2,434 research outputs found

    Delta rho pi interaction leading to N* and Delta* resonances

    Full text link
    We have performed a calculation for the three body Δρπ\Delta \rho \pi system by using the fixed center approximation to Faddeev equations, taking the interaction between Δ\Delta and ρ\rho, Δ\Delta andπ\pi, and ρ\rho and π\pi from the chiral unitary approach. We find several peaks in the modulus squared of the three-body scattering amplitude, indicating the existence of resonances, which can be associated to known I=1/2,3/2I=1/2, 3/2 and JP=1/2+,3/2+J^P=1/2^+, 3/2^+ and 5/2+5/2^+ baryon states.Comment: Presented at the 21st European Conference on Few-Body Problems in Physics, Salamanca, Spain, 30 August - 3 September 201

    Портрет современного менеджера в контексте информационных систем управления предприятием

    Get PDF
    The article systematizes the management functions in the context of corporate information systems (CIS) with the selection of the set of tasks and the system of indicators in the context of each function. Problems of the practical use of CIS by managers of Belarusian enterprises are formulated and the qualification requirements for managers of CIS within the implemented functions are substantiated. В статье проведена систематизация функций управления применительно к корпоративным информационным системам (КИС) с выделением набора задач и системы показателей в разрезе каждой функции, сформулированы проблемы практического использования КИС менеджерами белорусских предприятий, обоснованы квалификационные требования к менеджерам-пользователям КИС внутри реализуемых функций.

    Photoemission spectra of Sr2CuO2Cl2{\rm Sr_2 Cu O_2 Cl_2}: a theoretical analysis

    Full text link
    Recent angle resolved photoemission (ARPES) results for the insulating cuprate Sr2CuO2Cl2{\rm Sr_2 Cu O_2 Cl_2} have provided the first experimental data which can be directly compared to the (theoretically) well--studied problem of a single hole propagating in an antiferromagnet. The ARPES results reported a small bandwidth, providing evidence for the existence of strong correlations in the cuprates. However, in the same experiment some discrepancies with the familiar 2D tJ{\rm t-J} model were also observed. Here we discuss a comparison between the ARPES results and the quasiparticle dispersion of both (i) the ttJ{\rm t-t'-J} Hamiltonian and (ii) the three--band Hubbard model in the strong--coupling limit. Both model Hamiltonians show that the experimentally observed one--hole band structure can be approximately reproduced using reasonable values for t{\rm t'}, or the direct oxygen hopping amplitude tpp{\rm t_{pp}}.Comment: 11 pages, RevTex version 3.0, 3 postscript figures, LaTeX file and figures have been uuencoded

    Hypovitaminosis D and cardiometabolic risk factors in adolescents with severe obesity

    Get PDF
    Background/Objectives. Obesity is associated with cardiometabolic risk factors and with Vitamin D deficiency. The aim of this study was to examine the relationship between 25(OH)D concentrations and cardiometabolic risk factors in adolescents with severe obesity. Subjects/Methods. A cross-sectional clinical assessment (body mass index, fat mass index, fat-free mass index, waist-to-height ratio, and blood pressure) and metabolic study (triglycerides, total cholesterol, HDL-C, LDL-C, glucose, insulin, HOMA-IR, leptin, calcium, phosphorous, calcidiol, and PTH) were carried out in 236 adolescents diagnosed with severe obesity (BMI z-score > 3.0, 99th percentile), aged 10.2–15.8 years. The criteria of the US Endocrine Society were used for the definition of Vitamin D status. Results. Subjects with Vitamin D deficiency had significantly elevated values (p < 0.05) for BMI z-score, waist circumference, waist z-score, body fat percentage, fat mass index, systolic and diastolic blood pressure, total cholesterol, triglycerides, LDL-C, insulin, HOMA-IR, leptin, and PTH than subjects with normal Vitamin D status. There was a significant negative correlation (p < 0.05) of serum 25(OH)D levels with body fat percentage, FMI, systolic BP, total cholesterol, triglyceride, LDL-C, glucose, insulin, HOMA-IR, leptin, and PTH. Conclusions. Low Vitamin D levels in adolescents with severe obesity were significantly associated with some cardiometabolic risk factors, including body mass index, waist circumference, fat mass index, high blood pressure, impaired lipid profile, and insulin resistance

    Casimir Effect, Achucarro-Ortiz Black Hole and the Cosmological Constant

    Get PDF
    We treat the two-dimensional Achucarro-Ortiz black hole (also known as (1+1) dilatonic black hole) as a Casimir-type system. The stress tensor of a massless scalar field satisfying Dirichlet boundary conditions on two one-dimensional "walls" ("Dirichlet walls") is explicitly calculated in three different vacua. Without employing known regularization techniques, the expression in each vacuum for the stress tensor is reached by using the Wald's axioms. Finally, within this asymptotically non-flat gravitational background, it is shown that the equilibrium of the configurations, obtained by setting Casimir force to zero, is controlled by the cosmological constant.Comment: 20 pages, LaTeX, minor corrections, comments and clarifications added, version to appear in Phys. Rev.

    Study of the f2(1270)f_2(1270), f2(1525)f_2'(1525), f0(1370)f_0(1370) and f0(1710)f_0(1710) in the J/ψJ/\psi radiative decays

    Get PDF
    In this paper we present an approach to study the radiative decay modes of the J/ψJ/\psi into a photon and one of the tensor mesons f2(1270)f_2(1270), f2(1525)f'_2(1525), as well as the scalar ones f0(1370)f_0(1370) and f0(1710)f_0(1710). Especially we compare predictions that emerge from a scheme where the states appear dynamically in the solution of vector meson--vector meson scattering amplitudes to those from a (admittedly naive) quark model. We provide evidence that it might be possible to distinguish amongst the two scenarios, once improved data are available.Comment: The large Nc argument improved; version published in EPJA

    Radiative decays of light vector mesons in a quark level linear sigma model

    Get PDF
    We calculate the P0 to gamma gamma, V0 to P0 gamma and V0to V'0 gamma gamma decays in the framework of a U(3)xU(3) linear sigma model which includes constituent quarks. For the first two decays this approach improves results based on the anomalous Wess-Zumino term, with contributions due to SU(3) symmetry breaking and vector mixing. The phi to (omega,rho) gamma gamma decays are dominated by resonant eta' exchange . Our calculation for the later decays improves and update similar calculations in the -closely related- framework of vector meson dominance. We obtain BR(phi to rho gamma gamma)=2.5x10^{-5} and BR(phi to omega gamma gamma)=2.8x10^{-6} within the scope of the high-luminosity phi factories.Comment: 8 pages, submitted to Phys. Rev.

    The computational fluid dynamics modelling of the autorotation of square, flat plates

    Get PDF
    This paper examines the use of a coupled Computational Fluid Dynamics (CFD) – Rigid Body Dynamics (RBD) model to study the fixed-axis autorotation of a square flat plate. The calibration of the model against existing wind tunnel data is described. During the calibration, the CFD models were able to identify complex period autoration rates, which were attributable to a mass eccentricity in the experimental plate. The predicted flow fields around the autorotating plates are found to be consistent with existing observations. In addition, the pressure coefficients from the wind tunnel and computational work were found to be in good agreement. By comparing these pressure distributions and the vortex shedding patterns at various stages through an autorotation cycle, it was possible to gain important insights into the flow structures that evolve around the plate. The CFD model is also compared against existing correlation functions that relate the mean tip speed ratio of the plate to the aspect ratio, thickness ratio and mass moment of inertia of the plate. Agreement is found to be good for aspect ratios of 1, but poor away from this value. However, other aspects of the numerical modelling are consistent with the correlations
    corecore