22 research outputs found
Applied genetics of tilapias
This paper reviews the successes and failures of genetic experiments on tilapias and points to various characteristics of tilapias, which require improvement for increased yields.Tilapia culture, Genetics, Aquaculture techniques Tilapia, Sarotherodon
A note on accelerating cosmologies from compactifications and S-branes
We give a simple interpretation of the recent solutions for cosmologies with
a transient accelerating phase obtained from compactification in hyperbolic
manifolds, or from S-brane solutions of string/M-theory. In the
four-dimensional picture, these solutions correspond to bouncing the radion
field off its exponential potential. Acceleration occurs at the turning point,
when the radion stops and the potential energy momentarily dominates. The
virtues and limitations of these approaches become quite transparent in this
interpretation.Comment: 9 pages, 1 figure. References adde
Cosmological solutions in multidimensional model with multiple exponential potential
A family of cosmological solutions with Ricci-flat spaces in the
theory with several scalar fields and multiple exponential potential is
obtained when coupling vectors in exponents obey certain relations. Two
subclasses of solutions with power-law and exponential behaviour of scale
factors are singled out. It is proved that power-law solutions may take place
only when coupling vectors are linearly independent and exponential dependence
occurs for linearly dependent set of coupling vectors. A subfamily of solutions
with accelerated expansion is singled out. A generalized isotropization
behaviours of certain classes of general solutions are found. In quantum case
exact solutions to Wheeler-DeWitt equation are obtained and special "ground
state" wave functions are considered.Comment: 22 pages, 1 figur
Gutzwiller-Correlated Wave Functions: Application to Ferromagnetic Nickel
Ferromagnetic Nickel is the most celebrated iron group metal with pronounced
discrepancies between the experimental electronic properties and predictions of
density functional theories. In this work, we show in detail that the recently
developed multi-band Gutzwiller theory provides a very good description of the
quasi-particle band structure of nickel. We obtain the correct exchange
splittings and we reproduce the experimental Fermi-surface topology. The
correct (111)-direction of the magnetic easy axis and the right order of
magnitude of the magnetic anisotropy are found. Our theory also reproduces the
experimentally observed change of the Fermi-surface topology when the magnetic
moment is oriented along the (001)-axis. In addition to the numerical study, we
give an analytical derivation for a much larger class of variational
wave-functions than in previous investigations. In particular, we cover cases
of superconductivity in multi-band lattice systems.Comment: 35 pages, 3 figure
Accelerating Universes in String Theory via Field Redefinition
We study cosmological solutions in the effective heterotic string theory with
-correction terms in string frame. It is pointed out that the
effective theory has an ambiguity via field redefinition and we analyze
generalized effective theories due to this ambiguity. We restrict our analysis
to the effective theories which give equations of motion of second order in the
derivatives, just as "Galileon" field theory. This class of effective actions
contains two free coupling constants. We find de Sitter solutions as well as
the power-law expanding universes in our four-dimensional Einstein frame. The
accelerated expanding universes are always the attractors in the present
dynamical system.Comment: 22 pages, 3 figures, some additional formulae adde