8,986 research outputs found
Domain Walls in AdS-Einstein-scalar Gravity
In this note, we will show that the supergravity theory which is dual to ABJM
field theory can be consistently reduced to scalar-coupled AdS-Einstein gravity
and then consider the reflection symmetric domain wall and its small
fluctuation. This domain wall solution is none other than dimensional reduction
of M2-brane configuration.Comment: 14 pages, v2: minor change
Quarkonium states in an anisotropic QCD plasma
We consider quarkonium in a hot QCD plasma which, due to expansion and
non-zero viscosity, exhibits a local anisotropy in momentum space. At short
distances the heavy-quark potential is known at tree level from the
hard-thermal loop resummed gluon propagator in anisotropic perturbative QCD.
The potential at long distances is modeled as a QCD string which is screened at
the same scale as the Coulomb field. At asymptotic separation the potential
energy is non-zero and inversely proportional to the temperature. We obtain
numerical solutions of the three-dimensional Schroedinger equation for this
potential. We find that quarkonium binding is stronger at non-vanishing
viscosity and expansion rate, and that the anisotropy leads to polarization of
the P-wave states.Comment: 18 pages, 6 figures, final version, to appear in PR
Determinants of neonatal mortality in rural and urban Nigeria: Evidence from a population-based national survey
Background
Significant reduction in the global burden of neonatal mortality was achieved through the millennium development goals. In Nigeria, however, only a marginal reduction was realized. This study assesses the ruralâurban differences in neonatal mortality rate (NMR) and the associated risk factors in Nigeria.
Methods
The dataset from the 2013 Nigeria demographic and health survey (NDHS), disaggregated by ruralâurban residence (n = 20 449 and 9935, respectively), was explored using univariate, bivariate, and multivariable analysis. Complex samples analysis was applied to adjust for the unequal selection probabilities due to the multi-stage cluster sampling method used in the 2013 NDHS. The adjusted relationship between the outcome and predictor variables was assessed on multi-level logistic regression analysis.
Results
NMR for rural and urban populations was 36 and 28 deaths per 1000 live births, respectively. Risk factors in urban residence were lack of electricity access (adjusted OR [AOR], 1.555; 95%CI: 1.089â2.220), small birth size (as a proxy for low birthweight; AOR, 3.048; 95%CI: 2.047â4.537), and male gender (AOR, 1.666; 95%CI: 1.215â2.284). Risk factors in rural residence were small birth size (a proxy for low birthweight; AOR, 2.118; 95%CI: 1.600â2.804), and birth interval \u3c 2 years (AOR, 2.149; 95%CI: 1.760â2.624). Cesarean delivery was a risk factor both in rural (AOR, 5.038; 95%CI: 2.617â9.700) and urban Nigeria (AOR, 2.632; 95%CI: 1.543â4.489).
Conclusions
Determinants of neonatal mortality were different in rural and urban Nigeria, and rural neonates had greater risk of mortality than their urban counterparts
Local Algorithms for Block Models with Side Information
There has been a recent interest in understanding the power of local
algorithms for optimization and inference problems on sparse graphs. Gamarnik
and Sudan (2014) showed that local algorithms are weaker than global algorithms
for finding large independent sets in sparse random regular graphs. Montanari
(2015) showed that local algorithms are suboptimal for finding a community with
high connectivity in the sparse Erd\H{o}s-R\'enyi random graphs. For the
symmetric planted partition problem (also named community detection for the
block models) on sparse graphs, a simple observation is that local algorithms
cannot have non-trivial performance.
In this work we consider the effect of side information on local algorithms
for community detection under the binary symmetric stochastic block model. In
the block model with side information each of the vertices is labeled
or independently and uniformly at random; each pair of vertices is
connected independently with probability if both of them have the same
label or otherwise. The goal is to estimate the underlying vertex
labeling given 1) the graph structure and 2) side information in the form of a
vertex labeling positively correlated with the true one. Assuming that the
ratio between in and out degree is and the average degree , we characterize three different regimes under which a
local algorithm, namely, belief propagation run on the local neighborhoods,
maximizes the expected fraction of vertices labeled correctly. Thus, in
contrast to the case of symmetric block models without side information, we
show that local algorithms can achieve optimal performance for the block model
with side information.Comment: Due to the limitation "The abstract field cannot be longer than 1,920
characters", the abstract here is shorter than that in the PDF fil
Wavelength-swept Tm-doped fiber laser operating in the two-micron wavelength band
A wavelength-swept thulium-doped silica fiber laser using an intracavity rotating slotted-disk wavelength scanning filter in combination with an intracavity solid etalon for passive control of temporal and spectral profiles is reported. The laser yielded a wavelength swept output in a step-wise fashion with each laser pulse separated from the previous pulse by a frequency interval equal to the free-spectral-range of the etalon and with an instantaneous linewidth of <0.05 nm. Scanning ranges from 1905 nm to 2049 nm for a cladding-pumping laser configuration, and from 1768 nm to 1956 nm for a core-pumping laser configuration were achieved at average output powers up to ~1 W
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