722 research outputs found
Kaon condensation in neutron stars and high density behaviour of nuclear symmetry energy
We study the influence of a high density behaviour of the nuclear symmetry
energy on a kaon condensation in neutron stars. We find that the symmetry
energy typical for several realistic nuclear potentials, which decreases at
high densities, inhibits kaon condensation for weaker kaon-nucleon couplings.
There exists a threshold coupling above which the kaon condensate forms at
densities exceeding some critical value. This is in contrast to the case of
rising symmetry energy, as e.g. for relativistic mean field models, when the
kaon condensate can form for any coupling at a sufficiently high density.
Properties of the condensate are also different in both cases.Comment: 12 pages, 7 figures, Acta Phys. Pol. B in pres
Internationale bepalingen ter voorkoming van aanvaringen op zee: K.B. houdende Politie- en Scheepvaartreglement voor de Belgische territoriale zee, de havens en de stranden van de Belgische kust
Isospin breaking in the pion-nucleon scattering lengths
We analyze isospin breaking through quark mass differences and virtual photons in the pion-nucleon scattering lengths in all physical channels in the framework of covariant baryon chiral perturbation theory (C) 2009 Elsevier B.V. All rights reserved
Influencia de los tensides en la liberación de las sustancias medicinales de los geles hidrófilos: influencia del polisorbato 20 y polisorbato 80 en la liberación del hidrocortisona de los geles hidrófilos
El proceso de liberación de hidrocortisona de los hidrogeles con la adición del 1% y del 3% del polisorbato 20o polisorbato 80, en la presencia de propilenglicol - 1,2 o PEG 200, tiene dos fases. Durante la primera fase lasvelocidades de liberación son más altas, comparando con la segunda fase. La segunda fase de liberación correspondea la cinética de primer orden. Los periodos de semiliberación en el transcurso de esta fase oscilan entre15,67 y 23,50
Reconciling threshold and subthreshold expansions for pion-nucleon scattering
Heavy-baryon chiral perturbation theory (ChPT) at one loop fails in relating
the pion-nucleon amplitude in the physical region and for subthreshold
kinematics due to loop effects enhanced by large low-energy constants. Studying
the chiral convergence of threshold and subthreshold parameters up to fourth
order in the small-scale expansion, we address the question to what extent this
tension can be mitigated by including the as an explicit degree
of freedom and/or using a covariant formulation of baryon ChPT. We find that
the inclusion of the indeed reduces the low-energy constants to more
natural values and thereby improves consistency between threshold and
subthreshold kinematics. In addition, even in the -less theory the
resummation of corrections in the covariant scheme improves the results
markedly over the heavy-baryon formulation, in line with previous observations
in the single-baryon sector of ChPT that so far have evaded a profound
theoretical explanation.Comment: 10 pages, 4 tables, Mathematica notebook with the analytic
expressions for threshold and subthreshold parameters included as
supplementary material; journal versio
Isospin mixing in the nucleon and 4He and the nucleon strange electric form factor
In order to isolate the contribution of the nucleon strange electric form
factor to the parity-violating asymmetry measured in 4He(\vec e,e')4He
experiments, it is crucial to have a reliable estimate of the magnitude of
isospin-symmetry-breaking (ISB) corrections in both the nucleon and 4He. We
examine this issue in the present letter. Isospin admixtures in the nucleon are
determined in chiral perturbation theory, while those in 4He are derived from
nuclear interactions, including explicit ISB terms. A careful analysis of the
model dependence in the resulting predictions for the nucleon and nuclear ISB
contributions to the asymmetry is carried out. We conclude that, at the low
momentum transfers of interest in recent measurements reported by the HAPPEX
collaboration at Jefferson Lab, these contributions are of comparable magnitude
to those associated with strangeness components in the nucleon electric form
factor.Comment: 4 pages, 2 figures, revtex
Parametrization of Realistic Bethe-Salpeter Amplitude for the Deuteron
The parametrization of the realistic Bethe-Salpeter amplitude for the
deuteron is given. Eight components of the amplitude in the Euclidean space are
presented as an analytical fit to the numerical solution of the Bethe-Salpeter
equation in the ladder approximation. An applicability of the parametrization
to the observables of the deuteron is briefly discussed.Comment: LaTeX, 11 pages, 2 Postscript figures; Text of the Fortran program is
available from the author by reques
Efficient and realistic device modeling from atomic detail to the nanoscale
As semiconductor devices scale to new dimensions, the materials and designs
become more dependent on atomic details. NEMO5 is a nanoelectronics modeling
package designed for comprehending the critical multi-scale, multi-physics
phenomena through efficient computational approaches and quantitatively
modeling new generations of nanoelectronic devices as well as predicting novel
device architectures and phenomena. This article seeks to provide updates on
the current status of the tool and new functionality, including advances in
quantum transport simulations and with materials such as metals, topological
insulators, and piezoelectrics.Comment: 10 pages, 12 figure
Диагностика частотной области изоляции трансформатора
The first part of paper deals with the base information about diagnostics of power transformers. In this part are presented differently insulating methods, for example method of recovery voltage method, method of polarization and depolarization currents and chromatographic analysis. The second part of paper deals use of method of frequency domain spectroscopy for oil power transformers. This method is used in analysis insulating condition of power transformer with system of oil-paper. It was found, that the results of these tests are highly impacted by the operating temperature during the experimental measurement. Moisture and conductivity between insulating paper and oil in an insulating system are highly dependent from temperature. In the other part, the paper presents experimental results of the frequency diagnostic measurement for a real single-phase traction transformer 110/27 kV at different operating temperatures and states (with oil and without). Finally in the last part, the paper presents comparing frequency insulating measurements among several the same single-phase transformers 110/27 kV
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