47,186 research outputs found
Non-Clinical Benefits of Evidence - Based Veterinary Medicine
<div><strong>Clinical bottom line</strong></div><ul><li>There are few studies addressing business benefits of EBVM.</li><li>While the need for a wider adoption of EBVM has been highlighted and linked to commercial benefits, further empirical studies are needed to identify and quantify such linkages.</li></ul><p><br /> <img src="https://www.veterinaryevidence.org/rcvskmod/icons/oa-icon.jpg" alt="Open Access" /> <img src="https://www.veterinaryevidence.org/rcvskmod/icons/pr-icon.jpg" alt="Peer Reviewed" /></p
Rapid rotation of a Bose-Einstein condensate in a harmonic plus quartic trap
A two-dimensional rapidly rotating Bose-Einstein condensate in an anharmonic
trap with quadratic and quartic radial confinement is studied analytically with
the Thomas-Fermi approximation and numerically with the full time-independent
Gross-Pitaevskii equation. The quartic trap potential allows the rotation speed
to exceed the radial harmonic frequency . In the regime
, the condensate contains a dense vortex array
(approximated as solid-body rotation for the analytical studies). At a critical
angular velocity , a central hole appears in the condensate.
Numerical studies confirm the predicted value of , even for
interaction parameters that are not in the Thomas-Fermi limit. The behavior is
also investigated at larger angular velocities, where the system is expected to
undergo a transition to a giant vortex (with pure irrotational flow).Comment: 14 pages, 5 figure
A design assessment of multiwall, metallic stand-off, and RSI reusable thermal protection systems including space shuttle application
The design and assessment of reusable surface insulation (RSI), metallic stand off and multiwall thermal protection systems (TPS) is discussed. Multiwall TPS is described in some detail, and analyses useful for design of multiwall are included. Results indicate that multiwall has the potential to satisfy the TPS design goals better than the other systems. The total mass of the stand-off TPS and of the metallic systems require less primary structure mass than the RSI system, since the nonbuckling skin criteria required for RSI may be removed. Continued development of multiwall TPS is required to verify its potential and to provide the necessary data base for design
The changes in chemical composition during development of the bovine nuchal ligament
Whole bovine nuchal ligaments, or portions thereof (in the case of commercially valuable animals), were obtained from 45 animals (28 fetal and 17 postnatal) ranging in age from 110 days of gestation to 10 yr. Insoluble elastin was quantitatively prepared from the fresh ligaments by extraction with hot alkali and by a combination of multiple extractions with alkaline buffer and then repeated autoclaving. When adult samples were examined, the yields of insoluble residue by these two methods were very similar, but with young fetal samples the second method gave significantly higher values, because of incomplete purification of the elastin residue. The changes in the concentration of collagen, alkali-insoluble elastin, and DNA have been examined. DNA concentration, and, thus, cell population density, fell progressively during the fetal period of development, to reach a steady value soon after birth. Collagen appeared in appreciable quantities before elastin, but its concentration was rapidly halved at about the time of birth. Insoluble elastin concentration was low until the end of the 7th fetal month, at which time it began to rise rapidly. The rate of increase in elastin concentration remained high throughout the next 10–12 wk, by which time the adult value had been reached. Quantitative studies, on the basis of the whole ligament, showed that the total cell content rises to a maximum at birth, but falls soon after to a level about half that at birth. Total collagen production and elastin deposition continue at a steady, maximal rate over the interval from 235 days of gestation to the end of the 1st postnatal month. It is concluded that the immediate postnatal period would be the most favorable phase in which to attempt the isolation of the soluble precursor elastin
Oscillations of a Bose-Einstein condensate rotating in a harmonic plus quartic trap
We study the normal modes of a two-dimensional rotating Bose-Einstein
condensate confined in a quadratic plus quartic trap. Hydrodynamic theory and
sum rules are used to derive analytical predictions for the collective
frequencies in the limit of high angular velocities, , where the vortex
lattice produced by the rotation exhibits an annular structure. We predict a
class of excitations with frequency in the rotating frame,
irrespective of the mode multipolarity , as well as a class of low energy
modes with frequency proportional to . The predictions are in good
agreement with results of numerical simulations based on the 2D
Gross-Pitaevskii equation. The same analysis is also carried out at even higher
angular velocities, where the system enters the giant vortex regime.Comment: 4 pages, 2 figure
Theoretical progress for the associated production of a Higgs boson with heavy quarks at hadron colliders
The production of a Higgs boson in association with a pair of top-antitop or
bottom-antibottom quarks plays a very important role at both the Tevatron and
the Large Hadron Collider. The theoretical prediction of the corresponding
cross sections has been improved by including the complete next-to-leading
order QCD corrections. After a brief introduction, we review the results
obtained for both the Tevatron and the Large Hadron Collider.Comment: 3 pages, 6 figures, uses svjour.cls. Talk given by L. Reina at the
HEP2003 Europhysics Conference in Aachen, Germany (EPS 2003), July 17-23,
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Assessing Descriptive Substance in Free-Text Collection-Level Metadata
Collection-level metadata has the potential to provide important information about the features and purpose of individual collections. This paper reports on a content analysis of collection records in an aggregation of cultural heritage collections. The findings show that the free-text Description field often provides more accurate and complete representation of subjects and object types than the specified fields. Properties such as importance, uniqueness, comprehensiveness, provenance, and creator are articulated, as well as other vital contextual information about the intentions of a collector and the value of a collection, as a whole, for scholarly users. The results demonstrate that the semantically rich free-text Description field is essential to understanding the context of collections in large aggregations and can serve as a source of data for enhancing and customizing controlled vocabulariesIMLS NLG Research and Demonstration grant LG-06-07-0020-07published or submitted for publicationis peer reviewe
ULAS J234311.93-005034.0: A gravitational lens system selected from UKIDSS and SDSS
We report the discovery of a new gravitational lens system. This object, ULAS
J234311.93-005034.0, is the first to be selected by using the new UKIRT
Infrared Deep Sky Survey (UKIDSS), together with the Sloan Digital Sky Survey
(SDSS). The ULAS J234311.93-005034.0 system contains a quasar at redshift 0.788
which is doubly imaged, with separation 1.4". The two quasar images have the
same redshift and similar, though not identical, spectra. The lensing galaxy is
detected by subtracting point-spread functions from R-band images taken with
the Keck telescope. The lensing galaxy can also be detected by subtracting the
spectra of the A and B images, since more of the galaxy light is likely to be
present in the latter. No redshift is determined from the galaxy, although the
shape of its spectrum suggests a redshift of about 0.3. The object's lens
status is secure, due to the identification of two objects with the same
redshift together with a lensing galaxy. Our imaging suggests that the lens is
found in a cluster environment, in which candidate arc-like structures, that
require confirmation, are visible in the vicinity. Further discoveries of
lenses from the UKIDSS survey are likely as part of this programme, due to the
depth of UKIDSS and its generally good seeing conditions.Comment: Accepted by MNRA
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