Formation of wind-captured discs in Supergiant X-ray binaries : consequences for Vela X-1 and Cygnus X-1

In Supergiant X-ray binaries (SgXB), a compact object captures a fraction of the wind of an O/B supergiant on a close orbit. Proxies exist to evaluate the efficiency of mass and angular momentum accretion but they depend so dramatically on the wind speed that given the current uncertainties, they only set loose constrains. Furthermore, they often bypass the impact of orbital and shock effects on the flow structure. We study the wind dynamics and the angular momentum gained as the flow is accreted. We identify the conditions for the formation of a disc-like structure around the accretor and the observational consequences for SgXB. We use recent results on the wind launching mechanism to compute 3D streamlines, accounting for the gravitational and X-ray ionizing influence of the compact companion on the wind. Once the flow enters the Roche lobe of the accretor, we solve the hydrodynamics equations with cooling. A shocked region forms around the accretor as the flow is beamed. For wind speeds of the order of the orbital speed, the shock is highly asymmetric compared to the axisymmetric bow shock obtained for a purely planar homogeneous flow. With net radiative cooling, the flow always circularizes for wind speeds low enough. Although the donor star does not fill its Roche lobe, the wind can be significantly beamed and bent by the orbital effects. The net angular momentum of the accreted flow is then sufficient to form a persistent disc-like structure. This mechanism could explain the proposed limited outer extension of the accretion disc in Cygnus X-1 and suggests the presence of a disc at the outer rim of the neutron star magnetosphere in Vela X-1, with dramatic consequences on the spinning up of the accretor

A gobal fit to the anomalous magnetic moment, Higgs limit and b->s gamma in the constrained MSSM

New data on the anomalous magnetic moment of the muon together with the b->s gamma decay rate and Higgs limits are considered within the supergravity inspired constrained minimal supersymmetric model. We perform a global statistical chi2 analysis of these data and show that the allowed region of parameter space is bounded from below by the Higgs limit, which depends on the trilinear coupling and from above by the anomalous magnetic moment.Comment: 3 pages, To appear in Proc. of SUSY01, Dubna (Russia

The harmonic measure of diffusion-limited aggregates including rare events

We obtain the harmonic measure of diffusion-limited aggregate (DLA) clusters using a biased random-walk sampling technique which allows us to measure probabilities of random walkers hitting sections of clusters with unprecedented accuracy; our results include probabilities as small as 10- 80. We find the multifractal D(q) spectrum including regions of small and negative q. Our algorithm allows us to obtain the harmonic measure for clusters more than an order of magnitude larger than those achieved using the method of iterative conformal maps, which is the previous best method. We find a phase transition in the singularity spectrum f(α) at α≈14 and also find a minimum q of D(q), qmin=0.9±0.05

Traditional practices and perceptions of epilepsy among people in Roma communities in Bulgaria

PURPOSE: We attempted to identify cultural aspects of epilepsy among the Roma community in Bulgaria by elucidating cultural beliefs, traditional treatments, and potential markers of stigma. METHODS: We established representative discussion groups among five distinct Roma subgroups (Lom, Kalderas, Thracian Tinsmiths (Tinkers), Kyustendil Xoroxane and Kopanari) from different Bulgarian regions. Data about local beliefs and treatment strategies were gathered. RESULTS: Most people were familiar with convulsions but non-convulsive focal seizures were seen not as epileptic but mainly as a "mental problem". Beliefs about putative etiologies for epilepsy were not uniform as some considered environmental and external factors such as high environmental temperatures, electric shocks, loud music, and fever as causes of seizures while others listed bad experiences, stress, trauma, and fear as possible causes. Epilepsy was seen by some as a divine punishment or resulting from black magic. Most considered epilepsy shameful and an obstacle to children attending school. Despite local differences, there was a uniform belief that epilepsy is incurable by Western medicine and people usually resort to traditional healers. A variety of rituals performed by local healers to treat epilepsy were described. DISCUSSION: Misconceptions about epilepsy may contribute to stigmatization in this population; this may in turn contribute to a high treatment gap in this group. As a result, the majority of Roma children with epilepsy are likely to leave school early, are greatly limited in their choice of spouse (particularly girls), and marriages often occur between people with epilepsy or those with a family history of epilepsy