1,201 research outputs found
The impact of antiretroviral therapy on adult mortality in rural Tanzania.
OBJECTIVE: To describe the impact of antiretroviral therapy (ART) on mortality rates among adults participating in an HIV community cohort study in north-west Tanzania. METHODS: Serological and demographic surveillance rounds have been undertaken in a population of approximately 30,000 people since 1994. Free HIV care including ART has been available since 2005. Event history analysis was used to compare mortality rates among HIV-negative and HIV-positive adults in the 5-year period before and after the introduction of ART. Crude and adjusted hazard ratios were calculated using exponential regression models. Interaction between time period and HIV status was assessed to investigate whether there was a non-linear relationship between these two variables. RESULTS: Male and female mortality patterns varied over the pre- and post-ART period. In women, the crude death rate fell for both HIV negatives and HIV positives hazard rate ratio (HRR = 0.71; 95%CI 0.51-0.99 and HRR = 0.68; 95%CI: 0.46-0.99, respectively). For men, the mortality among the HIV negatives increased (HRR = 1.47; 95%CI: 1.06-2.03) while the decline in mortality among the HIV positives (HRR = 0.77; 95%CI 0.52-1.13) was not statistically significant. The largest decrease in HIV-positive mortality over the two periods was among the 30- to 44-year-old age group for women and among the 45- to 59-year-old age group for men. CONCLUSION: There has been a modest effect on mortality in the study population following the introduction of free ART 5 years ago. Improving access to treatment and placing greater focus on retaining individuals on treatment are essential if the full potential of treatment for reducing HIV-related mortality is to be realised
Asthma Prevalence, Knowledge, and Perceptions among Secondary School Pupils in Rural and Urban Costal Districts in Tanzania.
Asthma is a common chronic disease of childhood that is associated with significant morbidity and mortality. We aimed to estimate the prevalence of asthma among secondary school pupils in urban and rural areas of coast districts of Tanzania. The study also aimed to describe pupils' perception towards asthma, and to assess their knowledge on symptoms, triggers, and treatment of asthma. A total of 610 pupils from Ilala district and 619 pupils from Bagamoyo district formed the urban and rural groups, respectively. Using a modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, a history of "diagnosed" asthma or the presence of a wheeze in the previous 12 months was obtained from all the studied pupils, along with documentation of their perceptions regarding asthma. Pupils without asthma or wheeze in the prior 12 months were subsequently selected and underwent a free running exercise testing. A >= 20% decrease in the post-exercise Peak Expiratory Flow Rate (PEFR) values was the criterion for diagnosing exercise-induced asthma. The mean age of participants was 16.8 (+/-1.8) years. The prevalence of wheeze in the past 12 months was 12.1% in Bagamoyo district and 23.1% in Ilala district (p < 0.001). Self-reported asthma was found in 17.6% and 6.4% of pupils in Ilala and Bagamoyo districts, respectively (p < 0.001). The prevalence of exercise-induced asthma was 2.4% in Bagamoyo, and 26.3% in Ilala (P < 0.002). In both districts, most information on asthma came from parents, and there was variation in symptoms and triggers of asthma reported by the pupils. Non-asthmatic pupils feared sleeping, playing, and eating with their asthmatic peers. The prevalence rates of self-reported asthma, wheezing in the past 12 months, and exercise-induced asthma were significantly higher among urban than rural pupils. Although bronchial asthma is a common disease, pupils' perceptions about asthma were associated with fear of contact with their asthmatic peers in both rural and urban schools
Association between potassium concentrations, variability and supplementation, and in‑hospital mortality in ICU patients: a retrospective analysis
BACKGROUND:
Serum potassium concentrations are commonly between 3.5 and 5.0 mmol/l. Standardised protocols for potassium range and supplementation in the ICU are lacking. The purpose of this retrospective analysis of ICU patients was to investigate potassium concentrations, variability and supplementation, and their association with in-hospital mortality.
METHODS:
ICU patients ≥ 18 years, with ≥ 2 serum potassium values, treated at the Charité - Universitätsmedizin Berlin between 2006 and 2018 were eligible for inclusion. We categorised into groups of mean potassium concentrations: 3.5-4.0, > 4.0-4.5, > 4.5-5.0, > 5.0-5.5, > 5.5 mmol/l and potassium variability: 1st, 2nd and ≥ 3rd standard deviation (SD). We analysed the association between the particular groups and in-hospital mortality and performed binary logistic regression analysis. Survival curves were performed according to Kaplan-Meier and tested by Log-Rank. In a subanalysis, the association between potassium supplementation and in-hospital mortality was investigated.
RESULTS:
In 53,248 ICU patients with 1,337,742 potassium values, the lowest mortality (3.7%) was observed in patients with mean potassium concentrations between > 3.5 and 4.0 mmol/l and a low potassium variability within the 1st SD. Binary logistic regression confirmed these results. In a subanalysis of 22,406 ICU patients (ICU admission: 2013-2018), 12,892 (57.5%) received oral and/or intravenous potassium supplementation. Potassium supplementation was associated with an increase in in-hospital mortality in potassium categories from > 3.5 to 4.5 mmol/l and in the 1st, 2nd and ≥ 3rd SD (p < 0.001 each).
CONCLUSIONS:
ICU patients may benefit from a target range between 3.5 and 4.0 mmol/l and a minimal potassium variability. Clear potassium target ranges have to be determined. Criteria for widely applied potassium supplementation should be critically discussed. Trial registration German Clinical Trials Register, DRKS00016411. Retrospectively registered 11 January 2019, http://www.drks.de/DRKS00016411
Model evaluation and ensemble modelling of surface-level ozone in Europe and North America in the context of AQMEII
More than ten state-of-the-art regional air quality models have been applied as part of the Air Quality Model Evaluation International Initiative (AQMEII). These models were run by twenty independent groups in Europe and North America. Standardised modelling outputs over a full year (2006) from each group have been shared on the web-distributed ENSEMBLE system, which allows for statistical and ensemble analyses to be performed by each group. The estimated ground-level ozone mixing ratios from the models are collectively examined in an ensemble fashion and evaluated against a large set of observations from both continents. The scale of the exercise is unprecedented and offers a unique opportunity to investigate methodologies for generating skilful ensembles of regional air quality models outputs. Despite the remarkable progress of ensemble air quality modelling over the past decade, there are still outstanding questions regarding this technique. Among them, what is the best and most beneficial way to build an ensemble of members? And how should the optimum size of the ensemble be determined in order to capture data variability as well as keeping the error low? These questions are addressed here by looking at optimal ensemble size and quality of the members. The analysis carried out is based on systematic minimization of the model error and is important for performing diagnostic/probabilistic model evaluation. It is shown that the most commonly used multi-model approach, namely the average over all available members, can be outperformed by subsets of members optimally selected in terms of bias, error, and correlation. More importantly, this result does not strictly depend on the skill of the individual members, but may require the inclusion of low-ranking skill-score members. A clustering methodology is applied to discern among members and to build a skilful ensemble based on model association and data clustering, which makes no use of priori knowledge of model skill. Results show that, while the methodology needs further refinement, by optimally selecting the cluster distance and association criteria, this approach can be useful for model applications beyond those strictly related to model evaluation, such as air quality forecasting. (C) 2012 Elsevier Ltd. All rights reserved.Peer reviewe
Evidence of and search for double-charmonium production in and decays
Using data samples of and
events collected with the Belle detector, a first experimental
search has been made for double-charmonium production in the exclusive decays
, where , , , , and . No significant signal is
observed in the spectra of the mass recoiling against the reconstructed
or except for the evidence of production with a
significance of for . The
measured branching fraction \BR(\Upsilon(1S)\rightarrow J/\psi+\chi_{c1}) is
. The
confidence level upper limits on the branching fractions of the other modes
having a significance of less than are determined. These results are
consistent with theoretical calculations using the nonrelativistic QCD
factorization approach.Comment: 12 pages, 4 figures, 1 table. The fit range was extended to include
X(4160) signal according to referee's suggestions. Other results unchanged.
Paper was accepted for publication as a regular article in Physical Review
LSST Science Book, Version 2.0
A survey that can cover the sky in optical bands over wide fields to faint
magnitudes with a fast cadence will enable many of the exciting science
opportunities of the next decade. The Large Synoptic Survey Telescope (LSST)
will have an effective aperture of 6.7 meters and an imaging camera with field
of view of 9.6 deg^2, and will be devoted to a ten-year imaging survey over
20,000 deg^2 south of +15 deg. Each pointing will be imaged 2000 times with
fifteen second exposures in six broad bands from 0.35 to 1.1 microns, to a
total point-source depth of r~27.5. The LSST Science Book describes the basic
parameters of the LSST hardware, software, and observing plans. The book
discusses educational and outreach opportunities, then goes on to describe a
broad range of science that LSST will revolutionize: mapping the inner and
outer Solar System, stellar populations in the Milky Way and nearby galaxies,
the structure of the Milky Way disk and halo and other objects in the Local
Volume, transient and variable objects both at low and high redshift, and the
properties of normal and active galaxies at low and high redshift. It then
turns to far-field cosmological topics, exploring properties of supernovae to
z~1, strong and weak lensing, the large-scale distribution of galaxies and
baryon oscillations, and how these different probes may be combined to
constrain cosmological models and the physics of dark energy.Comment: 596 pages. Also available at full resolution at
http://www.lsst.org/lsst/sciboo
Observation of an alternative candidate in
We perform a full amplitude analysis of the process , where refers to either or . A new
charmoniumlike state that decays to is observed with a
significance of . Its mass is ()
MeV/ and width is () MeV. The
hypothesis is favored over the hypothesis at the level
of . The analysis is based on the 980 data sample
collected by the Belle detector at the asymmetric-energy collider
KEKB.Comment: 17 pages, 11 figure
Measurement of eta_c(1S), eta_c(2S) and non-resonant eta' pi+ pi- production via two-photon collisions
We report the measurement of gamma gamma to eta_c(1S), eta_c(2S) to eta' pi+
pi- with eta' decays to gamma rho and eta pi+ pi- using 941 fb^{-1} of data
collected with the Belle detector at the KEKB asymmetric-energy e+e- collider.
The eta_c(1S) mass and width are measured to be M = [2984.6\pm0.7 (stat.)\pm2.2
(syst.)] MeV/c^{2} and \Gamma = [30.8^{+2.3}_{-2.2}~(stat.) \pm 2.5~(syst.)]
MeV, respectively. First observation of eta_c(2S) to eta' pi+ pi- with a
significance of 5.5sigma including systematic error is obtained, and the
eta_c(2S) mass is measured to be M = [3635.1\pm3.7~(stat.)\pm2.9~(syst.)]
MeV/c^{2}. The products of the two-photon decay width and branching fraction
(B) of decays to eta'pi+ pi- are determined to be \Gamma_{gamma gamma}B =
[65.4\pm2.6~(stat.)\pm6.9~(syst.)] eV for eta_c(1S) and
[5.6^{+1.2}_{-1.1}~(stat.)\pm1.1~(syst.)] eV for eta_c(2S). A new decay mode
for the eta_c(1S) to eta'f_0(2080) with f_0(2080) to pi+ pi- is observed with a
statistical significance of 20sigma. The f_0(2080) mass and width are
determined to be M = [2083^{+63}_{-66}~(stat.)\pm 32~(syst.)] MeV/c^{2} and
\Gamma = [178^{+60}_{-178}~(stat.) \pm 55~(syst.)] MeV. The cross sections for
gamma gamma to eta' pi+ pi- and eta'f_{2}(1270) are measured for the first
time.Comment: 19 pages, 14 figure
Measurement of Branching Fractions of Hadronic Decays of the Baryon
Using a data sample of 980 of annihilation data
taken with the Belle detector operating at the KEKB asymmetric-energy
collider, we report the results of a study of the decays of the
charmed baryon into hadronic final states. We report the most precise
measurements to date of the relative branching fractions of the
into , , , and
, as well as the first measurements of the branching fractions
of the into , , and , all with respect to the decay. In
addition, we investigate the resonant substructure of these modes. Finally, we
present a limit on the branching fraction for the decay
Search for the Glueball in and decays
We report the first search for the glueball in
and decays with data samples of million and
million events, respectively, collected with the Belle detector. No
significant signals are observed in any of the proposed production modes, and
the 90\% credibility level upper limits on their branching fractions in
and decays are obtained. The inclusive branching
fractions of the and decays into final states
with a are measured to be \BR(\Upsilon(1S)\to \chi_{c1}+ anything)
= (1.90\pm 0.43(stat.)\pm 0.14(syst.))\times 10^{-4} with an improved
precision over prior measurements and \BR(\Upsilon(2S)\to \chi_{c1}+ anything)
= (2.24\pm 0.44(stat.)\pm 0.20(syst.))\times 10^{-4} for the first time.Comment: 19 pages, 17 figures, Fig.10b was polished, but all the results
unchanged. Paper was published in PR
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