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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 5411-5418 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We have successfully fabricated superconducting nanobridges and grain-boundary junctions from epitaxial YBa2Cu3O7−δ thin films with thickness between 20 and 30 nm and width down to ∼100 nm. The patterning process turned out to severely deteriorate the transport properties resulting in structural damage, corrosion, and oxygen loss. The most crucial steps are the baking procedure used to cure the electron beam resist, the resist development, and the ion beam etching process. By optimizing these steps and applying a suitable post-treatment procedure a significant enhancement of the sample quality could be achieved. An ultraviolet light assisted oxygenation procedure after the patterning process enabled us to achieve superconducting transition temperatures between 80 and 87 K and critical current densities at 4.2 K up to 4×107 A cm−2 for the nanobridges and 5×103–2×105 A cm−2 for the grain boundary junctions. At 4.2 K junctions with width down to 100 nm corresponding to a junction area down to 2.3×10−3 μm2 showed superconductivity. © 2002 American Institute of Physics.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 1095-1097 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We performed numerical simulations and experiments on Josephson vortex flow transistors based on parallel arrays of YBa2Cu3O7–δ grain boundary junctions with a cross gate line allowing us to operate the same devices in two different modes named the Josephson fluxon transistor (JFT) and Josephson fluxon–antifluxon transistor (JFAT). The simulations yield a general expression for the current gain versus number of junctions and normalized loop inductance and predict higher current gain for the JFAT. The experiments are in good agreement with simulations and show improved coupling between gate line and junctions for the JFAT as compared to the JFT. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3654-3656 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We report on the preparation and characterization of the double-perovskite compound Sr2CrWO6 with a Curie temperature of 390 K. We have fabricated both Sr2CrWO6 bulk sintered polycrystalline bars and high-quality epitaxial thin films on SrTiO3 substrates by pulsed-laser deposition. The samples were characterized by thermogravimetric analysis, x-ray diffraction, electrical transport, and magnetization measurements. Polycrystalline samples containing a large number of grain boundaries show a large low-field magnetoresistance of up to 100% at 5 K. At room temperature, this effect is reduced to a few percent. Our results show that Sr2CrWO6 is an interesting candidate for room-temperature magnetoelectronic materials. © 2001 American Institute of Physics.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Science, Ltd
    Journal of neurochemistry 80 (2002), S. 0 
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Clinical studies have shown that estrogen deprivation through menopause is a risk factor in both the initiation and progression of Alzheimer's disease (AD) and that estrogen replacement therapy may be protective. One of the major pathological features in the human AD brain is the senile plaque, a proteinaceous structure composed mainly of heterogeneous peptides collectively known as A-beta (Aβ). In vitro studies have linked estrogen with Aβ modulation, suggesting that one-way that estrogen depletion at menopause may exacerbate the features of AD is through Aβ accumulation. To test this, two studies were performed on transgenic models of amyloidosis. Firstly, transgenic mice without detectable amyloid aggregates were subjected to ovariectomy and estradiol supplementation, and Aβ levels were assessed. Secondly, the effects of estrogen modulation were assessed in mice at an age when plaques would be forming initially. Overall, Aβ levels were higher in estrogen-deprived mice than intact mice, and this effect could be reversed through the administration of estradiol. These data suggest that, in vivo, estrogen depletion leads to the accumulation of Aβ in the CNS, which can be reversed through replacement of estradiol. These results provide evidence that post-menopausal estrogen depletion may be linked to an increased risk of AD through Aβ modulation.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 58 (2001), S. 0 
    ISSN: 1095-8649
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Analysis of mitochondrial (ND-1/3/4 genes) and nuclear (GH-1 gene, four microsatellite loci) DNA markers of European grayling Thymallus thymallus populations identified strong genetic differentiation between the Rhine/Main, Elbe and Danube drainages in Bavaria, as a result of both present processes and past history. The Danube and the Main-Elbe group diverged about five times earlier than the populations of Main and Elbe. These data suggest that exchange and transfer of grayling stocking material between these drainages should be avoided, to maintain the genetic diversity and integrity of populations.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    s.l. : American Chemical Society
    Journal of the American Chemical Society 92 (1970), S. 2179-2180 
    ISSN: 1520-5126
    Quelle: ACS Legacy Archives
    Thema: Chemie und Pharmazie
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Journal of geodesy 73 (2000), S. 627-637 
    ISSN: 1432-1394
    Schlagwort(e): Key words: Earth rotation – Combination – Kalman filter
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung
    Notizen: Abstract. Independent Earth-orientation measurements taken by the space-geodetic techniques of lunar and satellite laser ranging, very-long-baseline interferometry, and the global positioning system have been combined using a Kalman filter. The resulting combined Earth-orientation series, SPACE97, consists of values and uncertainties for universal time, polar motion, and their rates spanning the period 28 September 1976 to 3 January 1998 at daily intervals. The space-geodetic measurements used to generate SPACE97 have then been combined with optical astrometric measurements to form two additional combined Earth-orientation series: (1) COMB97, consisting of values and uncertainties for universal time, polar motion, and their rates spanning the period 20 January 1962 to 1 January 1998 at 5-day intervals, and (2) POLE97, consisting of values and uncertainties for polar motion and its rate spanning the period 20 January 1900 to 21 December 1997 at monthly intervals.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular medicine 49 (1971), S. 1301-1304 
    ISSN: 1432-1440
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular medicine 50 (1972), S. 985-985 
    ISSN: 1432-1440
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Methionin-Synthetase ist ein Schlüsselenzym in der Synthese von Nucleoproteiden. Ein einfaches Verfahren für die routinemäßige Bestimmung wurde in unseren Arbeitskreisen entwickelt. Die Kontrolle dieses Enzyms läßt wichtige Ergebnisse, besonders für die Diagnose und Therapie bösartiger Erkrankungen, erwarten.
    Notizen: Summary Methionin synthetase is a key enzyme in nucleoprotein synthesis. A simple method for its routine estimation was developed. Sequential determinations may become an important parameter in cell metabolism, especially in relation to diagnostics and therapy of neoplastic diseases.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Journal of molecular medicine 51 (1973), S. 471-473 
    ISSN: 1432-1440
    Schlagwort(e): de novo synthesis nucleic acids ; orotic acid ; glycine ; l-asparaginase ; methotrexate ; lymphocyte cytoaggressiveness or cytotoxicity ; lymphocyte blastogenesis ; Nucleinsäuren von Lymphocyten ; l-Asparaginase ; lymphocytäre Cytoagressivität
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Menschliche Lymphocyten entwickeln bei einer Stimulierung mit PHA eine de novo-Synthese von Nucleinsäuren, was sich, von der 20. Std von Versuchsbeginn an, in einem zunehmenden Einbau markierter Vorstufen von Purinen und Pyrimidinen in die Nucleinsäuren der Lymphocyten äußert. Immunosuppressiv wirkende Substanzen wie l-Asparaginase, Prednisolon und Azathioprin verhindern diese de novo-Synthesen und gleicherweise die Blastogenese der stimulierten Lymphocyten wie auch ihren cytoaggressiven Effekt. Demgegenüber verhindert Methotrexat diese Reaktionen nicht, obwohl die bekannte Wirkung von Methotrexat auf den Zellstoffwechsel auch bei stimulierten Lymphocyten beobachtet werden kann. Der Mechanismus der immunosuppressiven Wirkung von Methotrexat in vivo wird durch diese Befunde eher unklar.
    Notizen: Summary Human lymphocytes develop a de novo synthesis of nucleic acids after stimulation with phytohaemagglutinin (PHA) which is shown by an increasing incorporation of labelled precursors of purines and pyrimidines into the nucleic acids of the lymphocytes beginning at the 20th hour of the experiment. Immunosuppressive substances as l-asparaginase, prednisolone and azathioprine inhibit these de novo syntheses and, likewise, the blastogenesis of the stimulated lymphocytes and their cytoaggressive effect. Methotrexate, however, does not inhibit these reactions, although its well known effect upon the cell metabolism may also be observed with stimulated human lymphocytes. The mechanism of the immunosuppressive effect of methotrexate in vivo is yet rendered less clear by these results.
    Materialart: Digitale Medien
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