408 research outputs found
Blow-up solutions for linear perturbations of the Yamabe equation
For a smooth, compact Riemannian manifold (M,g) of dimension N \geg 3, we
are interested in the critical equation where \Delta_g is the Laplace--Beltrami
operator, S_g is the Scalar curvature of (M,g), , and
is a small parameter
Influence of the halo upon angular distributions for elastic scattering and breakup
The angular distributions for elastic scattering and breakup of halo nuclei
are analysed using a near-side/far-side decomposition within the framework of
the dynamical eikonal approximation. This analysis is performed for 11Be
impinging on Pb at 69 MeV/nucleon. These distributions exhibit very similar
features. In particular they are both near-side dominated, as expected from
Coulomb-dominated reactions. The general shape of these distributions is
sensitive mostly to the projectile-target interactions, but is also affected by
the extension of the halo. This suggests the elastic scattering not to be
affected by a loss of flux towards the breakup channel.Comment: 11 pages, 3 figures, accepted for publication in Phys. Lett.
Four-body effects on 9Be + 208Pb scattering and fusion around the Coulomb barrier
We investigate the 9Be + 208Pb elastic scattering and fusion at energies
around the Coulomb barrier. The Be nucleus is described in a \alpha +
\alpha + n three-body model, using the hyperspherical coordinate method. The
scattering with Pb is then studied with the Continuum Discretized
Coupled Channel (CDCC) method, where the \alpha + \alpha + n continuum is
approximated by a discrete number of pseudostates. Optical potentials for the
Pb and Pb systems are taken from the literature. We
present elastic-scattering and fusion cross sections at different energies, and
investigate the convergence with respect to the truncation of the \alpha +
\alpha + n continuum. A good agreement with experiment is obtained, considering
that there is no parameter fitting. We show that continuum effects increase at
low energies.Comment: 6 pages, 4 figures. Submitted to the proceedings of the "NUBA
Conference Series -1: Nuclear Physics and Astrophysics" Adrasan-Antalya,
Turkey, September 15-21, 201
Nonlinear Klein-Gordon-Maxwell systems with Neumann boundary conditions on a Riemannian manifold with boundary
Let (M,g) be a smooth compact, n dimensional Riemannian manifold, n=3,4 with
smooth n-1 dimensional boundary. We search the positive solutions of the
singularly perturbed Klein Gordon Maxwell Proca system with homogeneous Neumann
boundary conditions or for the singularly perturbed Klein Gordon Maxwell system
with mixed Dirichlet Neumann homogeneous boundary conditions. We prove that
stable critical points of the mean curvature of the boundary generates
solutions when the perturbation parameter is sufficiently small.Comment: arXiv admin note: text overlap with arXiv:1410.884
Sharp constants in weighted trace inequalities on Riemannian manifolds
We establish some sharp weighted trace inequalities
W^{1,2}(\rho^{1-2\sigma}, M)\hookrightarrow L^{\frac{2n}{n-2\sigma}}(\pa M)
on dimensional compact smooth manifolds with smooth boundaries, where
is a defining function of and . This is stimulated
by some recent work on fractional (conformal) Laplacians and related problems
in conformal geometry, and also motivated by a conjecture of Aubin.Comment: 34 page
Quantization for an elliptic equation of order 2m with critical exponential non-linearity
On a smoothly bounded domain we consider a sequence of
positive solutions in to
the equation subject to Dirichlet
boundary conditions, where . Assuming that
we
prove that is an integer multiple of
\Lambda_1:=(2m-1)!\vol(S^{2m}), the total -curvature of the standard
-dimensional sphere.Comment: 33 page
Use of partial least squares regression to impute SNP genotypes in Italian Cattle breeds
Background
The objective of the present study was to test the ability of the partial least squares regression technique to impute genotypes from low density single nucleotide polymorphisms (SNP) panels i.e. 3K or 7K to a high density panel with 50K SNP. No pedigree information was used.
Methods
Data consisted of 2093 Holstein, 749 Brown Swiss and 479 Simmental bulls genotyped with the Illumina 50K Beadchip. First, a single-breed approach was applied by using only data from Holstein animals. Then, to enlarge the training population, data from the three breeds were combined and a multi-breed analysis was performed. Accuracies of genotypes imputed using the partial least squares regression method were compared with those obtained by using the Beagle software. The impact of genotype imputation on breeding value prediction was evaluated for milk yield, fat content and protein content.
Results
In the single-breed approach, the accuracy of imputation using partial least squares regression was around 90 and 94% for the 3K and 7K platforms, respectively; corresponding accuracies obtained with Beagle were around 85% and 90%. Moreover, computing time required by the partial least squares regression method was on average around 10 times lower than computing time required by Beagle. Using the partial least squares regression method in the multi-breed resulted in lower imputation accuracies than using single-breed data. The impact of the SNP-genotype imputation on the accuracy of direct genomic breeding values was small. The correlation between estimates of genetic merit obtained by using imputed versus actual genotypes was around 0.96 for the 7K chip.
Conclusions
Results of the present work suggested that the partial least squares regression imputation method could be useful to impute SNP genotypes when pedigree information is not available
A compactness theorem for scalar-flat metrics on manifolds with boundary
Let (M,g) be a compact Riemannian manifold with boundary. This paper is
concerned with the set of scalar-flat metrics which are in the conformal class
of g and have the boundary as a constant mean curvature hypersurface. We prove
that this set is compact for dimensions greater than or equal to 7 under the
generic condition that the trace-free 2nd fundamental form of the boundary is
nonzero everywhere.Comment: 49 pages. Final version, to appear in Calc. Var. Partial Differential
Equation
New Gravity Map of the Western Galicia Margin:The Spanish Exclusive Economic Zone Project
Since 1995, the most intensive mapping of
the seafloor off the Spanish coast has been
carried out in the framework of the Spanish
Exclusive Economic Zone Project (ZEEE).The
main objectives of this project are to obtain
improved multibeam bathymetric cartography
of the areas off Spanish coastlines, and to perform
a geophysical survey,well-suited with a
10-knot navigation velocity (some techniques
requires lower navigation velocity).
The geophysical survey includes gravity, geomagnetism,
and low-penetration seismic techniques
in order to infer the geological structure
of the seafloor. Other oceanographic variables
such as current, surface salinity, and temperature
profiles, can be recorded without compromising
this systematic survey effort.
The ZEEE Project has carried out its survey
activities for one month every year.Data
acquisition is achieved aboard the Spanish
R/V Hesperides. Until 1997, surveying efforts
concentrated on the Balearic Sea and Valencia
Gulf, both in the western Mediterranean Sea.
Between 1998 and 2000, the ZEEE Project
investigations were conducted offshore the
Canary Archipelago. Since 2001, the third
phase of the program has been focused on
the West Galicia Margin in the northeastern
Atlantic Ocean.
Survey results on the West Galicia Margin area
are of interest for two key reasons. First, there
is great scientific interest in the improvement
of the knowledge of this non-volcanic rifting
margin, since this margin offers good conditions
for the study of the processes that take
place in this type of geological context,because
it is sediment-starved.
Second, the obtained results also have major
socioeconomic repercussions because they
can prove significant to defining the expansion
of the Spanish shelf,beyond Spainâs Economic
Exclusive Zone distance of 200 nautical miles.
All of the gravity data acquired to date on
this area have been stored as a database, with
the aim of preparing gravity anomaly maps
on a scale 1:200,000.The database and gravity
anomaly charts from the ZEEE Project will
provide the most coherent and complete gravity
perspective available for this area.
This article describes the efforts and accomplishments
of the project to date
A threshold phenomenon for embeddings of into Orlicz spaces
We consider a sequence of positive smooth critical points of the
Adams-Moser-Trudinger embedding of into Orlicz spaces. We study its
concentration-compactness behavior and show that if the sequence is not
precompact, then the liminf of the -norms of the functions is greater
than or equal to a positive geometric constant.Comment: 14 Page
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