Sample records for age-stratified random sample

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

    PubMed

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

    2012-09-01

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

  2. An evaluation of flow-stratified sampling for estimating suspended sediment loads

    Treesearch

    Robert B. Thomas; Jack Lewis

    1995-01-01

    Abstract - Flow-stratified sampling is a new method for sampling water quality constituents such as suspended sediment to estimate loads. As with selection-at-list-time (SALT) and time-stratified sampling, flow-stratified sampling is a statistical method requiring random sampling, and yielding unbiased estimates of load and variance. It can be used to estimate event...

  3. Computerized stratified random site-selection approaches for design of a ground-water-quality sampling network

    USGS Publications Warehouse

    Scott, J.C.

    1990-01-01

    Computer software was written to randomly select sites for a ground-water-quality sampling network. The software uses digital cartographic techniques and subroutines from a proprietary geographic information system. The report presents the approaches, computer software, and sample applications. It is often desirable to collect ground-water-quality samples from various areas in a study region that have different values of a spatial characteristic, such as land-use or hydrogeologic setting. A stratified network can be used for testing hypotheses about relations between spatial characteristics and water quality, or for calculating statistical descriptions of water-quality data that account for variations that correspond to the spatial characteristic. In the software described, a study region is subdivided into areal subsets that have a common spatial characteristic to stratify the population into several categories from which sampling sites are selected. Different numbers of sites may be selected from each category of areal subsets. A population of potential sampling sites may be defined by either specifying a fixed population of existing sites, or by preparing an equally spaced population of potential sites. In either case, each site is identified with a single category, depending on the value of the spatial characteristic of the areal subset in which the site is located. Sites are selected from one category at a time. One of two approaches may be used to select sites. Sites may be selected randomly, or the areal subsets in the category can be grouped into cells and sites selected randomly from each cell.

  4. Estimation of population mean in the presence of measurement error and non response under stratified random sampling

    PubMed Central

    Shabbir, Javid

    2018-01-01

    In the present paper we propose an improved class of estimators in the presence of measurement error and non-response under stratified random sampling for estimating the finite population mean. The theoretical and numerical studies reveal that the proposed class of estimators performs better than other existing estimators. PMID:29401519

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

    Treesearch

    Jack Lewis

    2003-01-01

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

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

    Treesearch

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

    2012-01-01

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

  7. Effects of unstratified and centre-stratified randomization in multi-centre clinical trials.

    PubMed

    Anisimov, Vladimir V

    2011-01-01

    This paper deals with the analysis of randomization effects in multi-centre clinical trials. The two randomization schemes most often used in clinical trials are considered: unstratified and centre-stratified block-permuted randomization. The prediction of the number of patients randomized to different treatment arms in different regions during the recruitment period accounting for the stochastic nature of the recruitment and effects of multiple centres is investigated. A new analytic approach using a Poisson-gamma patient recruitment model (patients arrive at different centres according to Poisson processes with rates sampled from a gamma distributed population) and its further extensions is proposed. Closed-form expressions for corresponding distributions of the predicted number of the patients randomized in different regions are derived. In the case of two treatments, the properties of the total imbalance in the number of patients on treatment arms caused by using centre-stratified randomization are investigated and for a large number of centres a normal approximation of imbalance is proved. The impact of imbalance on the power of the study is considered. It is shown that the loss of statistical power is practically negligible and can be compensated by a minor increase in sample size. The influence of patient dropout is also investigated. The impact of randomization on predicted drug supply overage is discussed. Copyright © 2010 John Wiley & Sons, Ltd.

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

    ERIC Educational Resources Information Center

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

    2014-01-01

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

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

    Treesearch

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

    2014-01-01

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

  10. Data splitting for artificial neural networks using SOM-based stratified sampling.

    PubMed

    May, R J; Maier, H R; Dandy, G C

    2010-03-01

    Data splitting is an important consideration during artificial neural network (ANN) development where hold-out cross-validation is commonly employed to ensure generalization. Even for a moderate sample size, the sampling methodology used for data splitting can have a significant effect on the quality of the subsets used for training, testing and validating an ANN. Poor data splitting can result in inaccurate and highly variable model performance; however, the choice of sampling methodology is rarely given due consideration by ANN modellers. Increased confidence in the sampling is of paramount importance, since the hold-out sampling is generally performed only once during ANN development. This paper considers the variability in the quality of subsets that are obtained using different data splitting approaches. A novel approach to stratified sampling, based on Neyman sampling of the self-organizing map (SOM), is developed, with several guidelines identified for setting the SOM size and sample allocation in order to minimize the bias and variance in the datasets. Using an example ANN function approximation task, the SOM-based approach is evaluated in comparison to random sampling, DUPLEX, systematic stratified sampling, and trial-and-error sampling to minimize the statistical differences between data sets. Of these approaches, DUPLEX is found to provide benchmark performance with good model performance, with no variability. The results show that the SOM-based approach also reliably generates high-quality samples and can therefore be used with greater confidence than other approaches, especially in the case of non-uniform datasets, with the benefit of scalability to perform data splitting on large datasets. Copyright 2009 Elsevier Ltd. All rights reserved.

  11. [Study of spatial stratified sampling strategy of Oncomelania hupensis snail survey based on plant abundance].

    PubMed

    Xun-Ping, W; An, Z

    2017-07-27

    Objective To optimize and simplify the survey method of Oncomelania hupensis snails in marshland endemic regions of schistosomiasis, so as to improve the precision, efficiency and economy of the snail survey. Methods A snail sampling strategy (Spatial Sampling Scenario of Oncomelania based on Plant Abundance, SOPA) which took the plant abundance as auxiliary variable was explored and an experimental study in a 50 m×50 m plot in a marshland in the Poyang Lake region was performed. Firstly, the push broom surveyed data was stratified into 5 layers by the plant abundance data; then, the required numbers of optimal sampling points of each layer through Hammond McCullagh equation were calculated; thirdly, every sample point in the line with the Multiple Directional Interpolation (MDI) placement scheme was pinpointed; and finally, the comparison study among the outcomes of the spatial random sampling strategy, the traditional systematic sampling method, the spatial stratified sampling method, Sandwich spatial sampling and inference and SOPA was performed. Results The method (SOPA) proposed in this study had the minimal absolute error of 0.213 8; and the traditional systematic sampling method had the largest estimate, and the absolute error was 0.924 4. Conclusion The snail sampling strategy (SOPA) proposed in this study obtains the higher estimation accuracy than the other four methods.

  12. Stratified exact tests for the weak causal null hypothesis in randomized trials with a binary outcome.

    PubMed

    Chiba, Yasutaka

    2017-09-01

    Fisher's exact test is commonly used to compare two groups when the outcome is binary in randomized trials. In the context of causal inference, this test explores the sharp causal null hypothesis (i.e. the causal effect of treatment is the same for all subjects), but not the weak causal null hypothesis (i.e. the causal risks are the same in the two groups). Therefore, in general, rejection of the null hypothesis by Fisher's exact test does not mean that the causal risk difference is not zero. Recently, Chiba (Journal of Biometrics and Biostatistics 2015; 6: 244) developed a new exact test for the weak causal null hypothesis when the outcome is binary in randomized trials; the new test is not based on any large sample theory and does not require any assumption. In this paper, we extend the new test; we create a version of the test applicable to a stratified analysis. The stratified exact test that we propose is general in nature and can be used in several approaches toward the estimation of treatment effects after adjusting for stratification factors. The stratified Fisher's exact test of Jung (Biometrical Journal 2014; 56: 129-140) tests the sharp causal null hypothesis. This test applies a crude estimator of the treatment effect and can be regarded as a special case of our proposed exact test. Our proposed stratified exact test can be straightforwardly extended to analysis of noninferiority trials and to construct the associated confidence interval. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Number of pins in two-stage stratified sampling for estimating herbage yield

    Treesearch

    William G. O' Regan; C. Eugene Conrad

    1975-01-01

    In a two-stage stratified procedure for sampling herbage yield, plots are stratified by a pin frame in stage one, and clipped. In stage two, clippings from selected plots are sorted, dried, and weighed. Sample size and distribution of plots between the two stages are determined by equations. A way to compute the effect of number of pins on the variance of estimated...

  14. Assessment of the effect of population and diary sampling methods on estimation of school-age children exposure to fine particles.

    PubMed

    Che, W W; Frey, H Christopher; Lau, Alexis K H

    2014-12-01

    Population and diary sampling methods are employed in exposure models to sample simulated individuals and their daily activity on each simulation day. Different sampling methods may lead to variations in estimated human exposure. In this study, two population sampling methods (stratified-random and random-random) and three diary sampling methods (random resampling, diversity and autocorrelation, and Markov-chain cluster [MCC]) are evaluated. Their impacts on estimated children's exposure to ambient fine particulate matter (PM2.5 ) are quantified via case studies for children in Wake County, NC for July 2002. The estimated mean daily average exposure is 12.9 μg/m(3) for simulated children using the stratified population sampling method, and 12.2 μg/m(3) using the random sampling method. These minor differences are caused by the random sampling among ages within census tracts. Among the three diary sampling methods, there are differences in the estimated number of individuals with multiple days of exposures exceeding a benchmark of concern of 25 μg/m(3) due to differences in how multiday longitudinal diaries are estimated. The MCC method is relatively more conservative. In case studies evaluated here, the MCC method led to 10% higher estimation of the number of individuals with repeated exposures exceeding the benchmark. The comparisons help to identify and contrast the capabilities of each method and to offer insight regarding implications of method choice. Exposure simulation results are robust to the two population sampling methods evaluated, and are sensitive to the choice of method for simulating longitudinal diaries, particularly when analyzing results for specific microenvironments or for exposures exceeding a benchmark of concern. © 2014 Society for Risk Analysis.

  15. A New Stratified Sampling Procedure which Decreases Error Estimation of Varroa Mite Number on Sticky Boards.

    PubMed

    Kretzschmar, A; Durand, E; Maisonnasse, A; Vallon, J; Le Conte, Y

    2015-06-01

    A new procedure of stratified sampling is proposed in order to establish an accurate estimation of Varroa destructor populations on sticky bottom boards of the hive. It is based on the spatial sampling theory that recommends using regular grid stratification in the case of spatially structured process. The distribution of varroa mites on sticky board being observed as spatially structured, we designed a sampling scheme based on a regular grid with circles centered on each grid element. This new procedure is then compared with a former method using partially random sampling. Relative error improvements are exposed on the basis of a large sample of simulated sticky boards (n=20,000) which provides a complete range of spatial structures, from a random structure to a highly frame driven structure. The improvement of varroa mite number estimation is then measured by the percentage of counts with an error greater than a given level. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Stratified Sampling Design Based on Data Mining

    PubMed Central

    Kim, Yeonkook J.; Oh, Yoonhwan; Park, Sunghoon; Cho, Sungzoon

    2013-01-01

    Objectives To explore classification rules based on data mining methodologies which are to be used in defining strata in stratified sampling of healthcare providers with improved sampling efficiency. Methods We performed k-means clustering to group providers with similar characteristics, then, constructed decision trees on cluster labels to generate stratification rules. We assessed the variance explained by the stratification proposed in this study and by conventional stratification to evaluate the performance of the sampling design. We constructed a study database from health insurance claims data and providers' profile data made available to this study by the Health Insurance Review and Assessment Service of South Korea, and population data from Statistics Korea. From our database, we used the data for single specialty clinics or hospitals in two specialties, general surgery and ophthalmology, for the year 2011 in this study. Results Data mining resulted in five strata in general surgery with two stratification variables, the number of inpatients per specialist and population density of provider location, and five strata in ophthalmology with two stratification variables, the number of inpatients per specialist and number of beds. The percentages of variance in annual changes in the productivity of specialists explained by the stratification in general surgery and ophthalmology were 22% and 8%, respectively, whereas conventional stratification by the type of provider location and number of beds explained 2% and 0.2% of variance, respectively. Conclusions This study demonstrated that data mining methods can be used in designing efficient stratified sampling with variables readily available to the insurer and government; it offers an alternative to the existing stratification method that is widely used in healthcare provider surveys in South Korea. PMID:24175117

  17. Stratified sampling design based on data mining.

    PubMed

    Kim, Yeonkook J; Oh, Yoonhwan; Park, Sunghoon; Cho, Sungzoon; Park, Hayoung

    2013-09-01

    To explore classification rules based on data mining methodologies which are to be used in defining strata in stratified sampling of healthcare providers with improved sampling efficiency. We performed k-means clustering to group providers with similar characteristics, then, constructed decision trees on cluster labels to generate stratification rules. We assessed the variance explained by the stratification proposed in this study and by conventional stratification to evaluate the performance of the sampling design. We constructed a study database from health insurance claims data and providers' profile data made available to this study by the Health Insurance Review and Assessment Service of South Korea, and population data from Statistics Korea. From our database, we used the data for single specialty clinics or hospitals in two specialties, general surgery and ophthalmology, for the year 2011 in this study. Data mining resulted in five strata in general surgery with two stratification variables, the number of inpatients per specialist and population density of provider location, and five strata in ophthalmology with two stratification variables, the number of inpatients per specialist and number of beds. The percentages of variance in annual changes in the productivity of specialists explained by the stratification in general surgery and ophthalmology were 22% and 8%, respectively, whereas conventional stratification by the type of provider location and number of beds explained 2% and 0.2% of variance, respectively. This study demonstrated that data mining methods can be used in designing efficient stratified sampling with variables readily available to the insurer and government; it offers an alternative to the existing stratification method that is widely used in healthcare provider surveys in South Korea.

  18. Use of simulation to compare the performance of minimization with stratified blocked randomization.

    PubMed

    Toorawa, Robert; Adena, Michael; Donovan, Mark; Jones, Steve; Conlon, John

    2009-01-01

    Minimization is an alternative method to stratified permuted block randomization, which may be more effective at balancing treatments when there are many strata. However, its use in the regulatory setting for industry trials remains controversial, primarily due to the difficulty in interpreting conventional asymptotic statistical tests under restricted methods of treatment allocation. We argue that the use of minimization should be critically evaluated when designing the study for which it is proposed. We demonstrate by example how simulation can be used to investigate whether minimization improves treatment balance compared with stratified randomization, and how much randomness can be incorporated into the minimization before any balance advantage is no longer retained. We also illustrate by example how the performance of the traditional model-based analysis can be assessed, by comparing the nominal test size with the observed test size over a large number of simulations. We recommend that the assignment probability for the minimization be selected using such simulations. Copyright (c) 2008 John Wiley & Sons, Ltd.

  19. Testing homogeneity of proportion ratios for stratified correlated bilateral data in two-arm randomized clinical trials.

    PubMed

    Pei, Yanbo; Tian, Guo-Liang; Tang, Man-Lai

    2014-11-10

    Stratified data analysis is an important research topic in many biomedical studies and clinical trials. In this article, we develop five test statistics for testing the homogeneity of proportion ratios for stratified correlated bilateral binary data based on an equal correlation model assumption. Bootstrap procedures based on these test statistics are also considered. To evaluate the performance of these statistics and procedures, we conduct Monte Carlo simulations to study their empirical sizes and powers under various scenarios. Our results suggest that the procedure based on score statistic performs well generally and is highly recommended. When the sample size is large, procedures based on the commonly used weighted least square estimate and logarithmic transformation with Mantel-Haenszel estimate are recommended as they do not involve any computation of maximum likelihood estimates requiring iterative algorithms. We also derive approximate sample size formulas based on the recommended test procedures. Finally, we apply the proposed methods to analyze a multi-center randomized clinical trial for scleroderma patients. Copyright © 2014 John Wiley & Sons, Ltd.

  20. The study of combining Latin Hypercube Sampling method and LU decomposition method (LULHS method) for constructing spatial random field

    NASA Astrophysics Data System (ADS)

    WANG, P. T.

    2015-12-01

    Groundwater modeling requires to assign hydrogeological properties to every numerical grid. Due to the lack of detailed information and the inherent spatial heterogeneity, geological properties can be treated as random variables. Hydrogeological property is assumed to be a multivariate distribution with spatial correlations. By sampling random numbers from a given statistical distribution and assigning a value to each grid, a random field for modeling can be completed. Therefore, statistics sampling plays an important role in the efficiency of modeling procedure. Latin Hypercube Sampling (LHS) is a stratified random sampling procedure that provides an efficient way to sample variables from their multivariate distributions. This study combines the the stratified random procedure from LHS and the simulation by using LU decomposition to form LULHS. Both conditional and unconditional simulations of LULHS were develpoed. The simulation efficiency and spatial correlation of LULHS are compared to the other three different simulation methods. The results show that for the conditional simulation and unconditional simulation, LULHS method is more efficient in terms of computational effort. Less realizations are required to achieve the required statistical accuracy and spatial correlation.

  1. A direct observation method for auditing large urban centers using stratified sampling, mobile GIS technology and virtual environments.

    PubMed

    Lafontaine, Sean J V; Sawada, M; Kristjansson, Elizabeth

    2017-02-16

    With the expansion and growth of research on neighbourhood characteristics, there is an increased need for direct observational field audits. Herein, we introduce a novel direct observational audit method and systematic social observation instrument (SSOI) for efficiently assessing neighbourhood aesthetics over large urban areas. Our audit method uses spatial random sampling stratified by residential zoning and incorporates both mobile geographic information systems technology and virtual environments. The reliability of our method was tested in two ways: first, in 15 Ottawa neighbourhoods, we compared results at audited locations over two subsequent years, and second; we audited every residential block (167 blocks) in one neighbourhood and compared the distribution of SSOI aesthetics index scores with results from the randomly audited locations. Finally, we present interrater reliability and consistency results on all observed items. The observed neighbourhood average aesthetics index score estimated from four or five stratified random audit locations is sufficient to characterize the average neighbourhood aesthetics. The SSOI was internally consistent and demonstrated good to excellent interrater reliability. At the neighbourhood level, aesthetics is positively related to SES and physical activity and negatively correlated with BMI. The proposed approach to direct neighbourhood auditing performs sufficiently and has the advantage of financial and temporal efficiency when auditing a large city.

  2. Improved Horvitz-Thompson Estimation of Model Parameters from Two-phase Stratified Samples: Applications in Epidemiology

    PubMed Central

    Breslow, Norman E.; Lumley, Thomas; Ballantyne, Christie M; Chambless, Lloyd E.; Kulich, Michal

    2009-01-01

    The case-cohort study involves two-phase sampling: simple random sampling from an infinite super-population at phase one and stratified random sampling from a finite cohort at phase two. Standard analyses of case-cohort data involve solution of inverse probability weighted (IPW) estimating equations, with weights determined by the known phase two sampling fractions. The variance of parameter estimates in (semi)parametric models, including the Cox model, is the sum of two terms: (i) the model based variance of the usual estimates that would be calculated if full data were available for the entire cohort; and (ii) the design based variance from IPW estimation of the unknown cohort total of the efficient influence function (IF) contributions. This second variance component may be reduced by adjusting the sampling weights, either by calibration to known cohort totals of auxiliary variables correlated with the IF contributions or by their estimation using these same auxiliary variables. Both adjustment methods are implemented in the R survey package. We derive the limit laws of coefficients estimated using adjusted weights. The asymptotic results suggest practical methods for construction of auxiliary variables that are evaluated by simulation of case-cohort samples from the National Wilms Tumor Study and by log-linear modeling of case-cohort data from the Atherosclerosis Risk in Communities Study. Although not semiparametric efficient, estimators based on adjusted weights may come close to achieving full efficiency within the class of augmented IPW estimators. PMID:20174455

  3. The revised Temperament and Character Inventory: normative data by sex and age from a Spanish normal randomized sample

    PubMed Central

    Labad, Javier; Martorell, Lourdes; Gaviria, Ana; Bayón, Carmen; Vilella, Elisabet; Cloninger, C. Robert

    2015-01-01

    Objectives. The psychometric properties regarding sex and age for the revised version of the Temperament and Character Inventory (TCI-R) and its derived short version, the Temperament and Character Inventory (TCI-140), were evaluated with a randomized sample from the community. Methods. A randomized sample of 367 normal adult subjects from a Spanish municipality, who were representative of the general population based on sex and age, participated in the current study. Descriptive statistics and internal consistency according to α coefficient were obtained for all of the dimensions and facets. T-tests and univariate analyses of variance, followed by Bonferroni tests, were conducted to compare the distributions of the TCI-R dimension scores by age and sex. Results. On both the TCI-R and TCI-140, women had higher scores for Harm Avoidance, Reward Dependence and Cooperativeness than men, whereas men had higher scores for Persistence. Age correlated negatively with Novelty Seeking, Reward Dependence and Cooperativeness and positively with Harm Avoidance and Self-transcendence. Young subjects between 18 and 35 years had higher scores than older subjects in NS and RD. Subjects between 51 and 77 years scored higher in both HA and ST. The alphas for the dimensions were between 0.74 and 0.87 for the TCI-R and between 0.63 and 0.83 for the TCI-140. Conclusion. Results, which were obtained with a randomized sample, suggest that there are specific distributions of personality traits by sex and age. Overall, both the TCI-R and the abbreviated TCI-140 were reliable in the ‘good-to-excellent’ range. A strength of the current study is the representativeness of the sample. PMID:26713237

  4. Age at first intercourse in an Australian national sample of technical college students.

    PubMed

    Grunseit, A C; Richters, J

    2000-02-01

    This study aims to broaden the current body of knowledge regarding the sexual behaviour of young Australians by examining the age and correlates of age of first intercourse in a national sample of Technical and Further Education apprentices. In 1995, students at randomly selected technical colleges in Australia were surveyed on HIV-related issues. Questionnaires were administered to a stratified cluster sample of automotive, hairdressing and commercial cookery apprentices. Respondents were asked the age at which they first had heterosexual vaginal or anal intercourse. Of 4,055 respondents aged 15-24 years, 3,848 answered the question; 3,195 (83%) had had intercourse. Males and females did not differ significantly. Median age at first intercourse was 16 (range 12-23). In multivariate analysis, older age at first intercourse was associated with: greater age at interview; higher school education; church attendance; and State of residence. The model, however, accounted for only 14% of the variance in age at first intercourse. In this sample, those apprentices who completed secondary school became sexually active later on average than those who left before the end of Year 10. For sex education to occur before sexual initiation, it needs to be offered in primary schools and the first year of high school (aged 11-13 years). Further, as technical college students are likely to initiate sex earlier than their age mates still at school, colleges may be in a position to take responsibility for the continuing sexual education of this group, especially for those students entering college at 15 or 16 years of age.

  5. Stratification of American hearing aid users by age and audiometric characteristics: a method for representative sampling.

    PubMed

    Aronoff, Justin M; Yoon, Yang-soo; Soli, Sigfrid D

    2010-06-01

    Stratified sampling plans can increase the accuracy and facilitate the interpretation of a dataset characterizing a large population. However, such sampling plans have found minimal use in hearing aid (HA) research, in part because of a paucity of quantitative data on the characteristics of HA users. The goal of this study was to devise a quantitatively derived stratified sampling plan for HA research, so that such studies will be more representative and generalizable, and the results obtained using this method are more easily reinterpreted as the population changes. Pure-tone average (PTA) and age information were collected for 84,200 HAs acquired in 2006 and 2007. The distribution of PTA and age was quantified for each HA type and for a composite of all HA users. Based on their respective distributions, PTA and age were each divided into three groups, the combination of which defined the stratification plan. The most populous PTA and age group was also subdivided, allowing greater homogeneity within strata. Finally, the percentage of users in each stratum was calculated. This article provides a stratified sampling plan for HA research, based on a quantitative analysis of the distribution of PTA and age for HA users. Adopting such a sampling plan will make HA research results more representative and generalizable. In addition, data acquired using such plans can be reinterpreted as the HA population changes.

  6. Assessment of fracture risk: value of random population-based samples--the Geelong Osteoporosis Study.

    PubMed

    Henry, M J; Pasco, J A; Seeman, E; Nicholson, G C; Sanders, K M; Kotowicz, M A

    2001-01-01

    Fracture risk is determined by bone mineral density (BMD). The T-score, a measure of fracture risk, is the position of an individual's BMD in relation to a reference range. The aim of this study was to determine the magnitude of change in the T-score when different sampling techniques were used to produce the reference range. Reference ranges were derived from three samples, drawn from the same region: (1) an age-stratified population-based random sample, (2) unselected volunteers, and (3) a selected healthy subset of the population-based sample with no diseases or drugs known to affect bone. T-scores were calculated using the three reference ranges for a cohort of women who had sustained a fracture and as a group had a low mean BMD (ages 35-72 yr; n = 484). For most comparisons, the T-scores for the fracture cohort were more negative using the population reference range. The difference in T-scores reached 1.0 SD. The proportion of the fracture cohort classified as having osteoporosis at the spine was 26, 14, and 23% when the population, volunteer, and healthy reference ranges were applied, respectively. The use of inappropriate reference ranges results in substantial changes to T-scores and may lead to inappropriate management.

  7. Distribution-Preserving Stratified Sampling for Learning Problems.

    PubMed

    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.

  8. A stratified two-stage sampling design for digital soil mapping in a Mediterranean basin

    NASA Astrophysics Data System (ADS)

    Blaschek, Michael; Duttmann, Rainer

    2015-04-01

    The quality of environmental modelling results often depends on reliable soil information. In order to obtain soil data in an efficient manner, several sampling strategies are at hand depending on the level of prior knowledge and the overall objective of the planned survey. This study focuses on the collection of soil samples considering available continuous secondary information in an undulating, 16 km²-sized river catchment near Ussana in southern Sardinia (Italy). A design-based, stratified, two-stage sampling design has been applied aiming at the spatial prediction of soil property values at individual locations. The stratification based on quantiles from density functions of two land-surface parameters - topographic wetness index and potential incoming solar radiation - derived from a digital elevation model. Combined with four main geological units, the applied procedure led to 30 different classes in the given test site. Up to six polygons of each available class were selected randomly excluding those areas smaller than 1ha to avoid incorrect location of the points in the field. Further exclusion rules were applied before polygon selection masking out roads and buildings using a 20m buffer. The selection procedure was repeated ten times and the set of polygons with the best geographical spread were chosen. Finally, exact point locations were selected randomly from inside the chosen polygon features. A second selection based on the same stratification and following the same methodology (selecting one polygon instead of six) was made in order to create an appropriate validation set. Supplementary samples were obtained during a second survey focusing on polygons that have either not been considered during the first phase at all or were not adequately represented with respect to feature size. In total, both field campaigns produced an interpolation set of 156 samples and a validation set of 41 points. The selection of sample point locations has been done using

  9. Gambling problems in the family--a stratified probability sample study of prevalence and reported consequences.

    PubMed

    Wenzel, Hanne Gro; Oren, Anita; Bakken, Inger Johanne

    2008-12-16

    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. 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). 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. Problematic gambling behaviour not only affects the gambling individual but also has a strong impact on the quality of life of family members.

  10. High resolution satellite remote sensing used in a stratified random sampling scheme to quantify the constituent land cover components of the shifting cultivation mosaic of the Democratic Republic of Congo

    NASA Astrophysics Data System (ADS)

    Molinario, G.; Hansen, M.; Potapov, P.

    2016-12-01

    High resolution satellite imagery obtained from the National Geospatial Intelligence Agency through NASA was used to photo-interpret sample areas within the DRC. The area sampled is a stratifcation of the forest cover loss from circa 2014 that either occurred completely within the previosly mapped homogenous area of the Rural Complex, at it's interface with primary forest, or in isolated forest perforations. Previous research resulted in a map of these areas that contextualizes forest loss depending on where it occurs and with what spatial density, leading to a better understading of the real impacts on forest degradation of livelihood shifting cultivation. The stratified random sampling approach of these areas allows the characterization of the constituent land cover types within these areas, and their variability throughout the DRC. Shifting cultivation has a variable forest degradation footprint in the DRC depending on many factors that drive it, but it's role in forest degradation and deforestation had been disputed, leading us to investigate and quantify the clearing and reuse rates within the strata throughout the country.

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

    PubMed Central

    Wenzel, Hanne Gro; Øren, Anita; Bakken, Inger Johanne

    2008-01-01

    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. PMID:19087339

  12. The risk-stratified osteoporosis strategy evaluation study (ROSE): a randomized prospective population-based study. Design and baseline characteristics.

    PubMed

    Rubin, Katrine Hass; Holmberg, Teresa; Rothmann, Mette Juel; Høiberg, Mikkel; Barkmann, Reinhard; Gram, Jeppe; Hermann, Anne Pernille; Bech, Mickael; Rasmussen, Ole; Glüer, Claus C; Brixen, Kim

    2015-02-01

    The risk-stratified osteoporosis strategy evaluation study (ROSE) is a randomized prospective population-based study investigating the effectiveness of a two-step screening program for osteoporosis in women. This paper reports the study design and baseline characteristics of the study population. 35,000 women aged 65-80 years were selected at random from the population in the Region of Southern Denmark and-before inclusion-randomized to either a screening group or a control group. As first step, a self-administered questionnaire regarding risk factors for osteoporosis based on FRAX(®) was issued to both groups. As second step, subjects in the screening group with a 10-year probability of major osteoporotic fractures ≥15% were offered a DXA scan. Patients diagnosed with osteoporosis from the DXA scan were advised to see their GP and discuss pharmaceutical treatment according to Danish National guidelines. The primary outcome is incident clinical fractures as evaluated through annual follow-up using the Danish National Patient Registry. The secondary outcomes are cost-effectiveness, participation rate, and patient preferences. 20,904 (60%) women participated and included in the baseline analyses (10,411 in screening and 10,949 in control group). The mean age was 71 years. As expected by randomization, the screening and control groups had similar baseline characteristics. Screening for osteoporosis is at present not evidence based according to the WHO screening criteria. The ROSE study is expected to provide knowledge of the effectiveness of a screening strategy that may be implemented in health care systems to prevent fractures.

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

    PubMed

    Rugulies, Reiner; Madsen, Ida E H; Nielsen, Maj Britt D; Olsen, Lis R; Mortensen, Erik L; Bech, Per

    2010-08-01

    To analyze the distribution of depressive, anxiety, and somatization symptoms across different occupational positions in a random sample of Danish residents. The study sample consisted of 591 Danish residents (50% women), aged 20-65, drawn from an age- and gender-stratified random sample of the Danish population. Participants filled out a survey that included the 92 item version of the Hopkins Symptom Checklist (SCL-92). We categorized occupational position into seven groups: high- and low-grade non-manual workers, skilled and unskilled manual workers, high- and low-grade self-employed, and unemployed. Compared to the reference group of high-grade non-manual workers, the depressive symptom score was statistically significantly elevated among unskilled manual workers (P = 0.043) and the unemployed (P < 0.001), after adjustment for age, gender, cohabitation, life events, and low household income. The anxiety symptom score was elevated only among the unemployed (P = 0.004). The somatization symptom score was elevated among unskilled manual workers (P = 0.002), the low-grade self-employed (P = 0.023), and the unemployed (P = 0.001). When we analyzed caseness of severe symptoms, we found that unskilled manual workers (OR = 3.27, 95% CI = 1.06-10.04) and the unemployed (OR = 6.20, 95% CI = 1.98-19.42) had a higher prevalence of severe depressive symptoms, compared to the reference group of high-grade non-manual workers. The unemployed also had a higher prevalence of severe somatization symptoms (OR = 6.28, 95% CI = 1.39-28.46). Unskilled manual workers, the unemployed, and, to a lesser extent, the low-grade self-employed showed an increased level of mental distress. Activities to promote mental health in the Danish population should be directed toward these groups.

  14. Dipolar eddies in a decaying stratified turbulent flow

    NASA Astrophysics Data System (ADS)

    Voropayev, S. I.; Fernando, H. J. S.; Morrison, R.

    2008-02-01

    Laboratory experiments on the evolution of dipolar (momentum) eddies in a stratified fluid in the presence of random background motions are described. A turbulent jet puff was used to generate the momentum eddies, and a decaying field of ambient random vortical motions was generated by a towed grid. Data on vorticity/velocity fields of momentum eddies, those of background motions, and their interactions were collected in the presence and absence of the other, and the main characteristics thereof were parametrized. Similarity arguments predict that dipolar eddies in stratified fluids may preserve their identity in decaying grid-generated stratified turbulence, which was verified experimentally. Possible applications of the results include mushroomlike currents and other naturally/artificially generated large dipolar eddies in strongly stratified layers of the ocean, the longevity of which is expected to be determined by the characteristics of the eddies and random background motions.

  15. Sample size estimation for alternating logistic regressions analysis of multilevel randomized community trials of under-age drinking.

    PubMed

    Reboussin, Beth A; Preisser, John S; Song, Eun-Young; Wolfson, Mark

    2012-07-01

    Under-age drinking is an enormous public health issue in the USA. Evidence that community level structures may impact on under-age drinking has led to a proliferation of efforts to change the environment surrounding the use of alcohol. Although the focus of these efforts is to reduce drinking by individual youths, environmental interventions are typically implemented at the community level with entire communities randomized to the same intervention condition. A distinct feature of these trials is the tendency of the behaviours of individuals residing in the same community to be more alike than that of others residing in different communities, which is herein called 'clustering'. Statistical analyses and sample size calculations must account for this clustering to avoid type I errors and to ensure an appropriately powered trial. Clustering itself may also be of scientific interest. We consider the alternating logistic regressions procedure within the population-averaged modelling framework to estimate the effect of a law enforcement intervention on the prevalence of under-age drinking behaviours while modelling the clustering at multiple levels, e.g. within communities and within neighbourhoods nested within communities, by using pairwise odds ratios. We then derive sample size formulae for estimating intervention effects when planning a post-test-only or repeated cross-sectional community-randomized trial using the alternating logistic regressions procedure.

  16. Forest resource inventory assessment in Gunung Rara Forest Reserve, Sabah, using stratified field sampling

    Treesearch

    Kamaruzaman Jusoff

    2000-01-01

    The objective of this paper is to assess the current timber volume by stratified sampling on a proposed plantation area. The study area is located in Gunung Rara Forest Reserve in the district of Tawau, Sabah, Malaysia.

  17. The influence factors of medical professionalism: A stratified-random sampling study based on the physicians and patients in ambulatory care clinics of Chengdu, China.

    PubMed

    Lin, Yifei; Yin, Senlin; Lai, Sike; Tang, Ji; Huang, Jin; Du, Liang

    2016-10-01

    As the relationship between physicians and patients deteriorated in China recently, medical conflicts occurred more frequently now. Physicians, to a certain extent, also take some responsibilities. Awareness of medical professionalism and its influence factors can be helpful to take targeted measures and alleviate the contradiction. Through a combination of physicians' self-assessment and patients' assessment in ambulatory care clinics in Chengdu, this research aims to evaluate the importance of medical professionalism in hospitals and explore the influence factors, hoping to provide decision-making references to improve this grim situation. From February to March, 2013, a cross-sectional study was conducted in 2 tier 3 hospitals, 5 tier 2 hospitals, and 10 community hospitals through a stratified-random sampling method on physicians and patients, at a ratio of 1/5. Questionnaires are adopted from a pilot study. A total of 382 physicians and 1910 patients were matched and surveyed. Regarding the medical professionalism, the scores of the self-assessment for physicians were 85.18 ± 7.267 out of 100 and the scores of patient-assessment were 57.66 ± 7.043 out of 70. The influence factors of self-assessment were physicians' working years (P = 0.003) and patients' complaints (P = 0.006), whereas the influence factors of patient-assessment were patients' ages (P = 0.001) and their physicians' working years (P < 0.01) and satisfaction on the payment mode (P = 0.006). Higher self-assessment on the medical professionalism was in accordance with physicians of more working years and no complaint history. Higher patient-assessment was in line with elder patients, the physicians' more working years, and higher satisfaction on the payment mode. Elder patients, encountering with physicians who worked more years in health care services or with higher satisfaction on the payment mode, contribute to higher scores in patient assessment part. The government should

  18. A stratified random survey of the proportion of poor quality oral artesunate sold at medicine outlets in the Lao PDR - implications for therapeutic failure and drug resistance.

    PubMed

    Sengaloundeth, Sivong; Green, Michael D; Fernández, Facundo M; Manolin, Ot; Phommavong, Khamlieng; Insixiengmay, Vongsavanh; Hampton, Christina Y; Nyadong, Leonard; Mildenhall, Dallas C; Hostetler, Dana; Khounsaknalath, Lamphet; Vongsack, Latsamy; Phompida, Samlane; Vanisaveth, Viengxay; Syhakhang, Lamphone; Newton, Paul N

    2009-07-28

    Counterfeit oral artesunate has been a major public health problem in mainland SE Asia, impeding malaria control. A countrywide stratified random survey was performed to determine the availability and quality of oral artesunate in pharmacies and outlets (shops selling medicines) in the Lao PDR (Laos). In 2003, 'mystery' shoppers were asked to buy artesunate tablets from 180 outlets in 12 of the 18 Lao provinces. Outlets were selected using stratified random sampling by investigators not involved in sampling. Samples were analysed for packaging characteristics, by the Fast Red Dye test, high-performance liquid chromatography (HPLC), mass spectrometry (MS), X-ray diffractometry and pollen analysis. Of 180 outlets sampled, 25 (13.9%) sold oral artesunate. Outlets selling artesunate were more commonly found in the more malarious southern Laos. Of the 25 outlets, 22 (88%; 95%CI 68-97%) sold counterfeit artesunate, as defined by packaging and chemistry. No artesunate was detected in the counterfeits by any of the chemical analysis techniques and analysis of the packaging demonstrated seven different counterfeit types. There was complete agreement between the Fast Red dye test, HPLC and MS analysis. A wide variety of wrong active ingredients were found by MS. Of great concern, 4/27 (14.8%) fakes contained detectable amounts of artemisinin (0.26-115.7 mg/tablet). This random survey confirms results from previous convenience surveys that counterfeit artesunate is a severe public health problem. The presence of artemisinin in counterfeits may encourage malaria resistance to artemisinin derivatives. With increasing accessibility of artemisinin-derivative combination therapy (ACT) in Laos, the removal of artesunate monotherapy from pharmacies may be an effective intervention.

  19. Methods and analysis of realizing randomized grouping.

    PubMed

    Hu, Liang-Ping; Bao, Xiao-Lei; Wang, Qi

    2011-07-01

    Randomization is one of the four basic principles of research design. The meaning of randomization includes two aspects: one is to randomly select samples from the population, which is known as random sampling; the other is to randomly group all the samples, which is called randomized grouping. Randomized grouping can be subdivided into three categories: completely, stratified and dynamically randomized grouping. This article mainly introduces the steps of complete randomization, the definition of dynamic randomization and the realization of random sampling and grouping by SAS software.

  20. Risk-Stratified Imputation in Survival Analysis

    PubMed Central

    Kennedy, Richard E.; Adragni, Kofi P.; Tiwari, Hemant K.; Voeks, Jenifer H.; Brott, Thomas G.; Howard, George

    2013-01-01

    Background Censoring that is dependent on covariates associated with survival can arise in randomized trials due to changes in recruitment and eligibility criteria to minimize withdrawals, potentially leading to biased treatment effect estimates. Imputation approaches have been proposed to address censoring in survival analysis; and while these approaches may provide unbiased estimates of treatment effects, imputation of a large number of outcomes may over- or underestimate the associated variance based on the imputation pool selected. Purpose We propose an improved method, risk-stratified imputation, as an alternative to address withdrawal related to the risk of events in the context of time-to-event analyses. Methods Our algorithm performs imputation from a pool of replacement subjects with similar values of both treatment and covariate(s) of interest, that is, from a risk-stratified sample. This stratification prior to imputation addresses the requirement of time-to-event analysis that censored observations are representative of all other observations in the risk group with similar exposure variables. We compared our risk-stratified imputation to case deletion and bootstrap imputation in a simulated dataset in which the covariate of interest (study withdrawal) was related to treatment. A motivating example from a recent clinical trial is also presented to demonstrate the utility of our method. Results In our simulations, risk-stratified imputation gives estimates of treatment effect comparable to bootstrap and auxiliary variable imputation while avoiding inaccuracies of the latter two in estimating the associated variance. Similar results were obtained in analysis of clinical trial data. Limitations Risk-stratified imputation has little advantage over other imputation methods when covariates of interest are not related to treatment, although its performance is superior when covariates are related to treatment. Risk-stratified imputation is intended for

  1. A stratified random survey of the proportion of poor quality oral artesunate sold at medicine outlets in the Lao PDR – implications for therapeutic failure and drug resistance

    PubMed Central

    Sengaloundeth, Sivong; Green, Michael D; Fernández, Facundo M; Manolin, Ot; Phommavong, Khamlieng; Insixiengmay, Vongsavanh; Hampton, Christina Y; Nyadong, Leonard; Mildenhall, Dallas C; Hostetler, Dana; Khounsaknalath, Lamphet; Vongsack, Latsamy; Phompida, Samlane; Vanisaveth, Viengxay; Syhakhang, Lamphone; Newton, Paul N

    2009-01-01

    Background Counterfeit oral artesunate has been a major public health problem in mainland SE Asia, impeding malaria control. A countrywide stratified random survey was performed to determine the availability and quality of oral artesunate in pharmacies and outlets (shops selling medicines) in the Lao PDR (Laos). Methods In 2003, 'mystery' shoppers were asked to buy artesunate tablets from 180 outlets in 12 of the 18 Lao provinces. Outlets were selected using stratified random sampling by investigators not involved in sampling. Samples were analysed for packaging characteristics, by the Fast Red Dye test, high-performance liquid chromatography (HPLC), mass spectrometry (MS), X-ray diffractometry and pollen analysis. Results Of 180 outlets sampled, 25 (13.9%) sold oral artesunate. Outlets selling artesunate were more commonly found in the more malarious southern Laos. Of the 25 outlets, 22 (88%; 95%CI 68–97%) sold counterfeit artesunate, as defined by packaging and chemistry. No artesunate was detected in the counterfeits by any of the chemical analysis techniques and analysis of the packaging demonstrated seven different counterfeit types. There was complete agreement between the Fast Red dye test, HPLC and MS analysis. A wide variety of wrong active ingredients were found by MS. Of great concern, 4/27 (14.8%) fakes contained detectable amounts of artemisinin (0.26–115.7 mg/tablet). Conclusion This random survey confirms results from previous convenience surveys that counterfeit artesunate is a severe public health problem. The presence of artemisinin in counterfeits may encourage malaria resistance to artemisinin derivatives. With increasing accessibility of artemisinin-derivative combination therapy (ACT) in Laos, the removal of artesunate monotherapy from pharmacies may be an effective intervention. PMID:19638225

  2. Estimation of infection prevalence and sensitivity in a stratified two-stage sampling design employing highly specific diagnostic tests when there is no gold standard.

    PubMed

    Miller, Ezer; Huppert, Amit; Novikov, Ilya; Warburg, Alon; Hailu, Asrat; Abbasi, Ibrahim; Freedman, Laurence S

    2015-11-10

    In this work, we describe a two-stage sampling design to estimate the infection prevalence in a population. In the first stage, an imperfect diagnostic test was performed on a random sample of the population. In the second stage, a different imperfect test was performed in a stratified random sample of the first sample. To estimate infection prevalence, we assumed conditional independence between the diagnostic tests and develop method of moments estimators based on expectations of the proportions of people with positive and negative results on both tests that are functions of the tests' sensitivity, specificity, and the infection prevalence. A closed-form solution of the estimating equations was obtained assuming a specificity of 100% for both tests. We applied our method to estimate the infection prevalence of visceral leishmaniasis according to two quantitative polymerase chain reaction tests performed on blood samples taken from 4756 patients in northern Ethiopia. The sensitivities of the tests were also estimated, as well as the standard errors of all estimates, using a parametric bootstrap. We also examined the impact of departures from our assumptions of 100% specificity and conditional independence on the estimated prevalence. Copyright © 2015 John Wiley & Sons, Ltd.

  3. An aging population: relationships between socio-demographics, motivations and participation

    Treesearch

    Karen Robinson; Robert C. Burns; Chad D. Pierskalla; Alan Graefe

    2008-01-01

    The purpose of this study was to examine the outdoor recreation behavior of Oregon's aging population, including developing a socio-demographic profile and examining the importance of their current motivations with the importance of their expected motivations 10 years from now. A stratified random sample was drawn of Oregon residents, and a mailback questionnaire...

  4. A comparison of selection at list time and time-stratified sampling for estimating suspended sediment loads

    Treesearch

    Robert B. Thomas; Jack Lewis

    1993-01-01

    Time-stratified sampling of sediment for estimating suspended load is introduced and compared to selection at list time (SALT) sampling. Both methods provide unbiased estimates of load and variance. The magnitude of the variance of the two methods is compared using five storm populations of suspended sediment flux derived from turbidity data. Under like conditions,...

  5. Sampling Strategies for Evaluating the Rate of Adventitious Transgene Presence in Non-Genetically Modified Crop Fields.

    PubMed

    Makowski, David; Bancal, Rémi; Bensadoun, Arnaud; Monod, Hervé; Messéan, Antoine

    2017-09-01

    According to E.U. regulations, the maximum allowable rate of adventitious transgene presence in non-genetically modified (GM) crops is 0.9%. We compared four sampling methods for the detection of transgenic material in agricultural non-GM maize fields: random sampling, stratified sampling, random sampling + ratio reweighting, random sampling + regression reweighting. Random sampling involves simply sampling maize grains from different locations selected at random from the field concerned. The stratified and reweighting sampling methods make use of an auxiliary variable corresponding to the output of a gene-flow model (a zero-inflated Poisson model) simulating cross-pollination as a function of wind speed, wind direction, and distance to the closest GM maize field. With the stratified sampling method, an auxiliary variable is used to define several strata with contrasting transgene presence rates, and grains are then sampled at random from each stratum. With the two methods involving reweighting, grains are first sampled at random from various locations within the field, and the observations are then reweighted according to the auxiliary variable. Data collected from three maize fields were used to compare the four sampling methods, and the results were used to determine the extent to which transgene presence rate estimation was improved by the use of stratified and reweighting sampling methods. We found that transgene rate estimates were more accurate and that substantially smaller samples could be used with sampling strategies based on an auxiliary variable derived from a gene-flow model. © 2017 Society for Risk Analysis.

  6. [Comparison study on sampling methods of Oncomelania hupensis snail survey in marshland schistosomiasis epidemic areas in China].

    PubMed

    An, Zhao; Wen-Xin, Zhang; Zhong, Yao; Yu-Kuan, Ma; Qing, Liu; Hou-Lang, Duan; Yi-di, Shang

    2016-06-29

    To optimize and simplify the survey method of Oncomelania hupensis snail in marshland endemic region of schistosomiasis and increase the precision, efficiency and economy of the snail survey. A quadrate experimental field was selected as the subject of 50 m×50 m size in Chayegang marshland near Henghu farm in the Poyang Lake region and a whole-covered method was adopted to survey the snails. The simple random sampling, systematic sampling and stratified random sampling methods were applied to calculate the minimum sample size, relative sampling error and absolute sampling error. The minimum sample sizes of the simple random sampling, systematic sampling and stratified random sampling methods were 300, 300 and 225, respectively. The relative sampling errors of three methods were all less than 15%. The absolute sampling errors were 0.221 7, 0.302 4 and 0.047 8, respectively. The spatial stratified sampling with altitude as the stratum variable is an efficient approach of lower cost and higher precision for the snail survey.

  7. Influence of population versus convenience sampling on sample characteristics in studies of cognitive aging.

    PubMed

    Brodaty, Henry; Mothakunnel, Annu; de Vel-Palumbo, Melissa; Ames, David; Ellis, Kathryn A; Reppermund, Simone; Kochan, Nicole A; Savage, Greg; Trollor, Julian N; Crawford, John; Sachdev, Perminder S

    2014-01-01

    We examined whether differences in findings of studies examining mild cognitive impairment (MCI) were associated with recruitment methods by comparing sample characteristics in two contemporaneous Australian studies, using population-based and convenience sampling. The Sydney Memory and Aging Study invited participants randomly from the electoral roll in defined geographic areas in Sydney. The Australian Imaging, Biomarkers and Lifestyle Study of Ageing recruited cognitively normal (CN) individuals via media appeals and MCI participants via referrals from clinicians in Melbourne and Perth. Demographic and cognitive variables were harmonized, and similar diagnostic criteria were applied to both samples retrospectively. CN participants recruited via convenience sampling were younger, better educated, more likely to be married and have a family history of dementia, and performed better cognitively than those recruited via population-based sampling. MCI participants recruited via population-based sampling had better memory performance and were less likely to carry the apolipoprotein E ε4 allele than clinically referred participants but did not differ on other demographic variables. A convenience sample of normal controls is likely to be younger and better functioning and that of an MCI group likely to perform worse than a purportedly random sample. Sampling bias should be considered when interpreting findings. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. A random cluster survey and a convenience sample give comparable estimates of immunity to vaccine preventable diseases in children of school age in Victoria, Australia.

    PubMed

    Kelly, Heath; Riddell, Michaela A; Gidding, Heather F; Nolan, Terry; Gilbert, Gwendolyn L

    2002-08-19

    We compared estimates of the age-specific population immunity to measles, mumps, rubella, hepatitis B and varicella zoster viruses in Victorian school children obtained by a national sero-survey, using a convenience sample of residual sera from diagnostic laboratories throughout Australia, with those from a three-stage random cluster survey. When grouped according to school age (primary or secondary school) there was no significant difference in the estimates of immunity to measles, mumps, hepatitis B or varicella. Compared with the convenience sample, the random cluster survey estimated higher immunity to rubella in samples from both primary (98.7% versus 93.6%, P = 0.002) and secondary school students (98.4% versus 93.2%, P = 0.03). Despite some limitations, this study suggests that the collection of a convenience sample of sera from diagnostic laboratories is an appropriate sampling strategy to provide population immunity data that will inform Australia's current and future immunisation policies. Copyright 2002 Elsevier Science Ltd.

  9. Randomized branch sampling

    Treesearch

    Harry T. Valentine

    2002-01-01

    Randomized branch sampling (RBS) is a special application of multistage probability sampling (see Sampling, environmental), which was developed originally by Jessen [3] to estimate fruit counts on individual orchard trees. In general, the method can be used to obtain estimates of many different attributes of trees or other branched plants. The usual objective of RBS is...

  10. Effectiveness of a two-step population-based osteoporosis screening program using FRAX: the randomized Risk-stratified Osteoporosis Strategy Evaluation (ROSE) study.

    PubMed

    Rubin, K H; Rothmann, M J; Holmberg, T; Høiberg, M; Möller, S; Barkmann, R; Glüer, C C; Hermann, A P; Bech, M; Gram, J; Brixen, K

    2018-03-01

    The Risk-stratified Osteoporosis Strategy Evaluation (ROSE) study investigated the effectiveness of a two-step screening program for osteoporosis in women. We found no overall reduction in fractures from systematic screening compared to the current case-finding strategy. The group of moderate- to high-risk women, who accepted the invitation to DXA, seemed to benefit from the program. The purpose of the ROSE study was to investigate the effectiveness of a two-step population-based osteoporosis screening program using the Fracture Risk Assessment Tool (FRAX) derived from a self-administered questionnaire to select women for DXA scan. After the scanning, standard osteoporosis management according to Danish national guidelines was followed. Participants were randomized to either screening or control group, and randomization was stratified according to age and area of residence. Inclusion took place from February 2010 to November 2011. Participants received a self-administered questionnaire, and women in the screening group with a FRAX score ≥ 15% (major osteoporotic fractures) were invited to a DXA scan. Primary outcome was incident clinical fractures. Intention-to-treat analysis and two per-protocol analyses were performed. A total of 3416 fractures were observed during a median follow-up of 5 years. No significant differences were found in the intention-to-treat analyses with 34,229 women included aged 65-80 years. The per-protocol analyses showed a risk reduction in the group that underwent DXA scanning compared to women in the control group with a FRAX ≥ 15%, in regard to major osteoporotic fractures, hip fractures, and all fractures. The risk reduction was most pronounced for hip fractures (adjusted SHR 0.741, p = 0.007). Compared to an office-based case-finding strategy, the two-step systematic screening strategy had no overall effect on fracture incidence. The two-step strategy seemed, however, to be beneficial in the group of women who were

  11. Systematic versus random sampling in stereological studies.

    PubMed

    West, Mark J

    2012-12-01

    The sampling that takes place at all levels of an experimental design must be random if the estimate is to be unbiased in a statistical sense. There are two fundamental ways by which one can make a random sample of the sections and positions to be probed on the sections. Using a card-sampling analogy, one can pick any card at all out of a deck of cards. This is referred to as independent random sampling because the sampling of any one card is made without reference to the position of the other cards. The other approach to obtaining a random sample would be to pick a card within a set number of cards and others at equal intervals within the deck. Systematic sampling along one axis of many biological structures is more efficient than random sampling, because most biological structures are not randomly organized. This article discusses the merits of systematic versus random sampling in stereological studies.

  12. Optimal spatial sampling techniques for ground truth data in microwave remote sensing of soil moisture

    NASA Technical Reports Server (NTRS)

    Rao, R. G. S.; Ulaby, F. T.

    1977-01-01

    The paper examines optimal sampling techniques for obtaining accurate spatial averages of soil moisture, at various depths and for cell sizes in the range 2.5-40 acres, with a minimum number of samples. Both simple random sampling and stratified sampling procedures are used to reach a set of recommended sample sizes for each depth and for each cell size. Major conclusions from statistical sampling test results are that (1) the number of samples required decreases with increasing depth; (2) when the total number of samples cannot be prespecified or the moisture in only one single layer is of interest, then a simple random sample procedure should be used which is based on the observed mean and SD for data from a single field; (3) when the total number of samples can be prespecified and the objective is to measure the soil moisture profile with depth, then stratified random sampling based on optimal allocation should be used; and (4) decreasing the sensor resolution cell size leads to fairly large decreases in samples sizes with stratified sampling procedures, whereas only a moderate decrease is obtained in simple random sampling procedures.

  13. Usefulness of Age-Stratified N-Terminal Prohormone of Brain Natriuretic Peptide for Diagnosing Kawasaki Disease

    PubMed Central

    Lee, Sang Hoon; Yoon, Somy; Hong, Seunghee; Yang, Eun Mi; Eom, Gwang Hyeon

    2017-01-01

    N-terminal prohormone of brain natriuretic peptide (NT-proBNP) was recently reported as a biomarker for diagnosing Kawasaki disease (KD). The basal NT-proBNP level, however, gradually decreases with age. We investigated the usefulness of an age-stratified cutoff value of NT-proBNP for diagnosing KD. All the patients enrolled in this study visited Chonnam National University Hospital between December 2007 and March 2016. The KD groups consisted of 214 patients with complete KD and 129 patients with incomplete KD. The control group included 62 children with simple febrile illness but without heart disease. Laboratory data including NT-proBNP level were evaluated. Each group was divided into subgroups according to patient age (<6 months, 6–12 months, 12–24 months, and >24 months), and different cutoff values of NT-proBNP were calculated. The cutoff values of NT-proBNP used to diagnose total KD and incomplete KD were 762 and 762 pg/mL (<6 months), 310 and 310 pg/mL (6–12 months), 326 and 326 pg/mL (12–24 months), and 208 and 137 pg/mL (>24 months), respectively. In conclusion, age-stratified NT-proBNP is a useful biomarker for the differential diagnosis of KD in patients with a simple febrile illness. PMID:29358841

  14. Sampling error in timber surveys

    Treesearch

    Austin Hasel

    1938-01-01

    Various sampling strategies are evaluated for efficiency in an interior ponderosa pine forest. In a 5760 acre tract, efficiency was gained by stratifying into quarter acre blocks and sampling randomly from within. A systematic cruise was found to be superior for volume estimation.

  15. The Effect Of Age At Harvest On Bending And Tensile Properties Of Loblolly Pine From The Coastal Plain

    Treesearch

    Robert H. McAlister; Alexander Clark; Joseph R. Saucier

    1997-01-01

    The effect of rotation age on strength and stiffness of lumber produced from unthinned loblolly pine stands in the Coastal Plain of Georgia was examined. Six stands representing 22-, 28-, and 40-year-old roations were sampled. A stratified random sample of trees 8 to 16 inches in diameter at breast height was selected from each stand and processed into lumber....

  16. Sampling estimators of total mill receipts for use in timber product output studies

    Treesearch

    John P. Brown; Richard G. Oderwald

    2012-01-01

    Data from the 2001 timber product output study for Georgia was explored to determine new methods for stratifying mills and finding suitable sampling estimators. Estimators for roundwood receipts totals comprised several types: simple random sample, ratio, stratified sample, and combined ratio. Two stratification methods were examined: the Dalenius-Hodges (DH) square...

  17. Omega-3 (ω-3) and social skills interventions for reactive aggression and childhood externalizing behavior problems: a randomized, stratified, double-blind, placebo-controlled, factorial trial.

    PubMed

    Raine, Adrian; Ang, Rebecca P; Choy, Olivia; Hibbeln, Joseph R; Ho, Ringo M-H; Lim, Choon Guan; Lim-Ashworth, Nikki S J; Ling, Shichun; Liu, Jean C J; Ooi, Yoon Phaik; Tan, Yi Ren; Fung, Daniel S S

    2018-05-10

    While studies suggest that nutritional supplementation may reduce aggressive behavior in children, few have examined their effects on specific forms of aggression. This study tests the primary hypothesis that omega-3 (ω-3), both alone and in conjunction with social skills training, will have particular post-treatment efficacy for reducing childhood reactive aggression relative to baseline. In this randomized, double-blind, stratified, placebo-controlled, factorial trial, a clinical sample of 282 children with externalizing behavior aged 7-16 years was randomized into ω-3 only, social skills only, ω-3 + social skills, and placebo control groups. Treatment duration was 6 months. The primary outcome measure was reactive aggression collected at 0, 3, 6, 9, and 12 months, with antisocial behavior as a secondary outcome. Children in the ω-3-only group showed a short-term reduction (at 3 and 6 months) in self-report reactive aggression, and also a short-term reduction in overall antisocial behavior. Sensitivity analyses and a robustness check replicated significant interaction effects. Effect sizes (d) were small, ranging from 0.17 to 0.31. Findings provide some initial support for the efficacy of ω-3 in reducing reactive aggression over and above standard care (medication and parent training), but yield only preliminary and limited support for the efficacy of ω-3 in reducing overall externalizing behavior in children. Future studies could test further whether ω-3 shows promise in reducing more reactive, impulsive forms of aggression.

  18. Design of dry sand soil stratified sampler

    NASA Astrophysics Data System (ADS)

    Li, Erkang; Chen, Wei; Feng, Xiao; Liao, Hongbo; Liang, Xiaodong

    2018-04-01

    This paper presents a design of a stratified sampler for dry sand soil, which can be used for stratified sampling of loose sand under certain conditions. Our group designed the mechanical structure of a portable, single - person, dry sandy soil stratified sampler. We have set up a mathematical model for the sampler. It lays the foundation for further development of design research.

  19. RECAL: A Computer Program for Selecting Sample Days for Recreation Use Estimation

    Treesearch

    D.L. Erickson; C.J. Liu; H. Ken Cordell; W.L. Chen

    1980-01-01

    Recreation Calendar (RECAL) is a computer program in PL/I for drawing a sample of days for estimating recreation use. With RECAL, a sampling period of any length may be chosen; simple random, stratified random, and factorial designs can be accommodated. The program randomly allocates days to strata and locations.

  20. Sparsely sampling the sky: Regular vs. random sampling

    NASA Astrophysics Data System (ADS)

    Paykari, P.; Pires, S.; Starck, J.-L.; Jaffe, A. H.

    2015-09-01

    Aims: The next generation of galaxy surveys, aiming to observe millions of galaxies, are expensive both in time and money. This raises questions regarding the optimal investment of this time and money for future surveys. In a previous work, we have shown that a sparse sampling strategy could be a powerful substitute for the - usually favoured - contiguous observation of the sky. In our previous paper, regular sparse sampling was investigated, where the sparse observed patches were regularly distributed on the sky. The regularity of the mask introduces a periodic pattern in the window function, which induces periodic correlations at specific scales. Methods: In this paper, we use a Bayesian experimental design to investigate a "random" sparse sampling approach, where the observed patches are randomly distributed over the total sparsely sampled area. Results: We find that in this setting, the induced correlation is evenly distributed amongst all scales as there is no preferred scale in the window function. Conclusions: This is desirable when we are interested in any specific scale in the galaxy power spectrum, such as the matter-radiation equality scale. As the figure of merit shows, however, there is no preference between regular and random sampling to constrain the overall galaxy power spectrum and the cosmological parameters.

  1. Properties of the endogenous post-stratified estimator using a random forests model

    Treesearch

    John Tipton; Jean Opsomer; Gretchen G. Moisen

    2012-01-01

    Post-stratification is used in survey statistics as a method to improve variance estimates. In traditional post-stratification methods, the variable on which the data is being stratified must be known at the population level. In many cases this is not possible, but it is possible to use a model to predict values using covariates, and then stratify on these predicted...

  2. Accuracy Sampling Design Bias on Coarse Spatial Resolution Land Cover Data in the Great Lakes Region (United States and Canada)

    EPA Science Inventory

    A number of articles have investigated the impact of sampling design on remotely sensed landcover accuracy estimates. Gong and Howarth (1990) found significant differences for Kappa accuracy values when comparing purepixel sampling, stratified random sampling, and stratified sys...

  3. Enhancing Asthma Self-Management in Rural School-Aged Children: A Randomized Controlled Trial.

    PubMed

    Horner, Sharon D; Brown, Adama; Brown, Sharon A; Rew, D Lynn

    2016-06-01

    To test the effects of 2 modes of delivering an asthma educational intervention on health outcomes and asthma self-management in school-aged children who live in rural areas. Longitudinal design with data collected 4 times over 12 months. The target sample was composed of children in grades 2-5 who had a provider diagnosis of asthma. Elementary schools were stratified into high or low socioeconomic status based on student enrollment in the free or reduced-cost lunch program. Schools were then randomly assigned to 1 of 3 treatment arms: in-school asthma class, asthma day camp, or the attention-control group. Sample retention was good (87.7%) and equally distributed by study arm. Improvements in emergency department visits and office visits were related to attending either the asthma class or asthma day camp. Asthma severity significantly decreased in both asthma treatment groups. Other factors such as hospitalizations, parent asthma management, and child asthma management improved for all groups. Both asthma class and asthma day camp yielded significant reductions in asthma severity. There were reductions in the emergency department and office visits for the 2 asthma arms, and hospitalizations declined significantly for all groups. Asthma self-management also improved in all groups, while it was somewhat higher in the asthma arms. This may be due to the attention being drawn to asthma management by study participation and the action of completing questionnaires about asthma management, asthma symptoms, and health outcomes. © 2015 National Rural Health Association.

  4. Using random telephone sampling to recruit generalizable samples for family violence studies.

    PubMed

    Slep, Amy M Smith; Heyman, Richard E; Williams, Mathew C; Van Dyke, Cheryl E; O'Leary, Susan G

    2006-12-01

    Convenience sampling methods predominate in recruiting for laboratory-based studies within clinical and family psychology. The authors used random digit dialing (RDD) to determine whether they could feasibly recruit generalizable samples for 2 studies (a parenting study and an intimate partner violence study). RDD screen response rate was 42-45%; demographics matched those in the 2000 U.S. Census, with small- to medium-sized differences on race, age, and income variables. RDD respondents who qualified for, but did not participate in, the laboratory study of parents showed small differences on income, couple conflicts, and corporal punishment. Time and cost are detailed, suggesting that RDD may be a feasible, effective method by which to recruit more generalizable samples for in-laboratory studies of family violence when those studies have sufficient resources. (c) 2006 APA, all rights reserved.

  5. Is a 'convenience' sample useful for estimating immunization coverage in a small population?

    PubMed

    Weir, Jean E; Jones, Carrie

    2008-01-01

    Rapid survey methodologies are widely used for assessing immunization coverage in developing countries, approximating true stratified random sampling. Non-random ('convenience') sampling is not considered appropriate for estimating immunization coverage rates but has the advantages of low cost and expediency. We assessed the validity of a convenience sample of children presenting to a travelling clinic by comparing the coverage rate in the convenience sample to the true coverage established by surveying each child in three villages in rural Papua New Guinea. The rate of DTF immunization coverage as estimated by the convenience sample was within 10% of the true coverage when the proportion of children in the sample was two-thirds or when only children over the age of one year were counted, but differed by 11% when the sample included only 53% of the children and when all eligible children were included. The convenience sample may be sufficiently accurate for reporting purposes and is useful for identifying areas of low coverage.

  6. Reduction of display artifacts by random sampling

    NASA Technical Reports Server (NTRS)

    Ahumada, A. J., Jr.; Nagel, D. C.; Watson, A. B.; Yellott, J. I., Jr.

    1983-01-01

    The application of random-sampling techniques to remove visible artifacts (such as flicker, moire patterns, and paradoxical motion) introduced in TV-type displays by discrete sequential scanning is discussed and demonstrated. Sequential-scanning artifacts are described; the window of visibility defined in spatiotemporal frequency space by Watson and Ahumada (1982 and 1983) and Watson et al. (1983) is explained; the basic principles of random sampling are reviewed and illustrated by the case of the human retina; and it is proposed that the sampling artifacts can be replaced by random noise, which can then be shifted to frequency-space regions outside the window of visibility. Vertical sequential, single-random-sequence, and continuously renewed random-sequence plotting displays generating 128 points at update rates up to 130 Hz are applied to images of stationary and moving lines, and best results are obtained with the single random sequence for the stationary lines and with the renewed random sequence for the moving lines.

  7. [MESGI50 study: description of a cohort on Maturity and Satisfactory Ageing].

    PubMed

    Corominas Barnadas, Josep María; López-Pousa, Secundino; Vilalta-Franch, Joan; Calvó-Perxas, Laia; Juvinyà Canal, Dolors; Garre-Olmo, Josep

    To describe the demographic, health and socio-economic characteristics of the participants in the Study on Maturity and Satisfactory Ageing in Girona (MESGI50 study). Population-based Study linked to the Survey of Health, Ageing, and Retirement in Europe (SHARE). The reference population was the inhabitants of the province of Girona (Spain) aged 50 and over. A probabilistic two-stage stratified cluster sampling according to the number of inhabitants and the degree of ageing of the population was used. Twenty-eight municipalities were randomly selected according to their type (demographically aged or young), and then stratified by the population size. The response rate was 65% with a mean of 1.7 eligible individuals per household and a final sample of 2,065 households and 3,331 participants. The design effect was 1.27. 52.9% were women and the mean age was 66.9 years (SD=11.5). The self-rated health status, hand grip strength, restriction in daily life activities and depressive symptomatology increased with age and more markedly in women. There were differences in alcohol consumption and eating patterns depending on the area of residence. The demographic, health and socio-economic characteristics during the ageing process differ depending on age group, gender, and area of residence. Copyright © 2016 SESPAS. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. Familial clustering in subgroups of gastric cancer stratified by histology, age group and location.

    PubMed

    Eto, K; Ohyama, S; Yamaguchi, T; Wada, T; Suzuki, Y; Mitsumori, N; Kashiwagi, H; Anazawa, S; Yanaga, K; Urashima, M

    2006-09-01

    To assess the risk of gastric cancer in a Japanese patient population with the disease by stratification with histology, age, tumour location and the association with family history of gastric or non-gastric tumours. A retrospective analysis of 1400 consecutive patients with gastric cancer and 13,467 age- and gender-matched controls from a pre-recorded database using conditional logistic regression models. Young patients (< or = 43 years of age) with gastric cancer of intestinal type had a strong association with family history of gastric cancer in first degree-relatives (OR=12.5). Moreover, when a history of gastric cancer was observed in both parents, there was an increased risk of gastric cancer intestinal type (OR=7.8), more commonly in the proximal and mid-stomach. In contrast, there was an increased risk of diffuse-type cancer when both parents suffered non-gastric cancers (OR=2.1). These data suggest that the degree of familial clustering differ in gastric cancer subgroups stratified by histology, age, and stomach location in this Japanese population.

  9. Age-specific seroprevalence of dengue infection in Hong Kong.

    PubMed

    Lee, Polly; Yeung, Apple C M; Chen, Zigui; Chan, Martin C W; Sze, Kin Ho; Chan, Paul K S

    2018-05-02

    A newly developed dengue virus vaccine (chimeric yellow fever virus-tetravalent dengue vaccine [CYD-TDV]) has recently been licensed for clinical use. The World Health Organization recommends vaccination for populations with seroprevalence of at least 70% to maximize public health impact. This study aimed to delineate the seroprevalence of dengue infection in Hong Kong. A total of 105 972 serum samples submitted for clinical testing during the period 2013-2015 were age-stratified and sex-stratified. For each year of collection, 25 samples were randomly selected from each age-sex group. Altogether, 2100 samples were tested for the dengue immunoglobulin G (IgG) antibody using a non-type-specific ELISA kit. The overall dengue IgG-positive rate was 4.6% and showed no significant change over the 3 years. The positive rate was not associated with sex, but a steep rise in seroprevalence for persons above 65 years (32.7%) was observed. The low dengue seroprevalence in Hong Kong does not support implementation of a national immunization program. Majority of the population in Hong Kong are susceptible to dengue infection, and a substantial proportion of persons older than 65 years could acquire secondary infection and are prone to develop severe dengue. © 2018 Wiley Periodicals, Inc.

  10. Single-particle dispersion in stably stratified turbulence

    NASA Astrophysics Data System (ADS)

    Sujovolsky, N. E.; Mininni, P. D.; Rast, M. P.

    2018-03-01

    We present models for single-particle dispersion in vertical and horizontal directions of stably stratified flows. The model in the vertical direction is based on the observed Lagrangian spectrum of the vertical velocity, while the model in the horizontal direction is a combination of a continuous-time eddy-constrained random walk process with a contribution to transport from horizontal winds. Transport at times larger than the Lagrangian turnover time is not universal and dependent on these winds. The models yield results in good agreement with direct numerical simulations of stratified turbulence, for which single-particle dispersion differs from the well-studied case of homogeneous and isotropic turbulence.

  11. A Nationwide Random Sampling Survey of Potential Complicated Grief in Japan

    ERIC Educational Resources Information Center

    Mizuno, Yasunao; Kishimoto, Junji; Asukai, Nozomu

    2012-01-01

    To investigate the prevalence of significant loss, potential complicated grief (CG), and its contributing factors, we conducted a nationwide random sampling survey of Japanese adults aged 18 or older (N = 1,343) using a self-rating Japanese-language version of the Complicated Grief Brief Screen. Among them, 37.0% experienced their most significant…

  12. Seroprevalence and some correlates of Helicobacter pylori at adult ages in Gülveren Health District, Ankara, Turkey.

    PubMed Central

    Akin, L.; Tezcan, S.; Hascelik, G.; Cakir, B.

    2004-01-01

    The purpose of the study was to detect the frequency and distribution of Helicobacter pylori in the Gülveren Health Centre service area among residents aged between 25 and 64 years and to evaluate the relation of H. pylori infections with general health status, socioeconomic status, and some lifestyle habits. The study included a representative sample of Gülveren Health Centre residents, aged between 25 and 64 years. A stratified random sample of 1672 individuals was selected for study purposes out of 10,569 residents, stratified by age and gender. A standardized questionnaire was completed for all study participants using a face-to-face interview and all participants were invited to the local health centre for a thorough physical examination and blood tests. The overall prevalence of H. pylori was found to be 77.5 % among individuals aged between 25 and 64 years. The frequency of H. pylori was higher among individuals with low socioeconomic status; those who migrated to Ankara after the age of 20 years; members of large families (household size of 4 or above); non-alcohol drinkers; and those who regularly drink tea. PMID:15473147

  13. Determinants of serum zinc in a random population sample of four Belgian towns with different degrees of environmental exposure to cadmium

    PubMed Central

    Thijs, Lutgarde; Staessen, Jan; Amery, Antoon; Bruaux, Pierre; Buchet, Jean-Pierre; Claeys, FranÇoise; De Plaen, Pierre; Ducoffre, Geneviève; Lauwerys, Robert; Lijnen, Paul; Nick, Laurence; Remy, Annie Saint; Roels, Harry; Rondia, Désiré; Sartor, Francis

    1992-01-01

    This report investigated the distribution of serum zinc and the factors determining serum zinc concentration in a large random population sample. The 1977 participants (959 men and 1018 women), 20–80 years old, constituted a stratified random sample of the population of four Belgian districts, representing two areas with low and two with high environmental exposure to cadmium. For each exposure level, a rural and an urban area were selected. The serum concentration of zinc, frequently used as an index for zinc status in human subjects, was higher in men (13.1 μmole/L, range 6.5–23.0 μmole/L) than in women (12.6 μmole/L, range 6.3–23.2 μmole/L). In men, 20% of the variance of serum zinc was explained by age (linear and squared term, R = 0.29), diurnal variation (r = 0.29), and total cholesterol (r = 0.16). After adjustment for these covariates, a negative relationship was observed between serum zinc and both blood (r = −0.10) and urinary cadmium (r = −0.14). In women, 11% of the variance could be explained by age (linear and squared term, R = 0.15), diurnal variation in serum zinc (r = 0.27), creatinine clearance (r = −0.11), log γ-glutamyltranspeptidase (r = 0.08), cholesterol (r = 0.07), contraceptive pill intake (r = −0.07), and log serum ferritin (r = 0.06). Before and after adjustment for significant covariates, serum zinc was, on average, lowest in the two districts where the body burden of cadmium, as assessed by urinary cadmium excretion, was highest. These results were not altered when subjects exposed to heavy metals at work were excluded from analysis. PMID:1486857

  14. CTEPP STANDARD OPERATING PROCEDURE FOR SAMPLE SELECTION (SOP-1.10)

    EPA Science Inventory

    The procedures for selecting CTEPP study subjects are described in the SOP. The primary, county-level stratification is by region and urbanicity. Six sample counties in each of the two states (North Carolina and Ohio) are selected using stratified random sampling and reflect ...

  15. Improved Compressive Sensing of Natural Scenes Using Localized Random Sampling

    PubMed Central

    Barranca, Victor J.; Kovačič, Gregor; Zhou, Douglas; Cai, David

    2016-01-01

    Compressive sensing (CS) theory demonstrates that by using uniformly-random sampling, rather than uniformly-spaced sampling, higher quality image reconstructions are often achievable. Considering that the structure of sampling protocols has such a profound impact on the quality of image reconstructions, we formulate a new sampling scheme motivated by physiological receptive field structure, localized random sampling, which yields significantly improved CS image reconstructions. For each set of localized image measurements, our sampling method first randomly selects an image pixel and then measures its nearby pixels with probability depending on their distance from the initially selected pixel. We compare the uniformly-random and localized random sampling methods over a large space of sampling parameters, and show that, for the optimal parameter choices, higher quality image reconstructions can be consistently obtained by using localized random sampling. In addition, we argue that the localized random CS optimal parameter choice is stable with respect to diverse natural images, and scales with the number of samples used for reconstruction. We expect that the localized random sampling protocol helps to explain the evolutionarily advantageous nature of receptive field structure in visual systems and suggests several future research areas in CS theory and its application to brain imaging. PMID:27555464

  16. Methodology Series Module 5: Sampling Strategies.

    PubMed

    Setia, Maninder Singh

    2016-01-01

    Once the research question and the research design have been finalised, it is important to select the appropriate sample for the study. The method by which the researcher selects the sample is the ' Sampling Method'. There are essentially two types of sampling methods: 1) probability sampling - based on chance events (such as random numbers, flipping a coin etc.); and 2) non-probability sampling - based on researcher's choice, population that accessible & available. Some of the non-probability sampling methods are: purposive sampling, convenience sampling, or quota sampling. Random sampling method (such as simple random sample or stratified random sample) is a form of probability sampling. It is important to understand the different sampling methods used in clinical studies and mention this method clearly in the manuscript. The researcher should not misrepresent the sampling method in the manuscript (such as using the term ' random sample' when the researcher has used convenience sample). The sampling method will depend on the research question. For instance, the researcher may want to understand an issue in greater detail for one particular population rather than worry about the ' generalizability' of these results. In such a scenario, the researcher may want to use ' purposive sampling' for the study.

  17. Methodology Series Module 5: Sampling Strategies

    PubMed Central

    Setia, Maninder Singh

    2016-01-01

    Once the research question and the research design have been finalised, it is important to select the appropriate sample for the study. The method by which the researcher selects the sample is the ‘ Sampling Method’. There are essentially two types of sampling methods: 1) probability sampling – based on chance events (such as random numbers, flipping a coin etc.); and 2) non-probability sampling – based on researcher's choice, population that accessible & available. Some of the non-probability sampling methods are: purposive sampling, convenience sampling, or quota sampling. Random sampling method (such as simple random sample or stratified random sample) is a form of probability sampling. It is important to understand the different sampling methods used in clinical studies and mention this method clearly in the manuscript. The researcher should not misrepresent the sampling method in the manuscript (such as using the term ‘ random sample’ when the researcher has used convenience sample). The sampling method will depend on the research question. For instance, the researcher may want to understand an issue in greater detail for one particular population rather than worry about the ‘ generalizability’ of these results. In such a scenario, the researcher may want to use ‘ purposive sampling’ for the study. PMID:27688438

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

    PubMed

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

    2016-11-17

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

  19. RBANS Norms based on the Relationship of Age, Gender, Education, and WRAT-3 Reading to Performance within an Older African American Sample.

    PubMed

    Andreotti, Charissa; Hawkins, Keith A

    2015-01-01

    Due to factors including differences in educational opportunity, African Americans and Caucasians frequently differ on cognitive tests creating diagnostic error risks. Such differences have been found on the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), and preliminary norms based on a small sample of African Americans have been generated. In a larger sample of community-dwelling older African Americans, we explored sources of variance including age, gender, common medical conditions, years of education, and reading level to generate norms stratified on the most relevant bases. Three hundred and fifty-five African Americans aged 55+ and living independently completed the RBANS and health, education, and psychosocial interviews. Hypertension and type 2 diabetes were unrelated to overall RBANS performance once age and education were accounted for. Age, education, and WRAT-3 Reading score (a proxy for scholastic attainment) were independent predictors of RBANS performance. Females performed better on List Learning, Story Memory, Fluency, Coding, List Recall, and List Recognition; males were superior on Line Orientation and Picture Naming. In addition to generating norms stratified by age, we provide descriptive statistics grouped by age and education, and by age and WRAT-3 Reading grade level, to provide clinicians with the opportunity to tailor their interpretation of scores based upon perceived best fit for their patient. Regression formulas are provided to address gender differences. To complement the standard index norms, we provide norms for alternative indexes representing additional an factor structure of cognitive domains.

  20. The relationships between sixteen perfluorinated compound concentrations in blood serum and food, and other parameters, in the general population of South Korea with proportionate stratified sampling method.

    PubMed

    Kim, Hee-Young; Kim, Seung-Kyu; Kang, Dong-Mug; Hwang, Yong-Sik; Oh, Jeong-Eun

    2014-02-01

    Serum samples were collected from volunteers of various ages and both genders using a proportionate stratified sampling method, to assess the exposure of the general population in Busan, South Korea to perfluorinated compounds (PFCs). 16 PFCs were investigated in serum samples from 306 adults (124 males and 182 females) and one day composite diet samples (breakfast, lunch, and dinner) from 20 of the serum donors, to investigate the relationship between food and serum PFC concentrations. Perfluorooctanoic acid and perfluorooctanesulfonic acid were the dominant PFCs in the serum samples, with mean concentrations of 8.4 and 13 ng/mL, respectively. Perfluorotridecanoic acid was the dominant PFC in the composite food samples, ranging from

    samples increased with the age of the volunteer, and were higher in males than in females, similar to the results of other studies. We confirmed from the relationships between questionnaire results and the PFC concentrations in the serum samples, that food is one of the important contribution factors of human exposure to PFCs. However, there were no correlations between the PFC concentrations in the one day composite diet samples and the serum samples, because a one day composite diet sample is not necessarily representative of a person's long-term diet and because of the small number of samples taken. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Spatial Sampling of Weather Data for Regional Crop Yield Simulations

    NASA Technical Reports Server (NTRS)

    Van Bussel, Lenny G. J.; Ewert, Frank; Zhao, Gang; Hoffmann, Holger; Enders, Andreas; Wallach, Daniel; Asseng, Senthold; Baigorria, Guillermo A.; Basso, Bruno; Biernath, Christian; hide

    2016-01-01

    Field-scale crop models are increasingly applied at spatio-temporal scales that range from regions to the globe and from decades up to 100 years. Sufficiently detailed data to capture the prevailing spatio-temporal heterogeneity in weather, soil, and management conditions as needed by crop models are rarely available. Effective sampling may overcome the problem of missing data but has rarely been investigated. In this study the effect of sampling weather data has been evaluated for simulating yields of winter wheat in a region in Germany over a 30-year period (1982-2011) using 12 process-based crop models. A stratified sampling was applied to compare the effect of different sizes of spatially sampled weather data (10, 30, 50, 100, 500, 1000 and full coverage of 34,078 sampling points) on simulated wheat yields. Stratified sampling was further compared with random sampling. Possible interactions between sample size and crop model were evaluated. The results showed differences in simulated yields among crop models but all models reproduced well the pattern of the stratification. Importantly, the regional mean of simulated yields based on full coverage could already be reproduced by a small sample of 10 points. This was also true for reproducing the temporal variability in simulated yields but more sampling points (about 100) were required to accurately reproduce spatial yield variability. The number of sampling points can be smaller when a stratified sampling is applied as compared to a random sampling. However, differences between crop models were observed including some interaction between the effect of sampling on simulated yields and the model used. We concluded that stratified sampling can considerably reduce the number of required simulations. But, differences between crop models must be considered as the choice for a specific model can have larger effects on simulated yields than the sampling strategy. Assessing the impact of sampling soil and crop management

  2. A comparison of two sampling designs for fish assemblage assessment in a large river

    USGS Publications Warehouse

    Kiraly, Ian A.; Coghlan, Stephen M.; Zydlewski, Joseph D.; Hayes, Daniel

    2014-01-01

    We compared the efficiency of stratified random and fixed-station sampling designs to characterize fish assemblages in anticipation of dam removal on the Penobscot River, the largest river in Maine. We used boat electrofishing methods in both sampling designs. Multiple 500-m transects were selected randomly and electrofished in each of nine strata within the stratified random sampling design. Within the fixed-station design, up to 11 transects (1,000 m) were electrofished, all of which had been sampled previously. In total, 88 km of shoreline were electrofished during summer and fall in 2010 and 2011, and 45,874 individuals of 34 fish species were captured. Species-accumulation and dissimilarity curve analyses indicated that all sampling effort, other than fall 2011 under the fixed-station design, provided repeatable estimates of total species richness and proportional abundances. Overall, our sampling designs were similar in precision and efficiency for sampling fish assemblages. The fixed-station design was negatively biased for estimating the abundance of species such as Common Shiner Luxilus cornutus and Fallfish Semotilus corporalis and was positively biased for estimating biomass for species such as White Sucker Catostomus commersonii and Atlantic Salmon Salmo salar. However, we found no significant differences between the designs for proportional catch and biomass per unit effort, except in fall 2011. The difference observed in fall 2011 was due to limitations on the number and location of fixed sites that could be sampled, rather than an inherent bias within the design. Given the results from sampling in the Penobscot River, application of the stratified random design is preferable to the fixed-station design due to less potential for bias caused by varying sampling effort, such as what occurred in the fall 2011 fixed-station sample or due to purposeful site selection.

  3. Sampling large random knots in a confined space

    NASA Astrophysics Data System (ADS)

    Arsuaga, J.; Blackstone, T.; Diao, Y.; Hinson, K.; Karadayi, E.; Saito, M.

    2007-09-01

    DNA knots formed under extreme conditions of condensation, as in bacteriophage P4, are difficult to analyze experimentally and theoretically. In this paper, we propose to use the uniform random polygon model as a supplementary method to the existing methods for generating random knots in confinement. The uniform random polygon model allows us to sample knots with large crossing numbers and also to generate large diagrammatically prime knot diagrams. We show numerically that uniform random polygons sample knots with large minimum crossing numbers and certain complicated knot invariants (as those observed experimentally). We do this in terms of the knot determinants or colorings. Our numerical results suggest that the average determinant of a uniform random polygon of n vertices grows faster than O(e^{n^2}) . We also investigate the complexity of prime knot diagrams. We show rigorously that the probability that a randomly selected 2D uniform random polygon of n vertices is almost diagrammatically prime goes to 1 as n goes to infinity. Furthermore, the average number of crossings in such a diagram is at the order of O(n2). Therefore, the two-dimensional uniform random polygons offer an effective way in sampling large (prime) knots, which can be useful in various applications.

  4. A Dexterous Optional Randomized Response Model

    ERIC Educational Resources Information Center

    Tarray, Tanveer A.; Singh, Housila P.; Yan, Zaizai

    2017-01-01

    This article addresses the problem of estimating the proportion Pi[subscript S] of the population belonging to a sensitive group using optional randomized response technique in stratified sampling based on Mangat model that has proportional and Neyman allocation and larger gain in efficiency. Numerically, it is found that the suggested model is…

  5. Helicity dynamics in stratified turbulence in the absence of forcing.

    PubMed

    Rorai, C; Rosenberg, D; Pouquet, A; Mininni, P D

    2013-06-01

    A numerical study of decaying stably stratified flows is performed. Relatively high stratification (Froude number ≈10(-2)-10(-1)) and moderate Reynolds (Re) numbers (Re≈ 3-6×10(3)) are considered and a particular emphasis is placed on the role of helicity (velocity-vorticity correlations), which is not an invariant of the nondissipative equations. The problem is tackled by integrating the Boussinesq equations in a periodic cubical domain using different initial conditions: a nonhelical Taylor-Green (TG) flow, a fully helical Beltrami [Arnold-Beltrami-Childress (ABC)] flow, and random flows with a tunable helicity. We show that for stratified ABC flows helicity undergoes a substantially slower decay than for unstratified ABC flows. This fact is likely associated to the combined effect of stratification and large-scale coherent structures. Indeed, when the latter are missing, as in random flows, helicity is rapidly destroyed by the onset of gravitational waves. A type of large-scale dissipative "cyclostrophic" balance can be invoked to explain this behavior. No production of helicity is observed, contrary to the case of rotating and stratified flows. When helicity survives in the system, it strongly affects the temporal energy decay and the energy distribution among Fourier modes. We discover in fact that the decay rate of energy for stratified helical flows is much slower than for stratified nonhelical flows and can be considered with a phenomenological model in a way similar to what is done for unstratified rotating flows. We also show that helicity, when strong, has a measurable effect on the Fourier spectra, in particular at scales larger than the buoyancy scale, for which it displays a rather flat scaling associated with vertical shear, as observed in the planetary boundary layer.

  6. Efficacy and Safety of Vedolizumab in Ulcerative Colitis and Crohn's Disease Patients Stratified by Age.

    PubMed

    Yajnik, Vijay; Khan, Nabeel; Dubinsky, Marla; Axler, Jeffrey; James, Alexandra; Abhyankar, Brihad; Lasch, Karen

    2017-02-01

    The efficacy and safety of vedolizumab, a gut-selective α 4 β 7 integrin antibody, were demonstrated in the GEMINI 1 and GEMINI 2 clinical trials of adults aged 18-80 years. We investigated the efficacy and safety of vedolizumab in patients stratified by age from the GEMINI trials. Safety and efficacy, including clinical response, clinical remission, and corticosteroid-free remission, at week 6 and/or 52 were determined post hoc in patients aged <35, 35 to <55, and ≥55 years. At baseline, 353, 412, and 130 ulcerative colitis (UC) and 582, 443, and 90 Crohn's disease (CD) patients were aged <35, 35 to <55, and ≥55. Of these patients, 56 were aged ≥65 years (UC: 33, CD: 23). Trends favoring vedolizumab over placebo were observed for most efficacy endpoints irrespective of patient age; some variability between subgroups was observed. Safety profiles of vedolizumab and placebo were similar in all age groups. Vedolizumab-treated patients aged ≥55 had the lowest incidence of serious infections (0.9 per 100 person-years) and adverse events leading to hospitalization (14.8 per 100 person-years). There were no age-related differences in the incidence of adverse hematological events, malignancy, or death. The safety and efficacy of vedolizumab in patients with UC or CD were similar for all age groups. The number of patients in the oldest age group in these analyses was small; thus further studies of vedolizumab in larger cohorts of elderly patients are warranted. Millennium Pharmaceuticals, Inc. (d/b/a Takeda Pharmaceuticals International Co.).

  7. Accuracy assessment, using stratified plurality sampling, of portions of a LANDSAT classification of the Arctic National Wildlife Refuge Coastal Plain

    NASA Technical Reports Server (NTRS)

    Card, Don H.; Strong, Laurence L.

    1989-01-01

    An application of a classification accuracy assessment procedure is described for a vegetation and land cover map prepared by digital image processing of LANDSAT multispectral scanner data. A statistical sampling procedure called Stratified Plurality Sampling was used to assess the accuracy of portions of a map of the Arctic National Wildlife Refuge coastal plain. Results are tabulated as percent correct classification overall as well as per category with associated confidence intervals. Although values of percent correct were disappointingly low for most categories, the study was useful in highlighting sources of classification error and demonstrating shortcomings of the plurality sampling method.

  8. Random vs. systematic sampling from administrative databases involving human subjects.

    PubMed

    Hagino, C; Lo, R J

    1998-09-01

    Two sampling techniques, simple random sampling (SRS) and systematic sampling (SS), were compared to determine whether they yield similar and accurate distributions for the following four factors: age, gender, geographic location and years in practice. Any point estimate within 7 yr or 7 percentage points of its reference standard (SRS or the entire data set, i.e., the target population) was considered "acceptably similar" to the reference standard. The sampling frame was from the entire membership database of the Canadian Chiropractic Association. The two sampling methods were tested using eight different sample sizes of n (50, 100, 150, 200, 250, 300, 500, 800). From the profile/characteristics, summaries of four known factors [gender, average age, number (%) of chiropractors in each province and years in practice], between- and within-methods chi 2 tests and unpaired t tests were performed to determine whether any of the differences [descriptively greater than 7% or 7 yr] were also statistically significant. The strengths of the agreements between the provincial distributions were quantified by calculating the percent agreements for each (provincial pairwise-comparison methods). Any percent agreement less than 70% was judged to be unacceptable. Our assessments of the two sampling methods (SRS and SS) for the different sample sizes tested suggest that SRS and SS yielded acceptably similar results. Both methods started to yield "correct" sample profiles at approximately the same sample size (n > 200). SS is not only convenient, it can be recommended for sampling from large databases in which the data are listed without any inherent order biases other than alphabetical listing by surname.

  9. Repeated Random Sampling in Year 5

    ERIC Educational Resources Information Center

    Watson, Jane M.; English, Lyn D.

    2016-01-01

    As an extension to an activity introducing Year 5 students to the practice of statistics, the software "TinkerPlots" made it possible to collect repeated random samples from a finite population to informally explore students' capacity to begin reasoning with a distribution of sample statistics. This article provides background for the…

  10. A Matter of Classes: Stratifying Health Care Populations to Produce Better Estimates of Inpatient Costs

    PubMed Central

    Rein, David B

    2005-01-01

    Objective To stratify traditional risk-adjustment models by health severity classes in a way that is empirically based, is accessible to policy makers, and improves predictions of inpatient costs. Data Sources Secondary data created from the administrative claims from all 829,356 children aged 21 years and under enrolled in Georgia Medicaid in 1999. Study Design A finite mixture model was used to assign child Medicaid patients to health severity classes. These class assignments were then used to stratify both portions of a traditional two-part risk-adjustment model predicting inpatient Medicaid expenditures. Traditional model results were compared with the stratified model using actuarial statistics. Principal Findings The finite mixture model identified four classes of children: a majority healthy class and three illness classes with increasing levels of severity. Stratifying the traditional two-part risk-adjustment model by health severity classes improved its R2 from 0.17 to 0.25. The majority of additional predictive power resulted from stratifying the second part of the two-part model. Further, the preference for the stratified model was unaffected by months of patient enrollment time. Conclusions Stratifying health care populations based on measures of health severity is a powerful method to achieve more accurate cost predictions. Insurers who ignore the predictive advances of sample stratification in setting risk-adjusted premiums may create strong financial incentives for adverse selection. Finite mixture models provide an empirically based, replicable methodology for stratification that should be accessible to most health care financial managers. PMID:16033501

  11. Methods for sample size determination in cluster randomized trials

    PubMed Central

    Rutterford, Clare; Copas, Andrew; Eldridge, Sandra

    2015-01-01

    Background: The use of cluster randomized trials (CRTs) is increasing, along with the variety in their design and analysis. The simplest approach for their sample size calculation is to calculate the sample size assuming individual randomization and inflate this by a design effect to account for randomization by cluster. The assumptions of a simple design effect may not always be met; alternative or more complicated approaches are required. Methods: We summarise a wide range of sample size methods available for cluster randomized trials. For those familiar with sample size calculations for individually randomized trials but with less experience in the clustered case, this manuscript provides formulae for a wide range of scenarios with associated explanation and recommendations. For those with more experience, comprehensive summaries are provided that allow quick identification of methods for a given design, outcome and analysis method. Results: We present first those methods applicable to the simplest two-arm, parallel group, completely randomized design followed by methods that incorporate deviations from this design such as: variability in cluster sizes; attrition; non-compliance; or the inclusion of baseline covariates or repeated measures. The paper concludes with methods for alternative designs. Conclusions: There is a large amount of methodology available for sample size calculations in CRTs. This paper gives the most comprehensive description of published methodology for sample size calculation and provides an important resource for those designing these trials. PMID:26174515

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

    NASA Astrophysics Data System (ADS)

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

    2018-02-01

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

  13. [Stratified sampling survey of major human parasitic diseases in Henan province].

    PubMed

    Xu, B L; Zhang, H W; Deng, Y; Chen, Z L; Chen, W Q; Lu, D L; Zhang, Y L; Zhao, Y L; Lin, X M; Huang, Q; Yang, C Y; Liu, Y; Zhou, R M; Li, P; Chen, J S; He, L J; Qian, D

    2018-03-10

    Objective: To understand the prevalence of major human parasitic diseases and related factors in Henan province. Methods: This stratified sampling survey was carried out according to the requirement of national survey protocol of major human parasitic diseases, 2014-2015. The prevalence of soil-transmitted helminths infection, taeniasis and intestinal protozoiasis were surveyed in 104 sites selected from 35 counties (districts) and the prevalence of clonorchiasis was surveyed in 62 sites selected from 37 townships. In each survey spot, 250 persons were surveyed. A total of 26 866 persons and 15 893 persons were surveyed. Modified Kato-Katz thick smear was used to detect the eggs of intestinal helminthes. Tube fecal culture was used to identify the species of hookworm. The Enterobius eggs were detected in children aged 3 to 6 years by using adhesive tape. The cyst and trophozoite of intestinal protozoa were examined with physiological saline direct smear method and iodine stain method. Results: The overall infestation rate of intestinal parasites was2.02% in Henan, and the worm infection rate was higher than protozoa infection rate. Fourteen kinds of intestinal parasites were found, including nematode (5 species), trematode (2 species), and protozoan (7 species). The infection rate of Enterobius vermicularis was highest, and Qinba Mountain ecological area had the highest infestation rate of intestinal parasites in 4 ecological areas of Henan. There was no significant difference in intestinal parasite infection rate between males and females ( χ (2)=3.630, P =0.057), and the differences in intestinal parasite infection rate among different age groups had significance ( χ (2)=124.783, P =0.000 1). The infection rate reached the peak in age group ≤9 years and the major parasite was Enterobius vermicularis . Furthermore the overall human infection rate of parasite showed a downward trend with the increase of educational level of the people ( χ (2)=70.969, P =0

  14. RandomSpot: A web-based tool for systematic random sampling of virtual slides.

    PubMed

    Wright, Alexander I; Grabsch, Heike I; Treanor, Darren E

    2015-01-01

    This paper describes work presented at the Nordic Symposium on Digital Pathology 2014, Linköping, Sweden. Systematic random sampling (SRS) is a stereological tool, which provides a framework to quickly build an accurate estimation of the distribution of objects or classes within an image, whilst minimizing the number of observations required. RandomSpot is a web-based tool for SRS in stereology, which systematically places equidistant points within a given region of interest on a virtual slide. Each point can then be visually inspected by a pathologist in order to generate an unbiased sample of the distribution of classes within the tissue. Further measurements can then be derived from the distribution, such as the ratio of tumor to stroma. RandomSpot replicates the fundamental principle of traditional light microscope grid-shaped graticules, with the added benefits associated with virtual slides, such as facilitated collaboration and automated navigation between points. Once the sample points have been added to the region(s) of interest, users can download the annotations and view them locally using their virtual slide viewing software. Since its introduction, RandomSpot has been used extensively for international collaborative projects, clinical trials and independent research projects. So far, the system has been used to generate over 21,000 sample sets, and has been used to generate data for use in multiple publications, identifying significant new prognostic markers in colorectal, upper gastro-intestinal and breast cancer. Data generated using RandomSpot also has significant value for training image analysis algorithms using sample point coordinates and pathologist classifications.

  15. An Efficient Alternative Mixed Randomized Response Procedure

    ERIC Educational Resources Information Center

    Singh, Housila P.; Tarray, Tanveer A.

    2015-01-01

    In this article, we have suggested a new modified mixed randomized response (RR) model and studied its properties. It is shown that the proposed mixed RR model is always more efficient than the Kim and Warde's mixed RR model. The proposed mixed RR model has also been extended to stratified sampling. Numerical illustrations and graphical…

  16. Gender differences in the age-stratified prevalence of risk factors in Korean ischemic stroke patients: a nationwide stroke registry-based cross-sectional study.

    PubMed

    Park, Tai Hwan; Ko, Youngchai; Lee, Soo Joo; Lee, Kyung Bok; Lee, Jun; Han, Moon-Ku; Park, Jong-Moo; Kim, Dong-Eog; Cho, Yong-Jin; Hong, Keun-Sik; Kim, Joon-Tae; Cho, Ki-Hyun; Kim, Dae-Hyun; Cha, Jae-Kwan; Yu, Kyung-Ho; Lee, Byung-Chul; Yoon, Byung-Woo; Lee, Ji Sung; Lee, Juneyoung; Gorelick, Philip B; Bae, Hee-Joon

    2014-08-01

    Although ethnic or cultural differences affect prevalence of cardiovascular risk factors, limited information is available about the age- and gender-stratified prevalence of the risk factors in Asian stroke population. We assessed gender- and age-stratified prevalences of major risk factors in Korean stroke patients, and assumed that the gender differences are attenuated by adjustment with lifestyle factors. Using the nationwide hospital-based stroke registry, we identified 9417 ischemic stroke patients admitted between April 2008 and January 2011. Prevalence of hypertension, diabetes, hyperlipidemia, atrial fibrillation, prior stroke, and coronary heart disease was assessed in both genders by age groups. We analyzed gender differences of the prevalence among the age groups by calculating prevalence ratio, and further explored the influence of lifestyle factors on the gender difference in multivariable analyses. Hypertension and hyperlipidemia were more common in men until middle age, but after that more common in women, whereas diabetes was more common in women after 65 years of age. Atrial fibrillation increased steadily with age in both genders but was more common in women through all age groups. Prior stroke and coronary heart disease showed inconsistent gender differences. Gender differences in hypertension and diabetes among the age groups were attenuated by adjustment with accompanying risk factors including lifestyle factors. Korean women with stroke had more hypertension and hyperlipidemia after middle age, more diabetes after 65 years, and more atrial fibrillation throughout all ages. Strategies to control risk factors in women at risk for stroke are eagerly needed. © 2013 The Authors. International Journal of Stroke © 2013 World Stroke Organization.

  17. Ages of Records in Random Walks

    NASA Astrophysics Data System (ADS)

    Szabó, Réka; Vető, Bálint

    2016-12-01

    We consider random walks with continuous and symmetric step distributions. We prove universal asymptotics for the average proportion of the age of the kth longest lasting record for k=1,2,ldots and for the probability that the record of the kth longest age is broken at step n. Due to the relation to the Chinese restaurant process, the ranked sequence of proportions of ages converges to the Poisson-Dirichlet distribution.

  18. Development of a sampling strategy and sample size calculation to estimate the distribution of mammographic breast density in Korean women.

    PubMed

    Jun, Jae Kwan; Kim, Mi Jin; Choi, Kui Son; Suh, Mina; Jung, Kyu-Won

    2012-01-01

    Mammographic breast density is a known risk factor for breast cancer. To conduct a survey to estimate the distribution of mammographic breast density in Korean women, appropriate sampling strategies for representative and efficient sampling design were evaluated through simulation. Using the target population from the National Cancer Screening Programme (NCSP) for breast cancer in 2009, we verified the distribution estimate by repeating the simulation 1,000 times using stratified random sampling to investigate the distribution of breast density of 1,340,362 women. According to the simulation results, using a sampling design stratifying the nation into three groups (metropolitan, urban, and rural), with a total sample size of 4,000, we estimated the distribution of breast density in Korean women at a level of 0.01% tolerance. Based on the results of our study, a nationwide survey for estimating the distribution of mammographic breast density among Korean women can be conducted efficiently.

  19. Sequential time interleaved random equivalent sampling for repetitive signal.

    PubMed

    Zhao, Yijiu; Liu, Jingjing

    2016-12-01

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

  20. A nonparametric method to generate synthetic populations to adjust for complex sampling design features.

    PubMed

    Dong, Qi; Elliott, Michael R; Raghunathan, Trivellore E

    2014-06-01

    Outside of the survey sampling literature, samples are often assumed to be generated by a simple random sampling process that produces independent and identically distributed (IID) samples. Many statistical methods are developed largely in this IID world. Application of these methods to data from complex sample surveys without making allowance for the survey design features can lead to erroneous inferences. Hence, much time and effort have been devoted to develop the statistical methods to analyze complex survey data and account for the sample design. This issue is particularly important when generating synthetic populations using finite population Bayesian inference, as is often done in missing data or disclosure risk settings, or when combining data from multiple surveys. By extending previous work in finite population Bayesian bootstrap literature, we propose a method to generate synthetic populations from a posterior predictive distribution in a fashion inverts the complex sampling design features and generates simple random samples from a superpopulation point of view, making adjustment on the complex data so that they can be analyzed as simple random samples. We consider a simulation study with a stratified, clustered unequal-probability of selection sample design, and use the proposed nonparametric method to generate synthetic populations for the 2006 National Health Interview Survey (NHIS), and the Medical Expenditure Panel Survey (MEPS), which are stratified, clustered unequal-probability of selection sample designs.

  1. A nonparametric method to generate synthetic populations to adjust for complex sampling design features

    PubMed Central

    Dong, Qi; Elliott, Michael R.; Raghunathan, Trivellore E.

    2017-01-01

    Outside of the survey sampling literature, samples are often assumed to be generated by a simple random sampling process that produces independent and identically distributed (IID) samples. Many statistical methods are developed largely in this IID world. Application of these methods to data from complex sample surveys without making allowance for the survey design features can lead to erroneous inferences. Hence, much time and effort have been devoted to develop the statistical methods to analyze complex survey data and account for the sample design. This issue is particularly important when generating synthetic populations using finite population Bayesian inference, as is often done in missing data or disclosure risk settings, or when combining data from multiple surveys. By extending previous work in finite population Bayesian bootstrap literature, we propose a method to generate synthetic populations from a posterior predictive distribution in a fashion inverts the complex sampling design features and generates simple random samples from a superpopulation point of view, making adjustment on the complex data so that they can be analyzed as simple random samples. We consider a simulation study with a stratified, clustered unequal-probability of selection sample design, and use the proposed nonparametric method to generate synthetic populations for the 2006 National Health Interview Survey (NHIS), and the Medical Expenditure Panel Survey (MEPS), which are stratified, clustered unequal-probability of selection sample designs. PMID:29200608

  2. Quantifying errors without random sampling.

    PubMed

    Phillips, Carl V; LaPole, Luwanna M

    2003-06-12

    All quantifications of mortality, morbidity, and other health measures involve numerous sources of error. The routine quantification of random sampling error makes it easy to forget that other sources of error can and should be quantified. When a quantification does not involve sampling, error is almost never quantified and results are often reported in ways that dramatically overstate their precision. We argue that the precision implicit in typical reporting is problematic and sketch methods for quantifying the various sources of error, building up from simple examples that can be solved analytically to more complex cases. There are straightforward ways to partially quantify the uncertainty surrounding a parameter that is not characterized by random sampling, such as limiting reported significant figures. We present simple methods for doing such quantifications, and for incorporating them into calculations. More complicated methods become necessary when multiple sources of uncertainty must be combined. We demonstrate that Monte Carlo simulation, using available software, can estimate the uncertainty resulting from complicated calculations with many sources of uncertainty. We apply the method to the current estimate of the annual incidence of foodborne illness in the United States. Quantifying uncertainty from systematic errors is practical. Reporting this uncertainty would more honestly represent study results, help show the probability that estimated values fall within some critical range, and facilitate better targeting of further research.

  3. Detection and monitoring of invasive exotic plants: a comparison of four sampling methods

    Treesearch

    Cynthia D. Huebner

    2007-01-01

    The ability to detect and monitor exotic invasive plants is likely to vary depending on the sampling method employed. Methods with strong qualitative thoroughness for species detection often lack the intensity necessary to monitor vegetation change. Four sampling methods (systematic plot, stratified-random plot, modified Whittaker, and timed meander) in hemlock and red...

  4. Performance of Stratified and Subgrouped Disproportionality Analyses in Spontaneous Databases.

    PubMed

    Seabroke, Suzie; Candore, Gianmario; Juhlin, Kristina; Quarcoo, Naashika; Wisniewski, Antoni; Arani, Ramin; Painter, Jeffery; Tregunno, Philip; Norén, G Niklas; Slattery, Jim

    2016-04-01

    Disproportionality analyses are used in many organisations to identify adverse drug reactions (ADRs) from spontaneous report data. Reporting patterns vary over time, with patient demographics, and between different geographical regions, and therefore subgroup analyses or adjustment by stratification may be beneficial. The objective of this study was to evaluate the performance of subgroup and stratified disproportionality analyses for a number of key covariates within spontaneous report databases of differing sizes and characteristics. Using a reference set of established ADRs, signal detection performance (sensitivity and precision) was compared for stratified, subgroup and crude (unadjusted) analyses within five spontaneous report databases (two company, one national and two international databases). Analyses were repeated for a range of covariates: age, sex, country/region of origin, calendar time period, event seriousness, vaccine/non-vaccine, reporter qualification and report source. Subgroup analyses consistently performed better than stratified analyses in all databases. Subgroup analyses also showed benefits in both sensitivity and precision over crude analyses for the larger international databases, whilst for the smaller databases a gain in precision tended to result in some loss of sensitivity. Additionally, stratified analyses did not increase sensitivity or precision beyond that associated with analytical artefacts of the analysis. The most promising subgroup covariates were age and region/country of origin, although this varied between databases. Subgroup analyses perform better than stratified analyses and should be considered over the latter in routine first-pass signal detection. Subgroup analyses are also clearly beneficial over crude analyses for larger databases, but further validation is required for smaller databases.

  5. Remote Sensing, Sampling and Simulation Applications in Analyses of Insect Dispersion and Abundance in Cotton

    Treesearch

    J. L. Willers; J. M. McKinion; J. N. Jenkins

    2006-01-01

    Simulation was employed to create stratified simple random samples of different sample unit sizes to represent tarnished plant bug abundance at different densities within various habitats of simulated cotton fields. These samples were used to investigate dispersion patterns of this cotton insect. It was found that the assessment of spatial pattern varied as a function...

  6. Electromagnetic Scattering by Fully Ordered and Quasi-Random Rigid Particulate Samples

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Dlugach, Janna M.; Mackowski, Daniel W.

    2016-01-01

    In this paper we have analyzed circumstances under which a rigid particulate sample can behave optically as a true discrete random medium consisting of particles randomly moving relative to each other during measurement. To this end, we applied the numerically exact superposition T-matrix method to model far-field scattering characteristics of fully ordered and quasi-randomly arranged rigid multiparticle groups in fixed and random orientations. We have shown that, in and of itself, averaging optical observables over movements of a rigid sample as a whole is insufficient unless it is combined with a quasi-random arrangement of the constituent particles in the sample. Otherwise, certain scattering effects typical of discrete random media (including some manifestations of coherent backscattering) may not be accurately replicated.

  7. SAS procedures for designing and analyzing sample surveys

    USGS Publications Warehouse

    Stafford, Joshua D.; Reinecke, Kenneth J.; Kaminski, Richard M.

    2003-01-01

    Complex surveys often are necessary to estimate occurrence (or distribution), density, and abundance of plants and animals for purposes of re-search and conservation. Most scientists are familiar with simple random sampling, where sample units are selected from a population of interest (sampling frame) with equal probability. However, the goal of ecological surveys often is to make inferences about populations over large or complex spatial areas where organisms are not homogeneously distributed or sampling frames are in-convenient or impossible to construct. Candidate sampling strategies for such complex surveys include stratified,multistage, and adaptive sampling (Thompson 1992, Buckland 1994).

  8. Nonuniform sampling theorems for random signals in the linear canonical transform domain

    NASA Astrophysics Data System (ADS)

    Shuiqing, Xu; Congmei, Jiang; Yi, Chai; Youqiang, Hu; Lei, Huang

    2018-06-01

    Nonuniform sampling can be encountered in various practical processes because of random events or poor timebase. The analysis and applications of the nonuniform sampling for deterministic signals related to the linear canonical transform (LCT) have been well considered and researched, but up to now no papers have been published regarding the various nonuniform sampling theorems for random signals related to the LCT. The aim of this article is to explore the nonuniform sampling and reconstruction of random signals associated with the LCT. First, some special nonuniform sampling models are briefly introduced. Second, based on these models, some reconstruction theorems for random signals from various nonuniform samples associated with the LCT have been derived. Finally, the simulation results are made to prove the accuracy of the sampling theorems. In addition, the latent real practices of the nonuniform sampling for random signals have been also discussed.

  9. Reductions of intimate partner violence resulting from supplementing children with omega-3 fatty acids: A randomized, double-blind, placebo-controlled, stratified, parallel-group trial.

    PubMed

    Portnoy, Jill; Raine, Adrian; Liu, Jianghong; Hibbeln, Joseph R

    2018-05-20

    Omega-3 supplementation has been found to reduce externalizing behavior in children. Reciprocal models of parent-child behavior suggest that improving child behavior could lead to improvements in parent behavior, however no study has examined whether omega-3 supplementation in children could reduce intimate partner violence or child maltreatment by their adult caregivers. In this randomized, double-blind, placebo-controlled, stratified, parallel group trial, a community sample of children were randomized to receive either a fruit drink containing 1 gm of omega-3 fats (Smartfish Recharge; Omega-3 group, n = 100) or the same fruit drink without omega-3's (Placebo group, n = 100). Child participants, adult caregivers, and research staff were blinded to group assignment. Adult caregivers reported inter-partner and child-directed physical assault and psychological aggression at baseline, 6 months (end of treatment) and 12 months (6 months post-treatment) using the Conflicts Tactics Scale. Caregivers of children in the omega-3 group reported long-term reductions in psychological aggression in a group × time interaction. Improvements in adult psychological aggression were correlated with improvements in child externalizing behavior scores. No differences were reported for child maltreatment. This study is the first to show that omega-3 supplementation in children can reduce inter-partner psychological aggression among adult caregivers not receiving supplements. Findings suggest that improving child behavior through omega-3 supplementation could have long-term benefits to the family system as a whole. © 2018 Wiley Periodicals, Inc.

  10. Association of Mismatch Repair Mutation With Age at Cancer Onset in Lynch Syndrome: Implications for Stratified Surveillance Strategies.

    PubMed

    Ryan, Neil A J; Morris, Julie; Green, Kate; Lalloo, Fiona; Woodward, Emma R; Hill, James; Crosbie, Emma J; Evans, D Gareth

    2017-12-01

    Lynch syndrome is caused by dominantly inherited germline mutations that predispose individuals to colorectal, endometrial, ovarian, and other cancers through inactivation of the cellular mismatch repair system. Lynch syndrome–associated cancers are amenable to surveillance strategies that may improve survival. The age at which surveillance should start is disputed. To determine whether mutated gene and type of mutation influence age at onset of Lynch syndrome–associated cancers. A retrospective cohort study of individuals with Lynch syndrome–associated colorectal, endometrial, and/or ovarian cancers whose medical records were included in the clinical database of a large quaternary referral center for genomic medicine in the Northwest of England. Mutated gene (MLH1, MSH2, MSH6, and/or PMS2) and type of mutation (truncating, splicing, or large rearrangement). Age at cancer diagnosis. A total of 1063 individuals with proven Lynch syndrome were included, 495 male and 568 female (mean age 52 years; age range, 10-93 years [children were included in the database, but no children developed cancer]). There were 546 men and women with colorectal cancer, 162 women with endometrial cancer, and 49 women with ovarian cancer; mean follow-up was 68.2 months. Among MLH1 mutation carriers, mutations in MLH1 were associated with colorectal cancer in 249 (61%) of 409 men and women; endometrial cancer in 53 of 196 (27%) women; and ovarian cancer in 15 (8%) of 196 women. Among MSH2 mutation carriers, mutations in MSH2 (the most prevalent mutations overall) were most commonly associated with female-specific cancers: endometrial cancer in 83 (30%) of 279 women; ovarian cancer in 28 (10%) of 279 women; and colorectal cancer in 239 (50%) 479 men and women. Mutations in MSH6 were less prevalent, and MSH6 mutation carriers presented with colorectal and endometrial cancer at later ages than carriers of mutations in MSH2 or MLH1. When stratified by mutation type, women with truncating

  11. Toward cost-efficient sampling methods

    NASA Astrophysics Data System (ADS)

    Luo, Peng; Li, Yongli; Wu, Chong; Zhang, Guijie

    2015-09-01

    The sampling method has been paid much attention in the field of complex network in general and statistical physics in particular. This paper proposes two new sampling methods based on the idea that a small part of vertices with high node degree could possess the most structure information of a complex network. The two proposed sampling methods are efficient in sampling high degree nodes so that they would be useful even if the sampling rate is low, which means cost-efficient. The first new sampling method is developed on the basis of the widely used stratified random sampling (SRS) method and the second one improves the famous snowball sampling (SBS) method. In order to demonstrate the validity and accuracy of two new sampling methods, we compare them with the existing sampling methods in three commonly used simulation networks that are scale-free network, random network, small-world network, and also in two real networks. The experimental results illustrate that the two proposed sampling methods perform much better than the existing sampling methods in terms of achieving the true network structure characteristics reflected by clustering coefficient, Bonacich centrality and average path length, especially when the sampling rate is low.

  12. Spline methods for approximating quantile functions and generating random samples

    NASA Technical Reports Server (NTRS)

    Schiess, J. R.; Matthews, C. G.

    1985-01-01

    Two cubic spline formulations are presented for representing the quantile function (inverse cumulative distribution function) of a random sample of data. Both B-spline and rational spline approximations are compared with analytic representations of the quantile function. It is also shown how these representations can be used to generate random samples for use in simulation studies. Comparisons are made on samples generated from known distributions and a sample of experimental data. The spline representations are more accurate for multimodal and skewed samples and to require much less time to generate samples than the analytic representation.

  13. The relationship between blood viscosity and blood pressure in a random sample of the population aged 55 to 74 years.

    PubMed

    Fowkes, F G; Lowe, G D; Rumley, A; Lennie, S E; Smith, F B; Donnan, P T

    1993-05-01

    Blood viscosity is elevated in hypertensive subjects, but the association of viscosity with arterial blood pressure in the general population, and the influence of social, lifestyle and disease characteristics on this association, are not established. In the Edinburgh Artery Study, 1592 men and women aged 55-74 years selected randomly from the general population attended a university clinic. A fasting blood sample was taken for the measurement of blood viscosity and its major determinants (haematocrit, plasma viscosity and fibrinogen). Systolic pressure was related univariately to blood viscosity (P < 0.001), plasma viscosity (P < 0.001) and plasma fibrinogen (P < 0.01), but the association with fibrinogen did not persist after adjusting for body mass index. Diastolic pressure was related univariately to blood viscosity (P < 0.001) and plasma viscosity (P < 0.001) and haematocrit (P < 0.001) but not to fibrinogen. The only difference between the sexes was that the association between blood viscosity and systolic pressure was confined to males. Blood viscosity was associated equally with systolic and diastolic pressures in males, and remained independently related on multivariate analysis adjusting for age, sex, body mass index, social class, smoking, alcohol intake, exercise, angina, HDL and non-HDL cholesterol, diabetes mellitus, plasma viscosity, fibrinogen, and haematocrit.

  14. The Stroop Color-Word Test: Influence of Age, Sex, and Education; and Normative Data for a Large Sample Across the Adult Age Range

    ERIC Educational Resources Information Center

    Van der Elst, Wim; Van Boxtel, Martin P. J.; Van Breukelen, Gerard J. P.; Jolles, Jelle

    2006-01-01

    The Stroop Color-Word Test was administered to 1,856 cognitively screened, healthy Dutch-speaking participants aged 24 to 81 years. The effects of age, gender, and education on Stroop test performance were investigated to adequately stratify the normative data. The results showed that especially the speed-dependent Stroop scores (time to complete…

  15. Sleep Promotion Program for Improving Sleep Behaviors in Adolescents: A Randomized Controlled Pilot Study

    PubMed Central

    John, Bindu; Bellipady, Sumanth Shetty; Bhat, Shrinivasa Undaru

    2016-01-01

    Aims. The purpose of this pilot trial was to determine the efficacy of sleep promotion program to adapt it for the use of adolescents studying in various schools of Mangalore, India, and evaluate the feasibility issues before conducting a randomized controlled trial in a larger sample of adolescents. Methods. A randomized controlled trial design with stratified random sampling method was used. Fifty-eight adolescents were selected (mean age: 14.02 ± 2.15 years; intervention group, n = 34; control group, n = 24). Self-report questionnaires, including sociodemographic questionnaire with some additional questions on sleep and activities, Sleep Hygiene Index, Pittsburgh Sleep Quality Index, The Cleveland Adolescent Sleepiness Questionnaire, and PedsQL™ Present Functioning Visual Analogue Scale, were used. Results. Insufficient weekday-weekend sleep duration with increasing age of adolescents was observed. The program revealed a significant effect in the experimental group over the control group in overall sleep quality, sleep onset latency, sleep duration, daytime sleepiness, and emotional and overall distress. No significant effect was observed in sleep hygiene and other sleep parameters. All target variables showed significant correlations with each other. Conclusion. The intervention holds a promise for improving the sleep behaviors in healthy adolescents. However, the effect of the sleep promotion program treatment has yet to be proven through a future research. This trial is registered with ISRCTN13083118. PMID:27088040

  16. Adapted random sampling patterns for accelerated MRI.

    PubMed

    Knoll, Florian; Clason, Christian; Diwoky, Clemens; Stollberger, Rudolf

    2011-02-01

    Variable density random sampling patterns have recently become increasingly popular for accelerated imaging strategies, as they lead to incoherent aliasing artifacts. However, the design of these sampling patterns is still an open problem. Current strategies use model assumptions like polynomials of different order to generate a probability density function that is then used to generate the sampling pattern. This approach relies on the optimization of design parameters which is very time consuming and therefore impractical for daily clinical use. This work presents a new approach that generates sampling patterns by making use of power spectra of existing reference data sets and hence requires neither parameter tuning nor an a priori mathematical model of the density of sampling points. The approach is validated with downsampling experiments, as well as with accelerated in vivo measurements. The proposed approach is compared with established sampling patterns, and the generalization potential is tested by using a range of reference images. Quantitative evaluation is performed for the downsampling experiments using RMS differences to the original, fully sampled data set. Our results demonstrate that the image quality of the method presented in this paper is comparable to that of an established model-based strategy when optimization of the model parameter is carried out and yields superior results to non-optimized model parameters. However, no random sampling pattern showed superior performance when compared to conventional Cartesian subsampling for the considered reconstruction strategy.

  17. Mixing in a stratified shear flow: Energetics and sampling

    NASA Technical Reports Server (NTRS)

    Ivey, G. N.; Koseff, J. R.; Briggs, D. A.; Ferziger, J. H.

    1993-01-01

    Direct numerical simulations of the time evolution of homogeneous stably stratified shear flows have been performed for Richardson numbers from 0 to 1 and for Prandtl numbers between 0.1 and 2. The results indicate that mixing efficiency R(sub f) varies with turbulent Froude number in a manner consistent with laboratory experiments performed with Prandtl numbers of 0.7 and 700. However, unlike the laboratory results, for a particular Froude number, the simulations do not show a clear dependence on the magnitude of R(sub f) on Pr. The observed maximum value of R(sub f) is 0.25. When averaged over vertical length scales of an order of magnitude greater than either the overturning or Ozmidov scales of the flow, the simulations indicate that the dissipation rate epsilon is only weakly lognormally distributed with an intermittency of about 0.01 whereas estimated values in the ocean are 3 to 7.

  18. A Facility Specialist Model for Improving Retention of Nursing Home Staff: Results from a Randomized, Controlled Study

    ERIC Educational Resources Information Center

    Pillemer, Karl; Meador, Rhoda; Henderson, Charles, Jr.; Robison, Julie; Hegeman, Carol; Graham, Edwin; Schultz, Leslie

    2008-01-01

    Purpose: This article reports on a randomized, controlled intervention study designed to reduce employee turnover by creating a retention specialist position in nursing homes. Design and Methods: We collected data three times over a 1-year period in 30 nursing homes, sampled in stratified random manner from facilities in New York State and…

  19. Age-Stratified Treatment Response Rates in Hospitalized Patients with Clostridium difficile Infection Treated with Metronidazole

    PubMed Central

    Pham, Vy P.; Luce, Andrea M.; Ruppelt, Sara C.; Wei, Wenjing; Aitken, Samuel L.; Musick, William L.; Roux, Ryan K.

    2015-01-01

    Consensus on the optimal treatment of Clostridium difficile infection (CDI) is rapidly changing. Treatment with metronidazole has been associated with increased clinical failure rates; however, the reasons for this are unclear. The purpose of this study was to assess age-related treatment response rates in hospitalized patients with CDI treated with metronidazole. This was a retrospective, multicenter cohort study of hospitalized patients with CDI. Patients were assessed for refractory CDI, defined as persistent diarrhea after 7 days of metronidazole therapy, and stratified by age and clinical characteristics. A total of 242 individuals, aged 60 ± 18 years (Charlson comorbidity index, 3.8 ± 2.4; Horn's index, 1.7 ± 1.0) were included. One hundred twenty-eight patients (53%) had severe CDI. Seventy patients (29%) had refractory CDI, a percentage that increased from 22% to 28% and to 37% for patients aged less than 50 years, for patients from 50 to 70 years, and for patients aged >70 years, respectively (P = 0.05). In multivariate analysis, Horn's index (odds ratio [OR], 2.04; 95% confidence interval [CI], 1.50 to 2.77; P < 0.001), severe CDI (OR, 2.25; 95% CI, 1.15 to 4.41; P = 0.018), and continued use of antibiotics (OR, 2.65; 95% CI, 1.30 to 5.39; P = 0.0072) were identified as significant predictors of refractory CDI. Age was not identified as an independent risk factor for refractory CDI. Therefore, hospitalized elderly patients with CDI treated with metronidazole had increased refractory CDI rates likely due to increased underlying severity of illness, severity of CDI, and concomitant antibiotic use. These results may help identify patients that may benefit from alternative C. difficile treatments other than metronidazole. PMID:26195522

  20. Age-Stratified Treatment Response Rates in Hospitalized Patients with Clostridium difficile Infection Treated with Metronidazole.

    PubMed

    Pham, Vy P; Luce, Andrea M; Ruppelt, Sara C; Wei, Wenjing; Aitken, Samuel L; Musick, William L; Roux, Ryan K; Garey, Kevin W

    2015-10-01

    Consensus on the optimal treatment of Clostridium difficile infection (CDI) is rapidly changing. Treatment with metronidazole has been associated with increased clinical failure rates; however, the reasons for this are unclear. The purpose of this study was to assess age-related treatment response rates in hospitalized patients with CDI treated with metronidazole. This was a retrospective, multicenter cohort study of hospitalized patients with CDI. Patients were assessed for refractory CDI, defined as persistent diarrhea after 7 days of metronidazole therapy, and stratified by age and clinical characteristics. A total of 242 individuals, aged 60 ± 18 years (Charlson comorbidity index, 3.8 ± 2.4; Horn's index, 1.7 ± 1.0) were included. One hundred twenty-eight patients (53%) had severe CDI. Seventy patients (29%) had refractory CDI, a percentage that increased from 22% to 28% and to 37% for patients aged less than 50 years, for patients from 50 to 70 years, and for patients aged >70 years, respectively (P = 0.05). In multivariate analysis, Horn's index (odds ratio [OR], 2.04; 95% confidence interval [CI], 1.50 to 2.77; P < 0.001), severe CDI (OR, 2.25; 95% CI, 1.15 to 4.41; P = 0.018), and continued use of antibiotics (OR, 2.65; 95% CI, 1.30 to 5.39; P = 0.0072) were identified as significant predictors of refractory CDI. Age was not identified as an independent risk factor for refractory CDI. Therefore, hospitalized elderly patients with CDI treated with metronidazole had increased refractory CDI rates likely due to increased underlying severity of illness, severity of CDI, and concomitant antibiotic use. These results may help identify patients that may benefit from alternative C. difficile treatments other than metronidazole. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  1. Unmet demand for training among mature age Australians: Prevalence, differentials and perceived causes.

    PubMed

    Adair, Tim; Lourey, Emma; Taylor, Philip

    2016-03-01

    To explore the prevalence of unmet demand for training by mature age Australians and to identify the main barriers to accessing training. A total of 3007 Australians aged 45-74 years were surveyed using Computer Assisted Telephone Interviewing. The sample frame was randomly selected and stratified based on the capital city and the rest of the state, and data were weighted to be nationally representative. Over one-third (37%) of respondents who had worked in the past five years reported wanting to attend some form of training but were unable to; these were most likely women and those aged 45-54 year. Commonly cited reasons for not being able to attend training included not being able to fit it in with work commitments, affordability and employer reluctance. Reduction of these barriers to workplace training can improve mature age people's ability to remain engaged in the workforce. © 2015 AJA Inc.

  2. Patient volume, staffing, and workload in relation to risk-adjusted outcomes in a random stratified sample of UK neonatal intensive care units: a prospective evaluation.

    PubMed

    Tucker, Janet

    2002-01-12

    UK recommendations suggest that large neonatal intensive-care units (NICUs) have better outcomes than small units, although this suggestion remains unproven. We assessed whether patient volume, staffing levels, and workload are associated with risk-adjusted outcomes, and with costs or staff wellbeing. 186 UK NICUs were stratified according to volume of patients, nursing provision, and neonatal consultant provision. Primary outcomes were hospital mortality, mortality or cerebral damage, and nosocomial bacteraemia. We studied 13515 infants of all birthweights consecutively admitted to 54 randomly selected NICUs. Multiple logistic regression analyses were done with every primary outcome as the dependent variable. Staff wellbeing and stress were assessed by anonymous mental health index (MHI)-5 questionnaires. Data were available for 13334 (99%) infants. High-volume NICUs treated the sickest infants and had highest crude mortality. Risk-adjusted mortality and mortality or cerebral damage were unrelated to patient volume or staffing provision; however, nosocomial bacteraemia was less frequent in NICUs with low neonatal consultant provision (odds ratio 0.65, 95% CI 0.43-0.98). Mortality was raised with increasing workload in all types of NICUs. Infants admitted at full capacity versus half capacity were about 50% more likely to die, but there was wide uncertainty around this estimate. Most staff had MHI-5 scores that suggested good mental health. The implications of this report for staffing policy, medicolegal risk management, and ethical practice remain to be tested. Centralisation of only the sickest infants could improve efficiency, provided that this does not create excessive workload for staff. Assessment of increased staffing levels that are closer to those in adult intensive care might be appropriate.

  3. Sampling Methods in Cardiovascular Nursing Research: An Overview.

    PubMed

    Kandola, Damanpreet; Banner, Davina; O'Keefe-McCarthy, Sheila; Jassal, Debbie

    2014-01-01

    Cardiovascular nursing research covers a wide array of topics from health services to psychosocial patient experiences. The selection of specific participant samples is an important part of the research design and process. The sampling strategy employed is of utmost importance to ensure that a representative sample of participants is chosen. There are two main categories of sampling methods: probability and non-probability. Probability sampling is the random selection of elements from the population, where each element of the population has an equal and independent chance of being included in the sample. There are five main types of probability sampling including simple random sampling, systematic sampling, stratified sampling, cluster sampling, and multi-stage sampling. Non-probability sampling methods are those in which elements are chosen through non-random methods for inclusion into the research study and include convenience sampling, purposive sampling, and snowball sampling. Each approach offers distinct advantages and disadvantages and must be considered critically. In this research column, we provide an introduction to these key sampling techniques and draw on examples from the cardiovascular research. Understanding the differences in sampling techniques may aid nurses in effective appraisal of research literature and provide a reference pointfor nurses who engage in cardiovascular research.

  4. Application of Lamendin's adult dental aging technique to a diverse skeletal sample.

    PubMed

    Prince, Debra A; Ubelaker, Douglas H

    2002-01-01

    Lamendin et al. (1) proposed a technique to estimate age at death for adults by analyzing single-rooted teeth. They expressed age as a function of two factors: translucency of the tooth root and periodontosis (gingival regression). In their study, they analyzed 306 singled rooted teeth that were extracted at autopsy from 208 individuals of known age at death, all of whom were considered as having a French ancestry. Their sample consisted of 135 males, 73 females, 198 whites, and 10 blacks. The sample ranged in age from 22 to 90 years of age. By using a simple formulae (A = 0.18 x P + 0.42 x T + 25.53, where A = Age in years, P = Periodontosis height x 100/root height, and T = Transparency height x 100/root height), Lamendin et al. were able to estimate age at death with a mean error of +/- 10 years on their working sample and +/- 8.4 years on a forensic control sample. Lamendin found this technique to work well with a French population, but did not test it outside of that sample area. This study tests the accuracy of this adult aging technique on a more diverse skeletal population, the Terry Collection housed at the Smithsonian's National Museum of Natural History. Our sample consists of 400 teeth from 94 black females, 72 white females, 98 black males, and 95 white males, ranging from 25 to 99 years. Lamendin's technique was applied to this sample to test its applicability to a population not of French origin. Providing results from a diverse skeletal population will aid in establishing the validity of this method to be used in forensic cases, its ideal purpose. Our results suggest that Lamendin's method estimates age fairly accurately outside of the French sample yielding a mean error of 8.2 years, standard deviation 6.9 years, and standard error of the mean 0.34 years. In addition, when ancestry and sex are accounted for, the mean errors are reduced for each group (black females, white females, black males, and white males). Lamendin et al. reported an inter

  5. Using implicit association tests in age-heterogeneous samples: The importance of cognitive abilities and quad model processes.

    PubMed

    Wrzus, Cornelia; Egloff, Boris; Riediger, Michaela

    2017-08-01

    Implicit association tests (IATs) are increasingly used to indirectly assess people's traits, attitudes, or other characteristics. In addition to measuring traits or attitudes, IAT scores also reflect differences in cognitive abilities because scores are based on reaction times (RTs) and errors. As cognitive abilities change with age, questions arise concerning the usage and interpretation of IATs for people of different age. To address these questions, the current study examined how cognitive abilities and cognitive processes (i.e., quad model parameters) contribute to IAT results in a large age-heterogeneous sample. Participants (N = 549; 51% female) in an age-stratified sample (range = 12-88 years) completed different IATs and 2 tasks to assess cognitive processing speed and verbal ability. From the IAT data, D2-scores were computed based on RTs, and quad process parameters (activation of associations, overcoming bias, detection, guessing) were estimated from individual error rates. Substantial IAT scores and quad processes except guessing varied with age. Quad processes AC and D predicted D2-scores of the content-specific IAT. Importantly, the effects of cognitive abilities and quad processes on IAT scores were not significantly moderated by participants' age. These findings suggest that IATs seem suitable for age-heterogeneous studies from adolescence to old age when IATs are constructed and analyzed appropriately, for example with D-scores and process parameters. We offer further insight into how D-scoring controls for method effects in IATs and what IAT scores capture in addition to implicit representations of characteristics. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  6. Rationale and Design of Khuzestan Vitamin D Deficiency Screening Program in Pregnancy: A Stratified Randomized Vitamin D Supplementation Controlled Trial.

    PubMed

    Rostami, Maryam; Ramezani Tehrani, Fahimeh; Simbar, Masoumeh; Hosseinpanah, Farhad; Alavi Majd, Hamid

    2017-04-07

    Although there have been marked improvements in our understanding of vitamin D functions in different diseases, gaps on its role during pregnancy remain. Due to the lack of consensus on the most accurate marker of vitamin D deficiency during pregnancy and the optimal level of 25-hydroxyvitamin D, 25(OH)D, for its definition, vitamin D deficiency assessment during pregnancy is a complicated process. Besides, the optimal protocol for treatment of hypovitaminosis D and its effect on maternal and neonatal outcomes are still unclear. The aim of our study was to estimate the prevalence of vitamin D deficiency in the first trimester of pregnancy and to compare vitamin D screening strategy with no screening. Also, we intended to compare the effectiveness of various treatment regimens on maternal and neonatal outcomes in Masjed-Soleyman and Shushtar cities of Khuzestan province, Iran. This was a two-phase study. First, a population-based cross-sectional study was conducted; recruiting 1600 and 900 first trimester pregnant women from health centers of Masjed-Soleyman and Shushtar, respectively, using stratified multistage cluster sampling with probability proportional to size (PPS) method. Second, to assess the effect of screening strategy on maternal and neonatal outcomes, Masjed-Soleyman participants were assigned to a screening program versus Shushtar participants who became the nonscreening arm. Within the framework of the screening regimen, an 8-arm blind randomized clinical trial was undertaken to compare the effects of various treatment protocols. A total of 800 pregnant women with vitamin D deficiency were selected using simple random sampling from the 1600 individuals of Masjed-Soleyman as interventional groups. Serum concentrations of 25(OH)D were classified as: (1) severe deficient (<10ng/ml), (2) moderate deficient (10-20ng/ml), and (3) normal status (>20ng/ml). Those with severe and moderate deficiency were randomly divided into 4 subgroups and received vitamin

  7. Low vaccination coverage of Greek Roma children amid economic crisis: national survey using stratified cluster sampling

    PubMed Central

    Petraki, Ioanna; Arkoudis, Chrisoula; Terzidis, Agis; Smyrnakis, Emmanouil; Benos, Alexis; Panagiotopoulos, Takis

    2017-01-01

    Abstract Background: Research on Roma health is fragmentary as major methodological obstacles often exist. Reliable estimates on vaccination coverage of Roma children at a national level and identification of risk factors for low coverage could play an instrumental role in developing evidence-based policies to promote vaccination in this marginalized population group. Methods: We carried out a national vaccination coverage survey of Roma children. Thirty Roma settlements, stratified by geographical region and settlement type, were included; 7–10 children aged 24–77 months were selected from each settlement using systematic sampling. Information on children’s vaccination coverage was collected from multiple sources. In the analysis we applied weights for each stratum, identified through a consensus process. Results: A total of 251 Roma children participated in the study. A vaccination document was presented for the large majority (86%). We found very low vaccination coverage for all vaccines. In 35–39% of children ‘minimum vaccination’ (DTP3 and IPV2 and MMR1) was administered, while 34–38% had received HepB3 and 31–35% Hib3; no child was vaccinated against tuberculosis in the first year of life. Better living conditions and primary care services close to Roma settlements were associated with higher vaccination indices. Conclusions: Our study showed inadequate vaccination coverage of Roma children in Greece, much lower than that of the non-minority child population. This serious public health challenge should be systematically addressed, or, amid continuing economic recession, the gap may widen. Valid national estimates on important characteristics of the Roma population can contribute to planning inclusion policies. PMID:27694159

  8. Low vaccination coverage of Greek Roma children amid economic crisis: national survey using stratified cluster sampling.

    PubMed

    Papamichail, Dimitris; Petraki, Ioanna; Arkoudis, Chrisoula; Terzidis, Agis; Smyrnakis, Emmanouil; Benos, Alexis; Panagiotopoulos, Takis

    2017-04-01

    Research on Roma health is fragmentary as major methodological obstacles often exist. Reliable estimates on vaccination coverage of Roma children at a national level and identification of risk factors for low coverage could play an instrumental role in developing evidence-based policies to promote vaccination in this marginalized population group. We carried out a national vaccination coverage survey of Roma children. Thirty Roma settlements, stratified by geographical region and settlement type, were included; 7-10 children aged 24-77 months were selected from each settlement using systematic sampling. Information on children's vaccination coverage was collected from multiple sources. In the analysis we applied weights for each stratum, identified through a consensus process. A total of 251 Roma children participated in the study. A vaccination document was presented for the large majority (86%). We found very low vaccination coverage for all vaccines. In 35-39% of children 'minimum vaccination' (DTP3 and IPV2 and MMR1) was administered, while 34-38% had received HepB3 and 31-35% Hib3; no child was vaccinated against tuberculosis in the first year of life. Better living conditions and primary care services close to Roma settlements were associated with higher vaccination indices. Our study showed inadequate vaccination coverage of Roma children in Greece, much lower than that of the non-minority child population. This serious public health challenge should be systematically addressed, or, amid continuing economic recession, the gap may widen. Valid national estimates on important characteristics of the Roma population can contribute to planning inclusion policies. © The Author 2016. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

  9. Field-based random sampling without a sampling frame: control selection for a case-control study in rural Africa.

    PubMed

    Crampin, A C; Mwinuka, V; Malema, S S; Glynn, J R; Fine, P E

    2001-01-01

    Selection bias, particularly of controls, is common in case-control studies and may materially affect the results. Methods of control selection should be tailored both for the risk factors and disease under investigation and for the population being studied. We present here a control selection method devised for a case-control study of tuberculosis in rural Africa (Karonga, northern Malawi) that selects an age/sex frequency-matched random sample of the population, with a geographical distribution in proportion to the population density. We also present an audit of the selection process, and discuss the potential of this method in other settings.

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

    PubMed

    Nguyen, Phuong H; Lowe, Alyssa E; Martorell, Reynaldo; Nguyen, Hieu; Pham, Hoa; Nguyen, Son; Harding, Kimberly B; Neufeld, Lynnette M; Reinhart, Gregory A; Ramakrishnan, Usha

    2012-10-24

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

  11. Forest inventory and stratified estimation: a cautionary note

    Treesearch

    John Coulston

    2008-01-01

    The Forest Inventory and Analysis (FIA) Program uses stratified estimation techniques to produce estimates of forest attributes. Stratification must be unbiased and stratification procedures should be examined to identify any potential bias. This note explains simple techniques for identifying potential bias, discriminating between sample bias and stratification bias,...

  12. Stratifying empiric risk of schizophrenia among first degree relatives using multiple predictors in two independent Indian samples.

    PubMed

    Bhatia, Triptish; Gettig, Elizabeth A; Gottesman, Irving I; Berliner, Jonathan; Mishra, N N; Nimgaonkar, Vishwajit L; Deshpande, Smita N

    2016-12-01

    Schizophrenia (SZ) has an estimated heritability of 64-88%, with the higher values based on twin studies. Conventionally, family history of psychosis is the best individual-level predictor of risk, but reliable risk estimates are unavailable for Indian populations. Genetic, environmental, and epigenetic factors are equally important and should be considered when predicting risk in 'at risk' individuals. To estimate risk based on an Indian schizophrenia participant's family history combined with selected demographic factors. To incorporate variables in addition to family history, and to stratify risk, we constructed a regression equation that included demographic variables in addition to family history. The equation was tested in two independent Indian samples: (i) an initial sample of SZ participants (N=128) with one sibling or offspring; (ii) a second, independent sample consisting of multiply affected families (N=138 families, with two or more sibs/offspring affected with SZ). The overall estimated risk was 4.31±0.27 (mean±standard deviation). There were 19 (14.8%) individuals in the high risk group, 75 (58.6%) in the moderate risk and 34 (26.6%) in the above average risk (in Sample A). In the validation sample, risks were distributed as: high (45%), moderate (38%) and above average (17%). Consistent risk estimates were obtained from both samples using the regression equation. Familial risk can be combined with demographic factors to estimate risk for SZ in India. If replicated, the proposed stratification of risk may be easier and more realistic for family members. Copyright © 2016. Published by Elsevier B.V.

  13. Development and assessment of an e-learning course on breast imaging for radiographers: a stratified randomized controlled trial.

    PubMed

    Moreira, Inês C; Ventura, Sandra Rua; Ramos, Isabel; Rodrigues, Pedro Pereira

    2015-01-05

    Mammography is considered the best imaging technique for breast cancer screening, and the radiographer plays an important role in its performance. Therefore, continuing education is critical to improving the performance of these professionals and thus providing better health care services. Our goal was to develop an e-learning course on breast imaging for radiographers, assessing its efficacy, effectiveness, and user satisfaction. A stratified randomized controlled trial was performed with radiographers and radiology students who already had mammography training, using pre- and post-knowledge tests, and satisfaction questionnaires. The primary outcome was the improvement in test results (percentage of correct answers), using intention-to-treat and per-protocol analysis. A total of 54 participants were assigned to the intervention (20 students plus 34 radiographers) with 53 controls (19+34). The intervention was completed by 40 participants (11+29), with 4 (2+2) discontinued interventions, and 10 (7+3) lost to follow-up. Differences in the primary outcome were found between intervention and control: 21 versus 4 percentage points (pp), P<.001. Stratified analysis showed effect in radiographers (23 pp vs 4 pp; P=.004) but was unclear in students (18 pp vs 5 pp; P=.098). Nonetheless, differences in students' posttest results were found (88% vs 63%; P=.003), which were absent in pretest (63% vs 63%; P=.106). The per-protocol analysis showed a higher effect (26 pp vs 2 pp; P<.001), both in students (25 pp vs 3 pp; P=.004) and radiographers (27 pp vs 2 pp; P<.001). Overall, 85% were satisfied with the course, and 88% considered it successful. This e-learning course is effective, especially for radiographers, which highlights the need for continuing education.

  14. Development and Assessment of an E-Learning Course on Breast Imaging for Radiographers: A Stratified Randomized Controlled Trial

    PubMed Central

    Ventura, Sandra Rua; Ramos, Isabel; Rodrigues, Pedro Pereira

    2015-01-01

    Background Mammography is considered the best imaging technique for breast cancer screening, and the radiographer plays an important role in its performance. Therefore, continuing education is critical to improving the performance of these professionals and thus providing better health care services. Objective Our goal was to develop an e-learning course on breast imaging for radiographers, assessing its efficacy, effectiveness, and user satisfaction. Methods A stratified randomized controlled trial was performed with radiographers and radiology students who already had mammography training, using pre- and post-knowledge tests, and satisfaction questionnaires. The primary outcome was the improvement in test results (percentage of correct answers), using intention-to-treat and per-protocol analysis. Results A total of 54 participants were assigned to the intervention (20 students plus 34 radiographers) with 53 controls (19+34). The intervention was completed by 40 participants (11+29), with 4 (2+2) discontinued interventions, and 10 (7+3) lost to follow-up. Differences in the primary outcome were found between intervention and control: 21 versus 4 percentage points (pp), P<.001. Stratified analysis showed effect in radiographers (23 pp vs 4 pp; P=.004) but was unclear in students (18 pp vs 5 pp; P=.098). Nonetheless, differences in students’ posttest results were found (88% vs 63%; P=.003), which were absent in pretest (63% vs 63%; P=.106). The per-protocol analysis showed a higher effect (26 pp vs 2 pp; P<.001), both in students (25 pp vs 3 pp; P=.004) and radiographers (27 pp vs 2 pp; P<.001). Overall, 85% were satisfied with the course, and 88% considered it successful. Conclusions This e-learning course is effective, especially for radiographers, which highlights the need for continuing education. PMID:25560547

  15. Sampling designs for HIV molecular epidemiology with application to Honduras.

    PubMed

    Shepherd, Bryan E; Rossini, Anthony J; Soto, Ramon Jeremias; De Rivera, Ivette Lorenzana; Mullins, James I

    2005-11-01

    Proper sampling is essential to characterize the molecular epidemiology of human immunodeficiency virus (HIV). HIV sampling frames are difficult to identify, so most studies use convenience samples. We discuss statistically valid and feasible sampling techniques that overcome some of the potential for bias due to convenience sampling and ensure better representation of the study population. We employ a sampling design called stratified cluster sampling. This first divides the population into geographical and/or social strata. Within each stratum, a population of clusters is chosen from groups, locations, or facilities where HIV-positive individuals might be found. Some clusters are randomly selected within strata and individuals are randomly selected within clusters. Variation and cost help determine the number of clusters and the number of individuals within clusters that are to be sampled. We illustrate the approach through a study designed to survey the heterogeneity of subtype B strains in Honduras.

  16. Overweight/obesity and hypertension in schoolchildren aged 6-16 years, Aden Governorate, Yemen, 2009.

    PubMed

    Badi, M A H; Garcia-Triana, B E; Suarez-Martinez, R

    2012-07-01

    Hypertension and obesity in children are increasing concerns worldwide. A cross-sectional study of hypertension in relation to overweight/obesity was conducted in 2009 among schoolchildren aged 6-16 years in Aden, Yemen. Using multistage stratified random sampling 1885 children were classified into wasted, normal weight, overweight and obese according to body mass index. The prevalence of wasting was 10.1%, normal weight 69.2%, overweight 12.7% and obesity 8.0%. The rate of high blood pressure (World Health Organization criteria) was 8.2% for prehypertension and 2.4% for hypertension and was significantly related to the presence of overweight or obesity. Child's body mass index combined with age was a predictor for systolic and diastolic blood pressure. The study provides further evidence that overweight/obesity is associated with hypertension in these schoolchildren.

  17. Prevalence of drug use among drivers based on mandatory, random tests in a roadside survey

    PubMed Central

    Alcañiz, Manuela; Guillen, Montserrat

    2018-01-01

    Background In the context of road safety, this study aims to examine the prevalence of drug use in a random sample of drivers. Methods A stratified probabilistic sample was designed to represent vehicles circulating on non-urban roads. Random drug tests were performed during autumn 2014 on 521 drivers in Catalonia (Spain). Participation was mandatory. The prevalence of drug driving for cannabis, methamphetamines, amphetamines, cocaine, opiates and benzodiazepines was assessed. Results The overall prevalence of drug use is 16.4% (95% CI: 13.9; 18.9) and affects primarily younger male drivers. Drug use is similarly prevalent during weekdays and on weekends, but increases with the number of occupants. The likelihood of being positive for methamphetamines is significantly higher for drivers of vans and lorries. Conclusions Different patterns of use are detected depending on the drug considered. Preventive drug tests should not only be conducted on weekends and at night-time, and need to be reinforced for drivers of commercial vehicles. Active educational campaigns should focus on the youngest age-group of male drivers. PMID:29920542

  18. Comparison of sampling strategies for object-based classification of urban vegetation from Very High Resolution satellite images

    NASA Astrophysics Data System (ADS)

    Rougier, Simon; Puissant, Anne; Stumpf, André; Lachiche, Nicolas

    2016-09-01

    Vegetation monitoring is becoming a major issue in the urban environment due to the services they procure and necessitates an accurate and up to date mapping. Very High Resolution satellite images enable a detailed mapping of the urban tree and herbaceous vegetation. Several supervised classifications with statistical learning techniques have provided good results for the detection of urban vegetation but necessitate a large amount of training data. In this context, this study proposes to investigate the performances of different sampling strategies in order to reduce the number of examples needed. Two windows based active learning algorithms from state-of-art are compared to a classical stratified random sampling and a third combining active learning and stratified strategies is proposed. The efficiency of these strategies is evaluated on two medium size French cities, Strasbourg and Rennes, associated to different datasets. Results demonstrate that classical stratified random sampling can in some cases be just as effective as active learning methods and that it should be used more frequently to evaluate new active learning methods. Moreover, the active learning strategies proposed in this work enables to reduce the computational runtime by selecting multiple windows at each iteration without increasing the number of windows needed.

  19. Health plan auditing: 100-percent-of-claims vs. random-sample audits.

    PubMed

    Sillup, George P; Klimberg, Ronald K

    2011-01-01

    The objective of this study was to examine the relative efficacy of two different methodologies for auditing self-funded medical claim expenses: 100-percent-of-claims auditing versus random-sampling auditing. Multiple data sets of claim errors or 'exceptions' from two Fortune-100 corporations were analysed and compared to 100 simulated audits of 300- and 400-claim random samples. Random-sample simulations failed to identify a significant number and amount of the errors that ranged from $200,000 to $750,000. These results suggest that health plan expenses of corporations could be significantly reduced if they audited 100% of claims and embraced a zero-defect approach.

  20. Latin Hypercube Sampling (LHS) UNIX Library/Standalone

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    2004-05-13

    The LHS UNIX Library/Standalone software provides the capability to draw random samples from over 30 distribution types. It performs the sampling by a stratified sampling method called Latin Hypercube Sampling (LHS). Multiple distributions can be sampled simultaneously, with user-specified correlations amongst the input distributions, LHS UNIX Library/ Standalone provides a way to generate multi-variate samples. The LHS samples can be generated either as a callable library (e.g., from within the DAKOTA software framework) or as a standalone capability. LHS UNIX Library/Standalone uses the Latin Hypercube Sampling method (LHS) to generate samples. LHS is a constrained Monte Carlo sampling scheme. Inmore » LHS, the range of each variable is divided into non-overlapping intervals on the basis of equal probability. A sample is selected at random with respect to the probability density in each interval, If multiple variables are sampled simultaneously, then values obtained for each are paired in a random manner with the n values of the other variables. In some cases, the pairing is restricted to obtain specified correlations amongst the input variables. Many simulation codes have input parameters that are uncertain and can be specified by a distribution, To perform uncertainty analysis and sensitivity analysis, random values are drawn from the input parameter distributions, and the simulation is run with these values to obtain output values. If this is done repeatedly, with many input samples drawn, one can build up a distribution of the output as well as examine correlations between input and output variables.« less

  1. Stratified probabilistic bias analysis for BMI-related exposure misclassification in postmenopausal women.

    PubMed

    Banack, Hailey R; Stokes, Andrew; Fox, Matthew P; Hovey, Kathleen M; Cespedes-Feliciano, Elizabeth M; LeBlanc, Erin; Bird, Chloe; Caan, Bette J; Kroenke, Candyce H; Allison, Matthew A; Going, Scott B; Snetslaar, Linda; Cheng, Ting-Yuan David; Chlebowski, Rowan T; Stefanick, Marcia L; LaMonte, Michael J; Wactawski-Wende, Jean

    2018-06-01

    There is widespread concern about the use of body mass index (BMI) to define obesity status in postmenopausal women because it may not accurately represent an individual's true obesity status. The objective of the present study is to examine and adjust for exposure misclassification bias from using an indirect measure of obesity (BMI) compared with a direct measure of obesity (percent body fat). We used data from postmenopausal non-Hispanic black and non-Hispanic white women in the Women's Health Initiative (WHI; n=126,459). Within the WHI, a sample of 11,018 women were invited to participate in a sub-study involving dual-energy x-ray absorptiometry (DXA) scans. We examined indices of validity comparing BMI-defined obesity (≥30kg/m) with obesity defined by percent body fat. We then used probabilistic bias analysis models stratified by age and race to explore the effect of exposure misclassification on the obesity-mortality relationship. Validation analyses highlight that using a BMI cutpoint of 30 kg/m to define obesity in postmenopausal women is associated with poor validity. There were notable differences in sensitivity by age and race. Results from the stratified bias analysis demonstrated that failing to adjust for exposure misclassification bias results in attenuated estimates of the obesity-mortality relationship. For example, in non-Hispanic white women age 50-59, the conventional risk difference was 0.017 (95% CI 0.01, 0.023) and the bias-adjusted risk difference was 0.035 (95% SI 0.028, 0.043). These results demonstrate the importance of using quantitative bias analysis techniques to account for non-differential exposure misclassification of BMI-defined obesity.

  2. Investigation of spectral analysis techniques for randomly sampled velocimetry data

    NASA Technical Reports Server (NTRS)

    Sree, Dave

    1993-01-01

    It is well known that velocimetry (LV) generates individual realization velocity data that are randomly or unevenly sampled in time. Spectral analysis of such data to obtain the turbulence spectra, and hence turbulence scales information, requires special techniques. The 'slotting' technique of Mayo et al, also described by Roberts and Ajmani, and the 'Direct Transform' method of Gaster and Roberts are well known in the LV community. The slotting technique is faster than the direct transform method in computation. There are practical limitations, however, as to how a high frequency and accurate estimate can be made for a given mean sampling rate. These high frequency estimates are important in obtaining the microscale information of turbulence structure. It was found from previous studies that reliable spectral estimates can be made up to about the mean sampling frequency (mean data rate) or less. If the data were evenly samples, the frequency range would be half the sampling frequency (i.e. up to Nyquist frequency); otherwise, aliasing problem would occur. The mean data rate and the sample size (total number of points) basically limit the frequency range. Also, there are large variabilities or errors associated with the high frequency estimates from randomly sampled signals. Roberts and Ajmani proposed certain pre-filtering techniques to reduce these variabilities, but at the cost of low frequency estimates. The prefiltering acts as a high-pass filter. Further, Shapiro and Silverman showed theoretically that, for Poisson sampled signals, it is possible to obtain alias-free spectral estimates far beyond the mean sampling frequency. But the question is, how far? During his tenure under 1993 NASA-ASEE Summer Faculty Fellowship Program, the author investigated from his studies on the spectral analysis techniques for randomly sampled signals that the spectral estimates can be enhanced or improved up to about 4-5 times the mean sampling frequency by using a suitable

  3. Prevalence and Risk Factors of Dengue Infection in Khanh Hoa Province, Viet Nam: A Stratified Cluster Sampling Survey.

    PubMed

    Mai, Vien Quang; Mai, Trịnh Thị Xuan; Tam, Ngo Le Minh; Nghia, Le Trung; Komada, Kenichi; Murakami, Hitoshi

    2018-05-19

    Dengue is a clinically important arthropod-borne viral disease with increasing global incidence. Here we aimed to estimate the prevalence of dengue infections in Khanh Hoa Province, central Viet Nam, and to identify risk factors for infection. We performed a stratified cluster sampling survey including residents of 3-60 years of age in Nha Trang City, Ninh Hoa District and Dien Khanh District, Khanh Hoa Province, in October 2011. Immunoglobulin G (IgG) and immunoglobulin M (IgM) against dengue were analyzed using a rapid test kit. Participants completed a questionnaire exploring clinical dengue incidence, socio-economic status, and individual behavior. A household checklist was used to examine environment, mosquito larvae presence, and exposure to public health interventions. IgG positivity was 20.5% (urban, 16.3%; rural, 23.0%), IgM positivity was 6.7% (urban, 6.4%; rural, 6.9%), and incidence of clinically compatible dengue during the prior 3 months was 2.8 per 1,000 persons (urban, 1.7; rural, 3.4). For IgG positivity, the adjusted odds ratio (AOR) was 2.68 (95% confidence interval [CI], 1.24-5.81) for mosquito larvae presence in water pooled in old tires and was 3.09 (95% CI, 1.75-5.46) for proximity to a densely inhabited area. For IgM positivity, the AOR was 3.06 (95% CI, 1.50-6.23) for proximity to a densely inhabited area. Our results indicated rural penetration of dengue infections. Control measures should target densely inhabited areas, and may include clean-up of discarded tires and water-collecting waste.

  4. Outpatient Dermatological Diagnoses in Spain: Results From the National DIADERM Random Sampling Project.

    PubMed

    Buendía-Eisman, A; Arias-Santiago, S; Molina-Leyva, A; Gilaberte, Y; Fernández-Crehuet, P; Husein-ElAhmed, H; Viera-Ramírez, A; Fernández-Peñas, P; Taberner, R; Descalzo, M Á; García-Doval, I

    2018-06-01

    Dermatologists perform most of their work in outpatient or private clinics. Data on the diagnoses made by dermatologists in these settings are lacking, however, as outpatient activity, unlike hospital activity, is difficult to code. The aim of this study was to analyze the diagnoses made by members of the Spanish Academy of Dermatology and Venereology (AEDV) at dermatology clinics in Spain. We selected a random sample of AEDV dermatologists drawn from the AEDV list and stratified by geographic area. The selected dermatologists received instructions on how to collect the data required. Each participant recorded the diagnosis reached and other data for patients seen during 2 specified periods: 3 days in January and 3 days in May. The diagnoses were subsequently coded by a dermatologist expert in applying the International Classification of Diseases (10th revision). In view of the complex nature of the sample, data were analyzed with standard error and finite population corrections. The sample consisted of 124 dermatologists. Of these, 65% participated in the first phase of the study and 59% in the second. An estimated 621 562 patients (95% CI, 368 130-874 995) visit the dermatologist every month in Spain. This is the equivalent of 28 (25-31) patients per day per clinic. The most common diagnosis recorded was actinic keratosis, followed by basal cell carcinoma and melanocytic nevus. The vast majority of visits took place at the clinic, but 1% of patients (0.3%-3%) were assessed using teledermatology. This is the first study in Spain to analyze diagnoses made by AEDV members at outpatient dermatology clinics. Our findings show a high volume of activity and will be useful for guiding health care planning, resource use, and future studies. Copyright © 2018. Publicado por Elsevier España, S.L.U.

  5. Elevated manganese exposure and school-aged children's behavior: a gender-stratified analysis.

    PubMed

    Menezes-Filho, José A; de Carvalho-Vivas, Chrissie F; Viana, Gustavo F S; Ferreira, Junia R D; Nunes, Lorena S; Mergler, Donna; Abreu, Neander

    2014-12-01

    High levels of waterborne manganese have been associated with problematic behavior in school-aged children, however to date this has not been reported for children exposed to airborne manganese. The objective of the present study was to examine behavioral traits among children with exposure to airborne manganese from a ferro-manganese alloy plant, located in the metropolitan region of Salvador, Brazil. The study included 34 boys and 36 girls, aged 7-12 years, living in two communities within a 3-km radius from the plant. For each child, hair manganese levels (MnH) and blood lead (PbB) levels were analyzed by graphite furnace atomic absorption spectrometry. The Children's Behavior Check List (CBCL) (Portuguese version validated in Brazil) was administered to parents or caregivers, providing scale scores of internalizing (withdrawn, somatic complaints, and anxious/depressed scales), externalizing (disruptive and aggressive) behaviors and a separate scale for attention problems. Median and range for MnH and PbB were 11.48 μg/g (range: 0.52-55.74); 1.1 μg/dL (range: 0.5-6.1), respectively. Spearman correlation analyses showed that several behavioral indices were significantly correlated with MnH levels for girls, but not for boys: total externalizing behavior (rho=0.484 vs rho=0.041) and attention problem scores (rho=0.542 vs rho=0.003) coefficients were significantly at p<0.001 level, respectively for girls and boys. No significant correlation was observed with any of the internalizing sub-scales. A linear regression model was fitted with the total externalizing behavior, inattention and total CBCL scores as dependent variables, with log transformed MnH stratified by sex, adjusting for age and maternal IQ. Total externalizing behaviors and attention problem scores were significantly associated with girls' MnH levels but not with boys'. Adjusting for maternal IQ, the β-coefficients for LogMnH associations with total externalizing and attention problems are 8.85 (95

  6. Information content of household-stratified epidemics.

    PubMed

    Kinyanjui, T M; Pellis, L; House, T

    2016-09-01

    Household structure is a key driver of many infectious diseases, as well as a natural target for interventions such as vaccination programs. Many theoretical and conceptual advances on household-stratified epidemic models are relatively recent, but have successfully managed to increase the applicability of such models to practical problems. To be of maximum realism and hence benefit, they require parameterisation from epidemiological data, and while household-stratified final size data has been the traditional source, increasingly time-series infection data from households are becoming available. This paper is concerned with the design of studies aimed at collecting time-series epidemic data in order to maximize the amount of information available to calibrate household models. A design decision involves a trade-off between the number of households to enrol and the sampling frequency. Two commonly used epidemiological study designs are considered: cross-sectional, where different households are sampled at every time point, and cohort, where the same households are followed over the course of the study period. The search for an optimal design uses Bayesian computationally intensive methods to explore the joint parameter-design space combined with the Shannon entropy of the posteriors to estimate the amount of information in each design. For the cross-sectional design, the amount of information increases with the sampling intensity, i.e., the designs with the highest number of time points have the most information. On the other hand, the cohort design often exhibits a trade-off between the number of households sampled and the intensity of follow-up. Our results broadly support the choices made in existing epidemiological data collection studies. Prospective problem-specific use of our computational methods can bring significant benefits in guiding future study designs. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  7. A Multilevel, Hierarchical Sampling Technique for Spatially Correlated Random Fields

    DOE PAGES

    Osborn, Sarah; Vassilevski, Panayot S.; Villa, Umberto

    2017-10-26

    In this paper, we propose an alternative method to generate samples of a spatially correlated random field with applications to large-scale problems for forward propagation of uncertainty. A classical approach for generating these samples is the Karhunen--Loève (KL) decomposition. However, the KL expansion requires solving a dense eigenvalue problem and is therefore computationally infeasible for large-scale problems. Sampling methods based on stochastic partial differential equations provide a highly scalable way to sample Gaussian fields, but the resulting parametrization is mesh dependent. We propose a multilevel decomposition of the stochastic field to allow for scalable, hierarchical sampling based on solving amore » mixed finite element formulation of a stochastic reaction-diffusion equation with a random, white noise source function. Lastly, numerical experiments are presented to demonstrate the scalability of the sampling method as well as numerical results of multilevel Monte Carlo simulations for a subsurface porous media flow application using the proposed sampling method.« less

  8. A Multilevel, Hierarchical Sampling Technique for Spatially Correlated Random Fields

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Osborn, Sarah; Vassilevski, Panayot S.; Villa, Umberto

    In this paper, we propose an alternative method to generate samples of a spatially correlated random field with applications to large-scale problems for forward propagation of uncertainty. A classical approach for generating these samples is the Karhunen--Loève (KL) decomposition. However, the KL expansion requires solving a dense eigenvalue problem and is therefore computationally infeasible for large-scale problems. Sampling methods based on stochastic partial differential equations provide a highly scalable way to sample Gaussian fields, but the resulting parametrization is mesh dependent. We propose a multilevel decomposition of the stochastic field to allow for scalable, hierarchical sampling based on solving amore » mixed finite element formulation of a stochastic reaction-diffusion equation with a random, white noise source function. Lastly, numerical experiments are presented to demonstrate the scalability of the sampling method as well as numerical results of multilevel Monte Carlo simulations for a subsurface porous media flow application using the proposed sampling method.« less

  9. Resource Input, Service Process and Resident Activity Indicators in a Welsh National Random Sample of Staffed Housing Services for People with Intellectual Disabilities

    ERIC Educational Resources Information Center

    Felce, David; Perry, Jonathan

    2004-01-01

    Background: The aims were to: (i) explore the association between age and size of setting and staffing per resident; and (ii) report resident and setting characteristics, and indicators of service process and resident activity for a national random sample of staffed housing provision. Methods: Sixty settings were selected randomly from those…

  10. The Association Between Body Mass Index and Open-angle Glaucoma in a South Korean Population-based Sample.

    PubMed

    Lin, Shuai-Chun; Pasquale, Louis R; Singh, Kuldev; Lin, Shan C

    2018-03-01

    The purpose of this article is to investigate the association between body mass index (BMI) and open-angle glaucoma (OAG) in a sample of the South Korean population. The sample consisted of a cross-sectional, population-based sample of 10,978 participants, 40 years of age and older, enrolled in the 2008 to 2011 Korean National Health and Nutrition Examination Survey. All participants had measured intraocular pressure <22 mm Hg and open anterior chamber angles. OAG was defined using disc and visual field criteria established by the International Society for Geographical and Epidemiological Ophthalmology. Multivariable analyses were performed to determine the association between BMI and OAG. These analyses were also performed in a sex-stratified and age-stratified manner. After adjusting for potential confounding variables, lower BMI (<19 kg/m) was associated with greater risk of OAG compared with normal BMI (19 to 24.9 kg/m) [odds ratio (OR), 2.28; 95% confidence interval (CI), 1.22-4.26]. In sex-stratified analyses, low BMI remained adversely related to glaucoma in women (OR, 3.45; 95% CI, 1.42-8.38) but not in men (OR, 1.72; 95% CI, 0.71-4.20). In age-stratified analyses, lower BMI was adversely related to glaucoma among subjects 40- to 49-year old (OR, 5.16; 95% CI, 1.86-14.36) but differences in glaucoma prevalence were not statistically significant between those with low versus normal BMI in other age strata. Lower BMI was associated with increased odds of OAG in a sample of the South Korean population. Multivariate analysis revealed the association to be statistically significant in women and those in the youngest age stratum.

  11. Insulation workers in Belfast. 1. Comparison of a random sample with a control population1

    PubMed Central

    Wallace, William F. M.; Langlands, Jean H. M.

    1971-01-01

    Wallace, W. F. M., and Langlands, J. H. M. (1971).Brit. J. industr. Med.,28, 211-216. Insulation workers in Belfast. 1. Comparison of a random sample with a control population. A sample of 50 men was chosen at random from the population of asbestos insulators in Belfast and matched with a control series of men of similar occupational group with respect to age, height, and smoking habit. Significantly more of the insulators complained of cough and sputum and had basal rales on examination. Clubbing was assessed by means of measurements of the hyponychial angle of both index fingers. These angles were significantly greater in the group of insulators. Twenty-one insulators had ϰ-rays which showed pleural calcification with or without pulmonary fibrosis; one control ϰ-ray showed pulmonary fibrosis. The insulators had no evidence of airways obstruction but static lung volume was reduced and their arterial oxygen tension was lower than that of the controls and their alveolar-arterial oxygen gradient was greater. PMID:5557841

  12. Employment status, inflation and suicidal behaviour: an analysis of a stratified sample in Italy.

    PubMed

    Solano, Paola; Pizzorno, Enrico; Gallina, Anna M; Mattei, Chiara; Gabrielli, Filippo; Kayman, Joshua

    2012-09-01

    There is abundant empirical evidence of a surplus risk of suicide among the unemployed, although few studies have investigated the influence of economic downturns on suicidal behaviours in an employment status-stratified sample. We investigated how economic inflation affected suicidal behaviours according to employment status in Italy from 2001 to 2008. Data concerning economically active people were provided by the Italian Institute for Statistical Analysis and by the International Monetary Fund. The association between inflation and completed versus attempted suicide with respect to employment status was investigated in every year and quarter-year of the study time frame. We considered three occupational categories: employed, unemployed who were previously employed and unemployed who had never worked. The unemployed are at higher suicide risk than the employed. Among the PE, a significant association between inflation and suicide attempt was found, whereas no association was reported concerning completed suicides. No association was found between completed and attempted suicides among the employed, the NE and inflation. Completed suicide in females is significantly associated with unemployment in every quarter-year. The reported vulnerability to suicidal behaviours among the PE as inflation rises underlines the need of effective support strategies for both genders in times of economic downturns.

  13. Health literacy in old age: results of a German cross-sectional study.

    PubMed

    Vogt, Dominique; Schaeffer, Doris; Messer, Melanie; Berens, Eva-Maria; Hurrelmann, Klaus

    2017-03-22

    Health literacy is especially important for older people to maintain or enhance remaining health resources and self-management skills. The aim of the study was to determine the level of health literacy and the association between health literacy, demographic and socio-economic factors in German older adults aged 65 years and above stratified by age group. Health literacy was assessed via computer-assisted personal interviews using HLS-EU-Q47 on a representative sample of the German-speaking population. Descriptive statistics, bivariate analyses and logistic regression modelling stratified by age group were conducted to assess health literacy of 475 respondents aged 65 years and above. Overall, 66.3% of all respondents aged 65 years and above had limited health literacy. Limited health literacy was especially prevalent among respondents above 76 years of age (80.6%). Limited health literacy was associated with financial deprivation (OR: 3.05; 95% CI: 1.99-4.67) and limited functional health literacy (OR: 2.16; 95% CI: 1.29-3.61). Financial deprivation was strongest predictor for limited health literacy in the total sample and stratified by age group. Limited health literacy is a frequent phenomenon in German adults aged 65 years and above. Research on health literacy in old age and the role in health disparities is urgently needed. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  14. Emotional Experience Improves With Age: Evidence Based on Over 10 Years of Experience Sampling

    PubMed Central

    Carstensen, Laura L.; Turan, Bulent; Scheibe, Susanne; Ram, Nilam; Ersner-Hershfield, Hal; Samanez-Larkin, Gregory R.; Brooks, Kathryn P.; Nesselroade, John R.

    2012-01-01

    Recent evidence suggests that emotional well-being improves from early adulthood to old age. This study used experience-sampling to examine the developmental course of emotional experience in a representative sample of adults spanning early to very late adulthood. Participants (N = 184, Wave 1; N = 191, Wave 2; N = 178, Wave 3) reported their emotional states at five randomly selected times each day for a one week period. Using a measurement burst design, the one-week sampling procedure was repeated five and then ten years later. Cross-sectional and growth curve analyses indicate that aging is associated with more positive overall emotional well-being, with greater emotional stability and with more complexity (as evidenced by greater co-occurrence of positive and negative emotions). These findings remained robust after accounting for other variables that may be related to emotional experience (personality, verbal fluency, physical health, and demographic variables). Finally, emotional experience predicted mortality; controlling for age, sex, and ethnicity, individuals who experienced relatively more positive than negative emotions in everyday life were more likely to have survived over a 13 year period. Findings are discussed in the theoretical context of socioemotional selectivity theory. PMID:20973600

  15. Systematic random sampling of the comet assay.

    PubMed

    McArt, Darragh G; Wasson, Gillian R; McKerr, George; Saetzler, Kurt; Reed, Matt; Howard, C Vyvyan

    2009-07-01

    The comet assay is a technique used to quantify DNA damage and repair at a cellular level. In the assay, cells are embedded in agarose and the cellular content is stripped away leaving only the DNA trapped in an agarose cavity which can then be electrophoresed. The damaged DNA can enter the agarose and migrate while the undamaged DNA cannot and is retained. DNA damage is measured as the proportion of the migratory 'tail' DNA compared to the total DNA in the cell. The fundamental basis of these arbitrary values is obtained in the comet acquisition phase using fluorescence microscopy with a stoichiometric stain in tandem with image analysis software. Current methods deployed in such an acquisition are expected to be both objectively and randomly obtained. In this paper we examine the 'randomness' of the acquisition phase and suggest an alternative method that offers both objective and unbiased comet selection. In order to achieve this, we have adopted a survey sampling approach widely used in stereology, which offers a method of systematic random sampling (SRS). This is desirable as it offers an impartial and reproducible method of comet analysis that can be used both manually or automated. By making use of an unbiased sampling frame and using microscope verniers, we are able to increase the precision of estimates of DNA damage. Results obtained from a multiple-user pooled variation experiment showed that the SRS technique attained a lower variability than that of the traditional approach. The analysis of a single user with repetition experiment showed greater individual variances while not being detrimental to overall averages. This would suggest that the SRS method offers a better reflection of DNA damage for a given slide and also offers better user reproducibility.

  16. Association between Spouse/Child Separation and Migration-Related Stress among a Random Sample of Rural-to-Urban Migrants in Wuhan, China

    PubMed Central

    Guo, Yan; Chen, Xinguang; Gong, Jie; Li, Fang; Zhu, Chaoyang; Yan, Yaqiong; Wang, Liang

    2016-01-01

    Background Millions of people move from rural areas to urban areas in China to pursue new opportunities while leaving their spouses and children at rural homes. Little is known about the impact of migration-related separation on mental health of these rural migrants in urban China. Methods Survey data from a random sample of rural-to-urban migrants (n = 1113, aged 18–45) from Wuhan were analyzed. The Domestic Migration Stress Questionnaire (DMSQ), an instrument with four subconstructs, was used to measure migration-related stress. The relationship between spouse/child separation and stress was assessed using survey estimation methods to account for the multi-level sampling design. Results 16.46% of couples were separated from their spouses (spouse-separation only), 25.81% of parents were separated from their children (child separation only). Among the participants who married and had children, 5.97% were separated from both their spouses and children (double separation). Spouse-separation only and double separation did not scored significantly higher on DMSQ than those with no separation. Compared to parents without child separation, parents with child separation scored significantly higher on DMSQ (mean score = 2.88, 95% CI: [2.81, 2.95] vs. 2.60 [2.53, 2.67], p < .05). Stratified analysis by separation type and by gender indicated that the association was stronger for child-separation only and for female participants. Conclusion Child-separation is an important source of migration-related stress, and the effect is particularly strong for migrant women. Public policies and intervention programs should consider these factors to encourage and facilitate the co-migration of parents with their children to mitigate migration-related stress. PMID:27124768

  17. Association between Spouse/Child Separation and Migration-Related Stress among a Random Sample of Rural-to-Urban Migrants in Wuhan, China.

    PubMed

    Guo, Yan; Chen, Xinguang; Gong, Jie; Li, Fang; Zhu, Chaoyang; Yan, Yaqiong; Wang, Liang

    2016-01-01

    Millions of people move from rural areas to urban areas in China to pursue new opportunities while leaving their spouses and children at rural homes. Little is known about the impact of migration-related separation on mental health of these rural migrants in urban China. Survey data from a random sample of rural-to-urban migrants (n = 1113, aged 18-45) from Wuhan were analyzed. The Domestic Migration Stress Questionnaire (DMSQ), an instrument with four subconstructs, was used to measure migration-related stress. The relationship between spouse/child separation and stress was assessed using survey estimation methods to account for the multi-level sampling design. 16.46% of couples were separated from their spouses (spouse-separation only), 25.81% of parents were separated from their children (child separation only). Among the participants who married and had children, 5.97% were separated from both their spouses and children (double separation). Spouse-separation only and double separation did not scored significantly higher on DMSQ than those with no separation. Compared to parents without child separation, parents with child separation scored significantly higher on DMSQ (mean score = 2.88, 95% CI: [2.81, 2.95] vs. 2.60 [2.53, 2.67], p < .05). Stratified analysis by separation type and by gender indicated that the association was stronger for child-separation only and for female participants. Child-separation is an important source of migration-related stress, and the effect is particularly strong for migrant women. Public policies and intervention programs should consider these factors to encourage and facilitate the co-migration of parents with their children to mitigate migration-related stress.

  18. Sex- and age-specific associations between major depressive disorder and metabolic syndrome in two general population samples in Germany.

    PubMed

    Block, Andrea; Schipf, Sabine; Van der Auwera, Sandra; Hannemann, Anke; Nauck, Matthias; John, Ulrich; Völzke, Henry; Freyberger, Harald Jürgen; Dörr, Marcus; Felix, Stephan; Zygmunt, Marek; Wallaschofski, Henri; Grabe, Hans Jörgen

    2016-11-01

    Major depressive disorder (MDD) has been associated with the Metabolic Syndrome (MetS). As previous data strongly suggested sex and age effects on this association, this study aimed to analyse the association between MDD and MetS in two general population samples under explicit consideration of sex and age. This study analysed cross-sectional data based on two independent general population samples: SHIP-0 (n = 4083; 20-81 years; 49.4% male) and SHIP-TREND-0 (n = 3957; 20-83 years; 49.0% male) that were part of the Study of Health in Pomerania. MDD (SHIP-0: 12.6%; SHIP-TREND-0: 27.2%) was assessed using the Composite International Diagnostic-Screener (CID-S) in both samples. Interview assessment of MDD diagnosis according to Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) criteria was performed in SHIP-TREND-0 (18.1% MDD). MetS was defined by abdominal obesity, elevated blood pressure, elevated glucose, elevated triglycerides and reduced high-density lipoprotein cholesterol according to established criteria. Data analysis was performed sex- and age-stratified. Prevalence of MetS was high in both samples: 19.4% of females and 30.2% of males in SHIP-0 and 22.1% and 33.2% in SHIP-TREND-0, respectively. Effect modifications were observed by sex and age on the association between MDD and MetS. Particularly, younger females (20-49 years) with MDD were more often affected by MetS than younger females without MDD: OR = 2.21 (95% CI = 1.39-3.50). This association vanished in elderly participants (50-82 years). The data suggest that especially younger (presumably pre-menopausal) females with MDD are more likely to have MetS than those without major depressive disorders, and that age extenuates this association.

  19. Support of personalized medicine through risk-stratified treatment recommendations - an environmental scan of clinical practice guidelines

    PubMed Central

    2013-01-01

    Background Risk-stratified treatment recommendations facilitate treatment decision-making that balances patient-specific risks and preferences. It is unclear if and how such recommendations are developed in clinical practice guidelines (CPGs). Our aim was to assess if and how CPGs develop risk-stratified treatment recommendations for the prevention or treatment of common chronic diseases. Methods We searched the United States National Guideline Clearinghouse for US, Canadian and National Institute for Health and Clinical Excellence (United Kingdom) CPGs for heart disease, stroke, cancer, chronic obstructive pulmonary disease and diabetes that make risk-stratified treatment recommendations. We included only those CPGs that made risk-stratified treatment recommendations based on risk assessment tools. Two reviewers independently identified CPGs and extracted information on recommended risk assessment tools; type of evidence about treatment benefits and harms; methods for linking risk estimates to treatment evidence and for developing treatment thresholds; and consideration of patient preferences. Results We identified 20 CPGs that made risk-stratified treatment recommendations out of 133 CPGs that made any type of treatment recommendations for the chronic diseases considered in this study. Of the included 20 CPGs, 16 (80%) used evidence about treatment benefits from randomized controlled trials, meta-analyses or other guidelines, and the source of evidence was unclear in the remaining four (20%) CPGs. Nine CPGs (45%) used evidence on harms from randomized controlled trials or observational studies, while 11 CPGs (55%) did not clearly refer to harms. Nine CPGs (45%) explained how risk prediction and evidence about treatments effects were linked (for example, applying estimates of relative risk reductions to absolute risks), but only one CPG (5%) assessed benefit and harm quantitatively and three CPGs (15%) explicitly reported consideration of patient preferences

  20. Survival analysis of cervical cancer using stratified Cox regression

    NASA Astrophysics Data System (ADS)

    Purnami, S. W.; Inayati, K. D.; Sari, N. W. Wulan; Chosuvivatwong, V.; Sriplung, H.

    2016-04-01

    Cervical cancer is one of the mostly widely cancer cause of the women death in the world including Indonesia. Most cervical cancer patients come to the hospital already in an advanced stadium. As a result, the treatment of cervical cancer becomes more difficult and even can increase the death's risk. One of parameter that can be used to assess successfully of treatment is the probability of survival. This study raises the issue of cervical cancer survival patients at Dr. Soetomo Hospital using stratified Cox regression based on six factors such as age, stadium, treatment initiation, companion disease, complication, and anemia. Stratified Cox model is used because there is one independent variable that does not satisfy the proportional hazards assumption that is stadium. The results of the stratified Cox model show that the complication variable is significant factor which influent survival probability of cervical cancer patient. The obtained hazard ratio is 7.35. It means that cervical cancer patient who has complication is at risk of dying 7.35 times greater than patient who did not has complication. While the adjusted survival curves showed that stadium IV had the lowest probability of survival.

  1. A guide for the utilization of Health Insurance Review and Assessment Service National Patient Samples

    PubMed Central

    Kim, Logyoung; Kim, Jee-Ae; Kim, Sanghyun

    2014-01-01

    The claims data of the Health Insurance Review and Assessment Service (HIRA) is an important source of information for healthcare service research. The claims data of HIRA is collected when healthcare service providers submit a claim to HIRA to be reimbursed for a service that they provided to patients. To improve the accessibility of healthcare service researchers to claims data of HIRA, HIRA has developed the Patient Samples which are extracted using a stratified randomized sampling method. The Patient Samples of HIRA consist of five tables: a table for general information (Table 20) containing socio-demographic information such as gender, age and medical aid, indicators for inpatient and outpatient services; a table for specific information on healthcare services provided (Table 30); a table for diagnostic information (Table 40); a table for outpatient prescriptions (Table 53) and a table for information on healthcare service providers (Table of providers). Researchers who are interested in using the Patient Sample data for research can apply via HIRA’s website (https://www.hira.or.kr). PMID:25078381

  2. Panels of tumor-derived RNA markers in peripheral blood of patients with non-small cell lung cancer: their dependence on age, gender and clinical stages.

    PubMed

    Chian, Chih-Feng; Hwang, Yi-Ting; Terng, Harn-Jing; Lee, Shih-Chun; Chao, Tsui-Yi; Chang, Hung; Ho, Ching-Liang; Wu, Yi-Ying; Perng, Wann-Cherng

    2016-08-02

    Peripheral blood mononuclear cell (PBMC)-derived gene signatures were investigated for their potential use in the early detection of non-small cell lung cancer (NSCLC). In our study, 187 patients with NSCLC and 310 age- and gender-matched controls, and an independent set containing 29 patients for validation were included. Eight significant NSCLC-associated genes were identified, including DUSP6, EIF2S3, GRB2, MDM2, NF1, POLDIP2, RNF4, and WEE1. The logistic model containing these significant markers was able to distinguish subjects with NSCLC from controls with an excellent performance, 80.7% sensitivity, 90.6% specificity, and an area under the receiver operating characteristic curve (AUC) of 0.924. Repeated random sub-sampling for 100 times was used to validate the performance of classification training models with an average AUC of 0.92. Additional cross-validation using the independent set resulted in the sensitivity 75.86%. Furthermore, six age/gender-dependent genes: CPEB4, EIF2S3, GRB2, MCM4, RNF4, and STAT2 were identified using age and gender stratification approach. STAT2 and WEE1 were explored as stage-dependent using stage-stratified subpopulation. We conclude that these logistic models using different signatures for total and stratified samples are potential complementary tools for assessing the risk of NSCLC.

  3. Recording 2-D Nutation NQR Spectra by Random Sampling Method

    PubMed Central

    Sinyavsky, Nikolaj; Jadzyn, Maciej; Ostafin, Michal; Nogaj, Boleslaw

    2010-01-01

    The method of random sampling was introduced for the first time in the nutation nuclear quadrupole resonance (NQR) spectroscopy where the nutation spectra show characteristic singularities in the form of shoulders. The analytic formulae for complex two-dimensional (2-D) nutation NQR spectra (I = 3/2) were obtained and the condition for resolving the spectral singularities for small values of an asymmetry parameter η was determined. Our results show that the method of random sampling of a nutation interferogram allows significant reduction of time required to perform a 2-D nutation experiment and does not worsen the spectral resolution. PMID:20949121

  4. Scan-stratified case-control sampling for modeling blood-brain barrier integrity in multiple sclerosis.

    PubMed

    Pomann, Gina-Maria; Sweeney, Elizabeth M; Reich, Daniel S; Staicu, Ana-Maria; Shinohara, Russell T

    2015-09-10

    Multiple sclerosis (MS) is an immune-mediated neurological disease that causes morbidity and disability. In patients with MS, the accumulation of lesions in the white matter of the brain is associated with disease progression and worse clinical outcomes. Breakdown of the blood-brain barrier in newer lesions is indicative of more active disease-related processes and is a primary outcome considered in clinical trials of treatments for MS. Such abnormalities in active MS lesions are evaluated in vivo using contrast-enhanced structural MRI, during which patients receive an intravenous infusion of a costly magnetic contrast agent. In some instances, the contrast agents can have toxic effects. Recently, local image regression techniques have been shown to have modest performance for assessing the integrity of the blood-brain barrier based on imaging without contrast agents. These models have centered on the problem of cross-sectional classification in which patients are imaged at a single study visit and pre-contrast images are used to predict post-contrast imaging. In this paper, we extend these methods to incorporate historical imaging information, and we find the proposed model to exhibit improved performance. We further develop scan-stratified case-control sampling techniques that reduce the computational burden of local image regression models, while respecting the low proportion of the brain that exhibits abnormal vascular permeability. Copyright © 2015 John Wiley & Sons, Ltd.

  5. Steinhaus’ Geometric Location Problem for Random Samples in the Plane.

    DTIC Science & Technology

    1982-05-11

    NAL 411R A1, ’I 7 - I STEINHAUS ’ GEOMETRIC LOCATION PROBLEM FOR RANDOM SAMPLES IN THE PLANE By Dorit Hochbaum and J. Michael Steele TECHNICAL REPORT...DEPARTMENT OF STATISTICS -Dltrib’ytion/ STANFORD UNIVERSITY A-I.abilty Codes STANFORD, CALIFORNIA Dist Spciat ecial Steinhaus ’ Geometric Location Problem for...Random Samples in the Plane By Dorit Hochbaum and J. Michael Steele I. Introduction. The work of H. Steinhaus U wf94 as apparently the first explicit

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

    NASA Astrophysics Data System (ADS)

    Plevnik, Lucijan; Zerovnik, Gašper

    2017-09-01

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

  7. A community-wide campaign to promote physical activity in middle-aged and elderly people: a cluster randomized controlled trial

    PubMed Central

    2013-01-01

    Background We aimed to evaluate the effectiveness of a community-wide campaign (CWC) for promoting physical activity in middle-aged and elderly people. Methods A cluster randomized controlled trial (RCT) with a community as the unit of randomization was performed using a population-based random-sampled evaluation by self-administered questionnaires in the city of Unnan, Shimane Prefecture, Japan. The evaluation sample included 6000 residents aged 40 to 79 years. We randomly allocated nine communities to the intervention group and three to the control group. The intervention was a CWC from 2009 to 2010 to promote physical activity, and it comprised information, education, and support delivery. The primary outcome was a change in engaging in regular aerobic, flexibility, and/or muscle-strengthening activities evaluated at the individual level. Results In total, 4414 residents aged 40–79 years responded to a self-administered questionnaire (73.6% response rate). Awareness of the CWC was 79% in the intervention group. Awareness and knowledge were significantly different between the intervention and control groups, although there were no significant differences in belief and intention. The 1-year CWC did not significantly promote the recommended level of physical activity (adjusted odds ratio: 0.97; 95% confidence interval: 0.84–1.14). Conclusions This cluster RCT showed that the CWC did not promote physical activity in 1 year. Significant differences were observed in awareness and knowledge between intervention and control groups as short-term impacts of the campaign. Trial registration UMIN-CTR UMIN000002683 PMID:23570536

  8. The linear trend of headache prevalence and some headache features in school children.

    PubMed

    Ozge, Aynur; Buğdayci, Resul; Saşmaz, Tayyar; Kaleağasi, Hakan; Kurt, Oner; Karakelle, Ali; Siva, Aksel

    2007-04-01

    The objectives of this study were to determine the age and sex dependent linear trend of recurrent headache prevalence in schoolchildren in Mersin. A stratified sample composed of 5562 children; detailed characteristics were previously published. In this study the prevalence distribution of headache by age and sex showed a peak in the female population at the age of 11 (27.2%) with a plateau in the following years. The great stratified random sample results suggested that, in addition to socio-demographic features, detailed linear trend analysis showed headache features of children with headache have some specific characteristics dependent on age, gender and headache type. This study results can constitute a basis for the future epidemiological based studies.

  9. Change in Coping and Defense Mechanisms across Adulthood: Longitudinal Findings in a European American Sample

    ERIC Educational Resources Information Center

    Diehl, Manfred; Chui, Helena; Hay, Elizabeth L.; Lumley, Mark A.; Grühn, Daniel; Labouvie-Vief, Gisela

    2014-01-01

    This study examined longitudinal changes in coping and defense mechanisms in an age- and gender-stratified sample of 392 European American adults. Nonlinear age-related changes were found for the coping mechanisms of sublimation and suppression and the defense mechanisms of intellectualization, doubt, displacement, and regression. The change…

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

    PubMed

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

    2012-09-15

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

  11. Use of psychotherapy in a representative adult community sample in São Paulo, Brazil

    PubMed Central

    Blay, Sergio L.; Fillenbaum, Gerda G.; da Silva, Paula Freitas R.; Peluso, Erica T.

    2014-01-01

    Little is known about the use of psychotherapy to treat common mental disorders in a major city in a middle income country. Data come from in-home interviews with a stratified random sample of 2,000 community residents age 18–65 in the city of São Paulo, Brazil. The information obtained included sociodemographic characteristics; psychotropic drugs; mental status; and lifetime, previous 12 months, and current use of psychotherapy. Logistic regression was used to examine determinants of use of psychotherapy. Of the sample, 22.7% met General Health Questionnaire-12 criteria for common mental disorders. Lifetime, previous 12 months, and current use of psychotherapy were reported by 14.6%, 4.6%, and 2.3% of the sample respectively. Users were typically women, more educated, higher income, not married, unemployed, with common mental disorders. Further analysis found that 47% (with higher education and income) paid out-of-pocket, and 53% used psychotropic medication. Psychotherapy does not appear to be the preferred treatment for common mental disorders. PMID:25118139

  12. [Is Work in Older Age Healthy? Findings from Family Run Businesses Using the Example of Bavarian Rural Economics].

    PubMed

    Hetzel, C; Holzer, M; Allinger, F; Watzele, R; Hörmann, G; Weber, A

    2016-05-01

    Working in second half of life is individually and socially important. The aim of this study is to multidimensionally evaluate the subjective health situation of older people, in particular those beyond the legal age of retirement who are working or assisting in family run businesses, using the example of Bavarian rural economics. A 3 stage random sample stratified proportionally to regional population numbers was selected for a cross-sectional questionnaire survey (personal delivery, postal return n=3 176, 39.1%). Sample results can be generalised (men 59.8%, at least 65 years old 60.8%, smallest/small enterprises 61.8%). Life satisfaction is similar to that of the German age cohort population. In comparison to commercial and technical fields, physic and psychological complaints are lower and work pleasure is much higher. Health indicators are not dependent on enterprise structures, but on age and gender - on age partly non-linearly. Our results indicate that working in older age can be a source of subjective health. Process of family business succession may effect health. RESULTS might be applicable to other structurally similar agriculture regions and to craft sector. They promote individual confrontation with and social debate on a positive image of old age and aging. © Georg Thieme Verlag KG Stuttgart · New York.

  13. Design of the Chicago Health and Aging Project (CHAP).

    PubMed

    Bienias, Julia L; Beckett, Laurel A; Bennett, David A; Wilson, Robert S; Evans, Denis A

    2003-10-01

    The design of the Chicago Health and Aging Project (CHAP) is described. CHAP is a longitudinal population study of common chronic health problems of older persons, especially of risk factors for incident Alzheimer's disease, in a biracial neighborhood of the south side of Chicago. Special attention is given to three unusual design features of the study. One feature is that clinical evaluation for Alzheimer's disease is confined to a stratified random sample of all participants. This feature results in substantial cost savings and substantially less bias than screening approaches but has the disadvantages of adding analytic complexity and requiring the use of indirect means to identify a disease-free cohort for the development of incident Alzheimer's disease. The second unusual feature is efficiently combining in analyses the successive independent multiple samples that are drawn, one from each data collection cycle. The third unusual feature is entering successive age cohorts of community residents into the study as they attain 65 years of age. This has the advantages of enhancing direct investigation of the effect of age on the action of risk factors for Alzheimer's disease and direct examination of cohort effects. The interaction of these features is described, especially as they pertain to a study in which data are collected in successive waves. The results from these waves must be combined for effective analysis of the relation among risk factors and incident disease.

  14. Staff satisfaction and its components in residential aged care.

    PubMed

    Chou, Shu-Chiung; Boldy, Duncan P; Lee, Andy H

    2002-06-01

    The purpose of this study was to assess the direction and magnitude of the effects among the components of staff satisfaction in residential aged care and to examine whether the relationships among satisfaction components vary according to facility type (i.e. nursing homes and hostels). A hostel is a low care facility in which residents are more independent, have a lower level of care needs, and receive personal but not nursing care. A cross-sectional survey design was adopted to collect the required information, and a stratified random sampling approach was utilized to select facilities. Structural equation modeling was used to examine relationships among satisfaction components. Seventy residential aged care facilities in Western Australia. The sample includes 610 nursing home and 373 hostel care staff. The relationships among satisfaction components are different for nursing home and hostel staff. Professional support is found to have a strong and positive effect on all other aspects of staff satisfaction. The findings lead to an improved understanding of the interrelationship among staff satisfaction components, which has important implications through enhancing professional support. This needs to be recognized and emphasized by managers, care providers, and policy makers so as to maintain stable personnel and continuity of care.

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

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  16. Stratified mixing by microorganisms

    NASA Astrophysics Data System (ADS)

    Wagner, Gregory; Young, William; Lauga, Eric

    2013-11-01

    Vertical mixing is of fundamental significance to the general circulation, climate, and life in the ocean. In this work we consider whether organisms swimming at low Reynolds numbers might collectively contribute substantially to vertical mixing. Scaling analysis indicates that the mixing efficiency η, or the ratio between the rate of potential energy conversion and total work done on the fluid, should scale with η ~(a / l) 3 as a / l --> 0 , where a is the size of the organism and l = (νκ /N2)1/4 is an intrinsic length scale of a stratified fluid with kinematic viscosity ν, tracer diffusivity κ, and buoyancy frequency N2. A regularized singularity model demonstrates this scaling, indicating that in this same limit η ~ 1.2 (a / l) 3 for vertical swimming and η ~ 0.14 (a / l ) 3 for horizontal swimming. The model further predicts the absolute maximum mixing efficiency of an ensemble of randomly oriented organisms is around 6% and that the greatest mixing efficiencies in the ocean (in regions of strong salt-stratification) are closer to 0.1%, implying that the total contribution of microorganisms to vertical ocean mixing is negligible.

  17. Design and simulation of stratified probability digital receiver with application to the multipath communication

    NASA Technical Reports Server (NTRS)

    Deal, J. H.

    1975-01-01

    One approach to the problem of simplifying complex nonlinear filtering algorithms is through using stratified probability approximations where the continuous probability density functions of certain random variables are represented by discrete mass approximations. This technique is developed in this paper and used to simplify the filtering algorithms developed for the optimum receiver for signals corrupted by both additive and multiplicative noise.

  18. CONSISTENCY UNDER SAMPLING OF EXPONENTIAL RANDOM GRAPH MODELS.

    PubMed

    Shalizi, Cosma Rohilla; Rinaldo, Alessandro

    2013-04-01

    The growing availability of network data and of scientific interest in distributed systems has led to the rapid development of statistical models of network structure. Typically, however, these are models for the entire network, while the data consists only of a sampled sub-network. Parameters for the whole network, which is what is of interest, are estimated by applying the model to the sub-network. This assumes that the model is consistent under sampling , or, in terms of the theory of stochastic processes, that it defines a projective family. Focusing on the popular class of exponential random graph models (ERGMs), we show that this apparently trivial condition is in fact violated by many popular and scientifically appealing models, and that satisfying it drastically limits ERGM's expressive power. These results are actually special cases of more general results about exponential families of dependent random variables, which we also prove. Using such results, we offer easily checked conditions for the consistency of maximum likelihood estimation in ERGMs, and discuss some possible constructive responses.

  19. CONSISTENCY UNDER SAMPLING OF EXPONENTIAL RANDOM GRAPH MODELS

    PubMed Central

    Shalizi, Cosma Rohilla; Rinaldo, Alessandro

    2015-01-01

    The growing availability of network data and of scientific interest in distributed systems has led to the rapid development of statistical models of network structure. Typically, however, these are models for the entire network, while the data consists only of a sampled sub-network. Parameters for the whole network, which is what is of interest, are estimated by applying the model to the sub-network. This assumes that the model is consistent under sampling, or, in terms of the theory of stochastic processes, that it defines a projective family. Focusing on the popular class of exponential random graph models (ERGMs), we show that this apparently trivial condition is in fact violated by many popular and scientifically appealing models, and that satisfying it drastically limits ERGM’s expressive power. These results are actually special cases of more general results about exponential families of dependent random variables, which we also prove. Using such results, we offer easily checked conditions for the consistency of maximum likelihood estimation in ERGMs, and discuss some possible constructive responses. PMID:26166910

  20. Ar-40/Ar-39 ages and cosmic ray exposure ages of Apollo 14 samples.

    NASA Technical Reports Server (NTRS)

    Turner, G.; Huneke, J. C.; Podosek, F. A.; Wasserburg, G. J.

    1971-01-01

    We have used the Ar-40/Ar-39 dating technique on eight samples of Apollo 14 rocks (14053, 14310), breccia fragments (14321), and soil fragments (14001, 14167). The large basalt fragments give reasonable Ar-40/Ar-39 release patterns and yield well defined crystallization ages of 3.89-3.95 aeons. Correlation of the Ar-40/Ar-39 release patterns with Ar-39/Ar-37 patterns showed that the low temperature fractions with high radiogenic argon loss came from K-rich phases. A highly shocked sample and fragments included in the breccia yield complex release patterns with a low temperature peak. The total argon age of these fragments is 3.95 aeons. Cosmic ray exposure ages on these samples are obtained from the ratio of spallogenic Ar-38 to reactor induced Ar-37 and show a distinct grouping of low exposure ages of 26 m.y. correlated with Cone crater. Other samples have exposure ages of more than 260 m.y. and identify material with a more complex integrated cosmic age exposure history.

  1. Stratified flows in complex terrain

    NASA Astrophysics Data System (ADS)

    Retallack, Charles

    The focus of this dissertation is the study of stratified atmospheric flows in the presence of complex terrain. Two large-scale field study campaigns were carried out, each with a focus on a specific archetypal terrain. Each field study involved the utilization of remote and in-situ atmospheric monitoring devices to collect experimental data. The first of the two field studies focused on pollution transport mechanisms near an escarpment. The analysis aimed to determine the combined effect of the escarpment and ambient density stratification on the flow and aerosol pollution transport. It was found that under specific atmospheric conditions, the escarpment prompted the channeling, down-mixing, and trapping of aerosol pollutant plumes. The objective of the second field campaign was the study of stratified flows in a mountain valley. Analysis revealed that buoyancy driven katabatic currents originating on the surrounding valley slopes created a scenario in which a down-slope gravity current transitioned into an intrusive gravity current. The intrusive gravity current propagated near the interface of a density stratified lower ambient layer and a non-stratified upper ambient layer. A combination of shallow water theory and energy arguments is used to produce a model for the propagation of a gravity current moving along the interface of a homogeneous ambient layer and a linearly stratified layer. It is found that the gravity current propagating entirely within the homogeneous layer travels at the greatest speed. As the relative density of the gravity current is increased, the gravity current begins to slump below the interface of the two layers and the propagation speed decreases.

  2. Cost-effectiveness of risk stratified followup after urethral reconstruction: a decision analysis.

    PubMed

    Belsante, Michael J; Zhao, Lee C; Hudak, Steven J; Lotan, Yair; Morey, Allen F

    2013-10-01

    We propose a novel risk stratified followup protocol for use after urethroplasty and explore potential cost savings. Decision analysis was performed comparing a symptom based, risk stratified protocol for patients undergoing excision and primary anastomosis urethroplasty vs a standard regimen of close followup for urethroplasty. Model assumptions included that excision and primary anastomosis has a 94% success rate, 11% of patients with successful urethroplasty had persistent lower urinary tract symptoms requiring cystoscopic evaluation, patients in whom treatment failed undergo urethrotomy and patients with recurrence on symptom based surveillance have a delayed diagnosis requiring suprapubic tube drainage. The Nationwide Inpatient Sample from 2010 was queried to identify the number of urethroplasties performed per year in the United States. Costs were obtained based on Medicare reimbursement rates. The 5-year cost of a symptom based, risk stratified followup protocol is $430 per patient vs $2,827 per patient using standard close followup practice. An estimated 7,761 urethroplasties were performed in the United States in 2010. Assuming that 60% were excision and primary anastomosis, and with more than 5 years of followup, the risk stratified protocol was projected to yield an estimated savings of $11,165,130. Sensitivity analysis showed that the symptom based, risk stratified followup protocol was far more cost-effective than standard close followup in all settings. Less than 1% of patients would be expected to have an asymptomatic recurrence using the risk stratified followup protocol. A risk stratified, symptom based approach to urethroplasty followup would produce a significant reduction in health care costs while decreasing unnecessary followup visits, invasive testing and radiation exposure. Copyright © 2013 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  3. The Malleability of Spatial Ability under Treatment of a FIRST LEGO League-Based Robotics Simulation

    ERIC Educational Resources Information Center

    Coxon, Steve V.

    2012-01-01

    A stratified random sample of volunteer participants (N = 75) aged 9 to 14 was drawn from 16 public school districts' gifted programs, including as many females (n = 28) and children from groups traditionally underrepresented in gifted programs (n = 18) as available. Participants were randomly divided into an experimental (n = 38) and a control…

  4. Acceptance of living liver donation among medical students: A multicenter stratified study from Spain

    PubMed Central

    Ríos, Antonio; López-Navas, Ana Isabel; López-López, Ana Isabel; Gómez, Francisco Javier; Iriarte, Jorge; Herruzo, Rafael; Blanco, Gerardo; Llorca, Francisco Javier; Asunsolo, Angel; Sánchez-Gallegos, Pilar; Gutiérrez, Pedro Ramón; Fernández, Ana; de Jesús, María Teresa; Martínez-Alarcón, Laura; Lana, Alberto; Fuentes, Lorena; Hernández, Juan Ramón; Virseda, Julio; Yelamos, José; Bondía, José Antonio; Hernández, Antonio Miguel; Ayala, Marco Antonio; Ramírez, Pablo; Parrilla, Pascual

    2016-01-01

    AIM: To analyze the attitude of Spanish medical students toward living liver donation (LLD) and to establish which factors have an influence on this attitude. METHODS: Study type: A sociological, interdisciplinary, multicenter and observational study. Study population: Medical students enrolled in Spain (n = 34000) in the university academic year 2010-2011. Sample size: A sample of 9598 students stratified by geographical area and academic year. Instrument used to measure attitude: A validated questionnaire (PCID-DVH RIOS) was self-administered and completed anonymously. Data collection procedure: Randomly selected medical schools. The questionnaire was applied to each academic year at compulsory sessions. Statistical analysis: Student´s t test, χ2 test and logistic regression analysis. RESULTS: The completion rate was 95.7% (n = 9275). 89% (n = 8258) were in favor of related LLD, and 32% (n = 2937) supported unrelated LLD. The following variables were associated with having a more favorable attitude: (1) age (P = 0.008); (2) sex (P < 0.001); (3) academic year (P < 0.001); (4) geographical area (P = 0.013); (5) believing in the possibility of needing a transplant oneself in the future (P < 0.001); (6) attitude toward deceased donation (P < 0.001); (7) attitude toward living kidney donation (P < 0.001); (8) acceptance of a donated liver segment from a family member if one were needed (P < 0.001); (9) having discussed the subject with one's family (P < 0.001) and friends (P < 0.001); (10) a partner's opinion about the subject (P < 0.001); (11) carrying out activities of an altruistic nature; and (12) fear of the possible mutilation of the body after donation (P < 0.001). CONCLUSION: Spanish medical students have a favorable attitude toward LLD. PMID:27433093

  5. PROX1 is a novel pathway-specific prognostic biomarker for high-grade astrocytomas; results from independent glioblastoma cohorts stratified by age and IDH mutation status

    PubMed Central

    Edqvist, Per-Henrik D.; Hägerstrand, Daniel; Carlson, Joseph; Lysiak, Malgorzata; Henriksson, Roger; Pontén, Fredrik; Rosell, Johan; Söderkvist, Peter; Stupp, Roger; Tchougounova, Elena; Nistér, Monica; Malmström, Annika; Smits, Anja

    2016-01-01

    PROX1 is a transcription factor with an essential role in embryonic development and determination of cell fate. In addition, PROX1 has been ascribed suppressive as well as oncogenic roles in several human cancers, including brain tumors. In this study we explored the correlation between PROX1 expression and patient survival in high-grade astrocytomas. For this purpose, we analyzed protein expression in tissue microarrays of tumor samples stratified by patient age and IDH mutation status. We initially screened 86 unselected high-grade astrocytomas, followed by 174 IDH1-R132H1 immunonegative glioblastomas derived from patients aged 60 years and older enrolled in the Nordic phase III trial of elderly patients with newly diagnosed glioblastoma. Representing the younger population of glioblastomas, we studied 80 IDH-wildtype glioblastomas from patients aged 18-60 years. There was no correlation between PROX1 protein and survival for patients with primary glioblastomas included in these cohorts. In contrast, high expression of PROX1 protein predicted shorter survival in the group of patients with IDH-mutant anaplastic astrocytomas and secondary glioblastomas. The prognostic impact of PROX1 in IDH-mutant 1p19q non-codeleted high-grade astrocytomas, as well as the negative findings in primary glioblastomas, was corroborated by gene expression data extracted from the Cancer Genome Atlas. We conclude that PROX1 is a new prognostic biomarker for 1p19q non-codeleted high-grade astrocytomas that have progressed from pre-existing low-grade tumors and harbor IDH mutations. PMID:27626492

  6. Stratified Charge Engines

    DOT National Transportation Integrated Search

    1976-01-01

    This report reviews stratified charge concepts and engines, with emphasis on the important issues of exhaust emissions, fuel economy, and performance. Divided and open chamber designs are discussed. Potential improvements in exhaust emissions and fue...

  7. Plasma Carotenoids, Tocopherols, and Retinol in the Age-Stratified (35-74 Years) General Population: A Cross-Sectional Study in Six European Countries.

    PubMed

    Stuetz, Wolfgang; Weber, Daniela; Dollé, Martijn E T; Jansen, Eugène; Grubeck-Loebenstein, Beatrix; Fiegl, Simone; Toussaint, Olivier; Bernhardt, Juergen; Gonos, Efstathios S; Franceschi, Claudio; Sikora, Ewa; Moreno-Villanueva, María; Breusing, Nicolle; Grune, Tilman; Bürkle, Alexander

    2016-09-30

    Blood micronutrient status may change with age. We analyzed plasma carotenoids, α-/γ-tocopherol, and retinol and their associations with age, demographic characteristics, and dietary habits (assessed by a short food frequency questionnaire) in a cross-sectional study of 2118 women and men (age-stratified from 35 to 74 years) of the general population from six European countries. Higher age was associated with lower lycopene and α-/β-carotene and higher β-cryptoxanthin, lutein, zeaxanthin, α-/γ-tocopherol, and retinol levels. Significant correlations with age were observed for lycopene ( r = -0.248), α-tocopherol ( r = 0.208), α-carotene ( r = -0.112), and β-cryptoxanthin ( r = 0.125; all p < 0.001). Age was inversely associated with lycopene (-6.5% per five-year age increase) and this association remained in the multiple regression model with the significant predictors (covariables) being country, season, cholesterol, gender, smoking status, body mass index (BMI (kg/m²)), and dietary habits. The positive association of α-tocopherol with age remained when all covariates including cholesterol and use of vitamin supplements were included (1.7% vs. 2.4% per five-year age increase). The association of higher β-cryptoxanthin with higher age was no longer statistically significant after adjustment for fruit consumption, whereas the inverse association of α-carotene with age remained in the fully adjusted multivariable model (-4.8% vs. -3.8% per five-year age increase). We conclude from our study that age is an independent predictor of plasma lycopene, α-tocopherol, and α-carotene.

  8. Using maximum entropy modeling for optimal selection of sampling sites for monitoring networks

    USGS Publications Warehouse

    Stohlgren, Thomas J.; Kumar, Sunil; Barnett, David T.; Evangelista, Paul H.

    2011-01-01

    Environmental monitoring programs must efficiently describe state shifts. We propose using maximum entropy modeling to select dissimilar sampling sites to capture environmental variability at low cost, and demonstrate a specific application: sample site selection for the Central Plains domain (453,490 km2) of the National Ecological Observatory Network (NEON). We relied on four environmental factors: mean annual temperature and precipitation, elevation, and vegetation type. A “sample site” was defined as a 20 km × 20 km area (equal to NEON’s airborne observation platform [AOP] footprint), within which each 1 km2 cell was evaluated for each environmental factor. After each model run, the most environmentally dissimilar site was selected from all potential sample sites. The iterative selection of eight sites captured approximately 80% of the environmental envelope of the domain, an improvement over stratified random sampling and simple random designs for sample site selection. This approach can be widely used for cost-efficient selection of survey and monitoring sites.

  9. LOD score exclusion analyses for candidate genes using random population samples.

    PubMed

    Deng, H W; Li, J; Recker, R R

    2001-05-01

    While extensive analyses have been conducted to test for, no formal analyses have been conducted to test against, the importance of candidate genes with random population samples. We develop a LOD score approach for exclusion analyses of candidate genes with random population samples. Under this approach, specific genetic effects and inheritance models at candidate genes can be analysed and if a LOD score is < or = - 2.0, the locus can be excluded from having an effect larger than that specified. Computer simulations show that, with sample sizes often employed in association studies, this approach has high power to exclude a gene from having moderate genetic effects. In contrast to regular association analyses, population admixture will not affect the robustness of our analyses; in fact, it renders our analyses more conservative and thus any significant exclusion result is robust. Our exclusion analysis complements association analysis for candidate genes in random population samples and is parallel to the exclusion mapping analyses that may be conducted in linkage analyses with pedigrees or relative pairs. The usefulness of the approach is demonstrated by an application to test the importance of vitamin D receptor and estrogen receptor genes underlying the differential risk to osteoporotic fractures.

  10. Monitoring and identification of spatiotemporal landscape changes in multiple remote sensing images by using a stratified conditional Latin hypercube sampling approach and geostatistical simulation.

    PubMed

    Lin, Yu-Pin; Chu, Hone-Jay; Huang, Yu-Long; Tang, Chia-Hsi; Rouhani, Shahrokh

    2011-06-01

    This study develops a stratified conditional Latin hypercube sampling (scLHS) approach for multiple, remotely sensed, normalized difference vegetation index (NDVI) images. The objective is to sample, monitor, and delineate spatiotemporal landscape changes, including spatial heterogeneity and variability, in a given area. The scLHS approach, which is based on the variance quadtree technique (VQT) and the conditional Latin hypercube sampling (cLHS) method, selects samples in order to delineate landscape changes from multiple NDVI images. The images are then mapped for calibration and validation by using sequential Gaussian simulation (SGS) with the scLHS selected samples. Spatial statistical results indicate that in terms of their statistical distribution, spatial distribution, and spatial variation, the statistics and variograms of the scLHS samples resemble those of multiple NDVI images more closely than those of cLHS and VQT samples. Moreover, the accuracy of simulated NDVI images based on SGS with scLHS samples is significantly better than that of simulated NDVI images based on SGS with cLHS samples and VQT samples, respectively. However, the proposed approach efficiently monitors the spatial characteristics of landscape changes, including the statistics, spatial variability, and heterogeneity of NDVI images. In addition, SGS with the scLHS samples effectively reproduces spatial patterns and landscape changes in multiple NDVI images.

  11. On the importance of incorporating sampling weights in ...

    EPA Pesticide Factsheets

    Occupancy models are used extensively to assess wildlife-habitat associations and to predict species distributions across large geographic regions. Occupancy models were developed as a tool to properly account for imperfect detection of a species. Current guidelines on survey design requirements for occupancy models focus on the number of sample units and the pattern of revisits to a sample unit within a season. We focus on the sampling design or how the sample units are selected in geographic space (e.g., stratified, simple random, unequal probability, etc). In a probability design, each sample unit has a sample weight which quantifies the number of sample units it represents in the finite (oftentimes areal) sampling frame. We demonstrate the importance of including sampling weights in occupancy model estimation when the design is not a simple random sample or equal probability design. We assume a finite areal sampling frame as proposed for a national bat monitoring program. We compare several unequal and equal probability designs and varying sampling intensity within a simulation study. We found the traditional single season occupancy model produced biased estimates of occupancy and lower confidence interval coverage rates compared to occupancy models that accounted for the sampling design. We also discuss how our findings inform the analyses proposed for the nascent North American Bat Monitoring Program and other collaborative synthesis efforts that propose h

  12. Generating Random Samples of a Given Size Using Social Security Numbers.

    ERIC Educational Resources Information Center

    Erickson, Richard C.; Brauchle, Paul E.

    1984-01-01

    The purposes of this article are (1) to present a method by which social security numbers may be used to draw cluster samples of a predetermined size and (2) to describe procedures used to validate this method of drawing random samples. (JOW)

  13. Random On-Board Pixel Sampling (ROPS) X-Ray Camera

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Zhehui; Iaroshenko, O.; Li, S.

    Recent advances in compressed sensing theory and algorithms offer new possibilities for high-speed X-ray camera design. In many CMOS cameras, each pixel has an independent on-board circuit that includes an amplifier, noise rejection, signal shaper, an analog-to-digital converter (ADC), and optional in-pixel storage. When X-ray images are sparse, i.e., when one of the following cases is true: (a.) The number of pixels with true X-ray hits is much smaller than the total number of pixels; (b.) The X-ray information is redundant; or (c.) Some prior knowledge about the X-ray images exists, sparse sampling may be allowed. Here we first illustratemore » the feasibility of random on-board pixel sampling (ROPS) using an existing set of X-ray images, followed by a discussion about signal to noise as a function of pixel size. Next, we describe a possible circuit architecture to achieve random pixel access and in-pixel storage. The combination of a multilayer architecture, sparse on-chip sampling, and computational image techniques, is expected to facilitate the development and applications of high-speed X-ray camera technology.« less

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

    PubMed

    Bergh, Daniel

    2015-01-01

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

  15. Large-scale anisotropy in stably stratified rotating flows

    DOE PAGES

    Marino, R.; Mininni, P. D.; Rosenberg, D. L.; ...

    2014-08-28

    We present results from direct numerical simulations of the Boussinesq equations in the presence of rotation and/or stratification, both in the vertical direction. The runs are forced isotropically and randomly at small scales and have spatial resolutions of up tomore » $1024^3$ grid points and Reynolds numbers of $$\\approx 1000$$. We first show that solutions with negative energy flux and inverse cascades develop in rotating turbulence, whether or not stratification is present. However, the purely stratified case is characterized instead by an early-time, highly anisotropic transfer to large scales with almost zero net isotropic energy flux. This is consistent with previous studies that observed the development of vertically sheared horizontal winds, although only at substantially later times. However, and unlike previous works, when sufficient scale separation is allowed between the forcing scale and the domain size, the total energy displays a perpendicular (horizontal) spectrum with power law behavior compatible with $$\\sim k_\\perp^{-5/3}$$, including in the absence of rotation. In this latter purely stratified case, such a spectrum is the result of a direct cascade of the energy contained in the large-scale horizontal wind, as is evidenced by a strong positive flux of energy in the parallel direction at all scales including the largest resolved scales.« less

  16. Presence of psychoactive substances in oral fluid from randomly selected drivers in Denmark.

    PubMed

    Simonsen, K Wiese; Steentoft, A; Hels, T; Bernhoft, I M; Rasmussen, B S; Linnet, K

    2012-09-10

    This roadside study is the Danish part of the EU-project DRUID (Driving under the Influence of Drugs, Alcohol, and Medicines) and included three representative regions in Denmark. Oral fluid samples (n=3002) were collected randomly from drivers using a sampling scheme stratified by time, season, and road type. The oral fluid samples were screened for 29 illegal and legal psychoactive substances and metabolites as well as ethanol. Fourteen (0.5%) drivers were positive for ethanol (alone or in combination with drugs) at concentrations above 0.53g/l, which is the Danish legal limit. The percentage of drivers positive for medicinal drugs above the Danish legal concentration limit was 0.4%; while, 0.3% of the drivers tested positive for one or more illicit drug at concentrations exceeding the Danish legal limit. Tetrahydrocannabinol, cocaine, and amphetamine were the most frequent illicit drugs detected above the limit of quantitation (LOQ); while, codeine, tramadol, zopiclone, and benzodiazepines were the most frequent legal drugs. Middle aged men (median age 47.5 years) dominated the drunk driving group, while the drivers positive for illegal drugs consisted mainly of young men (median age 26 years). Middle aged women (median age 44.5 years) often tested positive for benzodiazepines at concentrations exceeding the legal limits. Interestingly, 0.6% of drivers tested positive for tramadol, at concentrations above the DRUID cut off; although, tramadol is not included in the Danish list of narcotic drugs. It can be concluded that driving under the influence of drugs is as serious a road safety problem as drunk driving. Copyright © 2012. Published by Elsevier Ireland Ltd.

  17. Using ankle-brachial index to detect peripheral arterial disease: prevalence and associated risk factors in a random population sample.

    PubMed

    Carbayo, Julio A; Divisón, Juan A; Escribano, Julio; López-Abril, Juan; López de Coca, Enrique; Artigao, Luis M; Martínez, Esperanza; Sanchis, Carlos; Massó, Javier; Carrión, Lucinio

    2007-01-01

    The ankle-brachial index (ABI) is being used increasingly to diagnose peripheral arterial disease (PAD) that predicts cardiovascular morbidity and mortality. The aim of this study is to determine the prevalence of PAD and associated risk factors in a Spanish random population sample of age > or =40. PAD is defined as an ABI<0.9 in either leg. 784 participants of age > or =40 were randomly selected in a Spanish province. 55.4% of them were female. The prevalence of PAD in this sample was 10.5% (95% confidence interval (CI) 8.4-12.8); 9.7% in females and 11.4% in males. In logistic regression analyses, adjusted for age and gender, smoking per 10 pack-years (odds ratio (OR) 1.40, 95% CI 1.23-1.58), hypertension (OR 1.85, 95% CI 1.05-3.28), hypercholesterolemia (OR 1.76, 95% CI 1.04-2.98), and diabetes (OR 1.80, 95% CI 1.04-3.11) were positively associated with prevalent PAD. More than 91% of persons with PAD had one or more cardiovascular disease risk factors. We conclude that in our study hypertension, hypercholesterolemia, diabetes mellitus and smoking are associated with PAD. The majority of individuals with PAD had at least one important cardiovascular risk factor advanced enough to be considered eligible for an aggressive treatment.

  18. Cross-Age Tutoring: A Strategy for Increasing Reading Achievement and Improving Self-Concept for Elementary School Children.

    ERIC Educational Resources Information Center

    Wood, Edwin Leon

    This study attempted to determine the effects of a twice-weekly, four-month-long, cross-age tutoring program on children's reading achievement levels and self-concepts. A total of 240 students, stratified by grade and sex, were randomly assigned to four experimental groups. Within each group, students were matched by grade: grade four with grade…

  19. Cluster-Randomized Trial to Increase Hepatitis B Testing among Koreans in Los Angeles

    PubMed Central

    Bastani, Roshan; Glenn, Beth A.; Maxwell, Annette E.; Jo, Angela M.; Herrmann, Alison K.; Crespi, Catherine M.; Wong, Weng K.; Chang, L. Cindy; Stewart, Susan L.; Nguyen, Tung T.; Chen, Moon S.; Taylor, Victoria M.

    2015-01-01

    Background In the United States, Korean immigrants experience a disproportionately high burden of chronic hepatitis B (HBV) viral infection and associated liver cancer compared to the general population. However, despite clear clinical guidelines, HBV serologic testing among Koreans remains persistently sub-optimal. Methods We conducted a cluster-randomized trial to evaluate a church-based small group intervention to improve HBV testing among Koreans in Los Angeles. Fifty-two Korean churches, stratified by size (small, medium, large) and location (Koreatown versus other), were randomized to intervention or control conditions. Intervention church participants attended a single-session small-group discussion on liver cancer and HBV testing and control church participants attended a similar session on physical activity and nutrition. Outcome data consisted of self-reported HBV testing obtained via 6-month telephone follow-up interviews. Results We recruited 1123 individuals, 18-64 years of age, across the 52 churches. Ninety-two percent of the sample attended the assigned intervention session and 86% completed the 6-month follow-up. Sample characteristics included: mean age 46 years, 65% female, 97% born in Korea, 69% completed some college, and 43% insured. In an intent-to-treat analysis, the intervention produced a statistically significant effect (OR = 4.9, p < .001), with 19% of intervention and 6% of control group participants reporting a HBV test. Conclusion Our intervention was successful in achieving a large and robust effect in a population at high risk of HBV infection and sequelae. Impact The intervention was fairly resource efficient and thus has high potential for replication in other high-risk Asian groups. PMID:26104909

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

    PubMed

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

    2017-12-01

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

  1. Cognitive function and dementia in six areas of England and Wales: the distribution of MMSE and prevalence of GMS organicity level in the MRC CFA Study. The Medical Research Council Cognitive Function and Ageing Study (MRC CFAS).

    PubMed

    1998-03-01

    This two-stage prevalence survey involved geographically delimited areas, four urban (Liverpool, Newcastle, Nottingham and Oxford) and two rural (Cambridgeshire and Gwynedd), including institutions. Stratified random population samples of people in their 65th year and above, from Family Health Service Authorities were studied. The sample was stratified (65-74 years and > or = 75) to provide equal numbers. In Liverpool equal numbers in 5 year age groups were taken. After an initial screening interview, approximately 20% were selected on the basis of age, AGECAT organicity confidence level and MMSE score to proceed to a detailed assessment interview from which the full AGECAT organicity confidence level could be derived. Major influences on MMSE were confirmed as age, sex, social class and educational level. Estimates of prevalence of AGECAT O3 and above for each centre and the entire sample according to age are given, based on 1991 Census population structure, and suggest that around half a million (543,400) people in England and Wales would be defined as case level by this method. The five centres employing the same methodology showed no heterogeneity in prevalence. Prevalence of cognitive impairment and dementia appear not to vary widely across the centres examined in this study, which provides stable estimates by age and sex for AGECAT O3 and above, and norms for MMSE. Using these estimates as an indication of the size of the population affected, around 550,000 individuals in England and Wales would be expected to be suffering from dementia of mild or greater severity.

  2. The use of oral sucrose for procedural pain relief in infants up to six months of age: a randomized controlled trial.

    PubMed

    Wilson, Sally; Bremner, Alexandra P; Mathews, Judy; Pearson, Diane

    2013-12-01

    The aim of this study was to evaluate the effectiveness of oral sucrose in decreasing pain during minor procedures in infants of 1-6 months corrected age. A blinded randomized controlled trial with infants aged 4-26 weeks who underwent venipuncture, heel lance or intravenous cannulation were stratified by corrected age into > 4-12 weeks and > 12-26 weeks. They received 2 mL of either 25% sucrose or sterile water orally 2 minutes before the painful procedure. Nonnutritional sucking and parental comfort, provided in adherence to hospital guidelines, were recorded. Pain behavior was recorded using a validated 10 point scale at baseline, during and following the procedure. Data collectors were blinded to the intervention. A total of 21 and 20 infants received sucrose and water, respectively, in the > 4-12-week age group, and 21 and 22, respectively, in the > 12-26-week age group. No statistical differences were found in pain scores between treatment and control groups at any data collection points in either age group. Infants aged > 4-12 weeks who did nonnutritional sucking showed statistically significantly lower median pain scores at 1, 2, and 3 minutes after the procedure than those who did not suck. Infants aged > 4-26 weeks exhibited pain behavior scores that indicated moderate to large pain during painful procedures; however, there was insufficient evidence to show that 2 mL 25% sucrose had a statistically significant effect in decreasing pain. Infants should be offered nonnutritional sucking in compliance with the Baby Friendly Health Initiative during painful procedures. Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.

  3. Insulin resistance index (HOMA-IR) levels in a general adult population: curves percentile by gender and age. The EPIRCE study.

    PubMed

    Gayoso-Diz, Pilar; Otero-Gonzalez, Alfonso; Rodriguez-Alvarez, María Xosé; Gude, Francisco; Cadarso-Suarez, Carmen; García, Fernando; De Francisco, Angel

    2011-10-01

    To describe the distribution of HOMA-IR levels in a general nondiabetic population and its relationships with metabolic and lifestyles characteristics. Cross-sectional study. Data from 2246 nondiabetic adults in a random Spanish population sample, stratified by age and gender, were analyzed. Assessments included a structured interview, physical examination, and blood sampling. Generalized additive models (GAMs) were used to assess the effect of lifestyle habits and clinical and demographic measurements on HOMA-IR. Multivariate GAMs and quantile regression analyses of HOMA-IR were carried out separately in men and women. This study shows refined estimations of HOMA-IR levels by age, body mass index, and waist circumference in men and women. HOMA-IR levels were higher in men (2.06) than women (1.95) (P=0.047). In women, but not men, HOMA-IR and age showed a significant nonlinear association (P=0.006), with increased levels above fifty years of age. We estimated HOMA-IR curves percentile in men and women. Age- and gender-adjusted HOMA-IR levels are reported in a representative Spanish adult non-diabetic population. There are gender-specific differences, with increased levels in women over fifty years of age that may be related with changes in body fat distribution after menopause. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

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

    PubMed

    Williamson, Graham R

    2003-11-01

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

  5. Improving depression and enhancing resilience in family dementia caregivers: a pilot randomized placebo-controlled trial of escitalopram.

    PubMed

    Lavretsky, Helen; Siddarth, Prabha; Irwin, Michael R

    2010-02-01

    This study examined the potential of an antidepressant drug, escitalopram, to improve depression, resilience to stress, and quality of life in family dementia caregivers in a randomized placebo-controlled double-blinded trial. Forty family caregivers (43-91 years of age, 25 children and 15 spouses; 26 women) who were taking care of their relatives with Alzheimer disease were randomized to receive either escitalopram 10 mg/day or placebo for 12 weeks. Severity of depression, resilience, burden, distress, quality of life, and severity of care-recipient's cognitive and behavioral disturbances were assessed at baseline and over the course of the study. The Hamilton Depression Rating Scale scores at baseline ranged between 10 and 28. The groups were stratified by the diagnosis of major and minor depression. Most outcomes favored escitalopram over placebo. The severity of depression improved, and the remission rate was greater with the drug compared with placebo. Measures of anxiety, resilience, burden, and distress improved on escitalopram compared with placebo. Among caregivers, this small randomized controlled trial found that escitalopram use resulted in improvement in depression, resilience, burden and distress, and quality of life. Our results need to be confirmed in a larger sample.

  6. [Hepatitis B prevalence among women in child-bearing age in Shandong Province, China, 2014].

    PubMed

    Zhang, L; Liu, J Y; Lyu, J J; Yan, B Y; Feng, Y; Wu, W L; Song, L Z; Xu, A Q

    2017-06-06

    Objective: To know the prevalence of hepatitis B virus (HBV) among women in child-bearing age in Shandong Province, China, providing references to the improvement of HBV control strategy. Methods: The participants were randomly selected by two-stage sampling method from 12 counties which were representative for the whole province. Firstly two townships were selected from each county by probability proportional to size sampling (PPS) method. Then participants aged 1-4 years, 5-14 years, 15-29 years and 30-59 years were selected by stratified random sampling method. The women in child-bearing age (20-49 years) were involved in this study. Questionnaire survey and 5 ml blood collection were conducted among all participants. Blood samples were detected for hepatitis B surface antigen (HBsAg), antibody against HBsAg (anti-HBs) and antibody against hepatitis B core antigen (anti-HBc). Those who were positive for HBsAg were further detected for hepatitis e antigen (HBeAg), antibody against HBeAg (anti-HBe) and the load of HBV DNA. The basic information of the participants including age, gender, occupation, nationality and residence place were collected. The prevalence of HBV infection indicators after weight adjustment were calculated and compared between participants with different demographic characteristics. Results: A total of 1 151 women in child-bearing age were involved in this study. Twenty-seven participants were positive for HBsAg and the prevalence rate was 2.10% (95 % CI: 0.97%-3.23%). Five participants were positive for both HBsAg and HBeAg and the prevalence rate was 0.36% (95 % CI: 0-0.84%). There were 567 and 291 participants who were positive for anti-HBs and anti-HBc respectively and the corresponding prevalence rates were 47.72% (95 %CI: 41.68%-53.75%) and 24.40% (95 % CI: 18.50%-30.30%). The number of participants susceptible for HBV was 527 and the percentage of HBV susceptible women was 47.55% (95 % CI: 41.63%-53.47%). Conclusion: HBV infection among

  7. Sample Size Calculations for Micro-randomized Trials in mHealth

    PubMed Central

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

    2015-01-01

    The use and development of mobile interventions are experiencing rapid growth. In “just-in-time” mobile interventions, treatments are provided via a mobile device and they are intended to help an individual make healthy decisions “in the moment,” and thus have a proximal, near future impact. Currently the development of mobile interventions is proceeding at a much faster pace than that of associated data science methods. A first step toward developing data-based methods is to provide an experimental design for testing the proximal effects of these just-in-time treatments. In this paper, we propose a “micro-randomized” trial design for this purpose. In a micro-randomized trial, treatments are sequentially randomized throughout the conduct of the study, with the result that each participant may be randomized at the 100s or 1000s of occasions at which a treatment might be provided. Further, we develop a test statistic for assessing the proximal effect of a treatment as well as an associated sample size calculator. We conduct simulation evaluations of the sample size calculator in various settings. Rules of thumb that might be used in designing a micro-randomized trial are discussed. This work is motivated by our collaboration on the HeartSteps mobile application designed to increase physical activity. PMID:26707831

  8. Smoothing the redshift distributions of random samples for the baryon acoustic oscillations: applications to the SDSS-III BOSS DR12 and QPM mock samples

    NASA Astrophysics Data System (ADS)

    Wang, Shao-Jiang; Guo, Qi; Cai, Rong-Gen

    2017-12-01

    We investigate the impact of different redshift distributions of random samples on the baryon acoustic oscillations (BAO) measurements of D_V(z)r_d^fid/r_d from the two-point correlation functions of galaxies in the Data Release 12 of the Baryon Oscillation Spectroscopic Survey (BOSS). Big surveys, such as BOSS, usually assign redshifts to the random samples by randomly drawing values from the measured redshift distributions of the data, which would necessarily introduce fiducial signals of fluctuations into the random samples, weakening the signals of BAO, if the cosmic variance cannot be ignored. We propose a smooth function of redshift distribution that fits the data well to populate the random galaxy samples. The resulting cosmological parameters match the input parameters of the mock catalogue very well. The significance of BAO signals has been improved by 0.33σ for a low-redshift sample and by 0.03σ for a constant-stellar-mass sample, though the absolute values do not change significantly. Given the precision of the measurements of current cosmological parameters, it would be appreciated for the future improvements on the measurements of galaxy clustering.

  9. Direct Numerical Simulation of a Weakly Stratified Turbulent Wake

    NASA Technical Reports Server (NTRS)

    Redford, J. A.; Lund, T. S.; Coleman, Gary N.

    2014-01-01

    Direct numerical simulation (DNS) is used to investigate a time-dependent turbulent wake evolving in a stably stratified background. A large initial Froude number is chosen to allow the wake to become fully turbulent and axisymmetric before stratification affects the spreading rate of the mean defect. The uncertainty introduced by the finite sample size associated with gathering statistics from a simulation of a time-dependent flow is reduced, compared to earlier simulations of this flow. The DNS reveals the buoyancy-induced changes to the turbulence structure, as well as to the mean-defect history and the terms in the mean-momentum and turbulence-kinetic-energy budgets, that characterize the various states of this flow - namely the three-dimensional (essentially unstratified), non-equilibrium (or 'wake-collapse') and quasi-two-dimensional (or 'two-component') regimes observed elsewhere for wakes embedded in both weakly and strongly stratified backgrounds. The wake-collapse regime is not accompanied by transfer (or 'reconversion') of the potential energy of the turbulence to the kinetic energy of the turbulence, implying that this is not an essential feature of stratified-wake dynamics. The dependence upon Reynolds number of the duration of the wake-collapse period is demonstrated, and the effect of the details of the initial/near-field conditions of the wake on its subsequent development is examined.

  10. On the repeated measures designs and sample sizes for randomized controlled trials.

    PubMed

    Tango, Toshiro

    2016-04-01

    For the analysis of longitudinal or repeated measures data, generalized linear mixed-effects models provide a flexible and powerful tool to deal with heterogeneity among subject response profiles. However, the typical statistical design adopted in usual randomized controlled trials is an analysis of covariance type analysis using a pre-defined pair of "pre-post" data, in which pre-(baseline) data are used as a covariate for adjustment together with other covariates. Then, the major design issue is to calculate the sample size or the number of subjects allocated to each treatment group. In this paper, we propose a new repeated measures design and sample size calculations combined with generalized linear mixed-effects models that depend not only on the number of subjects but on the number of repeated measures before and after randomization per subject used for the analysis. The main advantages of the proposed design combined with the generalized linear mixed-effects models are (1) it can easily handle missing data by applying the likelihood-based ignorable analyses under the missing at random assumption and (2) it may lead to a reduction in sample size, compared with the simple pre-post design. The proposed designs and the sample size calculations are illustrated with real data arising from randomized controlled trials. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  11. Plasma Carotenoids, Tocopherols, and Retinol in the Age-Stratified (35–74 Years) General Population: A Cross-Sectional Study in Six European Countries

    PubMed Central

    Stuetz, Wolfgang; Weber, Daniela; Dollé, Martijn E. T.; Jansen, Eugène; Grubeck-Loebenstein, Beatrix; Fiegl, Simone; Toussaint, Olivier; Bernhardt, Juergen; Gonos, Efstathios S.; Franceschi, Claudio; Sikora, Ewa; Moreno-Villanueva, María; Breusing, Nicolle; Grune, Tilman; Bürkle, Alexander

    2016-01-01

    Blood micronutrient status may change with age. We analyzed plasma carotenoids, α-/γ-tocopherol, and retinol and their associations with age, demographic characteristics, and dietary habits (assessed by a short food frequency questionnaire) in a cross-sectional study of 2118 women and men (age-stratified from 35 to 74 years) of the general population from six European countries. Higher age was associated with lower lycopene and α-/β-carotene and higher β-cryptoxanthin, lutein, zeaxanthin, α-/γ-tocopherol, and retinol levels. Significant correlations with age were observed for lycopene (r = −0.248), α-tocopherol (r = 0.208), α-carotene (r = −0.112), and β-cryptoxanthin (r = 0.125; all p < 0.001). Age was inversely associated with lycopene (−6.5% per five-year age increase) and this association remained in the multiple regression model with the significant predictors (covariables) being country, season, cholesterol, gender, smoking status, body mass index (BMI (kg/m2)), and dietary habits. The positive association of α-tocopherol with age remained when all covariates including cholesterol and use of vitamin supplements were included (1.7% vs. 2.4% per five-year age increase). The association of higher β-cryptoxanthin with higher age was no longer statistically significant after adjustment for fruit consumption, whereas the inverse association of α-carotene with age remained in the fully adjusted multivariable model (−4.8% vs. −3.8% per five-year age increase). We conclude from our study that age is an independent predictor of plasma lycopene, α-tocopherol, and α-carotene. PMID:27706032

  12. A model-based 'varimax' sampling strategy for a heterogeneous population.

    PubMed

    Akram, Nuzhat A; Farooqi, Shakeel R

    2014-01-01

    Sampling strategies are planned to enhance the homogeneity of a sample, hence to minimize confounding errors. A sampling strategy was developed to minimize the variation within population groups. Karachi, the largest urban agglomeration in Pakistan, was used as a model population. Blood groups ABO and Rh factor were determined for 3000 unrelated individuals selected through simple random sampling. Among them five population groups, namely Balochi, Muhajir, Pathan, Punjabi and Sindhi, based on paternal ethnicity were identified. An index was designed to measure the proportion of admixture at parental and grandparental levels. Population models based on index score were proposed. For validation, 175 individuals selected through stratified random sampling were genotyped for the three STR loci CSF1PO, TPOX and TH01. ANOVA showed significant differences across the population groups for blood groups and STR loci distribution. Gene diversity was higher across the sub-population model than in the agglomerated population. At parental level gene diversities are significantly higher across No admixture models than Admixture models. At grandparental level the difference was not significant. A sub-population model with no admixture at parental level was justified for sampling the heterogeneous population of Karachi.

  13. The effect of surfactant on stratified and stratifying gas-liquid flows

    NASA Astrophysics Data System (ADS)

    Heiles, Baptiste; Zadrazil, Ivan; Matar, Omar

    2013-11-01

    We consider the dynamics of a stratified/stratifying gas-liquid flow in horizontal tubes. This flow regime is characterised by the thin liquid films that drain under gravity along the pipe interior, forming a pool at the bottom of the tube, and the formation of large-amplitude waves at the gas-liquid interface. This regime is also accompanied by the detachment of droplets from the interface and their entrainment into the gas phase. We carry out an experimental study involving axial- and radial-view photography of the flow, in the presence and absence of surfactant. We show that the effect of surfactant is to reduce significantly the average diameter of the entrained droplets, through a tip-streaming mechanism. We also highlight the influence of surfactant on the characteristics of the interfacial waves, and the pressure gradient that drives the flow. EPSRC Programme Grant EP/K003976/1.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  15. A binary logistic regression model with complex sampling design of unmet need for family planning among all women aged (15-49) in Ethiopia.

    PubMed

    Workie, Demeke Lakew; Zike, Dereje Tesfaye; Fenta, Haile Mekonnen; Mekonnen, Mulusew Admasu

    2017-09-01

    Unintended pregnancy related to unmet need is a worldwide problem that affects societies. The main objective of this study was to identify the prevalence and determinants of unmet need for family planning among women aged (15-49) in Ethiopia. The Performance Monitoring and Accountability2020/Ethiopia was conducted in April 2016 at round-4 from 7494 women with two-stage-stratified sampling. Bi-variable and multi-variable binary logistic regression model with complex sampling design was fitted. The prevalence of unmet-need for family planning was 16.2% in Ethiopia. Women between the age range of 15-24 years were 2.266 times more likely to have unmet need family planning compared to above 35 years. Women who were currently married were about 8 times more likely to have unmet need family planning compared to never married women. Women who had no under-five child were 0.125 times less likely to have unmet need family planning compared to those who had more than two-under-5. The key determinants of unmet need family planning in Ethiopia were residence, age, marital-status, education, household members, birth-events and number of under-5 children. Thus the Government of Ethiopia would take immediate steps to address the causes of high unmet need for family planning among women.

  16. Jet-front systems nearing strongly stratified region in differentially heated, rotating stratified annulus

    NASA Astrophysics Data System (ADS)

    Rolland, Joran; Achatz, Ulrich

    2017-04-01

    The differentially heated, rotating annulus configuration has been used for a long time as a model system of the earth troposphere. It can easily reproduce thermal wind and baroclinic waves in the laboratory. It has recently been shown numerically that provided the Rossby number, the rotation rate and the Brunt-Väisälä frequency were well chosen, this configuration also reproduces the spontaneous emission of gravity waves by jet front systems [1]. This offers a very practical configuration in which to study an important process of emission of atmospheric gravity waves. It has also been shown experimentally that this configuration can be modified in order to add the possibility for the emitted wave to reach a strongly stratified region [2]. It thus creates a system containing a model troposphere where gravity waves are spontaneously emitted and can propagate to a model stratosphere. For this matter a stratification was created using a salinity gradient in the experimental apparatus. Through double diffusion, this generates a strongly stratified layer in the middle of the flow (the model stratosphere) and two weakly stratified region in the top and bottom layers (the model troposphere). In this poster, we present simulations of this configuration displaying baroclinic waves in the top and bottom layers. We aim at creating jet front systems strong enough that gravity waves can be spontaneously emitted. This will thus offer the possibility of studying the wave characteristic and mechanisms in emission and propagation in details. References [1] S. Borchert, U. Achatz, M.D. Fruman, Spontaneous Gravity wave emission in the differentially heated annulus, J. Fluid Mech. 758, 287-311 (2014). [2] M. Vincze, I. Borcia, U. Harlander, P. Le Gal, Double-diffusive convection convection and baroclinic instability in a differentially heated and initially stratified rotating system: the barostrat instability, Fluid Dyn. Res. 48, 061414 (2016).

  17. Suicide and Ambient Temperature in East Asian Countries: A Time-Stratified Case-Crossover Analysis

    PubMed Central

    Kim, Yoonhee; Honda, Yasushi; Guo, Yue Leon; Chen, Bing-Yu; Woo, Jong-Min; Ebi, Kristie L.

    2015-01-01

    Background A limited number of studies suggest that ambient temperature contributes to suicide; these studies typically focus on a single nation and use temporally and spatially aggregated data. Objective We evaluated the association between ambient temperature and suicide in multiple cities in three East Asian countries. Methods A time-stratified case-crossover method was used to explore the relationship between temperature and suicide, adjusting for potential time-varying confounders and time-invariant individual characteristics. Sex- and age-specific associations of temperature with suicide were estimated, as were interactions between temperature and these variables. A random-effects meta-analysis was used to estimate country-specific pooled associations of temperature with suicide. Results An increase in temperature corresponding to half of the city-specific standard deviation was positively associated with suicide in most cities, although average suicide rates varied substantially. Pooled country-level effect estimates were 7.8% (95% CI: 5.0, 10.8%) for a 2.3°C increase in ambient temperature in Taiwan, 6.8% (95% CI: 5.4, 8.2%) for a 4.7°C increase in Korea, and 4.5% (95% CI: 3.3, 5.7%) for a 4.2°C increase in Japan. The association between temperature and suicide was significant even after adjusting for sunshine duration; the association between sunshine and suicide was not significant. The associations were greater among men than women in 12 of the 15 cities although not significantly so. There was little evidence of a consistent pattern of associations with age. In general, associations were strongest with temperature on the same day or the previous day, with little evidence of associations with temperature over longer lags (up to 5 days). Conclusions We estimated consistent positive associations between suicide and elevated ambient temperature in three East Asian countries, regardless of country, sex, and age. Citation Kim Y, Kim H, Honda Y, Guo YL

  18. Assessment of powder blend uniformity: Comparison of real-time NIR blend monitoring with stratified sampling in combination with HPLC and at-line NIR Chemical Imaging.

    PubMed

    Bakri, Barbara; Weimer, Marco; Hauck, Gerrit; Reich, Gabriele

    2015-11-01

    Scope of the study was (1) to develop a lean quantitative calibration for real-time near-infrared (NIR) blend monitoring, which meets the requirements in early development of pharmaceutical products and (2) to compare the prediction performance of this approach with the results obtained from stratified sampling using a sample thief in combination with off-line high pressure liquid chromatography (HPLC) and at-line near-infrared chemical imaging (NIRCI). Tablets were manufactured from powder blends and analyzed with NIRCI and HPLC to verify the real-time results. The model formulation contained 25% w/w naproxen as a cohesive active pharmaceutical ingredient (API), microcrystalline cellulose and croscarmellose sodium as cohesive excipients and free-flowing mannitol. Five in-line NIR calibration approaches, all using the spectra from the end of the blending process as reference for PLS modeling, were compared in terms of selectivity, precision, prediction accuracy and robustness. High selectivity could be achieved with a "reduced" approach i.e. API and time saving approach (35% reduction of API amount) based on six concentration levels of the API with three levels realized by three independent powder blends and the additional levels obtained by simply increasing the API concentration in these blends. Accuracy and robustness were further improved by combining this calibration set with a second independent data set comprising different excipient concentrations and reflecting different environmental conditions. The combined calibration model was used to monitor the blending process of independent batches. For this model formulation the target concentration of the API could be achieved within 3 min indicating a short blending time. The in-line NIR approach was verified by stratified sampling HPLC and NIRCI results. All three methods revealed comparable results regarding blend end point determination. Differences in both mean API concentration and RSD values could be

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

    NASA Astrophysics Data System (ADS)

    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

  20. Generalized and synthetic regression estimators for randomized branch sampling

    Treesearch

    David L. R. Affleck; Timothy G. Gregoire

    2015-01-01

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

  1. Absorption Peaks: α, β, γ and Their Covariance with Age and Hemoglobin in Human Blood Samples Using Photoacoustic Spectroscopy

    NASA Astrophysics Data System (ADS)

    González-Domínguez, J. L.; Hernández-Aguilar, C.; Domínguez-Pacheco, F. A.; Martínez-Ortiz, E.; Cruz-Orea, A.; Sánchez-Sinencio, F.

    2012-11-01

    This study reports the absorption peaks α, β, γ in the Soret band of photoacoustic (PA) signals and their covariance with age and hemoglobin in human blood samples through PA spectroscopy. Samples were taken randomly from a masculine population grouped in three categories according to age: infants, young adults, and senior adults. Samples were prepared with two drops of blood from a 0.5 mL insulin syringe with a needle gauge 31G over 5 mm circles of filter paper. It was observed that the PA signal, the amplitude as a function of the wavelength, has a behavior as that reported for human blood for the three absorption peaks α, β, γ. In particular, the ratio γ/ β is due to electronic transitions associated with charge-transfer interactions of iron orbitals with the ligand states. Through an evaluation of optical absorption peaks in blood samples and their covariance with age and hemoglobin concentration, a relationship was found for the ratio peaks γ/ β and γ/ α with such parameters. Specifically, a negative covariance in the Soret band of the ratio peaks γ/ β and γ/ α with respect to both age and hemoglobin was found. This showed a tendency in their behavior. Further experiments of different populations may corroborate these conclusions.

  2. The Relationship between School Achievement and Peer Harassment in Canadian Adolescents: The Importance of Mediating Factors

    ERIC Educational Resources Information Center

    Beran, Tanya N.; Lupart, Judy

    2009-01-01

    The relationship between school achievement and peer harassment was examined using individual and peer characteristics as mediating factors. The sample consisted of adolescents age 12-15 years (n = 4,111) drawn from the Canadian National Longitudinal Survey of Children and Youth, which is a stratified random sample of 22,831 households in Canada.…

  3. Sexual Sensation Seeking, Social Stress, and Coping Styles as Predictors of HIV/STD Risk Behaviors in Adolescents

    ERIC Educational Resources Information Center

    Teva, Inmaculada; Bermudez, Maria Paz; Buela-Casal, Gualberto

    2010-01-01

    The aim of this study was to assess whether coping styles, social stress, and sexual sensation seeking were predictors of HIV/STD risk behaviours in adolescents. A representative sample of 4,456 female and male Spanish high school students aged 13 to 18 years participated. A stratified random sampling procedure was used. Self-report questionnaires…

  4. Adjunctive Mitomycin C or Amniotic Membrane Transplantation for Ahmed Glaucoma Valve Implantation: A Randomized Clinical Trial.

    PubMed

    Yazdani, Shahin; Mahboobipour, Hassan; Pakravan, Mohammad; Doozandeh, Azadeh; Ghahari, Elham

    2016-05-01

    To determine whether adjunctive mitomycin C (MMC) or amniotic membrane transplantation (AMT) improve the outcomes of Ahmed glaucoma valve (AGV) implantation. This double-blind, stratified, 3-armed randomized clinical trial includes 75 eyes of 75 patients aged 7 to 75 years with refractory glaucoma. Eligible subjects underwent stratified block randomization; eyes were first stratified to surgery in the superior or inferior quadrants based on feasibility; in each subgroup, eyes were randomly assigned to the study arms using random blocks: conventional AGV implantation (group A, 25 eyes), AGV with MMC (group B, 25 eyes), and AGV with AMT (group C, 25 eyes). The 3 study groups were comparable regarding baseline characteristics and mean follow-up (P=0.288). A total of 68 patients including 23 eyes in group A, 25 eyes in group B, and 20 eyes group C completed the follow-up period and were analyzed. Intraocular pressure was lower in the MMC group only 3 weeks postoperatively (P=0.04) but comparable at other time intervals. Overall success rate was comparable in the 3 groups at 12 months (P=0.217). The number of eyes requiring medications (P=0.30), time to initiation of medications (P=0.13), and number of medications (P=0.22) were comparable. Hypertensive phase was slightly but insignificantly more common with standard surgery (82%) as compared with MMC-augmented (60%) and AMT-augmented (70%) procedures (P=0.23). Complications were comparable over 1 year (P=0.28). Although adjunctive MMC and AMT were safe during AGV implantation, they did not influence success rates or intraocular pressure outcomes. Complications, including hypertensive phase, were also comparable.

  5. Language Learning Motivation in China: Results of a Large-Scale Stratified Survey

    ERIC Educational Resources Information Center

    You, Chenjing; Dörnyei, Zoltán

    2016-01-01

    This article reports on the findings of a large-scale cross-sectional survey of the motivational disposition of English language learners in secondary schools and universities in China. The total sample involved over 10,000 students and was stratified according to geographical region and teaching contexts, selecting participants both from urban…

  6. Development and enrolee satisfaction with basic medical insurance in China: A systematic review and stratified cluster sampling survey.

    PubMed

    Jing, Limei; Chen, Ru; Jing, Lisa; Qiao, Yun; Lou, Jiquan; Xu, Jing; Wang, Junwei; Chen, Wen; Sun, Xiaoming

    2017-07-01

    Basic Medical Insurance (BMI) has changed remarkably over time in China because of health reforms that aim to achieve universal coverage and better health care with adequate efforts by increasing subsidies, reimbursement, and benefits. In this paper, we present the development of BMI, including financing and operation, with a systematic review. Meanwhile, Pudong New Area in Shanghai was chosen as a typical BMI sample for its coverage and management; a stratified cluster sampling survey together with an ordinary logistic regression model was used for the analysis. Enrolee satisfaction and the factors associated with enrolee satisfaction with BMI were analysed. We found that the reenrolling rate superficially improved the BMI coverage and nearly achieved universal coverage. However, BMI funds still faced dual contradictions of fund deficit and insured under compensation, and a long-term strategy is needed to realize the integration of BMI schemes with more homogeneous coverage and benefits. Moreover, Urban Resident Basic Medical Insurance participants reported a higher rate of dissatisfaction than other participants. The key predictors of the enrolees' satisfaction were awareness of the premium and compensation, affordability of out-of-pocket costs, and the proportion of reimbursement. These results highlight the importance that the Chinese government takes measures, such as strengthening BMI fund management, exploring mixed payment methods, and regulating sequential medical orders, to develop an integrated medical insurance system of universal coverage and vertical equity while simultaneously improving enrolee satisfaction. Copyright © 2017 John Wiley & Sons, Ltd.

  7. Analysis of Turbulent Combustion in Simplified Stratified Charge Conditions

    NASA Astrophysics Data System (ADS)

    Moriyoshi, Yasuo; Morikawa, Hideaki; Komatsu, Eiji

    The stratified charge combustion system has been widely studied due to the significant potentials for low fuel consumption rate and low exhaust gas emissions. The fuel-air mixture formation process in a direct-injection stratified charge engine is influenced by various parameters, such as atomization, evaporation, and in-cylinder gas motion at high temperature and high pressure conditions. It is difficult to observe the in-cylinder phenomena in such conditions and also challenging to analyze the following stratified charge combustion. Therefore, the combustion phenomena in simplified stratified charge conditions aiming to analyze the fundamental stratified charge combustion are examined. That is, an experimental apparatus which can control the mixture distribution and the gas motion at ignition timing was developed, and the effects of turbulence intensity, mixture concentration distribution, and mixture composition on stratified charge combustion were examined. As a result, the effects of fuel, charge stratification, and turbulence on combustion characteristics were clarified.

  8. Effects of Training Method and Gender on Learning 2D/3D Geometry

    ERIC Educational Resources Information Center

    Khairulanuar, Samsudin; Nazre, Abd Rashid; Jamilah, H.; Sairabanu, Omar Khan; Norasikin, Fabil

    2010-01-01

    This article reports the findings of an experimental study involving 36 primary school students (16 girls, 20 boys, Mean age = 9.5 years, age range: 8-10 years) in geometrical understanding of 2D and 3D objects. Students were assigned into two experimental groups and one control group based on a stratified random sampling procedure. The first…

  9. Men's Health Index: a pragmatic approach to stratifying and optimizing men's health.

    PubMed

    Tan, Hui Meng; Tan, Wei Phin; Wong, Jun Hoe; Ho, Christopher Chee Kong; Teo, Chin Hai; Ng, Chirk Jenn

    2014-11-01

    The proposed Men's Health Index (MHI) aims to provide a practical and systematic framework for comprehensively assessing and stratifying older men with the intention of optimising their health and functional status. A literature search was conducted using PubMed from 1980 to 2012. We specifically looked for instruments which: assess men's health, frailty and fitness; predict life expectancy, mortality and morbidities. The instruments were assessed by the researchers who then agreed on the tools to be included in the MHI. When there was disagreements, the researchers discussed and reached a consensus guided by the principle that the MHI could be used in the primary care setting targetting men aged 55-65 years. The instruments chosen include the Charlson's Combined Comorbidity-Age Index; the International Index of Erectile Function-5; the International Prostate Symptom Score; the Androgen Deficiency in Aging Male; the Survey of Health, Ageing and Retirement in Europe Frailty Instrument; the Sitting-Rising Test; the Senior Fitness Test; the Fitness Assessment Score; and the Depression Anxiety Stress Scale-21. A pilot test on eight men was carried out and showed that the men's health index is viable. The concept of assessing, stratifying, and optimizing men's health should be incorporated into routine health care, and this can be implemented by using the MHI. This index is particularly useful to primary care physicians who are in a strategic position to engage men at the peri-retirement age in a conversation about their life goals based on their current and predicted health status.

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

    PubMed

    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.

  11. DSM-5 field trials in the United States and Canada, Part I: study design, sampling strategy, implementation, and analytic approaches.

    PubMed

    Clarke, Diana E; Narrow, William E; Regier, Darrel A; Kuramoto, S Janet; Kupfer, David J; Kuhl, Emily A; Greiner, Lisa; Kraemer, Helena C

    2013-01-01

    This article discusses the design,sampling strategy, implementation,and data analytic processes of the DSM-5 Field Trials. The DSM-5 Field Trials were conducted by using a test-retest reliability design with a stratified sampling approach across six adult and four pediatric sites in the United States and one adult site in Canada. A stratified random sampling approach was used to enhance precision in the estimation of the reliability coefficients. A web-based research electronic data capture system was used for simultaneous data collection from patients and clinicians across sites and for centralized data management.Weighted descriptive analyses, intraclass kappa and intraclass correlation coefficients for stratified samples, and receiver operating curves were computed. The DSM-5 Field Trials capitalized on advances since DSM-III and DSM-IV in statistical measures of reliability (i.e., intraclass kappa for stratified samples) and other recently developed measures to determine confidence intervals around kappa estimates. Diagnostic interviews using DSM-5 criteria were conducted by 279 clinicians of varied disciplines who received training comparable to what would be available to any clinician after publication of DSM-5.Overall, 2,246 patients with various diagnoses and levels of comorbidity were enrolled,of which over 86% were seen for two diagnostic interviews. A range of reliability coefficients were observed for the categorical diagnoses and dimensional measures. Multisite field trials and training comparable to what would be available to any clinician after publication of DSM-5 provided “real-world” testing of DSM-5 proposed diagnoses.

  12. Randomized trial using gonadotropin-releasing hormone agonist triptorelin for the preservation of ovarian function during (neo)adjuvant chemotherapy for breast cancer.

    PubMed

    Munster, Pamela N; Moore, Amy P; Ismail-Khan, Roohi; Cox, Charles E; Lacevic, Mensura; Gross-King, Margaret; Xu, Ping; Carter, W Bradford; Minton, Susan E

    2012-02-10

    Chemotherapy-induced amenorrhea is a serious concern for women undergoing cancer therapy. This prospective randomized trial evaluated the use of gonadotropin-releasing hormone (GnRH) analog triptorelin to preserve ovarian function in women treated with chemotherapy for early-stage breast cancer. Premenopausal women age 44 years or younger were randomly assigned to receive either triptorelin or no triptorelin during (neo)adjuvant chemotherapy and were further stratified by age (< 35, 35 to 39, > 39 years), estrogen receptor status, and chemotherapy regimen. Objectives included the resumption of menses and serial monitoring of follicle-stimulating hormone (FSH) and inhibin A and B levels. Targeted for 124 patients with a planned 5-year follow-up, the trial was stopped for futility after 49 patients were enrolled (median age, 39 years; range, 21 to 43 years); 47 patients were treated according to assigned groups with four cycles of adriamycin plus cyclophosphamide alone or followed by four cycles of paclitaxel or six cycles of fluorouracil, epirubicin, and cyclophosphamide. Menstruation resumed in 19 (90%) of 21 patients in the control group and in 23 (88%) of 26 in the triptorelin group (P= .36). Menses returned after a median of 5.8 months (range, 1 to 19 months) after completion of chemotherapy in the triptorelin versus 5.0 months (range, 0 to 28 months) in the control arm (P= .58). Two patients (age 26 and 35 years at random assignment) in the control group had spontaneous pregnancies with term deliveries. FSH and inhibin B levels correlated with menstrual status. When stratified for age, estrogen receptor status, and treatment regimen, amenorrhea rates on triptorelin were comparable to those seen in the control group.

  13. Cluster-Randomized Trial to Increase Hepatitis B Testing among Koreans in Los Angeles.

    PubMed

    Bastani, Roshan; Glenn, Beth A; Maxwell, Annette E; Jo, Angela M; Herrmann, Alison K; Crespi, Catherine M; Wong, Weng K; Chang, L Cindy; Stewart, Susan L; Nguyen, Tung T; Chen, Moon S; Taylor, Victoria M

    2015-09-01

    In the United States, Korean immigrants experience a disproportionately high burden of chronic hepatitis B (HBV) viral infection and associated liver cancer compared with the general population. However, despite clear clinical guidelines, HBV serologic testing among Koreans remains persistently suboptimal. We conducted a cluster-randomized trial to evaluate a church-based small group intervention to improve HBV testing among Koreans in Los Angeles. Fifty-two Korean churches, stratified by size (small, medium, large) and location (Koreatown versus other), were randomized to intervention or control conditions. Intervention church participants attended a single-session small-group discussion on liver cancer and HBV testing, and control church participants attended a similar session on physical activity and nutrition. Outcome data consisted of self-reported HBV testing obtained via 6-month telephone follow-up interviews. We recruited 1,123 individuals, 18 to 64 years of age, across the 52 churches. Ninety-two percent of the sample attended the assigned intervention session and 86% completed the 6-month follow-up. Sample characteristics included were as follows: mean age 46 years, 65% female, 97% born in Korea, 69% completed some college, and 43% insured. In an intent-to-treat analysis, the intervention produced a statistically significant effect (OR = 4.9, P < 0.001), with 19% of intervention and 6% of control group participants reporting a HBV test. Our intervention was successful in achieving a large and robust effect in a population at high risk of HBV infection and sequelae. The intervention was fairly resource efficient and thus has high potential for replication in other high-risk Asian groups. ©2015 American Association for Cancer Research.

  14. The Stroop color-word test: influence of age, sex, and education; and normative data for a large sample across the adult age range.

    PubMed

    Van der Elst, Wim; Van Boxtel, Martin P J; Van Breukelen, Gerard J P; Jolles, Jelle

    2006-03-01

    The Stroop Color-Word Test was administered to 1,856 cognitively screened, healthy Dutch speaking participants aged 24 to 81 years. The effects of age, gender, and education on Stroop test performance were investigated to adequately stratify the normative data. The results showed that especially the speed-dependent Stroop scores (time to complete a subtest), rather than the accuracy measures (the errors made per Stroop sub-task), were profoundly affected by the demographic variables. In addition to the main effects of the demographic variables, an Age Low Level of Education interaction was found for the Error III and the Stroop Interference scores. This suggests that executive function, as measured by the Stroop test, declines with age and that the decline is more pronounced in people with a low level of education. This is consistent with the reserve hypothesis of brain aging (i.e., that education generates reserve capacity against the damaging effects of aging on brain functions). Normative Stroop data were established using both a regression-based and traditional approach, and the appropriateness of both methods for generating normative data is discussed.

  15. A simple and efficient alternative to implementing systematic random sampling in stereological designs without a motorized microscope stage.

    PubMed

    Melvin, Neal R; Poda, Daniel; Sutherland, Robert J

    2007-10-01

    When properly applied, stereology is a very robust and efficient method to quantify a variety of parameters from biological material. A common sampling strategy in stereology is systematic random sampling, which involves choosing a random sampling [corrected] start point outside the structure of interest, and sampling relevant objects at [corrected] sites that are placed at pre-determined, equidistant intervals. This has proven to be a very efficient sampling strategy, and is used widely in stereological designs. At the microscopic level, this is most often achieved through the use of a motorized stage that facilitates the systematic random stepping across the structure of interest. Here, we report a simple, precise and cost-effective software-based alternative to accomplishing systematic random sampling under the microscope. We believe that this approach will facilitate the use of stereological designs that employ systematic random sampling in laboratories that lack the resources to acquire costly, fully automated systems.

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

    PubMed

    Sztepanacz, Jacqueline L; Blows, Mark W

    2017-07-01

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

  17. Effect of family disintegration on age at menarche.

    PubMed

    Toromanović, Alma; Tahirović, Husref

    2015-01-01

    The aim of this study was to determine the effect of psychosocial factors on the age at menarche of girls in Federation of Bosnia and Herzegovina (FBH). A cross-sectional study was conducted from September 2002 to May 2003 in all Cantons of the FBH. The random stratified sample included 19.803 girls aged 9.0 to 17.5 years. Data were collected using the status quo method. Probit analysis was used to estimate median age at menarche and 95% confidence intervals. The present study shows that menarche occurred significantly earlier (p<0.05) in girls from dysfunctional families (median: 12.99 years, 95% confidence interval: 12.93-13.05) than in girls who grew up in intact families (median: 13.04 years, 95% confidence interval: 13.01-13.07). Analyzing separately the impact of each of family stressors on age at menarche, we found that menarcheal age was significantly lower in girls from single-mother families, whose parents are divorced, whose one parent is died and where alcoholism in family is present than in girls from intact families. Maturation was found to be earlier in girls from dysfunctional families then in those from intact families after the influence of place of residence and sibship size was eliminated. From our research we can conclude that the girls from dysfunctional families reached earlier age at menarche than their peers who grew up in normal families, and that this effect did not disappear after controlling for socioeconomic variables. Copyright © 2015 by Academy of Sciences and Arts of Bosnia and Herzegovina.

  18. Expecting motherhood? Stratifying reproduction in twenty-first century Scottish abortion practice

    PubMed Central

    Beynon-Jones, Siân M.

    2015-01-01

    This article illustrates how Scottish health professionals involved in contemporary abortion provision construct stratified expectations about women’s reproductive decision-making. Drawing on 42 semi-structured interviews I reveal the contingent discourses through which health professionals constitute the ‘rationality’ of the female subject who requests abortion. Specifically, I illustrate how youth, age, parity and class are mobilised as criteria through which to distinguish ‘types’ of patient whose requests for abortion are deemed particularly understandable or particularly problematic. I conceptualise this process of differentiation as a form of ‘stratified reproduction’ (Colen, 1995; Ginsburg and Rapp, 1995) and argue that it is significant for two reasons. Firstly, it illustrates the operation of dominant discourses concerning abortion and motherhood in twenty-first century Britain. Secondly, it extends the forms of critique which feminist scholarship has, to date, developed of the regulation of abortion provision in the UK. PMID:25774067

  19. Triiodothyronine Supplementation in Infants and Children Undergoing Cardiopulmonary Bypass (TRICC) A Multicenter Placebo-Controlled Randomized Trial: Age Analysis

    PubMed Central

    Portman, Michael A.; Slee, April; Olson, Aaron K.; Cohen, Gordon; Karl, Tom; Tong, Elizabeth; Hastings, Laura; Patel, Hitendra; Reinhartz, Olaf; Mott, Antonio R.; Mainwaring, Richard; Linam, Justin; Danzi, Sara

    2011-01-01

    Background Triiodothyronine levels decrease in infants and children after cardiopulmonary bypass. We tested the primary hypothesis that triiodothyronine (T3) repletion is safe in this population and produces improvements in postoperative clinical outcome. Methods and Results The TRICC study was a prospective, multicenter, double-blind, randomized, placebo-controlled trial in children younger than 2 years old undergoing heart surgery with cardiopulmonary bypass. Enrollment was stratified by surgical diagnosis. Time to extubation (TTE) was the primary outcome. Patients received intravenous T3 as Triostat (n=98) or placebo (n=95), and data were analyzed using Cox proportional hazards. Overall, TTE was similar between groups. There were no differences in adverse event rates, including arrhythmia. Prespecified analyses showed a significant interaction between age and treatment (P=0.0012). For patients younger than 5 months, the hazard ratio (chance of extubation) for Triostat was 1.72. (P=0.0216). Placebo median TTE was 98 hours with 95% confidence interval (CI) of 71 to 142 compared to Triostat TTE at 55 hours with CI of 44 to 92. TTE shortening corresponded to a reduction in inotropic agent use and improvement in cardiac function. For children 5 months of age, or older, Triostat produced a significant delay in median TTE: 16 hours (CI, 7–22) for placebo and 20 hours (CI, 16–45) for Triostat and (hazard ratio, 0.60; P=0.0220). Conclusions T3 supplementation is safe. Analyses using age stratification indicate that T3 supplementation provides clinical advantages in patients younger than 5 months and no benefit for those older than 5 months. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT00027417. PMID:20837917

  20. Describing Typical Capstone Course Experiences from a National Random Sample

    ERIC Educational Resources Information Center

    Grahe, Jon E.; Hauhart, Robert C.

    2013-01-01

    The pedagogical value of capstones has been regularly discussed within psychology. This study presents results from an examination of a national random sample of department webpages and an online survey that characterized the typical capstone course in terms of classroom activities and course administration. The department webpages provide an…

  1. Age-Related Changes in Pharyngeal Lumen Size: A Retrospective MRI Analysis.

    PubMed

    Molfenter, Sonja M; Amin, M R; Branski, R C; Brumm, J D; Hagiwara, M; Roof, S A; Lazarus, C L

    2015-06-01

    Age-related loss of muscle bulk and strength (sarcopenia) is often cited as a potential mechanism underlying age-related changes in swallowing. Our goal was to explore this phenomenon in the pharynx, specifically, by measuring pharyngeal wall thickness and pharyngeal lumen area in a sample of young versus older women. MRI scans of the neck were retrospectively reviewed from 60 women equally stratified into three age groups (20s, 60s, 70+). Four de-identified slices were extracted per scan for randomized, blinded analysis: one mid-sagittal and three axial slices were selected at the anterior inferior border of C2 and C3, and at the pit of the vallecula. Pixel-based measures of pharyngeal wall thickness and pharyngeal lumen area were completed using ImageJ and then converted to metric units. Measures of pharyngeal wall thickness and pharyngeal lumen area were compared between age groups with one-way ANOVAs using Sidak adjustments for post-hoc pairwise comparisons. A significant main effect for age was observed across all variables whereby pharyngeal wall thickness decreased and pharyngeal lumen area increased with advancing age. Pairwise comparisons revealed significant differences between 20s versus 70+ for all variables and 20s versus 60s for all variables except those measured at C2. Effect sizes ranged from 0.54 to 1.34. Consistent with existing sacropenia literature, the pharyngeal muscles appear to atrophy with age and consequently, the size of the pharyngeal lumen increases.

  2. Hierarchical spatial capture-recapture models: Modeling population density from stratified populations

    USGS Publications Warehouse

    Royle, J. Andrew; Converse, Sarah J.

    2014-01-01

    Capture–recapture studies are often conducted on populations that are stratified by space, time or other factors. In this paper, we develop a Bayesian spatial capture–recapture (SCR) modelling framework for stratified populations – when sampling occurs within multiple distinct spatial and temporal strata.We describe a hierarchical model that integrates distinct models for both the spatial encounter history data from capture–recapture sampling, and also for modelling variation in density among strata. We use an implementation of data augmentation to parameterize the model in terms of a latent categorical stratum or group membership variable, which provides a convenient implementation in popular BUGS software packages.We provide an example application to an experimental study involving small-mammal sampling on multiple trapping grids over multiple years, where the main interest is in modelling a treatment effect on population density among the trapping grids.Many capture–recapture studies involve some aspect of spatial or temporal replication that requires some attention to modelling variation among groups or strata. We propose a hierarchical model that allows explicit modelling of group or strata effects. Because the model is formulated for individual encounter histories and is easily implemented in the BUGS language and other free software, it also provides a general framework for modelling individual effects, such as are present in SCR models.

  3. A random sampling approach for robust estimation of tissue-to-plasma ratio from extremely sparse data.

    PubMed

    Chu, Hui-May; Ette, Ene I

    2005-09-02

    his study was performed to develop a new nonparametric approach for the estimation of robust tissue-to-plasma ratio from extremely sparsely sampled paired data (ie, one sample each from plasma and tissue per subject). Tissue-to-plasma ratio was estimated from paired/unpaired experimental data using independent time points approach, area under the curve (AUC) values calculated with the naïve data averaging approach, and AUC values calculated using sampling based approaches (eg, the pseudoprofile-based bootstrap [PpbB] approach and the random sampling approach [our proposed approach]). The random sampling approach involves the use of a 2-phase algorithm. The convergence of the sampling/resampling approaches was investigated, as well as the robustness of the estimates produced by different approaches. To evaluate the latter, new data sets were generated by introducing outlier(s) into the real data set. One to 2 concentration values were inflated by 10% to 40% from their original values to produce the outliers. Tissue-to-plasma ratios computed using the independent time points approach varied between 0 and 50 across time points. The ratio obtained from AUC values acquired using the naive data averaging approach was not associated with any measure of uncertainty or variability. Calculating the ratio without regard to pairing yielded poorer estimates. The random sampling and pseudoprofile-based bootstrap approaches yielded tissue-to-plasma ratios with uncertainty and variability. However, the random sampling approach, because of the 2-phase nature of its algorithm, yielded more robust estimates and required fewer replications. Therefore, a 2-phase random sampling approach is proposed for the robust estimation of tissue-to-plasma ratio from extremely sparsely sampled data.

  4. Breaking through the bandwidth barrier in distributed fiber vibration sensing by sub-Nyquist randomized sampling

    NASA Astrophysics Data System (ADS)

    Zhang, Jingdong; Zhu, Tao; Zheng, Hua; Kuang, Yang; Liu, Min; Huang, Wei

    2017-04-01

    The round trip time of the light pulse limits the maximum detectable frequency response range of vibration in phase-sensitive optical time domain reflectometry (φ-OTDR). We propose a method to break the frequency response range restriction of φ-OTDR system by modulating the light pulse interval randomly which enables a random sampling for every vibration point in a long sensing fiber. This sub-Nyquist randomized sampling method is suits for detecting sparse-wideband- frequency vibration signals. Up to MHz resonance vibration signal with over dozens of frequency components and 1.153MHz single frequency vibration signal are clearly identified for a sensing range of 9.6km with 10kHz maximum sampling rate.

  5. Gravity-induced stresses in stratified rock masses

    USGS Publications Warehouse

    Amadei, B.; Swolfs, H.S.; Savage, W.Z.

    1988-01-01

    This paper presents closed-form solutions for the stress field induced by gravity in anisotropic and stratified rock masses. These rocks are assumed to be laterally restrained. The rock mass consists of finite mechanical units, each unit being modeled as a homogeneous, transversely isotropic or isotropic linearly elastic material. The following results are found. The nature of the gravity induced stress field in a stratified rock mass depends on the elastic properties of each rock unit and how these properties vary with depth. It is thermodynamically admissible for the induced horizontal stress component in a given stratified rock mass to exceed the vertical stress component in certain units and to be smaller in other units; this is not possible for the classical unstratified isotropic solution. Examples are presented to explore the nature of the gravity induced stress field in stratified rock masses. It is found that a decrease in rock mass anisotropy and a stiffening of rock masses with depth can generate stress distributions comparable to empirical hyperbolic distributions previously proposed in the literature. ?? 1988 Springer-Verlag.

  6. Examining an Alternative to Score Equating: A Randomly Equivalent Forms Approach. Research Report. ETS RR-08-14

    ERIC Educational Resources Information Center

    Liao, Chi-Wen; Livingston, Samuel A.

    2008-01-01

    Randomly equivalent forms (REF) of tests in listening and reading for nonnative speakers of English were created by stratified random assignment of items to forms, stratifying on item content and predicted difficulty. The study included 50 replications of the procedure for each test. Each replication generated 2 REFs. The equivalence of those 2…

  7. Graduated driver licensing and motor vehicle crashes involving teenage drivers: an exploratory age-stratified meta-analysis.

    PubMed

    Zhu, Motao; Cummings, Peter; Chu, Haitao; Coben, Jeffrey H; Li, Guohua

    2013-02-01

    Graduated Driver Licensing (GDL) has been implemented in Australia, Canada, New Zealand, USA and Israel. We conducted an exploratory summary of available data to estimate whether GDL effects varied with age. We searched MEDLINE and other sources from 1991-2011. GDL evaluation studies with crashes resulting in injuries or deaths were eligible. They had to provide age-specific incidence rate ratios with CI or information for calculating these quantities. We included studies from individual states or provinces, but excluded national studies. We examined rates based on person-years, not license-years. Of 1397 papers, 144 were screened by abstract and 47 were reviewed. Twelve studies from 11 US states and one Canadian province were selected for meta-analysis for age 16, eight were selected for age 17, and four for age 18. Adjusted rate ratios were pooled using random effects models. The pooled adjusted rate ratios for the association of GDL presence with crash rates was 0.78 (95% CI 0.72 to 0.84) for age 16 years, 0.94 (95% CI 0.93 to 0.96) for 17 and 1.00 (95% CI 0.95 to 1.04) for 18. The difference between these three rate ratios was statistically significant: p<0.001. GDL policies were associated with a 22% reduction in crash rates among 16-year-old drivers, but only a 6% reduction for 17-year-old drivers. GDL showed no association with crashes among 18-year-old drivers. Because we had few studies to summarise, particularly for older adolescents, our findings should be considered exploratory.

  8. The coverage of a random sample from a biological community.

    PubMed

    Engen, S

    1975-03-01

    A taxonomic group will frequently have a large number of species with small abundances. When a sample is drawn at random from this group, one is therefore faced with the problem that a large proportion of the species will not be discovered. A general definition of quantitative measures of "sample coverage" is proposed, and the problem of statistical inference is considered for two special cases, (1) the actual total relative abundance of those species that are represented in the sample, and (2) their relative contribution to the information index of diversity. The analysis is based on a extended version of the negative binomial species frequency model. The results are tabulated.

  9. Prevalence of alcohol-impaired drivers based on random breath tests in a roadside survey in Catalonia (Spain).

    PubMed

    Alcañiz, Manuela; Guillén, Montserrat; Santolino, Miguel; Sánchez-Moscona, Daniel; Llatje, Oscar; Ramon, Lluís

    2014-04-01

    Sobriety checkpoints are not usually randomly located by traffic authorities. As such, information provided by non-random alcohol tests cannot be used to infer the characteristics of the general driving population. In this paper a case study is presented in which the prevalence of alcohol-impaired driving is estimated for the general population of drivers. A stratified probabilistic sample was designed to represent vehicles circulating in non-urban areas of Catalonia (Spain), a region characterized by its complex transportation network and dense traffic around the metropolis of Barcelona. Random breath alcohol concentration tests were performed during spring 2012 on 7596 drivers. The estimated prevalence of alcohol-impaired drivers was 1.29%, which is roughly a third of the rate obtained in non-random tests. Higher rates were found on weekends (1.90% on Saturdays and 4.29% on Sundays) and especially at night. The rate is higher for men (1.45%) than for women (0.64%) and it shows an increasing pattern with age. In vehicles with two occupants, the proportion of alcohol-impaired drivers is estimated at 2.62%, but when the driver was alone the rate drops to 0.84%, which might reflect the socialization of drinking habits. The results are compared with outcomes in previous surveys, showing a decreasing trend in the prevalence of alcohol-impaired drivers over time. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Improving depression and enhancing resilience in family dementia caregivers: a pilot randomized placebo-controlled trial of escitalopram

    PubMed Central

    Lavretsky, H.; Siddarth, P.; Irwin, M. R.

    2009-01-01

    Background This study examined the potential of an antidepressant drug, escitalopram, to improve depression, resilience to stress, and quality of life in family dementia caregivers in a randomized placebo-controlled double-blind trial. Methods Forty family caregivers (43–91 years of age, 25 children and 15 spouses; 26 women) who were taking care of their relatives with Alzheimer’s disease were randomized to receive either escitalopram 10 mg/day or placebo for 12 weeks. Severity of depression, resilience, burden, distress, quality of life, and severity of care-recipient’s cognitive and behavioral disturbances were assessed at baseline and over the course of the study. The Hamilton Depression Rating Scale (HDRS) scores at baseline ranged between 10–28. The groups were stratified by the diagnosis of major and minor depression. Results Most outcomes favored escitalopram over placebo. The severity of depression improved and the remission rate was greater with the drug compared to placebo. Measures of anxiety, resilience, burden and distress improved on escitalopram compared to placebo. Discussion Among caregivers, this small randomized controlled trial found that escitalopram use resulted in improvement in depression, resilience, burden and distress, and quality of life. Our results need to be confirmed in a larger sample. PMID:20104071

  11. Factors Affecting Retirement Attitude among Elementary School Teachers

    ERIC Educational Resources Information Center

    Hsu, Wan-Chen; Chiang, Chia-Hsun; Chuang, Hsueh-Hua

    2015-01-01

    This study investigated the relationships of teacher efficacy, perceived organizational control, and the teacher-student age gap with teachers' retirement attitudes. Stratified random sampling was adopted to collect survey responses. A total of 498 valid surveys from 33 elementary schools were collected. Correlational analyses revealed significant…

  12. Geohydrology and water quality of stratified-drift aquifers in the middle Merrimack River basin, south-central New Hampshire

    USGS Publications Warehouse

    Ayotte, Joseph D.; Toppin, Kenneth W.

    1995-01-01

    analyzed for aquifer yield by use of a two-dimensional, finite-difference ground-water-flow model. Yield of the Goffstown aquifer was estimated to be 2.5 million gallons per day. Sensitivity analysis showed that the estimate of aquifer yield was most sensitive to changes in hydraulic conductivity. The amount of water induced into the aquifer from the Piscataquog River was most affected by changes in estimates of streambed conductance. Results of analysis of water samples from 10 test wells indicate that, with some exceptions, water in the stratified-drift aquifers generally meets U.S. Environmental Protection Agency primary and secondary drinking-water regulations. Water from two wells had elevated sodium concentrations, waterfront two wells had elevated concentrations of dissolved iron, and waterfront seven wells had elevated concentrations of manganese. Known areas of contamination were avoided during water-quality sampling.

  13. Accuracy and sampling error of two age estimation techniques using rib histomorphometry on a modern sample.

    PubMed

    García-Donas, Julieta G; Dyke, Jeffrey; Paine, Robert R; Nathena, Despoina; Kranioti, Elena F

    2016-02-01

    Most age estimation methods are proven problematic when applied in highly fragmented skeletal remains. Rib histomorphometry is advantageous in such cases; yet it is vital to test and revise existing techniques particularly when used in legal settings (Crowder and Rosella, 2007). This study tested Stout & Paine (1992) and Stout et al. (1994) histological age estimation methods on a Modern Greek sample using different sampling sites. Six left 4th ribs of known age and sex were selected from a modern skeletal collection. Each rib was cut into three equal segments. Two thin sections were acquired from each segment. A total of 36 thin sections were prepared and analysed. Four variables (cortical area, intact and fragmented osteon density and osteon population density) were calculated for each section and age was estimated according to Stout & Paine (1992) and Stout et al. (1994). The results showed that both methods produced a systemic underestimation of the individuals (to a maximum of 43 years) although a general improvement in accuracy levels was observed when applying the Stout et al. (1994) formula. There is an increase of error rates with increasing age with the oldest individual showing extreme differences between real age and estimated age. Comparison of the different sampling sites showed small differences between the estimated ages suggesting that any fragment of the rib could be used without introducing significant error. Yet, a larger sample should be used to confirm these results. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  14. A 30-month worksite-based lifestyle program to promote cardiovascular health in middle-aged bank employees: Design of the TANSNIP-PESA randomized controlled trial.

    PubMed

    Coffeng, Jennifer K; van der Ploeg, Hidde P; Castellano, José M; Fernández-Alvira, Juan M; Ibáñez, Borja; García-Lunar, Inés; van der Beek, Allard J; Fernández-Ortiz, Antonio; Mocoroa, Agustín; García-Leal, Laura; Cárdenas, Evelyn; Rojas, Carolina; Martínez-Castro, María I; Santiago-Sacristán, Silvia; Fernández-Gallardo, Miriam; Mendiguren, José M; Bansilal, Sameer; van Mechelen, Willem; Fuster, Valentín

    2017-02-01

    Cardiovascular disease (CVD) is the leading cause of death worldwide. With atherosclerosis as the underlying cause for many CVD events, prevention or reduction of subclinical atherosclerotic plaque burden (SAPB) through a healthier lifestyle may have substantial public health benefits. The objective was to describe the protocol of a randomized controlled trial investigating the effectiveness of a 30-month worksite-based lifestyle program aimed to promote cardiovascular health in participants having a high or a low degree of SAPB compared with standard care. We will conduct a randomized controlled trial including middle-aged bank employees from the Progression of Early Subclinical Atherosclerosis cohort, stratified by SAPB (high SAPB n=260, low SAPB n=590). Within each stratum, participants will be randomized 1:1 to receive a lifestyle program or standard care. The program consists of 3 elements: (a) 12 personalized lifestyle counseling sessions using Motivational Interviewing over a 30-month period, (b) a wrist-worn physical activity tracker, and (c) a sit-stand workstation. Primary outcome measure is a composite score of blood pressure, physical activity, sedentary time, body weight, diet, and smoking (ie, adapted Fuster-BEWAT score) measured at baseline and at 1-, 2-, and 3-year follow-up. The study will provide insights into the effectiveness of a 30-month worksite-based lifestyle program to promote cardiovascular health compared with standard care in participants with a high or low degree of SAPB. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Aging in the three-dimensional random-field Ising model

    NASA Astrophysics Data System (ADS)

    von Ohr, Sebastian; Manssen, Markus; Hartmann, Alexander K.

    2017-07-01

    We studied the nonequilibrium aging behavior of the random-field Ising model in three dimensions for various values of the disorder strength. This allowed us to investigate how the aging behavior changes across the ferromagnetic-paramagnetic phase transition. We investigated a large system size of N =2563 spins and up to 108 Monte Carlo sweeps. To reach these necessary long simulation times, we employed an implementation running on Intel Xeon Phi coprocessors, reaching single-spin-flip times as short as 6 ps. We measured typical correlation functions in space and time to extract a growing length scale and corresponding exponents.

  16. Stratified randomization controls better for batch effects in 450K methylation analysis: a cautionary tale.

    PubMed

    Buhule, Olive D; Minster, Ryan L; Hawley, Nicola L; Medvedovic, Mario; Sun, Guangyun; Viali, Satupaitea; Deka, Ranjan; McGarvey, Stephen T; Weeks, Daniel E

    2014-01-01

    Batch effects in DNA methylation microarray experiments can lead to spurious results if not properly handled during the plating of samples. Two pilot studies examining the association of DNA methylation patterns across the genome with obesity in Samoan men were investigated for chip- and row-specific batch effects. For each study, the DNA of 46 obese men and 46 lean men were assayed using Illumina's Infinium HumanMethylation450 BeadChip. In the first study (Sample One), samples from obese and lean subjects were examined on separate chips. In the second study (Sample Two), the samples were balanced on the chips by lean/obese status, age group, and census region. We used methylumi, watermelon, and limma R packages, as well as ComBat, to analyze the data. Principal component analysis and linear regression were, respectively, employed to identify the top principal components and to test for their association with the batches and lean/obese status. To identify differentially methylated positions (DMPs) between obese and lean males at each locus, we used a moderated t-test. Chip effects were effectively removed from Sample Two but not Sample One. In addition, dramatic differences were observed between the two sets of DMP results. After "removing" batch effects with ComBat, Sample One had 94,191 probes differentially methylated at a q-value threshold of 0.05 while Sample Two had zero differentially methylated probes. The disparate results from Sample One and Sample Two likely arise due to the confounding of lean/obese status with chip and row batch effects. Even the best possible statistical adjustments for batch effects may not completely remove them. Proper study design is vital for guarding against spurious findings due to such effects.

  17. Stratified randomization controls better for batch effects in 450K methylation analysis: a cautionary tale

    PubMed Central

    Buhule, Olive D.; Minster, Ryan L.; Hawley, Nicola L.; Medvedovic, Mario; Sun, Guangyun; Viali, Satupaitea; Deka, Ranjan; McGarvey, Stephen T.; Weeks, Daniel E.

    2014-01-01

    Background: Batch effects in DNA methylation microarray experiments can lead to spurious results if not properly handled during the plating of samples. Methods: Two pilot studies examining the association of DNA methylation patterns across the genome with obesity in Samoan men were investigated for chip- and row-specific batch effects. For each study, the DNA of 46 obese men and 46 lean men were assayed using Illumina's Infinium HumanMethylation450 BeadChip. In the first study (Sample One), samples from obese and lean subjects were examined on separate chips. In the second study (Sample Two), the samples were balanced on the chips by lean/obese status, age group, and census region. We used methylumi, watermelon, and limma R packages, as well as ComBat, to analyze the data. Principal component analysis and linear regression were, respectively, employed to identify the top principal components and to test for their association with the batches and lean/obese status. To identify differentially methylated positions (DMPs) between obese and lean males at each locus, we used a moderated t-test. Results: Chip effects were effectively removed from Sample Two but not Sample One. In addition, dramatic differences were observed between the two sets of DMP results. After “removing” batch effects with ComBat, Sample One had 94,191 probes differentially methylated at a q-value threshold of 0.05 while Sample Two had zero differentially methylated probes. The disparate results from Sample One and Sample Two likely arise due to the confounding of lean/obese status with chip and row batch effects. Conclusion: Even the best possible statistical adjustments for batch effects may not completely remove them. Proper study design is vital for guarding against spurious findings due to such effects. PMID:25352862

  18. Aging in Community Nutrition, Diet Therapy, and Nutrition and Aging Textbooks

    ERIC Educational Resources Information Center

    O'Neill, Peggy Schafer; Wellman, Nancy S.; Himburg, Susan P.; Johnson, Paulette; Elfenbein, Pamela

    2005-01-01

    Using content analysis, this study evaluated the aging content and context in 11 nutrition sub-specialty textbooks: community nutrition (n = 3), diet therapy (n = 4), and nutrition and aging (n = 4). Pages with paragraphs on aging were identified in community nutrition and diet therapy textbooks, and 10% random samples of pages were evaluated in…

  19. Mortality following the Haitian earthquake of 2010: a stratified cluster survey

    PubMed Central

    2013-01-01

    Introduction Research that seeks to better understand vulnerability to earthquakes and risk factors associated with mortality in low resource settings is critical to earthquake preparedness and response efforts. This study aims to characterize mortality and associated risk factors in the 2010 Haitian earthquake. Methods In January 2011, a survey of the earthquake affected Haitian population was conducted in metropolitan Port-au-Prince. A stratified 60x20 cluster design (n = 1200 households) was used with 30 clusters sampled in both camp and neighborhood locations. Households were surveyed regarding earthquake impact, current living conditions, and unmet needs. Results Mortality was estimated at 24 deaths (confidence interval [CI]: 20–28) per 1,000 in the sample population. Using two approaches, extrapolation of the survey mortality rate to the exposed population yielded mortality estimates ranging from a low of 49,033 to a high of 86,555. No significant difference in mortality was observed by sex (p = .786); however, age was significant with adults age 50+ years facing increased mortality risk. Odds of death were not significantly higher in camps, with 27 deaths per 1,000 (CI: 22–34), compared to neighborhoods, where the death rate was 19 per 1,000 (CI: 15–25; p = 0.080). Crowding and residence in a multistory building were also associated with increased risk of death. Conclusions Haiti earthquake mortality estimates are widely varied, though epidemiologic surveys conducted to date suggest lower levels of mortality than officially reported figures. Strategies to mitigate future mortality burden in future earthquakes should consider improvements to the built environment that are feasible in urban resource-poor settings. PMID:23618373

  20. The Bootstrap, the Jackknife, and the Randomization Test: A Sampling Taxonomy.

    PubMed

    Rodgers, J L

    1999-10-01

    A simple sampling taxonomy is defined that shows the differences between and relationships among the bootstrap, the jackknife, and the randomization test. Each method has as its goal the creation of an empirical sampling distribution that can be used to test statistical hypotheses, estimate standard errors, and/or create confidence intervals. Distinctions between the methods can be made based on the sampling approach (with replacement versus without replacement) and the sample size (replacing the whole original sample versus replacing a subset of the original sample). The taxonomy is useful for teaching the goals and purposes of resampling schemes. An extension of the taxonomy implies other possible resampling approaches that have not previously been considered. Univariate and multivariate examples are presented.

  1. Does topical amethocaine gel reduce pain from heel prick blood sampling in premature infants? A randomized double-blind cross-over controlled study

    PubMed Central

    Patel, Amita; Czerniawski, Barbara; Gray, Shari; Lui, Eric

    2003-01-01

    BACKGROUND: Heel prick blood sampling is the most common painful invasive procedure performed on neonates. Currently, there are no effective ways to provide pain relief from this painful procedure. OBJECTIVE: To assess the efficacy of the topical anesthetic amethocaine 4% gel (Ametop, Smith & Nephew Inc, St Laurent) in reducing the pain of heel prick blood sampling in neonates. METHODS: A randomized, double-blind, placebo controlled, crossover trial was conducted. Neonates between 33 to 37 weeks’ gestational age in their first seven days of life were eligible. Heel prick blood sampling was performed on each participant twice. Each infant was randomly assigned to receive either amethocaine 4% gel or placebo to the heel for the first prick, and then received the alternative agent for the second prick. Prick pain was assessed using both Premature Infant Pain Profile (PIPP) and Neonatal Infant Pain Scale (NIPS). Squeeze pain was assessed by NIPS. RESULTS: Ten babies were recruited. There were no significant differences in the average PIPP and NIPS scores between the treatment and placebo groups for both prick and squeeze pains from heel prick blood sampling. For prick pain, linear-regression showed significant correlation between the PIPP and NIPS scores. No adverse reactions were observed after application of either the active or placebo agents. CONCLUSION: Topical amethocaine 4% gel is not shown to reduce prick and squeeze pains significantly from heel prick blood sampling in neonates between 33 to 37 weeks’ gestational age. Further studies are needed to find ways to provide effective pain relief from this common procedure. PMID:20020001

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

    PubMed

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

    2018-01-01

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

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

    PubMed Central

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

    2018-01-01

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

  4. Physical fitness percentile charts for children aged 6-10 from Portugal.

    PubMed

    Roriz De Oliveira, M S; Seabra, A; Freitas, D; Eisenmann, J C; Maia, J

    2014-12-01

    The present study aims (1) to provide reference percentile charts for the following measures of Physical Fitness (PF): the sit-and-reach, handgrip, standing long jump, 50 yards' dash, 4x10m shuttle run and 1-mile run/walk tests in children aged 6 to 10 years, and (2) to compare the performance of the Portuguese children with their age- and sex peers. A total of 3804 Portuguese children (1985 boys and 1819 girls) aged 6-10 years old participated in this study. The sample was stratified from 20 public elementary schools and children were randomly selected in each school. Charts were separately built for each sex using the LMS method. Boys showed better results than girls in handgrip, standing long jump, 50 yards' dash, 4x10 m shuttle run and 1-mile run/walk, while girls are better performers than boys in sit-and-reach. Age- and gender- percentiles for a set of physical fitness tests for 6-10 year old (primary school) Portuguese children have been established. Boys showed greater overall PF than girls, except in the flexibility test, in which girls performed better. The reported normative values provide ample opportunities to accurately detect individual changes during childhood. These reference values are especially important in healthcare and educational settings, and can be added to the worldwide literature on physical fitness values in children.

  5. Prevalence and Risk Factors of Overweight and Obesity among Children Aged 6–59 Months in Cameroon: A Multistage, Stratified Cluster Sampling Nationwide Survey

    PubMed Central

    Tchoubi, Sébastien; Sobngwi-Tambekou, Joëlle; Noubiap, Jean Jacques N.; Asangbeh, Serra Lem; Nkoum, Benjamin Alexandre; Sobngwi, Eugene

    2015-01-01

    Background Childhood obesity is one of the most serious public health challenges of the 21st century. The prevalence of overweight and obesity among children (<5 years) in Cameroon, based on weight-for-height index, has doubled between 1991 and 2006. This study aimed to determine the prevalence and risk factors of overweight and obesity among children aged 6 months to 5 years in Cameroon in 2011. Methods Four thousand five hundred and eighteen children (2205 boys and 2313 girls) aged between 6 to 59 months were sampled in the 2011 Demographic Health Survey (DHS) database. Body Mass Index (BMI) z-scores based on WHO 2006 reference population was chosen to estimate overweight (BMI z-score > 2) and obesity (BMI for age > 3). Regression analyses were performed to investigate risk factors of overweight/obesity. Results The prevalence of overweight and obesity was 8% (1.7% for obesity alone). Boys were more affected by overweight than girls with a prevalence of 9.7% and 6.4% respectively. The highest prevalence of overweight was observed in the Grassfield area (including people living in West and North-West regions) (15.3%). Factors that were independently associated with overweight and obesity included: having overweight mother (adjusted odds ratio (aOR) = 1.51; 95% CI 1.15 to 1.97) and obese mother (aOR = 2.19; 95% CI = 155 to 3.07), compared to having normal weight mother; high birth weight (aOR = 1.69; 95% CI 1.24 to 2.28) compared to normal birth weight; male gender (aOR = 1.56; 95% CI 1.24 to 1.95); low birth rank (aOR = 1.35; 95% CI 1.06 to 1.72); being aged between 13–24 months (aOR = 1.81; 95% CI = 1.21 to 2.66) and 25–36 months (aOR = 2.79; 95% CI 1.93 to 4.13) compared to being aged 45 to 49 months; living in the grassfield area (aOR = 2.65; 95% CI = 1.87 to 3.79) compared to living in Forest area. Muslim appeared as a protective factor (aOR = 0.67; 95% CI 0.46 to 0.95).compared to Christian religion. Conclusion This study underlines a high prevalence of

  6. The first report of Japanese antimicrobial use measured by national database based on health insurance claims data (2011-2013): comparison with sales data, and trend analysis stratified by antimicrobial category and age group.

    PubMed

    Yamasaki, Daisuke; Tanabe, Masaki; Muraki, Yuichi; Kato, Genta; Ohmagari, Norio; Yagi, Tetsuya

    2018-04-01

    Our objective was to evaluate the utility of the national database (NDB) based on health insurance claims data for antimicrobial use (AMU) surveillance in medical institutions in Japan. The population-weighted total AMU expressed as defined daily doses (DDDs) per 1000 inhabitants per day (DID) was measured by the NDB. The data were compared with our previous study measured by the sales data. Trend analysis of DID from 2011 to 2013 and subgroup analysis stratified by antimicrobial category and age group were performed. There was a significant linear correlation between the AMUs measured by the sales data and the NDB. Total oral and parenteral AMUs (expressed in DID) were 1.04-fold from 12.654 in 2011 to 13.202 in 2013 and 1.13-fold from 0.734 to 0.829, respectively. Percentage of oral form among total AMU was high with more than 94% during the study period. AMU in the children group (0-14 years) decreased from 2011 to 2013 regardless of dosage form, although the working age group (15-64 years) and elderly group (65 and above years) increased. Oral AMU in the working age group was approximately two-thirds of those in the other age groups. In contrast, parenteral AMU in the elderly group was extremely high compared to the other age groups. The trend of AMU stratified by antimicrobial category and age group were successfully measured using the NDB, which can be a tool to monitor outcome indices for the national action plan on antimicrobial resistance.

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

    NASA Technical Reports Server (NTRS)

    Han, Kuoruey

    1990-01-01

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

  8. Dental erosion among children aged 3-6 years and its associated indicators.

    PubMed

    Tao, Dan-Ying; Hao, Gu; Lu, Hai-Xia; Tian, Yu; Feng, Xi-Ping

    2015-01-01

    To analyze the status quo of dental erosion in 3- to 6-year-old children in Shanghai. A stratified, cluster, multistage random sampling methods was applied to 3- to 6-year-old children in Shanghai in 2012. Both questionnaire and clinical oral examination were performed in the survey. The questionnaire included general information, such as age, gender, parental education, dietary habit, oral health behavior, general medical health, and socioeconomic status. The clinical examination focused on the eroded tooth surface and dental erosion extent. SPSS v19.0 software package was utilized for statistical analysis. A total of 1,837 children aged 3-6 years were randomly selected in Shanghai. The overall dental erosion prevalence was 15.1 percent. Among different age groups, a relatively high prevalence of 17.1 percent was found in the 4-year-old group, and a relatively low prevalence of 12.0 percent was observed in the 3-year-old group. Surprisingly, there was no significant difference among the four age groups. The occurrence of dental erosion was influenced by habits of vinegar/coffee/tea consumption, mother's educational background, birthplace, and regurgitation (P < 0.05). The dental erosion prevalence in 3- to 6-year-old children in Shanghai appears to be close to that of other Chinese provinces as well as that observed in most of surveys carried out in different parts of the world. Efforts should be made to raise public awareness about the disease. Moreover, further studies targeted to explore the relationship between dental erosion and risk factors are needed. It is also necessary to establish a unified diagnostic standard for future epidemiological investigations. © 2015 American Association of Public Health Dentistry.

  9. Graduated driver licensing and motor vehicle crashes involving teenage drivers: an exploratory age-stratified meta-analysis

    PubMed Central

    Zhu, Motao; Cummings, Peter; Chu, Haitao; Coben, Jeffrey H; Li, Guohua

    2014-01-01

    Objective Graduated Driver Licensing (GDL) has been implemented in Australia, Canada, New Zealand, USA and Israel. We conducted an exploratory summary of available data to estimate whether GDL effects varied with age. Methods We searched MEDLINE and other sources from 1991–2011. GDL evaluation studies with crashes resulting in injuries or deaths were eligible. They had to provide age-specific incidence rate ratios with CI or information for calculating these quantities. We included studies from individual states or provinces, but excluded national studies. We examined rates based on person-years, not license-years. Results Of 1397 papers, 144 were screened by abstract and 47 were reviewed. Twelve studies from 11 US states and one Canadian province were selected for meta-analysis for age 16, eight were selected for age 17, and four for age 18. Adjusted rate ratios were pooled using random effects models. The pooled adjusted rate ratios for the association of GDL presence with crash rates was 0.78 (95% CI 0.72 to 0.84) for age 16 years, 0.94 (95% CI 0.93 to 0.96) for 17 and 1.00 (95% CI 0.95 to 1.04) for 18. The difference between these three rate ratios was statistically significant: p<0.001. Conclusions GDL policies were associated with a 22% reduction in crash rates among 16-year-old drivers, but only a 6% reduction for 17-year-old drivers. GDL showed no association with crashes among 18-year-old drivers. Because we had few studies to summarise, particularly for older adolescents, our findings should be considered exploratory. PMID:23211352

  10. Complement pathway biomarkers and age-related macular degeneration

    PubMed Central

    Gemenetzi, M; Lotery, A J

    2016-01-01

    In the age-related macular degeneration (AMD) ‘inflammation model', local inflammation plus complement activation contributes to the pathogenesis and progression of the disease. Multiple genetic associations have now been established correlating the risk of development or progression of AMD. Stratifying patients by their AMD genetic profile may facilitate future AMD therapeutic trials resulting in meaningful clinical trial end points with smaller sample sizes and study duration. PMID:26493033

  11. Corrections of stratified tropospheric delays in SAR interferometry: Validation with global atmospheric models

    NASA Astrophysics Data System (ADS)

    Doin, Marie-Pierre; Lasserre, Cécile; Peltzer, Gilles; Cavalié, Olivier; Doubre, Cécile

    2010-05-01

    The main limiting factor on the accuracy of Interferometric SAR measurements (InSAR) comes from phase propagation delays through the troposphere. The delay can be divided into a stratified component, which correlates with the topography and often dominates the tropospheric signal, and a turbulent component. We use Global Atmospheric Models (GAM) to estimate the stratified phase delay and delay-elevation ratio at epochs of SAR acquisitions, and compare them to observed phase delay derived from SAR interferograms. Three test areas are selected with different geographic and climatic environments and with large SAR archive available. The Lake Mead, Nevada, USA is covered by 79 ERS1/2 and ENVISAT acquisitions, the Haiyuan Fault area, Gansu, China, by 24 ERS1/2 acquisitions, and the Afar region, Republic of Djibouti, by 91 Radarsat acquisitions. The hydrostatic and wet stratified delays are computed from GAM as a function of atmospheric pressure P, temperature T, and water vapor partial pressure e vertical profiles. The hydrostatic delay, which depends on ratio P/T, varies significantly at low elevation and cannot be neglected. The wet component of the delay depends mostly on the near surface specific humidity. GAM predicted delay-elevation ratios are in good agreement with the ratios derived from InSAR data away from deforming zones. Both estimations of the delay-elevation ratio can thus be used to perform a first order correction of the observed interferometric phase to retrieve a ground motion signal of low amplitude. We also demonstrate that aliasing of daily and seasonal variations in the stratified delay due to uneven sampling of SAR data significantly bias InSAR data stacks or time series produced after temporal smoothing. In all three test cases, the InSAR data stacks or smoothed time series present a residual stratified delay of the order of the expected deformation signal. In all cases, correcting interferograms from the stratified delay removes all these

  12. Corrections of stratified tropospheric delays in SAR interferometry: Validation with global atmospheric models

    NASA Astrophysics Data System (ADS)

    Doin, M.-P.; Lasserre, C.; Peltzer, G.; Cavalié, O.; Doubre, C.

    2009-09-01

    The main limiting factor on the accuracy of Interferometric SAR measurements (InSAR) comes from phase propagation delays through the troposphere. The delay can be divided into a stratified component, which correlates with the topography and often dominates the tropospheric signal, and a turbulent component. We use Global Atmospheric Models (GAM) to estimate the stratified phase delay and delay-elevation ratio at epochs of SAR acquisitions, and compare them to observed phase delay derived from SAR interferograms. Three test areas are selected with different geographic and climatic environments and with large SAR archive available. The Lake Mead, Nevada, USA is covered by 79 ERS1/2 and ENVISAT acquisitions, the Haiyuan Fault area, Gansu, China, by 24 ERS1/2 acquisitions, and the Afar region, Republic of Djibouti, by 91 Radarsat acquisitions. The hydrostatic and wet stratified delays are computed from GAM as a function of atmospheric pressure P, temperature T, and water vapor partial pressure e vertical profiles. The hydrostatic delay, which depends on ratio P/ T, varies significantly at low elevation and cannot be neglected. The wet component of the delay depends mostly on the near surface specific humidity. GAM predicted delay-elevation ratios are in good agreement with the ratios derived from InSAR data away from deforming zones. Both estimations of the delay-elevation ratio can thus be used to perform a first order correction of the observed interferometric phase to retrieve a ground motion signal of low amplitude. We also demonstrate that aliasing of daily and seasonal variations in the stratified delay due to uneven sampling of SAR data significantly bias InSAR data stacks or time series produced after temporal smoothing. In all three test cases, the InSAR data stacks or smoothed time series present a residual stratified delay of the order of the expected deformation signal. In all cases, correcting interferograms from the stratified delay removes all these

  13. Differences in Mathematics Teachers' Perceived Preparedness to Demonstrate Competence in Secondary School Mathematics Content by Teacher Characteristics

    ERIC Educational Resources Information Center

    Ng'eno, J. K.; Chesimet, M. C.

    2016-01-01

    A sample of 300 mathematics teachers drawn from a population of 1500 participated in this study. The participants were selected using systematic random sampling and stratified random sampling (stratified by qualification and gender). The data was collected using self-report questionnaires for mathematics teachers. One tool was used to collect…

  14. Psychological Distress and Related Factors in Female College Students

    ERIC Educational Resources Information Center

    Vazquez, Fernando L.; Otero, Patricia; Diaz, Olga

    2012-01-01

    Objective: This study assessed the psychological distress in Spanish college women and analyzed it in relation to sociodemographic and academic factors. Participants and Methods: The authors selected a stratified random sampling of 1,043 college women (average age of 22.2 years). Sociodemographic and academic information were collected, and…

  15. Perceptions of Professionalism among Individuals in the Child Care Field

    ERIC Educational Resources Information Center

    Martin, Sue; Meyer, James; Jones, Robin Caudle; Nelson, Laverne; Ting, Ling

    2010-01-01

    Individuals working with young children, birth through age five, continue to strive for professional recognition. Factors that contribute to a person's feelings about being a child care professional were investigated. Stratified random sampling was used for data collection. Participants in the study responded to mailed questionnaires concerning a…

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  17. Specialist mental health consultation for depression in Australian aged care residents with dementia: a cluster randomized trial.

    PubMed

    McSweeney, Kate; Jeffreys, Aimee; Griffith, Joanne; Plakiotis, Chris; Kharsas, Renee; O'Connor, Daniel W

    2012-11-01

    This cluster randomized controlled trial sought to determine whether multidisciplinary specialist mental health consultation was more effective than care as usual in treating the depression of aged care residents with dementia. Three hundred and eighty nine aged care residents were screened for dementia and major depression. Forty four were ultimately included in the intervention sample, selected from 20 aged care facilities located in Melbourne, Australia. Facilities were randomly allocated to an intervention condition involving the provision of multidisciplinary specialist consultation regarding the best-practice management of depression in dementia, or to a care as usual condition. Consultations involved individually tailored medical and psychosocial recommendations provided to care staff and general practitioners. All residents participated in a comprehensive pre-intervention diagnostic assessment, including the administration of the Cornell Scale for Depression in Dementia. This assessment was repeated approximately 15 weeks post-intervention by a rater blind to study condition. Multidisciplinary specialist mental health consultation was significantly more effective than care as usual in treating the clinical depression of aged care residents with dementia (p < 0.05, partial η(2)  = 0.16). At follow-up, the mean Cornell Scale for Depression in Dementia score for the intervention group was 9.47, compared with 14.23 for the control group. In addition, 77% of the intervention group no longer met criteria for major depression. The results of this study suggest that the psychosocial and medical management of depressed aged care residents can be improved by increasing access to specialist mental health consultation. Copyright © 2012 John Wiley & Sons, Ltd.

  18. Spatial inventory integrating raster databases and point sample data. [Geographic Information System for timber inventory

    NASA Technical Reports Server (NTRS)

    Strahler, A. H.; Woodcock, C. E.; Logan, T. L.

    1983-01-01

    A timber inventory of the Eldorado National Forest, located in east-central California, provides an example of the use of a Geographic Information System (GIS) to stratify large areas of land for sampling and the collection of statistical data. The raster-based GIS format of the VICAR/IBIS software system allows simple and rapid tabulation of areas, and facilitates the selection of random locations for ground sampling. Algorithms that simplify the complex spatial pattern of raster-based information, and convert raster format data to strings of coordinate vectors, provide a link to conventional vector-based geographic information systems.

  19. Randomized Trial Using Gonadotropin-Releasing Hormone Agonist Triptorelin for the Preservation of Ovarian Function During (Neo)Adjuvant Chemotherapy for Breast Cancer

    PubMed Central

    Munster, Pamela N.; Moore, Amy P.; Ismail-Khan, Roohi; Cox, Charles E.; Lacevic, Mensura; Gross-King, Margaret; Xu, Ping; Carter, W. Bradford; Minton, Susan E.

    2012-01-01

    Purpose Chemotherapy-induced amenorrhea is a serious concern for women undergoing cancer therapy. This prospective randomized trial evaluated the use of gonadotropin-releasing hormone (GnRH) analog triptorelin to preserve ovarian function in women treated with chemotherapy for early-stage breast cancer. Patients and Methods Premenopausal women age 44 years or younger were randomly assigned to receive either triptorelin or no triptorelin during (neo)adjuvant chemotherapy and were further stratified by age (< 35, 35 to 39, > 39 years), estrogen receptor status, and chemotherapy regimen. Objectives included the resumption of menses and serial monitoring of follicle-stimulating hormone (FSH) and inhibin A and B levels. Results Targeted for 124 patients with a planned 5-year follow-up, the trial was stopped for futility after 49 patients were enrolled (median age, 39 years; range, 21 to 43 years); 47 patients were treated according to assigned groups with four cycles of adriamycin plus cyclophosphamide alone or followed by four cycles of paclitaxel or six cycles of fluorouracil, epirubicin, and cyclophosphamide. Menstruation resumed in 19 (90%) of 21 patients in the control group and in 23 (88%) of 26 in the triptorelin group (P= .36). Menses returned after a median of 5.8 months (range, 1 to 19 months) after completion of chemotherapy in the triptorelin versus 5.0 months (range, 0 to 28 months) in the control arm (P= .58). Two patients (age 26 and 35 years at random assignment) in the control group had spontaneous pregnancies with term deliveries. FSH and inhibin B levels correlated with menstrual status. Conclusion When stratified for age, estrogen receptor status, and treatment regimen, amenorrhea rates on triptorelin were comparable to those seen in the control group. PMID:22231041

  20. A comparison of lead lengths for mini-fyke nets to sample age-0 gar species

    USGS Publications Warehouse

    Long, James M.; Snow, Richard A.; Patterson, Chas P.

    2016-01-01

    Mini-fyke nets are often used to sample small-bodied fishes in shallow (<1 m depth) water, especially in vegetated shoreline habitats where seines are ineffective. Recent interest in gar (Lepisosteidae) ecology and conservation led us to explore the use of mini-fyke nets to capture age-0 gar and specifically how capture is affected by lead length of the fyke net. In the summers of 2012, 2013, and 2015, mini-fyke nets with two different lead lengths (4.57 m and 9.14 m) were set at random sites in backwaters and coves of the Red River arm of Lake Texoma, Oklahoma. Mean CPUE (catch-per-unit-effort; number per net night) was significantly lower for mini-fyke nets with short leads (0.52) compared to those with long leads (1.51). Additionally, Spotted Gar (Lepisosteus oculatus) were captured at a higher rate than the other three gar species present in Lake Texoma, although this could have been an artifact of sampling location. We found that differences in length-frequency of captured gar between gear types were nearly significant, with total length ranging from 47mm to 590mm. Mini-fyke nets with longer leads increased the efficiency of sampling for age-0 gar by increasing catch rate without affecting estimates of other population parameters and appear to be useful for this purpose. 

  1. Age-stratified outcomes after robotic-assisted laparoscopic radical prostatectomy.

    PubMed

    Zorn, Kevin C; Mendiola, Frederick P; Rapp, David E; Mikhail, Albert A; Lin, Shang; Orvieto, Marcelo A; Zagaja, Gregory P; Shalhav, Arieh L

    2007-01-01

    We sought to evaluate post-operative return of urinary and sexual function in men undergoing robotic-assisted laparoscopic radical prostatectomy (RLRP). Prospective assessment of urinary continence and sexual function was performed in patients undergoing RLRP. Subjective assessment involved the use of the validated RAND-36 Item Health Survey/UCLA Prostate Cancer Index questionnaire. Questionnaires were completed pre-operatively and at 1, 3, 6 and 12 months post-operatively. Subset analyses were performed to assess the effect of age on functional outcomes. A total of 338 consecutive patients underwent RLRP between February 2003 and August 2005. Included patients for evaluation comprised of 21, 129, and 150 patients, aged <50, 50-59, and ≥60 years old, respectively. Kaplan-Meier curve analysis demonstrated that younger men (<60 years) achieved subjective continence significantly earlier than older age group (≥60 years) (P = 0.02). Continence rates, however, equalized among all age groups at 1 year follow-up. Younger men (<50 years) also demonstrated a quicker and greater return of sexual function (P = 0.01), which persisted through assessment at 1 year post-operatively. Our results suggest that younger men may have an earlier return of continence and potency when compared to men > 60 years. Despite this finding, continence outcomes appear to be equal among age groups after 1 year of follow-up. Moreover, men < 60 years continue to report superior potency outcomes compared to men > 60 years at 1 year post-operatively. Such findings are valuable in counseling patients undergoing RLRP.

  2. Determination of reference values for elevated fasting and random insulin levels and their associations with metabolic risk factors among rural Pakistanis from Sindh Province.

    PubMed

    Ahmadani, Muhammad Yakoob; Hakeem, Rubina; Fawwad, Asher; Basit, Abdul; Shera, A Samad

    2008-06-01

    To assess insulin levels and their association with metabolic risk factors (family history of diabetes, abnormal glucose tolerance, hypertension, overweight and android obesity) among a representative group of Pakistan. The study data was taken from the database of a population-based survey conducted in Sindh Province, Pakistan, in 1994 to assess the prevalence of diabetes mellitus and impaired glucose tolerance (IGT). Through stratified random sampling; oral glucose tolerance tests were performed in 967 adults; every fifth sample was estimated for fasting and random (2-hour post-75 gm glucose load) insulin levels. The total number of metabolic risk factors was counted for each subject, and their association with insulin levels studied. Of the 130 subjects, 56.1% were females and 95.4% were Sindhi. The mean age of males and females was 43.84 and 40.61 years, respectively. Family history for diabetes and frequency of overweight had significant positive associations with both fasting and random insulin levels (P < 0.05). Association between hypertension and insulin levels was significant only for random insulin levels, and between android obesity, abnormal glucose tolerance, or male gender and insulin levels only for fasting insulin levels (P < 0.05). Metabolic risk factors had significant positive associations with both fasting (r = 0.351 P = 0.000) as well as random insulin levels (r = 0.364 P = 0.000). This paper provides baseline pioneering information applicable to the Pakistani population. Furthermore, the observations made in this study about differences in association of fasting or random insulin levels with various metabolic risk factors highlight the possibility of using either of them for risk assessment. This finding needs to be assessed in a larger and nationally representative sample.

  3. Radiative transfer in a plane stratified dielectric

    NASA Technical Reports Server (NTRS)

    Wilheit, T. T., Jr.

    1975-01-01

    A model is developed for calculating radiative transfer in a stratified dielectric. This model is used to show that the reflectivity of a stratified dielectric is primarily determined by gradients in the real part of the refractive index over distances on the order of 1/10 wavelength in the medium. The effective temperature of the medium is determined by the thermodynamic temperature profile over distances of the order delta T.

  4. Effect of initial spacing on mechanical properties of lumber sawn from unthinned slash pine at age 40

    Treesearch

    Robert H. McAlister; Alexander Clark; Joseph R. Saucier

    1997-01-01

    The effect of initial planting density on strength and stiffness of slash pine (Pinus elliotti Engelm. var elliotti) from a 40-year-old plantation on the Georgia Coastal Plain was examined. A stratified random sample of trees with diameters at breast height ranging from 8 to 16 inches from replicated stands representing tree spacing of 6 by 8, 8 by 8, 10 by 10, and 15...

  5. Using a fast Fourier method to model sound propagation in a stratified atmosphere over a stratified porous-elastic ground

    NASA Technical Reports Server (NTRS)

    Tooms, S.; Attenborough, K.

    1990-01-01

    Using a Fast Fourier integration method and a global matrix method for solution of the boundary condition equations at all interfaces simultaneously, a useful tool for predicting acoustic propagation in a stratified fluid over a stratified porous-elastic solid was developed. The model for the solid is a modified Biot-Stoll model incorporating four parameters describing the pore structure corresponding to the Rayleigh-Attenborough rigid-porous structure model. The method is also compared to another Fast Fourier code (CERL-FFP) which models the ground as an impedance surface under a horizontally stratified air. Agreement with the CERL FFP is good. The effects on sound propagation of a combination of ground elasticity, complex ground structure, and atmospheric conditions are demonstrated by theoretical results over a snow layer, and experimental results over a model ground surface.

  6. Stratified cost-utility analysis of C-Leg versus mechanical knees: Findings from an Italian sample of transfemoral amputees.

    PubMed

    Cutti, Andrea Giovanni; Lettieri, Emanuele; Del Maestro, Martina; Radaelli, Giovanni; Luchetti, Martina; Verni, Gennero; Masella, Cristina

    2017-06-01

    The fitting rate of the C-Leg electronic knee (Otto-Bock, D) has increased steadily over the last 15 years. Current cost-utility studies, however, have not considered the patients' characteristics. To complete a cost-utility analysis involving C-Leg and mechanical knee users; "age at the time of enrollment," "age at the time of first prosthesis," and "experience with the current type of prosthesis" are assumed as non-nested stratification parameters. Cohort retrospective. In all, 70 C-Leg and 57 mechanical knee users were selected. For each stratification criteria, we evaluated the cost-utility of C-Leg versus mechanical knees by computing the incremental cost-utility ratio, that is, the ratio of the "difference in cost" and the "difference in utility" of the two technologies. Cost consisted of acquisition, maintenance, transportation, and lodging expenses. Utility was measured in terms of quality-adjusted life years, computed on the basis of participants' answers to the EQ-5D questionnaire. Patients over 40 years at the time of first prosthesis were the only group featuring an incremental cost-utility ratio (88,779 €/quality-adjusted life year) above the National Institute for Health and Care Excellence practical cost-utility threshold (54,120 €/quality-adjusted live year): C-Leg users experience a significant improvement of "mobility," but limited outcomes on "usual activities," "self-care," "depression/anxiety," and reduction of "pain/discomfort." The stratified cost-utility results have relevant clinical implications and provide useful information for practitioners in tailoring interventions. Clinical relevance A cost-utility analysis that considered patients characteristics provided insights on the "affordability" of C-Leg compared to mechanical knees. In particular, results suggest that C-Leg has a significant impact on "mobility" for first-time prosthetic users over 40 years, but implementation of specific low-cost physical

  7. The King Pre-Retirement Checklist: Assessing Differences in Pre-Retirement Planning.

    ERIC Educational Resources Information Center

    Zitzow, Darryl; King, Donald N.

    In an effort to assess the retirement preparedness of Midwestern populations above the age of 28, the King Pre-Retirement Checklist was administered to a sampling of 458 persons randomly selected and proportionally stratified by geographic location and community size. Factors examined were financial, social, family cohesion, mobility/health,…

  8. Early Adolescent Outcomes of Institutionally Deprived and Non-Deprived Adoptees. III. Quasi-Autism

    ERIC Educational Resources Information Center

    Rutter, Michael; Kreppner, Jana; Croft, Carla; Murin, Marianna; Colvert, Emma; Beckett, Celia; Castle, Jenny; Sonuga-Barke, Edmund

    2007-01-01

    Background: Some young children reared in profoundly depriving institutions have been found to show autistic-like patterns, but the developmental significance of these features is unknown. Methods: A randomly selected, age-stratified, sample of 144 children who had experienced an institutional upbringing in Romania and who were adopted by UK…

  9. Phylogenetic analysis accounting for age-dependent death and sampling with applications to epidemics.

    PubMed

    Lambert, Amaury; Alexander, Helen K; Stadler, Tanja

    2014-07-07

    The reconstruction of phylogenetic trees based on viral genetic sequence data sequentially sampled from an epidemic provides estimates of the past transmission dynamics, by fitting epidemiological models to these trees. To our knowledge, none of the epidemiological models currently used in phylogenetics can account for recovery rates and sampling rates dependent on the time elapsed since transmission, i.e. age of infection. Here we introduce an epidemiological model where infectives leave the epidemic, by either recovery or sampling, after some random time which may follow an arbitrary distribution. We derive an expression for the likelihood of the phylogenetic tree of sampled infectives under our general epidemiological model. The analytic concept developed in this paper will facilitate inference of past epidemiological dynamics and provide an analytical framework for performing very efficient simulations of phylogenetic trees under our model. The main idea of our analytic study is that the non-Markovian epidemiological model giving rise to phylogenetic trees growing vertically as time goes by can be represented by a Markovian "coalescent point process" growing horizontally by the sequential addition of pairs of coalescence and sampling times. As examples, we discuss two special cases of our general model, described in terms of influenza and HIV epidemics. Though phrased in epidemiological terms, our framework can also be used for instance to fit macroevolutionary models to phylogenies of extant and extinct species, accounting for general species lifetime distributions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Age and sex prevalence of infectious dermatoses among primary school children in a rural South-Eastern Nigerian community

    PubMed Central

    Kalu, Eziyi Iche; Wagbatsoma, Victoria; Ogbaini-Emovon, Ephraim; Nwadike, Victor Ugochukwu; Ojide, Chiedozie Kingsley

    2015-01-01

    Introduction Various dermatoses, due to their morbidity characteristics, have been shown to negatively impact on learning. The most epidemiologically important seem to be the infectious types because of their transmissibility and amenability to simple school-health measures. The aim of this study was to assess the prevalence and sex/age correlates of infectious dermatoses in a rural South-eastern Nigerian community. Methods The pupils were proportionately recruited from the three primary schools based on school population. Stratified simple random sampling method was adopted and a table of random numbers was used to select required pupils from each arm. Clinical and laboratory examination was done to establish diagnoses of infectious skin disease. Data collected were analyzed using SPSS version 16. Results The 400 pupils consisted of 153 males and 247 females. Age range was between 6 and 12 years. The prevalence of infectious dermatoses was 72.3%. The five most prevalent clinical forms of infectious dermatoses, in order of decreasing prevalence, were tinea capitis (35.2%), scabies (10.5%), tinea corporis (5.8%), tinea pedis (5.5%), and impetigo (5.0%). More cases, generally, occurred among males than females (80.4% vs 67.2%)); while some specific clinical types, pediculosis and seborrheic dermatitis, exhibited predilection for females. Pyodermas and scabies were significantly more prevalent in the 7-9 age-group; while tinea capitis, tinea corporis, seborrheic dermatitis and pediculosis were more associated with ≥10 age-group. Conclusion Infectious dermatoses were highly prevalent in the surveyed population. Many of the clinical types exhibited sex- and age-specificity. PMID:26430479

  11. The Expected Sample Variance of Uncorrelated Random Variables with a Common Mean and Some Applications in Unbalanced Random Effects Models

    ERIC Educational Resources Information Center

    Vardeman, Stephen B.; Wendelberger, Joanne R.

    2005-01-01

    There is a little-known but very simple generalization of the standard result that for uncorrelated random variables with common mean [mu] and variance [sigma][superscript 2], the expected value of the sample variance is [sigma][superscript 2]. The generalization justifies the use of the usual standard error of the sample mean in possibly…

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

    PubMed

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

    2016-01-01

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

  13. A novel 3D Cartesian random sampling strategy for Compressive Sensing Magnetic Resonance Imaging.

    PubMed

    Valvano, Giuseppe; Martini, Nicola; Santarelli, Maria Filomena; Chiappino, Dante; Landini, Luigi

    2015-01-01

    In this work we propose a novel acquisition strategy for accelerated 3D Compressive Sensing Magnetic Resonance Imaging (CS-MRI). This strategy is based on a 3D cartesian sampling with random switching of the frequency encoding direction with other K-space directions. Two 3D sampling strategies are presented. In the first strategy, the frequency encoding direction is randomly switched with one of the two phase encoding directions. In the second strategy, the frequency encoding direction is randomly chosen between all the directions of the K-Space. These strategies can lower the coherence of the acquisition, in order to produce reduced aliasing artifacts and to achieve a better image quality after Compressive Sensing (CS) reconstruction. Furthermore, the proposed strategies can reduce the typical smoothing of CS due to the limited sampling of high frequency locations. We demonstrated by means of simulations that the proposed acquisition strategies outperformed the standard Compressive Sensing acquisition. This results in a better quality of the reconstructed images and in a greater achievable acceleration.

  14. Cross-Sectional Analysis of Time-Dependent Data: Mean-Induced Association in Age-Heterogeneous Samples and an Alternative Method Based on Sequential Narrow Age-Cohort Samples

    ERIC Educational Resources Information Center

    Hofer, Scott M.; Flaherty, Brian P.; Hoffman, Lesa

    2006-01-01

    The effect of time-related mean differences on estimates of association in cross-sectional studies has not been widely recognized in developmental and aging research. Cross-sectional studies of samples varying in age have found moderate to high levels of shared age-related variance among diverse age-related measures. These findings may be…

  15. Occupational therapy practitioners' perceptions of important competencies for handwriting evaluation and intervention in school-aged children.

    PubMed

    Giroux, Peter; Woodall, William; Weber, Mark; Bailey, Jessica

    2012-02-01

    The primary purpose of this study was to identify the practitioner competencies that occupational therapists perceive as important for handwriting evaluation and intervention in school-aged children. A secondary purpose was to compare the practitioner perceptions of those in school-based practice with those from other primary practice settings. A stratified random sample of 376 occupational therapists recruited from a national professional organization database participated by completing a survey instrument containing 80 competency items. A majority of the 80 practitioner competency items were perceived to be of high importance to the respondent groups. A significance difference in perception when comparing the school-based practitioners to all other practitioners was revealed in only 3-12 competency summary categories. Practitioner competency survey items were perceived to be of high importance to the participants. School-based practitioner perceptions of competency were, for the most part, mainly similar to those in other primary practice settings.

  16. Operationalizing multimorbidity and autonomy for health services research in aging populations - the OMAHA study

    PubMed Central

    2011-01-01

    Background As part of a Berlin-based research consortium on health in old age, the OMAHA (Operationalizing Multimorbidity and Autonomy for Health Services Research in Aging Populations) study aims to develop a conceptual framework and a set of standardized instruments and indicators for continuous monitoring of multimorbidity and associated health care needs in the population 65 years and older. Methods/Design OMAHA is a longitudinal epidemiological study including a comprehensive assessment at baseline and at 12-month follow-up as well as brief intermediate telephone interviews at 6 and 18 months. In order to evaluate different sampling procedures and modes of data collection, the study is conducted in two different population-based samples of men and women aged 65 years and older. A geographically defined sample was recruited from an age and sex stratified random sample from the register of residents in Berlin-Mitte (Berlin OMAHA study cohort, n = 299) for assessment by face-to-face interview and examination. A larger nationwide sample (German OMAHA study cohort, n = 730) was recruited for assessment by telephone interview among participants in previous German Telephone Health Surveys. In both cohorts, we successfully applied a multi-dimensional set of instruments to assess multimorbidity, functional disability in daily life, autonomy, quality of life (QoL), health care services utilization, personal and social resources as well as socio-demographic and biographical context variables. Response rates considerably varied between the Berlin and German OMAHA study cohorts (22.8% vs. 59.7%), whereas completeness of follow-up at month 12 was comparably high in both cohorts (82.9% vs. 81.2%). Discussion The OMAHA study offers a wide spectrum of data concerning health, functioning, social involvement, psychological well-being, and cognitive capacity in community-dwelling older people in Germany. Results from the study will add to methodological and content

  17. Vortex ring motions in stratified media

    NASA Astrophysics Data System (ADS)

    Auvity, Bruno; Koulal, Mokrane; Dupont, Pascal; Peerhossaini, Hassan

    2003-11-01

    The behavior of vortex rings generated in a stably stratified media has received only weak treatment in the literature. This configuration is believed to shed light on the basic phenomena involved in the collapse of wake in stratified fluid. The present study focused on experimental observations of the formation, the advection and the collapse of horizontal vortex rings in stratified media. Stable continuous vertical stratification was produced in a tank using the well-known two-tanks method. The generation of vortex ring was realized moving a piston through a tube. The maximum piston stroke achievable was seven tube diameters. The problem is mainly characterized by two parameters : the initial Reynolds number and the initial Froude number of the vortex ring. Both these numbers were varied in the study. The Reynolds number based on the tube diameter and piston velocity was in the range 1,500 - 5,500 and the Froude number based on the same parameters in the range 1.4 - 4.7. Dye visualizations were performed from the top and the side of the tank showing the vortex ring may develop an important asymmetry. Different processes to the complete collapse of the vortex ring were identified.

  18. Age- and Sex-Specific Causal Effects of Adiposity on Cardiovascular Risk Factors

    PubMed Central

    Fall, Tove; Hägg, Sara; Ploner, Alexander; Mägi, Reedik; Fischer, Krista; Draisma, Harmen H.M.; Sarin, Antti-Pekka; Benyamin, Beben; Ladenvall, Claes; Åkerlund, Mikael; Kals, Mart; Esko, Tõnu; Nelson, Christopher P.; Kaakinen, Marika; Huikari, Ville; Mangino, Massimo; Meirhaeghe, Aline; Kristiansson, Kati; Nuotio, Marja-Liisa; Kobl, Michael; Grallert, Harald; Dehghan, Abbas; Kuningas, Maris; de Vries, Paul S.; de Bruijn, Renée F.A.G.; Willems, Sara M.; Heikkilä, Kauko; Silventoinen, Karri; Pietiläinen, Kirsi H.; Legry, Vanessa; Giedraitis, Vilmantas; Goumidi, Louisa; Syvänen, Ann-Christine; Strauch, Konstantin; Koenig, Wolfgang; Lichtner, Peter; Herder, Christian; Palotie, Aarno; Menni, Cristina; Uitterlinden, André G.; Kuulasmaa, Kari; Havulinna, Aki S.; Moreno, Luis A.; Gonzalez-Gross, Marcela; Evans, Alun; Tregouet, David-Alexandre; Yarnell, John W.G.; Virtamo, Jarmo; Ferrières, Jean; Veronesi, Giovanni; Perola, Markus; Arveiler, Dominique; Brambilla, Paolo; Lind, Lars; Kaprio, Jaakko; Hofman, Albert; Stricker, Bruno H.; van Duijn, Cornelia M.; Ikram, M. Arfan; Franco, Oscar H.; Cottel, Dominique; Dallongeville, Jean; Hall, Alistair S.; Jula, Antti; Tobin, Martin D.; Penninx, Brenda W.; Peters, Annette; Gieger, Christian; Samani, Nilesh J.; Montgomery, Grant W.; Whitfield, John B.; Martin, Nicholas G.; Groop, Leif; Spector, Tim D.; Magnusson, Patrik K.; Amouyel, Philippe; Boomsma, Dorret I.; Nilsson, Peter M.; Järvelin, Marjo-Riitta; Lyssenko, Valeriya; Metspalu, Andres; Strachan, David P.; Salomaa, Veikko; Ripatti, Samuli; Pedersen, Nancy L.; Prokopenko, Inga; McCarthy, Mark I.

    2015-01-01

    Observational studies have reported different effects of adiposity on cardiovascular risk factors across age and sex. Since cardiovascular risk factors are enriched in obese individuals, it has not been easy to dissect the effects of adiposity from those of other risk factors. We used a Mendelian randomization approach, applying a set of 32 genetic markers to estimate the causal effect of adiposity on blood pressure, glycemic indices, circulating lipid levels, and markers of inflammation and liver disease in up to 67,553 individuals. All analyses were stratified by age (cutoff 55 years of age) and sex. The genetic score was associated with BMI in both nonstratified analysis (P = 2.8 × 10−107) and stratified analyses (all P < 3.3 × 10−30). We found evidence of a causal effect of adiposity on blood pressure, fasting levels of insulin, C-reactive protein, interleukin-6, HDL cholesterol, and triglycerides in a nonstratified analysis and in the <55-year stratum. Further, we found evidence of a smaller causal effect on total cholesterol (P for difference = 0.015) in the ≥55-year stratum than in the <55-year stratum, a finding that could be explained by biology, survival bias, or differential medication. In conclusion, this study extends previous knowledge of the effects of adiposity by providing sex- and age-specific causal estimates on cardiovascular risk factors. PMID:25712996

  19. Age-related changes in the craniofacial region in a modern Greek population sample of known age and sex.

    PubMed

    Chovalopoulou, Maria-Eleni; Bertsatos, Andreas; Papageorgopoulou, Christina

    2017-07-01

    The aim of this paper is to investigate ageing changes in craniofacial region in both sexes and evaluate whether these shape changes are substantial to achieve age discrimination of samples used in anthropological analyses. The study sample consisted of 157 crania of known sex and age (81 males and 76 females) belonging to individuals who lived in Greece during the twentieth century. The sample was divided in three age groups: young adults (YA, 18-39 years old), middle adults (MA, 40-59 years old) and old adults (OA, >60 years old). The three-dimensional coordinates of 31 ecto-cranial landmarks were digitized using a Microscribe 3DX contact digitizer, and landmark configurations were analyzed using the generalized least-squares Procrustes method. The results indicate that both males and females show significant difference among the age groups; however, shape differences can not be used for age group discrimination due to a large range on the accuracy of age group classification. The morphometric changes related to age were different between sexes.

  20. Influences of sampling size and pattern on the uncertainty of correlation estimation between soil water content and its influencing factors

    NASA Astrophysics Data System (ADS)

    Lai, Xiaoming; Zhu, Qing; Zhou, Zhiwen; Liao, Kaihua

    2017-12-01

    In this study, seven random combination sampling strategies were applied to investigate the uncertainties in estimating the hillslope mean soil water content (SWC) and correlation coefficients between the SWC and soil/terrain properties on a tea + bamboo hillslope. One of the sampling strategies is the global random sampling and the other six are the stratified random sampling on the top, middle, toe, top + mid, top + toe and mid + toe slope positions. When each sampling strategy was applied, sample sizes were gradually reduced and each sampling size contained 3000 replicates. Under each sampling size of each sampling strategy, the relative errors (REs) and coefficients of variation (CVs) of the estimated hillslope mean SWC and correlation coefficients between the SWC and soil/terrain properties were calculated to quantify the accuracy and uncertainty. The results showed that the uncertainty of the estimations decreased as the sampling size increasing. However, larger sample sizes were required to reduce the uncertainty in correlation coefficient estimation than in hillslope mean SWC estimation. Under global random sampling, 12 randomly sampled sites on this hillslope were adequate to estimate the hillslope mean SWC with RE and CV ≤10%. However, at least 72 randomly sampled sites were needed to ensure the estimated correlation coefficients with REs and CVs ≤10%. Comparing with all sampling strategies, reducing sampling sites on the middle slope had the least influence on the estimation of hillslope mean SWC and correlation coefficients. Under this strategy, 60 sites (10 on the middle slope and 50 on the top and toe slopes) were enough to ensure the estimated correlation coefficients with REs and CVs ≤10%. This suggested that when designing the SWC sampling, the proportion of sites on the middle slope can be reduced to 16.7% of the total number of sites. Findings of this study will be useful for the optimal SWC sampling design.

  1. Correcting Classifiers for Sample Selection Bias in Two-Phase Case-Control Studies

    PubMed Central

    Theis, Fabian J.

    2017-01-01

    Epidemiological studies often utilize stratified data in which rare outcomes or exposures are artificially enriched. This design can increase precision in association tests but distorts predictions when applying classifiers on nonstratified data. Several methods correct for this so-called sample selection bias, but their performance remains unclear especially for machine learning classifiers. With an emphasis on two-phase case-control studies, we aim to assess which corrections to perform in which setting and to obtain methods suitable for machine learning techniques, especially the random forest. We propose two new resampling-based methods to resemble the original data and covariance structure: stochastic inverse-probability oversampling and parametric inverse-probability bagging. We compare all techniques for the random forest and other classifiers, both theoretically and on simulated and real data. Empirical results show that the random forest profits from only the parametric inverse-probability bagging proposed by us. For other classifiers, correction is mostly advantageous, and methods perform uniformly. We discuss consequences of inappropriate distribution assumptions and reason for different behaviors between the random forest and other classifiers. In conclusion, we provide guidance for choosing correction methods when training classifiers on biased samples. For random forests, our method outperforms state-of-the-art procedures if distribution assumptions are roughly fulfilled. We provide our implementation in the R package sambia. PMID:29312464

  2. 40 CFR 761.306 - Sampling 1 meter square surfaces by random selection of halves.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Sampling 1 meter square surfaces by...(b)(3) § 761.306 Sampling 1 meter square surfaces by random selection of halves. (a) Divide each 1 meter square portion where it is necessary to collect a surface wipe test sample into two equal (or as...

  3. 40 CFR 761.306 - Sampling 1 meter square surfaces by random selection of halves.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Sampling 1 meter square surfaces by...(b)(3) § 761.306 Sampling 1 meter square surfaces by random selection of halves. (a) Divide each 1 meter square portion where it is necessary to collect a surface wipe test sample into two equal (or as...

  4. 40 CFR 761.306 - Sampling 1 meter square surfaces by random selection of halves.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Sampling 1 meter square surfaces by...(b)(3) § 761.306 Sampling 1 meter square surfaces by random selection of halves. (a) Divide each 1 meter square portion where it is necessary to collect a surface wipe test sample into two equal (or as...

  5. 40 CFR 761.306 - Sampling 1 meter square surfaces by random selection of halves.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Sampling 1 meter square surfaces by...(b)(3) § 761.306 Sampling 1 meter square surfaces by random selection of halves. (a) Divide each 1 meter square portion where it is necessary to collect a surface wipe test sample into two equal (or as...

  6. 40 CFR 761.306 - Sampling 1 meter square surfaces by random selection of halves.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Sampling 1 meter square surfaces by...(b)(3) § 761.306 Sampling 1 meter square surfaces by random selection of halves. (a) Divide each 1 meter square portion where it is necessary to collect a surface wipe test sample into two equal (or as...

  7. Influence of cigarette smoking on coronary artery and aortic calcium among random samples from populations of middle-age Japanese and Korean men

    PubMed Central

    Hirooka, Nobutaka; Kadowaki, Takashi; Sekikawa, Akira; Ueshima, Hirotsugu; Choo, Jina; Miura, Katsuyuki; Okamura, Tomonori; Fujiyoshi, Akira; Kadowaki, Sayaka; Kadota, Aya; Nakamura, Yasuyuki; Maegawa, Hiroshi; Kashiwagi, Atsunori; Masaki, Kamal; Sutton-Tyrrell, Kim; Kuller, Lewis H.; Curb, J. David; Shin, Chol

    2012-01-01

    Background Cigarette smoking is a risk factor of coronary heart disease (CHD). Vascular calcification such as coronary artery calcium (CAC) and aortic calcium (AC) is associated with CHD. We hypothesized that cigarette smoking is associated with coronary artery and aortic calcifications in Japanese and Koreans with high smoking prevalence. Methods Random samples from populations of 313 Japanese and 302 Korean men aged 40 to 49 were examined for calcification of the coronary artery and aorta using electron beam computed tomography. Coronary artery calcium (CAC) and aortic calcium (AC) were quantified using the Agatston score. We examined the associations of cigarette smoking with CAC and AC after adjusting for conventional risk factors and alcohol consumption. Current and past smokers were combined and categorized into two groups using median pack-years as a cutoff point in each of Japanese and Koreans. The never smoker group was used as a reference for the multiple logistic regression analyses. Results The odds ratios of CAC (score ≥10) for smokers with higher pack-years were 2.9 in Japanese (P<0.05) and 1.3 in Koreans (non-significant) compared to never smokers. The odds ratios of AC (score ≥100) for smokers with higher pack-years were 10.4 in Japanese (P<0.05) and 3.6 in Koreans (P<0.05). Conclusion Cigarette smoking with higher pack-years is significantly associated with CAC and AC in Japanese men, while cigarette smoking with higher pack-years is significantly associated with AC but not significantly with CAC in Korean men. PMID:22844083

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

    ERIC Educational Resources Information Center

    Taylor, Laura; Doehler, Kirsten

    2015-01-01

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

  9. Effectiveness of lipid-lowering therapy among a sample of patients in Colombia.

    PubMed

    Machado-Alba, Jorge Enrique; Murillo-Muñoz, Maria Monica; Machado-Duque, Manuel Enrique

    2013-06-01

    To determine the effectiveness of lipid-lowering therapy in a sample of patients affiliated with the Sistema General de Seguridad Social en Salud (the Colombian health system). A cross-sectional study was conducted from 1 January 2010-30 June 2011. From a total of 8 316 patients in 10 cities, a random sample of 600 was stratified according to dyslipidemia. Information on sociodemographic and anthropometric characteristics, risk factors, and pharmacological and laboratory variables were obtained from medical records. Subjects were predominantly female (56.2%), with a mean age of 65.1 ± 11.5 years; 93.2% had hypertension; 29.0%, diabetes mellitus; and 10.2%, a history of myocardial infarction. The patients were being treated with lovastatin (84.1%) or gemfibrozil (12.3%)-both at doses below what is recommended-or atorvastatin (1.8%). In patients with high cardiovascular risk, 38.6% achieved goals for low-density lipoprotein cholesterol (LDL-C) levels (<100 mg/dL). Among those at moderate risk, 49.4% reached the target level (< 130 mg/dL). On average, there was a 4.9% reduction in LDL-C. Sex, age, history of cardiovascular disease and/or diabetes mellitus, use of hydrochlorothiazide, and poor therapy adherence were statistically associated with a lack of dyslipidemia control. Because a lack LDL-C control occurred in patients with two or more of the following variables: male, more than 55 years of age, diabetes and/or a history of cardiovascular disease, received lower doses of lovastatin, or non-adherent to treatment, it is recommended that medication be increased based on clearly-defined therapeutic goals and that comorbidities be assessed and effectively treated.

  10. The 40-Something randomized controlled trial to prevent weight gain in mid-age women.

    PubMed

    Williams, Lauren T; Hollis, Jenna L; Collins, Clare E; Morgan, Philip J

    2013-10-25

    Obesity prevention is a major public health priority. Despite the health risks associated with weight gain, there has been a distinct lack of research into effective interventions to prevent, rather than treat, obesity particularly at high risk life stages such as menopause in women. This paper describes the rationale for and design of a 2-year randomized controlled trial (RCT) (the 40-Something Study) aimed at testing the feasibility and efficacy of a relatively low intensity intervention designed to achieve weight control in non-obese women about to enter the menopause transition. The study is a parallel-group RCT consisting of 12 months of intervention (Phase 1) and 12 months of monitoring (Phase 2). Non-obese pre-menopausal healthy females 44-50 years of age were screened, stratified according to Body Mass Index (BMI) category (18.5-24.9 and 25-29.9 kg/m²) and randomly assigned to one of two groups: motivational interviewing (MI) intervention (n = 28), or a self-directed intervention (SDI) (control) (n = 26). The MI intervention consisted of five consultations with health professionals (four with a Dietitian and one with an Exercise Physiologist) who applied components of MI counselling to consultations with the women over a 12 month period. The SDI was developed as a control and these participants received print materials only. Outcome measures were collected at baseline, three, 12, 18 and 24 months and included weight (primary outcome), waist circumference, body composition, blood pressure, plasma markers of metabolic syndrome risk, dietary intake, physical activity and quality of life. Analysis of covariance will be used to investigate outcomes according to intervention type and duration (comparing baseline, 12 and 24 months). The 40-Something study is the first RCT aimed at preventing menopausal weight gain in Australian women. Importantly, this paper describes the methods used to evaluate whether a relatively low intensity, health professional led

  11. Prevalence of uncorrected refractive errors among children aged 3-10 years in western Saudi Arabia

    PubMed Central

    Alrahili, Nojood Hameed R.; Jadidy, Esraa S.; Alahmadi, Bayan Sulieman H.; Abdula’al, Mohammed F.; Jadidy, Alaa S.; Alhusaini, Abdulaziz A.; Mojaddidi, Moaz A.; Al-Barry, Maan A.

    2017-01-01

    Objectives: To determine the prevalence of uncorrected refractive errors (URE) among children 3-10 years and to affirm the necessity of a national school-based visual screening program for school-aged children. Methods: This retrospective cross-sectional study was conducted in Medina, Saudi Arabia in 2015. Children were selected through a multistage stratified random sampling from 8 kindergarten and 8 primary schools. Those included were screened to diagnose UREs using a visual acuity chart and an auto refractometer according to American guidelines. The prevalence and types of UREs were estimated. Results: Of the 2121 children enumerated, 1893 were examined, yielding a response rate of 89.3%. The prevalence of UREs was 34.9% (95% CI = 32.8%-37.1%), with significant differences in different age groups. The prevalence of astigmatism (25.3%) was higher compared to that of anisometropia (7.4%), hypermetropia (1.5%), and myopia (0.7%). Risk of uncorrected refractive error was positively associated with age, and this was noted in astigmatism, myopia, and anisometropia. In addition, the risk of hypermetropia was associated with boys and that of myopia was associated with girls. Conclusions: The prevalence of UREs, particularly astigmatism, was high among children aged 3-10 years in Medina, with significant age differences. Vision screening programs targeting kindergarten and primary schoolchildren are crucial to lessen the risk of preventable visual impairment due to UREs. PMID:28762432

  12. Prevalence of uncorrected refractive errors among children aged 3-10 years in western Saudi Arabia.

    PubMed

    Alrahili, Nojood Hameed R; Jadidy, Esraa S; Alahmadi, Bayan Sulieman H; Abdula'al, Mohammed F; Jadidy, Alaa S; Alhusaini, Abdulaziz A; Mojaddidi, Moaz A; Al-Barry, Maan A

    2017-08-01

    To determine the prevalence of uncorrected refractive errors (URE) among children 3-10 years and to affirm the necessity of a national school-based visual screening program for school-aged children. Methods: This retrospective cross-sectional study was conducted in Medina, Saudi Arabia in 2015. Children were selected through a multistage stratified random sampling from 8 kindergarten and 8 primary schools. Those included were screened to diagnose UREs using a visual acuity chart and an auto refractometer according to American guidelines. The prevalence and types of UREs were estimated. Results: Of the 2121 children enumerated, 1893 were examined, yielding a response rate of 89.3%. The prevalence of UREs was 34.9% (95% CI = 32.8%-37.1%), with significant differences in different age groups. The prevalence of astigmatism (25.3%) was higher compared to that of anisometropia (7.4%), hypermetropia (1.5%), and myopia (0.7%). Risk of uncorrected refractive error was positively associated with age, and this was noted in astigmatism, myopia, and anisometropia. In addition, the risk of hypermetropia was associated with boys and that of myopia was associated with girls. Conclusions: The prevalence of UREs, particularly astigmatism, was high among children aged 3-10 years in Medina, with significant age differences. Vision screening programs targeting kindergarten and primary schoolchildren are crucial to lessen the risk of preventable visual impairment due to UREs.

  13. Geospatial techniques for developing a sampling frame of watersheds across a region

    USGS Publications Warehouse

    Gresswell, Robert E.; Bateman, Douglas S.; Lienkaemper, George; Guy, T.J.

    2004-01-01

    Current land-management decisions that affect the persistence of native salmonids are often influenced by studies of individual sites that are selected based on judgment and convenience. Although this approach is useful for some purposes, extrapolating results to areas that were not sampled is statistically inappropriate because the sampling design is usually biased. Therefore, in recent investigations of coastal cutthroat trout (Oncorhynchus clarki clarki) located above natural barriers to anadromous salmonids, we used a methodology for extending the statistical scope of inference. The purpose of this paper is to apply geospatial tools to identify a population of watersheds and develop a probability-based sampling design for coastal cutthroat trout in western Oregon, USA. The population of mid-size watersheds (500-5800 ha) west of the Cascade Range divide was derived from watershed delineations based on digital elevation models. Because a database with locations of isolated populations of coastal cutthroat trout did not exist, a sampling frame of isolated watersheds containing cutthroat trout had to be developed. After the sampling frame of watersheds was established, isolated watersheds with coastal cutthroat trout were stratified by ecoregion and erosion potential based on dominant bedrock lithology (i.e., sedimentary and igneous). A stratified random sample of 60 watersheds was selected with proportional allocation in each stratum. By comparing watershed drainage areas of streams in the general population to those in the sampling frame and the resulting sample (n = 60), we were able to evaluate the how representative the subset of watersheds was in relation to the population of watersheds. Geospatial tools provided a relatively inexpensive means to generate the information necessary to develop a statistically robust, probability-based sampling design.

  14. Stratifying repellent-treated pine seed.

    Treesearch

    T.A. Harrington

    1960-01-01

    Germinative capacity of loblolly, shortleaf, and Virginia pine may be seriously reduced if the seed is repellent-coated and then stratified when fresh. In contrast, cold storage for a few months may largely forestall damage from later repellent treatment and stratification.

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

    PubMed

    Deng, Hong-Wen

    2003-11-01

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

  16. ASSESSMENT OF THE WRITTEN LANGUAGE OF DEAF STUDENTS.

    ERIC Educational Resources Information Center

    MARKS, CLAUDE H.; STUCKLESS, E. ROSS

    THIS INVESTIGATION WAS CONDUCTED TO DESCRIBE THE WRITTEN LANGUAGE OF DEAF STUDENTS BETWEEN 10 AND 18 YEARS OF AGE IN TERMS OF SIX MEASURABLE VARIABLES, AND TO RELATE THESE VARIABLES TO TEACHER JUDGMENTS OF QUALITY OF LANGUAGE. TEN STRATIFIED RANDOM SAMPLES OF COMPOSITIONS BY DEAF STUDENTS WERE SELECTED FROM 14 RESIDENTIAL AND DAY EDUCATIONAL…

  17. Practising Mental Rotation Using Interactive Desktop Mental Rotation Trainer (iDeMRT)

    ERIC Educational Resources Information Center

    Rafi, Ahmad; Samsudin, Khairulanuar

    2009-01-01

    An experimental study involving 30 undergraduates (mean age = 20.5 years) in mental rotation (MR) training was conducted in an interactive Desktop Mental Rotation Trainer (iDeMRT). Stratified random sampling assigned students into one experimental group and one control group. The former trained in iDeMRT and the latter trained in conventional…

  18. Understanding exchanges across turbulent/stratified zones interfaces

    NASA Astrophysics Data System (ADS)

    Le Bars, M.; Ribeiro, A.; Le Gal, P.; Aurnou, J. M.

    2013-12-01

    In many geophysical and astrophysical situations, a turbulent fluid layer is separated from a stably stratified one by a relatively sharp but deformable interface. Examples include the convective and radiative zones in stars, the atmospheric convective layer and overlying stratosphere, the Earth's outer core... While motions in the stratified layer are often neglected, it actually supports oscillatory motions called gravito-inertial waves (GIW) excited by Reynolds stresses, entropy fluctuations and interface deformations associated with the turbulence. Besides their direct observation as for instance in asteroseismology, GIW transport energy, carry momentum, break, mix... and are thus essential for accurate models of global climate and solar or core dynamics. Global integrated models including length scales and time scales spanning many orders of magnitude are required to fully address motions in turbulent and stratified zones and to understand the details of the highly non-linear couplings between rotation, meridional circulation, turbulence and waves: this is clearly very challenging from both analytical and numerical points of view. Here, we present results from two complementary laboratory experiments using water as a working fluid and salt or temperature to control the buoyancy effects, allowing to address the whole range of relevant physical issues in simplified models. In the first set-up, we take benefit from the unusual property of water that its density has a maximum value near 4oC to study its convective and oscillatory motions in a tank with a bottom boundary at about 0oC and a hotter upper surface. High precision local measurements of temperature fluctuations are performed simultaneously in the convective and stratified zones to produce the corresponding power density spectrum and probability density function. In the second set-up, a turbulent jet generated by injection of water impinges upon the interface between a uniform density layer and a

  19. Are drivers with CVD more at risk for motor vehicle crashes? Study of men aged 45 to 70.

    PubMed Central

    Guibert, R.; Potvin, L.; Ciampi, A.; Loiselle, J.; Philibert, L.; Franco, E. D.

    1998-01-01

    OBJECTIVE: To examine whether male drivers aged 45 to 70 years suffering from cardiovascular disease (CVD) are more likely to be involved in motor vehicle crashes (MVC) that are reported to the police. DESIGN: Population-based case-control study. SETTING: Data on drivers' ages and medical conditions were compiled from the Societé de l'assurance automobile du Québec's (SAAQ) computerized files. A questionnaire was mailed to all subjects to collect additional information on annual distances driven and various driving behaviours. PARTICIPANTS: Age-stratified population-based random sample. Subjects were 2504 drivers involved in MVCs during a 6-month period; controls were 2520 drivers not involved in crashes. MAIN OUTCOME MEASURES: Proportion of drivers with CVD involved in MVCs. RESULTS: Response rate to the questionnaire was 35.5%. Analysis of the SAAQ files' entire sample of 5024 drivers showed that drivers suffering from CVD were less likely to be involved in MVCs (odds ratio [OR] 0.82, 95% confidence interval [CI] 0.67 to 0.99) than drivers without CVD. Although the estimate of risk remains unchanged when adjusted for age, it becomes statistically insignificant. It also remains unchanged and statistically insignificant when adjusted for yearly distance driven and driver behaviour, as shown by responses to the questionnaire. Drivers suffering from CVD drove significantly less each year (8900 km) than drivers without medical conditions (13,000 km). CONCLUSION: This study shows no increased risk of motor vehicle crashes for drivers suffering from CVD. PMID:9585850

  20. Serum Copper Status in School-Age Children and Pregnant Women in China Nutrition and Health Survey 2010-2012.

    PubMed

    Liu, Xiaobing; Piao, Jianhua; Zhang, Yu; Li, Min; Li, Weidong; Yang, Lichen; Yang, Xiaoguang

    2016-10-01

    Serum copper is an insensitive but reliable biomarker reflecting the change of copper nutritional status in both depleted and replete populations. The current study aimed to establish the reference values of serum copper in school-age children and pregnant women in China and to explore the adequate range of serum copper for both these two categories of people. A multistage, stratified, random sampling combined with probability proportionate to regional size sampling method was employed. A total of 4019 subjects (2736 school-age children and 1283 pregnant women) were selected from China Nutrition and Health Survey 2010-2012 (CNHS 2010-2012). The concentration of serum copper was determined by sector field inductively coupled plasma mass spectrometry (SF-ICP-MS). The adequate range of serum copper was determined by the logistic sigmoid saturation curve of the median derivatives. The median concentration of serum copper was 1140.9 μg/L with a range of 746.7-1677.6 μg/L for school-age children and 1933.4 μg/L with a range of 947.4-3391.4 μg/L for pregnant women. The adequate range of serum copper was 905.7-1440.7 μg/L for school-age children and 1308.8-2537.8 μg/L for pregnant women. These parameters represent an essential prerequisite for the assessment of copper nutritional status, as well as nutrition interventions.

  1. Basic tree-ring sample preparation techniques for aging aspen

    Treesearch

    Lance A. Asherin; Stephen A. Mata

    2001-01-01

    Aspen is notoriously difficult to age because of its light-colored wood and faint annual growth rings. Careful preparation and processing of aspen ring samples can overcome these problems, yield accurate age and growth estimates, and concisely date disturbance events present in the tree-ring record. Proper collection of aspen wood is essential in obtaining usable ring...

  2. Heterotrophic bacterioplankton control on organic and inorganic carbon cycle in stratified and non-stratified lakes of NW Russia

    NASA Astrophysics Data System (ADS)

    Shirokova, Liudmila; Vorobjeva, Taissia; Zabelina, Svetlana; Moreva, Olga; Klimov, Sergey; Shorina, Natalja; Chupakov, Artem; Pokrovsky, Oleg; Audry, Stephan; Viers, Jerome

    2010-05-01

    Lakes of boreal zone regulate the fate of dissolved carbon, nutrients and trace metals during their transport from the watershed to the ocean. Study of primary production - mineralization processes in the context of carbon biogeochemical cycle allows determination of the rate and mechanisms of phytoplankton biomass production and its degradation via aquatic heterotrophic bacteria. In particular, comparative study of vertical distribution of Dissolved Organic Carbon (DOC) in stratified and non-stratified lakes allows establishing the link between biological and chemical aspects of the carbon cycle which, in turns, determines an environmental stability and recovering potential of the entire ecosystem. In order to better understand the biogeochemical mechanisms that control dissolved organic and inorganic carbon migration in surface boreal waters, we studied in 2007-2009 two strongly stratified lakes (15-20 m deep) and two shallow lakes (2-4 m deep) in the Arkhangelsk region (NW Russia, White Sea basin). We conducted natural experiments of the lake water incubation for measurements of the intensity of production/mineralization processes and we determined vertical concentration of DOC during four basic hydrological seasons (winter and summer stratification, and spring and autumn lake overturn). Our seasonal studies of production/mineralization processes demonstrated high intensity of organic matter formation during summer period and significant retard of these processes during winter stagnation. During spring period, there is a strong increase of bacterial destruction of the allochtonous organic matter that is being delivered to the lake via terrigenous input. During autumn overturn, there is a decrease of the activity of phytoplankton, and the degradation of dead biomass by active bacterial community. Organic matter destruction processes are the most active in Svyatoe lake, whereas in the Beloe lake, the rate of organic matter production is significantly higher than

  3. Some design issues of strata-matched non-randomized studies with survival outcomes.

    PubMed

    Mazumdar, Madhu; Tu, Donsheng; Zhou, Xi Kathy

    2006-12-15

    Non-randomized studies for the evaluation of a medical intervention are useful for quantitative hypothesis generation before the initiation of a randomized trial and also when randomized clinical trials are difficult to conduct. A strata-matched non-randomized design is often utilized where subjects treated by a test intervention are matched to a fixed number of subjects treated by a standard intervention within covariate based strata. In this paper, we consider the issue of sample size calculation for this design. Based on the asymptotic formula for the power of a stratified log-rank test, we derive a formula to calculate the minimum number of subjects in the test intervention group that is required to detect a given relative risk between the test and standard interventions. When this minimum number of subjects in the test intervention group is available, an equation is also derived to find the multiple that determines the number of subjects in the standard intervention group within each stratum. The methodology developed is applied to two illustrative examples in gastric cancer and sarcoma.

  4. Electrical stimulation for chronic non-specific low back pain in a working-age population: a 12-week double blinded randomized controlled trial.

    PubMed

    Thiese, Matthew S; Hughes, Matthew; Biggs, Jeremy

    2013-03-28

    Non-invasive electrotherapy is commonly used for treatment of chronic low back pain. Evidence for efficacy of most electrotherapy modalities is weak or lacking. This study aims to execute a high-quality, double-blinded randomized controlled clinical trial comparing 1) H-Wave(®) Device stimulation plus usual care with 2) transcutaneous electrical nerve stimulation (TENS) plus usual care, and 3) Sham electrotherapy plus usual care to determine comparative efficacy for treatment of chronic non-specific low back pain patients. Chronic non-specific low back pain patients between ages of 18-65 years, with pain of at least 3 months duration and minimal current 5/10 VAS pain. Patients will have no significant signs or symptoms of lumbosacral nerve impingement, malignancy, spinal stenosis, or mood disorders. Double blind RCT with 3 arms and 38 subjects per arm. Randomization by permuted blocks of random length, stratified by Workers Compensation claim (yes vs. no), and use of opioids. The null hypothesis of this study is that there are no statistically significant differences in functional improvement between treatment types during and at the end of a 12-week week treatment period. Subjective data will be collected using Filemaker Pro™ database management collection tools. Objective data will be obtained through functional assessments. Data will be collected at enrollment and at 1, 4, 8, and 12 weeks for each participant by a blinded assessor. H-Wave(®) device stimulation (Intervention A) plus usual care, transcutaneous electrical nerve stimulation (TENS) (Intervention B) plus usual care, and sham electrotherapy plus usual care (control). Each treatment arm will have identical numbers of visits (4) and researcher contact time (approximately 15 hours). Oswestry Disability Index. Secondary measures include: Rowland Morris Instrument, VAS pain score, functional evaluation including strength when pushing and pulling, pain free range of motion in flexion and extension

  5. Numerical analysis of internal waves in stratified wake flows

    NASA Astrophysics Data System (ADS)

    Fraunie, Philppe

    2014-05-01

    In laboratory investigations, increased attention has been given to internal waves generated by stationary placed oscillating sources and moving bodies in stratified fluids [1]. The main attention was paid to study flows past bodies of perfect shapes like sphere [2], cylinder [3] of thin strip [3] which are the best theoretical (analytical or numerical) studies. Due to simplicity of geometry, flow around a strip has a potential to investigate separately effects of a drag and lift forces on the body by changing the slope of the horizontally moving strip which can be placed vertically [1], horizontally [2], or be tilted under some angle to the direction of towing velocity [5]. Numeric modeling of a flow past vertical strip uniformly towing with permanent velocity in horizontal direction in a linearly stratified talk which was based on a finite differences solver adapted to the low Reynolds Navier-Stokes equation with transport equation for salinity (LES simulation [6] and RANS [7]) has demonstrated reasonable agreement with data of Schlieren visualization, density marker and probe measurements of internal wave fields. The chosen test cases allowed demonstrating the ability of selected numerical methods to represent stably stratified flows over horizontal strip [4] and hill type 2D obstacles [1, 3] with generation of internal waves. ACKNOWLEDGMENTS This research work was supported by the Region Provence Alpes Côte d'Azur - Modtercom project. The work was also supported by the Russian Foundation for Basic Research (grant 12-01-00128). REFERENCES [1] Chashechkin Yu.D., Mitkin V.V. Experimental study of a fine structure of 2D wakes and mixing past an obstacle in a continuously stratified fluid // Dynamics of Atmosphere and Oceans. 2001. V. 34. P. 165-187. [2] Chashechkin, Yu. D. Hydrodynamics of a sphere in a stratified fluid // Fluid Dyn. 1989. V.24(1) P. 1-7. [3] Mitkin V. V., Chashechkin Yu. D. Transformation of hanging discontinuities into vortex systems in a

  6. Stratified charge rotary engine for general aviation

    NASA Technical Reports Server (NTRS)

    Mount, R. E.; Parente, A. M.; Hady, W. F.

    1986-01-01

    A development history, a current development status assessment, and a design feature and performance capabilities account are given for stratified-charge rotary engines applicable to aircraft propulsion. Such engines are capable of operating on Jet-A fuel with substantial cost savings, improved altitude capability, and lower fuel consumption by comparison with gas turbine powerplants. Attention is given to the current development program of a 400-hp engine scheduled for initial operations in early 1990. Stratified charge rotary engines are also applicable to ground power units, airborne APUs, shipboard generators, and vehicular engines.

  7. Age Differences in Personality: Evidence from a Nationally Representative Australian Sample

    ERIC Educational Resources Information Center

    Lucas, Richard E.; Donnellan, M. Brent

    2009-01-01

    Cross-sectional age differences in the Big Five personality traits were examined in a nationally representative sample of Australians (N = 12,618; age range = 15-84). Extraversion, Neuroticism, and Openness were negatively associated with age, whereas Agreeableness and Conscientiousness were positively associated with age. Effect sizes comparing…

  8. Mortality in perforated peptic ulcer patients after selective management of stratified poor risk cases.

    PubMed

    Rahman, M Mizanur; Islam, M Saiful; Flora, Sabrina; Akhter, S Fariduddin; Hossain, Shahid; Karim, Fazlul

    2007-12-01

    Perforated peptic ulcer disease continues to inflict high morbidity and mortality. Although patients can be stratified according to their surgical risk, optimal management has yet to be described. In this study we demonstrate a treatment option that improves the mortality among critically ill, poor risk patients with perforated peptic ulcer disease. In our study, two series were retrospectively reviewed: group A patients (n = 522) were treated in a single surgical unit at the Dhaka Medical College Hospital, Dhaka, Bangladesh during the 1980s. Among them, 124 patients were stratified as poor risk based on age, delayed presentation, peritoneal contamination, and coexisting medical problems. These criteria were the basis for selecting a group of poor risk patients (n = 84) for minimal surgical intervention (percutaneous peritoneal drainage) out of a larger group of patients, group B (n = 785) treated at Khulna Medical College Hospital during the 1990s. In group A, 479 patients underwent conventional operative management with an operative mortality of 8.97%. Among the 43 deaths, 24 patients were >60 years of age (55.8%), 12 patients had delayed presentation (27.9%), and 7 patients were in shock or had multiple coexisting medical problems (16.2%). In group B, 626 underwent conventional operative management, with 26 deaths at a mortality rate of 4.15%. Altogether, 84 patients were stratified as poor risk and were managed with minimal surgical intervention (percutaneous peritoneal drainage) followed by conservative treatment. Three of these patients died with an operative mortality of 3.5%. Minimal surgical intervention (percutaneous peritoneal drainage) can significantly lower the mortality rate among a selected group of critically ill, poor risk patients with perforated peptic ulcer disease.

  9. Conic Sampling: An Efficient Method for Solving Linear and Quadratic Programming by Randomly Linking Constraints within the Interior

    PubMed Central

    Serang, Oliver

    2012-01-01

    Linear programming (LP) problems are commonly used in analysis and resource allocation, frequently surfacing as approximations to more difficult problems. Existing approaches to LP have been dominated by a small group of methods, and randomized algorithms have not enjoyed popularity in practice. This paper introduces a novel randomized method of solving LP problems by moving along the facets and within the interior of the polytope along rays randomly sampled from the polyhedral cones defined by the bounding constraints. This conic sampling method is then applied to randomly sampled LPs, and its runtime performance is shown to compare favorably to the simplex and primal affine-scaling algorithms, especially on polytopes with certain characteristics. The conic sampling method is then adapted and applied to solve a certain quadratic program, which compute a projection onto a polytope; the proposed method is shown to outperform the proprietary software Mathematica on large, sparse QP problems constructed from mass spectometry-based proteomics. PMID:22952741

  10. Simple-random-sampling-based multiclass text classification algorithm.

    PubMed

    Liu, Wuying; Wang, Lin; Yi, Mianzhu

    2014-01-01

    Multiclass text classification (MTC) is a challenging issue and the corresponding MTC algorithms can be used in many applications. The space-time overhead of the algorithms must be concerned about the era of big data. Through the investigation of the token frequency distribution in a Chinese web document collection, this paper reexamines the power law and proposes a simple-random-sampling-based MTC (SRSMTC) algorithm. Supported by a token level memory to store labeled documents, the SRSMTC algorithm uses a text retrieval approach to solve text classification problems. The experimental results on the TanCorp data set show that SRSMTC algorithm can achieve the state-of-the-art performance at greatly reduced space-time requirements.

  11. Brief assessment of cognition in schizophrenia: normative data in an English-speaking ethnic Chinese sample.

    PubMed

    Eng, Goi Khia; Lam, Max; Bong, Yioe Ling; Subramaniam, Mythily; Bautista, Dianne; Rapisarda, Attilio; Kraus, Michael; Lee, Jimmy; Collinson, Simon Lowes; Chong, Siow Ann; Keefe, Richard S E

    2013-12-01

    There is a dearth of non-Western normative data for neuropsychological batteries designed to measure cognitive deficits in schizophrenia. Here, we provide normative data for English-speaking ethnic Chinese on the widely used Brief Assessment of Cognition in Schizophrenia acquired from 595 healthy community participants between ages 14 and 55. Means and standard deviations of subtests and composite scores were stratified by age group and sex. We also explored linear regression approaches to generate continuous norms adjusted for age, sex, and education. Notable differences in subtest performances were found against a Western comparison sample. Normative data established in the current sample are essential for clinical and research purposes as it serves as a reference source of cognition for ethnic Chinese.

  12. Comparison of exact, efron and breslow parameter approach method on hazard ratio and stratified cox regression model

    NASA Astrophysics Data System (ADS)

    Fatekurohman, Mohamat; Nurmala, Nita; Anggraeni, Dian

    2018-04-01

    Lungs are the most important organ, in the case of respiratory system. Problems related to disorder of the lungs are various, i.e. pneumonia, emphysema, tuberculosis and lung cancer. Comparing all those problems, lung cancer is the most harmful. Considering about that, the aim of this research applies survival analysis and factors affecting the endurance of the lung cancer patient using comparison of exact, Efron and Breslow parameter approach method on hazard ratio and stratified cox regression model. The data applied are based on the medical records of lung cancer patients in Jember Paru-paru hospital on 2016, east java, Indonesia. The factors affecting the endurance of the lung cancer patients can be classified into several criteria, i.e. sex, age, hemoglobin, leukocytes, erythrocytes, sedimentation rate of blood, therapy status, general condition, body weight. The result shows that exact method of stratified cox regression model is better than other. On the other hand, the endurance of the patients is affected by their age and the general conditions.

  13. Response of the elderly to disaster: an age-stratified analysis.

    PubMed

    Bolin, R; Klenow, D J

    This article analyzes the effects of chronological age of disaster victims on their responses to stress effects of natural disasters. Previous research is reviewed and major findings of that research are noted. Findings regarding disaster losses, physical impacts, aid utilization patterns, kinship relations, relative deprivation, social-psychological impacts, neglect of elderly disaster victims, and differential recovery rates by age are retested on new data. Data described herein were gathered using survey techniques in two disaster stricken communities in Texas. Elderly victims' responses to the tornadoes are compared to a nonelderly (under sixty years of age) group to assess differences. Findings of previous research were, in many instances, supported although certain divergences between the current findings and preceding findings are noted, particularly in rates of recovery.

  14. Do age and gender contribute to workers' burnout symptoms?

    PubMed

    Marchand, A; Blanc, M-E; Beauregard, N

    2018-06-15

    Despite mounting evidence on the association between work stress and burnout, there is limited knowledge about the extent to which workers' age and gender are associated with burnout. To evaluate the relationship between age, gender and their interaction with burnout in a sample of Canadian workers. Data were collected in 2009-12 from a sample of 2073 Canadian workers from 63 workplaces in the province of Quebec. Data were analysed with multilevel regression models to test for linear and non-linear relationships between age and burnout. Analyses adjusted for marital status, parental status, educational level and number of working hours were conducted on the total sample and stratified by gender. Data were collected from a sample of 2073 Canadian workers (response rate 73%). Age followed a non-linear relationship with emotional exhaustion and total burnout, while it was linearly related to cynicism and reduced professional efficacy. Burnout level reduced with increasing age in men, but the association was bimodal in women, with women aged between 20-35 and over 55 years showing the highest burnout level. These results suggest that burnout symptoms varied greatly according to different life stages of working men and women. Younger men, and women aged between 20-35 and 55 years and over are particularly susceptible and should be targeted for programmes to reduce risk of burnout.

  15. Sexual activity, fertility and contraceptive use in middle-aged and older men: Men in Australia, Telephone Survey (MATeS).

    PubMed

    Holden, C A; McLachlan, R I; Cumming, R; Wittert, G; Handelsman, D J; de Kretser, D M; Pitts, M

    2005-12-01

    With limited information regarding fertility and sexual activity in the older population, men's behaviour, attitudes and concerns were explored in a representative population of middle-aged and older men using the Men in Australia, Telephone Survey (MATeS). A stratified random national sample of 5990 men participated in a standardized computer-assisted telephone interview. Equal numbers in the age strata 40-49, 50-59, 60-69 and >or=70 years were surveyed with findings census-standardized to the national population. Broad aspects of men's health and well-being, including reproductive health, were explored. The majority of men were sexually active in the last 12 months (age-standardized proportion, 78.3%) with approximately 37% of men aged >or=70 years still continuing sexual activity. Overall, 12.2% of men had never fathered children, of whom most (7.7%) had chosen not to have children. Questioning on failed attempts to produce a pregnancy suggested an involuntary infertility rate of 7.6%. The age-standardized vasectomy rate was 25.1%, with 5.6% of vasectomized men having no children. Although 9.2% of vasectomized men regretted sterilization, only 1.4% had undergone vasectomy reversal. Continuing sexual activity, fertility and contraception needs in middle-aged and older men suggests that education and service delivery must be more appropriately directed to an ageing population.

  16. Genome-wide meta-analyses of stratified depression in Generation Scotland and UK Biobank.

    PubMed

    Hall, Lynsey S; Adams, Mark J; Arnau-Soler, Aleix; Clarke, Toni-Kim; Howard, David M; Zeng, Yanni; Davies, Gail; Hagenaars, Saskia P; Maria Fernandez-Pujals, Ana; Gibson, Jude; Wigmore, Eleanor M; Boutin, Thibaud S; Hayward, Caroline; Scotland, Generation; Porteous, David J; Deary, Ian J; Thomson, Pippa A; Haley, Chris S; McIntosh, Andrew M

    2018-01-10

    Few replicable genetic associations for Major Depressive Disorder (MDD) have been identified. Recent studies of MDD have identified common risk variants by using a broader phenotype definition in very large samples, or by reducing phenotypic and ancestral heterogeneity. We sought to ascertain whether it is more informative to maximize the sample size using data from all available cases and controls, or to use a sex or recurrent stratified subset of affected individuals. To test this, we compared heritability estimates, genetic correlation with other traits, variance explained by MDD polygenic score, and variants identified by genome-wide meta-analysis for broad and narrow MDD classifications in two large British cohorts - Generation Scotland and UK Biobank. Genome-wide meta-analysis of MDD in males yielded one genome-wide significant locus on 3p22.3, with three genes in this region (CRTAP, GLB1, and TMPPE) demonstrating a significant association in gene-based tests. Meta-analyzed MDD, recurrent MDD and female MDD yielded equivalent heritability estimates, showed no detectable difference in association with polygenic scores, and were each genetically correlated with six health-correlated traits (neuroticism, depressive symptoms, subjective well-being, MDD, a cross-disorder phenotype and Bipolar Disorder). Whilst stratified GWAS analysis revealed a genome-wide significant locus for male MDD, the lack of independent replication, and the consistent pattern of results in other MDD classifications suggests that phenotypic stratification using recurrence or sex in currently available sample sizes is currently weakly justified. Based upon existing studies and our findings, the strategy of maximizing sample sizes is likely to provide the greater gain.

  17. Trajectories of Familism Values and the Prosocial Tendencies of Mexican American Adolescents

    ERIC Educational Resources Information Center

    Knight, George P.; Mazza, Gina L.; Carlo, Gustavo

    2018-01-01

    We examined how the development of familism values from 5th to 10th grade relates to 12th-grade prosocial tendencies (after controlling for 10th-grade prosocial tendencies) using a stratified random sample of 749 Mexican American adolescents (M = 10.42 years of age at 5th grade; 48.9% girls) from 35 culturally and economically diverse…

  18. Do Children Who Bully Their Peers Also Play Violent Video Games? A Canadian National Study

    ERIC Educational Resources Information Center

    Dittrick, Crystal J.; Beran, Tanya N.; Mishna, Faye; Hetherington, Ross; Shariff, Shaheen

    2013-01-01

    The study examined whether children who bully others are likely to prefer playing video games that are rated high in maturity and violence. A stratified random sample of Canadian children ages 10 to 17 years from the provinces of Canada was obtained. Parents (n = 397) and their children (n = 492) completed an online survey of children's bullying…

  19. Background oriented schlieren in a density stratified fluid.

    PubMed

    Verso, Lilly; Liberzon, Alex

    2015-10-01

    Non-intrusive quantitative fluid density measurement methods are essential in the stratified flow experiments. Digital imaging leads to synthetic schlieren methods in which the variations of the index of refraction are reconstructed computationally. In this study, an extension to one of these methods, called background oriented schlieren, is proposed. The extension enables an accurate reconstruction of the density field in stratified liquid experiments. Typically, the experiments are performed by the light source, background pattern, and the camera positioned on the opposite sides of a transparent vessel. The multimedia imaging through air-glass-water-glass-air leads to an additional aberration that destroys the reconstruction. A two-step calibration and image remapping transform are the key components that correct the images through the stratified media and provide a non-intrusive full-field density measurements of transparent liquids.

  20. A Comparison of Single Sample and Bootstrap Methods to Assess Mediation in Cluster Randomized Trials

    ERIC Educational Resources Information Center

    Pituch, Keenan A.; Stapleton, Laura M.; Kang, Joo Youn

    2006-01-01

    A Monte Carlo study examined the statistical performance of single sample and bootstrap methods that can be used to test and form confidence interval estimates of indirect effects in two cluster randomized experimental designs. The designs were similar in that they featured random assignment of clusters to one of two treatment conditions and…

  1. The systematic component of phylogenetic error as a function of taxonomic sampling under parsimony.

    PubMed

    Debry, Ronald W

    2005-06-01

    The effect of taxonomic sampling on phylogenetic accuracy under parsimony is examined by simulating nucleotide sequence evolution. Random error is minimized by using very large numbers of simulated characters. This allows estimation of the consistency behavior of parsimony, even for trees with up to 100 taxa. Data were simulated on 8 distinct 100-taxon model trees and analyzed as stratified subsets containing either 25 or 50 taxa, in addition to the full 100-taxon data set. Overall accuracy decreased in a majority of cases when taxa were added. However, the magnitude of change in the cases in which accuracy increased was larger than the magnitude of change in the cases in which accuracy decreased, so, on average, overall accuracy increased as more taxa were included. A stratified sampling scheme was used to assess accuracy for an initial subsample of 25 taxa. The 25-taxon analyses were compared to 50- and 100-taxon analyses that were pruned to include only the original 25 taxa. On average, accuracy for the 25 taxa was improved by taxon addition, but there was considerable variation in the degree of improvement among the model trees and across different rates of substitution.

  2. Predictors of depressive symptoms in older Japanese primiparas at 1 month post-partum: A risk-stratified analysis.

    PubMed

    Iwata, Hiroko; Mori, Emi; Tsuchiya, Miyako; Sakajo, Akiko; Maehara, Kunie; Ozawa, Harumi; Morita, Akiko; Maekawa, Tomoko; Aoki, Kyoko; Tamakoshi, Koji

    2016-01-01

    Older maternal age has become more common in Japan. Studies suggest that older maternal age and primiparity are associated with post-partum depression. The present study aimed to identify predictors of post-partum depression in older Japanese primiparas at 1 month post-partum. Participants were 479 primiparas aged 35 years and over, drawn from a prospective cohort study. Data were collected using self-report questionnaires. Depression was measured with the Japanese version of the Edinburgh Postnatal Depression Scale. Stepwise logistic regression analysis was conducted on binary outcome variables of depression at 1 month post-partum, along with a stratified analysis based on the risk status of depression. Five predictors were identified: (i) the depression score during hospital stay; (ii) financial burden; (iii) dissatisfaction with appraisal support; (iv) physical burden in daily life; and (v) concerns about infant caretaking. Stratified analysis identified dissatisfaction with instrumental support in the low-risk group, and the Child-care Value Scale score as unique predictors in the high-risk group. These results highlight the importance of early assessment of depressive symptoms and the provision of continuous care. © 2015 Japan Academy of Nursing Science.

  3. Reaching the Hard-to-Reach: A Probability Sampling Method for Assessing Prevalence of Driving under the Influence after Drinking in Alcohol Outlets

    PubMed Central

    De Boni, Raquel; do Nascimento Silva, Pedro Luis; Bastos, Francisco Inácio; Pechansky, Flavio; de Vasconcellos, Mauricio Teixeira Leite

    2012-01-01

    Drinking alcoholic beverages in places such as bars and clubs may be associated with harmful consequences such as violence and impaired driving. However, methods for obtaining probabilistic samples of drivers who drink at these places remain a challenge – since there is no a priori information on this mobile population – and must be continually improved. This paper describes the procedures adopted in the selection of a population-based sample of drivers who drank at alcohol selling outlets in Porto Alegre, Brazil, which we used to estimate the prevalence of intention to drive under the influence of alcohol. The sampling strategy comprises a stratified three-stage cluster sampling: 1) census enumeration areas (CEA) were stratified by alcohol outlets (AO) density and sampled with probability proportional to the number of AOs in each CEA; 2) combinations of outlets and shifts (COS) were stratified by prevalence of alcohol-related traffic crashes and sampled with probability proportional to their squared duration in hours; and, 3) drivers who drank at the selected COS were stratified by their intention to drive and sampled using inverse sampling. Sample weights were calibrated using a post-stratification estimator. 3,118 individuals were approached and 683 drivers interviewed, leading to an estimate that 56.3% (SE = 3,5%) of the drivers intended to drive after drinking in less than one hour after the interview. Prevalence was also estimated by sex and broad age groups. The combined use of stratification and inverse sampling enabled a good trade-off between resource and time allocation, while preserving the ability to generalize the findings. The current strategy can be viewed as a step forward in the efforts to improve surveys and estimation for hard-to-reach, mobile populations. PMID:22514620

  4. Report for Colorado: Background & Visuals, Math 2005. The Nation's Report Card

    ERIC Educational Resources Information Center

    Sandoval, Pam A.

    2005-01-01

    The National Assessment of Educational Progress (NAEP) 2005 assessment was administered to a stratified random sample of fourth-, eighth-, and twelfth-graders at the national level and to a stratified random sample of fourth- and eighth-graders at the state level. The Mathematics Framework for NAEP was revised in 1996 and again in 2005. The new…

  5. Growth and tolerance of formula with lactoferrin in infants through one year of age: double-blind, randomized, controlled trial.

    PubMed

    Johnston, William H; Ashley, Claude; Yeiser, Michael; Harris, Cheryl L; Stolz, Suzanne I; Wampler, Jennifer L; Wittke, Anja; Cooper, Timothy R

    2015-11-07

    Human milk provides necessary macronutrients (protein, carbohydrate, fat) required for infant nutrition. Lactoferrin (Lf), a multifunctional iron-binding protein predominant in human milk, shares similar protein sequence, structure, and bioactivity with bovine Lf (bLf). This large-scale pediatric nutrition study was designed to evaluate growth and tolerance in healthy infants who received study formulas with bLf at concentrations within the range of mature human milk. In this multi-center, double-blind, parallel-designed, gender-stratified prospective study 480 infants were randomized to receive a marketed routine cow's milk-based infant formula (Control; n = 155) or one of two investigational formulas with bLf at 0.6 g/L (LF-0.6; n = 165) or 1.0 g/L (LF-1.0; n = 160) from 14-365 days of age. Investigational formulas also had a prebiotic blend of polydextrose (PDX) and galactooligosaccharides (GOS) and adjusted arachidonic acid (ARA). The primary outcome was weight growth rate from 14-120 days of age. Anthropometric measurements were taken at 14, 30, 60, 90, 120, 180, 275, and 365 days of age. Parental recall of formula intake, tolerance, and stool characteristics was collected at each time point. Medically-confirmed adverse events were collected throughout the study period. There were no group differences in growth rate (g/day) from 14-120 days of age; 353 infants completed the study through 365 days of age ( 110; LF-0.6: 127; LF-1.0: 116). Few differences in growth, formula intake, and infant fussiness or gassiness were observed through 365 day of age. Group discontinuation rates and the overall group incidence of medically-confirmed adverse events were not significantly different. From 30 through 180 days of age, group differences in stool consistency (P < 0.005) were detected with softer stools for infants in the LF-0.6 and LF-1.0 groups versus CONTROL. Compared to the Control, infants who received investigational formulas with bLf and the

  6. Comparison of sampling methods for hard-to-reach francophone populations: yield and adequacy of advertisement and respondent-driven sampling.

    PubMed

    Ngwakongnwi, Emmanuel; King-Shier, Kathryn M; Hemmelgarn, Brenda R; Musto, Richard; Quan, Hude

    2014-01-01

    Francophones who live outside the primarily French-speaking province of Quebec, Canada, risk being excluded from research by lack of a sampling frame. We examined the adequacy of random sampling, advertising, and respondent-driven sampling for recruitment of francophones for survey research. We recruited francophones residing in the city of Calgary, Alberta, through advertising and respondentdriven sampling. These 2 samples were then compared with a random subsample of Calgary francophones derived from the 2006 Canadian Community Health Survey (CCHS). We assessed the effectiveness of advertising and respondent-driven sampling in relation to the CCHS sample by comparing demographic characteristics and selected items from the CCHS (specifically self-reported general health status, perceived weight, and having a family doctor). We recruited 120 francophones through advertising and 145 through respondent-driven sampling; the random sample from the CCHS consisted of 259 records. The samples derived from advertising and respondentdriven sampling differed from the CCHS in terms of age (mean ages 41.0, 37.6, and 42.5 years, respectively), sex (proportion of males 26.1%, 40.6%, and 56.6%, respectively), education (college or higher 86.7% , 77.9% , and 59.1%, respectively), place of birth (immigrants accounting for 45.8%, 55.2%, and 3.7%, respectively), and not having a regular medical doctor (16.7%, 34.5%, and 16.6%, respectively). Differences were not tested statistically because of limitations on the analysis of CCHS data imposed by Statistics Canada. The samples generated exclusively through advertising and respondent-driven sampling were not representative of the gold standard sample from the CCHS. Use of such biased samples for research studies could generate misleading results.

  7. The relationships between sex hormones and sexual function in middle-aged and older European men.

    PubMed

    O'Connor, Daryl B; Lee, David M; Corona, Giovanni; Forti, Gianni; Tajar, Abdelouahid; O'Neill, Terence W; Pendleton, Neil; Bartfai, Gyorgy; Boonen, Steven; Casanueva, Felipe F; Finn, Joseph D; Giwercman, Aleksander; Han, Thang S; Huhtaniemi, Ilpo T; Kula, Krzysztof; Labrie, Fernand; Lean, Michael E J; Punab, Margus; Silman, Alan J; Vanderschueren, Dirk; Wu, Frederick C W

    2011-10-01

    Limited data are available exploring the associations between sex hormones, multiple domains of sexual functioning, and sexual function-related distress in nonpatient samples in Europe. The aim of the study was to investigate the relationships between serum testosterone (T), estradiol (E2), and dihydrotestosterone (DHT) and sexual function in a multicenter population-based study of aging in men. Using stratified random sampling, 2838 men aged 40-79 yr completed the European Male Ageing Study-Sexual Function Questionnaire and provided a blood sample for hormone measurements. T, E2, and DHT were measured using gas chromatography-mass spectrometry. We conducted a community-based population survey in eight European centers. Self-reported sexual function (overall sexual function, sexual function-related distress, erectile dysfunction, masturbation) was measured. Total and free T, but not E2 or DHT, was associated with overall sexual function in middle-aged and older men. E2 was the only hormone associated with sexual function-related distress such that higher levels were related to greater distress. Free T levels were associated with masturbation frequency and erectile dysfunction in the fully adjusted models, such that higher T was associated with less dysfunction and greater frequency. Moreover, there was a T threshold for the relationship between total T, sexual function, and erectile dysfunction. At T concentrations of 8 nmol/liter or less, T was associated with worse sexual functioning, whereas at T levels over 8 nmol/liter, the relationship came to a plateau. These findings suggest that different hormonal mechanisms may regulate sexual functioning (T) vs. the psychological aspects (E2) of male sexual behavior. Moreover, there was a T threshold for overall sexual function such that at levels greater than 8 nmol/liter the relationship between T and sexual function did not become stronger.

  8. Jet-mixing of initially-stratified liquid-liquid pipe flows: experiments and numerical simulations

    NASA Astrophysics Data System (ADS)

    Wright, Stuart; Ibarra-Hernandes, Roberto; Xie, Zhihua; Markides, Christos; Matar, Omar

    2016-11-01

    Low pipeline velocities lead to stratification and so-called 'phase slip' in horizontal liquid-liquid flows due to differences in liquid densities and viscosities. Stratified flows have no suitable single point for sampling, from which average phase properties (e.g. fractions) can be established. Inline mixing, achieved by static mixers or jets in cross-flow (JICF), is often used to overcome liquid-liquid stratification by establishing unstable two-phase dispersions for sampling. Achieving dispersions in liquid-liquid pipeline flows using JICF is the subject of this experimental and modelling work. The experimental facility involves a matched refractive index liquid-liquid-solid system, featuring an ETFE test section, and experimental liquids which are silicone oil and a 51-wt% glycerol solution. The matching then allows the dispersed fluid phase fractions and velocity fields to be established through advanced optical techniques, namely PLIF (for phase) and PTV or PIV (for velocity fields). CFD codes using the volume of a fluid (VOF) method are then used to demonstrate JICF breakup and dispersion in stratified pipeline flows. A number of simple jet configurations are described and their dispersion effectiveness is compared with the experimental results. Funding from Cameron for Ph.D. studentship (SW) gratefully acknowledged.

  9. Job strain and blood pressure in employed men and women: a pooled analysis of four northern italian population samples.

    PubMed

    Cesana, Giancarlo; Sega, Roberto; Ferrario, Marco; Chiodini, Paolo; Corrao, Giovanni; Mancia, Giuseppe

    2003-01-01

    The extent to which psychosocial stress concurs to raise blood pressure is still uncertain. Here the association between job strain and office blood pressure in a pooled analysis of four population samples from northern Italy is assessed. Four surveys assessing prevalence of major coronary risk factors were performed in 1986, 1990, 1991, and 1993 in area "Brianza" (Milan), a World Health Organization-MONItoring cardiovascular disease (WHO-MONICA) Project collaborating center. Ten year age- and gender-stratified independent samples were randomly recruited from the 25- to 64-year-old residents. The methods used to assess coronary risk factors strictly adhered to the MONICA manual, were kept constant, and underwent internal and external quality controls. Job strain was investigated through the administration to employed participants of a questionnaire derived from the Karasek model, assessing job demand/control latitude. Analysis was restricted to 25- to 54-year-old participants, untreated for hypertension (1799 men and 1010 women). Among men, there was a 3 mm Hg increase of systolic blood pressure (p<.001) moving from low to high strain job categories. This difference was independent from age, education, body mass index, alcohol intake, smoking habits, leisure time physical activity, and survey. No relevant differences among job strain categories were found in women and for diastolic blood pressure in both gender groups. These results carried out on a large population-based sample confirm previous findings obtained adopting ambulatory blood pressure measurements in more restricted samples of population or patients. Further research is needed to clarify the relationship between perceived work stress and blood pressure in women.

  10. Age-related differences in factors associated with cervical spine injuries in children.

    PubMed

    Leonard, Julie C; Jaffe, David M; Olsen, Cody S; Kuppermann, Nathan

    2015-04-01

    The Pediatric Emergency Care Applied Research Network (PECARN) investigators previously identified risk factors associated with cervical spine injuries (CSIs) in children. Anatomic maturation and age-related variation in mechanisms of injury suggested the need to explore factors separately for younger versus older children. The purpose of this substudy was to investigate CSI risk factors in age subgroups within the PECARN study cohort. This was an age-stratified case-control analysis of children younger than 16 years presenting to 17 PECARN hospitals following blunt trauma between January 1, 2000 and December 31, 2004. Data were abstracted for children with CSIs and randomly selected CSI-free children. Age-stratified multivariable logistic regression was performed to identify factors associated with CSI within three age groups: younger than 2, 2 to 7, and 8 to 15 years. Sensitivity and specificity for CSI were estimated for both the age-specific and original (altered mental status, focal neurologic findings, neck pain, torticollis, substantial torso injury, predisposing conditions, diving, and high-risk motor vehicle crash [MVC]) models. Among 540 children with CSIs, 27 were younger than 2 years, 140 were 2 to 7 years, and 373 were 8 to 15 years. Focal neurologic deficits and high-risk MVC were associated with CSIs in all age-specific models. Other age-specific factors included the following: younger than 2 years, none; 2 to 7 years, altered mental status, neck pain, torticollis; and 8 to 15 years, altered mental status, neck pain, diving. Age-specific models had comparable sensitivity to the original model among the older groups, but had lower sensitivity and higher specificity among the youngest children. While this analysis supports the original PECARN model for CSI, there were subtle age variations in factors associated with CSIs in children that warrant future investigation. © 2015 by the Society for Academic Emergency Medicine.

  11. Random regression analyses using B-splines functions to model growth from birth to adult age in Canchim cattle.

    PubMed

    Baldi, F; Alencar, M M; Albuquerque, L G

    2010-12-01

    The objective of this work was to estimate covariance functions using random regression models on B-splines functions of animal age, for weights from birth to adult age in Canchim cattle. Data comprised 49,011 records on 2435 females. The model of analysis included fixed effects of contemporary groups, age of dam as quadratic covariable and the population mean trend taken into account by a cubic regression on orthogonal polynomials of animal age. Residual variances were modelled through a step function with four classes. The direct and maternal additive genetic effects, and animal and maternal permanent environmental effects were included as random effects in the model. A total of seventeen analyses, considering linear, quadratic and cubic B-splines functions and up to seven knots, were carried out. B-spline functions of the same order were considered for all random effects. Random regression models on B-splines functions were compared to a random regression model on Legendre polynomials and with a multitrait model. Results from different models of analyses were compared using the REML form of the Akaike Information criterion and Schwarz' Bayesian Information criterion. In addition, the variance components and genetic parameters estimated for each random regression model were also used as criteria to choose the most adequate model to describe the covariance structure of the data. A model fitting quadratic B-splines, with four knots or three segments for direct additive genetic effect and animal permanent environmental effect and two knots for maternal additive genetic effect and maternal permanent environmental effect, was the most adequate to describe the covariance structure of the data. Random regression models using B-spline functions as base functions fitted the data better than Legendre polynomials, especially at mature ages, but higher number of parameters need to be estimated with B-splines functions. © 2010 Blackwell Verlag GmbH.

  12. Synthesizing Information From Language Samples and Standardized Tests in School-Age Bilingual Assessment

    PubMed Central

    Pham, Giang

    2017-01-01

    Purpose Although language samples and standardized tests are regularly used in assessment, few studies provide clinical guidance on how to synthesize information from these testing tools. This study extends previous work on the relations between tests and language samples to a new population—school-age bilingual speakers with primary language impairment—and considers the clinical implications for bilingual assessment. Method Fifty-one bilingual children with primary language impairment completed narrative language samples and standardized language tests in English and Spanish. Children were separated into younger (ages 5;6 [years;months]–8;11) and older (ages 9;0–11;2) groups. Analysis included correlations with age and partial correlations between language sample measures and test scores in each language. Results Within the younger group, positive correlations with large effect sizes indicated convergence between test scores and microstructural language sample measures in both Spanish and English. There were minimal correlations in the older group for either language. Age related to English but not Spanish measures. Conclusions Tests and language samples complement each other in assessment. Wordless picture-book narratives may be more appropriate for ages 5–8 than for older children. We discuss clinical implications, including a case example of a bilingual child with primary language impairment, to illustrate how to synthesize information from these tools in assessment. PMID:28055056

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

    EPA Science Inventory

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

  14. The Dirichlet-Multinomial Model for Multivariate Randomized Response Data and Small Samples

    ERIC Educational Resources Information Center

    Avetisyan, Marianna; Fox, Jean-Paul

    2012-01-01

    In survey sampling the randomized response (RR) technique can be used to obtain truthful answers to sensitive questions. Although the individual answers are masked due to the RR technique, individual (sensitive) response rates can be estimated when observing multivariate response data. The beta-binomial model for binary RR data will be generalized…

  15. Does sampling using random digit dialling really cost more than sampling from telephone directories: Debunking the myths

    PubMed Central

    Yang, Baohui; Eyeson-Annan, Margo

    2006-01-01

    Background Computer assisted telephone interviewing (CATI) is widely used for health surveys. The advantages of CATI over face-to-face interviewing are timeliness and cost reduction to achieve the same sample size and geographical coverage. Two major CATI sampling procedures are used: sampling directly from the electronic white pages (EWP) telephone directory and list assisted random digit dialling (LA-RDD) sampling. EWP sampling covers telephone numbers of households listed in the printed white pages. LA-RDD sampling has a better coverage of households than EWP sampling but is considered to be more expensive due to interviewers dialling more out-of-scope numbers. Methods This study compared an EWP sample and a LA-RDD sample from the New South Wales Population Health Survey in 2003 on demographic profiles, health estimates, coefficients of variation in weights, design effects on estimates, and cost effectiveness, on the basis of achieving the same level of precision of estimates. Results The LA-RDD sample better represented the population than the EWP sample, with a coefficient of variation of weights of 1.03 for LA-RDD compared with 1.21 for EWP, and average design effects of 2.00 for LA-RDD compared with 2.38 for EWP. Also, a LA-RDD sample can save up to 14.2% in cost compared to an EWP sample to achieve the same precision for health estimates. Conclusion A LA-RDD sample better represents the population, which potentially leads to reduced bias in health estimates, and rather than costing more than EWP actually costs less. PMID:16504117

  16. Analysis of the machinery and intermediates of the 5hmC-mediated DNA demethylation pathway in aging on samples from the MARK-AGE Study.

    PubMed

    Valentini, Elisabetta; Zampieri, Michele; Malavolta, Marco; Bacalini, Maria Giulia; Calabrese, Roberta; Guastafierro, Tiziana; Reale, Anna; Franceschi, Claudio; Hervonen, Antti; Koller, Bernhard; Bernhardt, Jürgen; Slagboom, P Eline; Toussaint, Olivier; Sikora, Ewa; Gonos, Efstathios S; Breusing, Nicolle; Grune, Tilman; Jansen, Eugène; Dollé, Martijn E T; Moreno-Villanueva, María; Sindlinger, Thilo; Bürkle, Alexander; Ciccarone, Fabio; Caiafa, Paola

    2016-08-29

    Gradual changes in the DNA methylation landscape occur throughout aging virtually in all human tissues. A widespread reduction of 5-methylcytosine (5mC), associated with highly reproducible site-specific hypermethylation, characterizes the genome in aging. Therefore, an equilibrium seems to exist between general and directional deregulating events concerning DNA methylation controllers, which may underpin the age-related epigenetic changes. In this context, 5mC-hydroxylases (TET enzymes) are new potential players. In fact, TETs catalyze the stepwise oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), driving the DNA demethylation process based on thymine DNA glycosylase (TDG)-mediated DNA repair pathway. The present paper reports the expression of DNA hydroxymethylation components, the levels of 5hmC and of its derivatives in peripheral blood mononuclear cells of age-stratified donors recruited in several European countries in the context of the EU Project 'MARK-AGE'. The results provide evidence for an age-related decline of TET1 , TET3 and TDG gene expression along with a decrease of 5hmC and an accumulation of 5caC. These associations were independent of confounding variables, including recruitment center, gender and leukocyte composition. The observed impairment of 5hmC-mediated DNA demethylation pathway in blood cells may lead to aberrant transcriptional programs in the elderly.

  17. Does the Aging Process Significantly Modify the Mean Heart Rate?

    PubMed Central

    Santos, Marcos Antonio Almeida; Sousa, Antonio Carlos Sobral; Reis, Francisco Prado; Santos, Thayná Ramos; Lima, Sonia Oliveira; Barreto-Filho, José Augusto

    2013-01-01

    Background The Mean Heart Rate (MHR) tends to decrease with age. When adjusted for gender and diseases, the magnitude of this effect is unclear. Objective To analyze the MHR in a stratified sample of active and functionally independent individuals. Methods A total of 1,172 patients aged ≥ 40 years underwent Holter monitoring and were stratified by age group: 1 = 40-49, 2 = 50-59, 3 = 60-69, 4 = 70-79, 5 = ≥ 80 years. The MHR was evaluated according to age and gender, adjusted for Hypertension (SAH), dyslipidemia and non-insulin dependent diabetes mellitus (NIDDM). Several models of ANOVA, correlation and linear regression were employed. A two-tailed p value <0.05 was considered significant (95% CI). Results The MHR tended to decrease with the age range: 1 = 77.20 ± 7.10; 2 = 76.66 ± 7.07; 3 = 74.02 ± 7.46; 4 = 72.93 ± 7.35; 5 = 73.41 ± 7.98 (p < 0.001). Women showed a correlation with higher MHR (p <0.001). In the ANOVA and regression models, age and gender were predictors (p < 0.001). However, R2 and ETA2 < 0.10, as well as discrete standardized beta coefficients indicated reduced effect. Dyslipidemia, hypertension and DM did not influence the findings. Conclusion The MHR decreased with age. Women had higher values of MHR, regardless of the age group. Correlations between MHR and age or gender, albeit significant, showed the effect magnitude had little statistical relevance. The prevalence of SAH, dyslipidemia and diabetes mellitus did not influence the results. PMID:24029962

  18. Simulation model of stratified thermal energy storage tank using finite difference method

    NASA Astrophysics Data System (ADS)

    Waluyo, Joko

    2016-06-01

    Stratified TES tank is normally used in the cogeneration plant. The stratified TES tanks are simple, low cost, and equal or superior in thermal performance. The advantage of TES tank is that it enables shifting of energy usage from off-peak demand for on-peak demand requirement. To increase energy utilization in a stratified TES tank, it is required to build a simulation model which capable to simulate the charging phenomenon in the stratified TES tank precisely. This paper is aimed to develop a novel model in addressing the aforementioned problem. The model incorporated chiller into the charging of stratified TES tank system in a closed system. The model was developed in one-dimensional type involve with heat transfer aspect. The model covers the main factors affect to degradation of temperature distribution namely conduction through the tank wall, conduction between cool and warm water, mixing effect on the initial flow of the charging as well as heat loss to surrounding. The simulation model is developed based on finite difference method utilizing buffer concept theory and solved in explicit method. Validation of the simulation model is carried out using observed data obtained from operating stratified TES tank in cogeneration plant. The temperature distribution of the model capable of representing S-curve pattern as well as simulating decreased charging temperature after reaching full condition. The coefficient of determination values between the observed data and model obtained higher than 0.88. Meaning that the model has capability in simulating the charging phenomenon in the stratified TES tank. The model is not only capable of generating temperature distribution but also can be enhanced for representing transient condition during the charging of stratified TES tank. This successful model can be addressed for solving the limitation temperature occurs in charging of the stratified TES tank with the absorption chiller. Further, the stratified TES tank can be

  19. A randomized trial of survey participation in a national random sample of general practitioners and gynecologists in France.

    PubMed

    Legleye, S; Bohet, A; Razafindratsima, N; Bajos, N; Moreau, C

    2014-08-01

    Healthcare professionals play a critical role in women's choice of contraceptive methods. However, national surveys on sexual and reproductive health (SRH) among physicians are rare and present low participation rates. We conducted a randomized trial to test for the effectiveness of three interventions to improve survey participation of private physicians delivering reproductive health services in France. The study comprised a national random sample of 500 general practitioners and 500 gynecologists working in private offices. All received a postal invitation to participate either by completing a paper, phone or online questionnaire. Physicians were randomly assigned to six groups to test for the effect of three interventions: a non-monetary incentive in the form of a scientific book, telephone contact, and the possibility of completing the questionnaire by phone. Overall, 362 questionnaires were collected (26 online, 2 by phone) and 58 physicians were ineligible. The completion rate increased from 26.7% in physicians who received no intervention to 42.7% in those who received the book and a phone call. The phone call increased the completion rate by 11% percentage points (P=0.01), while the book had no significant effect. Results from multivariate logistic regressions also indicate that gynecologists (OR=1.6) and female physicians (OR=1.5) were more likely to participate than others. The results suggest that phone calls substantially increase participation of physicians in sexual and reproductive health surveys but have little impact on sampling distortion. Differentials in response rates by physicians' characteristics should be considered in future SRH studies among physicians. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  20. Implications of sampling design and sample size for national carbon accounting systems.

    PubMed

    Köhl, Michael; Lister, Andrew; Scott, Charles T; Baldauf, Thomas; Plugge, Daniel

    2011-11-08

    Countries willing to adopt a REDD regime need to establish a national Measurement, Reporting and Verification (MRV) system that provides information on forest carbon stocks and carbon stock changes. Due to the extensive areas covered by forests the information is generally obtained by sample based surveys. Most operational sampling approaches utilize a combination of earth-observation data and in-situ field assessments as data sources. We compared the cost-efficiency of four different sampling design alternatives (simple random sampling, regression estimators, stratified sampling, 2-phase sampling with regression estimators) that have been proposed in the scope of REDD. Three of the design alternatives provide for a combination of in-situ and earth-observation data. Under different settings of remote sensing coverage, cost per field plot, cost of remote sensing imagery, correlation between attributes quantified in remote sensing and field data, as well as population variability and the percent standard error over total survey cost was calculated. The cost-efficiency of forest carbon stock assessments is driven by the sampling design chosen. Our results indicate that the cost of remote sensing imagery is decisive for the cost-efficiency of a sampling design. The variability of the sample population impairs cost-efficiency, but does not reverse the pattern of cost-efficiency of the individual design alternatives. Our results clearly indicate that it is important to consider cost-efficiency in the development of forest carbon stock assessments and the selection of remote sensing techniques. The development of MRV-systems for REDD need to be based on a sound optimization process that compares different data sources and sampling designs with respect to their cost-efficiency. This helps to reduce the uncertainties related with the quantification of carbon stocks and to increase the financial benefits from adopting a REDD regime.

  1. Sample size determination for GEE analyses of stepped wedge cluster randomized trials.

    PubMed

    Li, Fan; Turner, Elizabeth L; Preisser, John S

    2018-06-19

    In stepped wedge cluster randomized trials, intact clusters of individuals switch from control to intervention from a randomly assigned period onwards. Such trials are becoming increasingly popular in health services research. When a closed cohort is recruited from each cluster for longitudinal follow-up, proper sample size calculation should account for three distinct types of intraclass correlations: the within-period, the inter-period, and the within-individual correlations. Setting the latter two correlation parameters to be equal accommodates cross-sectional designs. We propose sample size procedures for continuous and binary responses within the framework of generalized estimating equations that employ a block exchangeable within-cluster correlation structure defined from the distinct correlation types. For continuous responses, we show that the intraclass correlations affect power only through two eigenvalues of the correlation matrix. We demonstrate that analytical power agrees well with simulated power for as few as eight clusters, when data are analyzed using bias-corrected estimating equations for the correlation parameters concurrently with a bias-corrected sandwich variance estimator. © 2018, The International Biometric Society.

  2. Comparison of a Stratified Group Intervention (STarT Back) With Usual Group Care in Patients With Low Back Pain: A Nonrandomized Controlled Trial.

    PubMed

    Murphy, Susan E; Blake, Catherine; Power, Camillus K; Fullen, Brona M

    2016-04-01

    A nonrandomized controlled trial. This study aims to explore the effectiveness of group-based stratified care in primary care. Stratified care based on psychosocial screening (STarT Back) has demonstrated greater clinical and cost-effectiveness in patients with low back pain. However, low back pain interventions are often delivered in groups and evaluating this system of care in a group setting is important. Patients were recruited from 60 general practices and linked physiotherapy services. A new group stratified intervention was compared with a historical nonstratified control group. Patients stratified as low, medium and high risk were offered risk-matched group care. Consenting participants completed self-report measures of functional disability (primary outcome measure), pain, psychological distress, and beliefs. The historical control received a generic group intervention. Analysis was by intention to treat. In total, 251 patients in the new stratified intervention and 332 in the historical control were included in the primary analysis at 12 weeks. The mean age of patients was 43 ± 10.98 years. Overall adjusted mean changes in the RMDQ scores were higher in the stratified intervention than in the control arm at 12-week follow-up (P = 0.028). Exploring the risk groups, individually the high-risk stratified group, demonstrated better outcome over the controls (P = 0.031). The medium-risk stratified intervention demonstrated equally good outcomes (P = 0.125), and low-risk stratified patients, despite less intervention, did as well as the historical controls (P = 0.993). Stratified care delivered in a group setting demonstrated superior outcomes in the high-risk patients, and equally good outcomes for the medium and low-risk groups. This model, embedded in primary care, provides an early and effective model of chronic disease management and adds another dimension to the utility of the STarT Back system of care. 2.

  3. Age-relationships of Toxocara canis seropositivity and geohelminth infection prevalence in two communities in St. Lucia, West Indies.

    PubMed

    Bundy, D A; Thompson, D E; Robertson, B D; Cooper, E S

    1987-12-01

    Sera were examined from an age-stratified sample of two Caribbean communities using the Toxocara-ELISA with larval ES antigen. Seropositivity was markedly age dependent, attaining maximal values (40 and 60%) in 5-15 year olds and declining in adults. The rate of acquisition of infection with Toxocara canis and the age-prevalence profile are similar to those of Ascaris lumbricoides and Trichuris trichiura. It is suggested that toxocariasis is likely to be prevalent in tropical areas with endemic geohelminthiasis.

  4. Free Falling in Stratified Fluids

    NASA Astrophysics Data System (ADS)

    Lam, Try; Vincent, Lionel; Kanso, Eva

    2017-11-01

    Leaves falling in air and discs falling in water are examples of unsteady descents due to complex interaction between gravitational and aerodynamic forces. Understanding these descent modes is relevant to many branches of engineering and science such as estimating the behavior of re-entry space vehicles to studying biomechanics of seed dispersion. For regularly shaped objects falling in homogenous fluids, the motion is relatively well understood. However, less is known about how density stratification of the fluid medium affects the falling behavior. Here, we experimentally investigate the descent of discs in both pure water and in stable linearly stratified fluids for Froude numbers Fr 1 and Reynolds numbers Re between 1000 -2000. We found that stable stratification (1) enhances the radial dispersion of the disc at landing, (2) increases the descent time, (3) decreases the inclination (or nutation) angle, and (4) decreases the fluttering amplitude while falling. We conclude by commenting on how the corresponding information can be used as a predictive model for objects free falling in stratified fluids.

  5. Consumer preference and effect of correct or misleading information after ageing beef longissimus muscle using vacuum, dry ageing, or a dry ageing bag.

    PubMed

    Stenström, Helena; Li, Xin; Hunt, Melvin C; Lundström, Kerstin

    2014-02-01

    The objective of this study was to determine which ageing treatment of beef was sensorially preferred by consumers and how their preference changed when given information about the ageing treatment used. Longissimus thoracis et lumborum from four young bulls were randomly assigned three ageing treatments: dry ageing, vacuum ageing and ageing in a highly moisture permeable bag (bag dry-ageing); each was aged at 1.6 °C for another 13 days. A preference test (171 consumers) with questions about overall liking, tenderness, and juiciness was performed. Thereafter, a deceptive test (61 consumers) was performed with two taste samples, the first taste sample with correct information about ageing treatment and the second with false information. In the preference test, consumers preferred dry ageing and bag dry-ageing to vacuum ageing. In the deceptive test, dry ageing was preferred, but the information given influenced preference. © 2013.

  6. Effects of sampling design on age ratios of migrants captured at stopover sites

    Treesearch

    Jeffrey F. Kelly; Deborah M. Finch

    2000-01-01

    Age classes of migrant songbirds often differ in migration timing. This difference creates the potential for age-ratios recorded at stopover sites to vary with the amount and distribution of sampling effort used. To test for these biases, we sub-sampled migrant capture data from the Middle Rio Grande Valley of New Mexico. We created data sets that reflected the age...

  7. The timing of alcohol use and sexual initiation among a sample of Black, Hispanic, and White adolescents.

    PubMed

    Rothman, Emily F; Wise, Lauren A; Bernstein, Edward; Bernstein, Judith

    2009-01-01

    The goals of this study were to examine the relationship between age at first drink and age at first sex among an emergency department sample of Black, Hispanic, and White adolescents (N = 1,1110) and to assess two sexual behavior-related consequences of underage drinking. The authors used multivariable linear regression to analyze data from a self-reported survey. Age at first sex decreased linearly with decreasing age at first drink (p < .001) for all adolescents in the sample. In analyses stratified by race, significant positive trends between age at first drink and age at first sex were observed for all race and ethnic subgroups, although the relationship between age at first drink and age at first sex was not as strong for Black males and females as their White counterparts, respectively. Compared to White males, Black males were less likely to report having had sex without using a condom or birth control after drinking in the past month and during their lifetimes.

  8. The 40-Something randomized controlled trial to prevent weight gain in mid-age women

    PubMed Central

    2013-01-01

    Background Obesity prevention is a major public health priority. Despite the health risks associated with weight gain, there has been a distinct lack of research into effective interventions to prevent, rather than treat, obesity particularly at high risk life stages such as menopause in women. This paper describes the rationale for and design of a 2-year randomized controlled trial (RCT) (the 40-Something Study) aimed at testing the feasibility and efficacy of a relatively low intensity intervention designed to achieve weight control in non-obese women about to enter the menopause transition. Methods and design The study is a parallel-group RCT consisting of 12 months of intervention (Phase 1) and 12 months of monitoring (Phase 2). Non-obese pre-menopausal healthy females 44–50 years of age were screened, stratified according to Body Mass Index (BMI) category (18.5-24.9 and 25–29.9 kg/m2) and randomly assigned to one of two groups: motivational interviewing (MI) intervention (n = 28), or a self-directed intervention (SDI) (control) (n = 26). The MI intervention consisted of five consultations with health professionals (four with a Dietitian and one with an Exercise Physiologist) who applied components of MI counselling to consultations with the women over a 12 month period. The SDI was developed as a control and these participants received print materials only. Outcome measures were collected at baseline, three, 12, 18 and 24 months and included weight (primary outcome), waist circumference, body composition, blood pressure, plasma markers of metabolic syndrome risk, dietary intake, physical activity and quality of life. Analysis of covariance will be used to investigate outcomes according to intervention type and duration (comparing baseline, 12 and 24 months). Discussion The 40-Something study is the first RCT aimed at preventing menopausal weight gain in Australian women. Importantly, this paper describes the methods used to evaluate whether

  9. Thermal Vibrational Convection in a Two-phase Stratified Liquid

    NASA Technical Reports Server (NTRS)

    Chang, Qingming; Alexander, J. Iwan D.

    2007-01-01

    The response of a two-phase stratified liquid system subject to a vibration parallel to an imposed temperature gradient is analyzed using a hybrid thermal lattice Boltzmann method (HTLB). The vibrations considered correspond to sinusoidal translations of a rigid cavity at a fixed frequency. The layers are thermally and mechanically coupled. Interaction between gravity-induced and vibration-induced thermal convection is studied. The ability of applied vibration to enhance the flow, heat transfer and interface distortion is investigated. For the range of conditions investigated, the results reveal that the effect of vibrational Rayleigh number and vibrational frequency on a two-phase stratified fluid system is much different than that for a single-phase fluid system. Comparisons of the response of a two-phase stratified fluid system with a single-phase fluid system are discussed.

  10. Ventilatory Function in Relation to Mining Experience and Smoking in a Random Sample of Miners and Non-miners in a Witwatersrand Town1

    PubMed Central

    Sluis-Cremer, G. K.; Walters, L. G.; Sichel, H. S.

    1967-01-01

    The ventilatory capacity of a random sample of men over the age of 35 years in the town of Carletonville was estimated by the forced expiratory volume and the peak expiratory flow rate. Five hundred and sixty-two persons were working or had worked in gold-mines and 265 had never worked in gold-mines. No difference in ventilatory function was found between the miners and non-miners other than that due to the excess of chronic bronchitis in miners. PMID:6017134

  11. Post-stratified estimation: with-in strata and total sample size recommendations

    Treesearch

    James A. Westfall; Paul L. Patterson; John W. Coulston

    2011-01-01

    Post-stratification is used to reduce the variance of estimates of the mean. Because the stratification is not fixed in advance, within-strata sample sizes can be quite small. The survey statistics literature provides some guidance on minimum within-strata sample sizes; however, the recommendations and justifications are inconsistent and apply broadly for many...

  12. An interpretation of the spectral properties of hot hydrogen-rich white dwarfs with stratified H/He model atmospheres

    NASA Technical Reports Server (NTRS)

    Vennes, Stephane; Fontaine, Gilles

    1992-01-01

    A grid of stratified H/He model atmospheres applicable to the interpretation of the spectral properties of hot H-rich white dwarfs (WDs) is computed. Samples of hot DA WDs observed with Exosat and Einstein are analyzed using the models. Six out of six objects with T(eff) = 35,000 K or less do not show a EUV/soft X-ray flux deficiency and therefore can be understood solely in terms of pure hydrogen atmospheres. A majority of DA WDs hotter than this value do show a flux deficiency and thus require the presence of some absorbers in their atmospheres. It is shown that the Exosat broadband photometry of Feige 24 and G191 B2B cannot be explained in terms of stratified atmospheres. Absorption by heavy elements is certainly responsible for the required EUV/soft X-ray opacity source in these cases. However, the Exosat data are consistent with the hypothesis of stratified atmospheres in the four remaining objects.

  13. Cross-sectional study of height and weight in the population of Andalusia from age 3 to adulthood

    PubMed Central

    López-Siguero, Juan Pedro; García, Juan Manuel Fernández; Castillo, Juan de Dios Luna; Molina, Jose Antonio Moreno; Cosano, Carlos Ruiz; Ortiz, Antonio Jurado

    2008-01-01

    Background and objectives In Andalusia there were no studies including a representative sample of children and adolescent population assessing growth and weight increase. Our objectives were to develop reference standards for weight, height and BMI for the Andalusian pediatric population, from 3 to 18 years of age for both genders, and to identify the final adult height in Andalusia. Subjects and methods Two samples were collected. The first included individuals from 3 to 18 years of age (3592 girls and 3605 boys). They were stratified according type of study center, size of population of origin, age (32 categories of 0.5 years) and gender, using cluster sampling. Subjects from >18 to 23 years of age (947 women and 921 men) were sampled in 6 non-university educational centers and several university centers in Granada. Exclusion criteria included sons of non-Spanish mother or father, and individuals with chronic conditions and/or therapies affecting growth. Two trained fellows collected the data through February to December 2004, for the first sample, and through January to May 2005, for the second. Reference curves were adjusted using Cole's LMS method, and the quality of the adjustment was assessed using the tests proposed by Royston. In addition, a sensitivity analysis was applied to the final models obtained. Results Data for 9065 cases (4539 women and 4526 men) were obtained; 79.39% (n = 7197) in the up to 18 years of age group. In the first sampling only 0.07% (3 girls and 2 boys) refused to participate in the study. In addition, 327 students (4.5%) were absent when sampling was done. We present mean and standard deviation fort height, weight and BMI at 0.5 years intervals, from 3 to 23 years of age, for both genders. After adjustment with the different models, percentiles for height, weight (percentiles 3, 5, 10, 25, 50, 75, 90, 95, and 97) and BMI (percentiles 3, 5, 50, 85, 95, and 97) are presented for both genders. Conclusion This is the first study in

  14. Gear comparison for sampling age-0 Mountain Whitefish in the Madison River, Montana

    USGS Publications Warehouse

    Boyer, Jan K.; Guy, Christopher S.; Webb, Molly A.H.; Horton, Travis B.; McMahon, Thomas E.

    2017-01-01

    The efficacy of various sampling gears for age-0 Mountain Whitefish Prosopium williamsoni is largely unknown, which makes it difficult to investigate recruitment and early life history dynamics for the species. We compared four gears: seine, backpack electrofisher, minnow trap, and lighted minnow trap. Gears were tested in backwaters, large channels, and small channels in the Madison River, Montana. No age-0 Mountain Whitefish were captured in minnow traps or lighted minnow traps. Mean CPUE of age-0 Mountain Whitefish was higher for seining (0.18 fish/m2; SD, 0.39) than for electrofishing (0.01 fish/m2; SD, 0.03), and the CV was lower for seining. A broader length distribution was sampled by seining (17–41 mm) than with electrofishing (21–36 mm). Age-0 Mountain Whitefish CPUE in seines was highest in backwaters. In channel sites, Mountain Whitefish presence was associated with areas of still or slow water ≥2 m2. Relative to the other sampling gears we evaluated, seining was the most efficient gear for sampling age-0 Mountain Whitefish in a lotic ecosystem.

  15. Transport and Lagrangian Statistics in Rotating Stratified Turbulence

    NASA Astrophysics Data System (ADS)

    Rosenberg, D. L.

    2015-12-01

    Transport plays a crucial role in geophysical flows, both in theatmosphere and in the ocean. Transport in such flows is ultimatelycontrolled by small-scale turbulence, although the large scales arein geostrophic balance between pressure gradient, gravity and Coriolisforces. As a result of the seemingly random nature of the flow, singleparticles are dispersed by the flow and on time scales significantlylonger than the eddy turn-over time, they undergo a diffusive motionwhose diffusion coefficient is the integral of the velocity correlationfunction. On intermediate time scales, in homogeneous, isotropic turbuilence(HIT) the separation between particle pairs has been argued to grow withtime according to the Richardson law: <(Δ x)2(t)> ~ t3, with aproportionality constant that depends on the initial particleseparation. The description of the phenomena associated withthe dispersion of single particles, or of particle pairs, ultimatelyrests on relatively simple statistical properties of the flowvelocity transporting the particles, in particular on its temporalcorrelation function. In this work, we investigate particle dispersionin the anisotropic case of rotating stratified turbulence examining whetherthe dependence on initial particle separation differs from HIT,particularly in the presence of an inverse cascade.

  16. Evaluation of immunization coverage by lot quality assurance sampling compared with 30-cluster sampling in a primary health centre in India.

    PubMed

    Singh, J; Jain, D C; Sharma, R S; Verghese, T

    1996-01-01

    The immunization coverage of infants, children and women residing in a primary health centre (PHC) area in Rajasthan was evaluated both by lot quality assurance sampling (LQAS) and by the 30-cluster sampling method recommended by WHO's Expanded Programme on Immunization (EPI). The LQAS survey was used to classify 27 mutually exclusive subunits of the population, defined as residents in health subcentre areas, on the basis of acceptable or unacceptable levels of immunization coverage among infants and their mothers. The LQAS results from the 27 subcentres were also combined to obtain an overall estimate of coverage for the entire population of the primary health centre, and these results were compared with the EPI cluster survey results. The LQAS survey did not identify any subcentre with a level of immunization among infants high enough to be classified as acceptable; only three subcentres were classified as having acceptable levels of tetanus toxoid (TT) coverage among women. The estimated overall coverage in the PHC population from the combined LQAS results showed that a quarter of the infants were immunized appropriately for their ages and that 46% of their mothers had been adequately immunized with TT. Although the age groups and the periods of time during which the children were immunized differed for the LQAS and EPI survey populations, the characteristics of the mothers were largely similar. About 57% (95% CI, 46-67) of them were found to be fully immunized with TT by 30-cluster sampling, compared with 46% (95% CI, 41-51) by stratified random sampling. The difference was not statistically significant. The field work to collect LQAS data took about three times longer, and cost 60% more than the EPI survey. The apparently homogeneous and low level of immunization coverage in the 27 subcentres makes this an impractical situation in which to apply LQAS, and the results obtained were therefore not particularly useful. However, if LQAS had been applied by local

  17. Geohydrology and water quality of stratified-drift aquifers in the Saco and Ossipee River basins, east-central New Hampshire

    USGS Publications Warehouse

    Moore, R.B.; Medalie, Laura

    1995-01-01

    Stratified-drift aquifers discontinuously underlie 152.5 square miles of the Saco and Ossipee River Basins, which have a total drainage area of 869.4 square miles. Saturated thicknesses of stratified drift in the study area are locally greater than 280 feet, but generally are less. Transmissivity locally exceeds 8,000 feet squared per day but are generally less. About 93.6 square miles, or 10.8 percent of the study area, are identified as having transmissivity greater than 1,000 feet squared per day. The stratified-drift aquifer in Ossipee, Freedom, Effingham, Madison, and Tamworth was analyzed for the availability of ground water by use of transient simulations and a two-dimensional, finite-difference ground-water-flow model. The numerical -model results indicate that potential available water amounts in this aquifer are 7.72 million gallons per day. Sample results of water- quality analyses obtained from 25 test wells and 4 springs indicated that water was generally suitable for drinking and other domestic purposes. Concen- trations of dissolved constituents in ground-water samples are less than or meet U.S. Environmental Protection Agency (USEPA)primary and secondary drinking-water regulations. Concentrations of inorganic constituents that exceeded the USEPA's secondary regulations were chloride and sodium, iron manganese, and fluoride.

  18. Demythologizing sex education in Oklahoma: an attitudinal study.

    PubMed

    Turner, N H

    1983-08-01

    A randomized study was conducted to determine the distribution of attitudes among Oklahomans of voting age toward sex education and to analyze the relationship of demographic, sociocultural, and attitudinal factors. The state was stratified into six regions. Forty-five percent of the sample lived in urban areas, and 55% in rural areas. Random digit dialing and random selection within households were utilized to ensure a representative sample of the population. Eighty percent of the sample was found to be favorable toward sex education in the public schools, while 20% was unfavorable. A majority of respondents in all religious groups including "fundamentalists" were favorable. Seventeen variables were found to be significant in the univariate analysis of the data; eight were not significant. In a multivariate analysis, three variables, age, Protestant denominational type and female employment, were shown to have predictive ability in determining favorability and unfavorability. Implications for building community support for sex education also are discussed.

  19. Projecting Age-Stratified Risk of Exposure to Inland Flooding and Wildfire Smoke in the United States under Two Climate Scenarios.

    PubMed

    Mills, David; Jones, Russell; Wobus, Cameron; Ekstrom, Julia; Jantarasami, Lesley; St Juliana, Alexis; Crimmins, Allison

    2018-04-17

    The public health community readily recognizes flooding and wildfires as climate-related health hazards, but few studies quantify changes in risk of exposure, particularly for vulnerable children and older adults. This study quantifies future populations potentially exposed to inland flooding and wildfire smoke under two climate scenarios, highlighting the populations in particularly vulnerable age groups (≤4 y old and ≥65 y old). Spatially explicit projections of inland flooding and wildfire under two representative concentration pathways (RCP8.5 and RCP4.5) are integrated with static (2010) and dynamic (2050 and 2090) age-stratified projections of future contiguous U.S. populations at the county level. In both 2050 and 2090, an additional one-third of the population will live in areas affected by larger and more frequent inland flooding under RCP8.5 than under RCP4.5. Approximately 15 million children and 25 million older adults could avoid this increased risk of flood exposure each year by 2090 under a moderate mitigation scenario (RCP4.5 compared with RCP8.5). We also find reduced exposure to wildfire smoke under the moderate mitigation scenario. Nearly 1 million young children and 1.7 million older adults would avoid exposure to wildfire smoke each year under RCP4.5 than under RCP8.5 by the end of the century. By integrating climate-driven hazard and population projections, newly created county-level exposure maps identify locations of potential significant future public health risk. These potential exposure results can help inform actions to prevent and prepare for associated future adverse health outcomes, particularly for vulnerable children and older adults. https://doi.org/10.1289/EHP2594.

  20. Complementary nonparametric analysis of covariance for logistic regression in a randomized clinical trial setting.

    PubMed

    Tangen, C M; Koch, G G

    1999-03-01

    In the randomized clinical trial setting, controlling for covariates is expected to produce variance reduction for the treatment parameter estimate and to adjust for random imbalances of covariates between the treatment groups. However, for the logistic regression model, variance reduction is not obviously obtained. This can lead to concerns about the assumptions of the logistic model. We introduce a complementary nonparametric method for covariate adjustment. It provides results that are usually compatible with expectations for analysis of covariance. The only assumptions required are based on randomization and sampling arguments. The resulting treatment parameter is a (unconditional) population average log-odds ratio that has been adjusted for random imbalance of covariates. Data from a randomized clinical trial are used to compare results from the traditional maximum likelihood logistic method with those from the nonparametric logistic method. We examine treatment parameter estimates, corresponding standard errors, and significance levels in models with and without covariate adjustment. In addition, we discuss differences between unconditional population average treatment parameters and conditional subpopulation average treatment parameters. Additional features of the nonparametric method, including stratified (multicenter) and multivariate (multivisit) analyses, are illustrated. Extensions of this methodology to the proportional odds model are also made.

  1. Stratified turbulence diagnostics for high-Reynolds-number momentum wakes

    NASA Astrophysics Data System (ADS)

    Diamessis, Peter; Zhou, Qi

    2017-11-01

    We analyze a large-eddy simulation (LES) dataset of the turbulent wake behind a sphere of diameter D translating at speed U in a linearly stratified Boussinesq fluid with buoyancy frequency N. These simulations are performed at Reynolds numbers Re ≡ UD / ν ∈ { 5 ×103 , 105 , 4 ×105 } and various Froude numbers Fr ≡ 2 U /(ND) . The recently obtained data at Re = 4 ×105 , the highest Re attained so far in either simulation or laboratory, and Fr ∈ { 4 , 16 } enable us to systematically investigate the effects of Reynolds number on this prototypical localized stratified turbulent shear flow. Our analysis focuses on the time evolution of various diagnostics of stratified turbulence, such as the horizontal and vertical integral length scales, turbulent kinetic energy and its dissipation rate ɛ, and the local rate of shear between the spontaneously formed layers of vorticity within the larger-scale quasi-horizontal flow structures. This leads to a discussion of the transitions between distinct stratified flow regimes (Brethouwer et al. 2007) in the appropriately defined phase diagram, and we highlight the dynamical role of the Gibson number Gi = ɛ /(νN2) , and its dependence on the body-based Reynolds number Re . ONR Grants N00014-13-1-0665 and N00014-15-1-2513.

  2. Formation of temperature front in stably stratified turbulence

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshifumi; Sullivan, Peter; Herring, Jackson

    2016-11-01

    An important feature of stably stratified turbulence is the significant influence of internal gravity waves which makes stably stratified turbulence unique compared to homogeneous isotropic turbulence. In this paper, we investigate the genesis of temperature fronts-a crucial subject both practically and fundamentally-in stably stratified turbulence using Direct Numerical Simulations (DNS) of the Navier-Stokes equation under the Boussinesq approximation with 10243 grid points. Vertical profiles of temperature fluctuations show almost vertically periodic sawtooth wavy structures with negative and positive layers stacked together with clear boundaries implying a sharp temperature fronts. The sawtooth waves consist of gradual decreasing temperature fluctuations with rapid recovery to a positive value as the frontal boundary is crossed vertically. This asymmetry of gradients comes from the structure that warm temperature region lies on top of cool temperature region, and can be verified in the skewed probability density function (PDF) of vertical temperature gradient. We try to extract the flow structures and mechanism for the formation and maintenance of the strong temperature front numerically.

  3. Stratified prevention: opportunities and limitations. Report on the 1st interdisciplinary cardiovascular workshop in Augsburg.

    PubMed

    Kirchhof, Gregor; Lindner, Josef Franz; Achenbach, Stephan; Berger, Klaus; Blankenberg, Stefan; Fangerau, Heiner; Gimpel, Henner; Gassner, Ulrich M; Kersten, Jens; Magnus, Dorothea; Rebscher, Herbert; Schunkert, Heribert; Rixen, Stephan; Kirchhof, Paulus

    2018-03-01

    Sufficient exercise and sleep, a balanced diet, moderate alcohol consumption and a good approach to handle stress have been known as lifestyles that protect health and longevity since the Middle Age. This traditional prevention quintet, turned into a sextet by smoking cessation, has been the basis of the "preventive personality" that formed in the twentieth century. Recent analyses of big data sets including genomic and physiological measurements have unleashed novel opportunities to estimate individual health risks with unprecedented accuracy, allowing to target preventive interventions to persons at high risk and at the same time to spare those in whom preventive measures may not be needed or even be harmful. To fully grasp these opportunities for modern preventive medicine, the established healthy life styles require supplementation by stratified prevention. The opportunities of these developments for life and health contrast with justified concerns: A "surveillance society", able to predict individual behaviour based on big data, threatens individual freedom and jeopardises equality. Social insurance law and the new German Disease Prevention Act (Präventionsgesetz) rightly stress the need for research to underpin stratified prevention which is accessible to all, ethical, effective, and evidence based. An ethical and acceptable development of stratified prevention needs to start with autonomous individuals who control and understand all information pertaining to their health. This creates a mandate for lifelong health education, enabled in an individualised form by digital technology. Stratified prevention furthermore requires the evidence-based development of a new taxonomy of cardiovascular diseases that reflects disease mechanisms. Such interdisciplinary research needs broad support from society and a better use of biosamples and data sets within an updated research governance framework.

  4. Reducing suicidal ideation and depressive symptoms in depressed older primary care patients: a randomized controlled trial.

    PubMed

    Bruce, Martha L; Ten Have, Thomas R; Reynolds, Charles F; Katz, Ira I; Schulberg, Herbert C; Mulsant, Benoit H; Brown, Gregory K; McAvay, Gail J; Pearson, Jane L; Alexopoulos, George S

    2004-03-03

    Suicide rates are highest in late life; the majority of older adults who die by suicide have seen a primary care physician in preceding months. Depression is the strongest risk factor for late-life suicide and for suicide's precursor, suicidal ideation. To determine the effect of a primary care intervention on suicidal ideation and depression in older patients. Randomized controlled trial known as PROSPECT (Prevention of Suicide in Primary Care Elderly: Collaborative Trial) with patient recruitment from 20 primary care practices in New York City, Philadelphia, and Pittsburgh regions, May 1999 through August 2001. Two-stage, age-stratified (60-74, > or =75 years) depression screening of randomly sampled patients; enrollment included patients who screened positive and a random sample of screened negative patients. This analysis included patients with a depression diagnosis (N = 598). Treatment guidelines tailored for the elderly with care management compared with usual care. Assessment of suicidal ideation and depression severity at baseline, 4 months, 8 months, and 12 months. Rates of suicidal ideation declined faster (P =.01) in intervention patients compared with usual care patients; at 4 months, in the intervention group, raw rates of suicidal ideation declined 12.9% points (29.4% to 16.5%) compared with 3.0% points (20.1% to 17.1% in usual care [P =.01]). Among patients reporting suicidal ideation, resolution of ideation was faster among intervention patients (P =.03); differences peaked at 8 months (70.7% vs 43.9% resolution; P =.005). Intervention patients had a more favorable course of depression in both degree and speed of symptom reduction; group difference peaked at 4 months. The effects on depression were not significant among patients with minor depression unless suicidal ideation was present. Evidence of the intervention's effectiveness in community-based primary care with a heterogeneous sample of depressed patients introduces new challenges related to

  5. Quantifying Uncertainties from Presence Data Sampling Methods for Species Distribution Modeling: Focused on Vegetation.

    NASA Astrophysics Data System (ADS)

    Sung, S.; Kim, H. G.; Lee, D. K.; Park, J. H.; Mo, Y.; Kil, S.; Park, C.

    2016-12-01

    The impact of climate change has been observed throughout the globe. The ecosystem experiences rapid changes such as vegetation shift, species extinction. In these context, Species Distribution Model (SDM) is one of the popular method to project impact of climate change on the ecosystem. SDM basically based on the niche of certain species with means to run SDM present point data is essential to find biological niche of species. To run SDM for plants, there are certain considerations on the characteristics of vegetation. Normally, to make vegetation data in large area, remote sensing techniques are used. In other words, the exact point of presence data has high uncertainties as we select presence data set from polygons and raster dataset. Thus, sampling methods for modeling vegetation presence data should be carefully selected. In this study, we used three different sampling methods for selection of presence data of vegetation: Random sampling, Stratified sampling and Site index based sampling. We used one of the R package BIOMOD2 to access uncertainty from modeling. At the same time, we included BioCLIM variables and other environmental variables as input data. As a result of this study, despite of differences among the 10 SDMs, the sampling methods showed differences in ROC values, random sampling methods showed the lowest ROC value while site index based sampling methods showed the highest ROC value. As a result of this study the uncertainties from presence data sampling methods and SDM can be quantified.

  6. Personality, self-rated health, and subjective age in a life-span sample: the moderating role of chronological age.

    PubMed

    Stephan, Yannick; Demulier, Virginie; Terracciano, Antonio

    2012-12-01

    The present study tested whether chronological age moderates the association between subjective age and self-rated health and personality in a community-dwelling life-span sample (N = 1,016; age range: 18-91 years). Self-rated health, extraversion, and openness to experience were associated with a younger subjective age at older ages. Conscientious individuals felt more mature early in life. Conscientiousness, neuroticism, and agreeableness were not related to subjective age at older ages. These findings suggest that with aging self-rated health and personality traits are increasingly important for subjective age. 2013 APA, all rights reserved

  7. PLUME DISPERSION IN STABLY STRATIFIED FLOWS OVER COMPLEX TERRAIN, PHASE 2

    EPA Science Inventory

    Laboratory experiments were conducted in a stratified towing tank to investigate plume dispersion in stably stratified flows. First, plume dispersion over an idealized terrain model with a simulated elevated inversion in the atmosphere was investigated. These results were compare...

  8. Effectiveness of water fluoridation in the prevention of dental caries across adult age groups.

    PubMed

    Do, Loc; Ha, Diep; Peres, Marco A; Skinner, John; Byun, Roy; Spencer, A John

    2017-06-01

    Lifetime access to fluoridated water (FW) is associated with lower caries experience. However, assessing this association in adults is likely affected by age. Cohort stratification and categorization of per cent lifetime access to fluoridated water (% LAFW) within cohorts are current approaches to this assessment. These approaches require an examination of the % LAFW and caries experience variation within and across age groups and their association to inform future analyses. This secondary analysis aimed to examine the age group variation in % LAFW and caries experience; and the association of % LAFW with caries within and across age groups of adults. A secondary analysis was undertaken using the Australian National Survey of Adult Oral Health 2004-2006 data on 4090 persons aged 15-91 years randomly sampled by a stratified, multistage probability method. Study participants underwent an interview, an oral examination by trained and standardized dentists to determine decayed, missing or filled tooth surfaces (DMFS) and a mailed self-complete questionnaire which collected residential history to calculate % LAFW. Variations in % LAFW and DMFS across age groups (15-34; 35-44; 45-54; 55+) were examined. Multivariable regression log-link models were generated for DMFS score within each age group. The age groups varied in values and distribution of % LAFW. Caries experience was strongly associated with age. % LAFW was significantly associated with DMFS score in the two younger age groups, but not in the others. Multivariable regression models showed that the highest % LAFW quartile had significantly lower DMFS count than the lowest quartile in the two younger age groups (mean ratios: 0.67 and 0.78, respectively), controlling for other covariates. Access to FW was associated with caries experience in Australian adults. The magnitude of associations varied between age groups, dependent on the natural history of caries and its measurement by DMFS. © 2017 John Wiley & Sons A

  9. Event-triggered synchronization for reaction-diffusion complex networks via random sampling

    NASA Astrophysics Data System (ADS)

    Dong, Tao; Wang, Aijuan; Zhu, Huiyun; Liao, Xiaofeng

    2018-04-01

    In this paper, the synchronization problem of the reaction-diffusion complex networks (RDCNs) with Dirichlet boundary conditions is considered, where the data is sampled randomly. An event-triggered controller based on the sampled data is proposed, which can reduce the number of controller and the communication load. Under this strategy, the synchronization problem of the diffusion complex network is equivalently converted to the stability of a of reaction-diffusion complex dynamical systems with time delay. By using the matrix inequality technique and Lyapunov method, the synchronization conditions of the RDCNs are derived, which are dependent on the diffusion term. Moreover, it is found the proposed control strategy can get rid of the Zeno behavior naturally. Finally, a numerical example is given to verify the obtained results.

  10. Age- and sex-specific causal effects of adiposity on cardiovascular risk factors.

    PubMed

    Fall, Tove; Hägg, Sara; Ploner, Alexander; Mägi, Reedik; Fischer, Krista; Draisma, Harmen H M; Sarin, Antti-Pekka; Benyamin, Beben; Ladenvall, Claes; Åkerlund, Mikael; Kals, Mart; Esko, Tõnu; Nelson, Christopher P; Kaakinen, Marika; Huikari, Ville; Mangino, Massimo; Meirhaeghe, Aline; Kristiansson, Kati; Nuotio, Marja-Liisa; Kobl, Michael; Grallert, Harald; Dehghan, Abbas; Kuningas, Maris; de Vries, Paul S; de Bruijn, Renée F A G; Willems, Sara M; Heikkilä, Kauko; Silventoinen, Karri; Pietiläinen, Kirsi H; Legry, Vanessa; Giedraitis, Vilmantas; Goumidi, Louisa; Syvänen, Ann-Christine; Strauch, Konstantin; Koenig, Wolfgang; Lichtner, Peter; Herder, Christian; Palotie, Aarno; Menni, Cristina; Uitterlinden, André G; Kuulasmaa, Kari; Havulinna, Aki S; Moreno, Luis A; Gonzalez-Gross, Marcela; Evans, Alun; Tregouet, David-Alexandre; Yarnell, John W G; Virtamo, Jarmo; Ferrières, Jean; Veronesi, Giovanni; Perola, Markus; Arveiler, Dominique; Brambilla, Paolo; Lind, Lars; Kaprio, Jaakko; Hofman, Albert; Stricker, Bruno H; van Duijn, Cornelia M; Ikram, M Arfan; Franco, Oscar H; Cottel, Dominique; Dallongeville, Jean; Hall, Alistair S; Jula, Antti; Tobin, Martin D; Penninx, Brenda W; Peters, Annette; Gieger, Christian; Samani, Nilesh J; Montgomery, Grant W; Whitfield, John B; Martin, Nicholas G; Groop, Leif; Spector, Tim D; Magnusson, Patrik K; Amouyel, Philippe; Boomsma, Dorret I; Nilsson, Peter M; Järvelin, Marjo-Riitta; Lyssenko, Valeriya; Metspalu, Andres; Strachan, David P; Salomaa, Veikko; Ripatti, Samuli; Pedersen, Nancy L; Prokopenko, Inga; McCarthy, Mark I; Ingelsson, Erik

    2015-05-01

    Observational studies have reported different effects of adiposity on cardiovascular risk factors across age and sex. Since cardiovascular risk factors are enriched in obese individuals, it has not been easy to dissect the effects of adiposity from those of other risk factors. We used a Mendelian randomization approach, applying a set of 32 genetic markers to estimate the causal effect of adiposity on blood pressure, glycemic indices, circulating lipid levels, and markers of inflammation and liver disease in up to 67,553 individuals. All analyses were stratified by age (cutoff 55 years of age) and sex. The genetic score was associated with BMI in both nonstratified analysis (P = 2.8 × 10(-107)) and stratified analyses (all P < 3.3 × 10(-30)). We found evidence of a causal effect of adiposity on blood pressure, fasting levels of insulin, C-reactive protein, interleukin-6, HDL cholesterol, and triglycerides in a nonstratified analysis and in the <55-year stratum. Further, we found evidence of a smaller causal effect on total cholesterol (P for difference = 0.015) in the ≥55-year stratum than in the <55-year stratum, a finding that could be explained by biology, survival bias, or differential medication. In conclusion, this study extends previous knowledge of the effects of adiposity by providing sex- and age-specific causal estimates on cardiovascular risk factors. © 2015 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.

  11. Comparison of sampling designs for estimating deforestation from landsat TM and MODIS imagery: a case study in Mato Grosso, Brazil.

    PubMed

    Zhu, Shanyou; Zhang, Hailong; Liu, Ronggao; Cao, Yun; Zhang, Guixin

    2014-01-01

    Sampling designs are commonly used to estimate deforestation over large areas, but comparisons between different sampling strategies are required. Using PRODES deforestation data as a reference, deforestation in the state of Mato Grosso in Brazil from 2005 to 2006 is evaluated using Landsat imagery and a nearly synchronous MODIS dataset. The MODIS-derived deforestation is used to assist in sampling and extrapolation. Three sampling designs are compared according to the estimated deforestation of the entire study area based on simple extrapolation and linear regression models. The results show that stratified sampling for strata construction and sample allocation using the MODIS-derived deforestation hotspots provided more precise estimations than simple random and systematic sampling. Moreover, the relationship between the MODIS-derived and TM-derived deforestation provides a precise estimate of the total deforestation area as well as the distribution of deforestation in each block.

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

    NASA Astrophysics Data System (ADS)

    Lv, Chao; Zheng, Lianqing; Yang, Wei

    2012-01-01

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

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Romero, Vicente; Bonney, Matthew; Schroeder, Benjamin

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

  14. [The vitamin D nutritional status in Chinese urban women of child-bearing age from 2010 to 2012].

    PubMed

    Lu, J X; Liu, X B; Chen, J; Hu, Y C; Yun, C F; Li, W D; Wang, R; Yang, Y H; Mao, D Q; Piao, J H; Yang, X G; Yang, L C

    2017-02-06

    Objective: To evaluate the vitamin D nutritional status in Chinese women of child-bearing age by analyzing serum 25-hydroxyvitamin D level in 2010-2012. Methods: Data were obtained from the China Nutrition and Health Survey in 2010-2012. Using cluster sampling and proportional stratified random sampling, 1 514 women of child-bearing age (18-44 years old) from 34 metropolis and 41 small and medium-sized cities were included in this study. Demographic information was collected by questionnaire and serum 25-hydroxyvitamin D concentration was determined by radioimmunoassay, in accordance with the 2010 Institute of Medicine of the National Academies standards. We compared differences in vitamin D levels, specifically serious deficiency, lack of deficiency, insufficiency, and excess. Results: The overall serum 25-hydroxyvitamin D level of Chinese urban women of child-bearing age ( P (50) ( P (25)- P (75))) was 20.1 (15.1-26.3) ng/ml; minorities had a significantly higher serum 25-hydroxyvitamin D level of 22.0 (15.9-27.5) ng/ml compared with women of Han nationality (19.8 (14.9-26.2) ng/ml) (χ(2)=7.02, P= 0.008). The proportions of women with serious deficiency, lack of deficiency, insufficiency, and excess vitamin D were 11.6% ( n= 175), 37.9% ( n= 574), 35.1% ( n= 531), and 0.3% ( n= 5), respectively. Only 15.1% ( n= 229) of women of child-bearing age had normal vitamin D nutritional status. No significant differences in vitamin D nutritional status were observed according to age, body mass index, city, nationality, educational level, marital status, or household income per capita ( P> 0.05). Conclusion: Most Chinese urban women of child-bearing age have poor vitamin D levels and require vitamin D supplementation.

  15. SINDA/FLUINT Stratified Tank Modeling for Cryrogenic Propellant Tanks

    NASA Technical Reports Server (NTRS)

    Sakowski, Barbara

    2014-01-01

    A general purpose SINDA/FLUINT (S/F) stratified tank model was created to simulate self-pressurization and axial jet TVS; Stratified layers in the vapor and liquid are modeled using S/F lumps.; The stratified tank model was constructed to permit incorporating the following additional features:, Multiple or singular lumps in the liquid and vapor regions of the tank, Real gases (also mixtures) and compressible liquids, Venting, pressurizing, and draining, Condensation and evaporation/boiling, Wall heat transfer, Elliptical, cylindrical, and spherical tank geometries; Extensive user logic is used to allow detailed tailoring - Don't have to rebuilt everything from scratch!!; Most code input for a specific case is done through the Registers Data Block:, Lump volumes are determined through user input:; Geometric tank dimensions (height, width, etc); Liquid level could be input as either a volume percentage of fill level or actual liquid level height

  16. Unsteady Shear Disturbances Within a Two Dimensional Stratified Flow

    NASA Technical Reports Server (NTRS)

    Yokota, Jeffrey W.

    1992-01-01

    The origin and evolution of shear disturbances within a stratified, inviscid, incompressible flow are investigated numerically by a Clebsch/Weber decomposition based scheme. In contrast to homogeneous flows, within which vorticity can be redistributed but not generated, the presence of a density stratification can render an otherwise irrotational flow vortical. In this work, a kinematic decomposition of the unsteady Euler equations separates the unsteady velocity field into rotational and irrotational components. The subsequent evolution of these components is used to study the influence various velocity disturbances have on both stratified and homogeneous flows. In particular, the flow within a two-dimensional channel is used to investigate the evolution of rotational disturbances, generated or convected, downstream from an unsteady inflow condition. Contrasting simulations of both stratified and homogeneous flows are used to distinguish between redistributed inflow vorticity and that which is generated by a density stratification.

  17. Landsat image and sample design for water reservoirs (Rapel dam Central Chile).

    PubMed

    Lavanderos, L; Pozo, M E; Pattillo, C; Miranda, H

    1990-01-01

    Spatial heterogeneity of the Rapel reservoir surface waters is analyzed through Landsat images. The image digital counts are used with the aim or developing an aprioristic quantitative sample design.Natural horizontal stratification of the Rapel Reservoir (Central Chile) is produced mainly by suspended solids. The spatial heterogeneity conditions of the reservoir for the Spring 86-Summer 87 period were determined by qualitative analysis and image processing of the MSS Landsat, bands 1 and 3. The space-time variations of the different observed strata obtained with multitemporal image analysis.A random stratified sample design (r.s.s.d) was developed, based on the digital counts statistical analysis. Strata population size as well as the average, variance and sampling size of the digital counts were obtained by the r.s.s.d method.Stratification determined by analysis of satellite images were later correlated with ground data. Though the stratification of the reservoir is constant over time, the shape and size of the strata varys.

  18. Influences of sex, age and education on attitudes towards gender inequitable norms and practices in South Sudan.

    PubMed

    Scott, Jennifer; Hacker, Michele; Averbach, Sarah; Modest, Anna M; Cornish, Sarah; Spencer, Danielle; Murphy, Maureen; Parmar, Parveen

    2014-01-01

    Prolonged conflict in South Sudan exacerbated gender disparities and inequities. This study assessed differences in attitudes towards gender inequitable norms and practices by sex, age and education to inform programming. Applying community-based participatory research methodology, 680 adult respondents, selected by quota sampling, were interviewed in seven South Sudanese communities from 2009 to 2011. The verbally administered survey assessed attitudes using the Gender Equitable Men scale. Data were stratified by sex, age and education. Of 680 respondents, 352 were female, 326 were male and two did not report their sex. The majority of respondents agreed with gender inequitable household roles, but the majority disagreed with gender inequitable practices (i.e., early marriage, forced marriage and inequitable education of girls). Respondents who reported no education were more likely than those who reported any education to agree with gender inequitable practices (all p < 0.03) except for forced marriage (p = 0.07), and few significant differences were observed when these responses were stratified by sex and by age. The study reveals agreement with gender inequitable norms in the household but an overall disagreement with gender inequitable practices in sampled communities. The findings support that education of both women and men may promote gender equitable norms and practices.

  19. Influences of sex, age, and education on attitudes toward gender inequitable norms and practices in South Sudan

    PubMed Central

    Scott, Jennifer; Hacker, Michele; Averbach, Sarah; Modest, Anna M.; Cornish, Sarah; Spencer, Danielle; Murphy, Maureen; Parmar, Parveen

    2014-01-01

    Background Prolonged conflict in South Sudan exacerbated gender disparities and inequities. This study assessed differences in attitudes toward gender inequitable norms and practices by sex, age, and education to inform programming. Methods Applying community-based participatory research methodology, 680 adult respondents, selected by quota sampling, were interviewed in seven South Sudanese communities from 2009 to 2011. The verbally administered survey assessed attitudes using the Gender Equitable Men scale. Data were stratified by sex, age, and education. Results Of 680 respondents, 352 were female, 326 were male, and two did not report their sex. The majority of respondents agreed with gender inequitable household roles, but the majority disagreed with gender inequitable practices (i.e. early marriage, forced marriage, and inequitable education of girls). Respondents who reported no education were more likely than those who reported any education to agree with gender inequitable practices (all p<0.03) except for forced marriage (p=0.07), and few significant differences were observed when these responses were stratified by sex and age. Conclusion The study reveals agreement with gender inequitable norms in the household, but an overall disagreement with gender inequitable practices in sampled communities. The findings support that education of both women and men may promote gender equitable norms and practices. PMID:25026024

  20. Baseline Characteristics of Participants in the Randomized National Lung Screening Trial

    PubMed Central

    Aberle, Denise R.; Adams, Amanda M.; Berg, Christine D.; Clapp, Jonathan D.; Clingan, Kathy L.; Gareen, Ilana F.; Marcus, Pamela M.; Pinsky, Paul F.

    2010-01-01

    Background The National Lung Screening Trial (NLST), a randomized study conducted at 33 US sites, is comparing lung cancer mortality among persons screened with reduced dose helical computerized tomography and among persons screened with chest radiograph. In this article, we present characteristics of the study population. Methods Eligible participants were aged 55–74 years and were current or former smokers with a cigarette smoking history of at least 30 pack-years. Randomization was stratified by site, sex, and age. To assess representativeness of the study population, demographic characteristics of individuals from the general population who met NLST age and smoking history inclusion criteria were obtained from the Tobacco Use Supplement of the US Census Bureau Current Population Surveys. Results The NLST enrolled 53 456 persons, with 26 733 randomly assigned to chest radiograph screening and 26 723 to computerized tomography screening. Characteristics of the participants were as follows: 31 533 (59%) were men, 39 234 (73%) were younger than 65 years, 25 779 (48%) were current smokers, and 16 839 (32%) had a college or higher degree. Median cigarette exposure was 48 pack-years. Among Tobacco Use Supplement respondents who met NLST age and smoking history criteria, 59% were men, 65% were younger than 65 years, and 57% were current smokers. Median cigarette exposure among this group was 47 pack-years, and 14% had a college degree or higher. Conclusion The NLST cohort has a distribution of sex and pack-year history that is similar to the component of the general US population that meets the major NLST eligibility criteria; however, NLST participants are younger, better educated, and less likely to be current smokers. PMID:21119104

  1. Protocol for a randomized controlled trial of piano training on cognitive and psychosocial outcomes.

    PubMed

    Bugos, Jennifer

    2018-05-09

    Age-related cognitive decline and cognitive impairment represent the fastest growing health epidemic worldwide among those over 60. There is a critical need to identify effective and novel complex cognitive interventions to promote successful aging. Since piano training engages cognitive and bimanual sensorimotor processing, we hypothesize that piano training may serve as an effective cognitive intervention, as it requires sustained attention and engages an executive network that supports generalized cognition and emotional control. Here, I describe the protocol of a randomized controlled trial (RCT) to evaluate the impact of piano training on cognitive performance in adulthood, a period associated with decreased neuroplasticity. In this cluster RCT, healthy older adults (age 60-80) were recruited and screened to control for confounding variables. Eligible participants completed an initial 3-h assessment of standardized cognitive and psychosocial measures. Participants were stratified by age, education, and estimate of intelligence and randomly assigned to one of three groups: piano training, computer brain training, or a no-treatment control group. Computer brain training consisted of progressively difficult auditory cognitive exercises (Brain HQ; Posit Science, 2010). Participants assigned to training groups completed a 16-week program that met twice a week for 90 minutes. Upon program completion and at a 3-month follow-up, training participants and no-treatment controls completed a posttest visit lasting 2.5 hours. © 2018 New York Academy of Sciences.

  2. Assessing the Causal Relationship of Maternal Height on Birth Size and Gestational Age at Birth: A Mendelian Randomization Analysis.

    PubMed

    Zhang, Ge; Bacelis, Jonas; Lengyel, Candice; Teramo, Kari; Hallman, Mikko; Helgeland, Øyvind; Johansson, Stefan; Myhre, Ronny; Sengpiel, Verena; Njølstad, Pål Rasmus; Jacobsson, Bo; Muglia, Louis

    2015-08-01

    d. Limitations of this study include potential influences in causal inference by biological pleiotropy, assortative mating, and the nonrandom sampling of study subjects. Our results demonstrate that the observed association between maternal height and fetal growth measures (i.e., birth length and birth weight) is mainly defined by fetal genetics. In contrast, the association between maternal height and gestational age is more likely to be causal. In addition, our approach that utilizes the genetic score derived from the nontransmitted maternal haplotype as a genetic instrument is a novel extension to the Mendelian randomization methodology in casual inference between parental phenotype (or exposure) and outcomes in offspring.

  3. An improved algorithm of image processing technique for film thickness measurement in a horizontal stratified gas-liquid two-phase flow

    NASA Astrophysics Data System (ADS)

    Kuntoro, Hadiyan Yusuf; Hudaya, Akhmad Zidni; Dinaryanto, Okto; Majid, Akmal Irfan; Deendarlianto

    2016-06-01

    Due to the importance of the two-phase flow researches for the industrial safety analysis, many researchers developed various methods and techniques to study the two-phase flow phenomena on the industrial cases, such as in the chemical, petroleum and nuclear industries cases. One of the developing methods and techniques is image processing technique. This technique is widely used in the two-phase flow researches due to the non-intrusive capability to process a lot of visualization data which are contain many complexities. Moreover, this technique allows to capture direct-visual information data of the flow which are difficult to be captured by other methods and techniques. The main objective of this paper is to present an improved algorithm of image processing technique from the preceding algorithm for the stratified flow cases. The present algorithm can measure the film thickness (hL) of stratified flow as well as the geometrical properties of the interfacial waves with lower processing time and random-access memory (RAM) usage than the preceding algorithm. Also, the measurement results are aimed to develop a high quality database of stratified flow which is scanty. In the present work, the measurement results had a satisfactory agreement with the previous works.

  4. An improved algorithm of image processing technique for film thickness measurement in a horizontal stratified gas-liquid two-phase flow

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kuntoro, Hadiyan Yusuf, E-mail: hadiyan.y.kuntoro@mail.ugm.ac.id; Majid, Akmal Irfan; Deendarlianto, E-mail: deendarlianto@ugm.ac.id

    Due to the importance of the two-phase flow researches for the industrial safety analysis, many researchers developed various methods and techniques to study the two-phase flow phenomena on the industrial cases, such as in the chemical, petroleum and nuclear industries cases. One of the developing methods and techniques is image processing technique. This technique is widely used in the two-phase flow researches due to the non-intrusive capability to process a lot of visualization data which are contain many complexities. Moreover, this technique allows to capture direct-visual information data of the flow which are difficult to be captured by other methodsmore » and techniques. The main objective of this paper is to present an improved algorithm of image processing technique from the preceding algorithm for the stratified flow cases. The present algorithm can measure the film thickness (h{sub L}) of stratified flow as well as the geometrical properties of the interfacial waves with lower processing time and random-access memory (RAM) usage than the preceding algorithm. Also, the measurement results are aimed to develop a high quality database of stratified flow which is scanty. In the present work, the measurement results had a satisfactory agreement with the previous works.« less

  5. Use of random regression to estimate genetic parameters of temperament across an age continuum in a crossbred cattle population.

    PubMed

    Littlejohn, B P; Riley, D G; Welsh, T H; Randel, R D; Willard, S T; Vann, R C

    2018-05-12

    The objective was to estimate genetic parameters of temperament in beef cattle across an age continuum. The population consisted predominantly of Brahman-British crossbred cattle. Temperament was quantified by: 1) pen score (PS), the reaction of a calf to a single experienced evaluator on a scale of 1 to 5 (1 = calm, 5 = excitable); 2) exit velocity (EV), the rate (m/sec) at which a calf traveled 1.83 m upon exiting a squeeze chute; and 3) temperament score (TS), the numerical average of PS and EV. Covariates included days of age and proportion of Bos indicus in the calf and dam. Random regression models included the fixed effects determined from the repeated measures models, except for calf age. Likelihood ratio tests were used to determine the most appropriate random structures. In repeated measures models, the proportion of Bos indicus in the calf was positively related with each calf temperament trait (0.41 ± 0.20, 0.85 ± 0.21, and 0.57 ± 0.18 for PS, EV, and TS, respectively; P < 0.01). There was an effect of contemporary group (combinations of season, year of birth, and management group) and dam age (P < 0.001) in all models. From repeated records analyses, estimates of heritability (h2) were 0.34 ± 0.04, 0.31 ± 0.04, and 0.39 ± 0.04, while estimates of permanent environmental variance as a proportion of the phenotypic variance (c2) were 0.30 ± 0.04, 0.31 ± 0.03, and 0.34 ± 0.04 for PS, EV, and TS, respectively. Quadratic additive genetic random regressions on Legendre polynomials of age were significant for all traits. Quadratic permanent environmental random regressions were significant for PS and TS, but linear permanent environmental random regressions were significant for EV. Random regression results suggested that these components change across the age dimension of these data. There appeared to be an increasing influence of permanent environmental effects and decreasing influence of additive genetic effects corresponding to increasing calf age

  6. Random sampling causes the low reproducibility of rare eukaryotic OTUs in Illumina COI metabarcoding.

    PubMed

    Leray, Matthieu; Knowlton, Nancy

    2017-01-01

    DNA metabarcoding, the PCR-based profiling of natural communities, is becoming the method of choice for biodiversity monitoring because it circumvents some of the limitations inherent to traditional ecological surveys. However, potential sources of bias that can affect the reproducibility of this method remain to be quantified. The interpretation of differences in patterns of sequence abundance and the ecological relevance of rare sequences remain particularly uncertain. Here we used one artificial mock community to explore the significance of abundance patterns and disentangle the effects of two potential biases on data reproducibility: indexed PCR primers and random sampling during Illumina MiSeq sequencing. We amplified a short fragment of the mitochondrial Cytochrome c Oxidase Subunit I (COI) for a single mock sample containing equimolar amounts of total genomic DNA from 34 marine invertebrates belonging to six phyla. We used seven indexed broad-range primers and sequenced the resulting library on two consecutive Illumina MiSeq runs. The total number of Operational Taxonomic Units (OTUs) was ∼4 times higher than expected based on the composition of the mock sample. Moreover, the total number of reads for the 34 components of the mock sample differed by up to three orders of magnitude. However, 79 out of 86 of the unexpected OTUs were represented by <10 sequences that did not appear consistently across replicates. Our data suggest that random sampling of rare OTUs (e.g., small associated fauna such as parasites) accounted for most of variation in OTU presence-absence, whereas biases associated with indexed PCRs accounted for a larger amount of variation in relative abundance patterns. These results suggest that random sampling during sequencing leads to the low reproducibility of rare OTUs. We suggest that the strategy for handling rare OTUs should depend on the objectives of the study. Systematic removal of rare OTUs may avoid inflating diversity based on

  7. Random sampling of constrained phylogenies: conducting phylogenetic analyses when the phylogeny is partially known.

    PubMed

    Housworth, E A; Martins, E P

    2001-01-01

    Statistical randomization tests in evolutionary biology often require a set of random, computer-generated trees. For example, earlier studies have shown how large numbers of computer-generated trees can be used to conduct phylogenetic comparative analyses even when the phylogeny is uncertain or unknown. These methods were limited, however, in that (in the absence of molecular sequence or other data) they allowed users to assume that no phylogenetic information was available or that all possible trees were known. Intermediate situations where only a taxonomy or other limited phylogenetic information (e.g., polytomies) are available are technically more difficult. The current study describes a procedure for generating random samples of phylogenies while incorporating limited phylogenetic information (e.g., four taxa belong together in a subclade). The procedure can be used to conduct comparative analyses when the phylogeny is only partially resolved or can be used in other randomization tests in which large numbers of possible phylogenies are needed.

  8. Characterizing stand-level forest canopy cover and height using Landsat time series, samples of airborne LiDAR, and the Random Forest algorithm

    NASA Astrophysics Data System (ADS)

    Ahmed, Oumer S.; Franklin, Steven E.; Wulder, Michael A.; White, Joanne C.

    2015-03-01

    Many forest management activities, including the development of forest inventories, require spatially detailed forest canopy cover and height data. Among the various remote sensing technologies, LiDAR (Light Detection and Ranging) offers the most accurate and consistent means for obtaining reliable canopy structure measurements. A potential solution to reduce the cost of LiDAR data, is to integrate transects (samples) of LiDAR data with frequently acquired and spatially comprehensive optical remotely sensed data. Although multiple regression is commonly used for such modeling, often it does not fully capture the complex relationships between forest structure variables. This study investigates the potential of Random Forest (RF), a machine learning technique, to estimate LiDAR measured canopy structure using a time series of Landsat imagery. The study is implemented over a 2600 ha area of industrially managed coastal temperate forests on Vancouver Island, British Columbia, Canada. We implemented a trajectory-based approach to time series analysis that generates time since disturbance (TSD) and disturbance intensity information for each pixel and we used this information to stratify the forest land base into two strata: mature forests and young forests. Canopy cover and height for three forest classes (i.e. mature, young and mature and young (combined)) were modeled separately using multiple regression and Random Forest (RF) techniques. For all forest classes, the RF models provided improved estimates relative to the multiple regression models. The lowest validation error was obtained for the mature forest strata in a RF model (R2 = 0.88, RMSE = 2.39 m and bias = -0.16 for canopy height; R2 = 0.72, RMSE = 0.068% and bias = -0.0049 for canopy cover). This study demonstrates the value of using disturbance and successional history to inform estimates of canopy structure and obtain improved estimates of forest canopy cover and height using the RF algorithm.

  9. Atomoxetine Does Not Alter Cocaine Use in Cocaine Dependent Individuals: A Double Blind Randomized Trial

    PubMed Central

    Middleton, Lisa S.; Wong, Conrad J.; Nuzzo, Paul A.; Campbell, Charles L.; Rush, Craig R.; Lofwall, Michelle R.

    2016-01-01

    Background Cocaine abuse continues to be a significant public health problem associated with morbidity and mortality. To date, no pharmacotherapeutic approach has proven effective for treating cocaine use disorders. Preclinical and clinical evidence suggests that noradrenergic activity may play a role in mediating some effects of cocaine and may be a rational target for treatment. Methods This double blind, placebo-controlled randomized, parallel group, 12-week outpatient clinical trial enrolled cocaine dependent individuals seeking treatment to examine the potential efficacy of the selective norepinephrine reuptake inhibitor, atomoxetine (80 mg/day; p.o.; n=25), compared to placebo (n=25). Subjects were initially stratified on cocaine use (<15 days or ≥15 days of the last 30), age and race using urn randomization. Attendance, medication adherence and study compliance were reinforced with contingency management, and weekly counseling was offered. An array of measures (vital signs, laboratory chemistries, cognitive and psychomotor tests, cocaine craving and urine samples for drug testing) was collected throughout the study and at follow-up. Results Survival analysis revealed no differences in study retention between the two groups, with approximately 56% of subjects completing the 12-week study (Cox analysis X2=.72; p=.40; Hazard Ratio 1.48 [CI 0.62–3.39]). GEE analysis of the proportion of urine samples positive for benzoylecgonine, a cocaine metabolite, revealed no differences between the atomoxetine and placebo groups (X2=0.2, p=.66; OR=0.89 [95% CI 0.41 – 1.74). Atomoxetine was generally well tolerated in this population. Conclusions These data provide no support for the utility of atomoxetine in the treatment of cocaine dependence. PMID:23200303

  10. Comparing the performance of cluster random sampling and integrated threshold mapping for targeting trachoma control, using computer simulation.

    PubMed

    Smith, Jennifer L; Sturrock, Hugh J W; Olives, Casey; Solomon, Anthony W; Brooker, Simon J

    2013-01-01

    Implementation of trachoma control strategies requires reliable district-level estimates of trachomatous inflammation-follicular (TF), generally collected using the recommended gold-standard cluster randomized surveys (CRS). Integrated Threshold Mapping (ITM) has been proposed as an integrated and cost-effective means of rapidly surveying trachoma in order to classify districts according to treatment thresholds. ITM differs from CRS in a number of important ways, including the use of a school-based sampling platform for children aged 1-9 and a different age distribution of participants. This study uses computerised sampling simulations to compare the performance of these survey designs and evaluate the impact of varying key parameters. Realistic pseudo gold standard data for 100 districts were generated that maintained the relative risk of disease between important sub-groups and incorporated empirical estimates of disease clustering at the household, village and district level. To simulate the different sampling approaches, 20 clusters were selected from each district, with individuals sampled according to the protocol for ITM and CRS. Results showed that ITM generally under-estimated the true prevalence of TF over a range of epidemiological settings and introduced more district misclassification according to treatment thresholds than did CRS. However, the extent of underestimation and resulting misclassification was found to be dependent on three main factors: (i) the district prevalence of TF; (ii) the relative risk of TF between enrolled and non-enrolled children within clusters; and (iii) the enrollment rate in schools. Although in some contexts the two methodologies may be equivalent, ITM can introduce a bias-dependent shift as prevalence of TF increases, resulting in a greater risk of misclassification around treatment thresholds. In addition to strengthening the evidence base around choice of trachoma survey methodologies, this study illustrates the use of

  11. Discrete element method (DEM) simulations of stratified sampling during solid dosage form manufacturing.

    PubMed

    Hancock, Bruno C; Ketterhagen, William R

    2011-10-14

    Discrete element model (DEM) simulations of the discharge of powders from hoppers under gravity were analyzed to provide estimates of dosage form content uniformity during the manufacture of solid dosage forms (tablets and capsules). For a system that exhibits moderate segregation the effects of sample size, number, and location within the batch were determined. The various sampling approaches were compared to current best-practices for sampling described in the Product Quality Research Institute (PQRI) Blend Uniformity Working Group (BUWG) guidelines. Sampling uniformly across the discharge process gave the most accurate results with respect to identifying segregation trends. Sigmoidal sampling (as recommended in the PQRI BUWG guidelines) tended to overestimate potential segregation issues, whereas truncated sampling (common in industrial practice) tended to underestimate them. The size of the sample had a major effect on the absolute potency RSD. The number of sampling locations (10 vs. 20) had very little effect on the trends in the data, and the number of samples analyzed at each location (1 vs. 3 vs. 7) had only a small effect for the sampling conditions examined. The results of this work provide greater understanding of the effect of different sampling approaches on the measured content uniformity of real dosage forms, and can help to guide the choice of appropriate sampling protocols. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. The effect of existing turbulence on stratified shear instability

    NASA Astrophysics Data System (ADS)

    Kaminski, Alexis; Smyth, William

    2017-11-01

    Ocean turbulence is an essential process governing, for example, heat uptake by the ocean. In the stably-stratified ocean interior, this turbulence occurs in discrete events driven by vertical variations of the horizontal velocity. Typically, these events have been modelled by assuming an initially laminar stratified shear flow which develops wavelike instabilities, becomes fully turbulent, and then relaminarizes into a stable state. However, in the real ocean there is always some level of turbulence left over from previous events, and it is not yet understood how this turbulence impacts the evolution of future mixing events. Here, we perform a series of direct numerical simulations of turbulent events developing in stratified shear flows that are already at least weakly turbulent. We do so by varying the amplitude of the initial perturbations, and examine the subsequent development of the instability and the impact on the resulting turbulent fluxes. This work is supported by NSF Grant OCE1537173.

  13. TemperSAT: A new efficient fair-sampling random k-SAT solver

    NASA Astrophysics Data System (ADS)

    Fang, Chao; Zhu, Zheng; Katzgraber, Helmut G.

    The set membership problem is of great importance to many applications and, in particular, database searches for target groups. Recently, an approach to speed up set membership searches based on the NP-hard constraint-satisfaction problem (random k-SAT) has been developed. However, the bottleneck of the approach lies in finding the solution to a large SAT formula efficiently and, in particular, a large number of independent solutions is needed to reduce the probability of false positives. Unfortunately, traditional random k-SAT solvers such as WalkSAT are biased when seeking solutions to the Boolean formulas. By porting parallel tempering Monte Carlo to the sampling of binary optimization problems, we introduce a new algorithm (TemperSAT) whose performance is comparable to current state-of-the-art SAT solvers for large k with the added benefit that theoretically it can find many independent solutions quickly. We illustrate our results by comparing to the currently fastest implementation of WalkSAT, WalkSATlm.

  14. Assessing sample representativeness in randomized controlled trials: application to the National Institute of Drug Abuse Clinical Trials Network.

    PubMed

    Susukida, Ryoko; Crum, Rosa M; Stuart, Elizabeth A; Ebnesajjad, Cyrus; Mojtabai, Ramin

    2016-07-01

    To compare the characteristics of individuals participating in randomized controlled trials (RCTs) of treatments of substance use disorder (SUD) with individuals receiving treatment in usual care settings, and to provide a summary quantitative measure of differences between characteristics of these two groups of individuals using propensity score methods. Design Analyses using data from RCT samples from the National Institute of Drug Abuse Clinical Trials Network (CTN) and target populations of patients drawn from the Treatment Episodes Data Set-Admissions (TEDS-A). Settings Multiple clinical trial sites and nation-wide usual SUD treatment settings in the United States. A total of 3592 individuals from 10 CTN samples and 1 602 226 individuals selected from TEDS-A between 2001 and 2009. Measurements The propensity scores for enrolling in the RCTs were computed based on the following nine observable characteristics: sex, race/ethnicity, age, education, employment status, marital status, admission to treatment through criminal justice, intravenous drug use and the number of prior treatments. Findings The proportion of those with ≥ 12 years of education and the proportion of those who had full-time jobs were significantly higher among RCT samples than among target populations (in seven and nine trials, respectively, at P < 0.001). The pooled difference in the mean propensity scores between the RCTs and the target population was 1.54 standard deviations and was statistically significant at P < 0.001. In the United States, individuals recruited into randomized controlled trials of substance use disorder treatments appear to be very different from individuals receiving treatment in usual care settings. Notably, RCT participants tend to have more years of education and a greater likelihood of full-time work compared with people receiving care in usual care settings. © 2016 Society for the Study of Addiction.

  15. A comparison of respondent-driven and venue-based sampling of female sex workers in Liuzhou, China

    PubMed Central

    Weir, Sharon S; Merli, M Giovanna; Li, Jing; Gandhi, Anisha D; Neely, William W; Edwards, Jessie K; Suchindran, Chirayath M; Henderson, Gail E; Chen, Xiang-Sheng

    2012-01-01

    Objectives To compare two methods for sampling female sex workers (FSWs) for bio-behavioural surveillance. We compared the populations of sex workers recruited by the venue-based Priorities for Local AIDS Control Efforts (PLACE) method and a concurrently implemented network-based sampling method, respondent-driven sampling (RDS), in Liuzhou, China. Methods For the PLACE protocol, all female workers at a stratified random sample of venues identified as places where people meet new sexual partners were interviewed and tested for syphilis. Female workers who reported sex work in the past 4 weeks were categorised as FSWs. RDS used peer recruitment and chain referral to obtain a sample of FSWs. Data were collected between October 2009 and January 2010. We compared the socio-demographic characteristics and the percentage with a positive syphilis test of FSWs recruited by PLACE and RDS. Results The prevalence of a positive syphilis test was 24% among FSWs recruited by PLACE and 8.5% among those recruited by RDS and tested (prevalence ratio 3.3; 95% CI 1.5 to 7.2). Socio-demographic characteristics (age, residence and monthly income) also varied by sampling method. PLACE recruited fewer FSWs than RDS (161 vs 583), was more labour-intensive and had difficulty gaining access to some venues. RDS was more likely to recruit from areas near the RDS office and from large low prevalence entertainment venues. Conclusions Surveillance protocols using different sampling methods can obtain different estimates of prevalence and population characteristics. Venue-based and network-based methods each have strengths and limitations reflecting differences in design and assumptions. We recommend that more research be conducted on measuring bias in bio-behavioural surveillance. PMID:23172350

  16. A tale of two "forests": random forest machine learning AIDS tropical forest carbon mapping.

    PubMed

    Mascaro, Joseph; Asner, Gregory P; Knapp, David E; Kennedy-Bowdoin, Ty; Martin, Roberta E; Anderson, Christopher; Higgins, Mark; Chadwick, K Dana

    2014-01-01

    Accurate and spatially-explicit maps of tropical forest carbon stocks are needed to implement carbon offset mechanisms such as REDD+ (Reduced Deforestation and Degradation Plus). The Random Forest machine learning algorithm may aid carbon mapping applications using remotely-sensed data. However, Random Forest has never been compared to traditional and potentially more reliable techniques such as regionally stratified sampling and upscaling, and it has rarely been employed with spatial data. Here, we evaluated the performance of Random Forest in upscaling airborne LiDAR (Light Detection and Ranging)-based carbon estimates compared to the stratification approach over a 16-million hectare focal area of the Western Amazon. We considered two runs of Random Forest, both with and without spatial contextual modeling by including--in the latter case--x, and y position directly in the model. In each case, we set aside 8 million hectares (i.e., half of the focal area) for validation; this rigorous test of Random Forest went above and beyond the internal validation normally compiled by the algorithm (i.e., called "out-of-bag"), which proved insufficient for this spatial application. In this heterogeneous region of Northern Peru, the model with spatial context was the best preforming run of Random Forest, and explained 59% of LiDAR-based carbon estimates within the validation area, compared to 37% for stratification or 43% by Random Forest without spatial context. With the 60% improvement in explained variation, RMSE against validation LiDAR samples improved from 33 to 26 Mg C ha(-1) when using Random Forest with spatial context. Our results suggest that spatial context should be considered when using Random Forest, and that doing so may result in substantially improved carbon stock modeling for purposes of climate change mitigation.

  17. Sedimentary Fabrics of Stratified Slope Deposits at a Site near Hoover's Camp, Shenandoah National Park, Virginia

    USGS Publications Warehouse

    Smoot, Joseph P.

    2004-01-01

    An outcrop of stratified slope deposits in Shenandoah National Park is described in detail. The Pleistocene age deposits are comprised of a mixture of clay to cobbles defining a series of offlapping wedges. Elongate clasts are oriented parallel to wedge boundaries except at the toe of the wedge, where they are oriented nearly vertical. The wedges represent sedimentation by freeze-thaw of ground ice. Thin layers of pebbly sand separate matrix-rich wedge deposits, which represent sheetfloods during periods of thaw. Thicker sand layers and lenses of clay are placed upslope of coarse-grained wedge fronts. This association represents ponding of water around the solifluction lobe topography during warm periods. Stratified slope deposits at an outcrop at a higher elevation lack the sandy sheetflood and pond deposits, whereas sheetflood fabrics dominate deposits at a lower elevation. These variations are attributed to differences in temperature at the different elevations.

  18. Analysis of the machinery and intermediates of the 5hmC-mediated DNA demethylation pathway in aging on samples from the MARK-AGE Study

    PubMed Central

    Valentini, Elisabetta; Zampieri, Michele; Malavolta, Marco; Bacalini, Maria Giulia; Calabrese, Roberta; Guastafierro, Tiziana; Reale, Anna; Franceschi, Claudio; Hervonen, Antti; Koller, Bernhard; Bernhardt, Jürgen; Slagboom, P. Eline; Toussaint, Olivier; Sikora, Ewa; Gonos, Efstathios S.; Breusing, Nicolle; Grune, Tilman; Jansen, Eugène; Dollé, Martijn E.T.; Moreno-Villanueva, María; Sindlinger, Thilo; Bürkle, Alexander; Ciccarone, Fabio; Caiafa, Paola

    2016-01-01

    Gradual changes in the DNA methylation landscape occur throughout aging virtually in all human tissues. A widespread reduction of 5-methylcytosine (5mC), associated with highly reproducible site-specific hypermethylation, characterizes the genome in aging. Therefore, an equilibrium seems to exist between general and directional deregulating events concerning DNA methylation controllers, which may underpin the age-related epigenetic changes. In this context, 5mC-hydroxylases (TET enzymes) are new potential players. In fact, TETs catalyze the stepwise oxidation of 5mC to 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC), driving the DNA demethylation process based on thymine DNA glycosylase (TDG)-mediated DNA repair pathway. The present paper reports the expression of DNA hydroxymethylation components, the levels of 5hmC and of its derivatives in peripheral blood mononuclear cells of age-stratified donors recruited in several European countries in the context of the EU Project ‘MARK-AGE’. The results provide evidence for an age-related decline of TET1, TET3 and TDG gene expression along with a decrease of 5hmC and an accumulation of 5caC. These associations were independent of confounding variables, including recruitment center, gender and leukocyte composition. The observed impairment of 5hmC-mediated DNA demethylation pathway in blood cells may lead to aberrant transcriptional programs in the elderly. PMID:27587280

  19. Sexual activity and perceived health among Finnish middle-aged women

    PubMed Central

    Ojanlatva, Ansa; Mäkinen, Juha; Helenius, Hans; Korkeila, Katariina; Sundell, Jari; Rautava, Päivi

    2006-01-01

    Background An increasing awareness of the need to address sexual and orgasm experiences as part of life quality and an understanding of the great individual differences between women play roles in women's health and medical care across the specialities. Information is lacking as to how negative attitude toward self (NATS) and performance impairment (PI) are associated with sexual activity of middle-aged women. We examined the associations of sexual experience, orgasm experience, and lack of sexual desire with perceived health and potential explanatory variables of NATS and PI. Methods Questionnaire was mailed to 2 population-based random samples of menopausal or soon-to-be menopausal women (n = 5510, 70% response) stratified according to age (42–46 and 52–56 years). In multivariate analyses of the associations with the outcome variables, perceived health, NATS, and PI were used as covariates in 6 models in which exercise, menstrual symptoms, and illness indicators were taken into account as well. Results Sexual activity variables were associated with perceived health. When present, NATS formed associations with sexual and orgasm experiences, whereas strenuous exercise formed associations with orgasm among 42–46-year-old women alone. Strenuous exercise was not associated with orgasm experience among older women. Conclusion NATS and PI are closely tied to orgasm experiences and the meaning of the roles needs to be exposed. Sexual activity deserves to be addressed more actively in patient contact at least with perimenopausal women. PMID:16686959

  20. The silvicultural implications of age patterns in two southern pine stands after 72 years of uneven-aged management

    Treesearch

    Don C. Bragg; James M. Guldin

    2015-01-01

    A randomized sample of 250 loblolly (Pinus taeda L.) and shortleaf (Pinus echinata Mill.) pine ring counts was collected from the Good and Poor Farm Forestry compartments on the Crossett Experimental Forest. These mature, pine-dominated stands have been managed using uneven-aged silviculture since 1937. Our sample shows that both...

  1. THE SELECTION OF A NATIONAL RANDOM SAMPLE OF TEACHERS FOR EXPERIMENTAL CURRICULUM EVALUATION.

    ERIC Educational Resources Information Center

    WELCH, WAYNE W.; AND OTHERS

    MEMBERS OF THE EVALUATION SECTION OF HARVARD PROJECT PHYSICS, DESCRIBING WHAT IS SAID TO BE THE FIRST ATTEMPT TO SELECT A NATIONAL RANDOM SAMPLE OF (HIGH SCHOOL PHYSICS) TEACHERS, LIST THE STEPS AS (1) PURCHASE OF A LIST OF PHYSICS TEACHERS FROM THE NATIONAL SCIENCE TEACHERS ASSOCIATION (MOST COMPLETE AVAILABLE), (2) SELECTION OF 136 NAMES BY A…

  2. Community-wide promotion of physical activity in middle-aged and older Japanese: a 3-year evaluation of a cluster randomized trial.

    PubMed

    Kamada, Masamitsu; Kitayuguchi, Jun; Abe, Takafumi; Taguri, Masataka; Inoue, Shigeru; Ishikawa, Yoshiki; Harada, Kazuhiro; Lee, I-Min; Bauman, Adrian; Miyachi, Motohiko

    2015-06-23

    Promotion of physical activity (PA) is a key strategy to prevent non-communicable diseases. However, evidence on the effectiveness of community-wide interventions (CWIs) for promoting PA is limited. To evaluate the effectiveness of a 3-year CWI for promoting PA in middle-aged and older adults compared with usual public health services. This study is an extension to an original 1-year investigation study. Cluster randomized controlled trial with community as unit of randomization and individual as unit of analysis. 12 communities in Unnan, Japan were randomly allocated to the intervention (9) or the control (3). Additionally intervention communities were randomly allocated to aerobic activity promotion (Group A), flexibility and muscle-strengthening activities promotion (Group FM), or aerobic, flexibility, and muscle-strengthening activities promotion (Group AFM), each consisting of three communities. Randomly-sampled 4414 residents aged 40 to 79 years responded to the baseline survey (74%), and were analyzed in 2013-2014. A 3-year CWI based on social marketing, to promote PA from 2009 to 2012. The primary outcome was a change in regular aerobic, flexibility, and/or muscle-strengthening activities, defined by (1) engaging in 150 mins/week or more of walking, (2) engaging in daily flexibility activity, or (3) engaging 2 or more days/week in muscle-strengthening activities, evaluated at the individual level. Secondary outcomes were changes in specific types of PA and musculoskeletal pain. Outcomes were measured at baseline and at 1 and 3 years (2009, 2010, and 2012). The CWI did not significantly increase the proportion of adults who reached recommended levels of aerobic, flexibility, and/or muscle-strengthening activities (adjusted change difference = 1.6% [95% CI: -3.5, 6.6]). In the subgroup analysis, compared to the controls, adults doing flexibility activity daily significantly increased in Group FM (6.3% [95% CI: 1.9, 10.7]). In Group A and AFM for PA

  3. Effect of Trospium Chloride on Cognitive Function in Women Aged 50 and Older: A Randomized Trial.

    PubMed

    Geller, Elizabeth J; Dumond, Julie B; Bowling, J Michael; Khandelwal, Christine M; Wu, Jennifer M; Busby-Whitehead, Jan; Kaufer, Daniel I

    This study aimed to investigate the effect of trospium chloride on cognitive function in postmenopausal women treated for overactive bladder (OAB). Randomized double-blind placebo-controlled trial conducted from April 2013 to April 2015. Women aged 50 years or older seeking treatment for OAB were randomized to either trospium chloride XR 60 mg daily or placebo. Baseline cognitive function was assessed via Hopkins Verbal Learning Test-Revised (HVLT-R), Mini Mental Status Exam, Mini Mental Status X, Digit Span, Trails A, Trails B, and Epworth Sleepiness Scale. Cognitive function was reassessed at week 1 and week 4. A priori power analysis determined that 21 subjects were needed per group. Although 59 women were enrolled and randomized (28 trospium and 31 placebo), 45 completed assessment (21 trospium and 24 placebo). Mean age was 68 years, 78% were white, and 44% had previously taken OAB medication. For the primary outcome, there was no difference in HVLT-R total score between trospium and placebo groups at week 4 (P = 0.29). There were also no differences based on the other cognitive tests. There was a correlation between age and the following week-4 tests: HVLT-R total score (r = -0.3, P = 0.02), HVLT-R total recall subscale (r = -0.4, P = 0.007), Trails A (r = 0.4, P = 0.002), and Trails B (r = 0.4, P = 0.004). A linear regression model found that HVLT-R total score decreased by 0.372 points for each increased year of age. In women aged 50 years and older, there were no changes in cognitive function between those taking trospium and placebo. Cognitive function was correlated with age.

  4. Randomized Trial of Labor Induction in Women 35 Years of Age or Older.

    PubMed

    Walker, Kate F; Bugg, George J; Macpherson, Marion; McCormick, Carol; Grace, Nicky; Wildsmith, Chris; Bradshaw, Lucy; Smith, Gordon C S; Thornton, James G

    2016-03-03

    The risk of antepartum stillbirth at term is higher among women 35 years of age or older than among younger women. Labor induction may reduce the risk of stillbirth, but it also may increase the risk of cesarean delivery, which already is common in this older age group. We conducted a randomized, controlled trial involving primigravid women who were 35 years of age or older. Women were randomly assigned to labor induction between 39 weeks 0 days and 39 weeks 6 days of gestation or to expectant management (i.e., waiting until the spontaneous onset of labor or until the development of a medical problem that mandated induction). The primary outcome was cesarean delivery. The trial was not designed or powered to assess the effects of labor induction on stillbirth. A total of 619 women underwent randomization. In an intention-to-treat analysis, there were no significant between-group differences in the percentage of women who underwent a cesarean section (98 of 304 women in the induction group [32%] and 103 of 314 women in the expectant-management group [33%]; relative risk, 0.99; 95% confidence interval [CI], 0.87 to 1.14) or in the percentage of women who had a vaginal delivery with the use of forceps or vacuum (115 of 304 women [38%] and 104 of 314 women [33%], respectively; relative risk, 1.30; 95% CI, 0.96 to 1.77). There were no maternal or infant deaths and no significant between-group differences in the women's experience of childbirth or in the frequency of adverse maternal or neonatal outcomes. Among women of advanced maternal age, induction of labor at 39 weeks of gestation, as compared with expectant management, had no significant effect on the rate of cesarean section and no adverse short-term effects on maternal or neonatal outcomes. (Funded by the Research for Patient Benefit Programme of the National Institute for Health Research; Current Controlled Trials number, ISRCTN11517275.).

  5. Nonmedical influences on medical decision making: an experimental technique using videotapes, factorial design, and survey sampling.

    PubMed Central

    Feldman, H A; McKinlay, J B; Potter, D A; Freund, K M; Burns, R B; Moskowitz, M A; Kasten, L E

    1997-01-01

    OBJECTIVE: To study nonmedical influences on the doctor-patient interaction. A technique using simulated patients and "real" doctors is described. DATA SOURCES: A random sample of physicians, stratified on such characteristics as demographics, specialty, or experience, and selected from commercial and professional listings. STUDY DESIGN: A medical appointment is depicted on videotape by professional actors. The patient's presenting complaint (e.g., chest pain) allows a range of valid interpretation. Several alternative versions are taped, featuring the same script with patient-actors of different age, sex, race, or other characteristics. Fractional factorial design is used to select a balanced subset of patient characteristics, reducing costs without biasing the outcome. DATA COLLECTION: Each physician is shown one version of the videotape appointment and is asked to describe how he or she would diagnose or treat such a patient. PRINCIPAL FINDINGS: Two studies using this technique have been completed to date, one involving chest pain and dyspnea and the other involving breast cancer. The factorial design provided sufficient power, despite limited sample size, to demonstrate with statistical significance various influences of the experimental and stratification variables, including the patient's gender and age and the physician's experience. Persistent recruitment produced a high response rate, minimizing selection bias and enhancing validity. CONCLUSION: These techniques permit us to determine, with a degree of control unattainable in observational studies, whether medical decisions as described by actual physicians and drawn from a demographic or professional group of interest, are influenced by a prescribed set of nonmedical factors. PMID:9240285

  6. Serum and erythrocyte folate status of New Zealand women of childbearing age following a countrywide voluntary programme by the baking industry to fortify bread with folic acid.

    PubMed

    Bradbury, Kathryn E; Williams, Sheila M; Mann, Jim I; Oey, Indrawati; Aitchison, Cindy; Parnell, Winsome; Fleming, Liz; Brown, Rachel C; Skeaff, C Murray

    2016-11-01

    To estimate the folate status of New Zealand women of childbearing age following the introduction, in 2010, of a new voluntary folic acid fortification of bread programme. The 2011 Folate and Women's Health Survey was a cross-sectional survey of women aged 18-44 years carried out in 2011. The survey used a stratified random sampling technique with the Electoral Roll as the sampling frame. Women were asked about consumption of folic-acid-fortified breads and breakfast cereals in a telephone interview. During a clinic visit, blood was collected for serum and erythrocyte folate measurement by microbiological assay. A North Island (Wellington) and South Island (Dunedin) city centre in New Zealand. Two hundred and eighty-eight women, of whom 278 completed a clinic visit. Geometric mean serum and erythrocyte folate concentrations were 30 nmol/l and 996 nmol/l, respectively. Folate status was 30-40 % higher compared with women of childbearing age sampled as part of a national survey in 2008/09, prior to the introduction of the voluntary folic acid bread fortification programme. In the 2011 Folate and Women's Health Survey, reported consumption of fortified bread and fortified breakfast cereal in the past week was associated with 25 % (P=0·01) and 15 % (P=0·04) higher serum folate concentrations, respectively. Serum and erythrocyte folate concentrations have increased in New Zealand women of childbearing age since the number of folic-acid-fortified breads was increased voluntarily in 2010. Consumption of fortified breads and breakfast cereals was associated with a higher folate status.

  7. Sampling design for an integrated socioeconomic and ecological survey by using satellite remote sensing and ordination

    PubMed Central

    Binford, Michael W.; Lee, Tae Jeong; Townsend, Robert M.

    2004-01-01

    Environmental variability is an important risk factor in rural agricultural communities. Testing models requires empirical sampling that generates data that are representative in both economic and ecological domains. Detrended correspondence analysis of satellite remote sensing data were used to design an effective low-cost sampling protocol for a field study to create an integrated socioeconomic and ecological database when no prior information on ecology of the survey area existed. We stratified the sample for the selection of tambons from various preselected provinces in Thailand based on factor analysis of spectral land-cover classes derived from satellite data. We conducted the survey for the sampled villages in the chosen tambons. The resulting data capture interesting variations in soil productivity and in the timing of good and bad years, which a purely random sample would likely have missed. Thus, this database will allow tests of hypotheses concerning the effect of credit on productivity, the sharing of idiosyncratic risks, and the economic influence of environmental variability. PMID:15254298

  8. A new approach to modelling schistosomiasis transmission based on stratified worm burden.

    PubMed

    Gurarie, D; King, C H; Wang, X

    2010-11-01

    Multiple factors affect schistosomiasis transmission in distributed meta-population systems including age, behaviour, and environment. The traditional approach to modelling macroparasite transmission often exploits the 'mean worm burden' (MWB) formulation for human hosts. However, typical worm distribution in humans is overdispersed, and classic models either ignore this characteristic or make ad hoc assumptions about its pattern (e.g., by assuming a negative binomial distribution). Such oversimplifications can give wrong predictions for the impact of control interventions. We propose a new modelling approach to macro-parasite transmission by stratifying human populations according to worm burden, and replacing MWB dynamics with that of 'population strata'. We developed proper calibration procedures for such multi-component systems, based on typical epidemiological and demographic field data, and implemented them using Wolfram Mathematica. Model programming and calibration proved to be straightforward. Our calibrated system provided good agreement with the individual level field data from the Msambweni region of eastern Kenya. The Stratified Worm Burden (SWB) approach offers many advantages, in that it accounts naturally for overdispersion and accommodates other important factors and measures of human infection and demographics. Future work will apply this model and methodology to evaluate innovative control intervention strategies, including expanded drug treatment programmes proposed by the World Health Organization and its partners.

  9. Randomization of grab-sampling strategies for estimating the annual exposure of U miners to Rn daughters.

    PubMed

    Borak, T B

    1986-04-01

    Periodic grab sampling in combination with time-of-occupancy surveys has been the accepted procedure for estimating the annual exposure of underground U miners to Rn daughters. Temporal variations in the concentration of potential alpha energy in the mine generate uncertainties in this process. A system to randomize the selection of locations for measurement is described which can reduce uncertainties and eliminate systematic biases in the data. In general, a sample frequency of 50 measurements per year is sufficient to satisfy the criteria that the annual exposure be determined in working level months to within +/- 50% of the true value with a 95% level of confidence. Suggestions for implementing this randomization scheme are presented.

  10. Optimal Stratification of Item Pools in a-Stratified Computerized Adaptive Testing.

    ERIC Educational Resources Information Center

    Chang, Hua-Hua; van der Linden, Wim J.

    2003-01-01

    Developed a method based on 0-1 linear programming to stratify an item pool optimally for use in alpha-stratified adaptive testing. Applied the method to a previous item pool from the computerized adaptive test of the Graduate Record Examinations. Results show the new method performs well in practical situations. (SLD)

  11. A systematic examination of a random sampling strategy for source apportionment calculations.

    PubMed

    Andersson, August

    2011-12-15

    Estimating the relative contributions from multiple potential sources of a specific component in a mixed environmental matrix is a general challenge in diverse fields such as atmospheric, environmental and earth sciences. Perhaps the most common strategy for tackling such problems is by setting up a system of linear equations for the fractional influence of different sources. Even though an algebraic solution of this approach is possible for the common situation with N+1 sources and N source markers, such methodology introduces a bias, since it is implicitly assumed that the calculated fractions and the corresponding uncertainties are independent of the variability of the source distributions. Here, a random sampling (RS) strategy for accounting for such statistical bias is examined by investigating rationally designed synthetic data sets. This random sampling methodology is found to be robust and accurate with respect to reproducibility and predictability. This method is also compared to a numerical integration solution for a two-source situation where source variability also is included. A general observation from this examination is that the variability of the source profiles not only affects the calculated precision but also the mean/median source contributions. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Absolute ages from crater statistics: Using radiometric ages of Martian samples for determining the Martian cratering chronology

    NASA Technical Reports Server (NTRS)

    Neukum, G.

    1988-01-01

    In the absence of dates derived from rock samples, impact crater frequencies are commonly used to date Martian surface units. All models for absolute dating rely on the lunar cratering chronology and on the validity of its extrapolation to Martian conditions. Starting from somewhat different lunar chronologies, rather different Martian cratering chronologies are found in the literature. Currently favored models are compared. The differences at old ages are significant, the differences at younger ages are considerable and give absolute ages for the same crater frequencies as different as a factor of 3. The total uncertainty could be much higher, though, since the ratio of lunar to Martian cratering rate which is of basic importance in the models is believed to be known no better than within a factor of 2. Thus, it is of crucial importance for understanding the the evolution of Mars and determining the sequence of events to establish an unambiguous Martian cratering chronology from crater statistics in combination with clean radiometric ages of returned Martian samples. For the dating goal, rocks should be as pristine as possible from a geologically simple area with a one-stage emplacement history of the local formation. A minimum of at least one highland site for old ages, two intermediate-aged sites, and one very young site is needed.

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

    PubMed Central

    2014-01-01

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

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

    PubMed

    McGregor, Marion; Puhl, Aaron A; Reinhart, Christine; Injeyan, H Stephen; Soave, David

    2014-02-10

    As health care has increased in complexity and health care teams have been offered as a solution, so too is there an increased need for stronger interprofessional collaboration. However the intraprofessional factions that exist within every profession challenge interprofessional communication through contrary paradigms. As a contender in the conservative spinal health care market, factions within chiropractic that result in unorthodox practice behaviours may compromise interprofessional relations and that profession's progress toward institutionalization. The purpose of this investigation was to quantify the professional stratification among Canadian chiropractic practitioners and evaluate the practice perceptions of those factions. A stratified random sample of 740 Canadian chiropractors was surveyed to determine faction membership and how professional stratification could be related to views that could be considered unorthodox to current evidence-based care and guidelines. Stratification in practice behaviours is a stated concern of mainstream medicine when considering interprofessional referrals. Of 740 deliverable questionnaires, 503 were returned for a response rate of 68%. Less than 20% of chiropractors (18.8%) were aligned with a predefined unorthodox perspective of the conditions they treat. Prediction models suggest that unorthodox perceptions of health practice related to treatment choices, x-ray use and vaccinations were strongly associated with unorthodox group membership (X(2) =13.4, p = 0.0002). Chiropractors holding unorthodox views may be identified based on response to specific beliefs that appear to align with unorthodox health practices. Despite continued concerns by mainstream medicine, only a minority of the profession has retained a perspective in contrast to current scientific paradigms. Understanding the profession's factions is important to the anticipation of care delivery when considering interprofessional referral.

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

    PubMed Central

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

    2017-01-01

    Most real-world networks are too large to be measured or studied directly and there is substantial interest in estimating global network properties from smaller sub-samples. One of the most important global properties is the number of vertices/nodes in the network. Estimating the number of vertices in a large network is a major challenge in computer science, epidemiology, demography, and intelligence analysis. In this paper we consider a population random graph G = (V, E) from the stochastic block model (SBM) with K communities/blocks. A sample is obtained by randomly choosing a subset W ⊆ V and letting G(W) be the induced subgraph in G of the vertices in W. In addition to G(W), we observe the total degree of each sampled vertex and its block membership. Given this partial information, we propose an efficient PopULation Size Estimation algorithm, called PULSE, that accurately estimates the size of the whole population as well as the size of each community. To support our theoretical analysis, we perform an exhaustive set of experiments to study the effects of sample size, K, and SBM model parameters on the accuracy of the estimates. The experimental results also demonstrate that PULSE significantly outperforms a widely-used method called the network scale-up estimator in a wide variety of scenarios. PMID:28867924

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

    PubMed

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

    2016-01-01

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

  17. Randomized clinical trial: pharmacokinetics and safety of multimatrix mesalamine for treatment of pediatric ulcerative colitis

    PubMed Central

    Cuffari, Carmen; Pierce, David; Korczowski, Bartosz; Fyderek, Krzysztof; Van Heusen, Heather; Hossack, Stuart; Wan, Hong; Edwards, Alena YZ; Martin, Patrick

    2016-01-01

    Background Limited data are available on mesalamine (5-aminosalicylic acid; 5-ASA) use in pediatric ulcerative colitis (UC). Aim To evaluate pharmacokinetic and safety profiles of 5-ASA and metabolite acetyl-5-ASA (Ac-5-ASA) after once-daily, oral administration of multimatrix mesalamine to children and adolescents with UC. Methods Participants (5–17 years of age; 18–82 kg, stratified by weight) with UC received multi-matrix mesalamine 30, 60, or 100 mg/kg/day once daily (to 4,800 mg/day) for 7 days. Blood samples were collected pre-dose on days 5 and 6. On days 7 and 8, blood and urine samples were collected and safety was evaluated. 5-ASA and Ac-5-ASA plasma and urine concentrations were analyzed by non-compartmental methods and used to develop a population pharmacokinetic model. Results Fifty-two subjects (21 [30 mg/kg]; 22 [60 mg/kg]; 9 [100 mg/kg]) were randomized. On day 7, systemic exposures of 5-ASA and Ac-5-ASA exhibited a dose-proportional increase between 30 and 60 mg/kg/day cohorts. For 30, 60, and 100 mg/kg/day doses, mean percentages of 5-ASA absorbed were 29.4%, 27.0%, and 22.1%, respectively. Simulated steady-state exposures and variabilities for 5-ASA and Ac-5-ASA (coefficient of variation approximately 50% and 40%–45%, respectively) were similar to those observed previously in adults at comparable doses. Treatment-emergent adverse events were reported by ten subjects. Events were similar among different doses and age groups with no new safety signals identified. Conclusion Children and adolescents with UC receiving multimatrix mesalamine demonstrated 5-ASA and Ac-5-ASA pharmacokinetic profiles similar to historical adult data. Multimatrix mesalamine was well tolerated across all dose and age groups. ClinicalTrials.gov Identifier: NCT01130844. PMID:26893546

  18. Randomized clinical trial: pharmacokinetics and safety of multimatrix mesalamine for treatment of pediatric ulcerative colitis.

    PubMed

    Cuffari, Carmen; Pierce, David; Korczowski, Bartosz; Fyderek, Krzysztof; Van Heusen, Heather; Hossack, Stuart; Wan, Hong; Edwards, Alena Y Z; Martin, Patrick

    2016-01-01

    Limited data are available on mesalamine (5-aminosalicylic acid; 5-ASA) use in pediatric ulcerative colitis (UC). To evaluate pharmacokinetic and safety profiles of 5-ASA and metabolite acetyl-5-ASA (Ac-5-ASA) after once-daily, oral administration of multimatrix mesalamine to children and adolescents with UC. Participants (5-17 years of age; 18-82 kg, stratified by weight) with UC received multi-matrix mesalamine 30, 60, or 100 mg/kg/day once daily (to 4,800 mg/day) for 7 days. Blood samples were collected pre-dose on days 5 and 6. On days 7 and 8, blood and urine samples were collected and safety was evaluated. 5-ASA and Ac-5-ASA plasma and urine concentrations were analyzed by non-compartmental methods and used to develop a population pharmacokinetic model. Fifty-two subjects (21 [30 mg/kg]; 22 [60 mg/kg]; 9 [100 mg/kg]) were randomized. On day 7, systemic exposures of 5-ASA and Ac-5-ASA exhibited a dose-proportional increase between 30 and 60 mg/kg/day cohorts. For 30, 60, and 100 mg/kg/day doses, mean percentages of 5-ASA absorbed were 29.4%, 27.0%, and 22.1%, respectively. Simulated steady-state exposures and variabilities for 5-ASA and Ac-5-ASA (coefficient of variation approximately 50% and 40%-45%, respectively) were similar to those observed previously in adults at comparable doses. Treatment-emergent adverse events were reported by ten subjects. Events were similar among different doses and age groups with no new safety signals identified. Children and adolescents with UC receiving multimatrix mesalamine demonstrated 5-ASA and Ac-5-ASA pharmacokinetic profiles similar to historical adult data. Multimatrix mesalamine was well tolerated across all dose and age groups. ClinicalTrials.gov Identifier: NCT01130844.

  19. Age-Related Corresponding Relationships of Controlled Force Exertion Measured by a Computer-Generated Sinusoidal and Quasi-Random Display

    ERIC Educational Resources Information Center

    Nagasawa, Yoshinori; Demura, Shinichi

    2011-01-01

    This study examined age-group corresponding relationships of the controlled force exertion based on sinusoidal and quasi-random waveforms in 175 right-handed male adults aged 20 to 86 years. The subjects were divided into 3 groups based on age-level: 53 young (mean age 24.6, SD = 3.3 years), 71 middle aged (mean age 44.3, SD = 8.7 years), and 51…

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

    NASA Technical Reports Server (NTRS)

    Sree, David

    1992-01-01

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

  1. Identification of Domestic Violence Service Needs Among Child Welfare-Involved Parents With Substance Use Disorders: A Gender-Stratified Analysis.

    PubMed

    Victor, Bryan G; Resko, Stella M; Ryan, Joseph P; Perron, Brian E

    2018-04-01

    The current study examined the prevalence and associations of a need for domestic violence services among child welfare-involved mothers and fathers with substance use disorders. Data were drawn from 2,231 child welfare-involved parents in Illinois with an identified substance use disorder. Approximately 42% of mothers and 33% of fathers with a substance use disorder had a concurrent need for domestic violence services. The sample was stratified by gender and logistic regression models were fit to determine the adjusted odds of an identified need for domestic violence services. For both mothers and fathers, the strongest association was an additional need for mental health services. Age, education status, alcohol use, marijuana use, and a reported history of physical violence victimization were also associated with a need for domestic violence services among mothers, while race, age, marital status, annual income, alcohol use, cocaine use, and a reported history of physical violence perpetration were associated with a need for domestic violence services among fathers. The findings of this study make clear that domestic violence is a commonly co-occurring service need for child welfare-involved parents with identified substance use disorders, and that associations with this need vary by gender.

  2. Sampling High-Altitude and Stratified Mating Flights of Red Imported Fire Ant

    USDA-ARS?s Scientific Manuscript database

    With the exception of an airplane equipped with nets, no method has been developed that successfully samples red imported fire ant, Solenopsis invicta Buren, sexuals in mating/dispersal flights throughout their potential altitudinal trajectories. We developed and tested a method for sampling queens ...

  3. Comparison of Sampling Designs for Estimating Deforestation from Landsat TM and MODIS Imagery: A Case Study in Mato Grosso, Brazil

    PubMed Central

    Zhu, Shanyou; Zhang, Hailong; Liu, Ronggao; Cao, Yun; Zhang, Guixin

    2014-01-01

    Sampling designs are commonly used to estimate deforestation over large areas, but comparisons between different sampling strategies are required. Using PRODES deforestation data as a reference, deforestation in the state of Mato Grosso in Brazil from 2005 to 2006 is evaluated using Landsat imagery and a nearly synchronous MODIS dataset. The MODIS-derived deforestation is used to assist in sampling and extrapolation. Three sampling designs are compared according to the estimated deforestation of the entire study area based on simple extrapolation and linear regression models. The results show that stratified sampling for strata construction and sample allocation using the MODIS-derived deforestation hotspots provided more precise estimations than simple random and systematic sampling. Moreover, the relationship between the MODIS-derived and TM-derived deforestation provides a precise estimate of the total deforestation area as well as the distribution of deforestation in each block. PMID:25258742

  4. A Systematic Review of Surgical Randomized Controlled Trials: Part 2. Funding Source, Conflict of Interest, and Sample Size in Plastic Surgery.

    PubMed

    Voineskos, Sophocles H; Coroneos, Christopher J; Ziolkowski, Natalia I; Kaur, Manraj N; Banfield, Laura; Meade, Maureen O; Chung, Kevin C; Thoma, Achilleas; Bhandari, Mohit

    2016-02-01

    The authors examined industry support, conflict of interest, and sample size in plastic surgery randomized controlled trials that compared surgical interventions. They hypothesized that industry-funded trials demonstrate statistically significant outcomes more often, and randomized controlled trials with small sample sizes report statistically significant results more frequently. An electronic search identified randomized controlled trials published between 2000 and 2013. Independent reviewers assessed manuscripts and performed data extraction. Funding source, conflict of interest, primary outcome direction, and sample size were examined. Chi-squared and independent-samples t tests were used in the analysis. The search identified 173 randomized controlled trials, of which 100 (58 percent) did not acknowledge funding status. A relationship between funding source and trial outcome direction was not observed. Both funding status and conflict of interest reporting improved over time. Only 24 percent (six of 25) of industry-funded randomized controlled trials reported authors to have independent control of data and manuscript contents. The mean number of patients randomized was 73 per trial (median, 43, minimum, 3, maximum, 936). Small trials were not found to be positive more often than large trials (p = 0.87). Randomized controlled trials with small sample size were common; however, this provides great opportunity for the field to engage in further collaboration and produce larger, more definitive trials. Reporting of trial funding and conflict of interest is historically poor, but it greatly improved over the study period. Underreporting at author and journal levels remains a limitation when assessing the relationship between funding source and trial outcomes. Improved reporting and manuscript control should be goals that both authors and journals can actively achieve.

  5. Distributed fiber sparse-wideband vibration sensing by sub-Nyquist additive random sampling

    NASA Astrophysics Data System (ADS)

    Zhang, Jingdong; Zheng, Hua; Zhu, Tao; Yin, Guolu; Liu, Min; Bai, Yongzhong; Qu, Dingrong; Qiu, Feng; Huang, Xianbing

    2018-05-01

    The round trip time of the light pulse limits the maximum detectable vibration frequency response range of phase-sensitive optical time domain reflectometry ({\\phi}-OTDR). Unlike the uniform laser pulse interval in conventional {\\phi}-OTDR, we randomly modulate the pulse interval, so that an equivalent sub-Nyquist additive random sampling (sNARS) is realized for every sensing point of the long interrogation fiber. For an {\\phi}-OTDR system with 10 km sensing length, the sNARS method is optimized by theoretical analysis and Monte Carlo simulation, and the experimental results verify that a wide-band spars signal can be identified and reconstructed. Such a method can broaden the vibration frequency response range of {\\phi}-OTDR, which is of great significance in sparse-wideband-frequency vibration signal detection, such as rail track monitoring and metal defect detection.

  6. Soil mixing of stratified contaminated sands.

    PubMed

    Al-Tabba, A; Ayotamuno, M J; Martin, R J

    2000-02-01

    Validation of soil mixing for the treatment of contaminated ground is needed in a wide range of site conditions to widen the application of the technology and to understand the mechanisms involved. Since very limited work has been carried out in heterogeneous ground conditions, this paper investigates the effectiveness of soil mixing in stratified sands using laboratory-scale augers. This enabled a low cost investigation of factors such as grout type and form, auger design, installation procedure, mixing mode, curing period, thickness of soil layers and natural moisture content on the unconfined compressive strength, leachability and leachate pH of the soil-grout mixes. The results showed that the auger design plays a very important part in the mixing process in heterogeneous sands. The variability of the properties measured in the stratified soils and the measurable variations caused by the various factors considered, highlighted the importance of duplicating appropriate in situ conditions, the usefulness of laboratory-scale modelling of in situ conditions and the importance of modelling soil and contaminant heterogeneities at the treatability study stage.

  7. Emissions from diesel and stratified charge powered cars. Final report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Springer, K.J.

    A total of ten passenger cars, four powered by diesel engines, two by stratified charge gasoline engines, one by a stratified charge operating on gasoline and diesel fuel, two by control equipped conventional engines, and one powered by a gas turbine, have been subjected to a wide variety of emissions evaluations. The vehicles, all late model, low mileage, included a Nissan Datsun, a Mercedes 220D, a Peugeot 504D, an Opel Rekord 2100D, a standard Capri, a stratified charge (PROCO) Capri, a low emission prototype Ford LTD, the Texaco TCCS stratified charge powered Cricket operated on gasoline and on diesel fuel,more » a Honda CVCC stratified charge, and a Chrysler gas turbine car. All were 4-cylinder except the LTD and the gas turbine. Tailpipe emissions were measured by the 1975 light duty Federal Test Procedure for gaseous emissions. Smoke and fuel economy were also determined during this test cycle. Chassis dynamometer versions of the 1974 heavy duty diesel smoke and gaseous emissions tests were employed. Odor and related instrumental-chemical measurements were made under seven steady state and three acceleration conditions. The prototype diesel odor analytical system, developed under CRC contract, was applied to the exhaust from both diesel and gasoline engines. Its use as a predictive method of diesel odor was investigated. Noise measurements were taken by SAE driveby as well as under a variety of exterior-interior conditions. Comparisons of the results for all vehicles are by emission category. The emissions from the group of diesel cars are compared to the conventional gasoline, Ford PROCO, Texas TCCS, and Honda CVCC.« less

  8. Stratified charge rotary aircraft engine technology enablement program

    NASA Technical Reports Server (NTRS)

    Badgley, P. R.; Irion, C. E.; Myers, D. M.

    1985-01-01

    The multifuel stratified charge rotary engine is discussed. A single rotor, 0.7L/40 cu in displacement, research rig engine was tested. The research rig engine was designed for operation at high speeds and pressures, combustion chamber peak pressure providing margin for speed and load excursions above the design requirement for a high is advanced aircraft engine. It is indicated that the single rotor research rig engine is capable of meeting the established design requirements of 120 kW, 8,000 RPM, 1,379 KPA BMEP. The research rig engine, when fully developed, will be a valuable tool for investigating, advanced and highly advanced technology components, and provide an understanding of the stratified charge rotary engine combustion process.

  9. Numerical simulation of stratified flows from laboratory experiments to coastal ocean

    NASA Astrophysics Data System (ADS)

    Fraunie, Philippe

    2014-05-01

    Numeric modeling of a flow past vertical strip uniformly towing with permanent velocity in horizontal direction in a linearly stratified talk which was based on a finite differences solver adapted to the low Reynolds Navier-Stokes equation with transport equation for salinity (LES simulation [6]) has demonstrated reasonable agreement with data of schlieren visualization, density marker and probe measurements of internal wave fields. Another approach based on two different numerical methods for one specific case of stably stratified incompressible flow was developed, using the compact finite-difference discretizations. The numerical scheme itself follows the principle of semi-discretisation, with high order compact discretisation in space, while the time integration is carried out by the Strong Stability Preserving Runge-Kutta scheme. Results were compared against the reference solution obtained by the AUSM finite volume method [7]. The test case allowed demonstrating the ability of selected numerical methods to represent stably stratified flows over horizontal strip [4] and hill type 2D obstacles [1, 3] with generation of internal waves. From previous LES [4] and RANS [8] realistic simulations code, the ability of research codes to reproduce field observations is discussed. ACKNOWLEDGMENTS This research work was supported by Region Provence Alpes Côte d'Azur - Modtercom project, the Research Plan MSM 6840770010 of the Ministry of education of Czech Republic and the Russian Foundation for Basic Research (grant 12-01-00128). REFERENCES 1. Chashechkin Yu.D., Mitkin V.V. Experimental study of a fine structure of 2D wakes and mixing past an obstacle in a continuously stratified fluid // Dynamics of Atmosphere and Oceans. 2001. V. 34. P. 165-187. 2. Chashechkin, Yu. D. Hydrodynamics of a sphere in a stratified fluid // Fluid Dyn. 1989. V.24(1) P. 1-7. 3. Mitkin V. V., Chashechkin Yu. D. Transformation of hanging discontinuities into vortex systems in a stratified flow

  10. A Tale of Two “Forests”: Random Forest Machine Learning Aids Tropical Forest Carbon Mapping

    PubMed Central

    Mascaro, Joseph; Asner, Gregory P.; Knapp, David E.; Kennedy-Bowdoin, Ty; Martin, Roberta E.; Anderson, Christopher; Higgins, Mark; Chadwick, K. Dana

    2014-01-01

    Accurate and spatially-explicit maps of tropical forest carbon stocks are needed to implement carbon offset mechanisms such as REDD+ (Reduced Deforestation and Degradation Plus). The Random Forest machine learning algorithm may aid carbon mapping applications using remotely-sensed data. However, Random Forest has never been compared to traditional and potentially more reliable techniques such as regionally stratified sampling and upscaling, and it has rarely been employed with spatial data. Here, we evaluated the performance of Random Forest in upscaling airborne LiDAR (Light Detection and Ranging)-based carbon estimates compared to the stratification approach over a 16-million hectare focal area of the Western Amazon. We considered two runs of Random Forest, both with and without spatial contextual modeling by including—in the latter case—x, and y position directly in the model. In each case, we set aside 8 million hectares (i.e., half of the focal area) for validation; this rigorous test of Random Forest went above and beyond the internal validation normally compiled by the algorithm (i.e., called “out-of-bag”), which proved insufficient for this spatial application. In this heterogeneous region of Northern Peru, the model with spatial context was the best preforming run of Random Forest, and explained 59% of LiDAR-based carbon estimates within the validation area, compared to 37% for stratification or 43% by Random Forest without spatial context. With the 60% improvement in explained variation, RMSE against validation LiDAR samples improved from 33 to 26 Mg C ha−1 when using Random Forest with spatial context. Our results suggest that spatial context should be considered when using Random Forest, and that doing so may result in substantially improved carbon stock modeling for purposes of climate change mitigation. PMID:24489686

  11. A Clinical Prediction Algorithm to Stratify Pediatric Musculoskeletal Infection by Severity

    PubMed Central

    Benvenuti, Michael A; An, Thomas J; Mignemi, Megan E; Martus, Jeffrey E; Mencio, Gregory A; Lovejoy, Stephen A; Thomsen, Isaac P; Schoenecker, Jonathan G; Williams, Derek J

    2016-01-01

    Objective There are currently no algorithms for early stratification of pediatric musculoskeletal infection (MSKI) severity that are applicable to all types of tissue involvement. In this study, the authors sought to develop a clinical prediction algorithm that accurately stratifies infection severity based on clinical and laboratory data at presentation to the emergency department. Methods An IRB-approved retrospective review was conducted to identify patients aged 0–18 who presented to the pediatric emergency department at a tertiary care children’s hospital with concern for acute MSKI over a five-year period (2008–2013). Qualifying records were reviewed to obtain clinical and laboratory data and to classify in-hospital outcomes using a three-tiered severity stratification system. Ordinal regression was used to estimate risk for each outcome. Candidate predictors included age, temperature, respiratory rate, heart rate, C-reactive protein, and peripheral white blood cell count. We fit fully specified (all predictors) and reduced models (retaining predictors with a p-value ≤ 0.2). Discriminatory power of the models was assessed using the concordance (c)-index. Results Of the 273 identified children, 191 (70%) met inclusion criteria. Median age was 5.8 years. Outcomes included 47 (25%) children with inflammation only, 41 (21%) with local infection, and 103 (54%) with disseminated infection. Both the full and reduced models accurately demonstrated excellent performance (full model c-index 0.83, 95% CI [0.79–0.88]; reduced model 0.83, 95% CI [0.78–0.87]). Model fit was also similar, indicating preference for the reduced model. Variables in this model included C-reactive protein, pulse, temperature, and an interaction term for pulse and temperature. The odds of a more severe outcome increased by 30% for every 10-unit increase in C-reactive protein. Conclusions Clinical and laboratory data obtained in the emergency department may be used to accurately

  12. [The prevalence of obstructive sleep apnea-hypopnea syndrome in adults aged over 20 years in Changchun city].

    PubMed

    Li, Ming-xian; Wang, Ying; Hua, Shu-cheng; Li, Chun-mei; Wang, Mu-peng; Liu, Yang; Li, Zhong-min; Wang, Chun-yong; Fan, Jin-rong; Wang, Jing-Hua; Kong, Fan-yu; Wang, Min

    2005-12-01

    To investigate the prevalence of obstructive sleep apnea-hypopnea syndrome (OSAHS) in adults aged over 20 years in Changchun city, providing epidemiological data for treatment and prevention of the disease. 3,960 subjects were derived from a stratified cluster and random sampling of the population in two districts of Changchun city. They were asked to answer the questions from a questionnaire in their houses. According to the degree of snoring, 200 subjects with a snoring score >or= 2 degree were selected to undergo polysomnography for a whole night and the prevalence of the disease was estimated. A total of 3,648 (97.64%) validated questionnaires was collected. Of them 31.00% had a snoring score >or= 2 degree, the prevalence was higher in males (40.07%) than in females (21.76%). The prevalence of snoring was higher in drivers (42.47%) than in other occupations. The estimated prevalence of OSAHS defined by apnea-hypopnea index (AHI) >or= 5, Epworth sleepiness scale (ESS) >or= 9 and arterial oxygen saturation (SaO(2)) < 90% was 4.81%. The estimated prevalence of OSAHS in adults aged over 20 years in Changchun city was 4.81%. Doctors should pay more attention to the disease and the ordinary people should be informed of the health impact of snoring and OSAHS.

  13. Neurocognitive effects of neurofeedback in adolescents with ADHD: a randomized controlled trial.

    PubMed

    Bink, Marleen; van Nieuwenhuizen, Chijs; Popma, Arne; Bongers, Ilja L; van Boxtel, Geert J M

    2014-05-01

    Neurofeedback aims to reduce symptoms of attention-deficit/hyperactivity disorder (ADHD), mainly attention problems. However, the additional influence of neurofeedback over treatment as usual (TAU) on neurocognitive functioning for adolescents with ADHD remains unclear. By using a multicenter parallel randomized controlled trial (RCT) design, male adolescents with a DSM-IV-TR diagnosis of ADHD (mean age = 16.1 years; range, 12-24) were randomized to receive either a combination of TAU and neurofeedback (n = 45) or TAU (n = 26). Randomization was computer generated and stratified by age group (ages 12 through 15, 16 through 20, and 21 through 24 years). The neurofeedback intervention consisted of approximately 37 sessions over a period of 25 weeks of theta/sensorimotor rhythm training on the vertex (Cz). Primary neurocognitive outcomes included performance parameters derived from the D2 Test of Attention, the Digit Span backward, the Stroop Color-Word Test and the Tower of London, all assessed preintervention and postintervention. Data were collected between December 2009 and July 2012. At postintervention, outcomes of attention and/or motor speed were improved, with faster processing times for both intervention conditions and with medium to large effect sizes (range, ηp2 = .08-.54; P values < .023). In both groups, no improvements for higher executive functions were observed. Results might partly resemble practice effects. Although neurocognitive outcomes improved in all adolescents receiving treatment for ADHD, no additional value for neurofeedback over TAU was observed. Hence, this study does not provide evidence for using theta/sensorimotor rhythm neurofeedback to enhance neurocognitive performance as additional intervention to TAU for adolescents with ADHD symptoms. Trialregister.nl identifier: 1759. © Copyright 2014 Physicians Postgraduate Press, Inc.

  14. Exploring comfort food preferences across age and gender.

    PubMed

    Wansink, Brian; Cheney, Matthew M; Chan, Nina

    2003-09-01

    Building on findings related to physiological and psychological motivations of food preference, this research develops a framework to examine preferences toward comfort foods. Study 1 used a North American survey of 411 people to determine favored comfort foods, and Study 2 quantified the preferences for these foods across gender and across age groups using a stratified sample of 1005 additional people. Consistent with hypotheses, the findings showed different comfort food preferences across gender and across age. Males preferred warm, hearty, meal-related comfort foods (such as steak, casseroles, and soup), while females instead preferred comfort foods that were more snack related (such as chocolate and ice cream). In addition, younger people preferred more snack-related comfort foods compared to those over 55 years of age. Associations with guilty feelings underscored how these different preferences between males and females may extend to areas of application.

  15. Stratified vapor generator

    DOEpatents

    Bharathan, Desikan [Lakewood, CO; Hassani, Vahab [Golden, CO

    2008-05-20

    A stratified vapor generator (110) comprises a first heating section (H.sub.1) and a second heating section (H.sub.2). The first and second heating sections (H.sub.1, H.sub.2) are arranged so that the inlet of the second heating section (H.sub.2) is operatively associated with the outlet of the first heating section (H.sub.1). A moisture separator (126) having a vapor outlet (164) and a liquid outlet (144) is operatively associated with the outlet (124) of the second heating section (H.sub.2). A cooling section (C.sub.1) is operatively associated with the liquid outlet (144) of the moisture separator (126) and includes an outlet that is operatively associated with the inlet of the second heating section (H.sub.2).

  16. Exercise training improves exercise capacity in adult patients with a systemic right ventricle: a randomized clinical trial.

    PubMed

    Winter, Michiel M; van der Bom, Teun; de Vries, Leonie C S; Balducci, Anna; Bouma, Berto J; Pieper, Petronella G; van Dijk, Arie P J; van der Plas, Mart N; Picchio, Fernando M; Mulder, Barbara J M

    2012-06-01

    To assess whether exercise training in adult patients with a systemic right ventricle (RV) improves exercise capacity and quality of life and lowers serum N-terminal prohormone brain natriuretic peptide (NT-proBNP) levels. Multi-centre parallel randomized controlled trial. Patients with a systemic RV due to congenitally or surgically corrected transposition of the great arteries. Fifty-four adult patients with a systemic RV, were randomized using unmarked opaque envelopes to an intervention group (n = 28) with three training sessions per week for 10 consecutive weeks, and a control group (n = 26). Randomization was stratified by participating centre. At baseline, and follow-up, we determined maximal exercise capacity (V'O(2peak)), serum NT-proBNP levels, and quality of life by means of the SF-36, and the TAAQOL Congenital Heart Disease questionnaires. The final analysis was performed by linear regression, taking into account the stratified randomization. Forty-six patients were analysed (male 50%, age 32 ± 11 years, intervention group n = 24, control group n = 22). Analysis at 10 weeks showed a significant difference in V'O(2peak) (3.4 mL/kg/min, 95% CI: 0.2 to 6.7; P = 0.04) and resting systolic blood pressure (-7.6 mmHg, 95% CI: -14.0 to -1.3; P = 0.03) in favour of the exercise group. No significant changes were found in serum NT-proBNP levels or quality of life in the intervention group or in the control group nor between groups. None of the patients in the intervention group had to discontinue the training programme due to adverse events. In adult patients with a systemic RV exercise training improve exercise capacity. We recommend to revise restrictive guidelines, and to encourage patients to become physically active. ( The study was registered at http://trialregister.nl. Identifier: NTR1909.).

  17. Advanced ovarian cancer: phase III randomized study of sequential cisplatin-topotecan and carboplatin-paclitaxel vs carboplatin-paclitaxel.

    PubMed

    Hoskins, P; Vergote, I; Cervantes, A; Tu, D; Stuart, G; Zola, P; Poveda, A; Provencher, D; Katsaros, D; Ojeda, B; Ghatage, P; Grimshaw, R; Casado, A; Elit, L; Mendiola, C; Sugimoto, A; D'Hondt, V; Oza, A; Germa, J R; Roy, M; Brotto, L; Chen, D; Eisenhauer, E A

    2010-10-20

    Topotecan has single-agent activity in recurrent ovarian cancer. It was evaluated in a novel combination compared with standard frontline therapy. Women aged 75 years or younger with newly diagnosed stage IIB or greater ovarian cancer, Eastern Cooperative Oncology Group Performance Status of 1 or less, were stratified by type of primary surgery and residual disease, treatment center, and age; then randomly assigned to one of the two 21-day intravenous regimens. Patients in arm 1 (n = 409) were administered four cycles of cisplatin 50 mg/m(2) on day 1 and topotecan 0.75 mg/m(2) on days 1-5, then four cycles of paclitaxel 175 mg/m(2) over 3 hours on day 1 followed by carboplatin (area under the curve = 5) on day 1. Patients in arm 2 (n = 410) were given paclitaxel plus carboplatin as in arm 1 for eight cycles. We compared progression-free survival (PFS), overall survival, and cancer antigen-125 normalization rates in the two treatment arms. A stratified log-rank test was used to assess the primary endpoint, PFS. All statistical tests were two-sided. A total of 819 patients were randomly assigned. At baseline, the median age of the patients was 57 years (range = 28-78); 81% had received debulking surgery, and of these, 55% had less than 1 cm residual disease; 66% of patients were stage III and 388 (47.4%) patients had measurable disease. After a median follow-up of 43 months, 650 patients had disease progression or died without documented progression and 406 had died. Patients in arm 1 had more hematological toxicity and hospitalizations than patients in arm 2; PFS was 14.6 months in arm 1 vs 16.2 months in arm 2 (hazard ratio = 1.10, 95% confidence interval = 0.94 to 1.28, P = .25). Among patients with elevated baseline cancer antigen-125, fewer in arm 1 than in arm 2 had levels return to normal by 3 months after random assignment (51.6% vs 63.3%, P = .007) Topotecan and cisplatin, followed by carboplatin and paclitaxel, were more toxic than carboplatin and

  18. Response of the Elderly to Disaster: An Age-Stratified Analysis.

    ERIC Educational Resources Information Center

    Bolin, Robert; Klenow, Daniel J.

    1982-01-01

    Analyzed the effect of age on elderly tornado victims' (N=62) responses to stress effects. Compared to younger victims (N=240), the elderly did not suffer disproportionate material losses, but were more likely to be injured and have a death in the household. Elderly victims had a lower incidene of emotional and family problems. (Author/JAC)

  19. Species conservation profiles of a random sample of world spiders I: Agelenidae to Filistatidae.

    PubMed

    Seppälä, Sini; Henriques, Sérgio; Draney, Michael L; Foord, Stefan; Gibbons, Alastair T; Gomez, Luz A; Kariko, Sarah; Malumbres-Olarte, Jagoba; Milne, Marc; Vink, Cor J; Cardoso, Pedro

    2018-01-01

    The IUCN Red List of Threatened Species is the most widely used information source on the extinction risk of species. One of the uses of the Red List is to evaluate and monitor the state of biodiversity and a possible approach for this purpose is the Red List Index (RLI). For many taxa, mainly hyperdiverse groups, it is not possible within available resources to assess all known species. In such cases, a random sample of species might be selected for assessment and the results derived from it extrapolated for the entire group - the Sampled Red List Index (SRLI). With the current contribution and the three following papers, we intend to create the first point in time of a future spider SRLI encompassing 200 species distributed across the world. A sample of 200 species of spiders were randomly selected from the World Spider Catalogue, an updated global database containing all recognised species names for the group. The 200 selected species where divided taxonomically at the family level and the familes were ordered alphabetically. In this publication, we present the conservation profiles of 46 species belonging to the famillies alphabetically arranged between Agelenidae and Filistatidae, which encompassed Agelenidae, Amaurobiidae, Anyphaenidae, Araneidae, Archaeidae, Barychelidae, Clubionidae, Corinnidae, Ctenidae, Ctenizidae, Cyatholipidae, Dictynidae, Dysderidae, Eresidae and Filistatidae.

  20. Age-related Cataract in a Randomized Trial of Vitamins E and C in Men

    PubMed Central

    Christen, William G.; Glynn, Robert J.; Sesso, Howard D.; Kurth, Tobias; MacFadyen, Jean; Bubes, Vadim; Buring, Julie E.; Manson, JoAnn E.; Michael Gaziano, J.

    2010-01-01

    Objective To test whether supplementation with alternate day vitamin E or daily vitamin C affects the incidence of age-related cataract in a large-scale randomized trial of men. Design Randomized, double-masked, placebo-controlled trial. Participants Eleven thousand five hundred forty-five apparently healthy US male physicians aged 50 years or older who were without a diagnosis of cataract at baseline. Intervention Participants were randomly assigned to receive 400 IU of vitamin E or placebo on alternate days, and 500 mg of vitamin C or placebo daily. Main Outcome Measure Incident cataract responsible for a reduction in best-corrected visual acuity to 20/30 or worse based on self-report confirmed by medical record review. Results After 8 years of treatment and follow-up, a total of 1,174 incident cataracts were confirmed. There were 579 cataracts in the vitamin E treated group and 595 in the vitamin E placebo group (hazard ratio [HR], 0.99; 95 percent confidence interval [CI], 0.88 to 1.11). For vitamin C, there were 593 cataracts in the treated group and 581 in the placebo group (HR, 1.02; CI, 0.91 to 1.14). Conclusions In a large-scale randomized trial of US male physicians, long-term alternate day use of 400 IU of vitamin E and/or daily use of 500 mg of vitamin C had no significant beneficial or harmful effect on the risk of cataract. Application to Clinical Practice Long-term use of vitamin E and/or vitamin C supplements has no appreciable effect on cataract. PMID:21060040

  1. Assessing the Causal Relationship of Maternal Height on Birth Size and Gestational Age at Birth: A Mendelian Randomization Analysis

    PubMed Central

    Zhang, Ge; Bacelis, Jonas; Lengyel, Candice; Teramo, Kari; Hallman, Mikko; Helgeland, Øyvind; Johansson, Stefan; Myhre, Ronny; Sengpiel, Verena; Njølstad, Pål Rasmus; Jacobsson, Bo; Muglia, Louis

    2015-01-01

    height resulting in ~0.4 more gestational d. Limitations of this study include potential influences in causal inference by biological pleiotropy, assortative mating, and the nonrandom sampling of study subjects. Conclusions Our results demonstrate that the observed association between maternal height and fetal growth measures (i.e., birth length and birth weight) is mainly defined by fetal genetics. In contrast, the association between maternal height and gestational age is more likely to be causal. In addition, our approach that utilizes the genetic score derived from the nontransmitted maternal haplotype as a genetic instrument is a novel extension to the Mendelian randomization methodology in casual inference between parental phenotype (or exposure) and outcomes in offspring. PMID:26284790

  2. Stably stratified canopy flow in complex terrain

    NASA Astrophysics Data System (ADS)

    Xu, X.; Yi, C.; Kutter, E.

    2015-07-01

    Stably stratified canopy flow in complex terrain has been considered a difficult condition for measuring net ecosystem-atmosphere exchanges of carbon, water vapor, and energy. A long-standing advection error in eddy-flux measurements is caused by stably stratified canopy flow. Such a condition with strong thermal gradient and less turbulent air is also difficult for modeling. To understand the challenging atmospheric condition for eddy-flux measurements, we use the renormalized group (RNG) k-ϵ turbulence model to investigate the main characteristics of stably stratified canopy flows in complex terrain. In this two-dimensional simulation, we imposed persistent constant heat flux at ground surface and linearly increasing cooling rate in the upper-canopy layer, vertically varying dissipative force from canopy drag elements, buoyancy forcing induced from thermal stratification and the hill terrain. These strong boundary effects keep nonlinearity in the two-dimensional Navier-Stokes equations high enough to generate turbulent behavior. The fundamental characteristics of nighttime canopy flow over complex terrain measured by the small number of available multi-tower advection experiments can be reproduced by this numerical simulation, such as (1) unstable layer in the canopy and super-stable layers associated with flow decoupling in deep canopy and near the top of canopy; (2) sub-canopy drainage flow and drainage flow near the top of canopy in calm night; (3) upward momentum transfer in canopy, downward heat transfer in upper canopy and upward heat transfer in deep canopy; and (4) large buoyancy suppression and weak shear production in strong stability.

  3. ENHANCEMENT OF LEARNING ON SAMPLE SIZE CALCULATION WITH A SMARTPHONE APPLICATION: A CLUSTER-RANDOMIZED CONTROLLED TRIAL.

    PubMed

    Ngamjarus, Chetta; Chongsuvivatwong, Virasakdi; McNeil, Edward; Holling, Heinz

    2017-01-01

    Sample size determination usually is taught based on theory and is difficult to understand. Using a smartphone application to teach sample size calculation ought to be more attractive to students than using lectures only. This study compared levels of understanding of sample size calculations for research studies between participants attending a lecture only versus lecture combined with using a smartphone application to calculate sample sizes, to explore factors affecting level of post-test score after training sample size calculation, and to investigate participants’ attitude toward a sample size application. A cluster-randomized controlled trial involving a number of health institutes in Thailand was carried out from October 2014 to March 2015. A total of 673 professional participants were enrolled and randomly allocated to one of two groups, namely, 341 participants in 10 workshops to control group and 332 participants in 9 workshops to intervention group. Lectures on sample size calculation were given in the control group, while lectures using a smartphone application were supplied to the test group. Participants in the intervention group had better learning of sample size calculation (2.7 points out of maximnum 10 points, 95% CI: 24 - 2.9) than the participants in the control group (1.6 points, 95% CI: 1.4 - 1.8). Participants doing research projects had a higher post-test score than those who did not have a plan to conduct research projects (0.9 point, 95% CI: 0.5 - 1.4). The majority of the participants had a positive attitude towards the use of smartphone application for learning sample size calculation.

  4. Hydrogeology and water quality of the stratified-drift aquifer in the Pony Hollow Creek Valley, Tompkins County, New York

    USGS Publications Warehouse

    Bugliosi, Edward F.; Miller, Todd S.; Reynolds, Richard J.

    2014-01-01

    The lithology, areal extent, and the water-table configuration in stratified-drift aquifers in the northern part of the Pony Hollow Creek valley in the Town of Newfield, New York, were mapped as part of an ongoing aquifer mapping program in Tompkins County. Surficial geologic and soil maps, well and test-boring records, light detection and ranging (lidar) data, water-level measurements, and passive-seismic surveys were used to map the aquifer geometry, construct geologic sections, and determine the depth to bedrock at selected locations throughout the valley. Additionally, water-quality samples were collected from selected streams and wells to characterize the quality of surface and groundwater in the study area. Sedimentary bedrock underlies the study area and is overlain by unstratified drift (till), stratified drift (glaciolacustrine and glaciofluvial deposits), and recent post glacial alluvium. The major type of unconsolidated, water-yielding material in the study area is stratified drift, which consists of glaciofluvial sand and gravel, and is present in sufficient amounts in most places to form an extensive unconfined aquifer throughout the study area, which is the source of water for most residents, farms, and businesses in the valleys. A map of the water table in the unconfined aquifer was constructed by using (1) measurements made between the mid-1960s through 2010, (2) control on the altitudes of perennial streams at 10-foot contour intervals from lidar data collected by Tompkins County, and (3) water surfaces of ponds and wetlands that are hydraulically connected to the unconfined aquifer. Water-table contours indicate that the direction of groundwater flow within the stratified-drift aquifer is predominantly from the valley walls toward the streams and ponds in the central part of the valley where groundwater then flows southwestward (down valley) toward the confluence with the Cayuta Creek valley. Locally, the direction of groundwater flow is radially

  5. Randomized Controlled Trial of Therapeutic Horseback Riding in Children and Adolescents With Autism Spectrum Disorder.

    PubMed

    Gabriels, Robin L; Pan, Zhaoxing; Dechant, Briar; Agnew, John A; Brim, Natalie; Mesibov, Gary

    2015-07-01

    This study expands previous equine-assisted intervention research by evaluating the effectiveness of therapeutic horseback riding (THR) on self-regulation, socialization, communication, adaptive, and motor behaviors in children with autism spectrum disorder (ASD). Participants with ASD (aged 6-16 years; N = 127) were stratified by nonverbal IQ standard scores (≤85 or >85) and randomized to 1 of 2 groups for 10 weeks: THR intervention or a barn activity (BA) control group without horses that used similar methods. The fidelity of the THR intervention was monitored. Participants were evaluated within 1 month pre- and postintervention by raters blinded to intervention conditions and unblinded caregiver questionnaires. During the intervention, caregivers rated participants' behaviors weekly. Intent-to-treat analysis conducted on the 116 participants who completed a baseline assessment (THR n = 58; BA control n = 58) revealed significant improvements in the THR group compared to the control on measures of irritability (primary outcome) (p = .02; effect size [ES] = 0.50) and hyperactivity (p = .01; ES = 0.53), beginning by week 5 of the intervention. Significant improvements in the THR group were also observed on a measure of social cognition (p = .05; ES = 0.41) and social communication (p = .003; ES = 0.63), along with the total number of words (p = .01; ES = 0.54) and new words (p = .01; ES = 0.54) spoken during a standardized language sample. Sensitivity analyses adjusting for age, IQ, and per protocol analyses produced consistent results. This is the first large-scale, randomized, controlled trial demonstrating efficacy of THR for the ASD population, and findings are consistent with previous equine-assisted intervention studies. Trial of Therapeutic Horseback Riding in Children and Adolescents With Autism Spectrum Disorder; http://clinicaltrials.gov; NCT02301195. Published by Elsevier Inc.

  6. Age of Lunar Meteorite LAP02205 and Implications for Impact-Sampling of Planetary Surfaces

    NASA Technical Reports Server (NTRS)

    Nyquist, L. E.; Shih, C.-Y.; Reese, Y.; Bogard, D. D.

    2005-01-01

    We have measured the age of lunar meteorite LAP02205 by the Rb-Sr and Ar-Ar methods. Sm-Nd analyses are in progress. The Rb-Sr and Ar-Ar ages indicate a crystallization age of approx. 3 Ga. Comparing the ages of LAP02205 and other lunar mare basaltic meteorites to mare surface ages based on the density of impact craters shows no significant bias in impact- sampling of lunar mare surfaces. Comparing the isotopic and geochemical data for LAP02205 to those for other lunar mare basalts suggests that it is a younger variant of the type of volcanism that produced the Apollo 12 basalts. Representative impact-sampling of the lunar surface

  7. Psychosocial Distress in Bladder Cancer Stratified by Gender, Age, Treatment, and Tumour Stage.

    PubMed

    Draeger, Désirée Louise; Sievert, Karl-Dietrich; Hakenberg, Oliver W

    2018-05-14

    Cancer patients have to cope with anxieties -concerning their prognosis, potential recurrence/progression, and treatment-associated sequelae. Stress-related psychosocial factors influence survival and disease-related mortality in cancer patients. Despite improvements in diagnosis and treatment, bladder cancer (BC) remains characterized by high rates of recurrence and progression. We screened -pre-therapeutically the stress level of BC patients stratified by gender, disease state, treatment, and other factors by -self-administered validated questionnaires to integrate them into psychosocial support as needed. A cross-sectional analysis of distress and need of psychosocial care was done in 301 patients undergoing treatment for BC by 2 questionnaires (Distress Thermometer [DT] and Hornheider Screening Instrument). Of the 301 patients, 230 patients underwent transurethral resection for a first -diagnosis, 63 for recurrent disease, 37 had progressive disease, and 25 had advanced metastatic disease and eventually died of BC. The mean stress level in all patients was 4.6. Twenty-eight percent of the patients expressed a need for psychosocial support. In patients with progressive disease, significantly higher stress scores were seen as well as a higher need of psychosocial care (5.4 and 41%). The median DT-level of 4.6 indicates moderate psychosocial stress in BC patients. From a stress level of 5, the recommendations of a psycho-oncological supervision are pronounced, so that our study showed that early systematic evaluation of psychosocial needs in BC patients is important. © 2018 S. Karger AG, Basel.

  8. Modeling the Conducting Stably-Stratified Layer of the Earth's Core

    NASA Astrophysics Data System (ADS)

    Petitdemange, L.; Philidet, J.; Gissinger, C.

    2017-12-01

    Observations of the Earth magnetic field as well as recent theoretical works tend to show that the Earth's outer liquid core is mostly comprised of a convective zone in which the Earth's magnetic field is generated - likely by dynamo action -, but also features a thin, stably stratified layer at the top of the core.We carry out direct numerical simulations by modeling this thin layer as an axisymmetric spherical Couette flow for a stably stratified fluid embedded in a dipolar magnetic field. The dynamo region is modeled by a conducting inner core rotating slightly faster than the insulating mantle due to magnetic torques acting on it, such that a weak differential rotation (low Rossby limit) can develop in the stably stratified layer.In the case of a non-stratified fluid, the combined action of the differential rotation and the magnetic field leads to the well known regime of `super-rotation', in which the fluid rotates faster than the inner core. Whereas in the classical case, this super-rotation is known to vanish in the magnetostrophic limit, we show here that the fluid stratification significantly extends the magnitude of the super-rotation, keeping this phenomenon relevant for the Earth core. Finally, we study how the shear layers generated by this new state might give birth to magnetohydrodynamic instabilities or waves impacting the secular variations or jerks of the Earth's magnetic field.

  9. Convenience Samples and Caregiving Research: How Generalizable Are the Findings?

    ERIC Educational Resources Information Center

    Pruchno, Rachel A.; Brill, Jonathan E.; Shands, Yvonne; Gordon, Judith R.; Genderson, Maureen Wilson; Rose, Miriam; Cartwright, Francine

    2008-01-01

    Purpose: We contrast characteristics of respondents recruited using convenience strategies with those of respondents recruited by random digit dial (RDD) methods. We compare sample variances, means, and interrelationships among variables generated from the convenience and RDD samples. Design and Methods: Women aged 50 to 64 who work full time and…

  10. The relation between hypochondriasis and age.

    PubMed

    Barsky, A J; Frank, C B; Cleary, P D; Wyshak, G; Klerman, G L

    1991-07-01

    This study examined the relation between hypochondriasis and age while controlling for the possible confounding influences of medical morbidity, social isolation, and other psychiatric disorder. Consecutive patients attending a general medical clinic on randomly selected days were screened with a hypochondriasis self-report questionnaire. Those whose scores exceeded a preestablished cutoff level and a random sample of those who scored below it completed a research battery consisting of self-report questionnaires and structured interviews for DSM-III-R diagnoses of hypochondriasis and other axis I disorders. The patients' medical records were audited, and their physicians completed questionnaires about them. The 60 patients who met the DSM-III-R criteria for hypochondriasis at interview constituted the study group, and 100 patients randomly chosen from among those who scored below the cutoff for hypochondriasis constituted the comparison group. The hypochondriacal group was not older than the comparison group. Hypochondriacal patients aged 65 years and over did not differ significantly from younger hypochondriacal patients in hypochondriacal attitudes, somatization, tendency to amplify bodily sensation, or global assessment of their overall health, even though their aggregate medical morbidity was greater. The elderly hypochondriacal patients had higher levels of disability, but this appeared to be attributable to their medical status rather than to any increase in hypochondriasis. Within the comparison sample, subjects aged 65 years and over were not more hypochondriacal than those under 65 years of age. Hypochondriasis is found to some degree in all patients and appears to be unrelated to age.

  11. Urinary Arsenic in Human Samples from Areas Characterized by Natural or Anthropogenic Pollution in Italy.

    PubMed

    Minichilli, Fabrizio; Bianchi, Fabrizio; Ronchi, Anna Maria; Gorini, Francesca; Bustaffa, Elisa

    2018-02-09

    Arsenic is ubiquitous and has a potentially adverse impact on human health. We compared the distribution of concentrations of urinary inorganic arsenic plus methylated forms (uc(iAs+MMA+DMA)) in four Italian areas with other international studies, and we assessed the relationship between uc(iAs+MMA+DMA) and various exposure factors. We conducted a human biomonitoring study on 271 subjects (132 men) aged 20-44, randomly sampled and stratified by area, gender, and age. Data on environmental and occupational exposure and dietary habits were collected through a questionnaire. Arsenic was speciated using chromatographic separation and inductively coupled mass spectrometry. Associations between uc(iAs+MMA+DMA) and exposure factors were evaluated using the geometric mean ratio (GMR) with a 90% confidence interval by stepwise multiple regression analysis. The 95th percentile value of uc(iAs+MMA+DMA) for the whole sample (86.28 µg/L) was higher than other national studies worldwide. A statistical significant correlation was found between uc(iAs+MMA+DMA) and occupational exposure (GMR: 2.68 [1.79-4.00]), GSTT gene (GMR: 0.68 [0.52-0.80]), consumption of tap water (GMR: 1.35 [1.02-1.77]), seafood (GMR: 1.44 [1.11-1.88]), whole milk (GMR: 1.34 [1.04-1.73]), and fruit/vegetables (GMR: 1.37 [1.03-1.82]). This study demonstrated the utility of uc(iAs+MMA+DMA) as a biomarker to assess environmental exposure. In a public health context, this information could be used to support remedial action, to prevent individuals from being further exposed to environmental arsenic sources.

  12. Urinary Arsenic in Human Samples from Areas Characterized by Natural or Anthropogenic Pollution in Italy

    PubMed Central

    Minichilli, Fabrizio; Bianchi, Fabrizio; Ronchi, Anna Maria; Gorini, Francesca; Bustaffa, Elisa

    2018-01-01

    Arsenic is ubiquitous and has a potentially adverse impact on human health. We compared the distribution of concentrations of urinary inorganic arsenic plus methylated forms (uc(iAs+MMA+DMA)) in four Italian areas with other international studies, and we assessed the relationship between uc(iAs+MMA+DMA) and various exposure factors. We conducted a human biomonitoring study on 271 subjects (132 men) aged 20–44, randomly sampled and stratified by area, gender, and age. Data on environmental and occupational exposure and dietary habits were collected through a questionnaire. Arsenic was speciated using chromatographic separation and inductively coupled mass spectrometry. Associations between uc(iAs+MMA+DMA) and exposure factors were evaluated using the geometric mean ratio (GMR) with a 90% confidence interval by stepwise multiple regression analysis. The 95th percentile value of uc(iAs+MMA+DMA) for the whole sample (86.28 µg/L) was higher than other national studies worldwide. A statistical significant correlation was found between uc(iAs+MMA+DMA) and occupational exposure (GMR: 2.68 [1.79–4.00]), GSTT gene (GMR: 0.68 [0.52–0.80]), consumption of tap water (GMR: 1.35 [1.02–1.77]), seafood (GMR: 1.44 [1.11–1.88]), whole milk (GMR: 1.34 [1.04–1.73]), and fruit/vegetables (GMR: 1.37 [1.03–1.82]). This study demonstrated the utility of uc(iAs+MMA+DMA) as a biomarker to assess environmental exposure. In a public health context, this information could be used to support remedial action, to prevent individuals from being further exposed to environmental arsenic sources. PMID:29425136

  13. Optimum random and age replacement policies for customer-demand multi-state system reliability under imperfect maintenance

    NASA Astrophysics Data System (ADS)

    Chen, Yen-Luan; Chang, Chin-Chih; Sheu, Dwan-Fang

    2016-04-01

    This paper proposes the generalised random and age replacement policies for a multi-state system composed of multi-state elements. The degradation of the multi-state element is assumed to follow the non-homogeneous continuous time Markov process which is a continuous time and discrete state process. A recursive approach is presented to efficiently compute the time-dependent state probability distribution of the multi-state element. The state and performance distribution of the entire multi-state system is evaluated via the combination of the stochastic process and the Lz-transform method. The concept of customer-centred reliability measure is developed based on the system performance and the customer demand. We develop the random and age replacement policies for an aging multi-state system subject to imperfect maintenance in a failure (or unacceptable) state. For each policy, the optimum replacement schedule which minimises the mean cost rate is derived analytically and discussed numerically.

  14. Knowledge for unintentional injury and risky behavior among the school-age children in Changsha city of China.

    PubMed

    Tian, Lingyun; Liu, Minhui; Li, Li; Fang, Zhengqing; Xiao, Hongling; Wu, Ying; Xia, Yanping

    2016-07-01

    To investigate the current status on knowledge for unintentional injury and risky behavior among school-age children in Changsha, China, and to provide scientific evidence for the preventive strategies.
 A cross-sectional study was conducted on 866 students who were between 6 and 12 years old in Changsha. Two primary schools were selected by stratified cluster random sampling from all primary schools of Changsha city to collect the information regarding knowledge for unintentional injury and risky behavior occurring in the 6-month period before the survey.
 The mean score for knowledge of unintentional injury was 11.83±2.38. The levels of knowledge for unintentional injury differed significantly in child's age, parents' education background and child's injury history (P<0.05). The child's knowledge level was correlated with child's age, mother's education, child's injury history. The mean score for risky behavior was 17.61±10.35. The levels of risky behavior differed significantly in child's gender, father's age to have the child, parents' marriage status, whom does/do child live with, child's injury history and medical history since the birthday (P<0.05). There was a linear regression relationship between risky behavior and child's injury history, parents' marriage status, child's gender. There was no significant correlation between knowledge and risky behavior (P>0.05).
 It is a common phenomenon in school-age children who are lack of the knowledge for unintentional injury and risky behavior. This study provides useful information on the risk factors for unintentional injury and risky behavior, which would be significant for prevention program.

  15. [Urinary iodine levels and its influencing factors among residents over age of 15 years in Shenzhen City].

    PubMed

    Luo, Yiqi; Xu, Jian; He, Shan; Wang, Jun; Fang, Xiaoheng

    2014-11-01

    To understand the status of iodine nutrition and the affective factors of urinary iodine concentration among residents over age of 15 years in Shenzhen City. Totally 8152 residents from 73 communities were selected with stratified cluster random sampling. The morning urinary iodine was determined and the dietary assessment of iodine using a food frequency questionnaire were carried out. The range of urinary iodine was 9. 65 - 4039.09 μg/L and the median of urinary iodine was 194.59 μg/L among the residents. The percentages of the residents with urinary iodine < 50,50 - 100,100 - 199, 200 - 300, and ≥ 300 μg/L were 2.49%, 12.12%, 40.16%, 26.94% and 20.78%, respectively. There was significant difference in the medians of iodine between different gender (P = 0.0001), the medians of urinary iodine of men (201.32 μg/L) was slightly higher. There was no significant difference in urinary iodine levels (186.59 - 197.44 μg/L) among all age groups, the medians of urinary iodine of all age groups were within the recommended adequate intake. Along with the increase in age, the medians of urinary iodine of all age groups was gradually decreased. Sex, alcohol consumption and daily dietary iodine intake was significant in the final regression model. The iodine nutrition of residents in Shenzhen City was in good condition, populations with low or high iodine still exist. The monitoring is needed and the influencing factors of the urine iodine levels need much exploration.

  16. Influence of Psychosocial Factors on Aging among the Aged in Ihitte-Uboma Local Government Area of Imo State, Nigeria

    ERIC Educational Resources Information Center

    Ojukwu, M. O.

    2016-01-01

    The major aim of this study was to examine influence of psychosocial factors on aging among the aged in Ihitte Uboma Local Government Area of Imo State, Nigeria. Ex-post facto or casual comparative research design was adopted for the study. Two hundred and twenty-five (225) old people were selected through random sampling for the study.…

  17. Background stratified Poisson regression analysis of cohort data.

    PubMed

    Richardson, David B; Langholz, Bryan

    2012-03-01

    Background stratified Poisson regression is an approach that has been used in the analysis of data derived from a variety of epidemiologically important studies of radiation-exposed populations, including uranium miners, nuclear industry workers, and atomic bomb survivors. We describe a novel approach to fit Poisson regression models that adjust for a set of covariates through background stratification while directly estimating the radiation-disease association of primary interest. The approach makes use of an expression for the Poisson likelihood that treats the coefficients for stratum-specific indicator variables as 'nuisance' variables and avoids the need to explicitly estimate the coefficients for these stratum-specific parameters. Log-linear models, as well as other general relative rate models, are accommodated. This approach is illustrated using data from the Life Span Study of Japanese atomic bomb survivors and data from a study of underground uranium miners. The point estimate and confidence interval obtained from this 'conditional' regression approach are identical to the values obtained using unconditional Poisson regression with model terms for each background stratum. Moreover, it is shown that the proposed approach allows estimation of background stratified Poisson regression models of non-standard form, such as models that parameterize latency effects, as well as regression models in which the number of strata is large, thereby overcoming the limitations of previously available statistical software for fitting background stratified Poisson regression models.

  18. A Randomized Controlled Trial of Two Syntactic Treatment Procedures with Cantonese-Speaking, School-Age Children with Language Disorders

    ERIC Educational Resources Information Center

    To, Carol K. S.; Lui, Hoi Ming; Li, Xin Xin; Lam, Gary Y. H

    2015-01-01

    Purpose: In this study, we aimed to evaluate the efficacy of sentence-combining (SC) and narrative-based (NAR) intervention approaches to syntax intervention using a randomized-controlled-trial design. Method: Fifty-two Cantonese-speaking, school-age children with language impairment were assigned randomly to either the SC or the NAR treatment…

  19. European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP): a randomized trial.

    PubMed

    Landolfi, R; Marchioli, R

    1997-01-01

    Thrombotic complications characterize the clinical course of polycythemia vera (PV) and represent the main cause of morbidity and mortality. However, uncertainty still exists as to the benefit/risk ratio of aspirin prophylaxis in this setting. In vivo platelet biosynthesis of thromboxane A2 is enhanced and can be suppressed by low-dose aspirin in PV, thus providing a rationale for assessing the efficacy and safety of a low-dose aspirin regimen in these patients. The Gruppo Italiano Studio Policitemia Vera has recently performed a pilot study on 112 patients randomized to receive aspirin, 40 mg daily, or placebo and followed for 16 +/- 6 months (mean +/- SD). This study showed that low-dose aspirin is well tolerated in PV patients, and that a large-scale efficacy trial is feasible in this setting. In this article we report the protocol of the European Collaboration on Low-dose Aspirin in Polycythemia Vera (ECLAP) study, which is a randomized trial designed to assess the risk/benefit ratio of low-dose aspirin in PV. To estimate the size and the follow-up duration required for the ECLAP trial, a retrospective analysis of the clinical epidemiology of a large PV population has recently been completed by the Gruppo Italiano Studio Policitemia Vera. On this basis, approximately 3500 patients will be enrolled in the ECLAP study with a follow-up of 3 to 4 years. The uncertainty principle will be used as the main eligibility criterion: Polycythemic patients of any age, having no clear indication for or contraindication to aspirin treatment, will be randomized in a double-blind fashion to receive oral aspirin (100 mg daily) or placebo. According to current therapeutic recommendations, the basic treatment of randomized patients should be aimed at maintaining the hematocrit value < or = 45% in subjects aged < or = 50, and hematocrit < 45% as well as platelet count < 400 x 10(9)/L in patients aged > 50. Randomization will be stratified by participating center. The study is

  20. Preliminary appraisal of the effects of land use on water quality in stratified-drift aquifers in Connecticut

    USGS Publications Warehouse

    Grady, S.J.; Weaver, M.F.

    1988-01-01

    The stratified-drift aquifers that underlie 7.9 sq mi of the Potatuck and 12.7 sq mi of the Pomperaug River valley, CT, consist primarily of sand and gravel deposits up to 150 ft thick. Average horizontal hydraulic conductivity of the stratified drift ranges from 20 to 170 ft/day, and groundwater flows through the aquifers at an average rate of 2 to 3 ft/day. Land use in the study areas is changing from primarily undeveloped or agricultural lands to expanding residential, commercial, and light-industrial uses. Water quality data for 1923-82, that include 127 partial chemical analyses of groundwater samples from 38 wells in the two aquifers, were augmented by sampling during 1985 from 21 new stainless-steel wells for selected major inorganic constituents, trace elements, and organic chemicals. Nonparametric statistical procedures were used to compare the water quality data from four land use areas, for the two sampling periods, and between the two aquifers. Human activities associated with agricultural, residential, and industrial/commercial land uses have affected the quality of water in the stratified-drift aquifers underlying these land use areas. Statistical comparisons of water quality data between land use areas show significant differences, with the apparent relations between land use and groundwater being: (1) Median concentrations of most groundwater constituents are smallest in undeveloped areas; (2) Groundwater in agricultural areas has the largest median sulfate and total ammonia plus organic nitrogen concentrations. Agricultural areas are also characterized by groundwater with significantly greater median specific conductance, noncarbonate hardness, carbon dioxide, and magnesium concentrations relative to undeveloped areas; (3) Median concentrations of most major inorganic constituents, excluding potassium, sulfate, and total ammonia plus organic nitrogen, are greater in groundwater in residential areas than in undeveloped and agricultural areas. (4

  1. [Epidemiology of ageing in Northeastern Brazil: results of a household survey].

    PubMed

    Coelho Filho, J M; Ramos, L R

    1999-10-01

    The population of Brazil is ageing very rapidly, and the care of the elderly is an emerging priority. Up to this date, there is no comprehensive study addressing the profile of the elderly in Northeastern Brazil. The objective is to compile the multidimensional profile of the elderly residents in a metropolitan area of Northeastern Brazil. Six hundred sixty-seven elderly (60 years and over), residents in the city of Fortaleza, Ceará, Brazil, constituting a multistage random sample stratified by socioeconomic status. The data was gathered by household survey using a multidimensional functional assessment questionnaire. The majority of the elderly were living in multigenerational households (75,3%). More than half (51,9%) lived without the spouse; 92,4% mentioned at least one disease; 26,4% were considered psychiatric cases; 47,7% showed loss of autonomy; 6,6% were hospitalized, and 61,4% used health services within the twelve and six months preceding the interview, respectively. The prevalence of multigenerational households, loss of autonomy and psychiatric morbidity were higher in the poorest areas. The elderly population in the city of Fortaleza lives mainly in multigenerational households, with physical and mental morbidity rates particularly high in poor areas, they represent special concern in terms of burden for the social and health services in the next decades

  2. Target-D: a stratified individually randomized controlled trial of the diamond clinical prediction tool to triage and target treatment for depressive symptoms in general practice: study protocol for a randomized controlled trial.

    PubMed

    Gunn, Jane; Wachtler, Caroline; Fletcher, Susan; Davidson, Sandra; Mihalopoulos, Cathrine; Palmer, Victoria; Hegarty, Kelsey; Coe, Amy; Murray, Elizabeth; Dowrick, Christopher; Andrews, Gavin; Chondros, Patty

    2017-07-20

    Depression is a highly prevalent and costly disorder. Effective treatments are available but are not always delivered to the right person at the right time, with both under- and over-treatment a problem. Up to half the patients presenting to general practice report symptoms of depression, but general practitioners have no systematic way of efficiently identifying level of need and allocating treatment accordingly. Therefore, our team developed a new clinical prediction tool (CPT) to assist with this task. The CPT predicts depressive symptom severity in three months' time and based on these scores classifies individuals into three groups (minimal/mild, moderate, severe), then provides a matched treatment recommendation. This study aims to test whether using the CPT reduces depressive symptoms at three months compared with usual care. The Target-D study is an individually randomized controlled trial. Participants will be 1320 general practice patients with depressive symptoms who will be approached in the practice waiting room by a research assistant and invited to complete eligibility screening on an iPad. Eligible patients will provide informed consent and complete the CPT on a purpose-built website. A computer-generated allocation sequence stratified by practice and depressive symptom severity group, will randomly assign participants to intervention (treatment recommendation matched to predicted depressive symptom severity group) or comparison (usual care plus Target-D attention control) arms. Follow-up assessments will be completed online at three and 12 months. The primary outcome is depressive symptom severity at three months. Secondary outcomes include anxiety, mental health self-efficacy, quality of life, and cost-effectiveness. Intention-to-treat analyses will test for differences in outcome means between study arms overall and by depressive symptom severity group. To our knowledge, this is the first depressive symptom stratification tool designed for

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

    PubMed

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

    2017-04-01

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

  4. Invited Review. Combustion instability in spray-guided stratified-charge engines. A review

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fansler, Todd D.; Reuss, D. L.; Sick, V.

    2015-02-02

    Our article reviews systematic research on combustion instabilities (principally rare, random misfires and partial burns) in spray-guided stratified-charge (SGSC) engines operated at part load with highly stratified fuel -air -residual mixtures. Results from high-speed optical imaging diagnostics and numerical simulation provide a conceptual framework and quantify the sensitivity of ignition and flame propagation to strong, cyclically varying temporal and spatial gradients in the flow field and in the fuel -air -residual distribution. For SGSC engines using multi-hole injectors, spark stretching and locally rich ignition are beneficial. Moreover, combustion instability is dominated by convective flow fluctuations that impede motion of themore » spark or flame kernel toward the bulk of the fuel, coupled with low flame speeds due to locally lean mixtures surrounding the kernel. In SGSC engines using outwardly opening piezo-electric injectors, ignition and early flame growth are strongly influenced by the spray's characteristic recirculation vortex. For both injection systems, the spray and the intake/compression-generated flow field influence each other. Factors underlying the benefits of multi-pulse injection are identified. Finally, some unresolved questions include (1) the extent to which piezo-SGSC misfires are caused by failure to form a flame kernel rather than by flame-kernel extinction (as in multi-hole SGSC engines); (2) the relative contributions of partially premixed flame propagation and mixing-controlled combustion under the exceptionally late-injection conditions that permit SGSC operation on E85-like fuels with very low NO x and soot emissions; and (3) the effects of flow-field variability on later combustion, where fuel-air-residual mixing within the piston bowl becomes important.« less

  5. The 'number needed to sample' in primary care research. Comparison of two primary care sampling frames for chronic back pain.

    PubMed

    Smith, Blair H; Hannaford, Philip C; Elliott, Alison M; Smith, W Cairns; Chambers, W Alastair

    2005-04-01

    Sampling for primary care research must strike a balance between efficiency and external validity. For most conditions, even a large population sample will yield a small number of cases, yet other sampling techniques risk problems with extrapolation of findings. To compare the efficiency and external validity of two sampling methods for both an intervention study and epidemiological research in primary care--a convenience sample and a general population sample--comparing the response and follow-up rates, the demographic and clinical characteristics of each sample, and calculating the 'number needed to sample' (NNS) for a hypothetical randomized controlled trial. In 1996, we selected two random samples of adults from 29 general practices in Grampian, for an epidemiological study of chronic pain. One sample of 4175 was identified by an electronic questionnaire that listed patients receiving regular analgesic prescriptions--the 'repeat prescription sample'. The other sample of 5036 was identified from all patients on practice lists--the 'general population sample'. Questionnaires, including demographic, pain and general health measures, were sent to all. A similar follow-up questionnaire was sent in 2000 to all those agreeing to participate in further research. We identified a potential group of subjects for a hypothetical trial in primary care based on a recently published trial (those aged 25-64, with severe chronic back pain, willing to participate in further research). The repeat prescription sample produced better response rates than the general sample overall (86% compared with 82%, P < 0.001), from both genders and from the oldest and youngest age groups. The NNS using convenience sampling was 10 for each member of the final potential trial sample, compared with 55 using general population sampling. There were important differences between the samples in age, marital and employment status, social class and educational level. However, among the potential trial

  6. Ground-water resources in New Hampshire; stratified-drift aquifers

    USGS Publications Warehouse

    Medalie, Laura; Moore, R.B.

    1995-01-01

    Stratified-drift aquifers underlie about 14 percent of the land surface in New Hampshire and are an important source of ground water for commercial, industrial, domestic, and public-water supplies in the State. This report introduces terms and concepts relevant to ground-water resources, summarizes some of the important information derived from a statewide stratified-drift-aquifer investigation, and provides examples of how the findings are used . The purpose of this report is to provide an overview of the stratified-drift aquifer assessment program, thus making summary information accessible to a broad audience, including legislators, State and local officials, and the public. Different audiences will use the report in different ways . To accommodate the varied audiences, some data are summarized statewide, some are presented by major river basin, and some are provided by town. During data collection, care was taken to use consistent methods for each of the 13 study areas (fig. 1) so that results would be comparable throughout the State . If more specific or detailed information about a particular area of interest is needed, the reader is directed to one or more of the technical reports listed in the Selected References section of this report.

  7. Hydrodynamic Stability Analysis on Sheared Stratified Flow in a Convective Flow Environment

    NASA Astrophysics Data System (ADS)

    Xiao, Yuan; Lin, Wenxian; Armfiled, Steven; Kirkpatrick, Michael; He, Yinghe; Fluid Dynamics Research Group, James Cook University Team; Fluid Dynamics Research Group, University of Sydney Team

    2014-11-01

    A hydrodynamic stability analysis on the convective sheared boundary layer (SCBL) flow, where a sheared stratified flow and a thermally convective flow coexist, is carried out in this study. The linear unstable stratifications representing the convective flow are included in the TaylorGoldstein equations as an unstable factor Jb. A new unstable region corresponding to the convective instability, which is not present in pure sheared stratified flows, is found with the analysis. It is also found that the boundaries of the convective instability regions expand with increasing Jb and interact with the sheared stratified instability region. More results will be presented at the conference

  8. Vitamin E in aging persons with Down syndrome: A randomized, placebo-controlled clinical trial.

    PubMed

    Sano, Mary; Aisen, Paul S; Andrews, Howard F; Tsai, Wei-Yann; Lai, Florence; Dalton, Arthur J

    2016-05-31

    To determine whether vitamin E would slow the progression of cognitive deterioration and dementia in aging persons with Down syndrome (DS). A randomized, double-blind controlled clinical trial was conducted at 21 clinical sites, and researchers trained in research procedures recruited adults with DS older than 50 years to participate. Participants were randomly assigned to receive 1,000 IU of vitamin E orally twice daily for 3 years or identical placebo. The primary outcome was change on the Brief Praxis Test (BPT). Secondary outcomes included incident dementia and measures of clinical global change, cognition, function, and behavior. A total of 337 individuals were randomized, 168 to vitamin E and 169 to placebo. Both groups demonstrated deterioration on the BPT with no difference between drug and placebo. At baseline, 26% were diagnosed with dementia and there was an overall rate of incident dementia of 11%/year with no difference between groups. There was no effect on the secondary outcome measures. Though numerically higher in the treatment group, there was no difference in the number of adverse events (p = 0.079) and deaths (p = 0.086) between groups. Vitamin E did not slow the progression of cognitive deterioration in older individuals with DS. This study provides Class II evidence that vitamin E does not significantly slow the progression of cognitive deterioration in aging persons with DS. © 2016 American Academy of Neurology.

  9. The Gambian Bone and Muscle Ageing Study: Baseline Data from a Prospective Observational African Sub-Saharan Study

    PubMed Central

    Zengin, Ayse; Fulford, Anthony J.; Sawo, Yankuba; Jarjou, Landing M.; Schoenmakers, Inez; Goldberg, Gail; Prentice, Ann; Ward, Kate A.

    2017-01-01

    The Gambian Bone and Muscle Ageing Study is a prospective observational study investigating bone and muscle ageing in men and women from a poor, subsistence farming community of The Gambia, West Africa. Musculoskeletal diseases, including osteoporosis and sarcopenia, form a major part of the current global non-communicable disease burden. By 2050, the vast majority of the world’s ageing population will live in low- and middle-income countries with an estimated two-fold rise in osteoporotic fracture. The study design was to characterise change in bone and muscle outcomes and to identify possible preventative strategies for fracture and sarcopenia in the increasing ageing population. Men and women aged ≥40 years from the Kiang West region of The Gambia were recruited with stratified sampling by sex and age. Baseline measurements were completed in 488 participants in 2012 who were randomly assigned to follow-up between 1.5 and 2 years later. Follow-up measurements were performed on 465 participants approximately 1.7 years after baseline measurements. The data set comprises a wide range of measurements on bone, muscle strength, anthropometry, biochemistry, and dietary intake. Questionnaires were used to obtain information on health, lifestyle, musculoskeletal pain, and reproductive status. Baseline cross-sectional data show preliminary evidence for bone mineral density and muscle loss with age. Men had greater negative differences in total body lean mass with age than women following adjustments for body size. From peripheral quantitative computed tomography scans, greater negative associations between bone outcomes and age at the radius and tibia were shown in women than in men. Ultimately, the findings from The Gambian Bone and Muscle Ageing Study will contribute to the understanding of musculoskeletal health in a transitioning population and better characterise fracture and sarcopenia incidence in The Gambia with an aim to the development of preventative

  10. Shear wave speed estimation by adaptive random sample consensus method.

    PubMed

    Lin, Haoming; Wang, Tianfu; Chen, Siping

    2014-01-01

    This paper describes a new method for shear wave velocity estimation that is capable of extruding outliers automatically without preset threshold. The proposed method is an adaptive random sample consensus (ARANDSAC) and the metric used here is finding the certain percentage of inliers according to the closest distance criterion. To evaluate the method, the simulation and phantom experiment results were compared using linear regression with all points (LRWAP) and radon sum transform (RS) method. The assessment reveals that the relative biases of mean estimation are 20.00%, 4.67% and 5.33% for LRWAP, ARANDSAC and RS respectively for simulation, 23.53%, 4.08% and 1.08% for phantom experiment. The results suggested that the proposed ARANDSAC algorithm is accurate in shear wave speed estimation.

  11. Baroclinic Vortices in Rotating Stratified Shearing Flows: Cyclones, Anticyclones, and Zombie Vortices

    NASA Astrophysics Data System (ADS)

    Hassanzadeh, Pedram

    Large coherent vortices are abundant in geophysical and astrophysical flows. They play significant roles in the Earth's oceans and atmosphere, the atmosphere of gas giants, such as Jupiter, and the protoplanetary disks around forming stars. These vortices are essentially three-dimensional (3D) and baroclinic, and their dynamics are strongly influenced by the rotation and density stratification of their environments. This work focuses on improving our understanding of the physics of 3D baroclinic vortices in rotating and continuously stratified flows using 3D spectral simulations of the Boussinesq equations, as well as simplified mathematical models. The first chapter discusses the big picture and summarizes the results of this work. In Chapter 2, we derive a relationship for the aspect ratio (i.e., vertical half-thickness over horizontal length scale) of steady and slowly-evolving baroclinic vortices in rotating stratified fluids. We show that the aspect ratio is a function of the Brunt-Vaisala frequencies within the vortex and outside the vortex, the Coriolis parameter, and the Rossby number of the vortex. This equation is basically the gradient-wind equation integrated over the vortex, and is significantly different from the previously proposed scaling laws that find the aspect ratio to be only a function of the properties of the background flow, and independent of the dynamics of the vortex. Our relation is valid for cyclones and anticyclones in either the cyclostrophic or geostrophic regimes; it works with vortices in Boussinesq fluids or ideal gases, and non-uniform background density gradient. The relation for the aspect ratio has many consequences for quasi-equilibrium vortices in rotating stratified flows. For example, cyclones must have interiors more stratified than the background flow (i.e., super-stratified), and weak anticyclones must have interiors less stratified than the background (i.e., sub-stratified). In addition, this equation is useful to

  12. Species conservation profiles of a random sample of world spiders I: Agelenidae to Filistatidae

    PubMed Central

    Seppälä, Sini; Henriques, Sérgio; Draney, Michael L; Foord, Stefan; Gibbons, Alastair T; Gomez, Luz A; Kariko, Sarah; Malumbres-Olarte, Jagoba; Milne, Marc; Vink, Cor J

    2018-01-01

    Abstract Background The IUCN Red List of Threatened Species is the most widely used information source on the extinction risk of species. One of the uses of the Red List is to evaluate and monitor the state of biodiversity and a possible approach for this purpose is the Red List Index (RLI). For many taxa, mainly hyperdiverse groups, it is not possible within available resources to assess all known species. In such cases, a random sample of species might be selected for assessment and the results derived from it extrapolated for the entire group - the Sampled Red List Index (SRLI). With the current contribution and the three following papers, we intend to create the first point in time of a future spider SRLI encompassing 200 species distributed across the world. New information A sample of 200 species of spiders were randomly selected from the World Spider Catalogue, an updated global database containing all recognised species names for the group. The 200 selected species where divided taxonomically at the family level and the familes were ordered alphabetically. In this publication, we present the conservation profiles of 46 species belonging to the famillies alphabetically arranged between Agelenidae and Filistatidae, which encompassed Agelenidae, Amaurobiidae, Anyphaenidae, Araneidae, Archaeidae, Barychelidae, Clubionidae, Corinnidae, Ctenidae, Ctenizidae, Cyatholipidae, Dictynidae, Dysderidae, Eresidae and Filistatidae. PMID:29725239

  13. Improving Ambulatory Saliva-Sampling Compliance in Pregnant Women: A Randomized Controlled Study

    PubMed Central

    Moeller, Julian; Lieb, Roselind; Meyer, Andrea H.; Loetscher, Katharina Quack; Krastel, Bettina; Meinlschmidt, Gunther

    2014-01-01

    Objective Noncompliance with scheduled ambulatory saliva sampling is common and has been associated with biased cortisol estimates in nonpregnant subjects. This study is the first to investigate in pregnant women strategies to improve ambulatory saliva-sampling compliance, and the association between sampling noncompliance and saliva cortisol estimates. Methods We instructed 64 pregnant women to collect eight scheduled saliva samples on two consecutive days each. Objective compliance with scheduled sampling times was assessed with a Medication Event Monitoring System and self-reported compliance with a paper-and-pencil diary. In a randomized controlled study, we estimated whether a disclosure intervention (informing women about objective compliance monitoring) and a reminder intervention (use of acoustical reminders) improved compliance. A mixed model analysis was used to estimate associations between women's objective compliance and their diurnal cortisol profiles, and between deviation from scheduled sampling and the cortisol concentration measured in the related sample. Results Self-reported compliance with a saliva-sampling protocol was 91%, and objective compliance was 70%. The disclosure intervention was associated with improved objective compliance (informed: 81%, noninformed: 60%), F(1,60)  = 17.64, p<0.001, but not the reminder intervention (reminders: 68%, without reminders: 72%), F(1,60)  = 0.78, p = 0.379. Furthermore, a woman's increased objective compliance was associated with a higher diurnal cortisol profile, F(2,64) = 8.22, p<0.001. Altered cortisol levels were observed in less objective compliant samples, F(1,705) = 7.38, p = 0.007, with delayed sampling associated with lower cortisol levels. Conclusions The results suggest that in pregnant women, objective noncompliance with scheduled ambulatory saliva sampling is common and is associated with biased cortisol estimates. To improve sampling compliance, results suggest

  14. A post-mortem survey on end-of-life decisions using a representative sample of death certificates in Flanders, Belgium: research protocol

    PubMed Central

    Chambaere, Kenneth; Bilsen, Johan; Cohen, Joachim; Pousset, Geert; Onwuteaka-Philipsen, Bregje; Mortier, Freddy; Deliens, Luc

    2008-01-01

    Background Reliable studies of the incidence and characteristics of medical end-of-life decisions with a certain or possible life shortening effect (ELDs) are indispensable for an evidence-based medical and societal debate on this issue. This article presents the protocol drafted for the 2007 ELD Study in Flanders, Belgium, and outlines how the main aims and challenges of the study (i.e. making reliable incidence estimates of end-of-life decisions, even rare ones, and describing their characteristics; allowing comparability with past ELD studies; guaranteeing strict anonymity given the sensitive nature of the research topic; and attaining a sufficient response rate) are addressed in a post-mortem survey using a representative sample of death certificates. Study design Reliable incidence estimates are achievable by using large at random samples of death certificates of deceased persons in Flanders (aged one year or older). This entails the cooperation of the appropriate administrative authorities. To further ensure the reliability of the estimates and descriptions, especially of less prevalent end-of-life decisions (e.g. euthanasia), a stratified sample is drawn. A questionnaire is sent out to the certifying physician of each death sampled. The questionnaire, tested thoroughly and avoiding emotionally charged terms is based largely on questions that have been validated in previous national and European ELD studies. Anonymity of both patient and physician is guaranteed through a rigorous procedure, involving a lawyer as intermediary between responding physicians and researchers. To increase response we follow the Total Design Method (TDM) with a maximum of three follow-up mailings. Also, a non-response survey is conducted to gain insight into the reasons for lack of response. Discussion The protocol of the 2007 ELD Study in Flanders, Belgium, is appropriate for achieving the objectives of the study; as past studies in Belgium, the Netherlands, and other European

  15. Sampling high-altitude and stratified mating flights of red imported fire ant.

    PubMed

    Fritz, Gary N; Fritz, Ann H; Vander Meer, Robert K

    2011-05-01

    With the exception of an airplane equipped with nets, no method has been developed that successfully samples red imported fire ant, Solenopsis invicta Buren, sexuals in mating/dispersal flights throughout their potential altitudinal trajectories. We developed and tested a method for sampling queens and males during mating flights at altitudinal intervals reaching as high as "140 m. Our trapping system uses an electric winch and a 1.2-m spindle bolted to a swiveling platform. The winch dispenses up to 183 m of Kevlar-core, nylon rope and the spindle stores 10 panels (0.9 by 4.6 m each) of nylon tulle impregnated with Tangle-Trap. The panels can be attached to the rope at various intervals and hoisted into the air by using a 3-m-diameter, helium-filled balloon. Raising or lowering all 10 panels takes approximately 15-20 min. This trap also should be useful for altitudinal sampling of other insects of medical importance.

  16. Random Item Generation Is Affected by Age

    ERIC Educational Resources Information Center

    Multani, Namita; Rudzicz, Frank; Wong, Wing Yiu Stephanie; Namasivayam, Aravind Kumar; van Lieshout, Pascal

    2016-01-01

    Purpose: Random item generation (RIG) involves central executive functioning. Measuring aspects of random sequences can therefore provide a simple method to complement other tools for cognitive assessment. We examine the extent to which RIG relates to specific measures of cognitive function, and whether those measures can be estimated using RIG…

  17. Catholic High Schools and Their Finances. 1986.

    ERIC Educational Resources Information Center

    Augenstein, John J.

    This report is based on a randomly selected and stratified sample of 208 United States Catholic high schools. The sample was stratified by governance (diocesan, parochial/interparochial, and private); five categories of enrollment; and six regions. Data are compared with an earlier study, "The Catholic High School: A National Portrait" and show…

  18. The effect of sampling rate on observed statistics in a correlated random walk

    PubMed Central

    Rosser, G.; Fletcher, A. G.; Maini, P. K.; Baker, R. E.

    2013-01-01

    Tracking the movement of individual cells or animals can provide important information about their motile behaviour, with key examples including migrating birds, foraging mammals and bacterial chemotaxis. In many experimental protocols, observations are recorded with a fixed sampling interval and the continuous underlying motion is approximated as a series of discrete steps. The size of the sampling interval significantly affects the tracking measurements, the statistics computed from observed trajectories, and the inferences drawn. Despite the widespread use of tracking data to investigate motile behaviour, many open questions remain about these effects. We use a correlated random walk model to study the variation with sampling interval of two key quantities of interest: apparent speed and angle change. Two variants of the model are considered, in which reorientations occur instantaneously and with a stationary pause, respectively. We employ stochastic simulations to study the effect of sampling on the distributions of apparent speeds and angle changes, and present novel mathematical analysis in the case of rapid sampling. Our investigation elucidates the complex nature of sampling effects for sampling intervals ranging over many orders of magnitude. Results show that inclusion of a stationary phase significantly alters the observed distributions of both quantities. PMID:23740484

  19. Clustering of geriatric deficits emerges to be an essential feature of ageing - results of a cross-sectional study in Poland

    PubMed Central

    Karolina, Piotrowicz; Agnieszka, Pac; Barbara, Skalska Anna; Jerzy, Chudek; Alicja, Klich-Rączka; Aleksandra, Szybalska; Jean-Pierre, Michel; Tomasz, Grodzicki

    2016-01-01

    The majority of old people suffer from various clinical conditions that affect health, functioning and quality of life. This research is a part of a cross-sectional, nationwide PolSenior Study that provides a comprehensive assessment of eight geriatric impairments and their co-occurrence in a representative sample (3471 participant aged 65-104 years, mean age 78.3 years) of the old adults living in the community in Poland. The participants were recruited randomly from all administrative regions of Poland by a three-stage, proportional, stratified-by-age group selection process. Eight geriatric conditions were assessed: falls, incontinences, cognitive impairment, mood disorders, vision and hearing impairments, malnutrition, and functional dependence. We showed that the most common deficits causing disability were vision and hearing impairments, and mood disorders, with more than two thirds of the participants presented at least one geriatric deficit. We showed that presence any of the analyzed conditions significantly increased the risk for co-occurrence of other examined weaknesses. The highest prevalence odds ratios were for functional dependence and, respectively: malnutrition (8.61, 95%CI: 4.70-15.80), incontinences (8.0, 95%CI:5.93-10.70), and cognitive impairment (7.22; 95%CI:5.91-8.83). We concluded that the majority of the old people living in the community present various clinical conditions that prompt disability. PMID:27794563

  20. Argon-40/Argon-39 Age Spectra of Apollo 17 Highlands Breccia Samples by Laser Step Heating and the Age of the Serenitatis Basin

    NASA Technical Reports Server (NTRS)

    Dalrymple, G. Brent; Ryder, Graham

    1996-01-01

    We have obtained high-resolution (21-63 steps) Ar-40/Ar-39 age spectra using a continuous laser system on 19 submilligram samples of melt rocks and clasts from Apollo 17 samples collected from the pre-Imbrian highlands in the easternmost part of the Serenitatis basin. The samples include poikilitic melt rocks inferred to have been formed in the Serenitatis basin-forming impact, aphanitic melt rock whose compositions vary and whose provenance is uncertain, and granulite, gabbro, and melt clasts. Three of the poikilitic melts have similar age spectrum plateau ages (72395,96, 3893 +/- 16 Ma (2sigma); 72535,7, 3887 +/- 16 Ma; 76315,150, 3900 +/- 16 Ma) with a weighted mean age of 3893 +/- 9 Ma, which we interpret as the best age for the Serenitatis basin- forming impact. Published Ar-40/Ar-39 age spectrum ages of Apollo 17 poikilitic melts are consistent with our new age but are much less precise. Two poikilitic melts did not give plateaus and the maxima in their age spectra indicate ages of greater than or equal to 3869 Ma (72558,7) and greater than or equal to 3743 Ma (77135,178). Plateau ages of two poikilitic melts and two gabbro clasts from 73155 range from 3854 +/- 16 Ma to 3937 +/- 16 Ma and have probably been affected by the ubiquitous (older?) clasts and by post- formation heating (impact) events. Plateau ages from two of the aphanitic melt 'blobs' and two granulites in sample 72255 fall in the narrow range of 3850 q 16 Ma to 3869 q 16 Ma with a weighted mean of 3862 +/- 8 Ma. Two of the aphanitic melt blobs from 72255 have ages of 3883 +/- 16 Ma and greater than or equal to 3894 Ma, whereas a poikilitic melt clast (of different composition from the 'Serenitatis' melts) has an age of 3835 +/- 16 Ma, which is the upper limit for the accretion of 72255. These data suggest that either the aphanitic melts vary in age, as is also suggested by their varying chemical compositions, or they formed in the 72255 accretionary event about 3.84-3.85 Ga and older relict