1,859 research outputs found

    3D Bio-convective nanofluid Bödewadt slip flow comprising gyrotactic microorganisms over a stretched stationary disk with modified Fourier law

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    The renowned Bödewadt flow problem is considered here for the case of Bio-convective nanofluid flow encompassing gyrotactic microorganisms over a stationary disk. The flow is initiated owing to the rotation of water-based nanofluid which is at a large distance from an immovable disk. The analysis is performed with modified Fourier law in a Darcy-Forchheimer spongy media accompanied by slip and zero mass flux conditions at the surface. The subject Bödewadt nanofluid flow is considered with gyrotactic microorganisms and Cattaneo-Christov (C-C) heat flux effects for the first time. Conformist Von Kármán relations are affianced to attain a similar governing system of differential equations. An efficient MATLAB software-based numerical scheme bvp4c is employed to address the envisaged novel mathematical model. An outstanding synchronization is achieved when a comparative statement is formulated in a limiting case. Outcomes of the proclaimed parameters versus involved distributions are discussed with logical reasoning. It is comprehended that the microorganism density boundary layer is prominent for higher values of the Peclet number. Furthermore, it is remarked that the fluid temperature is diminished for significant values of the thermal relaxation time

    Hawking radiation from the Schwarzschild black hole with a global monopole via gravitational anomaly

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    Hawking flux from the Schwarzschild black hole with a global monopole is obtained by using Robinson and Wilczek's method. Adopting a dimension reduction technique, the effective quantum field in the (3+1)--dimensional global monopole background can be described by an infinite collection of the (1+1)--dimensional massless fields if neglecting the ingoing modes near the horizon, where the gravitational anomaly can be cancelled by the (1+1)--dimensional black body radiation at the Hawking temperature.Comment: 4 pages, no figure, 3nd revsion with one reference adde

    Effects of Changes in Moisture Source and the Upstream Rainout on Stable Isotopes in Precipitation – A Case Study in Nanjing, Eastern China

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    In the Asian monsoon region, variations in the stable isotopic composition of speleothems have often been attributed to the amount effect . However, an increasing number of studies suggest that the amount effect in local precipitation is insignificant or even non-existent. To explore this issue further, we examined the variability of daily stable isotopic composition (δ18O) in precipitation from September 2011 to November 2014 in Nanjing, eastern China. We found that intra-seasonal variations of δ18O during summer were not significantly correlated with local rainfall amount but could be linked to changes in the moisture source location and rainout processes in the source regions. Our findings suggest that the stable isotopes in summer precipitation could signal the location shift of precipitation source regions in the inter-tropical convergence zone (ITCZ) over the course of the monsoon season. As a result, changes in moisture source location and upstream rainout effect should be taken into account when interpreting the stable isotopic composition of speleothems in the Asian monsoon region. In addition, the temperature effect on isotopic variations in non-monsoonal precipitation should also be considered because precipitation in the non-monsoon season accounts for about half of its annual precipitation

    A Cosmology-Independent Calibration of Gamma-Ray Burst Luminosity Relations and the Hubble Diagram

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    An important concern in the application of gamma-ray bursts (GRBs) to cosmology is that the calibration of GRB luminosity/energy relations depends on the cosmological model, due to the lack of a sufficient low-redshift GRB sample. In this paper, we present a new method to calibrate GRB relations in a cosmology-independent way. Since objects at the same redshift should have the same luminosity distance and since the distance moduli of Type Ia supernovae (SNe Ia) obtained directly from observations are completely cosmology independent, we obtain the distance modulus of a GRB at a given redshift by interpolating from the Hubble diagram of SNe Ia. Then we calibrate seven GRB relations without assuming a particular cosmological model and construct a GRB Hubble diagram to constrain cosmological parameters. From the 42 GRBs at 1.4<z≤6.61.4<z\le6.6, we obtain ΩM=0.25−0.05+0.04\Omega_{\rm M}=0.25_{-0.05}^{+0.04}, ΩΛ=0.75−0.04+0.05\Omega_{\Lambda}=0.75_{-0.04}^{+0.05} for the flat Λ\LambdaCDM model, and for the dark energy model with a constant equation of state w0=−1.05−0.40+0.27w_0=-1.05_{-0.40}^{+0.27}, which is consistent with the concordance model in a 1-σ\sigma confidence region.Comment: 7 pages, 3 figures, 1 table, now matches the editorially revised version; accepted for publication in ApJ (vol 685)

    Description of 178^{178}Hfm2^{m2} in the constrained relativistic mean field theory

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    The properties of the ground state of 178^{178}Hf and the isomeric state 178^{178}Hfm2^{m2} are studied within the adiabatic and diabatic constrained relativistic mean field (RMF) approaches. The RMF calculations reproduce well the binding energy and the deformation for the ground state of 178^{178}Hf. Using the ground state single-particle eigenvalues obtained in the present calculation, the lowest excitation configuration with Kπ=16+K^\pi=16^+ is found to be ν(7/2−[514])−1(9/2+[624])1\nu(7/2^-[514])^{-1}(9/2^+[624])^{1} π(7/2+[404])−1(9/2−[514])1\pi(7/2^+[404])^{-1}(9/2^-[514])^{1}. Its excitation energy calculated by the RMF theory with time-odd fields taken into account is equal to 2.801 MeV, i.e., close to the 178^{178}Hfm2^{m2} experimental excitation energy 2.446 MeV. The self-consistent procedure accounting for the time-odd component of the meson fields is the most important aspect of the present calculation.Comment: 12 pages(preprint), 2 figures, 1 tabl
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