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  • 1
    Electronic Resource
    Electronic Resource
    Larger topographical variance and decreased duration of brain electric microstates in depression (1995)
    Springer
    Journal of neural transmission 99 (1995), S. 213-222 
    Details
    ISSN: 1435-1463
    Keywords: Electroencephalography ; space-oriented segmentation ; depression ; thought disorders
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The topographical configuration of the spontaneous brain electric fields is considered to contain relevant information about the pattern of the generating cortical electrochemical activation and the associated cognitive processes. Space oriented segmentation allows to break down the stream of the spontaneous EEG into brain electric microstates with stable configuration of the fields. It has been shown that the mean duration of the microstates was consistent with the duration of elementary steps of cognitive processes, and that different topographies of the microstates are associated with different cognitive modalities. Space-oriented segmentation was applied to the resting EEG of 22 depressive patients and of 22 controls. The topographical variance was larger, and the most prominent brain electrical microstates of the EEG epochs were significantly shorter in the depressive group than in controls. No differences were found for the shortest microstates. This result cannot be explained by group differences in the frequency domain of the EEG. No topographical differences were found between the microstates of depressives and those of controls. Based on previous results in healthy volunteers during spontaneous cognition and in schizophrenic patients, the findings indicate that formal aspects rather than the modalities of the stream of cognition are altered in depression. Automatic and schematic processing, and attentional deficits as described in depressive patients might account for the finding of less sustained brain electrical microstates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01271480
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  • 2
    Electronic Resource
    Electronic Resource
    Age, geodynamic setting, and mantle enrichment processes of a K-rich intrusion from the Meissen massif (northern Bohemian massif) and implications for related occurrences from the mid-European Hercynian (1997)
    Springer
    Geologische Rundschau 86 (1997), S. 556-570 
    Details
    ISSN: 0016-7835
    Keywords: Key words K-rich rock ; Amphibole ; 40Ar/39Ar laserdating ; Mantle enrichment ; Moldanubian ; Post-collisional intrusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  The plutonic complex of the Meissen massif (northern margin of the Bohemian massif) comprises dioritic to mainly monzonitic and granitic rocks. The diorite to monzonite intrusions show major and trace element patterns typical for shoshonitic series. The chemical signatures of less crustally contaminated diorites are similar to arc-related shoshonitic rocks derived from continental lithospheric mantle (CLM) sources previously enriched by subduction of altered oceanic crust. Laser step heating 40Ar/39Ar analyses on actinolitic to edenitic amphiboles from geographically different occurrences of the monzonitic intrusion yielded concordant plateau ages as well as total gas ages ranging from 329.1±1.4 to 330.4±1.4 Ma and from 330.4±2.1 to 330.6±1.8 Ma, respectively. These cooling ages are indistinguishable from sensitive highresolution ion microprobe (SHRIMP) 238U/206Pb intrusion ages measured on magmatic zircon rims from the monzonite (Nasdala et al., submitted). This shows that the monzonite intrusion is probably not related temporally to active subduction because it postdates eclogites of the adjacent Saxonian Erzgebirge by approximately 20 Ma. The shoshonitic magmas intruded during strike-slip tectonism along the Elbe valley zone. The enrichment of their mantle sources may be of Upper Devonian/Lower Carboniferous age or older. Intrusions of shoshonitic to ultra-potassic (K-rich) rocks during the Upper Visean/Namurian are widespread in the Moldanubian zone. Based on similar ages and structural relationships a similar post-collisional setting to the Meissen shoshonitic rocks can be demonstrated. Most of these occurrences cut high-grade nappe units which were subducted during the Upper Devonian/Lower Carboniferous. In contrast to the Meissen massif, at least the ultra-potassic members of the Central and the South Bohemian batholiths were derived from CLM sources enriched by fluids or melts released from subducted oceanic crust and by greater portions of crustal material. Despite the similar post-collisional geodynamic setting of the K-rich intrusions, different enrichment processes generated mid-European Hercynian CLM sources with heterogeneous major and trace element and isotopic signatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310050163
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    Paper (German National Licenses)
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