4,687 research outputs found
Ostracods from freshwater and brackish environments of the Carboniferous of the Midland Valley of Scotland : the early colonization of terrestrial water bodies
The Mississippian Strathclyde Group of the Midland Valley of Scotland yields some of the earliest non-marine ostracods. The succession records shallow marine, deltaic, estuarine, lagoonal, lacustrine, fluvial and swamp environments representing a series of staging-posts between fully marine and limnetic settings. Macrofossils and ostracods are assigned to marine, marginal marine, brackish and freshwater environments based on their faunal assemblage patterns. Key brackish to freshwater ostracods are Geisina arcuata, Paraparchites circularis n. sp., Shemonaella ornata n. sp. and Silenites sp. A, associated with the bivalves Anthraconaia, Carbonicola, Cardiopteridium, Curvirimula, Naiadites, the microconchid ‘Spirorbis’, Spinicaudata and fish. Many Platycopina and Paraparchiticopina ostracods are interpreted as euryhaline, which corresponds with their occurrence in marine to coastal plain water bodies, and supports the ‘estuary effect’ hypothesis of non-marine colonization. The success of non-marine colonization by ostracods was dependent on the intrinsic adaptations of ostracod species to lower salinities, such as new reproductive strategies and the timing of extrinsic mechanisms to drive non-marine colonization, such as sea-level change. The genus Carbonita is the oldest and most common freshwater ostracod, and went on to dominate freshwater environments in the Late Palaeozoic
Risk factors for chest infection in acute stroke: a prospective cohort study
<p><b>Background and Purpose:</b> Pneumonia is a major cause of morbidity and mortality after stroke. We aimed to determine key characteristics that would allow prediction of those patients who are at highest risk for poststroke pneumonia.</p>
<p><b>Methods:</b> We studied a series of consecutive patients with acute stroke who were admitted to hospital. Detailed evaluation included the modified National Institutes of Health Stroke Scale; the Abbreviated Mental Test; and measures of swallow, respiratory, and oral health status. Pneumonia was diagnosed by set criteria. Patients were followed up at 3 months after stroke.</p>
<p><b>Results:</b> We studied 412 patients, 391 (94.9%) with ischemic stroke and 21 (5.1%) with hemorrhagic stroke; 78 (18.9%) met the study criteria for pneumonia. Subjects who developed pneumonia were older (mean±SD age, 75.9±11.4 vs 64.9±13.9 years), had higher modified National Institutes of Health Stroke Scale scores, a history of chronic obstructive pulmonary disease, lower Abbreviated Mental Test scores, and a higher oral cavity score, and a greater proportion tested positive for bacterial cultures from oral swabs. In binary logistic-regression analysis, independent predictors (P<0.05) of pneumonia were age >65 years, dysarthria or no speech due to aphasia, a modified Rankin Scale score ≥4, an Abbreviated Mental Test score <8, and failure on the water swallow test. The presence of 2 or more of these risk factors carried 90.9% sensitivity and 75.6% specificity for the development of pneumonia.</p>
<p><b>Conclusions:</b> Pneumonia after stroke is associated with older age, dysarthria/no speech due to aphasia, severity of poststroke disability, cognitive impairment, and an abnormal water swallow test result. Simple assessment of these variables could be used to identify patients at high risk of developing pneumonia after stroke.</p>
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Rate inhibition of steam gasification by adsorbed hydrogen
In this twelfth quarter of the grant period, experiments have focused on the effects of char oxidation on gasification rate in steam/hydrogen mixtures. Experiments have been conducted primarily on annealed Saran char at temperatures of 1,000 K and 1,120 K, and the quantity of hydrogen adsorbed on the char surface both prior to and following oxidation has been measured. The paper discusses results on the stability of adsorbed oxygen groups on char surface and the rate enhancement via oxidation
An Ensemble Kalman-Particle Predictor-Corrector Filter for Non-Gaussian Data Assimilation
An Ensemble Kalman Filter (EnKF, the predictor) is used make a large change
in the state, followed by a Particle Filer (PF, the corrector) which assigns
importance weights to describe non-Gaussian distribution. The weights are
obtained by nonparametric density estimation. It is demonstrated on several
numerical examples that the new predictor-corrector filter combines the
advantages of the EnKF and the PF and that it is suitable for high dimensional
states which are discretizations of solutions of partial differential
equations.Comment: ICCS 2009, to appear; 9 pages; minor edit
Sympathetic Cooling of Trapped Cd+ Isotopes
We sympathetically cool a trapped 112Cd+ ion by directly Doppler-cooling a
114Cd+ ion in the same trap. This is the first demonstration of optically
addressing a single trapped ion being sympathetically cooled by a different
species ion. Notably, the experiment uses a single laser source, and does not
require strong focusing. This paves the way toward reducing decoherence in an
ion trap quantum computer based on Cd+ isotopes.Comment: 4 figure
Measuring the Spin of the Higgs Boson
By studying the threshold dependence of the excitation curve and the angular
distribution in Higgs-strahlung at e+e- colliders, e+e- -> HZ, the spin of the
Higgs boson in the Standard Model and related extensions can be determined
unambiguously in a model-independent way.Comment: 10 pages, 1 Postscript figure, sign typo correcte
Critical currents in Josephson junctions, with unconventional pairing symmetry: versus
Phenomenological Ginzburg-Landau theory is used to calculate the possible
spontaneous vortex states that may exist at corner junctions of
-wave, (where or ) and s-wave superconductors.
We study the magnetic flux and the critical current modulation with the
junction orientation angle , the magnitude of the order parameter, and
the magnetic field . It is seen that the critical current versus the
magnetic flux relation is symmetric / asymmetric for when
the orientation is exactly such that the lobes of the dominant
-wave order parameter points towards the two junctions, which are
at right angles for the corner junction. The conclusion is that a measurement
of the relation may distinguish which symmetry ( or
) the order parameter has.Comment: 11 pages with 11 figures, Changed conten
Self-generated magnetic flux in YBaCuO grain boundaries
Grain boundaries in YBaCuO superconducting films are
considered as Josephson junctions with a critical current density
alternating along the junction. A self-generated magnetic flux is treated both
analytically and numerically for an almost periodic distribution of .
We obtained a magnetic flux-pattern similar to the one which was recently
observed experimentally.Comment: 7 pages, 3 figure
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