High-Temperature Series Expansions for Random Potts Models

We discuss recently generated high-temperature series expansions for the free energy and the susceptibility of random-bond q-state Potts models on hypercubic lattices. Using the star-graph expansion technique quenched disorder averages can be calculated exactly for arbitrary uncorrelated coupling distributions while keeping the disorder strength p as well as the dimension d as symbolic parameters. We present analyses of the new series for the susceptibility of the Ising (q=2) and 4-state Potts model in three dimensions up to order 19 and 18, respectively, and compare our findings with results from field-theoretical renormalization group studies and Monte Carlo simulations.Comment: 16 pages,cmp209.sty (included), 9 postscript figures, author information under http://www.physik.uni-leipzig.de/index.php?id=2

The Former Geiseltal Museum (1934-2011), the Eocene Geiseltal Fossilagerstätte (Germany) and the Scientific Meaning of Ben Barnes as a Pioneer of Systematic Quantitative Vertebrate Excavations in the Geiseltal Lignites

The Geiseltal was a productive area for mining of lignite (brown coal) for about 100 years in central Germany (state of Saxony-Anhalt). Recognition of the scientific value of its famous fossil content came about in the 1920s, and from the early 1930s onwards Geiseltal is known as a unique Eocene terrestrial/palustrial Fossillagerstätte. During your professorship and position as Head of the geological Institute in Halle (Saale) in the 1920s, he focused more and more on the famous and outstanding finds of fossils in the middle Eocene brown coal of the Geiseltal. Ben Barnes was the pioneer of systematic and quantitative vertebrate excavations in the Geiseltal lignites. With his successful work, undertaken using with modern scientific aspects of his time, he gave rise for many other researchers to do so in the same way and to contribute step by step in reconstructing the geological and palaeontological history of fauna, flora and palaeoenvironment etc. in the Geiseltal

The role of IL-18 and IL-1 receptor signaling in T cell development and T cell exhaustion in a murine pancreatic cancer model

Pancreatic cancer is one of the deadliest cancer types and is characterized by a highly immunosuppressive tumor microenvironment. The abundance of T cells in the tumor microenvironment has been shown to improve the prognosis for pancreatic cancer patients. Nevertheless, T cell exhaustion can cause a lack T cell effector function and therefore contribute to cancer immune evasion. Cytokines, like the NLRP3-dependent cytokines IL-18 and IL-1β, are highly involved in the regulation of the function and exhaustion of T cells. Additionally, elevated levels of IL-18 and IL-1β have been found in various cancer types, inter alia pancreatic cancer. Therefore, this study aimed to characterize the role of IL-18 and IL-1β in T cell exhaustion and dysfunction in a pancreatic cancer model. It is highly important to understand the function and plasticity of T cells in pancreatic cancer in order to find new therapy approaches. Therefore, the goal of this study was to determine i) the effect of IL-18 on T cell exhaustion in vitro, ii) the molecular mechanisms of IL-18-mediated exhaustion of CTLs, iii) the effects of IL-1β and IL-18 on Th1 and Treg differentiation in vitro, iv) the effect of IL-1R and IL-18R signaling in adoptively transferred CD4+ T cells on endogenous T cell populations in a murine pancreatic cancer model and v) the effect of IL-1R and IL-18R signaling in adoptively transferred CD4+ T cells on tumor rejection and on the function of adoptively transferred tumor specific CTLs in a murine pancreatic cancer model. During this study, an in vitro exhaustion model was used which showed that IL-18 induces a more severe exhausted phenotype of antigen-specific CD8+ T cells in vitro. Additionally, it was used to determine that the IL-2/STAT5/Akt/mTOR pathway plays a key role in the IL-18 mediated induction of exhaustion. Therefore, this study identified IL-18 and the IL-2/STAT5/Akt/mTOR pathway as potential targets for immunotherapy in cancer. This study also revealed a Th1 inducing and iTreg inhibiting function of IL-18 receptor signaling in vitro and therefore provides valuable information on IL-18 receptor signaling in CD4+ T cell subsets that are important for future in vitro and in vivo studies. IL-18R and IL-1R signaling in adoptively transferred CD4+ T cells in a murine pancreatic cancer model neither had an impact on endogenous CD4+ or CD8+ T cells nor did they influence tumor growth or tumor rejection by antigen-specific CTLs. Nevertheless, the mice strains generated during this study are a helpful tool for future studies focusing on the role of IL-18 and IL-1 receptor signaling in antigen-specific CD4+ T cells and Tregs

The diversity of odonata and their endophytic ovipositions from the upper oligocene fossillagerstätte of rott (Rhineland, Germany)

A commented list of fossil Odonata from the Oligocene outcrop of Rott is given, together with descriptions of new traces of oviposition in plant tissues, very similar to ichnotaxa already known from the early Eocene Laguna del Hunco floras of Patagonia. The joint presences of odonatan larvae and traces of oviposition demonstrate the autochthony of these insects in the palaeolake of Rott, confirming the existence of a diverse and abundant aquatic entomofauna, a situation strikingly different to that in the contemporaneous Oligocene palaeolake of Céreste (France).Fil: Petrulevicius, Julian Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleozoología Invertebrados; ArgentinaFil: Wappler, Torsten. Universitat Bonn; AlemaniaFil: Nel, André. Muséum National d'Histoire Naturelle; FranciaFil: Rust, Jes. Universitat Bonn; Alemani

Geometrical Phase Transitions

The geometrical approach to phase transitions is illustrated by simulating the high-temperature representation of the Ising model on a square lattice.Comment: 5 pages, 3 figures, talk presented at Conference on Computational Physics 2004, Genoa, 1-4 September 2004; 2nd version: slightly expanded versio

High-temperature series for the bond-diluted Ising model in 3, 4 and 5 dimensions

In order to study the influence of quenched disorder on second-order phase transitions, high-temperature series expansions of the \sus and the free energy are obtained for the quenched bond-diluted Ising model in $d = 3$--5 dimensions. They are analysed using different extrapolation methods tailored to the expected singularity behaviours. In $d = 4$ and 5 dimensions we confirm that the critical behaviour is governed by the pure fixed point up to dilutions near the geometric bond percolation threshold. The existence and form of logarithmic corrections for the pure Ising model in $d = 4$ is confirmed and our results for the critical behaviour of the diluted system are in agreement with the type of singularity predicted by renormalization group considerations. In three dimensions we find large crossover effects between the pure Ising, percolation and random fixed point. We estimate the critical exponent of the \sus to be $\gamma =1.305(5)$ at the random fixed point.Comment: 16 pages, 10 figure