Improving document clustering in a learned concept space

Most document clustering algorithms operate in a high dimensional bag-of-words space. The inherent presence of noise in such representation obviously degrades the performance of most of these approaches. In this paper we investigate an unsupervised dimensionality reduction technique for document clustering. This technique is based upon the assumption that terms co-occurring in the same context with the same frequencies are semantically related. On the basis of this assumption we first find term clusters using a classification version of the EM algorithm. Documents are then represented in the space of these term clusters and a multinomial mixture model (MM) is used to build document clusters. We empirically show on four document collections, Reuters-21578, Reuters RCV2-French, 20Newsgroups and WebKB, that this new text representation noticeably increases the performance of the MM model. By relating the proposed approach to the Probabilistic Latent Semantic Analysis (PLSA) model we further propose an extension of the latter in which an extra latent variable allows the model to co-cluster documents and terms simultaneously. We show on these four datasets that the proposed extended version of the PLSA model produces statistically significant improvements with respect to two clustering measures over all variants of the original PLSA and the MM models.     

Mother–Child Attachment From Infancy to the Preschool Years: Predicting Security and Stability

Relations between maternal mind‐mindedness (appropriate and nonattuned mind‐related comments), children's age‐2 perspective‐taking abilities, and attachment security at 44 (n = 165) and 51 (n = 128) months were investigated. Nonattuned comments predicted insecure preschool attachment, via insecure 15‐month attachment security (44‐month attachment) and poorer age‐2 perspective‐taking abilities (51‐month attachment). With regard to attachment stability, higher perspective‐taking abilities distinguished the stable secure groups from (a) the stable insecure groups and (b) children who changed from secure to insecure (at trend level). These effects were independent of child gender, stressful life events, and socioeconomic status (SES). The contribution of these findings to our understanding of stability and change in attachment security from infancy to the preschool years is discussed.     

Pensar con libertad de elección y en colaboración: introducción de la escritura en proceso en una escuela estonia

Frente al modelo predominante en buena parte de la didáctica occidental de la escritura, basado en tareas y habilidades aisladas y en la realización individualizada, se expone aquí una experiencia de didáctica de “la escritura en proceso” que invierte los términos hacia el proceso global y la realización en colaboración.     

Relating to the ‘Other’: transformative,intercultural learning in post-colonial contexts

In this paper we use Transformative Learning Theory as a lens for making sense of teachers’ learning from study visits to the Global South. Transformative Learning theory is made up of two main elements: the form of transformations and the processes that support transformations. ‘Life changing’ experiences as expressed by study visit participants have been interpreted as transformational, but questions about who and what are transformed, and whether this is at the expense of the ‘Other’, are rarely addressed. Drawing on data from a project investigating study visits for UK teachers to Gambia and Southern India, we analyse the form that changes take and discuss whether these can be seen as transformational. We argue that without an explicit focus on relational forms of knowledge about culture and identity, self and other, the potential for transformations in how we relate to, and learn from, each other in postcolonial contexts is severely diminished.     

From students to teachers: using surveys to build a culture of evidence and inquiry

In an effort to make decisions about teacher education policy and practice that were informed by research and evidence, participants in Boston College's ‘Teachers for a New Era’ Evidence Team (http://www.teachersforanewera.org) designed a portfolio of assessments and studies. This article describes one project in the portfolio – a series of surveys that trace teacher candidates' experiences over time and track shifts in these experiences as respondents progress from students during the pre‐service period to teachers in the first few years of work in the profession. The article illustrates how various constituencies in the teacher education programme and the larger university used survey data to guide practice, shape policies, and raise new questions about the curriculum, relationships with schools, and the performance of teachers and their pupils. The article argues that these surveys helped to create a new ‘culture of evidence and inquiry’ within which decisions about local policy and practice were made in the teacher preparation programme and the larger university.     

Structural pattern differences in course enrollment rates among community college students

This study tested a structural equation model of enrollment patterns of white and Hispanic males and females in two-year institutions and the invariance of parameter estimates among the different subgroups in the study. The model represented a multiequation model with three latent endogenous variables, high school academic preparation in mathematics and science, mathematics and science attitudes, and the dependent variable, enrollment patterns in mathematics and science courses. Exogenous variables included parents' education, levels of encouragement by others, and high school grades. Structural equation modeling was used to examine the structural and measurement coefficients of the hypothesized causal model for all subgroups in the study. In summary, an examination of the direct and total effect coefficients revealed different underlying patterns of factors for white and Hispanic females. No convergence on the model was found for white and Hispanic males. Equality constraints on all structural coefficients for both white and Hispanic females were tested and results indicated that all parameter estimates in the structural models for both subgroups were significantly different from each other.