7,411 research outputs found

    Non-integrality of some Steinberg modules

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    We prove that the Steinberg module of the special linear group of a quadratic imaginary number ring which is not Euclidean is not generated by integral apartments. Assuming the generalized Riemann hypothesis, this shows that the Steinberg module of a number ring is generated by integral apartments if and only if the ring is Euclidean. We also construct new cohomology classes in the top dimensional cohomology group of the special linear group of some quadratic imaginary number rings.Comment: 17 pages. To appear in Journal of Topolog

    One-pot near-ambient temperature syntheses of aryl(difluoroenol) derivatives from trifluoroethanol

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    Difluoroalkenylzinc reagents prepared from 1-(2’-methoxy-ethoxymethoxy)-2,2,2-trifluoroethane and 1-(N,N-diethylcarbamoyloxy)-2,2,2-trifluoroethane at ice bath temperatures, underwent Negishi coupling with a range of aryl halides in a convenient one pot procedure. While significant differences between the enol acetal and carbamate reagents were revealed, the Negishi protocol compared very favourably with alternative coupling procedures in terms of overall yields from trifluoroethanol

    Chandra localization of XTE J1906+090 and discovery of its optical and infrared counterparts

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    We present the Chandra identification and localization of the transient X-ray source XTE J1906+090 and the discovery of its optical and infrared counterparts. Our analysis of archival Chandra ACIS-I observations of the field found the source approximately 8 away from the position determined earlier with the RXTE PCA. We have confirmed the source identification with timing analysis of the X-ray data, which detected the source spin period of 89.6 s. The best Chandra position for the source is R.A. = 19h04m47491, decl. = +09024140. Subsequently, we performed optical observations of the field around the new location and discovered a coincident optical source with R-band magnitude of 18.7. A search in the Two Micron All Sky Survey catalog revealed an infrared point source with J = 15.2, H = 14.2, and K = 13.5, whose location is also coincident with our Chandra and optical positions. Our results add fresh evidence for a Be/X-ray transient nature for XTE J1906+090

    Sociodemographic Correlates of Sexlessness Among American Adults and Associations with Self-Reported Happiness Levels: Evidence from the U.S. General Social Survey

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    Although sexual activity is commonly believed to be a key component of emotional well-being, little is known about the factors associated with the absence of sexual activity or its associations with self-reported happiness. Using the U.S. General Social Survey–National Death Index 2008 dataset, a series of nationally representative surveys (1988–2002), this study analyzed the sociodemographic and lifestyle factors associated with past-year sexlessness and self-reported happiness among American adults (n = 17,744). After adjustment for marital status, there were no significant time trends evident in the proportion of American adults reporting past-year sexlessness. Among participants (age = 18–89 years), 15.2% of males and 26.7% of females reported past-year sexlessness while 8.7% of males and 17.5% of females reported no sex for 5 years or more. For both genders, past-year sexlessness was most strongly associated with older age and being currently non-married in the multivariable models. Among males, the multivariable analysis also showed that sexlessness was associated with providing less than 20% of the house-hold income (OR 2.27). In female participants, sexlessness was associated with very low income, poor health, lower financial satisfaction, absence of children, and having conservative sexual attitudes (OR 1.46–3.60). For both genders, Black race was associated with a much lower likelihood of sexlessness among currently non-married adults. The purported detrimental impact of sexlessness on self-reported happiness levels was not evident in this large, nationally representative study after adjusting for sociodemographic factors. Sexless Americans reported very similar happiness levels as their sexually active counterparts

    Success factors between suppliers and customers in service outsourcing activities

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    This study examines the relationship between outsourcing motives, supplier-customer relationship and perceived value in non-core service outsourcing. That is, key factors responsible for supplier-customer relationship which provide customer value in service outsourcing is still unclear. A total of 1,757 companies were randomly selected for the survey. 234 valid questionnaires were returned (13.4% response rate). The structural equation method was used to obtain the best fit model. The most significant contribution of this study is that, ‘relationship interaction’ has a greater impact on customer perceived value than ‘relationship quality’ in service outsourcing. That is, customer-supplier ‘relationship interaction’ that enhances communication, cooperation, coordination, conflict resolution, and integration activities rather than ‘relationship quality’ such as loyalty and trust, would exert the greatest effect on perceived customer value

    On the generalized Bykovskii presentation of Steinberg modules

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    We study presentations of the virtual dualizing modules of special linear groups of number rings, the Steinberg modules. Bykovskii gave a presentation for the Steinberg modules of the integers, and our main result is a generalization of this presentation to the Gaussian integers and the Eisenstein integers. We also show that this generalization does not give a presentation for the Steinberg modules of several Euclidean number rings.Comment: Minor revisions based on referee's comments. Accepted for publication at IMR
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