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  • 1
    ISSN: 1432-0533
    Schlagwort(e): Human rabies ; Negri bodies ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Light-and electron-microscopical studies were conducted on necropsy material from six cases of rabies encephalitis including three with the unusual feature of surviving for over 14 days as a result of intensive medical care. This included administration of antiviral agents and interferon inducers and prevention of hypoxia by intermittent positive pressure ventilation. In all these cases, typical Negri bodies were demonstrated. Inflammatory reaction was absent or minimal. Unlike the cases with short survival where Negri bodies were infrequently seen and restricted mostly to the hippocampus, in cases with prolonged survival, they were present in large number, widely distributed throughout the grey matter of the brain. The associated inflammatory reaction in these cases, however, did not keep pace with the increase in number of inclusion bodies. Peripheral neuritis was observed in two of these cases, which also showed myelitis involving the cervical region and inflammation of dorsal root ganglia. One of them showed necrosis and severe inflammation of the lower cervical sympathetic ganglion. An electron-microscopical study conducted in four cases showed three forms of the inclusion body in the cytoplasm of neurons.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 79 (1990), S. 456-460 
    ISSN: 1432-0533
    Schlagwort(e): Rosenthal fibers ; Immunohistochemistry ; Ultrastructure ; Neoplastic and reactive astrocytes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The nature of Rosenthal fibres (RF) was investigated in eight cases each of low-grade astrocytoma and reactive gliosis using immunohistochemical (IH) staining for glial fibrillary acidic protein (GFAP), electron microscopy (EM) and immunoelectron microscopy (IEM) by immunogold labelling technique. By IH under light microscopy (LM), three types of RF were seen, uniformly positive (type I), rim positive (type II) and completely negative (type III). EM showed variation in structural pattern of RF. Some RF contained large amount of glial filaments (GF) intermingled with RF while others with a large amount of electron dense material and less GF. Thus, the presence and amount of GF in RF appear to be responsible for the different types of IH staining under LM. IEM showed that all RF including the ones consisting of entirelh amorphous material possess immunoreactivity for GFAP. It is suggested that RF formation is a two-stage process, staring with excessive accumulation of GF within astrocytic processes followed by their gradual alteration into electron-dense amorphous material under the influence of some unknown metablic or other factors. The quantitative analysis of different types of RF suggests a difference in the rate of formation of RF in neoplastic and reactive conditions.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 48 (1989), S. 437-443 
    ISSN: 1432-0630
    Schlagwort(e): 85.30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract Computer studies have been made on the high frequency characteristics of symmetrically doped flat profile double drift region (DDR) InP and GaAs impatts in the mm-wave (60–100 GHz) frequency band. The spatial distribution of high frequency negative resistance and reactance in the depletion layer of DDR devices and their admittance properties have been investigated. The results indicate that DDR InP impatts should have higher drift zone voltage drop, higher negative resistance and higher negative conductance compared to their GaAs counterparts designed for the same range of mm-wave frequencies. Furthermore, the negative resistance peak is larger in magnitude for InP impatts compared to that for GaAs impatts. It is thus observed that DDR InP impatts should be superior to their GaAs counterparts as regards mm-wave power generation with high conversion efficiency.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    ISSN: 1432-0630
    Schlagwort(e): 85.30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract High-frequency analysis has been carried out to predict the rf performance of 〈111〉, 〈110〉 and 〈100〉 oriented p + nn +, n + pp + (single drift region) and n + npp + (double drift region) GaAs IMPATT diodes for opertion at 35 and 60 GHz. The microwave performance is observed to be highly sensitive to crystal orientation in case of p + nn + and n + npp + diodes whereas orientation of the substrate has negligible effect on n + pp + avalanche diodes. The calculation shows that 〈111〉 oriented GaAs IMPATT diode would provide the largest magnitude of negative resistance and negative conductance for both SDR p + nn + and DDR n + npp + diodes which indicates that high microwave power with high conversion efficiency can be realised from these 〈111〉 oriented GaAs devices. This result can be explained from the experimental data of electron and hole ionization rates for different orientations in GaAs.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    ISSN: 1432-0630
    Schlagwort(e): 85.30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract The effect of mobile space charge on avalanche zone width and conversion efficiency of single drift region (SDR) indium phosphide impatts at 12 and 60 GHz has been investigated. The results show thatp +nn+ InP diodes have a narrower avalanche zone and a higher conversion efficiency compared ton +pp+ diodes for both the frequencies at normal operating current densities. The expansion of avalanche zone and efficiency degradation at high current levels are more pronounced inp +nn+ at 12 GHz and inn +pp+ at 60 GHz.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Applied physics 56 (1993), S. 575-580 
    ISSN: 1432-0630
    Schlagwort(e): 85.30
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Maschinenbau , Physik
    Notizen: Abstract A generalized small-signal computer simulation of double avalanche region (DAR) n +-p-v-n-p + Si and InP IMPATT diodes has been carried out for different frequencies and current densities taking both drift and diffusion of charge carriers into account. The simulation results show that both symmetrically and asymmetrically doped devices based on Si and InP exhibit discrete negative conductance frequency bands separated by positive conductance frequency bands. The magnitudes of both negative conductance and negative resistance of InP devices are larger than those of Si devices in case of symmetrical and asymmetrical diodes. Further, the negative resistance profiles in the depletion layer of these diodes exhibit a single peak in the middle of the drift layer in contrast to double peaks in double drift region diodes.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 41 (1978), S. 169-171 
    ISSN: 1432-0533
    Schlagwort(e): Pituitary gland ; Oncocytic adenoma ; Ultrastructure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Two cases of oncocytic adenoma occurring in the pituitary are reported. Both were men aged 40 and 50 years respectively and there was no evidence of endocrine abnormality. In both the tumours many cells showed abundant acidophilic finely granular cytoplasm which had not stained positively with PAS-orange G stain. Electron microscopically the cells contained numerous mitochondria associated with marked reduction of other cytoplasmic organelles including the secretory granules.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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