3,805 research outputs found
A multi-method approach to delineate and validate migratory corridors
Context:
Managers are faced with numerous methods for delineating wildlife movement corridors, and often must make decisions with limited data. Delineated corridors should be robust to different data and models.
Objectives:
We present a multi-method approach for delineating and validating wildlife corridors using multiple data sources, which can be used conserve landscape connectivity. We used this approach to delineate and validate migration corridors for wildebeest (Connochaetes taurinus) in the Tarangire Ecosystem of northern Tanzania.
Methods:
We used two types of locational data (distance sampling detections and GPS collar locations), and three modeling methods (negative binomial regression, logistic regression, and Maxent), to generate resource selection functions (RSFs) and define resistance surfaces. We compared two corridor detection algorithms (cost-distance and circuit theory), to delineate corridors. We validated corridors by comparing random and wildebeest locations that fell within corridors, and cross-validated by data type.
Results:
Both data types produced similar RSFs. Wildebeest consistently selected migration habitat in flatter terrain farther from human settlements. Validation indicated three of the combinations of data type, modeling, and corridor detection algorithms (detection data with Maxent modeling, GPS collar data with logistic regression modeling, and GPS collar data with Maxent modeling, all using cost-distance) far outperformed the other seven. We merged the predictive corridors from these three data-method combinations to reveal habitat with highest probability of use.
Conclusions:
The use of multiple methods ensures that planning is able to prioritize conservation of migration corridors based on all available information
Effect of Differential Rotation on the Maximum Mass of Neutron Stars: Realistic Nuclear Equations of State
The merger of binary neutron stars is likely to lead to differentially
rotating remnants. In this paper, we survey several cold nuclear equations of
state (EOSs) and numerically construct models of differentially rotating
neutron stars in general relativity. For each EOS we tabulate maximum allowed
masses as a function of the degree of differential rotation. We also determine
effective polytropic indices, and compare the maximum allowed masses with those
for the corresponding polytropes. We consistently find larger mass increases
for the polytropes, but even for the nuclear EOSs we typically find maximum
masses 50% higher than the corresponding values for nonrotating (TOV) stars. We
evaluate our findings for the six observed binary neutron star (pulsar)
systems, including the recently discovered binary pulsar J0737-3039. For each
EOS we determine whether their merger will automatically lead to prompt
collapse to a black hole, or whether the remnant can be supported against
collapse by uniform rotation (possibly as a supramassive star) or differential
rotation (possibly as a hypermassive star). For hypermassive stars, delayed
collapse to a black hole is likely. For the most recent EOSs we survey the
merger remnants can all be supported by rotation against prompt collapse, but
their actual fate will depend on the nonequilibrium dynamics of the coalescence
event. Gravitational wave observations of coalescing binary neutron stars may
be able to distinguish these outcomes -- no, delayed or prompt collapse -- and
thereby constrain possible EOSs.Comment: 8 pages, 3 figures, submitted to Ap
Findings from a pilot randomised trial of an asthma internet self-management intervention (RAISIN)
<b>Objective </b>To evaluate the feasibility of a phase 3
randomised controlled trial (RCT) of a website (Living
Well with Asthma) to support self-management.<p></p>
<b>Design and setting</b> Phase 2, parallel group, RCT,
participants recruited from 20 general practices across
Glasgow, UK. Randomisation through automated voice
response, after baseline data collection, to website
access for minimum 12 weeks or usual care.<p></p>
<b>Participants </b>Adults (age≥16 years) with physician
diagnosed, symptomatic asthma (Asthma Control
Questionnaire (ACQ) score ≥1). People with unstable
asthma or other lung disease were excluded.<p></p>
<b>Intervention</b> Living Well with Asthma’ is a desktop/
laptop compatible interactive website designed with
input from asthma/ behaviour change specialists, and
adults with asthma. It aims to support optimal
medication management, promote use of action plans,
encourage attendance at asthma reviews and increase
physical activity.<p></p>
<b>Outcome measures</b> Primary outcomes were
recruitment/retention, website use, ACQ and mini-
Asthma Quality of Life Questionnaire (AQLQ).
Secondary outcomes included patient activation,
prescribing, adherence, spirometry, lung inflammation
and health service contacts after 12 weeks. Blinding
postrandomisation was not possible.<p></p>
<b>Results </b>Recruitment target met. 51 participants
randomised (25 intervention group). Age range
16–78 years; 75% female; 28% from most deprived
quintile. 45/51 (88%; 20 intervention group) followed
up. 19 (76% of the intervention group) used the
website, for a mean of 18 min (range 0–49). 17 went
beyond the 2 ‘core’ modules. Median number of logins
was 1 (IQR 1–2, range 0–7). No significant difference
in the prespecified primary efficacy measures of ACQ
scores (−0.36; 95% CI −0.96 to 0.23; p=0.225), and
mini-AQLQ scores (0.38; −0.13 to 0.89; p=0.136). No
adverse events.<p></p>
<b>Conclusions</b> Recruitment and retention confirmed
feasibility; trends to improved outcomes suggest use of
Living Well with Asthma may improve self-management
in adults with asthma and merits further development
followed by investigation in a phase 3 trial
Segregation and linkage analysis for longitudinal measurements of a quantitative trait
We present a method for using slopes and intercepts from a linear regression of a quantitative trait as outcomes in segregation and linkage analyses. We apply the method to the analysis of longitudinal systolic blood pressure (SBP) data from the Framingham Heart Study. A first-stage linear model was fit to each subject's SBP measurements to estimate both their slope over time and an intercept, the latter scaled to represent the mean SBP at the average observed age (53.7 years). The subject-specific intercepts and slopes were then analyzed using segregation and linkage analysis. We describe a method for using the standard errors of the first-stage intercepts and slopes as weights in the genetic analyses. For the intercepts, we found significant evidence of a Mendelian gene in segregation analysis and suggestive linkage results (with LOD scores ≥ 1.5) for specific markers on chromosomes 1, 3, 5, 9, 10, and 17. For the slopes, however, the data did not support a Mendelian model, and thus no formal linkage analyses were conducted
Practical thermodynamics of Yukawa systems at strong coupling
Simple practical approach to estimate thermodynamic properties of strongly
coupled Yukawa systems, in both fluid and solid phases, is presented. The
accuracy of the approach is tested by extensive comparison with direct computer
simulation results (for fluids and solids) and the recently proposed
shortest-graph method (for solids). Possible applications to other systems of
softly repulsive particles are briefly discussed.Comment: Published in J. Chem. Phy
Second Generation International Space Station (ISS) Total Organic Carbon Analyzer (TOCA) Verification Testing and On-Orbit Performance Results
The Total Organic Carbon Analyzer (TOGA) is designed to autonomously determine recovered water quality as a function of TOC. The current TOGA has been on the International Space Station since November 2008. Functional checkout and operations revealed complex operating considerations. Specifically, failure of the hydrogen catalyst resulted in the development of an innovative oxidation analysis method. This method reduces the activation time and limits the hydrogen produced during analysis, while retaining the ability to indicate TOC concentrations within 25% accuracy. Subsequent testing and comparison to archived samples returned from the Station and tested on the ground yield high confidence in this method, and in the quality of the recovered water
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