45 research outputs found

    Gravitational radiation from gamma-ray bursts as observational opportunities for LIGO and VIRGO

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    Gamma-ray bursts are believed to originate in core-collapse of massive stars. This produces an active nucleus containing a rapidly rotating Kerr black hole surrounded by a uniformly magnetized torus represented by two counter-oriented current rings. We quantify black hole spin-interactions with the torus and charged particles along open magnetic flux-tubes subtended by the event horizon. A major output of Egw=4e53 erg is radiated in gravitational waves of frequency fgw=500 Hz by a quadrupole mass-moment in the torus. Consistent with GRB-SNe, we find (i) Ts=90s (tens of s, Kouveliotou et al. 1993), (ii) aspherical SNe of kinetic energy Esn=2e51 erg (2e51 erg in SN1998bw, Hoeflich et al. 1999) and (iii) GRB-energies Egamma=2e50 erg (3e50erg in Frail et al. 2001). GRB-SNe occur perhaps about once a year within D=100Mpc. Correlating LIGO/Virgo detectors enables searches for nearby events and their spectral closure density 6e-9 around 250Hz in the stochastic background radiation in gravitational waves. At current sensitivity, LIGO-Hanford may place an upper bound around 150MSolar in GRB030329. Detection of Egw thus provides a method for identifying Kerr black holes by calorimetry.Comment: to appear in PRD, 49

    Two randomised and placebo-controlled studies of an oral prostacyclin analogue (Iloprost) in severe leg ischaemia [The Oral Iloprost in severe Leg Ischaemia Study Group]

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    Two separate studies are described using the same prostacyclin analogue in a similar group of patients. Objectives: to assess the tolerability and efficacy of two dose regimens of oral Iloprost compared with placebo in the treatment of patients with ischaemic ulcers, gangrene or rest pain due to severe arterial disease over a period of 4 weeks (Study A) and one year (Study B). Design: multicentre, placebo controlled, double-blind, randomized prospective studies. Subjects & Methods: 178 (study A) and 624 (study B) patients with trophic skin lesions (ulcers or gangrene) or ischaemic rest pain due to severe arterial disease. To confirm severe arterial disease patients were required to have a systolic ankle Doppler pressure of 70 mmHg or less or a toe systolic Doppler pressure of 50 mmHg or less in one leg.In both studies patients were randomly allocated to three treatment groups: placebo, low dose Iloprost (50\u2013100 g twice a day) or high dose (150\u2013200 g twice a day) In Study A the main outcome measures were tolerability of different doses of Iloprost and death, major amputation, healing of trophic lesions and relief of rest pain at the end of the follow up, which was 5 months after the end of the treatment. In Study B the primary end point was time to major amputation and stroke or death up to 12 months. Secondary pre-defined end points included the combined end point of patients alive without amputation, no trophic skin changes, no rest pain and not on regular analgesics. Results: the proportion of patients who completed the 4-week treatment period in Study A at the intended dose was 58%, 43%, 45% respectively in the placebo, low dose and high dose Iloprost groups. In an intention to treat analysis the proportion of patients who survived without major amputation, ulcers or gangrene and had no rest pain was 11% in the placebo group, 19% in the low dose iloprost group and 28% in the high dose Iloprost group. The pooled Iloprost groups showed a statistically significantly better result than the placebo group (p=0.04), as did the high dose Iloprost group compared to the placebo (p=0.014). In Study B there was no treatment benefit in terms of a primary end point of amputation and death. However the secondary combined end point of patients who survived without a major amputation, ulcers or gangrene and had no rest pain, nor a need for regular analgesia was favourable for Iloprost, with 18% of patients in the placebo group reaching this optimal secondary end point, compared to 23% in the low dose Iloprost group and 26% in the higher dose Iloprost group (p<0.05). Conclusions: oral Iloprost administered for a year showed no clear benefit in patients with advanced severe leg ischaemia (PAOD III and IV). The results obtained with 4 weeks\u2019 treatment in Study A and in previous trials of intravenous Iloprost could not be reproduce

    A História da Alimentação: balizas historiogråficas

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    Os M. pretenderam traçar um quadro da HistĂłria da Alimentação, nĂŁo como um novo ramo epistemolĂłgico da disciplina, mas como um campo em desenvolvimento de prĂĄticas e atividades especializadas, incluindo pesquisa, formação, publicaçÔes, associaçÔes, encontros acadĂȘmicos, etc. Um breve relato das condiçÔes em que tal campo se assentou faz-se preceder de um panorama dos estudos de alimentação e temas correia tos, em geral, segundo cinco abardagens Ia biolĂłgica, a econĂŽmica, a social, a cultural e a filosĂłfica!, assim como da identificação das contribuiçÔes mais relevantes da Antropologia, Arqueologia, Sociologia e Geografia. A fim de comentar a multiforme e volumosa bibliografia histĂłrica, foi ela organizada segundo critĂ©rios morfolĂłgicos. A seguir, alguns tĂłpicos importantes mereceram tratamento Ă  parte: a fome, o alimento e o domĂ­nio religioso, as descobertas europĂ©ias e a difusĂŁo mundial de alimentos, gosto e gastronomia. O artigo se encerra com um rĂĄpido balanço crĂ­tico da historiografia brasileira sobre o tema

    Radiotherapy for Prostate Cancer: is it ‘what you do’ or ‘the way that you do it’? A UK Perspective on Technique and Quality Assurance

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    Laboratory evaluation of a SpectraMax microplate reader and test strips for field measurement of creatinine in spot urine samples in the event of a radiological accident

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    The fear that terrorists might use radiological or nuclear (RN) devices to attack others is a new but growing phenomenon, arising mainly from the events of 11 September 2001. Research on rapid analytical methods that can allow analyses of large numbers of people who may become internally contaminated with radionuclides due to a RN accident is still limited. To contribute to this bioassay capacity for emergency response, the Radiation Protection Bureau of Health Canada has identified and evaluated two new portable SpectraMax plate readers (model 250 and Plus 384) and one brand of dry reagent strips for rapid measurement of creatinine in spot urine samples. Concentrations of creatinine in spot urine samples provide a means of adjusting or normalizing urine collections to 24 h, upon which accurate internal dose assessments due to the radionuclides can be made. Preliminary test results of the devices showed the two SpectraMax plate readers and the TECO dry creatinine reagent strips were portable, rapid and reliable for urinary creatinine measurements in spot samples, suggesting they can be used in rapid dose screening of people
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