Speed limits: Orientation and semantic context interactions constrain natural scene discrimination dynamics.

The visual system rapidly extracts information about objects from the cluttered natural environment. In 5 experiments, the authors quantified the influence of orientation and semantics on the classification speed of objects in natural scenes, particularly with regard to object-context interactions. Natural scene photographs were presented in an object-discrimination task and pattern masked with various scene-to-mask stimulus-onset asynchronies (SOAs). Full psychometric functions and reaction times (RTs) were measured. The authors found that (a) rotating the full scenes increased threshold SOA at intermediate rotation angles but not for inversion; (b) rotating object or context degraded classification performance in a similar manner; (c) semantically congruent contexts had negligible facilitatory effects on object classification compared with meaningless baseline contexts with a matching contrast structure, but incongruent contexts severely degraded performance; (d) any object-context incongruence (orientation or semantic) increased RTs at longer SOAs, indicating dependent processing of object and context; and (e) facilitatory effects of context emerged only when the context shortly preceded the object. The authors conclude that the effects of natural scene context on object classification are primarily inhibitory and discuss possible reasons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prof. Dr.-Ing. Dr. h. c. Franz Kollmann Zum 65. Geburtstag

Ohne Zusammenfassung     

An electrophysiological study of the insertion of overt response choice.

Using electrophysiological measures, the authors studied changes in prestimulus state, stimulus identification, and response-related processing when, in a go/no-go task, forced choice between 2 overt go responses was inserted. The authors observed decreased prestimulus motor preparation (electromyogram), no change in stimulus identification time (selection negativity), a minor increase in response selection time (lateralized readiness potential), a large increase in response preparation time (lateralized readiness potential), a minor effect on response execution time (electromyogram), and a decrease in the activation of a response-inhibition process on no-go trials (frontal event-related potential). The existence of the response-inhibition process was verified by the presence of inverted lateralized readiness potentials on no-go trials. Pure insertion of response choice in a task seems impossible because the choice between activation and inhibition (go/no-go) always seems already present. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lateralized processing of speech prosodies in the temporal cortex: a 3-T functional magnetic resonance imaging study

Prosodic modulation of speech provides information about emotional states of speakers (affective prosodies) or serves as syntactic markers to change linguistic aspects of speech (linguistic prosodies). Previous electrophysiological investigations and studies on patients with right or left hemisphere damage showed nonuniform results with respect to lateralization of prosodic processing. In this study 20 healthy right-handed volunteers were investigated with functional magnetic resonance imaging of the acoustically responsive areas on the supratemporal plane while detecting phonemes as control targets or prosodies in strings of nonsense syllables and adjectives, the latter randomly intonated in a declarative, interrogative, commanding, happy, or sad fashion. In control task A the phoneme /a/ was detected in the syllables. In control task B the phoneme /a/ was detected in the adjectives, and in the experimental task C the sad intonations (affective) and in the experimental task D the interrogative intonations (linguistic) had to be detected in the same material. In task A intensity-weighted volumes of activated voxels were not different in the two hemispheres (laterality index 0). In task B with an irrelevant phoneme detection with respect to prosodic material, the population split into two subgroups with similar right or left hemispheric lateralization of activity leading to an absolute laterality index of 26.8 across all subjects. During detection of affective prosodies (task C), lateralization was maintained yet the absolute laterality index reduced to 14.5, while there was no lateralization during detection of linguistic prosodies. The sum of activations in the two hemispheres was the same across all tasks and subgroups, which suggests that the lateralizations occurring with presentation and detection of prosodic material depend on a redistribution of activity between hemispheres.     

Die Bedeutung des Bruchverhaltens hochfester Stähle für ihre Verwendung

Kennzeichnende Beispiele hochfester Stähle. Bedeutung des Bruchverhaltens für den Einsatz dieser Stähle im Vergleich mit Stählen geringerer Festigkeit. Zahlenmäβige Erfassung der Riβausbreitungsgeschwindigkeit mit Hilfe der Bruchzähigkeii. Theoretische Herleitung der Bruchzähigkeii mittels der Bruchmechanik. Einfluβ eines korrosiven Mediums bei statischer Belastung und einer Schwingungsbeanspruchung auf die Riβausbreitungsgeschwindigkeit. Beispiel des Stahles X 2 NiCoMo 18 8 5.     

Absorber material cladding chemical interaction in vented fast breeder reactor absorber pins. B4C/stainless steel chemical interaction in sodium environment and effect of metallic Nb and Cr4 layers

Out-of-pile tests were performed to study the chemical interaction between B₄C and cladding material (stainless steel) in sodium environment as components of a “Fast Breeder” absorber pin. The results of isothermal capsule tests (873–1073 K and 750–8600 h) show a chemical attack on the cladding. The penetration depth amounted to 50 microns within one year at 873 K and increased parabolically in the course of time. The test results indicate that diffusion of boron through the reaction layer is determinative for the kinetics of chemical interaction. Carbon diffusion is inhibited by the formation of metal boride layers. Metallic niobium or chromium layers on the inner surface of the cladding material reduce definitely the process of boronation. The tests show that chemical interaction in the B₄C-Na-stainless steel system is sufficient low at conditions foreseen for high absorber pins in SNR-300 reloads and SNR-2.     

Die martensitischen Umwandlungen in kohlenstoffarmen austenitischen Chrom-Nickel-Stählen

Dilatometrische, röntgenographische, metallographische und magnetische Untersuchung über die Umwandlung von metastabilem Austenit bis —196 °C in 19 Stählen mit rd. 0,05% C, 7,3 bis 22,4% Cr, 2,6 bis 17,9% Ni und geringen Gehalten an den üblichen Begleitelementen von Stahl. Aufstellung eines martensitischen Umwandlungsschaubildes in Abhängigkeit vom (Cr + Ni)-Gehalt mit einem Tripelpunkt. Metallographische Unterscheidung von γ, ? und α_? im Feingefüge und im Oberflächenrelief. Vergleich des martensitischen Umwandlungsschaubildes der Chrom-Nickel-Stähle mit dem der Manganstähle. Herkunft der ?-Phase.