Poisson Structure Induced (Topological) Field Theories

A class of two dimensional field theories, based on (generically degenerate) Poisson structures and generalizing gravity-Yang-Mills systems, is presented. Locally, the solutions of the classical equations of motion are given. A general scheme for the quantization of the models in a Hamiltonian formulation is found.Comment: 6 pages, LaTeX, TUW940

Identification of human papillomavirus DNA in cutaneous lesions of Cowden syndrome

Background: Cowden syndrome (CS) or multiple hamartoma syndrome is a cancer-associated genodermatosis inherited in an autosomal dominant pattern. One of the diagnostic criteria is facial papules which are felt to be trichilemmomas, benign hair follicle tumors, which some consider to be induced by human papillomavirus (HPV). Objective: To search for HPV in skin tumors, especially trichilemmomas, from patients with CS. Methods: Skin lesions from patients with CS were classified histologically. Each tumor was then analyzed for HPV DNA by polymerase chain reaction with different primer sets; positive amplicons were typed by direct sequencing. Results: Twenty-nine biopsies from 7 patients with CS were investigated. Only 2 of 29 tumors clinically suspected of being trichilemmomas were confirmed histologically. In addition, 3 sclerotic fibromas, also typical of CS, were found, as well as 1 sebaceous hyperplasia. The other 23 lesions showed histological features of HPV-induced tumors in various stages of development. HPV DNA was found in 19 of 29 cutaneous lesions. Tumors without any histological signs of HPV induction were negative for HPV DNA. Two tumors which were histologically classified as common warts contained HPV types 27 and 28. All the 17 other HPV types belong to the group of epidermodysplasia-verruciformis-associated types. Conclusions: The majority of cutaneous lesions in CS contain HPV DNA. They may have a variety of histological patterns. Trichilemmomas are not clinically distinctive and can be difficult to identify in CS patients. Copyright (C) 2003 S. Karger AG, Basel

Schwinger terms from geometric quantization of field theories

Geometric quantization is applied to infinite (countable) dimensional linear Kähler manifolds to obtain a closed expression for the anomalous commutator of arbitrary polynomial observables. Examples for the physical relevance of the result are given, including the polarization dependence of Schwinger terms in bilinear constraint algebras, the central terms of Virasoro and Kac-Moody algebras and the determination of the critical dimension of the bosonic string

Dirac Sigma Models

We introduce a new topological sigma model, whose fields are bundle maps from the tangent bundle of a 2-dimensional world-sheet to a Dirac subbundle of an exact Courant algebroid over a target manifold. It generalizes simultaneously the (twisted) Poisson sigma model as well as the G/G-WZW model. The equations of motion are satisfied, iff the corresponding classical field is a Lie algebroid morphism. The Dirac Sigma Model has an inherently topological part as well as a kinetic term which uses a metric on worldsheet and target. The latter contribution serves as a kind of regulator for the theory, while at least classically the gauge invariant content turns out to be independent of any additional structure. In the (twisted) Poisson case one may drop the kinetic term altogether, obtaining the WZ-Poisson sigma model; in general, however, it is compulsory for establishing the morphism property.Comment: 28 pages, Late

Maine Horseshoe Crab (Limulus polyphemus) Spawning Surveys, 2003

Maine spawning surveys of horseshoe crabs (Limulus polyphemus) continued for a third season in 2003. Survey sites were located in Yarmouth, Brunswick (2 sites), Woolwich, Nobleboro, Damariscotta, Sedgwick, Franklin and Sullivan. The purpose of this project is to establish quantitative baseline data on horseshoe crab populations in Maine as a basis for management of this species. The 2003 season recorded cooler than normal water temperatures through the end of May, which resulted in negligible activity during the initial historical May spawning period. Warmer water temperatures in June supported normal levels of spawning activity, as documented by the June counts. The tagging study on Taunton Bay in Franklin continued for a third year, with more observations (1255) and more individuals observed (900) than in 2002 (1119 and 741, respectively), but fewer than in 2001 (2273 and 1292 respectively). The overall data indicate that horseshoe crab populations are declining at all but two of the sites, both of which are in Brunswick

AsymmeTree: A Flexible Python Package for the Simulation of Complex Gene Family Histories

AsymmeTree is a flexible and easy-to-use Python package for the simulation of gene family histories. It simulates species trees and considers the joint action of gene duplication, loss, conversion, and horizontal transfer to evolve gene families along the species tree. To generate realistic scenarios, evolution rate heterogeneity from various sources is modeled. Finally, nucleotide or amino acid sequences (optionally with indels, among-site rate heterogeneity, and invariant sites) can be simulated along the gene phylogenies. For all steps, users can choose from a spectrum of alternative methods and parameters. These choices include most options that are commonly used in comparable tools but also some that are usually not found, such as the innovation model for species evolution. While output files for each individual step can be generated, AsymmeTree is primarily intended to be integrated in complex Python pipelines designed to assess the performance of data analysis methods. It allows the user to interact with, analyze, and possibly manipulate the simulated scenarios. AsymmeTree is freely available on GitHub