20,263 research outputs found
Status of Women and Girls in Southern Arizona 2010
With the publication of the Status of Women and Girls in Southern Arizona report in the spring of 2009, the Women's Foundation of Southern Arizona achieved one of its major goals of establishing a comprehensive and accessible resource to provide data and analysis documenting the lives of women and girls in our region. We are now very pleased to publish the first of what are intended to be annual updates to the original report. These yearly updates will allow us not only to present the most current data on women's education, health, employment and other topics, but also to track where change is needed and measure the impact we, and our partners, have in the community at arge
Recent developments in shock-capturing schemes
The development of the shock capturing methodology is reviewed, paying special attention to the increasing nonlinearity in its design and its relation to interpolation. It is well-known that higher-order approximations to a discontinuous function generate spurious oscillations near the discontinuity (Gibbs phenomenon). Unlike standard finite-difference methods which use a fixed stencil, modern shock capturing schemes use an adaptive stencil which is selected according to the local smoothness of the solution. Near discontinuities this technique automatically switches to one-sided approximations, thus avoiding the use of discontinuous data which brings about spurious oscillations
Group Symmetry and non-Gaussian Covariance Estimation
We consider robust covariance estimation with group symmetry constraints.
Non-Gaussian covariance estimation, e.g., Tyler scatter estimator and
Multivariate Generalized Gaussian distribution methods, usually involve
non-convex minimization problems. Recently, it was shown that the underlying
principle behind their success is an extended form of convexity over the
geodesics in the manifold of positive definite matrices. A modern approach to
improve estimation accuracy is to exploit prior knowledge via additional
constraints, e.g., restricting the attention to specific classes of covariances
which adhere to prior symmetry structures. In this paper, we prove that such
group symmetry constraints are also geodesically convex and can therefore be
incorporated into various non-Gaussian covariance estimators. Practical
examples of such sets include: circulant, persymmetric and complex/quaternion
proper structures. We provide a simple numerical technique for finding maximum
likelihood estimates under such constraints, and demonstrate their performance
advantage using synthetic experiments
Do Longer Delays Matter? The Effect of Prolonging Delay in CTL Activation
The activation of a specific immune response takes place in the lymphoid
organs such as the spleen. We present here a simplified model of the
proliferation of specific immune cells in the form of a single delay equation.
We show that the system can undergo switches in stability as the delay is
increased, and we interpret these results in the context of sustaining an
effective immune response to a dendritic cell vaccine.Comment: 7 pages, 5 figures. Presented at the 8th AIMS Conference on Dynamical
Systems, Differential Equations and Applications that took place in Dresden,
Germany, May 25-28, 201
Compressed matched filter for non-Gaussian noise
We consider estimation of a deterministic unknown parameter vector in a
linear model with non-Gaussian noise. In the Gaussian case, dimensionality
reduction via a linear matched filter provides a simple low dimensional
sufficient statistic which can be easily communicated and/or stored for future
inference. Such a statistic is usually unknown in the general non-Gaussian
case. Instead, we propose a hybrid matched filter coupled with a randomized
compressed sensing procedure, which together create a low dimensional
statistic. We also derive a complementary algorithm for robust reconstruction
given this statistic. Our recovery method is based on the fast iterative
shrinkage and thresholding algorithm which is used for outlier rejection given
the compressed data. We demonstrate the advantages of the proposed framework
using synthetic simulations
Convolution semigroups on locally compact quantum groups and noncommutative Dirichlet forms
The subject of this paper is the study of convolution semigroups of states on
a locally compact quantum group, generalising classical families of
distributions of a L\'{e}vy process on a locally compact group. In particular a
definitive one-to-one correspondence between symmetric convolution semigroups
of states and noncommutative Dirichlet forms satisfying the natural translation
invariance property is established, extending earlier partial results and
providing a powerful tool to analyse such semigroups. This is then applied to
provide new characterisations of the Haagerup Property and Property (T) for
locally compact quantum groups, and some examples are presented. The proofs of
the main theorems require developing certain general results concerning
Haagerup's -spaces.Comment: 52 pages. v2: minor changes. To appear in Journal de Math\'ematiques
Pures et Appliqu\'ee
Ergodic theory for quantum semigroups
Recent results of L. Zsido, based on his previous work with C. P. Niculescu
and A. Stroh, on actions of topological semigroups on von Neumann algebras,
give a Jacobs-de Leeuw-Glicksberg splitting theorem at the von Neumann algebra
(rather than Hilbert space) level. We generalize this to the framework of
actions of quantum semigroups, namely Hopf-von Neumann algebras. To this end,
we introduce and study a notion of almost periodic vectors and operators that
is suitable for our setting.Comment: 21 pages. v2: minor changes. To appear in the Journal of the London
Mathematical Societ
A cosmic superfluid phase
The universe may have undergone a superfluid-like phase during its evolution, resulting from the injection of nontopological charge into the spontaneously broken vacuum. In the presence of vortices this charge is identified with angular momentum. This leads to turbulent domains on the scale of the correlation length. By restoring the symmetry at low temperatures, the vortices dissociate and push the charges to the boundaries of these domains. The model can be scaled (phenomenologically) to very low energies, it can be incorporated in a late time phase transition and form large scale structure in the boundary layers of the correlation volumes. The novel feature of the model lies in the fact that the dark matter is endowed with coherent motion. The possibilities of identifying this flow around superfluid vortices with the observed large scale bulk motion is discussed. If this identification is possible, then the definite prediction can be made that a more extended map of peculiar velocities would have to reveal large scale circulations in the flow pattern
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