7,717 research outputs found
Fibrous Foreign Body Obstruction of the Small Colon in Young Horses
During a 2 year period, 2 horses from the same farm were admitted to the Iowa State University Large Animal Hospital exhibiting signs of mild to moderate abdominal pain. Upon surgical exploration both horses were found to have a fibrous foreign body obstruction of the small colon. Intestinal resection and anastomosis successfully relieved the obstruction in both cases. It was determined that both obstructions were composed of synthetic fencing material
Relationship between cardiovascular risk and lipid testing in one health care system: a retrospective cohort study.
BackgroundThe US Preventive Services Taskforce (USPSTF) recommends routine lipid screening beginning age 35 for men [1]. For women age 20 and older, as well as men age 20-34, screening is recommended if cardiovascular risk factors are present. Prior research has focused on underutilization but not overuse of lipid testing. The objective is to document over- and under-use of lipid testing in an insured population of persons at low, moderate and high cardiovascular disease (CVD) risk for persons not already on statins.MethodsThe study is a retrospective cohort study that included all adults without prior CVD who were continuously enrolled in a large integrated healthcare system from 2005 to 2010. Measures included lipid test frequency extracted from administrative data and Framingham cardiovascular risk equations applied using electronic medical record data. Five year lipid testing patterns were examined by age, sex and CVD risk. Generalized linear models were used to estimate the relative risk for over testing associated with patient characteristics.ResultsAmong males and females for whom testing is not recommended, 35.8 % and 61.5 % received at least one lipid test in the prior 5 years and 8.4 % and 24.4 % had two or more. Over-testing was associated with age, race, comorbidity, primary care use and neighborhood income. Among individuals at moderate and high-risk (not already treated with statins) and for whom screening is recommended, between 21.4 % and 25.1 % of individuals received no screening in the prior 5 years.ConclusionsBased on USPSTF lipid screening recommendations, this study documents substantial over-testing among individuals with low CVD risk and under-testing among individuals with moderate to high-risk not already on statins. Opportunity exists to better focus lipid screening efforts appropriate to CVD risk
Symmetries of Differential Equations via Cartan's Method of Equivalence
We formulate a method of computing invariant 1-forms and structure equations
of symmetry pseudo-groups of differential equations based on Cartan's method of
equivalence and the moving coframe method introduced by Fels and Olver. Our
apparoach does not require a preliminary computation of infinitesimal defining
systems, their analysis and integration, and uses differentiation and linear
algebra operations only. Examples of its applications are given.Comment: 15 pages, LaTeX 2.0
Including debris cover effects in a distributed model of glacier ablation
Distributed glacier melt models generally assume that the glacier surface consists of bare exposed ice and snow. In reality, many glaciers are wholly or partially covered in layers of debris that tend to suppress ablation rates. In this paper, an existing physically based point model for the ablation of debris-covered ice is incorporated in a distributed melt model and applied to Haut Glacier dâArolla, Switzerland, which has three large patches of debris cover on its surface. The model is based on a 10 m resolution digital elevation model (DEM) of the area; each glacier pixel in the DEM is defined as either bare or debris-covered ice, and may be covered in snow that must be melted off before ice ablation is assumed to occur. Each debris-covered pixel is assigned a debris thickness value using probability distributions based on over 1000 manual thickness measurements. Locally observed meteorological data are used to run energy balance calculations in every pixel, using an approach suitable for snow, bare ice or debris-covered ice as appropriate. The use of the debris model significantly reduces the total ablation in the debris-covered areas, however the precise reduction is sensitive to the temperature extrapolation used in the model distribution because air near the debris surface tends to be slightly warmer than over bare ice. Overall results suggest that the debris patches, which cover 10% of the glacierized area, reduce total runoff from the glacierized part of the basin by up to 7%
The ACS Survey of Galactic Globular Clusters. III. The Double Subgiant Branch of NGC 1851
Photometry with HST's ACS reveals that the subgiant branch (SGB) of the
globular cluster NGC 1851 splits into two well-defined branches. If the split
is due only to an age effect, the two SGBs would imply two star formation
episodes separated by 1 Gyr. We discuss other anomalies in NGC 1851
which could be interpreted in terms of a double stellar population. Finally, we
compare the case of NGC 1851 with the other two globulars known to host
multiple stellar populations, and show that all three clusters differ in
several important respects.Comment: 22 pages, 7 figures, accepted for pubblication on Ap
Blaming Bill Gates AGAIN! Misuse, overuse and misunderstanding of performance data in sport
Recently in Sport, Education and Society, Williams and Manley (2014) argued against the heavy reliance on technology in professional Rugby Union and elite sport in general. In summary, technology is presented as an elitist, âgold standardâ villain that management and coaches use to exert control and by which players lose autonomy, identity, motivation, social interactions and expertise. In this article we suggest that the sociological interpretations and implications offered by Williams and Manley may be somewhat limited when viewed in isolation. In doing so, we identify some core methodological issues in Williams and Manleyâs study and critically consider important arguments for utilising technology; notably, to inform coach decision making and generate player empowerment. Secondly, we present a different, yet perhaps equally concerning, practice-oriented interpretation of the same results but from alternative coaching and expertise literature. Accordingly, we suggest that Williams and Manley have perhaps raised their alarm prematurely, inappropriately and on somewhat shaky foundations. We also hope to stimulate others to consider contrary positions, or at least to think about this topic in greater detail. More specifically, we encourage coaches and academics to think carefully about what technology is employed, how and why, and then the means by which these decisions are discussed with and, preferably, sold to players. Certainly, technology can significantly enhance coach decision making and practice, while also helping players to optimise their focus, empowerment and independence in knowing how to achieve their personal and collective goals
Peaks in the Hartle-Hawking Wave Function from Sums over Topologies
Recent developments in ``Einstein Dehn filling'' allow the construction of
infinitely many Einstein manifolds that have different topologies but are
geometrically close to each other. Using these results, we show that for many
spatial topologies, the Hartle-Hawking wave function for a spacetime with a
negative cosmological constant develops sharp peaks at certain calculable
geometries. The peaks we find are all centered on spatial metrics of constant
negative curvature, suggesting a new mechanism for obtaining local homogeneity
in quantum cosmology.Comment: 16 pages,LaTeX, no figures; v2: some changes coming from revision of
a math reference: wave function peaks sharp but not infinite; v3: added
paragraph in intro on interpretation of wave functio
Deep ACS Imaging in the Globular Cluster NGC 6397: The Cluster Color Magnitude Diagram and Luminosity Function
We present the CMD from deep HST imaging in the globular cluster NGC 6397.
The ACS was used for 126 orbits to image a single field in two colors (F814W,
F606W) 5 arcmin SE of the cluster center. The field observed overlaps that of
archival WFPC2 data from 1994 and 1997 which were used to proper motion (PM)
clean the data. Applying the PM corrections produces a remarkably clean CMD
which reveals a number of features never seen before in a globular cluster CMD.
In our field, the main sequence stars appeared to terminate close to the
location in the CMD of the hydrogen-burning limit predicted by two independent
sets of stellar evolution models. The faintest observed main sequence stars are
about a magnitude fainter than the least luminous metal-poor field halo stars
known, suggesting that the lowest luminosity halo stars still await discovery.
At the bright end the data extend beyond the main sequence turnoff to well up
the giant branch. A populous white dwarf cooling sequence is also seen in the
cluster CMD. The most dramatic features of the cooling sequence are its turn to
the blue at faint magnitudes as well as an apparent truncation near F814W = 28.
The cluster luminosity and mass functions were derived, stretching from the
turn off down to the hydrogen-burning limit. It was well modeled with either a
very flat power-law or a lognormal function. In order to interpret these fits
more fully we compared them with similar functions in the cluster core and with
a full N-body model of NGC 6397 finding satisfactory agreement between the
model predictions and the data. This exercise demonstrates the important role
and the effect that dynamics has played in altering the cluster IMF.Comment: 43 pages including 4 tables and 12 diagrams. Figures 2 and 3 have
been bitmapped. Accepted for publication in the Astronomical Journa
The ACS Survey of Galactic Globular Clusters. XII. Photometric Binaries along the Main-Sequence
The fraction of binary stars is an important ingredient to interpret globular
cluster dynamical evolution and their stellar population. We investigate the
properties of main-sequence binaries measured in a uniform photometric sample
of 59 Galactic globular clusters that were observed by HST WFC/ACS as a part of
the Globular Cluster Treasury project. We measured the fraction of binaries and
the distribution of mass-ratio as a function of radial location within the
cluster, from the central core to beyond the half-mass radius. We studied the
radial distribution of binary stars, and the distribution of stellar mass
ratios. We investigated monovariate relations between the fraction of binaries
and the main parameters of their host clusters. We found that in nearly all the
clusters, the total fraction of binaries is significantly smaller than the
fraction of binaries in the field, with a few exceptions only. Binary stars are
significantly more centrally concentrated than single MS stars in most of the
clusters studied in this paper. The distribution of the mass ratio is generally
flat (for mass-ratio parameter q>0.5). We found a significant anti-correlation
between the binary fraction in a cluster and its absolute luminosity (mass).
Some, less significant correlation with the collisional parameter, the central
stellar density, and the central velocity dispersion are present. There is no
statistically significant relation between the binary fraction and other
cluster parameters. We confirm the correlation between the binary fraction and
the fraction of blue stragglers in the cluster.Comment: 43 Pages, 52 figures, accepted for publication in A&
The structure of the magnetic field in the massive star-forming region W75N
A debated topic in star formation theory is the role of magnetic fields
during the protostellar phase of high-mass stars. It is still unclear how
magnetic fields influence the formation and dynamics of massive disks and
outflows. Most current information on magnetic fields close to high-mass
protostars comes from polarized maser emissions, which allows us to investigate
the magnetic field on small scales by using very long-baseline interferometry.
The massive star-forming region W75N contains three radio continuum sources
(VLA1, VLA2, and VLA3), at three different evolutionary stages, and associated
masers, while a large-scale molecular bipolar outflow is also present. Very
recently, polarization observations of the 6.7 GHz methanol masers at
milliarsecond resolution have been able to probe the strength and structure of
the magnetic field over more than 2000 AU around VLA1. The magnetic field is
parallel to the outflow, suggesting that VLA1 is its powering source. The
observations of water masers at 22 GHz can give more information about the gas
dynamics and the magnetic fields around VLA1 and VLA2. The NRAO Very Long
Baseline Array was used to measure the linear polarization and the
Zeeman-splitting of the 22 GHz water masers in the star-forming region W75N. We
detected 124 water masers, 36 around VLA1 and 88 around VLA2 of W75N, which
indicate two different physical environments around the two sources, where VLA1
is in a more evolved state. The linear polarization of the masers confirms the
tightly ordered magnetic field around VLA1, which is aligned with the
large-scale molecular outflow, and also reveals an ordered magnetic field
around VLA2, which is not parallel to the outflow. [abridged]Comment: 11 pages, 5 figures, 2 Tables, accepted by Astronomy & Astrophysic
- âŠ