17,303 research outputs found
Non-equilibrium ionization around clouds evaporating in the interstellar medium
It is of prime importance for global models of the interstellar medium to know whether dense clouds do or do not evaporate in the hot coronal gas. The rate of mass exchanges between phases depends very much on that. McKee and Ostriker's model, for instance, assumes that evaporation is important enough to control the expansion of supernova remnants, and that mass loss obeys the law derived by Cowie and McKee. In fact, the geometry of the magnetic field is nearly unknown, and it might totally inhibit evaporation, if the clouds are not regularly connected to the hot gas. Up to now, the only test of the theory is the U.V. observation (by the Copernicus and IUE satellites) of absorption lines of ions such as OVI or NV, that exist at temperatures of a few 100,000 K typical of transition layers around evaporating clouds. Other means of testing the theory are discussed
Neutrino Masses in Split Supersymmetry
We investigate the possibility to generate neutrino masses in the context of
Split supersymmetric scenarios where all sfermions are very heavy. All relevant
contributions coming from the R-parity violating terms to the neutrino mass
matrix up to one-loop level are computed, showing the importance of the Higgs
one-loop corrections. We conclude that it is not possible to generate all
neutrino masses and mixings in Split SUSY with bilinear R-Parity violating
interactions. In the case of Partial Split SUSY the one-loop Higgs
contributions are enough to generate the neutrino masses and mixings in
agreement with the experiment. In the context of minimal SUSY SU(5) we find new
contributions which help us to generate neutrino masses in the case of Split
SUSY.Comment: 33 pages, 6 figures, to appear in Physical Review
Energy dependence of the quark masses and mixings
The one loop Renormalization Group Equations for the Yukawa couplings of
quarks are solved. From the solution we find the explicit energy dependence on
of the evolution of the {\em down} quark masses from
the grand unification scale down to the top quark mass . These results
together with the earlier published evolution of the {\em up} quark masses
completes the pattern of the evolution of the quark masses. We also find the
energy dependence of the absolute values of the Cabibbo-Kobayashi-Maskawa (CKM)
matrix . The interesting property of the evolution of the CKM matrix
and the ratios of the quark masses: and is that
they all depend on through only one function of energy .Comment: Talk presented at the IX Mexican School on Particles and Fields,
August 9-19, Metepec, Pue., Mexico. To be published in the AIP Conference
Proceedings. 5 pages and 1 eps figure included in the tex
Iuris civilis notae ad vestem seu textile pertinentes : Notes on dress in roman property law.
Roman law considered clothing as a res, as something that could be the object of legal relations, specifically as a res corporalis, a res quae usu consumatur, a res nec mancipi and a res mobilis. These characteristics of vestis as a res were of great practical importance and to a large extent determined the legal regime applicable to the personal property of this type of goods, specifically in regard to possession, right of usufruct and modes of acquiring ownership, as usucapio, occupatio, specificatio and some cases of accessio affecting movables goods: textura and tinctura
Discrete model for laser driven etching and microstructuring of metallic surfaces
We present a unidimensional discrete solid-on-solid model evolving in time
using a kinetic Monte Carlo method to simulate micro-structuring of kerfs on
metallic surfaces by means of laser-induced jet-chemical etching. The precise
control of the passivation layer achieved by this technique is responsible for
the high resolution of the structures. However, within a certain range of
experimental parameters, the microstructuring of kerfs on stainless steel
surfaces with a solution of shows periodic ripples,
which are considered to originate from an intrinsic dynamics. The model mimics
a few of the various physical and chemical processes involved and within
certain parameter ranges reproduces some morphological aspects of the
structures, in particular ripple regimes. We analyze the range of values of
laser beam power for the appearance of ripples in both experimental and
simulated kerfs. The discrete model is an extension of one that has been used
previously in the context of ion sputtering and is related to a noisy version
of the Kuramoto-Sivashinsky equation used extensively in the field of pattern
formation.Comment: Revised version. Etching probability distribution and new simulations
adde
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