Unraveling resistive versus collisional contributions to relativistic electron beam stopping power in cold-solid and in warm-dense plasmas

We present results on laser-driven relativistic electron beam propagation through aluminum samples, which are either solid and cold or compressed and heated by laser-induced shock. A full numerical description of fast electron generation and transport is found to reproduce the experimental absolute Kα yield and spot size measurements for varying target thicknesses, and to sequentially quantify the collisional and resistive electron stopping powers. The results demonstrate that both stopping mechanisms are enhanced in compressed Al samples and are attributed to the increase in the medium density and resistivity, respectively. For the achieved time- and space-averaged electronic current density, ⟨jh⟩∼8×1010 A/cm2 in the samples, the collisional and resistive stopping powers in warm and compressed Al are estimated to be 1.5 keV/μm and 0.8 keV/μm , respectively. By contrast, for cold and solid Al, the corresponding estimated values are 1.1 keV/μm and 0.6 keV/μm . Prospective numerical simulations involving higher jh show that the resistive stopping power can reach the same level as the collisional one. In addition to the effects of compression, the effect of the transient behavior of the resistivity of Al during relativistic electron beam transport becomes progressively more dominant, and for a significantly high current density, jh∼1012 A/cm2 , cancels the difference in the electron resistive stopping power (or the total stopping power in units of areal density) between solid and compressed samples. Analytical calculations extend the analysis up to jh=1014 A/cm2 (representative of the full-scale fast ignition scenario of inertial confinement fusion), where a very rapid transition to the Spitzer resistivity regime saturates the resistive stopping power, averaged over the electron beam duration, to values of ∼1 keV/μm

Early IL-1 receptor blockade in severe inflammatory respiratory failure complicating COVID-19

Contains fulltext : 229588.pdf (Publisher’s version ) (Open Access)Around the tenth day after diagnosis, ∼20% of patients with coronavirus disease 2019 (COVID-19)-associated pneumonia evolve toward severe oxygen dependence (stage 2b) and acute respiratory distress syndrome (stage 3) associated with systemic inflammation often termed a "cytokine storm." Because interleukin-1 (IL-1) blocks the production of IL-6 and other proinflammatory cytokines, we treated COVID-19 patients early in the disease with the IL-1 receptor antagonist, anakinra. We retrospectively compared 22 patients from three different centers in France with stages 2b and 3 COVID-19-associated pneumonia presenting with acute severe respiratory failure and systemic inflammation who received either standard-of-care treatment alone (10 patients) or combined with intravenous anakinra (12 patients). Treatment started at 300 mg⋅d(-1) for 5 d, then tapered with lower dosing over 3 d. Both populations were comparable for age, comorbidities, clinical stage, and elevated biomarkers of systemic inflammation. All of the patients treated with anakinra improved clinically (P < 0.01), with no deaths, significant decreases in oxygen requirements (P < 0.05), and more days without invasive mechanical ventilation (P < 0.06), compared with the control group. The effect of anakinra was rapid, as judged by significant decrease of fever and C-reactive protein at day 3. A mean total dose of 1,950 mg was infused with no adverse side effects or bacterial infection. We conclude that early blockade of the IL-1 receptor is therapeutic in acute hyperinflammatory respiratory failure in COVID-19 patients

High incidence of CDA deficiency in patients with hematological malignancies: perspectives and therapeutic implications

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Endothelium structure and function in kidney health and disease

The kidney harbours different types of endothelia, each with specific structural and functional characteristics. The glomerular endothelium, which is highly fenestrated and covered by a rich glycocalyx, participates in the sieving properties of the glomerular filtration barrier and in the maintenance of podocyte structure. The microvascular endothelium in peritubular capillaries, which is also fenestrated, transports reabsorbed components and participates in epithelial cell function. The endothelium of large and small vessels supports the renal vasculature. These renal endothelia are protected by regulators of thrombosis, inflammation and complement, but endothelial injury (for example, induced by toxins, antibodies, immune cells or inflammatory cytokines) or defects in factors that provide endothelial protection (for example, regulators of complement or angiogenesis) can lead to acute or chronic renal injury. Moreover, renal endothelial cells can transition towards a mesenchymal phenotype, favouring renal fibrosis and the development of chronic kidney disease. Thus, the renal endothelium is both a target and a driver of kidney and systemic cardiovascular complications. Emerging therapeutic strategies that target the renal endothelium may lead to improved outcomes for both rare and common renal diseases

Relativistic High-Current Electron-Beam Stopping-Power Characterization in Solids and Plasmas: Collisional Versus Resistive Effects

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Relativistic high-current electron-beam stopping-power characterization in solids and plasmas : collisional versus resistive effects

We present experimental and numerical results on intense-laser-pulse-produced fast electron beams transport through aluminum samples, either solid or compressed and heated by laser-induced planar shock propagation. Thanks to absolute K-alpha yield measurements and its very good agreement with results from numerical simulations, we quantify the collisional and resistive fast electron stopping powers: for electron current densities of approximate to 8 x 10(10) A/cm(2) they reach 1.5 keV/mu m and 0.8 keV/mu m, respectively. For higher current densities up to 10(12) A/cm(2), numerical simulations show resistive and collisional energy losses at comparable levels. Analytical estimations predict the resistive stopping power will be kept on the level of 1 keV/mu m for electron current densities of 10(14) A/cm(2), representative of the full-scale conditions in the fast ignition of inertially confined fusion targets

Experimental study of fast electron propagation in compressed matter

We report on experimental results of the fast electron transport in compressed plasmas, created by laser-induced shock propagation in both cylindrical and planar geometry. Two experiments were carried out. The first one was based on the compression of a polyimide cylinder filled with foams of three different initial densities (rho(0)). X-ray and proton radiographies of the target during the compression coupled with hydrodynamic simulations show that the obtained core densities and temperatures range from 2 to 11 g/cm(3) and from 30 to 120 eV, respectively. By studying the K-shell fluorescence from dopant atoms inside the target and from tracer layers situated at both front and rear side of the target it has been possible to investigate the fast electron propagation. The results show that Cu K-alpha yield emitted by the target rear side foil decreases with increasing compression, independently of rho(0). An electron collimation can also be observed for certain experimental conditions where a convergent resistivity gradient interacts with the fast electron beam. The second experiment was performed in a planar geometry with a compressing shock counter-propagative to the fast electron beam. In this case the areal density rho z seen by the electrons is constant during the compression in such a way that changes in the fast electron range should be ascribed to collective mechanisms. The study of the K-alpha fluorescence, from buried fluorescent layers of different atomic numbers, shows that the electrons with energy <75 key are more affected by resistive losses in compressed compared to non-compressed targets. These two experiments were part of the Experimental Fusion Validation Program of the HiPER project