Development of Two-Dimensional Classroom Discourse Analysis Tool (CDAT): scientific reasoning and dialog patterns in the secondary science classes.

BACKGROUND: In a science classroom, students do not simply learn scientific ways of doing, knowing, and reasoning unless they find ways of appropriating scientific discourse. In the Next Generation Science Standards, major forms of scientific discourse are emphasized as a main part of the Science and Engineering Practices. To enhance student engagement in scientific discourse, teachers need to help students differentiate scientific ways of talking from everyday ways of talking. Thus, science teachers should be able to be aware of the differences to provide opportunities for students to engage in scientific discourse. RESULTS: In this study, the classroom discourse analysis tool (CDAT) was developed to help science teachers and educators identify the patterns of their classroom discourse with the lens of scientific reasoning. The CDAT suggests a new way of discourse pattern finding with the two-dimensional graphic organizer and the quantitative data produced by the coding. To pilot the CDAT analysis, 13 videos and transcripts of two middle and one high school teachers' physical science classes were viewed and analyzed. The results from CDAT coding show illustrative information that characterizes the classroom discourse patterns in relation to scientific reasoning and teachers' questioning and feedback. A coded CDAT table shows what reasoning components used in the classroom dialogs between the teacher and students. It also shows how students engaged in the dialogs with the variations of their answers by the teacher's question and feedback. CONCLUSION: The results show the patterns of students' responses strongly depend on teacher's question or feedback. In addition, this analysis also generates various quantitative data that represent certain characteristics of the classroom discourse, i.e., length of dialog and the number of reasoning components used. The possible implications of CDAT analysis are to explore the relationships between teachers' discourse patterns and students' achievement along with changes in their reasoning skills. Student attitudinal outcomes such as motivations, interests, or self-efficacy could also be compared by the classroom discourse patterns revealed by CDAT. CDAT analysis itself can also be used in a teacher professional development as an intervention to help teachers see their classroom discourse patterns.

New evidence for geographic variation in the role of human papillomavirus in tonsillar carcinogenesis.

AIMS: Our previous studies of tonsillar cancers from New South Wales, Australia, and Jilin Province in the north-east of China, provided evidence that the proportion of these cancers attributable to human papillomavirus (HPV) varies geographically. This study provides the first data on HPV in tonsillar cancers from Hong Kong. METHODS: A total of 49 Hong Kong tonsillar cancers were analysed for HPV DNA by PCR/sequencing and for p16(INK4A), retinoblastoma (pRb) protein, cyclin D1 and p53 expression by semiquantitative immunohistochemistry as evidence of virus causality. Results were compared with those from New South Wales and Jilin Province. RESULTS: Of the 31 Hong Kong cancers with amplifiable DNA, nine (29%) were HPV positive by PCR compared with 46% from New South Wales and 0% from Jilin Province. HPV positivity correlated with female gender, young age, over-expression of p16(INK4A) and loss of pRb and cyclin D1. Five-year disease-specific survival for patients with HPV positive and HPV negative cancers was 82 and 42%, respectively. Relationships between HPV status and cell protein expression in Hong Kong cancers were consistent with those from New South Wales and Jilin Province. The proportion of HPV-associated cancers reflected the relative incidence of oropharyngeal cancer in these regions. CONCLUSIONS: HPV is responsible for a small proportion of tonsillar cancers in Hong Kong patients. Differences in the proportions of tumours attributable to HPV in Hong Kong, New South Wales and Jilin Province may be due to environmental, cultural or genetic factors in the different populations.

Cytoplasmic expression of nm23 predicts the potential for cerebral metastasis in patients with primary cutaneous melanoma.

The nm23 gene is a putative tumour and metastasis suppressor gene. A number of studies have found that reduction of its expression is associated with increased metastatic potential in several human malignancies. Similarly, clinical studies have shown correlation between reduced nm23 protein expression and a poor prognosis. The aim of this study was to determine if a relationship exists between nm23 expression in primary cutaneous melanomas with or without cerebral metastases. Paraffin-embedded tissues were retrieved from 21 patients with primary cutaneous melanomas (n=21) and who subsequently developed cerebral metastases (n=24). Primary cutaneous melanomas with no regional or organ metastases within a 10 year period were used as control cases (n=34). Nm23 staining was localized in the cytoplasm of the tumour cells. Most of the control cases showed strong expression, whereas the majority of the primary melanomas with cerebral metastases showed no or weak expression of nm23. The cerebral metastases mostly showed strong expression. In summary, the results of this study may have significant prognostic implications for patients presenting with cutaneous melanoma. Patients with cutaneous melanomas with a low expression of nm23 appear to be more at risk of developing brain metastases.