used in Neotropical bat community studies to date, include logistical implementation, standardization and sampling representativeness. Nonetheless, study designs still have to deal with issues of detectability related to how different species behave and use the environment. Yet there is considerable sampling heterogeneity across available studies in the literature. Here, we approach the problem of sample size optimization. We evaluated the co...

  10. Behaviour problems in children with dyslexia.

    Science.gov (United States)

    Heiervang, E; Stevenson, J; Lund, A; Hugdahl, K

    2001-01-01

    The association between behaviour problems and dyslexia was assessed in a population sample of 10- to 12-year-old children. Twenty-five dyslexic children and a matched control group were recruited through a screening in primary schools in the city of Bergen, Norway. For the assessment of behaviour problems the Child Behavior Checklist (CBCL), Teacher Self Report (TRF), and Youth Self Report (YSR) were filled out by parents, teachers, and children, respectively. Information on health and developmental factors were obtained from parents on a separate questionnaire designed for the study. The dyslexic group had significantly more behaviour problems than the control group according to both the CBCL and the TRF. On the YSR there was no significant difference between the groups. Dyslexic children had higher CBCL and TRF scores on the Total Behaviour Problem scale, the Internalizing and Externalizing subdomains, and the Attention problem subscale. The groups differed in social background, prenatal risk factors, birth weight, preschool language problems, and IQ, but these variables showed no relationship to the level of behaviour problems in the present sample. We conclude that pre-adolescent dyslexic children show a wide range of behaviour problems that cannot be attributed to social or developmental background variables.

  11. Monte Carlo source convergence and the Whitesides problem

    International Nuclear Information System (INIS)

    Blomquist, R. N.

    2000-01-01

    The issue of fission source convergence in Monte Carlo eigenvalue calculations is of interest because of the potential consequences of erroneous criticality safety calculations. In this work, the authors compare two different techniques to improve the source convergence behavior of standard Monte Carlo calculations applied to challenging source convergence problems. The first method, super-history powering, attempts to avoid discarding important fission sites between generations by delaying stochastic sampling of the fission site bank until after several generations of multiplication. The second method, stratified sampling of the fission site bank, explicitly keeps the important sites even if conventional sampling would have eliminated them. The test problems are variants of Whitesides' Criticality of the World problem in which the fission site phase space was intentionally undersampled in order to induce marginally intolerable variability in local fission site populations. Three variants of the problem were studied, each with a different degree of coupling between fissionable pieces. Both the superhistory powering method and the stratified sampling method were shown to improve convergence behavior, although stratified sampling is more robust for the extreme case of no coupling. Neither algorithm completely eliminates the loss of the most important fissionable piece, and if coupling is absent, the lost piece cannot be recovered unless its sites from earlier generations have been retained. Finally, criteria for measuring source convergence reliability are proposed and applied to the test problems

  12. Assessment of computer-related health problems among post-graduate nursing students.

    Science.gov (United States)

    Khan, Shaheen Akhtar; Sharma, Veena

    2013-01-01

    The study was conducted to assess computer-related health problems among post-graduate nursing students and to develop a Self Instructional Module for prevention of computer-related health problems in a selected university situated in Delhi. A descriptive survey with co-relational design was adopted. A total of 97 samples were selected from different faculties of Jamia Hamdard by multi stage sampling with systematic random sampling technique. Among post-graduate students, majority of sample subjects had average compliance with computer-related ergonomics principles. As regards computer related health problems, majority of post graduate students had moderate computer-related health problems, Self Instructional Module developed for prevention of computer-related health problems was found to be acceptable by the post-graduate students.

  13. Particle Swarm Optimization and Uncertainty Assessment in Inverse Problems

    Directory of Open Access Journals (Sweden)

    José L. G. Pallero

    2018-01-01

    Full Text Available Most inverse problems in the industry (and particularly in geophysical exploration are highly underdetermined because the number of model parameters too high to achieve accurate data predictions and because the sampling of the data space is scarce and incomplete; it is always affected by different kinds of noise. Additionally, the physics of the forward problem is a simplification of the reality. All these facts result in that the inverse problem solution is not unique; that is, there are different inverse solutions (called equivalent, compatible with the prior information that fits the observed data within similar error bounds. In the case of nonlinear inverse problems, these equivalent models are located in disconnected flat curvilinear valleys of the cost-function topography. The uncertainty analysis consists of obtaining a representation of this complex topography via different sampling methodologies. In this paper, we focus on the use of a particle swarm optimization (PSO algorithm to sample the region of equivalence in nonlinear inverse problems. Although this methodology has a general purpose, we show its application for the uncertainty assessment of the solution of a geophysical problem concerning gravity inversion in sedimentary basins, showing that it is possible to efficiently perform this task in a sampling-while-optimizing mode. Particularly, we explain how to use and analyze the geophysical models sampled by exploratory PSO family members to infer different descriptors of nonlinear uncertainty.

  14. Problems with sampling desert tortoises: A simulation analysis based on field data

    Science.gov (United States)

    Freilich, J.E.; Camp, R.J.; Duda, J.J.; Karl, A.E.

    2005-01-01

    The desert tortoise (Gopherus agassizii) was listed as a U.S. threatened species in 1990 based largely on population declines inferred from mark-recapture surveys of 2.59-km2 (1-mi2) plots. Since then, several census methods have been proposed and tested, but all methods still pose logistical or statistical difficulties. We conducted computer simulations using actual tortoise location data from 2 1-mi2 plot surveys in southern California, USA, to identify strengths and weaknesses of current sampling strategies. We considered tortoise population estimates based on these plots as "truth" and then tested various sampling methods based on sampling smaller plots or transect lines passing through the mile squares. Data were analyzed using Schnabel's mark-recapture estimate and program CAPTURE. Experimental subsampling with replacement of the 1-mi2 data using 1-km2 and 0.25-km2 plot boundaries produced data sets of smaller plot sizes, which we compared to estimates from the 1-mi 2 plots. We also tested distance sampling by saturating a 1-mi 2 site with computer simulated transect lines, once again evaluating bias in density estimates. Subsampling estimates from 1-km2 plots did not differ significantly from the estimates derived at 1-mi2. The 0.25-km2 subsamples significantly overestimated population sizes, chiefly because too few recaptures were made. Distance sampling simulations were biased 80% of the time and had high coefficient of variation to density ratios. Furthermore, a prospective power analysis suggested limited ability to detect population declines as high as 50%. We concluded that poor performance and bias of both sampling procedures was driven by insufficient sample size, suggesting that all efforts must be directed to increasing numbers found in order to produce reliable results. Our results suggest that present methods may not be capable of accurately estimating desert tortoise populations.

  15. Bayesian Simultaneous Estimation for Means in k Sample Problems

    OpenAIRE

    Imai, Ryo; Kubokawa, Tatsuya; Ghosh, Malay

    2017-01-01

    This paper is concerned with the simultaneous estimation of k population means when one suspects that the k means are nearly equal. As an alternative to the preliminary test estimator based on the test statistics for testing hypothesis of equal means, we derive Bayesian and minimax estimators which shrink individual sample means toward a pooled mean estimator given under the hypothesis. Interestingly, it is shown that both the preliminary test estimator and the Bayesian minimax shrinkage esti...

  16. Statistical sampling plans

    International Nuclear Information System (INIS)

    Jaech, J.L.

    1984-01-01

    In auditing and in inspection, one selects a number of items by some set of procedures and performs measurements which are compared with the operator's values. This session considers the problem of how to select the samples to be measured, and what kinds of measurements to make. In the inspection situation, the ultimate aim is to independently verify the operator's material balance. The effectiveness of the sample plan in achieving this objective is briefly considered. The discussion focuses on the model plant

  17. Efficient maximal Poisson-disk sampling and remeshing on surfaces

    KAUST Repository

    Guo, Jianwei; Yan, Dongming; Jia, Xiaohong; Zhang, Xiaopeng

    2015-01-01

    Poisson-disk sampling is one of the fundamental research problems in computer graphics that has many applications. In this paper, we study the problem of maximal Poisson-disk sampling on mesh surfaces. We present a simple approach that generalizes the 2D maximal sampling framework to surfaces. The key observation is to use a subdivided mesh as the sampling domain for conflict checking and void detection. Our approach improves the state-of-the-art approach in efficiency, quality and the memory consumption.

  18. Efficient maximal Poisson-disk sampling and remeshing on surfaces

    KAUST Repository

    Guo, Jianwei

    2015-02-01

    Poisson-disk sampling is one of the fundamental research problems in computer graphics that has many applications. In this paper, we study the problem of maximal Poisson-disk sampling on mesh surfaces. We present a simple approach that generalizes the 2D maximal sampling framework to surfaces. The key observation is to use a subdivided mesh as the sampling domain for conflict checking and void detection. Our approach improves the state-of-the-art approach in efficiency, quality and the memory consumption.

  19. Succinct Sampling from Discrete Distributions

    DEFF Research Database (Denmark)

    Bringmann, Karl; Larsen, Kasper Green

    2013-01-01

    We revisit the classic problem of sampling from a discrete distribution: Given n non-negative w-bit integers x_1,...,x_n, the task is to build a data structure that allows sampling i with probability proportional to x_i. The classic solution is Walker's alias method that takes, when implemented...

  20. Drug-related problems in a sample of outpatients with chronic diseases: a cross-sectional study from Jordan

    Directory of Open Access Journals (Sweden)

    Al-Azzam SI

    2016-02-01

    Full Text Available Sayer I Al-Azzam,1 Karem H Alzoubi,1 Salah AbuRuz,2 Qais Alefan1 1Department of Clinical Pharmacy, Faculty of Pharmacy, Jordan University of Science and Technology, Irbid, 2Department of Biopharmaceutics and Clinical Pharmacy, Faculty of Pharmacy, University of Jordan, Amman, Jordan Abstract: Optimization of drug therapy and preventing drug-related problems (DRPs are major factors to improve health care, reduce expenditure, and potentially save lives. This study aimed at describing the types, numbers, and frequencies of DRPs in the outpatient settings of a group of hospitals in Jordan. The study was set in the cardiology, endocrine, and respiratory outpatient clinics of five major hospitals in Jordan. Patients who visited the above clinics during the period from September 2012 to December 2013, were candidates for this study. Each included subject was fully assessed for DRPs by clinical pharmacists according to a specially designed and validated pharmaceutical care manual. The main outcome measures were the number and types of DRPs. Data were collected from 2,898 patients (mean age ± standard deviation: 56.59±13.5 years. The total number of identified DRPs was 32,348, with an average of 11.2 DRPs per patient. The most common DRPs were a need for additional or more frequent monitoring, a problem in patients’ adherence to self-care activities or nonpharmacological therapy, and that the patient was not given instruction in or did not understand nonpharmacological therapy or self-care advice. The numbers of DRPs per patient in our sample were associated with older age (>57 years, being unmarried, having an education level of high school or less, not having health insurance, and the presence of certain clinical conditions, including hypertension, diabetes mellitus, dyslipidemia, ischemic heart disease, cardiac catheterization, heart failure, and gout. In conclusion, implementation of clinical pharmacy services is a strategy to limit DRPs

  1. Mental health problems are associated with low-frequency fluctuations in reaction time in a large general population sample. The TRAILS study.

    Science.gov (United States)

    Bastiaansen, J A; van Roon, A M; Buitelaar, J K; Oldehinkel, A J

    2015-02-01

    Increased intra-subject reaction time variability (RT-ISV) as coarsely measured by the standard deviation (RT-SD) has been associated with many forms of psychopathology. Low-frequency RT fluctuations, which have been associated with intrinsic brain rhythms occurring approximately every 15-40s, have been shown to add unique information for ADHD. In this study, we investigated whether these fluctuations also relate to attentional problems in the general population, and contribute to the two major domains of psychopathology: externalizing and internalizing problems. RT was monitored throughout a self-paced sustained attention task (duration: 9.1 ± 1.2 min) in a Dutch population cohort of young adults (n=1455, mean age: 19.0 ± 0.6 years, 55.1% girls). To characterize temporal fluctuations in RT, we performed direct Fourier Transform on externally validated frequency bands based on frequency ranges of neuronal oscillations: Slow-5 (0.010-0.027 Hz), Slow-4 (0.027-0.073 Hz), and three additional higher frequency bands. Relative magnitude of Slow-4 fluctuations was the primary predictor in regression models for attentional, internalizing and externalizing problems (measured by the Adult Self-Report questionnaire). Additionally, stepwise regression models were created to investigate (a) whether Slow-4 significantly improved the prediction of problem behaviors beyond the RT-SD and (b) whether the other frequency bands provided important additional information. The magnitude of Slow-4 fluctuations significantly predicted attentional and externalizing problems and even improved model fit after modeling RT-SD first (R(2) change=0.6%, Pfrequency bands provided additional information. Low-frequency RT fluctuations have added predictive value for attentional and externalizing, but not internalizing problems beyond global differences in variability. This study extends previous findings in clinical samples of children with ADHD to adolescents from the general population and

  2. Sampling methodology and PCB analysis

    International Nuclear Information System (INIS)

    Dominelli, N.

    1995-01-01

    As a class of compounds PCBs are extremely stable and resist chemical and biological decomposition. Diluted solutions exposed to a range of environmental conditions will undergo some preferential degradation and the resulting mixture may differ considerably from the original PCB used as insulating fluid in electrical equipment. The structure of mixtures of PCBs (synthetic compounds prepared by direct chlorination of biphenyl with chlorine gas) is extremely complex and presents a formidable analytical problem, further complicated by the presence of PCBs as contaminants in oils to soils to water. This paper provides some guidance into sampling and analytical procedures; it also points out various potential problems encountered during these processes. The guidelines provided deal with sample collection, storage and handling, sample stability, laboratory analysis (usually gas chromatography), determination of PCB concentration, calculation of total PCB content, and quality assurance. 1 fig

  3. Monolith Chromatography as Sample Preparation Step in Virome Studies of Water Samples.

    Science.gov (United States)

    Gutiérrez-Aguirre, Ion; Kutnjak, Denis; Rački, Nejc; Rupar, Matevž; Ravnikar, Maja

    2018-01-01

    Viruses exist in aquatic media and many of them use this media as transmission route. Next-generation sequencing (NGS) technologies have opened new doors in virus research, allowing also to reveal a hidden diversity of viral species in aquatic environments. Not surprisingly, many of the newly discovered viruses are found in environmental fresh and marine waters. One of the problems in virome research can be the low amount of viral nucleic acids present in the sample in contrast to the background ones (host, eukaryotic, prokaryotic, environmental). Therefore, virus enrichment prior to NGS is necessary in many cases. In water samples, an added problem resides in the low concentration of viruses typically present in aquatic media. Different concentration strategies have been used to overcome such limitations. CIM monoliths are a new generation of chromatographic supports that due to their particular structural characteristics are very efficient in concentration and purification of viruses. In this chapter, we describe the use of CIM monolithic chromatography for sample preparation step in NGS studies targeting viruses in fresh or marine water. The step-by-step protocol will include a case study where CIM concentration was used to study the virome of a wastewater sample using NGS.

  4. Iterative importance sampling algorithms for parameter estimation

    OpenAIRE

    Morzfeld, Matthias; Day, Marcus S.; Grout, Ray W.; Pau, George Shu Heng; Finsterle, Stefan A.; Bell, John B.

    2016-01-01

    In parameter estimation problems one computes a posterior distribution over uncertain parameters defined jointly by a prior distribution, a model, and noisy data. Markov Chain Monte Carlo (MCMC) is often used for the numerical solution of such problems. An alternative to MCMC is importance sampling, which can exhibit near perfect scaling with the number of cores on high performance computing systems because samples are drawn independently. However, finding a suitable proposal distribution is ...

  5. Mycotoxin Cocktail in the Samples of Oilseed Cake from Early Maturing Cotton Varieties Associated with Cattle Feeding Problems.

    Science.gov (United States)

    Yunus, Agha W; Sulyok, Michael; Böhm, Josef

    2015-06-12

    Cottonseed cake in South East Asia has been associated with health issues in ruminants in the recent years. The present study was carried out to investigate the health issues associated with cottonseed cake feeding in dairy animals in Pakistan. All the cake samples were confirmed to be from early maturing cotton varieties (maturing prior to or during Monsoon). A survey of the resource persons indicated that the feeding problems with cottonseed cake appeared after 4-5 months of post-production storage. All the cake samples had heavy bacterial counts, and contaminated with over a dozen different fungal genera. Screening for toxins revealed co-contamination with toxic levels of nearly a dozen mycotoxins including aflatoxin B1 + B2 (556 to 5574 ppb), ochratoxin A + B (47 to 2335 ppb), cyclopiazonic acid (1090 to 6706 ppb), equisetin (2226 to 12672 ppb), rubrofusarin (81 to 1125), tenuazonic acid (549 to 9882 ppb), 3-nitropropionic acid (111 to 1032 ppb), and citrinin (29 to 359 ppb). Two buffalo calves in a diagnostic feed trial also showed signs of complex toxicity. These results indicate that inappropriate processing and storage of the cake, in the typical conditions of the subcontinent, could be the main contributory factors regarding the low quality of cottonseed cake.

  6. Relationship of attention-deficit/hyperactivity disorder symptom severity with severity of alcohol-related problems in a sample of inpatients with alcohol use disorder

    Directory of Open Access Journals (Sweden)

    Bozkurt M

    2016-07-01

    Full Text Available Muge Bozkurt,1 Cuneyt Evren,1 Gokhan Umut,1 Bilge Evren2 1Research, Treatment and Training Center for Alcohol and Substance Dependence, Bakirkoy Prof Dr Mazhar Osman Training and Research Hospital for Psychiatry, Neurology and Neurosurgery, 2Department of Psychiatry, Baltalimani State Hospital for Muskuloskeletal Disorders, Istanbul, Turkey Purpose: Attention-deficit/hyperactivity disorder (ADHD has been shown to be related to a higher risk of developing psychiatric problems such as depressive disorders, substance use disorder, and impulsivity. Adults who have comorbid ADHD and alcohol use disorder (AUD are at greater risk of negative outcomes. Thus, it is important to evaluate the relationship of ADHD symptoms and the severity of alcohol-related problems among patients with AUD. The aim of the present study was to evaluate the effect of ADHD symptoms on severity of alcohol-related problems, while controlling the effects of depression and impulsivity in a sample of inpatients with AUD. Patients and methods: Participants (n=190 were evaluated with the Beck Depression Inventory, the Short Form Barratt Impulsiveness Scale, the Michigan Alcohol Screening Test, and the Adult ADHD Self-Report Scale. Results: Severity of the scale scores was positively correlated with each other. Although severity of depression and impulsivity (particularly non-planning impulsivity predicted the severity of alcohol-related problems in a linear regression model, when severity of ADHD symptoms was included in the analysis, the inattentive subscale score, in particular, predicted the severity of alcohol-related problems together with non-planning impulsivity, whereas depression was no longer a predictor. Conclusion: These findings suggest that, together with non-planning impulsivity, symptoms of ADHD (particularly inattentive factor are an important factor that predict alcohol-related problems, while controlling the severity of depressive symptoms among inpatients

  7. An unbiased estimator of the variance of simple random sampling using mixed random-systematic sampling

    OpenAIRE

    Padilla, Alberto

    2009-01-01

    Systematic sampling is a commonly used technique due to its simplicity and ease of implementation. The drawback of this simplicity is that it is not possible to estimate the design variance without bias. There are several ways to circumvent this problem. One method is to suppose that the variable of interest has a random order in the population, so the sample variance of simple random sampling without replacement is used. By means of a mixed random - systematic sample, an unbiased estimator o...

  8. A comparison of fitness-case sampling methods for genetic programming

    Science.gov (United States)

    Martínez, Yuliana; Naredo, Enrique; Trujillo, Leonardo; Legrand, Pierrick; López, Uriel

    2017-11-01

    Genetic programming (GP) is an evolutionary computation paradigm for automatic program induction. GP has produced impressive results but it still needs to overcome some practical limitations, particularly its high computational cost, overfitting and excessive code growth. Recently, many researchers have proposed fitness-case sampling methods to overcome some of these problems, with mixed results in several limited tests. This paper presents an extensive comparative study of four fitness-case sampling methods, namely: Interleaved Sampling, Random Interleaved Sampling, Lexicase Selection and Keep-Worst Interleaved Sampling. The algorithms are compared on 11 symbolic regression problems and 11 supervised classification problems, using 10 synthetic benchmarks and 12 real-world data-sets. They are evaluated based on test performance, overfitting and average program size, comparing them with a standard GP search. Comparisons are carried out using non-parametric multigroup tests and post hoc pairwise statistical tests. The experimental results suggest that fitness-case sampling methods are particularly useful for difficult real-world symbolic regression problems, improving performance, reducing overfitting and limiting code growth. On the other hand, it seems that fitness-case sampling cannot improve upon GP performance when considering supervised binary classification.

  9. Preschool Boys' Development of Emotional Self-regulation Strategies in a Sample At-risk for Behavior Problems

    Science.gov (United States)

    Supplee, Lauren H.; Skuban, Emily Moye; Trentacosta, Christopher J.; Shaw, Daniel S.; Stoltz, Emilee

    2011-01-01

    Little longitudinal research has been conducted on changes in children's emotional self-regulation strategy (SRS) use after infancy, particularly for children at risk. The current study examined changes in boys' emotional SRS from toddlerhood through preschool. Repeated observational assessments using delay of gratification tasks at ages 2, 3, and 4 were examined with both variable- and person-oriented analyses in a low-income sample of boys (N = 117) at-risk for early problem behavior. Results were consistent with theory on emotional SRS development in young children. Children initially used more emotion-focused SRS (e.g., comfort seeking) and transitioned to greater use of planful SRS (e.g., distraction) by age 4. Person-oriented analysis using trajectory analysis found similar patterns from 2–4, with small groups of boys showing delayed movement away from emotion-focused strategies or delay in the onset of regular use of distraction. The results provide a foundation for future research to examine the development of SRS in low-income young children. PMID:21675542

  10. Statistics and sampling in transuranic studies

    International Nuclear Information System (INIS)

    Eberhardt, L.L.; Gilbert, R.O.

    1980-01-01

    The existing data on transuranics in the environment exhibit a remarkably high variability from sample to sample (coefficients of variation of 100% or greater). This chapter stresses the necessity of adequate sample size and suggests various ways to increase sampling efficiency. Objectives in sampling are regarded as being of great importance in making decisions as to sampling methodology. Four different classes of sampling methods are described: (1) descriptive sampling, (2) sampling for spatial pattern, (3) analytical sampling, and (4) sampling for modeling. A number of research needs are identified in the various sampling categories along with several problems that appear to be common to two or more such areas

  11. Development, problem behavior, and quality of life in a population based sample of eight-year-old children with Down syndrome.

    Directory of Open Access Journals (Sweden)

    Helma B M van Gameren-Oosterom

    Full Text Available OBJECTIVE: Children with Down syndrome (DS have delayed psychomotor development. We investigated levels of development, problem behavior, and Health-Related Quality of Life (HRQoL in a population sample of Dutch eight-year-old children with DS. Developmental outcomes were compared with normative data of eight-year-old children from the general population. METHOD: Over a three-year-period all parents with an eight-year-old child with DS were approached by the national parent organization. Developmental skills were assessed by means of the McCarthy Scales of Children's Ability. To measure emotional and behavioral problems we used the Child Behavior Checklist. HRQoL was assessed with the TNO-AZL Children's Quality of Life questionnaire. Analyses of variance were applied to compare groups. RESULTS: A total of 337 children participated. Mean developmental age was substantially lower than mean calendar age (3.9 years, SD 0.87 and 8.1 years, SD 0.15 respectively. Mean developmental age was significantly lower among boys than girls (3.6 (SD 0.85 and 4.2 years (SD 0.82 respectively; p<0.001. Compared with the general population, children with DS had more emotional and behavioral problems (p<0.001. However on the anxious/depressed scale, they scored significantly more favorably (p<0.001. Significantly lower HRQoL scores for the scales gross motor skills, autonomy, social functioning and cognitive functioning were found (p-values<0.001. Hardly any differences were observed for the scales physical complaints, positive and negative emotions. CONCLUSION: Eight-year-old children with DS have an average developmental delay of four years, more often have emotional and behavioral problems, and have a less favorable HRQoL compared with children from the general population.

  12. Classes of disruptive behavior problems in referred adolescents

    NARCIS (Netherlands)

    Nijs, P.F.; van Lier, P.A.C.; Verhulst, F.C.; Ferdinand, R.F.

    2007-01-01

    Background: Previous studies have found considerable overlap between attention/hyperactivity problems, aggressive/oppositional problems and delinquent/conduct problems in adolescents. Sampling and Methods: Mothers of 1,965 11- to 18-year-olds (1,116 boys, 849 girls), referred to mental health

  13. Problem gambling and family violence: prevalence and patterns in treatment-seekers.

    Science.gov (United States)

    Dowling, N A; Jackson, A C; Suomi, A; Lavis, T; Thomas, S A; Patford, J; Harvey, P; Battersby, M; Koziol-McLain, J; Abbott, M; Bellringer, M E

    2014-12-01

    The primary aim of this study was to explore the prevalence and patterns of family violence in treatment-seeking problem gamblers. Secondary aims were to identify the prevalence of problem gambling in a family violence victimisation treatment sample and to explore the relationship between problem gambling and family violence in other treatment-seeking samples. Clients from 15 Australian treatment services were systematically screened for problem gambling using the Brief Bio-Social Gambling Screen and for family violence using single victimisation and perpetration items adapted from the Hurt-Insulted-Threatened-Screamed (HITS): gambling services (n=463), family violence services (n=95), alcohol and drug services (n=47), mental health services (n=51), and financial counselling services (n=48). The prevalence of family violence in the gambling sample was 33.9% (11.0% victimisation only, 6.9% perpetration only, and 16.0% both victimisation and perpetration). Female gamblers were significantly more likely to report victimisation only (16.5% cf. 7.8%) and both victimisation and perpetration (21.2% cf. 13.0%) than male gamblers. There were no other demographic differences in family violence prevalence estimates. Gamblers most commonly endorsed their parents as both the perpetrators and victims of family violence, followed by current and former partners. The prevalence of problem gambling in the family violence sample was 2.2%. The alcohol and drug (84.0%) and mental health (61.6%) samples reported significantly higher rates of any family violence than the gambling sample, while the financial counselling sample (10.6%) reported significantly higher rates of problem gambling than the family violence sample. The findings of this study support substantial comorbidity between problem gambling and family violence, although this may be accounted for by a high comorbidity with alcohol and drug use problems and other psychiatric disorders. They highlight the need for routine

  14. Automatic remote sampling and delivery system incorporating decontamination and disposal of sample bottles

    International Nuclear Information System (INIS)

    Savarkar, V.K.; Mishra, A.K.; Bajpai, D.D.; Nair, M.K.T.

    1990-01-01

    The present generation of reprocessing plants have sampling and delivery systems that have to be operated manually with its associated problems. The complete automation and remotisation of sampling system has hence been considered to reduce manual intervention and personnel exposure. As a part of this scheme an attempt to automate and remotise various steps in sampling system has been made. This paper discusses in detail the development work carried out in this area as well as the tests conducted to incorporate the same in the existing plants. (author). 3 figs

  15. Imitation and luck: an experimental study on social sampling

    NARCIS (Netherlands)

    Offerman, T.; Schotter, A.

    2008-01-01

    In this paper, we present the results of two experiments on social sampling, where people make a risky decision after they have sampled the behavior of others who have done exactly the same problem before them. In an individual decision making problem as well as in the take-over game, the simple

  16. Enhanced, targeted sampling of high-dimensional free-energy landscapes using variationally enhanced sampling, with an application to chignolin.

    Science.gov (United States)

    Shaffer, Patrick; Valsson, Omar; Parrinello, Michele

    2016-02-02

    The capabilities of molecular simulations have been greatly extended by a number of widely used enhanced sampling methods that facilitate escaping from metastable states and crossing large barriers. Despite these developments there are still many problems which remain out of reach for these methods which has led to a vigorous effort in this area. One of the most important problems that remains unsolved is sampling high-dimensional free-energy landscapes and systems that are not easily described by a small number of collective variables. In this work we demonstrate a new way to compute free-energy landscapes of high dimensionality based on the previously introduced variationally enhanced sampling, and we apply it to the miniprotein chignolin.

  17. Enhanced, targeted sampling of high-dimensional free-energy landscapes using variationally enhanced sampling, with an application to chignolin

    Science.gov (United States)

    Shaffer, Patrick; Valsson, Omar; Parrinello, Michele

    2016-01-01

    The capabilities of molecular simulations have been greatly extended by a number of widely used enhanced sampling methods that facilitate escaping from metastable states and crossing large barriers. Despite these developments there are still many problems which remain out of reach for these methods which has led to a vigorous effort in this area. One of the most important problems that remains unsolved is sampling high-dimensional free-energy landscapes and systems that are not easily described by a small number of collective variables. In this work we demonstrate a new way to compute free-energy landscapes of high dimensionality based on the previously introduced variationally enhanced sampling, and we apply it to the miniprotein chignolin. PMID:26787868

  18. Importance sampling of rare events in chaotic systems

    DEFF Research Database (Denmark)

    Leitão, Jorge C.; Parente Lopes, João M.Viana; Altmann, Eduardo G.

    2017-01-01

    space of chaotic systems. As examples of our general framework we compute the distribution of finite-time Lyapunov exponents (in different chaotic maps) and the distribution of escape times (in transient-chaos problems). Our methods sample exponentially rare states in polynomial number of samples (in......Finding and sampling rare trajectories in dynamical systems is a difficult computational task underlying numerous problems and applications. In this paper we show how to construct Metropolis-Hastings Monte-Carlo methods that can efficiently sample rare trajectories in the (extremely rough) phase...... both low- and high-dimensional systems). An open-source software that implements our algorithms and reproduces our results can be found in reference [J. Leitao, A library to sample chaotic systems, 2017, https://github.com/jorgecarleitao/chaospp]....

  19. Response problems in a vacation panel study

    Science.gov (United States)

    Christine A. Vogt; Susan I. Stewart

    2001-01-01

    This paper investigates response problems encountered in a panel study of travel behavior. Though the overall response rate to the three-wave panel study was acceptable (over 60%), three types of response problems were encountered: refusal, non-response, and attrition. In a follow-up phone survey, a sample of individuals from each problem response group was questioned...

  20. SamplingStrata: An R Package for the Optimization of Strati?ed Sampling

    Directory of Open Access Journals (Sweden)

    Giulio Barcaroli

    2014-11-01

    Full Text Available When designing a sampling survey, usually constraints are set on the desired precision levels regarding one or more target estimates (the Ys. If a sampling frame is available, containing auxiliary information related to each unit (the Xs, it is possible to adopt a stratified sample design. For any given strati?cation of the frame, in the multivariate case it is possible to solve the problem of the best allocation of units in strata, by minimizing a cost function sub ject to precision constraints (or, conversely, by maximizing the precision of the estimates under a given budget. The problem is to determine the best stratification in the frame, i.e., the one that ensures the overall minimal cost of the sample necessary to satisfy precision constraints. The Xs can be categorical or continuous; continuous ones can be transformed into categorical ones. The most detailed strati?cation is given by the Cartesian product of the Xs (the atomic strata. A way to determine the best stratification is to explore exhaustively the set of all possible partitions derivable by the set of atomic strata, evaluating each one by calculating the corresponding cost in terms of the sample required to satisfy precision constraints. This is una?ordable in practical situations, where the dimension of the space of the partitions can be very high. Another possible way is to explore the space of partitions with an algorithm that is particularly suitable in such situations: the genetic algorithm. The R package SamplingStrata, based on the use of a genetic algorithm, allows to determine the best strati?cation for a population frame, i.e., the one that ensures the minimum sample cost necessary to satisfy precision constraints, in a multivariate and multi-domain case.

  1. Analytical and sampling problems in primary coolant circuits of PWR-type reactors

    International Nuclear Information System (INIS)

    Illy, H.

    1980-10-01

    Details of recent analytical methods on the analysis and sampling of a PWR primary coolant are given in the order as follows: sampling and preparation; analysis of the gases dissolved in the water; monitoring of radiating substances; checking of boric acid concentration which controls the reactivity. The bibliography of this work and directions for its use are published in a separate report: KFKI-80-48 (1980). (author)

  2. Clustering problems for geochemical data

    International Nuclear Information System (INIS)

    Kane, V.E.; Larson, N.M.

    1977-01-01

    The Union Carbide Corporation, Nuclear Division, Uranium Resource Evaluation Project uses a two-stage sampling program to identify potential uranium districts. Cluster analysis techniques are used in locating high density sampling areas as well as in identifying potential uranium districts. Problems are considered involving the analysis of multivariate censored data, laboratory measurement error, and data standardization

  3. A Mathematical Optimization Problem in Bioinformatics

    Science.gov (United States)

    Heyer, Laurie J.

    2008-01-01

    This article describes the sequence alignment problem in bioinformatics. Through examples, we formulate sequence alignment as an optimization problem and show how to compute the optimal alignment with dynamic programming. The examples and sample exercises have been used by the author in a specialized course in bioinformatics, but could be adapted…

  4. Variants of Callous-Unemotional Conduct Problems in a Community Sample of Adolescents

    Science.gov (United States)

    Fanti, Kostas A.; Demetriou, Chara A.; Kimonis, Eva R.

    2013-01-01

    Callous-unemotional traits are believed to be a childhood precursor to psychopathy, and among youth with conduct problems they designate those showing a particularly severe, stable, and aggressive pattern of antisocial behavior. Youth with callous-unemotional traits are a heterogeneous population and, analogous to adults with psychopathy, research…

  5. Attention deficit hyperactivity disorder, other mental health problems, substance use, and driving: examination of a population-based, representative canadian sample.

    Science.gov (United States)

    Vingilis, Evelyn; Mann, Robert E; Erickson, Patricia; Toplak, Maggie; Kolla, Nathan J; Seeley, Jane; Jain, Umesh

    2014-01-01

    The purpose of this study is to examine the relationships among self-reported screening measures of attention deficit hyperactivity disorder (ADHD), other psychiatric problems, and driving-related outcomes in a provincially representative sample of adults 18 years and older living in the province of Ontario, Canada. The study examined the results of the Centre for Addictions and Mental Health (CAMH) Ontario Monitor, an ongoing repeated cross-sectional telephone survey of Ontario adults over a 2-year period. Measures included ADHD measures (Adult ADHD Self-Report Scale-V1.1 [ASRS-V1.1], previous ADHD diagnosis, ADHD medication use); psychiatric distress measures (General Health Questionnaire [GHQ12], use of pain, anxiety, and depression medication); antisocial behavior measure (The Antisocial Personality Disorder Scale from the Mini-International Neuropsychiatric Interview [APD]); substance use and abuse measures (alcohol, cannabis, and cocaine), Alcohol Use Disorders Identification Test (AUDIT), Alcohol, Smoking and Substance Involvement Screening Test (ASSIST), driving-related outcomes (driving after drinking, driving after cannabis use, street racing, collisions in past year), and sociodemographics (gender, age, vehicle-kilometers traveled). A total of 4,014 Ontario residents were sampled, of which 3,485 reported having a valid driver's license. Overall, 3.22% screened positive for ADHD symptoms on the ASRS-V1.1 screening tool. A greater percentage of those who screened positive were younger, reported previous ADHD diagnosis and medication use, distress, antisocial behavior, anti-anxiety and antidepressant medication use, substance use, and social problems compared to those who screened negative. However, there were no statistically significant differences between those who screened positive or negative for ADHD symptoms on self-reported driving after having 2 or more drinks in the previous hour; within an hour of using cannabis, marijuana, or hash; or in a

  6. Monte Carlo stratified source-sampling

    International Nuclear Information System (INIS)

    Blomquist, R.N.; Gelbard, E.M.

    1997-01-01

    In 1995, at a conference on criticality safety, a special session was devoted to the Monte Carlo open-quotes eigenvalue of the worldclose quotes problem. Argonne presented a paper, at that session, in which the anomalies originally observed in that problem were reproduced in a much simplified model-problem configuration, and removed by a version of stratified source-sampling. The original test-problem was treated by a special code designed specifically for that purpose. Recently ANL started work on a method for dealing with more realistic eigenvalue of the world configurations, and has been incorporating this method into VIM. The original method has been modified to take into account real-world statistical noise sources not included in the model problem. This paper constitutes a status report on work still in progress

  7. A Research On Perceptions About Management Problems of Professional Accountants

    Directory of Open Access Journals (Sweden)

    Nurettin İBRAHİMOĞLU

    2014-12-01

    Full Text Available The aim of this study is to investigate the perception of administrative problems of professional accountants and to bring some solutions to their problems. The study was attended by 304 members of the accounting profession (N=304. The sample of this study was generated from the professional accountants registered to the Chamber of Gaziantep Public Accountants and Financial Advisers in Gaziantep region. Literature sources related to this problem was overviewed and some broad information about the sample and study was presented. We employed factor analysis to analyze the data. The perception of administrative problems of the accounting professionals are discussed by three factors which can be classified as follow; occupational problems, health problems, and training – communication problems. The hypotheses of this study was divided to groups and was tested by Mann - Whitney U test which is a non-parametric method alternative to t-test. According to findings of this study the most important problems of the professional accountants is classified as follow; the costumer, customer (taxpayers relationship problems, unethical request of the customers, stressful working conditions and it also found that the professional accountants with in this sample does not meet all demands of the customers

  8. Psychiatric Symptoms in Children with Gross Motor Problems

    Science.gov (United States)

    Emck, Claudia; Bosscher, Ruud J.; van Wieringen, Piet C. W.; Doreleijers, Theo; Beek, Peter J.

    2012-01-01

    Children with psychiatric disorders often demonstrate gross motor problems. This study investigates if the reverse also holds true by assessing psychiatric symptoms present in children with gross motor problems. Emotional, behavioral, and autism spectrum disorders (ASD), as well as psychosocial problems, were assessed in a sample of 40 children…

  9. Compressive sampling of polynomial chaos expansions: Convergence analysis and sampling strategies

    International Nuclear Information System (INIS)

    Hampton, Jerrad; Doostan, Alireza

    2015-01-01

    Sampling orthogonal polynomial bases via Monte Carlo is of interest for uncertainty quantification of models with random inputs, using Polynomial Chaos (PC) expansions. It is known that bounding a probabilistic parameter, referred to as coherence, yields a bound on the number of samples necessary to identify coefficients in a sparse PC expansion via solution to an ℓ 1 -minimization problem. Utilizing results for orthogonal polynomials, we bound the coherence parameter for polynomials of Hermite and Legendre type under their respective natural sampling distribution. In both polynomial bases we identify an importance sampling distribution which yields a bound with weaker dependence on the order of the approximation. For more general orthonormal bases, we propose the coherence-optimal sampling: a Markov Chain Monte Carlo sampling, which directly uses the basis functions under consideration to achieve a statistical optimality among all sampling schemes with identical support. We demonstrate these different sampling strategies numerically in both high-order and high-dimensional, manufactured PC expansions. In addition, the quality of each sampling method is compared in the identification of solutions to two differential equations, one with a high-dimensional random input and the other with a high-order PC expansion. In both cases, the coherence-optimal sampling scheme leads to similar or considerably improved accuracy

  10. Compressive sampling of polynomial chaos expansions: Convergence analysis and sampling strategies

    Science.gov (United States)

    Hampton, Jerrad; Doostan, Alireza

    2015-01-01

    Sampling orthogonal polynomial bases via Monte Carlo is of interest for uncertainty quantification of models with random inputs, using Polynomial Chaos (PC) expansions. It is known that bounding a probabilistic parameter, referred to as coherence, yields a bound on the number of samples necessary to identify coefficients in a sparse PC expansion via solution to an ℓ1-minimization problem. Utilizing results for orthogonal polynomials, we bound the coherence parameter for polynomials of Hermite and Legendre type under their respective natural sampling distribution. In both polynomial bases we identify an importance sampling distribution which yields a bound with weaker dependence on the order of the approximation. For more general orthonormal bases, we propose the coherence-optimal sampling: a Markov Chain Monte Carlo sampling, which directly uses the basis functions under consideration to achieve a statistical optimality among all sampling schemes with identical support. We demonstrate these different sampling strategies numerically in both high-order and high-dimensional, manufactured PC expansions. In addition, the quality of each sampling method is compared in the identification of solutions to two differential equations, one with a high-dimensional random input and the other with a high-order PC expansion. In both cases, the coherence-optimal sampling scheme leads to similar or considerably improved accuracy.

  11. Improved mesh based photon sampling techniques for neutron activation analysis

    International Nuclear Information System (INIS)

    Relson, E.; Wilson, P. P. H.; Biondo, E. D.

    2013-01-01

    The design of fusion power systems requires analysis of neutron activation of large, complex volumes, and the resulting particles emitted from these volumes. Structured mesh-based discretization of these problems allows for improved modeling in these activation analysis problems. Finer discretization of these problems results in large computational costs, which drives the investigation of more efficient methods. Within an ad hoc subroutine of the Monte Carlo transport code MCNP, we implement sampling of voxels and photon energies for volumetric sources using the alias method. The alias method enables efficient sampling of a discrete probability distribution, and operates in 0(1) time, whereas the simpler direct discrete method requires 0(log(n)) time. By using the alias method, voxel sampling becomes a viable alternative to sampling space with the 0(1) approach of uniformly sampling the problem volume. Additionally, with voxel sampling it is straightforward to introduce biasing of volumetric sources, and we implement this biasing of voxels as an additional variance reduction technique that can be applied. We verify our implementation and compare the alias method, with and without biasing, to direct discrete sampling of voxels, and to uniform sampling. We study the behavior of source biasing in a second set of tests and find trends between improvements and source shape, material, and material density. Overall, however, the magnitude of improvements from source biasing appears to be limited. Future work will benefit from the implementation of efficient voxel sampling - particularly with conformal unstructured meshes where the uniform sampling approach cannot be applied. (authors)

  12. Failure Probability Estimation Using Asymptotic Sampling and Its Dependence upon the Selected Sampling Scheme

    Directory of Open Access Journals (Sweden)

    Martinásková Magdalena

    2017-12-01

    Full Text Available The article examines the use of Asymptotic Sampling (AS for the estimation of failure probability. The AS algorithm requires samples of multidimensional Gaussian random vectors, which may be obtained by many alternative means that influence the performance of the AS method. Several reliability problems (test functions have been selected in order to test AS with various sampling schemes: (i Monte Carlo designs; (ii LHS designs optimized using the Periodic Audze-Eglājs (PAE criterion; (iii designs prepared using Sobol’ sequences. All results are compared with the exact failure probability value.

  13. Hybrid nested sampling algorithm for Bayesian model selection applied to inverse subsurface flow problems

    KAUST Repository

    Elsheikh, Ahmed H.; Wheeler, Mary Fanett; Hoteit, Ibrahim

    2014-01-01

    A Hybrid Nested Sampling (HNS) algorithm is proposed for efficient Bayesian model calibration and prior model selection. The proposed algorithm combines, Nested Sampling (NS) algorithm, Hybrid Monte Carlo (HMC) sampling and gradient estimation using

  14. LOGISTICS OF ECOLOGICAL SAMPLING ON LARGE RIVERS

    Science.gov (United States)

    The objectives of this document are to provide an overview of the logistical problems associated with the ecological sampling of boatable rivers and to suggest solutions to those problems. It is intended to be used as a resource for individuals preparing to collect biological dat...

  15. A comparison of problem-based and traditional education on nursing students' locus of control and problem-solving skills.

    Science.gov (United States)

    Günüşen, Neslihan Partlak; Serçekuş, Pınar; Edeer, Aylin Durmaz

    2014-06-01

    The purpose of this study is to compare the locus of control and problem-solving skills of nursing students studying with the problem-based learning method with those of nursing students studying with the traditional method. This is a descriptive and comparative study. For data collection, the Problem-Solving Skills Inventory and the Locus of Control Scale were used. The study sample included 680 nursing students. It was determined that the problem-based learning method was more effective in the development of problem-solving skills and internal locus of control than was the traditional method. © 2014 NANDA International.

  16. Television and video game exposure and the development of attention problems.

    Science.gov (United States)

    Swing, Edward L; Gentile, Douglas A; Anderson, Craig A; Walsh, David A

    2010-08-01

    Television viewing has been associated with greater subsequent attention problems in children. Few studies have examined the possibility of a similar association between video games and attention problems, and none of these has used a longitudinal design. A sample of 1323 middle childhood participants were assessed during a 13-month period by parent- and child-reported television and video game exposure as well as teacher-reported attention problems. Another sample of 210 late adolescent/early adult participants provided self-reports of television exposure, video game exposure, and attention problems. Exposure to television and video games was associated with greater attention problems. The association of television and video games to attention problems in the middle childhood sample remained significant when earlier attention problems and gender were statistically controlled. The associations of screen media and attention problems were similar across media type (television or video games) and age (middle childhood or late adolescent/early adult). Viewing television and playing video games each are associated with increased subsequent attention problems in childhood. It seems that a similar association among television, video games, and attention problems exists in late adolescence and early adulthood. Research on potential risk factors for attention problems should be expanded to include video games in addition to television.

  17. Mental health problems and overweight in a nationally representative sample of adolescents: effects of race and ethnicity.

    Science.gov (United States)

    BeLue, Rhonda; Francis, Lori Ann; Colaco, Brendon

    2009-02-01

    In this study we examined the relation between mental health problems and weight in a population-based study of youth aged 12 to 17 years and whether the association between mental health problems and weight is moderated by race and ethnicity. We used 2003 National Survey on Children's Health data. Logistic regression was used to arrive at adjusted odds ratios showing the relation between BMI and mental health problems. Compared with their nonoverweight counterparts, both white and Hispanic youth who were overweight were significantly more likely to report depression or anxiety, feelings of worthlessness or inferiority, behavior problems, and bullying of others. Odds ratios relating mental health problems and BMI in black subjects were not statistically significant except for physician diagnosis of depression. Our results suggest that, when addressing youth overweight status, mental health problems also need to be addressed. Given that the relationship between mental health problems and youth overweight differs according to race/ethnic group, public health programs that target overweight youth should be cognizant of potential comorbid mental health problems and that race/ethnicity may play a role in the relationship between mental health and overweight status.

  18. Consensus of heterogeneous multi-agent systems based on sampled data with a small sampling delay

    International Nuclear Information System (INIS)

    Wang Na; Wu Zhi-Hai; Peng Li

    2014-01-01

    In this paper, consensus problems of heterogeneous multi-agent systems based on sampled data with a small sampling delay are considered. First, a consensus protocol based on sampled data with a small sampling delay for heterogeneous multi-agent systems is proposed. Then, the algebra graph theory, the matrix method, the stability theory of linear systems, and some other techniques are employed to derive the necessary and sufficient conditions guaranteeing heterogeneous multi-agent systems to asymptotically achieve the stationary consensus. Finally, simulations are performed to demonstrate the correctness of the theoretical results. (interdisciplinary physics and related areas of science and technology)

  19. Socializing problems and low self-esteem enhance interpersonal models of eating disorders: Evidence from a clinical sample.

    Science.gov (United States)

    Raykos, Bronwyn C; McEvoy, Peter M; Fursland, Anthea

    2017-09-01

    The present study evaluated the relative clinical validity of two interpersonal models of the maintenance of eating disorders, IPT-ED (Rieger et al., ) and the interpersonal model of binge eating (Wilfley, MacKenzie, Welch, Ayres, & Weissman, ; Wilfley, Pike, & Striegel-Moore, ). While both models propose an indirect relationship between interpersonal problems and eating disorder symptoms via negative affect, IPT-ED specifies negative social evaluation as the key interpersonal problem, and places greater emphasis on the role of low self-esteem as an intermediate variable between negative social evaluation and eating pathology. Treatment-seeking individuals (N = 306) with a diagnosed eating disorder completed measures of socializing problems, generic interpersonal problems, self-esteem, eating disorder symptoms, and negative affect (depression and anxiety). Structural equation models were run for both models. Consistent with IPT-ED, a significant indirect pathway was found from socializing problems to eating disorder symptoms via low self-esteem and anxiety symptoms. There was also a direct pathway from low self-esteem to eating disorder symptoms. Using a socializing problems factor in the model resulted in a significantly better fit than a generic interpersonal problems factor. Inconsistent with both interpersonal models, the direct pathway from socializing problems to eating disorder symptoms was not supported. Interpersonal models that included self-esteem and focused on socializing problems (rather than generic interpersonal problems) explained more variance in eating disorder symptoms. Future experimental, prospective, and treatment studies are required to strengthen the case that these pathways are causal. © 2017 Wiley Periodicals, Inc.

  20. Request for wood samples

    NARCIS (Netherlands)

    NN,

    1977-01-01

    In recent years the wood collection at the Rijksherbarium was greatly expanded following a renewed interest in wood anatomy as an aid for solving classification problems. Staff members of the Rijksherbarium added to the collection by taking interesting wood samples with them from their expeditions

  1. Parentification, Stress, and Problem Behavior of Adolescents who have a Parent with Mental Health Problems.

    Science.gov (United States)

    Van Loon, Linda M A; Van de Ven, Monique O M; Van Doesum, Karin T M; Hosman, Clemens M H; Witteman, Cilia L M

    2017-03-01

    When adolescents live with a parent with mental illness, they often partly take over the parental role. Little is known about the consequences of this so-called parentification on the adolescents' internalizing and externalizing problems. This survey study examined this effect cross-sectionally and longitudinally in a sample of 118 adolescents living with a parent suffering from mental health problems. In addition, the study examined a possible indirect effect via perceived stress. Path analyses were used to examine the direct associations between parentification and problem behavior as well as the indirect relations via perceived stress. The results showed that parentification was associated with both internalizing and externalizing problems cross-sectionally, but it predicted only internalizing problems 1 year later. An indirect effect of parentification on adolescent internalizing and externalizing problems via perceived stress was found, albeit only cross-sectionally. These findings imply that parentification can be stressful for adolescents who live with a parent with mental health problems, and that a greater awareness of parentification is needed to prevent adolescents from developing internalizing problems. © 2015 Family Process Institute.

  2. Laboratory Detective Work Identifies a Mishandling Problem in Sample Aliquoting

    OpenAIRE

    Zhu, Claire; Pinsky, Paul; Huang, Wen-Yi; Purdue, Mark

    2014-01-01

    Data from a recent ovarian cancer biomarker study using serum aliquots from the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial Biorepository showed that CA125II concentrations in these aliquots were significantly lower than those previously measured in the same subjects from the same blood draw. We designed an experiment to investigate whether samples used in the study (reference study) were compromised during the aliquoting process. We measured CA125II in the “sister” ...

  3. Apparatus for freeze drying of biologic and sediment samples

    International Nuclear Information System (INIS)

    Anon.

    1978-01-01

    Freeze drying to obtain water from individual samples, though not complicated, usually requires considerable effort to maintain the cold traps on a 24-hr basis. In addition, the transfer of a sample from sample containers to freeze-dry flasks is usually made with some risk of contamination to the sample. If samples are large, 300 g to 600 g, usually several days are required to dry the samples. The use of an unattended system greatly improves personnel and drying efficiency. Commercial freeze dryers are not readily applicable to the problems of collecting water from individual samples, and lab-designed collectors required sample transfer and continual replenishment of the dry ice. A freeze-dry apparatus for collecting water from individual sediment and/or biological samples was constructed to determine the tritium concentrations in fish for dose calcaluations and the tritium distribution in sediment cores for water movement studies. The freeze, dry apparatus, which can handle eight samples simultaneously and conveniently, is set up for unattended 24-hr operation and is designed to avoid sample transfer problems

  4. UMAPRM: Uniformly sampling the medial axis

    KAUST Repository

    Yeh, Hsin-Yi Cindy

    2014-05-01

    © 2014 IEEE. Maintaining clearance, or distance from obstacles, is a vital component of successful motion planning algorithms. Maintaining high clearance often creates safer paths for robots. Contemporary sampling-based planning algorithms That utilize The medial axis, or The set of all points equidistant To Two or more obstacles, produce higher clearance paths. However, They are biased heavily Toward certain portions of The medial axis, sometimes ignoring parts critical To planning, e.g., specific Types of narrow passages. We introduce Uniform Medial Axis Probabilistic RoadMap (UMAPRM), a novel planning variant That generates samples uniformly on The medial axis of The free portion of Cspace. We Theoretically analyze The distribution generated by UMAPRM and show its uniformity. Our results show That UMAPRM\\'s distribution of samples along The medial axis is not only uniform but also preferable To other medial axis samplers in certain planning problems. We demonstrate That UMAPRM has negligible computational overhead over other sampling Techniques and can solve problems The others could not, e.g., a bug Trap. Finally, we demonstrate UMAPRM successfully generates higher clearance paths in The examples.

  5. Identifying indicators of harmful and problem gambling in a Canadian sample through receiver operating characteristic analysis.

    Science.gov (United States)

    Quilty, Lena C; Avila Murati, Daniela; Bagby, R Michael

    2014-03-01

    Many gamblers would prefer to reduce gambling on their own rather than to adopt an abstinence approach within the context of a gambling treatment program. Yet responsible gambling guidelines lack quantifiable markers to guide gamblers in wagering safely. To address these issues, the current investigation implemented receiver operating characteristic (ROC) analysis to identify behavioral indicators of harmful and problem gambling. Gambling involvement was assessed in 503 participants (275 psychiatric outpatients and 228 community gamblers) with the Canadian Problem Gambling Index. Overall gambling frequency, duration, and expenditure were able to distinguish harmful and problematic gambling at a moderate level. Indicators of harmful gambling were generated for engagement in specific gambling activities: frequency of tickets and casino; duration of bingo, casino, and investments; and expenditures on bingo, casino, sports betting, games of skill, and investments. Indicators of problem gambling were similarly produced for frequency of tickets and casino, and expenditures on bingo, casino, games of skill, and investments. Logistic regression analyses revealed that overall gambling frequency uniquely predicted the presence of harmful and problem gambling. Furthermore, frequency indicators for tickets and casino uniquely predicted the presence of both harmful and problem gambling. Together, these findings contribute to the development of an empirically based method enabling the minimization of harmful or problem gambling through self-control rather than abstinence.

  6. Enhanced conformational sampling using enveloping distribution sampling.

    Science.gov (United States)

    Lin, Zhixiong; van Gunsteren, Wilfred F

    2013-10-14

    To lessen the problem of insufficient conformational sampling in biomolecular simulations is still a major challenge in computational biochemistry. In this article, an application of the method of enveloping distribution sampling (EDS) is proposed that addresses this challenge and its sampling efficiency is demonstrated in simulations of a hexa-β-peptide whose conformational equilibrium encompasses two different helical folds, i.e., a right-handed 2.7(10∕12)-helix and a left-handed 3(14)-helix, separated by a high energy barrier. Standard MD simulations of this peptide using the GROMOS 53A6 force field did not reach convergence of the free enthalpy difference between the two helices even after 500 ns of simulation time. The use of soft-core non-bonded interactions in the centre of the peptide did enhance the number of transitions between the helices, but at the same time led to neglect of relevant helical configurations. In the simulations of a two-state EDS reference Hamiltonian that envelops both the physical peptide and the soft-core peptide, sampling of the conformational space of the physical peptide ensures that physically relevant conformations can be visited, and sampling of the conformational space of the soft-core peptide helps to enhance the transitions between the two helices. The EDS simulations sampled many more transitions between the two helices and showed much faster convergence of the relative free enthalpy of the two helices compared with the standard MD simulations with only a slightly larger computational effort to determine optimized EDS parameters. Combined with various methods to smoothen the potential energy surface, the proposed EDS application will be a powerful technique to enhance the sampling efficiency in biomolecular simulations.

  7. On Using a Pilot Sample Variance for Sample Size Determination in the Detection of Differences between Two Means: Power Consideration

    Science.gov (United States)

    Shieh, Gwowen

    2013-01-01

    The a priori determination of a proper sample size necessary to achieve some specified power is an important problem encountered frequently in practical studies. To establish the needed sample size for a two-sample "t" test, researchers may conduct the power analysis by specifying scientifically important values as the underlying population means…

  8. Depression and Related Problems in University Students

    Science.gov (United States)

    Field, Tiffany; Diego, Miguel; Pelaez, Martha; Deeds, Osvelia; Delgado, Jeannette

    2012-01-01

    Method: Depression and related problems were studied in a sample of 283 university students. Results: The students with high depression scores also had high scores on anxiety, intrusive thoughts, controlling intrusive thoughts and sleep disturbances scales. A stepwise regression suggested that those problems contributed to a significant proportion…

  9. Liquid scintillation: Sample preparation and counting atypical emissions

    International Nuclear Information System (INIS)

    Anon.

    1991-01-01

    Liquid scintillation sample preparation has the most published information but the least amount of definitive technical direction because the chemical and physical nature of the samples from biological investigations varies widely. This chapter discusses the following related topics: Aqueous Samples; Tissue Solubilizers; Absorption of 14 CO 2 ; Sample Combustion Methods; Heterogeneous Systems; Sample Preparation Problems (colored samples, chemiluminescence, photoluminescence, static electricity); Counting Various Types of Emitters; Counting Atypical Emissions. 2 refs., 2 figs

  10. BWIP-RANDOM-SAMPLING, Random Sample Generation for Nuclear Waste Disposal

    International Nuclear Information System (INIS)

    Sagar, B.

    1989-01-01

    1 - Description of program or function: Random samples for different distribution types are generated. Distribution types as required for performance assessment modeling of geologic nuclear waste disposal are provided. These are: - Uniform, - Log-uniform (base 10 or natural), - Normal, - Lognormal (base 10 or natural), - Exponential, - Bernoulli, - User defined continuous distribution. 2 - Method of solution: A linear congruential generator is used for uniform random numbers. A set of functions is used to transform the uniform distribution to the other distributions. Stratified, rather than random, sampling can be chosen. Truncated limits can be specified on many distributions, whose usual definition has an infinite support. 3 - Restrictions on the complexity of the problem: Generation of correlated random variables is not included

  11. Processes involved in solving mathematical problems

    Science.gov (United States)

    Shahrill, Masitah; Putri, Ratu Ilma Indra; Zulkardi, Prahmana, Rully Charitas Indra

    2018-04-01

    This study examines one of the instructional practices features utilized within the Year 8 mathematics lessons in Brunei Darussalam. The codes from the TIMSS 1999 Video Study were applied and strictly followed, and from the 183 mathematics problems recorded, there were 95 problems with a solution presented during the public segments of the video-recorded lesson sequences of the four sampled teachers. The analyses involved firstly, identifying the processes related to mathematical problem statements, and secondly, examining the different processes used in solving the mathematical problems for each problem publicly completed during the lessons. The findings revealed that for three of the teachers, their problem statements coded as `using procedures' ranged from 64% to 83%, while the remaining teacher had 40% of his problem statements coded as `making connections.' The processes used when solving the problems were mainly `using procedures', and none of the problems were coded as `giving results only'. Furthermore, all four teachers made use of making the relevant connections in solving the problems given to their respective students.

  12. Quota sampling in internet research: practical issues.

    Science.gov (United States)

    Im, Eun-Ok; Chee, Wonshik

    2011-07-01

    Quota sampling has been suggested as a potentially good method for Internet-based research and has been used by several researchers working with Internet samples. However, very little is known about the issues or concerns in using a quota sampling method in Internet research. The purpose of this article was to present the practical issues using quota sampling in an Internet-based study. During the Internet study, the research team recorded all recruitment issues that arose and made written notes indicating the possible reasons for the problems. In addition, biweekly team discussions were conducted for which written records were kept. Overall, quota sampling was effective in ensuring that an adequate number of midlife women were recruited from the targeted ethnic groups. However, during the study process, we encountered the following practical issues using quota sampling: (1) difficulty reaching out to women in lower socioeconomic classes, (2) difficulty ensuring authenticity of participants' identities, (3) participants giving inconsistent answers for the screening questions versus the Internet survey questions, (4) potential problems with a question on socioeconomic status, (5) resentment toward the research project and/or researchers because of rejection, and (6) a longer time and more expense than anticipated.

  13. Robust online tracking via adaptive samples selection with saliency detection

    Science.gov (United States)

    Yan, Jia; Chen, Xi; Zhu, QiuPing

    2013-12-01

    Online tracking has shown to be successful in tracking of previously unknown objects. However, there are two important factors which lead to drift problem of online tracking, the one is how to select the exact labeled samples even when the target locations are inaccurate, and the other is how to handle the confusors which have similar features with the target. In this article, we propose a robust online tracking algorithm with adaptive samples selection based on saliency detection to overcome the drift problem. To deal with the problem of degrading the classifiers using mis-aligned samples, we introduce the saliency detection method to our tracking problem. Saliency maps and the strong classifiers are combined to extract the most correct positive samples. Our approach employs a simple yet saliency detection algorithm based on image spectral residual analysis. Furthermore, instead of using the random patches as the negative samples, we propose a reasonable selection criterion, in which both the saliency confidence and similarity are considered with the benefits that confusors in the surrounding background are incorporated into the classifiers update process before the drift occurs. The tracking task is formulated as a binary classification via online boosting framework. Experiment results in several challenging video sequences demonstrate the accuracy and stability of our tracker.

  14. Investigative studies on water contamination in Bangladesh. Primary treatment of water samples at the sampling site

    International Nuclear Information System (INIS)

    Sera, K.; Islam, Md. Shafiqul; Takatsuji, T.; Nakamura, T.; Goto, S.; Takahashi, C.; Saitoh, Y.

    2010-01-01

    Arsenic concentration in 13 well waters, 9 pond waters, 10 agricultural waters and a coconut juice taken in Comilla district, Bangladesh, where the problem of arsenic pollution is the most severe, was investigated. High-level arsenic is detected even in the well water which has been kept drinking by the people. Relatively high arsenic concentration was detected for some pond and farm waters even though the sampling was performed just after the rainy season and the waters were expected to be highly diluted. Clear relationship was observed in elemental compositions between the pond water and the coconut juice collected at the edge of the water. These results are expected to become the basic information for evaluating the risk of individual food such as cultured fishes, shrimps and farm products, and for controlling total intakes of arsenic. In order to solve the problem of transportation of water samples internationally, a simple method of target preparation performed at the sampling site was established and its validity was confirmed. All targets were prepared at the sampling sites in this study on the basis of this method. (author)

  15. The two-model problem in rational decision making

    NARCIS (Netherlands)

    Boumans, Marcel

    2011-01-01

    A model of a decision problem frames that problem in three dimensions: sample space, target probability and information structure. Each specific model imposes a specific rational decision. As a result, different models may impose different, even contradictory, rational decisions, creating choice

  16. FEMSYN - a code system to solve multigroup diffusion theory equations using a variety of solution techniques. Part 1 : Description of code system - input and sample problems

    International Nuclear Information System (INIS)

    Jagannathan, V.

    1985-01-01

    A modular computer code system called FEMSYN has been developed to solve the multigroup diffusion theory equations. The various methods that are incorporated in FEMSYN are (i) finite difference method (FDM) (ii) finite element method (FEM) and (iii) single channel flux synthesis method (SCFS). These methods are described in detail in parts II, III and IV of the present report. In this report, a comparison of the accuracy and the speed of different methods of solution for some benchmark problems are reported. The input preparation and listing of sample input and output are included in the Appendices. The code FEMSYN has been used to solve a wide variety of reactor core problems. It can be used for both LWR and PHWR applications. (author)

  17. Principal Stratification in sample selection problems with non normal error terms

    DEFF Research Database (Denmark)

    Rocci, Roberto; Mellace, Giovanni

    The aim of the paper is to relax distributional assumptions on the error terms, often imposed in parametric sample selection models to estimate causal effects, when plausible exclusion restrictions are not available. Within the principal stratification framework, we approximate the true distribut...... an application to the Job Corps training program....

  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. Estimating Sample Size for Usability Testing

    Directory of Open Access Journals (Sweden)

    Alex Cazañas

    2017-02-01

    Full Text Available One strategy used to assure that an interface meets user requirements is to conduct usability testing. When conducting such testing one of the unknowns is sample size. Since extensive testing is costly, minimizing the number of participants can contribute greatly to successful resource management of a project. Even though a significant number of models have been proposed to estimate sample size in usability testing, there is still not consensus on the optimal size. Several studies claim that 3 to 5 users suffice to uncover 80% of problems in a software interface. However, many other studies challenge this assertion. This study analyzed data collected from the user testing of a web application to verify the rule of thumb, commonly known as the “magic number 5”. The outcomes of the analysis showed that the 5-user rule significantly underestimates the required sample size to achieve reasonable levels of problem detection.

  20. Externalizing Behavior Problems during Adolescence: An Ecological Perspective

    Science.gov (United States)

    White, Rachel; Renk, Kimberly

    2012-01-01

    Given the ramifications of difficulties related to externalizing behavior problems, the present study examined the relationships among adolescents' externalizing behavior problems, characteristics of adolescents' families, their perceived neighborhood support, and their acculturation. As part of this study, a culturally diverse sample of…

  1. Functions with disconnected spectrum sampling, interpolation, translates

    CERN Document Server

    Olevskii, Alexander M

    2016-01-01

    The classical sampling problem is to reconstruct entire functions with given spectrum S from their values on a discrete set L. From the geometric point of view, the possibility of such reconstruction is equivalent to determining for which sets L the exponential system with frequencies in L forms a frame in the space L^2(S). The book also treats the problem of interpolation of discrete functions by analytic ones with spectrum in S and the problem of completeness of discrete translates. The size and arithmetic structure of both the spectrum S and the discrete set L play a crucial role in these problems. After an elementary introduction, the authors give a new presentation of classical results due to Beurling, Kahane, and Landau. The main part of the book focuses on recent progress in the area, such as construction of universal sampling sets, high-dimensional and non-analytic phenomena. The reader will see how methods of harmonic and complex analysis interplay with various important concepts in different areas, ...

  2. Automatic coal sampling for thermoelectric power plants; some remarks on moisture

    Energy Technology Data Exchange (ETDEWEB)

    Tanzi, M.

    1983-06-01

    Some problems associated with automatic coal sampling are discussed, in particular the change in moisture content during transport to sampling station. The moisture level is reduced by crushing and air exposure. Possible solutions to the problems are outlined: reducing exposure to air; reducing the degree of pulverisation; and use of special crushing equipment.

  3. Sampling based motion planning with reachable volumes: Application to manipulators and closed chain systems

    KAUST Repository

    McMahon, Troy

    2014-09-01

    © 2014 IEEE. Reachable volumes are a geometric representation of the regions the joints of a robot can reach. They can be used to generate constraint satisfying samples for problems including complicated linkage robots (e.g. closed chains and graspers). They can also be used to assist robot operators and to help in robot design.We show that reachable volumes have an O(1) complexity in unconstrained problems as well as in many constrained problems. We also show that reachable volumes can be computed in linear time and that reachable volume samples can be generated in linear time in problems without constraints. We experimentally validate reachable volume sampling, both with and without constraints on end effectors and/or internal joints. We show that reachable volume samples are less likely to be invalid due to self-collisions, making reachable volume sampling significantly more efficient for higher dimensional problems. We also show that these samples are easier to connect than others, resulting in better connected roadmaps. We demonstrate that our method can be applied to 262-dof, multi-loop, and tree-like linkages including combinations of planar, prismatic and spherical joints. In contrast, existing methods either cannot be used for these problems or do not produce good quality solutions.

  4. Sampling based motion planning with reachable volumes: Application to manipulators and closed chain systems

    KAUST Repository

    McMahon, Troy; Thomas, Shawna; Amato, Nancy M.

    2014-01-01

    © 2014 IEEE. Reachable volumes are a geometric representation of the regions the joints of a robot can reach. They can be used to generate constraint satisfying samples for problems including complicated linkage robots (e.g. closed chains and graspers). They can also be used to assist robot operators and to help in robot design.We show that reachable volumes have an O(1) complexity in unconstrained problems as well as in many constrained problems. We also show that reachable volumes can be computed in linear time and that reachable volume samples can be generated in linear time in problems without constraints. We experimentally validate reachable volume sampling, both with and without constraints on end effectors and/or internal joints. We show that reachable volume samples are less likely to be invalid due to self-collisions, making reachable volume sampling significantly more efficient for higher dimensional problems. We also show that these samples are easier to connect than others, resulting in better connected roadmaps. We demonstrate that our method can be applied to 262-dof, multi-loop, and tree-like linkages including combinations of planar, prismatic and spherical joints. In contrast, existing methods either cannot be used for these problems or do not produce good quality solutions.

  5. Local Search Approaches in Stable Matching Problems

    Directory of Open Access Journals (Sweden)

    Toby Walsh

    2013-10-01

    Full Text Available The stable marriage (SM problem has a wide variety of practical applications, ranging from matching resident doctors to hospitals, to matching students to schools or, more generally, to any two-sided market. In the classical formulation, n men and n women express their preferences (via a strict total order over the members of the other sex. Solving an SM problem means finding a stable marriage where stability is an envy-free notion: no man and woman who are not married to each other would both prefer each other to their partners or to being single. We consider both the classical stable marriage problem and one of its useful variations (denoted SMTI (Stable Marriage with Ties and Incomplete lists where the men and women express their preferences in the form of an incomplete preference list with ties over a subset of the members of the other sex. Matchings are permitted only with people who appear in these preference lists, and we try to find a stable matching that marries as many people as possible. Whilst the SM problem is polynomial to solve, the SMTI problem is NP-hard. We propose to tackle both problems via a local search approach, which exploits properties of the problems to reduce the size of the neighborhood and to make local moves efficiently. We empirically evaluate our algorithm for SM problems by measuring its runtime behavior and its ability to sample the lattice of all possible stable marriages. We evaluate our algorithm for SMTI problems in terms of both its runtime behavior and its ability to find a maximum cardinality stable marriage. Experimental results suggest that for SM problems, the number of steps of our algorithm grows only as O(n log(n, and that it samples very well the set of all stable marriages. It is thus a fair and efficient approach to generate stable marriages. Furthermore, our approach for SMTI problems is able to solve large problems, quickly returning stable matchings of large and often optimal size, despite the

  6. Using Load Balancing to Scalably Parallelize Sampling-Based Motion Planning Algorithms

    KAUST Repository

    Fidel, Adam; Jacobs, Sam Ade; Sharma, Shishir; Amato, Nancy M.; Rauchwerger, Lawrence

    2014-01-01

    Motion planning, which is the problem of computing feasible paths in an environment for a movable object, has applications in many domains ranging from robotics, to intelligent CAD, to protein folding. The best methods for solving this PSPACE-hard problem are so-called sampling-based planners. Recent work introduced uniform spatial subdivision techniques for parallelizing sampling-based motion planning algorithms that scaled well. However, such methods are prone to load imbalance, as planning time depends on region characteristics and, for most problems, the heterogeneity of the sub problems increases as the number of processors increases. In this work, we introduce two techniques to address load imbalance in the parallelization of sampling-based motion planning algorithms: an adaptive work stealing approach and bulk-synchronous redistribution. We show that applying these techniques to representatives of the two major classes of parallel sampling-based motion planning algorithms, probabilistic roadmaps and rapidly-exploring random trees, results in a more scalable and load-balanced computation on more than 3,000 cores. © 2014 IEEE.

  7. Using Load Balancing to Scalably Parallelize Sampling-Based Motion Planning Algorithms

    KAUST Repository

    Fidel, Adam

    2014-05-01

    Motion planning, which is the problem of computing feasible paths in an environment for a movable object, has applications in many domains ranging from robotics, to intelligent CAD, to protein folding. The best methods for solving this PSPACE-hard problem are so-called sampling-based planners. Recent work introduced uniform spatial subdivision techniques for parallelizing sampling-based motion planning algorithms that scaled well. However, such methods are prone to load imbalance, as planning time depends on region characteristics and, for most problems, the heterogeneity of the sub problems increases as the number of processors increases. In this work, we introduce two techniques to address load imbalance in the parallelization of sampling-based motion planning algorithms: an adaptive work stealing approach and bulk-synchronous redistribution. We show that applying these techniques to representatives of the two major classes of parallel sampling-based motion planning algorithms, probabilistic roadmaps and rapidly-exploring random trees, results in a more scalable and load-balanced computation on more than 3,000 cores. © 2014 IEEE.

  8. The effect of problem posing and problem solving with realistic mathematics education approach to the conceptual understanding and adaptive reasoning

    Science.gov (United States)

    Mahendra, Rengga; Slamet, Isnandar; Budiyono

    2017-12-01

    One of the difficulties of students in learning mathematics is on the subject of geometry that requires students to understand abstract things. The aim of this research is to determine the effect of learning model Problem Posing and Problem Solving with Realistic Mathematics Education Approach to conceptual understanding and students' adaptive reasoning in learning mathematics. This research uses a kind of quasi experimental research. The population of this research is all seventh grade students of Junior High School 1 Jaten, Indonesia. The sample was taken using stratified cluster random sampling technique. The test of the research hypothesis was analyzed by using t-test. The results of this study indicate that the model of Problem Posing learning with Realistic Mathematics Education Approach can improve students' conceptual understanding significantly in mathematics learning. In addition tu, the results also showed that the model of Problem Solving learning with Realistic Mathematics Education Approach can improve students' adaptive reasoning significantly in learning mathematics. Therefore, the model of Problem Posing and Problem Solving learning with Realistic Mathematics Education Approach is appropriately applied in mathematics learning especially on the subject of geometry so as to improve conceptual understanding and students' adaptive reasoning. Furthermore, the impact can improve student achievement.

  9. Personality Traits, Sexual Problems, and Sexual Orientation: An Empirical Study.

    Science.gov (United States)

    Peixoto, Maria Manuela; Nobre, Pedro

    2016-01-01

    Personality traits, namely neuroticism, have been suggested as vulnerability factors for the development and maintenance of sexual dysfunction in heterosexual samples. However, no evidence was found regarding homosexual samples. This study aimed to analyze the differences on personality traits between heterosexual and homosexual men and women with and without sexual problems. Participants were 285 individuals (142 men, 143 women) who completed a web-based survey. Participants answered the NEO Five-Factor Inventory, the Brief Symptomatology Inventory, and questions regarding sexual problems. The groups of men and women with and without sexual problems were matched for sociodemographic variables. A 2 (Group) × 2 (Sexual Orientation) multivariate analysis of covariance was conducted separately for each gender. Results indicated a significant main effect for group and for sexual orientation in male and female samples. Men with sexual problems scored higher on neuroticism, whereas women with sexual problems scored higher on neuroticism and lower on extraversion when compared with healthy controls, regardless of sexual orientation. In addition, gay men scored higher on neuroticism and lesbian women scored higher on conscientiousness compared with the heterosexual groups. The present findings emphasize the central role of neuroticism on sexual problems in both men and women regardless of sexual orientation.

  10. Fractal measures in a deep penetration problem

    International Nuclear Information System (INIS)

    Murthy, K.P.N.; Indira, R.; John, T.M.

    1993-01-01

    In the Monte Carlo simulation of a deep penetration problem the parameter, say b in the importance function must be assigned a value b' such that variance is minimum. If b b' the sample mean is still not reliable; but the sample fluctuations would be small and misleading, though the actual fluctuations are quite large. This is because the distribution of transmission has a tail which becomes prominent when b > b'. Considering a model deep penetration problem, and employing exact enumeration techniques, it is shown that in the limit of large biasing the long tailed distribution to the transmission is multifractal. (author). 5 refs., 3 figs

  11. Students’ difficulties in probabilistic problem-solving

    Science.gov (United States)

    Arum, D. P.; Kusmayadi, T. A.; Pramudya, I.

    2018-03-01

    There are many errors can be identified when students solving mathematics problems, particularly in solving the probabilistic problem. This present study aims to investigate students’ difficulties in solving the probabilistic problem. It focuses on analyzing and describing students errors during solving the problem. This research used the qualitative method with case study strategy. The subjects in this research involve ten students of 9th grade that were selected by purposive sampling. Data in this research involve students’ probabilistic problem-solving result and recorded interview regarding students’ difficulties in solving the problem. Those data were analyzed descriptively using Miles and Huberman steps. The results show that students have difficulties in solving the probabilistic problem and can be divided into three categories. First difficulties relate to students’ difficulties in understanding the probabilistic problem. Second, students’ difficulties in choosing and using appropriate strategies for solving the problem. Third, students’ difficulties with the computational process in solving the problem. Based on the result seems that students still have difficulties in solving the probabilistic problem. It means that students have not able to use their knowledge and ability for responding probabilistic problem yet. Therefore, it is important for mathematics teachers to plan probabilistic learning which could optimize students probabilistic thinking ability.

  12. Sampling Realistic Protein Conformations Using Local Structural Bias

    DEFF Research Database (Denmark)

    Hamelryck, Thomas Wim; Kent, John T.; Krogh, A.

    2006-01-01

    The prediction of protein structure from sequence remains a major unsolved problem in biology. The most successful protein structure prediction methods make use of a divide-and-conquer strategy to attack the problem: a conformational sampling method generates plausible candidate structures, which...... are subsequently accepted or rejected using an energy function. Conceptually, this often corresponds to separating local structural bias from the long-range interactions that stabilize the compact, native state. However, sampling protein conformations that are compatible with the local structural bias encoded...... in a given protein sequence is a long-standing open problem, especially in continuous space. We describe an elegant and mathematically rigorous method to do this, and show that it readily generates native-like protein conformations simply by enforcing compactness. Our results have far-reaching implications...

  13. Does Preschool Self-Regulation Predict Later Behavior Problems in General or Specific Problem Behaviors?

    Science.gov (United States)

    Lonigan, Christopher J; Spiegel, Jamie A; Goodrich, J Marc; Morris, Brittany M; Osborne, Colleen M; Lerner, Matthew D; Phillips, Beth M

    2017-11-01

    Findings from prior research have consistently indicated significant associations between self-regulation and externalizing behaviors. Significant associations have also been reported between children's language skills and both externalizing behaviors and self-regulation. Few studies to date, however, have examined these relations longitudinally, simultaneously, or with respect to unique clusters of externalizing problems. The current study examined the influence of preschool self-regulation on general and specific externalizing behavior problems in early elementary school and whether these relations were independent of associations between language, self-regulation, and externalizing behaviors in a sample of 815 children (44% female). Additionally, given a general pattern of sex differences in the presentations of externalizing behavior problems, self-regulation, and language skills, sex differences for these associations were examined. Results indicated unique relations of preschool self-regulation and language with both general externalizing behavior problems and specific problems of inattention. In general, self-regulation was a stronger longitudinal correlate of externalizing behavior for boys than it was for girls, and language was a stronger longitudinal predictor of hyperactive/impulsive behavior for girls than it was for boys.

  14. Toxaphene: a challenging analytical problem

    NARCIS (Netherlands)

    de Geus, H.J.; Wester, P.G.; Schelvis, A.; de Boer, J.; Brinkman, U.A.T.

    2000-01-01

    The analysis of toxaphene, a highly complex mixture of chlorinated bornanes, bornenes and camphenes, is a challenging problem, especially as individual congeners are present at trace levels in biota and other relevant samples. The complicated nomenclature of the compounds of interest is briefly

  15. A Cognitive Analysis of Students’ Mathematical Problem Solving Ability on Geometry

    Science.gov (United States)

    Rusyda, N. A.; Kusnandi, K.; Suhendra, S.

    2017-09-01

    The purpose of this research is to analyze of mathematical problem solving ability of students in one of secondary school on geometry. This research was conducted by using quantitative approach with descriptive method. Population in this research was all students of that school and the sample was twenty five students that was chosen by purposive sampling technique. Data of mathematical problem solving were collected through essay test. The results showed the percentage of achievement of mathematical problem solving indicators of students were: 1) solve closed mathematical problems with context in math was 50%; 2) solve the closed mathematical problems with the context beyond mathematics was 24%; 3) solving open mathematical problems with contexts in mathematics was 35%; And 4) solving open mathematical problems with contexts outside mathematics was 44%. Based on the percentage, it can be concluded that the level of achievement of mathematical problem solving ability in geometry still low. This is because students are not used to solving problems that measure mathematical problem solving ability, weaknesses remember previous knowledge, and lack of problem solving framework. So the students’ ability of mathematical problems solving need to be improved with implement appropriate learning strategy.

  16. Adjustment problems and residential care environment

    OpenAIRE

    Jan Sebastian Novotný

    2015-01-01

    Problem: Residential care environment represents a specific social space that is associated with a number of negative consequences, covering most aspects of children and youth functioning. The paper analyzes of the presence of adjustment problems among adolescents from institutional care environment and compares this results with a population of adolescents who grew up in a family. Methods: The sample consisted of two groups of adolescents. The first group included 285 adolescents currently g...

  17. A simple approach to power and sample size calculations in logistic regression and Cox regression models.

    Science.gov (United States)

    Vaeth, Michael; Skovlund, Eva

    2004-06-15

    For a given regression problem it is possible to identify a suitably defined equivalent two-sample problem such that the power or sample size obtained for the two-sample problem also applies to the regression problem. For a standard linear regression model the equivalent two-sample problem is easily identified, but for generalized linear models and for Cox regression models the situation is more complicated. An approximately equivalent two-sample problem may, however, also be identified here. In particular, we show that for logistic regression and Cox regression models the equivalent two-sample problem is obtained by selecting two equally sized samples for which the parameters differ by a value equal to the slope times twice the standard deviation of the independent variable and further requiring that the overall expected number of events is unchanged. In a simulation study we examine the validity of this approach to power calculations in logistic regression and Cox regression models. Several different covariate distributions are considered for selected values of the overall response probability and a range of alternatives. For the Cox regression model we consider both constant and non-constant hazard rates. The results show that in general the approach is remarkably accurate even in relatively small samples. Some discrepancies are, however, found in small samples with few events and a highly skewed covariate distribution. Comparison with results based on alternative methods for logistic regression models with a single continuous covariate indicates that the proposed method is at least as good as its competitors. The method is easy to implement and therefore provides a simple way to extend the range of problems that can be covered by the usual formulas for power and sample size determination. Copyright 2004 John Wiley & Sons, Ltd.

  18. Enhancing students’ mathematical problem posing skill through writing in performance tasks strategy

    Science.gov (United States)

    Kadir; Adelina, R.; Fatma, M.

    2018-01-01

    Many researchers have studied the Writing in Performance Task (WiPT) strategy in learning, but only a few paid attention on its relation to the problem-posing skill in mathematics. The problem-posing skill in mathematics covers problem reformulation, reconstruction, and imitation. The purpose of the present study was to examine the effect of WiPT strategy on students’ mathematical problem-posing skill. The research was conducted at a Public Junior Secondary School in Tangerang Selatan. It used a quasi-experimental method with randomized control group post-test. The samples were 64 students consists of 32 students of the experiment group and 32 students of the control. A cluster random sampling technique was used for sampling. The research data were obtained by testing. The research shows that the problem-posing skill of students taught by WiPT strategy is higher than students taught by a conventional strategy. The research concludes that the WiPT strategy is more effective in enhancing the students’ mathematical problem-posing skill compared to the conventional strategy.

  19. Intersecting Identities and Substance Use Problems: Sexual Orientation, Gender, Race, and Lifetime Substance Use Problems

    Science.gov (United States)

    Mereish, Ethan H.; Bradford, Judith B.

    2014-01-01

    Objective: Research has documented that sexual minorities are at greater risk for substance use than heterosexuals. However, there are limited studies and mixed findings when investigating these health disparities among racial and ethnic minority samples. We used an intersectionality framework to examine disparities in lifetime substance use problems between heterosexual and sexual minority men and women and within sexual minority groups among a racially diverse sample. Method: A nonprobability sample of heterosexual (n = 1,091) and sexual minority (n = 1,465) patients from an urban community health center ranged in age from 18 to 72 years. Participants completed a brief patient survey and reported demographic information and history of lifetime substance use problems. Logistic regressions analyses were used to examine interactions between and among sexual orientation, gender, and race. Results: We found a significant three-way interaction among sexual orientation, gender, and race. Sexual minorities had a greater risk of self-reported lifetime substance use problems than heterosexuals, with nuanced gender and racial differences. Of greatest note, sexual minority women of color had greater risks than heterosexual women of color and than White sexual minority women. Sexual minority men of color did not differ in their risk when compared with heterosexual men of color, and they had lower risk than White sexual minority men. Conclusions: The results of this study demonstrate that an intersectionality framework is crucial to clearly identify lifetime substance use disparities between racially diverse sexual minority and heterosexual men and women. Future research, treatment, and policy should use intersectionality approaches when addressing substance use disparities. PMID:24411810

  20. Boson sampling with integrated optical circuits

    International Nuclear Information System (INIS)

    Bentivegna, M.

    2014-01-01

    Simulating the evolution of non-interacting bosons through a linear transformation acting on the system’s Fock state is strongly believed to be hard for a classical computer. This is commonly known as the Boson Sampling problem, and has recently got attention as the first possible way to demonstrate the superior computational power of quantum devices over classical ones. In this paper we describe the quantum optics approach to this problem, highlighting the role of integrated optical circuits.

  1. Gambling Problems in the General Danish Population

    DEFF Research Database (Denmark)

    Harrison, Glenn W.; Jessen, Lasse J.; Lau, Morten

    We compare several popular survey instruments for measuring gambling behavior and gambling propensity to assess if they differ in their classification of individuals in the general adult Danish population. We also examine correlations with standard survey instruments for alcohol use, anxiety......, depression and impulsivity. A feature of our design is that nobody was excluded on the basis of their response to a “trigger,” “gateway” or “diagnostic item” question about previous gambling history. Our sample consists of 8,405 adult Danes. We administered the Focal Adult Gambling Screen to all subjects...... and estimate prevalence of gambling problems using sample weights and controlling for sample selection. We find that 95.4% of the population has no detectable risk, 2.9% has an early risk, 0.8% has an intermediate risk, 0.7% has an advanced risk, and 0.2% can be classified as problem gamblers...

  2. Optimal time points sampling in pathway modelling.

    Science.gov (United States)

    Hu, Shiyan

    2004-01-01

    Modelling cellular dynamics based on experimental data is at the heart of system biology. Considerable progress has been made to dynamic pathway modelling as well as the related parameter estimation. However, few of them gives consideration for the issue of optimal sampling time selection for parameter estimation. Time course experiments in molecular biology rarely produce large and accurate data sets and the experiments involved are usually time consuming and expensive. Therefore, to approximate parameters for models with only few available sampling data is of significant practical value. For signal transduction, the sampling intervals are usually not evenly distributed and are based on heuristics. In the paper, we investigate an approach to guide the process of selecting time points in an optimal way to minimize the variance of parameter estimates. In the method, we first formulate the problem to a nonlinear constrained optimization problem by maximum likelihood estimation. We then modify and apply a quantum-inspired evolutionary algorithm, which combines the advantages of both quantum computing and evolutionary computing, to solve the optimization problem. The new algorithm does not suffer from the morass of selecting good initial values and being stuck into local optimum as usually accompanied with the conventional numerical optimization techniques. The simulation results indicate the soundness of the new method.

  3. Using machine learning to accelerate sampling-based inversion

    Science.gov (United States)

    Valentine, A. P.; Sambridge, M.

    2017-12-01

    In most cases, a complete solution to a geophysical inverse problem (including robust understanding of the uncertainties associated with the result) requires a sampling-based approach. However, the computational burden is high, and proves intractable for many problems of interest. There is therefore considerable value in developing techniques that can accelerate sampling procedures.The main computational cost lies in evaluation of the forward operator (e.g. calculation of synthetic seismograms) for each candidate model. Modern machine learning techniques-such as Gaussian Processes-offer a route for constructing a computationally-cheap approximation to this calculation, which can replace the accurate solution during sampling. Importantly, the accuracy of the approximation can be refined as inversion proceeds, to ensure high-quality results.In this presentation, we describe and demonstrate this approach-which can be seen as an extension of popular current methods, such as the Neighbourhood Algorithm, and bridges the gap between prior- and posterior-sampling frameworks.

  4. Features and characteristics of problem based learning

    Directory of Open Access Journals (Sweden)

    Eser Ceker

    2016-12-01

    Full Text Available Throughout the years, there appears to be an increase in Problem Based Learning applications in education; and Problem Based Learning related research areas. The main aim of this research is to underline the fundamentals (basic elements of Problem Based Learning, investigate the dimensions of research approached to PBL oriented areas (with a look for the latest technology supported tools of Problem Based Learning. This research showed that the most researched characteristics of PBL are; teacher and student assessments on Problem Based Learning, Variety of disciplines in which Problem Based Learning strategies were tried and success evaluated, Using Problem Based Learning alone or with other strategies (Hybrid or Mix methods, Comparing Problem Based Learning with other strategies, and new trends and tendencies in Problem Based Learning related research. Our research may help us to identify the latest trends and tendencies referred to in the published studies related to “problem based learning” areas. In this research, Science Direct and Ulakbim were used as our main database resources. The sample of this study consists of 150 articles.

  5. A recursive Monte Carlo method for estimating importance functions in deep penetration problems

    International Nuclear Information System (INIS)

    Goldstein, M.

    1980-04-01

    A pratical recursive Monte Carlo method for estimating the importance function distribution, aimed at importance sampling for the solution of deep penetration problems in three-dimensional systems, was developed. The efficiency of the recursive method was investigated for sample problems including one- and two-dimensional, monoenergetic and and multigroup problems, as well as for a practical deep-penetration problem with streaming. The results of the recursive Monte Carlo calculations agree fairly well with Ssub(n) results. It is concluded that the recursive Monte Carlo method promises to become a universal method for estimating the importance function distribution for the solution of deep-penetration problems, in all kinds of systems: for many systems the recursive method is likely to be more efficient than previously existing methods; for three-dimensional systems it is the first method that can estimate the importance function with the accuracy required for an efficient solution based on importance sampling of neutron deep-penetration problems in those systems

  6. Infill sampling criteria to locate extremes

    CSIR Research Space (South Africa)

    Watson, AG

    1995-07-01

    Full Text Available Three problem-dependent meanings for engineering ''extremes'' are motivated, established, and translated into formal geostatistical (model-based) criteria for designing infill sample networks. (I) Locate an area within the domain of interest where a...

  7. Parent-reported problem behavior among children with sensory disabilities attending elementary regular schools

    NARCIS (Netherlands)

    Maes, B; Grietens, H

    2004-01-01

    Parent-reported problem behaviors of 94 children with visual and auditory disabilities, attending elementary regular schools, were compared with problems reported in a general population sample of nondisabled children. Both samples were matched by means of a pairwise matching procedure, taking into

  8. Competitiveness facets and sensation seeking as predictors of problem gambling among a sample of university student gamblers.

    Science.gov (United States)

    Harris, Nicholas; Newby, Jennifer; Klein, Rupert G

    2015-06-01

    Understanding the factors that contribute to problem gambling (PG) is imperative. Individual differences in sensation seeking (SS), as measured by the Sensation Seeking Scale Form (SSS-V), have been found to be predictive of PG among university student samples. However, what is less clear, is if the four SSS-V subscales capture unique facets of SS that are particularly predictive of PG. Much less studied than SS, competitiveness has also been found to be predictive of PG. The Competitiveness Orientation Measure (COM) is a newly developed measure of competitiveness, comprising of four facets. The main purpose of the current study was to examine if these four facets of competitiveness predicted variance in PG over and above the variance predicted by the four SSS-V subscales. Participants included 158 university student gamblers. Sequential regression analysis showed that after accounting for gender, age, and the four SSS-V subscales the only facet of the COM found to be a significant predictor of PG severity was Dominant Competitiveness. Dominant Competitiveness predicted an additional 11% of PG severity. These results provide support for the Dominant Competitiveness subscale of the COM as having utility in predicting PG over and above the predictive utility of the SSS-V subscales. Practical implications for the current findings are discussed.

  9. Estimating rare events in biochemical systems using conditional sampling

    Science.gov (United States)

    Sundar, V. S.

    2017-01-01

    The paper focuses on development of variance reduction strategies to estimate rare events in biochemical systems. Obtaining this probability using brute force Monte Carlo simulations in conjunction with the stochastic simulation algorithm (Gillespie's method) is computationally prohibitive. To circumvent this, important sampling tools such as the weighted stochastic simulation algorithm and the doubly weighted stochastic simulation algorithm have been proposed. However, these strategies require an additional step of determining the important region to sample from, which is not straightforward for most of the problems. In this paper, we apply the subset simulation method, developed as a variance reduction tool in the context of structural engineering, to the problem of rare event estimation in biochemical systems. The main idea is that the rare event probability is expressed as a product of more frequent conditional probabilities. These conditional probabilities are estimated with high accuracy using Monte Carlo simulations, specifically the Markov chain Monte Carlo method with the modified Metropolis-Hastings algorithm. Generating sample realizations of the state vector using the stochastic simulation algorithm is viewed as mapping the discrete-state continuous-time random process to the standard normal random variable vector. This viewpoint opens up the possibility of applying more sophisticated and efficient sampling schemes developed elsewhere to problems in stochastic chemical kinetics. The results obtained using the subset simulation method are compared with existing variance reduction strategies for a few benchmark problems, and a satisfactory improvement in computational time is demonstrated.

  10. Anxiety Sensitivity and Sleep-Related Problems in Anxious Youth

    Science.gov (United States)

    Weiner, Courtney L.; Elkins, Meredith; Pincus, Donna; Comer, Jonathan

    2015-01-01

    Anxiety disorders constitute the most common mental health disturbance experienced by youth. Sleep-related problems (SRPs) are highly prevalent among anxious youth and encompass a variety of problems including nighttime fears, insomnia, and refusal to sleep alone. Given that chronic sleep disturbance is associated with a range of behavioral and physical problems in youth and predicts future psychopathology, it is important to elucidate the nature of SRPs in anxious youth. The present study investigated the relationship between sleep problems and anxiety sensitivity in a sample of 101 anxious youth, ages 6–17. Heightened anxiety sensitivity significantly predicted prolonged sleep onset latency across the sample, even after accounting for severity of anxiety, depression, and age. Results support previous research indicating that SRPs are common among anxious youth and suggest that anxiety sensitivity may play a particularly important role in sleep onset latency. PMID:25863826

  11. Target Tracking of a Linear Time Invariant System under Irregular Sampling

    Directory of Open Access Journals (Sweden)

    Jin Xue-Bo

    2012-11-01

    Full Text Available Due to event-triggered sampling in a system, or maybe with the aim of reducing data storage, tracking many applications will encounter irregular sampling time. By calculating the matrix exponential using an inverse Laplace transform, this paper transforms the irregular sampling tracking problem to the problem of tracking with time-varying parameters of a system. Using the common Kalman filter, the developed method is used to track a target for the simulated trajectory and video tracking. The results of simulation experiments have shown that it can obtain good estimation performance even at a very high irregular rate of measurement sampling time.

  12. The contribution of parent and youth information to identify mental health disorders or problems in adolescents

    DEFF Research Database (Denmark)

    Aebi, Marcel; Kuhn, Christine; Banaschewski, Tobias

    2017-01-01

    were used to predict any problems/disorders, emotional problems/disorders and behavioural problems/disorders in a community sample (n = 252) and in a clinic sample (n = 95). RESULTS: The findings were strikingly similar in both samples. Parent and youth SDQ scales were related to any problem/disorder......BACKGROUND: Discrepancies between multiple informants often create considerable uncertainties in delivering services to youth. The present study assessed the ability of the parent and youth scales of the Strength and Difficulties Questionnaire (SDQ) to predict mental health problems/disorders....... Youth SDQ symptom and impact had the strongest association with emotional problems/disorder and parent SDQ symptom score were most strongly related to behavioural problems/disorders. Both the SDQ total and the impact scores significantly predicted emotional problems/disorders in males whereas...

  13. The Prevalence of Problem Gambling in Denmark in 2005 and 2010

    DEFF Research Database (Denmark)

    Ekholm, Ola; Eiberg, Stig; Davidsen, Michael

    2014-01-01

    Gambling is a worldwide phenomenon. For most persons this causes only small or no problems, but for some, pathological gambling can be the result of entering the gambling environment. The objectives were to estimate the past year and lifetime prevalence of problem gambling in the adult Danish...... population (16 years or older) in 2010 and trends since 2005 and, furthermore, to investigate whether problem gamblers differed from non-problem gamblers with regard to sociodemographic and socioeconomic factors. Data were derived from two national representative Danish health surveys. The survey in 2005...... was based on region-stratified random sample of 10,916 Danish citizens (response rate: 52.1 %) and the survey in 2010 was based on a random sample of 23,405 Danish citizens (response rate: 62.7 %). Problem gambling was defined using the lie/bet questionnaire. The past year prevalence of problem gamblers...

  14. Semi-blind identification of wideband MIMO channels via stochastic sampling

    OpenAIRE

    Andrieu, Christophe; Piechocki, Robert J.; McGeehan, Joe P.; Armour, Simon M.

    2003-01-01

    In this paper we address the problem of wide-band multiple-input multiple-output (MIMO) channel (multidimensional time invariant FIR filter) identification using Markov chains Monte Carlo methods. Towards this end we develop a novel stochastic sampling technique that produces a sequence of multidimensional channel samples. The method is semi-blind in the sense that it uses a very short training sequence. In such a framework the problem is no longer analytically tractable; hence we resort to s...

  15. Sample preparation techniques in trace element analysis by X-ray emission spectroscopy

    International Nuclear Information System (INIS)

    Valkovic, V.

    1983-11-01

    The report, written under a research contract with the IAEA, contains a detailed presentation of the most difficult problem encountered in the trace element analysis by methods of the X-ray emission spectroscopy, namely the sample preparation techniques. The following items are covered. Sampling - with specific consideration of aerosols, water, soil, biological materials, petroleum and its products, storage of samples and their handling. Pretreatment of samples - preconcentration, ashing, solvent extraction, ion exchange and electrodeposition. Sample preparations for PIXE - analysis - backings, target uniformity and homogeneity, effects of irradiation, internal standards and specific examples of preparation (aqueous, biological, blood serum and solid samples). Sample preparations for radioactive sources or tube excitation - with specific examples (water, liquid and solid samples, soil, geological, plants and tissue samples). Finally, the problem of standards and reference materials, as well as that of interlaboratory comparisons, is discussed

  16. Efficiently sampling conformations and pathways using the concurrent adaptive sampling (CAS) algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Surl-Hee; Grate, Jay W.; Darve, Eric F.

    2017-08-21

    Molecular dynamics (MD) simulations are useful in obtaining thermodynamic and kinetic properties of bio-molecules but are limited by the timescale barrier, i.e., we may be unable to efficiently obtain properties because we need to run microseconds or longer simulations using femtoseconds time steps. While there are several existing methods to overcome this timescale barrier and efficiently sample thermodynamic and/or kinetic properties, problems remain in regard to being able to sample un- known systems, deal with high-dimensional space of collective variables, and focus the computational effort on slow timescales. Hence, a new sampling method, called the “Concurrent Adaptive Sampling (CAS) algorithm,” has been developed to tackle these three issues and efficiently obtain conformations and pathways. The method is not constrained to use only one or two collective variables, unlike most reaction coordinate-dependent methods. Instead, it can use a large number of collective vari- ables and uses macrostates (a partition of the collective variable space) to enhance the sampling. The exploration is done by running a large number of short simula- tions, and a clustering technique is used to accelerate the sampling. In this paper, we introduce the new methodology and show results from two-dimensional models and bio-molecules, such as penta-alanine and triazine polymer

  17. Problem Solving Frameworks for Mathematics and Software Development

    Science.gov (United States)

    McMaster, Kirby; Sambasivam, Samuel; Blake, Ashley

    2012-01-01

    In this research, we examine how problem solving frameworks differ between Mathematics and Software Development. Our methodology is based on the assumption that the words used frequently in a book indicate the mental framework of the author. We compared word frequencies in a sample of 139 books that discuss problem solving. The books were grouped…

  18. MEMECAHKAN MASALAH GEOGRAFI MELALUI PROBLEM BASED LEARNING

    Directory of Open Access Journals (Sweden)

    Sujiono Sujiono

    2018-01-01

    Full Text Available This study aims to determine the effect of Problem Based Learning model on geography problem-solving sklills. This research model is quasi experiment with non-equivalent control group design. The subjects of the study were the students of XI IPS SMA Negeri 1 Pulau Laut Timur, academic year 2016/2017. The assessment instrument is an essay test based on an indicator of problem solving skills, ie (1 identifying problems; (2 formulate the problem; (3 finding alternative solutions; (4 choose alternative solutions; and (5 make conclusions. Data analysis using independent sample t-test model with 5% significance level. The results showed that there is an influence of PBL model on geography problem-solving sklills. The geography problem-solving skills of experimental class with PBL model is higher than control class with conventional model. Suggestion given, that is to make a plan of learning well and doing learning PBL on outdoor study.   Keywords Problem Based Learning, problem-solving skills, geography   http://dx.doi.org/10.17977/um022v2i22017p072

  19. Use of robotic systems for radiochemical sample changing and for analytical sample preparation

    International Nuclear Information System (INIS)

    Delmastro, J.R.; Hartenstein, S.D.; Wade, M.A.

    1989-01-01

    Two uses of the Perkin-Elmer (PE) robotic system will be presented. In the first, a PE robot functions as an automatic sample changer for up to five low energy photon spectrometry (LEPS) detectors operated with a Nuclear Data ND 6700 system. The entire system, including the robot, is controlled by an IBM PC-AT using software written in compiled BASIC. Problems associated with the development of the system and modifications to the robot will be presented. In the second, an evaluation study was performed to assess the abilities of the PE robotic system for performing complex analytical sample preparation procedures. For this study, a robotic system based upon the PE robot and auxiliary devices was constructed and programmed to perform the preparation of final product samples (UO 3 ) for accountability and impurity specification analyses. These procedures require sample dissolution, dilution, and liquid-liquid extraction steps. The results of an in-depth evaluation of all system components will be presented

  20. Neighborhood Environment and Internalizing Problems in African American Children

    OpenAIRE

    Milam, Adam J; Furr-Holden, C. Debra; Whitaker, Damiya; Smart, Mieka; Leaf, Philip; Cooley-Strickland, Michele

    2011-01-01

    This study examines gender differences in the association between environment and internalizing problems in a sample of predominately African American schoolchildren. Internalizing problems was assessed using the Youth Self Report. Violence and alcohol and other drug (AOD) exposure subscales were created using observational assessments of neighborhood blocks. Logistic regression models were used to assess the relationship between neighborhood environment and internalizing problems. For each A...

  1. Computational methods and modeling. 1. Sampling a Position Uniformly in a Trilinear Hexahedral Volume

    International Nuclear Information System (INIS)

    Urbatsch, Todd J.; Evans, Thomas M.; Hughes, H. Grady

    2001-01-01

    Monte Carlo particle transport plays an important role in some multi-physics simulations. These simulations, which may additionally involve deterministic calculations, typically use a hexahedral or tetrahedral mesh. Trilinear hexahedrons are attractive for physics calculations because faces between cells are uniquely defined, distance-to-boundary calculations are deterministic, and hexahedral meshes tend to require fewer cells than tetrahedral meshes. We discuss one aspect of Monte Carlo transport: sampling a position in a tri-linear hexahedron, which is made up of eight control points, or nodes, and six bilinear faces, where each face is defined by four non-coplanar nodes in three-dimensional Cartesian space. We derive, code, and verify the exact sampling method and propose an approximation to it. Our proposed approximate method uses about one-third the memory and can be twice as fast as the exact sampling method, but we find that its inaccuracy limits its use to well-behaved hexahedrons. Daunted by the expense of the exact method, we propose an alternate approximate sampling method. First, calculate beforehand an approximate volume for each corner of the hexahedron by taking one-eighth of the volume of an imaginary parallelepiped defined by the corner node and the three nodes to which it is directly connected. For the sampling, assume separability in the parameters, and sample each parameter, in turn, from a linear pdf defined by the sum of the four corner volumes at each limit (-1 and 1) of the parameter. This method ignores the quadratic portion of the pdf, but it requires less storage, has simpler sampling, and needs no extra, on-the-fly calculations. We simplify verification by designing tests that consist of one or more cells that entirely fill a unit cube. Uniformly sampling complicated cells that fill a unit cube will result in uniformly sampling the unit cube. Unit cubes are easily analyzed. The first problem has four wedges (or tents, or A frames) whose

  2. Sampling free energy surfaces as slices by combining umbrella sampling and metadynamics.

    Science.gov (United States)

    Awasthi, Shalini; Kapil, Venkat; Nair, Nisanth N

    2016-06-15

    Metadynamics (MTD) is a very powerful technique to sample high-dimensional free energy landscapes, and due to its self-guiding property, the method has been successful in studying complex reactions and conformational changes. MTD sampling is based on filling the free energy basins by biasing potentials and thus for cases with flat, broad, and unbound free energy wells, the computational time to sample them becomes very large. To alleviate this problem, we combine the standard Umbrella Sampling (US) technique with MTD to sample orthogonal collective variables (CVs) in a simultaneous way. Within this scheme, we construct the equilibrium distribution of CVs from biased distributions obtained from independent MTD simulations with umbrella potentials. Reweighting is carried out by a procedure that combines US reweighting and Tiwary-Parrinello MTD reweighting within the Weighted Histogram Analysis Method (WHAM). The approach is ideal for a controlled sampling of a CV in a MTD simulation, making it computationally efficient in sampling flat, broad, and unbound free energy surfaces. This technique also allows for a distributed sampling of a high-dimensional free energy surface, further increasing the computational efficiency in sampling. We demonstrate the application of this technique in sampling high-dimensional surface for various chemical reactions using ab initio and QM/MM hybrid molecular dynamics simulations. Further, to carry out MTD bias reweighting for computing forward reaction barriers in ab initio or QM/MM simulations, we propose a computationally affordable approach that does not require recrossing trajectories. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  3. Problem Posing with Realistic Mathematics Education Approach in Geometry Learning

    Science.gov (United States)

    Mahendra, R.; Slamet, I.; Budiyono

    2017-09-01

    One of the difficulties of students in the learning of geometry is on the subject of plane that requires students to understand the abstract matter. The aim of this research is to determine the effect of Problem Posing learning model with Realistic Mathematics Education Approach in geometry learning. This quasi experimental research was conducted in one of the junior high schools in Karanganyar, Indonesia. The sample was taken using stratified cluster random sampling technique. The results of this research indicate that the model of Problem Posing learning with Realistic Mathematics Education Approach can improve students’ conceptual understanding significantly in geometry learning especially on plane topics. It is because students on the application of Problem Posing with Realistic Mathematics Education Approach are become to be active in constructing their knowledge, proposing, and problem solving in realistic, so it easier for students to understand concepts and solve the problems. Therefore, the model of Problem Posing learning with Realistic Mathematics Education Approach is appropriately applied in mathematics learning especially on geometry material. Furthermore, the impact can improve student achievement.

  4. An adaptive sampling scheme for deep-penetration calculation

    International Nuclear Information System (INIS)

    Wang, Ruihong; Ji, Zhicheng; Pei, Lucheng

    2013-01-01

    As we know, the deep-penetration problem has been one of the important and difficult problems in shielding calculation with Monte Carlo Method for several decades. In this paper, an adaptive Monte Carlo method under the emission point as a sampling station for shielding calculation is investigated. The numerical results show that the adaptive method may improve the efficiency of the calculation of shielding and might overcome the under-estimation problem easy to happen in deep-penetration calculation in some degree

  5. Treatment of Nuclear Data Covariance Information in Sample Generation

    Energy Technology Data Exchange (ETDEWEB)

    Swiler, Laura Painton [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Adams, Brian M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wieselquist, William [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Reactor and Nuclear Systems Division

    2017-10-01

    This report summarizes a NEAMS (Nuclear Energy Advanced Modeling and Simulation) project focused on developing a sampling capability that can handle the challenges of generating samples from nuclear cross-section data. The covariance information between energy groups tends to be very ill-conditioned and thus poses a problem using traditional methods for generated correlated samples. This report outlines a method that addresses the sample generation from cross-section matrices.

  6. Treatment of Nuclear Data Covariance Information in Sample Generation

    International Nuclear Information System (INIS)

    Swiler, Laura Painton; Adams, Brian M.; Wieselquist, William

    2017-01-01

    This report summarizes a NEAMS (Nuclear Energy Advanced Modeling and Simulation) project focused on developing a sampling capability that can handle the challenges of generating samples from nuclear cross-section data. The covariance information between energy groups tends to be very ill-conditioned and thus poses a problem using traditional methods for generated correlated samples. This report outlines a method that addresses the sample generation from cross-section matrices.

  7. Big Data, Small Sample.

    Science.gov (United States)

    Gerlovina, Inna; van der Laan, Mark J; Hubbard, Alan

    2017-05-20

    Multiple comparisons and small sample size, common characteristics of many types of "Big Data" including those that are produced by genomic studies, present specific challenges that affect reliability of inference. Use of multiple testing procedures necessitates calculation of very small tail probabilities of a test statistic distribution. Results based on large deviation theory provide a formal condition that is necessary to guarantee error rate control given practical sample sizes, linking the number of tests and the sample size; this condition, however, is rarely satisfied. Using methods that are based on Edgeworth expansions (relying especially on the work of Peter Hall), we explore the impact of departures of sampling distributions from typical assumptions on actual error rates. Our investigation illustrates how far the actual error rates can be from the declared nominal levels, suggesting potentially wide-spread problems with error rate control, specifically excessive false positives. This is an important factor that contributes to "reproducibility crisis". We also review some other commonly used methods (such as permutation and methods based on finite sampling inequalities) in their application to multiple testing/small sample data. We point out that Edgeworth expansions, providing higher order approximations to the sampling distribution, offer a promising direction for data analysis that could improve reliability of studies relying on large numbers of comparisons with modest sample sizes.

  8. A simple homogeneous model for regular and irregular metallic wire media samples

    Science.gov (United States)

    Kosulnikov, S. Y.; Mirmoosa, M. S.; Simovski, C. R.

    2018-02-01

    To simplify the solution of electromagnetic problems with wire media samples, it is reasonable to treat them as the samples of a homogeneous material without spatial dispersion. The account of spatial dispersion implies additional boundary conditions and makes the solution of boundary problems difficult especially if the sample is not an infinitely extended layer. Moreover, for a novel type of wire media - arrays of randomly tilted wires - a spatially dispersive model has not been developed. Here, we introduce a simplistic heuristic model of wire media samples shaped as bricks. Our model covers WM of both regularly and irregularly stretched wires.

  9. Music Taste Groups and Problem Behavior.

    Science.gov (United States)

    Mulder, Juul; Bogt, Tom Ter; Raaijmakers, Quinten; Vollebergh, Wilma

    2007-04-01

    Internalizing and externalizing problems differ by musical tastes. A high school-based sample of 4159 adolescents, representative of Dutch youth aged 12 to 16, reported on their personal and social characteristics, music preferences and social-psychological functioning, measured with the Youth Self-Report (YSR). Cluster analysis on their music preferences revealed six taste groups: Middle-of-the-road (MOR) listeners, Urban fans, Exclusive Rock fans, Rock-Pop fans, Elitists, and Omnivores. A seventh group of musically Low-Involved youth was added. Multivariate analyses revealed that when gender, age, parenting, school, and peer variables were controlled, Omnivores and fans within the Exclusive Rock groups showed relatively high scores on internalizing YSR measures, and social, thought and attention problems. Omnivores, Exclusive Rock, Rock-Pop and Urban fans reported more externalizing problem behavior. Belonging to the MOR group that highly appreciates the most popular, chart-based pop music appears to buffer problem behavior. Music taste group membership uniquely explains variance in both internalizing and externalizing problem behavior.

  10. The problem of large samples. An activation analysis study of electronic waste material

    International Nuclear Information System (INIS)

    Segebade, C.; Goerner, W.; Bode, P.

    2007-01-01

    Large-volume instrumental photon activation analysis (IPAA) was used for the investigation of shredded electronic waste material. Sample masses from 1 to 150 grams were analyzed to obtain an estimate of the minimum sample size to be taken to achieve a representativeness of the results which is satisfactory for a defined investigation task. Furthermore, the influence of irradiation and measurement parameters upon the quality of the analytical results were studied. Finally, the analytical data obtained from IPAA and instrumental neutron activation analysis (INAA), both carried out in a large-volume mode, were compared. Only parts of the values were found in satisfactory agreement. (author)

  11. DWPF liquid sample station: Status of equipment development

    International Nuclear Information System (INIS)

    Caplan, J.R.

    1987-01-01

    This report summarizes operating experience and equipment status of the DWPF liquid sample cell. Operation hours to date, results of equipment inspections and problems encountered and their solutions are discussed. An equipment and instrumentation status updating DPST-85-592, DWPF LIQUID SAMPLE CELL MOCK-UP, is presented. Remaining development items are also outlined

  12. Sampled-Data Control of Spacecraft Rendezvous with Discontinuous Lyapunov Approach

    Directory of Open Access Journals (Sweden)

    Zhuoshi Li

    2013-01-01

    Full Text Available This paper investigates the sampled-data stabilization problem of spacecraft relative positional holding with improved Lyapunov function approach. The classical Clohessy-Wiltshire equation is adopted to describe the relative dynamic model. The relative position holding problem is converted into an output tracking control problem using sampling signals. A time-dependent discontinuous Lyapunov functionals approach is developed, which will lead to essentially less conservative results for the stability analysis and controller design of the corresponding closed-loop system. Sufficient conditions for the exponential stability analysis and the existence of the proposed controller are provided, respectively. Finally, a simulation result is established to illustrate the effectiveness of the proposed control scheme.

  13. Quantum Metropolis sampling.

    Science.gov (United States)

    Temme, K; Osborne, T J; Vollbrecht, K G; Poulin, D; Verstraete, F

    2011-03-03

    The original motivation to build a quantum computer came from Feynman, who imagined a machine capable of simulating generic quantum mechanical systems--a task that is believed to be intractable for classical computers. Such a machine could have far-reaching applications in the simulation of many-body quantum physics in condensed-matter, chemical and high-energy systems. Part of Feynman's challenge was met by Lloyd, who showed how to approximately decompose the time evolution operator of interacting quantum particles into a short sequence of elementary gates, suitable for operation on a quantum computer. However, this left open the problem of how to simulate the equilibrium and static properties of quantum systems. This requires the preparation of ground and Gibbs states on a quantum computer. For classical systems, this problem is solved by the ubiquitous Metropolis algorithm, a method that has basically acquired a monopoly on the simulation of interacting particles. Here we demonstrate how to implement a quantum version of the Metropolis algorithm. This algorithm permits sampling directly from the eigenstates of the Hamiltonian, and thus evades the sign problem present in classical simulations. A small-scale implementation of this algorithm should be achievable with today's technology.

  14. Guidelines for sampling fish in inland waters

    National Research Council Canada - National Science Library

    Backiel, Tadeusz; Welcomme, R. L

    1980-01-01

    The book is addressed mainly to Fishery Biologists but it is hoped that Fishing Gear Technologists also can acquire some basic knowledge of sampling problems and procedures which, in turn, can result...

  15. Patch-based visual tracking with online representative sample selection

    Science.gov (United States)

    Ou, Weihua; Yuan, Di; Li, Donghao; Liu, Bin; Xia, Daoxun; Zeng, Wu

    2017-05-01

    Occlusion is one of the most challenging problems in visual object tracking. Recently, a lot of discriminative methods have been proposed to deal with this problem. For the discriminative methods, it is difficult to select the representative samples for the target template updating. In general, the holistic bounding boxes that contain tracked results are selected as the positive samples. However, when the objects are occluded, this simple strategy easily introduces the noises into the training data set and the target template and then leads the tracker to drift away from the target seriously. To address this problem, we propose a robust patch-based visual tracker with online representative sample selection. Different from previous works, we divide the object and the candidates into several patches uniformly and propose a score function to calculate the score of each patch independently. Then, the average score is adopted to determine the optimal candidate. Finally, we utilize the non-negative least square method to find the representative samples, which are used to update the target template. The experimental results on the object tracking benchmark 2013 and on the 13 challenging sequences show that the proposed method is robust to the occlusion and achieves promising results.

  16. The Effect of Reading Comprehension and Problem Solving Strategies on Classifying Elementary 4th Grade Students with High and Low Problem Solving Success

    Science.gov (United States)

    Ulu, Mustafa

    2017-01-01

    In this study, the effect of fluent reading (speed, reading accuracy percentage, prosodic reading), comprehension (literal comprehension, inferential comprehension) and problem solving strategies on classifying students with high and low problem solving success was researched. The sampling of the research is composed of 279 students at elementary…

  17. Turkish and Moroccan Young Adults in the Netherlands: The Relationship Between Acculturation and Psychological Problems.

    Science.gov (United States)

    Özbek, Emel; Bongers, Ilja L; Lobbestael, Jill; van Nieuwenhuizen, Chijs

    2015-12-01

    This study investigated the relationship between acculturation and psychological problems in Turkish and Moroccan young adults living in the Netherlands. A sample of 131 healthy young adults aged between 18 and 24 years old, with a Turkish or Moroccan background was recruited using snowball sampling. Data on acculturation, internalizing and externalizing problems, beliefs about psychological problems, attributions of psychological problems and barriers to care were collected and analyzed using Latent Class Analysis and multinomial logistic regression. Three acculturation classes were identified in moderately to highly educated, healthy Turkish or Moroccan young adults: integration, separation and diffusion. None of the participants in the sample were marginalized or assimilated. Young adults reporting diffuse acculturation reported more internalizing and externalizing problems than those who were integrated or separated. Separated young adults reported experiencing more practical barriers to care than integrated young adults. Further research with a larger sample, including young adult migrants using mental health services, is required to improve our understanding of acculturation, psychological problems and barriers to care in this population. Including experiences of discrimination in the model might improve our understanding of the relationship between different forms of acculturation and psychological problems.

  18. Sociodemographic and health correlates of sleep problems and ...

    African Journals Online (AJOL)

    Objective. To investigate sleeping problems, sleep duration and associated factors in a national probability sample of older South Africans who participated in the Study of Global Ageing and Adult Health (SAGE) in 2008. Methods. In 2008 I conducted a national population-based cross-sectional study with a sample of 3 840 ...

  19. Agricultural problems

    International Nuclear Information System (INIS)

    Bickerton, George E.

    1997-01-01

    Although there were not reasons to deplore against major activity release from any of the 110 industrial reactors authorized to operate in US, the nuclear incident that occurred at the Three Mile Island Plant in 1979 urged the public conscience toward the necessity of readiness to cope with events of this type. The personnel of the Emergency Planning Office functioning in the frame of US Department of Agriculture has already participated in around 600 intervention drillings on a federal, local or state scale to plan, test or asses radiological emergency plans or to intervene locally. These exercises allowed acquiring a significant experience in elaborating emergency plans, planning the drillings, working out scenarios and evaluation of the potential impact of accidents from the agricultural point of view. We have also taken part in different international drillings among which the most recent are INEX 1 and RADEX 94. We have found on these occasions that the agricultural problems are essential preoccupations in most of the cases no matter if the context is international, national, local or of state level. The paper poses problems specifically related to milk, fruits and vegetables, soils, meat and meat products. Finally the paper discusses issues like drilling planning, alarm and notification, sampling strategy, access authorizations for farmers, removing of contamination wastes. A number of social, political and economical relating problems are also mentioned

  20. The use of Thompson sampling to increase estimation precision

    NARCIS (Netherlands)

    Kaptein, M.C.

    2015-01-01

    In this article, we consider a sequential sampling scheme for efficient estimation of the difference between the means of two independent treatments when the population variances are unequal across groups. The sampling scheme proposed is based on a solution to bandit problems called Thompson

  1. The relation of eating problems and amenorrhea in ballet dancers.

    Science.gov (United States)

    Brooks-Gunn, J; Warren, M P; Hamilton, L H

    1987-02-01

    Exercise-induced amenorrhea has received considerable attention in the medical literature. The combination of exercise and low body weight is thought to exert synergistic effects in the pathogenesis of amenorrhea, while the role of dieting and eating problems, another possible causative mechanism, has not been examined. A sample of 55 adult dancers in national and regional classical ballet companies was studied; their mean age was 24.7 yr. Fifty-six percent of the dancers had delayed menarche (age 14 or later) and 19% of the sample were currently amenorrheic (5 months or longer). One-third of the dancers reported having had an eating problem (self-reported anorexia nervosa or bulimia). Amenorrhea and reported eating problems were significantly related: 50% of amenorrheics reported anorexia nervosa while 13% of the normals did. In addition, prolonged amenorrhea was significantly related to dieting (as measured by EAT-26 scales, a measure of dieting behavior). As expected, leanness and absolute weight also were related to prolonged amenorrhea. Amenorrhea in this sample of adult dancers was not related to current activity level or age at which training began. Thus, eating problems may be one factor in the pathogenesis of prolonged amenorrhea in certain athletic groups.

  2. Sampling problems and the determination of mercury in surface water, seawater, and air

    International Nuclear Information System (INIS)

    Das, H.A.; van der Sloot, H.A.

    1976-01-01

    Analysis of surface water for mercury comprises the determination of both ionic and organically bound mercury in solution and that of the total mercury content of the suspended matter. Eventually, metallic mercury has to be determined too. Requirements for the sampling procedure are given. A method for the routine determination of mercury in surface water and seawater was developed and applied to Dutch surface waters. The total sample volume is 2500 ml. About 500 ml is used for the determination of the content of suspended matter and the total amount of mercury in the water. The sample is filtered through a bed of previously purified active charcoal at a low flow-rate. The main portion ca. 2000 ml) passes a flow-through centrifuge to separate the solid fraction. One liter is used to separate ''inorganic'' mercury by reduction, volatilization in an airstream and adsorption on active charcoal. The other liter is led through a column of active charcoal to collect all mercury. The procedures were checked with 197 Hg radiotracer both as an ion and incorporated in organic compounds. The mercury is determined by thermal neutron activation, followed by volatilization in a tube furnace and adsorption on a fresh carbon bed. The limit of determination is approximately equal to 1 ng 1 -1 . The rate of desorption from and adsorption on suspended material has been measured as a function of a pH of the solution for Hg +2 and various other ions. It can be concluded that only the procedure mentioned above does not disturb the equilibrium. The separation of mercury from air is obtained by suction of 1 m 3 through a 0.22 μm filter and a charcoal bed. The determination is then performed as in the case of the water samples

  3. Interpersonal problems across anxiety, depression, and eating disorders: a transdiagnostic examination.

    Science.gov (United States)

    McEvoy, Peter M; Burgess, Melissa M; Page, Andrew C; Nathan, Paula; Fursland, Anthea

    2013-06-01

    Integrative models of psychopathology suggest that quality of interpersonal relationships is a key determinant of psychological well-being. However, there is a relative paucity of research evaluating the association between interpersonal problems and psychopathology within cognitive behavioural therapy. Partly, this may be due to lack of brief, well-validated, and easily interpretable measures of interpersonal problems that can be used within clinical settings. The aim of the present study was to evaluate the psychometric properties, factor invariance, and external validity of the Inventory of Interpersonal Problems 32 (IIP-32) across anxiety, depression, and eating disorders. Two treatment-seeking samples with principal anxiety and depressive disorders (AD sample, n = 504) and eating disorders (ED sample, n = 339) completed the IIP-32 along with measures of anxiety, depression, and eating disorder symptoms, as well as quality of life (QoL). The previously established eight-factor structure of the IIP-32 provided the best fit for both the AD and ED groups, and was robustly invariant across the two samples. The IIP-32 also demonstrated excellent external validity against well-validated measures of anxiety, depression, and eating disorder symptoms, as well as QoL. The IIP-32 provides a clinically useful measure of interpersonal problems across emotional and ED. © Commonwealth of Australia 2012.

  4. Familial confounding of the association between maternal smoking during pregnancy and offspring substance use and problems.

    Science.gov (United States)

    D'Onofrio, Brian M; Rickert, Martin E; Langström, Niklas; Donahue, Kelly L; Coyne, Claire A; Larsson, Henrik; Ellingson, Jarrod M; Van Hulle, Carol A; Iliadou, Anastasia N; Rathouz, Paul J; Lahey, Benjamin B; Lichtenstein, Paul

    2012-11-01

    Previous epidemiological, animal, and human cognitive neuroscience research suggests that maternal smoking during pregnancy (SDP) causes increased risk of substance use/problems in offspring. To determine the extent to which the association between SDP and offspring substance use/problems depends on confounded familial background factors by using a quasi-experimental design. We used 2 separate samples from the United States and Sweden. The analyses prospectively predicted multiple indices of substance use and problems while controlling for statistical covariates and comparing differentially exposed siblings to minimize confounding. Offspring of a representative sample of women in the United States (sample 1) and the total Swedish population born during the period from January 1, 1983, to December 31, 1995 (sample 2). Adolescent offspring of the women in the National Longitudinal Survey of Youth 1979 (n = 6904) and all offspring born in Sweden during the 13-year period (n = 1,187,360). Self-reported adolescent alcohol, cigarette, and marijuana use and early onset (before 14 years of age) of each substance (sample 1) and substance-related convictions and hospitalizations for an alcohol- or other drug-related problem (sample 2). The same pattern emerged for each index of substance use/problems across the 2 samples. At the population level, maternal SDP predicted every measure of offspring substance use/problems in both samples, ranging from adolescent alcohol use (hazard ratio [HR](moderate), 1.32 [95% CI, 1.22-1.43]; HR(high), 1.33 [1.17-1.53]) to a narcotics-related conviction (HR(moderate), 2.23 [2.14-2.31]; HR(high), 2.97 [2.86-3.09]). When comparing differentially exposed siblings to minimize genetic and environmental confounds, however, the association between SDP and each measure of substance use/problems was minimal and not statistically significant. The association between maternal SDP and offspring substance use/problems is likely due to familial background

  5. Structuring Word Problems for Diagnostic Teaching: Helping Teachers Meet the Needs of Children with Mild Disabilities.

    Science.gov (United States)

    Parmar, Rene S.; Cawley, John F.

    1994-01-01

    Matrix organization can be used to construct math word problems for children with mild disabilities. Matrix organization specifies the characteristics of problems, such as problem theme or setting, operations, level of computation complexity, reading vocabulary level, and need for classification. A sample scope and sequence and 16 sample word…

  6. Different stability of social-communication problems and negative demanding behaviour from infancy to toddlerhood in a large Dutch population sample

    Science.gov (United States)

    2014-01-01

    Background Little is known about the stability of behavioural and developmental problems as children develop from infants to toddlers in the general population. Therefore, we investigated behavioural profiles at two time points and determined whether behaviours are stable during early development. Methods Parents of 4,237 children completed questionnaires with 62 items about externalizing, internalizing, and social-communicative behaviour when the children were 14–15 and 36–37 months old. Factor mixture modelling identified five homogeneous profiles at both time points: three with relatively normal behaviour or with mild/moderate problems, one with clear communication and interaction problems, and another with pronounced negative and demanding behaviour. Results More than 85% of infants with normal behaviour or mild problems at 14–15 months were reported to behave relatively typically as toddlers at 36–37 months. A similar percentage of infants with moderate communication problems outgrew their problems by the time they were toddlers. However, infants with severe problems had mild to severe problems as toddlers, and did not show completely normal behaviour. Improvement over time occurred more often in children with negative and demanding behaviour than in children with communication and interaction problems. The former showed less homotypic continuity than the latter. Conclusions Negative and demanding behaviour is more often transient and a less specific predictor of problems in toddlerhood than communication and interaction problems. PMID:25061477

  7. Predictors of Parent Stress in a Sample of Children with ASD: Pain, Problem Behavior, and Parental Coping

    Science.gov (United States)

    Walsh, Caitlin E.; Mulder, Emile; Tudor, Megan E.

    2013-01-01

    Studies have shown that children with ASD have increased severity and incidence of pain symptoms compared to typically developing children and children with other disorders. Pain has also been shown to act as a setting event for problem behavior. Further, problem behavior is one of the biggest impediments to quality of life for families and highly…

  8. Sample Size Bounding and Context Ranking as Approaches to the Human Error Quantification Problem

    Energy Technology Data Exchange (ETDEWEB)

    Reer, B

    2004-03-01

    The paper describes a technique denoted as Sub-Sample-Size Bounding (SSSB), which is useable for the statistical derivation of context-specific probabilities from data available in existing reports on operating experience. Applications to human reliability analysis (HRA) are emphasised in the presentation of this technique. Exemplified by a sample of 180 abnormal event sequences, the manner in which SSSB can provide viable input for the quantification of errors of commission (EOCs) are outlined. (author)

  9. Sample Size Bounding and Context Ranking as Approaches to the Human Error Quantification Problem

    International Nuclear Information System (INIS)

    Reer, B.

    2004-01-01

    The paper describes a technique denoted as Sub-Sample-Size Bounding (SSSB), which is useable for the statistical derivation of context-specific probabilities from data available in existing reports on operating experience. Applications to human reliability analysis (HRA) are emphasised in the presentation of this technique. Exemplified by a sample of 180 abnormal event sequences, the manner in which SSSB can provide viable input for the quantification of errors of commission (EOCs) are outlined. (author)

  10. Radiocarbon dating of interlaboratory check samples

    International Nuclear Information System (INIS)

    Blake, W.

    1983-01-01

    This note presents the results of a series of interlaboratory age determinations in which the Geological Survey of Canada's Radiocarbon Dating Laboratory has been involved. There is good agreement between laboratories, although there may be other problems related to the interpretation of individual samples

  11. Perceived social environment and adolescents' well-being and adjustment: Comparing a foster care sample with a matched sample

    OpenAIRE

    Farruggia, SP; Greenberger, E; Chen, C; Heckhausen, J

    2006-01-01

    Previous research has demonstrated that former foster care youth are at risk for poor outcomes (e.g., more problem behaviors, more depression, lower self-esteem, and poor social relationships). It is not clear, however, whether these findings reflect preemancipation developmental deficits. This study used 163 preemancipation foster care youth and a matched sample of 163 comparison youth. Results showed that foster-care youth did not differ from the comparison sample on measures of well-being,...

  12. CT-scan-monitored electrical-resistivity measurements show problems achieving homogeneous saturation

    International Nuclear Information System (INIS)

    Sprunt, E.S.; Davis, R.M.; Muegge, E.L.; Desai, K.P.

    1991-01-01

    This paper reports on x-ray computerized tomography (CT) scans obtained during measurement of the electrical resistivity of core samples which revealed some problems in obtaining uniform saturation along the lengths of the samples. The electrical resistivity of core samples is measured as a function of water saturation to determine the saturation exponent used in electric-log interpretation. An assumption in such tests is that the water saturation is uniformly distributed. Failure of this assumption can result in errors in the determination of the saturation exponent. Three problems were identified in obtaining homogeneous water saturation in two samples of a Middle Eastern carbonate grainstone: a stationary front formed in one sample at 1-psi oil/brine capillary pressure, a moving front formed at oil/brine capillary pressure ≤4 psi in samples tested in fresh mixed-wettability and cleaned water-wet states, and the heterogeneous fluid distribution caused by a rapidly moving front did not dissipate when the capillary pressure was eliminated in the samples

  13. Correlates of interpersonal dependency and detachment in an adolescent inpatient sample.

    Science.gov (United States)

    Haggerty, Greg; Siefert, Caleb J; Bornstein, Robert F; Sinclair, Samuel Justin; Blais, Mark A; Zodan, Jennifer; Rao, Nyapati

    2015-01-01

    Interpersonal dependency has been linked to psychological distress, depression, help seeking, treatment compliance, and sensitivity to interpersonal cues in adult samples. However, there is a dearth of research focusing on dependency in child and adolescent samples. The current study examined the construct validity of a measure of interpersonal dependency. The authors investigated how interpersonal dependency and detachment relate to behavioral problems, subjective well-being, interpersonal problems, and global symptom severity in adolescent inpatients. Destructive overdependence (DO) and dysfunctional detachment (DD) were positively related to interpersonal distress, behavioral problems, and symptom severity and negatively related to psychological health and well-being. Healthy dependency (HD) was associated with fewer behavioral problems and less symptom severity and positively related to subjective well-being. The clinical implications of these findings are discussed.

  14. Comparison of optimal design methods in inverse problems

    International Nuclear Information System (INIS)

    Banks, H T; Holm, K; Kappel, F

    2011-01-01

    Typical optimal design methods for inverse or parameter estimation problems are designed to choose optimal sampling distributions through minimization of a specific cost function related to the resulting error in parameter estimates. It is hoped that the inverse problem will produce parameter estimates with increased accuracy using data collected according to the optimal sampling distribution. Here we formulate the classical optimal design problem in the context of general optimization problems over distributions of sampling times. We present a new Prohorov metric-based theoretical framework that permits one to treat succinctly and rigorously any optimal design criteria based on the Fisher information matrix. A fundamental approximation theory is also included in this framework. A new optimal design, SE-optimal design (standard error optimal design), is then introduced in the context of this framework. We compare this new design criterion with the more traditional D-optimal and E-optimal designs. The optimal sampling distributions from each design are used to compute and compare standard errors; the standard errors for parameters are computed using asymptotic theory or bootstrapping and the optimal mesh. We use three examples to illustrate ideas: the Verhulst–Pearl logistic population model (Banks H T and Tran H T 2009 Mathematical and Experimental Modeling of Physical and Biological Processes (Boca Raton, FL: Chapman and Hall/CRC)), the standard harmonic oscillator model (Banks H T and Tran H T 2009) and a popular glucose regulation model (Bergman R N, Ider Y Z, Bowden C R and Cobelli C 1979 Am. J. Physiol. 236 E667–77; De Gaetano A and Arino O 2000 J. Math. Biol. 40 136–68; Toffolo G, Bergman R N, Finegood D T, Bowden C R and Cobelli C 1980 Diabetes 29 979–90)

  15. Comparison of optimal design methods in inverse problems

    Science.gov (United States)

    Banks, H. T.; Holm, K.; Kappel, F.

    2011-07-01

    Typical optimal design methods for inverse or parameter estimation problems are designed to choose optimal sampling distributions through minimization of a specific cost function related to the resulting error in parameter estimates. It is hoped that the inverse problem will produce parameter estimates with increased accuracy using data collected according to the optimal sampling distribution. Here we formulate the classical optimal design problem in the context of general optimization problems over distributions of sampling times. We present a new Prohorov metric-based theoretical framework that permits one to treat succinctly and rigorously any optimal design criteria based on the Fisher information matrix. A fundamental approximation theory is also included in this framework. A new optimal design, SE-optimal design (standard error optimal design), is then introduced in the context of this framework. We compare this new design criterion with the more traditional D-optimal and E-optimal designs. The optimal sampling distributions from each design are used to compute and compare standard errors; the standard errors for parameters are computed using asymptotic theory or bootstrapping and the optimal mesh. We use three examples to illustrate ideas: the Verhulst-Pearl logistic population model (Banks H T and Tran H T 2009 Mathematical and Experimental Modeling of Physical and Biological Processes (Boca Raton, FL: Chapman and Hall/CRC)), the standard harmonic oscillator model (Banks H T and Tran H T 2009) and a popular glucose regulation model (Bergman R N, Ider Y Z, Bowden C R and Cobelli C 1979 Am. J. Physiol. 236 E667-77 De Gaetano A and Arino O 2000 J. Math. Biol. 40 136-68 Toffolo G, Bergman R N, Finegood D T, Bowden C R and Cobelli C 1980 Diabetes 29 979-90).

  16. Detection of Chlamydophila psittaci from feral pigeons in environmental samples: problems with currently available techniques.

    Science.gov (United States)

    Geigenfeind, Ila; Haag-Wackernagel, Daniel

    2010-03-01

    Chlamydophila psittaci (Lillie, 1930) Everett et al., 1999, the pathogenic agent of human ornithosis, is widespread in feral pigeon populations and many cases of transmission from feral pigeons to humans have been reported. The aim of the present study was to detect C. psittaci in environmental samples to find out more about possible transmission routes and, therefore, to assess the zoonotic risk for humans. Fecal samples were collected from nest boxes in a feral pigeon loft. Additionally, samples were taken from the feather dust film covering the water surface of public fountains where pigeons regularly bathe. The samples were tested for the presence of chlamydial antigen using an antigen enzyme-linked immunosorbent assay to prove shedding of C. psittaci by feral pigeons. This test detects a genus specific lipopolysaccharide in the outer membrane of the chlamydial bacteria. Samples were tested using the IDEIA PCE Chlamydia Test kit (DakoCytomation) and positive results were verified with IDEIA Chlamydia Blocking Reagents (DakoCytomation). The IDEIA PCE Chlamydia Test yields a high proportion of positive results. However, when IDEIA Chlamydia Blocking was performed, most of the positive results turned out to be negative or could not be interpreted. We conclude that antigen-enzyme-linked immunosorbent assay tests are not suitable for detecting C. psittaci in environmental samples. Previous publications where no blocking test was used should be reconsidered critically. © 2010 ISZS, Blackwell Publishing and IOZ/CAS.

  17. Hot sample archiving. Revision 3

    International Nuclear Information System (INIS)

    McVey, C.B.

    1995-01-01

    This Engineering Study revision evaluated the alternatives to provide tank waste characterization analytical samples for a time period as recommended by the Tank Waste Remediation Systems Program. The recommendation of storing 40 ml segment samples for a period of approximately 18 months (6 months past the approval date of the Tank Characterization Report) and then composite the core segment material in 125 ml containers for a period of five years. The study considers storage at 222-S facility. It was determined that the critical storage problem was in the hot cell area. The 40 ml sample container has enough material for approximately 3 times the required amount for a complete laboratory re-analysis. The final result is that 222-S can meet the sample archive storage requirements. During the 100% capture rate the capacity is exceeded in the hot cell area, but quick, inexpensive options are available to meet the requirements

  18. Recursive Monte Carlo method for deep-penetration problems

    International Nuclear Information System (INIS)

    Goldstein, M.; Greenspan, E.

    1980-01-01

    The Recursive Monte Carlo (RMC) method developed for estimating importance function distributions in deep-penetration problems is described. Unique features of the method, including the ability to infer the importance function distribution pertaining to many detectors from, essentially, a single M.C. run and the ability to use the history tape created for a representative region to calculate the importance function in identical regions, are illustrated. The RMC method is applied to the solution of two realistic deep-penetration problems - a concrete shield problem and a Tokamak major penetration problem. It is found that the RMC method can provide the importance function distributions, required for importance sampling, with accuracy that is suitable for an efficient solution of the deep-penetration problems considered. The use of the RMC method improved, by one to three orders of magnitude, the solution efficiency of the two deep-penetration problems considered: a concrete shield problem and a Tokamak major penetration problem. 8 figures, 4 tables

  19. Inverse Problems and Uncertainty Quantification

    KAUST Repository

    Litvinenko, Alexander

    2014-01-06

    In a Bayesian setting, inverse problems and uncertainty quantification (UQ) - the propagation of uncertainty through a computational (forward) modelare strongly connected. In the form of conditional expectation the Bayesian update becomes computationally attractive. This is especially the case as together with a functional or spectral approach for the forward UQ there is no need for time- consuming and slowly convergent Monte Carlo sampling. The developed sampling- free non-linear Bayesian update is derived from the variational problem associated with conditional expectation. This formulation in general calls for further discretisa- tion to make the computation possible, and we choose a polynomial approximation. After giving details on the actual computation in the framework of functional or spectral approximations, we demonstrate the workings of the algorithm on a number of examples of increasing complexity. At last, we compare the linear and quadratic Bayesian update on the small but taxing example of the chaotic Lorenz 84 model, where we experiment with the influence of different observation or measurement operators on the update.

  20. Inverse Problems and Uncertainty Quantification

    KAUST Repository

    Litvinenko, Alexander; Matthies, Hermann G.

    2014-01-01

    In a Bayesian setting, inverse problems and uncertainty quantification (UQ) - the propagation of uncertainty through a computational (forward) modelare strongly connected. In the form of conditional expectation the Bayesian update becomes computationally attractive. This is especially the case as together with a functional or spectral approach for the forward UQ there is no need for time- consuming and slowly convergent Monte Carlo sampling. The developed sampling- free non-linear Bayesian update is derived from the variational problem associated with conditional expectation. This formulation in general calls for further discretisa- tion to make the computation possible, and we choose a polynomial approximation. After giving details on the actual computation in the framework of functional or spectral approximations, we demonstrate the workings of the algorithm on a number of examples of increasing complexity. At last, we compare the linear and quadratic Bayesian update on the small but taxing example of the chaotic Lorenz 84 model, where we experiment with the influence of different observation or measurement operators on the update.

  1. Inverse problems and uncertainty quantification

    KAUST Repository

    Litvinenko, Alexander

    2013-12-18

    In a Bayesian setting, inverse problems and uncertainty quantification (UQ)— the propagation of uncertainty through a computational (forward) model—are strongly connected. In the form of conditional expectation the Bayesian update becomes computationally attractive. This is especially the case as together with a functional or spectral approach for the forward UQ there is no need for time- consuming and slowly convergent Monte Carlo sampling. The developed sampling- free non-linear Bayesian update is derived from the variational problem associated with conditional expectation. This formulation in general calls for further discretisa- tion to make the computation possible, and we choose a polynomial approximation. After giving details on the actual computation in the framework of functional or spectral approximations, we demonstrate the workings of the algorithm on a number of examples of increasing complexity. At last, we compare the linear and quadratic Bayesian update on the small but taxing example of the chaotic Lorenz 84 model, where we experiment with the influence of different observation or measurement operators on the update.

  2. Including Below Detection Limit Samples in Post Decommissioning Soil Sample Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Hwan; Yim, Man Sung [KAIST, Daejeon (Korea, Republic of)

    2016-05-15

    To meet the required standards the site owner has to show that the soil at the facility has been sufficiently cleaned up. To do this one must know the contamination of the soil at the site prior to clean up. This involves sampling that soil to identify the degree of contamination. However there is a technical difficulty in determining how much decontamination should be done. The problem arises when measured samples are below the detection limit. Regulatory guidelines for site reuse after decommissioning are commonly challenged because the majority of the activity in the soil at or below the limit of detection. Using additional statistical analyses of contaminated soil after decommissioning is expected to have the following advantages: a better and more reliable probabilistic exposure assessment, better economics (lower project costs) and improved communication with the public. This research will develop an approach that defines an acceptable method for demonstrating compliance of decommissioned NPP sites and validates that compliance. Soil samples from NPP often contain censored data. Conventional methods for dealing with censored data sets are statistically biased and limited in their usefulness.

  3. Pigeons, Facebook and the Birthday Problem

    Science.gov (United States)

    Russell, Matthew

    2013-01-01

    The unexpectedness of the birthday problem has long been used by teachers of statistics in discussing basic probability calculation. An activity is described that engages students in understanding probability and sampling using the popular Facebook social networking site. (Contains 2 figures and 1 table.)

  4. Problem Solving and Critical Thinking Skills of Undergraduate Nursing Students

    Directory of Open Access Journals (Sweden)

    Yalçın KANBAY

    2013-12-01

    Full Text Available Due to the fact that critical thinking and problem solving skills are essential components of educational and social lives of individuals, this present study which investigate critical thinking and problem solving skills of undergraduate students of nursing was planned. This is a descriptive study. The study population consisted of undergraduate nursing students of a university during the 2011-2012 academic year. Any specific sampling method was not determined and only the voluntary students was enrolled in the study . Several participants were excluded due to incomplete questionnaires, and eventually a total of 231 nursing students were included in the final sampling. Socio Demographic Features Data Form and the California Critical Thinking Disposition Scale and Problem Solving Inventory were used for data collection. The mean age of 231 subjects (148 girls, 83 boys was 21.34. The mean score of critical thinking was 255.71 for the first-grade, 255.57 for the second-grade, 264.73 for the third-grade, and 256.468 for the forth-grade students. The mean score of critical thinking was determined as 257.41 for the sample, which can be considered as an average value. Although there are mean score differences of critical thinking between the classes , they were not statistically significant (p> 0.05. With regard to the mean score of problem solving, the first-grade students had 92.86, the second-grade students had 94. 29, the third-grade students had 87.00, and the forth-grade students had 92.87. The mean score of problem solving was determined as 92.450 for the sample. Although there are differences between the classes in terms of mean scores of problem solving, it was not found statistically significant (p> 0.05. In this study, statistically significant correlation could not be identified between age and critical thinking skills of the subjects (p>0.05. However, a negative correlation was identified at low levels between critical thinking skills and

  5. Students' errors in solving linear equation word problems: Case ...

    African Journals Online (AJOL)

    The study examined errors students make in solving linear equation word problems with a view to expose the nature of these errors and to make suggestions for classroom teaching. A diagnostic test comprising 10 linear equation word problems, was administered to a sample (n=130) of senior high school first year Home ...

  6. Prediction and Stability of Reading Problems in Middle Childhood

    Science.gov (United States)

    Ritchey, Kristen D.; Silverman, Rebecca D.; Schatschneider, Christopher; Speece, Deborah L.

    2015-01-01

    The longitudinal prediction of reading problems from fourth grade to sixth grade was investigated with a sample of 173 students. Reading problems at the end of sixth grade were defined by significantly below average performance (= 15th percentile) on reading factors defining word reading, fluency, and reading comprehension. Sixth grade poor reader…

  7. Develop of omni-tritium sample preparation device

    International Nuclear Information System (INIS)

    Tian Junhua; Zheng Min; Zhang Dong

    2008-06-01

    The content of total tritium analysis is required in order to know the tritium contaminated degree of biological samples accurately. But the conversion and collection of organic tritium are difficult. A device to treat total tritium samples was developed. Plant samples were treated by combustion and catalysis. After expelling the free HTO in the samples when heated in abundant oxygen, the samples were ignited. Combustion gas passed the catalysts at 800 degree C and its oxidation was catalyzed, and then the combined tritium in tissues was converted into HTO. HTO was collected by water-cooling tube and condenser. For other samples, HTO was treated and collected by high temperature (The highest temperature is 1000 degree C)-catalysis-double condensation method. This device had solved the problem that organic tritium is difficult to gather. (authors)

  8. Perpetrator problem drinking and intimate partner violence ...

    African Journals Online (AJOL)

    IPV) victimization among women and its correlates with perpetrator problem drinking in Cambodia. In the nationally representative cross-sectional 2014 Cambodia Demographic and Health Survey a sample of ever married women aged 15 to ...

  9. A flexible method for multi-level sample size determination

    International Nuclear Information System (INIS)

    Lu, Ming-Shih; Sanborn, J.B.; Teichmann, T.

    1997-01-01

    This paper gives a flexible method to determine sample sizes for both systematic and random error models (this pertains to sampling problems in nuclear safeguard questions). In addition, the method allows different attribute rejection limits. The new method could assist achieving a higher detection probability and enhance inspection effectiveness

  10. Advanced Markov chain Monte Carlo methods learning from past samples

    CERN Document Server

    Liang, Faming; Carrol, Raymond J

    2010-01-01

    This book provides comprehensive coverage of simulation of complex systems using Monte Carlo methods. Developing algorithms that are immune to the local trap problem has long been considered as the most important topic in MCMC research. Various advanced MCMC algorithms which address this problem have been developed include, the modified Gibbs sampler, the methods based on auxiliary variables and the methods making use of past samples. The focus of this book is on the algorithms that make use of past samples. This book includes the multicanonical algorithm, dynamic weighting, dynamically weight

  11. Problem coping skills, psychosocial adversities and mental health problems in children and adolescents as predictors of criminal outcomes in young adulthood.

    Science.gov (United States)

    Aebi, Marcel; Giger, Joël; Plattner, Belinda; Metzke, Christa Winkler; Steinhausen, Hans-Christoph

    2014-05-01

    The purpose of this study was to test child and adolescent psychosocial and psychopathological risk factors as predictors of adult criminal outcomes in a Swiss community sample. In particular, the role of active and avoidant problem coping in youths was analysed. Prevalence rates of young adult crime convictions based on register data were calculated. Univariate and multivariate logistic regressions were used to analyse the prediction of adult criminal convictions 15 years after assessment in a large Swiss community sample of children and adolescents (n = 1,086). Risk factors assessed in childhood and adolescence included socio-economic status (SES), migration background, perceived parental behaviour, familial and other social stressors, coping styles, externalizing and internalizing problems and drug abuse including problematic alcohol consumption. The rate of any young adult conviction was 10.1 %. Besides externalizing problems and problematic alcohol consumption, the presence of any criminal conviction in young adulthood was predicted by low SES and avoidant coping even after controlling for the effects of externalizing problems and problematic alcohol use. The other predictors were significant only when externalizing behaviours and problematic alcohol use were not controlled. In addition to child and adolescent externalizing behaviour problems and substance use, low SES and inadequate problem-solving skills, in terms of avoidant coping, are major risk factors of young adult criminal outcomes and need to be considered in forensic research and criminal prevention programs.

  12. Influence of Solo and Double Parenting on the Adjustment Problems ...

    African Journals Online (AJOL)

    This study investigated the influence of solo and double parenting on the adjustment problems of secondary school adolescents. Adolescents\\' adjustment problems were studied under four groups. These include social, family, personal and academic categories. The sample for the study consisted of 630 adolescents made ...

  13. NAIL SAMPLING TECHNIQUE AND ITS INTERPRETATION

    Directory of Open Access Journals (Sweden)

    TZAR MN

    2011-01-01

    Full Text Available The clinical suspicion of onychomyosis based on appearance of the nails, requires culture for confirmation. This is because treatment requires prolonged use of systemic agents which may cause side effects. One of the common problems encountered is improper nail sampling technique which results in loss of essential information. The unfamiliar terminologies used in reporting culture results may intimidate physicians resulting in misinterpretation and hamper treatment decision. This article provides a simple guide on nail sampling technique and the interpretation of culture results.

  14. The effects of cosmetic surgery on body image, self-esteem, and psychological problems.

    Science.gov (United States)

    von Soest, T; Kvalem, I L; Roald, H E; Skolleborg, K C

    2009-10-01

    This study aims to investigate whether cosmetic surgery has an effect on an individual's body image, general self-esteem, and psychological problems. Further tests were conducted to assess whether the extent of psychological problems before surgery influenced improvements in postoperative psychological outcomes. Questionnaire data from 155 female cosmetic surgery patients from a plastic surgery clinic were obtained before and approximately 6 months after surgery. The questionnaire consisted of measures on body image, self-esteem, and psychological problems. Pre- and postoperative values were compared. Pre- and postoperative measures were also compared with the data compiled from a representative sample of 838 Norwegian women, aged 22-55, with no cosmetic surgery experience. No differences in psychological problems between the presurgery patient and comparison samples were found, whereas differences in body image and self-esteem between the sample groups were reported in an earlier publication. Analyses further revealed an improvement in body image (satisfaction with own appearance) after surgery. A significant but rather small effect on self-esteem was also found, whereas the level of psychological problems did not change after surgery. Postoperative measures of appearance satisfaction, self-esteem, and psychological problems did not differ from values derived from the comparison sample. Finally, few psychological problems before surgery predicted a greater improvement in appearance satisfaction and self-esteem after surgery. The study provides evidence of improvement in satisfaction with own appearance after cosmetic surgery, a variable that is thought to play a central role in understanding the psychology of cosmetic surgery patients. The study also points to the factors that surgeons should be aware of, particularly the role of psychological problems, which could inhibit the positive effects of cosmetic surgery.

  15. Statistical process control charts for attribute data involving very large sample sizes: a review of problems and solutions.

    Science.gov (United States)

    Mohammed, Mohammed A; Panesar, Jagdeep S; Laney, David B; Wilson, Richard

    2013-04-01

    The use of statistical process control (SPC) charts in healthcare is increasing. The primary purpose of SPC is to distinguish between common-cause variation which is attributable to the underlying process, and special-cause variation which is extrinsic to the underlying process. This is important because improvement under common-cause variation requires action on the process, whereas special-cause variation merits an investigation to first find the cause. Nonetheless, when dealing with attribute or count data (eg, number of emergency admissions) involving very large sample sizes, traditional SPC charts often produce tight control limits with most of the data points appearing outside the control limits. This can give a false impression of common and special-cause variation, and potentially misguide the user into taking the wrong actions. Given the growing availability of large datasets from routinely collected databases in healthcare, there is a need to present a review of this problem (which arises because traditional attribute charts only consider within-subgroup variation) and its solutions (which consider within and between-subgroup variation), which involve the use of the well-established measurements chart and the more recently developed attribute charts based on Laney's innovative approach. We close by making some suggestions for practice.

  16. Specific calibration problems for gammaspectrometric measurements of low-level radioactivity in environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, D [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany); Wershofen, H [Physikalisch-Technische Bundesanstalt, Braunschweig (Germany)

    1997-03-01

    Gammaspectrometric measurements of low-level radioactivity in environmental samples are always done in a close source detector geometry. This geometry causes coincidence-summing effects for measurements of multi-photon emitting nuclides. The measurements of radioactivity in environmental samples are also influenced by the absorption of photons in the materials which have to be analysed. Both effects must be taken into account by correction factors with respect to an energy-specific calibration of the detector system for a given geometry and a given composition of the calibration source. The importance of these corrections is emphasized. It is the aim of the present paper to compare different experimental and theoretical methods for the determination of these correction factors published by various authors and to report about efforts to refine them. (orig.)

  17. The four Es of problem gambling: a psychological measure of risk.

    Science.gov (United States)

    Rockloff, Matthew J; Dyer, Victoria

    2006-01-01

    A focus group of Reno area Gamblers Anonymous members identified four psychological traits contributing to risk for problem gambling, including: Escape, Esteem, Excess and Excitement. A panel of four experts authored 240 Likert-type items to measure these traits. By design, none of the items explicitly referred to gambling activities. Study 1 narrowed the field of useful items by employing a quasi-experimental design which compared the answers of Reno area Gamblers Anonymous members (N = 39) to a control sample (N = 34). Study 2 submitted successful items, plus new items authored with the knowledge gained from Study 1, to validation in a random sample telephone survey across Queensland, Australia (N=2577). The final 40 item Four Es scale (4Es) was reliable (alpha=.90); predicted gambling problems as measured by the Canadian Problem Gambling Index of Severity (PGSI, Ferris & Wynne (2001). The Canadian Problem Gambling Index: Final Report: Canadian Centre on Substance Abuse); and distinguished problem gamblers from persons with alcohol abuse problems. The new scale can provide a basis for further study in harm minimization, treatment, and theory development.

  18. The Effectiveness of Problem Based Learning (PBL on Intermediate Financial Accounting Subject

    Directory of Open Access Journals (Sweden)

    Nunuk Suryanti

    2016-12-01

    Full Text Available This research aims to know the effectiveness of Problem Based Learning (PBL Model comparing to Drill Model on Intermediate Financial Accounting subject. The research was a quasi-experimental research. Population was four classes of Accounting Education students in the year of 2014/2015 at Faculty of Educational Science and Teaching of Riau Islamic University (UIR. Sample was taken by using purposive sampling. Then, it used Problem Based Learning (PBL at experimental class and Drill Model at controlled class. Data was collected by using interview, observation, and tests (pre-test and post-test. Moreover, data were analyzed by using independent sample test. Findings show that there is no any difference of learning outcomes between students who taught by Problem Based Learning (PBL Model and Drill Model on Intermediate Financial Accounting.

  19. An improved correlated sampling method for calculating correction factor of detector

    International Nuclear Information System (INIS)

    Wu Zhen; Li Junli; Cheng Jianping

    2006-01-01

    In the case of a small size detector lying inside a bulk of medium, there are two problems in the correction factors calculation of the detectors. One is that the detector is too small for the particles to arrive at and collide in; the other is that the ratio of two quantities is not accurate enough. The method discussed in this paper, which combines correlated sampling with modified particle collision auto-importance sampling, and has been realized on the MCNP-4C platform, can solve these two problems. Besides, other 3 variance reduction techniques are also combined with correlated sampling respectively to calculate a simple calculating model of the correction factors of detectors. The results prove that, although all the variance reduction techniques combined with correlated sampling can improve the calculating efficiency, the method combining the modified particle collision auto-importance sampling with the correlated sampling is the most efficient one. (authors)

  20. Ethnic differences in problem perception and perceived need for care for young children with problem behaviour.

    Science.gov (United States)

    Bevaart, Floor; Mieloo, Cathelijne L; Jansen, Wilma; Raat, Hein; Donker, Marianne C H; Verhulst, Frank C; van Oort, Floor V A

    2012-10-01

    Problem perception and perceived need for professional care are important determinants that can contribute to ethnic differences in the use of mental health care. Therefore, we studied ethnic differences in problem perception and perceived need for professional care in the parents and teachers of 5- to 6-year-old children from the general population who were selected for having emotional and behavioural problems. A cross-sectional study with data of 10,951 children from grade two of the elementary schools in the Rotterdam-Rijnmond area, The Netherlands. Parents and teachers completed the strengths and difficulties questionnaire (SDQ) as well as questions on problem perception and perceived need for care. The SDQ was used to identify children with emotional and behavioural problems. We included Dutch, Surinamese, Antillean, Moroccan and Turkish children in our sample with high (>P90) SDQ scores (N = 1,215), who were not currently receiving professional care for their problems. Amongst children with high SDQ scores, problem perception was lower in non-Dutch parents than in Dutch parents (49% vs. 81%, p ethnic differences were found in parental perceived need and in problem perception and perceived need reported by teachers. Higher levels of problem perception and perceived need were reported by teachers than by parents in all ethnic groups (PP: 87% vs. 63% and PN: 48% vs. 23%). Child health professionals should be aware of ethnic variations in problem perception as low problem perception in parents of non-Dutch children may lead to miscommunication and unmet need for professional care for the child. © 2012 The Authors. Journal of Child Psychology and Psychiatry © 2012 Association for Child and Adolescent Mental Health.

  1. Inverse Problems in a Bayesian Setting

    KAUST Repository

    Matthies, Hermann G.

    2016-02-13

    In a Bayesian setting, inverse problems and uncertainty quantification (UQ)—the propagation of uncertainty through a computational (forward) model—are strongly connected. In the form of conditional expectation the Bayesian update becomes computationally attractive. We give a detailed account of this approach via conditional approximation, various approximations, and the construction of filters. Together with a functional or spectral approach for the forward UQ there is no need for time-consuming and slowly convergent Monte Carlo sampling. The developed sampling-free non-linear Bayesian update in form of a filter is derived from the variational problem associated with conditional expectation. This formulation in general calls for further discretisation to make the computation possible, and we choose a polynomial approximation. After giving details on the actual computation in the framework of functional or spectral approximations, we demonstrate the workings of the algorithm on a number of examples of increasing complexity. At last, we compare the linear and nonlinear Bayesian update in form of a filter on some examples.

  2. Inverse Problems in a Bayesian Setting

    KAUST Repository

    Matthies, Hermann G.; Zander, Elmar; Rosić, Bojana V.; Litvinenko, Alexander; Pajonk, Oliver

    2016-01-01

    In a Bayesian setting, inverse problems and uncertainty quantification (UQ)—the propagation of uncertainty through a computational (forward) model—are strongly connected. In the form of conditional expectation the Bayesian update becomes computationally attractive. We give a detailed account of this approach via conditional approximation, various approximations, and the construction of filters. Together with a functional or spectral approach for the forward UQ there is no need for time-consuming and slowly convergent Monte Carlo sampling. The developed sampling-free non-linear Bayesian update in form of a filter is derived from the variational problem associated with conditional expectation. This formulation in general calls for further discretisation to make the computation possible, and we choose a polynomial approximation. After giving details on the actual computation in the framework of functional or spectral approximations, we demonstrate the workings of the algorithm on a number of examples of increasing complexity. At last, we compare the linear and nonlinear Bayesian update in form of a filter on some examples.

  3. A novel heterogeneous training sample selection method on space-time adaptive processing

    Science.gov (United States)

    Wang, Qiang; Zhang, Yongshun; Guo, Yiduo

    2018-04-01

    The performance of ground target detection about space-time adaptive processing (STAP) decreases when non-homogeneity of clutter power is caused because of training samples contaminated by target-like signals. In order to solve this problem, a novel nonhomogeneous training sample selection method based on sample similarity is proposed, which converts the training sample selection into a convex optimization problem. Firstly, the existing deficiencies on the sample selection using generalized inner product (GIP) are analyzed. Secondly, the similarities of different training samples are obtained by calculating mean-hausdorff distance so as to reject the contaminated training samples. Thirdly, cell under test (CUT) and the residual training samples are projected into the orthogonal subspace of the target in the CUT, and mean-hausdorff distances between the projected CUT and training samples are calculated. Fourthly, the distances are sorted in order of value and the training samples which have the bigger value are selective preference to realize the reduced-dimension. Finally, simulation results with Mountain-Top data verify the effectiveness of the proposed method.

  4. Direct analysis of 210Pb in sediment samples: Self-absorption corrections

    International Nuclear Information System (INIS)

    Cutshall, N.H.; Larsen, I.L.; Olsen, C.R.

    1983-01-01

    A procedure for the direct #betta#-ray instrumental analysis of 210 Pb in sediment samples is presented. The problem of dependence of self-absorption on sample composition is solved by making a direct transmission measurement on each sample. The procedure has been verified by intercalibrations and other tests. (orig.)

  5. Application of the Tripartite Model to a Complicated Sample of Residential Youth with Externalizing Problems

    Science.gov (United States)

    Chin, Eu Gene; Ebesutani, Chad; Young, John

    2013-01-01

    The tripartite model of anxiety and depression has received strong support among child and adolescent populations. Clinical samples of children and adolescents in these studies, however, have usually been referred for treatment of anxiety and depression. This study investigated the fit of the tripartite model with a complicated sample of…

  6. Gambling behaviors and psychopathology related to Attention-Deficit/Hyperactivity Disorder (ADHD) in problem and non-problem adult gamblers.

    Science.gov (United States)

    Fatseas, Melina; Alexandre, Jean-Marc; Vénisse, Jean-Luc; Romo, Lucia; Valleur, Marc; Magalon, David; Chéreau-Boudet, Isabelle; Luquiens, Amandine; Guilleux, Alice; Groupe Jeu; Challet-Bouju, Gaëlle; Grall-Bronnec, Marie

    2016-05-30

    Previous studies showed that Pathological Gambling and Attention Deficit/Hyperactivity Disorder (ADHD) often co-occur. The aim of this study was to examine whether ADHD is associated with specific severity patterns in terms of gambling behavior, psychopathology and personality traits. 599 problem and non-problem-gamblers were recruited in addiction clinics and gambling places in France. Subjects were assessed with the Wender-Utah Rating Scale-Child, the Adult ADHD Self-Report Scale, the Mini International Neuropsychiatric Interview, the Temperament and Character Inventory, the South Oaks Gambling Screen and questionnaires assessing gambling related cognitive distortions and gambling habits. 20.7% (n=124) of gamblers were screened positive for lifetime or current ADHD. Results from the multivariate analysis showed that ADHD was associated with a higher severity of gambling-related problems and with more psychiatric comorbidity. Among problem gamblers, subjects with history of ADHD were also at higher risk for unemployment, psychiatric comorbidity and specific dysfunctional personality traits. This study supports the link between gambling related problems and ADHD in a large sample of problem and non-problem gamblers, including problem-gamblers not seeking treatment. This points out the necessity to consider this disorder in the prevention and in the treatment of pathological gambling. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  7. Witness sample preparation for measuring antireflection coatings.

    Science.gov (United States)

    Willey, Ronald R

    2014-02-01

    Measurement of antireflection coating of witness samples from across the worldwide industry has been shown to have excess variability from a sampling taken for the OSA Topical Meeting on Optical Interference Coatings: Measurement Problem. Various sample preparation techniques have been discussed with their limitations, and a preferred technique is recommended with its justification, calibration procedures, and limitations. The common practice of grinding the second side to reduce its reflection is less than satisfactory. One recommended practice is to paint the polished second side, which reduces its reflection to almost zero. A method to evaluate the suitability of given paints is also described.

  8. Generation of complementary sampled phase-only holograms.

    Science.gov (United States)

    Tsang, P W M; Chow, Y T; Poon, T-C

    2016-10-03

    If an image is uniformly down-sampled into a sparse form and converted into a hologram, the phase component alone will be adequate to reconstruct the image. However, the appearance of the reconstructed image is degraded with numerous empty holes. In this paper, we present a low complexity and non-iterative solution to this problem. Briefly, two phase-only holograms are generated for an image, each based on a different down-sampling lattice. Subsequently, the holograms are displayed alternately at high frame rate. The reconstructed images of the 2 holograms will appear to be a single, densely sampled image with enhance visual quality.

  9. Electrical discharge machining for vessel sample removal

    International Nuclear Information System (INIS)

    Litka, T.J.

    1993-01-01

    Due to aging-related problems or essential metallurgy information (plant-life extension or decommissioning) of nuclear plants, sample removal from vessels may be required as part of an examination. Vessel or cladding samples with cracks may be removed to determine the cause of cracking. Vessel weld samples may be removed to determine the weld metallurgy. In all cases, an engineering analysis must be done prior to sample removal to determine the vessel's integrity upon sample removal. Electrical discharge machining (EDM) is being used for in-vessel nuclear power plant vessel sampling. Machining operations in reactor coolant system (RCS) components must be accomplished while collecting machining chips that could cause damage if they become part of the flow stream. The debris from EDM is a fine talclike particulate (no chips), which can be collected by flushing and filtration

  10. Standard practice for sampling special nuclear materials in multi-container lots

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1987-01-01

    1.1 This practice provides an aid in designing a sampling and analysis plan for the purpose of minimizing random error in the measurement of the amount of nuclear material in a lot consisting of several containers. The problem addressed is the selection of the number of containers to be sampled, the number of samples to be taken from each sampled container, and the number of aliquot analyses to be performed on each sample. 1.2 This practice provides examples for application as well as the necessary development for understanding the statistics involved. The uniqueness of most situations does not allow presentation of step-by-step procedures for designing sampling plans. It is recommended that a statistician experienced in materials sampling be consulted when developing such plans. 1.3 The values stated in SI units are to be regarded as the standard. 1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standar...

  11. Optimizing the triple-axis spectrometer PANDA at the MLZ for small samples and complex sample environment conditions

    Science.gov (United States)

    Utschick, C.; Skoulatos, M.; Schneidewind, A.; Böni, P.

    2016-11-01

    The cold-neutron triple-axis spectrometer PANDA at the neutron source FRM II has been serving an international user community studying condensed matter physics problems. We report on a new setup, improving the signal-to-noise ratio for small samples and pressure cell setups. Analytical and numerical Monte Carlo methods are used for the optimization of elliptic and parabolic focusing guides. They are placed between the monochromator and sample positions, and the flux at the sample is compared to the one achieved by standard monochromator focusing techniques. A 25 times smaller spot size is achieved, associated with a factor of 2 increased intensity, within the same divergence limits, ± 2 ° . This optional neutron focusing guide shall establish a top-class spectrometer for studying novel exotic properties of matter in combination with more stringent sample environment conditions such as extreme pressures associated with small sample sizes.

  12. Predictors of social anxiety in an opioid dependent sample and a control sample

    OpenAIRE

    Shand, Fiona L.; Degenhardt, Louisa; Nelson, Elliot C.; Mattick, Richard P.

    2010-01-01

    Compared to other mental health problems, social anxiety is under-acknowledged amongst opioid dependent populations. This study aimed to assess levels of social anxiety and identify its predictors in an opioid dependent sample and a matched control group. Opioid dependent participants (n = 1385) and controls (n = 417) completed the Social Interaction Anxiety Scale (SIAS), the Social Phobia Scale (SPS) and a diagnostic interview. Regression analyses were used to test a range of predictors of s...

  13. Early Predictors of Eating Problems in Preadolescence

    DEFF Research Database (Denmark)

    Munkholm, Anja; Olsen, Else Marie; Rask, Charlotte Ulrikka

    2016-01-01

    Purpose: The epidemiology of childhood eating problems is far from being fully described. The present study aims to explore early predictors of eating behavior problems in preadolescence. Methods: The study sample comprised 1,939 children from the birth cohort study, the Copenhagen Child Cohort...... interval [CI] = 1.13–6.77; p = .03), with overweight at age 11–12 years and low annual household income as strong explanatory factors (OR = 4.79; 95% CI = 2.81–8.17; p early child...

  14. An optimal maintenance policy for machine replacement problem using dynamic programming

    OpenAIRE

    Mohsen Sadegh Amalnik; Morteza Pourgharibshahi

    2017-01-01

    In this article, we present an acceptance sampling plan for machine replacement problem based on the backward dynamic programming model. Discount dynamic programming is used to solve a two-state machine replacement problem. We plan to design a model for maintenance by consid-ering the quality of the item produced. The purpose of the proposed model is to determine the optimal threshold policy for maintenance in a finite time horizon. We create a decision tree based on a sequential sampling inc...

  15. Condition of Health Problems in The District Health Offi ce Parigi Moutong Central Sulawesi Province, Efforts in Response of Health Problem

    Directory of Open Access Journals (Sweden)

    Ahmad Erlan

    2016-01-01

    Full Text Available Background: District Parigi Moutong, Central Sulawesi Province is one of the Regional District Health Problems. Ranking Public Health Development Index Parigi Moutong to the level of Central Sulawesi was ranked 6 out of 9 districts/cities, while at the national level comes out to 320 of 440 districts/cities in Indonesia. The purpose of this study is to provide a picture of the health problems in Parigi Moutong. In more detail the objectives are observed after the implementation of such interventions and Booster Kalakarya prevention efforts in the area of health problems. Methods: The study is qualitative observational study of participatory design. Samples were taken by using purposive sampling to conduct in-depth interviews and document searches. Results: The results of in-depth interviews obtained information of some constraints inthe implementation of health programs, ie no actions/movements that were signifi cant in the response to the problem. Infant mortality in 2012, registered 7 cases. Substitution head of the health center too fast. This happens because the head of the health center has held PTT doctor working period of one year, which resulted in problems in sustainability programs in health centers. Internal monthly meeting at the Department of Health and the District Health Offi ce with the entire health center no. Effort or movement to address the problems associated Regional Health Problems has not be percieved. Conclusions: Implementation of Regional Booster Kalakarya and Health Troubled make changes to the head of health policy by forming groups Conscious Movement IHC and revitalization partnership TBA and midwives who are increasing numbers toddlersweighing scope and aid delivery by health personnel.

  16. New Approach Based on Compressive Sampling for Sample Rate Enhancement in DASs for Low-Cost Sensing Nodes

    Directory of Open Access Journals (Sweden)

    Francesco Bonavolontà

    2014-10-01

    Full Text Available The paper deals with the problem of improving the maximum sample rate of analog-to-digital converters (ADCs included in low cost wireless sensing nodes. To this aim, the authors propose an efficient acquisition strategy based on the combined use of high-resolution time-basis and compressive sampling. In particular, the high-resolution time-basis is adopted to provide a proper sequence of random sampling instants, and a suitable software procedure, based on compressive sampling approach, is exploited to reconstruct the signal of interest from the acquired samples. Thanks to the proposed strategy, the effective sample rate of the reconstructed signal can be as high as the frequency of the considered time-basis, thus significantly improving the inherent ADC sample rate. Several tests are carried out in simulated and real conditions to assess the performance of the proposed acquisition strategy in terms of reconstruction error. In particular, the results obtained in experimental tests with ADC included in actual 8- and 32-bits microcontrollers highlight the possibility of achieving effective sample rate up to 50 times higher than that of the original ADC sample rate.

  17. Quartz analysis in gravimetric sampling

    International Nuclear Information System (INIS)

    Rex, D.A.

    1990-01-01

    An overview of the methods employed in the assessment of quartz exposure is provided. The principles and some of the problems associated with each method is discussed. The methods reviewed include wet chemical methods, X-ray diffraction and infrared absorption of which the latter two methods are deemed appropriate for analysing quartz on personal gravimetric collected samples. The implications of combining area samples collected over a six month period, and performing only a single quartz analysis rather than separate analyses, are considered. Finally, various options open to mines with regard to their involvement with quartz analysis are also briefly discussed. 35 refs., 6 figs., 1 tab

  18. Probability Sampling Method for a Hidden Population Using Respondent-Driven Sampling: Simulation for Cancer Survivors.

    Science.gov (United States)

    Jung, Minsoo

    2015-01-01

    When there is no sampling frame within a certain group or the group is concerned that making its population public would bring social stigma, we say the population is hidden. It is difficult to approach this kind of population survey-methodologically because the response rate is low and its members are not quite honest with their responses when probability sampling is used. The only alternative known to address the problems caused by previous methods such as snowball sampling is respondent-driven sampling (RDS), which was developed by Heckathorn and his colleagues. RDS is based on a Markov chain, and uses the social network information of the respondent. This characteristic allows for probability sampling when we survey a hidden population. We verified through computer simulation whether RDS can be used on a hidden population of cancer survivors. According to the simulation results of this thesis, the chain-referral sampling of RDS tends to minimize as the sample gets bigger, and it becomes stabilized as the wave progresses. Therefore, it shows that the final sample information can be completely independent from the initial seeds if a certain level of sample size is secured even if the initial seeds were selected through convenient sampling. Thus, RDS can be considered as an alternative which can improve upon both key informant sampling and ethnographic surveys, and it needs to be utilized for various cases domestically as well.

  19. Energy-Aware Path Planning for UAS Persistent Sampling and Surveillance

    Science.gov (United States)

    Shaw-Cortez, Wenceslao

    The focus of this work is to develop an energy-aware path planning algorithm that maximizes UAS endurance, while performing sampling and surveillance missions in a known, stationary wind environment. The energy-aware aspect is specifically tailored to extract energy from the wind to reduce thrust use, thereby increasing aircraft endurance. Wind energy extraction is performed by static soaring and dynamic soaring. Static soaring involves using upward wind currents to increase altitude and potential energy. Dynamic soaring involves taking advantage of wind gradients to exchange potential and kinetic energy. The path planning algorithm developed in this work uses optimization to combine these soaring trajectories with the overarching sampling and surveillance mission. The path planning algorithm uses a simplified aircraft model to tractably optimize soaring trajectories. This aircraft model is presented and along with the derivation of the equations of motion. A nonlinear program is used to create the soaring trajectories based on a given optimization problem. This optimization problem is defined using a heuristic decision tree, which defines appropriate problems given a sampling and surveillance mission and a wind model. Simulations are performed to assess the path planning algorithm. The results are used to identify properties of soaring trajectories as well as to determine what wind conditions support minimal thrust soaring. Additional results show how the path planning algorithm can be tuned between maximizing aircraft endurance and performing the sampling and surveillance mission. A means of trajectory stitching is demonstrated to show how the periodic soaring segments can be combined together to provide a full solution to an infinite/long horizon problem.

  20. Guidance for establishment and implementation of a national sample management program in support of EM environmental sampling and analysis activities

    International Nuclear Information System (INIS)

    1994-01-01

    The role of the National Sample Management Program (NSMP) proposed by the Department of Energy's Office of Environmental Management (EM) is to be a resource for EM programs and for local Field Sample Management Programs (FSMPs). It will be a source of information on sample analysis and data collection within the DOE complex. Therefore the NSMP's primary role is to coordinate and function as a central repository for information collected from the FSMPs. An additional role of the NSMP is to monitor trends in data collected from the FSMPs over time and across sites and laboratories. Tracking these trends will allow identification of potential problems in the sampling and analysis process

  1. CT-scan-monitored electrical resistivity measurements show problems achieving homogeneous saturation

    International Nuclear Information System (INIS)

    Sprunt, E.S.; Coles, M.E.; Davis, R.M.; Muegge, E.L.; Desai, K.P.

    1991-01-01

    X-ray CT scans obtained during measurement of the electrical resistivity of core samples revealed some problems in obtaining uniform saturation along the length of the sample. In this paper the electrical resistivity of core samples is measured as a function of water saturation to determine the saturation exponent, which is used in electric log interpretation. An assumption in such tests is that the water saturation is uniformly distributed. Failure of this assumption can result in errors in the determination of the saturation exponent. Three problems were identified in obtaining homogeneous water saturation in two samples of a Middle Eastern carbonate grainstone. A stationary front formed in one sample at 1 psi oil/brine capillary pressure. A moving front formed at oil/brine capillary pressures of 4 psi or less in both samples tested, in both a fresh mixed-wettability state and in a cleaned water-wet state. In these samples, the heterogeneous fluid distribution caused by a rapidly moving front did not dissipate when the capillary pressure was eliminated

  2. An Improvement to Interval Estimation for Small Samples

    Directory of Open Access Journals (Sweden)

    SUN Hui-Ling

    2017-02-01

    Full Text Available Because it is difficult and complex to determine the probability distribution of small samples,it is improper to use traditional probability theory to process parameter estimation for small samples. Bayes Bootstrap method is always used in the project. Although,the Bayes Bootstrap method has its own limitation,In this article an improvement is given to the Bayes Bootstrap method,This method extended the amount of samples by numerical simulation without changing the circumstances in a small sample of the original sample. And the new method can give the accurate interval estimation for the small samples. Finally,by using the Monte Carlo simulation to model simulation to the specific small sample problems. The effectiveness and practicability of the Improved-Bootstrap method was proved.

  3. Monte Carlo Methods Development and Applications in Conformational Sampling of Proteins

    DEFF Research Database (Denmark)

    Tian, Pengfei

    quantitative insights into their thermodynamic and mechanistic properties that are difficult to probe in laboratory experiments. However, despite the rapid progress in the development of molecular simulation, there are still two limiting factors, (1), the current molecular mechanics force fields alone...... sampling methods to address these two problems. First of all, a novel technique has been developed for reliably estimating diffusion coefficients for use in the enhanced sampling of molecular simulations. A broad applicability of this method is illustrated by studying various simulation problems...

  4. Organizational factors associated with work-related sleep problems in a nationally representative sample of Korean workers.

    Science.gov (United States)

    Park, Jae Bum; Nakata, Akinori; Swanson, Naomi G; Chun, Heekyoung

    2013-02-01

    The purpose of this study was to assess the association of organizational factors with work-related sleep problems (WRSP) among Korean workers. The data were derived from the First Korean Working Conditions Survey conducted in 2006 with a representative sample of the Korean working population (n = 10,039). The overall prevalence of WRSP was 5.1% (95% confidence interval (CI) 4.7-5.5). Those who experienced sexual harassment at work (adjusted odds ratio (aOR) 3.47: 95% CI 1.77-6.81), discrimination due to sex (aOR 2.44: 95% CI 1.36-4.36) or age (aOR 2.22: 95% CI 1.52-3.23), violence at work (aOR 1.98: 95% CI 1.06-3.68), threat of violence (aOR 1.96: 95% CI 1.05-3.66), poor work-life balance (aOR 1.78: 95% CI 1.44-2.20), low job satisfaction (aOR 1.69: 95% CI 1.37-2.09), high cognitive (OR 1.64: 95% CI 1.32-2.03) and emotional (aOR 1.53: 95% CI 1.22-1.91) demands, job insecurity (aOR 1.32: 95% CI 1.07-1.63), and high work intensity (aOR 1.55: 95% CI: 95% CI 1.25-1.92) had an increased risk of WRSP compared to their respective counterparts (p social support was not significantly associated with WRSP (aOR 0.88: 95% CI 0.67-1.15). The results revealed that poor psychosocial working conditions may be related to a high prevalence of WRSP among representative Korean workers.

  5. Trajectories of mental health problems in children of parents with mental health problems: results of the BELLA study.

    Science.gov (United States)

    Plass-Christl, Angela; Otto, Christiane; Klasen, Fionna; Wiegand-Grefe, Silke; Barkmann, Claus; Hölling, Heike; Schulte-Markwort, Michael; Ravens-Sieberer, Ulrike

    2017-11-24

    Children of parents with mental health problems (CPM) have an increased risk for behavioral and psychological problems. This study investigated the age- and gender-specific course as well as predictors of mental health problems in CPM using the longitudinal data (baseline 1- and 2-year follow-ups) of a German general population sample from the BELLA study. Children and adolescents aged 11-17 years (at baseline) who had a parent with mental health problems (n = 325) were analyzed. The mental health problems of the children were assessed by the self-reported version of the strengths and difficulties questionnaire (SDQ). We used individual growth modeling to investigate the age- and gender-specific course, and the effects of risk as well as personal, familial and social protective factors on self-reported mental health problems in CPM. Additionally, data were examined differentiating internalizing and externalizing mental health problems in CPM. Results indicated that female compared to male CPM showed increasing mental health problems with increasing age. Mental health problems in CPM were associated with lower self-efficacy, worse family climate and less social competence over time. Internalizing problems were associated with lower self-efficacy, less social competence and more severe parental mental health problems. Externalizing problems were associated with lower self-efficacy, worse family climate and lower social competence. The main limitations of the study are the short time period (2 years) covered and the report of mental health problems by only one parent. Our findings should be considered in the development of treatment and prevention programs for mental health problems in CPM.

  6. Rating Students' Problem Behaviour: The Role of Teachers' Individual Characteristics

    Science.gov (United States)

    Kokkinos, Constantinos M.; Kargiotidis, Apostolos

    2016-01-01

    This study examined the role of teachers' personal characteristics and mental health status on their frequency ratings of student problem behaviour. A sample of 121 primary school teachers were asked to rate the frequency of a student's behavioural problems, and to self-report their personality traits, psychopathology symptoms and burnout.…

  7. Elementary School Students Perception Levels of Problem Solving Skills

    Science.gov (United States)

    Yavuz, Günes; Yasemin, Deringöl; Arslan, Çigdem

    2017-01-01

    The purpose of this study is to reveal the perception levels of problem solving skills of elementary school students. The sample of the study is formed by totally 264 elementary students attending to 5th, 6th, 7th and 8th grade in a big city in Turkey. Data were collected by means of "Perception Scale for Problem Solving Skills" which…

  8. RF Sub-sampling Receiver Architecture based on Milieu Adapting Techniques

    DEFF Research Database (Denmark)

    Behjou, Nastaran; Larsen, Torben; Jensen, Ole Kiel

    2012-01-01

    A novel sub-sampling based architecture is proposed which has the ability of reducing the problem of image distortion and improving the signal to noise ratio significantly. The technique is based on sensing the environment and adapting the sampling rate of the receiver to the best possible...

  9. Preventing preschool externalizing behavior problems through video-feedback intervention in infancy

    NARCIS (Netherlands)

    Klein Velderman, M.; Bakermans-Kranenburg, M.J.; Juffer, F.; IJzendoorn, M.H. van; Mangelsdorf, S.C.; Zevalkink, D.J.

    2006-01-01

    In the present study (1) intervention effects on children's preschool behavior problems were evaluated in a high risk sample with an overrepresentation of insecure adult attachment representations in 77 first-time mothers, and (2) predictors and correlates of child problem behavior were examined.

  10. Preventing preschool externalizing behavior problems through video-feedback intervention in infancy

    NARCIS (Netherlands)

    Klein Velderman, Mariska; Bakermans-Kranenburg, Marian J; Juffer, Femmie; van IJzendoorn, Marinus H.; Mangelsdorf, Sarah C; Zevalkink, D.J.

    In the present study (1) intervention effects on children's preschool behavior problems were evaluated in a high risk sample with an overrepresentation of insecure adult attachment representations in 77 first-time mothers, and (2) predictors and correlates of child problem behavior were examined.

  11. Mental Health, School Problems, and Social Networks: Modeling Urban Adolescent Substance Use

    Science.gov (United States)

    Mason, Michael J.

    2010-01-01

    This study tested a mediation model of the relationship with school problems, social network quality, and substance use with a primary care sample of 301 urban adolescents. It was theorized that social network quality (level of risk or protection in network) would mediate the effects of school problems, accounting for internalizing problems and…

  12. Machine Learning and Inverse Problem in Geodynamics

    Science.gov (United States)

    Shahnas, M. H.; Yuen, D. A.; Pysklywec, R.

    2017-12-01

    During the past few decades numerical modeling and traditional HPC have been widely deployed in many diverse fields for problem solutions. However, in recent years the rapid emergence of machine learning (ML), a subfield of the artificial intelligence (AI), in many fields of sciences, engineering, and finance seems to mark a turning point in the replacement of traditional modeling procedures with artificial intelligence-based techniques. The study of the circulation in the interior of Earth relies on the study of high pressure mineral physics, geochemistry, and petrology where the number of the mantle parameters is large and the thermoelastic parameters are highly pressure- and temperature-dependent. More complexity arises from the fact that many of these parameters that are incorporated in the numerical models as input parameters are not yet well established. In such complex systems the application of machine learning algorithms can play a valuable role. Our focus in this study is the application of supervised machine learning (SML) algorithms in predicting mantle properties with the emphasis on SML techniques in solving the inverse problem. As a sample problem we focus on the spin transition in ferropericlase and perovskite that may cause slab and plume stagnation at mid-mantle depths. The degree of the stagnation depends on the degree of negative density anomaly at the spin transition zone. The training and testing samples for the machine learning models are produced by the numerical convection models with known magnitudes of density anomaly (as the class labels of the samples). The volume fractions of the stagnated slabs and plumes which can be considered as measures for the degree of stagnation are assigned as sample features. The machine learning models can determine the magnitude of the spin transition-induced density anomalies that can cause flow stagnation at mid-mantle depths. Employing support vector machine (SVM) algorithms we show that SML techniques

  13. Stochastic programming problems with generalized integrated chance constraints

    Czech Academy of Sciences Publication Activity Database

    Branda, Martin

    2012-01-01

    Roč. 61, č. 8 (2012), s. 949-968 ISSN 0233-1934 R&D Projects: GA ČR GAP402/10/1610 Grant - others:SVV(CZ) 261315/2010 Institutional support: RVO:67985556 Keywords : chance constraints * integrated chance constraints * penalty functions * sample approximations * blending problem Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.707, year: 2012 http://library.utia.cas.cz/separaty/2012/E/branda-stochastic programming problems with generalized integrated.pdf

  14. Monte Carlo methods for flux expansion solutions of transport problems

    International Nuclear Information System (INIS)

    Spanier, J.

    1999-01-01

    Adaptive Monte Carlo methods, based on the use of either correlated sampling or importance sampling, to obtain global solutions to certain transport problems have recently been described. The resulting learning algorithms are capable of achieving geometric convergence when applied to the estimation of a finite number of coefficients in a flux expansion representation of the global solution. However, because of the nonphysical nature of the random walk simulations needed to perform importance sampling, conventional transport estimators and source sampling techniques require modification to be used successfully in conjunction with such flux expansion methods. It is shown how these problems can be overcome. First, the traditional path length estimators in wide use in particle transport simulations are generalized to include rather general detector functions (which, in this application, are the individual basis functions chosen for the flus expansion). Second, it is shown how to sample from the signed probabilities that arise as source density functions in these applications, without destroying the zero variance property needed to ensure geometric convergence to zero error

  15. Optimum sample size allocation to minimize cost or maximize power for the two-sample trimmed mean test.

    Science.gov (United States)

    Guo, Jiin-Huarng; Luh, Wei-Ming

    2009-05-01

    When planning a study, sample size determination is one of the most important tasks facing the researcher. The size will depend on the purpose of the study, the cost limitations, and the nature of the data. By specifying the standard deviation ratio and/or the sample size ratio, the present study considers the problem of heterogeneous variances and non-normality for Yuen's two-group test and develops sample size formulas to minimize the total cost or maximize the power of the test. For a given power, the sample size allocation ratio can be manipulated so that the proposed formulas can minimize the total cost, the total sample size, or the sum of total sample size and total cost. On the other hand, for a given total cost, the optimum sample size allocation ratio can maximize the statistical power of the test. After the sample size is determined, the present simulation applies Yuen's test to the sample generated, and then the procedure is validated in terms of Type I errors and power. Simulation results show that the proposed formulas can control Type I errors and achieve the desired power under the various conditions specified. Finally, the implications for determining sample sizes in experimental studies and future research are discussed.

  16. ACTIVE AND PARTICIPATORY METHODS IN BIOLOGY: PROBLEM-SOLVING

    Directory of Open Access Journals (Sweden)

    Adela NEMEŞ

    2010-01-01

    Full Text Available We face with considerable challenge of developing students’ problem solving skills in our difficult environment. Good problem solving skills empower managers in their professional and personal lives. Problem solving skills are valued by academics and employers. The informations in Biology are often presented in abstract forms without contextualisation. Creative problem-solving process involves a few steps, which together provide a structured procedure for identifying challenges, generating ideas and implementing innovative solutions: identifying the problem, searching for possible solutions, selecting the most optimal solution and implementing a possible solution. Each aspect of personality has a different orientation to problem solving, different criteria for judging the effectiveness of the process and different associated strengths. Using real-world data in sample problems will also help facilitate the transfer process, since students can more easily identify with the context of a given situation. The paper describes the use of the Problem-Solving in Biology and the method of its administration. It also presents the results of a study undertaken to evaluate the value in teaching Biology. Problem-solving is seen as an essential skill that is developed in biology education.

  17. Trace aluminium determination and sampling problems of archeological bone employing destructive neutron activation analysis

    International Nuclear Information System (INIS)

    Blotcky, A.J.; Rack, E.P.; Recker, R.R.; Leffler, J.A.; Teitelbaum, S.

    1978-01-01

    A destructive neutron activation analysis procedure was developed for determining trace aluminium content in bone. The method is based on a carefully planned sample preparation, irradiation at a neutron flux for 3.1x10 11 nxcm -2 xs -1 for 5 minutes, and chemical separation based on ion exchange. It was found that bone samples soaked in aluminium containing soil gave highly elevated aluminium values as a result of the aluminium adsorption into the bone matrix. The maximum aluminium content values for prehistoric bones are larger than those of modern bones and comparable to aluminium levels present in bone from renal patients. (T.G.)

  18. Problem-Based Learning Pedagogy Fosters Students' Critical Thinking about Writing

    Science.gov (United States)

    Kumar, Rita; Refaei, Brenda

    2017-01-01

    Convinced of the power of PBL to promote students' critical thinking as demonstrated by its application across disciplines, we designed a series of problems for students in a second-year writing course. We collected samples of their writing before and after implementation of the problems. We were concerned about whether PBL pedagogy would…

  19. Shopping Problems among High School Students

    Science.gov (United States)

    Grant, Jon E.; Potenza, Marc N.; Krishnan-Sarin, Suchitra; Cavallo, Dana A.; Desai, Rani A.

    2010-01-01

    Background Although shopping behavior among adolescents is normal, for some the shopping becomes problematic. An assessment of adolescent shopping behavior along a continuum of severity and its relationship to other behaviors and health issues is incompletely understood. Methods A large sample of high school students (n=3999) was examined using a self-report survey with 153 questions concerning demographic characteristics, shopping behaviors, other health behaviors including substance use, and functioning variables such as grades and violent behavior. Results The overall prevalence of problem shopping was 3.5% (95%CI: 2.93–4.07). Regular smoking, marijuana and other drug use, sadness and hopelessness, and antisocial behaviors (e.g., fighting, carrying weapons) were associated with problem shopping behavior in both boys and girls. Heavy alcohol use was significantly associated with problem shopping only in girls. Conclusion Problem shopping appears fairly common among high school students and is associated with symptoms of depression and a range of potentially addictive and antisocial behaviors. Significant distress and diminished behavioral control suggest that excessive shopping may often have significant associated morbidity. Additional research is needed to develop specific prevention and treatment strategies for adolescents who report problems with shopping. PMID:21497217

  20. Shopping problems among high school students.

    Science.gov (United States)

    Grant, Jon E; Potenza, Marc N; Krishnan-Sarin, Suchitra; Cavallo, Dana A; Desai, Rani A

    2011-01-01

    Although shopping behavior among adolescents is normal, for some, the shopping becomes problematic. An assessment of adolescent shopping behavior along a continuum of severity and its relationship to other behaviors and health issues is incompletely understood. A large sample of high school students (n = 3999) was examined using a self-report survey with 153 questions concerning demographic characteristics, shopping behaviors, other health behaviors including substance use, and functioning variables such as grades and violent behavior. The overall prevalence of problem shopping was 3.5% (95% CI, 2.93-4.07). Regular smoking, marijuana and other drug use, sadness and hopelessness, and antisocial behaviors (e.g., fighting, carrying weapons) were associated with problem shopping behavior in both boys and girls. Heavy alcohol use was significantly associated with problem shopping only in girls. Problem shopping appears fairly common among high school students and is associated with symptoms of depression and a range of potentially addictive and antisocial behaviors. Significant distress and diminished behavioral control suggest that excessive shopping may often have significant associated morbidity. Additional research is needed to develop specific prevention and treatment strategies for adolescents who report problems with shopping. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Relationships between undergraduates' argumentation skills, conceptual quality of problem solutions, and problem solving strategies in introductory physics

    Science.gov (United States)

    Rebello, Carina M.

    This study explored the effects of alternative forms of argumentation on undergraduates' physics solutions in introductory calculus-based physics. A two-phase concurrent mixed methods design was employed to investigate relationships between undergraduates' written argumentation abilities, conceptual quality of problem solutions, as well as approaches and strategies for solving argumentative physics problems across multiple physics topics. Participants were assigned via stratified sampling to one of three conditions (control, guided construct, or guided evaluate) based on gender and pre-test scores on a conceptual instrument. The guided construct and guided evaluate groups received tasks and prompts drawn from literature to facilitate argument construction or evaluation. Using a multiple case study design, with each condition serving as a case, interviews were conducted consisting of a think-aloud problem solving session paired with a semi-structured interview. The analysis of problem solving strategies was guided by the theoretical framework on epistemic games adapted by Tuminaro and Redish (2007). This study provides empirical evidence that integration of written argumentation into physics problems can potentially improve the conceptual quality of solutions, expand their repertoire of problem solving strategies and show promise for addressing the gender gap in physics. The study suggests further avenues for research in this area and implications for designing and implementing argumentation tasks in introductory college physics.

  2. SIPPI: A Matlab toolbox for sampling the solution to inverse problems with complex prior information

    DEFF Research Database (Denmark)

    Hansen, Thomas Mejer; Cordua, Knud Skou; Caroline Looms, Majken

    2013-01-01

    on the solution. The combined states of information (i.e. the solution to the inverse problem) is a probability density function typically referred to as the a posteriori probability density function. We present a generic toolbox for Matlab and Gnu Octave called SIPPI that implements a number of methods...

  3. Improving mathematical problem solving ability through problem-based learning and authentic assessment for the students of Bali State Polytechnic

    Science.gov (United States)

    Darma, I. K.

    2018-01-01

    This research is aimed at determining: 1) the differences of mathematical problem solving ability between the students facilitated with problem-based learning model and conventional learning model, 2) the differences of mathematical problem solving ability between the students facilitated with authentic and conventional assessment model, and 3) interaction effect between learning and assessment model on mathematical problem solving. The research was conducted in Bali State Polytechnic, using the 2x2 experiment factorial design. The samples of this research were 110 students. The data were collected using a theoretically and empirically-validated test. Instruments were validated by using Aiken’s approach of technique content validity and item analysis, and then analyzed using anova stylistic. The result of the analysis shows that the students facilitated with problem-based learning and authentic assessment models get the highest score average compared to the other students, both in the concept understanding and mathematical problem solving. The result of hypothesis test shows that, significantly: 1) there is difference of mathematical problem solving ability between the students facilitated with problem-based learning model and conventional learning model, 2) there is difference of mathematical problem solving ability between the students facilitated with authentic assessment model and conventional assessment model, and 3) there is interaction effect between learning model and assessment model on mathematical problem solving. In order to improve the effectiveness of mathematics learning, collaboration between problem-based learning model and authentic assessment model can be considered as one of learning models in class.

  4. The Effectiveness of Problem Based Learning (PBL) on Intermediate Financial Accounting Subject

    OpenAIRE

    Nunuk Suryanti

    2016-01-01

    This research aims to know the effectiveness of Problem Based Learning (PBL) Model comparing to Drill Model on Intermediate Financial Accounting subject. The research was a quasi-experimental research. Population was four classes of Accounting Education students in the year of 2014/2015 at Faculty of Educational Science and Teaching of Riau Islamic University (UIR). Sample was taken by using purposive sampling. Then, it used Problem Based Learning (PBL) at experimental class and Drill Model a...

  5. Commonalities in the psychological factors associated with problem gambling and Internet dependence.

    Science.gov (United States)

    Dowling, N A; Brown, M

    2010-08-01

    The most commonly applied conceptual approach for excessive Internet use has been as a behavioral addiction, similar to pathological or problem gambling. In order to contribute to the understanding of Internet dependence as a disorder resembling problem gambling, the current study aimed to examine the relationship between problem gambling and Internet dependence and the degree to which psychological factors associated with problem gambling are relevant to the study of Internet dependence. The factors of depression, anxiety, student stressors, loneliness, and social support were examined in a sample of university students from several Australian universities. The findings revealed that there is no overlap between the populations reporting problem gambling and Internet dependence, but that individuals with these disorders report similar psychological profiles. Although requiring replication with larger community samples and longitudinal designs, these preliminary findings suggest that problem gambling and Internet dependence may be separate disorders with common underlying etiologies or consequences. The implications of the findings in relation to the conceptualization and management of these disorders are briefly discussed.

  6. Prevalence of Infertility Problems among Iranian Infertile Patients Referred to Royan Institute.

    Science.gov (United States)

    Sepidarkish, Mahdi; Almasi-Hashiani, Amir; Shokri, Fatemeh; Vesali, Samira; Karimi, Elaheh; Omani Samani, Reza

    2016-01-01

    Few studies have been conducted on the infertility problems in Iran. This study aimed to investigate the prevalence of infertility problems and related factors in Iranian infertile patients. In this cross sectional study, 405 infertile patients referred to Royan Institute, Tehran, Iran, between 2014 and 2015, were selected by simple random sampling. Participants completed the Fertility Problem Inventory (FPI) including 46 questions in five domains (social concern, sexual concern, relationship concern, rejection of parenthood, and need for parenthood). Mean difference between male and female was verified using independent-samples Student's t test. A generalized linear model (GLM) was also used for testing the effect of variables on the fertility problems. Data was analyzed using Stata software version 13. The mean age (SD) of participants was 31.28 (5.42). Our results showed that 160 infertile men (95.23%) were classified as very high prevalence of infertility problems. Among infertile women, 83 patients (35.02%) were as very high prevalence of infertility problems, and 154 patients (64.98%) were as high prevalence. Age (Pmale with lower education level, history of abortion and history of previous treatments failure experienced more infertility problems.

  7. Learning problem-solving skills in a distance education physics course

    Science.gov (United States)

    Rampho, G. J.; Ramorola, M. Z.

    2017-10-01

    In this paper we present the results of a study on the effectiveness of combinations of delivery modes of distance education in learning problem-solving skills in a distance education introductory physics course. A problem-solving instruction with the explicit teaching of a problem-solving strategy and worked-out examples were implemented in the course. The study used the ex post facto research design with stratified sampling to investigate the effect of the learning of a problem-solving strategy on the problem-solving performance. The number of problems attempted and the mean frequency of using a strategy in solving problems in the three course presentation modes were compared. The finding of the study indicated that combining the different course presentation modes had no statistically significant effect in the learning of problem-solving skills in the distance education course.

  8. Explaining the Mind: Problems, Problems

    OpenAIRE

    Harnad, Stevan

    2001-01-01

    The mind/body problem is the feeling/function problem: How and why do feeling systems feel? The problem is not just "hard" but insoluble (unless one is ready to resort to telekinetic dualism). Fortunately, the "easy" problems of cognitive science (such as the how and why of categorization and language) are not insoluble. Five books (by Damasio, Edelman/Tononi...

  9. Variational Approach to Enhanced Sampling and Free Energy Calculations

    Science.gov (United States)

    Valsson, Omar; Parrinello, Michele

    2014-08-01

    The ability of widely used sampling methods, such as molecular dynamics or Monte Carlo simulations, to explore complex free energy landscapes is severely hampered by the presence of kinetic bottlenecks. A large number of solutions have been proposed to alleviate this problem. Many are based on the introduction of a bias potential which is a function of a small number of collective variables. However constructing such a bias is not simple. Here we introduce a functional of the bias potential and an associated variational principle. The bias that minimizes the functional relates in a simple way to the free energy surface. This variational principle can be turned into a practical, efficient, and flexible sampling method. A number of numerical examples are presented which include the determination of a three-dimensional free energy surface. We argue that, beside being numerically advantageous, our variational approach provides a convenient and novel standpoint for looking at the sampling problem.

  10. Perceived Problem-Solving Deficits and Suicidal Ideation: Evidence for the Explanatory Roles of Thwarted Belongingness and Perceived Burdensomeness in Five Samples.

    Science.gov (United States)

    Chu, Carol; Walker, Kristin L; Stanley, Ian H; Hirsch, Jameson K; Greenberg, Jeffrey H; Rudd, M David; Joiner, Thomas E

    2017-06-26

    Perceived social problem-solving deficits are associated with suicide risk; however, little research has examined the mechanisms underlying this relationship. The interpersonal theory of suicide proposes 2 mechanisms in the pathogenesis of suicidal desire: intractable feelings of thwarted belongingness (TB) and perceived burdensomeness (PB). This study tested whether TB and PB serve as explanatory links in the relationship between perceived social problem-solving (SPS) deficits and suicidal thoughts and behaviors cross-sectionally and longitudinally. The specificity of TB and PB was evaluated by testing depression as a rival mediator. Self-report measures of perceived SPS deficits, TB, PB, suicidal ideation, and depression were administered in 5 adult samples: 336 and 105 undergraduates from 2 universities, 53 homeless individuals, 222 primary care patients, and 329 military members. Bias-corrected bootstrap mediation and meta-analyses were conducted to examine the magnitude of the direct and indirect effects, and the proposed mediation paths were tested using zero-inflated negative binomial regressions. Cross-sectionally, TB and PB were significant parallel mediators of the relationship between perceived SPS deficits and ideation, beyond depression. Longitudinally and beyond depression, in 1 study, both TB and PB emerged as significant explanatory factors, and in the other, only PB was a significant mediator. Findings supported the specificity of TB and PB: Depression and SPS deficits were not significant mediators. The relationship between perceived SPS deficits and ideation was explained by interpersonal theory variables, particularly PB. Findings support a novel application of the interpersonal theory, and bolster a growing compendium of literature implicating perceived SPS deficits in suicide risk. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  11. Boosting quantum annealer performance via sample persistence

    Science.gov (United States)

    Karimi, Hamed; Rosenberg, Gili

    2017-07-01

    We propose a novel method for reducing the number of variables in quadratic unconstrained binary optimization problems, using a quantum annealer (or any sampler) to fix the value of a large portion of the variables to values that have a high probability of being optimal. The resulting problems are usually much easier for the quantum annealer to solve, due to their being smaller and consisting of disconnected components. This approach significantly increases the success rate and number of observations of the best known energy value in samples obtained from the quantum annealer, when compared with calling the quantum annealer without using it, even when using fewer annealing cycles. Use of the method results in a considerable improvement in success metrics even for problems with high-precision couplers and biases, which are more challenging for the quantum annealer to solve. The results are further enhanced by applying the method iteratively and combining it with classical pre-processing. We present results for both Chimera graph-structured problems and embedded problems from a real-world application.

  12. A Fast and Accurate Algorithm for l1 Minimization Problems in Compressive Sampling (Preprint)

    Science.gov (United States)

    2013-01-22

    However, updating uk+1 via the formulation of Step 2 in Algorithm 1 can be implemented through the use of the component-wise Gauss - Seidel iteration which...may accelerate the rate of convergence of the algorithm and therefore reduce the total CPU-time consumed. The efficiency of component-wise Gauss - Seidel ...Micchelli, L. Shen, and Y. Xu, A proximity algorithm accelerated by Gauss - Seidel iterations for L1/TV denoising models, Inverse Problems, 28 (2012), p

  13. Laser-induced breakdown spectroscopy for detection of heavy metals in environmental samples

    Science.gov (United States)

    Wisbrun, Richard W.; Schechter, Israel; Niessner, Reinhard; Schroeder, Hartmut

    1993-03-01

    The application of LIBS technology as a sensor for heavy metals in solid environmental samples has been studied. This specific application introduces some new problems in the LIBS analysis. Some of them are related to the particular distribution of contaminants in the grained samples. Other problems are related to mechanical properties of the samples and to general matrix effects, like the water and organic fibers content of the sample. An attempt has been made to optimize the experimental set-up for the various involved parameters. The understanding of these factors has enabled the adjustment of the technique to the substrates of interest. The special importance of the grain size and of the laser-induced aerosol production is pointed out. Calibration plots for the analysis of heavy metals in diverse sand and soil samples have been carried out. The detection limits are shown to be usually below the recent regulation restricted concentrations.

  14. Observer-Based Stabilization of Spacecraft Rendezvous with Variable Sampling and Sensor Nonlinearity

    Directory of Open Access Journals (Sweden)

    Zhuoshi Li

    2013-01-01

    Full Text Available This paper addresses the observer-based control problem of spacecraft rendezvous with nonuniform sampling period. The relative dynamic model is based on the classical Clohessy-Wiltshire equation, and sensor nonlinearity and sampling are considered together in a unified framework. The purpose of this paper is to perform an observer-based controller synthesis by using sampled and saturated output measurements, such that the resulting closed-loop system is exponentially stable. A time-dependent Lyapunov functional is developed which depends on time and the upper bound of the sampling period and also does not grow along the input update times. The controller design problem is solved in terms of the linear matrix inequality method, and the obtained results are less conservative than using the traditional Lyapunov functionals. Finally, a numerical simulation example is built to show the validity of the developed sampled-data control strategy.

  15. A Longitudinal Empirical Investigation of the Pathways Model of Problem Gambling.

    Science.gov (United States)

    Allami, Youssef; Vitaro, Frank; Brendgen, Mara; Carbonneau, René; Lacourse, Éric; Tremblay, Richard E

    2017-12-01

    The pathways model of problem gambling suggests the existence of three developmental pathways to problem gambling, each differentiated by a set of predisposing biopsychosocial characteristics: behaviorally conditioned (BC), emotionally vulnerable (EV), and biologically vulnerable (BV) gamblers. This study examined the empirical validity of the Pathways Model among adolescents followed up to early adulthood. A prospective-longitudinal design was used, thus overcoming limitations of past studies that used concurrent or retrospective designs. Two samples were used: (1) a population sample of French-speaking adolescents (N = 1033) living in low socio-economic status (SES) neighborhoods from the Greater Region of Montreal (Quebec, Canada), and (2) a population sample of adolescents (N = 3017), representative of French-speaking students in Quebec. Only participants with at-risk or problem gambling by mid-adolescence or early adulthood were included in the main analysis (n = 180). Latent Profile Analyses were conducted to identify the optimal number of profiles, in accordance with participants' scores on a set of variables prescribed by the Pathways Model and measured during early adolescence: depression, anxiety, impulsivity, hyperactivity, antisocial/aggressive behavior, and drug problems. A four-profile model fit the data best. Three profiles differed from each other in ways consistent with the Pathways Model (i.e., BC, EV, and BV gamblers). A fourth profile emerged, resembling a combination of EV and BV gamblers. Four profiles of at-risk and problem gamblers were identified. Three of these profiles closely resemble those suggested by the Pathways Model.

  16. Locomotor problems among rural elderly population in a District of Aligarh, North India.

    Science.gov (United States)

    Maroof, Mohd; Ahmad, Anees; Khalique, Najam; Ansari, M Athar

    2017-01-01

    Locomotor functions decline with the age along with other physiological changes. This results in deterioration of the quality of life with decreased social and economic role in the society, as well as increased dependency, for the health care and other basic services. The demographic transition resulting in increased proportion of elderly may pose a burden to the health system. To find the prevalence of locomotor problems among the elderly population, and related sociodemographic factors. The study was a community-based cross-sectional study done at field practice area of Rural Health Training Centre, JN Medical College, AMU, Aligarh, Uttar Pradesh, India. A sample of 225 was drawn from 1018 elderly population aged 60 years and above using systematic random sampling with probability proportionate to size. Sociodemographic characteristics were obtained using pretested and predesigned questionnaire. Locomotor problems were assessed using the criteria used by National Sample Survey Organization. Data were analyzed using SPSS version 20. Chi-square test was used to test relationship of locomotor problems with sociodemographic factors. P locomotor problems among the elderly population was 25.8%. Locomotor problems were significantly associated with age, gender, and working status whereas no significant association with literacy status and marital status was observed. The study concluded that approximately one-fourth of the elderly population suffered from locomotor problems. The sociodemographic factors related to locomotor problems needs to be addressed properly to help them lead an independent and economically productive life.

  17. Sexual orientation, treatment utilization, and barriers for alcohol related problems: Findings from a nationally representative sample.

    Science.gov (United States)

    Allen, Junior Lloyd; Mowbray, Orion

    2016-04-01

    Gay, lesbian, and bisexual (GLB) individuals appear to have an increased likelihood of alcohol use disorders and treatment utilization for alcohol related problems compared to heterosexual individuals. Despite this increase, treatment utilization rates among GLB individuals remain low. In an effort to address this, our paper examined whether or not GLB individuals encounter unique barriers when pursuing treatment for alcohol related problems. Using data from the National Epidemiologic Survey on Alcohol Related Conditions (NESARC), we examined service sector specific factors, some of which included (a) utilization rates, (b) self-reported treatment barriers, and (c) whether or not there were emergent differences among GLB individuals, after controlling for socio-demographic and clinical characteristics. Findings indicated that GLB individuals reported higher severity rates for alcohol use disorders when compared to heterosexual individuals, and were significantly more likely to utilize treatment services for alcohol related problems, however, not across all treatment sectors. While similar patterns were observed when examining barriers to treatment, bisexual individuals reported significantly more barriers than heterosexual and gay/lesbian individuals. These findings underscored the importance of identifying and developing interventions that addresses treatment barriers associated with alcohol use service utilization among GLB populations, and creating improved outreach and education programs to better address stigmas associated with substance use and sexuality. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  18. Problems experienced by people with arthritis when using a computer.

    Science.gov (United States)

    Baker, Nancy A; Rogers, Joan C; Rubinstein, Elaine N; Allaire, Saralynn H; Wasko, Mary Chester

    2009-05-15

    To describe the prevalence of computer use problems experienced by a sample of people with arthritis, and to determine differences in the magnitude of these problems among people with rheumatoid arthritis (RA), osteoarthritis (OA), and fibromyalgia (FM). Subjects were recruited from the Arthritis Network Disease Registry and asked to complete a survey, the Computer Problems Survey, which was developed for this study. Descriptive statistics were calculated for the total sample and the 3 diagnostic subgroups. Ordinal regressions were used to determine differences between the diagnostic subgroups with respect to each equipment item while controlling for confounding demographic variables. A total of 359 respondents completed a survey. Of the 315 respondents who reported using a computer, 84% reported a problem with computer use attributed to their underlying disorder, and approximately 77% reported some discomfort related to computer use. Equipment items most likely to account for problems and discomfort were the chair, keyboard, mouse, and monitor. Of the 3 subgroups, significantly more respondents with FM reported more severe discomfort, more problems, and greater limitations related to computer use than those with RA or OA for all 4 equipment items. Computer use is significantly affected by arthritis. This could limit the ability of a person with arthritis to participate in work and home activities. Further study is warranted to delineate disease-related limitations and develop interventions to reduce them.

  19. A problem-solving routine for improving hospital operations.

    Science.gov (United States)

    Ghosh, Manimay; Sobek Ii, Durward K

    2015-01-01

    The purpose of this paper is to examine empirically why a systematic problem-solving routine can play an important role in the process improvement efforts of hospitals. Data on 18 process improvement cases were collected through semi-structured interviews, reports and other documents, and artifacts associated with the cases. The data were analyzed using a grounded theory approach. Adherence to all the steps of the problem-solving routine correlated to greater degrees of improvement across the sample. Analysis resulted in two models. The first partially explains why hospital workers tended to enact short-term solutions when faced with process-related problems; and tended not seek longer-term solutions that prevent problems from recurring. The second model highlights a set of self-reinforcing behaviors that are more likely to address problem recurrence and result in sustained process improvement. The study was conducted in one hospital setting. Hospital managers can improve patient care and increase operational efficiency by adopting and diffusing problem-solving routines that embody three key characteristics. This paper offers new insights on why caregivers adopt short-term approaches to problem solving. Three characteristics of an effective problem-solving routine in a healthcare setting are proposed.

  20. The Relations of Temperament Reactivity and Effortful Control to Children’s Adjustment Problems in China and the United States

    Science.gov (United States)

    Zhou, Qing; Lengua, Liliana J.; Wang, Yun

    2014-01-01

    The relations of parents’ and teachers’ reports of temperament anger-irritability, positive emotionality, and effortful control (attention focusing and inhibitory control) to children’s externalizing and internalizing problems were examined in Chinese (N = 382) and U.S. (N = 322) samples of school-age children. Results suggested that in both cultures, low effortful control and high anger–irritability were associated with high externalizing problems, although the relations were stronger in the Chinese sample than in the U.S. sample. Low positive emotionality was associated with high internalizing problems in both cultures. However, high positive emotionality was associated with noncomorbid externalizing problems (teachers’ reports) in the Chinese sample but not in the U.S. sample. These findings suggest that there are considerable cross-cultural similarities in the temperament-adjustment associations, although some cross-cultural differences might exist. Implications of the findings for the detection and intervention of adjustment problems in Chinese children are discussed. PMID:19413428

  1. Sampling Assumptions Affect Use of Indirect Negative Evidence in Language Learning.

    Directory of Open Access Journals (Sweden)

    Anne Hsu

    Full Text Available A classic debate in cognitive science revolves around understanding how children learn complex linguistic patterns, such as restrictions on verb alternations and contractions, without negative evidence. Recently, probabilistic models of language learning have been applied to this problem, framing it as a statistical inference from a random sample of sentences. These probabilistic models predict that learners should be sensitive to the way in which sentences are sampled. There are two main types of sampling assumptions that can operate in language learning: strong and weak sampling. Strong sampling, as assumed by probabilistic models, assumes the learning input is drawn from a distribution of grammatical samples from the underlying language and aims to learn this distribution. Thus, under strong sampling, the absence of a sentence construction from the input provides evidence that it has low or zero probability of grammaticality. Weak sampling does not make assumptions about the distribution from which the input is drawn, and thus the absence of a construction from the input as not used as evidence of its ungrammaticality. We demonstrate in a series of artificial language learning experiments that adults can produce behavior consistent with both sets of sampling assumptions, depending on how the learning problem is presented. These results suggest that people use information about the way in which linguistic input is sampled to guide their learning.

  2. Sampling Assumptions Affect Use of Indirect Negative Evidence in Language Learning

    Science.gov (United States)

    2016-01-01

    A classic debate in cognitive science revolves around understanding how children learn complex linguistic patterns, such as restrictions on verb alternations and contractions, without negative evidence. Recently, probabilistic models of language learning have been applied to this problem, framing it as a statistical inference from a random sample of sentences. These probabilistic models predict that learners should be sensitive to the way in which sentences are sampled. There are two main types of sampling assumptions that can operate in language learning: strong and weak sampling. Strong sampling, as assumed by probabilistic models, assumes the learning input is drawn from a distribution of grammatical samples from the underlying language and aims to learn this distribution. Thus, under strong sampling, the absence of a sentence construction from the input provides evidence that it has low or zero probability of grammaticality. Weak sampling does not make assumptions about the distribution from which the input is drawn, and thus the absence of a construction from the input as not used as evidence of its ungrammaticality. We demonstrate in a series of artificial language learning experiments that adults can produce behavior consistent with both sets of sampling assumptions, depending on how the learning problem is presented. These results suggest that people use information about the way in which linguistic input is sampled to guide their learning. PMID:27310576

  3. Problems experienced by older people when opening medicine packaging.

    Science.gov (United States)

    Philbert, Daphne; Notenboom, Kim; Bouvy, Marcel L; van Geffen, Erica C G

    2014-06-01

    Medicine packages can cause problems in daily practice, especially among older people. This study aimed to investigate the prevalence of problems experienced by older people when opening medicine packaging and to investigate how patients manage these problems. A convenience sample of 30 community pharmacies participated in this study. They selected a systematic sample of 30 patients over 65 years old with a recent omeprazole prescription, and a questionnaire was administered by telephone for at least 10 patients per pharmacy. A total of 317 patients completed the questionnaire. They received their omeprazole in a bottle (n = 179, 56.5%), push-through blister pack (n = 102, 32.2%) or peel-off blister pack (n = 36, 11.4%). Some 28.4% of all patients experienced one or more problems with opening their omeprazole packaging; most problems occurred with peel-off blisters (n = 24, 66.7% of all respondents using peel-off blisters), followed by push-through blisters (n = 34, 33.3%) and finally bottles (n = 32, 17.9%). The risk of experiencing problems with peel-off blisters and push-through blisters was higher [relative risk 3.7 (95% confidence interval 2.5-5.5) and 1.9 (1.2-2.8), respectively] than the risk of experiencing problems with opening bottles. Two-thirds of respondents reported management strategies for their problems. Most were found for problems opening bottles (n = 24, 75%), followed by push-through blisters (n = 24, 70.6%) and peel-off blisters (n = 14, 58.3%). One in four patients over 65 experienced difficulties opening their omeprazole packaging and not all of them reported a management strategy for their problems. Manufacturers are advised to pay more attention to the user-friendliness of product packaging. In addition, it is important that pharmacy staff clearly instruct patients on how to open their medicine packaging, or assist them in choosing the most appropriate packaging. © 2013 Royal Pharmaceutical Society.

  4. Assessment of students' critical-thinking and problem-solving abilities across a 6-year doctor of pharmacy program.

    Science.gov (United States)

    Gleason, Brenda L; Gaebelein, Claude J; Grice, Gloria R; Crannage, Andrew J; Weck, Margaret A; Hurd, Peter; Walter, Brenda; Duncan, Wendy

    2013-10-14

    To determine the feasibility of using a validated set of assessment rubrics to assess students' critical-thinking and problem-solving abilities across a doctor of pharmacy (PharmD) curriculum. Trained faculty assessors used validated rubrics to assess student work samples for critical-thinking and problem-solving abilities. Assessment scores were collected and analyzed to determine student achievement of these 2 ability outcomes across the curriculum. Feasibility of the process was evaluated in terms of time and resources used. One hundred sixty-one samples were assessed for critical thinking, and 159 samples were assessed for problem-solving. Rubric scoring allowed assessors to evaluate four 5- to 7-page work samples per hour. The analysis indicated that overall critical-thinking scores improved over the curriculum. Although low yield for problem-solving samples precluded meaningful data analysis, it was informative for identifying potentially needed curricular improvements. Use of assessment rubrics for program ability outcomes was deemed authentic and feasible. Problem-solving was identified as a curricular area that may need improving. This assessment method has great potential to inform continuous quality improvement of a PharmD program.

  5. Self-worth, perceived competence, and behaviour problems in children with cerebral palsy.

    Science.gov (United States)

    Schuengel, Carlo; Voorman, Jeanine; Stolk, Joop; Dallmeijer, Annet; Vermeer, Adri; Becher, Jules

    2006-10-30

    To examine the relevance of physical disabilities for self-worth and perceived competence in children with cerebral palsy (CP), and to examine associations between behaviour problems and self-worth and perceived competence. The Harter scales for self-worth and perceived competence and a new scale for perceived motor competence were used in a sample of 80 children with CP. Their motor functioning was assessed with the Gross Motor Functioning Measure (GMFM) and behaviour problems with the Child Behaviour Check List administered to parents. Self-worth and perceived competence for children with CP were comparable to the Dutch norm sample, except for perceived athletic competence. Within the CP sample, the GMFM showed a domain-specific effect on perceived motor competence. In the multivariate analysis, internalizing problems were associated negatively with all perceived competence scales and self-worth, whereas aggression was positively associated with perceived motor competence, physical appearance, and self-worth. Children with CP appear resilient against challenges posed to their self-worth caused by their disabilities. The relevance of the physical disability appears to be domain-specific. For internalizing problems and aggression, different theoretical models are needed to account for their associations with self-worth and perceived competence.

  6. Environmental sample banking-research and methodology

    International Nuclear Information System (INIS)

    Becker, D.A.

    1976-01-01

    The National Bureau of Standards (NBS), in cooperation with the Environment Protection Agency and the National Science Foundation, is engaged in a research program establishing methodology for environmental sample banking. This program is aimed toward evaluating the feasibility of a National Environment Specimen Bank (NESB). The capability for retrospective chemical analyses to evaluate changes in our environment would provide useful information. Much of this information could not be obtained using data from previously analyzed samples. However, to assure validity for these stored samples, they must be sampled, processed and stored under rigorously evaluated, controlled and documented conditions. The program currently under way in the NBS Analytical Chemistry Division has 3 main components. The first is an extension survey of available literature concerning problems of contamination, losses and storage. The components of interest include trace elements, pesticides, other trace organics (PCBs, plasticizers, etc.), radionuclides and microbiological species. The second component is an experimental evaluation of contamination and losses during sampling and sample handling. Of particular interest here is research into container cleaning methodology for trace elements, with respect to adsorption, desorption, leaching and partial dissolution by various sample matrices. The third component of this program is an evaluation of existing methodology for long-term sample storage

  7. Low-sensitivity H ∞ filter design for linear delta operator systems with sampling time jitter

    Science.gov (United States)

    Guo, Xiang-Gui; Yang, Guang-Hong

    2012-04-01

    This article is concerned with the problem of designing H ∞ filters for a class of linear discrete-time systems with low-sensitivity to sampling time jitter via delta operator approach. Delta-domain model is used to avoid the inherent numerical ill-condition resulting from the use of the standard shift-domain model at high sampling rates. Based on projection lemma in combination with the descriptor system approach often used to solve problems related to delay, a novel bounded real lemma with three slack variables for delta operator systems is presented. A sensitivity approach based on this novel lemma is proposed to mitigate the effects of sampling time jitter on system performance. Then, the problem of designing a low-sensitivity filter can be reduced to a convex optimisation problem. An important consideration in the design of correlation filters is the optimal trade-off between the standard H ∞ criterion and the sensitivity of the transfer function with respect to sampling time jitter. Finally, a numerical example demonstrating the validity of the proposed design method is given.

  8. An Entropic Estimator for Linear Inverse Problems

    Directory of Open Access Journals (Sweden)

    Amos Golan

    2012-05-01

    Full Text Available In this paper we examine an Information-Theoretic method for solving noisy linear inverse estimation problems which encompasses under a single framework a whole class of estimation methods. Under this framework, the prior information about the unknown parameters (when such information exists, and constraints on the parameters can be incorporated in the statement of the problem. The method builds on the basics of the maximum entropy principle and consists of transforming the original problem into an estimation of a probability density on an appropriate space naturally associated with the statement of the problem. This estimation method is generic in the sense that it provides a framework for analyzing non-normal models, it is easy to implement and is suitable for all types of inverse problems such as small and or ill-conditioned, noisy data. First order approximation, large sample properties and convergence in distribution are developed as well. Analytical examples, statistics for model comparisons and evaluations, that are inherent to this method, are discussed and complemented with explicit examples.

  9. Evaluating Housing Problems through Participatory Rural Appraisal ...

    African Journals Online (AJOL)

    Lokoja, a medium sized community in the Middle Belt of Nigeria experienced a massive influx of population in the last twelve years. This study examined housing problems that resulted thereafter. Through a participatory appraisal using group discussion and brainstorming, transect walk and matrix ranking, a sampled ...

  10. Culture and problem-solving: Congruency between the cultural mindset of individualism versus collectivism and problem type.

    Science.gov (United States)

    Arieli, Sharon; Sagiv, Lilach

    2018-06-01

    This research investigates how the cultural mindset influences problem-solving. Drawing on the notion that cultural mindset influences the cognitive process individuals bring to bear at the moment of judgment, we propose that the congruency between the cultural mindset (individualistic vs. collectivistic) and problem type (rule-based vs. context-based) affects success in problem-solving. In 7 studies we incorporated the traditional approach to studying the impact of culture (i.e., comparing cultural groups) with contemporary approaches viewing cultural differences in a more dynamic and malleable manner. We first show that members of an individualistic group (Jewish Americans) perform better on rule-based problems, whereas members of collectivistic groups (ultra-Orthodox Jews and Arabs from Israel) perform better on context-based problems (Study 1). We then study Arabs in Israel using language (Arabic vs. Hebrew) to prime their collectivistic versus individualistic mindsets (Study 2). As hypothesized, among biculturals (those who internalize both cultures) Arabic facilitated solving context-based problems, whereas Hebrew facilitated solving rule-based problems. We follow up with 5 experiments priming the cultural mindset of individualism versus collectivism, employing various manifestations of the cultural dimension: focusing on the individual versus the collective (Studies 3, 6, and 7); experiencing independence versus interdependence (Study 4); and directing attention to objects versus the context (Studies 5a-b). Finally, we took a meta-analytic approach, showing that the effects found in Studies 3-6 are robust across priming tasks, problems, and samples. Taken together, the differences between cultural groups (Studies 1-2) were recreated when the individualistic/collectivistic cultural mindset was primed. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  11. Social problem solving ability predicts mental health among undergraduate students.

    Science.gov (United States)

    Ranjbar, Mansour; Bayani, Ali Asghar; Bayani, Ali

    2013-11-01

    The main objective of this study was predicting student's mental health using social problem solving- ability. In this correlational. descriptive study, 369 (208 female and 161 male) from, Mazandaran University of Medical Science were selected through stratified random sampling method. In order to collect the data, the social problem solving inventory-revised and general health questionnaire were used. Data were analyzed through SPSS-19, Pearson's correlation, t test, and stepwise regression analysis. Data analysis showed significant relationship between social problem solving ability and mental health (P Social problem solving ability was significantly associated with the somatic symptoms, anxiety and insomnia, social dysfunction and severe depression (P social problem solving ability and mental health.

  12. Multi-Factor Policy Evaluation and Selection in the One-Sample Situation

    NARCIS (Netherlands)

    C.M. Chen (Chien-Ming)

    2008-01-01

    textabstractFirms nowadays need to make decisions with fast information obsolesce. In this paper I deal with one class of decision problems in this situation, called the “one-sample” problems: we have finite options and one sample of the multiple criteria with which we use to evaluate those options.

  13. Using lot quality-assurance sampling and area sampling to identify priority areas for trachoma control: Viet Nam.

    Science.gov (United States)

    Myatt, Mark; Mai, Nguyen Phuong; Quynh, Nguyen Quang; Nga, Nguyen Huy; Tai, Ha Huy; Long, Nguyen Hung; Minh, Tran Hung; Limburg, Hans

    2005-10-01

    To report on the use of lot quality-assurance sampling (LQAS) surveys undertaken within an area-sampling framework to identify priority areas for intervention with trachoma control activities in Viet Nam. The LQAS survey method for the rapid assessment of the prevalence of active trachoma was adapted for use in Viet Nam with the aim of classifying individual communes by the prevalence of active trachoma among children in primary school. School-based sampling was used; school sites to be sampled were selected using an area-sampling approach. A total of 719 communes in 41 districts in 18 provinces were surveyed. Survey staff found the LQAS survey method both simple and rapid to use after initial problems with area-sampling methods were identified and remedied. The method yielded a finer spatial resolution of prevalence than had been previously achieved in Viet Nam using semiquantitative rapid assessment surveys and multistage cluster-sampled surveys. When used with area-sampling techniques, the LQAS survey method has the potential to form the basis of survey instruments that can be used to efficiently target resources for interventions against active trachoma. With additional work, such methods could provide a generally applicable tool for effective programme planning and for the certification of the elimination of trachoma as a blinding disease.

  14. Alpha Matting with KL-Divergence Based Sparse Sampling.

    Science.gov (United States)

    Karacan, Levent; Erdem, Aykut; Erdem, Erkut

    2017-06-22

    In this paper, we present a new sampling-based alpha matting approach for the accurate estimation of foreground and background layers of an image. Previous sampling-based methods typically rely on certain heuristics in collecting representative samples from known regions, and thus their performance deteriorates if the underlying assumptions are not satisfied. To alleviate this, we take an entirely new approach and formulate sampling as a sparse subset selection problem where we propose to pick a small set of candidate samples that best explains the unknown pixels. Moreover, we describe a new dissimilarity measure for comparing two samples which is based on KLdivergence between the distributions of features extracted in the vicinity of the samples. The proposed framework is general and could be easily extended to video matting by additionally taking temporal information into account in the sampling process. Evaluation on standard benchmark datasets for image and video matting demonstrates that our approach provides more accurate results compared to the state-of-the-art methods.

  15. Problem video game playing is related to emotional distress in adolescents.

    Science.gov (United States)

    Gonzálvez, María T; Espada, José P; Tejeiro, Ricardo

    2017-06-28

    Problem use of video games is an increasing risk behaviour. High exposure of adolescents to video games has been linked to a variety of disorders, but the relationship between problem video game playing and emotional welfare is unknown. The aim of the study is to analyse problem video game playing in a sample of adolescents and to determine whether there are differences between online and offline players, in addition to examining its relationship with anxiety and depressive symptomatology. A sample of adolescents (N = 380) completed self-reports measuring video game use and symptoms of anxiety and depression. We found that 7.4% of females and 30% of males can be considered as playing at problem levels. Online players were almost 12 times more likely to play at high frequency than offline players (χ2 (1, 267) = 72.72, p < .001, OR = 11.63, 95% CI [6.31, 21.43]). Males play more frequently, and play more online (χ2 (1, 267) = 50.85, p < .001, OR = 6.74, 95% CI [3.90, 11.64]), with a clear relationship between problem video game playing and anxiety (r = .24; p < .001). In females, there is a relationship between problem video game playing and depression (r = .19; p < .05). Our findings contribute to a better understanding of the psychological variables involved in problem video game playing. The implementation of strategies is suggested in order to prevent pathological gaming and associated problems.

  16. Monte Carlo method for solving a parabolic problem

    Directory of Open Access Journals (Sweden)

    Tian Yi

    2016-01-01

    Full Text Available In this paper, we present a numerical method based on random sampling for a parabolic problem. This method combines use of the Crank-Nicolson method and Monte Carlo method. In the numerical algorithm, we first discretize governing equations by Crank-Nicolson method, and obtain a large sparse system of linear algebraic equations, then use Monte Carlo method to solve the linear algebraic equations. To illustrate the usefulness of this technique, we apply it to some test problems.

  17. Problem-Solving After Traumatic Brain Injury in Adolescence: Associations With Functional Outcomes.

    Science.gov (United States)

    Wade, Shari L; Cassedy, Amy E; Fulks, Lauren E; Taylor, H Gerry; Stancin, Terry; Kirkwood, Michael W; Yeates, Keith O; Kurowski, Brad G

    2017-08-01

    To examine the association of problem-solving with functioning in youth with traumatic brain injury (TBI). Cross-sectional evaluation of pretreatment data from a randomized controlled trial. Four children's hospitals and 1 general hospital, with level 1 trauma units. Youth, ages 11 to 18 years, who sustained moderate or severe TBI in the last 18 months (N=153). Problem-solving skills were assessed using the Social Problem-Solving Inventory (SPSI) and the Dodge Social Information Processing Short Stories. Everyday functioning was assessed based on a structured clinical interview using the Child and Adolescent Functional Assessment Scale (CAFAS) and via adolescent ratings on the Youth Self Report (YSR). Correlations and multiple regression analyses were used to examine associations among measures. The TBI group endorsed lower levels of maladaptive problem-solving (negative problem orientation, careless/impulsive responding, and avoidant style) and lower levels of rational problem-solving, resulting in higher total problem-solving scores for the TBI group compared with a normative sample (Pproblem-solving composites were associated with overall functioning on the CAFAS, only maladaptive problem-solving (PProblem-solving after TBI differs from normative samples and is associated with functional impairments. The relation of problem-solving deficits after TBI with global functioning merits further investigation, with consideration of the potential effects of problem-solving interventions on functional outcomes. Copyright © 2017 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  18. Sampling and Analysis Plan for White Oak Creek Watershed Remedial Investigation supplemental sampling, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    1996-05-01

    This Sampling and Analysis (SAP) presents the project requirements for proposed soil sampling to support the White Oak Creek Remedial Investigation/Feasibility Study at Oak Ridge National Laboratory. During the Data Quality Objectives process for the project, it was determined that limited surface soils sampling is need to supplement the historical environmental characterization database. The primary driver for the additional sampling is the need to identify potential human health and ecological risks at various sites that have not yet proceeded through a remedial investigation. These sites include Waste Area Grouping (WAG)3, WAG 4, WAG 7, and WAG 9. WAG 4 efforts are limited to nonradiological characterization since recent seep characterization activities at the WAG have defined the radiological problem there

  19. Moonrise: Sampling the South Pole-Aitken Basin to Address Problems of Solar System Significance

    Science.gov (United States)

    Zeigler, R. A.; Jolliff, B. L.; Korotev, R. L.; Shearer, C. K.

    2016-01-01

    A mission to land in the giant South Pole-Aitken (SPA) Basin on the Moon's southern farside and return a sample to Earth for analysis is a high priority for Solar System Science. Such a sample would be used to determine the age of the SPA impact; the chronology of the basin, including the ages of basins and large impacts within SPA, with implications for early Solar System dynamics and the magmatic history of the Moon; the age and composition of volcanic rocks within SPA; the origin of the thorium signature of SPA with implications for the origin of exposed materials and thermal evolution of the Moon; and possibly the magnetization that forms a strong anomaly especially evident in the northern parts of the SPA basin. It is well known from studies of the Apollo regolith that rock fragments found in the regolith form a representative collection of many different rock types delivered to the site by the impact process (Fig. 1). Such samples are well documented to contain a broad suite of materials that reflect both the local major rock formations, as well as some exotic materials from far distant sources. Within the SPA basin, modeling of the impact ejection process indicates that regolith would be dominated by SPA substrate, formed at the time of the SPA basin-forming impact and for the most part moved around by subsequent impacts. Consistent with GRAIL data, the SPA impact likely formed a vast melt body tens of km thick that took perhaps several million years to cool, but that nonetheless represents barely an instant in geologic time that should be readily apparent through integrated geochronologic studies involving multiple chronometers. It is anticipated that a statistically significant number of age determinations would yield not only the age of SPA but also the age of several prominent nearby basins and large craters within SPA. This chronology would provide a contrast to the Imbrium-dominated chronology of the nearside Apollo samples and an independent test of

  20. Sampling design for use by the soil decontamination project

    International Nuclear Information System (INIS)

    Rutherford, D.W.; Stevens, J.R.

    1981-01-01

    This report proposes a general approach to the problem and discusses sampling of soil to map the contaminated area and to provide samples for characterizaton of soil components and contamination. Basic concepts in sample design are reviewed with reference to environmental transuranic studies. Common designs are reviewed and evaluated for use with specific objectives that might be required by the soil decontamination project. Examples of a hierarchial design pilot study and a combined hierarchial and grid study are proposed for the Rocky Flats 903 pad area

  1. Multi-Informant Assessment of Temperament in Children with Externalizing Behavior Problems

    Science.gov (United States)

    Copeland, William; Landry, Kerry; Stanger, Catherine; Hudziak, James J.

    2004-01-01

    We examined the criterion validity of parent and self-report versions of the Junior Temperament and Character Inventory (JTCI) in children with high levels of externalizing problems. The sample included 412 children (206 participants and 206 siblings) participating in a family study of attention and aggressive behavior problems. Criterion validity…

  2. Jocks, gender, race, and adolescent problem drinking.

    Science.gov (United States)

    Miller, Kathleen E; Hoffman, Joseph H; Barnes, Grace M; Farrell, Michael P; Sabo, Don; Melnick, Merrill J

    2003-01-01

    Alcohol remains the drug of choice for many adolescents; however, the nature of the relationship between athletic involvement and alcohol misuse remains ambiguous. In this article, we used a longitudinal sample of over 600 Western New York adolescents and their families to explore the gender-specific and race-specific relationships between identification with the "jock" label and adolescent alcohol consumption, specifically problem drinking. Operationalization of problem drinking included frequency measures of heavy drinking, binge drinking, and social problems related to alcohol (e.g., trouble with family, friends, school officials over drinking). Self-identified adolescent "jocks" were more likely to engage in problem drinking than their non-jock counterparts, even after controlling for gender, age, race, socioeconomic status, physical maturity, social maturity, and frequency of athletic activity. Jock identity was strongly associated with higher binge drinking frequency in Black adolescent girls. This study underscores the need to distinguish between objective and subjective meanings of athletic involvement when assessing the relationship between sport and adolescent health-risk behavior.

  3. Adaptive Sampling of Time Series During Remote Exploration

    Science.gov (United States)

    Thompson, David R.

    2012-01-01

    This work deals with the challenge of online adaptive data collection in a time series. A remote sensor or explorer agent adapts its rate of data collection in order to track anomalous events while obeying constraints on time and power. This problem is challenging because the agent has limited visibility (all its datapoints lie in the past) and limited control (it can only decide when to collect its next datapoint). This problem is treated from an information-theoretic perspective, fitting a probabilistic model to collected data and optimizing the future sampling strategy to maximize information gain. The performance characteristics of stationary and nonstationary Gaussian process models are compared. Self-throttling sensors could benefit environmental sensor networks and monitoring as well as robotic exploration. Explorer agents can improve performance by adjusting their data collection rate, preserving scarce power or bandwidth resources during uninteresting times while fully covering anomalous events of interest. For example, a remote earthquake sensor could conserve power by limiting its measurements during normal conditions and increasing its cadence during rare earthquake events. A similar capability could improve sensor platforms traversing a fixed trajectory, such as an exploration rover transect or a deep space flyby. These agents can adapt observation times to improve sample coverage during moments of rapid change. An adaptive sampling approach couples sensor autonomy, instrument interpretation, and sampling. The challenge is addressed as an active learning problem, which already has extensive theoretical treatment in the statistics and machine learning literature. A statistical Gaussian process (GP) model is employed to guide sample decisions that maximize information gain. Nonsta tion - ary (e.g., time-varying) covariance relationships permit the system to represent and track local anomalies, in contrast with current GP approaches. Most common GP models

  4. Mediation and Moderation of Divorce Effects on Children’s Behavior Problems

    OpenAIRE

    Weaver, Jennifer; Schofield, Thomas

    2014-01-01

    Using data from the NICHD Study of Early Child Care and Youth Development, we examined children’s internalizing and externalizing behavior problems from age 5 to age 15 in relation to whether they had experienced a parental divorce. Children from divorced families had more behavior problems compared with a propensity score-matched sample of children from intact families according to both teachers and mothers. They exhibited more internalizing and externalizing problems at the first assessment...

  5. Psychometric Properties of the Problems Assessment for Substance Using Psychiatric Patients

    OpenAIRE

    Sayed Hadi Sayed Alitabar; Maryam Falahatpisheh; Mojtaba Habibi Asgarabad; Musa Arvin; Ali Sarvestani

    2016-01-01

    Background and Objective: Today, substance use problem is an important and critical problem in the world. This study investigates the psychometric properties of the Problems Assessment for Substance Using Psychiatric Patients (PASUPP).Materials and Methods: Research was descriptive and correlational. The study population consisted of all psychiatry patients with drug addiction in Tehran. The sample consisted of 381 patients (143 women and 238 men) were selected with a multi-stage cluster samp...

  6. Estimation of Finite Population Mean in Multivariate Stratified Sampling under Cost Function Using Goal Programming

    Directory of Open Access Journals (Sweden)

    Atta Ullah

    2014-01-01

    Full Text Available In practical utilization of stratified random sampling scheme, the investigator meets a problem to select a sample that maximizes the precision of a finite population mean under cost constraint. An allocation of sample size becomes complicated when more than one characteristic is observed from each selected unit in a sample. In many real life situations, a linear cost function of a sample size nh is not a good approximation to actual cost of sample survey when traveling cost between selected units in a stratum is significant. In this paper, sample allocation problem in multivariate stratified random sampling with proposed cost function is formulated in integer nonlinear multiobjective mathematical programming. A solution procedure is proposed using extended lexicographic goal programming approach. A numerical example is presented to illustrate the computational details and to compare the efficiency of proposed compromise allocation.

  7. Students’ Mathematical Creative Thinking through Problem Posing Learning

    Science.gov (United States)

    Ulfah, U.; Prabawanto, S.; Jupri, A.

    2017-09-01

    The research aims to investigate the differences in enhancement of students’ mathematical creative thinking ability of those who received problem posing approach assisted by manipulative media and students who received problem posing approach without manipulative media. This study was a quasi experimental research with non-equivalent control group design. Population of this research was third-grade students of a primary school in Bandung city in 2016/2017 academic year. Sample of this research was two classes as experiment class and control class. The instrument used is a test of mathematical creative thinking ability. Based on the results of the research, it is known that the enhancement of the students’ mathematical creative thinking ability of those who received problem posing approach with manipulative media aid is higher than the ability of those who received problem posing approach without manipulative media aid. Students who get learning problem posing learning accustomed in arranging mathematical sentence become matter of story so it can facilitate students to comprehend about story

  8. Optimal experiment design in a filtering context with application to sampled network data

    OpenAIRE

    Singhal, Harsh; Michailidis, George

    2010-01-01

    We examine the problem of optimal design in the context of filtering multiple random walks. Specifically, we define the steady state E-optimal design criterion and show that the underlying optimization problem leads to a second order cone program. The developed methodology is applied to tracking network flow volumes using sampled data, where the design variable corresponds to controlling the sampling rate. The optimal design is numerically compared to a myopic and a naive strategy. Finally, w...

  9. A study of problem behaviors in 10- to 15-year-old biologically related and unrelated international adoptees

    NARCIS (Netherlands)

    E.J.C.G. van den Oord (Edwin); D.I. Boomsma (Dorret); F.C. Verhulst (Frank)

    1994-01-01

    textabstractGenetic and environmental influences on problem behaviors were studied in a sample of international adoptees. Parental ratings of childrens' problem behaviors were obtained with the Child Behavior Checklist (CBCL). The sample (mean age, 12.4 years) comprised a group of biological

  10. A Study of Problem Behaviors in 10- to 15-Year-Old Biologically Related and Unrelated International Adoptees

    NARCIS (Netherlands)

    van den Oord, E.J.C.G.; Boomsma, D.I.; Verhulst, F.C.

    1994-01-01

    Genetic and environmental influences on problem behaviors were studied in a sample of international adoptees. Parental ratings of childrens' problem behaviors were obtained with the Child Behavior Checklist (CBCL). The sample (mean age, 12.4 years) comprised a group of biological siblings (111

  11. USDA Forest Service national protocols for sampling air pollution-sensitive waters

    Science.gov (United States)

    T. J. Sullivan

    2012-01-01

    The first step in designing a surface water sampling program is identifying one or more problems or questions that require information on water quality. Common water quality problems include nutrient enrichment (from a variety of causes), effects of atmospheric deposition (acidification, eutrophication, toxicity), and effects of major disturbances such as fire or pest...

  12. Understanding catastrophizing from a misdirected problem-solving perspective.

    Science.gov (United States)

    Flink, Ida K; Boersma, Katja; MacDonald, Shane; Linton, Steven J

    2012-05-01

    The aim is to explore pain catastrophizing from a problem-solving perspective. The links between catastrophizing, problem framing, and problem-solving behaviour are examined through two possible models of mediation as inferred by two contemporary and complementary theoretical models, the misdirected problem solving model (Eccleston & Crombez, 2007) and the fear-anxiety-avoidance model (Asmundson, Norton, & Vlaeyen, 2004). In this prospective study, a general population sample (n= 173) with perceived problems with spinal pain filled out questionnaires twice; catastrophizing and problem framing were assessed on the first occasion and health care seeking (as a proxy for medically oriented problem solving) was assessed 7 months later. Two different approaches were used to explore whether the data supported any of the proposed models of mediation. First, multiple regressions were used according to traditional recommendations for mediation analyses. Second, a bootstrapping method (n= 1000 bootstrap resamples) was used to explore the significance of the indirect effects in both possible models of mediation. The results verified the concepts included in the misdirected problem solving model. However, the direction of the relations was more in line with the fear-anxiety-avoidance model. More specifically, the mediation analyses provided support for viewing catastrophizing as a mediator of the relation between biomedical problem framing and medically oriented problem-solving behaviour. These findings provide support for viewing catastrophizing from a problem-solving perspective and imply a need to examine and address problem framing and catastrophizing in back pain patients. ©2011 The British Psychological Society.

  13. Longitudinal associations between cyber-bullying perpetration and victimization and problem behavior and mental health problems in young Australians.

    Science.gov (United States)

    Hemphill, Sheryl A; Kotevski, Aneta; Heerde, Jessica A

    2015-02-01

    To investigate associations between Grade 9 and 10 cyber-bullying perpetration and victimization and Grade 11 problem behavior and mental health problems after controlling for risk factors for these outcomes in the analyses. The sample comprised 927 students from Victoria, Australia who completed a modified version of the self-report Communities That Care Youth Survey in Grades 9-11 to report on risk factors, traditional and cyber-bullying perpetration and victimization, problem behavior, and mental health. Complete data on over 650 participants were analyzed. Five per cent of Grade 9 and 10 students reported cyber-bullying perpetration only, 6-8% reported victimization only, and 8-9% both cyber-bullied others and were cyber-bullied. Results showed that cyber-bullying others in Grade 10 was associated with theft in Grade 11, cyber-victimization in Grade 10 was linked with Grade 11 depressive symptoms, and Grade 10 cyber-bullying perpetration and victimization combined predicted Grade 11 school suspension and binge drinking. Prevention approaches that target traditional and cyber-bullying, and established risk factors are necessary. Such multi-faceted programs may also reduce problem behavior and mental health problems.

  14. The Museum Library in the United States: A Sample

    Science.gov (United States)

    Hull, David; Fearnley, Henry D.

    1976-01-01

    A statistical survey was made of the general condition and problems of the museum library, using a questionnaire sent to a random sample of 856 historical, art, science, and other museum libraries. (Author)

  15. Risk-Based Sampling: I Don't Want to Weight in Vain.

    Science.gov (United States)

    Powell, Mark R

    2015-12-01

    Recently, there has been considerable interest in developing risk-based sampling for food safety and animal and plant health for efficient allocation of inspection and surveillance resources. The problem of risk-based sampling allocation presents a challenge similar to financial portfolio analysis. Markowitz (1952) laid the foundation for modern portfolio theory based on mean-variance optimization. However, a persistent challenge in implementing portfolio optimization is the problem of estimation error, leading to false "optimal" portfolios and unstable asset weights. In some cases, portfolio diversification based on simple heuristics (e.g., equal allocation) has better out-of-sample performance than complex portfolio optimization methods due to estimation uncertainty. Even for portfolios with a modest number of assets, the estimation window required for true optimization may imply an implausibly long stationary period. The implications for risk-based sampling are illustrated by a simple simulation model of lot inspection for a small, heterogeneous group of producers. © 2015 Society for Risk Analysis.

  16. Phase retrieval problems in X-ray physics. From modeling to efficient algorithms

    International Nuclear Information System (INIS)

    Homann, Carolin

    2015-01-01

    In phase retrieval problems that occur in imaging by coherent X-ray diffraction, one tries to reconstruct information about a sample of interest from possibly noisy intensity measurements of the wave field traversing the sample. The mathematical formulation of these problems bases on some assumptions. Usually one of them is that the X-ray wave field is generated by a point source. In order to address this very idealized assumption, it is common to perform a data preprocessing step, the so-called empty beam correction. Within this work, we study the validity of this approach by presenting a quantitative error estimate. Moreover, in order to solve these phase retrieval problems, we want to incorporate a priori knowledge about the structure of the noise and the solution into the reconstruction process. For this reason, the application of a problem adapted iteratively regularized Newton-type method becomes particularly attractive. This method includes the solution of a convex minimization problem in each iteration step. We present a method for solving general optimization problems of this form. Our method is a generalization of a commonly used algorithm which makes it efficiently applicable to a wide class of problems. We also proof convergence results and show the performance of our method by numerical examples.

  17. Personality and problem-solving in common mynas (Acridotheres tristis).

    Science.gov (United States)

    Lermite, Françoise; Peneaux, Chloé; Griffin, Andrea S

    2017-01-01

    Animals show consistent individual differences in behaviour across time and/or contexts. Recently, it has been suggested that proactive personality types might also exhibit fast cognitive styles. The speed with which individuals sample environmental cues is one way in which correlations between personality and cognition might arise. Here, we measured a collection of behavioural traits (competitiveness, neophobia, neophilia, task-directed motivation and exploration) in common mynas (Acridotheres tristis) and measured their relationship with problem solving. We predicted that fast solving mynas would interact with (i.e. sample) the problem solving task at higher rates, but also be more competitive, less neophobic, more neophilic, and more exploratory. Mynas that were faster to solve a novel foraging problem were no more competitive around food and no more inclined to take risks. Unexpectedly, these fast-solving mynas had higher rates of interactions with the task, but also displayed lower levels of exploration. It is possible that a negative relation between problem solving and spatial exploration arose as a consequence of how inter-individual variation in exploration was quantified. We discuss the need for greater consensus on how to measure exploratory behaviour before we can advance our understanding of relationships between cognition and personality more effectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Predicting sample lifetimes in creep fracture of heterogeneous materials

    Science.gov (United States)

    Koivisto, Juha; Ovaska, Markus; Miksic, Amandine; Laurson, Lasse; Alava, Mikko J.

    2016-08-01

    Materials flow—under creep or constant loads—and, finally, fail. The prediction of sample lifetimes is an important and highly challenging problem because of the inherently heterogeneous nature of most materials that results in large sample-to-sample lifetime fluctuations, even under the same conditions. We study creep deformation of paper sheets as one heterogeneous material and thus show how to predict lifetimes of individual samples by exploiting the "universal" features in the sample-inherent creep curves, particularly the passage to an accelerating creep rate. Using simulations of a viscoelastic fiber bundle model, we illustrate how deformation localization controls the shape of the creep curve and thus the degree of lifetime predictability.

  19. The Role of Marital Discord and Parenting in Relations between Parental Problem Drinking and Child Adjustment

    Science.gov (United States)

    Keller, Peggy S.; Cummings, E. Mark; Davies, Patrick T.

    2005-01-01

    Background: Research suggests that children exposed to parental drinking problems are at risk for maladjustment. However, the potential impact of drinking problems in a community sample and the processes involved in the relationship between parental drinking and child outcomes have rarely been examined. Method: A community sample of 235 mothers…

  20. Comparing fixed sampling with minimizer sampling when using k-mer indexes to find maximal exact matches.

    Science.gov (United States)

    Almutairy, Meznah; Torng, Eric

    2018-01-01

    Bioinformatics applications and pipelines increasingly use k-mer indexes to search for similar sequences. The major problem with k-mer indexes is that they require lots of memory. Sampling is often used to reduce index size and query time. Most applications use one of two major types of sampling: fixed sampling and minimizer sampling. It is well known that fixed sampling will produce a smaller index, typically by roughly a factor of two, whereas it is generally assumed that minimizer sampling will produce faster query times since query k-mers can also be sampled. However, no direct comparison of fixed and minimizer sampling has been performed to verify these assumptions. We systematically compare fixed and minimizer sampling using the human genome as our database. We use the resulting k-mer indexes for fixed sampling and minimizer sampling to find all maximal exact matches between our database, the human genome, and three separate query sets, the mouse genome, the chimp genome, and an NGS data set. We reach the following conclusions. First, using larger k-mers reduces query time for both fixed sampling and minimizer sampling at a cost of requiring more space. If we use the same k-mer size for both methods, fixed sampling requires typically half as much space whereas minimizer sampling processes queries only slightly faster. If we are allowed to use any k-mer size for each method, then we can choose a k-mer size such that fixed sampling both uses less space and processes queries faster than minimizer sampling. The reason is that although minimizer sampling is able to sample query k-mers, the number of shared k-mer occurrences that must be processed is much larger for minimizer sampling than fixed sampling. In conclusion, we argue that for any application where each shared k-mer occurrence must be processed, fixed sampling is the right sampling method.

  1. Comparing fixed sampling with minimizer sampling when using k-mer indexes to find maximal exact matches.

    Directory of Open Access Journals (Sweden)

    Meznah Almutairy

    Full Text Available Bioinformatics applications and pipelines increasingly use k-mer indexes to search for similar sequences. The major problem with k-mer indexes is that they require lots of memory. Sampling is often used to reduce index size and query time. Most applications use one of two major types of sampling: fixed sampling and minimizer sampling. It is well known that fixed sampling will produce a smaller index, typically by roughly a factor of two, whereas it is generally assumed that minimizer sampling will produce faster query times since query k-mers can also be sampled. However, no direct comparison of fixed and minimizer sampling has been performed to verify these assumptions. We systematically compare fixed and minimizer sampling using the human genome as our database. We use the resulting k-mer indexes for fixed sampling and minimizer sampling to find all maximal exact matches between our database, the human genome, and three separate query sets, the mouse genome, the chimp genome, and an NGS data set. We reach the following conclusions. First, using larger k-mers reduces query time for both fixed sampling and minimizer sampling at a cost of requiring more space. If we use the same k-mer size for both methods, fixed sampling requires typically half as much space whereas minimizer sampling processes queries only slightly faster. If we are allowed to use any k-mer size for each method, then we can choose a k-mer size such that fixed sampling both uses less space and processes queries faster than minimizer sampling. The reason is that although minimizer sampling is able to sample query k-mers, the number of shared k-mer occurrences that must be processed is much larger for minimizer sampling than fixed sampling. In conclusion, we argue that for any application where each shared k-mer occurrence must be processed, fixed sampling is the right sampling method.

  2. Comparing fixed sampling with minimizer sampling when using k-mer indexes to find maximal exact matches

    Science.gov (United States)

    Torng, Eric

    2018-01-01

    Bioinformatics applications and pipelines increasingly use k-mer indexes to search for similar sequences. The major problem with k-mer indexes is that they require lots of memory. Sampling is often used to reduce index size and query time. Most applications use one of two major types of sampling: fixed sampling and minimizer sampling. It is well known that fixed sampling will produce a smaller index, typically by roughly a factor of two, whereas it is generally assumed that minimizer sampling will produce faster query times since query k-mers can also be sampled. However, no direct comparison of fixed and minimizer sampling has been performed to verify these assumptions. We systematically compare fixed and minimizer sampling using the human genome as our database. We use the resulting k-mer indexes for fixed sampling and minimizer sampling to find all maximal exact matches between our database, the human genome, and three separate query sets, the mouse genome, the chimp genome, and an NGS data set. We reach the following conclusions. First, using larger k-mers reduces query time for both fixed sampling and minimizer sampling at a cost of requiring more space. If we use the same k-mer size for both methods, fixed sampling requires typically half as much space whereas minimizer sampling processes queries only slightly faster. If we are allowed to use any k-mer size for each method, then we can choose a k-mer size such that fixed sampling both uses less space and processes queries faster than minimizer sampling. The reason is that although minimizer sampling is able to sample query k-mers, the number of shared k-mer occurrences that must be processed is much larger for minimizer sampling than fixed sampling. In conclusion, we argue that for any application where each shared k-mer occurrence must be processed, fixed sampling is the right sampling method. PMID:29389989

  3. Sampling and chemical analysis of groundwaters from the exploratory boreholes

    International Nuclear Information System (INIS)

    Wittwer, C.

    1986-10-01

    As a part of the Nagra geological investigation programme in northern Switzerland, numerous water samples were taken in the Boettstein, Weiach, Riniken, Schafisheim, Kaisten and Leuggern boreholes to obtain information on the chemistry and residence times of deep groundwaters. This report contains a compilation of hydrochemical data, comments on the individual water sampling actions and an evaluation of sample quality with respect to admixing of drilling fluids. The samples were taken from separate test intervals in the sediments and the crystalline rock. After removal of various types of drilling fluids such as mud as well as fresh water or deionised water during a cleaning phase, the samples were taken at the surface or at depth using pressure vessels. The tracers added to the drilling fluids (uranine, m-TFMBA) as well as the tritium content were used for a quantiative estimation of the content of drilling fluid in the samples (contamination). With a view fo further geochemical modelling, the samples were assessed with reference to the effect of contamination on the results of the chemical analyses. A total of 68 water samples were taken from 53 different intervals: - 27 samples had problem-free cleaning phases and were taken with negligible contamination. - 23 samples were taken under difficult conditions. Problems with hydraulic communication around packers, uncertain origin, inaccuracy as to extent of contamination, presence of cement, possible traces of salt from drilling fluid etc. meant that the analyses could only be used with extreme caution or after additional data-processing. - The analysis results from 18 samples will be disregarded due to significant drilling fluid content or because more reliable data are available for the same test interval. (author)

  4. Influence of early regulatory problems in infants on their development at 12 months: a longitudinal study in a high-risk sample.

    Science.gov (United States)

    Sidor, Anna; Fischer, Cristina; Eickhorst, Andreas; Cierpka, Manfred

    2013-10-12

    This study examined the extent to which regulatory problems in infants at 4 and 6 months influence childhood development at 12 months. The second aim of the study was to examine the influence maternal distress has on 4-month-old children's subsequent development as well as gender differences with regard to regulatory problems and development. 153 mother-child dyads enrolled in the family support research project "Nobody slips through the net" constituted the comparison group. These families faced psychosocial risks (e.g. poverty, excessive demands on the mother, and mental health disorders of the mother, measured with the risk screening instrument Heidelberger Belastungsskala - HBS) and maternal stress, determined with the Parental Stress Index (PSI-SF). The children's developmental levels and possible early regulatory problems were evaluated by means of the Ages and Stages Questionnaires (ASQ) and a German questionnaire assessing problems of excessive crying along with sleeping and feeding difficulties (SFS). A statistically significant but only low, inverse association between excessive crying, whining and sleep problems at 4 and 6 months and the social development of one-year-olds (accounting for 5% and 8% of the variance respectively) was found. Feeding problems had no effect on development. Although regulatory problems in infants were accompanied by increased maternal stress level, these did not serve as a predictor of the child's social development at 12 months. One-year-old girls reached a higher level of development in social and fine motor skills. No gender differences were found with regard to regulatory problems, nor any moderating effect of gender on the relation between regulatory problems and level of development. Our results reinforce existing knowledge pertaining to the transactional association between regulatory problems in infants, maternal distress and dysfunctionality of mother-child interactions. They also provide evidence of a slight but

  5. Optimal sampling plan for clean development mechanism energy efficiency lighting projects

    International Nuclear Information System (INIS)

    Ye, Xianming; Xia, Xiaohua; Zhang, Jiangfeng

    2013-01-01

    Highlights: • A metering cost minimisation model is built to assist the sampling plan for CDM projects. • The model minimises the total metering cost by the determination of optimal sample size. • The required 90/10 criterion sampling accuracy is maintained. • The proposed metering cost minimisation model is applicable to other CDM projects as well. - Abstract: Clean development mechanism (CDM) project developers are always interested in achieving required measurement accuracies with the least metering cost. In this paper, a metering cost minimisation model is proposed for the sampling plan of a specific CDM energy efficiency lighting project. The problem arises from the particular CDM sampling requirement of 90% confidence and 10% precision for the small-scale CDM energy efficiency projects, which is known as the 90/10 criterion. The 90/10 criterion can be met through solving the metering cost minimisation problem. All the lights in the project are classified into different groups according to uncertainties of the lighting energy consumption, which are characterised by their statistical coefficient of variance (CV). Samples from each group are randomly selected to install power meters. These meters include less expensive ones with less functionality and more expensive ones with greater functionality. The metering cost minimisation model will minimise the total metering cost through the determination of the optimal sample size at each group. The 90/10 criterion is formulated as constraints to the metering cost objective. The optimal solution to the minimisation problem will therefore minimise the metering cost whilst meeting the 90/10 criterion, and this is verified by a case study. Relationships between the optimal metering cost and the population sizes of the groups, CV values and the meter equipment cost are further explored in three simulations. The metering cost minimisation model proposed for lighting systems is applicable to other CDM projects as

  6. Bonus algorithm for large scale stochastic nonlinear programming problems

    CERN Document Server

    Diwekar, Urmila

    2015-01-01

    This book presents the details of the BONUS algorithm and its real world applications in areas like sensor placement in large scale drinking water networks, sensor placement in advanced power systems, water management in power systems, and capacity expansion of energy systems. A generalized method for stochastic nonlinear programming based on a sampling based approach for uncertainty analysis and statistical reweighting to obtain probability information is demonstrated in this book. Stochastic optimization problems are difficult to solve since they involve dealing with optimization and uncertainty loops. There are two fundamental approaches used to solve such problems. The first being the decomposition techniques and the second method identifies problem specific structures and transforms the problem into a deterministic nonlinear programming problem. These techniques have significant limitations on either the objective function type or the underlying distributions for the uncertain variables. Moreover, these ...

  7. Parenting stress and child behavior problems among clinic-referred youth: cross-cultural differences across the US and Korea.

    Science.gov (United States)

    Chung, Kyong-Mee; Ebesutani, Chad; Bang, Hye Min; Kim, Joohee; Chorpita, Bruce F; Weisz, John R; Suh, Dongsoo; Byun, Heejung

    2013-06-01

    Due to increased multiculturalism in the US and abroad, there is a need for increased understanding of the different ways in which parenting stress is related to child problems across cultures. In the present study, we investigated (a) differences in reported parenting stress and childhood problem behaviors across a Korean (n = 71) and US (n = 71) sample, as well as (b) differences in the ways in which parenting stress and childhood problems were related across Korean and US children based on mothers' reports. Results revealed that Korean mothers reported significantly higher parenting stress yet significantly lower childhood problem behaviors compared to US mothers. In addition, mother-based reports of child problems were significantly associated with parenting stress in the US sample, but not in the Korean sample. Clinical implications and culturally-relevant issues relevant to these findings are addressed, including a potential under-reporting bias of child problems among Asian parents.

  8. A simple and reliable methodology to detect egg white in art samples

    Indian Academy of Sciences (India)

    2013-04-26

    Apr 26, 2013 ... threshold density values useful for the detection of ovalbumin in samples from ancient works of art. .... slides a mixture of a water solution of dry egg white and the .... ily, facing the problems of sample leakage, background.

  9. Calculation of upper confidence bounds on not-sampled vegetation types using a systematic grid sample: An application to map unit definition for existing vegetation maps

    Science.gov (United States)

    Paul L. Patterson; Mark Finco

    2009-01-01

    This paper explores the information FIA data can produce regarding forest types that were not sampled and develops the equations necessary to define the upper confidence bounds on not-sampled forest types. The problem is reduced to a Bernoulli variable. This simplification allows the upper confidence bounds to be calculated based on Cochran (1977). Examples are...

  10. Children's Problems Predict Adults' "DSM-IV" Disorders across 24 Years

    Science.gov (United States)

    Reef, Joni; van Meurs, Inge; Verhulst, Frank C.; van der Ende, Jan

    2010-01-01

    Objective: The goal of this study was to determine continuities of a broad range of psychopathology from childhood into middle adulthood in a general population sample across a 24-year follow-up. Method: In 1983, parent ratings of children's problems were collected with the Child Behavior Checklist (CBCL) in a general population sample of 2,076…

  11. Path optimization method for the sign problem

    Directory of Open Access Journals (Sweden)

    Ohnishi Akira

    2018-01-01

    Full Text Available We propose a path optimization method (POM to evade the sign problem in the Monte-Carlo calculations for complex actions. Among many approaches to the sign problem, the Lefschetz-thimble path-integral method and the complex Langevin method are promising and extensively discussed. In these methods, real field variables are complexified and the integration manifold is determined by the flow equations or stochastically sampled. When we have singular points of the action or multiple critical points near the original integral surface, however, we have a risk to encounter the residual and global sign problems or the singular drift term problem. One of the ways to avoid the singular points is to optimize the integration path which is designed not to hit the singular points of the Boltzmann weight. By specifying the one-dimensional integration-path as z = t +if(t(f ϵ R and by optimizing f(t to enhance the average phase factor, we demonstrate that we can avoid the sign problem in a one-variable toy model for which the complex Langevin method is found to fail. In this proceedings, we propose POM and discuss how we can avoid the sign problem in a toy model. We also discuss the possibility to utilize the neural network to optimize the path.

  12. Computer Use and Vision‑Related Problems Among University ...

    African Journals Online (AJOL)

    and adjusted OR was calculated using the multiple logistic regression. Results: The ... Nearly 72% of students reported frequent interruption of computer work. Headache ... procedure (non-probability sampling) recruiting 250 .... Table 1: Percentage distribution of visual problems among different genders and ethnic groups.

  13. The Recent Developments in Sample Preparation for Mass Spectrometry-Based Metabolomics.

    Science.gov (United States)

    Gong, Zhi-Gang; Hu, Jing; Wu, Xi; Xu, Yong-Jiang

    2017-07-04

    Metabolomics is a critical member in systems biology. Although great progress has been achieved in metabolomics, there are still some problems in sample preparation, data processing and data interpretation. In this review, we intend to explore the roles, challenges and trends in sample preparation for mass spectrometry- (MS-) based metabolomics. The newly emerged sample preparation methods were also critically examined, including laser microdissection, in vivo sampling, dried blood spot, microwave, ultrasound and enzyme-assisted extraction, as well as microextraction techniques. Finally, we provide some conclusions and perspectives for sample preparation in MS-based metabolomics.

  14. Social Orientation: Problem Behavior and Motivations Toward Interpersonal Problem Solving Among High Risk Adolescents

    Science.gov (United States)

    Kuperminc, Gabriel P.; Allen, Joseph P.

    2006-01-01

    A model of problematic adolescent behavior that expands current theories of social skill deficits in delinquent behavior to consider both social skills and orientation toward the use of adaptive skills was examined in an ethnically and socioeconomically diverse sample of 113 male and female adolescents. Adolescents were selected on the basis of moderate to serious risk for difficulties in social adaptation in order to focus on the population of youth most likely to be targeted by prevention efforts. Structural equation modeling was used to examine cross-sectional data using multiple informants (adolescents, peers, and parents) and multiple methods (performance test and self-report). Adolescent social orientation, as reflected in perceived problem solving effectiveness, identification with adult prosocial values, and self-efficacy expectations, exhibited a direct association to delinquent behavior and an indirect association to drug involvement mediated by demonstrated success in using problem solving skills. Results suggest that the utility of social skill theories of adolescent problem behaviors for informing preventive and remedial interventions can be enhanced by expanding them to consider adolescents’ orientation toward using the skills they may already possess. PMID:16929380

  15. Problems in Staff and Educational Development Leadership: Solving, Framing, and Avoiding

    Science.gov (United States)

    Blackmore, Paul; Wilson, Andrew

    2005-01-01

    Analysis of interviews using critical incident technique with a sample of leaders in staff and educational development in higher education institutions reveals a limited use of classical problem-solving approaches. However, many leaders are able to articulate ways in which they frame problems. Framing has to do with goals, which may be complex,…

  16. Optimal sampling plan for clean development mechanism lighting projects with lamp population decay

    International Nuclear Information System (INIS)

    Ye, Xianming; Xia, Xiaohua; Zhang, Jiangfeng

    2014-01-01

    Highlights: • A metering cost minimisation model is built with the lamp population decay to optimise CDM lighting projects sampling plan. • The model minimises the total metering cost and optimise the annual sample size during the crediting period. • The required 90/10 criterion sampling accuracy is satisfied for each CDM monitoring report. - Abstract: This paper proposes a metering cost minimisation model that minimises metering cost under the constraints of sampling accuracy requirement for clean development mechanism (CDM) energy efficiency (EE) lighting project. Usually small scale (SSC) CDM EE lighting projects expect a crediting period of 10 years given that the lighting population will decay as time goes by. The SSC CDM sampling guideline requires that the monitored key parameters for the carbon emission reduction quantification must satisfy the sampling accuracy of 90% confidence and 10% precision, known as the 90/10 criterion. For the existing registered CDM lighting projects, sample sizes are either decided by professional judgment or by rule-of-thumb without considering any optimisation. Lighting samples are randomly selected and their energy consumptions are monitored continuously by power meters. In this study, the sampling size determination problem is formulated as a metering cost minimisation model by incorporating a linear lighting decay model as given by the CDM guideline AMS-II.J. The 90/10 criterion is formulated as constraints to the metering cost minimisation problem. Optimal solutions to the problem minimise the metering cost whilst satisfying the 90/10 criterion for each reporting period. The proposed metering cost minimisation model is applicable to other CDM lighting projects with different population decay characteristics as well

  17. [Problem-solving strategies and marital satisfaction].

    Science.gov (United States)

    Kriegelewicz, Olga

    2006-01-01

    This study investigated the relation between problem-solving strategies in the marital conflict and marital satisfaction. Four problem-solving strategies (Dialogue, Loyalty, Escalation of conflict and Withdrawal) were measured by the Problem-Solving Strategies Inventory, in two versions: self-report and report of partners' perceived behaviour. This measure refers to the concept of Rusbult, Johnson and Morrow, and meets high standards of reliability (alpha Cronbach from alpha = 0.78 to alpha = 0.94) and validity. Marital satisfaction was measured by Marriage Success Scale. The sample was composed of 147 marital couples. The study revealed that satisfied couples, in comparison with non-satisfied couples, tend to use constructive problem-solving strategies (Dialogue and Loyalty). They rarely use destructive strategies like Escalation of conflict or Withdrawal. Dialogue is the strategy connected with satisfaction in a most positive manner. These might be very important guidelines to couples' psychotherapy. Loyalty to oneself is a significant positive predictor of male satisfaction is also own Loyalty. The study shows that constructive attitudes are the most significant predictors of marriage satisfaction. It is therefore worth concentrating mostly on them in the psychotherapeutic process instead of eliminating destructive attitudes.

  18. English Preservice Teaching: Problems and Suggested Solutions

    Science.gov (United States)

    Naeem, Marwa Ahmed Refat

    2014-01-01

    The present study investigated the problems faced by Egyptian EFL prospective teachers during their first encounter with preservice teaching. The sample for the study included 135 prospective EFL teachers trained in five preparatory (middle) schools in Kafr El-Sheikh city, Egypt. At the end of their first year training course, the prospective…

  19. A direct sampling method for inverse electromagnetic medium scattering

    KAUST Repository

    Ito, Kazufumi; Jin, Bangti; Zou, Jun

    2013-01-01

    In this paper, we study the inverse electromagnetic medium scattering problem of estimating the support and shape of medium scatterers from scattered electric/magnetic near-field data. We shall develop a novel direct sampling method based

  20. A survey of archaeological and geological samples dated in 1990

    International Nuclear Information System (INIS)

    Mejdahl, V.

    1991-01-01

    A survey of dated archaeological and geological samples is given, using thermoluminescence dating. Some of the sediment samples were also dated by means of optically stimulated luminescence (OSL) using a newly developed infrared diode system. In most cases the luminescence dates are in accordance with archaeological and geological estimates. Some discrepancies were found because some feldspar samples exhibited severe anomalous fading. It may be possible to avoid this problem by basing the dating on OSL of quartz. For sediment samples of Eemian or Early Weichselian age severe underestimates were encountered with both methods. The reason might be related to the large difference between the natural dose rate and that used in laboratory irradiations. Traps corresponding to low-temperature peaks such as the 150 deg. C peak in feldspars will remain almost empty under natural conditions, but will fill up to saturation under laboratory irradiation and thereby more charges will be captured in high-temperature traps. As a result, natural growth curves and laboratory produced luminescence growth curves will have different slopes and this will lead to underestimation. This problem might avoided by holding samples at an elevated temperature during laboratory irradiation, thus keeping the low-temperature traps empty. Preliminary experiments where feldspar samples were held at 130 deg. C during irradiation have given promising results. (AB) (31 refs.)

  1. A Variational Approach to Enhanced Sampling and Free Energy Calculations

    Science.gov (United States)

    Parrinello, Michele

    2015-03-01

    The presence of kinetic bottlenecks severely hampers the ability of widely used sampling methods like molecular dynamics or Monte Carlo to explore complex free energy landscapes. One of the most popular methods for addressing this problem is umbrella sampling which is based on the addition of an external bias which helps overcoming the kinetic barriers. The bias potential is usually taken to be a function of a restricted number of collective variables. However constructing the bias is not simple, especially when the number of collective variables increases. Here we introduce a functional of the bias which, when minimized, allows us to recover the free energy. We demonstrate the usefulness and the flexibility of this approach on a number of examples which include the determination of a six dimensional free energy surface. Besides the practical advantages, the existence of such a variational principle allows us to look at the enhanced sampling problem from a rather convenient vantage point.

  2. Systematic adaptive cluster sampling for the assessment of rare tree species in Nepal

    NARCIS (Netherlands)

    Acharya, B.; Bhattarai, G.; Gier, de A.; Stein, A.

    2000-01-01

    Sampling to assess rare tree species poses methodic problems, because they may cluster and many plots with no such trees are to be expected. We used systematic adaptive cluster sampling (SACS) to sample three rare tree species in a forest area of about 40 ha in Nepal. We checked its applicability

  3. GeoGebra Assist Discovery Learning Model for Problem Solving Ability and Attitude toward Mathematics

    Science.gov (United States)

    Murni, V.; Sariyasa, S.; Ardana, I. M.

    2017-09-01

    This study aims to describe the effet of GeoGebra utilization in the discovery learning model on mathematical problem solving ability and students’ attitude toward mathematics. This research was quasi experimental and post-test only control group design was used in this study. The population in this study was 181 of students. The sampling technique used was cluster random sampling, so the sample in this study was 120 students divided into 4 classes, 2 classes for the experimental class and 2 classes for the control class. Data were analyzed by using one way MANOVA. The results of data analysis showed that the utilization of GeoGebra in discovery learning can lead to solving problems and attitudes towards mathematics are better. This is because the presentation of problems using geogebra can assist students in identifying and solving problems and attracting students’ interest because geogebra provides an immediate response process to students. The results of the research are the utilization of geogebra in the discovery learning can be applied in learning and teaching wider subject matter, beside subject matter in this study.

  4. Sleep Problems in Students of Elementary Schools in Kashan in 2013

    Directory of Open Access Journals (Sweden)

    FS Asgarian

    2016-05-01

    Full Text Available Introduction: Sleep problems are taken into account as a prevalent problem within school-age children that is normally ignored in spite of its high prevalence. Therefore, this study aimed to determine the frequency of sleep problems within elementary students in Kashan. Methods: This study is descriptive-cross sectional, in which 300 children (7-12 years old of Kashan elementary schools were randomly selected via cluster sampling method. The study instruments for data collection involved questions concerning children's age and sex as well as BEAR'S questionnaire, which were filled by the children's mothers. Moreover, the study data were analyzed by descriptive statistics method (mean and standard deviation, independent sample T-test was used to compare mean of sleep duration and Mann-Whitney u test was applied to evaluate the difference between age and sex groups. Results: Totally, 300 children participated in this study, among which 44.3% were boys and 55.7% were girls. The most common sleep problems involved nightmare and resistance against a wakening. Relative frequency of awakening during night was observed to be higher within boys than girls (p<0.05. Conclusion: High frequency of sleep problems in the current study may indicate the significance of taking sleep problems into consideration within students as well as informing healthy sleep patterns in order to promote knowledge level of parents via schools and parent-teacher meetings.

  5. Perceived Problems of Being an Accounting Teacher

    Directory of Open Access Journals (Sweden)

    Tamires Sousa Araújo

    2015-04-01

    Full Text Available This study aims to identify the primary problems faced by accounting professors both upon entry into the profession and during later phases. Thus, it seeks to answer the following research question: what are the problems perceived by accounting professors in Brazil during each phase of the professional life cycle? The data collection instrument was constructed based on the life cycles proposed by Huberman (2000 and the problems identified by Veenman (1984 and validated by a committee of experts (Delphi technique. The sample consisted of 574 Brazilian professors. The results indicate that the main problems faced by professors were the following: "lack of student motivation"; "heterogeneous classes"; "amount of administrative work"; "very large class size"; and "lack of time". It was also found that these problems tend to be the same during all phases of the professorial life cycle. However, these problems are more intense upon entry into the career; their importance decreases in each phase. It was also found that professors working for public versus private institutions confronted different problems. The large amount of administrative work and the lack of guidance by the higher education institution (HEI are typical problems of public institutions. The degree level achieved by professors is also sensitive to the type of problems that they face. In other words, the lack of opportunities for additional training, the lack of HEI guidance, and the knowledge of academic standards are issues that most directly affect professors with lower professional degrees, whereas the lack of time and the large amount of administrative work are problems faced with greater intensity by professors with higher degrees.

  6. Constructing squares as a mathematical problem solving process in pre-school

    Directory of Open Access Journals (Sweden)

    MARIA ANGELA SHIAKALLI

    2014-06-01

    Full Text Available Could problem solving be the object of teaching in early education? Could children’s engagement in problem solving processes lead to skills and conceptual understanding development? Could appropriate teaching interventions scaffold children’s efforts? The sample consisted of 25 children attending public pre-school in Cyprus. The children were asked to construct different sized squares. Findings show that children responded positively to the problem and were successful in solving it. During the problem solving process children demonstrated development of skills and conceptual understanding. Teacher-children and children-children interactions played an important role in the positive outcome of the activity.

  7. An efficient method for generalized linear multiplicative programming problem with multiplicative constraints.

    Science.gov (United States)

    Zhao, Yingfeng; Liu, Sanyang

    2016-01-01

    We present a practical branch and bound algorithm for globally solving generalized linear multiplicative programming problem with multiplicative constraints. To solve the problem, a relaxation programming problem which is equivalent to a linear programming is proposed by utilizing a new two-phase relaxation technique. In the algorithm, lower and upper bounds are simultaneously obtained by solving some linear relaxation programming problems. Global convergence has been proved and results of some sample examples and a small random experiment show that the proposed algorithm is feasible and efficient.

  8. The collection and field chemical analysis of water samples

    International Nuclear Information System (INIS)

    Korte, N.E.; Ealey, D.T.; Hollenbach, M.H.

    1984-01-01

    A successful water sampling program requires a clear understanding of appropriate measurement and sampling procedures in order to obtain reliable field data and representative samples. It is imperative that the personnel involved have a thorough knowledge of the limitations of the techniques being used. Though this seems self-evident, many sampling and field-chemical-analysis programs are still not properly conducted. Recognizing these problems, the Department of Energy contracted with Bendix Field Engineering Corporation through the Technical Measurements Center to develop and select procedures for water sampling and field chemical analysis at waste sites. The fundamental causese of poor field programs are addressed in this paper, largely through discussion of specific field-measurement techniques and their limitations. Recommendations for improvement, including quality-assurance measures, are also presented

  9. PROBLEM DESCRIPTIONS FOR THE DECISION SUPPORT SOFTWARE DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    SULLIVAN,T.; ARMSTRONG,A.; OSLEEB,J.

    1998-09-14

    This demonstration is focused on evaluating the utility of decision support software in addressing environmental problems. Three endpoints have been selected for evaluation: (1) Visualization, (2) Sample Optimization, and (3) Cost/Benefit Analysis. The definitions for these three areas in this program are listed.

  10. A metric for cross-sample comparisons using logit and probit

    DEFF Research Database (Denmark)

    Karlson, Kristian Bernt

    relative to an arbitrary scale, which makes the coefficients difficult both to interpret and to compare across groups or samples. Do differences in coefficients reflect true differences or differences in scales? This cross-sample comparison problem raises concerns for comparative research. However, we......* across groups or samples, making it suitable for situations met in real applications in comparative research. Our derivations also extend to the probit and to ordered and multinomial models. The new metric is implemented in the Stata command nlcorr....

  11. Pre-Service and In-Service Teachers' Metacognitive Knowledge about Problem-Solving Strategies

    Science.gov (United States)

    Metallidou, Panayiota

    2009-01-01

    The present study based on Antonietti, A., Ignazi, S., & Perego, P. (2000). Metacognitive knowledge about problem-solving methods. "British Journal of Educational Psychology, 70", 1-16 methodology with the aim to examine primary school teachers' metacognitive knowledge about problem-solving strategies. A sample of 338 in-service (172) and…

  12. Developing non-routine problems for assessing students’ mathematical literacy

    Science.gov (United States)

    Murdiyani, N. M.

    2018-03-01

    The purpose of this study is to develop non-routine problems for assessing the mathematics literacy skills of students, which is valid, practical, and effective. It is based on the previous research said that Indonesian students’ mathematical literacy is still low. The results of this study can be used as a guide in developing the evaluation questions that can train students to improve the ability of solving non-routine problems in everyday life. This research type is formative evaluation that consists of preliminary, self evaluation, expert reviews, one-to-one, small group, and field test. The sample of this research is grade 8 students at one of Junior High School in Yogyakarta. This study results in mathematics literacy problems prototype consisting of level 1 to level 6 problems similar to PISA problems. This study also discusses the examples of students’ answer and their reasoning.

  13. Effectiveness of discovery learning model on mathematical problem solving

    Science.gov (United States)

    Herdiana, Yunita; Wahyudin, Sispiyati, Ririn

    2017-08-01

    This research is aimed to describe the effectiveness of discovery learning model on mathematical problem solving. This research investigate the students' problem solving competency before and after learned by using discovery learning model. The population used in this research was student in grade VII in one of junior high school in West Bandung Regency. From nine classes, class VII B were randomly selected as the sample of experiment class, and class VII C as control class, which consist of 35 students every class. The method in this research was quasi experiment. The instrument in this research is pre-test, worksheet and post-test about problem solving of mathematics. Based on the research, it can be conclude that the qualification of problem solving competency of students who gets discovery learning model on level 80%, including in medium category and it show that discovery learning model effective to improve mathematical problem solving.

  14. Ear recognition from one sample per person.

    Directory of Open Access Journals (Sweden)

    Long Chen

    Full Text Available Biometrics has the advantages of efficiency and convenience in identity authentication. As one of the most promising biometric-based methods, ear recognition has received broad attention and research. Previous studies have achieved remarkable performance with multiple samples per person (MSPP in the gallery. However, most conventional methods are insufficient when there is only one sample per person (OSPP available in the gallery. To solve the OSPP problem by maximizing the use of a single sample, this paper proposes a hybrid multi-keypoint descriptor sparse representation-based classification (MKD-SRC ear recognition approach based on 2D and 3D information. Because most 3D sensors capture 3D data accessorizing the corresponding 2D data, it is sensible to use both types of information. First, the ear region is extracted from the profile. Second, keypoints are detected and described for both the 2D texture image and 3D range image. Then, the hybrid MKD-SRC algorithm is used to complete the recognition with only OSPP in the gallery. Experimental results on a benchmark dataset have demonstrated the feasibility and effectiveness of the proposed method in resolving the OSPP problem. A Rank-one recognition rate of 96.4% is achieved for a gallery of 415 subjects, and the time involved in the computation is satisfactory compared to conventional methods.

  15. Ear recognition from one sample per person.

    Science.gov (United States)

    Chen, Long; Mu, Zhichun; Zhang, Baoqing; Zhang, Yi

    2015-01-01

    Biometrics has the advantages of efficiency and convenience in identity authentication. As one of the most promising biometric-based methods, ear recognition has received broad attention and research. Previous studies have achieved remarkable performance with multiple samples per person (MSPP) in the gallery. However, most conventional methods are insufficient when there is only one sample per person (OSPP) available in the gallery. To solve the OSPP problem by maximizing the use of a single sample, this paper proposes a hybrid multi-keypoint descriptor sparse representation-based classification (MKD-SRC) ear recognition approach based on 2D and 3D information. Because most 3D sensors capture 3D data accessorizing the corresponding 2D data, it is sensible to use both types of information. First, the ear region is extracted from the profile. Second, keypoints are detected and described for both the 2D texture image and 3D range image. Then, the hybrid MKD-SRC algorithm is used to complete the recognition with only OSPP in the gallery. Experimental results on a benchmark dataset have demonstrated the feasibility and effectiveness of the proposed method in resolving the OSPP problem. A Rank-one recognition rate of 96.4% is achieved for a gallery of 415 subjects, and the time involved in the computation is satisfactory compared to conventional methods.

  16. A Frequency Matching Method: Solving Inverse Problems by Use of Geologically Realistic Prior Information

    DEFF Research Database (Denmark)

    Lange, Katrine; Frydendall, Jan; Cordua, Knud Skou

    2012-01-01

    The frequency matching method defines a closed form expression for a complex prior that quantifies the higher order statistics of a proposed solution model to an inverse problem. While existing solution methods to inverse problems are capable of sampling the solution space while taking into account...... arbitrarily complex a priori information defined by sample algorithms, it is not possible to directly compute the maximum a posteriori model, as the prior probability of a solution model cannot be expressed. We demonstrate how the frequency matching method enables us to compute the maximum a posteriori...... solution model to an inverse problem by using a priori information based on multiple point statistics learned from training images. We demonstrate the applicability of the suggested method on a synthetic tomographic crosshole inverse problem....

  17. Generalized coherent states for the Coulomb problem in one dimension

    International Nuclear Information System (INIS)

    Nouri, S.

    2002-01-01

    A set of generalized coherent states for the one-dimensional Coulomb problem in coordinate representation is constructed. At first, we obtain a mapping for proper transformation of the one-dimensional Coulomb problem into a nonrotating four-dimensional isotropic harmonic oscillator in the hyperspherical space, and the generalized coherent states for the one-dimensional Coulomb problem is then obtained in exact closed form. This exactly soluble model can provide an adequate means for a quantum coherency description of the Coulomb problem in one dimension, sample for coherent aspects of the exciton model in one-dimension example in high-temperature superconductivity, semiconductors, and polymers. Also, it can be useful for investigating the coherent scattering of the Coulomb particles in one dimension

  18. Social problem solving ability predicts mental health among undergraduate students

    Directory of Open Access Journals (Sweden)

    Mansour Ranjbar

    2013-01-01

    Methods : In this correlational- descriptive study, 369 (208 female and 161 male from, Mazandaran University of Medical Science were selected through stratified random sampling method. In order to collect the data, the social problem solving inventory-revised and general health questionnaire were used. Data were analyzed through SPSS-19, Pearson′s correlation, t test, and stepwise regression analysis. Results : Data analysis showed significant relationship between social problem solving ability and mental health (P < 0.01. Social problem solving ability was significantly associated with the somatic symptoms, anxiety and insomnia, social dysfunction and severe depression (P < 0.01. Conclusions: The results of our study demonstrated that there is a significant correlation between social problem solving ability and mental health.

  19. The Toggle Local Planner for sampling-based motion planning

    KAUST Repository

    Denny, Jory; Amato, Nancy M.

    2012-01-01

    Sampling-based solutions to the motion planning problem, such as the probabilistic roadmap method (PRM), have become commonplace in robotics applications. These solutions are the norm as the dimensionality of the planning space grows, i.e., d > 5

  20. Sign problem and Monte Carlo calculations beyond Lefschetz thimbles

    International Nuclear Information System (INIS)

    Alexandru, Andrei; Başar, Gökçe; Bedaque, Paulo F.; Ridgway, Gregory W.; Warrington, Neill C.

    2016-01-01

    We point out that Monte Carlo simulations of theories with severe sign problems can be profitably performed over manifolds in complex space different from the one with fixed imaginary part of the action (“Lefschetz thimble”). We describe a family of such manifolds that interpolate between the tangent space at one critical point (where the sign problem is milder compared to the real plane but in some cases still severe) and the union of relevant thimbles (where the sign problem is mild but a multimodal distribution function complicates the Monte Carlo sampling). We exemplify this approach using a simple 0+1 dimensional fermion model previously used on sign problem studies and show that it can solve the model for some parameter values where a solution using Lefschetz thimbles was elusive.

  1. Attention problems in childhood and adult substance use.

    Science.gov (United States)

    Galéra, Cédric; Pingault, Jean-Baptiste; Fombonne, Eric; Michel, Grégory; Lagarde, Emmanuel; Bouvard, Manuel-Pierre; Melchior, Maria

    2013-12-01

    To assess the link between childhood attention problems (AP) and substance use 18 years later. This cohort study was conducted in a community sample of 1103 French youths followed from 1991 to 2009. Exposures and covariates were childhood behavioral problems (based on parental report at baseline), early substance use, school difficulties, and family adversity. Outcome measures were regular tobacco smoking, alcohol problems, problematic cannabis use, and lifetime cocaine use (based on youth reports at follow-up). Individuals with high levels of childhood AP had higher rates of substance use (regular tobacco smoking, alcohol problems, problematic cannabis use, and lifetime cocaine use). However, when taking into account other childhood behavioral problems, early substance use, school difficulties, and family adversity, childhood AP were related only to regular tobacco smoking and lifetime cocaine use. Early cannabis exposure was the strongest risk factor for all substance use problems. This longitudinal community-based study shows that, except for tobacco and cocaine, the association between childhood AP and substance use is confounded by a range of early risk factors. Early cannabis exposure plays a central role in later substance use. Copyright © 2013 Mosby, Inc. All rights reserved.

  2. Monte Carlo method in radiation transport problems

    International Nuclear Information System (INIS)

    Dejonghe, G.; Nimal, J.C.; Vergnaud, T.

    1986-11-01

    In neutral radiation transport problems (neutrons, photons), two values are important: the flux in the phase space and the density of particles. To solve the problem with Monte Carlo method leads to, among other things, build a statistical process (called the play) and to provide a numerical value to a variable x (this attribution is called score). Sampling techniques are presented. Play biasing necessity is proved. A biased simulation is made. At last, the current developments (rewriting of programs for instance) are presented due to several reasons: two of them are the vectorial calculation apparition and the photon and neutron transport in vacancy media [fr

  3. Greenhouse problem in the Amazon jungle clearing

    International Nuclear Information System (INIS)

    Reis, E.J.; Margulis, S.

    1991-01-01

    This paper discusses the contribution of Amazon jungle clearing to the greenhouse problem and makes an assessment of long-run prospects. The introductory sections pose the problem from both international and Brazilian perspectives. The next section describes major features of the Amazonia ecosystems and presents methods and evidence on deforestation and on its impact on carbon dioxide emissions. Based upon cross-section information for a sample of municipalities in the Brazilian Amazon, the following section estimates elasticities of deforestation in relation to major economic factors- government policies included- and uses them to make projections for the future pace of deforestation. The last section discusses policy alternatives to slow down forest conversion

  4. PISA 2012 Analysis of School Variables Affecting Problem-Solving Competency: Turkey-Serbia Comparison

    Directory of Open Access Journals (Sweden)

    Emine YAVUZ

    2017-12-01

    Full Text Available According to the OECD's PISA 2012 Turkey problem-solving report, Turkey and Serbia are at the same mathematical literacy level. However, Serbia's average of problem-solving competency is said to be higher than Turkey's. In this study, school variables that affect problem-solving competency of the two countries were examined and compared. The method of the study was causal comparison method, and HLM analysis was performed on data of 4494 students from 147 schools in Turkey sample and 4059 students from 132 schools in Serbia sample separately. As a result of HLM analysis, "obstacle and family donation" variable for Serbia and "abandon, teacher morale and mathematics competition" variable for Turkey were statistically significant. Although it was found that for each countries different variables influence the problem-solving competency, it was quite remarkable that these variables are in common in that they are components of the school climate concept.

  5. Metacognition Process of Students with High Mathematics Anxiety in Mathematics Problem-Solving

    OpenAIRE

    Patrisius Afrisno Udil; Tri Atmojo Kusmayadi; Riyadi Riyadi

    2017-01-01

    This study aims to find out students’ metacognition process while solving the mathematics problem. It focuses on analyzing the metacognition process of students with high mathematics anxiety based on Polya’s problem solving phases. This study uses qualitative research with case study strategy. The subjects consist of 8 students of 7th grade selected through purposive sampling. Data in the form of Mathematics Anxiety Scale (MAS) result and recorded interview while solving mathematics problems ...

  6. NAIL SAMPLING TECHNIQUE AND ITS INTERPRETATION

    OpenAIRE

    TZAR MN; LEELAVATHI M

    2011-01-01

    The clinical suspicion of onychomyosis based on appearance of the nails, requires culture for confirmation. This is because treatment requires prolonged use of systemic agents which may cause side effects. One of the common problems encountered is improper nail sampling technique which results in loss of essential information. The unfamiliar terminologies used in reporting culture results may intimidate physicians resulting in misinterpretation and hamper treatment decision. This article prov...

  7. Connecting Research to Teaching: Using Data to Motivate the Use of Empirical Sampling Distributions

    Science.gov (United States)

    Lee, Hollylynne S.; Starling, Tina T.; Gonzalez, Marggie D.

    2014-01-01

    Research shows that students often struggle with understanding empirical sampling distributions. Using hands-on and technology models and simulations of problems generated by real data help students begin to make connections between repeated sampling, sample size, distribution, variation, and center. A task to assist teachers in implementing…

  8. Robustness to non-normality of common tests for the many-sample location problem

    Directory of Open Access Journals (Sweden)

    Azmeri Khan

    2003-01-01

    Full Text Available This paper studies the effect of deviating from the normal distribution assumption when considering the power of two many-sample location test procedures: ANOVA (parametric and Kruskal-Wallis (non-parametric. Power functions for these tests under various conditions are produced using simulation, where the simulated data are produced using MacGillivray and Cannon's [10] recently suggested g-and-k distribution. This distribution can provide data with selected amounts of skewness and kurtosis by varying two nearly independent parameters.

  9. Sampling of temporal networks: Methods and biases

    Science.gov (United States)

    Rocha, Luis E. C.; Masuda, Naoki; Holme, Petter

    2017-11-01

    Temporal networks have been increasingly used to model a diversity of systems that evolve in time; for example, human contact structures over which dynamic processes such as epidemics take place. A fundamental aspect of real-life networks is that they are sampled within temporal and spatial frames. Furthermore, one might wish to subsample networks to reduce their size for better visualization or to perform computationally intensive simulations. The sampling method may affect the network structure and thus caution is necessary to generalize results based on samples. In this paper, we study four sampling strategies applied to a variety of real-life temporal networks. We quantify the biases generated by each sampling strategy on a number of relevant statistics such as link activity, temporal paths and epidemic spread. We find that some biases are common in a variety of networks and statistics, but one strategy, uniform sampling of nodes, shows improved performance in most scenarios. Given the particularities of temporal network data and the variety of network structures, we recommend that the choice of sampling methods be problem oriented to minimize the potential biases for the specific research questions on hand. Our results help researchers to better design network data collection protocols and to understand the limitations of sampled temporal network data.

  10. A thermostat for precise measurements of thermoresistance of small samples

    International Nuclear Information System (INIS)

    Rusinowski, Z.; Slowinski, B.; Winiewski, R.

    1996-01-01

    In the work a simple experimental set-up is described in which special attention is paid to the important problem of the thermal stability of thermoresistance measurements of small samples of manganin

  11. Response rates and selection problems, with emphasis on mental health variables and DNA sampling, in large population-based, cross-sectional and longitudinal studies of adolescents in Norway.

    Science.gov (United States)

    Bjertness, Espen; Sagatun, Ase; Green, Kristian; Lien, Lars; Søgaard, Anne Johanne; Selmer, Randi

    2010-10-12

    Selection bias is a threat to the internal validity of epidemiological studies. In light of a growing number of studies which aim to provide DNA, as well as a considerable number of invitees who declined to participate, we discuss response rates, predictors of lost to follow-up and failure to provide DNA, and the presence of possible selection bias, based on five samples of adolescents. We included nearly 7,000 adolescents from two longitudinal studies of 18/19 year olds with two corresponding cross-sectional baseline studies at age 15/16 (10th graders), and one cross-sectional study of 13th graders (18/19 years old). DNA was sampled from the cheek mucosa of 18/19 year olds. Predictors of lost to follow-up and failure to provide DNA were studied by Poisson regression. Selection bias in the follow-up at age 18/19 was estimated through investigation of prevalence ratios (PRs) between selected exposures (physical activity, smoking) and outcome variables (general health, mental distress, externalizing problems) measured at baseline. Out of 5,750 who participated at age 15/16, we lost 42% at follow-up at age 18/19. The percentage of participants who gave their consent to DNA provision was as high as the percentage that consented to a linkage of data with other health registers and surveys, approximately 90%. Significant predictors of lost to follow-up and failure to provide DNA samples in the present genetic epidemiological study were: male gender; non-western ethnicity; postal survey compared with school-based; low educational plans; low education and income of father; low perceived family economy; unmarried parents; poor self-reported health; externalized symptoms and smoking, with some differences in subgroups of ethnicity and gender. The association measures (PRs) were quite similar among participants and all invitees, with some minor discrepancies in subgroups of non-western boys and girls. Lost to follow-up had marginal impact on the estimated prevalence ratios

  12. The Meaning of Emotional Overinvolvement in Early Development: Prospective Relations with Child Behavior Problems

    Science.gov (United States)

    Khafi, Tamar Y.; Yates, Tuppett M.; Sher-Censor, Efrat

    2015-01-01

    Emotional Overinvolvement (EOI) in parents’ Five Minute Speech Samples (FMSS; Magaña-Amato, 1993) is thought to measure overconcern and enmeshment with one’s child. Although related to maladaptive outcomes in studies of adult children, FMSS-EOI evidences varied relations with behavior problems in studies with young children. These mixed findings may indicate that certain FMSS-EOI criteria reflect inappropriate and excessive involvement with adult children, but do not indicate maladaptive processes when parenting younger children. Thus, this study evaluated relations of each FMSS-EOI criterion with changes in child behavior problems from preschool to first grade in a community sample of 223 child-mother dyads (47.98% female; Mage_W1 = 49.08 months; 56.50% Hispanic/Latina). Maternal FMSS-EOI ratings were obtained at wave 1, and independent examiners rated child externalizing and internalizing behavior problems at wave 1 and two years later. Path analyses indicated that both the Self-Sacrifice/Overprotection (SSOP) and Statements of Attitude (SOAs) FMSS-EOI criteria predicted increased externalizing problems. In contrast, Excessive Detail and Exaggerated Praise were not related to child externalizing behavior problems, and Emotional Display was not evident in this sample. None of the FMSS-EOI criteria evidenced significant relations with internalizing behavior problems. Multigroup comparisons indicated that the effect of SOAs on externalizing behavior problems was significant for boys but not for girls, and there were no significant group differences by race/ethnicity. These findings point to the salience of SSOP and SOAs for understanding the developmental significance of EOI in early development. PMID:26147935

  13. From inverse problems to learning: a Statistical Mechanics approach

    Science.gov (United States)

    Baldassi, Carlo; Gerace, Federica; Saglietti, Luca; Zecchina, Riccardo

    2018-01-01

    We present a brief introduction to the statistical mechanics approaches for the study of inverse problems in data science. We then provide concrete new results on inferring couplings from sampled configurations in systems characterized by an extensive number of stable attractors in the low temperature regime. We also show how these result are connected to the problem of learning with realistic weak signals in computational neuroscience. Our techniques and algorithms rely on advanced mean-field methods developed in the context of disordered systems.

  14. Post-treatment problems of African American breast cancer survivors.

    Science.gov (United States)

    Barsevick, Andrea M; Leader, Amy; Bradley, Patricia K; Avery, Tiffany; Dean, Lorraine T; DiCarlo, Melissa; Hegarty, Sarah E

    2016-12-01

    African American breast cancer survivors (AABCS) have a lower survival rate across all disease stages (79 %) compared with White survivors (92 %) and often have more aggressive forms of breast cancer requiring multimodality treatment, so they could experience a larger burden of post-treatment quality of life (QOL) problems. This paper reports a comprehensive assessment of the number, severity, and domains of problems faced by AABCS within 5 years after treatment completion and identifies subgroups at risk for these problems. A population-based random sample was obtained from the Pennsylvania Cancer Registry of African American females over 18 years of age who completed primary treatment for breast cancer in the past 5 years. A mailed survey was used to document survivorship problems. Two hundred ninety-seven AABCS completed the survey. The median number of survivor problems reported was 15. Exploratory factor analysis of the problem scale revealed four domains: emotional problems, physical problems, lack of resources, and sexuality problems. Across problem domains, younger age, more comorbid conditions, and greater medical mistrust were risk factors for more severe problems. The results demonstrated that AABCS experienced significant problem burden in the early years after diagnosis and treatment. In addition to emotional and physical problem domains that were documented in previous research, two problem domains unique to AABCS included lack of resources and sexuality concerns. At risk groups should be targeted for intervention. The study results reported in this manuscript will inform future research to address problems of AABCS as they make the transition from cancer patient to cancer survivor.

  15. Maltreatment, the Oxytocin Receptor Gene, and Conduct Problems Among Male and Female Teenagers

    Directory of Open Access Journals (Sweden)

    Dimitrios Andreou

    2018-03-01

    Full Text Available The oxytocin receptor gene (OXTR influences human behavior. The G allele of OXTR rs53576 has been associated with both prosocial and maladaptive behaviors but few studies have taken account of environmental factors. The present study determined whether the association of childhood maltreatment with conduct problems was modified by OXTR rs53576 genotypes. In a general population sample of 1591 teenagers, conduct problems as well as maltreatment were measured by self-report. DNA was extracted from saliva samples. In males, there was a significant positive association between maltreatment and conduct problems independent of the genotype. In females, among G allele carriers, the level of conduct problems was significantly higher among those who had been maltreated as compared to those not maltreated. By contrast, among female AA carriers, conduct problems did not vary between those who were, and who were not, maltreated. The results indicate that OXTR rs53576 plays a role in antisocial behavior in females such that the G allele confers vulnerability for antisocial behavior if they experience maltreatment, whereas the A allele has a protective effect.

  16. Problem-solving deficits in Iranian people with borderline personality disorder.

    Science.gov (United States)

    Akbari Dehaghi, Ashraf; Kaviani, Hossein; Tamanaeefar, Shima

    2014-01-01

    Interventions for people suffering from borderline personality disorder (BPD), such as dialectical behavior therapy, often include a problem-solving component. However, there is an absence of published studies examining the problem-solving abilities of this client group in Iran. The study compared inpatients and outpatients with BPD and a control group on problem-solving capabilities in an Iranian sample. It was hypothesized that patients with BPD would have more deficiencies in this area. Fifteen patients with BPD were compared to 15 healthy participants. Means-ends problem-solving task (MEPS) was used to measure problem-solving skills in both groups. BPD group reported less effective strategies in solving problems as opposed to the healthy group. Compared to the control group, participants with BPD provided empirical support for the use of problem-solving interventions with people suffering from BPD. The findings supported the idea that a problem-solving intervention can be efficiently applied either as a stand-alone therapy or in conjunction with other available psychotherapies to treat people with BPD.

  17. Decomposition and (importance) sampling techniques for multi-stage stochastic linear programs

    Energy Technology Data Exchange (ETDEWEB)

    Infanger, G.

    1993-11-01

    The difficulty of solving large-scale multi-stage stochastic linear programs arises from the sheer number of scenarios associated with numerous stochastic parameters. The number of scenarios grows exponentially with the number of stages and problems get easily out of hand even for very moderate numbers of stochastic parameters per stage. Our method combines dual (Benders) decomposition with Monte Carlo sampling techniques. We employ importance sampling to efficiently obtain accurate estimates of both expected future costs and gradients and right-hand sides of cuts. The method enables us to solve practical large-scale problems with many stages and numerous stochastic parameters per stage. We discuss the theory of sharing and adjusting cuts between different scenarios in a stage. We derive probabilistic lower and upper bounds, where we use importance path sampling for the upper bound estimation. Initial numerical results turned out to be promising.

  18. Sampling/classification of gasifier particulates

    International Nuclear Information System (INIS)

    Wegrzyn, J.

    1984-01-01

    A high temperature and pressure real time extractive sampling probe for particulate monitoring was built at Brookhaven National Laboratory and tested on Morgantown Energy Technology Center's 42 inch fixed bed gasifier. The probe was specifically designed for the conditions of highly loaded particulate and condensable streams, that exist at the outlet of a fixed bed gasifier. Some of the salient features of the probe are: porous tube gas injection, aerodynamic particle classification in the presence of condensable vapors, β gauge particle detection, and micro processor control. Three of the key design problems were the separation of the particles from the vapor without promoting condensation, the prevention of plugging, and real time monitoring. Some plugging did occur over the seven day sampling period, but by over pressurizing and back purging the clog was blown back into the process stream. The tests validate the proof of concept of the sampling probe and indicated that the particulate output from the bed came in the form of bursts (several minutes in duration) rather than in the form of a steady stream

  19. Little Evidence That Time in Child Care Causes Externalizing Problems During Early Childhood in Norway

    Science.gov (United States)

    Zachrisson, Henrik Daae; Dearing, Eric; Lekhal, Ratib; Toppelberg, Claudio O.

    2012-01-01

    Associations between maternal reports of hours in child care and children’s externalizing problems at 18 and 36 months of age were examined in a population-based Norwegian sample (n = 75,271). Within a sociopolitical context of homogenously high-quality child care, there was little evidence that high quantity of care causes externalizing problems. Using conventional approaches to handling selection bias and listwise deletion for substantial attrition in this sample, more hours in care predicted higher problem levels, yet with small effect sizes. The finding, however, was not robust to using multiple imputation for missing values. Moreover, when sibling and individual fixed-effects models for handling selection bias were used, no relation between hours and problems was evident. PMID:23311645

  20. FAST LABEL: Easy and efficient solution of joint multi-label and estimation problems

    KAUST Repository

    Sundaramoorthi, Ganesh; Hong, Byungwoo

    2014-01-01

    that plague local solutions. Further, in comparison to global methods for the multi-label problem, the method is more efficient and it is easy for a non-specialist to implement. We give sample Matlab code for the multi-label Chan-Vese problem in this paper