PenQuest Volume 3, Number 2

Table of Contents for this Volume: Untitled by Joe Avanzini Woodcutting on Lost Mountain by Tess Gallagher Untitled by Judith Mizrahi Women I have loved by Dottie Fletcher Untitled by Rick Wagner Untold Stories by William Slaughter Untitled by Steve Balunan Two German Women by Dottie Fletcher Untitled by Anne Calloway Tourists by Carol Grimes Untitled by Win Lyons Rollin\u27 Bones by Barbara Ritchey Untitled by Steve Balunan Hannukah Harbor by Jerry Nelson Night-letter by William Slaughter Untitled by Bruce Abbey Domestic by Carol Grimes Untitled by Steve Balunan The Storm Pit by Howard Denson Untitled by Judith Mizrahi Hattie by Dottie Fletcher Untitled by Linda Willcox Untitled by Helen Hagador

Coding by Choice: A Transitional Analysis of Social Participation Patterns and Programming Contributions in the Online Scratch Community

While massive online communities have drawn the attention of researchers and educators on their potential to support active collaborative work, knowledge sharing, and user-generated content, few studies examine participation in these communities at scale. The little research that does exist attends almost solely to adults rather than communities to support youths’ learning and identity development. In this chapter, we tackle two challenges related to understanding social practices that support learning in massive social networking forums where users engage in design. We examined a youth programmer community, called Scratch.mit.edu, that garners the voluntary participation of millions of young people worldwide. We report on site-wide distributions and patterns of participation that illuminate the relevance of different online social practices to ongoing involvement in the online community. Drawing on a random sample of more than 5000 active users of Scratch.mit.edu over a 3-month time period in early 2012, we examine log files that captured the frequency of three types of social practices that contribute to enduring participation: DIY participatory activities, socially supportive actions, and socially engaging interactions. Using latent transition analysis, we found (1) distinct patterns of participation (classes) across three time points (e.g., high networkers who are generally active, commenters who focus mainly on social participation, downloaders engaging in DIY participatory activities), (2) unique migration changes in class membership across time, (3) relatively equal gender representation across these classes, and (4) importance of membership length (or age) in terms of class memberships. In the discussion, we review our approach to analysis and outline implications for the design and study of online communities and tools for youth

Structural effect of aliovalent Doping in lead perovskites

Composition–structure relationships are needed for various applications, including lattice-matching for heteroepitaxy; however, a general model to predict lattice constants in defective perovskites is not yet available because the exact nature of A-site vacancies in perovskites remains largely unknown. In this study, it has been shown experimentally via Le Bail refinements of x-ray diffraction data that such vacancies in (Pb1−3xLa2x□x)TiO3 and (Pb1−3xLa2x□x)(Zr0.6Ti0.4)O3 have an effective size due to both Coulombic repulsion of coordinating oxygen ions and bond relaxation. For the first time, cell volume can be predicted in this system from stoichiometry and published ionic radii data alone to within 0.2% accuracy within View the MathML source0≤x≤13 compositional range and <0.3% accuracy all the way to View the MathML sourcex=13. The model may be applied to other perovskite systems and eventually provide tailored properties (magnetic, dielectric, and other) based on improved structure predictions