1,607 research outputs found

    Decays of =1\ell=1 Baryons --- Quark Model versus Large-NcN_c

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    We study nonleptonic decays of the orbitally excited, \su6 \rep{70}-plet baryons in order to test the hypothesis that the successes of the nonrelativistic quark model have a natural explanation in the large-NcN_c limit of QCD. By working in a Hartree approximation, we isolate a specific set of operators that contribute to the observed s- and d-wave decays in leading order in 1/Nc1/N_c. We fit our results to the current experimental decay data, and make predictions for a number of allowed but unobserved modes. Our tentative conclusion is that there is more to the nonrelativistic quark model of baryons than large-NcN_c.Comment: LaTeX 49pp. (38 pp. landscape), PicTex, PrePicTex, PostPicTex required for 3 figures, Harvard Preprint HUTP-94/A008. (Two additional operators are included, but conclusions are unchanged.

    Green suppler selection by an integrated method with stochastic acceptability analysis and MULTIMOORA

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    In the process of supplier selection for green supply chain management, uncertain information may appear in alternatives’ performances or experts’ preferences. The stochastic multicriteria acceptability analysis (SMAA) is a beneficial technique to tackling the uncertain information in such a problem and the MULTIMOORA is a robust technique to aggregate alternatives’ utilities. This study dedicates to proposing an SMAA-MULTIMOORA method by considering the advantages of both methods. The integrated method can accept uncertain information as inputs. The steps of the SMAA-MULTIMOORA are illustrated. A case study about the selection of green suppliers is given to show the validity and robustness of the SMAA-MULTIMOORA method

    Painful sex (dyspareunia) in women: prevalence and associated factors in a British population probability survey.

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    ObjectiveTo estimate the prevalence of painful sex among women in Britain, and to explore associated sexual, relationship and health factors that should be considered in assessment.DesignMulti-stage, clustered and stratified population probability sample survey, using computer-assisted self-interview. Sample frame was the British Postcode Address File.SettingParticipants interviewed at home between 2010 and 2012.SampleA total of 15 162 adults aged 16-74 years (8869 women). Data reported from 6669 sexually active women.MethodsAge-adjusted logistic regressions to examine associations between painful sex and indicators of sexual, relational, mental and physical health.Main outcome measurePhysical pain as a result of sex for ≥3 months in the past year, plus measures of symptom severity.ResultsPainful sex was reported by 7.5% (95% CI 6.7-8.3) of sexually active women, of whom one-quarter experienced symptoms very often or always, for ≥6 months, and causing distress. Reporting painful sex was strongly associated with other sexual function problems, notably vaginal dryness (age adjusted odds ratio 7.9; 6.17-10.12), anxiety about sex (6.34; 4.76-8.46) and lacking enjoyment in sex (6.12; 4.81-7.79). It was associated with sexual relationship factors [such as not sharing same level of interest in sex (2.56; 1.97-3.33)], as well as with adverse experiences such as non-volitional sex (2.17; 1.68-2.80). Associations were also found with measures of psychological and physical health, including depressive symptoms (1.68; 1.28-2.21).ConclusionPainful sex is reported by a sizeable minority of women in Britain. Health professionals should be supported to undertake holistic assessment and treatment which takes account of the sexual, relationship and health context of symptoms.Tweetable abstractPainful sex-reported by 7.5% of women in Britain-is linked to poorer sexual, physical, relational and mental health

    The Red Sea under the Caliphal Dynasties, c. 639–1171

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    Students of world history will be familiar with the Red Sea as a strategic communications corridor linking the Mediterranean to the Indian Ocean. This paper examines the Red Sea region between the seventh and twelfth centuries, when it was ruled by a succession of Islamic caliphal dynasties, namely, the Umayyads, ʿAbbāsids, and Fāṭimids. It first sets out a sketch of the political history of the Red Sea and its constituent hinterland polities, including particularly Egypt, Sudan, al‐Ḥijāz, and Yemen, drawing attention to episodes and processes in which the Red Sea was significant. A section on Africa and Arabia explores the Red Sea as a zone of economic and social interaction; another section deals with the historic shift of Indian Ocean trade from the ʿAbbāsid Persian Gulf to the Fāṭimid Red Sea. Finally, the impact of the Red Sea on its constituent hinterland polities and the wider sweep of Islamic history is considered

    Leptogenesis in a Realistic Supersymmetric Model of Inflation with a Low Reheat Temperature

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    We discuss leptogenesis in a realistic supersymmetric model of inflation with a low reheat temperature 1-10 GeV. The lepton asymmetry is generated by a decaying right handed sneutrino, which is produced after inflation during preheating. The inflationary model is based on a simple variant of the Next-to-Minimal Supersymmetric Standard model (NMSSM) which solves the \mu problem, called \phiNMSSM, where the additional singlet \phi plays the role of the inflaton in hybrid (or inverted hybrid) type models. The model is invariant under an approximate Peccei-Quinn symmetry which also solves the strong CP problem, and leads to an invisible axion with interesting cosmological consequences. We show how the baryon number of the universe and the nature of cold dark matter are determined by the same parameters controlling the strong CP problem, the \mu problem and the neutrino masses and mixing angles.Comment: 17 page, latex, 1 eps fi

    The Nile: its role in the fortunes and misfortunes of the Fatimid dynasty during its rule of Egypt (969-1171)

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    The epoch spanning the years 935-1094 constitutes - on the whole - the longest and driest period on record in the history of the Nile. A stretch of relatively normal discharge followed this phase, only for dryness to return. The reasons of this dry-wet-dry phenomenon have been recently appraised in the context of global climatic changes – the so-called “Medieval Warm Period” - that affected most of the known world between the 11th and the 13th centuries. It was in this period of Egyptian history that the Shi‘i Isma‘ili Fatimids replaced the Sunni Ikhshidids as rulers in 358/969 and, with alternating fortunes, continued to reign until 567/1171. In this paper, I examine how, faced with the convergence of extraordinary geo-climatic factors, the Fatimids managed (and mismanaged) the Nile and its valley. I contend that the imperial aspirations of the Fatimids in Cairo and beyond were in many ways subject to the typical unpredictability of the natural cycles of the river, hence the Fatimids’ success and failure in managing the varied economic, political and trading activities that took place along the Egyptian section of the Nile valley. A case in point highlighted here will be the Fatimids’ privileging of flax cultivation over wheat

    Nonspecific synaptic plasticity improves the recognition of sparse patterns degraded by local noise

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    Safaryan, K. et al. Nonspecific synaptic plasticity improves the recognition of sparse patterns degraded by local noise. Sci. Rep. 7, 46550; doi: 10.1038/srep46550 (2017). This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ © The Author(s) 2017.Many forms of synaptic plasticity require the local production of volatile or rapidly diffusing substances such as nitric oxide. The nonspecific plasticity these neuromodulators may induce at neighboring non-active synapses is thought to be detrimental for the specificity of memory storage. We show here that memory retrieval may benefit from this non-specific plasticity when the applied sparse binary input patterns are degraded by local noise. Simulations of a biophysically realistic model of a cerebellar Purkinje cell in a pattern recognition task show that, in the absence of noise, leakage of plasticity to adjacent synapses degrades the recognition of sparse static patterns. However, above a local noise level of 20 %, the model with nonspecific plasticity outperforms the standard, specific model. The gain in performance is greatest when the spatial distribution of noise in the input matches the range of diffusion-induced plasticity. Hence non-specific plasticity may offer a benefit in noisy environments or when the pressure to generalize is strong.Peer reviewe

    Human embryonic stem cells from aneuploid blastocysts identified by pre-implantation genetic screening

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    Human embryonic stem cells are derived from the inner cell mass of pre-implantation embryos. The cells have unlimited proliferation potential and capacity to differentiate into the cells of the three germ layers. Human embryonic stem cells are used to study human embryogenesis and disease modeling and may in the future serve as cells for cell therapy and drug screening. Human embryonic stem cells are usually isolated from surplus normal frozen embryos and were suggested to be isolated from diseased embryos detected by pre-implantation genetic diagnosis. Here we report the isolation of 12 human embryonic stem cell lines and their thorough characterization. The lines were derived from embryos detected to have aneuploidy by pre-implantation genetic screening. Karyotype analysis of these cell lines showed that they are euploid, having 46 chromosomes. Our interpretation is that the euploid cells originated from mosaic embryos, and in vitro selection favored the euploid cells. The undifferentiated cells exhibited long-term proliferation and expressed markers typical for embryonic stem cells such as OCT4, NANOG, and TRA-1-60. The cells manifested pluripotent differentiation both in vivo and in vitro. To further characterize the different lines, we have analyzed their ethnic origin and the family relatedness among them. The above results led us to conclude that the aneuploid mosaic embryos that are destined to be discarded can serve as source for normal euploid human embryonic stem cell lines. These lines represent various ethnic groups; more lines are needed to represent all populations
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