Symmetric angular momentum coupling, the quantum volume operator and the 7-spin network: a computational perspective

A unified vision of the symmetric coupling of angular momenta and of the quantum mechanical volume operator is illustrated. The focus is on the quantum mechanical angular momentum theory of Wigner's 6j symbols and on the volume operator of the symmetric coupling in spin network approaches: here, crucial to our presentation are an appreciation of the role of the Racah sum rule and the simplification arising from the use of Regge symmetry. The projective geometry approach permits the introduction of a symmetric representation of a network of seven spins or angular momenta. Results of extensive computational investigations are summarized, presented and briefly discussed.Comment: 15 pages, 10 figures, presented at ICCSA 2014, 14th International Conference on Computational Science and Application

A Portrait of Quebec Baby Boomers who Use the Internet to Meet Men for Sexual Purposes Based on Data from the Quebec “Net Gay Baromètre” Study

International audienceObjective: The online survey, “Net Gay Baromètre”, provides a portrait of men visiting websites for gay men to meet and can help describe their sexuality with casual and regular partners and guide prevention activities accordingly. Respondents of the baby boomer generation are described here.Method: Men were recruited between January and April, 2008 (n = 3560), through personalized e-mailing on nine major websites that are representative of the socio-sexual diversity of the French MSM population. Baby boomers (1945 > 1964) account for 26.1 % of the sample (n = 928). Bivariate analyses (χ2, t tests) as well as simple and multiple logistic regression analyses were conducted.Results : Compared with younger men, baby boomers are more educated and have a higher income. More of these men self-define as bisexual, report having been the victim of insults, frequent the gay community less often, and use sex venues (saunas, cruising spaces, etc.). Fewer baby boomers are in a committed relationship, more are HIV-positive.They are also sexually active, reporting as many casual sex partners as younger men in the past twelve months. They are more often in non-monogamous relationships. They also take part in sex involving the exchange of money more frequently. However, boomers engage in less unprotected anal intercourse for all frequency levels and have less bareback sex and anal exposure to sperm.Multivariate analyses show that regular unprotected anal intercourse, which is practiced by 16.5% of this group (vs. 21.1% among younger men), is associated with self-identifying as homosexual, taking drugs at least once, frequenting a sex venue, having had more than ten casual partners in the previous twelve months, engaging in marginal sexual practices, and having had oral contact with sperm over the same period.Conclusion: Baby boomers are often overlooked as a group in behavioural surveys of men who have sex with men. Our findings suggest that they are less integrated into the gay community and live alone more often than younger groups. Even though they are less frequently involved in risky sexual practices, predictors of regular risk-taking in this group overlap with those of the global sample

Improved lower bounds for the ground-state energy of many-body systems

New lower bounds for the binding energy of a quantum-mechanical system of interacting particles are presented. The new bounds are expressed in terms of two-particle quantities and improve the conventional bounds of the Hall-Post type. They are constructed by considering not only the energy in the two-particle system, but also the structure of the pair wave function. We apply the formal results to various numerical examples, and show that in some cases dramatic improvement over the existing bounds is reached.Comment: 29 pages, 5 figures, to be published in Phys. Rev.

Comparing Psychological, Social, and Sexuality-Related Problems Reported by Bisexual and Gay Men: A Canadian Internet-Based Study

Les différences entre les hommes gais et les hommes bisexuels quant à leurs problématiques de santé méritent d\u27être mieux cernées. Dans le cadre d\u27une enquête en ligne pancanadienne, nous avons comparé des hommes bisexuels (n = 564) et gais (n = 1,109) à partir de 32 problèmes autoperçus d\u27ordre psychologique, social ou sexuel auxquels ils pouvaient avoir fait face au cours des 12 derniers mois. Les résultats indiquent que, par rapport aux hommes gais, les hommes bisexuels font face davantage aux problèmes touchant l\u27orientation ou l\u27identité sexuelle ou relatifs à certains comportements néfastes pour la santé, mais moins à plusieurs problèmes de santé mentale et à des problèmes liés aux ITS/VIH