Eye Movements Affect Postural Control in Young and Older Females

Visual information is used for postural stabilization in humans. However, little is known about how eye movements prevalent in everyday life interact with the postural control system in older individuals. Therefore, the present study assessed the effects of stationary gaze fixations, smooth pursuits, and saccadic eye movements, with combinations of absent, fixed and oscillating large-field visual backgrounds to generate different forms of retinal flow, on postural control in healthy young and older females. Participants were presented with computer generated visual stimuli, whilst postural sway and gaze fixations were simultaneously assessed with a force platform and eye tracking equipment, respectively. The results showed that fixed backgrounds and stationary gaze fixations attenuated postural sway. In contrast, oscillating backgrounds and smooth pursuits increased postural sway. There were no differences regarding saccades. There were also no differences in postural sway or gaze errors between age groups in any visual condition. The stabilizing effect of the fixed visual stimuli show how retinal flow and extraocular factors guide postural adjustments. The destabilizing effect of oscillating visual backgrounds and smooth pursuits may be related to more challenging conditions for determining body shifts from retinal flow, and more complex extraocular signals, respectively. Because the older participants matched the young group's performance in all conditions, decreases of posture and gaze control during stance may not be a direct consequence of healthy aging. Further research examining extraocular and retinal mechanisms of balance control and the effects of eye movements, during locomotion, is needed to better inform fall prevention interventions

Predictors of social competence in middle childhood: Discriminating between peer status groups

The purpose of the study was to determine the relative importance of multiple variables in predicting social competence in middle childhood, as defined by peer status groups. In addition, the study sought to determine how effective the combination of variables were in predicting peer status group membership. Peer status is considered an operational measure of social competence and was used as the criterion variable. The peer status groups generated via sociometric nomination measures were popular, rejected, neglected, and average. The predictor variables in this study were academic achievement, social goals, self-perception, sibling warmth, and parenting style. Participants were 216 third- and fourth-grade students. All participants completed the nomination based sociometric measures and self-report measures assessing four predictor variables. Academic achievement data were independently collected by the researcher via student report cards. Separate logistic regressions were conducted for each status group and the set of predictor variables. A discriminant function analysis was conducted with all status groups and the set of predictor variables. Results indicated that academic achievement was consistently the best predictor of peer status, with self-perception and authoritarian parenting (only for participants with siblings), also providing significant levels of predictive utility. These variables were found to best differentiate children rejected by their peers from the rest of the sample

An Integration Rule Processing Algorithm and Execution Environment for Distributed Component Integration. Informatica 30:193–212

The Integration Rules (IRules) Project * provides an active, rule-based approach for supporting eventdriven activity in applications involving distributed software component integration. This paper presents the execution model, transaction model, and integration rule execution algorithm of the IRules environment. The paper begins with an overview of the IRules language framework to establish the context for the use of events and rules in the integration process, with Enterprise JavaBeans (EJBs) serving as a component model. The paper then elaborates on the integration rule processing algorithm and execution environment. The rule execution model supports traditional active rule coupling modes, and defines a new immediate asynchronous mode to support concurrent execution of triggered rules and transactions. The transaction model is based on the flexible transaction model, providing a means to coordinate global transaction execution with the transactional features of EJB containers. IRules component wrappers also provide support for the global transaction context as well as the synchronization of method execution with the nested execution of integration rules. The paper defines the semantics of coupling modes in terms of cycles and levels of rule execution, presenting the integration rule processing algorithm for coordinating the execution of events and methods on components with the nested execution of integration rules in the context of the transaction model. Th

An Event Processing System for Rule-Based Component Integration

Abstract: The Integration Rules (IRules) project has developed an environment in which active rules, known as integration rules, are used together with transactions to provide an event-driven, rule-based approach to the integration of black-box components. This paper presents the event processing system that supports the use of integration rules over components. The event processing system is composed of the language framework for the specification of different types of events, an event generation system for generating event instances, and an event handler for communicating the occurrence of events to the integration rule processor. The language framework supports the enhancement of EJB components with events that are generated before and after the execution of methods on components. Since integration rules support an immediate coupling mode and execute in the context of nested transactions, a synchronization algorithm has been developed to coordinate the execution of immediate integration rules with the execution of methods on components. The synchronization algorithm makes it possible to suspend and resume distributed application transactions to accommodate the nested execution of integration rules with an immediate coupling mode.

A Language and Framework for Supporting an Active Approach to Component-Based Software Integration

distributed, black-box software components. The goal of IRules is to provide an environment in which an application is developed through the integration of software components using active rules that are known as integration rules. Using the IRules Component Definition Language (CDL), the application integrator first describes a purchased, black-box component within the IRules environment to allow access to the properties and methods defined by the purchased component. In addition, CDL allows for the definition of named extents, stored and derived attributes, externalized relationships and events to enhance the features of the purchased components to support application development. After defining the desired interface for the component, the application integrator then develops the application using active integration rules that define the interaction of the components in response to events. This paper presents the Component Definition Language and its resulting framework that supports the IRules active approach to component-based software integration.