Humboldt University of Berlin

About: Humboldt University of Berlin is a education organization based out in Berlin, Germany. It is known for research contribution in the topics: Population & Transplantation. The organization has 33671 authors who have published 61781 publications receiving 1908102 citations. The organization is also known as: Humboldt-Universität zu Berlin & Universitas Humboldtiana Berolinensis.

Electron reconstruction and identification efficiency measurements with the atlas detector using the 2011 lhc proton-proton collision data

Abstract: Many of the interesting physics processes to be measured at the LHC have a signature involving one or more isolated electrons. The electron reconstruction and identification efficiencies of the ATLAS detector at the LHC have been evaluated using proton-proton collision data collected in 2011 at TeV and corresponding to an integrated luminosity of 4.7 fb. Tag-and-probe methods using events with leptonic decays of and bosons and mesons are employed to benchmark these performance parameters. The combination of all measurements results in identification efficiencies determined with an accuracy at the few per mil level for electron transverse energy greater than 30 GeV.

Insects breathe discontinuously to avoid oxygen toxicity

Abstract: The respiratory organs of terrestrial insects consist of tracheal tubes with external spiracular valves that control gas exchange. Despite their relatively high metabolic rate, many insects have highly discontinuous patterns of gas exchange, including long periods when the spiracles are fully closed. Two explanations have previously been put forward to explain this behaviour: first, that this pattern serves to reduce respiratory water loss, and second, that the pattern may have initially evolved in underground insects as a way of dealing with hypoxic or hypercapnic conditions. Here we propose a third possible explanation based on the idea that oxygen is necessary for oxidative metabolism but also acts as a toxic chemical that can cause oxidative damage of tissues even at relatively low concentrations. At physiologically normal partial pressures of CO2, the rate of CO2 diffusion out of the insect respiratory system is slower than the rate of O2 entry; this leads to a build-up of intratracheal CO2. The spiracles must therefore be opened at intervals to rid the insect of accumulated CO2, a process that exposes the tissues to dangerously high levels of O2. We suggest that the cyclical pattern of open and closed spiracles observed in resting insects is a necessary consequence of the need to rid the respiratory system of accumulated CO2, followed by the need to reduce oxygen toxicity.

New horizons for managing the environment: A review of coupled social-ecological systems modeling

Abstract: Conventional approaches to natural resource management are increasingly challenged by environmental problems that are embedded in highly complex systems with profound uncertainties. These so-called social-ecological systems (SESs) are characterized by strong links between the social and the ecological system and multiple interactions across spatial and temporal scales. New approaches are needed to manage those tightly coupled systems; however, basic understanding of their nonlinear behavior is still missing. Modeling is a traditional tool in natural resource management to study complex, dynamic systems. There is a long tradition of SES modeling, but the approach is now being more widely recognized in other fields, such as ecological and economic modeling, where issues such as nonlinear ecological dynamics and complex human decision making are receiving more attention. SES modeling is maturing as a discipline in its own right, incorporating ideas from other interdisciplinary fields such as resilience or complex systems research. In this paper, we provide an overview of the emergence and state of the art of this cross-cutting field. Our analysis reveals the substantial potential of SES models to address issues that are of utmost importance for managing complex human-environment relationships, such as: (i) the implications of ecological and social structure for resource management, (ii) uncertainty in natural and social systems and ways to address it, (iii) the role of coevolutionary processes in the dynamics of SESs, and (iv) the implications of microscale human decision making for sustainable resource management and conservation. The complexity of SESs and the lack of a common analytical framework, however, also pose significant challenges for this emerging field. There are clear research needs with respect to: (i) approaches that go beyond rather simple specifications of human decision making, (ii) development of coping strategies to deal with (irreducible) uncertainties, (iii) more explicit modeling of feedbacks between the social and ecological systems, and (iv) a conceptual and methodological framework for analyzing and modeling SESs. We provide ideas for tackling some of these challenges and indicate potential key focal areas for SES modeling in the future.

Up-regulation of monocytic IL-10 by tumor necrosis factor-α and cAMP elevating drugs

Abstract: It is well established that endotoxin [lipopolysacharide (LPS)] induces pro-inflammatory cytokine production in monocytes, which is followed by secretion of the anti-inflammatory cytokine, IL-10. IL-10 down-regulates inflammatory response [tumor necrosis factor (TNF)-alpha, IL-1, IL-6, IL-8] as well as IL-10 synthesis itself. We wondered whether pro-inflammatory cytokines such as TNF-alpha may be involved in the regulation of human IL-10 synthesis. TNF-alpha induced de novo IL-10 mRNA expression in a dose-dependent manner but no IL-10 protein in human peripheral blood mononuclear cells. Furthermore, LPS-induced IL-10 gene and protein expression was significantly inhibited by neutralizing anti-TNF-alpha mAb. On the basis of these results, we conclude that TNF-alpha is involved in the up-regulation of its antagonist IL-10. Paradoxically, drugs that effectively inhibit expression of TNF-alpha via the elevation of intracellular cAMP level (iloprost, pentoxifylline, prostaglandin E2 and N6,2-O-dibutyryl cAMP) augmented the endotoxin-induced IL-10 synthesis at both protein and mRNA levels. In order to provide a basis for the analysis of the transcriptional regulation of the human IL-10 gene, we isolated a fragment of the human IL-10 gene containing 1308 bp of the 5' non-coding sequence. It shows remarkable homology to the mouse IL-10 promoter in regions that have been associated with transcriptional regulation, including a cAMP responsive element which could explain the cAMP-mediated effects. The lack of a NF-kappa B-like binding site in the human sequence suggests a NF-kappa B-independent mechanism of TNF-alpha-induced IL-10 gene activation.(ABSTRACT TRUNCATED AT 250 WORDS)