39 research outputs found

    Excitation and decay of projectile-like fragments formed in dissipative peripheral collisions at intermediate energies

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    Projectile-like fragments (PLF:15<=Z<=46) formed in peripheral and mid-peripheral collisions of 114Cd projectiles with 92Mo nuclei at E/A=50 MeV have been detected at very forward angles, 2.1 deg.<=theta_lab<=4.2 deg. Calorimetric analysis of the charged particles observed in coincidence with the PLF reveals that the excitation of the primary PLF is strongly related to its velocity damping. Furthermore, for a given V_PLF*, its excitation is not related to its size, Z_PLF*. For the largest velocity damping, the excitation energy attained is large, approximately commensurate with a system at the limiting temperatureComment: 5 pages, 6 figure

    Fragmentation in Peripheral Heavy-Ion Collisions: from Neck Emission to Spectator Decays

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    Invariant cross sections of intermediate mass fragments in peripheral collisions of Au on Au at incident energies between 40 and 150 AMeV have been measured with the 4-pi multi-detector INDRA. The maximum of the fragment production is located near mid-rapidity at the lower energies and moves gradually towards the projectile and target rapidities as the energy is increased. Schematic calculations within an extended Goldhaber model suggest that the observed cross-section distributions and their evolution with energy are predominantly the result of the clustering requirement for the emerging fragments and of their Coulomb repulsion from the projectile and target residues. The quantitative comparison with transverse energy spectra and fragment charge distributions emphasizes the role of hard scattered nucleons in the fragmentation process.Comment: 5 pages, 5 eps figures, RevTeX4, submitted to Phys. Lett.

    Using the past to constrain the future: how the palaeorecord can improve estimates of global warming

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    Climate sensitivity is defined as the change in global mean equilibrium temperature after a doubling of atmospheric CO2 concentration and provides a simple measure of global warming. An early estimate of climate sensitivity, 1.5-4.5{\deg}C, has changed little subsequently, including the latest assessment by the Intergovernmental Panel on Climate Change. The persistence of such large uncertainties in this simple measure casts doubt on our understanding of the mechanisms of climate change and our ability to predict the response of the climate system to future perturbations. This has motivated continued attempts to constrain the range with climate data, alone or in conjunction with models. The majority of studies use data from the instrumental period (post-1850) but recent work has made use of information about the large climate changes experienced in the geological past. In this review, we first outline approaches that estimate climate sensitivity using instrumental climate observations and then summarise attempts to use the record of climate change on geological timescales. We examine the limitations of these studies and suggest ways in which the power of the palaeoclimate record could be better used to reduce uncertainties in our predictions of climate sensitivity.Comment: The final, definitive version of this paper has been published in Progress in Physical Geography, 31(5), 2007 by SAGE Publications Ltd, All rights reserved. \c{opyright} 2007 Edwards, Crucifix and Harriso

    Advances and challenges in the management of complement-mediated thrombotic microangiopathies

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    Item does not contain fulltextComplement activation plays a major role in several renal pathophysiological conditions. The three pathways of complement lead to C3 activation, followed by the formation of the anaphylatoxin C5a and the terminal membrane attack complex (MAC) in blood and at complement activating surfaces, lead to a cascade of events responsible for inflammation and for the induction of cell lysis. In case of ongoing uncontrolled complement activation, endothelial cells activation takes place, leading to events in which at the end thrombotic microangiopathy can occur. Atypical haemolytic uremic syndrome (aHUS) is a thrombotic microangiopathy characterized by excessive complement activation on the surface of the microcirculation. It is a severe, rare disease which leads to end-stage renal failure (ESRF) and/or to death in more than 50% of patients without treatment. In the first decade of the second millennium, huge progress in understanding the aetiology of this disease was made, which paved the way to better treatment. First, protocols of plasma therapy for treatment, prevention of relapses and for renal transplantation in those patients were set up. Secondly, in some severe cases, combined kidney and liver transplantation was reported. Finally, at the end of this decade, the era of complement inhibitors, as anti-C5 monoclonal antibody (anti-C5 mAb) began. The past five years have seen growing evidence of the favourable effect of anti-C5 mAb in aHUS which has made this drug the first-line treatment in this disease. The possible complication of meningococcal infection needs appropriate vaccination before its use. Unfortunately, the worldwide use of anti-C5 mAb is limited by its very high price. In the future, extension of indications for anti-C5 mAb use, the elaboration of generics and of mAbs directed towards other complement factors of the terminal pathway of the complement system might succeed in reducing the cost of this new valuable therapeutic approach and render it available worldwide for patients from all social classes

    A Case of Congenital Nephrotic Syndrome

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    Cardiovascular disease as a late complication of end-stage renal disease in children.

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    Item does not contain fulltextAs in older adults, cardiovascular disease is the most important cause of death in adolescents and young adult patients with end-stage renal disease (ESRD) since childhood. This concerns patients on dialysis as well as transplant patients, despite the fact that a long duration of dialysis during childhood is an extra mortality risk factor. Left ventricular hypertrophy (LVH), aortic valve calcification, and increased arterial stiffness, but not increased arterial intima media thickening, are the most frequently observed alterations in young adult survivors with childhood ESRD. In transplanted patients a concentric LVH as a result of chronic hypertension is mostly observed; in dialysis patients a more asymmetric septal LVH is found as a result of chronic volume overload. These results suggest that in children and young adults with ESRD chronic pressure and volume overload, a high calcium-phosphate product, and chronic inflammation, but not dyslipidemia, play a role in the development of cardiovascular disease
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