A guidance and control assessment of three vertical landing options for RLV

The National Aeronautics and Space Administration is considering a vertical lander as a candidate concept for a single-stage-to-orbit reusable launch vehicle (RLV). Three strategies for guiding and controlling the inversion of a reentering RLV from a nose-first attitude to a vertical landing attitude are suggested. Each option is simulated from a common reentry state to touchdown, using a common guidance algorithm and different controllers. Results demonstrate the characteristics that typify and distinguish each concept and help to identify peculiar problems, level of guidance and control sophistication required, feasibility concerns, and areas in which stringent subsystem requirements will be imposed by guidance and control

Evidence

This article is part of the District of Columbia Survey

Ion-channel-like behavior in lipid bilayer membranes at the melting transition

It is well known that at the gel-liquid phase transition temperature a lipid bilayer membrane exhibits an increased ion permeability. We analyze the quantized currents in which the increased permeability presents itself. The open time histogram shows a "-3/2" power law which implies an open-closed transition rate that decreases like $k(t) \propto t^{-1}$ as time evolves. We propose a "pore freezing" model to explain the observations. We discuss how this model also leads to the $1/f^{\alpha}$ noise that is commonly observed in currents across biological and artificial membranes.Comment: 5 pages, 4 figure

Interpersonal violence in peacetime Malawi.

Background: The contribution of interpersonal violence (IPV) to trauma burden varies greatly by region. The high rates of IPV in sub-Saharan Africa are thought to relate in part to the high rates of collective violence. Malawi, a country with no history of internal collective violence, provides an excellent setting to evaluate whether collective violence drives the high rates of IPV in this region. Methods: This is a retrospective review of a prospective trauma registry from 2009 through 2016 at Kamuzu Central Hospital in Lilongwe, Malawi. Adult (\u3e16 years) victims of IPV were compared with non-intentional trauma victims. Log binomial regression determined factors associated with increased risk of mortality for victims of IPV. Results: Of 72 488 trauma patients, 25 008 (34.5%) suffered IPV. Victims of IPV were more often male (80.2% vs. 74.8%; p Discussion: Even in a sub-Saharan country that never experienced internal collective violence, IPV injury rates are high. Public health efforts to measure and address alcohol use, and studies to determine the role of mob justice, poverty, and intimate partner violence in IPV, in Malawi are needed. Level of evidence: Level III

EM 14 - Bubbleless Gas Transfer Technology for the In Situ Remediation of Chlorinated Hydrocarbons

The primary objective of this project is to demonstrate the ability of hydrogen to supply reducing equivalents for the reductive dehalogenation of PCE. This objective will be accomplished by two types of activities. First, laboratory experiments will compare the kinetics of hydrogen-mediated dehalogenation with natural routes of loss (hydrolysis and natural attenuation). Secondly, bench-scale column experiments will be performed to demonstrate hydrogen-mediated reductive dehalogenation in aquifer sediments

Mechanisms of Groucho-mediated repression revealed by genome-wide analysis of Groucho binding and activity

Antibody validation (A) Chromatin isolated and sheared exactly as for the ChIP-seq analysis was subjected to immunoprecipitation with the indicated amounts (in μl) of affinity purified antibody against the Gro GP domain used for the ChIP-seq analysis, and then probed in a western blot with both an anti-Gro monoclonal antibody (mAb) or the anti-GP antibody. The band indicated by the asterisk is a cross-reacting protein that is recognized in the western blot but that is not efficiently immunoprecipitated by the anti-GP antibody. Ab HC – antibody heavy chain. (B) Heat map showing overlap (Jacard similarity coefficient [96]) between the peaks called in the duplicate ChIP-seq experiments at each time point. (C) Representative genome browser tracts comparing duplicate ChIP-seq experiments. (D and E) Comparison of Gro binding patterns obtained by ChIP-seq using our anti-GP antibody with that obtained by ChIP-chip (0–12 hr embryos; modENCODE #597) and ChIP-seq (white pre-pupae; modENCODE #4981) using independently derived antibodies [40]. (PDF 588 kb

Comparative outcomes between COVID-19 and influenza patients placed on veno-venous extracorporeal membrane oxygenation for severe ARDS

Background ECMO is an established supportive adjunct for patients with severe, refractory ARDS from viral pneumonia. However, the exact role and timing of ECMO for COVID-19 patients remains unclear. Methods We conducted a retrospective comparison of the first 32 patients with COVID-19-associated ARDS to the last 28 patients with influenza-associated ARDS placed on V-V ECMO. We compared patient factors between the two cohorts and used survival analysis to compare the hazard of mortality over sixty days post-cannulation.Results COVID-19 patients were older (mean 47.8 vs. 41.2 years, p = 0.033), had more ventilator days before cannulation (mean 4.5 vs. 1.5 days, p < 0.001). Crude in-hospital mortality was significantly higher in the COVID-19 cohort at 65.6% (n = 21/32) versus 36.3% (n = 11/28, p = 0.041). The adjusted hazard ratio over sixty days for COVID-19 patients was 2.81 (95% CI 1.07, 7.35) after adjusting for age, race, ECMO-associated organ failure, and Charlson Comorbidity Index. Conclusion ECMO has a role in severe ARDS associated with COVID-19 but providers should carefully weigh patient factors when utilizing this scarce resource in favor of influenza pneumonia