4 research outputs found
Exploration of the Transition from the Hydrodynamiclike to the Strongly Kinetic Regime in Shock-Driven Implosions
Clear evidence of the transition from hydrodynamiclike to strongly kinetic shock-driven implosions is, for the first time, revealed and quantitatively assessed. Implosions with a range of initial equimolar D[superscript 3]He gas densities show that as the density is decreased, hydrodynamic simulations strongly diverge from and increasingly overpredict the observed nuclear yields, from a factor of âŒ2 at 3.1ââmg/cm[superscript 3] to a factor of 100 at 0.14ââmg/cm[superscript 3]. (The corresponding Knudsen number, the ratio of ion mean-free path to minimum shell radius, varied from 0.3 to 9; similarly, the ratio of fusion burn duration to ion diffusion time, another figure of merit of kinetic effects, varied from 0.3 to 14.) This result is shown to be unrelated to the effects of hydrodynamic mix. As a first step to garner insight into this transition, a reduced ion kinetic (RIK) model that includes gradient-diffusion and loss-term approximations to several transport processes was implemented within the framework of a one-dimensional radiation-transport code. After empirical calibration, the RIK simulations reproduce the observed yield trends, largely as a result of ion diffusion and the depletion of the reacting tail ions.United States. Dept. of Energy (Grant DE-NA0001857)United States. Dept. of Energy (Grant DE-FC52-08NA28752)University of Rochester. Fusion Science Center (5-24431)National Laser Userâs Facility (DE-NA0002035)University of Rochester. Laboratory for Laser Energetics (415935-G)Lawrence Livermore National Laboratory (B597367
Observations of Multiple Nuclear Reaction Histories and Fuel-Ion Species Dynamics in Shock-Driven Inertial Confinement Fusion Implosions
Fuel-ion species dynamics in hydrodynamiclike shock-driven DTÂłHe-filled inertial confinement fusion implosion is quantitatively assessed for the first time using simultaneously measured DÂłHe and DT reaction histories. These reaction histories are measured with the particle x-ray temporal diagnostic, which captures the relative timing between different nuclear burns with unprecedented precision (âŒ10ââps). The observed 50±10ââps earlier DÂłHe reaction history timing (relative to DT) cannot be explained by average-ion hydrodynamic simulations and is attributed to fuel-ion species separation between the D, T, and ÂłHe ions during shock convergence and rebound. At the onset of the shock burn, inferred ÂłHe/T fuel ratio in the burn region using the measured reaction histories is much higher as compared to the initial gas-filled ratio. As T and ÂłHe have the same mass but different charge, these results indicate that the charge-to-mass ratio plays an important role in driving fuel-ion species separation during strong shock propagation even for these hydrodynamiclike plasmas.United States. Department of Energy (Grant DE-FC52-08NA28752
Enhanced infection prophylaxis reduces mortality in severely immunosuppressed HIV-infected adults and older children initiating antiretroviral therapy in Kenya, Malawi, Uganda and Zimbabwe: the REALITY trial
Meeting abstract FRAB0101LB from 21st International AIDS Conference 18â22 July 2016, Durban, South Africa.
Introduction: Mortality from infections is high in the first 6 months of antiretroviral therapy (ART) among HIVâinfected adults and children with advanced disease in subâSaharan Africa. Whether an enhanced package of infection prophylaxis at ART initiation would reduce mortality is unknown.
Methods:
The REALITY 2Ă2Ă2 factorial openâlabel trial (ISRCTN43622374) randomized ARTânaĂŻve HIVâinfected adults and children >5 years with CD4 <100 cells/mm3. This randomization compared initiating ART with enhanced prophylaxis (continuous cotrimoxazole plus 12 weeks isoniazid/pyridoxine (antiâtuberculosis) and fluconazole (antiâcryptococcal/candida), 5 days azithromycin (antiâbacterial/protozoal) and singleâdose albendazole (antiâhelminth)), versus standardâofâcare cotrimoxazole. Isoniazid/pyridoxine/cotrimoxazole was formulated as a scored fixedâdose combination. Two other randomizations investigated 12âweek adjunctive raltegravir or supplementary food. The primary endpoint was 24âweek mortality.
Results:
1805 eligible adults (n = 1733; 96.0%) and children/adolescents (n = 72; 4.0%) (median 36 years; 53.2% male) were randomized to enhanced (n = 906) or standard prophylaxis (n = 899) and followed for 48 weeks (3.8% lossâtoâfollowâup). Median baseline CD4 was 36 cells/mm3 (IQR: 16â62) but 47.3% were WHO Stage 1/2. 80 (8.9%) enhanced versus 108(12.2%) standard prophylaxis died before 24 weeks (adjusted hazard ratio (aHR) = 0.73 (95% CI: 0.54â0.97) p = 0.03; Figure 1) and 98(11.0%) versus 127(14.4%) respectively died before 48 weeks (aHR = 0.75 (0.58â0.98) p = 0.04), with no evidence of interaction with the two other randomizations (p > 0.8). Enhanced prophylaxis significantly reduced incidence of tuberculosis (p = 0.02), cryptococcal disease (p = 0.01), oral/oesophageal candidiasis (p = 0.02), deaths of unknown cause (p = 0.02) and (marginally) hospitalisations (p = 0.06) but not presumed severe bacterial infections (p = 0.38). Serious and grade 4 adverse events were marginally less common with enhanced prophylaxis (p = 0.06). CD4 increases and VL suppression were similar between groups (p > 0.2).
Conclusions:
Enhanced infection prophylaxis at ART initiation reduces early mortality by 25% among HIVâinfected adults and children with advanced disease. The pill burden did not adversely affect VL suppression. Policy makers should consider adopting and implementing this lowâcost broad infection prevention package which could save 3.3 lives for every 100 individuals treated