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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Integral equations and operator theory 13 (1990), S. 553-575 
    ISSN: 1420-8989
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Generalizing the Cowen-Douglas-Theory to certain tuples of unbounded symmetric operators we obtain canonical models for such tuples, which are realized in holomorphic functional Hilbert spaces. The results are applied to multidimensional moment problems.
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  • 2
    ISSN: 1434-601X
    Keywords: 25.30.Fj ; 21.10.Pc ; 02.60.Ed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A method for the separation of structure functions in (e, e′ p) experiments is proposed, which is an extension of the traditional Rosenbluth-type techniques of [1,2]. In our approach, we use a very flexible Ansatz to describe the structure functions within an extended kinematical regionG and determine its free parameters with a x2 minimization. The procedure is tested by pseudo data (12C(e, e′p)11Bg.s.) in the quasi-free region.
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  • 3
    ISSN: 1434-6036
    Keywords: 61.50.−f ; 35.20.Jv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We exploited the slow relaxation of methyl group rotational tunneling states to perform optical hole burning inn-alkane crystals. The dye probe used was dimethyl-s-tetrazine and its perdeuterated derivative. We investigatedn-octane, perdeuteratedn-octane andn-hexane as host crystals. By comparing the experimentally observed hole-antihole splitting of the protonated and perdeuterated dye probe, all parameters, i.e. the tunneling splitting in the ground-and in the electronically excited state as well as the respective heights of the potential can be determined, assuming a threefold rotational symmetry axis. We found that matrix deuteration has a severe influence on the potential heights, which increase by a factor of two. With these parameters determined, many features of the complex relaxation behavior of the tunneling states can be qualitatively understood: We found Raman-type conversion processes inn-octane-h 18, Orbach-type processes inn-octane-d 18 and inn-hexane we found, in addition, a relaxation regime governed by a Direct process. The experimental activation energies as well as the cross-over temperatures are in satisfying agreement with current theories.
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  • 4
    ISSN: 1573-5109
    Keywords: Triticum aestivum ; Aegilops tauschii (syn. Ae. squarrosa) ; Erysiphe graminis f. sp. tritici resistance genes ; gene expression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A collection of 400 Ae. tauschii (syn. Ae. squarrosa) Coss. accessions were screened for powdery mildew resistance based on the response patterns of 13 wheat cultivars/lines possessing major resistance genes to nine differential mildew isolates. 106 accessions showed complete resistance to all isolates, and 174 accessions revealed isolate-specific resistance, among which were 40 accessions exhibiting an identical response pattern as wheat cultivar ‘Ulka/*8Cc’ which is known to possess resistance gene Pm2. Expression of both complete and isolate-specific resistance from Ae. tauschii was observed in some synthetic hexaploid wheats derived from four mildew susceptible T. durum Desf. parents, each crossed with five to 38 resistant diploid Ae. tauschii accessions. Synthetic amphiploids involving different combinations of T. durum and Ae. tauschii generally showed a decrease in resistance compared with that expressed by the Ae. tauschii parental lines.
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  • 5
    ISSN: 1573-5060
    Keywords: common wheat ; Triticum aestivum ; resistance genes ; Erysiphe graminis tritici ; powdery mildew ; monosomic analysis ; allelism tests
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Several wheat cultivars/lines were inoculated with isolates of Erysiphe graminis tritici to identify new genes/alleles for resistance. The wheats were tested with 13 isolates that had been characterized from responses on differential lines with known resistance genes. Gene Mlk which occurs in cultivars ‘Kolibri’, ‘Syros’, ‘Ralle’ and several other European common wheats was found to be an allele at the Pm3 locus and is now designated Pm3d. The mildew resistance in an old Australian wheat, ‘W150’, is conferred by a single gene also allelic to Pm3 and now designated Pm3e. The near-isogenic line ‘Michigan Amber/8*Cc’ possesses another allele now designated Pm3f. A Syrian land variety of common wheat shows mildew resistance that is conditioned by the combination of genes Pm1 and Pm3a. Finally, two accessions of Triticum aestivum ssp. sphaerococcum appeared to possess the Pm3c allele.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 4371-4374 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Implantation of hydrogen at 600 °C into GaAs at 8 keV and at high doses resulted in the formation of a two-layer structure. The topmost layer roughly extended in depth to the range of the protons and exhibited a high concentration of loops, hydrogen bubbles, decorated dislocations, and faults. Occasional microsplits on {110} were observed. The deeper layer contained pressurized hydrogen platelets on {111}. These results are critically compared with previous results obtained with cold implanted and subsequently annealed GaAs. The present observations are also discussed in relation to the theoretical treatment by d'Olieslaeger [J. Mater. Sci. 23, 2697 (1988)]. Estimates of the importance of arsine production are also presented.
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  • 7
    ISSN: 1617-4623
    Keywords: Aflatoxin B1 ; Cytochrome P450 ; Rat hepatoma cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We present a strategy to elucidate the rate-limiting steps in activation of carcinogenic compounds by cytochromes P450. The principle was to select Reuber rat hepatoma cells for resistance to a procarcinogen. The hypothesis was that resistant cells should be systematically deficient in the P450 enzyme(s) involved in the activation process. Here we present an example of the use of this approach using aflatoxin B1 (AFB1), a potent hepatocarcinogen, as the selective agent. Parental cells as well as individual and pooled colonies selected for AFB1 resistance from three independent rat hepatoma lines were characterized for their content of 1) mRNA hybridizing to cDNA and/or oligonucleotide probes for cytochromes P450IIB1, P450IIB2 and albumin; and 2) aldrin epoxidase activity. Parental aflatoxin B1-sensitive cells were shown to express P450IIB1 but not P450IIB2. The majority of the aflatoxin B1-resistant clones failed to accumulate cytochrome P450IIB1 mRNA and expressed no or only very low aldrin epoxidase activity. Albumin mRNA levels remained unchanged, demonstrating that loss of expression of cytochrome P450IIB1 was not a consequence of a general dedifferentiation event. A revertant population showing restoration of both cytochrome P450IIB1 mRNA accumulation and aldrin epoxidase activity was fully sensitive to aflatoxin B1. The correlation between expression of cytochrome P450IIB1 and sensitivity to aflatoxin B1 in both parental cells and revertants strongly suggests that cytochrome P450IIB1 is a major contributor to the activation of aflatoxin B1 in rat hepatoma cells. The kind of strategy described here could be applied to other compounds that become cytotoxic for hepatoma cells following activation by cytochromes P450.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Biologie in unserer Zeit 21 (1991), S. 248-254 
    ISSN: 0045-205X
    Keywords: Life and Medical Sciences
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Seitdem der abendländische Mensch erkannt hatte, daß sich Getreidekörner, besonders die des Weizens, zur Mehl- und Brotherstellung eignen, ist er auf Gedeih und Verderb mit dieser Pflanzenart verbunden. Ohne den Einfluß des Menschen wären die Kulturformen von Weizen, Reis, Gerste, Hafer und Mais nicht denkbar. War er es doch, der entscheidend dazu beigetragen hat, daß sich im Laufe von Jahrtausenden unsere wichtigsten Getreidearten von ehemals spindelbrüchigen Gräsern, deren Samen nach der Reife auf den Boden fielen, Schrittweise zu zähspindeligen, nichtährenbrüchigen Hochleistungs-Nutzpflanzen umwandelten.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 41 (1990), S. 553-554 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
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  • 10
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Two different hypotheses of the phenomenological process of etching of polymer films in a non isothermal oxygen plasma of a high frequency discharge are discussed: the successive etching on the surface and the formation of an etch-resistant surface layer with a shifting of the degradation processes in polymer bulk. This second model proposed by Valiev requires a complicated system of diffusion processes of plasma species and degradation products. Our findings are in contrast to those of Valiev, but it seems that the plasma modified surface layer plays a dominant role within the ablation process.
    Notes: Zwei unterschiedliche Vorstellungen zum Ablauf des Abtrags von Polymerschichten in einem nichtisothermen Sauerstoffplasma einer elektrischen Hochfrequenzentladung werden diskutiert: der successive Abbau an der Oberfläche und die plasmaphysikalische Verfestigung der Polymeroberfläche bei gleichzeitiger Verlagerung des Abbaus in des Polymervolumen. Das letztgenannte Modell von Valiev verlangt komplizierte Diffusionsprozesse von abbaufähigen Plasmaspezies und entsprechenden Abbauprodukten. Die hier durchgeführten Modellversuche sprechen in ihren Ergebnissen gegen das Modell von Valiey, wobei jedoch die plasmamodifizierte Polymeroberflächenschicht tatsächlich eine besondere Rolle beim Abbau der gesamten Polymerschicht spielt.
    Additional Material: 3 Ill.
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