19 research outputs found
Derepression of the smvA Efflux System Arises in Clinical Isolates of Proteus mirabilis and Reduces Susceptibility to Chlorhexidine and Other Biocides
Hopf algebras and Markov chains: Two examples and a theory
The operation of squaring (coproduct followed by product) in a combinatorial
Hopf algebra is shown to induce a Markov chain in natural bases. Chains
constructed in this way include widely studied methods of card shuffling, a
natural "rock-breaking" process, and Markov chains on simplicial complexes.
Many of these chains can be explictly diagonalized using the primitive elements
of the algebra and the combinatorics of the free Lie algebra. For card
shuffling, this gives an explicit description of the eigenvectors. For
rock-breaking, an explicit description of the quasi-stationary distribution and
sharp rates to absorption follow.Comment: 51 pages, 17 figures. (Typographical errors corrected. Further fixes
will only appear on the version on Amy Pang's website, the arXiv version will
not be updated.
Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19
IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19.
Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19.
DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 nonâcritically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022).
INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (nâ=â257), ARB (nâ=â248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; nâ=â10), or no RAS inhibitor (control; nâ=â264) for up to 10 days.
MAIN OUTCOMES AND MEASURES The primary outcome was organ supportâfree days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes.
RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ supportâfree days among critically ill patients was 10 (â1 to 16) in the ACE inhibitor group (nâ=â231), 8 (â1 to 17) in the ARB group (nâ=â217), and 12 (0 to 17) in the control group (nâ=â231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ supportâfree days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively).
CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
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SRS Geology/Hydrogeology Environmental Information Document
The purpose of the Savannah River Site Geology and Hydrogeology Environmental Information Document (EID) is to provide geologic and hydrogeologic information to serve as a baseline to evaluate potential environmental impacts. This EID is based on a summary of knowledge accumulated from research conducted at the Savannah River Site (SRS) and surrounding areas
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Natural Strontium, Iodine, Cesium, and Cobalt in Savannah River Site Groundwater: Data Report
The purpose of this investigation was to obtain baseline groundwater concentrations for naturally occurring stable isotopes of Sr, I, Cs, and Co in shallow aquifers at the Savannah River Site. These data are necessary to fully understand migration and remediation of 90Sr, 129I, 137Cs, and 60Co. Fourteen P-wells were selected and sampled based on their close proximity to facilities, available water table and Gordon aquifer wells, and archived core. This report provides the analytical results from the groundwater sampling and core leaching studies. Several radioactive contaminants have naturally occurring counterparts that are non-radioactive, but have chemical behavior that is identical to the radioactive contaminants. These naturally occurring isotopes are typically present in groundwater at mass concentrations that are orders of magnitude greater than their associated radionuclides. A consequence of this is that the natural constituents compete for adsorption and cation exchange site s with their radioactive counterparts, reducing retardation of the radioactive species. Hence, the concentrations of these natural species are important to the modeling of monitored natural attenuation, performance assessments, and other regulatory documents that require a fate and transport analysis
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The Speciation of Groundwater Contaminated with Coal Pile Leachate at the Savannah River Site, South Carolina
Modeling the transport of contaminant metals and designing systems for their remediation requires an understanding of the metal`s speciation. Thus, analysis of contaminant speciation and evaluation of the processes that can change the speciation should be done during characterization of the contaminated site. This approach is being used at the Savannah River Site for a metals contaminated site that will serve as a test platform for metals remediation technologies. The site is adjacent to a coal storage pile and the basin that contains the coal pile runoff. A network of well clusters allows definition of the plume, including profiles of contamination with depth. The groundwater is acidic (pH {approx} 2) and contains high concentrations of sulfate (up to 2300 mg/l) and metals, with chromium, nickel, cadmium and lead exceeding drinking water standards. Aluminum and total iron concentrations range up to 1326 mg/l and 7991 mg/l, respectively. Speciation calculations on dissolved contaminants indicate that as much as 65% of the lead, 54% of the cadmium, and 34% of the nickel may be present in sulfate complexes. Chromium occurs predominantly as Cr{sup +3}. There is evidence that some contaminant metals may be associated with colloidal material. Contamination in the groundwater is stratified with concentrations decreasing over a depth range of 3 meters (10 feet). Fluid-rock interactions explain the non-uniform behavior of dissolved components with depth. Mass balance considerations suggest that the interactions are dominated by Kaolinite dissolution coupled with precipitation of phases containing aluminum, ferric iron, silica, and sulfate, as well as co- precipitation of contaminant metals