227 research outputs found

    The luminosity constraint on solar neutrino fluxes

    Get PDF
    A specific linear combination of the total solar neutrino fluxes must equal the measured solar photon luminosity if nuclear fusion reactions among light elements are responsible for solar energy generation. This luminosity constraint, previously used in a limited form in testing the no neutrino oscillation hypothesis, is derived in a generality that includes all of the relevant solar neutrino fluxes and which is suitable for analyzing the results of many different solar neutrino experiments. With or without allowing for neutrino oscillations, the generalized luminosity constraint can be used in future analyses of solar neutrino data. Accurate numerical values for the linear coefficients are provided.Comment: related material at http://www.sns.ias.edu/~jn

    Synthesis, Molecular Structure, and 1H NMR Analysis of Bis(tetraphenylcyclopentadienyl)ruthenium(II)

    Get PDF
    Reaction of [Ru(p-cymene)Cl2]2 with K(η5-C5HPh4) in refluxing diglyme yields (η5-C5Ph4)2Ru in ca 50% yield. The complex was not susceptible to oxidation or reduction. (C5HPH4)2Ru crystallizes in the triclinic P1 space group with a = 8.549(4), b = 10.793(4), c = 12.842(5) Å, α = 65.98(3), β = 73.10(3), γ = 83.49(3)° and Z = 1. The least-squares data refined to R(F) = 3.53% and R(wF = 3.82% for the 3952 independent observed reflections with Fo ≥ 5σ(Fo). The metal-centroid distance is 1.832(2) Å and all other bond lengths and angles are similar to other octaphenylmetallocenes. 1H NMR analysis employing 2D J-resolved, COSY and low temperature techniques allowed assignment of all protons in the molecule. The motional processes of the phenyl groups are discussed

    Ground State and Excitations of Disordered Boson Systems

    Full text link
    After an introduction to the dirty bosons problem, we present a gaussian theory for the ground state and excitations. This approach is physically equivalent to the Bogoliubov approximation. We find that ODLRO can be destroyed with sufficient disorder. The density of states and localization of the elementary excitations are discussed. (To appear in JLTP Proceedings of the Conference on Condensed Bose Systems at the University of Minnesota, 1993.)Comment: 13 pages. (postscript file because of the figures inserted in the text.

    How many sigmas is the solar neutrino effect?

    Get PDF
    The minimal standard electroweak model can be tested by allowing all the solar neutrino fluxes, with undistorted energy spectra, to be free parameters in fitting the measured solar neutrino event rates, subject only to the condition that the total observed luminosity of the sun is produced by nuclear fusion. The rates of the five experiments prior to SNO (chlorine, Kamiokande, SAGE, GALLEX, Super-Kamiokande) cannot be fit by an arbitrary choice of undistorted neutrino fluxes at the level of 2.5 sigma (formally 99% C.L.). Considering just SNO and Super-Kamiokande, the discrepancy is at the 3.3 sigma level(10^{-3} C.L.). If all six experiments are fit simultaneously, the formal discrepancy increases to 4 sigma (7*10^{-5} C.L.). If the relative scaling in temperature of the nuclear reactions that produce 7Be and 8B neutrinos is taken into account, the formal discrepancy is at the 7.4 sigma level.Comment: 1 figure; related information at http://www.sns.ias.edu/~jn

    An Invitation to Higher Gauge Theory

    Get PDF
    In this easy introduction to higher gauge theory, we describe parallel transport for particles and strings in terms of 2-connections on 2-bundles. Just as ordinary gauge theory involves a gauge group, this generalization involves a gauge '2-group'. We focus on 6 examples. First, every abelian Lie group gives a Lie 2-group; the case of U(1) yields the theory of U(1) gerbes, which play an important role in string theory and multisymplectic geometry. Second, every group representation gives a Lie 2-group; the representation of the Lorentz group on 4d Minkowski spacetime gives the Poincar\'e 2-group, which leads to a spin foam model for Minkowski spacetime. Third, taking the adjoint representation of any Lie group on its own Lie algebra gives a 'tangent 2-group', which serves as a gauge 2-group in 4d BF theory, which has topological gravity as a special case. Fourth, every Lie group has an 'inner automorphism 2-group', which serves as the gauge group in 4d BF theory with cosmological constant term. Fifth, every Lie group has an 'automorphism 2-group', which plays an important role in the theory of nonabelian gerbes. And sixth, every compact simple Lie group gives a 'string 2-group'. We also touch upon higher structures such as the 'gravity 3-group' and the Lie 3-superalgebra that governs 11-dimensional supergravity.Comment: 60 pages, based on lectures at the 2nd School and Workshop on Quantum Gravity and Quantum Geometry at the 2009 Corfu Summer Institut

    IEA-Task 31 WAKEBENCH: Towards a protocol for wind farm flow model evaluation. Part 1: Flow-over-terrain models

    Get PDF
    The IEA Task 31 Wakebench is setting up a framework for the evaluation of wind farm flow models operating at microscale level. The framework consists on a model evaluation protocol integrated on a web-based portal for model benchmarking (www.windbench.net). This paper provides an overview of the building-block validation approach applied to flow-over-terrain models, including best practices for the benchmarking and data processing procedures for the analysis and qualification of validation datasets from wind resource assessment campaigns. A hierarchy of test cases has been proposed for flow-over-terrain model evaluation, from Monin-Obukhov similarity theory for verification of surface-layer properties, to the Leipzig profile for the near-neutral atmospheric boundary layer, to flow over isolated hills (Askervein and Bolund) to flow over mountaneous complex terrain (Alaiz). A summary of results from the first benchmarks are used to illustrate the model evaluation protocol applied to flow-over-terrain modeling in neutral conditions

    Cell Cycle Re-Entry and Mitochondrial Defects in Myc-Mediated Hypertrophic Cardiomyopathy and Heart Failure

    Get PDF
    While considerable evidence supports the causal relationship between increases in c-Myc (Myc) and cardiomyopathy as a part of a “fetal re-expression” pattern, the functional role of Myc in mechanisms of cardiomyopathy remains unclear. To address this, we developed a bitransgenic mouse that inducibly expresses Myc under the control of the cardiomyocyte-specific MHC promoter. In adult mice the induction of Myc expression in cardiomyocytes in the heart led to the development of severe hypertrophic cardiomyopathy followed by ventricular dysfunction and ultimately death from congestive heart failure. Mechanistically, following Myc activation, cell cycle markers and other indices of DNA replication were significantly increased suggesting that cell cycle-related events might be a primary mechanism of cardiac dysfunction. Furthermore, pathological alterations at the cellular level included alterations in mitochondrial function with dysregulation of mitochondrial biogenesis and defects in electron transport chain complexes I and III. These data are consistent with the known role of Myc in several different pathways including cell cycle activation, mitochondrial proliferation, and apoptosis, and indicate that Myc activation in cardiomyocytes is an important regulator of downstream pathological sequelae. Moreover, our findings indicate that the induction of Myc in cardiomyocytes is sufficient to cause cardiomyopathy and heart failure, and that sustained induction of Myc, leading to cell cycle re-entry in adult cardiomyocytes, represents a maladaptive response for the mature heart

    Guidelines for Diagnosis of Cystic Fibrosis in Newborns through Older Adults: Cystic Fibrosis Foundation Consensus Report

    Get PDF
    Newborn screening (NBS) for cystic fibrosis (CF) is increasingly being implemented and is soon likely to be in use throughout the United States, because early detection permits access to specialized medical care and improves outcomes. The diagnosis of CF is not always straightforward, however. The sweat chloride test remains the gold standard for CF diagnosis but does not always give a clear answer. Genotype analysis also does not always provide clarity; more than 1500 mutations have been identified in the CF transmembrane conductance regulator (CFTR) gene, not all of which result in CF. Harmful mutations in the gene can present as a spectrum of pathology ranging from sinusitis in adulthood to severe lung, pancreatic, or liver disease in infancy. Thus, CF identified postnatally must remain a clinical diagnosis. To provide guidance for the diagnosis of both infants with positive NBS results and older patients presenting with an indistinct clinical picture, the Cystic Fibrosis Foundation convened a meeting of experts in the field of CF diagnosis. Their recommendations, presented herein, involve a combination of clinical presentation, laboratory testing, and genetics to confirm a diagnosis of CF

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

    Get PDF
    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns
    corecore