1,654 research outputs found
Effect of chlortetracycline on Salmonella and the fecal flora of swine
The goals of this study were to determine the impact of sub-therapeutic chlortetracycline in market swine diets on 1) the prevalence and antimicrobial resistance of Salmonella enterica 2) antimicrobial resistance of the aerobic Gram negative fecal flora. There was no significant difference in the prevalence or antimicrobial resistance of S. enterica isolates. For the gram-negative fecal flora, there was a statistically significant difference (p\u3c0.05) between treatment groups for the frequency of antimicrobial resistance in the gram negative flora with pigs receiving chlortetracycline having a greater frequency of isolates resistant tetracycline, gentamicin, and ceftriaxone, and a lesser proportion of isolates resistant to ampicillin
Dark Matter in the Coming Decade: Complementary Paths to Discovery and Beyond
In this report we summarize the many dark matter searches currently being
pursued through four complementary approaches: direct detection, indirect
detection, collider experiments, and astrophysical probes. The essential
features of broad classes of experiments are described, each with their own
strengths and weaknesses. The complementarity of the different dark matter
searches is discussed qualitatively and illustrated quantitatively in two
simple theoretical frameworks. Our primary conclusion is that the diversity of
possible dark matter candidates requires a balanced program drawing from all
four approaches.Comment: Report prepared for the Community Summer Study (Snowmass) 2013, on
behalf of Cosmic Frontier Working Groups 1-4 (CF1: WIMP Dark Matter Direct
Detection, CF2: WIMP Dark Matter Indirect Detection, CF3: Non-WIMP Dark
Matter, and CF4: Dark Matter Complementarity); published versio
Changes in in-hospital mortality in the first wave of COVID-19: a multicentre prospective observational cohort study using the WHO Clinical Characterisation Protocol UK
BACKGROUND: Mortality rates in hospitalised patients with COVID-19 in the UK appeared to decline during the first wave of the pandemic. We aimed to quantify potential drivers of this change and identify groups of patients who remain at high risk of dying in hospital. METHODS: In this multicentre prospective observational cohort study, the International Severe Acute Respiratory and Emerging Infections Consortium WHO Clinical Characterisation Protocol UK recruited a prospective cohort of patients with COVID-19 admitted to 247 acute hospitals in England, Scotland, and Wales during the first wave of the pandemic (between March 9 and Aug 2, 2020). We included all patients aged 18 years and older with clinical signs and symptoms of COVID-19 or confirmed COVID-19 (by RT-PCR test) from assumed community-acquired infection. We did a three-way decomposition mediation analysis using natural effects models to explore associations between week of admission and in-hospital mortality, adjusting for confounders (demographics, comorbidities, and severity of illness) and quantifying potential mediators (level of respiratory support and steroid treatment). The primary outcome was weekly in-hospital mortality at 28 days, defined as the proportion of patients who had died within 28 days of admission of all patients admitted in the observed week, and it was assessed in all patients with an outcome. This study is registered with the ISRCTN Registry, ISRCTN66726260. FINDINGS: Between March 9, and Aug 2, 2020, we recruited 80 713 patients, of whom 63 972 were eligible and included in the study. Unadjusted weekly in-hospital mortality declined from 32·3% (95% CI 31·8-32·7) in March 9 to April 26, 2020, to 16·4% (15·0-17·8) in June 15 to Aug 2, 2020. Reductions in mortality were observed in all age groups, in all ethnic groups, for both sexes, and in patients with and without comorbidities. After adjustment, there was a 32% reduction in the risk of mortality per 7-week period (odds ratio [OR] 0·68 [95% CI 0·65-0·71]). The higher proportions of patients with severe disease and comorbidities earlier in the first wave (March and April) than in June and July accounted for 10·2% of this reduction. The use of respiratory support changed during the first wave, with gradually increased use of non-invasive ventilation over the first wave. Changes in respiratory support and use of steroids accounted for 22·2%, OR 0·95 (0·94-0·95) of the reduction in in-hospital mortality. INTERPRETATION: The reduction in in-hospital mortality in patients with COVID-19 during the first wave in the UK was partly accounted for by changes in the case-mix and illness severity. A significant reduction in in-hospital mortality was associated with differences in respiratory support and critical care use, which could partly reflect accrual of clinical knowledge. The remaining improvement in in-hospital mortality is not explained by these factors, and could be associated with changes in community behaviour, inoculum dose, and hospital capacity strain. FUNDING: National Institute for Health Research and the Medical Research Council
Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe
The Extragalactic Background Light (EBL) includes photons with wavelengths
from ultraviolet to infrared, which are effective at attenuating gamma rays
with energy above ~10 GeV during propagation from sources at cosmological
distances. This results in a redshift- and energy-dependent attenuation of the
gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts
(GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray
blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using
photons above 10 GeV collected by Fermi over more than one year of observations
for these sources, we investigate the effect of gamma-ray flux attenuation by
the EBL. We place upper limits on the gamma-ray opacity of the Universe at
various energies and redshifts, and compare this with predictions from
well-known EBL models. We find that an EBL intensity in the optical-ultraviolet
wavelengths as great as predicted by the "baseline" model of Stecker et al.
(2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication
in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A.
Reimer, L.C. Reye
The SWI/SNF complex acts to constrain distribution of the centromeric histone variant Cse4
In order to gain insight into the function of the Saccharomyces cerevisiae SWI/SNF complex, we have identified DNA sequences to which it is bound genomewide. One surprising observation is that the complex is enriched at the centromeres of each chromosome. Deletion of the gene encoding the Snf2 subunit of the complex was found to cause partial redistribution of the centromeric histone variant Cse4 to sites on chromosome arms. Cultures of snf2Δ yeast were found to progress through mitosis slowly. This was dependent on the mitotic checkpoint protein Mad2. In the absence of Mad2, defects in chromosome segregation were observed. In the absence of Snf2, chromatin organisation at centromeres is less distinct. In particular, hypersensitive sites flanking the Cse4 containing nucleosomes are less pronounced. Furthermore, SWI/SNF complex was found to be especially effective in the dissociation of Cse4 containing chromatin in vitro. This suggests a role for Snf2 in the maintenance of point centromeres involving the removal of Cse4 from ectopic sites
Securing the climate benefits of stable forests
Stable forests – those not already significantly disturbed nor facing predictable near-future risks of anthropogenic disturbance – may play a large role in the climate solution, due to their carbon sequestration and storage capabilities. Their importance is recognized by the Paris Agreement, but stable forests have received comparatively little attention through existing forest protection mechanisms and finance. Instead, emphasis has been placed on targeting locations where deforestation and forest degradation are happening actively. Yet stopping deforestation and forest degradation does not guarantee durable success, especially outside the geographic scope of targeted efforts. As a result, today's stable forests may be at risk without additional efforts to secure their long-term conservation.
We synthesize the gaps in existing policy efforts that could address the climate-related benefits derived from stable forests, noting several barriers to action, such as uncertainty around the level of climate services that stable forests provide and difficulties describing the real level of threat posed. We argue that resource and finance allocation for stable forests should be incorporated into countries’ and donors’ comprehensive portfolios aimed at tackling deforestation and forest degradation as well as resulting emissions. A holistic and forward-looking approach will be particularly important, given that success in tackling deforestation and forest degradation where it is currently happening will need to be sustained in the long term
Key questions for modelling COVID-19 exit strategies
Combinations of intense non-pharmaceutical interventions ('lockdowns') were
introduced in countries worldwide to reduce SARS-CoV-2 transmission. Many
governments have begun to implement lockdown exit strategies that allow
restrictions to be relaxed while attempting to control the risk of a surge in
cases. Mathematical modelling has played a central role in guiding
interventions, but the challenge of designing optimal exit strategies in the
face of ongoing transmission is unprecedented. Here, we report discussions from
the Isaac Newton Institute 'Models for an exit strategy' workshop (11-15 May
2020). A diverse community of modellers who are providing evidence to
governments worldwide were asked to identify the main questions that, if
answered, will allow for more accurate predictions of the effects of different
exit strategies. Based on these questions, we propose a roadmap to facilitate
the development of reliable models to guide exit strategies. The roadmap
requires a global collaborative effort from the scientific community and
policy-makers, and is made up of three parts: i) improve estimation of key
epidemiological parameters; ii) understand sources of heterogeneity in
populations; iii) focus on requirements for data collection, particularly in
Low-to-Middle-Income countries. This will provide important information for
planning exit strategies that balance socio-economic benefits with public
health
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