Sulphur and Carbon Isotopes as Tracers of Past Sub-seafloor Microbial Activity

Microbial life below the seafloor has changed over geological time, but these changes are often not obvious, as they are not recorded in the sediment. Sulphur (S) isotope values in pyrite extracted from a Plio- to Holocene sequence of the Peru Margin (Ocean Drilling Program, ODP, Site 1229) show a down-core pattern that correlates with the pattern of carbon (C) isotopes in diagenetic dolomite. Early formation of the pyrite is indicated by the mineralogical composition of iron, showing a high degree of pyritization throughout the sedimentary sequence. Hence, the S-record could not have been substantially overprinted by later pyrite formation. The S- and C-isotope profiles show, thus, evidence for two episodes of enhanced microbial methane production with a very shallow sulphate-methane transition zone. The events of high activity are correlated with zones of elevated organic C content in the stratigraphic sequence. Our results demonstrate how isotopic signatures preserved in diagenetic mineral phases provide information on changes of past biogeochemical activity in a dynamic sub-seafloor biosphere

Bildung und Qualifikation als Grundlage der technologischen Leistungsfähigkeit Deutschlands: Bericht des Konsortiums "Bildungsindikatoren und technologische Leistungsfähigkeit"

Die ausreichende Verfügbarkeit von hochqualifizierten Fachkräften wird zunehmend zum Schlüsselfaktor für die Wettbewerbs- und Innovationsfähigkeit - sowohl auf der Ebene von Unternehmen als auch auf der Ebene der Gesamtwirtschaft. Die vorliegende Studie beschäftigt sich daher mit Qualifikationen - insbesondere auf akademischem bzw. wissenschaftlichem Niveau, aber auch mit Qualifikationen, die in der beruflichen Bildung erworben werden - als Grundlage der technologischen Leistungsfähigkeit Deutschlands. Die hierfür maßgeblichen Indikatoren werden in der Zeitreihe und - soweit möglich - in international vergleichender Perspektive berichtet. Die Studie untersucht zunächst die in der Gesamtbevölkerung sowie die unter den Erwerbstätigen vorhandenen Qualifikationsstrukturen. Es zeigt sich, dass die Wissensintensivierung im Beschäftigungssystem auch während der Wirtschafts- und Finanzkrise in den Jahren 2008 bis 2010 vorangeschritten ist und die Nachfrage nach hochqualifizierten Beschäftigten weiter zunimmt. Trotz des Anstiegs des Anteils der Akademiker(innen) an allen Erwerbstätigen ist ihr Anteil in Deutschland im internationalen Vergleich noch immer sehr gering (ISCED 5A+6). Für Deutschland kommen die Analysen außerdem zu dem Schluss, dass die absolute Zahl der Akademiker(innen) im erwerbsfähigen Alter, unabhängig von ihrem Erwerbsstatus, bereits rückläufig ist. Dies kann als Hinweis auf erste Auswirkungen des demografischen Wandels interpretiert werden

The role of Dickkopf-3 in tissue mediated immune modulation

The immune system protects our organism from harmful environmental insults. Pathogens induce innate and adaptive immune responses that resolve infection and clear damaged cells. A tight balance between efficient elimination of the initial insult and the containment of the immune response, assures protection of the organism as well as the preservation of organ integrity. Disregulation of this system can lead to devastating effects like tissue damage and organ failure caused by excessive inflammation. Tissue components play a pivotal role in the regulation of immune responses. In order to develop novel therapeutic strategies for the treatment of inflammatory diseases, their properties have to be incorporated. Hence, a detailed understanding of mechanisms by which tissue cells influence immune responses is indispensable. Recently, our lab identified Dickkopf-3 (Dkk3) as an immune modulator mainly expressed by tissue cells. Thus we aimed to uncover the contribution of Dkk3 to tissue mediated immune modulation during inflammation. With the help of a transgenic mouse model we investigated how antigen-presenting keratinocytes in the inflamed skin modulate T cell reactivity. In these mice, keratinocytes present a myelin basic protein (MBP) peptide only upon skin inflammation. In the absence of systemic MBP immunization acute skin inflammation resulted in keratinocyte-mediated activation of MBP-specific CD4+ T cells that were encephalitogenic. However, chronic skin inflammation limited the encephalitogenic potential of systemically primed MBP-specific T cells. In this setting Dickkopf-3 was indispensable for the limitation of CD4 T cell reactivity. We successfully generated a transgenic Dkk3 reporter mouse that reliably indicates sites of Dkk3 expression. Furthermore, in vitro and in vivo studies identified interferon-γ (IFNγ) as a potent regulator of Dkk3 expression in tissue cell. Finally, we found that Dkk3 promotes the development of renal fibrosis in 2 different mouse models, indicated by decreased severity of fibrosis in Dkk3 deficient mice. Furthermore, we observed that Dkk3 expression is induced in tubular epithelial cells in the course of fibrosis development. Less fibrosis in Dkk3 deficient mice was accompanied by elevated levels of pro-inflammatory cytokines and increased T cell infiltration in the respective kidneys. Additionally, we observed an altered polarization of infiltrating CD4 T cells towards a Th1/Treg phenotype in dkk3-/- kidneys, which came along with decreased expression of Wnt target genes in these cells. In conclusion, Dkk3 contributes to tissue mediated immune modulation by regulation of T cell responses

Ultra-thin Topological Insulator Bi2Se3 Nanoribbons Exfoliated by Atomic Force Microscopy

Ultra-thin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak Van der Waals interaction between adjacent quintuple layers (QLs), the layered bismuth selenide (Bi2Se3), a single Dirac-cone topological insulator with a large bulk gap, can be exfoliated down to a few QLs. In this paper, we report the first controlled mechanical exfoliation of Bi2Se3 nanoribbons (> 50 QLs) by an atomic force microscope (AFM) tip down to a single QL. Microwave impedance microscopy is employed to map out the local conductivity of such ultra-thin nanoribbons, showing drastic difference in sheet resistance between 1~2 QLs and 4~5 QLs. Transport measurement carried out on an exfoliated (\leq 5 QLs) Bi2Se3 device shows non-metallic temperature dependence of resistance, in sharp contrast to the metallic behavior seen in thick (> 50 QLs) ribbons. These AFM-exfoliated thin nanoribbons afford interesting candidates for studying the transition from quantum spin Hall surface to edge states

Bildung und Qualifikation als Grundlage der technologischen Leistungsfähigkeit Deutschland: Bericht des Konsortiums "Bildungsindikatoren und technologische Leistungsfähigkeit"

Die ausreichende Verfügbarkeit von hochqualifizierten Fachkräften ist ein Schlüsselfaktor für die Wettbewerbs- und Innovationsfähigkeit - sowohl auf der Ebene von Unternehmen als auch auf der Ebene der Gesamtwirtschaft. Die vorliegende Studie beschäftigt sich daher mit Qualifikationen - insbesondere auf akademischem bzw. wissenschaftlichem Niveau, aber auch mit Qualifikationen, die in der beruflichen Bildung erworben werden - als Grundlage der technologischen Leistungsfähigkeit Deutschlands. Die hierfür maßgeblichen Indikatoren werden in der Zeitreihe und - soweit möglich - in international vergleichender Perspektive berichtet. In den im Fokus stehenden MINT-Fächern werden wichtige Fachkräftepotenziale bislang vor allem durch die unterdurchschnittliche Beteiligung von Frauen nicht ausgeschöpft. Der diesjährige Bericht analysiert daher schwerpunktmäßig die wichtigsten Indikatoren zur Bildungs- und Erwerbsbeteiligung von Frauen in den Ingenieur- und Naturwissenschaften. Die Studie untersucht zunächst die in der Gesamtbevölkerung sowie unter den Erwerbstätigen vorhandenen Qualifikationsstrukturen (Kap. 2). Insgesamt entwickelt sich die Erwerbstätigkeit von Hochqualifizierten in Deutschland deutlich weniger dynamisch als in wichtigen europäischen Vergleichsländern. Es fällt allerdings auf, dass - im Gegensatz zu den Referenzländern - das Wachstum des Anteils der Hochqualifizierten unter den Erwerbstätigen in Deutschland höher ausfällt als die Bildungsexpansion in der Bevölkerung insgesamt. Dahinter steht eine Mobilisierung des Potenzials von Hochqualifizierten unter den Erwerbslosen bzw. Nichterwerbspersonen, die darauf hindeutet, dass die Nachfrage nach Hochqualifizierten in Deutschland stärker angewachsen ist als das Angebot. Damit korrespondiert, dass die Arbeitslosigkeit unter Hochqualifizierten nicht - wie in vielen anderen Ländern im Zuge der Wirtschafts- und Finanzkrise - angestiegen ist

miRA: adaptable novel miRNA identification in plants using small RNA sequencing data

BACKGROUND: MicroRNAs (miRNAs) are short regulatory RNAs derived from longer precursor RNAs. miRNA biogenesis has been studied in animals and plants, recently elucidating more complex aspects, such as non-conserved, species-specific, and heterogeneous miRNA precursor populations. Small RNA sequencing data can help in computationally identifying genomic loci of miRNA precursors. The challenge is to predict a valid miRNA precursor from inhomogeneous read coverage from a complex RNA library: while the mature miRNA typically produces many sequence reads, the remaining part of the precursor is covered very sparsely. As recent results suggest, alternative miRNA biogenesis pathways may lead to a more diverse miRNA precursor population than previously assumed. In plants, the latter manifests itself in e.g. complex secondary structures and expression from multiple loci within precursors. Current miRNA identification algorithms often depend on already existing gene annotation, and/or make use of specific miRNA precursor features such as precursor lengths, secondary structures etc. Consequently and in view of the emerging new understanding of a more complex miRNA biogenesis in plants, current tools may fail to characterise organism-specific and heterogeneous miRNA populations. RESULTS: miRA is a new tool to identify miRNA precursors in plants, allowing for heterogeneous and complex precursor populations. miRA requires small RNA sequencing data and a corresponding reference genome, and evaluates precursor secondary structures and precursor processing accuracy; key parameters can be adapted based on the specific organism under investigation. We show that miRA outperforms the currently best plant miRNA prediction tools both in sensitivity and specificity, for data involving Arabidopsis thaliana and the Volvocine algae Chlamydomonas reinhardtii; the latter organism has been shown to exhibit a heterogeneous and complex precursor population with little cross-species miRNA sequence conservation, and therefore constitutes an ideal model organism. Furthermore we identify novel miRNAs in the Chlamydomonas-related organism Volvox carteri. CONCLUSIONS: We propose miRA, a new plant miRNA identification tool that is well adapted to complex precursor populations. miRA is particularly suited for organisms with no existing miRNA annotation, or without a known related organism with well characterized miRNAs. Moreover, miRA has proven its ability to identify species-specific miRNAs. miRA is flexible in its parameter settings, and produces user-friendly output files in various formats (pdf, csv, genome-browser-suitable annotation files, etc.). It is freely available at https://github.com/mhuttner/miRA .The authors acknowledge funding from the Deutsche Forschungsgemeinschaft (SFB 960), the Bavarian Genome Research Network (BayGene), and the Bavarian Biosystems Network (BioSysNet)

Modelling aerated flows with smoothed particle hydrodynamics

Modelling aerated flows is a complex application of computational fluid dynamics (CFD) since the interfaces between air and water change rapidly. In this work, the simulation of aerated flows with the smoothed particle hydrodynamics (SPH) method is investigated with a focus towards the application in engineering practice. To prove the accuracy of the method, the processes of air entrainment and rising air bubbles are studied. Through monitoring the evolution of the bubble contours it is shown that the novel approach of adding artificial repulsion forces at the interface does not alter the dynamics but stabilizes the flow. Building on these fundamental processes we extend the discussion to practical applications with a special focus on forced aeration. Since the employment of a detailed SPH model to practical problems remains out of bounds due to the high computational demand, we propose a combined experimental and numerical study where experimental bubble characteristics are imposed on the numerical simulation. Based on the data of the conducted bubble column experiment, the computational demand is significantly decreased such that the oxygen consumption due to biokinetic processes can be modelled. The future perspective is to apply SPH to urban water systems, e.g., for simulating detailed processes in wastewater treatment and sewer hydraulics.(VLID)899117Version of recor

MATSim-T : Architecture and Simulation Times

Micro-simulations for transport planning are becoming increasingly important in traffic simulation, traffic analysis, and traffic forecasting. In the last decades the shift from using typically aggregated data to more detailed, individual based, complex data (e.g. GPS tracking) andthe continuously growing computer performance on fixed price level leads to the possibility of using microscopic models for large scale planning regions. This chapter presents such a micro-simulation. The work is part of the research project MATSim (Multi Agent Transport Simulation, http://matsim.org). In the chapter here the focus lies on design and implementation issues as well as on computational performance of different parts of the system. Based on a study of Swiss daily traffic – ca. 2.3 million individuals using motorized individual transport producing about 7.1 million trips, assigned to a Swiss network model with about 60,000 links, simulated and optimized completely time-dynamic for a complete workday – it is shown that the system is able to generate those traffic patterns in about 36 hours computation time