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  • 1
    Electronic Resource
    Electronic Resource
    Progressive multifocal leukoencephalopathy (PML) in AIDS and in the pre-AIDS era (1990)
    Springer
    Acta neuropathologica 80 (1990), S. 375-380 
    Details
    ISSN: 1432-0533
    Keywords: Progressive multifocal leucoencephalopathy (PML) ; AIDS ; Immunocytochemistry ; Nucleic acid hybridization ; Papova-virus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Twenty-five brains with definite, and three brains with possible, progressive multifocal leukoencephalopathy (PML), including six brains of AIDS patients, were studied with special regard to the detection of papovaviruses. Formalin-fixed serial paraffin sections were immunostained with monospecific anti-JC virus (JCV) and genus-specific anti-simian virus (SV) 40 antisera, and hybridized in situ with DNA probes for JCV and SV 40, respectively. Immunocytochemistry (ICC) and in situ hybridization (ISH) were similarly sensitive in detecting virus in classical PML lesions. In all but one definite PML cases at least one method detected virus (96%). Possible PML tissue was never labeled. Labeling patterns were generally similar in ICC and ISH: mainly oligodendroglia and, less frequently, astroglia harbored virus, whereas labeling of neurons and endothelia was absent. Bizarre giant astrocytes were occasionally labeled by ICC and ISH. Burnt-out lesions harbored JCV DNA but not virus antigens. SV 40 DNA was never detectable. PML morphology in AIDS cases did not usually differ from the disease process seen in the pre-AIDS era. However, two AIDS brains presented extremely extended and, in one case, unusually necrotizing PML damage; in the latter case, PML lesions contained large amounts not only of JCV, but also of human immunodeficiency virus (HIV) antigens. We conclude that ICC and ISH are methods of comparable sensitivity for detection of papovavirus in flourishing PML lesions. In burnt-out PML lesions only ISH may detect virus. The possibility of an exceptional non-JCV (e.g., SV 40) etiology of PML could be neither confirmed for disproved. In AIDS, massive coinfection by HIV of PML lesions may increase damage to tissue, resulting in unusually extended and necrotizing PML.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00307690
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  • 2
    Electronic Resource
    Electronic Resource
    Cytomegalovirus (CMV) disease of the brain in AIDS and connatal infection: a comparative study by histology, immunocytochemistry and in situ DNA hybridization (1989)
    Springer
    Acta neuropathologica 79 (1989), S. 286-293 
    Details
    ISSN: 1432-0533
    Keywords: Cytomegalovirus (CMV) ; Acquired immunodeficiency syndrome (AIDS) ; Encephalitis ; DNA hybridization ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Brain tissues from 45 patients with AIDS and two brains with connatal cytomegalic inclusion body disease were investigated for a cytomegalovirus (CMV) etiology of encephalitic lesions. Nineteen brains showed evidence of CMV infection by histology, immunocytochemistry (ICC) using two different antibodies (mono- and polyclonal), and in situ hybridization (ISH). Fourteen cases with typical cytomegalic cells in conventional histology [eight with focally necrotizing encephalitis/ventriculitis including the two connatal infections and six with nodular encephalitis (NE)] revealed CMV with any method. In 5 of 15 AIDS cases of NE without cytomegalic cells, CMV infection was established by ISH, whereas ICC remained negative in these cases. Typical lesions of human immunodeficiency virus (HIV)-induced multifocal giant cell encephalitis (HIV encephalitis) in 13 brains were never labeled for CMV. In necrotizing encephalitis/ventriculitis, cell types which labeled for CMV, with and without cytomegalic change, comprised neurons, astrocytes, oligodendrocytes, ependyma, choroid plexus, endothelia, and cells in periand endoneurium, and in leptomeninges. Both ISH and ICC were able to detect widespread non-cytomegalic CMV-infected cells in normal parenchyma, well beyound the necrotizing lesions, in two AIDS cases. Labeling patterns of nuclei versus cytoplasms varied between the three methods for CMV detection. We conclude that in CNS tissues with cytomegalic cells, ICC and ISH are of comparable sensitivity; however, a diagnosis of CMV disease is possible in such cases by conventional histology. For an in situ diagnosis of CMV infection in NE without cytomegalic cells in AIDS, ISH is the method of choice. A selective vulnerability to CMV infection of any specific cell type of the human CNS is absent. With our detection methods, typical lesions of HIV encephalitis do not show local co-infection by CMV.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00294663
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  • 3
    Electronic Resource
    Electronic Resource
    Atypical vertebral artery in a patient with an intra- and extraspinal cervical neurenteric cyst (1991)
    Springer
    Acta neurochirurgica 109 (1991), S. 150-153 
    Details
    ISSN: 0942-0940
    Keywords: Neurenteric cyst ; vertebral artery ; surgery ; cervical spine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 15 year old girl experienced Homer's syndrome on the right side, paraesthesia of the right arm and meningitis. CT and MRI showed a cystic lesion on the right side of the cervical spine at C3/C4 which descended with an extraspinal portion down to C6. Histology revealed a complex neurenteric cyst. The ipsilateral vertebral artery showed an atypical course. This abnormal artery besides a partial fusion of the vertebrae C2/C3/C4 suggest a complex malformation at the site of the cyst. Disturbed developmental relationships in this case indicate that pathological blood vessels may represent a risk factor in the surgical treatment of neurenteric cysts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01403012
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  • 4
    Electronic Resource
    Electronic Resource
    The Spatial Distribution of Defects and Its Dependence on Seed Polarity and Off-Orientation during Growth of 4H-SiC Single Crystals (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 527-529 (Oct. 2006), p. 9-14 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The defect distribution in 4H-SiC single crystals in dependence on the seed polarity andits off-orientation was investigated by KOH-etching, optical microscopy and X-ray topography.Micropipe density, stacking fault density and dislocation density were determined for 2” crystalsgrown in 〈000-1〉 direction 0 - 7° off towards 〈11-20〉 and for crystals up to 1” in diameter grownin 〈11-20〉 or a- and 〈1-100〉 or m-directions and using repeated a-face growth. For the growth inpolar directions the micropipe density and dislocation density decrease with increasing offorientationof the seed. A similar behavior was found for the stacking fault density and dislocationdensity in non-polar directions with off-orientation to c-direction. Nevertheless, while thedislocation density could be reduced up to three orders of magnitude for the growth along non-polardirections, the stacking fault density was continuously increasing. Additionally, the defectdistribution after repeated a-face growth will be discussed in terms of growth related and kineticmodels
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.527-529.9.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of Growth Parameters on the Residual Strain in 3C-SiC Epitaxial Layers on (001) Silicon (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 600-603 (Sept. 2008), p. 223-226 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: 3C-SiC epitaxial layers were grown on on-axis Si (001) substrates by low-pressure hot-wall chemical vapour deposition. Depending on the growth parameters, the residual strain in the 3C-SiC layer was seen to be tensile or compressive. In this work, the influence of parameters, such as growth temperature and C/Si ratio in the vapour phase, on residual strain and macroscopic layer bow is investigated. We found that the wafer bow changes from convex, at a deposition temperature of 1270° C, to concave at 1370° C. High resolution x-ray diffraction data indicate that the crystal-line perfection of the layers is lower for decreasing deposition temperature and increasing compres-sive strain. No remarkable influence of the C/Si ratio in the gaseous atmosphere on the FWHM of the rocking curve was observed
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/20/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.600-603.223.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Strong multi-electron excitations in the C 1s photoionization of CO and CO"2
    Amsterdam : Elsevier
    Chemical Physics Letters 199 (1992), S. 119-123 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(92)80057-I
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  • 7
    Electronic Resource
    Electronic Resource
    Angle-resolved photoelectron spectroscopy of the core levels of N2O (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 5299-5305 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured photoionization cross sections and photoelectron asymmetry parameters for each of the core levels of N2O. We have also carried out frozen- and relaxed-core Hartree–Fock studies of these cross sections so as to better understand the underlying shape resonant structure and the role of electronic relaxation in these processes. A broad shape resonance is observed in each of the core-hole cross sections at 10-20 eV kinetic energy and there is some evidence of a second shape resonance near the thresholds, an energy region which is not accessible experimentally. The cross sections also exhibit site-specific behavior with maxima at widely separated photoelectron kinetic energies. These differences probably arise from the fact that photoelectron matrix elements for different core orbitals probe different regions of the shape resonant orbital which extends over the entire molecule. Although the higher energy shape resonances appear quite similar, Hartree–Fock studies show that the central nitrogen resonance is more sensitive to effects of electronic relaxation than the terminal nitrogen or oxygen resonances. Large differences are also seen between the photoelectron asymmetry parameters for the central and terminal atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460514
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  • 8
    Electronic Resource
    Electronic Resource
    C 1s photoionization of H2CO and C2H4: An angle-resolved photoelectron study (1993)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 6735-6741 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We have measured partial photoionization cross sections σ and asymmetry parameters β of the C 1s main line and the π→π* shake-up satellites of the isoelectronic molecules formaldehyde and ethylene in the near threshold region. In all channels we observe a strong cross section enhancement and a decrease in the β parameter due to a shape resonance in the continuum. For each molecule the variation of σ and β with photoelectron kinetic energy is nearly identical for main line and satellites indicating only relatively small modifications of the effective molecular potential induced by the additional π→π* excitation. There are no indications of conjugate shake-up processes in either molecule.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.464765
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  • 9
    Electronic Resource
    Electronic Resource
    An angle-resolving photoelectron spectrometer for the simultaneous measurement of cross sections and asymmetry parameters using synchrotron radiation : Proceedings of the 4th international conference on synchrotron radiation instrumentation (1992)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 63 (1992), S. 1454-1457 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe an angle-resolving photoelectron spectrometer for atoms and molecules which uses the magic angle geometry in combination with multidetection such that cross sections and asymmetry parameters can be determined simultaneously. The instrument is based on the cylindrical mirror analyzer (CMA) design with the cylinder axis and the light beam collinear. Only the photoelectrons which are emitted in the "reverse'' direction at the magic angle reach the ring-shaped position-sensitive detector. The complete system also incorporates a conical effusive gas source, in order to maintain cylindrical symmetry, and very efficient differential pumping between target and electron spectrometer. Results from the C 1s photoionization of CO2 demonstrate the kind of precision attainable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1143041
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  • 10
    Electronic Resource
    Electronic Resource
    Optical emission from ultrathin strained type-II InP/GaP quantum wells (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 2886-2888 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe the growth and optical emission from ultrathin strained InP quantum wells grown on GaP substrates using gas-source molecular-beam epitaxy. The InP thickness was varied between 0.5 and 1.6 monolayers. Intense photoluminescence was emitted from the structures; time-resolved measurements indicate rather long carrier lifetimes of about 19 ns. With decreasing InP coverage, the emission lines are shifted from 2.18 to 2.28 eV due to quantum size effects. We explain the emission as spatially indirect recombination of electrons from the GaP X valleys with holes in InP and its phonon replicas. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1414291
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