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Sample records for sample survey methods

  1. Surveying immigrants without sampling frames - evaluating the success of alternative field methods.

    Science.gov (United States)

    Reichel, David; Morales, Laura

    2017-01-01

    This paper evaluates the sampling methods of an international survey, the Immigrant Citizens Survey, which aimed at surveying immigrants from outside the European Union (EU) in 15 cities in seven EU countries. In five countries, no sample frame was available for the target population. Consequently, alternative ways to obtain a representative sample had to be found. In three countries 'location sampling' was employed, while in two countries traditional methods were used with adaptations to reach the target population. The paper assesses the main methodological challenges of carrying out a survey among a group of immigrants for whom no sampling frame exists. The samples of the survey in these five countries are compared to results of official statistics in order to assess the accuracy of the samples obtained through the different sampling methods. It can be shown that alternative sampling methods can provide meaningful results in terms of core demographic characteristics although some estimates differ to some extent from the census results.

  2. Sample Size Calculations for Population Size Estimation Studies Using Multiplier Methods With Respondent-Driven Sampling Surveys.

    Science.gov (United States)

    Fearon, Elizabeth; Chabata, Sungai T; Thompson, Jennifer A; Cowan, Frances M; Hargreaves, James R

    2017-09-14

    While guidance exists for obtaining population size estimates using multiplier methods with respondent-driven sampling surveys, we lack specific guidance for making sample size decisions. To guide the design of multiplier method population size estimation studies using respondent-driven sampling surveys to reduce the random error around the estimate obtained. The population size estimate is obtained by dividing the number of individuals receiving a service or the number of unique objects distributed (M) by the proportion of individuals in a representative survey who report receipt of the service or object (P). We have developed an approach to sample size calculation, interpreting methods to estimate the variance around estimates obtained using multiplier methods in conjunction with research into design effects and respondent-driven sampling. We describe an application to estimate the number of female sex workers in Harare, Zimbabwe. There is high variance in estimates. Random error around the size estimate reflects uncertainty from M and P, particularly when the estimate of P in the respondent-driven sampling survey is low. As expected, sample size requirements are higher when the design effect of the survey is assumed to be greater. We suggest a method for investigating the effects of sample size on the precision of a population size estimate obtained using multipler methods and respondent-driven sampling. Uncertainty in the size estimate is high, particularly when P is small, so balancing against other potential sources of bias, we advise researchers to consider longer service attendance reference periods and to distribute more unique objects, which is likely to result in a higher estimate of P in the respondent-driven sampling survey. ©Elizabeth Fearon, Sungai T Chabata, Jennifer A Thompson, Frances M Cowan, James R Hargreaves. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 14.09.2017.

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

    Science.gov (United States)

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

    2018-01-01

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

  4. Sample size methods for estimating HIV incidence from cross-sectional surveys.

    Science.gov (United States)

    Konikoff, Jacob; Brookmeyer, Ron

    2015-12-01

    Understanding HIV incidence, the rate at which new infections occur in populations, is critical for tracking and surveillance of the epidemic. In this article, we derive methods for determining sample sizes for cross-sectional surveys to estimate incidence with sufficient precision. We further show how to specify sample sizes for two successive cross-sectional surveys to detect changes in incidence with adequate power. In these surveys biomarkers such as CD4 cell count, viral load, and recently developed serological assays are used to determine which individuals are in an early disease stage of infection. The total number of individuals in this stage, divided by the number of people who are uninfected, is used to approximate the incidence rate. Our methods account for uncertainty in the durations of time spent in the biomarker defined early disease stage. We find that failure to account for this uncertainty when designing surveys can lead to imprecise estimates of incidence and underpowered studies. We evaluated our sample size methods in simulations and found that they performed well in a variety of underlying epidemics. Code for implementing our methods in R is available with this article at the Biometrics website on Wiley Online Library. © 2015, The International Biometric Society.

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Kelly L'Engle

    Full Text Available 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

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

    Science.gov (United States)

    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.

  8. Using mark-recapture distance sampling methods on line transect surveys

    Science.gov (United States)

    Burt, Louise M.; Borchers, David L.; Jenkins, Kurt J.; Marques, Tigao A

    2014-01-01

    Mark–recapture distance sampling (MRDS) methods are widely used for density and abundance estimation when the conventional DS assumption of certain detection at distance zero fails, as they allow detection at distance zero to be estimated and incorporated into the overall probability of detection to better estimate density and abundance. However, incorporating MR data in DS models raises survey and analysis issues not present in conventional DS. Conversely, incorporating DS assumptions in MR models raises issues not present in conventional MR. As a result, being familiar with either conventional DS methods or conventional MR methods does not on its own put practitioners in good a position to apply MRDS methods appropriately. This study explains the sometimes subtly different varieties of MRDS survey methods and the associated concepts underlying MRDS models. This is done as far as possible without giving mathematical details – in the hope that this will make the key concepts underlying the methods accessible to a wider audience than if we were to present the concepts via equations.

  9. Galaxy redshift surveys with sparse sampling

    International Nuclear Information System (INIS)

    Chiang, Chi-Ting; Wullstein, Philipp; Komatsu, Eiichiro; Jee, Inh; Jeong, Donghui; Blanc, Guillermo A.; Ciardullo, Robin; Gronwall, Caryl; Hagen, Alex; Schneider, Donald P.; Drory, Niv; Fabricius, Maximilian; Landriau, Martin; Finkelstein, Steven; Jogee, Shardha; Cooper, Erin Mentuch; Tuttle, Sarah; Gebhardt, Karl; Hill, Gary J.

    2013-01-01

    Survey observations of the three-dimensional locations of galaxies are a powerful approach to measure the distribution of matter in the universe, which can be used to learn about the nature of dark energy, physics of inflation, neutrino masses, etc. A competitive survey, however, requires a large volume (e.g., V survey ∼ 10Gpc 3 ) to be covered, and thus tends to be expensive. A ''sparse sampling'' method offers a more affordable solution to this problem: within a survey footprint covering a given survey volume, V survey , we observe only a fraction of the volume. The distribution of observed regions should be chosen such that their separation is smaller than the length scale corresponding to the wavenumber of interest. Then one can recover the power spectrum of galaxies with precision expected for a survey covering a volume of V survey (rather than the volume of the sum of observed regions) with the number density of galaxies given by the total number of observed galaxies divided by V survey (rather than the number density of galaxies within an observed region). We find that regularly-spaced sampling yields an unbiased power spectrum with no window function effect, and deviations from regularly-spaced sampling, which are unavoidable in realistic surveys, introduce calculable window function effects and increase the uncertainties of the recovered power spectrum. On the other hand, we show that the two-point correlation function (pair counting) is not affected by sparse sampling. While we discuss the sparse sampling method within the context of the forthcoming Hobby-Eberly Telescope Dark Energy Experiment, the method is general and can be applied to other galaxy surveys

  10. The rise of survey sampling

    NARCIS (Netherlands)

    Bethlehem, J.

    2009-01-01

    This paper is about the history of survey sampling. It describes how sampling became an accepted scientific method. From the first ideas in 1895 it took some 50 years before the principles of probability sampling were widely accepted. This papers has a focus on developments in official statistics in

  11. Comparing two survey methods of measuring health-related indicators: Lot Quality Assurance Sampling and Demographic Health Surveys.

    Science.gov (United States)

    Anoke, Sarah C; Mwai, Paul; Jeffery, Caroline; Valadez, Joseph J; Pagano, Marcello

    2015-12-01

    Two common methods used to measure indicators for health programme monitoring and evaluation are the demographic and health surveys (DHS) and lot quality assurance sampling (LQAS); each one has different strengths. We report on both methods when utilised in comparable situations. We compared 24 indicators in south-west Uganda, where data for prevalence estimations were collected independently for the two methods in 2011 (LQAS: n = 8876; DHS: n = 1200). Data were stratified (e.g. gender and age) resulting in 37 comparisons. We used a two-sample two-sided Z-test of proportions to compare both methods. The average difference between LQAS and DHS for 37 estimates was 0.062 (SD = 0.093; median = 0.039). The average difference among the 21 failures to reject equality of proportions was 0.010 (SD = 0.041; median = 0.009); among the 16 rejections, it was 0.130 (SD = 0.010, median = 0.118). Seven of the 16 rejections exhibited absolute differences of 0.10 and 0.20 (mean = 0.261, SD = 0.083). There is 75.7% agreement across the two surveys. Both methods yield regional results, but only LQAS provides information at less granular levels (e.g. the district level) where managerial action is taken. The cost advantage and localisation make LQAS feasible to conduct more frequently, and provides the possibility for real-time health outcomes monitoring. © 2015 The Authors. Tropical Medicine & International Health Published by John Wiley & Sons Ltd.

  12. Don't spin the pen: two alternative methods for second-stage sampling in urban cluster surveys

    Directory of Open Access Journals (Sweden)

    Rose Angela MC

    2007-06-01

    Full Text Available Abstract In two-stage cluster surveys, the traditional method used in second-stage sampling (in which the first household in a cluster is selected is time-consuming and may result in biased estimates of the indicator of interest. Firstly, a random direction from the center of the cluster is selected, usually by spinning a pen. The houses along that direction are then counted out to the boundary of the cluster, and one is then selected at random to be the first household surveyed. This process favors households towards the center of the cluster, but it could easily be improved. During a recent meningitis vaccination coverage survey in Maradi, Niger, we compared this method of first household selection to two alternatives in urban zones: 1 using a superimposed grid on the map of the cluster area and randomly selecting an intersection; and 2 drawing the perimeter of the cluster area using a Global Positioning System (GPS and randomly selecting one point within the perimeter. Although we only compared a limited number of clusters using each method, we found the sampling grid method to be the fastest and easiest for field survey teams, although it does require a map of the area. Selecting a random GPS point was also found to be a good method, once adequate training can be provided. Spinning the pen and counting households to the boundary was the most complicated and time-consuming. The two methods tested here represent simpler, quicker and potentially more robust alternatives to spinning the pen for cluster surveys in urban areas. However, in rural areas, these alternatives would favor initial household selection from lower density (or even potentially empty areas. Bearing in mind these limitations, as well as available resources and feasibility, investigators should choose the most appropriate method for their particular survey context.

  13. Analyzing Repeated Measures Marginal Models on Sample Surveys with Resampling Methods

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    James D. Knoke

    2005-12-01

    Full Text Available Packaged statistical software for analyzing categorical, repeated measures marginal models on sample survey data with binary covariates does not appear to be available. Consequently, this report describes a customized SAS program which accomplishes such an analysis on survey data with jackknifed replicate weights for which the primary sampling unit information has been suppressed for respondent confidentiality. First, the program employs the Macro Language and the Output Delivery System (ODS to estimate the means and covariances of indicator variables for the response variables, taking the design into account. Then, it uses PROC CATMOD and ODS, ignoring the survey design, to obtain the design matrix and hypothesis test specifications. Finally, it enters these results into another run of CATMOD, which performs automated direct input of the survey design specifications and accomplishes the appropriate analysis. This customized SAS program can be employed, with minor editing, to analyze general categorical, repeated measures marginal models on sample surveys with replicate weights. Finally, the results of our analysis accounting for the survey design are compared to the results of two alternate analyses of the same data. This comparison confirms that such alternate analyses, which do not properly account for the design, do not produce useful results.

  14. Men who have sex with men in Great Britain: comparing methods and estimates from probability and convenience sample surveys

    Science.gov (United States)

    Prah, Philip; Hickson, Ford; Bonell, Chris; McDaid, Lisa M; Johnson, Anne M; Wayal, Sonali; Clifton, Soazig; Sonnenberg, Pam; Nardone, Anthony; Erens, Bob; Copas, Andrew J; Riddell, Julie; Weatherburn, Peter; Mercer, Catherine H

    2016-01-01

    Objective To examine sociodemographic and behavioural differences between men who have sex with men (MSM) participating in recent UK convenience surveys and a national probability sample survey. Methods We compared 148 MSM aged 18–64 years interviewed for Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) undertaken in 2010–2012, with men in the same age range participating in contemporaneous convenience surveys of MSM: 15 500 British resident men in the European MSM Internet Survey (EMIS); 797 in the London Gay Men's Sexual Health Survey; and 1234 in Scotland's Gay Men's Sexual Health Survey. Analyses compared men reporting at least one male sexual partner (past year) on similarly worded questions and multivariable analyses accounted for sociodemographic differences between the surveys. Results MSM in convenience surveys were younger and better educated than MSM in Natsal-3, and a larger proportion identified as gay (85%–95% vs 62%). Partner numbers were higher and same-sex anal sex more common in convenience surveys. Unprotected anal intercourse was more commonly reported in EMIS. Compared with Natsal-3, MSM in convenience surveys were more likely to report gonorrhoea diagnoses and HIV testing (both past year). Differences between the samples were reduced when restricting analysis to gay-identifying MSM. Conclusions National probability surveys better reflect the population of MSM but are limited by their smaller samples of MSM. Convenience surveys recruit larger samples of MSM but tend to over-represent MSM identifying as gay and reporting more sexual risk behaviours. Because both sampling strategies have strengths and weaknesses, methods are needed to triangulate data from probability and convenience surveys. PMID:26965869

  15. Sampling methods. A survey of methods in use in the Nordic countries

    International Nuclear Information System (INIS)

    Isaksson, M.

    2000-10-01

    This report is a survey of sampling techniques currently in use for radioactivity measurements in the Nordic countries, but restricted to sampling techniques for pasture, soil and deposition in emergency situations. It is found that the participating laboratories apply similar sampling procedures for pasture, including cutting height and size of sampled areas. Soil samples are generally taken by some sort of corer of different diameter. The number of cores taken varies, different sampling patterns are used, and pooling of the samples is done by some of the laboratories. The analysis of pasture and of soil is made with Nal-detectors or by high-resolution gamma spectrometry on fresh or dried samples. Precipitation collectors of a range of sizes are used to determine the activity concentration in precipitation and of dry deposited radionuclides. The analysis is made with high-resolution gamma-spectrometry, either directly on a water sample or on ion exchange resins. (au)

  16. New methods for sampling sparse populations

    Science.gov (United States)

    Anna Ringvall

    2007-01-01

    To improve surveys of sparse objects, methods that use auxiliary information have been suggested. Guided transect sampling uses prior information, e.g., from aerial photographs, for the layout of survey strips. Instead of being laid out straight, the strips will wind between potentially more interesting areas. 3P sampling (probability proportional to prediction) uses...

  17. A Study on the Representative Sampling Survey for Radionuclide Analysis of RI Waste

    Energy Technology Data Exchange (ETDEWEB)

    Jee, K. Y. [KAERI, Daejeon (Korea, Republic of); Kim, Juyoul; Jung, Gunhyo [FNC Tech. Co., Daejeon (Korea, Republic of)

    2007-07-15

    We developed a quantitative method for attaining a representative sample during sampling survey of RI waste. Considering a source, process, and type of RI waste, the method computes the number of sample, confidence interval, variance, and coefficient of variance. We also systematize the method of sampling survey logically and quantitatively. The result of this study can be applied to sampling survey of low- and intermediate-level waste generated from nuclear power plant during the transfer process to disposal facility.

  18. Choosing a Cluster Sampling Design for Lot Quality Assurance Sampling Surveys

    OpenAIRE

    Hund, Lauren; Bedrick, Edward J.; Pagano, Marcello

    2015-01-01

    Lot quality assurance sampling (LQAS) surveys are commonly used for monitoring and evaluation in resource-limited settings. Recently several methods have been proposed to combine LQAS with cluster sampling for more timely and cost-effective data collection. For some of these methods, the standard binomial model can be used for constructing decision rules as the clustering can be ignored. For other designs, considered here, clustering is accommodated in the design phase. In this paper, we comp...

  19. Choosing a Cluster Sampling Design for Lot Quality Assurance Sampling Surveys.

    Directory of Open Access Journals (Sweden)

    Lauren Hund

    Full Text Available Lot quality assurance sampling (LQAS surveys are commonly used for monitoring and evaluation in resource-limited settings. Recently several methods have been proposed to combine LQAS with cluster sampling for more timely and cost-effective data collection. For some of these methods, the standard binomial model can be used for constructing decision rules as the clustering can be ignored. For other designs, considered here, clustering is accommodated in the design phase. In this paper, we compare these latter cluster LQAS methodologies and provide recommendations for choosing a cluster LQAS design. We compare technical differences in the three methods and determine situations in which the choice of method results in a substantively different design. We consider two different aspects of the methods: the distributional assumptions and the clustering parameterization. Further, we provide software tools for implementing each method and clarify misconceptions about these designs in the literature. We illustrate the differences in these methods using vaccination and nutrition cluster LQAS surveys as example designs. The cluster methods are not sensitive to the distributional assumptions but can result in substantially different designs (sample sizes depending on the clustering parameterization. However, none of the clustering parameterizations used in the existing methods appears to be consistent with the observed data, and, consequently, choice between the cluster LQAS methods is not straightforward. Further research should attempt to characterize clustering patterns in specific applications and provide suggestions for best-practice cluster LQAS designs on a setting-specific basis.

  20. Choosing a Cluster Sampling Design for Lot Quality Assurance Sampling Surveys.

    Science.gov (United States)

    Hund, Lauren; Bedrick, Edward J; Pagano, Marcello

    2015-01-01

    Lot quality assurance sampling (LQAS) surveys are commonly used for monitoring and evaluation in resource-limited settings. Recently several methods have been proposed to combine LQAS with cluster sampling for more timely and cost-effective data collection. For some of these methods, the standard binomial model can be used for constructing decision rules as the clustering can be ignored. For other designs, considered here, clustering is accommodated in the design phase. In this paper, we compare these latter cluster LQAS methodologies and provide recommendations for choosing a cluster LQAS design. We compare technical differences in the three methods and determine situations in which the choice of method results in a substantively different design. We consider two different aspects of the methods: the distributional assumptions and the clustering parameterization. Further, we provide software tools for implementing each method and clarify misconceptions about these designs in the literature. We illustrate the differences in these methods using vaccination and nutrition cluster LQAS surveys as example designs. The cluster methods are not sensitive to the distributional assumptions but can result in substantially different designs (sample sizes) depending on the clustering parameterization. However, none of the clustering parameterizations used in the existing methods appears to be consistent with the observed data, and, consequently, choice between the cluster LQAS methods is not straightforward. Further research should attempt to characterize clustering patterns in specific applications and provide suggestions for best-practice cluster LQAS designs on a setting-specific basis.

  1. Men who have sex with men in Great Britain: comparing methods and estimates from probability and convenience sample surveys.

    Science.gov (United States)

    Prah, Philip; Hickson, Ford; Bonell, Chris; McDaid, Lisa M; Johnson, Anne M; Wayal, Sonali; Clifton, Soazig; Sonnenberg, Pam; Nardone, Anthony; Erens, Bob; Copas, Andrew J; Riddell, Julie; Weatherburn, Peter; Mercer, Catherine H

    2016-09-01

    To examine sociodemographic and behavioural differences between men who have sex with men (MSM) participating in recent UK convenience surveys and a national probability sample survey. We compared 148 MSM aged 18-64 years interviewed for Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) undertaken in 2010-2012, with men in the same age range participating in contemporaneous convenience surveys of MSM: 15 500 British resident men in the European MSM Internet Survey (EMIS); 797 in the London Gay Men's Sexual Health Survey; and 1234 in Scotland's Gay Men's Sexual Health Survey. Analyses compared men reporting at least one male sexual partner (past year) on similarly worded questions and multivariable analyses accounted for sociodemographic differences between the surveys. MSM in convenience surveys were younger and better educated than MSM in Natsal-3, and a larger proportion identified as gay (85%-95% vs 62%). Partner numbers were higher and same-sex anal sex more common in convenience surveys. Unprotected anal intercourse was more commonly reported in EMIS. Compared with Natsal-3, MSM in convenience surveys were more likely to report gonorrhoea diagnoses and HIV testing (both past year). Differences between the samples were reduced when restricting analysis to gay-identifying MSM. National probability surveys better reflect the population of MSM but are limited by their smaller samples of MSM. Convenience surveys recruit larger samples of MSM but tend to over-represent MSM identifying as gay and reporting more sexual risk behaviours. Because both sampling strategies have strengths and weaknesses, methods are needed to triangulate data from probability and convenience surveys. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  2. Use of methods for specifying the target difference in randomised controlled trial sample size calculations: Two surveys of trialists' practice.

    Science.gov (United States)

    Cook, Jonathan A; Hislop, Jennifer M; Altman, Doug G; Briggs, Andrew H; Fayers, Peter M; Norrie, John D; Ramsay, Craig R; Harvey, Ian M; Vale, Luke D

    2014-06-01

    the most recent trial, the target difference was usually one viewed as important by a stakeholder group, mostly also viewed as a realistic difference given the interventions under evaluation, and sometimes one that led to an achievable sample size. The response rates achieved were relatively low despite the surveys being short, well presented, and having utilised reminders. Substantial variations in practice exist with awareness, use, and willingness to recommend methods varying substantially. The findings support the view that sample size calculation is a more complex process than would appear to be the case from trial reports and protocols. Guidance on approaches for sample size estimation may increase both awareness and use of appropriate formal methods. © The Author(s), 2014.

  3. Optimal sampling designs for large-scale fishery sample surveys in Greece

    Directory of Open Access Journals (Sweden)

    G. BAZIGOS

    2007-12-01

    The paper deals with the optimization of the following three large scale sample surveys: biological sample survey of commercial landings (BSCL, experimental fishing sample survey (EFSS, and commercial landings and effort sample survey (CLES.

  4. Methods of the National Nutrition Survey 1999

    OpenAIRE

    Resano-Pérez, Elsa; Méndez-Ramírez, Ignacio; Shamah-Levy, Teresa; Rivera, Juan A; Sepúlveda-Amor, Jaime

    2003-01-01

    OBJECTIVE: To describe the methods and analyses of the 1999 National Nutrition Survey (NNS-99). MATERIAL AND METHODS: The 1999 National Nutrition Survey (NNS-99) is a probabilistic survey with nationwide representativity. The NNS-99 included four regions and urban and rural areas of Mexico. The last sampling units were households, selected through stratified cluster sampling. The study population consisted of children under five years of age, school-age children (6-11 years), and women of chi...

  5. Men who have sex with men in Great Britain: comparing methods and estimates from probability and convenience sample surveys

    OpenAIRE

    Prah, Philip; Hickson, Ford; Bonell, Chris; McDaid, Lisa M; Johnson, Anne M; Wayal, Sonali; Clifton, Soazig; Sonnenberg, Pam; Nardone, Anthony; Erens, Bob; Copas, Andrew J; Riddell, Julie; Weatherburn, Peter; Mercer, Catherine H

    2016-01-01

    Objective: To examine sociodemographic and behavioural differences between men whohave sex with men (MSM) participating in recent UK convenience surveys and a national probability sample survey.\\ud Methods: We compared 148 MSM aged 18–64 years interviewed for Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3) undertaken in 2010–2012, with men inthe same age range participating in contemporaneous convenience surveys of MSM: 15 500 British resident men in the European...

  6. Sampling in health geography: reconciling geographical objectives and probabilistic methods. An example of a health survey in Vientiane (Lao PDR

    Directory of Open Access Journals (Sweden)

    Bochaton Audrey

    2007-06-01

    Full Text Available Abstract Background Geographical objectives and probabilistic methods are difficult to reconcile in a unique health survey. Probabilistic methods focus on individuals to provide estimates of a variable's prevalence with a certain precision, while geographical approaches emphasise the selection of specific areas to study interactions between spatial characteristics and health outcomes. A sample selected from a small number of specific areas creates statistical challenges: the observations are not independent at the local level, and this results in poor statistical validity at the global level. Therefore, it is difficult to construct a sample that is appropriate for both geographical and probability methods. Methods We used a two-stage selection procedure with a first non-random stage of selection of clusters. Instead of randomly selecting clusters, we deliberately chose a group of clusters, which as a whole would contain all the variation in health measures in the population. As there was no health information available before the survey, we selected a priori determinants that can influence the spatial homogeneity of the health characteristics. This method yields a distribution of variables in the sample that closely resembles that in the overall population, something that cannot be guaranteed with randomly-selected clusters, especially if the number of selected clusters is small. In this way, we were able to survey specific areas while minimising design effects and maximising statistical precision. Application We applied this strategy in a health survey carried out in Vientiane, Lao People's Democratic Republic. We selected well-known health determinants with unequal spatial distribution within the city: nationality and literacy. We deliberately selected a combination of clusters whose distribution of nationality and literacy is similar to the distribution in the general population. Conclusion This paper describes the conceptual reasoning behind

  7. Survey Methods, Traditional, Public Opinion Polling

    DEFF Research Database (Denmark)

    Elmelund-Præstekær, Christian; Hopmann, David Nicolas; Pedersen, Rasmus Tue

    2017-01-01

    Traditional public opinion polls are surveys in which a random sample of a given population is asked questions about their attitudes, knowledge, or behavior. If conducted properly, the answers from such surveys are approximately representative of the entire population. Traditional public opinion...... polling is typically based on four different methods of data gathering, or combinations hereof: face-to-face, postal surveys, phone surveys, and web surveys. Given that opinion polls are based on a sample, we cannot be sure that the sample reflects public opinion perfectly, however—even if randomness...... is perfect. Moreover, responses may be highly dependent on the contextual information provided with the question. Also, it may be difficult to capture past or complex causes of attitudes or behavior. In short, surveys are a precise way of measuring public opinion, but they do not come without challenges....

  8. Sample survey methods as a quality assurance tool in a general practice immunisation audit.

    Science.gov (United States)

    Cullen, R

    1994-04-27

    In a multidoctor family practice there are often just too many sets of patients records to make it practical to repeat an audit by census of even an age band of the practice on a regular basis. This paper attempts to demonstrate how sample survey methodology can be incorporated into the quality assurance cycle. A simple random sample (with replacement) of 120 from 580 children with permanent records who were aged between 6 weeks and 2 years old from an Auckland general practice was performed, with sample size selected to give a predetermined precision. The survey was then repeated after 4 weeks. Both surveys were able to be completed within the course of a normal working day. An unexpectedly low level of under 2 years olds that were recorded as not overdue for any immunisations was found (22.5%) with only a modest improvement after a standard telephone/letter catch up campaign. Seventy-two percent of the sample held a group one community services card. The advantages of properly conducted sample surveys in producing useful estimates of known precision without disrupting office routines excessively were demonstrated. Through some attention to methodology, the trauma of a practice census can be avoided.

  9. A Bayesian Justification for Random Sampling in Sample Survey

    Directory of Open Access Journals (Sweden)

    Glen Meeden

    2012-07-01

    Full Text Available In the usual Bayesian approach to survey sampling the sampling design, plays a minimal role, at best. Although a close relationship between exchangeable prior distributions and simple random sampling has been noted; how to formally integrate simple random sampling into the Bayesian paradigm is not clear. Recently it has been argued that the sampling design can be thought of as part of a Bayesian's prior distribution. We will show here that under this scenario simple random sample can be given a Bayesian justification in survey sampling.

  10. Sampling in health geography: reconciling geographical objectives and probabilistic methods. An example of a health survey in Vientiane (Lao PDR).

    Science.gov (United States)

    Vallée, Julie; Souris, Marc; Fournet, Florence; Bochaton, Audrey; Mobillion, Virginie; Peyronnie, Karine; Salem, Gérard

    2007-06-01

    Geographical objectives and probabilistic methods are difficult to reconcile in a unique health survey. Probabilistic methods focus on individuals to provide estimates of a variable's prevalence with a certain precision, while geographical approaches emphasise the selection of specific areas to study interactions between spatial characteristics and health outcomes. A sample selected from a small number of specific areas creates statistical challenges: the observations are not independent at the local level, and this results in poor statistical validity at the global level. Therefore, it is difficult to construct a sample that is appropriate for both geographical and probability methods. We used a two-stage selection procedure with a first non-random stage of selection of clusters. Instead of randomly selecting clusters, we deliberately chose a group of clusters, which as a whole would contain all the variation in health measures in the population. As there was no health information available before the survey, we selected a priori determinants that can influence the spatial homogeneity of the health characteristics. This method yields a distribution of variables in the sample that closely resembles that in the overall population, something that cannot be guaranteed with randomly-selected clusters, especially if the number of selected clusters is small. In this way, we were able to survey specific areas while minimising design effects and maximising statistical precision. We applied this strategy in a health survey carried out in Vientiane, Lao People's Democratic Republic. We selected well-known health determinants with unequal spatial distribution within the city: nationality and literacy. We deliberately selected a combination of clusters whose distribution of nationality and literacy is similar to the distribution in the general population. This paper describes the conceptual reasoning behind the construction of the survey sample and shows that it can be

  11. Improving the collection of knowledge, attitude and practice data with community surveys: a comparison of two second-stage sampling methods.

    Science.gov (United States)

    Davis, Rosemary H; Valadez, Joseph J

    2014-12-01

    Second-stage sampling techniques, including spatial segmentation, are widely used in community health surveys when reliable household sampling frames are not available. In India, an unresearched technique for household selection is used in eight states, which samples the house with the last marriage or birth as the starting point. Users question whether this last-birth or last-marriage (LBLM) approach introduces bias affecting survey results. We conducted two simultaneous population-based surveys. One used segmentation sampling; the other used LBLM. LBLM sampling required modification before assessment was possible and a more systematic approach was tested using last birth only. We compared coverage proportions produced by the two independent samples for six malaria indicators and demographic variables (education, wealth and caste). We then measured the level of agreement between the caste of the selected participant and the caste of the health worker making the selection. No significant difference between methods was found for the point estimates of six malaria indicators, education, caste or wealth of the survey participants (range of P: 0.06 to >0.99). A poor level of agreement occurred between the caste of the health worker used in household selection and the caste of the final participant, (Κ = 0.185), revealing little association between the two, and thereby indicating that caste was not a source of bias. Although LBLM was not testable, a systematic last-birth approach was tested. If documented concerns of last-birth sampling are addressed, this new method could offer an acceptable alternative to segmentation in India. However, inter-state caste variation could affect this result. Therefore, additional assessment of last birth is required before wider implementation is recommended. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2013; all rights reserved.

  12. Emigration Rates From Sample Surveys: An Application to Senegal.

    Science.gov (United States)

    Willekens, Frans; Zinn, Sabine; Leuchter, Matthias

    2017-12-01

    What is the emigration rate of a country, and how reliable is that figure? Answering these questions is not at all straightforward. Most data on international migration are census data on foreign-born population. These migrant stock data describe the immigrant population in destination countries but offer limited information on the rate at which people leave their country of origin. The emigration rate depends on the number leaving in a given period and the population at risk of leaving, weighted by the duration at risk. Emigration surveys provide a useful data source for estimating emigration rates, provided that the estimation method accounts for sample design. In this study, emigration rates and confidence intervals are estimated from a sample survey of households in the Dakar region in Senegal, which was part of the Migration between Africa and Europe survey. The sample was a stratified two-stage sample with oversampling of households with members abroad or return migrants. A combination of methods of survival analysis (time-to-event data) and replication variance estimation (bootstrapping) yields emigration rates and design-consistent confidence intervals that are representative for the study population.

  13. Statistical sampling method for releasing decontaminated vehicles

    International Nuclear Information System (INIS)

    Lively, J.W.; Ware, J.A.

    1996-01-01

    Earth moving vehicles (e.g., dump trucks, belly dumps) commonly haul radiologically contaminated materials from a site being remediated to a disposal site. Traditionally, each vehicle must be surveyed before being released. The logistical difficulties of implementing the traditional approach on a large scale demand that an alternative be devised. A statistical method (MIL-STD-105E, open-quotes Sampling Procedures and Tables for Inspection by Attributesclose quotes) for assessing product quality from a continuous process was adapted to the vehicle decontamination process. This method produced a sampling scheme that automatically compensates and accommodates fluctuating batch sizes and changing conditions without the need to modify or rectify the sampling scheme in the field. Vehicles are randomly selected (sampled) upon completion of the decontamination process to be surveyed for residual radioactive surface contamination. The frequency of sampling is based on the expected number of vehicles passing through the decontamination process in a given period and the confidence level desired. This process has been successfully used for 1 year at the former uranium mill site in Monticello, Utah (a CERCLA regulated clean-up site). The method forces improvement in the quality of the decontamination process and results in a lower likelihood that vehicles exceeding the surface contamination standards are offered for survey. Implementation of this statistical sampling method on Monticello Projects has resulted in more efficient processing of vehicles through decontamination and radiological release, saved hundreds of hours of processing time, provided a high level of confidence that release limits are met, and improved the radiological cleanliness of vehicles leaving the controlled site

  14. Semi-automatic surface sediment sampling system - A prototype to be implemented in bivalve fishing surveys

    Science.gov (United States)

    Rufino, Marta M.; Baptista, Paulo; Pereira, Fábio; Gaspar, Miguel B.

    2018-01-01

    In the current work we propose a new method to sample surface sediment during bivalve fishing surveys. Fishing institutes all around the word carry out regular surveys with the aim of monitoring the stocks of commercial species. These surveys comprise often more than one hundred of sampling stations and cover large geographical areas. Although superficial sediment grain sizes are among the main drivers of benthic communities and provide crucial information for studies on coastal dynamics, overall there is a strong lack of this type of data, possibly, because traditional surface sediment sampling methods use grabs, that require considerable time and effort to be carried out on regular basis or on large areas. In face of these aspects, we developed an easy and un-expensive method to sample superficial sediments, during bivalve fisheries monitoring surveys, without increasing survey time or human resources. The method was successfully evaluated and validated during a typical bivalve survey carried out on the Northwest coast of Portugal, confirming that it had any interference with the survey objectives. Furthermore, the method was validated by collecting samples using a traditional Van Veen grabs (traditional method), which showed a similar grain size composition to the ones collected by the new method, on the same localities. We recommend that the procedure is implemented on regular bivalve fishing surveys, together with an image analysis system to analyse the collected samples. The new method will provide substantial quantity of data on surface sediment in coastal areas, using a non-expensive and efficient manner, with a high potential application in different fields of research.

  15. The quality of sample surveys in a developing nation

    Directory of Open Access Journals (Sweden)

    Paul A Bourne

    2010-08-01

    Full Text Available Paul A Bourne1, Christopher AD Charles2,3, Neva South-Bourne4, Chloe Morris1, Denise Eldemire-Shearer1, Maureen D Kerr-Campbell51Department of Community Health and Psychiatry, Faculty of Medical Sciences, University of the West Indies, Mona, Kingston, Jamaica; 2King Graduate School, Monroe College, Bronx, New York, USA; 3Center for Victim Support, Harlem Hospital Center, New York, USA; 4Research assistant for Paul A Bourne; 5Systems Development Unit, Main Library, Faculty of Humanities and Education, University of the West Indies, Mona, Kingston, JamaicaBackground: In Jamaica, population census began in 1844, and many intercensal ratios obtained from the census data showed that there is a general high degree of accuracy of the data. However, statistics from the Jamaican Ministry of Health showed that there are inaccuracies in health data collected from males using sample surveys.Objectives: The objectives of the present research are to 1 investigate the accuracy of a national sample survey, 2 explore the feasibility and quality of using a subnational sample survey to represent a national survey, 3 aid other scholars in understanding the probability of using national sample surveys and subnational sample surveys, 4 assess older men’s ­evaluation of their health status, and 5 determine whether dichotomization changes self-evaluated health status.Methods: For the current study, the data used in the analysis were originally collected from 2 different sources: 1 the Jamaica Survey of Living Conditions (JSLC and 2 Survey of Older Men (SOM. Cross validation of self-evaluated data of men in Jamaica was done with comparable samples of the complete JSLC data and the SOM data, where men older than 55 years were selected from each sample.Results: In study 1, 50.2% of respondents indicated at least good self-evaluated health status compared with 74.0% in study 2. Statistical associations were found between health status and survey sample (Χ2 [df = 5

  16. Neonatal blood gas sampling methods | Goenka | South African ...

    African Journals Online (AJOL)

    There is little published guidance that systematically evaluates the different methods of neonatal blood gas sampling, where each method has its individual benefits and risks. This review critically surveys the available evidence to generate a comparison between arterial and capillary blood gas sampling, focusing on their ...

  17. Probability sampling design in ethnobotanical surveys of medicinal plants

    Directory of Open Access Journals (Sweden)

    Mariano Martinez Espinosa

    2012-07-01

    Full Text Available Non-probability sampling design can be used in ethnobotanical surveys of medicinal plants. However, this method does not allow statistical inferences to be made from the data generated. The aim of this paper is to present a probability sampling design that is applicable in ethnobotanical studies of medicinal plants. The sampling design employed in the research titled "Ethnobotanical knowledge of medicinal plants used by traditional communities of Nossa Senhora Aparecida do Chumbo district (NSACD, Poconé, Mato Grosso, Brazil" was used as a case study. Probability sampling methods (simple random and stratified sampling were used in this study. In order to determine the sample size, the following data were considered: population size (N of 1179 families; confidence coefficient, 95%; sample error (d, 0.05; and a proportion (p, 0.5. The application of this sampling method resulted in a sample size (n of at least 290 families in the district. The present study concludes that probability sampling methods necessarily have to be employed in ethnobotanical studies of medicinal plants, particularly where statistical inferences have to be made using data obtained. This can be achieved by applying different existing probability sampling methods, or better still, a combination of such methods.

  18. [Sampling and measurement methods of the protocol design of the China Nine-Province Survey for blindness, visual impairment and cataract surgery].

    Science.gov (United States)

    Zhao, Jia-liang; Wang, Yu; Gao, Xue-cheng; Ellwein, Leon B; Liu, Hu

    2011-09-01

    To design the protocol of the China nine-province survey for blindness, visual impairment and cataract surgery to evaluate the prevalence and main causes of blindness and visual impairment, and the prevalence and outcomes of the cataract surgery. The protocol design was began after accepting the task for the national survey for blindness, visual impairment and cataract surgery from the Department of Medicine, Ministry of Health, China, in November, 2005. The protocol in Beijing Shunyi Eye Study in 1996 and Guangdong Doumen County Eye Study in 1997, both supported by World Health Organization, was taken as the basis for the protocol design. The relative experts were invited to discuss and prove the draft protocol. An international advisor committee was established to examine and approve the draft protocol. Finally, the survey protocol was checked and approved by the Department of Medicine, Ministry of Health, China and Prevention Program of Blindness and Deafness, WHO. The survey protocol was designed according to the characteristics and the scale of the survey. The contents of the protocol included determination of target population and survey sites, calculation of the sample size, design of the random sampling, composition and organization of the survey teams, determination of the examinee, the flowchart of the field work, survey items and methods, diagnostic criteria of blindness and moderate and sever visual impairment, the measures of the quality control, the methods of the data management. The designed protocol became the standard and practical protocol for the survey to evaluate the prevalence and main causes of blindness and visual impairment, and the prevalence and outcomes of the cataract surgery.

  19. National Sample Survey of Registered Nurses

    Data.gov (United States)

    U.S. Department of Health & Human Services — The National Sample Survey of Registered Nurses (NSSRN) Download makes data from the survey readily available to users in a one-stop download. The Survey has been...

  20. A Systematic Review of Published Respondent-Driven Sampling Surveys Collecting Behavioral and Biologic Data.

    Science.gov (United States)

    Johnston, Lisa G; Hakim, Avi J; Dittrich, Samantha; Burnett, Janet; Kim, Evelyn; White, Richard G

    2016-08-01

    Reporting key details of respondent-driven sampling (RDS) survey implementation and analysis is essential for assessing the quality of RDS surveys. RDS is both a recruitment and analytic method and, as such, it is important to adequately describe both aspects in publications. We extracted data from peer-reviewed literature published through September, 2013 that reported collected biological specimens using RDS. We identified 151 eligible peer-reviewed articles describing 222 surveys conducted in seven regions throughout the world. Most published surveys reported basic implementation information such as survey city, country, year, population sampled, interview method, and final sample size. However, many surveys did not report essential methodological and analytical information for assessing RDS survey quality, including number of recruitment sites, seeds at start and end, maximum number of waves, and whether data were adjusted for network size. Understanding the quality of data collection and analysis in RDS is useful for effectively planning public health service delivery and funding priorities.

  1. Mahalanobis' Contributions to Sample Surveys

    Indian Academy of Sciences (India)

    Sample Survey started its operations in October 1950 under the ... and adopted random cuts for estimating the acreage under jute ... demographic factors relating to indebtedness, unemployment, ... traffic surveys, demand for currency coins and average life of .... Mahalanobis derived the optimum allocation in stratified.

  2. Using Linked Survey Paradata to Improve Sampling Strategies in the Medical Expenditure Panel Survey

    Directory of Open Access Journals (Sweden)

    Mirel Lisa B.

    2017-06-01

    Full Text Available Using paradata from a prior survey that is linked to a new survey can help a survey organization develop more effective sampling strategies. One example of this type of linkage or subsampling is between the National Health Interview Survey (NHIS and the Medical Expenditure Panel Survey (MEPS. MEPS is a nationally representative sample of the U.S. civilian, noninstitutionalized population based on a complex multi-stage sample design. Each year a new sample is drawn as a subsample of households from the prior year’s NHIS. The main objective of this article is to examine how paradata from a prior survey can be used in developing a sampling scheme in a subsequent survey. A framework for optimal allocation of the sample in substrata formed for this purpose is presented and evaluated for the relative effectiveness of alternative substratification schemes. The framework is applied, using real MEPS data, to illustrate how utilizing paradata from the linked survey offers the possibility of making improvements to the sampling scheme for the subsequent survey. The improvements aim to reduce the data collection costs while maintaining or increasing effective responding sample sizes and response rates for a harder to reach population.

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

    Science.gov (United States)

    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.

  4. Lot quality assurance sampling techniques in health surveys in developing countries: advantages and current constraints.

    Science.gov (United States)

    Lanata, C F; Black, R E

    1991-01-01

    Traditional survey methods, which are generally costly and time-consuming, usually provide information at the regional or national level only. The utilization of lot quality assurance sampling (LQAS) methodology, developed in industry for quality control, makes it possible to use small sample sizes when conducting surveys in small geographical or population-based areas (lots). This article describes the practical use of LQAS for conducting health surveys to monitor health programmes in developing countries. Following a brief description of the method, the article explains how to build a sample frame and conduct the sampling to apply LQAS under field conditions. A detailed description of the procedure for selecting a sampling unit to monitor the health programme and a sample size is given. The sampling schemes utilizing LQAS applicable to health surveys, such as simple- and double-sampling schemes, are discussed. The interpretation of the survey results and the planning of subsequent rounds of LQAS surveys are also discussed. When describing the applicability of LQAS in health surveys in developing countries, the article considers current limitations for its use by health planners in charge of health programmes, and suggests ways to overcome these limitations through future research. It is hoped that with increasing attention being given to industrial sampling plans in general, and LQAS in particular, their utilization to monitor health programmes will provide health planners in developing countries with powerful techniques to help them achieve their health programme targets.

  5. A two-stage cluster sampling method using gridded population data, a GIS, and Google EarthTM imagery in a population-based mortality survey in Iraq

    Directory of Open Access Journals (Sweden)

    Galway LP

    2012-04-01

    Full Text Available Abstract Background Mortality estimates can measure and monitor the impacts of conflict on a population, guide humanitarian efforts, and help to better understand the public health impacts of conflict. Vital statistics registration and surveillance systems are rarely functional in conflict settings, posing a challenge of estimating mortality using retrospective population-based surveys. Results We present a two-stage cluster sampling method for application in population-based mortality surveys. The sampling method utilizes gridded population data and a geographic information system (GIS to select clusters in the first sampling stage and Google Earth TM imagery and sampling grids to select households in the second sampling stage. The sampling method is implemented in a household mortality study in Iraq in 2011. Factors affecting feasibility and methodological quality are described. Conclusion Sampling is a challenge in retrospective population-based mortality studies and alternatives that improve on the conventional approaches are needed. The sampling strategy presented here was designed to generate a representative sample of the Iraqi population while reducing the potential for bias and considering the context specific challenges of the study setting. This sampling strategy, or variations on it, are adaptable and should be considered and tested in other conflict settings.

  6. Comparability of river suspended-sediment sampling and laboratory analysis methods

    Science.gov (United States)

    Groten, Joel T.; Johnson, Gregory D.

    2018-03-06

    Accurate measurements of suspended sediment, a leading water-quality impairment in many Minnesota rivers, are important for managing and protecting water resources; however, water-quality standards for suspended sediment in Minnesota are based on grab field sampling and total suspended solids (TSS) laboratory analysis methods that have underrepresented concentrations of suspended sediment in rivers compared to U.S. Geological Survey equal-width-increment or equal-discharge-increment (EWDI) field sampling and suspended sediment concentration (SSC) laboratory analysis methods. Because of this underrepresentation, the U.S. Geological Survey, in collaboration with the Minnesota Pollution Control Agency, collected concurrent grab and EWDI samples at eight sites to compare results obtained using different combinations of field sampling and laboratory analysis methods.Study results determined that grab field sampling and TSS laboratory analysis results were biased substantially low compared to EWDI sampling and SSC laboratory analysis results, respectively. Differences in both field sampling and laboratory analysis methods caused grab and TSS methods to be biased substantially low. The difference in laboratory analysis methods was slightly greater than field sampling methods.Sand-sized particles had a strong effect on the comparability of the field sampling and laboratory analysis methods. These results indicated that grab field sampling and TSS laboratory analysis methods fail to capture most of the sand being transported by the stream. The results indicate there is less of a difference among samples collected with grab field sampling and analyzed for TSS and concentration of fines in SSC. Even though differences are present, the presence of strong correlations between SSC and TSS concentrations provides the opportunity to develop site specific relations to address transport processes not captured by grab field sampling and TSS laboratory analysis methods.

  7. The SAGES Legacy Unifying Globulars and Galaxies survey (SLUGGS): sample definition, methods, and initial results

    Energy Technology Data Exchange (ETDEWEB)

    Brodie, Jean P.; Romanowsky, Aaron J.; Jennings, Zachary G.; Pota, Vincenzo; Kader, Justin; Roediger, Joel C.; Villaume, Alexa; Arnold, Jacob A.; Woodley, Kristin A. [University of California Observatories, 1156 High Street, Santa Cruz, CA 95064 (United States); Strader, Jay [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Forbes, Duncan A.; Pastorello, Nicola; Usher, Christopher; Blom, Christina; Kartha, Sreeja S. [Centre for Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122 (Australia); Foster, Caroline; Spitler, Lee R., E-mail: jbrodie@ucsc.edu [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia)

    2014-11-20

    We introduce and provide the scientific motivation for a wide-field photometric and spectroscopic chemodynamical survey of nearby early-type galaxies (ETGs) and their globular cluster (GC) systems. The SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey is being carried out primarily with Subaru/Suprime-Cam and Keck/DEIMOS. The former provides deep gri imaging over a 900 arcmin{sup 2} field-of-view to characterize GC and host galaxy colors and spatial distributions, and to identify spectroscopic targets. The NIR Ca II triplet provides GC line-of-sight velocities and metallicities out to typically ∼8 R {sub e}, and to ∼15 R {sub e} in some cases. New techniques to extract integrated stellar kinematics and metallicities to large radii (∼2-3 R {sub e}) are used in concert with GC data to create two-dimensional (2D) velocity and metallicity maps for comparison with simulations of galaxy formation. The advantages of SLUGGS compared with other, complementary, 2D-chemodynamical surveys are its superior velocity resolution, radial extent, and multiple halo tracers. We describe the sample of 25 nearby ETGs, the selection criteria for galaxies and GCs, the observing strategies, the data reduction techniques, and modeling methods. The survey observations are nearly complete and more than 30 papers have so far been published using SLUGGS data. Here we summarize some initial results, including signatures of two-phase galaxy assembly, evidence for GC metallicity bimodality, and a novel framework for the formation of extended star clusters and ultracompact dwarfs. An integrated overview of current chemodynamical constraints on GC systems points to separate, in situ formation modes at high redshifts for metal-poor and metal-rich GCs.

  8. Statistical literacy and sample survey results

    Science.gov (United States)

    McAlevey, Lynn; Sullivan, Charles

    2010-10-01

    Sample surveys are widely used in the social sciences and business. The news media almost daily quote from them, yet they are widely misused. Using students with prior managerial experience embarking on an MBA course, we show that common sample survey results are misunderstood even by those managers who have previously done a statistics course. In general, they fare no better than managers who have never studied statistics. There are implications for teaching, especially in business schools, as well as for consulting.

  9. Research Methods in Healthcare Epidemiology: Survey and Qualitative Research.

    Science.gov (United States)

    Safdar, Nasia; Abbo, Lilian M; Knobloch, Mary Jo; Seo, Susan K

    2016-11-01

    Surveys are one of the most frequently employed study designs in healthcare epidemiology research. Generally easier to undertake and less costly than many other study designs, surveys can be invaluable to gain insights into opinions and practices in large samples and may be descriptive and/or be used to test associations. In this context, qualitative research methods may complement this study design either at the survey development phase and/or at the interpretation/extension of results stage. This methods article focuses on key considerations for designing and deploying surveys in healthcare epidemiology and antibiotic stewardship, including identification of whether or not de novo survey development is necessary, ways to optimally lay out and display a survey, denominator measurement, discussion of biases to keep in mind particularly in research using surveys, and the role of qualitative research methods to complement surveys. We review examples of surveys in healthcare epidemiology and antimicrobial stewardship and review the pros and cons of methods used. A checklist is provided to help aid design and deployment of surveys in healthcare epidemiology and antimicrobial stewardship. Infect Control Hosp Epidemiol 2016;1-6.

  10. Efficiency of snake sampling methods in the Brazilian semiarid region.

    Science.gov (United States)

    Mesquita, Paula C M D; Passos, Daniel C; Cechin, Sonia Z

    2013-09-01

    The choice of sampling methods is a crucial step in every field survey in herpetology. In countries where time and financial support are limited, the choice of the methods is critical. The methods used to sample snakes often lack objective criteria, and the traditional methods have apparently been more important when making the choice. Consequently researches using not-standardized methods are frequently found in the literature. We have compared four commonly used methods for sampling snake assemblages in a semiarid area in Brazil. We compared the efficacy of each method based on the cost-benefit regarding the number of individuals and species captured, time, and financial investment. We found that pitfall traps were the less effective method in all aspects that were evaluated and it was not complementary to the other methods in terms of abundance of species and assemblage structure. We conclude that methods can only be considered complementary if they are standardized to the objectives of the study. The use of pitfall traps in short-term surveys of the snake fauna in areas with shrubby vegetation and stony soil is not recommended.

  11. Sample design for the residential energy consumption survey

    Energy Technology Data Exchange (ETDEWEB)

    1994-08-01

    The purpose of this report is to provide detailed information about the multistage area-probability sample design used for the Residential Energy Consumption Survey (RECS). It is intended as a technical report, for use by statisticians, to better understand the theory and procedures followed in the creation of the RECS sample frame. For a more cursory overview of the RECS sample design, refer to the appendix entitled ``How the Survey was Conducted,`` which is included in the statistical reports produced for each RECS survey year.

  12. Survey of sampling-based methods for uncertainty and sensitivity analysis

    International Nuclear Information System (INIS)

    Helton, J.C.; Johnson, J.D.; Sallaberry, C.J.; Storlie, C.B.

    2006-01-01

    Sampling-based methods for uncertainty and sensitivity analysis are reviewed. The following topics are considered: (i) definition of probability distributions to characterize epistemic uncertainty in analysis inputs (ii) generation of samples from uncertain analysis inputs (iii) propagation of sampled inputs through an analysis (iv) presentation of uncertainty analysis results, and (v) determination of sensitivity analysis results. Special attention is given to the determination of sensitivity analysis results, with brief descriptions and illustrations given for the following procedures/techniques: examination of scatterplots, correlation analysis, regression analysis, partial correlation analysis, rank transformations, statistical tests for patterns based on gridding, entropy tests for patterns based on gridding, nonparametric regression analysis, squared rank differences/rank correlation coefficient test, two-dimensional Kolmogorov-Smirnov test, tests for patterns based on distance measures, top down coefficient of concordance, and variance decomposition

  13. Survey of sampling-based methods for uncertainty and sensitivity analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Jay Dean; Helton, Jon Craig; Sallaberry, Cedric J. PhD. (.; .); Storlie, Curt B. (Colorado State University, Fort Collins, CO)

    2006-06-01

    Sampling-based methods for uncertainty and sensitivity analysis are reviewed. The following topics are considered: (1) Definition of probability distributions to characterize epistemic uncertainty in analysis inputs, (2) Generation of samples from uncertain analysis inputs, (3) Propagation of sampled inputs through an analysis, (4) Presentation of uncertainty analysis results, and (5) Determination of sensitivity analysis results. Special attention is given to the determination of sensitivity analysis results, with brief descriptions and illustrations given for the following procedures/techniques: examination of scatterplots, correlation analysis, regression analysis, partial correlation analysis, rank transformations, statistical tests for patterns based on gridding, entropy tests for patterns based on gridding, nonparametric regression analysis, squared rank differences/rank correlation coefficient test, two dimensional Kolmogorov-Smirnov test, tests for patterns based on distance measures, top down coefficient of concordance, and variance decomposition.

  14. Assessing risk of draft survey by AHP method

    Science.gov (United States)

    Xu, Guangcheng; Zhao, Kuimin; Zuo, Zhaoying; Liu, Gang; Jian, Binguo; Lin, Yan; Fan, Yukun; Wang, Fei

    2018-04-01

    The paper assesses the risks of vessel floating in the seawater for draft survey by using the analytic hierarchy process. On this basis, the paper established draft survey risk index from the view of draft reading, ballast water, fresh water, and calculation process and so on. Then the paper proposes the method to deal with risk assessment using one concrete sample.

  15. Radiological decontamination, survey, and statistical release method for vehicles

    International Nuclear Information System (INIS)

    Goodwill, M.E.; Lively, J.W.; Morris, R.L.

    1996-06-01

    Earth-moving vehicles (e.g., dump trucks, belly dumps) commonly haul radiologically contaminated materials from a site being remediated to a disposal site. Traditionally, each vehicle must be surveyed before being released. The logistical difficulties of implementing the traditional approach on a large scale demand that an alternative be devised. A statistical method for assessing product quality from a continuous process was adapted to the vehicle decontamination process. This method produced a sampling scheme that automatically compensates and accommodates fluctuating batch sizes and changing conditions without the need to modify or rectify the sampling scheme in the field. Vehicles are randomly selected (sampled) upon completion of the decontamination process to be surveyed for residual radioactive surface contamination. The frequency of sampling is based on the expected number of vehicles passing through the decontamination process in a given period and the confidence level desired. This process has been successfully used for 1 year at the former uranium millsite in Monticello, Utah (a cleanup site regulated under the Comprehensive Environmental Response, Compensation, and Liability Act). The method forces improvement in the quality of the decontamination process and results in a lower likelihood that vehicles exceeding the surface contamination standards are offered for survey. Implementation of this statistical sampling method on Monticello projects has resulted in more efficient processing of vehicles through decontamination and radiological release, saved hundreds of hours of processing time, provided a high level of confidence that release limits are met, and improved the radiological cleanliness of vehicles leaving the controlled site

  16. Research Note Pilot survey to assess sample size for herbaceous ...

    African Journals Online (AJOL)

    A pilot survey to determine sub-sample size (number of point observations per plot) for herbaceous species composition assessments, using a wheel-point apparatus applying the nearest-plant method, was conducted. Three plots differing in species composition on the Zululand coastal plain were selected, and on each plot ...

  17. Sample design considerations of indoor air exposure surveys

    International Nuclear Information System (INIS)

    Cox, B.G.; Mage, D.T.; Immerman, F.W.

    1988-01-01

    Concern about the potential for indoor air pollution has prompted recent surveys of radon and NO 2 concentrations in homes and personal exposure studies of volatile organics, carbon monoxide and pesticides, to name a few. The statistical problems in designing sample surveys that measure the physical environment are diverse and more complicated than those encountered in traditional surveys of human attitudes and attributes. This paper addresses issues encountered when designing indoor air quality (IAQ) studies. General statistical concepts related to target population definition, frame creation, and sample selection for area household surveys and telephone surveys are presented. The implications of different measurement approaches are discussed, and response rate considerations are described

  18. Sampling methods for terrestrial amphibians and reptiles.

    Science.gov (United States)

    Paul Stephen Corn; R. Bruce. Bury

    1990-01-01

    Methods described for sampling amphibians and reptiles in Douglas-fir forests in the Pacific Northwest include pitfall trapping, time-constrained collecting, and surveys of coarse woody debris. The herpetofauna of this region differ in breeding and nonbreeding habitats and vagility, so that no single technique is sufficient for a community study. A combination of...

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

    Science.gov (United States)

    Jung, Minsoo

    2015-01-01

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

  20. Studying Cannabis Use Behaviors With Facebook and Web Surveys: Methods and Insights

    Science.gov (United States)

    2018-01-01

    The rapid and wide-reaching expansion of internet access and digital technologies offers epidemiologists numerous opportunities to study health behaviors. One particularly promising new data collection strategy is the use of Facebook’s advertising platform in conjunction with Web-based surveys. Our research team at the Center for Technology and Behavioral Health has used this quick and cost-efficient method to recruit large samples and address unique scientific questions related to cannabis use. In conducting this research, we have gleaned several insights for using this sampling method effectively and have begun to document the characteristics of the resulting data. We believe this information could be useful to other researchers attempting to study cannabis use or, potentially, other health behaviors. The first aim of this paper is to describe case examples of procedures for using Facebook as a survey sampling method for studying cannabis use. We then present several distinctive features of the data produced using this method. Finally, we discuss the utility of this sampling method for addressing specific types of epidemiological research questions. Overall, we believe that sampling with Facebook advertisements and Web surveys is best conceptualized as a targeted, nonprobability-based method for oversampling cannabis users across the United States. PMID:29720366

  1. METHODS IN THE POST-METHODS ERA. REPORT ON AN INTERNATIONAL SURVEY ON LANGUAGE TEACHING METHODS'

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2004-06-01

    Full Text Available Do methods still have a place in 21" century language teaching? To answer this question, an international survey was conducted in the surnmer of 1999. A sample of 800 language teachers world-wide randomly drawn from 17,800 TESOLers were each given a 2-page survey. The return rate was 58.5% with the actual usable data set of448, which was analyzed by using both descriptive and inferential statistics. Among the ten commonly recognized teaching methods surveyed, both the Communicative Language Teaching Approach and an eclectic method seem to have the highest rate in familiarity, preference, and use. But when multiple factors, such as teaching contexts, instructional settings, learners' proficiency levels, class size, teaching experience and educational backgrounds of the teachers, and the status of being a native or nonnative English speaking professional were taken into consideration, various patterns and themes emerged. One interesting finding is that Grammar Translation is still used in EFL contexts, in larger classes, and with learners at low proficiency levels, though the ratio between the actual use of this method and teachers' preference does not match. Based on the results of the survey, a new theoretical framework is proposed to conceptualize language teaching methods in the post-methods era.

  2. Modern survey sampling

    CERN Document Server

    Chaudhuri, Arijit

    2014-01-01

    Exposure to SamplingAbstract Introduction Concepts of Population, Sample, and SamplingInitial RamificationsAbstract Introduction Sampling Design, Sampling SchemeRandom Numbers and Their Uses in Simple RandomSampling (SRS)Drawing Simple Random Samples with and withoutReplacementEstimation of Mean, Total, Ratio of Totals/Means:Variance and Variance EstimationDetermination of Sample SizesA.2 Appendix to Chapter 2 A.More on Equal Probability Sampling A.Horvitz-Thompson EstimatorA.SufficiencyA.LikelihoodA.Non-Existence Theorem More Intricacies Abstract Introduction Unequal Probability Sampling StrategiesPPS Sampling Exploring Improved WaysAbstract Introduction Stratified Sampling Cluster SamplingMulti-Stage SamplingMulti-Phase Sampling: Ratio and RegressionEstimationviiviii ContentsControlled SamplingModeling Introduction Super-Population ModelingPrediction Approach Model-Assisted Approach Bayesian Methods Spatial SmoothingSampling on Successive Occasions: Panel Rotation Non-Response and Not-at-Homes Weighting Adj...

  3. Studying Cannabis Use Behaviors With Facebook and Web Surveys: Methods and Insights.

    Science.gov (United States)

    Borodovsky, Jacob T; Marsch, Lisa A; Budney, Alan J

    2018-05-02

    The rapid and wide-reaching expansion of internet access and digital technologies offers epidemiologists numerous opportunities to study health behaviors. One particularly promising new data collection strategy is the use of Facebook's advertising platform in conjunction with Web-based surveys. Our research team at the Center for Technology and Behavioral Health has used this quick and cost-efficient method to recruit large samples and address unique scientific questions related to cannabis use. In conducting this research, we have gleaned several insights for using this sampling method effectively and have begun to document the characteristics of the resulting data. We believe this information could be useful to other researchers attempting to study cannabis use or, potentially, other health behaviors. The first aim of this paper is to describe case examples of procedures for using Facebook as a survey sampling method for studying cannabis use. We then present several distinctive features of the data produced using this method. Finally, we discuss the utility of this sampling method for addressing specific types of epidemiological research questions. Overall, we believe that sampling with Facebook advertisements and Web surveys is best conceptualized as a targeted, nonprobability-based method for oversampling cannabis users across the United States. ©Jacob T Borodovsky, Lisa A Marsch, Alan J Budney. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 02.05.2018.

  4. Inclusion of mobile phone numbers into an ongoing population health survey in New South Wales, Australia: design, methods, call outcomes, costs and sample representativeness.

    Science.gov (United States)

    Barr, Margo L; van Ritten, Jason J; Steel, David G; Thackway, Sarah V

    2012-11-22

    In Australia telephone surveys have been the method of choice for ongoing jurisdictional population health surveys. Although it was estimated in 2011 that nearly 20% of the Australian population were mobile-only phone users, the inclusion of mobile phone numbers into these existing landline population health surveys has not occurred. This paper describes the methods used for the inclusion of mobile phone numbers into an existing ongoing landline random digit dialling (RDD) health survey in an Australian state, the New South Wales Population Health Survey (NSWPHS). This paper also compares the call outcomes, costs and the representativeness of the resultant sample to that of the previous landline sample. After examining several mobile phone pilot studies conducted in Australia and possible sample designs (screening dual-frame and overlapping dual-frame), mobile phone numbers were included into the NSWPHS using an overlapping dual-frame design. Data collection was consistent, where possible, with the previous years' landline RDD phone surveys and between frames. Survey operational data for the frames were compared and combined. Demographic information from the interview data for mobile-only phone users, both, and total were compared to the landline frame using χ2 tests. Demographic information for each frame, landline and the mobile-only (equivalent to a screening dual frame design), and the frames combined (with appropriate overlap adjustment) were compared to the NSW demographic profile from the 2011 census using χ2 tests. In the first quarter of 2012, 3395 interviews were completed with 2171 respondents (63.9%) from the landline frame (17.6% landline only) and 1224 (36.1%) from the mobile frame (25.8% mobile only). Overall combined response, contact and cooperation rates were 33.1%, 65.1% and 72.2% respectively. As expected from previous research, the demographic profile of the mobile-only phone respondents differed most (more that were young, males, Aboriginal

  5. Dealing with trade-offs in destructive sampling designs for occupancy surveys.

    Directory of Open Access Journals (Sweden)

    Stefano Canessa

    Full Text Available Occupancy surveys should be designed to minimise false absences. This is commonly achieved by increasing replication or increasing the efficiency of surveys. In the case of destructive sampling designs, in which searches of individual microhabitats represent the repeat surveys, minimising false absences leads to an inherent trade-off. Surveyors can sample more low quality microhabitats, bearing the resultant financial costs and producing wider-spread impacts, or they can target high quality microhabitats were the focal species is more likely to be found and risk more severe impacts on local habitat quality. We show how this trade-off can be solved with a decision-theoretic approach, using the Millewa Skink Hemiergis millewae from southern Australia as a case study. Hemiergis millewae is an endangered reptile that is best detected using destructive sampling of grass hummocks. Within sites that were known to be occupied by H. millewae, logistic regression modelling revealed that lizards were more frequently detected in large hummocks. If this model is an accurate representation of the detection process, searching large hummocks is more efficient and requires less replication, but this strategy also entails destruction of the best microhabitats for the species. We developed an optimisation tool to calculate the minimum combination of the number and size of hummocks to search to achieve a given cumulative probability of detecting the species at a site, incorporating weights to reflect the sensitivity of the results to a surveyor's priorities. The optimisation showed that placing high weight on minimising volume necessitates impractical replication, whereas placing high weight on minimising replication requires searching very large hummocks which are less common and may be vital for H. millewae. While destructive sampling methods are sometimes necessary, surveyors must be conscious of the ecological impacts of these methods. This study provides a

  6. Evaluation of common methods for sampling invertebrate pollinator assemblages: net sampling out-perform pan traps.

    Science.gov (United States)

    Popic, Tony J; Davila, Yvonne C; Wardle, Glenda M

    2013-01-01

    Methods for sampling ecological assemblages strive to be efficient, repeatable, and representative. Unknowingly, common methods may be limited in terms of revealing species function and so of less value for comparative studies. The global decline in pollination services has stimulated surveys of flower-visiting invertebrates, using pan traps and net sampling. We explore the relative merits of these two methods in terms of species discovery, quantifying abundance, function, and composition, and responses of species to changing floral resources. Using a spatially-nested design we sampled across a 5000 km(2) area of arid grasslands, including 432 hours of net sampling and 1296 pan trap-days, between June 2010 and July 2011. Net sampling yielded 22% more species and 30% higher abundance than pan traps, and better reflected the spatio-temporal variation of floral resources. Species composition differed significantly between methods; from 436 total species, 25% were sampled by both methods, 50% only by nets, and the remaining 25% only by pans. Apart from being less comprehensive, if pan traps do not sample flower-visitors, the link to pollination is questionable. By contrast, net sampling functionally linked species to pollination through behavioural observations of flower-visitation interaction frequency. Netted specimens are also necessary for evidence of pollen transport. Benefits of net-based sampling outweighed minor differences in overall sampling effort. As pan traps and net sampling methods are not equivalent for sampling invertebrate-flower interactions, we recommend net sampling of invertebrate pollinator assemblages, especially if datasets are intended to document declines in pollination and guide measures to retain this important ecosystem service.

  7. Characterization of hazardous waste sites: a methods manual. Volume 2. Available sampling methods (second edition)

    International Nuclear Information System (INIS)

    Ford, P.J.; Turina, P.J.; Seely, D.E.

    1984-12-01

    Investigations at hazardous waste sites and sites of chemical spills often require on-site measurements and sampling activities to assess the type and extent of contamination. This document is a compilation of sampling methods and materials suitable to address most needs that arise during routine waste site and hazardous spill investigations. The sampling methods presented in this document are compiled by media, and were selected on the basis of practicality, economics, representativeness, compatability with analytical considerations, and safety, as well as other criteria. In addition to sampling procedures, sample handling and shipping, chain-of-custody procedures, instrument certification, equipment fabrication, and equipment decontamination procedures are described. Sampling methods for soil, sludges, sediments, and bulk materials cover the solids medium. Ten methods are detailed for surface waters, groundwater and containerized liquids; twelve are presented for ambient air, soil gases and vapors, and headspace gases. A brief discussion of ionizing radiation survey instruments is also provided

  8. Estimating sample size for a small-quadrat method of botanical ...

    African Journals Online (AJOL)

    Reports the results of a study conducted to determine an appropriate sample size for a small-quadrat method of botanical survey for application in the Mixed Bushveld of South Africa. Species density and grass density were measured using a small-quadrat method in eight plant communities in the Nylsvley Nature Reserve.

  9. Can Weighting Compensate for Sampling Issues in Internet Surveys?

    NARCIS (Netherlands)

    Vaske, J.J.; Jacobs, M.H.; Sijtsma, M.T.J.; Beaman, J.

    2011-01-01

    While Internet surveys have increased in popularity, results may not be representative of target populations. Weighting is commonly used to compensate for sampling issues. This article compared two surveys conducted in the Netherlands—a random mail survey (n = 353) and a convenience Internet survey

  10. Mobile acoustic transects miss rare bat species: implications of survey method and spatio-temporal sampling for monitoring bats

    Directory of Open Access Journals (Sweden)

    Elizabeth C. Braun de Torrez

    2017-11-01

    Full Text Available Due to increasing threats facing bats, long-term monitoring protocols are needed to inform conservation strategies. Effective monitoring should be easily repeatable while capturing spatio-temporal variation. Mobile acoustic driving transect surveys (‘mobile transects’ have been touted as a robust, cost-effective method to monitor bats; however, it is not clear how well mobile transects represent dynamic bat communities, especially when used as the sole survey approach. To assist biologists who must select a single survey method due to resource limitations, we assessed the effectiveness of three acoustic survey methods at detecting species richness in a vast protected area (Everglades National Park: (1 mobile transects, (2 stationary surveys that were strategically located by sources of open water and (3 stationary surveys that were replicated spatially across the landscape. We found that mobile transects underrepresented bat species richness compared to stationary surveys across all major vegetation communities and in two distinct seasons (dry/cool and wet/warm. Most critically, mobile transects failed to detect three rare bat species, one of which is federally endangered. Spatially replicated stationary surveys did not estimate higher species richness than strategically located stationary surveys, but increased the rate at which species were detected in one vegetation community. The survey strategy that detected maximum species richness and the highest mean nightly species richness with minimal effort was a strategically located stationary detector in each of two major vegetation communities during the wet/warm season.

  11. Mobile acoustic transects miss rare bat species: implications of survey method and spatio-temporal sampling for monitoring bats.

    Science.gov (United States)

    Braun de Torrez, Elizabeth C; Wallrichs, Megan A; Ober, Holly K; McCleery, Robert A

    2017-01-01

    Due to increasing threats facing bats, long-term monitoring protocols are needed to inform conservation strategies. Effective monitoring should be easily repeatable while capturing spatio-temporal variation. Mobile acoustic driving transect surveys ('mobile transects') have been touted as a robust, cost-effective method to monitor bats; however, it is not clear how well mobile transects represent dynamic bat communities, especially when used as the sole survey approach. To assist biologists who must select a single survey method due to resource limitations, we assessed the effectiveness of three acoustic survey methods at detecting species richness in a vast protected area (Everglades National Park): (1) mobile transects, (2) stationary surveys that were strategically located by sources of open water and (3) stationary surveys that were replicated spatially across the landscape. We found that mobile transects underrepresented bat species richness compared to stationary surveys across all major vegetation communities and in two distinct seasons (dry/cool and wet/warm). Most critically, mobile transects failed to detect three rare bat species, one of which is federally endangered. Spatially replicated stationary surveys did not estimate higher species richness than strategically located stationary surveys, but increased the rate at which species were detected in one vegetation community. The survey strategy that detected maximum species richness and the highest mean nightly species richness with minimal effort was a strategically located stationary detector in each of two major vegetation communities during the wet/warm season.

  12. Conducting a respondent-driven sampling survey with the use of existing resources in Sydney, Australia.

    Science.gov (United States)

    Paquette, Dana M; Bryant, Joanne; Crawford, Sione; de Wit, John B F

    2011-07-01

    Respondent-driven sampling (RDS) is a form of chain-referral sampling that is increasingly being used for HIV behavioural surveillance. When used for surveillance purposes, a sampling method should be relatively inexpensive and simple to operate. This study examined whether an RDS survey of people who inject drugs (PWID) in Sydney, Australia, could be successfully conducted through the use of minimal and existing resources. The RDS survey was conducted on the premises of a local needle and syringe program (NSP) with some adjustments to take into account the constraints of existing resources. The impact of the survey on clients and on staff was examined by summarizing NSP service data and by conducting post-survey discussions with NSP staff. From November 2009 till March 2010, 261 participants were recruited in 16 waves. A significant increase was found in the number of services provided by the NSP during and after data collection. Generally, staff felt that the survey had a positive impact by exposing a broader group of people to the NSP. However, conducting the survey may have led to privacy issues for NSP clients due to an increased number of people gathering around the NSP. This study shows that RDS can be conducted with the use of minimal and existing resources under certain conditions (e.g., use of a self-administered questionnaire and no biological samples taken). A more detailed cost-utility analysis is needed to determine whether RDS' advantages outweigh potential challenges when compared to simpler and less costly convenience methods. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  13. Coupling methods for multistage sampling

    OpenAIRE

    Chauvet, Guillaume

    2015-01-01

    Multistage sampling is commonly used for household surveys when there exists no sampling frame, or when the population is scattered over a wide area. Multistage sampling usually introduces a complex dependence in the selection of the final units, which makes asymptotic results quite difficult to prove. In this work, we consider multistage sampling with simple random without replacement sampling at the first stage, and with an arbitrary sampling design for further stages. We consider coupling ...

  14. Evaluation of common methods for sampling invertebrate pollinator assemblages: net sampling out-perform pan traps.

    Directory of Open Access Journals (Sweden)

    Tony J Popic

    Full Text Available Methods for sampling ecological assemblages strive to be efficient, repeatable, and representative. Unknowingly, common methods may be limited in terms of revealing species function and so of less value for comparative studies. The global decline in pollination services has stimulated surveys of flower-visiting invertebrates, using pan traps and net sampling. We explore the relative merits of these two methods in terms of species discovery, quantifying abundance, function, and composition, and responses of species to changing floral resources. Using a spatially-nested design we sampled across a 5000 km(2 area of arid grasslands, including 432 hours of net sampling and 1296 pan trap-days, between June 2010 and July 2011. Net sampling yielded 22% more species and 30% higher abundance than pan traps, and better reflected the spatio-temporal variation of floral resources. Species composition differed significantly between methods; from 436 total species, 25% were sampled by both methods, 50% only by nets, and the remaining 25% only by pans. Apart from being less comprehensive, if pan traps do not sample flower-visitors, the link to pollination is questionable. By contrast, net sampling functionally linked species to pollination through behavioural observations of flower-visitation interaction frequency. Netted specimens are also necessary for evidence of pollen transport. Benefits of net-based sampling outweighed minor differences in overall sampling effort. As pan traps and net sampling methods are not equivalent for sampling invertebrate-flower interactions, we recommend net sampling of invertebrate pollinator assemblages, especially if datasets are intended to document declines in pollination and guide measures to retain this important ecosystem service.

  15. Methods and representativeness of a European survey in children and adolescents: the KIDSCREEN study

    Directory of Open Access Journals (Sweden)

    von Rueden Ursula

    2007-07-01

    Full Text Available Abstract Background The objective of the present study was to compare three different sampling and questionnaire administration methods used in the international KIDSCREEN study in terms of participation, response rates, and external validity. Methods Children and adolescents aged 8–18 years were surveyed in 13 European countries using either telephone sampling and mail administration, random sampling of school listings followed by classroom or mail administration, or multistage random sampling of communities and households with self-administration of the survey materials at home. Cooperation, completion, and response rates were compared across countries and survey methods. Data on non-respondents was collected in 8 countries. The population fraction (PF, respondents in each sex-age, or educational level category, divided by the population in the same category from Eurostat census data and population fraction ratio (PFR, ratio of PF and their corresponding 95% confidence intervals were used to analyze differences by country between the KIDSCREEN samples and a reference Eurostat population. Results Response rates by country ranged from 18.9% to 91.2%. Response rates were highest in the school-based surveys (69.0%–91.2%. Sample proportions by age and gender were similar to the reference Eurostat population in most countries, although boys and adolescents were slightly underrepresented (PFR Conclusion School-based sampling achieved the highest overall response rates but also produced slightly more biased samples than the other methods. The results suggest that the samples were sufficiently representative to provide reference population values for the KIDSCREEN instrument.

  16. Understanding Sample Surveys: Selective Learning about Social Science Research Methods

    Science.gov (United States)

    Currin-Percival, Mary; Johnson, Martin

    2010-01-01

    We investigate differences in what students learn about survey methodology in a class on public opinion presented in two critically different ways: with the inclusion or exclusion of an original research project using a random-digit-dial telephone survey. Using a quasi-experimental design and data obtained from pretests and posttests in two public…

  17. Air sampling system for airborne surveys

    International Nuclear Information System (INIS)

    Jupiter, C.; Tipton, W.J.

    1975-01-01

    An air sampling system has been designed for installation on the Beechcraft King Air A-100 aircraft as a part of the Aerial Radiological Measuring System (ARMS). It is intended for both particle and whole gas sampling. The sampling probe is designed for isokinetic sampling and is mounted on a removable modified escape hatch cover, behind the co-pilot's seat, and extends about two feet forward of the hatch cover in the air stream lines. Directly behind the sampling probe inside the modified hatch cover is an expansion chamber, space for a 5-inch diameter filter paper cassette, and an optional four-stage cascade impactor for particle size distribution measurements. A pair of motors and blower pumps provide the necessary 0.5 atmosphere pressure across the type MSA 1106 B glass fiber filter paper to allow a flow rate of 50 cfm. The MSA 1106 B filter paper is designed to trap sub-micrometer particles with a high efficiency; it was chosen to enable a quantitative measurement of airborne radon daughters, one of the principal sources of background signals when radiological surveys are being performed. A venturi section and pressure gauges allow air flow rate measurements so that airborne contaminant concentrations may be quantified. A whole gas sampler capable of sampling a cubic meter of air is mounted inside the aircraft cabin. A nuclear counting system on board the aircraft provides capability for α, β and γ counting of filter paper samples. Design data are presented and types of survey missions which may be served by this system are described

  18. Sample size reduction in groundwater surveys via sparse data assimilation

    KAUST Repository

    Hussain, Z.; Muhammad, A.

    2013-01-01

    In this paper, we focus on sparse signal recovery methods for data assimilation in groundwater models. The objective of this work is to exploit the commonly understood spatial sparsity in hydrodynamic models and thereby reduce the number of measurements to image a dynamic groundwater profile. To achieve this we employ a Bayesian compressive sensing framework that lets us adaptively select the next measurement to reduce the estimation error. An extension to the Bayesian compressive sensing framework is also proposed which incorporates the additional model information to estimate system states from even lesser measurements. Instead of using cumulative imaging-like measurements, such as those used in standard compressive sensing, we use sparse binary matrices. This choice of measurements can be interpreted as randomly sampling only a small subset of dug wells at each time step, instead of sampling the entire grid. Therefore, this framework offers groundwater surveyors a significant reduction in surveying effort without compromising the quality of the survey. © 2013 IEEE.

  19. Sample size reduction in groundwater surveys via sparse data assimilation

    KAUST Repository

    Hussain, Z.

    2013-04-01

    In this paper, we focus on sparse signal recovery methods for data assimilation in groundwater models. The objective of this work is to exploit the commonly understood spatial sparsity in hydrodynamic models and thereby reduce the number of measurements to image a dynamic groundwater profile. To achieve this we employ a Bayesian compressive sensing framework that lets us adaptively select the next measurement to reduce the estimation error. An extension to the Bayesian compressive sensing framework is also proposed which incorporates the additional model information to estimate system states from even lesser measurements. Instead of using cumulative imaging-like measurements, such as those used in standard compressive sensing, we use sparse binary matrices. This choice of measurements can be interpreted as randomly sampling only a small subset of dug wells at each time step, instead of sampling the entire grid. Therefore, this framework offers groundwater surveyors a significant reduction in surveying effort without compromising the quality of the survey. © 2013 IEEE.

  20. Northern Marshall Islands radiological survey: sampling and analysis summary

    Energy Technology Data Exchange (ETDEWEB)

    Robison, W.L.; Conrado, C.L.; Eagle, R.J.; Stuart, M.L.

    1981-07-23

    A radiological survey was conducted in the Northern Marshall Islands to document reamining external gamma exposures from nuclear tests conducted at Enewetak and Bikini Atolls. An additional program was later included to obtain terrestrial and marine samples for radiological dose assessment for current or potential atoll inhabitants. This report is the first of a series summarizing the results from the terrestrial and marine surveys. The sample collection and processing procedures and the general survey methodology are discussed; a summary of the collected samples and radionuclide analyses is presented. Over 5400 samples were collected from the 12 atolls and 2 islands and prepared for analysis including 3093 soil, 961 vegetation, 153 animal, 965 fish composite samples (average of 30 fish per sample), 101 clam, 50 lagoon water, 15 cistern water, 17 groundwater, and 85 lagoon sediment samples. A complete breakdown by sample type, atoll, and island is given here. The total number of analyses by radionuclide are 8840 for /sup 241/Am, 6569 for /sup 137/Cs, 4535 for /sup 239 +240/Pu, 4431 for /sup 90/Sr, 1146 for /sup 238/Pu, 269 for /sup 241/Pu, and 114 each for /sup 239/Pu and /sup 240/Pu. A complete breakdown by sample category, atoll or island, and radionuclide is also included.

  1. Northern Marshall Islands radiological survey: sampling and analysis summary

    International Nuclear Information System (INIS)

    Robison, W.L.; Conrado, C.L.; Eagle, R.J.; Stuart, M.L.

    1981-01-01

    A radiological survey was conducted in the Northern Marshall Islands to document reamining external gamma exposures from nuclear tests conducted at Enewetak and Bikini Atolls. An additional program was later included to obtain terrestrial and marine samples for radiological dose assessment for current or potential atoll inhabitants. This report is the first of a series summarizing the results from the terrestrial and marine surveys. The sample collection and processing procedures and the general survey methodology are discussed; a summary of the collected samples and radionuclide analyses is presented. Over 5400 samples were collected from the 12 atolls and 2 islands and prepared for analysis including 3093 soil, 961 vegetation, 153 animal, 965 fish composite samples (average of 30 fish per sample), 101 clam, 50 lagoon water, 15 cistern water, 17 groundwater, and 85 lagoon sediment samples. A complete breakdown by sample type, atoll, and island is given here. The total number of analyses by radionuclide are 8840 for 241 Am, 6569 for 137 Cs, 4535 for 239+240 Pu, 4431 for 90 Sr, 1146 for 238 Pu, 269 for 241 Pu, and 114 each for 239 Pu and 240 Pu. A complete breakdown by sample category, atoll or island, and radionuclide is also included

  2. Non-response weighting adjustment approach in survey sampling ...

    African Journals Online (AJOL)

    Hence the discussion is illustrated with real examples from surveys (in particular 2003 KDHS) conducted by Central Bureau of Statistics (CBS) - Kenya. Some suggestions are made for improving the quality of non-response weighting. Keywords: Survey non-response; non-response adjustment factors; weighting; sampling ...

  3. A Unimodal Model for Double Observer Distance Sampling Surveys.

    Directory of Open Access Journals (Sweden)

    Earl F Becker

    Full Text Available Distance sampling is a widely used method to estimate animal population size. Most distance sampling models utilize a monotonically decreasing detection function such as a half-normal. Recent advances in distance sampling modeling allow for the incorporation of covariates into the distance model, and the elimination of the assumption of perfect detection at some fixed distance (usually the transect line with the use of double-observer models. The assumption of full observer independence in the double-observer model is problematic, but can be addressed by using the point independence assumption which assumes there is one distance, the apex of the detection function, where the 2 observers are assumed independent. Aerially collected distance sampling data can have a unimodal shape and have been successfully modeled with a gamma detection function. Covariates in gamma detection models cause the apex of detection to shift depending upon covariate levels, making this model incompatible with the point independence assumption when using double-observer data. This paper reports a unimodal detection model based on a two-piece normal distribution that allows covariates, has only one apex, and is consistent with the point independence assumption when double-observer data are utilized. An aerial line-transect survey of black bears in Alaska illustrate how this method can be applied.

  4. A Survey of Archaeological Samples Dated in 1985

    DEFF Research Database (Denmark)

    Mejdahl, Vagn

    1986-01-01

    A survey is given of archaeological samples received for dating in 1985 at the Nordic Laboratory for Thermoluminescence Dating. A total of 66 samples were dated, 42 of which were burnt stones. All results were corrected for short-term fading as measured for samples stored at room temperature...

  5. A Survey of Archaeological Samples Dated in 1984

    DEFF Research Database (Denmark)

    Mejdahl, Vagn

    A survey is given of archaeological samples dated in 1984 at the Nordic Laboratory for Thermoluminescence Dating. A total of 79 samples were dated, 49 of which were burnt stones. All results were corrected for fading as measured for samples stored for four weeks at room temperature. The alpha dose...

  6. The experience sampling method: Investigating students' affective experience

    Science.gov (United States)

    Nissen, Jayson M.; Stetzer, MacKenzie R.; Shemwell, Jonathan T.

    2013-01-01

    Improving non-cognitive outcomes such as attitudes, efficacy, and persistence in physics courses is an important goal of physics education. This investigation implemented an in-the-moment surveying technique called the Experience Sampling Method (ESM) [1] to measure students' affective experience in physics. Measurements included: self-efficacy, cognitive efficiency, activation, intrinsic motivation, and affect. Data are presented that show contrasts in students' experiences (e.g., in physics vs. non-physics courses).

  7. The Jamaica asthma and allergies national prevalence survey: rationale and methods

    Directory of Open Access Journals (Sweden)

    Edwards Nancy C

    2010-04-01

    Full Text Available Abstract Background Asthma is a significant public health problem in the Caribbean. Prevalence surveys using standardized measures of asthma provide valid prevalence estimates to facilitate regional and international comparisons and monitoring of trends. This paper describes methods used in the Jamaica Asthma and Allergies National Prevalence Survey, challenges associated with this survey and strategies used to overcome these challenges. Methods/Design An island wide, cross-sectional, community-based survey of asthma, asthma symptoms and allergies was done among adults and children using the European Community Respiratory Health Survey Questionnaire for adults and the International Study of Asthma and Allergies in Children. Stratified multi-stage cluster sampling was used to select 2, 163 adults aged 18 years and older and 2, 017 children aged 2-17 years for the survey. The Kish selection table was used to select one adult and one child per household. Data analysis accounted for sampling design and prevalence estimates were weighted to produce national estimates. Discussion The Jamaica Asthma and Allergies National Prevalence Survey is the first population- based survey in the Caribbean to determine the prevalence of asthma and allergies both in adults and children using standardized methods. With response rates exceeding 80% in both groups, this approach facilitated cost-effective gathering of high quality asthma prevalence data that will facilitate international and regional comparison and monitoring of asthma prevalence trends. Another unique feature of this study was the partnership with the Ministry of Health in Jamaica, which ensured the collection of data relevant for decision-making to facilitate the uptake of research evidence. The findings of this study will provide important data on the burden of asthma and allergies in Jamaica and contribute to evidence-informed planning of comprehensive asthma management and education programs.

  8. Satellite-aided survey sampling and implementation in low- and middle-income contexts: a low-cost/low-tech alternative.

    Science.gov (United States)

    Haenssgen, Marco J

    2015-01-01

    The increasing availability of online maps, satellite imagery, and digital technology can ease common constraints of survey sampling in low- and middle-income countries. However, existing approaches require specialised software and user skills, professional GPS equipment, and/or commercial data sources; they tend to neglect spatial sampling considerations when using satellite maps; and they continue to face implementation challenges analogous to conventional survey implementation methods. This paper presents an alternative way of utilising satellite maps and digital aides that aims to address these challenges. The case studies of two rural household surveys in Rajasthan (India) and Gansu (China) compare conventional survey sampling and implementation techniques with the use of online map services such as Google, Bing, and HERE maps. Modern yet basic digital technology can be integrated into the processes of preparing, implementing, and monitoring a rural household survey. Satellite-aided systematic random sampling enhanced the spatial representativeness of the village samples and entailed savings of approximately £4000 compared to conventional household listing, while reducing the duration of the main survey by at least 25 %. This low-cost/low-tech satellite-aided survey sampling approach can be useful for student researchers and resource-constrained research projects operating in low- and middle-income contexts with high survey implementation costs. While achieving transparent and efficient survey implementation at low costs, researchers aiming to adopt a similar process should be aware of the locational, technical, and logistical requirements as well as the methodological challenges of this strategy.

  9. Trypanosoma brucei gambiense trypanosomiasis in Terego county, northern Uganda, 1996: a lot quality assurance sampling survey.

    Science.gov (United States)

    Hutin, Yvan J F; Legros, Dominique; Owini, Vincent; Brown, Vincent; Lee, Evan; Mbulamberi, Dawson; Paquet, Christophe

    2004-04-01

    We estimated the pre-intervention prevalence of Trypanosoma brucei gambiense (Tbg) trypanosomiasis using the lot quality assurance sampling (LQAS) methods in 14 parishes of Terego County in northern Uganda. A total of 826 participants were included in the survey sample in 1996. The prevalence of laboratory confirmed Tbg trypanosomiasis adjusted for parish population sizes was 2.2% (95% confidence interval =1.1-3.2). This estimate was consistent with the 1.1% period prevalence calculated on the basis of cases identified through passive and active screening in 1996-1999. Ranking of parishes in four categories according to LQAS analysis of the 1996 survey predicted the prevalences observed during the first round of active screening in the population in 1997-1998 (P LQAS were validated by the results of the population screening, suggesting that these survey methods may be useful in the pre-intervention phase of sleeping sickness control programs.

  10. Assessing representativeness of sampling methods for reaching men who have sex with men: a direct comparison of results obtained from convenience and probability samples.

    Science.gov (United States)

    Schwarcz, Sandra; Spindler, Hilary; Scheer, Susan; Valleroy, Linda; Lansky, Amy

    2007-07-01

    Convenience samples are used to determine HIV-related behaviors among men who have sex with men (MSM) without measuring the extent to which the results are representative of the broader MSM population. We compared results from a cross-sectional survey of MSM recruited from gay bars between June and October 2001 to a random digit dial telephone survey conducted between June 2002 and January 2003. The men in the probability sample were older, better educated, and had higher incomes than men in the convenience sample, the convenience sample enrolled more employed men and men of color. Substance use around the time of sex was higher in the convenience sample but other sexual behaviors were similar. HIV testing was common among men in both samples. Periodic validation, through comparison of data collected by different sampling methods, may be useful when relying on survey data for program and policy development.

  11. Toward cost-efficient sampling methods

    Science.gov (United States)

    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. Brachytherapy dose-volume histogram computations using optimized stratified sampling methods

    International Nuclear Information System (INIS)

    Karouzakis, K.; Lahanas, M.; Milickovic, N.; Giannouli, S.; Baltas, D.; Zamboglou, N.

    2002-01-01

    A stratified sampling method for the efficient repeated computation of dose-volume histograms (DVHs) in brachytherapy is presented as used for anatomy based brachytherapy optimization methods. The aim of the method is to reduce the number of sampling points required for the calculation of DVHs for the body and the PTV. From the DVHs are derived the quantities such as Conformity Index COIN and COIN integrals. This is achieved by using partial uniform distributed sampling points with a density in each region obtained from a survey of the gradients or the variance of the dose distribution in these regions. The shape of the sampling regions is adapted to the patient anatomy and the shape and size of the implant. For the application of this method a single preprocessing step is necessary which requires only a few seconds. Ten clinical implants were used to study the appropriate number of sampling points, given a required accuracy for quantities such as cumulative DVHs, COIN indices and COIN integrals. We found that DVHs of very large tissue volumes surrounding the PTV, and also COIN distributions, can be obtained using a factor of 5-10 times smaller the number of sampling points in comparison with uniform distributed points

  13. A Survey of Blue-Noise Sampling and Its Applications

    KAUST Repository

    Yan, Dongming; Guo, Jian-Wei; Wang, Bin; Zhang, Xiao-Peng; Wonka, Peter

    2015-01-01

    In this paper, we survey recent approaches to blue-noise sampling and discuss their beneficial applications. We discuss the sampling algorithms that use points as sampling primitives and classify the sampling algorithms based on various aspects, e.g., the sampling domain and the type of algorithm. We demonstrate several well-known applications that can be improved by recent blue-noise sampling techniques, as well as some new applications such as dynamic sampling and blue-noise remeshing.

  14. A Survey of Blue-Noise Sampling and Its Applications

    KAUST Repository

    Yan, Dongming

    2015-05-05

    In this paper, we survey recent approaches to blue-noise sampling and discuss their beneficial applications. We discuss the sampling algorithms that use points as sampling primitives and classify the sampling algorithms based on various aspects, e.g., the sampling domain and the type of algorithm. We demonstrate several well-known applications that can be improved by recent blue-noise sampling techniques, as well as some new applications such as dynamic sampling and blue-noise remeshing.

  15. Using lot quality-assurance sampling and area sampling to identify priority areas for trachoma control: Viet Nam.

    Science.gov (United States)

    Myatt, Mark; Mai, Nguyen Phuong; Quynh, Nguyen Quang; Nga, Nguyen Huy; Tai, Ha Huy; Long, Nguyen Hung; Minh, Tran Hung; Limburg, Hans

    2005-10-01

    To report on the use of lot quality-assurance sampling (LQAS) surveys undertaken within an area-sampling framework to identify priority areas for intervention with trachoma control activities in Viet Nam. The LQAS survey method for the rapid assessment of the prevalence of active trachoma was adapted for use in Viet Nam with the aim of classifying individual communes by the prevalence of active trachoma among children in primary school. School-based sampling was used; school sites to be sampled were selected using an area-sampling approach. A total of 719 communes in 41 districts in 18 provinces were surveyed. Survey staff found the LQAS survey method both simple and rapid to use after initial problems with area-sampling methods were identified and remedied. The method yielded a finer spatial resolution of prevalence than had been previously achieved in Viet Nam using semiquantitative rapid assessment surveys and multistage cluster-sampled surveys. When used with area-sampling techniques, the LQAS survey method has the potential to form the basis of survey instruments that can be used to efficiently target resources for interventions against active trachoma. With additional work, such methods could provide a generally applicable tool for effective programme planning and for the certification of the elimination of trachoma as a blinding disease.

  16. Comparison of Health Examination Survey Methods in Brazil, Chile, Colombia, Mexico, England, Scotland, and the United States.

    Science.gov (United States)

    Mindell, Jennifer S; Moody, Alison; Vecino-Ortiz, Andres I; Alfaro, Tania; Frenz, Patricia; Scholes, Shaun; Gonzalez, Silvia A; Margozzini, Paula; de Oliveira, Cesar; Sanchez Romero, Luz Maria; Alvarado, Andres; Cabrera, Sebastián; Sarmiento, Olga L; Triana, Camilo A; Barquera, Simón

    2017-09-15

    Comparability of population surveys across countries is key to appraising trends in population health. Achieving this requires deep understanding of the methods used in these surveys to examine the extent to which the measurements are comparable. In this study, we obtained detailed protocols of 8 nationally representative surveys from 2007-2013 from Brazil, Chile, Colombia, Mexico, the United Kingdom (England and Scotland), and the United States-countries that that differ in economic and inequity indicators. Data were collected on sampling frame, sample selection procedures, recruitment, data collection methods, content of interview and examination modules, and measurement protocols. We also assessed their adherence to the World Health Organization's "STEPwise Approach to Surveillance" framework for population health surveys. The surveys, which included half a million participants, were highly comparable on sampling methodology, survey questions, and anthropometric measurements. Heterogeneity was found for physical activity questionnaires and biological samples collection. The common age range included by the surveys was adults aged 18-64 years. The methods used in these surveys were similar enough to enable comparative analyses of the data across the 7 countries. This comparability is crucial in assessing and comparing national and subgroup population health, and to assisting the transfer of research and policy knowledge across countries. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Towards Cost-efficient Sampling Methods

    OpenAIRE

    Peng, Luo; Yongli, Li; Chong, Wu

    2014-01-01

    The sampling method has been paid much attention in the field of complex network in general and statistical physics in particular. This paper presents two new sampling methods based on the perspective that a small part of vertices with high node degree can possess the most structure information of a network. The two proposed sampling methods are efficient in sampling the nodes with high degree. The first new sampling method is improved on the basis of the stratified random sampling method and...

  18. Geochemical drainage surveys for uranium: sampling and analytical methods based on trial surveys in Pennsylvania

    International Nuclear Information System (INIS)

    Rose, A.W.; Keith, M.L.; Suhr, N.H.

    1976-01-01

    Geochemical surveys near sandstone-type uranium prospects in northeastern and north-central Pennsylvania show that the deposits can be detected by carefully planned stream sediment surveys, but not by stream water surveys. Stream waters at single sites changed in U content by x10 to 50 during the 18 months of our studies, and even near known prospects, contain less than 0.2 ppB U most of the time. Uranium extractable from stream sediment by acetic acid--H 2 O 2 provides useful contrast between mineralized and nonmineralized drainages of a square mile or less; total U in sediment does not. High organic material results in increased U content of sediments and must be corrected. Changes in U content of sediment with time reach a maximum of x3 and appear to be of short duration. A sediment of about 200 mi 2 near Jim Thorpe detects anomalies extending over several square miles near known occurrences and a second anomaly about two miles northeast of Penn Haven Jct. A similar survey in Lycoming-Sullivan Counties shows anomalous zones near known prospects of the Beaver Lake area and northwest of Muncy Creek. As, Mn, Pb, and V are enriched in the mineralized zones, and perhaps in surrounding halo zones, but do not appear to be pathfinder elements useful for reconnaissance exploration

  19. A survey of archaeological samples dated in 1984

    International Nuclear Information System (INIS)

    Mejdahl, V.

    1985-10-01

    A survey is given of archaeological samples dated in 1984 at the Nordic Laboratory for Thermoluminescence Dating. A total of 79 samples were dated, 49 of which were burnt stones. All results were corrected for fading as measured for samples stored for four weeks at room temperature. The alpha dose contribution from uranium in the quartz and feldspar grains was included assuming an alpha efficiency facotr of 0.1 for quartz and 0.2 for feldspars. (author)

  20. National Survey on Access, Use and Promotion of Rational Use of Medicines (PNAUM: household survey component methods

    Directory of Open Access Journals (Sweden)

    Sotero Serrate Mengue

    Full Text Available ABSTRACT OBJECTIVE To describe methodological aspects of the household survey National Survey on Access, Use and Promotion of Rational Use of Medicines (PNAUM related to sampling design and implementation, the actual obtained sample, instruments and fieldwork. METHODS A cross-sectional, population-based study with probability sampling in three stages of the population living in households located in Brazilian urban areas. Fieldwork was carried out between September 2013 and February 2014. The data collection instrument included questions related to: information about households, residents and respondents; chronic diseases and medicines used; use of health services; acute diseases and events treated with drugs; use of contraceptives; use of pharmacy services; behaviors that may affect drug use; package inserts and packaging; lifestyle and health insurance. RESULTS In total, 41,433 interviews were carried out in 20,404 households and 576 urban clusters corresponding to 586 census tracts distributed in the five Brazilian regions, according to eight domains defined by age and gender. CONCLUSIONS The results of the survey may be used as a baseline for future studies aiming to assess the impact of government action on drug access and use. For local studies using a compatible method, PNAUM may serve as a reference point to evaluate variations in space and population. With a comprehensive evaluation of drug-related aspects, PNAUM is a major source of data for a variety of analyses to be carried out both at academic and government level.

  1. Combining Internet-Based and Postal Survey Methods in a Survey among Gynecologists: Results of a Randomized Trial.

    Science.gov (United States)

    Ernst, Sinja Alexandra; Brand, Tilman; Lhachimi, Stefan K; Zeeb, Hajo

    2018-04-01

    To assess whether a combination of Internet-based and postal survey methods (mixed-mode) compared to postal-only survey methods (postal-only) leads to improved response rates in a physician survey, and to compare the cost implications of the different recruitment strategies. All primary care gynecologists in Bremen and Lower Saxony, Germany, were invited to participate in a cross-sectional survey from January to July 2014. The sample was divided into two strata (A; B) depending on availability of an email address. Within each stratum, potential participants were randomly assigned to mixed-mode or postal-only group. In Stratum A, the mixed-mode group had a lower response rate compared to the postal-only group (12.5 vs. 20.2 percent; RR = 0.61, 95 percent CI: 0.44-0.87). In stratum B, no significant differences were found (15.6 vs. 16.2 percent; RR = 0.95, 95 percent CI: 0.62-1.44). Total costs (in €) per valid questionnaire returned (Stratum A: 399.72 vs. 248.85; Stratum B: 496.37 vs. 455.15) and per percentage point of response (Stratum A: 1,379.02 vs. 861.02; Stratum B 1,116.82 vs. 1,024.09) were higher, whereas variable costs were lower in mixed-mode compared to the respective postal-only groups (Stratum A cost ratio: 0.47, Stratum B cost ratio: 0.71). In this study, primary care gynecologists were more likely to participate by traditional postal-only than by mixed-mode survey methods that first offered an Internet option. However, the lower response rate for the mixed-mode method may be partly due to the older age structure of the responding gynecologists. Variable costs per returned questionnaire were substantially lower in mixed-mode groups and indicate the potential for cost savings if the sample population is sufficiently large. © Health Research and Educational Trust.

  2. Sampling methods

    International Nuclear Information System (INIS)

    Loughran, R.J.; Wallbrink, P.J.; Walling, D.E.; Appleby, P.G.

    2002-01-01

    Methods for the collection of soil samples to determine levels of 137 Cs and other fallout radionuclides, such as excess 210 Pb and 7 Be, will depend on the purposes (aims) of the project, site and soil characteristics, analytical capacity, the total number of samples that can be analysed and the sample mass required. The latter two will depend partly on detector type and capabilities. A variety of field methods have been developed for different field conditions and circumstances over the past twenty years, many of them inherited or adapted from soil science and sedimentology. The use of them inherited or adapted from soil science and sedimentology. The use of 137 Cs in erosion studies has been widely developed, while the application of fallout 210 Pb and 7 Be is still developing. Although it is possible to measure these nuclides simultaneously, it is common for experiments to designed around the use of 137 Cs along. Caesium studies typically involve comparison of the inventories found at eroded or sedimentation sites with that of a 'reference' site. An accurate characterization of the depth distribution of these fallout nuclides is often required in order to apply and/or calibrate the conversion models. However, depending on the tracer involved, the depth distribution, and thus the sampling resolution required to define it, differs. For example, a depth resolution of 1 cm is often adequate when using 137 Cs. However, fallout 210 Pb and 7 Be commonly has very strong surface maxima that decrease exponentially with depth, and fine depth increments are required at or close to the soil surface. Consequently, different depth incremental sampling methods are required when using different fallout radionuclides. Geomorphic investigations also frequently require determination of the depth-distribution of fallout nuclides on slopes and depositional sites as well as their total inventories

  3. Field Sample Preparation Method Development for Isotope Ratio Mass Spectrometry

    International Nuclear Information System (INIS)

    Leibman, C.; Weisbrod, K.; Yoshida, T.

    2015-01-01

    Non-proliferation and International Security (NA-241) established a working group of researchers from Los Alamos National Laboratory (LANL), Pacific Northwest National Laboratory (PNNL) and Savannah River National Laboratory (SRNL) to evaluate the utilization of in-field mass spectrometry for safeguards applications. The survey of commercial off-the-shelf (COTS) mass spectrometers (MS) revealed no instrumentation existed capable of meeting all the potential safeguards requirements for performance, portability, and ease of use. Additionally, fieldable instruments are unlikely to meet the International Target Values (ITVs) for accuracy and precision for isotope ratio measurements achieved with laboratory methods. The major gaps identified for in-field actinide isotope ratio analysis were in the areas of: 1. sample preparation and/or sample introduction, 2. size reduction of mass analyzers and ionization sources, 3. system automation, and 4. decreased system cost. Development work in 2 through 4, numerated above continues, in the private and public sector. LANL is focusing on developing sample preparation/sample introduction methods for use with the different sample types anticipated for safeguard applications. Addressing sample handling and sample preparation methods for MS analysis will enable use of new MS instrumentation as it becomes commercially available. As one example, we have developed a rapid, sample preparation method for dissolution of uranium and plutonium oxides using ammonium bifluoride (ABF). ABF is a significantly safer and faster alternative to digestion with boiling combinations of highly concentrated mineral acids. Actinides digested with ABF yield fluorides, which can then be analyzed directly or chemically converted and separated using established column chromatography techniques as needed prior to isotope analysis. The reagent volumes and the sample processing steps associated with ABF sample digestion lend themselves to automation and field

  4. A two-phase sampling survey for nonresponse and its paradata to correct nonresponse bias in a health surveillance survey.

    Science.gov (United States)

    Santin, G; Bénézet, L; Geoffroy-Perez, B; Bouyer, J; Guéguen, A

    2017-02-01

    The decline in participation rates in surveys, including epidemiological surveillance surveys, has become a real concern since it may increase nonresponse bias. The aim of this study is to estimate the contribution of a complementary survey among a subsample of nonrespondents, and the additional contribution of paradata in correcting for nonresponse bias in an occupational health surveillance survey. In 2010, 10,000 workers were randomly selected and sent a postal questionnaire. Sociodemographic data were available for the whole sample. After data collection of the questionnaires, a complementary survey among a random subsample of 500 nonrespondents was performed using a questionnaire administered by an interviewer. Paradata were collected for the complete subsample of the complementary survey. Nonresponse bias in the initial sample and in the combined samples were assessed using variables from administrative databases available for the whole sample, not subject to differential measurement errors. Corrected prevalences by reweighting technique were estimated by first using the initial survey alone and then the initial and complementary surveys combined, under several assumptions regarding the missing data process. Results were compared by computing relative errors. The response rates of the initial and complementary surveys were 23.6% and 62.6%, respectively. For the initial and the combined surveys, the relative errors decreased after correction for nonresponse on sociodemographic variables. For the combined surveys without paradata, relative errors decreased compared with the initial survey. The contribution of the paradata was weak. When a complex descriptive survey has a low response rate, a short complementary survey among nonrespondents with a protocol which aims to maximize the response rates, is useful. The contribution of sociodemographic variables in correcting for nonresponse bias is important whereas the additional contribution of paradata in

  5. Sample Archaeological Survey of Public Use Areas, Milford Lake, Kansas

    Science.gov (United States)

    1982-09-01

    especially ceramics); Middle "" Mississippian, Middle Woodland and Central Plains archaeology ; the engineering and building technology of the Maya ...Sample Archaeological Survey of Public Use Areas -- 0C 0 awo (L" . .614 4.- -. 1?CNOV 1 40484 * , "n. O ji - 0" By Laura S. Schwiekhard Thn ’.iint haUs...RECIPIENT’S CATALOG NUMBER 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED Milford Lake, Kansas Sample Archaeological Survey of Public Use

  6. Survey: interpolation methods for whole slide image processing.

    Science.gov (United States)

    Roszkowiak, L; Korzynska, A; Zak, J; Pijanowska, D; Swiderska-Chadaj, Z; Markiewicz, T

    2017-02-01

    Evaluating whole slide images of histological and cytological samples is used in pathology for diagnostics, grading and prognosis . It is often necessary to rescale whole slide images of a very large size. Image resizing is one of the most common applications of interpolation. We collect the advantages and drawbacks of nine interpolation methods, and as a result of our analysis, we try to select one interpolation method as the preferred solution. To compare the performance of interpolation methods, test images were scaled and then rescaled to the original size using the same algorithm. The modified image was compared to the original image in various aspects. The time needed for calculations and results of quantification performance on modified images were also compared. For evaluation purposes, we used four general test images and 12 specialized biological immunohistochemically stained tissue sample images. The purpose of this survey is to determine which method of interpolation is the best to resize whole slide images, so they can be further processed using quantification methods. As a result, the interpolation method has to be selected depending on the task involving whole slide images. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

  7. Comparison of Satellite Surveying to Traditional Surveying Methods for the Resources Industry

    Science.gov (United States)

    Osborne, B. P.; Osborne, V. J.; Kruger, M. L.

    Modern ground-based survey methods involve detailed survey, which provides three-space co-ordinates for surveyed points, to a high level of accuracy. The instruments are operated by surveyors, who process the raw results to create survey location maps for the subject of the survey. Such surveys are conducted for a location or region and referenced to the earth global co- ordinate system with global positioning system (GPS) positioning. Due to this referencing the survey is only as accurate as the GPS reference system. Satellite survey remote sensing utilise satellite imagery which have been processed using commercial geographic information system software. Three-space co-ordinate maps are generated, with an accuracy determined by the datum position accuracy and optical resolution of the satellite platform.This paper presents a case study, which compares topographic surveying undertaken by traditional survey methods with satellite surveying, for the same location. The purpose of this study is to assess the viability of satellite remote sensing for surveying in the resources industry. The case study involves a topographic survey of a dune field for a prospective mining project area in Pakistan. This site has been surveyed using modern surveying techniques and the results are compared to a satellite survey performed on the same area.Analysis of the results from traditional survey and from the satellite survey involved a comparison of the derived spatial co- ordinates from each method. In addition, comparisons have been made of costs and turnaround time for both methods.The results of this application of remote sensing is of particular interest for survey in areas with remote and extreme environments, weather extremes, political unrest, poor travel links, which are commonly associated with mining projects. Such areas frequently suffer language barriers, poor onsite technical support and resources.

  8. Methods of the National Nutrition Survey 1999 Metodología de la Encuesta Nacional de Nutrición 1999

    OpenAIRE

    Elsa Resano-Pérez; Ignacio Méndez-Ramírez; Teresa Shamah-Levy; Juan A Rivera; Jaime Sepúlveda-Amor

    2003-01-01

    OBJECTIVE: To describe the methods and analyses of the 1999 National Nutrition Survey (NNS-99). MATERIAL AND METHODS: The 1999 National Nutrition Survey (NNS-99) is a probabilistic survey with nationwide representativity. The NNS-99 included four regions and urban and rural areas of Mexico. The last sampling units were households, selected through stratified cluster sampling. The study population consisted of children under five years of age, school-age children (6-11 years), and women of chi...

  9. Comparisons of methods for generating conditional Poisson samples and Sampford samples

    OpenAIRE

    Grafström, Anton

    2005-01-01

    Methods for conditional Poisson sampling (CP-sampling) and Sampford sampling are compared and the focus is on the efficiency of the methods. The efficiency is investigated by simulation in different sampling situations. It was of interest to compare methods since new methods for both CP-sampling and Sampford sampling were introduced by Bondesson, Traat & Lundqvist in 2004. The new methods are acceptance rejection methods that use the efficient Pareto sampling method. They are found to be ...

  10. A survey of archaeological samples dated in 1987

    International Nuclear Information System (INIS)

    Mejdahl, V.

    1988-10-01

    A survey is given of archaeological samples dated in 1987 at the Nordic Laboratory for Thermoluminescence Dating. A total of 74 samples were dated. The results were corrected for short-term fading of feldspars as measured for samples stored at room temperature for four weeks or at 100 deg. C for two weeks. The beta dose from potassium and rubidium in feldspar, and the alpha dose from uranium and thorium in quartz and feldspar were included, assuming alpha efficiency factors of 0.1 for quartz and 0.2 for feldspar. (author) 20 tabs., 29 refs

  11. A survey of archaeological samples dated in 1985

    International Nuclear Information System (INIS)

    Mejdahl, V.

    1986-11-01

    A survey is given of archaeological samples received for dating in 1985 at the Nordic Laboratory for Thermoluminescence Dating. A total of 66 samples were dated, 42 of which were burnt stones. All results were corrected for short- term fading as measured for samples stored at room temperature for four weeks. The beta dose from potassium and rubidium in feldspar and the alpha dose from uranium and thorium in quarts and feldspar were included assuming alpha efficiency factors of 0.1 for quartz and 0.2 for feldspar. (author)

  12. A survey of archaeological samples dated in 1986

    International Nuclear Information System (INIS)

    Mejdahl, V.

    1987-10-01

    A survey is given of archaeological samples dated in 1986 at the Nordic Laboratory for Thermoluminescence Dating. A total of 56 samples were dated. The results were corrected for shortterm fading measured for samples stored for four weeks at room temperature or at 100 deg. C. The beta dose from potassium and rubidium in feldspar and the alpha dose from uranium and thorium in quartz and feldspar grain were included assuming alpha efficiency factors of 0.1 and 0.2 for quartz and feldspar, respectively. 21 refs. (author)

  13. A Novel Analysis Method for Paired-Sample Microbial Ecology Experiments.

    Science.gov (United States)

    Olesen, Scott W; Vora, Suhani; Techtmann, Stephen M; Fortney, Julian L; Bastidas-Oyanedel, Juan R; Rodríguez, Jorge; Hazen, Terry C; Alm, Eric J

    2016-01-01

    Many microbial ecology experiments use sequencing data to measure a community's response to an experimental treatment. In a common experimental design, two units, one control and one experimental, are sampled before and after the treatment is applied to the experimental unit. The four resulting samples contain information about the dynamics of organisms that respond to the treatment, but there are no analytical methods designed to extract exactly this type of information from this configuration of samples. Here we present an analytical method specifically designed to visualize and generate hypotheses about microbial community dynamics in experiments that have paired samples and few or no replicates. The method is based on the Poisson lognormal distribution, long studied in macroecology, which we found accurately models the abundance distribution of taxa counts from 16S rRNA surveys. To demonstrate the method's validity and potential, we analyzed an experiment that measured the effect of crude oil on ocean microbial communities in microcosm. Our method identified known oil degraders as well as two clades, Maricurvus and Rhodobacteraceae, that responded to amendment with oil but do not include known oil degraders. Our approach is sensitive to organisms that increased in abundance only in the experimental unit but less sensitive to organisms that increased in both control and experimental units, thus mitigating the role of "bottle effects".

  14. Pairing field methods to improve inference in wildlife surveys while accommodating detection covariance.

    Science.gov (United States)

    Clare, John; McKinney, Shawn T; DePue, John E; Loftin, Cynthia S

    2017-10-01

    It is common to use multiple field sampling methods when implementing wildlife surveys to compare method efficacy or cost efficiency, integrate distinct pieces of information provided by separate methods, or evaluate method-specific biases and misclassification error. Existing models that combine information from multiple field methods or sampling devices permit rigorous comparison of method-specific detection parameters, enable estimation of additional parameters such as false-positive detection probability, and improve occurrence or abundance estimates, but with the assumption that the separate sampling methods produce detections independently of one another. This assumption is tenuous if methods are paired or deployed in close proximity simultaneously, a common practice that reduces the additional effort required to implement multiple methods and reduces the risk that differences between method-specific detection parameters are confounded by other environmental factors. We develop occupancy and spatial capture-recapture models that permit covariance between the detections produced by different methods, use simulation to compare estimator performance of the new models to models assuming independence, and provide an empirical application based on American marten (Martes americana) surveys using paired remote cameras, hair catches, and snow tracking. Simulation results indicate existing models that assume that methods independently detect organisms produce biased parameter estimates and substantially understate estimate uncertainty when this assumption is violated, while our reformulated models are robust to either methodological independence or covariance. Empirical results suggested that remote cameras and snow tracking had comparable probability of detecting present martens, but that snow tracking also produced false-positive marten detections that could potentially substantially bias distribution estimates if not corrected for. Remote cameras detected marten

  15. Y-STR frequency surveying method

    DEFF Research Database (Denmark)

    Willuweit, Sascha; Caliebe, Amke; Andersen, Mikkel Meyer

    2011-01-01

    Reasonable formalized methods to estimate the frequencies of DNA profiles generated from lineage markers have been proposed in the past years and were discussed in the forensic community. Recently, collections of population data on the frequencies of variations in Y chromosomal STR profiles have...... reached a new quality with the establishment of the comprehensive neatly quality-controlled reference database YHRD. Grounded on such unrivalled empirical material from hundreds of populations studies the core assumption of the Haplotype Frequency Surveying Method originally described 10 years ago can...... be tested and improved. Here we provide new approaches to calculate the parameters used in the frequency surveying method: a maximum likelihood estimation of the regression parameters (r1, r2, s1 and s2) and a revised Frequency Surveying framework with variable binning and a database preprocessing to take...

  16. Acceptability of self-collection sampling for HPV-DNA testing in low-resource settings: a mixed methods approach.

    Science.gov (United States)

    Bansil, Pooja; Wittet, Scott; Lim, Jeanette L; Winkler, Jennifer L; Paul, Proma; Jeronimo, Jose

    2014-06-12

    Vaginal self-sampling with HPV-DNA tests is a promising primary screening method for cervical cancer. However, women's experiences, concerns and the acceptability of such tests in low-resource settings remain unknown. In India, Nicaragua, and Uganda, a mixed-method design was used to collect data from surveys (N = 3,863), qualitative interviews (N = 72; 20 providers and 52 women) and focus groups (N = 30 women) on women's and providers' experiences with self-sampling, women's opinions of sampling at home, and their future needs. Among surveyed women, 90% provided a self- collected sample. Of these, 75% reported it was easy, although 52% were initially concerned about hurting themselves and 24% were worried about not getting a good sample. Most surveyed women preferred self-sampling (78%). However it was not clear if they responded to the privacy of self-sampling or the convenience of avoiding a pelvic examination, or both. In follow-up interviews, most women reported that they didn't mind self-sampling, but many preferred to have a provider collect the vaginal sample. Most women also preferred clinic-based screening (as opposed to home-based self-sampling), because the sample could be collected by a provider, women could receive treatment if needed, and the clinic was sanitary and provided privacy. Self-sampling acceptability was higher when providers prepared women through education, allowed women to examine the collection brush, and were present during the self-collection process. Among survey respondents, aids that would facilitate self-sampling in the future were: staff help (53%), additional images in the illustrated instructions (31%), and a chance to practice beforehand with a doll/model (26%). Self-and vaginal-sampling are widely acceptable among women in low-resource settings. Providers have a unique opportunity to educate and prepare women for self-sampling and be flexible in accommodating women's preference for self-sampling.

  17. A survey of archaeological samples dated in 1988

    International Nuclear Information System (INIS)

    Mejdahl, V.

    1989-08-01

    A survey is given of archaeological samples dated in 1988 at the Nordic Laboratory for Thermoluminescence Dating. A total of 67 samples were dated. The results were corrected for short-term fading of feldspars as measured for samples stored at room temperature for four weeks or at 100 deg. C for two weeks. The beta dose from potassium and rubidium in feldspar, and the alpha dose from uranium and thorium in quartz and feldspar were included assuming alpha efficiency factors of 0.1 for quartz and 0.2 for feldspar. (author) 22 tabs., 1 ill., 14 refs

  18. National Sample Survey of Registered Nurses II. Status of Nurses: November 1980.

    Science.gov (United States)

    Bentley, Barbara S.; And Others

    This report provides data describing the nursing population as determined by the second national sample survey of registered nurses. A brief introduction is followed by a chapter that presents an overview of the survey methodology, including details on the sampling design, the response rate, and the statistical reliability. Chapter 3 provides a…

  19. A survey of archaeological and geological samples dated in 1990

    International Nuclear Information System (INIS)

    Mejdahl, V.

    1991-01-01

    A survey of dated archaeological and geological samples is given, using thermoluminescence dating. Some of the sediment samples were also dated by means of optically stimulated luminescence (OSL) using a newly developed infrared diode system. In most cases the luminescence dates are in accordance with archaeological and geological estimates. Some discrepancies were found because some feldspar samples exhibited severe anomalous fading. It may be possible to avoid this problem by basing the dating on OSL of quartz. For sediment samples of Eemian or Early Weichselian age severe underestimates were encountered with both methods. The reason might be related to the large difference between the natural dose rate and that used in laboratory irradiations. Traps corresponding to low-temperature peaks such as the 150 deg. C peak in feldspars will remain almost empty under natural conditions, but will fill up to saturation under laboratory irradiation and thereby more charges will be captured in high-temperature traps. As a result, natural growth curves and laboratory produced luminescence growth curves will have different slopes and this will lead to underestimation. This problem might avoided by holding samples at an elevated temperature during laboratory irradiation, thus keeping the low-temperature traps empty. Preliminary experiments where feldspar samples were held at 130 deg. C during irradiation have given promising results. (AB) (31 refs.)

  20. Novel platform for ocean survey and autonomous sampling using multi-agent system

    OpenAIRE

    Taher, Tawfiq; Weymouth, G.D.; Varghese, Tony

    2013-01-01

    In-situ surveying and sampling of ocean environments provides critical data for laboratory work and oceanographic research. However, sampling a time-varying ocean field is often time and resource limited-meaning that samples often miss the features of interest. This paper presents a modular autonomous multi-agent robotic system which has been developed to accommodate a variety of research activities. This paper demonstrates the complementary capabilities of the agents by simultaneously survey...

  1. Can smartphones measure momentary quality of life and participation? A proof of concept using experience sampling surveys with university students.

    Science.gov (United States)

    Liddle, Jacki; Wishink, Anna; Springfield, Liz; Gustafsson, Louise; Ireland, David; Silburn, Peter

    2017-08-01

    Understanding quality of life and participation is a key aspect of occupational therapy research. The use of smartphones to deliver experience-sampling surveys may provide an accessible way to monitor these outcomes. This study used smartphone-based experience sampling methods (ESM) to investigate factors influencing momentary quality of life (mQOL) of university students. A convenience sample of students at an Australian university participated. Using a custom smartphone application, ESM surveys were sent six to eight times, every second day, over a week. Participants indicated their mQOL, occupational participation, occupational enjoyment, social context and location via surveys and provided demographic and health information in a single self-report questionnaire. The relationship between mQOL and variables was analysed at the survey level using logistic regression. Forty students completed 391 surveys. Higher mQOL was significantly related to participation in productive occupations (z = 3.48; P = 0.001), moderate (z = 4.00; P sample, analysing at the individual level, and using ESM in conjunction with other methodologies is recommended. © 2017 Occupational Therapy Australia.

  2. Optimum strata boundaries and sample sizes in health surveys using auxiliary variables.

    Science.gov (United States)

    Reddy, Karuna Garan; Khan, Mohammad G M; Khan, Sabiha

    2018-01-01

    Using convenient stratification criteria such as geographical regions or other natural conditions like age, gender, etc., is not beneficial in order to maximize the precision of the estimates of variables of interest. Thus, one has to look for an efficient stratification design to divide the whole population into homogeneous strata that achieves higher precision in the estimation. In this paper, a procedure for determining Optimum Stratum Boundaries (OSB) and Optimum Sample Sizes (OSS) for each stratum of a variable of interest in health surveys is developed. The determination of OSB and OSS based on the study variable is not feasible in practice since the study variable is not available prior to the survey. Since many variables in health surveys are generally skewed, the proposed technique considers the readily-available auxiliary variables to determine the OSB and OSS. This stratification problem is formulated into a Mathematical Programming Problem (MPP) that seeks minimization of the variance of the estimated population parameter under Neyman allocation. It is then solved for the OSB by using a dynamic programming (DP) technique. A numerical example with a real data set of a population, aiming to estimate the Haemoglobin content in women in a national Iron Deficiency Anaemia survey, is presented to illustrate the procedure developed in this paper. Upon comparisons with other methods available in literature, results reveal that the proposed approach yields a substantial gain in efficiency over the other methods. A simulation study also reveals similar results.

  3. Mobile phones are a viable option for surveying young Australian women: a comparison of two telephone survey methods

    Directory of Open Access Journals (Sweden)

    Liu Bette

    2011-11-01

    Full Text Available Abstract Background Households with fixed-line telephones have decreased while mobile (cell phone ownership has increased. We therefore sought to examine the feasibility of recruiting young women for a national health survey through random digit dialling mobile phones. Methods Two samples of women aged 18 to 39 years were surveyed by random digit dialling fixed and mobile numbers. We compared participation rates and responses to a questionnaire between women surveyed by each contact method. Results After dialling 5,390 fixed-lines and 3,697 mobile numbers, 140 and 128 women were recruited respectively. Among women contacted and found to be eligible, participation rates were 74% for fixed-lines and 88% for mobiles. Taking into account calls to numbers where eligibility was unknown (e.g. unanswered calls the estimated response rates were 54% and 45% respectively. Of women contacted by fixed-line, 97% reported having a mobile while 61% of those contacted by mobile reported having a fixed-line at home. After adjusting for age, there were no significant differences between mobile-only and fixed-line responders with respect to education, residence, and various health behaviours; however compared to those with fixed-lines, mobile-only women were more likely to identify as Indigenous (OR 4.99, 95%CI 1.52-16.34 and less likely to live at home with their parents (OR 0.09, 95%CI 0.03-0.29. Conclusions Random digit dialling mobile phones to conduct a health survey in young Australian women is feasible, gives a comparable response rate and a more representative sample than dialling fixed-lines only. Telephone surveys of young women should include mobile dialling.

  4. The economic impact of poor sample quality in clinical chemistry laboratories: results from a global survey.

    Science.gov (United States)

    Erdal, Erik P; Mitra, Debanjali; Khangulov, Victor S; Church, Stephen; Plokhoy, Elizabeth

    2017-03-01

    Background Despite advances in clinical chemistry testing, poor blood sample quality continues to impact laboratory operations and the quality of results. While previous studies have identified the preanalytical causes of lower sample quality, few studies have examined the economic impact of poor sample quality on the laboratory. Specifically, the costs associated with workarounds related to fibrin and gel contaminants remain largely unexplored. Methods A quantitative survey of clinical chemistry laboratory stakeholders across 10 international regions, including countries in North America, Europe and Oceania, was conducted to examine current blood sample testing practices, sample quality issues and practices to remediate poor sample quality. Survey data were used to estimate costs incurred by laboratories to mitigate sample quality issues. Results Responses from 164 participants were included in the analysis, which was focused on three specific issues: fibrin strands, fibrin masses and gel globules. Fibrin strands were the most commonly reported issue, with an overall incidence rate of ∼3%. Further, 65% of respondents indicated that these issues contribute to analyzer probe clogging, and the majority of laboratories had visual inspection and manual remediation practices in place to address fibrin- and gel-related quality problems (55% and 70%, respectively). Probe maintenance/replacement, visual inspection and manual remediation were estimated to carry significant costs for the laboratories surveyed. Annual cost associated with lower sample quality and remediation related to fibrin and/or gel globules for an average US laboratory was estimated to be $100,247. Conclusions Measures to improve blood sample quality present an important step towards improved laboratory operations.

  5. Terrestrial gamma radiation baseline mapping using ultra low density sampling methods

    International Nuclear Information System (INIS)

    Kleinschmidt, R.; Watson, D.

    2016-01-01

    Baseline terrestrial gamma radiation maps are indispensable for providing basic reference information that may be used in assessing the impact of a radiation related incident, performing epidemiological studies, remediating land contaminated with radioactive materials, assessment of land use applications and resource prospectivity. For a large land mass, such as Queensland, Australia (over 1.7 million km 2 ), it is prohibitively expensive and practically difficult to undertake detailed in-situ radiometric surveys of this scale. It is proposed that an existing, ultra-low density sampling program already undertaken for the purpose of a nationwide soil survey project be utilised to develop a baseline terrestrial gamma radiation map. Geoelement data derived from the National Geochemistry Survey of Australia (NGSA) was used to construct a baseline terrestrial gamma air kerma rate map, delineated by major drainage catchments, for Queensland. Three drainage catchments (sampled at the catchment outlet) spanning low, medium and high radioelement concentrations were selected for validation of the methodology using radiometric techniques including in-situ measurements and soil sampling for high resolution gamma spectrometry, and comparative non-radiometric analysis. A Queensland mean terrestrial air kerma rate, as calculated from the NGSA outlet sediment uranium, thorium and potassium concentrations, of 49 ± 69 nGy h −1 (n = 311, 3σ 99% confidence level) is proposed as being suitable for use as a generic terrestrial air kerma rate background range. Validation results indicate that catchment outlet measurements are representative of the range of results obtained across the catchment and that the NGSA geoelement data is suitable for calculation and mapping of terrestrial air kerma rate. - Highlights: • A baseline terrestrial air kerma map of Queensland, Australia was developed using geochemical data from a major drainage catchment ultra-low density sampling program

  6. Metal speciation: survey of environmental methods of analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mach, M.H.; Nott, B.; Scott, J.W.; Maddalone, R.F.; Whiddon, N.T. [TRW, Redondo Beach, CA (United States). Chemistry Technology Dept.

    1996-07-01

    As part of a recent task under the EPRI Analytical Methods Qualification Program (RP 1851), TRW has surveyed the methods available for monitoring metal species in typical utility aqueous discharge streams. Methods for determining the individual species of these metals can become important in a regulatory sense as the EPA transitions to assessment of environmental risk based on bioavailability. For example, EPA considers methyl mercury and Cr(VI) much more toxic to the aquatic environment than inorganic mercury or Cr(III). The species of a given element can also differ in their transport and bioaccumulation. Methods for speciation generally include a selective separation step followed by standard metals analysis. Speciation, therefore, is mainly derived from the separation step and not from the method of final quantisation. Examples of separation/analysis include: selective extraction followed by graphite furnace atomic absorption or ICP-MS; separation by GC followed by metals detection; chelation and/or direct separation by LC followed by UV measurement or metals detection; and ion chromatography with conductivity, UV, or metals detection. There are a number of sampling issues associated with metal species such as stabilization (maintaining oxidation state), absorption, and filtration that need to be addressed in order to obtain and maintain a representative sample for analysis. 45 refs., 1 tab.

  7. Pairing call-response surveys and distance sampling for a mammalian carnivore

    Science.gov (United States)

    Hansen, Sara J. K.; Frair, Jacqueline L.; Underwood, Harold B.; Gibbs, James P.

    2015-01-01

    Density estimates accounting for differential animal detectability are difficult to acquire for wide-ranging and elusive species such as mammalian carnivores. Pairing distance sampling with call-response surveys may provide an efficient means of tracking changes in populations of coyotes (Canis latrans), a species of particular interest in the eastern United States. Blind field trials in rural New York State indicated 119-m linear error for triangulated coyote calls, and a 1.8-km distance threshold for call detectability, which was sufficient to estimate a detection function with precision using distance sampling. We conducted statewide road-based surveys with sampling locations spaced ≥6 km apart from June to August 2010. Each detected call (be it a single or group) counted as a single object, representing 1 territorial pair, because of uncertainty in the number of vocalizing animals. From 524 survey points and 75 detections, we estimated the probability of detecting a calling coyote to be 0.17 ± 0.02 SE, yielding a detection-corrected index of 0.75 pairs/10 km2 (95% CI: 0.52–1.1, 18.5% CV) for a minimum of 8,133 pairs across rural New York State. Importantly, we consider this an index rather than true estimate of abundance given the unknown probability of coyote availability for detection during our surveys. Even so, pairing distance sampling with call-response surveys provided a novel, efficient, and noninvasive means of monitoring populations of wide-ranging and elusive, albeit reliably vocal, mammalian carnivores. Our approach offers an effective new means of tracking species like coyotes, one that is readily extendable to other species and geographic extents, provided key assumptions of distance sampling are met.

  8. Nationwide survey of policies and practices related to capillary blood sampling in medical laboratories in Croatia

    OpenAIRE

    Lenicek Krleza, Jasna

    2014-01-01

    Introduction: Capillary sampling is increasingly used to obtain blood for laboratory tests in volumes as small as necessary and as non-invasively as possible. Whether capillary blood sampling is also frequent in Croatia, and whether it is performed according to international laboratory standards is unclear. Materials and methods: All medical laboratories that participate in the Croatian National External Quality Assessment Program (N = 204) were surveyed on-line to collect information about t...

  9. Distance sampling methods and applications

    CERN Document Server

    Buckland, S T; Marques, T A; Oedekoven, C S

    2015-01-01

    In this book, the authors cover the basic methods and advances within distance sampling that are most valuable to practitioners and in ecology more broadly. This is the fourth book dedicated to distance sampling. In the decade since the last book published, there have been a number of new developments. The intervening years have also shown which advances are of most use. This self-contained book covers topics from the previous publications, while also including recent developments in method, software and application. Distance sampling refers to a suite of methods, including line and point transect sampling, in which animal density or abundance is estimated from a sample of distances to detected individuals. The book illustrates these methods through case studies; data sets and computer code are supplied to readers through the book’s accompanying website.  Some of the case studies use the software Distance, while others use R code. The book is in three parts.  The first part addresses basic methods, the ...

  10. Short assessment of the Big Five: robust across survey methods except telephone interviewing.

    Science.gov (United States)

    Lang, Frieder R; John, Dennis; Lüdtke, Oliver; Schupp, Jürgen; Wagner, Gert G

    2011-06-01

    We examined measurement invariance and age-related robustness of a short 15-item Big Five Inventory (BFI-S) of personality dimensions, which is well suited for applications in large-scale multidisciplinary surveys. The BFI-S was assessed in three different interviewing conditions: computer-assisted or paper-assisted face-to-face interviewing, computer-assisted telephone interviewing, and a self-administered questionnaire. Randomized probability samples from a large-scale German panel survey and a related probability telephone study were used in order to test method effects on self-report measures of personality characteristics across early, middle, and late adulthood. Exploratory structural equation modeling was used in order to test for measurement invariance of the five-factor model of personality trait domains across different assessment methods. For the short inventory, findings suggest strong robustness of self-report measures of personality dimensions among young and middle-aged adults. In old age, telephone interviewing was associated with greater distortions in reliable personality assessment. It is concluded that the greater mental workload of telephone interviewing limits the reliability of self-report personality assessment. Face-to-face surveys and self-administrated questionnaire completion are clearly better suited than phone surveys when personality traits in age-heterogeneous samples are assessed.

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

    African Journals Online (AJOL)

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

  12. Metagenomic survey of bacterial diversity in the atmosphere of Mexico City using different sampling methods.

    Science.gov (United States)

    Serrano-Silva, N; Calderón-Ezquerro, M C

    2018-04-01

    The identification of airborne bacteria has traditionally been performed by retrieval in culture media, but the bacterial diversity in the air is underestimated using this method because many bacteria are not readily cultured. Advances in DNA sequencing technology have produced a broad knowledge of genomics and metagenomics, which can greatly improve our ability to identify and study the diversity of airborne bacteria. However, researchers are facing several challenges, particularly the efficient retrieval of low-density microorganisms from the air and the lack of standardized protocols for sample collection and processing. In this study, we tested three methods for sampling bioaerosols - a Durham-type spore trap (Durham), a seven-day recording volumetric spore trap (HST), and a high-throughput 'Jet' spore and particle sampler (Jet) - and recovered metagenomic DNA for 16S rDNA sequencing. Samples were simultaneously collected with the three devices during one week, and the sequencing libraries were analyzed. A simple and efficient method for collecting bioaerosols and extracting good quality DNA for high-throughput sequencing was standardized. The Durham sampler collected preferentially Cyanobacteria, the HST Actinobacteria, Proteobacteria and Firmicutes, and the Jet mainly Proteobacteria and Firmicutes. The HST sampler collected the largest amount of airborne bacterial diversity. More experiments are necessary to select the right sampler, depending on study objectives, which may require monitoring and collecting specific airborne bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Nested PCR detection of malaria directly using blood filter paper samples from epidemiological surveys.

    Science.gov (United States)

    Li, Peipei; Zhao, Zhenjun; Wang, Ying; Xing, Hua; Parker, Daniel M; Yang, Zhaoqing; Baum, Elizabeth; Li, Wenli; Sattabongkot, Jetsumon; Sirichaisinthop, Jeeraphat; Li, Shuying; Yan, Guiyun; Cui, Liwang; Fan, Qi

    2014-05-08

    Nested PCR is considered a sensitive and specific method for detecting malaria parasites and is especially useful in epidemiological surveys. However, the preparation of DNA templates for PCR is often time-consuming and costly. A simplified PCR method was developed to directly use a small blood filter paper square (2 × 2 mm) as the DNA template after treatment with saponin. This filter paper-based nested PCR method (FP-PCR) was compared to microscopy and standard nested PCR with DNA extracted by using a Qiagen DNA mini kit from filter paper blood spots of 204 febrile cases. The FP-PCR technique was further applied to evaluate malaria infections in 1,708 participants from cross-sectional epidemiological surveys conducted in Myanmar and Thailand. The FP-PCR method had a detection limit of ~0.2 parasites/μL blood, estimated using cultured Plasmodium falciparum parasites. With 204 field samples, the sensitivity of the FP-PCR method was comparable to that of the standard nested PCR method, which was significantly higher than that of microscopy. Application of the FP-PCR method in large cross-sectional studies conducted in Myanmar and Thailand detected 1.9% (12/638) and 6.2% (66/1,070) asymptomatic Plasmodium infections, respectively, as compared to the detection rates of 1.3% (8/638) and 0.04% (4/1,070) by microscopy. This FP-PCR method was much more sensitive than microscopy in detecting Plasmodium infections. It drastically increased the detection sensitivity of asymptomatic infections in cross-sectional surveys conducted in Thailand and Myanmar, suggesting that this FP-PCR method has a potential for future applications in malaria epidemiology studies.

  14. Random sampling of quantum states: a survey of methods and some issues regarding the Overparametrized Method

    International Nuclear Information System (INIS)

    Maziero, Jonas

    2015-01-01

    The numerical generation of random quantum states (RQS) is an important procedure for investigations in quantum information science. Here, we review some methods that may be used for performing that task. We start by presenting a simple procedure for generating random state vectors, for which the main tool is the random sampling of unbiased discrete probability distributions (DPD). Afterwards, the creation of random density matrices is addressed. In this context, we first present the standard method, which consists in using the spectral decomposition of a quantum state for getting RQS from random DPDs and random unitary matrices. In the sequence, the Bloch vector parametrization method is described. This approach, despite being useful in several instances, is not in general convenient for RQS generation. In the last part of the article, we regard the overparametrized method (OPM) and the related Ginibre and Bures techniques. The OPM can be used to create random positive semidefinite matrices with unit trace from randomly produced general complex matrices in a simple way that is friendly for numerical implementations. We consider a physically relevant issue related to the possible domains that may be used for the real and imaginary parts of the elements of such general complex matrices. Subsequently, a too fast concentration of measure in the quantum state space that appears in this parametrization is noticed. (author)

  15. Concentration comparison of selected constituents between groundwater samples collected within the Missouri River alluvial aquifer using purge and pump and grab-sampling methods, near the city of Independence, Missouri, 2013

    Science.gov (United States)

    Krempa, Heather M.

    2015-10-29

    The U.S. Geological Survey, in cooperation with the City of Independence, Missouri, Water Department, has historically collected water-quality samples using the purge and pump method (hereafter referred to as pump method) to identify potential contamination in groundwater supply wells within the Independence well field. If grab sample results are comparable to the pump method, grab samplers may reduce time, labor, and overall cost. This study was designed to compare constituent concentrations between samples collected within the Independence well field using the pump method and the grab method.

  16. Independent random sampling methods

    CERN Document Server

    Martino, Luca; Míguez, Joaquín

    2018-01-01

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

  17. A rapid method for the determination on fluoride in geological samples

    International Nuclear Information System (INIS)

    Josephson, M.; Cook, E.B.T.; Dixon, K.

    1977-01-01

    An account is given of a rapid procedure for the determination by use of the specific-ion electrode of fluoride in geological samples. The sample is fused with sodium hydroxide in a nickel crucible in a muffle furnace. The melt is leached with water, a buffer solution of ammonium citrate is added, and the fluoride activity is measured with a specific-ion electrode. All operations are carried out in the crucible, making possible approximately 100 determinations a day. The precision of the method is approximately 10 per cent at a fluoride concentration of 500 p.p.m., which is acceptable for geological-survey work [af

  18. A method of language sampling

    DEFF Research Database (Denmark)

    Rijkhoff, Jan; Bakker, Dik; Hengeveld, Kees

    1993-01-01

    In recent years more attention is paid to the quality of language samples in typological work. Without an adequate sampling strategy, samples may suffer from various kinds of bias. In this article we propose a sampling method in which the genetic criterion is taken as the most important: samples...... created with this method will reflect optimally the diversity of the languages of the world. On the basis of the internal structure of each genetic language tree a measure is computed that reflects the linguistic diversity in the language families represented by these trees. This measure is used...... to determine how many languages from each phylum should be selected, given any required sample size....

  19. Global review of health care surveys using lot quality assurance sampling (LQAS), 1984-2004.

    Science.gov (United States)

    Robertson, Susan E; Valadez, Joseph J

    2006-09-01

    We conducted a global review on the use of lot quality assurance sampling (LQAS) to assess health care services, health behaviors, and disease burden. Publications and reports on LQAS surveys were sought from Medline and five other electronic databases; the World Health Organization; the World Bank; governments, nongovernmental organizations, and individual scientists. We identified a total of 805 LQAS surveys conducted by different management groups during January 1984 through December 2004. There was a striking increase in the annual number of LQAS surveys conducted in 2000-2004 (128/year) compared with 1984-1999 (10/year). Surveys were conducted in 55 countries, and in 12 of these countries there were 10 or more LQAS surveys. Geographically, 317 surveys (39.4%) were conducted in Africa, 197 (28.5%) in the Americas, 115 (14.3%) in the Eastern Mediterranean, 114 (14.2%) in South-East Asia, 48 (6.0%) in Europe, and 14 (1.8%) in the Western Pacific. Health care parameters varied, and some surveys assessed more than one parameter. There were 320 surveys about risk factors for HIV/AIDS/sexually transmitted infections; 266 surveys on immunization coverage, 240 surveys post-disasters, 224 surveys on women's health, 142 surveys on growth and nutrition, 136 surveys on diarrheal disease control, and 88 surveys on quality management. LQAS surveys to assess disease burden included 23 neonatal tetanus mortality surveys and 12 surveys on other diseases. LQAS is a practical field method which increasingly is being applied in assessment of preventive and curative health services, and may offer new research opportunities to social scientists. When LQAS data are collected recurrently at multiple time points, they can be used to measure the spatial variation in behavior change. Such data provide insight into understanding relationships between various investments in social, human, and physical capital, and into the effectiveness of different public health strategies in achieving

  20. Methods used to conduct the pan-European Union survey on consumer attitudes to physical activity, body weight and health.

    Science.gov (United States)

    Kearney, J M; Kearney, M J; McElhone, S; Gibney, M J

    1999-03-01

    The purpose of conducting this survey was to identify data on consumer attitudes towards and beliefs about physical activity, body weight and health among the 15 countries of the EU. A cross-sectional study to get a picture of the attitudes to physical activity, body weight and health in the EU. For this, it was considered important that samples be nationally representative so that inferences drawn from the data could be applied to the population in each country as well as to the EU population as a whole. Using a non-probability sampling method employing quota controls (and the national weight) we obtained large sample sizes from each country which were nationally representative in terms of the variables age, sex and regional distribution. To ensure samples were truly nationally representative a national weight was used when analysing the data using the same characteristics as those used to define quotas. When examining pooled estimates for the total EU sample a population weight was applied. In total, 15,239 subjects aged 15 years and upwards in the EU completed the survey. This article gives details on the methods used in carrying out the survey from design of the questionnaire to sample selection, questionnaire administration and analysis of the data. The methods and their limitations are discussed.

  1. Sampling guidelines for oral fluid-based surveys of group-housed animals.

    Science.gov (United States)

    Rotolo, Marisa L; Sun, Yaxuan; Wang, Chong; Giménez-Lirola, Luis; Baum, David H; Gauger, Phillip C; Harmon, Karen M; Hoogland, Marlin; Main, Rodger; Zimmerman, Jeffrey J

    2017-09-01

    Formulas and software for calculating sample size for surveys based on individual animal samples are readily available. However, sample size formulas are not available for oral fluids and other aggregate samples that are increasingly used in production settings. Therefore, the objective of this study was to develop sampling guidelines for oral fluid-based porcine reproductive and respiratory syndrome virus (PRRSV) surveys in commercial swine farms. Oral fluid samples were collected in 9 weekly samplings from all pens in 3 barns on one production site beginning shortly after placement of weaned pigs. Samples (n=972) were tested by real-time reverse-transcription PCR (RT-rtPCR) and the binary results analyzed using a piecewise exponential survival model for interval-censored, time-to-event data with misclassification. Thereafter, simulation studies were used to study the barn-level probability of PRRSV detection as a function of sample size, sample allocation (simple random sampling vs fixed spatial sampling), assay diagnostic sensitivity and specificity, and pen-level prevalence. These studies provided estimates of the probability of detection by sample size and within-barn prevalence. Detection using fixed spatial sampling was as good as, or better than, simple random sampling. Sampling multiple barns on a site increased the probability of detection with the number of barns sampled. These results are relevant to PRRSV control or elimination projects at the herd, regional, or national levels, but the results are also broadly applicable to contagious pathogens of swine for which oral fluid tests of equivalent performance are available. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  2. Molecular Weights of Bovine and Porcine Heparin Samples: Comparison of Chromatographic Methods and Results of a Collaborative Survey

    Directory of Open Access Journals (Sweden)

    Sabrina Bertini

    2017-07-01

    Full Text Available In a collaborative study involving six laboratories in the USA, Europe, and India the molecular weight distributions of a panel of heparin sodium samples were determined, in order to compare heparin sodium of bovine intestinal origin with that of bovine lung and porcine intestinal origin. Porcine samples met the current criteria as laid out in the USP Heparin Sodium monograph. Bovine lung heparin samples had consistently lower average molecular weights. Bovine intestinal heparin was variable in molecular weight; some samples fell below the USP limits, some fell within these limits and others fell above the upper limits. These data will inform the establishment of pharmacopeial acceptance criteria for heparin sodium derived from bovine intestinal mucosa. The method for MW determination as described in the USP monograph uses a single, broad standard calibrant to characterize the chromatographic profile of heparin sodium on high-resolution silica-based GPC columns. These columns may be short-lived in some laboratories. Using the panel of samples described above, methods based on the use of robust polymer-based columns have been developed. In addition to the use of the USP’s broad standard calibrant for heparin sodium with these columns, a set of conditions have been devised that allow light-scattering detected molecular weight characterization of heparin sodium, giving results that agree well with the monograph method. These findings may facilitate the validation of variant chromatographic methods with some practical advantages over the USP monograph method.

  3. Molecular Weights of Bovine and Porcine Heparin Samples: Comparison of Chromatographic Methods and Results of a Collaborative Survey.

    Science.gov (United States)

    Bertini, Sabrina; Risi, Giulia; Guerrini, Marco; Carrick, Kevin; Szajek, Anita Y; Mulloy, Barbara

    2017-07-19

    In a collaborative study involving six laboratories in the USA, Europe, and India the molecular weight distributions of a panel of heparin sodium samples were determined, in order to compare heparin sodium of bovine intestinal origin with that of bovine lung and porcine intestinal origin. Porcine samples met the current criteria as laid out in the USP Heparin Sodium monograph. Bovine lung heparin samples had consistently lower average molecular weights. Bovine intestinal heparin was variable in molecular weight; some samples fell below the USP limits, some fell within these limits and others fell above the upper limits. These data will inform the establishment of pharmacopeial acceptance criteria for heparin sodium derived from bovine intestinal mucosa. The method for MW determination as described in the USP monograph uses a single, broad standard calibrant to characterize the chromatographic profile of heparin sodium on high-resolution silica-based GPC columns. These columns may be short-lived in some laboratories. Using the panel of samples described above, methods based on the use of robust polymer-based columns have been developed. In addition to the use of the USP's broad standard calibrant for heparin sodium with these columns, a set of conditions have been devised that allow light-scattering detected molecular weight characterization of heparin sodium, giving results that agree well with the monograph method. These findings may facilitate the validation of variant chromatographic methods with some practical advantages over the USP monograph method.

  4. Point process models for spatio-temporal distance sampling data from a large-scale survey of blue whales

    KAUST Repository

    Yuan, Yuan; Bachl, Fabian E.; Lindgren, Finn; Borchers, David L.; Illian, Janine B.; Buckland, Stephen T.; Rue, Haavard; Gerrodette, Tim

    2017-01-01

    Distance sampling is a widely used method for estimating wildlife population abundance. The fact that conventional distance sampling methods are partly design-based constrains the spatial resolution at which animal density can be estimated using these methods. Estimates are usually obtained at survey stratum level. For an endangered species such as the blue whale, it is desirable to estimate density and abundance at a finer spatial scale than stratum. Temporal variation in the spatial structure is also important. We formulate the process generating distance sampling data as a thinned spatial point process and propose model-based inference using a spatial log-Gaussian Cox process. The method adopts a flexible stochastic partial differential equation (SPDE) approach to model spatial structure in density that is not accounted for by explanatory variables, and integrated nested Laplace approximation (INLA) for Bayesian inference. It allows simultaneous fitting of detection and density models and permits prediction of density at an arbitrarily fine scale. We estimate blue whale density in the Eastern Tropical Pacific Ocean from thirteen shipboard surveys conducted over 22 years. We find that higher blue whale density is associated with colder sea surface temperatures in space, and although there is some positive association between density and mean annual temperature, our estimates are consistent with no trend in density across years. Our analysis also indicates that there is substantial spatially structured variation in density that is not explained by available covariates.

  5. Point process models for spatio-temporal distance sampling data from a large-scale survey of blue whales

    KAUST Repository

    Yuan, Yuan

    2017-12-28

    Distance sampling is a widely used method for estimating wildlife population abundance. The fact that conventional distance sampling methods are partly design-based constrains the spatial resolution at which animal density can be estimated using these methods. Estimates are usually obtained at survey stratum level. For an endangered species such as the blue whale, it is desirable to estimate density and abundance at a finer spatial scale than stratum. Temporal variation in the spatial structure is also important. We formulate the process generating distance sampling data as a thinned spatial point process and propose model-based inference using a spatial log-Gaussian Cox process. The method adopts a flexible stochastic partial differential equation (SPDE) approach to model spatial structure in density that is not accounted for by explanatory variables, and integrated nested Laplace approximation (INLA) for Bayesian inference. It allows simultaneous fitting of detection and density models and permits prediction of density at an arbitrarily fine scale. We estimate blue whale density in the Eastern Tropical Pacific Ocean from thirteen shipboard surveys conducted over 22 years. We find that higher blue whale density is associated with colder sea surface temperatures in space, and although there is some positive association between density and mean annual temperature, our estimates are consistent with no trend in density across years. Our analysis also indicates that there is substantial spatially structured variation in density that is not explained by available covariates.

  6. U.S. residential consumer product information: Validation of methods for post-stratification weighting of Amazon Mechanical Turk surveys

    Energy Technology Data Exchange (ETDEWEB)

    Greenblatt, Jeffery B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Yang, Hung-Chia [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Desroches, Louis-Benoit [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Young, Scott J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Beraki, Bereket [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Price, Sarah K. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pratt, Stacy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Willem, Henry [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Donovan, Sally M. [Consultant, Melbourne (Australia)

    2013-04-01

    We present two post-stratification weighting methods to validate survey data collected using Amazon Mechanical Turk (AMT). Two surveys focused on appliance and consumer electronics devices were administered in the spring and summer of 2012 to each of approximately 3,000 U.S. households. Specifically, the surveys asked questions about residential refrigeration products, televisions (TVs) and set-top boxes (STBs). Filtered data were assigned weights using each of two weighting methods, termed “sequential” and “simultaneous,” by examining up to eight demographic variables (income, education, gender, race, Hispanic origin, number of occupants, ages of occupants, and geographic region) in comparison to reference U.S. demographic data from the 2009 Residential Energy Consumption Survey (RECS). Five key questions from the surveys (number of refrigerators, number of freezers, number of TVs, number of STBs and primary service provider) were evaluated with a set of statistical tests to determine whether either method improved the agreement of AMT with reference data, and if so, which method was better. The statistical tests used were: differences in proportions, distributions of proportions (using Pearson’s chi-squared test), and differences in average numbers of devices as functions of all demographic variables. The results indicated that both methods generally improved the agreement between AMT and reference data, sometimes greatly, but that the simultaneous method was usually superior to the sequential method. Some differences in sample populations were found between the AMT and reference data. Differences in the proportion of STBs reflected large changes in the STB market since the time our reference data was acquired in 2009. Differences in the proportions of some primary service providers suggested real sample bias, with the possible explanation that AMT user are more likely to subscribe to providers who also provide home internet service. Differences in

  7. Optimum sample size to estimate mean parasite abundance in fish parasite surveys

    Directory of Open Access Journals (Sweden)

    Shvydka S.

    2018-03-01

    Full Text Available To reach ethically and scientifically valid mean abundance values in parasitological and epidemiological studies this paper considers analytic and simulation approaches for sample size determination. The sample size estimation was carried out by applying mathematical formula with predetermined precision level and parameter of the negative binomial distribution estimated from the empirical data. A simulation approach to optimum sample size determination aimed at the estimation of true value of the mean abundance and its confidence interval (CI was based on the Bag of Little Bootstraps (BLB. The abundance of two species of monogenean parasites Ligophorus cephali and L. mediterraneus from Mugil cephalus across the Azov-Black Seas localities were subjected to the analysis. The dispersion pattern of both helminth species could be characterized as a highly aggregated distribution with the variance being substantially larger than the mean abundance. The holistic approach applied here offers a wide range of appropriate methods in searching for the optimum sample size and the understanding about the expected precision level of the mean. Given the superior performance of the BLB relative to formulae with its few assumptions, the bootstrap procedure is the preferred method. Two important assessments were performed in the present study: i based on CIs width a reasonable precision level for the mean abundance in parasitological surveys of Ligophorus spp. could be chosen between 0.8 and 0.5 with 1.6 and 1x mean of the CIs width, and ii the sample size equal 80 or more host individuals allows accurate and precise estimation of mean abundance. Meanwhile for the host sample size in range between 25 and 40 individuals, the median estimates showed minimal bias but the sampling distribution skewed to the low values; a sample size of 10 host individuals yielded to unreliable estimates.

  8. Samples and data accessibility in research biobanks: an explorative survey

    Directory of Open Access Journals (Sweden)

    Marco Capocasa

    2016-02-01

    Full Text Available Biobanks, which contain human biological samples and/or data, provide a crucial contribution to the progress of biomedical research. However, the effective and efficient use of biobank resources depends on their accessibility. In fact, making bio-resources promptly accessible to everybody may increase the benefits for society. Furthermore, optimizing their use and ensuring their quality will promote scientific creativity and, in general, contribute to the progress of bio-medical research. Although this has become a rather common belief, several laboratories are still secretive and continue to withhold samples and data. In this study, we conducted a questionnaire-based survey in order to investigate sample and data accessibility in research biobanks operating all over the world. The survey involved a total of 46 biobanks. Most of them gave permission to access their samples (95.7% and data (85.4%, but free and unconditioned accessibility seemed not to be common practice. The analysis of the guidelines regarding the accessibility to resources of the biobanks that responded to the survey highlights three issues: (i the request for applicants to explain what they would like to do with the resources requested; (ii the role of funding, public or private, in the establishment of fruitful collaborations between biobanks and research labs; (iii the request of co-authorship in order to give access to their data. These results suggest that economic and academic aspects are involved in determining the extent of sample and data sharing stored in biobanks. As a second step of this study, we investigated the reasons behind the high diversity of requirements to access biobank resources. The analysis of informative answers suggested that the different modalities of resource accessibility seem to be largely influenced by both social context and legislation of the countries where the biobanks operate.

  9. SWOT ANALYSIS ON SAMPLING METHOD

    Directory of Open Access Journals (Sweden)

    CHIS ANCA OANA

    2014-07-01

    Full Text Available Audit sampling involves the application of audit procedures to less than 100% of items within an account balance or class of transactions. Our article aims to study audit sampling in audit of financial statements. As an audit technique largely used, in both its statistical and nonstatistical form, the method is very important for auditors. It should be applied correctly for a fair view of financial statements, to satisfy the needs of all financial users. In order to be applied correctly the method must be understood by all its users and mainly by auditors. Otherwise the risk of not applying it correctly would cause loose of reputation and discredit, litigations and even prison. Since there is not a unitary practice and methodology for applying the technique, the risk of incorrectly applying it is pretty high. The SWOT analysis is a technique used that shows the advantages, disadvantages, threats and opportunities. We applied SWOT analysis in studying the sampling method, from the perspective of three players: the audit company, the audited entity and users of financial statements. The study shows that by applying the sampling method the audit company and the audited entity both save time, effort and money. The disadvantages of the method are difficulty in applying and understanding its insight. Being largely used as an audit method and being a factor of a correct audit opinion, the sampling method’s advantages, disadvantages, threats and opportunities must be understood by auditors.

  10. Nationwide survey of policies and practices related to capillary blood sampling in medical laboratories in Croatia

    Science.gov (United States)

    Krleza, Jasna Lenicek

    2014-01-01

    Introduction: Capillary sampling is increasingly used to obtain blood for laboratory tests in volumes as small as necessary and as non-invasively as possible. Whether capillary blood sampling is also frequent in Croatia, and whether it is performed according to international laboratory standards is unclear. Materials and methods: All medical laboratories that participate in the Croatian National External Quality Assessment Program (N = 204) were surveyed on-line to collect information about the laboratory’s parent institution, patient population, types and frequencies of laboratory tests based on capillary blood samples, choice of reference intervals, and policies and procedures specifically related to capillary sampling. Sampling practices were compared with guidelines from the Clinical and Laboratory Standards Institute (CLSI) and the World Health Organization (WHO). Results: Of the 204 laboratories surveyed, 174 (85%) responded with complete questionnaires. Among the 174 respondents, 155 (89%) reported that they routinely perform capillary sampling, which is carried out by laboratory staff in 118 laboratories (76%). Nearly half of respondent laboratories (48%) do not have a written protocol including order of draw for multiple sampling. A single puncture site is used to provide capillary blood for up to two samples at 43% of laboratories that occasionally or regularly perform such sampling. Most respondents (88%) never perform arterialisation prior to capillary blood sampling. Conclusions: Capillary blood sampling is highly prevalent in Croatia across different types of clinical facilities and patient populations. Capillary sampling procedures are not standardised in the country, and the rate of laboratory compliance with CLSI and WHO guidelines is low. PMID:25351353

  11. Evaluating the quality of sampling frames used in European cross-national surveys

    NARCIS (Netherlands)

    Maineri, A.M.; Scherpenzeel, A.; Bristle, Johanna; Pflüger, Senta-Melissa; Butt, Sarah; Zins, Stefan; Emery, Tom; Luijkx, R.

    This report addresses the quality of the population registers which are currently being used as sampling frames in countries participating in the four cross-European surveys cooperating in SERISS: the European Social Survey (ESS), the European Values Study (EVS), the Gender and Generations Program

  12. Evaluation of Respondent-Driven Sampling

    Science.gov (United States)

    McCreesh, Nicky; Frost, Simon; Seeley, Janet; Katongole, Joseph; Tarsh, Matilda Ndagire; Ndunguse, Richard; Jichi, Fatima; Lunel, Natasha L; Maher, Dermot; Johnston, Lisa G; Sonnenberg, Pam; Copas, Andrew J; Hayes, Richard J; White, Richard G

    2012-01-01

    Background Respondent-driven sampling is a novel variant of link-tracing sampling for estimating the characteristics of hard-to-reach groups, such as HIV prevalence in sex-workers. Despite its use by leading health organizations, the performance of this method in realistic situations is still largely unknown. We evaluated respondent-driven sampling by comparing estimates from a respondent-driven sampling survey with total-population data. Methods Total-population data on age, tribe, religion, socioeconomic status, sexual activity and HIV status were available on a population of 2402 male household-heads from an open cohort in rural Uganda. A respondent-driven sampling (RDS) survey was carried out in this population, employing current methods of sampling (RDS sample) and statistical inference (RDS estimates). Analyses were carried out for the full RDS sample and then repeated for the first 250 recruits (small sample). Results We recruited 927 household-heads. Full and small RDS samples were largely representative of the total population, but both samples under-represented men who were younger, of higher socioeconomic status, and with unknown sexual activity and HIV status. Respondent-driven-sampling statistical-inference methods failed to reduce these biases. Only 31%-37% (depending on method and sample size) of RDS estimates were closer to the true population proportions than the RDS sample proportions. Only 50%-74% of respondent-driven-sampling bootstrap 95% confidence intervals included the population proportion. Conclusions Respondent-driven sampling produced a generally representative sample of this well-connected non-hidden population. However, current respondent-driven-sampling inference methods failed to reduce bias when it occurred. Whether the data required to remove bias and measure precision can be collected in a respondent-driven sampling survey is unresolved. Respondent-driven sampling should be regarded as a (potentially superior) form of convenience-sampling

  13. Sampling system and method

    Science.gov (United States)

    Decker, David L.; Lyles, Brad F.; Purcell, Richard G.; Hershey, Ronald Lee

    2013-04-16

    The present disclosure provides an apparatus and method for coupling conduit segments together. A first pump obtains a sample and transmits it through a first conduit to a reservoir accessible by a second pump. The second pump further conducts the sample from the reservoir through a second conduit.

  14. A method of language sampling

    DEFF Research Database (Denmark)

    Rijkhoff, Jan; Bakker, Dik; Hengeveld, Kees

    1993-01-01

    In recent years more attention is paid to the quality of language samples in typological work. Without an adequate sampling strategy, samples may suffer from various kinds of bias. In this article we propose a sampling method in which the genetic criterion is taken as the most important: samples...... to determine how many languages from each phylum should be selected, given any required sample size....

  15. Sampling in Qualitative Research: Rationale, Issues, and Methods

    OpenAIRE

    LUBORSKY, MARK R.; RUBINSTEIN, ROBERT L.

    1995-01-01

    In gerontology the most recognized and elaborate discourse about sampling is generally thought to be in quantitative research associated with survey research and medical research. But sampling has long been a central concern in the social and humanistic inquiry, albeit in a different guise suited to the different goals. There is a need for more explicit discussion of qualitative sampling issues. This article will outline the guiding principles and rationales, features, and practices of sampli...

  16. Does self-selection affect samples' representativeness in online surveys? An investigation in online video game research.

    Science.gov (United States)

    Khazaal, Yasser; van Singer, Mathias; Chatton, Anne; Achab, Sophia; Zullino, Daniele; Rothen, Stephane; Khan, Riaz; Billieux, Joel; Thorens, Gabriel

    2014-07-07

    The number of medical studies performed through online surveys has increased dramatically in recent years. Despite their numerous advantages (eg, sample size, facilitated access to individuals presenting stigmatizing issues), selection bias may exist in online surveys. However, evidence on the representativeness of self-selected samples in online studies is patchy. Our objective was to explore the representativeness of a self-selected sample of online gamers using online players' virtual characters (avatars). All avatars belonged to individuals playing World of Warcraft (WoW), currently the most widely used online game. Avatars' characteristics were defined using various games' scores, reported on the WoW's official website, and two self-selected samples from previous studies were compared with a randomly selected sample of avatars. We used scores linked to 1240 avatars (762 from the self-selected samples and 478 from the random sample). The two self-selected samples of avatars had higher scores on most of the assessed variables (except for guild membership and exploration). Furthermore, some guilds were overrepresented in the self-selected samples. Our results suggest that more proficient players or players more involved in the game may be more likely to participate in online surveys. Caution is needed in the interpretation of studies based on online surveys that used a self-selection recruitment procedure. Epidemiological evidence on the reduced representativeness of sample of online surveys is warranted.

  17. Sampling strategy for a large scale indoor radiation survey - a pilot project

    International Nuclear Information System (INIS)

    Strand, T.; Stranden, E.

    1986-01-01

    Optimisation of a stratified random sampling strategy for large scale indoor radiation surveys is discussed. It is based on the results from a small scale pilot project where variances in dose rates within different categories of houses were assessed. By selecting a predetermined precision level for the mean dose rate in a given region, the number of measurements needed can be optimised. The results of a pilot project in Norway are presented together with the development of the final sampling strategy for a planned large scale survey. (author)

  18. Evaluation of respondent-driven sampling.

    Science.gov (United States)

    McCreesh, Nicky; Frost, Simon D W; Seeley, Janet; Katongole, Joseph; Tarsh, Matilda N; Ndunguse, Richard; Jichi, Fatima; Lunel, Natasha L; Maher, Dermot; Johnston, Lisa G; Sonnenberg, Pam; Copas, Andrew J; Hayes, Richard J; White, Richard G

    2012-01-01

    Respondent-driven sampling is a novel variant of link-tracing sampling for estimating the characteristics of hard-to-reach groups, such as HIV prevalence in sex workers. Despite its use by leading health organizations, the performance of this method in realistic situations is still largely unknown. We evaluated respondent-driven sampling by comparing estimates from a respondent-driven sampling survey with total population data. Total population data on age, tribe, religion, socioeconomic status, sexual activity, and HIV status were available on a population of 2402 male household heads from an open cohort in rural Uganda. A respondent-driven sampling (RDS) survey was carried out in this population, using current methods of sampling (RDS sample) and statistical inference (RDS estimates). Analyses were carried out for the full RDS sample and then repeated for the first 250 recruits (small sample). We recruited 927 household heads. Full and small RDS samples were largely representative of the total population, but both samples underrepresented men who were younger, of higher socioeconomic status, and with unknown sexual activity and HIV status. Respondent-driven sampling statistical inference methods failed to reduce these biases. Only 31%-37% (depending on method and sample size) of RDS estimates were closer to the true population proportions than the RDS sample proportions. Only 50%-74% of respondent-driven sampling bootstrap 95% confidence intervals included the population proportion. Respondent-driven sampling produced a generally representative sample of this well-connected nonhidden population. However, current respondent-driven sampling inference methods failed to reduce bias when it occurred. Whether the data required to remove bias and measure precision can be collected in a respondent-driven sampling survey is unresolved. Respondent-driven sampling should be regarded as a (potentially superior) form of convenience sampling method, and caution is required

  19. Subrandom methods for multidimensional nonuniform sampling.

    Science.gov (United States)

    Worley, Bradley

    2016-08-01

    Methods of nonuniform sampling that utilize pseudorandom number sequences to select points from a weighted Nyquist grid are commonplace in biomolecular NMR studies, due to the beneficial incoherence introduced by pseudorandom sampling. However, these methods require the specification of a non-arbitrary seed number in order to initialize a pseudorandom number generator. Because the performance of pseudorandom sampling schedules can substantially vary based on seed number, this can complicate the task of routine data collection. Approaches such as jittered sampling and stochastic gap sampling are effective at reducing random seed dependence of nonuniform sampling schedules, but still require the specification of a seed number. This work formalizes the use of subrandom number sequences in nonuniform sampling as a means of seed-independent sampling, and compares the performance of three subrandom methods to their pseudorandom counterparts using commonly applied schedule performance metrics. Reconstruction results using experimental datasets are also provided to validate claims made using these performance metrics. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Design and methods in a survey of living conditions in the Arctic - the SLiCA study.

    Science.gov (United States)

    Eliassen, Bent-Martin; Melhus, Marita; Kruse, Jack; Poppel, Birger; Broderstad, Ann Ragnhild

    2012-03-19

    The main objective of this study is to describe the methods and design of the survey of living conditions in the Arctic (SLiCA), relevant participation rates and the distribution of participants, as applicable to the survey data in Alaska, Greenland and Norway. This article briefly addresses possible selection bias in the data and also the ways to tackle it in future studies. Population-based cross-sectional survey. Indigenous individuals aged 16 years and older, living in Greenland, Alaska and in traditional settlement areas in Norway, were invited to participate. Random sampling methods were applied in Alaska and Greenland, while non-probability sampling methods were applied in Norway. Data were collected in 3 periods: in Alaska, from January 2002 to February 2003; in Greenland, from December 2003 to August 2006; and in Norway, in 2003 and from June 2006 to June 2008. The principal method in SLiCA was standardised face-to-face interviews using a questionnaire. A total of 663, 1,197 and 445 individuals were interviewed in Alaska, Greenland and Norway, respectively. Very high overall participation rates of 83% were obtained in Greenland and Alaska, while a more conventional rate of 57% was achieved in Norway. A predominance of female respondents was obtained in Alaska. Overall, the Sami cohort is older than the cohorts from Greenland and Alaska. Preliminary assessments suggest that selection bias in the Sami sample is plausible but not a major threat. Few or no threats to validity are detected in the data from Alaska and Greenland. Despite different sampling and recruitment methods, and sociocultural differences, a unique database has been generated, which shall be used to explore relationships between health and other living conditions variables.

  1. Some connections between importance sampling and enhanced sampling methods in molecular dynamics.

    Science.gov (United States)

    Lie, H C; Quer, J

    2017-11-21

    In molecular dynamics, enhanced sampling methods enable the collection of better statistics of rare events from a reference or target distribution. We show that a large class of these methods is based on the idea of importance sampling from mathematical statistics. We illustrate this connection by comparing the Hartmann-Schütte method for rare event simulation (J. Stat. Mech. Theor. Exp. 2012, P11004) and the Valsson-Parrinello method of variationally enhanced sampling [Phys. Rev. Lett. 113, 090601 (2014)]. We use this connection in order to discuss how recent results from the Monte Carlo methods literature can guide the development of enhanced sampling methods.

  2. Perpendicular distance sampling: an alternative method for sampling downed coarse woody debris

    Science.gov (United States)

    Michael S. Williams; Jeffrey H. Gove

    2003-01-01

    Coarse woody debris (CWD) plays an important role in many forest ecosystem processes. In recent years, a number of new methods have been proposed to sample CWD. These methods select individual logs into the sample using some form of unequal probability sampling. One concern with most of these methods is the difficulty in estimating the volume of each log. A new method...

  3. Sampling method of environmental radioactivity monitoring

    International Nuclear Information System (INIS)

    1984-01-01

    This manual provides sampling methods of environmental samples of airborne dust, precipitated dust, precipitated water (rain or snow), fresh water, soil, river sediment or lake sediment, discharged water from a nuclear facility, grains, tea, milk, pasture grass, limnetic organisms, daily diet, index organisms, sea water, marine sediment, marine organisms, and that for tritium and radioiodine determination for radiation monitoring from radioactive fallout or radioactivity release by nuclear facilities. This manual aims at the presentation of standard sampling procedures for environmental radioactivity monitoring regardless of monitoring objectives, and shows preservation method of environmental samples acquired at the samplingpoint for radiation counting for those except human body. Sampling techniques adopted in this manual is decided by the criteria that they are suitable for routine monitoring and any special skillfulness is not necessary. Based on the above-mentioned principle, this manual presents outline and aims of sampling, sampling position or object, sampling quantity, apparatus, equipment or vessel for sampling, sampling location, sampling procedures, pretreatment and preparation procedures of a sample for radiation counting, necessary recording items for sampling and sample transportation procedures. Special attention is described in the chapter of tritium and radioiodine because these radionuclides might be lost by the above-mentioned sample preservation method for radiation counting of less volatile radionuclides than tritium or radioiodine. (Takagi, S.)

  4. A sample of galaxy pairs identified from the LAMOST spectral survey and the Sloan Digital Sky Survey

    International Nuclear Information System (INIS)

    Shen, Shi-Yin; Argudo-Fernández, Maria; Chen, Li; Feng, Shuai; Hou, Jin-Liang; Shao, Zheng-Yi; Chen, Xiao-Yan; Luo, A-Li; Wu, Hong; Yang, Hai-Feng; Yang, Ming; Hou, Yong-Hui; Wang, Yue-Fei; Jiang, Peng; Wang, Ting-Gui; Jing, Yi-Peng; Kong, Xu; Wang, Wen-Ting; Luo, Zhi-Jian; Wu, Xue-Bing

    2016-01-01

    A small fraction (< 10%) of the SDSS main galaxy (MG) sample has not been targeted with spectroscopy due to the effect of fiber collisions. These galaxies have been compiled into the input catalog of the LAMOST ExtraGAlactic Surveys and named the complementary galaxy sample. In this paper, we introduce this project and status of the spectroscopies associated with the complementary galaxies in the first two years of the LAMOST spectral survey (till Sep. of 2014). Moreover, we present a sample of 1102 galaxy pairs identified from the LAMOST complementary galaxies and SDSS MGs, which are defined as two members that have a projected distance smaller than 100 h −1 70 kpc and a recessional velocity difference smaller than 500 km s −1 . Compared with galaxy pairs that are only selected from SDSS, the LAMOST-SDSS pairs have the advantages of not being biased toward large separations and therefore act as a useful supplement in statistical studies of galaxy interaction and galaxy merging. (paper)

  5. Google Street View as an alternative method to car surveys in large-scale vegetation assessments.

    Science.gov (United States)

    Deus, Ernesto; Silva, Joaquim S; Catry, Filipe X; Rocha, Miguel; Moreira, Francisco

    2015-10-01

    Car surveys (CS) are a common method for assessing the distribution of alien invasive plants. Google Street View (GSV), a free-access web technology where users may experience a virtual travel along roads, has been suggested as a cost-effective alternative to car surveys. We tested if we could replicate the results from a countrywide survey conducted by car in Portugal using GSV as a remote sensing tool, aiming at assessing the distribution of Eucalyptus globulus Labill. wildlings on roadsides adjacent to eucalypt stands. Georeferenced points gathered along CS were used to create road transects visible as lines overlapping the road in GSV environment, allowing surveying the same sampling areas using both methods. This paper presents the results of the comparison between the two methods. Both methods produced similar models of plant abundance, selecting the same explanatory variables, in the same hierarchical order of importance and depicting a similar influence on plant abundance. Even though the GSV model had a lower performance and the GSV survey detected fewer plants, additional variables collected exclusively with GSV improved model performance and provided a new insight into additional factors influencing plant abundance. The survey using GSV required ca. 9 % of the funds and 62 % of the time needed to accomplish the CS. We conclude that GSV may be a cost-effective alternative to CS. We discuss some advantages and limitations of GSV as a survey method. We forecast that GSV may become a widespread tool in road ecology, particularly in large-scale vegetation assessments.

  6. Whither RDS? An investigation of Respondent Driven Sampling as a method of recruiting mainstream marijuana users

    Directory of Open Access Journals (Sweden)

    Cousineau Marie-Marthe

    2010-07-01

    Full Text Available Abstract Background An important challenge in conducting social research of specific relevance to harm reduction programs is locating hidden populations of consumers of substances like cannabis who typically report few adverse or unwanted consequences of their use. Much of the deviant, pathologized perception of drug users is historically derived from, and empirically supported, by a research emphasis on gaining ready access to users in drug treatment or in prison populations with higher incidence of problems of dependence and misuse. Because they are less visible, responsible recreational users of illicit drugs have been more difficult to study. Methods This article investigates Respondent Driven Sampling (RDS as a method of recruiting experienced marijuana users representative of users in the general population. Based on sampling conducted in a multi-city study (Halifax, Montreal, Toronto, and Vancouver, and compared to samples gathered using other research methods, we assess the strengths and weaknesses of RDS recruitment as a means of gaining access to illicit substance users who experience few harmful consequences of their use. Demographic characteristics of the sample in Toronto are compared with those of users in a recent household survey and a pilot study of Toronto where the latter utilized nonrandom self-selection of respondents. Results A modified approach to RDS was necessary to attain the target sample size in all four cities (i.e., 40 'users' from each site. The final sample in Toronto was largely similar, however, to marijuana users in a random household survey that was carried out in the same city. Whereas well-educated, married, whites and females in the survey were all somewhat overrepresented, the two samples, overall, were more alike than different with respect to economic status and employment. Furthermore, comparison with a self-selected sample suggests that (even modified RDS recruitment is a cost-effective way of

  7. The U.S. Geological Survey Geologic Collections Management System (GCMS)—A master catalog and collections management plan for U.S. Geological Survey geologic samples and sample collections

    Science.gov (United States)

    ,

    2015-01-01

    The U.S. Geological Survey (USGS) is widely recognized in the earth science community as possessing extensive collections of earth materials collected by research personnel over the course of its history. In 2006, a Geologic Collections Inventory was conducted within the USGS Geology Discipline to determine the extent and nature of its sample collections, and in 2008, a working group was convened by the USGS National Geologic and Geophysical Data Preservation Program to examine ways in which these collections could be coordinated, cataloged, and made available to researchers both inside and outside the USGS. The charge to this working group was to evaluate the proposition of creating a Geologic Collections Management System (GCMS), a centralized database that would (1) identify all existing USGS geologic collections, regardless of size, (2) create a virtual link among the collections, and (3) provide a way for scientists and other researchers to obtain access to the samples and data in which they are interested. Additionally, the group was instructed to develop criteria for evaluating current collections and to establish an operating plan and set of standard practices for handling, identifying, and managing future sample collections. Policies and procedures promoted by the GCMS would be based on extant best practices established by the National Science Foundation and the Smithsonian Institution. The resulting report—USGS Circular 1410, “The U.S. Geological Survey Geologic Collections Management System (GCMS): A Master Catalog and Collections Management Plan for U.S. Geological Survey Geologic Samples and Sample Collections”—has been developed for sample repositories to be a guide to establishing common practices in the collection, retention, and disposal of geologic research materials throughout the USGS.

  8. Statistical methods for detecting differentially abundant features in clinical metagenomic samples.

    Directory of Open Access Journals (Sweden)

    James Robert White

    2009-04-01

    Full Text Available Numerous studies are currently underway to characterize the microbial communities inhabiting our world. These studies aim to dramatically expand our understanding of the microbial biosphere and, more importantly, hope to reveal the secrets of the complex symbiotic relationship between us and our commensal bacterial microflora. An important prerequisite for such discoveries are computational tools that are able to rapidly and accurately compare large datasets generated from complex bacterial communities to identify features that distinguish them.We present a statistical method for comparing clinical metagenomic samples from two treatment populations on the basis of count data (e.g. as obtained through sequencing to detect differentially abundant features. Our method, Metastats, employs the false discovery rate to improve specificity in high-complexity environments, and separately handles sparsely-sampled features using Fisher's exact test. Under a variety of simulations, we show that Metastats performs well compared to previously used methods, and significantly outperforms other methods for features with sparse counts. We demonstrate the utility of our method on several datasets including a 16S rRNA survey of obese and lean human gut microbiomes, COG functional profiles of infant and mature gut microbiomes, and bacterial and viral metabolic subsystem data inferred from random sequencing of 85 metagenomes. The application of our method to the obesity dataset reveals differences between obese and lean subjects not reported in the original study. For the COG and subsystem datasets, we provide the first statistically rigorous assessment of the differences between these populations. The methods described in this paper are the first to address clinical metagenomic datasets comprising samples from multiple subjects. Our methods are robust across datasets of varied complexity and sampling level. While designed for metagenomic applications, our software

  9. Bibliography of papers, reports, and presentations related to point-sample dimensional measurement methods for machined part evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, J.M. [Sandia National Labs., Livermore, CA (United States). Integrated Manufacturing Systems

    1996-04-01

    The Dimensional Inspection Techniques Specification (DITS) Project is an ongoing effort to produce tools and guidelines for optimum sampling and data analysis of machined parts, when measured using point-sample methods of dimensional metrology. This report is a compilation of results of a literature survey, conducted in support of the DITS. Over 160 citations are included, with author abstracts where available.

  10. Relative efficiency of anuran sampling methods in a restinga habitat (Jurubatiba, Rio de Janeiro, Brazil).

    Science.gov (United States)

    Rocha, C F D; Van Sluys, M; Hatano, F H; Boquimpani-Freitas, L; Marra, R V; Marques, R V

    2004-11-01

    Studies on anurans in restinga habitats are few and, as a result, there is little information on which methods are more efficient for sampling them in this environment. Ten methods are usually used for sampling anuran communities in tropical and sub-tropical areas. In this study we evaluate which methods are more appropriate for this purpose in the restinga environment of Parque Nacional da Restinga de Jurubatiba. We analyzed six methods among those usually used for anuran samplings. For each method, we recorded the total amount of time spent (in min.), the number of researchers involved, and the number of species captured. We calculated a capture efficiency index (time necessary for a researcher to capture an individual frog) in order to make comparable the data obtained. Of the methods analyzed, the species inventory (9.7 min/searcher /ind.- MSI; richness = 6; abundance = 23) and the breeding site survey (9.5 MSI; richness = 4; abundance = 22) were the most efficient. The visual encounter inventory (45.0 MSI) and patch sampling (65.0 MSI) methods were of comparatively lower efficiency restinga, whereas the plot sampling and the pit-fall traps with drift-fence methods resulted in no frog capture. We conclude that there is a considerable difference in efficiency of methods used in the restinga environment and that the complete species inventory method is highly efficient for sampling frogs in the restinga studied and may be so in other restinga environments. Methods that are usually efficient in forested areas seem to be of little value in open restinga habitats.

  11. Relative efficiency of anuran sampling methods in a restinga habitat (Jurubatiba, Rio de Janeiro, Brazil

    Directory of Open Access Journals (Sweden)

    C. F. D. Rocha

    Full Text Available Studies on anurans in restinga habitats are few and, as a result, there is little information on which methods are more efficient for sampling them in this environment. Ten methods are usually used for sampling anuran communities in tropical and sub-tropical areas. In this study we evaluate which methods are more appropriate for this purpose in the restinga environment of Parque Nacional da Restinga de Jurubatiba. We analyzed six methods among those usually used for anuran samplings. For each method, we recorded the total amount of time spent (in min., the number of researchers involved, and the number of species captured. We calculated a capture efficiency index (time necessary for a researcher to capture an individual frog in order to make comparable the data obtained. Of the methods analyzed, the species inventory (9.7 min/searcher /ind.- MSI; richness = 6; abundance = 23 and the breeding site survey (9.5 MSI; richness = 4; abundance = 22 were the most efficient. The visual encounter inventory (45.0 MSI and patch sampling (65.0 MSI methods were of comparatively lower efficiency restinga, whereas the plot sampling and the pit-fall traps with drift-fence methods resulted in no frog capture. We conclude that there is a considerable difference in efficiency of methods used in the restinga environment and that the complete species inventory method is highly efficient for sampling frogs in the restinga studied and may be so in other restinga environments. Methods that are usually efficient in forested areas seem to be of little value in open restinga habitats.

  12. An improved sampling method of complex network

    Science.gov (United States)

    Gao, Qi; Ding, Xintong; Pan, Feng; Li, Weixing

    2014-12-01

    Sampling subnet is an important topic of complex network research. Sampling methods influence the structure and characteristics of subnet. Random multiple snowball with Cohen (RMSC) process sampling which combines the advantages of random sampling and snowball sampling is proposed in this paper. It has the ability to explore global information and discover the local structure at the same time. The experiments indicate that this novel sampling method could keep the similarity between sampling subnet and original network on degree distribution, connectivity rate and average shortest path. This method is applicable to the situation where the prior knowledge about degree distribution of original network is not sufficient.

  13. 36 CFR 9.42 - Well records and reports, plots and maps, samples, tests and surveys.

    Science.gov (United States)

    2010-07-01

    ... Well records and reports, plots and maps, samples, tests and surveys. Any technical data gathered... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Well records and reports, plots and maps, samples, tests and surveys. 9.42 Section 9.42 Parks, Forests, and Public Property...

  14. On Survey Data Analysis in Corporate Finance

    OpenAIRE

    Serita, Toshio

    2008-01-01

    Recently, survey data analysis has emerged as a new method for testing hypotheses andfor clarifying the relative importance of different factors in corporate finance decisions. This paper investigates the advantages and drawbacks of survey data analysis, methodology of survey data analysis such as questionnaire design, and analytical methods for survey data, incomparison with traditional large sample analysis. We show that survey data analysis does not replace traditional large sample analysi...

  15. Comparison of sampling methods for animal manure

    NARCIS (Netherlands)

    Derikx, P.J.L.; Ogink, N.W.M.; Hoeksma, P.

    1997-01-01

    Currently available and recently developed sampling methods for slurry and solid manure were tested for bias and reproducibility in the determination of total phosphorus and nitrogen content of samples. Sampling methods were based on techniques in which samples were taken either during loading from

  16. Methodology of the fasting sub-sample from the Mexican Health Survey, 2000 Metodología de la submuestra de suero de la Encuesta Nacional de Salud 2000

    OpenAIRE

    Simón Barquera; Citlalli Carrión; Ismael Campos; Juan Espinosa; Juan Rivera; Gustavo Olaiz-Fernández

    2007-01-01

    OBJECTIVE: To report the comparative results of the sub-sample of fasting adults selected for the biochemical measurement of cardiovascular risk factors and the rest of the Mexican Health Survey (MHS) (2000) participants. MATERIAL AND METHODS: The nationally representative, cross-sectional Mexican Health Survey (2000) was analyzed. Survey participants reporting a fasting state period of 9- to 12-h were included in a sub-sample (n= 2 535) and compared with all other participants (n= 41 126). P...

  17. Pilot studies for the North American Soil Geochemical Landscapes Project - Site selection, sampling protocols, analytical methods, and quality control protocols

    Science.gov (United States)

    Smith, D.B.; Woodruff, L.G.; O'Leary, R. M.; Cannon, W.F.; Garrett, R.G.; Kilburn, J.E.; Goldhaber, M.B.

    2009-01-01

    In 2004, the US Geological Survey (USGS) and the Geological Survey of Canada sampled and chemically analyzed soils along two transects across Canada and the USA in preparation for a planned soil geochemical survey of North America. This effort was a pilot study to test and refine sampling protocols, analytical methods, quality control protocols, and field logistics for the continental survey. A total of 220 sample sites were selected at approximately 40-km intervals along the two transects. The ideal sampling protocol at each site called for a sample from a depth of 0-5 cm and a composite of each of the O, A, and C horizons. The Ca, Fe, K, Mg, Na, S, Ti, Ag, As, Ba, Be, Bi, Cd, Ce, Co, Cr, Cs, Cu, Ga, In, La, Li, Mn, Mo, Nb, Ni, P, Pb, Rb, Sb, Sc, Sn, Sr, Te, Th, Tl, U, V, W, Y, and Zn by inductively coupled plasma-mass spectrometry and inductively coupled plasma-atomic emission spectrometry following a near-total digestion in a mixture of HCl, HNO3, HClO4, and HF. Separate methods were used for Hg, Se, total C, and carbonate-C on this same size fraction. Only Ag, In, and Te had a large percentage of concentrations below the detection limit. Quality control (QC) of the analyses was monitored at three levels: the laboratory performing the analysis, the USGS QC officer, and the principal investigator for the study. This level of review resulted in an average of one QC sample for every 20 field samples, which proved to be minimally adequate for such a large-scale survey. Additional QC samples should be added to monitor within-batch quality to the extent that no more than 10 samples are analyzed between a QC sample. Only Cr (77%), Y (82%), and Sb (80%) fell outside the acceptable limits of accuracy (% recovery between 85 and 115%) because of likely residence in mineral phases resistant to the acid digestion. A separate sample of 0-5-cm material was collected at each site for determination of organic compounds. A subset of 73 of these samples was analyzed for a suite of

  18. BMAA extraction of cyanobacteria samples: which method to choose?

    Science.gov (United States)

    Lage, Sandra; Burian, Alfred; Rasmussen, Ulla; Costa, Pedro Reis; Annadotter, Heléne; Godhe, Anna; Rydberg, Sara

    2016-01-01

    β-N-Methylamino-L-alanine (BMAA), a neurotoxin reportedly produced by cyanobacteria, diatoms and dinoflagellates, is proposed to be linked to the development of neurological diseases. BMAA has been found in aquatic and terrestrial ecosystems worldwide, both in its phytoplankton producers and in several invertebrate and vertebrate organisms that bioaccumulate it. LC-MS/MS is the most frequently used analytical technique in BMAA research due to its high selectivity, though consensus is lacking as to the best extraction method to apply. This study accordingly surveys the efficiency of three extraction methods regularly used in BMAA research to extract BMAA from cyanobacteria samples. The results obtained provide insights into possible reasons for the BMAA concentration discrepancies in previous publications. In addition and according to the method validation guidelines for analysing cyanotoxins, the TCA protein precipitation method, followed by AQC derivatization and LC-MS/MS analysis, is now validated for extracting protein-bound (after protein hydrolysis) and free BMAA from cyanobacteria matrix. BMAA biological variability was also tested through the extraction of diatom and cyanobacteria species, revealing a high variance in BMAA levels (0.0080-2.5797 μg g(-1) DW).

  19. Moving beyond Traditional Methods of Survey Validation

    Science.gov (United States)

    Maul, Andrew

    2017-01-01

    In his focus article, "Rethinking Traditional Methods of Survey Validation," published in this issue of "Measurement: Interdisciplinary Research and Perspectives," Andrew Maul wrote that it is commonly believed that self-report, survey-based instruments can be used to measure a wide range of psychological attributes, such as…

  20. Sampling methods for pasture, soil and deposition for radioactivity emergency preparedness in the Nordic countries

    International Nuclear Information System (INIS)

    Isaksson, M.

    2002-01-01

    The aim of this work was to compare sampling techniques for pasture, soil and deposition, planned for radioactivity surveillance in emergency situations in the Nordic countries. The basis of the survey was a questionnaire, sent to radiation protection authorities and laboratories. Sampling of pasture is performed with a cutting height between 1 and 5 cm above the ground from an area of about 1 m 2 . The sampling plots are usually randomly positioned. Soil samples, 3 to 20 cores in various patterns, are generally taken by a corer of varying diameter. For deposition sampling, precipitation collectors of different sizes are used. When comparing results, the differences between laboratories should be borne in mind so that proper corrections can be made. It is, however, important to consider that, especially in an emergency situation, the use of standardised methods may worsen the results if these methods are not part of the daily work. (orig.)

  1. Hard-to-reach populations of men who have sex with men and sex workers: a systematic review on sampling methods.

    Science.gov (United States)

    Barros, Ana B; Dias, Sonia F; Martins, Maria Rosario O

    2015-10-30

    In public health, hard-to-reach populations are often recruited by non-probabilistic sampling methods that produce biased results. In order to overcome this, several sampling methods have been improved and developed in the last years. The aim of this systematic review was to identify all current methods used to survey most-at-risk populations of men who have sex with men and sex workers. The review also aimed to assess if there were any relations between the study populations and the sampling methods used to recruit them. Lastly, we wanted to assess if the number of publications originated in middle and low human development (MLHD) countries had been increasing in the last years. A systematic review was conducted using electronic databases and a total of 268 published studies were included in the analysis. In this review, 11 recruitment methods were identified. Semi-probabilistic methods were used most commonly to survey men who have sex with men, and the use of the Internet was the method that gathered more respondents. We found that female sex workers were more frequently recruited through non-probabilistic methods than men who have sex with men (odds = 2.2; p review identified 11 methods used to sample men who have sex with men and female sex workers. There is an association between the type of sampling method and the population being studied. The number of studies based in middle and low human development countries has increased in the last 6 years of this study.

  2. Interest of LQAS method in a survey of HTLV-I infection in Benin (West Africa).

    Science.gov (United States)

    Houinato, Dismand; Preux, Pierre-Marie; Charriere, Bénédicte; Massit, Bruno; Avodé, Gilbert; Denis, François; Dumas, Michel; Boutros-Toni, Fernand; Salamon, Roger

    2002-02-01

    HTLV-I is heterogeneously distributed in Sub-Saharan Africa. Traditional survey methods as cluster sampling could provide information for a country or region of interest. However, they cannot identify small areas with higher prevalences of infection to help in the health policy planning. Identification of such areas could be done by a Lot Quality Assurance Sampling (LQAS) method, which is currently used in industry to identify a poor performance in assembly lines. The LQAS method was used in Atacora (Northern Benin) between March and May 1998 to identify areas with a HTLV-I seroprevalence higher than 4%. Sixty-five subjects were randomly selected in each of 36 communes (lots) of this department. Lots were classified as unacceptable when the sample contained at least one positive subject. The LQAS method identified 25 (69.4 %) communes with a prevalence higher than 4%. Using stratified sampling theory, the overall HTLV-I seroprevalence was 4.5% (95% CI: 3.6-5.4%). These data show the interest of LQAS method application under field conditions to detect clusters of infection.

  3. Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of the total phosphorus by a Kjeldahl digestion method and an automated colorimetric finish that includes dialysis

    Science.gov (United States)

    Patton, Charles J.; Truitt, Earl P.

    1992-01-01

    A method to determine total phosphorus (TP) in the same digests prepared for total Kjeldahl nitrogen (TKN) determinations is desribed. The batch, high-temperature (block digester), HG(II)-catalyzed digestion step is similar to U.S. Geological Survey methods I-2552-85/I-4552-85 and U.S. Environmental Protection Agency method 365.4 except that sample and reagent volumes are halved. Prepared digests are desolvated at 220 degrees Celsius and digested at 370 degrees Celsius in separate block digesters set at these temperatures, rather than in a single, temperature-programmed block digester. This approach is used in the method escribed here, which permits 40 calibrants, reference waters, and smaples to be digested and resolvated in about an hour. Orthophosphate ions originally present in samples, along with those released during the digestion step, are determined colorimetrically at a rate of 90 tests per hour by an automated version of the phosphoantimonylmolybdenum blue procedure. About 100 microliters of digest are required per determination. The upper concentration limit is 2 milligrams per liter (mg/L) with a method detection limt of 0.01 mg/L. Repeatability for a sample containing approximately 1.6 mg/L of TP in a high suspended-solids matrix is 0.7 percent. Between-day precision for the same sample is 5.0 percent. A dialyzer in the air-segmented continuous flow analyzer provides on-line digest cleanup, eliminated particulates that otherwise would interfere in the colorimetric finish. An single-channel analyzer can process the resolvated digests from two pairs of block digesters each hour. Paired t-test analysis of TP concentrations for approximately 1,600 samples determined by the new method (U.S. Geologial Survey methods I-2610-91 and I-4610-91) and the old method (U.S. Geological Survey methods I-2600-85 and I-4600-85) revealed positive bias in the former of 0.02 to 0.04 mg/L for surface-water samples in agreement with previous studies. Concentrations of total

  4. Survey of statistical and sampling needs for environmental monitoring of commercial low-level radioactive waste disposal facilities

    International Nuclear Information System (INIS)

    Eberhardt, L.L.; Thomas, J.M.

    1986-07-01

    This project was designed to develop guidance for implementing 10 CFR Part 61 and to determine the overall needs for sampling and statistical work in characterizing, surveying, monitoring, and closing commercial low-level waste sites. When cost-effectiveness and statistical reliability are of prime importance, then double sampling, compositing, and stratification (with optimal allocation) are identified as key issues. If the principal concern is avoiding questionable statistical practice, then the applicability of kriging (for assessing spatial pattern), methods for routine monitoring, and use of standard textbook formulae in reporting monitoring results should be reevaluated. Other important issues identified include sampling for estimating model parameters and the use of data from left-censored (less than detectable limits) distributions

  5. Sampling effects on the identification of roadkill hotspots: Implications for survey design.

    Science.gov (United States)

    Santos, Sara M; Marques, J Tiago; Lourenço, André; Medinas, Denis; Barbosa, A Márcia; Beja, Pedro; Mira, António

    2015-10-01

    Although locating wildlife roadkill hotspots is essential to mitigate road impacts, the influence of study design on hotspot identification remains uncertain. We evaluated how sampling frequency affects the accuracy of hotspot identification, using a dataset of vertebrate roadkills (n = 4427) recorded over a year of daily surveys along 37 km of roads. "True" hotspots were identified using this baseline dataset, as the 500-m segments where the number of road-killed vertebrates exceeded the upper 95% confidence limit of the mean, assuming a Poisson distribution of road-kills per segment. "Estimated" hotspots were identified likewise, using datasets representing progressively lower sampling frequencies, which were produced by extracting data from the baseline dataset at appropriate time intervals (1-30 days). Overall, 24.3% of segments were "true" hotspots, concentrating 40.4% of roadkills. For different groups, "true" hotspots accounted from 6.8% (bats) to 29.7% (small birds) of road segments, concentrating from 60% (lizards, lagomorphs, carnivores) of roadkills. Spatial congruence between "true" and "estimated" hotspots declined rapidly with increasing time interval between surveys, due primarily to increasing false negatives (i.e., missing "true" hotspots). There were also false positives (i.e., wrong "estimated" hotspots), particularly at low sampling frequencies. Spatial accuracy decay with increasing time interval between surveys was higher for smaller-bodied (amphibians, reptiles, small birds, small mammals) than for larger-bodied species (birds of prey, hedgehogs, lagomorphs, carnivores). Results suggest that widely used surveys at weekly or longer intervals may produce poor estimates of roadkill hotspots, particularly for small-bodied species. Surveying daily or at two-day intervals may be required to achieve high accuracy in hotspot identification for multiple species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Survey Research: Methods, Issues and the Future

    Science.gov (United States)

    Brewer, Ernest W.; Torrisi-Steele, Geraldine; Wang, Victor C. X.

    2015-01-01

    Survey research is prevalent among many professional fields. Both cost effective and time efficient, this method of research is commonly used for the purposes of gaining insight into the attitudes, thoughts, and opinions of populations. Additionally, because there are several types of survey research designs and data collection instruments, the…

  7. 7 CFR 29.110 - Method of sampling.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Method of sampling. 29.110 Section 29.110 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.110 Method of sampling. In sampling tobacco...

  8. A comparison of turtle sampling methods in a small lake in Standing Stone State Park, Overton County, Tennessee

    Science.gov (United States)

    Weber, A.; Layzer, James B.

    2011-01-01

    We used basking traps and hoop nets to sample turtles in Standing Stone Lake at 2-week intervals from May to November 2006. In alternate weeks, we conducted visual basking surveys. We collected and observed four species of turtles: spiny softshell (Apalone spinifera), northern map turtle (Graptemys geographica), pond slider (Trachernys scripta), and snapping turtle (Chelydra serpentina). Relative abundances varied greatly among sampling methods. To varying degrees, all methods were species selective. Population estimates from mark and recaptures of three species, basking counts, and hoop net catches indicated that pond sliders were the most abundant species, but northern map turtles were 8× more abundant than pond sliders in basking trap catches. We saw relatively few snapping turtles basking even though population estimates indicated they were the second most abundant species. Populations of all species were dominated by adult individuals. Sex ratios of three species differed significantly from 1:1. Visual surveys were the most efficient method for determining the presence of species, but capture methods were necessary to obtain size and sex data.

  9. Uniform Sampling Table Method and its Applications II--Evaluating the Uniform Sampling by Experiment.

    Science.gov (United States)

    Chen, Yibin; Chen, Jiaxi; Chen, Xuan; Wang, Min; Wang, Wei

    2015-01-01

    A new method of uniform sampling is evaluated in this paper. The items and indexes were adopted to evaluate the rationality of the uniform sampling. The evaluation items included convenience of operation, uniformity of sampling site distribution, and accuracy and precision of measured results. The evaluation indexes included operational complexity, occupation rate of sampling site in a row and column, relative accuracy of pill weight, and relative deviation of pill weight. They were obtained from three kinds of drugs with different shape and size by four kinds of sampling methods. Gray correlation analysis was adopted to make the comprehensive evaluation by comparing it with the standard method. The experimental results showed that the convenience of uniform sampling method was 1 (100%), odds ratio of occupation rate in a row and column was infinity, relative accuracy was 99.50-99.89%, reproducibility RSD was 0.45-0.89%, and weighted incidence degree exceeded the standard method. Hence, the uniform sampling method was easy to operate, and the selected samples were distributed uniformly. The experimental results demonstrated that the uniform sampling method has good accuracy and reproducibility, which can be put into use in drugs analysis.

  10. Comparability among four invertebrate sampling methods and two multimetric indexes, Fountain Creek Basin, Colorado, 2010–2012

    Science.gov (United States)

    Bruce, James F.; Roberts, James J.; Zuellig, Robert E.

    2018-05-24

    The U.S. Geological Survey (USGS), in cooperation with Colorado Springs City Engineering and Colorado Springs Utilities, analyzed previously collected invertebrate data to determine the comparability among four sampling methods and two versions (2010 and 2017) of the Colorado Benthic Macroinvertebrate Multimetric Index (MMI). For this study, annual macroinvertebrate samples were collected concurrently (in space and time) at 15 USGS surface-water gaging stations in the Fountain Creek Basin from 2010 to 2012 using four sampling methods. The USGS monitoring project in the basin uses two of the methods and the Colorado Department of Public Health and Environment recommends the other two. These methods belong to two distinct sample types, one that targets single habitats and one that targets multiple habitats. The study results indicate that there are significant differences in MMI values obtained from the single-habitat and multihabitat sample types but methods from each program within each sample type produced comparable values. This study also determined that MMI values calculated by different versions of the Colorado Benthic Macroinvertebrate MMI are indistinguishable. This indicates that the Colorado Department of Public Health and Environment methods are comparable with the USGS monitoring project methods for single-habitat and multihabitat sample types. This report discusses the direct application of the study results to inform the revision of the existing USGS monitoring project in the Fountain Creek Basin.

  11. 19 CFR 151.83 - Method of sampling.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Method of sampling. 151.83 Section 151.83 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) EXAMINATION, SAMPLING, AND TESTING OF MERCHANDISE Cotton § 151.83 Method of sampling. For...

  12. Gathering Opinions on Depression Information Needs and Preferences: Samples and Opinions in Clinic Versus Web-Based Surveys.

    Science.gov (United States)

    Bernstein, Matthew T; Walker, John R; Sexton, Kathryn A; Katz, Alan; Beatie, Brooke E

    2017-04-24

    There has been limited research on the information needs and preferences of the public concerning treatment for depression. Very little research is available comparing samples and opinions when recruitment for surveys is done over the Web as opposed to a personal invitation to complete a paper survey. This study aimed to (1) to explore information needs and preferences among members of the public and (2) compare Clinic and Web samples on sample characteristics and survey findings. Web survey participants were recruited with a notice on three self-help association websites (N=280). Clinic survey participants were recruited by a research assistant in the waiting rooms of a family medicine clinic and a walk-in medical clinic (N=238) and completed a paper version of the survey. The Clinic and Web samples were similar in age (39.0 years, SD 13.9 vs 40.2 years, SD 12.5, respectively), education, and proportion in full time employment. The Clinic sample was more diverse in demographic characteristics and closer to the demographic characteristics of the region (Winnipeg, Canada) with a higher proportion of males (102/238 [42.9%] vs 45/280 [16.1%]) and nonwhites (Aboriginal, Asian, and black) (69/238 [29.0%] vs 39/280 [13.9%]). The Web sample reported a higher level of emotional distress and had more previous psychological (224/280 [80.0%] vs 83/238 [34.9%]) and pharmacological (202/280 [72.1%] vs 57/238 [23.9%]) treatment. In terms of opinions, most respondents in both settings saw information on a wide range of topics around depression treatment as very important including information about treatment choices, effectiveness of treatment, how long it takes treatment to work, how long treatment continues, what happens when treatment stops, advantages and disadvantages of treatments, and potential side effects. Females, respondents with a white background, and those who had received or felt they would have benefited from therapy in the past saw more information topics as very

  13. ALARA ASSESSMENT OF SETTLER SLUDGE SAMPLING METHODS

    International Nuclear Information System (INIS)

    Nelsen, L.A.

    2009-01-01

    The purpose of this assessment is to compare underwater and above water settler sludge sampling methods to determine if the added cost for underwater sampling for the sole purpose of worker dose reductions is justified. Initial planning for sludge sampling included container, settler and knock-out-pot (KOP) sampling. Due to the significantly higher dose consequence of KOP sludge, a decision was made to sample KOP underwater to achieve worker dose reductions. Additionally, initial plans were to utilize the underwater sampling apparatus for settler sludge. Since there are no longer plans to sample KOP sludge, the decision for underwater sampling for settler sludge needs to be revisited. The present sampling plan calls for spending an estimated $2,500,000 to design and construct a new underwater sampling system (per A21 C-PL-001 RevOE). This evaluation will compare and contrast the present method of above water sampling to the underwater method that is planned by the Sludge Treatment Project (STP) and determine if settler samples can be taken using the existing sampling cart (with potentially minor modifications) while maintaining doses to workers As Low As Reasonably Achievable (ALARA) and eliminate the need for costly redesigns, testing and personnel retraining

  14. ALARA ASSESSMENT OF SETTLER SLUDGE SAMPLING METHODS

    Energy Technology Data Exchange (ETDEWEB)

    NELSEN LA

    2009-01-30

    The purpose of this assessment is to compare underwater and above water settler sludge sampling methods to determine if the added cost for underwater sampling for the sole purpose of worker dose reductions is justified. Initial planning for sludge sampling included container, settler and knock-out-pot (KOP) sampling. Due to the significantly higher dose consequence of KOP sludge, a decision was made to sample KOP underwater to achieve worker dose reductions. Additionally, initial plans were to utilize the underwater sampling apparatus for settler sludge. Since there are no longer plans to sample KOP sludge, the decision for underwater sampling for settler sludge needs to be revisited. The present sampling plan calls for spending an estimated $2,500,000 to design and construct a new underwater sampling system (per A21 C-PL-001 RevOE). This evaluation will compare and contrast the present method of above water sampling to the underwater method that is planned by the Sludge Treatment Project (STP) and determine if settler samples can be taken using the existing sampling cart (with potentially minor modifications) while maintaining doses to workers As Low As Reasonably Achievable (ALARA) and eliminate the need for costly redesigns, testing and personnel retraining.

  15. Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio.

    Directory of Open Access Journals (Sweden)

    João Fabrício Mota Rodrigues

    Full Text Available Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population's sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns.

  16. Differences in Movement Pattern and Detectability between Males and Females Influence How Common Sampling Methods Estimate Sex Ratio.

    Science.gov (United States)

    Rodrigues, João Fabrício Mota; Coelho, Marco Túlio Pacheco

    2016-01-01

    Sampling the biodiversity is an essential step for conservation, and understanding the efficiency of sampling methods allows us to estimate the quality of our biodiversity data. Sex ratio is an important population characteristic, but until now, no study has evaluated how efficient are the sampling methods commonly used in biodiversity surveys in estimating the sex ratio of populations. We used a virtual ecologist approach to investigate whether active and passive capture methods are able to accurately sample a population's sex ratio and whether differences in movement pattern and detectability between males and females produce biased estimates of sex-ratios when using these methods. Our simulation allowed the recognition of individuals, similar to mark-recapture studies. We found that differences in both movement patterns and detectability between males and females produce biased estimates of sex ratios. However, increasing the sampling effort or the number of sampling days improves the ability of passive or active capture methods to properly sample sex ratio. Thus, prior knowledge regarding movement patterns and detectability for species is important information to guide field studies aiming to understand sex ratio related patterns.

  17. An assessment of Lot Quality Assurance Sampling to evaluate malaria outcome indicators: extending malaria indicator surveys.

    Science.gov (United States)

    Biedron, Caitlin; Pagano, Marcello; Hedt, Bethany L; Kilian, Albert; Ratcliffe, Amy; Mabunda, Samuel; Valadez, Joseph J

    2010-02-01

    Large investments and increased global prioritization of malaria prevention and treatment have resulted in greater emphasis on programme monitoring and evaluation (M&E) in many countries. Many countries currently use large multistage cluster sample surveys to monitor malaria outcome indicators on a regional and national level. However, these surveys often mask local-level variability important to programme management. Lot Quality Assurance Sampling (LQAS) has played a valuable role for local-level programme M&E. If incorporated into these larger surveys, it would provide a comprehensive M&E plan at little, if any, extra cost. The Mozambique Ministry of Health conducted a Malaria Indicator Survey (MIS) in June and July 2007. We applied LQAS classification rules to the 345 sampled enumeration areas to demonstrate identifying high- and low-performing areas with respect to two malaria program indicators-'household possession of any bednet' and 'household possession of any insecticide-treated bednet (ITN)'. As shown by the MIS, no province in Mozambique achieved the 70% coverage target for household possession of bednets or ITNs. By applying LQAS classification rules to the data, we identify 266 of the 345 enumeration areas as having bednet coverage severely below the 70% target. An additional 73 were identified with low ITN coverage. This article demonstrates the feasibility of integrating LQAS into multistage cluster sampling surveys and using these results to support a comprehensive national, regional and local programme M&E system. Furthermore, in the recommendations we outlined how to integrate the Large Country-LQAS design into macro-surveys while still obtaining results available through current sampling practices.

  18. Discussion on the source survey method in a natural evaporation pond

    International Nuclear Information System (INIS)

    Dai Xiaoshu; Fan Chengrong; Fu Yunshan

    2014-01-01

    A natural evaporation pond intended to be decommissioned. The survey of the pond focused on investigating radioactive contamination distribution and estimating the total amount of deposits in the pond, in order to provide support for subsequent decommissioning activities. Based on the source survey in the pond, this paper introduced how to implement radiation measurements and sampling (such as water and sediment) in the water. The movable work platform was built on the pond to facilitate sampling and measurement. In addition, a sludge sampler had been designed so as to accurately determine the amount of sampling and its depth. This paper also described the distribution of sampling points. (authors)

  19. Nonprobability Web Surveys to Measure Sexual Behaviors and Attitudes in the General Population: A Comparison With a Probability Sample Interview Survey

    Science.gov (United States)

    Burkill, Sarah; Couper, Mick P; Conrad, Frederick; Clifton, Soazig; Tanton, Clare; Phelps, Andrew; Datta, Jessica; Mercer, Catherine H; Sonnenberg, Pam; Prah, Philip; Mitchell, Kirstin R; Wellings, Kaye; Johnson, Anne M; Copas, Andrew J

    2014-01-01

    Background Nonprobability Web surveys using volunteer panels can provide a relatively cheap and quick alternative to traditional health and epidemiological surveys. However, concerns have been raised about their representativeness. Objective The aim was to compare results from different Web panels with a population-based probability sample survey (n=8969 aged 18-44 years) that used computer-assisted self-interview (CASI) for sensitive behaviors, the third British National Survey of Sexual Attitudes and Lifestyles (Natsal-3). Methods Natsal-3 questions were included on 4 nonprobability Web panel surveys (n=2000 to 2099), 2 using basic quotas based on age and sex, and 2 using modified quotas based on additional variables related to key estimates. Results for sociodemographic characteristics were compared with external benchmarks and for sexual behaviors and opinions with Natsal-3. Odds ratios (ORs) were used to express differences between the benchmark data and each survey for each variable of interest. A summary measure of survey performance was the average absolute OR across variables. Another summary measure was the number of key estimates for which the survey differed significantly (at the 5% level) from the benchmarks. Results For sociodemographic variables, the Web surveys were less representative of the general population than Natsal-3. For example, for men, the average absolute OR for Natsal-3 was 1.14, whereas for the Web surveys the average absolute ORs ranged from 1.86 to 2.30. For all Web surveys, approximately two-thirds of the key estimates of sexual behaviors were different from Natsal-3 and the average absolute ORs ranged from 1.32 to 1.98. Differences were appreciable even for questions asked by CASI in Natsal-3. No single Web survey performed consistently better than any other did. Modified quotas slightly improved results for men, but not for women. Conclusions Consistent with studies from other countries on less sensitive topics, volunteer Web

  20. Survey research.

    Science.gov (United States)

    Alderman, Amy K; Salem, Barbara

    2010-10-01

    Survey research is a unique methodology that can provide insight into individuals' perspectives and experiences and can be collected on a large population-based sample. Specifically, in plastic surgery, survey research can provide patients and providers with accurate and reproducible information to assist with medical decision-making. When using survey methods in research, researchers should develop a conceptual model that explains the relationships of the independent and dependent variables. The items of the survey are of primary importance. Collected data are only useful if they accurately measure the concepts of interest. In addition, administration of the survey must follow basic principles to ensure an adequate response rate and representation of the intended target sample. In this article, the authors review some general concepts important for successful survey research and discuss the many advantages this methodology has for obtaining limitless amounts of valuable information.

  1. Web-based surveys as an alternative to traditional mail methods.

    Science.gov (United States)

    Fleming, Christopher M; Bowden, Mark

    2009-01-01

    Environmental economists have long used surveys to gather information about people's preferences. A recent innovation in survey methodology has been the advent of web-based surveys. While the Internet appears to offer a promising alternative to conventional survey administration modes, concerns exist over potential sampling biases associated with web-based surveys and the effect these may have on valuation estimates. This paper compares results obtained from a travel cost questionnaire of visitors to Fraser Island, Australia, that was conducted using two alternate survey administration modes; conventional mail and web-based. It is found that response rates and the socio-demographic make-up of respondents to the two survey modes are not statistically different. Moreover, both modes yield similar consumer surplus estimates.

  2. Standard methods for sampling and sample preparation for gamma spectroscopy

    International Nuclear Information System (INIS)

    Taskaeva, M.; Taskaev, E.; Nikolov, P.

    1993-01-01

    The strategy for sampling and sample preparation is outlined: necessary number of samples; analysis and treatment of the results received; quantity of the analysed material according to the radionuclide concentrations and analytical methods; the minimal quantity and kind of the data needed for making final conclusions and decisions on the base of the results received. This strategy was tested in gamma spectroscopic analysis of radionuclide contamination of the region of Eleshnitsa Uranium Mines. The water samples was taken and stored according to the ASTM D 3370-82. The general sampling procedures were in conformity with the recommendations of ISO 5667. The radionuclides was concentrated by coprecipitation with iron hydroxide and ion exchange. The sampling of soil samples complied with the rules of ASTM C 998, and their sample preparation - with ASTM C 999. After preparation the samples were sealed hermetically and measured. (author)

  3. Sampling bee communities using pan traps: alternative methods increase sample size

    Science.gov (United States)

    Monitoring of the status of bee populations and inventories of bee faunas require systematic sampling. Efficiency and ease of implementation has encouraged the use of pan traps to sample bees. Efforts to find an optimal standardized sampling method for pan traps have focused on pan trap color. Th...

  4. New adaptive sampling method in particle image velocimetry

    International Nuclear Information System (INIS)

    Yu, Kaikai; Xu, Jinglei; Tang, Lan; Mo, Jianwei

    2015-01-01

    This study proposes a new adaptive method to enable the number of interrogation windows and their positions in a particle image velocimetry (PIV) image interrogation algorithm to become self-adapted according to the seeding density. The proposed method can relax the constraint of uniform sampling rate and uniform window size commonly adopted in the traditional PIV algorithm. In addition, the positions of the sampling points are redistributed on the basis of the spring force generated by the sampling points. The advantages include control of the number of interrogation windows according to the local seeding density and smoother distribution of sampling points. The reliability of the adaptive sampling method is illustrated by processing synthetic and experimental images. The synthetic example attests to the advantages of the sampling method. Compared with that of the uniform interrogation technique in the experimental application, the spatial resolution is locally enhanced when using the proposed sampling method. (technical design note)

  5. A simulation study of how simple mark-recapture methods can be combined with destructive sub-sampling to facilitate surveys of flying insects

    DEFF Research Database (Denmark)

    Nachman, Gøsta Støger; Skovgård, Henrik; Pedersen, Henrik Skovgård

    2012-01-01

    Mark-recapture techniques are used for studies of animal populations. With only three sampling occasions, both Bailey's triple-catch (BTC) and Jolly-Seber's (J-S) stochastic method can be applied. As marking and handling of fragile organisms may harm them, and thereby affect their chances of being...... to compare the subsampling method with the ordinary mark-recapture methods. Model-generated populations were sampled with and without subsampling to provide estimates of population size, loss, and dilution rates. The estimated parameters were compared with their true values to identify biases associated...... with the sampling methods, using 81 different combinations of population size, dilution rate, loss rate, and sampling effort. Each combination was replicated 1,000 times. In no cases did subsampling perform more poorly than the ordinary methods. J-S was slightly more accurate than BTC to estimate the population...

  6. A New Automated Method and Sample Data Flow for Analysis of Volatile Nitrosamines in Human Urine*

    Science.gov (United States)

    Hodgson, James A.; Seyler, Tiffany H.; McGahee, Ernest; Arnstein, Stephen; Wang, Lanqing

    2016-01-01

    Volatile nitrosamines (VNAs) are a group of compounds classified as probable (group 2A) and possible (group 2B) carcinogens in humans. Along with certain foods and contaminated drinking water, VNAs are detected at high levels in tobacco products and in both mainstream and sidestream smoke. Our laboratory monitors six urinary VNAs—N-nitrosodimethylamine (NDMA), N-nitrosomethylethylamine (NMEA), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine (NPIP), N-nitrosopyrrolidine (NPYR), and N-nitrosomorpholine (NMOR)—using isotope dilution GC-MS/MS (QQQ) for large population studies such as the National Health and Nutrition Examination Survey (NHANES). In this paper, we report for the first time a new automated sample preparation method to more efficiently quantitate these VNAs. Automation is done using Hamilton STAR™ and Caliper Staccato™ workstations. This new automated method reduces sample preparation time from 4 hours to 2.5 hours while maintaining precision (inter-run CV < 10%) and accuracy (85% - 111%). More importantly this method increases sample throughput while maintaining a low limit of detection (<10 pg/mL) for all analytes. A streamlined sample data flow was created in parallel to the automated method, in which samples can be tracked from receiving to final LIMs output with minimal human intervention, further minimizing human error in the sample preparation process. This new automated method and the sample data flow are currently applied in bio-monitoring of VNAs in the US non-institutionalized population NHANES 2013-2014 cycle. PMID:26949569

  7. Obscured AGN at z similar to 1 from the zCOSMOS-Bright Survey : I. Selection and optical properties of a [Ne v]-selected sample

    NARCIS (Netherlands)

    Mignoli, M.; Vignali, C.; Gilli, R.; Comastri, A.; Zamorani, G.; Bolzonella, M.; Bongiorno, A.; Lamareille, F.; Nair, P.; Pozzetti, L.; Lilly, S. J.; Carollo, C. M.; Contini, T.; Kneib, J. -P.; Le Fevre, O.; Mainieri, V.; Renzini, A.; Scodeggio, M.; Bardelli, S.; Caputi, K.; Cucciati, O.; de la Torre, S.; de Ravel, L.; Franzetti, P.; Garilli, B.; Iovino, A.; Kampczyk, P.; Knobel, C.; Kovac, K.; Le Borgne, J. -F.; Le Brun, V.; Maier, C.; Pello, R.; Peng, Y.; Montero, E. Perez; Presotto, V.; Silverman, J. D.; Tanaka, M.; Tasca, L.; Tresse, L.; Vergani, D.; Zucca, E.; Bordoloi, R.; Cappi, A.; Cimatti, A.; Koekemoer, A. M.; McCracken, H. J.; Moresco, M.; Welikala, N.

    Aims. The application of multi-wavelength selection techniques is essential for obtaining a complete and unbiased census of active galactic nuclei (AGN). We present here a method for selecting z similar to 1 obscured AGN from optical spectroscopic surveys. Methods. A sample of 94 narrow-line AGN

  8. An Experience of Statistical Method Application in Forest Survey at Angara River Region in 1932

    Directory of Open Access Journals (Sweden)

    L. N. Vashchuk

    2014-10-01

    Full Text Available Report of the Angara forest economic expedition of forest economic survey in 1932 on the left bank of the Angara River has been found. The survey covered a part of Krasnoyarsk Territory and Irkutsk region, a total area of 18641.8 thousand ha. The report describes technology of forest inventory and achievements that have not previously been published. The survey was conducted by statistical method, which consisted of a sample by a continuous forest inventory enumeration of trees on sample plots (SP, arranged in an array on a particular system, followed by mathematical-statistical recalculation of the sample results to the entire survey. To do this, strip finders (sights were cut in the latitudinal direction at a distance from one another at 16 km. On the hacked sights, by every 2 km, 0.1 ha (10 × 100 m SP were established. In total 32 forest inventory sights were hacked, with total length of 9931 km, which incorporated 4817 SP. The accuracy of forest resources’ inventory characteristics determining also was investigated using smaller sample plots. For this purpose, each of the SP were cut to smaller area of 0.01 ha (10 × 10 m, where independent continuous enumeration of trees was conducted, andsample trees were cut, measured and bucked to the assortments, to explore the tree stand assortment structure. At each «sample cutting area» all the trees were felled out from 44 cm and above DBH. At half of the sample plot with 5 × 10 m size, located in the eastern end, all the trees were felled out and measured from 24 cm and above DBH. Every four «sample cutting area» in the fifth, all the trees with 12 cm and above DBH were cut down and measured. According to the results of the work, a detailed description of forest resources in the whole Angara river basin, and across 17 forest exploitation areas was completed.

  9. Photometric calibration of the COMBO-17 survey with the Softassign Procrustes Matching method

    Science.gov (United States)

    Sheikhbahaee, Z.; Nakajima, R.; Erben, T.; Schneider, P.; Hildebrandt, H.; Becker, A. C.

    2017-11-01

    Accurate photometric calibration of optical data is crucial for photometric redshift estimation. We present the Softassign Procrustes Matching (SPM) method to improve the colour calibration upon the commonly used Stellar Locus Regression (SLR) method for the COMBO-17 survey. Our colour calibration approach can be categorised as a point-set matching method, which is frequently used in medical imaging and pattern recognition. We attain a photometric redshift precision Δz/(1 + zs) of better than 2 per cent. Our method is based on aligning the stellar locus of the uncalibrated stars to that of a spectroscopic sample of the Sloan Digital Sky Survey standard stars. We achieve our goal by finding a correspondence matrix between the two point-sets and applying the matrix to estimate the appropriate translations in multidimensional colour space. The SPM method is able to find the translation between two point-sets, despite the existence of noise and incompleteness of the common structures in the sets, as long as there is a distinct structure in at least one of the colour-colour pairs. We demonstrate the precision of our colour calibration method with a mock catalogue. The SPM colour calibration code is publicly available at https://neuronphysics@bitbucket.org/neuronphysics/spm.git.

  10. Sample normalization methods in quantitative metabolomics.

    Science.gov (United States)

    Wu, Yiman; Li, Liang

    2016-01-22

    To reveal metabolomic changes caused by a biological event in quantitative metabolomics, it is critical to use an analytical tool that can perform accurate and precise quantification to examine the true concentration differences of individual metabolites found in different samples. A number of steps are involved in metabolomic analysis including pre-analytical work (e.g., sample collection and storage), analytical work (e.g., sample analysis) and data analysis (e.g., feature extraction and quantification). Each one of them can influence the quantitative results significantly and thus should be performed with great care. Among them, the total sample amount or concentration of metabolites can be significantly different from one sample to another. Thus, it is critical to reduce or eliminate the effect of total sample amount variation on quantification of individual metabolites. In this review, we describe the importance of sample normalization in the analytical workflow with a focus on mass spectrometry (MS)-based platforms, discuss a number of methods recently reported in the literature and comment on their applicability in real world metabolomics applications. Sample normalization has been sometimes ignored in metabolomics, partially due to the lack of a convenient means of performing sample normalization. We show that several methods are now available and sample normalization should be performed in quantitative metabolomics where the analyzed samples have significant variations in total sample amounts. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Dark Energy Survey Year 1 results: cross-correlation redshifts - methods and systematics characterization

    Science.gov (United States)

    Gatti, M.; Vielzeuf, P.; Davis, C.; Cawthon, R.; Rau, M. M.; DeRose, J.; De Vicente, J.; Alarcon, A.; Rozo, E.; Gaztanaga, E.; Hoyle, B.; Miquel, R.; Bernstein, G. M.; Bonnett, C.; Carnero Rosell, A.; Castander, F. J.; Chang, C.; da Costa, L. N.; Gruen, D.; Gschwend, J.; Hartley, W. G.; Lin, H.; MacCrann, N.; Maia, M. A. G.; Ogando, R. L. C.; Roodman, A.; Sevilla-Noarbe, I.; Troxel, M. A.; Wechsler, R. H.; Asorey, J.; Davis, T. M.; Glazebrook, K.; Hinton, S. R.; Lewis, G.; Lidman, C.; Macaulay, E.; Möller, A.; O'Neill, C. R.; Sommer, N. E.; Uddin, S. A.; Yuan, F.; Zhang, B.; Abbott, T. M. C.; Allam, S.; Annis, J.; Bechtol, K.; Brooks, D.; Burke, D. L.; Carollo, D.; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; DePoy, D. L.; Desai, S.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Fosalba, P.; Frieman, J.; García-Bellido, J.; Gerdes, D. W.; Goldstein, D. A.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; Hoormann, J. K.; Jain, B.; James, D. J.; Jarvis, M.; Jeltema, T.; Johnson, M. W. G.; Johnson, M. D.; Krause, E.; Kuehn, K.; Kuhlmann, S.; Kuropatkin, N.; Li, T. S.; Lima, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Nichol, R. C.; Nord, B.; Plazas, A. A.; Reil, K.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sheldon, E.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Tucker, B. E.; Tucker, D. L.; Vikram, V.; Walker, A. R.; Weller, J.; Wester, W.; Wolf, R. C.

    2018-06-01

    We use numerical simulations to characterize the performance of a clustering-based method to calibrate photometric redshift biases. In particular, we cross-correlate the weak lensing source galaxies from the Dark Energy Survey Year 1 sample with redMaGiC galaxies (luminous red galaxies with secure photometric redshifts) to estimate the redshift distribution of the former sample. The recovered redshift distributions are used to calibrate the photometric redshift bias of standard photo-z methods applied to the same source galaxy sample. We apply the method to two photo-z codes run in our simulated data: Bayesian Photometric Redshift and Directional Neighbourhood Fitting. We characterize the systematic uncertainties of our calibration procedure, and find that these systematic uncertainties dominate our error budget. The dominant systematics are due to our assumption of unevolving bias and clustering across each redshift bin, and to differences between the shapes of the redshift distributions derived by clustering versus photo-zs. The systematic uncertainty in the mean redshift bias of the source galaxy sample is Δz ≲ 0.02, though the precise value depends on the redshift bin under consideration. We discuss possible ways to mitigate the impact of our dominant systematics in future analyses.

  12. Design and methodology of a mixed methods follow-up study to the 2014 Ghana Demographic and Health Survey.

    Science.gov (United States)

    Staveteig, Sarah; Aryeetey, Richmond; Anie-Ansah, Michael; Ahiadeke, Clement; Ortiz, Ladys

    2017-01-01

    The intended meaning behind responses to standard questions posed in large-scale health surveys are not always well understood. Systematic follow-up studies, particularly those which pose a few repeated questions followed by open-ended discussions, are well positioned to gauge stability and consistency of data and to shed light on the intended meaning behind survey responses. Such follow-up studies require extensive coordination and face challenges in protecting respondent confidentiality during the process of recontacting and reinterviewing participants. We describe practical field strategies for undertaking a mixed methods follow-up study during a large-scale health survey. The study was designed as a mixed methods follow-up study embedded within the 2014 Ghana Demographic and Health Survey (GDHS). The study was implemented in 13 clusters. Android tablets were used to import reference data from the parent survey and to administer the questionnaire, which asked a mixture of closed- and open-ended questions on reproductive intentions, decision-making, and family planning. Despite a number of obstacles related to recontacting respondents and concern about respondent fatigue, over 92 percent of the selected sub-sample were successfully recontacted and reinterviewed; all consented to audio recording. A confidential linkage between GDHS data, follow-up tablet data, and audio transcripts was successfully created for the purpose of analysis. We summarize the challenges in follow-up study design, including ethical considerations, sample size, auditing, filtering, successful use of tablets, and share lessons learned for future such follow-up surveys.

  13. Sampling and Analysis Plan for Supplemental Environmental Project: Aquatic Life Surveys

    Energy Technology Data Exchange (ETDEWEB)

    Berryhill, Jesse Tobias [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gaukler, Shannon Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-26

    As part of a settlement agreement for nuclear waste incidents in 2014, several supplemental environment projects (SEPs) were initiated at Los Alamos National Laboratory (LANL or the Laboratory) between the U.S. Department of Energy and the state of New Mexico. One SEP from this agreement consists of performing aquatic life surveys and will be used to assess the applicability of using generic ambient water-quality criteria (AWQC) for aquatic life. AWQC are generic criteria developed by the U.S. Environmental Protection Agency (EPA) to cover a broad range of aquatic species and are not unique to a specific region or state. AWQC are established by a composition of toxicity data, called species sensitivity distributions (SSDs), and are determined by LC50 (lethal concentration of 50% of the organisms studied) acute toxicity experiments for chemicals of interest. It is of interest to determine whether aquatic species inhabiting waters on the Pajarito Plateau are adequately protected using the current generic AWQC. The focus of this study will determine which aquatic species are present in ephemeral, intermittent, and perennial waters within LANL boundaries and from reference waters adjacent to LANL. If the species identified from these waters do not generally represent species used in the SSDs, then SSDs may need to be modified and AWQC may need to be updated. This sampling and analysis plan details the sampling methodology, surveillance locations, temporal scheduling, and analytical approaches that will be used to complete aquatic life surveys. A significant portion of this sampling and analysis plan was formalized by referring to Appendix E: SEP Aquatic Life Surveys DQO (Data Quality Objectives).

  14. THE ALFALFA H α SURVEY. I. PROJECT DESCRIPTION AND THE LOCAL STAR FORMATION RATE DENSITY FROM THE FALL SAMPLE

    International Nuclear Information System (INIS)

    Sistine, Angela Van; Salzer, John J.; Janowiecki, Steven; Sugden, Arthur; Giovanelli, Riccardo; Haynes, Martha P.; Jaskot, Anne E.; Wilcots, Eric M.

    2016-01-01

    The ALFALFA H α survey utilizes a large sample of H i-selected galaxies from the ALFALFA survey to study star formation (SF) in the local universe. ALFALFA H α contains 1555 galaxies with distances between ∼20 and ∼100 Mpc. We have obtained continuum-subtracted narrowband H α images and broadband R images for each galaxy, creating one of the largest homogeneous sets of H α images ever assembled. Our procedures were designed to minimize the uncertainties related to the calculation of the local SF rate density (SFRD). The galaxy sample we constructed is as close to volume-limited as possible, is a robust statistical sample, and spans a wide range of galaxy environments. In this paper, we discuss the properties of our Fall sample of 565 galaxies, our procedure for deriving individual galaxy SF rates, and our method for calculating the local SFRD. We present a preliminary value of log(SFRD[ M ⊙ yr −1 Mpc −3 ]) = −1.747 ± 0.018 (random) ±0.05 (systematic) based on the 565 galaxies in our Fall sub-sample. Compared to the weighted average of SFRD values around z ≈ 2, our local value indicates a drop in the global SFRD of a factor of 10.2 over that lookback time.

  15. Radioactive air sampling methods

    CERN Document Server

    Maiello, Mark L

    2010-01-01

    Although the field of radioactive air sampling has matured and evolved over decades, it has lacked a single resource that assimilates technical and background information on its many facets. Edited by experts and with contributions from top practitioners and researchers, Radioactive Air Sampling Methods provides authoritative guidance on measuring airborne radioactivity from industrial, research, and nuclear power operations, as well as naturally occuring radioactivity in the environment. Designed for industrial hygienists, air quality experts, and heath physicists, the book delves into the applied research advancing and transforming practice with improvements to measurement equipment, human dose modeling of inhaled radioactivity, and radiation safety regulations. To present a wide picture of the field, it covers the international and national standards that guide the quality of air sampling measurements and equipment. It discusses emergency response issues, including radioactive fallout and the assets used ...

  16. Methods for collecting algal samples as part of the National Water-Quality Assessment Program

    Science.gov (United States)

    Porter, Stephen D.; Cuffney, Thomas F.; Gurtz, Martin E.; Meador, Michael R.

    1993-01-01

    Benthic algae (periphyton) and phytoplankton communities are characterized in the U.S. Geological Survey's National Water-Quality Assessment Program as part of an integrated physical, chemical, and biological assessment of the Nation's water quality. This multidisciplinary approach provides multiple lines of evidence for evaluating water-quality status and trends, and for refining an understanding of the factors that affect water-quality conditions locally, regionally, and nationally. Water quality can be characterized by evaluating the results of qualitative and quantitative measurements of the algal community. Qualitative periphyton samples are collected to develop of list of taxa present in the sampling reach. Quantitative periphyton samples are collected to measure algal community structure within selected habitats. These samples of benthic algal communities are collected from natural substrates, using the sampling methods that are most appropriate for the habitat conditions. Phytoplankton samples may be collected in large nonwadeable streams and rivers to meet specific program objectives. Estimates of algal biomass (chlorophyll content and ash-free dry mass) also are optional measures that may be useful for interpreting water-quality conditions. A nationally consistent approach provides guidance on site, reach, and habitat selection, as well as information on methods and equipment for qualitative and quantitative sampling. Appropriate quality-assurance and quality-control guidelines are used to maximize the ability to analyze data locally, regionally, and nationally.

  17. Fluidics platform and method for sample preparation

    Science.gov (United States)

    Benner, Henry W.; Dzenitis, John M.

    2016-06-21

    Provided herein are fluidics platforms and related methods for performing integrated sample collection and solid-phase extraction of a target component of the sample all in one tube. The fluidics platform comprises a pump, particles for solid-phase extraction and a particle-holding means. The method comprises contacting the sample with one or more reagents in a pump, coupling a particle-holding means to the pump and expelling the waste out of the pump while the particle-holding means retains the particles inside the pump. The fluidics platform and methods herein described allow solid-phase extraction without pipetting and centrifugation.

  18. Methods of removing uranium from drinking water. 1. A literature survey. 2. Present municipal water treatment and potential removal methods

    International Nuclear Information System (INIS)

    Drury, J.S.; Michelson, D.; Ensminger, J.T.; Lee, S.Y.; White, S.K.

    1982-12-01

    Literature was searched for methods of removing uranium from drinking water. U.S. manufacturers and users of water-treatment equipment and products were also contacted regarding methods of removing uranium from potable water. Based on the results of these surveys, it was recommended that untreated, partially treated, and finished water samples from municipal water-treatment facilities be analyzed to determine the extent of removal of uranium by presently used procedures, and that additional laboratory studies be performed to determine what changes are needed to maximize the effectiveness of treatments that are already in use in existing water-treatment plants

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

    Science.gov (United States)

    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…

  20. Statistical searches for microlensing events in large, non-uniformly sampled time-domain surveys: A test using palomar transient factory data

    Energy Technology Data Exchange (ETDEWEB)

    Price-Whelan, Adrian M.; Agüeros, Marcel A. [Department of Astronomy, Columbia University, 550 W 120th Street, New York, NY 10027 (United States); Fournier, Amanda P. [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106 (United States); Street, Rachel [Las Cumbres Observatory Global Telescope Network, Inc., 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Ofek, Eran O. [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Covey, Kevin R. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Levitan, David; Sesar, Branimir [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Laher, Russ R.; Surace, Jason, E-mail: adrn@astro.columbia.edu [Spitzer Science Center, California Institute of Technology, Mail Stop 314-6, Pasadena, CA 91125 (United States)

    2014-01-20

    Many photometric time-domain surveys are driven by specific goals, such as searches for supernovae or transiting exoplanets, which set the cadence with which fields are re-imaged. In the case of the Palomar Transient Factory (PTF), several sub-surveys are conducted in parallel, leading to non-uniform sampling over its ∼20,000 deg{sup 2} footprint. While the median 7.26 deg{sup 2} PTF field has been imaged ∼40 times in the R band, ∼2300 deg{sup 2} have been observed >100 times. We use PTF data to study the trade off between searching for microlensing events in a survey whose footprint is much larger than that of typical microlensing searches, but with far-from-optimal time sampling. To examine the probability that microlensing events can be recovered in these data, we test statistics used on uniformly sampled data to identify variables and transients. We find that the von Neumann ratio performs best for identifying simulated microlensing events in our data. We develop a selection method using this statistic and apply it to data from fields with >10 R-band observations, 1.1 × 10{sup 9} light curves, uncovering three candidate microlensing events. We lack simultaneous, multi-color photometry to confirm these as microlensing events. However, their number is consistent with predictions for the event rate in the PTF footprint over the survey's three years of operations, as estimated from near-field microlensing models. This work can help constrain all-sky event rate predictions and tests microlensing signal recovery in large data sets, which will be useful to future time-domain surveys, such as that planned with the Large Synoptic Survey Telescope.

  1. THE BOSS EMISSION-LINE LENS SURVEY (BELLS). I. A LARGE SPECTROSCOPICALLY SELECTED SAMPLE OF LENS GALAXIES AT REDSHIFT {approx}0.5

    Energy Technology Data Exchange (ETDEWEB)

    Brownstein, Joel R.; Bolton, Adam S.; Pandey, Parul [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Schlegel, David J. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Eisenstein, Daniel J. [Harvard College Observatory, 60 Garden Street, MS 20, Cambridge, MA 02138 (United States); Kochanek, Christopher S. [Department of Astronomy and Center for Cosmology and Astroparticle Physics, Ohio State University, Columbus, OH 43210 (United States); Connolly, Natalia [Department of Physics, Hamilton College, Clinton, NY 13323 (United States); Maraston, Claudia [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth PO1 3FX (United Kingdom); Seitz, Stella [University Observatory Munich, Scheinstrasse 1, 81679 Muenchen (Germany); Wake, David A. [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Wood-Vasey, W. Michael [Pittsburgh Center for Particle Physics, Astrophysics, and Cosmology (PITT-PACC), Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Brinkmann, Jon [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics and Institute for Gravitation and the Cosmos, Pennsylvania State University, University Park, PA 16802 (United States); Weaver, Benjamin A. [Center for Cosmology and Particle Physics, New York University, New York, NY 10003 (United States)

    2012-01-01

    We present a catalog of 25 definite and 11 probable strong galaxy-galaxy gravitational lens systems with lens redshifts 0.4 {approx}< z {approx}< 0.7, discovered spectroscopically by the presence of higher-redshift emission lines within the Baryon Oscillation Spectroscopic Survey (BOSS) of luminous galaxies, and confirmed with high-resolution Hubble Space Telescope (HST) images of 44 candidates. Our survey extends the methodology of the Sloan Lens Advanced Camera for Surveys survey (SLACS) to higher redshift. We describe the details of the BOSS spectroscopic candidate detections, our HST ACS image processing and analysis methods, and our strong gravitational lens modeling procedure. We report BOSS spectroscopic parameters and ACS photometric parameters for all candidates, and mass-distribution parameters for the best-fit singular isothermal ellipsoid models of definite lenses. Our sample to date was selected using only the first six months of BOSS survey-quality spectroscopic data. The full five-year BOSS database should produce a sample of several hundred strong galaxy-galaxy lenses and in combination with SLACS lenses at lower redshift, strongly constrain the redshift evolution of the structure of elliptical, bulge-dominated galaxies as a function of luminosity, stellar mass, and rest-frame color, thereby providing a powerful test for competing theories of galaxy formation and evolution.

  2. Prenotification, Incentives, and Survey Modality: An Experimental Test of Methods to Increase Survey Response Rates of School Principals

    Science.gov (United States)

    Jacob, Robin Tepper; Jacob, Brian

    2012-01-01

    Teacher and principal surveys are among the most common data collection techniques employed in education research. Yet there is remarkably little research on survey methods in education, or about the most cost-effective way to raise response rates among teachers and principals. In an effort to explore various methods for increasing survey response…

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

    Science.gov (United States)

    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. Improved sampling for airborne surveys to estimate wildlife population parameters in the African Savannah

    NARCIS (Netherlands)

    Khaemba, W.; Stein, A.

    2002-01-01

    Parameter estimates, obtained from airborne surveys of wildlife populations, often have large bias and large standard errors. Sampling error is one of the major causes of this imprecision and the occurrence of many animals in herds violates the common assumptions in traditional sampling designs like

  5. Hepatitis C bio-behavioural surveys in people who inject drugs-a systematic review of sensitivity to the theoretical assumptions of respondent driven sampling.

    Science.gov (United States)

    Buchanan, Ryan; Khakoo, Salim I; Coad, Jonathan; Grellier, Leonie; Parkes, Julie

    2017-07-11

    New, more effective and better-tolerated therapies for hepatitis C (HCV) have made the elimination of HCV a feasible objective. However, for this to be achieved, it is necessary to have a detailed understanding of HCV epidemiology in people who inject drugs (PWID). Respondent-driven sampling (RDS) can provide prevalence estimates in hidden populations such as PWID. The aims of this systematic review are to identify published studies that use RDS in PWID to measure the prevalence of HCV, and compare each study against the STROBE-RDS checklist to assess their sensitivity to the theoretical assumptions underlying RDS. Searches were undertaken in accordance with PRISMA systematic review guidelines. Included studies were English language publications in peer-reviewed journals, which reported the use of RDS to recruit PWID to an HCV bio-behavioural survey. Data was extracted under three headings: (1) survey overview, (2) survey outcomes, and (3) reporting against selected STROBE-RDS criteria. Thirty-one studies met the inclusion criteria. They varied in scale (range 1-15 survey sites) and the sample sizes achieved (range 81-1000 per survey site) but were consistent in describing the use of standard RDS methods including: seeds, coupons and recruitment incentives. Twenty-seven studies (87%) either calculated or reported the intention to calculate population prevalence estimates for HCV and two used RDS data to calculate the total population size of PWID. Detailed operational and analytical procedures and reporting against selected criteria from the STROBE-RDS checklist varied between studies. There were widespread indications that sampling did not meet the assumptions underlying RDS, which led to two studies being unable to report an estimated HCV population prevalence in at least one survey location. RDS can be used to estimate a population prevalence of HCV in PWID and estimate the PWID population size. Accordingly, as a single instrument, it is a useful tool for

  6. Adaptive geostatistical sampling enables efficient identification of malaria hotspots in repeated cross-sectional surveys in rural Malawi.

    Directory of Open Access Journals (Sweden)

    Alinune N Kabaghe

    Full Text Available In the context of malaria elimination, interventions will need to target high burden areas to further reduce transmission. Current tools to monitor and report disease burden lack the capacity to continuously detect fine-scale spatial and temporal variations of disease distribution exhibited by malaria. These tools use random sampling techniques that are inefficient for capturing underlying heterogeneity while health facility data in resource-limited settings are inaccurate. Continuous community surveys of malaria burden provide real-time results of local spatio-temporal variation. Adaptive geostatistical design (AGD improves prediction of outcome of interest compared to current random sampling techniques. We present findings of continuous malaria prevalence surveys using an adaptive sampling design.We conducted repeated cross sectional surveys guided by an adaptive sampling design to monitor the prevalence of malaria parasitaemia and anaemia in children below five years old in the communities living around Majete Wildlife Reserve in Chikwawa district, Southern Malawi. AGD sampling uses previously collected data to sample new locations of high prediction variance or, where prediction exceeds a set threshold. We fitted a geostatistical model to predict malaria prevalence in the area.We conducted five rounds of sampling, and tested 876 children aged 6-59 months from 1377 households over a 12-month period. Malaria prevalence prediction maps showed spatial heterogeneity and presence of hotspots-where predicted malaria prevalence was above 30%; predictors of malaria included age, socio-economic status and ownership of insecticide-treated mosquito nets.Continuous malaria prevalence surveys using adaptive sampling increased malaria prevalence prediction accuracy. Results from the surveys were readily available after data collection. The tool can assist local managers to target malaria control interventions in areas with the greatest health impact and is

  7. Biological variables for the site survey of surface ecosystems - existing data and survey methods

    International Nuclear Information System (INIS)

    Kylaekorpi, Lasse; Berggren, Jens; Larsson, Mats; Liberg, Maria; Rydgren, Bernt

    2000-06-01

    In the process of selecting a safe and environmentally acceptable location for the deep level repository of nuclear waste, site surveys will be carried out. These site surveys will also include studies of the biota at the site, in order to assure that the chosen site will not conflict with important ecological interests, and to establish a thorough baseline for future impact assessments and monitoring programmes. As a preparation to the site survey programme, a review of the variables that need to be surveyed is conducted. This report contains the review for some of those variables. For each variable, existing data sources and their characteristics are listed. For those variables for which existing data sources are inadequate, suggestions are made for appropriate methods that will enable the establishment of an acceptable baseline. In this report the following variables are reviewed: Fishery, Landscape, Vegetation types, Key biotopes, Species (flora and fauna), Red-listed species (flora and fauna), Biomass (flora and fauna), Water level, water retention time (incl. water body and flow), Nutrients/toxins, Oxygen concentration, Layering, stratification, Light conditions/transparency, Temperature, Sediment transport, (Marine environments are excluded from this review). For a major part of the variables, the existing data coverage is most likely insufficient. Both the temporal and/or the geographical resolution is often limited, which means that complementary surveys must be performed during (or before) the site surveys. It is, however, in general difficult to make exact judgements on the extent of existing data, and also to give suggestions for relevant methods to use in the site surveys. This can be finally decided only when the locations for the sites are decided upon. The relevance of the different variables also depends on the environmental characteristics of the sites. Therefore, we suggest that when the survey sites are selected, an additional review is

  8. Biological variables for the site survey of surface ecosystems - existing data and survey methods

    Energy Technology Data Exchange (ETDEWEB)

    Kylaekorpi, Lasse; Berggren, Jens; Larsson, Mats; Liberg, Maria; Rydgren, Bernt [SwedPower AB, Stockholm (Sweden)

    2000-06-01

    In the process of selecting a safe and environmentally acceptable location for the deep level repository of nuclear waste, site surveys will be carried out. These site surveys will also include studies of the biota at the site, in order to assure that the chosen site will not conflict with important ecological interests, and to establish a thorough baseline for future impact assessments and monitoring programmes. As a preparation to the site survey programme, a review of the variables that need to be surveyed is conducted. This report contains the review for some of those variables. For each variable, existing data sources and their characteristics are listed. For those variables for which existing data sources are inadequate, suggestions are made for appropriate methods that will enable the establishment of an acceptable baseline. In this report the following variables are reviewed: Fishery, Landscape, Vegetation types, Key biotopes, Species (flora and fauna), Red-listed species (flora and fauna), Biomass (flora and fauna), Water level, water retention time (incl. water body and flow), Nutrients/toxins, Oxygen concentration, Layering, stratification, Light conditions/transparency, Temperature, Sediment transport, (Marine environments are excluded from this review). For a major part of the variables, the existing data coverage is most likely insufficient. Both the temporal and/or the geographical resolution is often limited, which means that complementary surveys must be performed during (or before) the site surveys. It is, however, in general difficult to make exact judgements on the extent of existing data, and also to give suggestions for relevant methods to use in the site surveys. This can be finally decided only when the locations for the sites are decided upon. The relevance of the different variables also depends on the environmental characteristics of the sites. Therefore, we suggest that when the survey sites are selected, an additional review is

  9. Methodical recommendations for power unit comprehensive engineering and radiation survey

    International Nuclear Information System (INIS)

    Nosovskij, A.V.

    2000-01-01

    The article describes power unit radiation survey methods developed and applied during conduction of Ch NPP unit I Comprehensive Engineering Radiation Survey. Special requirements for units under decommissioning, main survey principals, criteria for definition of volume and the order of survey for various systems of a NPP Unit are included

  10. On-capillary sample cleanup method for the electrophoretic determination of carbohydrates in juice samples.

    Science.gov (United States)

    Morales-Cid, Gabriel; Simonet, Bartolomé M; Cárdenas, Soledad; Valcárcel, Miguel

    2007-05-01

    On many occasions, sample treatment is a critical step in electrophoretic analysis. As an alternative to batch procedures, in this work, a new strategy is presented with a view to develop an on-capillary sample cleanup method. This strategy is based on the partial filling of the capillary with carboxylated single-walled carbon nanotube (c-SWNT). The nanoparticles retain interferences from the matrix allowing the determination and quantification of carbohydrates (viz glucose, maltose and fructose). The precision of the method for the analysis of real samples ranged from 5.3 to 6.4%. The proposed method was compared with a method based on a batch filtration of the juice sample through diatomaceous earth and further electrophoretic determination. This method was also validated in this work. The RSD for this other method ranged from 5.1 to 6%. The results obtained by both methods were statistically comparable demonstrating the accuracy of the proposed methods and their effectiveness. Electrophoretic separation of carbohydrates was achieved using 200 mM borate solution as a buffer at pH 9.5 and applying 15 kV. During separation, the capillary temperature was kept constant at 40 degrees C. For the on-capillary cleanup method, a solution containing 50 mg/L of c-SWNTs prepared in 300 mM borate solution at pH 9.5 was introduced for 60 s into the capillary just before sample introduction. For the electrophoretic analysis of samples cleaned in batch with diatomaceous earth, it is also recommended to introduce into the capillary, just before the sample, a 300 mM borate solution as it enhances the sensitivity and electrophoretic resolution.

  11. A new survey method of tsunami inundation area using chemical analysis of soil. Application to the field survey on the 2010 Chilean tsunami at Chile

    International Nuclear Information System (INIS)

    Yoshii, Takumi; Matsuyama, Masafumi; Koshimura, Shunichi; Mas, Erick; Matsuoka, Masashi; Jimenez, Cesar

    2011-01-01

    The severe earthquake of Mw 8.8 occurred on 27 Feb. 2010 at the center of Chile. The tsunami generated by the earthquake attacked the coast of Chile and it propagated to the Pacific Ocean coastline. The field survey on the disaster damages due to the tsunami was conducted near Talcahuano in Chile to prepare for the great tsunamis accompanied by the earthquakes predicted to occur near Japan within several decades. The aims of this field survey were to survey disaster damages especially relevant to electric equipments and to develop the survey method based on a chemical analysis of the inundated soil which supplies objective data with high accuracy compared to the conventional methods. In the survey area, the average of inundation heights was 6 m, however it locally reached up to 25 m. The maximum sea-level height of the series of the tsunamis was recorded in the third or fourth wave (roughly 3 hours after the earthquake occurrence). The first floors of houses were severely destroyed and some ships were carried and left on land by the tsunamis. Furthermore, the large amount of sediment was deposited in towns. Removing the drifted ships and tsunami deposit is important consideration for quick recovery from a disaster due to a tsunami. The soil samples were obtained from both the inundated and the not-inundated position. The stirred solution was made by the soil and ultrapure water, then, the content of water-soluble ions, electric conductivity (EC), and pH were measured. The soil obtained in the tsunami inundated area contains much water-soluble ions (Na + , Mg 2+ , Cl - , Br - , SO 4 2- ) compared to the samples obtained in the not-inundated area. The discriminant analysis of the tsunami inundation was conducted using the amount of ions in the soil. High discriminant accuracy (over 90%) was obtained with Na + , Mg 2+ , Cl - , Br - , SO 4 2- and EC. Br - , Cl - , Na + are believed to be suitable for the discriminant analysis about tsunamis considering the contaminant

  12. Present status of NMCC and sample preparation method for bio-samples

    International Nuclear Information System (INIS)

    Futatsugawa, S.; Hatakeyama, S.; Saitou, S.; Sera, K.

    1993-01-01

    In NMCC(Nishina Memorial Cyclotron Center) we are doing researches on PET of nuclear medicine (Positron Emission Computed Tomography) and PIXE analysis (Particle Induced X-ray Emission) using a small cyclotron of compactly designed. The NMCC facilities have been opened to researchers of other institutions since April 1993. The present status of NMCC is described. Bio-samples (medical samples, plants, animals and environmental samples) have mainly been analyzed by PIXE in NMCC. Small amounts of bio-samples for PIXE are decomposed quickly and easily in a sealed PTFE (polytetrafluoroethylene) vessel with a microwave oven. This sample preparation method of bio-samples also is described. (author)

  13. Assessing the Relationship between Family Mealtime Communication and Adolescent Emotional Well-Being Using the Experience Sampling Method

    Science.gov (United States)

    Offer, Shira

    2013-01-01

    While most prior research has focused on the frequency of family meals the issue of which elements of family mealtime are most salient for adolescents' well-being has remained overlooked. The current study used the experience sampling method, a unique form of time diary, and survey data drawn from the 500 Family Study (N = 237 adolescents with…

  14. Direct sampling methods for inverse elastic scattering problems

    Science.gov (United States)

    Ji, Xia; Liu, Xiaodong; Xi, Yingxia

    2018-03-01

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

  15. Web-based Survey Data Collection With Peer Support and Advocacy Organizations: Implications of Participatory Methods.

    Science.gov (United States)

    Ostrow, Laysha; Penney, Darby; Stuart, Elizabeth; Leaf, Phillip J

    2017-01-01

    The 2012 National Survey of Peer-Run Organizations is one of the first to survey a nationally representative sample of mental health peer-run organizations, nonprofit venues for support and advocacy which are defined by people with psychiatric histories being in positions of authority and control. This paper describes data collection methods and demonstrates how participatory strategies to involve people with psychiatric histories intersected with Internet research to achieve study aims. People with psychiatric histories were involved in designing and implementing a web-based survey to collect data on peer-run organizations' operations and views on national policy. Participatory approaches were used throughout design, data collection analysis, and dissemination. The extensive involvement of people with psychiatric histories in project design and implementation were important strategies that contributed to this study's success.

  16. Penggunaan Metode Respondent Driven Sampling (Rds dalam Survey Pemasaran Beras di Provinsi Kepulauan Riau

    Directory of Open Access Journals (Sweden)

    Herena Pudjihastuti

    2014-06-01

    Full Text Available As a Free Trade Zone (FTZ, the province of Riau Islands has a different pattern of strategic commodity (such as rice marketing comparing to other regions in Indonesia. To anticipate and control the negative effects of the implementation of FTZ policy, It is necessary to study about rice marketing trade system in the Riau Islands region. The study was conducted to identify patterns of supply and marketing of food (rice and analyze the marketing margin and marketing efficiency as well as the factors that influence it. The study was conducted through desk study and field surveys. Secondary data was collected from various sources and primary data collected through interviews with selected respondents using Respondent Driven Sampling method (RDS. The study shows that the structure of the rice market in Riau Islands can be categorized as monopolistic. Most of the rice supply comes from outside the region and import, the supply chain is quite simple, the price is relatively stable and relatively efficient marketing and resilience of rice reserves are relatively high for merchants. Nevertheless, the Riau islands will be very susceptible to interference distribution. Required efforts of the provincial government of Riau Islands to provide sufficient rice reserves. This paper gives an example of the use of the RDS method in marketing surveys.

  17. Optimal power flow: a bibliographic survey I. Formulations and deterministic methods

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Stephen [Colorado School of Mines, Department of Electrical Engineering and Computer Science, Golden, CO (United States); Steponavice, Ingrida [University of Jyvaskyla, Department of Mathematical Information Technology, Agora (Finland); Rebennack, Steffen [Colorado School of Mines, Division of Economics and Business, Golden, CO (United States)

    2012-09-15

    Over the past half-century, optimal power flow (OPF) has become one of the most important and widely studied nonlinear optimization problems. In general, OPF seeks to optimize the operation of electric power generation, transmission, and distribution networks subject to system constraints and control limits. Within this framework, however, there is an extremely wide variety of OPF formulations and solution methods. Moreover, the nature of OPF continues to evolve due to modern electricity markets and renewable resource integration. In this two-part survey, we survey both the classical and recent OPF literature in order to provide a sound context for the state of the art in OPF formulation and solution methods. The survey contributes a comprehensive discussion of specific optimization techniques that have been applied to OPF, with an emphasis on the advantages, disadvantages, and computational characteristics of each. Part I of the survey (this article) provides an introduction and surveys the deterministic optimization methods that have been applied to OPF. Part II of the survey examines the recent trend towards stochastic, or non-deterministic, search techniques and hybrid methods for OPF. (orig.)

  18. CT dose survey in adults: what sample size for what precision?

    International Nuclear Information System (INIS)

    Taylor, Stephen; Muylem, Alain van; Howarth, Nigel; Gevenois, Pierre Alain; Tack, Denis

    2017-01-01

    To determine variability of volume computed tomographic dose index (CTDIvol) and dose-length product (DLP) data, and propose a minimum sample size to achieve an expected precision. CTDIvol and DLP values of 19,875 consecutive CT acquisitions of abdomen (7268), thorax (3805), lumbar spine (3161), cervical spine (1515) and head (4106) were collected in two centers. Their variabilities were investigated according to sample size (10 to 1000 acquisitions) and patient body weight categories (no weight selection, 67-73 kg and 60-80 kg). The 95 % confidence interval in percentage of their median (CI95/med) value was calculated for increasing sample sizes. We deduced the sample size that set a 95 % CI lower than 10 % of the median (CI95/med ≤ 10 %). Sample size ensuring CI95/med ≤ 10 %, ranged from 15 to 900 depending on the body region and the dose descriptor considered. In sample sizes recommended by regulatory authorities (i.e., from 10-20 patients), mean CTDIvol and DLP of one sample ranged from 0.50 to 2.00 times its actual value extracted from 2000 samples. The sampling error in CTDIvol and DLP means is high in dose surveys based on small samples of patients. Sample size should be increased at least tenfold to decrease this variability. (orig.)

  19. CT dose survey in adults: what sample size for what precision?

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Stephen [Hopital Ambroise Pare, Department of Radiology, Mons (Belgium); Muylem, Alain van [Hopital Erasme, Department of Pneumology, Brussels (Belgium); Howarth, Nigel [Clinique des Grangettes, Department of Radiology, Chene-Bougeries (Switzerland); Gevenois, Pierre Alain [Hopital Erasme, Department of Radiology, Brussels (Belgium); Tack, Denis [EpiCURA, Clinique Louis Caty, Department of Radiology, Baudour (Belgium)

    2017-01-15

    To determine variability of volume computed tomographic dose index (CTDIvol) and dose-length product (DLP) data, and propose a minimum sample size to achieve an expected precision. CTDIvol and DLP values of 19,875 consecutive CT acquisitions of abdomen (7268), thorax (3805), lumbar spine (3161), cervical spine (1515) and head (4106) were collected in two centers. Their variabilities were investigated according to sample size (10 to 1000 acquisitions) and patient body weight categories (no weight selection, 67-73 kg and 60-80 kg). The 95 % confidence interval in percentage of their median (CI95/med) value was calculated for increasing sample sizes. We deduced the sample size that set a 95 % CI lower than 10 % of the median (CI95/med ≤ 10 %). Sample size ensuring CI95/med ≤ 10 %, ranged from 15 to 900 depending on the body region and the dose descriptor considered. In sample sizes recommended by regulatory authorities (i.e., from 10-20 patients), mean CTDIvol and DLP of one sample ranged from 0.50 to 2.00 times its actual value extracted from 2000 samples. The sampling error in CTDIvol and DLP means is high in dose surveys based on small samples of patients. Sample size should be increased at least tenfold to decrease this variability. (orig.)

  20. THE ALFALFA H α SURVEY. I. PROJECT DESCRIPTION AND THE LOCAL STAR FORMATION RATE DENSITY FROM THE FALL SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Sistine, Angela Van [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI 53211 (United States); Salzer, John J.; Janowiecki, Steven [Department of Astronomy, Indiana University, Bloomington, IN 47405 (United States); Sugden, Arthur [Department of Endocrinology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115 (United States); Giovanelli, Riccardo; Haynes, Martha P. [Center for Astrophysics and Planetary Science, Cornell University, Ithaca, NY 14853 (United States); Jaskot, Anne E. [Department of Astronomy, Smith College, Northampton, MA 01063 (United States); Wilcots, Eric M. [Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706 (United States)

    2016-06-10

    The ALFALFA H α survey utilizes a large sample of H i-selected galaxies from the ALFALFA survey to study star formation (SF) in the local universe. ALFALFA H α contains 1555 galaxies with distances between ∼20 and ∼100 Mpc. We have obtained continuum-subtracted narrowband H α images and broadband R images for each galaxy, creating one of the largest homogeneous sets of H α images ever assembled. Our procedures were designed to minimize the uncertainties related to the calculation of the local SF rate density (SFRD). The galaxy sample we constructed is as close to volume-limited as possible, is a robust statistical sample, and spans a wide range of galaxy environments. In this paper, we discuss the properties of our Fall sample of 565 galaxies, our procedure for deriving individual galaxy SF rates, and our method for calculating the local SFRD. We present a preliminary value of log(SFRD[ M {sub ⊙} yr{sup −1} Mpc{sup −3}]) = −1.747 ± 0.018 (random) ±0.05 (systematic) based on the 565 galaxies in our Fall sub-sample. Compared to the weighted average of SFRD values around z ≈ 2, our local value indicates a drop in the global SFRD of a factor of 10.2 over that lookback time.

  1. Underwater photography - A visual survey method

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, R.

    Content-Type text/plain; charset=UTF-8 173 Underwater photography - A visual survey method Rahul Sharma National Institute of Oceanography, Dona Paula, Goa-403004 rsharma@nio.org Introduction “Photography as a means of observing...-sea photographs were those made by Maurice Ewing and his co-workers during cruises on Atlantis in 1940-48. Their subject was the seafloor and their method of clicking was to trigger the camera mechanically when its mounting struck bottom. This is the only...

  2. Sampling Methods for Wallenius' and Fisher's Noncentral Hypergeometric Distributions

    DEFF Research Database (Denmark)

    Fog, Agner

    2008-01-01

    the mode, ratio-of-uniforms rejection method, and rejection by sampling in the tau domain. Methods for the multivariate distributions include: simulation of urn experiments, conditional method, Gibbs sampling, and Metropolis-Hastings sampling. These methods are useful for Monte Carlo simulation of models...... of biased sampling and models of evolution and for calculating moments and quantiles of the distributions.......Several methods for generating variates with univariate and multivariate Wallenius' and Fisher's noncentral hypergeometric distributions are developed. Methods for the univariate distributions include: simulation of urn experiments, inversion by binary search, inversion by chop-down search from...

  3. DOE methods for evaluating environmental and waste management samples

    International Nuclear Information System (INIS)

    Goheen, S.C.; McCulloch, M.; Thomas, B.L.; Riley, R.G.; Sklarew, D.S.; Mong, G.M.; Fadeff, S.K.

    1993-03-01

    DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) provides applicable methods in use by. the US Department of Energy (DOE) laboratories for sampling and analyzing constituents of waste and environmental samples. The development of DOE Methods is supported by the Laboratory Management Division (LMD) of the DOE. This document contains chapters and methods that are proposed for use in evaluating components of DOE environmental and waste management samples. DOE Methods is a resource intended to support sampling and analytical activities that will aid in defining the type and breadth of contamination and thus determine the extent of environmental restoration or waste management actions needed, as defined by the DOE, the US Environmental Protection Agency (EPA), or others

  4. DOE methods for evaluating environmental and waste management samples.

    Energy Technology Data Exchange (ETDEWEB)

    Goheen, S C; McCulloch, M; Thomas, B L; Riley, R G; Sklarew, D S; Mong, G M; Fadeff, S K [eds.; Pacific Northwest Lab., Richland, WA (United States)

    1994-04-01

    DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) provides applicable methods in use by. the US Department of Energy (DOE) laboratories for sampling and analyzing constituents of waste and environmental samples. The development of DOE Methods is supported by the Laboratory Management Division (LMD) of the DOE. This document contains chapters and methods that are proposed for use in evaluating components of DOE environmental and waste management samples. DOE Methods is a resource intended to support sampling and analytical activities that will aid in defining the type and breadth of contamination and thus determine the extent of environmental restoration or waste management actions needed, as defined by the DOE, the US Environmental Protection Agency (EPA), or others.

  5. Scientists' attitudes on science and values: Case studies and survey methods in philosophy of science.

    Science.gov (United States)

    Steel, Daniel; Gonnerman, Chad; O'Rourke, Michael

    2017-06-01

    This article examines the relevance of survey data of scientists' attitudes about science and values to case studies in philosophy of science. We describe two methodological challenges confronting such case studies: 1) small samples, and 2) potential for bias in selection, emphasis, and interpretation. Examples are given to illustrate that these challenges can arise for case studies in the science and values literature. We propose that these challenges can be mitigated through an approach in which case studies and survey methods are viewed as complementary, and use data from the Toolbox Dialogue Initiative to illustrate this claim. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Does the Underground Sidewall Station Survey Method Meet MHSA ...

    African Journals Online (AJOL)

    Grobler, Hendrik

    The underground survey network in a deep level platinum mine in ... The time duration for peg installation during the initial phase of learning the method was ..... changes to the survey “hardware” including prisms, stems and attachment points ...

  7. Evaluation of carbon monoxide in blood samples from the second health and nutrition survey. Progress report No. 1

    Energy Technology Data Exchange (ETDEWEB)

    Radford, E.P.

    1976-01-01

    This is a study of carbon monoxide (CO) in the blood of human subjects participating in the Second National Health and Nutrition Survey (HANES II), a detailed study of health indicators in sample populations of many communities throughout the U.S. The purpose of this aspect of the survey is to evaluate the levels of blood carboxyhemoglobin in normal individuals of all ages in typical U.S. communities, from whom accurate histories and clinical studies are available. This report gives results of the first of three years of analyses. A careful calibration of the analytical method has been completed, and more than 3000 blood samples have been analyzed. Although smoking histories are not yet available to permit evaluation of carboxyhemoglobin in non-smokers, in children under 12 years of age, blood COHb has been found to be consistently low, with less than 3% greater than 1.5% COHb. These preliminary results suggest that urban exposure to carbon monoxide among the general population is not now significant in the U.S., at least during the period of these early examinations.

  8. Failure Probability Calculation Method Using Kriging Metamodel-based Importance Sampling Method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seunggyu [Korea Aerospace Research Institue, Daejeon (Korea, Republic of); Kim, Jae Hoon [Chungnam Nat’l Univ., Daejeon (Korea, Republic of)

    2017-05-15

    The kernel density was determined based on sampling points obtained in a Markov chain simulation and was assumed to be an important sampling function. A Kriging metamodel was constructed in more detail in the vicinity of a limit state. The failure probability was calculated based on importance sampling, which was performed for the Kriging metamodel. A pre-existing method was modified to obtain more sampling points for a kernel density in the vicinity of a limit state. A stable numerical method was proposed to find a parameter of the kernel density. To assess the completeness of the Kriging metamodel, the possibility of changes in the calculated failure probability due to the uncertainty of the Kriging metamodel was calculated.

  9. Measuring the health of the Indian elderly: evidence from National Sample Survey data

    Directory of Open Access Journals (Sweden)

    Mahal Ajay

    2010-11-01

    Full Text Available Abstract Background Comparable health measures across different sets of populations are essential for describing the distribution of health outcomes and assessing the impact of interventions on these outcomes. Self-reported health (SRH is a commonly used indicator of health in household surveys and has been shown to be predictive of future mortality. However, the susceptibility of SRH to influence by individuals' expectations complicates its interpretation and undermines its usefulness. Methods This paper applies the empirical methodology of Lindeboom and van Doorslaer (2004 to investigate elderly health in India using data from the 52nd round of the National Sample Survey conducted in 1995-96 that includes both an SRH variable as well as a range of objective indicators of disability and ill health. The empirical testing was conducted on stratified homogeneous groups, based on four factors: gender, education, rural-urban residence, and region. Results We find that region generally has a significant impact on how women perceive their health. Reporting heterogeneity can arise not only from cut-point shifts, but also from differences in health effects by objective health measures. In contrast, we find little evidence of reporting heterogeneity due to differences in gender or educational status within regions. Rural-urban residence does matter in some cases. The findings are robust with different specifications of objective health indicators. Conclusions Our exercise supports the thesis that the region of residence is associated with different cut-points and reporting behavior on health surveys. We believe this is the first paper that applies the Lindeboom-van Doorslaer methodology to data on the elderly in a developing country, showing the feasibility of applying this methodology to data from many existing cross-sectional health surveys.

  10. 40 CFR Appendix I to Part 261 - Representative Sampling Methods

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Representative Sampling Methods I...—Representative Sampling Methods The methods and equipment used for sampling waste materials will vary with the form and consistency of the waste materials to be sampled. Samples collected using the sampling...

  11. Systematic sampling with errors in sample locations

    DEFF Research Database (Denmark)

    Ziegel, Johanna; Baddeley, Adrian; Dorph-Petersen, Karl-Anton

    2010-01-01

    analysis using point process methods. We then analyze three different models for the error process, calculate exact expressions for the variances, and derive asymptotic variances. Errors in the placement of sample points can lead to substantial inflation of the variance, dampening of zitterbewegung......Systematic sampling of points in continuous space is widely used in microscopy and spatial surveys. Classical theory provides asymptotic expressions for the variance of estimators based on systematic sampling as the grid spacing decreases. However, the classical theory assumes that the sample grid...... is exactly periodic; real physical sampling procedures may introduce errors in the placement of the sample points. This paper studies the effect of errors in sample positioning on the variance of estimators in the case of one-dimensional systematic sampling. First we sketch a general approach to variance...

  12. Using Social Media and Targeted Snowball Sampling to Survey a Hard-to-reach Population: A Case Study

    Directory of Open Access Journals (Sweden)

    Gary Dusek

    2015-08-01

    Full Text Available Response rates to the academic surveys used in quantitative research are decreasing and have been for several decades among both individuals and organizations. Given this trend, providing doctoral students an opportunity to complete their dissertations in a timely and cost effective manner may necessitate identifying more innovative and relevant ways to collect data while maintaining appropriate research standards and rigor. The case of a research study is presented which describes the data collection process used to survey a hard-to-reach population. It details the use of social media, in this case LinkedIn, to facilitate the distribution of the web-based survey. A roadmap to illustrate how this data collection process unfolded is presented, as well as several “lessons learned” during this journey. An explanation of the considerations that impacted the sampling design is provided. The goal of this case study is to provide researchers, including doctoral students, with realistic expectations and an awareness of the benefits and risks associated with the use of this method of data collection.

  13. Mixed Methods Sampling: A Typology with Examples

    Science.gov (United States)

    Teddlie, Charles; Yu, Fen

    2007-01-01

    This article presents a discussion of mixed methods (MM) sampling techniques. MM sampling involves combining well-established qualitative and quantitative techniques in creative ways to answer research questions posed by MM research designs. Several issues germane to MM sampling are presented including the differences between probability and…

  14. Bats from Fazenda Intervales, Southeastern Brazil: species account and comparison between different sampling methods

    Directory of Open Access Journals (Sweden)

    Christine V. Portfors

    2000-06-01

    Full Text Available Assessing the composition of an area's bat fauna is typically accomplished by using captures or by monitoring echolocation calls with bat detectors. The two methods may not provide the same data regarding species composition. Mist nets and harp traps may be biased towards sampling low flying species, and bat detectors biased towards detecting high intensity echolocators. A comparison of the bat fauna of Fazenda Intervales, southeastern Brazil, as revealed by mist nets and harp trap captures, checking roosts and by monitoring echolocation calls of flying bats illustrates this point. A total of 17 species of bats was sampled. Fourteen bat species were captured and the echolocation calls of 12 species were recorded, three of them not revealed by mist nets or harp traps. The different sampling methods provided different pictures of the bat fauna. Phyllostomid bats dominated the catches in mist nets, but in the field their echolocation calls were never detected. No single sampling approach provided a complete assessment of the bat fauna in the study area. In general, bats producing low intensity echolocation calls, such as phyllostomids, are more easily assessed by netting, and bats producing high intensity echolocation calls are better surveyed by bat detectors. The results demonstrate that a combined and varied approach to sampling is required for a complete assessment of the bat fauna of an area.

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

    Science.gov (United States)

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

    2017-06-01

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

  16. Log sampling methods and software for stand and landscape analyses.

    Science.gov (United States)

    Lisa J. Bate; Torolf R. Torgersen; Michael J. Wisdom; Edward O. Garton; Shawn C. Clabough

    2008-01-01

    We describe methods for efficient, accurate sampling of logs at landscape and stand scales to estimate density, total length, cover, volume, and weight. Our methods focus on optimizing the sampling effort by choosing an appropriate sampling method and transect length for specific forest conditions and objectives. Sampling methods include the line-intersect method and...

  17. 19 CFR 151.70 - Method of sampling by Customs.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Method of sampling by Customs. 151.70 Section 151... THE TREASURY (CONTINUED) EXAMINATION, SAMPLING, AND TESTING OF MERCHANDISE Wool and Hair § 151.70 Method of sampling by Customs. A general sample shall be taken from each sampling unit, unless it is not...

  18. Amostra mestra e geoprocessamento: tecnologias para inquéritos domiciliares Master sample and geoprocessing: technologies for household surveys

    Directory of Open Access Journals (Sweden)

    Nilza Nunes da Silva

    2003-08-01

    census enumeration areas in several epidemiological surveys using updated information from the National Survey of Households (PNAD. METHODS: Address data file comprising 72 census enumeration areas was kept as primary sampling units for the city of São Paulo. During the period 1995-2000, three distinct household samples were drawn using the two-stage cluster sampling procedure. Geographic Information System (GIS technology allowed delimiting boundaries, blocks and streets for any primary sampling unit and printing updated maps for selected sub-samples. RESULTS: Twenty-five thousand dwellings made up the permanent address data file of the master sample. A cheaper and quicker selection of each sample, plus gathering information on demographic and topographical profiles of census enumeration areas were the main contribution of the study results. CONCLUSIONS: The master sample concept, integrated with GIS technology, is an advantageous alternative sampling design for household surveys in urban areas. Using the list of addresses from the PNAD updated yearly, although limiting its application to the most populated Brazilian cities, avoids the need of creating an independent sampling procedure for each individual survey carried out in the period between demographic censuses, and it is an important contribution for planning sampling surveys in public health.

  19. Geochemical reanalysis of historical U.S. Geological Survey sediment samples from the Tonsina area, Valdez Quadrangle, Alaska

    Science.gov (United States)

    Werdon, Melanie B.; Granitto, Matthew; Azain, Jaime S.

    2015-01-01

    The State of Alaska’s Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska’s statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. As part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential. The USGS is also undertaking SCM-related geologic studies in Alaska through the federally funded Alaska Critical Minerals cooperative project. DGGS and USGS share the goal of evaluating Alaska’s strategic and critical minerals potential and together created a Letter of Agreement (signed December 2012) and a supplementary Technical Assistance Agreement (#14CMTAA143458) to facilitate the two agencies’ cooperative work. Under these agreements, DGGS contracted the USGS in Denver to reanalyze historical USGS sediment samples from Alaska. For this report, DGGS funded reanalysis of 128 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from the Tonsina area in the Chugach Mountains, Valdez quadrangle, Alaska (fig. 1). The USGS was responsible for sample retrieval from the National Geochemical Sample Archive (NGSA) in Denver, Colorado through the final quality assurance/quality control (QA/QC) of the geochemical analyses obtained through the USGS contract lab. The new geochemical data are published in this report as a coauthored DGGS report, and will be incorporated into the statewide geochemical databases of both agencies

  20. Survey method for radiological surveys of 300 FF-1 Operable Unit soil and materials

    International Nuclear Information System (INIS)

    Greif, A.A.

    1997-06-01

    This technical basis document is to be used to survey soils at the 300-FF-1 Operable Unit during remediation of the site. Its purpose is to provide a basis for the survey methods to be employed by the Radiological Control Technician to determine if excavated areas require continued remediation in accordance with the Record of Decision for the operable unit

  1. Comparison of sampling methods for hard-to-reach francophone populations: yield and adequacy of advertisement and respondent-driven sampling.

    Science.gov (United States)

    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.

  2. Innovative methods for inorganic sample preparation

    Energy Technology Data Exchange (ETDEWEB)

    Essling, A.M.; Huff, E.A.; Graczyk, D.G.

    1992-04-01

    Procedures and guidelines are given for the dissolution of a variety of selected materials using fusion, microwave, and Parr bomb techniques. These materials include germanium glass, corium-concrete mixtures, and zeolites. Emphasis is placed on sample-preparation approaches that produce a single master solution suitable for complete multielement characterization of the sample. In addition, data are presented on the soil microwave digestion method approved by the Environmental Protection Agency (EPA). Advantages and disadvantages of each sample-preparation technique are summarized.

  3. Innovative methods for inorganic sample preparation

    International Nuclear Information System (INIS)

    Essling, A.M.; Huff, E.A.; Graczyk, D.G.

    1992-04-01

    Procedures and guidelines are given for the dissolution of a variety of selected materials using fusion, microwave, and Parr bomb techniques. These materials include germanium glass, corium-concrete mixtures, and zeolites. Emphasis is placed on sample-preparation approaches that produce a single master solution suitable for complete multielement characterization of the sample. In addition, data are presented on the soil microwave digestion method approved by the Environmental Protection Agency (EPA). Advantages and disadvantages of each sample-preparation technique are summarized

  4. Shorlist Masterplan Wind. Evaluation of the sampling grid of the year-round ichthyoplankton survey

    NARCIS (Netherlands)

    Bolle, L.J.; Beek, van J.K.L.

    2011-01-01

    Within the research programme 'Shortlist Masterplan Wind' a year-round ichthyoplankton survey is being carried out. The sampling area is based on known spawning concentrations and prevailing currents.

  5. Chapter 12. Sampling and analytical methods

    International Nuclear Information System (INIS)

    Busenberg, E.; Plummer, L.N.; Cook, P.G.; Solomon, D.K.; Han, L.F.; Groening, M.; Oster, H.

    2006-01-01

    When water samples are taken for the analysis of CFCs, regardless of the sampling method used, contamination of samples by contact with atmospheric air (with its 'high' CFC concentrations) is a major concern. This is because groundwaters usually have lower CFC concentrations than those waters which have been exposed to the modern air. Some groundwaters might not contain CFCs and, therefore, are most sensitive to trace contamination by atmospheric air. Thus, extreme precautions are needed to obtain uncontaminated samples when groundwaters, particularly those with older ages, are sampled. It is recommended at the start of any CFC investigation that samples from a CFC-free source be collected and analysed, as a check upon the sampling equipment and methodology. The CFC-free source might be a deep monitoring well or, alternatively, CFC-free water could be carefully prepared in the laboratory. It is especially important that all tubing, pumps and connection that will be used in the sampling campaign be checked in this manner

  6. Engagement with HIV prevention treatment and care among female sex workers in Zimbabwe: a respondent driven sampling survey.

    Science.gov (United States)

    Cowan, Frances M; Mtetwa, Sibongile; Davey, Calum; Fearon, Elizabeth; Dirawo, Jeffrey; Wong-Gruenwald, Ramona; Ndikudze, Theresa; Chidiya, Samson; Benedikt, Clemens; Busza, Joanna; Hargreaves, James R

    2013-01-01

    To determine the HIV prevalence and extent of engagement with HIV prevention and care among a representative sample of Zimbabwean sex workers working in Victoria Falls, Hwange and Mutare. Respondent driven sampling (RDS) surveys conducted at each site. Sex workers were recruited using respondent driven sampling with each respondent limited to recruiting 2 peers. Participants completed an interviewer-administered questionnaire and provided a finger prick blood sample for HIV antibody testing. Statistical analysis took account of sampling method. 870 women were recruited from the three sites. HIV prevalence was between 50 and 70%. Around half of those confirmed HIV positive were aware of their HIV status and of those 50-70% reported being enrolled in HIV care programmes. Overall only 25-35% of those with laboratory-confirmed HIV were accessing antiretroviral therapy. Among those reporting they were HIV negative, 21-28% reported having an HIV test in the last 6 months. Of those tested HIV negative, most (65-82%) were unaware of their status. Around two-thirds of sex workers reported consistent condom use with their clients. As in other settings, sex workers reported high rates of gender based violence and police harassment. This survey suggests that prevalence of HIV is high among sex workers in Zimbabwe and that their engagement with prevention, treatment and care is sub-optimal. Intensifying prevention and care interventions for sex workers has the potential to markedly reduce HIV and social risks for sex workers, their clients and the general population in Zimbabwe and elsewhere in the region.

  7. Hospital survey on patient safety culture: psychometric analysis on a Scottish sample.

    Science.gov (United States)

    Sarac, Cakil; Flin, Rhona; Mearns, Kathryn; Jackson, Jeanette

    2011-10-01

    To investigate the psychometric properties of the Hospital Survey on Patient Safety Culture on a Scottish NHS data set. The data were collected from 1969 clinical staff (estimated 22% response rate) from one acute hospital from each of seven Scottish Health boards. Using a split-half validation technique, the data were randomly split; an exploratory factor analysis was conducted on the calibration data set, and confirmatory factor analyses were conducted on the validation data set to investigate and check the original US model fit in a Scottish sample. Following the split-half validation technique, exploratory factor analysis results showed a 10-factor optimal measurement model. The confirmatory factor analyses were then performed to compare the model fit of two competing models (10-factor alternative model vs 12-factor original model). An S-B scaled χ(2) square difference test demonstrated that the original 12-factor model performed significantly better in a Scottish sample. Furthermore, reliability analyses of each component yielded satisfactory results. The mean scores on the climate dimensions in the Scottish sample were comparable with those found in other European countries. This study provided evidence that the original 12-factor structure of the Hospital Survey on Patient Safety Culture scale has been replicated in this Scottish sample. Therefore, no modifications are required to the original 12-factor model, which is suggested for use, since it would allow researchers the possibility of cross-national comparisons.

  8. The outlier sample effects on multivariate statistical data processing geochemical stream sediment survey (Moghangegh region, North West of Iran)

    International Nuclear Information System (INIS)

    Ghanbari, Y.; Habibnia, A.; Memar, A.

    2009-01-01

    In geochemical stream sediment surveys in Moghangegh Region in north west of Iran, sheet 1:50,000, 152 samples were collected and after the analyze and processing of data, it revealed that Yb, Sc, Ni, Li, Eu, Cd, Co, as contents in one sample is far higher than other samples. After detecting this sample as an outlier sample, the effect of this sample on multivariate statistical data processing for destructive effects of outlier sample in geochemical exploration was investigated. Pearson and Spear man correlation coefficient methods and cluster analysis were used for multivariate studies and the scatter plot of some elements together the regression profiles are given in case of 152 and 151 samples and the results are compared. After investigation of multivariate statistical data processing results, it was realized that results of existence of outlier samples may appear as the following relations between elements: - true relation between two elements, which have no outlier frequency in the outlier sample. - false relation between two elements which one of them has outlier frequency in the outlier sample. - complete false relation between two elements which both have outlier frequency in the outlier sample

  9. Sampling methods for low-frequency electromagnetic imaging

    International Nuclear Information System (INIS)

    Gebauer, Bastian; Hanke, Martin; Schneider, Christoph

    2008-01-01

    For the detection of hidden objects by low-frequency electromagnetic imaging the linear sampling method works remarkably well despite the fact that the rigorous mathematical justification is still incomplete. In this work, we give an explanation for this good performance by showing that in the low-frequency limit the measurement operator fulfils the assumptions for the fully justified variant of the linear sampling method, the so-called factorization method. We also show how the method has to be modified in the physically relevant case of electromagnetic imaging with divergence-free currents. We present numerical results to illustrate our findings, and to show that similar performance can be expected for the case of conducting objects and layered backgrounds

  10. A loop-mediated isothermal amplification method for a differential identification of Taenia tapeworms from human: application to a field survey.

    Science.gov (United States)

    Nkouawa, Agathe; Sako, Yasuhito; Li, Tiaoying; Chen, Xingwang; Nakao, Minoru; Yanagida, Tetsuya; Okamoto, Munehiro; Giraudoux, Patrick; Raoul, Francis; Nakaya, Kazuhiro; Xiao, Ning; Qiu, Jiamin; Qiu, Dongchuan; Craig, Philip S; Ito, Akira

    2012-12-01

    In this study, we applied a loop-mediated isothermal amplification method for identification of human Taenia tapeworms in Tibetan communities in Sichuan, China. Out of 51 proglottids recovered from 35 carriers, 9, 1, and 41 samples were identified as Taenia solium, Taenia asiatica and Taenia saginata, respectively. Same results were obtained afterwards in the laboratory, except one sample. These results demonstrated that the LAMP method enabled rapid identification of parasites in the field surveys, which suggested that this method would contribute to the control of Taenia infections in endemic areas. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  11. Sampling of temporal networks: Methods and biases

    Science.gov (United States)

    Rocha, Luis E. C.; Masuda, Naoki; Holme, Petter

    2017-11-01

    Temporal networks have been increasingly used to model a diversity of systems that evolve in time; for example, human contact structures over which dynamic processes such as epidemics take place. A fundamental aspect of real-life networks is that they are sampled within temporal and spatial frames. Furthermore, one might wish to subsample networks to reduce their size for better visualization or to perform computationally intensive simulations. The sampling method may affect the network structure and thus caution is necessary to generalize results based on samples. In this paper, we study four sampling strategies applied to a variety of real-life temporal networks. We quantify the biases generated by each sampling strategy on a number of relevant statistics such as link activity, temporal paths and epidemic spread. We find that some biases are common in a variety of networks and statistics, but one strategy, uniform sampling of nodes, shows improved performance in most scenarios. Given the particularities of temporal network data and the variety of network structures, we recommend that the choice of sampling methods be problem oriented to minimize the potential biases for the specific research questions on hand. Our results help researchers to better design network data collection protocols and to understand the limitations of sampled temporal network data.

  12. Sample substitution can be an acceptable data-collection strategy: the case of the Belgian Health Interview Survey.

    Science.gov (United States)

    Demarest, Stefaan; Molenberghs, Geert; Van der Heyden, Johan; Gisle, Lydia; Van Oyen, Herman; de Waleffe, Sandrine; Van Hal, Guido

    2017-11-01

    Substitution of non-participating households is used in the Belgian Health Interview Survey (BHIS) as a method to obtain the predefined net sample size. Yet, possible effects of applying substitution on response rates and health estimates remain uncertain. In this article, the process of substitution with its impact on response rates and health estimates is assessed. The response rates (RR)-both at household and individual level-according to the sampling criteria were calculated for each stage of the substitution process, together with the individual accrual rate (AR). Unweighted and weighted health estimates were calculated before and after applying substitution. Of the 10,468 members of 4878 initial households, 5904 members (RRind: 56.4%) of 2707 households (RRhh: 55.5%) participated. For the three successive (matched) substitutes, the RR dropped to 45%. The composition of the net sample resembles the one of the initial samples. Applying substitution did not produce any important distorting effects on the estimates. Applying substitution leads to an increase in non-participation, but does not impact the estimations.

  13. An improved selective sampling method

    International Nuclear Information System (INIS)

    Miyahara, Hiroshi; Iida, Nobuyuki; Watanabe, Tamaki

    1986-01-01

    The coincidence methods which are currently used for the accurate activity standardisation of radio-nuclides, require dead time and resolving time corrections which tend to become increasingly uncertain as countrates exceed about 10 K. To reduce the dependence on such corrections, Muller, in 1981, proposed the selective sampling method using a fast multichannel analyser (50 ns ch -1 ) for measuring the countrates. It is, in many ways, more convenient and possibly potentially more reliable to replace the MCA with scalers and a circuit is described employing five scalers; two of them serving to measure the background correction. Results of comparisons using our new method and the coincidence method for measuring the activity of 60 Co sources yielded agree-ment within statistical uncertainties. (author)

  14. An algorithm to improve sampling efficiency for uncertainty propagation using sampling based method

    International Nuclear Information System (INIS)

    Campolina, Daniel; Lima, Paulo Rubens I.; Pereira, Claubia; Veloso, Maria Auxiliadora F.

    2015-01-01

    Sample size and computational uncertainty were varied in order to investigate sample efficiency and convergence of the sampling based method for uncertainty propagation. Transport code MCNPX was used to simulate a LWR model and allow the mapping, from uncertain inputs of the benchmark experiment, to uncertain outputs. Random sampling efficiency was improved through the use of an algorithm for selecting distributions. Mean range, standard deviation range and skewness were verified in order to obtain a better representation of uncertainty figures. Standard deviation of 5 pcm in the propagated uncertainties for 10 n-samples replicates was adopted as convergence criterion to the method. Estimation of 75 pcm uncertainty on reactor k eff was accomplished by using sample of size 93 and computational uncertainty of 28 pcm to propagate 1σ uncertainty of burnable poison radius. For a fixed computational time, in order to reduce the variance of the uncertainty propagated, it was found, for the example under investigation, it is preferable double the sample size than double the amount of particles followed by Monte Carlo process in MCNPX code. (author)

  15. Human-Robot Site Survey and Sampling for Space Exploration

    Science.gov (United States)

    Fong, Terrence; Bualat, Maria; Edwards, Laurence; Flueckiger, Lorenzo; Kunz, Clayton; Lee, Susan Y.; Park, Eric; To, Vinh; Utz, Hans; Ackner, Nir

    2006-01-01

    NASA is planning to send humans and robots back to the Moon before 2020. In order for extended missions to be productive, high quality maps of lunar terrain and resources are required. Although orbital images can provide much information, many features (local topography, resources, etc) will have to be characterized directly on the surface. To address this need, we are developing a system to perform site survey and sampling. The system includes multiple robots and humans operating in a variety of team configurations, coordinated via peer-to-peer human-robot interaction. In this paper, we present our system design and describe planned field tests.

  16. DOE methods for evaluating environmental and waste management samples

    International Nuclear Information System (INIS)

    Goheen, S.C.; McCulloch, M.; Thomas, B.L.; Riley, R.G.; Sklarew, D.S.; Mong, G.M.; Fadeff, S.K.

    1994-04-01

    DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) is a resource intended to support sampling and analytical activities for the evaluation of environmental and waste management samples from U.S. Department of Energy (DOE) sites. DOE Methods is the result of extensive cooperation from all DOE analytical laboratories. All of these laboratories have contributed key information and provided technical reviews as well as significant moral support leading to the success of this document. DOE Methods is designed to encompass methods for collecting representative samples and for determining the radioisotope activity and organic and inorganic composition of a sample. These determinations will aid in defining the type and breadth of contamination and thus determine the extent of environmental restoration or waste management actions needed, as defined by the DOE, the U.S. Environmental Protection Agency, or others. The development of DOE Methods is supported by the Laboratory Management Division of the DOE. Methods are prepared for entry into DOE Methods as chapter editors, together with DOE and other participants in this program, identify analytical and sampling method needs. Unique methods or methods consolidated from similar procedures in the DOE Procedures Database are selected for potential inclusion in this document. Initial selection is based largely on DOE needs and procedure applicability and completeness. Methods appearing in this document are one of two types. open-quotes Draftclose quotes or open-quotes Verified.close quotes. open-quotes Draftclose quotes methods that have been reviewed internally and show potential for eventual verification are included in this document, but they have not been reviewed externally, and their precision and bias may not be known. open-quotes Verifiedclose quotes methods in DOE Methods have been reviewed by volunteers from various DOE sites and private corporations

  17. A Method for Choosing the Best Samples for Mars Sample Return.

    Science.gov (United States)

    Gordon, Peter R; Sephton, Mark A

    2018-05-01

    Success of a future Mars Sample Return mission will depend on the correct choice of samples. Pyrolysis-FTIR can be employed as a triage instrument for Mars Sample Return. The technique can thermally dissociate minerals and organic matter for detection. Identification of certain mineral types can determine the habitability of the depositional environment, past or present, while detection of organic matter may suggest past or present habitation. In Mars' history, the Theiikian era represents an attractive target for life search missions and the acquisition of samples. The acidic and increasingly dry Theiikian may have been habitable and followed a lengthy neutral and wet period in Mars' history during which life could have originated and proliferated to achieve relatively abundant levels of biomass with a wide distribution. Moreover, the sulfate minerals produced in the Theiikian are also known to be good preservers of organic matter. We have used pyrolysis-FTIR and samples from a Mars analog ferrous acid stream with a thriving ecosystem to test the triage concept. Pyrolysis-FTIR identified those samples with the greatest probability of habitability and habitation. A three-tier scoring system was developed based on the detection of (i) organic signals, (ii) carbon dioxide and water, and (iii) sulfur dioxide. The presence of each component was given a score of A, B, or C depending on whether the substance had been detected, tentatively detected, or not detected, respectively. Single-step (for greatest possible sensitivity) or multistep (for more diagnostic data) pyrolysis-FTIR methods informed the assignments. The system allowed the highest-priority samples to be categorized as AAA (or A*AA if the organic signal was complex), while the lowest-priority samples could be categorized as CCC. Our methods provide a mechanism with which to rank samples and identify those that should take the highest priority for return to Earth during a Mars Sample Return mission. Key Words

  18. Small-vessel Survey and Auction Sampling to Estimate Growth and Maturity of Eteline Snappers

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Small-vessel Survey and Auction Sampling to Estimate Growth and Maturity of Eteline Snappers and Improve Data-Limited Stock Assessments. This biosampling project...

  19. Sample preparation method for scanning force microscopy

    CERN Document Server

    Jankov, I R; Szente, R N; Carreno, M N P; Swart, J W; Landers, R

    2001-01-01

    We present a method of sample preparation for studies of ion implantation on metal surfaces. The method, employing a mechanical mask, is specially adapted for samples analysed by Scanning Force Microscopy. It was successfully tested on polycrystalline copper substrates implanted with phosphorus ions at an acceleration voltage of 39 keV. The changes of the electrical properties of the surface were measured by Kelvin Probe Force Microscopy and the surface composition was analysed by Auger Electron Spectroscopy.

  20. Optimal power flow: a bibliographic survey II. Non-deterministic and hybrid methods

    Energy Technology Data Exchange (ETDEWEB)

    Frank, Stephen [Colorado School of Mines, Department of Electrical Engineering and Computer Science, Golden, CO (United States); Steponavice, Ingrida [Univ. of Jyvaskyla, Dept. of Mathematical Information Technology, Agora (Finland); Rebennack, Steffen [Colorado School of Mines, Division of Economics and Business, Golden, CO (United States)

    2012-09-15

    Over the past half-century, optimal power flow (OPF) has become one of the most important and widely studied nonlinear optimization problems. In general, OPF seeks to optimize the operation of electric power generation, transmission, and distribution networks subject to system constraints and control limits. Within this framework, however, there is an extremely wide variety of OPF formulations and solution methods. Moreover, the nature of OPF continues to evolve due to modern electricity markets and renewable resource integration. In this two-part survey, we survey both the classical and recent OPF literature in order to provide a sound context for the state of the art in OPF formulation and solution methods. The survey contributes a comprehensive discussion of specific optimization techniques that have been applied to OPF, with an emphasis on the advantages, disadvantages, and computational characteristics of each. Part I of the survey provides an introduction and surveys the deterministic optimization methods that have been applied to OPF. Part II of the survey (this article) examines the recent trend towards stochastic, or non-deterministic, search techniques and hybrid methods for OPF. (orig.)

  1. Ochratoxin A in raisins and currants: basic extraction procedure used in two small marketing surveys of the occurrence and control of the heterogeneity of the toxins in samples.

    Science.gov (United States)

    Möller, T E; Nyberg, M

    2003-11-01

    A basic extraction procedure for analysis of ochratoxin A (OTA) in currants and raisins is described, as well as the occurrence of OTA and a control of heterogeneity of the toxin in samples bought for two small marketing surveys 1999/2000 and 2001/02. Most samples in the surveys were divided into two subsamples that were individually prepared as slurries and analysed separately. The limit of quantification for the method was estimated as 0.1 microg kg(-1) and recoveries of 85, 90 and 115% were achieved in recovery experiments at 10, 5 and 0.1 microg kg(-1), respectively. Of all 118 subsamples analysed in the surveys, 96 (84%) contained ochratoxin A at levels above the quantification level and five samples (4%) contained more than the European Community legislation of 10 microg kg(-1). The OTA concentrations found in the first survey were in the range Big differences were often achieved between individual subsamples of the original sample, which indicate a wide heterogeneous distribution of the toxin. Data from the repeatability test as well as recovery experiments from the same slurries showed that preparation of slurries as described here seemed to give a homogeneous and representative sample. The extraction with the basic sodium bicarbonate-methanol mixture used in the surveys gave similar or somewhat higher OTA values on some samples tested in a comparison with a weak phosphoric acid water-methanol extraction mixture.

  2. Does the underground sidewall station survey method meet MHSA ...

    African Journals Online (AJOL)

    The question is asked whether or not this method of sur-veying will meet the MHSA standards of accuracy that was developed for typical hangingwall traverse type networks. Results obtained from a survey closure using a network of clusters of four sidewall stations demonstrates that under the described circumstances it will ...

  3. National sample survey to assess the new case disease burden of leprosy in India

    Directory of Open Access Journals (Sweden)

    Kiran Katoch

    2017-01-01

    Full Text Available A national sample survey of leprosy was undertaken in partnership with Indian Council of Medical Research (ICMR institutions, National Leprosy Eradication Programme (NLEP, Panchayati Raj members, and treated leprosy patients to detect new cases of leprosy in India. The objectives of the survey were to estimate the new leprosy case load; record both Grade 1 and Grade 2 disabilities in the new cases; and to assess the magnitude of stigma and discrimination prevalent in the society. A cluster based, cross-sectional survey involving all States was used for the door-to-door survey using inverse sampling methodology. Rural and urban clusters were sampled separately. The population screened for detecting 28 new cases in rural and 30 in urban clusters was enumerated, recorded and analyzed. Data capture and analysis in different schedules were the main tools used. For quality control three tiers of experts were utilized for the confirmation of cases and disabilities. Self-stigma was assessed in more than half of the total new patients detected with disabilities by the approved questionnaire. A different questionnaire was used to assess the stigma in the community. A population of 14,725,525 (10,302,443 rural; 4,423,082 urban was screened and 2161 new cases - 1300 paucibacillary (PB and 861 multibacillary (MB were detected. New case estimates for leprosy was 330,346 (95% Confidence limits, 287,445-380,851. Disabilities observed in these cases were 2.05/100,000 population and 13.9 per cent (302/2161 in new cases. Self-stigma in patients with disabilities was reduced, and the patients were well accepted by the spouse, neighbour, at workplace and in social functions.

  4. Sampling and analysis methods for geothermal fluids and gases

    Energy Technology Data Exchange (ETDEWEB)

    Watson, J.C.

    1978-07-01

    The sampling procedures for geothermal fluids and gases include: sampling hot springs, fumaroles, etc.; sampling condensed brine and entrained gases; sampling steam-lines; low pressure separator systems; high pressure separator systems; two-phase sampling; downhole samplers; and miscellaneous methods. The recommended analytical methods compiled here cover physical properties, dissolved solids, and dissolved and entrained gases. The sequences of methods listed for each parameter are: wet chemical, gravimetric, colorimetric, electrode, atomic absorption, flame emission, x-ray fluorescence, inductively coupled plasma-atomic emission spectroscopy, ion exchange chromatography, spark source mass spectrometry, neutron activation analysis, and emission spectrometry. Material on correction of brine component concentrations for steam loss during flashing is presented. (MHR)

  5. The use of qualitative methods to inform Delphi surveys in core outcome set development.

    Science.gov (United States)

    Keeley, T; Williamson, P; Callery, P; Jones, L L; Mathers, J; Jones, J; Young, B; Calvert, M

    2016-05-04

    Core outcome sets (COS) help to minimise bias in trials and facilitate evidence synthesis. Delphi surveys are increasingly being used as part of a wider process to reach consensus about what outcomes should be included in a COS. Qualitative research can be used to inform the development of Delphi surveys. This is an advance in the field of COS development and one which is potentially valuable; however, little guidance exists for COS developers on how best to use qualitative methods and what the challenges are. This paper aims to provide early guidance on the potential role and contribution of qualitative research in this area. We hope the ideas we present will be challenged, critiqued and built upon by others exploring the role of qualitative research in COS development. This paper draws upon the experiences of using qualitative methods in the pre-Delphi stage of the development of three different COS. Using these studies as examples, we identify some of the ways that qualitative research might contribute to COS development, the challenges in using such methods and areas where future research is required. Qualitative research can help to identify what outcomes are important to stakeholders; facilitate understanding of why some outcomes may be more important than others, determine the scope of outcomes; identify appropriate language for use in the Delphi survey and inform comparisons between stakeholder data and other sources, such as systematic reviews. Developers need to consider a number of methodological points when using qualitative research: specifically, which stakeholders to involve, how to sample participants, which data collection methods are most appropriate, how to consider outcomes with stakeholders and how to analyse these data. A number of areas for future research are identified. Qualitative research has the potential to increase the research community's confidence in COS, although this will be dependent upon using rigorous and appropriate

  6. Survey Shows Variation in Ph.D. Methods Training.

    Science.gov (United States)

    Steeves, Leslie; And Others

    1983-01-01

    Reports on a 1982 survey of journalism graduate studies indicating considerable variation in research methods requirements and emphases in 23 universities offering doctoral degrees in mass communication. (HOD)

  7. Regional soil erosion assessment based on a sample survey and geostatistics

    Science.gov (United States)

    Yin, Shuiqing; Zhu, Zhengyuan; Wang, Li; Liu, Baoyuan; Xie, Yun; Wang, Guannan; Li, Yishan

    2018-03-01

    Soil erosion is one of the most significant environmental problems in China. From 2010 to 2012, the fourth national census for soil erosion sampled 32 364 PSUs (Primary Sampling Units, small watersheds) with the areas of 0.2-3 km2. Land use and soil erosion controlling factors including rainfall erosivity, soil erodibility, slope length, slope steepness, biological practice, engineering practice, and tillage practice for the PSUs were surveyed, and the soil loss rate for each land use in the PSUs was estimated using an empirical model, the Chinese Soil Loss Equation (CSLE). Though the information collected from the sample units can be aggregated to estimate soil erosion conditions on a large scale; the problem of estimating soil erosion condition on a regional scale has not been addressed well. The aim of this study is to introduce a new model-based regional soil erosion assessment method combining a sample survey and geostatistics. We compared seven spatial interpolation models based on the bivariate penalized spline over triangulation (BPST) method to generate a regional soil erosion assessment from the PSUs. Shaanxi Province (3116 PSUs) in China was selected for the comparison and assessment as it is one of the areas with the most serious erosion problem. Ten-fold cross-validation based on the PSU data showed the model assisted by the land use, rainfall erosivity factor (R), soil erodibility factor (K), slope steepness factor (S), and slope length factor (L) derived from a 1 : 10 000 topography map is the best one, with the model efficiency coefficient (ME) being 0.75 and the MSE being 55.8 % of that for the model assisted by the land use alone. Among four erosion factors as the covariates, the S factor contributed the most information, followed by K and L factors, and R factor made almost no contribution to the spatial estimation of soil loss. The LS factor derived from 30 or 90 m Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) data

  8. An UAV scheduling and planning method for post-disaster survey

    Science.gov (United States)

    Li, G. Q.; Zhou, X. G.; Yin, J.; Xiao, Q. Y.

    2014-11-01

    Annually, the extreme climate and special geological environments lead to frequent natural disasters, e.g., earthquakes, floods, etc. The disasters often bring serious casualties and enormous economic losses. Post-disaster surveying is very important for disaster relief and assessment. As the Unmanned Aerial Vehicle (UAV) remote sensing with the advantage of high efficiency, high precision, high flexibility, and low cost, it is widely used in emergency surveying in recent years. As the UAVs used in emergency surveying cannot stop and wait for the happening of the disaster, when the disaster happens the UAVs usually are working at everywhere. In order to improve the emergency surveying efficiency, it is needed to track the UAVs and assign the emergency surveying task for each selected UAV. Therefore, a UAV tracking and scheduling method for post-disaster survey is presented in this paper. In this method, Global Positioning System (GPS), and GSM network are used to track the UAVs; an emergency tracking UAV information database is built in advance by registration, the database at least includes the following information, e.g., the ID of the UAVs, the communication number of the UAVs; when catastrophe happens, the real time location of all UAVs in the database will be gotten using emergency tracking method at first, then the traffic cost time for all UAVs to the disaster region will be calculated based on the UAVs' the real time location and the road network using the nearest services analysis algorithm; the disaster region is subdivided to several emergency surveying regions based on DEM, area, and the population distribution map; the emergency surveying regions are assigned to the appropriated UAV according to shortest cost time rule. The UAVs tracking and scheduling prototype is implemented using SQLServer2008, ArcEnginge 10.1 SDK, Visual Studio 2010 C#, Android, SMS Modem, and Google Maps API.

  9. On Angular Sampling Methods for 3-D Spatial Channel Models

    DEFF Research Database (Denmark)

    Fan, Wei; Jämsä, Tommi; Nielsen, Jesper Ødum

    2015-01-01

    This paper discusses generating three dimensional (3D) spatial channel models with emphasis on the angular sampling methods. Three angular sampling methods, i.e. modified uniform power sampling, modified uniform angular sampling, and random pairing methods are proposed and investigated in detail....... The random pairing method, which uses only twenty sinusoids in the ray-based model for generating the channels, presents good results if the spatial channel cluster is with a small elevation angle spread. For spatial clusters with large elevation angle spreads, however, the random pairing method would fail...... and the other two methods should be considered....

  10. Prevalence of dementia-associated disability among Chinese older adults: results from a national sample survey.

    Science.gov (United States)

    Li, Ning; Zhang, Lei; Du, Wei; Pang, Lihua; Guo, Chao; Chen, Gong; Zheng, Xiaoying

    2015-03-01

    Due to rapid population aging and a tidal wave of dementia, dementia has become an urgent public health issue in China. Few large-scale surveys on dementia have been conducted in China and little was known about the magnitude of dysfunction and disability caused by dementia. In this study, using national sample survey data, we aimed to describe the prevalence rate of dementia-associated disability, its associated factors, and daily activities and social functions of people with dementia-associated disability in Chinese older adults. We used the second China National Sample Survey on Disability, comprising 2,526,145 persons from 771,797 households. Identification for dementia was based on consensus manuals. Standard weighting procedures were used to construct sample weights considering the multistage stratified cluster sampling survey scheme. Population weighted numbers, weighted prevalence, and the odd ratios (ORs) were calculated. The prevalence rate of dementia-associated disability was 4.64% (95% CI: 4.26-5.01) and it accounted for 41.03% of mental disability among Chinese older adults. Urban residence (OR: 1.33 [1.12-1.57]), older age (80+ years) (OR: 4.12 [3.38-.03]), illiteracy (OR: 1.79 [1.27-2.53]), and currently not married (OR: 1.15 [1.00-1.32]) were associated with increased risk of dementia-associated disability. Compared with those with mental disability of other causes and those with other types of disabilities, older adults with dementia-asscoiated disability were more likely to have severe or extreme difficulty in daily activities and social functions. Countermeasures are warranted to obtain a more precise overview of dementia in China, and strategies on enhancing early identification, treatment, and rehabilitation should be developed for people with dementia. Copyright © 2015 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

  11. The ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES) . I. Project description, survey sample, and quality assessment

    Science.gov (United States)

    Cox, Nick L. J.; Cami, Jan; Farhang, Amin; Smoker, Jonathan; Monreal-Ibero, Ana; Lallement, Rosine; Sarre, Peter J.; Marshall, Charlotte C. M.; Smith, Keith T.; Evans, Christopher J.; Royer, Pierre; Linnartz, Harold; Cordiner, Martin A.; Joblin, Christine; van Loon, Jacco Th.; Foing, Bernard H.; Bhatt, Neil H.; Bron, Emeric; Elyajouri, Meriem; de Koter, Alex; Ehrenfreund, Pascale; Javadi, Atefeh; Kaper, Lex; Khosroshadi, Habib G.; Laverick, Mike; Le Petit, Franck; Mulas, Giacomo; Roueff, Evelyne; Salama, Farid; Spaans, Marco

    2017-10-01

    The carriers of the diffuse interstellar bands (DIBs) are largely unidentified molecules ubiquitously present in the interstellar medium (ISM). After decades of study, two strong and possibly three weak near-infrared DIBs have recently been attributed to the C60^+ fullerene based on observational and laboratory measurements. There is great promise for the identification of the over 400 other known DIBs, as this result could provide chemical hints towards other possible carriers. In an effort tosystematically study the properties of the DIB carriers, we have initiated a new large-scale observational survey: the ESO Diffuse Interstellar Bands Large Exploration Survey (EDIBLES). The main objective is to build on and extend existing DIB surveys to make a major step forward in characterising the physical and chemical conditions for a statistically significant sample of interstellar lines-of-sight, with the goal to reverse-engineer key molecular properties of the DIB carriers. EDIBLES is a filler Large Programme using the Ultraviolet and Visual Echelle Spectrograph at the Very Large Telescope at Paranal, Chile. It is designed to provide an observationally unbiased view of the presence and behaviour of the DIBs towards early-spectral-type stars whose lines-of-sight probe the diffuse-to-translucent ISM. Such a complete dataset will provide a deep census of the atomic and molecular content, physical conditions, chemical abundances and elemental depletion levels for each sightline. Achieving these goals requires a homogeneous set of high-quality data in terms of resolution (R 70 000-100 000), sensitivity (S/N up to 1000 per resolution element), and spectral coverage (305-1042 nm), as well as a large sample size (100+ sightlines). In this first paper the goals, objectives and methodology of the EDIBLES programme are described and an initial assessment of the data is provided.

  12. Dead or Alive? Dealing with Unknown Eligibility in Longitudinal Surveys

    Directory of Open Access Journals (Sweden)

    Watson Nicole

    2016-12-01

    Full Text Available Longitudinal surveys follow people over time and some of these people will die during the life of the panel. Through fieldwork effort, some deaths will be reported or known, but others will be unobserved due to sample members no longer being issued to field or having inconclusive fieldwork outcomes (such as a noncontact that is not followed by a contact at a later wave. The coverage of deaths identified among sample members has flow-on implications to nonresponse correction. Using the Household, Income and Labour Dynamics in Australia (HILDA Survey, four methods are used to examine the extent of missing death reports. The first method matches the sample to the national death register. The second method uses life-expectancy tables to extrapolate the expected number of deaths among the sample with unknown eligibility. The third method is similar but models deaths from data internal to the survey. The fourth method models deaths as part of the attrition process of a longitudinal survey. The last three methods are compared to the first method and the implications for the construction of balanced panel weights and subsequent population inference are explored.

  13. A Survey of Formal Methods in Software Development

    DEFF Research Database (Denmark)

    Bjørner, Dines

    2012-01-01

    The use of formal methods and formal techniques in industry is steadily growing. In this survey we shall characterise what we mean by software development and by a formal method; briefly overview a history of formal specification languages - some of which are: VDM (Vienna Development Method, 1974...... need for multi-language formalisation (Petri Nets, MSC, StateChart, Temporal Logics); the sociology of university and industry acceptance of formal methods; the inevitability of the use of formal software development methods; while referring to seminal monographs and textbooks on formal methods....

  14. Effects of sample survey design on the accuracy of classification tree models in species distribution models

    Science.gov (United States)

    Thomas C. Edwards; D. Richard Cutler; Niklaus E. Zimmermann; Linda Geiser; Gretchen G. Moisen

    2006-01-01

    We evaluated the effects of probabilistic (hereafter DESIGN) and non-probabilistic (PURPOSIVE) sample surveys on resultant classification tree models for predicting the presence of four lichen species in the Pacific Northwest, USA. Models derived from both survey forms were assessed using an independent data set (EVALUATION). Measures of accuracy as gauged by...

  15. Survey of electronic payment methods and systems

    NARCIS (Netherlands)

    Havinga, Paul J.M.; Smit, Gerardus Johannes Maria; Helme, A.; Verbraeck, A.

    1996-01-01

    In this paper an overview of electronic payment methods and systems is given. This survey is done as part of the Moby Dick project. Electronic payment systems can be grouped into three broad classes: traditional money transactions, digital currency and creditdebit payments. Such payment systems have

  16. Interval sampling methods and measurement error: a computer simulation.

    Science.gov (United States)

    Wirth, Oliver; Slaven, James; Taylor, Matthew A

    2014-01-01

    A simulation study was conducted to provide a more thorough account of measurement error associated with interval sampling methods. A computer program simulated the application of momentary time sampling, partial-interval recording, and whole-interval recording methods on target events randomly distributed across an observation period. The simulation yielded measures of error for multiple combinations of observation period, interval duration, event duration, and cumulative event duration. The simulations were conducted up to 100 times to yield measures of error variability. Although the present simulation confirmed some previously reported characteristics of interval sampling methods, it also revealed many new findings that pertain to each method's inherent strengths and weaknesses. The analysis and resulting error tables can help guide the selection of the most appropriate sampling method for observation-based behavioral assessments. © Society for the Experimental Analysis of Behavior.

  17. Estimating health expectancies from two cross-sectional surveys: The intercensal method

    Directory of Open Access Journals (Sweden)

    Michel Guillot

    2009-10-01

    Full Text Available Health expectancies are key indicators for monitoring the health of populations, as well as for informing debates about compression or expansion of morbidity. However, current methodologies for estimating them are not entirely satisfactory. They are either of limited applicability because of high data requirements (the multistate method or based on questionable assumptions (the Sullivan method. This paper proposes a new method, called the "intercensal" method, which relies on the multistate framework but uses widely available data. The method uses age-specific proportions "healthy" at two successive, independent cross-sectional health surveys, and, together with information on general mortality, solves for the set of transition probabilities that produces the observed sequence of proportions healthy. The system is solved by making realistic parametric assumptions about the age patterns of transition probabilities. Using data from the Health and Retirement Survey (HRS and from the National Health Interview Survey (NHIS, the method is tested against both the multistate method and the Sullivan method. We conclude that the intercensal approach is a promising framework for the indirect estimation of health expectancies.

  18. Off-road sampling reveals a different grassland bird community than roadside sampling: implications for survey design and estimates to guide conservation

    Directory of Open Access Journals (Sweden)

    Troy I. Wellicome

    2014-06-01

    concern. Our results highlight the need to develop appropriate corrections for bias in estimates derived from roadside sampling, and the need to design surveys that sample bird communities across a more representative cross-section of the landscape, both near and far from roads.

  19. Wet-digestion of environmental sample using silver-mediated electrochemical method

    International Nuclear Information System (INIS)

    Kuwabara, Jun

    2010-01-01

    An application of silver-mediated electrochemical method to environmental samples as the effective digestion method for iodine analysis was tried. Usual digestion method for 129 I in many type of environmental sample is combustion method using quartz glass tube. Chemical yield of iodine on the combustion method reduce depending on the type of sample. The silver-mediated electrochemical method is expected to achieve very low loss of iodine. In this study, dried kombu (Laminaria) sample was tried to digest with electrochemical cell. At the case of 1g of sample, digestion was completed for about 24 hours under the electric condition of <10V and <2A. After the digestion, oxidized species of iodine was reduced to iodide by adding sodium sulfite. And then the precipitate of silver iodide was obtained. (author)

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

    International Nuclear Information System (INIS)

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

    1997-01-01

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

  1. DOE methods for evaluating environmental and waste management samples

    Energy Technology Data Exchange (ETDEWEB)

    Goheen, S.C.; McCulloch, M.; Thomas, B.L.; Riley, R.G.; Sklarew, D.S.; Mong, G.M.; Fadeff, S.K. [eds.

    1994-10-01

    DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) is a resource intended to support sampling and analytical activities for the evaluation of environmental and waste management samples from U.S. Department of Energy (DOE) sites. DOE Methods is the result of extensive cooperation from all DOE analytical laboratories. All of these laboratories have contributed key information and provided technical reviews as well as significant moral support leading to the success of this document. DOE Methods is designed to encompass methods for collecting representative samples and for determining the radioisotope activity and organic and inorganic composition of a sample. These determinations will aid in defining the type and breadth of contamination and thus determine the extent of environmental restoration or waste management actions needed, as defined by the DOE, the U.S. Environmental Protection Agency, or others. The development of DOE Methods is supported by the Analytical Services Division of DOE. Unique methods or methods consolidated from similar procedures in the DOE Procedures Database are selected for potential inclusion in this document. Initial selection is based largely on DOE needs and procedure applicability and completeness. Methods appearing in this document are one of two types, {open_quotes}Draft{close_quotes} or {open_quotes}Verified{close_quotes}. {open_quotes}Draft{close_quotes} methods that have been reviewed internally and show potential for eventual verification are included in this document, but they have not been reviewed externally, and their precision and bias may not be known. {open_quotes}Verified{close_quotes} methods in DOE Methods have been reviewed by volunteers from various DOE sites and private corporations. These methods have delineated measures of precision and accuracy.

  2. DOE methods for evaluating environmental and waste management samples

    International Nuclear Information System (INIS)

    Goheen, S.C.; McCulloch, M.; Thomas, B.L.; Riley, R.G.; Sklarew, D.S.; Mong, G.M.; Fadeff, S.K.

    1994-10-01

    DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) is a resource intended to support sampling and analytical activities for the evaluation of environmental and waste management samples from U.S. Department of Energy (DOE) sites. DOE Methods is the result of extensive cooperation from all DOE analytical laboratories. All of these laboratories have contributed key information and provided technical reviews as well as significant moral support leading to the success of this document. DOE Methods is designed to encompass methods for collecting representative samples and for determining the radioisotope activity and organic and inorganic composition of a sample. These determinations will aid in defining the type and breadth of contamination and thus determine the extent of environmental restoration or waste management actions needed, as defined by the DOE, the U.S. Environmental Protection Agency, or others. The development of DOE Methods is supported by the Analytical Services Division of DOE. Unique methods or methods consolidated from similar procedures in the DOE Procedures Database are selected for potential inclusion in this document. Initial selection is based largely on DOE needs and procedure applicability and completeness. Methods appearing in this document are one of two types, open-quotes Draftclose quotes or open-quotes Verifiedclose quotes. open-quotes Draftclose quotes methods that have been reviewed internally and show potential for eventual verification are included in this document, but they have not been reviewed externally, and their precision and bias may not be known. open-quotes Verifiedclose quotes methods in DOE Methods have been reviewed by volunteers from various DOE sites and private corporations. These methods have delineated measures of precision and accuracy

  3. Neutron activation analysis of certified samples by the absolute method

    Science.gov (United States)

    Kadem, F.; Belouadah, N.; Idiri, Z.

    2015-07-01

    The nuclear reactions analysis technique is mainly based on the relative method or the use of activation cross sections. In order to validate nuclear data for the calculated cross section evaluated from systematic studies, we used the neutron activation analysis technique (NAA) to determine the various constituent concentrations of certified samples for animal blood, milk and hay. In this analysis, the absolute method is used. The neutron activation technique involves irradiating the sample and subsequently performing a measurement of the activity of the sample. The fundamental equation of the activation connects several physical parameters including the cross section that is essential for the quantitative determination of the different elements composing the sample without resorting to the use of standard sample. Called the absolute method, it allows a measurement as accurate as the relative method. The results obtained by the absolute method showed that the values are as precise as the relative method requiring the use of standard sample for each element to be quantified.

  4. THE USE OF RANKING SAMPLING METHOD WITHIN MARKETING RESEARCH

    Directory of Open Access Journals (Sweden)

    CODRUŢA DURA

    2011-01-01

    Full Text Available Marketing and statistical literature available to practitioners provides a wide range of sampling methods that can be implemented in the context of marketing research. Ranking sampling method is based on taking apart the general population into several strata, namely into several subdivisions which are relatively homogenous regarding a certain characteristic. In fact, the sample will be composed by selecting, from each stratum, a certain number of components (which can be proportional or non-proportional to the size of the stratum until the pre-established volume of the sample is reached. Using ranking sampling within marketing research requires the determination of some relevant statistical indicators - average, dispersion, sampling error etc. To that end, the paper contains a case study which illustrates the actual approach used in order to apply the ranking sample method within a marketing research made by a company which provides Internet connection services, on a particular category of customers – small and medium enterprises.

  5. The VA Ostomy Health-Related Quality of Life Study: objectives, methods, and patient sample.

    Science.gov (United States)

    Krouse, Robert S; Mohler, M Jane; Wendel, Christopher S; Grant, Marcia; Baldwin, Carol M; Rawl, Susan M; McCorkle, Ruth; Rosenfeld, Kenneth E; Ko, Clifford Y; Schmidt, C Max; Coons, Stephen Joel

    2006-04-01

    To present the design and methods of a multisite study of health-related quality of life (HR-QOL) in veterans living with ostomies. Veterans from Tucson, Indianapolis, and Los Angeles VA Medical Centers were surveyed using the validated City of Hope ostomy-specific tool (mCOH-QOL-Ostomy) and the SF-36V. Cases (ostomates) had a major gastrointestinal procedure that required an intestinal stoma, while controls had similar procedures for which an ostomy was not required. Ostomy subjects were recruited for four focus groups in each of two sites divided by ostomy type (colostomy versus ileostomy) and overall mCOH-QOL-Ostomy HR-QOL score (highest versus lowest quartile). The focus groups further evaluated barriers, concerns, and adaptation methods and skills. This report presents recruitment results, reliability of survey instruments, and demographic characteristics of the sample. The overall response (i.e., recruitment) rate across all sites was 48% and by site was 53%, 57%, and 37%, respectively (p ostomies had significantly longer time since surgery than controls (p ostomies is an illustration of a successful mixed methods approach to HR-QOL research. We collected meaningful quantitative and qualitative data that will be used in the development of new approaches to care that will lead to improved functioning and well-being in persons living with ostomies. Subsequent reports will provide the results of this research project.

  6. Validation of single-sample doubly labeled water method

    International Nuclear Information System (INIS)

    Webster, M.D.; Weathers, W.W.

    1989-01-01

    We have experimentally validated a single-sample variant of the doubly labeled water method for measuring metabolic rate and water turnover in a very small passerine bird, the verdin (Auriparus flaviceps). We measured CO 2 production using the Haldane gravimetric technique and compared these values with estimates derived from isotopic data. Doubly labeled water results based on the one-sample calculations differed from Haldane values by less than 0.5% on average (range -8.3 to 11.2%, n = 9). Water flux computed by the single-sample method differed by -1.5% on average from results for the same birds based on the standard, two-sample technique (range -13.7 to 2.0%, n = 9)

  7. The cosmological analysis of X-ray cluster surveys - I. A new method for interpreting number counts

    Science.gov (United States)

    Clerc, N.; Pierre, M.; Pacaud, F.; Sadibekova, T.

    2012-07-01

    We present a new method aimed at simplifying the cosmological analysis of X-ray cluster surveys. It is based on purely instrumental observable quantities considered in a two-dimensional X-ray colour-magnitude diagram (hardness ratio versus count rate). The basic principle is that even in rather shallow surveys, substantial information on cluster redshift and temperature is present in the raw X-ray data and can be statistically extracted; in parallel, such diagrams can be readily predicted from an ab initio cosmological modelling. We illustrate the methodology for the case of a 100-deg2XMM survey having a sensitivity of ˜10-14 erg s-1 cm-2 and fit at the same time, the survey selection function, the cluster evolutionary scaling relations and the cosmology; our sole assumption - driven by the limited size of the sample considered in the case study - is that the local cluster scaling relations are known. We devote special attention to the realistic modelling of the count-rate measurement uncertainties and evaluate the potential of the method via a Fisher analysis. In the absence of individual cluster redshifts, the count rate and hardness ratio (CR-HR) method appears to be much more efficient than the traditional approach based on cluster counts (i.e. dn/dz, requiring redshifts). In the case where redshifts are available, our method performs similar to the traditional mass function (dn/dM/dz) for the purely cosmological parameters, but constrains better parameters defining the cluster scaling relations and their evolution. A further practical advantage of the CR-HR method is its simplicity: this fully top-down approach totally bypasses the tedious steps consisting in deriving cluster masses from X-ray temperature measurements.

  8. Sampling efficiency for species composition assessments using the ...

    African Journals Online (AJOL)

    A pilot survey to determine the sampling efficiency of the wheel-point method, using the nearest plant method, to assess species composition (using replicate similarity related to sampling intensity, and total sampling time) was conducted on three plot sizes (20 x 20m, 30 x 30m, 40 x 40m) at two sites in a semi-arid savanna.

  9. Nationwide survey of policies and practices related to capillary blood sampling in medical laboratories in Croatia.

    Science.gov (United States)

    Krleza, Jasna Lenicek

    2014-01-01

    Capillary sampling is increasingly used to obtain blood for laboratory tests in volumes as small as necessary and as non-invasively as possible. Whether capillary blood sampling is also frequent in Croatia, and whether it is performed according to international laboratory standards is unclear. All medical laboratories that participate in the Croatian National External Quality Assessment Program (N = 204) were surveyed on-line to collect information about the laboratory's parent institution, patient population, types and frequencies of laboratory tests based on capillary blood samples, choice of reference intervals, and policies and procedures specifically related to capillary sampling. Sampling practices were compared with guidelines from the Clinical and Laboratory Standards Institute (CLSI) and the World Health Organization (WHO). Of the 204 laboratories surveyed, 174 (85%) responded with complete questionnaires. Among the 174 respondents, 155 (89%) reported that they routinely perform capillary sampling, which is carried out by laboratory staff in 118 laboratories (76%). Nearly half of respondent laboratories (48%) do not have a written protocol including order of draw for multiple sampling. A single puncture site is used to provide capillary blood for up to two samples at 43% of laboratories that occasionally or regularly perform such sampling. Most respondents (88%) never perform arterialisation prior to capillary blood sampling. Capillary blood sampling is highly prevalent in Croatia across different types of clinical facilities and patient populations. Capillary sampling procedures are not standardised in the country, and the rate of laboratory compliance with CLSI and WHO guidelines is low.

  10. The Italian national survey on radon indoors run by several different regional laboratories: Sampling strategy, realization and follow-up

    International Nuclear Information System (INIS)

    Bochicchio, F.; Risica, S.; Piermattei, S.

    1993-01-01

    The paper outlines the criteria and organization adopted by the Italian National Institutions in carrying out a representative national survey to evaluate the distribution of radon concentration and the exposure of the Italian population to natural radiation indoors. The main items of the survey - i.e. sampling design, choice of the sample size (5000 dwellings), organization, analysis of the actual sample structure, questionnaire to collect data about families and their dwellings, experimental set up and communication with the public - are discussed. Some results, concerning a first fraction of the total sample, are also presented. (author). 13 refs, 2 figs, 2 tabs

  11. U.S. Geological Survey laboratory method for methyl tert-Butyl ether and other fuel oxygenates

    Science.gov (United States)

    Raese, Jon W.; Rose, Donna L.; Sandstrom, Mark W.

    1995-01-01

    Methyl tert-butyl ether (MTBE) was found in shallow ground-water samples in a study of 8 urban and 20 agricultural areas throughout the United States in 1993 and 1994 (Squillace and others, 1995, p. 1). The compound is added to gasoline either seasonally or year round in many parts of the United States to increase the octane level and to reduce carbon monoxide and ozone levels in the air. The U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL), near Denver, uses state-of-the-art technology to analyze samples for MTBE as part of the USGS water-quality studies. In addition, the NWQL offers custom analyses to determine two other fuel oxygenates--ethyl tert-butyl ether (ETBE) and tert-amyl methyl ether (TAME). The NWQL was not able to obtain a reference standard for tert-amyl ethyl ether (TAEE), another possible fuel oxygenate (Shelley and Fouhy, 1994, p. 63). The shallow ground-water samples were collected as part of the USGS National Water-Quality Assessment Program. These samples were collected from 211 urban wells or springs and 562 agricultural wells sampled by the USGS in 1993 and 1994. The wells were keyed to specific land-use areas to assess the effects of different uses on ground-water quality (Squillace and others, 1995, p. 2). Ground-water samples were preserved on site to pH less than or equal to 2 with a solution of 1:1 hydrochloric acid. All samples were analyzed at the NWQL within 2 weeks after collection. The purpose of this fact sheet is to explain briefly the analytical method implemented by the USGS for determining MTBE and other fuel oxygenates. The scope is necessarily limited to an overview of the analytical method (instrumentation, sample preparation, calibration and quantitation, identification, and preservation of samples) and method performance (reagent blanks, accuracy, and precision).

  12. Analysis and radiological assessment of survey results and samples from the beaches around Sellafield

    International Nuclear Information System (INIS)

    Webb, G.A.M.; Fry, F.A.

    1983-12-01

    After radioactive sea debris had been found on beaches near the BNFL, Sellafield, plant, NRPB was asked by the Department of the Environment to analyse some of the samples collected and to assess the radiological hazard to members of the public. A report is presented containing an analysis of survey reports for the period 19 November - 4 December 1983 and preliminary results of the analysis of all samples received, together with the Board's recommendations. (author)

  13. Comparing two survey methods for estimating maternal and perinatal mortality in rural Cambodia.

    Science.gov (United States)

    Chandy, Hoeuy; Heng, Yang Van; Samol, Ha; Husum, Hans

    2008-03-01

    We need solid estimates of maternal mortality rates (MMR) to monitor the impact of maternal care programs. Cambodian health authorities and WHO report the MMR in Cambodia at 450 per 100,000 live births. The figure is drawn from surveys where information is obtained by interviewing respondents about the survival of all their adult sisters (sisterhood method). The estimate is statistically imprecise, 95% confidence intervals ranging from 260 to 620/100,000. The MMR estimate is also uncertain due to under-reporting; where 80-90% of women deliver at home maternal fatalities may go undetected especially where mortality is highest, in remote rural areas. The aim of this study was to attain more reliable MMR estimates by using survey methods other than the sisterhood method prior to an intervention targeting obstetric rural emergencies. The study was carried out in rural Northwestern Cambodia where access to health services is poor and poverty, endemic diseases, and land mines are endemic. Two survey methods were applied in two separate sectors: a community-based survey gathering data from public sources and a household survey gathering data direct from primary sources. There was no statistically significant difference between the two survey results for maternal deaths, both types of survey reported mortality rates around the public figure. The household survey reported a significantly higher perinatal mortality rate as compared to the community-based survey, 8.6% versus 5.0%. Also the household survey gave qualitative data important for a better understanding of the many problems faced by mothers giving birth in the remote villages. There are detection failures in both surveys; the failure rate may be as high as 30-40%. PRINCIPLE CONCLUSION: Both survey methods are inaccurate, therefore inappropriate for evaluation of short-term changes of mortality rates. Surveys based on primary informants yield qualitative information about mothers' hardships important for the design

  14. Detection of enterotoxigenic Clostridium perfringens in meat samples by using molecular methods.

    Science.gov (United States)

    Kaneko, Ikuko; Miyamoto, Kazuaki; Mimura, Kanako; Yumine, Natsuko; Utsunomiya, Hirotoshi; Akimoto, Shigeru; McClane, Bruce A

    2011-11-01

    To prevent food-borne bacterial diseases and to trace bacterial contamination events to foods, microbial source tracking (MST) methods provide important epidemiological information. To apply molecular methods to MST, it is necessary not only to amplify bacterial cells to detection limit levels but also to prepare DNA with reduced inhibitory compounds and contamination. Isolates carrying the Clostridium perfringens enterotoxin gene (cpe) on the chromosome or a plasmid rank among the most important food-borne pathogens. Previous surveys indicated that cpe-positive C. perfringens isolates are present in only ∼5% of nonoutbreak food samples and then only at low numbers, usually less than 3 cells/g. In this study, four molecular assays for the detection of cpe-positive C. perfringens isolates, i.e., ordinary PCR, nested PCR, real-time PCR, and loop-mediated isothermal amplification (LAMP), were developed and evaluated for their reliability using purified DNA. For use in the artificial contamination of meat samples, DNA templates were prepared by three different commercial DNA preparation kits. The four molecular assays always detected cpe when >10³ cells/g of cpe-positive C. perfringens were present, using any kit. Of three tested commercial DNA preparation kits, the InstaGene matrix kit appeared to be most suitable for the testing of a large number of samples. By using the InstaGene matrix kit, the four molecular assays efficiently detected cpe using DNA prepared from enrichment culture specimens of meat samples contaminated with low numbers of cpe-positive C. perfringens vegetative cells or spores. Overall, the current study developed molecular assay protocols for MST to detect the contamination of foods with low numbers of cells, and at a low frequency, of cpe-positive C. perfringens isolates.

  15. Detecting Renibacterium salmoninarum in wild brown trout by use of multiple organ samples and diagnostic methods

    Science.gov (United States)

    Guomundsdottir, S.; Applegate, Lynn M.; Arnason, I.O.; Kristmundsson, A.; Purcell, Maureen K.; Elliott, Diane G.

    2017-01-01

    Renibacterium salmoninarum, the causative agent of salmonid bacterial kidney disease (BKD), is endemic in many wild trout species in northerly regions. The aim of the present study was to determine the optimal R. salmoninarum sampling/testing strategy for wild brown trout (Salmo trutta L.) populations in Iceland. Fish were netted in a lake and multiple organs—kidney, spleen, gills, oesophagus and mid-gut—were sampled and subjected to five detection tests i.e. culture, polyclonal enzyme-linked immunosorbent assay (pELISA) and three different PCR tests. The results showed that each fish had encountered R. salmoninarum but there were marked differences between results obtained depending on organ and test. The bacterium was not cultured from any kidney sample while all kidney samples were positive by pELISA. At least one organ from 92.9% of the fish tested positive by PCR. The results demonstrated that the choice of tissue and diagnostic method can dramatically influence the outcome of R. salmoninarum surveys.

  16. Standard methods for sampling North American freshwater fishes

    Science.gov (United States)

    Bonar, Scott A.; Hubert, Wayne A.; Willis, David W.

    2009-01-01

    This important reference book provides standard sampling methods recommended by the American Fisheries Society for assessing and monitoring freshwater fish populations in North America. Methods apply to ponds, reservoirs, natural lakes, and streams and rivers containing cold and warmwater fishes. Range-wide and eco-regional averages for indices of abundance, population structure, and condition for individual species are supplied to facilitate comparisons of standard data among populations. Provides information on converting nonstandard to standard data, statistical and database procedures for analyzing and storing standard data, and methods to prevent transfer of invasive species while sampling.

  17. Evaluation of methods to calibrate radiation survey meters

    International Nuclear Information System (INIS)

    Robinson, R.C.; Arbeau, N.D.

    1987-04-01

    Calibration requirements for radiation survey meters used in industrial radiography have been reviewed. Information obtained from a literature search, discussions with CSLD inspectors and firms performing calibrations has been considered. Based on this review a set of minimum calibration requirements was generated which, when met, will determine that the survey meter is suited for measurements described in the current AEC Regulations that apply to industrial radiography equipment. These requirements are presented in this report and may be used as guidelines for evaluating calibration methods proposed or in use in industry. 39 refs

  18. The "Tracked Roaming Transect" and distance sampling methods increase the efficiency of underwater visual censuses.

    Directory of Open Access Journals (Sweden)

    Alejo J Irigoyen

    Full Text Available Underwater visual census (UVC is the most common approach for estimating diversity, abundance and size of reef fishes in shallow and clear waters. Abundance estimation through UVC is particularly problematic in species occurring at low densities and/or highly aggregated because of their high variability at both spatial and temporal scales. The statistical power of experiments involving UVC techniques may be increased by augmenting the number of replicates or the area surveyed. In this work we present and test the efficiency of an UVC method based on diver towed GPS, the Tracked Roaming Transect (TRT, designed to maximize transect length (and thus the surveyed area with respect to diving time invested in monitoring, as compared to Conventional Strip Transects (CST. Additionally, we analyze the effect of increasing transect width and length on the precision of density estimates by comparing TRT vs. CST methods using different fixed widths of 6 and 20 m (FW3 and FW10, respectively and the Distance Sampling (DS method, in which perpendicular distance of each fish or group of fishes to the transect line is estimated by divers up to 20 m from the transect line. The TRT was 74% more time and cost efficient than the CST (all transect widths considered together and, for a given time, the use of TRT and/or increasing the transect width increased the precision of density estimates. In addition, since with the DS method distances of fishes to the transect line have to be estimated, and not measured directly as in terrestrial environments, errors in estimations of perpendicular distances can seriously affect DS density estimations. To assess the occurrence of distance estimation errors and their dependence on the observer's experience, a field experiment using wooden fish models was performed. We tested the precision and accuracy of density estimators based on fixed widths and the DS method. The accuracy of the estimates was measured comparing the actual

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

    Directory of Open Access Journals (Sweden)

    Romain Guignard

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

  20. The Swift Gamma-Ray Burst Host Galaxy Legacy Survey. I. Sample Selection and Redshift Distribution

    Science.gov (United States)

    Perley, D. A.; Kruhler, T.; Schulze, S.; Postigo, A. De Ugarte; Hjorth, J.; Berger, E.; Cenko, S. B.; Chary, R.; Cucchiara, A.; Ellis, R.; hide

    2016-01-01

    We introduce the Swift Gamma-Ray Burst Host Galaxy Legacy Survey (SHOALS), a multi-observatory high redshift galaxy survey targeting the largest unbiased sample of long-duration gamma-ray burst (GRB) hosts yet assembled (119 in total). We describe the motivations of the survey and the development of our selection criteria, including an assessment of the impact of various observability metrics on the success rate of afterglow-based redshift measurement. We briefly outline our host galaxy observational program, consisting of deep Spitzer/IRAC imaging of every field supplemented by similarly deep, multicolor optical/near-IR photometry, plus spectroscopy of events without preexisting redshifts. Our optimized selection cuts combined with host galaxy follow-up have so far enabled redshift measurements for 110 targets (92%) and placed upper limits on all but one of the remainder. About 20% of GRBs in the sample are heavily dust obscured, and at most 2% originate from z > 5.5. Using this sample, we estimate the redshift-dependent GRB rate density, showing it to peak at z approx. 2.5 and fall by at least an order of magnitude toward low (z = 0) redshift, while declining more gradually toward high (z approx. 7) redshift. This behavior is consistent with a progenitor whose formation efficiency varies modestly over cosmic history. Our survey will permit the most detailed examination to date of the connection between the GRB host population and general star-forming galaxies, directly measure evolution in the host population over cosmic time and discern its causes, and provide new constraints on the fraction of cosmic star formation occurring in undetectable galaxies at all redshifts.

  1. Passive sampling methods for contaminated sediments

    DEFF Research Database (Denmark)

    Peijnenburg, Willie J.G.M.; Teasdale, Peter R.; Reible, Danny

    2014-01-01

    “Dissolved” concentrations of contaminants in sediment porewater (Cfree) provide a more relevant exposure metric for risk assessment than do total concentrations. Passive sampling methods (PSMs) for estimating Cfree offer the potential for cost-efficient and accurate in situ characterization...

  2. Field evaluation of personal sampling methods for multiple bioaerosols.

    Science.gov (United States)

    Wang, Chi-Hsun; Chen, Bean T; Han, Bor-Cheng; Liu, Andrew Chi-Yeu; Hung, Po-Chen; Chen, Chih-Yong; Chao, Hsing Jasmine

    2015-01-01

    Ambient bioaerosols are ubiquitous in the daily environment and can affect health in various ways. However, few studies have been conducted to comprehensively evaluate personal bioaerosol exposure in occupational and indoor environments because of the complex composition of bioaerosols and the lack of standardized sampling/analysis methods. We conducted a study to determine the most efficient collection/analysis method for the personal exposure assessment of multiple bioaerosols. The sampling efficiencies of three filters and four samplers were compared. According to our results, polycarbonate (PC) filters had the highest relative efficiency, particularly for bacteria. Side-by-side sampling was conducted to evaluate the three filter samplers (with PC filters) and the NIOSH Personal Bioaerosol Cyclone Sampler. According to the results, the Button Aerosol Sampler and the IOM Inhalable Dust Sampler had the highest relative efficiencies for fungi and bacteria, followed by the NIOSH sampler. Personal sampling was performed in a pig farm to assess occupational bioaerosol exposure and to evaluate the sampling/analysis methods. The Button and IOM samplers yielded a similar performance for personal bioaerosol sampling at the pig farm. However, the Button sampler is more likely to be clogged at high airborne dust concentrations because of its higher flow rate (4 L/min). Therefore, the IOM sampler is a more appropriate choice for performing personal sampling in environments with high dust levels. In summary, the Button and IOM samplers with PC filters are efficient sampling/analysis methods for the personal exposure assessment of multiple bioaerosols.

  3. Geochemical reanalysis of historical U.S. Geological Survey sediment samples from the Zane Hills, Hughes and Shungnak quadrangles, Alaska

    Science.gov (United States)

    Werdon, Melanie B.; Granitto, Matthew; Azain, Jaime S.

    2015-01-01

    The State of Alaska’s Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska’s statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. As part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential.The USGS is also undertaking SCM-related geologic studies in Alaska through the federally funded Alaska Critical Minerals cooperative project. DGGS and USGS share the goal of evaluating Alaska’s strategic and critical minerals potential and together created a Letter of Agreement (signed December 2012) and a supplementary Technical Assistance Agreement (#14CMTAA143458) to facilitate the two agencies’ cooperative work. Under these agreements, DGGS contracted the USGS in Denver to reanalyze historical USGS sediment samples from Alaska.For this report, DGGS funded reanalysis of 105 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from the Zane Hills area in the Hughes and Shungnak quadrangles, Alaska (fig. 1). The USGS was responsible for sample retrieval from the National Geochemical Sample Archive (NGSA) in Denver, Colorado through the final quality assurance/quality control (QA/QC) of the geochemical analyses obtained through the USGS contract lab. The new geochemical data are published in this report as a coauthored DGGS report, and will be incorporated into the statewide geochemical databases of both agencies.

  4. [Sampling methods for PM2.5 from stationary sources: a review].

    Science.gov (United States)

    Jiang, Jing-Kun; Deng, Jian-Guo; Li, Zhen; Li, Xing-Hua; Duan, Lei; Hao, Ji-Ming

    2014-05-01

    The new China national ambient air quality standard has been published in 2012 and will be implemented in 2016. To meet the requirements in this new standard, monitoring and controlling PM2,,5 emission from stationary sources are very important. However, so far there is no national standard method on sampling PM2.5 from stationary sources. Different sampling methods for PM2.5 from stationary sources and relevant international standards were reviewed in this study. It includes the methods for PM2.5 sampling in flue gas and the methods for PM2.5 sampling after dilution. Both advantages and disadvantages of these sampling methods were discussed. For environmental management, the method for PM2.5 sampling in flue gas such as impactor and virtual impactor was suggested as a standard to determine filterable PM2.5. To evaluate environmental and health effects of PM2.5 from stationary sources, standard dilution method for sampling of total PM2.5 should be established.

  5. The Canadian Human Activity Pattern Survey: report of methods and population surveyed.

    Science.gov (United States)

    Leech, J A; Wilby, K; McMullen, E; Laporte, K

    1996-01-01

    The assessment of health risk due to environmental contaminants depends upon accurate estimates of the distribution of population exposures. Exposure assessment, in turn, requires information on the time people spend in micro-environments and their activities during periods of exposure. This paper describes preliminary results including study methodology and population sampled in a large Canadian survey of time-activity patterns. A 24-hour diary recall survey was performed in 2381 households (representing a 65% response rate) to describe in detail the timing, location and activity pattern of one household member (the adult or child with the next birthday). Four cities (Toronto, Vancouver, Edmonton and Saint John, NB) and their suburbs were sampled by random-digit dialling over a nine-month period in 1994/1995. Supplemental questionnaires inquiring about sociodemographic information, house and household characteristics and potential exposure to toxins in the air and water were also administered. In general, the results show that respondents spend the majority of their time indoors (88.6%) with smaller proportions of time outdoors (6.1%) and in vehicles (5.3%). Children under the age of 12 spend more time both indoors and outdoors and less time in transit than do adults. The data from this study will be used to define more accurately the exposure of Canadians to a variety of toxins in exposure assessment models and to improve upon the accuracy of risk assessment for a variety of acute and chronic health effects known or suspected to be related to environmental exposures.

  6. Statistical sampling strategies for survey of soil contamination

    NARCIS (Netherlands)

    Brus, D.J.

    2011-01-01

    This chapter reviews methods for selecting sampling locations in contaminated soils for three situations. In the first situation a global estimate of the soil contamination in an area is required. The result of the surey is a number or a series of numbers per contaminant, e.g. the estimated mean

  7. Unemployment estimation: Spatial point referenced methods and models

    KAUST Repository

    Pereira, Soraia

    2017-06-26

    Portuguese Labor force survey, from 4th quarter of 2014 onwards, started geo-referencing the sampling units, namely the dwellings in which the surveys are carried. This opens new possibilities in analysing and estimating unemployment and its spatial distribution across any region. The labor force survey choose, according to an preestablished sampling criteria, a certain number of dwellings across the nation and survey the number of unemployed in these dwellings. Based on this survey, the National Statistical Institute of Portugal presently uses direct estimation methods to estimate the national unemployment figures. Recently, there has been increased interest in estimating these figures in smaller areas. Direct estimation methods, due to reduced sampling sizes in small areas, tend to produce fairly large sampling variations therefore model based methods, which tend to

  8. Approximation of the exponential integral (well function) using sampling methods

    Science.gov (United States)

    Baalousha, Husam Musa

    2015-04-01

    Exponential integral (also known as well function) is often used in hydrogeology to solve Theis and Hantush equations. Many methods have been developed to approximate the exponential integral. Most of these methods are based on numerical approximations and are valid for a certain range of the argument value. This paper presents a new approach to approximate the exponential integral. The new approach is based on sampling methods. Three different sampling methods; Latin Hypercube Sampling (LHS), Orthogonal Array (OA), and Orthogonal Array-based Latin Hypercube (OA-LH) have been used to approximate the function. Different argument values, covering a wide range, have been used. The results of sampling methods were compared with results obtained by Mathematica software, which was used as a benchmark. All three sampling methods converge to the result obtained by Mathematica, at different rates. It was found that the orthogonal array (OA) method has the fastest convergence rate compared with LHS and OA-LH. The root mean square error RMSE of OA was in the order of 1E-08. This method can be used with any argument value, and can be used to solve other integrals in hydrogeology such as the leaky aquifer integral.

  9. 40 CFR 80.8 - Sampling methods for gasoline and diesel fuel.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 16 2010-07-01 2010-07-01 false Sampling methods for gasoline and... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES General Provisions § 80.8 Sampling methods for gasoline and diesel fuel. The sampling methods specified in this section shall be used to collect samples...

  10. Consistently low prevalence of syphilis among female sex workers in Jinan, China: findings from two consecutive respondent driven sampling surveys.

    Directory of Open Access Journals (Sweden)

    Meizhen Liao

    Full Text Available BACKGROUND: Routine surveillance using convenient sampling found low prevalence of HIV and syphilis among female sex workers in China. Two consecutive surveys using respondent driven sampling were conducted in 2008 and 2009 to examine the prevalence of HIV and syphilis among female sex workers in Jinan, China. METHODS: A face-to-face interview was conducted to collect demographic, behavioral and service utilization information using a structured questionnaire. Blood samples were drawn for serological tests of HIV-1 antibody and syphilis antibody. Respondent Driven Sampling Analysis Tool was used to generate population level estimates. RESULTS: In 2008 and in 2009, 363 and 432 subjects were recruited and surveyed respectively. Prevalence of syphilis was 2.8% in 2008 and 2.2% in 2009, while no HIV case was found in both years. Results are comparable to those from routine sentinel surveillance system in the city. Only 60.8% subjects in 2008 and 48.3% in 2009 reported a consistent condom use with clients during the past month. Over 50% subjects had not been covered by any HIV-related services in the past year, with only 15.6% subjects in 2008 and 13.1% in 2009 ever tested for HIV. CONCLUSIONS: Despite the low prevalence of syphilis and HIV, risk behaviors are common. Targeted interventions to promote the safe sex and utilization of existing intervention services are still needed to keep the epidemic from growing.

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

    International Nuclear Information System (INIS)

    Wang Ruihong; Ji Zhicheng; Pei Lucheng

    2012-01-01

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

  12. Demonstration Exercise of a Validated Sample Collection Method for Powders Suspected of Being Biological Agents in Georgia 2006

    International Nuclear Information System (INIS)

    Marsh, B.

    2007-01-01

    August 7, 2006 the state of Georgia conducted a collaborative sampling exercise between the Georgia National Guard 4th Civil Support Team Weapons of Mass Destruction (CST-WMD) and the Georgia Department of Human Resources Division of Public Health demonstrating a recently validated bulk powder sampling method. The exercise was hosted at the Federal Law Enforcement Training Center (FLETC) at Glynn County, Georgia and involved the participation of the Georgia Emergency Management Agency (GEMA), Georgia National Guard, Georgia Public Health Laboratories, the Federal Bureau of Investigation Atlanta Office, Georgia Coastal Health District, and the Glynn County Fire Department. The purpose of the exercise was to demonstrate a recently validated national sampling standard developed by the American Standards and Test Measures (ASTM) International; ASTM E2458 S tandard Practice for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biological Agents from Nonporous Surfaces . The intent of the exercise was not to endorse the sampling method, but to develop a model for exercising new sampling methods in the context of existing standard operating procedures (SOPs) while strengthening operational relationships between response teams and analytical laboratories. The exercise required a sampling team to respond real-time to an incident cross state involving a clandestine bio-terrorism production lab found within a recreational vehicle (RV). Sample targets consisted of non-viable gamma irradiated B. anthracis Sterne spores prepared by Dugway Proving Ground. Various spore concentration levels were collected by the ASTM method, followed by on- and off-scene analysis utilizing the Center for Disease Control (CDC) Laboratory Response Network (LRN) and National Guard Bureau (NGB) CST mobile Analytical Laboratory Suite (ALS) protocols. Analytical results were compared and detailed surveys of participant evaluation comments were examined. I will

  13. Underwater sediment-contact radiation survey method

    International Nuclear Information System (INIS)

    Lee, D.R.; St. Aubin, M.; Welch, S.J.

    1991-01-01

    The authors are striving to produce a practical system for mapping lateral distributions in gamma activity on submerged sediments. This is in response to the need for quality control and interpretation of data obtainable by sediment sampling and analyses near nuclear utilities. A prototype gamma probe has been constructed and tested. The prototype is essentially a background survey meter packaged in a 53-cm-long x 5.4-cm-diam waterproof vehicle. This usage-shaped vehicle is connected to a cable for towing in contact with bottom sediments of lakes, rivers, and coastal waters. This vehicle, or sediment probe as it is called, was initially developed for measuring sediment electrical conductances, a parameter that can be used to locate underwater areas of groundwater and contaminant upwelling. During towing, the probe does not roll or twist around its longitudinal axis by more than 10 deg, so that sensors, which have been fixed within the vehicle, can be oriented to look up, down, or sideways. In over 450 lin-km of underwater survey, only a single sediment probe has been irretrievably snagged on sunken rocks or other debris. Work in the Ottawa River near the Chalk River Laboratories has shown good agreement among point measurements of river sediment with continuous measurements using the moving probe

  14. The IMACS Cluster Building Survey. I. Description of the Survey and Analysis Methods

    Science.gov (United States)

    Oemler Jr., Augustus; Dressler, Alan; Gladders, Michael G.; Rigby, Jane R.; Bai, Lei; Kelson, Daniel; Villanueva, Edward; Fritz, Jacopo; Rieke, George; Poggianti, Bianca M.; hide

    2013-01-01

    The IMACS Cluster Building Survey uses the wide field spectroscopic capabilities of the IMACS spectrograph on the 6.5 m Baade Telescope to survey the large-scale environment surrounding rich intermediate-redshift clusters of galaxies. The goal is to understand the processes which may be transforming star-forming field galaxies into quiescent cluster members as groups and individual galaxies fall into the cluster from the surrounding supercluster. This first paper describes the survey: the data taking and reduction methods. We provide new calibrations of star formation rates (SFRs) derived from optical and infrared spectroscopy and photometry. We demonstrate that there is a tight relation between the observed SFR per unit B luminosity, and the ratio of the extinctions of the stellar continuum and the optical emission lines.With this, we can obtain accurate extinction-corrected colors of galaxies. Using these colors as well as other spectral measures, we determine new criteria for the existence of ongoing and recent starbursts in galaxies.

  15. THE IMACS CLUSTER BUILDING SURVEY. I. DESCRIPTION OF THE SURVEY AND ANALYSIS METHODS

    Energy Technology Data Exchange (ETDEWEB)

    Oemler, Augustus Jr.; Dressler, Alan; Kelson, Daniel; Villanueva, Edward [Observatories of the Carnegie Institution for Science, 813 Santa Barbara St., Pasadena, CA 91101-1292 (United States); Gladders, Michael G. [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States); Rigby, Jane R. [Observational Cosmology Lab, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Bai Lei [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Fritz, Jacopo [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Rieke, George [Steward Observatory, University of Arizona, Tucson, AZ 8572 (United States); Poggianti, Bianca M.; Vulcani, Benedetta, E-mail: oemler@obs.carnegiescience.edu [INAF-Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy)

    2013-06-10

    The IMACS Cluster Building Survey uses the wide field spectroscopic capabilities of the IMACS spectrograph on the 6.5 m Baade Telescope to survey the large-scale environment surrounding rich intermediate-redshift clusters of galaxies. The goal is to understand the processes which may be transforming star-forming field galaxies into quiescent cluster members as groups and individual galaxies fall into the cluster from the surrounding supercluster. This first paper describes the survey: the data taking and reduction methods. We provide new calibrations of star formation rates (SFRs) derived from optical and infrared spectroscopy and photometry. We demonstrate that there is a tight relation between the observed SFR per unit B luminosity, and the ratio of the extinctions of the stellar continuum and the optical emission lines. With this, we can obtain accurate extinction-corrected colors of galaxies. Using these colors as well as other spectral measures, we determine new criteria for the existence of ongoing and recent starbursts in galaxies.

  16. Field evaluation of personal sampling methods for multiple bioaerosols.

    Directory of Open Access Journals (Sweden)

    Chi-Hsun Wang

    Full Text Available Ambient bioaerosols are ubiquitous in the daily environment and can affect health in various ways. However, few studies have been conducted to comprehensively evaluate personal bioaerosol exposure in occupational and indoor environments because of the complex composition of bioaerosols and the lack of standardized sampling/analysis methods. We conducted a study to determine the most efficient collection/analysis method for the personal exposure assessment of multiple bioaerosols. The sampling efficiencies of three filters and four samplers were compared. According to our results, polycarbonate (PC filters had the highest relative efficiency, particularly for bacteria. Side-by-side sampling was conducted to evaluate the three filter samplers (with PC filters and the NIOSH Personal Bioaerosol Cyclone Sampler. According to the results, the Button Aerosol Sampler and the IOM Inhalable Dust Sampler had the highest relative efficiencies for fungi and bacteria, followed by the NIOSH sampler. Personal sampling was performed in a pig farm to assess occupational bioaerosol exposure and to evaluate the sampling/analysis methods. The Button and IOM samplers yielded a similar performance for personal bioaerosol sampling at the pig farm. However, the Button sampler is more likely to be clogged at high airborne dust concentrations because of its higher flow rate (4 L/min. Therefore, the IOM sampler is a more appropriate choice for performing personal sampling in environments with high dust levels. In summary, the Button and IOM samplers with PC filters are efficient sampling/analysis methods for the personal exposure assessment of multiple bioaerosols.

  17. Enantioselective analysis of chloramphenicol residues in honey samples by chiral LC-MS/MS and results of a honey survey.

    Science.gov (United States)

    Rimkus, Gerhard G; Hoffmann, Dirk

    2017-06-01

    Chloramphenicol (CAP) is a broad-spectrum antibiotic used widely in both human and veterinary medication. Since 1994, CAP has not been authorised for use in food-producing animals in the European Union due to several adverse effects. A minimum required performance level (MRPL) of 0.3 µg kg - 1 was established in 2003. The CAP molecule contains two asymmetric centres, thus in total four para-CAP stereoisomers exist. Only the RR-CAP enantiomer is bioactive, having significant antimicrobial activity. For the first time a chiral LC-MS/MS method is reported to identify and quantify the four CAP enantiomers at residue levels in honey samples. The method was validated at two concentration levels. The decision limits (CCα) and detection capabilities (CCß) were well below 0.3 µg kg - 1 , with limits of quantification (LOQs) between 0.08 and 0.12 µg kg - 1 for all four enantiomers. The method provides a sensitive and reliable analysis of CAP enantiomers in honey, and proved its robustness during the daily routine analyses of numerous honey samples. In an internal honey survey, in total 40 honey samples from different geographical regions with identified CAP residues at or above the MRPL were reanalysed by chiral LC-MS/MS. In nine honey samples only the bioactive RR-CAP was detected as anticipated. However, in all other 31 honey samples the non-bioactive SS-CAP was also identified and quantified unambiguously. In 10 of these samples, mixtures of RR- and SS-CAP were analysed, and in 21 samples only the SS-CAP enantiomer, with concentrations up to 2.2 µg kg - 1 . Most of these samples are honeys from Ukraine and Eastern Europe. This is the first report of SS-CAP residues in food samples. The potential sources for these findings are discussed and the need of further systematic studies emphasised. It is recommended to examine in more depth the toxicological profile of the individual CAP stereoisomers.

  18. Sample preparation method for ICP-MS measurement of 99Tc in a large amount of environmental samples

    International Nuclear Information System (INIS)

    Kondo, M.; Seki, R.

    2002-01-01

    Sample preparation for measurement of 99 Tc in a large amount of soil and water samples by ICP-MS has been developed using 95m Tc as a yield tracer. This method is based on the conventional method for a small amount of soil samples using incineration, acid digestion, extraction chromatography (TEVA resin) and ICP-MS measurement. Preliminary concentration of Tc has been introduced by co-precipitation with ferric oxide. The matrix materials in a large amount of samples were more sufficiently removed with keeping the high recovery of Tc than previous method. The recovery of Tc was 70-80% for 100 g soil samples and 60-70% for 500 g of soil and 500 L of water samples. The detection limit of this method was evaluated as 0.054 mBq/kg in 500 g soil and 0.032 μBq/L in 500 L water. The determined value of 99 Tc in the IAEA-375 (soil sample collected near the Chernobyl Nuclear Reactor) was 0.25 ± 0.02 Bq/kg. (author)

  19. Systems and methods for self-synchronized digital sampling

    Science.gov (United States)

    Samson, Jr., John R. (Inventor)

    2008-01-01

    Systems and methods for self-synchronized data sampling are provided. In one embodiment, a system for capturing synchronous data samples is provided. The system includes an analog to digital converter adapted to capture signals from one or more sensors and convert the signals into a stream of digital data samples at a sampling frequency determined by a sampling control signal; and a synchronizer coupled to the analog to digital converter and adapted to receive a rotational frequency signal from a rotating machine, wherein the synchronizer is further adapted to generate the sampling control signal, and wherein the sampling control signal is based on the rotational frequency signal.

  20. Practical methods for radiation survey in nuclear installations

    International Nuclear Information System (INIS)

    Shweikani, R.

    2001-12-01

    This study is placed to those who are responsible to perform radiation survey in the nuclear installations, especially the beginners. Therefore, it gives a comprehensive view to all-important aspects related to their work starting from the structure of atoms to the practical steps for radiation survey works. So, it clarify how to perform personal monitoring, methods for monitoring surface contamination, methods for measuring radioactivity of gases and radioactive aerosols in air, monitoring radiation doses, measuring radiation influences in workplaces and finally measuring internal exposure of radiation workers in nuclear installations. Finally, The study shows some cases of breaches of radiation protection rules in some American nuclear installations and describes the final results of these breaches. The aim of this is to assure that any breach or ignore to radiation protection principles may produce bad results, and there is no leniency in implementing environmental radiation protection principles. (author)

  1. International survey of methods used in health technology assessment (HTA: does practice meet the principles proposed for good research?

    Directory of Open Access Journals (Sweden)

    Stephens JM

    2012-08-01

    , and data availability for emerging technologies.Conclusion: This is the first international survey to specifically assess the state of HTA research methods. Future efforts should expand the respondent sample to include more emerging markets and update the results of this survey to specifically address additional aspects of research methods in HTA.Keywords: survey, technology assessment, payers, research methods, reimbursement

  2. Virus isolation vs RT-PCR: which method is more successful in detecting VHSV and IHNV in fish tissue sampled under field conditions?

    DEFF Research Database (Denmark)

    Knüsel, R.; Bergmann, S. M.; Einer-Jensen, Katja

    2007-01-01

    in Switzerland. Compared to SPNT, the RT-PCR method detected, as with virus isolation, a much lower number of positive cases; reasons for this discrepancy are discussed. Our results indicate that RT-PCR can not only be successfully applied in field surveys, but may also be slightly more sensitive than virus......This study compared the results of reverse transcription-polymerase chain reaction (RT-PCR) and traditional virus isolation on cell culture in detection of viral haemorrhagic septicaemia virus (VHSV) and infectious haematopoietic necrosis virus (IHNV). RT-PCR was used for 172 tissue sample pools...... (total of 859 fish) originating from a field survey on the occurrence of VHSV and IHNV in farmed and wild salmonids in Switzerland. These samples represented all sites with fish that were either identified as virus-positive by means of virus isolation (three sites, four positive tissue sample pools) and...

  3. Evaluation of alternative age-based methods for estimating relative abundance from survey data in relation to assessment models

    DEFF Research Database (Denmark)

    Berg, Casper Willestofte; Nielsen, Anders; Kristensen, Kasper

    2014-01-01

    Indices of abundance from fishery-independent trawl surveys constitute an important source of information for many fish stock assessments. Indices are often calculated using area stratified sample means on age-disaggregated data, and finally treated in stock assessment models as independent...... observations. We evaluate a series of alternative methods for calculating indices of abundance from trawl survey data (delta-lognormal, delta-gamma, and Tweedie using Generalized Additive Models) as well as different error structures for these indices when used as input in an age-based stock assessment model...... the different indices produced. The stratified mean method is found much more imprecise than the alternatives based on GAMs, which are found to be similar. Having time-varying index variances is found to be of minor importance, whereas the independence assumption is not only violated but has significant impact...

  4. Terrestrial gamma radiation baseline mapping using ultra low density sampling methods.

    Science.gov (United States)

    Kleinschmidt, R; Watson, D

    2016-01-01

    Baseline terrestrial gamma radiation maps are indispensable for providing basic reference information that may be used in assessing the impact of a radiation related incident, performing epidemiological studies, remediating land contaminated with radioactive materials, assessment of land use applications and resource prospectivity. For a large land mass, such as Queensland, Australia (over 1.7 million km(2)), it is prohibitively expensive and practically difficult to undertake detailed in-situ radiometric surveys of this scale. It is proposed that an existing, ultra-low density sampling program already undertaken for the purpose of a nationwide soil survey project be utilised to develop a baseline terrestrial gamma radiation map. Geoelement data derived from the National Geochemistry Survey of Australia (NGSA) was used to construct a baseline terrestrial gamma air kerma rate map, delineated by major drainage catchments, for Queensland. Three drainage catchments (sampled at the catchment outlet) spanning low, medium and high radioelement concentrations were selected for validation of the methodology using radiometric techniques including in-situ measurements and soil sampling for high resolution gamma spectrometry, and comparative non-radiometric analysis. A Queensland mean terrestrial air kerma rate, as calculated from the NGSA outlet sediment uranium, thorium and potassium concentrations, of 49 ± 69 nGy h(-1) (n = 311, 3σ 99% confidence level) is proposed as being suitable for use as a generic terrestrial air kerma rate background range. Validation results indicate that catchment outlet measurements are representative of the range of results obtained across the catchment and that the NGSA geoelement data is suitable for calculation and mapping of terrestrial air kerma rate. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  5. Method and apparatus for sampling atmospheric mercury

    Science.gov (United States)

    Trujillo, Patricio E.; Campbell, Evan E.; Eutsler, Bernard C.

    1976-01-20

    A method of simultaneously sampling particulate mercury, organic mercurial vapors, and metallic mercury vapor in the working and occupational environment and determining the amount of mercury derived from each such source in the sampled air. A known volume of air is passed through a sampling tube containing a filter for particulate mercury collection, a first adsorber for the selective adsorption of organic mercurial vapors, and a second adsorber for the adsorption of metallic mercury vapor. Carbon black molecular sieves are particularly useful as the selective adsorber for organic mercurial vapors. The amount of mercury adsorbed or collected in each section of the sampling tube is readily quantitatively determined by flameless atomic absorption spectrophotometry.

  6. A Survey for Spectroscopic Binaries in a Large Sample of G Dwarfs

    Science.gov (United States)

    Udry, S.; Mayor, M.; Latham, D. W.; Stefanik, R. P.; Torres, G.; Mazeh, T.; Goldberg, D.; Andersen, J.; Nordstrom, B.

    For more than 5 years now, the radial velocities for a large sample of G dwarfs (3,347 stars) have been monitored in order to obtain an unequaled set of orbital parameters for solar-type stars (~400 orbits, up to now). This survey provides a considerable improvement on the classical systematic study by Duquennoy and Mayor (1991; DM91). The observational part of the survey has been carried out in the context of a collaboration between the Geneva Observatory on the two coravel spectrometers for the southern sky and CfA at Oakridge and Whipple Observatories for the northern sky. As a first glance at these new results, we will address in this contribution a special aspect of the orbital eccentricity distribution, namely the disappearance of the void observed in DM91 for quasi-circular orbits with periods larger than 10 days.

  7. Regional soil erosion assessment based on a sample survey and geostatistics

    Directory of Open Access Journals (Sweden)

    S. Yin

    2018-03-01

    Full Text Available Soil erosion is one of the most significant environmental problems in China. From 2010 to 2012, the fourth national census for soil erosion sampled 32 364 PSUs (Primary Sampling Units, small watersheds with the areas of 0.2–3 km2. Land use and soil erosion controlling factors including rainfall erosivity, soil erodibility, slope length, slope steepness, biological practice, engineering practice, and tillage practice for the PSUs were surveyed, and the soil loss rate for each land use in the PSUs was estimated using an empirical model, the Chinese Soil Loss Equation (CSLE. Though the information collected from the sample units can be aggregated to estimate soil erosion conditions on a large scale; the problem of estimating soil erosion condition on a regional scale has not been addressed well. The aim of this study is to introduce a new model-based regional soil erosion assessment method combining a sample survey and geostatistics. We compared seven spatial interpolation models based on the bivariate penalized spline over triangulation (BPST method to generate a regional soil erosion assessment from the PSUs. Shaanxi Province (3116 PSUs in China was selected for the comparison and assessment as it is one of the areas with the most serious erosion problem. Ten-fold cross-validation based on the PSU data showed the model assisted by the land use, rainfall erosivity factor (R, soil erodibility factor (K, slope steepness factor (S, and slope length factor (L derived from a 1 : 10 000 topography map is the best one, with the model efficiency coefficient (ME being 0.75 and the MSE being 55.8 % of that for the model assisted by the land use alone. Among four erosion factors as the covariates, the S factor contributed the most information, followed by K and L factors, and R factor made almost no contribution to the spatial estimation of soil loss. The LS factor derived from 30 or 90 m Shuttle Radar Topography Mission

  8. A Sequential Optimization Sampling Method for Metamodels with Radial Basis Functions

    Science.gov (United States)

    Pan, Guang; Ye, Pengcheng; Yang, Zhidong

    2014-01-01

    Metamodels have been widely used in engineering design to facilitate analysis and optimization of complex systems that involve computationally expensive simulation programs. The accuracy of metamodels is strongly affected by the sampling methods. In this paper, a new sequential optimization sampling method is proposed. Based on the new sampling method, metamodels can be constructed repeatedly through the addition of sampling points, namely, extrema points of metamodels and minimum points of density function. Afterwards, the more accurate metamodels would be constructed by the procedure above. The validity and effectiveness of proposed sampling method are examined by studying typical numerical examples. PMID:25133206

  9. Primer on Health Surveys

    Directory of Open Access Journals (Sweden)

    David L Nordstrom

    2012-06-01

    Full Text Available The aim of this paper is to introduce novice researchers to surveys as a method of data collection. It starts with the definition of a survey, its major purposes and types as well as changes in the goals surveys have helped to achieve over time. Advantages and disadvantages of surveys over population censuses and medical examinations are discussed. Approaches to questionnaire construction are introduced along with properties that questionnaires are evaluated for. Modes of administration, sample size issues, and data analysis approaches are also introduced. The primer is illustrated with examples of surveys conducted in different countries with various public health purposes.

  10. Survey Method for Radiological Surveys of 300-FF-1 Operable Unit Soils and Material

    International Nuclear Information System (INIS)

    Brehm, D.M.

    1998-06-01

    This technical basis is to be used to survey soils at the 300-FF-1 Operable Unit during remediation of the site. Its purpose is to provide a basis for the survey methods to be employed by radiological control technician (RCTs) to guide the excavation effort in accordance with the 300-FF-1 waste site Record of Decision (ROD). The ROD for the 300-FF-1 Operable Unit requires selective excavation, removal, and disposal of contaminated soil above 350 pCi/g total uranium activity. Soil above this level will be disposed of as radioactive waste. The remaining soil will remain onsite

  11. Characterizing lentic freshwater fish assemblages using multiple sampling methods

    Science.gov (United States)

    Fischer, Jesse R.; Quist, Michael C.

    2014-01-01

    Characterizing fish assemblages in lentic ecosystems is difficult, and multiple sampling methods are almost always necessary to gain reliable estimates of indices such as species richness. However, most research focused on lentic fish sampling methodology has targeted recreationally important species, and little to no information is available regarding the influence of multiple methods and timing (i.e., temporal variation) on characterizing entire fish assemblages. Therefore, six lakes and impoundments (48–1,557 ha surface area) were sampled seasonally with seven gear types to evaluate the combined influence of sampling methods and timing on the number of species and individuals sampled. Probabilities of detection for species indicated strong selectivities and seasonal trends that provide guidance on optimal seasons to use gears when targeting multiple species. The evaluation of species richness and number of individuals sampled using multiple gear combinations demonstrated that appreciable benefits over relatively few gears (e.g., to four) used in optimal seasons were not present. Specifically, over 90 % of the species encountered with all gear types and season combinations (N = 19) from six lakes and reservoirs were sampled with nighttime boat electrofishing in the fall and benthic trawling, modified-fyke, and mini-fyke netting during the summer. Our results indicated that the characterization of lentic fish assemblages was highly influenced by the selection of sampling gears and seasons, but did not appear to be influenced by waterbody type (i.e., natural lake, impoundment). The standardization of data collected with multiple methods and seasons to account for bias is imperative to monitoring of lentic ecosystems and will provide researchers with increased reliability in their interpretations and decisions made using information on lentic fish assemblages.

  12. THE SLOAN DIGITAL SKY SURVEY QUASAR LENS SEARCH. IV. STATISTICAL LENS SAMPLE FROM THE FIFTH DATA RELEASE

    International Nuclear Information System (INIS)

    Inada, Naohisa; Oguri, Masamune; Shin, Min-Su; Kayo, Issha; Fukugita, Masataka; Strauss, Michael A.; Gott, J. Richard; Hennawi, Joseph F.; Morokuma, Tomoki; Becker, Robert H.; Gregg, Michael D.; White, Richard L.; Kochanek, Christopher S.; Chiu, Kuenley; Johnston, David E.; Clocchiatti, Alejandro; Richards, Gordon T.; Schneider, Donald P.; Frieman, Joshua A.

    2010-01-01

    We present the second report of our systematic search for strongly lensed quasars from the data of the Sloan Digital Sky Survey (SDSS). From extensive follow-up observations of 136 candidate objects, we find 36 lenses in the full sample of 77,429 spectroscopically confirmed quasars in the SDSS Data Release 5. We then define a complete sample of 19 lenses, including 11 from our previous search in the SDSS Data Release 3, from the sample of 36,287 quasars with i Λ = 0.84 +0.06 -0.08 (stat.) +0.09 -0.07 (syst.) assuming a flat universe, which is in good agreement with other cosmological observations. We also report the discoveries of seven binary quasars with separations ranging from 1.''1 to 16.''6, which are identified in the course of our lens survey. This study concludes the construction of our statistical lens sample in the full SDSS-I data set.

  13. Optical methods for microstructure determination of doped samples

    Science.gov (United States)

    Ciosek, Jerzy F.

    2008-12-01

    The optical methods to determine refractive index profile of layered materials are commonly used with spectroscopic ellipsometry or transmittance/reflectance spectrometry. Measurements of spectral reflection and transmission usually permit to characterize optical materials and determine their refractive index. However, it is possible to characterize of samples with dopants, impurities as well as defects using optical methods. Microstructures of a hydrogenated crystalline Si wafer and a layer of SiO2 - ZrO2 composition are investigated. The first sample is a Si(001):H Czochralski grown single crystalline wafer with 50 nm thick surface Si02 layer. Hydrogen dose implantation (D continue to be an important issue in microelectronic device and sensor fabrication. Hydrogen-implanted silicon (Si: H) has become a topic of remarkable interest, mostly because of the potential of implantation-induced platelets and micro-cavities for the creation of gettering -active areas and for Si layer splitting. Oxygen precipitation and atmospheric impurity are analysed. The second sample is the layer of co-evaporated SiO2 and ZrO2 materials using simultaneously two electron beam guns in reactive evaporation methods. The composition structure was investigated by X-Ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry methods. A non-uniformity and composition of layer are analysed using average density method.

  14. Customer satisfaction surveys: Methodological recommendations for financial service providers

    Directory of Open Access Journals (Sweden)

    Đorđić Marko

    2010-01-01

    Full Text Available This methodological article investigates practical challenges that emerge when conducting customer satisfaction surveys (CSS for financial service providers such as banks, insurance or leasing companies, and so forth. It displays methodological recommendations in reference with: (a survey design, (b sampling, (c survey method, (d questionnaire design, and (e data acquisition. Article provides appropriate explanations that usage of: two-stage survey design, SRS method, large samples, and rigorous fieldwork preparation can enhance the overall quality of CSS in financial services. Proposed methodological recommendations can primarily be applied to the primary quantitative marketing research in retail financial services. However, majority of them can be successfully applied when conducting primary quantitative marketing research in corporate financial services as well. .

  15. A comparison of four sampling methods among men having sex with men in China: implications for HIV/STD surveillance and prevention

    Science.gov (United States)

    Guo, Yan; Li, Xiaoming; Fang, Xiaoyi; Lin, Xiuyun; Song, Yan; Jiang, Shuling; Stanton, Bonita

    2011-01-01

    Sample representativeness remains one of the challenges in effective HIV/STD surveillance and prevention targeting MSM worldwide. Although convenience samples are widely used in studies of MSM, previous studies suggested that these samples might not be representative of the broader MSM population. This issue becomes even more critical in many developing countries where needed resources for conducting probability sampling are limited. We examined variations in HIV and Syphilis infections and sociodemographic and behavioral factors among 307 young migrant MSM recruited using four different convenience sampling methods (peer outreach, informal social network, Internet, and venue-based) in Beijing, China in 2009. The participants completed a self-administered survey and provided blood specimens for HIV/STD testing. Among the four MSM samples using different recruitment methods, rates of HIV infections were 5.1%, 5.8%, 7.8%, and 3.4%; rates of Syphilis infection were 21.8%, 36.2%, 11.8%, and 13.8%; rates of inconsistent condom use were 57%, 52%, 58%, and 38%. Significant differences were found in various sociodemographic characteristics (e.g., age, migration history, education, income, places of employment) and risk behaviors (e.g., age at first sex, number of sex partners, involvement in commercial sex, and substance use) among samples recruited by different sampling methods. The results confirmed the challenges of obtaining representative MSM samples and underscored the importance of using multiple sampling methods to reach MSM from diverse backgrounds and in different social segments and to improve the representativeness of the MSM samples when the use of probability sampling approach is not feasible. PMID:21711162

  16. Comparing two remote video survey methods for spatial predictions of the distribution and environmental niche suitability of demersal fishes.

    Science.gov (United States)

    Galaiduk, Ronen; Radford, Ben T; Wilson, Shaun K; Harvey, Euan S

    2017-12-15

    Information on habitat associations from survey data, combined with spatial modelling, allow the development of more refined species distribution modelling which may identify areas of high conservation/fisheries value and consequentially improve conservation efforts. Generalised additive models were used to model the probability of occurrence of six focal species after surveys that utilised two remote underwater video sampling methods (i.e. baited and towed video). Models developed for the towed video method had consistently better predictive performance for all but one study species although only three models had a good to fair fit, and the rest were poor fits, highlighting the challenges associated with modelling habitat associations of marine species in highly homogenous, low relief environments. Models based on baited video dataset regularly included large-scale measures of structural complexity, suggesting fish attraction to a single focus point by bait. Conversely, models based on the towed video data often incorporated small-scale measures of habitat complexity and were more likely to reflect true species-habitat relationships. The cost associated with use of the towed video systems for surveying low-relief seascapes was also relatively low providing additional support for considering this method for marine spatial ecological modelling.

  17. Evaluation of sampling methods for Bacillus spore-contaminated HVAC filters.

    Science.gov (United States)

    Calfee, M Worth; Rose, Laura J; Tufts, Jenia; Morse, Stephen; Clayton, Matt; Touati, Abderrahmane; Griffin-Gatchalian, Nicole; Slone, Christina; McSweeney, Neal

    2014-01-01

    The objective of this study was to compare an extraction-based sampling method to two vacuum-based sampling methods (vacuum sock and 37mm cassette filter) with regards to their ability to recover Bacillus atrophaeus spores (surrogate for Bacillus anthracis) from pleated heating, ventilation, and air conditioning (HVAC) filters that are typically found in commercial and residential buildings. Electrostatic and mechanical HVAC filters were tested, both without and after loading with dust to 50% of their total holding capacity. The results were analyzed by one-way ANOVA across material types, presence or absence of dust, and sampling device. The extraction method gave higher relative recoveries than the two vacuum methods evaluated (p≤0.001). On average, recoveries obtained by the vacuum methods were about 30% of those achieved by the extraction method. Relative recoveries between the two vacuum methods were not significantly different (p>0.05). Although extraction methods yielded higher recoveries than vacuum methods, either HVAC filter sampling approach may provide a rapid and inexpensive mechanism for understanding the extent of contamination following a wide-area biological release incident. Published by Elsevier B.V.

  18. Radiochemistry methods in DOE methods for evaluating environmental and waste management samples

    International Nuclear Information System (INIS)

    Fadeff, S.K.; Goheen, S.C.

    1994-08-01

    Current standard sources of radiochemistry methods are often inappropriate for use in evaluating US Department of Energy environmental and waste management (DOE/EW) samples. Examples of current sources include EPA, ASTM, Standard Methods for the Examination of Water and Wastewater and HASL-300. Applicability of these methods is limited to specific matrices (usually water), radiation levels (usually environmental levels), and analytes (limited number). Radiochemistry methods in DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) attempt to fill the applicability gap that exists between standard methods and those needed for DOE/EM activities. The Radiochemistry chapter in DOE Methods includes an ''analysis and reporting'' guidance section as well as radiochemistry methods. A basis for identifying the DOE/EM radiochemistry needs is discussed. Within this needs framework, the applicability of standard methods and targeted new methods is identified. Sources of new methods (consolidated methods from DOE laboratories and submissions from individuals) and the methods review process will be discussed. The processes involved in generating consolidated methods add editing individually submitted methods will be compared. DOE Methods is a living document and continues to expand by adding various kinds of methods. Radiochemistry methods are highlighted in this paper. DOE Methods is intended to be a resource for methods applicable to DOE/EM problems. Although it is intended to support DOE, the guidance and methods are not necessarily exclusive to DOE. The document is available at no cost through the Laboratory Management Division of DOE, Office of Technology Development

  19. Measuring fertility through mobile‒phone based household surveys: Methods, data quality, and lessons learned from PMA2020 surveys

    OpenAIRE

    Yoonjoung Choi; Qingfeng Li; Blake Zachary

    2018-01-01

    Background: PMA2020 is a survey platform with resident enumerators using mobile phones. Instead of collecting full birth history, total fertility rates (TFR) have been measured with a limited number of questions on recent births. Employing new approaches provides opportunities to test and advance survey methods. Objective: This study aims to assess the quality of fertility data in PMA2020 surveys, focusing on bias introduced from the questionnaire and completeness and distribution of birth...

  20. Evaluation of field sampling and preservation methods for strontium-90 in ground water at the Idaho National Engineering Laboratory, Idaho

    International Nuclear Information System (INIS)

    Cecil, L.D.; Knobel, L.L.; Wegner, S.J.; Moore, L.L.

    1989-01-01

    Water from four wells completed in the Snake River Plain aquifer was sampled as part of the US Geological Survey's quality assurance program to evaluate the effect of filtration and preservation methods on strontium-90 concentrations in groundwater at the Idaho National Engineering Laboratory. Water from each well was filtered through either a 0.45-micrometer membrane or a 0.1-micrometer membrane filter; unfiltered samples also were collected. Two sets of filtered and two sets of unfiltered samples was preserved in the field with reagent-grade hydrochloric acid and the other set of samples was not acidified. For water from wells with strontium-90 concentrations at or above the reporting level, 94% or more of the strontium-90 is in true solution or in colloidal particles smaller than 0.1 micrometer. These results suggest that within-laboratory reproducibility for strontium-90 in groundwater at the INEL is not significantly affected by changes in filtration and preservation methods used for sample collections. 13 refs., 2 figs., 6 tabs

  1. Prevalence of coronary artery disease and coronary risk factors in Kerala, South India: A population survey – Design and methods

    Directory of Open Access Journals (Sweden)

    Geevar Zachariah

    2013-05-01

    Methods: The design of the study was cross-sectional population survey. We estimated the sample size based on an anticipated prevalence of 7.4% of CAD for rural and 11% for urban Kerala. The derived sample sizes for rural and urban areas were 3000 and 2400, respectively. The urban areas for sampling constituted one ward each from three municipal corporations at different parts of the state. The rural sample was drawn from two panchayats each in the same districts as the urban sample. One adult from each household in the age group of 20–59 years was selected using Kish method. All subjects between 60 and 79 years were included from each household. A detailed questionnaire was administered to assess the risk factors, history of CAD, family history, educational status, socioeconomic status, dietary habits, physical activity and treatment for CAD; anthropometric measurements, blood pressure, electrocardiogram and fasting blood levels of glucose and lipids were recorded.

  2. 7 CFR 51.308 - Methods of sampling and calculation of percentages.

    Science.gov (United States)

    2010-01-01

    ..., CERTIFICATION, AND STANDARDS) United States Standards for Grades of Apples Methods of Sampling and Calculation of Percentages § 51.308 Methods of sampling and calculation of percentages. (a) When the numerical... 7 Agriculture 2 2010-01-01 2010-01-01 false Methods of sampling and calculation of percentages. 51...

  3. Methods for the collection of subsurface samples during environmental site assessments

    International Nuclear Information System (INIS)

    Weinstock, E.A.

    1996-01-01

    This paper discusses numerous sample collection techniques that have been successfully employed during Phase 2 Assessments and presents case histories of their application. Pollutants of concern include PCE and petroleum. The collection of shallow soil samples is described using commercially available hand augers and hand-driven core samplers. These devices are modified with extensions to collect deeper samples from storm drains and leaching pools. The performance of soil gas surveys are described using both hand-driven sample probes and vehicle-mounted, hydraulically driven vapor probes. Once the soil vapor is collected at the ground surface, a sample of the media is either analyzed on-site using a field-operated detection device or delivered to a laboratory for analysis. Application and case histories of the Geoprobe(trademark)sampling system, a form of direct push technology, are described. This device uses vehicle-mounted, hydraulically-driven sample probes. The probe can be advanced to depths as great as 100 feet below grade and can retrieve soil, soil gas and groundwater samples

  4. Health inequalities: survey data compared to doctor defined data.

    NARCIS (Netherlands)

    Westert, G.P.; Schellevis, F.G.

    2003-01-01

    Aim: To compare prevalence of conditions and health inequalities in one study population using two methods of data collection: health interview survey and GP registration of consultations. Methods: Data is from the Second Dutch Survey of General Practice, using a multistage sampling design with

  5. Comparing Traditional and Crowdsourcing Methods for Pretesting Survey Questions

    Directory of Open Access Journals (Sweden)

    Jennifer Edgar

    2016-10-01

    Full Text Available Cognitive interviewing is a common method used to evaluate survey questions. This study compares traditional cognitive interviewing methods with crowdsourcing, or “tapping into the collective intelligence of the public to complete a task.” Crowdsourcing may provide researchers with access to a diverse pool of potential participants in a very timely and cost-efficient way. Exploratory work found that crowdsourcing participants, with self-administered data collection, may be a viable alternative, or addition, to traditional pretesting methods. Using three crowdsourcing designs (TryMyUI, Amazon Mechanical Turk, and Facebook, we compared the participant characteristics, costs, and quantity and quality of data with traditional laboratory-based cognitive interviews. Results suggest that crowdsourcing and self-administered protocols may be a viable way to collect survey pretesting information, as participants were able to complete the tasks and provide useful information; however, complex tasks may require the skills of an interviewer to administer unscripted probes.

  6. Further observations on comparison of immunization coverage by lot quality assurance sampling and 30 cluster sampling.

    Science.gov (United States)

    Singh, J; Jain, D C; Sharma, R S; Verghese, T

    1996-06-01

    Lot Quality Assurance Sampling (LQAS) and standard EPI methodology (30 cluster sampling) were used to evaluate immunization coverage in a Primary Health Center (PHC) where coverage levels were reported to be more than 85%. Of 27 sub-centers (lots) evaluated by LQAS, only 2 were accepted for child coverage, whereas none was accepted for tetanus toxoid (TT) coverage in mothers. LQAS data were combined to obtain an estimate of coverage in the entire population; 41% (95% CI 36-46) infants were immunized appropriately for their ages, while 42% (95% CI 37-47) of their mothers had received a second/ booster dose of TT. TT coverage in 149 contemporary mothers sampled in EPI survey was also 42% (95% CI 31-52). Although results by the two sampling methods were consistent with each other, a big gap was evident between reported coverage (in children as well as mothers) and survey results. LQAS was found to be operationally feasible, but it cost 40% more and required 2.5 times more time than the EPI survey. LQAS therefore, is not a good substitute for current EPI methodology to evaluate immunization coverage in a large administrative area. However, LQAS has potential as method to monitor health programs on a routine basis in small population sub-units, especially in areas with high and heterogeneously distributed immunization coverage.

  7. Review of Estimation Methods for Landline and Cell Phone Surveys

    Science.gov (United States)

    Arcos, Antonio; del Mar Rueda, María; Trujillo, Manuel; Molina, David

    2015-01-01

    The rapid proliferation of cell phone use and the accompanying decline in landline service in recent years have resulted in substantial potential for coverage bias in landline random-digit-dial telephone surveys, which has led to the implementation of dual-frame designs that incorporate both landline and cell phone samples. Consequently,…

  8. Sampling trace organic compounds in water: a comparison of a continuous active sampler to continuous passive and discrete sampling methods.

    Science.gov (United States)

    Coes, Alissa L; Paretti, Nicholas V; Foreman, William T; Iverson, Jana L; Alvarez, David A

    2014-03-01

    A continuous active sampling method was compared to continuous passive and discrete sampling methods for the sampling of trace organic compounds (TOCs) in water. Results from each method are compared and contrasted in order to provide information for future investigators to use while selecting appropriate sampling methods for their research. The continuous low-level aquatic monitoring (CLAM) sampler (C.I.Agent® Storm-Water Solutions) is a submersible, low flow-rate sampler, that continuously draws water through solid-phase extraction media. CLAM samplers were deployed at two wastewater-dominated stream field sites in conjunction with the deployment of polar organic chemical integrative samplers (POCIS) and the collection of discrete (grab) water samples. All samples were analyzed for a suite of 69 TOCs. The CLAM and POCIS samples represent time-integrated samples that accumulate the TOCs present in the water over the deployment period (19-23 h for CLAM and 29 days for POCIS); the discrete samples represent only the TOCs present in the water at the time and place of sampling. Non-metric multi-dimensional scaling and cluster analysis were used to examine patterns in both TOC detections and relative concentrations between the three sampling methods. A greater number of TOCs were detected in the CLAM samples than in corresponding discrete and POCIS samples, but TOC concentrations in the CLAM samples were significantly lower than in the discrete and (or) POCIS samples. Thirteen TOCs of varying polarity were detected by all of the three methods. TOC detections and concentrations obtained by the three sampling methods, however, are dependent on multiple factors. This study found that stream discharge, constituent loading, and compound type all affected TOC concentrations detected by each method. In addition, TOC detections and concentrations were affected by the reporting limits, bias, recovery, and performance of each method. Published by Elsevier B.V.

  9. Sampling trace organic compounds in water: a comparison of a continuous active sampler to continuous passive and discrete sampling methods

    Science.gov (United States)

    Coes, Alissa L.; Paretti, Nicholas V.; Foreman, William T.; Iverson, Jana L.; Alvarez, David A.

    2014-01-01

    A continuous active sampling method was compared to continuous passive and discrete sampling methods for the sampling of trace organic compounds (TOCs) in water. Results from each method are compared and contrasted in order to provide information for future investigators to use while selecting appropriate sampling methods for their research. The continuous low-level aquatic monitoring (CLAM) sampler (C.I.Agent® Storm-Water Solutions) is a submersible, low flow-rate sampler, that continuously draws water through solid-phase extraction media. CLAM samplers were deployed at two wastewater-dominated stream field sites in conjunction with the deployment of polar organic chemical integrative samplers (POCIS) and the collection of discrete (grab) water samples. All samples were analyzed for a suite of 69 TOCs. The CLAM and POCIS samples represent time-integrated samples that accumulate the TOCs present in the water over the deployment period (19–23 h for CLAM and 29 days for POCIS); the discrete samples represent only the TOCs present in the water at the time and place of sampling. Non-metric multi-dimensional scaling and cluster analysis were used to examine patterns in both TOC detections and relative concentrations between the three sampling methods. A greater number of TOCs were detected in the CLAM samples than in corresponding discrete and POCIS samples, but TOC concentrations in the CLAM samples were significantly lower than in the discrete and (or) POCIS samples. Thirteen TOCs of varying polarity were detected by all of the three methods. TOC detections and concentrations obtained by the three sampling methods, however, are dependent on multiple factors. This study found that stream discharge, constituent loading, and compound type all affected TOC concentrations detected by each method. In addition, TOC detections and concentrations were affected by the reporting limits, bias, recovery, and performance of each method.

  10. Soil sampling for environmental contaminants

    International Nuclear Information System (INIS)

    2004-10-01

    The Consultants Meeting on Sampling Strategies, Sampling and Storage of Soil for Environmental Monitoring of Contaminants was organized by the International Atomic Energy Agency to evaluate methods for soil sampling in radionuclide monitoring and heavy metal surveys for identification of punctual contamination (hot particles) in large area surveys and screening experiments. A group of experts was invited by the IAEA to discuss and recommend methods for representative soil sampling for different kinds of environmental issues. The ultimate sinks for all kinds of contaminants dispersed within the natural environment through human activities are sediment and soil. Soil is a particularly difficult matrix for environmental pollution studies as it is generally composed of a multitude of geological and biological materials resulting from weathering and degradation, including particles of different sizes with varying surface and chemical properties. There are so many different soil types categorized according to their content of biological matter, from sandy soils to loam and peat soils, which make analytical characterization even more complicated. Soil sampling for environmental monitoring of pollutants, therefore, is still a matter of debate in the community of soil, environmental and analytical sciences. The scope of the consultants meeting included evaluating existing techniques with regard to their practicability, reliability and applicability to different purposes, developing strategies of representative soil sampling for cases not yet considered by current techniques and recommending validated techniques applicable to laboratories in developing Member States. This TECDOC includes a critical survey of existing approaches and their feasibility to be applied in developing countries. The report is valuable for radioanalytical laboratories in Member States. It would assist them in quality control and accreditation process

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

    Science.gov (United States)

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

    2017-10-01

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

  12. A Survey of Various Object Oriented Requirement Engineering Methods

    OpenAIRE

    Anandi Mahajan; Dr. Anurag Dixit

    2013-01-01

    In current years many industries have been moving to the use of object-oriented methods for the development of large scale information systems The requirement of Object Oriented approach in the development of software systems is increasing day by day. This paper is basically a survey paper on various Object-oriented requirement engineering methods. This paper contains a summary of the available Object-oriented requirement engineering methods with their relative advantages and disadvantages...

  13. Influences of different sample preparation methods on tooth enamel ESR signals

    International Nuclear Information System (INIS)

    Zhang Wenyi; Jiao Ling; Zhang Liang'an; Pan Zhihong; Zeng Hongyu

    2005-01-01

    Objective: To study the influences of different sample preparation methods on tooth enamel ESR signals in order to reduce the effect of dentine on their sensitivities to radiation. Methods: The enamel was separated from dentine of non-irradiated adult teeth by mechanical, chemical, or both methods. The samples of different preparations were scanned by an ESR spectrometer before and after irradiation. Results: The response of ESR signals of samples prepared with different methods to radiation dose was significantly different. Conclusion: The selection of sample preparation method is very important for dose reconstruction by tooth enamel ESR dosimetry, especially in the low dose range. (authors)

  14. Sampling in epidemiological research: issues, hazards and pitfalls

    Science.gov (United States)

    Tyrer, Stephen; Heyman, Bob

    2016-01-01

    Surveys of people's opinions are fraught with difficulties. It is easier to obtain information from those who respond to text messages or to emails than to attempt to obtain a representative sample. Samples of the population that are selected non-randomly in this way are termed convenience samples as they are easy to recruit. This introduces a sampling bias. Such non-probability samples have merit in many situations, but an epidemiological enquiry is of little value unless a random sample is obtained. If a sufficient number of those selected actually complete a survey, the results are likely to be representative of the population. This editorial describes probability and non-probability sampling methods and illustrates the difficulties and suggested solutions in performing accurate epidemiological research. PMID:27087985

  15. The Lyα reference sample. I. Survey outline and first results for Markarian 259

    International Nuclear Information System (INIS)

    Östlin, Göran; Hayes, Matthew; Duval, Florent; Sandberg, Andreas; Rivera-Thorsen, Thøger; Marquart, Thomas; Adamo, Angela; Melinder, Jens; Guaita, Lucia; Micheva, Genoveva; Orlitová, Ivana; Atek, Hakim; Cannon, John M.; Pardy, Stephen A.; Gruyters, Pieter; Herenz, Edmund Christian; Kunth, Daniel; Laursen, Peter; Mas-Hesse, J. Miguel; Otí-Floranes, Héctor

    2014-01-01

    The Lyα Reference Sample (LARS) is a substantial program with the Hubble Space Telescope (HST) that provides a sample of local universe laboratory galaxies in which to study the detailed astrophysics of the visibility and strength of the Lyαline of neutral hydrogen. Lyα is the dominant spectral line in use for characterizing high-redshift (z) galaxies. This paper presents an overview of the survey, its selection function, and HST imaging observations. The sample was selected from the combined GALEX+Sloan Digital Sky Survey catalog at z = 0.028-0.19, in order to allow Lyα to be captured with combinations of long-pass filters in the Solar Blind Channel (SBC) of the Advanced Camera for Surveys (ACS) onboard HST. In addition, LARS utilizes Hα and Hβ narrowband and u, b, i broadband imaging with ACS and the Wide Field Camera 3 (WFC3). In order to study galaxies in which large numbers of Lyα photons are produced (whether or not they escape), we demanded an Hα equivalent width W(Hα) ≥100 Å. The final sample of 14 galaxies covers far-UV (FUV, λ ∼ 1500 Å) luminosities that overlap with those of high-z Lyα emitters (LAEs) and Lyman break galaxies (LBGs), making LARS a valid comparison sample. We present the reduction steps used to obtain the Lyα images, including our LARS eXtraction software (LaXs), which utilizes pixel-by-pixel spectral synthesis fitting of the energy distribution to determine and subtract the continuum at Lyα. We demonstrate that the use of SBC long-pass-filter combinations increase the signal-to-noise ratio by an order of magnitude compared to the nominal Lyα filter available in SBC. To exemplify the science potential of LARS, we also present some first results for a single galaxy, Mrk 259 (LARS #1). This irregular galaxy shows bright and extended (indicative of resonance scattering) but strongly asymmetric Lyα emission. Spectroscopy from the Cosmic Origins Spectrograph on board HST centered on the brightest UV knot shows a moderate

  16. The Lyα reference sample. I. Survey outline and first results for Markarian 259

    Energy Technology Data Exchange (ETDEWEB)

    Östlin, Göran; Hayes, Matthew; Duval, Florent; Sandberg, Andreas; Rivera-Thorsen, Thøger; Marquart, Thomas; Adamo, Angela; Melinder, Jens; Guaita, Lucia; Micheva, Genoveva [Department of Astronomy, Stockholm University, Oscar Klein Centre, AlbaNova, Stockholm SE-106 91 (Sweden); Orlitová, Ivana [Observatoire de Genève, Université de Genève, Chemin des Maillettes 51, 1290 Versoix (Switzerland); Atek, Hakim [Laboratoire d' Astrophysique, Ecole Polytechnique Fédérale de Lausanne, Observatoire de Sauverny, CH-1290 Versoix (Switzerland); Cannon, John M.; Pardy, Stephen A. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Gruyters, Pieter [Department of Physics and Astronomy, Division of Astronomy and Space Physics, Uppsala University, Box 516, 75120 Uppsala (Sweden); Herenz, Edmund Christian [Leibniz-Institute for Astrophysics Potsdam (AIP), innoFSPEC, An der Sternwarte 16, D-14482 Potsdam (Germany); Kunth, Daniel [Institut d' Astrophysique Paris, 98bis Bd Arago, F-75014 Paris (France); Laursen, Peter [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark); Mas-Hesse, J. Miguel [Centro de Astrobiologa (CSIC-INTA), Departamento de Astrofsica, POB 78, E-28691, Villanueva de la Cañada (Spain); Otí-Floranes, Héctor [Instituto de Astronoma, Universidad Nacional Autnoma de Mxico, Apdo. Postal 106, Ensenada B. C. 22800 (Mexico); and others

    2014-12-10

    The Lyα Reference Sample (LARS) is a substantial program with the Hubble Space Telescope (HST) that provides a sample of local universe laboratory galaxies in which to study the detailed astrophysics of the visibility and strength of the Lyαline of neutral hydrogen. Lyα is the dominant spectral line in use for characterizing high-redshift (z) galaxies. This paper presents an overview of the survey, its selection function, and HST imaging observations. The sample was selected from the combined GALEX+Sloan Digital Sky Survey catalog at z = 0.028-0.19, in order to allow Lyα to be captured with combinations of long-pass filters in the Solar Blind Channel (SBC) of the Advanced Camera for Surveys (ACS) onboard HST. In addition, LARS utilizes Hα and Hβ narrowband and u, b, i broadband imaging with ACS and the Wide Field Camera 3 (WFC3). In order to study galaxies in which large numbers of Lyα photons are produced (whether or not they escape), we demanded an Hα equivalent width W(Hα) ≥100 Å. The final sample of 14 galaxies covers far-UV (FUV, λ ∼ 1500 Å) luminosities that overlap with those of high-z Lyα emitters (LAEs) and Lyman break galaxies (LBGs), making LARS a valid comparison sample. We present the reduction steps used to obtain the Lyα images, including our LARS eXtraction software (LaXs), which utilizes pixel-by-pixel spectral synthesis fitting of the energy distribution to determine and subtract the continuum at Lyα. We demonstrate that the use of SBC long-pass-filter combinations increase the signal-to-noise ratio by an order of magnitude compared to the nominal Lyα filter available in SBC. To exemplify the science potential of LARS, we also present some first results for a single galaxy, Mrk 259 (LARS #1). This irregular galaxy shows bright and extended (indicative of resonance scattering) but strongly asymmetric Lyα emission. Spectroscopy from the Cosmic Origins Spectrograph on board HST centered on the brightest UV knot shows a moderate

  17. Methodology of the National School-based Health Survey in Malaysia, 2012.

    Science.gov (United States)

    Yusoff, Fadhli; Saari, Riyanti; Naidu, Balkish M; Ahmad, Noor Ani; Omar, Azahadi; Aris, Tahir

    2014-09-01

    The National School-Based Health Survey 2012 was a nationwide school health survey of students in Standard 4 to Form 5 (10-17 years of age), who were schooling in government schools in Malaysia during the period of data collection. The survey comprised 3 subsurveys: the Global School Health Survey (GSHS), the Mental Health Survey, and the National School-Based Nutrition Survey. The aim of the survey was to provide data on the health status of adolescents in Malaysia toward strengthening the adolescent health program in the country. The design of the survey was created to fulfill the requirements of the 3 subsurveys. A 2-stage stratified sampling method was adopted in the sampling. The methods for data collection were via questionnaire and physical examination. The National School-Based Health Survey 2012 adopted an appropriate methodology for a school-based survey to ensure valid and reliable findings. © 2014 APJPH.

  18. Methods to characterize environmental settings of stream and groundwater sampling sites for National Water-Quality Assessment

    Science.gov (United States)

    Nakagaki, Naomi; Hitt, Kerie J.; Price, Curtis V.; Falcone, James A.

    2012-01-01

    Characterization of natural and anthropogenic features that define the environmental settings of sampling sites for streams and groundwater, including drainage basins and groundwater study areas, is an essential component of water-quality and ecological investigations being conducted as part of the U.S. Geological Survey's National Water-Quality Assessment program. Quantitative characterization of environmental settings, combined with physical, chemical, and biological data collected at sampling sites, contributes to understanding the status of, and influences on, water-quality and ecological conditions. To support studies for the National Water-Quality Assessment program, a geographic information system (GIS) was used to develop a standard set of methods to consistently characterize the sites, drainage basins, and groundwater study areas across the nation. This report describes three methods used for characterization-simple overlay, area-weighted areal interpolation, and land-cover-weighted areal interpolation-and their appropriate applications to geographic analyses that have different objectives and data constraints. In addition, this document records the GIS thematic datasets that are used for the Program's national design and data analyses.

  19. Survalytics: An Open-Source Cloud-Integrated Experience Sampling, Survey, and Analytics and Metadata Collection Module for Android Operating System Apps

    Science.gov (United States)

    Mackey, Sean

    2016-01-01

    Background We describe here Survalytics, a software module designed to address two broad areas of need. The first area is in the domain of surveys and app analytics: developers of mobile apps in both academic and commercial environments require information about their users, as well as how the apps are being used, to understand who their users are and how to optimally approach app development. The second area of need is in the field of ecological momentary assessment, also referred to as experience sampling: researchers in a wide variety of fields, spanning from the social sciences to psychology to clinical medicine, would like to be able to capture daily or even more frequent data from research subjects while in their natural environment. Objective Survalytics is an open-source solution for the collection of survey responses as well as arbitrary analytic metadata from users of Android operating system apps. Methods Surveys may be administered in any combination of one-time questions and ongoing questions. The module may be deployed as a stand-alone app for experience sampling purposes or as an add-on to existing apps. The module takes advantage of free-tier NoSQL cloud database management offered by the Amazon Web Services DynamoDB platform to package a secure, flexible, extensible data collection module. DynamoDB is capable of Health Insurance Portability and Accountability Act compliant storage of personal health information. Results The provided example app may be used without modification for a basic experience sampling project, and we provide example questions for daily collection of blood glucose data from study subjects. Conclusions The module will help researchers in a wide variety of fields rapidly develop tailor-made Android apps for a variety of data collection purposes. PMID:27261155

  20. Fuel- and wood consumption surveys in developing countries: a proposal of an efficient low-cost method and the results of its application in eastern Ethiopia

    Energy Technology Data Exchange (ETDEWEB)

    Poschen, P.; Eiche, G.

    1986-01-01

    The method involves a preliminary survey to establish areas homogeneous for temperature and rainfall regime, natural vegetation, agricultural systems, wood fuel substitutes, housing and cooking habits. Locations are sampled within such areas to reflect variability in presence of forests and other fuel and wood resources, population density, and access to markets. Households are sampled within a location to cover variation in social structure. Results from a survey in the Hararghe highlands differ markedly from previous Ethiopia-wide estimates and show that remaining wood resources supply less than half of the fuel requirements. An effective community forestry programme is urgently required. (Refs. 9).

  1. Creel survey sampling designs for estimating effort in short-duration Chinook salmon fisheries

    Science.gov (United States)

    McCormick, Joshua L.; Quist, Michael C.; Schill, Daniel J.

    2013-01-01

    Chinook Salmon Oncorhynchus tshawytscha sport fisheries in the Columbia River basin are commonly monitored using roving creel survey designs and require precise, unbiased catch estimates. The objective of this study was to examine the relative bias and precision of total catch estimates using various sampling designs to estimate angling effort under the assumption that mean catch rate was known. We obtained information on angling populations based on direct visual observations of portions of Chinook Salmon fisheries in three Idaho river systems over a 23-d period. Based on the angling population, Monte Carlo simulations were used to evaluate the properties of effort and catch estimates for each sampling design. All sampling designs evaluated were relatively unbiased. Systematic random sampling (SYS) resulted in the most precise estimates. The SYS and simple random sampling designs had mean square error (MSE) estimates that were generally half of those observed with cluster sampling designs. The SYS design was more efficient (i.e., higher accuracy per unit cost) than a two-cluster design. Increasing the number of clusters available for sampling within a day decreased the MSE of estimates of daily angling effort, but the MSE of total catch estimates was variable depending on the fishery. The results of our simulations provide guidelines on the relative influence of sample sizes and sampling designs on parameters of interest in short-duration Chinook Salmon fisheries.

  2. Methods for Sampling and Measurement of Compressed Air Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Stroem, L

    1976-10-15

    In order to improve the technique for measuring oil and water entrained in a compressed air stream, a laboratory study has been made of some methods for sampling and measurement. For this purpose water or oil as artificial contaminants were injected in thin streams into a test loop, carrying dry compressed air. Sampling was performed in a vertical run, down-stream of the injection point. Wall attached liquid, coarse droplet flow, and fine droplet flow were sampled separately. The results were compared with two-phase flow theory and direct observation of liquid behaviour. In a study of sample transport through narrow tubes, it was observed that, below a certain liquid loading, the sample did not move, the liquid remaining stationary on the tubing wall. The basic analysis of the collected samples was made by gravimetric methods. Adsorption tubes were used with success to measure water vapour. A humidity meter with a sensor of the aluminium oxide type was found to be unreliable. Oil could be measured selectively by a flame ionization detector, the sample being pretreated in an evaporation- condensation unit

  3. Methods for Sampling and Measurement of Compressed Air Contaminants

    International Nuclear Information System (INIS)

    Stroem, L.

    1976-10-01

    In order to improve the technique for measuring oil and water entrained in a compressed air stream, a laboratory study has been made of some methods for sampling and measurement. For this purpose water or oil as artificial contaminants were injected in thin streams into a test loop, carrying dry compressed air. Sampling was performed in a vertical run, down-stream of the injection point. Wall attached liquid, coarse droplet flow, and fine droplet flow were sampled separately. The results were compared with two-phase flow theory and direct observation of liquid behaviour. In a study of sample transport through narrow tubes, it was observed that, below a certain liquid loading, the sample did not move, the liquid remaining stationary on the tubing wall. The basic analysis of the collected samples was made by gravimetric methods. Adsorption tubes were used with success to measure water vapour. A humidity meter with a sensor of the aluminium oxide type was found to be unreliable. Oil could be measured selectively by a flame ionization detector, the sample being pretreated in an evaporation- condensation unit

  4. Examination of Hydrate Formation Methods: Trying to Create Representative Samples

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, T.J.; Rees, E.V.L.; Nakagawa, S.; Kwon, T.-H.

    2011-04-01

    Forming representative gas hydrate-bearing laboratory samples is important so that the properties of these materials may be measured, while controlling the composition and other variables. Natural samples are rare, and have often experienced pressure and temperature changes that may affect the property to be measured [Waite et al., 2008]. Forming methane hydrate samples in the laboratory has been done a number of ways, each having advantages and disadvantages. The ice-to-hydrate method [Stern et al., 1996], contacts melting ice with methane at the appropriate pressure to form hydrate. The hydrate can then be crushed and mixed with mineral grains under controlled conditions, and then compacted to create laboratory samples of methane hydrate in a mineral medium. The hydrate in these samples will be part of the load-bearing frame of the medium. In the excess gas method [Handa and Stupin, 1992], water is distributed throughout a mineral medium (e.g. packed moist sand, drained sand, moistened silica gel, other porous media) and the mixture is brought to hydrate-stable conditions (chilled and pressurized with gas), allowing hydrate to form. This method typically produces grain-cementing hydrate from pendular water in sand [Waite et al., 2004]. In the dissolved gas method [Tohidi et al., 2002], water with sufficient dissolved guest molecules is brought to hydrate-stable conditions where hydrate forms. In the laboratory, this is can be done by pre-dissolving the gas of interest in water and then introducing it to the sample under the appropriate conditions. With this method, it is easier to form hydrate from more soluble gases such as carbon dioxide. It is thought that this method more closely simulates the way most natural gas hydrate has formed. Laboratory implementation, however, is difficult, and sample formation is prohibitively time consuming [Minagawa et al., 2005; Spangenberg and Kulenkampff, 2005]. In another version of this technique, a specified quantity of gas

  5. Measuring fertility through mobile‒phone based household surveys: Methods, data quality, and lessons learned from PMA2020 surveys

    Directory of Open Access Journals (Sweden)

    Yoonjoung Choi

    2018-05-01

    Full Text Available Background: PMA2020 is a survey platform with resident enumerators using mobile phones. Instead of collecting full birth history, total fertility rates (TFR have been measured with a limited number of questions on recent births. Employing new approaches provides opportunities to test and advance survey methods. Objective: This study aims to assess the quality of fertility data in PMA2020 surveys, focusing on bias introduced from the questionnaire and completeness and distribution of birth month and year, and to estimate TFR adjusted for identified data quality issues. Methods: To assess underestimation from the questionnaire, we simulated births that would be counted using the PMA2020 questionnaires compared to births identified from full birth history. We analyzed the latest Demographic and Health Surveys in ten countries where PMA2020 surveys have been implemented. We assessed the level of reporting completeness for birth month and year and heaping of birth month, analyzing 39 PMA2020 surveys. Finally, TFR were calculated and adjusted for biases introduced from the questionnaire and heaping in birth month. Results: Simple questions introduced minor bias from undercounting multiple births, which was expected and correctable. Meanwhile, incomplete reporting of birth month was relatively high, and the default value of January in data collection software systematically moved births with missing months out of the reference period. On average across the 39 surveys, TFR increased by 1.6Š and 2.4Š, adjusted for undercounted multiple births and heaping on January, respectively. Contribution: This study emphasizes the importance of enumerator training and provides critical insight in software programming in surveys using mobile technologies.

  6. Turbidity threshold sampling: Methods and instrumentation

    Science.gov (United States)

    Rand Eads; Jack Lewis

    2001-01-01

    Traditional methods for determining the frequency of suspended sediment sample collection often rely on measurements, such as water discharge, that are not well correlated to sediment concentration. Stream power is generally not a good predictor of sediment concentration for rivers that transport the bulk of their load as fines, due to the highly variable routing of...

  7. Solid phase microextraction headspace sampling of chemical warfare agent contaminated samples : method development for GC-MS analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jackson Lepage, C.R.; Hancock, J.R. [Defence Research and Development Canada, Medicine Hat, AB (Canada); Wyatt, H.D.M. [Regina Univ., SK (Canada)

    2004-07-01

    Defence R and D Canada-Suffield (DRDC-Suffield) is responsible for analyzing samples that are suspected to contain chemical warfare agents, either collected by the Canadian Forces or by first-responders in the event of a terrorist attack in Canada. The analytical techniques used to identify the composition of the samples include gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), Fourier-transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy. GC-MS and LC-MS generally require solvent extraction and reconcentration, thereby increasing sample handling. The authors examined analytical techniques which reduce or eliminate sample manipulation. In particular, this paper presented a screening method based on solid phase microextraction (SPME) headspace sampling and GC-MS analysis for chemical warfare agents such as mustard, sarin, soman, and cyclohexyl methylphosphonofluoridate in contaminated soil samples. SPME is a method which uses small adsorbent polymer coated silica fibers that trap vaporous or liquid analytes for GC or LC analysis. Collection efficiency can be increased by adjusting sampling time and temperature. This method was tested on two real-world samples, one from excavated chemical munitions and the second from a caustic decontamination mixture. 7 refs., 2 tabs., 3 figs.

  8. Modeling the Sensitivity of Field Surveys for Detection of Environmental DNA (eDNA.

    Directory of Open Access Journals (Sweden)

    Martin T Schultz

    Full Text Available The environmental DNA (eDNA method is the practice of collecting environmental samples and analyzing them for the presence of a genetic marker specific to a target species. Little is known about the sensitivity of the eDNA method. Sensitivity is the probability that the target marker will be detected if it is present in the water body. Methods and tools are needed to assess the sensitivity of sampling protocols, design eDNA surveys, and interpret survey results. In this study, the sensitivity of the eDNA method is modeled as a function of ambient target marker concentration. The model accounts for five steps of sample collection and analysis, including: 1 collection of a filtered water sample from the source; 2 extraction of DNA from the filter and isolation in a purified elution; 3 removal of aliquots from the elution for use in the polymerase chain reaction (PCR assay; 4 PCR; and 5 genetic sequencing. The model is applicable to any target species. For demonstration purposes, the model is parameterized for bighead carp (Hypophthalmichthys nobilis and silver carp (H. molitrix assuming sampling protocols used in the Chicago Area Waterway System (CAWS. Simulation results show that eDNA surveys have a high false negative rate at low concentrations of the genetic marker. This is attributed to processing of water samples and division of the extraction elution in preparation for the PCR assay. Increases in field survey sensitivity can be achieved by increasing sample volume, sample number, and PCR replicates. Increasing sample volume yields the greatest increase in sensitivity. It is recommended that investigators estimate and communicate the sensitivity of eDNA surveys to help facilitate interpretation of eDNA survey results. In the absence of such information, it is difficult to evaluate the results of surveys in which no water samples test positive for the target marker. It is also recommended that invasive species managers articulate concentration

  9. A Survey of Functional Behavior Assessment Methods Used by Behavior Analysts in Practice

    Science.gov (United States)

    Oliver, Anthony C.; Pratt, Leigh A.; Normand, Matthew P.

    2015-01-01

    To gather information about the functional behavior assessment (FBA) methods behavior analysts use in practice, we sent a web-based survey to 12,431 behavior analysts certified by the Behavior Analyst Certification Board. Ultimately, 724 surveys were returned, with the results suggesting that most respondents regularly use FBA methods, especially…

  10. What Are Probability Surveys used by the National Aquatic Resource Surveys?

    Science.gov (United States)

    The National Aquatic Resource Surveys (NARS) use probability-survey designs to assess the condition of the nation’s waters. In probability surveys (also known as sample-surveys or statistical surveys), sampling sites are selected randomly.

  11. Validation of method in instrumental NAA for food products sample

    International Nuclear Information System (INIS)

    Alfian; Siti Suprapti; Setyo Purwanto

    2010-01-01

    NAA is a method of testing that has not been standardized. To affirm and confirm that this method is valid. it must be done validation of the method with various sample standard reference materials. In this work. the validation is carried for food product samples using NIST SRM 1567a (wheat flour) and NIST SRM 1568a (rice flour). The results show that the validation method for testing nine elements (Al, K, Mg, Mn, Na, Ca, Fe, Se and Zn) in SRM 1567a and eight elements (Al, K, Mg, Mn, Na, Ca, Se and Zn ) in SRM 1568a pass the test of accuracy and precision. It can be conclude that this method has power to give valid result in determination element of the food products samples. (author)

  12. Validation of EIA sampling methods - bacterial and biochemical analysis

    Digital Repository Service at National Institute of Oceanography (India)

    Sheelu, G.; LokaBharathi, P.A.; Nair, S.; Raghukumar, C.; Mohandass, C.

    to temporal factors. Paired T-test between pre- and post-disturbance samples suggested that the above methods of sampling and variables like TC, protein and TOC could be used for monitoring disturbance....

  13. Empirically simulated study to compare and validate sampling methods used in aerial surveys of wildlife populations

    NARCIS (Netherlands)

    Khaemba, W.M.; Stein, A.; Rasch, D.; Leeuw, de J.; Georgiadis, N.

    2001-01-01

    This paper compares the distribution, sampling and estimation of abundance for two animal species in an African ecosystem by means of an intensive simulation of the sampling process under a geographical information system (GIS) environment. It focuses on systematic and random sampling designs,

  14. Protecting against both pregnancy and disease: predictors of dual method use among a sample of women.

    Science.gov (United States)

    Harvey, S Marie; Henderson, Jillian T; Branch, Meredith Roberts

    2004-01-01

    Although male condoms are the best form of protection against HIV/STDs, they are not the most effective method for preventing unintended pregnancy. Consequently, use of condoms and a highly effective contraceptive-referred to as dual use-is recommended as the optimal protection against both disease and pregnancy. However, little is known about the factors that promote dual use. This study examined associations of dual method use with women's background characteristics, intrapersonal factors, and relationship characteristics. Data are from a random sample of women selected from a large managed care organization in the Pacific Northwest. The analytic sample contained 371 women who completed a telephone survey and reported use of contraceptives in the past 3 months. Three mutually exclusive method use groups were constructed: effective contraceptive only (hormonal methods, intrauterine device, surgical sterilization) (59%), condom only (24%), and dual use (18%). Variables hypothesized to influence dual use were compared across the three groups in bivariate and multivariate analyses. Findings indicate that women who were younger, reported more than one sexual partner in the past year, and were highly motivated to avoid HIV/STDs--were more likely to use dual methods rather than condoms only or an effective contraceptive method. Women confident about using condoms without feeling embarrassed or breaking the sexual mood were more likely to use dual methods rather than a single effective method. Finally, women with confidence in their ability to use condoms correctly are more likely to rely solely on condoms. Policy and practice implications are discussed.

  15. An efficient method for sampling the essential subspace of proteins

    NARCIS (Netherlands)

    Amadei, A; Linssen, A.B M; de Groot, B.L.; van Aalten, D.M.F.; Berendsen, H.J.C.

    A method is presented for a more efficient sampling of the configurational space of proteins as compared to conventional sampling techniques such as molecular dynamics. The method is based on the large conformational changes in proteins revealed by the ''essential dynamics'' analysis. A form of

  16. Diagnosis of canine visceral leishmaniasis with radiolabelled probes: comparison of the kDNA PCR-hybridization with three molecular methods in different clinical samples

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Aline Leandra C.; Ferreira, Sidney A.; Carregal, Virginia M.; Andrade, Antero Silva R., E-mail: antero@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil). Lab. de Radiobiologia; Melo, Maria N., E-mail: melo@icb.ufmg.br [Departamento de Parasitologia. Instituto de Ciencias Biologicas. Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil)

    2011-07-01

    Leishmania (Leishmania) chagasi is responsible for visceral leishmaniasis (VL) in Brazil and the dog is the main domestic reservoir. Disease control is based on the elimination of infected animals and the use of a sensitive and specific diagnostic test is necessary. The Brazilian VL control program emphasizes serologic surveys, mainly using the enzyme-linked immunosorbent assay (ELISA) and the immunofluorescence antibody test (IFAT), followed by the elimination of the seropositive dogs. However, these techniques present limitations in terms of sensitivity and specificity. The Polymerase Chain Reaction (PCR) associated to hybridization with DNA probes labeled with {sup 32}P has been recognized as a valuable tool for Leishmania identification. In this study, the sensitivity of kDNA PCR hybridization method was compared with three other molecular methods: Internal Transcribed Spacer 1 Nested PCR (ITS-1nPCR), Leishmania nested PCR (LnPCR) and Seminested kDNA PCR (kDNA snPCR). The comparison was performed in different clinical specimens: conjunctival swab, skin, blood and bone marrow. A group of thirty symptomatic dogs, positive in the parasitological and serological tests, was used. When. The techniques targeting kDNA mini-circles (kDNA snPCR and KDNA PCR-hybridization) showed the worst result for blood samples. The KDNA-PCR hybridization showed the best sensitivity for conjunctival swab. By comparing the samples on the basis of positivity obtained by the sum of all methods, the blood showed the worst outcome (71/120).The bone marrow showed the highest positivity (106/120), followed by conjunctival swab (100/120) and skin (89/120). Since the bone marrow samples are unsuitable for routine epidemiological surveys, the conjunctival swab was recommended because it allows high sensitivity, especially when associated with kDNA PCR hybridization method, and is a noninvasive sampling method. (author)

  17. Diagnosis of canine visceral leishmaniasis with radiolabelled probes: comparison of the kDNA PCR-hybridization with three molecular methods in different clinical samples

    International Nuclear Information System (INIS)

    Ferreira, Aline Leandra C.; Ferreira, Sidney A.; Carregal, Virginia M.; Andrade, Antero Silva R.

    2011-01-01

    Leishmania (Leishmania) chagasi is responsible for visceral leishmaniasis (VL) in Brazil and the dog is the main domestic reservoir. Disease control is based on the elimination of infected animals and the use of a sensitive and specific diagnostic test is necessary. The Brazilian VL control program emphasizes serologic surveys, mainly using the enzyme-linked immunosorbent assay (ELISA) and the immunofluorescence antibody test (IFAT), followed by the elimination of the seropositive dogs. However, these techniques present limitations in terms of sensitivity and specificity. The Polymerase Chain Reaction (PCR) associated to hybridization with DNA probes labeled with 32 P has been recognized as a valuable tool for Leishmania identification. In this study, the sensitivity of kDNA PCR hybridization method was compared with three other molecular methods: Internal Transcribed Spacer 1 Nested PCR (ITS-1nPCR), Leishmania nested PCR (LnPCR) and Seminested kDNA PCR (kDNA snPCR). The comparison was performed in different clinical specimens: conjunctival swab, skin, blood and bone marrow. A group of thirty symptomatic dogs, positive in the parasitological and serological tests, was used. When. The techniques targeting kDNA mini-circles (kDNA snPCR and KDNA PCR-hybridization) showed the worst result for blood samples. The KDNA-PCR hybridization showed the best sensitivity for conjunctival swab. By comparing the samples on the basis of positivity obtained by the sum of all methods, the blood showed the worst outcome (71/120).The bone marrow showed the highest positivity (106/120), followed by conjunctival swab (100/120) and skin (89/120). Since the bone marrow samples are unsuitable for routine epidemiological surveys, the conjunctival swab was recommended because it allows high sensitivity, especially when associated with kDNA PCR hybridization method, and is a noninvasive sampling method. (author)

  18. Proper survey methods for research of aquatic plant ecology and management

    Science.gov (United States)

    Proper survey methods are essential for objective, quantitative assessment of the distribution and abundance of aquatic plants as part of research and demonstration efforts. For research, the use of the appropriate method is an essential part of the scientific method, to ensure that the experimenta...

  19. Development and Psychometric Evaluation of the HPV Clinical Trial Survey for Parents (CTSP-HPV) Using Traditional Survey Development Methods and Community Engagement Principles.

    Science.gov (United States)

    Cunningham, Jennifer; Wallston, Kenneth A; Wilkins, Consuelo H; Hull, Pamela C; Miller, Stephania T

    2015-12-01

    This study describes the development and psychometric evaluation of HPV Clinical Trial Survey for Parents with Children Aged 9 to 15 (CTSP-HPV) using traditional instrument development methods and community engagement principles. An expert panel and parental input informed survey content and parents recommended study design changes (e.g., flyer wording). A convenience sample of 256 parents completed the final survey measuring parental willingness to consent to HPV clinical trial (CT) participation and other factors hypothesized to influence willingness (e.g., HPV vaccine benefits). Cronbach's a, Spearman correlations, and multiple linear regression were used to estimate internal consistency, convergent and discriminant validity, and predictively validity, respectively. Internal reliability was confirmed for all scales (a ≥ 0.70.). Parental willingness was positively associated (p < 0.05) with trust in medical researchers, adolescent CT knowledge, HPV vaccine benefits, advantages of adolescent CTs (r range 0.33-0.42), supporting convergent validity. Moderate discriminant construct validity was also demonstrated. Regression results indicate reasonable predictive validity with the six scales accounting for 31% of the variance in parents' willingness. This instrument can inform interventions based on factors that influence parental willingness, which may lead to the eventual increase in trial participation. Further psychometric testing is warranted. © 2015 Wiley Periodicals, Inc.

  20. Measuring larval nematode contamination on cattle pastures: Comparing two herbage sampling methods.

    Science.gov (United States)

    Verschave, S H; Levecke, B; Duchateau, L; Vercruysse, J; Charlier, J

    2015-06-15

    Assessing levels of pasture larval contamination is frequently used to study the population dynamics of the free-living stages of parasitic nematodes of livestock. Direct quantification of infective larvae (L3) on herbage is the most applied method to measure pasture larval contamination. However, herbage collection remains labour intensive and there is a lack of studies addressing the variation induced by the sampling method and the required sample size. The aim of this study was (1) to compare two different sampling methods in terms of pasture larval count results and time required to sample, (2) to assess the amount of variation in larval counts at the level of sample plot, pasture and season, respectively and (3) to calculate the required sample size to assess pasture larval contamination with a predefined precision using random plots across pasture. Eight young stock pastures of different commercial dairy herds were sampled in three consecutive seasons during the grazing season (spring, summer and autumn). On each pasture, herbage samples were collected through both a double-crossed W-transect with samples taken every 10 steps (method 1) and four random located plots of 0.16 m(2) with collection of all herbage within the plot (method 2). The average (± standard deviation (SD)) pasture larval contamination using sampling methods 1 and 2 was 325 (± 479) and 305 (± 444)L3/kg dry herbage (DH), respectively. Large discrepancies in pasture larval counts of the same pasture and season were often seen between methods, but no significant difference (P = 0.38) in larval counts between methods was found. Less time was required to collect samples with method 2. This difference in collection time between methods was most pronounced for pastures with a surface area larger than 1 ha. The variation in pasture larval counts from samples generated by random plot sampling was mainly due to the repeated measurements on the same pasture in the same season (residual variance

  1. Identification of continuous-time systems from samples of input ...

    Indian Academy of Sciences (India)

    Abstract. This paper presents an introductory survey of the methods that have been developed for identification of continuous-time systems from samples of input±output data. The two basic approaches may be described as (i) the indirect method, where first a discrete-time model is estimated from the sampled data and then ...

  2. THE CHANDRA COSMOS-LEGACY SURVEY: THE z > 3 SAMPLE

    Energy Technology Data Exchange (ETDEWEB)

    Marchesi, S.; Civano, F.; Urry, C. M. [Yale Center for Astronomy and Astrophysics, 260 Whitney Avenue, New Haven, CT 06520 (United States); Salvato, M. [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, D-85748 Garching bei München (Germany); Shankar, F. [Department of Physics and Astronomy, University of Southampton, Highfield, SO17 1BJ (United Kingdom); Comastri, A.; Lanzuisi, G.; Vignali, C.; Zamorani, G.; Brusa, M.; Gilli, R. [INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna (Italy); Elvis, M. [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Trakhtenbrot, B.; Schawinski, K. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Allevato, V. [Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2a, FI-00014 Helsinki (Finland); Fiore, F. [INAF–Osservatorio Astronomico di Roma, via di Frascati 33, I-00040 Monte Porzio Catone (Italy); Griffiths, R. [Physics and Astronomy Department, Natural Sciences Division, University of Hawaii at Hilo, 200 W. Kawili Street, Hilo, HI 96720 (United States); Hasinger, G. [Institute for Astronomy, 2680 Woodlawn Drive, University of Hawaii, Honolulu, HI 96822 (United States); Miyaji, T. [Instituto de Astronomía sede Ensenada, Universidad Nacional Autónoma de México, Km. 103, Carret. Tijunana-Ensenada, Ensenada, BC (Mexico); Treister, E. [Universidad de Concepción, Departamento de Astronomía, Casilla 160-C, Concepción (Chile)

    2016-08-20

    We present the largest high-redshift (3 < z < 6.85) sample of X-ray-selected active galactic nuclei (AGNs) on a contiguous field, using sources detected in the Chandra COSMOS-Legacy survey. The sample contains 174 sources, 87 with spectroscopic redshift and the other 87 with photometric redshift (z {sub phot}). In this work, we treat z {sub phot} as a probability-weighted sum of contributions, adding to our sample the contribution of sources with z {sub phot} < 3 but z {sub phot} probability distribution >0 at z > 3. We compute the number counts in the observed 0.5–2 keV band, finding a decline in the number of sources at z > 3 and constraining phenomenological models of the X-ray background. We compute the AGN space density at z > 3 in two different luminosity bins. At higher luminosities (log L (2–10 keV) > 44.1 erg s{sup −1}), the space density declines exponentially, dropping by a factor of ∼20 from z ∼ 3 to z ∼ 6. The observed decline is ∼80% steeper at lower luminosities (43.55 erg s{sup −1} < logL(2–10 keV) < 44.1 erg s{sup −1}) from z ∼ 3 to z ∼ 4.5. We study the space density evolution dividing our sample into optically classified Type 1 and Type 2 AGNs. At log L (2–10 keV) > 44.1 erg s{sup −1}, unobscured and obscured objects may have different evolution with redshift, with the obscured component being three times higher at z ∼ 5. Finally, we compare our space density with predictions of quasar activation merger models, whose calibration is based on optically luminous AGNs. These models significantly overpredict the number of expected AGNs at log L (2–10 keV) > 44.1 erg s{sup −1} with respect to our data.

  3. Clustering Methods with Qualitative Data: a Mixed-Methods Approach for Prevention Research with Small Samples.

    Science.gov (United States)

    Henry, David; Dymnicki, Allison B; Mohatt, Nathaniel; Allen, James; Kelly, James G

    2015-10-01

    Qualitative methods potentially add depth to prevention research but can produce large amounts of complex data even with small samples. Studies conducted with culturally distinct samples often produce voluminous qualitative data but may lack sufficient sample sizes for sophisticated quantitative analysis. Currently lacking in mixed-methods research are methods allowing for more fully integrating qualitative and quantitative analysis techniques. Cluster analysis can be applied to coded qualitative data to clarify the findings of prevention studies by aiding efforts to reveal such things as the motives of participants for their actions and the reasons behind counterintuitive findings. By clustering groups of participants with similar profiles of codes in a quantitative analysis, cluster analysis can serve as a key component in mixed-methods research. This article reports two studies. In the first study, we conduct simulations to test the accuracy of cluster assignment using three different clustering methods with binary data as produced when coding qualitative interviews. Results indicated that hierarchical clustering, K-means clustering, and latent class analysis produced similar levels of accuracy with binary data and that the accuracy of these methods did not decrease with samples as small as 50. Whereas the first study explores the feasibility of using common clustering methods with binary data, the second study provides a "real-world" example using data from a qualitative study of community leadership connected with a drug abuse prevention project. We discuss the implications of this approach for conducting prevention research, especially with small samples and culturally distinct communities.

  4. Clustering Methods with Qualitative Data: A Mixed Methods Approach for Prevention Research with Small Samples

    Science.gov (United States)

    Henry, David; Dymnicki, Allison B.; Mohatt, Nathaniel; Allen, James; Kelly, James G.

    2016-01-01

    Qualitative methods potentially add depth to prevention research, but can produce large amounts of complex data even with small samples. Studies conducted with culturally distinct samples often produce voluminous qualitative data, but may lack sufficient sample sizes for sophisticated quantitative analysis. Currently lacking in mixed methods research are methods allowing for more fully integrating qualitative and quantitative analysis techniques. Cluster analysis can be applied to coded qualitative data to clarify the findings of prevention studies by aiding efforts to reveal such things as the motives of participants for their actions and the reasons behind counterintuitive findings. By clustering groups of participants with similar profiles of codes in a quantitative analysis, cluster analysis can serve as a key component in mixed methods research. This article reports two studies. In the first study, we conduct simulations to test the accuracy of cluster assignment using three different clustering methods with binary data as produced when coding qualitative interviews. Results indicated that hierarchical clustering, K-Means clustering, and latent class analysis produced similar levels of accuracy with binary data, and that the accuracy of these methods did not decrease with samples as small as 50. Whereas the first study explores the feasibility of using common clustering methods with binary data, the second study provides a “real-world” example using data from a qualitative study of community leadership connected with a drug abuse prevention project. We discuss the implications of this approach for conducting prevention research, especially with small samples and culturally distinct communities. PMID:25946969

  5. Soybean yield modeling using bootstrap methods for small samples

    Energy Technology Data Exchange (ETDEWEB)

    Dalposso, G.A.; Uribe-Opazo, M.A.; Johann, J.A.

    2016-11-01

    One of the problems that occur when working with regression models is regarding the sample size; once the statistical methods used in inferential analyzes are asymptotic if the sample is small the analysis may be compromised because the estimates will be biased. An alternative is to use the bootstrap methodology, which in its non-parametric version does not need to guess or know the probability distribution that generated the original sample. In this work we used a set of soybean yield data and physical and chemical soil properties formed with fewer samples to determine a multiple linear regression model. Bootstrap methods were used for variable selection, identification of influential points and for determination of confidence intervals of the model parameters. The results showed that the bootstrap methods enabled us to select the physical and chemical soil properties, which were significant in the construction of the soybean yield regression model, construct the confidence intervals of the parameters and identify the points that had great influence on the estimated parameters. (Author)

  6. Research and application of soil-mercury-surveys method for locating uranium

    International Nuclear Information System (INIS)

    You Yunfei; Lu Shili; Jiao Zongrun

    1995-06-01

    Soil-Hg-Surveys method for locating uranium ore was presented. Soil-sampler of drilling bottom, the ability of surveying the deep uranium orebodies was raised by using this method. Application of minicomputer technology to pyrolytic-Hg-analysis raises the degree of automation and precision of the analysis. Application condition of optimum is Hg content of orebodies >1 x 10 -6 . Locating deep is about 100 m. The forecast of uranium orebodies achieved success in two unknown section that are 534 and 510 mining area, therefore two little size deposits expanded into middle size deposits. This method is as well applicable to locating gold, silver, copper, lead zinc and oil-gas natural resource and so on. (8 figs., 3 tabs.)

  7. Radiochemistry methods in DOE Methods for Evaluating Environmental and Waste Management Samples: Addressing new challenges

    International Nuclear Information System (INIS)

    Fadeff, S.K.; Goheen, S.C.; Riley, R.G.

    1994-01-01

    Radiochemistry methods in Department of Energy Methods for Evaluating Environmental and Waste Management Samples (DOE Methods) add to the repertoire of other standard methods in support of U.S. Department of Energy environmental restoration and waste management (DOE/EM) radiochemical characterization activities. Current standard sources of radiochemistry methods are not always applicable for evaluating DOE/EM samples. Examples of current sources include those provided by the US Environmental Protection Agency, the American Society for Testing and Materials, Standard Methods for the Examination of Water and Wastewater, and Environmental Measurements Laboratory Procedures Manual (HASL-300). The applicability of these methods is generally limited to specific matrices (usually water), low-level radioactive samples, and a limited number of analytes. DOE Methods complements these current standard methods by addressing the complexities of EM characterization needs. The process for determining DOE/EM radiochemistry characterization needs is discussed. In this context of DOE/EM needs, the applicability of other sources of standard radiochemistry methods is defined, and gaps in methodology are identified. Current methods in DOE Methods and the EM characterization needs they address are discussed. Sources of new methods and the methods incorporation process are discussed. The means for individuals to participate in (1) identification of DOE/EM needs, (2) the methods incorporation process, and (3) submission of new methods are identified

  8. A comprehensive comparison of perpendicular distance sampling methods for sampling downed coarse woody debris

    Science.gov (United States)

    Jeffrey H. Gove; Mark J. Ducey; Harry T. Valentine; Michael S. Williams

    2013-01-01

    Many new methods for sampling down coarse woody debris have been proposed in the last dozen or so years. One of the most promising in terms of field application, perpendicular distance sampling (PDS), has several variants that have been progressively introduced in the literature. In this study, we provide an overview of the different PDS variants and comprehensive...

  9. Geochemical reanalysis of historical U.S. Geological Survey sediment samples from the Haines area, Juneau and Skagway quadrangles, southeast Alaska

    Science.gov (United States)

    Werdon, Melanie B.; Granitto, Matthew; Azain, Jaime S.

    2015-01-01

    The State of Alaska’s Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska’s statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. As part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential. The USGS is also undertaking SCM-related geologic studies in Alaska through the federally funded Alaska Critical Minerals cooperative project. DGGS and USGS share the goal of evaluating Alaska’s strategic and critical minerals potential and together created a Letter of Agreement (signed December 2012) and a supplementary Technical Assistance Agreement (#14CMTAA143458) to facilitate the two agencies’ cooperative work. Under these agreements, DGGS contracted the USGS in Denver to reanalyze historical USGS sediment samples from Alaska. For this report, DGGS funded reanalysis of 212 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from the Chilkat, Klehini, Tsirku, and Takhin river drainages, as well as smaller drainages flowing into Chilkat and Chilkoot Inlets near Haines, Skagway Quadrangle, Southeast Alaska. Additionally some samples were also chosen from the Juneau gold belt, Juneau Quadrangle, Southeast Alaska (fig. 1). The USGS was responsible for sample retrieval from the National Geochemical Sample Archive (NGSA) in Denver, Colorado through the final quality assurance/quality control (QA/QC) of the geochemical

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

    Science.gov (United States)

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

    2017-11-01

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

  11. Shear Strength of Remoulding Clay Samples Using Different Methods of Moulding

    Science.gov (United States)

    Norhaliza, W.; Ismail, B.; Azhar, A. T. S.; Nurul, N. J.

    2016-07-01

    Shear strength for clay soil was required to determine the soil stability. Clay was known as a soil with complex natural formations and very difficult to obtain undisturbed samples at the site. The aim of this paper was to determine the unconfined shear strength of remoulded clay on different methods in moulding samples which were proctor compaction, hand operated soil compacter and miniature mould methods. All the samples were remoulded with the same optimum moisture content (OMC) and density that were 18% and 1880 kg/m3 respectively. The unconfined shear strength results of remoulding clay soils for proctor compaction method was 289.56kPa with the strain 4.8%, hand operated method was 261.66kPa with the strain 4.4% and miniature mould method was 247.52kPa with the strain 3.9%. Based on the proctor compaction method, the reduction percentage of unconfined shear strength of remoulded clay soil of hand operated method was 9.66%, and for miniature mould method was 14.52%. Thus, because there was no significant difference of reduction percentage of unconfined shear strength between three different methods, so it can be concluded that remoulding clay by hand operated method and miniature mould method were accepted and suggested to perform remoulding clay samples by other future researcher. However for comparison, the hand operated method was more suitable to form remoulded clay sample in term of easiness, saving time and less energy for unconfined shear strength determination purposes.

  12. A multi-dimensional sampling method for locating small scatterers

    International Nuclear Information System (INIS)

    Song, Rencheng; Zhong, Yu; Chen, Xudong

    2012-01-01

    A multiple signal classification (MUSIC)-like multi-dimensional sampling method (MDSM) is introduced to locate small three-dimensional scatterers using electromagnetic waves. The indicator is built with the most stable part of signal subspace of the multi-static response matrix on a set of combinatorial sampling nodes inside the domain of interest. It has two main advantages compared to the conventional MUSIC methods. First, the MDSM is more robust against noise. Second, it can work with a single incidence even for multi-scatterers. Numerical simulations are presented to show the good performance of the proposed method. (paper)

  13. Geochemical reanalysis of historical U.S. Geological Survey sediment samples from the Kougarok area, Bendeleben and Teller quadrangles, Seward Peninsula, Alaska

    Science.gov (United States)

    Werdon, Melanie B.; Granitto, Matthew; Azain, Jaime S.

    2015-01-01

    The State of Alaska’s Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska’s statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. As part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential. The USGS is also undertaking SCM-related geologic studies in Alaska through the federally funded Alaska Critical Minerals cooperative project. DGGS and USGS share the goal of evaluating Alaska’s strategic and critical minerals potential and together created a Letter of Agreement (signed December 2012) and a supplementary Technical Assistance Agreement (#14CMTAA143458) to facilitate the two agencies’ cooperative work. Under these agreements, DGGS contracted the USGS in Denver to reanalyze historical USGS sediment samples from Alaska. For this report, DGGS funded reanalysis of 302 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from the Kougarok River drainage as well as smaller adjacent drainages in the Bendeleben and Teller quadrangles, Seward Peninsula, Alaska (fig. 1). The USGS was responsible for sample retrieval from the National Geochemical Sample Archive (NGSA) in Denver, Colorado through the final quality assurance/quality control (QA/QC) of the geochemical analyses obtained through the USGS contract lab. The new geochemical data are published in this report as a coauthored DGGS report, and will be incorporated

  14. Methods for Characterisation of unknown Suspect Radioactive Samples

    International Nuclear Information System (INIS)

    Sahagia, M.; Grigorescu, E.L.; Luca, A.; Razdolescu, A.C.; Ivan, C.

    2001-01-01

    Full text: The paper presents various identification and measurement methods, used for the expertise of a wide variety of suspect radioactive materials, whose circulation was not legally stated. The main types of examined samples were: radioactive sources, illegally trafficked; suspect radioactive materials or radioactively contaminated devices; uranium tablets; fire detectors containing 241 Am sources; osmium samples containing radioactive 185 Os or enriched 187 Os. The types of analyses and determination methods were as follows: the chemical composition was determined by using identification reagents or by neutron activation analysis; the radionuclide composition was determined by using gamma-ray spectrometry; the activity and particle emission rates were determined by using calibrated radiometric equipment; the absorbed dose rate at the wall of all types of containers and samples was determined by using calibrated dose ratemeters. The radiation exposure risk for population, due to these radioactive materials, was evaluated for every case. (author)

  15. Multielement methods of atomic fluorescence analysis of enviromental samples

    International Nuclear Information System (INIS)

    Rigin, V.I.

    1985-01-01

    A multielement method of atomic fluorescence analysis of environmental samples based on sample decomposition by autoclave fluorination and gas-phase atomization of volatile compounds in inductive araon plasma using a nondispersive polychromator is suggested. Detection limits of some elements (Be, Sr, Cd, V, Mo, Te, Ru etc.) for different sample forms introduced in to an analyzer are given

  16. A DOE manual: DOE Methods for Evaluating Environmental and Waste Management Samples

    International Nuclear Information System (INIS)

    Goheen, S.C.; McCulloch, M.; Riley, R.G.

    1994-01-01

    Waste Management inherently requires knowledge of the waste's chemical composition. The waste can often be analyzed by established methods; however, if the samples are radioactive, or are plagued by other complications, established methods may not be feasible. The US Department of Energy (DOE) has been faced with managing some waste types that are not amenable to standard or available methods, so new or modified sampling and analysis methods are required. These methods are incorporated into DOE Methods for Evaluating Environmental and Waste Management Samples (DOE Methods), which is a guidance/methods document for sampling and analysis activities in support of DOE sites. It is a document generated by consensus of the DOE laboratory staff and is intended to fill the gap within existing guidance documents (e. g., the Environmental Protection Agency's (EPA's) Test Methods for Evaluating Solid Waste, SW-846), which apply to low-level or non-radioactive samples. DOE Methods fills the gap by including methods that take into account the complexities of DOE site matrices. The most recent update, distributed in October 1993, contained quality assurance (QA), quality control (QC), safety, sampling, organic analysis, inorganic analysis, and radioanalytical guidance as well as 29 methods. The next update, which will be distributed in April 1994, will contain 40 methods and will therefore have greater applicability. All new methods are either peer reviewed or labeled ''draft'' methods. Draft methods were added to speed the release of methods to field personnel

  17. A within-sample investigation of test–retest reliability in choice experiment surveys with real economic incentives

    DEFF Research Database (Denmark)

    Mørkbak, Morten Raun; Olsen, Søren Bøye

    2015-01-01

    In this paper, we investigate the level of agreement between respondents' choices in identical choice sets in a test-retest choice experiment for a market good with real economic incentives, thus investigating whether the incentivised CE method can be reliable and stable over time. Besides...... comparing choices, we also test for differences in preferences and error variance when a sample of respondents is given the exact same questionnaire twice, with a time lag of 2 weeks in between. Finally, we examine potential reasons and covariates explaining the level of agreement in choices across the 2...... weeks. Across four different tests, we find very good agreement between the two choice experiments - both with respect to overall choices and with respect to preferences. Furthermore, error variances do not differ significantly between the two surveys. The results also show that the larger the utility...

  18. Optimal Allocation of Sampling Effort in Depletion Surveys

    Science.gov (United States)

    We consider the problem of designing a depletion or removal survey as part of estimating animal abundance for populations with imperfect capture or detection rates. In a depletion survey, animals are captured from a given area, counted, and withheld from the population. This proc...

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

    International Nuclear Information System (INIS)

    Sansoni, B.; Iyengar, V.

    1978-05-01

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

  20. [Progress in sample preparation and analytical methods for trace polar small molecules in complex samples].

    Science.gov (United States)

    Zhang, Qianchun; Luo, Xialin; Li, Gongke; Xiao, Xiaohua

    2015-09-01

    Small polar molecules such as nucleosides, amines, amino acids are important analytes in biological, food, environmental, and other fields. It is necessary to develop efficient sample preparation and sensitive analytical methods for rapid analysis of these polar small molecules in complex matrices. Some typical materials in sample preparation, including silica, polymer, carbon, boric acid and so on, are introduced in this paper. Meanwhile, the applications and developments of analytical methods of polar small molecules, such as reversed-phase liquid chromatography, hydrophilic interaction chromatography, etc., are also reviewed.

  1. Practical Bias Correction in Aerial Surveys of Large Mammals: Validation of Hybrid Double-Observer with Sightability Method against Known Abundance of Feral Horse (Equus caballus) Populations.

    Science.gov (United States)

    Lubow, Bruce C; Ransom, Jason I

    2016-01-01

    Reliably estimating wildlife abundance is fundamental to effective management. Aerial surveys are one of the only spatially robust tools for estimating large mammal populations, but statistical sampling methods are required to address detection biases that affect accuracy and precision of the estimates. Although various methods for correcting aerial survey bias are employed on large mammal species around the world, these have rarely been rigorously validated. Several populations of feral horses (Equus caballus) in the western United States have been intensively studied, resulting in identification of all unique individuals. This provided a rare opportunity to test aerial survey bias correction on populations of known abundance. We hypothesized that a hybrid method combining simultaneous double-observer and sightability bias correction techniques would accurately estimate abundance. We validated this integrated technique on populations of known size and also on a pair of surveys before and after a known number was removed. Our analysis identified several covariates across the surveys that explained and corrected biases in the estimates. All six tests on known populations produced estimates with deviations from the known value ranging from -8.5% to +13.7% and corrected by our statistical models. Our results validate the hybrid method, highlight its potentially broad applicability, identify some limitations, and provide insight and guidance for improving survey designs.

  2. Rapid Active Sampling Surveys as a Tool to Evaluate Factors Associated with Acute Gastroenteritis and Norovirus Infection among Children in Rural Guatemala.

    Science.gov (United States)

    Olson, Daniel; Lamb, Molly M; Lopez, Maria R; Paniagua-Avila, Maria A; Zacarias, Alma; Samayoa-Reyes, Gabriela; Cordon-Rosales, Celia; Asturias, Edwin J

    2017-09-01

    We examined burden and factors associated with norovirus (NoV) acute gastroenteritis (AGE) among children in rural Guatemala. Children age 6 weeks to 17 years were enrolled into three AGE surveillance groups, using two-stage cluster sampling: a prospective participatory syndromic surveillance (PSS) cohort and two cross-sectional rapid active sampling (RAS) surveys, conducted from April 2015 to February 2016. Epidemiologic and NoV testing data were used to identify factors associated with NoV infection, AGE, and NoV+ AGE. The three cross-sectional surveys (PSS enrollment visit, RAS Survey 1, and RAS Survey 2) enrolled 1,239 children, who reported 134 (11%) AGE cases, with 20% of AGE and 11% of non-AGE samples positive for NoV. Adjusted analyses identified several modifiable factors associated with AGE and NoV infection. The cross-sectional RAS surveys were practical and cost-effective in identifying population-level risk factors for AGE and NoV, supporting their use as a tool to direct limited public health resources toward high-risk populations.

  3. Simplified pupal surveys of Aedes aegypti (L.) for entomologic surveillance and dengue control.

    Science.gov (United States)

    Barrera, Roberto

    2009-07-01

    Pupal surveys of Aedes aegypti (L.) are useful indicators of risk for dengue transmission, although sample sizes for reliable estimations can be large. This study explores two methods for making pupal surveys more practical yet reliable and used data from 10 pupal surveys conducted in Puerto Rico during 2004-2008. The number of pupae per person for each sampling followed a negative binomial distribution, thus showing aggregation. One method found a common aggregation parameter (k) for the negative binomial distribution, a finding that enabled the application of a sequential sampling method requiring few samples to determine whether the number of pupae/person was above a vector density threshold for dengue transmission. A second approach used the finding that the mean number of pupae/person is correlated with the proportion of pupa-infested households and calculated equivalent threshold proportions of pupa-positive households. A sequential sampling program was also developed for this method to determine whether observed proportions of infested households were above threshold levels. These methods can be used to validate entomological thresholds for dengue transmission.

  4. Short assessment of the Big Five: robust across survey methods except telephone interviewing

    OpenAIRE

    Lang, Frieder R.; John, Dennis; Lüdtke, Oliver; Schupp, Jürgen; Wagner, Gert G.

    2011-01-01

    We examined measurement invariance and age-related robustness of a short 15-item Big Five Inventory (BFI–S) of personality dimensions, which is well suited for applications in large-scale multidisciplinary surveys. The BFI–S was assessed in three different interviewing conditions: computer-assisted or paper-assisted face-to-face interviewing, computer-assisted telephone interviewing, and a self-administered questionnaire. Randomized probability samples from a large-scale German panel survey a...

  5. Methods of sampling airborne fungi in working environments of waste treatment facilities.

    Science.gov (United States)

    Černá, Kristýna; Wittlingerová, Zdeňka; Zimová, Magdaléna; Janovský, Zdeněk

    2016-01-01

    The objective of the present study was to evaluate and compare the efficiency of a filter based sampling method and a high volume sampling method for sampling airborne culturable fungi present in waste sorting facilities. Membrane filters method was compared with surface air system method. The selected sampling methods were modified and tested in 2 plastic waste sorting facilities. The total number of colony-forming units (CFU)/m3 of airborne fungi was dependent on the type of sampling device, on the time of sampling, which was carried out every hour from the beginning of the work shift, and on the type of cultivation medium (p airborne fungi ranged 2×102-1.7×106 CFU/m3 when using the membrane filters (MF) method, and 3×102-6.4×104 CFU/m3 when using the surface air system (SAS) method. Both methods showed comparable sensitivity to the fluctuations of the concentrations of airborne fungi during the work shifts. The SAS method is adequate for a fast indicative determination of concentration of airborne fungi. The MF method is suitable for thorough assessment of working environment contamination by airborne fungi. Therefore we recommend the MF method for the implementation of a uniform standard methodology of airborne fungi sampling in working environments of waste treatment facilities. This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.

  6. Survey of Technetium Analytical Production Methods Supporting Hanford Nuclear Materials Processing

    International Nuclear Information System (INIS)

    TROYER, G.L.

    1999-01-01

    This document provides a historical survey of analytical methods used for measuring 99 Tc in nuclear fuel reprocessing materials and wastes at Hanford. Method challenges including special sludge matrices tested are discussed. Special problems and recommendations are presented

  7. [Data validation methods and discussion on Chinese materia medica resource survey].

    Science.gov (United States)

    Zhang, Yue; Ma, Wei-Feng; Zhang, Xiao-Bo; Zhu, Shou-Dong; Guo, Lan-Ping; Wang, Xing-Xing

    2013-07-01

    From the beginning of the fourth national survey of the Chinese materia medica resources, there were 22 provinces have conducted pilots. The survey teams have reported immense data, it put forward the very high request to the database system construction. In order to ensure the quality, it is necessary to check and validate the data in database system. Data validation is important methods to ensure the validity, integrity and accuracy of census data. This paper comprehensively introduce the data validation system of the fourth national survey of the Chinese materia medica resources database system, and further improve the design idea and programs of data validation. The purpose of this study is to promote the survey work smoothly.

  8. Spread of Traditional Medicines in India: Results of National Sample Survey Organization's Perception Survey on Use of AYUSH.

    Science.gov (United States)

    Srinivasan, R; Sugumar, V Raji

    2015-10-04

    For the first time, we have a comprehensive database on usage of AYUSH (acronym for Ayurveda, naturopathy and Yoga, Unani, Siddha, and Homeopathy) in India at the household level. This article aims at exploring the spread of the traditional medical systems in India and the perceptions of people on the access and effectiveness of these medical systems using this database. The article uses the unit level data purchased from the National Sample Survey Organization, New Delhi. Household is the basic unit of survey and the data are the collective opinion of the household. This survey shows that less than 30% of Indian households use the traditional medical systems. There is also a regional pattern in the usage of particular type of traditional medicine, reflecting the regional aspects of the development of such medical systems. The strong faith in AYUSH is the main reason for its usage; lack of need for AYUSH and lack of awareness about AYUSH are the main reasons for not using it. With regard to source of medicines in the traditional medical systems, home is the main source in the Indian medical system and private sector is the main source in Homeopathy. This shows that there is need for creating awareness and improving access to traditional medical systems in India. By and large, the users of AYUSH are also convinced about the effectiveness of these traditional medicines. © The Author(s) 2015.

  9. Single- versus multiple-sample method to measure glomerular filtration rate.

    Science.gov (United States)

    Delanaye, Pierre; Flamant, Martin; Dubourg, Laurence; Vidal-Petiot, Emmanuelle; Lemoine, Sandrine; Cavalier, Etienne; Schaeffner, Elke; Ebert, Natalie; Pottel, Hans

    2018-01-08

    There are many different ways to measure glomerular filtration rate (GFR) using various exogenous filtration markers, each having their own strengths and limitations. However, not only the marker, but also the methodology may vary in many ways, including the use of urinary or plasma clearance, and, in the case of plasma clearance, the number of time points used to calculate the area under the concentration-time curve, ranging from only one (Jacobsson method) to eight (or more) blood samples. We collected the results obtained from 5106 plasma clearances (iohexol or 51Cr-ethylenediaminetetraacetic acid (EDTA)) using three to four time points, allowing GFR calculation using the slope-intercept method and the Bröchner-Mortensen correction. For each time point, the Jacobsson formula was applied to obtain the single-sample GFR. We used Bland-Altman plots to determine the accuracy of the Jacobsson method at each time point. The single-sample method showed within 10% concordances with the multiple-sample method of 66.4%, 83.6%, 91.4% and 96.0% at the time points 120, 180, 240 and ≥300 min, respectively. Concordance was poorer at lower GFR levels, and this trend is in parallel with increasing age. Results were similar in males and females. Some discordance was found in the obese subjects. Single-sample GFR is highly concordant with a multiple-sample strategy, except in the low GFR range (<30 mL/min). © The Author 2018. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  10. International survey blauwe wijting. Elke seconde een sample

    NARCIS (Netherlands)

    Faessler, S.M.M.

    2011-01-01

    IJMuiden- in 2011 wordt voor het eerst de jaarlijkse blauwe wijting survey gecoördineerd door Schascha Fässler, geboren Zwitser en sinds 2009 als 'fisheries acoustics' scientist' werkzaam bij IMARES in IJmuiden. In onderstaand artikel gaat Fässler nader in op acoustics in het algemeen en de survey

  11. Analytical methods manual for the Mineral Resource Surveys Program, U.S. Geological Survey

    Science.gov (United States)

    Arbogast, Belinda F.

    1996-01-01

    The analytical methods validated by the Mineral Resource Surveys Program, Geologic Division, is the subject of this manual. This edition replaces the methods portion of Open-File Report 90-668 published in 1990. Newer methods may be used which have been approved by the quality assurance (QA) project and are on file with the QA coordinator.This manual is intended primarily for use by laboratory scientists; this manual can also assist laboratory users to evaluate the data they receive. The analytical methods are written in a step by step approach so that they may be used as a training tool and provide detailed documentation of the procedures for quality assurance. A "Catalog of Services" is available for customer (submitter) use with brief listings of:the element(s)/species determined,method of determination,reference to cite,contact person,summary of the technique,and analyte concentration range.For a copy please contact the Branch office at (303) 236-1800 or fax (303) 236-3200.

  12. Sampling and analysis methods for geothermal fluids and gases

    Energy Technology Data Exchange (ETDEWEB)

    Shannon, D. W.

    1978-01-01

    The data obtained for the first round robin sample collected at Mesa 6-2 wellhead, East Mesa Test Site, Imperial Valley are summarized. Test results are listed by method used for cross reference to the analytic methods section. Results obtained for radioactive isotopes present in the brine sample are tabulated. The data obtained for the second round robin sample collected from the Woolsey No. 1 first stage flash unit, San Diego Gas and Electric Niland Test Facility are presented in the same manner. Lists of the participants of the two round robins are given. Data from miscellaneous analyses are included. Summaries of values derived from the round robin raw data are presented. (MHR)

  13. Effects of phone versus mail survey methods on the measurement of health-related quality of life and emotional and behavioural problems in adolescents.

    Science.gov (United States)

    Erhart, Michael; Wetzel, Ralf M; Krügel, André; Ravens-Sieberer, Ulrike

    2009-12-30

    Telephone interviews have become established as an alternative to traditional mail surveys for collecting epidemiological data in public health research. However, the use of telephone and mail surveys raises the question of to what extent the results of different data collection methods deviate from one another. We therefore set out to study possible differences in using telephone and mail survey methods to measure health-related quality of life and emotional and behavioural problems in children and adolescents. A total of 1700 German children aged 8-18 years and their parents were interviewed randomly either by telephone or by mail. Health-related Quality of Life (HRQoL) and mental health problems (MHP) were assessed using the KINDL-R Quality of Life instrument and the Strengths and Difficulties Questionnaire (SDQ) children's self-report and parent proxy report versions. Mean Differences ("d" effect size) and differences in Cronbach alpha were examined across modes of administration. Pearson correlation between children's and parents' scores was calculated within a multi-trait-multi-method (MTMM) analysis and compared across survey modes using Fisher-Z transformation. Telephone and mail survey methods resulted in similar completion rates and similar socio-demographic and socio-economic makeups of the samples. Telephone methods resulted in more positive self- and parent proxy reports of children's HRQoL (SMD survey self/proxy Total: 0.84/0.87). KINDL MTMM results were weaker for the phone surveys: mono-trait-multi-method mean r = 0.31 (mail: r = 0.45); multi-trait-mono-method mean (self/parents) r = 0.29/0.36 (mail: r = 0.34/0.40); multi-trait-multi-method mean r = 0.14 (mail: r = 0.21). Weaker MTMM results were also observed for the phone administered SDQ: mono-trait-multi-method mean r = 0.32 (mail: r = 0.40); multi-trait-mono-method mean (self/parents) r = 0.24/0.30 (mail: r = 0.20/0.32); multi-trait-multi-method mean r = 0.14 (mail = 0.14). The SDQ

  14. Efficient free energy calculations by combining two complementary tempering sampling methods.

    Science.gov (United States)

    Xie, Liangxu; Shen, Lin; Chen, Zhe-Ning; Yang, Mingjun

    2017-01-14

    Although energy barriers can be efficiently crossed in the reaction coordinate (RC) guided sampling, this type of method suffers from identification of the correct RCs or requirements of high dimensionality of the defined RCs for a given system. If only the approximate RCs with significant barriers are used in the simulations, hidden energy barriers with small to medium height would exist in other degrees of freedom (DOFs) relevant to the target process and consequently cause the problem of insufficient sampling. To address the sampling in this so-called hidden barrier situation, here we propose an effective approach to combine temperature accelerated molecular dynamics (TAMD), an efficient RC-guided sampling method, with the integrated tempering sampling (ITS), a generalized ensemble sampling method. In this combined ITS-TAMD method, the sampling along the major RCs with high energy barriers is guided by TAMD and the sampling of the rest of the DOFs with lower but not negligible barriers is enhanced by ITS. The performance of ITS-TAMD to three systems in the processes with hidden barriers has been examined. In comparison to the standalone TAMD or ITS approach, the present hybrid method shows three main improvements. (1) Sampling efficiency can be improved at least five times even if in the presence of hidden energy barriers. (2) The canonical distribution can be more accurately recovered, from which the thermodynamic properties along other collective variables can be computed correctly. (3) The robustness of the selection of major RCs suggests that the dimensionality of necessary RCs can be reduced. Our work shows more potential applications of the ITS-TAMD method as the efficient and powerful tool for the investigation of a broad range of interesting cases.

  15. SnagPRO: snag and tree sampling and analysis methods for wildlife

    Science.gov (United States)

    Lisa J. Bate; Michael J. Wisdom; Edward O. Garton; Shawn C. Clabough

    2008-01-01

    We describe sampling methods and provide software to accurately and efficiently estimate snag and tree densities at desired scales to meet a variety of research and management objectives. The methods optimize sampling effort by choosing a plot size appropriate for the specified forest conditions and sampling goals. Plot selection and data analyses are supported by...

  16. Soil separator and sampler and method of sampling

    Science.gov (United States)

    O'Brien, Barry H [Idaho Falls, ID; Ritter, Paul D [Idaho Falls, ID

    2010-02-16

    A soil sampler includes a fluidized bed for receiving a soil sample. The fluidized bed may be in communication with a vacuum for drawing air through the fluidized bed and suspending particulate matter of the soil sample in the air. In a method of sampling, the air may be drawn across a filter, separating the particulate matter. Optionally, a baffle or a cyclone may be included within the fluidized bed for disentrainment, or dedusting, so only the finest particulate matter, including asbestos, will be trapped on the filter. The filter may be removable, and may be tested to determine the content of asbestos and other hazardous particulate matter in the soil sample.

  17. Survey of post-Chernobyl contamination in Sumava region using various methods

    International Nuclear Information System (INIS)

    Drabova, D.; Filgas, R.; Malatova, I.; Cespirova, I.; Foltanova, S.; Hoeschl, V.; Roudny, R.; Jurza, P.; Pichl, R.

    1998-01-01

    A nation-wide survey of fallout and soil contamination was made immediately after the Chernobyl accident, on 16-18 June 1986. This, however, could not be done near the Bavarian and Austrian border with a special restricted-access regime. Measurements were completed there 10 years later. Cesium deposition was examined by the airborne scintillation and semiconductor spectrometric systems, complemented with ground in-situ spectrometry and measurement of soil samples at selected sites. The 137 Cs deposition in July 1996, as obtained by ENMOS airborne measurement, ground in-situ gamma spectrometry, and soil sampling lay within the ranges of 12-65, 15-63, and 7-81 kBq/m 2 , respectively. The cesium activity in the individual soil samples in each sampling point varied by more than one order of magnitude. (P.A.)

  18. Detecting spatial structures in throughfall data: The effect of extent, sample size, sampling design, and variogram estimation method

    Science.gov (United States)

    Voss, Sebastian; Zimmermann, Beate; Zimmermann, Alexander

    2016-09-01

    In the last decades, an increasing number of studies analyzed spatial patterns in throughfall by means of variograms. The estimation of the variogram from sample data requires an appropriate sampling scheme: most importantly, a large sample and a layout of sampling locations that often has to serve both variogram estimation and geostatistical prediction. While some recommendations on these aspects exist, they focus on Gaussian data and high ratios of the variogram range to the extent of the study area. However, many hydrological data, and throughfall data in particular, do not follow a Gaussian distribution. In this study, we examined the effect of extent, sample size, sampling design, and calculation method on variogram estimation of throughfall data. For our investigation, we first generated non-Gaussian random fields based on throughfall data with large outliers. Subsequently, we sampled the fields with three extents (plots with edge lengths of 25 m, 50 m, and 100 m), four common sampling designs (two grid-based layouts, transect and random sampling) and five sample sizes (50, 100, 150, 200, 400). We then estimated the variogram parameters by method-of-moments (non-robust and robust estimators) and residual maximum likelihood. Our key findings are threefold. First, the choice of the extent has a substantial influence on the estimation of the variogram. A comparatively small ratio of the extent to the correlation length is beneficial for variogram estimation. Second, a combination of a minimum sample size of 150, a design that ensures the sampling of small distances and variogram estimation by residual maximum likelihood offers a good compromise between accuracy and efficiency. Third, studies relying on method-of-moments based variogram estimation may have to employ at least 200 sampling points for reliable variogram estimates. These suggested sample sizes exceed the number recommended by studies dealing with Gaussian data by up to 100 %. Given that most previous

  19. Culture methods of allograft musculoskeletal tissue samples in Australian bacteriology laboratories.

    Science.gov (United States)

    Varettas, Kerry

    2013-12-01

    Samples of allograft musculoskeletal tissue are cultured by bacteriology laboratories to determine the presence of bacteria and fungi. In Australia, this testing is performed by 6 TGA-licensed clinical bacteriology laboratories with samples received from 10 tissue banks. Culture methods of swab and tissue samples employ a combination of solid agar and/or broth media to enhance micro-organism growth and maximise recovery. All six Australian laboratories receive Amies transport swabs and, except for one laboratory, a corresponding biopsy sample for testing. Three of the 6 laboratories culture at least one allograft sample directly onto solid agar. Only one laboratory did not use a broth culture for any sample received. An international literature review found that a similar combination of musculoskeletal tissue samples were cultured onto solid agar and/or broth media. Although variations of allograft musculoskeletal tissue samples, culture media and methods are used in Australian and international bacteriology laboratories, validation studies and method evaluations have challenged and supported their use in recovering fungi and aerobic and anaerobic bacteria.

  20. Comparison of self-administered survey questionnaire responses collected using mobile apps versus other methods.

    Science.gov (United States)

    Marcano Belisario, José S; Jamsek, Jan; Huckvale, Kit; O'Donoghue, John; Morrison, Cecily P; Car, Josip

    2015-07-27

    Self-administered survey questionnaires are an important data collection tool in clinical practice, public health research and epidemiology. They are ideal for achieving a wide geographic coverage of the target population, dealing with sensitive topics and are less resource-intensive than other data collection methods. These survey questionnaires can be delivered electronically, which can maximise the scalability and speed of data collection while reducing cost. In recent years, the use of apps running on consumer smart devices (i.e., smartphones and tablets) for this purpose has received considerable attention. However, variation in the mode of delivering a survey questionnaire could affect the quality of the responses collected. To assess the impact that smartphone and tablet apps as a delivery mode have on the quality of survey questionnaire responses compared to any other alternative delivery mode: paper, laptop computer, tablet computer (manufactured before 2007), short message service (SMS) and plastic objects. We searched MEDLINE, EMBASE, PsycINFO, IEEEXplore, Web of Science, CABI: CAB Abstracts, Current Contents Connect, ACM Digital, ERIC, Sociological Abstracts, Health Management Information Consortium, the Campbell Library and CENTRAL. We also searched registers of current and ongoing clinical trials such as ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform. We also searched the grey literature in OpenGrey, Mobile Active and ProQuest Dissertation & Theses. Lastly, we searched Google Scholar and the reference lists of included studies and relevant systematic reviews. We performed all searches up to 12 and 13 April 2015. We included parallel randomised controlled trials (RCTs), crossover trials and paired repeated measures studies that compared the electronic delivery of self-administered survey questionnaires via a smartphone or tablet app with any other delivery mode. We included data obtained from

  1. Detection of protozoa in water samples by formalin/ether concentration method.

    Science.gov (United States)

    Lora-Suarez, Fabiana; Rivera, Raul; Triviño-Valencia, Jessica; Gomez-Marin, Jorge E

    2016-09-01

    Methods to detect protozoa in water samples are expensive and laborious. We evaluated the formalin/ether concentration method to detect Giardia sp., Cryptosporidium sp. and Toxoplasma in water. In order to test the properties of the method, we spiked water samples with different amounts of each protozoa (0, 10 and 50 cysts or oocysts) in a volume of 10 L of water. Immunofluorescence assay was used for detection of Giardia and Cryptosporidium. Toxoplasma oocysts were identified by morphology. The mean percent of recovery in 10 repetitions of the entire method, in 10 samples spiked with ten parasites and read by three different observers, were for Cryptosporidium 71.3 ± 12, for Giardia 63 ± 10 and for Toxoplasma 91.6 ± 9 and the relative standard deviation of the method was of 17.5, 17.2 and 9.8, respectively. Intraobserver variation as measured by intraclass correlation coefficient, was fair for Toxoplasma, moderate for Cryptosporidium and almost perfect for Giardia. The method was then applied in 77 samples of raw and drinkable water in three different plant of water treatment. Cryptosporidium was found in 28 of 77 samples (36%) and Giardia in 31 of 77 samples (40%). Theses results identified significant differences in treatment process to reduce the presence of Giardia and Cryptosporidium. In conclusion, the formalin ether method to concentrate protozoa in water is a new alternative for low resources countries, where is urgently need to monitor and follow the presence of theses protozoa in drinkable water. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Sample representativeness verification of the FADN CZ farm business sample

    Directory of Open Access Journals (Sweden)

    Marie Prášilová

    2011-01-01

    Full Text Available Sample representativeness verification is one of the key stages of statistical work. After having joined the European Union the Czech Republic joined also the Farm Accountancy Data Network system of the Union. This is a sample of bodies and companies doing business in agriculture. Detailed production and economic data on the results of farming business are collected from that sample annually and results for the entire population of the country´s farms are then estimated and assessed. It is important hence, that the sample be representative. Representativeness is to be assessed as to the number of farms included in the survey and also as to the degree of accordance of the measures and indices as related to the population. The paper deals with the special statistical techniques and methods of the FADN CZ sample representativeness verification including the necessary sample size statement procedure. The Czech farm population data have been obtained from the Czech Statistical Office data bank.

  3. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Matthias, E-mail: matthias.schindler@physik.uni-erlangen.de; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-15

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO{sub 2} and reduced to graphite to determine {sup 14}C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  4. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    Science.gov (United States)

    Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-01

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  5. Assessment of reagent effectiveness and preservation methods for equine faecal samples

    Directory of Open Access Journals (Sweden)

    Eva Vavrouchova

    2015-03-01

    Full Text Available The aim of our study was to identify the most suitable flotation solution and effective preservation method for the examination of equine faeces samples using the FLOTAC technique. Samples from naturally infected horses were transported to the laboratory andanalysed accordingly. The sample from each horse was homogenized and divided into four parts: one was frozen, another two were preserved in different reagents such as sodium acetate-acetic-acid–formalin (SAF or 5% formalin.The last part was examined as a fresh sample in three different flotation solutions (Sheather´s solution, sodium chloride and sodium nitrate solution, all with a specific gravity 1.200. The preserved samples were examined in the period from 14 to21days after collection. According to our results, the sucrose solution was the most suitable flotation solution for fresh samples (small strongyle egg per gram was 706 compared to 360 in sodium chlorid and 507 in sodium nitrate and the sodium nitrate solution was the most efficient for the preserved samples (egg per gram was 382 compared to 295 in salt solution and 305 in sucrose solution. Freezing appears to be the most effective method of sample preservation, resulting in minimal damage to fragile strongyle eggs and therefore it is the most simple and effective preservation method for the examination of large numbers of faecal samples without the necessity of examining them all within 48 hours of collection. Deep freezing as a preservation method for equine faeces samples has not, according to our knowledge, been yet published.

  6. Marine mammal surveys in Dutch waters in 2013

    NARCIS (Netherlands)

    Geelhoed, S.C.V.; Scheidat, M.; Bemmelen, van R.S.A.

    2014-01-01

    In March/April 2013 aerial surveys to estimate the abundance of Harbour porpoises Phocoena phocoena on the Dutch Continental Shelf were conducted. These surveys were conducted along predetermined track lines using distance sampling methods in four areas: A “Dogger Bank”, B “Offshore”, C “Frisian

  7. Probability Sampling - A Guideline for Quantitative Health Care ...

    African Journals Online (AJOL)

    A more direct definition is the method used for selecting a given ... description of the chosen population, the sampling procedure giving ... target population, precision, and stratification. The ... survey estimates, it is recommended that researchers first analyze a .... The optimum sample size has a relation to the type of planned ...

  8. A comparison of survey methods for documenting presence of Myotis leibii (Eastern Small-Footed Bats) at roosting areas in Western Virginia

    Science.gov (United States)

    Huth, John K.; Silvis, Alexander; Moosman, Paul R.; Ford, W. Mark; Sweeten, Sara E.

    2015-01-01

    Many aspects of foraging and roosting habitat of Myotis leibii (Eastern Small-Footed Bat), an emergent rock roosting-obligate, are poorly described. Previous comparisons of effectiveness of acoustic sampling and mist-net captures have not included Eastern Small-Footed Bat. Habitat requirements of this species differ from congeners in the region, and it is unclear whether survey protocols developed for other species are applicable. Using data from three overlapping studies at two sampling sites in western Virginia’s central Appalachian Mountains, detection probabilities were examined for three survey methods (acoustic surveys with automated identification of calls, visual searches of rock crevices, and mist-netting) for use in the development of “best practices” for future surveys and monitoring. Observer effects were investigated using an expanded version of visual search data. Results suggested that acoustic surveys with automated call identification are not effective for documenting presence of Eastern Small-Footed Bats on talus slopes (basal detection rate of 0%) even when the species is known to be present. The broadband, high frequency echolocation calls emitted by Eastern Small-Footed Bat may be prone to attenuation by virtue of their high frequencies, and these factors, along with signal reflection, lower echolocation rates or possible misidentification to other bat species over talus slopes may all have contributed to poor acoustic survey success. Visual searches and mist-netting of emergent rock had basal detection probabilities of 91% and 75%, respectively. Success of visual searches varied among observers, but detection probability improved with practice. Additionally, visual searches were considerably more economical than mist-netting.

  9. Extending the alias Monte Carlo sampling method to general distributions

    International Nuclear Information System (INIS)

    Edwards, A.L.; Rathkopf, J.A.; Smidt, R.K.

    1991-01-01

    The alias method is a Monte Carlo sampling technique that offers significant advantages over more traditional methods. It equals the accuracy of table lookup and the speed of equal probable bins. The original formulation of this method sampled from discrete distributions and was easily extended to histogram distributions. We have extended the method further to applications more germane to Monte Carlo particle transport codes: continuous distributions. This paper presents the alias method as originally derived and our extensions to simple continuous distributions represented by piecewise linear functions. We also present a method to interpolate accurately between distributions tabulated at points other than the point of interest. We present timing studies that demonstrate the method's increased efficiency over table lookup and show further speedup achieved through vectorization. 6 refs., 12 figs., 2 tabs

  10. A Survey of Methods for Gas-Lift Optimization

    Directory of Open Access Journals (Sweden)

    Kashif Rashid

    2012-01-01

    Full Text Available This paper presents a survey of methods and techniques developed for the solution of the continuous gas-lift optimization problem over the last two decades. These range from isolated single-well analysis all the way to real-time multivariate optimization schemes encompassing all wells in a field. While some methods are clearly limited due to their neglect of treating the effects of inter-dependent wells with common flow lines, other methods are limited due to the efficacy and quality of the solution obtained when dealing with large-scale networks comprising hundreds of difficult to produce wells. The aim of this paper is to provide an insight into the approaches developed and to highlight the challenges that remain.

  11. Research and application of sampling and analysis method of sodium aerosol

    International Nuclear Information System (INIS)

    Yu Xiaochen; Guo Qingzhou; Wen Ximeng

    1998-01-01

    Method of sampling-analysis for sodium aerosol is researched. The vacuum sampling technology is used in the sampling process, and the analysis method adopted is volumetric analysis and atomic absorption. When the absolute content of sodium is in the rang of 0.1 mg to 1.0 mg, the deviation of results between volumetric analysis and atomic absorption is less than 2%. The method has been applied in a sodium aerosol removal device successfully. The analysis range, accuracy and precision can meet the requirements for researching sodium aerosol

  12. A novel method for fission product noble gas sampling

    International Nuclear Information System (INIS)

    Jain, S.K.; Prakash, Vivek; Singh, G.K.; Vinay, Kr.; Awsthi, A.; Bihari, K.; Joyson, R.; Manu, K.; Gupta, Ashok

    2008-01-01

    Noble gases occur to some extent in the Earth's atmosphere, but the concentrations of all but argon are exceedingly low. Argon is plentiful, constituting almost 1 % of the air. Fission Product Noble Gases (FPNG) are produced by nuclear fission and large parts of FPNG is produced in Nuclear reactions. FPNG are b-j emitters and contributing significantly in public dose. During normal operation of reactor release of FPNG is negligible but its release increases in case of fuel failure. Xenon, a member of FPNG family helps in identification of fuel failure and its extent in PHWRs. Due to above reasons it becomes necessary to assess the FPNG release during operation of NPPs. Presently used methodology of assessment of FPNG, at almost all power stations is Computer based gamma ray spectrometry. This provides fission product Noble gases nuclide identification through peak search of spectra. The air sample for the same is collected by grab sampling method, which has inherent disadvantages. An alternate method was developed at Rajasthan Atomic Power Station (RAPS) - 3 and 4 for assessment of FPNG, which uses adsorption phenomena for collection of air samples. This report presents details of sampling method for FPNG and noble gases in different systems of Nuclear Power Plant. (author)

  13. Characteristics and correlation of various radiation measuring methods in spatial radiation measurement

    International Nuclear Information System (INIS)

    Yoneda, Kazuhiro; Tonouchi, Shigemasa

    1992-01-01

    When the survey of the state of natural radiation distribution was carried out, for the purpose of examining the useful measuring method, the comparison of the γ-ray dose rate calculated from survey meter method, in-situ measuring method and the measuring method by sampling soil was carried out. Between the in-situ measuring method and the survey meter method, the correlation Y=0.986X+5.73, r=0.903, n=18, P<0.01 was obtained, and the high correlation having the inclination of nearly 1 was shown. Between the survey meter method and the measuring method by sampling soil, the correlation Y=1.297X-10.30, r=0.966, n=20 P<0.01 was obtained, and the high correlation was shown, but as for the dose rate contribution, the disparities of 36% in U series, 6% in Th series and 20% in K-40 were observed. For the survey of the state of natural radiation distribution, the method of using in combination the survey meter method and the in-situ measuring method or the measuring method by sampling soil is suitable. (author)

  14. The Sloan Digital Sky Survey Quasar Lens Search. IV. Statistical Lens Sample from the Fifth Data Release

    Energy Technology Data Exchange (ETDEWEB)

    Inada, Naohisa; /Wako, RIKEN /Tokyo U., ICEPP; Oguri, Masamune; /Natl. Astron. Observ. of Japan /Stanford U., Phys. Dept.; Shin, Min-Su; /Michigan U. /Princeton U. Observ.; Kayo, Issha; /Tokyo U., ICRR; Strauss, Michael A.; /Princeton U. Observ.; Hennawi, Joseph F.; /UC, Berkeley /Heidelberg, Max Planck Inst. Astron.; Morokuma, Tomoki; /Natl. Astron. Observ. of Japan; Becker, Robert H.; /LLNL, Livermore /UC, Davis; White, Richard L.; /Baltimore, Space Telescope Sci.; Kochanek, Christopher S.; /Ohio State U.; Gregg, Michael D.; /LLNL, Livermore /UC, Davis /Exeter U.

    2010-05-01

    We present the second report of our systematic search for strongly lensed quasars from the data of the Sloan Digital Sky Survey (SDSS). From extensive follow-up observations of 136 candidate objects, we find 36 lenses in the full sample of 77,429 spectroscopically confirmed quasars in the SDSS Data Release 5. We then define a complete sample of 19 lenses, including 11 from our previous search in the SDSS Data Release 3, from the sample of 36,287 quasars with i < 19.1 in the redshift range 0.6 < z < 2.2, where we require the lenses to have image separations of 1 < {theta} < 20 and i-band magnitude differences between the two images smaller than 1.25 mag. Among the 19 lensed quasars, 3 have quadruple-image configurations, while the remaining 16 show double images. This lens sample constrains the cosmological constant to be {Omega}{sub {Lambda}} = 0.84{sub -0.08}{sup +0.06}(stat.){sub -0.07}{sup + 0.09}(syst.) assuming a flat universe, which is in good agreement with other cosmological observations. We also report the discoveries of 7 binary quasars with separations ranging from 1.1 to 16.6, which are identified in the course of our lens survey. This study concludes the construction of our statistical lens sample in the full SDSS-I data set.

  15. THE FMOS-COSMOS SURVEY OF STAR-FORMING GALAXIES AT z ∼ 1.6. III. SURVEY DESIGN, PERFORMANCE, AND SAMPLE CHARACTERISTICS

    Energy Technology Data Exchange (ETDEWEB)

    Silverman, J. D.; Sugiyama, N. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, 277-8583 (Japan); Kashino, D. [Division of Particle and Astrophysical Science, Graduate School of Science, Nagoya University, Nagoya, 464-8602 (Japan); Sanders, D.; Zahid, J.; Kewley, L. J.; Chu, J.; Hasinger, G. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI, 96822 (United States); Kartaltepe, J. S. [National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ, 85719 (United States); Arimoto, N. [Subaru Telescope, 650 North A’ohoku Place, Hilo, Hawaii, 96720 (United States); Renzini, A. [Instituto Nazionale de Astrofisica, Osservatorio Astronomico di Padova, vicolo dell’Osservatorio 5, I-35122, Padova, Italy, EU (Italy); Rodighiero, G.; Baronchelli, I. [Dipartimento di Fisica e Astronomia, Universita di Padova, vicolo Osservatorio, 3, I-35122, Padova (Italy); Daddi, E.; Juneau, S. [Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, Irfu/Service d’Astrophysique, CEA Saclay (France); Nagao, T. [Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-cho, Matsuyama 790-8577 (Japan); Lilly, S. J.; Carollo, C. M. [Institute of Astronomy, ETH Zürich, CH-8093, Zürich (Switzerland); Capak, P. [Spitzer Science Center, California Institute of Technology, Pasadena, CA 91125 (United States); Ilbert, O., E-mail: john.silverman@ipmu.jp [Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388, Marseille (France); and others

    2015-09-15

    We present a spectroscopic survey of galaxies in the COSMOS field using the Fiber Multi-object Spectrograph (FMOS), a near-infrared instrument on the Subaru Telescope. Our survey is specifically designed to detect the Hα emission line that falls within the H-band (1.6–1.8 μm) spectroscopic window from star-forming galaxies with 1.4 < z < 1.7 and M{sub stellar} ≳ 10{sup 10} M{sub ⊙}. With the high multiplex capability of FMOS, it is now feasible to construct samples of over 1000 galaxies having spectroscopic redshifts at epochs that were previously challenging. The high-resolution mode (R ∼ 2600) effectively separates Hα and [N ii]λ6585, thus enabling studies of the gas-phase metallicity and photoionization state of the interstellar medium. The primary aim of our program is to establish how star formation depends on stellar mass and environment, both recognized as drivers of galaxy evolution at lower redshifts. In addition to the main galaxy sample, our target selection places priority on those detected in the far-infrared by Herschel/PACS to assess the level of obscured star formation and investigate, in detail, outliers from the star formation rate (SFR)—stellar mass relation. Galaxies with Hα detections are followed up with FMOS observations at shorter wavelengths using the J-long (1.11–1.35 μm) grating to detect Hβ and [O iii]λ5008 which provides an assessment of the extinction required to measure SFRs not hampered by dust, and an indication of embedded active galactic nuclei. With 460 redshifts measured from 1153 spectra, we assess the performance of the instrument with respect to achieving our goals, discuss inherent biases in the sample, and detail the emission-line properties. Our higher-level data products, including catalogs and spectra, are available to the community.

  16. Manual for the Portable Handheld Neutron Counter (PHNC) for Neutron Survey and the Measurement of Plutonium Samples

    International Nuclear Information System (INIS)

    Menlove, H.O.

    2005-01-01

    We have designed a portable neutron detector for passive neutron scanning measurement and coincidence counting of bulk samples of plutonium. The counter will be used for neutron survey applications as well as the measurement of plutonium samples for portable applications. The detector uses advanced design 3 He tubes to increase the efficiency and battery operated shift register electronics. This report describes the hardware, performance, and calibration for the system

  17. An automated radiological survey method for performing site remediation and decommissioning

    International Nuclear Information System (INIS)

    Handy, R.G.; Bolch, W.E.; Harder, G.F.; Tolaymat, T.M.

    1994-01-01

    A portable, computer-based method of performing environmental monitoring and assessment for site remediation and decommissioning has been developed. The integrated system has been developed to provide for survey time reductions and real-time data analysis. The technique utilizes a notebook 486 computer with the necessary hardware and software components that makes it possible to be used in an almost unlimited number of environmental monitoring and assessment scenarios. The results from a pilot, open-quotes hide-and-seekclose quotes gamma survey and an actual alpha decontamination survey were elucidated. It was found that a open-quotes hide-and-seekclose quotes survey could come up with timely and accurate conclusions about the position of the source. The use of the automated system in a Th-232 alpha survey resulted in a reduction in the standard time necessary to do a radiological survey. In addition, the ability to analyze the data on-site allowed for identification and location of areas which needed further decontamination. Finally, a discussion on possible future improvements and field conclusions was made

  18. Realisation Ratios in the Capital Expenditure Survey

    OpenAIRE

    Leon Berkelmans; Gareth Spence

    2013-01-01

    The Australian Bureau of Statistics capital expenditure survey is one of the inputs into the Reserve Bank’s forecasts for private business investment. This article considers several methods for interpreting the expectations data from this survey and evaluates these methods using out-of-sample forecasts. Forecasts based on long-run average realisation ratios are found to be the most accurate of the options considered, although the use of these forecasts for predicting investment in the nationa...

  19. Effects of phone versus mail survey methods on the measurement of health-related quality of life and emotional and behavioural problems in adolescents

    Directory of Open Access Journals (Sweden)

    Ravens-Sieberer Ulrike

    2009-12-01

    Full Text Available Abstract Background Telephone interviews have become established as an alternative to traditional mail surveys for collecting epidemiological data in public health research. However, the use of telephone and mail surveys raises the question of to what extent the results of different data collection methods deviate from one another. We therefore set out to study possible differences in using telephone and mail survey methods to measure health-related quality of life and emotional and behavioural problems in children and adolescents. Methods A total of 1700 German children aged 8-18 years and their parents were interviewed randomly either by telephone or by mail. Health-related Quality of Life (HRQoL and mental health problems (MHP were assessed using the KINDL-R Quality of Life instrument and the Strengths and Difficulties Questionnaire (SDQ children's self-report and parent proxy report versions. Mean Differences ("d" effect size and differences in Cronbach alpha were examined across modes of administration. Pearson correlation between children's and parents' scores was calculated within a multi-trait-multi-method (MTMM analysis and compared across survey modes using Fisher-Z transformation. Results Telephone and mail survey methods resulted in similar completion rates and similar socio-demographic and socio-economic makeups of the samples. Telephone methods resulted in more positive self- and parent proxy reports of children's HRQoL (SMD ≤ 0.27 and MHP (SMD ≤ 0.32 on many scales. For the phone administered KINDL, lower Cronbach alpha values (self/proxy Total: 0.79/0.84 were observed (mail survey self/proxy Total: 0.84/0.87. KINDL MTMM results were weaker for the phone surveys: mono-trait-multi-method mean r = 0.31 (mail: r = 0.45; multi-trait-mono-method mean (self/parents r = 0.29/0.36 (mail: r = 0.34/0.40; multi-trait-multi-method mean r = 0.14 (mail: r = 0.21. Weaker MTMM results were also observed for the phone administered SDQ: mono-trait-multi-method

  20. Transformation-cost time-series method for analyzing irregularly sampled data.

    Science.gov (United States)

    Ozken, Ibrahim; Eroglu, Deniz; Stemler, Thomas; Marwan, Norbert; Bagci, G Baris; Kurths, Jürgen

    2015-06-01

    Irregular sampling of data sets is one of the challenges often encountered in time-series analysis, since traditional methods cannot be applied and the frequently used interpolation approach can corrupt the data and bias the subsequence analysis. Here we present the TrAnsformation-Cost Time-Series (TACTS) method, which allows us to analyze irregularly sampled data sets without degenerating the quality of the data set. Instead of using interpolation we consider time-series segments and determine how close they are to each other by determining the cost needed to transform one segment into the following one. Using a limited set of operations-with associated costs-to transform the time series segments, we determine a new time series, that is our transformation-cost time series. This cost time series is regularly sampled and can be analyzed using standard methods. While our main interest is the analysis of paleoclimate data, we develop our method using numerical examples like the logistic map and the Rössler oscillator. The numerical data allows us to test the stability of our method against noise and for different irregular samplings. In addition we provide guidance on how to choose the associated costs based on the time series at hand. The usefulness of the TACTS method is demonstrated using speleothem data from the Secret Cave in Borneo that is a good proxy for paleoclimatic variability in the monsoon activity around the maritime continent.

  1. Transformation-cost time-series method for analyzing irregularly sampled data

    Science.gov (United States)

    Ozken, Ibrahim; Eroglu, Deniz; Stemler, Thomas; Marwan, Norbert; Bagci, G. Baris; Kurths, Jürgen

    2015-06-01

    Irregular sampling of data sets is one of the challenges often encountered in time-series analysis, since traditional methods cannot be applied and the frequently used interpolation approach can corrupt the data and bias the subsequence analysis. Here we present the TrAnsformation-Cost Time-Series (TACTS) method, which allows us to analyze irregularly sampled data sets without degenerating the quality of the data set. Instead of using interpolation we consider time-series segments and determine how close they are to each other by determining the cost needed to transform one segment into the following one. Using a limited set of operations—with associated costs—to transform the time series segments, we determine a new time series, that is our transformation-cost time series. This cost time series is regularly sampled and can be analyzed using standard methods. While our main interest is the analysis of paleoclimate data, we develop our method using numerical examples like the logistic map and the Rössler oscillator. The numerical data allows us to test the stability of our method against noise and for different irregular samplings. In addition we provide guidance on how to choose the associated costs based on the time series at hand. The usefulness of the TACTS method is demonstrated using speleothem data from the Secret Cave in Borneo that is a good proxy for paleoclimatic variability in the monsoon activity around the maritime continent.

  2. Survey of methods used to determine if a patient has a deep vein thrombosis: An exploratory research report.

    Science.gov (United States)

    Heick, John D; Farris, James W

    2017-09-01

    The use of evidence-based practice (EBP) is encouraged in the physical therapy profession, but integrating evidence into practice can be difficult for clinicians because of lack of time and other constraints. To survey physical therapy clinical instructors and determine the methods they use for screening for deep vein thrombosis (DVT), a type of venous thromboembolism (VTE) in the lower extremities. Exploratory survey. Twelve survey questions written specifically for this study were sent to a convenience sample of clinical instructors associated with seven universities across 43 states. Eight hundred fifty clinical instructors (22.4% response rate) completed the survey. Of those who responded, 80.5% were taught to use Homans sign to screen for a possible DVT in their entry-level education and 67.9% continued to use Homans sign in clinical practice. Regardless of post-graduate education, respondents were more likely to choose Homans sign than a clinical decision rule (CDR) to screen for a suspected DVT. Additionally, nearly two-thirds of respondents failed to correctly identify one or more of the major risk factors for developing a DVT/VTE. The response rate was 22.4% and therefore may not fully represent the population of physical therapy clinical instructors in the United States. Results from this exploratory survey indicated that approximately two-thirds of physical therapy clinical instructors used outdated DVT/VTE screening methods that they were taught in their entry-level education and nearly two-thirds did not identify the major risk factors associated with DVT/VTE. These results suggest that change is necessary in physical therapy education, clinical practice, and continuing professional development to ensure a more evidenced-based identification of DVT and VTE.

  3. Different methods for volatile sampling in mammals.

    Directory of Open Access Journals (Sweden)

    Marlen Kücklich

    Full Text Available Previous studies showed that olfactory cues are important for mammalian communication. However, many specific compounds that convey information between conspecifics are still unknown. To understand mechanisms and functions of olfactory cues, olfactory signals such as volatile compounds emitted from individuals need to be assessed. Sampling of animals with and without scent glands was typically conducted using cotton swabs rubbed over the skin or fur and analysed by gas chromatography-mass spectrometry (GC-MS. However, this method has various drawbacks, including a high level of contaminations. Thus, we adapted two methods of volatile sampling from other research fields and compared them to sampling with cotton swabs. To do so we assessed the body odor of common marmosets (Callithrix jacchus using cotton swabs, thermal desorption (TD tubes and, alternatively, a mobile GC-MS device containing a thermal desorption trap. Overall, TD tubes comprised most compounds (N = 113, with half of those compounds being volatile (N = 52. The mobile GC-MS captured the fewest compounds (N = 35, of which all were volatile. Cotton swabs contained an intermediate number of compounds (N = 55, but very few volatiles (N = 10. Almost all compounds found with the mobile GC-MS were also captured with TD tubes (94%. Hence, we recommend TD tubes for state of the art sampling of body odor of mammals or other vertebrates, particularly for field studies, as they can be easily transported, stored and analysed with high performance instruments in the lab. Nevertheless, cotton swabs capture compounds which still may contribute to the body odor, e.g. after bacterial fermentation, while profiles from mobile GC-MS include only the most abundant volatiles of the body odor.

  4. A practical tissue sampling method using ordinary paper for molecular detection of infectious bursal disease virus RNA by RT-PCR.

    Science.gov (United States)

    Maw, Min Thein; Yamaguchi, Tsuyoshi; Kasanga, Christopher J; Terasaki, Kaori; Fukushi, Hideto

    2006-12-01

    A practical sampling method for bursal tissue using ordinary paper for molecular diagnosis of infectious bursal disease (IBD) was established. IBD virus-infected bursa was directly smeared on chromatography paper, filter paper, or stationery copy paper and was then fixed with absolute ethanol, Tris-HCl-saturated phenol, or phenol:chloroform:isoamyl alcohol (25:24:1). Flinders Technology Associates (FTA) card, which is designed for the collection of biological samples for molecular detection, was also used. After storage at 37 C for up to 30 days, total RNA directly extracted from the tissue fixed on the papers and FTA card were subjected to reverse transcriptase-polymerase chain reaction (RT-PCR) for detection of IBD virus (IBDV) RNA. In addition, the ability of each chemical used in the fixation and the FTA card to inactivate IBDV was evaluated. Regardless of the paper quality, storage period, and fixation method, IBDV RNA was consistently detected in all of the samples. IBDV in the bursal tissue was inactivated with phenol but not with ethanol or the unknown chemicals in FTA card. These results show that ordinary papers sustain the viral RNA, as does FTA card, but phenol fixation is superior to FTA card in inactivating IBDV. The new sampling method using ordinary paper with phenol fixation is safe, inexpensive, simple, and easy, and is thus suitable for conducting a global survey of IBD even where laboratory resources are limited. This practical method should contribute to the control of IBD worldwide.

  5. An open-population hierarchical distance sampling model

    Science.gov (United States)

    Sollmann, Rachel; Beth Gardner,; Richard B Chandler,; Royle, J. Andrew; T Scott Sillett,

    2015-01-01

    Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for direct estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for island scrub-jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying number of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

  6. An open-population hierarchical distance sampling model.

    Science.gov (United States)

    Sollmann, Rahel; Gardner, Beth; Chandler, Richard B; Royle, J Andrew; Sillett, T Scott

    2015-02-01

    Modeling population dynamics while accounting for imperfect detection is essential to monitoring programs. Distance sampling allows estimating population size while accounting for imperfect detection, but existing methods do not allow for estimation of demographic parameters. We develop a model that uses temporal correlation in abundance arising from underlying population dynamics to estimate demographic parameters from repeated distance sampling surveys. Using a simulation study motivated by designing a monitoring program for Island Scrub-Jays (Aphelocoma insularis), we investigated the power of this model to detect population trends. We generated temporally autocorrelated abundance and distance sampling data over six surveys, using population rates of change of 0.95 and 0.90. We fit the data generating Markovian model and a mis-specified model with a log-linear time effect on abundance, and derived post hoc trend estimates from a model estimating abundance for each survey separately. We performed these analyses for varying numbers of survey points. Power to detect population changes was consistently greater under the Markov model than under the alternatives, particularly for reduced numbers of survey points. The model can readily be extended to more complex demographic processes than considered in our simulations. This novel framework can be widely adopted for wildlife population monitoring.

  7. Musculoskeletal impairment survey in Rwanda: Design of survey tool, survey methodology, and results of the pilot study (a cross sectional survey

    Directory of Open Access Journals (Sweden)

    Simms Victoria

    2007-03-01

    Full Text Available Abstract Background Musculoskeletal impairment (MSI is an important cause of morbidity and mortality worldwide, especially in developing countries. Prevalence studies for MSI in the developing world have used varying methodologies and are seldom directly comparable. This study aimed to develop a new tool to screen for and diagnose MSI and to pilot test the methodology for a national survey in Rwanda. Methods A 7 question screening tool to identify cases of MSI was developed through literature review and discussions with healthcare professionals. To validate the tool, trained rehabilitation technicians screened 93 previously identified gold standard 'cases' and 86 'non cases'. Sensitivity, specificity and positive predictive value were calculated. A standardised examination protocol was developed to determine the aetiology and diagnosis of MSI for those who fail the screening test. For the national survey in Rwanda, multistage cluster random sampling, with probability proportional to size procedures will be used for selection of a cross-sectional, nationally representative sample of the population. Households to be surveyed will be chosen through compact segment sampling and all individuals within chosen households will be screened. A pilot survey of 680 individuals was conducted using the protocol. Results: The screening tool demonstrated 99% sensitivity and 97% specificity for MSI, and a positive predictive value of 98%. During the pilot study 468 out of 680 eligible subjects (69% were screened. 45 diagnoses were identified in 38 persons who were cases of MSI. The subjects were grouped into categories based on diagnostic subgroups of congenital (1, traumatic (17, infective (2 neurological (6 and other acquired(19. They were also separated into mild (42.1%, moderate (42.1% and severe (15.8% cases, using an operational definition derived from the World Health Organisation's International Classification of Functioning, Disability and Health

  8. Research on 3-D terrain correction methods of airborne gamma-ray spectrometry survey

    International Nuclear Information System (INIS)

    Liu Yanyang; Liu Qingcheng; Zhang Zhiyong

    2008-01-01

    The general method of height correction is not effectual in complex terrain during the process of explaining airborne gamma-ray spectrometry data, and the 2-D terrain correction method researched in recent years is just available for correction of section measured. A new method of 3-D sector terrain correction is studied. The ground radiator is divided into many small sector radiators by the method, then the irradiation rate is calculated in certain survey distance, and the total value of all small radiate sources is regarded as the irradiation rate of the ground radiator at certain point of aero- survey, and the correction coefficients of every point are calculated which then applied to correct to airborne gamma-ray spectrometry data. The method can achieve the forward calculation, inversion calculation and terrain correction for airborne gamma-ray spectrometry survey in complex topography by dividing the ground radiator into many small sectors. Other factors are considered such as the un- saturated degree of measure scope, uneven-radiator content on ground, and so on. The results of for- ward model and an example analysis show that the 3-D terrain correction method is proper and effectual. (authors)

  9. Non-uniform sampling and wide range angular spectrum method

    International Nuclear Information System (INIS)

    Kim, Yong-Hae; Byun, Chun-Won; Oh, Himchan; Lee, JaeWon; Pi, Jae-Eun; Heon Kim, Gi; Lee, Myung-Lae; Ryu, Hojun; Chu, Hye-Yong; Hwang, Chi-Sun

    2014-01-01

    A novel method is proposed for simulating free space field propagation from a source plane to a destination plane that is applicable for both small and large propagation distances. The angular spectrum method (ASM) was widely used for simulating near field propagation, but it caused a numerical error when the propagation distance was large because of aliasing due to under sampling. Band limited ASM satisfied the Nyquist condition on sampling by limiting a bandwidth of a propagation field to avoid an aliasing error so that it could extend the applicable propagation distance of the ASM. However, the band limited ASM also made an error due to the decrease of an effective sampling number in a Fourier space when the propagation distance was large. In the proposed wide range ASM, we use a non-uniform sampling in a Fourier space to keep a constant effective sampling number even though the propagation distance is large. As a result, the wide range ASM can produce simulation results with high accuracy for both far and near field propagation. For non-paraxial wave propagation, we applied the wide range ASM to a shifted destination plane as well. (paper)

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

    CERN Document Server

    Liang, Faming; Carrol, Raymond J

    2010-01-01

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

  11. Comparison of Survey Data Collection Methods

    Directory of Open Access Journals (Sweden)

    VIDAL DÍAZ DE RADA

    2017-01-01

    Full Text Available This paper presents the results of a mixed-mode survey of the general population using a combination of postal, telephone, and Internet survey protocols. Potential respondents were invited to participate by ordinary mail and were allowed to choose their preferred response mode. The paper focuses on response quality (taking non-responses into consideration, fieldwork time and data collection cost. The results reveal that the Internet survey produces the lowest rate of non-responses and requires significantly less fieldwork time, although it is slightly more costly than the postal survey. However, when differences in cost structure are taken into account, we find that the same number of completed questionnaires could have been obtained through the Internet alone at a cost that is 18.2% lower than the mixed-mode survey.

  12. [A respondent-driven sampling survey on HIV and risk factors among men who have sex with men in Chongqing].

    Science.gov (United States)

    Ouyang, Lin; Feng, Lian-gui; Ding, Xian-bin; Zhao, Jin-kou; Xu, Jing; Han, Mei; Zhou, Chao

    2009-10-01

    To examine HIV prevalence and related risk factors among men who have sex with men (MSM) in Chongqing, and to explore the feasibility of using respondent-driven sampling (RDS) in the survey. Based on results from formative research, a RDS survey was designed and conducted to collect demographic, behavioral and serologic data. RDSAT was used to calculate point estimation and confidence intervals. SPSS was used for bi-variate analysis using RDSAT exported weighed data. NETDRAW was used to draw network diagram. Among 617 subjects recruited, the adjusted HIV and syphilis prevalence rates were 16.8% and 10.9%, respectively. 73.0% of the subjects were 20 to 29 years old and 72.9% were officially registered residents of Chongqing. 83.4% were single, with the proportion of students the highest, accounting for 24.6%. During the last six months, 83.4% of them reported ever having anal sex, and 54.0% reported having unprotected anal sex. This survey confirmed that Chongqing had a higher reported HIV prevalence among MSM than from other Chinese cities. Comprehensive intervention services were required to address this alarmingly high prevalence, with focus on intervention through internet and those having syphilis infection. RDS seemed one of the effective ways of recruiting hidden MSM populations in Chongqing which had a large population of active MSM who did not frequently visit MSM venues as compared with snowball method.

  13. Pseudo-populations a basic concept in statistical surveys

    CERN Document Server

    Quatember, Andreas

    2015-01-01

    This book emphasizes that artificial or pseudo-populations play an important role in statistical surveys from finite universes in two manners: firstly, the concept of pseudo-populations may substantially improve users’ understanding of various aspects in the sampling theory and survey methodology; an example of this scenario is the Horvitz-Thompson estimator. Secondly, statistical procedures exist in which pseudo-populations actually have to be generated. An example of such a scenario can be found in simulation studies in the field of survey sampling, where close-to-reality pseudo-populations are generated from known sample and population data to form the basis for the simulation process. The chapters focus on estimation methods, sampling techniques, nonresponse, questioning designs and statistical disclosure control.This book is a valuable reference in understanding the importance of the pseudo-population concept and applying it in teaching and research.

  14. GPR survey, as one of the best geophysical methods for social and industrial needs

    Science.gov (United States)

    Chernov, Anatolii

    2016-04-01

    This paper is about ways and methods of applying non-invasive geophysical method - Ground penetrating radar (GPR) survey in different spheres of science, industry, social life and culture. Author would like to show that geological methods could be widely used for solving great variety of industrial, human safety and other problems. In that article, we take GPR survey as an example of such useful geophysical methods. It is a fact that investigation of near surface underground medium is important process, which influence on development of different spheres of science and social life: investigation of near surface geology (layering, spreading of rock types, identification of voids, etc.), hydrogeology (depth to water horizons, their thickness), preparation step for construction of roads and buildings (civil geology, engineering geology), investigation of cultural heritage (burial places, building remains,...), ecological investigations (land slides, variation in underground water level, etc.), glaciology. These tasks can be solved by geological methods, but as usual, geophysical survey takes a lot of time and energy (especially electric current and resistivity methods, seismic survey). Author claims that GPR survey can be performed faster than other geophysical surveys and results of GPR survey are informative enough to make proper conclusions. Some problems even cannot be solved without GPR. For example, identification of burial place (one of author's research objects): results of magnetic and electric resistivity tomography survey do not contain enough information to identify burial place, but according to anomalies on GPR survey radarograms, presence of burial place can be proven. Identification of voids and non-magnetic objects also hardly can be done by another non-invasive geophysics surveys and GPR is applicable for that purpose. GPR can be applied for monitoring of dangerous processes in geological medium under roads, buildings, parks and other places of human

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

    Science.gov (United States)

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

    2014-01-01

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

  16. The effect of mode and context on survey results: Analysis of data from the Health Survey for England 2006 and the Boost Survey for London

    Directory of Open Access Journals (Sweden)

    Roth Marilyn A

    2010-09-01

    Full Text Available Abstract Background Health-related data at local level could be provided by supplementing national health surveys with local boosts. Self-completion surveys are less costly than interviews, enabling larger samples to be achieved for a given cost. However, even when the same questions are asked with the same wording, responses to survey questions may vary by mode of data collection. These measurement differences need to be investigated further. Methods The Health Survey for England in London ('Core' and a London Boost survey ('Boost' used identical sampling strategies but different modes of data collection. Some data were collected by face-to-face interview in the Core and by self-completion in the Boost; other data were collected by self-completion questionnaire in both, but the context differed. Results were compared by mode of data collection using two approaches. The first examined differences in results that remained after adjusting the samples for differences in response. The second compared results after using propensity score matching to reduce any differences in sample composition. Results There were no significant differences between the two samples for prevalence of some variables including long-term illness, limiting long-term illness, current rates of smoking, whether participants drank alcohol, and how often they usually drank. However, there were a number of differences, some quite large, between some key measures including: general health, GHQ12 score, portions of fruit and vegetables consumed, levels of physical activity, and, to a lesser extent, smoking consumption, the number of alcohol units reported consumed on the heaviest day of drinking in the last week and perceived social support (among women only. Conclusion Survey mode and context can both affect the responses given. The effect is largest for complex question modules but was also seen for identical self-completion questions. Some data collected by interview and self

  17. Methods and introductory results of the Greek national health and nutrition survey - HYDRIA

    Directory of Open Access Journals (Sweden)

    Georgia Martimianaki

    2018-06-01

    Full Text Available Background:  According to a large prospective cohort study (with baseline examination in the 1990s and smaller studies that followed, the population in Greece has been gradually deprived of the favorable morbidity and mortality indices recorded in the 1960s. The HYDRIA survey conducted in 2013-14 is the first nationally representative survey, which collected data related to the health and nutrition of the population in Greece. Methods: The survey sample consists of 4011 males (47% and females aged 18 years and over. Data collection included interviewer-administered questionnaires on personal characteristics, lifestyle choices, dietary habits and medical history; measurements of somatometry and blood pressure; and, blood drawing. Weighting factors were applied to ensure national representativeness of results. Results: Three out of five adults in Greece reported suffering of a chronic disease, with diabetes mellitus and chronic depression being the more frequent ones among older individuals. The population is also experiencing an overweight/obesity epidemic, since seven out of 10 adults are either overweight or obese. In addition, 40% of the population bears indications of hypertension. Smoking is still common and among women the prevalence was higher in younger age groups. Social disparities were observed in the prevalence of chronic diseases and mortality risk factors (hypertension, obesity, impaired lipid profile and high blood glucose levels. Conclusion: Excess body weight, hypertension, the smoking habit and the population’s limited physical activity are the predominant challenges that public health officials have to deal with in formulating policies and designing actions for the population in Greece.

  18. Inverse probability weighting and doubly robust methods in correcting the effects of non-response in the reimbursed medication and self-reported turnout estimates in the ATH survey.

    Science.gov (United States)

    Härkänen, Tommi; Kaikkonen, Risto; Virtala, Esa; Koskinen, Seppo

    2014-11-06

    To assess the nonresponse rates in a questionnaire survey with respect to administrative register data, and to correct the bias statistically. The Finnish Regional Health and Well-being Study (ATH) in 2010 was based on a national sample and several regional samples. Missing data analysis was based on socio-demographic register data covering the whole sample. Inverse probability weighting (IPW) and doubly robust (DR) methods were estimated using the logistic regression model, which was selected using the Bayesian information criteria. The crude, weighted and true self-reported turnout in the 2008 municipal election and prevalences of entitlements to specially reimbursed medication, and the crude and weighted body mass index (BMI) means were compared. The IPW method appeared to remove a relatively large proportion of the bias compared to the crude prevalence estimates of the turnout and the entitlements to specially reimbursed medication. Several demographic factors were shown to be associated with missing data, but few interactions were found. Our results suggest that the IPW method can improve the accuracy of results of a population survey, and the model selection provides insight into the structure of missing data. However, health-related missing data mechanisms are beyond the scope of statistical methods, which mainly rely on socio-demographic information to correct the results.

  19. Using Electronic Surveys: Advice from Survey Professionals.

    Directory of Open Access Journals (Sweden)

    David M. Shannon

    2002-01-01

    Full Text Available The study reports the perceptions and recommendations of sixty-two experienced survey..researchers from the American Educational Research Association regarding the use of..electronic surveys. The most positive aspects cited for the use of electronic surveys were..reduction of costs (i.e., postage, phone charges, the use of electronic mail for pre-notification or..follow-up purposes, and the compatibility of data with existing software programs. These..professionals expressed limitations in using electronic surveys pertaining to the limited..sampling frame as well as issues of confidentiality, privacy, and the credibility of the sample...They advised that electronic surveys designed with the varied technological background and..capabilities of the respondent in mind, follow sound principles of survey construction, and be..administered to pre-notified, targeted populations with published email addresses.

  20. Universal nucleic acids sample preparation method for cells, spores and their mixture

    Science.gov (United States)

    Bavykin, Sergei [Darien, IL

    2011-01-18

    The present invention relates to a method for extracting nucleic acids from biological samples. More specifically the invention relates to a universal method for extracting nucleic acids from unidentified biological samples. An advantage of the presently invented method is its ability to effectively and efficiently extract nucleic acids from a variety of different cell types including but not limited to prokaryotic or eukaryotic cells and/or recalcitrant organisms (i.e. spores). Unlike prior art methods which are focused on extracting nucleic acids from vegetative cell or spores, the present invention effectively extracts nucleic acids from spores, multiple cell types or mixtures thereof using a single method. Important that the invented method has demonstrated an ability to extract nucleic acids from spores and vegetative bacterial cells with similar levels effectiveness. The invented method employs a multi-step protocol which erodes the cell structure of the biological sample, isolates, labels, fragments nucleic acids and purifies labeled samples from the excess of dye.

  1. Investigation of Six Geological Samples From Wady Sitra Eastern Desert - Egypt Using K0 Neutron Activation Method

    International Nuclear Information System (INIS)

    Soliman, N.F.; Ashmawy, L.S.; Walley El-Dine, N.; Sroor, A.; Mohamed, T.El.

    2010-01-01

    k 0 - Neutron Activation Analysis (k 0 -NAA) is applied to investigate six geological samples collected from Wady Sitra at Eastern desert of Egypt during the survey of gold presence in this area. The samples together with a group of standard (Mo, Fe, Sb and W) are irradiated for 3 hours in one of the inner irradiation site of the Second Egyptian Training and Research Reactor (ETRR-2) operating at power of 19 MW. Mo, Fe and Sb are used to measure the neutron spectrum parameters α(epithermal non-ideality factor) and f (the thermal to epithermal flux ratio) while W is used to test the obtained results. The α( and f parameters are measured using the so-called bare triple monitor method and the obtained results was found to be f = 17.5 ± 0.35 and α(= 0.03±0.002. A Fortran computer program is designed and used to calculate the values of Q 0 (α)for the analyzed elements . The concentration values of 25 elements in the present rock samples have been presented

  2. Representative mass reduction in sampling

    DEFF Research Database (Denmark)

    Petersen, Lars; Esbensen, Harry Kim; Dahl, Casper Kierulf

    2004-01-01

    We here present a comprehensive survey of current mass reduction principles and hardware available in the current market. We conduct a rigorous comparison study of the performance of 17 field and/or laboratory instruments or methods which are quantitatively characterized (and ranked) for accuracy...... dividers, the Boerner Divider, the ??spoon method??, alternate/fractional shoveling and grab sampling. Only devices based on riffle splitting principles (static or rotational) passes the ultimate representativity test (with minor, but significant relative differences). Grab sampling, the overwhelmingly...... most often used mass reduction method, performs appallingly?its use must be discontinued (with the singular exception for completely homogenized fine powders). Only proper mass reduction (i.e. carried out in complete compliance with all appropriate design principles, maintenance and cleaning rules) can...

  3. Dark Energy Survey Year 1 Results: Galaxy Sample for BAO Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Crocce, M.; et al.

    2017-12-17

    We define and characterise a sample of 1.3 million galaxies extracted from the first year of Dark Energy Survey data, optimised to measure Baryon Acoustic Oscillations in the presence of significant redshift uncertainties. The sample is dominated by luminous red galaxies located at redshifts $z \\gtrsim 0.6$. We define the exact selection using color and magnitude cuts that balance the need of high number densities and small photometric redshift uncertainties, using the corresponding forecasted BAO distance error as a figure-of-merit in the process. The typical photo-$z$ uncertainty varies from $2.3\\%$ to $3.6\\%$ (in units of 1+$z$) from $z=0.6$ to $1$, with number densities from $200$ to $130$ galaxies per deg$^2$ in tomographic bins of width $\\Delta z = 0.1$. Next we summarise the validation of the photometric redshift estimation. We characterise and mitigate observational systematics including stellar contamination, and show that the clustering on large scales is robust in front of those contaminants. We show that the clustering signal in the auto-correlations and cross-correlations is generally consistent with theoretical models, which serves as an additional test of the redshift distributions.

  4. Fluidics platform and method for sample preparation and analysis

    Science.gov (United States)

    Benner, W. Henry; Dzenitis, John M.; Bennet, William J.; Baker, Brian R.

    2014-08-19

    Herein provided are fluidics platform and method for sample preparation and analysis. The fluidics platform is capable of analyzing DNA from blood samples using amplification assays such as polymerase-chain-reaction assays and loop-mediated-isothermal-amplification assays. The fluidics platform can also be used for other types of assays and analyzes. In some embodiments, a sample in a sealed tube can be inserted directly. The following isolation, detection, and analyzes can be performed without a user's intervention. The disclosed platform may also comprises a sample preparation system with a magnetic actuator, a heater, and an air-drying mechanism, and fluid manipulation processes for extraction, washing, elution, assay assembly, assay detection, and cleaning after reactions and between samples.

  5. A Delphi Method Analysis to Create an Emergency Medicine Educational Patient Satisfaction Survey

    Directory of Open Access Journals (Sweden)

    Kory S. London

    2015-12-01

    Full Text Available Introduction: Feedback on patient satisfaction (PS as a means to monitor and improve performance in patient communication is lacking in residency training. A physician’s promotion, compensation and job satisfaction may be impacted by his individual PS scores, once he is in practice. Many communication and satisfaction surveys exist but none focus on the emergency department setting for educational purposes. The goal of this project was to create an emergency medicine-based educational PS survey with strong evidence for content validity. Methods: We used the Delphi Method (DM to obtain expert opinion via an iterative process of surveying. Questions were mined from four PS surveys as well as from group suggestion. The DM analysis determined the structure, content and appropriate use of the tool. The group used four-point Likert-type scales and Lynn’s criteria for content validity to determine relevant questions from the stated goals. Results: Twelve recruited experts participated in a series of seven surveys to achieve consensus. A 10-question, single-page survey with an additional page of qualitative questions and demographic questions was selected. Thirty one questions were judged to be relevant from an original 48-question list. Of these, the final 10 questions were chosen. Response rates for individual survey items was 99.5%. Conclusion: The DM produced a consensus survey with content validity evidence. Future work will be needed to obtain evidence for response process, internal structure and construct validity.

  6. Two media method for linear attenuation coefficient determination of irregular soil samples

    International Nuclear Information System (INIS)

    Vici, Carlos Henrique Georges

    2004-01-01

    In several situations of nuclear applications, the knowledge of gamma-ray linear attenuation coefficient for irregular samples is necessary, such as in soil physics and geology. This work presents the validation of a methodology for the determination of the linear attenuation coefficient (μ) of irregular shape samples, in such a way that it is not necessary to know the thickness of the considered sample. With this methodology irregular soil samples (undeformed field samples) from Londrina region, north of Parana were studied. It was employed the two media method for the μ determination. It consists of the μ determination through the measurement of a gamma-ray beam attenuation by the sample sequentially immersed in two different media, with known and appropriately chosen attenuation coefficients. For comparison, the theoretical value of μ was calculated by the product of the mass attenuation coefficient, obtained by the WinXcom code, and the measured value of the density sample. This software employs the chemical composition of the samples and supplies a table of the mass attenuation coefficients versus the photon energy. To verify the validity of the two media method, compared with the simple gamma ray transmission method, regular pome stone samples were used. With these results for the attenuation coefficients and their respective deviations, it was possible to compare the two methods. In this way we concluded that the two media method is a good tool for the determination of the linear attenuation coefficient of irregular materials, particularly in the study of soils samples. (author)

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

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  8. Preparing investigation of methods for surveying tree seed demands among farmers in Tanzania

    DEFF Research Database (Denmark)

    Aabæk, Anders

    Insufficient seed supplies is often a major constraint on tree planting activities in developing countries. A central problem is to assess the actual demands for tree seed. This report shall, as a part of a PhD-study, prepare an investigation of different methods for surveying tree seed demands...... and preferences among private farmers in Tanzania. A framework for investigating seed demand and supply is outlined. The role of a national tree seed project in a seed supply sector is discussed and data requirements for strategy on seed procurement and tree improvement are outlined. Earlier surveys on seed...... demand pattern in Tanzania, Uganda and Nicaragua are discussed and a choice of strategy for an extensive survey of seed demand and supply in Tanzania is made. Different data collection methods and tools, e.g. quantitative and qualitative surveys and rapid rural appraisals, are described in detail...

  9. [Sample preparation methods for chromatographic analysis of organic components in atmospheric particulate matter].

    Science.gov (United States)

    Hao, Liang; Wu, Dapeng; Guan, Yafeng

    2014-09-01

    The determination of organic composition in atmospheric particulate matter (PM) is of great importance in understanding how PM affects human health, environment, climate, and ecosystem. Organic components are also the scientific basis for emission source tracking, PM regulation and risk management. Therefore, the molecular characterization of the organic fraction of PM has become one of the priority research issues in the field of environmental analysis. Due to the extreme complexity of PM samples, chromatographic methods have been the chief selection. The common procedure for the analysis of organic components in PM includes several steps: sample collection on the fiber filters, sample preparation (transform the sample into a form suitable for chromatographic analysis), analysis by chromatographic methods. Among these steps, the sample preparation methods will largely determine the throughput and the data quality. Solvent extraction methods followed by sample pretreatment (e. g. pre-separation, derivatization, pre-concentration) have long been used for PM sample analysis, and thermal desorption methods have also mainly focused on the non-polar organic component analysis in PM. In this paper, the sample preparation methods prior to chromatographic analysis of organic components in PM are reviewed comprehensively, and the corresponding merits and limitations of each method are also briefly discussed.

  10. Using the Superpopulation Model for Imputations and Variance Computation in Survey Sampling

    Directory of Open Access Journals (Sweden)

    Petr Novák

    2012-03-01

    Full Text Available This study is aimed at variance computation techniques for estimates of population characteristics based on survey sampling and imputation. We use the superpopulation regression model, which means that the target variable values for each statistical unit are treated as random realizations of a linear regression model with weighted variance. We focus on regression models with one auxiliary variable and no intercept, which have many applications and straightforward interpretation in business statistics. Furthermore, we deal with caseswhere the estimates are not independent and thus the covariance must be computed. We also consider chained regression models with auxiliary variables as random variables instead of constants.

  11. Sampling methods for amphibians in streams in the Pacific Northwest.

    Science.gov (United States)

    R. Bruce Bury; Paul Stephen. Corn

    1991-01-01

    Methods describing how to sample aquatic and semiaquatic amphibians in small streams and headwater habitats in the Pacific Northwest are presented. We developed a technique that samples 10-meter stretches of selected streams, which was adequate to detect presence or absence of amphibian species and provided sample sizes statistically sufficient to compare abundance of...

  12. Evaluation of sampling methods for Bacillus spore-contaminated HVAC filters

    OpenAIRE

    Calfee, M. Worth; Rose, Laura J.; Tufts, Jenia; Morse, Stephen; Clayton, Matt; Touati, Abderrahmane; Griffin-Gatchalian, Nicole; Slone, Christina; McSweeney, Neal

    2013-01-01

    The objective of this study was to compare an extraction-based sampling method to two vacuum-based sampling methods (vacuum sock and 37 mm cassette filter) with regards to their ability to recover Bacillus atrophaeus spores (surrogate for Bacillus anthracis) from pleated heating, ventilation, and air conditioning (HVAC) filters that are typically found in commercial and residential buildings. Electrostatic and mechanical HVAC filters were tested, both without and after loading with dust to 50...

  13. Statistical properties of mean stand biomass estimators in a LIDAR-based double sampling forest survey design.

    Science.gov (United States)

    H.E. Anderson; J. Breidenbach

    2007-01-01

    Airborne laser scanning (LIDAR) can be a valuable tool in double-sampling forest survey designs. LIDAR-derived forest structure metrics are often highly correlated with important forest inventory variables, such as mean stand biomass, and LIDAR-based synthetic regression estimators have the potential to be highly efficient compared to single-stage estimators, which...

  14. Sampling Methods and the Accredited Population in Athletic Training Education Research

    Science.gov (United States)

    Carr, W. David; Volberding, Jennifer

    2009-01-01

    Context: We describe methods of sampling the widely-studied, yet poorly defined, population of accredited athletic training education programs (ATEPs). Objective: There are two purposes to this study; first to describe the incidence and types of sampling methods used in athletic training education research, and second to clearly define the…

  15. Comparing Coral Reef Survey Methods. Unesco Reports in Marine Science No. 21 Report of a Regional Unesco/UNEP Workshop on Coral Reef Survey Management and Assessment Methods in Asia and the Pacific (Phuket, Thailand, December 13-17, 1982).

    Science.gov (United States)

    United Nations Educational, Scientific, and Cultural Organization, Paris (France). Div. of Marine Sciences.

    This report includes nine papers prepared for a workshop on coral reef survey management and assessment methods in Asia and the Pacific. The papers are: "A Contrast in Methodologies between Surveying and Testing" (Charles Birkeland); "Coral Reef Survey Methods in the Andaman Sea" (Hansa Chansang); "A Review of Coral Reef…

  16. The former Semipalatinsk Test Site survey by field γ-spectrometry method

    International Nuclear Information System (INIS)

    Pakhomov, S.A.; Dubasov, Yu.V.; Biryukov, E.I.; Gavrilin, S.S.; Ilyin, L.I.

    2001-01-01

    Full text: Field γ-spectrometry method is the most productive method of getting an information on gamma-irradiating radionuclides contents in objects under survey. For many years the Radium Institute was the most active participant of works on radiation survey of the Semipalatinsk Test Site, field γ-spectrometry method including. In field γ-spectrometry method realization the existence of corresponding apparatus, and methodic software is supposed to be allowing to carry out both measurement, recording of γ-spectrometry energetic characteristics in field conditions and final treatment (using corresponding physical models) ensuring obtaining the information on radionuclides' contents. Different variants of such apparatus were developed and made at the Radium Institute. Under conditions of complex spectral structure and high intensity existence a portable variant of Ge(Li)-detector spectrometer fed by alkaline accumulators and allowing to record a spectrum at high load was elaborated. For walk γ-survey in common with the University two variants of portable spectrometers 'Skif-3' were elaborated: one of them with a standard scintillation detector on the base of Nal(Ti) crystal, having the size of 63x63 mm, and the other is an 'X-ray' detector of large dimension on the base of CsI crystal with a diameter of 165 mm, designated for soft gamma-irradiation registration, 241 Am including. During 8 hours of independent works 'Skif-3' is able to record into internal memory up to 100 spectra with an exposure up to 9999 s. At 10 min exposure in its sensitivity of 241 Am finding (10 Bq/kg) a spectrometer 'Skif-3' excels a portable spectrometer 'InSpector' (Canberra) working with the exposure of 1 hour. For automobile measurements a car spectrometer was elaborated fed. from car board supply and having four detectors based on NaI crystals with the dimensions 200x110 mm and total volume of about 121. For express treatment of a 'Skif-3' spectrometer scintillation spectra special

  17. Method and apparatus for continuous sampling

    International Nuclear Information System (INIS)

    Marcussen, C.

    1982-01-01

    An apparatus and method for continuously sampling a pulverous material flow includes means for extracting a representative subflow from a pulverous material flow. A screw conveyor is provided to cause the extracted subflow to be pushed upwardly through a duct to an overflow. Means for transmitting a radiation beam transversely to the subflow in the duct, and means for sensing the transmitted beam through opposite pairs of windows in the duct are provided to measure the concentration of one or more constituents in the subflow. (author)

  18. Geochemical reanalysis of historical U.S. Geological Survey sediment samples from the northeastern Alaska Range, Healy, Mount Hayes, Nabesna, and Tanacross quadrangles, Alaska

    Science.gov (United States)

    Werdon, Melanie B.; Granitto, Matthew; Azain, Jaime S.

    2015-01-01

    The State of Alaska’s Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska’s statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. As part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential. The USGS is also undertaking SCM-related geologic studies in Alaska through the federally funded Alaska Critical Minerals cooperative project. DGGS and USGS share the goal of evaluating Alaska’s strategic and critical minerals potential and together created a Letter of Agreement (signed December 2012) and a supplementary Technical Assistance Agreement (#14CMTAA143458) to facilitate the two agencies’ cooperative work. Under these agreements, DGGS contracted the USGS in Denver to reanalyze historical USGS sediment samples from Alaska. For this report, DGGS funded reanalysis of 670 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from the northeastern Alaska Range, in the Healy, Mount Hayes, Nabesna, and Tanacross quadrangles, Alaska (fig. 1). The USGS was responsible for sample retrieval from the National Geochemical Sample Archive (NGSA) in Denver, Colorado through the final quality assurance/quality control (QA/QC) of the geochemical analyses obtained through the USGS contract lab. The new geochemical data are published in this report as a coauthored DGGS report, and will be incorporated into the statewide geochemical

  19. Survey of radioactive contamination of foodstuffs

    International Nuclear Information System (INIS)

    Lee, W. R.; Lee, C. W.; Choi, G. S.; Cho, Y. H.; Kang, M. J.; Cheong, K. H.; Kim, H. R.; Kwak, J. Y.

    2005-11-01

    The purpose of this study is to survey and assess radioactive contamination of foodstuffs in order to reduce the probability of intake of contaminated foodstuffs. Based on survey and assessment, final goal is to improve the public health by radiation protection. Sampled foodstuffs items are collected from the markets : one group are imported foodstuffs and the other group are domestic foodstuffs producted around nuclear facilities. After pretreatments such as drying, ashing, and homogenization, all samples were analyzed by gamma spectrometer system. The 137 Cs radionuclide was only measured among the regulation radionuclides ( 137 Cs, 134 Cs, 131 I) of food code. All radionuclides of the domestic foodstuffs collected around nuclear facilities were below Minimum Detectable Activity (MDA). But the activity concentrations of Inonotus obliquus (Chaga mushooms) from Russia ranged up to 171.27 (average value : 36.65) Bq/kg-fresh. In the case of blueberry jam, the radioactivity of 137 Cs is higher than expected value. Other samples are below MDA except some spices. Based on the previous and present results, it should be strengthen to survey for Inontus obliquus (Chaga mushooms), of which the radioactivity shows the range from MDA up to 800.01 Bq/kg-fresh. It should assess the public radiation exposure via food chain because it has the excess provability of the maximum permitted level of food code, which is regulation of KFDA. The development method based on international standard would be used at radioactive analysis as well as education of practical workers and it could be applied as the basis data for amending the analysis method of food code. Our country only surveys gamma emitting radionuclides till now but international organization or foreign countries for example EU survey alpha and beta emitting radionuclides as well as gamma emitting radionuclides. So our country should also research necessity of survey for alpha and beta emitting radionuclides

  20. Like a virgin (mother): analysis of data from a longitudinal, US population representative sample survey

    OpenAIRE

    Herring, Amy H; Attard, Samantha M; Gordon-Larsen, Penny; Joyner, William H; Halpern, Carolyn T

    2013-01-01

    Objective To estimate the incidence of self report of pregnancy without sexual intercourse (virgin pregnancy) and factors related to such reporting, in a population representative group of US adolescents and young adults. Design Longitudinal, population representative sample survey. Setting Nationally representative, multiethnic National Longitudinal Study of Adolescent Health, United States. Participants 7870 women enrolled at wave I (1995) and completing the most recent wave of data collect...