926 research outputs found
The impact of current CH4 and N2O atmospheric loss process uncertainties on calculated ozone abundances and trends
The atmospheric loss processes of N2O and CH4, their estimated uncertainties, lifetimes, and impacts on ozone abundance and long-term trends are examined using atmospheric model calculations and updated kinetic and photochemical parameters and uncertainty factors from SPARC [2013]. The uncertainty ranges in calculated N2O and CH4 global lifetimes computed using the SPARC estimated uncertainties are reduced by nearly a factor of two compared with uncertainties from Sander et al. [2011]. Uncertainties in CH4 loss due to reaction with OH and O(1D) have relatively small impacts on present day global total ozone (±0.2-0.3%). Uncertainty in the Cl + CH4 reaction affects the amount of chlorine in radical vs. reservoir forms and has a modest impact on present day SH polar ozone (~±6%), and on the rate of past ozone decline and future recovery. Uncertainty in the total rate coefficient for the O(1D) + N2O reaction results in a substantial range in present day stratospheric odd nitrogen (±20-25%) and global total ozone (±1.5-2.5%). Uncertainty in the O(1D) + N2O reaction branching ratio for the O2 + N2 and 2*NO product channels results in moderate impacts on odd nitrogen (±10%) and global ozone (±1%),with uncertainty in N2O photolysis resulting in relatively small impacts (±5% in odd nitrogen, ±0.5% in global ozone). Uncertainties in the O(1D) + N2O reaction and its branching ratio also affect the rate of past global total ozone decline and future recovery, with a range in future ozone projections of ±1-1.5% by 2100, relative to present day
Ferritins: furnishing proteins with iron
Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores and examine in detail how three selected ferritins oxidise Fe2+ in order to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins
Does publication bias inflate the apparent efficacy of psychological treatment for major depressive disorder? A systematic review and meta-analysis of US national institutes of health-funded trials
Background The efficacy of antidepressant medication has been shown empirically to be overestimated due to publication bias, but this has only been inferred statistically with regard to psychological treatment for depression. We assessed directly the extent of study publication bias in trials examining the efficacy of psychological treatment for depression. Methods and Findings We identified US National Institutes of Health grants awarded to fund randomized clinical trials comparing psychological treatment to control conditions or other treatments in patients diagnosed with major depressive disorder for the period 1972–2008, and we determined whether those grants led to publications. For studies that were not published, data were requested from investigators and included in the meta-analyses. Thirteen (23.6%) of the 55 funded grants that began trials did not result in publications, and two others never started. Among comparisons to control conditions, adding unpublished studies (Hedges’ g = 0.20; CI95% -0.11~0.51; k = 6) to published studies (g = 0.52; 0.37~0.68; k = 20) reduced the psychotherapy effect size point estimate (g = 0.39; 0.08~0.70) by 25%. Moreover, these findings may overestimate the "true" effect of psychological treatment for depression as outcome reporting bias could not be examined quantitatively. Conclusion The efficacy of psychological interventions for depression has been overestimated in the published literature, just as it has been for pharmacotherapy. Both are efficacious but not to the extent that the published literature would suggest. Funding agencies and journals should archive both original protocols and raw data from treatment trials to allow the detection and correction of outcome reporting bias. Clinicians, guidelines developers, and decision makers should be aware that the published literature overestimates the effects of the predominant treatments for depression
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV
The performance of muon reconstruction, identification, and triggering in CMS
has been studied using 40 inverse picobarns of data collected in pp collisions
at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection
criteria covering a wide range of physics analysis needs have been examined.
For all considered selections, the efficiency to reconstruct and identify a
muon with a transverse momentum pT larger than a few GeV is above 95% over the
whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4,
while the probability to misidentify a hadron as a muon is well below 1%. The
efficiency to trigger on single muons with pT above a few GeV is higher than
90% over the full eta range, and typically substantially better. The overall
momentum scale is measured to a precision of 0.2% with muons from Z decays. The
transverse momentum resolution varies from 1% to 6% depending on pseudorapidity
for muons with pT below 100 GeV and, using cosmic rays, it is shown to be
better than 10% in the central region up to pT = 1 TeV. Observed distributions
of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO
A Search for Dark Higgs Bosons
Recent astrophysical and terrestrial experiments have motivated the proposal
of a dark sector with GeV-scale gauge boson force carriers and new Higgs
bosons. We present a search for a dark Higgs boson using 516 fb-1 of data
collected with the BABAR detector. We do not observe a significant signal and
we set 90% confidence level upper limits on the product of the Standard
Model-dark sector mixing angle and the dark sector coupling constant.Comment: 7 pages, 5 postscript figures, published version with improved plots
for b/w printin
Measurement of Higgs boson production and properties in the WW decay channel with leptonic final states
Peer reviewe
Emergency pulpotomy in relieving acute dental pain among Tanzanian patients
BACKGROUND: In Tanzania, oral health services are mostly in the form of dental extractions aimed at alleviating acute dental pain. Conservative methods of alleviating acute dental pain are virtually non-existent. Therefore, it was the aim of this study to determine treatment success of emergency pulpotomy in relieving acute dental pain. METHODS: Setting: School of Dentistry, Muhimbili National Hospital, Dar es Salaam, Tanzania. Study design: Longitudinal study. Participants: 180 patients who presented with dental pain due to acute irreversible pulpitis during the study period between July and August 2001. Treatment and evaluation: Patients were treated by emergency pulpotomy on permanent posterior teeth and were evaluated for pain after one, three and six week's post-treatment. Pain, if present, was categorised as either mild or acute. RESULTS: Of the patients with treated premolars, 25 (13.9%) patients did not experience pain at all while 19 (10.6%) experienced mild pain. None of the patients with treated premolars experienced acute pain. Among 136 patients with treated molars 56 (31%) did not experience any pain, 76 (42.2%) experienced mild pain and the other 4 (2.2%) suffered acute pain. CONCLUSION: The short term treatment success of emergency pulpotomy was high being 100% for premolars and 97.1% for molars, suggesting that it can be recommended as a measure to alleviate acute dental pain while other conservative treatment options are being considered
Study of double parton scattering using W+2-jet events in proton-proton collisions at √s=7 TeV
Peer reviewe
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