The effect of temperature and strain rate on the tensile strength of a fast-gas-cooled uranium-2 wt% molybdenum alloy

Tensile tests have been performed at strain rates from 10^?4 to about 2000/s and temperatures from ambient to +250°C on a uranium-2 wt% molybdenum alloy which had been aged for 2 h at 500°C after a fast gas cool from the γ-phase at a controlled rate of 40°C/min. Stress-strain curves are presented and the effect of strain rate and temperature on the flow stress, the ultimate tensile stress and the elongation to fracture is determined. A thorough structural characterisation of the specimen material, using X-ray analysis and scanning and transmission electron microscopy, allows the mechanical response to be related to the microstructural state of the material. Flow stress data at different temperatures and strain rates are analysed in terms of the theory of thermally activated flow and estimates made of the various activation parameters.     

Visual short-term memory: A methodological caveat.

Reports that estimates of decay time for nonverbal short-term visual memory varied from less than 3 sec to beyond 30 sec in a same-different matching task with 10 male right-handed undergraduates, depending on the physical similarity between target and comparison stimuli. The more dissimilar the stimuli, the higher the memory score at all delays and the slower the decline in performance over time. Findings draw attention to the obvious but commonly neglected point that generalizations concerning the duration of visual short-term memory, particularly as measured by recognition tests, should be routinely based on a psychophysical approach in which various task conditions are systematically varied along with retention interval. Incidental to the main point, results also suggest that decay functions may reflect a decline in accessibility rather than a complete loss of availability of memory traces. (French summary) (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concreteness-dependent associative priming: Separate lexical organization for concrete and abstract words.

Four experiments used associated, unrelated, and neutral ({blank}–word) pairs that varied on prime and target concreteness. In Experiment 1, associated targets were named faster than neutral targets when primes and targets were homogeneous for concreteness (i.e., concrete–concrete or abstract–abstract), but not when they were heterogeneous (i.e., concrete–abstract or abstract–concrete). Experiments 2 and 3, using lexical decision, showed priming for all pairs irrespective of prime and target concreteness. In Experiment 4, the prime was presented for 16.7 ms, followed immediately by a 168-ms random letter mask. Lexical decision times showed priming similar to that in Experiment 1. If priming in Experiments 1 and 4 reflected lexical processes, whereas priming in Experiments 2 and 3 entailed postlexical processes, then lexical processes may be functionally distinct for concrete versus abstract words. These findings are more consistent with dual-coding than common-coding explanations of concreteness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)