Using rewards and penalties to obtain desired subject performance

Operant conditioning procedures, specifically the use of negative reinforcement, in achieving stable learning behavior is described. The critical tracking test (CTT) a method of detecting human operator impairment was tested. A pass level is set for each subject, based on that subject's asymptotic skill level while sober. It is critical that complete training take place before the individualized pass level is set in order that the impairment can be detected. The results provide a more general basis for the application of reward/penalty structures in manual control research

The effects of alcohol on driver performance in a decision making situation

The results are reviewed of driving simulator and in-vehicle field test experiments of alcohol effects on driver risk taking. The objective was to investigate changes in risk taking under alcoholic intoxication and relate these changes to effects on traffic safety. The experiments involved complex 15 minute driving scenarios requiring decision making and steering and speed control throughout a series of typical driving situations. Monetary rewards and penalties were employed to simulate the real-world motivations inherent in driving. A full placebo experimental design was employed, and measures related to traffic safety, driver/vehicle performance and driver behavior were obtained. Alcohol impairment was found to increase the rate of accidents and speeding tickets. Behavioral measures showed these traffic safety effects to be due to impaired psychomotor performance and perceptual distortions. Subjective estimates of risk failed to show any change in the driver's willingness to take risks when intoxicated

The Distributed Annotation System

BACKGROUND: Currently, most genome annotation is curated by centralized groups with limited resources. Efforts to share annotations transparently among multiple groups have not yet been satisfactory. RESULTS: Here we introduce a concept called the Distributed Annotation System (DAS). DAS allows sequence annotations to be decentralized among multiple third-party annotators and integrated on an as-needed basis by client-side software. The communication between client and servers in DAS is defined by the DAS XML specification. Annotations are displayed in layers, one per server. Any client or server adhering to the DAS XML specification can participate in the system; we describe a simple prototype client and server example. CONCLUSIONS: The DAS specification is being used experimentally by Ensembl, WormBase, and the Berkeley Drosophila Genome Project. Continued success will depend on the readiness of the research community to adopt DAS and provide annotations. All components are freely available from the project website

South African Stress and Health (SASH) study : 12-month and lifetime prevalence of common mental disorders

The original publication is available at http://www.samj.org.zaBackground. The South African Stress and Health (SASH) study is the first large-scale population-based study of common mental disorders in the country. This paper provides data on the 12-month and lifetime prevalence of these conditions. Methods. Data from a nationally representative sample of 4 351 adults were analysed. Mental disorders were assessed with the Composite International Diagnostic Interview (CIDI). An extensive survey questionnaire detailed contextual and socio-demographic factors, onset and course of mental disorders, and risk factors. Simple weighted cross-tabulation methods were used to estimate prevalence, and logistic regression analysis was used to study correlates of 12-month and lifetime prevalence. Results. The lifetime prevalence for any disorder was 30.3%, and the most prevalent 12-month and lifetime disorders were the anxiety disorders. The Western Cape had the highest 12-month and lifetime prevalence rates, and the lowest rates were in the Northern Cape. Conclusions. The SASH study shows relatively high 12-month and lifetime prevalence rates. These findings have significant implications for planning mental health services.Publishers' versio

Impact of common mental disorders during childhood and adolescence on secondary school completion

There are few data from South Africa and other low- and middle-income countries on how mental disorders in childhood and adolescence may influence different aspects of socio-economic position, including educational attainment. We examined the association between early-onset disorders and subsequent educational achievement in a nationally representative sample of 4 351 South African adults. After adjusting for participant demographic characteristics and traumatic life events, post-traumatic stress disorder, major depressive disorder and substance-related disorders were each associated with increased odds of failing to complete secondary education (odds ratios and 95% confidence intervals 2.3, 1.0 - 5.1; 1.7, 1.2 - 2.5, and 1.7, 1.2 - 2.5, respectively). These data point to the role that early-life mental disorders may play in educational achievement and subsequent socio-economic position over the life course

The South African Stress and Health (SASH) study: 12-month and lifetime prevalence of common mental disorders

Background. The South African Stress and Health (SASH) study is the first large-scale population-based study of common mental disorders in the country. This paper provides data on the 12-month and lifetime prevalence of these conditions. Methods. Data from a nationally representative sample of 4 351 adults were analysed. Mental disorders were assessed with the Composite International Diagnostic Interview (CIDI). An extensive survey questionnaire detailed contextual and socio-demographic factors, onset and course of mental disorders, and risk factors. Simple weighted cross-tabulation methods were used to estimate prevalence, and logistic regression analysis was used to study correlates of 12-month and lifetime prevalence. Results. The lifetime prevalence for any disorder was 30.3%, and the most prevalent 12-month and lifetime disorders were the anxiety disorders. The Western Cape had the highest 12-month and lifetime prevalence rates, and the lowest rates were in the Northern Cape. Conclusions. The SASH study shows relatively high 12-month and lifetime prevalence rates. These findings have significant implications for planning mental health services

Detection of Bulk Motions in the ICM of the Centaurus Cluster

Several recent numerical simulations of off-center cluster mergers predict that significant angular momentum with associated velocities of a few x 10^{3} km/s can be imparted to the resulting cluster. Such gas bulk velocities can be detected by the Doppler shift of X-ray spectral lines with ASCA spectrometers. Using two ASCA observations of the Centaurus cluster, we produced a velocity map for the gas in the cluster's central regions. We also detected radial and azimuthal gradients in temperature and metal abundance distributions, which seem to be associated with the infalling sub-group centered at NGC 4709 (Cen 45). More importantly, we found a significant (>99.8% confidence level) velocity gradient along a line near-perpendicular to the direction of the incoming sub-group and with a maximum velocity difference of ~3.4+-1.1 x 10^{3} km/s. It is unlikely (P < 0.002) that the observed velocity gradient is generated by gain fluctuations across the detectors. While the observed azimuthal temperature and abundance variations can be attributed to the interaction with Cen 45, we argue that the intracluster gas velocity gradient is more likely due to a previous off-center merging event in the main body of the Centaurus cluster.Comment: 13 pages in emulateapj5 style, 8 postscript figures; Accepted by ApJ; Revised version with minor change

Can clinical audits be enhanced by pathway simulation and machine learning? An example from the acute stroke pathway

OBJECTIVE: To evaluate the application of clinical pathway simulation in machine learning, using clinical audit data, in order to identify key drivers for improving use and speed of thrombolysis at individual hospitals

Using coloured filters to reduce the symptoms of visual stress in children with reading delay

Background: Meares Irlen Syndrome (MIS), otherwise known as “visual stress”, is one condition that can cause difficulties with reading. Aim: This study aimed to compare the effect of two coloured-filter systems on the symptoms of visual stress in children with reading delay. Methods: The study design was a pre-test, post-test, randomized head-to-head comparison of two filter systems on the symptoms of visual stress in school children. A total of 68 UK mainstream schoolchildren with significant impairment in reading ability completed the study. Results: The filter systems appeared to have a large effect on the reported symptoms between pre and post three-month time points (d = 2.5, r = 0.78). Both filter types appeared to have large effects (Harris d = 1.79, r = 0.69 and DRT d = 3.22, r = 0.85). Importantly, 35% of participants’ reported that their symptoms had resolved completely; 72% of the 68 children appeared to gain improvements in three or more visual stress symptoms. Conclusion and significance: The reduction in symptoms, which appeared to be brought about by the use of coloured filters, eased the visual discomfort experienced by these children when reading. This type of intervention therefore has the potential to facilitate occupational engagement

Perceived discrimination and mental health disorders : the South African Stress and Health study (SASH)

The original publication is available at http://www.samj.org.zaObjectives. To describe the demographic correlates of perceived discrimination and explore the association between perceived discrimination and psychiatric disorders. Design. A national household survey was conducted between 2002 and 2004 using the World Health Organization Composite International Diagnostic Interview (CIDI) to generate diagnoses of psychiatric disorders. Additional instruments provided data on perceived discrimination and related variables. Setting. A nationally representative sample of adults in South Africa. Subjects. 4 351 individuals aged 18 years and older. Outcomes. 12-month and lifetime mood, anxiety and substance use disorders. Results. In the multivariate analyses, acute and chronic racial discrimination were associated with an elevated risk of any 12-month DSM-IV disorder when adjusted for socio-demographic factors, but this association was no longer statistically significant when adjusted for other sources of social stress. In fully adjusted models, acute racial discrimination was associated with an elevated risk of lifetime substance use disorders. Acute and chronic non-racial discrimination were associated with an elevated risk of 12-month and lifetime rates of any disorder, even after adjustment for other stressors and potentially confounding psychological factors. The association of chronic non-racial discrimination and 12-month and lifetime disorder was evident across mood, anxiety, and substance use disorders in the fully adjusted models. Conclusion. The risk of psychiatric disorders is elevated among persons who report experiences of discrimination. These associations are more robust for chronic than for acute discrimination and for non-racial than for racial discrimination. Perceived discrimination constitutes an important stressor that should be taken into account in the aetiology of psychiatric disorders.Publishers' versio