Optimal pruning for tree-structured vector quantization

Tree-structured vector quantization (VQ) is a technique designed to represent a codebook that simplifies encoding as well as vector quantizer design. Most design algorithms for tree-structured VQ used in the past are based on heuristics that successively partition the input space. Recently, Chou, Lookabaugh and Gray proposed a tree-pruning heuristic in which a given initial tree is pruned backwards according to certain optimization criterion. We define the notion of an optimal pruned tree subject to a cost constraint and study the computational complexity of finding such an optimal tree for various cost functions. Under the assumption that all trees are equally probable, we show that, on the average, the number of pruned trees in a given tree is exponential in the number of leaves. Furthermore, we prove that finding an optimal pruned tree subject to constraints such as entropy or the expected-depth is NP-hard. However, we show that when the constraint is the number of leaves, the problem can be solved in polynomial time. We develop an algorithm to find the optimal pruned tree in O(nk) time, where n is the size of the initial tree and kis the constraint size.     

Using the web to encourage student-generated questions in large-format introductory biology classes

Students rarely ask questions related to course content in large-format introductory classes. The use of a Web-based forum devoted to student-generated questions was explored in a second-semester introductory biology course. Approximately 80% of the enrolled students asked at least one question about course content during each of three semesters during which this approach was implemented. About 95% of the students who posted questions reported reading the instructor's response to their questions. Although doing so did not contribute to their grade in the course, approximately 75% of the students reported reading questions posted by other students in the class. Approximately 60% of the students reported that the Web-based question-asking activity contributed to their learning of biology.     

Teachers' education, classroom quality, and young children's academic skills: results from seven studies of preschool programs

In an effort to provide high-quality preschool education, policymakers are increasingly requiring public preschool teachers to have at least a Bachelor's degree, preferably in early childhood education. Seven major studies of early care and education were used to predict classroom quality and children's academic outcomes from the educational attainment and major of teachers of 4-year-olds. The findings indicate largely null or contradictory associations, indicating that policies focused solely on increasing teachers' education will not suffice for improving classroom quality or maximizing children's academic gains. Instead, raising the effectiveness of early childhood education likely will require a broad range of professional development activities and supports targeted toward teachers' interactions with children.     

Attachment,Communication, and Relationship Functioning Among College Student Veterans and Nonveterans

This study examined attachment processes of college student veterans and nonveterans and further examined how veteran status and attachment style directly and indirectly predict relationship functioning. Results indicated that student veterans were more often dismissing in their attachment style but less often preoccupied than nonveteran students. Veteran status moderated the association between attachment style and dyadic consensus. The contributions of attachment and communication processes to overall relationship adjustment differed for student veterans and nonveterans.     

Development and Implementation of the Inaugural Anatomy Education Research Institute (AERI 2017)

Education research is increasingly being recognized as a legitimate route for faculty development in universities. However, many anatomy faculty lack the appropriate training and access to experienced mentors who can help them develop their own education research projects. Inspired by the American Physiological Society’s Institute for Teaching and Learning, the coauthors proposed and developed the inaugural Anatomy Education Research Institute (AERI 2017). Funded by an American Association of Anatomists Innovations grant, the five-day institute was held in Bloomington, Indiana in July 2017. The coauthors spent two years preparing the conference schedule, inviting speakers who could discuss education research topics and mentor applicants, reviewing applications, developing assessment instruments for the institute, and hosting the institute. A total of 62 registered participants (applicants and invited speakers) attended AERI 2017. Through a series of presentations and workshops, participants were introduced to many aspects of education research and the Scholarship of Teaching and Learning, including developing rigorous education research questions, determining appropriate methods to assess these questions, and searching the education research literature. Each day also included regular time devoted to work on their own education research project with help from more experienced mentors. Throughout the conference, participants were encouraged to post information on Twitter, using the hashtag #AERI2017. Participants had strong positive impressions of the conference and strongly requested future AERI conferences be held. Follow-up analyses will assess the institute in alignment with Kirkpatrick’s Four Levels of Evaluation Model, though preliminary evaluation indicates AERI 2017 met the original aims of the proposal.     

美国优质网络课程的案例介绍

近十年来,我国高校网络课程建设成果显著,但其中暴露出的理论与实践相脱离的现象也比较严重。通过介绍美国德克萨斯A&M大学Dooley教授开设的网络课程《远程教育的高级方法》,尝试剖析其作为优质网络课程在管理平台、教学设计、交互安排、评价方法以及支持服务等方面所具有的特征,以期与国内远程教育的研究者和实践者分享经验。