2,870 research outputs found
No-Core shell model for A = 47 and A = 49
We apply an {\it ab-initio} approach to the nuclear structure of odd-mass
nuclei straddling . Starting with the NN interaction, that fits
two-body scattering and bound state data we evaluate the nuclear properties of
and nuclei in a no-core approach. Due to model space
limitations and the absence of 3-body interactions, we incorporate
phenomenological terms determined by fits to nuclei in a previous
effort. Our modified Hamiltonian produces reasonable spectra for these odd mass
nuclei. In addition to the differences in single-particle basis states, the
absence of a single-particle Hamiltonian in our no-core approach obscures
direct comparisons with valence effective NN interactions. Nevertheless, we
compare the fp-shell matrix elements of our initial and modified Hamiltonians
in the harmonic oscillator basis with a recent model fp-shell interaction, the
GXPF1 interaction of Honma, Otsuka, Brown and Mizusaki. Notable differences
emerge from these comparisons. In particular, our diagonal two-body
matrix elements are, on average, about 800-900keV more attractive. Furthermore,
while our initial and modified NN Hamiltonian fp-shell matrix elements are
strongly correlated, there is much less correlation with the GXPF1 matrix
elements.Comment: 17 pages including 14 figure
Model Order Selection Rules For Covariance Structure Classification
The adaptive classification of the interference covariance matrix structure
for radar signal processing applications is addressed in this paper. This
represents a key issue because many detection architectures are synthesized
assuming a specific covariance structure which may not necessarily coincide
with the actual one due to the joint action of the system and environment
uncertainties. The considered classification problem is cast in terms of a
multiple hypotheses test with some nested alternatives and the theory of Model
Order Selection (MOS) is exploited to devise suitable decision rules. Several
MOS techniques, such as the Akaike, Takeuchi, and Bayesian information criteria
are adopted and the corresponding merits and drawbacks are discussed. At the
analysis stage, illustrating examples for the probability of correct model
selection are presented showing the effectiveness of the proposed rules
Pion mass effects on axion emission from neutron stars through NN bremsstrahlung processes
The rates of axion emission by nucleon-nucleon bremsstrahlung are calculated
with the inclusion of the full momentum contribution from a nuclear one pion
exchange (OPE) potential. The contributions of the neutron-neutron (nn),
proton-proton (pp) and neutron-proton (np) processes in both the nondegenerate
and degenerate limits are explicitly given. We find that the finite momentum
corrections to the emissivities are quantitatively significant for the
non-degenerate regime and temperature-dependent, and should affect the existing
axion mass bounds. The trend of these nuclear effects is to diminish the
emissivities
Comment on 4D Lorentz invariance violations in the brane-world
The brane-world scenario offers the possibility for signals to travel outside
our visible universe and reenter it. We find the condition for a signal emitted
from the brane to return to the brane. We study the propagation of such signals
and show that, as seen by a 4D observer, these signals arrive earlier than
light traveling along the brane. We also study the horizon problem and find
that, while the bulk signals can travel far enough to homogenize the visible
universe, it is unlikely that they have a significant effect since they are
redshifted in the gravitational field of the bulk black hole.Comment: 21 pages, 6 figures, REVTEX, New section adde
Kaluza-Klein relics from warped reheating
It has been suggested that after brane-antibrane inflation in a
Klebanov-Strassler (KS) warped throat, metastable Kaluza-Klein (KK) excitations
can be formed due to nearly-conserved angular momenta along isometric
directions in the throat. If sufficiently long-lived, these relics could
conflict with big bang nucleosynthesis or baryogenesis by dominating the energy
density of the universe. We make a detailed estimate of the decay rate of such
relics using the low energy effective action of type IIB string theory
compactified on the throat geometry, with attention to powers of the warp
factor. We find that it is necessary to turn on SUSY-breaking deformations of
the KS background in order to ensure that the most dangerous relics will decay
fast enough. The decay rate is found to be much larger than the naive guess
based on the dimension of the operators which break the angular isometries of
the throat. For an inflationary warp factor of order , we obtain
the bound M_{3/2} \gsim 10^9 GeV on the scale of SUSY breaking to avoid
cosmological problems from the relics, which is satisfied in the KKLT
construction assumed to stabilize the compactification. Given the requirement
that the relics decay before nucleosynthesis or baryogenesis, we place bounds
on the mass of the relic as a function of the warp factor in the throat for
more general warped backgrounds.Comment: 30 pages, 7 figures. Added analysis and discussions to address the
referees concerns: explored the effects of different IR boundary conditions,
clarified the role of the simplified toy model, discussed the dominant
SUSY-preserving decay route (but still conclude the SUSY-breaking one is
faster). All original conclusions still hol
Lambda hyperonic effect on the normal driplines
A generalized mass formula is used to calculate the neutron and proton drip
lines of normal and lambda hypernuclei treating non-strange and strange nuclei
on the same footing. Calculations suggest existence of several bound
hypernuclei whose normal cores are unbound. Addition of Lambda or,
Lambda-Lambda hyperon(s) to a normal nucleus is found to cause shifts of the
neutron and proton driplines from their conventional limits.Comment: 6 pages, 4 tables, 0 figur
Microbiota signatures in type-2 diabetic patients with chronic kidney disease - A Pilot Study
The human microbiota is paramount for normal host physiology. Altered host-microbiome interactions are part of the pathogenesis of numerous common ailments. Currently, much emphasis is placed on the involvement of the microbiome in the pathogenesis of type-2 diabetes mellitus (T2DM), impaired glucose tolerance, and other metabolic disorders (i.e. obesity). Several studies found highly significant correlations of specific intestinal bacteria with T2DM. A better understanding of the role of the microbiome in diabetes and its complications might provide new insights in the development of new therapeutic principles.
Our pilot study investigates the microbiota patterns in Romanian type-2 diabetic patients with diabetic kidney disease. Fecal samples were collected from type 2-diabetic patients and healthy controls and further used for bacterial DNA isolation. Using 16 rDNA qRT-PCR, we analyzed phyla abundance (Bacteroidetes, Firmicutes) as well as the relative abundance of specific bacterial groups (Lactobacillus sp., Enterobacteriaceae, Ruminococus sp., Prevotella sp., Faecalibacterium sp., Clostridium coccoides, Clostridium leptum). Our study also investigates the diabetic fungal microbiome for the first time. Furthermore, we report significant correlations between the treatment regimen and microbiota composition in diabetic nephropathy
The relationship between innovation, knowledge, and performance in family and non-family firms: An analysis of SMEs
This study seeks to examine the relationship between innovation and knowledge in family versus non-family businesses with regard to performance. Data from 430 small and medium-sized enterprises were analyzed through hierarchical regression analysis, and innovation was found to be a significant factor in both family and non-family samples. However, knowledge in family firms was also found to be significant with innovation. Implications for theory and practice are discussed that may provide possible competitive advantage for small family firms
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