Hydrillae (Hydrocharitaceae) in Europe. [translation of key to Hydrilla only] [Translation from: Goettinger Floristische Rundbriefe 14 33-56, 1980]

This partial translation of a bigger publication provides an identification key to the aquatic plant Hydrillae (Hydrocharitaceae) in Europe. Illustrations are included

The Speed of Leaving the Old Job: A Study on Job Changes and Exit into Unemployment during the East German Transition Process

The first period of the transition to a market economy was characterised by a high rate of job-change in many transition countries. This was no different for East Germany. This paper analyses the consequences of the transition process for East German workers in their old job. We quantify the speed at which they change their jobs for a new one or enter unemployment by studying a sample of job spells drawn form the German Socio-Economic Panel-East. The study focuses the period from July 1990 to December 1993, thus a period after the introduction of the German Economic, Monetary, and Social Union. We estimate the effects of important covariates on the transition rates from the old job into a new and into unemployment by a standard competing-risks duration model. Our results suggest that the speed of exit into new jobs rises with skills. We also find that old firms managed to keep workers with relatively good job matches. The special short-time allowances, a labour market program that was in force until the end of 1991, slowed down the exit rate into unemployment prior to its end. We find that workers increased their rate of job-change temporarily at around the period in which this program ended

Simulation of Field Theories in Wavelet Representation

The field is expanded in a wavelet series and the wavelet coefficients are varied in a simulation of the 2D $\phi^4$ field theory. The drastically reduced autocorrelations result in a substantial decrease of computing requirements, compared to those in local Metropolis simulations. A large part of the improvement is shown to be the result of an additional freedom in the choice of the allowed range of change at the Metropolis update of wavelet components, namely the range can be optimized independently for all wavelet sizes.Comment: 10 pages, LaTeX with 8 figures, Swansea preprint SWAT/3

Kakeya sets over non-archimedean local rings

In a recent paper of Ellenberg, Oberlin, and Tao, the authors asked whether there are Besicovitch phenomena in F_q[[t]]^n. In this paper, we answer their question in the affirmative by explicitly constructing a Kakeya set in F_q[[t]]^n of measure 0. Furthermore, we prove that any Kakeya set in F_q[[t]]^2 or Z_p^2 is of Minkowski dimension 2.Comment: 10 page

Surface properties of ocean fronts

Background information on oceanic fronts is presented and the results of several models which were developed to study the dynamics of oceanic fronts and their effects on various surface properties are described. The details of the four numerical models used in these studies are given in separate appendices which contain all of the physical equations, program documentation and running instructions for the models

Critical exponents of a three dimensional O(4) spin model

By Monte Carlo simulation we study the critical exponents governing the transition of the three-dimensional classical O(4) Heisenberg model, which is considered to be in the same universality class as the finite-temperature QCD with massless two flavors. We use the single cluster algorithm and the histogram reweighting technique to obtain observables at the critical temperature. After estimating an accurate value of the inverse critical temperature \Kc=0.9360(1), we make non-perturbative estimates for various critical exponents by finite-size scaling analysis. They are in excellent agreement with those obtained with the $4-\epsilon$ expansion method with errors reduced to about halves of them.Comment: 25 pages with 8 PS figures, LaTeX, UTHEP-28

Finite Size Analysis of the U(1) Background Field Effective Action

We apply the finite size scaling analysis to the derivative of the density of the effective action for the lattice U(1) pure gauge theory in an external constant magnetic field. We found the presence of a continuous phase transition. Moreover, our extimate of of the critical parameters gives values consistent with those extracted from the analysis of the specific heat.Comment: LaTeX2e, 12 pages (5 figures