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Link to this article: http://journals.cambridge.org/abstract_S095834401400041XHow to cite this article: Huifen Lin Computer-mediated communication (CMC) in L2 oral prociency development: A metaanalysis. ReCALL, AbstractThe ever growing interest in the development of foreign or second (L2) oral proficiency in a computer-mediated communication (CMC) classroom has resulted in a large body of studies looking at both the direct and indirect effects of CMC interventions on the acquisition of oral competences. The present study employed a quantitative meta-analytic approach to investigate such effects by synthesizing (quasi)experimental studies that provide empirical quantitative data for effect size calculation. A literature search located 25 relevant studies for the final analysis. Each study was independently coded for learner, design and publication characteristics. The averaged effect size was estimated from the included studies. The results of the meta-analysis reveal that communication mediated by computer/technologies produced a moderate positive effect on L2 learners' oral proficiency compared to face-to-face (F2F) communication or no interaction. Furthermore, CMC has roughly similar effect on pronunciation, lexical and syntactic level of oral production; however, it might have a negative impact on fluency and accuracy. This meta-analysis also found that the effect of CMC on oral proficiency depends on several methodological factors such as task type, outcome measurement, treatment length, and assessment task. Major findings of the current meta-analysis include: (1) studies relying on elicited data are superior to those utilizing naturalistic data; (2) reading aloud seems to be the task that could elicit the best oral performance from students;(3) surprisingly, CMC appeared to be harmful for accuracy and fluency; (4) studies that employed decision-making generated the largest effect size, followed by studies that used more than one task type; (5) among the four tasks, jigsaw actually generated a negative effect on oral performance; and (6) as the most popular task employed by primary researchers, opinion-exchange studies produced the smallest effect size. These findings need to be interpreted as exploratory rather than confirmatory since each of them became less trustworthy after taking into consideration numerous other factors such as CMC task and the particular CMC tool used, etc. Future research suggestions are provided and the limitations of this meta-analysis are addressed.

Allophycocyanin (APC) is one of the phycobiliproteins expressed in cyanobacteria. Phycobiliproteins contain a covalently bound chromophore, and thus, they are valuable as fluorescent probes. Biosynthesis of a functional phycobiliprotein is achieved by a bilin attachment process between the chromophore and apoprotein. Chromophore lyases are necessary to catalyze the chromophorylation of cyanobacterial phycobiliproteins, such as C-phycocyanin, and phycoerythrocyanin. To identify the lyase that catalyzes the chromophorylation of the APC alpha-subunit (ApcA), we searched the entire genomes of two cyanobacteria, Synechocystis sp. PCC6803 and Anabaena sp. PCC 7120; however, these genomes do not appear to encode an APC-specific chromophore lyase. In this study, chromophorylated ApcA (chromo-ApcA) was obtained via a spontaneous bilin attachment reaction. The absorption and fluorescence characteristics of chromo-ApcA were similar to those of the native APC alpha-subunit. The extent of chromophore attachment to apo-ApcA was comparable to that of the lyase-catalyzed reactions for other phycobiliproteins. These results indicate that ApcA has autocatalytic bilin:biliprotein lyase activity.

This study investigated the effectiveness of three different levels of enhancement strategies utilized to facilitate students' learning from static and animated visualization when taking the time-on-task into consideration. Participants were randomly assigned to six treatment groups, and then took four criterion measures. The time-on-task was measured and used as a covariate in the analysis. The results suggest that animation is more effective than static visuals for improving learning across all levels of learning. Questions plus feedback embedded into the visualized material are most effective in enhancing higher-level but not lower-level learning objectives. Furthermore, time-on-task may be interpreted differently. On the one hand, students should be allowed as much time as needed to learn material when it is enriched, such as in the animated lesson. On the other hand, requiring students in a static-only treatment to review the visuals may produce the same learning effect as the use of animated visuals.

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