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  • 1
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 3345-3346 
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: The Synchrotron Ultraviolet Radiation Facility (SURF II) at the National Institute of Standards and Technology, Gaithersburg, MD, USA, has served as a primary radiometric standard in the vacuum ultraviolet region since its conversion from a synchrotron to an electron storage ring in 1974. The magnet iron, however, dates back to an original betatron design of the late 1940s. The advent of both modern materials and methods of finite element analysis have made possible the design of magnets offering far greater dc performance than the existing SURF system. In this paper we discuss the general design and plans to convert SURF II to SURF III, which will offer reduced radiometric uncertainty, an increase in energy from 300 MeV to 385 MeV, a modernized control system, and two new beamlines, which are not presently possible. Anticipated new beamline activities include a substantial new effort devoted to radiometric improvements from IR to far UV and development of stations for microspectoscopy and electroreflectance. © 1996 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 70 (1997), S. 2750-2752 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Using an n-type (311)A GaAs substrate we have fabricated in situ back-gated GaAs/(Al,Ga)As hole gases with mobilities of μ=1.1×106 cm2 V−1 s−1 at 30 mK. We have investigated both experimentally and theoretically the scattering mechanisms that limit the mobility in both the [2¯33] and [011¯] directions. Using a combination of front and back gates to keep the carrier density constant, we can distinguish between scattering mechanisms which are primarily dependent on the carrier density and those that are sensitive to the shape of the hole wave function. This approach also eliminates complications arising from the variations of the Fermi surface anisotropy with carrier density. Our data confirms that anisotropic interface roughness scattering, arising from the nature of the (311)A GaAs surface, is the dominant scattering mechanism at carrier densities down to ps=5.0×1010 cm−2. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1365-3059
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The infection of tomato fruit by the postharvest pathogen Colletotrichum gloeosporioides did not proceed until the onset of ripening in response to ethylene. Compared with fruit from wild-type plants, infection progressed more slowly in transgenic fruit in which ethylene biosynthesis and ripening had been inhibited by an ACC oxidase (ACO) antisense transgene. In contrast, transgenic fruit deficient in polygalacturonase developed lesions at the same rate as the wild-type fruit. Ethylene biosynthesis increased rapidly in response to infection of ripe wild-type and ACO antisense fruit but was 25 times greater in the former. Fruit from the ripening mutant ripening inhibitor (rin), which are normally very resistant to infection, became infected quickly when incubated in the presence of ethylene, whereas fruit incubated in the absence of ethylene remained healthy. The ACO 1 mRNA accumulated to detectable levels within 24 h of inoculation of unripe wild-type fruit, prior to the development of visible symptoms, whereas there was no detectable expression in the inoculated ACO antisense fruit. ACO transcripts accumulated to maximum levels during the early stages of infection of ripe fruit, correlating with maximum ethylene biosynthesis. Northern analysis using gene-specific probes for each of the three ACO genes indicated that ACO 1 was the main gene expressed in response to infection and that there was no detectable expression of ACO 2 and 3.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 22 (1995), S. 0 
    ISSN: 1440-1681
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: 1. In attempting to consolidate the role of ventricular isomyosins in regulating the contractility of the myocardium, actomyosin ATPase and crossbridge kinetics were obtained at 24°C in chemically skinned isometrically contracting cardiac muscles containing V1 and V3 isomyosins.2. The ATPase activity was measured at various levels of Ca2+ activation by the enzymatic coupling of ATP hydrolysis with the conversion of NADH to NAD+. The crossbridge kinetics were inferred from small-amplitude perturbations of muscle length and muscle tension, and characterized by the frequency-domain parameter fmin.3. The ATPase rates of V1 and V3 muscles obtained at various levels of Ca2+ activation were plotted against the corresponding proportional tensions. The ATPase vs tension plots were linear with slopes of 4.92 nmol/min-1 per mm per mN and 1.98 nmol/min-1 per mm per mN, respectively for, V1 and V3 muscles. Individual calculations of ATPase-to-tension ratios (nmol/min-1 per mm per mN) gave corresponding averages of 4.98 ± 0.12 (s.e.m., n = 12) and 2.16 ± 0.12 (s.e.m., n = 10). The myosin isoform induced proportional change in tension cost was accompanied by a similar change in fmin (4.1 ± 0.1 Hz and 1.95 ± 0.03 Hz, means ± s.e.m., for V1 and V3 muscles, respectively).4. The observations and other published kinetic data are discussed in the context of models of crossbridge cycling. It is suggested that the tension economy of V3 muscle arises principally from an increase in the fraction of time, during the crossbridge cycle, when the crossbridge is exerting force.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1569-8041
    Schlagwort(e): anastrozole ; aromatase inhibitors ; breast cancer ; hormonal therapy ; letrozole ; review ; vorozole
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Three new aromatase inhibitors have recently completed phase III evaluation as treatment of metastatic breast cancer in post-menopausal women whose disease has progressed despite tamoxifen therapy: anastrozole (ARIMIDEX, Zeneca), letrozole (FEMARA, Novartis) and vorozole (RIVIZOR, Janssen). All belong to the third generation of non-steroidal aromatase inhibitors, and each is superior to previous generations in terms of potency and selectivity. The trials that have been performed compare each agent to megestrol acetate, and letrozole and vorozole to aminoglutethimide. Although the studies are not directly comparable due to differing study designs and patient populations, it has been demonstrated each of these drugs provides single agent, once-daily, oral palliation of hormone-responsive, post-menopausal metastatic breast cancer. Letrozole is clearly more effective than megestrol acetate, and anastrozole and vorozole are possibly so. All three are better tolerated than the progestin, particularly in terms of weight gain. Both letrozole and vorozole are significantly more effective, and better tolerated than aminoglutethimide. Overall, this most recent generation of aromatase inhibitors is a clear improvement on our current standard second-line therapies. In 1999, tamoxifen remains the first choice in the hormonal therapy of breast cancer. Following tamoxifen failure, the optimal second-line hormonal therapy remains undefined, but aminoglutethimide and megestrol acetate are no longer optimal therapy in this setting. The third-generation non-steroidal aromatase inhibitors must now be compared to each other, to the steroidal aromatase inhibitors, to the pure anti-oestrogens, and to tamoxifen.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 254 (1997), S. 297-303 
    ISSN: 1617-4623
    Schlagwort(e): Key words ACC oxidase  ;  Promoters  ;  Tomato  ;   Transposable elements
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  1-aminocyclopropane-1-carboxylate (ACC) oxidase, which catalyses the terminal step in ethylene biosynthesis, is encoded by a small multigene family in tomato that is differentially expressed in response to developmental and environmental cues. In this study we report the isolation and sequencing of approximately 2 kb of 5′-flanking sequence of three tomato ACC oxidase genes (LEACO1, LEACO2, LEACO3) and the occurrence of class I and class II mobile element-like insertions in promoter and intron regions of two of them. The LEACO1 upstream region contains a 420-bp direct repeat which is present in multiple copies in the tomato genome and is very similar to sequences in the promoters of the tomato E4 and 2A11 genes. The region covering the repeats resembles the remnant of a retrotransposon. Two copies of a small transposable element, belonging to the Stowaway inverted repeat element family, have been found in the 5′-flanking sequence and the third intron of LEACO3.
    Materialart: Digitale Medien
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  • 7
    ISSN: 1476-5535
    Schlagwort(e): Keywords: Alteromonas organophosphorus acid anhydrolase gene; X-Pro dipeptidase; sequencing and functional homology to prolidase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Organophosphorus acid anhydrolases (OPAA) catalyzing the hydrolysis of a variety of toxic organophosphorus cholinesterase inhibitors offer potential for decontamination of G-type nerve agents and pesticides. The gene (opa) encoding an OPAA was cloned from the chromosomal DNA of Alteromonas haloplanktis ATCC 23821. The nucleotide sequence of the 1.7-kb DNA fragment contained the opa gene (1.3 kb) and its flanking region. We report structural and functional similarity of OPAAs from A. haloplanktis and Alteromonas sp JD6.5 with the enzyme prolidase that hydrolyzes dipeptides with a prolyl residue in the carboxyl-terminal position. These results corroborate the earlier conclusion that the OPAA is a type of X-Pro dipeptidase, and that X-Pro could be the native substrate for such an enzyme in Alteromonas cells.
    Materialart: Digitale Medien
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