Units of algebraic numberfields

AbstractLet K be an algebraic number field with proper subfield k. If K and k have the same number of fundamental units then relations between the units of K and k are obtained

Reducing substance use and sexual risk behaviour among men who have sex with men in South Africa

Abstract Men who have sex with men have been identified as a population at risk of acquiring and transmitting HIV. Studies in South Africa have reported a high prevalence of HIV, as well as high levels of alcohol and other drug use, among men who have sex with men, and the use of substances (alcohol and drugs) to facilitate their sexual encounters. Since 2007, interventions focused on prevention have been rolled out to vulnerable men who have sex with men and who also use alcohol or other drugs. The interventions include community-based outreach; provision of information on HIV/AIDS, substance abuse, and safer sex practices; and the development of risk-reduction plans. Among 195 men who participated in our study, there were significant reductions in the proportion who used cannabis and ecstasy, including the use of these drugs during sex. No reduction was observed in the use of any other substances. In general, after the intervention our participants reported less frequent use of alcohol and drugs and greater engagement in safer sexual practices. Despite these encouraging findings, the combination of substance use while engaging in sex had actually increased. The study findings suggest that interventions that target men who have sex with men, and who use alcohol and other drugs, could reduce risk behaviours in this population

The use of correspondence analysis in building loglinear models

Data collected in the biomedical and social sciences by means of questionnaires is in most instances qualitative in nature. Such data, typically set out in the form of (multi-dimensional) contingency tables, is usually subjected to hypothesis testing in order to assess the interrelationships between the questions. Prior to undertaking confirmatory procedures, we argue that exploratory techniques should be used to gain a "feel" for the data. Correspondence Analysis (an exploratory data analysis procedure) and Log-linear Model building (a confirmatory data analysis procedure) are discussed before an investigation is undertaken to ascertain whether they can be used in conjunction. We found that correspondence analysis : (i) detects questions that are "strictly" independent/unrelated, (ii) detects pairwise relationships between questions (2-factor interactions) and thus can be used to suggest a splitting of large data sets into two or more subsets of questions that are independent, each of which can be analysed separately, and (iii) cannot be used to select log-linear models in general because it does not detect higher order interactions

Access to substance abuse treatment services for black South Africans: findings from audits of specialist treatment facilities in Cape Town and Gauteng: original article

Background: The increased demand for substance abuse treatment has led to concern about the accessibility of existing services to black South Africans. To date, research has not examined the accessibility of services, even though access has been shown to impact on retention and treatment outcomes. Method: Cross-sectional audits of substance abuse treatment facilities were conducted in Cape Town (2002) and Gauteng (2003). Data on client characteristics, facility characteristics, and service delivery characteristics were collected using the Treatment Services Audit questionnaire. Aims: To describe the extent to which substance abuse treatment services are accessible to black clients and the extent to which facilities target barriers that restrict black clients from accessing substance abuse treatment. Results: At both sites, black clients are under-represented at treatment facilities. Private non-profit, outpatient facilities serve the highest proportion of black clients. Compared to private for-profit and state facilities, private non-profit facilities are the most likely to provide services that address the logistical, cultural and linguistic barriers that restrict black clients from accessing treatment. Outpatient facilities are more likely than inpatient facilities to address these barriers. Conclusions: Based on the above findings, a number of recommendations are made to improve the accessibility of treatment services for black clients, such as establishing state outpatient treatment facilities and addressing the indirect costs associated with treatment. Key Words: Alcohol, Public policy, Evidence-based intervention strategies South African Psychiatry Review Vol.8(1) 2005: 15-1

Interactive Supercomputing with MIT Matlab

This paper describes MITMatlab, a system that enables users of supercomputers or networked PCs to work on large data sets within Matlab transparently. MITMatlab is based on the Parallel Problems Server (PPServer), a standalone 'linear algebra server' that provides a mechanism for running distributed memory algorithms on large data sets. The PPServer and MITMatlab enable high-performance interactive supercomputing. With such a tool, researchers can now use Matlab as more than a prototyping tool for experimenting with small problems. Instead, MITMatlab makes is possible to visualize and operate interactively on large data sets. This has implications not only in supercomputing, but for Artificial Intelligence applicatons such as Machine Learning, Information Retrieval and Image Processing

Methamphetamine abuse, psychosis and your patient

Recent findings from the MRC-led South African Community Epidemiology Network on Drug Use (SACENDU) Project(which collects data on treatment episodes from substance abuse treatment centres) point to a significant and unprecedented increase in the proportion of clients reporting methamphetamine (MA) as their primary and/or secondary drug of abuse at these specialist substance abuse treatment centres in the Western Cape. For example, the proportion of clients reporting methamphetamine-related problems has increased from 5% of the total treatment population at Cape Town Drug Counselling Centre (the largest non-profit outpatient treatment centre in Cape Town) in 2003 to between 44% and 48% of the treatment population in 2004.1For full text, click here:SA Fam Pract 2006;48(2):56-5

CREWS : a Component-driven, Run-time Extensible Web Service framework

There has been an increased focus in recent years on the development of re-usable software, in the form of objects and software components. This increase, together with pressures from enterprises conducting transactions on the Web to support all business interactions on all scales, has encouraged research towards the development of easily reconfigurable and highly adaptable Web services. This work investigates the ability of Component-Based Software Development (CBSD) to produce such systems, and proposes a more manageable use of CBSD methodologies. Component-Driven Software Development (CDSD) is introduced to enable better component manageability. Current Web service technologies are also examined to determine their ability to support extensible Web services, and a dynamic Web service architecture is proposed. The work also describes the development of two proof-of-concept systems, DREW Chat and Hamilton Bank. DREW Chat and Hamilton Bank are implementations of Web services that support extension dynamically and at run-time. DREW Chat is implemented on the client side, where the user is given the ability to change the client as required. Hamilton Bank is a server-side implementation, which is run-time customisable by both the user and the party offering the service. In each case, a generic architecture is produced to support dynamic Web services. These architectures are combined to produce CREWS, a Component-driven Runtime Extensible Web Service solution that enables Web services to support the ever changing needs of enterprises. A discussion of similar work is presented, identifying the strengths and weaknesses of our architecture when compared to other solutions