75 research outputs found
Modeling the actinides with disordered local moments
A first-principles disordered local moment (DLM) picture within the
local-spin-density and coherent potential approximations (LSDA+CPA) of the
actinides is presented. The parameter free theory gives an accurate description
of bond lengths and bulk modulus. The case of -Pu is studied in
particular and the calculated density of states is compared to data from
photo-electron spectroscopy. The relation between the DLM description, the
dynamical mean field approach and spin-polarized magnetically ordered modeling
is discussed.Comment: 6 pages, 4 figure
Self-optimization, community stability, and fluctuations in two individual-based models of biological coevolution
We compare and contrast the long-time dynamical properties of two
individual-based models of biological coevolution. Selection occurs via
multispecies, stochastic population dynamics with reproduction probabilities
that depend nonlinearly on the population densities of all species resident in
the community. New species are introduced through mutation. Both models are
amenable to exact linear stability analysis, and we compare the analytic
results with large-scale kinetic Monte Carlo simulations, obtaining the
population size as a function of an average interspecies interaction strength.
Over time, the models self-optimize through mutation and selection to
approximately maximize a community fitness function, subject only to
constraints internal to the particular model. If the interspecies interactions
are randomly distributed on an interval including positive values, the system
evolves toward self-sustaining, mutualistic communities. In contrast, for the
predator-prey case the matrix of interactions is antisymmetric, and a nonzero
population size must be sustained by an external resource. Time series of the
diversity and population size for both models show approximate 1/f noise and
power-law distributions for the lifetimes of communities and species. For the
mutualistic model, these two lifetime distributions have the same exponent,
while their exponents are different for the predator-prey model. The difference
is probably due to greater resilience toward mass extinctions in the food-web
like communities produced by the predator-prey model.Comment: 26 pages, 12 figures. Discussion of early-time dynamics added. J.
Math. Biol., in pres
Catholic Healthcare Organizations and the Articulation of Their Identity
Contains fulltext :
69947.pdf (publisher's version ) (Open Access
Black Hole, Jet, and Disk: The Universal Engine
In this paper I review the results of our ongoing project to investigate the
coupling between accretion disk and radio jet in galactic nuclei and stellar
mass black holes. We find a good correlation between the UV bump luminosity and
the radio luminosities of AGN, which improves upon the usual [OIII]/radio
correlations. Taking mass and energy conservation in the jet/disk system into
account we can successfully model the correlation for radio-loud and radio-weak
quasars. We find that jets are comparable in power to the accretion disk
luminosity, and the difference between radio-loud and radio-weak may correspond
to two natural stages of the relativistic electron distribution -- assuming
that radio weak quasars have jets as well. The distribution of flat- and
steep-spectrum sources is explained by bulk Lorentz factors gamma_j ~ 5-10. The
absence of radio-loud quasars below a critical optical luminosity coincides
with the FR I/FR II break and could be explained by a powerdependent,
``closing'' torus. This points towards a different type of obscuring torus in
radio-loud host galaxies which might be a consequence of past mergers (e.g. by
the temporary formation of a binary black-hole). Interaction of the jet with
the closing torus might in principle also help to make a jet radio-loud.
Turning to stellar-mass black holes we find that galactic jet sources can be
described with the same coupled jet/disk model as AGN which is suggestive of
some kind of universal coupling between jet and accretion disk around compact
objects.Comment: to appear in ``Jets from Stars and Galactic Nuclei'', Springer
Lecture Notes, plain TeX, 16 pages, also at
http://www.astro.umd.edu/~hfalcke/publications.htm
Clarifying values: an updated and expanded systematic review and meta-analysis
Background
Patient decision aids should help people make evidence-informed decisions aligned with their values. There is limited guidance about how to achieve such alignment.
Purpose
To describe the range of values clarification methods available to patient decision aid developers, synthesize evidence regarding their relative merits, and foster collection of evidence by offering researchers a proposed set of outcomes to report when evaluating the effects of values clarification methods.
Data Sources
MEDLINE, EMBASE, PubMed, Web of Science, the Cochrane Library, and CINAHL.
Study Selection
We included articles that described randomized trials of 1 or more explicit values clarification methods. From 30,648 records screened, we identified 33 articles describing trials of 43 values clarification methods.
Data Extraction
Two independent reviewers extracted details about each values clarification method and its evaluation.
Data Synthesis
Compared to control conditions or to implicit values clarification methods, explicit values clarification methods decreased the frequency of values-incongruent choices (risk difference, –0.04; 95% confidence interval [CI], –0.06 to –0.02; P < 0.001) and decisional conflict (standardized mean difference, –0.20; 95% CI, –0.29 to –0.11; P < 0.001). Multicriteria decision analysis led to more values-congruent decisions than other values clarification methods (χ2 = 9.25, P = 0.01). There were no differences between different values clarification methods regarding decisional conflict (χ2 = 6.08, P = 0.05).
Limitations
Some meta-analyses had high heterogeneity. We grouped values clarification methods into broad categories.
Conclusions
Current evidence suggests patient decision aids should include an explicit values clarification method. Developers may wish to specifically consider multicriteria decision analysis. Future evaluations of values clarification methods should report their effects on decisional conflict, decisions made, values congruence, and decisional regret
Impact of Chlamydia trachomatis in the reproductive setting: British Fertility Society Guidelines for practice
Chlamydia trachomatis infection of the genital tract is the most common sexually transmitted infection and has a world-wide distribution. The consequences of infection have an adverse effect on the reproductive health of women and are a common cause of infertility. Recent evidence also suggests an adverse effect on male reproduction. There is a need to standardise the approach in managing the impact of C. trachomatis infection on reproductive health. We have surveyed current UK practice towards screening and management of Chlamydia infections in the fertility setting. We found that at least 90% of clinicians surveyed offered screening. The literature on this topic was examined and revealed a paucity of solid evidence for estimating the risks of long-term reproductive sequelae following lower genital tract infection with C. trachomatis. The mechanism for the damage that occurs after Chlamydial infections is uncertain. However, instrumentation of the uterus in women with C. trachomatis infection is associated with a high risk of pelvic inflammatory disease, which can be prevented by appropriate antibiotic treatment and may prevent infected women from being at increased risk of the adverse sequelae, such as ectopic pregnancy and tubal factor infertility. Recommendations for practice have been proposed and the need for further studies is identified
Tocilizumab in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial
Background:
In this study, we aimed to evaluate the effects of tocilizumab in adult patients admitted to hospital with COVID-19 with both hypoxia and systemic inflammation.
Methods:
This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. Those trial participants with hypoxia (oxygen saturation <92% on air or requiring oxygen therapy) and evidence of systemic inflammation (C-reactive protein ≥75 mg/L) were eligible for random assignment in a 1:1 ratio to usual standard of care alone versus usual standard of care plus tocilizumab at a dose of 400 mg–800 mg (depending on weight) given intravenously. A second dose could be given 12–24 h later if the patient's condition had not improved. The primary outcome was 28-day mortality, assessed in the intention-to-treat population. The trial is registered with ISRCTN (50189673) and ClinicalTrials.gov (NCT04381936).
Findings:
Between April 23, 2020, and Jan 24, 2021, 4116 adults of 21 550 patients enrolled into the RECOVERY trial were included in the assessment of tocilizumab, including 3385 (82%) patients receiving systemic corticosteroids. Overall, 621 (31%) of the 2022 patients allocated tocilizumab and 729 (35%) of the 2094 patients allocated to usual care died within 28 days (rate ratio 0·85; 95% CI 0·76–0·94; p=0·0028). Consistent results were seen in all prespecified subgroups of patients, including those receiving systemic corticosteroids. Patients allocated to tocilizumab were more likely to be discharged from hospital within 28 days (57% vs 50%; rate ratio 1·22; 1·12–1·33; p<0·0001). Among those not receiving invasive mechanical ventilation at baseline, patients allocated tocilizumab were less likely to reach the composite endpoint of invasive mechanical ventilation or death (35% vs 42%; risk ratio 0·84; 95% CI 0·77–0·92; p<0·0001).
Interpretation:
In hospitalised COVID-19 patients with hypoxia and systemic inflammation, tocilizumab improved survival and other clinical outcomes. These benefits were seen regardless of the amount of respiratory support and were additional to the benefits of systemic corticosteroids.
Funding:
UK Research and Innovation (Medical Research Council) and National Institute of Health Research
Whole-genome sequencing reveals host factors underlying critical COVID-19
Critical COVID-19 is caused by immune-mediated inflammatory lung injury. Host genetic variation influences the development of illness requiring critical care1 or hospitalization2,3,4 after infection with SARS-CoV-2. The GenOMICC (Genetics of Mortality in Critical Care) study enables the comparison of genomes from individuals who are critically ill with those of population controls to find underlying disease mechanisms. Here we use whole-genome sequencing in 7,491 critically ill individuals compared with 48,400 controls to discover and replicate 23 independent variants that significantly predispose to critical COVID-19. We identify 16 new independent associations, including variants within genes that are involved in interferon signalling (IL10RB and PLSCR1), leucocyte differentiation (BCL11A) and blood-type antigen secretor status (FUT2). Using transcriptome-wide association and colocalization to infer the effect of gene expression on disease severity, we find evidence that implicates multiple genes—including reduced expression of a membrane flippase (ATP11A), and increased expression of a mucin (MUC1)—in critical disease. Mendelian randomization provides evidence in support of causal roles for myeloid cell adhesion molecules (SELE, ICAM5 and CD209) and the coagulation factor F8, all of which are potentially druggable targets. Our results are broadly consistent with a multi-component model of COVID-19 pathophysiology, in which at least two distinct mechanisms can predispose to life-threatening disease: failure to control viral replication; or an enhanced tendency towards pulmonary inflammation and intravascular coagulation. We show that comparison between cases of critical illness and population controls is highly efficient for the detection of therapeutically relevant mechanisms of disease
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Total Measurement Uncertainty (TMU) for Nondestructive Assay of Transuranic (TRU) Waste at the WRAP Facility
This report examines the contributing factors to NDA measurement uncertainty at WRAP The significance of each factor on the TMU is analyzed and a final method is given for determining the TMU for NDA measurements at WRAP. As more data becomes available and WRAP gains in operational experience this report will be reviewed semi annually and updated as necessary
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QA Objectives for Nondestructive Assay at the Waste Receiving and Processing (WRAP) Facility
This report summarizes the validation of the WRAP NDA systems against the various QAOs. A brief description of each test and any significant conclusions is included. Variables which may have affected test outcomes are examined. This report will be reviewed semi-annually and updated as necessary
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