2,469 research outputs found
The Impact of Weather on the Behavior and Ecology of Birds
Weather conditions affect animals in many different ways. Variation in temperature, rainfall, wind, and other environmental variables can have an impact at a range of temporal and spatial scales and at every level from individual behavior to species distributions. The interactions between these variables may be particularly important but are often overlooked. Hence, understanding how animals respond to weather conditions is a fundamental topic in evolution, ecology, and conservation, especially in a time of major environmental change.Birds are an ideal group in which to investigate these relationships because they occur in almost every ecosystem across the globe, exploit a wide variety of food resources and often move between vastly different environments during their annual life cycle. Most recent research has focused on the impact of climate change and extreme weather events, but even small-scale variation in weather conditions may influence avian behavior, life history, physiology, and morphology. Assessing how birds respond to variation in weather, and the fitness consequences this brings, therefore plays a crucial role in a number of active research areas, including:(1) identifying the selective pressures that may have led to trait evolution;(2) predicting how birds will respond to environmental change; and(3) developing successful conservation measures for threatened species.This timely Research Topic builds on the symposium The Effects of Weather on Birds held at the 2019 European Ornithologists’ Union Congress at Cluj-Napoca, Romania. It will bring together articles from a range of disciplines to offer valuable and synthesized insights into the relationship between weather and birds. In doing so, it will link together broader themes such as adaptation, phenotypic plasticity, life history evolution, population dynamics, and migration, while also increasing our knowledge on the potential impacts of climate change.We welcome contributions on any aspect of the weather and how it affects the behavior or ecology of birds. Articles may be original research papers, comparative analyses, reviews or perspectives
The L_X--M relation of Clusters of Galaxies
We present a new measurement of the scaling relation between X-ray luminosity
and total mass for 17,000 galaxy clusters in the maxBCG cluster sample.
Stacking sub-samples within fixed ranges of optical richness, N_200, we measure
the mean 0.1-2.4 keV X-ray luminosity, , from the ROSAT All-Sky Survey.
The mean mass, , is measured from weak gravitational lensing of SDSS
background galaxies (Johnston et al. 2007). For 9 <= N_200 < 200, the data are
well fit by a power-law, /10^42 h^-2 erg/s = (12.6+1.4-1.3 (stat) +/- 1.6
(sys)) (/10^14 h^-1 M_sun)^1.65+/-0.13. The slope agrees to within 10%
with previous estimates based on X-ray selected catalogs, implying that the
covariance in L_X and N_200 at fixed halo mass is not large. The luminosity
intercent is 30%, or 2\sigma, lower than determined from the X-ray flux-limited
sample of Reiprich & Bohringer (2002), assuming hydrostatic equilibrium. This
difference could arise from a combination of Malmquist bias and/or systematic
error in hydrostatic mass estimates, both of which are expected. The intercept
agrees with that derived by Stanek et al. (2006) using a model for the
statistical correspondence between clusters and halos in a WMAP3 cosmology with
power spectrum normalization sigma_8 = 0.85. Similar exercises applied to
future data sets will allow constraints on the covariance among optical and hot
gas properties of clusters at fixed mass.Comment: 5 pages, 1 figure, MNRAS accepte
Towards More Accurate Molecular Dynamics Calculation of Thermal Conductivity. Case Study: GaN Bulk Crystals
Significant differences exist among literature for thermal conductivity of
various systems computed using molecular dynamics simulation. In some cases,
unphysical results, for example, negative thermal conductivity, have been
found. Using GaN as an example case and the direct non-equilibrium method,
extensive molecular dynamics simulations and Monte Carlo analysis of the
results have been carried out to quantify the uncertainty level of the
molecular dynamics methods and to identify the conditions that can yield
sufficiently accurate calculations of thermal conductivity. We found that the
errors of the calculations are mainly due to the statistical thermal
fluctuations. Extrapolating results to the limit of an infinite-size system
tend to magnify the errors and occasionally lead to unphysical results. The
error in bulk estimates can be reduced by performing longer time averages using
properly selected systems over a range of sample lengths. If the errors in the
conductivity estimates associated with each of the sample lengths are kept
below a certain threshold, the likelihood of obtaining unphysical bulk values
becomes insignificant. Using a Monte-Carlo approach developed here, we have
determined the probability distributions for the bulk thermal conductivities
obtained using the direct method. We also have observed a nonlinear effect that
can become a source of significant errors. For the extremely accurate results
presented here, we predict a [0001] GaN thermal conductivity of 185 at 300 K, 102 at 500 K, and 74
at 800 K. Using the insights obtained in the work, we have achieved a
corresponding error level (standard deviation) for the bulk (infinite sample
length) GaN thermal conductivity of less than 10 , 5 , and 15 at 300 K, 500 K, and 800 K respectively
An Evolving Entropy Floor in the Intracluster Gas?
Non-gravitational processes, such as feedback from galaxies and their active
nuclei, are believed to have injected excess entropy into the intracluster gas,
and therefore to have modified the density profiles in galaxy clusters during
their formation. Here we study a simple model for this so-called preheating
scenario, and ask (i) whether it can simultaneously explain both global X-ray
scaling relations and number counts of galaxy clusters, and (ii) whether the
amount of entropy required evolves with redshift. We adopt a baseline entropy
profile that fits recent hydrodynamic simulations, modify the hydrostatic
equilibrium condition for the gas by including approx. 20% non-thermal pressure
support, and add an entropy floor K_0 that is allowed to vary with redshift. We
find that the observed luminosity-temperature (L-T) relations of low-redshift
(z=0.05) HIFLUGCS clusters and high-redshift (z=0.8) WARPS clusters are best
simultaneously reproduced with an evolving entropy floor of
K_0(z)=341(1+z)^{-0.83}h^{-1/3} keV cm^2. If we restrict our analysis to the
subset of bright (kT > 3 keV) clusters, we find that the evolving entropy floor
can mimic a self-similar evolution in the L-T scaling relation. This degeneracy
with self-similar evolution is, however, broken when (0.5 < kT < 3 keV)
clusters are also included. The approx. 60% entropy increase we find from z=0.8
to z=0.05 is roughly consistent with that expected if the heating is provided
by the evolving global quasar population. Using the cosmological parameters
from the WMAP 3-year data with sigma_8=0.76, our best-fit model underpredicts
the number counts of the X-ray galaxy clusters compared to those derived from
the 158 deg^2 ROSAT PSPC survey. Treating sigma_8 as a free parameter, we find
a best-fit value of sigma_8=0.80+/- 0.02.Comment: 14 emulateapj pages with 9 figures, submitted to Ap
The social value of a QALY : raising the bar or barring the raise?
Background: Since the inception of the National Institute for Health and Clinical Excellence (NICE) in England,
there have been questions about the empirical basis for the cost-per-QALY threshold used by NICE and whether
QALYs gained by different beneficiaries of health care should be weighted equally. The Social Value of a QALY
(SVQ) project, reported in this paper, was commissioned to address these two questions. The results of SVQ were
released during a time of considerable debate about the NICE threshold, and authors with differing perspectives
have drawn on the SVQ results to support their cases. As these discussions continue, and given the selective use of
results by those involved, it is important, therefore, not only to present a summary overview of SVQ, but also for
those who conducted the research to contribute to the debate as to its implications for NICE.
Discussion: The issue of the threshold was addressed in two ways: first, by combining, via a set of models, the
current UK Value of a Prevented Fatality (used in transport policy) with data on fatality age, life expectancy and
age-related quality of life; and, second, via a survey designed to test the feasibility of combining respondents’
answers to willingness to pay and health state utility questions to arrive at values of a QALY. Modelling resulted in
values of £10,000-£70,000 per QALY. Via survey research, most methods of aggregating the data resulted in values
of a QALY of £18,000-£40,000, although others resulted in implausibly high values. An additional survey, addressing
the issue of weighting QALYs, used two methods, one indicating that QALYs should not be weighted and the
other that greater weight could be given to QALYs gained by some groups.
Summary: Although we conducted only a feasibility study and a modelling exercise, neither present compelling
evidence for moving the NICE threshold up or down. Some preliminary evidence would indicate it could be
moved up for some types of QALY and down for others. While many members of the public appear to be open to
the possibility of using somewhat different QALY weights for different groups of beneficiaries, we do not yet have
any secure evidence base for introducing such a system
The equivalence of numbers: The social value of avoiding health decline: An experimental web-based study
BACKGROUND: Health economic analysis aimed at informing policy makers and supporting resource allocation decisions has to evaluate not only improvements in health but also avoided decline. Little is known however, whether the "direction" in which changes in health are experienced is important for the public in prioritizing among patients. This experimental study investigates the social value people place on avoiding (further) health decline when directly compared to curative treatments in resource allocation decisions. METHODS: 127 individuals completed an interactive survey that was published in the World Wide Web. They were confronted with a standard gamble (SG) and three person trade-off tasks, either comparing improvements in health (PTO-Up), avoided decline (PTO-Down), or both, contrasting health changes of equal magnitude differing in the direction in which they are experienced (PTO-WAD). Finally, a direct priority ranking of various interventions was obtained. RESULTS: Participants strongly prioritized improving patients' health rather than avoiding decline. The mean substitution rate between health improvements and avoided decline (WAD) ranged between 0.47 and 0.64 dependent on the intervention. Weighting PTO values according to the direction in which changes in health are experienced improved their accuracy in predicting a direct prioritization ranking. Health state utilities obtained by the standard gamble method seem not to reflect social values in resource allocation contexts. CONCLUSION: Results suggest that the utility of being cured of a given health state might not be a good approximation for the societal value of avoiding this health state, especially in cases of competition between preventive and curative interventions
Reliability of Fronto-Amygdala Coupling during Emotional Face Processing.
One of the most exciting translational prospects for brain imaging research is the potential use of functional magnetic resonance imaging (fMRI) 'biomarkers' to predict an individual's risk of developing a neuropsychiatric disorder or the likelihood of responding to a particular intervention. This proposal depends critically on reliable measurements at the level of the individual. Several previous studies have reported relatively poor reliability of amygdala activation during emotional face processing, a key putative fMRI 'biomarker'. However, the reliability of amygdala connectivity measures is much less well understood. Here, we assessed the reliability of task-modulated coupling between three seed regions (left and right amygdala and the subgenual anterior cingulate cortex) and the dorsomedial frontal/cingulate cortex (DMFC), measured using a psychophysiological interaction analysis in 29 healthy individuals scanned approximately two weeks apart. We performed two runs on each day of three different emotional face-processing tasks: emotion identification, emotion matching, and gender classification. We tested both between-day reliability and within-day (between-run) reliability. We found good-to-excellent within-subject reliability of amygdala-DMFC coupling, both between days (in two tasks), and within day (in one task). This suggests that disorder-relevant regional coupling may be sufficiently reliable to be used as a predictor of treatment response or clinical risk in future clinical studies
Ralph B. Stine and Margaret E. Stine v. Henry Girola and Diane Girola and State Underwriters, Inc. : Petition for Rehearing
In this paper we present a Remote Control Unit (RCU) that can be attached to any location on a rifle, binoculars, etc., and be operated by a single finger of a soldier without removing his hand from the device. Even for a gloved hand a haptic feedback from the RCU will be realized. A RCU prototype, equipped with a single button, is used as a remote Push-to-Talk (PTT) device for the radio being carried by the soldier. The RCU is powered by the radio waves emitted by this radio. The RCU - being attached to the device - works with a receive unit (RXU) that is attached to and operates the radio. The RCU consists of a RF harvester, energy storage device, a button and a transmitter. Laboratory prototypes are demonstrated
Exploring what lies behind public preferences for avoiding health losses caused by lapses in healthcare safety and patient lifestyle choices
© 2013 Singh et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.This article has been made available through the Brunel Open Access Publishing Fund.Background: Although many studies have identified public preferences for prioritising health care interventions based on characteristics of recipient or care, very few of them have examined the reasons for the stated preferences. We conducted an on-line person trade-off (PTO) study (N=1030) to investigate whether the public attach a premium to the avoidance of ill health associated with alternative types of responsibilities: lapses in healthcare safety, those caused by individual action or lifestyle choice; or genetic conditions. We found that the public gave higher priority to prevention of harm in a hospital setting such as preventing hospital associated infections than genetic disorder but drug administration errors were valued similar to genetic disorders. Prevention of staff injuries, lifestyle diseases and sports injuries, were given lower priority. In this paper we aim to understand the reasoning behind the responses by analysing comments provided by respondents to the PTO questions. Method: A majority of the respondents who participated in the survey provided brief comments explaining preferences in free text responses following PTO questions. This qualitative data was transformed into explicit codes conveying similar meanings. An overall coding framework was developed and a reliability test was carried out. Recurrent patterns were identified in each preference group. Comments which challenged the assumptions of hypothetical scenarios were also investigated. Results: NHS causation of illness and a duty of care were the most cited reasons to prioritise lapses in healthcare safety. Personal responsibility dominated responses for lifestyle related contexts, and many respondents mentioned that health loss was the result of the individual’s choice to engage in risky behaviour. A small proportion of responses questioned the assumptions underlying the PTO questions. However excluding these from the main analysis did not affect the conclusions.
Conclusion: Although some responses indicated misunderstanding or rejection of assumptions we put forward, the results were still robust. The reasons put forward for responses differed between comparisons but responsibility was the most frequently cited. Most preference elicitation studies only focus on eliciting numerical valuations but allowing for qualitative data can augment understanding of preferences as well as verifying results.EPSRC through the MATCH programme(EP/F063822/1 and EP/G012393/1) and HERG within Brunel University
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