Modification of Al-Si alloys: Microstructure,thermal analysis,and mechanisms

In aluminum-silicon cast alloys, the shapes of the silicon phase and the general solidification pattern can be changed by the cooling conditions and by minor additions to the melt. The minor additions either cause modification (sodium, strontium, and other metals) or refine the primary silicon in hypereutectic alloys (phosphorus and elements of Group V-B). Detailed examination of the modified microstructures and analysis of cooling curves are compatible with a modification mechanism involving growth rather than nucleation kinetics.     

Identification of material hardening parameters by three-point bending of metal sheets

Calibration of hardening and partly viscoplastic parameters of the previously published material model was the primary concern of this paper. The method used for identification of the material hardening parameters for metals, the three-point cyclic bending of sheets, constitutes a basis for this work. Plastic hardening parameters were determined by comparing load–displacement curves from FE simulations with those from the tests. Since viscoplasticity is assumed, stress–strain curves from uniaxial tension tests at selected strain rates for strain-rate sensitive materials were employed to calibrate corresponding viscoplastic parameters. The optimization problems are solved by means of a commercial optimization code, LS-OPT, using a response surface methodology. The objective is to minimize (by the least-squares method) the sum of the differences between measured and simulated loads. The material parameters were identified for two high-strength steel alloys (ZSte340 and DP600, strain-rate sensitive materials), and one aluminium alloy (AA5182).     

InAs/AlSb/GaSb resonant interband tunneling diodes andAu-on-InAs/AlSb-superlattice Schottky diodes for logic circuits

Integrated resonant interband tunneling (RIT) and Schottky diode structures, based on the InAs/GaSb/AlSb heterostructure system, are demonstrated for the first time. The RIT diodes are advantageous for logic circuits due to the relatively low bias voltages (~100 mV) required to attain peak current densities in the mid-10⁴ A/cm ² range. The use of n-type InAs/AlSb superlattices for the semiconducting side of Schottky barrier devices provides a means for tailoring the barrier height for a given circuit architecture. The monolithically integrated RIT/Schottky structure is suitable for fabrication of a complete diode logic family (AND, OR, XOR, INV)     

Gender differences in partner violence in a birth cohort of 21-year-olds: Bridging the gap between clinical and epidemiological approaches.

This study describes partner violence in a representative sample of young adults. Physical violence perpetration was reported by 37.2% of women and 21.8% of men. Correlates of involvement in severe physical violence differed by gender. Severe physical violence was more strongly associated with unemployment, low educational attainment, few social support resources, polydrug use, antisocial personality disorder symptoms, depression symptoms, and violence toward strangers for men than for women. Women who were victims of severe physical violence were more likely than men who were victims to experience symptoms of anxiety. The findings converge with community studies showing that more women than men are physically violent toward a partner and with clinical studies highlighting violence perpetrated against women by men with deviant characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Roger G. Barker and behavior settings: A commentary.

Observes that R. G. Barker's (see record 1981-04344-001) paper documents and illustrates his approach to science, his lifelong concern with environment–behavior relations, the major influences that have shaped his thought, and the utility of the behavior setting concept. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the "remembrance of things past": A longitudinal evaluation of the retrospective method.

Examined the extent of agreement between retrospective and prospective measures of variables in 7 different content domains: residence changes, anthropometrics, injuries, reading ability, family characteristics, behavior problems, and delinquency. Retrospective reports using data from a large sample of 18-yr-old youth who have been studied prospectively since their births were evaluated. The findings suggest that (1) psychosocial variables (e.g., reports about subjective psychological states and family processes) revealed the lowest level of agreement between prospective and retrospective measures and (2) even when retrospective reports correlated significantly with prospective data, the absolute level of agreement between the 2 data sources was quite poor. It appears that reliance on retrospective reports about psychosocial variables should be approached with caution. Moreover, it is suggested that the use of retrospective reports should be limited to testing hypotheses about the relative standing of individuals in a distribution and should not be used to test hypotheses that demand precision in estimating event frequencies and event dates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distributed call rerouting in multiclass broadband networks

Broadband integrated services digital networks (B-ISDN) must handle multiclass traffic with diverse quality of service requirements. We consider a multiclass routing model in which routes are calculated in a distributed fashion by the call originating nodes. Within this general context, we address the problem of rerouting a set of previously routed calls to avoid a failed link. Under the approach we propose, a single node executes an aggregate, global rerouting of all affected calls and then converts the set of aggregate routes into an allocation of bandwidth on each link to call origination nodes for the purpose of rerouting. The bandwidth allocation is distributed to each origination node, which in turn then calculates routes for the individual calls. The problem faced by each call origination node is a variant of the socalled bandwidth packing problem. We develop and analyze an approximate algorithm for solving this problem in the specific context that arises in our setting.The research was supported by IBM Corporation and by NSF Grant No. CDR-8803012.On personal leave from IBM RTP.     

Instability of signaling resolution models of parent-offspring conflict

Recent signaling resolution models of parent-offspring conflict have provided an important framework for theoretical and empirical studies of communication and parental care. According to these models, signaling of need is stabilized by its cost. However, our computer simulations of the evolutionary dynamics of chick begging and parental investment show that in Godfray's model the signaling equilibrium is evolutionarily unstable: populations that start at the signaling equilibrium quickly depart from it. Furthermore, the signaling and nonsignaling equilibria are linked by a continuum of equilibria where chicks above a certain condition do not signal and we show that, contrary to intuition, fitness increases monotonically as the proportion of young that signal decreases. This result forces us to reconsider much of the current literature on signaling of need and highlights the need to investigate the evolutionary stability of signaling equilibria based on the handicap principle.     

IQ and delinquency: A direct test of the differential detection hypothesis.

A number of studies have reported that juvenile delinquency is negatively related to IQ scores. The IQ/delinquency relation has been questioned on the basis of the differential detection confound, which attributes the apparent relaton to biased likelihood of detection, and thus inclusion in research, of low-IQ delinquents. A direct test of the differential detection hypothesis was conducted by comparing the mean IQ scores of two groups of delinquent subjects from the same birth cohort. Group 1 had been detected in delinquent acts by police. Group 2 was not known to police, but was equivalent to Group 1 on amount and seriousness of self-reported delinquency. The two groups did not differ significantly on IQ, but both groups scored significantly below nondelinquent cohort members. Results were inconsistent with the prediction of group differences posed by the differential detection hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The von Restorff effect in rats (Rattus norvegicus).

Two experiments examined the functional equivalence of memory in the rat (Rattus norvegicus) with memory in humans for serially presented items. Memory was assayed with an 8-arm radial maze, in which rats were allowed access to 5 arms of the maze and were then removed. Following a retention interval of 16 min, the rats were replaced in the maze and allowed to retrieve pellets from the 3 unvisited arms. The errors in reentering previously visited arms were noted. Both primacy and recency effects were found as with humans. Presenting a stimulus change after entry to 1 of the maze arms improved recall for that arm relative to when no change occurred. This effect was found using both handling and tone cues, and irrespective of whether the change consisted of presentation or nonpresentation of the cue. These results suggest that rats are subject to a von Restorff-like effect similar to that in humans. (PsycINFO Database Record (c) 2010 APA, all rights reserved)