101,431 research outputs found
Norm minima in certain Siegel leaves
In this paper we shall illustrate that each polytopal moment-angle complex
can be understood as the intersection of the minima of corresponding Siegel
leaves and the unit sphere, with respect to the maximum norm. Consequently, an
alternative proof of a rigidity theorem of Bosio and Meersseman is obtained; as
piecewise linear manifolds, polytopal real moment-angle complexes can be
smoothed in a natural way.Comment: 21 page
A Holographic P-wave Superconductor Model
We study a holographic p-wave superconductor model in a four dimensional
Einstein-Maxwell-complex vector field theory with a negative cosmological
constant. The complex vector field is charged under the Maxwell field. We solve
the full coupled equations of motion of the system and find black hole
solutions with the vector hair. The vector hairy black hole solutions are dual
to a thermal state with the U(1) symmetry as well as the spatial rotational
symmetry breaking spontaneously. Depending on two parameters, the mass and
charge of the vector field, we find a rich phase structure: zeroth order, first
order and second order phase transitions can happen in this model. We also find
"retrograde condensation" in which the hairy black hole solution exists only
for the temperatures above a critical value with the free energy much larger
than the black hole without hair. We construct the phase diagram for this
system in terms of the temperature and charge of the vector field.Comment: v3: 26 pages, 15 figures, references added, extra arguments added, to
appear in JHE
Numerical Regularized Moment Method of Arbitrary Order for Boltzmann-BGK Equation
We introduce a numerical method for solving Grad's moment equations or
regularized moment equations for arbitrary order of moments. In our algorithm,
we do not need explicitly the moment equations. As an instead, we directly
start from the Boltzmann equation and perform Grad's moment method \cite{Grad}
and the regularization technique \cite{Struchtrup2003} numerically. We define a
conservative projection operator and propose a fast implementation which makes
it convenient to add up two distributions and provides more efficient flux
calculations compared with the classic method using explicit expressions of
flux functions. For the collision term, the BGK model is adopted so that the
production step can be done trivially based on the Hermite expansion. Extensive
numerical examples for one- and two-dimensional problems are presented.
Convergence in moments can be validated by the numerical results for different
number of moments.Comment: 33 pages, 13 figure
Genetic improvement of the herbivorous blunt snout bream (Megalobrama amblycephala)
Selection experiments with the herbivorous blunt snout bream or Wuchang bream (Megalobrama amblycephala) were started in 1985. Mass selection for size and length/depth ratio resulted in a significant increase in growth and better shape, while inbreeding led to a significant decrease in growth. The total selection ratio from fry to mature brooders was about 0.03 per cent per generation. In the grow out stage, the average daily body weight gains of two lines of fifth generation (F5) fish were 29 per cent and 20 per cent respectively more than the control group, with an average of 5.8 per cent and 4 per cent improvements per generation, respectively. The body was 4 per cent deeper in ratio of standard length/body depth. The effects of inbreeding were examined by crossing full-sibs, the offspring of which were kept without selection. The third generation inbred fish showed 17 per cent lower growth as compared to the control group, with an average of 7.5 per cent per generation. The results demonstrate that selection is a powerful tool to improve the economic traits of the blunt snout bream, but inbreeding can rapidly lead to a reduction in performance. In 2000, the 6th generation of selected bream was certified by the Chinese Ministry of Agriculture as a good breed for aquaculture
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