On a gauge invariant description of soliton dynamics

We present important elements of a gauge and diffeomorphism invariant formulation of the moduli space approximation to soliton dynamics. We argue that explicit velocity-dependent modifications are determined entirely from gauge and diffeomorphism invariance. We illustrate the formalism for the case of a Yang-Mills theory on a curved spacetime background.Comment: 8 pages, contribution to the proceedings of the 35th Ahrenshoop Symposium, 200

Regulations in Biotechnology: Administrative Handling and Scientific Content

The administrative handling of regulatory oversight procedures differs from country to country, whereas the scientific data required for the safety assurance are similiar in most instances. Safety issues for contained biotechnology applications are mainly a matter between industry and the government agencies involved. Deliberate release of transgenic organisms and the market introduction of transgenic food, however, produce much public debate. It is assumed that shortcomings related to risk-assessment methodology as, e.g., the lack of accepted protection goals and the continuing discussions about the validity of comparative risk assessment may be reasons for the current situation

Planned Releases of Genetically Modified Organisms into the Environment: the Evolution of Safety Considerations

Issues of safety and risk have taken the foreground in discussions on the deliberate release of genetically modified organisms. In most cases, the organisms being introduced into the environment are modified versions of familiar organisms with a long history of safe use and are expected to have no direct adverse effects for human health or for the environment. However, there is legitimate concern about the environmental fate of these organisms, in particular, about the genetic information which they carry. In the past, discussions of technological risk have often been based on the terminology and logic of the familiar risk-assessment strategy developed for characterizing risks from hazardous chemical processes. While the direct transfer of this assessment model to evaluating contained biotechnological processes has been successful, attempts at molding the model to the requirements of open systems have been unsatisfactory. To be meaningful, the safety evaluation for environmental releases must accomodate the distinguishing features of this open system: the lack of an intrinsic hazardous property, the lack of quantitative thresholds for adverse effects, and the lack of a common currency in which to express potential damages. A survey of risk-assessment strategies in the chemical and biotechnological sectors is presented here. This will provide the necessary background to understanding the current situation of assessing and communicating the risks associated with the reintroduction of familiar organisms into environments where they were already naturally present

Well-balanced finite volume schemes for nearly steady adiabatic flows

We present well-balanced finite volume schemes designed to approximate the Euler equations with gravitation. They are based on a novel local steady state reconstruction. The schemes preserve a discrete equivalent of steady adiabatic flow, which includes non-hydrostatic equilibria. The proposed method works in Cartesian, cylindrical and spherical coordinates. The scheme is not tied to any specific numerical flux and can be combined with any consistent numerical flux for the Euler equations, which provides great flexibility and simplifies the integration into any standard finite volume algorithm. Furthermore, the schemes can cope with general convex equations of state, which is particularly important in astrophysical applications. Both first- and second-order accurate versions of the schemes and their extension to several space dimensions are presented. The superior performance of the well-balanced schemes compared to standard schemes is demonstrated in a variety of numerical experiments. The chosen numerical experiments include simple one-dimensional problems in both Cartesian and spherical geometry, as well as two-dimensional simulations of stellar accretion in cylindrical geometry with a complex multi-physics equation of state

Stationary Configurations and Geodesic Description of Supersymmetric Black Holes

This thesis contains a detailed study of various properties of supersymmetric black holes. In chapter I an overview over some of the fascinating aspects of black hole physics is provided. In particular, the string theory approach to black hole entropy is discussed. One of the consequences of the string theory results is that black hole entropy can be understood within the context of an effective field theory only if one resorts to supergravity theories with higher-order curvature interactions. To this extent, some relevant elements of N=2 supersymmetric theories and supergravity theories are introduced in chapter II. In chapter III N=2 supergravity theories with higher-order curvature interactions are described. Chapter IV contains a classification of the fully supersymmetric vacua and a characterization of a large class of stationary BPS black hole configurations in the presence of higher-derivative interactions. In chapter V the derivation of the macroscopic entropy formula appropriate for theories with higher-order curvature interactions is reviewed and compared to the results of string theory. Furthermore, in the absence of higher-order curvature interactions, the metric on the moduli space of simple multi-centered black hole solutions is calculated. In chapter VI, finally, a formalism to derive the geodesic description of generic gravitational solitons is developed

A note on topological amplitudes in hybrid string theory

We study four-dimensional compactifications of type II superstrings on Calabi-Yau spaces using the formalism of hybrid string theory. Chiral and twisted-chiral interactions are rederived, which involve the coupling of the compactification moduli to two powers of the Weyl-tensor and of the derivative of the universal tensor field-strength

An Advanced Leakage Scheme for Neutrino Treatment in Astrophysical Simulations

We present an Advanced Spectral Leakage (ASL) scheme to model neutrinos in the context of core-collapse supernovae (CCSNe) and compact binary mergers. Based on previous gray leakage schemes, the ASL scheme computes the neutrino cooling rates by interpolating local production and diffusion rates (relevant in optically thin and thick regimes, respectively) separately for discretized values of the neutrino energy. Neutrino trapped components are also modeled, based on equilibrium and timescale arguments. The better accuracy achieved by the spectral treatment allows a more reliable computation of neutrino heating rates in optically thin conditions. The scheme has been calibrated and tested against Boltzmann transport in the context of Newtonian spherically symmetric models of CCSNe. ASL shows a very good qualitative and a partial quantitative agreement for key quantities from collapse to a few hundreds of milliseconds after core bounce. We have proved the adaptability and flexibility of our ASL scheme, coupling it to an axisymmetric Eulerian and to a three-dimensional smoothed particle hydrodynamics code to simulate core collapse. Therefore, the neutrino treatment presented here is ideal for large parameter-space explorations, parametric studies, high-resolution tests, code developments, and long-term modeling of asymmetric configurations, where more detailed neutrino treatments are not available or are currently computationally too expensive

Magnetorotationally driven Supernovae as the origin of early galaxy rr-process elements?

We examine magnetorotationally driven supernovae as sources of $r$-process elements in the early Galaxy. On the basis of thermodynamic histories of tracer particles from a three-dimensional magnetohydrodynamical core-collapse supernova model with approximated neutrino transport, we perform nucleosynthesis calculations with and without considering the effects of neutrino absorption reactions on the electron fraction ($Y_{e}$) during post-processing. We find that the peak distribution of $Y_{e}$ in the ejecta is shifted from $\sim0.15$ to $\sim0.17$ and broadened toward higher $Y_{e}$ due to neutrino absorption. Nevertheless, in both cases the second and third peaks of the solar $r$-process element distribution can be well reproduced. The rare progenitor configuration that was used here, characterized by a high rotation rate and a large magnetic field necessary for the formation of bipolar jets, could naturally provide a site for the strong $r$-process in agreement with observations of the early galactic chemical evolution.Comment: 5 pages, 4 figure