4,720 research outputs found

    Rare-earth impurities in Co2_2MnSi: an opportunity to improve Half-Metallicity at finite temperatures

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    We analyse the effects of doping Holmium impurities into the full-Heusler ferromagnetic alloy Co2_2MnSi. Experimental results, as well as theoretical calculations within Density Functional Theory in the "Local Density Approximation plus Hubbard U" framework show that the holmium moment is aligned antiparallely to that of the transition metal atoms. According to the electronic structure calculations, substituting Ho on Co sites introduces a finite density of states in the minority spin gap, while substitution on the Mn sites preserves the half-metallic character.Comment: 22 pages, 8 figures. published in PR

    The Higgs portal and an unified model for dark energy and dark matter

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    We examine a scenario where the Higgs boson is coupled to an additional singlet scalar field which we identify with a quintessence field. We show that this results in an unified picture of dark matter and dark energy, where dark energy is the zero-mode classical field rolling the usual quintessence potential and the dark matter candidate is the quantum excitation (particle) of the field, which is produced in the universe due to its coupling to the Higgs boson.Comment: 5 pages, no figures. New references and acknowledgment adde

    The Influence of the Agricultural Cluster on the Fayette County Economy [2017]

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    Executive Summary: Historically, employment associated with agriculture in Fayette County has been limited to production agriculture. Recently, the Ag Cluster has been extended to include agricultural inputs and food processing and manufacturing. However, there are hundreds of establishments in the county that are service-based (finance, veterinary, recreation), transportation, communications, as well as wholesale and retail businesses that are 100% dedicated to agriculture. These businesses have never been included in an economic impact study exploring the impact of agriculture in Fayette County. Ignoring these businesses underestimates the value of the agricultural sector. This is particularly important in Fayette County because of its competitive advantage in the equine industry. In 2012, CEDIK (Community and Economic Development Initiative of Kentucky) at the University of Kentucky presented findings that highlighted the value of this expanded definition of the Ag Cluster in Fayette County. CEDIK conducted an extensive search of agricultural enterprises within the county and estimated the total number of jobs, output, and labor income associated with this cluster. The purpose of this study is to provide an update of these numbers and to update the Fayette County Ag Cluster Business database. When the Ag Cluster is defined to include business services, retail, and wholesale trade solely dedicated to agriculture, in addition to the traditional way agriculture has been measured, it is estimated that a total of 14,091 jobs are attributed to this cluster. In addition, there are approximately 1,724 jobs directly and indirectly associated with the hospitality sector in Lexington. Given total employment in the county (approximately 189,946) these results suggest that roughly 1 out of every 12 jobs is directly or indirectly associated with the Ag Cluster. Employment in the Ag Cluster contributes approximately 8.5milliontothelocaltaxbasethroughthe2.25Inaddition,theAgClustergeneratesapproximately8.5 million to the local tax base through the 2.25% occupational tax rate. In addition, the Ag Cluster generates approximately 2.3 billion in output annually and $1.3 billion dollars in additional income, profits, and dividends

    A giant ring-like structure at 0.78<z<0.86 displayed by GRBs

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    According to the cosmological principle, Universal large-scale structure is homogeneous and isotropic. The observable Universe, however, shows complex structures even on very large scales. The recent discoveries of structures significantly exceeding the transition scale of 370 Mpc pose a challenge to the cosmological principle. We report here the discovery of the largest regular formation in the observable Universe; a ring with a diameter of 1720 Mpc, displayed by 9 gamma ray bursts (GRBs), exceeding by a factor of five the transition scale to the homogeneous and isotropic distribution. The ring has a major diameter of 43o43^o and a minor diameter of 30o30^o at a distance of 2770 Mpc in the 0.78<z<0.86 redshift range, with a probability of 2×1062\times 10^{-6} of being the result of a random fluctuation in the GRB count rate. Evidence suggests that this feature is the projection of a shell onto the plane of the sky. Voids and string-like formations are common outcomes of large-scale structure. However, these structures have maximum sizes of 150 Mpc, which are an order of magnitude smaller than the observed GRB ring diameter. Evidence in support of the shell interpretation requires that temporal information of the transient GRBs be included in the analysis. This ring-shaped feature is large enough to contradict the cosmological principle. The physical mechanism responsible for causing it is unknown.Comment: Accepted for publication in MNRAS, 13 pages, 8 figures and 4 table

    Frame Theory for Signal Processing in Psychoacoustics

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    This review chapter aims to strengthen the link between frame theory and signal processing tasks in psychoacoustics. On the one side, the basic concepts of frame theory are presented and some proofs are provided to explain those concepts in some detail. The goal is to reveal to hearing scientists how this mathematical theory could be relevant for their research. In particular, we focus on frame theory in a filter bank approach, which is probably the most relevant view-point for audio signal processing. On the other side, basic psychoacoustic concepts are presented to stimulate mathematicians to apply their knowledge in this field

    Dynamics of Phase Behavior of a Polymer Blend Under Shear Flow

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    We study the dynamics of the phase behavior of a polymer blend in the presence of shear flow. By adopting a two fluid picture and using a generalization of the concept of material derivative, we construct kinetic equations that describe the phase behavior of polymer blends in the presence of external flow. A phenomenological form for the shear modulus for the blend is proposed. The study indicates that a nonlinear dependence of the shear modulus of the blend on the volume fraction of one of the species is crucial for a shift in the stability line to be induced by shear flow.Comment: 16 pages, late

    The common truncation variant in pancreatic lipase related protein 2 (PNLIPRP2) is expressed poorly and does not alter risk for chronic pancreatitis

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    A nonsense variant (p.W358X) of human pancreatic lipase related protein 2 (PNLIPRP2) is present in different ethnic populations with a high allele frequency. In cell culture experiments, the truncated protein mainly accumulates inside the cells and causes endoplasmic reticulum stress. Here, we tested the hypothesis that variant p.W358X might increase risk for chronic pancreatitis through acinar cell stress. We sequenced exon 11 of PNLIPRP2 in a cohort of 256 subjects with chronic pancreatitis (152 alcoholic and 104 non-alcoholic) and 200 controls of Hungarian origin. We observed no significant difference in the distribution of the truncation variant between patients and controls. We analyzed mRNA expression in human pancreatic cDNA samples and found the variant allele markedly reduced. We conclude that the p.W358X truncation variant of PNLIPRP2 is expressed poorly and has no significant effect on the risk of chronic pancreatitis
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