2,245 research outputs found

    Eternity and the cosmological constant

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    The purpose of this paper is to analyze the stability of interacting matter in the presence of a cosmological constant. Using an approach based on the heat equation, no imaginary part is found for the effective potential in the presence of a fixed background, which is the n-dimensional sphere or else an analytical continuation thereof, which is explored in some detail.Comment: 45 pages, 6 figure

    Food Security: A Conceptual Analysis of Linkages and Interests in UNCED Negotiations

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    Environmental and developmental concerns on the United Nations Conference on Environment and Development (UNCED) agenda are closely interrelated, both from substantive and procedural vantages. Food security, one of the proposed global goals of UNCED, is a concrete example of these concerns. This study explores practical applications of disaggregating issue complexity and explores a more formal way to improve understanding of how parties to the negotiation move toward mutually acceptable outcomes. Beginning with a broad framework, conceptual space, we identify six dimensions within which parties define a challenge like food security, their interests, and their beliefs about what should be done. Countries draw implications about the various levels of linkages within a particular issue area. At the same time that countries are defining the salience of an issue for themselves, they are also formulating judgments about possible policy responses to address the problems. These judgments are grounded in traditions of ethics and political philosophy, but manifest themselves as preferences among policies. Over the course of a negotiation, changes occur in perceptions, knowledge, and the relative importance assigned to corresponding problem and response attributes. Decision analysis models are well-suited to structuring this type of movement, and thus may assist delegates, conference leaders, and mediators while negotiations are still in progress

    Disk winds of B[e] supergiants

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    The class of B[e] supergiants is characterized by a two-component stellar wind consisting of a normal hot star wind in the polar zone and a slow and dense disk-like wind in the equatorial region. The properties of the disk wind are discussed using satellite UV spectra of stars seen edge-on, i.e. through the equatorial disk. These observations show that the disk winds are extremely slow, 50-90 km/s, i.e. a factor of about 10 slower than expected from the spectral types. Optical emission lines provide a further means to study the disk wind. This is discussed for line profiles of forbidden lines formed in the disk.Comment: 7 pages, LaTeX, 3 ps figures, uses lamuphys.sty from Springer-Verlag, to be published in the proceedings of IAU Coll. 169 "Variable and Non-spherical Stellar Winds in Luminous Hot Stars" held in Heidelberg 199

    Estimating homelessness in the Netherlands using a capture-recapture approach

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    This study focuses on the homeless population in the Netherlands, as an indicator of social exclusion. By applying the capture-recapture (CRC) methodology to three registers, not only the size of the homeless population could be estimated, but also its composition in terms of gender, age, place of living, and origin could be depicted. Because of the use of three registers and the availability of background characteristics for each of the registers, the usual stringent assumptions of capture recapture methodology is circumvented. This advanced application of CRC to estimate the homeless population on the national level, has led to official figures for five subsequent reference dates (January 1st of 2009, 2010, 2011, 2012 and 2013). In 2009 the size of the total homeless population in the Netherlands was estimated at 17,767, of which 5169 were registered on one of the three lists. Between 2009 and 2012 the estimated size of the population increased, which was largely due to the financial crisis. For all reference dates, the composition of this population showed that generally more men than women were registered and that homeless people in the age category of 30–49 years old were registered more than the younger or older age groups. Compared to the general Dutch population, the homeless population includes relatively many men, many people aged 30–49 years and people with a non-western backgroun

    Synthesis and post-synthetic modification of amine-, alkyne-, azide- and nitro-functionalized metal-organic frameworks based on DUT-5

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    Functionalized 4,4â€Č-biphenyldicarboxylic acid molecules with additional amine, alkyne, azide or nitro groups were prepared and applied in the synthesis of novel metal-organic frameworks and mixed-linker metal-organic frameworks isoreticular to DUT-5. The properties of the frameworks could be tuned by varying the number of functional groups in the materials and the amine groups were employed in post-synthetic modification reactions without changing the framework structure or significantly decreasing the porosity of the materials. © The Royal Society of Chemistry 2015

    Up-regulation of the anti-inflammatory adipokine adiponectin in acute liver failure in mice

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    BACKGROUND/AIMS: Recent reports suggest that the adipose tissue and adipokines are potent modulators of inflammation. However, there is only scarce knowledge on the functional role and regulation of endogenous adiponectin in non-fat tissues such as the liver under conditions of acute inflammation. METHODS: In the present study, we investigated adiponectin expression in healthy murine liver tissue and under inflammatory conditions in vivo. RESULTS: Adiponectin mRNA was readily detectable in healthy liver tissue and further increased in ConA-mediated acute liver failure. Adiponectin protein expression was mainly found in hepatic endothelial cells. In vitro adiponectin mRNA expression was detectable in several cell types, including primary hepatic sinusoidal endothelial cells, stellate cells, and macrophages. Mice pretreated with adiponectin before ConA administration developed reduced hepatic injury as shown by decreased release of transaminases and reduced hepatocellular apoptotis. Of note, TNF-alpha levels were not affected by adiponectin, whereas IL-10 production was increased. Neutralisation of IL-10 diminished the protective effect of adiponectin. CONCLUSIONS: Adiponectin expression is up-regulated in ConA-mediated acute liver failure. Therefore, adiponectin might play a role in the control and limitation of inflammation in the liver. Moreover, our data suggest a role for IL-10 in adiponectin-mediated hepatoprotection

    Low subjective social status in the police is linked to health-relevant changes in diurnal salivary alpha-amylase activity in Swiss police officers.

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    The objective of this study was to assess basal autonomic nervous system (ANS) activity as a pathway linking subjective social status to health in a high-demand work environment. It was hypothesized that officers with a lower status experienced more chronic stress (higher basal ANS activity) and that chronic stress was related to more health problems. Fifty-six male and female Swiss police officers self-reported on subjective social status (country, community, friends, police) and their health (depression, post-traumatic stress, physical symptoms) and collected 12 saliva samples over two days for basal α-amylase activation (sAA) assessment. Multilevel regression analyses revealed that subjective social status in the police and physical symptoms explained a significant part of the variance in diurnal sAA activity patterns. The current findings support the idea that more narrowly defined subjective social status may be more closely linked to biological stress mechanisms. Additionally, sAA activity was specifically related to physical, but not mental health problems. These results suggest that subjective social status referencing one's work environment may be a promising early indicator of health-relevant changes in stress-related physiological systems

    Mobility of the SecA 2-helix-finger is not essential for polypeptide translocation via the SecYEG complex

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    The bacterial ATPase SecA and protein channel complex SecYEG form the core of an essential protein translocation machinery. The nature of the conformational changes induced by each stage of the hydrolytic cycle of ATP and how they are coupled to protein translocation are not well understood. The structure of the SecA–SecYEG complex revealed a 2-helix-finger (2HF) of SecA in an ideal position to contact the substrate protein and push it through the membrane. Surprisingly, immobilization of this finger at the edge of the protein channel had no effect on translocation, whereas its imposition inside the channel blocked transport. This analysis resolves the stoichiometry of the active complex, demonstrating that after the initiation process translocation requires only one copy each of SecA and SecYEG. The results also have important implications on the mechanism of energy transduction and the power stroke driving transport. Evidently, the 2HF is not a highly mobile transducing element of polypeptide translocation

    Entangling power and operator entanglement in qudit systems

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    We establish the entangling power of a unitary operator on a general finite-dimensional bipartite quantum system with and without ancillas, and give relations between the entangling power based on the von Neumann entropy and the entangling power based on the linear entropy. Significantly, we demonstrate that the entangling power of a general controlled unitary operator acting on two equal-dimensional qudits is proportional to the corresponding operator entanglement if linear entropy is adopted as the quantity representing the degree of entanglement. We discuss the entangling power and operator entanglement of three representative quantum gates on qudits: the SUM, double SUM, and SWAP gates.Comment: 8 pages, 1 figure. Version 3: Figure was improved and the MS was a bit shortene

    Dataset on the activation of Mueller cells through macrophages upon hypoxia in the retina

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    The dataset presented in this article complements the article entitled "Myeloid cells contribute indirectly to VEGF expression upon hypoxia via activation of Mueller cells" (C. Nuernberg, N. Kociok, C. Brockmann, T. Lischke, S. Crespo-Garcia, N. Reichhart, S. Wolf, R. Baumgrass, S.A. Eming, S. Beer-Hammer, and A.M. Joussen). This complementary dataset provides further insight into the experimental validation of the VEGF(fl/fl) LysMCre (here named VEGF(mcko)) knockout model used in the main article through genomic and quantitative Real-Time PCR in various murine tissues as well as additional flow cytometry data and immunohistochemical stainings. By providing these data, we aim to enable researcher to reproduce and critically analyze our data
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