4,891 research outputs found
Modified theory of gravity and the history of cosmic evolution
A continuous transition from early Friedmann-like radiation era through to
late time cosmic acceleration passing through a long Friedmann-like matter
dominated era followed by a second phase of radiation era has been realized in
modified theory of gravity containing a combination of curvature squared term,
a linear term, a three-half term and an ideal fluid. Thus the history of cosmic
evolution is explained by modified theory of gravity singlehandedly. The second
phase of radiation-like era might provide an explanation to the hydrogen and
helium reionization at low redshift.Comment: 15 pages, 6 figures, Astrophys Space Sci (2014
EVALUATION OF THE ANTIOXIDANT ACTIVITY OF THE FLAVONOIDS ISOLATED FROM HELIOTROPIUM SINUATUM RESIN USING ORACFL, DPPH AND ESR METHODOLOGIES
Indexación: Web of Science; Scielo.The antioxidant capacity has been determined for a number of flavonoid compounds from Heliotropium sinuatum, a plant that grows in arid areas in the north of Chile. The methodologies used were: ORAC(FL) (oxygen radical absorbance capacity - fluorescein), DPPH (2,2-diphenyl-2-picrylhydrazyl) bleaching and electron spin resonance (ESR). These compounds were studied in homogeneous and heterogeneous media. The results showed that the 7-o-methyleriodictiol and 3-o-methylisorhamnetin are those with the highest antioxidant capacity.http://ref.scielo.org/m82cz
Implementation of an RNS based sequential NTT convolver.
Dept. of Electrical and Computer Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1982 .M623. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.Sc.)--University of Windsor (Canada), 1982
Electronic structure of MgB<SUB>2</SUB>
Results of ab initio electronic structure calculations on the compound MgB2 using the FPLAPW method employing GGA for the exchange-correlation energy are presented. Total energy minimization enables us to estimate the equilibrium volume, c/a ratio and the bulk modulus, all of which are in excellent agreement with experiment. We obtain the mass enhancement parameter by using our calculated D (E F) and the experimental specific heat data. The T c is found to be 24.7 K
Time in Quantum Gravity
The Wheeler-DeWitt equation in quantum gravity is timeless in character. In
order to discuss quantum to classical transition of the universe, one uses a
time prescription in quantum gravity to obtain a time contained description
starting from Wheeler-DeWitt equation and WKB ansatz for the WD wavefunction.
The approach has some drawbacks. In this work, we obtain the time-contained
Schroedinger-Wheeler-DeWitt equation without using the WD equation and the WKB
ansatz for the wavefunction. We further show that a Gaussian ansatz for SWD
wavefunction is consistent with the Hartle-Hawking or wormhole dominance
proposal boundary condition. We thus find an answer to the small scale boundary
conditions.Comment: 12 Pages, LaTeX, no figur
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