Science.gov

Sample records for addressing selection bias

  1. Addressing selection bias in dental health services research.

    PubMed

    Lee, J Y; Rozier, R G; Norton, E C; Vann, W F

    2005-10-01

    When randomization is not possible, researchers must control for non-random assignment to experimental groups. One technique for statistical adjustment for non-random assignment is through the use of a two-stage analytical technique. The purpose of this study was to demonstrate the use of this technique to control for selection bias in examining the effects of the The Supplemental Program for Women, Infants, and Children's (WIC) on dental visits. From 5 data sources, an analysis file was constructed for 49,512 children ages 1-5 years. The two-stage technique was used to control for selection bias in WIC participation, the potentially endogenous variable. Specification tests showed that WIC participation was not random and that selection bias was present. The effects of the WIC on dental use differed by 36% after adjustment for selection bias by means of the two-stage technique. This technique can be used to control for potential selection bias in dental research when randomization is not possible.

  2. Two-Year versus One-Year Head Start Program Impact: Addressing Selection Bias by Comparing Regression Modeling with Propensity Score Analysis

    ERIC Educational Resources Information Center

    Leow, Christine; Wen, Xiaoli; Korfmacher, Jon

    2015-01-01

    This article compares regression modeling and propensity score analysis as different types of statistical techniques used in addressing selection bias when estimating the impact of two-year versus one-year Head Start on children's school readiness. The analyses were based on the national Head Start secondary dataset. After controlling for…

  3. Professional Culture and Climate: Addressing Unconscious Bias

    NASA Astrophysics Data System (ADS)

    Knezek, Patricia

    2016-10-01

    Unconscious bias reflects expectations or stereotypes that influence our judgments of others (regardless of our own group). Everyone has unconscious biases. The end result of unconscious bias can be an accumulation of advantage or disadvantage that impacts the long term career success of individuals, depending on which biases they are subject to. In order to foster a professional culture and climate, being aware of these unconscious biases and mitigating against them is a first step. This is particularly important when judgements are needed, such as in cases for recruitment, choice of speakers for conferences, and even reviewing papers submitted for publication. This presentation will cover how unconscious bias manifests itself, what evidence exists to demonstrate it exists, and ways it can be addressed.

  4. Best Practices in Hiring: Addressing Unconscious Bias

    NASA Astrophysics Data System (ADS)

    Simpson, Caroline E.

    2012-01-01

    Research has shown that implementing certain hiring practices will increase diversity in the workplace while enhancing academic quality. All of these practices rely on addressing the issue of 'unconscious bias.' A brief overview of unconscious bias--what it is, how it works, and simple measures to counter it--will be presented. Successful strategies, actions, and recommendations for implementing best recruiting and hiring practices, which have been proven to enhance academic excellence by ensuring a deep and diverse applicant pool, will also be presented.

  5. Evaluating the Performance of Propensity Scores to Address Selection Bias in a Multilevel Context: A Monte Carlo Simulation Study and Application Using a National Dataset

    ERIC Educational Resources Information Center

    Lingle, Jeremy A.

    2009-01-01

    When researchers are unable to randomly assign students to treatment conditions, selection bias is introduced into the estimates of treatment effects. Random assignment to treatment conditions, which has historically been the scientific benchmark for causal inference, is often impossible or unethical to implement in educational systems. For…

  6. Addressing Unconscious Bias: Steps toward an Inclusive Scientific Culture

    NASA Astrophysics Data System (ADS)

    Stewart, Abigail

    2011-01-01

    In this talk I will outline the nature of unconscious bias, as it operates to exclude or marginalize some participants in the scientific community. I will show how bias results from non-conscious expectations about certain groups of people, including scientists and astronomers. I will outline scientific research in psychology, sociology and economics that has identified the impact these expectations have on interpersonal judgments that are at the heart of assessment of individuals' qualifications. This research helps us understand not only how bias operates within a single instance of evaluation, but how evaluation bias can accumulate over a career if not checked, creating an appearance of confirmation of biased expectations. Some research has focused on how best to interrupt and mitigate unconscious bias, and many institutions--including the University of Michigan--have identified strategic interventions at key points of institutional decision-making (particularly hiring, annual review, and promotion) that can make a difference. The NSF ADVANCE Institutional Transformation program encouraged institutions to draw on the social science literature to create experimental approaches to addressing unconscious bias. I will outline four approaches to intervention that have arisen through the ADVANCE program: (1) systematic education that increases awareness among decisionmakers of how evaluation bias operates; (2) development of practices that mitigate the operation of bias even when it is out of conscious awareness; (3) creation of institutional policies that routinize and sanction these practices; and (4) holding leaders accountable for these implementation of these new practices and policies. Although I will focus on ways to address unconscious bias within scientific institutions (colleges and universities, laboratories and research centers, etc.), I will close by considering how scientific organizations can address unconscious bias and contribute to creating an

  7. Model selection bias and Freedman's paradox

    USGS Publications Warehouse

    Lukacs, P.M.; Burnham, K.P.; Anderson, D.R.

    2010-01-01

    In situations where limited knowledge of a system exists and the ratio of data points to variables is small, variable selection methods can often be misleading. Freedman (Am Stat 37:152-155, 1983) demonstrated how common it is to select completely unrelated variables as highly "significant" when the number of data points is similar in magnitude to the number of variables. A new type of model averaging estimator based on model selection with Akaike's AIC is used with linear regression to investigate the problems of likely inclusion of spurious effects and model selection bias, the bias introduced while using the data to select a single seemingly "best" model from a (often large) set of models employing many predictor variables. The new model averaging estimator helps reduce these problems and provides confidence interval coverage at the nominal level while traditional stepwise selection has poor inferential properties. ?? The Institute of Statistical Mathematics, Tokyo 2009.

  8. Selection bias and the perils of benchmarking.

    PubMed

    Denrell, Jerker

    2005-04-01

    To find the secrets of business success, what could be more natural than studying successful businesses? In fact, nothing could be more dangerous, warns this Stanford professor. Generalizing from the examples of successful companies is like generalizing about New England weather from data taken only in the summer. That's essentially what businesspeople do when they learn from good examples and what consultants, authors, and researchers do when they study only existing companies or--worse yet--only high-performing companies. They reach conclusions from unrepresentative data samples, falling into the classic statistical trap of selection bias. Drawing on a wealth of case studies, for instance, one researcher concluded that great leaders share two key traits: They persist, often despite initial failures, and they are able to persuade others to join them. But those traits are also the hallmarks of spectacularly unsuccessful entrepreneurs, who must persist in the face of failure to incur large losses and must be able to persuade others to pour their money down the drain. To discover what makes a business successful, then, managers should look at both successes and failures. Otherwise, they will overvalue risky business practices, seeing only those companies that won big and not the ones that lost dismally. They will not be able to tell if their current good fortune stems from smart business practices or if they are actually coasting on past accomplishments or good luck. Fortunately, economists have developed relatively simple tools that can correct for selection bias even when data about failed companies are hard to come by. Success may be inspirational, but managers are more likely to find the secrets of high performance if they give the stories of their competitors'failures as full a hearing as they do the stories of dazzling successes.

  9. Selection bias and the perils of benchmarking.

    PubMed

    Denrell, Jerker

    2005-04-01

    To find the secrets of business success, what could be more natural than studying successful businesses? In fact, nothing could be more dangerous, warns this Stanford professor. Generalizing from the examples of successful companies is like generalizing about New England weather from data taken only in the summer. That's essentially what businesspeople do when they learn from good examples and what consultants, authors, and researchers do when they study only existing companies or--worse yet--only high-performing companies. They reach conclusions from unrepresentative data samples, falling into the classic statistical trap of selection bias. Drawing on a wealth of case studies, for instance, one researcher concluded that great leaders share two key traits: They persist, often despite initial failures, and they are able to persuade others to join them. But those traits are also the hallmarks of spectacularly unsuccessful entrepreneurs, who must persist in the face of failure to incur large losses and must be able to persuade others to pour their money down the drain. To discover what makes a business successful, then, managers should look at both successes and failures. Otherwise, they will overvalue risky business practices, seeing only those companies that won big and not the ones that lost dismally. They will not be able to tell if their current good fortune stems from smart business practices or if they are actually coasting on past accomplishments or good luck. Fortunately, economists have developed relatively simple tools that can correct for selection bias even when data about failed companies are hard to come by. Success may be inspirational, but managers are more likely to find the secrets of high performance if they give the stories of their competitors'failures as full a hearing as they do the stories of dazzling successes. PMID:15807044

  10. How Hispanic Patients Address Ambiguous versus Unambiguous Bias in the Doctor's Office

    PubMed Central

    Bean, Meghan G.; Covarrubias, Rebecca; Stone, Jeff

    2014-01-01

    Two studies examined Hispanic individuals’ preferences for using ten different bias reduction strategies when interacting with a doctor whose beliefs about their group were either ambiguous or clearly biased. Consistent with predictions, participants who imagined interacting with a doctor whose beliefs were ambiguous preferred strategies that facilitate positive doctor-patient interactions, whereas participants whose doctor explicitly endorsed negative stereotypes about their group preferred strategies that address stereotype content. The results also revealed that, regardless of whether the doctor's beliefs were ambiguous or clearly biased, stigma consciousness predicted participants’ preferences for using strategies that address stereotype content. These findings suggest that both doctors’ behavior and individual-level factors influence how minority individuals choose to behave in a healthcare setting. PMID:25395691

  11. Bias in Testing: A Presentation of Selected Methods.

    ERIC Educational Resources Information Center

    Merz, William R.; Rudner, Lawrence M.

    A variety of terms related to test bias or test fairness have been used in a variety of ways, but in this document the "fair use of tests" is defined as equitable selection procedures by means of intact tests, and "test item bias" refers to the study of separate items with respect to the tests of which they are a part. Seven different operational…

  12. Meta-Regression Approximations to Reduce Publication Selection Bias

    ERIC Educational Resources Information Center

    Stanley, T. D.; Doucouliagos, Hristos

    2014-01-01

    Publication selection bias is a serious challenge to the integrity of all empirical sciences. We derive meta-regression approximations to reduce this bias. Our approach employs Taylor polynomial approximations to the conditional mean of a truncated distribution. A quadratic approximation without a linear term, precision-effect estimate with…

  13. Target selection biases from recent experience transfer across effectors.

    PubMed

    Moher, Jeff; Song, Joo-Hyun

    2016-02-01

    Target selection is often biased by an observer's recent experiences. However, not much is known about whether these selection biases influence behavior across different effectors. For example, does looking at a red object make it easier to subsequently reach towards another red object? In the current study, we asked observers to find the uniquely colored target object on each trial. Randomly intermixed pre-trial cues indicated the mode of action: either an eye movement or a visually guided reach movement to the target. In Experiment 1, we found that priming of popout, reflected in faster responses following repetition of the target color on consecutive trials, occurred regardless of whether the effector was repeated from the previous trial or not. In Experiment 2, we examined whether an inhibitory selection bias away from a feature could transfer across effectors. While priming of popout reflects both enhancement of the repeated target features and suppression of the repeated distractor features, the distractor previewing effect isolates a purely inhibitory component of target selection in which a previewed color is presented in a homogenous display and subsequently inhibited. Much like priming of popout, intertrial suppression biases in the distractor previewing effect transferred across effectors. Together, these results suggest that biases for target selection driven by recent trial history transfer across effectors. This indicates that representations in memory that bias attention towards or away from specific features are largely independent from their associated actions. PMID:26563393

  14. Target selection bias transfers across different response actions

    PubMed Central

    Moher, Jeff; Song, Joo-Hyun

    2014-01-01

    Target selection is biased by recent experience. For example, a selected target feature may be stored in memory and bias selection on future trials, such that objects matching that feature are “primed” for selection. In the present study, we examined the role of action history in selection biases. Participants searched for a uniquely colored object. Pre-trial cues indicated whether participants should respond with a keypress or a reach movement. If the representation of the feature that biases selection is critically bound with its associated action, we would expect priming effects to be restricted to cases where both the response mode and target color are repeated. However, we found that responses to the target were faster when the target color was repeated, even when the response switched from a reach to a keypress, or vice versa. Priming effects were even observed following “no-go” trials where a response was withheld, and priming effects transferred across response modes when eye movement recordings ensured that participants did not saccade to the target. These results demonstrate that target features are represented in memory separately from their associated actions and can bias selection on subsequent trials even when a different mode of action output is required. PMID:24490945

  15. Biased selection within the social health insurance market in Colombia.

    PubMed

    Castano, Ramon; Zambrano, Andres

    2006-12-01

    Reducing the impact of insurance market failures with regulations such as community-rated premiums, standardized benefit packages and open enrolment, yield limited effect because they create room for selection bias. The Colombian social health insurance system started a market approach in 1993 expecting to improve performance of preexisting monopolistic insurance funds by exposing them to competition by new entrants. This paper tests the hypothesis that market failures would lead to biased selection favoring new entrants. Two household surveys are analyzed using Self-Reported Health Status and the presence of chronic conditions as prospective indicators of individual risk. Biased selection is found to take place, leading to adverse selection among incumbents, and favorable selection among new entrants. This pattern is absent in 1997 but is evident in 2003. Given that the two incumbents analyzed are public organizations, the fiscal implications of the findings in terms of government bailouts, are analyzed. PMID:16516333

  16. Brief Report: Negative Controls to Detect Selection Bias and Measurement Bias in Epidemiologic Studies

    PubMed Central

    Ercumen, Ayse; Benjamin-Chung, Jade; Colford, John M.

    2016-01-01

    Biomedical laboratory experiments routinely use negative controls to identify possible sources of bias, but epidemiologic studies have infrequently used this type of control in their design or measurement approach. Recently, epidemiologists proposed the routine use of negative controls in observational studies and defined the structure of negative controls to detect bias due to unmeasured confounding. We extend this previous study and define the structure of negative controls to detect selection bias and measurement bias in both observational studies and randomized trials. We illustrate the strengths and limitations of negative controls in this context using examples from the epidemiologic literature. Given their demonstrated utility and broad generalizability, the routine use of prespecified negative controls will strengthen the evidence from epidemiologic studies. PMID:27182642

  17. Measuring the Determinants of School Completion in Pakistan: Analysis of Censoring and Selection Bias.

    ERIC Educational Resources Information Center

    Holmes, Jessica

    2003-01-01

    Examines the demand for schooling in Pakistan, focusing on two potential sources of bias in the estimation of that demand: censoring bias and selection bias. Finds evidence of both biases. (Contains 51 references.) (PKP)

  18. The Importance of Covariate Selection in Controlling for Selection Bias in Observational Studies

    ERIC Educational Resources Information Center

    Steiner, Peter M.; Cook, Thomas D.; Shadish, William R.; Clark, M. H.

    2010-01-01

    The assumption of strongly ignorable treatment assignment is required for eliminating selection bias in observational studies. To meet this assumption, researchers often rely on a strategy of selecting covariates that they think will control for selection bias. Theory indicates that the most important covariates are those highly correlated with…

  19. Meta-regression approximations to reduce publication selection bias.

    PubMed

    Stanley, T D; Doucouliagos, Hristos

    2014-03-01

    Publication selection bias is a serious challenge to the integrity of all empirical sciences. We derive meta-regression approximations to reduce this bias. Our approach employs Taylor polynomial approximations to the conditional mean of a truncated distribution. A quadratic approximation without a linear term, precision-effect estimate with standard error (PEESE), is shown to have the smallest bias and mean squared error in most cases and to outperform conventional meta-analysis estimators, often by a great deal. Monte Carlo simulations also demonstrate how a new hybrid estimator that conditionally combines PEESE and the Egger regression intercept can provide a practical solution to publication selection bias. PEESE is easily expanded to accommodate systematic heterogeneity along with complex and differential publication selection bias that is related to moderator variables. By providing an intuitive reason for these approximations, we can also explain why the Egger regression works so well and when it does not. These meta-regression methods are applied to several policy-relevant areas of research including antidepressant effectiveness, the value of a statistical life, the minimum wage, and nicotine replacement therapy. PMID:26054026

  20. Onset rivalry: factors that succeed and fail to bias selection.

    PubMed

    Attarha, Mouna; Moore, Cathleen M

    2015-02-01

    This project examined whether previous visual history can bias perceptual dominance during onset rivalry. A predictive sequence of non-rivalrous stimuli preceded dichoptically presented rivalrous displays. One of the dichoptic images was the implied next step of the preceding sequence while the other was not. Observers reported their initial dominant percept. Across five experiments, we found that motion sequences biased perceptual selection such that a rivalrous stimulus that continued a motion sequence tended to dominate one that did not. However, signals generated by complex pattern of motion information or verbal-semantic information had no influence on selection. These results are consistent with the view that onset rivalry is an early phase of rivalry that is likely insensitive to modulation by factors originating beyond the visual system.

  1. Selecting class weights to minimize classification bias in acreage estimation

    NASA Technical Reports Server (NTRS)

    Belcher, W. M.; Minter, T. C.

    1976-01-01

    Preliminary results of experiments being performed to select optimal class weights for use with the maximum likelihood classifier in acreage estimation using remote sensor imagery are presented. These weights will be optimal in the sense that the bias will be minimized in the proportion estimate obtained from the classification results by sample counting. The procedure was tested using Landsat MSS data from an 8 by 9.6 km area of ground truth in Finney County, Kansas.

  2. Selection bias at the heterosexual HIV-1 transmission bottleneck

    PubMed Central

    Carlson, Jonathan M.; Schaefer, Malinda; Monaco, Daniela C.; Batorsky, Rebecca; Claiborne, Daniel T.; Prince, Jessica; Deymier, Martin J.; Ende, Zachary S.; Klatt, Nichole R.; DeZiel, Charles E.; Lin, Tien-Ho; Peng, Jian; Seese, Aaron M.; Shapiro, Roger; Frater, John; Ndung’u, Thumbi; Tang, Jianming; Goepfert, Paul; Gilmour, Jill; Price, Matt A.; Kilembe, William; Heckerman, David; Goulder, Philip J.R.; Allen, Todd M.; Allen, Susan; Hunter, Eric

    2014-01-01

    SUMMARY Introduction Heterosexual HIV-1 transmission is an inefficient process with rates reported at <1% per unprotected sexual exposure. When transmission occurs, systemic infection is typically established by a single genetic variant, taken from the swarm of genetically distinct viruses circulating in the donor. Whether that founder virus represents a chance event or was systematically favored is unclear. Our work has tested a central hypothesis that founder virus selection is biased toward certain genetic characteristics. Rationale If HIV-1 transmission involves selection for viruses with certain favorable characteristics, then such advantages should emerge as statistical biases when viewed across many viral loci in many transmitting partners. We therefore identified 137 Zambian heterosexual transmission pairs, for whom plasma samples were available for both the donor and recipient partner soon after transmission, and compared the viral sequences obtained from each partner to identify features that predicted whether the majority amino acid observed at any particular position in the donor was transmitted. We focused attention on two features: viral genetic characteristics that correlate with viral fitness, and clinical factors that influence transmission. Statistical modeling indicates that the former will be favored for transmission, while the latter will nullify this relative advantage. Results We observed a highly significant selection bias that favors the transmission of amino acids associated with increased fitness. These features included the frequency of the amino acid in the study cohort, the relative advantage of the amino acid with respect to the stability of the protein, and features related to immune escape and compensation. This selection bias was reduced in couples with high risk of transmission. In particular, significantly less selection bias was observed in women and in men with genital inflammation, compared to healthy men, suggesting a more

  3. Estimating Sampling Selection Bias in Human Genetics: A Phenomenological Approach

    PubMed Central

    Risso, Davide; Taglioli, Luca; De Iasio, Sergio; Gueresi, Paola; Alfani, Guido; Nelli, Sergio; Rossi, Paolo; Paoli, Giorgio; Tofanelli, Sergio

    2015-01-01

    This research is the first empirical attempt to calculate the various components of the hidden bias associated with the sampling strategies routinely-used in human genetics, with special reference to surname-based strategies. We reconstructed surname distributions of 26 Italian communities with different demographic features across the last six centuries (years 1447–2001). The degree of overlapping between "reference founding core" distributions and the distributions obtained from sampling the present day communities by probabilistic and selective methods was quantified under different conditions and models. When taking into account only one individual per surname (low kinship model), the average discrepancy was 59.5%, with a peak of 84% by random sampling. When multiple individuals per surname were considered (high kinship model), the discrepancy decreased by 8–30% at the cost of a larger variance. Criteria aimed at maximizing locally-spread patrilineages and long-term residency appeared to be affected by recent gene flows much more than expected. Selection of the more frequent family names following low kinship criteria proved to be a suitable approach only for historically stable communities. In any other case true random sampling, despite its high variance, did not return more biased estimates than other selective methods. Our results indicate that the sampling of individuals bearing historically documented surnames (founders' method) should be applied, especially when studying the male-specific genome, to prevent an over-stratification of ancient and recent genetic components that heavily biases inferences and statistics. PMID:26452043

  4. Estimating Sampling Selection Bias in Human Genetics: A Phenomenological Approach.

    PubMed

    Risso, Davide; Taglioli, Luca; De Iasio, Sergio; Gueresi, Paola; Alfani, Guido; Nelli, Sergio; Rossi, Paolo; Paoli, Giorgio; Tofanelli, Sergio

    2015-01-01

    This research is the first empirical attempt to calculate the various components of the hidden bias associated with the sampling strategies routinely-used in human genetics, with special reference to surname-based strategies. We reconstructed surname distributions of 26 Italian communities with different demographic features across the last six centuries (years 1447-2001). The degree of overlapping between "reference founding core" distributions and the distributions obtained from sampling the present day communities by probabilistic and selective methods was quantified under different conditions and models. When taking into account only one individual per surname (low kinship model), the average discrepancy was 59.5%, with a peak of 84% by random sampling. When multiple individuals per surname were considered (high kinship model), the discrepancy decreased by 8-30% at the cost of a larger variance. Criteria aimed at maximizing locally-spread patrilineages and long-term residency appeared to be affected by recent gene flows much more than expected. Selection of the more frequent family names following low kinship criteria proved to be a suitable approach only for historically stable communities. In any other case true random sampling, despite its high variance, did not return more biased estimates than other selective methods. Our results indicate that the sampling of individuals bearing historically documented surnames (founders' method) should be applied, especially when studying the male-specific genome, to prevent an over-stratification of ancient and recent genetic components that heavily biases inferences and statistics. PMID:26452043

  5. Estimating Sampling Selection Bias in Human Genetics: A Phenomenological Approach.

    PubMed

    Risso, Davide; Taglioli, Luca; De Iasio, Sergio; Gueresi, Paola; Alfani, Guido; Nelli, Sergio; Rossi, Paolo; Paoli, Giorgio; Tofanelli, Sergio

    2015-01-01

    This research is the first empirical attempt to calculate the various components of the hidden bias associated with the sampling strategies routinely-used in human genetics, with special reference to surname-based strategies. We reconstructed surname distributions of 26 Italian communities with different demographic features across the last six centuries (years 1447-2001). The degree of overlapping between "reference founding core" distributions and the distributions obtained from sampling the present day communities by probabilistic and selective methods was quantified under different conditions and models. When taking into account only one individual per surname (low kinship model), the average discrepancy was 59.5%, with a peak of 84% by random sampling. When multiple individuals per surname were considered (high kinship model), the discrepancy decreased by 8-30% at the cost of a larger variance. Criteria aimed at maximizing locally-spread patrilineages and long-term residency appeared to be affected by recent gene flows much more than expected. Selection of the more frequent family names following low kinship criteria proved to be a suitable approach only for historically stable communities. In any other case true random sampling, despite its high variance, did not return more biased estimates than other selective methods. Our results indicate that the sampling of individuals bearing historically documented surnames (founders' method) should be applied, especially when studying the male-specific genome, to prevent an over-stratification of ancient and recent genetic components that heavily biases inferences and statistics.

  6. Selective Attention in Multi-Chip Address-Event Systems

    PubMed Central

    Bartolozzi, Chiara; Indiveri, Giacomo

    2009-01-01

    Selective attention is the strategy used by biological systems to cope with the inherent limits in their available computational resources, in order to efficiently process sensory information. The same strategy can be used in artificial systems that have to process vast amounts of sensory data with limited resources. In this paper we present a neuromorphic VLSI device, the “Selective Attention Chip” (SAC), which can be used to implement these models in multi-chip address-event systems. We also describe a real-time sensory-motor system, which integrates the SAC with a dynamic vision sensor and a robotic actuator. We present experimental results from each component in the system, and demonstrate how the complete system implements a real-time stimulus-driven selective attention model. PMID:22346689

  7. Incomplete Reporting: Addressing the Prevalence of Outcome-Reporting Bias in Educational Research

    ERIC Educational Resources Information Center

    Trainor, Brian; Polanin, Joshua; Williams, Ryan; Pigott, Terri

    2015-01-01

    Outcome reporting bias refers to the practice of omitting from primary studies outcomes that were actually collected. When primary studies do not report on all the outcomes assessed, there is an incomplete understanding of a phenomenon that may be compounded when the study is included in a systematic review of research. Outcome reporting bias is…

  8. Gender Wage Gap Accounting: The Role of Selection Bias.

    PubMed

    Bar, Michael; Kim, Seik; Leukhina, Oksana

    2015-10-01

    Mulligan and Rubinstein (2008) (MR) argued that changing selection of working females on unobservable characteristics, from negative in the 1970s to positive in the 1990s, accounted for nearly the entire closing of the gender wage gap. We argue that their female wage equation estimates are inconsistent. Correcting this error substantially weakens the role of the rising selection bias (39 % versus 78 %) and strengthens the contribution of declining discrimination (42 % versus 7 %). Our findings resonate better with related literature. We also explain why our finding of positive selection in the 1970s provides additional support for MR's main hypothesis that an exogenous rise in the market value of unobservable characteristics contributed to the closing of the gender gap. PMID:26358698

  9. Gender Wage Gap Accounting: The Role of Selection Bias.

    PubMed

    Bar, Michael; Kim, Seik; Leukhina, Oksana

    2015-10-01

    Mulligan and Rubinstein (2008) (MR) argued that changing selection of working females on unobservable characteristics, from negative in the 1970s to positive in the 1990s, accounted for nearly the entire closing of the gender wage gap. We argue that their female wage equation estimates are inconsistent. Correcting this error substantially weakens the role of the rising selection bias (39 % versus 78 %) and strengthens the contribution of declining discrimination (42 % versus 7 %). Our findings resonate better with related literature. We also explain why our finding of positive selection in the 1970s provides additional support for MR's main hypothesis that an exogenous rise in the market value of unobservable characteristics contributed to the closing of the gender gap.

  10. “Fair Play”: A Videogame Designed to Address Implicit Race Bias Through Active Perspective Taking

    PubMed Central

    Kaatz, Anna; Chu, Sarah; Ramirez, Dennis; Samson-Samuel, Clem; Carnes, Molly

    2014-01-01

    Abstract Objective: Having diverse faculty in academic health centers will help diversify the healthcare workforce and reduce health disparities. Implicit race bias is one factor that contributes to the underrepresentation of Black faculty. We designed the videogame “Fair Play” in which players assume the role of a Black graduate student named Jamal Davis. As Jamal, players experience subtle race bias while completing “quests” to obtain a science degree. We hypothesized that participants randomly assigned to play the game would have greater empathy for Jamal and lower implicit race bias than participants randomized to read narrative text describing Jamal's experience. Materials and Methods: University of Wisconsin–Madison graduate students were recruited via e-mail and randomly assigned to play “Fair Play” or read narrative text through an online link. Upon completion, participants took an Implicit Association Test to measure implicit bias and answered survey questions assessing empathy toward Jamal and awareness of bias. Results: As hypothesized, gameplayers showed the least implicit bias but only when they also showed high empathy for Jamal (P=0.013). Gameplayers did not show greater empathy than text readers, and women in the text condition reported the greatest empathy for Jamal (P=0.008). However, high empathy only predicted lower levels of implicit bias among those who actively took Jamal's perspective through gameplay (P=0.014). Conclusions: A videogame in which players experience subtle race bias as a Black graduate student has the potential to reduce implicit bias, possibly because of a game's ability to foster empathy through active perspective taking. PMID:26192644

  11. A cardinal orientation bias in scene-selective visual cortex.

    PubMed

    Nasr, Shahin; Tootell, Roger B H

    2012-10-24

    It has long been known that human vision is more sensitive to contours at cardinal (horizontal and vertical) orientations, compared with oblique orientations; this is the "oblique effect." However, the real-world relevance of the oblique effect is not well understood. Experiments here suggest that this effect is linked to scene perception, via a common bias in the image statistics of scenes. This statistical bias for cardinal orientations is found in many "carpentered environments" such as buildings and indoor scenes, and some natural scenes. In Experiment 1, we confirmed the presence of a perceptual oblique effect in a specific set of scene stimuli. Using those scenes, we found that a well known "scene-selective" visual cortical area (the parahippocampal place area; PPA) showed distinctively higher functional magnetic resonance imaging (fMRI) activity to cardinal versus oblique orientations. This fMRI-based oblique effect was not observed in other cortical areas (including scene-selective areas transverse occipital sulcus and retrosplenial cortex), although all three scene-selective areas showed the expected inversion effect to scenes. Experiments 2 and 3 tested for an analogous selectivity for cardinal orientations using computer-generated arrays of simple squares and line segments, respectively. The results confirmed the preference for cardinal orientations in PPA, thus demonstrating that the oblique effect can also be produced in PPA by simple geometrical images, with statistics similar to those in scenes. Thus, PPA shows distinctive fMRI selectivity for cardinal orientations across a broad range of stimuli, which may reflect a perceptual oblique effect.

  12. Producer Biases and Kin Selection in the Evolution of Communication

    NASA Astrophysics Data System (ADS)

    Mirolli, Marco; Parisi, Domenico

    The evolution of communication requires the co-evolution of two abilities: the ability to send useful signals and the ability to react appropriately to perceived signals. This fact poses two related but distinct problems, which are often mixed up: (1) the phylogenetic problem regarding how can communication evolve if the two traits that are necessary for its emergence are complementary and seem to require each other for providing reproductive advantages; (2) the adaptive problem regarding how can communication systems that do not advantage both signallers and receivers in the same way emerge, given their altruistic character. Here we clarify the distinction, and provide some insights on how these problems can be solved in both real and artificial systems by reporting experiments on the evolution of artificial agents that have to evolve a simple food-call communication system. Our experiments show that (1) the phylogenetic problem can be solved thanks to the presence of producer biases that make agents spontaneously produce useful signals, an idea that is complementary to the well-known "receiver bias" hypothesis found in the biological literature, and (2) the adaptive problem can be solved by having agents communicate preferentially among kin, as predicted by kin selection theory. We discuss these results with respect to both the scientific understanding of the evolution of communication and the design of embodied and communicating artificial agents.

  13. Addressing University Students' Anti-Gay Bias: An Extension of the Contact Hypothesis

    ERIC Educational Resources Information Center

    Span, Sherry A.

    2011-01-01

    One method frequently employed as an intervention to reduce anti-gay bias is a lesbian, gay, and bisexual (LGB) speaker panel. These speakers share brief biographical sketches about their coming out experiences and then answer questions. A pretest/posttest control group design examined the impact of LGB speaker panels on university students'…

  14. Estimates of External Validity Bias When Impact Evaluations Select Sites Nonrandomly

    ERIC Educational Resources Information Center

    Bell, Stephen H.; Olsen, Robert B.; Orr, Larry L.; Stuart, Elizabeth A.

    2016-01-01

    Evaluations of educational programs or interventions are typically conducted in nonrandomly selected samples of schools or districts. Recent research has shown that nonrandom site selection can yield biased impact estimates. To estimate the external validity bias from nonrandom site selection, we combine lists of school districts that were…

  15. SELECTION BIAS MODELING USING OBSERVED DATA AUGMENTED WITH IMPUTED RECORD-LEVEL PROBABILITIES

    PubMed Central

    Thompson, Caroline A.; Arah, Onyebuchi A.

    2014-01-01

    PURPOSE Selection bias is a form of systematic error that can be severe in compromised study designs such as case-control studies with inappropriate selection mechanisms or follow-up studies that suffer from extensive attrition. External adjustment for selection bias is commonly undertaken when such bias is suspected, but the methods used can be overly simplistic, if not unrealistic, and fail to allow for simultaneous adjustment of associations of the exposure and covariates with the outcome, when of interest. Internal adjustment for selection bias via inverse-probability-weighting allows bias parameters to vary with levels of covariates but has only been formalized for longitudinal studies with covariate data on patients up until loss-to-follow-up. METHODS We demonstrate the use of inverse-probability-weighting and externally obtained bias parameters to perform internal adjustment of selection bias in studies lacking covariate data on unobserved participants. RESULTS The ‘true’ or selection-adjusted odds ratio for the association between exposure and outcome was successfully obtained by analyzing only data on those in the selected stratum (i.e. responders) weighted by the inverse probability of their being selected as function of their observed covariate data. CONCLUSIONS This internal adjustment technique using user-supplied bias parameters and inverse-probability-weighting for selection bias can be applied to any type of observational study. PMID:25175700

  16. Social desirability bias in personality testing: implications for astronaut selection.

    PubMed

    Sandal, Gro M; Musson, Dave; Helmreich, Robert L; Gravdal, Lene

    2005-01-01

    The assessment of personality is recognized by space agencies as an approach to identify candidates likely to perform optimally during spaceflights. In the use of personality scales for selection, the impact of social desirability (SD) has been cited as a concern. Study 1 addressed the impact of SD on responses to the Personality Characteristic Inventory(PCI) and NEO-FFI. This was achieved by contrasting scores from active astronauts (N=65) with scores of successful astronaut applicants (N=63), and between pilots applicants (N=1271) and pilot research subjects (N=120). Secondly, personality scores were correlated with scores on the Marlow Crown Social Desirability Scale among applicants to managerial positions (N=120). The results indicated that SD inflated scores on PCI scales assessing negative interpersonal characteristics, and impacted on four of five scales in NEO-FFI. Still, the effect sizes were small or moderate. Study 2 addressed performance implications of SD during an assessment of males applying to work as rescue personnel operations in the North Sea (N=22). The results showed that SD correlated negatively with cognitive test performance, and positively with discrepancy in performance ratings between self and two observers. In conclusion, caution is needed in interpreting personality scores in applicant populations. SD maybe a negative predictor for performance under stress.

  17. An Evaluation of Select Approaches For Biased Item Identification.

    ERIC Educational Resources Information Center

    Rudner, Lawrence M.; Convey, John J.

    Transformed item difficulties, chi-square, item characteristic curve (icc) theory and factor score techniques were evaluated as approaches for the identification of biased test items. The study was implemented to determine whether the approaches would provide identical classifications of items as to degree of aberrance for culturally different…

  18. A Treatment Package without Escape Extinction to Address Food Selectivity.

    PubMed

    Weber, Jessica; Gutierrez, Anibal

    2015-08-21

    Feeding difficulties and feeding disorders are a commonly occurring problem for young children, particularly children with developmental delays including autism. Behavior analytic interventions for the treatment of feeding difficulties oftentimes include escape extinction as a primary component of treatment. The use of escape extinction, while effective, may be problematic as it is also associated with the emergence of challenging behavior (e.g., extinction burst). Such challenging behavior may be an acceptable side effect in treatment cases where feeding problems are severe and chronic (e.g., failure to thrive). However, in more acute cases (e.g., selective eating), the negative side effect may be unwarranted and undesired. More recent research on the behavioral treatment of food selectivity has begun to evaluate treatments for feeding difficulties that do not include escape extinction (e.g., demand fading, behavioral momentum), with some success. However, research to date reveals individual differences in responsiveness to such treatments and no clear preferable treatment has emerged. This manuscript describes a multi-component treatment package that includes shaping, sequential presentation and simultaneous presentation, for the treatment of food selectivity in four young children with developmental delays. This treatment package extends the literature on the behavioral treatment for food selectivity and offers a multi-component treatment protocol that may be clinically applicable across a range of treatment scenarios and settings.

  19. Do local and global perceptual biases tell us anything about local and global selective attention?

    PubMed

    Caparos, Serge; Linnell, Karina J; Bremner, Andrew J; de Fockert, Jan W; Davidoff, Jules

    2013-02-01

    Local, as opposed to global, perceptual bias has been linked to a lesser ability to attend globally. We examined this proposed link in Himba observers, members of a remote Namibian population who have demonstrated a strong local bias compared with British observers. If local perceptual bias is related to a lesser ability to attend globally, Himba observers, relative to British observers, should be less distracted by global information when performing a local-selection task but more distracted by local information when performing a global-selection task. However, Himba observers performed better than British observers did on both a local-selection task and a global-selection task (both of which used local/global hierarchical figures as stimuli), which suggests that they possessed greater control over attentional selection in response to task demands. We conclude that local and global perceptual biases must be distinguished from local and global selective attention.

  20. Investigation on particle swarm optimisation for feature selection on high-dimensional data: local search and selection bias

    NASA Astrophysics Data System (ADS)

    Tran, Binh; Xue, Bing; Zhang, Mengjie; Nguyen, Su

    2016-07-01

    Feature selection is an essential step in classification tasks with a large number of features, such as in gene expression data. Recent research has shown that particle swarm optimisation (PSO) is a promising approach to feature selection. However, it also has potential limitation to get stuck into local optima, especially for gene selection problems with a huge search space. Therefore, we developed a PSO algorithm (PSO-LSRG) with a fast "local search" combined with a gbest resetting mechanism as a way to improve the performance of PSO for feature selection. Furthermore, since many existing PSO-based feature selection approaches on the gene expression data have feature selection bias, i.e. no unseen test data is used, 2 sets of experiments on 10 gene expression datasets were designed: with and without feature selection bias. As compared to standard PSO, PSO with gbest resetting only, and PSO with local search only, PSO-LSRG obtained a substantial dimensionality reduction and a significant improvement on the classification performance in both sets of experiments. PSO-LSRG outperforms the other three algorithms when feature selection bias exists. When there is no feature selection bias, PSO-LSRG selects the smallest number of features in all cases, but the classification performance is slightly worse in a few cases, which may be caused by the overfitting problem. This shows that feature selection bias should be avoided when designing a feature selection algorithm to ensure its generalisation ability on unseen data.

  1. Bias Reduction in Quasi-Experiments with Little Selection Theory but Many Covariates

    ERIC Educational Resources Information Center

    Steiner, Peter M.; Cook, Thomas D.; Li, Wei; Clark, M. H.

    2015-01-01

    In observational studies, selection bias will be completely removed only if the selection mechanism is ignorable, namely, all confounders of treatment selection and potential outcomes are reliably measured. Ideally, well-grounded substantive theories about the selection process and outcome-generating model are used to generate the sample of…

  2. Sex-Specific Selection and Sex-Biased Gene Expression in Humans and Flies

    PubMed Central

    Kirkpatrick, Mark

    2016-01-01

    Sexual dimorphism results from sex-biased gene expression, which evolves when selection acts differently on males and females. While there is an intimate connection between sex-biased gene expression and sex-specific selection, few empirical studies have studied this relationship directly. Here we compare the two on a genome-wide scale in humans and flies. We find a distinctive “Twin Peaks” pattern in humans that relates the strength of sex-specific selection, quantified by genetic divergence between male and female adults at autosomal loci, to the degree of sex-biased expression. Genes with intermediate degrees of sex-biased expression show evidence of ongoing sex-specific selection, while genes with either little or completely sex-biased expression do not. This pattern apparently results from differential viability selection in males and females acting in the current generation. The Twin Peaks pattern is also found in Drosophila using a different measure of sex-specific selection acting on fertility. We develop a simple model that successfully recapitulates the Twin Peaks. Our results suggest that many genes with intermediate sex-biased expression experience ongoing sex-specific selection in humans and flies. PMID:27658217

  3. Sample Selection Bias in Analysis of Consumer Choice: An Application to Warmwater Fishing Demand

    NASA Astrophysics Data System (ADS)

    Ziemer, Rod F.; Musser, Wesley N.; White, Fred C.; Hill, R. Carter

    1982-04-01

    A theoretical model and empirical application are presented which account for the individual's decision concerning whether or not to recreate as well as the amount of participation once the decision is made. Results for warmwater fishing demand data yielded least squares parameter estimates fairly similar to those provided by an estimator which corrects for sample selection bias. Further research appears warranted regarding the general degree of potential selection bias inherent in outdoor recreation demand data.

  4. Exploring Selective Exposure and Confirmation Bias as Processes Underlying Employee Work Happiness: An Intervention Study.

    PubMed

    Williams, Paige; Kern, Margaret L; Waters, Lea

    2016-01-01

    Employee psychological capital (PsyCap), perceptions of organizational virtue (OV), and work happiness have been shown to be associated within and over time. This study examines selective exposure and confirmation bias as potential processes underlying PsyCap, OV, and work happiness associations. As part of a quasi-experimental study design, school staff (N = 69) completed surveys at three time points. After the first assessment, some staff (n = 51) completed a positive psychology training intervention. Results of descriptive statistics, correlation, and regression analyses on the intervention group provide some support for selective exposure and confirmation bias as explanatory mechanisms. In focusing on the processes through which employee attitudes may influence work happiness this study advances theoretical understanding, specifically of selective exposure and confirmation bias in a field study context.

  5. Exploring Selective Exposure and Confirmation Bias as Processes Underlying Employee Work Happiness: An Intervention Study

    PubMed Central

    Williams, Paige; Kern, Margaret L.; Waters, Lea

    2016-01-01

    Employee psychological capital (PsyCap), perceptions of organizational virtue (OV), and work happiness have been shown to be associated within and over time. This study examines selective exposure and confirmation bias as potential processes underlying PsyCap, OV, and work happiness associations. As part of a quasi-experimental study design, school staff (N = 69) completed surveys at three time points. After the first assessment, some staff (n = 51) completed a positive psychology training intervention. Results of descriptive statistics, correlation, and regression analyses on the intervention group provide some support for selective exposure and confirmation bias as explanatory mechanisms. In focusing on the processes through which employee attitudes may influence work happiness this study advances theoretical understanding, specifically of selective exposure and confirmation bias in a field study context. PMID:27378978

  6. Exploring Selective Exposure and Confirmation Bias as Processes Underlying Employee Work Happiness: An Intervention Study.

    PubMed

    Williams, Paige; Kern, Margaret L; Waters, Lea

    2016-01-01

    Employee psychological capital (PsyCap), perceptions of organizational virtue (OV), and work happiness have been shown to be associated within and over time. This study examines selective exposure and confirmation bias as potential processes underlying PsyCap, OV, and work happiness associations. As part of a quasi-experimental study design, school staff (N = 69) completed surveys at three time points. After the first assessment, some staff (n = 51) completed a positive psychology training intervention. Results of descriptive statistics, correlation, and regression analyses on the intervention group provide some support for selective exposure and confirmation bias as explanatory mechanisms. In focusing on the processes through which employee attitudes may influence work happiness this study advances theoretical understanding, specifically of selective exposure and confirmation bias in a field study context. PMID:27378978

  7. A field test of the extent of bias in selection estimates after accounting for emigration

    USGS Publications Warehouse

    Letcher, B.H.; Horton, G.E.; Dubreuil, T.L.; O'Donnell, M. J.

    2005-01-01

    Question: To what extent does trait-dependent emigration bias selection estimates in a natural system? Organisms: Two freshwater cohorts of Atlantic salmon (Salmo salar) juveniles. Field site: A 1 km stretch of a small stream (West Brook) in western Massachusetts. USA from which emigration could be detected continuously. Methods: Estimated viability selection differentials for body size either including or ignoring emigration (include = emigrants survived interval, ignore = emigrants did not survive interval) for 12 intervals. Results: Seasonally variable size-related emigration from our study site generated variable levels of bias in selection estimates for body size. The magnitude of this bias was closely related with the extent of size-dependent emigration during each interval. Including or ignoring the effects of emigration changed the significance of selection estimates in 5 of the 12 intervals, and changed the estimated direction of selection in 4 of the 12 intervals. These results indicate the extent to which inferences about selection in a natural system can be biased by failing to account for trait-dependent emigration. ?? 2005 Benjamin H. Letcher.

  8. Estimation and adjustment of self-selection bias in volunteer panel web surveys

    NASA Astrophysics Data System (ADS)

    Niu, Chengying

    2016-06-01

    By using propensity score matching method of random sample, we matched simple random sample units and volunteer panel Web survey sample units based on the equal or similar propensity score. The unbiased estimators of the population parameters are constructed by using the matching simple random sample, and the self-selection bias is estimated. We propose propensity score weighted and matching sample post stratification weighted methods to estimate the population parameters, and the self-selection bias in volunteer panel Web Surveys are adjusted.

  9. Bias Selectable Dual Band AlGaN Ultra-violet Detectors

    NASA Technical Reports Server (NTRS)

    Yan, Feng; Miko, Laddawan; Franz, David; Guan, Bing; Stahle, Carl M.

    2007-01-01

    Bias selectable dual band AlGaN ultra-violet (UV) detectors, which can separate UV-A and UV-B using one detector in the same pixel by bias switching, have been designed, fabricated and characterized. A two-terminal n-p-n photo-transistor-like structure was used. When a forward bias is applied between the top electrode and the bottom electrode, the detectors can successfully detect W-A and reject UV-B. Under reverse bias, they can detect UV-B and reject UV-A. The proof of concept design shows that it is feasible to fabricate high performance dual-band UV detectors based on the current AlGaN material growth and fabrication technologies.

  10. Addressing Selection Bias Using Partial Longitudinal Data: A Demonstration Using Recent and Past School Movers

    ERIC Educational Resources Information Center

    Grigg, Jeffrey

    2015-01-01

    The United States is a mobile society, and many children are caught up in currents of residential and school mobility. According to the Early Childhood Longitudinal Study, 31% of eighth grade students in 2007 had changed schools three or more times since the beginning of kindergarten. Mobile students offer potential insight into the influences of…

  11. Addressing criticisms of existing predictive bias research: cognitive ability test scores still overpredict African Americans' job performance.

    PubMed

    Berry, Christopher M; Zhao, Peng

    2015-01-01

    Predictive bias studies have generally suggested that cognitive ability test scores overpredict job performance of African Americans, meaning these tests are not predictively biased against African Americans. However, at least 2 issues call into question existing over-/underprediction evidence: (a) a bias identified by Aguinis, Culpepper, and Pierce (2010) in the intercept test typically used to assess over-/underprediction and (b) a focus on the level of observed validity instead of operational validity. The present study developed and utilized a method of assessing over-/underprediction that draws on the math of subgroup regression intercept differences, does not rely on the biased intercept test, allows for analysis at the level of operational validity, and can use meta-analytic estimates as input values. Therefore, existing meta-analytic estimates of key parameters, corrected for relevant statistical artifacts, were used to determine whether African American job performance remains overpredicted at the level of operational validity. African American job performance was typically overpredicted by cognitive ability tests across levels of job complexity and across conditions wherein African American and White regression slopes did and did not differ. Because the present study does not rely on the biased intercept test and because appropriate statistical artifact corrections were carried out, the present study's results are not affected by the 2 issues mentioned above. The present study represents strong evidence that cognitive ability tests generally overpredict job performance of African Americans.

  12. The evolution of preference strength under sensory bias: a role for indirect selection?

    PubMed Central

    Frame, Alicia M; Servedio, Maria R

    2012-01-01

    Evidence suggests that female preferences may sometimes arise through sensory bias, and that males may subsequently evolve traits that increase their conspicuousness to females. Here, we ask whether indirect selection, arising through genetic associations (linkage disequilibrium) during the sexual selection that sensory bias imposes, can itself influence the evolution of preference strength. Specifically, we use population genetic models to consider whether or not modifiers of preference strength can spread under different ecological conditions when female mate choice is driven by sensory bias. We focus on male traits that make a male more conspicuous in certain habitats—and thus both more visible to predators and more attractive to females—and examine modifiers of the strength of preference for conspicuous males. We first solve for the rate of spread of a modifier that strengthens preference within an environmentally uniform population; we illustrate that this spread will be extremely slow. Second, we used a series of simulations to consider the role of habitat structure and movement on the evolution of a modifier of preference strength, using male color polymorphisms as a case study. We find that in most cases, indirect selection does not allow the evolution of stronger or weaker preferences for sensory bias. Only in a “two-island” model, where there is restricted migration between different patches that favor different male phenotypes, did we find that preference strength could evolve. The role of indirect selection in the evolution of sensory bias is of particular interest because of ongoing speculation regarding the role of sensory bias in the evolution of reproductive isolation. PMID:22957163

  13. Educational Research with Real-World Data: Reducing Selection Bias with Propensity Scores

    ERIC Educational Resources Information Center

    Adelson, Jill L.

    2013-01-01

    Often it is infeasible or unethical to use random assignment in educational settings to study important constructs and questions. Hence, educational research often uses observational data, such as large-scale secondary data sets and state and school district data, and quasi-experimental designs. One method of reducing selection bias in estimations…

  14. Marginal Mean Weighting through Stratification: Adjustment for Selection Bias in Multilevel Data

    ERIC Educational Resources Information Center

    Hong, Guanglei

    2010-01-01

    Defining causal effects as comparisons between marginal population means, this article introduces marginal mean weighting through stratification (MMW-S) to adjust for selection bias in multilevel educational data. The article formally shows the inherent connections among the MMW-S method, propensity score stratification, and…

  15. Nursing Wages and Educational Credentials: The Role of Work Experience and Selectivity Bias.

    ERIC Educational Resources Information Center

    Botelho, Anabela; Jones, Cheryl Bland; Kiker, B. F.

    1998-01-01

    Compares registered nurses' wage profiles across three types of educational backgrounds (two-, three-, and four-year programs), allowing for alternative construction of the work-experience variable and correcting for participation selectivity and choice-of-credential biases. Results suggest that estimated wage equations are quite sensitive to the…

  16. Associations among Selective Attention, Memory Bias, Cognitive Errors and Symptoms of Anxiety in Youth

    ERIC Educational Resources Information Center

    Watts, Sarah E.; Weems, Carl F.

    2006-01-01

    The purpose of this study was to examine the linkages among selective attention, memory bias, cognitive errors, and anxiety problems by testing a model of the interrelations among these cognitive variables and childhood anxiety disorder symptoms. A community sample of 81 youth (38 females and 43 males) aged 9-17 years and their parents completed…

  17. The Effects of Sample Selection Bias on Racial Differences in Child Abuse Reporting.

    ERIC Educational Resources Information Center

    Ards, Sheila; Chung, Chanjin; Myers, Samuel L., Jr.

    1998-01-01

    Data from the National Incidence Study (NIS) of Child Abuse and Neglect suggest no racial difference in child maltreatment, although there are more black children within the child welfare population. This study found selection bias in the NIS design caused by the exclusion of family, friends, and neighbors that resulted in differences in NIS cases…

  18. Co-evolution of black holes and galaxies: the role of selection biases

    NASA Astrophysics Data System (ADS)

    Portinari, Laura

    2016-10-01

    Quasars are tracers of the cosmological evolution of the Black Hole mass- host galaxy relation, and indicate that the formation of BHanticipated that of the host galaxies. We find that selection effects andstatistical biases dominate the interpretation of the observational results;and co-evolution (= constant BH/galaxy mass ratio) is still compatiblewith observations.

  19. The Impact of Selection, Gene Conversion, and Biased Sampling on the Assessment of Microbial Demography.

    PubMed

    Lapierre, Marguerite; Blin, Camille; Lambert, Amaury; Achaz, Guillaume; Rocha, Eduardo P C

    2016-07-01

    Recent studies have linked demographic changes and epidemiological patterns in bacterial populations using coalescent-based approaches. We identified 26 studies using skyline plots and found that 21 inferred overall population expansion. This surprising result led us to analyze the impact of natural selection, recombination (gene conversion), and sampling biases on demographic inference using skyline plots and site frequency spectra (SFS). Forward simulations based on biologically relevant parameters from Escherichia coli populations showed that theoretical arguments on the detrimental impact of recombination and especially natural selection on the reconstructed genealogies cannot be ignored in practice. In fact, both processes systematically lead to spurious interpretations of population expansion in skyline plots (and in SFS for selection). Weak purifying selection, and especially positive selection, had important effects on skyline plots, showing patterns akin to those of population expansions. State-of-the-art techniques to remove recombination further amplified these biases. We simulated three common sampling biases in microbiological research: uniform, clustered, and mixed sampling. Alone, or together with recombination and selection, they further mislead demographic inferences producing almost any possible skyline shape or SFS. Interestingly, sampling sub-populations also affected skyline plots and SFS, because the coalescent rates of populations and their sub-populations had different distributions. This study suggests that extreme caution is needed to infer demographic changes solely based on reconstructed genealogies. We suggest that the development of novel sampling strategies and the joint analyzes of diverse population genetic methods are strictly necessary to estimate demographic changes in populations where selection, recombination, and biased sampling are present.

  20. The Impact of Selection, Gene Conversion, and Biased Sampling on the Assessment of Microbial Demography

    PubMed Central

    Lapierre, Marguerite; Blin, Camille; Lambert, Amaury; Achaz, Guillaume; Rocha, Eduardo P. C.

    2016-01-01

    Recent studies have linked demographic changes and epidemiological patterns in bacterial populations using coalescent-based approaches. We identified 26 studies using skyline plots and found that 21 inferred overall population expansion. This surprising result led us to analyze the impact of natural selection, recombination (gene conversion), and sampling biases on demographic inference using skyline plots and site frequency spectra (SFS). Forward simulations based on biologically relevant parameters from Escherichia coli populations showed that theoretical arguments on the detrimental impact of recombination and especially natural selection on the reconstructed genealogies cannot be ignored in practice. In fact, both processes systematically lead to spurious interpretations of population expansion in skyline plots (and in SFS for selection). Weak purifying selection, and especially positive selection, had important effects on skyline plots, showing patterns akin to those of population expansions. State-of-the-art techniques to remove recombination further amplified these biases. We simulated three common sampling biases in microbiological research: uniform, clustered, and mixed sampling. Alone, or together with recombination and selection, they further mislead demographic inferences producing almost any possible skyline shape or SFS. Interestingly, sampling sub-populations also affected skyline plots and SFS, because the coalescent rates of populations and their sub-populations had different distributions. This study suggests that extreme caution is needed to infer demographic changes solely based on reconstructed genealogies. We suggest that the development of novel sampling strategies and the joint analyzes of diverse population genetic methods are strictly necessary to estimate demographic changes in populations where selection, recombination, and biased sampling are present. PMID:26931140

  1. The Impact of Selection, Gene Conversion, and Biased Sampling on the Assessment of Microbial Demography.

    PubMed

    Lapierre, Marguerite; Blin, Camille; Lambert, Amaury; Achaz, Guillaume; Rocha, Eduardo P C

    2016-07-01

    Recent studies have linked demographic changes and epidemiological patterns in bacterial populations using coalescent-based approaches. We identified 26 studies using skyline plots and found that 21 inferred overall population expansion. This surprising result led us to analyze the impact of natural selection, recombination (gene conversion), and sampling biases on demographic inference using skyline plots and site frequency spectra (SFS). Forward simulations based on biologically relevant parameters from Escherichia coli populations showed that theoretical arguments on the detrimental impact of recombination and especially natural selection on the reconstructed genealogies cannot be ignored in practice. In fact, both processes systematically lead to spurious interpretations of population expansion in skyline plots (and in SFS for selection). Weak purifying selection, and especially positive selection, had important effects on skyline plots, showing patterns akin to those of population expansions. State-of-the-art techniques to remove recombination further amplified these biases. We simulated three common sampling biases in microbiological research: uniform, clustered, and mixed sampling. Alone, or together with recombination and selection, they further mislead demographic inferences producing almost any possible skyline shape or SFS. Interestingly, sampling sub-populations also affected skyline plots and SFS, because the coalescent rates of populations and their sub-populations had different distributions. This study suggests that extreme caution is needed to infer demographic changes solely based on reconstructed genealogies. We suggest that the development of novel sampling strategies and the joint analyzes of diverse population genetic methods are strictly necessary to estimate demographic changes in populations where selection, recombination, and biased sampling are present. PMID:26931140

  2. Born at the Wrong Time: Selection Bias in the NHL Draft

    PubMed Central

    Deaner, Robert O.; Lowen, Aaron; Cobley, Stephen

    2013-01-01

    Relative age effects (RAEs) occur when those who are relatively older for their age group are more likely to succeed. RAEs occur reliably in some educational and athletic contexts, yet the causal mechanisms remain unclear. Here we provide the first direct test of one mechanism, selection bias, which can be defined as evaluators granting fewer opportunities to relatively younger individuals than is warranted by their latent ability. Because RAEs are well-established in hockey, we analyzed National Hockey League (NHL) drafts from 1980 to 2006. Compared to those born in the first quarter (i.e., January–March), those born in the third and fourth quarters were drafted more than 40 slots later than their productivity warranted, and they were roughly twice as likely to reach career benchmarks, such as 400 games played or 200 points scored. This selection bias in drafting did not decrease over time, apparently continues to occur, and reduces the playing opportunities of relatively younger players. This bias is remarkable because it is exhibited by professional decision makers evaluating adults in a context where RAEs have been widely publicized. Thus, selection bias based on relative age may be pervasive. PMID:23460902

  3. The Effect of Selection Bias in Studies of Fads and Fashions

    PubMed Central

    Denrell, Jerker; Kovács, Balázs

    2015-01-01

    Most studies of fashion and fads focus on objects and practices that once were popular. We argue that limiting the sample to such trajectories generates a selection bias that obscures the underlying process and generates biased estimates. Through simulations and the analysis of a data set that has previously not been used to analyze the rise and fall of cultural practices, the New York Times text archive, we show that studying a whole range of cultural objects, both popular and less popular, is essential for understanding the drivers of popularity. In particular, we show that estimates of statistical models of the drivers of popularity will be biased if researchers use only trajectories of those practices that once were popular. PMID:25886158

  4. Selection bias in evaluating of influenza vaccine effectiveness: a lesson from an observational study of elderly nursing home residents.

    PubMed

    Fukushima, Wakaba; Hayashi, Yoshimitsu; Mizuno, Yaichi; Suzuki, Kanzo; Kase, Tetsuo; Ohfuji, Satoko; Fujieda, Megumi; Maeda, Akiko; Hirota, Yoshio

    2008-11-25

    Selection bias is of critical concern in the study of influenza vaccine effectiveness when using an observational study design. This bias is attributable to the inherently different characteristics between vaccinees and non-vaccinees. The differences, which are related both to vaccination and signs of clinical disease as an outcome, may lead to erroneous estimation of the effectiveness. In this report, we describe how selection bias among elderly nursing home residents may lead to a spurious interpretation of the protective effect of influenza vaccine. Our results should be a lesson in the importance of regarding selection bias when assessing influenza vaccine effectiveness.

  5. A new method of adjusting spatial and temporal biases for selected climate variables.

    NASA Astrophysics Data System (ADS)

    Grillakis, Manolis; Koutroulis, Aristeidis; Tsanis, Ioannis

    2016-04-01

    Climate models is a valuable source of data for climate change impact studies. Often, the climate model data cannot be used in their native form due to the presence of biases. The lack of an appropriate adjustment of climate forcings may even lead to unrealistic model results. Many methodologies of bias adjustment have been developed and can be found in the literature dealing with the temporal biases in the time-series. Their main task is to adjust the temporal statistical properties of climate simulations for a single point value to resemble those of observations in a common climate period. However, they do not adjust or retain the spatial patterns of the data with respect to the observational datasets. In cases where impact models are sensitive to the spatial distribution of the variables, the adjustment of the spatial patterns is equally or more important to the adjustment of the temporal statistics. Examples of such impact models are cyclone tracking schemes or coastal flooding models that consider the spatial structure of wind and/or atmospheric pressure data. Here we develop a method to deal with this type of biases in space, along with the temporal biases. The methodology considers correction in the entire spectrum of CDF data and then redistribution of the data in time, to adjust the spatial consistency against observations. The methodology is tested on surface pressure and wind data derived from selected global climate models.

  6. Selective bias in retrospective self-reports of negative mood states.

    PubMed

    Sato, Hirotsune; Kawahara, Jun-ichiro

    2011-07-01

    Retrospective self-report questionnaires of negative mood states experienced in the past (e.g., the most recent two weeks) tend to be exaggerated in a negative direction relative to the average ratings given to the moods contemporaneously. The present study used three measures that decomposed mood states into their constituent elements to examine whether certain components selectively contributed to this negative bias or all components contributed to this bias equally. Fifty-three participants responded to the questionnaires via the Internet every evening for two weeks. On the final day, participants recalled and retrospectively evaluated their mood state over the previous two weeks as a whole. The results revealed that memory bias occurred selectively for negative mood states. Anxiety, depression, and helplessness were exaggerated in the global compared with the daily ratings. None of the positive mood components showed any bias in the retrospective global ratings. A regression analysis indicated that the difference in daily and global ratings for negative mood was partly explained by peak and final scores. Higher peak scores led to greater overestimation whereas final scores had smaller effects; the higher the final score was, the less participants overestimated their negative mood in the global ratings. PMID:21253957

  7. A flexible genome-wide bootstrap method that accounts for ranking and threshold-selection bias in GWAS interpretation and replication study design.

    PubMed

    Faye, Laura L; Sun, Lei; Dimitromanolakis, Apostolos; Bull, Shelley B

    2011-07-10

    The phenomenon known as the winner's curse is a form of selection bias that affects estimates of genetic association. In genome-wide association studies (GWAS) the bias is exacerbated by the use of stringent selection thresholds and ranking over hundreds of thousands of single nucleotide polymorphisms (SNPs). We develop an improved multi-locus bootstrap point estimate and confidence interval, which accounts for both ranking- and threshold-selection bias in the presence of genome-wide SNP linkage disequilibrium structure. The bootstrap method easily adapts to various study designs and alternative test statistics as well as complex SNP selection criteria. The latter is demonstrated by our application to the Wellcome Trust Case Control Consortium findings, in which the selection criterion was the minimum of the p-values for the additive and genotypic genetic effect models. In contrast, existing likelihood-based bias-reduced estimators account for the selection criterion applied to an SNP as if it were the only one tested, and so are more simple computationally, but do not address ranking across SNPs. Our simulation studies show that the bootstrap bias-reduced estimates are usually closer to the true genetic effect than the likelihood estimates and are less variable with a narrower confidence interval. Replication study sample size requirements computed from the bootstrap bias-reduced estimates are adequate 75-90 per cent of the time compared to 53-60 per cent of the time for the likelihood method. The bootstrap methods are implemented in a user-friendly package able to provide point and interval estimation for both binary and quantitative phenotypes in large-scale GWAS.

  8. Descending control of neural bias and selectivity in a spatial attention network: rules and mechanisms.

    PubMed

    Mysore, Shreesh P; Knudsen, Eric I

    2014-10-01

    The brain integrates stimulus-driven (exogenous) activity with internally generated (endogenous) activity to compute the highest priority stimulus for gaze and attention. Little is known about how this computation is accomplished neurally. We explored the underlying functional logic in a critical component of the spatial attention network, the optic tectum (OT, superior colliculus in mammals), in awake barn owls. We found that space-specific endogenous influences, evoked by activating descending forebrain pathways, bias competition among exogenous influences, and substantially enhance the quality of the categorical neural pointer to the highest priority stimulus. These endogenous influences operate across sensory modalities. Biologically grounded modeling revealed that the observed effects on network bias and selectivity require a simple circuit mechanism: endogenously driven gain modulation of feedback inhibition among competing channels. Our findings reveal fundamental principles by which internal and external information combine to guide selection of the next target for gaze and attention.

  9. Descending control of neural bias and selectivity in a spatial attention network: rules and mechanisms

    PubMed Central

    Mysore, Shreesh P.; Knudsen, Eric I.

    2014-01-01

    SUMMARY The brain integrates stimulus-driven (exogenous) activity with internally generated (endogenous) activity to compute the highest priority stimulus for gaze and attention. Little is known about how this computation is accomplished neurally. We explored the underlying functional logic in a critical component of the spatial attention network, the optic tectum (OT, superior colliculus in mammals), in awake barn owls. We found that space-specific endogenous influences, evoked by activating descending forebrain pathways, bias competition among exogenous influences, and substantially enhance the quality of the categorical neural pointer to the highest priority stimulus. These endogenous influences operate across sensory modalities. Biologically grounded modeling revealed that the observed effects on network bias and selectivity require a simple circuit mechanism: endogenously driven gain modulation of feedback inhibition among competing channels. Our findings reveal fundamental principles by which internal and external information combine to guide selection of the next target for gaze and attention. PMID:25220813

  10. Evaluation of Selection Bias in an Internet-based Study of Pregnancy Planners

    PubMed Central

    Hatch, Elizabeth E.; Hahn, Kristen A.; Wise, Lauren A.; Mikkelsen, Ellen M.; Kumar, Ramya; Fox, Matthew P.; Brooks, Daniel R.; Riis, Anders H.; Sorensen, Henrik Toft; Rothman, Kenneth J.

    2016-01-01

    Selection bias is a potential concern in all epidemiologic studies, but it is usually difficult to assess. Recently, concerns have been raised that internet-based prospective cohort studies may be particularly prone to selection bias. Although use of the internet is efficient and facilitates recruitment of subjects that are otherwise difficult to enroll, any compromise in internal validity would be of great concern. Few studies have evaluated selection bias in internet-based prospective cohort studies. Using data from the Danish Medical Birth Registry from 2008 to 2012, we compared six well-known perinatal associations (e.g., smoking and birth weight) in an inter-net-based preconception cohort (Snart Gravid n = 4,801) with the total population of singleton live births in the registry (n = 239,791). We used log-binomial models to estimate risk ratios (RRs) and 95% confidence intervals (CIs) for each association. We found that most results in both populations were very similar. For example, maternal obesity was associated with an increased risk of delivering a macrosomic infant in Snart Gravid (RR = 1.5; 95% CI: 1.2, 1.7) and the total population (RR = 1.5; 95% CI: 1.45, 1.53), and maternal smoking of >10 cigarettes per day was associated with a higher risk of low birth weight (RR = 2.7; 95% CI: 1.2, 5.9 vs. RR = 2.9; 95% CI: 2.6, 3.1) in Snart Gravid and the total population, respectively. We cannot be certain that our results would apply to other associations or different populations. Nevertheless, our results suggest that recruitment of reproductive aged women via the internet may be no more prone to selection bias than traditional methods of recruitment. PMID:26484423

  11. Evaluation of Selection Bias in an Internet-based Study of Pregnancy Planners.

    PubMed

    Hatch, Elizabeth E; Hahn, Kristen A; Wise, Lauren A; Mikkelsen, Ellen M; Kumar, Ramya; Fox, Matthew P; Brooks, Daniel R; Riis, Anders H; Sorensen, Henrik Toft; Rothman, Kenneth J

    2016-01-01

    Selection bias is a potential concern in all epidemiologic studies, but it is usually difficult to assess. Recently, concerns have been raised that internet-based prospective cohort studies may be particularly prone to selection bias. Although use of the internet is efficient and facilitates recruitment of subjects that are otherwise difficult to enroll, any compromise in internal validity would be of great concern. Few studies have evaluated selection bias in internet-based prospective cohort studies. Using data from the Danish Medical Birth Registry from 2008 to 2012, we compared six well-known perinatal associations (e.g., smoking and birth weight) in an internet-based preconception cohort (Snart Gravid n = 4,801) with the total population of singleton live births in the registry (n = 239,791). We used log-binomial models to estimate risk ratios (RRs) and 95% confidence intervals (CIs) for each association. We found that most results in both populations were very similar. For example, maternal obesity was associated with an increased risk of delivering a macrosomic infant in Snart Gravid (RR = 1.5; 95% CI: 1.2, 1.7) and the total population (RR = 1.5; 95% CI: 1.45, 1.53), and maternal smoking of >10 cigarettes per day was associated with a higher risk of low birth weight (RR = 2.7; 95% CI: 1.2, 5.9 vs. RR = 2.9; 95% CI: 2.6, 3.1) in Snart Gravid and the total population, respectively. We cannot be certain that our results would apply to other associations or different populations. Nevertheless, our results suggest that recruitment of reproductive aged women via the internet may be no more prone to selection bias than traditional methods of recruitment.

  12. Observational selection biases in time-delay strong lensing and their impact on cosmography

    NASA Astrophysics Data System (ADS)

    Collett, Thomas E.; Cunnington, Steven D.

    2016-11-01

    Inferring cosmological parameters from time-delay strong lenses requires a significant investment of telescope time; it is therefore tempting to focus on the systems with the brightest sources, the highest image multiplicities and the widest image separations. We investigate if this selection bias can influence the properties of the lenses studied and the cosmological parameters inferred. Using an ellipsoidal power-law deflector population, we build a sample of double- and quadruple-image systems. Assuming reasonable thresholds on image separation and flux, based on current lens monitoring campaigns, we find that the typical density profile slopes of monitorable lenses are significantly shallower than the input ensemble. From a sample of quads, we find that this selection function can introduce a 3.5 per cent bias on the inferred time-delay distances if the properties of the input ensemble are (incorrectly) used as priors on the lens model. This bias remains at the 2.4 per cent level when high-resolution imaging of the quasar host is used to precisely infer the properties of individual lenses. We also investigate if the lines of sight for monitorable strong lenses are biased. The expectation value for the line-of-sight convergence is increased by 0.009 (0.004) for quads (doubles) implying a 0.9 per cent (0.4 per cent) bias on H0. We therefore conclude that whilst the properties of typical quasar lenses and their lines of sight do deviate from the global population, the total magnitude of this effect is likely to be a subdominant effect for current analyses, but has the potential to be a major systematic for samples of ˜25 or more lenses.

  13. The Evolution of Male-Biased Dispersal under the Joint Selective Forces of Inbreeding Load and Demographic and Environmental Stochasticity.

    PubMed

    Henry, Roslyn C; Coulon, Aurélie; Travis, Justin M J

    2016-10-01

    Sex-biased natal dispersal is widespread, and its significance remains a central question in evolutionary biology. However, theory so far fails to predict some of the most common patterns found in nature. To address this, we present novel results from an individual-based model investigating the joint roles of inbreeding load, demographic stochasticity, environmental stochasticity, and dispersal costs for the evolution of sex-biased dispersal. Most strikingly, we found that male-biased natal dispersal evolved in polygynous systems as a result of the interplay between inbreeding avoidance and stochasticity, whereas previous theory, in contrast to empirical observations, predicted male philopatry and female-biased natal dispersal under inbreeding load alone. Furthermore, the direction of the bias varied according to the nature of stochasticity. Our results therefore provide a unification of previous theory, yielding a much better qualitative match with empirical observations of male-biased dispersal in mate defense mating systems. PMID:27622876

  14. A selection model for accounting for publication bias in a full network meta-analysis.

    PubMed

    Mavridis, Dimitris; Welton, Nicky J; Sutton, Alex; Salanti, Georgia

    2014-12-30

    Copas and Shi suggested a selection model to explore the potential impact of publication bias via sensitivity analysis based on assumptions for the probability of publication of trials conditional on the precision of their results. Chootrakool et al. extended this model to three-arm trials but did not fully account for the implications of the consistency assumption, and their model is difficult to generalize for complex network structures with more than three treatments. Fitting these selection models within a frequentist setting requires maximization of a complex likelihood function, and identification problems are common. We have previously presented a Bayesian implementation of the selection model when multiple treatments are compared with a common reference treatment. We now present a general model suitable for complex, full network meta-analysis that accounts for consistency when adjusting results for publication bias. We developed a design-by-treatment selection model to describe the mechanism by which studies with different designs (sets of treatments compared in a trial) and precision may be selected for publication. We fit the model in a Bayesian setting because it avoids the numerical problems encountered in the frequentist setting, it is generalizable with respect to the number of treatments and study arms, and it provides a flexible framework for sensitivity analysis using external knowledge. Our model accounts for the additional uncertainty arising from publication bias more successfully compared to the standard Copas model or its previous extensions. We illustrate the methodology using a published triangular network for the failure of vascular graft or arterial patency.

  15. Codon usage in highly expressed genes of Haemophillus influenzae and Mycobacterium tuberculosis: translational selection versus mutational bias.

    PubMed

    Pan, A; Dutta, C; Das, J

    1998-07-30

    Biases in the codon usage and base compositions at three codon sites in different genes of A+T-rich Gram-negative bacterium Haemophillus influenzae and G+C-rich Gram-positive bacterium Mycobacterium tuberculosis have been examined to address the following questions: (1) whether the synonymous codon usage in organisms having highly skewed base compositions is totally dictated by the mutational bias as reported previously (Sharp, P.M., Devine, K.M., 1989. Codon usage and gene expression level in Dictyostelium discoideum: highly expressed genes do 'prefer' optimal codons. Nucleic Acids Res. 17, 5029-5039), or is also controlled by translational selection; (2) whether preference of G in the first codon positions by highly expressed genes, as reported in Escherichia coli (Gutierrez, G., Marquez, L., Marin, A., 1996. Preference for guanosine at first codon position in highly expressed Escherichia coli genes. A relationship with translational efficiency. Nucleic Acids Res. 24, 2525-2527), is true in other bacteria; and (3) whether the usage of bases in three codon positions is species-specific. Result presented here show that even in organisms with high mutational bias, translational selection plays an important role in dictating the synonymous codon usage, though the set of optimal codons is chosen in accordance with the mutational pressure. The frequencies of G-starting codons are positively correlated to the level of expression of genes, as estimated by their Codon Adaptation Index (CAI) values, in M. tuberculosis as well as in H. influenzae in spite of having an A+T-rich genome. The present study on the codon preferences of two organisms with oppositely skewed base compositions thus suggests that the preference of G-starting codons by highly expressed genes might be a general feature of bacteria, irrespective of their overall G+C contents. The ranges of variations in the frequencies of individual bases at the first and second codon positions of genes of both H

  16. Agonistic aptamer to the insulin receptor leads to biased signaling and functional selectivity through allosteric modulation.

    PubMed

    Yunn, Na-Oh; Koh, Ara; Han, Seungmin; Lim, Jong Hun; Park, Sehoon; Lee, Jiyoun; Kim, Eui; Jang, Sung Key; Berggren, Per-Olof; Ryu, Sung Ho

    2015-09-18

    Due to their high affinity and specificity, aptamers have been widely used as effective inhibitors in clinical applications. However, the ability to activate protein function through aptamer-protein interaction has not been well-elucidated. To investigate their potential as target-specific agonists, we used SELEX to generate aptamers to the insulin receptor (IR) and identified an agonistic aptamer named IR-A48 that specifically binds to IR, but not to IGF-1 receptor. Despite its capacity to stimulate IR autophosphorylation, similar to insulin, we found that IR-A48 not only binds to an allosteric site distinct from the insulin binding site, but also preferentially induces Y1150 phosphorylation in the IR kinase domain. Moreover, Y1150-biased phosphorylation induced by IR-A48 selectively activates specific signaling pathways downstream of IR. In contrast to insulin-mediated activation of IR, IR-A48 binding has little effect on the MAPK pathway and proliferation of cancer cells. Instead, AKT S473 phosphorylation is highly stimulated by IR-A48, resulting in increased glucose uptake both in vitro and in vivo. Here, we present IR-A48 as a biased agonist able to selectively induce the metabolic activity of IR through allosteric binding. Furthermore, our study also suggests that aptamers can be a promising tool for developing artificial biased agonists to targeted receptors. PMID:26245346

  17. Center or side: biases in selecting grasp points on small bars.

    PubMed

    Paulun, Vivian C; Kleinholdermann, Urs; Gegenfurtner, Karl R; Smeets, Jeroen B J; Brenner, Eli

    2014-07-01

    Choosing appropriate grasp points is necessary for successfully interacting with objects in our environment. We brought two possible determinants of grasp point selection into conflict: the attempt to grasp an object near its center of mass to minimize torque and ensure stability and the attempt to minimize movement distance. We let our participants grasp two elongated objects of different mass and surface friction that were approached from different distances to both sides of the object. Maximizing stability predicts grasp points close to the object's center, while minimizing movement costs predicts a bias of the grasp axis toward the side at which the movement started. We found smaller deviations from the center of mass for the smooth and heavy object, presumably because the larger torques and more slippery surface for the heavy object increase the chance of unwanted object rotation. However, our right-handed participants tended to grasp the objects to the right of the center of mass, irrespective of where the movement started. The rightward bias persisted when vision was removed once the hand was half way to the object. It was reduced when the required precision was increased. Starting the movement above the object eliminated the bias. Grasping with the left hand, participants tended to grasp the object to the left of its center. Thus, the selected grasp points seem to reflect a compromise between maximizing stability by grasping near the center of mass and grasping on the side of the acting hand, perhaps to increase visibility of the object.

  18. Mutation and Selection Cause Codon Usage and Bias in Mitochondrial Genomes of Ribbon Worms (Nemertea)

    PubMed Central

    Chen, Haixia; Sun, Shichun; Norenburg, Jon L.; Sundberg, Per

    2014-01-01

    The phenomenon of codon usage bias is known to exist in many genomes and it is mainly determined by mutation and selection. To understand the patterns of codon usage in nemertean mitochondrial genomes, we use bioinformatic approaches to analyze the protein-coding sequences of eight nemertean species. Neutrality analysis did not find a significant correlation between GC12 and GC3. ENc-plot showed a few genes on or close to the expected curve, but the majority of points with low-ENc values are below it. ENc-plot suggested that mutational bias plays a major role in shaping codon usage. The Parity Rule 2 plot (PR2) analysis showed that GC and AT were not used proportionally and we propose that codons containing A or U at third position are used preferentially in nemertean species, regardless of whether corresponding tRNAs are encoded in the mitochondrial DNA. Context-dependent analysis indicated that the nucleotide at the second codon position slightly affects synonymous codon choices. These results suggested that mutational and selection forces are probably acting to codon usage bias in nemertean mitochondrial genomes. PMID:24454907

  19. Mutation and selection cause codon usage and bias in mitochondrial genomes of ribbon worms (Nemertea).

    PubMed

    Chen, Haixia; Sun, Shichun; Norenburg, Jon L; Sundberg, Per

    2014-01-01

    The phenomenon of codon usage bias is known to exist in many genomes and it is mainly determined by mutation and selection. To understand the patterns of codon usage in nemertean mitochondrial genomes, we use bioinformatic approaches to analyze the protein-coding sequences of eight nemertean species. Neutrality analysis did not find a significant correlation between GC12 and GC3. ENc-plot showed a few genes on or close to the expected curve, but the majority of points with low-ENc values are below it. ENc-plot suggested that mutational bias plays a major role in shaping codon usage. The Parity Rule 2 plot (PR2) analysis showed that GC and AT were not used proportionally and we propose that codons containing A or U at third position are used preferentially in nemertean species, regardless of whether corresponding tRNAs are encoded in the mitochondrial DNA. Context-dependent analysis indicated that the nucleotide at the second codon position slightly affects synonymous codon choices. These results suggested that mutational and selection forces are probably acting to codon usage bias in nemertean mitochondrial genomes.

  20. Selection biases in the gamma-ray burst Eiso - Lopt, X correlation

    NASA Astrophysics Data System (ADS)

    Coward, D. M.; Howell, E. J.; Wan, L.; Macpherson, D.

    2015-04-01

    Gamma-ray burst (GRB) optical and X-ray afterglow luminosity is expected to correlate with the GRB isotropic equivalent kinetic energy of the outflow in the standard synchrotron model for GRB afterglows. Previous studies, using prompt GRB isotropic equivalent energy (Eiso) as a proxy for isotropic equivalent kinetic energy, have generally confirmed a correlation between X-ray and optical afterglow luminosities. Assuming that GRB afterglow luminosity does not evolve strongly with redshift, we identify a strong Malmquist bias in GRB optical and X-ray afterglow luminosity data. We show that selection effects dominate the observed Eiso-Lopt, X correlations, and have likely been underestimated in other studies. The bias is strongest for a subset of optically faint bursts m > 24 at 24 h with z > 2. After removing this optical selection bias, the Eiso-Lopt, X correlation for long GRBs is not statistically significant, but combining both long and short GRB luminosity data the correlation is significant. Using the median of the Eiso and Lopt, X distributions, we apply the synchrotron model assuming the same power-law index for short and long GRBs, but different microphysical parameter distributions. Comparing the ratio of optical and X-ray luminosities, we find tentative evidence that the fraction of post-shock energy in magnetic fields, ɛB, could be systematically higher in short GRBs compared to long GRBs.

  1. Are phonological influences on lexical (mis)selection the result of a monitoring bias?

    PubMed Central

    Ratinckx, Elie; Ferreira, Victor S.; Hartsuiker, Robert J.

    2009-01-01

    A monitoring bias account is often used to explain speech error patterns that seem to be the result of an interactive language production system, like phonological influences on lexical selection errors. A biased monitor is suggested to detect and covertly correct certain errors more often than others. For instance, this account predicts that errors which are phonologically similar to intended words are harder to detect than ones that are phonologically dissimilar. To test this, we tried to elicit phonological errors under the same conditions that show other kinds of lexical selection errors. In five experiments, we presented participants with high cloze probability sentence fragments followed by a picture that was either semantically related, a homophone of a semantically related word, or phonologically related to the (implicit) last word of the sentence. All experiments elicited semantic completions or homophones of semantic completions, but none elicited phonological completions. This finding is hard to reconcile with a monitoring bias account and is better explained with an interactive production system. Additionally, this finding constrains the amount of bottom-up information flow in interactive models. PMID:18942035

  2. Agonistic aptamer to the insulin receptor leads to biased signaling and functional selectivity through allosteric modulation

    PubMed Central

    Yunn, Na-Oh; Koh, Ara; Han, Seungmin; Lim, Jong Hun; Park, Sehoon; Lee, Jiyoun; Kim, Eui; Jang, Sung Key; Berggren, Per-Olof; Ryu, Sung Ho

    2015-01-01

    Due to their high affinity and specificity, aptamers have been widely used as effective inhibitors in clinical applications. However, the ability to activate protein function through aptamer-protein interaction has not been well-elucidated. To investigate their potential as target-specific agonists, we used SELEX to generate aptamers to the insulin receptor (IR) and identified an agonistic aptamer named IR-A48 that specifically binds to IR, but not to IGF-1 receptor. Despite its capacity to stimulate IR autophosphorylation, similar to insulin, we found that IR-A48 not only binds to an allosteric site distinct from the insulin binding site, but also preferentially induces Y1150 phosphorylation in the IR kinase domain. Moreover, Y1150-biased phosphorylation induced by IR-A48 selectively activates specific signaling pathways downstream of IR. In contrast to insulin-mediated activation of IR, IR-A48 binding has little effect on the MAPK pathway and proliferation of cancer cells. Instead, AKT S473 phosphorylation is highly stimulated by IR-A48, resulting in increased glucose uptake both in vitro and in vivo. Here, we present IR-A48 as a biased agonist able to selectively induce the metabolic activity of IR through allosteric binding. Furthermore, our study also suggests that aptamers can be a promising tool for developing artificial biased agonists to targeted receptors. PMID:26245346

  3. Selection bias in dynamically measured supermassive black hole samples: consequences for pulsar timing arrays

    NASA Astrophysics Data System (ADS)

    Sesana, Alberto; Shankar, Francesco; Bernardi, Mariangela; Sheth, Ravi K.

    2016-11-01

    Supermassive black hole -- host galaxy relations are key to the computation of the expected gravitational wave background (GWB) in the pulsar timing array (PTA) frequency band. It has been recently pointed out that standard relations adopted in GWB computations are in fact biased-high. We show that when this selection bias is taken into account, the expected GWB in the PTA band is a factor of about three smaller than previously estimated. Compared to other scaling relations recently published in the literature, the median amplitude of the signal at $f=1$yr$^{-1}$ drops from $1.3\\times10^{-15}$ to $4\\times10^{-16}$. Although this solves any potential tension between theoretical predictions and recent PTA limits without invoking other dynamical effects (such as stalling, eccentricity or strong coupling with the galactic environment), it also makes the GWB detection more challenging.

  4. Disentangling mode-specific selection and measurement bias in social surveys.

    PubMed

    Schouten, Barry; van den Brakel, Jan; Buelens, Bart; van der Laan, Jan; Klausch, Thomas

    2013-11-01

    A large-scale mixed-mode experiment linked to the Dutch Crime Victimization Survey was conducted in 2011. The experiment consisted of two waves; one wave with random assignment to one of the modes web, paper, telephone and face-to-face, and one follow-up wave to the full sample with interviewer modes only. The objective of the experiment is to estimate total mode effects and more specifically the corresponding mode effect components arising from undercoverage, nonresponse and measurement. In this paper, mode-specific selection and measurement bias are defined, and estimators for the bias terms based on the experimental design are introduced and discussed. The proposed estimators are applied to a number of key survey variables from the Labour Force Survey and the Crime Victimization Survey.

  5. Intron evolution in Neurospora: the role of mutational bias and selection.

    PubMed

    Sun, Yu; Whittle, Carrie A; Corcoran, Pádraic; Johannesson, Hanna

    2015-01-01

    We used comparative and population genomics to study intron evolutionary dynamics in the fungal model genus Neurospora. For our investigation, we used well-annotated genomes of N. crassa, N. discreta, and N. tetrasperma, and 92 resequenced genomes of N. tetrasperma from natural populations. By analyzing the four well-annotated genomes, we identified 9495 intron sites in 7619 orthologous genes. Our data supports nonhomologous end joining (NHEJ) and tandem duplication as mechanisms for intron gains in the genus and the RT-mRNA process as a mechanism for intron loss. We found a moderate intron gain rate (5.78-6.89 × 10(-13) intron gains per nucleotide site per year) and a high intron loss rate (7.53-13.76 × 10(-10) intron losses per intron sites per year) as compared to other eukaryotes. The derived intron gains and losses are skewed to high frequencies, relative to neutral SNPs, in natural populations of N. tetrasperma, suggesting that selection is involved in maintaining a high intron turnover. Furthermore, our analyses of the association between intron population-level frequency and genomic features suggest that selection is involved in shaping a 5' intron position bias and a low intron GC content. However, intron sequence analyses suggest that the gained introns were not exposed to recent selective sweeps. Taken together, this work contributes to our understanding of the importance of mutational bias and selection in shaping the intron distribution in eukaryotic genomes.

  6. Exploring the influential factors in incident clearance time: Disentangling causation from self-selection bias.

    PubMed

    Ding, Chuan; Ma, Xiaolei; Wang, Yinhai; Wang, Yunpeng

    2015-12-01

    Understanding the relationships between influential factors and incident clearance time is crucial to make effective countermeasures for incident management agencies. Although there have been a certain number of achievements on incident clearance time modeling, limited effort is made to investigate the relative role of incident response time and its self-selection in influencing the clearance time. To fill this gap, this study uses the endogenous switching model to explore the influential factors in incident clearance time, and aims to disentangle causation from self-selection bias caused by response process. Under the joint two-stage model framework, the binary probit model and switching regression model are formulated for both incident response time and clearance time, respectively. Based on the freeway incident data collected in Washington State, full information maximum likelihood (FIML) method is utilized to estimate the endogenous switching model parameters. Significant factors affecting incident response time and clearance time can be identified, including incident, temporal, geographical, environmental, traffic and operational attributes. The estimate results reveal the influential effects of incident, temporal, geographical, environmental, traffic and operational factors on incident response time and clearance time. In addition, the causality of incident response time itself and its self-selection correction on incident clearance time are found to be indispensable. These findings suggest that the causal effect of response time on incident clearance time will be overestimated if the self-selection bias is not considered.

  7. Exploring the influential factors in incident clearance time: Disentangling causation from self-selection bias.

    PubMed

    Ding, Chuan; Ma, Xiaolei; Wang, Yinhai; Wang, Yunpeng

    2015-12-01

    Understanding the relationships between influential factors and incident clearance time is crucial to make effective countermeasures for incident management agencies. Although there have been a certain number of achievements on incident clearance time modeling, limited effort is made to investigate the relative role of incident response time and its self-selection in influencing the clearance time. To fill this gap, this study uses the endogenous switching model to explore the influential factors in incident clearance time, and aims to disentangle causation from self-selection bias caused by response process. Under the joint two-stage model framework, the binary probit model and switching regression model are formulated for both incident response time and clearance time, respectively. Based on the freeway incident data collected in Washington State, full information maximum likelihood (FIML) method is utilized to estimate the endogenous switching model parameters. Significant factors affecting incident response time and clearance time can be identified, including incident, temporal, geographical, environmental, traffic and operational attributes. The estimate results reveal the influential effects of incident, temporal, geographical, environmental, traffic and operational factors on incident response time and clearance time. In addition, the causality of incident response time itself and its self-selection correction on incident clearance time are found to be indispensable. These findings suggest that the causal effect of response time on incident clearance time will be overestimated if the self-selection bias is not considered. PMID:26373988

  8. Sexual selection and trichromatic color vision in primates: statistical support for the preexisting-bias hypothesis.

    PubMed

    Fernandez, Andre A; Morris, Molly R

    2007-07-01

    The evolution of trichromatic color vision in primates may improve foraging performance as well as intraspecific communication; however, the context in which color vision initially evolved is unknown. We statistically examined the hypothesis that trichromatic color vision in primates represents a preexisting bias for the evolution of red coloration (pelage and/or skin) through sexual selection. Our analyses show that trichromatic color vision evolved before red pelage and red skin, as well as before gregarious mating systems that would promote sexual selection for visual traits and other forms of intraspecific communication via red traits. We also determined that both red pelage and red skin were more likely to evolve in the presence of color vision and mating systems that promote sexual selection. These results provide statistical support for the hypothesis that trichromatic color vision in primates evolved in a context other than intraspecific communication with red traits, most likely foraging performance, but, once evolved, represented a preexisting bias that promoted the evolution of red traits through sexual selection.

  9. ACTIVE LEARNING TO OVERCOME SAMPLE SELECTION BIAS: APPLICATION TO PHOTOMETRIC VARIABLE STAR CLASSIFICATION

    SciTech Connect

    Richards, Joseph W.; Starr, Dan L.; Miller, Adam A.; Bloom, Joshua S.; Butler, Nathaniel R.; Berian James, J.; Brink, Henrik; Long, James P.; Rice, John

    2012-01-10

    Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data often manifest as strongly biased predictions on the data of interest. Typically, training sets are derived from historical surveys of brighter, more nearby objects than those from more extensive, deeper surveys (testing data). This sample selection bias can cause catastrophic errors in predictions on the testing data because (1) standard assumptions for machine-learned model selection procedures break down and (2) dense regions of testing space might be completely devoid of training data. We explore possible remedies to sample selection bias, including importance weighting, co-training, and active learning (AL). We argue that AL-where the data whose inclusion in the training set would most improve predictions on the testing set are queried for manual follow-up-is an effective approach and is appropriate for many astronomical applications. For a variable star classification problem on a well-studied set of stars from Hipparcos and Optical Gravitational Lensing Experiment, AL is the optimal method in terms of error rate on the testing data, beating the off-the-shelf classifier by 3.4% and the other proposed methods by at least 3.0%. To aid with manual labeling of variable stars, we developed a Web interface which allows for easy light curve visualization and querying of external databases. Finally, we apply AL to classify variable stars in the All Sky Automated Survey, finding dramatic improvement in our agreement with the ASAS Catalog of Variable Stars, from 65.5% to 79.5%, and a significant increase in the classifier's average confidence for the testing set, from 14.6% to 42.9%, after a few AL iterations.

  10. Case-control studies in clinical research: mechanism and prevention of selection bias.

    PubMed

    Morabia, A

    1997-01-01

    The mechanism by which selection bias occurs in case-control studies is explained to an audience of clinicians using a simple conceptual framework and a graphical presentation. A case-control study consists in comparing the frequency of exposure in a group of subjects having the studied disease (the cases) relative to another group free of that disease (the controls). Cases and controls can be thought of as arising from a hypothetical cohort study. Thus, enrolled cases are a fraction F1 of the exposed who developed the disease plus a fraction F3 of the unexposed who developed the disease during a given period. Similarly, enrolled controls are a fraction F2 of the exposed who did not develop disease plus a fraction F4 of the unexposed who did not develop the disease. A selection process is inherent to the design of case-control studies but it leads to selection bias only when the ratio of F1 x F4/F2 x F3 is not equal to unity. Examples demonstrate the implication of sampling fractions for designing and interpreting case-control studies performed in clinical settings.

  11. Potential unsatisfiability of cyclic constraints on stochastic biological networks biases selection towards hierarchical architectures

    PubMed Central

    Smith, Cameron; Pechuan, Ximo; Puzio, Raymond S.; Biro, Daniel; Bergman, Aviv

    2015-01-01

    Constraints placed upon the phenotypes of organisms result from their interactions with the environment. Over evolutionary time scales, these constraints feed back onto smaller molecular subnetworks comprising the organism. The evolution of biological networks is studied by considering a network of a few nodes embedded in a larger context. Taking into account this fact that any network under study is actually embedded in a larger context, we define network architecture, not on the basis of physical interactions alone, but rather as a specification of the manner in which constraints are placed upon the states of its nodes. We show that such network architectures possessing cycles in their topology, in contrast to those that do not, may be subjected to unsatisfiable constraints. This may be a significant factor leading to selection biased against those network architectures where such inconsistent constraints are more likely to arise. We proceed to quantify the likelihood of inconsistency arising as a function of network architecture finding that, in the absence of sampling bias over the space of possible constraints and for a given network size, networks with a larger number of cycles are more likely to have unsatisfiable constraints placed upon them. Our results identify a constraint that, at least in isolation, would contribute to a bias in the evolutionary process towards more hierarchical -modular versus completely connected network architectures. Together, these results highlight the context dependence of the functionality of biological networks. PMID:26040595

  12. The interaction between developmental bias and natural selection: from centipede segments to a general hypothesis.

    PubMed

    Arthur, W

    2002-10-01

    Do limitations to the ways in which mutations can alter developmental processes help to determine the direction of phenotypic evolution? In the early days of neo-Darwinism, the answer given to this question was an emphatic 'no'. However, recent work, both theoretical and empirical, argues that the answer should at least be 'sometimes', and possibly even a straightforward 'yes'. Here, I examine the key concept of developmental bias, which encompasses both developmental constraint and developmental drive. I review the case of centipede segment number, which is a particularly clear example of developmental bias, but also a rather unusual one. I then consider how, in general terms, developmental bias and natural selection might interact, with the result that it is their interaction, rather than either process on its own, that determines evolutionary direction. Essentially, the whole argument is about the extent to which phenotypic variation is developmentally structured as opposed to amorphous or random. This issue can be traced back to the very beginning of evolutionary biology, and in particular to a difference of opinion between Darwin and Wallace, who emphasized, respectively, character correlation and character independence.

  13. Geographic selection bias of occurrence data influences transferability of invasive Hydrilla verticillata distribution models

    PubMed Central

    Barnes, Matthew A; Jerde, Christopher L; Wittmann, Marion E; Chadderton, W Lindsay; Ding, Jianqing; Zhang, Jialiang; Purcell, Matthew; Budhathoki, Milan; Lodge, David M

    2014-01-01

    Due to socioeconomic differences, the accuracy and extent of reporting on the occurrence of native species differs among countries, which can impact the performance of species distribution models. We assessed the importance of geographical biases in occurrence data on model performance using Hydrilla verticillata as a case study. We used Maxent to predict potential North American distribution of the aquatic invasive macrophyte based upon training data from its native range. We produced a model using all available native range occurrence data, then explored the change in model performance produced by omitting subsets of training data based on political boundaries. We also compared those results with models trained on data from which a random sample of occurrence data was omitted from across the native range. Although most models accurately predicted the occurrence of H. verticillata in North America (AUC > 0.7600), data omissions influenced model predictions. Omitting data based on political boundaries resulted in larger shifts in model accuracy than omitting randomly selected occurrence data. For well-documented species like H. verticillata, missing records from single countries or ecoregions may minimally influence model predictions, but for species with fewer documented occurrences or poorly understood ranges, geographic biases could misguide predictions. Regardless of focal species, we recommend that future species distribution modeling efforts begin with a reflection on potential spatial biases of available occurrence data. Improved biodiversity surveillance and reporting will provide benefit not only in invaded ranges but also within under-reported and unexplored native ranges. PMID:25360288

  14. Autocrine selection of a GLP-1R G-protein biased agonist with potent antidiabetic effects

    PubMed Central

    Zhang, Hongkai; Sturchler, Emmanuel; Zhu, Jiang; Nieto, Ainhoa; Cistrone, Philip A.; Xie, Jia; He, LinLing; Yea, Kyungmoo; Jones, Teresa; Turn, Rachel; Di Stefano, Peter S.; Griffin, Patrick R.; Dawson, Philip E.; McDonald, Patricia H.; Lerner, Richard A.

    2015-01-01

    Glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) agonists have emerged as treatment options for type 2 diabetes mellitus (T2DM). GLP-1R signals through G-protein-dependent, and G-protein-independent pathways by engaging the scaffold protein β-arrestin; preferential signalling of ligands through one or the other of these branches is known as ‘ligand bias'. Here we report the discovery of the potent and selective GLP-1R G-protein-biased agonist, P5. We identified P5 in a high-throughput autocrine-based screening of large combinatorial peptide libraries, and show that P5 promotes G-protein signalling comparable to GLP-1 and Exendin-4, but exhibited a significantly reduced β-arrestin response. Preclinical studies using different mouse models of T2DM demonstrate that P5 is a weak insulin secretagogue. Nevertheless, chronic treatment of diabetic mice with P5 increased adipogenesis, reduced adipose tissue inflammation as well as hepatic steatosis and was more effective at correcting hyperglycaemia and lowering haemoglobin A1c levels than Exendin-4, suggesting that GLP-1R G-protein-biased agonists may provide a novel therapeutic approach to T2DM. PMID:26621478

  15. Selection bias in species distribution models: An econometric approach on forest trees based on structural modeling

    NASA Astrophysics Data System (ADS)

    Martin-StPaul, N. K.; Ay, J. S.; Guillemot, J.; Doyen, L.; Leadley, P.

    2014-12-01

    Species distribution models (SDMs) are widely used to study and predict the outcome of global changes on species. In human dominated ecosystems the presence of a given species is the result of both its ecological suitability and human footprint on nature such as land use choices. Land use choices may thus be responsible for a selection bias in the presence/absence data used in SDM calibration. We present a structural modelling approach (i.e. based on structural equation modelling) that accounts for this selection bias. The new structural species distribution model (SSDM) estimates simultaneously land use choices and species responses to bioclimatic variables. A land use equation based on an econometric model of landowner choices was joined to an equation of species response to bioclimatic variables. SSDM allows the residuals of both equations to be dependent, taking into account the possibility of shared omitted variables and measurement errors. We provide a general description of the statistical theory and a set of applications on forest trees over France using databases of climate and forest inventory at different spatial resolution (from 2km to 8km). We also compared the outputs of the SSDM with outputs of a classical SDM (i.e. Biomod ensemble modelling) in terms of bioclimatic response curves and potential distributions under current climate and climate change scenarios. The shapes of the bioclimatic response curves and the modelled species distribution maps differed markedly between SSDM and classical SDMs, with contrasted patterns according to species and spatial resolutions. The magnitude and directions of these differences were dependent on the correlations between the errors from both equations and were highest for higher spatial resolutions. A first conclusion is that the use of classical SDMs can potentially lead to strong miss-estimation of the actual and future probability of presence modelled. Beyond this selection bias, the SSDM we propose represents

  16. Selection bias in genetic-epidemiological studies of cleft lip and palate

    SciTech Connect

    Christensen, K.; Holm, N.V.; Kock, K. ); Olsen, J. ); Fogh-Anderson, P.

    1992-09-01

    The possible impact of selection bias in genetic and epidemiological studies of cleft lip and palate was studied, using three nationwide ascertainment sources and an autopsy study in a 10% sample of the Danish population. A total of 670 cases were identified. Two national record systems, when used together, were found suitable for ascertaining facial cleft in live births. More than 95% ascertainment was obtained by means of surgical files for cleft lip (with or without cleft palate) without associated malformations/syndromes. However, surgical files could be a poor source for studying isolated cleft palate (CP) (only a 60% and biased ascertainment), and they cannot be used to study the prevalence of associated malformations or syndromes in facial cleft cases. The male:female ratio was 0.88 in surgically treated cases of CP and was 1.5 in nonoperated CP cases, making the overall sex ratio for CP 1.1 (95% confidence limits 0.86-1.4) The sex ratio for CP without associated malformation was 1.1 (95% confidence limits 0.84-1.6). One of the major test criteria in CP multifactorial threshold models (higher CP liability among male CP relatives) must be reconsidered, if other investigations confirm that a CP sex-ratio reversal to male predominance occurs when high ascertainment is achieved. 24 refs., 1 fig., 4 tabs.

  17. How evidence-based medicine is failing due to biased trials and selective publication.

    PubMed

    Every-Palmer, Susanna; Howick, Jeremy

    2014-12-01

    Evidence-based medicine (EBM) was announced in the early 1990s as a 'new paradigm' for improving patient care. Yet there is currently little evidence that EBM has achieved its aim. Since its introduction, health care costs have increased while there remains a lack of high-quality evidence suggesting EBM has resulted in substantial population-level health gains. In this paper we suggest that EBM's potential for improving patients' health care has been thwarted by bias in the choice of hypotheses tested, manipulation of study design and selective publication. Evidence for these flaws is clearest in industry-funded studies. We argue EBM's indiscriminate acceptance of industry-generated 'evidence' is akin to letting politicians count their own votes. Given that most intervention studies are industry funded, this is a serious problem for the overall evidence base. Clinical decisions based on such evidence are likely to be misinformed, with patients given less effective, harmful or more expensive treatments. More investment in independent research is urgently required. Independent bodies, informed democratically, need to set research priorities. We also propose that evidence rating schemes are formally modified so research with conflict of interest bias is explicitly downgraded in value.

  18. Bias-controlled selective excitation of vibrational modes in molecular junctions: a route towards mode-selective chemistry.

    PubMed

    Volkovich, Roie; Härtle, Rainer; Thoss, Michael; Peskin, Uri

    2011-08-28

    We show that individual vibrational modes in single-molecule junctions with asymmetric molecule-lead coupling can be selectively excited by applying an external bias voltage. Thereby, a non-statistical distribution of vibrational energy can be generated, that is, a mode with a higher frequency can be stronger excited than a mode with a lower frequency. This is of particular interest in the context of mode-selective chemistry, where one aims to break specific (not necessarily the weakest) chemical bond in a molecule. Such mode-selective vibrational excitation is demonstrated for two generic model systems representing asymmetric molecular junctions and/or scanning tunneling microscopy experiments. To this end, we employ two complementary theoretical approaches, a nonequilibrium Green's function approach and a master equation approach. The comparison of both methods reveals good agreement in describing resonant electron transport through a single-molecule contact, where differences between the approaches highlight the role of non-resonant transport processes, in particular co-tunneling and off-resonant electron-hole pair creation processes.

  19. Color-Biased Regions of the Ventral Visual Pathway Lie between Face- and Place-Selective Regions in Humans, as in Macaques

    PubMed Central

    Conway, Bevil R.; Kanwisher, Nancy G.

    2016-01-01

    The existence of color-processing regions in the human ventral visual pathway (VVP) has long been known from patient and imaging studies, but their location in the cortex relative to other regions, their selectivity for color compared with other properties (shape and object category), and their relationship to color-processing regions found in nonhuman primates remain unclear. We addressed these questions by scanning 13 subjects with fMRI while they viewed two versions of movie clips (colored, achromatic) of five different object classes (faces, scenes, bodies, objects, scrambled objects). We identified regions in each subject that were selective for color, faces, places, and object shape, and measured responses within these regions to the 10 conditions in independently acquired data. We report two key findings. First, the three previously reported color-biased regions (located within a band running posterior–anterior along the VVP, present in most of our subjects) were sandwiched between face-selective cortex and place-selective cortex, forming parallel bands of face, color, and place selectivity that tracked the fusiform gyrus/collateral sulcus. Second, the posterior color-biased regions showed little or no selectivity for object shape or for particular stimulus categories and showed no interaction of color preference with stimulus category, suggesting that they code color independently of shape or stimulus category; moreover, the shape-biased lateral occipital region showed no significant color bias. These observations mirror results in macaque inferior temporal cortex (Lafer-Sousa and Conway, 2013), and taken together, these results suggest a homology in which the entire tripartite face/color/place system of primates migrated onto the ventral surface in humans over the course of evolution. SIGNIFICANCE STATEMENT Here we report that color-biased cortex is sandwiched between face-selective and place-selective cortex on the bottom surface of the brain in humans

  20. The Difference-in-Difference Method: Assessing the Selection Bias in the Effects of Neighborhood Environment on Health

    PubMed Central

    Grafova, Irina; Freedman, Vicki; Lurie, Nicole; Kumar, Rizie; Rogowski, Jeannette

    2013-01-01

    This paper uses the difference-in-difference estimation approach to explore the self-selection bias in estimating the effect of neighborhood economic environment on self-assessed health among older adults. The results indicate that there is evidence of downward bias in the conventional estimates of the effect of neighborhood economic disadvantage on self-reported health, representing a lower bound of the true effect. PMID:23623818

  1. Selection Bias in Students' Evaluation of Teaching: Causes of Student Absenteeism and Its Consequences for Course Ratings and Rankings

    ERIC Educational Resources Information Center

    Wolbring, Tobias; Treischl, Edgar

    2016-01-01

    Systematic sampling error due to self-selection is a common topic in methodological research and a key challenge for every empirical study. Since selection bias is often not sufficiently considered as a potential flaw in research on and evaluations in higher education, the aim of this paper is to raise awareness for the topic using the case of…

  2. Equivalence between Step Selection Functions and Biased Correlated Random Walks for Statistical Inference on Animal Movement

    PubMed Central

    Duchesne, Thierry; Fortin, Daniel; Rivest, Louis-Paul

    2015-01-01

    Animal movement has a fundamental impact on population and community structure and dynamics. Biased correlated random walks (BCRW) and step selection functions (SSF) are commonly used to study movements. Because no studies have contrasted the parameters and the statistical properties of their estimators for models constructed under these two Lagrangian approaches, it remains unclear whether or not they allow for similar inference. First, we used the Weak Law of Large Numbers to demonstrate that the log-likelihood function for estimating the parameters of BCRW models can be approximated by the log-likelihood of SSFs. Second, we illustrated the link between the two approaches by fitting BCRW with maximum likelihood and with SSF to simulated movement data in virtual environments and to the trajectory of bison (Bison bison L.) trails in natural landscapes. Using simulated and empirical data, we found that the parameters of a BCRW estimated directly from maximum likelihood and by fitting an SSF were remarkably similar. Movement analysis is increasingly used as a tool for understanding the influence of landscape properties on animal distribution. In the rapidly developing field of movement ecology, management and conservation biologists must decide which method they should implement to accurately assess the determinants of animal movement. We showed that BCRW and SSF can provide similar insights into the environmental features influencing animal movements. Both techniques have advantages. BCRW has already been extended to allow for multi-state modeling. Unlike BCRW, however, SSF can be estimated using most statistical packages, it can simultaneously evaluate habitat selection and movement biases, and can easily integrate a large number of movement taxes at multiple scales. SSF thus offers a simple, yet effective, statistical technique to identify movement taxis. PMID:25898019

  3. Sex-biased dispersal, kin selection and the evolution of sexual conflict.

    PubMed

    Faria, Gonçalo S; Varela, Susana A M; Gardner, Andy

    2015-10-01

    There is growing interest in resolving the curious disconnect between the fields of kin selection and sexual selection. Rankin's (2011, J. Evol. Biol. 24, 71-81) theoretical study of the impact of kin selection on the evolution of sexual conflict in viscous populations has been particularly valuable in stimulating empirical research in this area. An important goal of that study was to understand the impact of sex-specific rates of dispersal upon the coevolution of male-harm and female-resistance behaviours. But the fitness functions derived in Rankin's study do not flow from his model's assumptions and, in particular, are not consistent with sex-biased dispersal. Here, we develop new fitness functions that do logically flow from the model's assumptions, to determine the impact of sex-specific patterns of dispersal on the evolution of sexual conflict. Although Rankin's study suggested that increasing male dispersal always promotes the evolution of male harm and that increasing female dispersal always inhibits the evolution of male harm, we find that the opposite can also be true, depending upon parameter values. PMID:26190034

  4. Potential sources of analytical bias and error in selected trace element data-quality analyses

    USGS Publications Warehouse

    Paul, Angela P.; Garbarino, John R.; Olsen, Lisa D.; Rosen, Michael R.; Mebane, Christopher A.; Struzeski, Tedmund M.

    2016-09-28

    Potential sources of analytical bias and error associated with laboratory analyses for selected trace elements where concentrations were greater in filtered samples than in paired unfiltered samples were evaluated by U.S. Geological Survey (USGS) Water Quality Specialists in collaboration with the USGS National Water Quality Laboratory (NWQL) and the Branch of Quality Systems (BQS).Causes for trace-element concentrations in filtered samples to exceed those in associated unfiltered samples have been attributed to variability in analytical measurements, analytical bias, sample contamination either in the field or laboratory, and (or) sample-matrix chemistry. These issues have not only been attributed to data generated by the USGS NWQL but have been observed in data generated by other laboratories. This study continues the evaluation of potential analytical bias and error resulting from matrix chemistry and instrument variability by evaluating the performance of seven selected trace elements in paired filtered and unfiltered surface-water and groundwater samples collected from 23 sampling sites of varying chemistries from six States, matrix spike recoveries, and standard reference materials.Filtered and unfiltered samples have been routinely analyzed on separate inductively coupled plasma-mass spectrometry instruments. Unfiltered samples are treated with hydrochloric acid (HCl) during an in-bottle digestion procedure; filtered samples are not routinely treated with HCl as part of the laboratory analytical procedure. To evaluate the influence of HCl on different sample matrices, an aliquot of the filtered samples was treated with HCl. The addition of HCl did little to differentiate the analytical results between filtered samples treated with HCl from those samples left untreated; however, there was a small, but noticeable, decrease in the number of instances where a particular trace-element concentration was greater in a filtered sample than in the associated

  5. Unilateral deactivation of macaque dorsolateral prefrontal cortex induces biases in stimulus selection.

    PubMed

    Johnston, Kevin; Lomber, Stephen G; Everling, Stefan

    2016-03-01

    Following unilateral brain injury, patients are often unable to detect a stimulus presented in the contralesional field when another is presented simultaneously ipsilesionally. This phenomenon has been referred to as extinction and has been conceptualized as a deficit in selective attention. Although most commonly observed following damage to posterior parietal areas, extinction has been observed following lesions of prefrontal cortex (PFC) in both humans and nonhuman primates. To date, most studies in nonhuman primates have examined lesions of multiple PFC subregions, including the frontal eye fields (FEF). Theoretical accounts of attentional disturbances from human patients, however, also implicate other PFC areas, including the middle frontal gyrus. Here, we investigated the effects of deactivating PFC areas anterior to the FEF on stimulus selection using a free-choice task. Macaque monkeys were presented with two peripheral stimuli appearing either simultaneously, or at varying stimulus onset asynchronies, and their performance was evaluated during unilateral cryogenic deactivation of part of dorsolateral prefrontal cortex or the cortex lining the caudal principal sulcus, the likely homologue of the human middle frontal gyrus. A decreased proportion of saccades was made to stimuli presented in the hemifield contralateral to the deactivated PFC. We also observed increases in reaction times to contralateral stimuli and decreases for stimuli presented in the hemifield ipsilateral to the deactivated hemisphere. In both cases, these results were greatest when both PFC subregions were deactivated. These findings demonstrate that selection biases result from PFC deactivation and support a role of dorsolateral prefrontal subregions anterior to FEF in stimulus selection. PMID:26792881

  6. Potential sources of analytical bias and error in selected trace element data-quality analyses

    USGS Publications Warehouse

    Paul, Angela P.; Garbarino, John R.; Olsen, Lisa D.; Rosen, Michael R.; Mebane, Christopher A.; Struzeski, Tedmund M.

    2016-09-28

    Potential sources of analytical bias and error associated with laboratory analyses for selected trace elements where concentrations were greater in filtered samples than in paired unfiltered samples were evaluated by U.S. Geological Survey (USGS) Water Quality Specialists in collaboration with the USGS National Water Quality Laboratory (NWQL) and the Branch of Quality Systems (BQS).Causes for trace-element concentrations in filtered samples to exceed those in associated unfiltered samples have been attributed to variability in analytical measurements, analytical bias, sample contamination either in the field or laboratory, and (or) sample-matrix chemistry. These issues have not only been attributed to data generated by the USGS NWQL but have been observed in data generated by other laboratories. This study continues the evaluation of potential analytical bias and error resulting from matrix chemistry and instrument variability by evaluating the performance of seven selected trace elements in paired filtered and unfiltered surface-water and groundwater samples collected from 23 sampling sites of varying chemistries from six States, matrix spike recoveries, and standard reference materials.Filtered and unfiltered samples have been routinely analyzed on separate inductively coupled plasma-mass spectrometry instruments. Unfiltered samples are treated with hydrochloric acid (HCl) during an in-bottle digestion procedure; filtered samples are not routinely treated with HCl as part of the laboratory analytical procedure. To evaluate the influence of HCl on different sample matrices, an aliquot of the filtered samples was treated with HCl. The addition of HCl did little to differentiate the analytical results between filtered samples treated with HCl from those samples left untreated; however, there was a small, but noticeable, decrease in the number of instances where a particular trace-element concentration was greater in a filtered sample than in the associated

  7. Battling the GPA Bias: Selecting NSF-REU Participants for Transformative Research Experiences

    NASA Astrophysics Data System (ADS)

    Smith, M.; Kim, C. S.; Osborn, J.

    2014-12-01

    Student grade point average (GPA) is one of the most common metrics used to select REU participants, with >85% of NSF-funded research participants nationally having an average GPA at or above 3.0 (Russell, 2004). Yet, as efforts are made to expand and diversify the pool of undergraduates participating in research experiences, privileging candidates with GPAs above 3.0 may exclude promising STEM students who can most benefit from a research experience, including community college students and recent transfer students from community colleges. Myriad factors that impinge on student GPAs are salient in the literature, including (1) early academic failure related to pre-college under-preparation (Feldman, 1993); (2) transfer shock (Molinaro, 2014; Diaz, 1992); (3) employment (DeSimone, 2008); (4) limited social support for academic pursuits (Cheng, Ickes, & Verhofstadt, 2012); (5) food insecurity (Maroto, 2013); and inadequate advising (Pascarella & Terenzini, 2005). A discussion of these factors with examples from student transcripts and an overview of a scoring rubric that minimizes GPA bias and can assist PIs with an alternate approach to participant selection will be included in this session.

  8. Untold stories: biases and selection effects in research with victims of trafficking for sexual exploitation.

    PubMed

    Brunovskis, Anette; Surtees, Rebecca

    2010-01-01

    Recent discussions of trafficking research have included calls for more innovative studies and new methodologies in order to move beyond the current trafficking narrative, which is often based on unrepresentative samples and overly simplified images. While new methods can potentially play a role in expanding the knowledge base on trafficking, this article argues that the solution is not entirely about applying new methods, but as much about using current methods to greater effect and with careful attention to their limitations and ethical constraints. Drawing on the authors' experience in researching trafficking issues in a number of projects over the past decade, the article outlines and exemplifies some of the methodological and ethical issues to be considered and accommodated when conducting research with trafficked persons -- including unrepresentative samples; access to respondents; selection biases by "gatekeepers" and self selection by potential respondents. Such considerations should inform not only how research is undertaken but also how this information is read and understood. Moreover, many of these considerations equally apply when considering the application of new methods within this field. The article maintains that a better understanding of how these issues come into play and inform trafficking research will translate into tools for conducting improved research in this field and, by implication, new perspectives on human trafficking. PMID:20645469

  9. Recurrent positive selection and heterogeneous codon usage bias events leading to coexistence of divergent pigeon circoviruses.

    PubMed

    Liao, Pei-Chun; Wang, Kung-Kai; Tsai, Shinn-Shyong; Liu, Hung-Jen; Huang, Bing-Hong; Chuang, Kuo-Pin

    2015-08-01

    The capsid genes from 14 pigeon circovirus (PiCV) sequences, collected from Taiwan between 2009 and 2010, were sequenced and compared with 14 PiCV capsid gene sequences from GenBank. Based on pairwise comparison, PiCV strains from Taiwan shared 73.9-100% nucleotide identity and 72-100% amino acid identity with those of the 14 reported PiCV sequences. Phylogenetic analyses revealed that Taiwanese PiCV isolates can be grouped into two clades: clade 1 comprising isolates from Belgium, Australia, USA, Italy and China, and clade 2 showing close relation to isolates from Germany and France. Recurrent positive selection was detected in clade 1 PiCV lineages, which may contribute to the diversification of predominant PiCV sequences in Taiwan. Further observations suggest that synonymous codon usage variations between PiCV clade 1 and clade 2 may reflect the adaptive divergence on translation efficiency of capsid genes in infectious hosts. Variation in selective pressures acting on the evolutionary divergence and codon usage bias of both clades explains the regional coexistence of virus sequences congeners prevented from competitive exclusion within an island such as Taiwan. Our genotyping results also provide insight into the aetiological agents of PiCV outbreak in Taiwan and we present a comparative analysis of the central coding region of PiCV genome. From the sequence comparison results of 28 PiCVs which differs in regard to the geographical origin and columbid species, we identified conserved regions within the capsid gene that are likely to be suitable for primer selection and vaccine development.

  10. The Body Mass Index-Mortality Link across the Life Course: Two Selection Biases and Their Effects

    PubMed Central

    Zheng, Hui; Dirlam, Jonathan

    2016-01-01

    In this study, we investigated two selection biases that may affect the obesity-mortality link over the life course: mortality selection and healthy participant effects. If these selection mechanisms are stronger among obese adults than among non-obese adults, they may contribute to the weakening obesity-mortality link over the life course. We used data from the National Health and Nutrition Examination Survey 1988–2010 with linked mortality files from 1988–2011. We employed weighted Cox models to test and adjust for these two selection biases. We also used complementary log-log models, adjusted for a normal distribution of frailty, to test for mortality selection effects; accelerated failure-time models to mitigate the mortality selection effect; and ordinary least squares regression to test for healthy participant effects. The link between class II/III obesity and mortality weakens at older ages. We did not find evidence for significant mortality selection or healthy participant effects. Also, even if the healthy participant effects were stronger among obese adults, they are not strong enough to produce a weakening association between obesity and morbidity at higher ages at the time of the survey. Therefore, neither of these selection biases explains the diminishing effect of class II/III obesity on mortality over the life course. PMID:26841215

  11. A General Framework for Considering Selection Bias in EHR-Based Studies: What Data Are Observed and Why?

    PubMed Central

    Haneuse, Sebastien; Daniels, Michael

    2016-01-01

    Electronic health records (EHR) data are increasingly seen as a resource for cost-effective comparative effectiveness research (CER). Since EHR data are collected primarily for clinical and/or billing purposes, their use for CER requires consideration of numerous methodologic challenges including the potential for confounding bias, due to a lack of randomization, and for selection bias, due to missing data. In contrast to the recent literature on confounding bias in EHR-based CER, virtually no attention has been paid to selection bias possibly due to the belief that standard methods for missing data can be readily-applied. Such methods, however, hinge on an overly simplistic view of the available/missing EHR data, so that their application in the EHR setting will often fail to completely control selection bias. Motivated by challenges we face in an on-going EHR-based comparative effectiveness study of choice of antidepressant treatment and long-term weight change, we propose a new general framework for selection bias in EHR-based CER. Crucially, the framework provides structure within which researchers can consider the complex interplay between numerous decisions, made by patients and health care providers, which give rise to health-related information being recorded in the EHR system, as well as the wide variability across EHR systems themselves. This, in turn, provides structure within which: (i) the transparency of assumptions regarding missing data can be enhanced, (ii) factors relevant to each decision can be elicited, and (iii) statistical methods can be better aligned with the complexity of the data. PMID:27668265

  12. A General Framework for Considering Selection Bias in EHR-Based Studies: What Data Are Observed and Why?

    PubMed Central

    Haneuse, Sebastien; Daniels, Michael

    2016-01-01

    Electronic health records (EHR) data are increasingly seen as a resource for cost-effective comparative effectiveness research (CER). Since EHR data are collected primarily for clinical and/or billing purposes, their use for CER requires consideration of numerous methodologic challenges including the potential for confounding bias, due to a lack of randomization, and for selection bias, due to missing data. In contrast to the recent literature on confounding bias in EHR-based CER, virtually no attention has been paid to selection bias possibly due to the belief that standard methods for missing data can be readily-applied. Such methods, however, hinge on an overly simplistic view of the available/missing EHR data, so that their application in the EHR setting will often fail to completely control selection bias. Motivated by challenges we face in an on-going EHR-based comparative effectiveness study of choice of antidepressant treatment and long-term weight change, we propose a new general framework for selection bias in EHR-based CER. Crucially, the framework provides structure within which researchers can consider the complex interplay between numerous decisions, made by patients and health care providers, which give rise to health-related information being recorded in the EHR system, as well as the wide variability across EHR systems themselves. This, in turn, provides structure within which: (i) the transparency of assumptions regarding missing data can be enhanced, (ii) factors relevant to each decision can be elicited, and (iii) statistical methods can be better aligned with the complexity of the data.

  13. Bias Selective Operation of Sb-Based Two-Color Photodetectors

    NASA Technical Reports Server (NTRS)

    Abedin, M. N.; Refaat, Tamer F.; Bhat, Ishwara B.; Xiao, Yegao; Johnson, David G.

    2006-01-01

    Multicolor detectors have a strong potential to replace conventional single-color detectors in application dealing with the simultaneous detection of more than one wavelength. This will lead to the reduction of heavy and complex optical components now required for spectral discrimination for multi-wavelengths applications. This multicolor technology is simpler, lighter, compact and cheaper with respect to the single-color ones. In this paper, Sb-based two-color detectors fabrication and characterization are presented. The color separation is achieved by fabricating dual band pn junction on a GaSb substrate. The first band consists of an InGaAsSb pn junction for long wavelength detection, while the second band consists of a GaSb pn junction for shorter wavelength detection. Three metal contacts were deposited to access the individual junctions. Surface morphology of multi-layer thin films and also device characteristics of quasi-dual band photodetector were characterized using standard optical microscope and electro-optic techniques respectively. Dark current measurements illustrated the diode behavior of both lattice-matched detector bands. Spectral response measurements indicated either independent operation of both detectors simultaneously, or selective operation of one detector, by the polarity of the bias voltage, while serially accessing both devices.

  14. Athletic performance and birth month: is the relative age effect more than just selection bias?

    PubMed

    Sandercock, G R H; Ogunleye, A A; Parry, D A; Cohen, D D; Taylor, M J D; Voss, C

    2014-11-01

    The aim of this study was to determine if month of birth affects performance in 3 tests of physical function in children and adolescents. We measured cardiorespiratory fitness, handgrip strength and lower-body power expressed them relative to (whole year) age then compared scores between calendar year birth-months. We also expressed test performance as the likelihood of achieving criterion-referenced fitness standards. There were significant main effects of birth-month for cardiorespiratory fitness (F=4.54, p<0.001), strength (F=6.81, p<0.001) and power (F=3.67, p<0.001). Children born in November were fitter and more powerful than those born at other times, particularly the summer months (April, May and June). October-born children were stronger than those born in all months except September and November. This relationship was evident despite controlling for decimal age and despite no significant inter-month differences in anthropometric characteristics.There is a clear physical advantage for those born in the autumn and this may explain some of the bias in sports selection attributed to the relative age effect, particularly when the British school-year (September) cut-off is used.

  15. Ion current rectification inversion in conic nanopores: nonequilibrium ion transport biased by ion selectivity and spatial asymmetry.

    PubMed

    Yan, Yu; Wang, Lin; Xue, Jianming; Chang, Hsueh-Chia

    2013-01-28

    We show both theoretically and experimentally that the ion-selectivity of a conic nanopore, as defined by a normalized density of the surface charge, significantly affects ion current rectification across the pore. For weakly selective negatively charged pores, intra-pore ion transport controls the current and internal ion enrichment/depletion at positive/reverse biased voltage (current enters/leaves through the tip, respectively), which is responsible for current rectification. For strongly selective negatively charged pores under positive bias, the current can be reduced by external field focusing and concentration depletion at the tip at low ionic strengths and high voltages, respectively. These external phenomena produce a rectification inversion for highly selective pores at high (low) voltage (ionic strength). With an asymptotic analysis of the intra-pore and external ion transport, we derive simple scaling laws to quantitatively capture empirical and numerical data for ion current rectification and rectification inversion of conic nanopores.

  16. OBJECTS IN KEPLER'S MIRROR MAY BE LARGER THAN THEY APPEAR: BIAS AND SELECTION EFFECTS IN TRANSITING PLANET SURVEYS

    SciTech Connect

    Gaidos, Eric; Mann, Andrew W.

    2013-01-01

    Statistical analyses of large surveys for transiting planets such as the Kepler mission must account for systematic errors and biases. Transit detection depends not only on the planet's radius and orbital period, but also on host star properties. Thus, a sample of stars with transiting planets may not accurately represent the target population. Moreover, targets are selected using criteria such as a limiting apparent magnitude. These selection effects, combined with uncertainties in stellar radius, lead to biases in the properties of transiting planets and their host stars. We quantify possible biases in the Kepler survey. First, Eddington bias produced by a steep planet radius distribution and uncertainties in stellar radius results in a 15%-20% overestimate of planet occurrence. Second, the magnitude limit of the Kepler target catalog induces Malmquist bias toward large, more luminous stars and underestimation of the radii of about one-third of candidate planets, especially those larger than Neptune. Third, because metal-poor stars are smaller, stars with detected planets will be very slightly (<0.02 dex) more metal-poor than the target average. Fourth, uncertainties in stellar radii produce correlated errors in planet radius and stellar irradiation. A previous finding, that highly irradiated giants are more likely to have 'inflated' radii, remains significant, even accounting for this effect. In contrast, transit depth is negatively correlated with stellar metallicity even in the absence of any intrinsic correlation, and a previous claim of a negative correlation between giant planet transit depth and stellar metallicity is probably an artifact.

  17. Objects in Kepler's Mirror May be Larger Than They Appear: Bias and Selection Effects in Transiting Planet Surveys

    NASA Astrophysics Data System (ADS)

    Gaidos, Eric; Mann, Andrew W.

    2013-01-01

    Statistical analyses of large surveys for transiting planets such as the Kepler mission must account for systematic errors and biases. Transit detection depends not only on the planet's radius and orbital period, but also on host star properties. Thus, a sample of stars with transiting planets may not accurately represent the target population. Moreover, targets are selected using criteria such as a limiting apparent magnitude. These selection effects, combined with uncertainties in stellar radius, lead to biases in the properties of transiting planets and their host stars. We quantify possible biases in the Kepler survey. First, Eddington bias produced by a steep planet radius distribution and uncertainties in stellar radius results in a 15%-20% overestimate of planet occurrence. Second, the magnitude limit of the Kepler target catalog induces Malmquist bias toward large, more luminous stars and underestimation of the radii of about one-third of candidate planets, especially those larger than Neptune. Third, because metal-poor stars are smaller, stars with detected planets will be very slightly (<0.02 dex) more metal-poor than the target average. Fourth, uncertainties in stellar radii produce correlated errors in planet radius and stellar irradiation. A previous finding, that highly irradiated giants are more likely to have "inflated" radii, remains significant, even accounting for this effect. In contrast, transit depth is negatively correlated with stellar metallicity even in the absence of any intrinsic correlation, and a previous claim of a negative correlation between giant planet transit depth and stellar metallicity is probably an artifact.

  18. Pangenome Evidence for Higher Codon Usage Bias and Stronger Translational Selection in Core Genes of Escherichia coli.

    PubMed

    Sun, Shixiang; Xiao, Jingfa; Zhang, Huiyong; Zhang, Zhang

    2016-01-01

    Codon usage bias, as a combined interplay from mutation and selection, has been intensively studied in Escherichia coli. However, codon usage analysis in an E. coli pangenome remains unexplored and the relative importance of mutation and selection acting on core genes and strain-specific genes is unknown. Here we perform comprehensive codon usage analyses based on a collection of multiple complete genome sequences of E. coli. Our results show that core genes that are present in all strains have higher codon usage bias than strain-specific genes that are unique to single strains. We further explore the forces in influencing codon usage and investigate the difference of the major force between core and strain-specific genes. Our results demonstrate that although mutation may exert genome-wide influences on codon usage acting similarly in different gene sets, selection dominates as an important force to shape biased codon usage as genes are present in an increased number of strains. Together, our results provide important insights for better understanding genome plasticity and complexity as well as evolutionary mechanisms behind codon usage bias. PMID:27536275

  19. Pangenome Evidence for Higher Codon Usage Bias and Stronger Translational Selection in Core Genes of Escherichia coli

    PubMed Central

    Sun, Shixiang; Xiao, Jingfa; Zhang, Huiyong; Zhang, Zhang

    2016-01-01

    Codon usage bias, as a combined interplay from mutation and selection, has been intensively studied in Escherichia coli. However, codon usage analysis in an E. coli pangenome remains unexplored and the relative importance of mutation and selection acting on core genes and strain-specific genes is unknown. Here we perform comprehensive codon usage analyses based on a collection of multiple complete genome sequences of E. coli. Our results show that core genes that are present in all strains have higher codon usage bias than strain-specific genes that are unique to single strains. We further explore the forces in influencing codon usage and investigate the difference of the major force between core and strain-specific genes. Our results demonstrate that although mutation may exert genome-wide influences on codon usage acting similarly in different gene sets, selection dominates as an important force to shape biased codon usage as genes are present in an increased number of strains. Together, our results provide important insights for better understanding genome plasticity and complexity as well as evolutionary mechanisms behind codon usage bias. PMID:27536275

  20. Biased Exposure–Health Effect Estimates from Selection in Cohort Studies: Are Environmental Studies at Particular Risk?

    PubMed Central

    Sparrow, David; Hu, Howard; Power, Melinda C.

    2015-01-01

    Background The process of creating a cohort or cohort substudy may induce misleading exposure–health effect associations through collider stratification bias (i.e., selection bias) or bias due to conditioning on an intermediate. Studies of environmental risk factors may be at particular risk. Objectives We aimed to demonstrate how such biases of the exposure–health effect association arise and how one may mitigate them. Methods We used directed acyclic graphs and the example of bone lead and mortality (all-cause, cardiovascular, and ischemic heart disease) among 835 white men in the Normative Aging Study (NAS) to illustrate potential bias related to recruitment into the NAS and the bone lead substudy. We then applied methods (adjustment, restriction, and inverse probability of attrition weighting) to mitigate these biases in analyses using Cox proportional hazards models to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs). Results Analyses adjusted for age at bone lead measurement, smoking, and education among all men found HRs (95% CI) for the highest versus lowest tertile of patella lead of 1.34 (0.90, 2.00), 1.46 (0.86, 2.48), and 2.01 (0.86, 4.68) for all-cause, cardiovascular, and ischemic heart disease mortality, respectively. After applying methods to mitigate the biases, the HR (95% CI) among the 637 men analyzed were 1.86 (1.12, 3.09), 2.47 (1.23, 4.96), and 5.20 (1.61, 16.8), respectively. Conclusions Careful attention to the underlying structure of the observed data is critical to identifying potential biases and methods to mitigate them. Understanding factors that influence initial study participation and study loss to follow-up is critical. Recruitment of population-based samples and enrolling participants at a younger age, before the potential onset of exposure-related health effects, can help reduce these potential pitfalls. Citation Weisskopf MG, Sparrow D, Hu H, Power MC. 2015. Biased exposure–health effect estimates

  1. A selective emotional decision-making bias elicited by facial expressions.

    PubMed

    Furl, Nicholas; Gallagher, Shannon; Averbeck, Bruno B

    2012-01-01

    Emotional and social information can sway otherwise rational decisions. For example, when participants decide between two faces that are probabilistically rewarded, they make biased choices that favor smiling relative to angry faces. This bias may arise because facial expressions evoke positive and negative emotional responses, which in turn may motivate social approach and avoidance. We tested a wide range of pictures that evoke emotions or convey social information, including animals, words, foods, a variety of scenes, and faces differing in trustworthiness or attractiveness, but we found only facial expressions biased decisions. Our results extend brain imaging and pharmacological findings, which suggest that a brain mechanism supporting social interaction may be involved. Facial expressions appear to exert special influence over this social interaction mechanism, one capable of biasing otherwise rational choices. These results illustrate that only specific types of emotional experiences can best sway our choices.

  2. A selective emotional decision-making bias elicited by facial expressions.

    PubMed

    Furl, Nicholas; Gallagher, Shannon; Averbeck, Bruno B

    2012-01-01

    Emotional and social information can sway otherwise rational decisions. For example, when participants decide between two faces that are probabilistically rewarded, they make biased choices that favor smiling relative to angry faces. This bias may arise because facial expressions evoke positive and negative emotional responses, which in turn may motivate social approach and avoidance. We tested a wide range of pictures that evoke emotions or convey social information, including animals, words, foods, a variety of scenes, and faces differing in trustworthiness or attractiveness, but we found only facial expressions biased decisions. Our results extend brain imaging and pharmacological findings, which suggest that a brain mechanism supporting social interaction may be involved. Facial expressions appear to exert special influence over this social interaction mechanism, one capable of biasing otherwise rational choices. These results illustrate that only specific types of emotional experiences can best sway our choices. PMID:22438936

  3. Determinants of hospital tax-exempt debt yields: corrections for selection and simultaneous equation bias.

    PubMed Central

    Carpenter, C E

    1992-01-01

    The cost of capital for hospitals is a topic of continuing interest as Medicare's new capital payment policy is implemented. This study examines the determinants of tax-exempt revenue bond yields, the primary source of long-term capital for hospitals. Two important methodological issues are addressed. A probit analysis estimates the probability that a hospital or system will be observed in the tax-exempt market. A selection-corrected two-stage least squares analysis allows for the simultaneous determination of bond yield and bond size. The study is based on a sample of hospitals that issued tax-exempt revenue bonds in 1982-1984, the years immediately surrounding implementation of Medicare's new payment system based on diagnosis-related groups, and an equal number of hospitals not in the market during the study period. Results suggest that hospital systems and hospitals with high occupancy rates are most likely to enter the tax-exempt revenue bond market. The yield equation suggests that hospital-specific variables may not be good predictors of the cost of capital once estimates are corrected for selection. PMID:1464540

  4. Selection bias, vote counting, and money-priming effects: A comment on Rohrer, Pashler, and Harris (2015) and Vohs (2015).

    PubMed

    Vadillo, Miguel A; Hardwicke, Tom E; Shanks, David R

    2016-05-01

    When a series of studies fails to replicate a well-documented effect, researchers might be tempted to use a "vote counting" approach to decide whether the effect is reliable-that is, simply comparing the number of successful and unsuccessful replications. Vohs's (2015) response to the absence of money priming effects reported by Rohrer, Pashler, and Harris (2015) provides an example of this approach. Unfortunately, vote counting is a poor strategy to assess the reliability of psychological findings because it neglects the impact of selection bias and questionable research practices. In the present comment, we show that a range of meta-analytic tools indicate irregularities in the money priming literature discussed by Rohrer et al. and Vohs, which all point to the conclusion that these effects are distorted by selection bias, reporting biases, or p-hacking. This could help to explain why money-priming effects have proven unreliable in a number of direct replication attempts in which biases have been minimized through preregistration or transparent reporting. Our major conclusion is that the simple proportion of significant findings is a poor guide to the reliability of research and that preregistered replications are an essential means to assess the reliability of money-priming effects. PMID:27077759

  5. Selection Bias, Vote Counting, and Money-Priming Effects: A Comment on Rohrer, Pashler, and Harris (2015) and Vohs (2015)

    PubMed Central

    2016-01-01

    When a series of studies fails to replicate a well-documented effect, researchers might be tempted to use a “vote counting” approach to decide whether the effect is reliable—that is, simply comparing the number of successful and unsuccessful replications. Vohs’s (2015) response to the absence of money priming effects reported by Rohrer, Pashler, and Harris (2015) provides an example of this approach. Unfortunately, vote counting is a poor strategy to assess the reliability of psychological findings because it neglects the impact of selection bias and questionable research practices. In the present comment, we show that a range of meta-analytic tools indicate irregularities in the money priming literature discussed by Rohrer et al. and Vohs, which all point to the conclusion that these effects are distorted by selection bias, reporting biases, or p-hacking. This could help to explain why money-priming effects have proven unreliable in a number of direct replication attempts in which biases have been minimized through preregistration or transparent reporting. Our major conclusion is that the simple proportion of significant findings is a poor guide to the reliability of research and that preregistered replications are an essential means to assess the reliability of money-priming effects. PMID:27077759

  6. Selection bias, vote counting, and money-priming effects: A comment on Rohrer, Pashler, and Harris (2015) and Vohs (2015).

    PubMed

    Vadillo, Miguel A; Hardwicke, Tom E; Shanks, David R

    2016-05-01

    When a series of studies fails to replicate a well-documented effect, researchers might be tempted to use a "vote counting" approach to decide whether the effect is reliable-that is, simply comparing the number of successful and unsuccessful replications. Vohs's (2015) response to the absence of money priming effects reported by Rohrer, Pashler, and Harris (2015) provides an example of this approach. Unfortunately, vote counting is a poor strategy to assess the reliability of psychological findings because it neglects the impact of selection bias and questionable research practices. In the present comment, we show that a range of meta-analytic tools indicate irregularities in the money priming literature discussed by Rohrer et al. and Vohs, which all point to the conclusion that these effects are distorted by selection bias, reporting biases, or p-hacking. This could help to explain why money-priming effects have proven unreliable in a number of direct replication attempts in which biases have been minimized through preregistration or transparent reporting. Our major conclusion is that the simple proportion of significant findings is a poor guide to the reliability of research and that preregistered replications are an essential means to assess the reliability of money-priming effects.

  7. Optogenetic stimulation in a computational model of the basal ganglia biases action selection and reward prediction error.

    PubMed

    Berthet, Pierre; Lansner, Anders

    2014-01-01

    Optogenetic stimulation of specific types of medium spiny neurons (MSNs) in the striatum has been shown to bias the selection of mice in a two choices task. This shift is dependent on the localisation and on the intensity of the stimulation but also on the recent reward history. We have implemented a way to simulate this increased activity produced by the optical flash in our computational model of the basal ganglia (BG). This abstract model features the direct and indirect pathways commonly described in biology, and a reward prediction pathway (RP). The framework is similar to Actor-Critic methods and to the ventral/dorsal distinction in the striatum. We thus investigated the impact on the selection caused by an added stimulation in each of the three pathways. We were able to reproduce in our model the bias in action selection observed in mice. Our results also showed that biasing the reward prediction is sufficient to create a modification in the action selection. However, we had to increase the percentage of trials with stimulation relative to that in experiments in order to impact the selection. We found that increasing only the reward prediction had a different effect if the stimulation in RP was action dependent (only for a specific action) or not. We further looked at the evolution of the change in the weights depending on the stage of learning within a block. A bias in RP impacts the plasticity differently depending on that stage but also on the outcome. It remains to experimentally test how the dopaminergic neurons are affected by specific stimulations of neurons in the striatum and to relate data to predictions of our model. PMID:24614169

  8. Optogenetic Stimulation in a Computational Model of the Basal Ganglia Biases Action Selection and Reward Prediction Error

    PubMed Central

    Berthet, Pierre; Lansner, Anders

    2014-01-01

    Optogenetic stimulation of specific types of medium spiny neurons (MSNs) in the striatum has been shown to bias the selection of mice in a two choices task. This shift is dependent on the localisation and on the intensity of the stimulation but also on the recent reward history. We have implemented a way to simulate this increased activity produced by the optical flash in our computational model of the basal ganglia (BG). This abstract model features the direct and indirect pathways commonly described in biology, and a reward prediction pathway (RP). The framework is similar to Actor-Critic methods and to the ventral/dorsal distinction in the striatum. We thus investigated the impact on the selection caused by an added stimulation in each of the three pathways. We were able to reproduce in our model the bias in action selection observed in mice. Our results also showed that biasing the reward prediction is sufficient to create a modification in the action selection. However, we had to increase the percentage of trials with stimulation relative to that in experiments in order to impact the selection. We found that increasing only the reward prediction had a different effect if the stimulation in RP was action dependent (only for a specific action) or not. We further looked at the evolution of the change in the weights depending on the stage of learning within a block. A bias in RP impacts the plasticity differently depending on that stage but also on the outcome. It remains to experimentally test how the dopaminergic neurons are affected by specific stimulations of neurons in the striatum and to relate data to predictions of our model. PMID:24614169

  9. Estimating Gene Expression and Codon-Specific Translational Efficiencies, Mutation Biases, and Selection Coefficients from Genomic Data Alone.

    PubMed

    Gilchrist, Michael A; Chen, Wei-Chen; Shah, Premal; Landerer, Cedric L; Zaretzki, Russell

    2015-05-14

    Extracting biologically meaningful information from the continuing flood of genomic data is a major challenge in the life sciences. Codon usage bias (CUB) is a general feature of most genomes and is thought to reflect the effects of both natural selection for efficient translation and mutation bias. Here we present a mechanistically interpretable, Bayesian model (ribosome overhead costs Stochastic Evolutionary Model of Protein Production Rate [ROC SEMPPR]) to extract meaningful information from patterns of CUB within a genome. ROC SEMPPR is grounded in population genetics and allows us to separate the contributions of mutational biases and natural selection against translational inefficiency on a gene-by-gene and codon-by-codon basis. Until now, the primary disadvantage of similar approaches was the need for genome scale measurements of gene expression. Here, we demonstrate that it is possible to both extract accurate estimates of codon-specific mutation biases and translational efficiencies while simultaneously generating accurate estimates of gene expression, rather than requiring such information. We demonstrate the utility of ROC SEMPPR using the Saccharomyces cerevisiae S288c genome. When we compare our model fits with previous approaches we observe an exceptionally high agreement between estimates of both codon-specific parameters and gene expression levels ([Formula: see text] in all cases). We also observe strong agreement between our parameter estimates and those derived from alternative data sets. For example, our estimates of mutation bias and those from mutational accumulation experiments are highly correlated ([Formula: see text]). Our estimates of codon-specific translational inefficiencies and tRNA copy number-based estimates of ribosome pausing time ([Formula: see text]), and mRNA and ribosome profiling footprint-based estimates of gene expression ([Formula: see text]) are also highly correlated, thus supporting the hypothesis that selection against

  10. Neurons in the Nucleus Accumbens Promote Selection Bias for Nearer Objects

    PubMed Central

    Morrison, Sara E.

    2014-01-01

    Both animals and humans often prefer rewarding options that are nearby over those that are distant, but the neural mechanisms underlying this bias are unclear. Here we present evidence that a proximity signal encoded by neurons in the nucleus accumbens drives proximate reward bias by promoting impulsive approach to nearby reward-associated objects. On a novel decision-making task, rats chose the nearer option even when it resulted in greater effort expenditure and delay to reward; therefore, proximate reward bias was unlikely to be caused by effort or delay discounting. The activity of individual neurons in the nucleus accumbens did not consistently encode the reward or effort associated with specific alternatives, suggesting that it does not participate in weighing the values of options. In contrast, proximity encoding was consistent and did not depend on the subsequent choice, implying that accumbens activity drives approach to the nearest rewarding option regardless of its specific associated reward size or effort level. PMID:25319709

  11. Recruitment and Selection Strategies in Optometric Education towards Addressing Human Resource Disparities in Sub-Saharan Africa

    ERIC Educational Resources Information Center

    Moodley, V. R.; Loughman, James; Naidoo, K. S.

    2015-01-01

    The dire need for eye care services and a dearth of human resources (HR) in sub-Saharan Africa motivated the setting up of new optometry programmes. However, to make a meaningful impact, geographical, gender, economic and educational disparities must additionally be addressed. A qualitative study utilizing purposive sampling to select academic…

  12. Picture Novelty Influences Response Selection and Inhibition: The Role of the In-Group Bias and Task-Difficulty

    PubMed Central

    Zinchenko, Artyom; Mahmud, Waich; Alam, Musrura Mefta; Kabir, Nadia; Al-Amin, Md. Mamun

    2016-01-01

    The human visual system prioritizes processing of novel information, leading to faster detection of novel stimuli. Novelty facilitates conflict resolution through the enhanced early perceptual processing. However, the role of novel information processing during the conflict-related response selection and inhibition remains unclear. Here, we used a face-gender classification version of the Simon task and manipulated task-difficulty and novelty of task-relevant information. The novel quality of stimuli was made task-irrelevant, and an in-group bias was tightly controlled by manipulation of a gender of picture stimuli. We found that the in-group bias modulated the role of novelty in executive control. Novel opposite-sex stimuli facilitated response inhibition only when the task was not demanding. By contrast, novelty enhanced response selection irrespective of the in-group factor when task-difficulty was increased. These findings support the in-group bias mechanism of visual processing, in cases when attentional resources are not limited by a demanding task. The results are further discussed along the lines of the attentional load theory and neural mechanisms of response-inhibition and locomotor activity. In conclusion, our data showed that processing of novel information may enhance executive control through facilitated response selection and inhibition. PMID:27788213

  13. Selection Bias When Using Instrumental Variable Methods to Compare Two Treatments But More Than Two Treatments Are Available.

    PubMed

    Ertefaie, Ashkan; Small, Dylan; Flory, James; Hennessy, Sean

    2016-05-01

    Instrumental variable (IV) methods are widely used to adjust for the bias in estimating treatment effects caused by unmeasured confounders in observational studies. It is common that a comparison between two treatments is focused on and that only subjects receiving one of these two treatments are considered in the analysis even though more than two treatments are available. In this paper, we provide empirical and theoretical evidence that the IV methods may result in biased treatment effects if applied on a data set in which subjects are preselected based on their received treatments. We frame this as a selection bias problem and propose a procedure that identifies the treatment effect of interest as a function of a vector of sensitivity parameters. We also list assumptions under which analyzing the preselected data does not lead to a biased treatment effect estimate. The performance of the proposed method is examined using simulation studies. We applied our method on The Health Improvement Network (THIN) database to estimate the comparative effect of metformin and sulfonylureas on weight gain among diabetic patients. PMID:27227722

  14. Estimates of External Validity Bias When Impact Evaluations Select Sites Purposively

    ERIC Educational Resources Information Center

    Stuart, Elizabeth A.; Olsen, Robert B.; Bell, Stephen H.; Orr, Larry L.

    2012-01-01

    While there has been some increasing interest in external validity, most work to this point has been in assessing the similarity of a randomized trial sample and a population of interest (e.g., Stuart et al., 2010; Tipton, 2011). The goal of this research is to calculate empirical estimates of the external validity bias in educational intervention…

  15. The effects of recall errors and of selection bias in epidemiologic studies of mobile phone use and cancer risk.

    PubMed

    Vrijheid, Martine; Deltour, Isabelle; Krewski, Daniel; Sanchez, Marie; Cardis, Elisabeth

    2006-07-01

    This paper examines the effects of systematic and random errors in recall and of selection bias in case-control studies of mobile phone use and cancer. These sensitivity analyses are based on Monte-Carlo computer simulations and were carried out within the INTERPHONE Study, an international collaborative case-control study in 13 countries. Recall error scenarios simulated plausible values of random and systematic, non-differential and differential recall errors in amount of mobile phone use reported by study subjects. Plausible values for the recall error were obtained from validation studies. Selection bias scenarios assumed varying selection probabilities for cases and controls, mobile phone users, and non-users. Where possible these selection probabilities were based on existing information from non-respondents in INTERPHONE. Simulations used exposure distributions based on existing INTERPHONE data and assumed varying levels of the true risk of brain cancer related to mobile phone use. Results suggest that random recall errors of plausible levels can lead to a large underestimation in the risk of brain cancer associated with mobile phone use. Random errors were found to have larger impact than plausible systematic errors. Differential errors in recall had very little additional impact in the presence of large random errors. Selection bias resulting from underselection of unexposed controls led to J-shaped exposure-response patterns, with risk apparently decreasing at low to moderate exposure levels. The present results, in conjunction with those of the validation studies conducted within the INTERPHONE study, will play an important role in the interpretation of existing and future case-control studies of mobile phone use and cancer risk, including the INTERPHONE study.

  16. Selection bias in the link between child wantedness and child survival: theory and data from Matlab, Bangladesh.

    PubMed

    Bishai, David; Razzaque, Abdur; Christiansen, Susan; Mustafa, A H M Golam; Hindin, Michelle

    2015-02-01

    We examine the potential effects of selection bias on the association between unwanted births and child mortality from 7,942 women from Matlab, Bangladesh who declared birth intentions in 1990 prior to conceiving pregnancies. We explore and test two opposing reasons for bias in the distribution of observed births. First, some women who report not wanting more children could face starvation or frailty; and if these women are infecund, the remaining unwanted births would appear more healthy. Second, some women who report not wanting more children could have social privileges in acquiring medical services, abortion, and contraceptives; and if these women avoid births, the remaining unwanted births would appear less healthy. We find (1) no overall effect of unwantedness on child survival in rural Bangladesh in the 1990s, (2) no evidence that biological processes are spuriously making the birth cohort look more healthy, and (3) some evidence that higher schooling for women who avoid unwanted births is biasing the observed sample to make unwanted births look less healthy. Efforts to understand the effect of unwantedness in data sets that do not control for complex patterns of selective birth may be misleading and require more cautious interpretation.

  17. Selection bias in the link between in child wantedness and child survival: Theory and data from Matlab, Bangladesh

    PubMed Central

    Bishai, David; Razzaque, Abdur; Christiansen, Susan; Golam Mustafa, A.H. M.; Hindin, Michelle

    2014-01-01

    We examine the potential effects of selection bias on the association between unwanted births and child mortality from 7942 women from Matlab, Bangladesh who declared birth intentions in 1990 prior to conceiving pregnancies. We explore and test two opposing reasons for bias in the distribution of observed births: 1) Some women who report not wanting more children could face starvation or frailty and if these women are sub-fecund, the remaining unwanted births would appear more healthy; 2) Some women who report not wanting more children could have social privileges in acquiring medical services, abortion, and contraception and if these women avoid births the remaining unwanted births would appear less healthy. We find: A)No overall effect of unwantedness on child survival in rural Bangladesh in the 1990s; B)No evidence that biological processes are spuriously making the birth cohort look more healthy; and C)Some evidence that higher schooling in women who avoid unwanted births is biasing the observed sample to make unwanted births look less healthy. Efforts to understand the effect of unwantedness in datasets that do not control for complex patterns of selective birth may be misleading and require more cautious interpretation. PMID:25585643

  18. Discovery of Potent and Selective Agonists of δ Opioid Receptor by Revisiting the "Message-Address" Concept.

    PubMed

    Shen, Qing; Qian, Yuanyuan; Huang, Xiaoqin; Xu, Xuejun; Li, Wei; Liu, Jinggen; Fu, Wei

    2016-04-14

    The classic "message-address" concept was proposed to address the binding of endogenous peptides to the opioid receptors and was later successfully applied in the discovery of the first nonpeptide δ opioid receptor (DOR) antagonist naltrindole. By revisiting this concept, and based on the structure of tramadol, we designed a series of novel compounds that act as highly potent and selective agonists of DOR among which (-)-6j showed the highest affinity (K i = 2.7 nM), best agonistic activity (EC50 = 2.6 nM), and DOR selectivity (more than 1000-fold over the other two subtype opioid receptors). Molecular docking studies suggest that the "message" part of (-)-6j interacts with residue Asp128(3.32) and a neighboring water molecule, and the "address" part of (-)-6j packs with hydrophobic residues Leu300(7.35), Val281(6.55), and Trp284(6.58), rendering DOR selectivity. The discovery of novel compound (-)-6j, and the obtained insights into DOR-agonist binding will help us design more potent and selective DOR agonists.

  19. Addressing Bias in Small RNA Library Preparation for Sequencing: A New Protocol Recovers MicroRNAs that Evade Capture by Current Methods.

    PubMed

    Baran-Gale, Jeanette; Kurtz, C Lisa; Erdos, Michael R; Sison, Christina; Young, Alice; Fannin, Emily E; Chines, Peter S; Sethupathy, Praveen

    2015-01-01

    Recent advances in sequencing technology have helped unveil the unexpected complexity and diversity of small RNAs. A critical step in small RNA library preparation for sequencing is the ligation of adapter sequences to both the 5' and 3' ends of small RNAs. Studies have shown that adapter ligation introduces a significant but widely unappreciated bias in the results of high-throughput small RNA sequencing. We show that due to this bias the two widely used Illumina library preparation protocols produce strikingly different microRNA (miRNA) expression profiles in the same batch of cells. There are 102 highly expressed miRNAs that are >5-fold differentially detected and some miRNAs, such as miR-24-3p, are over 30-fold differentially detected. While some level of bias in library preparation is not surprising, the apparent massive differential bias between these two widely used adapter sets is not well appreciated. In an attempt to mitigate this bias, the new Bioo Scientific NEXTflex V2 protocol utilizes a pool of adapters with random nucleotides at the ligation boundary. We show that this protocol is able to detect robustly several miRNAs that evade capture by the Illumina-based methods. While these analyses do not indicate a definitive gold standard for small RNA library preparation, the results of the NEXTflex protocol do correlate best with RT-qPCR. As increasingly more laboratories seek to study small RNAs, researchers should be aware of the extent to which the results may differ with different protocols, and should make an informed decision about the protocol that best fits their study.

  20. Addressing Bias in Small RNA Library Preparation for Sequencing: A New Protocol Recovers MicroRNAs that Evade Capture by Current Methods

    PubMed Central

    Baran-Gale, Jeanette; Kurtz, C. Lisa; Erdos, Michael R.; Sison, Christina; Young, Alice; Fannin, Emily E.; Chines, Peter S.; Sethupathy, Praveen

    2015-01-01

    Recent advances in sequencing technology have helped unveil the unexpected complexity and diversity of small RNAs. A critical step in small RNA library preparation for sequencing is the ligation of adapter sequences to both the 5′ and 3′ ends of small RNAs. Studies have shown that adapter ligation introduces a significant but widely unappreciated bias in the results of high-throughput small RNA sequencing. We show that due to this bias the two widely used Illumina library preparation protocols produce strikingly different microRNA (miRNA) expression profiles in the same batch of cells. There are 102 highly expressed miRNAs that are >5-fold differentially detected and some miRNAs, such as miR-24-3p, are over 30-fold differentially detected. While some level of bias in library preparation is not surprising, the apparent massive differential bias between these two widely used adapter sets is not well appreciated. In an attempt to mitigate this bias, the new Bioo Scientific NEXTflex V2 protocol utilizes a pool of adapters with random nucleotides at the ligation boundary. We show that this protocol is able to detect robustly several miRNAs that evade capture by the Illumina-based methods. While these analyses do not indicate a definitive gold standard for small RNA library preparation, the results of the NEXTflex protocol do correlate best with RT-qPCR. As increasingly more laboratories seek to study small RNAs, researchers should be aware of the extent to which the results may differ with different protocols, and should make an informed decision about the protocol that best fits their study. PMID:26734062

  1. Meeting Educators Where They Are: Professional Development to Address Selective Mutism

    ERIC Educational Resources Information Center

    Harwood, Debra; Bork, Po-Ling

    2011-01-01

    Children with selective mutism (SM) present unique challenges for teachers. Typically, children with SM have such an immense anxiety associated with being seen or heard speaking they fail to speak inside the classroom and particularly with teachers. This article reports on the effectiveness of a small-scale exploratory study involving 22…

  2. The Swift gamma-ray burst redshift distribution: selection biases and optical brightness evolution at high z?

    NASA Astrophysics Data System (ADS)

    Coward, D. M.; Howell, E. J.; Branchesi, M.; Stratta, G.; Guetta, D.; Gendre, B.; Macpherson, D.

    2013-07-01

    We employ realistic constraints on astrophysical and instrumental selection effects to model the gamma-ray burst (GRB) redshift distribution using Swift triggered redshift samples acquired from optical afterglows and The Optically Unbiased GRB Host survey. Models for the Malmquist bias, redshift desert, and the fraction of afterglows missing because of host galaxy dust extinction are used to show how the `true' GRB redshift distribution is distorted to its presently observed biased distribution. We also investigate another selection effect arising from a correlation between Eiso and Lopt. The analysis, which accounts for the missing fraction of redshifts in the two data subsets, shows that a combination of selection effects (both instrumental and astrophysical) can describe the observed GRB redshift distribution. Furthermore, the observed distribution is compatible with a GRB rate evolution that tracks the global star formation rate, although the rate at high z cannot be constrained with confidence. Taking optical selection effects into account, it may not be necessary to invoke high-energy GRB luminosity evolution with redshift to explain the observed GRB rate at high z.

  3. Optical Addressing Electronic Tongue Based on Low Selective Photovoltaic Transducer with Nanoporous Silicon Layer.

    PubMed

    Litvinenko, S V; Bielobrov, D O; Lysenko, V; Skryshevsky, V A

    2016-12-01

    The electronic tongue based on the array of low selective photovoltaic (PV) sensors and principal component analysis is proposed for detection of various alcohol solutions. A sensor array is created at the forming of p-n junction on silicon wafer with porous silicon layer on the opposite side. A dynamical set of sensors is formed due to the inhomogeneous distribution of the surface recombination rate at this porous silicon side. The sensitive to molecular adsorption photocurrent is induced at the scanning of this side by laser beam. Water, ethanol, iso-propanol, and their mixtures were selected for testing. It is shown that the use of the random dispersion of surface recombination rates on different spots of the rear side of p-n junction and principal component analysis of PV signals allows identifying mentioned liquid substances and their mixtures. PMID:27553383

  4. Optical Addressing Electronic Tongue Based on Low Selective Photovoltaic Transducer with Nanoporous Silicon Layer

    NASA Astrophysics Data System (ADS)

    Litvinenko, S. V.; Bielobrov, D. O.; Lysenko, V.; Skryshevsky, V. A.

    2016-08-01

    The electronic tongue based on the array of low selective photovoltaic (PV) sensors and principal component analysis is proposed for detection of various alcohol solutions. A sensor array is created at the forming of p-n junction on silicon wafer with porous silicon layer on the opposite side. A dynamical set of sensors is formed due to the inhomogeneous distribution of the surface recombination rate at this porous silicon side. The sensitive to molecular adsorption photocurrent is induced at the scanning of this side by laser beam. Water, ethanol, iso-propanol, and their mixtures were selected for testing. It is shown that the use of the random dispersion of surface recombination rates on different spots of the rear side of p-n junction and principal component analysis of PV signals allows identifying mentioned liquid substances and their mixtures.

  5. Optical Addressing Electronic Tongue Based on Low Selective Photovoltaic Transducer with Nanoporous Silicon Layer.

    PubMed

    Litvinenko, S V; Bielobrov, D O; Lysenko, V; Skryshevsky, V A

    2016-12-01

    The electronic tongue based on the array of low selective photovoltaic (PV) sensors and principal component analysis is proposed for detection of various alcohol solutions. A sensor array is created at the forming of p-n junction on silicon wafer with porous silicon layer on the opposite side. A dynamical set of sensors is formed due to the inhomogeneous distribution of the surface recombination rate at this porous silicon side. The sensitive to molecular adsorption photocurrent is induced at the scanning of this side by laser beam. Water, ethanol, iso-propanol, and their mixtures were selected for testing. It is shown that the use of the random dispersion of surface recombination rates on different spots of the rear side of p-n junction and principal component analysis of PV signals allows identifying mentioned liquid substances and their mixtures.

  6. The use of automatic wire coding to evaluate control selection bias in the Savitz et al. study. Final report

    SciTech Connect

    Pearson, R.L.; Wachtel, H.; Ebi, K.L.

    1998-08-01

    In the Savitz et al. case-control study performed in Denver in the mid-1980s, wire codes were found to be associated with childhood cancer, but magnetic field measurements taken at the same time were not. One explanation is that using select random digit dialing to select controls may have resulted in a deficit in controls living in VHCC homes. To evaluate this possibility, the authors wire coded several hundred thousand homes across the Denver area and then determined which homes housed ``potentially eligible`` children who Savitz could have selected as controls. Automated wire coding was done using computerized data sets of power line wiring and tax assessor records. ``Potentially eligible`` controls were identified using 1980 census data. Because the authors did not know precisely which children lived in which homes across Denver in 1985, they used two assignment processes to determine the wire code distributions of the ``potentially eligible`` controls. First census block data were used to weight the number of homes in each wire code category by the fraction of homes occupied by potentially eligible children, or by the number of children per block. Second, a Monte Carlo assignment process was used to assign children to homes within each block. The authors observed limited evidence of control selection bias especially for VHCC and Buried wire code when they compared the distributions of various versions of these inputed controls to the wire code distribution of the Savitz controls. These results were partially supported when the authors selected 100 sets of controls from each of the Monte Carlo populations to determine if the apparent disagreement of Savitz` controls with the inputed population controls could be due to chance. Given the fundamental limitation of not knowing which homes in 1985 had ``potentially eligible`` children, suggestions of control selection bias must be considered tentative and suggestive only.

  7. Measuring the impact of health insurance with a correction for selection bias--a case study of Ecuador.

    PubMed

    Waters, H R

    1999-08-01

    This article develops and uses methodologies to evaluate the impact of publicly-financed health insurance programmes on the use of health care. Using univariate and bivariate probit estimation techniques, the study tests and corrects for endogeneity resulting from selection bias. Potential endogeneity arises from the choice to be insured, eligibility for insurance, and differences in individuals' health status. The setting for the study is the country of Ecuador. The General Health Insurance (GHI) programme, which primarily covers workers in the formal sector of the economy, is found to have a strong positive association with the use of curative health care after correcting for selection bias, but no significant effect on the use of preventive care. Individuals with severe illnesses who are eligible for GHI have a preference for private health care, and self-select out of the GHI programme. The Seguro Campesino Social (SSC) programme, directed at farming populations, has positive but insignificant associations with both curative and preventive care. PMID:10470552

  8. Selective serotonin 5-HT1A receptor biased agonists elicitdistinct brain activation patterns: a pharmacoMRI study

    PubMed Central

    Becker, G.; Bolbos, R.; Costes, N.; Redouté, J.; Newman-Tancredi, A.; Zimmer, L.

    2016-01-01

    Serotonin 1A (5-HT1A) receptors are involved in several physiological and pathological processes and constitute therefore an important therapeutic target. The recent pharmacological concept of biased agonism asserts that highly selective agonists can preferentially direct receptor signaling to specific intracellular responses, opening the possibility of drugs targeting a receptor subtype in specific brain regions. The present study brings additional support to this concept thanks to functional magnetic resonance imaging (7 Tesla-fMRI) in anaesthetized rats. Three 5-HT1A receptor agonists (8-OH-DPAT, F13714 and F15599) and one 5-HT1A receptor antagonist (MPPF) were compared in terms of influence on the brain blood oxygen level-dependent (BOLD) signal. Our study revealed for the first time contrasting BOLD signal patterns of biased agonists in comparison to a classical agonist and a silent antagonist. By providing functional information on the influence of pharmacological activation of 5-HT1A receptors in specific brain regions, this neuroimaging approach, translatable to the clinic, promises to be useful in exploring the new concept of biased agonism in neuropsychopharmacology. PMID:27211078

  9. Selection bias in dynamically measured supermassive black hole samples: its consequences and the quest for the most fundamental relation

    NASA Astrophysics Data System (ADS)

    Shankar, Francesco; Bernardi, Mariangela; Sheth, Ravi K.; Ferrarese, Laura; Graham, Alister W.; Savorgnan, Giulia; Allevato, Viola; Marconi, Alessandro; Läsker, Ronald; Lapi, Andrea

    2016-08-01

    We compare the set of local galaxies having dynamically measured black holes with a large, unbiased sample of galaxies extracted from the Sloan Digital Sky Survey. We confirm earlier work showing that the majority of black hole hosts have significantly higher velocity dispersions σ than local galaxies of similar stellar mass. We use Monte Carlo simulations to illustrate the effect on black hole scaling relations if this bias arises from the requirement that the black hole sphere of influence must be resolved to measure black hole masses with spatially resolved kinematics. We find that this selection effect artificially increases the normalization of the Mbh-σ relation by a factor of at least ˜3; the bias for the Mbh-Mstar relation is even larger. Our Monte Carlo simulations and analysis of the residuals from scaling relations both indicate that σ is more fundamental than Mstar or effective radius. In particular, the Mbh-Mstar relation is mostly a consequence of the Mbh-σ and σ-Mstar relations, and is heavily biased by up to a factor of 50 at small masses. This helps resolve the discrepancy between dynamically based black hole-galaxy scaling relations versus those of active galaxies. Our simulations also disfavour broad distributions of black hole masses at fixed σ. Correcting for this bias suggests that the calibration factor used to estimate black hole masses in active galaxies should be reduced to values of fvir ˜ 1. Black hole mass densities should also be proportionally smaller, perhaps implying significantly higher radiative efficiencies/black hole spins. Reducing black hole masses also reduces the gravitational wave signal expected from black hole mergers.

  10. Keynote address: cellular reduction of nitroimidazole drugs: potential for selective chemotherapy and diagnosis of hypoxic cells.

    PubMed

    Chapman, J D; Lee, J; Meeker, B E

    1989-04-01

    Nitroimidazole drugs were initially developed as selective radiosensitizers of hypoxic cells and, consequently, as adjuvants to improve the local control probabilities of current radiotherapies. Misonidazole (MISO), the prototype radiosensitizing drug, was found in Phase I clinical studies to cause dose-limiting neurotoxicities (mainly peripheral neuropathies). MISO was also found to be cytotoxic in the absence of radiation and to covalently bind to cellular molecules, both processes demonstrating rates much higher in hypoxic compared with oxygenated cells. It is likely that neurotoxicity, cellular cytotoxicity and adduct formation results from reactions between reduction intermediates of MISO and cellular target molecules. Spin-offs from radiosensitizer research include the synthesis and characterization of more potent hypoxic cytotoxins and the exploitation of sensitizer-adducts as probes for measuring cellular and tissue oxygen levels. Current developments in hypoxic cell cytotoxin and hypoxic cell marker research are reviewed with specific examples from studies which characterize the cellular reduction of TF-MISO, (1-(2-nitro-1-imidazolyl)-3[2,2,2-trifluoroethoxy]-2-propanol).

  11. Apparatus and method for selective area deposition of thin films on electrically biased substrates

    DOEpatents

    Zuhr, Raymond A.; Haynes, Tony E.; Golanski, Andrzej

    1994-01-01

    An ion beam deposition process for selective area deposition on a polarized substrate uses a potential applied to the substrate which allows the ionized particles to reach into selected areas for film deposition. Areas of the substrate to be left uncoated are held at a potential that repells the ionized particles.

  12. Apparatus and method for selective area deposition of thin films on electrically biased substrates

    DOEpatents

    Zuhr, R.A.; Haynes, T.E.; Golanski, A.

    1994-10-11

    An ion beam deposition process for selective area deposition on a polarized substrate uses a potential applied to the substrate which allows the ionized particles to reach into selected areas for film deposition. Areas of the substrate to be left uncoated are held at a potential that repels the ionized particles. 3 figs.

  13. Apparatus and method for selective area deposition of thin films on electrically biased substrates

    DOEpatents

    Zuhr, R.A.; Haynes, T.E.; Golanski, A.

    1999-06-08

    An ion beam deposition process for selective area deposition on a polarized substrate uses a potential applied to the substrate which allows the ionized particles to reach into selected areas for film deposition. Areas of the substrate to be left uncoated are held at a potential that repels the ionized particles. 3 figs.

  14. Apparatus and method for selective area deposition of thin films on electrically biased substrates

    DOEpatents

    Zuhr, Raymond A.; Haynes, Tony E.; Golanski, Andrzej

    1999-01-01

    An ion beam deposition process for selective area deposition on a polarized substrate uses a potential applied to the substrate which allows the ionized particles to reach into selected areas for film deposition. Areas of the substrate to be left uncoated are held at a potential that repells the ionized particles.

  15. Taking personality selection bias seriously in animal cognition research: a case study in capuchin monkeys (Sapajus apella).

    PubMed

    Morton, F Blake; Lee, Phyllis C; Buchanan-Smith, Hannah M

    2013-07-01

    In most experimental work on animal cognition, researchers attempt to control for multiple interacting variables by training subjects prior to testing, allowing subjects to participate voluntarily, and providing subjects with food rewards. However, do such methods encourage selection bias from subjects' personalities? In this study, we trained eighteen zoo-housed capuchin monkeys (Sapajus apella) for two experiments, under conditions of positive reinforcement (i.e. food rewards) and free-choice participation. Using a combination of behavioral and rater-based methods, we identified and validated five personality dimensions in these capuchins (Assertiveness, Openness, Neuroticism, Sociability, and Attentiveness). Scores on Openness were positively related to individual differences in monkey task participation, reflecting previous work showing that such individuals are often more active, curious, and willing to engage in testing. We also found a negative relationship between scores on Assertiveness and performance on tasks, which may reflect the trade-offs between speed and accuracy in these animals' decision-making. Highly Assertive individuals (the most sociable within monkey groups) may also prioritize social interactions over engaging in research. Lastly, monkeys that consistently participated and performed well on both tasks showed significantly higher Openness and lower Assertiveness compared to others, mirroring relationships found between personality, participation, and performance among all participants. Participation and performance during training was clearly biased toward individuals with particular personalities (i.e. high Openness, low Assertiveness). Results are discussed in light of the need for careful interpretation of comparative data on animal cognition and the need for researchers to take personality selection bias more seriously.

  16. Taking personality selection bias seriously in animal cognition research: a case study in capuchin monkeys (Sapajus apella).

    PubMed

    Morton, F Blake; Lee, Phyllis C; Buchanan-Smith, Hannah M

    2013-07-01

    In most experimental work on animal cognition, researchers attempt to control for multiple interacting variables by training subjects prior to testing, allowing subjects to participate voluntarily, and providing subjects with food rewards. However, do such methods encourage selection bias from subjects' personalities? In this study, we trained eighteen zoo-housed capuchin monkeys (Sapajus apella) for two experiments, under conditions of positive reinforcement (i.e. food rewards) and free-choice participation. Using a combination of behavioral and rater-based methods, we identified and validated five personality dimensions in these capuchins (Assertiveness, Openness, Neuroticism, Sociability, and Attentiveness). Scores on Openness were positively related to individual differences in monkey task participation, reflecting previous work showing that such individuals are often more active, curious, and willing to engage in testing. We also found a negative relationship between scores on Assertiveness and performance on tasks, which may reflect the trade-offs between speed and accuracy in these animals' decision-making. Highly Assertive individuals (the most sociable within monkey groups) may also prioritize social interactions over engaging in research. Lastly, monkeys that consistently participated and performed well on both tasks showed significantly higher Openness and lower Assertiveness compared to others, mirroring relationships found between personality, participation, and performance among all participants. Participation and performance during training was clearly biased toward individuals with particular personalities (i.e. high Openness, low Assertiveness). Results are discussed in light of the need for careful interpretation of comparative data on animal cognition and the need for researchers to take personality selection bias more seriously. PMID:23370784

  17. Profile of rheumatology patients willing to report adverse drug reactions: bias from selective reporting

    PubMed Central

    Protić, Dragana; Vujasinović-Stupar, Nada; Bukumirić, Zoran; Pavlov-Dolijanović, Slavica; Baltić, Snežana; Mutavdžin, Slavica; Marković-Denić, Ljiljana; Zdravković, Marija; Todorović, Zoran

    2016-01-01

    Background Adverse drug reactions (ADRs) have a significant impact on human health and health care costs. The aims of our study were to determine the profile of rheumatology patients willing to report ADRs and to identify bias in such a reporting system. Methods Semi-intensive ADRs reporting system was used in our study. Patients willing to participate (N=261) completed the questionnaire designed for the purpose of the study at the hospital admission. They were subsequently classified into two groups according to their ability to identify whether they had experienced ADRs during the previous month. Group 1 included 214 out of 261 patients who were able to identify ADRs, and group 2 consisted of 43 out of 261 patients who were not able to identify ADRs in their recent medical history. Results Group 1 patients were more significantly aware of their diagnosis than the patients from group 2. Marginal significance was found between rheumatology patients with and without neurological comorbidities regarding their awareness of ADRs. The majority of patients reported ADRs of cytotoxic drugs. The most reported ADRs were moderate gastrointestinal discomforts. Conclusion We may draw a profile of rheumatological patients willing to report ADRs: 1) The majority of them suffer from systemic inflammatory diseases and are slightly more prone to neurological comorbidities. 2) They are predominantly aware of their diagnosis but less able to identify the drugs that may cause their ADRs. 3) They tend to report mainly moderate gastrointestinal ADRs; that is, other cohorts of patients and other types of ADRs remain mainly undetected in such a reporting, which could represent a bias. Counseling and education of patients as well as developing a network for online communication might improve patients’ reporting of potential ADRs. PMID:26893547

  18. Potential selection bias in a community-based study of PSA levels in African-American men.

    PubMed

    Heeringa, S G; Alcser, K H; Doerr, K; Strawderman, M; Cooney, K; Medbery, B; Schottenfeld, D

    2001-02-01

    The first phase of the Flint Men's Health Study (FMHS) in Michigan was a community-based epidemiologic study of prostate cancer and benign prostatic hyperplasia (BPH) in African-Americans aged 40 to 79 years. An objective of the FMHS was to determine age-specified prostate specific antigen (PSA) reference ranges in a random population sample of African-American men without clinically evident prostate cancer. The FMHS study protocol included an initial in-home epidemiologic interview followed by PSA testing and a urologic examination of eligible subjects. Since the participation rate in the PSA phase of the study was under 60%, it was important to determine whether selectivity in participation biased the FMHS results for age-specific PSA distributions. Logistic regression analyses were used to investigate selectivity in the sample of subjects who participated in the PSA testing and urologic examination. Younger men, with current urologic symptoms, and with a family history of prostate cancer were more likely to participate in the PSA testing and urologic examination. Linear regression analysis indicated that greater participation by African-American men without clinically evident prostate cancer but with obstructive or irritative lower urinary tract symptoms or a family history of prostate cancer did not bias the estimated age-specific reference ranges for total PSA concentrations and free-to-total PSA ratios.

  19. Mask-less patterning of organic light emitting diodes using electrospray and selective biasing on pixel electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Sangyeob; Koo, Hyun; Cho, Sunghwan

    2015-04-01

    Wet process of soluble organic light emitting diode (OLED) materials has attracted much attention due to its potential as a large-area manufacturing process with high productivity. Electrospray (ES) deposition is one of candidates of organic thin film formation process for OLED. However, to fabricate red, green, and blue emitters for color display, a fine metal mask is required during spraying emitter materials. We demonstrate a mask-less color pixel patterning process using ES of soluble OLED materials and selective biasing on pixel electrodes and a spray nozzle. We show red and green line patterns of OLED materials. It was found that selective patterning can be allowed by coulomb repulsion between nozzle and pixel. Furthermore, we fabricated blue fluorescent OLED devices by vacuum evaporation and ES processes. The device performance of ES processed OLED showed nearly identical current-voltage characteristics and slightly lower current efficiency compared to vacuum processed OLED.

  20. Estimating the "impact" of out-of-home placement on child well-being: approaching the problem of selection bias.

    PubMed

    Berger, Lawrence M; Bruch, Sarah K; Johnson, Elizabeth I; James, Sigrid; Rubin, David

    2009-01-01

    This study used data on 2,453 children aged 4-17 from the National Survey of Child and Adolescent Well-Being and 5 analytic methods that adjust for selection factors to estimate the impact of out-of-home placement on children's cognitive skills and behavior problems. Methods included ordinary least squares (OLS) regressions and residualized change, simple change, difference-in-difference, and fixed effects models. Models were estimated using the full sample and a matched sample generated by propensity scoring. Although results from the unmatched OLS and residualized change models suggested that out-of-home placement is associated with increased child behavior problems, estimates from models that more rigorously adjust for selection bias indicated that placement has little effect on children's cognitive skills or behavior problems. PMID:19930356

  1. Sources of selection bias in evaluating social programs: An interpretation of conventional measures and evidence on the effectiveness of matching as a program evaluation method

    PubMed Central

    Heckman, James J.; Ichimura, Hidehiko; Smith, Jeffrey; Todd, Petra

    1996-01-01

    This paper decomposes the conventional measure of selection bias in observational studies into three components. The first two components are due to differences in the distributions of characteristics between participant and nonparticipant (comparison) group members: the first arises from differences in the supports, and the second from differences in densities over the region of common support. The third component arises from selection bias precisely defined. Using data from a recent social experiment, we find that the component due to selection bias, precisely defined, is smaller than the first two components. However, selection bias still represents a substantial fraction of the experimental impact estimate. The empirical performance of matching methods of program evaluation is also examined. We find that matching based on the propensity score eliminates some but not all of the measured selection bias, with the remaining bias still a substantial fraction of the estimated impact. We find that the support of the distribution of propensity scores for the comparison group is typically only a small portion of the support for the participant group. For values outside the common support, it is impossible to reliably estimate the effect of program participation using matching methods. If the impact of participation depends on the propensity score, as we find in our data, the failure of the common support condition severely limits matching compared with random assignment as an evaluation estimator. PMID:8917606

  2. Are all biases missing data problems?

    PubMed Central

    Howe, Chanelle J.; Cain, Lauren E.; Hogan, Joseph W.

    2015-01-01

    Estimating causal effects is a frequent goal of epidemiologic studies. Traditionally, there have been three established systematic threats to consistent estimation of causal effects. These three threats are bias due to confounders, selection, and measurement error. Confounding, selection, and measurement bias have typically been characterized as distinct types of biases. However, each of these biases can also be characterized as missing data problems that can be addressed with missing data solutions. Here we describe how the aforementioned systematic threats arise from missing data as well as review methods and their related assumptions for reducing each bias type. We also link the assumptions made by the reviewed methods to the missing completely at random (MCAR) and missing at random (MAR) assumptions made in the missing data framework that allow for valid inferences to be made based on the observed, incomplete data. PMID:26576336

  3. The effect of connectives on the selection of arguments: implicit consequentiality bias for the connective "but".

    PubMed

    Rigalleau, François; Guerry, Michèle; Granjon, Lionel

    2014-08-01

    Recent studies about the implicit causality of inter-personal verbs showed a symmetric implicit consequentiality bias for psychological verbs. This symmetry is less clear for action verbs because the verbs assigning the implicit cause to the object argument (e.g. "Peter protected John because he was in danger.") tend to assign the implicit consequence to the same argument (e.g. "Peter protected John so he was not hurt."). We replicated this result by comparing continuations of inter-personal events followed by a causal connective "because" or a consequence connective "so". Moreover, we found similar results when the consequence connective was replaced by a contrastive connective "but". This result was confirmed in a second experiment where we measured the time required to imagine a consistent continuation for a fragment finishing with "but s/he ...". The results were consistent with a contrastive connective introducing a denial of a consequence of the previous event. The results were consistent with a model suggesting that thematic roles and connectives can predict preferred co-reference relations. PMID:23982891

  4. The Matching Relation and Situation-Specific Bias Modulation in Professional Football Play Selection

    ERIC Educational Resources Information Center

    Stilling, Stephanie T.; Critchfield, Thomas S.

    2010-01-01

    The utility of a quantitative model depends on the extent to which its fitted parameters vary systematically with environmental events of interest. Professional football statistics were analyzed to determine whether play selection (passing versus rushing plays) could be accounted for with the generalized matching equation, and in particular…

  5. Impact of marker ascertainment bias on genomic selection accuracy and estimates of genetic diversity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genome-wide molecular markers are readily being applied to evaluate genetic diversity in germplasm collections and for making genomic selections in breeding programs. To accurately predict phenotypes and assay genetic diversity, molecular markers should assay a representative sample of the polymorp...

  6. Accounting for selection bias in species distribution models: An econometric approach on forested trees based on structural modeling

    NASA Astrophysics Data System (ADS)

    Ay, Jean-Sauveur; Guillemot, Joannès; Martin-StPaul, Nicolas K.; Doyen, Luc; Leadley, Paul

    2015-04-01

    Species distribution models (SDMs) are widely used to study and predict the outcome of global change on species. In human dominated ecosystems the presence of a given species is the result of both its ecological suitability and human footprint on nature such as land use choices. Land use choices may thus be responsible for a selection bias in the presence/absence data used in SDM calibration. We present a structural modelling approach (i.e. based on structural equation modelling) that accounts for this selection bias. The new structural species distribution model (SSDM) estimates simultaneously land use choices and species responses to bioclimatic variables. A land use equation based on an econometric model of landowner choices was joined to an equation of species response to bioclimatic variables. SSDM allows the residuals of both equations to be dependent, taking into account the possibility of shared omitted variables and measurement errors. We provide a general description of the statistical theory and a set of application on forested trees over France using databases of climate and forest inventory at different spatial resolution (from 2km to 8 km). We also compared the output of the SSDM with outputs of a classical SDM in term of bioclimatic response curves and potential distribution under current climate. According to the species and the spatial resolution of the calibration dataset, shapes of bioclimatic response curves the modelled species distribution maps differed markedly between the SSDM and classical SDMs. The magnitude and directions of these differences were dependent on the correlations between the errors from both equations and were highest for higher spatial resolutions. A first conclusion is that the use of classical SDMs can potentially lead to strong miss-estimation of the actual and future probability of presence modelled. Beyond this selection bias, the SSDM we propose represents a crucial step to account for economic constraints on tree

  7. Identifying selective visual attention biases related to fear of pain by tracking eye movements within a dot-probe paradigm.

    PubMed

    Yang, Zhou; Jackson, Todd; Gao, Xiao; Chen, Hong

    2012-08-01

    This research examined selective biases in visual attention related to fear of pain by tracking eye movements (EM) toward pain-related stimuli among the pain-fearful. EM of 21 young adults scoring high on a fear of pain measure (H-FOP) and 20 lower-scoring (L-FOP) control participants were measured during a dot-probe task that featured sensory pain-neutral, health catastrophe-neutral and neutral-neutral word pairs. Analyses indicated that the H-FOP group was more likely to direct immediate visual attention toward sensory pain and health catastrophe words than was the L-FOP group. The H-FOP group also had comparatively shorter first fixation latencies toward sensory pain and health catastrophe words. Conversely, groups did not differ on EM indices of attentional maintenance (i.e., first fixation duration, gaze duration, and average fixation duration) or reaction times to dot probes. Finally, both groups showed a cycle of disengagement followed by re-engagement toward sensory pain words relative to other word types. In sum, this research is the first to reveal biases toward pain stimuli during very early stages of visual information processing among the highly pain-fearful and highlights the utility of EM tracking as a means to evaluate visual attention as a dynamic process in the context of FOP. PMID:22717101

  8. Worry or craving? A selective review of evidence for food-related attention biases in obese individuals, eating-disorder patients, restrained eaters and healthy samples.

    PubMed

    Werthmann, Jessica; Jansen, Anita; Roefs, Anne

    2015-05-01

    Living in an 'obesogenic' environment poses a serious challenge for weight maintenance. However, many people are able to maintain a healthy weight indicating that not everybody is equally susceptible to the temptations of this food environment. The way in which someone perceives and reacts to food cues, that is, cognitive processes, could underlie differences in susceptibility. An attention bias for food could be such a cognitive factor that contributes to overeating. However, an attention bias for food has also been implicated with restrained eating and eating-disorder symptomatology. The primary aim of the present review was to determine whether an attention bias for food is specifically related to obesity while also reviewing evidence for attention biases in eating-disorder patients, restrained eaters and healthy-weight individuals. Another aim was to systematically examine how selective attention for food relates (causally) to eating behaviour. Current empirical evidence on attention bias for food within obese samples, eating-disorder patients, and, even though to a lesser extent, in restrained eaters is contradictory. However, present experimental studies provide relatively consistent evidence that an attention bias for food contributes to subsequent food intake. This review highlights the need to distinguish not only between different (temporal) attention bias components, but also to take different motivations (craving v. worry) and their impact on attentional processing into account. Overall, the current state of research suggests that biased attention could be one important cognitive mechanism by which the food environment tempts us into overeating. PMID:25311212

  9. Worry or craving? A selective review of evidence for food-related attention biases in obese individuals, eating-disorder patients, restrained eaters and healthy samples.

    PubMed

    Werthmann, Jessica; Jansen, Anita; Roefs, Anne

    2015-05-01

    Living in an 'obesogenic' environment poses a serious challenge for weight maintenance. However, many people are able to maintain a healthy weight indicating that not everybody is equally susceptible to the temptations of this food environment. The way in which someone perceives and reacts to food cues, that is, cognitive processes, could underlie differences in susceptibility. An attention bias for food could be such a cognitive factor that contributes to overeating. However, an attention bias for food has also been implicated with restrained eating and eating-disorder symptomatology. The primary aim of the present review was to determine whether an attention bias for food is specifically related to obesity while also reviewing evidence for attention biases in eating-disorder patients, restrained eaters and healthy-weight individuals. Another aim was to systematically examine how selective attention for food relates (causally) to eating behaviour. Current empirical evidence on attention bias for food within obese samples, eating-disorder patients, and, even though to a lesser extent, in restrained eaters is contradictory. However, present experimental studies provide relatively consistent evidence that an attention bias for food contributes to subsequent food intake. This review highlights the need to distinguish not only between different (temporal) attention bias components, but also to take different motivations (craving v. worry) and their impact on attentional processing into account. Overall, the current state of research suggests that biased attention could be one important cognitive mechanism by which the food environment tempts us into overeating.

  10. A small post-translocation energy bias aids nucleotide selection in T7 RNA polymerase transcription.

    PubMed

    Yu, Jin; Oster, George

    2012-02-01

    The RNA polymerase (RNAP) of bacteriophage T7 is a single subunit enzyme that can transcribe DNA to RNA in the absence of additional protein factors. In this work, we present a model of T7 RNAP translocation during elongation. Based on structural information and experimental data from single-molecule force measurements, we show that a small component of facilitated translocation or power stroke coexists with the Brownian-ratchet-driven motions, and plays a crucial role in nucleotide selection at pre-insertion. The facilitated translocation is carried out by the conserved Tyr(639) that moves its side chain into the active site, pushing aside the 3'-end of the RNA, and forming a locally stabilized post-translocation intermediate. Pre-insertion of an incoming nucleotide into this stabilized intermediate state ensures that Tyr(639) closely participates in selecting correct nucleotides. A similar translocation mechanism has been suggested for multi-subunit RNAPs involving the bridge-helix bending. Nevertheless, the bent bridge-helix sterically prohibits nucleotide binding in the post-transolocation intermediate analog; moreover, the analog is not stabilized unless an inhibitory protein factor binds to the enzyme. Using our scheme, we also compared the efficiencies of different strategies for nucleotide selection, and examined effects of facilitated translocation on forward tracking.

  11. Selective attention to food-related stimuli in hunger: are attentional biases specific to emotional and psychopathological states, or are they also found in normal drive states?

    PubMed

    Mogg, K; Bradley, B P; Hyare, H; Lee, S

    1998-02-01

    Previous work has indicated that anxiety disorders and eating disorders are associated with selective processing of stimuli relevant to patients' concerns (e.g. Mathews and MacLeod, 1994; Annual Review of Psychology, 45, 25-50; Channon et al., 1988; British Journal of Clinical Psychology, 27, 259-260). A dot probe task was used to investigate whether attentional biases are also a feature of a normal drive state. Specifically, we examined whether hunger is associated with biases in selective attention and in pre-attentive processes for food-relevant stimuli. Subjects with high levels of hunger showed a greater attentional bias for food-related words presented in a suprathreshold exposure condition (words shown for 500 msec), in comparison with those with low hunger. There was no evidence in the present study of a hunger-related bias in pre-attentive processes (i.e. when words were shown for 14 msec and masked). Results suggest that a non-emotional motivational state, such as hunger, is associated with a bias in certain aspects of information processing, such as selective attention, for stimuli that are relevant to the motivational state. Findings are discussed in relation to recent research into emotion-related cognitive biases.

  12. General trends in selectively driven codon usage biases in the domain archaea.

    PubMed

    Iriarte, Andrés; Jara, Eugenio; Leytón, Lucía; Diana, Leticia; Musto, Héctor

    2014-10-01

    Since the advent of rapid techniques for sequencing DNA in the mid 70's, it became clear that all codons coding for the same amino acid are not used according to neutral expectations. In the last 30 years, several theories were proposed for explaining this fact. However, the most important concepts were the result of analyses carried out in Bacteria, and unicellular and multicellular eukaryotes like mammals (in other words, in two of the three Domains of life). In this communication, we study the main forces that shape codon usage in Archaeae under an evolutionary perspective. This is important because, as known, the orthologous genes related with the informational system in this Domain (replication, transcription and translation) are more similar to eukaryotes than to Bacteria. Our results show that the effect of selection acting at the level of translation is present in the Domain but mainly restricted to only a phylum (Euryarchaeota) and therefore is not as extended as in Bacteria. Besides, we describe the phylogenetic distribution of translational optimal codons and estimate the effect of selection acting at the level of accuracy. Finally, we discuss these results under some peculiarities that characterize this Domain.

  13. Nonmaternal Care's Association With Mother's Parenting Sensitivity: A Case of Self-Selection Bias?

    PubMed

    Nomaguchi, Kei M; Demaris, Alfred

    2013-06-01

    Although attachment theory posits that the use of nonmaternal care undermines quality of mothers' parenting, empirical evidence for this link is inconclusive. Using data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (N = 1,233), the authors examined the associations between nonmaternal care characteristics and maternal sensitivity during the first 3 years of children's lives, with special attention to selection effects and moderation by resource levels. Findings from fixed-effects regression models suggested that, on average, there is little relationship between nonmaternal care characteristics and maternal sensitivity, once selection factors are held constant. Some evidence of moderation effects was found, however. Excellent-quality care is related to more sensitivity for mothers with lower family income. Poor-quality care is related to lower sensitivity for single mothers, but not partnered mothers. In sum, nonmaternal care characteristics do not seem to have as much influence on mothers' parenting as attachment theory claims.

  14. In Darwinian evolution, feedback from natural selection leads to biased mutations.

    PubMed

    Caporale, Lynn Helena; Doyle, John

    2013-12-01

    Natural selection provides feedback through which information about the environment and its recurring challenges is captured, inherited, and accumulated within genomes in the form of variations that contribute to survival. The variation upon which natural selection acts is generally described as "random." Yet evidence has been mounting for decades, from such phenomena as mutation hotspots, horizontal gene transfer, and highly mutable repetitive sequences, that variation is far from the simplifying idealization of random processes as white (uniform in space and time and independent of the environment or context).  This paper focuses on what is known about the generation and control of mutational variation, emphasizing that it is not uniform across the genome or in time, not unstructured with respect to survival, and is neither memoryless nor independent of the (also far from white) environment. We suggest that, as opposed to frequentist methods, Bayesian analysis could capture the evolution of nonuniform probabilities of distinct classes of mutation, and argue not only that the locations, styles, and timing of real mutations are not correctly modeled as generated by a white noise random process, but that such a process would be inconsistent with evolutionary theory.

  15. Codon Usage Patterns in Corynebacterium glutamicum: Mutational Bias, Natural Selection and Amino Acid Conservation.

    PubMed

    Liu, Guiming; Wu, Jinyu; Yang, Huanming; Bao, Qiyu

    2010-01-01

    The alternative synonymous codons in Corynebacterium glutamicum, a well-known bacterium used in industry for the production of amino acid, have been investigated by multivariate analysis. As C. glutamicum is a GC-rich organism, G and C are expected to predominate at the third position of codons. Indeed, overall codon usage analyses have indicated that C and/or G ending codons are predominant in this organism. Through multivariate statistical analysis, apart from mutational selection, we identified three other trends of codon usage variation among the genes. Firstly, the majority of highly expressed genes are scattered towards the positive end of the first axis, whereas the majority of lowly expressed genes are clustered towards the other end of the first axis. Furthermore, the distinct difference in the two sets of genes was that the C ending codons are predominate in putatively highly expressed genes, suggesting that the C ending codons are translationally optimal in this organism. Secondly, the majority of the putatively highly expressed genes have a tendency to locate on the leading strand, which indicates that replicational and transciptional selection might be invoked. Thirdly, highly expressed genes are more conserved than lowly expressed genes by synonymous and nonsynonymous substitutions among orthologous genes fromthe genomes of C. glutamicum and C. diphtheriae. We also analyzed other factors such as the length of genes and hydrophobicity that might influence codon usage and found their contributions to be weak. PMID:20445740

  16. Codon Usage Patterns in Corynebacterium glutamicum: Mutational Bias, Natural Selection and Amino Acid Conservation.

    PubMed

    Liu, Guiming; Wu, Jinyu; Yang, Huanming; Bao, Qiyu

    2010-01-01

    The alternative synonymous codons in Corynebacterium glutamicum, a well-known bacterium used in industry for the production of amino acid, have been investigated by multivariate analysis. As C. glutamicum is a GC-rich organism, G and C are expected to predominate at the third position of codons. Indeed, overall codon usage analyses have indicated that C and/or G ending codons are predominant in this organism. Through multivariate statistical analysis, apart from mutational selection, we identified three other trends of codon usage variation among the genes. Firstly, the majority of highly expressed genes are scattered towards the positive end of the first axis, whereas the majority of lowly expressed genes are clustered towards the other end of the first axis. Furthermore, the distinct difference in the two sets of genes was that the C ending codons are predominate in putatively highly expressed genes, suggesting that the C ending codons are translationally optimal in this organism. Secondly, the majority of the putatively highly expressed genes have a tendency to locate on the leading strand, which indicates that replicational and transciptional selection might be invoked. Thirdly, highly expressed genes are more conserved than lowly expressed genes by synonymous and nonsynonymous substitutions among orthologous genes fromthe genomes of C. glutamicum and C. diphtheriae. We also analyzed other factors such as the length of genes and hydrophobicity that might influence codon usage and found their contributions to be weak.

  17. Nonmaternal Care's Association With Mother's Parenting Sensitivity: A Case of Self-Selection Bias?

    PubMed

    Nomaguchi, Kei M; Demaris, Alfred

    2013-06-01

    Although attachment theory posits that the use of nonmaternal care undermines quality of mothers' parenting, empirical evidence for this link is inconclusive. Using data from the National Institute of Child Health and Human Development Study of Early Child Care and Youth Development (N = 1,233), the authors examined the associations between nonmaternal care characteristics and maternal sensitivity during the first 3 years of children's lives, with special attention to selection effects and moderation by resource levels. Findings from fixed-effects regression models suggested that, on average, there is little relationship between nonmaternal care characteristics and maternal sensitivity, once selection factors are held constant. Some evidence of moderation effects was found, however. Excellent-quality care is related to more sensitivity for mothers with lower family income. Poor-quality care is related to lower sensitivity for single mothers, but not partnered mothers. In sum, nonmaternal care characteristics do not seem to have as much influence on mothers' parenting as attachment theory claims. PMID:23772093

  18. Quasi-distributed and wavelength selective addressing of optical micro-resonators based on long period fiber gratings.

    PubMed

    Farnesi, D; Chiavaioli, F; Baldini, F; Righini, G C; Soria, S; Trono, C; Conti, G Nunzi

    2015-08-10

    A novel all-in-fiber method for coupling light to high-Q silica whispering gallery mode (WGM) optical micro-resonators is presented, which is based on a pair of long period fiber gratings (LPGs) written in the same silica fiber, along with a thick fiber taper (15-18 μm in waist) in between the LPGs. The proposed coupling structure is robust and can be replicated many times along the same fiber simply cascading LPGs with different bands. Typical Q-factors of the order of 10(8) and total coupling efficiency up to 60% were measured collecting the resonances of microspheres or microbubbles at the fiber end. This approach uniquely allows quasi-distributed and wavelength selective addressing of different micro-resonators along the same fiber. PMID:26367967

  19. Selection BIAS: Stereotypes and discrimination related to having a history of cancer.

    PubMed

    Martinez, Larry R; White, Craig D; Shapiro, Jenessa R; Hebl, Michelle R

    2016-01-01

    Although great strides have been made in increasing equality and inclusion in organizations, a number of stigmatized groups are overlooked by diversity initiatives, including people with a history of cancer. To examine the workplace experiences of these individuals in selection contexts, we conducted 3 complementary studies that assess the extent to which cancer is disclosed, the stereotypes associated with cancer in the workplace, and discrimination resulting from these stereotypes. In a pilot study, we surveyed 196 individuals with a history of cancer (across 2 samples) about their workplace disclosure habits. In Study 1, we explored stereotypes related to employees with a history of cancer using the framework outlined by the stereotype content model. In Study 2, we used a field study to assess the experiences of job applicants who indicated they were "cancer survivors" (vs. not) with both formal and interpersonal forms of discrimination. This research shows that cancer is disclosed at relatively high rates (pilot study), those with a history of cancer are stereotyped as being higher in warmth than competence (Study 1), and the stereotypes associated with those who have had cancer result in actual discrimination toward them (Study 2). We discuss the theory behind these findings and aim to inform both science and practice with respect to this growing workplace population. PMID:26121089

  20. Kinematic bias on centrality selection of jet events in pPb collisions at the LHC

    NASA Astrophysics Data System (ADS)

    Armesto, Néstor; Gülhan, Doğa Can; Milhano, José Guilherme

    2015-07-01

    Centrality selection has been observed to have a large effect on jet observables in pPb collisions at the Large Hadron Collider, stronger than that predicted by the nuclear modification of parton densities. We study to which extent simple considerations of energy-momentum conservation which link the hard process with the underlying event that provides the centrality estimator, affect jets observables in such collisions. We develop a simplistic approach that considers first the production of jets in a pp collision as described by PYTHIA. From each pp collision, the value of the energy of the parton from the proton participating in the hard scattering is extracted. Then, the underlying event is generated simulating a pPb collision through HIJING, but with the energy of the proton decreased according to the value extracted in the previous step, and both collisions are added. This model is able to capture the bulk of the centrality effect for central to semicentral collisions, for the two available sets of data: dijets from the CMS Collaboration and single jets from the ATLAS Collaboration. As expected, the model fails for peripheral collisions where very few nucleons from Pb participate.

  1. Selection BIAS: Stereotypes and discrimination related to having a history of cancer.

    PubMed

    Martinez, Larry R; White, Craig D; Shapiro, Jenessa R; Hebl, Michelle R

    2016-01-01

    Although great strides have been made in increasing equality and inclusion in organizations, a number of stigmatized groups are overlooked by diversity initiatives, including people with a history of cancer. To examine the workplace experiences of these individuals in selection contexts, we conducted 3 complementary studies that assess the extent to which cancer is disclosed, the stereotypes associated with cancer in the workplace, and discrimination resulting from these stereotypes. In a pilot study, we surveyed 196 individuals with a history of cancer (across 2 samples) about their workplace disclosure habits. In Study 1, we explored stereotypes related to employees with a history of cancer using the framework outlined by the stereotype content model. In Study 2, we used a field study to assess the experiences of job applicants who indicated they were "cancer survivors" (vs. not) with both formal and interpersonal forms of discrimination. This research shows that cancer is disclosed at relatively high rates (pilot study), those with a history of cancer are stereotyped as being higher in warmth than competence (Study 1), and the stereotypes associated with those who have had cancer result in actual discrimination toward them (Study 2). We discuss the theory behind these findings and aim to inform both science and practice with respect to this growing workplace population.

  2. Highly Predictive Reprogramming of tRNA Modifications Is Linked to Selective Expression of Codon-Biased Genes

    PubMed Central

    2016-01-01

    Cells respond to stress by controlling gene expression at several levels, with little known about the role of translation. Here, we demonstrate a coordinated translational stress response system involving stress-specific reprogramming of tRNA wobble modifications that leads to selective translation of codon-biased mRNAs representing different classes of critical response proteins. In budding yeast exposed to four oxidants and five alkylating agents, tRNA modification patterns accurately distinguished among chemically similar stressors, with 14 modified ribonucleosides forming the basis for a data-driven model that predicts toxicant chemistry with >80% sensitivity and specificity. tRNA modification subpatterns also distinguish SN1 from SN2 alkylating agents, with SN2-induced increases in m3C in tRNA mechanistically linked to selective translation of threonine-rich membrane proteins from genes enriched with ACC and ACT degenerate codons for threonine. These results establish tRNA modifications as predictive biomarkers of exposure and illustrate a novel regulatory mechanism for translational control of cell stress response. PMID:25772370

  3. Making the climate part of the human world: Why addressing beliefs and biases is necessary part of effective climate change education

    NASA Astrophysics Data System (ADS)

    Donner, S. D.

    2009-12-01

    Efforts to raise public awareness and understanding of the social, cultural and economic consequences of climate change often encounter skepticism. The primary causes of this skepticism, whether in the form of a mild rejection of proposed policy responses or an outright rejection of the basic scientific findings, is often cited to be the poor framing of issues by the scientific community, the quality of science education or public science literacy, disinformation campaigns by representatives of the coal and gas industry, individual resistance to behavioral change, and the hyperactive nature of the modern information culture. However, the root cause may be that the weather and climate, and by association climate change, is viewed as independent of the sphere of human influence in ancient and modern societies. In this presentation, I will outline how long-standing human beliefs in the separation between the earth and the sky and the modern framing of climate change as an “environmental” issue are limiting efforts to education the public about the causes, effects and possible response to climate change. First, sociological research in the Pacific Islands (Fiji, Kiribati, Tuvalu) finds strong evidence that beliefs in divine control of the weather and climate limit public acceptance of human-induced climate change. Second, media analysis and polling data from North America supports the role of belief and provides further evidence that climate change is viewed as a threat to an “other” labeled “the environment”, rather than a threat to people or society. The consequences of these mental models of the climate can be an outright reject of scientific theory related to climate change, a milder distrust of climate change predictions, a lack of urgency about mitigation, and an underestimate of the effort required to adapt to climate change. In order to be effective, public education about climate change needs to directly address the two, critical beliefs held by

  4. Efficacy of measures of hygiene in workers sensitised to acid anhydrides and the influence of selection bias on the results

    PubMed Central

    Drexler, H.; Schaller, K. H.; Nielsen, J.; Weber, A.; Weihrauch, M.; Welinder, H.; Skerfving, S.

    1999-01-01

    OBJECTIVES: Organic acid anhydrides are potential sensitisers and cause occupational airway diseases. In an intervention study the efficacy of measures of hygiene at the workplace and possible selection bias were investigated. METHODS: A first investigation with 110 workers exposed to hexahydrophthalic acid anhydride (HHPA) and methyltetrahydrophthalic acid anhydride (MTHPA) was carried out in July 1991. The results (skin prick test, specific serum IgE) showed that 20 people were sensitised, and in a challenge test the clinical relevance of the sensitisation was confirmed in six subjects. In December 1991, the hygiene conditions at the plant were improved. In November 1995 a second investigation of 84 people was performed (anamnesis, skin prick test, specific IgE, spirometry, and ambient and biological monitoring). The 27 people who had left the plant in the meantime were asked their reasons for leaving. RESULTS: The relative risk of people sensitised in 1991 of leaving the plant between 1991 and 1995 was 2.6 (95% confidence interval (95% CI) 1.4 to 4.9) compared with people without any sign of sensitisation. The percentage of people identified as sensitised in 1991, who were still working at the plant and came to the second investigation, was higher than for people without evidence of sensitisation (10/10 v 47/73; p < 0.05). In all the 10 sensitised people in 1991 the findings of the first investigation were confirmed in 1995. The rate of sensitisation in 1995 was 21%. None of the six people employed after 1991 showed evidence of sensitisation. Of the six people with clinically relevant sensitisation confirmed by a challenge test in 1991, five were still at their workplace. From 1991 they were only exposed to MTHPA at a reduced concentration (< 0.5-36 micrograms/m3 in 1995). All of them reported fewer symptoms than in 1991. No signs of bronchial obstruction were detected by spirometry at the workplace. CONCLUSIONS: In cross sectional studies there is a selection

  5. Aversive-bias and stage-selectivity in neurons of the primate amygdala during acquisition, extinction, and overnight retention.

    PubMed

    Livneh, Uri; Paz, Rony

    2012-06-20

    Extensive evidence implicates the amygdala as a major station for acquisition, extinction, and consolidation of emotional memories. Most of this work relies on fear-conditioning in rodents and imaging in humans. Few studies have explored coding of value in the primate amygdala, but the circuitry that underlies extinction and overnight retention remains largely unexplored. We developed a learning paradigm for nonhuman primates (macaca fascicularis) and recorded the activity of single neurons during the different stages of acquisition, extinction, and overnight consolidation of pleasant and aversive tone-odor associations. We find that many neurons become phase-locked to respiratory cycles in a stage-dependent manner, emphasizing the flexibility of amygdala neurons to represent the current state and change their spontaneous activity accordingly. We suggest that these changes can serve to increase neuronal sensitivity to an upcoming event and facilitate learning mechanisms. We further show formation of aversive-bias during the acquisition of associations and during overnight retention, in the sense that neurons preferentially code for the aversive conditioned stimuli, even if they initially homogenously represent value of the reinforcer. Our findings show flexible representations in the primate amygdala during the different cycles of learning and memory, and suggest selective potentiation of aversive information.

  6. Enhanced probing of attentional bias: the independence of anxiety-linked selectivity in attentional engagement with and disengagement from negative information.

    PubMed

    Grafton, Ben; MacLeod, Colin

    2014-01-01

    Cognitive models of anxiety posit that an attentional bias to negative information plays a causal role in elevated anxiety vulnerability and dysfunction. There has been considerable recent interest in determining whether this attentional bias reflects facilitated attentional engagement with and/or impaired attentional disengagement from negative information. We concur with the claim of investigators who have noted that the methodologies previously employed to dissociate engagement and disengagement biases are not optimal for this purpose. In the present study, we employ a novel methodology, the Attentional Response to Distal vs. Proximal Emotional Information (ARDPEI) task, which enables the discrete assessment of these two types of attentional selectivity. The findings demonstrate that facilitated attentional engagement with and impaired attentional disengagement from negative information both characterise elevated anxiety vulnerability. Further, these biases represent distinctive facets of anxiety-linked attentional selectivity. We discuss the potentially differing roles that engagement and disengagement biases may play in the development and/or maintenance of anxiety vulnerability and dysfunction.

  7. Queries for Bias Testing

    NASA Technical Reports Server (NTRS)

    Gordon, Diana F.

    1992-01-01

    Selecting a good bias prior to concept learning can be difficult. Therefore, dynamic bias adjustment is becoming increasingly popular. Current dynamic bias adjustment systems, however, are limited in their ability to identify erroneous assumptions about the relationship between the bias and the target concept. Without proper diagnosis, it is difficult to identify and then remedy faulty assumptions. We have developed an approach that makes these assumptions explicit, actively tests them with queries to an oracle, and adjusts the bias based on the test results.

  8. Intrinsic selection biases of ground-based gravitational wave searches for high-mass black hole-black hole mergers

    SciTech Connect

    O'Shaughnessy, R.; Vaishnav, B.; Healy, J.; Shoemaker, D.

    2010-11-15

    The next generation of ground-based gravitational wave detectors may detect a few mergers of comparable-mass M{approx_equal}100-1000M{sub {center_dot}}[''intermediate-mass'' (IMBH)] spinning black holes. Black hole spin is known to have a significant impact on the orbit, merger signal, and post-merger ringdown of any binary with non-negligible spin. In particular, the detection volume for spinning binaries depends significantly on the component black hole spins. We provide a fit to the single-detector and isotropic-network detection volume versus (total) mass and arbitrary spin for equal-mass binaries. Our analysis assumes matched filtering to all significant available waveform power (up to l=6 available for fitting, but only l{<=}4 significant) estimated by an array of 64 numerical simulations with component spins as large as S{sub 1,2}/M{sup 2{<=}}0.8. We provide a spin-dependent estimate of our uncertainty, up to S{sub 1,2}/M{sup 2{<=}}1. For the initial (advanced) LIGO detector, our fits are reliable for M(set-membership sign)[100,500]M{sub {center_dot}} (M(set-membership sign)[100,1600]M{sub {center_dot}}). In the online version of this article, we also provide fits assuming incomplete information, such as the neglect of higher-order harmonics. We briefly discuss how a strong selection bias towards aligned spins influences the interpretation of future gravitational wave detections of IMBH-IMBH mergers.

  9. The relative age effect in the German Football TID Programme: biases in motor performance diagnostics and effects on single motor abilities and skills in groups of selected players.

    PubMed

    Votteler, Andreas; Höner, Oliver

    2014-01-01

    This study examined the disturbing effects of relative age on the talent identification process in the talent development programme of the German Football Association. The bias in the selection rate was examined via the extent of relative age effects. The bias in motor performance diagnostics was analysed by comparing the motor performance of selected players with normal motor development. The mechanisms underlying the relative age biases in motor performance were examined by modelling the direct and indirect effects of relative age on single motor performance tests for sprint, running agility, dribbling and ball passing and control. Data from 10,130 selected football players from the U12 to U15 age groups were collected in autumn 2010. The birth distribution differed significantly from the reference population with approximately 61% of the players born in the first half of the year. The selection probability was approximately two times higher for players born in the first quarter of the year than for players born in the last quarter. Revised motor performance diagnostics showed better results on average for relatively younger players. Path analysis revealed significant direct and indirect relative age effects for physiologically demanding tests and almost no effects for technically demanding tests. Large sample sizes allowed high resolution in relative age with additional informational content and multivariate modelling of the complex relationships among relative age, physical development and motor performance. The results are discussed on how relative age affects the effectiveness and fairness of talent identification and development processes.

  10. Assessing Bias in Search Engines.

    ERIC Educational Resources Information Center

    Mowshowitz, Abbe; Kawaguchi, Akira

    2002-01-01

    Addresses the measurement of bias in search engines on the Web, defining bias as the balance and representation of items in a collection retrieved from a database for a set of queries. Assesses bias by measuring the deviation from the ideal of the distribution produced by a particular search engine. (Author/LRW)

  11. English Education Today: Selected Addresses Delivered at the NCTE Conference on English Education (Indiana University, March 28-30, 1963).

    ERIC Educational Resources Information Center

    Burton, Dwight L., Ed.

    Thirteen addresses from the 1963 Conference on English Education deal with problems faced by educators responsible for preparing prospective teachers of English. A brief introduction in which Dwight L. Burton affirms that teacher education is a sound blend of liberal arts and professional education precedes Robert C. Pooley's discussion of "The…

  12. Indoor Air Quality: Federal and State Actions To Address the Indoor Air Quality Problems of Selected Buildings.

    ERIC Educational Resources Information Center

    Guerrero, Peter F.

    U.S. House of Representative members requested that the General Accounting Office determine what federal and state actions have been taken in addressing indoor air quality (IAQ) concerns raised in certain school, state, and federal buildings within Vermont, Maryland, and the District of Columbia. This report responds to this request and describes…

  13. Where the Action is; Selected Addresses and Proceedings of the American Industrial Arts Association's Annual Convention (31st, Las Vegas).

    ERIC Educational Resources Information Center

    Taxis, Linda A., Ed.

    Manuscripts of 99 speeches are compiled in book form for general, subject area, and special interest sessions of the convention. Speeches in the subject area and special interest sessions addressed one of the following major topics: (1) Curriculum Development, (2) Inner-City Schools, (3) Instructional Systems, (4) Teacher Education, (5) Vocational…

  14. Biases in Long-term NO2 Averages Inferred from Satellite Observations Due to Cloud Selection Criteria

    NASA Technical Reports Server (NTRS)

    Geddes, Jeffrey A.; Murphy, Jennifer G.; O'Brien, Jason M.; Celarier, Edward A.

    2012-01-01

    Retrievals of atmospheric trace gas column densities from space are compromised by the presence of clouds, requiring most studies to exclude observations with significant cloud fractions in the instrument's field of view. Using NO2 observations at three ground stations representing urban, suburban, and rural environments, and tropospheric vertical column densities measured by the Ozone Monitoring Instrument (OMI) over each site, we show that the observations from space represent monthly averaged ground-level pollutant conditions well (R=0.86) under relatively cloud-free conditions. However, by analyzing the ground-level data and applying the OMI cloud fraction as a filter, we show there is a significant bias in long-term averaged NO2 as a result of removing the data during cloudy conditions. For the ground-based sites considered in this study, excluding observations on days when OMI-derived cloud fractions were greater than 0.2 causes 12:00-14:00 mean summer mixing ratios to be underestimated by 12%+/-6%, 20%+/-7%, and 40%+/-10% on average (+/-1 standard deviation) at the urban, suburban, and rural sites respectively. This bias was investigated in particular at the rural site, a region where pollutant transport is the main source of NO2, and where longterm observations of NOy were also available. Evidence of changing photochemical conditions and a correlation between clear skies and the transport of cleaner air masses play key roles in explaining the bias. The magnitude of a bias is expected to vary from site to site depending on meteorology and proximity to NOx sources, and decreases when longer averaging times of ground station data (e.g. 24-h) are used for the comparison.

  15. Attentional Bias towards Positive Emotion Predicts Stress Resilience.

    PubMed

    Thoern, Hanna A; Grueschow, Marcus; Ehlert, Ulrike; Ruff, Christian C; Kleim, Birgit

    2016-01-01

    There is extensive evidence for an association between an attentional bias towards emotionally negative stimuli and vulnerability to stress-related psychopathology. Less is known about whether selective attention towards emotionally positive stimuli relates to mental health and stress resilience. The current study used a modified Dot Probe task to investigate if individual differences in attentional biases towards either happy or angry emotional stimuli, or an interaction between these biases, are related to self-reported trait stress resilience. In a nonclinical sample (N = 43), we indexed attentional biases as individual differences in reaction time for stimuli preceded by either happy or angry (compared to neutral) face stimuli. Participants with greater attentional bias towards happy faces (but not angry faces) reported higher trait resilience. However, an attentional bias towards angry stimuli moderated this effect: The attentional bias towards happy faces was only predictive for resilience in those individuals who also endorsed an attentional bias towards angry stimuli. An attentional bias towards positive emotional stimuli may thus be a protective factor contributing to stress resilience, specifically in those individuals who also endorse an attentional bias towards negative emotional stimuli. Our findings therefore suggest a novel target for prevention and treatment interventions addressing stress-related psychopathology. PMID:27008475

  16. Attentional Bias towards Positive Emotion Predicts Stress Resilience.

    PubMed

    Thoern, Hanna A; Grueschow, Marcus; Ehlert, Ulrike; Ruff, Christian C; Kleim, Birgit

    2016-01-01

    There is extensive evidence for an association between an attentional bias towards emotionally negative stimuli and vulnerability to stress-related psychopathology. Less is known about whether selective attention towards emotionally positive stimuli relates to mental health and stress resilience. The current study used a modified Dot Probe task to investigate if individual differences in attentional biases towards either happy or angry emotional stimuli, or an interaction between these biases, are related to self-reported trait stress resilience. In a nonclinical sample (N = 43), we indexed attentional biases as individual differences in reaction time for stimuli preceded by either happy or angry (compared to neutral) face stimuli. Participants with greater attentional bias towards happy faces (but not angry faces) reported higher trait resilience. However, an attentional bias towards angry stimuli moderated this effect: The attentional bias towards happy faces was only predictive for resilience in those individuals who also endorsed an attentional bias towards angry stimuli. An attentional bias towards positive emotional stimuli may thus be a protective factor contributing to stress resilience, specifically in those individuals who also endorse an attentional bias towards negative emotional stimuli. Our findings therefore suggest a novel target for prevention and treatment interventions addressing stress-related psychopathology.

  17. Attentional Bias towards Positive Emotion Predicts Stress Resilience

    PubMed Central

    Ehlert, Ulrike; Ruff, Christian C.; Kleim, Birgit

    2016-01-01

    There is extensive evidence for an association between an attentional bias towards emotionally negative stimuli and vulnerability to stress-related psychopathology. Less is known about whether selective attention towards emotionally positive stimuli relates to mental health and stress resilience. The current study used a modified Dot Probe task to investigate if individual differences in attentional biases towards either happy or angry emotional stimuli, or an interaction between these biases, are related to self-reported trait stress resilience. In a nonclinical sample (N = 43), we indexed attentional biases as individual differences in reaction time for stimuli preceded by either happy or angry (compared to neutral) face stimuli. Participants with greater attentional bias towards happy faces (but not angry faces) reported higher trait resilience. However, an attentional bias towards angry stimuli moderated this effect: The attentional bias towards happy faces was only predictive for resilience in those individuals who also endorsed an attentional bias towards angry stimuli. An attentional bias towards positive emotional stimuli may thus be a protective factor contributing to stress resilience, specifically in those individuals who also endorse an attentional bias towards negative emotional stimuli. Our findings therefore suggest a novel target for prevention and treatment interventions addressing stress-related psychopathology. PMID:27008475

  18. The Biases of Optical Line-Ratio Selection for Active Galactic Nuclei and the Intrinsic Relationship between Black Hole Accretion and Galaxy Star Formation

    NASA Astrophysics Data System (ADS)

    Trump, Jonathan R.; Sun, Mouyuan; Zeimann, Gregory R.; Luck, Cuyler; Bridge, Joanna S.; Grier, Catherine J.; Hagen, Alex; Juneau, Stephanie; Montero-Dorta, Antonio; Rosario, David J.; Brandt, W. Niel; Ciardullo, Robin; Schneider, Donald P.

    2015-09-01

    We use 317,000 emission-line galaxies from the Sloan Digital Sky Survey to investigate line-ratio selection of active galactic nuclei (AGNs). In particular, we demonstrate that “star formation (SF) dilution” by H ii regions causes a significant bias against AGN selection in low-mass, blue, star-forming, disk-dominated galaxies. This bias is responsible for the observed preference of AGNs among high-mass, green, moderately star-forming, bulge-dominated hosts. We account for the bias and simulate the intrinsic population of emission-line AGNs using a physically motivated Eddington ratio distribution, intrinsic AGN narrow line region line ratios, a luminosity-dependent {L}{bol}/L[{{O}} {{III}}] bolometric correction, and the observed {M}{BH}-σ relation. These simulations indicate that, in massive ({log}({M}*/{M}⊙ )≳ 10) galaxies, AGN accretion is correlated with specific star formation rate (SFR) but is otherwise uniform with stellar mass. There is some hint of lower black hole occupation in low-mass ({log}({M}*/{M}⊙ )≲ 10) hosts, although our modeling is limited by uncertainties in measuring and interpreting the velocity dispersions of low-mass galaxies. The presence of SF dilution means that AGNs contribute little to the observed strong optical emission lines (e.g., [{{O}} {{III}}] and {{H}}α ) in low-mass and star-forming hosts. However the AGN population recovered by our modeling indicates that feedback by typical (low- to moderate-accretion) low-redshift AGNs has nearly uniform efficiency at all stellar masses, SFRs, and morphologies. Taken together, our characterization of the observational bias and resultant AGN occupation function suggest that AGNs are unlikely to be the dominant source of SF quenching in galaxies, but instead are fueled by the same gas which drives SF activity.

  19. Sexual selection on male size drives the evolution of male-biased sexual size dimorphism via the prolongation of male development.

    PubMed

    Rohner, Patrick T; Blanckenhorn, Wolf U; Puniamoorthy, Nalini

    2016-06-01

    Sexual size dimorphism (SSD) arises when the net effects of natural and sexual selection on body size differ between the sexes. Quantitative SSD variation between taxa is common, but directional intraspecific SSD reversals are rare. We combined micro- and macroevolutionary approaches to study geographic SSD variation in closely related black scavenger flies. Common garden experiments revealed stark intra- and interspecific variation: Sepsis biflexuosa is monomorphic across the Holarctic, while S. cynipsea (only in Europe) consistently exhibits female-biased SSD. Interestingly, S. neocynipsea displays contrasting SSD in Europe (females larger) and North America (males larger), a pattern opposite to the geographic reversal in SSD of S. punctum documented in a previous study. In accordance with the differential equilibrium model for the evolution of SSD, the intensity of sexual selection on male size varied between continents (weaker in Europe), whereas fecundity selection on female body size did not. Subsequent comparative analyses of 49 taxa documented at least six independent origins of male-biased SSD in Sepsidae, which is likely caused by sexual selection on male size and mediated by bimaturism. Therefore, reversals in SSD and the associated changes in larval development might be much more common and rapid and less constrained than currently assumed. PMID:27168489

  20. Community Colleges, Catalysts for Mobility or Engines for Inequality? Addressing Selection Bias in the Estimation of Their Effects on Educational and Occupational Outcomes

    ERIC Educational Resources Information Center

    Gonzalez Canche, Manuel Sacramento

    2012-01-01

    For the last 25 years, research on the effects of community colleges on baccalaureate degree attainment has concluded that community colleges drastically reduce the likelihood of attaining a bachelor's degree compared to the effects of four-year institutions on this likelihood. The thesis of this dissertation is that community colleges have…

  1. Biased Allostery.

    PubMed

    Edelstein, Stuart J; Changeux, Jean-Pierre

    2016-09-01

    G-protein-coupled receptors (GPCRs) constitute a large group of integral membrane proteins that transduce extracellular signals from a wide range of agonists into targeted intracellular responses. Although the responses can vary depending on the category of G-proteins activated by a particular receptor, responses were also found to be triggered by interactions of the receptor with β-arrestins. It was subsequently discovered that for the same receptor molecule (e.g., the β-adrenergic receptor), some agonists have a propensity to specifically favor responses by G-proteins, others by β-arrestins, as has now been extensively studied. This feature of the GPCR system is known as biased agonism and is subject to various interpretations, including agonist-induced conformational change versus selective stabilization of preexisting active conformations. Here, we explore a complete allosteric framework for biased agonism based on alternative preexisting conformations that bind more strongly, but nonexclusively, either G-proteins or β-arrestins. The framework incorporates reciprocal effects among all interacting molecules. As a result, G-proteins and β-arrestins are in steric competition for binding to the cytoplasmic surface of either the G-protein-favoring or β-arrestin-favoring GPCR conformation. Moreover, through linkage relations, the strength of the interactions of G-proteins or β-arrestins with the corresponding active conformation potentiates the apparent affinity for the agonist, effectively equating these two proteins to allosteric modulators. The balance between response alternatives can also be influenced by the physiological concentrations of either G-proteins or β-arrestins, as well as by phosphorylation or interactions with positive or negative allosteric modulators. The nature of the interactions in the simulations presented suggests novel experimental tests to distinguish more fully among alternative mechanisms. PMID:27602718

  2. Case method and casuistry: the problem of bias.

    PubMed

    Kopelman, L M

    1994-03-01

    Case methods of reasoning are persuasive, but we need to address problems of bias in order to use them to reach morally justifiable conclusions. A bias is an unwarranted inclination or a special perspective that disposes us to mistaken or one-sided judgments. The potential for bias arises at each stage of a case method of reasoning including in describing, framing, selecting and comparing of cases and paradigms. A problem of bias occurs because to identify the relevant features for such purposes, we must use general views about what is relevant; but some of our general views are biased, both in the sense of being unwarranted inclinations and in the sense that they are one of many viable perspectives. This reliance upon general views to determine relevancy creates additional difficulties for defenders who maintain that case methods of moral reasoning are not only useful, but more basic, reliable or prior to other forms of moral reasoning. If we cannot identify the case's relevant features and issues independently of our general views or biases, we need further explanation about why a case method or casuistry should be viewed as prior to or more basic or reliable than other forms of moral reasoning. Problems of bias also arise for other methods of reasoning. In medical science, case reviews are regarded as an unreliable way to form generalizations, and methods such as clinical trials are used to address bias.

  3. Mo-containing tetrahedral amorphous carbon deposited by dualfiltered cathodic vacuum arc with selective pulsed bias voltage

    SciTech Connect

    Pasaja, Nitisak; Sansongsiri, Sakon; Anders, Andre; Vilaithong,Thiraphat; Intasiri, Sawate

    2006-09-10

    Metal-containing tetrahedral amorphous carbon films were produced by dual filtered cathodic vacuum arc (FCVA) plasma sources operated in sequential pulsed mode. A negatively pulsed bias was applied to the substrate only when carbon plasma was generated. Films thickness was measured after deposition by profilometry. Glass slides with silver pads were used as substrate for the of the measurement sheet resistance. The microstructure and composition of the films were characterized by Raman spectroscopy and Rutherford backscattering, respectively. It found that the electrical resistivity decreases with an increase of the Mo content, which can be ascribed to an increase of sp2 content and an increase of the sp2 cluster size.

  4. Mo-containing tetrahedral amorphous carbon deposited by dualfiltered cathodic vacuum arc with selective pulsed bias voltage

    SciTech Connect

    Pasaja, Nitisak; Sansongsiri, Sakon; Intasiri, Sawate; Vilaithong, Thiraphat; Anders, Andre

    2007-01-24

    Metal-containing tetrahedral amorphous carbon films wereproduced by dual filtered cathodic vacuum arc plasma sources operatedinsequentially pulsed mode. Negatively pulsed bias was applied to thesubstrate when carbon plasma was generated, whereas it was absentwhen themolybdenum plasma was presented. Film thickness was measured afterdeposition by profilometry. Glass slides with silver padswere used assubstrates for the measurement of the sheet resistance. Themicrostructure and composition of the films were characterizedbyRamanspectroscopy and Rutherford backscattering, respectively. It was foundthat the electrical resistivity decreases with an increaseof the Mocontent, which can be ascribed to an increase of the sp2 content and anincrease of the sp2 cluster size.

  5. Self-controlled case series and misclassification bias induced by case selection from administrative hospital databases: application to febrile convulsions in pediatric vaccine pharmacoepidemiology.

    PubMed

    Quantin, Catherine; Benzenine, Eric; Velten, Michel; Huet, Frédéric; Farrington, C Paddy; Tubert-Bitter, Pascale

    2013-12-15

    Vaccine safety studies are increasingly conducted by using administrative health databases and self-controlled case series designs that are based on cases only. Often, several criteria are available to define the cases, which may yield different positive predictive values, as well as different sensitivities, and therefore different numbers of selected cases. The question then arises as to which is the best case definition. This article proposes new methodology to guide this choice based on the bias of the relative incidence and the power of the test. We apply this methodology in a validation study of 4 nested algorithms for identifying febrile convulsions from the administrative databases of 10 French hospitals. We used a sample of 695 children aged 1 month to 3 years who were hospitalized in 2008-2009 with at least 1 diagnosis code of febrile convulsions. The positive predictive values of the algorithms ranged from 81% to 98%, and their sensitivities were estimated to be 47%-99% in data from 1 large hospital. When applying our proposed methods, the algorithm we selected used a restricted diagnosis code and position on the discharge abstract. These criteria, which resulted in the selection of 502 cases with a positive predictive value of 95%, provided the best compromise between high power and low relative bias.

  6. Bias and precision of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1984

    USGS Publications Warehouse

    Brooks, M.H.; Schroder, L.J.; Willoughby, T.C.

    1987-01-01

    The U.S. Geological Survey operated a blind audit sample program during 1974 to test the effects of the sample handling and shipping procedures used by the National Atmospheric Deposition Program and National Trends Network on the quality of wet deposition data produced by the combined networks. Blind audit samples, which were dilutions of standard reference water samples, were submitted by network site operators to the central analytical laboratory disguised as actual wet deposition samples. Results from the analyses of blind audit samples were used to calculate estimates of analyte bias associated with all network wet deposition samples analyzed in 1984 and to estimate analyte precision. Concentration differences between double blind samples that were submitted to the central analytical laboratory and separate analyses of aliquots of those blind audit samples that had not undergone network sample handling and shipping were used to calculate analyte masses that apparently were added to each blind audit sample by routine network handling and shipping procedures. These calculated masses indicated statistically significant biases for magnesium, sodium , potassium, chloride, and sulfate. Median calculated masses were 41.4 micrograms (ug) for calcium, 14.9 ug for magnesium, 23.3 ug for sodium, 0.7 ug for potassium, 16.5 ug for chloride and 55.3 ug for sulfate. Analyte precision was estimated using two different sets of replicate measures performed by the central analytical laboratory. Estimated standard deviations were similar to those previously reported. (Author 's abstract)

  7. Collection Development and the Psychology of Bias

    ERIC Educational Resources Information Center

    Quinn, Brian

    2012-01-01

    The library literature addressing the role of bias in collection development emphasizes a philosophical approach. It is based on the notion that bias can be controlled by the conscious act of believing in certain values and adhering to a code of ethics. It largely ignores the psychological research on bias, which suggests that bias is a more…

  8. Effects of Acute Dopamine Precusor Depletion on Immediate Reward Selection Bias and Working Memory Depend on Catechol-O-methyltransferase Genotype

    PubMed Central

    Kelm, Mary Katherine; Boettiger, Charlotte A.

    2013-01-01

    Little agreement exists as to acute dopamine (DA) manipulation effects on intertemporal choice in humans. We previously found that catechol-O-methyltransferase (COMT) Val158Met genotype predicts individual differences in immediate reward selection bias among adults. Moreover, we and others have shown that the relationship between COMT genotype and immediate reward bias is inverted in adolescents. No previous pharmacology studies testing DA manipulation effects on intertemporal choice have accounted for COMT genotype, and many have included participants in the adolescent age range (18–21) as adults. Moreover, many studies have included female subjects without strict cycle phase control, although recent evidence demonstrates that cyclic estradiol elevations interact with COMT genotype to affect DA-dependent cognition. These factors may have interacted with DA manipulations in past studies, potentially occluding detection of effects. Therefore, we predicted that among healthy adult males (ages 22–40), frontal DA tone, as indexed by COMT genotype, would interact with acute changes in DA signaling to affect intertemporal choice. In a double-blind, placebo-controlled design, we decreased central DA via administration of an amino acid beverage deficient in the DA precursors, phenylalanine and tyrosine (P/T[−]), and tested effects on immediate reward bias in a delay-discounting (DD) task and working memory (WM) in an n-back task. We found no main effect of beverage on DD or WM performance, but did find significant beverage*genotype effects. These results suggest that the effect of DA manipulations on DD depends on individual differences in frontal DA tone, which may have impeded some past efforts to characterize DA’s role in immediate reward bias in humans. PMID:23937688

  9. Selection bias in dynamically-measured super-massive black hole samples: its consequences and the quest for the most fundamental relation

    NASA Astrophysics Data System (ADS)

    Shankar, Francesco; Bernardi, M.; Sheth, R. K.; Weinberg, D. H.; Miralda-Escudé, J.; Ferrarese, L.; Graham, A.; Sesana, A.; Lapi, A.; Marconi, A.; Allevato, V.; Savorgnan, G.; Laesker, R.

    2016-08-01

    We compare the set of local galaxies having dynamically measured black holes with a large, unbiased sample of galaxies extracted from the Sloan Digital Sky Survey. We confirm earlier work showing that the majority of black hole hosts have significantly higher velocity dispersions sigma than local galaxies of similar stellar mass. We use Monte-Carlo simulations to illustrate the effect on black hole scaling relations if this bias arises from the requirement that the black hole sphere of influence must be resolved to measure black hole masses with spatially resolved kinematics. We find that this selection effect artificially increases the normalization of the Mbh-sigma relation by a factor of at least ~3; the bias for the Mbh-Mstar relation is even larger. Our Monte Carlo simulations and analysis of the residuals from scaling relations both indicate that sigma is more fundamental than Mstar or effective radius. In particular, the Mbh-Mstar relation is mostly a consequence of the Mbh-sigma and sigma-Mstar relations, and is heavily biased by up to a factor of 50 at small masses. This helps resolve the discrepancy between dynamically-based black hole-galaxy scaling relations versus those of active galaxies. Our simulations also disfavour broad distributions of black hole masses at fixed sigma. Correcting for this bias suggests that the calibration factor used to estimate black hole masses in active galaxies should be reduced to values of fvir~1. Black hole mass densities should also be proportionally smaller, perhaps implying significantly higher radiative efficiencies/black hole spins. Reducing black hole masses also reduces the gravitational wave signal expected from black hole mergers.

  10. A Virtual Observatory Census to Address Dwarfs Origins (AVOCADO). I. Science goals, sample selection, and analysis tools

    NASA Astrophysics Data System (ADS)

    Sánchez-Janssen, R.; Amorín, R.; García-Vargas, M.; Gomes, J. M.; Huertas-Company, M.; Jiménez-Esteban, F.; Mollá, M.; Papaderos, P.; Pérez-Montero, E.; Rodrigo, C.; Sánchez Almeida, J.; Solano, E.

    2013-06-01

    Context. Even though they are by far the most abundant of all galaxy types, the detailed properties of dwarf galaxies are still only poorly characterised - especially because of the observational challenge that their intrinsic faintness and weak clustering properties represent. Aims: AVOCADO aims at establishing firm conclusions on the formation and evolution of dwarf galaxies by constructing and analysing a homogeneous, multiwavelength dataset for a statistically significant sample of approximately 6500 nearby dwarfs (Mi - 5 log h100 > - 18 mag). The sample is selected to lie within the 20 < D < 60 h100-1 Mpc volume covered by the SDSS-DR7 footprint, and is thus volume-limited for Mi - 5 log h100 < -16 mag dwarfs - but includes ≈1500 fainter systems. We will investigate the roles of mass and environment in determining the current properties of the different dwarf morphological types - including their structure, their star formation activity, their chemical enrichment history, and a breakdown of their stellar, dust, and gas content. Methods: We present the sample selection criteria and describe the suite of analysis tools, some of them developed in the framework of the Virtual Observatory. We use optical spectra and UV-to-NIR imaging of the dwarf sample to derive star formation rates, stellar masses, ages, and metallicities - which are supplemented with structural parameters that are used to classify them morphologically. This unique dataset, coupled with a detailed characterisation of each dwarf's environment, allows for a fully comprehensive investigation of their origins and enables us to track the (potential) evolutionary paths between the different dwarf types. Results: We characterise the local environment of all dwarfs in our sample, paying special attention to trends with current star formation activity. We find that virtually all quiescent dwarfs are located in the vicinity (projected distances ≲ 1.5 h100-1 Mpc) of ≳ L∗ companions, consistent with

  11. Understanding our love affair with p-chlorophenyl: present day implications from historical biases of reagent selection.

    PubMed

    Brown, Dean G; Gagnon, Moriah M; Boström, Jonas

    2015-03-12

    We report here an unexpectedly strong preference toward para substitution in phenyl rings within drug discovery programs. A population analysis of aromatic rings in various drug databases demonstrated that para substitution is favored over meta and ortho regioisomers, with p-chlorophenyl (p-ClPh) being one of the most predominant examples. We speculate that the frequency of p-ClPh is traced back to historical models of medicinal chemistry where para-substituted regioisomers were perhaps more easily accessed, and further reinforced by Topliss in 1972 that if Ph was active, the p-ClPh should be made because of ease of synthesis and hydrophobicity driven potency effects. On the basis of our analysis, the para bias has become useful conventional wisdom but perhaps so much so that a perception has been created that druglike space favors a linear aromatic structure. It is hoped this analysis will catalyze a new look at design of reagent databases and screening collections.

  12. Viewpoint: A challenge to academic health centers and the National Institutes of Health to prevent unintended gender bias in the selection of clinical and translational science award leaders.

    PubMed

    Carnes, Molly; Bland, Carole

    2007-02-01

    In controlled studies, both men and women preferentially select men over women for leadership positions, even when credentials are identical and despite field studies demonstrating women's equivalent or slightly better leadership effectiveness. The assumption that men will make better leaders than women is attributed to the pervasive existence of unconscious stereotypes that characterize both men and leaders as agentic or action oriented and women as dependent. The Clinical and Translational Science Award (CTSA) from the National Institutes of Health (NIH) Roadmap is a novel, prestigious award that will place considerable power in the hands of one principal investigator-conditions that predict activation of bias in favor of selecting male leaders. The authors review research supporting this assertion. To mitigate the impact of this bias and broaden the pool of potential leaders for this transformative initiative, the authors offer the following suggestions. To academic health centers they suggest (1) internal search committees comprised of at least 35% women that establish a priori the desired qualities for the CTSA leader and broadly solicit applicants, (2) explicit specification of the full range of desirable skills of a CTSA leader, and (3) systematic efforts to increase awareness of the negative impact of unconscious gender bias on women's advancement. To the NIH they suggest (1) the new multiple principal investigator rule for the CTSA program, (2) a statement in the request for applications (RFA) encouraging diversity among principal investigators, (3) repetition in the RFA of the public NIH statement of the importance of work life balance for young investigators, and (4) constitution of study sections with at least 35% women. PMID:17264704

  13. Viewpoint: A challenge to academic health centers and the National Institutes of Health to prevent unintended gender bias in the selection of clinical and translational science award leaders.

    PubMed

    Carnes, Molly; Bland, Carole

    2007-02-01

    In controlled studies, both men and women preferentially select men over women for leadership positions, even when credentials are identical and despite field studies demonstrating women's equivalent or slightly better leadership effectiveness. The assumption that men will make better leaders than women is attributed to the pervasive existence of unconscious stereotypes that characterize both men and leaders as agentic or action oriented and women as dependent. The Clinical and Translational Science Award (CTSA) from the National Institutes of Health (NIH) Roadmap is a novel, prestigious award that will place considerable power in the hands of one principal investigator-conditions that predict activation of bias in favor of selecting male leaders. The authors review research supporting this assertion. To mitigate the impact of this bias and broaden the pool of potential leaders for this transformative initiative, the authors offer the following suggestions. To academic health centers they suggest (1) internal search committees comprised of at least 35% women that establish a priori the desired qualities for the CTSA leader and broadly solicit applicants, (2) explicit specification of the full range of desirable skills of a CTSA leader, and (3) systematic efforts to increase awareness of the negative impact of unconscious gender bias on women's advancement. To the NIH they suggest (1) the new multiple principal investigator rule for the CTSA program, (2) a statement in the request for applications (RFA) encouraging diversity among principal investigators, (3) repetition in the RFA of the public NIH statement of the importance of work life balance for young investigators, and (4) constitution of study sections with at least 35% women.

  14. Potential self-selection bias in a nested case-control study on indoor environmental factors and their association with asthma and allergic symptoms among pre-school children.

    PubMed

    Bornehag, Carl-Gustaf; Sundell, Jan; Sigsgaard, Torben; Janson, Staffan

    2006-01-01

    Selection bias means a systematic difference between the characteristics of selected and non-selected individuals in epidemiological studies. Such bias may be introduced if participants select themselves for a study. The present study aims at identifying differences in family characteristics, including health, building characteristics of the home, and socioeconomic factors between participating and non-participating families in a nested case-control study on asthma and allergy among children. Information was collected in a baseline questionnaire to the parents of 14,077 children aged 1-6 years in a first step. In a second step 2,156 of the children were invited to participate in a case-control study. Of these, 198 cases and 202 controls were finally selected. For identifying potential selection bias, information concerning all invited families in the case-control study was obtained from the baseline questionnaire. Results show that there are several possible biases due to self-selection involved in an extensive study on the impact of the home environment on asthma and allergy among children. Factors associated with participating were high socioeconomic status of the family, more health problems in the case families, and health-related lifestyle factors, such as non-smoking parents. The overall conclusion of this study is that there are selection biases involved in studies that need close cooperation with the families involved. One solution to this problem is stratification, i.e. investigating associations between exposures and health in the same socioeconomic strata. PMID:16990165

  15. Introduction to Unconscious Bias

    NASA Astrophysics Data System (ADS)

    Schmelz, Joan T.

    2010-05-01

    We all have biases, and we are (for the most part) unaware of them. In general, men and women BOTH unconsciously devalue the contributions of women. This can have a detrimental effect on grant proposals, job applications, and performance reviews. Sociology is way ahead of astronomy in these studies. When evaluating identical application packages, male and female University psychology professors preferred 2:1 to hire "Brian” over "Karen” as an assistant professor. When evaluating a more experienced record (at the point of promotion to tenure), reservations were expressed four times more often when the name was female. This unconscious bias has a repeated negative effect on Karen's career. This talk will introduce the concept of unconscious bias and also give recommendations on how to address it using an example for a faculty search committee. The process of eliminating unconscious bias begins with awareness, then moves to policy and practice, and ends with accountability.

  16. Estimating the “Impact” of Out-of-Home Placement on Child Well-Being: Approaching the Problem of Selection Bias

    PubMed Central

    Berger, Lawrence M.; Bruch, Sarah K.; Johnson, Elizabeth I.; James, Sigrid; Rubin, David

    2010-01-01

    This study used data on 2,453 children age 4 to 17 from the National Survey of Child and Adolescent Well-Being and 5 analytic methods that adjust for selection factors to estimate the impact of out-of-home placement on children's cognitive skills and behavior problems. Methods included ordinary least squares (OLS) regressions and residualized change, simple change, difference-in-difference, and fixed effects models. Models were estimated using the full sample and a matched sample generated by propensity scoring. Although results from the unmatched OLS and residualized change models suggested that out-of-home placement is associated with increased child behavior problems, estimates from models that more rigorously adjust for selection bias indicated that placement has little effect on children's cognitive skills or behavior problems. PMID:19930356

  17. Isoproterenol Acts as a Biased Agonist of the Alpha-1A-Adrenoceptor that Selectively Activates the MAPK/ERK Pathway

    PubMed Central

    Copik, Alicja. J.; Baldys, Aleksander; Nguyen, Khanh; Sahdeo, Sunil; Ho, Hoangdung; Kosaka, Alan; Dietrich, Paul J.; Fitch, Bill; Raymond, John R.; Ford, Anthony P. D. W.; Button, Donald; Milla, Marcos E.

    2015-01-01

    The α1A-AR is thought to couple predominantly to the Gαq/PLC pathway and lead to phosphoinositide hydrolysis and calcium mobilization, although certain agonists acting at this receptor have been reported to trigger activation of arachidonic acid formation and MAPK pathways. For several G protein-coupled receptors (GPCRs) agonists can manifest a bias for activation of particular effector signaling output, i.e. not all agonists of a given GPCR generate responses through utilization of the same signaling cascade(s). Previous work with Gαq coupling-defective variants of α1A-AR, as well as a combination of Ca2+ channel blockers, uncovered cross-talk between α1A-AR and β2-AR that leads to potentiation of a Gαq-independent signaling cascade in response to α1A-AR activation. We hypothesized that molecules exist that act as biased agonists to selectively activate this pathway. In this report, isoproterenol (Iso), typically viewed as β-AR-selective agonist, was examined with respect to activation of α1A-AR. α1A-AR selective antagonists were used to specifically block Iso evoked signaling in different cellular backgrounds and confirm its action at α1A-AR. Iso induced signaling at α1A-AR was further interrogated by probing steps along the Gαq /PLC, Gαs and MAPK/ERK pathways. In HEK-293/EBNA cells transiently transduced with α1A-AR, and CHO_α1A-AR stable cells, Iso evoked low potency ERK activity as well as Ca2+ mobilization that could be blocked by α1A-AR selective antagonists. The kinetics of Iso induced Ca2+ transients differed from typical Gαq- mediated Ca2+ mobilization, lacking both the fast IP3R mediated response and the sustained phase of Ca2+ re-entry. Moreover, no inositol phosphate (IP) accumulation could be detected in either cell line after stimulation with Iso, but activation was accompanied by receptor internalization. Data are presented that indicate that Iso represents a novel type of α1A-AR partial agonist with signaling bias toward MAPK

  18. Growth differences and competition between Listeria monocytogenes strains determine their predominance on ham slices and lead to bias during selective enrichment with the ISO protocol.

    PubMed

    Zilelidou, Evangelia; Manthou, Evanthia; Skandamis, Panagiotis

    2016-10-17

    Listeria monocytogenes strains are widespread in the environment where they live well mixed, often resulting in multiple strains contaminating a single food sample. The occurrence of different strains in the same food might trigger strain competition, contributing to uneven growth of strains in food and to bias during selective procedures. We tested the growth of seven L. monocytogenes strains (C5, 6179, ScottA, PL24, PL25, PL26, PL27) on ham slices and on nutrient-rich agar at 10°C, singly and in combinations. Strains were made resistant to different antibiotics for their selective enumeration. In addition, growth of single strains (axenic culture) and competition between strains in xenic cultures of two strains was evaluated in enrichment broth and on selective agar. According to ISO 11290-1:1996/Amd 1:2004 standard protocol for detection of L. monocytogenes, two enrichment steps both followed by streaking on ALOA were performed. Strain cultures were directly added in the enrichment broth or used to inoculate minced beef and sliced hams which were then mixed with enrichment broth. 180-360 colonies were used to determine the relative percentage of each strain recovered on plates per enrichment step. The data showed a significant impact of co-cultivation on the growth of six out of seven strains on ham and a bias towards certain strains during selective enrichment. Competition was manifested by: (i) cessation of growth for the outcompeted strain when the dominant strain reached stationary phase, (ii) reduction of growth rates or (iii) total suppression of growth (both on ham and in enrichment broth or ALOA). Outgrowth of strains by their competitors on ALOA resulted in limited to no recovery, with the outcompeting strain accounting for up to 100% of the total recovered colonies. The observed bias was associated with the enrichment conditions (i.e. food type added to the enrichment broth) and the strain-combination. The outcome of growth competition on food or

  19. Analysis of threats to research validity introduced by audio recording clinic visits: Selection bias, Hawthorne effect, both, or neither?

    PubMed Central

    Henry, Stephen G.; Jerant, Anthony; Iosif, Ana-Maria; Feldman, Mitchell D.; Cipri, Camille; Kravitz, Richard L.

    2015-01-01

    Objective To identify factors associated with participant consent to record visits; to estimate effects of recording on patient-clinician interactions Methods Secondary analysis of data from a randomized trial studying communication about depression; participants were asked for optional consent to audio record study visits. Multiple logistic regression was used to model likelihood of patient and clinician consent. Multivariable regression and propensity score analyses were used to estimate effects of audio recording on 6 dependent variables: discussion of depressive symptoms, preventive health, and depression diagnosis; depression treatment recommendations; visit length; visit difficulty. Results Of 867 visits involving 135 primary care clinicians, 39% were recorded. For clinicians, only working in academic settings (P=0.003) and having worked longer at their current practice (P=0.02) were associated with increased likelihood of consent. For patients, white race (P=0.002) and diabetes (P=0.03) were associated with increased likelihood of consent. Neither multivariable regression nor propensity score analyses revealed any significant effects of recording on the variables examined. Conclusion Few clinician or patient characteristics were significantly associated with consent. Audio recording had no significant effect on any dependent variables. Practice Implications Benefits of recording clinic visits likely outweigh the risks of bias in this setting. PMID:25837372

  20. Infection Rate by Trypanosoma cruzi and Biased Vertebrate Host Selection in the Triatoma dimidiata (Hemiptera: Reduvidae) Species Complex.

    PubMed

    Ramirez-Sierra, M J; Dumonteil, E

    2016-01-01

    Chagas disease is a vector-borne disease, caused by the protozoan parasite Trypanosoma cruzi and transmitted by hematophagous insects. Triatoma dimidiata (Hemiptera: Reduvidae (Latreille 1811)) is one of the main vectors, and recent molecular studies indicate that it is a species complex, with potentially different vectorial competences. We investigated the differences in natural T. cruzi infection rate within T. dimidiata complex in Yucatan, Mexico. ITS-2 hybrid bugs had a twofold higher infection rate than ITS-2 Groups 2 and 3 bugs, and this pattern was consistent over time and in several villages. To test if T. dimidiata ITS-2 hybrid bugs could feed more frequently on T. cruzi-infected hosts, we evaluated their host-seeking behavior in a dual-choice chamber. Group 2 and 3 bugs were equally attracted to T. cruzi-infected or uninfected mice. On the contrary, ITS-2 hybrid bugs reached three times more frequently the T. cruzi-infected mouse, compared to the uninfected one, indicating a significant bias toward an infected host. This behavior may explain in part their higher natural infection rate. Further studies should explore the complex and unique interactions among T. cruzi, triatomines vectors, and mammalian hosts, as this may led to new strategies to interfere with transmission cycles and improve Chagas disease control.

  1. Initial identification & selection bias versus the eventual confirmation of talent: evidence for the benefits of a rocky road?

    PubMed

    McCarthy, Neil; Collins, Dave

    2014-01-01

    The relative age effect (RAE), whereby earlier birthdate children within a selection year are more commonly selected as talented, has been highlighted in the literature. As a consequence, these young athletes get into specialised training earlier and in greater numbers, leading (it is suggested) to a disproportionate opportunity for success. However, this disproportionality seems not to be manifest in senior teams. Accordingly, we examine the identification and conversion rates for academy rugby players, examining a sample of all players passing into and either graduating, or being dismissed from, a major English rugby academy. Data demonstrated a reversal of the RAE "benefit", whereby late-birth players were less likely to be selected, but more likely to achieve senior professional status. Possible reasons are explored and, on the basis of our data, we propose a psychologically based explanation of greater "growth" due to additional challenge experienced by these initially disadvantaged younger players.

  2. Without Bias? How Selected Employee Publications Depict the Roles of Women and Men within the Corporate Structure.

    ERIC Educational Resources Information Center

    Fleener, Nickieann

    A study examined how presentation of men and women by selected internal business publications changed from 1978 to 1982. A visual content analysis of three major industry publications was conducted. The total number of individuals shown in the 22 magazines studied was 1,551. Of these individuals, 83% were male and 17% were female. After…

  3. Estimating the "Impact" of Out-of-Home Placement on Child Well-Being: Approaching the Problem of Selection Bias

    ERIC Educational Resources Information Center

    Berger, Lawrence M.; Bruch, Sarah K.; Johnson, Elizabeth I.; James, Sigrid; Rubin, David

    2009-01-01

    This study used data on 2,453 children aged 4-17 from the National Survey of Child and Adolescent Well-Being and 5 analytic methods that adjust for selection factors to estimate the impact of out-of-home placement on children's cognitive skills and behavior problems. Methods included ordinary least squares (OLS) regressions and residualized…

  4. Selective enrichment media bias the types of Salmonella enterica strains isolated from mixed strain cultures and complex enrichment broths.

    PubMed

    Gorski, Lisa

    2012-01-01

    For foodborne outbreak investigations it can be difficult to isolate the relevant strain from food and/or environmental sources. If the sample is contaminated by more than one strain of the pathogen the relevant strain might be missed. In this study mixed cultures of Salmonella enterica were grown in one set of standard enrichment media to see if culture bias patterns emerged. Nineteen strains representing four serogroups and ten serotypes were compared in four-strain mixtures in Salmonella-only and in cattle fecal culture enrichment backgrounds using Salmonella enrichment media. One or more strain(s) emerged as dominant in each mixture. No serotype was most fit, but strains of serogroups C2 and E were more likely to dominate enrichment culture mixtures than strains of serogroups B or C1. Different versions of Rappaport-Vassiliadis (RV) medium gave different patterns of strain dominance in both Salmonella-only and fecal enrichment culture backgrounds. The fittest strains belonged to serogroups C1, C2, and E, and included strains of S. Infantis, S. Thompson S. Newport, S. 6,8:d:-, and S. Give. Strains of serogroup B, which included serotypes often seen in outbreaks such as S. Typhimurium, S. Saintpaul, and S. Schwarzengrund were less likely to emerge as dominant strains in the mixtures when using standard RV as part of the enrichment. Using a more nutrient-rich version of RV as part of the protocol led to a different pattern of strains emerging, however some were still present in very low numbers in the resulting population. These results indicate that outbreak investigations of food and/or other environmental samples should include multiple enrichment protocols to ensure isolation of target strains of Salmonella.

  5. Optimization of an extraction protocol for organic matter from soils and sediments using high resolution mass spectrometry: selectivity and biases

    NASA Astrophysics Data System (ADS)

    Chu, R. K.; Tfaily, M. M.; Tolic, N.; Kyle, J. E.; Robinson, E. R.; Hess, N. J.; Paša-Tolić, L.

    2015-12-01

    Soil organic matter (SOM) is a complex mixture of above and belowground plant litter and microbial residues, and is a key reservoir for carbon (C) and nutrient biogeochemical cycling in different ecosystems. A limited understanding of the molecular composition of SOM prohibits the ability to routinely decipher chemical processes within soil and predict how terrestrial C fluxes will response to changing climatic conditions. Here, we present that the choice of solvent can be used to selectively extract different compositional fractions from SOM to either target a specific class of compounds or gain a better understanding of the entire composition of the soil sample using 12T Fourier transform ion cyclotron resonance mass spectrometry. Specifically, we found that hexane and chloroform were selective for lipid-like compounds with very low O:C ratios; water was selective for carbohydrates with high O:C ratios; acetonitrile preferentially extracts lignin, condensed structures, and tannin polyphenolic compounds with O:C > 0.5; methanol has higher selectivity towards lignin and lipid compounds characterized with relatively low O:C < 0.5. Hexane, chloroform, methanol, acetonitrile and water increase the number and types of organic molecules extracted from soil for a broader range of chemically diverse soil types. Since each solvent extracts a selective group of compounds, using a suite of solvents with varying polarity for analysis results in more comprehensive representation of the diversity of organic molecules present in soil and a better representation of the whole spectrum of available substrates for microorganisms. Moreover, we have developed a sequential extraction protocol that permits sampling diverse classes of organic compounds while minimizing ionization competition during ESI while increasing sample throughput and decreasing sample volume. This allowed us to hypothesize about possible chemical reactions relating classes of organic molecules that reflect abiotic

  6. A DIRECT MEASUREMENT OF THE LINEAR BIAS OF MID-INFRARED-SELECTED QUASARS AT z ≈ 1 USING COSMIC MICROWAVE BACKGROUND LENSING

    SciTech Connect

    Geach, J. E.; Hickox, R. C.; Hainline, K. N.; Bleem, L. E.; Benson, B. A.; Bhattacharya, S.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T.; Brodwin, M.; Holder, G. P.; De Haan, T.; Dobbs, M. A.; Dudley, J.; Aird, K. A.; Cho, H.-M.; George, E. M.; Holzapfel, W. L.; Halverson, N. W.; and others

    2013-10-20

    We measure the cross-power spectrum of the projected mass density as traced by the convergence of the cosmic microwave background lensing field from the South Pole Telescope (SPT) and a sample of Type 1 and 2 (unobscured and obscured) quasars at (z) ∼ 1 selected with the Wide-field Infrared Survey Explorer, over 2500 deg{sup 2}. The cross-power spectrum is detected at ≈7σ, and we measure a linear bias b = 1.61 ± 0.22, consistent with clustering analyses. Using an independent lensing map, derived from Planck observations, to measure the cross-spectrum, we find excellent agreement with the SPT analysis. The bias of the combined sample of Type 1 and 2 quasars determined in this work is similar to that previously determined for Type 1 quasars alone; we conclude that obscured and unobscured quasars trace the matter field in a similar way. This result has implications for our understanding of quasar unification and evolution schemes.

  7. Addressing Concerns.

    ERIC Educational Resources Information Center

    Cronin, Greg; Helmig, Mary; Kaplan, Bill; Kosch, Sharon

    2002-01-01

    Four camp directors discuss how the September 11 tragedy and current world events will affect their camps. They describe how they are addressing safety concerns, working with parents, cooperating with outside agencies, hiring and screening international staff, and revising emergency plans. Camps must continue to offer community and support to…

  8. Addressing healthcare.

    PubMed

    Daly, Rich

    2013-02-11

    Though President Barack Obama has rarely made healthcare references in his State of the Union addresses, health policy experts are hoping he changes that strategy this year. "The question is: Will he say anything? You would hope that he would, given that that was the major issue he started his presidency with," says Dr. James Weinstein, left, of the Dartmouth-Hitchcock health system. PMID:23487896

  9. Methodological factors in determining rates of dementia in TIA and stroke: (I) impact of baseline selection bias

    PubMed Central

    Pendlebury, Sarah T; Chen, Ping-jen; Bull, Linda; Silver, Louise; Mehta, Ziyah; Rothwell, Peter M

    2015-01-01

    Background and Purpose Many previous studies on dementia in stroke have restrictive inclusion criteria which may result in under-estimation of dementia rates. We undertook a large prospective population-based study of all TIA and stroke to determine the impact of study entry criteria on measured rates of pre- and post-event dementia. Methods All patients with acute TIA or stroke from a defined population of 92 728 are referred from primary care or at hospital admission to the Oxford Vascular Study (2002-2007) and have baseline clinical and cognitive assessment and follow-up. We examined the impact of early death, other non-availability, and commonly-used selection criteria, on measured rates of dementia. Results Among 1236 patients (mean age/sd 75.2/12.1 years, 582 male, 403 TIA), 139 died or were otherwise unavailable for baseline assessment, 224 were dysphasic, 319 had prior dependency, 425 had co-morbidity, 512 were aged ≥80 years and 502 were hospitalised. Pre-event dementia was threefold higher in patients dying pre-ascertainment (10/47, 21%) and twice as high in other non-assessed (14/92,15%) vs assessed patients (69/1097, 6%; p=0.0006 and p=0.002) and was several-fold higher in those with prior functional impairment (24% vs 3%,p<0.0001), age>80 years (13% vs 3%,p<0.0001), dysphasia (11% vs 7%,p<0.0001) and co-morbidity (10% vs 6%,p=0.04). Findings for post-event dementia were similar: prior functional impairment (40% vs 13%,p<0.0001), age>80 years (28% vs 10%,p<0.0001), dysphasia (22% vs 15%,p=0.02) and co-morbidity (25% vs 15%,p=0.005). Conclusions Exclusion of patients unavailable for assessment, and other widely used selection criteria, results in underestimation of the measured rate of dementia associated with TIA and stroke. PMID:25657179

  10. Tight control of light trapping in surface addressable photonic crystal membranes: application to spectrally and spatially selective optical devices (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Letartre, Xavier; Blanchard, Cédric; Grillet, Christian; Jamois, Cécile; Leclercq, Jean-Louis; Viktorovitch, Pierre

    2016-04-01

    Surface addressable Photonic Crystal Membranes (PCM) are 1D or 2D photonic crystals formed in a slab waveguides where Bloch modes located above the light line are exploited. These modes are responsible for resonances in the reflection spectrum whose bandwidth can be adjusted at will. These resonances result from the coupling between a guided mode of the membrane and a free-space mode through the pattern of the photonic crystal. If broadband, these structures represent an ideal mirror to form compact vertical microcavity with 3D confinement of photons and polarization selectivity. Among numerous devices, low threshold VCSELs with remarkable and tunable modal properties have been demonstrated. Narrow band PCMs (or high Q resonators) have also been extensively used for surface addressable optoelectronic devices where an active material is embedded into the membrane, leading to the demonstration of low threshold surface emitting lasers, nonlinear bistables, optical traps... In this presentation, we will describe the main physical rules which govern the lifetime of photons in these resonant modes. More specifically, it will be emphasized that the Q factor of the PCM is determined, to the first order, by the integral overlap between the electromagnetic field distributions of the guided and free space modes and of the dielectric periodic perturbation which is applied to the homogeneous membrane to get the photonic crystal. It turns out that the symmetries of these distributions are of prime importance for the strength of the resonance. It will be shown that, by molding in-plane or vertical symmetries of Bloch modes, spectrally and spatially selective light absorbers or emitters can be designed. First proof of concept devices will be also presented.

  11. The Protective Effect of Low-Dose Aspirin against Colorectal Cancer Is Unlikely Explained by Selection Bias: Results from Three Different Study Designs in Clinical Practice

    PubMed Central

    Cea Soriano, Lucía; Soriano-Gabarró, Montse; García Rodríguez, Luis A.

    2016-01-01

    Background We conducted three differently designed nested case–control studies to evaluate whether the protective effect of low-dose aspirin against colorectal cancer (CRC) is explained by selection bias. Methods Using a large validated UK primary care database, we followed different cohorts of patients, who varied in their demographic and clinical characteristics, to identify first ever cases of CRC. In Studies 1 and 2, two cohorts were followed, i) new users of low-dose aspirin at start of follow-up (N = 170,336 in Study 1, N = 171,527 in Study 2) and either ii) non-users of low-dose aspirin (Study 1, N = 170,336) or new users of paracetamol (Study 2, N = 149,597) at start of follow-up. In Study 3 a single cohort of individuals näive to low-dose aspirin at the start of observation was followed. Controls were selected using incidence sampling and logistic regression used to obtain an unbiased estimate of the incidence rate ratio (RR) with 95% confidence intervals (CIs). Low-dose aspirin exposure was analyzed ‘as-treated’ before the index date (CRC date for cases, random date for controls). Results In the three studies, median (maximum) follow-up was 5.1 (12), 5.8 (12) and 7.5 (13) years, respectively. 3033 incident CRC cases were identified in Study 1, 3174 in Study 2, and 12,333 in Study 3. Current use of low-dose aspirin was associated with a significantly reduced risk of 34%, 29% and 31% in the three studies, respectively; corresponding RRs (95% CIs) were 0.66 (0.60–0.73), 0.71 (0.63–0.80) and 0.69 (0.64–0.74). In each study, significantly reduced risks of CRC were seen when low-dose aspirin was used for primary or secondary cardiovascular disease prevention, in both sexes, and across all age groups evaluated. Conclusion Low-dose aspirin is associated with a significantly reduced risk of CRC. The consistency of our findings across different studies makes selection bias an unlikely explanation. PMID:27428004

  12. Assessment of selection bias in a health survey of children and families – the IDEFICS Sweden-study

    PubMed Central

    2013-01-01

    .47) followed by parents having high education OR 1.80, 95% CI (1.02-3.16) and being married or co-habiting OR 1.75 95% CI (1.38-2.23). Conclusion Families with single parenthood, foreign background, low education and income were underrepresented in the IDEFICS Sweden study. BMI at inclusion had no selection effect, but developing obesity was significantly greater among referents. PMID:23634972

  13. Size-biased allocation of prey from male to offspring via female: family conflicts, prey selection, and evolution of sexual size dimorphism in raptors.

    PubMed

    Sonerud, Geir A; Steen, Ronny; Løw, Line M; Røed, Line T; Skar, Kristin; Selås, Vidar; Slagsvold, Tore

    2013-05-01

    In birds with bi-parental care, the provisioning link between prey capture and delivery to dependent offspring is regarded as often symmetric between the mates. However, in raptors, the larger female usually broods and feeds the nestlings, while the smaller male provides food for the family, assisted by the female in the latter part of the nestling period, if at all. Prey items are relatively large and often impossible for nestlings to handle without extended maternal assistance. We video-recorded prey delivery and handling in nests of a raptor with a wide diet, the Eurasian kestrel Falco tinnunculus, and simultaneously observed prey transfer from male to female outside the nest. The male selectively allocated larger items, in particular birds and larger mammals, to the female for further processing and feeding of nestlings, and smaller items, in particular lizards and smaller mammals, directly to the nestlings for unassisted feeding. Hence, from the video, the female appeared to have captured larger prey than the male, while in reality no difference existed. The female's size-biased interception of the male's prey provisioning line would maximize the male's foraging time, and maximize the female's control of the allocation of food between her own need and that of the offspring. The male would maximize his control of food allocation by capturing smaller prey. This conflict would select for larger dominant females and smaller energy-efficient males, and induce stronger selection the longer the female depends on the male for self-feeding, as a proportion of the offspring dependence period. PMID:23073637

  14. Size-biased allocation of prey from male to offspring via female: family conflicts, prey selection, and evolution of sexual size dimorphism in raptors.

    PubMed

    Sonerud, Geir A; Steen, Ronny; Løw, Line M; Røed, Line T; Skar, Kristin; Selås, Vidar; Slagsvold, Tore

    2013-05-01

    In birds with bi-parental care, the provisioning link between prey capture and delivery to dependent offspring is regarded as often symmetric between the mates. However, in raptors, the larger female usually broods and feeds the nestlings, while the smaller male provides food for the family, assisted by the female in the latter part of the nestling period, if at all. Prey items are relatively large and often impossible for nestlings to handle without extended maternal assistance. We video-recorded prey delivery and handling in nests of a raptor with a wide diet, the Eurasian kestrel Falco tinnunculus, and simultaneously observed prey transfer from male to female outside the nest. The male selectively allocated larger items, in particular birds and larger mammals, to the female for further processing and feeding of nestlings, and smaller items, in particular lizards and smaller mammals, directly to the nestlings for unassisted feeding. Hence, from the video, the female appeared to have captured larger prey than the male, while in reality no difference existed. The female's size-biased interception of the male's prey provisioning line would maximize the male's foraging time, and maximize the female's control of the allocation of food between her own need and that of the offspring. The male would maximize his control of food allocation by capturing smaller prey. This conflict would select for larger dominant females and smaller energy-efficient males, and induce stronger selection the longer the female depends on the male for self-feeding, as a proportion of the offspring dependence period.

  15. Science faculty’s subtle gender biases favor male students

    PubMed Central

    Moss-Racusin, Corinne A.; Dovidio, John F.; Brescoll, Victoria L.; Graham, Mark J.; Handelsman, Jo

    2012-01-01

    Despite efforts to recruit and retain more women, a stark gender disparity persists within academic science. Abundant research has demonstrated gender bias in many demographic groups, but has yet to experimentally investigate whether science faculty exhibit a bias against female students that could contribute to the gender disparity in academic science. In a randomized double-blind study (n = 127), science faculty from research-intensive universities rated the application materials of a student—who was randomly assigned either a male or female name—for a laboratory manager position. Faculty participants rated the male applicant as significantly more competent and hireable than the (identical) female applicant. These participants also selected a higher starting salary and offered more career mentoring to the male applicant. The gender of the faculty participants did not affect responses, such that female and male faculty were equally likely to exhibit bias against the female student. Mediation analyses indicated that the female student was less likely to be hired because she was viewed as less competent. We also assessed faculty participants’ preexisting subtle bias against women using a standard instrument and found that preexisting subtle bias against women played a moderating role, such that subtle bias against women was associated with less support for the female student, but was unrelated to reactions to the male student. These results suggest that interventions addressing faculty gender bias might advance the goal of increasing the participation of women in science. PMID:22988126

  16. Inaugural address

    NASA Astrophysics Data System (ADS)

    Joshi, P. S.

    2014-03-01

    From jets to cosmos to cosmic censorship P S Joshi Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400005, India E-mail: psj@tifr.res.in 1. Introduction At the outset, I should like to acknowledge that part of the title above, which tries to capture the main flavour of this meeting, and has been borrowed from one of the plenary talks at the conference. When we set out to make the programme for the conference, we thought of beginning with observations on the Universe, but then we certainly wanted to go further and address deeper questions, which were at the very foundations of our inquiry, and understanding on the nature and structure of the Universe. I believe, we succeeded to a good extent, and it is all here for you in the form of these Conference Proceedings, which have been aptly titled as 'Vishwa Mimansa', which could be possibly translated as 'Analysis of the Universe'! It is my great pleasure and privilege to welcome you all to the ICGC-2011 meeting at Goa. The International Conference on Gravitation and Cosmology (ICGC) series of meetings are being organized by the Indian Association for General Relativity and Gravitation (IAGRG), and the first such meeting was planned and conducted in Goa in 1987, with subsequent meetings taking place at a duration of about four years at various locations in India. So, it was thought appropriate to return to Goa to celebrate the 25 years of the ICGC meetings. The recollections from that first meeting have been recorded elsewhere here in these Proceedings. The research and teaching on gravitation and cosmology was initiated quite early in India, by V V Narlikar at the Banares Hindu University, and by N R Sen in Kolkata in the 1930s. In course of time, this activity grew and gained momentum, and in early 1969, at the felicitation held for the 60 years of V V Narlikar at a conference in Ahmedabad, P C Vaidya proposed the formation of the IAGRG society, with V V Narlikar being the first President. This

  17. Evolutionary Consequences of Male Driven Sexual Selection and Sex-Biased Fitness Modifications in Drosophila melanogaster and Members of the simulans Clade

    PubMed Central

    Jagadeeshan, Santosh; Haerty, Wilfried; Moglinicka, Monika; Ahuja, Abha; De Vito, Scot; Singh, Rama S.

    2015-01-01

    Males have evolved a variety of behavioral, morphological, and physiological traits to manipulate their mates in order to maximize their chances of success. These traits are bound to influence how females respond to male behaviors and influence the nature of sexual selection/conflict. A common consequence of aggressive male mating strategies in Drosophila melanogaster is the reduction of female lifespan. Our study shows that this is common across members of the simulans clade. Reduced life expectancy of females implies that female contribution to a population is less than that of males per generation. Fitness differences between the sexes in every generation will invariably affect overall population fitness. How natural selection responds to the female deaths and thereby the unequal fitness of the sexes has rarely been addressed. We shed light on this issue and provide evidence, which suggests that additional gains of fitness by males due to their longevity and continued mating may provide one explanation as to why the loss of female fitness may be “invisible” (effectively neutral) to natural selection. Male driven sexual selection and additional, transgenerational gains of male fitness can be an important force of evolutionary change and need to be tested with other organisms. PMID:26421208

  18. Opening Address

    NASA Astrophysics Data System (ADS)

    Yamada, T.

    2014-12-01

    Ladies and Gentlemen, it is my great honor and pleasure to present an opening address of the 3rd International Workshop on "State of the Art in Nuclear Cluster Physics"(SOTANCP3). On the behalf of the organizing committee, I certainly welcome all your visits to KGU Kannai Media Center belonging to Kanto Gakuin University, and stay in Yokohama. In particular, to whom come from abroad more than 17 countries, I would appreciate your participations after long long trips from your homeland to Yokohama. The first international workshop on "State of the Art in Nuclear Cluster Physics", called SOTANCP, was held in Strasbourg, France, in 2008, and the second one was held in Brussels, Belgium, in 2010. Then the third workshop is now held in Yokohama. In this period, we had the traditional 10th cluster conference in Debrecen, Hungary, in 2012. Thus we have the traditional cluster conference and SOTANCP, one after another, every two years. This obviously shows our field of nuclear cluster physics is very active and flourishing. It is for the first time in about 10 years to hold the international workshop on nuclear cluster physics in Japan, because the last cluster conference held in Japan was in Nara in 2003, about 10 years ago. The president in Nara conference was Prof. K. Ikeda, and the chairpersons were Prof. H. Horiuchi and Prof. I. Tanihata. I think, quite a lot of persons in this room had participated at the Nara conference. Since then, about ten years passed. So, this workshop has profound significance for our Japanese colleagues. The subjects of this workshop are to discuss "the state of the art in nuclear cluster physics" and also discuss the prospect of this field. In a couple of years, we saw significant progresses of this field both in theory and in experiment, which have brought better and new understandings on the clustering aspects in stable and unstable nuclei. I think, the concept of clustering has been more important than ever. This is true also in the

  19. Convocation address.

    PubMed

    Ghatowar, P S

    1993-07-01

    The Union Deputy Minister of Health and Family Welfare in India addressed the 35th convocation of the International Institute for Population Sciences in Bombay in 1993. Officials in developing countries have been concerned about population growth for more than 30 years and have instituted policies to reduce population growth. In the 1960s, population growth in developing countries was around 2.5%, but today it is about 2%. Despite this decline, the world will have 1 billion more individuals by the year 2001. 95% of these new people will be born in developing countries. India's population size is so great that India does not have the time to wait for development to reduce population growth. Population needs to be viewed as an integrated part of overall development, since it is linked to poverty, illiteracy, environmental damage, gender issues, and reproductive health. Despite a large population size, India has made some important advancements in health and family planning. For example, India has reduced population growth (to 2.14% annually between 1981-1991), infant mortality, and its birth rate. It has increased the contraceptive use rate and life expectancy. Its southern states have been more successful at achieving demographic goals than have the northern states. India needs to implement efforts to improve living conditions, to change attitudes and perceptions about small families and contraception, and to promote family planning acceptance earlier among young couples. Improvement of living conditions is especially important in India, since almost 33% of the people live in poverty. India needs to invest in nutrition, health, and education. The mass media and nongovernmental organizations need to create population awareness and demand for family planning services. Improvement in women's status accelerates fertility decline, as has happened in Kerala State. The government needs to facilitate generation of jobs. Community participation is needed for India to achieve

  20. Welcome Address

    NASA Astrophysics Data System (ADS)

    Kiku, H.

    2014-12-01

    Ladies and Gentlemen, It is an honor for me to present my welcome address in the 3rd International Workshop on "State of the Art in Nuclear Cluster Physics"(SOTANCP3), as the president of Kanto Gakuin University. Particularly to those from abroad more than 17 countries, I am very grateful for your participation after long long trips from your home to Yokohama. On the behalf of the Kanto Gakuin University, we certainly welcome your visit to our university and stay in Yokohama. First I would like to introduce Kanto Gakuin University briefly. Kanto Gakuin University, which is called KGU, traces its roots back to the Yokohama Baptist Seminary founded in 1884 in Yamate, Yokohama. The seminary's founder was Albert Arnold Bennett, alumnus of Brown University, who came to Japan from the United States to establish a theological seminary for cultivating and training Japanese missionaries. Now KGU is a major member of the Kanto Gakuin School Corporation, which is composed of two kindergartens, two primary schools, two junior high schools, two senior high schools as well as KGU. In this university, we have eight faculties with graduate school including Humanities, Economics, Law, Sciences and Engineering, Architecture and Environmental Design, Human and Environmental Studies, Nursing, and Law School. Over eleven thousands students are currently learning in our university. By the way, my major is the geotechnical engineering, and I belong to the faculty of Sciences and Engineering in my university. Prof. T. Yamada, here, is my colleague in the same faculty. I know that the nuclear physics is one of the most active academic fields in the world. In fact, about half of the participants, namely, more than 50 scientists, come from abroad in this conference. Moreover, I know that the nuclear physics is related to not only the other fundamental physics such as the elementary particle physics and astrophysics but also chemistry, medical sciences, medical cares, and radiation metrology

  1. Expert witness blinding strategies to mitigate bias in radiology malpractice cases: a comprehensive review of the literature.

    PubMed

    Durand, Daniel J; Robertson, Christopher T; Agarwal, Gautam; Duszak, Richard; Krupinski, Elizabeth A; Itri, Jason N; Fotenos, Anthony; Savoie, Brent; Ding, Alexander; Lewin, Jonathan S

    2014-09-01

    Like all physicians, radiologists in the United States are subject to frequent and costly medical malpractice claims. Legal scholars and physicians concur that the US civil justice system is neither precise nor accurate in determining whether malpractice has truly occurred in cases in which claims are made. Sometimes, this inaccuracy is driven by biases inherent in medical expert-witness opinions. For example, expert-witness testimony involving "missed" radiology findings can be negatively affected by several cognitive biases, such as contextual bias, hindsight bias, and outcome bias. Biases inherent in the US legal system, such as selection bias, compensation bias, and affiliation bias, also play important roles. Fortunately, many of these biases can be significantly mitigated or eliminated through the use of appropriate blinding techniques. This paper reviews the major works on expert-witness blinding in the legal scholarship and the radiology professional literature. Its purpose is to acquaint the reader with the evidence that unblinded expert-witness testimony is tainted by multiple sources of bias and to examine proposed strategies for addressing these biases through blinding. PMID:25041992

  2. Evaluation of an Alcohol Abuse Prevention Program Correcting for Self Selection.

    ERIC Educational Resources Information Center

    Greenfield, Thomas K.; Duncan, Gregory M.

    Self-selection bias poses a major threat to the validity of research findings in naturalistic, quasi-experimental, or single-group designs. A new method of addressing self-selection bias in naturalistic evaluations of prevention programs was implemented. The study, involving voluntary exposure to multicomponent interventions, was developed and…

  3. Selected Speeches, Addresses, Remarks, and Testimony of the Assistant Secretary of Education for Educational Research and Improvement, October 23-December 11, 1989.

    ERIC Educational Resources Information Center

    Cross, Christopher T.

    This document consists of 10 separate speeches, addresses, remarks, or testimony made by the Assistant Secretary of Education for Educational Research and Improvement during the period from October 23 to December 11, 1989. The addresses are arranged chronologically as follows: (1) Testimony, Senate Subcommittee on Governmental Information and…

  4. Bias-selectable dual-band mid-/long-wavelength infrared photodetectors based on InAs/InAs{sub 1−x}Sb{sub x} type-II superlattices

    SciTech Connect

    Haddadi, A.; Chevallier, R.; Chen, G.; Hoang, A. M.; Razeghi, M.

    2015-01-05

    A high performance bias-selectable mid-/long-wavelength infrared photodetector based on InAs/InAs{sub 1−x}Sb{sub x} type-II superlattices on GaSb substrate has been demonstrated. The mid- and long-wavelength channels' 50% cut-off wavelengths were ∼5.1 and ∼9.5 μm at 77 K. The mid-wavelength channel exhibited a quantum efficiency of 45% at 100 mV bias voltage under front-side illumination and without any anti-reflection coating. With a dark current density of 1 × 10{sup −7} A/cm{sup 2} under 100 mV applied bias, the mid-wavelength channel exhibited a specific detectivity of 8.2 × 10{sup 12 }cm·√(Hz)/W at 77 K. The long-wavelength channel exhibited a quantum efficiency of 40%, a dark current density of 5.7 × 10{sup −4} A/cm{sup 2} under −150 mV applied bias at 77 K, providing a specific detectivity value of 1.64 × 10{sup 11 }cm·√(Hz)/W.

  5. The Utility of Impulsive Bias and Altered Decision Making as Predictors of Drug Efficacy and Target Selection: Rethinking Behavioral Screening for Antidepressant Drugs.

    PubMed

    Marek, Gerard J; Day, Mark; Hudzik, Thomas J

    2016-03-01

    Cognitive dysfunction may be a core feature of major depressive disorder, including affective processing bias, abnormal response to negative feedback, changes in decision making, and increased impulsivity. Accordingly, a translational medicine paradigm predicts clinical action of novel antidepressants by examining drug-induced changes in affective processing bias. With some exceptions, these concepts have not been systematically applied to preclinical models to test new chemical entities. The purpose of this review is to examine whether an empirically derived behavioral screen for antidepressant drugs may screen for compounds, at least in part, by modulating an impulsive biasing of responding and altered decision making. The differential-reinforcement-of-low-rate (DRL) 72-second schedule is an operant schedule with a documented fidelity for discriminating antidepressant drugs from nonantidepressant drugs. However, a theoretical basis for this empirical relationship has been lacking. Therefore, this review will discuss whether response bias toward impulsive behavior may be a critical screening characteristic of DRL behavior requiring long inter-response times to obtain rewards. This review will compare and contrast DRL behavior with the five-choice serial reaction time task, a test specifically designed for assessing motoric impulsivity, with respect to psychopharmacological testing and the neural basis of distributed macrocircuits underlying these tasks. This comparison suggests that the existing empirical basis for the DRL 72-second schedule as a pharmacological screen for antidepressant drugs is complemented by a novel hypothesis that altering impulsive response bias for rodents trained on this operant schedule is a previously unrecognized theoretical cornerstone for this screening paradigm. PMID:26699144

  6. Analysis of an influence of the bias correction method on the projected changes of flood indices in the selected catchments in Poland

    NASA Astrophysics Data System (ADS)

    Osuch, Marzena; Lawrence, Deborah; Meresa, Hadush K.; Napiórkowski, Jaroslaw J.; Romanowicz, Renata J.

    2016-04-01

    The aim of the study is an estimation of the uncertainty in flood indices introduced by bias correction of climate model variables in ten catchments in Poland. A simulation approach is used to obtain daily flows in catchments under changing climatic conditions, following the RCP4.5 and RCP8.5 emission scenarios. Climate projections were obtained from the EURO-CORDEX initiative, and time series of precipitation and air temperature from different RCM/GCMs for the periods: 1971-2000, 2021-2050 and 2071-2100 were used. The climate model outputs in the Poland area are highly biased; therefore, additional post processing in the form of bias correction of precipitation and temperature is needed. In this work we used four versions of the quantile mapping method (empirical quantile mapping, and three distribution based mappings: double gamma, single gamma and Birnbaum-Sanders) for correction of the precipitation time series and one method for air temperature correction (empirical quantile method). The HBV rainfall-runoff catchment-based model is used to estimate future flow time series. The models are calibrated using the available precipitation, air temperature, and flow observations for the period 1971-2000. Model performance is evaluated using observed data for the period 2001-2010. We also verify performance using the EURO-CORDEX simulations for the reference period (1971-2000), both with and without bias correction of the RCM/GCM outputs. Finally, the models are run for the future climate simulated by the RCM/GCM models for the years: 2021-2050 and 2071-2100. Changes in the mean annual flood and in flood quantiles are analysed and the effect of bias correction on the estimated changes is also considered. The results indicate substantial differences between climate models and catchments. The regional variability has a close relationship with the flood regime type. Catchments where high flows are expected to increase have a rainfall-dominated flood regime in the current

  7. Instilling New Habits: Addressing Implicit Bias in Healthcare Professionals

    ERIC Educational Resources Information Center

    Byrne, Aidan; Tanesini, Alessandra

    2015-01-01

    There appears to be a fundamental inconsistency between research which shows that some minority groups consistently receive lower quality healthcare and the literature indicating that healthcare workers appear to hold equality as a core personal value. Recent evidence using Implicit Association Tests suggests that these disparities in outcome may…

  8. Single-Sex Schools, Student Achievement, and Course Selection: Evidence from Rule-Based Student Assignments in Trinidad and Tobago. NBER Working Paper No. 16817

    ERIC Educational Resources Information Center

    Jackson, C. Kirabo

    2011-01-01

    Existing studies on single-sex schooling suffer from biases due to student selection to schools and single-sex schools being better in unmeasured ways. In Trinidad and Tobago students are assigned to secondary schools based on an algorithm allowing one to address self-selection bias and cleanly estimate an upper-bound single-sex school effect. The…

  9. Random property allocation: A novel geographic imputation procedure based on a complete geocoded address file.

    PubMed

    Walter, Scott R; Rose, Nectarios

    2013-09-01

    Allocating an incomplete address to randomly selected property coordinates within a locality, known as random property allocation, has many advantages over other geoimputation techniques. We compared the performance of random property allocation to four other methods under various conditions using a simulation approach. All methods performed well for large spatial units, but random property allocation was the least prone to bias and error under volatile scenarios with small units and low prevalence. Both its coordinate based approach as well as the random process of assignment contribute to its increased accuracy and reduced bias in many scenarios. Hence it is preferable to fixed or areal geoimputation for many epidemiological and surveillance applications.

  10. Multiple-Replica Strategies for Free-Energy Calculations in NAMD: Multiple-Walker Adaptive Biasing Force and Walker Selection Rules.

    PubMed

    Comer, Jeffrey; Phillips, James C; Schulten, Klaus; Chipot, Christophe

    2014-12-01

    From the most powerful supercomputers to multicore desktops and laptops, parallel computing architectures have been in the mainstream for some time. However, numerical schemes for calculating free energies in molecular systems that directly leverage this hardware paradigm, usually taking the form of multiple-replica strategies, are just now on the cusp of becoming standard practice. Here, we present a modification of the popular molecular dynamics program NAMD that is envisioned to facilitate the use of powerful multiple-replica strategies to improve ergodic sampling for a specific class of free-energy methods known as adaptive biasing force. We describe the software implementation in a so-called multiple-walker context, alongside the interface that makes the proposed approach accessible to the end users. We further evaluate the performance of the adaptive biasing force multiple-walker strategy for a model system, namely, the reversible folding of a short peptide, and show, in particular, in regions of the transition coordinate where convergence of the free-energy calculation is encumbered by hidden barriers, that the multiple-walker strategy can yield far more reliable results in appreciably less real time on parallel architectures, relative to standard, single-replica calculations. PMID:26583211

  11. Multiple-Replica Strategies for Free-Energy Calculations in NAMD: Multiple-Walker Adaptive Biasing Force and Walker Selection Rules.

    PubMed

    Comer, Jeffrey; Phillips, James C; Schulten, Klaus; Chipot, Christophe

    2014-12-01

    From the most powerful supercomputers to multicore desktops and laptops, parallel computing architectures have been in the mainstream for some time. However, numerical schemes for calculating free energies in molecular systems that directly leverage this hardware paradigm, usually taking the form of multiple-replica strategies, are just now on the cusp of becoming standard practice. Here, we present a modification of the popular molecular dynamics program NAMD that is envisioned to facilitate the use of powerful multiple-replica strategies to improve ergodic sampling for a specific class of free-energy methods known as adaptive biasing force. We describe the software implementation in a so-called multiple-walker context, alongside the interface that makes the proposed approach accessible to the end users. We further evaluate the performance of the adaptive biasing force multiple-walker strategy for a model system, namely, the reversible folding of a short peptide, and show, in particular, in regions of the transition coordinate where convergence of the free-energy calculation is encumbered by hidden barriers, that the multiple-walker strategy can yield far more reliable results in appreciably less real time on parallel architectures, relative to standard, single-replica calculations.

  12. Precision and bias of selected analytes reported by the National Atmospheric Deposition Program and National Trends Network, 1983; and January 1980 through September 1984

    USGS Publications Warehouse

    Schroder, L.J.; Bricker, A.W.; Willoughby, T.C.

    1985-01-01

    Blind-audit samples with known analyte concentrations have been prepared by the U.S. Geological Survey and distributed to the National Atmospheric Deposition Program 's Central Analytical Laboratory. The difference between the National Atmospheric Deposition Program and National Trends Network reported analyte concentrations and known analyte concentrations have been calculated, and the bias has been determined. Calcium, magnesium , sodium, and chloride were biased at the 99-percent confidence limit; potassium and sulfate were unbiased at the 99-percent confidence limit, for 1983 results. Relative-percent differences between the measured and known analyte concentration for calcium , magnesium, sodium, potassium, chloride, and sulfate have been calculated for 1983. The median relative percent difference for calcium was 17.0; magnesium was 6.4; sodium was 10.8; potassium was 6.4; chloride was 17.2; and sulfate was -5.3. These relative percent differences should be used to correct the 1983 data before user-analysis of the data. Variances have been calculated for calcium, magnesium, sodium, potassium, chloride, and sulfate determinations. These variances should be applicable to natural-sample analyte concentrations reported by the National Atmospheric Deposition Program and National Trends Network for calendar year 1983. (USGS)

  13. Biased signaling at chemokine receptors.

    PubMed

    Corbisier, Jenny; Galès, Céline; Huszagh, Alexandre; Parmentier, Marc; Springael, Jean-Yves

    2015-04-10

    The ability of G protein-coupled receptors (GPCRs) to activate selective signaling pathways according to the conformation stabilized by bound ligands (signaling bias) is a challenging concept in the GPCR field. Signaling bias has been documented for several GPCRs, including chemokine receptors. However, most of these studies examined the global signaling bias between G protein- and arrestin-dependent pathways, leaving unaddressed the potential bias between particular G protein subtypes. Here, we investigated the coupling selectivity of chemokine receptors CCR2, CCR5, and CCR7 in response to various ligands with G protein subtypes by using bioluminescence resonance energy transfer biosensors monitoring directly the activation of G proteins. We also compared data obtained with the G protein biosensors with those obtained with other functional readouts, such as β-arrestin-2 recruitment, cAMP accumulation, and calcium mobilization assays. We showed that the binding of chemokines to CCR2, CCR5, and CCR7 activated the three Gαi subtypes (Gαi1, Gαi2, and Gαi3) and the two Gαo isoforms (Gαoa and Gαob) with potencies that generally correlate to their binding affinities. In addition, we showed that the binding of chemokines to CCR5 and CCR2 also activated Gα12, but not Gα13. For each receptor, we showed that the relative potency of various agonist chemokines was not identical in all assays, supporting the notion that signaling bias exists at chemokine receptors.

  14. On the relative independence of thinking biases and cognitive ability.

    PubMed

    Stanovich, Keith E; West, Richard F

    2008-04-01

    In 7 different studies, the authors observed that a large number of thinking biases are uncorrelated with cognitive ability. These thinking biases include some of the most classic and well-studied biases in the heuristics and biases literature, including the conjunction effect, framing effects, anchoring effects, outcome bias, base-rate neglect, "less is more" effects, affect biases, omission bias, myside bias, sunk-cost effect, and certainty effects that violate the axioms of expected utility theory. In a further experiment, the authors nonetheless showed that cognitive ability does correlate with the tendency to avoid some rational thinking biases, specifically the tendency to display denominator neglect, probability matching rather than maximizing, belief bias, and matching bias on the 4-card selection task. The authors present a framework for predicting when cognitive ability will and will not correlate with a rational thinking tendency.

  15. Bias in the Classroom: Types, Frequencies, and Responses

    ERIC Educational Resources Information Center

    Boysen, Guy A.; Vogel, David L.

    2009-01-01

    Incidents of bias still occur in college classrooms, but no research has specifically explored this topic. To address this gap in the literature, professors (N = 333) completed anonymous surveys assessing types of bias they perceived in their classroom, their responses to the bias, and the perceived success of their responses. Results indicated…

  16. Cultural Bias in Children's Storybooks: Implications for Education.

    ERIC Educational Resources Information Center

    Timm, Joan S.

    This study addresses concern about bias in educational materials for elementary school pupils. Children's storybooks were examined for the appearance of biases across the cultural categories of race, ethnicity, gender, age, socioeconomic level, religion, and environmental background. These biases included stereotyping, invisibility (omission of…

  17. A Comparison of the Selectivity of Extraction of [PtCl6](2-) by Mono-, Bi-, and Tripodal Receptors That Address Its Outer Coordination Sphere.

    PubMed

    Warr, Rebecca J; Bell, Katherine J; Gadzhieva, Anastasia; Cabot, Rafel; Ellis, Ross J; Chartres, Jy; Henderson, David K; Lykourina, Eleni; Wilson, A Matthew; Love, Jason B; Tasker, Peter A; Schröder, Martin

    2016-06-20

    Extraction and binding studies of [PtCl6](2-) are reported for 24 mono-, bi-, and tripodal extractants containing tris(2-aminoethyl)amine (TREN) or tris(3-aminopropyl)amine (TRPN) scaffolds. These reagents are designed to recognize the outer coordination sphere of [PtCl6](2-) and to show selectivity over chloride anion under acidic conditions. Extraction from 0.6 M HCl involves protonation of the N-center in tertiary amines containing one, two, or three urea, amide, or sulfonamide hydrogen-bond donors to set up the following equilibrium: 2L(org) + 2H(+) + [PtCl6](2-) ⇌ [(LH)2PtCl6](org). All reagents show higher Pt loading than trioctylamine, which was used as a positive control to represent commercial trialkylamine reagents. The loading of [PtCl6](2-) depends on the number of pendant amides in the extractant and follows the order tripodal > bipodal > monopodal, with urea-containing extractants outperforming amide and sulfonamide analogues. A different series of reagents in which one, two, or three of the alkyl groups in tris-2-ethylhexylamine are replaced by 3-N'-hexylpropanamide groups all show a comparably high affinity for [PtCl6](2-) and high selectivity over chloride anion in extractions from aqueous acidic solutions. (1)H NMR titration of three extractants [LH·Cl] with [(Oct4N)2PtCl6] in CDCl3 provides evidence for high selectivity for [PtCl6](2-) over chloride for tri- and bipodal extractants, which show higher binding constants than a monopodal analogue. PMID:27256829

  18. Bias structure to efficiently package a magnetic bubble domain device

    NASA Technical Reports Server (NTRS)

    Chen, Thomas T. (Inventor)

    1978-01-01

    A single, compact bias structure to efficiently package a plurality of magnetic bubble domain device chips having different bias requirements. The vertical magnetic field distribution within the bias structure air gap is selectively controlled by a magnetically soft field adjusting assembly suitably attached within the bias structure. The size and configuration of the field adjusting assembly tailors local field variations within the air gap to correspond with the bias requirements of the bubble domain chips disposed therein.

  19. Only pick the right grains: Modelling the bias due to subjective grain-size interval selection for chronometric and fingerprinting approaches.

    NASA Astrophysics Data System (ADS)

    Dietze, Michael; Fuchs, Margret; Kreutzer, Sebastian

    2016-04-01

    Many modern approaches of radiometric dating or geochemical fingerprinting rely on sampling sedimentary deposits. A key assumption of most concepts is that the extracted grain-size fraction of the sampled sediment adequately represents the actual process to be dated or the source area to be fingerprinted. However, these assumptions are not always well constrained. Rather, they have to align with arbitrary, method-determined size intervals, such as "coarse grain" or "fine grain" with partly even different definitions. Such arbitrary intervals violate principal process-based concepts of sediment transport and can thus introduce significant bias to the analysis outcome (i.e., a deviation of the measured from the true value). We present a flexible numerical framework (numOlum) for the statistical programming language R that allows quantifying the bias due to any given analysis size interval for different types of sediment deposits. This framework is applied to synthetic samples from the realms of luminescence dating and geochemical fingerprinting, i.e. a virtual reworked loess section. We show independent validation data from artificially dosed and subsequently mixed grain-size proportions and we present a statistical approach (end-member modelling analysis, EMMA) that allows accounting for the effect of measuring the compound dosimetric history or geochemical composition of a sample. EMMA separates polymodal grain-size distributions into the underlying transport process-related distributions and their contribution to each sample. These underlying distributions can then be used to adjust grain-size preparation intervals to minimise the incorporation of "undesired" grain-size fractions.

  20. Clinicians’ Implicit Ethnic/Racial Bias and Perceptions of Care Among Black and Latino Patients

    PubMed Central

    Blair, Irene V.; Steiner, John F.; Fairclough, Diane L.; Hanratty, Rebecca; Price, David W.; Hirsh, Holen K.; Wright, Leslie A.; Bronsert, Michael; Karimkhani, Elhum; Magid, David J.; Havranek, Edward P.

    2013-01-01

    PURPOSE We investigated whether clinicians’ explicit and implicit ethnic/racial bias is related to black and Latino patients’ perceptions of their care in established clinical relationships. METHODS We administered a telephone survey to 2,908 patients, stratified by ethnicity/race, and randomly selected from the patient panels of 134 clinicians who had previously completed tests of explicit and implicit ethnic/racial bias. Patients completed the Primary Care Assessment Survey, which addressed their clinicians’ interpersonal treatment, communication, trust, and contextual knowledge. We created a composite measure of patient-centered care from the 4 subscales. RESULTS Levels of explicit bias were low among clinicians and unrelated to patients’ perceptions. Levels of implicit bias varied among clinicians, and those with greater implicit bias were rated lower in patient-centered care by their black patients as compared with a reference group of white patients (P = .04). Latino patients gave the clinicians lower ratings than did other groups (P <.0001), and this did not depend on the clinicians’ implicit bias (P = .98). CONCLUSIONS This is among the first studies to investigate clinicians’ implicit bias and communication processes in ongoing clinical relationships. Our findings suggest that clinicians’ implicit bias may jeopardize their clinical relationships with black patients, which could have negative effects on other care processes. As such, this finding supports the Institute of Medicine’s suggestion that clinician bias may contribute to health disparities. Latinos’ overall greater concerns about their clinicians appear to be based on aspects of care other than clinician bias. PMID:23319505

  1. Divertor bias experiments

    NASA Astrophysics Data System (ADS)

    Staebler, G. M.

    1994-06-01

    Electrical biasing of the divertor target plates has recently been implemented on several tokamaks. The results of these experiments to date will be reviewed in this paper. The bias electrode configuration is unique in each experiment. The effects of biasing on the scrape-off layer (SOL) plasma also differ. By comparing results between machines, and using theoretical models, an understanding of the basic physics of biasing begins to emerge. Divertor biasing has been demonstrated to have a strong influence on the particle and energy transport within the SOL. The ability to externally control the SOL plasma with biasing has promising applications to future tokamak reactors.

  2. Irrelevant tactile stimulation biases visual exploration in external coordinates

    PubMed Central

    Ossandón, José P.; König, Peter; Heed, Tobias

    2015-01-01

    We evaluated the effect of irrelevant tactile stimulation on humans’ free-viewing behavior during the exploration of complex static scenes. Specifically, we address the questions of (1) whether task-irrelevant tactile stimulation presented to subjects’ hands can guide visual selection during free viewing; (2) whether tactile stimulation can modulate visual exploratory biases that are independent of image content and task goals; and (3) in which reference frame these effects occur. Tactile stimulation to uncrossed and crossed hands during the viewing of static images resulted in long-lasting modulation of visual orienting responses. Subjects showed a well-known leftward bias during the early exploration of images, and this bias was modulated by tactile stimulation presented at image onset. Tactile stimulation, both at image onset and later during the trials, biased visual orienting toward the space ipsilateral to the stimulated hand, both in uncrossed and crossed hand postures. The long-lasting temporal and global spatial profile of the modulation of free viewing exploration by touch indicates that cross-modal cues produce orienting responses, which are coded exclusively in an external reference frame. PMID:26021612

  3. Irrelevant tactile stimulation biases visual exploration in external coordinates.

    PubMed

    Ossandón, José P; König, Peter; Heed, Tobias

    2015-05-29

    We evaluated the effect of irrelevant tactile stimulation on humans' free-viewing behavior during the exploration of complex static scenes. Specifically, we address the questions of (1) whether task-irrelevant tactile stimulation presented to subjects' hands can guide visual selection during free viewing; (2) whether tactile stimulation can modulate visual exploratory biases that are independent of image content and task goals; and (3) in which reference frame these effects occur. Tactile stimulation to uncrossed and crossed hands during the viewing of static images resulted in long-lasting modulation of visual orienting responses. Subjects showed a well-known leftward bias during the early exploration of images, and this bias was modulated by tactile stimulation presented at image onset. Tactile stimulation, both at image onset and later during the trials, biased visual orienting toward the space ipsilateral to the stimulated hand, both in uncrossed and crossed hand postures. The long-lasting temporal and global spatial profile of the modulation of free viewing exploration by touch indicates that cross-modal cues produce orienting responses, which are coded exclusively in an external reference frame.

  4. Political Bias in the College Classroom: A Literature Review

    ERIC Educational Resources Information Center

    Linvill, Darren L.; Havice, Pamela A.

    2011-01-01

    This review of literature explores current research addressing political bias in higher education. The perception of a pervasive liberal political bias in academia is addressed first. This discussion focuses on the debate surrounding the Academic Bill of Rights, a document that outlines principles defending students' academic freedom and advocates…

  5. Demonstrating the Correspondence Bias

    ERIC Educational Resources Information Center

    Howell, Jennifer L.; Shepperd, James A.

    2011-01-01

    Among the best-known and most robust biases in person perception is the correspondence bias--the tendency for people to make dispositional, rather than situational, attributions for an actor's behavior. The correspondence bias appears in virtually every social psychology textbook and in many introductory psychology textbooks, yet the authors'…

  6. Bias in Grading

    ERIC Educational Resources Information Center

    Malouff, John

    2008-01-01

    Bias in grading can be conscious or unconscious. The author describes different types of bias, such as those based on student attractiveness or performance in prior courses, and a variety of methods of reducing bias, including keeping students anonymous during grading and using detailed criteria for subjective grading.

  7. High performance bias-selectable three-color Short-wave/Mid-wave/Long-wave Infrared Photodetectors based on Type-II InAs/GaSb/AlSb superlattices

    PubMed Central

    Hoang, Anh Minh; Dehzangi, Arash; Adhikary, Sourav; Razeghi, Manijeh

    2016-01-01

    We propose a new approach in device architecture to realize bias-selectable three-color shortwave-midwave-longwave infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices. The effect of conduction band off-set and different doping levels between two absorption layers are employed to control the turn-on voltage for individual channels. The optimization of these parameters leads to a successful separation of operation regimes; we demonstrate experimentally three-color photodiodes without using additional terminal contacts. As the applied bias voltage varies, the photodiodes exhibit sequentially the behavior of three different colors, corresponding to the bandgap of three absorbers. Well defined cut-offs and high quantum efficiency in each channel are achieved. Such all-in-one devices also provide the versatility of working as single or dual-band photodetectors at high operating temperature. With this design, by retaining the simplicity in device fabrication, this demonstration opens the prospect for three-color infrared imaging. PMID:27051979

  8. High performance bias-selectable three-color Short-wave/Mid-wave/Long-wave Infrared Photodetectors based on Type-II InAs/GaSb/AlSb superlattices

    NASA Astrophysics Data System (ADS)

    Hoang, Anh Minh; Dehzangi, Arash; Adhikary, Sourav; Razeghi, Manijeh

    2016-04-01

    We propose a new approach in device architecture to realize bias-selectable three-color shortwave-midwave-longwave infrared photodetectors based on InAs/GaSb/AlSb type-II superlattices. The effect of conduction band off-set and different doping levels between two absorption layers are employed to control the turn-on voltage for individual channels. The optimization of these parameters leads to a successful separation of operation regimes; we demonstrate experimentally three-color photodiodes without using additional terminal contacts. As the applied bias voltage varies, the photodiodes exhibit sequentially the behavior of three different colors, corresponding to the bandgap of three absorbers. Well defined cut-offs and high quantum efficiency in each channel are achieved. Such all-in-one devices also provide the versatility of working as single or dual-band photodetectors at high operating temperature. With this design, by retaining the simplicity in device fabrication, this demonstration opens the prospect for three-color infrared imaging.

  9. Use of a Synthetic Biosensor for Neutralizing Activity-Biased Selection of Monoclonal Antibodies against Atroxlysin-I, an Hemorrhagic Metalloproteinase from Bothrops atrox Snake Venom

    PubMed Central

    Schneider, Francisco Santos; Nguyen, Dung Le; Castro, Karen Larissa; Cobo, Sandra; Machado de Avila, Ricardo Andrez; Ferreira, Nivia de Assis; Sanchez, Eladio Flores; Nguyen, Christophe; Granier, Claude; Galéa, Pascale; Chávez-Olortegui, Carlos; Molina, Franck

    2014-01-01

    Background The snake Bothrops atrox is responsible for the majority of envenomings in the northern region of South America. Severe local effects, including hemorrhage, which are mainly caused by snake venom metalloproteinases (SVMPs), are not fully neutralized by conventional serum therapy. Little is known about the immunochemistry of the P-I SVMPs since few monoclonal antibodies (mAbs) against these molecules have been obtained. In addition, producing toxin-neutralizing mAbs remains very challenging. Methodology/Principal Findings Here, we report on the set-up of a functional screening based on a synthetic peptide used as a biosensor to select neutralizing mAbs against SVMPs and the successful production of neutralizing mAbs against Atroxlysin-I (Atr-I), a P-I SVMP from B. atrox. Hybridomas producing supernatants with inhibitory effect against the proteolytic activity of Atr-I towards the FRET peptide Abz-LVEALYQ-EDDnp were selected. Six IgG1 Mabs were obtained (named mAbatr1 to mAbatr6) and also two IgM. mAbatrs1, 2, 3 and 6 were purified. All showed a high specific reactivity, recognizing only Atr-I and B. atrox venom in ELISA and a high affinity, showing equilibrium constants in the nM range for Atr-I. These mAbatrs were not able to bind to Atr-I overlapping peptides, suggesting that they recognize conformational epitopes. Conclusions/Significance For the first time a functional screening based on a synthetic biosensor was successfully used for the selection of neutralizing mAbs against SVMPs. PMID:24762927

  10. Attentional bias in math anxiety.

    PubMed

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms.

  11. Attentional bias in math anxiety.

    PubMed

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms. PMID:26528208

  12. Attentional bias in math anxiety

    PubMed Central

    Rubinsten, Orly; Eidlin, Hili; Wohl, Hadas; Akibli, Orly

    2015-01-01

    Cognitive theory from the field of general anxiety suggests that the tendency to display attentional bias toward negative information results in anxiety. Accordingly, the current study aims to investigate whether attentional bias is involved in math anxiety (MA) as well (i.e., a persistent negative reaction to math). Twenty seven participants (14 with high levels of MA and 13 with low levels of MA) were presented with a novel computerized numerical version of the well established dot probe task. One of six types of prime stimuli, either math related or typically neutral, was presented on one side of a computer screen. The prime was preceded by a probe (either one or two asterisks) that appeared in either the prime or the opposite location. Participants had to discriminate probe identity (one or two asterisks). Math anxious individuals reacted faster when the probe was at the location of the numerical related stimuli. This suggests the existence of attentional bias in MA. That is, for math anxious individuals, the cognitive system selectively favored the processing of emotionally negative information (i.e., math related words). These findings suggest that attentional bias is linked to unduly intense MA symptoms. PMID:26528208

  13. Judgmental biases in decision support for strike operations

    NASA Astrophysics Data System (ADS)

    Kulick, Jonathan D.; Davis, Paul K.

    2003-09-01

    Human decisionmaking does not typically fit the classical analytic model, and the heuristics employed may yield a variety of biased judgments. These biases are often considered inherently adverse, but may be functional in some cases. Decision support systems can mitigate some biases, but often introduce others. "Debiasing" decision support systems entails designing DSS to address expected biases, and to preclude inducing new ones. High-level C2 decisionmaking processes are poorly understood, but these general principles and lessons learned in other fields are expected to obtain. A notional air campaign illustrates potential biases in a commander"s judgment during planning and execution, and the role of debiasing operational DSS.

  14. Interpretation biases in paranoia.

    PubMed

    Savulich, George; Freeman, Daniel; Shergill, Sukhi; Yiend, Jenny

    2015-01-01

    Information in the environment is frequently ambiguous in meaning. Emotional ambiguity, such as the stare of a stranger, or the scream of a child, encompasses possible good or bad emotional consequences. Those with elevated vulnerability to affective disorders tend to interpret such material more negatively than those without, a phenomenon known as "negative interpretation bias." In this study we examined the relationship between vulnerability to psychosis, measured by trait paranoia, and interpretation bias. One set of material permitted broadly positive/negative (valenced) interpretations, while another allowed more or less paranoid interpretations, allowing us to also investigate the content specificity of interpretation biases associated with paranoia. Regression analyses (n=70) revealed that trait paranoia, trait anxiety, and cognitive inflexibility predicted paranoid interpretation bias, whereas trait anxiety and cognitive inflexibility predicted negative interpretation bias. In a group comparison those with high levels of trait paranoia were negatively biased in their interpretations of ambiguous information relative to those with low trait paranoia, and this effect was most pronounced for material directly related to paranoid concerns. Together these data suggest that a negative interpretation bias occurs in those with elevated vulnerability to paranoia, and that this bias may be strongest for material matching paranoid beliefs. We conclude that content-specific biases may be important in the cause and maintenance of paranoid symptoms.

  15. Political bias is tenacious.

    PubMed

    Ditto, Peter H; Wojcik, Sean P; Chen, Eric Evan; Grady, Rebecca Hofstein; Ringel, Megan M

    2015-01-01

    Duarte et al. are right to worry about political bias in social psychology but they underestimate the ease of correcting it. Both liberals and conservatives show partisan bias that often worsens with cognitive sophistication. More non-liberals in social psychology is unlikely to speed our convergence upon the truth, although it may broaden the questions we ask and the data we collect.

  16. Investigating Test Bias.

    ERIC Educational Resources Information Center

    Hoepfner, Ralph; Strickland, Guy P.

    This study investigates the question of test bias to develop an index of the appropriateness of a test to a particular socioeconomic or racial-ethnic group. Bias is defined as an item by race interaction in an analysis-of-variance design. The sample of 172 third graders at two integrated schools in a large California school district, included 26…

  17. Sampler bias -- Phase 1

    SciTech Connect

    Blanchard, R.J.

    1995-03-07

    This documents Phase 1 determinations on sampler induced bias for four sampler types used in tank characterization. Each sampler, grab sampler or bottle-on-a-string, auger sampler, sludge sampler and universal sampler, is briefly discussed and their physical limits noted. Phase 2 of this document will define additional testing and analysis to further define Sampler Bias.

  18. Methodological approaches to population based research of screening procedures in the presence of selection bias and exposure measurement error: colonoscopy and colorectal cancer outcomes in Ontario

    PubMed Central

    2013-01-01

    .60% using instrumental variable analysis. For CRC mortality, the ARR was 0.08% in the unadjusted model, multivariate logistic regression model and for a propensity score- weighted outcome model, 0.10% using propensity score matched model and 0.17% using the IVA model. Conclusions Colonoscopy use reduced the risk of CRC incidence and mortality in the restricted cohort. The study highlights the importance of appropriate selection of study subjects and use of analytic methods for the evaluation of screening methods using observational data. PMID:23617792

  19. The thinker: opposing directionality of lighting bias within sculptural artwork

    PubMed Central

    Sedgewick, Jennifer R.; Weiers, Bradley; Stewart, Aaron; Elias, Lorin J.

    2015-01-01

    Individuals tend to perceive the direction of light to come from above and slightly from the left; it has been speculated that this phenomenon is also producing similar lighting preferences within 2-dimensional artworks (e.g., paintings, advertisements). The purpose of the present study was to address if lighting bias was present in the 3-dimensional medium of sculpture by implementing a virtual art gallery lighting paradigm. Thirty-nine participants completed a computer task that consisted of 48 galleries each containing one sculpture (24 original sculptures, 24 mirror-reversed) which was surrounded by eight lights (above/below, left/right, front/back). Participants would select one light source to illuminate the sculpture in a manner they perceived to be the most aesthetically pleasing. The results indicated a significant preference for lights positioned from above and from the right, a finding that is contradictory to previous lighting bias research examining artworks. An interpretation for the rightward bias applies the perceptual concept of subjective lighting equality. Objects illuminated from the left typically appear brighter in comparison to right-side lighting; in sculpture, however, increased luminosity can reduce the sculptural detail, and may have been compensated via right-side lighting choices within the lighting task. PMID:25999840

  20. Sex-biased movement in the guppy (Poecilia reticulata).

    PubMed

    Croft, Darren P; Albanese, Brett; Arrowsmith, Bethany J; Botham, Marc; Webster, Michael; Krause, Jens

    2003-09-01

    The movement strategies of birds and mammals are often closely linked to their mating system, but few studies have examined the relationship between mating systems and movement in fishes. We examined the movement patterns of the guppy ( Poecilia reticulata) in the Arima river of Trinidad and predicted that sexual asymmetry in reproductive investment would result in male-biased movement. Since male guppies maximize their reproductive success by mating with as many different females as possible, there should be strong selection for males to move in search of mates. In agreement with our prediction, the percentage of fish that emigrated from release pools was higher for males than females (27.3% vs. 6.9%, respectively). Sex ratio was highly variable among pools and may influence a male's decision to emigrate or continue moving. We also detected a positive relationship between body length and the probability of emigration for males and a significant bias for upstream movement by males. Among the few females that did emigrate, a positive correlation was observed between body length and distance moved. Sex-biased movement appears to be related to mating systems in fishes, but the evidence is very limited. Given the implications for ecology, evolution, and conservation, future studies should explicitly address the influence of sex and mating systems on movement patterns.

  1. The thinker: opposing directionality of lighting bias within sculptural artwork.

    PubMed

    Sedgewick, Jennifer R; Weiers, Bradley; Stewart, Aaron; Elias, Lorin J

    2015-01-01

    Individuals tend to perceive the direction of light to come from above and slightly from the left; it has been speculated that this phenomenon is also producing similar lighting preferences within 2-dimensional artworks (e.g., paintings, advertisements). The purpose of the present study was to address if lighting bias was present in the 3-dimensional medium of sculpture by implementing a virtual art gallery lighting paradigm. Thirty-nine participants completed a computer task that consisted of 48 galleries each containing one sculpture (24 original sculptures, 24 mirror-reversed) which was surrounded by eight lights (above/below, left/right, front/back). Participants would select one light source to illuminate the sculpture in a manner they perceived to be the most aesthetically pleasing. The results indicated a significant preference for lights positioned from above and from the right, a finding that is contradictory to previous lighting bias research examining artworks. An interpretation for the rightward bias applies the perceptual concept of subjective lighting equality. Objects illuminated from the left typically appear brighter in comparison to right-side lighting; in sculpture, however, increased luminosity can reduce the sculptural detail, and may have been compensated via right-side lighting choices within the lighting task. PMID:25999840

  2. Quantifying Biogenic Bias in Screening Libraries

    PubMed Central

    Hert, Jérôme; Irwin, John J.; Laggner, Christian; Keiser, Michael J.; Shoichet, Brian K.

    2009-01-01

    In lead discovery, libraries of 106 molecules are screened for biological activity. Given the over 1060 drug-like molecules thought possible, such screens might never succeed. That they do, even occasionally, implies a biased selection of library molecules. Here a method is developed to quantify the bias in screening libraries towards biogenic molecules. With this approach, we consider what is missing from screening libraries and how they can be optimized. PMID:19483698

  3. Culturally Considerate School Counseling: Helping without Bias

    ERIC Educational Resources Information Center

    Anderson, Kim L.

    2010-01-01

    The author brings her counseling expertise, personal experience, and compassionate perspective to this practical resource that cultivates "cultural competence"--essential for work with diverse populations. Expanding the definition of culture, this book addresses how biases have evolved in new and challenging ways, and provides strategies to help…

  4. Estimating U.S. residential demand for fuelwood in the presence of selectivity

    NASA Astrophysics Data System (ADS)

    Daly, Ryan Michael

    Residential energy consumers have options for home heating. With many applications, appliances, and fuel types, fuelwood used for heating faces stiff competition in modern society from other fuels. This study estimates demand for domestic fuelwood. It also examines whether evidence of bias exists from residential homes choosing to use fuelwood. The use of OLS as an estimator will yield biased results if such selectivity exists. Selectivity is addressed with a Heckman (1979) two-step procedure; bias in fuelwood demand estimation using OLS is reduced. Non-wood energy prices and income are major determinants of fuelwood demand. Geographical regions and urbanization confirm results from prior studies.

  5. Detecting referral and selection bias by the anonymous linkage of practice, hospital and clinic data using Secure and Private Record Linkage (SAPREL): case study from the evaluation of the Improved Access to Psychological Therapy (IAPT) service

    PubMed Central

    2011-01-01

    Background The evaluation of demonstration sites set up to provide improved access to psychological therapies (IAPT) comprised the study of all people identified as having common mental health problems (CMHP), those referred to the IAPT service, and a sample of attenders studied in-depth. Information technology makes it feasible to link practice, hospital and IAPT clinic data to evaluate the representativeness of these samples. However, researchers do not have permission to browse and link these data without the patients' consent. Objective To demonstrate the use of a mixed deterministic-probabilistic method of secure and private record linkage (SAPREL) - to describe selection bias in subjects chosen for in-depth evaluation. Method We extracted, pseudonymised and used fuzzy logic to link multiple health records without the researcher knowing the patient's identity. The method can be characterised as a three party protocol mainly using deterministic algorithms with dynamic linking strategies; though incorporating some elements of probabilistic linkage. Within the data providers' safe haven we extracted: Demographic data, hospital utilisation and IAPT clinic data; converted post code to index of multiple deprivation (IMD); and identified people with CMHP. We contrasted the age, gender, ethnicity and IMD for the in-depth evaluation sample with people referred to IAPT, use hospital services, and the population as a whole. Results The in IAPT-in-depth group had a mean age of 43.1 years; CI: 41.0 - 45.2 (n = 166); the IAPT-referred 40.2 years; CI: 39.4 - 40.9 (n = 1118); and those with CMHP 43.6 years SEM 0.15. (n = 12210). Whilst around 67% of those with a CMHP were women, compared to 70% of those referred to IAPT, and 75% of those subject to in-depth evaluation (Chi square p < 0.001). The mean IMD score for the in-depth evaluation group was 36.6; CI: 34.2 - 38.9; (n = 166); of those referred to IAPT 38.7; CI: 37.9 - 39.6; (n = 1117); and of people with CMHP 37.6; CI 37

  6. Biased predecision processing.

    PubMed

    Brownstein, Aaron L

    2003-07-01

    Decision makers conduct biased predecision processing when they restructure their mental representation of the decision environment to favor one alternative before making their choice. The question of whether biased predecision processing occurs has been controversial since L. Festinger (1957) maintained that it does not occur. The author reviews relevant research in sections on theories of cognitive dissonance, decision conflict, choice certainty, action control, action phases, dominance structuring, differentiation and consolidation, constructive processing, motivated reasoning, and groupthink. Some studies did not find evidence of biased predecision processing, but many did. In the Discussion section, the moderators are summarized and used to assess the theories. PMID:12848220

  7. Variable addressability imaging systems

    NASA Astrophysics Data System (ADS)

    Kubala, Kenneth Scott

    The use of variable addressability for creating an optimum human-machine interface is investigated. Current wide field optical systems present more information to the human visual system than it has the capacity to perceive. The axial resolution, and/or the field of view can be increased by minimizing the difference between what the eye can perceive and what the system presents. The variable addressability function was developed through the use of a human factors experiment that characterized the position of the eye during the simulated use of a binocular system. Applying the variable addressability function to a conventional optical design required the development of a new metric for evaluating the expected performance of the variable addressability system. The new metric couples psycho-visual data and traditional optical data in order to specify the required performance of the variable addressability system. A non-linear mapping of the pixels is required in order to have the system work most efficiently with the human visual system, while also compensating for eye motion. The non-linear mapping function, which is the backbone of the variable addressability technique, can be created using optical distortion. The lens and system design is demonstrated in two different spectral bands. One of the designs was fabricated, tested, and assembled into a prototype. Through a second human factors study aimed at measuring performance, the variable addressability prototype was directly compared to a uniform addressability prototype, quantifying the difference in performance for the two prototypes. The human factors results showed that the variable addressability prototype provided better resolution 13% of the time throughout the experiment, but was 15% slower in use than the uniform addressability prototype.

  8. The Anti-Bias Approach in Early Childhood.

    ERIC Educational Resources Information Center

    Creaser, Barbara; Dau, Elizabeth

    This book on an anti-bias approach to early childhood education addresses aspects of diversity such as gender, race, and language within Australian society and provides strategies for working with families and staff to challenge existing attitudes and practices. Key features of the book include case studies showing anti-bias principles in action,…

  9. Bias-Related Incidents, Hate Crimes, and Conflict Resolution.

    ERIC Educational Resources Information Center

    Prutzman, Priscilla

    1994-01-01

    Examines the role of conflict resolution in addressing bias-related incidents and hate crimes. The author discusses how one organization, Children's Creative Response to Conflict, is working to teach conflict-resolution skills to students and teachers to reduce bias-related violence. Recommendations for the creation of bigotry-free school…

  10. Estimating Bias Error Distributions

    NASA Technical Reports Server (NTRS)

    Liu, Tian-Shu; Finley, Tom D.

    2001-01-01

    This paper formulates the general methodology for estimating the bias error distribution of a device in a measuring domain from less accurate measurements when a minimal number of standard values (typically two values) are available. A new perspective is that the bias error distribution can be found as a solution of an intrinsic functional equation in a domain. Based on this theory, the scaling- and translation-based methods for determining the bias error distribution arc developed. These methods are virtually applicable to any device as long as the bias error distribution of the device can be sufficiently described by a power series (a polynomial) or a Fourier series in a domain. These methods have been validated through computational simulations and laboratory calibration experiments for a number of different devices.

  11. Method for the electro-addressable functionalization of electrode arrays

    SciTech Connect

    Harper, Jason C.; Polsky, Ronen; Dirk, Shawn M.; Wheeler, David R.; Arango, Dulce C.; Brozik, Susan M.

    2015-12-15

    A method for preparing an electrochemical biosensor uses bias-assisted assembly of unreactive -onium molecules on an electrode array followed by post-assembly electro-addressable conversion of the unreactive group to a chemical or biological recognition group. Electro-addressable functionalization of electrode arrays enables the multi-target electrochemical sensing of biological and chemical analytes.

  12. Mechanism for and method of biasing magnetic sensor

    SciTech Connect

    Kautz, David R.

    2007-12-04

    A magnetic sensor package having a biasing mechanism involving a coil-generated, resistor-controlled magnetic field for providing a desired biasing effect. In a preferred illustrated embodiment, the package broadly comprises a substrate; a magnetic sensor element; a biasing mechanism, including a coil and a first resistance element; an amplification mechanism; a filter capacitor element; and an encapsulant. The sensor is positioned within the coil. A current applied to the coil produces a biasing magnetic field. The biasing magnetic field is controlled by selecting a resistance value for the first resistance element which achieves the desired biasing effect. The first resistance element preferably includes a plurality of selectable resistors, the selection of one or more of which sets the resistance value.

  13. Sources and consequences of hypothetical bias in economic analyses of risk behavior

    SciTech Connect

    Cantor, R.; Schoepfle, M. ); Szarleta, E. )

    1989-01-01

    Economic analyses are often used to address the tradeoffs people and constituencies face when selecting among alternative responses to risk changes. These analyses have become increasingly important in recent years as policy makers seek to understand what people will accept or give up to obtain a change in their exposure to risk from, for examples, an hazardous waste site, industrial plant, or biotechnological experiment. The literature on hypothetical bias indicates that the current elicitation techniques to investigate these tradeoffs are not sufficient to ensure meaningful responses to questions about risk preferences and intended behavior. A number of factors can influence the extent of hypothetical bias for a particular risk problem including the type of risk, language, who is affected, property rights, and the decision framework in which the risk problem is posed. We examine the major sources of hypothetical bias for the two predominant elicitation techniques in economics: contingent valuation and experimental economics. For each bias source, we discuss the possible consequences when interpreting the results of the technique, with a special focus on the policy context. We discuss how recent developments in psychology and cognitive anthropology can help mitigate many of the problems associated with hypothetical bias. To conclude, we identify the problems most likely to be resolved satisfactorily for scientific analysis and those that remain in need of further investigation. 38 refs.

  14. Addressing psychiatric comorbidity.

    PubMed

    Woody, G E; McLellan, A T; O'Brien, C P; Luborsky, L

    1991-01-01

    Research studies indicate that addressing psychiatric comorbidity can improve treatment for selected groups of substance-abusing patients. However, the chances for implementing the necessary techniques on a large scale are compromised by the absence of professional input and guidance within programs. This is especially true in public programs, which treat some of the most disadvantaged, disturbed, and socially destructive individuals in the entire mental health system. One starting point for upgrading the level of knowledge and training of staff members who work in this large treatment system could be to develop a better and more authoritative information dissemination network. Such a system exists in medicine; physicians are expected to read appropriate journals and to guide their treatment decisions using the data contained in the journals. Standards of practice and methods for modifying current practice are within the tradition of reading new facts, studying old ones, and comparing treatment outcome under different conditions with what is actually being done. No such general system of information-gathering or -sharing exists, particularly in public treatment programs. One of the most flagrant examples of this "educational shortfall" can be found among those methadone programs that adamantly insist on prescribing no more than 30 to 35 mg/day for all patients, in spite of the overwhelming evidence that these dose levels generally are inadequate. In some cases, program directors are unaware of studies that have shown the relationship between dose and outcome. In other cases, they are aware of the studies but do not modify their practices accordingly. This example of inadequate dosing is offered as an example of one situation that could be improved by adherence to a system of authoritative and systematic information dissemination. Many issues in substance abuse treatment do not lend themselves to information dissemination as readily as that of methadone dosing

  15. Political bias is tenacious.

    PubMed

    Ditto, Peter H; Wojcik, Sean P; Chen, Eric Evan; Grady, Rebecca Hofstein; Ringel, Megan M

    2015-01-01

    Duarte et al. are right to worry about political bias in social psychology but they underestimate the ease of correcting it. Both liberals and conservatives show partisan bias that often worsens with cognitive sophistication. More non-liberals in social psychology is unlikely to speed our convergence upon the truth, although it may broaden the questions we ask and the data we collect. PMID:26786070

  16. A normality bias in legal decision making.

    PubMed

    Prentice, Robert A; Koehler, Jonathan J

    2003-03-01

    It is important to understand how legal fact finders determine causation and assign blame. However, this process is poorly understood. Among the psychological factors that affect decision makers are an omission bias (a tendency to blame actions more than inactions [omissions] for bad results), and a normality bias (a tendency to react more strongly to bad outcomes that spring from abnormal rather than normal circumstances). The omission and normality biases often reinforce one another when inaction preserves the normal state and when action creates an abnormal state. But what happens when these biases push in opposite directions as they would when inaction promotes an abnormal state or when action promotes a normal state? Which bias exerts the stronger influence on the judgments and behaviors of legal decision makers? The authors address this issue in two controlled experiments. One experiment involves medical malpractice and the other involves stockbroker negligence. They find that jurors pay much more attention to the normality of conditions than to whether those conditions arose through acts or omissions. Defendants who followed a nontraditional medical treatment regime or who chose a nontraditional stock portfolio received more blame and more punishment for bad outcomes than did defendants who obtained equally poor results after recommending a traditional medical regime or a traditional stock portfolio. Whether these recommendations entailed an action or an omission was essentially irrelevant. The Article concludes with a discussion of the implications of a robust normality bias for American jurisprudence.

  17. Girl child and gender bias.

    PubMed

    Chowdhry, D P

    1995-01-01

    This article identifies gender bias against female children and youth in India. Gender bias is based on centuries-old religious beliefs and sayings from ancient times. Discrimination is reflected in denial or ignorance of female children's educational, health, nutrition, and recreational needs. Female infanticide and selective abortion of female fetuses are other forms of discrimination. The task of eliminating or reducing gender bias will involve legal, developmental, political, and administrative measures. Public awareness needs to be created. There is a need to reorient the education and health systems and to advocate for gender equality. The government of India set the following goals for the 1990s: to protect the survival of the girl child and practice safe motherhood; to develop the girl child in general; and to protect vulnerable girl children in different circumstances and in special groups. The Health Authorities should monitor the laws carefully to assure marriage after the minimum age, ban sex determination of the fetus, and monitor the health and nutrition of pre-school girls and nursing and pregnant mothers. Mothers need to be encouraged to breast feed, and to breast feed equally between genders. Every village and slum area needs a mini health center. Maternal mortality must decline. Primary health centers and hospitals need more women's wards. Education must be universally accessible. Enrollments should be increased by educating rural tribal and slum parents, reducing distances between home and school, making curriculum more relevant to girls, creating more female teachers, and providing facilities and incentives for meeting the needs of girl students. Supplementary income could be provided to families for sending girls to school. Recreational activities must be free of gender bias. Dowry, sati, and devdasi systems should be banned.

  18. Addressivity in cogenerative dialogues

    NASA Astrophysics Data System (ADS)

    Hsu, Pei-Ling

    2014-03-01

    Ashraf Shady's paper provides a first-hand reflection on how a foreign teacher used cogens as culturally adaptive pedagogy to address cultural misalignments with students. In this paper, Shady drew on several cogen sessions to showcase his journey of using different forms of cogens with his students. To improve the quality of cogens, one strategy he used was to adjust the number of participants in cogens. As a result, some cogens worked and others did not. During the course of reading his paper, I was impressed by his creative and flexible use of cogens and at the same time was intrigued by the question of why some cogens work and not others. In searching for an answer, I found that Mikhail Bakhtin's dialogism, especially the concept of addressivity, provides a comprehensive framework to address this question. In this commentary, I reanalyze the cogen episodes described in Shady's paper in the light of dialogism. My analysis suggests that addressivity plays an important role in mediating the success of cogens. Cogens with high addressivity function as internally persuasive discourse that allows diverse consciousnesses to coexist and so likely affords productive dialogues. The implications of addressivity in teaching and learning are further discussed.

  19. Composition strand asymmetries in prokaryotic genomes: mutational bias and biased gene orientation.

    PubMed

    Lopez, P; Philippe, H

    2001-03-01

    Most prokaryotic genomes display strand compositional asymmetries, but the reasons for these biases remain unclear. When the distribution of gene orientation is biased, as it often is, this may induce a bias in composition, as codon frequencies are not identical. We show here that this effect can be estimated and removed, and that the residual base skews are the highest at third base codon positions and lower at first and second positions. This strongly suggests that compositional asymmetries result from 1) a replication-related mutational bias that is filtered through selective pressure and/or from 2) an uneven distribution of gene orientation. In most cases, the mutational bias alters the codon usage and amino acid frequencies of the leading and the lagging strand. However, these features are not ubiquitous amongst prokaryotes, and the biological reasons for them remain to be found.

  20. Biases in Visual, Auditory, and Audiovisual Perception of Space.

    PubMed

    Odegaard, Brian; Wozny, David R; Shams, Ladan

    2015-12-01

    Localization of objects and events in the environment is critical for survival, as many perceptual and motor tasks rely on estimation of spatial location. Therefore, it seems reasonable to assume that spatial localizations should generally be accurate. Curiously, some previous studies have reported biases in visual and auditory localizations, but these studies have used small sample sizes and the results have been mixed. Therefore, it is not clear (1) if the reported biases in localization responses are real (or due to outliers, sampling bias, or other factors), and (2) whether these putative biases reflect a bias in sensory representations of space or a priori expectations (which may be due to the experimental setup, instructions, or distribution of stimuli). Here, to address these questions, a dataset of unprecedented size (obtained from 384 observers) was analyzed to examine presence, direction, and magnitude of sensory biases, and quantitative computational modeling was used to probe the underlying mechanism(s) driving these effects. Data revealed that, on average, observers were biased towards the center when localizing visual stimuli, and biased towards the periphery when localizing auditory stimuli. Moreover, quantitative analysis using a Bayesian Causal Inference framework suggests that while pre-existing spatial biases for central locations exert some influence, biases in the sensory representations of both visual and auditory space are necessary to fully explain the behavioral data. How are these opposing visual and auditory biases reconciled in conditions in which both auditory and visual stimuli are produced by a single event? Potentially, the bias in one modality could dominate, or the biases could interact/cancel out. The data revealed that when integration occurred in these conditions, the visual bias dominated, but the magnitude of this bias was reduced compared to unisensory conditions. Therefore, multisensory integration not only improves the

  1. Biases in Visual, Auditory, and Audiovisual Perception of Space.

    PubMed

    Odegaard, Brian; Wozny, David R; Shams, Ladan

    2015-12-01

    Localization of objects and events in the environment is critical for survival, as many perceptual and motor tasks rely on estimation of spatial location. Therefore, it seems reasonable to assume that spatial localizations should generally be accurate. Curiously, some previous studies have reported biases in visual and auditory localizations, but these studies have used small sample sizes and the results have been mixed. Therefore, it is not clear (1) if the reported biases in localization responses are real (or due to outliers, sampling bias, or other factors), and (2) whether these putative biases reflect a bias in sensory representations of space or a priori expectations (which may be due to the experimental setup, instructions, or distribution of stimuli). Here, to address these questions, a dataset of unprecedented size (obtained from 384 observers) was analyzed to examine presence, direction, and magnitude of sensory biases, and quantitative computational modeling was used to probe the underlying mechanism(s) driving these effects. Data revealed that, on average, observers were biased towards the center when localizing visual stimuli, and biased towards the periphery when localizing auditory stimuli. Moreover, quantitative analysis using a Bayesian Causal Inference framework suggests that while pre-existing spatial biases for central locations exert some influence, biases in the sensory representations of both visual and auditory space are necessary to fully explain the behavioral data. How are these opposing visual and auditory biases reconciled in conditions in which both auditory and visual stimuli are produced by a single event? Potentially, the bias in one modality could dominate, or the biases could interact/cancel out. The data revealed that when integration occurred in these conditions, the visual bias dominated, but the magnitude of this bias was reduced compared to unisensory conditions. Therefore, multisensory integration not only improves the

  2. Double propensity-score adjustment: A solution to design bias or bias due to incomplete matching.

    PubMed

    Austin, Peter C

    2014-07-17

    Propensity-score matching is frequently used to reduce the effects of confounding when using observational data to estimate the effects of treatments. Matching allows one to estimate the average effect of treatment in the treated. Rosenbaum and Rubin coined the term "bias due to incomplete matching" to describe the bias that can occur when some treated subjects are excluded from the matched sample because no appropriate control subject was available. The presence of incomplete matching raises important questions around the generalizability of estimated treatment effects to the entire population of treated subjects. We describe an analytic solution to address the bias due to incomplete matching. Our method is based on using optimal or nearest neighbor matching, rather than caliper matching (which frequently results in the exclusion of some treated subjects). Within the sample matched on the propensity score, covariate adjustment using the propensity score is then employed to impute missing potential outcomes under lack of treatment for each treated subject. Using Monte Carlo simulations, we found that the proposed method resulted in estimates of treatment effect that were essentially unbiased. This method resulted in decreased bias compared to caliper matching alone and compared to either optimal matching or nearest neighbor matching alone. Caliper matching alone resulted in design bias or bias due to incomplete matching, while optimal matching or nearest neighbor matching alone resulted in bias due to residual confounding. The proposed method also tended to result in estimates with decreased mean squared error compared to when caliper matching was used.

  3. Addressing Social Issues.

    ERIC Educational Resources Information Center

    Schoebel, Susan

    1991-01-01

    Maintains that advertising can help people become more aware of social responsibilities. Describes a successful nationwide newspaper advertising competition for college students in which ads address social issues such as literacy, drugs, teen suicide, and teen pregnancy. Notes how the ads have helped grassroots programs throughout the United…

  4. Addressing Sexual Harassment

    ERIC Educational Resources Information Center

    Young, Ellie L.; Ashbaker, Betty Y.

    2008-01-01

    This article discusses ways on how to address the problem of sexual harassment in schools. Sexual harassment--simply defined as any unwanted and unwelcome sexual behavior--is a sensitive topic. Merely providing students, parents, and staff members with information about the school's sexual harassment policy is insufficient; schools must take…

  5. Halo velocity bias

    NASA Astrophysics Data System (ADS)

    Biagetti, Matteo; Desjacques, Vincent; Kehagias, Alex; Riotto, Antonio

    2014-11-01

    It has been recently shown that any halo velocity bias present in the initial conditions does not decay to unity, in agreement with predictions from peak theory. However, this is at odds with the standard formalism based on the coupled-fluids approximation for the coevolution of dark matter and halos. Starting from conservation laws in phase space, we discuss why the fluid momentum conservation equation for the biased tracers needs to be modified in accordance with the change advocated in Baldauf et al. Our findings indicate that a correct description of the halo properties should properly take into account peak constraints when starting from the Vlasov-Boltzmann equation.

  6. Nanoscale content-addressable memory

    NASA Technical Reports Server (NTRS)

    Davis, Bryan (Inventor); Principe, Jose C. (Inventor); Fortes, Jose (Inventor)

    2009-01-01

    A combined content addressable memory device and memory interface is provided. The combined device and interface includes one or more one molecular wire crossbar memories having spaced-apart key nanowires, spaced-apart value nanowires adjacent to the key nanowires, and configurable switches between the key nanowires and the value nanowires. The combination further includes a key microwire-nanowire grid (key MNG) electrically connected to the spaced-apart key nanowires, and a value microwire-nanowire grid (value MNG) electrically connected to the spaced-apart value nanowires. A key or value MNGs selects multiple nanowires for a given key or value.

  7. Contextual Modulation of Biases in Face Recognition

    PubMed Central

    Felisberti, Fatima Maria; Pavey, Louisa

    2010-01-01

    Background The ability to recognize the faces of potential cooperators and cheaters is fundamental to social exchanges, given that cooperation for mutual benefit is expected. Studies addressing biases in face recognition have so far proved inconclusive, with reports of biases towards faces of cheaters, biases towards faces of cooperators, or no biases at all. This study attempts to uncover possible causes underlying such discrepancies. Methodology and Findings Four experiments were designed to investigate biases in face recognition during social exchanges when behavioral descriptors (prosocial, antisocial or neutral) embedded in different scenarios were tagged to faces during memorization. Face recognition, measured as accuracy and response latency, was tested with modified yes-no, forced-choice and recall tasks (N = 174). An enhanced recognition of faces tagged with prosocial descriptors was observed when the encoding scenario involved financial transactions and the rules of the social contract were not explicit (experiments 1 and 2). Such bias was eliminated or attenuated by making participants explicitly aware of “cooperative”, “cheating” and “neutral/indifferent” behaviors via a pre-test questionnaire and then adding such tags to behavioral descriptors (experiment 3). Further, in a social judgment scenario with descriptors of salient moral behaviors, recognition of antisocial and prosocial faces was similar, but significantly better than neutral faces (experiment 4). Conclusion The results highlight the relevance of descriptors and scenarios of social exchange in face recognition, when the frequency of prosocial and antisocial individuals in a group is similar. Recognition biases towards prosocial faces emerged when descriptors did not state the rules of a social contract or the moral status of a behavior, and they point to the existence of broad and flexible cognitive abilities finely tuned to minor changes in social context. PMID:20886086

  8. Own Variety Bias

    PubMed Central

    García, Andrea Ariza

    2015-01-01

    In a language identification task, native Belgian French and native Swiss French speakers identified French from France as their own variety. However, Canadian French was not subject to this bias. Canadian and French listeners didn’t claim a different variety as their own.

  9. Biased to Learn Language

    ERIC Educational Resources Information Center

    Sebastian-Galles, Nuria

    2007-01-01

    Some recent publications that explore the foundations of early language development are reviewed in this article. The review adopts the pivotal idea that infants' advancements are helped by the existence of different types of biases. The infant's discovery of the phonological properties of the language of the environment, as well as their learning…

  10. Optically biased laser gyro

    SciTech Connect

    Anderson, D.Z.; Chow, W.W.; Scully, M.O.; Sanders, V.E.

    1980-10-01

    We describe a four-mode ring laser that exhibits none of the mode-locking characteristics that plague laser gyros. This laser is characterized by a bias that changes sign with a change in the direction of rotation and prevents the counterpropagating modes from locking. A theoretical analysis explaining the experimental results is outlined.

  11. Own Variety Bias.

    PubMed

    Sloos, Marjoleine; García, Andrea Ariza

    2015-10-01

    In a language identification task, native Belgian French and native Swiss French speakers identified French from France as their own variety. However, Canadian French was not subject to this bias. Canadian and French listeners didn't claim a different variety as their own. PMID:27648211

  12. Test Bias: In God We Trust, All Others Must Have Data.

    ERIC Educational Resources Information Center

    Reynolds, Cecil R.

    The cultural test bias hypothesis represents the contention that all ethnic or racial group differences on mental tests are due to inherent, artifactual biases produced within the tests through flawed psychometric methodology. This address focuses on an empirical evaluation of the cultural test bias hypothesis, especially emphasizing the construct…

  13. Holographic content addressable storage

    NASA Astrophysics Data System (ADS)

    Chao, Tien-Hsin; Lu, Thomas; Reyes, George

    2015-03-01

    We have developed a Holographic Content Addressable Storage (HCAS) architecture. The HCAS systems consists of a DMD (Digital Micromirror Array) as the input Spatial Light Modulator (SLM), a CMOS (Complementary Metal-oxide Semiconductor) sensor as the output photodetector and a photorefractive crystal as the recording media. The HCAS system is capable of performing optical correlation of an input image/feature against massive reference data set stored in the holographic memory. Detailed system analysis will be reported in this paper.

  14. Provider Bias in Long-Acting Reversible Contraception (LARC) Promotion and Removal: Perceptions of Young Adult Women

    PubMed Central

    Kramer, Renee D.; Ryder, Kristin M.

    2016-01-01

    Long-acting reversible contraception (LARC) is effective and acceptable. However, concern exists about potential provider bias in LARC promotion. No study has documented contraceptive users’ attitudes toward or experiences with provider influence and bias regarding LARC. We collected qualitative data in 2014 to address this gap. Participants were 50 young adult women with any history of contraceptive use (including LARC) in Dane County, Wisconsin. Women often described providers as a trusted source of contraceptive information. However, several women reported that their preferences regarding contraceptive selection or removal were not honored. Furthermore, many participants believed that providers recommend LARC disproportionately to socially marginalized women. We encourage contraceptive counseling and removal protocols that directly address historical reproductive injustices and that honor patients’ wishes. PMID:27631741

  15. Divergent transducer-specific molecular efficacies generate biased agonism at a G protein-coupled receptor (GPCR).

    PubMed

    Strachan, Ryan T; Sun, Jin-peng; Rominger, David H; Violin, Jonathan D; Ahn, Seungkirl; Rojas Bie Thomsen, Alex; Zhu, Xiao; Kleist, Andrew; Costa, Tommaso; Lefkowitz, Robert J

    2014-05-16

    The concept of "biased agonism" arises from the recognition that the ability of an agonist to induce a receptor-mediated response (i.e. "efficacy") can differ across the multiple signal transduction pathways (e.g. G protein and β-arrestin (βarr)) emanating from a single GPCR. Despite the therapeutic promise of biased agonism, the molecular mechanism(s) whereby biased agonists selectively engage signaling pathways remain elusive. This is due in large part to the challenges associated with quantifying ligand efficacy in cells. To address this, we developed a cell-free approach to directly quantify the transducer-specific molecular efficacies of balanced and biased ligands for the angiotensin II type 1 receptor (AT1R), a prototypic GPCR. Specifically, we defined efficacy in allosteric terms, equating shifts in ligand affinity (i.e. KLo/KHi) at AT1R-Gq and AT1R-βarr2 fusion proteins with their respective molecular efficacies for activating Gq and βarr2. Consistent with ternary complex model predictions, transducer-specific molecular efficacies were strongly correlated with cellular efficacies for activating Gq and βarr2. Subsequent comparisons across transducers revealed that biased AT1R agonists possess biased molecular efficacies that were in strong agreement with the signaling bias observed in cellular assays. These findings not only represent the first measurements of the thermodynamic driving forces underlying differences in ligand efficacy between transducers but also support a molecular mechanism whereby divergent transducer-specific molecular efficacies generate biased agonism at a GPCR.

  16. Divergent transducer-specific molecular efficacies generate biased agonism at a G protein-coupled receptor (GPCR).

    PubMed

    Strachan, Ryan T; Sun, Jin-peng; Rominger, David H; Violin, Jonathan D; Ahn, Seungkirl; Rojas Bie Thomsen, Alex; Zhu, Xiao; Kleist, Andrew; Costa, Tommaso; Lefkowitz, Robert J

    2014-05-16

    The concept of "biased agonism" arises from the recognition that the ability of an agonist to induce a receptor-mediated response (i.e. "efficacy") can differ across the multiple signal transduction pathways (e.g. G protein and β-arrestin (βarr)) emanating from a single GPCR. Despite the therapeutic promise of biased agonism, the molecular mechanism(s) whereby biased agonists selectively engage signaling pathways remain elusive. This is due in large part to the challenges associated with quantifying ligand efficacy in cells. To address this, we developed a cell-free approach to directly quantify the transducer-specific molecular efficacies of balanced and biased ligands for the angiotensin II type 1 receptor (AT1R), a prototypic GPCR. Specifically, we defined efficacy in allosteric terms, equating shifts in ligand affinity (i.e. KLo/KHi) at AT1R-Gq and AT1R-βarr2 fusion proteins with their respective molecular efficacies for activating Gq and βarr2. Consistent with ternary complex model predictions, transducer-specific molecular efficacies were strongly correlated with cellular efficacies for activating Gq and βarr2. Subsequent comparisons across transducers revealed that biased AT1R agonists possess biased molecular efficacies that were in strong agreement with the signaling bias observed in cellular assays. These findings not only represent the first measurements of the thermodynamic driving forces underlying differences in ligand efficacy between transducers but also support a molecular mechanism whereby divergent transducer-specific molecular efficacies generate biased agonism at a GPCR. PMID:24668815

  17. Divergent Transducer-specific Molecular Efficacies Generate Biased Agonism at a G Protein-coupled Receptor (GPCR)*

    PubMed Central

    Strachan, Ryan T.; Sun, Jin-peng; Rominger, David H.; Violin, Jonathan D.; Ahn, Seungkirl; Rojas Bie Thomsen, Alex; Zhu, Xiao; Kleist, Andrew; Costa, Tommaso; Lefkowitz, Robert J.

    2014-01-01

    The concept of “biased agonism” arises from the recognition that the ability of an agonist to induce a receptor-mediated response (i.e. “efficacy”) can differ across the multiple signal transduction pathways (e.g. G protein and β-arrestin (βarr)) emanating from a single GPCR. Despite the therapeutic promise of biased agonism, the molecular mechanism(s) whereby biased agonists selectively engage signaling pathways remain elusive. This is due in large part to the challenges associated with quantifying ligand efficacy in cells. To address this, we developed a cell-free approach to directly quantify the transducer-specific molecular efficacies of balanced and biased ligands for the angiotensin II type 1 receptor (AT1R), a prototypic GPCR. Specifically, we defined efficacy in allosteric terms, equating shifts in ligand affinity (i.e. KLo/KHi) at AT1R-Gq and AT1R-βarr2 fusion proteins with their respective molecular efficacies for activating Gq and βarr2. Consistent with ternary complex model predictions, transducer-specific molecular efficacies were strongly correlated with cellular efficacies for activating Gq and βarr2. Subsequent comparisons across transducers revealed that biased AT1R agonists possess biased molecular efficacies that were in strong agreement with the signaling bias observed in cellular assays. These findings not only represent the first measurements of the thermodynamic driving forces underlying differences in ligand efficacy between transducers but also support a molecular mechanism whereby divergent transducer-specific molecular efficacies generate biased agonism at a GPCR. PMID:24668815

  18. Attention Bias toward Threat in Pediatric Anxiety Disorders

    ERIC Educational Resources Information Center

    Roy, Amy Krain; Vasa, Roma A.; Bruck, Maggie; Mogg, Karin; Bradley, Brendan P.; Sweeney, Michael; Bergman, R. Lindsey; McClure-Tone, Erin B.; Pine, Daniel S.

    2008-01-01

    Attention bias towards threat faces is examined for a large sample of anxiety-disordered youths using visual probe task. The results showed that anxious individuals showed a selective bias towards threat due to perturbation in neural mechanisms that control vigilance.

  19. SIZE BIAS AND DIFFERENTIAL LENSING OF STRONGLY LENSED, DUSTY GALAXIES IDENTIFIED IN WIDE-FIELD SURVEYS

    SciTech Connect

    Hezaveh, Yashar D.; Holder, Gilbert P.; Marrone, Daniel P.

    2012-12-10

    We address two selection effects that operate on samples of gravitationally lensed dusty galaxies identified in millimeter- and submillimeter-wavelength surveys. First, we point out the existence of a ''size bias'' in such samples: due to finite source effects, sources with higher observed fluxes are increasingly biased toward more compact objects. Second, we examine the effect of differential lensing in individual lens systems by modeling each source as a compact core embedded in an extended diffuse halo. Considering the ratio of magnifications in these two components, we find that at high overall magnifications, the compact component is amplified by a much larger factor than the diffuse component, but at intermediate magnifications ({approx}10) the probability of a larger magnification for the extended region is higher. Lens models determined from multi-frequency resolved imaging data are crucial to correct for this effect.

  20. The Adaptively Biased Molecular Dynamics method revisited: New capabilities and an application

    NASA Astrophysics Data System (ADS)

    Moradi, Mahmoud; Babin, Volodymyr; Roland, Christopher; Sagui, Celeste

    2015-09-01

    The free energy is perhaps one of the most important quantity required for describing biomolecular systems at equilibrium. Unfortunately, accurate and reliable free energies are notoriously difficult to calculate. To address this issue, we previously developed the Adaptively Biased Molecular Dynamics (ABMD) method for accurate calculation of rugged free energy surfaces (FES). Here, we briefly review the workings of the ABMD method with an emphasis on recent software additions, along with a short summary of a selected ABMD application based on the B-to-Z DNA transition. The ABMD method, along with current extensions, is currently implemented in the AMBER (ver.10-14) software package.

  1. Male-biased genes are overrepresented among novel Drosophila pseudoobscura sex-biased genes

    PubMed Central

    2008-01-01

    Background The origin of functional innovation is among the key questions in biology. Recently, it has been shown that new genes could arise from non-coding DNA and that such novel genes are often involved in male reproduction. Results With the aim of identifying novel genes, we used the technique "generation of longer cDNA fragments from serial analysis of gene expression (SAGE) tags for gene identification (GLGI)" to extend 84 sex-biased 3'end SAGE tags that previously could not be mapped to the D. pseudoobscura transcriptome. Eleven male-biased and 33 female-biased GLGI fragments were obtained, of which 5 male-biased and 3 female-biased tags corresponded to putatively novel genes. This excess of novel genes with a male-biased gene expression pattern is consistent with previous results, which found novel genes to be primarily expressed in male reproductive tissues. 5' RACE analysis indicated that these novel transcripts are very short in length and could contain introns. Interspecies comparisons revealed that most novel transcripts show evidence for purifying selection. Conclusion Overall, our data indicate that among sex-biased genes a considerable number of novel genes (~2–4%) exist in D. pseudoobscura, which could not be predicted based on D. melanogaster gene models. PMID:18577217

  2. Bioreactors Addressing Diabetes Mellitus

    PubMed Central

    Minteer, Danielle M.; Gerlach, Jorg C.

    2014-01-01

    The concept of bioreactors in biochemical engineering is a well-established process; however, the idea of applying bioreactor technology to biomedical and tissue engineering issues is relatively novel and has been rapidly accepted as a culture model. Tissue engineers have developed and adapted various types of bioreactors in which to culture many different cell types and therapies addressing several diseases, including diabetes mellitus types 1 and 2. With a rising world of bioreactor development and an ever increasing diagnosis rate of diabetes, this review aims to highlight bioreactor history and emerging bioreactor technologies used for diabetes-related cell culture and therapies. PMID:25160666

  3. Bioreactors addressing diabetes mellitus.

    PubMed

    Minteer, Danielle M; Gerlach, Jorg C; Marra, Kacey G

    2014-11-01

    The concept of bioreactors in biochemical engineering is a well-established process; however, the idea of applying bioreactor technology to biomedical and tissue engineering issues is relatively novel and has been rapidly accepted as a culture model. Tissue engineers have developed and adapted various types of bioreactors in which to culture many different cell types and therapies addressing several diseases, including diabetes mellitus types 1 and 2. With a rising world of bioreactor development and an ever increasing diagnosis rate of diabetes, this review aims to highlight bioreactor history and emerging bioreactor technologies used for diabetes-related cell culture and therapies.

  4. Content addressable memory project

    NASA Technical Reports Server (NTRS)

    Hall, J. Storrs; Levy, Saul; Smith, Donald E.; Miyake, Keith M.

    1992-01-01

    A parameterized version of the tree processor was designed and tested (by simulation). The leaf processor design is 90 percent complete. We expect to complete and test a combination of tree and leaf cell designs in the next period. Work is proceeding on algorithms for the computer aided manufacturing (CAM), and once the design is complete we will begin simulating algorithms for large problems. The following topics are covered: (1) the practical implementation of content addressable memory; (2) design of a LEAF cell for the Rutgers CAM architecture; (3) a circuit design tool user's manual; and (4) design and analysis of efficient hierarchical interconnection networks.

  5. Disentangling the relationship between sex-biased gene expression and X-linkage.

    PubMed

    Meisel, Richard P; Malone, John H; Clark, Andrew G

    2012-07-01

    X chromosomes are preferentially transmitted through females, which may favor the accumulation of X-linked alleles/genes with female-beneficial effects. Numerous studies have shown that genes with sex-biased expression are under- or over-represented on the X chromosomes of a wide variety of organisms. The patterns, however, vary between different animal species, and the causes of these differences are unresolved. Additionally, genes with sex-biased expression tend to be narrowly expressed in a limited number of tissues, and narrowly expressed genes are also non-randomly X-linked in a taxon-specific manner. It is therefore unclear whether the unique gene content of the X chromosome is the result of selection on genes with sex-biased expression, narrowly expressed genes, or some combination of the two. To address this problem, we measured sex-biased expression in multiple Drosophila species and at different developmental time points. These data were combined with available expression measurements from Drosophila melanogaster and mouse to reconcile the inconsistencies in X-chromosome content among taxa. Our results suggest that most of the differences between Drosophila and mammals are confounded by disparate data collection/analysis approaches as well as the correlation between sex bias and expression breadth. Both the Drosophila and mouse X chromosomes harbor an excess of genes with female-biased expression after controlling for the confounding factors, suggesting that the asymmetrical transmission of the X chromosome favors the accumulation of female-beneficial mutations in X-linked genes. However, some taxon-specific patterns remain, and we provide evidence that these are in part a consequence of constraints imposed by the dosage compensation mechanism in Drosophila.

  6. Understanding and minimizing epidemiologic bias in public health research.

    PubMed

    Choi, Bernard C K; Pak, Anita W P

    2005-01-01

    Awareness of potential biases is important for both researchers and policy-makers in public health: for researchers when designing and conducting studies, and for policy-makers when reading study reports and making decisions. This paper explains the meaning and importance of epidemiologic bias in public health and discusses how it arises and what can be done to minimize it. Examples of counting participants in a meeting, to which many policy-makers can relate, are used throughout the paper to illustrate bias in general, random error and systematic error, the effect of sample size, the three main categories of bias (selection, information and confounding), stratification and mathematical modeling.

  7. Temperature trend biases

    NASA Astrophysics Data System (ADS)

    Venema, Victor; Lindau, Ralf

    2016-04-01

    In an accompanying talk we show that well-homogenized national dataset warm more than temperatures from global collections averaged over the region of common coverage. In this poster we want to present auxiliary work about possible biases in the raw observations and on how well relative statistical homogenization can remove trend biases. There are several possible causes of cooling biases, which have not been studied much. Siting could be an important factor. Urban stations tend to move away from the centre to better locations. Many stations started inside of urban areas and are nowadays more outside. Even for villages the temperature difference between the centre and edge can be 0.5°C. When a city station moves to an airport, which often happened around WWII, this takes the station (largely) out of the urban heat island. During the 20th century the Stevenson screen was established as the dominant thermometer screen. This screen protected the thermometer much better against radiation than earlier designs. Deficits of earlier measurement methods have artificially warmed the temperatures in the 19th century. Newer studies suggest we may have underestimated the size of this bias. Currently we are in a transition to Automatic Weather Stations. The net global effect of this transition is not clear at this moment. Irrigation on average decreases the 2m-temperature by about 1 degree centigrade. At the same time, irrigation has increased significantly during the last century. People preferentially live in irrigated areas and weather stations serve agriculture. Thus it is possible that there is a higher likelihood that weather stations are erected in irrigated areas than elsewhere. In this case irrigation could lead to a spurious cooling trend. In the Parallel Observations Science Team of the International Surface Temperature Initiative (ISTI-POST) we are studying influence of the introduction of Stevenson screens and Automatic Weather Stations using parallel measurements

  8. Addressing Environmental Health Inequalities

    PubMed Central

    Gouveia, Nelson

    2016-01-01

    Environmental health inequalities refer to health hazards disproportionately or unfairly distributed among the most vulnerable social groups, which are generally the most discriminated, poor populations and minorities affected by environmental risks. Although it has been known for a long time that health and disease are socially determined, only recently has this idea been incorporated into the conceptual and practical framework for the formulation of policies and strategies regarding health. In this Special Issue of the International Journal of Environmental Research and Public Health (IJERPH), “Addressing Environmental Health Inequalities—Proceedings from the ISEE Conference 2015”, we incorporate nine papers that were presented at the 27th Conference of the International Society for Environmental Epidemiology (ISEE), held in Sao Paulo, Brazil, in 2015. This small collection of articles provides a brief overview of the different aspects of this topic. Addressing environmental health inequalities is important for the transformation of our reality and for changing the actual development model towards more just, democratic, and sustainable societies driven by another form of relationship between nature, economy, science, and politics. PMID:27618906

  9. Addressing Environmental Health Inequalities.

    PubMed

    Gouveia, Nelson

    2016-01-01

    Environmental health inequalities refer to health hazards disproportionately or unfairly distributed among the most vulnerable social groups, which are generally the most discriminated, poor populations and minorities affected by environmental risks. Although it has been known for a long time that health and disease are socially determined, only recently has this idea been incorporated into the conceptual and practical framework for the formulation of policies and strategies regarding health. In this Special Issue of the International Journal of Environmental Research and Public Health (IJERPH), "Addressing Environmental Health Inequalities-Proceedings from the ISEE Conference 2015", we incorporate nine papers that were presented at the 27th Conference of the International Society for Environmental Epidemiology (ISEE), held in Sao Paulo, Brazil, in 2015. This small collection of articles provides a brief overview of the different aspects of this topic. Addressing environmental health inequalities is important for the transformation of our reality and for changing the actual development model towards more just, democratic, and sustainable societies driven by another form of relationship between nature, economy, science, and politics. PMID:27618906

  10. Recursive bias estimation for high dimensional smoothers

    SciTech Connect

    Hengartner, Nicolas W; Matzner-lober, Eric; Cornillon, Pierre - Andre

    2008-01-01

    In multivariate nonparametric analysis, sparseness of the covariates also called curse of dimensionality, forces one to use large smoothing parameters. This leads to biased smoothers. Instead of focusing on optimally selecting the smoothing parameter, we fix it to some reasonably large value to ensure an over-smoothing of the data. The resulting smoother has a small variance but a substantial bias. In this paper, we propose to iteratively correct the bias initial estimator by an estimate of the latter obtained by smoothing the residuals. We examine in detail the convergence of the iterated procedure for classical smoothers and relate our procedure to L{sub 2}-Boosting. We apply our method to simulated and real data and show that our method compares favorably with existing procedures.

  11. Motion, identity and the bias toward agency

    PubMed Central

    Fields, Chris

    2014-01-01

    The well-documented human bias toward agency as a cause and therefore an explanation of observed events is typically attributed to evolutionary selection for a “social brain”. Based on a review of developmental and adult behavioral and neurocognitive data, it is argued that the bias toward agency is a result of the default human solution, developed during infancy, to the computational requirements of object re-identification over gaps in observation of more than a few seconds. If this model is correct, overriding the bias toward agency to construct mechanistic explanations of observed events requires structure-mapping inferences, implemented by the pre-motor action planning system, that replace agents with mechanisms as causes of unobserved changes in contextual or featural properties of objects. Experiments that would test this model are discussed. PMID:25191245

  12. Assessment of risk of bias in translational science

    PubMed Central

    2013-01-01

    Risk of bias in translational medicine may take one of three forms: A. a systematic error of methodology as it pertains to measurement or sampling (e.g., selection bias), B. a systematic defect of design that leads to estimates of experimental and control groups, and of effect sizes that substantially deviate from true values (e.g., information bias), and C. a systematic distortion of the analytical process, which results in a misrepresentation of the data with consequential errors of inference (e.g., inferential bias). Risk of bias can seriously adulterate the internal and the external validity of a clinical study, and, unless it is identified and systematically evaluated, can seriously hamper the process of comparative effectiveness and efficacy research and analysis for practice. The Cochrane Group and the Agency for Healthcare Research and Quality have independently developed instruments for assessing the meta-construct of risk of bias. The present article begins to discuss this dialectic. PMID:23927081

  13. Content addressable memory project

    NASA Technical Reports Server (NTRS)

    Hall, Josh; Levy, Saul; Smith, D.; Wei, S.; Miyake, K.; Murdocca, M.

    1991-01-01

    The progress on the Rutgers CAM (Content Addressable Memory) Project is described. The overall design of the system is completed at the architectural level and described. The machine is composed of two kinds of cells: (1) the CAM cells which include both memory and processor, and support local processing within each cell; and (2) the tree cells, which have smaller instruction set, and provide global processing over the CAM cells. A parameterized design of the basic CAM cell is completed. Progress was made on the final specification of the CPS. The machine architecture was driven by the design of algorithms whose requirements are reflected in the resulted instruction set(s). A few of these algorithms are described.

  14. Bax: Addressed to kill.

    PubMed

    Renault, Thibaud T; Manon, Stéphen

    2011-09-01

    The pro-apoptototic protein Bax (Bcl-2 Associated protein X) plays a central role in the mitochondria-dependent apoptotic pathway. In healthy mammalian cells, Bax is essentially cytosolic and inactive. Following a death signal, the protein is translocated to the outer mitochondrial membrane, where it promotes a permeabilization that favors the release of different apoptogenic factors, such as cytochrome c. The regulation of Bax translocation is associated to conformational changes that are under the control of different factors. The evidences showing the involvement of different Bax domains in its mitochondrial localization are presented. The interactions between Bax and its different partners are described in relation to their ability to promote (or prevent) Bax conformational changes leading to mitochondrial addressing and to the acquisition of the capacity to permeabilize the outer mitochondrial membrane. PMID:21641962

  15. Electrostatically biased binding of kinesin to microtubules.

    PubMed

    Grant, Barry J; Gheorghe, Dana M; Zheng, Wenjun; Alonso, Maria; Huber, Gary; Dlugosz, Maciej; McCammon, J Andrew; Cross, Robert A

    2011-11-01

    The minimum motor domain of kinesin-1 is a single head. Recent evidence suggests that such minimal motor domains generate force by a biased binding mechanism, in which they preferentially select binding sites on the microtubule that lie ahead in the progress direction of the motor. A specific molecular mechanism for biased binding has, however, so far been lacking. Here we use atomistic Brownian dynamics simulations combined with experimental mutagenesis to show that incoming kinesin heads undergo electrostatically guided diffusion-to-capture by microtubules, and that this produces directionally biased binding. Kinesin-1 heads are initially rotated by the electrostatic field so that their tubulin-binding sites face inwards, and then steered towards a plus-endwards binding site. In tethered kinesin dimers, this bias is amplified. A 3-residue sequence (RAK) in kinesin helix alpha-6 is predicted to be important for electrostatic guidance. Real-world mutagenesis of this sequence powerfully influences kinesin-driven microtubule sliding, with one mutant producing a 5-fold acceleration over wild type. We conclude that electrostatic interactions play an important role in the kinesin stepping mechanism, by biasing the diffusional association of kinesin with microtubules. PMID:22140358

  16. Electrostatically Biased Binding of Kinesin to Microtubules

    PubMed Central

    Zheng, Wenjun; Alonso, Maria; Huber, Gary; Dlugosz, Maciej; McCammon, J. Andrew; Cross, Robert A.

    2011-01-01

    The minimum motor domain of kinesin-1 is a single head. Recent evidence suggests that such minimal motor domains generate force by a biased binding mechanism, in which they preferentially select binding sites on the microtubule that lie ahead in the progress direction of the motor. A specific molecular mechanism for biased binding has, however, so far been lacking. Here we use atomistic Brownian dynamics simulations combined with experimental mutagenesis to show that incoming kinesin heads undergo electrostatically guided diffusion-to-capture by microtubules, and that this produces directionally biased binding. Kinesin-1 heads are initially rotated by the electrostatic field so that their tubulin-binding sites face inwards, and then steered towards a plus-endwards binding site. In tethered kinesin dimers, this bias is amplified. A 3-residue sequence (RAK) in kinesin helix alpha-6 is predicted to be important for electrostatic guidance. Real-world mutagenesis of this sequence powerfully influences kinesin-driven microtubule sliding, with one mutant producing a 5-fold acceleration over wild type. We conclude that electrostatic interactions play an important role in the kinesin stepping mechanism, by biasing the diffusional association of kinesin with microtubules. PMID:22140358

  17. Elementary School Basal Readers and Work Mode Bias

    ERIC Educational Resources Information Center

    Luker, William A.; And Others

    1974-01-01

    This study attempts to determine if quantitative and qualitative bias regarding work modes, specifically professional and paraprofesional vs. technical-vocational, exists in selected elementary school text materials. (Author/JH)

  18. Negativity bias and basic values.

    PubMed

    Schwartz, Shalom H

    2014-06-01

    Basic values explain more variance in political attitudes and preferences than other personality and sociodemographic variables. The values most relevant to the political domain are those likely to reflect the degree of negativity bias. Value conflicts that represent negativity bias clarify differences between what worries conservatives and liberals and suggest that relations between ideology and negativity bias are linear. PMID:24970450

  19. Racial bias shapes social reinforcement learning.

    PubMed

    Lindström, Björn; Selbing, Ida; Molapour, Tanaz; Olsson, Andreas

    2014-03-01

    Both emotional facial expressions and markers of racial-group belonging are ubiquitous signals in social interaction, but little is known about how these signals together affect future behavior through learning. To address this issue, we investigated how emotional (threatening or friendly) in-group and out-group faces reinforced behavior in a reinforcement-learning task. We asked whether reinforcement learning would be modulated by intergroup attitudes (i.e., racial bias). The results showed that individual differences in racial bias critically modulated reinforcement learning. As predicted, racial bias was associated with more efficiently learned avoidance of threatening out-group individuals. We used computational modeling analysis to quantitatively delimit the underlying processes affected by social reinforcement. These analyses showed that racial bias modulates the rate at which exposure to threatening out-group individuals is transformed into future avoidance behavior. In concert, these results shed new light on the learning processes underlying social interaction with racial-in-group and out-group individuals.

  20. [Keynote address: Climate change

    SciTech Connect

    Forrister, D.

    1994-12-31

    Broadly speaking, the climate issue is moving from talk to action both in the United States and internationally. While few nations have adopted strict controls or stiff new taxes, a number of them are developing action plans that are making clear their intention to ramp up activity between now and the year 2000... and beyond. There are sensible, economically efficient strategies to be undertaken in the near term that offer the possibility, in many countries, to avoid more draconian measures. These strategies are by-and-large the same measures that the National Academy of Sciences recommended in a 1991 report called, Policy Implications of Greenhouse Warming. The author thinks the Academy`s most important policy contribution was how it recommended the nations act in the face of uncertain science and high risks--that cost effective measures are adopted as cheap insurance... just as nations insure against other high risk, low certainty possibilities, like catastrophic health insurance, auto insurance, and fire insurance. This insurance theme is still right. First, the author addresses how the international climate change negotiations are beginning to produce insurance measures. Next, the author will discuss some of the key issues to watch in those negotiations that relate to longer-term insurance. And finally, the author will report on progress in the United States on the climate insurance plan--The President`s Climate Action Plan.

  1. The potential for social contextual and group biases in team decision-making: biases, conditions and psychological mechanisms.

    PubMed

    Jones, P E; Roelofsma, P H

    2000-08-01

    This paper provides a critical review of social contextual and group biases that are relevant to team decision-making in command and control situations. Motivated by the insufficient level of attention this area has received, the purpose of the paper is to provide an insight into the potential that these types of biases have to affect the decision-making of such teams. The biases considered are: false consensus, groupthink, group polarization and group escalation of commitment. For each bias the following four questions are addressed. What is the descriptive nature of the bias? What factors induce the bias? What psychological mechanisms underlie the bias? What is the relevance of the bias to command and control teams? The analysis suggests that these biases have a strong potential to affect team decisions. Consistent with the nature of team decision-making in command and control situations, all of the biases considered tend to be associated with those decisions that are important or novel and are promoted by time pressure and high levels of uncertainty. A concept unifying these biases is that of the shared mental model, but whereas false consensus emanates from social projection tendencies, the rest emanate from social influence factors. The authors also discuss the 'tricky' distinction between teams and groups and propose a revised definition for command and control team. Finally, the authors emphasize the need for future empirical research in this area to pay additional attention to the social side of cognition and the potential that social biases have to affect team decision-making.

  2. Estimating Production Potentials: Expert Bias in Applied Decision Making

    SciTech Connect

    L. J. Matthews; L. K. Burggraf; W. J. Reece

    1998-10-01

    A study was conducted to evaluate how workers predict manufacturing production potentials given positively and negatively framed information. Findings indicate the existence of a bias toward positive information and suggest that this bias may be reduced with experience but is never the less maintained. Experts err in the same way non experts do in differentially processing negative and positive information. Additionally, both experts and non experts tend to overestimate production potentials in a positive direction. The authors propose that these biases should be addressed with further research including cross domain analyses and consideration in training, workplace design, and human performance modeling.

  3. Racism and the Conspiracy of Silence: Presidential Address

    ERIC Educational Resources Information Center

    Sue, Derald Wing

    2005-01-01

    This presidential address focuses on a specific and daunting assumption about racism that many find disturbing--a belief that no one born and raised in the United States is free from inheriting the racial biases of their forebears. It states explicitly that it is impossible for anyone to not to have racist, sexist, and homophobic attitudes,…

  4. New Trends in Magnetic Exchange Bias

    NASA Astrophysics Data System (ADS)

    Mougin, Alexandra; Mangin, Stéphane; Bobo, Jean-Francois; Loidl, Alois

    2005-05-01

    of the constituant layers. The spirit of this topical issue is, for the first time, to gather and survey recent and original developments, both experimental and theoretical, which bring new insights into the physics of exchange bias. It has been planned in relation with an international workshop exclusively devoted to exchange bias, namely IWEBMN’04 (International Workshop on Exchange Bias in Magnetic Nanostructures) that took place in Anglet, in the south west of France, from 16th to 18th September 2004. The conference gathered worldwide researchers in the area, both experimentalists and theoreticians. Several research paths are particularly active in the field of magnetic exchange coupling. The conference, as well as this topical issue, which was also open to contributions from scientists not participating in the conference, has been organized according to the following principles: 1. Epitaxial systems: Since the essential behavior of exchange bias critically depends on the atomic-level chemical and spin structure at the interface between the ferromagnetic and antiferromagnetic components, epitaxial AF/F systems in which the quality of the interface and the crystalline coherence are optimized and well known are ideal candidates for a better understanding of the underlying physics of exchange bias. The dependence of exchange bias on the spin configurations at the interfaces can be accomplished by selecting different crystallographic orientations. The role of interface roughness can also be understood from thin-film systems by changing the growth parameters, and correlations between the interface structure and exchange bias can be made, as reported in this issue. 2. Out-of-plane magnetized systems: While much important work has been devoted to the study of structures with in-plane magnetization, little has been done on the study of exchange bias and exchange coupling in samples with out-of-plane magnetization. Some systems can exhibit either in-plane or out

  5. Molecular evolution of sex-biased genes in Drosophila.

    PubMed

    Zhang, Zhi; Hambuch, Tina M; Parsch, John

    2004-11-01

    Studies of morphology, interspecific hybridization, protein/DNA sequences, and levels of gene expression have suggested that sex-related characters (particularly those involved in male reproduction) evolve rapidly relative to non-sex-related characters. Here we report a general comparison of evolutionary rates of sex-biased genes using data from cDNA microarray experiments and comparative genomic studies of Drosophila. Comparisons of nonsynonymous/synonymous substitution rates (d(N)/d(S)) between species of the D. melanogaster subgroup revealed that genes with male-biased expression had significantly faster rates of evolution than genes with female-biased or unbiased expression. The difference was caused primarily by a higher d(N) in the male-biased genes. The same pattern was observed for comparisons among more distantly related species. In comparisons between D. melanogaster and D. pseudoobscura, genes with highly biased male expression were significantly more divergent than genes with highly biased female expression. In many cases, orthologs of D. melanogaster male-biased genes could not be identified in D. pseudoobscura through a Blast search. In contrast to the male-biased genes, there was no clear evidence for accelerated rates of evolution in female-biased genes, and most comparisons indicated a reduced rate of evolution in female-biased genes relative to unbiased genes. Male-biased genes did not show an increased ratio of nonsynonymous/synonymous polymorphism within D. melanogaster, and comparisons of polymorphism/divergence ratios suggest that the rapid evolution of male-biased genes is caused by positive selection.

  6. Is Prescreening Biased?

    ERIC Educational Resources Information Center

    Werbel, James; And Others

    1989-01-01

    Recruiters from 20 firms representing engineering, financial services, retailing, and sales reviewed student prescreening materials and provided lists of students for interviews. Comparison of students selected for interviews and students not selected suggests discrimination against Asians and a strong reliance on academic achievement in…

  7. A new bias scheme for a low power consumption ReRAM crossbar array

    NASA Astrophysics Data System (ADS)

    Sun, Wookyung; Choi, Sujin; Shin, Hyungsoon

    2016-08-01

    This paper proposes a new bias scheme for a crossbar array that can improve the power consumption and read margin. The concept of the newly proposed 5/12 bias scheme is to reduce the bias of the unselected cells for power consumption and the bias of half-selected cells for a reduced line voltage drop of the selected cell. In the 5/12 bias scheme, the unselected word line and bit line are biased to 5 × V app/12 and 7 × V app/12, respectively. The electrical characteristics of the 5/12 bias scheme are evaluated by HSPICE simulations and it is found that appropriate nonlinearity of selector can simultaneously achieve low power consumption and high read margin for 5/12 bias scheme.

  8. Gender Bias in Women

    ERIC Educational Resources Information Center

    Bynum, Gregory Lewis

    2014-01-01

    The philosophical anthropologist Dorothy Dinnerstein, in her 1976 work "The Mermaid and the Minotaur: Sexual Arrangements and Human Malaise," argued that in order for us to address the excesses of male-dominated rule in society (militarism, rapacious consumerism), we must attack the root cause of patriarchy--women's domination of early…

  9. The intentionality bias and schizotypy.

    PubMed

    Moore, J W; Pope, A

    2014-01-01

    The "intentionality bias" refers to our automatic tendency to judge other people's actions to be intentional. In this experiment we extended research on this effect in two key ways. First, we developed a novel nonlinguistic task for assessing the intentionality bias. This task used video stimuli of ambiguous movements. Second, we investigated the relationship between the strength of this bias and schizotypy (schizophrenia-like symptoms in healthy individuals). Our results showed that the intentionality bias was replicated for the video stimuli and also that this bias is stronger in those individuals scoring higher on the schizotypy rating scales. Overall these findings lend further support for the existence of the intentionality bias. We also discuss the possible relevance of these findings for our understanding of certain symptoms of schizophrenic illness.

  10. Row and column drivers for addressing full color and video rate antiferroelectric liquid crystal microdisplays

    NASA Astrophysics Data System (ADS)

    Sanchez-Pena, J. M.; Santos, J. I.; Manzanares, R.; Perez, I.; Urruchi, V.; Torres, J. C.

    2005-07-01

    Flat panel display technology constitutes the fastest growing segment of the semiconductor industry. Presently, the majority of display related research is focused on the application of electrooptic effects due to the ease and efficiency of molecular reorientation with an applied voltage. One such area of study is the surface stabilized ferroelectric liquid crystal (SSFLC) display, which has many advantages over conventional cathode ray tubes as well as other types of liquid crystal displays. Antiferroelectric liquid crystal (AFLC) displays have unique electrooptical properties such as tristate switching behaviour, fast response, intrinsic analogue grey scale and a wide viewing angle that lead these materials in very attractive candidates for their potential use in high-resolution flat panel displays and microdisplays for computers and TV. To become a competitive display technology, they should work at video frequency and give full colour and a significant number of the grey levels. These features depend on the AFLC material used in the display device as well as the addressing schemes employed. We present a new programmable driver for addressing passive matrix AFLC displays based on a microcontroller system. This prototype was built with commercial electronic subsystems and it is able to range voltage levels for the row selection of +/-40V and has a minimum time resolution of 5 microseconds to shape the frame complete (selection pulse, bias, well and reset slots). The driver can address a 16x160 pixels AFLC display. A grey scale will showed in a preliminary 4x4 pixels AFLC display by using this prototype.

  11. Accelerated evolution of morph-biased genes in pea aphids.

    PubMed

    Purandare, Swapna R; Bickel, Ryan D; Jaquiery, Julie; Rispe, Claude; Brisson, Jennifer A

    2014-08-01

    Phenotypic plasticity, the production of alternative phenotypes (or morphs) from the same genotype due to environmental factors, results in some genes being expressed in a morph-biased manner. Theoretically, these morph-biased genes experience relaxed selection, the consequence of which is the buildup of slightly deleterious mutations at these genes. Over time, this is expected to result in increased protein divergence at these genes between species and a signature of relaxed purifying selection within species. Here we test these theoretical expectations using morph-biased genes in the pea aphid, a species that produces multiple morphs via polyphenism. We find that morph-biased genes exhibit faster rates of evolution (in terms of dN/dS) relative to unbiased genes and that divergence generally increases with increasing morph bias. Further, genes with expression biased toward rarer morphs (sexual females and males) show faster rates of evolution than genes expressed in the more common morph (asexual females), demonstrating that the amount of time a gene spends being expressed in a morph is associated with its rate of evolution. And finally, we show that genes expressed in the rarer morphs experience decreased purifying selection relative to unbiased genes, suggesting that it is a relaxation of purifying selection that contributes to their faster rates of evolution. Our results provide an important empirical look at the impact of phenotypic plasticity on gene evolution.

  12. Evaluation of hydrologic components of community land model 4 and bias identification

    NASA Astrophysics Data System (ADS)

    Du, Enhao; Vittorio, Alan Di; Collins, William D.

    2016-06-01

    Runoff and soil moisture are two key components of the global hydrologic cycle that should be validated at local to global scales in Earth System Models (ESMs) used for climate projection. We have evaluated the runoff and surface soil moisture output by the Community Climate System Model (CCSM) along with 8 other models from the Coupled Model Intercomparison Project (CMIP5) repository using satellite soil moisture observations and stream gauge corrected runoff products. A series of Community Land Model (CLM) runs forced by reanalysis and coupled model outputs was also performed to identify atmospheric drivers of biases and uncertainties in the CCSM. Results indicate that surface soil moisture simulations tend to be positively biased in high latitude areas by most selected CMIP5 models except CCSM, FGOALS, and BCC, which share similar land surface model code. With the exception of GISS, runoff simulations by all selected CMIP5 models were overestimated in mountain ranges and in most of the Arctic region. In general, positive biases in CCSM soil moisture and runoff due to precipitation input error were offset by negative biases induced by temperature input error. Excluding the impact from atmosphere modeling, the global mean of seasonal surface moisture oscillation was out of phase compared to observations in many years during 1985-2004. The CLM also underestimated runoff in the Amazon, central Africa, and south Asia, where soils all have high clay content. We hypothesize that lack of a macropore flow mechanism is partially responsible for this underestimation. However, runoff was overestimated in the areas covered by volcanic ash soils (i.e., Andisols), which might be associated with poor soil porosity representation in CLM. Our results indicate that CCSM predictability of hydrology could be improved by addressing the compensating errors associated with precipitation and temperature and updating the CLM soil representation.

  13. Epistemological and ethical assessment of obesity bias in industrialized countries

    PubMed Central

    2011-01-01

    Bernard Lonergan's cognitive theory challenges us to raise questions about both the cognitive process through which obesity is perceived as a behaviour change issue and the objectivity of such a moral judgment. Lonergan's theory provides the theoretical tools to affirm that anti-fat discrimination, in the United States of America and in many industrialized countries, is the result of both a group bias that resists insights into the good of other groups and a general bias of anti-intellectualism that tends to set common sense against insights that require any thorough scientific analyses. While general bias diverts the public's attention away from the true aetiology of obesity, group bias sustains an anti-fat culture that subtly legitimates discriminatory practices and policies against obese people. Although anti-discrimination laws may seem to be a reasonable way of protecting obese and overweight individuals from discrimination, obesity bias can be best addressed by reframing the obesity debate from an environmental perspective from which tools and strategies to address both the social and individual determinants of obesity can be developed. Attention should not be concentrated on individuals' behaviour as it is related to lifestyle choices, without giving due consideration to the all-encompassing constraining factors which challenge the social and rational blindness of obesity bias. PMID:22177365

  14. Biased and G Protein-Independent Signaling of Chemokine Receptors

    PubMed Central

    Steen, Anne; Larsen, Olav; Thiele, Stefanie; Rosenkilde, Mette M.

    2014-01-01

    Biased signaling or functional selectivity occurs when a 7TM-receptor preferentially activates one of several available pathways. It can be divided into three distinct forms: ligand bias, receptor bias, and tissue or cell bias, where it is mediated by different ligands (on the same receptor), different receptors (with the same ligand), or different tissues or cells (for the same ligand–receptor pair). Most often biased signaling is differentiated into G protein-dependent and β-arrestin-dependent signaling. Yet, it may also cover signaling differences within these groups. Moreover, it may not be absolute, i.e., full versus no activation. Here we discuss biased signaling in the chemokine system, including the structural basis for biased signaling in chemokine receptors, as well as in class A 7TM receptors in general. This includes overall helical movements and the contributions of micro-switches based on recently published 7TM crystals and molecular dynamics studies. All three forms of biased signaling are abundant in the chemokine system. This challenges our understanding of “classic” redundancy inevitably ascribed to this system, where multiple chemokines bind to the same receptor and where a single chemokine may bind to several receptors – in both cases with the same functional outcome. The ubiquitous biased signaling confers a hitherto unknown specificity to the chemokine system with a complex interaction pattern that is better described as promiscuous with context-defined roles and different functional outcomes in a ligand-, receptor-, or cell/tissue-defined manner. As the low number of successful drug development plans implies, there are great difficulties in targeting chemokine receptors; in particular with regard to receptor antagonists as anti-inflammatory drugs. Un-defined and putative non-selective targeting of the complete cellular signaling system could be the underlying cause of lack of success. Therefore, biased ligands could be the solution

  15. The association between negative attention biases and symptoms of depression in a community sample of adolescents

    PubMed Central

    Murphy, Susannah E.; Lau, Jennifer Y.F.

    2015-01-01

    Adolescence is a vulnerable time for the onset of depression. Recent evidence from adult studies suggests not only that negative attention biases are correlated with symptoms of depression, but that reducing negative attention biases through training can in turn reduce symptomology. The role and plasticity of attention biases in adolescent depression, however, remains unclear. This study examines the association between symptoms of depression and attention biases, and whether such biases are modifiable, in a community sample of adolescents. We report data from 105 adolescents aged 13–17 who completed a dot-probe measure of attention bias before and after a single session of visual search-based cognitive bias modification training. This is the first study to find a significant association between negative attention biases and increased symptoms of depression in a community sample of adolescents. Contrary to expectations, we were unable to manipulate attention biases using a previously successful cognitive bias modification task. There were no significant effects of the training on positive affect and only modest effects of the training, identified in post-hoc analyses, were observed on negative affect. Our data replicate those from the adult literature, which suggest that adolescent depression is a disorder associated with negative attention biases, although we were unable to modify attention biases in our study. We identify numerous parameters of our methodology which may explain these null training effects, and which could be addressed in future cognitive bias modification studies of adolescent depression. PMID:26539335

  16. Lateral biases in aesthetic preferences: pictorial dimensions and neural mechanisms.

    PubMed

    Christman, S; Pinger, K

    1997-01-01

    Observers often prefer one orientation of a stimulus over its mirror image; these lateral biases are assumed to reflect aspects of the observer's neural organisation. However, the precise dimensions of pictorial organisation that influence these preferences, as well as the underlying neural mechanisms, are not clear. The present experiments addressed these issues by employing a stimulus set allowing for a factorial combination of three dimensions of pictorial organisation: Weight, Interest, and Directionality. Experiments 1 and 2 found that subjects exhibited robust and consistent preferences for stimuli with left-to-right directionality, especially for stimuli with left-biased interest; right-biased interest eliminated the preference for left-to-right directionality. The dimension of weight had little effect. Inter-task correlations from Experiment 3 suggested that this preference for left-to-right directionality (i) reflects a stable, underlying directional bias in perceptuo-motor processing, and (ii) is not related to individual differences in hemispheric activation.

  17. Investigating Assessment Bias for Constructed Response Explanation Tasks: Implications for Evaluating Performance Expectations for Scientific Practice

    NASA Astrophysics Data System (ADS)

    Federer, Meghan Rector

    Assessment is a key element in the process of science education teaching and research. Understanding sources of performance bias in science assessment is a major challenge for science education reforms. Prior research has documented several limitations of instrument types on the measurement of students' scientific knowledge (Liu et al., 2011; Messick, 1995; Popham, 2010). Furthermore, a large body of work has been devoted to reducing assessment biases that distort inferences about students' science understanding, particularly in multiple-choice [MC] instruments. Despite the above documented biases, much has yet to be determined for constructed response [CR] assessments in biology and their use for evaluating students' conceptual understanding of scientific practices (such as explanation). Understanding differences in science achievement provides important insights into whether science curricula and/or assessments are valid representations of student abilities. Using the integrative framework put forth by the National Research Council (2012), this dissertation aimed to explore whether assessment biases occur for assessment practices intended to measure students' conceptual understanding and proficiency in scientific practices. Using a large corpus of undergraduate biology students' explanations, three studies were conducted to examine whether known biases of MC instruments were also apparent in a CR instrument designed to assess students' explanatory practice and understanding of evolutionary change (ACORNS: Assessment of COntextual Reasoning about Natural Selection). The first study investigated the challenge of interpreting and scoring lexically ambiguous language in CR answers. The incorporation of 'multivalent' terms into scientific discourse practices often results in statements or explanations that are difficult to interpret and can produce faulty inferences about student knowledge. The results of this study indicate that many undergraduate biology majors

  18. Sequential biases in accumulating evidence

    PubMed Central

    Huggins, Richard; Dogo, Samson Henry

    2015-01-01

    Whilst it is common in clinical trials to use the results of tests at one phase to decide whether to continue to the next phase and to subsequently design the next phase, we show that this can lead to biased results in evidence synthesis. Two new kinds of bias associated with accumulating evidence, termed ‘sequential decision bias’ and ‘sequential design bias’, are identified. Both kinds of bias are the result of making decisions on the usefulness of a new study, or its design, based on the previous studies. Sequential decision bias is determined by the correlation between the value of the current estimated effect and the probability of conducting an additional study. Sequential design bias arises from using the estimated value instead of the clinically relevant value of an effect in sample size calculations. We considered both the fixed‐effect and the random‐effects models of meta‐analysis and demonstrated analytically and by simulations that in both settings the problems due to sequential biases are apparent. According to our simulations, the sequential biases increase with increased heterogeneity. Minimisation of sequential biases arises as a new and important research area necessary for successful evidence‐based approaches to the development of science. © 2015 The Authors. Research Synthesis Methods Published by John Wiley & Sons Ltd. PMID:26626562

  19. Decision-making heuristics and biases across the life span.

    PubMed

    Strough, Jonell; Karns, Tara E; Schlosnagle, Leo

    2011-10-01

    We outline a contextual and motivational model of judgment and decision-making (JDM) biases across the life span. Our model focuses on abilities and skills that correspond to deliberative, experiential, and affective decision-making processes. We review research that addresses links between JDM biases and these processes as represented by individual differences in specific abilities and skills (e.g., fluid and crystallized intelligence, executive functioning, emotion regulation, personality traits). We focus on two JDM biases-the sunk-cost fallacy (SCF) and the framing effect. We trace the developmental trajectory of each bias from preschool through middle childhood, adolescence, early adulthood, and later adulthood. We conclude that life-span developmental trajectories differ depending on the bias investigated. Existing research suggests relative stability in the framing effect across the life span and decreases in the SCF with age, including in later life. We highlight directions for future research on JDM biases across the life span, emphasizing the need for process-oriented research and research that increases our understanding of JDM biases in people's everyday lives.

  20. Biased ligands: pathway validation for novel GPCR therapeutics.

    PubMed

    Rominger, David H; Cowan, Conrad L; Gowen-MacDonald, William; Violin, Jonathan D

    2014-06-01

    G protein-coupled receptors (GPCRs), in recent years, have been shown to signal via multiple distinct pathways. Furthermore, biased ligands for some receptors can differentially stimulate or inhibit these pathways versus unbiased endogenous ligands or drugs. Biased ligands can be used to gain a deeper understanding of the molecular targets and cellular responses associated with a GPCR, and may be developed into therapeutics with improved efficacy, safety and/or tolerability. Here we review examples and approaches to pathway validation that establish the relevance and therapeutic potential of distinct pathways that can be selectively activated or blocked by biased ligands.

  1. Biased ligands: pathway validation for novel GPCR therapeutics.

    PubMed

    Rominger, David H; Cowan, Conrad L; Gowen-MacDonald, William; Violin, Jonathan D

    2014-06-01

    G protein-coupled receptors (GPCRs), in recent years, have been shown to signal via multiple distinct pathways. Furthermore, biased ligands for some receptors can differentially stimulate or inhibit these pathways versus unbiased endogenous ligands or drugs. Biased ligands can be used to gain a deeper understanding of the molecular targets and cellular responses associated with a GPCR, and may be developed into therapeutics with improved efficacy, safety and/or tolerability. Here we review examples and approaches to pathway validation that establish the relevance and therapeutic potential of distinct pathways that can be selectively activated or blocked by biased ligands. PMID:24834870

  2. Classifying sex biased congenital anomalies

    SciTech Connect

    Lubinsky, M.S.

    1997-03-31

    The reasons for sex biases in congenital anomalies that arise before structural or hormonal dimorphisms are established has long been unclear. A review of such disorders shows that patterning and tissue anomalies are female biased, and structural findings are more common in males. This suggests different gender dependent susceptibilities to developmental disturbances, with female vulnerabilities focused on early blastogenesis/determination, while males are more likely to involve later organogenesis/morphogenesis. A dual origin for some anomalies explains paradoxical reductions of sex biases with greater severity (i.e., multiple rather than single malformations), presumably as more severe events increase the involvement of an otherwise minor process with opposite biases to those of the primary mechanism. The cause for these sex differences is unknown, but early dimorphisms, such as differences in growth or presence of H-Y antigen, may be responsible. This model provides a useful rationale for understanding and classifying sex-biased congenital anomalies. 42 refs., 7 tabs.

  3. Pursuing Peace--"Enlisting Students in the Battle against Bias"

    ERIC Educational Resources Information Center

    Bradley, Elizabeth H.

    2007-01-01

    In communities all over the United States, issues of mistrust, anger, harassment, and bias often accompany the task of cultures learning to live together, and Lewiston, Maine, is no exception. Lewiston High School has recognized the potential conflict and addressed it in a forthright manner. The students have helped lead the way. This article…

  4. All-optical multibit address recognition at 20 Gb/s based on TOAD

    NASA Astrophysics Data System (ADS)

    Yan, Yumei; Wu, Jian; Lin, Jintong

    2005-04-01

    All-optical multibit address recognition at 20 Gb/s is demonstrated based on a special AND logic of terahertz optical asymmetric demultiplexer (TOAD). The semiconductor optical amplifier (SOA) used in the TOAD is biased at transparency status to accelerate the gain recovery. This is the highest bit rate that multibit address recognition is demonstrated with SOA-based interferometer. The experimental results show low pattern dependency. With this method, address recognition can be performed without separating address and payload beforehand.

  5. Investigations of potential bias in the estimation of lambda using Pradel's (1996) model for capture-recapture data

    USGS Publications Warehouse

    Hines, J.E.; Nichols, J.D.

    2002-01-01

    Pradel's (1996) temporal symmetry model permitting direct estimation and modelling of population growth rate, lambda sub i provides a potentially useful tool for the study of population dynamics using marked animals. Because of its recent publication date, the approach has not seen much use, and there have been virtually no investigations directed at robustness of the resulting estimators. Here we consider several potential sources of bias, all motivated by specific uses of this estimation approach. We consider sampling situations in which the study area expands with time and present an analytic expression for the bias in lambda hat sub i. We next consider trap response in capture probabilities and heterogeneous capture probabilities and compute large-sample and simulation-based approximations of resulting bias in lambda hat sub i. These approximations indicate that trap response is an especially important assumption violation that can produce substantial bias. Finally, we consider losses on capture and emphasize the importance of selecting the estimator for lambda sub i that is appropriate to the question being addressed. For studies based on only sighting and resighting data, Pradel's (1996) lambda hat prime sub i is the appropriate estimator.

  6. Investigations of potential bias in the estimation of u using Pradel's (1996) model for capture-recapture data

    USGS Publications Warehouse

    Hines, James E.; Nichols, James D.

    2002-01-01

    Pradel's (1996) temporal symmetry model permitting direct estimation and modelling of population growth rate, u i , provides a potentially useful tool for the study of population dynamics using marked animals. Because of its recent publication date, the approach has not seen much use, and there have been virtually no investigations directed at robustness of the resulting estimators. Here we consider several potential sources of bias, all motivated by specific uses of this estimation approach. We consider sampling situations in which the study area expands with time and present an analytic expression for the bias in u i We next consider trap response in capture probabilities and heterogeneous capture probabilities and compute large-sample and simulation-based approximations of resulting bias in u i . These approximations indicate that trap response is an especially important assumption violation that can produce substantial bias. Finally, we consider losses on capture and emphasize the importance of selecting the estimator for u i that is appropriate to the question being addressed. For studies based on only sighting and resighting data, Pradel's (1996) u i ' is the appropriate estimator.

  7. Cognitive Bias in Systems Verification

    NASA Technical Reports Server (NTRS)

    Larson, Steve

    2012-01-01

    Working definition of cognitive bias: Patterns by which information is sought and interpreted that can lead to systematic errors in decisions. Cognitive bias is used in diverse fields: Economics, Politics, Intelligence, Marketing, to name a few. Attempts to ground cognitive science in physical characteristics of the cognitive apparatus exceed our knowledge. Studies based on correlations; strict cause and effect is difficult to pinpoint. Effects cited in the paper and discussed here have been replicated many times over, and appear sound. Many biases have been described, but it is still unclear whether they are all distinct. There may only be a handful of fundamental biases, which manifest in various ways. Bias can effect system verification in many ways . Overconfidence -> Questionable decisions to deploy. Availability -> Inability to conceive critical tests. Representativeness -> Overinterpretation of results. Positive Test Strategies -> Confirmation bias. Debiasing at individual level very difficult. The potential effect of bias on the verification process can be managed, but not eliminated. Worth considering at key points in the process.

  8. Observational biases for transiting planets

    NASA Astrophysics Data System (ADS)

    Kipping, David M.; Sandford, Emily

    2016-09-01

    Observational biases distort our view of nature, such that the patterns we see within a surveyed population of interest are often unrepresentative of the truth we seek. Transiting planets currently represent the most informative data set on the ensemble properties of exoplanets within 1 AU of their star. However, the transit method is inherently biased due to both geometric and detection-driven effects. In this work, we derive the overall observational biases affecting the most basic transit parameters from first principles. By assuming a trapezoidal transit and using conditional probability, we infer the expected distribution of these terms both as a joint distribution and in a marginalized form. These general analytic results provide a baseline against which to compare trends predicted by mission-tailored injection/recovery simulations and offer a simple way to correct for observational bias. Our results explain why the observed population of transiting planets displays a non-uniform impact parameter distribution, with a bias towards near-equatorial geometries. We also find that the geometric bias towards observed planets transiting near periastron is attenuated by the longer durations which occur near apoastron. Finally, we predict that the observational bias with respect to ratio-of-radii is super-quadratic, scaling as (RP/R⋆)5/2, driven by an enhanced geometric transit probability and modestly longer durations.

  9. 'One mission accomplished, more important ones remain': commentary on Every-Palmer, S., Howick, J. (2014) How evidence-based medicine is failing due to biased trials and selective publication. Journal of Evaluation in Clinical Practice, 20 (6), 908-914.

    PubMed

    Wyer, Peter; da Silva, Suzana Alves

    2015-06-01

    Every-Palmer and Howick suggest that evidence-based medicine (EBM) is failing in its mission because of contamination of research by manufacturer and researcher-motivated bias and self-interest. They fail to define that mission and to distinguish between the EBM movement and the research enterprise it was developed to critique. An educational movement, EBM accomplished its mission to simplify and package clinical epidemiological concepts in a form accessible to clinical learners. Its wide adoption within educational circles fostered critical literacy among several generations of practitioners. Illumination of bias, subterfuge and incomplete reporting of research has been a strength of EBM. Increased uptake and use of clinical research within the health care system properly defines the failing mission that eludes Every-Palmer and Howick. Responsibility for failure to make progress towards its achievement is shared by virtually all relevant streams within the system, including policy, clinical guideline development, educational movements and the development of approaches to evidence synthesis. Discordance between the epistemological premises pervading today's research and health care community and the complex social processes that ultimately determine research use constitutes an important factor that must be addressed as part of a remedy. Enhanced emphasis on and demonstration of alternative approaches to research such as realism and realist synthesis and the momentum towards development of a learning health care system hold promise as guideposts for the rapidly evolving health care environment.

  10. 2015 ASHG Awards and Addresses

    PubMed Central

    2016-01-01

    Each year at the annual meeting of The American Society of Human Genetics (ASHG), addresses are given in honor of The Society and a number of award winners. A summary of each of these is given below. On the following pages, we have printed the presidential address and the addresses for the William Allan Award, the Curt Stern Award, and the Victor A. McKusick Leadership Award. Webcasts of these addresses, as well as those of many other presentations, can be found at http://www.ashg.org.

  11. Optimism bias and parental views on unintentional injuries and safety: improving anticipatory guidance in early childhood.

    PubMed

    Rosales, Paula Patricia; Allen, Patricia L Jackson

    2012-01-01

    The purpose of this integrative literature review is to improve anticipatory guidance in early childhood by reviewing the influence of optimism bias on parents' views about safety and beliefs about their children's risk for unintentional injuries. This article reviews the theory of optimism bias and recent research utilizing optimism bias to explain parental health-related behaviors. The three articles in this literature review find a link between optimism bias and parents' failure to implement safety behaviors. Currently, there is no tool to measure a parent's level of optimism bias concerning the risk of unintentional injury to his or her child. It is important for primary care providers to try and identify optimism bias in parents and address it as a barrier to implementation of safety recommendations. More research should be dedicated to developing screening tools to identify optimism bias in parents and interventions to help them accept their children's vulnerability.

  12. Investigator Bias and Theory-Ladenness in Cross-Cultural Research: Insights from Wittgenstein

    ERIC Educational Resources Information Center

    Tan, Charlene

    2016-01-01

    A relatively under-explored topic in the current literature on and methods for research in the field of comparative and international education is the problem of investigator bias in cross-cultural research. This article discusses the nature of and an approach to address investigator bias in research that originates from the theory-ladenness of…

  13. Sustainability of Teacher Expectation Bias Effects on Long-Term Student Performance

    ERIC Educational Resources Information Center

    de Boer, Hester; Bosker, Roel J.; van der Werf, Margaretha P. C.

    2010-01-01

    In this article, we address the relationship between teacher expectation bias and student characteristics, its effect on long-term student performance, and the development of this effect over time. Expectation bias was defined as the difference between observed and predicted teacher expectation. These predicted expectations were estimated from a…

  14. Sex Bias and Work. Module 3. Choosing Occupations and Life Roles.

    ERIC Educational Resources Information Center

    Pfiffner, Karen J.

    This module on sex bias and work, the last in a series of three volumes of sex-fair career guidance activities, deals with choosing occupations and life roles. Addressed in the module are 16 learning activities that cover many of the sex-bias-related obstacles, both attitudinal and occupational, that students will be facing upon entering the world…

  15. The intentionality bias in schizophrenia.

    PubMed

    Peyroux, Elodie; Strickland, Brent; Tapiero, Isabelle; Franck, Nicolas

    2014-11-30

    The tendency to over-interpret events of daily life as resulting from voluntary or intentional actions is one of the key aspects of schizophrenia with persecutory delusions. Here, we ask whether this characteristic may emerge from the abnormal activity of a basic cognitive process found in healthy adults and children: the intentionality bias, which refers to the implicit and automatic inclination to interpret human actions as intentional (Rosset, 2008, Cognition 108, 771-780). In our experiment, patients with schizophrenia and healthy controls were shown sentences describing human actions in various linguistic contexts, and were asked to indicate whether the action was intentional or not. The results indicated that people with schizophrenia exhibited a striking bias to over attribute intentionality regardless of linguistic context, contrary to healthy controls who did not exhibit such a general intentionality bias. Moreover, this study provides some insight into the cognitive mechanisms underlying this bias: an inability to inhibit the automatic attribution of intentionality.

  16. Magnetic bearings with zero bias

    NASA Technical Reports Server (NTRS)

    Brown, Gerald V.; Grodsinsky, Carlos M.

    1991-01-01

    A magnetic bearing operating without a bias field has supported a shaft rotating at speeds up to 12,000 rpm with the usual four power supplies and with only two. A magnetic bearing is commonly operated with a bias current equal to half of the maximum current allowable in its coils. This linearizes the relation between net force and control current and improves the force slewing rate and hence the band width. The steady bias current dissipates power, even when no force is required from the bearing. The power wasted is equal to two-thirds of the power at maximum force output. Examined here is the zero bias idea. The advantages and disadvantages are noted.

  17. Reflecting Equity and Diversity. Part I: Guidelines and Procedure for Evaluating Bias in Instructional Materials. Part II: Bias Awareness Training Worksheets. Part III: Bias Awareness and Procedure Training Course.

    ERIC Educational Resources Information Center

    Bebermeyer, Jim; Edmond, Mary, Ed.

    Reflecting a need to prepare students for working in diverse organizations, this document was developed to increase school officials' awareness of bias in instructional materials and help them select bias-free materials. A number of the examples illustrate situations dealing with diversity in the workplace. The guide is divided into three parts:…

  18. Residualization is not the answer: Rethinking how to address multicollinearity.

    PubMed

    York, Richard

    2012-11-01

    Here I show that a commonly used procedure to address problems stemming from collinearity and multicollinearity among independent variables in regression analysis, "residualization", leads to biased coefficient and standard error estimates and does not address the fundamental problem of collinearity, which is a lack of information. I demonstrate this using visual representations of collinearity, hypothetical experimental designs, and analyses of both artificial and real world data. I conclude by noting the importance of examining methodological practices to ensure that their validity can be established based on rational criteria.

  19. Nanoscopic oxidation of p-type and un-doped Si (100) surfaces using un-externally biased atomic force microscope tips (AFM) in the presence of selected organic solvents

    NASA Astrophysics Data System (ADS)

    McCausland, Jeffrey; Withanage, Sajeevi; Mallik, Robert; Lyuksyutov, Sergei

    A conductive un-biased AFM tip oscillating above p-type or un-doped Si (100) treated with toluene, butan-2-ol, and propan-2-ol creates nanostructures ranging in height from 1-100 nm. The tip was oscillated in ambient conditions (30-70% Rel. Humidity) at frequencies in the 102 kHz range. It was repeatable with various concentrations of solvent in aqueous solution. It is suggested that mechanical oscillations of the AFM tip polarizes the solvent molecules deposited on the surface resulting in electron transfer from the tip to the surface followed by feature formation. This process effectively creates an electrochemical cell at the microscopic level and the miscibility of the solvents is the key to enabling the process. Species which ionize during the process may be consumed in irreversible reactions whereas the alcohols act as catalysts and are not consumed. The influence of boron defects in the Si substrates is also discussed. It appears that the observed oxidation is different from all other similar reported phenomena including local anodic oxidation, and chemo-mechanical lithographic techniques utilizing AFM.

  20. New Trends in Magnetic Exchange Bias

    NASA Astrophysics Data System (ADS)

    Mougin, Alexandra; Mangin, Stéphane; Bobo, Jean-Francois; Loidl, Alois

    2005-05-01

    of the constituant layers. The spirit of this topical issue is, for the first time, to gather and survey recent and original developments, both experimental and theoretical, which bring new insights into the physics of exchange bias. It has been planned in relation with an international workshop exclusively devoted to exchange bias, namely IWEBMN’04 (International Workshop on Exchange Bias in Magnetic Nanostructures) that took place in Anglet, in the south west of France, from 16th to 18th September 2004. The conference gathered worldwide researchers in the area, both experimentalists and theoreticians. Several research paths are particularly active in the field of magnetic exchange coupling. The conference, as well as this topical issue, which was also open to contributions from scientists not participating in the conference, has been organized according to the following principles: 1. Epitaxial systems: Since the essential behavior of exchange bias critically depends on the atomic-level chemical and spin structure at the interface between the ferromagnetic and antiferromagnetic components, epitaxial AF/F systems in which the quality of the interface and the crystalline coherence are optimized and well known are ideal candidates for a better understanding of the underlying physics of exchange bias. The dependence of exchange bias on the spin configurations at the interfaces can be accomplished by selecting different crystallographic orientations. The role of interface roughness can also be understood from thin-film systems by changing the growth parameters, and correlations between the interface structure and exchange bias can be made, as reported in this issue. 2. Out-of-plane magnetized systems: While much important work has been devoted to the study of structures with in-plane magnetization, little has been done on the study of exchange bias and exchange coupling in samples with out-of-plane magnetization. Some systems can exhibit either in-plane or out

  1. Biases In A Magnitude Limited Versus A Distant Limited Planet Search

    NASA Technical Reports Server (NTRS)

    Koch, David; Borucki, William; Witteborn, Fred C. (Technical Monitor)

    1996-01-01

    All methods utilized to conduct a search or survey inevitably have some built-in biases. These biases are often traced to some limitation of the instrument used or some inherent character of the signal being recorded. We address these limitations for various methods used or proposed for planet detection: spectroscopy, astrometry, interferometry, and photometry. For spectroscopy, the turbulence in the photosphere limits the minimum measurable dossier velocity to 3 m/s and hence the minimum planet to star mass ratio, thereby favoring massive close-in planets. Limited available observing time will necessarily introduce additional selection biases in the targets observed and telescope aperture will limit the faintest magnitude stars to be measured; For astrometry, the angular resolution of the instrument along with motions in the photometric center of the star limit the furthest distance for which giant planets can be detected to about 10 pc and favor massive outer orbit planets around low mass non-solar like stars; For imaging interferometry, the minimum angular size of the central null limits both the distance to the star and closeness of the planet to the host star to about 1 AU at 10 pc and thus to the very few solar-like stars within 10 pc. Solar and extra-solar zodiacal emission will limit the minimum size of the detectable planet. For photometry, the inherent variability of the star does not limit the minimum planet size until earth-sized or smaller planets are considered around solar-like stars. The telescope aperture limits the faintest stars that can be monitored. As with spectroscopy, there is no inherent distant limit to the method. After addressing the limiting factors of each method, an estimate is made of the number of planets of various sizes that could be found for each stellar type based on the detection probability and the number of stars that can be searched for planets.

  2. [Bias and confounding: pharmacoepidemiological study using administrative database].

    PubMed

    Nojiri, Shuko

    2015-01-01

    The provision of health care frequently creates digitalized data such as hospital-based electronic data, medication prescription records, and claims data collectively termed "administrative database research". The data source and analytical opportunities for study create risks that can lead to misinterpretation or bias the results. This review serves as an introduction to the concept of bias and confounding to help researchers conduct methodologically sound pharmacoepidemiologic research projects using administrative databases. Beyond general considerations for observational study, there are several unique issues related to database research that should be addressed. The risks of uninterpretable or biased results can be minimized by: providing a robust description of the data tables used; focusing on why and how they were created; measuring and reporting the accuracy of diagnostic and procedural codes used; and properly accounting for any time-dependent nature of variables. The hallmark of good research is rigorously careful analysis and interpretation. The promise for value of real world evidence using databases in medical decision making must be balanced against concerns related to observational inherited limitations for bias and confounding. Researchers should aim to avoid bias in the design of a study, adjust for confounding, and discuss the effects of residual bias on the results. PMID:26028416

  3. Decision-making heuristics and biases across the life span

    PubMed Central

    Strough, JoNell; Karns, Tara E.; Schlosnagle, Leo

    2013-01-01

    We outline a contextual and motivational model of judgment and decision-making (JDM) biases across the life span. Our model focuses on abilities and skills that correspond to deliberative, experiential, and affective decision-making processes. We review research that addresses links between JDM biases and these processes as represented by individual differences in specific abilities and skills (e.g., fluid and crystallized intelligence, executive functioning, emotion regulation, personality traits). We focus on two JDM biases—the sunk-cost fallacy (SCF) and the framing effect. We trace the developmental trajectory of each bias from preschool through middle childhood, adolescence, early adulthood, and later adulthood. We conclude that life-span developmental trajectories differ depending on the bias investigated. Existing research suggests relative stability in the framing effect across the life span and decreases in the SCF with age, including in later life. We highlight directions for future research on JDM biases across the life span, emphasizing the need for process-oriented research and research that increases our understanding of JDM biases in people’s everyday lives. PMID:22023568

  4. Attention Training and the Threat Bias: An ERP Study

    PubMed Central

    O’Toole, Laura; Dennis, Tracy A.

    2011-01-01

    Anxiety is characterized by exaggerated attention to threat. Several studies suggest that this threat bias plays a causal role in the development and maintenance of anxiety disorders. Furthermore, although the threat bias can be reduced in anxious individuals and induced in non-anxious individual, the attentional mechanisms underlying these changes remain unclear. To address this issue, 49 non-anxious adults were randomly assigned to either attentional training toward or training away from threat using a modified version of the dot probe task. Behavioral measures of attentional biases were also generated pre- and post-training using the dot probe task. Event-related potentials (ERPs) were generated to threat and non-threat face pairs and probes during pre- and post-training assessments. Effects of training on behavioral measures of the threat bias were significant, but only for those participants showing pre-training biases. Attention training also influenced early spatial attention, as measured by post-training P1 amplitudes to cues. Results illustrate the importance of taking pre-training attention biases in non-anxious individuals into account when evaluating the effects of attention training and tracking physiological changes in attention following training. PMID:22083026

  5. Efficient bias correction for magnetic resonance image denoising.

    PubMed

    Mukherjee, Partha Sarathi; Qiu, Peihua

    2013-05-30

    Magnetic resonance imaging (MRI) is a popular radiology technique that is used for visualizing detailed internal structure of the body. Observed MRI images are generated by the inverse Fourier transformation from received frequency signals of a magnetic resonance scanner system. Previous research has demonstrated that random noise involved in the observed MRI images can be described adequately by the so-called Rician noise model. Under that model, the observed image intensity at a given pixel is a nonlinear function of the true image intensity and of two independent zero-mean random variables with the same normal distribution. Because of such a complicated noise structure in the observed MRI images, denoised images by conventional denoising methods are usually biased, and the bias could reduce image contrast and negatively affect subsequent image analysis. Therefore, it is important to address the bias issue properly. To this end, several bias-correction procedures have been proposed in the literature. In this paper, we study the Rician noise model and the corresponding bias-correction problem systematically and propose a new and more effective bias-correction formula based on the regression analysis and Monte Carlo simulation. Numerical studies show that our proposed method works well in various applications. PMID:23074149

  6. Bias and design in software specifications

    NASA Technical Reports Server (NTRS)

    Straub, Pablo A.; Zelkowitz, Marvin V.

    1990-01-01

    Implementation bias in a specification is an arbitrary constraint in the solution space. Presented here is a model of bias in software specifications. Bias is defined in terms of the specification process and a classification of the attributes of the software product. Our definition of bias provides insight into both the origin and the consequences of bias. It also shows that bias is relative and essentially unavoidable. Finally, we describe current work on defining a measure of bias, formalizing our model, and relating bias to software defects.

  7. Demand artifact: objectively detecting biased participants in advertising research.

    PubMed

    Miller, Felicia; Schertzer, Susan

    2014-12-01

    Detecting and reducing the effect of biased participants continues to be an important task for researchers. However, the lack of objective measures to assess demand artifact has made it difficult to effectively address this issue. This paper reports two experiments that apply a theory-based post-experimental inquiry that can systematically identify biased participants in consumer research. The results demonstrate how easily and effectively researchers can incorporate this tool into experimental studies of all types and reduce the likelihood of systematic error.

  8. Demand artifact: objectively detecting biased participants in advertising research.

    PubMed

    Miller, Felicia; Schertzer, Susan

    2014-12-01

    Detecting and reducing the effect of biased participants continues to be an important task for researchers. However, the lack of objective measures to assess demand artifact has made it difficult to effectively address this issue. This paper reports two experiments that apply a theory-based post-experimental inquiry that can systematically identify biased participants in consumer research. The results demonstrate how easily and effectively researchers can incorporate this tool into experimental studies of all types and reduce the likelihood of systematic error. PMID:25486509

  9. Cognitive Biases Questionnaire for Psychosis

    PubMed Central

    Peters, Emmanuelle R.

    2014-01-01

    Objective: The Cognitive Biases Questionnaire for psychosis (CBQp) was developed to capture 5 cognitive distortions (jumping to conclusions, intentionalising, catastrophising, emotional reasoning, and dichotomous thinking), which are considered important for the pathogenesis of psychosis. Vignettes were adapted from the Cognitive Style Test (CST),1 relating to “Anomalous Perceptions” and “Threatening Events” themes. Method: Scale structure, reliability, and validity were investigated in a psychosis group, and CBQp scores were compared with those of depressed and healthy control samples. Results: The CBQp showed good internal consistency and test-retest reliability. The 5 biases were not independent, with a 2-related factor scale providing the best fit. This structure suggests that the CBQp assesses a general thinking bias rather than distinct cognitive errors, while Anomalous Perception and Threatening Events theme scores can be used separately. Total CBQp scores showed good convergent validity with the CST, but individual biases were not related to existing tasks purporting to assess similar reasoning biases. Psychotic and depressed populations scored higher than healthy controls, and symptomatic psychosis patients scored higher than their nonsymptomatic counterparts, with modest relationships between CBQp scores and symptom severity once emotional disorders were partialled out. Anomalous Perception theme and Intentionalising bias scores showed some specificity to psychosis. Conclusions: Overall, the CBQp has good psychometric properties, although it is likely that it measures a different construct to existing tasks, tentatively suggested to represent a bias of interpretation rather than reasoning, judgment or decision-making processes. It is a potentially useful tool in both research and clinical arenas. PMID:23413104

  10. Addressing adolescent pregnancy with legislation.

    PubMed

    Montgomery, Tiffany M; Folken, Lori; Seitz, Melody A

    2014-01-01

    Adolescent pregnancy is a concern among many women's health practitioners. While it is practical and appropriate to work to prevent adolescent pregnancy by educating adolescents in health care clinics, schools and adolescent-friendly community-based organizations, suggesting and supporting legislative efforts to reduce adolescent pregnancy can help address the issue on an even larger scale. This article aims to help nurses better understand current legislation that addresses adolescent pregnancy, and to encourage support of future adolescent pregnancy prevention legislation. PMID:25145716

  11. Addressing adolescent pregnancy with legislation.

    PubMed

    Montgomery, Tiffany M; Folken, Lori; Seitz, Melody A

    2014-01-01

    Adolescent pregnancy is a concern among many women's health practitioners. While it is practical and appropriate to work to prevent adolescent pregnancy by educating adolescents in health care clinics, schools and adolescent-friendly community-based organizations, suggesting and supporting legislative efforts to reduce adolescent pregnancy can help address the issue on an even larger scale. This article aims to help nurses better understand current legislation that addresses adolescent pregnancy, and to encourage support of future adolescent pregnancy prevention legislation.

  12. Addressing Statistical Biases in Nucleotide-Derived Protein Databases for Proteogenomic Search Strategies

    PubMed Central

    2012-01-01

    Proteogenomics has the potential to advance genome annotation through high quality peptide identifications derived from mass spectrometry experiments, which demonstrate a given gene or isoform is expressed and translated at the protein level. This can advance our understanding of genome function, discovering novel genes and gene structure that have not yet been identified or validated. Because of the high-throughput shotgun nature of most proteomics experiments, it is essential to carefully control for false positives and prevent any potential misannotation. A number of statistical procedures to deal with this are in wide use in proteomics, calculating false discovery rate (FDR) and posterior error probability (PEP) values for groups and individual peptide spectrum matches (PSMs). These methods control for multiple testing and exploit decoy databases to estimate statistical significance. Here, we show that database choice has a major effect on these confidence estimates leading to significant differences in the number of PSMs reported. We note that standard target:decoy approaches using six-frame translations of nucleotide sequences, such as assembled transcriptome data, apparently underestimate the confidence assigned to the PSMs. The source of this error stems from the inflated and unusual nature of the six-frame database, where for every target sequence there exists five “incorrect” targets that are unlikely to code for protein. The attendant FDR and PEP estimates lead to fewer accepted PSMs at fixed thresholds, and we show that this effect is a product of the database and statistical modeling and not the search engine. A variety of approaches to limit database size and remove noncoding target sequences are examined and discussed in terms of the altered statistical estimates generated and PSMs reported. These results are of importance to groups carrying out proteogenomics, aiming to maximize the validation and discovery of gene structure in sequenced genomes, while still controlling for false positives. PMID:23025403

  13. Addressing Size Stereotypes: A Weight Bias and Weight-Related Teasing Intervention among Adolescents

    ERIC Educational Resources Information Center

    Miyairi, Maya; Reel, Justine J.; Próspero, Moisés; Okang, Esther N.

    2015-01-01

    Purpose: The purpose of this study was to evaluate a weight-related teasing prevention program implemented for both female and male students in a school setting. Methods: Junior High School students (N = 143) in seventh grade were invited to participate in the program. One hundred eighteen participants completed pre- and posttest surveys to assess…

  14. The shared genome is a pervasive constraint on the evolution of sex-biased gene expression.

    PubMed

    Griffin, Robert M; Dean, Rebecca; Grace, Jaime L; Rydén, Patrik; Friberg, Urban

    2013-09-01

    Males and females share most of their genomes, and differences between the sexes can therefore not evolve through sequence divergence in protein coding genes. Sexual dimorphism is instead restricted to occur through sex-specific expression and splicing of gene products. Evolution of sexual dimorphism through these mechanisms should, however, also be constrained when the sexes share the genetic architecture for regulation of gene expression. Despite these obstacles, sexual dimorphism is prevalent in the animal kingdom and commonly evolves rapidly. Here, we ask whether the genetic architecture of gene expression is plastic and easily molded by sex-specific selection, or if sexual dimorphism evolves rapidly despite pervasive genetic constraint. To address this question, we explore the relationship between the intersexual genetic correlation for gene expression (rMF), which captures how independently genes are regulated in the sexes, and the evolution of sex-biased gene expression. Using transcriptome data from Drosophila melanogaster, we find that most genes have a high rMF and that genes currently exposed to sexually antagonistic selection have a higher average rMF than other genes. We further show that genes with a high rMF have less pronounced sex-biased gene expression than genes with a low rMF within D. melanogaster and that the strength of the rMF in D. melanogaster predicts the degree to which the sex bias of a gene's expression has changed between D. melanogaster and six other species in the Drosophila genus. In sum, our results show that a shared genome constrains both short- and long-term evolution of sexual dimorphism.

  15. Diamond nucleation under bias conditions

    SciTech Connect

    Stoeckel, R.; Stammler, M.; Janischowsky, K.; Ley, L.; Albrecht, M.; Strunk, H.P.

    1998-01-01

    The so-called bias pretreatment allows the growth of heteroepitaxial diamond films by plasma chemical vapor deposition on silicon (100) surfaces. We present plan-view and cross-sectional transmission electron micrographs of the substrate surface at different phases of the bias pretreatment. These observations are augmented by measurements of the etch rates of Si, SiC, and different carbon modifications under plasma conditions and the size distribution of oriented diamond crystals grown after bias pretreatment. Based on these results a new model for diamond nucleation under bias conditions is proposed. First, a closed layer of nearly epitaxially oriented cubic SiC with a thickness of about 10 nm is formed. Subplantation of carbon into this SiC layer causes a supersaturation with carbon and results in the subcutaneous formation of epitaxially oriented nucleation centers in the SiC layer. Etching of the SiC during the bias pretreatment as well as during diamond growth brings these nucleation centers to the sample surface and causes the growth of diamonds epitaxially oriented on the Si/SiC substrate. {copyright} {ital 1998 American Institute of Physics.}

  16. A Perpendicular Biased 2nd Harmonic Cavity for the Fermilab Booster

    SciTech Connect

    Tan, C. Y.; Dey, J.; Madrak, R. L.; Pellico, W.; Romanov, G.; Sun, D.; Terechkine, I.

    2015-07-13

    A perpendicular biased 2nd harmonic cavity is currently being designed for the Fermilab Booster. Its purpose cavity is to flatten the bucket at injection and thus change the longitudinal beam distribution so that space charge effects are decreased. It can also with transition crossing. The reason for the choice of perpendicular biasing over parallel biasing is that the Q of the cavity is much higher and thus allows the accelerating voltage to be a factor of two higher than a similar parallel biased cavity. This cavity will also provide a higher accelerating voltage per meter than the present folded transmission line cavity. However, this type of cavity presents technical challenges that need to be addressed. The two major issues are cooling of the garnet material from the effects of the RF and the cavity itself from eddy current heating because of the 15 Hz bias field ramp. This paper will address the technical challenge of preventing the garnet from overheating.

  17. Integrated bias removal in passive radar systems

    NASA Astrophysics Data System (ADS)

    Subramaniam, M.; Punithakumar, K.; McDonald, M.; Kirubarajan, T.

    2008-04-01

    A passive coherent location (PCL) system exploits the ambient FM radio or television signals from powerful local transmitters, which makes it ideal for covert tracking. In a passive radar system, also known as PCL system, a variety of measurements can be used to estimate target states such as direction of arrival (DOA), time difference of arrival (TDOA) or Doppler shift. Noise and the precision of DOA estimation are main issues in a PCL system and methods such as conventional beam forming (CBF) algorithm, algebraic constant modulus algorithm (ACMA) are widely analyzed in literature to address them. In practical systems, although it is necessary to reduce the directional ambiguities, the placement of receivers closed to each other results in larger bias in the estimation of DOA of signals, especially when the targets move off bore-sight. This phenomenon leads to degradation in the performance of the tracking algorithm. In this paper, we present a method for removing the bias in DOA to alleviate the aforementioned problem. The simulation results are presented to show the effectiveness of the proposed algorithm with an example of tracking airborne targets.

  18. Can pollution bias peatland paleoclimate reconstruction?

    NASA Astrophysics Data System (ADS)

    Payne, Richard J.; Mitchell, Edward A. D.; Nguyen-Viet, Hung; Gilbert, Daniel

    2012-09-01

    Peatland testate amoebae are widely used to reconstruct paleohydrological/climatic changes, but many species are also known to respond to pollutants. Peatlands around the world have been exposed to anthropogenic and intermittent natural pollution through the late Holocene. This raises the question: can pollution lead to changes in the testate amoeba paleoecological record that could be erroneously interpreted as a climatic change? To address this issue we applied testate amoeba transfer functions to the results of experiments adding pollutants (N, P, S, Pb, O3) to peatlands and similar ecosystems. We found a significant effect in only one case, an experiment in which N and P were added, suggesting that pollution-induced biases are limited. However, we caution researchers to be aware of this possibility when interpreting paleoecological records. Studies characterising the paleoecological response to pollution allow pollution impacts to be tracked and distinguished from climate change.

  19. Conservative Tests under Satisficing Models of Publication Bias.

    PubMed

    McCrary, Justin; Christensen, Garret; Fanelli, Daniele

    2016-01-01

    Publication bias leads consumers of research to observe a selected sample of statistical estimates calculated by producers of research. We calculate critical values for statistical significance that could help to adjust after the fact for the distortions created by this selection effect, assuming that the only source of publication bias is file drawer bias. These adjusted critical values are easy to calculate and differ from unadjusted critical values by approximately 50%-rather than rejecting a null hypothesis when the t-ratio exceeds 2, the analysis suggests rejecting a null hypothesis when the t-ratio exceeds 3. Samples of published social science research indicate that on average, across research fields, approximately 30% of published t-statistics fall between the standard and adjusted cutoffs. PMID:26901834

  20. Conservative Tests under Satisficing Models of Publication Bias

    PubMed Central

    McCrary, Justin; Christensen, Garret; Fanelli, Daniele

    2016-01-01

    Publication bias leads consumers of research to observe a selected sample of statistical estimates calculated by producers of research. We calculate critical values for statistical significance that could help to adjust after the fact for the distortions created by this selection effect, assuming that the only source of publication bias is file drawer bias. These adjusted critical values are easy to calculate and differ from unadjusted critical values by approximately 50%—rather than rejecting a null hypothesis when the t-ratio exceeds 2, the analysis suggests rejecting a null hypothesis when the t-ratio exceeds 3. Samples of published social science research indicate that on average, across research fields, approximately 30% of published t-statistics fall between the standard and adjusted cutoffs. PMID:26901834

  1. Model for Codon Position Bias in RNA Editing

    NASA Astrophysics Data System (ADS)

    Liu, Tsunglin; Bundschuh, Ralf

    2005-08-01

    RNA editing can be crucial for the expression of genetic information via inserting, deleting, or substituting a few nucleotides at specific positions in an RNA sequence. Within coding regions in an RNA sequence, editing usually occurs with a certain bias in choosing the positions of the editing sites. In the mitochondrial genes of Physarum polycephalum, many more editing events have been observed at the third codon position than at the first and second, while in some plant mitochondria the second codon position dominates. Here we propose an evolutionary model that explains this bias as the basis of selection at the protein level. The model predicts a distribution of the three positions rather close to the experimental observation in Physarum. This suggests that the codon position bias in Physarum is mainly a consequence of selection at the protein level.

  2. A model for codon position bias in RNA editing

    NASA Astrophysics Data System (ADS)

    Bundschuh, Ralf; Liu, Tsunglin

    2006-03-01

    RNA editing can be crucial for the expression of genetic information via inserting, deleting, or substituting a few nucleotides at specific positions in an RNA sequence. Within coding regions in an RNA sequence, editing usually occurs with a certain bias in choosing the positions of the editing sites. In the mitochondrial genes of Physarum polycephalum, many more editing events have been observed at the third codon position than at the first and second, while in some plant mitochondria the second codon position dominates. Here we propose an evolutionary model that explains this bias as the basis of selection at the protein level. The model predicts a distribution of the three positions rather close to the experimental observation in Physarum. This suggests that the codon position bias in Physarum is mainly a consequence of selection at the protein level.

  3. Exchange bias in Fe/Cr double superlattices.

    SciTech Connect

    Jiang, J. S.; Felcher, G. P.; Inomata, A.; Goyette, R.; Nelson, C.; Bader, S. D.

    1999-11-30

    Utilizing the oscillatory interlayer exchange coupling in Fe/Cr superlattices, we have constructed ''double superlattice'' structures where a ferromagnetic (F) and an antiferromagnetic (AF) Fe/Cr superlattice are coupled through a Cr spacer. The minor hysteresis loops in the magnetization are shifted from zero field, i.e., the F superlattice is exchange biased by the AF one. The double superlattices are sputter-deposited with (211) epitaxy and possess uniaxial in-plane magnetic anisotropy. The magnitude of the bias field is satisfactorily described by the classic formula for collinear spin structures. The coherent structure and insensitivity to atomic-scale roughness makes it possible to determine the spin distribution by polarized neutron reflectivity, which confirms that the spin structure is collinear. The magnetic reversal behavior of the double superlattices suggests that a realistic model of exchange bias needs to address the process of nucleating local reverse domains.

  4. Heuristic-biased stochastic sampling

    SciTech Connect

    Bresina, J.L.

    1996-12-31

    This paper presents a search technique for scheduling problems, called Heuristic-Biased Stochastic Sampling (HBSS). The underlying assumption behind the HBSS approach is that strictly adhering to a search heuristic often does not yield the best solution and, therefore, exploration off the heuristic path can prove fruitful. Within the HBSS approach, the balance between heuristic adherence and exploration can be controlled according to the confidence one has in the heuristic. By varying this balance, encoded as a bias function, the HBSS approach encompasses a family of search algorithms of which greedy search and completely random search are extreme members. We present empirical results from an application of HBSS to the realworld problem of observation scheduling. These results show that with the proper bias function, it can be easy to outperform greedy search.

  5. Anchoring bias in online voting

    NASA Astrophysics Data System (ADS)

    Yang, Zimo; Zhang, Zi-Ke; Zhou, Tao

    2012-12-01

    Voting online with explicit ratings could largely reflect people's preferences and objects' qualities, but ratings are always irrational, because they may be affected by many unpredictable factors like mood, weather and other people's votes. By analyzing two real systems, this paper reveals a systematic bias embedding in the individual decision-making processes, namely people tend to give a low rating after a low rating, as well as a high rating following a high rating. This so-called anchoring bias is validated via extensive comparisons with null models, and numerically speaking, the extent of bias decays with voting interval in a logarithmic form. Our findings could be applied in the design of recommender systems and considered as important complementary materials to previous knowledge about anchoring effects on financial trades, performance judgments, auctions, and so on.

  6. Measurement of Receptor Signaling Bias.

    PubMed

    Kenakin, Terry

    2016-01-01

    G protein-coupled receptors (GPCRs) are often pleiotropically linked to numerous cellular signaling mechanisms in cells, and it is now known that many agonists differentially activate some signaling pathways at the expense of others. The mechanism for this effect is the stabilization of different active receptor states by different agonists, and it leads to varying qualities of efficacy for different agonists. Agonist bias is a powerful mechanism to amplify beneficial signals and diminish harmful signals, and thus improve the overall profile of agonist ligands. This unit describes a method to quantify agonist bias with a scale that enables medicinal chemists to amplify or reduce these effects in new molecules. The method is based on the Black/Leff operational model and yields a statistical estimate of the confidence for bias measurements. © 2016 by John Wiley & Sons, Inc. PMID:27636109

  7. Unpacking the Evidence of Gender Bias

    ERIC Educational Resources Information Center

    Fulmer, Connie L.

    2010-01-01

    The purpose of this study was to investigate gender bias in pre-service principals using the Gender-Leader Implicit Association Test. Analyses of student-learning narratives revealed how students made sense of gender bias (biased or not-biased) and how each reacted to evidence (surprised or not-surprised). Two implications were: (1) the need for…

  8. Measurement Bias Detection through Factor Analysis

    ERIC Educational Resources Information Center

    Barendse, M. T.; Oort, F. J.; Werner, C. S.; Ligtvoet, R.; Schermelleh-Engel, K.

    2012-01-01

    Measurement bias is defined as a violation of measurement invariance, which can be investigated through multigroup factor analysis (MGFA), by testing across-group differences in intercepts (uniform bias) and factor loadings (nonuniform bias). Restricted factor analysis (RFA) can also be used to detect measurement bias. To also enable nonuniform…

  9. A Reconsideration of Bias in the News.

    ERIC Educational Resources Information Center

    Stevenson, Robert L.; Greene, Mark T.

    This paper discusses three conceptual problems--point of view, unit of bias, and behavioral response--with using content analysis to study news bias. The paper shows that the point of view of the content analyst is not appropriate if one wants to see how news consumers define and react to bias, that the unit of bias should be the specific instance…

  10. The Truth and Bias Model of Judgment

    ERIC Educational Resources Information Center

    West, Tessa V.; Kenny, David A.

    2011-01-01

    We present a new model for the general study of how the truth and biases affect human judgment. In the truth and bias model, judgments about the world are pulled by 2 primary forces, the truth force and the bias force, and these 2 forces are interrelated. The truth and bias model differentiates force and value, where the force is the strength of…

  11. Without Bias: A Guidebook for Nondiscriminatory Communication.

    ERIC Educational Resources Information Center

    Pickens, Judy E., Ed.; And Others

    This guidebook discusses ways to eliminate various types of discrimination from business communications. Separately authored chapters discuss eliminating racial and ethnic bias; eliminating sexual bias; achieving communication sensitive about handicaps of disabled persons; eliminating bias from visual media; eliminating bias from meetings,…

  12. The Threshold of Embedded M Collider Bias and Confounding Bias

    ERIC Educational Resources Information Center

    Kelcey, Benjamin; Carlisle, Joanne

    2011-01-01

    Of particular import to this study, is collider bias originating from stratification on retreatment variables forming an embedded M or bowtie structural design. That is, rather than assume an M structural design which suggests that "X" is a collider but not a confounder, the authors adopt what they consider to be a more reasonable position and…

  13. Solar array/spacecraft biasing

    NASA Technical Reports Server (NTRS)

    Fitzgerald, D. J.

    1981-01-01

    Biasing techniques and their application to the control of spacecraft potential is discussed. Normally when a spacecraft is operated with ion thrusters, the spacecraft will be 10-20 volts negative of the surrounding plasma. This will affect scientific measurements and will allow ions from the charge-exchange plasma to bombard the spacecraft surfaces with a few tens of volts of energy. This condition may not be tolerable. A proper bias system is described that can bring the spacecraft to or near the potential of the surrounding plasma.

  14. Student Perceptions of Peer Credibility Based on Email Addresses

    ERIC Educational Resources Information Center

    Livermore, Jeffrey A.; Scafe, Marla G.; Wiechowski, Linda S.; Maier, David J.

    2013-01-01

    The purpose of this study was to evaluate students' perceptions of their peer's credibility based on email addresses. The survey was conducted at a community college in Michigan where all students were registered and actively taking at least one course. The survey results show that a student's selection of an email address does influence other…

  15. Faculty Perceptions of Student Credibility Based on Email Addresses

    ERIC Educational Resources Information Center

    Livermore, Jeffrey A.; Wiechowski, Linda S.; Scafe, Marla G.

    2011-01-01

    The purpose of this study was to evaluate faculty perceptions of student credibility based on email addresses. The survey was conducted at an upper division business school in Michigan where all students have completed at least two years of college courses. The survey results show that a student's selection of an email address does influence the…

  16. Student Perceptions of Faculty Credibility Based on Email Addresses

    ERIC Educational Resources Information Center

    Livermore, Jeffrey A.; Scafe, Marla G.; Wiechowski, Linda S.

    2010-01-01

    The purpose of this study was to evaluate students' perceptions of faculty credibility based on email addresses. The survey was conducted at an upper division business school in Michigan where all students have completed at least two years of college courses. The survey results show that a faculty member's selection of an email address does…

  17. Addressing problems of employee performance.

    PubMed

    McConnell, Charles R

    2011-01-01

    Employee performance problems are essentially of 2 kinds: those that are motivational in origin and those resulting from skill deficiencies. Both kinds of problems are the province of the department manager. Performance problems differ from problems of conduct in that traditional disciplinary processes ordinarily do not apply. Rather, performance problems are addressed through educational and remedial processes. The manager has a basic responsibility in ensuring that everything reasonable is done to help each employee succeed. There are a number of steps the manager can take to address employee performance problems.

  18. Does suggestive information cause a confirmation bias in bullet comparisons?

    PubMed

    Kerstholt, Jose; Eikelboom, Aletta; Dijkman, Tjisse; Stoel, Reinoud; Hermsen, Rob; van Leuven, Bert

    2010-05-20

    Several researchers have argued that the confirmation bias, the tendency to selectively gather and process information such that it fits existing beliefs, is a main threat to objective forensic examinations. The goal of the present study was to empirically investigate whether examiners making bullet comparisons are indeed vulnerable to this bias. In the first experiment, six qualified examiners evaluated 6 sets of bullets that were presented to them twice. In the neutral task condition it was mentioned in the case description that there were two perpetrators and two crime scenes, whereas in the potentially biasing task condition it was mentioned that there was only one perpetrator and one crime scene. The results showed no effect of biased information on the decision outcome. An exploratory analysis revealed rather large individual differences in two cases. In a second study we compared the conclusions of first and second examiners of actual cases that were conducted in the period between 1997 and 2006. As the second examiner mostly has no context information it may be expected that the conclusion of the first examiner should be more extreme when he or she would have become prey to a confirmation bias. The results indicate an effect in the opposite direction: the first examiner gave less extreme ratings than the second one. In all, our results indicate that examiners were not affected by biased information the case description.

  19. Bias in Dynamic Monte Carlo Alpha Calculations

    SciTech Connect

    Sweezy, Jeremy Ed; Nolen, Steven Douglas; Adams, Terry R.; Trahan, Travis John

    2015-02-06

    A 1/N bias in the estimate of the neutron time-constant (commonly denoted as α) has been seen in dynamic neutronic calculations performed with MCATK. In this paper we show that the bias is most likely caused by taking the logarithm of a stochastic quantity. We also investigate the known bias due to the particle population control method used in MCATK. We conclude that this bias due to the particle population control method is negligible compared to other sources of bias.

  20. Examinations of Home Economics Textbooks for Sex Bias.

    ERIC Educational Resources Information Center

    Weis, Susan F.

    1979-01-01

    Four analyses were conducted on a sample of 100 randomly selected, secondary home economics textbooks published between 1964 and 1974. Results indicated that the contents presented sex bias in language usage, in pictures portraying male and female role environments, and in role behaviors and expectations emphasized. (Author/JH)

  1. Advisory List of Instructional Media for Reduction of Sex Bias.

    ERIC Educational Resources Information Center

    North Carolina State Dept. of Public Instruction, Raleigh. Div. of Educational Media.

    Instructional media appropriate to schools' efforts to reduce sex bias are described in this advisory list. Entries were selected from those materials submitted by publishers which received favorable reviews by educators. Most materials were evaluated by members of the Raleigh, North Carolina chapter of the National Organization for Women.…

  2. A Simulation Platform for Quantifying Survival Bias: An Application to Research on Determinants of Cognitive Decline.

    PubMed

    Mayeda, Elizabeth Rose; Tchetgen Tchetgen, Eric J; Power, Melinda C; Weuve, Jennifer; Jacqmin-Gadda, Hélène; Marden, Jessica R; Vittinghoff, Eric; Keiding, Niels; Glymour, M Maria

    2016-09-01

    Bias due to selective mortality is a potential concern in many studies and is especially relevant in cognitive aging research because cognitive impairment strongly predicts subsequent mortality. Biased estimation of the effect of an exposure on rate of cognitive decline can occur when mortality is a common effect of exposure and an unmeasured determinant of cognitive decline and in similar settings. This potential is often represented as collider-stratification bias in directed acyclic graphs, but it is difficult to anticipate the magnitude of bias. In this paper, we present a flexible simulation platform with which to quantify the expected bias in longitudinal studies of determinants of cognitive decline. We evaluated potential survival bias in naive analyses under several selective survival scenarios, assuming that exposure had no effect on cognitive decline for anyone in the population. Compared with the situation with no collider bias, the magnitude of bias was higher when exposure and an unmeasured determinant of cognitive decline interacted on the hazard ratio scale to influence mortality or when both exposure and rate of cognitive decline influenced mortality. Bias was, as expected, larger in high-mortality situations. This simulation platform provides a flexible tool for evaluating biases in studies with high mortality, as is common in cognitive aging research. PMID:27578690

  3. Attentional bias towards threatening stimuli in children with anxiety: A meta-analysis.

    PubMed

    Dudeney, Joanne; Sharpe, Louise; Hunt, Caroline

    2015-08-01

    Although it is well known that anxious adults show selective attention to threatening stimuli, research investigating attentional bias in children with anxiety has produced mixed results. The purpose of this paper is to provide a comprehensive analysis of studies investigating attentional bias in children with anxiety. Using a systematic search for articles which included both children with anxiety and reported data suitable for a meta-analysis, 38 articles were identified involving 4221 subjects (anxiety n=2222). We used a random effects meta-analysis with standardized mean difference as our primary outcome to estimate between- and within-group effects of attentional bias towards threat-related information in children with anxiety. Overall, children with anxiety showed a significantly greater bias to threat-related stimuli, compared to controls (d=0.21). Children with anxiety also showed a significant bias to threat-related stimuli, over neutral stimuli (d=0.54), which was greater than the bias shown by control children (d=0.15). Specific variables in attentional bias were also explored, with varying results. The review concluded that anxious children do show a similar bias towards threatening stimuli as has been documented in adults, albeit to a lesser degree and this bias is moderated by age, such that the difference between anxious and control children increases with age. Given the small number of studies in some areas, future research is needed to understand the precise conditions under which anxious children exhibit selective attentional biases to threat-related stimuli.

  4. Selective Prevention: Addressing Vulnerability to Problem Drug Use in Europe

    ERIC Educational Resources Information Center

    Burkhart, Gregor; Gyarmathy, V. Anna; Bo, Alessandra

    2011-01-01

    Following the 2003 publication of the European Union (EU) Council Recommendations and the 2005-2008 and 2009-2012 EU Drugs Action Plans, increasing attention has been given in EU member states' drug policies to populations that are vulnerable to problem drug use (PDU). Monitoring data reported to the EMCDDA by designated agencies from 30 countries…

  5. Addressing Phonological Questions with Ultrasound

    ERIC Educational Resources Information Center

    Davidson, Lisa

    2005-01-01

    Ultrasound can be used to address unresolved questions in phonological theory. To date, some studies have shown that results from ultrasound imaging can shed light on how differences in phonological elements are implemented. Phenomena that have been investigated include transitional schwa, vowel coalescence, and transparent vowels. A study of…

  6. Every Other Day. Keynote Address.

    ERIC Educational Resources Information Center

    Tiller, Tom

    Schools need to be reoriented and restructured so that what is taught and learned, and the way in which it is taught and learned, are better integrated with young people's real-world experiences. Many indicators suggest that the meaningful aspects of school have been lost in the encounter with modern times. The title of this address--"Every Other…

  7. State of the Lab Address

    SciTech Connect

    King, Alex

    2010-01-01

    In his third-annual State of the Lab address, Ames Laboratory Director Alex King called the past year one of "quiet but strong progress" and called for Ames Laboratory to continue to build on its strengths while responding to changing expectations for energy research.

  8. State of the Lab Address

    ScienceCinema

    King, Alex

    2016-07-12

    In his third-annual State of the Lab address, Ames Laboratory Director Alex King called the past year one of "quiet but strong progress" and called for Ames Laboratory to continue to build on its strengths while responding to changing expectations for energy research.

  9. Quality of evidence revealing subtle gender biases in science is in the eye of the beholder

    PubMed Central

    Handley, Ian M.; Brown, Elizabeth R.; Moss-Racusin, Corinne A.; Smith, Jessi L.

    2015-01-01

    Scientists are trained to evaluate and interpret evidence without bias or subjectivity. Thus, growing evidence revealing a gender bias against women—or favoring men—within science, technology, engineering, and mathematics (STEM) settings is provocative and raises questions about the extent to which gender bias may contribute to women’s underrepresentation within STEM fields. To the extent that research illustrating gender bias in STEM is viewed as convincing, the culture of science can begin to address the bias. However, are men and women equally receptive to this type of experimental evidence? This question was tested with three randomized, double-blind experiments—two involving samples from the general public (n = 205 and 303, respectively) and one involving a sample of university STEM and non-STEM faculty (n = 205). In all experiments, participants read an actual journal abstract reporting gender bias in a STEM context (or an altered abstract reporting no gender bias in experiment 3) and evaluated the overall quality of the research. Results across experiments showed that men evaluate the gender-bias research less favorably than women, and, of concern, this gender difference was especially prominent among STEM faculty (experiment 2). These results suggest a relative reluctance among men, especially faculty men within STEM, to accept evidence of gender biases in STEM. This finding is problematic because broadening the participation of underrepresented people in STEM, including women, necessarily requires a widespread willingness (particularly by those in the majority) to acknowledge that bias exists before transformation is possible. PMID:26460001

  10. Quality of evidence revealing subtle gender biases in science is in the eye of the beholder.

    PubMed

    Handley, Ian M; Brown, Elizabeth R; Moss-Racusin, Corinne A; Smith, Jessi L

    2015-10-27

    Scientists are trained to evaluate and interpret evidence without bias or subjectivity. Thus, growing evidence revealing a gender bias against women-or favoring men-within science, technology, engineering, and mathematics (STEM) settings is provocative and raises questions about the extent to which gender bias may contribute to women's underrepresentation within STEM fields. To the extent that research illustrating gender bias in STEM is viewed as convincing, the culture of science can begin to address the bias. However, are men and women equally receptive to this type of experimental evidence? This question was tested with three randomized, double-blind experiments-two involving samples from the general public (n = 205 and 303, respectively) and one involving a sample of university STEM and non-STEM faculty (n = 205). In all experiments, participants read an actual journal abstract reporting gender bias in a STEM context (or an altered abstract reporting no gender bias in experiment 3) and evaluated the overall quality of the research. Results across experiments showed that men evaluate the gender-bias research less favorably than women, and, of concern, this gender difference was especially prominent among STEM faculty (experiment 2). These results suggest a relative reluctance among men, especially faculty men within STEM, to accept evidence of gender biases in STEM. This finding is problematic because broadening the participation of underrepresented people in STEM, including women, necessarily requires a widespread willingness (particularly by those in the majority) to acknowledge that bias exists before transformation is possible. PMID:26460001

  11. Quality of evidence revealing subtle gender biases in science is in the eye of the beholder.

    PubMed

    Handley, Ian M; Brown, Elizabeth R; Moss-Racusin, Corinne A; Smith, Jessi L

    2015-10-27

    Scientists are trained to evaluate and interpret evidence without bias or subjectivity. Thus, growing evidence revealing a gender bias against women-or favoring men-within science, technology, engineering, and mathematics (STEM) settings is provocative and raises questions about the extent to which gender bias may contribute to women's underrepresentation within STEM fields. To the extent that research illustrating gender bias in STEM is viewed as convincing, the culture of science can begin to address the bias. However, are men and women equally receptive to this type of experimental evidence? This question was tested with three randomized, double-blind experiments-two involving samples from the general public (n = 205 and 303, respectively) and one involving a sample of university STEM and non-STEM faculty (n = 205). In all experiments, participants read an actual journal abstract reporting gender bias in a STEM context (or an altered abstract reporting no gender bias in experiment 3) and evaluated the overall quality of the research. Results across experiments showed that men evaluate the gender-bias research less favorably than women, and, of concern, this gender difference was especially prominent among STEM faculty (experiment 2). These results suggest a relative reluctance among men, especially faculty men within STEM, to accept evidence of gender biases in STEM. This finding is problematic because broadening the participation of underrepresented people in STEM, including women, necessarily requires a widespread willingness (particularly by those in the majority) to acknowledge that bias exists before transformation is possible.

  12. Assessment of bias correction under transient climate change

    NASA Astrophysics Data System (ADS)

    Van Schaeybroeck, Bert; Vannitsem, Stéphane

    2015-04-01

    Calibration of climate simulations is necessary since large systematic discrepancies are generally found between the model climate and the observed climate. Recent studies have cast doubt upon the common assumption of the bias being stationary when the climate changes. This led to the development of new methods, mostly based on linear sensitivity of the biases as a function of time or forcing (Kharin et al. 2012). However, recent studies uncovered more fundamental problems using both low-order systems (Vannitsem 2011) and climate models, showing that the biases may display complicated non-linear variations under climate change. This last analysis focused on biases derived from the equilibrium climate sensitivity, thereby ignoring the effect of the transient climate sensitivity. Based on the linear response theory, a general method of bias correction is therefore proposed that can be applied on any climate forcing scenario. The validity of the method is addressed using twin experiments with a climate model of intermediate complexity LOVECLIM (Goosse et al., 2010). We evaluate to what extent the bias change is sensitive to the structure (frequency) of the applied forcing (here greenhouse gases) and whether the linear response theory is valid for global and/or local variables. To answer these question we perform large-ensemble simulations using different 300-year scenarios of forced carbon-dioxide concentrations. Reality and simulations are assumed to differ by a model error emulated as a parametric error in the wind drag or in the radiative scheme. References [1] H. Goosse et al., 2010: Description of the Earth system model of intermediate complexity LOVECLIM version 1.2, Geosci. Model Dev., 3, 603-633. [2] S. Vannitsem, 2011: Bias correction and post-processing under climate change, Nonlin. Processes Geophys., 18, 911-924. [3] V.V. Kharin, G. J. Boer, W. J. Merryfield, J. F. Scinocca, and W.-S. Lee, 2012: Statistical adjustment of decadal predictions in a changing

  13. Measurement bias in activation-recovery intervals from unipolar electrograms

    PubMed Central

    Hanson, Ben; Taggart, Peter

    2014-01-01

    The activation-recovery interval (ARI) calculated from unipolar electrograms is regularly used as a convenient surrogate measure of local cardiac action potential durations (APD). This method enables important research bridging between computational studies and in vitro and in vivo human studies. The Wyatt method is well established as a theoretically sound method for calculating ARIs; however, some studies have observed that it is prone to a bias error in measurement when applied to positive T waves. This article demonstrates that recent theoretical and computational studies supporting the use of the Wyatt method are likely to have underestimated the extent of this bias in many practical experimental recording scenarios. This work addresses these situations and explains the measurement bias by adapting existing theoretical expressions of the electrogram to represent practical experimental recording configurations. A new analytic expression for the electrogram's local component is derived, which identifies the source of measurement bias for positive T waves. A computer implementation of the new analytic model confirms our hypothesis that the bias is systematically dependent on the electrode configuration. These results provide an aid to electrogram interpretation in general, and this work's outcomes are used to make recommendations on how to minimize measurement error. PMID:25398981

  14. Attributional Bias and Course Evaluations.

    ERIC Educational Resources Information Center

    Gigliotti, Richard J.; Buchtel, Foster S.

    1990-01-01

    How self-serving bias affects evaluations of college courses was tested for 691 students by comparing a model predicting that evaluations reflect actual grades with a model predicting that evaluations reflect confirmation or disconfirmation of expectations. Results support course evaluation validity by indicating a minimal effect of self-serving…

  15. Combating Anti-Muslim Bias

    ERIC Educational Resources Information Center

    Shah, Nirvi

    2011-01-01

    America's 2.5 million Muslims make up less than 1% of the U.S. population, according to the Pew Research Center. Many Muslim students face discrimination and some cases have warranted investigation by the U.S. Department of Education's Office of Civil Rights. Muslim groups have reported widespread bias as well. For many Muslim…

  16. Stereotype Formation: Biased by Association

    ERIC Educational Resources Information Center

    Le Pelley, Mike E.; Reimers, Stian J.; Calvini, Guglielmo; Spears, Russell; Beesley, Tom; Murphy, Robin A.

    2010-01-01

    We propose that biases in attitude and stereotype formation might arise as a result of learned differences in the extent to which social groups have previously been predictive of behavioral or physical properties. Experiments 1 and 2 demonstrate that differences in the experienced predictiveness of groups with respect to evaluatively neutral…

  17. Key Words in Instruction. Bias

    ERIC Educational Resources Information Center

    Callison, Daniel

    2005-01-01

    Two challenging criteria for judging information involve bias and authority. In both cases, judgments may not be clearly possible. In both cases, there may be degrees or levels of acceptability. For students to gain experience and to demonstrate skills in making judgments, they need opportunities to consider a wide spectrum of resources under a…

  18. Bias correction method for climate change impact assessment at a basin scale

    NASA Astrophysics Data System (ADS)

    Nyunt, C.; Jaranilla-sanchez, P. A.; Yamamoto, A.; Nemoto, T.; Kitsuregawa, M.; Koike, T.

    2012-12-01

    . In this study, the lowest value of AMS of observed is selected as threshold and simultaneously same frequency is considered as extremes in corresponding GCM gridded series. After fitting to GP distribution, bias corrected GCM extreme is found by using the inverse function of observed extremes. The results show it can remove bias effectively. For projected climate, the same transfer function between historical observed and GCM was applied. Moreover, frequency analysis of maximum extreme intensity estimation was done for validation and then approximate for near future by using identical function as past. To fix the error in the number of no rain days of GCM, ranking order statistics is used and define in GCM same as the frequency of wet days in observed station. After this rank, GCM output will be zero and identify same threshold for future projection. Normal rainfall is classified as between threshold of extreme and no rain day. We assume monthly normal rainfall follow gamma distribution. Then, we mapped the CDF of GCM normal rainfall to station's one in each month and bias corrected rainfall is available. In summary, bias of GCM have been addressed efficiently and validated at point scale by seasonal climatology and at all stations for evaluating downscaled rainfall performance. The results show bias corrected and downscaled scheme is good enough for climate impact study.

  19. Biased Signaling of Protease-Activated Receptors

    PubMed Central

    Zhao, Peishen; Metcalf, Matthew; Bunnett, Nigel W.

    2014-01-01

    In addition to their role in protein degradation and digestion, proteases can also function as hormone-like signaling molecules that regulate vital patho-physiological processes, including inflammation, hemostasis, pain, and repair mechanisms. Certain proteases can signal to cells by cleaving protease-activated receptors (PARs), a family of four G protein-coupled receptors. PARs are expressed by almost all cell types, control important physiological and disease-relevant processes, and are an emerging therapeutic target for major diseases. Most information about PAR activation and function derives from studies of a few proteases, for example thrombin in the case of PAR1, PAR3, and PAR4, and trypsin in the case of PAR2 and PAR4. These proteases cleave PARs at established sites with the extracellular N-terminal domains, and expose tethered ligands that stabilize conformations of the cleaved receptors that activate the canonical pathways of G protein- and/or β-arrestin-dependent signaling. However, a growing number of proteases have been identified that cleave PARs at divergent sites to activate distinct patterns of receptor signaling and trafficking. The capacity of these proteases to trigger distinct signaling pathways is referred to as biased signaling, and can lead to unique patho-physiological outcomes. Given that a different repertoire of proteases are activated in various patho-physiological conditions that may activate PARs by different mechanisms, signaling bias may account for the divergent actions of proteases and PARs. Moreover, therapies that target disease-relevant biased signaling pathways may be more effective and selective approaches for the treatment of protease- and PAR-driven diseases. Thus, rather than mediating the actions of a few proteases, PARs may integrate the biological actions of a wide spectrum of proteases in different patho-physiological conditions. PMID:24860547

  20. Improved analysis of bias in Monte Carlo criticality safety

    NASA Astrophysics Data System (ADS)

    Haley, Thomas C.

    2000-08-01

    model is demonstrated. Simulations of the bias model development by a casual analyst are compared with the rigorously developed bias model. In particular, questions of benchmark critical experiment sample size and selection methods are examined.

  1. Biased Brownian dynamics for rate constant calculation.

    PubMed

    Zou, G; Skeel, R D; Subramaniam, S

    2000-08-01

    An enhanced sampling method-biased Brownian dynamics-is developed for the calculation of diffusion-limited biomolecular association reaction rates with high energy or entropy barriers. Biased Brownian dynamics introduces a biasing force in addition to the electrostatic force between the reactants, and it associates a probability weight with each trajectory. A simulation loses weight when movement is along the biasing force and gains weight when movement is against the biasing force. The sampling of trajectories is then biased, but the sampling is unbiased when the trajectory outcomes are multiplied by their weights. With a suitable choice of the biasing force, more reacted trajectories are sampled. As a consequence, the variance of the estimate is reduced. In our test case, biased Brownian dynamics gives a sevenfold improvement in central processing unit (CPU) time with the choice of a simple centripetal biasing force.

  2. Biased Brownian dynamics for rate constant calculation.

    PubMed

    Zou, G; Skeel, R D; Subramaniam, S

    2000-08-01

    An enhanced sampling method-biased Brownian dynamics-is developed for the calculation of diffusion-limited biomolecular association reaction rates with high energy or entropy barriers. Biased Brownian dynamics introduces a biasing force in addition to the electrostatic force between the reactants, and it associates a probability weight with each trajectory. A simulation loses weight when movement is along the biasing force and gains weight when movement is against the biasing force. The sampling of trajectories is then biased, but the sampling is unbiased when the trajectory outcomes are multiplied by their weights. With a suitable choice of the biasing force, more reacted trajectories are sampled. As a consequence, the variance of the estimate is reduced. In our test case, biased Brownian dynamics gives a sevenfold improvement in central processing unit (CPU) time with the choice of a simple centripetal biasing force. PMID:10919998

  3. Manufacturing an advanced process characterization reticle incorporating halftone biasing

    NASA Astrophysics Data System (ADS)

    Nakagawa, Kent H.; Van Den Broeke, Douglas J.; Chen, J. Fung; Laidig, Thomas L.; Wampler, Kurt E.; Caldwell, Roger F.

    1999-04-01

    As the semiconductor roadmap continues to require imaging of smaller feature son wafers, we continue to explore new approaches in OPC strategies to extend the lifespan of existing technology. In this paper, we study a new OPC technology, called halftone biasing, and its application on an OPC characterization reticle, designed by MicroUnity Systems Engineering, Inc. The RTP9 test reticle is the latest in a series of 'LineSweeper' characterization reticles. Each reticle contains a wide range of line width sand pitches, each with several alternative OPC treatments, including references cases, scattering bars, and fine biasing. One of RTP9's design requirements was to support very fine, incremental biases for densely-pitched lines. Ordinarily, this would dictate a reduced address unit and with it the costly penalty of a square-law increase in e- beam write time. RTP9 incorporates a new OPC strategy, called halftone biasing, which has been proposed to address this problem. Taking advantage of optical reduction printing, this technique applies a sub-resolution halftone screen to the edges of figures to accomplish fine biasing equivalent to using an address unit one-fourth of the size of the actual e-beam writing grid. The resulting edge structure has some of the characteristics of aggressive OPC structures, but can be used in areas where traditional scattering bars cannot be placed. The trade-off between the faster write times achieved and the inflation of pattern file size is examined. The manufacturability and inspectability of halftone-biased lines on the RTP9 test reticle are explored. Pattern fidelity is examined using both optical and SEM tools. Printed 0.18 micrometers DUV resist line edge profiles are compared for both halftone and non- halftone feature edges. The CD uniformity of the OPC features, and result of die-to-database inspection are reported. The application of halftone biasing to real circuits, including the impact of data volume and saved write time

  4. Causal Inference and Omitted Variable Bias in Financial Aid Research: Assessing Solutions

    ERIC Educational Resources Information Center

    Riegg, Stephanie K.

    2008-01-01

    This article highlights the problem of omitted variable bias in research on the causal effect of financial aid on college-going. I first describe the problem of self-selection and the resulting bias from omitted variables. I then assess and explore the strengths and weaknesses of random assignment, multivariate regression, proxy variables, fixed…

  5. Examining Readers' Evaluations of Objectivity and Bias in News Discourse

    ERIC Educational Resources Information Center

    Cramer, Peter; Eisenhart, Christopher

    2014-01-01

    Readers' objectivity and bias evaluations of news texts were investigated in order to better understand the process by which readers make these kinds of judgments and the evidence on which they base them. Readers were primed to evaluate news texts for objectivity and bias, and their selections and metacommentary were analyzed. Readers…

  6. Trial Registration: Understanding and Preventing Reporting Bias in Social Work Research

    ERIC Educational Resources Information Center

    Harrison, Bronwyn A.; Mayo-Wilson, Evan

    2014-01-01

    Randomized controlled trials are considered the gold standard for evaluating social work interventions. However, published reports can systematically overestimate intervention effects when researchers selectively report large and significant findings. Publication bias and other types of reporting biases can be minimized through prospective trial…

  7. Elimination of Position-Biased Responding in Individuals with Autism and Intellectual Disabilities

    ERIC Educational Resources Information Center

    Bourret, Jason C.; Iwata, Brian A.; Harper, Jill M.; North, Stephen T.

    2012-01-01

    Five individuals with autism or other developmental disabilities participated in paired-stimulus preference assessments during repeated baseline probes. All subjects initially showed a pronounced bias by typically selecting the stimulus placed in either the left or right position. Biased responding for 3 subjects was eliminated when training…

  8. Declining Bias and Gender Wage Discrimination? A Meta-Regression Analysis

    ERIC Educational Resources Information Center

    Jarrell, Stephen B.; Stanley, T. D.

    2004-01-01

    The meta-regression analysis reveals that there is a strong tendency for discrimination estimates to fall and wage discrimination exist against the woman. The biasing effect of researchers' gender of not correcting for selection bias has weakened and changes in labor market have made it less important.

  9. An Evaluation of Some Models for Test Bias. Technical Bulletin No. 23.

    ERIC Educational Resources Information Center

    Petersen, Nancy S.; Novick, Melvin R.

    Models proposed by Cleary, Thorndike, Cole, Einhorn and Bass, and Darlington for analyzing bias in the use of tests in a selection strategy are surveyed. Six additional models for test bias are also introduced. The purpose is to describe, compare, contrast, and evaluate these models while, at the same time, extracting such useful ideas as may be…

  10. Biasing and fast degaussing circuit for magnetic materials

    DOEpatents

    Dress, Jr., William B.; McNeilly, David R.

    1984-01-01

    A dual-function circuit is provided which may be used to both magnetically bias and alternately, quickly degauss a magnetic device. The circuit may be magnetically coupled or directly connected electrically to a magnetic device, such as a magnetostrictive transducer, to magnetically bias the device by applying a d.c. current and alternately apply a selectively damped a.c. current to the device to degauss the device. The circuit is of particular value in many systems which use magnetostrictive transducers for ultrasonic transmission in different propagation modes over very short time periods.

  11. Biasing and fast degaussing circuit for magnetic materials

    DOEpatents

    Dress, W.B. Jr.; McNeilly, D.R.

    1983-10-04

    A dual-function circuit is provided which may be used to both magnetically bias and alternately, quickly degauss a magnetic device. The circuit may be magnetically coupled or directly connected electrically to a magnetic device, such as a magnetostrictive transducer, to magnetically bias the device by applying a dc current and alternately apply a selectively damped ac current to the device to degauss the device. The circuit is of particular value in many systems which use magnetostrictive transducers for ultrasonic transmission in different propagation modes over very short time periods.

  12. Can decision biases improve insurance outcomes? An experiment on status quo bias in health insurance choice.

    PubMed

    Krieger, Miriam; Felder, Stefan

    2013-06-01

    Rather than conforming to the assumption of perfect rationality in neoclassical economic theory, decision behavior has been shown to display a host of systematic biases. Properly understood, these patterns can be instrumentalized to improve outcomes in the public realm. We conducted a laboratory experiment to study whether decisions over health insurance policies are subject to status quo bias and, if so, whether experience mitigates this framing effect. Choices in two treatment groups with status quo defaults are compared to choices in a neutrally framed control group. A two-step design features sorting of subjects into the groups, allowing us to control for selection effects due to risk preferences. The results confirm the presence of a status quo bias in consumer choices over health insurance policies. However, this effect of the default framing does not persist as subjects repeat this decision in later periods of the experiment. Our results have implications for health care policy, for example suggesting that the use of non-binding defaults in health insurance can facilitate the spread of co-insurance policies and thereby help contain health care expenditure. PMID:23783222

  13. Can decision biases improve insurance outcomes? An experiment on status quo bias in health insurance choice.

    PubMed

    Krieger, Miriam; Felder, Stefan

    2013-06-19

    Rather than conforming to the assumption of perfect rationality in neoclassical economic theory, decision behavior has been shown to display a host of systematic biases. Properly understood, these patterns can be instrumentalized to improve outcomes in the public realm. We conducted a laboratory experiment to study whether decisions over health insurance policies are subject to status quo bias and, if so, whether experience mitigates this framing effect. Choices in two treatment groups with status quo defaults are compared to choices in a neutrally framed control group. A two-step design features sorting of subjects into the groups, allowing us to control for selection effects due to risk preferences. The results confirm the presence of a status quo bias in consumer choices over health insurance policies. However, this effect of the default framing does not persist as subjects repeat this decision in later periods of the experiment. Our results have implications for health care policy, for example suggesting that the use of non-binding defaults in health insurance can facilitate the spread of co-insurance policies and thereby help contain health care expenditure.

  14. Can Decision Biases Improve Insurance Outcomes? An Experiment on Status Quo Bias in Health Insurance Choice

    PubMed Central

    Krieger, Miriam; Felder, Stefan

    2013-01-01

    Rather than conforming to the assumption of perfect rationality in neoclassical economic theory, decision behavior has been shown to display a host of systematic biases. Properly understood, these patterns can be instrumentalized to improve outcomes in the public realm. We conducted a laboratory experiment to study whether decisions over health insurance policies are subject to status quo bias and, if so, whether experience mitigates this framing effect. Choices in two treatment groups with status quo defaults are compared to choices in a neutrally framed control group. A two-step design features sorting of subjects into the groups, allowing us to control for selection effects due to risk preferences. The results confirm the presence of a status quo bias in consumer choices over health insurance policies. However, this effect of the default framing does not persist as subjects repeat this decision in later periods of the experiment. Our results have implications for health care policy, for example suggesting that the use of non-binding defaults in health insurance can facilitate the spread of co-insurance policies and thereby help contain health care expenditure. PMID:23783222

  15. Proactive inhibitory control: A general biasing account☆

    PubMed Central

    Elchlepp, Heike; Lavric, Aureliu; Chambers, Christopher D.; Verbruggen, Frederick

    2016-01-01

    Flexible behavior requires a control system that can inhibit actions in response to changes in the environment. Recent studies suggest that people proactively adjust response parameters in anticipation of a stop signal. In three experiments, we tested the hypothesis that proactive inhibitory control involves adjusting both attentional and response settings, and we explored the relationship with other forms of proactive and anticipatory control. Subjects responded to the color of a stimulus. On some trials, an extra signal occurred. The response to this signal depended on the task context subjects were in: in the ‘ignore’ context, they ignored it; in the ‘stop’ context, they had to withhold their response; and in the ‘double-response’ context, they had to execute a secondary response. An analysis of event-related brain potentials for no-signal trials in the stop context revealed that proactive inhibitory control works by biasing the settings of lower-level systems that are involved in stimulus detection, action selection, and action execution. Furthermore, subjects made similar adjustments in the double-response and stop-signal contexts, indicating an overlap between various forms of proactive action control. The results of Experiment 1 also suggest an overlap between proactive inhibitory control and preparatory control in task-switching studies: both require reconfiguration of task-set parameters to bias or alter subordinate processes. We conclude that much of the top-down control in response inhibition tasks takes place before the inhibition signal is presented. PMID:26859519

  16. Bayesian ROC curve estimation under verification bias.

    PubMed

    Gu, Jiezhun; Ghosal, Subhashis; Kleiner, David E

    2014-12-20

    Receiver operating characteristic (ROC) curve has been widely used in medical science for its ability to measure the accuracy of diagnostic tests under the gold standard. However, in a complicated medical practice, a gold standard test can be invasive, expensive, and its result may not always be available for all the subjects under study. Thus, a gold standard test is implemented only when it is necessary and possible. This leads to the so-called 'verification bias', meaning that subjects with verified disease status (also called label) are not selected in a completely random fashion. In this paper, we propose a new Bayesian approach for estimating an ROC curve based on continuous data following the popular semiparametric binormal model in the presence of verification bias. By using a rank-based likelihood, and following Gibbs sampling techniques, we compute the posterior distribution of the binormal parameters intercept and slope, as well as the area under the curve by imputing the missing labels within Markov Chain Monte-Carlo iterations. Consistency of the resulting posterior under mild conditions is also established. We compare the new method with other comparable methods and conclude that our estimator performs well in terms of accuracy. PMID:25269427

  17. Proactive inhibitory control: A general biasing account.

    PubMed

    Elchlepp, Heike; Lavric, Aureliu; Chambers, Christopher D; Verbruggen, Frederick

    2016-05-01

    Flexible behavior requires a control system that can inhibit actions in response to changes in the environment. Recent studies suggest that people proactively adjust response parameters in anticipation of a stop signal. In three experiments, we tested the hypothesis that proactive inhibitory control involves adjusting both attentional and response settings, and we explored the relationship with other forms of proactive and anticipatory control. Subjects responded to the color of a stimulus. On some trials, an extra signal occurred. The response to this signal depended on the task context subjects were in: in the 'ignore' context, they ignored it; in the 'stop' context, they had to withhold their response; and in the 'double-response' context, they had to execute a secondary response. An analysis of event-related brain potentials for no-signal trials in the stop context revealed that proactive inhibitory control works by biasing the settings of lower-level systems that are involved in stimulus detection, action selection, and action execution. Furthermore, subjects made similar adjustments in the double-response and stop-signal contexts, indicating an overlap between various forms of proactive action control. The results of Experiment 1 also suggest an overlap between proactive inhibitory control and preparatory control in task-switching studies: both require reconfiguration of task-set parameters to bias or alter subordinate processes. We conclude that much of the top-down control in response inhibition tasks takes place before the inhibition signal is presented. PMID:26859519

  18. Variable-bias coin tossing

    NASA Astrophysics Data System (ADS)

    Colbeck, Roger; Kent, Adrian

    2006-03-01

    Alice is a charismatic quantum cryptographer who believes her parties are unmissable; Bob is a (relatively) glamorous string theorist who believes he is an indispensable guest. To prevent possibly traumatic collisions of self-perception and reality, their social code requires that decisions about invitation or acceptance be made via a cryptographically secure variable-bias coin toss (VBCT). This generates a shared random bit by the toss of a coin whose bias is secretly chosen, within a stipulated range, by one of the parties; the other party learns only the random bit. Thus one party can secretly influence the outcome, while both can save face by blaming any negative decisions on bad luck. We describe here some cryptographic VBCT protocols whose security is guaranteed by quantum theory and the impossibility of superluminal signaling, setting our results in the context of a general discussion of secure two-party computation. We also briefly discuss other cryptographic applications of VBCT.

  19. Belief bias and relational reasoning.

    PubMed

    Roberts, Maxwell J; Sykes, Elizabeth D A

    2003-01-01

    When people evaluate categorical syllogisms, they tend to reject unbelievable conclusions and accept believable ones irrespective of their validity. Typically, this effect is particularly marked for invalid conclusions that are possible, but do not necessarily follow, given the premises. However, smaller believability effects can also be detected for other types of conclusion. Three experiments are reported here, in which an attempt was made to determine whether belief bias effects can manifest themselves on the relational inference task. Subjects evaluated the validity of conclusions such as William the Conqueror was king after the Pyramids were built (temporal task) or Manchester is north of Bournemouth (spatial task) with respect to their premises. All of the major findings for equivalent categorical syllogism tasks were replicated. However, the overall size of the main effect of believability appears to be related to task presentation, a phenomenon not previously identified for categorical syllogisms and which current theories of belief bias have difficulty explaining.

  20. Casuistry and social category bias.

    PubMed

    Norton, Michael I; Vandello, Joseph A; Darley, John M

    2004-12-01

    This research explored cases where people are drawn to make judgments between individuals based on questionable criteria, in particular those individuals' social group memberships. We suggest that individuals engage in casuistry to mask biased decision making, by recruiting more acceptable criteria to justify such decisions. We present 6 studies that demonstrate how casuistry licenses people to judge on the basis of social category information but appear unbiased--to both others and themselves--while doing so. In 2 domains (employment and college admissions decisions), with 2 social categories (gender and race), and with 2 motivations (favoring an in-group or out-group), the present studies explored how participants justify decisions biased by social category information by arbitrarily inflating the relative value of their preferred candidates' qualifications over those of competitors.

  1. Addressing Fission Product Validation in MCNP Burnup Credit Criticality Calculations

    SciTech Connect

    Mueller, Don; Bowen, Douglas G; Marshall, William BJ J

    2015-01-01

    The US Nuclear Regulatory Commission (NRC) Division of Spent Fuel Storage and Transportation issued Interim Staff Guidance (ISG) 8, Revision 3 in September 2012. This ISG provides guidance for NRC staff members’ review of burnup credit (BUC) analyses supporting transport and dry storage of pressurized water reactor spent nuclear fuel (SNF) in casks. The ISG includes guidance for addressing validation of criticality (keff) calculations crediting the presence of a limited set of fission products and minor actinides (FP&MAs). Based on previous work documented in NRC Regulatory Guide (NUREG) Contractor Report (CR)-7109, the ISG recommends that NRC staff members accept the use of either 1.5 or 3% of the FP&MA worth—in addition to bias and bias uncertainty resulting from validation of keff calculations for the major actinides in SNF—to conservatively account for the bias and bias uncertainty associated with the specified unvalidated FP&MAs. The ISG recommends (1) use of 1.5% of the FP&MA worth if a modern version of SCALE and its nuclear data are used and (2) 3% of the FP&MA worth for well qualified, industry standard code systems other than SCALE with the Evaluated Nuclear Data Files, Part B (ENDF/B),-V, ENDF/B-VI, or ENDF/B-VII cross sections libraries. The work presented in this paper provides a basis for extending the use of the 1.5% of the FP&MA worth bias to BUC criticality calculations performed using the Monte Carlo N-Particle (MCNP) code. The extended use of the 1.5% FP&MA worth bias is shown to be acceptable by comparison of FP&MA worths calculated using SCALE and MCNP with ENDF/B-V, -VI, and -VII–based nuclear data. The comparison supports use of the 1.5% FP&MA worth bias when the MCNP code is used for criticality calculations, provided that the cask design is similar to the hypothetical generic BUC-32 cask model and that the credited FP&MA worth is no more than 0.1 Δkeff (ISG-8, Rev. 3, Recommendation 4).

  2. Self regulating body bias generator

    NASA Technical Reports Server (NTRS)

    Hass, Kenneth (Inventor)

    2004-01-01

    The back bias voltage on a functional circuit is controlled through a closed loop process. A delay element receives a clock pulse and produces a delay output. The delay element is advantageously constructed of the same materials as the functional circuit so that the aging and degradation of the delay element parallels the degradation of the functional circuit. As the delay element degrades, the transistor switching time increases, increasing the time delay of the delay output. An AND gate compares a clock pulse to an output pulse of the delay element, the AND output forming a control pulse. A duty cycle of the control pulse is determined by the delay time between the clock pulse and the delay element output. The control pulse is received at the input of a charge pump. The charge pump produces a back bias voltage which is then applied to the delay element and to the functional circuit. If the time delay produced by the delay element exceeds the optimal delay, the duty cycle of the control pulse is shortened, and the back bias voltage is lowered, thereby increasing the switching speed of the transistors in the delay element and reducing the time delay. If the throughput of the delay element is too fast, the duty cycle of the control pulse is lengthened, raising the back bias voltage produced by the charge pump. This, in turn, lowers the switching speed of the transistors in both the delay element and the functional circuit. The slower switching speed in the delay element increases time delay. In this manner, the switching speed of the delay element, and of the functional circuit, is maintained at a constant level over the life of the circuit.

  3. Bias in regression estimates of manning's n

    USGS Publications Warehouse

    Wahl, Kenneth L.

    1994-01-01

    Selected equations for estimating roughness for gravel-bed streams were tested using a composite data set containing much of the data used to define the equations. All equations tested were found to significantly underestimate n for relatively low discharges. For floods about equal to the median annual peak discharge, Jarrett's equation overestimates n (median error = 10 percent) while the other equations tested showed no bias. Extrapolation of any of these equations to discharges greater than about 1.5 times the median annual peak discharge is presently unwarranted. The roughness of mountain streams is known to generally decrease as discharge and flow depth increases. The data, however, are presently not available to test the applicability of the equations to large flood discharges.

  4. Reporting bias in medical research - a narrative review.

    PubMed

    McGauran, Natalie; Wieseler, Beate; Kreis, Julia; Schüler, Yvonne-Beatrice; Kölsch, Heike; Kaiser, Thomas

    2010-01-01

    Reporting bias represents a major problem in the assessment of health care interventions. Several prominent cases have been described in the literature, for example, in the reporting of trials of antidepressants, Class I anti-arrhythmic drugs, and selective COX-2 inhibitors. The aim of this narrative review is to gain an overview of reporting bias in the medical literature, focussing on publication bias and selective outcome reporting. We explore whether these types of bias have been shown in areas beyond the well-known cases noted above, in order to gain an impression of how widespread the problem is. For this purpose, we screened relevant articles on reporting bias that had previously been obtained by the German Institute for Quality and Efficiency in Health Care in the context of its health technology assessment reports and other research work, together with the reference lists of these articles.We identified reporting bias in 40 indications comprising around 50 different pharmacological, surgical (e.g. vacuum-assisted closure therapy), diagnostic (e.g. ultrasound), and preventive (e.g. cancer vaccines) interventions. Regarding pharmacological interventions, cases of reporting bias were, for example, identified in the treatment of the following conditions: depression, bipolar disorder, schizophrenia, anxiety disorder, attention-deficit hyperactivity disorder, Alzheimer's disease, pain, migraine, cardiovascular disease, gastric ulcers, irritable bowel syndrome, urinary incontinence, atopic dermatitis, diabetes mellitus type 2, hypercholesterolaemia, thyroid disorders, menopausal symptoms, various types of cancer (e.g. ovarian cancer and melanoma), various types of infections (e.g. HIV, influenza and Hepatitis B), and acute trauma. Many cases involved the withholding of study data by manufacturers and regulatory agencies or the active attempt by manufacturers to suppress publication. The ascertained effects of reporting bias included the overestimation of efficacy

  5. GPCR biased ligands as novel heart failure therapeutics.

    PubMed

    Violin, Jonathan D; Soergel, David G; Boerrigter, Guido; Burnett, John C; Lark, Michael W

    2013-10-01

    G protein-coupled receptors have been successfully targeted by numerous therapeutics including drugs that have transformed the management of cardiovascular disease. However, many GPCRs, when activated or blocked by drugs, elicit both beneficial and adverse pharmacology. Recent work has demonstrated that in some cases, the salutary and deleterious signals linked to a specific GPCR can be selectively targeted by "biased ligands" that entrain subsets of a receptor's normal pharmacology. This review briefly summarizes the advances and current state of the biased ligand field, focusing on an example: biased ligands targeting the angiotensin II type 1 receptor. These compounds exhibit unique pharmacology, distinct from classic agonists or antagonists, and one such molecule is now in clinical development for the treatment of acute heart failure.

  6. [Implications of publication bias on guideline development and appraisal].

    PubMed

    Kopp, Ina B

    2011-01-01

    The issue of selective publishing of research results is gaining more and more scientific, public and political awareness. For guideline authors, in particular, it leads to uncertainty about the interpretability of the methodological quality and clinical relevance of the available evidence and the risk of bias where their conclusions and thus guideline recommendations are concerned. The actual impact of publication bias on guideline contents appears to be low if a systematic and methodically sound approach is followed in the process of guideline development. However, the quality of the evidence on this topic is poor. Different strategies to deal with publication bias have been proposed for authors of systematic reviews but they are of limited use for guideline authors. The goal must therefore be to implement appropriate measures in order to avoid the problem ex ante. The first step would be the systematic registration of study results in publicly accessible registers.

  7. SEASAT altimeter timing bias estimation

    NASA Astrophysics Data System (ADS)

    Marsh, J. G.; Williamson, R. G.

    1982-04-01

    The calibration of the altimeter observation time tags to the millisecond level of accuracy is fundamental to the processing of the data. Initial analyses of the SEASAT altimeter data indicated the presence of a time calibration bias which produced altimeter measurement errors in excess of a meter. A technique has been developed for the solution of the time tag bias based upon the analysis of sea surface height discrepancies at ground track intersections. This technique has permitted very good separation of the dominant once per revolution ephemeris error, which amounts to about 1.5 m rms, from the timing error signature. Furthermore, the technique does not depend upon the availability of precise geoid data. The application of this technique to a global set of SEASAT altimeter data covering the time period of July 28-August 9, 1978, has resulted in a value of -81.0±2 ms for the time tag bias. This value agrees to within 2.9 ms of the value derived at the University of Texas from a similar analysis of the altimeter data. Furthermore, these values corroborate the revised value of -79.4 ms derived at NASA/Wallops Flight Center and the Johns Hopkins University/Applied Physics Lab from a reexamination of the internal instrument time delays. The modeling of oceanic tides and the orbit computations are the major error sources in these analyses.

  8. Generalization of the FRAM's Bias

    SciTech Connect

    Duc T. Vo

    2005-10-01

    The Fixed-Energy Response-Function Analysis with Multiple Efficiency (FRAM) code was developed at Los Alamos National Laboratory to measure the gamma-ray spectrometry of the isotopic composition of plutonium, uranium, and other actinides. Its reported uncertainties of the results come from the propagation of the statistics in the peak areas only. No systematic error components are included in the reported uncertainties. We have done several studies and found that the FRAM's statistical precision can be reasonably represented by its reported uncertainties. The FRAM's biases or systematic uncertainties can come from a variety of sources and can be difficult to determine. We carefully examined the FRAM analytical results of the archival plutonium data and of the data specifically acquired for this isotopic uncertainty analysis project and found the relationship between the bias and other parameters. We worked out the equations representing the biases of the measured isotopes from each measurement using the internal parameters in the spectrum such as peak resolution and shape, region of analysis, and burnup (for plutonium) or enrichment (for uranium).

  9. Response bias in plaintiffs' histories.

    PubMed

    Lees-Haley, P R; Williams, C W; Zasler, N D; Marguilies, S; English, L T; Stevens, K B

    1997-11-01

    This study investigated response bias in self-reported history of factors relevant to the assessment of traumatic brain injury, toxic brain injury and related emotional distress. Response bias refers to systematic error in self-report data. A total of 446 subjects (comprising 131 litigating and 315 non-litigating adults from five locations in the United States) completed a symptom questionnaire. Data were obtained from university faculty and students, from patients in clinics specializing in physiatry neurology, and family medicine, and from plaintiffs undergoing forensic neuropsychological evaluations. Comparisons were made for litigant and non litigant ratings of their past and current cognitive and emotional functioning, including life in general, ability to concentrate, memory, depression, anxiety, alcohol, drugs, ability to work or attend school, irritability, headaches, confusion, self-esteem, and fatigue. Although there is no basis for hypothesizing plaintiffs to be healthier than the general population, plaintiffs rated their pre-injury functioning superior to non-plaintiffs. These findings suggest that response biases need to be taken into account by forensic examiners when relying on litigants' self-reports of pre-injury status.

  10. Addressing Passive Smoking in Children

    PubMed Central

    Hutchinson, Sasha G.; Kuijlaars, Jennifer S.; Mesters, Ilse; Muris, Jean W. M.; van Schayck, Constant P.; Dompeling, Edward; Feron, Frans J. M.

    2014-01-01

    Background A significant number of parents are unaware or unconvinced of the health consequences of passive smoking (PS) in children. Physicians could increase parental awareness by giving personal advice. Aim To evaluate the current practices of three Dutch health professions (paediatricians, youth health care physicians, and family physicians) regarding parental counselling for passive smoking (PS) in children. Methods All physicians (n = 720) representing the three health professions in Limburg, the Netherlands, received an invitation to complete a self-administered electronic questionnaire including questions on their: sex, work experience, personal smoking habits, counselling practices and education regarding PS in children. Results The response rate was 34%. One tenth (11%) of the responding physicians always addressed PS in children, 32% often, 54% occasionally and 4% reported to never attend to it. The three health professions appeared comparable regarding their frequency of parental counselling for PS in children. Addressing PS was more likely when children had respiratory problems. Lack of time was the most frequently mentioned barrier, being very and somewhat applicable for respectively 14% and 43% of the physicians. One fourth of the responders had received postgraduate education about PS. Additionally, 49% of the responders who did not have any education about PS were interested in receiving it. Conclusions Physicians working in the paediatric field in Limburg, the Netherlands, could more frequently address PS in children with parents. Lack of time appeared to be the most mentioned barrier and physicians were more likely to counsel parents for PS in children with respiratory complaints/diseases. Finally, a need for more education on parental counselling for PS was expressed. PMID:24809443

  11. Understanding and Addressing Racial Disparities in Health Care

    PubMed Central

    Williams, David R.; Rucker, Toni D.

    2000-01-01

    Racial disparities in medical care should be understood within the context of racial inequities in societal institutions. Systematic discrimination is not the aberrant behavior of a few but is often supported by institutional policies and unconscious bias based on negative stereotypes. Effectively addressing disparities in the quality of care requires improved data systems, increased regulatory vigilance, and new initiatives to appropriately train medical professionals and recruit more providers from disadvantaged minority backgrounds. Identifying and implementing effective strategies to eliminate racial inequities in health status and medical care should be made a national priority. PMID:11481746

  12. Addressing inequities in healthy eating.

    PubMed

    Friel, Sharon; Hattersley, Libby; Ford, Laura; O'Rourke, Kerryn

    2015-09-01

    What, when, where and how much people eat is influenced by a complex mix of factors at societal, community and individual levels. These influences operate both directly through the food system and indirectly through political, economic, social and cultural pathways that cause social stratification and influence the quality of conditions in which people live their lives. These factors are the social determinants of inequities in healthy eating. This paper provides an overview of the current evidence base for addressing these determinants and for the promotion of equity in healthy eating. PMID:26420812

  13. Identifying and Addressing Vaccine Hesitancy

    PubMed Central

    Kestenbaum, Lori A.; Feemster, Kristen A.

    2015-01-01

    In the 20th century, the introduction of multiple vaccines significantly reduced childhood morbidity, mortality, and disease outbreaks. Despite, and perhaps because of, their public health impact, an increasing number of parents and patients are choosing to delay or refuse vaccines. These individuals are described as vaccine hesitant. This phenomenon has developed due to the confluence of multiple social, cultural, political and personal factors. As immunization programs continue to expand, understanding and addressing vaccine hesitancy will be crucial to their successful implementation. This review explores the history of vaccine hesitancy, its causes, and suggested approaches for reducing hesitancy and strengthening vaccine acceptance. PMID:25875982

  14. Addressing the workforce pipeline challenge

    SciTech Connect

    Leonard Bond; Kevin Kostelnik; Richard Holman

    2006-11-01

    A secure and affordable energy supply is essential for achieving U.S. national security, in continuing U.S. prosperity and in laying the foundations to enable future economic growth. To meet this goal the next generation energy workforce in the U.S., in particular those needed to support instrumentation, controls and advanced operations and maintenance, is a critical element. The workforce is aging and a new workforce pipeline, to support both current generation and new build has yet to be established. The paper reviews the challenges and some actions being taken to address this need.

  15. A Novel Method for Analyzing Extremely Biased Agonism at G Protein–Coupled Receptors

    PubMed Central

    Zhou, Lei; Ehlert, Frederick J.; Bohn, Laura M.

    2015-01-01

    Seven transmembrane receptors were originally named and characterized based on their ability to couple to heterotrimeric G proteins. The assortment of coupling partners for G protein–coupled receptors has subsequently expanded to include other effectors (most notably the βarrestins). This diversity of partners available to the receptor has prompted the pursuit of ligands that selectively activate only a subset of the available partners. A biased or functionally selective ligand may be able to distinguish between different active states of the receptor, and this would result in the preferential activation of one signaling cascade more than another. Although application of the “standard” operational model for analyzing ligand bias is useful and suitable in most cases, there are limitations that arise when the biased agonist fails to induce a significant response in one of the assays being compared. In this article, we describe a quantitative method for measuring ligand bias that is particularly useful for such cases of extreme bias. Using simulations and experimental evidence from several κ opioid receptor agonists, we illustrate a “competitive” model for quantitating the degree and direction of bias. By comparing the results obtained from the competitive model with the standard model, we demonstrate that the competitive model expands the potential for evaluating the bias of very partial agonists. We conclude the competitive model provides a useful mechanism for analyzing the bias of partial agonists that exhibit extreme bias. PMID:25680753

  16. The Probability Distribution for a Biased Spinner

    ERIC Educational Resources Information Center

    Foster, Colin

    2012-01-01

    This article advocates biased spinners as an engaging context for statistics students. Calculating the probability of a biased spinner landing on a particular side makes valuable connections between probability and other areas of mathematics. (Contains 2 figures and 1 table.)

  17. Attention bias for sexual words in females with low sexual functioning: A brief report

    PubMed Central

    Beard, Courtney; Amir, Nader

    2014-01-01

    Attention bias (i.e., tendency to selectively attend to disorder-relevant stimuli) has been associated with numerous emotional disorders, but few studies have examined attention bias in the context of sexual problems. The current study tested the hypothesis that females with low sexual functioning show an attention bias toward sexual stimuli compared to females with high sexual functioning. We assessed attention bias using a modified probe detection task using sexual and neutral words. Females with low sexual functioning (n=25) showed an attention bias toward sexual words, whereas females with high sexual functioning (n=25) did not. These results suggest that attention bias may be involved in the maintenance of female sexual dysfunction. Moreover, our findings have implications for both models of sexual dysfunction, as well as clinical interventions. PMID:20432123

  18. The Nonverbal Transmission of Intergroup Bias: A Model of Bias Contagion with Implications for Social Policy

    PubMed Central

    Weisbuch, Max; Pauker, Kristin

    2013-01-01

    Social and policy interventions over the last half-century have achieved laudable reductions in blatant discrimination. Yet members of devalued social groups continue to face subtle discrimination. In this article, we argue that decades of anti-discrimination interventions have failed to eliminate intergroup bias because such bias is contagious. We present a model of bias contagion in which intergroup bias is subtly communicated through nonverbal behavior. Exposure to such nonverbal bias “infects” observers with intergroup bias. The model we present details two means by which nonverbal bias can be expressed—either as a veridical index of intergroup bias or as a symptom of worry about appearing biased. Exposure to this nonverbal bias can increase perceivers’ own intergroup biases through processes of implicit learning, informational influence, and normative influence. We identify critical moderators that may interfere with these processes and consequently propose several social and educational interventions based on these moderators. PMID:23997812

  19. Fluid simulation of the bias effect in inductive/capacitive discharges

    SciTech Connect

    Zhang, Yu-Ru; Gao, Fei; Li, Xue-Chun; Wang, You-Nian; Bogaerts, Annemie

    2015-11-15

    Computer simulations are performed for an argon inductively coupled plasma (ICP) with a capacitive radio-frequency bias power, to investigate the bias effect on the discharge mode transition and on the plasma characteristics at various ICP currents, bias voltages, and bias frequencies. When the bias frequency is fixed at 13.56 MHz and the ICP current is low, e.g., 6 A, the spatiotemporal averaged plasma density increases monotonically with bias voltage, and the bias effect is already prominent at a bias voltage of 90 V. The maximum of the ionization rate moves toward the bottom electrode, which indicates clearly the discharge mode transition in inductive/capacitive discharges. At higher ICP currents, i.e., 11 and 13 A, the plasma density decreases first and then increases with bias voltage, due to the competing mechanisms between the ion acceleration power dissipation and the capacitive power deposition. At 11 A, the bias effect is still important, but it is noticeable only at higher bias voltages. At 13 A, the ionization rate is characterized by a maximum at the reactor center near the dielectric window at all selected bias voltages, which indicates that the ICP power, instead of the bias power, plays a dominant role under this condition, and no mode transition is observed. Indeed, the ratio of the bias power to the total power is lower than 0.4 over a wide range of bias voltages, i.e., 0–300 V. Besides the effect of ICP current, also the effect of various bias frequencies is investigated. It is found that the modulation of the bias power to the spatiotemporal distributions of the ionization rate at 2 MHz is strikingly different from the behavior observed at higher bias frequencies. Furthermore, the minimum of the plasma density appears at different bias voltages, i.e., 120 V at 2 MHz and 90 V at 27.12 MHz.

  20. Biased learning affects mate choice in a butterfly

    PubMed Central

    Westerman, Erica L.; Hodgins-Davis, Andrea; Dinwiddie, April; Monteiro, Antónia

    2012-01-01

    Early acquisition of mate preferences or mate-preference learning is associated with signal diversity and speciation in a wide variety of animal species. However, the diversity of mechanisms of mate-preference learning across taxa remains poorly understood. Using the butterfly Bicyclus anynana we uncover a mechanism that can lead to directional sexual selection via mate-preference learning: a bias in learning enhanced ornamentation, which is independent of preexisting mating biases. Naïve females mated preferentially with wild-type males over males with enhanced wing ornamentation, but females briefly exposed to enhanced males mated significantly more often with enhanced males. In contrast, females exposed to males with reduced wing ornamentation did not learn to prefer drab males. Thus, we observe both a learned change of a preexisting mating bias, and a bias in ability to learn enhanced male ornaments over reduced ornaments. Our findings demonstrate that females are able to change their preferences in response to a single social event, and suggest a role for biased learning in the evolution of visual sexual ornamentation. PMID:22689980

  1. Optimized tuner selection for engine performance estimation

    NASA Technical Reports Server (NTRS)

    Simon, Donald L. (Inventor); Garg, Sanjay (Inventor)

    2013-01-01

    A methodology for minimizing the error in on-line Kalman filter-based aircraft engine performance estimation applications is presented. This technique specifically addresses the underdetermined estimation problem, where there are more unknown parameters than available sensor measurements. A systematic approach is applied to produce a model tuning parameter vector of appropriate dimension to enable estimation by a Kalman filter, while minimizing the estimation error in the parameters of interest. Tuning parameter selection is performed using a multi-variable iterative search routine which seeks to minimize the theoretical mean-squared estimation error. Theoretical Kalman filter estimation error bias and variance values are derived at steady-state operating conditions, and the tuner selection routine is applied to minimize these values. The new methodology yields an improvement in on-line engine performance estimation accuracy.

  2. Gender Bias: Recent Research and Interventions.

    ERIC Educational Resources Information Center

    New Jersey Research Bulletin, 1996

    1996-01-01

    This annotated bibliography lists 14 publications about recent research on gender bias and interventions to reduce gender bias in schools. The bibliography is divided into two sections: current research and intervention. The first includes descriptions of studies examining the following topics: gender bias in U.S. schools and its effects;…

  3. Outcome-Reporting Bias in Education Research

    ERIC Educational Resources Information Center

    Pigott, Therese D.; Valentine, Jeffrey C.; Polanin, Joshua R.; Williams, Ryan T.; Canada, Dericka D.

    2013-01-01

    Outcome-reporting bias occurs when primary studies do not include information about all outcomes measured in a study. When studies omit findings on important measures, efforts to synthesize the research using systematic review techniques will be biased and interpretations of individual studies will be incomplete. Outcome-reporting bias has been…

  4. Attentional Bias for Exercise-Related Images

    ERIC Educational Resources Information Center

    Berry, Tanya R.; Spence, John C.; Stolp, Sean M.

    2011-01-01

    This research examined attentional bias toward exercise-related images using a visual probe task. It was hypothesized that more-active participants would display attentional bias toward the exercise-related images. The results showed that men displayed attentional bias for the exercise images. There was a significant interaction of activity level…

  5. Using Newspapers to Study Media Bias.

    ERIC Educational Resources Information Center

    Kirman, Joseph M.

    1992-01-01

    Suggests that students can learn to recognize media bias by studying media reports of current events or historical topics. Describes a study unit using media coverage of the second anniversary of the Palestinian uprising against Israel. Discusses lesson objectives, planning, defining bias teaching procedures, and criteria for determining bias. (DK)

  6. Culturally Biased Assumptions in Counseling Psychology

    ERIC Educational Resources Information Center

    Pedersen, Paul B.

    2003-01-01

    Eight clusters of culturally biased assumptions are identified for further discussion from Leong and Ponterotto's (2003) article. The presence of cultural bias demonstrates that cultural bias is so robust and pervasive that is permeates the profession of counseling psychology, even including those articles that effectively attack cultural bias…

  7. Sexual selection.

    PubMed

    Hosken, David J; House, Clarissa M

    2011-01-25

    Sexual selection is a concept that has probably been misunderstood and misrepresented more than any other idea in evolutionary biology, confusion that continues to the present day. We are not entirely sure why this is, but sexual politics seems to have played its role, as does a failure to understand what sexual selection is and why it was initially invoked. While in some ways less intuitive than natural selection, sexual selection is conceptually identical to it, and evolution via either mechanism will occur given sufficient genetic variation. Recent claims that sexual selection theory is fundamentally flawed are simply wrong and ignore an enormous body of evidence that provides a bedrock of support for this major mechanism of organic evolution. In fact it is partly due to this solid foundation that current research has largely shifted from documenting whether or not sexual selection occurs, to addressing more complex evolutionary questions. PMID:21256434

  8. An independent sequential maximum likelihood approach to simultaneous track-to-track association and bias removal

    NASA Astrophysics Data System (ADS)

    Song, Qiong; Wang, Yuehuan; Yan, Xiaoyun; Liu, Dang

    2015-12-01

    In this paper we propose an independent sequential maximum likelihood approach to address the joint track-to-track association and bias removal in multi-sensor information fusion systems. First, we enumerate all kinds of association situation following by estimating a bias for each association. Then we calculate the likelihood of each association after bias compensated. Finally we choose the maximum likelihood of all association situations as the association result and the corresponding bias estimation is the registration result. Considering the high false alarm and interference, we adopt the independent sequential association to calculate the likelihood. Simulation results show that our proposed method can give out the right association results and it can estimate the bias precisely simultaneously for small number of targets in multi-sensor fusion system.

  9. Multi-Sensor Consensus Estimation of State, Sensor Biases and Unknown Input.

    PubMed

    Zhou, Jie; Liang, Yan; Yang, Feng; Xu, Linfeng; Pan, Quan

    2016-09-01

    This paper addresses the problem of the joint estimation of system state and generalized sensor bias (GSB) under a common unknown input (UI) in the case of bias evolution in a heterogeneous sensor network. First, the equivalent UI-free GSB dynamic model is derived and the local optimal estimates of system state and sensor bias are obtained in each sensor node; Second, based on the state and bias estimates obtained by each node from its neighbors, the UI is estimated via the least-squares method, and then the state estimates are fused via consensus processing; Finally, the multi-sensor bias estimates are further refined based on the consensus estimate of the UI. A numerical example of distributed multi-sensor target tracking is presented to illustrate the proposed filter.

  10. Multi-Sensor Consensus Estimation of State, Sensor Biases and Unknown Input

    PubMed Central

    Zhou, Jie; Liang, Yan; Yang, Feng; Xu, Linfeng; Pan, Quan

    2016-01-01

    This paper addresses the problem of the joint estimation of system state and generalized sensor bias (GSB) under a common unknown input (UI) in the case of bias evolution in a heterogeneous sensor network. First, the equivalent UI-free GSB dynamic model is derived and the local optimal estimates of system state and sensor bias are obtained in each sensor node; Second, based on the state and bias estimates obtained by each node from its neighbors, the UI is estimated via the least-squares method, and then the state estimates are fused via consensus processing; Finally, the multi-sensor bias estimates are further refined based on the consensus estimate of the UI. A numerical example of distributed multi-sensor target tracking is presented to illustrate the proposed filter. PMID:27598156

  11. Multi-Sensor Consensus Estimation of State, Sensor Biases and Unknown Input.

    PubMed

    Zhou, Jie; Liang, Yan; Yang, Feng; Xu, Linfeng; Pan, Quan

    2016-01-01

    This paper addresses the problem of the joint estimation of system state and generalized sensor bias (GSB) under a common unknown input (UI) in the case of bias evolution in a heterogeneous sensor network. First, the equivalent UI-free GSB dynamic model is derived and the local optimal estimates of system state and sensor bias are obtained in each sensor node; Second, based on the state and bias estimates obtained by each node from its neighbors, the UI is estimated via the least-squares method, and then the state estimates are fused via consensus processing; Finally, the multi-sensor bias estimates are further refined based on the consensus estimate of the UI. A numerical example of distributed multi-sensor target tracking is presented to illustrate the proposed filter. PMID:27598156

  12. Addressing viral resistance through vaccines

    PubMed Central

    Laughlin, Catherine; Schleif, Amanda; Heilman, Carole A

    2015-01-01

    Antimicrobial resistance is a serious healthcare concern affecting millions of people around the world. Antiviral resistance has been viewed as a lesser threat than antibiotic resistance, but it is important to consider approaches to address this growing issue. While vaccination is a logical strategy, and has been shown to be successful many times over, next generation viral vaccines with a specific goal of curbing antiviral resistance will need to clear several hurdles including vaccine design, evaluation and implementation. This article suggests that a new model of vaccination may need to be considered: rather than focusing on public health, this model would primarily target sectors of the population who are at high risk for complications from certain infections. PMID:26604979

  13. Changing concepts: the presidential address.

    PubMed

    Weed, J C

    1974-09-01

    A discussion of conceptual change in areas related to fertility and medicine is presented in an address by the president of the American Fertility Society. Advances in technological research and medicine, particularly in steroids and reporductive physiology, have been the most readily acceptable changes. Cesarean section and surgical sterilization have also become increasingly accepted. Newer developments such as sperm banks, artificial insemination, and ovum transfer have created profound ethical, moral, and medical issued in human engineering research and evolutionary theory. The legalization of abortion has brought moral, ethical, and legal problems for many members of the medical profession. It is urged that the Society promote education of the people in reproductive function, sexual activity, and parental obligation while being acutely aware of the problems in influencing or altering human reproduction.

  14. Addressing Failures in Exascale Computing

    SciTech Connect

    Snir, Marc; Wisniewski, Robert; Abraham, Jacob; Adve, Sarita; Bagchi, Saurabh; Balaji, Pavan; Belak, J.; Bose, Pradip; Cappello, Franck; Carlson, Bill; Chien, Andrew; Coteus, Paul; DeBardeleben, Nathan; Diniz, Pedro; Engelmann, Christian; Erez, Mattan; Fazzari, Saverio; Geist, Al; Gupta, Rinku; Johnson, Fred; Krishnamoorthy, Sriram; Leyffer, Sven; Liberty, Dean; Mitra, Subhasish; Munson, Todd; Schreiber, Rob; Stearley, Jon; Van Hensbergen, Eric

    2014-01-01

    We present here a report produced by a workshop on Addressing failures in exascale computing' held in Park City, Utah, 4-11 August 2012. The charter of this workshop was to establish a common taxonomy about resilience across all the levels in a computing system, discuss existing knowledge on resilience across the various hardware and software layers of an exascale system, and build on those results, examining potential solutions from both a hardware and software perspective and focusing on a combined approach. The workshop brought together participants with expertise in applications, system software, and hardware; they came from industry, government, and academia, and their interests ranged from theory to implementation. The combination allowed broad and comprehensive discussions and led to this document, which summarizes and builds on those discussions.

  15. Addressing failures in exascale computing

    SciTech Connect

    Snir, Marc; Wisniewski, Robert W.; Abraham, Jacob A.; Adve, Sarita; Bagchi, Saurabh; Balaji, Pavan; Belak, Jim; Bose, Pradip; Cappello, Franck; Carlson, William; Chien, Andrew A.; Coteus, Paul; Debardeleben, Nathan A.; Diniz, Pedro; Engelmann, Christian; Erez, Mattan; Saverio, Fazzari; Geist, Al; Gupta, Rinku; Johnson, Fred; Krishnamoorthy, Sriram; Leyffer, Sven; Liberty, Dean; Mitra, Subhasish; Munson, Todd; Schreiber, Robert; Stearly, Jon; Van Hensbergen, Eric

    2014-05-01

    We present here a report produced by a workshop on “Addressing Failures in Exascale Computing” held in Park City, Utah, August 4–11, 2012. The charter of this workshop was to establish a common taxonomy about resilience across all the levels in a computing system; discuss existing knowledge on resilience across the various hardware and software layers of an exascale system; and build on those results, examining potential solutions from both a hardware and software perspective and focusing on a combined approach. The workshop brought together participants with expertise in applications, system software, and hardware; they came from industry, government, and academia; and their interests ranged from theory to implementation. The combination allowed broad and comprehensive discussions and led to this document, which summarizes and builds on those discussions.

  16. Light addressable photoelectrochemical cyanide sensor

    SciTech Connect

    Licht, S.; Myung, N.; Sun, Y.

    1996-03-15

    A sensor is demonstrated that is capable of spatial discrimination of cyanide with use of only a single stationary sensing element. Different spatial regions of the sensing element are light activated to reveal the solution cyanide concentration only at the point of illumination. In this light addressable photoelectrochemical (LAP) sensor the sensing element consists of an n-CdSe electrode immersed in solution, with the open-circuit potential determined under illumination. In alkaline ferro-ferri-cyanide solution, the open-circuit photopotential is highly responsive to cyanide, with a linear response of (120 mV) log [KCN]. LAP detection with a spatial resolution of {+-}1 mm for cyanide detection is demonstrated. The response is almost linear for 0.001-0.100 m cyanide with a resolution of 5 mV. 38 refs., 7 figs., 1 tab.

  17. Investigation of bias in a study of nuclear shipyard workers

    SciTech Connect

    Greenberg, E.R.; Rosner, B.; Hennekens, C.; Rinsky, R.; Colton, T.

    1985-02-01

    The authors examined discrepant findings between a 1978 proportional mortality study and a 1981 cohort study of workers at the Portsmouth, New Hampshire Naval Shipyard to determine whether the healthy worker effect, selection bias, or measurement bias could explain why only the proportional mortality study found excess cancer deaths among nuclear workers. Lower mortality from noncancer causes in nuclear workers (the healthy worker effect) partly accounted for the observed elevated cancer proportional mortality. More important, however, was measurement bias which occurred in the proportional mortality study when nuclear workers who had not died of cancer were misclassified as not being nuclear workers based on information from their next of kin, thereby, creating a spurious association. Although the proportional mortality study was based on a small sample of all deaths occuring in the cohort, selection bias did not contribute materially to the discrepant results for total cancer deaths. With regard to leukemia, misclassification of occupation in the proportional mortality study and disagreement about cause of death accounted for some of the reported excess deaths. 16 references, 4 tables.

  18. Sex-biased transcriptome evolution in Drosophila.

    PubMed

    Assis, Raquel; Zhou, Qi; Bachtrog, Doris

    2012-01-01

    Sex-biased genes are thought to drive phenotypic differences between males and females. The recent availability of high-throughput gene expression data for many related species has led to a burst of investigations into the genomic and evolutionary properties of sex-biased genes. In Drosophila, a number of studies have found that X chromosomes are deficient in male-biased genes (demasculinized) and enriched for female-biased genes (feminized) and that male-biased genes evolve faster than female-biased genes. However, studies have yielded vastly different conclusions regarding the numbers of sex-biased genes and forces shaping their evolution. Here, we use RNA-seq data from multiple tissues of Drosophila melanogaster and D. pseudoobscura, a species with a recently evolved X chromosome, to explore the evolution of sex-biased genes in Drosophila. First, we compare several independent metrics for classifying sex-biased genes and find that the overlap of genes identified by different metrics is small, particularly for female-biased genes. Second, we investigate genome-wide expression patterns and uncover evidence of demasculinization and feminization of both ancestral and new X chromosomes, demonstrating that gene content on sex chromosomes evolves rapidly. Third, we examine the evolutionary rates of sex-biased genes and show that male-biased genes evolve much faster than female-biased genes, which evolve at similar rates to unbiased genes. Analysis of gene expression among tissues reveals that this trend may be partially due to pleiotropic effects of female-biased genes, which limits their evolutionary potential. Thus, our findings illustrate the importance of accurately identifying sex-biased genes and provide insight into their evolutionary dynamics in Drosophila.

  19. Bioethicists Can and Should Contribute to Addressing Racism.

    PubMed

    Danis, Marion; Wilson, Yolonda; White, Amina

    2016-01-01

    The problems of racism and racially motivated violence in predominantly African American communities in the United States are complex, multifactorial, and historically rooted. While these problems are also deeply morally troubling, bioethicists have not contributed substantially to addressing them. Concern for justice has been one of the core commitments of bioethics. For this and other reasons, bioethicists should contribute to addressing these problems. We consider how bioethicists can offer meaningful contributions to the public discourse, research, teaching, training, policy development, and academic scholarship in response to the alarming and persistent patterns of racism and implicit biases associated with it. To make any useful contribution, bioethicists will require preparation and should expect to play a significant role through collaborative action with others.

  20. The mixed impact of medical school on medical students’ implicit and explicit weight bias

    PubMed Central

    Puhl, Rebecca M.; Burke, Sara E.; Hardeman, Rachel; Dovidio, John F.; Nelson, David B.; Przedworski, Julia; Burgess, Diana J.; Perry, Sylvia; Yeazel, Mark W.; van Ryn, Michelle

    2016-01-01

    Background Healthcare trainees demonstrate implicit (automatic, unconscious) and explicit (conscious) bias against people from stigmatized and marginalized social groups, which can negatively influence communication and decision-making. Medical schools are well positioned to intervene and reduce bias in new physicians. Objective To assess medical school factors that influence change in implicit and explicit bias against individuals from one stigmatized group, people with obesity. Design Prospective cohort study of medical students enrolled at 49 US medical schools randomly selected from all US medical schools within strata of public/private schools and region. Participants 1,795 medical students surveyed at the beginning of their 1st year and end of their 4th year. Measurement Web-based surveys included measures of weight bias, and medical school experiences and climate. We compared bias change to changes in the general public over the same time period. We used linear mixed models to assess the impact of curriculum, contact with people who have obesity, and faculty role-modeling on weight bias change. Results Increased implicit and explicit biases were associated with less positive contact with patients who have obesity and more exposure to faculty role-modeling of discriminatory behavior or negative comments about patients with obesity. Increased implicit bias was associated with training in how to deal with difficult patients. On average, implicit weight bias decreased and explicit bias increased during medical school, over a period of time where implicit weight bias in the general public increased and explicit bias remained stable. Conclusion Medical schools may reduce students’ weight biases by increasing positive contact between students and patients with obesity, eliminating unprofessional role-modeling by faculty and residents, and altering curricula focused on treating difficult patients. PMID:26383070