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匹配条件: “Sivaram G” ,找到相关结果约189309条。
Cosmic repulsion in presence of matter
G. Sudhakaran,C. Sivaram
Physics , 2001,
Abstract: A basic problem that confronts the standard cosmological models is the problem of initial singularity characterised by infinite material density, infinite temperature and infinite spacetime curvature. The inevitable existence of such a phase of the universe may be considered to be one of the major drawbacks of Einstein's field equations. To some extent inflation models ameliorate this. In the present work we postulate that whenever matter (radiation) arises in flat spacetime, it introduces curvature and causes a repulsive interaction to develop. A modified energy momentum tensor is introduced towards this end, which invokes the temperature, entropy and a cosmic scalar field. This redefinition of the energy momentum distribution when applied to the early universe dynamics has the effect of producing a non-singular initial behaviour. the repulsive interaction introduces some features of an accelarating universe. In this model all cosmological parameters are mathematically well behaved. There is no flatness problem. Temperature at the beginning of this universe is 10^32 kelvin.
Bioencapsulation strategy and highly unsaturated fatty acids (HUFA) enrichment in Artemia franciscana nauplii by using marine trash fish Odonus niger liver oil
G Immanuel, T Citarasu, V Sivaram, VS Shankar, A Palavesam
African Journal of Biotechnology , 2007,
Abstract: To investigate the maximum accumulation of highly unsaturated fatty acids (HUFA) in Artemia franciscana nauplii through bioencapsulation process, five different concentrations (0 - 4%) of emulsified Odonus niger liver oil were prepared. The prepared emulsions were used to enrich A. franciscana at different time intervals of 6, 12, 18 and 24 h. After the enrichment period, the fatty acid composition of the nauplii were analysed and estimated individually along with freshly hatched A. franciscana and O. niger liver oil. The HUFA content such as linoleic (18: 2n-6), linolenic (18: 3n-3), arachidonic (20: 4n-3 + n-6), eicosapentaenoic (20: 5-n3) and docosahexaenoic (22: 6n-3) acids were 12.87, 0.21, 2.66, 2.86 and 2.30% dry weight (DW), respectively, in O. niger liver oil, and 8.60, 17.20, 1.80, 2.40 and 0.1% DW, respectively, in freshly hatched A. franciscana. During 6 – 24 h of enrichment period, all the above HUFA increased considerably from 8.76 to 10.84, 17.24 to 23.84, 1.16 to 3.98, 2.45 to 5.88 and 0.30 to 2.69% DW, respectively. The increase in the level of individual HUFA of A. franciscana enriched with various concentrations of emulsified liver oil at different time durations showed a positive linear relationship and the correlation coefficient obtained were statistically significant (P< 0.05).
Primary sclerosing cholangitis and Biliary cirrhosis associated with Ulcerative colitis
Avinash Bardia,Santosh K. Tiwari,Sivaram G,Farha Anjum
Journal of Medical and Allied Sciences , 2011,
Abstract: Primary sclerosing cholangitis and Ulcerative colitis are caused by progressive inflammation of the bile duct and large intestine respectively. The existence of any plausible association between Primary sclerosing cholangitis and Ulcerative colitis remains highly elusive. Little is known about the incidence and prevalence of primary sclerosing cholangitis with concomitant Ulcerative colitis in the Indian subcontinent. We report a case of Primary sclerosing cholangitis with long standing Ulcerative colitis which later also developed Primary biliary cirrhosis.
Possible Constraints on Neutron Electric Dipole Moment from Pulsar Radiation
C. Sivaram
Physics , 2010,
Abstract: Even if only a small fraction of neutron dipole moments are aligned in a neutron star, observed pulsar radiation loses provide a stringent limit on the neutron electric dipole moment of <10-29 ecm, more stringent than best current experimental limits.
A Brief History of Dark Energy
C Sivaram
Physics , 2008, DOI: 10.1007/s10509-008-9952-y
Abstract: Gurzadyan-Xue Dark Energy was derived in 1986 (twenty years before the paper of Gurzadyan-Xue). The paper by the present author, titled The Planck Length as a Cosmological Constant, published in Astrophysics Space Science, Vol. 127, p.133-137, 1986 contains the formula claimed to have been derived by Gurzadyan-Xue (in 2003).
Black Holes and the LHC
C Sivaram
Physics , 2008,
Abstract: The relevant physics for the possible formation of black holes in the LHC is discussed.
Hydrodynamics, horizons, holography and black hole entropy
C. Sivaram
Physics , 2011,
Abstract: The usual discussions about black hole dynamics involve analogies with laws of thermodynamics especially in connection with black hole entropy and the associated holographic principle. We explore complementary aspects involving hydrodynamics of the horizon geometry through the membrane paradigm. New conceptual connections complementing usual thermodynamic arguments suggest deep links between diverse topics like black hole decay, quantum circulation and viscosity. Intriguing connections between turbulence cascades, quantum diffusion via quantum paths following Fokker- Planck equation and Hawking decay also result from this combination of thermodynamic and hydrodynamic analogies to black hole dynamics.
What is Special About the Planck Mass?
C. Sivaram
Physics , 2007,
Abstract: Planck introduced his famous units of mass, length and time a hundred years ago. The many interesting facets of the Planck mass and length are explored. The Planck mass ubiquitously occurs in astrophysics, cosmology, quantum gravity, string theory, etc. Current aspects of its implications for unification of fundamental interactions, energy dependence of coupling constants, dark energy, etc. are discussed.
A simple way to speedup Gauss Elimination
Sivaram Ambikasaran
Mathematics , 2011,
Abstract: This article looks at a simple modification to speedup the conventional Gauss Elimination. The proposed modification speeds up the conventional Gauss Elimination by a factor of nearly 9/7 (in the asymptotic limit).
Generalized Rybicki Press algorithm
Sivaram Ambikasaran
Computer Science , 2014,
Abstract: This article discusses a more general and numerically stable Rybicki Press algorithm, which enables inverting and computing determinants of covariance matrices, whose elements are sums of exponentials. The algorithm is true in exact arithmetic and relies on introducing new variables and corresponding equations, thereby converting the matrix into a banded matrix of larger size. Linear complexity banded algorithms for solving linear systems and computing determinants on the larger matrix enable linear complexity algorithms for the initial semi-separable matrix as well. Benchmarks provided illustrate the linear scaling of the algorithm.

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