1,223 research outputs found
Deformation spaces of Kleinian surface groups are not locally connected
For any closed surface of genus , we show that the deformation
space of marked hyperbolic 3-manifolds homotopy equivalent to , , is not locally connected. This proves a conjecture of Bromberg who
recently proved that the space of Kleinian punctured torus groups is not
locally connected. Playing an essential role in our proof is a new version of
the filling theorem that is based on the theory of cone-manifold deformations
developed by Hodgson, Kerckhoff, and Bromberg
Tannakian duality for Anderson-Drinfeld motives and algebraic independence of Carlitz logarithms
We develop a theory of Tannakian Galois groups for t-motives and relate this
to the theory of Frobenius semilinear difference equations. We show that the
transcendence degree of the period matrix associated to a given t-motive is
equal to the dimension of its Galois group. Using this result we prove that
Carlitz logarithms of algebraic functions that are linearly independent over
the rational function field are algebraically independent.Comment: 39 page
Facile access to a heterocyclic, sp3-rich chemical scaffold via a tandem condensation/intramolecular nitrone–alkene [3+2] cycloaddition strategy
A heterocyclic, sp3-rich chemical scaffold was synthesised in just 6 steps via a highly regio- and diastereo-selective tandem nitrone formation/intramolecular nitrone–alkene [3+2] cycloaddition reaction. A library of 543 lead-like compounds based on the scaffold core has been produced
Executive summary: heart disease and stroke statistics--2013 update: a report from the American Heart Association.
Each year, the American Heart Association (AHA), in conjunction with the Centers for Disease Control and Prevention, the National Institutes of Health, and other government agencies, brings together the most up-to-date statistics on heart disease, stroke, other vascular diseases, and their risk factors and presents them in its Heart Disease and Stroke Statistical Update*The Statistical Update is a valuable resource for researchers, clinicians, healthcare policy makers, media professionals, the lay public, and many others who seek the best national data available on heart disease, stroke, and other cardiovascular disease-related morbidity and mortality and the risks, quality of care, medical procedures and operations, and costs associated with the management of these diseases in a single document*Indeed, since 1999, the Statistical Update has been cited \u3e10 500 times in the literature, based on citations of all annual versions*In 2011 alone, the various Statistical Updates were cited ≈1500 times (data from ISI Web of Science)*In recent years, the Statistical Update has undergone some major changes with the addition of new chapters and major updates across multiple areas, as well as increasing the number of ways to access and use the information assembled*For this year\u27s edition, the Statistics Committee, which produces the document for the AHA, updated all of the current chapters with the most recent nationally representative data and inclusion of relevant articles from the literature over the past year*This year\u27s edition also implements a new chapter organization to reflect the spectrum of cardiovascular health behaviors and health factors and risks, as well as subsequent complicating conditions, disease states, and outcomes*Also, the 2013 Statistical Update contains new data on the monitoring and benefits of cardiovascular health in the population, with additional new focus on evidence-based approaches to changing behaviors, implementation strategies, and implications of the AHA\u27s 2020 Impact Goals*Below are a few highlights from this year\u27s Update . © 2013 American Heart Association, Inc
Executive summary: heart disease and stroke statistics--2014 update: a report from the American Heart Association.
Each year, the American Heart Association (AHA), in conjunction with the Centers for Disease Control and Prevention, the National Institutes of Health, and other government agencies, brings together the most up-to-date statistics on heart disease, stroke, other vascular diseases, and their risk factors and presents them in its Heart Disease and Stroke Statistical Update. The Statistical Update is a critical resource for researchers, clinicians, healthcare policy makers, media professionals, the lay public, and many others who seek the best available national data on heart disease, stroke, and other cardiovascular disease-related morbidity and mortality and the risks, quality of care, use of medical procedures and operations, and costs associated with the management of these diseases in a single document. Indeed, since 1999, the Statistical Update has been cited >10 500 times in the literature, based on citations of all annual versions. In 2012 alone, the various Statistical Updates were cited ≈3500 times (data from Google Scholar). In recent years, the Statistical Update has undergone some major changes with the addition of new chapters and major updates across multiple areas, as well as increasing the number of ways to access and use the information assembled. For this year's edition, the Statistics Committee, which produces the document for the AHA, updated all of the current chapters with the most recent nationally representative data and inclusion of relevant articles from the literature over the past year. This year's edition includes a new chapter on peripheral artery disease, as well as new data on the monitoring and benefits of cardiovascular health in the population, with additional new focus on evidence-based approaches to changing behaviors, implementation strategies, and implications of the AHA's 2020 Impact Goals. Below are a few highlights from this year's Update. © 2013 American Heart Association, Inc
Heart Disease and Stroke Statistics-2016 Update: A Report From the American Heart Association.
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Illustrating the effect of viscoelastic additives on cavitation and turbulence with X-ray imaging
The effect of viscoelastic additives on the topology and dynamics of the two-phase flow arising within an axisymmetric orifice with a flow path constriction along its main axis has been investigated employing high-flux synchrotron radiation. X-ray Phase Contrast Imaging (XPCI) has been conducted to visualise the cavitating flow of different types of diesel fuel within the orifice. An additised blend containing Quaternary Ammonium Salt (QAS) additives with a concentration of 500 ppm has been comparatively examined against a pure (base) diesel compound. A high-flux, 12 keV X-ray beam has been utilised to obtain time resolved radiographs depicting the vapour extent within the orifice from two views (side and top) with reference to its main axis. Different test cases have been examined for both fuel types and for a range of flow conditions characterised by Reynolds number of 35500 and cavitation numbers (CN) lying in the range 3.0–7.7. It has been established that the behaviour of viscoelastic micelles in the regions of shear flow is not consistent depending on the cavitation regimes encountered. Namely, viscoelastic effects enhance vortical (string) cavitation, whereas hinder cloud cavitation. Furthermore, the use of additised fuel has been demonstrated to suppress the level of turbulence within the orifice
Exploring the current status of forest stock in the areas bordering Dinder Biosphere Reserve, Sudan
Dinder Biosphere Reserve (DBR) is the one of first protected areas in Sudan. It hosts diversified populations of plants and animals species ranging from annual plants and grasses to mature and over mature trees, as well as, birds and herbivores to large carnivores. However, with all this diversity, information about the current status of forest resources around the reserve is lacking. Therefore, this study is exploring the current status of forest stock in the areas surrounding the Dinder Biosphere Reserve, in order to bridge the current information gap for attaining sustainable management of natural resources in the area. Six forest reserves were selected for data collection due to their nearest position and important to the DBR. For data collection, a point sampling method was applied with a 10 % as sampling intensity across the six sites. In each sample plot (1ha) after the determination of the tree species, the measured variables include number of trees per hectare, diameter at breast height, total tree height, crown diameter and crown height. Paired samples T test in Minitab (Version 17) were used to compares between the various growth parameters. Our results revealed that growth parameters differed significantly between riverine forest reserves with no significant differences among natural forests. Fazara natural forest reserve revealed the maximum value of tree density, however, Badous riverine forest reserve showed the highest mean value for tree density throughout the study area. Besides that, the study findings also distinguished Acacia seyal var fistula, Adansonia digitata and Tamarindus indica as rare tree species in all six-forest reserves. The study recommended that urgent protection measures are needed in the study area in order to conserve these rare tree species before they disappear from their natural ranges
Self-association of Rifamycin B: Possible Effects on Molecular Recognition
The macrocyclic antibiotic rifamycin B was found to be highly surface-active and to aggregate in aqueous solution. The aggregational behavior was studied using small-angle neutron scattering (SANS). Aqueous solutions of rifamycin B showed pronounced scattering at both small-length scales (Q ≥ 0.1 Å-1) and at large-length scales (Q ≤ 0.1 Å-1). The larger association colloids appear to be rather open low-density aggregates. The addition of 10% 2-propanol greatly reduces the number and size of the aggregates. Somewhat higher amounts of alcohol appear to completely suppress or eliminate aggregation. The suppression of aggregation coincides with the appearance and enhancement of enantioselective association between rifamycin B and a variety of chiral amino alcohols. It appears that the self-aggregation of rifamycin B may be a factor that controls its ability to differentiate between enantiomers in aqueous and hydro-organic solutions. © 1999 American Chemical Society
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