2,514 research outputs found

    Cauchy Problem and Green's Functions for First Order Differential Operators and Algebraic Quantization

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    Existence and uniqueness of advanced and retarded fundamental solutions (Green's functions) and of global solutions to the Cauchy problem is proved for a general class of first order linear differential operators on vector bundles over globally hyperbolic Lorentzian manifolds. This is a core ingredient to CAR-/CCR-algebraic constructions of quantum field theories on curved spacetimes, particularly for higher spin field equations.Comment: revised version: typos; reordering of sec 2; results unchange

    Schöne böse Töne : eine Unterrichtseinheit zum Hexenzauber in Giuseppe Verdis Oper „Macbeth“

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    Wie fühlt man sich als Hexe? Welche Gesten sind typisch für einen Mörder? Mit Hilfe der Szenischen Interpretation lernen die SchülerInnen Verdis Macbeth aus einem ganz subjektiven Blickwinkel kennen

    Phase diagram and surface tension in the three-flavor Polyakov-quark-meson model

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    We obtain the in-medium effective potential of the three-flavor Polyakov-Quark-Meson model as a real function of real variables in the Polyakov loop variable, to allow for the study of all possible minima of the model. At finite quark chemical potential, the real and imaginary parts of the effective potential, in terms of the Polyakov loop variables, are made apparent, showing explicitly the fermion sign problem of the theory. The phase diagram and other equilibrium observables, obtained from the real part of the effective potential, are calculated in the mean-field approximation. The obtained results are compared to those found with the so-called saddle-point approach. Our procedure also allows the calculation of the surface tension between the chirally broken and confined phase, and the chirally restored and deconfined phase. The values of surface tension we find for low temperatures are very close to the ones recently found for two-flavor chiral models. Some consequences of our results for the early Universe, for heavy-ion collisions, and for proto-neutron stars are briefly discussed.Comment: 17 pages, 6 figures. V2: typos fixed, references adde

    (Orpheus wendet sich um) : szenisch-musikalische Interpretation der drei Orpheus-Opern

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    So wie sich Orpheus im Hades umwendet, weil er sich versichern will, dass seine Eurydike noch hinter ihm ist, so muss sich heute die Musikpädagogik immer wieder umwenden, um sich zu vergewissern, dass die SchülerInnen ihr folgen. Während Orpheus jedoch die Gattin zum zweiten Mal verliert, besteht im Unterricht die Chance, durch neue Methoden das Interesse für Musik zu stärken. Die Szenische Interpretation von Musiktheater gibt dem „Musiklehrerstand“ die Möglichkeit, durch spielerische Motivation einen Zugang zu den Werken zu schaffen, der eine Zeit lang die „Not und Plage“ der Schule vergessen lässt. SchülerInnen und LehrerInnen verhalten sich anders im Umgang miteinander, werden zu SpielerInnen und SpielleiterInnen, die gemeinsam eine Interpretation der Werke erarbeiten. Wir haben das vorliegende Konzept in verschiedenen SchülerInnen-, StudentInnen- und LehrerInnengruppen durchgeführt - „ein halbes Dutzend Lektionen“ -, bis wir zu dieser Version gekommen sind. Allen Beteiligten gilt unser Dank, besonders den SchülerInnen der Klasse 10a des Goethe-Gymnasiums in Berlin Wilmersdorf und deren Musiklehrer Gero Krüger. In dieser Klasse sind die Fotos entstanden und viele Anregungen der SchülerInnen waren wichtig für die Überarbeitung einzelner Spielverfahren. Die Auseinandersetzung mit der Thematik kann schon in der 8. oder 9. Klasse beginnen, je nach Reifegrad der SchülerInnen. In der Oberstufe bietet es sich dann an, einzelne Themen zu vertiefen oder musikalische Analysen im Anschluss an die Methoden zu erarbeiten

    Vom Gestus zur Struktur : szenische Interpretation von "Moses und Aron"

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    Die beiden vorgestellten Szenen sind einem Gesamtkonzept zur szenischen Interpretation von „Moses und Aron“ entnommen. Sie zeigen, wie eine historische Re-Konstruktion musikpraktisch stattfindet durch De-Konstruktion der Partitur und Rückführung eines religionsphilosophischen Textes auf den realistischen Gehalt der „Story“. Interessanterweise haben die bisherigen Erfahrungen mit Schüler/innen gezeigt, dass diese realistische Wende der Schönbergschen Oper bei den Jugendlichen lebhafte „existentielle“ Debatten auslöst: Was heißt „Gottesidee“, was bedeutet „auserwählt“, was ist eine „revolutionäre Ideologie“ und - last but not least - warum haben die afroamerikanischen Sklaven „Go down Moses“ gesungen“? Die beiden hier vorgestellten Szenen zeigen, wie auf dem Weg über Rolleneinfühlung sowie Geh- und Sprechhaltungen ein Zugang zu einer komplexen Partitur ermöglicht wird. Die szenische Interpretation führt durch die Auseinandersetzung mit dem Inhalt und nicht über Musiktheorie oder Intonationsübungen hin zu Zwölftonmusik und erschließt eine wirkungsvolle Partitur: vom Gestus zur Struktur

    The Effect of Pulling Out Cochlear Implant Electrodes on Inner Ear Microstructures: A Temporal Bone Study

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    The exchange of an cochlear implant or the re-positioning of an electrode have become more frequently required than a decade ago. The consequences of such procedures at a microstructural level within the cochlea are not known. It was the aim of the present study to further investigate the effects of an CI electrode pull-out. Therefore 10 freshly harvested temporal bones (TB) were histologically evaluated after a cochlear implant electrode pull-out of a perimodiolar electrode. In additional 9 TB the intrascalar movements of the CI electrode while being pulled-out were digitally analysed by video- capturing. Histologically, a disruption of the modiolar wall or the spiral osseous lamina were not observed. In one TB, a basilar membrane lifting up was found, but it could not be undoubtedly attributed to the pull-out of the electrode. When analyzing the temporal sequence of the electrode movement during the pull-out, the electrode turned in one case so that the tip elevates the basilar membrane. The pull- out of perimodiolarly placed CI electrodes does not damage the modiolar wall at a microstructural level and should be guided (e.g., forceps) to prevent a 90 o turning of the electrode tip into the direction of the basilar membrane

    Uptake of hydrophobic organic compounds, including OCPs and PBDEs, and perfluoroalkyl acids (PFAAs) in fish and blue crabs of the lower Passaic River (NJ, USA)

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    The bioavailability and bioaccumulation of sedimentary hydrophobic organic compounds (HOCs) is of concern at contaminated sites. Passive samplers have emerged as a promising tool to measure the bioavailability of sedimentary HOCs and possibly to estimate their bioaccumulation. We thus analyzed HOCs including organochlorine pesticides (OCPs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo‐p‐dioxins/furans (PCDD/Fs) in sediment, porewater and riverwater using low density polyethylene (LDPE) passive samplers, and in 11 different finfish species and blue crab from the lower Passaic River. Additionally, perfluorinated alkyl acids (PFAAs) were measured in grab water samples, sediment and fish. Best predictors of bioaccumulation in biota were either porewater concentrations (for PCBs and OCPs), or sediment organic carbon (PBDEs and PFAAs), including black carbon (OCPs, PCBs and some PCDD/F congeners) normalized concentrations. Measured lipid‐based concentrations of the majority of HOCs exceeded the chemicals\u27 activites in porewater by at least 2‐fold, suggesting dietary uptake. Trophic magnification factors were \u3e 1 for moderately hydrophobic analytes (log KOW = 6.5–8.2) with low metabolic transformation rates (\u3c 0.01 day−1), including longer alkyl chain PFAAs. For analytes with lower (4.5–6.5) and higher (\u3e8.2) KOWs, metabolic transformation was more important in reducing trophic magnification

    The semisolid bolus swallow test for clinical diagnosis of oropharyngeal dysphagia: a prospective randomised study

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    Contrary to clinical experience, clinical swallow tests are predominantly performed using water (water swallow tests, WST). In this study, we examine whether swallow tests performed using a bolus of semisolid food (bolus swallow test, BST) offer benefits. In a prospective, randomised, blind study, the results of a standardised saliva swallow test (SST), WST, BST, combinations of these tests and an endoscopic swallow test (FEES) in patients with oropharyngeal swallowing disorders of neurological (NEU) and non-neurological (NNEU) origin were compared. Sensitivity, specificity, test accuracy and inter-rater reliability were analysed. 62 patients (mean age = 64.68; range = 22–84) were included in the study (NEU = 40; NNEU = 22). A sensitivity of 70.7% (NEU = 70.3%, NNEU = 71.4%) and specificity of 82.5% (NEU = 92.3%; NNEU = 100%) were determined for the WST. The BST + SST was found to have a sensitivity of 89.6% (NEU = 66.7%; NNEU = 90.9%) and a specificity of 72.7% (NEU = 87.5%; NNEU = 90.9%). Analysis of test accuracy showed a statistically significant correlation between FEES and BST + SST. Only BST + SST exhibited statistically significant inter-rater reliability. BST in combination with SST was the sensitive clinical instrument for detecting aspiration both over the patient population as a whole and over the two sub-populations. Inter-rater reliability was found to be statistically significant. The results presented here demonstrate the benefit of semisolid food in investigating clinical dysphagia
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