8,426 research outputs found

    Fermi pulsar revolution

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    2009 has been an extraordinary year for gamma-ray pulsar astronomy and 2010 promises to be equally good. Not only have we registered an extraordinary increase in the number of pulsars detected in gamma rays, but we have also witnessed the birth of new sub-families: first of all, the radio-quiet gamma pulsars and later an ever growing number of millisecond pulsars, a real surprise. We started with a sample of 7 gamma-ray emitting neutron stars (6 radio pulsars and Geminga) and now the Fermi-LAT harvest encompasses 24 "Geminga-like" new gamma-ray pulsars, a dozen millisecond pulsars and about thirty radio pulsars. Moreover, radio searches targeted to LAT unidentified sources yielded 18 new radio millisecond pulsars, several of which have been already detected also in gamma rays. Thus, currently the family of gamma-ray emitting neutron stars seems to be evenly divided between classical radio pulsars, millisecond pulsars and radio quiet neutron stars.Comment: High Time Resolution Astrophysics IV - The Era of Extremely Large Telescopes-HTRA-IV Agios Nikolaos, Crete, Greece May 5-7 2010 to be published in Po

    Timing for treatment of HCV recurrence after liver transplantation: the earlier the better.

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    HCV is the leading cause of death from liver disease and is the most common indication for a liver transplantation. Although HCV is a widespread health problem, disease management is particularly challenging in several key subpopulations, including liver transplant recipients. HCV recurrence after liver transplantation constituted a major challenge for the physicians during the last years. The recommended standard of care before the advent of new regimen was the treatment of confirmed recurrent disease, based either on persistent, unexplained elevated alanine aminotransferase levels or on histologically confirmed fibrosis, once rejection, biliary obstruction, and vascular damage have been ruled out. Moreover, early therapy (including interferon) has been associated with high rates of adverse effects, an increased risk of graft rejection, and higher proportions of patients requiring dose reductions. We are now facing a "new era" of direct antiviral agents that is already changing the approach to HCV burden in the post liver transplantation setting. Available data on treatment of HCV recurrence with the new antiviral drugs showed sustained virological response that ranges between 60 to 100%. In this comment we have focused on both the utility of non invasive test to evaluate the fibrosis progression and on timing of antiviral therapy for HCV recurrence. This article is protected by copyright. All rights reserved

    The Gribov problem in Noncommutative QED

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    It is shown that in the noncommutative version of QED (NCQED) Gribov copies induced by the noncommutativity of space-time appear in the Landau gauge. This is a genuine effect of noncommutative geometry which disappears when the noncommutative parameter vanishes.Comment: 19 pages, 3 figures. Published. The paper has been shortened and many references have been judged unnecessary or not suitable during the reviewing proces
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