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Digitale Medien

Source density analysis of scalp potentials during linguistic and non-linguistic processing of visual stimuli (1986)

MacKay, D. M. ; Ludwig, T. E.

Springer

Experimental brain research 64 (1986), S. 451-463

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ISSN: 1432-1106

Schlagwort(e): EEG ; Event-related potentials ; Linguistic processing ; Spatial perception ; Hemispheric lateralization ; Source-density analysis ; Cortical localization ; Vision

Quelle: Springer Online Journal Archives 1860-2000

Thema: Medizin

Notizen: Summary Event-related potentials (ERPs) were recorded from 40 locations, covering most of the scalp, during repeated tasks in which the observer (O) had to judge either the tense of a printed verb (V) or the symmetry of a spatial pattern (S). Stimuli were drawn at random from large ensembles. A simplified method of Laplacean analysis (MacKay 1983, 1984) allowed the corresponding source densities to be mapped at up to 28 locations, relatively free of artefacts due to eye movements or tongue movements. O signalled his judgment in each case by pressing one of two buttons on a given cue. The decision time allowed was kept short (about 1 s) but long enough for the task to be handled successfully. When stimuli ‘V’ and ‘S’ were drawn from geometrically different ensembles, the source-density distributions for the two tasks differed significantly at a number of locations. When ‘V’ and ‘S’ were drawn from a common ensemble, however, and O was instructed on each trial (in random order) to assess each stimulus as a word or as a geometrical pattern, the similarities in the source-density maps were more striking than the differences. It would seem that during sufficiently rapid verbal and spatial judgments, little sign of hemispheric specialization or task-specific differences may appear in the spatiotemporal profile of ERP source densities. More salient differences, some lateralized, appeared during the preparation interval prior to verbal and spatial tasks; but their pattern varied widely from subject to subject.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00340481

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Digitale Medien

Zur Phthaloylierung von CelluloseacetatenHerrn Professor Dr. Otto Vogl zur Vollendung des 60. Lebensjahres freundlichst gewidmet (1987)

Wagenknecht, W. ; Paul, D. ; Philipp, B. ; [weitere]

Weinheim : Wiley-Blackwell

Acta Polymerica 38 (1987), S. 551-554

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ISSN: 0323-7648

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Beschreibung / Inhaltsverzeichnis: The phthaloylation of partially substituted cellulose acetates by phthalic anhydride in acetone as the reaction medium was investigated. Special consideration is given to the influence of the original acetyl content and of the acylation catalyst on the course of reaction, as well as to the relations between course of reaction, phthaloyl-DS, and solubility of the products. The decrease in acetyl group content after phthaloylation is considered to be mainly due to splittingoff of acetyl groups during processing the reaction product and not to a transesterification reaction.

Notizen: Die Phthaloylierung partiell substituierter Celluloseacetate mit Phthalsäureanhydrid in Accton als Reaktionsmedium wurde untersucht. Besonders berücksichtigt werden dabei der Einfluß des Ausgangs-Acetylgehaltes und des eingesetzten Acylierungskatalysators auf den Reaktionsablauf, sowie der Zusammenhang zwischen Reaktionsablauf, Phthaloyl-DS und Löslichkeit der Produkte. Die Verringerung des Acetylgehaltes nach der Phthaloylierung wird in erster Linie auf eine Abspaltung während der Aufarbeitung und nicht auf eine Umesterung zurückgeführt.

Zusätzliches Material: 5 Tab.