Updated Measurement of the b baryon lifetime

sing about 4 million hadronic Z decays recorded with the Aleph detector, the lifetime of the b baryons has been measured using two independent data samples. From a maximum likelihood fit to the impact parameter distribution of leptons in 1085 Lambda-lepton combinations containing a b baryon sample of 719 decays the measured b baryon lifetime is \tau = 1.18 \pm 0.08(stat) \pm 0.07 (syst) ps The lifetime of the Lambda_b baryon from a maximum likelihood fit to the proper time distribution of 193 Lambda_c-lepton candidates is \tau_{\Lambda_b} = 1.21^{+0.13}_{-0.12}{stat}) \pm 0.04 {syst} ps. The combined result of the two measurements yields an averaged value \tau_{\Lambda_b} = 1.19 \pm{0.0

Mother-to-child transmission of HIV and its prevention: awareness and knowledge in Uganda and Tanzania

Awareness and knowledge about HIV mother-to-child transmission (MTCT) and preventive measures in different population groups and health personnel were analysed in future intervention areas in western Uganda and southwestern Tanzania. In Uganda, a total of 751 persons (440 clients of antenatal and outpatient clinics, 43 health workers, 239 villagers, 29 traditional birth attendants) and in Tanzania, 574 persons (410 clients, 49 health workers, 93 villagers, 18 traditional birth attendants) were interviewed.When given options, knowledge on transmission during pregnancy and delivery in women was 93% and 67% in Uganda and Tanzania respectively, and 86% and 78% for transmission during breastfeeding. In Uganda 59% of male interviewees did not believe that HIV is transmitted during breastfeeding. Expressed acceptance of HIV testing was above 90% in men and women in both countries, but only 10% of the clients in Uganda and 14% in Tanzania had been tested for HIV infection. Health workers´ knowledge regarding MTCT was acceptable, while traditional birth attendants´ knowledge on both MTCT and preventive measures was extremely poor. Recommendations on infant feeding were not compatible with WHO recommendations for HIV-infected women. If prevention of MTCT (PMTCT) interventions are to be accepted by the population and promoted by health personnel, thorough orientation and training are mandatory. Key Words:PMTCT, HIV, awareness, knowledge, western Uganda, western TanzaniaRÉSUMÉLa prise de conscience et la connaissance de la transmission mère-enfant du VIH (MTCT) et les mesures préventives parmi les différents groupes de la population et le personnel de santé ont été analysées dans des régions de l\'ouest de l\'Ouganda et le sud-ouest de la Tanzanie où les interventions auront lieu dans l\'avenir. En Ouganda, 751 personnes en tout (440 clients de centres médicaux prénatals et de services de consultation, 43 ouvriers de santé, 239 villageois, 29 préposés traditionnels de naissance) et en Tanzanie, 574 personnes (410 clients, 49 ouvriers de santé, 93 villageois et 18 préposés traditionnels de naissance) furent objet des entretiens. Lorsqu\'on leur a donné des options au choix, la connaissance de la transmission pendant la grossesse et à la naissance chez les femmes était de 93% et 67% en Ouganda et en Tanzanie respectivement et de 86% et 78% pour la transmission à l\'allaitement. En Ouganda, 59% des hommes interviewés ont eu du mal à croire que le virus peut être communiqué à l\'enfant lors de l\'allaitement. Plus de 90% des hommes et des femmes dans les deux pays ont exprimé une acceptation de dépistage du VIH. Cependant, seulement 10% de clients en Ouganda et 14% en Tanzanie ont fait le dépistage. La connaissance des ouvriers de santé concernant le MTCT était acceptable, tandis que la connaissance du MTCT et les mesures préventives chez les préposés traditionnels de naissance fut extrêmement faible. Les recommandations de l\'allaitement de l\'enfant n\'étaient pas compatibles avec les recommandations de l\'OMS pour des femmes infectées. Afin que les interventions PMTCT soient acceptées par la population et promues par le personnel de santé, une orientation et une formation approfondies sont obligatoires. Mots clés: PMTCT,VIH, prise de conscience, connaissance, l\'ouest de l\'Ouganda, l\'ouest de la Tanzanie. Journal of Social Aspects of HIV/AIDS Vol 2(2) 2005:258-26

The dissociation of (a+c) misfit dislocations at the InGaN/GaN interface

(a+c) dislocations in hexagonal materials are typically observed to be dissociated into partial dislocations. Edge (a+c) dislocations are introduced into (0001) nitride semiconductor layers by the process of plastic relaxation. As there is an increasing interest in obtaining relaxed InGaN buffer layers for the deposition of high In content structures, the study of the dissociation mechanism of misfit (a+c) dislocations laying at the InGaN/GaN interface is then crucial for understanding their nucleation and glide mechanisms. In the case of the presented plastically relaxed InGaN layers deposited on GaN substrates we observe a trigonal network of (a+c) dislocations extending at the interface with a rotation of 3 degrees from directions. High resolution microscopy studies show that these dislocations are dissociated into two Frank-Shockley 1/6 partial dislocations with the I1 BSF spreading between them. Atomistic simulations of a dissociated edge (a+c) dislocation revealed a 3/5 atom ring structure for the cores of both partial dislocations. The observed separation between two partial dislocations must result from the climb of at least one of the dislocations during the dissociation process, possibly induced by the mismatch stress in the InGaN layer.Comment: This is a submitted version of the manuscript published in Journal of Microscop

RooStatsCms: a tool for analyses modelling, combination and statistical studies

The RooStatsCms (RSC) software framework allows analysis modelling and combination, statistical studies together with the access to sophisticated graphics routines for results visualisation. The goal of the project is to complement the existing analyses by means of their combination and accurate statistical studies.Comment: Proceedings of the 11th Topical Seminar on Innovative Particle and Radiation Detectors. 4 pages and 5 figure

Wide-Field Landers Temporary Keratoprosthesis in Severe Ocular Trauma: Functional and Anatomical Results after One Year

Purpose. To evaluate longitudinal functional and anatomical results after combined pars plana vitrectomy (PPV) and penetrating keratoplasty (PKP) using a wide-field Landers intraoperative temporary keratoprosthesis (TKP) in patients with vitreoretinal pathology and corneal opacity due to severe ocular trauma. Material and Methods. Medical records of 12 patients who had undergone PPV/PKP/KP due to severe eye trauma were analyzed. Functional (best-corrected visual acuity) and anatomic outcomes (clarity of the corneal graft, retinal attachment, and intraocular pressure) were assessed during the follow-up (mean 16 months). Results. Final visual acuities varied from NLP to CF to 2 m. Visual acuity improved in 7 cases, was unchanged in 4 eyes, and worsened in 1 eye. The corneal graft was transparent during the follow-up in 3 cases and graft failure was observed in 9 eyes. Silicone oil was used as a tamponade in all cases and retina was reattached in 92% of cases. Conclusions. Combined PPV and PKP with the use of wide-field Landers TKP allowed for surgical intervention in patients with vitreoretinal pathology coexisting with corneal wound. Although retina was attached in most of the cases, corneal graft survived only in one-fourth of patients and final visual acuities were poor