1,704 research outputs found

    BFB \wedge F Term by Spontaneous Symmetry Breaking in a generalized Abelian Higgs Model

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    We show that the topological BFB \wedge F term in 3+13+1 dimensions can be generated via spontaneous symmetry breaking in a generalized Abelian Higgs model. Further, we also show that even in DD dimensions (D3) ( D \geq 3 ) , a BFB \wedge F term gives rise to the topological massive excitations of the Abelian gauge field and that such a BFB \wedge F term can also be generated via Higgs mechanism.Comment: 7 pages, RevTeX, IP/BBSR/94-2

    Diethyl­enetriaminium hexa­fluorido­titanate(IV) fluoride

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    The title compound, (C6H21N4)[TiF6]F, was synthesized by the reaction of TiO2, tris­(2-amino­ethyl)amine, HF and ethanol at 463 K in a microwave oven. The crystal structure consists of two crystallographically independent [TiF6]2− anions, two fluoride anions and two triply-protonated tris­(2-amino­ethyl)­amine cations. The Ti atoms are coordinated by six F atoms within slightly distorted octa­hedra. The anions and cations are connected by inter­molecular N—H⋯F hydrogen bonds

    The Hot Horizontal-Branch Stars in NGC288 - Effects of Diffusion and Stratification on Their Atmospheric Parameters*

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    Context. NGC288 is a globular cluster with a well developed blue horizontal branch covering the so-called u-jump which indicates the onset of diffusion. It is therefore well suited to study the effects of diffusion in blue horizontal branch (HB) stars. Aims. We compare observed abundances to predictions from stellar evolution models calculated with diffusion and from stratified atmospheric models. We verify the effect of using stratified model spectra to derive atmospheric parameters. In addition we investigate the nature of the overluminous blue HB stars around the u-jump. Methods. We define a new photometric index sz from uvby measurements that is gravity sensitive between 8 000K and 12 000 K. Using medium-resolution spectra and Stroemgren photometry we determine atmospheric parameters (Teff, logg) and abundances for the blue HB stars. We use both homogeneous and stratified model spectra for our spectroscopic analyses. Results. The atmospheric parameters and masses of the hot HB stars in NGC288 show a behaviour seen also in other clusters for temperatures between 9 000K and 14 000 K. Outside this temperature range, however, they follow rather the results found for such stars in (omega)Cen. The abundances derived from our observations are for most elements (except He and P) within the abundance range expected from evolutionary models that include the effects of atomic diffusion and assume a surface mixed mass of 10(exp 7) M. The abundances predicted by stratified model atmospheres are generally significantly more extreme than observed, except for Mg. The use of stratified model spectra to determine effective temperatures, surface gravities and masses moves the hotter stars to a closer agreement with canonical evolutionary predictions. Conclusions. Our results show definite promise towards solving the long-standing issue of surface gravity and mass discrepancies for hot HB stars, but there is still much work needed to arrive at a self-consistent solution

    Topologically Massive Non-Abelian Gauge Theories: Constraints and Deformations

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    We study the relationship between three non-Abelian topologically massive gauge theories, viz. the naive non-Abelian generalization of the Abelian model, Freedman-Townsend model and the dynamical 2-form theory, in the canonical framework. Hamiltonian formulation of the naive non-Abelian theory is presented first. The other two non-Abelian models are obtained by deforming the constraints of this model. We study the role of the auxiliary vector field in the dynamical 2-form theory in the canonical framework and show that the dynamical 2-form theory cannot be considered as the embedded version of naive non-Abelian model. The reducibility aspect and gauge algebra of the latter models are also discussed.Comment: ReVTeX, 17 pp; one reference added, version published in Phys. Rev.

    Optimization of care for patients with hereditary angioedema living in rural areas

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    BACKGROUND: People living in rural areas of the United States experience greater health inequality than individuals residing in urban or suburban locations and encounter several barriers to obtaining optimal health care. Health disparities are compounded for patients with rare diseases such as hereditary angioedema (HAE), an autosomal dominant genetic disorder characterized by recurrent, severe abdominal pain and life-threatening oropharyngeal or laryngeal swelling. OBJECTIVE: To explore the challenges of managing patients with HAE in rural areas and suggest possible improvements for optimizing care. DATA SOURCES: PubMed was searched for articles on patient care management, treatment challenges, rural health, and HAE. STUDY SELECTIONS: Relevant articles were selected and reviewed. RESULTS: Challenges in managing HAE in the rural setting were identified, including obtaining a diagnosis of HAE, easy access to a physician with expertise in HAE, continuity of care, availability of telemedicine services, access to approved HAE therapies, patient education, and economic barriers to treatment. Ways to improve HAE patient care in rural areas include health care provider recognition of the patient with undiagnosed HAE, development of individualized management plans, expansion of telemedicine, effective care at the local level, appropriate access to HAE medication, and increased awareness of patient support and advocacy groups. CONCLUSION: For patients with HAE living in rural areas, optimal care is complicated by health disparities. Given the scarcity with which these topics have been covered in the literature to date, it is intended that this article will serve as the impetus for a range of further initiatives focused on improving access to care

    Gauge Vector Masses from Flat Connections?

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    We suggest that four dimensional massive gauge vectors could be described by coupling ordinary Yang-Mills theory to a topological gauge theory. For this the coupling should excite a nontrivial degree of freedom from the topological theory, corresponding to the longitudinal polarization of a massive gauge vector. If the coupling can be selected so that further degrees of freedom are not excited, one may entirely avoid particles such as the Higgs. Here we discuss a simple example of this idea, obtained by coupling standard Yang-Mills theory to the topological gauge theory of flat connections. We propose that our example might describe a renormalizable theory of massive gauge vectors with no additional physical degrees of freedom.Comment: 13 pages Latex. Some minor typos have been fixe

    First principles simulations of liquid Fe-S under Earth's core conditions

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    First principles electronic structure calculations, based upon density functional theory within the generalized gradient approximation and ultra-soft Vanderbilt pseudopotentials, have been used to simulate a liquid alloy of iron and sulfur at Earth's core conditions. We have used a sulfur concentration of 12\approx 12 % wt, in line with the maximum recent estimates of the sulfur abundance in the Earth's outer core. The analysis of the structural, dynamical and electronic structure properties has been used to report on the effect of the sulfur impurities on the behavior of the liquid. Although pure sulfur is known to form chains in the liquid phase, we have not found any tendency towards polymerization in our liquid simulation. Rather, a net S-S repulsion is evident, and we propose an explanation for this effect in terms of the electronic structure. The inspection of the dynamical properties of the system suggests that the sulfur impurities have a negligible effect on the viscosity of Earth's liquid core.Comment: 24 pages (including 8 figures

    Еволюція рослинного світу в природному і культигенному середовищі

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    У ході засідань Міжнародної наукової конференції “Еволюція рослинного світу в природному і культигенному середовищі”, присвяченої 200-річчю від Дня народження Чарльза Дарвіна, обговорено актуальні питання еволюційної теорії, ботаніки, фізіології рослин, інтродукції, генетики й селекції, екології, збереження і примноження глобального та локального біорізноманіття, лісових культур і фітомеліорації та інших біологічних наук.В ходе заседаний Международной научной конференции “Эволюция растительного мира в естественной и культигенной среде”, посвященной 200-летию со дня рождения Чарльза Дарвина, обсуждены актуальные вопросы эволюционной теории, ботаники, физиологии растений, интродукции, генетики и селекции, экологии, сохранения и приумножения глобального и локального биоразнообразия, лесных культур и фитомелиорации и других биологических наук.During meetings of the International scientific conference “Evolution of the natural and cultivated plants” to devoted a 200-year from the day of birth of Charles Darwin topical problems of the evolutional theory are discussed, including botany, physiology of plants, introduction of plants, genetics and breeding of plants, ecology, preventing the loss of global and loca biodiversity, arboriculture, forest-growing and other biological sciences

    Ground water and climate change

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    As the world’s largest distributed store of fresh water, ground water plays a central part in sustaining ecosystems and enabling human adaptation to climate variability and change. The strategic importance of ground water for global water and food security will probably intensify under climate change as more frequent and intense climate extremes (droughts and floods) increase variability in precipitation, soil moisture and surface water. Here we critically review recent research assessing the impacts of climate on ground water through natural and human-induced processes as well as through groundwater-driven feedbacks on the climate system. Furthermore, we examine the possible opportunities and challenges of using and sustaining groundwater resources in climate adaptation strategies, and highlight the lack of groundwater observations, which, at present, limits our understanding of the dynamic relationship between ground water and climate

    Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

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    This paper presents measurements of the W+μ+νW^+ \rightarrow \mu^+\nu and WμνW^- \rightarrow \mu^-\nu cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
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