3,518 research outputs found
The Deuterium Abundance in the z=0.7 absorber towards QSO PG1718+4807
We report a further analysis of the ratio of deuterium to hydrogen (D/H)
using HST spectra of the z=0.701 Lyman limit system towards the QSO PG1718+481.
Initial analyses of this absorber found it gave a high D/H value, 1.8 - 3.1
\times 10^{-4} (Webb et al. 1998), inconsistent with several higher redshift
measurements. It is thus important to critically examine this measurement. By
analysing the velocity widths of the DI, HI and metal lines present in this
system, Kirkman et al. (2001) report that the additional absorption in the blue
wing of the lya line can not be DI, with a confidence level of 98%. Here we
present a more detailed analysis, taking into account possible wavelength
shifts between the three sets of HST spectra used in the analysis. We find that
the constraints on this system are not as strong as those claimed by Kirkman et
al. The discrepancy between the parameters of the blue wing absorption and the
parameters expected for DI is marginally worse than 1 sigma.
Tytler et al.(1999) commented on the first analysis of Webb et
al.(1997,1998), reporting the presence of a contaminating lower redshift Lyman
limit system, with log[N(HI)] = 16.7 at z=0.602, which biases the N(HI)
estimate for the main system. Here we show that this absorber actually has
log[N(HI)] < 14.6 and does not impact on the estimate of N(HI) in the system of
interest at z = 0.701.
The purpose of the present paper is to highlight important aspects of the
analysis which were not explored in previous studies, and hence help refine the
methods used in future analyses of D/H in quasar spectra.Comment: 11 pages, 9 figures. Accepted by MNRA
Realistic assumptions about spatial locations and clustering of premises matter for models of foot-and-mouth disease spread in the United States
Spatially explicit livestock disease models require demographic data for individual farms or premises. In the U.S., demographic data are only available aggregated at county or coarser scales, so disease models must rely on assumptions about how individual premises are distributed within counties. Here, we addressed the importance of realistic assumptions for this purpose. We compared modeling of foot and mouth disease (FMD) outbreaks using simple randomization of locations to premises configurations predicted by the Farm Location and Agricultural Production Simulator (FLAPS), which infers location based on features such as topography, land-cover, climate, and roads. We focused on three premises-level Susceptible-Exposed-Infectious-Removed models available from the literature, all using the same kernel approach but with different parameterizations and functional forms. By computing the basic reproductive number of the infection (R0) for both FLAPS and randomized configurations, we investigated how spatial locations and clustering of premises affects outbreak predictions. Further, we performed stochastic simulations to evaluate if identified differences were consistent for later stages of an outbreak. Using Ripley's K to quantify clustering, we found that FLAPS configurations were substantially more clustered at the scales relevant for the implemented models, leading to a higher frequency of nearby premises compared to randomized configurations. As a result, R0 was typically higher in FLAPS configurations, and the simulation study corroborated the pattern for later stages of outbreaks. Further, both R0 and simulations exhibited substantial spatial heterogeneity in terms of differences between configurations. Thus, using realistic assumptions when de-aggregating locations based on available data can have a pronounced effect on epidemiological predictions, affecting if, where, and to what extent FMD may invade the population. We conclude that methods such as FLAPS should be preferred over randomization approaches
Detection of a Substantial Molecular Gas Reservoir in a brightest cluster galaxy at z = 1.7
We report the detection of CO(2-1) emission coincident with the brightest
cluster galaxy (BCG) of the high-redshift galaxy cluster SpARCS1049+56, with
the Redshift Search Receiver (RSR) on the Large Millimetre Telescope (LMT). We
confirm a spectroscopic redshift for the gas of z = 1.7091+/-0.0004, which is
consistent with the systemic redshift of the cluster galaxies of z = 1.709. The
line is well-fit by a single component Gaussian with a RSR resolution-corrected
FWHM of 569+/-63 km/s. We see no evidence for multiple velocity components in
the gas, as might be expected from the multiple image components seen in
near-infrared imaging with the Hubble Space Telescope. We measure the
integrated flux of the line to be 3.6+/-0.3 Jy km/s and, using alpha_CO = 0.8
Msun (K km s^-1 pc^2)^-1 we estimate a total molecular gas mass of
1.1+/-0.1x10^11 Msun and a M_H2/M_star ~ 0.4. This is the largest gas reservoir
detected in a BCG above z > 1 to date. Given the infrared-estimated star
formation rate of 860+/-130 Msun/yr, this corresponds to a gas depletion
timescale of ~0.1Gyr. We discuss several possible mechanisms for depositing
such a large gas reservoir to the cluster center -- e.g., a cooling flow, a
major galaxy-galaxy merger or the stripping of gas from several galaxies -- but
conclude that these LMT data are not sufficient to differentiate between them.Comment: accepted for publication in ApJ Letter
Just What Is Christian Counseling Anyway?
Professional psychologists may be asked about Christian counseling services and wonder how to best respond. Given the diversity of methods and worldviews that might be considered Christian counseling, it is important for psychologists to understand some of the major approaches used. Biblical counseling, pastoral counseling, Christian psychology, Christian ministry, and other approaches are described briefly, and in each case implications for professional psychologists are offered. Collaborative efforts are likely to be productive when interacting with certified pastoral counselors and Christian psychologists, and ministry approaches may provide supplemental resources for psychotherapy with Christian clients. Ethical issues are considered, and a 5-step model for responding to questions about Christian counseling is offered
Prevalence and causes of prescribing errors: the prescribing outcomes for trainee doctors engaged in clinical training (PROTECT) study
Objectives
Study objectives were to investigate the prevalence and causes of prescribing errors amongst foundation doctors (i.e. junior doctors in their first (F1) or second (F2) year of post-graduate training), describe their knowledge and experience of prescribing errors, and explore their self-efficacy (i.e. confidence) in prescribing.
Method
A three-part mixed-methods design was used, comprising: prospective observational study; semi-structured interviews and cross-sectional survey. All doctors prescribing in eight purposively selected hospitals in Scotland participated. All foundation doctors throughout Scotland participated in the survey. The number of prescribing errors per patient, doctor, ward and hospital, perceived causes of errors and a measure of doctors' self-efficacy were established.
Results
4710 patient charts and 44,726 prescribed medicines were reviewed. There were 3364 errors, affecting 1700 (36.1%) charts (overall error rate: 7.5%; F1:7.4%; F2:8.6%; consultants:6.3%). Higher error rates were associated with : teaching hospitals (p<0.001), surgical (p = <0.001) or mixed wards (0.008) rather thanmedical ward, higher patient turnover wards (p<0.001), a greater number of prescribed medicines (p<0.001) and the months December and June (p<0.001). One hundred errors were discussed in 40 interviews. Error causation was multi-factorial; work environment and team factors were particularly noted. Of 548 completed questionnaires (national response rate of 35.4%), 508 (92.7% of respondents) reported errors, most of which (328 (64.6%) did not reach the patient. Pressure from other staff, workload and interruptions were cited as the main causes of errors. Foundation year 2 doctors reported greater confidence than year 1 doctors in deciding the most appropriate medication regimen.
Conclusions
Prescribing errors are frequent and of complex causation. Foundation doctors made more errors than other doctors, but undertook the majority of prescribing, making them a key target for intervention. Contributing causes included work environment, team, task, individual and patient factors. Further work is needed to develop and assess interventions that address these.</p
Primordial nucleosynthesis and hadronic decay of a massive particle with a relatively short lifetime
In this paper we consider the effects on big bang nucleosynthesis (BBN) of
the hadronic decay of a long-lived massive particle. If high-energy hadrons are
emitted near the BBN epoch ( -- ), they
extraordinarily inter-convert the background nucleons each other even after the
freeze-out time of the neutron to proton ratio. Then, produced light element
abundances are changed, and that may result in a significant discrepancy
between standard BBN and observations. Especially on the theoretical side, now
we can obtain a lot of experimental data of hadrons and simulate the hadronic
decay process executing the numerical code of the hadron fragmentation even in
the high energy region where we have no experimental data. Using the light
element abundances computed in the hadron-injection scenario, we derive a
constraint on properties of such a particle by comparing our theoretical
results with observations.Comment: 33 pages, 14 postscript figures, reference added, typo corrected, to
appear in Phys. Rev.
Effects of regional differences and demography in modelling foot-and-mouth disease in cattle at the national scale
Foot-and-mouth disease (FMD) is a fast-spreading viral infection that can produce large and costly outbreaks in livestock populations. Transmission occurs at multiple spatial scales, as can the actions used to control outbreaks. The US cattle industry is spatially expansive, with heterogeneous distributions of animals and infrastructure. We have developed a model that incorporates the effects of scale for both disease transmission and control actions, applied here in simulating FMD outbreaks in US cattle. We simulated infection initiating in each of the 3049 counties in the contiguous US, 100 times per county. When initial infection was located in specific regions, large outbreaks were more likely to occur, driven by infrastructure and other demographic attributes such as premises clustering and number of cattle on premises. Sensitivity analyses suggest these attributes had more impact on outbreak metrics than the ranges of estimated disease parameter values. Additionally, although shipping accounted for a small percentage of overall transmission, areas receiving the most animal shipments tended to have other attributes that increase the probability of large outbreaks. The importance of including spatial and demographic heterogeneity in modelling outbreak trajectories and control actions is illustrated by specific regions consistently producing larger outbreaks than others
Spatio-temporal patterns and characteristics of swine shipments in the U.S. based on Interstate Certificates of Veterinary Inspection
Domestic swine production in the United States is a critical economic and food security industry, yet there is currently no large-scale quantitative assessment of swine shipments available to support risk assessments. In this study, we provide a national-level characterization of the swine industry by quantifying the demographic (i.e. age, sex) patterns, spatio-temporal patterns, and the production diversity within swine shipments. We characterize annual networks of swine shipments using a 30% stratified sample of Interstate Certificates of Veterinary Inspection (ICVI), which are required for the interstate movement of agricultural animals. We used ICVIs in 2010 and 2011 from eight states that represent 36% of swine operations and 63% of the U.S. swine industry. Our analyses reflect an integrated and spatially structured industry with high levels of spatial heterogeneity. Most shipments carried young swine for feeding or breeding purposes and carried a median of 330 head (range: 1–6,500). Geographically, most shipments went to and were shipped from Iowa, Minnesota, and Nebraska. This work, therefore, suggests that although the swine industry is variable in terms of its size and type of swine, counties in states historically known for breeding and feeding operations are consistently more central to the shipment network
Polaritonics in complex structures: Confinement, bandgap materials, and coherent control
We report on the design, fabrication, and testing of ferroelectric patterned
materials in the guided-wave and polaritonic regime. We demonstrate their
functionality and exploit polariton confinement for amplification and coherent
control using temporal pulse shaping.Comment: 3 pages, 3 figures, presented in the 14th international conference on
ultrafast phenomenon in Niigita Japan on July 25, 200
Cosmological Deuterium Production in Non-Standard Scenarios
It is widely believed that the cosmic baryon density may be obtained by
inferring deuterium abundances in low-metallicity quasar absorption line
systems. The implicit assumptions which enter this argument are critically
assessed. In particular, the production of deuterium in non-standard Big Bang
nucleosynthesis scenarios, the putative production of deuterium in
astrophysical environments, and the possible destruction of deuterium via
non-standard chemical evolution are discussed.Comment: 11 pages, article based on a talk presented at "Deuterium in the
Universe", Meudon, June 2001, to be published in Planetary and Space Scienc
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