HLA_ACTOR_REPAST: An approach to distributing RePast models for high-performance simulations

RePast is a popular agent toolkit with proven capabilities to fulfil the modelling challenges of large multi-agent systems (MASs). The toolkit, though, is normally used on a standalone workstation and therefore its practical use can be constrained (in space and time) by the limited available computing resources. This paper proposes an original approach – HLA_ACTOR_REPAST – aimed to distributing RePast models for high-performance simulation of complex scalable models. Novel in HLA_ACTOR_REPAST is an exploitation of a lean actor infrastructure implemented in Java. Actors bring to RePast agents such features as migration, location-transparent naming, efficient communications, and a control-centric framework. Actors can be orchestrated by an in-the-large custom control structure which is in charge of ensuring the necessary message causality constraints. Distribution and time management concerns depend on the IEEE standard HLA middleware. The paper first discusses details of the software engineering process underlying the development of HLA_ACTOR_REPAST. The mapping techniques, assisted by Java text annotations and aspect-oriented programming, try to minimize “code intrusions” in the original model and favour model transparency. The paper then furnishes some experimental data which witness the good performance results achieved by applying HLA_ACTOR_REPAST to a distributed version of a classic MAS benchmark model.     

Matrix-Based Discrete Event Control for Surveillance Mobile Robotics

This paper focuses on the control system for an autonomous robot for the surveillance of indoor environments. Our approach proposes a matrix-based formalism which allows us to merge in a single framework discrete-event supervisory control, conflict resolution and reactive control. As a consequence, the robot is able to autonomously handle high level tasks as well as low-level behaviors, solving control and decision-making issues simultaneously. Moreover, the matrix-based controller is modular and can be easily reconfigured if mission characteristics or robot hardware configuration change. An illustrative example and a report on experimental investigations are provided to illustrate the main features of the proposed approach.     

Relationship of personal-social variables to belief in paternalism in parent caregiving situations.

Paternalism in family caregiving may jeopardize the older persons' autonomy; it needs to be better understood. Study objectives were to determine the relationship of belief in paternalism to personal–social characteristics and to determine the relative importance of these variables as predictors of belief in paternalism. Forty-six pairs of daughters (age 49.7) and mothers (age 77.7) were measured on belief in paternalism, dogmatism, attitude toward elders, affective feelings toward the other, and background and caregiving variables. Among both mothers and daughters, dogmatism and attitude toward elders were related to belief in paternalism; daughters' affective feelings was also related. Caregiving variables were unrelated, and demographic background was important only for daughters. Attitude toward elders was the strongest predictor. Results were interpreted in terms of a traditional family ideology. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feelings of attachment to siblings and well-being in later life.

On the basis of an adult model of sibling attachment, I hypothesized that the well-being of older persons depends on their perception of the closeness of the sibling bond, on their perception of any disruption of that bond, and on the sex combination of the siblings being considered. In all, 83 persons, aged 61 to 91 years, were interviewed about their relationships with each of their living siblings. They rated their feelings of closeness, conflict or rivalry, and indifference to the sibling. A measure of depression was used as the indicator of well-being. Separate correlational analyses were carried out for the four sex combinations of siblings. Closeness of the bond to a sister (by both men and women) was related to less depression. Also, women's perceptions of conflict and indifference in their relationships with sisters were related to increased depression. Findings are interpreted in terms of attachment theory and sex role expectations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sibling structure and intellectual ability.

Compared 3 sets of sibling structure variables derived from the theoretical approaches of K. Marjoribanks and H. J. Walber, R. B. Zajonc and G. B. Markus, and V. G. Cicirelli (see PA, Vol 54:9708; Vol 53:9290; and Vol 55:6726, respectively) as predictors of the child's intellectual ability. Ss were 603 11–12 yr olds. Regression analyses for the total group indicated that the sibling structure variables proposed seem to have only a weak relationship to measured intelligence of these Ss, even though the decline of mean intelligence with family size represented a greater magnitude of change than that reported by L. Belmont and F. A. Marrolla (1973). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A measure of caregiving daughters' attachment to elderly mothers.

Although attachment to a parent in adulthood remains a controversial topic, a measure is needed to assess the strength of adult daughters' current attachment to their elderly mothers. Representing 4 domains of the attachment concept (seeking security or comfort, distress upon separation, joy upon reunion, and feelings of love), a 16-item Adult Attachment Scale was developed and field-tested. Internal consistency reliability (alpha) was .95, and 1-year stability was .73. Some evidence for the validity of the measure is presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Caregiving decision making by older mothers and adult children: Process and expected outcome.

Dyadic caregiving decision making was studied in 30 mother-son and 29 mother-daughter pairs (mother's age = 65-94 years) who responded to a vignette depicting a caregiving decision situation. The observed decision-making process of mother-child pairs was largely naturalistic, with few alternatives proposed and quick convergence to a decision followed by a postdecision justification; a degree of more rational decision making was seen in some pairs. Among significant findings, adult children, especially sons, dominated the decision process, doing more talking and introducing more alternatives than did their mothers, who played a more subordinate role. Mother-son pairs expected more negative outcomes and greater regrets regarding their decisions than mother-daughter pairs. Closeness of the parent-child relationship influenced the decision-making process, expected outcomes, and regrets. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficient environment management for distributed simulation of large‐scale situated multi‐agent systems

Multi‐agent systems have been proven very effective for the modelling and simulation (M&S) of complex systems like those related to biology, engineering, social sciences and so forth. The intrinsic spatial character of many such systems leads to the definition of a situated agent. A situated agent owns spatial coordinates and acts and interacts with its peers in a hosting territory. In the context of parallel/distributed simulation of situated agent models, the territory represents a huge shared variable that requires careful handling. Frequent access by agents to territory information easily becomes a bottleneck degrading system performance and scalability. This paper proposes an original approach to modelling and distributed simulation of large‐scale situated multi‐agent systems. Time management is exploited for resolving conflicts and achieving data consistency while accessing the environment. The approach allows a simplification of the M&S tasks by making the modeller unaware of distribution concerns while ensuring the achievement of good scalability and performance during the distributed simulation. Practical aspects of the approach are demonstrated through some modelling examples based on Tileworld. Copyright © 2014 John Wiley & Sons, Ltd.     

Elders' end-of-life decisions: implications for hospice care

Elders' views on various end-of-life decision options were studied to determine each option's acceptability if they were faced with the need for such decisions. 388 black and white elders aged 60 to 100 responded to 17 decision scenarios depicting situations with a low quality of life, rating acceptability of each of 7 options for each scenario. Based on factor analysis of responses over scenarios, three scores were computed: maintaining life, ending life, and letting others decide. Profile types were identified and related to demographic background and personality variables. Implications for hospice care are drawn.