Electroosmotic flow in vapor deposited silicon dioxide and nitride microchannels

Electroosmotic flow was studied in thin film microchannels with silicon dioxide and silicon nitride sidewalls formed using plasma-enhanced chemical vapor deposition (PECVD). A sacrificial etching process was employed for channel fabrication allowing for cross-sections with heights of 3 μm, ranging from 2 μm to 50 μm in width. Flow rates were measured for single channels and multichannel electroosmotic pump structures for pH levels ranging from 2.6 to 8.3, and zeta potentials were calculated for both silicon dioxide and silicon nitride surfaces. Flow rates as high as 0.086 μL∕min were measured for nitride multichannel pumps at applied electric fields of 300 V∕mm. The surface characteristics of PECVD nitride were analyzed and compared to more well-known oxide surfaces to determine the density of amine sites compared to silanol sites.     

Cognitive validity of students’ self-reports of classroom mastery goal structure: What students are thinking and why it matters

Cognitive interviews were employed to systematically examine the cognitive validity of self-report survey items extensively used to assess classroom mastery goal structure. In a sample of elementary and middle school students, items were identified that functioned according to their intended meaning and those eliciting less accurate interpretations as conceptually defined by mastery goal structure cognitive validity criteria. Evidence suggested that items framed to focus on students’ teachers (i.e., teacher goals) were more cognitively valid than were items that focused students on their classroom context. Items with abstract terms yielded less accurate interpretations. We discuss implications of determining the cognitive validity of scales used to assess achievement goal structure and related self-report instruments.     

How ‘free distribution’ impacts your business model: is it really free?

The widespread perceptions associated with digital technology and the internet are forcing publishers to look to ways to shift the balance of the burden of cost away from the user. We describe seven examples of ‘free’ distribution and discuss how they impact publishing business models.     

Student perceptions of the classroom environment: Relations to motivation and achievement in mathematics

This study examined the relationship of 979 middle school students’ perceptions of their mathematics classroom environment to their motivation and achievement. Structural equation modeling indicated that motivational variables (utility, personal achievement goals, efficacy) mediated the influence of perceived teacher expectations, teacher support and use of reform practices on mathematics standardised test scores. Our study provides empirical evidence that students’ perceptions that their teachers believe that they are capable of learning and understanding mathematics positively relate to their Mastery and Performance Goal orientations and mathematics Utility. Further, we found an interaction between students’ perceptions of the frequency of reform practice use in their mathematics classroom and mathematics efficacy. For students with lower mathematics efficacy, their perceptions of more frequent use of reform practices in their mathematics class related to higher standardised test performance. For students with higher mathematics efficacy, perceived use of reform practices did not significantly relate to standardised test performance. These data suggest that frequent exposure to reform practices is especially critical for students who judge themselves as being less capable in mathematics and who are lower performers. This finding differs from prior research that has suggested that reform practice use benefits higher achievers but not lower achievers. An important implication of our study is the need for coordinated, ongoing professional development that highlights reform pedagogy and beliefs while also focusing on student motivation theories and strategies.     

Effects of context on judgments concerning the reality status of novel entities

Three studies examined the effects of context on decisions about the reality status of novel entities. In Experiment 1 (144, 3- to 5-year-olds), participants less often claimed that novel entities were real when they were introduced in a fantastical than in a scientific context. Experiment 2 (61, 4- to 5-year-olds) revealed that defining novel entities with reference to scientific entities had a stronger effect on reality status judgments than did hearing scientifically oriented stories before encountering the novel entities. The results from Experiment 3 (192, 3- to 6-year-olds) indicated that definitions that support inferences facilitate reality status judgments more than do definitions that simply associate novel and familiar entities. These findings demonstrate that children share with adults an important means of assessing reality status.