4,397 research outputs found

    Significance of the Sm-Nd isotopic systematics of the Akilia Association

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    Samarium-Neodymium analyses were carried out on fourteen samples of basic to ultrabasic metavolcanics from several enclaves of the Amitsoq gneisses (T = to or approximately 3,700 Ma). Field observations suggest that all the analyzed rocks belong to the pre-Amitsoq Akilia Association. Consequently, a minimum age of 3,700 Ma is postulated for the emplacement of their protoliths. When all the data points are put together in a conventional isochron diagram, no clear isochron relationship can be discerned. However, the points seem to fall within a band broadly corresponding to an age of 3,600 Ma. The isotopic results are difficult to interpret satisfactorily. Two contrasting interpretations are offered and summarized: (1) data scatter as a result of open system behavior; and (2) data scatter due to a melange of data sets defining two distinct isochrons

    Crossover Between Universality Classes in the Statistics of Rare Events in Disordered Conductors

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    The crossover from orthogonal to the unitary universality classes in the distribution of the anomalously localized states (ALS) in two-dimensional disordered conductors is traced as a function of magnetic field. We demonstrate that the microscopic origin of the crossover is the change in the symmetry of the underlying disorder configurations, that are responsible for ALS. These disorder configurations are of weak magnitude (compared to the Fermi energy) and of small size (compared to the mean free path). We find their shape explicitly by means of the direct optimal fluctuation method.Comment: 7 pages including 2 figure

    First IBEX observations of the terrestrial plasma sheet and a possible disconnection event

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    The Interstellar Boundary Explorer (IBEX) mission has recently provided the first all-sky maps of energetic neutral atoms (ENAs) emitted from the edge of the heliosphere as well as the first observations of ENAs from the Moon and from the magnetosheath stagnation region at the nose of the magnetosphere. This study provides the first IBEX images of the ENA emissions from the nightside magnetosphere and plasma sheet. We show images from two IBEX orbits: one that displays typical plasma sheet emissions, which correlate reasonably well with a model magnetic field, and a second that shows a significant intensification that may indicate a near-Earth (similar to 10 R(E) behind the Earth) disconnection event. IBEX observations from similar to 0.5-6 keV indicate the simultaneous addition of both a hot (several keV) and colder (similar to 700 eV) component during the intensification; if IBEX directly observed magnetic reconnection in the magnetotail, the hot component may signify the plasma energization

    Entwicklung und Darstellung von Strategieoptionen zur Behandlung von Saatgut im ökologischen Landbau

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    Zur Erzeugung gesunden Saatgutes steht im Öko-Landbau neben präventiven Maßnahmen eine Reihe verschiedener Saatgutbehandlungsverfahren zur Verfügung (physikalische Methoden, Pflanzenextrakte, Naturstoffe und Mikroorganismenpräparate), die jedoch für die zahlreichen, wichtigen Wirt/Pathogen-Kombinationen nicht hinreichend untersucht waren. Inhalt und Ziel dieses Verbundvorhabens war es, Erfolg versprechende, aber hinsichtlich Handhabbarkeit und Wirksamkeit bislang nicht ausreichend untersuchte Varianten zu überprüfen sowie Schwellenwerte zu ermitteln, die eine Saatgutbehandlung indizieren. Um eine schnelle Übertragbarkeit wirksamer Verfahren in die Praxis zu ermöglichen, wurden neben den physikalischen Verfahren überwiegend gelistete Pflanzenstärkungsmittel untersucht. Im ersten Untersuchungsschritt wurden Klimakammer- und Gewächshausversuche angelegt. Ansätze, die sich unter diesen Modellbedingungen für die Praxistestung als geeignet erwiesen, wurden in Feldversuchen (Projekt 03OE127/2) überprüft. Für wichtige Wirt/Pathogen-Kombinationen konnten unter Modellbedingungen Behandlungsvarianten mit guten Wirkungen ausgewählt werden, die keine bis geringe negative Auswirkungen auf die Keimfähigkeit hatten. Bei Sommergerste mit Netzflecken oder Streifenkrankheit sowie bei Haferflugbrand konnten nach Behandlung mit Heißwasser, LEBERMOOSER, Ethanol, Milsana flüssig, Serenade und/oder Cedomon gute bis sehr gute Wirkungen erreicht werden. An Winterweizen mit Fusarium spp., Stagonospora nodorum bzw. Schneeschimmel sowie Winterroggen mit Schneeschimmel wurde eine Wirkung vor allem durch FZB 53, Warm- oder Heißwasserbehandlung und LEBERMOOSER erreicht. Von den besonders schwer zu bekämpfenden Krankheiten wurden Anthraknose an Lupine und Ascochyta pisi an Erbse mit Feuchtheißluft reduziert, jedoch war die Wirkung nicht ausreichend

    Ontogeny of synaptophysin and synaptoporin in the central nervous system

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    The expression of the synaptic vesicle antigens synaptophysin (SY) and synaptoporin (SO) was studied in the rat striatum, which contains a nearly homogeneous population of GABAergic neurons. In situ hybridization revealed high levels of SY transcripts in the striatal anlage from embryonic day (E) 14 until birth. In contrast. SO hybridization signals were low, and no immunoreactive cell bodies were detected at these stages of development. At E 14, SY-immunoreactivity was restricted to perikarya. In later prenatal stages of development SY-immunoreactivity appeared in puncta (identified as terminals containing immunostained synaptic vesicles), fibers, thick fiber bundles and ‘patches’. In postnatal and adult animals, perikarya of striatal neurons exhibited immunoreaction for SO; ultrastructurally SO antigen was found in the Golgi apparatus and in multivesicular bodies. SO-positive boutons were rare in the striatum. In the neuropil, numerous presynaptic terminals positive for SY were observed. Our data indicate that the expression of synaptic vesicle proteins in GABAergic neurons of the striatum is developmentally regulated. Whereas SY is prevalent during embryonic development, SO is the major synaptic vesicle antigen expressed postnatally by striatal neurons which project to the globus pallidus and the substantia nigra. In contrast synapses of striatal afferents (predominantly from cortex, thalamus and substantia nigra) contain SY

    Instantons and Monopoles in General Abelian Gauges

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    A relation between the total instanton number and the quantum-numbers of magnetic monopoles that arise in general Abelian gauges in SU(2) Yang-Mills theory is established. The instanton number is expressed as the sum of the `twists' of all monopoles, where the twist is related to a generalized Hopf invariant. The origin of a stronger relation between instantons and monopoles in the Polyakov gauge is discussed.Comment: 28 pages, 8 figures; comments added to put work into proper contex

    The scaling dimension of low lying Dirac eigenmodes and of the topological charge density

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    As a quantitative measure of localization, the inverse participation ratio of low lying Dirac eigenmodes and topological charge density is calculated on quenched lattices over a wide range of lattice spacings and volumes. Since different topological objects (instantons, vortices, monopoles, and artifacts) have different co-dimension, scaling analysis provides information on the amount of each present and their correlation with the localization of low lying eigenmodes.Comment: Lattice2004(topology), Fermilab, June 21 - 26, 2004; 3 pages, 3 figure

    Bimodal release ondansetron for acute gastroenteritis among adolescents and adults: A randomized clinical trial

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    Importance: Vomiting resulting from acute gastroenteritis is commonly treated with intravenous antiemetics in acute care settings. If oral treatment were beneficial, patients might not need intravenous administered hydration or medication. Furthermore, a long-acting treatment could provide sustained relief from nausea and vomiting. Objective: To determine whether an experimental long-acting bimodal release ondansetron tablet decreases gastroenteritis-related vomiting and eliminates the need for intravenous therapy for 24 hours after administration. Design, Setting, and Participants: This placebo-controlled, double-blind, randomized clinical trial included patients from 19 emergency departments and 2 urgent care centers in the United States from December 8, 2014, to February 17, 2017. Patients 12 years and older with at least 2 vomiting episodes from presumed gastroenteritis in the previous 4 hours and symptoms with less than 36 hours\u27 duration were randomized using a 3:2 active to placebo ratio. Analyses were performed on an intent-to-treat basis and conducted from June 1, 2017, to November 1, 2017. Intervention: Bimodal release ondansetron tablet containing 6 mg of immediate release ondansetron and 18 mg of a 24-hour release matrix for a total of 24 mg of ondansetron. Main Outcomes and Measures: Treatment success was defined as no further vomiting, no need for rescue medication, and no intravenous hydration for 24 hours after bimodal release ondansetron administration. Results: Analysis included 321 patients (mean [SD] age, 29.0 [11.1] years; 195 [60.7%] women), with 192 patients in the bimodal release ondansetron group and 129 patients in the placebo group. Treatment successes were observed in 126 patients in the bimodal release ondansetron group (65.6%) compared with 70 patients in the placebo group (54.3%), with an 11.4% (95% CI, 0.3%-22.4%) absolute probability difference. The proportion of treatment success was 21% higher among patients who received bimodal release ondansetron compared with those who received a placebo (relative risk, 1.21; 95% CI, 1.00-1.46; P = .04). In an analysis including only patients with a discharge diagnosis of acute gastroenteritis and no major protocol violations, there were 123 treatment successes (69.5%) in the bimodal release ondansetron group compared with 67 treatment successes (54.9%) in the placebo group (relative risk, 1.27; 95% CI, 1.05-1.53; P = .01). Adverse effects were infrequent and similar to the known safety profile of ondansetron. Conclusions and Relevance: This randomized clinical trial found that a long-acting bimodal release oral ondansetron tablet was an effective antiemetic among adolescents and adults with moderate to severe vomiting from acute gastroenteritis. The drug benefits extended to 24 hours after administration. Bimodal release ondansetron may decrease the need for intravenous access and emergency department care to manage acute gastroenteritis. Trial Registration: ClinicalTrials.gov identifier: NCT02246439

    Vergleichende Untersuchungen zur Regulierung des Kartoffelkäfers (Leptinotarsa decemlineata Say) mit Pyrethrum/Rapsöl-, Neemöl- und Bacillus thuringiensis-Präparaten

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    The Colorado Potato Beetle is one of the most important pests of potatoes. The effect of various plant protection products with neem oil (NeemAzal-T/S), pyrethrum/rape oil (Spruzit Neu) and Bacillus thuringiensis-B.t.t.(Novodor Neu) against this pest was compared in a field experiment 2004. Neem oil and B.t.t. reduced the number of Colorado Potato Beetle larvae as well as the losses of plant material due to feeding by beetle larvae significantly in the same way. Beneficial arthropods were not affected. The application of pyrethrum/rape oil has shown in this experiment no significant effect to reduce the number of Colorado Potato Beetles. However, the number of beneficial arthropods was reduced from 2.2 individuals/plant (untreated control) to 1.0 individual/plant

    k-strings and baryon vertices in SU(N) gauge theories

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    It is pointed out that the sine law for the k-string tension emerges as the critical threshold below which the spatial Z_N symmetry of the static baryon potential is spontaneously broken. This result applies not only to SU(N) gauge theories, but to any gauge system with stable k-strings admitting a baryon vertex made with N sources in the fundamental representation. Some simple examples are worked out.Comment: 4 pages, 4 figures, v2: reference added, v3: comments and references adde
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