Interactive Relationships Among Teachers' Intentions, Beliefs, Pedagogical Content Knowledge and Classroom Instruction on the Nature of Science

The purpose of this study was to investigate the relationship among teachers’ intentions, beliefs, pedagogical content knowledge (PCK) and their classroom practice, and to delineate factors that cause changes in teachers’ intentions, beliefs and PCK. Four in-service secondary science teachers comprised the sample for this study. Throughout the academic year, data sources including classroom observations, pre- and post-lesson discussions, instructional materials, students’ works and questionnaires that measured teachers’ understanding of NOS were collected. Preliminary result of Tammy, a beginning teacher, indicated that there were interactive relationships among her intention, beliefs, PCK and classroom practice. Having started to teach NOS, Tammy gained better understanding of NOS, reinforced her view that teaching NOS is important and built confi dence in her own ability to teach NOS while developing her PCK. Tammy’s experience of teaching NOS demonstrated a positive feedback effect of classroom practice on cultivating teachers’ intentions and beliefs. The result of another teacher, Kevin, demonstrated the strong infl uence of teachers’ existing beliefs on the translation of teachers’ understanding of NOS into classroom practice, and revealed a need for change in examinations that is coherent with the educational objective of helping students develop an adequate understanding of NOS

Review of the inverse Knapp procedure: indications, effectiveness and results

Purpose To evaluate the indications and results of inverse Knapp procedures performed at one institution over a 10 year period between 1987 and 1996

Correction of strain errors induced by small rigid-body motions in electronic speckle pattern interferometry measurement

Electronic speckle pattern interferometry (ESPI) can provide non-contact, high-precision, and full-field displacement measurement. This technique is particularly useful for determining deformations on objects with high strain gradients and complex shapes. However, small rigid-body movements of the object being measured can spoil the accuracy of the ESPI measurement and cause dramatic strain errors. Based on the theory of geometric optics, formulae for evaluating the theoretical strain errors caused by different modes of rigid-body motion were explicitly derived. The proposed formulae were validated by comparing the theoretical strain errors generated from a set of known rigid-body motions with the strains obtained by ESPI. The experimental results agreed well with the theoretical results. The results further revealed that the out-of-plane rigid-body motion had the strongest influence on the strain errors among the rigid-body movements considered. An out-of-plane movement of 0.01 mm could generate a strain error of approximately 40 μ ϵ. Finally, a correction procedure to eliminate the strain errors has been proposed. The effectiveness of the procedure was demonstrated with a four-point bending test on a concrete beam. This study on the quantitative evaluation and correction of strain errors due to various rigid-body movements is very useful for the practical applications of the ESPI technique in deformation measurement

Cell transplantation as a treatment for retinal disease

It has been shown that photoreceptor degeneration can be limited in experimental animals by transplantation of fresh RPE to the subretinal space. There is also evidence that retinal cell transplants can be used to reconstruct retinal circuitry in dystrophic animals. Here we describe and review recent developments that highlight the necessary steps that should be taken prior to embarking on clinical trials in humans. (C) 2001 Elsevier Science Ltd. All rights reserved