17,301 research outputs found

    Type IIA Orientifold Limit of M-Theory on Compact Joyce 8-Manifold of Spin(7)-Holonomy

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    We show that M-theory compactified on a compact Joyce 8-manifold of Spin(7)Spin(7)-holonomy, which yields an effective theory in D=3D = 3 with N\N = 1 supersymmetry, admits at some special points in it moduli space a description in terms of type IIA theory on an orientifold of compact Joyce 7-manifold of G2G_2-holonomy. We find the evidence in favour of this duality by computing the massless spectra on both M-thory side and type IIA side. For the latter, we compute the massless spectra by going to the orbifold limit of the Joyce 7-manifold.Comment: 26 pages, 2 eps figures, Latex file, two references and one footnote added, corrected some typo

    Peroxisome Proliferator-activated receptor alpha gene variation influences age of onset and progression of type 2 diabetes

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    Dysregulation of fatty acid metabolism is important in the pathogenesis of type 2 diabetes. Peroxisome proliferator-activated receptor (PPAR) is a master regulator of fatty acid catabolism, and PPAR activators delay the onset of type 2 diabetes. We examined association between three PPAR gene polymorphisms (an AC variant in intron 1, the L162V variant, and the intron 7 GC variant) and age at diagnosis of type 2 diabetes in 912 Caucasian type 2 diabetic subjects. Individually, PPAR gene variants did not influence age at diagnosis, but in combination, the rare alleles of both the intron 1 AC (P < 0.001) and intron 7 GC (P = 0.025) variants synergistically lowered age at diagnosis (interaction P < 0.001). Overall, the PPAR haplotype signficantly influenced age at diagnosis (P = 0.027), with the C-L-C and C-V-C haplotypes (intron 1-L162V-intron 7) accelerating onset of diabetes by 5.9 (P = 0.02) and 10 (P = 0.03) years, respectively, as compared with the common A-L-G haplotype, and was associated with an odds ratio for early-onset diabetes (age at diagnosis 45 years) of 3.75 (95% CI 1.65–8.56, P = 0.002). Intron 1 C-allele carriers also progressed more rapidly to insulin monotherapy (AA 9.4 ± 1.5 and AC + CC 5.3 ± 1.1 years, P = 0.002). These data indicate that PPAR gene variation influences the onset and progression of type 2 diabetes

    Measuring systemic risk

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    We present a simple model of systemic risk and show how each financial institution’s contribution to systemic risk can be measured and priced. An institution’s contribution, denoted systemic expected shortfall (SES), is its propensity to be undercapitalized when the system as a whole is undercapitalized, which increases in its leverage, volatility, correlation, and tail-dependence. Institutions internalize their externality if they are “taxed” based on their SES. Through several examples, we demonstrate empirically the ability of components of SES to predict emerging systemic risk during the nancial crisis of 2007-2009.Systemic risk ; Risk

    In search of the right literature search engine(s)

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    *Background*&#xd;&#xa;Collecting scientific publications related to a specific topic is crucial for different phases of research, health care and &#x2018;effective text mining&#x2019;. Available bio-literature search engines vary in their ability to scan different sections of articles, for the user-provided search terms and/or phrases. Since a thorough scientific analysis of all major bibliographic tools has not been done, their selection has often remained subjective. We have considered most of the existing bio-literature search engines (http://www.shodhaka.com/startbioinfo/LitSearch.html) and performed an extensive analysis of 18 literature search engines, over a period of about 3 years. Eight different topics were taken and about 50 searches were performed using the selected search engines. The relevance of retrieved citations was carefully assessed after every search, to estimate the citation retrieval efficiency. Different other features of the search tools were also compared using a semi-quantitative method.&#xd;&#xa;*Results*&#xd;&#xa;The study provides the first tangible comparative account of relative retrieval efficiency, input and output features, resource coverage and a few other utilities of the bio-literature search tools. The results show that using a single search tool can lead to loss of up to 75% relevant citations in some cases. Hence, use of multiple search tools is recommended. But, it would also not be practical to use all or too many search engines. The detailed observations made in the study can assist researchers and health professionals in making a more objective selection among the search engines. A corollary study revealed relative advantages and disadvantages of the full-text scanning tools.&#xd;&#xa;*Conclusion*&#xd;&#xa;While many studies have attempted to compare literature search engines, important questions remained unanswered till date. Following are some of those questions, along with answers provided by the current study:&#xd;&#xa;a)&#x9;Which tools should be used to get the maximum number of relevant citations with a reasonable effort? ANSWER: _Using PubMed, Scopus, Google Scholar and HighWire Press individually, and then compiling the hits into a union list is the best option. Citation-Compiler (http://www.shodhaka.com/compiler) can help to compile the results from each of the recommended tool._&#xd;&#xa;b)&#x9;What is the approximate percentage of relevant citations expected to be lost if only one search engine is used? ANSWER: _About 39% of the total relevant citations were lost in searches across 4 topics; 49% hits were lost while using PubMed or HighWire Press, while 37% and 20% loss was noticed while using Google Scholar and Scopus, respectively._ &#xd;&#xa;c)&#x9;Which full text search engines can be recommended in general? ANSWER: _HighWire Press and Google Scholar._&#xd;&#xa;d)&#x9;Among the mostly used search engines, which one can be recommended for best precision? ANSWER: _EBIMed._&#xd;&#xa;e)&#x9;Among the mostly used search engines, which one can be recommended for best recall? ANSWER: _Depending on the type of query used, best recall could be obtained by HighWire Press or Scopus.
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