2,719 research outputs found
Hybridization between wild and cultivated potato species in the Peruvian Andes and biosafety implications for deployment of GM potatoes
The nature and extent of past and current hybridization between cultivated potato and wild relatives in nature is of interest to crop evolutionists, taxonomists, breeders and recently to molecular biologists because of the possibilities of inverse gene flow in the deployment of genetically-modified (GM) crops. This research proves that natural hybridization occurs in areas of potato diversity in the Andes, the possibilities for survival of these new hybrids, and shows a possible way forward in case of GM potatoes should prove advantageous in such areas
Motion and Trajectories of Particles Around Three-Dimensional Black Holes
The motion of relativistic particles around three dimensional black holes
following the Hamilton-Jacobi formalism is studied. It follows that the
Hamilton-Jacobi equation can be separated and reduced to quadratures in analogy
with the four dimensional case. It is shown that: a) particles are trapped by
the black hole independently of their energy and angular momentum, b) matter
alway falls to the centre of the black hole and cannot understake a motion with
stables orbits as in four dimensions. For the extreme values of the angular
momentum of the black hole, we were able to find exact solutions of the
equations of motion and trajectories of a test particle.Comment: Plain TeX, 9pp, IPNO-TH 93/06, DFTUZ 93/0
Chiral Anomaly Beyond Lorentz Invariance
The chiral anomaly in the context of an extended standard model with minimal
Lorentz invariance violation is studied. Taking into account bounds from
measurements of the speed of light, we argue that the chiral anomaly and its
consequences are general results valid even beyond the relativistic symmetry.Comment: Final version. To be published in PR
On the Initial Singularity Problem in Two Dimensional Quantum Cosmology
The problem of how to put interactions in two-dimensional quantum gravity in
the strong coupling regime is studied. It shows that the most general
interaction consistent with this symmetry is a Liouville term that contain two
parameters satisfying the algebraic relation in order to assure the closure of the diffeomorphism algebra. The model is
classically soluble and it contains as general solution the temporal
singularity. The theory is quantized and we show that the propagation amplitude
fall tozero in . This result shows that the classical singularities
are smoothed by quantum effects and the bing-bang concept could be considered
as a classical extrapolation instead of a physical concept.Comment: 9pp, Revtex 3.0. New references added. To appear in Phys. Rev.
Null Branes in String Theory Backgrounds
We consider null bosonic p-branes moving in curved space-times and develop a
method for solving their equations of motion and constraints, which is suitable
for string theory backgrounds. As an application, we give an exact solution for
such background in ten dimensions.Comment: 11 pages, LaTeX. Final version, to appear in Phys. Rev.
SU(2) Kinetic Mixing Terms and Spontaneous Symmetry Breaking
The non-abelian generalization of the Holdom model --{\it i.e.} a theory with
two gauge fields coupled to the kinetic mixing term -- is considered. Contrarily to the abelian case, the group
structure is explicitly broken to . For SU(2) this fact implies
that the residual gauge symmetry as well as the Lorentz symmetry is
spontaneusly broken. We show that this mechanism provides of masses for the
involved particles. Also, the model presents instanton solutions with a
redefined coupling constant.Comment: 9pp. typos and clarifications are adde
High Definition Liposuction: A Challenge for a Perfect Body Contouring
During the last decades, the plastic surgery field has made important advances in terms of clinical results and developing new surgical techniques, minimizing complications and reducing the mortality rates. An innovative and new technique is called High Definition LipoSculture. This is an advanced sculpting technique that creates an athletic and sculpted appearance. The aim of this chapter is to review the principal concepts that involve this technique and describe its clinical application. An electronic literature review was conducted in order to find the most recent medical literature published in this field. Keywords used were plastic surgery, liposuction, body contouring, aesthetic medicine, and surgical procedure. High definition liposuction procedures should be considered revolutionary in the plastic surgery field
Money And Research Revolution In The Biomedical Industry: Is It A Real Race?
Medicine is a dynamic science and discipline, which arise from the human need to face the suffering, pain and give hopes for better life. Since its inception, medicine has entered a career development that has brought great advances in science. Medicine has become one of the most promising businesses in the economic field, and up today, and it is considered one of the greatest science futures with wide range of prospects
Aharonov-Casher effect for spin one particles in a noncommutative space
In this work the Aharonov-Casher (AC) phase is calculated for spin one
particles in a noncommutative space. The AC phase has previously been
calculated from the Dirac equation in a noncommutative space using a gauge-like
technique [17]. In the spin-one, we use kemmer equation to calculate the phase
in a similar manner. It is shown that the holonomy receives non-trivial
kinematical corrections. By comparing the new result with the already known
spin 1/2 case, one may conjecture a generalized formula for the corrections to
holonomy for higher spins.Comment: 9 page
Multi-Black-Holes in Three Dimensions
We construct time-dependent multi-centre solutions to three-dimensional
general relativity with zero or negative cosmological constant. These solutions
correspond to dynamical systems of freely falling black holes and conical
singularities, with a multiply connected spacetime topology. Stationary
multi-black-hole solutions are possible only in the extreme black hole case.Comment: 8 pages, \LaTex, 4 figures (available on request), GCR 94/02/0
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