Stationary principles and potential functions for nonlinear networks

This paper presents a novel graph theoretic approach for deriving various stationary principles for single-element type nonlinear networks. The concepts of total content, co-content and hybrid content are generalized to that of total parametric content for resistive nonlinear networks containing multivalued elements. The results by Brayton and Moser on potential functions for complete m-ports are generalized to non-complete m-ports in terms of three pseudopotential functions; namely, the pseudo-content, pseudo- co-content and the pseudo-hybrid content. The precise criterion for which each of these pseudo-potential functions reduces to a legitimate potential function is shown to be the unique solvability of an implicit set of equations given explicitly in terms of standard topological matrices. Simple circuit theoretic sufficient conditions are given which require merely the positive-definiteness of the incremental resistance matrix of an auxiliary complete current-controlled p-port and the incremental conductance matrix of an auxiliary complete voltage-controlled q-port. These conditions also guarantee that a non-complete dynamic nonlinear network can be represented by a system of normal form differential equations in terms of a single mixed potential function.     

Training science teachers with fully-interactive,distance education technology

Conclusion Our experience with interactive distance education for science teachers has been both exciting and rewarding. This class has convinced us that activity-based science method classes can be presented with this technology. Working with distance education equipment requires the creative combination of long-established teaching techniques with novel procedures required by the technology. Although the technology does involve inevitable limitations and compromises, it sharpens some teaching skills and provides an opportunity for teachers to learn and do more science. As available tools for distance education become even more sophisticated, delivery techniques will have to be altered continually. Doubtlessly, technological developments will continue to be increasingly site friendly. In the future, one can anticipate forms of distance education that will enable communication with an infinite number of remote sites, thus establishing the definitive electronic science classroom.     

Using a Conceptual-Change Approach to Help Preservice Science Teachers Reorganize Their Knowledge Structures for Constructivist Teaching

This study, based on constructivist learning theory, examined how effectively preservice chemistry teachers (N = 43) can be educated to think flexibly and to reorganize their thinking in a way that may complement diverse ways students approach the subject domain. The teacher's cognitive structure was assessed prior to and after a conceptual change intervention using flow-map narrative analyses. There was a significant change in the organization of the preservice teacher's narrative after the conceptual change intervention, including greater networking of ideas and more thematic development of the content. Hence, a conceptual change approach may be a useful way to educate teachers to be more responsive to student individual differences when planning and delivering science lessons.     

Transfer of Learning From An Action Reflection Learning™ Program*

Learning transfer from training and development programs to the workplace is a central issue of concern for human resource development specialists. Action Reflection Learning™ (ARL™) is a form of action learning that places emphasis on the development of targeted competencies while teams of participants work on real problems which have been given to them by a sponsor. This article examines the kinds of learning and learning transfer that took place in an international food company that was striving to become a global organization. Data were collected through both field observation and formal interviews and analyzed by a team of researchers. Conclusions about the degree of transfer and the mechanisms and process supporting it are presented.     

In pursuit of African scholarship: unpacking engagement

Engagement between higher education and other societal sectors is a key theme in higher education discourse in South Africa, as it is in other countries. In South Africa, however, engagement has gained additional status as an appropriate strategy for pursuing African Scholarship. On the ground, however, inequitable power relationships and erratic participation have posed serious challenges to the effectiveness and sustainability of engagement initiatives. From the experiences of seven South African academics and the local community members and service-providers with whom they engaged in service-learning, three factors emerged as mediating the power/participation dynamic of their engagement. The impact of these factors, namely, structure, meaning, and place and time, are discussed, leading to the conclusions that scholarly engagement requires ideological and practical support from higher education institutions and further study in South African contexts.

Cognitive Set and Coping Strategy Affect Mothers' Sensitivity to Infant Cries: A Signal Detection Approach

We used Signal Detection methodology to examine how cognitiveset affects mothers' response to an infant cry. We asked whether a cry from a "difficult" versus an "easy" infant would elicit a change in sensitivity or response bias in mother processing of these cries. Thirty-eight mothers of 4- to 6-month-old infants participated in a Signal Detection task in which they were asked whether they could detect differences between a standard cry and 1 to 4 cry variants. Cry variants differed from the standard cry in small, systematic changes in fundamental frequency. The task was conducted in 2 parts; each part constituted a condition wherein mother received a cognitive set manipulation that labeled the identical cry as coming from either a'difficult'or an "easy" infant. An increase in mothers' sensitivity was associated with the "difficult" infant cognitive set. We examined as well how a coping strategy(illusion of control) affected cry signal processing. Mothers who Exhibited high illusory control were least -sensitive in detecting differences between cries. Two information-prcessing, measures response time and heart rate, were also collected and showed that greater sensitivity was associated with more efficient processing of the cry signal.     

Reader,Word, and Character Attributes Contributing to Chinese Children’s Concept of Word

Concept of word—the awareness of how words differ from nonwords or other linguistic properties—is important to learning to read Chinese because words in Chinese texts are not separated by space, and most characters can be productively compounded with other characters to form new words. The current study examined the effects of reader, word, and character attributes on Chinese children’s concept of word in text. A total of 164 fifth-grade Chinese children participated in this study. Concept of word was measured by children’s lexical decisions about words and nonwords embedded in strings of characters. Cross-classified multilevel logistic models showed that reader attributes, including reading comprehension, vocabulary knowledge, and morphological awareness, interacted with certain word or character attributes in predicting children’s lexical decisions about words or nonwords. This study sheds light on the complex relationships between reader, word, and character attributes in the formation of concept of word in Chinese.     

Information and Reliability for Percentile Ranks and Other Monotonic Transformations of the Number-Correct Score: Reply to De Gruijter

De Gruijter (1997) has claimed that May and Nicewander (1994) erred on two points that indicated that both reliability and information in the number-correct score could be reduced considerably by converting to percentile ranks. The points raised by De Gruijter are very well taken, and we are pleased to have an opportunity to respond.