706 research outputs found
Spirometry parameters used to define small airways obstruction in population-based studies: Systematic review
Background The assessment of small airways obstruction (SAO) using spirometry is practiced in population-based studies. However, it is not clear what are the most used parameters and cut-offs to define abnormal results. Methods We searched three databases (Medline, Web of Science, Google Scholar) for population-based studies, published by 1 May 2021, that used spirometry parameters to identify SAO and/or provided criteria for defining SAO. We systematically reviewed these studies and summarised evidence to determine the most widely used spirometry parameter and criteria for defining SAO. In addition, we extracted prevalence estimates and identified associated risk factors. To estimate a pooled prevalence of SAO, we conducted a meta-analysis and explored heterogeneity across studies using meta regression. Results Twenty-five studies used spirometry to identify SAO. The most widely utilised parameter (15 studies) was FEF25–75, either alone or in combination with other measurements. Ten studies provided criteria for the definition of SAO, of which percent predicted cut-offs were the most common (5 studies). However, there was no agreement on which cut-off value to use. Prevalence of SAO ranged from 7.5% to 45.9%. As a result of high heterogeneity across studies (I2 = 99.3%), explained by choice of spirometry parameter and WHO region, we do not present a pooled prevalence estimate. Conclusion There is a lack of consensus regarding the best spirometry parameter or defining criteria for identification of SAO. The value of continuing to measure SAO using spirometry is unclear without further research using large longitudinal data. PROSPERO registration number CRD4202125020
Occupational exposures and small airways obstruction in the UK Biobank Cohort
Background Small airways obstruction (SAO) is a key feature of both Chronic Obstructive Pulmonary Disease and asthma, which have been associated with workplace exposures. Whether SAO, which may occur early in the development of obstructive lung disease and without symptoms, also associates with occupational exposures is unknown. Methods Using UK Biobank data, we derived measurements of SAO from the 65,145 participants with high quality spirometry and lifetime occupational histories. The ALOHA+ Job Exposure Matrix was used to assign lifetime occupational exposures to each participant. The association between SAO and lifetime occupational exposures was evaluated using a logistic regression model adjusted for potential confounders. A second logistic regression model was run to also account for potential co-exposures. Results SAO was present in varying proportions of the population depending on definition used: 5.6% (FEF25–75<LLN)and 21.4% (FEV3/FEV6<LLN). After adjustment for confounders and co-exposures, people in the highest category of exposure to pesticides were significantly more likely to have SAO (FEV3/FEV6<LLN: OR 1.24, 95%CI 1.06–1.44). The association between pesticides and SAO showed an exposure-response pattern. SAO was also less likely among people in the highest exposure categories of aromatic solvents (FEV3/FEV6<LLN: OR 0.85, 95%CI 0.73–0.99) and metals (FEV3/FEV6<LLN: OR 0.77, 95%CI 0.62–0.94). Conclusion Our findings suggest that occupational exposure to pesticides play a role in the SAO. However, further work is needed to determine causality, and identify the specific component(s) responsible and the underlying mechanisms involved
Quantitative analysis of regulatory flexibility under changing environmental conditions
The circadian clock controls 24-h rhythms in many biological processes, allowing appropriate timing of biological rhythms relative to dawn and dusk. Known clock circuits include multiple, interlocked feedback loops. Theory suggested that multiple loops contribute the flexibility for molecular rhythms to track multiple phases of the external cycle. Clear dawn- and dusk-tracking rhythms illustrate the flexibility of timing in Ipomoea nil. Molecular clock components in Arabidopsis thaliana showed complex, photoperiod-dependent regulation, which was analysed by comparison with three contrasting models. A simple, quantitative measure, Dusk Sensitivity, was introduced to compare the behaviour of clock models with varying loop complexity. Evening-expressed clock genes showed photoperiod-dependent dusk sensitivity, as predicted by the three-loop model, whereas the one- and two-loop models tracked dawn and dusk, respectively. Output genes for starch degradation achieved dusk-tracking expression through light regulation, rather than a dusk-tracking rhythm. Model analysis predicted which biochemical processes could be manipulated to extend dusk tracking. Our results reveal how an operating principle of biological regulators applies specifically to the plant circadian clock
Measurements of Secondary Cosmic Microwave Background Anisotropies with the South Pole Telescope
We report cosmic microwave background (CMB) power spectrum measurements from
the first 100 sq. deg. field observed by the South Pole Telescope (SPT) at 150
and 220 GHz. On angular scales where the primary CMB anisotropy is dominant,
ell ~< 3000, the SPT power spectrum is consistent with the standard LambdaCDM
cosmology. On smaller scales, we see strong evidence for a point source
contribution, consistent with a population of dusty, star-forming galaxies.
After we mask bright point sources, anisotropy power on angular scales of 3000
50 at both frequencies. We
combine the 150 and 220 GHz data to remove the majority of the point source
power, and use the point source subtracted spectrum to detect
Sunyaev-Zel'dovich (SZ) power at 2.6 sigma. At ell=3000, the SZ power in the
subtracted bandpowers is 4.2 +/- 1.5 uK^2, which is significantly lower than
the power predicted by a fiducial model using WMAP5 cosmological parameters.
This discrepancy may suggest that contemporary galaxy cluster models
overestimate the thermal pressure of intracluster gas. Alternatively, this
result can be interpreted as evidence for lower values of sigma8. When combined
with an estimate of the kinetic SZ contribution, the measured SZ amplitude
shifts sigma8 from the primary CMB anisotropy derived constraint of 0.794 +/-
0.028 down to 0.773 +/- 0.025. The uncertainty in the constraint on sigma8 from
this analysis is dominated by uncertainties in the theoretical modeling
required to predict the amplitude of the SZ power spectrum for a given set of
cosmological parameters.Comment: 28 pages, 11 figures, submitted to Ap
`Standard' Cosmological model & beyond with CMB
Observational Cosmology has indeed made very rapid progress in the past
decade. The ability to quantify the universe has largely improved due to
observational constraints coming from structure formation Measurements of CMB
anisotropy and, more recently, polarization have played a very important role.
Besides precise determination of various parameters of the `standard'
cosmological model, observations have also established some important basic
tenets that underlie models of cosmology and structure formation in the
universe -- `acausally' correlated initial perturbations in a flat,
statistically isotropic universe, adiabatic nature of primordial density
perturbations. These are consistent with the expectation of the paradigm of
inflation and the generic prediction of the simplest realization of
inflationary scenario in the early universe. Further, gravitational instability
is the established mechanism for structure formation from these initial
perturbations. The signature of primordial perturbations observed as the CMB
anisotropy and polarization is the most compelling evidence for new, possibly
fundamental, physics in the early universe. The community is now looking beyond
the estimation of parameters of a working `standard' model of cosmology for
subtle, characteristic signatures from early universe physics.Comment: 16 pages, 6 figures, Plenary talk, Proc. of GR-19, Mexico City,
Mexico (Jul 5-9, 2010). To appear in a special issue in Class. Q. Gra
The Atacama Cosmology Telescope: Cosmological Parameters from the 2008 Power Spectra
We present cosmological parameters derived from the angular power spectrum of
the cosmic microwave background (CMB) radiation observed at 148 GHz and 218 GHz
over 296 deg^2 with the Atacama Cosmology Telescope (ACT) during its 2008
season. ACT measures fluctuations at scales 500<l<10000. We fit a model for the
lensed CMB, Sunyaev-Zel'dovich (SZ), and foreground contribution to the 148 GHz
and 218 GHz power spectra, including thermal and kinetic SZ, Poisson power from
radio and infrared point sources, and clustered power from infrared point
sources. The power from thermal and kinetic SZ at 148 GHz is estimated to be
B_3000 = 6.8+-2.9 uK^2, where B_l=l(l+1)C_l/2pi. We estimate primary
cosmological parameters from the 148 GHz spectrum, marginalizing over SZ and
source power. The LCDM cosmological model is a good fit to the data, and LCDM
parameters estimated from ACT+WMAP are consistent with the 7-year WMAP limits,
with scale invariant n_s = 1 excluded at 99.7% CL (3sigma). A model with no CMB
lensing is disfavored at 2.8sigma. By measuring the third to seventh acoustic
peaks, and probing the Silk damping regime, the ACT data improve limits on
cosmological parameters that affect the small-scale CMB power. The ACT data
combined with WMAP give a 6sigma detection of primordial helium, with Y_P =
0.313+-0.044, and a 4sigma detection of relativistic species, assumed to be
neutrinos, with Neff = 5.3+-1.3 (4.6+-0.8 with BAO+H0 data). From the CMB alone
the running of the spectral index is constrained to be dn/dlnk = -0.034 +-
0.018, the limit on the tensor-to-scalar ratio is r<0.25 (95% CL), and the
possible contribution of Nambu cosmic strings to the power spectrum is
constrained to string tension Gmu<1.6 \times 10^-7 (95% CL).Comment: 20 pages, 13 figures. Submitted to ApJ. This paper is a companion to
Hajian et al. (2010) and Das et al. (2010
Can We Really Prevent Suicide?
Every year, suicide is among the top 20 leading causes of death globally for all ages. Unfortunately, suicide is difficult to prevent, in large part because the prevalence of risk factors is high among the general population. In this review, clinical and psychological risk factors are examined and methods for suicide prevention are discussed. Prevention strategies found to be effective in suicide prevention
include means restriction, responsible media coverage, and general public education, as well identification methods such as screening, gatekeeper training, and primary care physician education. Although the treatment for preventing suicide is difficult, follow-up that includes pharmacotherapy, psychotherapy, or both may be useful. However, prevention methods cannot be restricted to the individual. Community, social, and policy interventions will also be essentia
Galaxy Clusters Selected with the Sunyaev-Zel'dovich Effect from 2008 South Pole Telescope Observations
We present a detection-significance-limited catalog of 21 Sunyaev-Zel'dovich
selected galaxy clusters. These clusters, along with 1 unconfirmed candidate,
were identified in 178 deg^2 of sky surveyed in 2008 by the South Pole
Telescope to a depth of 18 uK-arcmin at 150 GHz. Optical imaging from the
Blanco Cosmology Survey (BCS) and Magellan telescopes provided photometric (and
in some cases spectroscopic) redshift estimates, with catalog redshifts ranging
from z=0.15 to z>1, with a median z = 0.74. Of the 21 confirmed galaxy
clusters, three were previously identified as Abell clusters, three were
presented as SPT discoveries in Staniszewski et al, 2009, and three were first
identified in a recent analysis of BCS data by Menanteau et al, 2010; the
remaining 12 clusters are presented for the first time in this work. Simulated
observations of the SPT fields predict the sample to be nearly 100% complete
above a mass threshold of M_200 ~ 5x10^14 M_sun/h at z = 0.6. This completeness
threshold pushes to lower mass with increasing redshift, dropping to ~4x10^14
M_sun/h at z=1. The size and redshift distribution of this catalog are in good
agreement with expectations based on our current understanding of galaxy
clusters and cosmology. In combination with other cosmological probes, we use
the cluster catalog to improve estimates of cosmological parameters. Assuming a
standard spatially flat wCDM cosmological model, the addition of our catalog to
the WMAP 7-year analysis yields sigma_8 = 0.81 +- 0.09 and w = -1.07 +- 0.29, a
~50% improvement in precision on both parameters over WMAP7 alone.Comment: 19 pages, 9 figures, 4 appendice
Planck Intermediate Results. IV. The XMM-Newton validation programme for new Planck galaxy clusters
We present the final results from the XMM-Newton validation follow-up of new
Planck galaxy cluster candidates. We observed 15 new candidates, detected with
signal-to-noise ratios between 4.0 and 6.1 in the 15.5-month nominal Planck
survey. The candidates were selected using ancillary data flags derived from
the ROSAT All Sky Survey (RASS) and Digitized Sky Survey all-sky maps, with the
aim of pushing into the low SZ flux, high-z regime and testing RASS flags as
indicators of candidate reliability. 14 new clusters were detected by XMM,
including 2 double systems. Redshifts lie in the range 0.2 to 0.9, with 6
clusters at z>0.5. Estimated M500 range from 2.5 10^14 to 8 10^14 Msun. We
discuss our results in the context of the full XMM validation programme, in
which 51 new clusters have been detected. This includes 4 double and 2 triple
systems, some of which are chance projections on the sky of clusters at
different z. We find that association with a RASS-BSC source is a robust
indicator of the reliability of a candidate, whereas association with a FSC
source does not guarantee that the SZ candidate is a bona fide cluster.
Nevertheless, most Planck clusters appear in RASS maps, with a significance
greater than 2 sigma being a good indication that the candidate is a real
cluster. The full sample gives a Planck sensitivity threshold of Y500 ~ 4 10^-4
arcmin^2, with indication for Malmquist bias in the YX-Y500 relation below this
level. The corresponding mass threshold depends on z. Systems with M500 > 5
10^14 Msun at z > 0.5 are easily detectable with Planck. The newly-detected
clusters follow the YX-Y500 relation derived from X-ray selected samples.
Compared to X-ray selected clusters, the new SZ clusters have a lower X-ray
luminosity on average for their mass. There is no indication of departure from
standard self-similar evolution in the X-ray versus SZ scaling properties.
(abridged)Comment: accepted by A&
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