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  • 1995-1999  (23)
  • 1990-1994
  • 1999  (23)
  • 1
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 2845-2847 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A nanoscale electron tube with a field-emission cathode and a control gate (nanotriode) has been fabricated and characterized. Electrons are field emitted from metal nanopillars with radii of about 1 nm into a vacuum nanochamber, collected at the anode, and controlled by a gate electrode. The nanochamber is sealed by an integrated anode and has vertical and horizontal dimensions of 100 nm. The turn-on voltage is less than 10 V and is independent of ambient temperature. Currents of 10 nA and transconductances of up to 6 nS per device have been observed; this would yield a transconductance of 60 S cm−2 at the maximum packing density of 1010 nanotriodes cm−2 for these devices. The emission stability is better than 3% at room temperature and improves to 0.1% at 20 K. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 22 (1999), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Transgenic potatoes expressing reduced levels of granule-bound starch synthase I (GBSSI) have been used to investigate whether the synthesis of amylose occurs at the surface of the starch granule or within the matrix formed by the synthesis and organization of amylopectin. Amylose in these potatoes is wholly or largely confined to a central region of the granule. Consequently this core region stains blue with iodine whereas the peripheral zone stains red. By making extensive measurements of the relative sizes of the granules and their blue-staining cores in tubers over a range of stages of development, we have established that the blue core increases in size as the granule grows. The extent of the increase in size of the blue core is greater in potatoes with higher levels of GBSSI. These data show that amylose synthesis occurs within the matrix of the granule, and are consistent with the idea that the space available in the matrix may be an important determinant of the amylose content of storage starches.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Journal of advanced nursing 30 (1999), S. 0 
    ISSN: 1365-2648
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Perceived family dynamics of persons with chronic pain This qualitative study was conducted to gain an understanding of the experiences of persons with chronic pain and their relationships with family members and the family as a whole. The framework of systemic organization was used to define the areas of investigation guiding the formulation of broad questions relative to family functioning. Thirty persons with chronic pain (age 31–82 years, 73% women, 83% married, 83% European-American, 17% African-American) participated in the study. A semi-structured interview was conducted to elicit narrative descriptions of the participants’ perspective of the pain experience and family functioning. The data were analysed using a constant comparison method of analysis described by Strauss. The dominant themes that emerged included: (i) emotional distress, (ii) distancing from family members, (iii) inability to share difficult feelings, (iv) intense mutual involvement with family members and identification with others’ problems, (v) family isolation from community, and (vi) attempt at healing. A mid-range theory developed out of the data and explicated with the framework of systemic organization, was one of balancing and counterbalancing connectedness (spirituality) with personal autonomy or separateness (control) in order to find congruence for the family and individuals within. The pain sometimes acted as a mechanism regulating the distance and closeness among family members. Based on this information, nurses can facilitate better understanding among family members, encourage autonomy, assist individuals to express feelings and needs more directly, and facilitate members to respond to each other.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 22 (1999), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Maize plants were grown at 14, 18 and 20 °C until the fourth leaf had emerged. Leaves from plants grown at 14 and 18 °C had less chlorophyll than those grown at 20 °C. Maximal extractable ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity was decreased at 14 °C compared with 20 °C, but the activation state was highest at 14 °C. Growth at 14 °C increased the abundance (but not the number) of Rubisco breakdown products. Phosphoenolpyruvate carboxylase (PEPC) activity was decreased at 14 °C compared with 20 °C but no chilling-dependent effects on the abundance of the PEPC protein were observed. Maximal extractable NADP-malate dehydrogenase activity increased at 14 °C compared with 20 °C whereas the glutathione pool was similar in leaves from plants grown at both temperatures. Foliar ascorbate and hydrogen peroxide were increased at 14 °C compared with 20 °C. The foliar hydrogen peroxide content was independent of irradiance at both growth temperatures. Plants grown at 14 °C had decreased rates of CO2 fixation together with decreased quantum efficiencies of photosystem (PS) II in the light, although there was no photo-inhibition. Growth at 14 °C decreased the abundance of the D1 protein of PSII and the PSI psaB gene product but the psaA gene product was largely unaffected by growth at low temperatures. The relationships between the photosystems and the co-ordinate regulation of electron transport and CO2 assimilation were maintained in plants grown at 14 °C.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of periodontal research 34 (1999), S. 0 
    ISSN: 1600-0765
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-2048
    Keywords: Key words:Arabidopsis (GTP binding) ; Cytokinin ; Ethylene ; Protein Phosphorylation ; GTP-binding proteins (small)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Binding of [α-32P]guanosine 5′-triphosphate ([α-32P]GTP) has been demonstrated in a Triton X-100-solubilised membrane fraction from leaves of Arabidopsis thaliana (L.) Heynh. Binding was stimulated by 1 h pre-treatment of leaves with ethylene and this effect was antagonised by the inclusion of N6-benzyladenine in the medium used for homogenisation. The ethylene-insensitive mutants eti5 and etr showed contrasting responses. In eti5 the constitutive level of GTP binding was higher than in the wild type whereas in etr the level was much lower. Neither ethylene nor cytokinin affected GTP binding in the mutants. The GTP-binding activity was localised in two bands at 22 and 25 kDa, both of which were immunoprecipitated by anti-pan-Ras antibodies, indicating that the activity is due to small GTP-binding proteins. In a similar membrane fraction, ethylene was shown to increase protein phosphorylation and benzyladenine antagonised this effect. In eti5 the constitutive level of protein phosphorylation was higher than in the wild type, but benzyladenine increased activity substantially while ethylene was without effect. In etr, protein phosphorylation was lower than in the wild type, ethylene was without effect, but cytokinin increased activity. A protein of Mr 17 kDa was detected on gels using antibodies to nucleoside diphosphate kinase. Phosphorylation of this protein was upregulated by ethylene but nucleoside diphosphate kinase activity was unaffected. The results are compared with the effect of the two hormones on the senescence of detached leaves and discussed in relation to pathways proposed for ethylene signal transduction.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1920
    Keywords: Key words Brain ischaemia ; Brain ; infarct ; Magnetic resonance imaging ; Magnetic resonance angiography ; Pulse sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the hyperacute phase of stroke, occluded vessels can be seen as high signal on fast-FLAIR images or as absence of flow-related enhancement in maximum-intensity projection (MIP) MR angiography (MRA). To compare these techniques, we examined 53 patients within 6 h of a stroke, using a standardised MRI protocol including fast-FLAIR and 3D time-of-flight TOF MR to detect vessel occlusion or reduced flow corresponding to the suspected ischaemic territory. Brain infarcts were confirmed on MRI after 1–5 days in 41 cases (77 %). The overall accuracy of 3D-TOF MRA was 68 % and sensitivity, specificity, positive and negative predictive values were 67 %, 71 %, 87 %, and 43 % respectively. Values for the fast-FLAIR sequence were: 65 %, 85 %, 93 % and 44 %, with an overall accuracy of 70 %. The fast-FLAIR sequence was thus able to show occluded vessels or reduced flow with about the same accuracy as 3D-TOF MRA and enabled better prediction of the ischaemic area.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 133-142 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Green's-function techniques are used to obtain a real-space series solution for the elastic reflection high-energy electron diffraction (RHEED) from a crystalline surface. A renormalized perturbation expansion due to potential self-scattering is developed for the local real-space Green's function. With the Pt (111) surface as an example, numerical results are obtained for reflection coefficients and intensities. In particular, calculations are performed to obtain the local density of states at and near the surface region. Total density-of-states calculations are also performed. These provide a basis for a discussion of the form of resonant electronic Green's functions that can be used to describe the surface resonance phenomenon within RHEED.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [s.l.] : Macmillan Magazines Ltd.
    Nature 400 (1999), S. 126-126 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In his classic studies on honeybee navigation, von Frisch had to rely on qualitative visual observations of the bees' flight paths, but nevertheless reached the surprising conclusion that bees seem to anticipate lateral wind drift and compensate by flying in shallow curves on the upwind side of ...
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chester : International Union of Crystallography (IUCr)
    Journal of synchrotron radiation 6 (1999), S. 201-203 
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
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