1,914 research outputs found

    Large violation of Bell inequalities with low entanglement

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    In this paper we obtain violations of general bipartite Bell inequalities of order nlog⁥n\frac{\sqrt{n}}{\log n} with nn inputs, nn outputs and nn-dimensional Hilbert spaces. Moreover, we construct explicitly, up to a random choice of signs, all the elements involved in such violations: the coefficients of the Bell inequalities, POVMs measurements and quantum states. Analyzing this construction we find that, even though entanglement is necessary to obtain violation of Bell inequalities, the Entropy of entanglement of the underlying state is essentially irrelevant in obtaining large violation. We also indicate why the maximally entangled state is a rather poor candidate in producing large violations with arbitrary coefficients. However, we also show that for Bell inequalities with positive coefficients (in particular, games) the maximally entangled state achieves the largest violation up to a logarithmic factor.Comment: Reference [16] added. Some typos correcte

    Kupferersatz im ökologischen Weinbau: Entwicklung und Anwendung neuer Formulierungs- und Produktionstechnologien fĂŒr den praxisgerechten Einsatz bakterieller Antagonisten

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    Im vorliegenden Projekt wurde der Einsatz bakterieller Antagonisten als Kupferersatz zur BekĂ€mpfung von Plasmopara viticola, dem Erreger des Falschen Mehltaus der Weinrebe, im ökologischen Weinbau optimiert. Mit Hilfe von Dual-Kultur-Tests wurden sechs bakterielle Antagonisten aus vorhandenen Antagonisten-Stammsammlungen selektiert (Testpilze: Pythium ultimum; Phytophthora infestans). Mittels Blattscheiben-Test im Labor konnte mit den ausgewĂ€hlten Isolaten eine Befallsreduzierung auf unter 5 % BefallsstĂ€rke erzielt werden. Der Befall in der unbehandelten Kontrolle schwankte je nach Ansatz zwischen 19 % und 35 %. Unter GewĂ€chshausbedingungen zeigte sich an Topfreben ebenfalls eine gute biologische Wirksamkeit gegen den Schadpilz. Die Kontrollpflanzen wiesen einen Befall zwischen 60 % und 77 % BefallsstĂ€rke auf, wĂ€hrend die BlĂ€tter der PrĂŒfglieder weniger als 5 % BefallsstĂ€rke zeigten. Zur Eliminierung des Kupferanteils wurden fĂŒr die Freilandversuche drei hochwirksame Isolate ausgewĂ€hlt und in die BekĂ€mpfungsstrategie „Öko-Standard“ integriert. Die Isolate gehörten den Bakteriengattungen Pseudomonas spp. und Bacillus spp. an. Um die Wirksamkeit im Freiland zu steigern, wurden Formulierungshilfsstoffe ausgewĂ€hlt, die den Bakterien kurz vor der Applikation zugesetzt wurden. Dabei fanden die Substanzen Xanthan gum, Trehalose und PHYTO-VITALÂź Anwendung. Aufgrund des extremen Sommers im Jahr 2003 war der Peronospora-Befall im Weinberg so gering, dass keine aussagekrĂ€ftigen Ergebnisse zum Einsatz unter Freilandbedingungen gemacht werden konnten. Studien zur Etablierung der Antagonisten auf dem Rebblatt haben gezeigt, dass die BlĂ€tter der bakterienbehandelten Versuchsglieder Bakteriendichten aufwiesen, die um etwa eine Zehnerpotenz höher lagen als die mit Kupfer behandelten BlĂ€tter. Um mögliche GĂ€rbeeinflussungen zu erfassen, wurden die Moste im Kleinmaßstab (25-Liter GĂ€rbehĂ€lter) vergoren. Bisher zeigten sich keine Abweichungen vom kupferhaltigen Versuchsglied „Öko-Standard“

    Hypercontractivity on the qq-Araki-Woods algebras

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    Extending a work of Carlen and Lieb, Biane has obtained the optimal hypercontractivity of the qq-Ornstein-Uhlenbeck semigroup on the qq-deformation of the free group algebra. In this note, we look for an extension of this result to the type III situation, that is for the qq-Araki-Woods algebras. We show that hypercontractivity from LpL^p to L2L^2 can occur if and only if the generator of the deformation is bounded.Comment: 17 page

    Connes' embedding problem and Tsirelson's problem

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    We show that Tsirelson's problem concerning the set of quantum correlations and Connes' embedding problem on finite approximations in von Neumann algebras (known to be equivalent to Kirchberg's QWEP conjecture) are essentially equivalent. Specifically, Tsirelson's problem asks whether the set of bipartite quantum correlations generated between tensor product separated systems is the same as the set of correlations between commuting C*-algebras. Connes' embedding problem asks whether any separable II1_1 factor is a subfactor of the ultrapower of the hyperfinite II1_1 factor. We show that an affirmative answer to Connes' question implies a positive answer to Tsirelson's. Conversely, a positve answer to a matrix valued version of Tsirelson's problem implies a positive one to Connes' problem

    Joint system quantum descriptions arising from local quantumness

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    Bipartite correlations generated by non-signalling physical systems that admit a finite-dimensional local quantum description cannot exceed the quantum limits, i.e., they can always be interpreted as distant measurements of a bipartite quantum state. Here we consider the effect of dropping the assumption of finite dimensionality. Remarkably, we find that the same result holds provided that we relax the tensor structure of space-like separated measurements to mere commutativity. We argue why an extension of this result to tensor representations seems unlikely

    Mineralogy and mineral chemistry of detrital platinum-group minerals and gold particles from the Elbe, Germany

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    In heavy mineral concentrates of the Elbe, gold and platinum-group minerals (PGMs) are observed. Two fractions (&gt; 63 and &lt; 63 ”m) of the concentrate are analyzed by reflected-light microscopy, scanning electron microscopy with automated mineralogy software and electron microprobe analysis (EPMA). Other heavy minerals are cassiterite, ferberite, monazite, uraninite, columbite–tantalite, magnetite, zircon and cinnabar. Scanning electron microscopy determined the modal abundance of PGMs, gold and the other heavy minerals. The PGMs are mainly Os–Ir–Ru–(Pt) alloys, Pt–Fe alloys, sperrylite and rustenburgite. Compositional variation of PGMs and gold was analyzed by EPMA. This showed that Pt–Fe alloys are (1) native platinum (&gt; 80 atom %), (2) ferroan Pt (20 atom % to 50 atom % Fe), (3) isoferroplatinum (2.64 to 3.04 apfu of sum PGE, platinum-group element), (4) tetraferroplatinum group with Ni + Cu + Fe ≈ 50 atom %, and (5) Îł(Pt,Fe) with sum PGE &gt; 3.04 apfu. The Os–Ir–Ru–(Pt) alloys show large compositional variations. Platinum and Fe enrichment is typically observed for Ir-rich Os–Ir–Ru alloys. Gold particles often show compositional zoning of Ag-rich cores and Ag-poor rims due to selective leaching of Ag. Similarly, Hg-rich rims of gold particles are analyzed. These are interpreted as the results of in situ amalgamation due to mobilization of Hg from the associated cinnabar particles. The size and shape of the gold particles generally argue for short transportation distances. Similarly, almost euhedral sperrylite and Pt–Fe alloys suggest a source region close to the sampling site. However, roundish Os–Ir–Ru–(Pt) alloys presumably have experienced longer transportation in the river. Gabbroic dikes of the Lusatia block contain sperrylite and gold particles, which can be the source for these particles found in the concentrate. The composition of the Os–Ir–Ru–(Pt) alloys is similar to previous studies on the Vestƙev placer in Czech Republic. Both locations are within the drainage area of the Elbe and can therefore be the source of the PGM and gold particles in the concentrate.</p

    The development of a natural plankton population in an outdoor tank with nutrient-poor sea water. II. Changes in dissolved carbohydrates and amino acids

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    terrelations between plankton communities and dissolved carbohydrates and amino acids were investigated under near-natural conditions in sea water enclosed in plastic tanks. In summer 1972 the development of a natural plankton population was followed in a 3-m3 plastic tank for 28 d. In the course of this experiment, concentrations of dissolved neutral carbohydrates and free amino acids were determined. Results are in the range of published data for the open sea with respect to concentrations (0.2-2.5 pnoles dm-3 total sugar; 0.2-3.1 pnoles dm3 total amino acids) and qualitative composition. A plankton succession was observed during the experiment; this was accompanied by distinct alterations in the concentrations of dissolved amino acids and carbohydrates. Glucose and lysine occurred in highest concentrations. Maximum rate of increase was 29 nmoles dm3 h-' for glucose, and 25 nmoles dm3 h-' for lysine. The rates of decrease are in the same range as bacterial uptake rates determined by various authors employing tracer methods. Numerous positive, highly significant correlations suggest heteropoly- saccharides as one source of individual carbohydrates. Relations between certain species within the plankton succession and occurrence of dissolved organic substances were observed. Significant positive correlations existed between glucose and diatoms as well as between glucose, galactose, mannose, arabinose and ribose and phytoplankton biomass. There were also several significant positive correlations of amino acids, especially of valine, leucine and isoleucine with other biological parameters

    Extended Distal Pancreatectomy with En Bloc Resection of the Celiac Axis for Locally Advanced Pancreatic Cancer: A Case Report and Review of the Literature

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    Due to a lack of early symptoms, pancreatic cancers of the body and tail are discovered mostly at advanced stages. These locally advanced cancers often involve the celiac axis or the common hepatic artery and are therefore declared unresectable. The extended distal pancreatectomy with en bloc resection of the celiac artery may offer a chance of complete resection. We present the case of a 48-year-old female with pancreatic body cancer invading the celiac axis. The patient underwent laparoscopy to exclude hepatic and peritoneal metastasis. Subsequently, a selective embolization of the common hepatic artery was performed to enlarge arterial flow to the hepatobiliary system and the stomach via the pancreatoduodenal arcades from the superior mesenteric artery. Fifteen days after embolization, the extended distal pancreatectomy with splenectomy and en bloc resection of the celiac axis was carried out. The postoperative course was uneventful, and complete tumor resection was achieved. This case report and a review of the literature show the feasibility and safety of the extended distal pancreatectomy with en bloc resection of the celiac axis. A preoperative embolization of the celiac axis may avoid ischemia-related complications of the stomach or the liver
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