Monte Carlo of Trapped Ultracold Neutrons in the UCNτ Trap

In the UCNτ experiment, ultracold neutrons (UCN) are confined by magnetic fields and the Earth’s gravitational field. Field-trapping mitigates the problem of UCN loss on material surfaces, which caused the largest correction in prior neutron experiments using material bottles. However, the neutron dynamics in field traps differ qualitatively from those in material bottles. In the latter case, neutrons bounce off material surfaces with significant diffusivity and the population quickly reaches a static spatial distribution with a density gradient induced by the gravitational potential. In contrast, the field-confined UCN—whose dynamics can be described by Hamiltonian mechanics—do not exhibit the stochastic behaviors typical of an ideal gas model as observed in material bottles. In this report, we will describe our efforts to simulate UCN trapping in the UCNτ magneto-gravitational trap. We compare the simulation output to the experimental results to determine the parameters of the neutron detector and the input neutron distribution. The tuned model is then used to understand the phase space evolution of neutrons observed in the UCNτ experiment. We will discuss the implications of chaotic dynamics on controlling the systematic effects, such as spectral cleaning and microphonic heating, for a successful UCN lifetime experiment to reach a 0.01% level of precision

Rationale and design of the STeroids to REduce Systemic inflammation after infant heart Surgery (STRESS) trial

For decades, physicians have administered corticosteroids in the perioperative period to infants undergoing heart surgery with cardiopulmonary bypass (CPB) to reduce the postoperative systemic inflammatory response to CPB. Some question this practice because steroid efficacy has not been conclusively demonstrated and because some studies indicate that steroids could have harmful effects. STRESS is a randomized, placebo-controlled, double-blind, multicenter trial designed to evaluate safety and efficacy of perioperative steroids in infants (age \u3c 1 year) undergoing heart surgery with CPB. Participants (planned enrollment = 1,200) are randomized 1:1 to methylprednisolone (30 mg/kg) administered into the CPB pump prime versus placebo. The trial is nested within the existing infrastructure of the Society of Thoracic Surgeons Congenital Heart Surgery Database. The primary outcome is a global rank score of mortality, major morbidities, and hospital length of stay with components ranked commensurate with their clinical severity. Secondary outcomes include several measures of major postoperative morbidity, postoperative hospital length of stay, and steroid-related safety outcomes including prevalence of hyperglycemia and postoperative infectious complications. STRESS will be one of the largest trials ever conducted in children with heart disease and will answer a decades-old question related to safety and efficacy of perioperative steroids in infants undergoing heart surgery with CPB. The pragmatic trial within a registry design may provide a mechanism for conducting low-cost, high-efficiency trials in a heretofore-understudied patient population

Evaluating Real-World National and Regional Trends in Definitive Closure in U.S. Burn Care: A Survey of U.S. Burn Centers.

To better understand trends in burn treatment patterns related to definitive closure, this study sought to benchmark real-world survey data with national data contained within the National Burn Repository version 8.0 (NBR v8.0) across key burn center practice patterns, resource utilization, and clinical outcomes. A survey, administered to a representative sample of U.S. burn surgeons, collected information across several domains: burn center characteristics, patient characteristics including number of patients and burn size and depth, aggregate number of procedures, resource use such as autograft procedure time and dressing changes, and costs. Survey findings were aggregated by key outcomes (number of procedures, costs) nationally and regionally. Aggregated burn center data were also compared to the NBR to identify trends relative to current treatment patterns. Benchmarking survey results against the NBR v8.0 demonstrated shifts in burn center patient mix, with more severe cases being seen in the inpatient setting and less severe burns moving to the outpatient setting. An overall reduction in the number of autograft procedures was observed compared to NBR v8.0, and time efficiencies improved as the intervention time per TBSA decreases as TBSA increases. Both nationally and regionally, an increase in costs was observed. The results suggest resource use estimates from NBR v8.0 may be higher than current practices, thus highlighting the importance of improved and timely NBR reporting and further research on burn center standard of care practices. This study demonstrates significant variations in burn center characteristics, practice patterns, and resource utilization, thus increasing our understanding of burn center operations and behavior