8,654 research outputs found
A Second Relativistic Mean Field and Virial Equation of State for Astrophysical Simulations
We generate a second equation of state (EOS) of nuclear matter for a wide
range of temperatures, densities, and proton fractions for use in supernovae,
neutron star mergers, and black hole formation simulations. We employ full
relativistic mean field (RMF) calculations for matter at intermediate density
and high density, and the Virial expansion of a non-ideal gas for matter at low
density. For this EOS we use the RMF effective interaction FSUGold, whereas our
earlier EOS was based on the RMF effective interaction NL3. The FSUGold
interaction has a lower pressure at high densities compared to the NL3
interaction. We calculate the resulting EOS at over 100,000 grid points in the
temperature range = 0 to 80 MeV, the density range = 10 to 1.6
fm, and the proton fraction range = 0 to 0.56. We then interpolate
these data points using a suitable scheme to generate a thermodynamically
consistent equation of state table on a finer grid. We discuss differences
between this EOS, our NL3 based EOS, and previous EOSs by Lattimer-Swesty and
H. Shen et al for the thermodynamic properties, composition, and neutron star
structure. The original FSUGold interaction produces an EOS, that we call
FSU1.7, that has a maximum neutron star mass of 1.7 solar masses. A
modification in the high density EOS is introduced to increase the maximum
neutron star mass to 2.1 solar masses and results in a slightly different EOS
that we call FSU2.1. The EOS tables for FSU1.7 and FSU2.1 are available for
download.Comment: updated version according to referee's comments. Phys. Rev. C in
pres
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Estimating drizzle drop size and precipitation rate using two-colour lidar measurements
A method to estimate the size and liquid water content of drizzle drops using lidar measurements at two wavelengths is described. The method exploits the differential absorption of infrared light by liquid water at 905 nm and 1.5 μm, which leads to a different backscatter cross section for water drops larger than ≈50 μm. The ratio of backscatter measured from drizzle samples below cloud base at these two wavelengths (the colour ratio) provides a measure of the median volume drop diameter D0. This is a strong effect: for D0=200 μm, a colour ratio of ≈6 dB is predicted. Once D0 is known, the measured backscatter at 905 nm can be used to calculate the liquid water content (LWC) and other moments of the drizzle drop distribution.
The method is applied to observations of drizzle falling from stratocumulus and stratus clouds. High resolution (32 s, 36 m) profiles of D0, LWC and precipitation rate R are derived. The main sources of error in the technique are the need to assume a value for the dispersion parameter μ in the drop size spectrum (leading to at most a 35% error in R) and the influence of aerosol returns on the retrieval (≈10% error in R for the cases considered here). Radar reflectivities are also computed from the lidar data, and compared to independent measurements from a colocated cloud radar, offering independent validation of the derived drop size distributions
Neutrino Breakup of A=3 Nuclei in Supernovae
We extend the virial equation of state to include 3H and 3He nuclei, and
predict significant mass-three fractions near the neutrinosphere in supernovae.
While alpha particles are often more abundant, we demonstrate that energy
transfer cross-sections for muon and tau neutrinos at low densities are
dominated by breakup of the loosely-bound 3H and 3He nuclei. The virial
coefficients involving A=3 nuclei are calculated directly from the
corresponding nucleon-3H and nucleon-3He scattering phase shifts. For the
neutral-current inelastic cross-sections and the energy transfer cross
sections, we perform ab-initio calculations based on microscopic two- and
three-nucleon interactions and meson-exchange currents.Comment: 6 pages, 2 figures, minor additions, to appear in Phys. Rev.
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Developing theory-informed interventions to implement evidence into practice: a systematic approach using the Theoretical Domains Framework
Background: There is little systematic operational guidance about how best to develop complex interventions to reduce the gap between practice and evidence. This article is one in a series of articles documenting the development and use of the Theoretical Domains Framework (TDF) to advance the science of implementation research.
Methods: The intervention was developed considering three main components: theory, evidence, and practical issues. We used a four-step approach, consisting of guiding questions, to direct the choice of the most appropriate components of an implementation intervention: Who needs to do what, differently? Using a theoretical framework, which barriers and enablers need to be addressed? Which intervention components (behaviour change techniques and mode(s) of delivery) could overcome the modifiable barriers and enhance the enablers? And how can behaviour change be measured and understood?
Results: A complex implementation intervention was designed that aimed to improve acute low back pain management in primary care. We used the TDF to identify the barriers and enablers to the uptake of evidence into practice and to guide the choice of intervention components. These components were then combined into a cohesive intervention. The intervention was delivered via two facilitated interactive small group workshops. We also produced a DVD to distribute to all participants in the intervention group. We chose outcome measures in order to assess the mediating mechanisms of behaviour change.
Conclusions: We have illustrated a four-step systematic method for developing an intervention designed to change clinical practice based on a theoretical framework. The method of development provides a systematic framework that could be used by others developing complex implementation interventions. While this framework should be iteratively adjusted and refined to suit other contexts and settings, we believe that the four-step process should be maintained as the primary framework to guide researchers through a comprehensive intervention development process
Dimensional Crossover in the Large N Limit
We consider dimensional crossover for an Landau-Ginzburg-Wilson model
on a -dimensional film geometry of thickness in the large -limit. We
calculate the full universal crossover scaling forms for the free energy and
the equation of state. We compare the results obtained using ``environmentally
friendly'' renormalization with those found using a direct, non-renormalization
group approach. A set of effective critical exponents are calculated and
scaling laws for these exponents are shown to hold exactly, thereby yielding
non-trivial relations between the various thermodynamic scaling functions.Comment: 25 pages of PlainTe
Transfer Learning for Multi-language Twitter Election Classification
Both politicians and citizens are increasingly embracing social media as a means to disseminate information and comment on various topics, particularly during significant political events, such as elections. Such commentary during elections is also of interest to social scientists and pollsters. To facilitate the study of social media during elections, there is a need to automatically identify posts that are topically related to those elections. However, current studies have focused on elections within English-speaking regions, and hence the resultant election content classifiers are only applicable for elections in countries where the predominant language is English. On the other hand, as social media is becoming more prevalent worldwide, there is an increasing need for election classifiers that can be generalised across different languages, without building a training dataset for each election. In this paper, based upon transfer learning, we study the development of effective and reusable election classifiers for use on social media across multiple languages. We combine transfer learning with different classifiers such as Support Vector Machines (SVM) and state-of-the-art Convolutional Neural Networks (CNN), which make use of word embedding representations for each social media post. We generalise the learned classifier models for cross-language classification by using a linear translation approach to map the word embedding vectors from one language into another. Experiments conducted over two election datasets in different languages show that without using any training data from the target language, linear translations outperform a classical transfer learning approach, namely Transfer Component Analysis (TCA), by 80% in recall and 25% in F1 measure
The Sero-prevalence of Salmonella spp. in Finishing Swine in Iowa
This study represents the first attempt to classify Iowa production sites for Salmonella spp. sero-prevalence. The data suggest that the Iowa herds are similar in their distribution with respect to sero-prevalence of salmonella as Danish herds. Ignoring herd size, 91.2 of surveyed herds were negative or level 1, 8.2 % were level 2 herds, and 1.6 % level 3. These results are similar to previous Danish studies (Alban et al., 2002, Mousing et al., 1997). The current data suggests that larger herds tend to have a higher sero-prevalence than smaller units; however, formal analysis has yet to be conducted to determine the direct association between herd size and salmonella sero-prevalence. Studies by Carstensen et al. (1998) suggested that herd size was statistically associated, albeit weakly, with Salmonella sero-prevalence, but the authors concluded the relationship was probably not biologically significant
Determination of Toxoplasma gondii Antibody Prevalence in Midwest Market Swine
Pork has been identified as one of the food source(s) for human exposure to Toxoplasma gondii. This project was designed to determine the current prevalence of Toxoplasma gondii antibodies in the Midwestern USA market swine population. Test samples were selected, using random numbers generated from the Excel database, from approximately 2,500 daily meat juice samples submitted for Aujeszky’s Disease from eight Iowa abattoirs. Producer identification and lot size were recorded for each lot. Two hundred fifty samples were selected for 12 consecutive weeks – total of 15,014 samples. The presence of antibodies was determined using ELISA test kits by Safepath Laboratories. The prevalence for all samples was 0.75 % with a higher prevalence found in lots of 20 - 40 compared to 150 - 190 head. Additional on-farm evaluations of exposure risk factors are required to determine an association between sero-prevalence and lot size and to develop suitable prevention strategies
The Specific Heat of a Ferromagnetic Film.
We analyze the specific heat for the vector model on a -dimensional
film geometry of thickness using ``environmentally friendly''
renormalization. We consider periodic, Dirichlet and antiperiodic boundary
conditions, deriving expressions for the specific heat and an effective
specific heat exponent, \alpha\ef. In the case of , for , by
matching to the exact exponent of the two dimensional Ising model we capture
the crossover for \xi_L\ra\infty between power law behaviour in the limit
{L\over\xi_L}\ra\infty and logarithmic behaviour in the limit
{L\over\xi_L}\ra0 for fixed , where is the correlation length in
the transverse dimensions.Comment: 21 pages of Plain TeX. Postscript figures available upon request from
[email protected]
Modular Invariance of Finite Size Corrections and a Vortex Critical Phase
We analyze a continuous spin Gaussian model on a toroidal triangular lattice
with periods and where the spins carry a representation of the
fundamental group of the torus labeled by phases and . We find the
{\it exact finite size and lattice corrections}, to the partition function ,
for arbitrary mass and phases . Summing over phases gives
the corresponding result for the Ising model. The limits and
do not commute. With the model exhibits a {\it vortex
critical phase} when at least one of the is non-zero. In the continuum or
scaling limit, for arbitrary , the finite size corrections to are
{\it modular invariant} and for the critical phase are given by elliptic theta
functions. In the cylinder limit the ``cylinder charge''
is a non-monotonic function of that ranges from
for to zero for .Comment: 12 pages of Plain TeX with two postscript figure insertions called
torusfg1.ps and torusfg2.ps which can be obtained upon request from
[email protected]
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