Mean square consensus of double-integrator multi-agent systems under intermittent control: A stochastic time scale approach

We consider the leader–follower consensus problem for a multi-agent system where information is exchanged only on a non-uniform discrete stochastic time domain. For a second-order multi-agent system subject to intermittent information exchange, we model the tracking error dynamics as a $\mu ?$varying linear system on a discrete stochastic time scale, where μ is the graininess operator. Based on a Lyapunov operator and a positive perturbation operator on the space of symmetric matrices, we derive necessary and sufficient conditions to design a decentralized consensus protocol. This protocol allows us to cast the mean-square exponential consensus problem within the framework of dynamic equations on stochastic time scales. We establish some theoretical results which allow for the computation of the control gain matrix which guarantees the mean-square exponential stability with a given decay rate for the error dynamics. To show the effectiveness of the theoretical results, some simulation and experimental results on multi-robot systems have been performed.     

Child and adolescent abuse and subsequent victimization: a prospective study

OBJECTIVE: We investigated the possible reciprocal relationship between victimization experiences and psychological functioning by assessing abuse experiences in childhood, adolescence, and during a 2-month follow-up period. METHOD: At the beginning of the study (Time 1), abuse histories, trauma and depressive symptoms, and interpersonal functioning were assessed in 551 college women. Subsequent victimization experiences and psychological outcomes were assessed at the follow-up (Time 2). RESULTS: Path analyses indicated that verbal abuse by the mother and father were predictive of various psychological outcomes as measured at Time 1 and emerged as the only significant predictors of adolescent dating violence. Adolescent dating violence subsequently predicted the experience of dating violence during the 2-month follow-up period. Paternal physical abuse predicted adolescent sexual victimization which subsequently predicted all symptom measures at Time 1. Conversely, the experience of adolescent physical dating violence was not predictive of any of the symptom measures at Time 1. For those women who experienced dating violence during the follow-up, however, the severity of their abusive experiences was related to both depression and interpersonal problems assessed at Time 2. In comparison, for those women who experienced sexual victimization during the follow-up period, the severity of their abusive experiences was related to trauma symptoms. Interpersonal problems emerged as both an aftereffect of adolescent sexual victimization experience and a predictor of a subsequent sexual victimization experience during the follow-up. CONCLUSIONS: Given that emotional abuse emerged as a predictor of adolescent dating violence and psychological outcomes, researchers and clinicians need to continue to explore this problem. Further, it is important to assess how interpersonal problems contribute to the risk of subsequent sexual victimization and to try to break the cycle between adolescent abuse experiences and subsequent physical and sexual assaults.     

The impact of a dialogic reading program on deaf and hard-of-hearing kindergarten and early primary school-aged students in Hong Kong

The present study investigated the effects of a special interactive dialogic reading method developed by Whitehurst et al. (1988) on deaf and hard-of-hearing children in Hong Kong. Twenty-eight deaf and hard-of-hearing children in kindergarten, first, or second grade were pretested on a receptive vocabulary test and assigned to one of three conditions, dialogic reading, typical reading, and control, with age and degree of hearing loss matched. After an 8-week intervention, the children were re-tested. The dialogic reading group had a significantly greater improvement in vocabulary scores than did the other two groups. Parent-child interactions of high quality and the use of pictorial materials are likely the key successful factors in the program. The educational value of this intervention is discussed.     

Netskills and the current state of beliefs and practices in student learning: an assessment and recommendations

This article analyses data from over 1000 student questionnaires dealing with how students currently use the web to support their learning. It discusses student understanding, needs, and expectations of the web and the overwhelming perception that the web now forms an integral part of their study and research practices. However, these practices require greater definition and refinement for and by the student. Evidence from some teaching staff is compared with that from students for validation purposes and has also revealed striking differences in perception and attitudes between the two groups. We identify specific needs on the part of most students in our survey who require greater guidance and study skills when using the web. These “Netskills” are described and recommendations are made concerning their acquisition and future development by students who are demanding that such skills become part of their own learning strategies.     

Get real: making problematic the pathway into the teaching profession

Learning to be a teacher is a complex and very personal matter that involves transformation from student teacher (pre‐service teacher) to teacher. The pathway to being a teacher is scattered with what appears to be competing tensions in various realities. This paper explores those tensions and realities through the context of two final year integrated field‐ and campus‐based subjects that all pre‐service teachers undertake as they complete their four‐year teacher education journey into the primary (ages 5‐ to 12‐years‐old) teaching profession. We then propose a framework involving a variety of realities that pre‐service teachers face through the recognition and resolution of the tensions these pre‐service teachers experience in the workplace.     

Quality Learning of Physics: Conceptions Held by High School and University Teachers

This paper reports an exploration of the conceptions of quality learning held by two samples of physics teachers – final year, high school physics teachers and academics teaching first year university physics. We begin by outlining our view of quality learning, that is a view of learning in which learners take control of their own learning and engage with active construction and reconstruction of their own meanings for concepts and phenomena. This view of quality learning recognises the crucial role of the affective dimension of learning on the extent to which students engage with and maintain such constructivist and metacognitive approaches to learning. The study explored the qualitatively different ways in which individuals conceptualise quality learning in physics, using semi structured interviews that explored aspects of learning that the respondents regarded as worth fostering in their classrooms. The interview approach was a modification of the Interview-About-Instances approach that allowed the possibility of interviewees suggesting instances of particular relevance to their view of quality learning. This process resulted in a considerable quantity of rich and complex data related to a large range of aspects of physics learning. These data are summarised here, and the qualitatively different conceptions of the respondents with respect to four significant aspects of physics learning are discussed. These aspects are: doing experimental work; linking physics to the real world; students taking responsibility for their own learning and being confident/feeling proud of what you can do.     

Using an analogy to model causal mechanisms in a complex text

Two experiments examined the role of analogy inthe development of a situation model of atarget passage. Specifically, we examinedwhether an analogous source text could improvecomprehension and inferencing about causalmechanisms in the target. An ``analogy group'studied a fictional pseudo-scientific passageunder the guidance of an analogous passage(also fictional) which shared causal structureswith the target. A ``statement group' studiedthe target under the guidance of an abstractstatement that characterized the target causalstructures. A ``target-only group' received noadditional material. All groups received tasksthat assessed their representation of thetarget. In Experiment 1 (N = 92) participantswere asked to list the most important objectsand relations in the passage. In Experiment 2(N = 80) participants were directly asked aboutthe target causal structures. In bothexperiments, responses of analogy subjects weremore likely to include given and inferredinformation that comprised the target causalmechanisms. Analogies in which a sourcepassage models causal mechanisms correspondingto those of a target passage appear to promotebetter representation of the details of targetcausal mechanisms, allowing a more fullydeveloped situation model of the target.     

White Privilege,Oppression, and Racial Identity Development: Implications for Supervision

Although the U.S. population is becoming increasingly diverse, the race of individuals entering the counseling profession remains predominantly White (S. P. Pack‐Brown, 1999). The authors define and explore the connection between White privilege and oppression and encourage the use of racial identity models to address these constructs with counselor trainees in supervision.