72 research outputs found
Correspondence Between DGP Brane Cosmology and 5D Ricci-flat Cosmology
We discuss the correspondence between the DGP brane cosmology and 5D
Ricci-flat cosmology by letting their metrics equal each other. By this
correspondence, a specific geometrical property of the arbitrary integral
constant I in DGP metric is given and it is related to the curvature of 5D
bulk. At the same time, the relation of arbitrary functions and in
a class of Ricci-flat solutions is obtained from DGP brane metric.Comment: 8 pages, 1 figure, accepted by MPLA, added referenc
Dark Energy in Global Brane Universe
We discuss the exact solutions of brane universes and the results indicate
the Friedmann equations on the branes are modified with a new density term.
Then, we assume the new term as the density of dark energy. Using Wetterich's
parametrization equation of state (EOS) of dark energy, we obtain the new term
varies with the red-shift z. Finally, the evolutions of the mass density
parameter , dark energy density parameter and deceleration
parameter q_2 are studied.Comment: 8 pages,4 figure
Power-law cosmological solution derived from DGP brane with a brane tachyon field
By studying a tachyon field on the DGP brane model, in order to embed the 4D
standard Friedmann equation with a brane tachyon field in 5D bulk, the metric
of the 5D spacetime is presented. Then, adopting the inverse square potential
of tachyon field, we obtain an expanding universe with power-law on the brane
and an exact 5D solution.Comment: 8 pages, 1 figure, accepted by IJMP
Mining Medical Data: Bridging the Knowledge Divide
Due to the signi¯cant amount of data generated by modern medicine there is a growing reliance on tools such as data mining and knowledge discovery to help make sense and comprehend such data. The success of this process requires collaboration and interaction between such methods and medical professionals. Therefore an important question is: How can we strengthen the relationship between two traditionally separate fields (technology and medicine) in order to work simultaneously towards enhancing knowledge in modern medicine. To address this question, this study examines the application of data mining techniques to a large asthma medical dataset. A discussion introducing various methods for a smooth approach, straying from the `jack of all trades, master of none' to a modular cooperative approach for a successful outcome is pro-posed. The results of this study support the use of data mining as a useful tool and highlight the advantages on a global scale of closer relations between the two distinct fields. The exploration of CRISP methodology suggests that a `one methodology fits all approach' is not appropriate, but rather combines to create a hybrid holistic approach to data mining
Solutions to CDM Universe Derived from Global Brane Model
An exact solution of brane universe is studied and the result indicates that
Friedmann equations on the brane are modified with an extra term. This term can
play the role of dark energy and make the universe accelerate. In order to
derive the CDM Universe from this global brane model, the new
solutions are obtained to describe the manifold.Comment: 7 pages, no figure, accepted by MPL
The Real Scalar Field Equation for Nariai Black Hole in the 5D Schwarzschild-de Sitter Black String Space
The Nariai black hole, whose two horizons are lying close to each other, is
an extreme and important case in the research of black hole. In this paper we
study the evolution of a massless scalar field scattered around in 5D
Schwarzschild-de Sitter black string space. Using the method shown by Brevik
and Simonsen (2001) we solve the scalar field equation as a boundary value
problem, where real boundary condition is employed. Then with convenient
replacement of the 5D continuous potential by square barrier, the reflection
and transmission coefficients () are obtained. At last, we also compare
the coefficients with usual 4D counterpart.Comment: 10 pages,6 figures.To appear in Int. J. Mod. Phys.
Reconstruction of 5D Cosmological Model From Recent Observations
We use a parameterized equation of state (EOS) of dark energy to a 5D
Ricci-flat cosmological solution and suppose the universe contains two major
components: dark matter and dark energy. Using the recent observational
datasets: the latest 182 type Ia Supernovae Gold data, the 3-year WMAP CMB
shift parameter and the SDSS baryon acoustic peak, we obtain the best fit
values of the EOS and two major components' evolution. We find that the best
fit EOS crossing -1 in the near past , the present best fit value
of and for this model the universe experiences the acceleration at
about .Comment: 7 pages, 3 figs, Accept by IJMP
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