Central extensions of groups of sections

If q : P -> M is a principal K-bundle over the compact manifold M, then any invariant symmetric V-valued bilinear form on the Lie algebra k of K defines a Lie algebra extension of the gauge algebra by a space of bundle-valued 1-forms modulo exact forms. In the present paper we analyze the integrability of this extension to a Lie group extension for non-connected, possibly infinite-dimensional Lie groups K. If K has finitely many connected components we give a complete characterization of the integrable extensions. Our results on gauge groups are obtained by specialization of more general results on extensions of Lie groups of smooth sections of Lie group bundles. In this more general context we provide sufficient conditions for integrability in terms of data related only to the group K.Comment: 54 pages, revised version, to appear in Ann. Glob. Anal. Geo

Ultrastrong light-matter coupling at terahertz frequencies with split ring resonators and inter-Landau level transitions

We study strong light-matter coupling at terahertz frequencies employing a system based on an array of deeply subwavelength split ring resonators deposited on top of an ensemble of modulation-doped quantum wells. By applying a magnetic field parallel to the epitaxial growth axis, at low temperatures, Landau Levels are formed. We probe the interaction of the inter-Landau level transitions with the resonators modes, measuring a normalized coupling ratio Ωωc=0.58 between the inter-Landau level frequency ωc and the Rabi frequency Ω of the system. The physics of the system is studied as a function of the metasurface composition and of the number of quantum wells. We demonstrate that the light-matter coupling strength is basically independent from the metamaterial lattice spacing

A short purification process for quantitative isolation of PrP(Sc) from naturally occurring and experimental transmissible spongiform encephalopathies

BACKGROUND: Transmissible spongiform encephalopathies (TSEs) are neurodegenerative diseases affecting both humans and animals. They are associated with post-translational conversion of the normal cellular prion protein (PrP(C)) into a heat- and protease-resistant abnormal isoform (PrP(Sc)). Detection of PrP(Sc) in individuals is widely utilized for the diagnosis of prion diseases. METHODS: TSE brain tissue samples have been processed in order to quantitatively isolate PrP(Sc). The protocol includes an initial homogenization, digestion with proteinase K and salt precipitation. RESULTS: Here we show that over 97 percent of the PrP(Sc) present can be precipitated from infected brain material using this simple salting-out procedure for proteins. No chemically harsh conditions are used during the process in order to conserve the native quality of the isolated protein. CONCLUSION: The resulting PrP(Sc)-enriched preparation should provide a suitable substrate for analyzing the structure of the prion agent and for scavenging for other molecules with which it may associate. In comparison with most methods that exist today, the one described in this study is rapid, cost-effective and does not demand expensive laboratory equipment

Dengue-2 Structural Proteins Associate with Human Proteins to Produce a Coagulation and Innate Immune Response Biased Interactome

<p>Abstract</p> <p>Background</p> <p>Dengue virus infection is a public health threat to hundreds of millions of individuals in the tropical regions of the globe. Although Dengue infection usually manifests itself in its mildest, though often debilitating clinical form, dengue fever, life-threatening complications commonly arise in the form of hemorrhagic shock and encephalitis. The etiological basis for the virus-induced pathology in general, and the different clinical manifestations in particular, are not well understood. We reasoned that a detailed knowledge of the global biological processes affected by virus entry into a cell might help shed new light on this long-standing problem.</p> <p>Methods</p> <p>A bacterial two-hybrid screen using DENV2 structural proteins as bait was performed, and the results were used to feed a manually curated, global dengue-human protein interaction network. Gene ontology and pathway enrichment, along with network topology and microarray meta-analysis, were used to generate hypothesis regarding dengue disease biology.</p> <p>Results</p> <p>Combining bioinformatic tools with two-hybrid technology, we screened human cDNA libraries to catalogue proteins physically interacting with the DENV2 virus structural proteins, Env, cap and PrM. We identified 31 interacting human proteins representing distinct biological processes that are closely related to the major clinical diagnostic feature of dengue infection: haemostatic imbalance. In addition, we found dengue-binding human proteins involved with additional key aspects, previously described as fundamental for virus entry into cells and the innate immune response to infection. Construction of a DENV2-human global protein interaction network revealed interesting biological properties suggested by simple network topology analysis.</p> <p>Conclusions</p> <p>Our experimental strategy revealed that dengue structural proteins interact with human protein targets involved in the maintenance of blood coagulation and innate anti-viral response processes, and predicts that the interaction of dengue proteins with a proposed human protein interaction network produces a modified biological outcome that may be behind the hallmark pathologies of dengue infection.</p

Nominal Stability and Swiss Monetary Regimes Over Two Centuries

This paper documents nominal stability in Switzerland from 1805 to 2013 using a data set on annual price, wage and nominal GDP changes. The trends of these indicators are estimated by an unobserved-components stochastic-volatility model in order to control for short-term fluctuations and measurement error. Based on a narrative analysis of these trends five main findings emerge. (i) Fiat currency regimes in Switzerland provided a relatively stable monetary background even compared to the metal-currency regimes before WW1. (ii) The flexible inflation targeting regime adopted in December 1999 has performed best over the last two centuries measured by today's definition of nominal stability. (iii) Fiat currency regimes without clearly communicated nominal price anchor (Bretton Woods System and monetary targeting) were characterised by an inflation bias. (iv) The metal-currency regimes (competing currencies and bimetallism before World War 1, and to some extent flexible inflation targeting, were associated with a deflation bias. (v) Persistent deflations in terms of the CPI only occurred under metallic regimes before WW2. These episodes were accompanied by falling nominal GDP, falling employment but relatively stable hourly wages

Extraneural pathologic prion protein in sporadic Creutzfeldt-Jakob disease.

BACKGROUND: In patients with sporadic Creutzfeldt-Jakob disease, pathologic disease-associated prion protein (PrPSc) has been identified only in the central nervous system and olfactory-nerve tissue. Understanding the distribution of PrPSc in Creutzfeldt-Jakob disease is important for classification and diagnosis and perhaps even for prevention. METHODS: We used a highly sensitive method of detection--involving the concentration of PrPSc by differential precipitation with sodium phosphotungstic acid, which increased the sensitivity of Western blot analysis by up to three orders of magnitude--to search for PrPSc in extraneural organs of 36 patients with sporadic Creutzfeldt-Jakob disease who died between 1996 and 2002. RESULTS: PrPSc was present in the brain tissue of all patients. In addition, we found PrPSc in 10 of 28 spleen specimens and in 8 of 32 skeletal-muscle samples. Three patients had PrPSc in both spleen and muscle specimens. Patients with extraneural PrPSc had a significantly longer duration of disease and were more likely to have uncommon molecular variants of sporadic Creutzfeldt-Jakob disease than were patients without extraneural PrPSc. CONCLUSIONS: Using sensitive techniques, we identified extraneural deposition of PrPSc in spleen and muscle samples from approximately one third of patients who died with sporadic Creutzfeldt-Jakob disease. Extraneural PrPSc appears to correlate with a long duration of disease

Pioniergeist und Optimismus: Die Hetzer-Dachkonstruktion der Reithalle von St. Moritz

Am westlichen Ufer des St. Moritzersees steht an prominenter Lage ein unscheinbares Gebäude, das sich unter einer leicht vergilbten Haube aus Eternitplatten versteckt. Einzig das markante Walmdach, die Hauptfassade aus Lärchenschindeln und das mit Holzschnitzereien verzierte Eingangstor mit der Aufschrift «Manege» geben den heutigen Passanten einen Hinweis auf die frühere Bedeutung dieses Bauwerks und einem geübten Auge vielleicht sogar ein Indiz auf die besondere Konstruktionsweise, die sich darin verbirgt. Bei diesem Gebäude handelt es sich um die ab 1910 in der damals avantgardistischen Hetzerbauweise für den aufkommenden Pferdesport errichtete Reithalle, die heute als eidgenössisch schützenswertes Gebäude eingetragen ist. Bereits seit 2013 steht der nun fast 110-jährige Holzbau jedoch wegen Einsturzgefahr leer und kann nicht mehr für den Reitsport genutzt werden. Wie es so weit kommen konnte und warum der Erhalt der Reithalle höchste Priorität hat, soll im Folgenden in Bezug auf den historischen Kontext und die ingenieurtechnische Leistung aufgezeigt werden.ISSN:1011-6885ISSN:1011-668