Realistic evaluation of hull performance for rowing shells, canoes, and kayaks in unsteady flow

In this study, we investigated the effect of hull dynamics in shallow water on the hydrodynamic performance of rowing shells as well as canoes and kayaks. An approach was developed to generate data in a towing tank using a test rig capable of reproducing realistic speed profiles. The impact of unsteady shallow-water effects on wave-making resistance was examined via experimental measurements on a benchmark hull. The data generated were used to explore the validity of a computational approach developed to predict unsteady shallow-water wave resistance. Comparison of measured and predicted results showed that the computational approach correctly predicted complex unsteady wave-resistance phenomena at low oscillation frequency and speed, but that total resistance was substantially under-predicted at moderate oscillation frequency and speed. It was postulated that this discrepancy arose from unsteady viscous effects. This was investigated via hot-film measurements for a full-scale single scull in unsteady flow in both towing-tank and field-trial conditions. Results suggested a strong link between acceleration and turbulence and demonstrated that the measured real-world viscous-flow behaviour could be successfully reproduced in the tank. Thus a suitable tank-test approach could provide a reliable guide to hull performance characterization in unsteady flow.     

(3) The Canadian Library Scene

Africa has not been a huge success story in the 20th-century library and information world. What, if anything, can the rest of the developing world learn from the African experience? In many countries library and information services are more highly developed than in any countries of Africa. But others share many of the handicaps of library and information services development which characterize African countries. For librarians and information workers from such countries, the African experience may be quite close to home and it may offer some useful lessons.

This paper attempts to outline the state of library development in Africa at the turn of the century in the context of the challenges and opportunities presented on the one hand by the world-wide developments in information technology, and on the other by the hoped for African Renaissance. Six promising responses to these challenges and opportunities are presented.

Africa is a large and diverse continent. In this paper it is not possible to give a historical perspective on library development in Africa. Given limitations of the author's experience, the emphasis is on Anglophone Africa and on the countries of the Southern African Development Community (SADC), and on public, university and national libraries.     

Film and Society

Bill Nichols IDEOLOGY AND THE IMAGE: SOCIAL REPRESENTATION IN THE CINEMA AND OTHER MEDIA (Bloomington: Indiana University Press, 1981 —$29.95/$9.95)

David Pirie ANATOMY OF THE MOVIES (New York: Macmillan, 1981—$15.95)

Nancy Lynn Schwartz THE HOLLYWOOD WRITER'S WARS (New York: Alfred A. Knopf, 1982—$17.95)

Gilbert Ad air VIETNAM ON FILM: FROM THE GREEN BERETS TO APOCALYPSE NOW (New York: Proteus, 1981— $13.95). Adair begins with John Wayne's The Green Berets (1968)

Edward D. C. Campbell, Jr. THE CELLULOID SOUTH (Knoxville: The University of Tennessee Press, 1981—$17.50)

Elizabeth Weatherford NATIVE AMERICANS ON FILM AND VIDEO (Available from Museum of the American Indian, Broadway at 155th Street, New York, NY 10032— $4.95, paper)     

An Issue of Trust: Are Commercial Databases Really Reliable?

Entrepreneurial researchers utilize databases on new and emerging businesses that provide the contact data and other demographic information for research samples. Based on a literature review, the integrity of this data is often assumed, and the vendor's claims as to its accuracy are relied upon. This article tests the accuracy and reliability of one such database, the U.S. New Business database from ReferenceUSA. Specifically, these businesses were contacted to test the validity of the information provided. The research findings suggest that the U.S. New Business database from ReferenceUSA is not a vetted database, and researchers cannot rely on the vendor's promise of accuracy.     

Grappling with teaching design and technology: a beginning teacher's experiences

This paper reports on an investigation into the first time implementation of a technology education unit of work by a beginning primary school teacher. The researchers monitored the teacher's implementation of the unit across a 6 week period using an interpretivist research approach. A variety of data sources were drawn upon including teacher and student interviews, video and audio recordings of small group and whole-class interactions, and student-developed artefacts. Providing appropriate learning activities to assist students to develop understanding about patterns and shapes incorporated into buildings and other structures to enhance strength and stability was a challenge faced by the beginning teacher. However, she drew support from a teaching resource, which provided guidance and structure for the teaching of technology concepts and processes related to strength and stability of structures and materials. The resource helped her to develop learning activities that were appropriate to the topic and to the needs of the students in her class. Implications of the study relate to the needs of teachers grappling with teaching design and technology for the first time and the support that they can gain from predetermined planning and teaching models and well-developed teaching resources.     

The technical adequacy of curriculum-based writing measures with English learners

The purpose of this study was to examine the validity and reliability of Curriculum-Based Measures in writing for English learners. Participants were 36 high school English learners with moderate to high levels of English language proficiency. Predictor variables were type of writing prompt (picture, narrative, and expository), time (3, 5, and 7 min), and scoring procedure (words written, words spelled correctly, correct word sequences, correct minus incorrect word sequences). Criterion variables were teacher ratings of writing performance and student performance on the Test of Written Language-III, the writing subtest of the Test of Emerging Academic English, and the Minnesota state writing test. Results supported the validity and reliability of a 5 to 7-min writing sample written in response to a narrative or picture prompt and scored for percent of correct word sequences, correct minus incorrect word sequences, or words written plus correct minus incorrect word sequences.     

Collaborating to enhance student reasoning: Frances' account of her reflections while teaching chemical equilibrium

Many researchers report that teachers' pedagogies often reflect non-constructivist referents, however less research reports on means of assisting teachers to become more constructivistly oriented. This paper reports on a teacher's changing perceptions during collaborative, two-year interpretive research involving two researchers, herself, and her students. The researchers collaborated with the teacher to promote students' theory-evidence coordination and use of word explanations, with an emphasis on developing and critiquing chemical equilibrium theory using experimental data. As the collaboration proceeded the teacher's beliefs and practice became increasingly focussed on students' reasoning and their discussion of ideas related to experimental data. The teacher reported benefits for herself and for her students as a consequence of this change. Key factors in relation to this change included researchers' modelling of target practices, and changes in the teacher's (a) perception of her students' abilities, (b) beliefs in relation to constructivism, and (c) understanding of chemistry concepts.     

Discursive Modes and Their Pedagogical Functions in Model-Based Inquiry (MBI) Classrooms

This research investigated the emergent discursive modes and their pedagogical functions found in model-based inquiry (MBI) science classrooms. A sample of four high school physics classrooms was video-recorded and analysed using a newly established discourse mode analysis framework. Qualitative methods were employed to identify the most salient types and sequences of discursive modes and to interpret their pedagogical functions in the context of MBI. Results indicated that exploring was one of the most frequently used discursive modes in the MBI classrooms. Sometimes two different types of exploring discourse were connected sequentially so that the pattern of exploring (scientific phenomena)–exploring (student ideas) appeared. The discursive sequences of exploring–retrieving and exploring–negotiating also emerged whereby the teacher guided students to align their models with the canonical knowledge of science. The teacher also helped students in modelling using elaborating and reformulating discourse modes as well as metadiscourse. Although the MBI classes were implemented in a manner similar to teacher-guided inquiry, it was also observed that students participated actively in several discursive practices. Implications for model- or modelling-based science instruction and science education research were discussed.     

Learning networks for schools: keeping up with the times or a leap into the unknown?

This article seeks to explore the ‘fit’ of ‘the network’ as an organizational form being implemented in schools in England. It considers current trends within education policy, pedagogy and educational technology in the context of these new service delivery models and relates these to the current interest in learning networks. The article draws upon the experience of school networks as it has been discussed in evaluation research and literature surveys, to highlight the issues around their implementation. The purpose, typology and potential tensions of educational networks are reviewed, with a particular focus on the Networked Learning Communities (NLCs) pioneered by the National College for School Leadership (NCSL). Although, on the face of things, the position of the ‘school network’ as a structural model seems logical, there are significant tensions which suggest that the implementation and development of meaningful and high quality networks is far more challenging than the government may appreciate.