Agroeca dentigera and Entelecara omissa (Araneae: Liocranidae, Linyphiidae) found in Sweden

The rare spider species Agroeca dentigera Kulczyński, 1913 (Liocranidae) and Entelecara omissa O. P.-Cambridge, 1902 (Linyphiidae), have been found in a small coastal freshwater fen in Lomma (55°42'N 13°4'E), north of Malmö in Scania in southernmost Sweden. A. dentigera was also found on a salt water meadow south of Malmö. Both species have been found only in a few wet localities in Europe. Entelecara depilata Tullgren, 1955, is a junior synonym of Entelecara omissa O. P.-Cambridge, 1902, new synonymy

The distribution and habitat of Pocadicnemis pumila and P. juncea (Araneae, Linyphiidae) in Sweden

Two species of the genus Pocadicnemis (Araneae, Linyphiidae), P. pumila (Blackwall) and P. juncea (Locket & Millidge) have been reported from Scandinavia. In order to find out the distribution and differences in the habitat, all specimens of Pocadicnemis from the author's collection, the collection of Sven Almquist, the Swedish Museum of Natural History (including the collection of Tullgren), and the Zoological Museum of Lund have been checked

Avalanche size distribution in a random walk model

We introduce a simple model for the size distribution of avalanches based on the idea that the front of an avalanche can be described by a directed random walk. The model captures some of the qualitative features of earthquakes, avalanches and other self-organized critical phenomena in one dimension. We find scaling laws relating the frequency, size and width of avalanches and an exponent $4/3$ in the size distribution law.Comment: 16 pages Latex, macros included, 3 postscript figure

The phase diagram of an Ising model on a polymerized random surface

We construct a random surface model with a string susceptibility exponent one quarter by taking an Ising model on a random surface and introducing an additional degree of freedom which amounts to allowing certain outgrowths on the surfaces. Fine tuning the Ising temperature and the weight factor for outgrowths we find a triple point where the susceptibility exponent is one quarter. At this point magnetized and nonmagnetized gravity phases meet a branched polymer phase.Comment: Latex file, 10 pages, macros included. Two EPS figure

A Solvable 2D Quantum Gravity Model with \GAMMA >0

We consider a model of discretized 2d gravity interacting with Ising spins where phase boundaries are restricted to have minimal length and show analytically that the critical exponent $\gamma= 1/3$ at the spin transition point. The model captures the numerically observed behavior of standard multiple Ising spins coupled to 2d gravity.Comment: Latex, 9 pages, NBI-HE-94-0

Simulations of Dust in Interacting Galaxies

A new Monte-Carlo radiative-transfer code, Sunrise, is used to study the effects of dust in N-body/hydrodynamic simulations of interacting galaxies. Dust has a profound effect on the appearance of the simulated galaxies. At peak luminosities, about 90% of the bolometric luminosity is absorbed, and the dust obscuration scales with luminosity in such a way that the brightness at UV/visual wavelengths remains roughly constant. A general relationship between the fraction of energy absorbed and the ratio of bolometric luminosity to baryonic mass is found. Comparing to observations, the simulations are found to follow a relation similar to the observed IRX-Beta relation found by Meurer et al (1999) when similar luminosity objects are considered. The highest-luminosity simulated galaxies depart from this relation and occupy the region where local (U)LIRGs are found. This agreement is contingent on the presence of Milky-Way-like dust, while SMC-like dust results in far too red a UV continuum slope to match observations. The simulations are used to study the performance of star-formation indicators in the presence of dust. The far-infrared luminosity is found to be reliable. In contrast, the H-alpha and far-UV luminosity suffer severely from dust attenuation, and dust corrections can only partially remedy the situation.Comment: 4 pages, 5 figures, to appear in the proceedings of the conference "The Spectral Energy Distribution of Gas-Rich Galaxies", eds. C.C. Popescu & R.J. Tuffs (Heidelberg, October 2004