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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 3860-3864 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The conditions for the preparation of nominally undoped semi-insulating (SI) InP wafers by annealing under controlled phosphorus pressure are described. It is demonstrated by the results of electrical profile measurements (differential Hall effect) and by photoluminescence that diffusion effects in a thin peripheral layer (≈20 μm) can be correlated to a phosphorus in- and indium out-diffusion. But diffusion of these species is correlated to a donor behavior and relatively slow. It can, therefore, not be used to explain the SI bulk property which seems not to depend on the phosphorus overpressure during annealing.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 2849-2851 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electron effective masses for Al0.15Ga0.35In0.5P and Ga0.5In0.5P have been investigated using conventional and optically detected cyclotron resonance. For AlGaInP (partly ordered) it is determined to be m*=(0.14±0.01) m0. For disordered GaInP the mass is found to be m*=(0.092±0.003) m0 and for ordered material (band gap reduction ∼50 meV) m*=(0.088±0.003) m0. The experimentally deduced values are compared with those obtained from five-band k⋅p calculation.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Pediatric allergy and immunology 2 (1991), S. 0 
    ISSN: 1399-3038
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: In 70 children with defined chronic chest disease, immunoglobulins, IgG subclass levels and antibody concentrations specific for Haemophilus influenzae b (Hib), and pneumococcal antigen, were related to disease severity. Bronchological examinations revealed 30 children with chronic bronchitis, 21 with bronchial deformations and 19 with bronchiectasis. Of the 70 children 12 (17.1%) showed an underlying immunodeficiency. The commonest finding was an IgG subclass deficiency, 7 were IgG2 and 1 IgG3 deficient, followed by IgA deficiency in 3 patients. All patients had normal IgG and IgM levels except one who had immunodeficiency with elevated IgM. Pneumococcal antibody levels were found to increase between patient groups in the order healthy children 〈 chronic bronchitis 〈 bronchiectasis 〈 bronchial deformations (p 〈 0.01), but this was not the case for Hib antibodies. We found no selective deficiency of pneumococcal and Hib antibodies in our patients. Pathogens were detected in bronchial cultures from 10% of patients with chronic bronchitis, 33% of those with bronchial deformations and in 63% with bronchiectasis. This increase (p 〈 0.01) reflects a more severe inflammation of the respiratory tract in such patients. However, immunodeficiencies were equally distributed between patient groups. We conclude that only a subgroup of children with chronic chest disease have an underlying immunodefiency, but most patients (83%) do synthesize normal or even high antibodies in the presence of a bacterial load.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1440
    Keywords: Coronary artery disease ; Hibernating myocardium ; PTCA ; Recanalization ; Regional wall motion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Percutaneous transluminal coronary angioplasty can be performed safely and effectively in patients with chronic total coronary occlusion. To investigate the effect on left ventricular function, global and regional left ventricular ejection fraction were analyzed by contrast angiography in 49 patients before and 10±6 weeks after successful recanalization. Coronary angiography at follow-up showed reocclusion in 12 patients (24%). In 37 patients with patent arteries global ejection fraction increased from 55.8±7.1% at baseline to 62.5 ± 11.3% at follow-up (P 〈 0.001), and regional wall motion assessed by the centerline method improved from −1.7 + 1.0 to – 0.6 ± 1.5 standard deviations/chord (P〈0.001). In contrast, in patients with reocclusion neither global ejection fraction nor regional wall motion were significantly different at follow-up compared with baseline. Changes in global or regional left ventricular function after coronary recanalization were unrelated to other parameters such as severity of angina, duration of occlusion, history of myocardial infarction, presence or absence of visible collaterals, or baseline left ventricular function. Thus in patients with primarily successful recanalization of chronically occluded coronary arteries persistent vessel patency is the major determinant of global and regional improvement of left ventricular function.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Pediatric radiology 21 (1991), S. 89-93 
    ISSN: 1432-1998
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Pediatric airway obstruction due to anomalies of the course of the innominate artery may produce respiratory distress. MR imaging of the trachea was performed after bronchoscopy on forty-one children with congenital tracheal stenosis. Bronchoscopy only allows the evaluation of the lumen of the trachea, and the degree and location of collapse, and it may be difficult to determine the etiology of the tracheal narrowing. In eighteen out of the forty-one patients MR imaging showed a compression of the trachea by the innominate artery. The MR imaging diagnoses were subsequently compared for accuracy with the diagnoses determined by direct surgical observations. MR imaging of the trachea, the surrounding tissue and vessels allows the evaluation of the cause of tracheal compression and the degree and location of collapse. For evaluation of the cause of airway obstruction, MRI is an ideal method depicting detailed anatomic structure without employing ionizing radiation or intravenous contrast medium.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] According to current theory of the tropospheric ozone budget, photochemical production and stratospheric flux are principal sources of ozone, which are balanced by photochemical destruc-tion and surface deposition2"5. The photochemical production of ozone is mainly limited by the availability of ...
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 349 (1991), S. 659-659 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] SIR-The background level of non-volcanic stratospheric sulphate aerosol may be increasing at a rate of about 5 per cent per year1. This increase is believed to be due to an increase in sulphuric acid in the stratosphere, possibly derived from sulphurous gases emitted naturally and ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 349 (1991), S. 300-305 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Measurements of the vertical ozone profile with balloon-borne sensors in the Arctic during January and February 1990 indicate repeated minima in the 22-km region. A general negative correlation of the 22-km ozone mixing ratio with time spent by the air parcel in regions cold enough for the ...
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 12 (1991), S. 391-400 
    ISSN: 1573-0662
    Keywords: PIXE ; preconcentration ; freeze-drying ; rainwater ; fogwater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract PIXE is a well established and valuable method for quantitative and qualitative aerosol elemental analysis. Using this method, we have developed a technique to simultaneously analyse the trace-element content in precipitation for elements with Z〉 12. Freeze-drying and leaching was used as a nonselective preconcentration technique. A special backing foil to take up the sample liquid to be dried was developed for these experiments. By careful adjustment of the experimental parameters, we reached a detection limit lower than 1 ppb for most detected elements. Thus, it will be possible to analyze precipitation at low concentrations of trace elements which are important for air chemistry and environmental studies.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Hydrobiologia 216-217 (1991), S. 53-59 
    ISSN: 1573-5117
    Keywords: Cnidaria ; Cassiopea ; reproduction ; budding ; cell recruitment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cassiopea andromeda scyphistomae reproduce asexually by forming spindle shaped buds which, after detachment, metamorphose into polyps. Parent polyps appear to contribute to the buds' ecto- and endodermal epithelial cells, septal muscle cells, nematocytes and some zooxanthellae. Herein we describe bud morphogenesis, define 5 bud stages, and investigate the recruitment of bud ectoderm. India ink vital marking experiments reveal permanent apicobasal displacement of ectoderm. Labelled polyp cells are displaced towards and incorporated into the emerging bud. Ectoderm is recruited from all angular positions and cells labelled at increasing distances from the bud center are traced at increasingly more proximal positions on the buds. Unlike in Hydra attenuata, the recruitment area appears to be asymmetric since the zone contributing ectoderm from below is smaller than the zones above and lateral to the buds.
    Type of Medium: Electronic Resource
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