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  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 1002-1004 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have spatially resolved the photoluminescence patterns emitted from a GaAs/Al0.3Ga0.7As quantum well after femtosecond laser excitation for different electric bias fields applied in the plane of the well. These patterns demonstrate substantially different electron–hole dynamics across the excitation laser spot. The density dependence of screening combines with the lateral variation of the carrier density to produce the observed effects. These results prove that the spatial variation of the carrier dynamics is to be taken into account for the optimization of photoconductive switches as ultrafast voltage pulse sources or THz emitters. © 2000 American Institute of Physics.
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Surface Science 196 (1988), S. 156-164 
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0039-6028
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0827
    Keywords: Key words: Rheumatoid arthritis — Osteopenia — Disease activity — Vitamin D metabolites.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. In several studies on patients with rheumatoid arthritis, an association of bone loss with a persistently high disease activity has been found. The aim of our study was to investigate the relation between disease activity and serum levels of vitamin D metabolites, parathyroid hormone (PTH), and parameters of bone turnover in patients with rheumatoid arthritis. A total of 96 patients (83 women and 13 men) were divided into three groups according to disease activity measured by serum levels of C-reactive protein (CRP). In the whole group, serum levels of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) (P 〈 0.001) and PTH (P 〈 0.05) were negatively correlated to disease activity. The urinary excretion of collagen crosslinks—pyridinoline (Pyd) (P 〈 0.001) and deoxypyridinoline (Dpd) (P 〈 0.05)—showed a positive correlation with disease activity. The inverse correlation between serum 1,25(OH)2D3 and disease activity was separately evident in patients with (P 〈 0.001) and without (P 〈 0.01) glucocorticoid treatment, in pre- (P 〈 0.01) and postmenopausal (P 〈 0.001) women, and in men (P 〈 0.01). 1,25(OH)2D3 and PTH serum levels were positively correlated to serum bone alkaline phosphatase (ALP) (P 〈 0.01). The results indicate that high disease activity in patients with rheumatoid arthritis is associated with an alteration in vitamin D metabolism and increased bone resorption. The decrease of 1,25(OH)2D3 levels in these patients may contribute to a negative calcium balance and inhibition of bone formation. Furthermore, low levels of 1,25(OH)2D3 as an endogenous immunomodulator suppressing activated T cells and the proliferation of cells may accelerate the arthritic process in rheumatoid arthritis.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 10 (1954), S. 23-24 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Bee dances indicating the position of feeding places situated at short distances from the hive show a great variability. They have only one element in common which seems suitable to this purpose: the “pull-dance” (Rucktanz), described by us earlier.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 71 (1998), S. 80-88 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. Here we prove the existence for a huge number of triples (d,g,n) of smooth complex projective curves $ X \subset {\bf P}^n $ with degree d, genus g and such that T P n |X is a stable vector bundle (approximatively, if g≤ (n + 2) d/n for n≥ 4 and g≤ (2/27)1/2 d 3/2 for n = 3).
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 6 (1950), S. 142-144 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In his work on the language of the honey-bees v.Frisch distinguishes two dances: a round-dance and a tail-wagging dance. The latter one occurs only when the feeding place is situated at a certain distance from the hive (at least 25 m). It indicates the direction of the feeding place.Baltzer andTschumi recently discovered yet another direction-indicating dance, called “sickle-dance” («Sicheltanz»). It occurred at distances of 3 to 17 m. Our Dutch bees showed this sickle-dance too. At the end of each sickle run the bee performs a short, characteristic “pull-dance”, directed in relation to the feeding place. Isolated pull-dances may be observed down to 2 m. Between 20 and 50 m, with growing distance of the feeding place, the sickle-dance gradually changes into a tail-wagging dance. There is some evidence that the indicated direction actually is chosen, even with very short distances of the feeding place.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Entomologia experimentalis et applicata 50 (1989), S. 61-67 
    ISSN: 1570-7458
    Keywords: Coleoptera ; Chrysomelidae ; northern corn rootworm ; western corn rootworm ; dispersal ; malaise trap ; habitat selection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les activités de vol de D. barberi (NCR) et D. virgifera virgifera (WCR) ont été contrôlées par l'utilisation de pièges ‘malais’ placés en lisière de deux petits champs de maïs. Les populations de ces coléoptères sont maximales quand le maïs fleurit, mais leurs captures sont restées faibles jusqu'à ce que les barbes du maïs aient été sèches. Les captures de NCR et, dans une plus faible mesure, celles de WCR ont alors augmenté et sont restées importantes pendant toute la saison. Les pièges ‘malais’ ont été conçus pour que les adultes pénétrant par les côtés opposés soient récoltés séparément. Les femelles de NCR capturées face au champ de maïs avaient tendance à contenir moins d'ovocytes mûrs que celles capturées du côté opposé. Ces observations appuient l'hypothèse que les femelles NCR émigrent des champs de maïs pour s'alimenter, quand les barbes et le pollen de maïs, aliments préférés, deviennent indisponibles, mais que les femelles NCR pleines d'ovocytes mûrs recherchent le maïs quand elles sont en quête de lieux de ponte.
    Notes: Abstract Flight activity of corn rootworm beetles, the northern (NCR), Diabrotica barberi (Coleoptera: Chrysomelidae), and western (WCR), D. virgifera virgifera, was monitored using malaise traps placed at the edges of two small cornfields. Populations of beetles in the fields peaked while corn was flowering, but capture in malaise traps remained low until silks had dried. Capture of NCR and (to a lesser extent) WCR then increased and remained high through the season. Malaise traps were constructed to permit separate collections of beetles that entered on each of two opposite sides. Female NCR that were captured in sides that faced toward corn tended to contain fewer mature eggs than those in sides facing away from corn. These findings support the hypothesis that female NCR emigrate from cornfields to feed when fresh silk and corn pollen (favored foods) become unavailable, but that egg-laden NCR actively seek corn when searching for oviposition sites.
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  • 9
    ISSN: 0009-286X
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Im folgenden werden Sicherheitseinrichtungen behandelt, die der Unter- und Überdrucksicherung chemischer Apparate dienen, insbesondere Tauchungen, Sicherheitsventile und Bruchsicherungen. Es wird auf ihre Konstruktion und Anwendung eingegangen und über Erfahrungen in chemischen Betrieben berichtet.
    Additional Material: 10 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 312 (1961), S. 110-120 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The photo reaction of excessive liquid trimethyl chlorosilane with chlorine was studied at various temperatures. ClSi(CH3)2CH2Cl, ClSi(CH3)2CHCl2, ClSi(CH3)2CCl3, ClSi(CH3)(CH2Cl)2, ClSi(CH3)(CH2Cl)(CHCl2), and ClSi(CH3)(CH2Cl)CCl3 have been isolated. RAMAN spectra of the liquid products were taken and assigned.The compounds containing chloro- and dichloro-methyl groups have been hydrolysed to the corresponding disiloxanes, whose raman and infrared spectra were also taken and assigned. Physical data of these substances are listed.
    Notes: Die Photochlorierungsreaktion des flüssigen Trimethylchlorsilans wurde bei verschiedenen Temperaturen mit einem Unterschuß an Chlor untersucht. Isoliert werden konnten ClSi(CH3)2CH2Cl, ClSi(CH3)2CHCl2, ClSi(CH3)2CCl3, ClSiCH3(CH2Cl)2, ClSi(CH3)(CH2Cl)CHCl2 und ClSi(CH3)(CH2Cl)CCl3. Von den flüssigen Produkten wurden die RAMAN-Spektren aufgenommen und eine Zuordnung zu den Grundschwingungen vorgenommen. Die Verbindungen mit CH2Cl- und CHCl2-Gruppen wurden durch Hydrolyse in die zugehörigen Disiloxane überführt, von denen gleichfalls RAMAN- und auch IR-Spektren aufgenommen und ausgedeutet wurden. Die üblichen physikalischen Daten der Substanzen werden mitgeteilt.
    Additional Material: 4 Tab.
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