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.     

Development of an enzyme-linked immunosorbent assay for measurement of serum-associated ALX40-4C

ALX40-4C is an antiretrovirus agent that has been found to have some inhibitory properties against human immunodeficiency virus (HIV) replication in vitro. The compound was designed as a competitor of the HIV Tat protein for TAR binding. In addition to its anti-HIV properties, it has demonstrated the ability to inhibit in vitro replication of herpes simplex virus types 1 and 2 as well as human cytomegalovirus. Subsequently, in vivo pharmacokinetic evaluation of ALX40-4C necessitated the establishment of a detection system for the measurement of ALX40-4C in subject serum. For this purpose, an indirect-competition enzyme-linked immunosorbent assay with generated rabbit anti-ALX40-4C antiserum was developed. The original assay took 12 h to complete and required many manipulations. Herein, we describe alterations to the system that resulted in the overall reduction in assay time and manipulation. We demonstrate that our alterations do not affect the specificity or sensitivity of the assay compared to that of the original system. ALX40-4C levels in spiked serum samples as well as drug levels from patient samples were used to validate the assay.     

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.     

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)     

Influence of interresponse time reinforcement on signalled-reward effect.

Examined the conditions under which presenting a signal for reinforcement decreases or increases the rate of leverpressing in rats. Response rate on a variable-interval (VI) schedule of reinforcement was decreased by a brief signal for reinforcement. In Experiment 1, requiring 1 short IRT to occur on completion of the VI requirement attenuated this response decrement. Requiring three responses to be emitted within a minimum amount of time at the end of the VI resulted in the reinforcement signal's enhancement of response rates. Experiment 2 replicated this increase in responding and showed that the reinforcement signal attenuated response rates on a simple VI schedule that yielded the same overall rate of reinforcement. In Experiment 3, the reinforcement signal enhanced response rates when 3 responses were required at the end of a VI schedule, but the signal attenuated response rates when the 3 responses could occur at any time in relation to the VI. These results suggest that the pattern of responding emitted immediately prior to reinforcement is a critical factor in determining the effect of reinforcement signal on response rate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

High-strain-rate superplasticity in aluminum-matrix composites

Recent progress in high-strain-rate superplastic forming of aluminum metal-matrix composites has highlighted the potential of these materials for the mass production of complex shapes. This article reviews the current scientific understanding of this subject and identifies the areas where future work is needed to develop the technology to the manufacturing stage.