Religious affiliation and extramarital sex among men in Brazil.

CONTEXT: Since 1990, HIV infection in Brazil has spread among the heterosexual population, particularly in the north. Containment of the epidemic can be informed by a better understanding of men's sexual risk behavior. METHODS: Logistic, Poisson and multilevel logit models were applied to data on married and cohabiting men who had participated in the 1996 Brazilian Demographic and Health Survey. RESULTS: Twelve percent of married or cohabiting men reported having had at least one extramarital partner in the previous 12 months; half of these had had two or more. The majority (77%) of partners were described as friends or lovers; 4% had been prostitutes and 15% strangers. Among men who had had sex with an extramarital partner in the last year, 40% reported having used condoms during last extramarital sex. Compared with members of evangelical religions, other men were significantly more likely to report having had an extramarital partner (odds ratios, 3.0-4.7) and unprotected extramarital sex in the last 12 months (3.4-7.9). Region of residence was also strongly correlated with extramarital sex: Compared with men in southern or central Brazil, those in the north had more than three times the odds of having had extramarital sex and unprotected extramarital sex in the last year (3.1-3.8). CONCLUSION: In Brazil, religious affiliation and region of residence exert a major influence on risk behavior

Quantification of efficiency improvements from integration of battery energy storage systems and renewable energy sources into domestic distribution networks

Due to the increasing use of renewable, non-controllable energy generation systems energy storage systems (ESS) are seen as a necessary part of future power delivery systems. ESS have gained research interest and practical implementation over the past decade and this is expected to continue into the future. This is due to the economic and operational benefits for both network operators and customers, battery energy storage system (BESS) is used as the main focus of this research paper. This paper presents an analytical study of the benefits of deploying distributed BESS in an electrical distribution network (DN). The work explores the optimum location of installing BESS and its impact on the DN performance and possible future investment. This study provides a comparison between bulk energy storage installed at three different locations; medium voltage (MV) side and low voltage (LV) side of the distribution transformer (DT) and distributed energy storage at customers’ feeders. The performance of a typical UK DN is examined under different penetration levels of wind energy generation units and BESS. The results show that the minimum storage size is obtained when BESS is installed next to the DT. However, the power loss is reduced to its minimum when BESS and wind energy are both distributed at load busbars. The study demonstrates that BESS installation has improved the loss of life factor of the distribution transformer

On the implications of a dilaton in gauge theory

Some recent work on the implications of a dilaton in 4d gauge theories are revisited. In part I of this paper we see how an effective dilaton coupling to gauge kinetic term provides a simple attractive mechanism to generate confinement. In particular, we put emphasis on the derivation of confining analytical solutions and look into the problem how dilaton degrees of freedom modify Coulom potential and when a confining phase occurs. In part II, we solve the semi-relativistic wave equation, for Dick interquark potential using the Shifted l-expansion technique (SLET) in the heavy quarkonium sector. The results of this phenomenological analysis proves that these effective theories can be relevant to model quark confinement and may shed some light on confinement mechanism.Comment: 8 pages. Talk given at CTP Symposium on Supersymmetry at LHC: Theoretical and Experimental Prospectives, Cairo, Egypt, 11-14 Mar 200

On the Efficient Calculation of a Linear Combination of Chi-Square Random Variables with an Application in Counting String Vacua

Linear combinations of chi square random variables occur in a wide range of fields. Unfortunately, a closed, analytic expression for the pdf is not yet known. As a first result of this work, an explicit analytic expression for the density of the sum of two gamma random variables is derived. Then a computationally efficient algorithm to numerically calculate the linear combination of chi square random variables is developed. An explicit expression for the error bound is obtained. The proposed technique is shown to be computationally efficient, i.e. only polynomial in growth in the number of terms compared to the exponential growth of most other methods. It provides a vast improvement in accuracy and shows only logarithmic growth in the required precision. In addition, it is applicable to a much greater number of terms and currently the only way of computing the distribution for hundreds of terms. As an application, the exponential dependence of the eigenvalue fluctuation probability of a random matrix model for 4d supergravity with N scalar fields is found to be of the asymptotic form exp(-0.35N).Comment: 21 pages, 19 figures. 3rd versio