The orbifold cohomology of moduli of genus 3 curves

In this work we study the additive orbifold cohomology of the moduli stack of smooth genus g curves. We show that this problem reduces to investigating the rational cohomology of moduli spaces of cyclic covers of curves where the genus of the covering curve is g. Then we work out the case of genus g=3. Furthermore, we determine the part of the orbifold cohomology of the Deligne-Mumford compactification of the moduli space of genus 3 curves that comes from the Zariski closure of the inertia stack of M_3.Comment: 29 pages, 2 figures. Minor changes, to appear in Manuscripta Mat

Two-dimensional multivariate parametric models for radar applications-Part I: Maximum-entropy extensions for Toeplitz-block matrices

Copyright © 2008 IEEEIn a series of two papers, a new class of parametric models for two-dimensional multivariate (matrix-valued, space-time) adaptive processing is introduced. This class is based on the maximum-entropy extension and/or completion of partially specified matrix-valued Hermitian covariance matrices in both the space and time dimensions. This first paper considers the more restricted class of Toeplitz Hermitian covariance matrices that model stationary clutter. If the clutter is stationary only in time then we deal with a Toeplitz-block matrix, whereas clutter that is stationary in time and space is described by a Toeplitz-block-Toeplitz matrix. We first derive exact expressions for this new class of 2-D models that act as approximations for the unknown true covariance matrix. Second, we propose suboptimal (but computationally simpler) relaxed 2-D time-varying autoregressive models (ldquorelaxationsrdquo) that directly use the non-Toeplitz Hermitian sample covariance matrix. The high efficiency of these parametric models is illustrated by simulation results using true ground-clutter covariance matrices provided by the DARPA KASSPER Dataset 1, which is a trusted phenomenological airborne radar model, and a complementary AFRL dataset.Yuri I. Abramovich, Ben A. Johnson, and Nicholas K. Spence

Three-body structure of low-lying 12Be states

We investigate to what extent a description of 12Be as a three-body system made of an inert 10Be-core and two neutrons is able to reproduce the experimental 12Be data. Three-body wave functions are obtained with the hyperspherical adiabatic expansion method. We study the discrete spectrum of 12Be, the structure of the different states, the predominant transition strengths, and the continuum energy spectrum after high energy fragmentation on a light target. Two 0+, one 2+, one 1- and one 0- bound states are found where the first four are known experimentally whereas the 0- is predicted as an isomeric state. An effective neutron charge, reproducing the measured B(E1) transition and the charge rms radius in 11Be, leads to a computed B(E1) transition strength for 12Be in agreement with the experimental value. For the E0 and E2 transitions the contributions from core excitations could be more significant. The experimental 10Be-neutron continuum energy spectrum is also well reproduced except in the energy region corresponding to the 3/2- resonance in 11Be where core excitations contribute.Comment: 16 pages, 9 figures. Accepted for publication in Physical Review

Uninterruptible power supply system for mining industry enterprises

Immediate problem of compensating falls and deviations of voltage in the power supply systems of mining enterprises in order to ensure the proper level of power supply reliability for the most important technological consumers is substantiated in the article. The main causes of the voltage falls and deviations occurrence in the power supply systems of mining enterprises have been identified. The degree of different nature voltage falls and deviations influence on the dynamic and static stability of power supply systems is established. The necessity of ensuring an uninterrupted and guaranteed power supply mode for continuous technological processes of mining production is shown. The analysis of the existing regulatory documentation in the field of guaranteed and uninterrupted power supply is carried out. Based on the results of experimental studies and mathematical modeling, a relationship has been revealed between formally independent sources of electricity supply from the viewpoint of existing regulatory documentation. The expression allowing determination of cohesion coefficient of two power supply sources is given. The necessity of taking into account the degree of sources interconnection in the synthesis of uninterruptible power supply systems for mining enterprises is justified. The analysis of existing technical means and solutions for reserving power supply for mining enterprises, including modern uninterruptible online power supply systems, own needs power plants, as well as dynamic voltage distortion compensators, is done. The classification of the consumers categories related to possibility of their complete or partial shutdown in emergency modes in case of voltage falls and interruptions is given. System of uninterruptible power supply for mining enterprises based on the combined use of alternative and renewable energy sources, uninterruptible power supply sources and a multi-step automatic reserve transition system, which allows ensuring uninterrupted mode of energy supply for the most responsible consumers of mining enterprises, was developed

New broad 8Be nuclear resonances

Energies, total and partial widths, and reduced width amplitudes of 8Be resonances up to an excitation energy of 26 MeV are extracted from a coupled channel analysis of experimental data. The presence of an extremely broad J^pi = 2^+ ``intruder'' resonance is confirmed, while a new 1^+ and very broad 4^+ resonance are discovered. A previously known 22 MeV 2^+ resonance is likely resolved into two resonances. The experimental J^pi T = 3^(+)? resonance at 22 MeV is determined to be 3^-0, and the experimental 1^-? (at 19 MeV) and 4^-? resonances to be isospin 0.Comment: 16 pages, LaTe

Persistent currents of noninteracting electrons

We thoroughly study the persistent current of noninteracting electrons in one, two, and three dimensional thin rings. We find that the results for noninteracting electrons are more relevant for individual mesoscopic rings than hitherto appreciated. The current is averaged over all configurations of the disorder, whose amount is varied from zero up to the diffusive limit, keeping the product of the Fermi wave number and the ring's circumference constant. Results are given as functions of disorder and aspect ratios of the ring. The magnitude of the disorder-averaged current may be larger than the root-mean-square fluctuations of the current from sample to sample even when the mean free path is smaller, but not too small, than the circumference of the ring. Then a measurement of the persistent current of a typical sample will be dominated by the magnitude of the disorder averaged current.Comment: 10 pages, 4 figure

Threshold Effects in Multi-channel Coupling and Spectroscopic Factors in Exotic Nuclei

In the threshold region, the cross section and the associated overlap integral obey the Wigner threshold law that results in the Wigner-cusp phenomenon. Due to flux conservation, a cusp anomaly in one channel manifests itself in other open channels, even if their respective thresholds appear at a different energy. The shape of a threshold cusp depends on the orbital angular momentum of a scattered particle; hence, studies of Wigner anomalies in weakly bound nuclei with several low-lying thresholds can provide valuable spectroscopic information. In this work, we investigate the threshold behavior of spectroscopic factors in neutron-rich drip-line nuclei using the Gamow Shell Model, which takes into account many-body correlations and the continuum effects. The presence of threshold anomalies is demonstrated and the implications for spectroscopic factors are discussed.Comment: Accepted in Physical Review C Figure correcte

Statistical Diagnostics of Metastatic Involvement of Regional Lymph Nodes

The method of statistical classification with indicating patients that require more detailed diagnostics is proposed and analysed