Solutions and approximations of some Lévy-driven stochastic (partial) differential equations

In this work we look at solutions to stochastic partial differential equations (SPDEs) with noise induced by a Lévy process in the context of Marcus integrals. The canonical Marcus integral is known from the study of SDEs with Lévy noise. We recapture the fundamental results on the existence of solution flows to the Marcus SDE and the convergence of Wong-Zakai approximations. We also prove a generalized Itô formula for said solutions and use this result to establish equations for the inverse flow. We are then looking at extensions of Marcus integrals to the case of SPDEs and find solutions for these equations. Our focus mainly lies on multi-dimensional first-order transport equations driven by Lévy noise. Existence and uniqueness results for the Marcus SPDE are established using a method of characteristics. For second-order equations we prove the existence and uniqueness of mild solutions for equations driven by pure jump Lévy processes, also in terms of Marcus SPDEs. Finally, we study a one-dimensional second-order advection-diffusion equation on the half-line, with Lévy noise at the boundary. Both Dirichlet and Neumann boundary conditions are considered, and the closed form formulae for mild solutions are determined. We also define Wong-Zakai type approximations of the solution by classical solutions and show convergence in the setting of the M1-topology in the Skorokhod space

Analysen zu Ausfällen (Unit-Nonresponse) im IAB-Betriebspanel (Analyses on unit-non-response in the IAB establishment panel)

"Within the framework of the IAB establishment panel more than 4000 establishments have been interviewed annually in western Germany since 1993 and the same number in eastern Germany since 1996. Although the response rate is high - also in comparison with other establishment surveys - the unit-non-response can cause distortions in the results if the non-response processes are systematic. In addition the distortions can increase over the course of time in the case of panel surveys in which the same study units are interviewed each year. Against this background the aim of this paper is to examine whether the occurrence of unit-non-response in the IAB establishment panel is connected with certain characteristics. The analyses refer to the longitudinal analysis of 1994 to 1997 for western Germany. On the whole the results do not indicate a selection of the participating establishments which is relevant as regards contents and which increases over the course of time. In addition to the reported analyses which should be continued, other further studies appear necessary: for instance relevant analyses should also be carried out for eastern Germany, it would make sense to do similar studies for the individual cross-sections, and also the item-non-response needs to be examined more closely." (Author's abstract, IAB-Doku) ((en))Panel - Konzeption, Antwortverhalten, IAB-Betriebspanel, Non Response

Reciprocal Interactions between Nematodes and Their Microbial Environments

Parasitic nematode infections are widespread in nature, affecting humans as well as wild, companion, and livestock animals. Most parasitic nematodes inhabit the intestines of their hosts living in close contact with the intestinal microbiota. Many species also have tissue migratory life stages in the absence of severe systemic inflammation of the host. Despite the close coexistence of helminths with numerous microbes, little is known concerning these interactions. While the environmental niche is considerably different, the free-living nematode Caenorhabditis elegans (C. elegans) is also found amongst a diverse microbiota, albeit on decaying organic matter. As a very well characterized model organism that has been intensively studied for several decades, C. elegans interactions with bacteria are much more deeply understood than those of their parasitic counterparts. The enormous breadth of understanding achieved by the C. elegans research community continues to inform many aspects of nematode parasitology. Here, we summarize what is known regarding parasitic nematode-bacterial interactions while comparing and contrasting this with information from work in C. elegans. This review highlights findings concerning responses to bacterial stimuli, antimicrobial peptides, and the reciprocal influences between nematodes and their environmental bacteria. Furthermore, the microbiota of nematodes as well as alterations in the intestinal microbiota of mammalian hosts by helminth infections are discussed

Influence of Immune Status on the Airborne Colonization of Piglets with Methicillin-Resistant Staphylococcus aureus (MRSA) Clonal Complex (CC) 398

Colonized vertebrates including humans and pigs are to date the main reservoirs of livestock-associated Methicillin-resistant Staphylococcus aureus (LA-MRSA). Currently, the mechanisms underlying colonization of pigs are not fully understood. We investigated the influence of piglet pre-immune status on airborne MRSA colonization. Three groups of MRSA-negative piglets were primed and exposed to airborne LA-MRSA (104 colony forming units (cfu)/m3) in an aerosol chamber for 24 h. One group was treated intramuscularly with dexamethasone (1 mg/kg body weight) to imitate weaning stress. The second group was exposed to bacterial endotoxin containing MRSA aerosol. Both conditions play a role in the development of multifactorial diseases and may promote MRSA colonization success. The third group served as control. The piglets' MRSA status was monitored for 21 days via swab samples. At necropsy, specific tissues and organs were analyzed. Blood was collected to examine specific immunological parameters. The duration of MRSA colonization was not extended in both treated groups compared to the control group, indicating the two immune-status influencing factors do not promote MRSA colonization. Blood sample analysis confirmed a mild dexamethasone-induced immune suppression and typical endotoxin-related changes in peripheral blood. Of note, the low-dose dexamethasone treatment showed a trend of increased MRSA clearance

Editorial: Parasite Infections: From Experimental Models to Natural Systems

Peer Reviewe

CD4+ Th immunogenicity of the Ascaris spp. secreted products

Ascaris spp. is a major health problem of humans and animals alike, and understanding the immunogenicity of its antigens is required for developing urgently needed vaccines. The parasite-secreted products represent the most relevant, yet complex (>250 proteins) antigens of Ascaris spp. as defining the pathogen-host interplay. We applied an in vitro antigen processing system coupled to quantitative proteomics to identify potential CD4+ Th cell epitopes in Ascaris-secreted products. This approach considerably restricts the theoretical list of epitopes using conventional CD4+ Th cell epitope prediction tools. We demonstrate the specificity and utility of our approach on two sets of candidate lists, allowing us identifying hits excluded by either one or both computational methods. More importantly, one of the candidates identified experimentally, clearly demonstrates the presence of pathogen-reactive T cells in healthy human individuals against these antigens. Thus, our work pipeline identifies the first human T cell epitope against Ascaris spp. and represents an easily adaptable platform for characterization of complex antigens, in particular for those pathogens that are not easily amenable for in vivo experimental validation