331 research outputs found
Quasiparticle interaction in nuclear matter with chiral three-nucleon forces
We derive the effective interaction between two quasiparticles in symmetric
nuclear matter resulting from the leading-order chiral three-nucleon force. We
restrict our study to the L=0,1 Landau parameters of the central quasiparticle
interaction computed to first order. We find that the three-nucleon force
provides substantial repulsion in the isotropic spin- and isospin-independent
component F_0 of the interaction. This repulsion acts to stabilize nuclear
matter against isoscalar density oscillations, a feature which is absent in
calculations employing low-momentum two-nucleon interactions only. We find a
rather large uncertainty for the nuclear compression modulus due to a sensitive
dependence on the low-energy constant c_3. The effective nucleon mass on the
Fermi surface, as well as the nuclear symmetry energy, receive only small
corrections from the leading-order chiral three-body force. Both the anomalous
orbital g-factor and the Landau-Migdal parameter g'_{NN} (characterizing the
spin-isospin response of nuclear matter) decrease with the addition of
three-nucleon correlations. In fact, the anomalous orbital g-factor remains
significantly smaller than its value extracted from experimental data, whereas
g'_{NN} still compares well with empirical values. The inclusion of the
three-nucleon force results in relatively small p-wave (L=1) components of the
central quasiparticle interaction, thus suggesting an effective interaction of
short range.Comment: 20 pages, 6 figure
Critical evaluation of the role of acarbose in the treatment of diabetes: patient considerations
Homocysteine in dogs with systemic inflammatory response syndrome
OBJECTIVES - To compare serum concentrations of homocysteine (Hcy) in dogs fitting
the criteria for the systemic inflammatory response syndrome (SIRS) and healthy dogs,
and compare these values to commonly measured B-vitamins.
METHODS – Study dogs were classified into noninfectious SIRS or sepsis groups and
blood was drawn on Day 1 of the patient’s hospitalization for the measurement of Hcy,
folate and cobalamin concentrations. Hcy was measured in 51 clinically normal dogs to
serve as the control group.
RESULTS - A statistically significant difference was found between the Hcy
concentrations of the healthy group when compared to noninfectious SIRS and sepsis
groups. Hcy values were not correlated with folate, cobalamin or APPLEfast severity
scores. Hcy concentrations were significantly lower in sick dogs when compared to the
control group, which is dissimilar to the human population.
CLINICAL SIGNIFCANCE - The clinical significance of Hcy changes in critically ill dogs is
currently unknown.http://aac.asm.orghb2014ab201
Small-scale solar magnetic fields
As we resolve ever smaller structures in the solar atmosphere, it has become
clear that magnetism is an important component of those small structures.
Small-scale magnetism holds the key to many poorly understood facets of solar
magnetism on all scales, such as the existence of a local dynamo, chromospheric
heating, and flux emergence, to name a few. Here, we review our knowledge of
small-scale photospheric fields, with particular emphasis on quiet-sun field,
and discuss the implications of several results obtained recently using new
instruments, as well as future prospects in this field of research.Comment: 43 pages, 18 figure
Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA
An investigation of the hadronic final state in diffractive and
non--diffractive deep--inelastic electron--proton scattering at HERA is
presented, where diffractive data are selected experimentally by demanding a
large gap in pseudo --rapidity around the proton remnant direction. The
transverse energy flow in the hadronic final state is evaluated using a set of
estimators which quantify topological properties. Using available Monte Carlo
QCD calculations, it is demonstrated that the final state in diffractive DIS
exhibits the features expected if the interaction is interpreted as the
scattering of an electron off a current quark with associated effects of
perturbative QCD. A model in which deep--inelastic diffraction is taken to be
the exchange of a pomeron with partonic structure is found to reproduce the
measurements well. Models for deep--inelastic scattering, in which a
sizeable diffractive contribution is present because of non--perturbative
effects in the production of the hadronic final state, reproduce the general
tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil
A Search for Selectrons and Squarks at HERA
Data from electron-proton collisions at a center-of-mass energy of 300 GeV
are used for a search for selectrons and squarks within the framework of the
minimal supersymmetric model. The decays of selectrons and squarks into the
lightest supersymmetric particle lead to final states with an electron and
hadrons accompanied by large missing energy and transverse momentum. No signal
is found and new bounds on the existence of these particles are derived. At 95%
confidence level the excluded region extends to 65 GeV for selectron and squark
masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure
Color superconducting quark matter core in the third family of compact stars
We investigate first order phase transitions from -equilibrated
hadronic matter to color flavor locked quark matter in compact star interior.
The hadronic phase including hyperons and Bose-Einstein condensate of
mesons is described by the relativistic field theoretical model with density
dependent meson-baryon couplings. The early appearance of hyperons and/or
Bose-Einstein condensate of mesons delays the onset of phase transition
to higher density. In the presence of hyperons and/or condensate, the
overall equations of state become softer resulting in smaller maximum masses
than the cases without hyperons and condensate. We find that the maximum
mass neutron stars may contain a mixed phase core of hyperons, condensate
and color superconducting quark matter. Depending on the parameter space, we
also observe that there is a stable branch of superdense stars called the third
family branch beyond the neutron star branch. Compact stars in the third family
branch may contain pure color superconducting core and have radii smaller than
those of the neutron star branch. Our results are compared with the recent
observations on RX J185635-3754 and the recently measured mass-radius
relationship by X-ray Multi Mirror-Newton Observatory.Comment: 24 pages, RevTex, 9 figures included; section II shortened, section
III elaborated, two new curves in Fig. 9 and acknowledgements added; version
to bepublished in Phys. Rev.
The KGP Model of Agency for Global Computing: Computational Model and Prototype Implementation
O uso do caranguejo maria-farinha Ocypode quadrata (Fabricius) (Crustacea, Ocypodidae) como indicador de impactos antropogênicos em praias arenosas da Ilha de Santa Catarina, Santa Catarina, Brasil
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