Torus orbits on homogeneous varieties and Kac polynomials of quivers

In this paper we prove that the counting polynomials of certain torus orbits in products of partial flag varieties coincides with the Kac polynomials of supernova quivers, which arise in the study of the moduli spaces of certain irregular meromorphic connections on trivial bundles over the projective line. We also prove that these polynomials can be expressed as a specialization of Tutte polynomials of certain graphs providing a combinatorial proof of the non-negativity of their coefficients

Alien Registration- Letellier, Paul E. (Biddeford, York County)

https://digitalmaine.com/alien_docs/4796/thumbnail.jp

Peeling Bifurcations of Toroidal Chaotic Attractors

Chaotic attractors with toroidal topology (van der Pol attractor) have counterparts with symmetry that exhibit unfamiliar phenomena. We investigate double covers of toroidal attractors, discuss changes in their morphology under correlated peeling bifurcations, describe their topological structures and the changes undergone as a symmetry axis crosses the original attractor, and indicate how the symbol name of a trajectory in the original lifts to one in the cover. Covering orbits are described using a powerful synthesis of kneading theory with refinements of the circle map. These methods are applied to a simple version of the van der Pol oscillator.Comment: 7 pages, 14 figures, accepted to Physical Review

Arithmetic harmonic analysis on character and quiver varieties

We present a conjecture generalizing the Cauchy formula for Macdonald polynomials. This conjecture encodes the mixed Hodge polynomials of the character varieties of representations of the fundamental group of a Riemann surface of genus g to GL_n(C) with fixed generic semi-simple conjugacy classes at k punctures. Using the character table of GL_n(F_q) we calculate the E-polynomial of these character varieties and confirm that it is as predicted by our main conjecture. Then, using the character table of gl_n(F_q), we calculate the E-polynomial of certain associated comet-shaped quiver varieties, the additive analogues of our character variety, and find that it is the pure part of our conjectured mixed Hodge polynomial. Finally, we observe that the pure part of our conjectured mixed Hodge polynomial also equals certain multiplicities in the tensor product of irreducible representations of GL_n(F_q). This implies a curious connection between the representation theory of GL_n(F_q) and Kac-Moody algebras associated with comet-shaped, typically wild, quivers.Comment: To appear in Duke Math. Journal + a section with examples is adde

Topology of character varieties and representations of quivers

In arXiv:0810.2076 we presented a conjecture generalizing the Cauchy formula for Macdonald polynomials. This conjecture encodes the mixed Hodge polynomials of the representation varieties of Riemann surfaces with semi-simple conjugacy classes at the punctures. We proved several results which support this conjecture. Here we announce new results which are consequences of those of arXiv:0810.2076

Protection of pigs against experimental Salmonella Typhimurium infection by use of a single dose subunit slow delivery vaccine

Infections caused by septicemic strains of Salmonella are significant animal health as well as food safety concerns for the North American swine industry. Among the various strategies to control these infections at the herd level, development of vaccines are attractive alternatives. In this study, based on previous studies of immune response to various protems following natural and experimental infections of pigs by Salmonella, we designed a subunit slow delivery vaccine and tested it in an experimental model of infection. The selected immunogenic protein was cloned and purified by chromatography. The purified protein was then incorporated m PLGA (a polymer that is slowly degraded within the animal\u27s gastro-intestinal system) microspheres and given orally once to groups of pigs (n=8) while control animals (n=8) received only PBS. Animals were challenged orally 4 weeks after the vaccmation with 108 cells of a virulent strains of Salmonella Typhimurium. Animals were examined twice a day and climcal signs evaluated using a predetermined scoring grid. Pigs were sacrificed 12 days later and bacterial cultures of vanous organs, electron microscopy and evaluation of lgA response by ELISA were performed. No significant difference was found at bacteriology and ELISA but marked differences in clinical signs were observed between vaccinated and non vaccinated animals. None of vaccmated animals showed fever exceeding 40°C while it was observed in 5 out of 8 non vaccinated Only one of vaccmated pigs showed mild diarrhea while severe diarrhea was observed in all control animals different sizes of microspheres were observed in intestinal crypts of vaccinated animals at electron microscopy. We concluded that this vaccine can protect pigs against clinical signs associated with experimental infection by Salmonella Typhimunum

Impact of use of Tylosin and Virginiamycin on antimicrobial agents resistance profiles of Enterococcus spp. and E. coli isolates from swine in field conditions

Enterococcus spp. and E. coli are recognized as indicator microorganisms for the human and animal intestinal flora, and are also known to be potential reservoirs of antimicrobial resistance genes. Among the various use of antimicrobial agents that can promote antibioresistance, on farm use of growth promoters raises public health concerns. The aim of this study was to evaluate the impact of the use of selected growth promoters on antimicrobial resistance profiles of Enterococcus spp. and E. coli isolates from swine in field conditions. Enterococcus and E. coli isolates obtained from pooled fecal samples of pigs receiving Tylosin (44 ppm, n = 100) and Virginiamycin (22 ppm, n=1 00) were compared to isolates obtained from a control group (n = 1 00) fed without growth promoters, in field conditions. Comparison was done between isolates obtatned in the first week of treatment and isolates obtained 1n the 15th week

Assessing observability of chaotic systems using Delay Differential Analysis

Observability can determine which recorded variables of a given system are optimal for discriminating its different states. Quantifying observability requires knowledge of the equations governing the dynamics. These equations are often unknown when experimental data are considered. Consequently, we propose an approach for numerically assessing observability using Delay Differential Analysis (DDA). Given a time series, DDA uses a delay differential equation for approximating the measured data. The lower the least squares error between the predicted and recorded data, the higher the observability. We thus rank the variables of several chaotic systems according to their corresponding least square error to assess observability. The performance of our approach is evaluated by comparison with the ranking provided by the symbolic observability coefficients as well as with two other data-based approaches using reservoir computing and singular value decomposition of the reconstructed space. We investigate the robustness of our approach against noise contamination.Comment: 14 pages, 3 figures, 5 table

Nonlinear Analysis of Irregular Variables

The Fourier spectral techniques that are common in Astronomy for analyzing periodic or multi-periodic light-curves lose their usefulness when they are applied to unsteady light-curves. We review some of the novel techniques that have been developed for analyzing irregular stellar light or radial velocity variations, and we describe what useful physical and astronomical information can be gained from their use.Comment: 31 pages, to appear as a chapter in `Nonlinear Stellar Pulsation' in the Astrophysics and Space Science Library (ASSL), Editors: M. Takeuti & D. Sasselo

Risk factors associated with the presence of Salmonella in swine herds in Quebec

Based on the generic HACCP plan for swine production developed by the Canadian Pork Council, Agriculture and Agrifood Canada and provincial authorities, a questionnaire was developed to evaluate the relationship between the application of good production practices and the presence of Salmonella in swine herds. Seventy eight finishing units were sampled (n=l5) at 2 different occasions to detect the presence of Salmonella in fecal material and in the environment. Each producer was asked to answer 20 questions and their answers were validated by a veterinarian during the herd sampling. Salmonella was found in 16 out of 28 herds. Logistic regression analysis revealed that the use of multiple sources for the purchase of incoming animals was correlated with the presence of salmonella in herds. Reduction of the number of sources for incoming animals should thus be considered in order to reduce the risk of acquiring Salmonella in swine herds