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

PubMed

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.

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

PubMed

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.

Methodological Challenges in Collecting Social and Behavioural Data Regarding the HIV Epidemic among Gay and Other Men Who Have Sex with Men in Australia

PubMed Central

Holt, Martin; de Wit, John; Brown, Graham; Maycock, Bruce; Fairley, Christopher; Prestage, Garrett

2014-01-01

Background Behavioural surveillance and research among gay and other men who have sex with men (GMSM) commonly relies on non-random recruitment approaches. Methodological challenges limit their ability to accurately represent the population of adult GMSM. We compared the social and behavioural profiles of GMSM recruited via venue-based, online, and respondent-driven sampling (RDS) and discussed their utility for behavioural surveillance. Methods Data from four studies were selected to reflect each recruitment method. We compared demographic characteristics and the prevalence of key indicators including sexual and HIV testing practices obtained from samples recruited through different methods, and population estimates from respondent-driven sampling partition analysis. Results Overall, the socio-demographic profile of GMSM was similar across samples, with some differences observed in age and sexual identification. Men recruited through time-location sampling appeared more connected to the gay community, reported a greater number of sexual partners, but engaged in less unprotected anal intercourse with regular (UAIR) or casual partners (UAIC). The RDS sample overestimated the proportion of HIV-positive men and appeared to recruit men with an overall higher number of sexual partners. A single-website survey recruited a sample with characteristics which differed considerably from the population estimates with regards to age, ethnically diversity and behaviour. Data acquired through time-location sampling underestimated the rates of UAIR and UAIC, while RDS and online sampling both generated samples that underestimated UAIR. Simulated composite samples combining recruits from time-location and multi-website online sampling may produce characteristics more consistent with the population estimates, particularly with regards to sexual practices. Conclusion Respondent-driven sampling produced the sample that was most consistent to population estimates, but this methodology is complex and logistically demanding. Time-location and online recruitment are more cost-effective and easier to implement; using these approaches in combination may offer the potential to recruit a more representative sample of GMSM. PMID:25409440

Methodological challenges in collecting social and behavioural data regarding the HIV epidemic among gay and other men who have sex with men in Australia.

PubMed

Zablotska, Iryna B; Frankland, Andrew; Holt, Martin; de Wit, John; Brown, Graham; Maycock, Bruce; Fairley, Christopher; Prestage, Garrett

2014-01-01

Behavioural surveillance and research among gay and other men who have sex with men (GMSM) commonly relies on non-random recruitment approaches. Methodological challenges limit their ability to accurately represent the population of adult GMSM. We compared the social and behavioural profiles of GMSM recruited via venue-based, online, and respondent-driven sampling (RDS) and discussed their utility for behavioural surveillance. Data from four studies were selected to reflect each recruitment method. We compared demographic characteristics and the prevalence of key indicators including sexual and HIV testing practices obtained from samples recruited through different methods, and population estimates from respondent-driven sampling partition analysis. Overall, the socio-demographic profile of GMSM was similar across samples, with some differences observed in age and sexual identification. Men recruited through time-location sampling appeared more connected to the gay community, reported a greater number of sexual partners, but engaged in less unprotected anal intercourse with regular (UAIR) or casual partners (UAIC). The RDS sample overestimated the proportion of HIV-positive men and appeared to recruit men with an overall higher number of sexual partners. A single-website survey recruited a sample with characteristics which differed considerably from the population estimates with regards to age, ethnically diversity and behaviour. Data acquired through time-location sampling underestimated the rates of UAIR and UAIC, while RDS and online sampling both generated samples that underestimated UAIR. Simulated composite samples combining recruits from time-location and multi-website online sampling may produce characteristics more consistent with the population estimates, particularly with regards to sexual practices. Respondent-driven sampling produced the sample that was most consistent to population estimates, but this methodology is complex and logistically demanding. Time-location and online recruitment are more cost-effective and easier to implement; using these approaches in combination may offer the potential to recruit a more representative sample of GMSM.

A Web 2.0 and Epidemiology Mash-Up: Using respondent-driven sampling in combination with social network site recruitment to reach young transwomen

PubMed Central

Arayasirikul, Sean; Chen, Yea-Hung; Jin, Harry; Wilson, Erin

2015-01-01

Respondent-driven sampling (RDS) peer referral has been proven to be an effective recruitment method for hard-to-reach populations; however, its application in diverse populations is limited. Recruitment occurred in two phases: RDS-only followed by development and implementation of an online social network strategy in combination with RDS peer referral (RDS+SNS). Compared to RDS-only, RDS+SNS reached a sample that was younger (χ2=9.19, P = .03), more likely to identify with a non-binary gender identity (χ2=10.4247, P = .03), with less housing instability (50.5% vs. 68.6%, χ2=9.0038, P = .002) and less sex work (19.7% vs. 31.4%, χ2=5.0798, P = .02). Additionally, we describe lessons learned as a result of implementing our online social network strategy. Our findings underscore the importance of integrating Internet-driven strategies to meet challenges in sample diversity and recruitment of young transwomen. PMID:26499337

The efficacy of respondent-driven sampling for the health assessment of minority populations.

PubMed

Badowski, Grazyna; Somera, Lilnabeth P; Simsiman, Brayan; Lee, Hye-Ryeon; Cassel, Kevin; Yamanaka, Alisha; Ren, JunHao

2017-10-01

Respondent driven sampling (RDS) is a relatively new network sampling technique typically employed for hard-to-reach populations. Like snowball sampling, initial respondents or "seeds" recruit additional respondents from their network of friends. Under certain assumptions, the method promises to produce a sample independent from the biases that may have been introduced by the non-random choice of "seeds." We conducted a survey on health communication in Guam's general population using the RDS method, the first survey that has utilized this methodology in Guam. It was conducted in hopes of identifying a cost-efficient non-probability sampling strategy that could generate reasonable population estimates for both minority and general populations. RDS data was collected in Guam in 2013 (n=511) and population estimates were compared with 2012 BRFSS data (n=2031) and the 2010 census data. The estimates were calculated using the unweighted RDS sample and the weighted sample using RDS inference methods and compared with known population characteristics. The sample size was reached in 23days, providing evidence that the RDS method is a viable, cost-effective data collection method, which can provide reasonable population estimates. However, the results also suggest that the RDS inference methods used to reduce bias, based on self-reported estimates of network sizes, may not always work. Caution is needed when interpreting RDS study findings. For a more diverse sample, data collection should not be conducted in just one location. Fewer questions about network estimates should be asked, and more careful consideration should be given to the kind of incentives offered to participants. Copyright © 2017. Published by Elsevier Ltd.

[Respondent-Driven Sampling: a new sampling method to study visible and hidden populations].

PubMed

Mantecón, Alejandro; Juan, Montse; Calafat, Amador; Becoña, Elisardo; Román, Encarna

2008-01-01

The paper introduces a variant of chain-referral sampling: respondent-driven sampling (RDS). This sampling method shows that methods based on network analysis can be combined with the statistical validity of standard probability sampling methods. In this sense, RDS appears to be a mathematical improvement of snowball sampling oriented to the study of hidden populations. However, we try to prove its validity with populations that are not within a sampling frame but can nonetheless be contacted without difficulty. The basics of RDS are explained through our research on young people (aged 14 to 25) who go clubbing, consume alcohol and other drugs, and have sex. Fieldwork was carried out between May and July 2007 in three Spanish regions: Baleares, Galicia and Comunidad Valenciana. The presentation of the study shows the utility of this type of sampling when the population is accessible but there is a difficulty deriving from the lack of a sampling frame. However, the sample obtained is not a random representative one in statistical terms of the target population. It must be acknowledged that the final sample is representative of a 'pseudo-population' that approximates to the target population but is not identical to it.

Sampling Methodologies for Epidemiologic Surveillance of Men Who Have Sex with Men and Transgender Women in Latin America: An Empiric Comparison of Convenience Sampling, Time Space Sampling, and Respondent Driven Sampling

PubMed Central

Clark, J. L.; Konda, K. A.; Silva-Santisteban, A.; Peinado, J.; Lama, J. R.; Kusunoki, L.; Perez-Brumer, A.; Pun, M.; Cabello, R.; Sebastian, J. L.; Suarez-Ognio, L.; Sanchez, J.

2014-01-01

Alternatives to convenience sampling (CS) are needed for HIV/STI surveillance of most-at-risk populations in Latin America. We compared CS, time space sampling (TSS), and respondent driven sampling (RDS) for recruitment of men who have sex with men (MSM) and transgender women (TW) in Lima, Peru. During concurrent 60-day periods from June–August, 2011, we recruited MSM/TW for epidemiologic surveillance using CS, TSS, and RDS. A total of 748 participants were recruited through CS, 233 through TSS, and 127 through RDS. The TSS sample included the largest proportion of TW (30.7 %) and the lowest percentage of subjects who had previously participated in HIV/STI research (14.9 %). The prevalence of newly diagnosed HIV infection, according to participants’ self-reported previous HIV diagnosis, was highest among TSS recruits (17.9 %) compared with RDS (12.6 %) and CS (10.2 %). TSS identified diverse populations of MSM/TW with higher prevalences of HIV/STIs not accessed by other methods. PMID:24362754

Sampling methodologies for epidemiologic surveillance of men who have sex with men and transgender women in Latin America: an empiric comparison of convenience sampling, time space sampling, and respondent driven sampling.

PubMed

Clark, J L; Konda, K A; Silva-Santisteban, A; Peinado, J; Lama, J R; Kusunoki, L; Perez-Brumer, A; Pun, M; Cabello, R; Sebastian, J L; Suarez-Ognio, L; Sanchez, J

2014-12-01

Alternatives to convenience sampling (CS) are needed for HIV/STI surveillance of most-at-risk populations in Latin America. We compared CS, time space sampling (TSS), and respondent driven sampling (RDS) for recruitment of men who have sex with men (MSM) and transgender women (TW) in Lima, Peru. During concurrent 60-day periods from June-August, 2011, we recruited MSM/TW for epidemiologic surveillance using CS, TSS, and RDS. A total of 748 participants were recruited through CS, 233 through TSS, and 127 through RDS. The TSS sample included the largest proportion of TW (30.7 %) and the lowest percentage of subjects who had previously participated in HIV/STI research (14.9 %). The prevalence of newly diagnosed HIV infection, according to participants' self-reported previous HIV diagnosis, was highest among TSS recruits (17.9 %) compared with RDS (12.6 %) and CS (10.2 %). TSS identified diverse populations of MSM/TW with higher prevalences of HIV/STIs not accessed by other methods.

Estimating the size of hidden populations using respondent-driven sampling data: Case examples from Morocco

PubMed Central

Johnston, Lisa G; McLaughlin, Katherine R; Rhilani, Houssine El; Latifi, Amina; Toufik, Abdalla; Bennani, Aziza; Alami, Kamal; Elomari, Boutaina; Handcock, Mark S

2015-01-01

Background Respondent-driven sampling is used worldwide to estimate the population prevalence of characteristics such as HIV/AIDS and associated risk factors in hard-to-reach populations. Estimating the total size of these populations is of great interest to national and international organizations, however reliable measures of population size often do not exist. Methods Successive Sampling-Population Size Estimation (SS-PSE) along with network size imputation allows population size estimates to be made without relying on separate studies or additional data (as in network scale-up, multiplier and capture-recapture methods), which may be biased. Results Ten population size estimates were calculated for people who inject drugs, female sex workers, men who have sex with other men, and migrants from sub-Sahara Africa in six different cities in Morocco. SS-PSE estimates fell within or very close to the likely values provided by experts and the estimates from previous studies using other methods. Conclusions SS-PSE is an effective method for estimating the size of hard-to-reach populations that leverages important information within respondent-driven sampling studies. The addition of a network size imputation method helps to smooth network sizes allowing for more accurate results. However, caution should be used particularly when there is reason to believe that clustered subgroups may exist within the population of interest or when the sample size is small in relation to the population. PMID:26258908

A Web 2.0 and Epidemiology Mash-Up: Using Respondent-Driven Sampling in Combination with Social Network Site Recruitment to Reach Young Transwomen.

PubMed

Arayasirikul, Sean; Chen, Yea-Hung; Jin, Harry; Wilson, Erin

2016-06-01

Respondent-driven sampling (RDS) peer referral has been proven to be an effective recruitment method for hard-to-reach populations; however, its application in diverse populations is limited. Recruitment occurred in two phases: RDS-only followed by development and implementation of an online social network strategy in combination with RDS peer referral (RDS + SNS). Compared to RDS-only, RDS + SNS reached a sample that was younger (χ(2) = 9.19, P = .03), more likely to identify with a non-binary gender identity (χ(2) = 10.4247, P = .03), with less housing instability (50.5 vs. 68.6 %, χ(2) = 9.0038, P = .002) and less sex work (19.7 vs. 31.4 %, χ(2) = 5.0798, P = .02). Additionally, we describe lessons learned as a result of implementing our online social network strategy. Our findings underscore the importance of integrating Internet-driven strategies to meet challenges in sample diversity and recruitment of young transwomen.

Estimating uncertainty in respondent-driven sampling using a tree bootstrap method.

PubMed

Baraff, Aaron J; McCormick, Tyler H; Raftery, Adrian E

2016-12-20

Respondent-driven sampling (RDS) is a network-based form of chain-referral sampling used to estimate attributes of populations that are difficult to access using standard survey tools. Although it has grown quickly in popularity since its introduction, the statistical properties of RDS estimates remain elusive. In particular, the sampling variability of these estimates has been shown to be much higher than previously acknowledged, and even methods designed to account for RDS result in misleadingly narrow confidence intervals. In this paper, we introduce a tree bootstrap method for estimating uncertainty in RDS estimates based on resampling recruitment trees. We use simulations from known social networks to show that the tree bootstrap method not only outperforms existing methods but also captures the high variability of RDS, even in extreme cases with high design effects. We also apply the method to data from injecting drug users in Ukraine. Unlike other methods, the tree bootstrap depends only on the structure of the sampled recruitment trees, not on the attributes being measured on the respondents, so correlations between attributes can be estimated as well as variability. Our results suggest that it is possible to accurately assess the high level of uncertainty inherent in RDS.

Efficacy of convenience sampling through the internet versus respondent driven sampling among males who have sex with males in Tallinn and Harju County, Estonia: challenges reaching a hidden population.

PubMed

Johnston, Lisa Grazina; Trummal, Aire; Lohmus, Liilia; Ravalepik, Ardi

2009-09-01

This paper examines challenges obtaining representative samples of males who have sex with males (MSM) in Estonia and provides descriptive HIV behavioral data gathered from four cross-sectional surveys; three using the internet, and one using respondent driven sampling (RDS) to recruit MSM in Tallinn and Harju County. Estonian MSM were sampled between March and May in 2004 (n=193), August and November in 2005 (n=146) and September and December in 2007 (n=238) using internet websites. MSM in Tallinn and Harju County were sampled between April and June in 2007 (n=59) using RDS. Recruitment of MSM using RDS did not acquire the calculated sample size. The RDS study reached a less diverse group of MSM than did the internet studies which recruited a larger proportion of MSM who were older, bisexual, having female sexual partners during the last six months, and unlikely to have been tested for HIV. The findings and observations presented in this paper could inform researchers in Estonia, and the region, about the efficacy of and socio-cultural challenges to sampling MSM to collect HIV biological and/or behavioral data.

Consistently Low Prevalence of Syphilis among Female Sex Workers in Jinan, China: Findings from Two Consecutive Respondent Driven Sampling Surveys

PubMed Central

Liao, Meizhen; Nie, Xijuan; Pan, Rongjian; Wang, Chuangxin; Ruan, Shiman; Zhang, Changqing; Kang, Dianming; Fu, Jihua; Qian, Yuesheng; Tao, Xiaorun; Zhao, Jinkou

2012-01-01

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. PMID:22539944

Utilization of respondent-driven sampling among a population of child workers in the diamond-mining sector of Sierra Leone.

PubMed

Bjørkhaug, I; Hatløy, A

2009-01-01

This article describes the implementation of respondent driven sampling (RDS) in a study conducted in Kono District, Sierra Leone. RDS was used to identify children, under the age of 18 years old, working in the diamond sector of Sierra Leone. This includes children working directly as diamond miners as well as children working in the informal sector connected to the diamond field. The article seeks to postulate that RDS is a suitable method for a rapid approach to a population that is unidentified in size and demonstrate how RDS can reach a study population within a limited period.

Assessing respondent-driven sampling.

PubMed

Goel, Sharad; Salganik, Matthew J

2010-04-13

Respondent-driven sampling (RDS) is a network-based technique for estimating traits in hard-to-reach populations, for example, the prevalence of HIV among drug injectors. In recent years RDS has been used in more than 120 studies in more than 20 countries and by leading public health organizations, including the Centers for Disease Control and Prevention in the United States. Despite the widespread use and growing popularity of RDS, there has been little empirical validation of the methodology. Here we investigate the performance of RDS by simulating sampling from 85 known, network populations. Across a variety of traits we find that RDS is substantially less accurate than generally acknowledged and that reported RDS confidence intervals are misleadingly narrow. Moreover, because we model a best-case scenario in which the theoretical RDS sampling assumptions hold exactly, it is unlikely that RDS performs any better in practice than in our simulations. Notably, the poor performance of RDS is driven not by the bias but by the high variance of estimates, a possibility that had been largely overlooked in the RDS literature. Given the consistency of our results across networks and our generous sampling conditions, we conclude that RDS as currently practiced may not be suitable for key aspects of public health surveillance where it is now extensively applied.

Assessing respondent-driven sampling

PubMed Central

Goel, Sharad; Salganik, Matthew J.

2010-01-01

Respondent-driven sampling (RDS) is a network-based technique for estimating traits in hard-to-reach populations, for example, the prevalence of HIV among drug injectors. In recent years RDS has been used in more than 120 studies in more than 20 countries and by leading public health organizations, including the Centers for Disease Control and Prevention in the United States. Despite the widespread use and growing popularity of RDS, there has been little empirical validation of the methodology. Here we investigate the performance of RDS by simulating sampling from 85 known, network populations. Across a variety of traits we find that RDS is substantially less accurate than generally acknowledged and that reported RDS confidence intervals are misleadingly narrow. Moreover, because we model a best-case scenario in which the theoretical RDS sampling assumptions hold exactly, it is unlikely that RDS performs any better in practice than in our simulations. Notably, the poor performance of RDS is driven not by the bias but by the high variance of estimates, a possibility that had been largely overlooked in the RDS literature. Given the consistency of our results across networks and our generous sampling conditions, we conclude that RDS as currently practiced may not be suitable for key aspects of public health surveillance where it is now extensively applied. PMID:20351258

Authorship Correction: Sampling Key Populations for HIV Surveillance: Results From Eight Cross-Sectional Studies Using Respondent-Driven Sampling and Venue-Based Snowball Sampling.

PubMed

Rao, Amrita; Stahlman, Shauna; Hargreaves, James; Weir, Sharon; Edwards, Jessie; Rice, Brian; Kochelani, Duncan; Mavimbela, Mpumelelo; Baral, Stefan

2018-01-15

[This corrects the article DOI: 10.2196/publichealth.8116.]. ©Amrita Rao, Shauna Stahlman, James Hargreaves, Sharon Weir, Jessie Edwards, Brian Rice, Duncan Kochelani, Mpumelelo Mavimbela, Stefan Baral. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 15.01.2018.

Social Network Clustering and the Spread of HIV/AIDS Among Persons Who Inject Drugs in 2 Cities in the Philippines.

PubMed

Verdery, Ashton M; Siripong, Nalyn; Pence, Brian W

2017-09-01

The Philippines has seen rapid increases in HIV prevalence among people who inject drugs. We study 2 neighboring cities where a linked HIV epidemic differed in timing of onset and levels of prevalence. In Cebu, prevalence rose rapidly from below 1% to 54% between 2009 and 2011 and remained high through 2013. In nearby Mandaue, HIV remained below 4% through 2011 then rose rapidly to 38% by 2013. We hypothesize that infection prevalence differences in these cities may owe to aspects of social network structure, specifically levels of network clustering. Building on previous research, we hypothesize that higher levels of network clustering are associated with greater epidemic potential. Data were collected with respondent-driven sampling among men who inject drugs in Cebu and Mandaue in 2013. We first examine sample composition using estimators for population means. We then apply new estimators of network clustering in respondent-driven sampling data to examine associations with HIV prevalence. Samples in both cities were comparable in composition by age, education, and injection locations. Dyadic needle-sharing levels were also similar between the 2 cities, but network clustering in the needle-sharing network differed dramatically. We found higher clustering in Cebu than Mandaue, consistent with expectations that higher clustering is associated with faster epidemic spread. This article is the first to apply estimators of network clustering to empirical respondent-driven samples, and it offers suggestive evidence that researchers should pay greater attention to network structure's role in HIV transmission dynamics.

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

PubMed

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.

Using Respondent-Driven Sampling to Recruit Illegal Drug Purchasers to Evaluate a Drug Market Intervention.

PubMed

Ober, Allison J; Sussell, Jesse; Kilmer, Beau; Saunders, Jessica; Heckathorn, Douglas D

2016-04-01

Violent drug markets are not as prominent as they once were in the United States, but they still exist and are associated with significant crime and lower quality of life. The drug market intervention (DMI) is an innovative strategy that uses focused deterrence, community engagement, and incapacitation to reduce crime and disorder associated with these markets. Although studies show that DMI can reduce crime and overt drug activity, one perspective is prominently missing from these evaluations: those who purchase drugs. This study explores the use of respondent-driven sampling (RDS)-a statistical sampling method-to approximate a representative sample of drug users who purchased drugs in a targeted DMI market to gain insight into the effect of a DMI on market dynamics. Using RDS, we recruited individuals who reported hard drug use (crack or powder cocaine, heroin, methamphetamine, or illicit use of prescriptions opioids) in the last month to participate in a survey. The main survey asked about drug use, drug purchasing, and drug market activity before and after DMI; a secondary survey asked about network characteristics and recruitment. Our sample of 212 respondents met key RDS assumptions, suggesting that the characteristics of our weighted sample approximate the characteristics of the drug user network. The weighted estimates for market purchasers are generally valid for inferences about the aggregate population of customers, but a larger sample size is needed to make stronger inferences about the effects of a DMI on drug market activity. © The Author(s) 2016.

Innovative recruitment using online networks: lessons learned from an online study of alcohol and other drug use utilizing a web-based, respondent-driven sampling (webRDS) strategy.

PubMed

Bauermeister, José A; Zimmerman, Marc A; Johns, Michelle M; Glowacki, Pietreck; Stoddard, Sarah; Volz, Erik

2012-09-01

We used a web version of Respondent-Driven Sampling (webRDS) to recruit a sample of young adults (ages 18-24) and examined whether this strategy would result in alcohol and other drug (AOD) prevalence estimates comparable to national estimates (National Survey on Drug Use and Health [NSDUH]). We recruited 22 initial participants (seeds) via Facebook to complete a web survey examining AOD risk correlates. Sequential, incentivized recruitment continued until our desired sample size was achieved. After correcting for webRDS clustering effects, we contrasted our AOD prevalence estimates (past 30 days) to NSDUH estimates by comparing the 95% confidence intervals of prevalence estimates. We found comparable AOD prevalence estimates between our sample and NSDUH for the past 30 days for alcohol, marijuana, cocaine, Ecstasy (3,4-methylenedioxymethamphetamine, or MDMA), and hallucinogens. Cigarette use was lower than NSDUH estimates. WebRDS may be a suitable strategy to recruit young adults online. We discuss the unique strengths and challenges that may be encountered by public health researchers using webRDS methods.

Network Structure and Biased Variance Estimation in Respondent Driven Sampling

PubMed Central

Verdery, Ashton M.; Mouw, Ted; Bauldry, Shawn; Mucha, Peter J.

2015-01-01

This paper explores bias in the estimation of sampling variance in Respondent Driven Sampling (RDS). Prior methodological work on RDS has focused on its problematic assumptions and the biases and inefficiencies of its estimators of the population mean. Nonetheless, researchers have given only slight attention to the topic of estimating sampling variance in RDS, despite the importance of variance estimation for the construction of confidence intervals and hypothesis tests. In this paper, we show that the estimators of RDS sampling variance rely on a critical assumption that the network is First Order Markov (FOM) with respect to the dependent variable of interest. We demonstrate, through intuitive examples, mathematical generalizations, and computational experiments that current RDS variance estimators will always underestimate the population sampling variance of RDS in empirical networks that do not conform to the FOM assumption. Analysis of 215 observed university and school networks from Facebook and Add Health indicates that the FOM assumption is violated in every empirical network we analyze, and that these violations lead to substantially biased RDS estimators of sampling variance. We propose and test two alternative variance estimators that show some promise for reducing biases, but which also illustrate the limits of estimating sampling variance with only partial information on the underlying population social network. PMID:26679927

A simulative comparison of respondent driven sampling with incentivized snowball sampling--the "strudel effect".

PubMed

Gyarmathy, V Anna; Johnston, Lisa G; Caplinskiene, Irma; Caplinskas, Saulius; Latkin, Carl A

2014-02-01

Respondent driven sampling (RDS) and incentivized snowball sampling (ISS) are two sampling methods that are commonly used to reach people who inject drugs (PWID). We generated a set of simulated RDS samples on an actual sociometric ISS sample of PWID in Vilnius, Lithuania ("original sample") to assess if the simulated RDS estimates were statistically significantly different from the original ISS sample prevalences for HIV (9.8%), Hepatitis A (43.6%), Hepatitis B (Anti-HBc 43.9% and HBsAg 3.4%), Hepatitis C (87.5%), syphilis (6.8%) and Chlamydia (8.8%) infections and for selected behavioral risk characteristics. The original sample consisted of a large component of 249 people (83% of the sample) and 13 smaller components with 1-12 individuals. Generally, as long as all seeds were recruited from the large component of the original sample, the simulation samples simply recreated the large component. There were no significant differences between the large component and the entire original sample for the characteristics of interest. Altogether 99.2% of 360 simulation sample point estimates were within the confidence interval of the original prevalence values for the characteristics of interest. When population characteristics are reflected in large network components that dominate the population, RDS and ISS may produce samples that have statistically non-different prevalence values, even though some isolated network components may be under-sampled and/or statistically significantly different from the main groups. This so-called "strudel effect" is discussed in the paper. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

A simulative comparison of respondent driven sampling with incentivized snowball sampling – the “strudel effect”

PubMed Central

Gyarmathy, V. Anna; Johnston, Lisa G.; Caplinskiene, Irma; Caplinskas, Saulius; Latkin, Carl A.

2014-01-01

Background Respondent driven sampling (RDS) and Incentivized Snowball Sampling (ISS) are two sampling methods that are commonly used to reach people who inject drugs (PWID). Methods We generated a set of simulated RDS samples on an actual sociometric ISS sample of PWID in Vilnius, Lithuania (“original sample”) to assess if the simulated RDS estimates were statistically significantly different from the original ISS sample prevalences for HIV (9.8%), Hepatitis A (43.6%), Hepatitis B (Anti-HBc 43.9% and HBsAg 3.4%), Hepatitis C (87.5%), syphilis (6.8%) and Chlamydia (8.8%) infections and for selected behavioral risk characteristics. Results The original sample consisted of a large component of 249 people (83% of the sample) and 13 smaller components with 1 to 12 individuals. Generally, as long as all seeds were recruited from the large component of the original sample, the simulation samples simply recreated the large component. There were no significant differences between the large component and the entire original sample for the characteristics of interest. Altogether 99.2% of 360 simulation sample point estimates were within the confidence interval of the original prevalence values for the characteristics of interest. Conclusions When population characteristics are reflected in large network components that dominate the population, RDS and ISS may produce samples that have statistically non-different prevalence values, even though some isolated network components may be under-sampled and/or statistically significantly different from the main groups. This so-called “strudel effect” is discussed in the paper. PMID:24360650

Climate Change Effects on Stream and River Biological Indicators: A Preliminary Analysis (External Review Draft)

EPA Science Inventory

This draft report is a preliminary assessment that describes how biological indicators are likely to respond to climate change, how well current sampling schemes may detect climate-driven changes, and how likely it is that these sampling schemes will continue to detect impairment...

Innovative Recruitment Using Online Networks: Lessons Learned From an Online Study of Alcohol and Other Drug Use Utilizing a Web-Based, Respondent-Driven Sampling (webRDS) Strategy

PubMed Central

Bauermeister, José A.; Zimmerman, Marc A.; Johns, Michelle M.; Glowacki, Pietreck; Stoddard, Sarah; Volz, Erik

2012-01-01

Objective: We used a web version of Respondent-Driven Sampling (webRDS) to recruit a sample of young adults (ages 18–24) and examined whether this strategy would result in alcohol and other drug (AOD) prevalence estimates comparable to national estimates (National Survey on Drug Use and Health [NSDUH]). Method: We recruited 22 initial participants (seeds) via Facebook to complete a web survey examining AOD risk correlates. Sequential, incentivized recruitment continued until our desired sample size was achieved. After correcting for webRDS clustering effects, we contrasted our AOD prevalence estimates (past 30 days) to NSDUH estimates by comparing the 95% confidence intervals of prevalence estimates. Results: We found comparable AOD prevalence estimates between our sample and NSDUH for the past 30 days for alcohol, marijuana, cocaine, Ecstasy (3,4-methylenedioxymethamphetamine, or MDMA), and hallucinogens. Cigarette use was lower than NSDUH estimates. Conclusions: WebRDS may be a suitable strategy to recruit young adults online. We discuss the unique strengths and challenges that may be encountered by public health researchers using webRDS methods. PMID:22846248

Comparing respondent-driven sampling and targeted sampling methods of recruiting injection drug users in San Francisco.

PubMed

Kral, Alex H; Malekinejad, Mohsen; Vaudrey, Jason; Martinez, Alexis N; Lorvick, Jennifer; McFarland, Willi; Raymond, H Fisher

2010-09-01

The objective of this article is to compare demographic characteristics, risk behaviors, and service utilization among injection drug users (IDUs) recruited from two separate studies in San Francisco in 2005, one which used targeted sampling (TS) and the other which used respondent-driven sampling (RDS). IDUs were recruited using TS (n = 651) and RDS (n = 534) and participated in quantitative interviews that included demographic characteristics, risk behaviors, and service utilization. Prevalence estimates and 95% confidence intervals (CIs) were calculated to assess whether there were differences in these variables by sampling method. There was overlap in 95% CIs for all demographic variables except African American race (TS: 45%, 53%; RDS: 29%, 44%). Maps showed that the proportion of IDUs distributed across zip codes were similar for the TS and RDS sample, with the exception of a single zip code that was more represented in the TS sample. This zip code includes an isolated, predominantly African American neighborhood where only the TS study had a field site. Risk behavior estimates were similar for both TS and RDS samples, although self-reported hepatitis C infection was lower in the RDS sample. In terms of service utilization, more IDUs in the RDS sample reported no recent use of drug treatment and syringe exchange program services. Our study suggests that perhaps a hybrid sampling plan is best suited for recruiting IDUs in San Francisco, whereby the more intensive ethnographic and secondary analysis components of TS would aid in the planning of seed placement and field locations for RDS.

Towards the estimation of effect measures in studies using respondent-driven sampling.

PubMed

Rotondi, Michael A

2014-06-01

Respondent-driven sampling (RDS) is an increasingly common sampling technique to recruit hidden populations. Statistical methods for RDS are not straightforward due to the correlation between individual outcomes and subject weighting; thus, analyses are typically limited to estimation of population proportions. This manuscript applies the method of variance estimates recovery (MOVER) to construct confidence intervals for effect measures such as risk difference (difference of proportions) or relative risk in studies using RDS. To illustrate the approach, MOVER is used to construct confidence intervals for differences in the prevalence of demographic characteristics between an RDS study and convenience study of injection drug users. MOVER is then applied to obtain a confidence interval for the relative risk between education levels and HIV seropositivity and current infection with syphilis, respectively. This approach provides a simple method to construct confidence intervals for effect measures in RDS studies. Since it only relies on a proportion and appropriate confidence limits, it can also be applied to previously published manuscripts.

HIV prevalence among people who inject drugs in Greater Kuala Lumpur recruited using respondent-driven sampling

PubMed Central

Bazazi, Alexander R.; Crawford, Forrest; Zelenev, Alexei; Heimer, Robert; Kamarulzaman, Adeeba; Altice, Frederick L.

2016-01-01

The HIV epidemic in Malaysia is concentrated among people who inject drugs (PWID). Accurate estimates of HIV prevalence are critical for developing appropriate treatment and prevention interventions for PWID in Malaysia. In 2010, 461 PWID were recruited using respondent-driven sampling in Greater Kuala Lumpur, Malaysia. Participants completed rapid HIV testing and behavioral assessments. Estimates of HIV prevalence were computed for each of the three recruitment sites and the overall sample. HIV prevalence was 15.8% (95% CI: 12.5-19.2%) overall but varied widely by location: 37.0% (28.6-45.4%) in Kampung Baru, 10.3% (5.0-15.6%) in Kajang, and 6.3% (3.0-9.5%) in Shah Alam. Recruitment extended to locations far from initial interview sites but was concentrated around discrete geographic regions. We document the high prevalence of HIV among PWID in Greater Kuala Lumpur. Sustained support for community surveillance and HIV prevention interventions is needed to stem the HIV epidemic among PWID in Malaysia. PMID:26358544

Social networks of men who have sex with men: a study of recruitment chains using Respondent Driven Sampling in Salvador, Bahia State, Brazil.

PubMed

Brignol, Sandra Mara Silva; Dourado, Inês; Amorim, Leila Denise; Miranda, José Garcia Vivas; Kerr, Lígia R F S

2015-11-01

Social and sexual contact networks between men who have sex with men (MSM) play an important role in understanding the transmission of HIV and other sexually transmitted infections (STIs). In Salvador (Bahia State, Brazil), one of the cities in the survey Behavior, Attitudes, Practices, and Prevalence of HIV and Syphilis among Men Who Have Sex with Men in 10 Brazilian Cities, data were collected in 2008/2009 from a sample of 383 MSM using Respondent Driven Sampling (RDS). Network analysis was used to study friendship networks and sexual partner networks. The study also focused on the association between the number of links (degree) and the number of sexual partners, in addition to socio-demographic characteristics. The networks' structure potentially facilitates HIV transmission. However, the same networks can also be used to spread messages on STI/HIV prevention, since the proximity and similarity of MSM in these networks can encourage behavior change and positive attitudes towards prevention.

Using the Precaution Adoption Process Model to Describe a Disaster Preparedness Intervention among Low-Income Latinos

ERIC Educational Resources Information Center

Glik, Deborah C.; Eisenman, David P.; Zhou, Qiong; Tseng, Chi-Hong; Asch, Steven M.

2014-01-01

Only 40-50% of households in the United States are currently disaster prepared. In this intervention study, respondent-driven sampling was used to select a sample (n = 187) of low income, Latino residents of Los Angeles County, randomly assigned into two treatment conditions: (i) household preparedness education received through…

Multiple strategies to identify HIV-positive black men who have sex with men and transgender women in New York City: a cross-sectional analysis of recruitment results.

PubMed

Franks, Julie; Mannheimer, Sharon B; Hirsch-Moverman, Yael; Hayes-Larson, Eleanor; Colson, Paul W; Ortega, Hugo; El-Sadr, Wafaa M

2018-03-01

Black men who have sex with men and transgender women are at high risk for HIV infection, but are more likely to be unaware of their infection or not in care for diagnosed HIV compared to other races. Respondent driven sampling has been advanced as a method to reach stigmatized and hidden populations for HIV testing. We compared strategies to recruit black, substance-using men who have sex with men and transgender women to identify newly diagnosed HIV infection, or those previously diagnosed but not in care. The STAR (Seek, Test, and Retain) study (ClinicalTrials.gov NCT01790360) used several recruitment strategies to identify black, substance-using men who have sex with men and transgender women with undiagnosed HIV infection or with previously diagnosed HIV infection but who were not in HIV care. Respondent-driven sampling, community-based recruitment and online advertising were used to recruit participants. Incentivized peer referral was integrated into all recruitment strategies. Participants completed interviewer-administered questionnaires and HIV testing. Demographic and HIV risk-related characteristics and recruitment strategy were summarized and stratified by HIV status. Associations were tested using Pearson's chi-squared, Fisher's exact, and Wilcoxon rank sum tests. Factors associated with HIV-positive diagnosis at p < 0.1 were included in a multivariable logistic regression model. From July 2012 through October 2015, the study enrolled 1929 participants; 96.3% men who have sex with men and 3.7% transgender women. Behavioural risk factors included recent condomless anal sex (55.6%) and recent substance use during sex (73.1%). HIV prevalence was 8.7%. In multivariable analysis, significant associations with HIV infection included being transgender; non-Hispanic black; gay/homosexual orientation; not homeless; and less likely to have insufficient income for necessities. Among recruitment strategies, respondent driven sampling was least effective in identifying HIV-positive participants. Integrating multiple recruitment strategies yielded a large sample of black men who have sex with men and transgender women at substantial risk for HIV. Respondent-driven sampling was less effective than other strategies at identifying men who have sex with men and transgender women with HIV. © 2018 The Authors. Journal of the International AIDS Society published by John Wiley & sons Ltd on behalf of the International AIDS Society.

One-step estimation of networked population size: Respondent-driven capture-recapture with anonymity.

PubMed

Khan, Bilal; Lee, Hsuan-Wei; Fellows, Ian; Dombrowski, Kirk

2018-01-01

Size estimation is particularly important for populations whose members experience disproportionate health issues or pose elevated health risks to the ambient social structures in which they are embedded. Efforts to derive size estimates are often frustrated when the population is hidden or hard-to-reach in ways that preclude conventional survey strategies, as is the case when social stigma is associated with group membership or when group members are involved in illegal activities. This paper extends prior research on the problem of network population size estimation, building on established survey/sampling methodologies commonly used with hard-to-reach groups. Three novel one-step, network-based population size estimators are presented, for use in the context of uniform random sampling, respondent-driven sampling, and when networks exhibit significant clustering effects. We give provably sufficient conditions for the consistency of these estimators in large configuration networks. Simulation experiments across a wide range of synthetic network topologies validate the performance of the estimators, which also perform well on a real-world location-based social networking data set with significant clustering. Finally, the proposed schemes are extended to allow them to be used in settings where participant anonymity is required. Systematic experiments show favorable tradeoffs between anonymity guarantees and estimator performance. Taken together, we demonstrate that reasonable population size estimates are derived from anonymous respondent driven samples of 250-750 individuals, within ambient populations of 5,000-40,000. The method thus represents a novel and cost-effective means for health planners and those agencies concerned with health and disease surveillance to estimate the size of hidden populations. We discuss limitations and future work in the concluding section.

Online respondent-driven sampling for studying contact patterns relevant for the spread of close-contact pathogens: a pilot study in Thailand.

PubMed

Stein, Mart L; van Steenbergen, Jim E; Chanyasanha, Charnchudhi; Tipayamongkholgul, Mathuros; Buskens, Vincent; van der Heijden, Peter G M; Sabaiwan, Wasamon; Bengtsson, Linus; Lu, Xin; Thorson, Anna E; Kretzschmar, Mirjam E E

2014-01-01

Information on social interactions is needed to understand the spread of airborne infections through a population. Previous studies mostly collected egocentric information of independent respondents with self-reported information about contacts. Respondent-driven sampling (RDS) is a sampling technique allowing respondents to recruit contacts from their social network. We explored the feasibility of webRDS for studying contact patterns relevant for the spread of respiratory pathogens. We developed a webRDS system for facilitating and tracking recruitment by Facebook and email. One-day diary surveys were conducted by applying webRDS among a convenience sample of Thai students. Students were asked to record numbers of contacts at different settings and self-reported influenza-like-illness symptoms, and to recruit four contacts whom they had met in the previous week. Contacts were asked to do the same to create a network tree of socially connected individuals. Correlations between linked individuals were analysed to investigate assortativity within networks. We reached up to 6 waves of contacts of initial respondents, using only non-material incentives. Forty-four (23.0%) of the initially approached students recruited one or more contacts. In total 257 persons participated, of which 168 (65.4%) were recruited by others. Facebook was the most popular recruitment option (45.1%). Strong assortative mixing was seen by age, gender and education, indicating a tendency of respondents to connect to contacts with similar characteristics. Random mixing was seen by reported number of daily contacts. Despite methodological challenges (e.g. clustering among respondents and their contacts), applying RDS provides new insights in mixing patterns relevant for close-contact infections in real-world networks. Such information increases our knowledge of the transmission of respiratory infections within populations and can be used to improve existing modelling approaches. It is worthwhile to further develop and explore webRDS for the detection of clusters of respiratory symptoms in social networks.

Online Respondent-Driven Sampling for Studying Contact Patterns Relevant for the Spread of Close-Contact Pathogens: A Pilot Study in Thailand

PubMed Central

Stein, Mart L.; van Steenbergen, Jim E.; Chanyasanha, Charnchudhi; Tipayamongkholgul, Mathuros; Buskens, Vincent; van der Heijden, Peter G. M.; Sabaiwan, Wasamon; Bengtsson, Linus; Lu, Xin; Thorson, Anna E.; Kretzschmar, Mirjam E. E.

2014-01-01

Background Information on social interactions is needed to understand the spread of airborne infections through a population. Previous studies mostly collected egocentric information of independent respondents with self-reported information about contacts. Respondent-driven sampling (RDS) is a sampling technique allowing respondents to recruit contacts from their social network. We explored the feasibility of webRDS for studying contact patterns relevant for the spread of respiratory pathogens. Materials and Methods We developed a webRDS system for facilitating and tracking recruitment by Facebook and email. One-day diary surveys were conducted by applying webRDS among a convenience sample of Thai students. Students were asked to record numbers of contacts at different settings and self-reported influenza-like-illness symptoms, and to recruit four contacts whom they had met in the previous week. Contacts were asked to do the same to create a network tree of socially connected individuals. Correlations between linked individuals were analysed to investigate assortativity within networks. Results We reached up to 6 waves of contacts of initial respondents, using only non-material incentives. Forty-four (23.0%) of the initially approached students recruited one or more contacts. In total 257 persons participated, of which 168 (65.4%) were recruited by others. Facebook was the most popular recruitment option (45.1%). Strong assortative mixing was seen by age, gender and education, indicating a tendency of respondents to connect to contacts with similar characteristics. Random mixing was seen by reported number of daily contacts. Conclusions Despite methodological challenges (e.g. clustering among respondents and their contacts), applying RDS provides new insights in mixing patterns relevant for close-contact infections in real-world networks. Such information increases our knowledge of the transmission of respiratory infections within populations and can be used to improve existing modelling approaches. It is worthwhile to further develop and explore webRDS for the detection of clusters of respiratory symptoms in social networks. PMID:24416371

How much of the cocaine market are we missing? Insights from respondent-driven sampling in a mid-sized American city.

PubMed

Caulkins, Jonathan P; Sussell, Jesse; Kilmer, Beau; Kasunic, Anna

2015-02-01

Studying markets for illegal drugs is important, but difficult. Data usually come from a selected subset of consumers, such as arrestees, treatment clients, or household survey respondents. There are rarely opportunities to study how such groups may differ from other market participants or how much of total consumption they represent. This paper uses respondent-driven sampling (RDS) of drug users in a mid-sized American city to estimate the shares of cocaine (powder and crack) users and expenditures that are attributable to different combinations of these groups. We find that those arrested in the last year accounted for 34% of past-month cocaine users and 40% of past-week cocaine spending in the RDS sample. Augmenting past-year arrestees with those who received treatment in the past year increases these values to 44% (users) and 55% (spending). Our results suggest that estimates based only on people who were arrested and/or treated in the past year would have to be inflated by 100-200% to capture the market totals. Adding those who own or rent their place of residence increased coverage in this study to 76% (users) and 81% (spending), suggesting that in theory the inflation factor could be reduced to 23-32% by supplementing data on arrestees and treatment populations with household data, although in practice rates of under-reporting by survey respondents may make coverage (sampling frame) a secondary concern for household surveys. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Potential and Challenges in Collecting Social and Behavioral Data on Adolescent Alcohol Norms: Comparing Respondent-Driven Sampling and Web-Based Respondent-Driven Sampling

PubMed Central

Hildebrand, Janina; Burns, Sharyn; Zhao, Yun; Lobo, Roanna; Howat, Peter; Allsop, Steve

2015-01-01

Background Respondent-driven sampling (RDS) is a method successfully used to research hard-to-access populations. Few studies have explored the use of the Internet and social media with RDS, known as Web-based RDS (WebRDS). This study explored the use of combining both “traditional” RDS and WebRDS to examine the influences on adolescent alcohol use. Objective This paper reports on the recruitment processes and the challenges and enablers of both RDS and WebRDS. It details comparative recruitment data and provides a summary of the utility of both methods for recruiting adolescents to participate in an online survey investigating youth alcohol norms. Methods Process evaluation data collected from research staff throughout the study were used to assess the challenges and solutions of RDS and WebRDS. Pearson chi-square test (Fisher’s exact test if applicable) was used to compare the differences in sociodemographics and drinking behavior between data collected by RDS and WebRDS. Results Of the total sample (N=1012), 232 adolescents were recruited by RDS and 780 by WebRDS. A significantly larger proportion of Aboriginal or Torres Strait Islander (P<.001) participants who spoke English as their main language at home (P=.03), and of middle and lower socioeconomic status (P<.001) was found in the RDS sample. The RDS sample was also found to have a higher occurrence of past 7-day drinking (P<.001) and past 7-day risky drinking (P=.004). No significant differences in gender, age, past month alcohol use, and lifetime alcohol use were observed between the RDS and WebRDS samples. This study revealed RDS and WebRDS used similar lengths of chains for recruiting participants; however, WebRDS conducted a faster rate of recruitment at a lower average cost per participant compared to RDS. Conclusions Using WebRDS resulted in significant improvements in the recruitment rate and was a more effective and efficient use of resources than the traditional RDS method. However, WebRDS resulted in partially different sample characteristics to traditional RDS. This potential effect should be considered when selecting the most appropriate data collection method. PMID:26704736

A comparison of respondent-driven and venue-based sampling of female sex workers in Liuzhou, China

PubMed Central

Weir, Sharon S; Merli, M Giovanna; Li, Jing; Gandhi, Anisha D; Neely, William W; Edwards, Jessie K; Suchindran, Chirayath M; Henderson, Gail E; Chen, Xiang-Sheng

2012-01-01

Objectives To compare two methods for sampling female sex workers (FSWs) for bio-behavioural surveillance. We compared the populations of sex workers recruited by the venue-based Priorities for Local AIDS Control Efforts (PLACE) method and a concurrently implemented network-based sampling method, respondent-driven sampling (RDS), in Liuzhou, China. Methods For the PLACE protocol, all female workers at a stratified random sample of venues identified as places where people meet new sexual partners were interviewed and tested for syphilis. Female workers who reported sex work in the past 4 weeks were categorised as FSWs. RDS used peer recruitment and chain referral to obtain a sample of FSWs. Data were collected between October 2009 and January 2010. We compared the socio-demographic characteristics and the percentage with a positive syphilis test of FSWs recruited by PLACE and RDS. Results The prevalence of a positive syphilis test was 24% among FSWs recruited by PLACE and 8.5% among those recruited by RDS and tested (prevalence ratio 3.3; 95% CI 1.5 to 7.2). Socio-demographic characteristics (age, residence and monthly income) also varied by sampling method. PLACE recruited fewer FSWs than RDS (161 vs 583), was more labour-intensive and had difficulty gaining access to some venues. RDS was more likely to recruit from areas near the RDS office and from large low prevalence entertainment venues. Conclusions Surveillance protocols using different sampling methods can obtain different estimates of prevalence and population characteristics. Venue-based and network-based methods each have strengths and limitations reflecting differences in design and assumptions. We recommend that more research be conducted on measuring bias in bio-behavioural surveillance. PMID:23172350

Respondent driven sampling in a biomonitoring study of refugees from Burma in Buffalo, New York who eat Great Lakes fish.

PubMed

Liu, Ming; McCann, Molly; Lewis-Michl, Elizabeth; Hwang, Syni-An

2018-06-01

Refugees from Burma who consume fish caught from local waterbodies have increased risk of exposure to environmental contaminants. We used respondent driven sampling (RDS) to sample this hard-to-reach population for the first Biomonitoring of Great Lakes Populations program. In the current study, we examined the interview data and assessed the effectiveness of RDS to sample the unique population. In 2013, we used RDS to sample 205 Burmese refugees and immigrants residing in Buffalo, New York who consumed fish caught from Great Lakes waters. RDS-adjusted population estimates of sociodemographic characteristics, residential history, fish consumption related behaviors, and awareness of fish advisories were obtained. We also examined sample homophily and equilibrium to assess how well the RDS assumptions were met in the study. Our sample was diverse with respect to sex, age, years residing in Buffalo, years lived in a refugee camp, education, employment, and fish consumption behaviors, and each of these variables reached equilibrium by the end of recruitment. Burmese refugees in Buffalo consumed Great Lakes fish throughout the year; a majority of them consumed the fish more than two times per week during summer, and about one third ate local fish more than once per week in winter. An estimated 60% of Burmese refugees in Buffalo had heard about local fish advisories. RDS has the potential to be an effective methodology for sampling refugees and immigrants in conducting biomonitoring and environmental exposure assessment. Due to high fish consumption and limited awareness and knowledge of fish advisories, some refugee and immigrant populations are more susceptible to environmental contaminants. Increased awareness on local fish advisories is needed among these populations. Published by Elsevier GmbH.

HIV Status Disclosure Among Infected Men Who Have Sex With Men (MSM) in Buenos Aires, Argentina

PubMed Central

Carballo-Diéguez, Alex; Balán, Iván C.; Dolezal, Curtis; Ibitoye, Mobolaji; Pando, María A.; Marone, Rubén; Barreda, Victoria; Ávila, María Mercedes

2013-01-01

Five hundred men who have sex with men were recruited in Buenos Aires using respondent driven sampling. Of them, 46 respondents (24 of them not gay identified) who were HIV infected were asked questions on serodisclosure. The sample was characterized by indicators of low socioeconomic status. Most of the respondents reported being in good to excellent health despite 42% of them having been diagnosed with AIDS. Only 10% of respondents had not disclosed their serostatus to at least one person. Coworkers and lovers or main sexual partners were those most likely to know the respondents' serostatus. Reactions to disclosure were for the most part supportive. Those who had not disclosed anticipated less favorable reactions than those who had disclosed. No significant differences were observed between gay and non-gay identified respondents. The progressive social environment of Argentina that includes federal laws recognizing gay marriage may contribute to create a climate favorable for serostatus disclosure. PMID:24245593

Our Health Counts Toronto: using respondent-driven sampling to unmask census undercounts of an urban indigenous population in Toronto, Canada.

PubMed

Rotondi, Michael A; O'Campo, Patricia; O'Brien, Kristen; Firestone, Michelle; Wolfe, Sara H; Bourgeois, Cheryllee; Smylie, Janet K

2017-12-26

To provide evidence of the magnitude of census undercounts of 'hard-to-reach' subpopulations and to improve estimation of the size of the urban indigenous population in Toronto, Canada, using respondent-driven sampling (RDS). Respondent-driven sampling. The study took place in the urban indigenous community in Toronto, Canada. Three locations within the city were used to recruit study participants. 908 adult participants (15+) who self-identified as indigenous (First Nation, Inuit or Métis) and lived in the city of Toronto. Study participants were generally young with over 60% of indigenous adults under the age of 45 years. Household income was low with approximately two-thirds of the sample living in households which earned less than $C20 000 last year. We collected baseline data on demographic characteristics, including indigenous identity, age, gender, income, household type and household size. Our primary outcome asked: 'Did you complete the 2011 Census Canada questionnaire?' Using RDS and our large-scale survey of the urban indigenous population in Toronto, Canada, we have shown that the most recent Canadian census underestimated the size of the indigenous population in Toronto by a factor of 2 to 4. Specifically, under conservative assumptions, there are approximately 55 000 (95% CI 45 000 to 73 000) indigenous people living in Toronto, at least double the current estimate of 19 270. Our indigenous enumeration methods, including RDS and census completion information will have broad impacts across governmental and health policy, potentially improving healthcare access for this community. These novel applications of RDS may be relevant for the enumeration of other 'hard-to-reach' populations, such as illegal immigrants or homeless individuals in Canada and beyond. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Viral hepatitis in female sex workers using the Respondent-Driven Sampling

PubMed Central

de Matos, Marcos André; França, Divânia Dias da Silva; Carneiro, Megmar Aparecida dos Santos; Martins, Regina Maria Bringel; Kerr, Lígia Regina Franco Sansigolo; Caetano, Karlla Antonieta Amorim; Pinheiro, Raquel Silva; de Araújo, Lyriane Apolinário; Mota, Rosa Maria Salani; de Matos, Marcia Alves Dias; Motta-Castro, Ana Rita Coimbra; Teles, Sheila Araújo

2017-01-01

ABSTRACT OBJECTIVE To estimate the prevalence of hepatitis B virus and C virus infections and their genotypes and analyze the risk factors for the markers of exposure to hepatitis B virus in female sex workers in a region of intense sex trade. METHODS This is a cross-sectional study performed with four hundred and two female sex workers in Goiânia, Brazil. Data have been collected using the Respondent-Driven Sampling. The women have been interviewed and tested for markers of hepatitis B and C viruses. Positive samples have been genotyped. The data have been analyzed using the Respondent-Driven Sampling Analysis Tool, version 5.3, and Stata 11.0. RESULTS The adjusted prevalence for hepatitis B virus and C virus were 17.1% (95%CI 11.6–23.4) and 0.7% (95%CI 0.1–1.5), respectively. Only 28% (95%CI 21.1–36.4) of the participants had serological evidence of vaccination against hepatitis B virus. Being older (> 40 years), being single, having a history of blood transfusion and use of cocaine, and ignoring the symptoms of sexually transmitted infections were associated with positivity for hepatitis B virus (p < 0.05). We have detected the subgenotype A1 of hepatitis B virus (n = 3) and the subtypes of hepatitis C virus 1a (n = 3) and 1b (n = 1). CONCLUSIONS We can observe a low prevalence of infection of hepatitis B and C viruses in the studied population. However, the findings of the analysis of the risk factors show the need for more investment in prevention programs for sexual and drug-related behavior, as well as more efforts to vaccinate this population against hepatitis B. The genotypes of the hepatitis B virus and C virus identified are consistent with those circulating in Brazil. PMID:28678904

Respondent-driven sampling and the recruitment of people with small injecting networks.

PubMed

Paquette, Dana; Bryant, Joanne; de Wit, John

2012-05-01

Respondent-driven sampling (RDS) is a form of chain-referral sampling, similar to snowball sampling, which was developed to reach hidden populations such as people who inject drugs (PWID). RDS is said to reach members of a hidden population that may not be accessible through other sampling methods. However, less attention has been paid as to whether there are segments of the population that are more likely to be missed by RDS. This study examined the ability of RDS to capture people with small injecting networks. A study of PWID, using RDS, was conducted in 2009 in Sydney, Australia. The size of participants' injecting networks was examined by recruitment chain and wave. Participants' injecting network characteristics were compared to those of participants from a separate pharmacy-based study. A logistic regression analysis was conducted to examine the characteristics independently associated with having small injecting networks, using the combined RDS and pharmacy-based samples. In comparison with the pharmacy-recruited participants, RDS participants were almost 80% less likely to have small injecting networks, after adjusting for other variables. RDS participants were also more likely to have their injecting networks form a larger proportion of those in their social networks, and to have acquaintances as part of their injecting networks. Compared to those with larger injecting networks, individuals with small injecting networks were equally likely to engage in receptive sharing of injecting equipment, but less likely to have had contact with prevention services. These findings suggest that those with small injecting networks are an important group to recruit, and that RDS is less likely to capture these individuals.

Respondent-Driven Sampling in a Multi-Site Study of Black and Latino Men Who Have Sex with Men.

PubMed

Murrill, Christopher S; Bingham, Trista; Lauby, Jennifer; Liu, Kai-Lih; Wheeler, Darrell; Carballo-Diéguez, Alex; Marks, Gary; Millett, Gregorio A

2016-02-01

Respondent-driven sampling (RDS) was used to recruit four samples of Black and Latino men who have sex with men (MSM) in three metropolitan areas to measure HIV prevalence and sexual and drug use behaviors. We compared demographic and behavioral risk characteristics of participants across sites, assessed the extent to which the RDS statistical adjustment procedure provides estimates that differ from the crude results, and summarized our experiences using RDS. From June 2005 to March 2006 a total of 2,235 MSM were recruited and interviewed: 614 Black MSM and 516 Latino MSM in New York City, 540 Black MSM in Philadelphia, and 565 Latino MSM in Los Angeles County. Crude point estimates for demographic characteristics, behavioral risk factors and HIV prevalence were calculated for each of the four samples. RDS Analysis Tool was used to obtain population-based estimates of each sampled population's characteristics. RDS adjusted estimates were similar to the crude estimates for each study sample on demographic characteristics such as age, income, education and employment status. Adjusted estimates of the prevalence of risk behaviors were lower than the crude estimates, and for three of the study samples, the adjusted HIV prevalence estimates were lower than the crude estimates. However, even the adjusted HIV prevalence estimates were higher than what has been previously estimated for these groups of MSM in these cities. Each site faced unique circumstances in implementing RDS. Our experience in using RDS among Black and Latino MSM resulted in diverse recruitment patterns and uncertainties in the estimated HIV prevalence and risk behaviors by study site. Copyright © 2016. Published by Elsevier Inc.

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

PubMed Central

2010-01-01

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 gathering respondents who are more representative of users in the general population than nonrandom methods of recruitment ordinarily produce. Conclusions Research on marijuana use, and other forms of drug use hidden in the general population of adults, is important for informing and extending harm reduction beyond its current emphasis on 'at-risk' populations. Expanding harm reduction in a normalizing context, through innovative research on users often overlooked, further challenges assumptions about reducing harm through prohibition of drug use and urges consideration of alternative policies such as decriminalization and legal regulation. PMID:20618944

Overlooked Threats to Respondent Driven Sampling Estimators: Peer Recruitment Reality, Degree Measures, and Random Selection Assumption.

PubMed

Li, Jianghong; Valente, Thomas W; Shin, Hee-Sung; Weeks, Margaret; Zelenev, Alexei; Moothi, Gayatri; Mosher, Heather; Heimer, Robert; Robles, Eduardo; Palmer, Greg; Obidoa, Chinekwu

2017-06-28

Intensive sociometric network data were collected from a typical respondent driven sample (RDS) of 528 people who inject drugs residing in Hartford, Connecticut in 2012-2013. This rich dataset enabled us to analyze a large number of unobserved network nodes and ties for the purpose of assessing common assumptions underlying RDS estimators. Results show that several assumptions central to RDS estimators, such as random selection, enrollment probability proportional to degree, and recruitment occurring over recruiter's network ties, were violated. These problems stem from an overly simplistic conceptualization of peer recruitment processes and dynamics. We found nearly half of participants were recruited via coupon redistribution on the street. Non-uniform patterns occurred in multiple recruitment stages related to both recruiter behavior (choosing and reaching alters, passing coupons, etc.) and recruit behavior (accepting/rejecting coupons, failing to enter study, passing coupons to others). Some factors associated with these patterns were also associated with HIV risk.

The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormone Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

DTIC Science & Technology

2014-09-30

axis and physiological processes driven by the GCs are essential for an individual’s ability to respond and adapt to stress, prolonged elevation of...health assessments. Stress and reproductive hormones (cortisol, aldosterone , thyroid, testosterone, progesterone) have been routinely measured in blood...in South Carolina. Laboratory Analyses Hormone concentrations (cortisol, aldosterone , reproductive and thyroid hormones) in serum samples have

HIV, HSV2 and Syphilis Prevalence in Female Sex Workers in Kerman, South-East Iran; Using Respondent-Driven Sampling

PubMed Central

Navadeh, S; Mirzazadeh, A; Mousavi, L; Haghdoost, AA; Fahimfar, N; Sedaghat, A

2012-01-01

Background We estimated the prevalence of HIV, sexually transmitted infections (STIs), and risky behaviors among female sex workers (FSW) in Kerman City, Iran. Methods: Women, 18 years or older, who reported selling sex for at least 6 months during their lifetime and had at least one sexual contact with a client in the recent 12 months were sampled using Responding Driven Sampling (RDS). Participants were interviewed about their sexual behaviors and provided whole blood for HIV, syphilis, and Herpes simplex type 2 (HSV2) testing. Data were analyzed using RDSAT Version 6.0 software. Results: Among samples of 177 FSW, we did not find any HIV positive cases. The weighted prevalence of syphilis and HSV2 were 7.2% and 18.0%, respectively. The reported STI syndromes for the proceeding year of the survey were 36%. Unprotected sexual contact was about 17–22% and link to injecting drug users through injection was about 18%. Conclusion: While this survey found no HIV, there were findings of risky sexual behaviors and STI, markers for potential infection for HIV. The prevalence of STI and sexual risk behaviors for HIV is considerably high in this subpopulation that alarming for an urgent public health preventive measures and national control-plan to be developed and implemented. PMID:23641392

Factors associated with HIV infection among a respondent-driven sample of men who have sex with men in Salvador, Brazil.

PubMed

Brignol, Sandra; Kerr, Ligia; Amorim, Leila Denise; Dourado, Inês

2016-01-01

Human immunodeficiency virus (HIV) continues to disproportionately affect men who have sex with men (MSM); therefore, we investigated the sociodemographic, biological, and sexual behavioral risk factors associated with HIV infection in the city of Salvador, Bahia. This study is part of the national survey Behavior, Attitudes, Practices and Prevalence of HIV and Syphilis among men who have sex with men in 10 Brazilian Cities, which is a cross-sectional survey whose participants were selected by means of the respondent-driven sampling. Exact logistic regression analysis was used to measure the association of potential risk factors with HIV infection due to an HIV prevalence lower than 10% and a small sample size (383). The prevalence of HIV was 6.3% (95%CI 3.9-8.8) and the risk factors associated with HIV infection in our adjusted final model included having never been tested for syphilis (OR = 3.1; 95%CI 1.3 - 7.3) and having more than eight sexual partners (OR = 3.3; 95%CI 1.4 - 8.1). This study highlights the high prevalence of HIV among MSM in the sample compared with the general population and confirms the importance of testing for syphilis in the context of the HIV epidemic as early detection may provide opportunities to prevent sexually transmitted diseases.

Challenges to Recruiting Population Representative Samples of Female Sex Workers in China Using Respondent Driven Sampling1

PubMed Central

Merli, M. Giovanna; Moody, James; Smith, Jeffrey; Li, Jing; Weir, Sharon; Chen, Xiangsheng

2014-01-01

We explore the network coverage of a sample of female sex workers (FSWs) in China recruited through Respondent Drive Sampling (RDS) as part of an effort to evaluate the claim of RDS of population representation with empirical data. We take advantage of unique information on the social networks of FSWs obtained from two overlapping studies --RDS and a venue-based sampling approach (PLACE) -- and use an exponential random graph modeling (ERGM) framework from local networks to construct a likely network from which our observed RDS sample is drawn. We then run recruitment chains over this simulated network to assess the assumption that the RDS chain referral process samples participants in proportion to their degree and the extent to which RDS satisfactorily covers certain parts of the network. We find evidence that, contrary to assumptions, RDS oversamples low degree nodes and geographically central areas of the network. Unlike previous evaluations of RDS which have explored the performance of RDS sampling chains on a non-hidden population, or the performance of simulated chains over previously mapped realistic social networks, our study provides a robust, empirically grounded evaluation of the performance of RDS chains on a real-world hidden population. PMID:24834869

Ketamine use among regular tobacco and alcohol users as revealed by respondent driven sampling in Taipei: prevalence, expectancy, and users’ risky decision making

PubMed Central

Chen, Wei J.; Ting, Te-Tien; Chang, Chao-Ming; Liu, Ying-Chun; Chen, Chuan-Yu

2014-01-01

The popularity of ketamine for recreational use among young people began to increase, particularly in Asia, in 2000. To gain more knowledge about the use of ketamine among high risk individuals, a respondent-driven sampling (RDS) was implemented among regular alcohol and tobacco users in the Taipei metropolitan area from 2007 to 2010. The sampling was initiated in three different settings (i.e., two in the community and one in a clinic) to recruit seed individuals. Each participant was asked to refer one to five friends known to be regular tobacco smokers and alcohol drinkers to participate in the present study. Incentives were offered differentially upon the completion of an interview and successful referral. Information pertaining to drug use experience was collected by an audio computer-assisted self-interview instrument. Software built for RDS analyses was used for data analyses. Of the 1,115 subjects recruited, about 11.7% of the RDS respondents reported ever having used ketamine. Positive expectancy of ketamine use was positively associated with ketamine use; in contrast, negative expectancy inversely associated with ketamine use. Decision-making characteristics as measured on the Iowa Gambling Task using reinforcement learning models revealed that ketamine users learned less from the most recent event than both tobacco- and drug-naïve controls and regular tobacco and alcohol users. These findings about ketamine use among young people have implications for its prevention and intervention. PMID:25264412

A Translational Approach to Validate in Vivo Anti-tumor Effects of Chloroquine on Breast Cancer Risk

DTIC Science & Technology

2014-05-01

performed at one month post- activation to ensure appropriate accruals with the sampling method, Respondent Driven Sampling (RDS), was encouraging...Add another country/ year of service *Repeat these questions as many times as the RPCV has tours of service. Are you currently active duty...chains.  Interim  analyses  were  performed  at  one  and  two  months  post-­‐ activation  to  ensure  appropriate

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

PubMed

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.

HIV prevalence among men who have sex with men in Brazil: results of the 2nd national survey using respondent-driven sampling.

PubMed

Kerr, Ligia; Kendall, Carl; Guimarães, Mark Drew Crosland; Salani Mota, Rosa; Veras, Maria Amélia; Dourado, Inês; Maria de Brito, Ana; Merchan-Hamann, Edgar; Pontes, Alexandre Kerr; Leal, Andréa Fachel; Knauth, Daniela; Castro, Ana Rita Coimbra Motta; Macena, Raimunda Hermelinda Maia; Lima, Luana Nepomuceno Costa; Oliveira, Lisangela Cristina; Cavalcantee, Maria do Socorro; Benzaken, Adele Schwartz; Pereira, Gerson; Pimenta, Cristina; Pascom, Ana Roberta Pati; Bermudez, Ximena Pamela Diaz; Moreira, Regina Célia; Brígido, Luis Fernando Macedo; Camillo, Ana Cláudia; McFarland, Willi; Johnston, Lisa G

2018-05-01

This paper reports human immuno-deficiency virus (HIV) prevalence in the 2nd National Biological and Behavioral Surveillance Survey (BBSS) among men who have sex with men (MSM) in 12 cities in Brazil using respondent-driven sampling (RDS).Following formative research, RDS was applied in 12 cities in the 5 macroregions of Brazil between June and December 2016 to recruit MSM for BBSS. The target sample size was 350 per city. Five to 6 seeds were initially selected to initiate recruitment and coupons and interviews were managed online. On-site rapid testing was used for HIV screening, and confirmed by a 2nd test. Participants were weighted using Gile estimator. Data from all 12 cities were merged and analyzed with Stata 14.0 complex survey data analysis tools in which each city was treated as its own strata. Missing data for those who did not test were imputed HIV+ if they reported testing positive before and were taking antiretroviral therapy.A total of 4176 men were recruited in the 12 cities. The average time to completion was 10.2 weeks. The longest chain length varied from 8 to 21 waves. The sample size was achieved in all but 2 cities.A total of 3958 of the 4176 respondents agreed to test for HIV (90.2%). For results without imputation, 17.5% (95%CI: 14.7-20.7) of our sample was HIV positive. With imputation, 18.4% (95%CI: 15.4-21.7) were seropositive.HIV prevalence increased beyond expectations from the results of the 2009 survey (12.1%; 95%CI: 10.0-14.5) to 18.4%; CI95%: 15.4 to 21.7 in 2016. This increase accompanies Brazil's focus on the treatment to prevention strategy, and a decrease in support for community-based organizations and community prevention programs.

HIV prevalence among men who have sex with men in Brazil: results of the 2nd national survey using respondent-driven sampling

PubMed Central

Kerr, Ligia; Kendall, Carl; Guimarães, Mark Drew Crosland; Salani Mota, Rosa; Veras, Maria Amélia; Dourado, Inês; Maria de Brito, Ana; Merchan-Hamann, Edgar; Pontes, Alexandre Kerr; Leal, Andréa Fachel; Knauth, Daniela; Castro, Ana Rita Coimbra Motta; Macena, Raimunda Hermelinda Maia; Lima, Luana Nepomuceno Costa; Oliveira, Lisangela Cristina; Cavalcantee, Maria do Socorro; Benzaken, Adele Schwartz; Pereira, Gerson; Pimenta, Cristina; Pascom, Ana Roberta Pati; Bermudez, Ximena Pamela Diaz; Moreira, Regina Célia; Brígido, Luis Fernando Macedo; Camillo, Ana Cláudia; McFarland, Willi; Johnston, Lisa G.

2018-01-01

Abstract This paper reports human immuno-deficiency virus (HIV) prevalence in the 2nd National Biological and Behavioral Surveillance Survey (BBSS) among men who have sex with men (MSM) in 12 cities in Brazil using respondent-driven sampling (RDS). Following formative research, RDS was applied in 12 cities in the 5 macroregions of Brazil between June and December 2016 to recruit MSM for BBSS. The target sample size was 350 per city. Five to 6 seeds were initially selected to initiate recruitment and coupons and interviews were managed online. On-site rapid testing was used for HIV screening, and confirmed by a 2nd test. Participants were weighted using Gile estimator. Data from all 12 cities were merged and analyzed with Stata 14.0 complex survey data analysis tools in which each city was treated as its own strata. Missing data for those who did not test were imputed HIV+ if they reported testing positive before and were taking antiretroviral therapy. A total of 4176 men were recruited in the 12 cities. The average time to completion was 10.2 weeks. The longest chain length varied from 8 to 21 waves. The sample size was achieved in all but 2 cities. A total of 3958 of the 4176 respondents agreed to test for HIV (90.2%). For results without imputation, 17.5% (95%CI: 14.7–20.7) of our sample was HIV positive. With imputation, 18.4% (95%CI: 15.4–21.7) were seropositive. HIV prevalence increased beyond expectations from the results of the 2009 survey (12.1%; 95%CI: 10.0–14.5) to 18.4%; CI95%: 15.4 to 21.7 in 2016. This increase accompanies Brazil's focus on the treatment to prevention strategy, and a decrease in support for community-based organizations and community prevention programs. PMID:29794604

Sex and Gender Diversity Among Transgender Persons in Ontario, Canada: Results From a Respondent-Driven Sampling Survey

PubMed Central

Scheim, Ayden I.; Bauer, Greta R.

2015-01-01

Recent estimates suggest that as many as 1 in 200 adults may be trans (transgender, transsexual, or transitioned). Knowledge about dimensions of sex and gender in trans populations is crucial to development of inclusive policy, practice, and research, but limited data have been available, particularly from probability samples. The Trans PULSE community-based research project surveyed trans Ontarians (n = 433) in 2009–2010 using respondent-driven sampling. Frequencies were weighted by recruitment probability to produce estimates for the networked Ontario trans population. An estimated 30% of trans Ontarians were living their day-to-day lives in their birth gender, and 23% were living in their felt gender with no medical intervention. In all, 42% were using hormones, while 15% of male-to-female spectrum persons had undergone vaginoplasty and 0.4% of female-to-male spectrum persons had had phalloplasty. Of those living in their felt gender, 59% had begun to do so within the past four years. A minority of trans Ontarians reported a linear transition from one sex to another, yet such a trajectory is often assumed to be the norm. Accounting for this observed diversity, we recommend policy and practice changes to increase social inclusion and service access for trans persons, regardless of transition status. PMID:24750105

Sex and gender diversity among transgender persons in Ontario, Canada: results from a respondent-driven sampling survey.

PubMed

Scheim, Ayden I; Bauer, Greta R

2015-01-01

Recent estimates suggest that as many as 1 in 200 adults may be trans (transgender, transsexual, or transitioned). Knowledge about dimensions of sex and gender in trans populations is crucial to development of inclusive policy, practice, and research, but limited data have been available, particularly from probability samples. The Trans PULSE community-based research project surveyed trans Ontarians (n=433) in 2009-2010 using respondent-driven sampling. Frequencies were weighted by recruitment probability to produce estimates for the networked Ontario trans population. An estimated 30% of trans Ontarians were living their day-to-day lives in their birth gender, and 23% were living in their felt gender with no medical intervention. In all, 42% were using hormones, while 15% of male-to-female spectrum persons had undergone vaginoplasty and 0.4% of female-to-male spectrum persons had had phalloplasty. Of those living in their felt gender, 59% had begun to do so within the past four years. A minority of trans Ontarians reported a linear transition from one sex to another, yet such a trajectory is often assumed to be the norm. Accounting for this observed diversity, we recommend policy and practice changes to increase social inclusion and service access for trans persons, regardless of transition status.

Using Online Respondent Driven Sampling for Vietnamese Youths' Alcohol Use and Associated Risk Factors

PubMed Central

Zhang, Melvyn W. B.; Tran, Bach Xuan; Le, Huong Thi; Long, Nguyen Hoang; Le, Huong Thi; Hinh, Nguyen Duc; Tho, Tran Dinh; Le, Bao Nguyen; Thuc, Vu Thi Minh; Ngo, Chau; Tu, Nguyen Huu; Latkin, Carl A.; Ho, Roger CM

2017-01-01

Objectives The average alcohol consumption per capita among Vietnamese adults has consistently increased. Although alcohol-related disorders have been extensively studied, there is a paucity of research shedding light on this issue among Internet users. The study aimed to examine the severity of alcohol-related disorders and other associated factors that might predispose individuals towards alcohol usage in a sample of youths recruited online. Methods An online cross-sectional study was conducted with 1,080 Vietnamese youths. A standardized questionnaire was used. Respondent-driven sampling was applied to recruit participants. Multivariate logistic and Tobit regressions were utilized to identify the associated factors. Results About 59.5% of the males and 12.7% of the total youths declared that they were actively using alcohol. From the total sample, a cumulative total of 32.3% of the participants were drinking alcohol, with 21.8% and 25.0% of the participants being classified as drinking hazardously and binge drinkers, respectively. The majority of the participants (60.7%) were in the pre-contemplative stage. Conclusions A high prevalence of hazardous drinking was recognized among online Vietnamese youths. In addition, we found relationships between alcohol use disorder and other addictive disorders, such as tobacco smoking and water-pipe usage. Our results highlighted that the majority of the individuals are not receptive to the idea of changing their alcohol habits, and this would imply that there ought to be more government effort towards the implementation of effective alcohol control policies. PMID:28523209

Use of respondent driven sampling (RDS) generates a very diverse sample of men who have sex with men (MSM) in Buenos Aires, Argentina.

PubMed

Carballo-Diéguez, Alex; Balan, Ivan; Marone, Rubén; Pando, María A; Dolezal, Curtis; Barreda, Victoria; Leu, Cheng-Shiun; Avila, María Mercedes

2011-01-01

Prior research focusing on men who have sex with men (MSM) conducted in Buenos Aires, Argentina, used convenience samples that included mainly gay identified men. To increase MSM sample representativeness, we used Respondent Driven Sampling (RDS) for the first time in Argentina. Using RDS, under certain specified conditions, the observed estimates for the percentage of the population with a specific trait are asymptotically unbiased. We describe, the diversity of the recruited sample, from the point of view of sexual orientation, and contrast the different subgroups in terms of their HIV sexual risk behavior. 500 MSM were recruited using RDS. Behavioral data were collected through face-to-face interviews and Web-based CASI. In contrast with prior studies, RDS generated a very diverse sample of MSM from a sexual identity perspective. Only 24.5% of participants identified as gay; 36.2% identified as bisexual, 21.9% as heterosexual, and 17.4% were grouped as "other." Gay and non-gay identified MSM differed significantly in their sexual behavior, the former having higher numbers of partners, more frequent sexual contacts and less frequency of condom use. One third of the men (gay, 3%; bisexual, 34%, heterosexual, 51%; other, 49%) reported having had sex with men, women and transvestites in the two months prior to the interview. This population requires further study and, potentially, HIV prevention strategies tailored to such diversity of partnerships. Our results highlight the potential effectiveness of using RDS to reach non-gay identified MSM. They also present lessons learned in the implementation of RDS to recruit MSM concerning both the importance and limitations of formative work, the need to tailor incentives to circumstances of the less affluent potential participants, the need to prevent masking, and the challenge of assessing network size.

Use of Respondent Driven Sampling (RDS) Generates a Very Diverse Sample of Men Who Have Sex with Men (MSM) in Buenos Aires, Argentina

PubMed Central

Carballo-Diéguez, Alex; Balan, Ivan; Marone, Rubén; Pando, María A.; Dolezal, Curtis; Barreda, Victoria; Leu, Cheng-Shiun; Ávila, María Mercedes

2011-01-01

Background Prior research focusing on men who have sex with men (MSM) conducted in Buenos Aires, Argentina, used convenience samples that included mainly gay identified men. To increase MSM sample representativeness, we used Respondent Driven Sampling (RDS) for the first time in Argentina. Using RDS, under certain specified conditions, the observed estimates for the percentage of the population with a specific trait are asymptotically unbiased. We describe, the diversity of the recruited sample, from the point of view of sexual orientation, and contrast the different subgroups in terms of their HIV sexual risk behavior. Methodology 500 MSM were recruited using RDS. Behavioral data were collected through face-to-face interviews and Web-based CASI. Conclusion In contrast with prior studies, RDS generated a very diverse sample of MSM from a sexual identity perspective. Only 24.5% of participants identified as gay; 36.2% identified as bisexual, 21.9% as heterosexual, and 17.4% were grouped as “other.” Gay and non-gay identified MSM differed significantly in their sexual behavior, the former having higher numbers of partners, more frequent sexual contacts and less frequency of condom use. One third of the men (gay, 3%; bisexual, 34%, heterosexual, 51%; other, 49%) reported having had sex with men, women and transvestites in the two months prior to the interview. This population requires further study and, potentially, HIV prevention strategies tailored to such diversity of partnerships. Our results highlight the potential effectiveness of using RDS to reach non-gay identified MSM. They also present lessons learned in the implementation of RDS to recruit MSM concerning both the importance and limitations of formative work, the need to tailor incentives to circumstances of the less affluent potential participants, the need to prevent masking, and the challenge of assessing network size. PMID:22102896

Reproducibility of Respondent-Driven Sampling (RDS) in Repeat Surveys of Men Who have Sex with Men, Unguja, Zanzibar.

PubMed

Khatib, Ahmed; Haji, Shaaban; Khamis, Maryam; Said, Christen; Khalid, Farhat; Dahoma, Mohammed; Ali, Ameir; Othman, Asha; Welty, Susie; McFarland, Willi

2017-07-01

To assess the reproducibility of respondent-driven sampling (RDS) in obtaining comparable samples across two survey rounds, we conducted integrated bio-behavioral surveillance surveys (IBBSS) using RDS in 2007 and 2011 among men who have sex with men (MSM) on Unguja island in Zanzibar. Differences in the two rounds were assessed by comparing RDS-adjusted population estimates, stratified estimates, and bottleneck plots. Participants in the 2011 survey round were younger (31.4 vs. 9.9% under 19 years old, p < 0.001), more likely to have tested for HIV in the last year (53.7 vs. 10.6%, p < 0.001), and less likely to have injected drugs in the last 3 months (1.0 vs. 23.2%, p < 0.001) compared to participants in the 2007 round. HIV prevalence was 12.3% in 2007 compared to 2.6% in 2011 (p < 0.001). The difference in HIV prevalence persisted after stratifying and adjusting for known differences in the two surveys rounds. Bottleneck plots suggest that recruitment chains were "trapped" in the social networks of MSM who injected drugs to a greater extent in 2007 than in 2011. We conclude that the two rounds of RDS sampled different subsets of the MSM population on Unguja, particularly with respect to inclusion of MSM within the social networks of people who inject drugs. Findings underscore the need to evaluate the reproducibility of RDS in repeated rounds of IBBSS and to develop new sampling methods for key populations at high risk for HIV in order to track the epidemic, develop evidence-based prevention and care programs, and assess their impact.

Hepatitis C virus infection among drug injectors in St Petersburg, Russia: social and molecular epidemiology of an endemic infection.

PubMed

Paintsil, Elijah; Verevochkin, Sergei V; Dukhovlinova, Elena; Niccolai, Linda; Barbour, Russell; White, Edward; Toussova, Olga V; Alexander, Louis; Kozlov, Andrei P; Heimer, Robert

2009-11-01

To understand the epidemiology and transmission patterns of hepatitis C virus (HCV), the predominant blood borne-pathogen infecting injection drug users (IDUs), in a part of the former Soviet Union. Cross-sectional respondent-driven sample of IDUs. St Petersburg, Russia. A total of 387 IDUs were recruited in late 2005 and throughout 2006. Participants were surveyed to collect demographic, medical and both general and dyad-specific drug injection and sexual behaviors. A blood sample was collected to detect antibodies to hepatitis C and to amplify viral RNA for molecular analysis. The molecular data, including genotypes, were analyzed spatially and linkage patterns were compared to the social linkages obtained by respondent-driven sampling (RDS) for chains of respondents and among the injection dyads. HCV infection was all but ubiquitous: 94.6% of IDUs were HCV-seropositive. Among the 209 viral sequences amplified, genotype 3a predominated (n = 119, 56.9%), followed by 1b (n = 61, 29.2%) and 1a (n = 25, 11.9%). There was no significant clustering of genotypes spatially. Neither genotypes nor closely related sequences were clustered within RDS chains. Analysis of HCV sequences from dyads failed to find associations of genotype or sequence homology within pairs. Genotyping reveals that there have been at least five unique introductions of HCV genotypes into the IDU community in St Petersburg. Analysis of prevalent infections does not appear to correlate with the social networks of IDUs, suggesting that simple approaches to link these networks to prevalent infections, rather than incident transmission, will not prove meaningful. On a more positive note, the majority of IDUs are infected with 3a genotype that is associated with sustained virological response to antiviral therapy.

Selecting Communication Channels for Substance Misuse Prevention with At-Risk African-American Emerging Adults Living in the Southern United States

ERIC Educational Resources Information Center

Tucker, Jalie A.; Cheong, JeeWon; Chandler, Susan D.

2016-01-01

Natural health information sources used by African-American emerging adults were investigated to identify sources associated with high and low substance-related risk. Participants (110 males, 234 females; M age = 18.9 years) were recruited using respondent-driven sampling, and structured interviews assessed substance use, sources of health…

Community mapping and respondent-driven sampling of gay and bisexual men’s communities in Vancouver, Canada

PubMed Central

Forrest, Jamie I; Stevenson, Benjamin; Rich, Ashleigh; Michelow, Warren; Pai, Jayaram; Jollimore, Jody; Raymond, H. Fisher; Moore, David; Hogg, Robert S; Roth, Eric A

2014-01-01

Literature suggests formative research is vital for those using respondent-driven sampling (RDS) to study hidden populations of interest. However, few authors have described in detail how different qualitative methodologies can address the objectives of formative research for understanding the social network properties of the study population, selecting seeds, and adapting survey logistics to best fit the population. In this paper we describe the use of community mapping exercises as a tool within focus groups to collect data on social and sexual network characteristics of gay and bisexual men in the metropolitan area of Vancouver, Canada. Three key themes emerged from analyzing community maps along with other formative research data: (a) connections between physical spaces and social networks of gay and bisexual men, (b) diversity in communities, and (c) substance use connected with formation of sub-communities. We discuss how these themes informed the planning and operations of a longitudinal epidemiological cohort study recruited by RDS. We argue that using community mapping within formative research is a valuable qualitative tool for characterizing network structures of a diverse and differentiated population of gay and bisexual men in a highly developed urban setting. PMID:24512070

The prevalence of human immunodeficiency virus and sexually transmitted infections among female sex workers in Shiraz, South of Iran: by respondent-driven sampling.

PubMed

Kazerooni, Parvin Afsar; Motazedian, Nasrin; Motamedifar, Mohammad; Sayadi, Mehrab; Sabet, Mojghan; Lari, Mahmood Amini; Kamali, Kianoush

2014-02-01

As a concentrated epidemic, human immunodeficiency virus (HIV) is spreading rapidly in one or more groups in Iran, but in the general population its prevalence is relatively low. Female sex workers (FSWs) and their partners are at greater risk for HIV infection. To determine the prevalence of HIV and sexually transmitted infections (STIs) including gonorrhoea, Chlamydia, herpes simplex type 2 and syphilis among FSWs. We conducted a cross-sectional study of 278 FSWs in Shiraz, by using respondent-driven sampling, from June to March 2010. The recruitment chain started with 14 seeds, and FSWs were tested for HIV, syphilis, herpes simplex type 2, gonorrhoea and Chlamydia. HIV prevalence was 4.7% (13/278); the most prevalent STI was herpes simplex type 2, 9.7% (27/278), followed by Chlamydia 9% (25/278), gonorrhoea 1.4% (4/278) and syphilis (0/278). The FSWs reported drug use (69.9%) of which 16.4% had history of injecting drug use. Unprotected sex in the past month was reported by 24.4% of FSWs. Urgent education and risk reduction programmes are needed in this population.

Evaluating outcome-correlated recruitment and geographic recruitment bias in a respondent-driven sample of people who inject drugs in Tijuana, Mexico.

PubMed

Rudolph, Abby E; Gaines, Tommi L; Lozada, Remedios; Vera, Alicia; Brouwer, Kimberly C

2014-12-01

Respondent-driven sampling's (RDS) widespread use and reliance on untested assumptions suggests a need for new exploratory/diagnostic tests. We assessed geographic recruitment bias and outcome-correlated recruitment among 1,048 RDS-recruited people who inject drugs (Tijuana, Mexico). Surveys gathered demographics, drug/sex behaviors, activity locations, and recruiter-recruit pairs. Simulations assessed geographic and network clustering of active syphilis (RPR titers ≥1:8). Gender-specific predicted probabilities were estimated using logistic regression with GEE and robust standard errors. Active syphilis prevalence was 7 % (crude: men = 5.7 % and women = 16.6 %; RDS-adjusted: men = 6.7 % and women = 7.6 %). Syphilis clustered in the Zona Norte, a neighborhood known for drug and sex markets. Network simulations revealed geographic recruitment bias and non-random recruitment by syphilis status. Gender-specific prevalence estimates accounting for clustering were highest among those living/working/injecting/buying drugs in the Zona Norte and directly/indirectly connected to syphilis cases (men: 15.9 %, women: 25.6 %) and lowest among those with neither exposure (men: 3.0 %, women: 6.1 %). Future RDS analyses should assess/account for network and spatial dependencies.

Does size really matter? A sensitivity analysis of number of seeds in a respondent-driven sampling study of gay, bisexual and other men who have sex with men in Vancouver, Canada.

PubMed

Lachowsky, Nathan John; Sorge, Justin Tyler; Raymond, Henry Fisher; Cui, Zishan; Sereda, Paul; Rich, Ashleigh; Roth, Eric A; Hogg, Robert S; Moore, David M

2016-11-16

Respondent-driven sampling (RDS) is an increasingly used peer chain-recruitment method to sample "hard-to-reach" populations for whom there are no reliable sampling frames. Implementation success of RDS varies; one potential negative factor being the number of seeds used. We conducted a sensitivity analysis on estimates produced using data from an RDS study of gay, bisexual and other men who have sex with men (GBMSM) aged ≥16 years living in Vancouver, Canada. Participants completed a questionnaire on demographics, sexual behavior and substance use. For analysis, we used increasing seed exclusion criteria, starting with all participants and subsequently removing unproductive seeds, chains of ≤1 recruitment waves, and chains of ≤2 recruitment waves. We calculated estimates for three different outcomes (HIV serostatus, condomless anal intercourse with HIV discordant/unknown status partner, and injecting drugs) using three different RDS weighting procedures: RDS-I, RDS-II, and RDS-SS. We also assessed seed dependence with bottleneck analyses and convergence plots. Statistical differences between RDS estimators were assessed through simulation analysis. Overall, 719 participants were recruited, which included 119 seeds and a maximum of 16 recruitment waves (mean chain length = 1.7). The sample of >0 recruitment waves removed unproductive seeds (n = 50/119, 42.0%), resulting in 69 chains (mean length = 3.0). The sample of >1 recruitment waves removed 125 seeds or recruits (17.4% of overall sample), resulting in 37 chains (mean length = 4.8). The final sample of >2 recruitment waves removed a further 182 seeds or recruits (25.3% of overall sample), resulting in 25 chains (mean length = 6.1). Convergence plots and bottleneck analyses of condomless anal intercourse with HIV discordant/unknown status partner and injecting drugs outcomes were satisfactory. For these two outcomes, regardless of seed exclusion criteria used, the crude proportions fell within 95% confidence intervals of all RDS-weighted estimates. Significant differences between the three RDS estimators were not observed. Within a sample of GBMSM in Vancouver, Canada, this RDS study suggests that when equilibrium and homophily are met, although potentially costly and time consuming, analysis is not negatively affected by large numbers of unproductive or lowly productive seeds.

An Immunization Strategy for Hidden Populations.

PubMed

Chen, Saran; Lu, Xin

2017-06-12

Hidden populations, such as injecting drug users (IDUs), sex workers (SWs) and men who have sex with men (MSM), are considered at high risk of contracting and transmitting infectious diseases such as AIDS, gonorrhea, syphilis etc. However, public health interventions to such groups are prohibited due to strong privacy concerns and lack of global information, which is a necessity for traditional strategies such as targeted immunization and acquaintance immunization. In this study, we introduce an innovative intervention strategy to be used in combination with a sampling approach that is widely used for hidden populations, Respondent-driven Sampling (RDS). The RDS strategy is implemented in two steps: First, RDS is used to estimate the average degree (personal network size) and degree distribution of the target population with sample data. Second, a cut-off threshold is calculated and used to screen the respondents to be immunized. Simulations on model networks and real-world networks reveal that the efficiency of the RDS strategy is close to that of the targeted strategy. As the new strategy can be implemented with the RDS sampling process, it provides a cost-efficient and feasible approach for disease intervention and control for hidden populations.

Sexting among young adults

PubMed Central

Gordon-Messer, Deborah; Bauermeister, Jose Arturo; Grodzinski, Alison; Zimmerman, Marc

2012-01-01

Purpose Sexting has stirred debate over its legality and safety, but few researchers have documented the relationship between sexting and health. We describe the sexting behavior of young adults in the United States, and examine its association with sexual behavior and psychological well-being. Methods Using an adapted web version of Respondent-Driven Sampling (webRDS) we recruited a sample of U.S. young adults (ages 18 to 24; N=3447). We examined participant sexting behavior using 4 categories of sexting: 1) Non-Sexters, 2) Receivers, 3) Senders, and 4) Two-way Sexters. We then assessed the relationships between sexting categories and sociodemographic characteristics, sexual behavior and psychological well-being. Results Over half (57%) of respondents were Non-Sexters, 28.2% of the sample were Two-way Sexters, 12.6% were Receivers, and 2% were Senders. Males were more likely to be Receivers than females. Sexually active respondents were more likely to be Two-way Sexters than non-sexually active respondents. Among participants who were sexually active in the past 30 days, we found no differences across sexting groups in number of sexual partners, or number of unprotected sex partners in the past 30 days. We also found no relationship between sexting and psychological well-being. Conclusions Our results suggest that sexting is not related to sexual risk behavior or psychological well-being. We discuss the findings of this study and propose directions for further research on sexting. PMID:23299018

Network Sampling with Memory: A proposal for more efficient sampling from social networks.

PubMed

Mouw, Ted; Verdery, Ashton M

2012-08-01

Techniques for sampling from networks have grown into an important area of research across several fields. For sociologists, the possibility of sampling from a network is appealing for two reasons: (1) A network sample can yield substantively interesting data about network structures and social interactions, and (2) it is useful in situations where study populations are difficult or impossible to survey with traditional sampling approaches because of the lack of a sampling frame. Despite its appeal, methodological concerns about the precision and accuracy of network-based sampling methods remain. In particular, recent research has shown that sampling from a network using a random walk based approach such as Respondent Driven Sampling (RDS) can result in high design effects (DE)-the ratio of the sampling variance to the sampling variance of simple random sampling (SRS). A high design effect means that more cases must be collected to achieve the same level of precision as SRS. In this paper we propose an alternative strategy, Network Sampling with Memory (NSM), which collects network data from respondents in order to reduce design effects and, correspondingly, the number of interviews needed to achieve a given level of statistical power. NSM combines a "List" mode, where all individuals on the revealed network list are sampled with the same cumulative probability, with a "Search" mode, which gives priority to bridge nodes connecting the current sample to unexplored parts of the network. We test the relative efficiency of NSM compared to RDS and SRS on 162 school and university networks from Add Health and Facebook that range in size from 110 to 16,278 nodes. The results show that the average design effect for NSM on these 162 networks is 1.16, which is very close to the efficiency of a simple random sample (DE=1), and 98.5% lower than the average DE we observed for RDS.

Network Sampling with Memory: A proposal for more efficient sampling from social networks

PubMed Central

Mouw, Ted; Verdery, Ashton M.

2013-01-01

Techniques for sampling from networks have grown into an important area of research across several fields. For sociologists, the possibility of sampling from a network is appealing for two reasons: (1) A network sample can yield substantively interesting data about network structures and social interactions, and (2) it is useful in situations where study populations are difficult or impossible to survey with traditional sampling approaches because of the lack of a sampling frame. Despite its appeal, methodological concerns about the precision and accuracy of network-based sampling methods remain. In particular, recent research has shown that sampling from a network using a random walk based approach such as Respondent Driven Sampling (RDS) can result in high design effects (DE)—the ratio of the sampling variance to the sampling variance of simple random sampling (SRS). A high design effect means that more cases must be collected to achieve the same level of precision as SRS. In this paper we propose an alternative strategy, Network Sampling with Memory (NSM), which collects network data from respondents in order to reduce design effects and, correspondingly, the number of interviews needed to achieve a given level of statistical power. NSM combines a “List” mode, where all individuals on the revealed network list are sampled with the same cumulative probability, with a “Search” mode, which gives priority to bridge nodes connecting the current sample to unexplored parts of the network. We test the relative efficiency of NSM compared to RDS and SRS on 162 school and university networks from Add Health and Facebook that range in size from 110 to 16,278 nodes. The results show that the average design effect for NSM on these 162 networks is 1.16, which is very close to the efficiency of a simple random sample (DE=1), and 98.5% lower than the average DE we observed for RDS. PMID:24159246

Review of sampling hard-to-reach and hidden populations for HIV surveillance.

PubMed

Magnani, Robert; Sabin, Keith; Saidel, Tobi; Heckathorn, Douglas

2005-05-01

Adequate surveillance of hard-to-reach and 'hidden' subpopulations is crucial to containing the HIV epidemic in low prevalence settings and in slowing the rate of transmission in high prevalence settings. For a variety of reasons, however, conventional facility and survey-based surveillance data collection strategies are ineffective for a number of key subpopulations, particularly those whose behaviors are illegal or illicit. This paper critically reviews alternative sampling strategies for undertaking behavioral or biological surveillance surveys of such groups. Non-probability sampling approaches such as facility-based sentinel surveillance and snowball sampling are the simplest to carry out, but are subject to a high risk of sampling/selection bias. Most of the probability sampling methods considered are limited in that they are adequate only under certain circumstances and for some groups. One relatively new method, respondent-driven sampling, an adaptation of chain-referral sampling, appears to be the most promising for general applications. However, as its applicability to HIV surveillance in resource-poor settings has yet to be established, further field trials are needed before a firm conclusion can be reached.

Prevalence of STI symptoms and high levels of stigma in STI healthcare among men who have sex with men in Dar es Salaam, Tanzania: a respondent-driven sampling study.

PubMed

Ross, Michael W; Larsson, Markus; Nyoni, Joyce E; Agardh, Anette

2017-08-01

Symptoms of sexually transmitted infections (STIs), whether they are presented for treatment or diagnosis, and how they are received by the clinician where they are presented, may be concomitants of stigma associated with homosexuality in homophobic climates. We analyzed respondent-driven sampling data from a study on 200 young men who have sex with men (MSM) in Dar es Salaam, Tanzania to examine sample prevalence, treatment and clinician response to 10 symptoms potentially associated with STIs. Survey measures included 10 self-reported STI symptoms, further specified according to location (genital, anal, oral), further specified according to place of diagnosis, place of, treatment whether there was pharmacy treatment or self-medication, healthcare worker (HCW) inquiries about source of infection and whether the HCW was polite. Most common symptoms reported were genital pain, burning urination, genital itching/burning, penile discharge, and groin swelling. Anal symptoms had the lowest proportion of treatment at public clinics and among the highest proportion of pharmacy treatment; anal sores had the highest proportion of self-medication. HCWs were reported as not being polite in response to 71-90% of the symptoms, (median = 82%). The findings suggest that stigma and negative HCW response are barriers to public clinic treatment for MSM in Tanzania and that these may have implications for both STI treatment and the HIV cascade.

Burden and characteristics of HIV infection among female sex workers in Kampala, Uganda - a respondent-driven sampling survey.

PubMed

Hladik, Wolfgang; Baughman, Andrew L; Serwadda, David; Tappero, Jordan W; Kwezi, Rachel; Nakato, Namakula D; Barker, Joseph

2017-06-10

Sex workers in Uganda are at significant risk for HIV infection. We characterized the HIV epidemic among Kampala female sex workers (FSW). We used respondent-driven sampling to sample FSW aged 15+ years who reported having sold sex to men in the preceding 30 days; collected data through audio-computer assisted self-interviews, and tested blood, vaginal and rectal swabs for HIV, syphilis, neisseria gonorrhea, chlamydia trachomatis, and trichomonas vaginalis. A total of 942 FSW were enrolled from June 2008 through April 2009. The overall estimated HIV prevalence was 33% (95% confidence intervals [CI] 30%-37%) and among FSW 25 years or older was 44%. HIV infection is associated with low levels of schooling, having no other work, never having tested for HIV, self-reported genital ulcers or sores, and testing positive for neisseria gonorrhea or any sexually transmitted infections (STI). Two thirds (65%) of commercial sex acts reportedly were protected by condoms; one in five (19%) FSW reported having had anal sex. Gender-based violence was frequent; 34% reported having been raped and 24% reported having been beaten by clients in the preceding 30 days. One in three FSW in Kampala is HIV-infected, suggesting a severe HIV epidemic in this population. Intensified interventions are warranted to increase condom use, HIV testing, STI screening, as well as antiretroviral treatment and pre-exposure prophylaxis along with measures to overcome gender-based violence.

Identification of Homophily and Preferential Recruitment in Respondent-Driven Sampling.

PubMed

Crawford, Forrest W; Aronow, Peter M; Zeng, Li; Li, Jianghong

2018-01-01

Respondent-driven sampling (RDS) is a link-tracing procedure used in epidemiologic research on hidden or hard-to-reach populations in which subjects recruit others via their social networks. Estimates from RDS studies may have poor statistical properties due to statistical dependence in sampled subjects' traits. Two distinct mechanisms account for dependence in an RDS study: homophily, the tendency for individuals to share social ties with others exhibiting similar characteristics, and preferential recruitment, in which recruiters do not recruit uniformly at random from their network alters. The different effects of network homophily and preferential recruitment in RDS studies have been a source of confusion and controversy in methodological and empirical research in epidemiology. In this work, we gave formal definitions of homophily and preferential recruitment and showed that neither is identified in typical RDS studies. We derived nonparametric identification regions for homophily and preferential recruitment and showed that these parameters were not identified unless the network took a degenerate form. The results indicated that claims of homophily or recruitment bias measured from empirical RDS studies may not be credible. We applied our identification results to a study involving both a network census and RDS on a population of injection drug users in Hartford, Connecticut (2012-2013). © 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.

Assessing differences in groups randomized by recruitment chain in a respondent-driven sample of Seattle-area injection drug users.

PubMed

Burt, Richard D; Thiede, Hanne

2014-11-01

Respondent-driven sampling (RDS) is a form of peer-based study recruitment and analysis that incorporates features designed to limit and adjust for biases in traditional snowball sampling. It is being widely used in studies of hidden populations. We report an empirical evaluation of RDS's consistency and variability, comparing groups recruited contemporaneously, by identical methods and using identical survey instruments. We randomized recruitment chains from the RDS-based 2012 National HIV Behavioral Surveillance survey of injection drug users in the Seattle area into two groups and compared them in terms of sociodemographic characteristics, drug-associated risk behaviors, sexual risk behaviors, human immunodeficiency virus (HIV) status and HIV testing frequency. The two groups differed in five of the 18 variables examined (P ≤ .001): race (e.g., 60% white vs. 47%), gender (52% male vs. 67%), area of residence (32% downtown Seattle vs. 44%), an HIV test in the previous 12 months (51% vs. 38%). The difference in serologic HIV status was particularly pronounced (4% positive vs. 18%). In four further randomizations, differences in one to five variables attained this level of significance, although the specific variables involved differed. We found some material differences between the randomized groups. Although the variability of the present study was less than has been reported in serial RDS surveys, these findings indicate caution in the interpretation of RDS results. Copyright © 2014 Elsevier Inc. All rights reserved.

Prevalence of Human Immunodeficiency Virus and Sexually Transmitted Infections Among Cisgender and Transgender Women Sex Workers in Greater Kuala Lumpur, Malaysia: Results From a Respondent-Driven Sampling Study.

PubMed

Wickersham, Jeffrey A; Gibson, Britton A; Bazazi, Alexander R; Pillai, Veena; Pedersen, Courtney J; Meyer, Jaimie P; El-Bassel, Nabila; Mayer, Kenneth H; Kamarulzaman, Adeeba; Altice, Frederick L

2017-11-01

Sex workers face a disproportionate burden of human immunodeficiency virus (HIV) and sexually transmitted infections (STI) worldwide. For cisgender women sex workers (CWSW), global HIV prevalence is over 10%, whereas transgender women sex workers (TWSW) face an HIV burden of 19% to 27%. We used respondent-driven sampling to recruit 492 sex workers, including CWSW (n = 299) and TWSW (n = 193) in Greater Kuala Lumpur, Malaysia. Participants completed an in-depth survey and were screened for HIV, syphilis, Chlamydia trachomatis, and Neisseria gonorrhoeae. Sample characteristics stratified by gender identity and interview site are presented. Bivariate analyses comparing CWSW and TWSW were conducted using independent samples t tests for continuous variables and χ tests for categorical variables. Pooled HIV prevalence was high (11.7%; 95% confidence interval [CI], 8.8-14.5), and was similar for CWSW (11.1%) and TWSW (12.4%). Rates of syphilis 25.5% (95% CI, 21.6-29.5), C. trachomatis (14.8%; 95% CI, 11.6-18.0) and N. gonorrhoeae (5.8%; 95% CI, 3.7-7.9) were also concerning. Both groups reported lifetime HIV testing (62.4%), but CWSW were less likely to have ever been HIV tested (54.5%) than TWSW (74.6%). Median time since last HIV test was 24 months. Previous screening for STI was low. Inconsistent condom use and drug use during sex work were not uncommon. High HIV and STI prevalence, coupled with infrequent HIV and STI screening, inconsistent condom use, and occupational drug use, underscore the need for expanded HIV and STI prevention, screening, and treatment efforts among CWSW and TWSW in Malaysia.

A qualitative analysis of peer recruitment pressures in respondent driven sampling: Are risks above the ethical limit?

PubMed

Mosher, Heather I; Moorthi, Gayatri; Li, JiangHong; Weeks, Margaret R

2015-09-01

This paper examines peer recruitment dynamics through respondent driven sampling (RDS) with a sample of injection drug users in Hartford, CT to understand the strategies participants use to recruit peers into a study and the extent to which these strategies may introduce risks above the ethical limit despite safeguards in RDS. Out of 526 injection drug users who participated in a mixed-method RDS methodology evaluation study, a nested sample of 61 participants completed an in-depth semi-structured interview at a 2-month follow-up to explore their experiences with the recruitment process. Findings revealed that participants used a variety of strategies to recruit peers, ranging from one-time interactions to more persistent strategies to encourage participation (e.g., selecting peers that can easily be found and contacted later, following up with peers to remind them of their appointment, accompanying peers to the study site, etc.). Some participants described the more persistent strategies as helpful, while some others experienced these strategies as minor peer pressure, creating a feeling of obligation to participate. Narratives revealed that overall, the probability of experiencing study-related risks remains relatively low for most participants; however, a disconcerting finding was that higher study-related risks (e.g., relationship conflict, loss of relationship, physical fights, violence) were seen for recruits who participated but switched coupons or for recruits who decided not to participate in the study and did not return the coupon to the recruiter. Findings indicate that peer recruitment practices in RDS generally pose minimal risk, but that peer recruitment may occasionally exceed the ethical limit, and that enhanced safeguards for studies using peer recruitment methods are recommended. Suggestions for possible enhancements are described. Copyright © 2015 Elsevier B.V. All rights reserved.

Respondent-driven sampling for an adolescent health study in vulnerable urban settings: a multi-country study.

PubMed

Decker, Michele R; Marshall, Beth Dail; Emerson, Mark; Kalamar, Amanda; Covarrubias, Laura; Astone, Nan; Wang, Ziliang; Gao, Ersheng; Mashimbye, Lawrence; Delany-Moretlwe, Sinead; Acharya, Rajib; Olumide, Adesola; Ojengbede, Oladosu; Blum, Robert W; Sonenstein, Freya L

2014-12-01

The global adolescent population is larger than ever before and is rapidly urbanizing. Global surveillance systems to monitor youth health typically use household- and school-based recruitment methods. These systems risk not reaching the most marginalized youth made vulnerable by conditions of migration, civil conflict, and other forms of individual and structural vulnerability. We describe the methodology of the Well-Being of Adolescents in Vulnerable Environments survey, which used respondent-driven sampling (RDS) to recruit male and female youth aged 15-19 years and living in economically distressed urban settings in Baltimore, MD; Johannesburg, South Africa; Ibadan, Nigeria; New Delhi, India; and Shanghai, China (migrant youth only) for a cross-sectional study. We describe a shared recruitment and survey administration protocol across the five sites, present recruitment parameters, and illustrate challenges and necessary adaptations for use of RDS with youth in disadvantaged urban settings. We describe the reach of RDS into populations of youth who may be missed by traditional household- and school-based sampling. Across all sites, an estimated 9.6% were unstably housed; among those enrolled in school, absenteeism was pervasive with 29% having missed over 6 days of school in the past month. Overall findings confirm the feasibility, efficiency, and utility of RDS in quickly reaching diverse samples of youth, including those both in and out of school and those unstably housed, and provide direction for optimizing RDS methods with this population. In our rapidly urbanizing global landscape with an unprecedented youth population, RDS may serve as a valuable tool in complementing existing household- and school-based methods for health-related surveillance that can guide policy. Copyright © 2014 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

Respondent-driven sampling for an adolescent health study in vulnerable urban settings: a multi-country study

PubMed Central

Decker, Michele R.; Marshall, Beth; Emerson, Mark; Kalamar, Amanda; Covarrubias, Laura; Astone, Nan; Wang, Ziliang; Gao, Ersheng; Mashimbye, Lawrence; Delany-Moretlwe, Sinead; Acharya, Rajib; Olumide, Adesola; Ojengbede, Oladosu; Blum, Robert

2015-01-01

The global adolescent population is larger than ever before and is rapidly urbanizing. Global surveillance systems to monitor youth health typically use household- and school-based recruitment methods. These systems risk not reaching the most marginalized youth made vulnerable by conditions of migration, civil conflict and other forms of individual and structural vulnerability. We describe the methodology of the Well Being of Adolescents in Vulnerable Environments (WAVE) survey, which used respondent-driven sampling (RDS) to recruit male and female youth aged 15 to 19 years and living in economically distressed urban settings in Baltimore, USA, Johannesburg, South Africa, Ibadan, Nigeria, Delhi, India and Shanghai, China (migrant youth only) for a cross-sectional study. We describe a shared recruitment and survey administration protocol across the five sites, present recruitment parameters, and illustrate challenges and necessary adaptations for use of RDS with youth in disadvantaged urban settings. We describe the reach of RDS into populations of youth who may be missed by traditional householdbased and school-based sampling. Across all sites, an estimated 9.6% were unstably housed; among those enrolled in school, absenteeism was pervasive with 29% having missed over 6 days of school in the past month. Overall findings confirm the feasibility, efficiency and utility of RDS in quickly reaching diverse samples of youth, including those both in and out of school and those unstably housed, and provide direction for optimizing RDS methods with this population. In our rapidly urbanizing global landscape with an unprecedented youth population, RDS may serve as a valuable tool in complementing existing household- and school-based methods for health-related surveillance that can guide policy. PMID:25454005

"They got their program, and I got mine": a cautionary tale concerning the ethical implications of using respondent-driven sampling to study injection drug users.

PubMed

Scott, Greg

2008-02-01

This article examines the ethical implications of using respondent-driven sampling (RDS) to conduct HIV behaviour surveillance among injection drug users (IDUs) in Chicago. Ethnographic inquiry illustrates how the design and implementation of RDS invites if not promotes manifold violations of federal guidelines governing human research subject protections. Post hoc structured interviews with approximately 13% (n=70) of the behaviour surveillance sample (N=529) focused on how RDS's "dual incentive" structure affected participants' social, economic, and cultural milieu. Triangulated methods include interviews with owners of 20 "shooting galleries", unofficial and illegal locales where IDUs congregate and 400 h of traditional ethnographic observation of individual IDUs and IDU networks. "Consensus analysis" allows identification of key cultural domains that define the RDS coupon market. The study reveals the power of RDS to foment a stratified market of research participation that reinforces pre-existing economic and social inequalities among IDUs. Participants co-opted RDS to develop various "underground" revenue-generating modalities that produced differential risks and benefits among participants. Deleterious outcomes include false advertising regarding the study's risks and benefits, exploitation of relative economic deprivation, generation of sero-discordant social networks, and interpersonal and organised conflict, coercion, and violence. Although RDS may involve serious ethical violations it remains the best available means for accruing a representative sample of hidden populations. It is critical, however, to supplement RDS with research into (1) the subjects' cultural, social, economic, and political contexts, (2) the potential human subjects violations that participants experience, and (3) how these two issues might affect data integrity and interpretation.

Evaluating the Inter-Respondent (Consumer vs. Staff) Reliability and Construct Validity (SIS vs. Vineland) of the Supports Intensity Scale on a Dutch Sample

ERIC Educational Resources Information Center

Claes, C.; Van Hove, G.; van Loon, J.; Vandevelde, S.; Schalock, R. L.

2009-01-01

Background: Despite various reliability studies on the Supports Intensity Scale (SIS), to date there has not been an evaluation of the reliability of client vs. staff judgments. Such determination is important, given the increasing consumer-driven approach to services. Additionally, there has not been an evaluation of the instrument's construct…

Evaluating respondent-driven sampling as an implementation tool for universal coverage of antiretroviral studies among men who have sex with men living with HIV.

PubMed

Baral, Stefan D; Ketende, Sosthenes; Schwartz, Sheree; Orazulike, Ifeanyi; Ugoh, Kelechi; Peel, Sheila A; Ake, Julie; Blattner, William; Charurat, Manhattan

2015-03-01

The TRUST model based on experimental and observational data posits that integration of HIV prevention and universal coverage of antiretroviral treatment at a trusted community venue provides a framework for achieving effective reduction in HIV-related morbidity and mortality among men who have sex with men (MSM) living with HIV, as well as reducing HIV incidence. The analyses presented here evaluate the utility of respondent-driven sampling as an implementation tool for engaging MSM in the TRUST intervention. The TRUST integrated prevention and treatment model was established at a trusted community center serving MSM in Abuja, Nigeria. Five seeds have resulted in 3-26 waves of accrual between March 2013 and August 2014, with results presented here characterizing HIV burden and engagement in HIV care for 722 men across study recruitment waves. For analytic purposes, the waves were collapsed into 5 groups: 4 equally spaced (0-4, 5-9, 10-14, and 15-19) and 1 ranging from the 20th to the 26th wave with significance assessed using Pearson χ2 test. In earlier waves, MSM were more likely to have reported testing for HIV (82.9% in waves 0-4, 47.7% in waves 20-26; P < 0.01). In addition, biologically confirmed HIV prevalence decreased from an average of 59.1% to 42.9% (P < 0.05) in later waves. In earlier waves, about 80% of participants correctly reported their HIV status as compared with less than 25% in the later waves (P < 0.01). Finally, participants reporting being on ART decreased from 50% to 22.2% in later waves (P < 0.01). Implementation science studies focused on demonstrating impact of universal HIV treatment programs among people living with HIV necessitate different accrual methods than those focused on preventing HIV acquisition. Here, respondent-driven sampling was shown to be an efficient method for reaching marginalized populations of MSM living with HIV in Nigeria, and engaging them in universal HIV treatment services.

Depression literacy among Australians of Chinese-speaking background in Melbourne, Australia.

PubMed

Wong, Fu Keung Daniel; Lam, Yuk Kit Angus; Poon, Ada

2010-01-19

This study investigated the knowledge of depression and preference for professional help, medications and treatment methods among Australians of Chinese-speaking background, and the perceptions of this population of the causes of mental illness. Adopting a cluster convenience sampling method, the study recruited 200 Chinese-speaking subjects from four major areas in metropolitan Melbourne where many Chinese live. The respondents were presented with a vignette describing an individual with depression and then asked questions to assess their understanding of depression and preference for professional help, medications and treatment methods. A comparative approach was used to compare the findings with those of a previous study of the mental health literacy of Australian and Japanese adults. Compared to the Australian and Japanese samples, a much lower percentage of Chinese-speaking Australians (14%) could correctly identify major depression described in the vignette, and a higher percentage believed that counseling professionals could be helpful. Higher percentages of those who believed that close family members could be helpful were found in the Chinese-speaking Australian and Japanese samples, and these two groups also expressed more uncertainty about the usefulness or harmfulness of certain medications compared to the Australian sample. Higher percentages of respondents in both the Chinese-speaking Australian and the Australian sample considered "lifestyle changes" to be helpful compared to the Japanese sample. In the Chinese-speaking sample, 30%, 17.4%, 33% and 27% of the respondents rated "traditional Chinese medicine doctors," "Chinese herbal medications," "taking Chinese nutritional foods/supplements" and "qiqong" as helpful. Many perceived "changing fungshui" and "traditional Chinese worship" to be harmful. Regarding the perception of causes of mental illness, items related to psychosocial perspectives including "life stress" and "interpersonal conflict" were rated highly by the respondents, whereas traditional beliefs including "punishment for misdeeds conducted by ancestors" and "demon possession" had the lowest ratings. Campaigns to increase the mental health literacy of Chinese-speaking Australians are needed. The above-mentioned socially and culturally driven beliefs need to be taken into consideration in the development of culturally relevant education programs.

Depression literacy among Australians of Chinese-speaking background in Melbourne, Australia

PubMed Central

2010-01-01

Background This study investigated the knowledge of depression and preference for professional help, medications and treatment methods among Australians of Chinese-speaking background, and the perceptions of this population of the causes of mental illness. Methods Adopting a cluster convenience sampling method, the study recruited 200 Chinese-speaking subjects from four major areas in metropolitan Melbourne where many Chinese live. The respondents were presented with a vignette describing an individual with depression and then asked questions to assess their understanding of depression and preference for professional help, medications and treatment methods. A comparative approach was used to compare the findings with those of a previous study of the mental health literacy of Australian and Japanese adults. Results Compared to the Australian and Japanese samples, a much lower percentage of Chinese-speaking Australians (14%) could correctly identify major depression described in the vignette, and a higher percentage believed that counseling professionals could be helpful. Higher percentages of those who believed that close family members could be helpful were found in the Chinese-speaking Australian and Japanese samples, and these two groups also expressed more uncertainty about the usefulness or harmfulness of certain medications compared to the Australian sample. Higher percentages of respondents in both the Chinese-speaking Australian and the Australian sample considered "lifestyle changes" to be helpful compared to the Japanese sample. In the Chinese-speaking sample, 30%, 17.4%, 33% and 27% of the respondents rated "traditional Chinese medicine doctors," "Chinese herbal medications," "taking Chinese nutritional foods/supplements" and "qiqong" as helpful. Many perceived "changing fungshui" and "traditional Chinese worship" to be harmful. Regarding the perception of causes of mental illness, items related to psychosocial perspectives including "life stress" and "interpersonal conflict" were rated highly by the respondents, whereas traditional beliefs including "punishment for misdeeds conducted by ancestors" and "demon possession" had the lowest ratings. Conclusions Campaigns to increase the mental health literacy of Chinese-speaking Australians are needed. The abovementioned socially and culturally driven beliefs need to be taken into consideration in the development of culturally relevant education programs. PMID:20082724

High Substance Use and HIV Risk Behavior Among Young Argentine Men Who Have Sex with Men.

PubMed

Balán, Iván C; Frasca, Timothy; Pando, María A; Marone, Rubén O; Barreda, Victoria; Dolezal, Curtis; Carballo-Diéguez, Alex; Ávila, María M

2018-04-01

In the United States young men who have sex with men have higher rates of substance use, higher HIV incidence, and less frequent HIV testing than their heterosexual counterparts and older MSM. Less is known about comparable populations in Latin America. As part of an epidemiological study, MSM were recruited through Respondent Driven Sampling in the metropolitan area of Buenos Aires, Argentina and answered a computerized behavioral survey. From the total of 500 MSM enrolled, a sub-sample of 233 aged 18-25 was analyzed. The sample was concentrated among lower socioeconomic strata, and only 16% identified as gay. Nearly half reported male, female, and transvestite sexual partners. Reported substance use was widespread ranging from 61% for marijuana to 20% for pasta base (cocaine sulfate). Seventy percent of the sample had never been tested for HIV infection; 3% tested positive for HIV and 8% for syphilis during the study.

Respondent-Driven Sampling of Injection Drug Users in Two U.S.–Mexico Border Cities: Recruitment Dynamics and Impact on Estimates of HIV and Syphilis Prevalence

PubMed Central

Brouwer, Kimberly C.; Firestone Cruz, Michelle A.; Ramos, Rebeca; Ramos, Maria Elena; Lozada, Remedios M.; Magis-Rodriguez, Carlos; Strathdee, Steffanie A.

2006-01-01

Respondent-driven sampling (RDS), a chain referral sampling approach, is increasingly used to recruit participants from hard-to-reach populations, such as injection drug users (IDUs). Using RDS, we recruited IDUs in Tijuana and Ciudad (Cd.) Juárez, two Mexican cities bordering San Diego, CA and El Paso, TX, respectively, and compared recruitment dynamics, reported network size, and estimates of HIV and syphilis prevalence. Between February and April 2005, we used RDS to recruit IDUs in Tijuana (15 seeds, 207 recruits) and Cd. Juárez (9 seeds, 197 recruits), Mexico for a cross-sectional study of behavioral and contextual factors associated with HIV, HCV and syphilis infections. All subjects provided informed consent, an anonymous interview, and a venous blood sample for serologic testing of HIV, HCV, HBV (Cd. Juárez only) and syphilis antibody. Log-linear models were used to analyze the association between the state of the recruiter and that of the recruitee in the referral chains, and population estimates of the presence of syphilis antibody were obtained, correcting for biased sampling using RDS-based estimators. Sampling of the targeted 200 recruits per city was achieved rapidly (2 months in Tijuana, 2 weeks in Cd. Juárez). After excluding seeds and missing data, the sample prevalence of HCV, HIV and syphilis were 96.6, 1.9 and 13.5% respectively in Tijuana, and 95.3, 4.1, and 2.7% respectively in Cd. Juárez (where HBV prevalence was 84.7%). Syphilis cases were clustered in recruitment trees. RDS-corrected estimates of syphilis antibody prevalence ranged from 12.8 to 26.8% in Tijuana and from 2.9 to 15.6% in Ciudad Juárez, depending on how recruitment patterns were modeled, and assumptions about how network size affected an individual’s probability of being included in the sample. RDS was an effective method to rapidly recruit IDUs in these cities. Although the frequency of HIV was low, syphilis prevalence was high, particularly in Tijuana. RDS-corrected estimates of syphilis prevalence were sensitive to model assumptions, suggesting that further validation of RDS is necessary. PMID:17072761

Share2Quit: Web-Based Peer-Driven Referrals for Smoking Cessation

PubMed Central

2013-01-01

Background Smoking is the number one preventable cause of death in the United States. Effective Web-assisted tobacco interventions are often underutilized and require new and innovative engagement approaches. Web-based peer-driven chain referrals successfully used outside health care have the potential for increasing the reach of Internet interventions. Objective The objective of our study was to describe the protocol for the development and testing of proactive Web-based chain-referral tools for increasing the access to Decide2Quit.org, a Web-assisted tobacco intervention system. Methods We will build and refine proactive chain-referral tools, including email and Facebook referrals. In addition, we will implement respondent-driven sampling (RDS), a controlled chain-referral sampling technique designed to remove inherent biases in chain referrals and obtain a representative sample. We will begin our chain referrals with an initial recruitment of former and current smokers as seeds (initial participants) who will be trained to refer current smokers from their social network using the developed tools. In turn, these newly referred smokers will also be provided the tools to refer other smokers from their social networks. We will model predictors of referral success using sample weights from the RDS to estimate the success of the system in the targeted population. Results This protocol describes the evaluation of proactive Web-based chain-referral tools, which can be used in tobacco interventions to increase the access to hard-to-reach populations, for promoting smoking cessation. Conclusions Share2Quit represents an innovative advancement by capitalizing on naturally occurring technology trends to recruit smokers to Web-assisted tobacco interventions. PMID:24067329

Social networks of men who have sex with men and their implications for HIV/STI interventions: results from a cross-sectional study using respondent-driven sampling in a large and a small city in Tanzania.

PubMed

Ross, Michael W; Larsson, Markus; Jacobson, Jerry; Nyoni, Joyce; Agardh, Anette

2016-11-18

Men who have sex with men (MSM) in sub-Saharan Africa remain hidden and hard to reach for involvement in HIV and sexually transmitted infection (STI) services. The aim of the current study was to describe MSM social networks in a large and a small Tanzanian city in order to explore their utility for peer-based healthcare interventions. Data were collected through respondent-driven sampling (RDS) in Dar es Salaam (n=197) and in Tanga (n=99) in 2012 and 2013, using 5 and 4 seeds, respectively. All results were adjusted for RDS sampling design. Mean personal network size based on the number of MSM who were reported by the participants, as known to them was 12.0±15.5 in Dar es Salaam and 7.6±8.1 in Tanga. Mean actual RDS network size was 39.4±31.4 in Dar es Salaam and 25.3±9.7 in Tanga. A majority (97%) reported that the person from whom they received the recruitment coupon was a sexual partner, close friend or acquaintance. Homophile in recruitment patterns (selective affiliation) was present for age, gay openness, and HIV status in Dar es Salaam, and for sexual identification in Tanga. The personal network sizes and existence of contacts between recruiter and referral indicate that it is possible to use peer-driven interventions to reach MSM for HIV/STI interventions in larger and smaller sub-Saharan African cities. The study was reviewed and approved by the University of Texas Health Science Center's Institutional Review Board (HSC-SPH-10-0033) and the Tanzanian National Institute for Medical Research (NIMR/HQ/R.8a/Vol. IX/1088). 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/.

The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormone Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

DTIC Science & Technology

2013-09-30

physiological processes driven by the GCs are essential for an individual’s ability to respond and adapt to stress, prolonged elevation of GC hormones...capture-release health assessments. Stress and reproductive hormones (cortisol, aldosterone , thyroid, testosterone, progesterone) have been routinely...ACE) Basin, also in South Carolina. Laboratory Analyses Hormone concentrations (cortisol, aldosterone , reproductive and thyroid hormones) in

Social network characteristics and HIV vulnerability among transgender persons in San Salvador: identifying opportunities for HIV prevention strategies.

PubMed

Barrington, Clare; Wejnert, Cyprian; Guardado, Maria Elena; Nieto, Ana Isabel; Bailey, Gabriela Paz

2012-01-01

The purpose of this study is to improve understanding of HIV vulnerability and opportunities for HIV prevention within the social networks of male-to-female transgender persons in San Salvador, El Salvador. We compare HIV prevalence and behavioral data from a sample of gay-identified men who have sex with men (MSM) (n = 279), heterosexual or bisexual identified MSM (n = 229) and transgender persons (n = 67) recruited using Respondent Driven Sampling. Transgender persons consistently reported higher rates of HIV risk behavior than the rest of the study population and were significantly more likely to be involved in sex work. While transgender persons reported the highest rates of exposure to HIV educational activities they had the lowest levels of HIV-related knowledge. Transgender respondents' social networks were homophilous and efficient at recruiting other transgender persons. Findings suggest that transgender social networks could provide an effective and culturally relevant opportunity for HIV prevention efforts in this vulnerable population.

The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormone Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

DTIC Science & Technology

2013-09-30

establishment of homeostasis. While the HPA axis and physiological processes driven by the GCs are essential for an individual’s ability to respond and...relying upon methods which include capture-release health assessments. Stress and reproductive hormones (cortisol, aldosterone , thyroid...in the Ashepoo, Combahee and Edisto (ACE) Basin, also in South Carolina. Laboratory Analyses Hormone concentrations (cortisol, aldosterone

The Bottlenose Dolphin (Tursiops truncatus) as a Model to Understand Variation in Stress and Reproductive Hormones Measures in Relation to Sampling Matrix, Demographics, and Environmental Factors

DTIC Science & Technology

2014-09-30

While the HPA axis and physiological processes driven by the GCs are essential for an individual’s ability to respond and adapt to stress, prolonged...relying upon methods which include capture-release health assessments. Stress and reproductive hormones (cortisol, aldosterone , thyroid, testosterone...the Ashepoo, Combahee and Edisto (ACE) Basin, also in South Carolina. Laboratory Analyses Hormone concentrations (cortisol, aldosterone

HIV risk practices by female sex workers according to workplace.

PubMed

Damacena, Giseli Nogueira; Szwarcwald, Célia Landmann; Souza Júnior, Paulo Roberto Borges de

2014-06-01

OBJECTIVE To investigate differences in HIV infection- related risk practices by Female Sex Workers according to workplace and the effects of homophily on estimating HIV prevalence. METHODS Data from 2,523 women, recruited using Respondent-Driven Sampling, were used for the study carried out in 10 Brazilian cities in 2008-2009. The study included female sex workers aged 18 and over. The questionnaire was completed by the subjects and included questions on characteristics of professional activity, sexual practices, use of drugs, HIV testing, and access to health services. HIV quick tests were conducted. The participants were classified in two groups according to place of work: on the street or indoor venues, like nightclubs and saunas. To compare variable distributions by place of work, we used Chi-square homogeneity tests, taking into consideration unequal selection probabilities as well as the structure of dependence between observations. We tested the effect of homophily by workplace on estimated HIV prevalence. RESULTS The highest HIV risk practices were associated with: working on the streets, lower socioeconomic status, low regular smear test coverage, higher levels of crack use and higher levels of syphilis serological scars as well as higher prevalence of HIV infection. The effect of homophily was higher among sex workers in indoor venues. However, it did not affect the estimated prevalence of HIV, even after using a post-stratification by workplace procedure. CONCLUSIONS The findings suggest that strategies should focus on extending access to, and utilization of, health services. Prevention policies should be specifically aimed at street workers. Regarding the application of Respondent-Driven Sampling, the sample should be sufficient to estimate transition probabilities, as the network develops more quickly among sex workers in indoor venues.

HIV risk practices by female sex workers according to workplace

PubMed Central

Damacena, Giseli Nogueira; Szwarcwald, Célia Landmann; de Souza, Paulo Roberto Borges

2014-01-01

OBJECTIVE To investigate differences in HIV infection- related risk practices by Female Sex Workers according to workplace and the effects of homophily on estimating HIV prevalence. METHODS Data from 2,523 women, recruited using Respondent-Driven Sampling, were used for the study carried out in 10 Brazilian cities in 2008-2009. The study included female sex workers aged 18 and over. The questionnaire was completed by the subjects and included questions on characteristics of professional activity, sexual practices, use of drugs, HIV testing, and access to health services. HIV quick tests were conducted. The participants were classified in two groups according to place of work: on the street or indoor venues, like nightclubs and saunas. To compare variable distributions by place of work, we used Chi-square homogeneity tests, taking into consideration unequal selection probabilities as well as the structure of dependence between observations. We tested the effect of homophily by workplace on estimated HIV prevalence. RESULTS The highest HIV risk practices were associated with: working on the streets, lower socioeconomic status, low regular smear test coverage, higher levels of crack use and higher levels of syphilis serological scars as well as higher prevalence of HIV infection. The effect of homophily was higher among sex workers in indoor venues. However, it did not affect the estimated prevalence of HIV, even after using a post-stratification by workplace procedure. CONCLUSIONS The findings suggest that strategies should focus on extending access to, and utilization of, health services. Prevention policies should be specifically aimed at street workers. Regarding the application of Respondent-Driven Sampling, the sample should be sufficient to estimate transition probabilities, as the network develops more quickly among sex workers in indoor venues. PMID:25119937

Respondent driven sampling is an effective method for engaging methamphetamine users in HIV prevention research in South Africa

PubMed Central

Kimani, Stephen M.; Watt, Melissa H.; Merli, M. Giovanna; Skinner, Donald; Myers, Bronwyn; Pieterse, Desiree; MacFarlane, Jessica C.; Meade, Christina S.

2014-01-01

Background South Africa, in the midst of the world’s largest HIV epidemic, has a growing methamphetamine problem. Respondent driven sampling (RDS) is a useful tool for recruiting hard-to-reach populations in HIV prevention research, but its use with methamphetamine smokers in South Africa has not been described. This study examined the effectiveness of RDS as a method for engaging methamphetamine users in a Cape Town township into HIV behavioral research. Methods Standard RDS procedures were used to recruit active methamphetamine smokers from a racially diverse peri-urban township in Cape Town. Effectiveness of RDS was determined by examining social network characteristics (network size, homophily, and equilibrium) of recruited participants. Results Beginning with 8 seeds, 345 methamphetamine users were enrolled over 6 months, with a coupon return rate of 67%. The sample included 197 men and 148 women who were racially diverse (73% Coloured, 27% Black African) and had a mean age of 28.8 years (SD=7.2). Social networks were adequate (mean network size >5) and mainly comprised of close social ties. Equilibrium on race was reached after 11 waves of recruitment, and after ≤3 waves for all other variables of interest. There was little to moderate preference for either in- or out-group recruiting in all subgroups. Conclusions Results suggest that RDS is an effective method for engaging methamphetamine users into HIV prevention research in South Africa. Additionally, RDS may be a useful strategy for seeking high-risk methamphetamine users for HIV testing and linkage to HIV care in this and other low resource settings. PMID:25128957

Sampling Key Populations for HIV Surveillance: Results From Eight Cross-Sectional Studies Using Respondent-Driven Sampling and Venue-Based Snowball Sampling

PubMed Central

Stahlman, Shauna; Hargreaves, James; Weir, Sharon; Edwards, Jessie; Rice, Brian; Kochelani, Duncan; Mavimbela, Mpumelelo; Baral, Stefan

2017-01-01

Background In using regularly collected or existing surveillance data to characterize engagement in human immunodeficiency virus (HIV) services among marginalized populations, differences in sampling methods may produce different pictures of the target population and may therefore result in different priorities for response. Objective The objective of this study was to use existing data to evaluate the sample distribution of eight studies of female sex workers (FSW) and men who have sex with men (MSM), who were recruited using different sampling approaches in two locations within Sub-Saharan Africa: Manzini, Swaziland and Yaoundé, Cameroon. Methods MSM and FSW participants were recruited using either respondent-driven sampling (RDS) or venue-based snowball sampling. Recruitment took place between 2011 and 2016. Participants at each study site were administered a face-to-face survey to assess sociodemographics, along with the prevalence of self-reported HIV status, frequency of HIV testing, stigma, and other HIV-related characteristics. Crude and RDS-adjusted prevalence estimates were calculated. Crude prevalence estimates from the venue-based snowball samples were compared with the overlap of the RDS-adjusted prevalence estimates, between both FSW and MSM in Cameroon and Swaziland. Results RDS samples tended to be younger (MSM aged 18-21 years in Swaziland: 47.6% [139/310] in RDS vs 24.3% [42/173] in Snowball, in Cameroon: 47.9% [99/306] in RDS vs 20.1% [52/259] in Snowball; FSW aged 18-21 years in Swaziland 42.5% [82/325] in RDS vs 8.0% [20/249] in Snowball; in Cameroon 15.6% [75/576] in RDS vs 8.1% [25/306] in Snowball). They were less educated (MSM: primary school completed or less in Swaziland 42.6% [109/310] in RDS vs 4.0% [7/173] in Snowball, in Cameroon 46.2% [138/306] in RDS vs 14.3% [37/259] in Snowball; FSW: primary school completed or less in Swaziland 86.6% [281/325] in RDS vs 23.9% [59/247] in Snowball, in Cameroon 87.4% [520/576] in RDS vs 77.5% [238/307] in Snowball) than the snowball samples. In addition, RDS samples indicated lower exposure to HIV prevention information, less knowledge about HIV prevention, limited access to HIV prevention tools such as condoms, and less-reported frequency of sexually transmitted infections (STI) and HIV testing as compared with the venue-based samples. Findings pertaining to the level of disclosure of sexual practices and sexual practice–related stigma were mixed. Conclusions Samples generated by RDS and venue-based snowball sampling produced significantly different prevalence estimates of several important characteristics. These findings are tempered by limitations to the application of both approaches in practice. Ultimately, these findings provide further context for understanding existing surveillance data and how differences in methods of sampling can influence both the type of individuals captured and whether or not these individuals are representative of the larger target population. These data highlight the need to consider how program coverage estimates of marginalized populations are determined when characterizing the level of unmet need. PMID:29054832

HIV and STI control in El Salvador: results from an integrated behavioural survey among men who have sex with men.

PubMed

Creswell, Jacob; Guardado, Maria Elena; Lee, Janet; Nieto, Ana Isabel; Kim, Andrea A; Monterroso, Edgar; Paz-Bailey, Gabriela

2012-12-01

This cross-sectional study investigates HIV, other sexually transmitted infections (STI), and risk behaviours among men who have sex with men (MSM) in two cities in El Salvador. Respondent-driven sampling (RDS) was used to recruit MSM in the cities of San Salvador and San Miguel, El Salvador. Participants responded to questions about HIV risk behaviours; and blood, urine and anal swabs were collected. Blood samples were tested for herpes simplex type 2, syphilis and HIV infection. Urine and anal samples were tested by polymerase chain reaction (PCR) for Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium. HIV-positive samples were tested with the BED capture enzyme immunoassay to distinguish recent from longstanding HIV infection. We estimated population-adjusted prevalence of behavioural variables, STI and HIV, and identified risk factors for HIV. The final sample included 596 and 195 MSM in San Salvador and San Miguel, respectively. Consistent condom use was low across all partner types as was recent HIV testing. RDS-adjusted HIV prevalence was 10.8% (95% CI 7.4% to 14.7%) in San Salvador, and 8.8% (95% CI 4.2% to 14.5%) in San Miguel. The proportion of recent testing among HIV-positive samples was 20%. Prevalence of any bacterial STI by PRC testing was 12.7% (95% CI 8.2% to 17.5%) in San Salvador, and 9.6% (95% CI 4.9% to 15.4%) in San Miguel. We found a high prevalence of HIV, high levels of recent infection, and low condom usage. In El Salvador, targeted interventions towards MSM are needed to promote condom use, as well as to diagnose, treat and prevent HIV and other STIs.

Diverse HIV epidemics among people who inject drugs in Thailand: evidence from respondent-driven sampling surveys in Bangkok and Chiang Mai.

PubMed

Prybylski, Dimitri; Manopaiboon, Chomnad; Visavakum, Prin; Yongvanitjit, Kovit; Aramrattana, Apinun; Manomaipiboon, Parnrudee; Tanpradech, Suvimon; Suksripanich, Orapin; Pattanasin, Sarika; Wolfe, Mitchell; Whitehead, Sara J

2015-03-01

Thailand's long-standing HIV sero-sentinel surveillance system for people who inject drugs (PWID) is confined to those in methadone-based drug treatment clinics and representative data are scarce, especially outside of Bangkok. We conducted probability-based respondent-driven sampling (RDS) surveys in Bangkok (n=738) and Chiang Mai (n=309) to increase understanding of local HIV epidemics and to better inform the planning of evidence-based interventions. PWID had different epidemiological profiles in these two cities. Overall HIV prevalence was higher in Bangkok (23.6% vs. 10.9%, p<0.001) but PWID in Bangkok are older and appear to have long-standing HIV infections. In Chiang Mai, HIV infections appear to be more recently acquired and PWID were younger and had higher levels of recent injecting and sexual risk behaviors with lower levels of intervention exposure. Methamphetamine was the predominant drug injected in both sites and polydrug use was common although levels and patterns of the specific drugs injected varied significantly between the sites. In multivariate analysis, recent midazolam injection was significantly associated with HIV infection in Chiang Mai (adjusted odds ratio=8.1; 95% confidence interval: 1.2-54.5) whereas in Bangkok HIV status was not associated with recent risk behaviors as infections had likely been acquired in the past. PWID epidemics in Thailand are heterogeneous and driven by local factors. There is a need to customize intervention strategies for PWID in different settings and to integrate population-based survey methods such as RDS into routine surveillance to monitor the national response. Published by Elsevier Ireland Ltd.

Diverse HIV epidemics among people who inject drugs in Thailand: Evidence from respondent-driven sampling surveys in Bangkok and Chiang Mai☆

PubMed Central

Prybylski, Dimitri; Manopaiboon, Chomnad; Visavakum, Prin; Yongvanitjit, Kovit; Aramrattana, Apinun; Manomaipiboon, Parnrudee; Tanpradech, Suvimon; Suksripanich, Orapin; Pattanasin, Sarika; Wolfe, Mitchell; Whitehead, Sara J.

2016-01-01

Background Thailand’s long-standing HIV sero-sentinel surveillance system for people who inject drugs (PWID) is confined to those in methadone-based drug treatment clinics and representative data are scarce, especially outside of Bangkok. Methods We conducted probability-based respondent-driven sampling (RDS) surveys in Bangkok (n = 738) and Chiang Mai (n = 309) to increase understanding of local HIV epidemics and to better inform the planning of evidence-based interventions. Results PWID had different epidemiological profiles in these two cities. Overall HIV prevalence was higher in Bangkok (23.6% vs. 10.9%, p < 0.001) but PWID in Bangkok are older and appear to have long-standing HIV infections. In Chiang Mai, HIV infections appear to be more recently acquired and PWID were younger and had higher levels of recent injecting and sexual risk behaviors with lower levels of intervention exposure. Methamphetamine was the predominant drug injected in both sites and polydrug use was common although levels and patterns of the specific drugs injected varied significantly between the sites. In multivariate analysis, recent midazolam injection was significantly associated with HIV infection in Chiang Mai (adjusted odds ratio = 8.1; 95% confidence interval: 1.2–54.5) whereas in Bangkok HIV status was not associated with recent risk behaviors as infections had likely been acquired in the past. Conclusion PWID epidemics in Thailand are heterogeneous and driven by local factors. There is a need to customize intervention strategies for PWID in different settings and to integrate population-based survey methods such as RDS into routine surveillance to monitor the national response. PMID:25640153

Hepatitis B in Moroccan-Dutch: a quantitative study into determinants of screening participation.

PubMed

Hamdiui, Nora; Stein, Mart L; Timen, Aura; Timmermans, Danielle; Wong, Albert; van den Muijsenbergh, Maria E T C; van Steenbergen, Jim E

2018-03-29

In November 2016, the Dutch Health Council recommended hepatitis B (HBV) screening for first-generation immigrants from HBV endemic countries. However, these communities show relatively low attendance rates for screening programmes, and our knowledge on their participation behaviour is limited. We identified determinants associated with the intention to request an HBV screening test in first-generation Moroccan-Dutch immigrants. We also investigated the influence of non-refundable costs for HBV screening on their intention. Offline and online questionnaires were distributed among first- and second/third-generation Moroccan-Dutch immigrants using respondent-driven sampling. Random forest analyses were conducted to determine which determinants had the greatest impact on (1) the intention to request an HBV screening test on one's own initiative, and (2) the intention to participate in non-refundable HBV screening at €70,-. Of the 379 Moroccan-Dutch respondents, 49.3% intended to request a test on their own initiative, and 44.1% were willing to attend non-refundable screening for €70,-. Clarity regarding infection status, not having symptoms, fatalism, perceived self-efficacy, and perceived risk of having HBV were the strongest predictors to request a test. Shame and stigma, fatalism, perceived burden of screening participation, and social influence of Islamic religious leaders had the greatest predictive value for not intending to participate in screening at €70,- non-refundable costs. Perceived severity and possible health benefit were facilitators for this intention measure. These predictions were satisfyingly accurate, as the random forest method retrieved area under the curve scores of 0.72 for intention to request a test and 0.67 for intention to participate in screening at €70,- non-refundable costs. By the use of respondent-driven sampling, we succeeded in studying screening behaviour among a hard-to-reach minority population. Despite the limitations associated with correlated data and the sampling method, we recommend to (1) incorporate clarity regarding HBV status, (2) stress the risk of an asymptomatic infection, (3) emphasise mother-to-child transmission as the main transmission route, and (4) team up with Islamic religious leaders to help decrease elements of fatalism, shame, and stigma to enhance screening uptake of Moroccan immigrants in the Netherlands.

HIV, syphilis and sexual risk behaviours among men who have sex with men in Agadir and Marrakesh, Morocco.

PubMed

Johnston, Lisa Grazina; Alami, Kamal; El Rhilani, M Houssine; Karkouri, Mehdi; Mellouk, Othoman; Abadie, Alise; Rafif, Nadia; Ouarsas, Lahoucine; Bennani, Aziza; El Omari, Boutaina

2013-11-01

To collect baseline measurements of HIV and syphilis prevalence and sexual risk behaviours among men who have sex with men (MSM) in Agadir and Marrakech, Morocco, and provide strategic information to improve outreach programmes. Respondent-driven sampling was used to recruit men who reported having anal sex with another man in the last 6 months, aged 18 years and older and living in either Agadir or Marrakech for the past 6 months, regardless of nationality. Data were analysed with the multiplicity estimator using respondent-driven sampling analysis tool V.6.0. 323 MSM in Agadir and 346 in Marrakech were recruited into the survey. Most MSM in both cities reported being < 25 years, being unemployed, bisexual and in a couple with both a man and a woman. Most reported selling sex and having sex with women. HIV prevalence was 5.6% in Agadir and 2.8% in Marrakesh; syphilis was 7.0% in Agadir and 10.8% in Marrakesh. Among MSM who tested positive for HIV, 31.6% in Agadir and 56.4% in Marrakesh were co-infected with syphilis. HIV and syphilis findings coupled with high risk activities indicate the need for expanding programmes targeting MSM throughout Morocco. Selling sex and sex with women may be a strategy to cope with extreme stigma towards MSM. Criminalisation and discrimination of MSM in Morocco underscores the urgent need for long-term and sustainable risk reduction through legal reforms and promotion and protection of human rights.

Intimate Partner Violence and HIV Sexual Risk Behaviour Among Women Who Inject Drugs in Indonesia: A Respondent-Driven Sampling Study.

PubMed

Stoicescu, Claudia; Cluver, Lucie D; Spreckelsen, Thees; Casale, Marisa; Sudewo, Anindita Gabriella; Irwanto

2018-06-11

Women who inject drugs are disproportionately affected by HIV and intimate partner violence (IPV); however, the link between IPV and HIV remains under-researched among substance-using women in low- and middle-income countries. This study examined associations and additive effects of different forms of IPV victimization (psychological, physical and/or injurious, and sexual) on HIV sexual risk behavior among women who inject drugs in Indonesia. Respondent-driven sampling (RDS) was used to recruit 731 women from Greater Jakarta and Bandung, West Java. RDS-II weighted prevalence of any past-year IPV was 68.9% (95% CI 65.0, 72.6) in Jakarta and 55.9% (95% CI 48.0, 63.5) in Bandung. In separate logistic regressions controlling for socio-demographic covariates, all three forms of IPV showed statistically significant associations with sexual risk behavior. After adjusting for all IPV types, psychological (OR 1.87; 95% CI 1.17, 2.99; p = 0.009) and sexual (OR 1.98; 95% CI 1.22, 3.21; p = 0.006) IPV independently predicted women's sexual risk behavior. Marginal effects models suggested that co-occurrence of multiple forms of IPV had greater adverse consequences: sexual risk behavior was reported by 64.1% of women who did not experience any IPV, but increased to 89.9% among women exposed to all three types. Comprehensive harm reduction services that integrate IPV monitoring and prevention are urgently needed to reduce both HIV and IPV.

Unexpectedly high HIV prevalence among female sex workers in Bangkok, Thailand in a respondent-driven sampling survey.

PubMed

Manopaiboon, C; Prybylski, D; Subhachaturas, W; Tanpradech, S; Suksripanich, O; Siangphoe, U; Johnston, L G; Akarasewi, P; Anand, A; Fox, K K; Whitehead, S J

2013-01-01

The pattern of sex work in Thailand has shifted substantially over the last two decades from direct commercial establishments to indirect venues and non-venue-based settings. This respondent-driven sampling survey was conducted in Bangkok in 2007 among female sex workers (FSW) in non-venue-based settings to pilot a new approach to surveillance among this hidden population. Fifteen initial participants recruited 707 consenting participants who completed a behavioural questionnaire, and provided oral fluid for HIV testing, and urine for sexually transmitted infection (STI) testing. Overall HIV prevalence was 20.2% (95% confidence interval [CI] 16.3-24.7). Three-quarters of women were street-based (75.8%, 95% CI 69.9-81.1) who had an especially high HIV prevalence (22.7%, 95% CI 18.2-28.4); about 10 times higher than that found in routine sentinel surveillance among venue-based FSW (2.5%). STI prevalence (Chlamydia trachomatis and Neisseria gonorrhoeae) was 8.7% (95% CI 6.4-10.8) and 1.0% (95% CI 0.2-1.9), respectively. Lower price per sex act and a current STI infection were independently associated with HIV infection (P < 0.05). High HIV prevalence found among FSW participating in the survey, particularly non-venue-based FSW, identifies need for further prevention efforts. In addition, it identifies a higher-risk segment of FSW not reached through routine sentinel surveillance but accessible through this survey method.

[A respondent-driven sampling survey on HIV and risk factors among men who have sex with men in Chongqing].

PubMed

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.

Sexual Health of Trans Men Who Are Gay, Bisexual, or Who Have Sex with Men: Results from Ontario, Canada

PubMed Central

Redman, Nik; Bradley, Kaitlin; Scheim, Ayden I.

2013-01-01

ABSTRACT Recent reports have addressed the sexual health of female-to-male transgender or transsexual people who are gay, bisexual, and/or have sex with men (trans GB-MSM) using urban convenience samples. The Trans PULSE Project conducted a multimode, respondent-driven sampling survey in Ontario, Canada, in 2009–2010. Weighted estimates were calculated for trans GB-MSM (n = 173) for sexual orientation, behavior, partners, and HIV-related risk, as well as for psychosocial stressors and sexual satisfaction. An estimated 63.3% (95% CI [50.4, 73.5]) of trans men were GB-MSM (173/227). Results indicate great diversity in sexual behavior and experiences. Implications for sexual health promotion, counseling, and medical care are addressed. PMID:24971043

Sampling Key Populations for HIV Surveillance: Results From Eight Cross-Sectional Studies Using Respondent-Driven Sampling and Venue-Based Snowball Sampling.

PubMed

Rao, Amrita; Stahlman, Shauna; Hargreaves, James; Weir, Sharon; Edwards, Jessie; Rice, Brian; Kochelani, Duncan; Mavimbela, Mpumelelo; Baral, Stefan

2017-10-20

In using regularly collected or existing surveillance data to characterize engagement in human immunodeficiency virus (HIV) services among marginalized populations, differences in sampling methods may produce different pictures of the target population and may therefore result in different priorities for response. The objective of this study was to use existing data to evaluate the sample distribution of eight studies of female sex workers (FSW) and men who have sex with men (MSM), who were recruited using different sampling approaches in two locations within Sub-Saharan Africa: Manzini, Swaziland and Yaoundé, Cameroon. MSM and FSW participants were recruited using either respondent-driven sampling (RDS) or venue-based snowball sampling. Recruitment took place between 2011 and 2016. Participants at each study site were administered a face-to-face survey to assess sociodemographics, along with the prevalence of self-reported HIV status, frequency of HIV testing, stigma, and other HIV-related characteristics. Crude and RDS-adjusted prevalence estimates were calculated. Crude prevalence estimates from the venue-based snowball samples were compared with the overlap of the RDS-adjusted prevalence estimates, between both FSW and MSM in Cameroon and Swaziland. RDS samples tended to be younger (MSM aged 18-21 years in Swaziland: 47.6% [139/310] in RDS vs 24.3% [42/173] in Snowball, in Cameroon: 47.9% [99/306] in RDS vs 20.1% [52/259] in Snowball; FSW aged 18-21 years in Swaziland 42.5% [82/325] in RDS vs 8.0% [20/249] in Snowball; in Cameroon 15.6% [75/576] in RDS vs 8.1% [25/306] in Snowball). They were less educated (MSM: primary school completed or less in Swaziland 42.6% [109/310] in RDS vs 4.0% [7/173] in Snowball, in Cameroon 46.2% [138/306] in RDS vs 14.3% [37/259] in Snowball; FSW: primary school completed or less in Swaziland 86.6% [281/325] in RDS vs 23.9% [59/247] in Snowball, in Cameroon 87.4% [520/576] in RDS vs 77.5% [238/307] in Snowball) than the snowball samples. In addition, RDS samples indicated lower exposure to HIV prevention information, less knowledge about HIV prevention, limited access to HIV prevention tools such as condoms, and less-reported frequency of sexually transmitted infections (STI) and HIV testing as compared with the venue-based samples. Findings pertaining to the level of disclosure of sexual practices and sexual practice-related stigma were mixed. Samples generated by RDS and venue-based snowball sampling produced significantly different prevalence estimates of several important characteristics. These findings are tempered by limitations to the application of both approaches in practice. Ultimately, these findings provide further context for understanding existing surveillance data and how differences in methods of sampling can influence both the type of individuals captured and whether or not these individuals are representative of the larger target population. These data highlight the need to consider how program coverage estimates of marginalized populations are determined when characterizing the level of unmet need. ©Amrita Rao, Shauna Stahlman, James Hargreaves, Sharon Weir, Jessie Edwards, Duncan Kochelani, Duncan Kochelani, Mpumelelo Mavimbela, Stefan Baral. Originally published in JMIR Public Health and Surveillance (http://publichealth.jmir.org), 20.10.2017.

Effects of within-Class Differences in Sample Responding on Acquired Sample Equivalence

ERIC Educational Resources Information Center

Urcuioli, Peter J.; Vasconcelos, Maarco

2008-01-01

Two experiments examined whether acquired sample equivalence in many-to-one matching was affected by variation in sample-response requirements. In each experiment, pigeons responded on either identical or different response schedules to the sample stimuli that occasioned the same reinforced comparison choice (i.e., to the within-class samples).…

Mind the gap: implementation challenges break the link between HIV/AIDS research and practice.

PubMed

MacCarthy, Sarah; Reisner, Sari; Hoffmann, Michael; Perez-Brumer, Amaya; Silva-Santisteban, Alfonso; Nunn, Amy; Bastos, Leonardo; Vasconcellos, Mauricio Teixeira Leite de; Kerr, Ligia; Bastos, Francisco Inácio; Dourado, Inês

2016-11-03

Sampling strategies such as respondent-driven sampling (RDS) and time-location sampling (TLS) offer unique opportunities to access key populations such as men who have sex with men (MSM) and transgender women. Limited work has assessed implementation challenges of these methods. Overcoming implementation challenges can improve research quality and increase uptake of HIV services among key populations. Drawing from studies using RDS in Brazil and TLS in Peru, we summarize challenges encountered in the field and potential strategies to address them. In Brazil, study site selection, cash incentives, and seed selection challenged RDS implementation with MSM. In Peru, expansive geography, safety concerns, and time required for study participation complicated TLS implementation with MSM and transgender women. Formative research, meaningful participation of key populations across stages of research, and transparency in study design are needed to link HIV/AIDS research and practice. Addressing implementation challenges can close gaps in accessing services among those most burdened by the epidemic.

Mind the gap: implementation challenges break the link between HIV/AIDS research and practice

PubMed Central

MacCarthy, Sarah; Reisner, Sari; Hoffmann, Michael; Perez-Brumer, Amaya; Silva-Santisteban, Alfonso; Nunn, Amy; Bastos, Leonardo; de Vasconcellos, Mauricio Teixeira Leite; Kerr, Ligia; Bastos, Francisco Inácio; Dourado, Inês

2018-01-01

Sampling strategies such as respondent-driven sampling (RDS) and time-location sampling (TLS) offer unique opportunities to access key populations such as men who have sex with men (MSM) and transgender women. Limited work has assessed implementation challenges of these methods. Overcoming implementation challenges can improve research quality and increase uptake of HIV services among key populations. Drawing from studies using RDS in Brazil and TLS in Peru, we summarize challenges encountered in the field and potential strategies to address them. In Brazil, study site selection, cash incentives, and seed selection challenged RDS implementation with MSM. In Peru, expansive geography, safety concerns, and time required for study participation complicated TLS implementation with MSM and transgender women. Formative research, meaningful participation of key populations across stages of research, and transparency in study design are needed to link HIV/AIDS research and practice. Addressing implementation challenges can close gaps in accessing services among those most burdened by the epidemic. PMID:27828609

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

PubMed

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 guiding HCV elimination. However, future studies should report the operational conduct of each survey in accordance with the STROBE-RDS checklist to indicate sensitivity to the theoretical assumptions underlying the method. PROSPERO CRD42015019245.

Hepatitis C serosorting among people who inject drugs in rural Puerto Rico.

PubMed

Duncan, Ian; Curtis, Ric; Reyes, Juan Carlos; Abadie, Roberto; Khan, Bilal; Dombrowski, Kirk

2017-06-01

Due to the high cost of treatment, preventative measures to limit Hepatitis C (HCV) transmission among people who inject drugs (PWID) are encouraged by many public health officials. A key one of these is serosorting, where PWID select risk partners based on concordant HCV status. Research on the general U.S. population by Smith et al. (2013) found that knowledge of one's own HCV status facilitated serosorting behaviors among PWID, such that respondents with knowledge of their own status were more likely to ask potential partners about their status prior to sharing risk. Our objective was to see if this held true in rural Puerto Rico. We replicate this study using a sample of PWID in rural Puerto Rico to draw comparisons. We used respondent driven sampling to survey 315 participants, and have a final analytic sample of 154. The survey was heavily modeled after the National HIV Behavioral Survey, which was the dataset used by the previous researchers. We found that among PWID in rural Puerto Rico, unlike in the general population, knowledge of one's own HCV status had no significant effect on the selection of one's most recent injection partner, based on his/her HCV status. We conclude that PWID in rural Puerto Rico differ from the general U.S. population when it comes to serosorting behaviors, and that these differences should be taken into account in future outreaches and intervention strategies.

The development and validation of static and adaptive screeners to measure the severity of panic disorder, social anxiety disorder, and obsessive compulsive disorder.

PubMed

Sunderland, Matthew; Batterham, Philip J; Calear, Alison L; Carragher, Natacha

2017-12-01

A series of static and adaptive screeners for panic disorder, social anxiety disorder (SAD), and obsessive compulsive disorder (OCD) were developed and compared using data-driven methods to facilitate the measurement of each disorder in community samples. Data comprised 3175 respondents for the development sample and 3755 respondents for the validation sample, recruited independently using Facebook advertising. Item Response Theory (IRT) was utilized to develop static continuous screeners and to simulate computerized adaptive algorithms. The screeners consisted of a small subset of items from each bank (79% reduction in items for panic disorder, 85% reduction in items for SAD, and 84% reduction in items for OCD) that provided similar scores (r = 0.88-0.96). Both static and adaptive screeners were valid with respect to existing scales that purportedly measure similar constructs (r > 0.70 for panic disorder, r > 0.76 for SAD, and r > 0.68 for OCD). The adaptive scales were able to maintain a higher level of precision in comparison to the static scales and evidenced slightly higher concordance with scores generated by the full item banks. The screeners for panic disorder, SAD, and OCD could be used as a flexible approach to measure and monitor the severity of psychopathology in tailored treatment protocols. Copyright © 2017 John Wiley & Sons, Ltd.

Sexting among young adults.

PubMed

Gordon-Messer, Deborah; Bauermeister, Jose Arturo; Grodzinski, Alison; Zimmerman, Marc

2013-03-01

Sexting has stirred debate over its legality and safety, but few researchers have documented the relationship between sexting and health. We describe the sexting behavior of young adults in the United States, and examine its association with sexual behavior and psychological well-being. Using an adapted Web version of respondent-driven sampling, we recruited a sample of U.S. young adults (aged 18-24 years, N = 3,447). We examined participant sexting behavior using four categories of sexting: (1) nonsexters, (2) receivers, (3) senders, and (4) two-way sexters. We then assessed the relationships between sexting categories and sociodemographic characteristics, sexual behavior, and psychological well-being. More than half (57%) of the respondents were nonsexters, 28.2% were two-way sexters, 12.6% were receivers, and 2% were senders. Male respondents were more likely to be receivers than their female counterparts. Sexually active respondents were more likely to be two-way sexters than non-sexually active ones. Among participants who were sexually active in the past 30 days, we found no differences across sexting groups in the number of sexual partners or the number of unprotected sex partners in the past 30 days. We also found no relationship between sexting and psychological well-being. Our results suggest that sexting is not related to sexual risk behavior or psychological well-being. We discuss the findings of this study and propose directions for further research on sexting. Copyright © 2013 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

The Cost-Effectiveness of Cervical Self-Sampling to Improve Routine Cervical Cancer Screening: The Importance of Respondent Screening History and Compliance.

PubMed

Burger, Emily A; Sy, Stephen; Nygård, Mari; Kim, Jane J

2017-01-01

Human papillomavirus (HPV) testing allows women to self-collect cervico-vaginal cells at home (i.e., self-sampling). Using primary data from a randomized pilot study, we evaluated the long-term consequences and cost-effectiveness of using self-sampling to improve participation to routine cervical cancer screening in Norway. We compared a strategy reflecting screening participation (using reminder letters) to strategies that involved mailing self-sampling device kits to women noncompliant to screening within a 5- or 10-year period under two scenarios: (A) self-sampling respondents had moderate under-screening histories, or (B) respondents to self-sampling had moderate and severe under-screening histories. Model outcomes included quality-adjusted life-years (QALY) and lifetime costs. The "most cost-effective" strategy was identified as the strategy just below $100,000 per QALY gained. Mailing self-sampling device kits to all women noncompliant to screening within a 5- or 10-year period can be more effective and less costly than the current reminder letter policy; however, the optimal self-sampling strategy was dependent on the profile of self-sampling respondents. For example, "10-yearly self-sampling" is preferred ($95,500 per QALY gained) if "5-yearly self-sampling" could only attract moderate under-screeners; however, "5-yearly self-sampling" is preferred if this strategy could additionally attract severe under-screeners. Targeted self-sampling of noncompliers likely represents good value-for-money; however, the preferred strategy is contingent on the screening histories and compliance of respondents. The magnitude of the health benefit and optimal self-sampling strategy is dependent on the profile and behavior of respondents. Health authorities should understand these factors prior to selecting and implementing a self-sampling policy. Cancer Epidemiol Biomarkers Prev; 26(1); 95-103. ©2016 AACR. ©2016 American Association for Cancer Research.

Balancing theory and practice in respondent-driven sampling: a case study of innovations developed to overcome recruitment challenges.

PubMed

Truong, Hong-Ha M; Grasso, Michael; Chen, Yea-Hung; Kellogg, Timothy A; Robertson, Tyler; Curotto, Alberto; Steward, Wayne T; McFarland, Willi

2013-01-01

Respondent-driven sampling (RDS) offers a recruitment strategy for hard-to-reach populations. However, RDS faces logistical and theoretical challenges that threaten efficiency and validity in settings worldwide. We present innovative adaptations to conventional RDS to overcome barriers encountered in recruiting a large, representative sample of men who have sex with men (MSM) who travel internationally. Novel methodological adaptations for the "International Travel Research to Inform Prevention" or "I-TRIP" study were offering participants a choice between electronic and paper coupons referrals for recruitment and modifying the secondary incentives structure from small cash amounts to raffle entries for periodic large cash prize raffle drawings. Staged referral limit increases from 3 to 10 referrals and progressive addition of 70 seeds were also implemented. There were 501 participants enrolled in up to 13 waves of growth. Among participants with a choice of referral methods, 81% selected electronic referrals. Of participants who were recruited electronically, 90% chose to remain with electronic referrals when it was their turn to recruit. The mean number of enrolled referrals was 0.91 for electronic referrals compared to 0.56 for paper coupons. Median referral lag time, i.e., the time interval between when recruiters were given their referrals and when a referred individual enrolled in the study, was 20 days (IQR 10-40) for electronic referrals, 20 days (IQR 8-58) for paper coupons, 20 days (IQR 10-41) for raffle entries and 33 days (IQR 16-148) for small cash incentives. The recruitment of MSM who travel internationally required maximizing known flexible tools of RDS while at the same time necessitating innovations to increase recruitment efficiency. Electronic referrals emerged as a major advantage in recruiting this hard-to-reach population who are of high socio-economic status, geographically diffuse and highly mobile. These enhancements may improve the performance of RDS in target populations with similar characteristics.

Using Respondent Driven Sampling to Identify Malaria Risks and Occupational Networks among Migrant Workers in Ranong, Thailand

PubMed Central

Wangroongsarb, Piyaporn; Hwang, Jimee; Thwing, Julie; Karuchit, Samart; Kumpetch, Suthon; Rand, Alison; Drakeley, Chris; MacArthur, John R.; Kachur, S. Patrick; Satimai, Wichai; Meek, Sylvia; Sintasath, David M.

2016-01-01

Background Ranong Province in southern Thailand is one of the primary entry points for migrants entering Thailand from Myanmar, and borders Kawthaung Township in Myanmar where artemisinin resistance in malaria parasites has been detected. Areas of high population movement could increase the risk of spread of artemisinin resistance in this region and beyond. Methods A respondent-driven sampling (RDS) methodology was used to compare migrant populations coming from Myanmar in urban (Site 1) vs. rural (Site 2) settings in Ranong, Thailand. The RDS methodology collected information on knowledge, attitudes, and practices for malaria, travel and occupational histories, as well as social network size and structure. Individuals enrolled were screened for malaria by microscopy, Real Time-PCR, and serology. Results A total of 619 participants were recruited in Ranong City and 623 participants in Kraburi, a rural sub-district. By PCR, a total of 14 (1.1%) samples were positive (2 P. falciparum in Site 1; 10 P. vivax, 1 Pf, and 1 P. malariae in Site 2). PCR analysis demonstrated an overall weighted prevalence of 0.5% (95% CI, 0–1.3%) in the urban site and 1.0% (95% CI, 0.5–1.7%) in the rural site for all parasite species. PCR positivity did not correlate with serological positivity; however, as expected there was a strong association between antibody prevalence and both age and exposure. Access to long-lasting insecticidal treated nets remains low despite relatively high reported traditional net use among these populations. Conclusions The low malaria prevalence, relatively smaller networks among migrants in rural settings, and limited frequency of travel to and from other areas of malaria transmission in Myanmar, suggest that the risk for the spread of artemisinin resistance from this area may be limited in these networks currently but may have implications for regional malaria elimination efforts. PMID:28033322

Investigation of alcohol-related social norms among youth aged 14–17 years in Perth, Western Australia: protocol for a respondent-driven sampling study

PubMed Central

Hildebrand, Janina; Maycock, Bruce; Howat, Peter; Burns, Sharyn; Allsop, Steve; Dhaliwal, Satvinder; Lobo, Roanna

2013-01-01

Introduction Alcohol use among young people is a major public health concern in Australia and internationally. Research elucidating social norms influencing alcohol use supports the desire to conform to peers. However, there is a lack of evidence on how social norms are transmitted from the community to young people and between family members and peers, as previous studies are limited to mainly school and university environments. This article describes the proposed process to investigate common alcohol-related norms held by 14-year-olds to 17-year-olds in Perth, Western Australia, and to clarify the process and pathways through which proalcohol norms are transmitted to adolescents. Methods and analysis This cross-sectional quantitative study will use respondent-driven sampling (RDS) to recruit a sample of 672 adolescents from sporting groups, youth programmes and the community in Perth. Data will be collected with a previously developed and validated multidimensional online survey instrument. A variety of strategies will be explored to aid participation including face-to-face recruitment and survey administration, web-based RDS and a ‘mature minor’ consent assessment protocol. Data analysis will include descriptive statistics of demographic characteristics, as well as social network and dyadic analyses, to explore the connections between shared understanding of norms and behaviours among individuals and how these translate into reported practices. Ethics and dissemination This research is expected to extend our understanding of normative development pathways to inform future interventions, and will be widely disseminated through conference presentations, peer-reviewed papers, media channels and community seminars. A study reference group of key health industry stakeholders will be established to encourage integration of study findings into policy and practice, and results will guide the development of community interventions. The Curtin University Human Research Ethics Committee has granted approval for this research. PMID:24154519

Respondent-driven sampling on the Thailand-Cambodia border. II. Knowledge, perception, practice and treatment-seeking behaviour of migrants in malaria endemic zones

PubMed Central

2011-01-01

Background Population movements along the Thailand-Cambodia border, particularly among highly mobile and hard-to-access migrant groups from Cambodia and Myanmar, are assumed to play a key role in the spread of artemisinin resistance. Data on treatment-seeking behaviours, knowledge and perceptions about malaria, and use of preventive measures is lacking as characteristics of this population prevent them from being represented in routine surveillance and the lack of a sampling frame makes reliable surveys challenging. Methods A survey of migrant populations from Cambodia and Myanmar was implemented in five selected rural locations in Thailand along the Thai-Cambodian border using respondent driven sampling (RDS) to determine demographic characteristics of the population, migratory patterns, knowledge about malaria, and health-care -seeking behaviours. Results The majority of migrants from Myanmar are long-term residents (98%) with no plans to move back to Myanmar, understand spoken Thai (77%) and can therefore benefit from health messages in Thai, have Thai health insurance (99%) and accessed public health services in Thailand (63%) for their last illness. In comparison, the majority of Cambodian migrants are short-term (72%). Of the short-term Cambodian migrants, 92% work in agriculture, 18% speak Thai, 3.4% have Thai health insurance, and the majority returned to Cambodia for treatment (45%), self-treated (11%), or did not seek treatment for their last illness (27%). Conclusion Most highly mobile migrants along the Thai-Cambodia border are not accessing health messages or health treatment in Thailand, increasing their risk of malaria and facilitating the spread of potentially resistant Plasmodium falciparum as they return to Cambodia to seek treatment. Reaching out to highly mobile migrants with health messaging they can understand and malaria diagnosis and treatment services they can access is imperative in the effort to contain the spread of artemisinin-resistant P. falciparum. PMID:21554711

Stress-Driven Melt Segregation and Organization in Partially Molten Rocks III: Annealing Experiments and Surface Tension-Driven Redistribution of Melt

NASA Astrophysics Data System (ADS)

Parsons, R.; Hustoft, J. W.; Holtzman, B. K.; Kohlstedt, D. L.; Phipps Morgan, J.

2004-12-01

As discussed in the two previous abstracts in this series, simple shear experiments on synthetic upper mantle-type rock samples reveal the segregation of melt into melt-rich bands separated by melt-depleted lenses. Here, we present new results from experiments designed to understand the driving forces working for and against melt segregation. To better understand the kinetics of surface tension-driven melt redistribution, we first deform samples at similar conditions (starting material, sample size, stress and strain) to produce melt-rich band networks that are statistically similar. Then the load is removed and the samples are statically annealed to allow surface tension to redistribute the melt-rich networks. Three samples of olivine + 20 vol% chromite + 4 vol% MORB were deformed at a confining pressure of 300 MPa and a temperature of 1523 K in simple shear at shear stresses of 20 - 55 MPa to shear strains of 3.5 and then statically annealed for 0, 10, or 100 h at the same P-T conditions. Melt-rich bands are fewer in number and appear more diffuse when compared to the deformed but not annealed samples. Bands with less melt tend to disappear more rapidly than more melt-rich ones. The melt fraction in the melt-rich bands decreased from 0.2 in the quenched sample to 0.1 in the sample annealed for 100 h. After deformation, the melt fraction in the melt-depleted regions are ~0.006; after static annealing for 100 h, this value increases to 0.02. These experiments provide new quantitative constraints on the kinetics of melt migration driven by surface tension. By quantifying this driving force in the same samples in which stress-driven distribution occurred, we learn about the relative kinetics of stress-driven melt segregation. The kinetics of both of these processes must be scaled together to mantle conditions to understand the importance of stress-driven melt segregation in the Earth, and to understand the interaction of this process with melt-rock reaction-driven processes.

Overlapping HIV and sex-work stigma among female sex workers recruited to 14 respondent-driven sampling surveys across Zimbabwe, 2013.

PubMed

Hargreaves, J R; Busza, J; Mushati, P; Fearon, E; Cowan, F M

2017-06-01

HIV stigma can inhibit uptake of HIV testing and antiretroviral therapy as well as negatively affect mental health. Efforts to reduce discrimination against people living with HIV (LWH) have contributed to greater acceptance of the infection. Female sex workers (FSW) LWH may experience overlapping stigma due to both their work and HIV status, although this is poorly understood. We examined HIV and sex-work stigma experienced by FSW LWH in Zimbabwe. Using the SAPPH-IRe cluster-randomised trial baseline survey, we analysed the data from 1039 FSW self-reporting HIV. The women were recruited in 14 sites using respondent-driven sampling. We asked five questions to assess internalised and experienced stigma related to working as a sex worker, and the same questions were asked in reference to HIV. Among all FSW, 91% reported some form of sex-work stigma. This was not associated with sociodemographic or sex-work characteristics. Rates of sex-work stigma were higher than those of HIV-related stigma. For example, 38% reported being "talked badly about" for LWH compared with 77% for their involvement in sex work. Those who reported any sex-work stigma also reported experiencing more HIV stigma compared to those who did not report sex-work stigma, suggesting a layering effect. FSW in Zimbabwe experience stigma for their role as "immoral" women and this appears more prevalent than HIV stigma. As HIV stigma attenuates, other forms of social stigma associated with the disease may persist and continue to pose barriers to effective care.

Do recruitment patterns of young men who have sex with men (YMSM) recruited through respondent-driven sampling (RDS) violate assumptions?

PubMed Central

Phillips, Gregory; Kuhns, Lisa M.; Garofalo, Rob; Mustanski, Brian

2014-01-01

Background In order to generate unbiased estimates for data collected using respondent-driven sampling (RDS), a number of assumptions need to be met: individuals recruit randomly from their social network and people can accurately report their eligible network size. However, research has shown that these assumptions are often violated. Methods This study used baseline data from Crew 450, a longitudinal study of young men who have sex with men in Chicago who were recruited via a modified form of RDS, and its network substudy, in which a subset of 175 participants reported details on the composition and characteristics of their social network at either one or two years post-baseline. Results Nearly two-thirds of participants reported giving coupons to at least one alter (64.0%), and 56.3% believed their alter(s) used the coupons. Frequency of communication, closeness, and type of relationship played a major role in determining coupon distribution. Participants whose alters used coupons were significantly less likely to describe the strength of their relationship as “not at all close” (OR = 0.08; 95% CI: 0.02, 0.36) compared to “very close” and to communicate weekly (OR = 0.20; 95% CI: 0.08, 0.49) or 1–6 times in the last 6 months (OR = 0.18; 95% CI: 0.06, 0.59). Conclusion Contrary to RDS assumptions, we found that relationship characteristics played a significant role when individuals decided to whom they would give coupons. PMID:25086159

High variability of HIV and HCV seroprevalence and risk behaviours among people who inject drugs: results from a cross-sectional study using respondent-driven sampling in eight German cities (2011-14).

PubMed

Wenz, Benjamin; Nielsen, Stine; Gassowski, Martyna; Santos-Hövener, Claudia; Cai, Wei; Ross, R Stefan; Bock, Claus-Thomas; Ratsch, Boris-Alexander; Kücherer, Claudia; Bannert, Norbert; Bremer, Viviane; Hamouda, Osamah; Marcus, Ulrich; Zimmermann, Ruth

2016-09-05

People who inject drugs (PWID) are at increased risk of acquiring and transmitting HIV and Hepatitis C (HCV) due to sharing injection paraphernalia and unprotected sex. To generate seroprevalence data on HIV and HCV among PWID and related data on risk behaviour, a multicentre sero- and behavioural survey using respondent driven sampling (RDS) was conducted in eight German cities between 2011 and 2014. We also evaluated the feasibility and effectiveness of RDS for recruiting PWID in the study cities. Eligible for participation were people who had injected drugs within the last 12 months, were 16 years or older, and who consumed in one of the study cities. Participants were recruited, using low-threshold drop-in facilities as study sites. Initial seeds were selected to represent various sub-groups of people who inject drugs (PWID). Participants completed a face-to-face interview with a structured questionnaire about socio-demographics, sexual and injecting risk behaviours, as well as the utilisation of health services. Capillary blood samples were collected as dried blood spots and were anonymously tested for serological and molecular markers of HIV and HCV. The results are shown as range of proportions (min. and max. values (%)) in the respective study cities. For evaluation of the sampling method we applied criteria from the STROBE guidelines. Overall, 2,077 PWID were recruited. The range of age medians was 29-41 years, 18.5-35.3 % of participants were female, and 9.2-30.6 % were foreign born. Median time span since first injection were 10-18 years. Injecting during the last 30 days was reported by 76.0-88.4 % of participants. Sharing needle/syringes (last 30 days) ranged between 4.7 and 22.3 %, while sharing unsterile paraphernalia (spoon, filter, water, last 30 days) was reported by 33.0-43.8 %. A majority of participants (72.8-85.8 %) reported incarceration at least once, and 17.8-39.8 % had injected while incarcerated. Between 30.8 and 66.2 % were currently in opioid substitution therapy. Unweighted HIV seroprevalence ranged from 0-9.1 %, HCV from 42.3-75.0 %, and HCV-RNA from 23.1-54.0 %. The implementation of RDS as a recruiting method in cooperation with low-threshold drop in facilities was well accepted by both staff and PWID. We reached our targeted sample size in seven of eight cities. In the recruited sample of mostly current injectors with a long duration of injecting drug use, seroprevalence for HIV and HCV varied greatly between the city samples. HCV was endemic among participants in all city samples. Our results demonstrate the necessity of intensified prevention strategies for blood-borne infections among PWID in Germany.

User-driven sampling strategies in image exploitation

NASA Astrophysics Data System (ADS)

Harvey, Neal; Porter, Reid

2013-12-01

Visual analytics and interactive machine learning both try to leverage the complementary strengths of humans and machines to solve complex data exploitation tasks. These fields overlap most significantly when training is involved: the visualization or machine learning tool improves over time by exploiting observations of the human-computer interaction. This paper focuses on one aspect of the human-computer interaction that we call user-driven sampling strategies. Unlike relevance feedback and active learning sampling strategies, where the computer selects which data to label at each iteration, we investigate situations where the user selects which data is to be labeled at each iteration. User-driven sampling strategies can emerge in many visual analytics applications but they have not been fully developed in machine learning. User-driven sampling strategies suggest new theoretical and practical research questions for both visualization science and machine learning. In this paper we identify and quantify the potential benefits of these strategies in a practical image analysis application. We find user-driven sampling strategies can sometimes provide significant performance gains by steering tools towards local minima that have lower error than tools trained with all of the data. In preliminary experiments we find these performance gains are particularly pronounced when the user is experienced with the tool and application domain.

76 FR 56141 - Notice of Intent To Request New Information Collection

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-12

... level surveys of similar scope and size. The sample for each selected community will be strategically... of 2 hours per sample community. Full Study: The maximum sample size for the full study is 2,812... questionnaires. The initial sample size for this phase of the research is 100 respondents (10 respondents per...

Data-Driven Sampling Matrix Boolean Optimization for Energy-Efficient Biomedical Signal Acquisition by Compressive Sensing.

PubMed

Wang, Yuhao; Li, Xin; Xu, Kai; Ren, Fengbo; Yu, Hao

2017-04-01

Compressive sensing is widely used in biomedical applications, and the sampling matrix plays a critical role on both quality and power consumption of signal acquisition. It projects a high-dimensional vector of data into a low-dimensional subspace by matrix-vector multiplication. An optimal sampling matrix can ensure accurate data reconstruction and/or high compression ratio. Most existing optimization methods can only produce real-valued embedding matrices that result in large energy consumption during data acquisition. In this paper, we propose an efficient method that finds an optimal Boolean sampling matrix in order to reduce the energy consumption. Compared to random Boolean embedding, our data-driven Boolean sampling matrix can improve the image recovery quality by 9 dB. Moreover, in terms of sampling hardware complexity, it reduces the energy consumption by 4.6× and the silicon area by 1.9× over the data-driven real-valued embedding.

The cost-effectiveness of cervical self-sampling to improve routine cervical cancer screening: The importance of respondent screening history and compliance

PubMed Central

Burger, Emily A; Sy, Stephen; Nygård, Mari; Kim, Jane J

2016-01-01

Background Human papillomavirus (HPV) testing allows women to self-collect cervico-vaginal cells at home (i.e., self-sampling). Using primary data from a randomized pilot study, we evaluated the long-term consequences and cost-effectiveness of using self-sampling to improve participation to routine cervical cancer screening in Norway. Methods We compared a strategy reflecting screening participation (using reminder letters) to strategies that involved mailing self-sampling device kits to women non-compliant to screening within a 5-year or 10-year period under two scenarios: A) self-sampling respondents had moderate under-screening histories, or B) respondents to self-sampling had moderate and severe under-screening histories. Model outcomes included quality-adjusted life-years (QALY) and lifetime costs. The ‘most cost-effective’ strategy was identified as the strategy just below $100,000 per QALY gained. Results Mailing self-sampling device kits to all women non-compliant to screening within a 5-year or 10-year period can be more effective and less costly than the current reminder letter policy; however, the optimal self-sampling strategy was dependent on the profile of self-sampling respondents. For example, ‘10-yearly self-sampling’ is preferred ($95,500 per QALY gained) if ‘5-yearly self-sampling’ could only attract moderate under-screeners; however, ‘5-yearly self-sampling’ is preferred if this strategy could additionally attract severe under-screeners. Conclusions Targeted self-sampling of non-compliers likely represents good value-for-money; however, the preferred strategy is contingent on the screening histories and compliance of respondents. Impact The magnitude of the health benefit and optimal self-sampling strategy is dependent on the profile and behavior of respondents. Health authorities should understand these factors prior to selecting and implementing a self-sampling policy. PMID:27624639

Attempted suicide among transgender persons: The influence of gender-based discrimination and victimization.

PubMed

Clements-Nolle, Kristen; Marx, Rani; Katz, Mitchell

2006-01-01

To determine the independent predictors of attempted suicide among transgender persons we interviewed 392 male-to-female (MTF) and 123 female-to-male (FTM) individuals. Participants were recruited through targeted sampling, respondent-driven sampling, and agency referrals in San Francisco. The prevalence of attempted suicide was 32% (95% CI = 28% to 36%). In multivariate logistic regression analysis younger age (<25 years), depression, a history of substance abuse treatment, a history of forced sex, gender-based discrimination, and gender-based victimization were independently associated with attempted suicide. Suicide prevention interventions for transgender persons are urgently needed, particularly for young people. Medical, mental health, and social service providers should address depression, substance abuse, and forced sex in an attempt to reduce suicidal behaviors among transgender persons. In addition, increasing societal acceptance of the transgender community and decreasing gender-based prejudice may help prevent suicide in this highly stigmatized population.

Network Structure and the Risk for HIV Transmission Among Rural Drug Users

PubMed Central

Young, A. M.; Jonas, A. B.; Mullins, U. L.; Halgin, D. S.

2012-01-01

Research suggests that structural properties of drug users’ social networks can have substantial effects on HIV risk. The purpose of this study was to investigate if the structural properties of Appalachian drug users’ risk networks could lend insight into the potential for HIV transmission in this population. Data from 503 drug users recruited through respondent-driven sampling were used to construct a sociometric risk network. Network ties represented relationships in which partners had engaged in unprotected sex and/or shared injection equipment. Compared to 1,000 randomly generated networks, the observed network was found to have a larger main component and exhibit more cohesiveness and centralization than would be expected at random. Thus, the risk network structure in this sample has many structural characteristics shown to be facilitative of HIV transmission. This underscores the importance of primary prevention in this population and prompts further investigation into the epidemiology of HIV in the region. PMID:23184464

Social Integration and Health: Community Involvement, Stigmatized Identities, and Sexual Risk in Latino Sexual Minorities

PubMed Central

Ramirez-Valles, Jesus; Kuhns, Lisa M.; Campbell, Richard T.; Diaz, Rafael M.

2013-01-01

The purpose of this study is to contribute to the conceptual understanding and practical application of social integration theory to health behaviors. We test whether community involvement in AIDS and GLBT organizations moderates the relationship of racial and homosexual stigmata to sexual risk behavior among gay and bisexual men and transgender persons of Latin American origin or descent. We use structural equation modeling to analyze data from a sample of 643 individuals recruited via respondent-driven sampling. Among those not involved in community organizations, homosexual and racial stigmata are related to sexual activity under the influence of alcohol and drugs, which is linked to sexual risk behavior. Among the involved group, the stigmata are not linked to sexual activity under the influence of alcohol and drugs, or to sexual risk behavior. The moderating role of community involvement seems to be more salient in those currently involved than those ever involved. PMID:20420293

Factors Associated with HIV Viral Load in a Respondent Driven Sample in Los Angeles

PubMed Central

King, WD; Larkins, S; Hucks-Ortiz, C; Wang, J; Gorbach, P; Veniegas, R; Shoptaw, S

2008-01-01

This study used a modified version of the Behavioral Model for Vulnerable Populations to examine the predisposing, enabling, and need factors associated with detectable viral load (VL). HIV status was measured using saliva and confirmed by blood. Of 835 persons enrolled, 193 were HIV positive and provided VL counts. A multistage logistic regression demonstrated that the predisposing factors of homelessness and recent substance abuse, particularly methamphetamine abuse, had a negative association with VL. The negative association of homelessness was lessened with the introduction of enabling and need utilization factors in the model. In contrast, the negative association with recent substance abuse on VL was sustained in the final model. Provision of HIV care and medications attenuated the negative association of homelessness within this sample. Guided policy to address substance abuse among those who are HIV positive is needed to improve biological outcomes. PMID:18064555

Sexual sensation seeking, transactional sex, and rural African American cocaine users

PubMed Central

Gullette, Donna; Booth, Brenda M.; Wright, Patricia B.; Montgomery, Brooke E. E.; Stewart, Katharine E.

2014-01-01

The purpose of this study was to explore correlates of sexual sensation seeking (SSS) in a sample of rural African American cocaine users. Respondent-driven sampling was used to recruit 251 participants from two impoverished rural counties in eastern Arkansas. Consistent with previous investigations, SSS scores were associated with being younger, being male, having more sexual partners, and having more unprotected sexual encounters in the previous 30 days. Multiple regression revealed SSS was correlated with number of oral sex acts, transactional sex (exchanging sex for food, shelter, drugs, money, or other commodities), and Addiction Severity Index (ASI) drug composite. SSS continues to demonstrate a strong association with sexual risk behaviors in diverse populations, including vulnerable groups like this community. Interventions to reduce unsafe sexual behaviors among high-risk groups, including drug users and individuals who engage in transactional sex, should incorporate approaches that include high sensation seekers' needs for novelty and variety. PMID:24070647

Impact of heat treatment on HSS cutting tool (ASTM A600) and its behaviour during machining of mild steel (ASTM A36)

NASA Astrophysics Data System (ADS)

Afolalu, S. A.; Abioye, O. P.; Salawu, E. Y.; Okokpujie, I. P.; Abioye, A. A.; Omotosho, O. A.; Ajayi., O. O.

2018-04-01

Carburization is one the best heat treatment that responded well to hardening with Palm Kernel Shell giving the best hardness value. This work studied the influence of carburization on HSStool(ASTM A600) and its behaviour during machining of mild steel (ASTM A36). Composition of the samples (12 pieces of 180 × 12 × 12 mm) HSS tools were checked using UV-VIS spectrometer and the tools were carburized with PKS at holding temperatures and time of 800, 850, 900, 950 °C and 60,90 120 minutes using muffle furnance. The micro structural analysis, surface and core hardnessof the treated samples gave better results than the untreated samples when checked withsoft driven and optical microscope. It wasalso observed that increase in the feed rate and depth for length of cut of 50 mm significantly reduces the wear progression and thereby gave best machining time at maximum carburizing temperature and time(950 °C / 120 minutes) when it was used to cut mild steelon the lathe machine.

The Where and How for Reaching Transgender Women and Men Who Have Sex with Men with HIV Prevention Services in Guatemala.

PubMed

Miller, William M; Miller, William C; Barrington, Clare; Weir, Sharon S; Chen, Sanny Y; Emch, Michael E; Pettifor, Audrey E; Paz-Bailey, Gabriela

2017-12-01

This study aims to describe the transgender women and men who have sex with men (MSM) missed through venue-based sampling and illustrate how data on venues can be used to prioritize service delivery. Respondent-driven sampling (RDS) and time-location sampling (TLS) were used concurrently in 2010 for behavioral surveillance among MSM and transgender women in Guatemala City. RDS recruits who did not frequent venues (n = 106) were compared to TLS recruits (n = 609). TLS participants recruited at different types of venues were compared. RDS recruits who did not frequent venues were less educated, less likely to identify as gay, more likely to have concurrent partners and female sexual partners. Participants recruited at NGOs, saunas, hotels, streets and parks had more partners, were more likely to receive money for sex or have concurrent partners. Prevention programs for MSM and transgender women should characterize social venues and people that frequent them and improve service coverage through venues and social networks.

Adolescent Sexual Debut and Initiation into New-Type Drug Use among a Sample of Young Adults

PubMed Central

Ding, Yingying; He, Na; Detels, Roger

2017-01-01

We examined the association between adolescent sexual debut and age at new-type drug initiation among a sample of young adult new-type drug users. A total of 276 participants were recruited using respondent-driven sampling (RDS) in Shanghai, China. The analyses were restricted to a total of 201 participants aged between 18 and 30 years. The average age at sexual debut and age at first new-type drug use were 18.8 and 20.9 years, respectively. About 94% of participants reported having sexual experience (n = 188); of those, 137 (72.9%) had sexual debut before they first used new-type drugs, while 32 (17.0%) initiated both events at the same age. After adjustment for age, income, education, and sexual orientation, adolescent sexual debut was independently associated with younger age at new-type drug initiation. Adolescent sexual debut is associated with early onset of new-type drug use. Our findings underscore the importance of implementing sex-education programs for adolescents in schools in China. PMID:26098832

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR REIMBURSEMENT FOR FIELD COLLECTION OF DIET SAMPLES (UA-F-23.1)

EPA Science Inventory

The purpose of this SOP is to provide a uniform procedure for the financial reimbursement of primary respondents for the collection of diet samples. Respondents were reimbursed for replicate food and beverage samples by type and amount collected over a 24-hour sampling period. ...

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR REIMBURSEMENT FOR FIELD COLLECTION OF FOOD SAMPLES (UA-F-23.1)

EPA Science Inventory

The purpose of this SOP is to provide a uniform procedure for the financial reimbursement of primary respondents for the collection of diet samples. Respondents were reimbursed for replicate food and beverage samples by type and amount collected over a 24-hour sampling period. ...

Approaches to Recruiting 'Hard-To-Reach' Populations into Re-search: A Review of the Literature.

PubMed

Shaghaghi, Abdolreza; Bhopal, Raj S; Sheikh, Aziz

2011-01-01

'Hard-to-reach' is a term used to describe those sub-groups of the population that may be difficult to reach or involve in research or public health programmes. Application of a single term to call these sub-sections of populations implies a homogeneity within distinct groups, which does not necessarily exist. Different sampling techniques were introduced so far to recruit hard-to-reach populations. In this article, we have reviewed a range of ap-proaches that have been used to widen participation in studies. We performed a Pubmed and Google search for relevant English language articles using the keywords and phrases: (hard-to-reach AND population* OR sampl*), (hidden AND population* OR sample*) and ("hard to reach" AND population* OR sample*) and a consul-tation of the retrieved articles' bibliographies to extract empirical evidence from publications that discussed or examined the use of sampling techniques to recruit hidden or hard-to-reach populations in health studies. Reviewing the literature has identified a range of techniques to recruit hard-to-reach populations, including snowball sampling, respondent-driven sampling (RDS), indigenous field worker sampling (IFWS), facility-based sampling (FBS), targeted sampling (TS), time-location (space) sampling (TLS), conventional cluster sampling (CCS) and capture re-capture sampling (CR). The degree of compliance with a study by a certain 'hard-to-reach' group de-pends on the characteristics of that group, recruitment technique used and the subject of inter-est. Irrespective of potential advantages or limitations of the recruitment techniques reviewed, their successful use depends mainly upon our knowledge about specific characteristics of the target populations. Thus in line with attempts to expand the current boundaries of our know-ledge about recruitment techniques in health studies and their applications in varying situa-tions, we should also focus on possibly all contributing factors which may have an impact on participation rate within a defined population group.

Evaluating outcome-correlated recruitment and geographic recruitment bias in a respondent-driven sample of people who inject drugs in Tijuana, Mexico

PubMed Central

Rudolph, Abby E.; Gaines, Tommi L.; Lozada, Remedios; Vera, Alicia; Brouwer, Kimberly C.

2015-01-01

Respondent-driven sampling’s (RDS) widespread use and reliance on untested assumptions suggests a need for new exploratory/diagnostic tests. We assessed geographic recruitment bias and outcome-correlated recruitment among 1048 RDS-recruited people who inject drugs (Tijuana, Mexico). Surveys gathered demographics, drug/sex behaviors, activity locations, and recruiter-recruit pairs. Simulations assessed geographic and network clustering of active syphilis (RPR titers≥1:8). Gender-specific predicted probabilities were estimated using logistic regression with GEE and robust standard errors. Active syphilis prevalence was 7% (crude: men=5.7% and women=16.6%; RDS-adjusted: men=6.7% and women=7.6%). Syphilis clustered in the Zona Norte, a neighborhood known for drug and sex markets. Network simulations revealed geographic recruitment bias and non-random recruitment by syphilis status. Gender-specific prevalence estimates accounting for clustering were highest among those living/working/injecting/buying drugs in the Zona Norte and directly/indirectly connected to syphilis cases (men:15.9%, women:25.6%) and lowest among those with neither exposure (men:3.0%, women:6.1%). Future RDS analyses should assess/account for network and spatial dependencies. PMID:24969586

Harnessing Social Networks along with Consumer-Driven Electronic Communication Technologies to Identify and Engage Members of 'Hard-to-Reach' Populations: A Methodological Case Report

PubMed Central

2010-01-01

Background Sampling in the absence of accurate or comprehensive information routinely poses logistical, ethical, and resource allocation challenges in social science, clinical, epidemiological, health service and population health research. These challenges are compounded if few members of a target population know each other or regularly interact. This paper reports on the sampling methods adopted in ethnographic case study research with a 'hard-to-reach' population. Methods To identify and engage a small yet diverse sample of people who met an unusual set of criteria (i.e., pet owners who had been treating cats or dogs for diabetes), four sampling strategies were used. First, copies of a recruitment letter were posted in pet-friendly places. Second, information about the study was diffused throughout the study period via word of mouth. Third, the lead investigator personally sent the recruitment letter via email to a pet owner, who then circulated the information to others, and so on. Fourth, veterinarians were enlisted to refer people who had diabetic pets. The second, third and fourth strategies rely on social networks and represent forms of chain referral sampling. Results Chain referral sampling via email proved to be the most efficient and effective, yielding a small yet diverse group of respondents within one month, and at negligible cost. Conclusions The widespread popularity of electronic communication technologies offers new methodological opportunities for researchers seeking to recruit from hard-to-reach populations. PMID:20089187

Harnessing social networks along with consumer-driven electronic communication technologies to identify and engage members of 'hard-to-reach' populations: a methodological case report.

PubMed

Rock, Melanie J

2010-01-20

Sampling in the absence of accurate or comprehensive information routinely poses logistical, ethical, and resource allocation challenges in social science, clinical, epidemiological, health service and population health research. These challenges are compounded if few members of a target population know each other or regularly interact. This paper reports on the sampling methods adopted in ethnographic case study research with a 'hard-to-reach' population. To identify and engage a small yet diverse sample of people who met an unusual set of criteria (i.e., pet owners who had been treating cats or dogs for diabetes), four sampling strategies were used. First, copies of a recruitment letter were posted in pet-friendly places. Second, information about the study was diffused throughout the study period via word of mouth. Third, the lead investigator personally sent the recruitment letter via email to a pet owner, who then circulated the information to others, and so on. Fourth, veterinarians were enlisted to refer people who had diabetic pets. The second, third and fourth strategies rely on social networks and represent forms of chain referral sampling. Chain referral sampling via email proved to be the most efficient and effective, yielding a small yet diverse group of respondents within one month, and at negligible cost. The widespread popularity of electronic communication technologies offers new methodological opportunities for researchers seeking to recruit from hard-to-reach populations.

Do recruitment patterns of young men who have sex with men (YMSM) recruited through respondent-driven sampling (RDS) violate assumptions?

PubMed

Phillips, Gregory; Kuhns, Lisa M; Garofalo, Rob; Mustanski, Brian

2014-12-01

To generate unbiased estimates for data collected using respondent-driven sampling (RDS), a number of assumptions need to be met: individuals recruit randomly from their social network and people can accurately report their eligible network size. However, research has shown that these assumptions are often violated. This study used baseline data from Crew 450, a longitudinal study of young men who have sex with men in Chicago who were recruited via a modified form of RDS and its network substudy, in which a subset of 175 participants reported details on the composition and characteristics of their social network at either 1 or 2 years postbaseline. Nearly two-thirds of participants reported giving coupons to at least one alter (64%), and 56.3% believed their alter(s) used the coupons. Frequency of communication, closeness and type of relationship played a major role in determining coupon distribution. Participants whose alters used coupons were significantly less likely to describe the strength of their relationship as 'not at all close' (OR=0.08; 95% CI 0.02 to 0.36) compared with 'very close' and to communicate weekly (OR=0.20; 95% CI 0.08 to 0.49) or 1-6 times in the past 6 months (OR=0.18; 95% CI 0.06 to 0.59). Contrary to RDS assumptions, we found that relationship characteristics played a significant role when individuals decided to whom they would give coupons. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Improving gambling survey research using dual-frame sampling of landline and mobile phone numbers.

PubMed

Jackson, Alun C; Pennay, Darren; Dowling, Nicki A; Coles-Janess, Bernadette; Christensen, Darren R

2014-06-01

Gambling prevalence studies are typically conducted within a single (landline) telephone sampling frame. This practice continues, despite emerging evidence that significant differences exist between landline and mobile (cell) phone only households. This study utilised a dual-frame (landline and mobile) telephone sampling methodology to cast light on the extent of differences across groups of respondents in respect to demographic, health, and gambling characteristics. A total of 2,014 participants from across Australian states and territories ranging in age from 18 to 96 years participated. Interviews were conducted using computer assisted telephone interviewing technology where 1,012 respondents from the landline sampling frame and 1,002 from the mobile phone sampling frame completed a questionnaire about gambling and other health behaviours. Responses across the landline sampling frame, the mobile phone sampling frame, and the subset of the mobile phone sampling frame that possessed a mobile phone only (MPO) were contrasted. The findings revealed that although respondents in the landline sample (62.7 %) did not significantly differ from respondents in the mobile phone sample (59.2 %) in gambling participation in the previous 12 months, they were significantly more likely to have gambled in the previous 12 months than the MPO sample (56.4 %). There were no significant differences in internet gambling participation over the previous 12 months in the landline sample (4.7 %), mobile phone sample (4.7 %) and the MPO sample (5.0 %). However, endorsement of lifetime problem gambling on the NODS-CLiP was significantly higher within the mobile sample (10.7 %) and the MPO sample (14.8 %) than the landline sample (6.6 %). Our research supports previous findings that reliance on a traditional landline telephone sampling approach effectively excludes distinct subgroups of the population from being represented in research findings. Consequently, we suggest that research best practice necessitates the use of a dual-frame sampling methodology. Despite inherent logistical and cost issues, this approach needs to become the norm in gambling survey research.

A Tale of Two Cities: Stigma and Health Outcomes Among People with HIV who Inject Drugs in St. Petersburg, Russia and Kohtla-Järve, Estonia

PubMed Central

Burke, Sara E.; Calabrese, Sarah K.; Dovidio, John F.; Levina, Olga S.; Uusküla, Anneli; Niccolai, Linda M.; Abel-Ollo, Katri; Heimer, Robert

2015-01-01

Experiences of stigma are often associated with negative mental and physical health outcomes. The present work tested the associations between stigma and health-related outcomes among people with HIV who inject drugs in Kohtla-Järve, Estonia and St. Petersburg, Russia. These two cities share some of the highest rates of HIV outside of sub-Saharan Africa, largely driven by injection drug use, but Estonia has implemented harm reduction services more comprehensively. People who inject drugs were recruited using respondent-driven sampling; those who indicated being HIV-positive were included in the present sample (n=381 in St. Petersburg; n=288 in Kohtla-Järve). Participants reported their health information and completed measures of internalized HIV stigma, anticipated HIV stigma, internalized drug stigma, and anticipated drug stigma. Participants in both locations indicated similarly high levels of all four forms of stigma. However, stigma variables were more strongly associated with health outcomes in Russia than in Estonia. The St. Petersburg results were consistent with prior work linking stigma and health. Lower barriers to care in Kohtla-Järve may help explain why social stigma was not closely tied to negative health outcomes there. Implications for interventions and health policy are discussed. PMID:25703668

Mental health literacy, stigma and perception of causation of mental illness among Chinese people in Taiwan.

PubMed

Zhuang, Xiao Yu; Wong, Daniel Fu Keung; Cheng, Chi-Wei; Pan, Shu-Man

2017-09-01

Few studies have been performed to explore mental health literacy and stigmatising attitudes towards mental illness and their relationships with causal beliefs about mental illness among Chinese people in Taiwan. Using a comparative approach, this study attempted to compare the mental health literacy and stigmatising attitudes of Taiwanese Chinese with those found among Australian and Japanese participants in other studies and to explore how mental health literacy and stigmatising attitudes relate to different perceptions of causes of mental illness. A convenience sample of 287 participants completed a battery of standardised questionnaires. A much lower percentage of Taiwanese people than Australians could correctly identify depression and schizophrenia. The Taiwanese respondents rated psychiatrists and clinical psychologists as more helpful than social workers and general practitioners (GPs) and expressed more uncertainty about the usefulness of certain medications when compared to the Australian and Japanese samples. Interestingly, Taiwanese Chinese hold similarly high levels of stigma towards schizophrenia, but lower levels of stigma towards depression when compared to the Japanese respondents. Taiwanese respondents who have higher levels of mental health literacy about schizophrenia were less willing to interact with people with schizophrenia than those with lower levels of mental health literacy. This study underlines the need for public education programmes to improve knowledge of various mental illnesses and to reduce stigmatising attitudes among Taiwanese Chinese. The aforementioned socially and culturally driven beliefs must be taken into consideration so that culturally relevant education programmes can be developed.

Surveying alcohol and other drug use through telephone sampling: a comparison of landline and mobile phone samples.

PubMed

Livingston, Michael; Dietze, Paul; Ferris, Jason; Pennay, Darren; Hayes, Linda; Lenton, Simon

2013-03-16

Telephone surveys based on samples of landline telephone numbers are widely used to measure the prevalence of health risk behaviours such as smoking, drug use and alcohol consumption. An increasing number of households are relying solely on mobile telephones, creating a potential bias for population estimates derived from landline-based sampling frames which do not incorporate mobile phone numbers. Studies in the US have identified significant differences between landline and mobile telephone users in smoking and alcohol consumption, but there has been little work in other settings or focussed on illicit drugs. This study examined Australian prevalence estimates of cannabis use, tobacco smoking and risky alcohol consumption based on samples selected using a dual-frame (mobile and landline) approach. Respondents from the landline sample were compared both to the overall mobile sample (including respondents who had access to a landline) and specifically to respondents who lived in mobile-only households. Bivariate comparisons were complemented with multivariate logistic regression models, controlling for the effects of basic demographic variables. The landline sample reported much lower prevalence of tobacco use, cannabis use and alcohol consumption than the mobile samples. Once demographic variables were adjusted for, there were no significant differences between the landline and mobile respondents on any of the alcohol measures examined. In contrast, the mobile samples had significantly higher rates of cannabis and tobacco use, even after adjustment. Weighted estimates from the dual-frame sample were generally higher than the landline sample across all substances, but only significantly higher for tobacco use. Landline telephone surveys in Australia are likely to substantially underestimate the prevalence of tobacco smoking by excluding potential respondents who live in mobile-only households. In contrast, estimates of alcohol consumption and cannabis use from landline surveys are likely to be broadly accurate, once basic demographic weighting is undertaken.

User-Driven Sampling Strategies in Image Exploitation

DOE PAGES

Harvey, Neal R.; Porter, Reid B.

2013-12-23

Visual analytics and interactive machine learning both try to leverage the complementary strengths of humans and machines to solve complex data exploitation tasks. These fields overlap most significantly when training is involved: the visualization or machine learning tool improves over time by exploiting observations of the human-computer interaction. This paper focuses on one aspect of the human-computer interaction that we call user-driven sampling strategies. Unlike relevance feedback and active learning sampling strategies, where the computer selects which data to label at each iteration, we investigate situations where the user selects which data is to be labeled at each iteration. User-drivenmore » sampling strategies can emerge in many visual analytics applications but they have not been fully developed in machine learning. We discovered that in user-driven sampling strategies suggest new theoretical and practical research questions for both visualization science and machine learning. In this paper we identify and quantify the potential benefits of these strategies in a practical image analysis application. We find user-driven sampling strategies can sometimes provide significant performance gains by steering tools towards local minima that have lower error than tools trained with all of the data. Furthermore, in preliminary experiments we find these performance gains are particularly pronounced when the user is experienced with the tool and application domain.« less

Passive injection control for microfluidic systems

DOEpatents

Paul, Phillip H.; Arnold, Don W.; Neyer, David W.

2004-12-21

Apparatus for eliminating siphoning, "dead" regions, and fluid concentration gradients in microscale analytical devices. In its most basic embodiment, the present invention affords passive injection control for both electric field-driven and pressure-driven systems by providing additional fluid flow channels or auxiliary channels disposed on either side of a sample separation column. The auxiliary channels are sized such that volumetric fluid flow rate through these channels, while sufficient to move the sample away from the sample injection region in a timely fashion, is less than that through the sample separation channel or chromatograph.

High heterogeneity of HIV-related sexual risk among transgender people in Ontario, Canada: a province-wide respondent-driven sampling survey.

PubMed

Bauer, Greta R; Travers, Robb; Scanlon, Kyle; Coleman, Todd A

2012-04-20

Studies of HIV-related risk in trans (transgender, transsexual, or transitioned) people have most often involved urban convenience samples of those on the male-to-female (MTF) spectrum. Studies have detected high prevalences of HIV-related risk behaviours, self-reported HIV, and HIV seropositivity. The Trans PULSE Project conducted a multi-mode survey using respondent-driven sampling to recruit 433 trans people in Ontario, Canada. Weighted estimates were calculated for HIV-related risk behaviours, HIV testing and self-reported HIV, including subgroup estimates for gender spectrum and ethno-racial groups. Trans people in Ontario report a wide range of sexual behaviours with a full range of partner types. High proportions - 25% of female-to-male (FTM) and 51% of MTF individuals - had not had a sex partner within the past year. Of MTFs, 19% had a past-year high-risk sexual experience, versus 7% of FTMs. The largest behavioural contributors to HIV risk were sexual behaviours some may assume trans people do not engage in: unprotected receptive genital sex for FTMs and insertive genital sex for MTFs. Overall, 46% had never been tested for HIV; lifetime testing was highest in Aboriginal trans people and lowest among non-Aboriginal racialized people. Approximately 15% of both FTM and MTF participants had engaged in sex work or exchange sex and about 2% currently work in the sex trade. Self-report of HIV prevalence was 10 times the estimated baseline prevalence for Ontario. However, given wide confidence intervals and the high proportion of trans people who had never been tested for HIV, estimating the actual prevalence was not possible. Results suggest potentially higher than baseline levels of HIV; however low testing rates were observed and self-reported prevalences likely underestimate seroprevalence. Explicit inclusion of trans people in epidemiological surveillance statistics would provide much-needed information on incidence and prevalence. Given the wide range of sexual behaviours and partner types reported, HIV prevention programs and materials should not make assumptions regarding types of behaviours trans people do or do not engage in.

Changes in Family Cohesion and Acculturative Stress among Recent Latino Immigrants

PubMed Central

IBAÑEZ, GLADYS E.; DILLON, FRANK; SANCHEZ, MARIANA; DE LA ROSA, MARIO; LI, TAN; VILLAR, MARIA ELENA

2016-01-01

Family relationships can serve as an important source of support during the acculturation process; yet, how the stress related to acculturation, or acculturative stress, may impact family functioning across time is not clear. Participants (n = 479), between the ages of 18-34 were recruited using respondent driven sampling methodology. Findings suggest family cohesion decreased over time; however, it decreased less for those reporting more acculturative stress. The implication is that for those Latino immigrants who struggle to adapt to their new host culture, family remains a source of support more so than for those who do not struggle as much. PMID:27087789

Convenience Samples and Caregiving Research: How Generalizable Are the Findings?

ERIC Educational Resources Information Center

Pruchno, Rachel A.; Brill, Jonathan E.; Shands, Yvonne; Gordon, Judith R.; Genderson, Maureen Wilson; Rose, Miriam; Cartwright, Francine

2008-01-01

Purpose: We contrast characteristics of respondents recruited using convenience strategies with those of respondents recruited by random digit dial (RDD) methods. We compare sample variances, means, and interrelationships among variables generated from the convenience and RDD samples. Design and Methods: Women aged 50 to 64 who work full time and…

Self-Regulation of Behavior: Students versus Other Adults

ERIC Educational Resources Information Center

Jakesova, Jitka; Gavora, Peter; Kalenda, Jan

2016-01-01

The objective of this research is to compare self-regulation of behaviour of two Czech samples. The first one was the representative sample of Czech adults that consisted of 1060 respondents. The second sample was university students and consisted of 1244 respondents. The measuring tool was an adapted Self-Regulation Questionnaire of which two…

Reasons for non-attendance to cervical screening and preferences for HPV self-sampling in Dutch women.

PubMed

Bosgraaf, Remko P; Ketelaars, Pleun J W; Verhoef, Viola M J; Massuger, Leon F A G; Meijer, Chris J L M; Melchers, Willem J G; Bekkers, Ruud L M

2014-07-01

High attendance rates in cervical screening are essential for effective cancer prevention. Offering HPV self-sampling to non-responders increases participation rates. The objectives of this study were to determine why non-responders do not attend regular screening, and why they do or do not participate when offered a self-sampling device. A questionnaire study was conducted in the Netherlands from October 2011 to December 2012. A total of 35,477 non-responders were invited to participate in an HPV self-sampling study; 5347 women did opt out. Finally, 30,130 women received a questionnaire and self-sampling device. The analysis was based on 9484 returned questionnaires (31.5%) with a self-sample specimen, and 682 (2.3%) without. Among women who returned both, the main reason for non-attendance to cervical screening was that they forgot to schedule an appointment (3068; 32.3%). The most important reason to use the self-sampling device was the opportunity to take a sample in their own time-setting (4763; 50.2%). A total of 30.9% of the women who did not use the self-sampling device preferred after all to have a cervical smear taken instead. Organisational barriers are the main reason for non-attendance in regular cervical screening. Important reasons for non-responders to the regular screening to use a self-sampling device are convenience and self-control. Copyright © 2014 Elsevier Inc. All rights reserved.

Statistical power and optimal design in experiments in which samples of participants respond to samples of stimuli.

PubMed

Westfall, Jacob; Kenny, David A; Judd, Charles M

2014-10-01

Researchers designing experiments in which a sample of participants responds to a sample of stimuli are faced with difficult questions about optimal study design. The conventional procedures of statistical power analysis fail to provide appropriate answers to these questions because they are based on statistical models in which stimuli are not assumed to be a source of random variation in the data, models that are inappropriate for experiments involving crossed random factors of participants and stimuli. In this article, we present new methods of power analysis for designs with crossed random factors, and we give detailed, practical guidance to psychology researchers planning experiments in which a sample of participants responds to a sample of stimuli. We extensively examine 5 commonly used experimental designs, describe how to estimate statistical power in each, and provide power analysis results based on a reasonable set of default parameter values. We then develop general conclusions and formulate rules of thumb concerning the optimal design of experiments in which a sample of participants responds to a sample of stimuli. We show that in crossed designs, statistical power typically does not approach unity as the number of participants goes to infinity but instead approaches a maximum attainable power value that is possibly small, depending on the stimulus sample. We also consider the statistical merits of designs involving multiple stimulus blocks. Finally, we provide a simple and flexible Web-based power application to aid researchers in planning studies with samples of stimuli.

Do insulin cartridges really provide a lower risk of potential diabetes complications than traditional vials?

PubMed Central

Al-Sharayri, Mohammad G.; Aljbori, Tariq M.; Migdadi, Qusai M.; Al-Omoush, Marwa B.; Jaarah, Ayman R.

2013-01-01

Scope Recently, many publicly funded healthcare organizations suffered from an economical crisis. This forced some organizations to utilize less costly alternatives where possible. Insulin cartridges and vials are examples. Many patients are questioning the difference between the two alternatives as they contain the same active ingredient. Objective To find out if insulin cartridges really provide a lower risk of potential diabetes complications than traditional vials. Method A questionnaire was used to ask two random samples of diabetic patients about the development of some diabetes complications. The first sample (n = 41) consisted of patients using cartridges; the second sample (n = 40) consisted of patients using vials. Patients were randomly selected from the endocrine clinic and the out-patient pharmacy in Al-Hussein Hospital in King Hussein Medical Center in Amman- Jordan. Results 44% of respondents in the first sample did not suffer from any complication; on the other hand, the percentage was only 15% of respondents in the second sample. All respondents (100%) in the first sample suffered from only 2 complications or less; however, 25% of the respondents in the second sample suffered from 3 or more complications. Nephropathy complications, were slightly higher in the first sample; 22% compared to 15% in the second sample. On the other hand, all complications reported in the second sample were higher; 30% for neuropathy, 65% for retinopathy complications and 42.5% for extremities damage compared to only 9.7%, 7.3% and 26.8% respectively in the first sample. Conclusion In general, respondents who were using cartridges reported a lesser incidence of diabetes complications. Although many organizations suffered from an economical crisis, the cost-effectiveness aspect should be taken into consideration when purchasing medical alternatives. This will provide higher quality of life for patients and eventually lower hidden and future costs for the organizations. PMID:25161382

Do insulin cartridges really provide a lower risk of potential diabetes complications than traditional vials?

PubMed

Al-Sharayri, Mohammad G; Aljbori, Tariq M; Migdadi, Qusai M; Al-Omoush, Marwa B; Jaarah, Ayman R

2014-09-01

Recently, many publicly funded healthcare organizations suffered from an economical crisis. This forced some organizations to utilize less costly alternatives where possible. Insulin cartridges and vials are examples. Many patients are questioning the difference between the two alternatives as they contain the same active ingredient. To find out if insulin cartridges really provide a lower risk of potential diabetes complications than traditional vials. A questionnaire was used to ask two random samples of diabetic patients about the development of some diabetes complications. The first sample (n = 41) consisted of patients using cartridges; the second sample (n = 40) consisted of patients using vials. Patients were randomly selected from the endocrine clinic and the out-patient pharmacy in Al-Hussein Hospital in King Hussein Medical Center in Amman- Jordan. 44% of respondents in the first sample did not suffer from any complication; on the other hand, the percentage was only 15% of respondents in the second sample. All respondents (100%) in the first sample suffered from only 2 complications or less; however, 25% of the respondents in the second sample suffered from 3 or more complications. Nephropathy complications, were slightly higher in the first sample; 22% compared to 15% in the second sample. On the other hand, all complications reported in the second sample were higher; 30% for neuropathy, 65% for retinopathy complications and 42.5% for extremities damage compared to only 9.7%, 7.3% and 26.8% respectively in the first sample. In general, respondents who were using cartridges reported a lesser incidence of diabetes complications. Although many organizations suffered from an economical crisis, the cost-effectiveness aspect should be taken into consideration when purchasing medical alternatives. This will provide higher quality of life for patients and eventually lower hidden and future costs for the organizations.

How to find future ecstasy-users: targeted and snowball sampling in an ethically sensitive context.

PubMed

Vervaeke, Hylke K E; Korf, Dirk J; Benschop, Annemieke; van den Brink, Wim

2007-08-01

This article documents the design and the sampling procedures of a prospective longitudinal multidisciplinary study on the neurotoxicity of ecstasy (MDMA): the Netherlands XTC Toxicity Study (NeXT). Targeted and snowball sampling was used to recruit 188 respondents who were ecstasy-naive at baseline. All respondents completed baseline questionnaires and underwent medical and neuropsychological examinations. At the end of a 11- to 26- month follow-up period in which they completed four additional questionnaires, 160 respondents remained (85.1%). A total of 65 participants (40.6%) took ecstasy for the first time during the follow-up period. This paper discusses the ethical dilemmas inherent in a study of this type and the specific problems and solutions that emerged in the sampling. The sampling was tightly constrained by our need to locate respondents who were potential future ecstasy users while also meeting strict medical and technical criteria. The 'intention to use' criterion proved to be a clear-cut inclusion rule that was practical to apply in the fieldwork.

A more rational, theory-driven approach to analysing the factor structure of the Edinburgh Postnatal Depression Scale.

PubMed

Kozinszky, Zoltan; Töreki, Annamária; Hompoth, Emőke A; Dudas, Robert B; Németh, Gábor

2017-04-01

We endeavoured to analyze the factor structure of the Edinburgh Postnatal Depression Scale (EPDS) during a screening programme in Hungary, using exploratory (EFA) and confirmatory factor analysis (CFA), testing both previously published models and newly developed theory-driven ones, after a critical analysis of the literature. Between April 2011 and January 2015, a sample of 2967 pregnant women (between 12th and 30th weeks of gestation) and 714 women 6 weeks after delivery completed the Hungarian version of the EPDS in South-East Hungary. EFAs suggested unidimensionality in both samples. 33 out of 42 previously published models showed good and 6 acceptable fit with our antepartum data in CFAs, whilst 10 of them showed good and 28 acceptable fit in our postpartum sample. Using multiple fit indices, our theory-driven anhedonia (items 1,2) - anxiety (items 4,5) - low mood (items 8,9) model provided the best fit in the antepartum sample. In the postpartum sample, our theory-driven models were again among the best performing models, including an anhedonia and an anxiety factor together with either a low mood or a suicidal risk factor (items 3,6,10). The EPDS showed moderate within- and between-culture invariability, although this would also need to be re-examined with a theory-driven approach. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

Sources of Pharmaceutical Opioids for Non-Medical Use Among Young Adults

PubMed Central

Daniulaityte, Raminta; Falck, Russel; Carlson, Robert G.

2014-01-01

The study uses qualitative and quantitative data to describe sources of pain pills for illicit use among young adult (18–23 year-old) users. Respondent driven sampling was used to recruit 390 individuals in the Columbus, Ohio area. The sample was almost 50% white and about 55% male. Qualitative interview participants (n=45) were selected from the larger sample. Qualitative data suggest that pharmaceutical opioid availability was so pervasive that most individuals did not have to venture outside of their immediate social networks to find people who sold or shared pills. Participants emphasized differences between those who are actively involved in obtaining pills, and those who play a more passive role. Active involvement was described as going out searching for pills and paying money to obtain them. In contrast, passive role included obtaining pills when somebody offered or shared them free of charge. Multiple logistic regression analysis indicates that a more active role in obtaining pharmaceutical opioids was related to being white, more frequent use of pharmaceutical opioids, extended-release oxycodone use, and using pharmaceutical opioids to get high, as opposed to self-treating a health problem. The study results can help inform drug use epidemiology, interventions and policy. PMID:25052878

A Comparison of Match-to-Sample and Respondent-Type Training of Equivalence Classes

ERIC Educational Resources Information Center

Clayton, Michael C.; Hayes, Linda J.

2004-01-01

Throughout the 25-year history of research on stimulus equivalence, one feature of the training procedure has remained constant, namely, the requirement of operant responding during the training procedures. The present investigation compared the traditional match-to-sample (MTS) training with a more recent respondent-type (ReT) procedure. Another…

Using Network Sampling and Recruitment Data to Understand Social Structures Related to Community Health in a Population of People Who Inject Drugs in Rural Puerto Rico.

PubMed

Coronado-García, Mayra; Thrash, Courtney R; Welch-Lazoritz, Melissa; Gauthier, Robin; Reyes, Juan Carlos; Khan, Bilal; Dombrowski, Kirk

2017-06-01

This research examined the social network and recruitment patterns of a sample of people who inject drugs (PWIDs) in rural Puerto Rico, in an attempt to uncover systematic clustering and between-group social boundaries that potentially influence disease spread. Respondent driven sampling was utilized to obtain a sample of PWID in rural Puerto Rico. Through eight initial "seeds", 317 injection drug users were recruited. Using recruitment patterns of this sample, estimates of homophily and affiliation were calculated using RDSAT. Analyses showed clustering within the social network of PWID in rural Puerto Rico. In particular, females showed a very high tendency to recruit male PWID, which suggests low social cohesion among female PWID. Results for (believed) HCV status at the time of interview indicate that HCV+ individuals were less likely to interact with HCV- individuals or those who were unaware of their status, and may be acting as "gatekeepers" to prevent disease spread. Individuals who participated in a substance use program were more likely to affiliate with one another. The use of speedballs was related to clustering within the network, in which individuals who injected this mixture were more likely to affiliate with other speedball users. Social clustering based on several characteristics and behaviors were found within the IDU population in rural Puerto Rico. RDS was effective in not only garnering a sample of PWID in rural Puerto Rico, but also in uncovering social clustering that can potentially influence disease spread among this population.

Sexual violence and sub-Saharan migrants in Morocco: a community-based participatory assessment using respondent driven sampling.

PubMed

Keygnaert, Ines; Dialmy, Abdessamad; Manço, Altay; Keygnaert, Jeroen; Vettenburg, Nicole; Roelens, Kristien; Temmerman, Marleen

2014-05-08

The European Union contracted Morocco to regulate migration from so-called “transit migrants” from Morocco to Europe via the European Neighbourhood Policy. Yet, international organisations signal that human, asylum and refugee rights are not upheld in Morocco and that many sub-Saharan migrants suffer from ill-health and violence. Hence, our study aimed at 1) investigating the nature of violence that sub-Saharan migrants experience around and in Morocco, 2) assessing which determinants they perceive as decisive and 3) formulating prevention recommendations. Applying Community-Based Participatory Research, we trained twelve sub-Saharan migrants as Community Researchers to conduct in-depth interviews with peers, using Respondent Driven Sampling. We used Nvivo 8 to analyse the data. We interpreted results with Community Researchers and the Community Advisory Board and commonly formulated prevention recommendations. Among the 154 (60 F-94 M) sub-Saharan migrants interviewed, 90% reported cases of multiple victimizations, 45% of which was sexual, predominantly gang rape. Seventy-nine respondents were personally victimized, 41 were forced to witness how relatives or co-migrants were victimized and 18 others knew of peer victimisation. Severe long lasting ill-health consequences were reported while sub-Saharan victims are not granted access to the official health care system. Perpetrators were mostly Moroccan or Algerian officials and sub-Saharan gang leaders who function as unofficial yet rigorous migration professionals at migration ‘hubs’. They seem to proceed in impunity. Respondents link risk factors mainly to their undocumented and unprotected status and suggest that migrant communities set-up awareness raising campaigns on risks while legal and policy changes enforcing human rights, legal protection and human treatment of migrants along with severe punishment of perpetrators are politically lobbied for. Sub-Saharan migrants are at high risk of sexual victimization and subsequent ill-health in and around Morocco. Comprehensive cross-border and multi-level prevention actions are urgently called for. Given the European Neighbourhood Policy, we deem it paramount that the European Union politically cares for these migrants’ lives and health, takes up its responsibility, drastically changes migration regulation into one that upholds human rights beyond survival and enforces all authorities involved to restore migrants’ lives worthy to be lived again.

Sexual violence and sub-Saharan migrants in Morocco: a community-based participatory assessment using respondent driven sampling

PubMed Central

2014-01-01

Background The European Union contracted Morocco to regulate migration from so-called “transit migrants” from Morocco to Europe via the European Neighbourhood Policy. Yet, international organisations signal that human, asylum and refugee rights are not upheld in Morocco and that many sub-Saharan migrants suffer from ill-health and violence. Hence, our study aimed at 1) investigating the nature of violence that sub-Saharan migrants experience around and in Morocco, 2) assessing which determinants they perceive as decisive and 3) formulating prevention recommendations. Methods Applying Community-Based Participatory Research, we trained twelve sub-Saharan migrants as Community Researchers to conduct in-depth interviews with peers, using Respondent Driven Sampling. We used Nvivo 8 to analyse the data. We interpreted results with Community Researchers and the Community Advisory Board and commonly formulated prevention recommendations. Results Among the 154 (60 F-94 M) sub-Saharan migrants interviewed, 90% reported cases of multiple victimizations, 45% of which was sexual, predominantly gang rape. Seventy-nine respondents were personally victimized, 41 were forced to witness how relatives or co-migrants were victimized and 18 others knew of peer victimisation. Severe long lasting ill-health consequences were reported while sub-Saharan victims are not granted access to the official health care system. Perpetrators were mostly Moroccan or Algerian officials and sub-Saharan gang leaders who function as unofficial yet rigorous migration professionals at migration ‘hubs’. They seem to proceed in impunity. Respondents link risk factors mainly to their undocumented and unprotected status and suggest that migrant communities set-up awareness raising campaigns on risks while legal and policy changes enforcing human rights, legal protection and human treatment of migrants along with severe punishment of perpetrators are politically lobbied for. Conclusion Sub-Saharan migrants are at high risk of sexual victimization and subsequent ill-health in and around Morocco. Comprehensive cross-border and multi-level prevention actions are urgently called for. Given the European Neighbourhood Policy, we deem it paramount that the European Union politically cares for these migrants’ lives and health, takes up its responsibility, drastically changes migration regulation into one that upholds human rights beyond survival and enforces all authorities involved to restore migrants’ lives worthy to be lived again. PMID:24885537

End-of-Life Preferences: A Theory-Driven Inventory

ERIC Educational Resources Information Center

Bonin-Scaon, Sylvie; Munoz Sastre, Maria Teresa; Chasseigne, Gerard; Sorum, Paul C.; Mullet, Etienne

2009-01-01

The study aimed at making a theory-driven inventory of end-of-life preferences. Participants were asked about a variety of preferences representing all eight motivational states described in Apter's Metamotivational Theory (AMT; Apter, 2001). Data from a convenience sample of 965 community participants and a convenience sample of 81 persons…

BIOHAZ: Rapid On-Site Biological Detection for First Responders

DTIC Science & Technology

2001-09-01

numbers comprise the compilation report: ADP013371 thru ADP013468 UNCLASSIFIED 84. BIORAZ: Rapid On- Site Biological Detection for First Responders Randall... responders an integated capability to collect an environmental sample and to rapidly screen that sample on site for the presence of biological material. This...further analyzed on site with immunoassay tickets before being sent to a laboratory. This system provides the emergency responders with a capability that

Studying Psychosocial Barriers to Drug Treatment Among Chinese Methamphetamine Users Using A 3-Step Latent Class Analysis.

PubMed

Wang, Jichuan; Kelly, Brian C; Liu, Tieqiao; Hao, Wei

2016-03-01

Given the growth in methamphetamine use in China during the 21st century, we assessed perceived psychosocial barriers to drug treatment among this population. Using a sample of 303 methamphetamine users recruited via Respondent Driven Sampling, we use Latent Class Analysis (LCA) to identify possible distinct latent groups among Chinese methamphetamine users on the basis of their perceptions of psychosocial barriers to drug treatment. After covariates were included to predict latent class membership, the 3-step modeling approach was applied. Our findings indicate that the Chinese methamphetamine using population was heterogeneous on perceptions of drug treatment barriers; four distinct latent classes (subpopulations) were identified--Unsupported Deniers, Deniers, Privacy Anxious, and Low Barriers--and individual characteristics shaped the probability of class membership. Efforts to link Chinese methamphetamine users to treatment may require a multi-faceted approach that attends to differing perceptions about impediments to drug treatment. Copyright © 2015. Published by Elsevier Inc.

Vulnerability to sexually transmitted infections in women who sell sex on the route of prostitution and sex tourism in central Brazil.

PubMed

de Matos, Marcos André de; Caetano, Karlla Antonieta Amorim; França, Divânia Dias da Silva; Pinheiro, Raquel Silva; de Moraes, Luciene Carneiro; Teles, Sheila Araujo

2013-01-01

to investigate knowledge on sexually transmitted diseases (STDs), STD-related risk behaviors, and signs/symptoms of STDs among female sex workers (FSWs). a cross-sectional study was conducted with a probabilistic sample comprising 395 women recruited using a respondent-driven sampling method between 2009 and 2010. The data were collected during face-to-face interviews. most of the participants were young adults, had a low educational level, and had poor knowledge on the transmission paths of the human immunodeficiency virus (HIV). Over one-third of the participants were not able to describe the signs/symptoms of STDs. The prevalence rates of vaginal discharge and wounds/ulcers were 49.0% and 8.6%, respectively, but 41.7% of the women had not sought treatment. the results indicate the need for public health policies focusing on the control and prevention of STDs in this population, especially for the FSWs who are active in an important prostitution and sex tourism route in central Brazil.

Disgust and Obsessive Beliefs in Contamination-related OCD

PubMed Central

Cisler, Josh M.; Brady, Robert E.; Olatunji, Bunmi O.; Lohr, Jeffrey M.

2010-01-01

A large body of evidence suggests that disgust is an important affective process underlying contamination fear. An independent line of research demonstrates that obsessive beliefs, particularly overestimations of threat, are also an important cognitive process underlying contamination fear. The present study attempts to integrate these two lines of research by testing whether obsessive beliefs potentiate the influence of disgust propensity on contamination fear. The interaction between disgust propensity and obsessive beliefs was tested in two large non-clinical samples (N = 252 in Study 1; N = 308 in Study 2) using two different self-report measures of contamination fear. Regression analyses supported the hypotheses in both samples. The interaction remained significant when controlling for negative affect. The results are hypothesized to suggest that contamination fear results, at least partly, from obsessive beliefs about the contamination-based appraisals that accompany heightened disgust responding. These results complement previous affective-driven explanations of the role of disgust in contamination fear by suggesting cognitive factors that similarly potentiate disgust’s role in contamination fear. PMID:20877585

Social Network Characteristics and HIV Vulnerability Among Transgender Persons in San Salvador: Identifying Opportunities for HIV Prevention Strategies

PubMed Central

Barrington, Clare; Wejnert, Cyprian; Guardado, Maria Elena; Nieto, Ana Isabel; Bailey, Gabriela Paz

2013-01-01

The purpose of this study is to improve understanding of HIV vulnerability and opportunities for HIV prevention within the social networks of male-to-female transgender persons in San Salvador, El Salvador. We compare HIV prevalence and behavioral data from a sample of gay-identified men who have sex with men (MSM) (n = 279), heterosexual or bisexual identified MSM (n = 229) and transgender persons (n = 67) recruited using Respondent Driven Sampling. Transgender persons consistently reported higher rates of HIV risk behavior than the rest of the study population and were significantly more likely to be involved in sex work. While transgender persons reported the highest rates of exposure to HIV educational activities they had the lowest levels of HIV-related knowledge. Transgender respondents’ social networks were homophilous and efficient at recruiting other transgender persons. Findings suggest that transgender social networks could provide an effective and culturally relevant opportunity for HIV prevention efforts in this vulnerable population. PMID:21538082

Prevalence of internalized homophobia and HIV associated risks among men who have sex with men in Nigeria.

PubMed

Adebajo, Sylvia B; Eluwa, George I; Allman, Dan; Myers, Ted; Ahonsi, Babatunde A

2012-12-01

This study assessed the level of internalized homophobia and associated factors among men who have sex with men (MSM) in Nigeria. Using respondent driven sampling, MSM were recruited in Lagos and Ibadan between July and September, 2006. Internalized homophobia was assessed as a negative composite score using an 11-item scale. A total of 1,125 MSM were interviewed. About 44.4% self-identified as homosexual or gay while 55% regarded themselves as bisexual. About a third of the respondents reported internalized homophobia. With homosexual/gay men as reference, respondents who self-identified as bisexual were two times more likely [AOR 2.1; 95 CI: 1.6 - 2.9, p < 0.001] to report internalized homophobia. Those who were HIV positive were also twice as likely to report internalized homophobia compared to those who were HIV negative [AOR 1.8; 95% CI: 1.2 - 2.7, p = 0.004]. As internalized homophobia impedes acceptance of HIV prevention programming, identifying MSM who experience internalized homophobia is integral to the success of HIV prevention programming in Nigeria.

Survey of 1975-76 Physics and Astronomy Bachelor's Degree Recipients. AIP Report.

ERIC Educational Resources Information Center

Ellis, Susanne D.

This report presents data from a survey of 1975-76 physics and astronomy bachelor degree recipients. From a sample of 3,969 physics graduates, 2,616 responded. From a sample of 180 astronomy graduates, 110 responded. Data on the 1975-76 sample are presented in tabular form, and comparisons are made with responses to previous studies for several…

Comparison of Contact Patterns Relevant for Transmission of Respiratory Pathogens in Thailand and the Netherlands Using Respondent-Driven Sampling

PubMed Central

Stein, Mart L.; van Steenbergen, Jim E.; Buskens, Vincent; van der Heijden, Peter G. M.; Chanyasanha, Charnchudhi; Tipayamongkholgul, Mathuros; Thorson, Anna E.; Bengtsson, Linus; Lu, Xin; Kretzschmar, Mirjam E. E.

2014-01-01

Understanding infection dynamics of respiratory diseases requires the identification and quantification of behavioural, social and environmental factors that permit the transmission of these infections between humans. Little empirical information is available about contact patterns within real-world social networks, let alone on differences in these contact networks between populations that differ considerably on a socio-cultural level. Here we compared contact network data that were collected in the Netherlands and Thailand using a similar online respondent-driven method. By asking participants to recruit contact persons we studied network links relevant for the transmission of respiratory infections. We studied correlations between recruiter and recruited contacts to investigate mixing patterns in the observed social network components. In both countries, mixing patterns were assortative by demographic variables and random by total numbers of contacts. However, in Thailand participants reported overall more contacts which resulted in higher effective contact rates. Our findings provide new insights on numbers of contacts and mixing patterns in two different populations. These data could be used to improve parameterisation of mathematical models used to design control strategies. Although the spread of infections through populations depends on more factors, found similarities suggest that spread may be similar in the Netherlands and Thailand. PMID:25423343

Approaches to Recruiting ‘Hard-To-Reach’ Populations into Re­search: A Review of the Literature

PubMed Central

Shaghaghi, Abdolreza; Bhopal, Raj S; Sheikh, Aziz

2011-01-01

Background: ‘Hard-to-reach’ is a term used to describe those sub-groups of the population that may be difficult to reach or involve in research or public health programmes. Application of a single term to call these sub-sections of populations implies a homogeneity within distinct groups, which does not necessarily exist. Different sampling techniques were introduced so far to recruit hard-to-reach populations. In this article, we have reviewed a range of ap­proaches that have been used to widen participation in studies. Methods: We performed a Pubmed and Google search for relevant English language articles using the keywords and phrases: (hard-to-reach AND population* OR sampl*), (hidden AND population* OR sample*) and (“hard to reach” AND population* OR sample*) and a consul­tation of the retrieved articles’ bibliographies to extract empirical evidence from publications that discussed or examined the use of sampling techniques to recruit hidden or hard-to-reach populations in health studies. Results: Reviewing the literature has identified a range of techniques to recruit hard-to-reach populations, including snowball sampling, respondent-driven sampling (RDS), indigenous field worker sampling (IFWS), facility-based sampling (FBS), targeted sampling (TS), time-location (space) sampling (TLS), conventional cluster sampling (CCS) and capture re-capture sampling (CR). Conclusion: The degree of compliance with a study by a certain ‘hard-to-reach’ group de­pends on the characteristics of that group, recruitment technique used and the subject of inter­est. Irrespective of potential advantages or limitations of the recruitment techniques reviewed, their successful use depends mainly upon our knowledge about specific characteristics of the target populations. Thus in line with attempts to expand the current boundaries of our know­ledge about recruitment techniques in health studies and their applications in varying situa­tions, we should also focus on possibly all contributing factors which may have an impact on participation rate within a defined population group. PMID:24688904

American Thoracic Society Member Survey on Climate Change and Health

PubMed Central

Bloodhart, Brittany; Ewart, Gary; Thurston, George D.; Balmes, John R.; Guidotti, Tee L.; Maibach, Edward W.

2015-01-01

The American Thoracic Society (ATS), in collaboration with George Mason University, surveyed a random sample of ATS members to assess their perceptions of, clinical experiences with, and preferred policy responses to climate change. An e-mail containing an invitation from the ATS President and a link to an online survey was sent to 5,500 randomly selected U.S. members; up to four reminder e-mails were sent to nonrespondents. Responses were received from members in 49 states and the District of Columbia (n = 915); the response rate was 17%. Geographic distribution of respondents mirrored that of the sample. Survey estimates’ confidence intervals were ±3.5% or smaller. Results indicate that a large majority of ATS members have concluded that climate change is happening (89%), that it is driven by human activity (68%), and that it is relevant to patient care (“a great deal”/“a moderate amount”) (65%). A majority of respondents indicated they were already observing health impacts of climate change among their patients, most commonly as increases in chronic disease severity from air pollution (77%), allergic symptoms from exposure to plants or mold (58%), and severe weather injuries (57%). A larger majority anticipated seeing these climate-related health impacts in the next 2 decades. Respondents indicated that physicians and physician organizations should play an active role in educating patients, the public, and policy makers on the human health effects of climate change. Overall, ATS members are observing that human health is already adversely affected by climate change and support responses to address this situation. PMID:25535822

American Thoracic Society member survey on climate change and health.

PubMed

Sarfaty, Mona; Bloodhart, Brittany; Ewart, Gary; Thurston, George D; Balmes, John R; Guidotti, Tee L; Maibach, Edward W

2015-02-01

The American Thoracic Society (ATS), in collaboration with George Mason University, surveyed a random sample of ATS members to assess their perceptions of, clinical experiences with, and preferred policy responses to climate change. An e-mail containing an invitation from the ATS President and a link to an online survey was sent to 5,500 randomly selected U.S. members; up to four reminder e-mails were sent to nonrespondents. Responses were received from members in 49 states and the District of Columbia (n = 915); the response rate was 17%. Geographic distribution of respondents mirrored that of the sample. Survey estimates' confidence intervals were ±3.5% or smaller. Results indicate that a large majority of ATS members have concluded that climate change is happening (89%), that it is driven by human activity (68%), and that it is relevant to patient care ("a great deal"/"a moderate amount") (65%). A majority of respondents indicated they were already observing health impacts of climate change among their patients, most commonly as increases in chronic disease severity from air pollution (77%), allergic symptoms from exposure to plants or mold (58%), and severe weather injuries (57%). A larger majority anticipated seeing these climate-related health impacts in the next 2 decades. Respondents indicated that physicians and physician organizations should play an active role in educating patients, the public, and policy makers on the human health effects of climate change. Overall, ATS members are observing that human health is already adversely affected by climate change and support responses to address this situation.

A tale of two cities: stigma and health outcomes among people with HIV who inject drugs in St. Petersburg, Russia and Kohtla-Järve, Estonia.

PubMed

Burke, Sara E; Calabrese, Sarah K; Dovidio, John F; Levina, Olga S; Uusküla, Anneli; Niccolai, Linda M; Abel-Ollo, Katri; Heimer, Robert

2015-04-01

Experiences of stigma are often associated with negative mental and physical health outcomes. The present work tested the associations between stigma and health-related outcomes among people with HIV who inject drugs in Kohtla-Järve, Estonia and St. Petersburg, Russia. These two cities share some of the highest rates of HIV outside of sub-Saharan Africa, largely driven by injection drug use, but Estonia has implemented harm reduction services more comprehensively. People who inject drugs were recruited using respondent-driven sampling; those who indicated being HIV-positive were included in the present sample (n = 381 in St. Petersburg; n = 288 in Kohtla-Järve). Participants reported their health information and completed measures of internalized HIV stigma, anticipated HIV stigma, internalized drug stigma, and anticipated drug stigma. Participants in both locations indicated similarly high levels of all four forms of stigma. However, stigma variables were more strongly associated with health outcomes in Russia than in Estonia. The St. Petersburg results were consistent with prior work linking stigma and health. Lower barriers to care in Kohtla-Järve may help explain why social stigma was not closely tied to negative health outcomes there. Implications for interventions and health policy are discussed. Copyright © 2015 Elsevier Ltd. All rights reserved.

Estimating the Size of the Methamphetamine-Using Population in New York City Using Network Sampling Techniques.

PubMed

Dombrowski, Kirk; Khan, Bilal; Wendel, Travis; McLean, Katherine; Misshula, Evan; Curtis, Ric

2012-12-01

As part of a recent study of the dynamics of the retail market for methamphetamine use in New York City, we used network sampling methods to estimate the size of the total networked population. This process involved sampling from respondents' list of co-use contacts, which in turn became the basis for capture-recapture estimation. Recapture sampling was based on links to other respondents derived from demographic and "telefunken" matching procedures-the latter being an anonymized version of telephone number matching. This paper describes the matching process used to discover the links between the solicited contacts and project respondents, the capture-recapture calculation, the estimation of "false matches", and the development of confidence intervals for the final population estimates. A final population of 12,229 was estimated, with a range of 8235 - 23,750. The techniques described here have the special virtue of deriving an estimate for a hidden population while retaining respondent anonymity and the anonymity of network alters, but likely require larger sample size than the 132 persons interviewed to attain acceptable confidence levels for the estimate.

Post-sampling mortality and non-response patterns in the English Cancer Patient Experience Survey: Implications for epidemiological studies based on surveys of cancer patients.

PubMed

Abel, Gary A; Saunders, Catherine L; Lyratzopoulos, Georgios

2016-04-01

Surveys of the experience of cancer patients are increasingly being introduced in different countries and used in cancer epidemiology research. Sampling processes, post-sampling mortality and survey non-response can influence the representativeness of cancer patient surveys. We examined predictors of post-sampling mortality and non-response among patients initially included in the sampling frame of the English Cancer Patient Experience Survey. We also compared the respondents' diagnostic case-mix to other relevant populations of cancer patients, including incident and prevalent cases. Of 109,477 initially sampled cancer patients, 6273 (5.7%) died between sampling and survey mail-out. Older age and diagnosis of brain, lung and pancreatic cancer were associated with higher risk of post-sampling mortality. The overall response rate was 67% (67,713 respondents), being >70% for the most affluent patients and those diagnosed with colon or breast cancer and <50% for Asian or Black patients, those under 35 and those diagnosed with brain cancer. The diagnostic case-mix of respondents varied substantially from incident or prevalent cancer cases. Respondents to the English Cancer Patient Experience Survey represent a population of recently treated cancer survivors. Although patient survey data can provide unique insights for improving cancer care quality, features of survey populations need to be acknowledged when analysing and interpreting findings from studies using such data. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Socially Desirable Responding and the Factorial Stability of the NEO PI-R

ERIC Educational Resources Information Center

Marshall, Margarita B.; De Fruyt, Filip; Rolland, Jean-Pierre; Bagby, R. Michael

2005-01-01

The goal of the present investigation is to compare the factor structure of the revised NEO Personality Inventory (NEO PI-R; P. T. Costa & R. R. McCrae, 1992) in samples of respondents differentially motivated to respond in a socially desirable manner. In the French sample, the authors compared the NEO PI-R structure of job applicants…

A Comparison of EPI Sampling, Probability Sampling, and Compact Segment Sampling Methods for Micro and Small Enterprises

PubMed Central

Chao, Li-Wei; Szrek, Helena; Peltzer, Karl; Ramlagan, Shandir; Fleming, Peter; Leite, Rui; Magerman, Jesswill; Ngwenya, Godfrey B.; Pereira, Nuno Sousa; Behrman, Jere

2011-01-01

Finding an efficient method for sampling micro- and small-enterprises (MSEs) for research and statistical reporting purposes is a challenge in developing countries, where registries of MSEs are often nonexistent or outdated. This lack of a sampling frame creates an obstacle in finding a representative sample of MSEs. This study uses computer simulations to draw samples from a census of businesses and non-businesses in the Tshwane Municipality of South Africa, using three different sampling methods: the traditional probability sampling method, the compact segment sampling method, and the World Health Organization’s Expanded Programme on Immunization (EPI) sampling method. Three mechanisms by which the methods could differ are tested, the proximity selection of respondents, the at-home selection of respondents, and the use of inaccurate probability weights. The results highlight the importance of revisits and accurate probability weights, but the lesser effect of proximity selection on the samples’ statistical properties. PMID:22582004

Addiction and treatment experiences among active methamphetamine users recruited from a township community in Cape Town, South Africa: a mixed-methods study

PubMed Central

Meade, Christina S.; Towe, Sheri L.; Watt, Melissa H.; Lion, Ryan R.; Myers, Bronwyn; Skinner, Donald; Kimani, Stephen; Pieterse, Desiree

2015-01-01

Background Since 2000, there has been a dramatic increase in methamphetamine use in South Africa, but little is known about the experiences of out-of-treatment users. This mixed-methods study describes the substance use histories, addiction symptoms, and treatment experiences of a community-recruited sample of methamphetamine users in Cape Town. Methods Using respondent driven sampling, 360 methamphetamine users (44% female) completed structured clinical interviews to assess substance abuse and treatment history and computerized surveys to assess drug-related risks. A sub-sample of 30 participants completed in-depth interviews to qualitatively explore experiences with methamphetamine use and drug treatment. Results Participants had used methamphetamine for an average of 7.06 years (SD=3.64). They reported using methamphetamine on an average of 23.49 of the past 30 days (SD=8.90); 60% used daily. The majority (90%) met ICD-10 criteria for dependence, and many reported severe social, financial, and legal consequences. While only 10% had ever received drug treatment, 90% reported that they wanted treatment. In the qualitative interviews, participants reported multiple barriers to treatment, including beliefs that treatment is ineffective and relapse is inevitable in their social context. They also identified important motivators, including desires to be drug free and improve family functioning. Conclusion This study yields valuable information to more effectively respond to emerging methamphetamine epidemics in South Africa and other low- and middle-income countries. Interventions to increase uptake of evidence-based services must actively seek out drug users and build motivation for treatment, and offer continuing care services to prevent relapse. Community education campaigns are also needed. PMID:25977205

Structural bridging network position is associated with HIV status in a younger Black men who have sex with men epidemic.

PubMed

Shah, Nirav S; Iveniuk, James; Muth, Stephen Q; Michaels, Stuart; Jose, Jo-Anne; Laumann, Edward O; Schneider, John A

2014-02-01

Younger Black men who have sex with men (BMSM) ages 16-29 have the highest rates of HIV in the United States. Despite increased attention to social and sexual networks as a framework for biomedical intervention, the role of measured network positions, such as bridging and their relationship to HIV risk has received limited attention. A network sample (N = 620) of BMSM respondents (N = 154) and their MSM and transgendered person network members (N = 466) was generated through respondent driven sampling of BMSM and elicitation of their personal networks. Bridging status of each network member was determined by a constraint measure and was used to assess the relationship between this bridging and unprotected anal intercourse (UAI), sex-drug use (SDU), group sex (GS) and HIV status within the network in South Chicago. Low, moderate and high bridging was observed in 411 (66.8 %), 81 (13.2 %) and 123 (20.0 %) of the network. In addition to age and having sex with men only, moderate and high levels of bridging were associated with HIV status (aOR 3.19; 95 % CI 1.58-6.45 and aOR 3.83; 95 % CI 1.23-11.95, respectively). Risk behaviors observed including UAS, GS, and SDU were not associated with HIV status, however, they clustered together in their associations with one another. Bridging network position but not risk behavior was associated with HIV status in this network sample of younger BMSM. Socio-structural features such as position within the network may be important when implementing effective HIV prevention interventions in younger BMSM populations.

Optical gain in 1.3-μm electrically driven dilute nitride VCSOAs

PubMed Central

2014-01-01

We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain. PMID:24417791

The role of affect-driven impulsivity in gambling cognitions: A convenience-sample study with a Spanish version of the Gambling-Related Cognitions Scale.

PubMed

Del Prete, Francesco; Steward, Trevor; Navas, Juan F; Fernández-Aranda, Fernando; Jiménez-Murcia, Susana; Oei, Tian P S; Perales, José C

2017-03-01

Background and aims Abnormal cognitions are among the most salient domain-specific features of gambling disorder. The aims of this study were: (a) to examine and validate a Spanish version of the Gambling-Related Cognitions Scale (GRCS; Raylu & Oei, 2004) and (b) to examine associations between cognitive distortion levels, impulsivity, and gambling behavior. Methods This study first recruited a convenience sample of 500 adults who had gambled during the previous year. Participants were assessed using the Spanish version of GRCS (GRCS-S) questionnaire, the UPPS-P impulsivity questionnaire, measures of gambling behavior, and potentially relevant confounders. Robust confirmatory factor analysis methods on half the sample were used to select the best models from a hypothesis-driven set. The best solutions were validated on the other half, and the resulting factors were later correlated with impulsivity dimensions (in the whole n = 500 factor analysis sample) and clinically relevant gambling indices (in a separate convenience sample of 137 disordered and non-disordered gamblers; validity sample). Results This study supports the original five-factor model, suggests an alternative four-factor solution, and confirms the psychometric soundness of the GRCS-S. Importantly, cognitive distortions consistently correlated with affect- or motivation-driven aspects of impulsivity (urgency and sensation seeking), but not with cognitive impulsivity (lack of premeditation and lack of perseverance). Discussion and conclusions Our findings suggest that the GRCS-S is a valid and reliable instrument to identify gambling cognitions in Spanish samples. Our results expand upon previous research signaling specific associations between gambling-related distortions and affect-driven impulsivity in line with models of motivated reasoning.

The role of affect-driven impulsivity in gambling cognitions: A convenience-sample study with a Spanish version of the Gambling-Related Cognitions Scale

PubMed Central

Del Prete, Francesco; Steward, Trevor; Navas, Juan F.; Fernández-Aranda, Fernando; Jiménez-Murcia, Susana; Oei, Tian P. S.; Perales, José C.

2017-01-01

Background and aims Abnormal cognitions are among the most salient domain-specific features of gambling disorder. The aims of this study were: (a) to examine and validate a Spanish version of the Gambling-Related Cognitions Scale (GRCS; Raylu & Oei, 2004) and (b) to examine associations between cognitive distortion levels, impulsivity, and gambling behavior. Methods This study first recruited a convenience sample of 500 adults who had gambled during the previous year. Participants were assessed using the Spanish version of GRCS (GRCS-S) questionnaire, the UPPS-P impulsivity questionnaire, measures of gambling behavior, and potentially relevant confounders. Robust confirmatory factor analysis methods on half the sample were used to select the best models from a hypothesis-driven set. The best solutions were validated on the other half, and the resulting factors were later correlated with impulsivity dimensions (in the whole n = 500 factor analysis sample) and clinically relevant gambling indices (in a separate convenience sample of 137 disordered and non-disordered gamblers; validity sample). Results This study supports the original five-factor model, suggests an alternative four-factor solution, and confirms the psychometric soundness of the GRCS-S. Importantly, cognitive distortions consistently correlated with affect- or motivation-driven aspects of impulsivity (urgency and sensation seeking), but not with cognitive impulsivity (lack of premeditation and lack of perseverance). Discussion and conclusions Our findings suggest that the GRCS-S is a valid and reliable instrument to identify gambling cognitions in Spanish samples. Our results expand upon previous research signaling specific associations between gambling-related distortions and affect-driven impulsivity in line with models of motivated reasoning. PMID:28118729

Feasibility of Recruiting a Diverse Sample of Men Who Have Sex with Men: Observation from Nanjing, China

PubMed Central

Tang, Weiming; Yang, Haitao; Mahapatra, Tanmay; Huan, Xiping; Yan, Hongjing; Li, Jianjun; Fu, Gengfeng; Zhao, Jinkou; Detels, Roger

2013-01-01

Background Respondent-driven-sampling (RDS) has well been recognized as a method for sampling from most hard-to-reach populations like commercial sex workers, drug users and men who have sex with men. However the feasibility of this sampling strategy in terms of recruiting a diverse spectrum of these hidden populations has not been understood well yet in developing countries. Methods In a cross sectional study in Nanjing city of Jiangsu province of China, 430 MSM were recruited including 9 seeds in 14 weeks of study period using RDS. Information regarding socio-demographic characteristics and sexual risk behavior were collected and testing was done for HIV and syphilis. Duration, completion, participant characteristics and the equilibrium of key factors were used for assessing feasibility of RDS. Homophily of key variables, socio-demographic distribution and social network size were used as the indicators of diversity. Results In the study sample, adjusted HIV and syphilis prevalence were 6.6% and 14.6% respectively. Majority (96.3%) of the participants were recruited by members of their own social network. Although there was a tendency for recruitment within the same self-identified group (homosexuals recruited 60.0% homosexuals), considerable cross-group recruitment (bisexuals recruited 52.3% homosexuals) was also seen. Homophily of the self-identified sexual orientations was 0.111 for homosexuals. Upon completion of the recruitment process, participant characteristics and the equilibrium of key factors indicated that RDS was feasible for sampling MSM in Nanjing. Participants recruited by RDS were found to be diverse after assessing the homophily of key variables in successive waves of recruitment, the proportion of characteristics after reaching equilibrium and the social network size. The observed design effects were nearly the same or even better than the theoretical design effect of 2. Conclusion RDS was found to be an efficient and feasible sampling method for recruiting a diverse sample of MSM in a reasonable time. PMID:24244280

Factors associated with syphilis seroreactivity among polydrug users in Northeast Brazil: A cross-sectional study using Respondent Driven Sampling.

PubMed

Baptista, Cremildo João; Dourado, Ines; Brignol, Sandra; Andrade, Tarcísio de Matos; Bastos, Francisco Inácio

2017-01-01

The burden of sexually transmitted infections (STIs), such as syphilis, is higher in low-income countries, with serious consequences and profound impact on sexual and reproductive health and human immunodeficiency virus (HIV) spread. Syphilis prevalence tend to be higher among people who misuse drugs than in the general population. To assess syphilis and associated factors among polydrug users (PDU) in the city of Salvador, Northeast Brazil. A cross-sectional study was conducted in 10 Brazilian cities between September and November 2009 using Respondent Driven Sampling (RDS). Participants answered an Audio Computer-Assisted Self Interview (ACASI) and were rapid tested for HIV and syphilis. We performed multivariable regression models for correlates of syphilis on Stata 10.0. Estimates were weighted by the inverse size of the individual social network size and homophily. Mean age was 29.3 years (range: 18-62), 74.0% were males, and 89.8% were non-white. Syphilis prevalence was 16.6%. Females (adjwOR:2.14; 95%CI:1.09-4.20), individuals over 29 years old (adjwOR:4.44; 95%CI:2.41-8.19), those who exchanged sex for money or drugs (adjwOR:3.51; 95%CI:1.84-6.71), "No/low" self-perceived risk of HIV infection (adjwOR:5.13; 95%CI:1.36-19.37), and having nine or less years of education (adjwOR:2.92; 95%CI:1.08-7.88) were associated with syphilis. One of the most pressing needs for syphilis prevention/control is the availability of rapid point-of-care diagnostic tests and treatment. Interventions should be tailored to PDU needs and their multiple burdens as shown in the present study, that may contribute to future studies aiming to better understand the relationships between drug use and syphilis. Copyright © 2016 Elsevier B.V. All rights reserved.

The complex interplay of social networks, geography and HIV risk among Malaysian Drug Injectors: Results from respondent-driven sampling.

PubMed

Zelenev, Alexei; Long, Elisa; Bazazi, Alexander R; Kamarulzaman, Adeeba; Altice, Frederick L

2016-11-01

HIV is primarily concentrated among people who inject drugs (PWID) in Malaysia, where currently HIV prevention and treatment coverage is inadequate. To improve the targeting of interventions, we examined HIV clustering and the role that social networks and geographical distance play in influencing HIV transmission among PWID. Data were derived from a respondent-driven survey sample (RDS) collected during 2010 of 460 PWID in greater Kuala Lumpur. Analysis focused on socio-demographic, clinical, behavioural, and network information. Spatial probit models were developed based on a distinction between the influence of peers (individuals nominated through a recruitment network) and neighbours (residing a close distance to the individual). The models were expanded to account for the potential influence of the network formation. Recruitment patterns of HIV-infected PWID clustered both spatially and across the recruitment networks. In addition, HIV-infected PWID were more likely to have peers and neighbours who inject with clean needles were HIV-infected and lived nearby (<5km), more likely to have been previously incarcerated, less likely to use clean needles (26.8% vs 53.0% of the reported injections, p<0.01), and have fewer recent injection partners (2.4 vs 5.4, p<0.01). The association between the HIV status of peers and neighbours remained significantly correlated even after controlling for unobserved variation related to network formation and sero-sorting. The relationship between HIV status across networks and space in Kuala Lumpur underscores the importance of these factors for surveillance and prevention strategies, and this needs to be more closely integrated. RDS can be applied to identify injection network structures, and this provides an important mechanism for improving public health surveillance, accessing high-risk populations, and implementing risk-reduction interventions to slow HIV transmission. Copyright © 2016 Elsevier B.V. All rights reserved.

An analysis of respondent-driven sampling with injecting drug users in a high HIV prevalent state of India.

PubMed

Phukan, Sanjib Kumar; Medhi, Gajendra Kumar; Mahanta, Jagadish; Adhikary, Rajatashuvra; Thongamba, Gay; Paranjape, Ramesh S; Akoijam, Brogen S

2017-07-03

Personal networks are significant social spaces to spread of HIV or other blood-borne infections among hard-to-reach population, viz., injecting drug users, female sex workers, etc. Sharing of infected needles or syringes among drug users is one of the major routes of HIV transmission in Manipur, a high HIV prevalence state in India. This study was carried out to describe the network characteristics and recruitment patterns of injecting drug users and to assess the association of personal network with injecting risky behaviors in Manipur. A total of 821 injecting drug users were recruited into the study using respondent-driven sampling (RDS) from Bishnupur and Churachandpur districts of Manipur; data on demographic characteristics, HIV risk behaviors, and network size were collected from them. Transition probability matrices and homophily indices were used to describe the network characteristics, and recruitment patterns of injecting drug users. Univariate and multivariate binary logistic regression models were performed to analyze the association between the personal networks and sharing of needles or syringes. The average network size was similar in both the districts. Recruitment analysis indicates injecting drug users were mostly engaged in mixed age group setting for injecting practice. Ever married and new injectors showed lack of in-group ties. Younger injecting drug users had mainly recruited older injecting drug users from their personal network. In logistic regression analysis, higher personal network was found to be significantly associated with increased likelihood of injecting risky behaviors. Because of mixed personal network of new injectors and higher network density associated with HIV exposure, older injecting drug users may act as a link for HIV transmission or other blood-borne infections to new injectors and also to their sexual partners. The information from this study may be useful to understanding the network pattern of injecting drug users for enriching the HIV prevention in this region.

Prevalence and patterns of victimization and polyvictimization among female sex workers in Soweto, a South African township: a cross-sectional, respondent-driven sampling study

PubMed Central

Coetzee, J.; Gray, G. E.; Jewkes, R.

2017-01-01

ABSTRACT Background: Female sex workers (FSWs) are disproportionately affected by violence from multiple partner categories. This increases their vulnerability to HIV. Objectives: To describe patterns of violence and polyvictimization among female SWs in Soweto. Methods: A respondent-driven sampling (RDS) recruitment methodology was used to enrol 508 Soweto-based FSWs using a survey instrument. Raw and RDS adjusted data were descriptively analysed, Spearman’s correlation and chi2 test of association were used to show associations. Polyvictimization patterns are shown within a modified Venn diagram. Results: The median age of FSWs in Soweto was 31 years, and most had an incomplete education (74.2%). The prevalence of exposure to physical/sexual intimate partner violence (IPV) in the past year was 53.8%, 46.8% by clients, and 18.5% by police. Past year prevalence of sexual/physical violence by any perpetrator category was 70.8% and lifetime exposure was 76.0%. Childhood sexual violence was reported by 44.3%. Lifetime non-partner rape was 55.5% and all rape exposure was 62.4%. As a result of engaging in sex work in the past year, 65.2% women had been discriminated against. Client, police, IPV, and childhood trauma were all significantly associated with one another, with IPV being the most common co-occurrence. Polyvictimization was seen in almost two-thirds of FSWs, and increased with exposure to discrimination. Conclusion: In Soweto, FSWs are exposed to high rates of violence in multiple forms across their lifetime. Our findings show that violence continues unabated into adulthood at levels far higher than in the general population and overall at higher levels than previously recorded among SWs in South Africa. We argue that violence against FSWs is rooted in discrimination. The disparate burden of violence on FSWs requires urgent interventions to proactively address and reframe the normalisation of violence against all women. PMID:29211633

Respondent-driven sampling on the Thailand-Cambodia border. I. Can malaria cases be contained in mobile migrant workers?

PubMed Central

2011-01-01

Background Reliable information on mobility patterns of migrants is a crucial part of the strategy to contain the spread of artemisinin-resistant malaria parasites in South-East Asia, and may also be helpful to efforts to address other public health problems for migrants and members of host communities. In order to limit the spread of malarial drug resistance, the malaria prevention and control programme will need to devise strategies to reach cross-border and mobile migrant populations. Methodology The Respondent-driven sampling (RDS) method was used to survey migrant workers from Cambodia and Myanmar, both registered and undocumented, in three Thai provinces on the Thailand-Cambodia border in close proximity to areas with documented artemisinin-resistant malaria parasites. 1,719 participants (828 Cambodian and 891 Myanmar migrants) were recruited. Subpopulations of migrant workers were analysed using the Thailand Ministry of Health classification based on length of residence in Thailand of greater than six months (long-term, or M1) or less than six months (short-term, or M2). Key information collected on the structured questionnaire included patterns of mobility and migration, demographic characteristics, treatment-seeking behaviours, and knowledge, perceptions, and practices about malaria. Results Workers from Cambodia came from provinces across Cambodia, and 22% of Cambodian M1 and 72% of Cambodian M2 migrants had been in Cambodia in the last three months. Less than 6% returned with a frequency of greater than once per month. Of migrants from Cambodia, 32% of M1 and 68% of M2 were planning to return, and named provinces across Cambodia as their likely next destinations. Most workers from Myanmar came from Mon state (86%), had never returned to Myanmar (85%), and only 4% stated plans to return. Conclusion Information on migratory patterns of migrants from Myanmar and Cambodia along the malaria endemic Thailand-Cambodian border within the artemisinin resistance containment zone will help target health interventions, including treatment follow-up and surveillance. PMID:21554744

Intervenable factors associated with suicide risk in transgender persons: a respondent driven sampling study in Ontario, Canada.

PubMed

Bauer, Greta R; Scheim, Ayden I; Pyne, Jake; Travers, Robb; Hammond, Rebecca

2015-06-02

Across Europe, Canada, and the United States, 22-43 % of transgender (trans) people report a history of suicide attempts. We aimed to identify intervenable factors (related to social inclusion, transphobia, or sex/gender transition) associated with reduced risk of past-year suicide ideation or attempt, and to quantify the potential population health impact. The Trans PULSE respondent-driven sampling (RDS) survey collected data from trans people age 16+ in Ontario, Canada, including 380 who reported on suicide outcomes. Descriptive statistics and multivariable logistic regression models were weighted using RDS II methods. Counterfactual risk ratios and population attributable risks were estimated using model-standardized risks. Among trans Ontarians, 35.1 % (95 % CI: 27.6, 42.5) seriously considered, and 11.2 % (95 % CI: 6.0, 16.4) attempted, suicide in the past year. Social support, reduced transphobia, and having any personal identification documents changed to an appropriate sex designation were associated with large relative and absolute reductions in suicide risk, as was completing a medical transition through hormones and/or surgeries (when needed). Parental support for gender identity was associated with reduced ideation. Lower self-reported transphobia (10(th) versus 90(th) percentile) was associated with a 66 % reduction in ideation (RR = 0.34, 95 % CI: 0.17, 0.67), and an additional 76 % reduction in attempts among those with ideation (RR = 0.24; 95 % CI: 0.07, 0.82). This corresponds to potential prevention of 160 ideations per 1000 trans persons, and 200 attempts per 1,000 with ideation, based on a hypothetical reduction of transphobia from current levels to the 10(th) percentile. Large effect sizes were observed for this controlled analysis of intervenable factors, suggesting that interventions to increase social inclusion and access to medical transition, and to reduce transphobia, have the potential to contribute to substantial reductions in the extremely high prevalences of suicide ideation and attempts within trans populations. Such interventions at the population level may require policy change.

Reported emergency department avoidance, use, and experiences of transgender persons in Ontario, Canada: results from a respondent-driven sampling survey.

PubMed

Bauer, Greta R; Scheim, Ayden I; Deutsch, Madeline B; Massarella, Carys

2014-06-01

Transgender, transsexual, or transitioned (trans) people have reported avoiding medical care because of negative experiences or fear of such experiences. The extent of trans-specific negative emergency department (ED) experiences, and of ED avoidance, has not been documented. The Trans PULSE Project conducted a survey of trans people in Ontario, Canada (n=433) in 2009 to 2010, using respondent-driven sampling, a tracked network-based method for studying hidden populations. Weighted frequencies and bootstrapped 95% confidence intervals (CIs) were estimated for the trans population in Ontario and for the subgroup (n=167) reporting ED use in their felt gender. Four hundred eight participants completed the ED experience items. Trans people were young (34% aged 16 to 24 years and only 10% >55 years); approximately half were female-to-male and half male-to-female. Medically supervised hormones were used by 37% (95% CI 30% to 46%), and 27% (95% CI 20% to 35%) had at least 1 transition-related surgery. Past-year ED need was reported by 33% (95% CI 26% to 40%) of trans Ontarians, though only 71% (95% CI 40% to 91%) of those with self-reported need indicated that they were able to obtain care. An estimated 21% (95% CI 14% to 25%) reported ever avoiding ED care because of a perception that their trans status would negatively affect such an encounter. Trans-specific negative ED experiences were reported by 52% (95% CI 34% to 72%) of users presenting in their felt gender. This first exploratory analysis of ED avoidance, utilization, and experiences by trans persons documented ED avoidance and possible unmet need for emergency care among trans Ontarians. Additional research, including validation of measures, is needed. Copyright © 2013 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

Respondent-driven sampling to assess mental health outcomes, stigma and acceptance among women raising children born from sexual violence-related pregnancies in eastern Democratic Republic of Congo

PubMed Central

Scott, Jennifer; Rouhani, Shada; Greiner, Ashley; Albutt, Katherine; Kuwert, Philipp; Hacker, Michele R; VanRooyen, Michael; Bartels, Susan

2015-01-01

Objectives Assess mental health outcomes among women raising children from sexual violence-related pregnancies (SVRPs) in eastern Democratic Republic of Congo and stigma toward and acceptance of women and their children. Design Participants were recruited using respondent-driven sampling. Setting Bukavu, Democratic Republic of Congo in 2012. Participants 757 adult women raising children from SVRPs were interviewed. A woman aged 18 and older was eligible for the study if she self-identified as a sexual violence survivor since the start of the conflict (∼1996), conceived an SVRP, delivered a liveborn child and was currently raising the child. A woman was ineligible for the study if the SVRP ended with a spontaneous abortion or fetal demise or the child was not currently living or in the care of the biological mother. Intervention Trained female Congolese interviewers verbally administered a quantitative survey after obtaining verbal informed consent. Outcome measures Symptom criteria for major depressive disorder, post-traumatic stress disorder, anxiety and suicidality were assessed, as well as stigma toward the woman and her child. Acceptance of the woman and child from the spouse, family and community were analysed. Results 48.6% met symptom criteria for major depressive disorder, 57.9% for post-traumatic stress disorder, 43.3% for anxiety and 34.2% reported suicidality. Women who reported stigma from the community (38.4%) or who reported stigma toward the child from the spouse (42.9%), family (31.8%) or community (38.1%) were significantly more likely to meet symptom criteria for most mental health disorders. Although not statistically significant, participants who reported acceptance and acceptance of their children from the spouse, family and community were less likely to meet symptom criteria. Conclusions Women raising children from SVRPs experience symptoms of mental health disorders. Programming addressing stigma and acceptance following sexual violence may improve mental health outcomes in this population. PMID:25854968

Prevalence and patterns of victimization and polyvictimization among female sex workers in Soweto, a South African township: a cross-sectional, respondent-driven sampling study.

PubMed

Coetzee, J; Gray, G E; Jewkes, R

2017-01-01

Female sex workers (FSWs) are disproportionately affected by violence from multiple partner categories. This increases their vulnerability to HIV. To describe patterns of violence and polyvictimization among female SWs in Soweto. A respondent-driven sampling (RDS) recruitment methodology was used to enrol 508 Soweto-based FSWs using a survey instrument. Raw and RDS adjusted data were descriptively analysed, Spearman's correlation and chi 2 test of association were used to show associations. Polyvictimization patterns are shown within a modified Venn diagram. The median age of FSWs in Soweto was 31 years, and most had an incomplete education (74.2%). The prevalence of exposure to physical/sexual intimate partner violence (IPV) in the past year was 53.8%, 46.8% by clients, and 18.5% by police. Past year prevalence of sexual/physical violence by any perpetrator category was 70.8% and lifetime exposure was 76.0%. Childhood sexual violence was reported by 44.3%. Lifetime non-partner rape was 55.5% and all rape exposure was 62.4%. As a result of engaging in sex work in the past year, 65.2% women had been discriminated against. Client, police, IPV, and childhood trauma were all significantly associated with one another, with IPV being the most common co-occurrence. Polyvictimization was seen in almost two-thirds of FSWs, and increased with exposure to discrimination. In Soweto, FSWs are exposed to high rates of violence in multiple forms across their lifetime. Our findings show that violence continues unabated into adulthood at levels far higher than in the general population and overall at higher levels than previously recorded among SWs in South Africa. We argue that violence against FSWs is rooted in discrimination. The disparate burden of violence on FSWs requires urgent interventions to proactively address and reframe the normalisation of violence against all women.

Use of Theory-Driven Research in Counseling: Investigating Three Counseling Psychology Journals from 1990 to 1999

ERIC Educational Resources Information Center

Karr, Carolyn A.; Larson, Lisa M.

2005-01-01

Three major journals in counseling psychology were sampled from 1990 to 1999 to assess the percentage of quantitative, empirical articles that were theory driven. Only 43% of the studies utilized a theory or model, and 57% predicted the relation between the variables, with few studies specifying the strength of the relation. Studies sampled in the…

Correlates of exchange sex among a population-based sample of low-income women who have heterosexual sex in Baltimore.

PubMed

Sherman, Susan G; Hast, Marisa; Park, Ju Nyeong; Decker, Michele R; Flynn, Colin; German, Danielle

2018-03-08

Sex exchange is associated with HIV and other morbidities yet has received little research, surveillance, and programmatic attention in the U.S. This study identified correlates of exchange sex and among low-income women in Baltimore, Maryland. Participants were recruited into the National HIV Behavioral Surveillance (NHBS) system in 2013 using respondent driven sampling (RDS) and completed a survey and HIV testing. The analytic sample (n = 253) consisted of women aged ≥18 years who had recent (past year) heterosexual sex. Multivariable logistic regression identified correlates of recent exchange sex. Independently associated with recent exchange sex were history of injection drug use (adjusted odds ratio (AOR) = 3.4, 95% CI: 1.1-10.3), recent prescription painkiller use (AOR = 3.7, 95% CI: 1.4-9.9), recent crack/cocaine use (AOR = 6.6, 95% CI: 2.1-20.9), recent arrest (AOR = 4.1, 95% CI: 1.2-14.8), and recent consistent condom use (AOR 1.1; 95% CI: 1.0-1.3). Women who exchanged sex exhibited heightened social and structural vulnerability and substance use. These data demonstrate the need for further research examining the context of exchange sex among low-income women and synergies between substance use and HIV risk.

Severity of club drug dependence and perceived need for treatment among a sample of adult club drug users in Shanghai, China

PubMed Central

Ding, Yingying; He, Na; Shoptaw, Steven; Gao, Meiyang; Detels, Roger

2013-01-01

Purpose Examine the severity of club drug dependence and perceived need for treatment, and further identify their determinants among a sample of club drug users in Shanghai, China. Methods 276 club drug users were recruited using respondent-driven sampling (RDS). Severity of dependence on club drugs was measured using the Severity of Dependence Scale (SDS). Results 69.9% reported dependence on club drugs (i.e., SDS≥4) and 36.6% reported severe dependence (i.e., SDS≥6). One eighth (12.7%) perceived need for drug treatment. Severe dependence on club drugs was more likely among those who reported recent use of ecstasy and those who had more depressive symptoms, but less likely among those reporting recent use of methamphetamine. Perceived need for treatment was more likely among those who lived with a spouse or boy/girlfriend, but less likely among those had prior drug treatment experience and more severe club drug dependence. Conclusions Our findings suggest that educational activities should be implemented to raise public awareness about the powerful addictive properties of club drugs, along with efforts to reduce stigma towards drug abuse and psychiatric disorders. Programs to motivate drug users to seek treatment and encourage treatment linkage are urgently needed. PMID:23715971

Unveiling HIV dynamics among transgender women: a respondent driven sampling study in Rio de Janeiro, Brazil

PubMed Central

Grinsztejn, Beatriz; Jalil, Emilia Moreira; Monteiro, Laylla; Velasque, Luciane; Moreira, Ronaldo I.; Garcia, Ana Cristina F.; Castro, Cristiane V.; Krüger, Alícia; Luz, Paula M.; Liu, Albert Y.; Farland, Willi Mc; Buchbinder, Susan; Veloso, Valdilea G.; Wilson, Erin C.

2017-01-01

Background The burden of HIV in transgender women (transwomen) in Brazil remains unknown. We aimed to estimate HIV prevalence among transwomen, and identify the factors associated with newly diagnosed HIV infections. Methods “Transcender” was a respondent driven sampling study of transwomen in Rio de Janeiro, Brazil, conducted from August 2015 to January 2016. Twelve seeds were recruited from social movements and formative phase. Eligibility criteria were: self-identification as transwomen, being 18 years of age or older, living in Rio de Janeiro or metropolitan area, and having a valid peer recruitment coupon. Participants were categorized as HIV-negative, known HIV infected, or newly diagnosed as HIV infected. Predictors of newly diagnosed HIV infections were assessed by comparing the newly diagnosed with the HIV-negative. Population estimates were adjusted using the RDSII estimator. Findings In total, 345 eligible transwomen were enrolled. The study sample was young and diverse on gender identity. Population estimates of no prior HIV testing, HIV-infection and newly diagnosed as HIV-infected were 29·1%, 32·1% and 7·0%, respectively (based on n=60 with no prior testing, n=141 HIV-infected, n=40 newly diagnosed). Syphilis, rectal chlamydia and gonorrhea infection were diagnosed in 28·9%, 14·6%, and 13·5%, respectively. Newly diagnosed HIV infections were associated with black race (22·8; 95%CI 2·9–178·9), travesti (34·1; 95%CI 5·8–200·2) or transsexual woman (41·3; 95%CI 6·3–271·2) gender identity, history of sex work (30·7; 95%CI 3·5–267·3), and history of sniffing cocaine (4·4; 95%CI 1·4–14·1). Interpretation Our results suggest that transwomen bear the largest burden of HIV among any population at risk in Brazil. The high proportion of HIV diagnosis among young participants points to the need for tailored long-term health care and prevention services in order to curb the HIV epidemic and improve the quality-of-life of transwomen in Brazil. Funding This work was supported by Brazilian Research Council (470056/2014-2) and NIAID-NIH (UM1AI069496). PMID:28188030

On the Origins of Emergent Differential Sample Behavior

ERIC Educational Resources Information Center

Urcuioli, Peter J.; Vasconcelos, Marco

2008-01-01

Two experiments evaluated the source(s) of emergent differential sample behavior in pigeons. Initially, pigeons learned two-sample, two-alternative symbolic matching in which different patterns of sample responding were required to produce the comparisons. Afterwards, two other samples nominally identical to the comparisons were added to the…

Convectively driven PCR thermal-cycling

DOEpatents

Benett, William J.; Richards, James B.; Milanovich, Fred P.

2003-07-01

A polymerase chain reaction system provides an upper temperature zone and a lower temperature zone in a fluid sample. Channels set up convection cells in the fluid sample and move the fluid sample repeatedly through the upper and lower temperature zone creating thermal cycling.

An efficient, reliable and inexpensive device for the rapid homogenization of multiple tissue samples by centrifugation.

PubMed

Ilyin, S E; Plata-Salamán, C R

2000-02-15

Homogenization of tissue samples is a common first step in the majority of current protocols for RNA, DNA, and protein isolation. This report describes a simple device for centrifugation-mediated homogenization of tissue samples. The method presented is applicable to RNA, DNA, and protein isolation, and we show examples where high quality total cell RNA, DNA, and protein were obtained from brain and other tissue samples. The advantages of the approach presented include: (1) a significant reduction in time investment relative to hand-driven or individual motorized-driven pestle homogenization; (2) easy construction of the device from inexpensive parts available in any laboratory; (3) high replicability in the processing; and (4) the capacity for the parallel processing of multiple tissue samples, thus allowing higher efficiency, reliability, and standardization.

A country-wide probability sample of public attitudes toward stuttering in Portugal.

PubMed

Valente, Ana Rita S; St Louis, Kenneth O; Leahy, Margaret; Hall, Andreia; Jesus, Luis M T

2017-06-01

Negative public attitudes toward stuttering have been widely reported, although differences among countries and regions exist. Clear reasons for these differences remain obscure. Published research is unavailable on public attitudes toward stuttering in Portugal as well as a representative sample that explores stuttering attitudes in an entire country. This study sought to (a) determine the feasibility of a country-wide probability sampling scheme to measure public stuttering attitudes in Portugal using a standard instrument (the Public Opinion Survey of Human Attributes-Stuttering [POSHA-S]) and (b) identify demographic variables that predict Portuguese attitudes. The POSHA-S was translated to European Portuguese through a five-step process. Thereafter, a local administrative office-based, three-stage, cluster, probability sampling scheme was carried out to obtain 311 adult respondents who filled out the questionnaire. The Portuguese population held stuttering attitudes that were generally within the average range of those observed from numerous previous POSHA-S samples. Demographic variables that predicted more versus less positive stuttering attitudes were respondents' age, region of the country, years of school completed, working situation, and number of languages spoken. Non-predicting variables were respondents' sex, marital status, and parental status. A local administrative office-based, probability sampling scheme generated a respondent profile similar to census data and indicated that Portuguese attitudes are generally typical. Copyright © 2017 Elsevier Inc. All rights reserved.

Derived Relational Responding: A Comparison of Match-to-Sample and the Relational Completion Procedure

ERIC Educational Resources Information Center

Dymond, Simon; Whelan, Robert

2010-01-01

Previous research suggests that the Relational Completion Procedure may be an effective alternative procedure for studying derived relational responding. However, the parameters that make it effective, relative to traditional match-to-sample, remain to be determined. The present experiment compared the Relational Completion Procedure and…

Community-Based Assessment to Inform a Chlamydia Screening Program for Women in a Rural American Indian Community.

PubMed

Smartlowit-Briggs, Lucy; Pearson, Cynthia; Whitefoot, Patricia; Altamirano, Bianca N; Womack, Michelle; Bastin, Marie; Dombrowski, Julia C

2016-06-01

Rates of chlamydial infection in American Indian/Alaska Native women in the United States are approximately 4-fold those in non-Hispanic white women. We conducted a community-based survey of self-identified American Indian/Alaska Native women 14 to 25 years of age on a reservation in the Northwestern United States to inform a chlamydia screening strategy. The anonymous survey assessed respondents' knowledge, perceptions, and preferences related to chlamydia screening, results receipt, and partner notification. We recruited women using respondent-driven sampling, school-based sampling, and direct recruitment through social media and fliers. Participants in schools completed the survey as a paper-based, self-administered survey. Other participants could complete the survey in person, by phone as an interviewer-administered survey, or online. We recruited 162 participants, most in schools (n = 83; 51%) or by peer referral (n = 55; 34%). Only 1 woman completed the survey online. Thirty-one respondents (19%) reported a history of an unplanned first pregnancy, and 19 (12%) reported a history of a diagnosed sexually transmitted disease. Most women (n = 98; 63%) recognized the potential impact of Chlamydia trachomatis on fertility. The preferred site for chlamydia screening was the Indian Health Service Clinic (n = 114; 70%), but 79 women (41%) would accept a C. trachomatis test at a nonclinical testing site. Of the 56 women (35%) who would accept home testing, most preferred to get the test kit from a clinic. Our results suggest that Indian Health Service efforts to increase chlamydia screening in the clinic and through outreach may be more successful than promotion of home testing in this population.

Power, community mobilization, and condom use practices among female sex workers in Andhra Pradesh, India.

PubMed

Blankenship, Kim M; West, Brooke S; Kershaw, Trace S; Biradavolu, Monica R

2008-12-01

We used a structural interventions framework to analyse the associations between power and condom use among a sample of female sex workers (FSW), and how exposure to a local community mobilization intervention (CMI) affects these associations. Data came from a cross-sectional survey of 812 FSW in the East Godavari district of Andhra Pradesh, India, recruited through respondent-driven sampling. We identified three types of power - collective power, control over work, and economic power, and three dimensions of collective power - collective identity, efficacy, and agency. Multivariate logistic regression analysis was used to analyse the relationship of these three types of power and exposure to a CMI with consistent condom use with clients. A total of 803 respondents exchanged sex with an occasional or regular client in the 7 days before the interview. Multivariate logistic regression shows that control over both the type of sex [adjusted odds ratio (AOR) 1.70, 95% confidence interval (CI) 1.23-2.34] and the amount charged (AOR 1.56, 95% CI 1.12-2.16), and economic dependence (AOR 0.54, 95% CI 0.35-0.83) are associated with consistent condom use as is programme exposure (AOR 2.09, 95% CI 1.48-2.94). The interaction between programme exposure and collective agency was also significant (chi-square 6.62, P = 0.01). Among respondents who reported both programme exposure and high levels of collective agency, the odds ratio of consistent condom use was 2.5 times that of other FSW. A structural interventions framework is useful for understanding HIV risk among FSW. More needs to be done to promote FSW control over work and access to economic resources.

Challenges in Estimating Vaccine Coverage in Refugee and Displaced Populations: Results From Household Surveys in Jordan and Lebanon

PubMed Central

Roberton, Timothy; Weiss, William; Doocy, Shannon

2017-01-01

Ensuring the sustained immunization of displaced persons is a key objective in humanitarian emergencies. Typically, humanitarian actors measure coverage of single vaccines following an immunization campaign; few measure routine coverage of all vaccines. We undertook household surveys of Syrian refugees in Jordan and Lebanon, outside of camps, using a mix of random and respondent-driven sampling, to measure coverage of all vaccinations included in the host country’s vaccine schedule. We analyzed the results with a critical eye to data limitations and implications for similar studies. Among households with a child aged 12–23 months, 55.1% of respondents in Jordan and 46.6% in Lebanon were able to produce the child’s EPI card. Only 24.5% of Syrian refugee children in Jordan and 12.5% in Lebanon were fully immunized through routine vaccination services (having received from non-campaign sources: measles, polio 1–3, and DPT 1–3 in Jordan and Lebanon, and BCG in Jordan). Respondents in Jordan (33.5%) and Lebanon (40.1%) reported difficulties obtaining child vaccinations. Our estimated immunization rates were lower than expected and raise serious concerns about gaps in vaccine coverage among Syrian refugees. Although our estimates likely under-represent true coverage, given the additional benefit of campaigns (not captured in our surveys), there is a clear need to increase awareness, accessibility, and uptake of immunization services. Current methods to measure vaccine coverage in refugee and displaced populations have limitations. To better understand health needs in such groups, we need research on: validity of recall methods, links between campaigns and routine immunization programs, and improved sampling of hard-to-reach populations. PMID:28805672

Patterns of generic extinction in the fossil record

NASA Technical Reports Server (NTRS)

Raup, D. M.; Boyajian, G. E.

1988-01-01

Analysis of the stratigraphic records of 19,897 fossil genera indicates that most classes and orders show largely congruent rises and falls in extinction intensity throughout the Phanerozoic. Even an ecologically homogeneous sample of reef genera shows the same basic extinction profile. The most likely explanation for the congruence is that extinction is physically rather than biologically driven and that it is dominated by the effects of geographically widespread environmental perturbations influencing most habitats. Significant departures from the congruence are uncommon but important because they indicate physiological or habitat selectivity. The similarity of the extinction records of reef organisms and the marine biota as a whole confirms that reefs and other faunas are responding to the same history of environmental stress.

Biomarkers for Allergen Immunotherapy: A "Panoromic" View.

PubMed

Moingeon, Philippe

2016-02-01

Biomarkers (BMKs) are biological parameters that can be measured to predict or monitor disease severity or treatment efficacy. The induction of regulatory dendritic cells (DCs) concomitantly with a downregulation of proallergic DC2s (ie, DCs supporting the differentiation of T-helper lymphocyte type 2 cells) in the blood of patients allergic to grass pollen has been correlated with the early onset of allergen immunotherapy efficacy. The combined use of omics technologies to compare biological samples from clinical responders and nonresponders is being implemented in the context of nonhypothesis-driven approaches. Such comprehensive "panoromic" strategies help identify completely novel candidate BMKs, to be subsequently validated as companion diagnostics in large-scale clinical trials. Copyright © 2016 Elsevier Inc. All rights reserved.

Experiences of Violence Among Transgender Women in Puerto Rico: An Underestimated Problem.

PubMed

Rodríguez-Madera, Sheilla L; Padilla, Mark; Varas-Díaz, Nelson; Neilands, Torsten; Vasques Guzzi, Ana C; Florenciani, Ericka J; Ramos-Pibernus, Alíxida

2017-01-01

Violence is a public health concern faced on a daily basis by transgender women. Literature has documented how it adversely affects quality of life and health and in some instances leads to homicide. Considering the lack of research documenting the experiences of violence among transgender women, the objective of this article was to explore manifestations of violence among this population in Puerto Rico. The data presented in this article are part of a larger study on transgender/transsexual health in Puerto Rico. For the purpose of this article we focus on the quantitative data analysis. Participants (N = 59 transgender women) were recruited via respondent driven sampling. Implications and specific recommendations are discussed in light of these findings.

Experiences of Violence Among Transgender Women in Puerto Rico: An Underestimated Problem

PubMed Central

Rodríguez-Madera, Sheilla L.; Padilla, Mark; Varas-Díaz, Nelson; Neilands, Torsten; Vasques Guzzi, Ana C.; Florenciani, Ericka J.; Ramos-Pibernus, Alíxida

2017-01-01

Violence is a public health concern faced on a daily basis by transgender women. Literature has documented how it adversely affects quality of life and health and in some instances leads to homicide. Considering the lack of research documenting the experiences of violence among transgender women, the objective of this article was to explore manifestations of violence among this population in Puerto Rico. The data presented in this article are part of a larger study on transgender/transsexual health in Puerto Rico. For the purpose of this article we focus on the quantitative data analysis. Participants (N = 59 transgender women) were recruited via respondent driven sampling. Implications and specific recommendations are discussed in light of these findings. PMID:27054395

Scenario and modelling uncertainty in global mean temperature change derived from emission driven Global Climate Models

NASA Astrophysics Data System (ADS)

Booth, B. B. B.; Bernie, D.; McNeall, D.; Hawkins, E.; Caesar, J.; Boulton, C.; Friedlingstein, P.; Sexton, D.

2012-09-01

We compare future changes in global mean temperature in response to different future scenarios which, for the first time, arise from emission driven rather than concentration driven perturbed parameter ensemble of a Global Climate Model (GCM). These new GCM simulations sample uncertainties in atmospheric feedbacks, land carbon cycle, ocean physics and aerosol sulphur cycle processes. We find broader ranges of projected temperature responses arising when considering emission rather than concentration driven simulations (with 10-90 percentile ranges of 1.7 K for the aggressive mitigation scenario up to 3.9 K for the high end business as usual scenario). A small minority of simulations resulting from combinations of strong atmospheric feedbacks and carbon cycle responses show temperature increases in excess of 9 degrees (RCP8.5) and even under aggressive mitigation (RCP2.6) temperatures in excess of 4 K. While the simulations point to much larger temperature ranges for emission driven experiments, they do not change existing expectations (based on previous concentration driven experiments) on the timescale that different sources of uncertainty are important. The new simulations sample a range of future atmospheric concentrations for each emission scenario. Both in case of SRES A1B and the Representative Concentration Pathways (RCPs), the concentration pathways used to drive GCM ensembles lies towards the lower end of our simulated distribution. This design decision (a legecy of previous assessments) is likely to lead concentration driven experiments to under-sample strong feedback responses in concentration driven projections. Our ensemble of emission driven simulations span the global temperature response of other multi-model frameworks except at the low end, where combinations of low climate sensitivity and low carbon cycle feedbacks lead to responses outside our ensemble range. The ensemble simulates a number of high end responses which lie above the CMIP5 carbon cycle range. These high end simulations can be linked to sampling a number of stronger carbon cycle feedbacks and to sampling climate sensitivities above 4.5 K. This latter aspect highlights the priority in identifying real world climate sensitivity constraints which, if achieved, would lead to reductions on the uppper bound of projected global mean temperature change. The ensembles of simulations presented here provides a framework to explore relationships between present day observables and future changes while the large spread of future projected changes, highlights the ongoing need for such work.

The Sociospatial Network: Risk and the Role of Place in the Transmission of Infectious Diseases.

PubMed

Logan, James J; Jolly, Ann M; Blanford, Justine I

2016-01-01

Control of sexually transmitted infections and blood-borne pathogens is challenging due to their presence in groups exhibiting complex social interactions. In particular, sharing injection drug use equipment and selling sex (prostitution) puts people at high risk. Previous work examining the involvement of risk behaviours in social networks has suggested that social and geographic distance of persons within a group contributes to these pathogens' endemicity. In this study, we examine the role of place in the connectedness of street people, selected by respondent driven sampling, in the transmission of blood-borne and sexually transmitted pathogens. A sample of 600 injection drug users, men who have sex with men, street youth and homeless people were recruited in Winnipeg, Canada from January to December, 2009. The residences of participants and those of their social connections were linked to each other and to locations where they engaged in risk activity. Survey responses identified 101 unique sites where respondents participated in injection drug use or sex transactions. Risk sites and respondents' residences were geocoded, with residence representing the individuals. The sociospatial network and estimations of geographic areas most likely to be frequented were mapped with network graphs and spatially using a Geographic Information System (GIS). The network with the most nodes connected 7.7% of respondents; consideration of the sociospatial network increased this to 49.7%. The mean distance between any two locations in the network was within 3.5 kilometres. Kernel density estimation revealed key activity spaces where the five largest networks overlapped. Here, the combination of spatial and social entities in network analysis defines the overlap of vulnerable populations in risk space, over and above the person to person links. Implications of this work are far reaching, not just for understanding transmission dynamics of sexually transmitted infections by identifying activity "hotspots" and their intersection with each social network, but also for the spread of other diseases (e.g. tuberculosis) and targeting prevention services.

Can Burt's Theory of Structural Holes be Applied to Study Social Support Among Mid-Age Female Sex Workers? A Multi-Site Egocentric Network Study in China.

PubMed

Liu, Hongjie

2017-12-01

The epidemic of HIV/AIDS continues to spread among older adults and mid-age female sex workers (FSWs) over 35 years old. We used egocentric network data collected from three study sites in China to examine the applicability of Burt's Theory of Social Holes to study social support among mid-age FSWs. Using respondent-driven sampling, 1245 eligible mid-age FSWs were interviewed. Network structural holes were measured by network constraint and effective size. Three types of social networks were identified: family networks, workplace networks, and non-FSW networks. A larger effective size was significantly associated with a higher level of social support [regression coefficient (β) 5.43-10.59] across the three study samples. In contrast, a greater constraint was significantly associated with a lower level of social support (β -9.33 to -66.76). This study documents the applicability of the Theory of Structural Holes in studying network support among marginalized populations, such as FSWs.

Male and Female Stimulant Use Among Rural Kentuckians: The Contribution of Spirituality and Religiosity

PubMed Central

Staton-Tindall, Michele; Oser, Carrie B.; Duvall, Jamieson L.; Havens, Jennifer R.; Webster, J. Matthew; Leukefeld, Carl; Booth, Brenda M.

2017-01-01

This study describes gender-specific patterns of drug use among active rural stimulant users and examines religiosity and spirituality as factors that may be related to stimulant use among males and females. The study includes a sample of 225 active rural stimulant users from Kentucky who were recruited using respondent driven sampling and completed face-to-face interviews. Findings suggest gender specific patterns among active rural stimulant users, with females reporting more amphetamine use. In addition, bivariate findings indicate that there is an inverse relationship between spirituality, religiosity, and stimulant use (specifically methamphetamine and amphetamine use), particularly for males. However, when further examining this relationship in multivariate models controlling for age and race, few significant findings were noted for spirituality and religiosity in predicting gender-specific stimulant use patterns. These findings suggest that treatment interventions that incorporate spirituality and religiosity should not only be gender specific, but should also target clients differentially. Findings on the degree of reported spirituality and religiosity also suggest that religious and/or faithbased organizations could be utilized for drug use interventions for rural stimulant users. PMID:29104311

HIV Prevalence and Risk Factors Among Male Foreign Migrants in Cape Town, South Africa

PubMed Central

Townsend, Loraine; Zembe, Yanga; Cheyip, Mireille; Guttmacher, Sally; Carter, Rebecca; Mathews, Cathy

2018-01-01

While migration has been shown to be a risk factor for HIV, variation in HIV prevalence by subgroups of migrants needs further exploration. This paper documents the HIV prevalence and key characteristics among male foreign migrants in Cape Town, South Africa and the effectiveness of respondent-driven sampling (RDS) to recruit this population. Participants in this cross-sectional study completed a behavioral risk-factor questionnaire and provided a dried blood sample for HIV analysis. Overall HIV prevalence was estimated to be 8.7 % (CI 5.4–11.8) but varied dramatically by country of origin. After adjusting for country of origin, HIV sero-positivity was positively associated with older age (p = 0.001), completing high school (p = 0.025), not having enough money for food (p = 0.036), alcohol use (p = 0.049), and engaging in transactional sex (p = 0.022). RDS was successful in recruiting foreign migrant men. A better understanding of the timing of HIV acquisition is needed to design targeted interventions for migrant men. PMID:24781639

Substance Use over the Military-Veteran Life Course: An Analysis of a Sample of OEF/OIF Veterans Returning to Low-Income Predominately Minority Communities

PubMed Central

Golub, Andrew; Bennett, Alex S.

2013-01-01

This paper presents an overview of substance use patterns of recent veterans returning to low-income predominately minority communities over four periods of the military-veteran career. Respondent driven sampling (RDS) was used so that unbiased estimates could be obtained for the characteristics of the target population. The majority of participants had used marijuana but no other illegal drugs. In the military, marijuana use was substantially lower and alcohol was the drug of choice; the majority were binge drinkers and nearly half were heavy drinkers. While deployed, alcohol and marijuana use were both lower, though some participants (6%) initiated the misuse of prescription painkillers. After separating from the military and returning to civilian life, heavy drinking was much lower, marijuana use increased, and some veterans misused prescription painkillers (7%). Further research based on these data will examine these distinct periods of substance use, contexts of use, related substance and mental health problems, treatment use and avoidance, and civilian reintegration. PMID:23932708

HIV Research with Men who Have Sex with Men (MSM): Advantages and Challenges of Different Methods for Most Appropriately Targeting a Key Population.

PubMed

Gama, Ana; Martins, Maria O; Dias, Sónia

2017-01-01

The difficulty in accessing hard-to-reach populations as men who have sex with men presents a dilemma for HIV surveillance as their omission from surveillance systems leaves significant gaps in our understanding of HIV/AIDS epidemics. Several methods for recruiting difficult-to-access populations and collecting data on trends of HIV prevalence and behavioural factors for surveillance and research purposes have emerged. This paper aims to critically review different sampling approaches, from chain-referral and venue-based to respondent-driven, time-location and internet sampling methods, focusing on its main advantages and challenges for conducting HIV research among key populations, such as men who have sex with men. The benefits of using these approaches to recruit participants must be weighed against privacy concerns inherent in any social situation or health condition. Nevertheless, the methods discussed in this paper represent some of the best efforts to effectively reach most-at-risk subgroups of men who have sex with men, contributing to obtain unbiased trends of HIV prevalence and HIV-related risk behaviours among this population group.

Fluorescent blue lights, injecting drug use and related health risk in public conveniences: findings from a qualitative study of micro-injecting environments.

PubMed

Parkin, Stephen; Coomber, Ross

2010-07-01

This paper presents findings relating to injecting drug users' experiences and opinions of public toilets illuminated with fluorescent blue lights and presents an empirical assessment of the intended deterrent effect of such installations. Data analysis identified that blue lights deterred less than half the sample interviewed. Furthermore over half (18/31) of the sample were prepared to inject in conditions specifically designed to deter injecting practice. Of these, 11 respondents were completely undeterred and 7 individuals were only partially deterred by blue light environments. These findings are discussed within the interpretative frameworks of Pierre Bourdieu's theory of habitus and symbolic violence. The authors conclude that fluorescent blue lights contribute towards the development of situated resistance by injecting drug users within a public injecting habitus; a resistance that produces and reproduces drug-related harm and is a behaviour that opposes the symbolic violence of harm reduction intervention. The paper concludes with suggestions for theory-driven practical intervention that may seek to disrupt the harmful elements of the public injecting habitus. 2010 Elsevier Ltd. All rights reserved.

Incidence of Near-Death and Intense Spiritual Experiences in an Intergenerational Sample: An Interpretation.

ERIC Educational Resources Information Center

Thomas, L. Eugene; And Others

1982-01-01

Determined incidence of near-death and intense spiritual experiences for a sample of 305 persons from ages 17-85. Found incidence of near-death reports did not vary significantly by age of respondents, but elderly respondents were significantly less likely to report intense spiritual experiences. (Author)

Gas-driven pump for ground-water samples

USGS Publications Warehouse

Signor, Donald C.

1978-01-01

Observation wells installed for artificial-recharge research and other wells used in different ground-water programs are frequently cased with small-diameter steel pipe. To obtain samples from these small-diameter wells in order to monitor water quality, and to calibrate solute-transport models, a small-diameter pump with unique operating characteristics is required that causes a minimum alternation of samples during field sampling. A small-diameter gas-driven pump was designed and built to obtain water samples from wells of two-inch diameter or larger. The pump is a double-piston type with the following characteristics: (1) The water sample is isolated from the operating gas, (2) no source of electricity is ncessary, (3) operation is continuous, (4) use of compressed gas is efficient, and (5) operation is reliable over extended periods of time. Principles of operation, actual operation techniques, gas-use analyses and operating experience are described. Complete working drawings and a component list are included. Recent modifications and pump construction for high-pressure applications also are described. (Woodard-USGS)

Replicating studies in which samples of participants respond to samples of stimuli.

PubMed

Westfall, Jacob; Judd, Charles M; Kenny, David A

2015-05-01

In a direct replication, the typical goal is to reproduce a prior experimental result with a new but comparable sample of participants in a high-powered replication study. Often in psychology, the research to be replicated involves a sample of participants responding to a sample of stimuli. In replicating such studies, we argue that the same criteria should be used in sampling stimuli as are used in sampling participants. Namely, a new but comparable sample of stimuli should be used to ensure that the original results are not due to idiosyncrasies of the original stimulus sample, and the stimulus sample must often be enlarged to ensure high statistical power. In support of the latter point, we discuss the fact that in experiments involving samples of stimuli, statistical power typically does not approach 1 as the number of participants goes to infinity. As an example of the importance of sampling new stimuli, we discuss the bygone literature on the risky shift phenomenon, which was almost entirely based on a single stimulus sample that was later discovered to be highly unrepresentative. We discuss the use of both resampled and expanded stimulus sets, that is, stimulus samples that include the original stimuli plus new stimuli. © The Author(s) 2015.

Blood sample collection and patient identification demand improvement: a questionnaire study of preanalytical practices in hospital wards and laboratories.

PubMed

Wallin, Olof; Söderberg, Johan; Van Guelpen, Bethany; Stenlund, Hans; Grankvist, Kjell; Brulin, Christine

2010-09-01

Scand J Caring Sci; 2010; 24; 581-591 
 Blood sample collection and patient identification demand improvement: a questionnaire study of preanalytical practices in hospital wards and laboratories   Most errors in venous blood testing result from human mistakes occurring before the sample reach the laboratory.   To survey venous blood sampling (VBS) practices in hospital wards and to compare practices with hospital laboratories.   Staff in two hospitals (all wards) and two hospital laboratories (314 respondents, response rate 94%), completed a questionnaire addressing issues relevant to the collection of venous blood samples for clinical chemistry testing.   The findings suggest that instructions for patient identification and the collection of venous blood samples were not always followed. For example, 79% of the respondents reported the undesirable practice (UDP) of not always using wristbands for patient identification. Similarly, 87% of the respondents noted the UDP of removing venous stasis after the sampling is finished. Compared with the ward staff, a significantly higher proportion of the laboratory staff reported desirable practices regarding the collection of venous blood samples. Neither education nor the existence of established sampling routines was clearly associated with VBS practices among the ward staff.   The results of this study, the first of its kind, suggest that a clinically important risk of error is associated with VBS in the surveyed wards. Most important is the risk of misidentification of patients. Quality improvement of blood sample collection is clearly needed, particularly in hospital wards. © 2009 The Authors. Journal compilation © 2009 Nordic College of Caring Science.

AC Current Driven Dynamic Vortex State in YBa2Cu3O7-x (Postprint)

DTIC Science & Technology

2012-02-01

coexisting steady states of driven vortex motion with different characteristics: a quasi-static disordered glassy state in the sample interior and a...coexisting, vortex, plastic, dynamic, calculations, disordered , hysteretic, model, films, edges 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...characteris- tics: a quasi-static disordered glassy state in the sample interior and a dynamic state of plastic motion near the edges. Finite- element

An accessible micro-capillary electrophoresis device using surface-tension-driven flow

PubMed Central

Mohanty, Swomitra K.; Warrick, Jay; Gorski, Jack; Beebe, David J.

2010-01-01

We present a rapidly fabricated micro-capillary electrophoresis chip that utilizes surface-tension-driven flow for sample injection and extraction of DNA. Surface-tension-driven flow (i.e. passive pumping) injects a fixed volume of sample that can be predicted mathematically. Passive pumping eliminates the need for tubing, valves, syringe pumps, and other equipment typically needed for interfacing with microelectrophoresis chips. This method requires a standard micropipette to load samples before separation, and remove the resulting bands after analysis. The device was made using liquid phase photopolymerization to rapidly fabricate the chip without the need of special equipment typically associated with the construction of microelectrophoresis chips (e.g. cleanroom). Batch fabrication time for the device presented here was 1.5 h including channel coating time to suppress electroosmotic flow. Devices were constructed out of poly-isobornyl acrylate and glass. A standard microscope with a UV source was used for sample detection. Separations were demonstrated using Promega BenchTop 100 bp ladder in hydroxyl ethyl cellulose (HEC) and oligonucleotides of 91 and 118 bp were used to characterize sample injection and extraction of DNA bands. The end result was an inexpensive micro-capillary electrophoresis device that uses tools (e.g. micropipette, electrophoretic power supplies, and microscopes) already present in most labs for sample manipulation and detection, making it more accessible for potential end users. PMID:19425002

Driven-dissipative quantum Monte Carlo method for open quantum systems

NASA Astrophysics Data System (ADS)

Nagy, Alexandra; Savona, Vincenzo

2018-05-01

We develop a real-time full configuration-interaction quantum Monte Carlo approach to model driven-dissipative open quantum systems with Markovian system-bath coupling. The method enables stochastic sampling of the Liouville-von Neumann time evolution of the density matrix thanks to a massively parallel algorithm, thus providing estimates of observables on the nonequilibrium steady state. We present the underlying theory and introduce an initiator technique and importance sampling to reduce the statistical error. Finally, we demonstrate the efficiency of our approach by applying it to the driven-dissipative two-dimensional X Y Z spin-1/2 model on a lattice.

NHEXAS PHASE I MARYLAND STUDY--PESTICIDES IN DERMAL WIPES ANALYTICAL RESULTS

EPA Science Inventory

The Pesticides in Dermal Wipe Samples data set contains analytical results for measurements of up to 8 pesticides in 40 dermal wipe samples over 40 households. Each sample was collected from the primary respondent within each household. The sampling period occurred on the last ...

NHEXAS PHASE I MARYLAND STUDY--PESTICIDES IN BLOOD ANALYTICAL RESULTS

EPA Science Inventory

The Pesticides in Blood Serum data set contains analytical results for measurements of up to 17 pesticides in 358 blood samples over 79 households. Each sample was collected via a venous sample from the primary respondent within each household by a phlebotomist. Samples were ge...

Assessing Generative Braille Responding Following Training in a Matching-to-Sample Format

ERIC Educational Resources Information Center

Putnam, Brittany C.; Tiger, Jeffrey H.

2016-01-01

We evaluated the effects of teaching sighted college students to select printed text letters given a braille sample stimulus in a matching-to-sample (MTS) format on the emergence of untrained (a) construction of print characters given braille samples, (b) construction of braille characters given print samples, (c) transcription of print characters…

A randomized controlled trial in non-responders from Newcastle upon Tyne invited to return a self-sample for Human Papillomavirus testing versus repeat invitation for cervical screening.

PubMed

Cadman, Louise; Wilkes, Scott; Mansour, Diana; Austin, Janet; Ashdown-Barr, Lesley; Edwards, Rob; Kleeman, Michelle; Szarewski, Anne

2015-03-01

Non-attenders for cervical screening are at increased risk of cervical cancer. Studies offering self-sampling for high-risk Human Papillomavirus (HrHPV) testing have shown greater uptake than sending another invitation for cytology. To explore whether uptake would increase in a less diverse, more stable population than the previous English study, which demonstrated a lower response rate than other studies. The primary objective was whether non-attenders were more likely to respond to a postal invitation, including kit, to collect a self-sample compared with a further invitation for cytology screening. The secondary objective was whether women with an abnormal result would attend for follow-up. 6000 non-attenders for screening in this pragmatic, randomized (1:1) controlled trial in Newcastle-upon-Tyne were sent an HPV self-sample kit (intervention) or a further invitation for cytology screening (comparator). 411(13%) responded to the intervention, returning a self-sample (247(8%)) or attending for cytology (164(5%)), compared with 183(6%) attending for cytology, relative risk 2.25 (95% CI 1.90-2.65) (comparator arm). Of those testing hrHPV positive (32(13%)), 19(59%) subsequently attended cytology screening. Of those in the intervention group who attended for cytology screening without returning an hrHPV self-sample (n = 164), 5% (n = 8) were referred for colposcopy - all attended. In the comparator group eight of the nine referred for colposcopy attended. Persistent non-responders to invitations for cervical screening are significantly more likely to respond to a postal invitation to return a self-collected sample for HPV testing than a further invitation for cytology screening. However, just over half followed up on this positive HPV result. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Barriers and missed opportunities to HIV testing among injection drug users in two Mexico--US border cities.

PubMed

Moyer, Laura B; Brouwer, Kimberley C; Brodine, Stephanie K; Ramos, Rebeca; Lozada, Remedios; Cruz, Michelle Firestone; Magis-Rodriguez, Carlos; Strathdee, Steffanie A

2008-01-01

Despite increasing HIV prevalence in cities along the Mexico--US border, HIV testing among high-risk populations remains low. We sought to identify barriers associated with HIV testing among injection drug users (IDUs) in Tijuana and Ciudad Juarez, the two largest Mexican border cities located across from San Diego, California and El Paso, Texas, respectively. In 2005, 222 IDUs in Tijuana and 205 IDUs in Ciudad Juarez were recruited by respondent-driven sampling and administered a questionnaire to collect socio-demographic, behavioural and HIV testing history data. Blood samples were provided for serological testing of HIV, hepatitis C virus (HCV) and syphilis. Only 38% and 30% of respondents in Tijuana and Ciudad Juarez, respectively, had ever had an HIV test. The factors independently associated with never having been tested for HIV differed between the two sites, except for lack of knowledge on HIV transmission, which was independently associated in both locales. Importantly, 65% of those who had never been tested for HIV in both cities experienced at least one missed opportunity for voluntary testing, including medical visits, drug treatment and spending time in jail. Among this high-risk IDU population we found HIV testing to be low, with voluntary testing in public and private settings utilised inadequately. These findings underscore the need to expand voluntary HIV education and testing and to integrate it into services and locales frequented by IDUs in these Mexico--US border cities.

Knowledge-guided golf course detection using a convolutional neural network fine-tuned on temporally augmented data

NASA Astrophysics Data System (ADS)

Chen, Jingbo; Wang, Chengyi; Yue, Anzhi; Chen, Jiansheng; He, Dongxu; Zhang, Xiuyan

2017-10-01

The tremendous success of deep learning models such as convolutional neural networks (CNNs) in computer vision provides a method for similar problems in the field of remote sensing. Although research on repurposing pretrained CNN to remote sensing tasks is emerging, the scarcity of labeled samples and the complexity of remote sensing imagery still pose challenges. We developed a knowledge-guided golf course detection approach using a CNN fine-tuned on temporally augmented data. The proposed approach is a combination of knowledge-driven region proposal, data-driven detection based on CNN, and knowledge-driven postprocessing. To confront data complexity, knowledge-derived cooccurrence, composition, and area-based rules are applied sequentially to propose candidate golf regions. To confront sample scarcity, we employed data augmentation in the temporal domain, which extracts samples from multitemporal images. The augmented samples were then used to fine-tune a pretrained CNN for golf detection. Finally, commission error was further suppressed by postprocessing. Experiments conducted on GF-1 imagery prove the effectiveness of the proposed approach.

NHEXAS PHASE I MARYLAND STUDY--METALS IN DERMAL WIPES ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Dermal Wipe Samples data set contains analytical results for measurements of up to 4 metals in 343 dermal wipe samples over 80 households. Each sample was collected from the primary respondent within each household. The sampling period occurred on the first day of...

NHEXAS PHASE I ARIZONA STUDY--METALS IN BLOOD ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Blood data set contains analytical results for measurements of up to 2 metals in 165 blood samples over 165 households. Each sample was collected as a venous sample from the primary respondent within each household during Stage III of the NHEXAS study. The samples...

NHEXAS PHASE I MARYLAND STUDY--METALS IN BLOOD ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Blood data set contains analytical results for measurements of up to 2 metals in 374 blood samples over 80 households. Each sample was collected via a venous sample from the primary respondent within each household by a phlebotomist. Samples were generally drawn o...

Identifying Factors Associated with Risk Assessment Competencies of Public Health Emergency Responders.

PubMed

Hao, Jiejing; Ren, Jiaojiao; Wu, Qunhong; Hao, Yanhua; Sun, Hong; Ning, Ning; Ding, Ding

2017-06-04

This study aimed to better understand the current situation of risk assessment and identify the factors associated with competence of emergency responders in public health risk assessment. The participants were selected by a multi-stage, stratified cluster sampling method in Heilongjiang Centers for Disease Control and Prevention (CDC). The questionnaires that measured their perceptions on risk assessment competences were administered through the face-to-face survey. A final sample of 1889 staff was obtained. Of this sample, 78.6% of respondents rated their own risk assessment competences as "relatively low", contrasting with 21.4% rated as "relatively high". Most of the respondents (62.7%) did not participate in any risk assessment work. Only 13.7% and 42.7% of respondents reported participating in risk assessment training and were familiar with risk assessment tools. There existed statistical significance between risk assessment-related characteristics of respondents and their self-rated competences scores. Financial support from the government and administrative attention were regarded as the important factors contributing to risk assessment competences of CDC responders. Higher attention should be given to risk assessment training and enhancing the availability of surveillance data. Continuous efforts should be made to remove the financial and technical obstacles to improve the competences of risk assessment for public health emergency responders.

Identifying Factors Associated with Risk Assessment Competencies of Public Health Emergency Responders

PubMed Central

Hao, Jiejing; Ren, Jiaojiao; Wu, Qunhong; Hao, Yanhua; Sun, Hong; Ning, Ning; Ding, Ding

2017-01-01

This study aimed to better understand the current situation of risk assessment and identify the factors associated with competence of emergency responders in public health risk assessment. The participants were selected by a multi-stage, stratified cluster sampling method in Heilongjiang Centers for Disease Control and Prevention (CDC). The questionnaires that measured their perceptions on risk assessment competences were administered through the face-to-face survey. A final sample of 1889 staff was obtained. Of this sample, 78.6% of respondents rated their own risk assessment competences as “relatively low”, contrasting with 21.4% rated as “relatively high”. Most of the respondents (62.7%) did not participate in any risk assessment work. Only 13.7% and 42.7% of respondents reported participating in risk assessment training and were familiar with risk assessment tools. There existed statistical significance between risk assessment-related characteristics of respondents and their self-rated competences scores. Financial support from the government and administrative attention were regarded as the important factors contributing to risk assessment competences of CDC responders. Higher attention should be given to risk assessment training and enhancing the availability of surveillance data. Continuous efforts should be made to remove the financial and technical obstacles to improve the competences of risk assessment for public health emergency responders. PMID:28587226

Still Struggling: Characteristics of Youth with OCD Who Are Partial Responders to Medication Treatment

ERIC Educational Resources Information Center

Freeman, J.; Sapyta, J.; Garcia, A.; Fitzgerald, D.; Khanna, M.; Choate-Summers, M.; Moore, P.; Chrisman, A.; Haff, N.; Naeem, A.; March, J.; Franklin, M.

2011-01-01

The primary aim of this paper is to examine the characteristics of a large sample of youth with OCD who are partial responders (i.e., still have clinically significant symptoms) to serotonin reuptake inhibitor (SRI) medication. The sample will be described with regard to: demographics, treatment history, OCD symptoms/severity, family history and…

Maternal Labor Supply and Children's Cognitive Development. NBER Working Paper Series.

ERIC Educational Resources Information Center

Blau, Francine D.; Grossberg, Adam J.

This study used a sample of 3- and 4-year-old children of female respondents from the 1986 National Longitudinal Surveys Youth Cohort to analyze the relationship between maternal labor supply and children's cognitive development. Respondents were 21 to 29 years old in 1986. Thus, the sample consisted of children of relatively young mothers.…

Gender Differences in Participation in Elective Mathematics of Senior Secondary School Students in Ghana

ERIC Educational Resources Information Center

Baah-Korang, Kwame; Gyan, Emmanuel; McCarthy, Paul; McCarthy, Peter

2015-01-01

This paper aims at contributing to the body of knowledge that exists in the area of differences in participation in elective mathematics, between boys and girls in Secondary Schools in Ghana. A sample of 738 respondents from five Secondary Schools was purposively selected using purposive sampling technique. All the respondents were final year…

Alcohol- and Drug-Involved Driving in the United States: Methodology for the 2007 National Roadside Survey

PubMed Central

Lacey, John H.; Kelley-Baker, Tara; Voas, Robert B.; Romano, Eduardo; Furr-Holden, C. Debra; Torres, Pedro; Berning, Amy

2013-01-01

This article describes the methodology used in the 2007 U.S. National Roadside Survey to estimate the prevalence of alcohol- and drug-impaired driving and alcohol- and drug-involved driving. This study involved randomly stopping drivers at 300 locations across the 48 continental U.S. states at sites selected through a stratified random sampling procedure. Data were collected during a 2-hour Friday daytime session at 60 locations and during 2-hour nighttime weekend periods at 240 locations. Both self-report and biological measures were taken. Biological measures included breath alcohol measurements from 9,413 respondents, oral fluid samples from 7,719 respondents, and blood samples from 3,276 respondents. PMID:21997324

Convenience samples and caregiving research: how generalizable are the findings?

PubMed

Pruchno, Rachel A; Brill, Jonathan E; Shands, Yvonne; Gordon, Judith R; Genderson, Maureen Wilson; Rose, Miriam; Cartwright, Francine

2008-12-01

We contrast characteristics of respondents recruited using convenience strategies with those of respondents recruited by random digit dial (RDD) methods. We compare sample variances, means, and interrelationships among variables generated from the convenience and RDD samples. Women aged 50 to 64 who work full time and provide care to a community-dwelling older person were recruited using either RDD (N = 55) or convenience methods (N = 87). Telephone interviews were conducted using reliable, valid measures of demographics, characteristics of the care recipient, help provided to the care recipient, evaluations of caregiver-care recipient relationship, and outcomes common to caregiving research. Convenience and RDD samples had similar variances on 68.4% of the examined variables. We found significant mean differences for 63% of the variables examined. Bivariate correlations suggest that one would reach different conclusions using the convenience and RDD sample data sets. Researchers should use convenience samples cautiously, as they may have limited generalizability.

Multi-source recruitment strategies for advancing addiction recovery research beyond treated samples

PubMed Central

Subbaraman, Meenakshi Sabina; Laudet, Alexandre B.; Ritter, Lois A.; Stunz, Aina; Kaskutas, Lee Ann

2014-01-01

Background The lack of established sampling frames makes reaching individuals in recovery from substance problems difficult. Although general population studies are most generalizable, the low prevalence of individuals in recovery makes this strategy costly and inefficient. Though more efficient, treatment samples are biased. Aims To describe multi-source recruitment for capturing participants from heterogeneous pathways to recovery; assess which sources produced the most respondents within subgroups; and compare treatment and non-treatment samples to address generalizability. Results Family/friends, Craigslist, social media and non-12-step groups produced the most respondents from hard-to-reach groups, such as racial minorities and treatment-naïve individuals. Recovery organizations yielded twice as many African-Americans and more rural dwellers, while social media yielded twice as many young people than other sources. Treatment samples had proportionally fewer females and older individuals compared to non-treated samples. Conclusions Future research on recovery should utilize previously neglected recruiting strategies to maximize the representativeness of samples. PMID:26166909

Cream of the Crop: Clinical Representativeness of Eligible and Ineligible Cannabis Users in Research.

PubMed

Rosen, Alexis S; Sodos, Louise M; Hirst, Rayna B; Vaughn, Dylan; Lorkiewicz, Sara A

2018-03-06

Experts have recommended criteria (Gonzalez et al., 2002) for recruiting pure chronic cannabis users (i.e., those without polysubstance use or psychiatric illness) when evaluating cannabis' non-acute effects on cognition. We sought to demonstrate the implications of using such criteria by examining characteristics of respondents who completed an eligibility screening for a parent study evaluating the cognitive effects of chronic cannabis use. Over a 3-year, 8-month period, 612 respondents from the community completed an eligibility screening based on recommendations in the cannabis literature. Using independent samples t-tests and chi-square tests, we examined whether qualified/eligible respondents (n = 219) differed from non-qualified/ineligible respondents (n = 393). Compared to ineligible cannabis users, eligible cannabis-using respondents were significantly younger, used cannabis more frequently, used alcohol less frequently, and were less likely to have a history of other drug use, a psychiatric diagnosis, or to have used psychiatric medication. Conclusions/Importance: Our findings indicate that eligible/pure cannabis users are not representative of typical cannabis users in the general community (i.e., ineligible users with polysubstance use and/or psychiatric diagnoses) who ultimately comprised the majority of our cannabis-using sample (65.2%). Thus, typical cannabis users may be more accurately characterized as polysubstance users, posing a number of challenges related to the generalizability of findings from studies utilizing pure samples of cannabis users. Recruiting samples of typical cannabis users will improve external validity in research. Furthermore, reporting comprehensive characteristics of such samples will enable consumers to gauge the applicability of study findings to populations of interest.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--METALS IN BLOOD ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Blood data set contains analytical results for measurements of up to 2 metals in 86 blood samples over 86 households. Each sample was collected as a venous sample from the primary respondent within each household. The samples consisted of two 3-mL tubes. The prim...

Understanding hospital meal experiences by means of participant-driven-photo-elicitation.

PubMed

Justesen, Lise; Mikkelsen, Bent E; Gyimóthy, Szilvia

2014-04-01

A patients' hospital meal experiences can be complex and often difficult to capture using traditional methods. This study investigated patients' hospital meal experiences using participant-driven-photo-elicitation (PDPE). PDPE invites respondents to photograph their daily lives and combines this with interviews, which can provide deeper insight into multisensory experiences beyond verbal or written discourse. The sample consisted of eight hospitalised patients. Patients completed a photo-essay of their hospital meal experience during a single day at a Danish hospital and afterwards participated in an open-ended interview. Two inductive analytical approaches were selected to assess the patients' reflections on their hospital meal experiences. First, the interview transcripts were analysed using the Semiotic Analysis approach using qualitative data analysis software NVivo 9. Second, the 91 produced photographs and the participants' engagement with the photographs were analysed by means of a Reflexive Content Analysis. The study found that PDPE is a research method that can be used for expanding the conceptualisation of hospital meal experiences, revealing the significance of the meal context, materiality and memories beyond food per se. Copyright © 2013 Elsevier Ltd. All rights reserved.

Scenario and modelling uncertainty in global mean temperature change derived from emission-driven global climate models

NASA Astrophysics Data System (ADS)

Booth, B. B. B.; Bernie, D.; McNeall, D.; Hawkins, E.; Caesar, J.; Boulton, C.; Friedlingstein, P.; Sexton, D. M. H.

2013-04-01

We compare future changes in global mean temperature in response to different future scenarios which, for the first time, arise from emission-driven rather than concentration-driven perturbed parameter ensemble of a global climate model (GCM). These new GCM simulations sample uncertainties in atmospheric feedbacks, land carbon cycle, ocean physics and aerosol sulphur cycle processes. We find broader ranges of projected temperature responses arising when considering emission rather than concentration-driven simulations (with 10-90th percentile ranges of 1.7 K for the aggressive mitigation scenario, up to 3.9 K for the high-end, business as usual scenario). A small minority of simulations resulting from combinations of strong atmospheric feedbacks and carbon cycle responses show temperature increases in excess of 9 K (RCP8.5) and even under aggressive mitigation (RCP2.6) temperatures in excess of 4 K. While the simulations point to much larger temperature ranges for emission-driven experiments, they do not change existing expectations (based on previous concentration-driven experiments) on the timescales over which different sources of uncertainty are important. The new simulations sample a range of future atmospheric concentrations for each emission scenario. Both in the case of SRES A1B and the Representative Concentration Pathways (RCPs), the concentration scenarios used to drive GCM ensembles, lies towards the lower end of our simulated distribution. This design decision (a legacy of previous assessments) is likely to lead concentration-driven experiments to under-sample strong feedback responses in future projections. Our ensemble of emission-driven simulations span the global temperature response of the CMIP5 emission-driven simulations, except at the low end. Combinations of low climate sensitivity and low carbon cycle feedbacks lead to a number of CMIP5 responses to lie below our ensemble range. The ensemble simulates a number of high-end responses which lie above the CMIP5 carbon cycle range. These high-end simulations can be linked to sampling a number of stronger carbon cycle feedbacks and to sampling climate sensitivities above 4.5 K. This latter aspect highlights the priority in identifying real-world climate-sensitivity constraints which, if achieved, would lead to reductions on the upper bound of projected global mean temperature change. The ensembles of simulations presented here provides a framework to explore relationships between present-day observables and future changes, while the large spread of future-projected changes highlights the ongoing need for such work.

Debt and foregone medical care.

PubMed

Kalousova, Lucie; Burgard, Sarah A

2013-06-01

Most American households carry debt, yet we have little understanding of how debt influences health behavior, especially health care seeking. We examined associations between foregone medical care and debt using a population-based sample of 914 southeastern Michigan residents surveyed in the wake of the late-2000s recession. Overall debt and ratios of debt to income and debt to assets were positively associated with foregoing medical or dental care in the past 12 months, even after adjusting for the poorer socioeconomic and health characteristics of those foregoing care and for respondents' household incomes and net worth. These overall associations were driven largely by credit card and medical debt, while housing debt and automobile and student loans were not associated with foregoing care. These results suggest that debt is an understudied aspect of health stratification.

Mediators of interpersonal violence and drug addiction severity among methamphetamine users in Cape Town, South Africa

PubMed Central

Hobkirk, Andréa L.; Watt, Melissa H.; Green, Kimberly T.; Beckham, Jean C.; Skinner, Donald; Meade, Christina S.

2014-01-01

South Africa has high rates of interpersonal violence and a rapidly growing methamphetamine epidemic. Previous research has linked experiences of interpersonal violence to higher rates of substance use, and identified mental health constructs as potential mediators of this association. The aim of this study was to examine the relationship between interpersonal violence and addiction severity among active methamphetamine users in Cape Town, South Africa, and to explore symptoms of posttraumatic stress disorder (PTSD) and substance use coping as mediators of this relationship. A community sample of 360 methamphetamine users was recruited through respondent driven sampling and surveyed on their experiences of violence, mental health, coping, and drug use and severity. A series of one-way ANOVAs were conducted to examine the relationship of self-reported interpersonal violence with drug addiction severity, and multiple mediation analyses were used to determine if PTSD symptoms and substance use coping mediated this relationship. The majority (87%) of the sample reported experiencing at least one instance of interpersonal violence in their lifetime, and the number of violent experiences was associated with increased drug addiction severity. PTSD and substance use coping were significant mediators of this association. Only the indirect effect of substance use coping remained significant for the female sample when the mediation model was conducted separately for men and women. The findings point to the need for integrated treatments that address drug use and PTSD for methamphetamine users in South Africa and highlight the importance of coping interventions for women. PMID:25479528

Mediators of interpersonal violence and drug addiction severity among methamphetamine users in Cape Town, South Africa.

PubMed

Hobkirk, Andréa L; Watt, Melissa H; Green, Kimberly T; Beckham, Jean C; Skinner, Donald; Meade, Christina S

2015-03-01

South Africa has high rates of interpersonal violence and a rapidly growing methamphetamine epidemic. Previous research has linked experiences of interpersonal violence to higher rates of substance use, and identified mental health constructs as potential mediators of this association. The aim of this study was to examine the relationship between interpersonal violence and addiction severity among active methamphetamine users in Cape Town, South Africa, and to explore symptoms of posttraumatic stress disorder (PTSD) and substance use coping as mediators of this relationship. A community sample of 360 methamphetamine users was recruited through respondent driven sampling and surveyed on their experiences of violence, mental health, coping, and drug use and severity. A series of one-way ANOVAs were conducted to examine the relationship of self-reported interpersonal violence with drug addiction severity, and multiple mediation analyses were used to determine if PTSD symptoms and substance use coping mediated this relationship. The majority (87%) of the sample reported experiencing at least one instance of interpersonal violence in their lifetime, and the number of violent experiences was associated with increased drug addiction severity. PTSD and substance use coping were significant mediators of this association. Only the indirect effect of substance use coping remained significant for the female sample when the mediation model was conducted separately for men and women. The findings point to the need for integrated treatments that address drug use and PTSD for methamphetamine users in South Africa and highlight the importance of coping interventions for women. Copyright © 2014 Elsevier Ltd. All rights reserved.

Difference in Risk Behaviors and STD Prevalence Between Street-Based and Establishment-Based FSWs in Guangdong Province, China

PubMed Central

Li, Yan; Lin, Peng; Fu, Xiaobing; Deng, Zhongming; Liu, Yongying; Huang, Guohua; Li, Jie; Tan, Yihe

2012-01-01

The major mode of HIV/AIDS transmission in China is now heterosexual activities, but risk for HIV and sexually transmitted diseases (STDs) may differ among different strata of female sex workers (FSWs). Respondent-driven sampling was used to recruit 320 FSWs in Guangdong Province, China. The respondents were interviewed using a structured questionnaire, and tested for HIV, syphilis, gonorrhea, and Chlamydia. The street-based FSWs had lower education levels, a higher proportion supporting their families, charged less for their services, and had engaged in commercial sex for a longer period of time than establishment-based FSWs. The proportion consistently using condoms with clients and with regular non-paying partners was also lower. The prevalence of syphilis, gonorrhea, and Chlamydia was higher among street-based sex workers. Being a street-based sex worker, having regular non-paying sex partners, and having non-regular non-paying partners were independent risk factors for inconsistent condom. Street-based FSWs had more risk behaviors than establishment-based FSWs, and should therefore be specifically targeted for HIV as well as STD intervention programs. PMID:22228068

Americans misperceive racial economic equality

PubMed Central

Kraus, Michael W.; Rucker, Julian M.; Richeson, Jennifer A.

2017-01-01

The present research documents the widespread misperception of race-based economic equality in the United States. Across four studies (n = 1,377) sampling White and Black Americans from the top and bottom of the national income distribution, participants overestimated progress toward Black–White economic equality, largely driven by estimates of greater current equality than actually exists according to national statistics. Overestimates of current levels of racial economic equality, on average, outstripped reality by roughly 25% and were predicted by greater belief in a just world and social network racial diversity (among Black participants). Whereas high-income White respondents tended to overestimate racial economic equality in the past, Black respondents, on average, underestimated the degree of past racial economic equality. Two follow-up experiments further revealed that making societal racial discrimination salient increased the accuracy of Whites’ estimates of Black–White economic equality, whereas encouraging Whites to anchor their estimates on their own circumstances increased their tendency to overestimate current racial economic equality. Overall, these findings suggest a profound misperception of and unfounded optimism regarding societal race-based economic equality—a misperception that is likely to have any number of important policy implications. PMID:28923915

Americans misperceive racial economic equality.

PubMed

Kraus, Michael W; Rucker, Julian M; Richeson, Jennifer A

2017-09-26

The present research documents the widespread misperception of race-based economic equality in the United States. Across four studies ( n = 1,377) sampling White and Black Americans from the top and bottom of the national income distribution, participants overestimated progress toward Black-White economic equality, largely driven by estimates of greater current equality than actually exists according to national statistics. Overestimates of current levels of racial economic equality, on average, outstripped reality by roughly 25% and were predicted by greater belief in a just world and social network racial diversity (among Black participants). Whereas high-income White respondents tended to overestimate racial economic equality in the past, Black respondents, on average, underestimated the degree of past racial economic equality. Two follow-up experiments further revealed that making societal racial discrimination salient increased the accuracy of Whites' estimates of Black-White economic equality, whereas encouraging Whites to anchor their estimates on their own circumstances increased their tendency to overestimate current racial economic equality. Overall, these findings suggest a profound misperception of and unfounded optimism regarding societal race-based economic equality-a misperception that is likely to have any number of important policy implications.

Deciphering Martian climatic history using returned samples

NASA Technical Reports Server (NTRS)

Paige, D. A.; Krieger, D. B.; Brigham, C. A.

1988-01-01

By necessity, a Mars sample return mission must sample the upper few meters of the Martian surface. This material was subjected to a wide variety of physical processes. Presently, the most important processes are believed to be wind-driven erosion and deposition, and water ice accumulation at higher latitudes. A sample return mission represents an opportunity to better understand and quantify these important geological processes. By obtaining sample cores at key locations, it may be possible to interpret much of recent Martian climatic history.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY-PESTICIDES AND POLYCHLORINATED BIPHENYLS (PCBS) IN BLOOD ANALYTICAL RESULTS

EPA Science Inventory

The Pesticides and PCBs in Blood data set contains analytical results for measurements of up to 11 pesticides and up to 36 PCBs in 86 blood samples over 86 households. Each sample was collected as a venous sample from the primary respondent within each household. The samples co...

Attrition analysed in five waves of a longitudinal yearly survey of smokers: findings from the ITC Netherlands survey.

PubMed

Zethof, Dennis; Nagelhout, Gera E; de Rooij, Mark; Driezen, Pete; Fong, Geoffrey T; van den Putte, Bas; Hummel, Karin; de Vries, Hein; Thompson, Mary E; Willemsen, Marc C

2016-08-01

Attrition bias can affect the external validity of findings. This article analyses attrition bias and assesses the effectiveness of replenishment samples on demographic and smoking-related characteristics for the International Tobacco Control Netherlands Survey, a longitudinal survey among smokers. Attrition analyses were conducted for the first five survey waves (2008-12). We assessed, including and excluding replenishment samples, whether the demographic composition of the samples changed between the first and fifth waves. Replenishment samples were tailored to ensure the sample remained representative of the smoking population. We also constructed a multivariable survival model of attrition that included all five waves with replenishment samples. Of the original 1820 respondents recruited in 2008, 46% participated again in 2012. Demographic differences between waves due to attrition were generally small and replenishment samples tended to minimize them further. The multivariable survival analysis revealed that only two of the 10 variables analysed were significant predictors of attrition: a weak effect for gender (men dropped out more often) and weak to moderate effects for age (respondents aged 15-24 years dropped out more than aged 25-39 years, who dropped out more than those aged 40+ years). Weak to moderate attrition effects were found for men and younger age groups. This information could be used to minimize respondent attrition. Our findings suggest that sampling weights and tailored replenishment samples can effectively compensate for attrition effects. This is already being done for the International Tobacco Control Netherlands Survey, including the categories that significantly predicted attrition in this study. © The Author 2016. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Identifying Careless Responding With the Psychopathic Personality Inventory-Revised Validity Scales.

PubMed

Marcus, David K; Church, Abere Sawaqdeh; O'Connell, Debra; Lilienfeld, Scott O

2018-01-01

The Psychopathic Personality Inventory-Revised (PPI-R) includes validity scales that assess Deviant Responding (DR), Virtuous Responding, and Inconsistent Responding. We examined the utility of these scales for identifying careless responding using data from two online studies that examined correlates of psychopathy in college students (Sample 1: N = 583; Sample 2: N = 454). Compared with those below the cut scores, those above the cut on the DR scale yielded consistently lower validity coefficients when PPI-R scores were correlated with corresponding scales from the Triarchic Psychopathy Measure. The other three PPI-R validity scales yielded weaker and less consistent results. Participants who completed the studies in an inordinately brief amount of time scored significantly higher on the DR and Virtuous Responding scales than other participants. Based on the findings from the current studies, researchers collecting PPI-R data online should consider identifying and perhaps screening out respondents with elevated scores on the DR scale.

Prevalence of drug use during sex amongst MSM in Europe: Results from a multi-site bio-behavioural survey.

PubMed

Rosińska, Magdalena; Gios, Lorenzo; Nöstlinger, Christiana; Vanden Berghe, Wim; Marcus, Ulrich; Schink, Susanne; Sherriff, Nigel; Jones, Anna-Marie; Folch, Cinta; Dias, Sonia; Velicko, Inga; Mirandola, Massimo

2018-05-01

Substance use has been consistently reported to be more prevalent amongst Men who have Sex with Men (MSM) compared to the general population. Substance use, in particular polydrug use, has been found to be influenced by social and contextual factors and to increase the risk of unprotected intercourse among MSM. The objective of this analysis was to investigate the prevalence and predictors of drug use during a sexual encounter and to identify specific prevention needs. A multi-site bio-behavioural cross-sectional survey was implemented in 13 European cities, targeting MSM and using Time-Location Sampling and Respondent-Driven Sampling methods Multivariable multi-level logistic random-intercept model (random effect of study site) was estimated to identify factors associated with the use of alcohol, cannabis, party drugs, sexual performance enhancement drugs and chemsex drugs. Overall, 1261 (30.0%) participants reported drug use, and 436 of 3706 (11.8%) reported the use of two or more drugs during their last sexual encounter. By drug class, 966 (23.0%) reported using sexual performance enhancement drugs, 353 (8.4%) - party drugs, and 142 (3.4%) the use of chemsex drugs. Respondents who reported drug use were more frequently diagnosed with HIV (10.5% vs. 3.9%) before and with other STIs during the 12 months prior to the study (16.7% vs. 9.2%). The use of all the analysed substances was significantly associated with sexual encounter with more than one partner. Substance and polydrug use during sexual encounters occurred amongst sampled MSM across Europe although varying greatly between study sites. Different local social norms within MSM communities may be important contextual drivers of drug use, highlighting the need for innovative and multi-faceted prevention measures to reduce HIV/STI risk in the context of drug use. Copyright © 2018 Elsevier B.V. All rights reserved.

Delayed Matching to Sample: Probability of Responding in Accord with Equivalence as a Function of Different Delays

ERIC Educational Resources Information Center

Arntzen, Erik

2006-01-01

The present series of 4 experiments investigated the probability of responding in accord with equivalence in adult human participants as a function of increasing or decreasing delays in a many-to-one (MTO) or comparison-as-node and one-to-many (OTM) or sample-as-node conditional discrimination procedure. In Experiment 1, 12 participants started…

Effectiveness of a Time-Limited Incentive on Participation by Hard-to-Reach Respondents in a Panel Study

ERIC Educational Resources Information Center

Fomby, Paula; Sastry, Narayan; McGonagle, Katherine A.

2017-01-01

We describe an experiment to provide a time-limited incentive among a random sample of 594 hard-to-reach respondents, 200 of whom were offered the incentive to complete all survey components of a study during a three-week winter holiday period. Sample members were primary caregivers of children included in the 2014 Child Development Supplement to…

Sampling bias in an international internet survey of diversion programs in the criminal justice system.

PubMed

Hartford, Kathleen; Carey, Robert; Mendonca, James

2007-03-01

Despite advances in the storage and retrieval of information within health care systems, health researchers conducting surveys for evaluations still face technical barriers that may lead to sampling bias. The authors describe their experience in administering a Web-based, international survey to English-speaking countries. Identifying the sample was a multistage effort involving (a) searching for published e-mail addresses, (b) conducting Web searches for publicly funded agencies, and (c) performing literature searches, personal contacts, and extensive Internet searches for individuals. After pretesting, the survey was converted into an electronic format accessible by multiple Web browsers. Sampling bias arose from (a) system incompatibility, which did not allow potential respondents to open the survey, (b) varying institutional gate-keeping policies that "recognized" the unsolicited survey as spam, (c) culturally unique program terminology, which confused some respondents, and (d) incomplete sampling frames. Solutions are offered to the first three problems, and the authors note that sampling bias remains a crucial problem.

Epidemiology of HIV and hepatitis C infection among women who inject drugs in Northeast India: a respondent-driven sampling study.

PubMed

McFall, Allison M; Solomon, Sunil S; Lucas, Greg M; Celentano, David D; Srikrishnan, Aylur K; Kumar, Muniratnam S; Mehta, Shruti H

2017-08-01

Despite extensive research on HIV and hepatitis C (HCV) among people who inject drugs (PWID), there remains a gap in knowledge on the burden among women who inject drugs and their unique contexts and risk factors. This analysis compares HIV and HCV prevalence in female and male PWID and estimates injection and sexual risk correlates of prevalent HIV and HCV infection among women in Northeast India. Cross-sectional sample accrued using respondent-driven sampling. Seven cities in Northeast India, 2013. A total of 6457 adult PWID. Participants completed an interviewer-administered survey. HIV infection was diagnosed on-site and HCV antibody testing was performed on stored specimens. HIV and HCV prevalence estimates were stratified by gender. Among women, the association of risk correlates with HIV and HCV were estimated using multi-level logistic regression models. A total of 796 (15.9%) of the PWID were women, of whom 52.9% [95% confidence interval (CI) = 49.3-56.5%] were HIV-infected and 22.3% (CI = 19.9-24.7%) were HCV-infected. HIV and HCV prevalence among men was 17.4% (CI = 16.9-24.7%) and 30.4% (CI = 31.2-32.0%), respectively. Among women, correlates of HIV were widowhood [adjusted odds ratio (aOR) versus currently married = 4.03, CI = 2.13-7.60] and a higher number of life-time sexual partners (aOR ≥8 versus none = 3.08, CI = 1.07-8.86). Correlates of HCV were longer injection duration (aOR per 10 years = 1.70, CI = 1.25-2.27), injecting only heroin and a combination of drugs (aOR versus pharmaceuticals only = 5.63, CI = 1.68-18.9 and aOR = 2.58, CI = 1.60-4.16, respectively), sharing needles/syringes (aOR = 2.46, CI = 1.29-4.56) and a larger PWID network (aOR ≥ 51 versus 1-5 = 4.17, CI = 2.43-7.17). Women who inject drugs in Northeast India have a high HIV prevalence, which was more than double their hepatitis C (HCV) prevalence, an opposite pattern than is observed typically among male PWID. HIV infection is associated with sexual risk factors while injection-related behaviors appear to drive HCV infection. © 2017 Society for the Study of Addiction.

A person-centred segmentation study in elderly care: towards efficient demand-driven care.

PubMed

Eissens van der Laan, M R; van Offenbeek, M A G; Broekhuis, H; Slaets, J P J

2014-07-01

Providing patients with more person-centred care without increasing costs is a key challenge in healthcare. A relevant but often ignored hindrance to delivering person-centred care is that the current segmentation of the population and the associated organization of healthcare supply are based on diseases. A person-centred segmentation, i.e., based on persons' own experienced difficulties in fulfilling needs, is an elementary but often overlooked first step in developing efficient demand-driven care. This paper describes a person-centred segmentation study of elderly, a large and increasing target group confronted with heterogeneous and often interrelated difficulties in their functioning. In twenty-five diverse healthcare and welfare organizations as well as elderly associations in the Netherlands, data were collected on the difficulties in biopsychosocial functioning experienced by 2019 older adults. Data were collected between March 2010 and January 2011 and sampling took place based on their (temporarily) living conditions. Factor Mixture Model was conducted to categorize the respondents into segments with relatively similar experienced difficulties concerning their functioning. First, the analyses show that older adults can be empirically categorized into five meaningful segments: feeling vital; difficulties with psychosocial coping; physical and mobility complaints; difficulties experienced in multiple domains; and feeling extremely frail. The categorization seems robust as it was replicated in two population-based samples in the Netherlands. The segmentation's usefulness is discussed and illustrated through an evaluation of the alignment between a segment's unfulfilled biopsychosocial needs and current healthcare utilization. The set of person-centred segmentation variables provides healthcare providers the option to perform a more comprehensive first triage step than only a disease-based one. The outcomes of this first step could guide a focused and, therefore, more efficient second triage step. On a local or regional level, this person-centred segmentation provides input information to policymakers and care providers for the demand-driven allocation of resources. Copyright © 2014 Elsevier Ltd. All rights reserved.

Risk Behaviors, Prevalence of HIV and Hepatitis C Virus Infection and Population Size of Current Injection Drug Users in a China-Myanmar Border City: Results from a Respondent-Driven Sampling Survey in 2012

PubMed Central

Li, Lei; Assanangkornchai, Sawitri; Duo, Lin; McNeil, Edward; Li, Jianhua

2014-01-01

Background Injection drug use has been the major cause of HIV/AIDS in China in the past two decades. We measured the prevalences of HIV and hepatitis C virus (HCV) prevalence and their associated risk factors among current injection drug users (IDUs) in Ruili city, a border region connecting China with Myanmar that has been undergoing serious drug use and HIV spread problems. An estimate of the number of current IDUs is also presented. Methods In 2012, Chinese IDUs who had injected within the past six months and aged ≥18 years were recruited using a respondent-driven sampling (RDS) technique. Participants underwent interviews and serological testing for HIV, HBV, HCV and syphilis. Logistic regression indentified factors associated with HIV and HCV infections. Multiplier method was used to obtain an estimate of the size of the current IDU population via combining available service data and findings from our survey. Results Among 370 IDUs recruited, the prevalence of HIV and HCV was 18.3% and 41.5%, respectively. 27.1% of participants had shared a needle/syringe in their lifetime. Consistent condom use rates were low among both regular (6.8%) and non-regular (30.4%) partners. Factors independently associated with being HIV positive included HCV infection, having a longer history of injection drug use and experience of needle/syringe sharing. Participants with HCV infection were more likely to be HIV positive, have injected more types of drugs, have shared other injection equipments and have unprotected sex with regular sex partners. The estimated number of current IDUs in Ruili city was 2,714 (95% CI: 1,617–5,846). Conclusions IDUs may continue to be a critical subpopulation for transmission of HIV and other infections in this region because of the increasing population and persistent high risk of injection and sexual behaviours. Developing innovative strategies that can improve accessibility of current harm reduction services and incorporate more comprehensive contents is urgently needed. PMID:25203256

Access to harm reduction programs among persons who inject drugs: findings from a respondent-driven sampling survey in Tehran, Iran.

PubMed

Rahnama, Ruyan; Mohraz, Minoo; Mirzazadeh, Ali; Rutherford, George; McFarland, Willi; Akbari, Gholamreza; Malekinejad, Mohsen

2014-07-01

Over the past two decades, drug injection-related risk behaviors have been the major drivers of the HIV epidemic in Iran. This study assesses the access of people who injected drugs (PWID) to harm reduction services (needle-exchange programs [NEP] and methadone maintenance treatment [MMT]) in Tehran, Iran in 2007, almost five years after the large-scale implementation of these programs. 572 consenting PWID (>18 years old, ever injected in the past month, lived in Tehran or its suburbs) were recruited (24 seeds) into a sero-behavioral survey using respondent-driven sampling method. Participants completed a face-to-face interview about HIV-related risk behaviors and access to harm reduction services. We calculated adjusted population estimates using RDSAT. Overall, 99.2% of the participants were male, 41.6% aged between 30 and 39 years old, 55.4% lived alone in the past year, 83.2% were ever incarcerated, and 88.8% lived in the southern areas of Tehran. In terms of "awareness" and "use" of services among PWID, 62.8% and 54.8% reported for NEP (respectively) and 19.7% and 9.1% for drug treatment services (respectively). PWID who lived in Northwest and South-central Tehran were more likely to be aware (85.0% and 82.8%, respectively) of one or more services than PWID who lived elsewhere. Similarly, PWID who lived with friends were more likely to be aware of (88.6%) and use (85.9%) services (vs. other living partners). Overall, 11% of the participants were aware of but had not used any harm reduction services. Despite a relatively high level of access to NEP among PWID in Tehran, a sizable fraction of the population remains without access to other services five years after their implementation. The use of harm reduction may be affected by certain PWID characteristics (e.g., living partners and geographical location). Ongoing surveillance activities are necessary to track change in access over time. Copyright © 2014 Elsevier B.V. All rights reserved.

Hybrid STTR intervention for heterosexuals using anonymous HIV testing and confidential linkage to care: a single arm exploratory trial using respondent-driven sampling.

PubMed

Gwadz, Marya; Cleland, Charles M; Leonard, Noelle R; Kutnick, Alexandra; Ritchie, Amanda S; Banfield, Angela; Hagan, Holly; Perlman, David C; McCright-Gill, Talaya; Sherpa, Dawa; Martinez, Belkis Y

2015-11-16

An estimated 14 % of the 1.2 million individuals living with HIV in the U.S. are unaware of their status. Yet this modest proportion of individuals with undiagnosed HIV is linked to 44-66 % of all new infections. Thus innovative intervention approaches are needed to seek out and test those with undiagnosed HIV, and link them to HIV treatment with high retention, an approach referred to as "Seek, Test, Treat, and Retain" (STTR). The present protocol describes a creative "hybrid" STTR approach that uses anonymous HIV testing followed by confidential care linkage, focused on heterosexuals at high risk (HHR) for HIV, who do not test as frequently as, and are diagnosed later, than other risk groups. This is a single-arm exploratory intervention efficacy trial. The study has two phases: one to seek out and test HHR, and another to link those found infected to HIV treatment in a timely fashion, with high retention. We will recruit African American/Black and Latino adult HHR who reside in urban locations with high poverty and HIV prevalence. Participants will be recruited with respondent-driven sampling, a peer recruitment method. The "Seek and Test" phase is comprised of a brief, convenient, single-session, anonymous HIV counseling and testing session. The "Treat and Retain" component will engage those newly diagnosed with HIV into a confidential research phase and use a set of procedures called care navigation to link them to HIV primary care. Participants will be followed for 6 months with objective assessment of outcomes (using medical records and biomarkers). Undiagnosed HIV infection is a major public health problem. While anonymous HIV testing is an important part of the HIV testing portfolio, it does not typically include linkage to care. The present study has potential to produce an innovative, brief, cost-effective, and replicable STTR intervention, and thereby reduce racial/ethnic disparities in HIV/AIDS. ClinicalTrials.gov, NCT02421159 , Registered April 15, 2015.

Evaluating Respondent-Driven Sampling as an Implementation Tool For Universal Coverage of Antiretroviral Studies among Men who have Sex with Men Living with HIV

PubMed Central

Baral, Stefan D.; Ketende, Sosthenes; Schwartz, Sheree; Orazulike, Ifeanyi; Ugoh, Kelechi; Peel, Sheila; Ake, Julie; Blattner, William; Charurat, Manhattan

2015-01-01

Introduction The TRUST model based on experimental and observational data posits that integration of HIV prevention and universal coverage of antiretroviral treatment (UCT) at a trusted community venue provides a framework for achieving effective reduction in HIV-related morbidity and mortality among men who have sex with men (MSM) living with HIV as well as reducing HIV incidence. The analyses presented here evaluate the utility of respondent-driven sampling (RDS) as an implementation tool for engaging MSM in the TRUST intervention. Methods The TRUST integrated prevention and treatment model was established at a trusted community center serving MSM in Abuja Nigeria. Five seeds have resulted in 3–26 waves of accrual between March, 2013 and August, 2014 with results presented here characterizing HIV burden and engagement in HIV care for 722 men across study recruitment waves. For analytic purposes, the waves were collapsed into five groups; four equally spaced (0–4, 5–9, 10–14, 15–19) and one ranging from the 20 to the 26th wave with significance assessed using Pearson’s chi-squared test. Results In earlier waves, MSM were more likely to have reported testing for HIV (82.9% in waves 0–4, 47.7% in waves 20–26, p<0.01). In addition, biologically-confirmed HIV prevalence decreased from an average of 59.1 to 42.9% (p<0.05) in later waves. In earlier waves, about 80% of participants correctly reported their HIV status as compared to less than 25% in the later waves (p<0.01). Lastly, participants reporting being on ART decreased from 50% to 22.2 % in later waves (p<0.01). Conclusions Implementation science studies focused on demonstrating impact of universal HIV-treatment programs among people living with HIV necessitate different accrual methods than those focused on preventing HIV acquisition. Here, RDS was shown to be an efficient method for reaching marginalized populations of MSM living with HIV in Nigeria and engaging them in universal HIV treatment services. PMID:25723974

The use of respondent-driven sampling to assess malaria knowledge, treatment-seeking behaviours and preventive practices among mobile and migrant populations in a setting of artemisinin resistance in Western Cambodia.

PubMed

Ly, Po; Thwing, Julie; McGinn, Colleen; Quintero, Cesia E; Top-Samphor, Narann; Habib, Najibullah; Richards, Jack S; Canavati, Sara E; Vinjamuri, Seshu Babu; Nguon, Chea

2017-09-19

Multi-drug-resistant Plasmodium falciparum threatens malaria elimination efforts in Cambodia and the Greater Mekong Subregion (GMS). Malaria burden in the GMS is higher among certain high-risk demographic groups in Cambodia, especially among migrant and mobile populations (MMPs). This respondent driven sampling (RDS) study was conducted in order to determine malaria knowledge, treatment-seeking behaviours and preventive practices among two MMP groups in Western Cambodia. An RDS survey of MMPs was implemented in four purposively-selected communes along the Thai-Cambodia border; two in Veal Veang District and two in Pailin Province, chosen due to their sizeable MMP groups, their convenience of access, and their proximity to Thailand, which allowed for comparison with RDS studies in Thailand. There were 764 participants in Pailin Province and 737 in Veal Veang District. Health messages received in Veal Veang were most likely to come from billboards (76.5%) and family and friends (57.7%), while in Pailin they were most likely to come from sources like radio (57.1%) and television (31.3%). Knowledge of malaria transmission by mosquito and prevention by bed net was above 94% in both locations, but some misinformation regarding means of transmission and prevention methods existed, predominantly in Veal Veang. Ownership of treated bed nets was lower in Pailin than in Veal Veang (25.3% vs 53.2%), while reported use the night before the survey was higher in Pailin than in Veal Veang (57.1% vs 31.6%). Use of private sector health and pharmaceutical services was common, but 81.1% of patients treated for malaria in Pailin and 86.6% in Veal Veang had received a diagnostic test. Only 29.6% of patients treated in Pailin and 19.6% of those treated in Veal Veng reported receiving the indicated first-line treatment. Barriers in access to malaria prevention and case management were common among MMPs, with marked variation by site. Resolving both nation-wide and MMP-specific challenges will require targeted interventions that take into account this heterogeneity.

Respondent-driven sampling to assess mental health outcomes, stigma and acceptance among women raising children born from sexual violence-related pregnancies in eastern Democratic Republic of Congo.

PubMed

Scott, Jennifer; Rouhani, Shada; Greiner, Ashley; Albutt, Katherine; Kuwert, Philipp; Hacker, Michele R; VanRooyen, Michael; Bartels, Susan

2015-04-08

Assess mental health outcomes among women raising children from sexual violence-related pregnancies (SVRPs) in eastern Democratic Republic of Congo and stigma toward and acceptance of women and their children. Participants were recruited using respondent-driven sampling. Bukavu, Democratic Republic of Congo in 2012. 757 adult women raising children from SVRPs were interviewed. A woman aged 18 and older was eligible for the study if she self-identified as a sexual violence survivor since the start of the conflict (∼1996), conceived an SVRP, delivered a liveborn child and was currently raising the child. A woman was ineligible for the study if the SVRP ended with a spontaneous abortion or fetal demise or the child was not currently living or in the care of the biological mother. Trained female Congolese interviewers verbally administered a quantitative survey after obtaining verbal informed consent. Symptom criteria for major depressive disorder, post-traumatic stress disorder, anxiety and suicidality were assessed, as well as stigma toward the woman and her child. Acceptance of the woman and child from the spouse, family and community were analysed. 48.6% met symptom criteria for major depressive disorder, 57.9% for post-traumatic stress disorder, 43.3% for anxiety and 34.2% reported suicidality. Women who reported stigma from the community (38.4%) or who reported stigma toward the child from the spouse (42.9%), family (31.8%) or community (38.1%) were significantly more likely to meet symptom criteria for most mental health disorders. Although not statistically significant, participants who reported acceptance and acceptance of their children from the spouse, family and community were less likely to meet symptom criteria. Women raising children from SVRPs experience symptoms of mental health disorders. Programming addressing stigma and acceptance following sexual violence may improve mental health outcomes in this population. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Consumers' acceptance of innovations in traditional cheese. A comparative study in France and Norway.

PubMed

Almli, Valérie Lengard; Naes, Tormod; Enderli, Géraldine; Sulmont-Rossé, Claire; Issanchou, Sylvie; Hersleth, Margrethe

2011-08-01

This study explores consumers' acceptance of innovations in traditional cheese in France (n=120) and Norway (n=119). The respondents were presented with 16 photographs of a traditional cheese from their respective countries, varying according to six factors: pasteurisation, organic production, omega-3, packaging, price and appropriateness. For each of the scenarios the consumers indicated their willingness to buy the cheese on a nine-point scale. Results show that consumers' willingness to buy traditional cheese is highly driven by price, appropriateness and pasteurisation in both countries. However, on average consumers in the French sample prefer buying raw milk cheese, while consumers in the Norwegian sample prefer buying pasteurised cheese. These general trends are led by a pro-raw milk segment in France and a pro-pasteurised milk segment in Norway. Several interaction effects involving appropriateness are detected, indicating the importance of the consumption context on the acceptance of innovations in traditional cheese. On a general level, the results indicate that well-accepted innovations in traditional cheese are those that reinforce the traditional and authentic character of the product. Copyright © 2011 Elsevier Ltd. All rights reserved.

Ethical considerations in investigating youth alcohol norms and behaviours: a case for mature minor consent.

PubMed

Hildebrand, J; Maycock, B; Comfort, J; Burns, S; Adams, E; Howat, P

2015-12-01

Mature minor consent only became available in Australia in 2007. There is neither an explicitly defined protocol, nor a clear definition evident in the literature relating to use of the mature minor concept in health research. Due to difficulties in defining fixed age ranges to varying levels of maturity and vulnerability, there is a lack of clarity surrounding when it might be reasonable and ethical to apply for or grant a waiver for parental consent. This paper describes the challenges faced and solutions created when gaining approval for use of mature minor consent in a respondent-driven sampling (RDS) study to explore the social norms and alcohol consumption among 14-17-year-old adolescents (n = 1012) in the community. The University's Human Research Ethics Committee granted mature minor consent for this study, and the techniques applied enabled recruitment of adolescents from community-based settings through use of RDS to achieve the required sample. This paper has relevance for research that requires a waiver for parental consent; it presents a case study for assessing mature minors and makes recommendations on how ethical guidelines can be improved to assist human research ethics application processes.

Comparing Selected Measures of Health Outcomes and Health-Seeking Behaviors in Chinese, Cambodian, and Vietnamese Communities of Chicago: Results from Local Health Surveys

PubMed Central

Guo, Lucy; Magee, Matthew; Cheung, William; Simon, Melissa; LaBreche, Amanda; Liu, Hong

2010-01-01

We describe how local community organizations partnered to conduct a survey in the Chinese, Cambodian, and Vietnamese populations of Chicago to compare health outcomes and assess progress toward Healthy People 2010 goals. Interviews were conducted with 380 randomly selected Chinese adults through door-to-door sampling, and with 250 Cambodian adults and 150 Vietnamese adults through respondent-driven sampling. Data on 14 key health outcomes are described for this analysis. The three surveyed communities were generally poorer, less educated, more often foreign-born, and had less English proficiency than Asians nationally. There were few significant variations among the three populations, but there were notable differences in the burden of tuberculosis, obesity, diabetes, and arthritis. Insurance coverage and cancer-screening utilization were also significantly lower than for US Asians. Health information about Chinese, Cambodian, and Vietnamese populations in Chicago are available for the first time and serve as baseline data for community interventions. Findings highlight important health concerns for these populations and have implications for funders and policy makers in allocating resources, setting health priorities, and addressing health disparities. PMID:20625846

Factors associated with self-reported discrimination against men who have sex with men in Brazil.

PubMed

Magno, Laio; Dourado, Inês; da Silva, Luís Augusto V; Brignol, Sandra; Brito, Ana Maria de; Guimarães, Mark Drew Crosland; Benzaken, Adele; Pinho, Adriana de A; Kendall, Carl; Kerr, Ligia Regina Franco Sansigolo

2017-01-01

To estimate self-reported discrimination due to sexual orientation among men who have sex with men (MSM) in Brazil and to analyze associated factors. A cross-sectional study of 3,859 MSM recruited in 2008-2009 with respondent driven sampling. Data collection conducted in health centers in 10 Brazilian cities. A face-to-face questionnaire was used and rapid HIV and syphilis tests conducted. Aggregated data were weighted and adjusted odds ratio estimated to measure the association between selected factors and self-reported discrimination due to sexual orientation. The sample was predominantly young, eight plus years of schooling, pardo (brown), single, low-income, and identified themselves as gay or homosexual. The prevalence of self-reported discrimination due to sexual orientation was 27.7% (95%CI 26.2-29.1). Discrimination was independently associated with: age < 30 years, more years of schooling, community involvement and support, history of sexual and physical violence, suicidal thoughts, and unprotected receptive anal intercourse. The prevalence of self-reported discrimination among MSM in Brazil is high. These results challenge the assumptions that MSM-specific prevention and support programs are not required or that health professionals do not need special training to address MSM needs.

Use of Pre-exposure Prophylaxis (PrEP) in Young Men Who Have Sex with Men is Associated with Race, Sexual Risk Behavior and Peer Network Size.

PubMed

Kuhns, Lisa M; Hotton, Anna L; Schneider, John; Garofalo, Robert; Fujimoto, Kayo

2017-05-01

Pre-exposure prophylaxis (PrEP) is efficacious to prevent HIV infection, however, uptake among young men who have sex with men (YMSM) is relatively low. The purpose of this study was to describe PrEP use and related factors in a representative sample of YMSM in two cities, Chicago and Houston. YMSM, ages 16-29, were recruited via respondent-driven sampling (RDS) from 2014 to 2016. Correlates of PrEP uptake were assessed in weighted multivariable logistic regression models. A total of 12.2% of participants (of 394) reported ever taking PrEP; Black YMSM had the lowest rates of uptake (4.7%) and Whites the highest (29.5%). In a multivariable regression model, having an HIV positive sex partner, reporting recent group sex, peer network size, and city (Chicago) were significantly and positively associated with use of PrEP, while Black race was negatively associated with it. Given evidence of racial/ethnic disparities in PrEP uptake in this study, further research is needed to identify potential mechanisms of action and points of intervention.

Police-related experiences and HIV risk among female sex workers in Andhra Pradesh, India.

PubMed

Erausquin, Jennifer Toller; Reed, Elizabeth; Blankenship, Kim M

2011-12-01

Research suggests experiences with police are related to human immunodeficiency virus (HIV) sexual risk among women working as sex workers. However, little is known about the links between specific police-related behaviors and HIV vulnerability. We examine whether 5 police-related experiences are associated with measures of HIV risk and violence among a sample of female sex workers (FSWs) in Andhra Pradesh, India, and consider the implications for HIV prevention. FSWs at least 18 years of age (n = 835) were recruited through respondent-driven sampling for a cross-sectional survey conducted as part of Avahan, the India AIDS Initiative. Using logistic regression models adjusted for age, age at start of sex work, and sex work venue, we assessed police-related experiences reported by FSWs in relation to HIV risk behaviors and violence. Results showed having sex with police to avoid trouble, giving gifts to police to avoid trouble, having police take condoms away, experiencing a workplace raid, and being arrested were associated with sexually transmitted infection symptoms, inconsistent condom use, acceptance of more money for sex without a condom, and experience of client violence. These findings suggest a need for interventions targeting police-FSW interactions to reduce HIV vulnerability among FSWs.

An Empirical Analysis of the Impact of Recruitment Patterns on RDS Estimates among a Socially Ordered Population of Female Sex Workers in China

PubMed Central

Yamanis, Thespina J.; Merli, M. Giovanna; Neely, William Whipple; Tian, Felicia Feng; Moody, James; Tu, Xiaowen; Gao, Ersheng

2013-01-01

Respondent-driven sampling (RDS) is a method for recruiting “hidden” populations through a network-based, chain and peer referral process. RDS recruits hidden populations more effectively than other sampling methods and promises to generate unbiased estimates of their characteristics. RDS’s faithful representation of hidden populations relies on the validity of core assumptions regarding the unobserved referral process. With empirical recruitment data from an RDS study of female sex workers (FSWs) in Shanghai, we assess the RDS assumption that participants recruit nonpreferentially from among their network alters. We also present a bootstrap method for constructing the confidence intervals around RDS estimates. This approach uniquely incorporates real-world features of the population under study (e.g., the sample’s observed branching structure). We then extend this approach to approximate the distribution of RDS estimates under various peer recruitment scenarios consistent with the data as a means to quantify the impact of recruitment bias and of rejection bias on the RDS estimates. We find that the hierarchical social organization of FSWs leads to recruitment biases by constraining RDS recruitment across social classes and introducing bias in the RDS estimates. PMID:24288418

HIV Research with Men who Have Sex with Men (MSM): Advantages and Challenges of Different Methods for Most Appropriately Targeting a Key Population

PubMed Central

Gama, Ana; Martins, Maria O.; Dias, Sónia

2017-01-01

The difficulty in accessing hard-to-reach populations as men who have sex with men presents a dilemma for HIV surveillance as their omission from surveillance systems leaves significant gaps in our understanding of HIV/AIDS epidemics. Several methods for recruiting difficult-to-access populations and collecting data on trends of HIV prevalence and behavioural factors for surveillance and research purposes have emerged. This paper aims to critically review different sampling approaches, from chain-referral and venue-based to respondent-driven, time-location and internet sampling methods, focusing on its main advantages and challenges for conducting HIV research among key populations, such as men who have sex with men. The benefits of using these approaches to recruit participants must be weighed against privacy concerns inherent in any social situation or health condition. Nevertheless, the methods discussed in this paper represent some of the best efforts to effectively reach most-at-risk subgroups of men who have sex with men, contributing to obtain unbiased trends of HIV prevalence and HIV-related risk behaviours among this population group. PMID:29546214

Research and Engagement Strategies for Young Adult Immigrants Without Documentation: Lessons Learned Through Community Partnership.

PubMed

Raymond-Flesch, Marissa; Siemons, Rachel; Brindis, Claire D

2016-01-01

Limited research has focused on undocumented immigrants' health and access to care. This paper describes participant engagement strategies used to investigate the health needs of immigrants eligible for Deferred Action for Childhood Arrivals (DACA). Community-based strategies engaged advocates and undocumented Californians in study design and recruitment. Outreach in diverse settings, social media, and participant-driven sampling recruited 61 DACA-eligible focus group participants. Social media, community-based organizations (CBOs), family members, advocacy groups, and participant-driven sampling were the most successful recruitment strategies. Participants felt engaging in research was instrumental for sharing their concerns with health care providers and policymakers, noteworthy in light of their previously identified fears and mistrust of government officials. Using multiple culturally responsive strategies including participant-driven sampling, engagement with CBOs, and use of social media, those eligible for DACA eagerly engage as research participants. Educating researchers and institutional review boards (IRBs) about legal and safety concerns can improve research engagement.

Evolution of Starburst Galaxies in the Illustris Simulation

NASA Astrophysics Data System (ADS)

Wilkinson, C. L.; Pimbblet, K. A.; Stott, J. P.; Few, C. G.; Gibson, B. K.

2018-06-01

There is a consensus in the literature that starburst galaxies are triggered by interaction events. However, it remains an open question as to what extent both merging and non-merging interactions have in triggering starbursts? In this study, we make use of the Illustris simulation to test how different triggering mechanisms can effect starburst events. We examine star formation rate, colour and environment of starburst galaxies to determine if this could be why we witness a bimodality in post-starburst populations within observational studies. Further, we briefly test the extent of quenching due to AGN feedback. From Illustris, we select 196 starburst galaxies at z = 0.15 and split them into post-merger and pre-merger/harassment driven starburst samples. We find that 55% of this sample not undergone a merger in the past 2 Gyr. Both of our samples are located in low-density environments within the filament regions of the cosmic web, however we find that pre-merger/harassment driven starburst are in higher density environments than post-merger driven starbursts. We also find that pre-merger/harassment starbursts are redder than post-merger starbursts, this could be driven by environmental effects. Both however, produce nuclear starbursts of comparable strengths.

Characterizing Contamination and Assessing Exposure, Risk and Resilience

EPA Pesticide Factsheets

EPA supports its responders' ability to characterize site contamination by developing sampling protocols, sample preparation methods, and analytical methods for chemicals, biotoxins, microbial pathogens, and radiological agents.

Assessing generative braille responding following training in a matching-to-sample format.

PubMed

Putnam, Brittany C; Tiger, Jeffrey H

2016-12-01

We evaluated the effects of teaching sighted college students to select printed text letters given a braille sample stimulus in a matching-to-sample (MTS) format on the emergence of untrained (a) construction of print characters given braille samples, (b) construction of braille characters given print samples, (c) transcription of print characters given braille sample sentences, and (d) vocal reading given braille sample passages. The results demonstrated the generative development of these repertoires given MTS instruction. © 2016 Society for the Experimental Analysis of Behavior.

A computational framework for estimating statistical power and planning hypothesis-driven experiments involving one-dimensional biomechanical continua.

PubMed

Pataky, Todd C; Robinson, Mark A; Vanrenterghem, Jos

2018-01-03

Statistical power assessment is an important component of hypothesis-driven research but until relatively recently (mid-1990s) no methods were available for assessing power in experiments involving continuum data and in particular those involving one-dimensional (1D) time series. The purpose of this study was to describe how continuum-level power analyses can be used to plan hypothesis-driven biomechanics experiments involving 1D data. In particular, we demonstrate how theory- and pilot-driven 1D effect modeling can be used for sample-size calculations for both single- and multi-subject experiments. For theory-driven power analysis we use the minimum jerk hypothesis and single-subject experiments involving straight-line, planar reaching. For pilot-driven power analysis we use a previously published knee kinematics dataset. Results show that powers on the order of 0.8 can be achieved with relatively small sample sizes, five and ten for within-subject minimum jerk analysis and between-subject knee kinematics, respectively. However, the appropriate sample size depends on a priori justifications of biomechanical meaning and effect size. The main advantage of the proposed technique is that it encourages a priori justification regarding the clinical and/or scientific meaning of particular 1D effects, thereby robustly structuring subsequent experimental inquiry. In short, it shifts focus from a search for significance to a search for non-rejectable hypotheses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Risk Factors for Domestic Child Sex Trafficking in the United States.

PubMed

Fedina, Lisa; Williamson, Celia; Perdue, Tasha

2016-07-01

Despite increased effort to respond to human trafficking at national and state levels, very little empirical research has been conducted on domestic child sex trafficking. This study retrospectively examines associations between multiple risk factors and domestic child sex trafficking (i.e., entry into the commercial sex industry under the age of 18) in a sample of individuals aged 16 and older currently involved in the commercial sex industry ( N = 273). Two primary research questions are addressed: (1) What set of risk factors, prior to entering the commercial sex industry, are associated with domestic child sex trafficking and (2) what group differences, if any, exist in risk factors between current or former domestic child sex-trafficking victims and non-trafficked adults engaged in the commercial sex industry? A cross-sectional survey was administered using Respondent-Driven Sampling (RDS) in five cities in one Midwestern state. Overall, 115 participants (48.3%) were identified as current or former domestic child sex-trafficking victims. Bivariate results suggest that childhood emotional and sexual abuse, rape, ever running away from home, having family members in sex work, and having friends who purchased sex were significantly associated with domestic child sex trafficking. Multivariate results indicate that domestic child sex trafficking victims were significantly more likely to have ever run away and to be a racial/ethnic minority than non-trafficked adults engaged in the commercial sex industry. Findings can inform state-level policies on human trafficking and assist child protection and juvenile justice agencies in developing prevention and intervention responses to commercial sexual exploitation.

Adding Postal Follow-Up to a Web-Based Survey of Primary Care and Gastroenterology Clinic Physician Chiefs Improved Response Rates but not Response Quality or Representativeness.

PubMed

Partin, Melissa R; Powell, Adam A; Burgess, Diana J; Haggstrom, David A; Gravely, Amy A; Halek, Krysten; Bangerter, Ann; Shaukat, Aasma; Nelson, David B

2015-09-01

This study assessed whether postal follow-up to a web-based physician survey improves response rates, response quality, and representativeness. We recruited primary care and gastroenterology chiefs at 125 Veterans Affairs medical facilities to complete a 10-min web-based survey on colorectal cancer screening and diagnostic practices in 2010. We compared response rates, response errors, and representativeness in the primary care and gastroenterology samples before and after adding postal follow-up. Adding postal follow-up increased response rates by 20-25 percentage points; markedly greater increases than predicted from a third e-mail reminder. In the gastroenterology sample, the mean number of response errors made by web responders (0.25) was significantly smaller than the mean number made by postal responders (2.18), and web responders provided significantly longer responses to open-ended questions. There were no significant differences in these outcomes in the primary care sample. Adequate representativeness was achieved before postal follow-up in both samples, as indicated by the lack of significant differences between web responders and the recruitment population on facility characteristics. We conclude adding postal follow-up to this web-based physician leader survey improved response rates but not response quality or representativeness. © The Author(s) 2013.

NHEXAS PHASE I ARIZONA STUDY--METALS IN DERMAL WIPES ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Dermal Wipes data set contains analytical results for measurements of up to 11 metals in 179 dermal wipe samples over 179 households. Each sample was collected from the primary respondent within each household during Stage III of the NHEXAS study. The sampling per...

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--PESTICIDE METABOLITES IN URINE ANALYTICAL RESULTS

EPA Science Inventory

The Pesticide Metabolites in Urine data set contains the analytical results for measurements of up to 8 pesticide metabolites in 86 samples over 86 households. Each sample was collected form the primary respondent within each household. The sample consists of the first morning ...

NHEXAS PHASE I ARIZONA STUDY--METALS IN URINE ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Urine data set contains analytical results for measurements of up to 6 metals in 176 urine samples over 176 households. Each sample was collected from the primary respondent within each household during Stage III of the NHEXAS study. The sample consists of the fir...

NHEXAS PHASE I MARYLAND STUDY--LIPIDS IN BLOOD ANALYTICAL RESULTS

EPA Science Inventory

The Lipids in Blood data set presents concentrations of cholesterol and total triglycerides in blood serum. The data set presents measurements for up to 2 lipids in 358 blood samples over 79 households. Each sample was collected via a venous sample from the primary respondent w...

Predictive Service Life Tests for Roofing Membranes: Phase II Investigation of Accelerated Aging Tests for Tracking Degradation of Roofing Membrane Materials

DTIC Science & Technology

2002-09-01

bitumens, EPDM , and PVC. Most heat-driven aging tests for building materials use a temperature of 70 °C. Ultraviolet radiation exposure in the...of 0.85 mm/sec. These samples generated three types of load-strain curves. A relatively straight line was generated by each EPDM rubber sample...Mathey 1974) at -18 °C. Except for the EPDM rubber membranes and Sample H, all samples tested comply with this suggested requirement. Sample H is an

Method and apparatus for reducing sample dispersion in turns and junctions of microchannel systems

DOEpatents

Griffiths, Stewart K.; Nilson, Robert H.

2001-01-01

The performance of microchannel devices is improved by providing turns, wyes, tees, and other junctions that produce little dispersions of a sample as it traverses the turn or junction. The reduced dispersion results from contraction and expansion regions that reduce the cross-sectional area over some portion of the turn or junction. By carefully designing the geometries of these regions, sample dispersion in turns and junctions is reduced to levels comparable to the effects of ordinary diffusion. A numerical algorithm was employed to evolve low-dispersion geometries by computing the electric or pressure field within candidate configurations, sample transport through the turn or junction, and the overall effective dispersion. These devices should greatly increase flexibility in the design of microchannel devices by permitting the use of turns and junctions that do not induce large sample dispersion. In particular, the ability to fold electrophoretic and electrochrornatographic separation columns will allow dramatic improvements in the miniaturization of these devices. The low-lispersion devices are particularly suited to electrochromatographic and electrophoretic separations, as well as pressure-driven chromatographic separation. They are further applicable to microfluidic systems employing either electroosrnotic or pressure-driven flows for sample transport, reaction, mixing, dilution or synthesis.

Modeling and enhanced sampling of molecular systems with smooth and nonlinear data-driven collective variables

NASA Astrophysics Data System (ADS)

Hashemian, Behrooz; Millán, Daniel; Arroyo, Marino

2013-12-01

Collective variables (CVs) are low-dimensional representations of the state of a complex system, which help us rationalize molecular conformations and sample free energy landscapes with molecular dynamics simulations. Given their importance, there is need for systematic methods that effectively identify CVs for complex systems. In recent years, nonlinear manifold learning has shown its ability to automatically characterize molecular collective behavior. Unfortunately, these methods fail to provide a differentiable function mapping high-dimensional configurations to their low-dimensional representation, as required in enhanced sampling methods. We introduce a methodology that, starting from an ensemble representative of molecular flexibility, builds smooth and nonlinear data-driven collective variables (SandCV) from the output of nonlinear manifold learning algorithms. We demonstrate the method with a standard benchmark molecule, alanine dipeptide, and show how it can be non-intrusively combined with off-the-shelf enhanced sampling methods, here the adaptive biasing force method. We illustrate how enhanced sampling simulations with SandCV can explore regions that were poorly sampled in the original molecular ensemble. We further explore the transferability of SandCV from a simpler system, alanine dipeptide in vacuum, to a more complex system, alanine dipeptide in explicit water.

Modeling and enhanced sampling of molecular systems with smooth and nonlinear data-driven collective variables.

PubMed

Hashemian, Behrooz; Millán, Daniel; Arroyo, Marino

2013-12-07

Collective variables (CVs) are low-dimensional representations of the state of a complex system, which help us rationalize molecular conformations and sample free energy landscapes with molecular dynamics simulations. Given their importance, there is need for systematic methods that effectively identify CVs for complex systems. In recent years, nonlinear manifold learning has shown its ability to automatically characterize molecular collective behavior. Unfortunately, these methods fail to provide a differentiable function mapping high-dimensional configurations to their low-dimensional representation, as required in enhanced sampling methods. We introduce a methodology that, starting from an ensemble representative of molecular flexibility, builds smooth and nonlinear data-driven collective variables (SandCV) from the output of nonlinear manifold learning algorithms. We demonstrate the method with a standard benchmark molecule, alanine dipeptide, and show how it can be non-intrusively combined with off-the-shelf enhanced sampling methods, here the adaptive biasing force method. We illustrate how enhanced sampling simulations with SandCV can explore regions that were poorly sampled in the original molecular ensemble. We further explore the transferability of SandCV from a simpler system, alanine dipeptide in vacuum, to a more complex system, alanine dipeptide in explicit water.

Conditioned Microplitis croceipes Cresson (Hymenoptera: Braconidae) detect and respond to 2,4-DNT: development of a biological sensor.

PubMed

Tomberlin, Jeffery K; Tertuliano, Moukaram; Rains, Glen; Lewis, W Joe

2005-09-01

We examined the ability of M. croceipes to learn, detect, and respond to 2,4-DNT, which is a volatile discriminator of trinitrotoluene (TNT). The percentage of conditioned wasps to detect and respond to the various concentrations of 2,4-DNT for > or = 15 sec was measured. Significantly more of the conditioned wasps responded to the concentration of 2,4-DNT used for conditioning than other concentrations examined. Accordingly, percent conditioned wasps to respond > or = 15 sec could be used as a suitable measure to screen air samples and distinguish between samples with or without the target odorant. The data recorded in this study indicate the measured behavior could be used to estimate the concentration of target odorants. Data in this study indicate M. croceipes can detect and respond to this compound, which provide further support for its development as a biological sensor.

Respondent-driven sampling for identification of HIV- and HCV-infected people who inject drugs and men who have sex with men in India: A cross-sectional, community-based analysis.

PubMed

Solomon, Sunil S; McFall, Allison M; Lucas, Gregory M; Srikrishnan, Aylur K; Kumar, Muniratnam S; Anand, Santhanam; Quinn, Thomas C; Celentano, David D; Mehta, Shruti H

2017-11-01

A major barrier to achieving ambitious targets for global control of HIV and hepatitis C virus (HCV) is low levels of awareness of infection among key populations such as men who have sex with men (MSM) and people who inject drugs (PWID). We explored the potential of a strategy routinely used for surveillance in these groups, respondent-driven sampling (RDS), to be used as an intervention to identify HIV- and HCV-infected PWID and MSM who are unaware of their status and those who are viremic across 26 Indian cities at various epidemic stages. Data were collected as part of the baseline assessment of an ongoing cluster-randomized trial. RDS was used to accrue participants at 27 sites (15 PWID sites and 12 MSM sites) selected to reflect varying stages of the HIV epidemic among MSM and PWID in India. A total of 56 seeds recruited a sample of 26,447 persons (approximately 1,000 participants per site) between October 1, 2012, and December 19, 2013. Across MSM sites (n = 11,997), the median age was 25 years and the median number of lifetime male partners was 8. Across PWID sites (n = 14,450), 92.4% were male, the median age was 30 years, and 87.5% reported injection in the prior 6 months. RDS identified 4,051 HIV-infected persons, of whom 2,325 (57.4%) were unaware of their HIV infection and 2,816 (69.5%) were HIV viremic. It also identified 5,777 HCV-infected persons, of whom 5,337 (92.4%) were unaware that they were infected with HCV and 4,728 (81.8%) were viremic. In the overall sample (both MSM and PWID), the prevalence of HIV-infected persons who were unaware of their status increased with sampling depth, from 7.9% in participants recruited in waves 1 through 5 to 12.8% among those recruited in waves 26 and above (p-value for trend < 0.001). The overall detection rate of people unaware of their HIV infection was 0.5 persons per day, and the detection rate of HIV-infected persons with viremia (regardless of their awareness status) was 0.7 per day. The detection rate of HIV viremic individuals was positively associated with underlying HIV prevalence and the prevalence of HIV viremia (linear regression coefficient per 1-percentage-point increase in prevalence: 0.05 and 0.07, respectively). The median detection rate of PWID who were unaware of their HCV infection was 2.5 per day. The cost of identifying 1 unaware HIV-infected individual ranged from US$51 to US$2,072 across PWID sites and from US$189 to US$5,367 across MSM sites. The mean additional cost of identifying 1 unaware HCV-infected PWID was US$13 (site range: US$7-US$140). Limitations of the study include the exclusivity of study sites to India, lack of prior HIV/HCV diagnosis confirmation with clinic records, and lack of cost data from other case-finding approaches commonly used in India. In this study, RDS was able to rapidly identify at nominal cost a substantial number of unaware and viremic HIV-infected and HCV-infected individuals who were currently not being reached by existing programs and who were at high risk for transmission. Combining RDS (or other network-driven recruitment approaches) with strategies focused on linkage to care, particularly in high-burden settings, may be a viable option for achieving the 90-90-90 targets in key populations in resource-limited settings.

Understanding Suicide Attempts Among Gay Men From Their Self-perceived Causes.

PubMed

Wang, Jen; Plöderl, Martin; Häusermann, Michael; Weiss, Mitchell G

2015-07-01

Gay men are at higher risk of suicidality. This paper describes the causes of suicide attempts as perceived by the men themselves and analyzes their impact on severity and recidivism. Mental health surveys conducted among gay men in Geneva, Switzerland, from two probability-based time-space samples in 2007 and 2011, were merged to yield a combined sample N = 762. Suicide ideation, plans, and attempts were assessed, and respondents who had ever attempted suicide answered open questions about perceived causes which were coded and categorized for analysis within the framework of cultural epidemiology. In all, 16.7% of the respondents reported a suicide attempt in their lifetime (59.5% of them with multiple attempts). At their latest attempt, over two thirds asserted intent to die, and half required medical assistance. There was a wide variety of perceived causes, with most individuals reporting multiple causes and many of the most common causes cited at both the first and most recent subsequent attempts. Social/inter-personal problems constitute the most prominent category. Problems with love/relationship and accepting one's homosexuality figure consistently among the top three causes. Whereas the former tend to be associated with weaker intent to die, the latter are associated with the strongest intent to die and reported at multiple attempts. Problems with family are among the most common perceived causes at first attempt but not at the most recent subsequent attempt. Nevertheless, they tend to be related to the strongest intent to die and the greatest medical severity of all the perceived causes. Ten percent of men attempting suicide cited depression as a cause. Although it tended to be associated with weaker intent to die, depression was most likely to be reported at multiple attempts. Respondent-driven assessment yielded both common and idiosyncratic causes of suicide and their distinct effects. Some of these perceived causes are not prominent in the current literature, yet they have important implications for understanding risk and preventing suicide among gay men.

HIV prevention needs for men who have sex with men in Swaziland.

PubMed

Sithole, Bhekie

2017-12-01

Men who have sex with men (MSM) have a high HIV burden and also often face multiple other challenges accessing HIV services, including legal and social issues. Although Swaziland recently started responding with interventions for MSM, significant gaps still exist both in information and programming. This study aimed to explore the HIV prevention needs of MSM in Swaziland, including factors elevating their risks and vulnerabilities to HIV infection; to find out what HIV prevention strategies exist; and to determine how best to meet the prevention needs of MSM. A total of 50 men who reported anal sex with other men in the past 12 months were recruited through simple respondent driven sampling. They completed either a structured quantitative survey (n = 35) or participated in a semi-structured qualitative interview (n = 15). Both quantitative and qualitative findings indicated perceived and experienced stigma among MSM. This predominantly manifested as internalised stigma, which may lead to alcohol abuse and sexual risky behaviours. At least 83% (29/35) of the quantitative sample had been labelled with derogatory terms because of their sexual orientation, while 66% (23/35) had experienced being avoided. There was limited knowledge of risk practices: When asked, 54% (19/35) of quantitative respondents reported that vaginal and anal sex carry an equal risk of HIV infection. Participants also had little knowledge on new HIV prevention methods such as pre-exposure prophylaxis (PrEP) and rectal microbicides. MSM needs included safe spaces in form of drop-in centres and non-hostile HIV services. Although Swaziland recently started interventions for key populations, including MSM, there is still a general lack on information to inform managers and implementers on the HIV prevention needs of MSM in Swaziland. Such information is crucial for designers of official and HIV programmes. Research is needed to increase knowledge on the HIV prevention needs for key populations, including MSM.

Utilisation of a community-based health facility in a low-income urban community in Ibadan, Nigeria

PubMed Central

Asuzu, Michael C.

2015-01-01

Background Primary healthcare is established to ensure that people have access to health services through facilities located in their community. However, utilisation of health facilities in Nigeria remains low in many communities. Aim To assess the utilisation of community-based health facility (CBHF) amongst adults in Ibadan, Nigeria Settings A low-income community in Ibadan North West Local Government Area of Oyo State. Methods A cross-sectional survey was conducted using a simple random sampling technique to select one adult per household in all 586 houses in the community. A semi-structured interviewer-administered questionnaire was used to collect information on respondents' sociodemographic characteristics, knowledge and utilisation of the CBHF. Data analysis included descriptive statistics and association testing using the Chi-square test at p = 0.05. Results The mean age of the respondents was 46.5 ± 16.0 years; 46.0% were men and 81.0% married; 26% had no formal education and 38.0% had secondary-level education and above; traders constituted 52.0% of the sample; and 85.2% were of low socioeconomic standing; 90% had patronised the CBHF. The main reasons for non-utilisation were preference for general hospitals (13.8%) and self-medication (12.1%). Respondents who had secondary education and above, were in a higher socioeconomic class, who had good knowledge of the facility and were satisfied with care, utilised the CBHF three months significantly more than their counterparts prior to the study (p < 0.05). However, only satisfaction with care was found to be a significant predictor of utilisation of the CBHF. Conclusion The utilisation of the CBHF amongst adults in the study setting is high, driven mostly by satisfaction with the care received previously. Self-medication, promoted by uncontrolled access to drugs through pharmacies and patent medicine stores, threatens this high utilisation. PMID:26245600

Optimizing information technology to improve sexual health-care delivery: public and patient preferences.

PubMed

Ross, J D C; Copas, A; Stephenson, J; Fellows, L; Gilleran, G

2007-07-01

Information and communication technology (ICT) has the potential to improve the quality of care and efficiency in sexual health clinics, but its introduction requires input not only from health-care professionals and ICT specialists but also from service users and potential future users. In this study, views on ICT in relation to the delivery of sexual health services were assessed using a structured interview in two groups - a community sample of young people and a clinic sample of existing patients. In all, 542 community interviewees and 202 clinic patients participated. About 75% of respondents had access to the Internet and overall 60% reported that the self-collection of a sexual history on an electronic form was acceptable. Black Caribbean individuals had significantly less access to the Internet and a lower acceptance of electronic data collection. For booking an appointment, the majority of patients reported the telephone (community sample 93%, clinic sample 96%) or attending in person (community sample 77%, clinic sample 54%) to be acceptable, with a smaller proportion choosing email (community sample 10%, clinic sample 27%) or the Internet (community sample 7%, clinic sample 11%). Electronic booking was significantly less acceptable to Black Caribbean respondents. Although new technologies offer the opportunity to improve the quality of sexual health services, patient preferences and differences between groups in access to technology also need to be considered when services are reconfigured.

Kenyan female sex workers' use of female-controlled nonbarrier modern contraception: do they use condoms less consistently?

PubMed

Yam, Eileen A; Okal, Jerry; Musyoki, Helgar; Muraguri, Nicholas; Tun, Waimar; Sheehy, Meredith; Geibel, Scott

2016-03-01

To examine whether nonbarrier modern contraceptive use is associated with less consistent condom use among Kenyan female sex workers (FSWs). Researchers recruited 579 FSWs using respondent-driven sampling. We conducted multivariate logistic regression to examine the association between consistent condom use and female-controlled nonbarrier modern contraceptive use. A total of 98.8% reported using male condoms in the past month, and 64.6% reported using female-controlled nonbarrier modern contraception. In multivariate analysis, female-controlled nonbarrier modern contraceptive use was not associated with decreased condom use with clients or nonpaying partners. Consistency of condom use is not compromised when FSWs use available female-controlled nonbarrier modern contraception. FSWs should be encouraged to use condoms consistently, whether or not other methods are used simultaneously. Copyright © 2016 Elsevier Inc. All rights reserved.

TH-C-18A-09: Exam and Patient Parameters Affecting the DNA Damage Response Following CT Studies

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

Elgart, S; Adibi, A; Bostani, M

Purpose: To identify exam and patient parameters affecting the biological response to CT studies using in vivo and ex vivo blood samples. Methods: Blood samples were collected under IRB approval from 16 patients undergoing clinically-indicated CT exams. Blood was procured prior to, immediately after and 30minutes following irradiation. A sample of preexam blood was placed on the patient within the exam region for ex vivo analysis. Whole blood samples were fixed immediately following collection and stained for γH2AX to assess DNA damage response (DDR). Median fluorescence of treated samples was compared to non-irradiated control samples for each patient. Patients weremore » characterized by observed biological kinetic response: (a) fast — phosphorylation increased by 2minutes and fell by 30minutes, (b) slow — phosphorylation continued to increase to 30minutes and (c) none — little change was observed or irradiated samples fell below controls. Total dose values were normalized to exam time for an averaged dose-rate in dose/sec for each exam. Relationships between patient biological responses and patient and exam parameters were investigated. Results: A clearer dose response at 30minutes is observed for young patients (<61yoa; R2>0.5) compared to old patients (>61yoa; R{sup 2}<0.11). Fast responding patients were significantly younger than slow responding patients (p<0.05). Unlike in vivo samples, age did not significantly affect the patient response ex vivo. Additionally, fast responding patients received exams with significantly smaller dose-rate than slow responding patients (p<0.05). Conclusion: Age is a significant factor in the biological response suggesting that DDR may be more rapid in a younger population and slower as the population ages. Lack of an agerelated response ex vivo suggests a systemic response to radiation not present when irradiated outside the body. Dose-rate affects the biological response suggesting that patient response may be related to scan timing and dose delivery within an exam protocol. All authors receive(d) funding from a Master Research Agreement from Siemens Healthcare with UCLA Radiological Sciences.« less

Driven Boson Sampling.

PubMed

Barkhofen, Sonja; Bartley, Tim J; Sansoni, Linda; Kruse, Regina; Hamilton, Craig S; Jex, Igor; Silberhorn, Christine

2017-01-13

Sampling the distribution of bosons that have undergone a random unitary evolution is strongly believed to be a computationally hard problem. Key to outperforming classical simulations of this task is to increase both the number of input photons and the size of the network. We propose driven boson sampling, in which photons are input within the network itself, as a means to approach this goal. We show that the mean number of photons entering a boson sampling experiment can exceed one photon per input mode, while maintaining the required complexity, potentially leading to less stringent requirements on the input states for such experiments. When using heralded single-photon sources based on parametric down-conversion, this approach offers an ∼e-fold enhancement in the input state generation rate over scattershot boson sampling, reaching the scaling limit for such sources. This approach also offers a dramatic increase in the signal-to-noise ratio with respect to higher-order photon generation from such probabilistic sources, which removes the need for photon number resolution during the heralding process as the size of the system increases.

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

PubMed

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

2014-01-01

The purpose of this study is to examine the relationships among self-reported screening measures of attention deficit hyperactivity disorder (ADHD), other psychiatric problems, and driving-related outcomes in a provincially representative sample of adults 18 years and older living in the province of Ontario, Canada. The study examined the results of the Centre for Addictions and Mental Health (CAMH) Ontario Monitor, an ongoing repeated cross-sectional telephone survey of Ontario adults over a 2-year period. Measures included ADHD measures (Adult ADHD Self-Report Scale-V1.1 [ASRS-V1.1], previous ADHD diagnosis, ADHD medication use); psychiatric distress measures (General Health Questionnaire [GHQ12], use of pain, anxiety, and depression medication); antisocial behavior measure (The Antisocial Personality Disorder Scale from the Mini-International Neuropsychiatric Interview [APD]); substance use and abuse measures (alcohol, cannabis, and cocaine), Alcohol Use Disorders Identification Test (AUDIT), Alcohol, Smoking and Substance Involvement Screening Test (ASSIST), driving-related outcomes (driving after drinking, driving after cannabis use, street racing, collisions in past year), and sociodemographics (gender, age, vehicle-kilometers traveled). A total of 4,014 Ontario residents were sampled, of which 3,485 reported having a valid driver's license. Overall, 3.22% screened positive for ADHD symptoms on the ASRS-V1.1 screening tool. A greater percentage of those who screened positive were younger, reported previous ADHD diagnosis and medication use, distress, antisocial behavior, anti-anxiety and antidepressant medication use, substance use, and social problems compared to those who screened negative. However, there were no statistically significant differences between those who screened positive or negative for ADHD symptoms on self-reported driving after having 2 or more drinks in the previous hour; within an hour of using cannabis, marijuana, or hash; or in a street race or collision involvement as a driver in the past year. When a sequential regression was conducted to predict self-reported collisions, younger age and higher weekly kilometers driven showed higher odds of collision involvement, and the odds ratio for cannabis use ever approached statistical significance. This study is the first population-based study of a representative sample of adults 18 years and older living in Ontario, Canada. These results showed no relationship between the ADHD screen and collision when age, sex, and kilometers driven are controlled for. However, these analyses are based on self-report screeners and not psychiatric diagnoses and a limited sample of ADHD respondents. Thus, these results should be interpreted with caution.

Workplace violence. A focus on verbal abuse and intent to leave the organization.

PubMed

Sofield, Laura; Salmond, Susan W

2003-01-01

To describe the experience of verbal abuse in a large multihospital system and determine the relationship of verbal abuse with intent to leave the organization. Descriptive correlational design using mailed questionnaires. Randomized sample of 1000 nurses received questionnaire; 46% response rate, with a final useable sample of 461 surveys. Of the respondents, 91% had experienced verbal abuse in the past month. The physician was the most frequent source of verbal abuse, followed by patients, patient families, peers, supervisors, and subordinates. More than 50% of the sample did not feel competent in responding to verbal abuse. Amount of abuse and intent to leave were significantly related (r = .211, p < .01). Organizations must adopt zero-tolerance policies for professional verbal abuse. Education and coaching are needed to help nurses to improve their skills when responding to patient-to-nurse and professional-to-professional verbal abuse.

Some pain, no gain: experiences with the no-claim rebate in the Dutch health care system.

PubMed

Holland, J; Van Exel, N J A; Schut, F T; Brouwer, W B F

2009-10-01

To contain expenditures in an increasingly demand driven health care system, in 2005 a no-claim rebate was introduced in the Dutch health insurance system. Since demand-side cost sharing is a very controversial issue, the no-claim rebate was launched as a consumer friendly bonus system to reward prudent utilization of health services. Internationally, the introduction of a mandatory no-claim rebate in a social health insurance scheme is unprecedented. Consumers were entitled to an annual rebate of 255 eruos if no claims were made. During the year, all health care expenses except for GP visits and maternity care were deducted from the rebate until the rebate became zero. In this article, we discuss the rationale of the no-claim rebate and the available evidence of its effect. Using a questionnaire in a convenience sample, we examined people's knowledge, attitudes, and sensitivity to the incentive scheme. We find that only 4% of respondents stated that they would reduce consumption because of the no-claim rebate. Respondents also indicated that they were willing to accept a high loss of rebate in order to use a medical treatment. However, during the last month of the year many respondents seemed willing to postpone consumption until the next year in order to keep the rebate of the current year intact. A small majority of respondents considered the no-claim rebate to be unfair. Finally, we briefly discuss why in 2008 the no-claim rebate was replaced by a mandatory deductible.

Face-Likeness and Image Variability Drive Responses in Human Face-Selective Ventral Regions

PubMed Central

Davidenko, Nicolas; Remus, David A.; Grill-Spector, Kalanit

2012-01-01

The human ventral visual stream contains regions that respond selectively to faces over objects. However, it is unknown whether responses in these regions correlate with how face-like stimuli appear. Here, we use parameterized face silhouettes to manipulate the perceived face-likeness of stimuli and measure responses in face- and object-selective ventral regions with high-resolution fMRI. We first use “concentric hyper-sphere” (CH) sampling to define face silhouettes at different distances from the prototype face. Observers rate the stimuli as progressively more face-like the closer they are to the prototype face. Paradoxically, responses in both face- and object-selective regions decrease as face-likeness ratings increase. Because CH sampling produces blocks of stimuli whose variability is negatively correlated with face-likeness, this effect may be driven by more adaptation during high face-likeness (low-variability) blocks than during low face-likeness (high-variability) blocks. We tested this hypothesis by measuring responses to matched-variability (MV) blocks of stimuli with similar face-likeness ratings as with CH sampling. Critically, under MV sampling, we find a face-specific effect: responses in face-selective regions gradually increase with perceived face-likeness, but responses in object-selective regions are unchanged. Our studies provide novel evidence that face-selective responses correlate with the perceived face-likeness of stimuli, but this effect is revealed only when image variability is controlled across conditions. Finally, our data show that variability is a powerful factor that drives responses across the ventral stream. This indicates that controlling variability across conditions should be a critical tool in future neuroimaging studies of face and object representation. PMID:21823208

Sex Differences in HIV Prevalence, Behavioral Risks and Prevention Needs Among Anglophone and Francophone Sub-Saharan African Migrants Living in Rabat, Morocco.

PubMed

Johnston, Lisa; Oumzil, Hicham; El Rhilani, Houssine; Latifi, Amina; Bennani, Aziza; Alami, Kamal

2016-04-01

Morocco has experienced a dramatic increase of migration from sub-Sahara Africa during the past decade. Recently included among the most vulnerable populations cited in the Morocco National Strategic Plans on HIV/TB for 2012-2016, sub-Saharan Africa migrants living in an irregular administrative situation participated in a survey to provide baseline data about their socio-demographic, sexual and HIV testing behaviors and HIV and syphilis prevalence. Two surveys using respondent driven sampling were conducted in 2013 among males and females, ≥18 years, originating from sub-Saharan African countries and living and/or working in an irregular administrative situation in Rabat and residing at least 3 months in Morocco. Analysis was conducted to evaluate differences between the two samples and between females and males within each sample using the successive sampling estimator in RDS Analyst. Roughly 3 % of francophone and anglophone migrants were infected with HIV, whereas a statistically significantly higher percentage of francophone (2.8 %), compared to anglophone (0.3 %), migrants were infected with syphilis. Females were found to have HIV infection rates three times higher and past year sexually transmitted infection signs and symptoms more than two times higher than their male counterparts. Female migrants also had statistically significantly higher percentages of ever testing for HIV and HIV testing and receiving results in the past year compared to males. We found distinct and important differences between migrants depending on whether they come from francophone versus anglophone countries and whether they were male or female. Future research should continue to explore these differences, while policies and programs should note these differences to best allocate resources in providing social and health services to these populations.

IL-6 pathway-driven investigation of response to IL-6 receptor inhibition in rheumatoid arthritis

PubMed Central

Wang, Jianmei; Platt, Adam; Upmanyu, Ruchi; Germer, Søren; Lei, Guiyuan; Rabe, Christina; Benayed, Ryma; Kenwright, Andrew; Hemmings, Andrew; Martin, Mitchell; Harari, Olivier

2013-01-01

Objectives To determine whether heterogeneity in interleukin-6 (IL-6), IL-6 receptor and other components of the IL-6 signalling pathway/network, at the gene, transcript and protein levels, correlate with disease activity in patients with rheumatoid arthritis (RA) and with clinical response to tocilizumab. Design Biomarker samples and clinical data for five phase 3 trials of tocilizumab were analysed using serum (3751 samples), genotype (927 samples) and transcript (217 samples) analyses. Linear regression was then used to assess the association between these markers and either baseline disease activity or treatment response. Results Higher baseline serum IL-6 levels were significantly associated (p<0.0001) with higher baseline DAS28, erythrocyte sedimentation rate, C reactive protein and Health Assessment Questionnaire in patients whose responses to disease-modifying antirheumatic drugs (DMARD-IR) and to antitumour necrosis factor (aTNF-IR) were inadequate and patients who were naive/responders to methotrexate (MTX). Higher baseline serum IL-6 levels were also significantly associated with better clinical response to tocilizumab (versus placebo) measured by cDAS28 in the pooled DMARD-IR (p<0.0001) and MTX-naive populations (p=0.04). However, the association with treatment response was weak. A threefold difference in baseline IL-6 level corresponded to only a 0.17-unit difference in DAS28 at week 16. IL-6 pathway single nucleotide polymorphisms and RNA levels also were not strongly associated with treatment response. Conclusions Our analyses illustrate that the biological activity of a disease-associated molecular pathway may impact the benefit of a therapy targeting that pathway. However, the variation in pathway activity, as measured in blood, may not be a strong predictor. These data suggest that the major contribution to variability in clinical responsiveness to therapeutics in RA remains unknown. PMID:23959753

Using Facebook to Recruit Parents to Participate in a Family Program to Prevent Teen Drug Use.

PubMed

Oesterle, Sabrina; Epstein, Marina; Haggerty, Kevin P; Moreno, Megan A

2018-05-01

Despite strong evidence that family programs are effective in preventing adolescent substance use, recruiting parents to participate in such programs remains a persistent challenge. This study explored the feasibility of using Facebook to recruit parents of middle school students to a self-directed family program to prevent adolescent drug use. The study used paid Facebook ads aiming to recruit 100 parents in Washington and Colorado using marijuana- or parenting-focused messages. All ad-recruited parents were also invited to refer others in order to compare Facebook recruitment to web-based respondent-driven sampling. Despite offering a $15 incentive for each successfully referred participant, the majority of the screened (70.4%) and eligible (65.1%) parents were recruited through Facebook ads. Yet, eligibility and consent rates were significantly higher among referred (76.6 and 57.3%, respectively) than Facebook-recruited parents (60.0 and 36.6%, respectively). Click-through rates on Facebook were higher for marijuana-focused than parenting-focused ads (0.72 and 0.65%, respectively). The final sample (54% Facebook-recruited) consisted of 103 demographically homogeneous parents (female, educated, non-Hispanic White, and mostly from Washington). Although Facebook was an effective and efficient method to recruit parents to a study with equal to better cost-effectiveness than traditional recruitment strategies, the promise of social media to reach a diverse population was not realized. Additional approaches to Facebook recruitment are needed to reach diverse samples in real-world settings and increase public health impact of family programs.

Therapygenetics: anterior cingulate cortex-amygdala coupling is associated with 5-HTTLPR and treatment response in panic disorder with agoraphobia.

PubMed

Lueken, Ulrike; Straube, Benjamin; Wittchen, Hans-Ulrich; Konrad, Carsten; Ströhle, Andreas; Wittmann, André; Pfleiderer, Bettina; Arolt, Volker; Kircher, Tilo; Deckert, Jürgen; Reif, Andreas

2015-01-01

Variation in the 5'-flanking promoter region of the serotonin transporter gene SLC6A4, the 5-HTT-linked polymorphic region (5-HTTLPR) has been inconclusively associated with response to cognitive-behavioural therapy (CBT). As genomic functions are stronger related to neural than to behavioural markers, we investigated the association of treatment response, 5-HTTLPR and functional brain connectivity in patients with panic disorder with agoraphobia (PD/AG). Within the national research network PANIC-NET 231 PD/AG patients who provided genetic information underwent a manualized exposure-based CBT. A subset of 41 patients participated in a functional magnetic resonance imaging (fMRI) add-on study prior to treatment applying a differential fear conditioning task. Neither the treatment nor the reduced fMRI sample showed a direct effect of 5-HTTLPR on treatment response as defined by a reduction in the Hamilton Anxiety Scale score ≥50 % from baseline to post assessment. On a neural level, inhibitory anterior cingulate cortex (ACC)-amygdala coupling during fear conditioning that had previously been shown to characterize treatment response in this sample was driven by responders with the L/L genotype. Building upon conclusive evidence from basic and preclinical findings on the association of the 5-HTTLPR polymorphism with emotion regulation and related brain connectivity patterns, present findings translate these to a clinical sample of PD/AG patients and point towards a potential intermediate connectivity phenotype modulating response to exposure-based CBT.

Permissive norms and young adults' alcohol and marijuana use: the role of online communities.

PubMed

Stoddard, Sarah A; Bauermeister, Jose A; Gordon-Messer, Deborah; Johns, Michelle; Zimmerman, Marc A

2012-11-01

Young adults are increasingly interacting with their peer groups online through social networking sites. These online interactions may reinforce or escalate alcohol and other drug (AOD) use as a result of more frequent and continuous exposure to AOD promotive norms; however, the influence of young adults' virtual networks on AOD use remains untested. The purpose of this study was to examine the association between the presence of AOD use content in online social networking, perceived norms (online norms regarding AOD use and anticipated regret with AOD use postings), and alcohol and marijuana use in a sample of 18- to 24-year-olds. Using an adapted web version of respondent-driven sampling (webRDS), we recruited a sample of 18- to 24-year-olds (N = 3,448) in the United States. Using multivariate regression, we explored the relationship between past-30-day alcohol and marijuana use, online norms regarding AOD use, peer substance use, and online and offline peer support. Alcohol use was associated with more alcohol content online. Anticipated regret and online peer support were associated with less alcohol use. Anticipated regret was negatively associated with marijuana use. Peer AOD use was positively associated with both alcohol and marijuana use. Peers play an important role in young adult alcohol and marijuana use, whether online or in person. Our findings highlight the importance of promoting online network-based AOD prevention programs for young adults in the United States.

The impact of non-response bias due to sampling in public health studies: A comparison of voluntary versus mandatory recruitment in a Dutch national survey on adolescent health.

PubMed

Cheung, Kei Long; Ten Klooster, Peter M; Smit, Cees; de Vries, Hein; Pieterse, Marcel E

2017-03-23

In public health monitoring of young people it is critical to understand the effects of selective non-response, in particular when a controversial topic is involved like substance abuse or sexual behaviour. Research that is dependent upon voluntary subject participation is particularly vulnerable to sampling bias. As respondents whose participation is hardest to elicit on a voluntary basis are also more likely to report risk behaviour, this potentially leads to underestimation of risk factor prevalence. Inviting adolescents to participate in a home-sent postal survey is a typical voluntary recruitment strategy with high non-response, as opposed to mandatory participation during school time. This study examines the extent to which prevalence estimates of adolescent health-related characteristics are biased due to different sampling methods, and whether this also biases within-subject analyses. Cross-sectional datasets collected in 2011 in Twente and IJsselland, two similar and adjacent regions in the Netherlands, were used. In total, 9360 youngsters in a mandatory sample (Twente) and 1952 youngsters in a voluntary sample (IJsselland) participated in the study. To test whether the samples differed on health-related variables, we conducted both univariate and multivariable logistic regression analyses controlling for any demographic difference between the samples. Additional multivariable logistic regressions were conducted to examine moderating effects of sampling method on associations between health-related variables. As expected, females, older individuals, as well as individuals with higher education levels, were over-represented in the voluntary sample, compared to the mandatory sample. Respondents in the voluntary sample tended to smoke less, consume less alcohol (ever, lifetime, and past four weeks), have better mental health, have better subjective health status, have more positive school experiences and have less sexual intercourse than respondents in the mandatory sample. No moderating effects were found for sampling method on associations between variables. This is one of first studies to provide strong evidence that voluntary recruitment may lead to a strong non-response bias in health-related prevalence estimates in adolescents, as compared to mandatory recruitment. The resulting underestimation in prevalence of health behaviours and well-being measures appeared large, up to a four-fold lower proportion for self-reported alcohol consumption. Correlations between variables, though, appeared to be insensitive to sampling bias.

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--METALS IN DERMAL ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Dermal Wipes data set contains analytical results for measurements of up to 11 metals in 86 dermal wipe samples over 86 households. Each sample was collected from the primary respondent within each household. The sampling period occurred on the first day of the fi...

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--METALS IN URINE ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Urine data set contains analytical results for measurements of up to 7 metals in 86 urine samples over 86 households. Each sample was collected from the primary respondent within each household. The sample consists of the first morning void following the 24-hour d...

Impact of participant incentives and direct and snowball sampling on survey response rate in an ethnically diverse community: results from a pilot study of physical activity and the built environment.

PubMed

Perez, Daniel F; Nie, Jason X; Ardern, Chris I; Radhu, Natasha; Ritvo, Paul

2013-02-01

Community-wide efforts to encourage healthy behaviours must respond to the needs of existing neighbourhoods, especially those where low physical activity (PA) is associated with social, economic, and cultural challenges. This study reports on the effect of direct and snowball sampling strategies and financial incentive levels on the response rates of a built environment and PA survey in a predominately urban, low-SES new-immigrant community. Women residing in the Jane-Finch neighbourhood of Toronto, Ontario were selected to participate by quasi-random sampling, yielding a response rate of 41.5%. The survey completion rate per contact attempt increased 2-fold when incentives were increased from $10 to $20 and a further threefold following the increase from $20 to $30. Snowball sampled respondents were older, less likely to have full-time employment, and had lower educational attainment than directly sampled participants. With appropriate incentives, face-to-face contact, and snowball sampling, survey-based research is feasible within a low-SES, high minority population.

Acute stress symptoms during the second Lebanon war in a random sample of Israeli citizens.

PubMed

Cohen, Miri; Yahav, Rivka

2008-02-01

The aims of this study were to assess prevalence of acute stress disorder (ASD) and acute stress symptoms (ASS) in Israel during the second Lebanon war. A telephone survey was conducted in July 2006 of a random sample of 235 residents of northern Israel, who were subjected to missile attacks, and of central Israel, who were not subjected to missile attacks. Results indicate that ASS scores were higher in the northern respondents; 6.8% of the northern sample and 3.9% of the central sample met ASD criteria. Appearance of each symptom ranged from 15.4% for dissociative to 88.4% for reexperiencing, with significant differences between northern and central respondents only for reexperiencing and arousal. A low ASD rate and a moderate difference between areas subjected and not subjected to attack were found.

Testing the Merger Paradigm: X-ray Observations of Radio-Selected Sub-Galactic-Scale Binary AGNs

NASA Astrophysics Data System (ADS)

Fu, Hai

2016-09-01

Interactions play an important role in galaxy evolution. Strong gas inflows are expected in the process of gas-rich mergers, which may fuel intense black hole accretion and star formation. Sub-galactic-scale binary/dual AGNs thus offer elegant laboratories to study the merger-driven co-evolution phase. However, previous samples of kpc-scale binaries are small and heterogeneous. We have identified a flux-limited sample of kpc-scale binary AGNs uniformly from a wide-area high-resolution radio survey conducted by the VLA. Here we propose Chandra X-ray characterization of a subset of four radio-confirmed binary AGNs at z 0.1. Our goal is to compare their X-ray properties with those of matched control samples to test the merger-driven co-evolution paradigm.

Are Health State Valuations from the General Public Biased? A Test of Health State Reference Dependency Using Self-assessed Health and an Efficient Discrete Choice Experiment.

PubMed

Jonker, Marcel F; Attema, Arthur E; Donkers, Bas; Stolk, Elly A; Versteegh, Matthijs M

2017-12-01

Health state valuations of patients and non-patients are not the same, whereas health state values obtained from general population samples are a weighted average of both. The latter constitutes an often-overlooked source of bias. This study investigates the resulting bias and tests for the impact of reference dependency on health state valuations using an efficient discrete choice experiment administered to a Dutch nationally representative sample of 788 respondents. A Bayesian discrete choice experiment design consisting of eight sets of 24 (matched pairwise) choice tasks was developed, with each set providing full identification of the included parameters. Mixed logit models were used to estimate health state preferences with respondents' own health included as an additional predictor. Our results indicate that respondents with impaired health worse than or equal to the health state levels under evaluation have approximately 30% smaller health state decrements. This confirms that reference dependency can be observed in general population samples and affirms the relevance of prospect theory in health state valuations. At the same time, the limited number of respondents with severe health impairments does not appear to bias social tariffs as obtained from general population samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The impact of a community driven mass media campaign on the utilisation of maternal health care services in rural Malawi.

PubMed

Zamawe, Collins O F; Banda, Masford; Dube, Albert N

2016-01-27

Mass media is critical in disseminating public health information, improving health knowledge and changing health behaviours. However, most of the mass media public health interventions do not sufficiently engage the local people; they are externally determined. Due to this, very little is known about the effects of locally instigated mass media promotion. Therefore, the aim of this study was to examine the impact of a community driven mass media campaign called Phukusi la Moyo (tips of life) on the utilisation of maternal health care services. A community-based cross-sectional study involving 3825 women of reproductive age (15-49 years) was conducted in rural Malawi to evaluate the Phukusi la Moyo (PLM) campaign. To do this, we compared the utilisation of maternal health care services between women who were exposed to the PLM campaign and those who were not. Respondents were identified using a multistage cluster sampling method. This involved systematically selecting communities (clusters), households and respondents. Associations were examined using Pearson chi square test and a multivariable logistic regression model. The likelihood of using contraceptives (AOR = 1.61; 95% CI = 1.32-1.96), sleeping under mosquito bed-nets (AOR = 1.65; 95% CI = 1.39-1.97), utilising antenatal care services (AOR = 2.62; 95% CI = 1.45-4.73) and utilising postnatal care services (AOR = 1.59; CI = 1.29-1.95) were significantly higher among women who had exposure to the PLM campaign than those who did not. No significant association was found between health facility delivery and exposure to the PLM campaign. Women exposed to a community driven mass media campaign in rural Malawi were more likely to utilise maternal health care services than their unexposed counterparts. Since, the use of maternal health care services reduces the risk of maternal morbidity and mortality, community-led mass media could play a significant role towards improving maternal health outcomes in low-and-middle-income countries. Therefore, we recommend the use of locally driven mass media in disseminating public health information in limited resource settings.

Identifying Factors that Increase the Likelihood of Driving After Drinking among College Students

PubMed Central

LaBrie, Joseph W.; Kenney, Shannon R.; Mirza, Tehniat; Lac, Andrew

2012-01-01

Driving after drinking (DAD) is a serious public health concern found to be more common among college students than those of other age groups or same-aged non-college peers. The current study examined potential predictors of DAD among a dual-site sample of 3,753 (65% female, 58% Caucasian) college students. Results showed that 19.1% of respondents had driven after 3 or more drinks and 8.6% had driven after 5 or more drinks in the past three months. A logistic regression model showed that male status, fraternity or sorority affiliation, family history of alcohol abuse, medium or heavy drinking (as compared to light drinking), more approving self-attitudes towards DAD, and alcohol expectancies for sexual enhancement and risk/aggression, were independently associated with driving after drinking over and above covariates. These results extend the current understanding of this high risk drinking behavior in collegiate populations and provide implications for preventive strategies. Findings indicate that in addition to targeting at-risk subgroups, valuable directions for DAD-related interventions may include focusing on lowering both self-approval of DAD and alcohol-related expectancies, particularly those associated with risk/aggression and sexuality. PMID:21545868

Acute stress selectively reduces reward sensitivity

PubMed Central

Berghorst, Lisa H.; Bogdan, Ryan; Frank, Michael J.; Pizzagalli, Diego A.

2013-01-01

Stress may promote the onset of psychopathology by disrupting reward processing. However, the extent to which stress impairs reward processing, rather than incentive processing more generally, is unclear. To evaluate the specificity of stress-induced reward processing disruption, 100 psychiatrically healthy females were administered a probabilistic stimulus selection task (PSST) that enabled comparison of sensitivity to reward-driven (Go) and punishment-driven (NoGo) learning under either “no stress” or “stress” (threat-of-shock) conditions. Cortisol samples and self-report measures were collected. Contrary to hypotheses, the groups did not differ significantly in task performance or cortisol reactivity. However, further analyses focusing only on individuals under “stress” who were high responders with regard to both cortisol reactivity and self-reported negative affect revealed reduced reward sensitivity relative to individuals tested in the “no stress” condition; importantly, these deficits were reward-specific. Overall, findings provide preliminary evidence that stress-reactive individuals show diminished sensitivity to reward, but not punishment, under stress. While such results highlight the possibility that stress-induced anhedonia might be an important mechanism linking stress to affective disorders, future studies are necessary to confirm this conjecture. PMID:23596406

Managing urban runoff in residential neighborhoods: Nitrogen and phosphorus in lawn irrigation driven runoff.

PubMed

Toor, Gurpal S; Occhipinti, Marti L; Yang, Yun-Ya; Majcherek, Tammy; Haver, Darren; Oki, Lorence

2017-01-01

Sources and mechanisms of nutrient transport in lawn irrigation driven surface runoff are largely unknown. We investigated the transport of nitrogen (N) and phosphorus (P) in lawn irrigation driven surface runoff from a residential neighborhood (28 ha) of 56% impervious and 44% pervious areas. Pervious areas encompassing turfgrass (lawns) in the neighborhood were irrigated with the reclaimed water in common areas during the evening to late night and with the municipal water in homeowner's lawns during the morning. The stormwater outlet pipe draining the residential neighborhood was instrumented with a flow meter and Hach autosampler. Water samples were collected every 1-h and triple composite samples were obtained at 3-h intervals during an intensive sampling period of 1-week. Mean concentrations, over 56 sampling events, of total N (TN) and total P (TP) in surface runoff at the outlet pipe were 10.9±6.34 and 1.3±1.03 mg L-1, respectively. Of TN, the proportion of nitrate-N was 58% and other-N was 42%, whereas of TP, orthophosphate-P was 75% and other-P was 25%. Flow and nutrient (N and P) concentrations were lowest from 6:00 a.m. to noon, which corresponded with the use of municipal water and highest from 6:00 p.m. to midnight, which corresponded with the use of reclaimed water. This data suggests that N and P originating in lawn irrigation driven surface runoff from residential catchments is an important contributor of nutrients in surface waters.

Managing urban runoff in residential neighborhoods: Nitrogen and phosphorus in lawn irrigation driven runoff

PubMed Central

Occhipinti, Marti L.; Yang, Yun-Ya; Majcherek, Tammy; Haver, Darren; Oki, Lorence

2017-01-01

Sources and mechanisms of nutrient transport in lawn irrigation driven surface runoff are largely unknown. We investigated the transport of nitrogen (N) and phosphorus (P) in lawn irrigation driven surface runoff from a residential neighborhood (28 ha) of 56% impervious and 44% pervious areas. Pervious areas encompassing turfgrass (lawns) in the neighborhood were irrigated with the reclaimed water in common areas during the evening to late night and with the municipal water in homeowner’s lawns during the morning. The stormwater outlet pipe draining the residential neighborhood was instrumented with a flow meter and Hach autosampler. Water samples were collected every 1-h and triple composite samples were obtained at 3-h intervals during an intensive sampling period of 1-week. Mean concentrations, over 56 sampling events, of total N (TN) and total P (TP) in surface runoff at the outlet pipe were 10.9±6.34 and 1.3±1.03 mg L–1, respectively. Of TN, the proportion of nitrate–N was 58% and other–N was 42%, whereas of TP, orthophosphate–P was 75% and other–P was 25%. Flow and nutrient (N and P) concentrations were lowest from 6:00 a.m. to noon, which corresponded with the use of municipal water and highest from 6:00 p.m. to midnight, which corresponded with the use of reclaimed water. This data suggests that N and P originating in lawn irrigation driven surface runoff from residential catchments is an important contributor of nutrients in surface waters. PMID:28604811

Mechanochemistry for shock wave energy dissipation

NASA Astrophysics Data System (ADS)

Shaw, William L.; Ren, Yi; Moore, Jeffrey S.; Dlott, Dana D.

2017-01-01

Using a laser-driven flyer-plate apparatus to launch 75 μm thick Al flyers up to 2.8 km/s, we developed a technique for detecting the attenuation of shock waves by mechanically-driven chemical reactions. The attenuating sample was spread on an ultrathin Au mirror deposited onto a glass window having a known Hugoniot. As shock energy exited the sample and passed through the mirror, into the glass, photonic Doppler velocimetry monitored the velocity profile of the ultrathin mirror. Knowing the window Hugoniot, the velocity profile could be quantitatively converted into a shock energy flux or fluence. The flux gave the temporal profile of the shock front, and showed how the shock front was reshaped by passing through the dissipative medium. The fluence, the time-integrated flux, showed how much shock energy was transmitted through the sample. Samples consisted of microgram quantities of carefully engineered organic compounds selected for their potential to undergo negative-volume chemistry. Post mortem analytical methods were used to confirm that shock dissipation was associated with shock-induced chemical reactions.

Importance sampling large deviations in nonequilibrium steady states. I.

PubMed

Ray, Ushnish; Chan, Garnet Kin-Lic; Limmer, David T

2018-03-28

Large deviation functions contain information on the stability and response of systems driven into nonequilibrium steady states and in such a way are similar to free energies for systems at equilibrium. As with equilibrium free energies, evaluating large deviation functions numerically for all but the simplest systems is difficult because by construction they depend on exponentially rare events. In this first paper of a series, we evaluate different trajectory-based sampling methods capable of computing large deviation functions of time integrated observables within nonequilibrium steady states. We illustrate some convergence criteria and best practices using a number of different models, including a biased Brownian walker, a driven lattice gas, and a model of self-assembly. We show how two popular methods for sampling trajectory ensembles, transition path sampling and diffusion Monte Carlo, suffer from exponentially diverging correlations in trajectory space as a function of the bias parameter when estimating large deviation functions. Improving the efficiencies of these algorithms requires introducing guiding functions for the trajectories.

Importance sampling large deviations in nonequilibrium steady states. I

NASA Astrophysics Data System (ADS)

Ray, Ushnish; Chan, Garnet Kin-Lic; Limmer, David T.

2018-03-01

Large deviation functions contain information on the stability and response of systems driven into nonequilibrium steady states and in such a way are similar to free energies for systems at equilibrium. As with equilibrium free energies, evaluating large deviation functions numerically for all but the simplest systems is difficult because by construction they depend on exponentially rare events. In this first paper of a series, we evaluate different trajectory-based sampling methods capable of computing large deviation functions of time integrated observables within nonequilibrium steady states. We illustrate some convergence criteria and best practices using a number of different models, including a biased Brownian walker, a driven lattice gas, and a model of self-assembly. We show how two popular methods for sampling trajectory ensembles, transition path sampling and diffusion Monte Carlo, suffer from exponentially diverging correlations in trajectory space as a function of the bias parameter when estimating large deviation functions. Improving the efficiencies of these algorithms requires introducing guiding functions for the trajectories.

Religiousness and mood in the last week of life: an explorative approach based on after-death proxy interviews.

PubMed

Braam, Arjan W; Klinkenberg, Marianne; Deeg, Dorly J H

2011-01-01

Although religiousness may, to a certain extent, be expected to alleviate emotional suffering in the last week of life, some religious beliefs might also provoke emotional distress. For the current study, after-death interviews with proxy respondents of deceased sample members of the Longitudinal Aging Study Amsterdam provided information on depressive mood and anxiety in the last week of life, as well as on the presence of a sense of peace at the approaching end of life. Proxy respondents also were asked about serious physical symptoms in the last week of life of the respondent, the respondent's cognitive decline, and their estimate of the salience of religion for the sample member. Other characteristics were derived from the last interviews with the sample members when still alive: depressive symptoms, chronic diseases, religious affiliation, church attendance, belief in Heaven, belief in Hell, and salience of religion. None of the characteristics of religiousness was significantly associated with depressive mood or anxiety, as estimated by the proxy respondent. A sense of peace, however, was predicted by higher church attendance, belief in Hell (among church-members), and the proxy's estimate of the salience of religion. It can be concluded that religiousness did not affect depressive mood or anxiety in the last week of life in the current sample. It is possible that religiousness supports a sense of peace, which may be a more-existential facet of mood and is discussed as relevant in the last phase of life and in palliative care.

The importance of self-management in the prevention and treatment of excessive weight and obesity.

PubMed

Tóthová, Valérie; Bártlová, Sylva; Šedová, Lenka; Olišarová, Věra; Prokešová, Radka; Adámkova, Věra; Mauritzová, Ilona; Trešlová, Marie; Chloubová, Ivana; Mikšová, Zdeňka

2015-01-01

The aim of this research into 'self-management' was to determine to what extent respondents were aware of their status as overweight or obese. For respondents who indicated that they were overweight or obese, the goal was to determine whether they tried to lose weight, what steps they took to control their, and what specific methods they used. Information was collected using semi-structured interviews from May 31, 2014, to January 30, 2015. Data processing was performed using statistical analysis of the social data SASDM 01/04/10 software. The total study group consisted of 600 respondents, including 302 from the Roma minority, and 298 from the non-Roma majority population (control group). Respondents were selected specifically from South Bohemia Region of the Czech Republic. The sample from the Roma minority was constructed using the snowball method (Snowball Sampling). The control sample of non-Roma was selected through quota sampling. The results indicate that the respondents from both the Roma minority and the non-Roma control group generally recognized when they were overweight or obese, or they were aware of it to a much lesser extent than objective indicators revealed. More than two thirds of the respondents who admitted they were overweight or obese (N = 143) reported that they had suffered from overweight or obesity since they were young adults. Significantly more members of the majority population had tried to lose weight using self-management, whereas the level of effort was significantly less among members of the Roma minority (P = 0). Nevertheless, Roma respondents significantly more often reported (P < 0.01) that they had agreed on a specific weight loss plan with a doctor. The results of our research show that in the context of prevention, it is important to promote self-managed skills, habits and other characteristics that can play an important role in the prevention and treatment of obesity and overweight.

Using the animal to the last bit: Consumer preferences for different beef cuts.

PubMed

Scozzafava, Gabriele; Corsi, Armando Maria; Casini, Leonardo; Contini, Caterina; Loose, Simone Mueller

2016-01-01

Meat is expensive to produce, making it is essential to understand the importance consumers pay to different meat cuts. Previous research on consumers' meat choices has mainly focused on meat species, while consumer preferences for meat cuts has so far only received limited interest. The aim of this study is to shed some light into this relatively unexplored area by answering four research questions. First, this study intends to show the relative importance meat cuts play in relation to other extrinsic product attributes. Secondly, this paper looks into differences in choice criteria between regular and special occasions. Third, consumer segments that differ in their preferences and beef purchase are identified, and, finally, the meat purchase portfolios of these segments are revealed. A stated preference methodology of a discrete choice experiment with cut-specific prices covering several meat cuts simultaneously is proposed to answer the research questions. The sample consists of 1500 respondents representative of the Italian population in terms of age, gender and geographic location The results shows that meat cut is the most important factor when choosing bovine meat followed by quality certification (origin), production technique, the type of breed and price. In terms of consumption occasions, we observe significantly lower price sensitivity for marbled steaks and cutlets for special occasions compared to normal occasions. Segmentation analysis shows that while the choices of two segments (comprising about 40% of the sample) are mostly driven by extrinsic product attributes, the remaining segments are mostly driven by meat cuts. These varying preferences are also reflected in the purchase portfolios of the different segments, while less variability is detected from a socio-demographic perspective. Copyright © 2015 Elsevier Ltd. All rights reserved.

Experiments on the Effects of Confining Pressure During Reaction-Driven Cracking

NASA Astrophysics Data System (ADS)

Skarbek, R. M.; Savage, H. M.; Kelemen, P. B.; Lambart, S.; Robinson, B.

2016-12-01

Cracking caused by reaction-driven volume increase is an important process in many geological settings. In particular, the interaction of brittle rocks with reactive fluids can create fractures that modify the permeability and reactive surface area, leading to a large variety of feedbacks. The conditions controlling reaction-driven cracking are poorly understood, especially at geologically relevant confining pressures. We conducted two sets of experiments to study the effects of confining pressure on cracking during the formation of gypsum from anhydrite CaSO4 + 2H2O = CaSO4•2H2O, and portlandite from calcium oxide CaO + H2O = Ca(OH)2. In the first set of experiments, we cold-pressed CaSO4, or CaO powder to form cylinders. Samples were confined in steel, and compressed with an axial load of 0.1 to 4 MPa. Water was allowed to infiltrate the initially unsaturated samples through the bottom face via capillary and Darcian flow across a micro-porous frit. The height of the sample was recorded during the experiment, and serves as a measure of volume change due to the hydration reaction. We also recorded acoustic emissions (AEs) using piezoelectric transducers (PZTs), to serve as a measure of cracking during an experiment. Experiments were stopped when the recorded volume change reached 80% - 100% of the stoichiometrically calculated volume change of the reaction. In a second set of experiments, we pressed CaSO4 powder to form cylinders 8.9 cm in length and 3.5 cm in diameter for testing in a tri-axial press with ports for fluid input and output, across the top and bottom faces of the sample. The tri-axial experiments were set up to investigate the reaction-driven cracking process for a range of confining pressures. Cracking during experiments was monitored using strain gauges and PZTs attached to the sample. We measured permeability during experiments by imposing a fluid pressure gradient across the sample. These experiments elucidate the role of cracking caused by crystallization pressure in many important hydration reactions.

Optimized Routing of Intelligent, Mobile Sensors for Dynamic, Data-Driven Sampling

DTIC Science & Technology

2016-09-27

nonstationary random process that requires nonuniform sampling. The ap- proach incorporates complementary representations of an unknown process: the first...lookup table as follows. A uniform grid is created in the r-domain and mapped to the R-domain, which produces a nonuniform grid of locations in the R...vehicle coverage algorithm that invokes the coor- dinate transformation from the previous section to generate nonuniform sampling trajectories [54]. We

Three-dimensional structural representation of the sleep-wake adaptability.

PubMed

Putilov, Arcady A

2016-01-01

Various characteristics of the sleep-wake cycle can determine the success or failure of individual adjustment to certain temporal conditions of the today's society. However, it remains to be explored how many such characteristics can be self-assessed and how they are inter-related one to another. The aim of the present report was to apply a three-dimensional structural representation of the sleep-wake adaptability in the form of "rugby cake" (scalene or triaxial ellipsoid) to explain the results of analysis of the pattern of correlations of the responses to the initial 320-item list of a new inventory with scores on the six scales designed for multidimensional self-assessment of the sleep-wake adaptability (Morning and Evening Lateness, Anytime and Nighttime Sleepability, and Anytime and Daytime Wakeability). The results obtained for sample consisting of 149 respondents were confirmed by the results of similar analysis of earlier collected responses of 139 respondents to the same list of 320 items and responses of 1213 respondents to the 72 items of one of the earlier established questionnaire tools. Empirical evidence was provided in support of the model-driven prediction of the possibility to identify items linked to as many as 36 narrow (6 core and 30 mixed) adaptabilities of the sleep-wake cycle. The results enabled the selection of 168 items for self-assessment of all these adaptabilities predicted by the rugby cake model.

Analogical reasoning in amazons.

PubMed

Obozova, Tanya; Smirnova, Anna; Zorina, Zoya; Wasserman, Edward

2015-11-01

Two juvenile orange-winged amazons (Amazona amazonica) were initially trained to match visual stimuli by color, shape, and number of items, but not by size. After learning these three identity matching-to-sample tasks, the parrots transferred discriminative responding to new stimuli from the same categories that had been used in training (other colors, shapes, and numbers of items) as well as to stimuli from a different category (stimuli varying in size). In the critical testing phase, both parrots exhibited reliable relational matching-to-sample (RMTS) behavior, suggesting that they perceived and compared the relationship between objects in the sample stimulus pair to the relationship between objects in the comparison stimulus pairs, even though no physical matches were possible between items in the sample and comparison pairs. The parrots spontaneously exhibited this higher-order relational responding without having ever before been trained on RMTS tasks, therefore joining apes and crows in displaying this abstract cognitive behavior.

Canine scent detection and microbial source tracking of human waste contamination in storm drains.

PubMed

Van De Werfhorst, Laurie C; Murray, Jill L S; Reynolds, Scott; Reynolds, Karen; Holden, Patricia A

2014-06-01

Human fecal contamination of surface waters and drains is difficult to diagnose. DNA-based and chemical analyses of water samples can be used to specifically quantify human waste contamination, but their expense precludes routine use. We evaluated canine scent tracking, using two dogs trained to respond to the scent of municipal wastewater, as a field approach for surveying human fecal contamination. Fecal indicator bacteria, as well as DNA-based and chemical markers of human waste, were analyzed in waters sampled from canine scent-evaluated sites (urban storm drains and creeks). In the field, the dogs responded positively (70% and 100%) at sites for which sampled waters were then confirmed as contaminated with human waste. When both dogs indicated a negative response, human waste markers were absent. Overall, canine scent tracking appears useful for prioritizing sampling sites for which DNA-based and similarly expensive assays can confirm and quantify human waste contamination.

Concurrent sexual partnerships among men who have sex with men in Shenzhen, China.

PubMed

Ha, Toan H; Liu, Hongjie; Liu, Hui; Cai, Yumao; Feng, Tiejian

2010-08-01

The HIV epidemic spreads among men who have sex with men (MSM) in China. The objective of this study was to examine and compare HIV/AIDS knowledge and sexual risk for HIV between MSM who engaged in concurrent sexual partnerships and MSM who did not. A cross-sectional study using respondent driven sampling was conducted among 351 MSM in Shenzhen, China. About half (49%) of respondents reported having concurrent sexual partnerships during the past 6 months. Among MSM with concurrent sexual partnerships, 62% had only male partners and 38% had both male and female partners. The proportion of inconsistent condom use was 42% among MSM with concurrent partners and 30% among MSM without. These 2 groups reported a similar level of self-perceived risk for HIV. Compared to MSM without concurrent sexual partners, those with such partners were more likely to work in entertainment venues and had a lower level of HIV/AIDS knowledge. The large number of MSM engaging in concurrent sexual partnerships and the high prevalence of bisexuality could accelerate the spread of HIV to the general population unless effective HIV interventions for MSM are implemented in China.

Homophobia and racism experienced by Latino men who have sex with men in the United States: correlates of exposure and associations with HIV risk behaviors.

PubMed

Mizuno, Yuko; Borkowf, Craig; Millett, Gregorio A; Bingham, Trista; Ayala, George; Stueve, Ann

2012-04-01

Using cross-sectional data collected from 1081 Latino men who have sex with men (MSM) recruited with respondent-driven sampling (RDS) techniques from Los Angeles and New York, we examined the extent to which Latino MSM reported exposure to social discrimination (i.e., experienced both homophobia and racism, homophobia only, racism only, or neither homophobia nor racism). More than 40% of respondents experienced both homophobia and racism in the past 12 months. Los Angeles participants, those with lower income, and those who reported being HIV-positive were more likely to report experiencing both types of social discrimination. Adjusting for potential confounders, men exposed to both homophobia and racism were more likely than men exposed to neither form of discrimination to report unprotected receptive anal intercourse with a casual sex partner (AOR = 1.92, 95% CI, 1.18-3.24) and binge drinking (AOR = 1.42, 95% CI, 1.02-1.98). Our findings suggest the presence of a syndemic of adverse social experiences and call for more intervention research to address both homophobia and racism experienced among Latino MSM in the United States.

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

PubMed

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.

Laser-driven shock experiments on precompressed water: Implications for "icy" giant planets.

PubMed

Lee, Kanani K M; Benedetti, L Robin; Jeanloz, Raymond; Celliers, Peter M; Eggert, Jon H; Hicks, Damien G; Moon, Stephen J; Mackinnon, Andrew; Da Silva, Luis B; Bradley, David K; Unites, Walter; Collins, Gilbert W; Henry, Emeric; Koenig, Michel; Benuzzi-Mounaix, Alessandra; Pasley, John; Neely, David

2006-07-07

Laser-driven shock compression of samples precompressed to 1 GPa produces high-pressure-temperature conditions inducing two significant changes in the optical properties of water: the onset of opacity followed by enhanced reflectivity in the initially transparent water. The onset of reflectivity at infrared wavelengths can be interpreted as a semiconductor<-->electronic conductor transition in water, and is found at pressures above approximately 130 GPa for single-shocked samples precompressed to 1 GPa. Our results indicate that conductivity in the deep interior of "icy" giant planets is greater than realized previously because of an additional contribution from electrons.

Sample push-out fixture

DOEpatents

Biernat, John L.

2002-11-05

This invention generally relates to the remote removal of pelletized samples from cylindrical containment capsules. V-blocks are used to receive the samples and provide guidance to push out rods. Stainless steel liners fit into the v-channels on the v-blocks which permits them to be remotely removed and replaced or cleaned to prevent cross contamination between capsules and samples. A capsule holder securely holds the capsule while allowing manual up/down and in/out movement to align each sample hole with the v-blocks. Both end sections contain identical v-blocks; one that guides the drive out screw and rods or manual push out rods and the other to receive the samples as they are driven out of the capsule.

Attitudes towards smoking restrictions and tobacco advertisement bans in Georgia.

PubMed

Bakhturidze, George D; Mittelmark, Maurice B; Aarø, Leif E; Peikrishvili, Nana T

2013-11-25

This study aims to provide data on a public level of support for restricting smoking in public places and banning tobacco advertisements. A nationally representative multistage sampling design, with sampling strata defined by region (sampling quotas proportional to size) and substrata defined by urban/rural and mountainous/lowland settlement, within which census enumeration districts were randomly sampled, within which households were randomly sampled, within which a randomly selected respondent was interviewed. The country of Georgia, population 4.7 million, located in the Caucasus region of Eurasia. One household member aged between 13 and 70 was selected as interviewee. In households with more than one age-eligible person, selection was carried out at random. Of 1588 persons selected, 14 refused to participate and interviews were conducted with 915 women and 659 men. Respondents were interviewed about their level of agreement with eight possible smoking restrictions/bans, used to calculate a single dichotomous (agree/do not agree) opinion indicator. The level of agreement with restrictions was analysed in bivariate and multivariate analyses by age, gender, education, income and tobacco use status. Overall, 84.9% of respondents indicated support for smoking restrictions and tobacco advertisement bans. In all demographic segments, including tobacco users, the majority of respondents indicated agreement with restrictions, ranging from a low of 51% in the 13-25 age group to a high of 98% in the 56-70 age group. Logistic regression with all demographic variables entered showed that agreement with restrictions was higher with age, and was significantly higher among never smokers as compared to daily smokers. Georgian public opinion is normatively supportive of more stringent tobacco-control measures in the form of smoking restrictions and tobacco advertisement bans.

DHEA metabolism to the neurosteroid androsterone: a possible mechanism of DHEA's antidepressant action.

PubMed

Ben Dor, Rivka; Marx, Christine E; Shampine, Lawrence J; Rubinow, David R; Schmidt, Peter J

2015-09-01

Alterations in neurosteroid secretion have been implicated in the efficacy of antidepressants. In a previous study, the adrenal androgen DHEA, a precursor of the neurosteroid androsterone, produced antidepressant and libido-enhancing effects in patients with midlife depression. To investigate the mechanisms underlying DHEA's behavioral effects in this same patient group, we examined plasma levels of four additional neurosteroids implicated in the regulation of affective behavior. Blood samples were assayed for neurosteroids in men (n = 13) and women (n = 10) with midlife depression who previously participated in a crossover study in which DHEA and placebo were administered for 6 weeks each. Depression severity was measured by the Center for Epidemiologic Studies Depression Scale (CES-D). Plasma levels of androsterone (ADT), allopregnanolone, pregnanolone, and pregnenolone were measured by GC-MS at baseline and week 6 of each treatment phase. Data were analyzed with repeated measures analysis of variance (ANOVA-R) and Bonferroni t tests. ADT levels (but not allopregnanolone, pregnanolone, and pregnenolone) increased after DHEA but not after placebo (F 2,42 = 3.3, p < 0.05). Post-DHEA ADT levels were higher in women than men [t 63 = 2.9, p < 0.05]. However, in both men and women who met criteria for clinical response on the CES-D, baseline ADT levels significantly increased post-DHEA, and the magnitude of the ADT increase post-DHEA treatment was similar in men and women. Consequently, it was the non-responders who accounted for the sex difference in post-DHEA plasma ADT levels, a difference that was driven by values in two women (the only female non-responders). The small sample size notwithstanding, these data emphasize the potential behavioral relevance of ADT in humans, which may include contribution to the antidepressant effects of DHEA.

Community-Based Assessment to Inform a Chlamydia Screening Program for Women in a Rural American Indian Community

PubMed Central

Smartlowit-Briggs, Lucy; Pearson, Cynthia; Whitefoot, Patricia; Altamirano, Bianca N.; Womack, Michelle; Bastin, Marie; Dombrowski, Julia C.

2017-01-01

Background Rates of chlamydial infection in American Indian/Alaska Native women in the United States are approximately 4-fold those in non-Hispanic white women. We conducted a community-based survey of self-identified American Indian/Alaska Native women 14 to 25 years of age on a reservation in the Northwestern United States to inform a chlamydia screening strategy. Methods The anonymous survey assessed respondents’ knowledge, perceptions, and preferences related to chlamydia screening, results receipt, and partner notification. We recruited women using respondent-driven sampling, school-based sampling, and direct recruitment through social media and fliers. Participants in schools completed the survey as a paper-based, self-administered survey. Other participants could complete the survey in person, by phone as an interviewer-administered survey, or online. Results We recruited 162 participants, most in schools (n = 83; 51%) or by peer referral (n = 55; 34%). Only 1 woman completed the survey online. Thirty-one respondents (19%) reported a history of an unplanned first pregnancy, and 19 (12%) reported a history of a diagnosed sexually transmitted disease. Most women (n = 98; 63%) recognized the potential impact of Chlamydia trachomatis on fertility. The preferred site for chlamydia screening was the Indian Health Service Clinic (n = 114; 70%), but 79 women (41%) would accept a C. trachomatis test at a nonclinical testing site. Of the 56 women (35%) who would accept home testing, most preferred to get the test kit from a clinic. Conclusions Our results suggest that Indian Health Service efforts to increase chlamydia screening in the clinic and through outreach may be more successful than promotion of home testing in this population. PMID:27196261

What are people looking for when they Google "self-abortion"?

PubMed

Jerman, Jenna; Onda, Tsuyoshi; Jones, Rachel K

2018-06-01

To examine the motivations and circumstances of individuals seeking information about self-abortion on the Internet. We identified 26 terms that we anticipated someone might use to find information about self-abortion on the internet. Users who entered these terms into the Google search engine were provided with a link to our survey via Google AdWords. We fielded the survey over a 32-day period; users were eligible if accessing the survey from a US-based device. We examined demographic characteristics of the sample, reasons for searching for information on self-abortion, knowledge of the legality of abortion and of nearby providers, and top performing keywords. Our Google AdWords campaign containing the survey link was shown approximately 210,000 times, and clicked 9,800 times; 1,235 respondents completed the survey. The vast majority of the sample was female (96%), and 41% were minors. Almost three-quarters (73%) indicated that they were searching for information because they were pregnant and did not or may not want to be. Eleven percent had ever attempted to self-abort. One-third of respondents did not know if abortion was legal in their state of residence, and knowledge of legality did not differ by age. There is interest in learning more about self-abortion on the Internet. Our findings suggest that, among those who participated in our survey, online searches for information on self-abortion may be driven by adolescents and young adults facing an unintended pregnancy. Young women, in particular, may have an unmet need for information about safe and accessible abortion options. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

New evidence on the HIV epidemic in Libya: why countries must implement prevention programs among people who inject drugs.

PubMed

Mirzoyan, Lusine; Berendes, Sima; Jeffery, Caroline; Thomson, Joanna; Ben Othman, Hussain; Danon, Leon; Turki, Abdullah A; Saffialden, Rabea; Valadez, Joseph J

2013-04-15

Libya had one of the world's largest nosocomial HIV outbreaks in the late 1990 s leading to the detention of 6 foreign medical workers. They were released in 2007 after the Libyan Government and the European Union agreed to humanitarian cooperation that included the development of Libya's first National HIV Strategy and the research reported in this article. Despite the absence of sound evidence on the status and dynamics of Libya's HIV epidemic, some officials posited that injecting drug use was the main mode of transmission. We therefore sought to assess HIV prevalence and related risk factors among people who inject drugs (PWID) in Tripoli. We conducted a cross-sectional survey among 328 PWID in Tripoli using respondent-driven sampling. We collected behavioral data and blood samples for HIV, hepatitis C virus, and hepatitis B virus testing. We estimate an HIV prevalence of 87%, hepatitis C virus prevalence of 94%, and hepatitis B virus prevalence of 5%. We detected injecting drug use-related and sexual risk factors in the context of poor access to comprehensive services for HIV prevention and mitigation. For example, most respondents (85%) reported having shared needles. In this first biobehavioral survey among PWID in Libya, we detected one of the highest (or even the highest) levels of HIV infection worldwide in the absence of a comprehensive harm-reduction program. There is an urgent need to implement an effective National HIV Strategy informed by the results of this research, especially because recent military events and related sociopolitical disruption and migration might lead to a further expansion of the epidemic.

What are people looking for when they Google “self-abortion”?

PubMed Central

Jerman, Jenna; Onda, Tsuyoshi; Jones, Rachel K.

2018-01-01

Objective To examine the motivations and circumstances of individuals seeking information about self-abortion on the Internet. Study design We identified 26 terms that we anticipated someone might use to find information about self-abortion on the internet. Users who entered these terms into the Google search engine were provided with a link to our survey via Google AdWords. We fielded the survey over a 32-day period; users were eligible if accessing the survey from a US-based device. We examined demographic characteristics of the sample, reasons for searching for information on self-abortion, knowledge of the legality of abortion and of nearby providers, and top performing keywords. Results Our Google AdWords campaign containing the survey link was shown approximately 210,000 times, and clicked 9,800 times; 1,235 respondents completed the survey. The vast majority of the sample was female (96%), and 41% were minors. Almost three-quarters (73%) indicated that they were searching for information because they were pregnant and did not or may not want to be. Eleven percent had ever attempted to self-abort. One-third of respondents did not know if abortion was legal in their state of residence, and knowledge of legality did not differ by age. Conclusions There is interest in learning more about self-abortion on the Internet. Our findings suggest that, among those who participated in our survey, online searches for information on self-abortion may be driven by adolescents and young adults facing an unintended pregnancy. Implications Young women, in particular, may have an unmet need for information about safe and accessible abortion options. PMID:29477631

Metabonomics uncovers a reversible proatherogenic lipid profile during infliximab therapy of inflammatory bowel disease.

PubMed

Bjerrum, Jacob Tveiten; Steenholdt, Casper; Ainsworth, Mark; Nielsen, Ole Haagen; Reed, Michelle Ac; Atkins, Karen; Günther, Ulrich Leonhard; Hao, Fuhua; Wang, Yulan

2017-10-16

One-third of inflammatory bowel disease (IBD) patients show no response to infliximab (IFX) induction therapy, and approximately half of patients responding become unresponsive over time. Thus, identification of potential treatment response biomarkers are of great clinical significance. This study employs spectroscopy-based metabolic profiling of serum from patients with IBD treated with IFX and healthy subjects (1) to substantiate the use of spectroscopy as a semi-invasive diagnostic tool, (2) to identify potential biomarkers of treatment response and (3) to characterise the metabolic changes during management of patients with tumour necrosis factor-α inhibitors. Successive serum samples collected during IFX induction treatment (weeks 0, 2, 6 and 14) from 87 IBD patients and 37 controls were analysed by 1 H nuclear magnetic resonance (NMR) spectroscopy. Data were analysed with principal components analysis and orthogonal projection to latent structures discriminant analysis using SIMCA-P+ v12 and MATLAB. Metabolic profiles were significantly different between active ulcerative colitis and controls, active Crohn's disease and controls, and quiescent Crohn's disease and controls. Metabolites holding differential power belonged primarily to lipids and phospholipids with proatherogenic characteristics and metabolites in the pyruvate metabolism, suggestive of an intense inflammation-driven energy demand. IBD patients not responding to IFX were identified as a potentially distinct group based on their metabolic profile, although no applicable response biomarkers could be singled out in the current setting. 1 H NMR spectroscopy of serum samples is a powerful semi-invasive diagnostic tool in flaring IBD. With its use, we provide unique insights into the metabolic changes taking place during induction treatment with IFX. Of distinct clinical relevance is the identification of a reversible proatherogenic lipid profile in IBD patients with active disease, which partially explains the increased risk of cardiovascular disease associated with IBD.

HIV health center affiliation networks of black men who have sex with men: disentangling fragmented patterns of HIV prevention service utilization.

PubMed

Schneider, John A; Walsh, Tim; Cornwell, Benjamin; Ostrow, David; Michaels, Stuart; Laumann, Edward O

2012-08-01

In the United States, black men who have sex with men (BMSM) are at highest risk for HIV infection and are at high risk for limited health service utilization. We describe HIV health center (HHC) affiliation network patterns and their potential determinants among urban BMSM. The Men's Assessment of Social and Risk Network instrument was used to elicit HHC utilization, as reported by study respondents recruited through respondent-driven sampling. In 2010, 204 BMSM were systematically recruited from diverse venues in Chicago, IL. A 2-mode data set was constructed that included study participants and 9 diverse HHCs. Associations between individual-level characteristics and HHC utilization were analyzed using Multiple Regression Quadratic Assignment Procedure. Visualization analyses included computation of HHC centrality and faction membership. High utilization of HHCs (45.9%-70.3%) was evident among BMSM, 44.4% who were HIV infected. Multiple Regression Quadratic Assignment Procedure revealed that age, social network size, and HIV status were associated with HHC affiliation patterns (coeff., 0.13-0.27; all P < 0.05). With the exception of one HHC, HHCs offering HIV prevention services to HIV-infected participants occupied peripheral positions within the network of health centers. High-risk HIV-uninfected participants affiliated most with an HHC that offers only treatment services. Subcategories of BMSM in this sample affiliated with HHCs that may not provide appropriate HIV prevention services. Using 2-mode data, public health authorities may be better able to match prevention services to BMSM need; in particular, HIV prevention services for high-risk HIV-uninfected men and HIV "prevention for positives" services for HIV-infected men.

Temperature-Driven Structural and Morphological Evolution of Zinc Oxide Nano-Coalesced Microstructures and Its Defect-Related Photoluminescence Properties

PubMed Central

Lim, Karkeng; Abdul Hamid, Muhammad Azmi; Shamsudin, Roslinda; Al-Hardan, N.H.; Mansor, Ishak; Chiu, Weesiong

2016-01-01

In this paper, we address the synthesis of nano-coalesced microstructured zinc oxide thin films via a simple thermal evaporation process. The role of synthesis temperature on the structural, morphological, and optical properties of the prepared zinc oxide samples was deeply investigated. The obtained photoluminescence and X-ray photoelectron spectroscopy outcomes will be used to discuss the surface structure defects of the prepared samples. The results indicated that the prepared samples are polycrystalline in nature, and the sample prepared at 700 °C revealed a tremendously c-axis oriented zinc oxide. The temperature-driven morphological evolution of the zinc oxide nano-coalesced microstructures was perceived, resulting in transformation of quasi-mountain chain-like to pyramidal textured zinc oxide with increasing the synthesis temperature. The results also impart that the sample prepared at 500 °C shows a higher percentage of the zinc interstitial and oxygen vacancies. Furthermore, the intensity of the photoluminescence emission in the ultraviolet region was enhanced as the heating temperature increased from 500 °C to 700 °C. Lastly, the growth mechanism of the zinc oxide nano-coalesced microstructures is discussed according to the reaction conditions. PMID:28773425

Recruitment using mobile telephones in an Irish general population sexual health survey: challenges and practical solutions

PubMed Central

2012-01-01

Background Non-coverage of households without a landline telephone is a major concern of telephone survey researchers. Sampling mobile telephone users in national surveys is vital in order to gain access to the growing proportion of households that use mobile telephones extensively or exclusively. The complex logistics of conducting surveys with mobile telephones have been discussed in the literature. This paper outlines the actual challenges encountered during a recent national sexual health survey in Ireland, which utilized a mobile telephone sampling frame to recruit approximately half of the sample. Method The 2010 Irish Contraception and Crisis Pregnancy Survey (ICCP-2010) is a nationally representative sample of adults aged 18-45 years living in Ireland (n = 3002; 1416 recruited by landline telephone and 1586 recruited by mobile telephone). The overall response rate for the survey was 69% (79% for the landline telephone strand; 61% for the mobile telephone strand). All interviews were conducted using computer-assisting telephone interviewing. Results During the 18-week fieldwork period, five main challenges relating to the use of mobile telephones were encountered: (1) explaining to respondents how random digit dialling works in relation to mobile telephones; (2) establishing the respondent's eligibility; (3) calling the respondent with the Caller ID blocked or withheld; (4) calling the respondent when they are in any number of locations or situations; and (5) explaining to respondents the importance of refusal conversion calls for the response rate calculation. Details of how the survey protocols and procedures were monitored and adapted throughout the study to ensure a high response rate are outlined. Conclusion It is undeniably more challenging to recruit respondents using mobile telephones as opposed to landline telephones. Respondents are generally not familiar with being contacted on their personal mobile telephone for the purposes of being recruited for a research study. The main challenge for survey methodologists and interviewers is to devise simple protocols to explain to respondents why they are being contacted on a mobile telephone. Recommendations for survey researchers interested in using this methodological approach in the future are discussed. PMID:22475155

Depression and Social Stigma Among MSM in Lesotho: Implications for HIV and Sexually Transmitted Infection Prevention.

PubMed

Stahlman, Shauna; Grosso, Ashley; Ketende, Sosthenes; Sweitzer, Stephanie; Mothopeng, Tampose; Taruberekera, Noah; Nkonyana, John; Baral, Stefan

2015-08-01

Social stigma is common among men who have sex with men (MSM) across Sub-Saharan Africa, and may influence risks for HIV and sexually transmitted infections (STIs) via its association with depression. We conducted a cross-sectional study of 530 MSM in Lesotho accrued via respondent-driven sampling. Using generalized structural equation models we examined associations between stigma, social capital, and depression with condom use and testing positive for HIV/STIs. Depression was positively associated with social stigma experienced or perceived as a result of being MSM. In contrast, increasing levels of social cohesion were negatively associated with depression. Social stigma was associated with testing positive for HIV; however, this association did not appear to be mediated by depression or condom use. These data suggest a need for integrated HIV and mental health care that addresses stigma and discrimination and facilitates positive social support for MSM.

Depression and Social Stigma among MSM in Lesotho: Implications for HIV and Sexually Transmitted Infection Prevention

PubMed Central

Stahlman, Shauna; Grosso, Ashley; Ketende, Sosthenes; Sweitzer, Stephanie; Mothopeng, Tampose; Taruberekera, Noah; Nkonyana, John; Baral, Stefan

2016-01-01

Social stigma is common among men who have sex with men (MSM) across Sub-Saharan Africa, and may influence risks for HIV and sexually transmitted infections (STIs) via its association with depression. We conducted a cross-sectional study of 530 MSM in Lesotho accrued via respondent-driven sampling. Using generalized structural equation models we examined associations between stigma, social capital, and depression with condom use and testing positive for HIV/STIs. Depression was positively associated with social stigma experienced or perceived as a result of being MSM. In contrast, increasing levels of social cohesion were negatively associated with depression. Social stigma was associated with testing positive for HIV; however, this association did not appear to be mediated by depression or condom use. These data suggest a need for integrated HIV and mental health care that addresses stigma and discrimination and facilitates positive social support for MSM. PMID:25969182

Increasing Ethnic Minority Participation in Substance Abuse Clinical Trials: Lessons Learned in the National Institute on Drug Abuse’s Clinical Trials Network

PubMed Central

Burlew, Kathleen; Larios, Sandra; Suarez-Morales, Lourdes; Holmes, Beverly; Venner, Kamilla; Chavez, Roberta

2012-01-01

Underrepresentation in clinical trials limits the extent to which ethnic minorities benefit from advances in substance abuse treatment. The objective of this article is to share the knowledge gained within the Clinical Trials Network (CTN) of the National Institute on Drug Abuse and other research on recruiting and retaining ethnic minorities into substance abuse clinical trials. The article includes a discussion of two broad areas for improving inclusion— community involvement and cultural adaptation. CTN case studies are included to illustrate three promising strategies for improving ethnic minority inclusion: respondent-driven sampling, community-based participatory research, and the cultural adaptation of the recruitment and retention procedures. The article concludes with two sections describing a number of methodological concerns in the current research base and our proposed research agenda for improving ethnic minority inclusion that builds on the CTN experience. PMID:21988575

High Burden of HIV Infection and Risk Behaviors Among Female Sex Workers in Three Main Urban Areas of Mozambique.

PubMed

Augusto, Ângelo do Rosário; Young, Peter W; Horth, Roberta Z; Inguane, Celso; Sathane, Isabel; Ngale, Katia; Benedetti, Marcos; Cummings, Beverley; Botão, Carlos Francisco Sande; Baltazar, Cynthia Amino Semá; Frank, Heidi; Fagan, Jennifer; Fisher Raymond, Henry; McFarland, Willi

2016-04-01

This is the first integrated biological and behavioral survey among female sex workers (FSW) in Mozambique. Using respondent-driven sampling, 400, 411 and 429 FSW were enrolled respectively in Maputo, Beira and Nampula in 2011-2012. Estimates were produced using RDSAT 7.1. HIV prevalence was 31.2, 23.6, and 17.8 % in each location respectively. Among HIV-positive FSW, 48.1, 79.8 and 89.6 % in each city, were unaware of their serostatus. Condom use at last sex with a client was 85.8, 73.4 and 62.8 % among FSW, respectively. HIV was associated with current age, age of first sex for money, low educational level, and having had a genital ulcer in the last 6 months. Results suggest the urgent need to increase behavioral and structural interventions in this key population.

Increasing ethnic minority participation in substance abuse clinical trials: lessons learned in the National Institute on Drug Abuse's Clinical Trials Network.

PubMed

Burlew, Kathleen; Larios, Sandra; Suarez-Morales, Lourdes; Holmes, Beverly; Venner, Kamilla; Chavez, Roberta

2011-10-01

Underrepresentation in clinical trials limits the extent to which ethnic minorities benefit from advances in substance abuse treatment. The objective of this article is to share the knowledge gained within the Clinical Trials Network (CTN) of the National Institute on Drug Abuse and other research on recruiting and retaining ethnic minorities into substance abuse clinical trials. The article includes a discussion of two broad areas for improving inclusion-community involvement and cultural adaptation. CTN case studies are included to illustrate three promising strategies for improving ethnic minority inclusion: respondent-driven sampling, community-based participatory research, and the cultural adaptation of the recruitment and retention procedures. The article concludes with two sections describing a number of methodological concerns in the current research base and our proposed research agenda for improving ethnic minority inclusion that builds on the CTN experience.

Telling tails explain the discrepancy in sexual partner reports.

PubMed

Morris, M

1993-09-30

An anomaly often noted in surveys of sexual behaviour is that the number of female sexual partners reported by men exceeds the number of male partners reported by women. This discrepancy is sometimes interpreted as evidence that surveys produce unreliable data due to sex-linked response and sampling bias. We report here that among the 90% of respondents reporting fewer than 20 lifetime partners, however, the ratio of male to female reports drops from 3.2:1 to 1.2:1. The anomaly thus appears to be driven by the upper tail of the contact distribution, an example of the general principle of outlier influence in data analysis. The implication is that sexual behaviour surveys provide reliable data in the main, and that simple improvements can increase precision in the upper tail to make these data more useful for modelling the spread of AIDS and other sexually transmitted diseases.

Chicago Residents’ Perceptions of Air Quality: Objective Pollution, the Built Environment, and Neighborhood Stigma Theory

PubMed Central

King, Katherine E.

2014-01-01

Substantial research documents higher pollution levels in minority neighborhoods, but little research evaluates how residents perceive their own communities’ pollution risks. According to “Neighborhood stigma” theory, survey respondents share a cultural bias that minorities cause social dysfunction, leading to over-reports of dysfunction in minority communities. This study investigates perceptions of residential outdoor air quality by linking objective data on built and social environments with multiple measures of pollution and a representative survey of Chicago residents. Consistent with the scholarly narrative, results show air quality is rated worse where minorities and poverty are concentrated, even after extensive adjustment for objective pollution and built environment measures. Perceptions of air pollution may thus be driven by neighborhood socioeconomic position far more than by respondents’ ability to perceive pollution. The finding that 63.5% of the sample reported excellent or good air quality helps to explain current challenging in promoting environmental action. PMID:26527847

HIV infection and mental health of "money boys": a pilot study in Shandong Province, China.

PubMed

Tao, Xiaorun; Gai, Ruoyan; Zhang, Na; Zheng, Wei; Zhang, Xiaofei; Xu, Aiqiang; Li, Shixue

2010-03-01

A pilot study was conducted in eight cities of Shandong Province, China to examine the seroprevalence of HIV and syphilis infection, and the mental health of "money boys" who were recruited by respondent-driven sampling and interviewed using a semi-structured questionnaire. The prevalence of the HIV-positive among money boys was 5.1%. Factors associated with the infection were having sex with women in the past 6 months (p < 0.05) and suffering STD-like symptoms (p < 0.01). The prevalence of syphilis was 10.2%. There were 77.2% participants engaged in such an occupation for economic survival. The prevalence of anxiety and depression among money boys was 46.6% and 68.1%, respectively. Heterosexual money boys were more likely to suffer from such mental symptoms. This study revealed the urgent need for interventions for HIV/AIDS control, together with mental counseling, targeting this vulnerable population.

HMM-based lexicon-driven and lexicon-free word recognition for online handwritten Indic scripts.

PubMed

Bharath, A; Madhvanath, Sriganesh

2012-04-01

Research for recognizing online handwritten words in Indic scripts is at its early stages when compared to Latin and Oriental scripts. In this paper, we address this problem specifically for two major Indic scripts--Devanagari and Tamil. In contrast to previous approaches, the techniques we propose are largely data driven and script independent. We propose two different techniques for word recognition based on Hidden Markov Models (HMM): lexicon driven and lexicon free. The lexicon-driven technique models each word in the lexicon as a sequence of symbol HMMs according to a standard symbol writing order derived from the phonetic representation. The lexicon-free technique uses a novel Bag-of-Symbols representation of the handwritten word that is independent of symbol order and allows rapid pruning of the lexicon. On handwritten Devanagari word samples featuring both standard and nonstandard symbol writing orders, a combination of lexicon-driven and lexicon-free recognizers significantly outperforms either of them used in isolation. In contrast, most Tamil word samples feature the standard symbol order, and the lexicon-driven recognizer outperforms the lexicon free one as well as their combination. The best recognition accuracies obtained for 20,000 word lexicons are 87.13 percent for Devanagari when the two recognizers are combined, and 91.8 percent for Tamil using the lexicon-driven technique.

Differential clonal evolution in oesophageal cancers in response to neo-adjuvant chemotherapy.

PubMed

Findlay, John M; Castro-Giner, Francesc; Makino, Seiko; Rayner, Emily; Kartsonaki, Christiana; Cross, William; Kovac, Michal; Ulahannan, Danny; Palles, Claire; Gillies, Richard S; MacGregor, Thomas P; Church, David; Maynard, Nicholas D; Buffa, Francesca; Cazier, Jean-Baptiste; Graham, Trevor A; Wang, Lai-Mun; Sharma, Ricky A; Middleton, Mark; Tomlinson, Ian

2016-04-05

How chemotherapy affects carcinoma genomes is largely unknown. Here we report whole-exome and deep sequencing of 30 paired oesophageal adenocarcinomas sampled before and after neo-adjuvant chemotherapy. Most, but not all, good responders pass through genetic bottlenecks, a feature associated with higher mutation burden pre-treatment. Some poor responders pass through bottlenecks, but re-grow by the time of surgical resection, suggesting a missed therapeutic opportunity. Cancers often show major changes in driver mutation presence or frequency after treatment, owing to outgrowth persistence or loss of sub-clones, copy number changes, polyclonality and/or spatial genetic heterogeneity. Post-therapy mutation spectrum shifts are also common, particularly C>A and TT>CT changes in good responders or bottleneckers. Post-treatment samples may also acquire mutations in known cancer driver genes (for example, SF3B1, TAF1 and CCND2) that are absent from the paired pre-treatment sample. Neo-adjuvant chemotherapy can rapidly and profoundly affect the oesophageal adenocarcinoma genome. Monitoring molecular changes during treatment may be clinically useful.

The impact of sharing arrangement institution on beef cattle breeding performance in Kupang District, East Nusa Tenggara Province, Indonesia

NASA Astrophysics Data System (ADS)

Nono, O. H.; Natawidjaja, R.; Arief, B.; Suryadi, D.; Kapa, M. M. J.

2018-02-01

The aim of this study was to analyse the impact of sharing arrangement systems to performance of beef cattle breeding. This research was conducted in Kupang Regency - East Nusa Tenggara Province, Indonesia. The study used multi stage cluster random sampling method to determine the sample area and respondents. The sample areas consisted of 2 sub-districts and 6 villages, while the total respondents were 117 people comprised 74 Participant Farmers (PF) of sharing arrangement systems (SAS) and 43 non-participant farmers (NPF). 23 investors were selected for the survey. The result of the study indicated that the performance of NPF in terms of revenue, net profit, and return on investment (ROI) was better than PF respondents. The value of ROI was between 16.69-32.23 %. This indicated that utilization of farm asset was not optimum yet. It was found that farm efficiency was 1.73 which indicated that SAS does not increase farm productivity.

Types of Bullying in the Senior High Schools in Ghana

ERIC Educational Resources Information Center

Antiri, Kwasi Otopa

2016-01-01

The main objective of the study was to examine the types of bullying that were taking place in the senior high schools in Ghana. A multi-stage sampling procedure, comprising purposive, simple random and snowball sampling technique, was used in the selection of the sample. A total of 354 respondents were drawn six schools in Ashanti, Central and…

Injection molding of iPP samples in controlled conditions and resulting morphology

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

Sessa, Nino, E-mail: ninosessa.ns@gmail.com; De Santis, Felice, E-mail: fedesantis@unisa.it; Pantani, Roberto, E-mail: rpantani@unisa.it

2015-12-17

Injection molded parts are driven down in size and weight especially for electronic applications. In this work, an investigation was carried out on the process of injection molding of thin iPP samples and on the morphology of these parts. Melt flow in the mold cavity was analyzed and described with a mathematical model. Influence of mold temperature and injection pressure was analyzed. Samples orientation was studied using optical microscopy.

Intimate Partner Violence Reported by Two Samples of Deaf Adults via a Computerized American Sign Language Survey

PubMed Central

Pollard, Robert Q; Sutter, Erika; Cerulli, Catherine

2014-01-01

A computerized sign language survey was administered to two large samples of deaf adults. Six questions regarding intimate partner violence (IPV) were included, querying lifetime and past-year experiences of emotional abuse, physical abuse, and forced sex. Comparison data were available from a telephone survey of local households. Deaf respondents reported high rates of emotional abuse and much higher rates of forced sex than general population respondents. Physical abuse rates were comparable between groups. More men than women in both deaf samples reported past-year physical and sexual abuse. Past-year IPV was associated with higher utilization of hospital emergency services. Implications for IPV research, education, and intervention in the Deaf community are discussed. PMID:24142445

Suicidal Behavior Among Female Sex Workers in Goa, India: The Silent Epidemic

PubMed Central

Wayal, Sonali; Cowan, Frances; Mabey, David; Copas, Andrew; Patel, Vikram

2009-01-01

Objectives. We sought to study suicidal behavior prevalence and its association with social and gender disadvantage, sex work, and health factors among female sex workers in Goa, India. Methods. Using respondent-driven sampling, we recruited 326 sex workers in Goa for an interviewer-administered questionnaire regarding self-harming behaviors, sociodemographics, sex work, gender disadvantage, and health. Participants were tested for sexually transmitted infections. We used multivariate analysis to define suicide attempt determinants. Results. Nineteen percent of sex workers in the sample reported attempted suicide in the past 3 months. Attempts were independently associated with intimate partner violence (adjusted odds ratio [AOR] = 2.70; 95% confidence interval [CI] = 1.38, 5.28), violence from others (AOR = 2.26; 95% CI = 1.15, 4.45), entrapment (AOR = 2.76; 95% CI = 1.11, 6.83), regular customers (AOR = 3.20; 95% CI = 1.61, 6.35), and worsening mental health (AOR = 1.05; 95% CI = 1.01, 1.11). Lower suicide attempt likelihood was associated with Kannad ethnicity, HIV prevention services, and having a child. Conclusions. Suicidal behaviors among sex workers were common and associated with gender disadvantage and poor mental health. India's widespread HIV-prevention programs for sex workers provide an opportunity for community-based interventions against gender-based violence and for mental health services delivery. PMID:19443819

Perceived Risk of Methamphetamine among Chinese Methamphetamine Users

PubMed Central

Kelly, Brian C; Liu, Tieqiao; Yang, Xiaozhao Yosef; Zhang, Guanbai; Hao, Wei; Wang, Jichuan

2014-01-01

Background Methamphetamine use has grown considerably in China in recent years. Information about perceptions of risk on methamphetamine is important to facilitate health promotion efforts. Methods Using both survey data and qualitative interview data, the authors evaluate the perceived risk of methamphetamine use among Chinese users using a mixed-methods approach. Through Respondent Driven Sampling, the authors recruited a sample of 303 methamphetamine users in Changsha, China. Results A majority (59.1%) perceive that infrequent methamphetamine use poses no risk to the user, while 11.2% perceive at least moderate risk for light use. A majority (56.7%) perceived at least moderate risk associated with regular methamphetamine use. Most (82.2%) also perceive methamphetamine to be easily obtainable. A path model indicates that perceived risk shapes intentions to use and expectations of future use, as does perceived availability. Qualitatively, while addiction was the most common risk discussed by users, they differed on whether they perceived the drug addictive. Other concerns raised by interviewees included impaired cognition, mental health problems, physical harm, and social dysfunction. Discussion While some users identify significant risks with methamphetamine, others do not perceive its use to be problematic. Collectively, these findings indicate that intervening upon perceptions of risk among Chinese methamphetamine users may be a means to influence intentions to use. PMID:24925820

Reasons for tanning bed use: a survey of community college students in North Carolina.

PubMed

Neenan, Ashley; Lea, C Suzanne; Lesesky, Erin B

2012-01-01

Tanning bed use is classified as carcinogenic and is associated with an increased risk of skin cancer. The aim of this cross-sectional survey was to identify the most commonly stated reasons for tanning bed use among a sample of male and female community college students in eastern North Carolina. A brief, self-administered survey was distributed to students during English, Art, or Psychology class periods in 5 eastern North Carolina community colleges during the 2010 fall semester. The 95% response rate consisted of 487 returned surveys. Of the 487 respondents, 12.7% (N = 62) were current users, 24.5% (N = 119) were past users, and 62.2% (N = 303) reported never using tanning beds. Women (79%) were more likely than men (18%) to be current or former tanning bed users. Three African Americans reported current tanning bed use (4.8%). Reasons for tanning bed use were similar among men and women, with "I think I look better when I am tan" being the most commonly cited reason (70.2%) for tanning bed use. A convenience sample limits generalizability to all North Carolina students attending community college. Current tanning bed use was not widely reported. However, educational strategies for preventing tanning bed initiation or recurrence among male and female community college students should include appearance-driven factors.

Police-Related Experiences and HIV Risk Among Female Sex Workers in Andhra Pradesh, India

PubMed Central

Reed, Elizabeth; Blankenship, Kim M.

2011-01-01

Research suggests experiences with police are related to human immunodeficiency virus (HIV) sexual risk among women working as sex workers. However, little is known about the links between specific police-related behaviors and HIV vulnerability. We examine whether 5 police-related experiences are associated with measures of HIV risk and violence among a sample of female sex workers (FSWs) in Andhra Pradesh, India, and consider the implications for HIV prevention. FSWs at least 18 years of age (n = 835) were recruited through respondent-driven sampling for a cross-sectional survey conducted as part of Avahan, the India AIDS Initiative. Using logistic regression models adjusted for age, age at start of sex work, and sex work venue, we assessed police-related experiences reported by FSWs in relation to HIV risk behaviors and violence. Results showed having sex with police to avoid trouble, giving gifts to police to avoid trouble, having police take condoms away, experiencing a workplace raid, and being arrested were associated with sexually transmitted infection symptoms, inconsistent condom use, acceptance of more money for sex without a condom, and experience of client violence. These findings suggest a need for interventions targeting police–FSW interactions to reduce HIV vulnerability among FSWs. PMID:22043036

Label-free LC-MSMS analysis of vitreous from autoimmune uveitis reveals a significant decrease in secreted Wnt signalling inhibitors DKK3 and SFRP2.

PubMed

Hauck, Stefanie M; Hofmaier, Florian; Dietter, Johannes; Swadzba, Margarete E; Blindert, Marcel; Amann, Barbara; Behler, Jennifer; Kremmer, Elisabeth; Ueffing, Marius; Deeg, Cornelia A

2012-07-19

Equine recurrent uveitis is a severe and frequent blinding disease in horses which presents with auto-reactive invading T-cells, resulting in the destruction of the inner eye. Infiltration of inflammatory cells into the retina and vitreous is driven by currently unknown guidance cues, however surgical removal of the vitreous (vitrectomy) has proven therapeutically successful. Therefore, proteomic analyses of vitrectomy samples are likely to result in detection of proteins contributing to disease pathogenesis. Vitreous from healthy and ERU diseased horses were directly compared by quantitative mass spectrometry based on label-free quantification of peak intensities across samples. We found a significant upregulation of complement and coagulation cascades and downregulation of negative paracrine regulators of canonical Wnt signalling including the Wnt signalling inhibitors DKK3 and SFRP2. Based on immunohistochemistry, both proteins are expressed in equine retina and suggest localisation to retinal Müller glial cells (RMG), which may be the source cells for these proteins. Furthermore, retinal expression levels and patterns of DKK3 change in response to ERU. Since many other regulated proteins identified here are associated with RMG cells, these cells qualify as the prime responders to autoimmune triggers. Copyright © 2012 Elsevier B.V. All rights reserved.

Factors associated with self-reported discrimination against men who have sex with men in Brazil

PubMed Central

Magno, Laio; Dourado, Inês; da Silva, Luís Augusto V; Brignol, Sandra; de Brito, Ana Maria; Guimarães, Mark Drew Crosland; Benzaken, Adele; Pinho, Adriana de A; Kendall, Carl; Kerr, Ligia Regina Franco Sansigolo

2017-01-01

ABSTRACT OBJECTIVE To estimate self-reported discrimination due to sexual orientation among men who have sex with men (MSM) in Brazil and to analyze associated factors. METHODS A cross-sectional study of 3,859 MSM recruited in 2008–2009 with respondent driven sampling. Data collection conducted in health centers in 10 Brazilian cities. A face-to-face questionnaire was used and rapid HIV and syphilis tests conducted. Aggregated data were weighted and adjusted odds ratio estimated to measure the association between selected factors and self-reported discrimination due to sexual orientation. RESULTS The sample was predominantly young, eight plus years of schooling, pardo (brown), single, low-income, and identified themselves as gay or homosexual. The prevalence of self-reported discrimination due to sexual orientation was 27.7% (95%CI 26.2–29.1). Discrimination was independently associated with: age < 30 years, more years of schooling, community involvement and support, history of sexual and physical violence, suicidal thoughts, and unprotected receptive anal intercourse. CONCLUSIONS The prevalence of self-reported discrimination among MSM in Brazil is high. These results challenge the assumptions that MSM-specific prevention and support programs are not required or that health professionals do not need special training to address MSM needs. PMID:29166436

Including Online-Recruited Seeds: A Respondent-Driven Sample of Men Who Have Sex With Men.

PubMed

Lachowsky, Nathan John; Lal, Allan; Forrest, Jamie I; Card, Kiffer George; Cui, Zishan; Sereda, Paul; Rich, Ashleigh; Raymond, Henry Fisher; Roth, Eric A; Moore, David M; Hogg, Robert S

2016-03-15

Technology has changed the way men who have sex with men (MSM) seek sex and socialize, which may impact the implementation of respondent-driven sampling (RDS) among this population. Initial participants (also known as seeds) are a critical consideration in RDS because they begin the recruitment chains. However, little information is available on how the online-recruited seeds may effect RDS implementation. The objectives of this study were to compare (1) online-recruited versus offline-recruited seeds and (2) subsequent recruitment chains of online-recruited versus offline-recruited seeds. Between 2012 and 2014, we recruited MSM using RDS in Vancouver, Canada. RDS weights were used with logistic regression to address each objective. A total of 119 seeds were used, 85 of whom were online-recruited seeds, to recruit an additional 600 MSM. Compared with offline-recruited seeds, online-recruited seeds were less likely to be HIV-positive (OR 0.34, 95% CI 0.13-0.88), to have attended a gay community group (AOR 0.33, 95% CI 0.12-0.90), and to feel gay community involvement was "very important" (AOR 0.16, 95% CI 0.03-0.93). Online-recruited seeds were more likely to ask a sexual partner's HIV status always versus <50% of the time (AOR 5.21, 95% CI 1.17-23.23), to have watched the Pride parade (AOR 6.30, 95% CI 1.69-23.45), and to have sought sex online (AOR 4.29, 95% CI 1.53-12-12.05). Further, compared with recruitment chains started by offline-recruited seeds, recruits from chains started by online-recruited seeds (283/600, 47.2%) were less likely to be HIV-positive (AOR 0.25, 95% CI 0.16-0.40), to report "versatile" versus "bottom" sexual position preference (AOR 0.56, 95% CI 0.35-0.88), and to be in a relationship lasting >1 year (AOR 1.65, 95% CI 1.06-2.56). Recruits of online seeds were more likely to be out as gay for longer (eg, 11-21 vs 1-4 years, AOR 2.22, 95% CI 1.27-3.88) and have fewer Facebook friends (eg, 201-500 vs >500, AOR 1.69, 95% CI 1.02-2.80). Online-recruited seeds were more prevalent, recruited fewer participants, but were different from those recruited offline. This may therefore help create a more diverse overall sample. Our work has shown the value of geosocial networking apps for aiding RDS recruitment efforts, especially when faced with slow participation uptake by other means. Understanding the degree to which networks interact will be an important next step in confirming the efficacy of online RDS recruitment strategies.

Including Online-Recruited Seeds: A Respondent-Driven Sample of Men Who Have Sex With Men

PubMed Central

Lachowsky, Nathan John; Lal, Allan; Forrest, Jamie I; Card, Kiffer George; Cui, Zishan; Sereda, Paul; Rich, Ashleigh; Raymond, Henry Fisher; Roth, Eric A; Moore, David M

2016-01-01

Background Technology has changed the way men who have sex with men (MSM) seek sex and socialize, which may impact the implementation of respondent-driven sampling (RDS) among this population. Initial participants (also known as seeds) are a critical consideration in RDS because they begin the recruitment chains. However, little information is available on how the online-recruited seeds may effect RDS implementation. Objective The objectives of this study were to compare (1) online-recruited versus offline-recruited seeds and (2) subsequent recruitment chains of online-recruited versus offline-recruited seeds. Methods Between 2012 and 2014, we recruited MSM using RDS in Vancouver, Canada. RDS weights were used with logistic regression to address each objective. Results A total of 119 seeds were used, 85 of whom were online-recruited seeds, to recruit an additional 600 MSM. Compared with offline-recruited seeds, online-recruited seeds were less likely to be HIV-positive (OR 0.34, 95% CI 0.13-0.88), to have attended a gay community group (AOR 0.33, 95% CI 0.12-0.90), and to feel gay community involvement was “very important” (AOR 0.16, 95% CI 0.03-0.93). Online-recruited seeds were more likely to ask a sexual partner’s HIV status always versus <50% of the time (AOR 5.21, 95% CI 1.17-23.23), to have watched the Pride parade (AOR 6.30, 95% CI 1.69-23.45), and to have sought sex online (AOR 4.29, 95% CI 1.53-12-12.05). Further, compared with recruitment chains started by offline-recruited seeds, recruits from chains started by online-recruited seeds (283/600, 47.2%) were less likely to be HIV-positive (AOR 0.25, 95% CI 0.16-0.40), to report “versatile” versus “bottom” sexual position preference (AOR 0.56, 95% CI 0.35-0.88), and to be in a relationship lasting >1 year (AOR 1.65, 95% CI 1.06-2.56). Recruits of online seeds were more likely to be out as gay for longer (eg, 11-21 vs 1-4 years, AOR 2.22, 95% CI 1.27-3.88) and have fewer Facebook friends (eg, 201-500 vs >500, AOR 1.69, 95% CI 1.02-2.80). Conclusions Online-recruited seeds were more prevalent, recruited fewer participants, but were different from those recruited offline. This may therefore help create a more diverse overall sample. Our work has shown the value of geosocial networking apps for aiding RDS recruitment efforts, especially when faced with slow participation uptake by other means. Understanding the degree to which networks interact will be an important next step in confirming the efficacy of online RDS recruitment strategies. PMID:26980147

Examination of the Triarchic Assessment Procedure for Inconsistent Responding in six non-English language samples.

PubMed

Kelley, Shannon E; van Dongen, Josanne D M; Donnellan, M Brent; Edens, John F; Eisenbarth, Hedwig; Fossati, Andrea; Howner, Katarina; Somma, Antonella; Sörman, Karolina

2018-05-01

The Triarchic Assessment Procedure for Inconsistent Responding (TAPIR; Mowle et al., 2016) was recently developed to identify inattentiveness or comprehension difficulties that may compromise the validity of responses on the Triarchic Psychopathy Measure (TriPM; Patrick, 2010). The TAPIR initially was constructed and cross-validated using exclusively English-speaking participants from the United States; however, research using the TriPM has been increasingly conducted internationally, with numerous foreign language translations of the measure emerging. The present study examined the cross-language utility of the TAPIR in German, Dutch, Swedish, and Italian translations of the TriPM using 6 archival samples of community members, university students, forensic psychiatric inpatients, forensic detainees, and adolescents residing outside the United States (combined N = 5,404). Findings suggest that the TAPIR effectively detects careless responding across these 4 translated versions of the TriPM without the need for language-specific modifications. The TAPIR total score meaningfully discriminated genuine participant responses from both fully and partially randomly generated data in every sample, and demonstrated further utility in detecting fixed "all true" or "all false" response patterns. In addition, TAPIR scores were reliably associated with inconsistent responding scores from another psychopathy inventory. Specificity for a range of tentative cut scores for assessing profile validity was modestly reduced among our samples relative to rates previously obtained with the English version of the TriPM; however, overall the TAPIR appears to demonstrate satisfactory cross-language generalizability. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The relationship between processing style, trauma memory processes, and the development of posttraumatic stress symptoms in children and adolescents.

PubMed

McKinnon, Anna; Brewer, Neil; Cameron, Kate; Nixon, Reginald D V

2017-12-01

Data-driven processing, peri-event fear, and trauma memory characteristics are hypothesised to play a core role in the development of Posttraumatic Stress Disorder. We assessed the relationships between these characteristics and Posttraumatic Stress (PTS) symptoms in a sample of youth. Study 1 (N = 36, 7-16 years), involved a sample of children who had undergone a stressful orthopaedic procedure. One week later they answered a series of probed recall questions about the trauma (assessed for accuracy by comparison to a video) and reported on their PTS symptoms. They also rated confidence in their probed recall answers to assess meta-cognitive monitoring of their memory for the trauma. In Study 2, a sample of injured children (N = 57, 7-16 years) were assessed within 1-month of a visit to an Emergency Department, and then at 3-month follow-up. They answered probed recall questions, made confidence ratings, and completed measures of data-driven processing, peri-event fear, PTS and associated psychopathology. Memories were verified using witness accounts. Studies 1 and 2 did not find an association between PTS symptoms and trauma memory accuracy or confidence. In Studies 1 and 2 data-driven processing predicted PTS symptoms. The studies had modest samples sizes and there were ceiling effects for some accuracy and confidence items. Data-driven processing at the time of a trauma was associated with PTS symptoms after accounting for fear at the time of the trauma. Accuracy of recall for trauma memories was not significantly related to PTS symptoms. No decisive conclusion could be drawn regarding the relation between confidence in trauma memories and PTS symptoms. Copyright © 2017 Elsevier Ltd. All rights reserved.

Induction of IL-21 in Peripheral T Follicular Helper cells is Indicator of Influenza Vaccine Response in Previously Vaccinated HIV-Infected Pediatric Cohort

PubMed Central

de Armas, Lesley R.; Cotugno, Nicola; Pallikkuth, Suresh; Pan, Li; Rinaldi, Stefano; Sanchez, M. Celeste; Gonzalez, Louis; Cagigi, Alberto; Rossi, Paolo; Palma, Paolo; Pahwa, Savita

2016-01-01

HIV-infected patients of all ages frequently underperform in responsiveness to seasonal influenza vaccination despite virologic control of HIV. Molecular mechanisms governing this impairment as well as predictive biomarkers for responsiveness remain unknown. This study was performed in pre-vaccination samples (T0) of HIV-infected children who received the 2012–2013 seasonal influenza vaccine. Response status was determined based on established criteria of hemagglutination inhibition (HAI) titer; participants with HAI ≥ 1:40 plus ≥ 4-fold increase over T0 at three weeks post-vaccination (T1) were designated as responders. All children had a history of prior influenza vaccinations. At T0, frequencies of CD4 T cell subsets, including peripheral T follicular helper (pTfh) cells which provide help to B cells for developing into Ab secreting cells were similar between responders and non-responders. However, in response to in vitro stimulation with H1N1 antigen, differential gene expression related to pTfh function was observed by Fluidigm high density RT-PCR between responders and non-responders. In responders, H1N1 stimulation at pre-vaccination also resulted in CXCR5 induction (mRNA and protein) in CD4 T cells and IL21 gene induction in pTfh cells that strongly associated with H1N1-specific B cell responses post-vaccination. In contrast, CD4 T cells of non-responders exhibited increased expression of IL2 and STAT5 genes which are known to antagonize pTfh function. These results suggest that the quality of pTfh at the time of immunization are important for influenza vaccine responses and provide a rationale for targeted, ex vivo antigen-driven molecular profiling of purified immune cells to detect predictive biomarkers of vaccine response. PMID:28130496

Nanopipettes: probes for local sample analysis.

PubMed

Saha-Shah, Anumita; Weber, Anna E; Karty, Jonathan A; Ray, Steven J; Hieftje, Gary M; Baker, Lane A

2015-06-01

Nanopipettes (pipettes with diameters <1 μm) were explored as pressure-driven fluid manipulation tools for sampling nanoliter volumes of fluids. The fundamental behavior of fluids confined in the narrow channels of the nanopipette shank was studied to optimize sampling volume and probe geometry. This method was utilized to collect nanoliter volumes (<10 nL) of sample from single Allium cepa cells and live Drosophila melanogaster first instar larvae. Matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was utilized to characterize the collected sample. The use of nanopipettes for surface sampling of mouse brain tissue sections was also explored. Lipid analyses were performed on mouse brain tissues with spatial resolution of sampling as small as 50 μm. Nanopipettes were shown to be a versatile tool that will find further application in studies of sample heterogeneity and population analysis for a wide range of samples.

Statistical Inference for Data Adaptive Target Parameters.

PubMed

Hubbard, Alan E; Kherad-Pajouh, Sara; van der Laan, Mark J

2016-05-01

Consider one observes n i.i.d. copies of a random variable with a probability distribution that is known to be an element of a particular statistical model. In order to define our statistical target we partition the sample in V equal size sub-samples, and use this partitioning to define V splits in an estimation sample (one of the V subsamples) and corresponding complementary parameter-generating sample. For each of the V parameter-generating samples, we apply an algorithm that maps the sample to a statistical target parameter. We define our sample-split data adaptive statistical target parameter as the average of these V-sample specific target parameters. We present an estimator (and corresponding central limit theorem) of this type of data adaptive target parameter. This general methodology for generating data adaptive target parameters is demonstrated with a number of practical examples that highlight new opportunities for statistical learning from data. This new framework provides a rigorous statistical methodology for both exploratory and confirmatory analysis within the same data. Given that more research is becoming "data-driven", the theory developed within this paper provides a new impetus for a greater involvement of statistical inference into problems that are being increasingly addressed by clever, yet ad hoc pattern finding methods. To suggest such potential, and to verify the predictions of the theory, extensive simulation studies, along with a data analysis based on adaptively determined intervention rules are shown and give insight into how to structure such an approach. The results show that the data adaptive target parameter approach provides a general framework and resulting methodology for data-driven science.

Sampling in epidemiological research: issues, hazards and pitfalls.

PubMed

Tyrer, Stephen; Heyman, Bob

2016-04-01

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.

Sampling in epidemiological research: issues, hazards and pitfalls

PubMed Central

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

The impact of sampling, PCR, and sequencing replication on discerning changes in drinking water bacterial community over diurnal time-scales.

PubMed

Bautista-de Los Santos, Quyen Melina; Schroeder, Joanna L; Blakemore, Oliver; Moses, Jonathan; Haffey, Mark; Sloan, William; Pinto, Ameet J

2016-03-01

High-throughput and deep DNA sequencing, particularly amplicon sequencing, is being increasingly utilized to reveal spatial and temporal dynamics of bacterial communities in drinking water systems. Whilst the sampling and methodological biases associated with PCR and sequencing have been studied in other environments, they have not been quantified for drinking water. These biases are likely to have the greatest effect on the ability to characterize subtle spatio-temporal patterns influenced by process/environmental conditions. In such cases, intra-sample variability may swamp any underlying small, systematic variation. To evaluate this, we undertook a study with replication at multiple levels including sampling sites, sample collection, PCR amplification, and high throughput sequencing of 16S rRNA amplicons. The variability inherent to the PCR amplification and sequencing steps is significant enough to mask differences between bacterial communities from replicate samples. This was largely driven by greater variability in detection of rare bacteria (relative abundance <0.01%) across PCR/sequencing replicates as compared to replicate samples. Despite this, we captured significant changes in bacterial community over diurnal time-scales and find that the extent and pattern of diurnal changes is specific to each sampling location. Further, we find diurnal changes in bacterial community arise due to differences in the presence/absence of the low abundance bacteria and changes in the relative abundance of dominant bacteria. Finally, we show that bacterial community composition is significantly different across sampling sites for time-periods during which there are typically rapid changes in water use. This suggests hydraulic changes (driven by changes in water demand) contribute to shaping the bacterial community in bulk drinking water over diurnal time-scales. Copyright © 2015 Elsevier Ltd. All rights reserved.

Design of a sample acquistion system for the Mars exobiological penetrator

NASA Technical Reports Server (NTRS)

Thomson, Ron; Gwynne, Owen

1988-01-01

The Mars Exobiological Penetrator will be imbedded into several locations on the Martian surface. It contains various scientific instruments, such as an Alpha-Particle Instrument (API), Differential Scanning Calorimeter (DSC), Evolved Gas Analyzer (EGA) and accelerometers. A sample is required for analysis in the API and DSC. To avoid impact contaminated material, this sample must be taken from soil greater than 2 cm away from the penetrator shell. This study examines the design of a dedicated sampling system including deployment, suspension, fore/after body coupling, sample gathering and placement. To prevent subsurface material from entering the penetrator sampling compartment during impact, a plug is placed in the exit hole of the wall. A U-lever device is used to hold this plug in the penetrator wall. The U-lever rotates upon initial motion of the core-grinder mechanism (CGM), releasing the plug. Research points to a combination of coring and grinding as a plausible solution to the problem of dry drilling. The CGM, driven by two compressed springs, will be deployed along a tracking system. A slowly varying load i.e., springs, is favored over a fixed displacement motion because of its adaptability to different material hardness. However, to accommodate sampling in a low density soil, two dash pots set a maximum transverse velocity. In addition, minimal power use is achieved by unidirectional motion of the CGM. The sample will be transported to the scientific instruments by means of a sample placement tray that is driven by a compressed spring to avoid unnecessary power usage. This paper also explores possible modifications for size, weight, and time as well as possible future studies.

National survey of Ebola-related knowledge, attitudes and practices before the outbreak peak in Sierra Leone: August 2014

PubMed Central

Jalloh, Mohamed F; Sengeh, Paul; Monasch, Roeland; Jalloh, Mohammad B; DeLuca, Nickolas; Dyson, Meredith; Golfa, Sheku; Sakurai, Yukiko; Conteh, Lansana; Sesay, Samuel; Brown, Vance; Li, Wenshu; Mermin, Jonathan; Bunnell, Rebecca

2017-01-01

Background The 2014–2015 Ebola epidemic in West Africa was the largest ever to occur. In the early phases, little was known about public knowledge, attitudes and practices (KAP) relating to Ebola virus disease (Ebola). Data were needed to develop evidence-driven strategies to address gaps in knowledge and practice. Methods In August 2014, we conducted interviews with 1413 randomly selected respondents from 9 out of 14 districts in Sierra Leone using multistage cluster sampling. Where suitable, Ebola-related KAP questions were adapted from other internationally validated questionnaires related to infectious diseases. Results All respondents were aware of Ebola. When asked unprompted, 60% of respondents could correctly cite fever, diarrhoea and vomiting as signs/symptoms of Ebola. A majority of respondents knew that avoiding infected blood and bodily fluids (87%) and contact with an infected corpse (85%) could prevent Ebola. However, there were also widespread misconceptions such as the belief that Ebola can be prevented by washing with salt and hot water (41%). Almost everyone interviewed (95%) expressed at least one discriminatory attitude towards Ebola survivors. Unprompted, self-reported actions taken to avoid Ebola infection included handwashing with soap (66%) and avoiding physical contact with patients with suspected Ebola (40%). Conclusion Three months into the 2014 Ebola outbreak in Sierra Leone, our findings suggest there was high awareness of the disease but misconceptions and discriminatory attitudes toward survivors remained common. These findings directly informed the development of a national social mobilisation strategy and demonstrated the importance of KAP assessment early in an epidemic. PMID:29259820

[Serological and epidemiological confirmation of leptospirosis epidemic in the mine "Stara Jama" in Zenica in 2005].

PubMed

Tandir, Salih; Drljević, Ednan; Calkić, Lejla

2006-01-01

Leptospirosys belong to zoonoses that affects both humans and animals, and they are caused by the bacterias of leptospira sort. This is a relatively widely spread illness in the majority of countries around the world as well as in our country, whit often epidemic occurrence. The goal of the paper is to point out the importance of leptospira as a potential cause for individual or epidemic sickening of miners at the "Stara Jama" mine in Zenica. This research is conducted on a sample of 31 respondents--miners at the "Stara Jama" mine in Zenica during the epidemic of leptospirosys from 1st august until 6th September 2005. Selection of suspected patients is done based on a clinical signs of illness. All hospitalized had high fever, headache and hepatorenal syndrome. All complete and relevant tests are done for the 30 respondents, and from 26 of them one or two serum samples are taken, while from 4 patient's three samples are taken. Serological examination is conducted by the standard method of microscopic agglutination - liza-test with 14 serotypes of leptospira, From the baseline of 30 respondents in 16 cases existed serological confirmation of leptospirosys etiology of illness. Among them also is determined a presence of specific antibodies in I, II and/or III serum sample for the certain serotypes of leptospira. Among other 14 hospitalized, from the sample of 30 respondents we did not find increase in titre for the specific antibodies within samples. Illness developed mainly among those in the age group between 24 and 56 years, and the highest frequency was between 20 and 50 years of age among male respondents. Antibody titre within the taken samples was in a solution 1:100 up to 1:16000, and the highest tested titres were for the L. Ballum, L. Tarassovi, L. Poi and L. Icterohaemorrhagiae. Vectors for the leptospirosys in our environments are mainly rodents (mice's and rats, wild mice's, and voles) that lives in the vicinity of the settlements and which represents natural reservoir of illness. Epidemiological researches, especially in the environments such as mines, as one of the natural reservoirs, can be a significant indicator of frequency and development and this disease, which is one of the reasons why we choose to explore characterictics of the leptospirosys epidemic in the Mine "Stara Jama" in Zenica, and based on results and experience take adequate preventive actions in order to prevent some future occurrence of similar epidemic.

Use of contraceptive methods and contraceptive recommendations among health care providers actively involved in contraceptive counseling -- results of an international survey in 10 countries.

PubMed

Gemzell-Danielsson, Kristina; Cho, SiHyun; Inki, Pirjo; Mansour, Diana; Reid, Robert; Bahamondes, Luis

2012-12-01

This study was conducted to determine the personal choices of contraceptive methods among an international sample of contraception health care professionals (HCPs) and to determine if these choices are concordant with their recommendations to women. In an anonymous online survey, 1001 HCPs actively involved in contraceptive counseling [obstetrician/gynecologists (OB/GYNs), general practitioners (GPs) and midwives (only in Sweden)] from 10 countries (Australia, Brazil, Canada, France, Germany, Korea, Mexico, Spain, Sweden and the United Kingdom) were asked about their personal use of contraceptive methods and their recommendations to women in two different clinical scenarios: for spacing between children (Group A) and after completion of the family (Group B). The largest HCP group was OB/GYNs (67.1%), followed by GPs (31.4%) and midwives (1.5%). A total of 42.7% of respondents were male, and 57.3% were female. The majority of respondents were aged 36-45 years (38.9%) or 46-55 years (42.8%), 79.7% had children, and 53.9% were currently using contraception (by themselves or by their partners). Among 540 contraceptive users, the three most common methods were the levonorgestrel-releasing intrauterine system (LNG-IUS; 29.3%), combined oral contraceptives (COCs; 20.0%) and condoms (17.0%). OB/GYNs were more likely to be using the LNG-IUS than GPs (p=.014). Gender did not seem to influence contraceptive preference. Reasons for these choices were largely influenced by family situation and high contraceptive efficacy (for the LNG-IUS) or side effects caused by other methods (for condoms). The top contraceptive recommendation was COCs for Group A and the LNG-IUS for Group B. HCPs currently using COCs and the LNG-IUS were more likely to recommend these methods than other contraceptive methods for Group A and Group B, respectively. The most popular contraceptive method in this sample of HCPs was the LNG-IUS. Choice of contraceptive method was driven by family situation, age and profession. It appears that, in this sample, personal contraceptive use influences contraceptive recommendations. Copyright © 2012 Elsevier Inc. All rights reserved.

Fair Shares and Sharing Fairly: A Survey of Public Views on Open Science, Informed Consent and Participatory Research in Biobanking.

PubMed

Joly, Yann; Dalpé, Gratien; So, Derek; Birko, Stanislav

2015-01-01

Biobanks are important resources which enable large-scale genomic research with human samples and data, raising significant ethical concerns about how participants' information is managed and shared. Three previous studies of the Canadian public's opinion about these topics have been conducted. Building on those results, an online survey representing the first study of public perceptions about biobanking spanning all Canadian provinces was conducted. Specifically, this study examined qualitative views about biobank objectives, governance structure, control and ownership of samples and data, benefit sharing, consent practices and data sharing norms, as well as additional questions and ethical concerns expressed by the public. Over half the respondents preferred to give a one-time general consent for the future sharing of their samples among researchers. Most expressed willingness for their data to be shared with the international scientific community rather than used by one or more Canadian institutions. Whereas more respondents indicated a preference for one-time general consent than any other model of consent, they constituted less than half of the total responses, revealing a lack of consensus among survey respondents regarding this question. Respondents identified biobank objectives, governance structure and accountability as the most important information to provide participants. Respondents' concerns about biobanking generally centred around the control and ownership of biological samples and data, especially with respect to potential misuse by insurers, the government and other third parties. Although almost half the respondents suggested that these should be managed by the researchers' institutions, results indicate that the public is interested in being well-informed about these projects and suggest the importance of increased involvement from participants. In conclusion, the study discusses the viability of several proposed models for informed consent, including e-governance, independent trustees and the use of exclusion clauses, in the context of these new findings about the views of the Canadian public.

Prevalence and patterns of smoking, alcohol use, and illicit drug use in young men who have sex with men.

PubMed

Newcomb, Michael E; Ryan, Daniel T; Greene, George J; Garofalo, Robert; Mustanski, Brian

2014-08-01

Young men who have sex with men (YMSM) are substantially more likely to use illicit drugs and other substances compared to their heterosexual peers. Substance use during adolescence has critical implications for long-term physical and mental health, and among YMSM may lead to HIV infection. The goal of the current study was to describe lifetime and past six month prevalence and patterns of substance use across multiple substances in a community sample of racially-diverse YMSM. Participants were 450 YMSM aged 16-20 living in Chicago and surrounding areas who were recruited beginning December, 2009 using a modified form of respondent driven sampling. Analyses were conducted with multivariate logistic regression and latent class analysis (LCA). Prevalence of substance use was high in this sample of majority racial minority YMSM, and only 17.6% reported no substance use during the past six months. Black YMSM had lower prevalence of use of all substances except marijuana compared to White YMSM, while Latino YMSM had lower prevalence of alcohol, marijuana, and club drug use. Bisexual YMSM reported higher prevalence of cigarette smoking, stimulant use, and club drug use compared to gay/mostly gay YMSM but lower numbers of bisexual participants limited the ability to detect statistically significant differences. LCA found that YMSM fell into three general categories of substance users: alcohol and marijuana users, polysubstance users, and low marijuana users. Analyses reveal important group differences in prevalence and patterns of substance use in YMSM that have important implications for intervention. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Local versus landscape spatial influence on biodiversity: a case study across five European industrialized areas.

PubMed

Piano, E; Isaia, M; Falasco, E; La Morgia, V; Soldato, G; Bona, F

2017-03-01

Land use change-mostly habitat loss and fragmentation-has been recognized as one of the major drivers of biodiversity loss worldwide. According to the habitat amount hypothesis, these phenomena are mostly driven by the habitat area effect. As a result, species richness is a function of both the extent of suitable habitats and their availability in the surrounding landscape, irrespective of the dimension and isolation of patches of suitable habitat. In this context, we tested how the extent of natural areas, selected as proxies of suitable habitats for biodiversity, influences species richness in highly anthropogenic landscapes. We defined five circular sampling areas of 5 km radius, including both natural reserves and anthropogenic land uses, centred in five major industrial sites in France, Italy and Germany. We monitored different biodiversity indicators for both terrestrial and aquatic ecosystems, including breeding birds, diurnal butterflies, grassland vegetation, odonata, amphibians, aquatic plants and benthic diatoms. We studied the response of the different indicators to the extent of natural land uses in the sampling area (local effect) and in the surrounding landscape (landscape effect), identified as a peripheral ring encircling the sampling area. Results showed a positive response of five out of seven biodiversity indicators, with aquatic plants and odonata responding positively to the local effect, while birds, vegetation and diatoms showed a positive response to the landscape effect. Diatoms also showed a significant combined response to both effects. We conclude that surrounding landscapes act as important biodiversity sources, increasing the local biodiversity in highly anthropogenic contexts.

Lifetime Prevalence of Suicide Attempts Among Sexual Minority Adults by Study Sampling Strategies: A Systematic Review and Meta-Analysis.

PubMed

Hottes, Travis Salway; Bogaert, Laura; Rhodes, Anne E; Brennan, David J; Gesink, Dionne

2016-05-01

Previous reviews have demonstrated a higher risk of suicide attempts for lesbian, gay, and bisexual (LGB) persons (sexual minorities), compared with heterosexual groups, but these were restricted to general population studies, thereby excluding individuals sampled through LGB community venues. Each sampling strategy, however, has particular methodological strengths and limitations. For instance, general population probability studies have defined sampling frames but are prone to information bias associated with underreporting of LGB identities. By contrast, LGB community surveys may support disclosure of sexuality but overrepresent individuals with strong LGB community attachment. To reassess the burden of suicide-related behavior among LGB adults, directly comparing estimates derived from population- versus LGB community-based samples. In 2014, we searched MEDLINE, EMBASE, PsycInfo, CINAHL, and Scopus databases for articles addressing suicide-related behavior (ideation, attempts) among sexual minorities. We selected quantitative studies of sexual minority adults conducted in nonclinical settings in the United States, Canada, Europe, Australia, and New Zealand. Random effects meta-analysis and meta-regression assessed for a difference in prevalence of suicide-related behavior by sample type, adjusted for study or sample-level variables, including context (year, country), methods (medium, response rate), and subgroup characteristics (age, gender, sexual minority construct). We examined residual heterogeneity by using τ(2). We pooled 30 cross-sectional studies, including 21,201 sexual minority adults, generating the following lifetime prevalence estimates of suicide attempts: 4% (95% confidence interval [CI] = 3%, 5%) for heterosexual respondents to population surveys, 11% (95% CI = 8%, 15%) for LGB respondents to population surveys, and 20% (95% CI = 18%, 22%) for LGB respondents to community surveys (Figure 1). The difference in LGB estimates by sample type persisted after we accounted for covariates with meta-regression. Sample type explained 33% of the between-study variability. Regardless of sample type examined, sexual minorities had a higher lifetime prevalence of suicide attempts than heterosexual persons; however, the magnitude of this disparity was contingent upon sample type. Community-based surveys of LGB people suggest that 20% of sexual minority adults have attempted suicide. Accurate estimates of sexual minority health disparities are necessary for public health monitoring and research. Most data describing these disparities are derived from 2 sample types, which yield different estimates of the lifetime prevalence of suicide attempts. Additional studies should explore the differential effects of selection and information biases on the 2 predominant sampling approaches used to understand sexual minority health.

Data-driven sensor placement from coherent fluid structures

NASA Astrophysics Data System (ADS)

Manohar, Krithika; Kaiser, Eurika; Brunton, Bingni W.; Kutz, J. Nathan; Brunton, Steven L.

2017-11-01

Optimal sensor placement is a central challenge in the prediction, estimation and control of fluid flows. We reinterpret sensor placement as optimizing discrete samples of coherent fluid structures for full state reconstruction. This permits a drastic reduction in the number of sensors required for faithful reconstruction, since complex fluid interactions can often be described by a small number of coherent structures. Our work optimizes point sensors using the pivoted matrix QR factorization to sample coherent structures directly computed from flow data. We apply this sampling technique in conjunction with various data-driven modal identification methods, including the proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD). In contrast to POD-based sensors, DMD demonstrably enables the optimization of sensors for prediction in systems exhibiting multiple scales of dynamics. Finally, reconstruction accuracy from pivot sensors is shown to be competitive with sensors obtained using traditional computationally prohibitive optimization methods.

Acceleration of a ground-state reaction by selective femtosecond-infrared-laser-pulse excitation

NASA Astrophysics Data System (ADS)

Stensitzki, Till; Yang, Yang; Kozich, Valeri; Ahmed, Ashour A.; Kössl, Florian; Kühn, Oliver; Heyne, Karsten

2018-02-01

Infrared (IR) excitation of vibrations that participate in the reaction coordinate of an otherwise thermally driven chemical reaction are believed to lead to its acceleration. Attempts at the practical realization of this concept have been hampered so far by competing processes leading to sample heating. Here we demonstrate, using femtosecond IR-pump IR-probe experiments, the acceleration of urethane and polyurethane formation due to vibrational excitation of the reactants for 1:1 mixtures of phenylisocyanate and cyclohexanol, and toluene-2,4-diisocyanate and 2,2,2-trichloroethane-1,1-diol, respectively. We measured reaction rate changes upon selective vibrational excitation with negligible heating of the sample and observed an increase of the reaction rate up to 24%. The observation is rationalized using reactant and transition-state structures obtained from quantum chemical calculations. We subsequently used IR-driven reaction acceleration to write a polyurethane square on sample windows using a femtosecond IR pulse.

"Under the radar": nurse practitioner prescribers and pharmaceutical industry promotions.

PubMed

Ladd, Elissa C; Mahoney, Diane Feeney; Emani, Srinivas

2010-12-01

To assess nurse practitioners' interactions with pharmaceutical industry promotional activities and their perception of information reliability and self-reported prescribing behaviors. Self-administered online survey. A nationally randomized sample of nurse practitioner prescribers was surveyed. Eligibility criteria included current clinical practice and licensure to prescribe medications in their state of practice. A total of 263 responses were analyzed. Almost all respondents (96%) reported regular contact with pharmaceutical sales representatives, and most (71%) reported receiving information on new drugs directly from pharmaceutical sales representatives some or most of the time. A large portion (66%) dispensed drug samples regularly to their patients, and 73% believed that samples were somewhat or very helpful in learning about new drugs. Eighty-one percent of respondents thought that it was ethically acceptable to give out samples to anyone, and 90% believed that it was acceptable to attend lunch and dinner events sponsored by the pharmaceutical industry. Almost half (48%) stated that they were more likely to prescribe a drug that was highlighted during a lunch or dinner event. Most respondents stated that it was ethically acceptable for speakers to be paid by industry. Nurse practitioner prescribers had extensive contact with pharmaceutical industry promotional activities such as pharmaceutical representative contact, receipt of drug samples, and regular attendance at industry-sponsored meal events and continuing education programs. They reported that industry interface with nurse practitioner prescribers in the form of sponsored meals, education events, and paid speakers was ethically acceptable.

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

PubMed

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

2017-01-01

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

Climate-driven changes in functional biogeography of Arctic marine fish communities

PubMed Central

Primicerio, Raul; Kortsch, Susanne; Aune, Magnus; Dolgov, Andrey V.; Fossheim, Maria; Aschan, Michaela M.

2017-01-01

Climate change triggers poleward shifts in species distribution leading to changes in biogeography. In the marine environment, fish respond quickly to warming, causing community-wide reorganizations, which result in profound changes in ecosystem functioning. Functional biogeography provides a framework to address how ecosystem functioning may be affected by climate change over large spatial scales. However, there are few studies on functional biogeography in the marine environment, and none in the Arctic, where climate-driven changes are most rapid and extensive. We investigated the impact of climate warming on the functional biogeography of the Barents Sea, which is characterized by a sharp zoogeographic divide separating boreal from Arctic species. Our unique dataset covered 52 fish species, 15 functional traits, and 3,660 stations sampled during the recent warming period. We found that the functional traits characterizing Arctic fish communities, mainly composed of small-sized bottom-dwelling benthivores, are being rapidly replaced by traits of incoming boreal species, particularly the larger, longer lived, and more piscivorous species. The changes in functional traits detected in the Arctic can be predicted based on the characteristics of species expected to undergo quick poleward shifts in response to warming. These are the large, generalist, motile species, such as cod and haddock. We show how functional biogeography can provide important insights into the relationship between species composition, diversity, ecosystem functioning, and environmental drivers. This represents invaluable knowledge in a period when communities and ecosystems experience rapid climate-driven changes across biogeographical regions. PMID:29087943

Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid.

PubMed

Salt, A N; Gill, R M; Hartsock, J J

2015-06-01

Understanding how drugs are distributed in perilymph following local applications is important as local drug therapies are increasingly used to treat disorders of the inner ear. The potential contribution of cerebrospinal fluid (CSF) entry to perilymph homeostasis has been controversial for over half a century, largely due to artifactual contamination of collected perilymph samples with CSF. Measures of perilymph flow and of drug distribution following round window niche applications have both suggested a slow, apically directed flow occurs along scala tympani (ST) in the normal, sealed cochlea. In the present study, we have used fluorescein isothiocyanate-dextran as a marker to study perilymph kinetics in guinea pigs. Dextran is lost from perilymph more slowly than other substances so far quantified. Dextran solutions were injected from pipettes sealed into the lateral semicircular canal (SCC), the cochlear apex, or the basal turn of ST. After varying delays, sequential perilymph samples were taken from the cochlear apex or lateral SCC, allowing dextran distribution along the perilymphatic spaces to be quantified. Variability was low and findings were consistent with the injection procedure driving volume flow towards the cochlear aqueduct, and with volume flow during perilymph sampling driven by CSF entry at the aqueduct. The decline of dextran with time in the period between injection and sampling was consistent with both a slow volume influx of CSF (~30 nL/min) entering the basal turn of ST at the cochlear aqueduct and a CSF-perilymph exchange driven by pressure-driven fluid oscillation across the cochlear aqueduct. Sample data also allowed contributions of other processes, such as communications with adjacent compartments, to be quantified. The study demonstrates that drug kinetics in the basal turn of ST is complex and is influenced by a considerable number of interacting processes.

[Socioeconomic status and risky health behaviors in Croatian adult population].

PubMed

Pilić, Leta; Dzakula, Aleksandar

2013-03-01

Based on the previous research, there is strong association between low socioeconomic status (SES) and high morbidity and mortality rates. Even though association between SES and risky health behaviors as the main factors influencing health has been investigated in Croatian population, some questions are yet to be answered. The aim of this study was to investigate the presence of unhealthy diet, physical inactivity, smoking and excessive drinking in low, middle, and high socioeconomic group of adult Croatian population included in the cohort study on regionalism of cardiovascular health risk behaviors. We also investigated the association between SES measured by income, education and occupation, as well as single SES indicators, and risky health behaviors. We analyzed data on 1227 adult men and women (aged 19 and older at baseline) with complete data on health behaviors, SES and chronic diseases at baseline (2003) and 5-year follow up. Respondents were classified as being healthy or chronically ill. SES categories were derived from answers to questions on monthly household income, occupation and education by using two-step cluster analysis algorithm. At baseline, for the whole sample as well as for healthy respondents, SES was statistically significantly associated with unhealthy diet (whole sample/healthy respondents: p = 0.001), physical inactivity (whole sample/healthy respondents p = 0.44/ p = 0.007), and smoking (whole sample/healthy respondents p < 0.001/p = 0.002). The proportion of respondents with unhealthy diet was greatest in the lowest social class, smokers in the middle and physically inactive in the high social class. During the follow up, smoking and physical inactivity remained statistically significantly associated with SES. In chronically ill respondents, only smoking was statistically significantly associated with SES, at baseline and follow up (p = 0.001/p = 0.002). The highest share of smokers was in the middle social class. Results of our study show that risky health behaviors are associated with SES and are divergently represented across socioeconomic groups of adult Croatian population. There is an obvious need for interventions targeting the specific socioeconomic group and behavior characteristic of that group.

Point and Click, Carefully: Investigating Inconsistent Response Styles in Middle School and College Students Involved in Web-Based Longitudinal Substance Use Research

PubMed Central

Wardell, Jeffrey D.; Rogers, Michelle L.; Simms, Leonard J.; Jackson, Kristina M.; Read, Jennifer P.

2014-01-01

This study investigated inconsistent responding to survey items by participants involved in longitudinal, web-based substance use research. We also examined cross-sectional and prospective predictors of inconsistent responding. Middle school (N = 1,023) and college students (N = 995) from multiple sites in the United States responded to online surveys assessing substance use and related variables in three waves of data collection. We applied a procedure for creating an index of inconsistent responding at each wave that involved identifying pairs of items with considerable redundancy and calculating discrepancies in responses to these items. Inconsistent responding was generally low in the Middle School sample and moderate in the College sample, with individuals showing only modest stability in inconsistent responding over time. Multiple regression analyses identified several baseline variables—including demographic, personality, and behavioral variables—that were uniquely associated with inconsistent responding both cross-sectionally and prospectively. Alcohol and substance involvement showed some bivariate associations with inconsistent responding, but these associations largely were accounted for by other factors. The results suggest that high levels of carelessness or inconsistency do not appear to characterize participants’ responses to longitudinal web-based surveys of substance use and support the use of inconsistency indices as a tool for identifying potentially problematic responders. PMID:24092819

Analysis of cattle breeder’s income in South Kualuh sub-district of Labuhan Batu Utara Regency

NASA Astrophysics Data System (ADS)

Hasnudi; Berutu, I. S.; Daulay, A. H.; Ginting, N.; Sembiring, I.

2018-02-01

Beef cattle breeding is a business of the majority people in South Kualuh Subdistrict among others business. Therefore it is necessary to know the people income of beef cattle farms in the district. This research was conducted in South Kualuh Subdistrict of Labuhan Batu Utara Regency of North Sumatera Province from October to December 2016. This research used survey method with family respondent unit that raising beef cattle. The sample was obtained through Proportional Stratified Random Sampling method and obtained by 97 farmers such as, from Tanjung Pasir village, 64 respondents, Simangalam village was 24 respondents and Lobu Huala village was 9 respondents. Data was analysed by multiple linear regression analysis. The results showed that scale of business, education of farmers positively affect the income of beef cattle farms while the age, breeding experience and the number of family dependents negatively affect to the income of beef cattle farms.

Reflections of College Students about the Use of Classical Relaxing Harp Music in the Student Lounge

ERIC Educational Resources Information Center

Pelayo, Jose Maria G., III.; Jao, Rodolfo V.; Pelayo, Jose Juancho S.

2014-01-01

The research study involved sixty one (61) respondents (20 male and 41 females) Convenience sampling was used to select the respondents. All of the respondents are students of Systems Plus College Foundation taking up the subject General Psychology. Average age of the respondents is 18 years old. Based on the gathered data, all of the respondents…

A national survey of clinical pharmacy services in county hospitals in China.

PubMed

Yao, Dongning; Xi, Xiaoyu; Huang, Yuankai; Hu, Hao; Hu, Yuanjia; Wang, Yitao; Yao, Wenbing

2017-01-01

Clinical pharmacy is not only a medical science but also an elaborate public health care system firmly related to its subsystems of education, training, qualification authentication, scientific research, management, and human resources. China is a developing country with a tremendous need for improvements in the public health system, including the clinical pharmacy service system. The aim of this research was to evaluate the infrastructure and personnel qualities of clinical pharmacy services in China. Public county hospitals in China. A national survey of clinical pharmacists in county hospitals was conducted. It was sampled through a stratified sampling strategy. Responses were analyzed using descriptive and inferential statistics. The main outcome measures include the coverage of clinical pharmacy services, the overall staffing of clinical pharmacists, the software and hardware of clinical pharmacy services, the charge mode of clinical pharmacy services, and the educational background, professional training acquisition, practical experience, and entry path of clinical pharmacists. The overall coverage of clinical pharmacy services on both the department scale (median = 18.25%) and the patient scale (median = 15.38%) does not meet the 100% coverage that is required by the government. In 57.73% of the sample hospitals, the staffing does not meet the requirement, and the size of the clinical pharmacist group is smaller in larger hospitals. In addition, 23.4% of the sample hospitals do not have management rules for the clinical pharmacists, and 43.1% do not have rational drug use software, both of which are required by the government. In terms of fees, 89.9% of the sample hospitals do not charge for the services. With regard to education, 8.5% of respondents are with unqualified degree, and among respondents with qualified degree, 37.31% are unqualified in the major; 43% of respondents lack the clinical pharmacist training required by the government. Most respondents (93.5%) have a primary or medium professional title. The median age and work seniority of respondents are 31 and four years, respectively. Only 18.5% of respondents chose this occupation by personal consideration or willingness. The main findings in this research include the overall low coverage of clinical pharmacy services, the low rate of clinical pharmacy service software, hardware, and personnel as well as a wide variance in educational training of pharmacists at county hospitals.

75 FR 38774 - Submission for OMB Review; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-06

... design research as part of testing for its censuses and surveys. At this time, the Census Bureau is... follows: Field test, Respondent debriefing questionnaire, Split sample experiments, Cognitive interviews... each round will be provided separately. When split sample experiments are conducted, either in small...

Facebook and Twitter, communication and shelter, and the 2011 Tuscaloosa tornado.

PubMed

Stokes, Courtney; Senkbeil, Jason C

2017-01-01

This paper represents one of the first attempts to analyse the many ways in which Facebook and Twitter were used during a tornado disaster. Comparisons between five randomly selected campus samples and a city of Tuscaloosa, Alabama, sample revealed that campus samples used Facebook and Twitter significantly more both before and after the tornado, but Facebook usage was not significantly different after the event. Furthermore, differences in social media usage and other forms of communication before the tornado were found for age, education, and years lived in Tuscaloosa. Generally, age and education were inversely proportionate to social media usage. Influences on shelter-seeking actions varied between social media users and three random samples of non-social media users; however, it appears that social media respondents were likely to be using a smartphone simultaneously to access warning polygon information, to receive text message alerts, and to listen or respond to environmental cues. © 2017 The Author(s). Disasters © Overseas Development Institute, 2017.

An exploratory study of differences in views of factors affecting sexual orientation for a sample of lesbians and gay men.

PubMed

Otis, Melanie D; Skinner, William F

2004-06-01

An exploratory study of lesbians (70) and gay men (118) from a rural state in the mid-South was conducted using a self-administered, mail-out survey. The nonrandom sample was drawn from organizational mailing lists, snowball sampling, and a convenience sample at a community event. Respondents were asked to indicate the extent to which each of the following affected sexual orientation: genetics, relationship between parents, relationship with parents, birth order, peers, growing up in a dysfunctional family, growing up in a single-parent family, negative experiences with the opposite sex, and positive experiences with the same sex. Similar to studies of heterosexual men and women, these gay men were more likely to view sexual orientation as a result of genetics than the lesbian respondents. Further, the lesbian group were more likely to view positive relationships with the same sex to have a great influence on sexual orientation. These data indicate there are sex differences in views on factors that affect sexual orientation.

Quality of life of the Indonesian general population: Test-retest reliability and population norms of the EQ-5D-5L and WHOQOL-BREF.

PubMed

Purba, Fredrick Dermawan; Hunfeld, Joke A M; Iskandarsyah, Aulia; Fitriana, Titi Sahidah; Sadarjoen, Sawitri S; Passchier, Jan; Busschbach, Jan J V

2018-01-01

The objective of this study is to obtain population norms and to assess test-retest reliability of EQ-5D-5L and WHOQOL-BREF for the Indonesian population. A representative sample of 1056 people aged 17-75 years was recruited from the Indonesian general population. We used a multistage stratified quota sampling method with respect to residence, gender, age, education level, religion and ethnicity. Respondents completed EQ-5D-5L and WHOQOL-BREF with help from an interviewer. Norms data for both instruments were reported. For the test-retest evaluations, a sub-sample of 206 respondents completed both instruments twice. The total sample and test-retest sub-sample were representative of the Indonesian general population. The EQ-5D-5L shows almost perfect agreement between the two tests (Gwet's AC: 0.85-0.99 and percentage agreement: 90-99%) regarding the five dimensions. However, the agreement of EQ-VAS and index scores can be considered as poor (ICC: 0.45 and 0.37 respectively). For the WHOQOL-BREF, ICCs of the four domains were between 0.70 and 0.79, which indicates moderate to good agreement. For EQ-5D-5L, it was shown that female and older respondents had lower EQ-index scores, whilst rural, younger and higher-educated respondents had higher EQ-VAS scores. For WHOQOL-BREF: male, younger, higher-educated, high-income respondents had the highest scores in most of the domains, overall quality of life, and health satisfaction. This study provides representative estimates of self-reported health status and quality of life for the general Indonesian population as assessed by the EQ-5D-5L and WHOQOL-BREF instruments. The descriptive system of the EQ-5D-5L and the WHOQOL-BREF have high test-retest reliability while the EQ-VAS and the index score of EQ-5D-5L show poor agreement between the two tests. Our results can be useful to researchers and clinicians who can compare their findings with respect to these concepts with those of the Indonesian general population.

A Gas-Spring-Loaded X-Y-Z Stage System for X-ray Microdiffraction Sample Manipulation

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

Shu Deming; Cai Zhonghou; Lai, Barry

2007-01-19

We have designed and constructed a gas-spring-loaded x-y-z stage system for x-ray microdiffraction sample manipulation at the Advanced Photon Source XOR 2-ID-D station. The stage system includes three DC-motor-driven linear stages and a gas-spring-based heavy preloading structure, which provides antigravity forces to ensure that the stage system keeps high-positioning performance under variable goniometer orientation. Microdiffraction experiments with this new stage system showed significant sample manipulation performance improvement.

A Gas-Spring-Loaded X-Y-Z Stage System for X-ray Microdiffraction Sample Manipulation

NASA Astrophysics Data System (ADS)

Shu, Deming; Cai, Zhonghou; Lai, Barry

2007-01-01

We have designed and constructed a gas-spring-loaded x-y-z stage system for x-ray microdiffraction sample manipulation at the Advanced Photon Source XOR 2-ID-D station. The stage system includes three DC-motor-driven linear stages and a gas-spring-based heavy preloading structure, which provides antigravity forces to ensure that the stage system keeps high-positioning performance under variable goniometer orientation. Microdiffraction experiments with this new stage system showed significant sample manipulation performance improvement.

Low-dose fixed-target serial synchrotron crystallography.

PubMed

Owen, Robin L; Axford, Danny; Sherrell, Darren A; Kuo, Anling; Ernst, Oliver P; Schulz, Eike C; Miller, R J Dwayne; Mueller-Werkmeister, Henrike M

2017-04-01

The development of serial crystallography has been driven by the sample requirements imposed by X-ray free-electron lasers. Serial techniques are now being exploited at synchrotrons. Using a fixed-target approach to high-throughput serial sampling, it is demonstrated that high-quality data can be collected from myoglobin crystals, allowing room-temperature, low-dose structure determination. The combination of fixed-target arrays and a fast, accurate translation system allows high-throughput serial data collection at high hit rates and with low sample consumption.

Juveniles' knowledge of the court process: results from instruction from an electronic source.

PubMed

Driver, Christine; Brank, Eve M

2009-01-01

Our study first determined what juveniles know about the juvenile court process. Second, it evaluated a DVD designed to be a systematic and simple way to improve this knowledge. A pre- and posttest design was used with two pilot samples and two samples from the population of interest. A sample from a juvenile detention center (n = 118) was the focus of this study. Initial knowledge of the court process was quite low for the detention sample (pretest M = 64.0%, SD = 14.2%). All samples experienced a significant improvement of knowledge after watching the DVD. Youth in the detention sample had a mean improvement from pretest to posttest of 6.4% (SD = 11.9%), with mean scores at posttest being 70.3% (SD = 17.4%). Respondents varied in their performance on different question topics, scoring the lowest on questions related to what happens at juvenile court hearings. The social and demographic variables of age, race, gender, grades in school, number of previous arrests, and the number of times the respondent had been to court were evaluated through regression analysis. Age and race were found to be significantly related to pretest scores, and race was significantly related to improvement scores. (c) 2009 John Wiley & Sons, Ltd.

Comparative performance of novel self-sampling methods in detecting high-risk human papillomavirus in 30,130 women not attending cervical screening.

PubMed

Bosgraaf, Remko P; Verhoef, Viola M J; Massuger, Leon F A G; Siebers, Albert G; Bulten, Johan; de Kuyper-de Ridder, Gabriëlle M; Meijer, Chris J M; Snijders, Peter J F; Heideman, Daniëlle A M; IntHout, Joanna; van Kemenade, Folkert J; Melchers, Willem J G; Bekkers, Ruud L M

2015-02-01

We determined whether the participation rate for a brush-based cervicovaginal self-sampling device is noninferior to the participation rate for a lavage-based one for testing for hrHPV (high-risk human papillomavirus). Additionally, positivity rates for hrHPV, the detection rates for cervical intraepithelial neoplasia grades 2 and 3 or worse (CIN2+/3+), and user comfort were compared. A total of 35,477 non-responders of the regular cervical screening program aged 33-63 years were invited to participate. Eligible women (n = 30,130) were randomly assigned to receive either a brush-based or a lavage-based device, and a questionnaire for reporting user convenience. Self-sampling responders testing hrHPV-positive were invited for a physician-taken sample for cytology; triage-positive women were referred for colposcopy. A total of 5,218 women participated in the brush-based sampling group (34.6%) and 4809 women in the lavage-based group (31.9%), i.e. an absolute difference of 2.7% (95%CI 1.8-4.2). The hrHPV-positivity rates in the two groups were identical (8.3%, relative risk (RR) 0.99, 95%CI 0.87-1.13). The detection of CIN2+ and CIN3+ in the brush group (2.0% for CIN2+; 1.3% for CIN3+) was similar to that in the lavage group (1.9% for CIN2+; 1.0% for CIN3+) with a cumulative RR of 1.01, 95%CI 0.83-1.24 for CIN2+ and 1.25, 95%CI 0.92-1.70 for CIN3+. The two self-sampling devices performed similarly in user comfort. In conclusion, offering a brush-based device to non-responders is noninferior to offering a lavage-based device in terms of participation. The two self-sampling methods are equally effective in detecting hrHPV, CIN2+/CIN3+ and are both well accepted. © 2014 UICC.

Attitudes of NICU professionals regarding feeding blood-tinged colostrum or milk.

PubMed

Phelps, M M; Bedard, W S; Henry, E; Christensen, S S; Gardner, R W; Karp, T; Wiedmeier, S E; Christensen, R D

2009-02-01

Mothers of neonatal intensive care unit (NICU) patients sometimes bring expressed milk that is blood tinged to the NICU. In certain instances, the blood contamination appears minimal, whereas in others, the milk is quite dark pink. We have observed inconsistencies in practice regarding whether or not to feed blood-tinged colostrum or milk to NICU patients. We know of no evidence that establishes best practice in this area, and thus we sought to determine attitudes of NICU professionals on which to base a potentially best practice. We conducted a web-based anonymous survey of attitudes of NICU professionals at Intermountain Healthcare regarding feeding blood-tinged expressed milk to NICU patients. These professionals included neonatologists, neonatal nurse practitioners, NICU nurses, NICU dieticians and lactation consultants. Survey results were returned from 64% (426 of 667) of those to whom it was sent. A total of 75% of respondents reported that their practice was NOT to feed the blood-tinged milk illustrated in the figure as sample 2, and nearly all respondents (98%) reported that they would NOT feed the milk illustrated as sample 3. The majority of the neonatologists (56%) and the lactation consultants (58%) recommended feeding moderately bloody milk (sample 2), whereas only 22% of the neonatal nurse practitioners (NNPs), NICU nurses and NICU dieticians recommended feeding such samples (<0.001). The most frequently selected reason for NOT feeding blood-tinged milk was that it would likely cause gastrointestinal upset and feeding intolerance (selected by 77%). The majority (87%) overestimated the amount of blood contaminating a milk sample (sample 3). As colostrum and human milk feedings can be of value to NICU patients, evidence should be assembled to document whether feeding blood-tinged samples indeed have the problems listed by the survey respondents. Such evidence is needed to enable informed decisions involving the benefits vs risks of feeding blood-tinged expressed milk to NICU patients.

HPV self-sampling in Japanese women: A feasibility study in a population with limited experience of tampon use.

PubMed

Hanley, Sharon Jb; Fujita, Hiromasa; Yokoyama, Susumu; Kunisawa, Shiori; Tamakoshi, Akiko; Dong, Peixin; Kobayashi, Noriko; Watari, Hidemichi; Kudo, Masataka; Sakuragi, Noriaki

2016-09-01

Cervical cancer incidence and mortality is increasing in Japanese women under age 50. Screening uptake is low and proactive recommendations for human papillomavirus vaccination have been suspended. Other cervical cancer prevention initiatives are urgently needed. We assessed whether human papillomavirus self-sampling might be an acceptable alternative to physician-led screening, particularly in women with limited experience of tampon use. We also sought to identify any practical, logistical, or safety issues in women already attending for screening, before carrying out further large-scale studies in non-responders. In total, 203 women aged 20-49 attending their annual workplace healthcheck in Sapporo, northern Japan, performed unsupervised human papillomavirus self-sampling before undergoing a physician-led cervical smear and human papillomavirus test, and completing a measure of acceptability for both tests. Ninety per cent of participants stated they would use self-sampling again. They found instructions easy to follow and reported no issues with the usability of the self-sampling device. Compared with physician-led testing, women found self-sampling significantly less painful, less embarrassing and could relax more (p < 0.001), regardless of history of tampon use, which was associated with negative experiences in physician sampling (p = 0.034). Women lacked confidence the test had been performed correctly, despite no unsatisfactory samples. No safety issues were reported. Self-sampling was highly acceptable in this population of women. They could perform the test safely unsupervised, but lacked confidence the test has been carried out correctly. Japanese women need to be educated about the accuracy of human papillomavirus self-sampling and further large-scale studies are necessary in non-responders. © The Author(s) 2016.

Public perceptions, knowledge and awareness of cholesterol management in Singapore: a prospective pilot study.

PubMed

Aung, Than Htike; Go, Yun Yun; Low, Lip Ping; Chua, Terrance

2013-01-01

Hyperlipidaemia is a major risk factor for coronary artery disease (CAD). Its effective treatment has been shown to reduce the incidence of cardiovascular events, both in secondary and primary prevention. An essential component of risk factor management at the community level is public awareness and knowledge of treatment benefits. However, this data is limited in Singapore. A cross-sectional survey questionnaire of public perception and knowledge on cholesterol treatment among adult Singaporeans aged 30-69 years was commissioned by the Singapore Heart Foundation and conducted by a professional market survey company. Regional quota sampling was performed to ensure that the sample was representative of the Singapore population. This was followed by random sampling of households and respondents. Of the 365 respondents, 40.9% were male, 70.3% were Chinese, 18.8% Malay and 10.9% Indian. The mean age was 47.5 years. Although 81.9% of respondents had medical check-ups involving blood tests, only 11.0% knew their actual cholesterol levels. A third of the respondents saw herbal medicine as healthier and safer than Western medication. More than 80% of respondents believed that diet and exercise were equally effective at lowering cholesterol as medication. About half of the respondents associated long-term use of statins with damage to the liver and kidney, while a third associated chronic statin use with the development of cancer. There are gaps in the level of public awareness and understanding of cholesterol treatment in Singapore. Common misconceptions should be addressed, as they could potentially impair effective management or treatment compliance.

Note: A sample holder design for sensitive magnetic measurements at high temperatures in a magnetic properties measurement system

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

Arauzo, A.; Guerrero, E.; Urtizberea, A.

2012-06-15

A sample holder design for high temperature measurements in a commercial MPMS SQUID magnetometer from Quantum Design is presented. It fulfills the requirements for the simultaneous use of the oven and reciprocating sample option (RSO) options, thus allowing sensitive magnetic measurements up to 800 K. Alternating current susceptibility can also be measured, since the holder does not induce any phase shift relative to the ac driven field. It is easily fabricated by twisting Constantan Copyright-Sign wires into a braid nesting the sample inside. This design ensures that the sample be placed tightly into a tough holder with its orientation fixed,more » and prevents any sample displacement during the fast movements of the RSO transport, up to high temperatures.« less

Awareness and uptake of direct-to-consumer genetic testing among cancer cases, their relatives, and controls: the Northwest Cancer Genetics Network.

PubMed

Hall, Taryn O; Renz, Anne D; Snapinn, Katherine W; Bowen, Deborah J; Edwards, Karen L

2012-07-01

To determine if awareness of, interest in, and use of direct-to-consumer (DTC) genetic testing is greater in a sample of high-risk individuals (cancer cases and their relatives), compared to controls. Participants were recruited from the Northwest Cancer Genetics Network. A follow-up survey was mailed to participants to assess DTC genetic testing awareness, interest, and use. One thousand two hundred sixty-seven participants responded to the survey. Forty-nine percent of respondents were aware of DTC genetic testing. Of those aware, 19% indicated interest in obtaining and <1% reported having used DTC genetic testing. Additional information supplied by respondents who reported use of DTC genetic tests indicated that 55% of these respondents likely engaged in clinical genetic testing, rather than DTC genetic testing. Awareness of DTC genetic testing was greater in our sample of high-risk individuals than in controls and population-based studies. Although interest in and use of these tests among cases in our sample were equivalent to other population-based studies, interest in testing was higher among relatives and people who self-referred for a registry focused on cancer than among cases and controls. Additionally, our results suggest that there may be some confusion about what constitutes DTC genetic testing.

Variation in Major Depressive Disorder Onset by Place of Origin Among U.S. Latinos.

PubMed

Lee, Sungkyu; Park, Yangjin

2017-09-01

Using a nationally representative sample of 2514 U.S. Latinos, this study examined the extent to which major depressive disorder (MDD) onset differs by place of origin and the factors associated with it. The Kaplan-Meier method estimated the survival and hazard functions for MDD onset by place of origin, and Cox proportional hazards models identified its associative factors. Approximately 13% of the sample had experienced MDD in their lifetimes. Cuban respondents showed the highest survival function, while Puerto Ricans showed the lowest. With the entire sample, the smoothed hazard function showed that the risk of MDD onset peaked in the late 20s and early 80s. Puerto Rican respondents showed the highest risk of MDD during their 20s and 30s, whereas Cuban respondents showed a relatively stable pattern over time. The results from the Cox proportional hazards model indicated that age, sex, and marital status were significantly related to MDD onset (p < .05). In addition, the effect of U.S.-born status on MDD onset was greater among Mexican respondents than among Puerto Ricans. Findings from the present study demonstrate that different Latino subgroups experience different and unique patterns of MDD onset over time. Future research should account for the role of immigration status in examining MDD onset.

Reasons for nonresponse in a web-based survey of alcohol involvement among first-year college students.

PubMed

Cranford, James A; McCabe, Sean Esteban; Boyd, Carol J; Slayden, Janie; Reed, Mark B; Ketchie, Julie M; Lange, James E; Scott, Marcia S

2008-01-01

This study conducted a follow-up telephone survey of a probability sample of college students who did not respond to a Web survey to determine correlates of and reasons for nonresponse. A stratified random sample of 2502 full-time first-year undergraduate students was invited to participate in a Web-based survey. A random sample of 221 students who did not respond to the original Web survey completed an abbreviated version of the original survey by telephone. Nonresponse did not vary by gender, but nonresponse was higher among Blacks and Hispanics compared to Whites, and Blacks compared to Asians. Nonresponders reported lower frequency of past 28 days drinking, lower levels of past-year and past 28-days heavy episodic drinking, and more time spent preparing for classes than responders. The most common reasons for nonresponse were "too busy" (45.7%), "not interested" (18.1%), and "forgot to complete survey" (18.1%). Reasons for nonresponse to Web surveys among college students are similar to reasons for nonresponse to mail and telephone surveys, and some nonresponse reasons vary as a function of alcohol involvement.

River Flow Impacts Bacterial and Archaeal Community Structure in Surface Sediments in the Northern Gulf of Mexico.

PubMed

Ortmann, Alice C; Brannock, Pamela M; Wang, Lei; Halanych, Kenneth M

2018-04-17

Meiobenthic community structure in the northern Gulf of Mexico has been shown to be driven by geographical differences due to inshore-offshore gradients and location relative to river discharge. Samples collected along three transects spanning Mobile Bay, Alabama, showed significant differences in meiobenthic communities east of the bay compared to those sampled from the west. In contrast, analysis of bacterial and archaeal communities from the same sediment samples shows that the inshore-offshore gradient has minimal impact on their community structure. Significant differences in community structure were observed for Bacteria and Archaea between the east and west samples, but there was no difference in richness or diversity. Grouped by sediment type, higher richness was observed in silty samples compared to sandy samples. Significant differences were also observed among sediment types for community structure with bacteria communities in silty samples having more anaerobic sulfate reducers compared to aerobic heterotrophs, which had higher abundances in sandy sediments. This is likely due to increased organic matter in the silty sediments from the overlying river leading to low oxygen habitats. Most archaeal sequences represented poorly characterized high-level taxa, limiting interpretation of their distributions. Overlap between groups based on transect and sediment characteristics made determining which factor is more important in structuring bacterial and archaeal communities difficult. However, both factors are driven by discharge from the Mobile River. Although inshore-offshore gradients do not affect Bacteria or Archaea to the same extent as the meiobenthic communities, all three groups are strongly affected by sediment characteristics.

NHEXAS PHASE I MARYLAND STUDY--PESTICIDE METABOLITES IN URINE ANALYTICAL RESULTS

EPA Science Inventory

The Pesticide Metabolites in Urine data set contains analytical results for measurements of up to 9 pesticides in 345 urine samples over 79 households. Each sample was collected from the primary respondent within each household during the study and represented the first morning ...

NHEXAS PHASE I ARIZONA STUDY--PESTICIDE METABOLITES IN URINE ANALYTICAL RESULTS

EPA Science Inventory

The Pesticide Metabolites in Urine data set contains analytical results for measurements of up to 4 pesticide metabolites in 176 urine samples over 176 households. Each sample was collected from the primary respondent within each household during Stage III of the NHEXAS study. ...

Assessing the representativeness of physician and patient respondents to a primary care survey using administrative data.

PubMed

Li, Allanah; Cronin, Shawna; Bai, Yu Qing; Walker, Kevin; Ammi, Mehdi; Hogg, William; Wong, Sabrina T; Wodchis, Walter P

2018-05-30

QUALICOPC is an international survey of primary care performance. QUALICOPC data have been used in several studies, yet the representativeness of the Canadian QUALICOPC survey is unknown, potentially limiting the generalizability of findings. This study examined the representativeness of QUALICOPC physician and patient respondents in Ontario using health administrative data. This representativeness study linked QUALICOPC physician and patient respondents in Ontario to health administrative databases at the Institute for Clinical Evaluative Sciences. Physician respondents were compared to other physicians in their practice group and all Ontario primary care physicians on demographic and practice characteristics. Patient respondents were compared to other patients rostered to their primary care physicians, patients rostered to their physicians' practice groups, and a random sample of Ontario residents on sociodemographic characteristics, morbidity, and health care utilization. Standardized differences were calculated to compare the distribution of characteristics across cohorts. QUALICOPC physician respondents included a higher proportion of younger, female physicians and Canadian medical graduates compared to other Ontario primary care physicians. A higher proportion of physician respondents practiced in Family Health Team models, compared to the provincial proportion for primary care physicians. QUALICOPC patient respondents were more likely to be older and female, with significantly higher levels of morbidity and health care utilization, compared with the other patient groups examined. However, when looking at the QUALICOPC physicians' whole rosters, rather than just the patient survey respondents, the practice profiles were similar to those of the other physicians in their practice groups and Ontario patients in general. Comparisons revealed some differences in responding physicians' demographic and practice characteristics, as well as differences in responding patients' characteristics compared to the other patient groups tested, which may have resulted from the visit-based sampling strategy. Ontario QUALICOPC physicians had similar practice profiles as compared to non-participating physicians, providing some evidence that the participating practices are representative of other non-participating practices, and patients selected by visit-based sampling may also be representative of visiting patients in other practices. Those using QUALICOPC data should understand this limited representativeness when generalizing results, and consider the potential for bias in their analyses.

The Discrimination of Fully Randomized and Partially Randomized Responding from Nonrandomized Responding on the Sixteen Personality Factor Questionnaire-Fifth Edition

ERIC Educational Resources Information Center

Pietrzak, Dale; Korcuska, James S.

2007-01-01

This study examines the detection of various rates of noncontent responding on the Sixteen Personality Factor Questionnaire-Fifth Edition (R. Cattell, H. Eber, & M. Tatsuoka, 1970). The study used a sample of 237 adult volunteers. New scales were developed and tested. (Contains 3 tables.)

RESPONSE PROTOCOL TOOLBOX: PLANNING FOR AND RESPONDING TO DRINKING WATER CONTAMINATION THREATS AND INCIDENTS, MODULE 3: SITE CHARACTERIZATION AND SAMPLING GUIDE. INTERIM FINAL - DECEMBER 2003

EPA Science Inventory

The interim final Response Protocol Toolbox: Planning for and Responding to Contamination Threats to Drinking Water Systems is designed to help the water sector effectively and appropriately respond to intentional contamination threats and incidents. It was produced by EPA, buil...

Nanopipettes: probes for local sample analysis† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5sc00668f Click here for additional data file.

PubMed Central

Saha-Shah, Anumita; Weber, Anna E.; Karty, Jonathan A.; Ray, Steven J.; Hieftje, Gary M.

2015-01-01

Nanopipettes (pipettes with diameters <1 μm) were explored as pressure-driven fluid manipulation tools for sampling nanoliter volumes of fluids. The fundamental behavior of fluids confined in the narrow channels of the nanopipette shank was studied to optimize sampling volume and probe geometry. This method was utilized to collect nanoliter volumes (<10 nL) of sample from single Allium cepa cells and live Drosophila melanogaster first instar larvae. Matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was utilized to characterize the collected sample. The use of nanopipettes for surface sampling of mouse brain tissue sections was also explored. Lipid analyses were performed on mouse brain tissues with spatial resolution of sampling as small as 50 μm. Nanopipettes were shown to be a versatile tool that will find further application in studies of sample heterogeneity and population analysis for a wide range of samples. PMID:28706697

Environmental DNA sampling protocol - filtering water to capture DNA from aquatic organisms

USGS Publications Warehouse

Laramie, Matthew B.; Pilliod, David S.; Goldberg, Caren S.; Strickler, Katherine M.

2015-09-29

Environmental DNA (eDNA) analysis is an effective method of determining the presence of aquatic organisms such as fish, amphibians, and other taxa. This publication is meant to guide researchers and managers in the collection, concentration, and preservation of eDNA samples from lentic and lotic systems. A sampling workflow diagram and three sampling protocols are included as well as a list of suggested supplies. Protocols include filter and pump assembly using: (1) a hand-driven vacuum pump, ideal for sample collection in remote sampling locations where no electricity is available and when equipment weight is a primary concern; (2) a peristaltic pump powered by a rechargeable battery-operated driver/drill, suitable for remote sampling locations when weight consideration is less of a concern; (3) a 120-volt alternating current (AC) powered peristaltic pump suitable for any location where 120-volt AC power is accessible, or for roadside sampling locations. Images and detailed descriptions are provided for each step in the sampling and preservation process.

Recruiting and retaining youth and young adults: challenges and opportunities in survey research for tobacco control.

PubMed

Cantrell, Jennifer; Hair, Elizabeth C; Smith, Alexandria; Bennett, Morgane; Rath, Jessica Miller; Thomas, Randall K; Fahimi, Mansour; Dennis, J Michael; Vallone, Donna

2018-03-01

Evaluation studies of population-based tobacco control interventions often rely on large-scale survey data from numerous respondents across many geographic areas to provide evidence of their effectiveness. Significant challenges for survey research have emerged with the evolving communications landscape, particularly for surveying hard-to-reach populations such as youth and young adults. This study combines the comprehensive coverage of an address-based sampling (ABS) frame with the timeliness of online data collection to develop a nationally representative longitudinal cohort of young people aged 15-21. We constructed an ABS frame, partially supplemented with auxiliary data, to recruit this hard-to-reach sample. Branded and tested mail-based recruitment materials were designed to bring respondents online for screening, consent and surveying. Once enrolled, respondents completed online surveys every 6 months via computer, tablet or smartphone. Numerous strategies were utilized to enhance retention and representativeness RESULTS: Results detail sample performance, representativeness and retention rates as well as device utilization trends for survey completion among youth and young adult respondents. Panel development efforts resulted in a large, nationally representative sample with high retention rates. This study is among the first to employ this hybrid ABS-to-online methodology to recruit and retain youth and young adults in a probability-based online cohort panel. The approach is particularly valuable for conducting research among younger populations as it capitalizes on their increasing access to and comfort with digital communication. We discuss challenges and opportunities of panel recruitment and retention methods in an effort to provide valuable information for tobacco control researchers seeking to obtain representative, population-based samples of youth and young adults in the U.S. as well as across the globe. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Influence of alkalinity, hardness and dissolved solids on drinking water taste: A case study of consumer satisfaction.

PubMed

Lou, Jie-Chung; Lee, Wei-Li; Han, Jia-Yun

2007-01-01

Two surveys of consumer satisfaction with drinking water conducted by Taiwan Water Supply Corp. are presented in this study. The study results show that although a lot of money was invested to modify traditional treatment processes, over 60% of local residents still avoided drinking tap water. Over half of the respondents felt that sample TT (from the traditional treatment process) was not a good drinking water, whether in the first or second survey, whereas almost 60% of respondents felt that samples PA, PB, CCL and CT (from advanced treatment processes) were good to drink. For all drinking water samples, respondent satisfaction with a sample primarily depended on it having no unpleasant flavors. Taiwan Environmental Protection Administration plans to revise the drinking water quality standards for TH and TDS in the near future. The new standards require a lower TH concentration (from currently 400mg/L (as CaCO(3)) to 150mg/L (as CaCO(3))), and a lower TDS maximum admissible concentration from the current guideline of 600 to 250mg/L. Therefore, this study also evaluated the impacts on drinking water tastes caused by variations in TH and TDS concentrations, and assessed the need to issue more strict drinking water quality standards for TH and TDS. The research results showed that most respondents could not tell the difference in water taste among water samples with different TDS, TH and alkalinity. Furthermore, hardness was found to be inversely associated with cardiovascular diseases and cancers, and complying with more strict standards would lead most water facilities to invest billions of dollars to upgrade their treatment processes. Consequently, in terms of drinking water tastes alone, this study suggested that Taiwan Environmental Protection Administration should conduct more thorough reviews of the scientific literature that provides the rationale for setting standards and reconsider if it is necessary to revise drinking water quality standards for TH and TDS.

The Sampling Design of the China Family Panel Studies (CFPS)

PubMed Central

Xie, Yu; Lu, Ping

2018-01-01

The China Family Panel Studies (CFPS) is an on-going, nearly nationwide, comprehensive, longitudinal social survey that is intended to serve research needs on a large variety of social phenomena in contemporary China. In this paper, we describe the sampling design of the CFPS sample for its 2010 baseline survey and methods for constructing weights to adjust for sampling design and survey nonresponses. Specifically, the CFPS used a multi-stage probability strategy to reduce operation costs and implicit stratification to increase efficiency. Respondents were oversampled in five provinces or administrative equivalents for regional comparisons. We provide operation details for both sampling and weights construction. PMID:29854418

Determining the prevalence of intestinal parasites in three Orang Asli (Aborigines) communities in Perak, Malaysia.

PubMed

Sinniah, B; Sabaridah, I; Soe, M M; Sabitha, P; Awang, I P R; Ong, G P; Hassan, A K R

2012-06-01

This study was conducted to determine the prevalence of intestinal parasites among children and adult Orang Aslis (Aborigines) from different locations in Perak. Faecal samples were collected and analyzed using the direct smear and formal ether sedimentation technique. Some of the faecal samples were stained using the Modified Acid fast stain for Cryptosporidium. Nail clippings of the respondents and the soil around their habitat were also analyzed. Of the 77 stool samples examined, 39 (50.6%) were positive for at least one intestinal parasite. The most common parasite detected was Trichuris trichiura (39.0%) followed by Ascaris lumbricoides (26.9%), Entamoeba coli (5.2%), Giardia lamblia (5.2%), Blastocystis hominis (3.9%), hookworm (3.9%), Entamoeba histolytica (1.3%), Iodamoeba butschlii (1.3%) and Cryptosporidium sp. (1.3%) respectively. Some respondents had single parasites (24.7%), some with two parasites (18.2%). Some with three parasites (6.5%) and one had four parasites species (1.3%). The parasites were slightly more common in females (54.7%) than males ((41.7%). The parasites were more common in the 13-20 year age group (90.9%) followed by 1-12 years (69.6%), 21-40 year age group (34.8%) and least in the 41-60 year age group (27.8%). Nail examinations of the respondents did not show any evidence of parasites. One had a mite, three had pollen grains and one had yeast cells isolated from the finger nails. Soil samples taken around their houses showed only one sample with a nematode ova and one with oocyst which was of a non human origin.

Effects of major depression on moment-in-time work performance.

PubMed

Wang, Philip S; Beck, Arne L; Berglund, Pat; McKenas, David K; Pronk, Nicolaas P; Simon, Gregory E; Kessler, Ronald C

2004-10-01

Although major depression is thought to have substantial negative effects on work performance, the possibility of recall bias limits self-report studies of these effects. The authors used the experience sampling method to address this problem by collecting comparative data on moment-in-time work performance among service workers who were depressed and those who were not depressed. The group studied included 105 airline reservation agents and 181 telephone customer service representatives selected from a larger baseline sample; depressed workers were deliberately oversampled. Respondents were given pagers and experience sampling method diaries for each day of the study. A computerized autodialer paged respondents at random time points. When paged, respondents reported on their work performance in the diary. Moment-in-time work performance was assessed at five random times each day over a 7-day data collection period (35 data points for each respondent). Seven conditions (allergies, arthritis, back pain, headaches, high blood pressure, asthma, and major depression) occurred often enough in this group of respondents to be studied. Major depression was the only condition significantly related to decrements in both of the dimensions of work performance assessed in the diaries: task focus and productivity. These effects were equivalent to approximately 2.3 days absent because of sickness per depressed worker per month of being depressed. Previous studies based on days missed from work significantly underestimate the adverse economic effects associated with depression. Productivity losses related to depression appear to exceed the costs of effective treatment.

Development of an Inconsistent Responding Scale for the Triarchic Psychopathy Measure.

PubMed

Mowle, Elyse N; Kelley, Shannon E; Edens, John F; Donnellan, M Brent; Smith, Shannon Toney; Wygant, Dustin B; Sellbom, Martin

2017-08-01

Inconsistent or careless responding to self-report measures is estimated to occur in approximately 10% of university research participants and may be even more common among offender populations. Inconsistent responding may be a result of a number of factors including inattentiveness, reading or comprehension difficulties, and cognitive impairment. Many stand-alone personality scales used in applied and research settings, however, do not include validity indicators to help identify inattentive response patterns. Using multiple archival samples, the current study describes the development of an inconsistent responding scale for the Triarchic Psychopathy Measure (TriPM; Patrick, 2010), a widely used self-report measure of psychopathy. We first identified pairs of correlated TriPM items in a derivation sample (N = 2,138) and then created a total score based on the sum of the absolute value of the differences for each item pair. The resulting scale, the Triarchic Assessment Procedure for Inconsistent Responding (TAPIR), strongly differentiated between genuine TriPM protocols and randomly generated TriPM data (N = 1,000), as well as between genuine protocols and those in which 50% of the original data were replaced with random item responses. TAPIR scores demonstrated fairly consistent patterns of association with some theoretically relevant correlates (e.g., inconsistency scales embedded in other personality inventories), although not others (e.g., measures of conscientiousness) across our cross-validation samples. Tentative TAPIR cut scores that may discriminate between attentively and carelessly completed protocols are presented. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Flash Desorption/Mass Spectrometry for the Analysis of Less- and Nonvolatile Samples Using a Linearly Driven Heated Metal Filament

NASA Astrophysics Data System (ADS)

Usmanov, Dilshadbek T.; Ninomiya, Satoshi; Hiraoka, Kenzo

2013-11-01

In this paper, the important issue of the desorption of less- and nonvolatile compounds with minimal sample decomposition in ambient mass spectrometry is approached using ambient flash desorption mass spectrometry. The preheated stainless steel filament was driven down and up along the vertical axis in 0.3 s. At the lowest position, it touched the surface of the sample with an invasion depth of 0.1 mm in 50 ms (flash heating) and was removed from the surface (fast cooling). The heating rate corresponds to ~104 °C/s at the filament temperature of 500 °C. The desorbed gaseous molecules were ionized by using a dielectric barrier discharge ion source, and the produced ions were detected by a time-of-flight (TOF) mass spectrometer. Less-volatile samples, such as pharmaceutical tablets, narcotics, explosives, and C60 gave molecular and protonated molecule ions as major ions with thermal decomposition minimally suppressed. For synthetic polymers (PMMA, PLA, and PS), the mass spectra reflected their backbone structures because of the suppression of the sequential thermal decompositions of the primary products. The present technique appears to be suitable for high-throughput qualitative analyses of many types of solid samples in the range from a few ng to 10 μg with minimal sample consumption. Some contribution from tribodesorption in addition to thermal desorption was suggested for the desorption processes. [Figure not available: see fulltext.

NATIONAL RESPONSE TEAM TECHNICAL ASSISTANCE ...

EPA Pesticide Factsheets

This document provides technical information on a wide range of activities to aid in response to intentional release of anthrax in urban environments. It includes initial actions when a potential release is discovered, health and safety issues for responders, sampling and analysis methods, decontamination technologies, decontamination waste disposal, and communication with public. This document provides technical information on a wide range of activities to aid in response to intentional release of anthrax in urban environments. It includes initial actions when a potential release is discovered, health and safety issues for responders, sampling and analysis methods, decontamination technologies, decontamination waste disposal, and communication with public.

Depression and HIV risk among men who have sex with men in Tanzania.

PubMed

Ahaneku, Hycienth; Ross, Michael W; Nyoni, Joyce E; Selwyn, Beatrice; Troisi, Catherine; Mbwambo, Jessie; Adeboye, Adeniyi; McCurdy, Sheryl

2016-01-01

Studies have shown high rates of depression among men who have sex with men (MSM) in developed countries. Studies have also shown association between depression and HIV risk among MSM. However, very little research has been done on depression among African MSM. We assessed depression and HIV risk among a sample of MSM in Tanzania. We reviewed data on 205 MSM who were recruited from two Tanzanian cities using the respondent driven sampling method. Demographic and behavioral data were collected using a structured questionnaire. HIV and sexually transmitted infections data were determined from biological tests. Depression scores were assessed using the Patient Health Questionnaire (PHQ-9). For the analysis, depression scores were dichotomized as depressed (PHQ > 4) and not depressed (PHQ ≤ 4). Bivariate and multivariable Poisson regression analyses were conducted to assess factors associated with depression. The prevalence of depression in the sample was 46.3%. The mean (±SD) age of the sample was 25 (±5) years. In bivariate analysis, depression was associated with self-identifying as gay (p = .001), being HIV positive (p < .001: <8% of MSM knew they were HIV infected) and having a high number of sexual partners in the last 6 months (p = .001). Depression was also associated with sexual (p = .007), physical (p = .003) and verbal (p < .001) abuse. In the Poisson regression analysis, depression was associated with verbal abuse (APR = 1.91, CI = 1.30-2.81). Depression rates were high among MSM in Tanzania. It is also associated with abuse, HIV and HIV risk behaviors. Thus, reducing the risk of depression may be helpful in reducing the risk of HIV among MSM in Africa. We recommend the colocation of mental health and HIV preventive services as a cost-effective means of addressing both depression and HIV risk among MSM in Africa.

The use and correlates of illicit silicone or “fillers” in a population-based sample of transwomen, San Francisco, 2013

PubMed Central

Wilson, Erin; Rapues, Jenna; Jin, Harry; Raymond, H. Fisher

2014-01-01

Introduction There is a dearth of studies to quantify the use of illicit fillers by transwomen. Case studies of illicit filler injections have pointed to an array of serious health complications, including death. Aim The aim of this study was to determine the population prevalence of filler use among transwomen, and to identify correlations with filler use. Methods An analysis of data collected in 2013 with a population-based sample of 234 transwomen recruited using respondent driven sampling (RDS). We used RDS weights to conduct bivariate and multivariate analyses of correlates of filler use. Main Outcome measures Main outcome measures were an RDS-weighted population prevalence of filler use among transwomen and differences in demographic characteristics, transition-related care factors and self-esteem related to appearance. Results Weighted filler prevalence among transwomen was 16.7%. Being a transwomen between 30–49 years of age, owning/renting or living with a partner/family/friend, having had and planning to have surgery in the future and having used non-prescribed hormones were all associated with filler use. HIV was not associated with filler use. Conclusions This study provides the first known estimate to date of the prevalence of filler use in a population-based sample of transwomen in San Francisco. Accessing illicit fillers may be the only choice available for many transwomen due to the cost of legal surgeries and other procedures to change one’s appearance. An important next step in this research is to determine the overall prevalence and long-term consequences of filler use among transwomen, to explore how the use of fillers is protective to the safety and wellbeing of transwomen, and to find safe and affordable alternatives to this method that meets important gender-related appearance needs. PMID:24810672

Effects of nitrogen enrichment on soil organic matter in tropical forests with different ambient nutrient status

NASA Astrophysics Data System (ADS)

Vaughan, E.; Cusack, D. F.; McDowell, W. H.; Marin-Spiotta, E.

2017-12-01

Nitrogen (N) enrichment is a widespread and increasingly important human influence on ecosystems globally, with implications for net primary production and biogeochemical processes. Previous research has shown that N enrichment can alter soil carbon (C) cycling, although the direction and magnitude of the changes are not consistent across studies, and may change with time. Inconsistent responses to N additions may be due to differences in ambient nutrient status, and/or variable responses of plant C inputs and microbial decomposition. Although plant production in the tropics is not often limited by N, soil processes may respond differently to N enrichment. Our study uses a 15-year N addition experiment at two different tropical forest sites in the Luquillo Long-Term Ecological Research project site in Puerto Rico to address long-term changes in soil C pools due to fertilization. The two forests differ in elevation and ambient nutrient status. Soil sampling three and five years post-fertilization showed increased soil C concentrations under fertilization, driven by increases in mineral-associated C (Cusack et al. 2011). However, the longer-term trends at these sites are unknown. To this end, soil samples were collected following fifteen years of fertilization. Soils were sampled from 0-10 cm and 10-20 cm. Bulk soil C and N concentrations will be measured and compared to samples collected before fertilization (2002) and three years post fertilization (2005). We are using density fractionation to isolate different soil organic matter pools into a free light, occluded light, and dense, mineral associated fraction. These pools represent different mechanisms of soil organic matter stabilization, and provide more detailed insight into changes in bulk soil C. These data will provide insight into the effects of N enrichment on tropical forest soils, and how those effects may change through time with a unique long-term data set.

Patterns of drug dependence in a Queensland (Australia) sample of Indigenous and non-Indigenous people who inject drugs.

PubMed

Smirnov, Andrew; Kemp, Robert; Ward, James; Henderson, Suzanna; Williams, Sidney; Dev, Abhilash; Najman, Jake M

2016-09-01

Despite over-representation of Indigenous Australians in sentinel studies of injecting drug use, little is known about relevant patterns of drug use and dependence. This study compares drug dependence and possible contributing factors in Indigenous and non-Indigenous Australians who inject drugs. Respondent-driven sampling was used in major cities and 'peer recruitment' in regional towns of Queensland to obtain a community sample of Indigenous (n = 282) and non-Indigenous (n = 267) injectors. Data are cross sectional. Multinomial models were developed for each group to examine types of dependence on injected drugs (no dependence, methamphetamine-dependent only, opioid-dependent only, dependent on methamphetamine and opioids). Around one-fifth of Indigenous and non-Indigenous injectors were dependent on both methamphetamine and opioids in the previous 12 months. Psychological distress was associated with dual dependence on these drugs for Indigenous [adjusted relative risk (ARR) 4.86, 95% confidence interval (CI) 2.08-11.34] and non-Indigenous (ARR 4.14, 95% CI 1.59-10.78) participants. Unemployment (ARR 8.98, 95% CI 2.25-35.82) and repeated (> once) incarceration as an adult (ARR 3.78, 95% CI 1.43-9.97) were associated with dual dependence for Indigenous participants only. Indigenous participants had high rates of alcohol dependence, except for those dependent on opioids only. The drug dependence patterns of Indigenous and non-Indigenous people who inject drugs were similar, including the proportions dependent on both methamphetamine and opioids. However, for Indigenous injectors, there was a stronger association between drug dependence and contextual factors such as unemployment and incarceration. Expansion of treatment options and community-level programs may be required. [Smirnov A, Kemp R, Ward J, Henderson S, Williams S, Dev A, Najman J M. Patterns of drug dependence in a Queensland (Australia) sample of Indigenous and non-Indigenous people who inject drugs. Drug Alcohol Rev 2016;35:611-619]. © 2016 Australasian Professional Society on Alcohol and other Drugs.

NHEXAS PHASE I ARIZONA STUDY--PESTICIDES IN DERMAL WIPES ANALYTICAL RESULTS

EPA Science Inventory

The Pesticides in Dermal Wipes data set contains analytical results for measurements of up to 3 pesticides in 177 dermal wipe samples over 177 households. Each sample was collected from the primary respondent within each household during Stage III of the NHEXAS study. The Derma...

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--PESTICIDES IN DERMAL ANALYTICAL RESULTS

EPA Science Inventory

The Pesticides in Dermal Wipes data set contains analytical results for measurements of up to 8 pesticides in 86 dermal wipe samples over 86 households. Each sample was collected from the primary respondent within each household. The Dermal/Pesticide hand wipe was collected 7 d...

NHEXAS PHASE I MARYLAND STUDY--PESTICIDES IN FOOD ANALYTICAL RESULTS

EPA Science Inventory

The Pesticides in Duplicate Diet Food data set contains analytical results for measurements of up to 10 pesticides in 682 food samples over 80 households. Each sample was collected as a duplicate of the food consumed by the primary respondent during a four-day period commencing ...

NHEXAS PHASE I MARYLAND STUDY--METALS IN FOOD ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Duplicate Diet Food data set contains analytical results for measurements of up to 11 metals in 773 food samples over 80 households. Each sample was collected as a duplicate of the food consumed by the primary respondent during a four-day period commencing with the...

NHEXAS PHASE I MARYLAND STUDY--METALS IN URINE ANALYTICAL RESULTS

EPA Science Inventory

The Metals in Urine data set contains analytical results for measurements of up to 3 metals in 376 urine samples over 80 households. Each sample was collected from the primary respondent within each household during the study and represented the first morning void of either Day ...

Multiple-Matrix Sampling: A Technique for Maximizing the Effectiveness of Lengthy Survey Instruments.

ERIC Educational Resources Information Center

Shemick, John M.

1983-01-01

In a project to identify and verify professional competencies for beginning industrial education teachers, researchers found a 173-item questionnaire unwieldy. Using multiple-matrix sampling, they distributed subsets of items to respondents, resulting in adequate returns as well as duplication, postage, and time savings. (SK)

ESTIMATION OF TOTAL DISSOLVED NITRATE LOAD IN NATURAL STREAM FLOWS USING AN IN-STREAM MONITOR

EPA Science Inventory

Estuaries respond rapidly to rain events and the nutrients carried by inflowing rivers such that discrete samples at weekly or monthly intervals are inadequate to catch the maxima and minima in nutrient variability. To acquire data with sufficient sampling frequency to realistica...

Frequency-time coherence for all-optical sampling without optical pulse source

PubMed Central

Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

2016-01-01

Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift. PMID:27687495

Temporal Dynamics of In-Field Bioreactor Populations Reflect the Groundwater System and Respond Predictably to Perturbation.

PubMed

King, Andrew J; Preheim, Sarah P; Bailey, Kathryn L; Robeson, Michael S; Roy Chowdhury, Taniya; Crable, Bryan R; Hurt, Richard A; Mehlhorn, Tonia; Lowe, Kenneth A; Phelps, Tommy J; Palumbo, Anthony V; Brandt, Craig C; Brown, Steven D; Podar, Mircea; Zhang, Ping; Lancaster, W Andrew; Poole, Farris; Watson, David B; W Fields, Matthew; Chandonia, John-Marc; Alm, Eric J; Zhou, Jizhong; Adams, Michael W W; Hazen, Terry C; Arkin, Adam P; Elias, Dwayne A

2017-03-07

Temporal variability complicates testing the influences of environmental variability on microbial community structure and thus function. An in-field bioreactor system was developed to assess oxic versus anoxic manipulations on in situ groundwater communities. Each sample was sequenced (16S SSU rRNA genes, average 10,000 reads), and biogeochemical parameters are monitored by quantifying 53 metals, 12 organic acids, 14 anions, and 3 sugars. Changes in dissolved oxygen (DO), pH, and other variables were similar across bioreactors. Sequencing revealed a complex community that fluctuated in-step with the groundwater community and responded to DO. This also directly influenced the pH, and so the biotic impacts of DO and pH shifts are correlated. A null model demonstrated that bioreactor communities were driven in part not only by experimental conditions but also by stochastic variability and did not accurately capture alterations in diversity during perturbations. We identified two groups of abundant OTUs important to this system; one was abundant in high DO and pH and contained heterotrophs and oxidizers of iron, nitrite, and ammonium, whereas the other was abundant in low DO with the capability to reduce nitrate. In-field bioreactors are a powerful tool for capturing natural microbial community responses to alterations in geochemical factors beyond the bulk phase.

Motivations for Food Consumption during Specific Eating Occasions in Turkey.

PubMed

Chambers, Delores; Phan, Uyen T X; Chanadang, Sirichat; Maughan, Curtis; Sanchez, Karolina; Di Donfrancesco, Brizio; Gomez, David; Higa, Federica; Li, Han; Chambers, Edgar; Esen, Eyyup

2016-05-24

Several studies in different countries have been conducted to investigate factors affecting food choices. The objective of this study was to understand the motivations of specific food and beverage choices for different eating occasions in a typical diet of the Turkish people. A convenience sample of 141 respondents from seven different geographical regions in Turkey completed an online survey questionnaire that included questions about demographic information and details about their latest eating occasion. Respondents reported all of their motivations for choosing each food/beverage item reported for that specific eating occasion. Results indicated that different motivations played different roles in food choices of people in Turkey. Liking was a key characteristic for all eating occasions, but key natural concerns were even more important at breakfast, and need and hunger were more important for a mid-afternoon snack. Lunch involved additional motivations such as Sociability, Variety Seeking, and Social Norms. In addition to Liking, choices of different food groups were also driven by other motivations such as Habits, Convenience, Need and Hunger, Natural Concerns, and Health. This study helped better understand the current dietary patterns of Turkish people as well as the motives underlying their choices of foods and beverages for different meals and snacks. These findings could be useful for dietary campaigns that aim to improve eating behaviors in Turkey.

Dental problems and Familismo: social network discussion of oral health issues among adults of Mexican origin living in the Midwest United States.

PubMed

Maupome, G; McConnell, W R; Perry, B L

2016-12-01

To examine the influence of collectivist orientation (often called familismo when applied to the Latino sub-group in the United States) in oral health discussion networks. Through respondent-driven sampling and face-to-face interviews, we identified respondents' (egos) personal social network members (alters). Egos stated whom they talked with about oral health, and how often they discussed dental problems in the preceding 12 months. An urban community of adult Mexican-American immigrants in the Midwest United States. We interviewed 332 egos (90% born in Mexico); egos named an average of 3.9 alters in their networks, 1,299 in total. We applied egocentric network methods to examine the ego, alter, and network variables that characterize health discussion networks. Kin were most often leveraged when dental problems arose; egos relied on individuals whom they perceive to have better knowledge about dental matters. However, reliance on knowledgeable alters decreased among egos with greater behavioral acculturation. This paper developed a network-based conceptualization of familismo. We describe the structure of oral health networks, including kin, fictive kin, peers, and health professionals, and examine how networks and acculturation help shape oral health among these Mexican-Americans. Copyright© 2016 Dennis Barber Ltd

Syringe Access, Syringe Sharing, and Police Encounters among People Who Inject Drugs in New York City: A Community-Level Perspective

PubMed Central

Beletsky, Leo; Heller, Daliah; Jenness, Samuel M.; Neaigus, Alan; Gelpi-Acosta, Camila; Hagan, Holly

2013-01-01

Background Injection drug user (IDU) experience and perceptions of police practices may alter syringe exchange program (SEP) use or influence risky behaviour. Previously, no community-level data had been collected to identify the prevalence or correlates of police encounters reported by IDUs in the United States. Methods New York City IDUs recruited through respondent-driven sampling were asked about past-year police encounters and risk behaviours, as part of the National HIV Behavioural Surveillance study. Data were analysed using multiple logistic regression. Results A majority (52%) of respondents (n=514) reported being stopped by police officers; 10% reported syringe confiscation. In multivariate modelling, IDUs reporting police stops were less likely to use SEPs consistently (adjusted odds ratio [AOR]=0.59; 95% confidence interval [CI]=0.40–0.89), and IDUs who had syringes confiscated may have been more likely to share syringes (AOR=1.76; 95% CI=0.90–3.44), though the finding did not reach statistical significance. Conclusions Findings suggest that police encounters may influence consistent SEP use. The frequency of IDU-police encounters highlights the importance of including contextual and structural measures in infectious disease risk surveillance, and the need to develop approaches harmonizing structural policing and public health. PMID:23916801

The Associations of Perceived Social Support with Key HIV Risk and Protective Factors Among Young Males Who Have Sex with Males in Bangkok and Chiang Mai, Thailand.

PubMed

Johnston, Lisa; Steinhaus, Mara; Sass, Justine; Benjarattanaporn, Patchara; Sirinirund, Petchsri; Siraprapasiri, Taweesap; Gass, Robert

2018-06-01

This study used respondent-driven sampling to explore the effects of social support on HIV risk and protective factors among young males who have sex with males (YMSM) in Bangkok (N = 273) and Chiang Mai (N = 243), Thailand. It compared different measures of social support, including living situation, the proportion of family and friends to whom the respondent had disclosed their same-sex attraction, and scores on the multi-dimensional scale of perceived social support as predictors of two outcomes of interest-coerced first sex and HIV knowledge. Social support from family played a mediating role in both outcomes among YMSM in Bangkok but not those from Chiang Mai. Though social support from friends was also studied, it was less strongly associated with the outcomes of interest. The findings support interventions designed to leverage social support networks to increase HIV knowledge and decrease coerced first sex among YMSM. At the same time, they demonstrate that there is not a single risk or demographic profile encompassing all YMSM. Successful programs and policies will need to consider the specific attributes and social environment of YMSM in particular locations in order to effectively address HIV risks.

Temporal Dynamics of In-Field Bioreactor Populations Reflect the Groundwater System and Respond Predictably to Perturbation

DOE PAGES

King, Andrew J.; Preheim, Sarah P.; Bailey, Kathryn L.; ...

2017-01-23

Temporal variability complicates testing the influences of environmental variability on microbial community structure and thus function. An in-field bioreactor system was developed to assess oxic versus anoxic manipulations on in-situ groundwater communities. Each sample was sequenced (16S SSU rRNA genes, average 10,000 reads) and biogeochemical parameters monitored by quantifying 53 metals, 12 organic acids, 14 anions and 3 sugars. Changes in dissolved oxygen (DO), pH, and other variables were similar across bioreactors. Sequencing revealed a complex community that fluctuated in-step with the groundwater community, and responded to DO. This also directly influenced the pH and so the biotic impacts ofmore » DO and pH shifts are correlated. A null model demonstrated that bioreactor communities were driven in part by experimental conditions but also by stochastic variability and did not accurately capture alterations in diversity during perturbations. We identified two groups of abundant OTUs important to this system; one was abundant in high DO and pH and contained heterotrophs and oxidizers of iron, nitrite, and ammonium, whereas the other was abundant in low DO with the capability to reduce nitrate. In-field bioreactors are a powerful tool for capturing natural microbial community responses to alterations in geochemical factors beyond the bulk phase.« less

Temporal Dynamics of In-Field Bioreactor Populations Reflect the Groundwater System and Respond Predictably to Perturbation

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

King, Andrew J.; Preheim, Sarah P.; Bailey, Kathryn L.

Temporal variability complicates testing the influences of environmental variability on microbial community structure and thus function. An in-field bioreactor system was developed to assess oxic versus anoxic manipulations on in-situ groundwater communities. Each sample was sequenced (16S SSU rRNA genes, average 10,000 reads) and biogeochemical parameters monitored by quantifying 53 metals, 12 organic acids, 14 anions and 3 sugars. Changes in dissolved oxygen (DO), pH, and other variables were similar across bioreactors. Sequencing revealed a complex community that fluctuated in-step with the groundwater community, and responded to DO. This also directly influenced the pH and so the biotic impacts ofmore » DO and pH shifts are correlated. A null model demonstrated that bioreactor communities were driven in part by experimental conditions but also by stochastic variability and did not accurately capture alterations in diversity during perturbations. We identified two groups of abundant OTUs important to this system; one was abundant in high DO and pH and contained heterotrophs and oxidizers of iron, nitrite, and ammonium, whereas the other was abundant in low DO with the capability to reduce nitrate. In-field bioreactors are a powerful tool for capturing natural microbial community responses to alterations in geochemical factors beyond the bulk phase.« less

Assessing the health attitudes, beliefs, and behaviors of African Americans attending church: a comparison from two communities.

PubMed

Lewis, R K; Green, B L

2000-06-01

Public health officials and researchers continue to be increasingly concerned about the health of populations of color, especially African Americans. A survey was administered in African American churches in two communities (Wichita, KS and Tuscaloosa, AL) to gather information concerning health behaviors and beliefs and to design interventions that might improve their health status. The study examined the homogeneity of attitudes, beliefs, and behaviors across these samples and to determine the readiness to change using the Transtheoritical Model. Individuals completed a 33-item survey: 6 demographic questions, 12 health behavior questions, 8 health belief questions, 3 church attendance questions, and 4 church-based health promotion program questions. The total sample consisted of 429 respondents. The results showed that 93% of respondents have had their blood pressure checked in the past 2 years. While only 44% indicated eating a high fiber diet during the week. Thirty percent of respondents indicated that their health was dependent on fate or destiny. The findings from this study confirm that among both samples that health attitudes, beliefs, and behaviors need to be changed to lower the risk of certain diseases and disorders. The findings also indicate that both samples have similar beliefs about health that may have important implications for disseminating information to the community. Innovative and culturally sensitive programs are needed in the African American community if disparities in health are to diminish.

The Study on Mental Health at Work: Design and sampling.

PubMed

Rose, Uwe; Schiel, Stefan; Schröder, Helmut; Kleudgen, Martin; Tophoven, Silke; Rauch, Angela; Freude, Gabriele; Müller, Grit

2017-08-01

The Study on Mental Health at Work (S-MGA) generates the first nationwide representative survey enabling the exploration of the relationship between working conditions, mental health and functioning. This paper describes the study design, sampling procedures and data collection, and presents a summary of the sample characteristics. S-MGA is a representative study of German employees aged 31-60 years subject to social security contributions. The sample was drawn from the employment register based on a two-stage cluster sampling procedure. Firstly, 206 municipalities were randomly selected from a pool of 12,227 municipalities in Germany. Secondly, 13,590 addresses were drawn from the selected municipalities for the purpose of conducting 4500 face-to-face interviews. The questionnaire covers psychosocial working and employment conditions, measures of mental health, work ability and functioning. Data from personal interviews were combined with employment histories from register data. Descriptive statistics of socio-demographic characteristics and logistic regressions analyses were used for comparing population, gross sample and respondents. In total, 4511 face-to-face interviews were conducted. A test for sampling bias revealed that individuals in older cohorts participated more often, while individuals with an unknown educational level, residing in major cities or with a non-German ethnic background were slightly underrepresented. There is no indication of major deviations in characteristics between the basic population and the sample of respondents. Hence, S-MGA provides representative data for research on work and health, designed as a cohort study with plans to rerun the survey 5 years after the first assessment.

Analysis of TLR7, SOCS1 and ISG15 immune genes expression in the peripheral blood of responder and non-responder patients with chronic Hepatitis C

PubMed Central

Dowran, Razieh; Sarvari, Jamal; Moattari, Afagh; Fattahi, Mohammad-Reza; Ramezani, Amin; Hosseini, Seyed Younes

2017-01-01

Aim: To evaluate the baseline expression of the immune genes in PBMCs of responder and non-responder patients with chronic Hepatitis C. Background: Although the contribution of peripheral blood mononuclear cell (PBMC) gene expression in treatment outcome of hepatitis C virus (HCV) infection is supposed, it has remained to be distinctly delineated. The baseline expression of the immune genes inside PBMCs may reflect the responsiveness status following IFN treatment. Methods: Totally, 22 chronic HCV encompasses 10 responders and 12 non-responsive cases enrolled randomly regarding medical records. The PBMCs from the peripheral blood samples were isolated and then incubated for 6 hours in the culture media. The baseline expression of TLR7, SOCS1 and ISG15 was measured by Real time PCR. Results: The gene expression pattern in PBMCs of both groups showed a similar trend. The expression of SOCS1 and TLR7 genes showed higher levels in non-responder group (P>0.05). The result of ISG15 showed a higher but non-significant expression in the responder group (P>0.05). Conclusion: The similar pattern of TLR7, SOCS1 and ISG15 expression in the responder and non-responder patients indicated their poor discriminating and predictive value in PBMCs sample. PMID:29379591

Climatically driven loss of calcium in steppe soil as a sink for atmospheric carbon

Treesearch

A.G. Lapenis; G.B. Lawrence; S.W. Bailey; B.F. Aparin; A.I. Shiklomanov; N.A. Speranskaya; M.S. Torn; M. Calef

2008-01-01

During the last several thousand years the semi-arid, cold climate of the Russian steppe formed highly fertile soils rich in organic carbon and calcium (classified as Chernozems in the Russian system). Analysis of archived soil samples collected in Kemannaya Steppe Preserve in 1920, 1947, 1970, and fresh samples collected in 1998 indicated that the native steppe...

Capillary electrophoresis: Imaging of electroosmotic and pressure driven flow profiles in fused silica capillaries

NASA Technical Reports Server (NTRS)

Williams, George O., Jr.

1996-01-01

This study is a continuation of the summer of 1994 NASA/ASEE Summer Faculty Fellowship Program. This effort is a portion of the ongoing work by the Biophysics Branch of the Marshall Space Flight Center. The work has focused recently on the separation of macromolecules using capillary electrophoresis (CE). Two primary goals were established for the effort this summer. First, we wanted to use capillary electrophoresis to study the electrohydrodynamics of a sample stream. Secondly, there was a need to develop a methodology for using CE for separation of DNA molecules of various sizes. In order to achieve these goals we needed to establish a procedure for detection of a sample plug under the influence of an electric field Detection of the sample with the microscope and image analysis system would be helpful in studying the electrohydrodynamics of this stream under load. Videotaping this process under the influence of an electric field in real time would also be useful. Imaging and photography of the sample/background electrolyte interface would be vital to this study. Finally, detection and imaging of electroosmotic flow and pressure driven flow must be accomplished.

454 pyrosequencing analysis on faecal samples from a randomized DBPC trial of colicky infants treated with Lactobacillus reuteri DSM 17938.

PubMed

Roos, Stefan; Dicksved, Johan; Tarasco, Valentina; Locatelli, Emanuela; Ricceri, Fulvio; Grandin, Ulf; Savino, Francesco

2013-01-01

To analyze the global microbial composition, using large-scale DNA sequencing of 16 S rRNA genes, in faecal samples from colicky infants given L. reuteri DSM 17938 or placebo. Twenty-nine colicky infants (age 10-60 days) were enrolled and randomly assigned to receive either Lactobacillus reuteri (10(8) cfu) or a placebo once daily for 21 days. Responders were defined as subjects with a decrease of 50% in daily crying time at day 21 compared with the starting point. The microbiota of faecal samples from day 1 and 21 were analyzed using 454 pyrosequencing. The primers: Bakt_341F and Bakt_805R, complemented with 454 adapters and sample specific barcodes were used for PCR amplification of the 16 S rRNA genes. The structure of the data was explored by using permutational multivariate analysis of variance and effects of different variables were visualized with ordination analysis. The infants' faecal microbiota were composed of Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes as the four main phyla. The composition of the microbiota in infants with colic had very high inter-individual variability with Firmicutes/Bacteroidetes ratios varying from 4000 to 0.025. On an individual basis, the microbiota was, however, relatively stable over time. Treatment with L. reuteri DSM 17938 did not change the global composition of the microbiota, but when comparing responders with non-responders the group responders had an increased relative abundance of the phyla Bacteroidetes and genus Bacteroides at day 21 compared with day 0. Furthermore, the phyla composition of the infants at day 21 could be divided into three enterotype groups, dominated by Firmicutes, Bacteroidetes, and Actinobacteria, respectively. L. reuteri DSM 17938 did not affect the global composition of the microbiota. However, the increase of Bacteroidetes in the responder infants indicated that a decrease in colicky symptoms was linked to changes of the microbiota. ClinicalTrials.gov NCT00893711.

Fair Shares and Sharing Fairly: A Survey of Public Views on Open Science, Informed Consent and Participatory Research in Biobanking

PubMed Central

Joly, Yann; Dalpé, Gratien; So, Derek; Birko, Stanislav

2015-01-01

Context Biobanks are important resources which enable large-scale genomic research with human samples and data, raising significant ethical concerns about how participants’ information is managed and shared. Three previous studies of the Canadian public’s opinion about these topics have been conducted. Building on those results, an online survey representing the first study of public perceptions about biobanking spanning all Canadian provinces was conducted. Specifically, this study examined qualitative views about biobank objectives, governance structure, control and ownership of samples and data, benefit sharing, consent practices and data sharing norms, as well as additional questions and ethical concerns expressed by the public. Results Over half the respondents preferred to give a one-time general consent for the future sharing of their samples among researchers. Most expressed willingness for their data to be shared with the international scientific community rather than used by one or more Canadian institutions. Whereas more respondents indicated a preference for one-time general consent than any other model of consent, they constituted less than half of the total responses, revealing a lack of consensus among survey respondents regarding this question. Respondents identified biobank objectives, governance structure and accountability as the most important information to provide participants. Respondents’ concerns about biobanking generally centred around the control and ownership of biological samples and data, especially with respect to potential misuse by insurers, the government and other third parties. Although almost half the respondents suggested that these should be managed by the researchers’ institutions, results indicate that the public is interested in being well-informed about these projects and suggest the importance of increased involvement from participants. In conclusion, the study discusses the viability of several proposed models for informed consent, including e-governance, independent trustees and the use of exclusion clauses, in the context of these new findings about the views of the Canadian public. PMID:26154134

Sexual Violence against Men Who Have Sex with Men and Transgender Women in Mongolia: A Mixed-Methods Study of Scope and Consequences.

PubMed

Peitzmeier, Sarah M; Yasin, Faiza; Stephenson, Rob; Wirtz, Andrea L; Delegchoimbol, Altanchimeg; Dorjgotov, Myagmardorj; Baral, Stefan

2015-01-01

The role of sexual violence in health and human rights-related outcomes, including HIV, is receiving increasing attention globally, yet the prevalence, patterns, and correlates of sexual violence have been little-studied among men who have sex with men (MSM) and transgender women in low and middle income countries. A mixed-methods study with quantitative and qualitative phases was conducted among MSM and transgender women in Ulaanbaatar, Mongolia. Methods included respondent-driven sampling (RDS) with structured socio-behavioral surveys (N = 313) as well as qualitative methods including 30 in-depth interviews and 2 focus group discussions. Forced sex in the last three years was reported by 14.7% of respondents (RDS-weighted estimate, 95%CI: 9.4-20.1; crude estimate 16.1%, 49/307) in the quantitative phase. A descriptive typology of common scenarios was constructed based on the specific incidents of sexual violence shared by respondents in the qualitative phase (37 incidents across 28 interviews and 2 focus groups). Eight major types of sexual violence were identified, most frequent of which were bias-motivated street violence and alcohol-involved party-related violence. Many vulnerabilities to and consequences of sexual violence described during the qualitative phase were also independently associated with forced sex, including alcohol use at least once per week (AOR = 3.39, 95% CI:1.69-6.81), and having received payment for sex (AOR = 2.77, 95% CI:1.14-6.75). Building on the promising strategies used in other settings to prevent and respond to sexual violence, similar strengthening of legal and social sector responses may provide much needed support to survivors and prevent future sexual violence.

Sexual Violence against Men Who Have Sex with Men and Transgender Women in Mongolia: A Mixed-Methods Study of Scope and Consequences

PubMed Central

Peitzmeier, Sarah M.; Yasin, Faiza; Stephenson, Rob; Wirtz, Andrea L.; Delegchoimbol, Altanchimeg; Dorjgotov, Myagmardorj; Baral, Stefan

2015-01-01

The role of sexual violence in health and human rights-related outcomes, including HIV, is receiving increasing attention globally, yet the prevalence, patterns, and correlates of sexual violence have been little-studied among men who have sex with men (MSM) and transgender women in low and middle income countries. A mixed-methods study with quantitative and qualitative phases was conducted among MSM and transgender women in Ulaanbaatar, Mongolia. Methods included respondent-driven sampling (RDS) with structured socio-behavioral surveys (N = 313) as well as qualitative methods including 30 in-depth interviews and 2 focus group discussions. Forced sex in the last three years was reported by 14.7% of respondents (RDS-weighted estimate, 95%CI: 9.4–20.1; crude estimate 16.1%, 49/307) in the quantitative phase. A descriptive typology of common scenarios was constructed based on the specific incidents of sexual violence shared by respondents in the qualitative phase (37 incidents across 28 interviews and 2 focus groups). Eight major types of sexual violence were identified, most frequent of which were bias-motivated street violence and alcohol-involved party-related violence. Many vulnerabilities to and consequences of sexual violence described during the qualitative phase were also independently associated with forced sex, including alcohol use at least once per week (AOR = 3.39, 95% CI:1.69–6.81), and having received payment for sex (AOR = 2.77, 95% CI:1.14–6.75). Building on the promising strategies used in other settings to prevent and respond to sexual violence, similar strengthening of legal and social sector responses may provide much needed support to survivors and prevent future sexual violence. PMID:26431311

Genetic polymorphisms in MDR1, CYP3A4 and CYP3A5 genes in a Ghanaian population: a plausible explanation for altered metabolism of ivermectin in humans?

PubMed Central

2010-01-01

Background Ivermectin, a substrate of multidrug resistance (MDR1) gene and cytochrome P450 (CYP) 3A4, has been used successfully in the treatment of onchocerciasis in Ghana. However, there have been reports of suboptimal response in some patients after repeated treatment. Polymorphisms in host MDR1 and CYP3A genes may explain the observed suboptimal response to ivermectin. We genotyped relevant functional polymorphisms of MDR1 and CYP3A in a random sample of healthy Ghanaians and compared the data with that of ivermectin-treated patients with a view to exploring the relationship between suboptimal response to ivermectin and MDR1 and CYP3A allelic frequencies. Methods Using PCR-RFLP, relevant polymorphic alleles of MDR1 and CYP3A4 genes were analysed in 204 randomly selected individuals and in 42 ivermectin treated patients. Results We recorded significantly higher MDR1 (3435T) variant allele frequency in suboptimal responders (21%) than in patients who responded to treatment (12%) or the random population sample (11%). CYP3A4*1B, CYP3A5*3 and CYP3A5*6 alleles were detected at varied frequencies for the sampled Ghanaian population, responders and suboptimal responders to ivermectin. CYP3A5*1/CYP3A5*1 and CYP3A5*1/CYP3A5*3 genotypes were also found to be significantly different for responders and suboptimal responders. Haplotype (*1/*1/*3/*1) was determined to be significantly different between responders and suboptimal responders indicating a possible role of these haplotypes in treatment response with ivermectin. Conclusion A profile of pharmacogenetically relevant variants for MDR1, CYP3A4 and CYP3A5 genes has been generated for a random population of 204 Ghanaians to address the scarcity of data within indigenous African populations. In 42 patients treated with ivermectin, difference in MDR1 variant allele frequency was observed between suboptimal responders and responders. PMID:20630055

Genetic polymorphisms in MDR1, CYP3A4 and CYP3A5 genes in a Ghanaian population: a plausible explanation for altered metabolism of ivermectin in humans?

PubMed

Kudzi, William; Dodoo, Alexander N O; Mills, Jeremy J

2010-07-14

Ivermectin, a substrate of multidrug resistance (MDR1) gene and cytochrome P450 (CYP) 3A4, has been used successfully in the treatment of onchocerciasis in Ghana. However, there have been reports of suboptimal response in some patients after repeated treatment. Polymorphisms in host MDR1 and CYP3A genes may explain the observed suboptimal response to ivermectin. We genotyped relevant functional polymorphisms of MDR1 and CYP3A in a random sample of healthy Ghanaians and compared the data with that of ivermectin-treated patients with a view to exploring the relationship between suboptimal response to ivermectin and MDR1 and CYP3A allelic frequencies. Using PCR-RFLP, relevant polymorphic alleles of MDR1 and CYP3A4 genes were analysed in 204 randomly selected individuals and in 42 ivermectin treated patients. We recorded significantly higher MDR1 (3435T) variant allele frequency in suboptimal responders (21%) than in patients who responded to treatment (12%) or the random population sample (11%). CYP3A4*1B, CYP3A5*3 and CYP3A5*6 alleles were detected at varied frequencies for the sampled Ghanaian population, responders and suboptimal responders to ivermectin. CYP3A5*1/CYP3A5*1 and CYP3A5*1/CYP3A5*3 genotypes were also found to be significantly different for responders and suboptimal responders. Haplotype (*1/*1/*3/*1) was determined to be significantly different between responders and suboptimal responders indicating a possible role of these haplotypes in treatment response with ivermectin. A profile of pharmacogenetically relevant variants for MDR1, CYP3A4 and CYP3A5 genes has been generated for a random population of 204 Ghanaians to address the scarcity of data within indigenous African populations. In 42 patients treated with ivermectin, difference in MDR1 variant allele frequency was observed between suboptimal responders and responders.

Men at risk; a qualitative study on HIV risk, gender identity and violence among men who have sex with men who report high risk behavior in Kampala, Uganda.

PubMed

King, Rachel; Barker, Joseph; Nakayiwa, Sylvia; Katuntu, David; Lubwama, George; Bagenda, Danstan; Lane, Tim; Opio, Alex; Hladik, Wolfgang

2013-01-01

In Uganda, men who have sex with men (MSM) are at high risk for HIV. Between May 2008 and February 2009 in Kampala, Uganda, we used respondent driven sampling (RDS) to recruit 295 MSM≥18 years who reported having had sex with another man in the preceding three months. The parent study conducted HIV and STI testing and collected demographic and HIV-related behavioral data through audio computer-assisted self-administered interviews. We conducted a nested qualitative sub-study with 16 men purposively sampled from among the survey participants based on responses to behavioral variables indicating higher risk for HIV infection. Sub-study participants were interviewed face-to-face. Domains of inquiry included sexual orientation, gender identity, condom use, stigma, discrimination, violence and health seeking behavior. Emergent themes included a description of sexual orientation/gender identity categories. All groups of men described conflicting feelings related to their sexual orientation and contextual issues that do not accept same-sex identities or behaviors and non-normative gender presentation. The emerging domains for facilitating condom use included: lack of trust in partner and fear of HIV infection. We discuss themes in the context of social and policy issues surrounding homosexuality and HIV prevention in Uganda that directly affect men's lives, risk and health-promoting behaviors.

Men at Risk; a Qualitative Study on HIV Risk, Gender Identity and Violence among Men Who Have Sex with Men Who Report High Risk Behavior in Kampala, Uganda

PubMed Central

King, Rachel; Barker, Joseph; Nakayiwa, Sylvia; Katuntu, David; Lubwama, George; Bagenda, Danstan; Lane, Tim; Opio, Alex; Hladik, Wolfgang

2013-01-01

In Uganda, men who have sex with men (MSM) are at high risk for HIV. Between May 2008 and February 2009 in Kampala, Uganda, we used respondent driven sampling (RDS) to recruit 295 MSM≥18 years who reported having had sex with another man in the preceding three months. The parent study conducted HIV and STI testing and collected demographic and HIV-related behavioral data through audio computer-assisted self-administered interviews. We conducted a nested qualitative sub-study with 16 men purposively sampled from among the survey participants based on responses to behavioral variables indicating higher risk for HIV infection. Sub-study participants were interviewed face-to-face. Domains of inquiry included sexual orientation, gender identity, condom use, stigma, discrimination, violence and health seeking behavior. Emergent themes included a description of sexual orientation/gender identity categories. All groups of men described conflicting feelings related to their sexual orientation and contextual issues that do not accept same-sex identities or behaviors and non-normative gender presentation. The emerging domains for facilitating condom use included: lack of trust in partner and fear of HIV infection. We discuss themes in the context of social and policy issues surrounding homosexuality and HIV prevention in Uganda that directly affect men's lives, risk and health-promoting behaviors. PMID:24358239

Traffic risk behaviors at nightlife: drinking, taking drugs, driving, and use of public transport by young people.

PubMed

Calafat, A; Blay, N; Juan, M; Adrover, D; Bellis, M A; Hughes, K; Stocco, P; Siamou, I; Mendes, F; Bohrn, K

2009-04-01

Road traffic crashes associated with nightlife alcohol and recreational drug use are a major health problem for young people. This study explores use of different forms of transport to and from nightlife environments and the relationships between traffic risk behaviors, drunkenness, and drug consumption. 1363 regular nightlife users from nine European cities in 2006 completed a self-administered and anonymous questionnaire. Sampling utilized a variation of respondent-driven sampling. Private car was the most frequent form of transport used when going out, especially by males and older individuals. Drug use was related to crashes and traffic risk behaviors, including having a lift from someone drunk or driving drunk or driving having taken drugs; drunkenness was related to risk behaviors but not to crashes (possibly because drunk people tend to use the private car less). Males showed higher levels of drunkenness and drug consumption, traffic risk behaviors, and traffic crashes. Age is not related to the traffic risk behaviors, but older individuals had less crashes. There are serious health problems related to transport and recreational nightlife activities. It is necessary to improve later public transport services, complemented by actions that deter the use of private cars. The relationships of both drunkenness and cannabis/cocaine use with traffic risk behaviors should be addressed and programs implemented to change risk perceptions on the effects of illegal drugs on driving.

Associations between injection risk and community disadvantage among suburban injection drug users in southwestern Connecticut, USA.

PubMed

Heimer, Robert; Barbour, Russell; Palacios, Wilson R; Nichols, Lisa G; Grau, Lauretta E

2014-03-01

Increases in drug abuse, injection, and opioid overdoses in suburban communities led us to study injectors residing in suburban communities in southwestern Connecticut, US. We sought to understand the influence of residence on risk and injection-associated diseases. Injectors were recruited by respondent-driven sampling and interviewed about sociodemographics, somatic and mental health, injection risk, and interactions with healthcare, harm reduction, substance abuse treatment, and criminal justice systems. HIV, hepatitis B and C (HBV and HCV) serological testing was also conducted. Our sample was consistent in geographic distribution and age to the general population and to the patterns of heroin-associated overdose deaths in the suburban towns. High rates of interaction with drug abuse treatment and criminal justice systems contrasted with scant use of harm reduction services. The only factors associated with both dependent variables-residence in less disadvantaged census tracts and more injection risk-were younger age and injecting in one's own residence. This contrasts with the common association among urban injectors of injection-associated risk behaviors and residence in disadvantaged communities. Poor social support and moderate/severe depression were associated with risky injection practices (but not residence in specific classes of census tracts), suggesting that a region-wide dual diagnosis approach to the expansion of harm reduction services could be effective at reducing the negative consequences of injection drug use.

Signal enhancement for the sensitivity-limited solid state NMR experiments using a continuous, non-uniform acquisition scheme

NASA Astrophysics Data System (ADS)

Qiang, Wei

2011-12-01

We describe a sampling scheme for the two-dimensional (2D) solid state NMR experiments, which can be readily applied to the sensitivity-limited samples. The sampling scheme utilizes continuous, non-uniform sampling profile for the indirect dimension, i.e. the acquisition number decreases as a function of the evolution time ( t1) in the indirect dimension. For a beta amyloid (Aβ) fibril sample, we observed overall 40-50% signal enhancement by measuring the cross peak volume, while the cross peak linewidths remained comparable to the linewidths obtained by regular sampling and processing strategies. Both the linear and Gaussian decay functions for the acquisition numbers result in similar percentage of increment in signal. In addition, we demonstrated that this sampling approach can be applied with different dipolar recoupling approaches such as radiofrequency assisted diffusion (RAD) and finite-pulse radio-frequency-driven recoupling (fpRFDR). This sampling scheme is especially suitable for the sensitivity-limited samples which require long signal averaging for each t1 point, for instance the biological membrane proteins where only a small fraction of the sample is isotopically labeled.

Demographic and Psychological Predictors of Panel Attrition: Evidence from the New Zealand Attitudes and Values Study

PubMed Central

Satherley, Nicole; Milojev, Petar; Greaves, Lara M.; Huang, Yanshu; Osborne, Danny; Bulbulia, Joseph; Sibley, Chris G.

2015-01-01

This study examines attrition rates over the first four years of the New Zealand Attitudes and Values Study, a longitudinal national panel sample of New Zealand adults. We report the base rate and covariates for the following four distinct classes of respondents: explicit withdrawals, lost respondents, intermittent respondents and constant respondents. A multinomial logistic regression examined an extensive range of demographic and socio-psychological covariates (among them the Big-Six personality traits) associated with membership in these classes (N = 5,814). Results indicated that men, Māori and Asian peoples were less likely to be constant respondents. Conscientiousness and Honesty-Humility were also positively associated with membership in the constant respondent class. Notably, the effect sizes for the socio-psychological covariates of panel attrition tended to match or exceed those of standard demographic covariates. This investigation broadens the focus of research on panel attrition beyond demographics by including a comprehensive set of socio-psychological covariates. Our findings show that core psychological covariates convey important information about panel attrition, and are practically important to the management of longitudinal panel samples like the New Zealand Attitudes and Values Study. PMID:25793746

Blood-Based Analyses of Cancer: Circulating Tumor Cells and Circulating Tumor DNA

PubMed Central

Haber, Daniel A.; Velculescu, Victor E.

2015-01-01

The ability to study nonhematologic cancers through noninvasive sampling of blood is one of the most exciting and rapidly advancing fields in cancer diagnostics. This has been driven both by major technologic advances, including the isolation of intact cancer cells and the analysis of cancer cell–derived DNA from blood samples, and by the increasing application of molecularly driven therapeutics, which rely on such accurate and timely measurements of critical biomarkers. Moreover, the dramatic efficacy of these potent cancer therapies drives the selection for additional genetic changes as tumors acquire drug resistance, necessitating repeated sampling of cancer cells to adjust therapy in response to tumor evolution. Together, these advanced noninvasive diagnostic capabilities and their applications in guiding precision cancer therapies are poised to change the ways in which we select and monitor cancer treatments. Significance Recent advances in technologies to analyze circulating tumor cells and circulating tumor DNA are setting the stage for real-time, noninvasive monitoring of cancer and providing novel insights into cancer evolution, invasion, and metastasis. PMID:24801577

Installation of water and gas-sampling wells in low-level radioactive-waste burial trenches, West Valley, New York

USGS Publications Warehouse

Prudic, David E.

1978-01-01

A low-level radioactive-waste burial site, West Valley, N.Y., operated from 1963 to 1975, contains 12 refuse-filled trenches about 20 feet deep in till. Twenty-eight wells, 1.25 inch in diameter, were driven to selected depths in 11 of the 12 trenches to obtain gas and water samples for chemical and radiochemical analysis, water-level measurements for evaluation of trench-cover permeability. Gas from unsaturated refuse above the trench water level was detected in nearly all wells. Rapid water-level response in most wells to pumping of water from trench sumps 20 to 275 feet distant showed the refuse to be highly permeable. Described in detail are the methods and equipment used to (1) install the wells, (2) collect gas and water samples, and (3) monitor radiation and methane concentrations while driving wells into trenches. A record of each well driven into the burial trenches is included. (Woodard-USGS)

Visualization of electrochemically driven solid-state phase transformations using operando hard X-ray spectro-imaging

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

Li, Linsen; Chen-Wiegart, Yu-chen Karen; Wang, Jiajun

In situ techniques with high temporal, spatial and chemical resolution are key to understand ubiquitous solid-state phase transformations, which are crucial to many technological applications. Hard X-ray spectro-imaging can visualize electrochemically driven phase transformations but demands considerably large samples with strong absorption signal so far. Here we show a conceptually new data analysis method to enable operando visualization of mechanistically relevant weakly absorbing samples at the nanoscale and study electrochemical reaction dynamics of iron fluoride, a promising high-capacity conversion cathode material. In two specially designed samples with distinctive microstructure and porosity, we observe homogeneous phase transformations during both discharge andmore » charge, faster and more complete Li-storage occurring in porous polycrystalline iron fluoride, and further, incomplete charge reaction following a pathway different from conventional belief. In conclusion, these mechanistic insights provide guidelines for designing better conversion cathode materials to realize the promise of high-capacity lithium-ion batteries.« less

Visualization of electrochemically driven solid-state phase transformations using operando hard X-ray spectro-imaging

DOE PAGES

Li, Linsen; Chen-Wiegart, Yu-chen Karen; Wang, Jiajun; ...

2015-04-20

In situ techniques with high temporal, spatial and chemical resolution are key to understand ubiquitous solid-state phase transformations, which are crucial to many technological applications. Hard X-ray spectro-imaging can visualize electrochemically driven phase transformations but demands considerably large samples with strong absorption signal so far. Here we show a conceptually new data analysis method to enable operando visualization of mechanistically relevant weakly absorbing samples at the nanoscale and study electrochemical reaction dynamics of iron fluoride, a promising high-capacity conversion cathode material. In two specially designed samples with distinctive microstructure and porosity, we observe homogeneous phase transformations during both discharge andmore » charge, faster and more complete Li-storage occurring in porous polycrystalline iron fluoride, and further, incomplete charge reaction following a pathway different from conventional belief. In conclusion, these mechanistic insights provide guidelines for designing better conversion cathode materials to realize the promise of high-capacity lithium-ion batteries.« less

Highly efficient and ultra-small volume separation by pressure-driven liquid chromatography in extended nanochannels.

PubMed

Ishibashi, Ryo; Mawatari, Kazuma; Kitamori, Takehiko

2012-04-23

The rapidly developing interest in nanofluidic analysis, which is used to examine liquids ranging in amounts from the attoliter to the femtoliter scale, correlates with the recent interest in decreased sample amounts, such as in the field of single-cell analysis. For general nanofluidic analysis, the fact that a pressure-driven flow does not limit the choice of solvents (aqueous or organic) is important. This study shows the first pressure-driven liquid chromatography technique that enables separation of atto- to femtoliter sample volumes, with a high separation efficiency within a few seconds. The apparent diffusion coefficient measurement of the unretentive sample suggests that there is no increase in the viscosity of toluene in the extended nanospace, unlike in aqueous solvents. Evaluation of the normal phase separation, therefore, should involve only the examination of the effect of the small size of the extended nanospace. Compared to a conventionally packed high-performance liquid chromatography column, the separation here results in a faster separation (4 s) by 2 orders of magnitude, a smaller injection volume (10(0) fL) by 9 orders, and a higher separation efficiency (440,000 plates/m) by 1 order. Moreover, the separation behavior agrees with the theory showing that this high efficiency was due to the small and controlled size of the separation channel, where the diffusion through the channel depth direction is fast enough to be neglected. Our chip-based platform should allow direct and real-time analysis or screening of ultralow volume of sample. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Adaptation of the Distance Driven Projection Method for Single Pinhole Collimators in SPECT Imaging

NASA Astrophysics Data System (ADS)

Ihsani, Alvin; Farncombe, Troy

2016-02-01

The modelling of the projection operator in tomographic imaging is of critical importance especially when working with algebraic methods of image reconstruction. This paper proposes a distance-driven projection method which is targeted to single-pinhole single-photon emission computed tomograghy (SPECT) imaging since it accounts for the finite size of the pinhole, and the possible tilting of the detector surface in addition to other collimator-specific factors such as geometric sensitivity. The accuracy and execution time of the proposed method is evaluated by comparing to a ray-driven approach where the pinhole is sub-sampled with various sampling schemes. A point-source phantom whose projections were generated using OpenGATE was first used to compare the resolution of reconstructed images with each method using the full width at half maximum (FWHM). Furthermore, a high-activity Mini Deluxe Phantom (Data Spectrum Corp., Durham, NC, USA) SPECT resolution phantom was scanned using a Gamma Medica X-SPECT system and the signal-to-noise ratio (SNR) and structural similarity of reconstructed images was compared at various projection counts. Based on the reconstructed point-source phantom, the proposed distance-driven approach results in a lower FWHM than the ray-driven approach even when using a smaller detector resolution. Furthermore, based on the Mini Deluxe Phantom, it is shown that the distance-driven approach has consistently higher SNR and structural similarity compared to the ray-driven approach as the counts in measured projections deteriorates.

Symptoms of acute stress in Jewish and Arab Israeli citizens during the Second Lebanon War.

PubMed

Yahav, Rivka; Cohen, Miri

2007-10-01

The "Second Lebanon War" exposed northern Israel to massive missile attacks, aimed at civilian centers, Jewish and Arab, for a period of several weeks. To assess prevalence of acute stress disorder (ASD) and acute stress symptoms (ASS) in Jewish and Arab samples, and their correlates with demographic and exposure variables. Telephone survey conducted in the third week of the second Lebanon war with a random sample of 133 Jewish and 66 Arab adult residents of northern Israel. ASD, ASS and symptoms-related impairment were measured by the Acute Stress Disorder Interview (ASDI) questionnaire, in addition to war-related exposure and demographic data. The majority of respondents experienced at least one of four symptom groups of ASD, 5.5% of the Jewish respondents and 20.3% of the Arabs met the criteria of ASD. Higher rates of Arab respondents reported symptoms of dissociation, reexperiencing and arousal, but a similar rate of avoidance was reported by the two samples. Higher mean scores of ASS and of symptoms-related impairment were reported by the Arab respondents. According to multiple regression analyses, younger age, female gender, Arab ethnicity and experiencing the war more intensely as a stressor significantly explained ASS variance, while Arab ethnicity and proximity to missiles exploding significantly explained the variance of symptoms-related impairment. A substantial rate of participants experienced symptoms of acute stress, while for only small proportion were the symptoms consistent with ASD. Higher ASD and ASS were reported by the Arab sample, calling attention to the need to build interventions to reduce the present symptoms and to help prepare for possible similar situations in the future.

Apparatus for microbiological sampling. [including automatic swabbing

NASA Technical Reports Server (NTRS)

Wilkins, J. R.; Mills, S. M. (Inventor)

1974-01-01

An automatic apparatus is described for microbiologically sampling surface using a cotton swab which eliminates human error. The apparatus includes a self-powered transport device, such as a motor-driven wheeled cart, which mounts a swabbing motor drive for a crank arm which supports a swab in the free end thereof. The swabbing motor is pivotably mounted and an actuator rod movable responsive to the cart traveling a predetermined distance provides lifting of the swab from the surface being sampled and reversal of the direction of travel of the cart.

Validity of the CAGE questionnaire for men who have sex with men (MSM) in China.

PubMed

Chen, Yen-Tyng; Ibragimov, Umedjon; Nehl, Eric J; Zheng, Tony; He, Na; Wong, Frank Y

2016-03-01

Detection of heavy drinking among men who have sex with men (MSM) is crucial for both intervention and treatment. The CAGE questionnaire is a popular screening instrument for alcohol use problems. However, the validity of CAGE for Chinese MSM is unknown. Data were from three waves of cross-sectional assessments among general MSM (n=523) and men who sell sex to other men ("money boys" or MBs, n=486) in Shanghai, China. Specifically, participants were recruited using respondent-driven, community popular opinion leader, and venue-based sampling methods. The validity of the CAGE was examined for different cutoff scores and individual CAGE items using self-reported heavy drinking (≥14 drinks in the past week) as a criterion. In the full sample, 75 (7.4%) of participants were classified as heavy drinkers. 32 (6.1%) of general MSM and 43 (8.9%) of MBs were heavy drinkers. The area under curve statistics for overall sample was 0.7 (95% CI: 0.36-0.77). Overall, the sensitivities (ranging from 18.7 to 66.7%), specificities (ranging from 67.5 to 95.8%), and positive predictive values (ranging from 14.1 to 26.4%) for different cutoff scores were inadequate using past week heavy drinking as the criterion. The ability of CAGE to discriminate heavy drinkers from non-heavy drinkers was limited. Our findings showed the inadequate validity of CAGE as a screening instrument for current heavy drinking in Chinese MSM. Further research using a combination of validity criteria is needed to determine the applicability of CAGE for this population. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

HIV seroprevalence and high-risk sexual behavior among female sex workers in Central Brazil.

PubMed

Fernandes, Fernanda R P; Mousquer, Gina J; Castro, Lisie S; Puga, Marco A; Tanaka, Tayana S O; Rezende, Grazielli R; Pinto, Clarice S; Bandeira, Larissa M; Martins, Regina M B; Francisco, Roberta B L; Teles, Sheila A; Motta-Castro, Ana R C

2014-01-01

Female sex workers (FSWs) are considered a high-risk group for human immunodeficiency virus (HIV) infection due to their social vulnerability and factors associated with their work. We estimated the prevalence of HIV, and identified viral subtypes and risk factors among FSWs. A cross-sectional study using respondent-driven sampling (RDS) method was conducted among 402 FSWs in Campo Grande city, Brazil, from 2009 to 2011. Participants were interviewed using a standardized questionnaire about sociodemograpic characteristics and risk behavior. Blood samples were collected for serological testing of HIV. Of the 402 FSWs, median age and age of initiating sex work were 25 years (Interquartile range [IQR]: 9) and 20 years (IQR: 6), respectively. The majority reported use of alcohol (88.5%), had 5-9 years (median: 9; IQR: 3) of schooling (54.5%), 68.6% had tattoos/body piercings, and 45.1% had more than seven clients per week (median: 7; IQR: 10). Only 32.9% of FSW reported using a condom with nonpaying partners in the last sexual contact. Prevalence of HIV infection was 1.0% (95% CI: 0.1-2.6%). Genotyping for HIV-1 performed on three samples detected subtypes B, C, and F1. Sex work in the Midwestern region of Brazil is characterized by reduced education, large numbers of clients per week, and inconsistent condom use, mainly with nonpaying partners. Although prevalence of HIV infection is currently low, elevated levels of high-risk sexual behavior confirm a need to implement prevention measures. Specific interventions targeting FSWs must emphasize the risk associated with both clients and nonpaying partners while providing knowledge about HIV prevention.

Male-on-male intimate partner violence and sexual risk behaviors among money boys and other men who have sex with men in Shanghai, China.

PubMed

Dunkle, Kristin L; Wong, Frank Y; Nehl, Eric J; Lin, Lavinia; He, Na; Huang, Jennifer; Zheng, Tony

2013-05-01

Intimate partner violence (IPV) is known to increase HIV risk among heterosexual women, but less is known about IPV and HIV among men who have sex with men (MSM), with almost no data from non-Western countries. This study examined the prevalence of IPV and links between IPV and HIV risks among MSM in Shanghai, China. A cross-sectional sample of 404 money boys (male sex workers) and other MSM were recruited via respondent-driven sampling. Overall, 51% of the sample reported emotional, physical, or sexual abuse from a male sexual partner. Money boys reported more overall abuse than did other MSM, and more were likely than other MSM to report experiencing multiple types of abuse. MSM who reported violence or abuse from male partners reported more overall sexual risk behavior, and specifically, more unprotected sex and more sex linked to alcohol and other substance use. The association between experience of abuse from male partners and increased HIV risk did not differ between money boys and other Chinese MSM. We conclude that violence and abuse from male partners are highly prevalent among Chinese MSM, and that experience of violence from male sexual partners is linked to increased HIV risk. HIV prevention targeting Chinese MSM must address the increased risk associated with experience of male-on-male IPV. Future research should explore links between HIV risk and MSM's perpetration of violence against male partners, as well as exploring the role of violence in the male-female relationships of men who have sex with and men and women.

Community viral load, antiretroviral therapy coverage, and HIV incidence in India: A cross-sectional, comparative evaluation study

PubMed Central

Solomon, Sunil Suhas; Mehta, Shruti H; McFall, Allison M; Srikrishnan, Aylur K; Saravanan, Shanmugam; Laeyendecker, Oliver; Balakrishnan, Pachamuthu; Celentano, David D; Solomon, Suniti; Lucas, Gregory M

2016-01-01

Introduction The concept of community viral load as a modifiable driver of new HIV infections has attracted substantial attention. While several measures of community viral load have been proposed, none have been empirically compared as correlates of HIV incidence. Methods In a sample of 26,503 people who inject drugs (PWID) and men who have sex with men (MSM) recruited using respondent-driven sampling from 27 sites in India, we assessed site-level correlations between five community-based measures of HIV control and HIV incidence - estimated with a multi-assay algorithm. Antiretroviral therapy (ART) use was self-reported. All subjects were tested for HIV, with additional testing in HIV-positive participants. Population viral load (PVL), aware viral load (AVL), and in-care viral load (ICVL), were the mean log10 HIV RNA among all HIV-positive persons, those aware of their diagnosis (but not necessarily in care), and those in care, respectively. Population ART coverage was defined as the proportion of HIV-positive subjects taking ART and prevalence of viremia as the prevalence of HIV-positive individuals with HIV RNA>150 copies/ml. Findings Prevalence of viremia (ρ=0.81) was significantly more correlated with HIV incidence than all other measures including ICVL (ρ=0.29), AVL (ρ=0.59), PVL (ρ=0.51) and population ART coverage (ρ=−0.54). In regression analysis, a reduction in prevalence of viremia of 4.34% was associated with a 1% decrease in HIV incidence. Interpretation Prevalence of viremia, which incorporates information on HIV prevalence and viremia, had the strongest correlation with HIV incidence in this sample and may be a useful measure of program effectiveness. Funding US National Institutes of Health, Elton John AIDS Foundation PMID:27036994

The burden and determinants of HIV and sexually transmitted infections in a population-based sample of female sex workers in Goa, India.

PubMed

Shahmanesh, M; Cowan, F; Wayal, S; Copas, A; Patel, V; Mabey, D

2009-02-01

Interventions targeting sex workers are central to the National AIDS Control programme of India's third 5-year plan. Understanding the way in which societal and individual factors interact to shape sex workers' vulnerability would better inform interventions. 326 female sex workers, recruited throughout Goa using respondent-driven sampling, completed interviewer-administered questionnaires. Biological samples were tested for Trichomonas vaginalis, Neisseria gonorrhoea, Chlamydia trachomatis and antibodies to herpes simplex virus type 2 (HSV-2) and HIV. Multivariate analysis was used to define the determinants of HIV infection and any bacterial sexually transmitted infection (STI). Infections were common, with 25.7% prevalence of HIV and 22.5% prevalence of bacterial STI; chlamydia 7.3%, gonorrhoea 8.9% and trichomonas 9.4%. Antibodies to HSV-2 were detected in 57.2% of women. STI were independently associated with factors reflecting gender disadvantage and disempowerment, namely young age, lack of schooling, no financial autonomy, deliberate self-harm, sexual abuse and sex work-related factors, such as having regular customers and working on the streets. Other factors associated with STI were Goan ethnicity, not having an intimate partner and being asymptomatic. Having knowledge about HIV and access to free STI services were associated with a lower likelihood of STI. HIV was independently associated with being Hindu, recent migration to Goa, lodge or brothel-based sex work and dysuria. Sex workers working in medium prevalence states of India are highly vulnerable to HIV and STI and need to be rapidly incorporated into existing interventions. Structural and gender-based determinants of HIV and STI are integral to HIV prevention strategies.

Apollo Experiment Report: Lunar-Sample Processing in the Lunar Receiving Laboratory High-Vacuum Complex

NASA Technical Reports Server (NTRS)

White, D. R.

1976-01-01

A high-vacuum complex composed of an atmospheric decontamination system, sample-processing chambers, storage chambers, and a transfer system was built to process and examine lunar material while maintaining quarantine status. Problems identified, equipment modifications, and procedure changes made for Apollo 11 and 12 sample processing are presented. The sample processing experiences indicate that only a few operating personnel are required to process the sample efficiently, safely, and rapidly in the high-vacuum complex. The high-vacuum complex was designed to handle the many contingencies, both quarantine and scientific, associated with handling an unknown entity such as the lunar sample. Lunar sample handling necessitated a complex system that could not respond rapidly to changing scientific requirements as the characteristics of the lunar sample were better defined. Although the complex successfully handled the processing of Apollo 11 and 12 lunar samples, the scientific requirement for vacuum samples was deleted after the Apollo 12 mission just as the vacuum system was reaching its full potential.