55 research outputs found
Four lectures on secant varieties
This paper is based on the first author's lectures at the 2012 University of
Regina Workshop "Connections Between Algebra and Geometry". Its aim is to
provide an introduction to the theory of higher secant varieties and their
applications. Several references and solved exercises are also included.Comment: Lectures notes to appear in PROMS (Springer Proceedings in
Mathematics & Statistics), Springer/Birkhause
Stroke in Patients With Acute Coronary Syndromes: Incidence and Outcomes in the Platelet Glycoprotein IIb/IIIa in Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT) Trial
BACKGROUND: The incidence of stroke in patients with acute coronary
syndromes has not been clearly defined because few trials in this patient
population have been large enough to provide stable estimates of stroke
rates. METHODS AND RESULTS: We studied the 10 948 patients with acute
coronary syndromes without persistent ST-segment elevation who were
randomly assigned to placebo or the platelet glycoprotein IIb/IIIa
receptor inhibitor eptifibatide in the Platelet Glycoprotein IIb/IIIa in
Unstable Angina: Receptor Suppression Using Integrilin Therapy (PURSUIT)
trial to determine stroke rates, stroke types, clinical outcomes in
patients with stroke, and independent baseline clinical predictors for
nonhemorrhagic stroke. Stroke occurred in 79 (0.7%) patients, with 66
(0.6%) nonhemorrhagic, 6 intracranial hemorrhages, 3 cerebral infarctions
with hemorrhagic conversion, and 4 of uncertain cause. There were no
differences in stroke rates between patients who received placebo and
those assigned high-dose eptifibatide (odds ratios and 95% confidence
intervals 0.82 [0.59, 1.14] and 0.70 [0.49, 0.99], respectively). Of the
79 patients with stroke, 17 (22%) died within 30 days, and another 26
(32%) were disabled by hospital discharge or 30 days, whichever came
first. Higher heart rate was the most important baseline clinical
predictor of nonhemorrhagic stroke, followed by older age, prior anterior
myocardial infarction, prior stroke or transient ischemic attack, and
diabetes mellitus. These factors were used to develop a simple scoring
nomogram that can predict the risk of nonhemorrhagic stroke. CONCLUSIONS:
Stro
The use of sewage treatment works as foraging sites by insectivorous bats
Sewage treatment works with percolating filter beds are known to provide profitable foraging areas for insectivorous birds due to their association with high macroinvertebrate densities. Fly larvae developing on filter beds at sewage treatment works may similarly provide a valuable resource for foraging bats. Over the last two decades, however, there has been a decline in filter beds towards a system of âactivated sludgeâ. Insects and bat activity were surveyed at 30 sites in Scotland employing these two different types of sewage treatment in order to assess the possible implications of these changes for foraging bats. Bat activity (number of passes) recorded from broad-band bat detectors was quantified at three points within each site. The biomass of aerial insects, sampled over the same period as the detector surveys, was measured using a suction trap. The biomass of insects and activity of Pipistrellus spp. was significantly higher at filter beds than at activated sludge sites. In addition, whilst foraging activity of Pipistrellus spp. at filter beds was comparable to that of adjacent âgoodâ foraging habitat, foraging at activated sludge sites was considerably lower. This study indicates the high potential value of an anthropogenic process to foraging bats, particularly in a landscape where their insect prey has undergone a marked decline, and suggests that the current preference for activated sludge systems is likely to reduce the value of treatment works as foraging sites for bats
Comprehensive analysis of epigenetic clocks reveals associations between disproportionate biological ageing and hippocampal volume
The concept of age acceleration, the difference between biological age and chronological age, is of growing interest, particularly with respect to age-related disorders, such as Alzheimerâs Disease (AD). Whilst studies have reported associations with AD risk and related phenotypes, there remains a lack of consensus on these associations. Here we aimed to comprehensively investigate the relationship between five recognised measures of age acceleration, based on DNA methylation patterns (DNAm age), and cross-sectional and longitudinal cognition and AD-related neuroimaging phenotypes (volumetric MRI and Amyloid-β PET) in the Australian Imaging, Biomarkers and Lifestyle (AIBL) and the Alzheimerâs Disease Neuroimaging Initiative (ADNI). Significant associations were observed between age acceleration using the Hannum epigenetic clock and cross-sectional hippocampal volume in AIBL and replicated in ADNI. In AIBL, several other findings were observed cross-sectionally, including a significant association between hippocampal volume and the Hannum and Phenoage epigenetic clocks. Further, significant associations were also observed between hippocampal volume and the Zhang and Phenoage epigenetic clocks within Amyloid-β positive individuals. However, these were not validated within the ADNI cohort. No associations between age acceleration and other Alzheimerâs disease-related phenotypes, including measures of cognition or brain Amyloid-β burden, were observed, and there was no association with longitudinal change in any phenotype. This study presents a link between age acceleration, as determined using DNA methylation, and hippocampal volume that was statistically significant across two highly characterised cohorts. The results presented in this study contribute to a growing literature that supports the role of epigenetic modifications in ageing and AD-related phenotypes
The production of nanometre structures in inorganic materials by electron beams of high current density
SIGLEAvailable from British Library Document Supply Centre- DSC:D60690 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
The production of nanometre structures in inorganic materials by electron beams of high current density
SIGLEAvailable from British Library Document Supply Centre- DSC:D60690 / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Comparisons among ten models of acoustic backscattering used in aquatic ecosystem research
The article of record may be found at http://dx.doi.org/10.1121/1.4937607Analytical and numerical scattering models with accompanying digital representations are used increasingly to predict acoustic backscatter by fish and zooplankton in research and ecosystem monitoring applications. Ten such models were applied to targets with simple geometric shapes and parameterized (e.g., size and material properties) to represent biological organisms such as zooplankton and fish, and their predictions of acoustic backscatter were compared to those from exact or approximate analytical models, i.e., benchmarks. These comparisons were made for a sphere, spherical shell, prolate spheroid, and finite cylinder, each with homogeneous composition. For each shape, four target boundary conditions were considered: rigid-fixed, pressure-release, gas-filled, and weakly scattering. Target strength (dB re 1 m2) was calculated as a function of insonifying frequency (f 1â4 12 to 400 kHz) and angle of incidence...This work was supported by the NOAA Fisheries Advanced Sampling Technologies Working Group, the Office of Naval Research, and the National Oceanic Partnership Progra
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