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  • 1995-1999  (9)
  • 1915-1919
  • 1910-1914
  • 1998  (9)
  • 1
    Electronic Resource
    Electronic Resource
    Modification of InAs quantum dot structure by the growth of the capping layer (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 49-51 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: InAs quantum dots inserted at the middle of a GaAs quantum well structure have been investigated by transmission electron microscopy and scanning transmission electron microscopy. We find that the growth condition of the overlayer on the InAs dots can lead to drastic changes in the structure of the dots. We attribute the changes to a combination of factors such as preferential growth of the overlayer above the wetting layers because of the strained surfaces and to the thermal instability of the InAs dots at elevated temperature. The result suggests that controlled sublimation, through suitable manipulation of the overlayer growth conditions, can be an effective tool to improve the structure of the self-organized quantum dots and can help tailor their physical properties to any specific requirements of the device applications. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121719
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  • 2
    Electronic Resource
    Electronic Resource
    Transport properties of two-dimensional electron gases containing InAs self-assembled dots (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 73 (1998), S. 2468-2470 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a study of the transport properties of two-dimensional electron gases formed in GaAs/AlGaAs heterostructures in which InAs self-assembled quantum dots have been inserted in the center of a GaAs quantum well. We observed that, while maintaining a constant carrier density, the mobility increased as the InAs dot density was reduced. The ratio of the transport to the quantum lifetime was measured to be approximately five with the dominant scattering mechanism attributed to short-range scattering from the inserted InAs dots. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.122484
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gingival inflammation and subgingival calculus as determinants of disease progression in early-onset periodontitis (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of clinical periodontology 25 (1998), S. 0 
    Details
    ISSN: 1600-051X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract. This study was undertaken to test the hypothesis that gingival inflammation and dental calculus are important determinants of the development and progression of early-onset periodontitis. The study sample included 156 individuals who were 13–20 years old at baseline and who were examined 2× during 6 years to assess the attachment loss, gingival state and the presence of dental calculus. 33 (21%), 62 (40%), and 61 (39%) individuals were classified as having localized, generalized, or incidental EOP, respectively. The results showed an increase in the % of teeth with overt gingivitis and subgingival calculus, and also an increase in the % of teeth showing attachment loss during the 6-year period in ail classification groups. Of teeth with 0–2 mm attachment loss at the beginning of the study and which developed ≥3 mm attachment loss during the following 6 years, there were 2× as many teeth with overt gingival inflammation, and 4× more teeth with subgingival calculus at baseline than teeth without. Gingivitis and subgingival calculus when present at both examinations resulted in a stronger association with the development of new lesions than presence of these variables at baseline. Teeth with gingivitis at baseline had a significantly higher mean attachment loss during 6 years than teeth without gingivitis (p〈0.0001), and teeth with subgingival calculus at baseline had a significantly higher mean attachment loss than teeth without subgingival calculus (p〈0.0001), The presence of gingivitis and subgingival calculus at baseline and 6 years later was associated with the occurrence of even higher disease progression during this period. The association between gingival inflammation and subgingival calculus and the development and progression of attachment loss during the study period in the generalized and the localized EOP groups was significantly higher than the association in the incidental EOP group. In an appreciable % of the sites in all 3 groups, however, the presence of the 2 factors was not associated with attachment loss during 6 years. The results suggest a significant association between gingival inflammation and subgingival calculus and the development and progression of early-onset periodontitis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-051X.1998.tb02433.x
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  • 4
    Electronic Resource
    Electronic Resource
    Substrate mediated photochemistry on a molecular surface: OCS on Ag clusters (1998)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 2474-2479 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photochemistry of carbonyl sulfide (OCS) adsorbed to small silver clusters is shown to exhibit a striking odd–even dependence on the number of Ag atoms in the cluster. OCS is found to desorb nondissociatively from even numbered silver clusters. In contrast, on odd silver clusters, a new product channel corresponding to AgnS is observed. Parallels are found with the photochemistry of adsorbates on extended surfaces. Cross-section measurements for OCS desorption from Ag10 and wavelength-dependent measurements of OCS dissociation on Ag9 both indicate that electronic excitation of the cluster initiates chemistry, analogous to substrate mediated surface photochemistry. The size dependence is reasonably explained in terms of a charge-transfer mechanism involving an ion-pair state of the AgnOCS complex. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.476818
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  • 5
    Electronic Resource
    Electronic Resource
    A site for sore eyes (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 395 (1998), S. 134-135 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] ... Microscopes are to modern science what telescopes are to astronomy: a great enabling technology, which has brought about a considerable part of what is now undergraduate physics. Yet microscopy remains a discipline for professionals, and stands quite aloof from mainstream academic science, ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/25916
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  • 6
    Electronic Resource
    Electronic Resource
    Nanofabrication of solid- state Fresnel lenses for electron optics (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 394 (1998), S. 49-52 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Lenses for precision electron optics are mainly magnetic, requiring large cylinders of soft iron to focus an electron beam. Such lenses can only be convergent, and so suffer from spherical aberration. Electrostatic lenses are sometimes used, but tend to be even more cumbersome. The advent of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/27863
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  • 7
    Electronic Resource
    Electronic Resource
    Multiple field and glasshouse assessments increase the reliability of linkage mapping of the Vf source of scab resistance in apple (1998)
    Springer
    Theoretical and applied genetics 96 (1998), S. 699-708 
    Details
    ISSN: 1432-2242
    Keywords: Key words Malus ; Apple ; Venturia ; Scab resistance ; Linkage mapping ; Cluster analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Apple scab, caused by the fungus Venturia inaequalis (Cke.) Wint., is an important disease in commercial apple production. A mapping population of 155 individuals, derived from a cross between the apple varieties ‘Prima’ (resistant)בFiesta’ (susceptible), was scored for response to the disease in replicated field and glasshouse trials throughout Europe. Twenty data sets were selected and cluster analysis was used to form a consensus score for the population fitting a 1 : 1 segregation ratio of resistance:susceptibility. The progeny were scored with molecular markers. A detailed map covering 54 cM of the ‘Prima’ linkage group containing the Vf gene for scab resistance was constructed using 24 molecular markers linked to the resistance gene. One isoenzyme marker (Pgm-1), six RFLP markers and 17 RAPD markers formed a linkage group with the consensus measure of resistance to scab. Four marker bridges were established with the corresponding ‘Fiesta’ linkage group with additional markers (one isozyme, one RFLP, three RAPD and one AFLP). A low chi-square value indicated a good fit of the marker ordering, which was in close agreement with previously reported linkage positions for some of the markers and Vf. Differences were observed in the ability of different scoring methods to resolve susceptible and resistant classes. The results obtained for the consensus classification of resistance to scab for the population may suggest the presence of virulent inocula at some sites, which could overcome the Vf gene for resistance. The consequences of relying on individual scoring occasions for studying Vf scab resistance are discussed in the context of linkage analysis, conventional breeding selection, and marker-assisted selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050791
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  • 8
    Electronic Resource
    Electronic Resource
    Aligning male and female linkage maps of apple (Malus pumila Mill.) using multi-allelic markers (1998)
    Springer
    Theoretical and applied genetics 97 (1998), S. 60-73 
    Details
    ISSN: 1432-2242
    Keywords: Key wordsMalus pumila Mill ; Molecular linkagemap ; Marker-assisted selection ; Fruit tree breeding ; Outbred progeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Linkage maps for the apple cultivars ‘Prima’ and ‘Fiesta’ were constructed using RFLP, RAPD, isozyme, AFLP, SCAR and microsatellite markers in a ‘Prima’בFiesta’ progeny of 152 individuals. Seventeen linkage groups, putatively corresponding to the seventeen haploid apple chromosomes, were obtained for each parent. These maps were aligned using 67 multi-allelic markers that were heterozygous in both parents. A large number of duplicate RFLP loci was observed and, in several instances, linked RFLP markers in one linkage group showed corresponding linkage in another linkage group. Distorted segregation was observed mainly in two regions of the genome, especially in the male parent alleles. Map positions were provided for resistance genes to scab and rosy leaf curling aphid (Vf and Sd 1, respectively) for the fruit acidity gene Ma and for the self-incompatibility locus S. The high marker density and large number of mapped codominant RFLPs and some microsatellite markers make this map an ideal reference map for use in other progenies also and a valuable tool for the mapping of quantitative trait loci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220050867
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  • 9
    Electronic Resource
    Electronic Resource
    Magnetic Characteristics of Ball-Milled Nd2Fe14B - Gd (1998)
    Springer
    Hyperfine interactions 112 (1998), S. 85-88 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Mössbauer measurements using 57Fe and 155Gd have been made on samples of ball-milled Nd2Fe14B in a gadolinium matrix in order to determine the magnetisation of each phase separately. Although magnetometer measurements did not show any coercivity, both measurements showed the phases were in intimate magnetic contact. The spectra of each phase differed considerably from those of the respective original materials and provide information on the conduction electron polarisation through the transferred hyperfine fields.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011036627157
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