N-fold way simulated tempering for pairwise interaction point processes

Pairwise interaction point processes with strong interaction are usually difficult to sample. We discuss how Besag lattice processes can be used in a simulated tempering MCMC scheme to help with the simulation of such processes. We show how the N-fold way algorithm can be used to sample the lattice processes efficiently and introduce the N-fold way algorithm into our simulated tempering scheme. To calibrate the simulated tempering scheme we use the Wang-Landau algorithm

Extracellular ATP drives systemic inflammation, tissue damage and mortality

Systemic inflammatory response syndromes (SIRS) may be caused by both infectious and sterile insults, such as trauma, ischemia-reperfusion or burns. They are characterized by early excessive inflammatory cytokine production and the endogenous release of several toxic and damaging molecules. These are necessary to fight and resolve the cause of SIRS, but often end up progressively damaging cells and tissues, leading to life-threatening multiple organ dysfunction syndrome (MODS). As inflammasome-dependent cytokines such as interleukin-1 beta are critically involved in the development of MODS and death in SIRS, and ATP is an essential activator of inflammasomes in vitro, we decided to analyze the ability of ATP removal to prevent excessive tissue damage and mortality in a murine LPS-induced inflammation model. Our results indeed indicate an important pro-inflammatory role for extracellular ATP. However, the effect of ATP is not restricted to inflammasome activation at all. Removing extracellular ATP with systemic apyrase treatment not only prevented IL-1 beta accumulation but also the production of inflammasome-independent cytokines such as TNF and IL-10. In addition, ATP removal also prevented systemic evidence of cellular disintegration, mitochondrial damage, apoptosis, intestinal barrier disruption and even mortality. Although blocking ATP receptors with the broad-spectrum P2 purinergic receptor antagonist suramin imitated certain beneficial effects of apyrase treatment, it could not prevent morbidity or mortality at all. We conclude that removal of systemic extracellular ATP could be a valuable strategy to dampen systemic inflammatory damage and toxicity in SIRS

The effects of diel vertical migration of Daphnia on zooplankton-phytoplankton interactions

Zooplankton populations which perform diel vertical migration (DVM) only spend the night in surface water layers but migrate downwards into the lower water layers during the day. The intention of this study was to investigate effects of DVM of Daphnia on phytoplankton dynamics and Daphnia life history parameters in a lake. I conducted field and laboratory experiments in which I compared ‘migration’ with ‘no-migration’ situations. It is generally assumed that phytoplankton communities in the epilimnion of stratified lakes profit from the presence of DVM. This might be caused by less grazing due to intermittent grazing and/or less grazing due to lower population densities of migrating Daphnia populations (as they migrate into the colder, lower hypolimnion during the day which leads to a lower temperature-dependent population growth). In a first laboratory experiment I showed that an enhanced phytoplankton biomass could develop under a migration regime solely due to intermittent grazing. I further showed that edible phytoplankton species with higher intrinsic growth rates benefited more from intermittent grazing than edible species with lower intrinsic growth rates. Field experiments also indicated that phytoplankton biomass in the epilimnion was higher when subject to a migrating zooplankton population and that additionally different phytoplankton community compositions arose from different migration regimes (‘migration’/’no-migration’). For example edible algae were at an advantage when zooplankton migrated, whereas large, inedible algae species had an advantage when zooplankton populations did not migrate. In an additional laboratory experiment I also showed that these changes in phytoplankton composition had strong feedback effects on life history parameters of daphnids and that food conditions experienced by migrating daphnids were advantageous. In a further laboratory experiment I exposed two Daphnia species to either constant or regularly changing temperature regimes to study whether a fluctuating temperature regime – as experienced by migrating daphnids – implies costs for daphnids. Somatic growth rates of juvenile Daphnia in the regularly changing temperature regime were almost as low as under constant low temperature conditions indicating that a regular change in temperature involves high costs. The results of my study indicate that DVM has a strong modulating effect on zooplankton-phytoplankton interactions in a lake.Zooplankter, die eine tagesperiodischen Vertikalwanderung (TPV) durchführen halten sich nur nachts in der Oberflächenschicht der Gewässer auf, den Tag dagegen verbringen sie in tieferen Schichten. Die vorliegende Arbeit beschäftigt sich mit den Auswirkungen der TPV von Daphnien auf Phytoplanktondynamiken und Populationsparameter der Daphnien. Dazu führte ich sowohl Freiland- als auch Laborversuche durch, in denen ich jeweils ‘Migrations-’ mit ‘Nicht-Migrations-’ Ansätzen verglich. Es wird generell angenommen, dass Phytoplanktongemeinschaften in den Epilimnien von geschichteten Seen der gemäßigten Zone von einer TPV profitieren können. Das kann durch zwei Mechanismen hervorgerufen werden: Erstens durch einen zeitlich gepulsten Fraßdruck (Grazing nur nachts), und zweitens durch einen geringeren Fraßdruck, hervorgerufen durch die meist geringere Dichte wandernder Zooplanktonpopulationen, da diese, bedingt durch die Wanderung tagsüber in die kalten, tiefergelegenen Wasserschichten, ein reduziertes Wachstum haben. In einem ersten Laborversuch konnte ich zeigen, dass allein durch einen zeitlich gepulsten, diskontinuierlichen Fraßdruck ein erhöhtes Algenwachstum entstehen konnte. Ich konnte weiterhin zeigen, dass fressbare Algenarten mit einer höheren intrinsischen Wachstumsrate einen größeren Vorteil von der TPV hatten als fressbare Arten mit einer niedrigeren Wachstumsrate. In Freilandexperimenten konnte ich zum einen ebenfalls zeigen, dass die Algenbiomasse bei Wanderung der Daphnien erhöht war, zum anderen konnte ich auch vom Wanderregime abhängige Veränderungen in der Phytoplanktongemeinschaft nachweisen. So hatten fressbare Phytoplanktonarten einen Vorteil von einer TPV, unfressbare Algenarten hatten dagegen einen Vorteil, wenn keine Wanderung stattfand. Ich konnte in einem weiteren Laborversuch zeigen, dass die oben genannten Veränderungen in der Phytoplanktondynamik starke rückwirkende Effekte auf Populationsparameter der Daphnien hatten. In einem weiteren Laborversuch setzte ich die Daphnien entweder konstanten, oder tageszeitenabhängig fluktuierenden Temperaturregimes aus. Dadurch untersuchte ich, ob eine sich zwei mal pro Tag ändernde Temperatur (wie Daphnien es bei einer Wanderung erleben) Kosten für Daphnien verursacht. Dabei war die somatische Wachstumsrate der juvenilen Daphnien bei einem fluktuierenden Temperaturregime fast genauso gering wie bei konstant tiefer Temperatur. Dies gibt Hinweise auf Kosten, die durch ein fluktuierendes Temperaturregime entstehen. Die Ergebnisse zeigen, dass eine TPV von Daphnien starke, modulierende Auswirkungen auf Zooplankton-Phytoplankton Interaktionen hat

Management Attitudes towards HRM Practices and Works Council Presence in German SMEs

This paper examines the impact of management attitudes towards human resource management (HRM) practices on the presence of works councils in German small and medium-sized enterprises (SMEs). Based on a survey among executives of German SMEs, the key result of a logit regression analysis is that managers’ attitudes towards key HRM practices have a strong impact on the prevalence of the works council in German SMEs. In particular, positive management attitudes towards individual employee participation and direct supervision seem to be detrimental for the institutionalization of works councils. The results suggest that there is more diversity and management choice regarding the institutions of industrial relations than generally expected in the case of German firms

The Financial Cost of Sadness

This paper hypothesizes a phenomenon—myopic misery—in which sadness creates a myopic focus on obtaining money now versus later, increasing intertemporal discount rates and thereby producing substantial financial costs. Experiments 1-3 randomly assigned participants to a sad- or neutral-mood condition, and then offered intertemporal choices. Disgust served as a comparison condition in Experiments 1-2. Results revealed that sadness significantly increased impatience: Relative to median neutral-mood participants, median sad-mood participants accepted 13% to 34% less money today to avoid waiting three months for payment. Impatient thoughts mediated the effects. Disgusted participants were not more impatient than neutral participants, implying that the financial effects do not arise from all negative emotions. The paper concludes that myopic misery is a robust and potentially harmful phenomenon

Two cases of feline pyothorax : medical versus surgical treatment and associated challenges

Pyothorax is a rare disease in cats. Underlying causes and treatment recommendations vary greatly between cases. In this case series, the management of two challenging cases of feline pyothorax is discussed. In the first case, a nine-year-old female spayed European shorthair cat with pyothorax caused by Bacteroides fragilis is described. At the time of presentation, she was diagnosed with feline immunodeficiency virus as well. The pyothorax was succesfully managed medically. Unfortunately, the cat relapsed after three months and the owner elected euthanasia. The second case involved a ten-year-old male castrated British shorthair cat with identification of filamentous bacteria on pleural fluid cytology. This cat underwent surgical intervention because thoracic drainage was very difficult. Eventually, he recovered well and did not relapse up to two months postoperatively. The challenges in the decision process and treatment complications are discussed

Green consumer markets in the fight against climate change

Climate change has become one of the greatest threats to environmental security, as attested by the growing frequency of severe flooding and storms, extreme temperatures and droughts. Accordingly, the European Union’s (EU) 6th Environment Action Programme (2010) lists tackling climate change as its first priority. A key aim of the EU has been to cut CO2 emissions, a major factor in climate change, by 8% until 2012 and 20% until 2020. The European Commission has proposed the encouragement of private consumer market for green products and services as one of several solutions to this problem. However, existing research suggests that the market share of these products has been only 3%, although 30% of individuals favour environmental and ethical goods. This article uses Public Goods Theory to explain why the contribution of the green consumer market to fighting climate change has been and possibly may remain limited without further public intervention