210 research outputs found
EXTENSION PROGRAMS ON THE SOIL BANK
Teaching/Communication/Extension/Profession,
Effects of short-term ambient PM2.5 exposure on cardiovascular disease incidence and mortality among U.S. hemodialysis patients: a retrospective cohort study
Background: Ambient PM2.5 is a ubiquitous air pollutant with demonstrated adverse health impacts in population. Hemodialysis patients are a highly vulnerable population and may be particularly susceptible to the effects of PM2.5 exposure. This study examines associations between short-term PM2.5 exposure and cardiovascular disease (CVD) and mortality among patients receiving maintenance in-center hemodialysis. Methods: Using the United State Renal Data System (USRDS) registry, we enumerated a cohort of all US adult kidney failure patients who initiated in-center hemodialysis between 1/1/2011 and 12/31/2016. Daily ambient PM2.5 exposure estimates were assigned to cohort members based on the ZIP code of the dialysis clinic. CVD incidence and mortality were ascertained through 2016 based on USRDS records. Discrete time hazards regression was used to estimate the association between lagged PM2.5 exposure and CVD incidence, CVD-specific mortality, and all-cause mortality 1 t adjusting for temperature, humidity, day of the week, season, age at baseline, race, employment status, and geographic region. Effect measure modification was assessed for age, sex, race, and comorbidities. Results: Among 314,079 hemodialysis patients, a 10 ”g/m3 increase in the average lag 0â1 daily PM2.5 exposure was associated with CVD incidence (HR: 1.03 (95% CI: 1.02, 1.04)), CVD mortality (1.05 (95% CI: 1.03, 1.08)), and all-cause mortality (1.04 (95% CI: 1.03, 1.06)). The association was larger for people who initiated dialysis at an older age, while minimal evidence of effect modification was observed across levels of sex, race, or baseline comorbidities. Conclusions: Short-term ambient PM2.5 exposure was positively associated with incident CVD events and mortality among patients receiving in-center hemodialysis. Older patients appeared to be more susceptible to PM2.5-associated CVD events than younger hemodialysis patients
Can forest management based on natural disturbances maintain ecological resilience?
Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance
Open Issues on the Synthesis of Evolved Stellar Populations at Ultraviolet Wavelengths
In this paper we briefly review three topics that have motivated our (and
others') investigations in recent years within the context of evolutionary
population synthesis techniques. These are: The origin of the FUV up-turn in
elliptical galaxies, the age-metallicity degeneracy, and the study of the
mid-UV rest-frame spectra of distant red galaxies. We summarize some of our
results and present a very preliminary application of a UV grid of theoretical
spectra in the analysis of integrated properties of aged stellar populations.
At the end, we concisely suggest how these topics can be tackled once the World
Space Observatory enters into operation in the midst of this decade.Comment: 8 pages, 4 figures, accepted for publication in Astrophysics & Space
Science, UV Universe special issu
Observation of exclusive DVCS in polarized electron beam asymmetry measurements
We report the first results of the beam spin asymmetry measured in the
reaction e + p -> e + p + gamma at a beam energy of 4.25 GeV. A large asymmetry
with a sin(phi) modulation is observed, as predicted for the interference term
of Deeply Virtual Compton Scattering and the Bethe-Heitler process. The
amplitude of this modulation is alpha = 0.202 +/- 0.028. In leading-order and
leading-twist pQCD, the alpha is directly proportional to the imaginary part of
the DVCS amplitude.Comment: 6 pages, 5 figure
A Kinematically Complete Measurement of the Proton Structure Function F2 in the Resonance Region and Evaluation of Its Moments
We measured the inclusive electron-proton cross section in the nucleon
resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2
with the CLAS detector. The large acceptance of CLAS allowed for the first time
the measurement of the cross section in a large, contiguous two-dimensional
range of Q**2 and x, making it possible to perform an integration of the data
at fixed Q**2 over the whole significant x-interval. From these data we
extracted the structure function F2 and, by including other world data, we
studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate
higher twist contributions. The small statistical and systematic uncertainties
of the CLAS data allow a precise extraction of the higher twists and demand
significant improvements in theoretical predictions for a meaningful comparison
with new experimental results.Comment: revtex4 18 pp., 12 figure
Cell Specific eQTL Analysis without Sorting Cells
The functional consequences of trait associated SNPs are often investigated using expression quantitative trait locus (eQTL) mapping. While trait-associated variants may operate in a cell-type specific manner, eQTL datasets for such cell-types may not always be available. We performed a genome-environment interaction (GxE) meta-analysis on data from 5,683 samples to infer the cell type specificity of whole blood cis-eQTLs. We demonstrate that this method is able to predict neutrophil and lymphocyte specific cis-eQTLs and replicate these predictions in independent cell-type specific datasets. Finally, we show that SNPs associated with Crohnâs disease preferentially affect gene expression within neutrophils, including the archetypal NOD2 locus
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