Clustering student skill set profiles in a unit hypercube using mixtures of multivariate betas

<br>This paper presents a finite mixture of multivariate betas as a new model-based clustering method tailored to applications where the feature space is constrained to the unit hypercube. The mixture component densities are taken to be conditionally independent, univariate unimodal beta densities (from the subclass of reparameterized beta densities given by Bagnato and Punzo 2013). The EM algorithm used to fit this mixture is discussed in detail, and results from both this beta mixture model and the more standard Gaussian model-based clustering are presented for simulated skill mastery data from a common cognitive diagnosis model and for real data from the Assistment System online mathematics tutor (Feng et al 2009). The multivariate beta mixture appears to outperform the standard Gaussian model-based clustering approach, as would be expected on the constrained space. Fewer components are selected (by BIC-ICL) in the beta mixture than in the Gaussian mixture, and the resulting clusters seem more reasonable and interpretable.</br> <br>This article is in technical report form, the final publication is available at http://www.springerlink.com/openurl.asp?genre=article &id=doi:10.1007/s11634-013-0149-z</br&gt

Issue-based teaching in economics

Economics has evolved into a highly technical academic discipline. Considerable weight is placed on the ability of academic economists to be familiar and skilled in the use of mathematical and statistical techniques. This is how academic economists tend to be judged by their peers. As a consequence, academic economists in demonstrating their ability to use such techniques often apply their work to abstract problems or confine themselves to conceptual discussions. But, when adopted by economic instructors there is a real danger that students become disengaged and de-motivated which is of particular significance at a time of increasing concerns about recruitment and retention rates. This paper addresses how the adoption of issue-based teaching to level 1 economics undergraduates would help in motivating students to engage with economics. It argues that issue-based teaching can enable students to achieve higher levels of learning with students recognising that they can apply economic concepts and tools across a series of real and relevant issues. Although the paper is directed towards the teaching of economics it is, nonetheless, of relevance to all instructors of level 1 students.Issues-based teaching, engagement, motivation, learning theory.

Got Caries? Breast milk and Early Childhood Caries?

Objective: To provide an analysis of the association between the longevity of breastfeeding and development of ECC. Determine the optimal time frame in which mothers should cease breastfeeding to reduce ECC development. Methods: Dr. Brickhouse, PubMed, Google Scholar and other scholarly databases were utilized to find current scientific evidence on the effects of breast milk on ECC. Relevant articles were summarized to write a review of literature. 16 articles published from 2015 to the present date were reviewed and cited. Results: From the studies, there is strong evidence to support breastfeeding beyond 12 months of age increases the prevalence of ECC. Furthermore, increased frequency and duration of breastfeeding leads to higher incidence of ECC. Conclusion: Findings indicate dental health care providers should recommend either ceasing breastfeeding at 12 months of age or provide ECC prevention education to caregivers. Further research is required to minimize data discrepancies between US and international countries.https://scholarscompass.vcu.edu/denh_student/1002/thumbnail.jp

Erosion of Access to Abortion in the United States: Lessons for Australia

Since the legalisation of abortion in the United States (US) in 1973, access to abortion has been restricted and under attack from multiple fronts. From a pro-choice perspective, this article analyses the way women’s access to abortion has been eroded in the US. This article considers: Roe v Wade and chronicles the subsequent cases decided by the US Supreme Court which have gradually dismantled its holding; the various US state and federal legislative restrictions on abortion and their impact on access to abortion; the new composition of the US Supreme Court and the consequences for women’s access to legal abortion; and a brief overview of abortion in Australia. Awareness of anti-choice tactics used to restrict access to abortion in the US may prevent a similar erosion of abortion rights in Australia

Incorporating Field Excavations in Introduction to Archaeology

Most archaeology students first experience field work during a field school aimed at upper-division undergraduate majors. An excavation component in an Introduction to Archaeology class, however, can create an unequaled educational experience for students at all levels of experience and interest in archaeology. Excavations help students to master basic field methods, understand the nature of archaeological inference, recognize the strengths and limitations of archaeological data, grapple with archaeological ethics, and foster a sense of archaeological stewardship. This paper explores the outcomes of providing a field experience in the introductory class at the University of Minnesota Morris, the liberal arts campus of the University of Minnesota system. The community-instigated excavation led to increased student learning that was particularly focused on higher-level cognitive activities, such as reflection and application. Although the logistics of field work can be prohibitively difficult, faculty may underestimate both the advantages and ease of providing this hands-on experience to their students

Detecting LINC Complex Mps3 and Nuclear Pore Complex Ndj1 Protein Interactions on Yeast Nuclear Membrane s through Fluorescence Microscopy

Though cancer cells have been shown to have abnormal nuclear morphologies and responses to mechanical forces, the mechanisms of how mechanical stress is translated into cellular action and structural reorganization within the nuclear envelope are largely unexplored. The Linker of Nucleoskeleton and Cytoskeleton (LINC) complex is a transmembrane protein complex that connects the actin cytoskeleton to the lamin nucleoskeleton, enabling mechanical forces to be translated between the cytoplasm and the nucleus. In cells exposed to physical stress, nuclear pore complexes (NPCs) –which control the exchange of biochemical signals and macromolecules in and out of the nucleus through mRNA export –have been shown to colocalize with LINC complexes. A better comprehension of the translation of physical forces into changes in gene expressioncan be gained through analysis ofthe existence of interactions between specificNPC and LINC proteins. Using the model organism Saccharomyces cerevisiae, thepresence of an interaction between NPC inner nuclear envelope proteins and Ndj1 in the LINC complex was tested using a split-green fluorescent proteinmicroscopy approach. To do this, Itransformed complementarysequences for Venussplit fluorescent protein for integration into the yeast cell genome, thus tagging NPC and LINC proteins. After the split-GFP sequenceswere integrated into yeast DNA, fluorescent microscopy was performed to determine the level and locations of protein-protein interactions. Gelelectrophoresis results showed thatthe NPC proteinNdj1was successfully tagged with VC (Venus C-terminus)into cells that that were Mps3-VN (a LINC protein) tagged. In the fluorescent microscopy of yeast tagged with Ndj1-VC, many cells fluoresced, but there was no clear localization around the nuclear envelope. However, there were issues with the fluorescent microscopy for the positive control of yeast already producing Venus split-GFP, so no conclusive results can be made about the Ndj1 fluorescence images until the control is properly completed. Future directions for this study include improving the positive control, and creating environments with mechanical and chemical stimuli to trigger the colocalization of NPC’s and LINC complexes through which interactions are more likely to be detected in the fluorescence microcopy

sARI: a soft agreement measure for class partitions incorporating assignment probabilities

Agreement indices are commonly used to summarize the performance of both classification and clustering methods. The easy interpretation/intuition and desirable properties that result from the Rand and adjusted Rand indices, has led to their popularity over other available indices. While more algorithmic clustering approaches like k-means and hierarchical clustering produce hard partition assignments (assigning observations to a single cluster), other techniques like model-based clustering include information about the certainty of allocation of objects through class membership probabilities (soft partitions). To assess performance using traditional indices, e.g., the adjusted Rand index (ARI), the soft partition is mapped to a hard set of assignments, which commonly overstates the certainty of correct assignments. This paper proposes an extension of the ARI, the soft adjusted Rand index (sARI), with similar intuition and interpretation but also incorporating information from one or two soft partitions. It can be used in conjunction with the ARI, comparing the similarities of hard to soft, or soft to soft partitions to the similarities of the mapped hard partitions. Simulation study results support the intuition that in general, mapping to hard partitions tends to increase the measure of similarity between partitions. In applications, the sARI more accurately reflects the cluster boundary overlap commonly seen in real data

Fire Station Siting Study

The City of Hammond Fire Department, in need of a new station location, worked with Shive-Hattery of South Bend to study the optimal location for fire stations in Hammond. This presentation guides the audience through the data collection, processing the data into GIS, and comparing population density to find a site best suited to the needs of Hammond Residents