1,067 research outputs found
A meta‐analysis of published studies of endothelial dysfunction does not support its routine clinical use
Summary Background Endothelial dysfunction is a marker of future cardiovascular disease (CVD) risk, yet epidemiological studies have yielded inconsistent results. We therefore studied the association between endothelial dysfunction and CVD under diverse circumstances. Methods and results Literature-based meta-analysis of prospective observational studies with ≥ 12 months of follow-up published in Medline and having information on endothelial function and CVD outcomes. Tabular data on participant characteristics, endothelial function assessments and incident CVD outcomes were abstracted from individual studies. Random-effects meta-analysis was used to quantify pooled associations, and I2 statistic to evaluate between-study heterogeneity. Potential sources of heterogeneity were explored by subgroup analyses and meta-regression. Thirty five studies involving 17,206 participants met the inclusion criteria. During more than 80,000 person-years of observation, up to 2755 CVD events were accrued, yielding a pooled relative risk (RR) of 1.25 (95% confidence interval 1.15–1.35) for CVD comparing top (i.e. more severe) vs. bottom (less severe) third of endothelial dysfunction. There was significant between-study heterogeneity and evidence of publication bias. RRs varied importantly according to the method used to ascertain endothelial function, and were higher among older individuals and among participants with risk factors for CVD or established CVD at baseline. Conclusions Although endothelial dysfunction is an important determinant of cardiovascular outcomes in people with pre-existing CVD, current evidence base does not support its use as a potentially useful measurement for risk stratification in people at lower risk of CVD
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Climate information to support wildlife management in the North Central United States
This paper investigates what is needed to make climate and weather information more usable for the wildlife management practitioners and ecological researchers in the Prairie Potholes Region (PPR) of the North Central United States. Using interviews, policy document analysis, and participant observation, we identify climate and weather information needs, barriers to use, and opportunities to provide better information to these users. We found that the research and management communities need guidance on how to interpret and apply existing information. Climate information needs in the PPR are driven by the need to understand how projected changes in precipitation will impact prairie wetland ecology. Primary needs include guidance towards selecting, interpreting, and using various climate information products to understand impacts and explanations of the differences between new products and previously available information. Another need includes information on how the societal responses to climate change will further impact ecological systems. Existing management priorities, limited institutional resources, and limited ecological data are remaining barriers that can be ameliorated by leveraging existing policy processes or trusted sources of information to provide guidance, thereby reducing time and costs associated with using climate information in wildlife policy planning. Throughout, we emphasize the importance of the social and ecological aspects of the decision-making context to shape climate information needs, barriers, and entry points. Additional research is needed on the diverse ways that users engage with and use climate information, and additional efforts are needed to co-produce guidance documents that interpret climate information for management and research communities.</p
New Pulsars from an Arecibo Drift Scan Search
We report the discovery of pulsars J0030+0451, J0711+0931, and J1313+0931
that were found in a search of 470 square degrees at 430 MHz using the 305m
Arecibo telescope. The search has an estimated sensitivity for long period, low
dispersion measure, low zenith angle, and high Galactic latitude pulsars of ~1
mJy, comparable to previous Arecibo searches. Spin and astrometric parameters
for the three pulsars are presented along with polarimetry at 430 MHz. PSR
J0030+0451, a nearby pulsar with a period of 4.8 ms, belongs to the less common
category of isolated millisecond pulsars. We have measured significant
polarization in PSR J0030+0451 over more than 50% of the period, and use these
data for a detailed discussion of its magnetospheric geometry. Scintillation
observations of PSR J0030+0451 provide an estimate of the plasma turbulence
level along the line of sight through the local interstellar medium.Comment: 21 pages, 4 figures, Accepted for Publication in Ap
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A predictive model for seasonal pond counts in the United States Prairie Pothole Region using large-scale climate connections
The Prairie Pothole Region (PPR), located in central North America, is an important region hydrologically and ecologically. Millions of wetlands, many containing ponds, are located here, and they serve as habitats for various biota and breeding grounds for waterfowl. They also provide carbon sequestration, sediment and nutrient attenuation, and floodwater storage. Land modification and climate change are threatening the PPR, and water and wildlife managers face important conservation decisions due to these threats. We developed predictive, multisite forecasting models using canonical correlation analysis (CCA) for pond counts in the southeast PPR, the portion located within the United States, to aid in these important decisions. These forecast models predict spring (May) and summer (July) pond counts for each region (stratum) of the United States Fish and Wildlife Service's pond and waterfowl surveys using a suite of antecedent, large-scale climate variables and indices including 500 millibar heights, sea surface temperatures (SSTs), and Palmer Drought Severity Index (PDSI). Models were developed to issue forecasts at the start of all preceding months beginning on March 1st. The models were evaluated for their performance in a predictive mode by leave-one-out cross-validation. The models exhibited good performance (R values above 0.6 for May forecasts and 0.4 for July forecasts), with performance increasing as lead time decreased. This simple and versatile modeling approach offers a robust tool for efficient management and sustainability of ecology and natural resources. It demonstrates the ability to use large-scale climate variables to predict a local variable in a skilful way and could serve as an example to develop similar models for use in management and conservation decisions in other regions and sectors of the environment.
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Mechanisms of Alcohol Addiction: Bridging Human and Animal Studies
Aim: The purpose of this brief narrative review is to address the complexities and benefits of extending animal alcohol addiction research to the human domain, emphasizing Allostasis and Incentive Sensitization, two models that inform many pre-clinical and clinical studies. Methods: The work reviewed includes a range of approaches, including: a) animal and human studies that target the biology of craving and compulsive consumption; b) human investigations that utilize alcohol self-administration and alcohol challenge paradigms, in some cases across 10 years; c) questionnaires that document changes in the positive and negative reinforcing effects of alcohol with increasing severity of addiction; and d) genomic structural equation modeling based on data from animal and human studies. Results: Several general themes emerge from specific study findings. First, positive reinforcement is characteristic of early stage addiction and sometimes diminishes with increasing severity, consistent with both Allostasis and Incentive Sensitization. Second, evidence is less consistent for the predominance of negative reinforcement in later stages of addiction, a key tenant of Allostasis. Finally, there are important individual differences in motivation to drink at a given point in time as well as person-specific change patterns across time. Conclusions: Key constructs of addiction, like stage and reinforcement, are by necessity operationalized differently in animal and human studies. Similarly, testing the validity of addiction models requires different strategies by the two research domains. Although such differences are challenging, they are not insurmountable, and there is much to be gained in understanding and treating addiction by combining pre-clinical and clinical approaches.Fil: Kramer, John. University of Iowa; Estados UnidosFil: Dick, Danielle M.. University of Virginia; Estados UnidosFil: King, Andrea. University of Chicago; Estados UnidosFil: Ray, Lara A.. University of California at Los Angeles; Estados UnidosFil: Sher, Kenneth J.. University of Missouri; Estados UnidosFil: Vena, Ashley. University of Chicago; Estados UnidosFil: Vendruscolo, Leandro F.. National Institutes of Health; Estados UnidosFil: Acion, Laura. University of Iowa; Estados Unidos. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Calculo. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Calculo; Argentin
The Identification of the X-ray Counterpart to PSR J2021+4026
We report the probable identification of the X-ray counterpart to the
gamma-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray
Observatory ACIS and timing analysis with the Fermi satellite. Given the
statistical and systematic errors, the positions determined by both satellites
are coincident. The X-ray source position is R.A. 20h21m30.733s, Decl. +40 deg
26 min 46.04sec (J2000) with an estimated uncertainty of 1.3 arsec combined
statistical and systematic error. Moreover, both the X-ray to gamma-ray and the
X-ray to optical flux ratios are sensible assuming a neutron star origin for
the X-ray flux. The X-ray source has no cataloged infrared-to-visible
counterpart and, through new observations, we set upper limits to its optical
emission of i' >23.0 mag and r' > 25.2mag. The source exhibits an X-ray
spectrum with most likely both a powerlaw and a thermal component. We also
report on the X-ray and visible light properties of the 43 other sources
detected in our Chandra observation.Comment: Accepted for publication in the Astrophysical Journa
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Hydroclimate Variability and Change in the Prairie Pothole Region, the “Duck Factory” of North America
The Prairie Pothole Region (PPR) of the northern Great Plains is a vital ecosystem responsible each year for producing 50%–80% of new recruits to the North American duck population. Climate variability and change can impact the hydrology and ecology of the region with implications for waterfowl populations. The historical relationship between PPR wetlands, duck populations, and seasonal hydroclimate are explored. Model experiments from phase 5 of the Coupled Model Intercomparison Project are used to determine whether a recent wetting trend is due to natural variability or changing climate and how PPR hydroclimate will change into the future. Year-to-year variations in May duck populations, pond numbers, and the Palmer drought severity index are well correlated over past decades. Pond and duck numbers tend to increase in spring following La Niña events, but the correlation is not strong. Model simulations suggest that the strengthening of the precipitation gradient across the PPR over the past century is predominantly due to natural variability and therefore could reverse. Model projections of future climate indicate precipitation will increase across the PPR in all seasons except summer, but this gain for surface moisture is largely offset by increased evapotranspiration because of higher temperatures and increased atmospheric evaporative demand. In summer, the combined effects of warming and precipitation changes indicate seasonal surface drying in the future. The presented hydroclimate analyses produce potential inputs to ecological and hydrological simulations of PPR wetlands to inform risk analysis of how this North American waterfowl habitat will evolve in the future, providing guidance to land managers facing conservation decisions
The interstellar medium and feedback in the progenitors of the compact passive galaxies at z~2
Quenched galaxies at z>2 are nearly all very compact relative to z~0,
suggesting a physical connection between high stellar density and efficient,
rapid cessation of star-formation. We present restframe UV spectra of
Lyman-break galaxies (LBGs) at z~3 selected to be candidate progenitors of
quenched galaxies at z~2 based on their compact restframe optical sizes and
high surface density of star-formation. We compare their UV properties to those
of more extended LBGs of similar mass and star formation rate (non-candidates).
We find that candidate progenitors have faster ISM gas velocities and higher
equivalent widths of interstellar absorption lines, implying larger velocity
spread among absorbing clouds. Candidates deviate from the relationship between
equivalent widths of Lyman-alpha and interstellar absorption lines in that
their Lyman-alpha emission remains strong despite high interstellar absorption,
possibly indicating that the neutral HI fraction is patchy such that
Lyman-alpha photons can escape. We detect stronger CIV P-Cygni features
(emission and absorption) and HeII emission in candidates, indicative of larger
populations of metal rich Wolf-Rayet stars compared to non-candidates. The
faster bulk motions, broader spread of gas velocity, and Lyman-alpha properties
of candidates are consistent with their ISM being subject to more energetic
feedback than non-candidates. Together with their larger metallicity (implying
more evolved star-formation activity) this leads us to propose, if
speculatively, that they are likely to quench sooner than non-candidates,
supporting the validity of selection criteria used to identify them as
progenitors of z~2 passive galaxies. We propose that massive, compact galaxies
undergo more rapid growth of stellar mass content, perhaps because the gas
accretion mechanisms are different, and quench sooner than normally-sized LBGs
at these early epochs.Comment: Accepted for publication in the Astrophysical Journa
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