Hollow cathode plasma penetration study Final report

Hollow cathode electron beam discharge for penetrating plasma sheath around reentry vehicl

Accelerated soil carbon loss does not explain warming related increases in soil CO2 efflux

The universally observed exponential increase in soil-surface CO2 efflux (‘soil respiration’; FS) with increasing temperature has led to speculation that global warming will accelerate soil-organic-carbon (SOC) decomposition, reduce SOC storage, and drive a positive feedback to future warming. However, interpreting temperature–FS relationships, and so modelling terrestrial carbon balance in a warmer world, is complicated by the many sources of respired carbon that contribute to FS (ref. 3) and a poor understanding of how temperature influences SOC decomposition rates. Here we quantified FS, litterfall, bulk SOC and SOC fraction size and turnover, and total below-ground carbon flux (TBCF) across a highly constrained 5.2 °C mean annual temperature (MAT) gradient in tropical montane wet forest. From these, we determined that: increases in TBCF and litterfall explain >90% of the increase in FS with MAT; bulk SOC and SOC fraction size and turnover rate do not vary with MAT; and increases in TBCF and litterfall do not influence SOC storage or turnover on century to millennial timescales. This gradient study shows that for tropical montane wet forest, long-term and whole-ecosystem warming accelerates below-ground carbon processes with no apparent impact on SOC storage

The Promise of Catholic Schools for Educating the Future of Los Angeles

This study examined the impact of Catholic education on elementary and secondary students in Los Angeles. The study focused on the continuation and graduation rates of ethnic minority students who received special funding from the Catholic Education Foundation (CEF). Using qualitative and quantitative measures, the study revealed that students from ethnic minority and low-income communities enrolled in Catholic schools are graduating from secondary schools at a higher rate than their peers who are enrolled in public schools. Furthermore, survey data was collected from principals and parents of these students enrolled in Catholic schools. The study shows that a Catholic education has a major impact on the lives of these students, their parents, and their communities

Improving Mean Time Between Pump Failures

Discussion Grou

Leaf litter decomposition rates increase with rising mean annual temperature in Hawaiian tropical montane wet forests

Decomposing litter in forest ecosystems supplies nutrients to plants, carbon to heterotrophic soil microorganisms and is a large source of CO2 to the atmosphere. Despite its essential role in carbon and nutrient cycling, the temperature sensitivity of leaf litter decay in tropical forest ecosystems remains poorly resolved, especially in tropical montane wet forests where the warming trend may be amplified compared to tropical wet forests at lower elevations. We quantified leaf litter decomposition rates along a highly constrained 5.2 ◦C mean annual temperature (MAT) gradient in tropical montane wet forests on the Island ofHawaii. Dominant vegetation, substrate type and age, soil moisture, and disturbance history are all nearly constant across this gradient, allowing us to isolate the effect of rising MAT on leaf litter decomposition and nutrient release. Leaf litter decomposition rates were a positive linear function of MAT, causing the residence time of leaf litter on the forest floor to decline by ∼31 days for each 1 ◦C increase in MAT. Our estimate of the Q10 temperature coefficient for leaf litter decomposition was 2.17, within the commonly reported range for heterotrophic organic matter decomposition (1.5–2.5) across a broad range of ecosystems. The percentage of leaf litter nitrogen (N) remaining after six months declined linearly with increasing MAT from ∼88% of initial N at the coolest site to ∼74% at the warmest site. The lack of net N immobilization during all three litter collection periods at all MAT plots indicates that N was not limiting to leaf litter decomposition, regardless of temperature. These results suggest that leaf litter decay in tropical montane wet forests may be more sensitive to rising MAT than in tropical lowland wet forests, and that increased rates of N release from decomposing litter could delay or prevent progressive N limitation to net primary productivity with climate warming

Improving Mean Time Between Pump Failures

Discussion Grou

A randomised controlled trial of succinylated gelatin (4%) fluid on urinary acute kidney injury biomarkers in cardiac surgical patients

Background Fluid resuscitation is frequently required for cardiac surgical patients admitted to the intensive care unit. The ideal fluid of choice in regard to efficacy and safety remains uncertain. Compared with crystalloid fluid, colloid fluid may result in less positive fluid balance. However, some synthetic colloids are associated with increased risk of acute kidney injury (AKI). This study compared the effects of succinylated gelatin (4%) (GEL) with compound sodium lactate (CSL) on urinary AKI biomarkers in patients after cardiac surgery. Methods Cardiac surgical patients who required an intravenous fluid bolus of at least 500 mL postoperatively were randomly allocated to receive GEL or CSL as the resuscitation fluid of choice for the subsequent 24 h. Primary outcomes were serial urinary neutrophil gelatinase-associated lipocalin (NGAL) and cystatin C concentrations measured at baseline, 1 h, 5 h and 24 h after enrolment, with higher concentrations indicating greater kidney injury. Secondary biomarker outcomes included urinary clusterin, α1-microglobulin and F2-isoprostanes concentrations. Differences in change of biomarker concentration between the two groups over time were compared with mixed-effects regression models. Statistical significance was set at P < 0.05. Results Forty cardiac surgical patients (n = 20 per group) with similar baseline characteristics were included. There was no significant difference in the median volume of fluid boluses administered over 24 h between the GEL (1250 mL, Q1–Q3 500–1750) and CSL group (1000 mL, Q1–Q3 500–1375) (P = 0.42). There was a significantly greater increase in urinary cystatin C (P < 0.001), clusterin (P < 0.001), α1-microglobulin (P < 0.001) and F2-isoprostanes (P = 0.020) concentrations over time in the GEL group, compared to the CSL group. Change in urinary NGAL concentration (P = 0.68) over time was not significantly different between the groups. The results were not modified by adjustment for either urinary osmolality or EuroSCORE II predicted risk of mortality. Conclusions This preliminary randomised controlled trial showed that use of succinylated gelatin (4%) for fluid resuscitation after cardiac surgery was associated with increased biomarker concentrations of renal tubular injury and dysfunction, compared to crystalloid fluid. These results generate concern that use of intravenous gelatin fluid may contribute to clinically relevant postoperative AKI

Improving Mean Time Between Pump Failures

Discussion Grou

Improving Mean Time Between Pump Failures

Discussion Grou

Progress in Payload Separation Risk Mitigation for a Deployable Venus Heat Shield

A deployable decelerator known as the Adaptive Deployable Entry and Placement Technology (ADEPT) offers substantial science and mass savings for the Venus In Situ Explorer (VISE) mission. The lander and science payload must be separated from ADEPT during atmospheric entry. This paper presents a trade study of the separation system concept of operations and provides a conceptual design of the baseline: aft-separation with a subsonic parachute. Viability of the separation system depends on the vehicle's dynamic stability characteristics during deceleration from supersonic to subsonic speeds. A trajectory sensitivity study presented shows that pitch damping and Venusian winds drive stability prior to parachute deployment, while entry spin rate is not a driver of stability below Mach 5. Additionally, progress in free-flight CFD techniques capable of computing aerodynamic damping parameters is presented. Exploratory simulations of ADEPT at a constant speed of Mach number of 0.8 suggest the vehicle may have an oscillation limit cycle near 5 angle-of-attack. The proposed separation system conceptual design is thought to be viable