28,765 research outputs found
The Dirichlet Problem for Curvature Equations in Riemannian Manifolds
We prove the existence of classical solutions to the Dirichlet problem for a
class of fully nonlinear elliptic equations of curvature type on Riemannian
manifolds. We also derive new second derivative boundary estimates which allows
us to extend some of the existence theorems of Caffarelli, Nirenberg and Spruck
[4] and Ivochkina, Trundinger and Lin [19] to more general curvature functions
and less convex domains.Comment: 32 pages, no figures. Final version. Paper accepted to publication in
Indiana University Mathematics Journa
STiC -- A multi-atom non-LTE PRD inversion code for full-Stokes solar observations
The inference of the underlying state of the plasma in the solar chromosphere
remains extremely challenging because of the nonlocal character of the observed
radiation and plasma conditions in this layer. Inversion methods allow us to
derive a model atmosphere that can reproduce the observed spectra by
undertaking several physical assumptions.
The most advanced approaches involve a depth-stratified model atmosphere
described by temperature, line-of-sight velocity, turbulent velocity, the three
components of the magnetic field vector, and gas and electron pressure. The
parameters of the radiative transfer equation are computed from a solid ground
of physical principles. To apply these techniques to spectral lines that sample
the chromosphere, NLTE effects must be included in the calculations.
We developed a new inversion code STiC to study spectral lines that sample
the upper chromosphere. The code is based the RH synthetis code, which we
modified to make the inversions faster and more stable. For the first time,
STiC facilitates the processing of lines from multiple atoms in non-LTE, also
including partial redistribution effects. Furthermore, we include a
regularization strategy that allows for model atmospheres with a complex
stratification, without introducing artifacts in the reconstructed physical
parameters, which are usually manifested in the form of oscillatory behavior.
This approach takes steps toward a node-less inversion, in which the value of
the physical parameters at each grid point can be considered a free parameter.
In this paper we discuss the implementation of the aforementioned techniques,
the description of the model atmosphere, and the optimizations that we applied
to the code. We carry out some numerical experiments to show the performance of
the code and the regularization techniques that we implemented. We made STiC
publicly available to the community.Comment: Accepted for publication in Astronomy & Astrophysic
Larval description and phylogenetic placement of the Australian endemic genus Barretthydrus Lea, 1927 (Coleoptera: Dytiscidae: Hydroporinae: Hydroporini: Sternopriscina)
The larvae of the Australian endemic species Barretthydrus tibialis Lea, 1927 and Barretthydrus geminatus Lea, 1927 are described and illustrated for the first time, with detailed morphometric and chaetotaxic analyses of the cephalic capsule, head appendages, legs, last abdominal segment, and urogomphi. A parsimony analysis based on 118 informative larval characteristics of 34 species in all 10 tribes of the subfamily Hydroporinae was conducted using the program TNT. No clear larval morphological synapomorphies support the monophyletic origin of the tribe Hydroporini. Compared to other known larvae of Hydroporini, Barretthydrus Lea is postulated to share a closer phylogenetic relationship with Antiporus Sharp, which reinforces their inclusion in the subtribe Sternopriscina.Fil: Alarie, Yves. Laurentian University. Department of Biology; CanadĂĄFil: Michat, Mariano Cruz. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y BiologĂa Experimental. Laboratorio de EntomologĂa; ArgentinaFil: Hendrich, L.. Zoologische Staatssammlung Munchen; AlemaniaFil: Watts, Chris H. S.. South Australian Museum; Australi
The Luminosity Function of Low-Redshift Abell Galaxy Clusters
We present the results from a survey of 57 low-redshift Abell galaxy clusters
to study the radial dependence of the luminosity function (LF). The dynamical
radius of each cluster, r200, was estimated from the photometric measurement of
cluster richness, Bgc. The shape of the LFs are found to correlate with radius
such that the faint-end slope, alpha, is generally steeper on the cluster
outskirts. The sum of two Schechter functions provides a more adequate fit to
the composite LFs than a single Schechter function. LFs based on the selection
of red and blue galaxies are bimodal in appearance. The red LFs are generally
flat for -22 < M_Rc < -18, with a radius-dependent steepening of alpha for M_Rc
> -18. The blue LFs contain a larger contribution from faint galaxies than the
red LFs. The blue LFs have a rising faint-end component (alpha ~ -1.7) for M_Rc
> -21, with a weaker dependence on radius than the red LFs. The dispersion of
M* was determined to be 0.31 mag, which is comparable to the median measurement
uncertainty of 0.38 mag. This suggests that the bright-end of the LF is
universal in shape at the 0.3 mag level. We find that M* is not correlated with
cluster richness when using a common dynamical radius. Also, we find that M* is
weakly correlated with BM-type such that later BM-type clusters have a brighter
M*. A correlation between M* and radius was found for the red and blue galaxies
such that M* fades towards the cluster center.Comment: Accepted for publication in ApJ, 16 pages, 4 tables, 24 figure
Using pedestrian counts to assess community-wide interventions to increase physical activity in rural Cuba, New Mexico.
Presented at: Society for Advancement of Chicanos/Hispanics and Native Americans in Science; October 29-31, 2015; Washington, DC.https://digitalrepository.unm.edu/prc-posters-presentations/1048/thumbnail.jp
Instrumentation for hydrogen slush storage containers
Hydrogen liquid and slush tank continuous inventory during ground storag
Asymmetric distribution of primary cilia allocates satellite cells for self-renewal
Regeneration of vertebrate skeletal muscles requires satellite cells, a population of stem cells that are quiescent in normal conditions and
divide, differentiate, and self-renew upon activation triggered by exercise, injury, and degenerative diseases. Satellite cell self-renewal is
essential for long-term tissue homeostasis, and previous work has identified a number of external cues that control this process. However,
little is known of the possible intrinsic control mechanisms of satellite cell self-renewal. Here, we show that quiescent satellite cells harbor
a primary cilium, which is rapidly disassembled upon entry into the cell cycle. Contrasting with a commonly accepted belief, cilia reassembly
does not occur uniformly in cells exiting the cell cycle. We found that primary cilia reassemble preferentially in cells committed to
self-renew, and disruption of cilia reassembly causes a specific deficit in self-renewing satellite cells. These observations indicate that primary
cilia provide an intrinsic cue essential for satellite cell self-renewal
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