15,219 research outputs found

    Measuring Neutrino Oscillations with Nuclear Reactors

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    Since the first direct observations of antineutrino events by Reines and Cowan in the 1950's [1], nuclear reactors have been an important tool in the study of neutrino properties. More recently, the study of neutrino oscillations has been a very active area of research. The pioneering observation of oscillations by the KamLAND experiment has provided crucial information on the neutrino mixing matrix. New experiments to study the remaining unknown mixing angle are currently under development. These recent studies and potential future developments will be discussed

    Instabilities and propagation of neutrino magnetohydrodynamic waves in arbitrary direction

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    In a previous work [16], a new model was introduced, taking into account the role of the Fermi weak force due to neutrinos coupled to magnetohydrodynamic plasmas. The resulting neutrino-magnetohydrodynamics was investigated in a particular geometry associated with the magnetosonic wave, where the ambient magnetic field and the wavevector are perpendicular. The corresponding fast, short wavelength neutrino beam instability was then obtained in the context of supernova parameters. The present communication generalizes these results, allowing for arbitrary direction of wave propagation, including fast and slow magnetohydrodynamic waves and the intermediate cases of oblique angles. The numerical estimates of the neutrino-plasma instabilities are derived in extreme astrophysical environments where dense neutrino beams exist

    A Comparison of the Ovulation Method With the CUE Ovulation Predictor in Determining the Fertile Period

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    The purpose of this study was to compare the CUE Ovulation Predictor with the ovulation method in determining the fertile period. Eleven regularly ovulating women measured their salivary and vaginal electrical resistance (ER) with the CUE, observed their cervical-vaginal mucus, and measured their urine for a luteinizing hormone (LH) surge on a daily basis. Data from 21 menstrual cycles showed no statistical difference (T= 0.33, p= 0.63) between the CUE fertile period, which ranged from 5 to 10 days (mean = 6.7 days, SD = 1.6), and the fertile period of the ovulation method, which ranged from 4 to 9 days (mean = 6.5 days, SD = 2.0). The CUE has potential as an adjunctive device in the learning and use of natural family planning methods

    Systematic reduction of sign errors in many-body calculations of atoms and molecules

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    The self-healing diffusion Monte Carlo algorithm (SHDMC) [Phys. Rev. B {\bf 79}, 195117 (2009), {\it ibid.} {\bf 80}, 125110 (2009)] is shown to be an accurate and robust method for calculating the ground state of atoms and molecules. By direct comparison with accurate configuration interaction results for the oxygen atom we show that SHDMC converges systematically towards the ground-state wave function. We present results for the challenging N2_2 molecule, where the binding energies obtained via both energy minimization and SHDMC are near chemical accuracy (1 kcal/mol). Moreover, we demonstrate that SHDMC is robust enough to find the nodal surface for systems at least as large as C20_{20} starting from random coefficients. SHDMC is a linear-scaling method, in the degrees of freedom of the nodes, that systematically reduces the fermion sign problem.Comment: Final version accepted in Physical Review Letters. The review history (referees' comments and our replies) is included in the source

    Prediction of breeding values when variances are not known

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    Critical Success Factors Affecting E-Procurement Adoption in Public Sector Organizations in Sri Lanka

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    E-procurement is one of the Information Communication Technology (ICT) applications utilized in both public and private sector organizations. Many countries all over the world including Canada, Korea and Philippine benefited through the government procurement using electronic means as it enables the government to offer more convenient and widespread accessible government services in an efficient, cost-effective and participatory manner. The main objectives of the study are (a) to access the level of e-procurement usage in the public-sector in Sri Lanka; (b) to identify the significant factors affecting the public-sector e-procurement adoption in Sri Lanka; and (c) to identify the barriers in adopting e-procurement in those organizations. The population of the study comprises of the national level public sector entities such as; Ministries, Departments, Statutory Boards and Public Companies.  A sample of 114 officers who involved in the procurement function was selected as key informants based on stratified random sampling method. 74 officers were responded for the study. Both qualitative and quantitative methods were utilized in this study. Quantitative data were collected through a structured questionnaire to identify the determinants of successful e-procurement adoption and the level of e-procurement usage. The qualitative data were collected through 10 interviews to identify barriers in e-procurement adoption. The study found that Relative Advantage, Compatibility, Complexity, Top Management Support, Employee Knowledge and skills and Supplier Readiness are statistically significant (at p<0.01) determinants of e-procurement adoption.  These variables altogether explain 66.2% of variance in e-procurement adoption in the public-sector organizations in Sri Lanka. Among them, Top Management Support and Employee Knowledge are the major determinants of the successful e-procurement adoption. Weak procurement guidelines, Weak Legal framework and ICT infrastructure, and Lack of IT knowledge and experience of employees are the present barriers to e-procurement adoption in public sector organizations in Sri Lanka. Finally, policy recommendations for the e-procurement adoption are proposed.KeywordsCritical success factors; E-procurement adoption; National level public sector organization
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