Seizing the Moment: Realizing the Promise of Student-Centered Learning

This brief outlines policy recommendations for supporting student-centered learning at the local, state, and federal level

Estimating and modeling the dynamics of the intensity of infection with Schistosoma japonicum in villagers of Leyte, Philippines. Part II: Intensity-specific transmission of S. japonicum. The schistosomiasis transmission and ecology project

A dynamic model of Schistosoma japonicum transmission is presented that incorporates effects of infection intensity, age, and sex. We use four infection intensity classes to investigate the impact of ecologic changes and public health interventions on the burden of infection within communities. Age- and sex-specific infection data from three disease-endemic villages in the Philippines are used to estimate the parameters of the model. The model gives good qualitative agreement with observed fecal egg counts adjusted for the accuracy of the Kato-Katz examination. Our results suggest that differences in infection burden between villages are caused by differences in both the infection process and the recovery process in humans. We describe the potential impact of mass treatment of all humans on the numbers with high infection. Furthermore, we show that a sudden reduction in snail population size would affect high prevalence and low prevalence communities in different ways. Copyright © 2005 by The American Society of Tropical Medicine and Hygiene.published_or_final_versio

Patient-Reported Outcomes of Primary Total Ankle Arthroplasty in Patients Aged \u3c50 Years

Background: Compared to more prevalent arthritic conditions, ankle arthritis is complicated by an earlier age of onset. Recently published data demonstrates excellent survivorship and complication rates in short-/midterm follow-up of younger patients who received a primary total ankle arthroplasty (TAA). Additionally, older TAA patients display comparable reported outcomes relative to hip/knee arthroplasty. However, there remains a paucity of literature surrounding the reported outcomes of younger patients undergoing TAA. Thus, our aim was to assess the reported outcomes of individuals aged \u3c50 years receiving a primary TAA. Methods: A retrospective cohort analysis of adult patients \u3c50 years who received a primary total ankle replacement was conducted. Patient demographics, diagnosis, treatment, and outcome characteristics were recorded from a chart review of 41 patients with at least 1 year of postoperative clinical follow-up. Postoperative reported outcomes were obtained via telephone interviews. Primary outcomes that were measured included emotional and physical health, activity limitation, ambulation, and global health. Measures used included the 36-Item Short Form Health Survey (SF-36), Patient-Reported Outcomes Measurement Information System (PROMIS) Global Health, and Sickness Impact Profile Ambulation. The functional outcomes in our study sample were compared with age- and gender-matched norms from a general US population, and 95% CIs were calculated for each functional outcome mean. Student t test was used for continuous variables, and χ2 analysis was used for categorical variables. Results: Thirty-one of 41 eligible patients were reached for interview. The average age at surgery was 39.7 years. Clinical and radiographic follow-up was a mean of 51.6 months and 31.2 months following TAA, respectively. General health as measured with the SF-36 was not significantly different from age-/gender-matched norms. Eighty-seven percent of patients would choose to have a TAA again. Although 58% reported being limited in vigorous activities, 61% were able to ambulate frequently for long periods of time. On average, the patients did not report ongoing pain, and only 16% reported fatigue that hindered activities. Eighty-one percent reported returning to full employment and performing their duties without difficulty, and 84% reported they resumed all normal social activities. Primary implant survivorship was 93%. Conclusion: Despite a younger age and potentially increased demands, patients aged \u3c50 years undergoing primary TAA are generally satisfied with their index procedure at a mean follow-up of nearly 5 years. Our findings of positive outcomes on their health and well-being may improve surgeon insight for TAA as an alternative treatment for younger individuals with end-stage ankle arthritis. Level of Evidence: Level IV, case series

An experimental and analytical study of plasma closing switches filled with environmentally friendly gases

In recent years there has been a desire within the pulsed power community to find potential alternative gases to sulphur hexafluoride (SF6) for use within pulsed power systems. Within plasma closing switches (PCSs), the desire to use environmentally friendly gases has come as a result of environmental concerns over the emissions of currently used gases into the atmosphere and contributing to the global warming problem. One of the main issues in finding a suitable replacement gas or gases for use in PCSs is that the performance characteristics of a switch filled with an alternative gas or gas mixture should be comparable to the performance characteristics of conventional SF6-filled switches. The research presented in this paper is an expansion of previous work conducted and forms an experimental and analytical evaluation of breakdown characteristics in two commonly used PCS topologies (a two-electrode self-breakdown switch and a field distortion switch) when filled with different gases (air, oxygen-nitrogen mixtures, argon oxygen mixture, nitrogen and carbon dioxide) over a range of pressures from 0.1 MPa to 0.45 MPa and for a range of inter-electrode distances

Management options for the South Australian rock lobster fishery (Jasus edwardsii) fishery: a case study of co-operative assessment and policy design by fishers and biologists

A modelling workshop process was used to bring biologists and commercial fishers together to develop a spatial model for population dynamics and harvest regulation of the South Australian rock lobster (Jasus edwardsii) fishery. The resulting model provided a credible reconstruction of how the space, time, and size structures of the stock have changed over the history of the fishery, and offers a rich variety of regulatory policy options for exploration of how the stock might have behaved (and might behave in the future) if managed differently. Initial use of the model has been to test options for reducing risk of recruitment overfishing by increasing spawning stock and egg production. A number of regulations ranging from increased size limits to large spatial refuges could accomplish this risk reduction aim. One option is to simply reduce the fishing season length dramatically. The model predicts that short-term yield loss under this strategy would eventually be regained through increased survival and higher catch rates of larger lobsters, and offers the economic advantage of greatly reduced fishing costs. This policy hypothesis can be tested in the field by a management experiment allowing fishers to see for themselves whether an area with a short season does indeed result in catch rates high enough to compensate for fishing time loss

Layering methodological tools to represent classroom collectivity

Our research is guided by the question: “How might we observe, document, display, and analyze data from a collective systems perspective?” In this research forum, we share new research tools for studying mathematics classrooms, highlight opportunities for observation and analysis by layering these tools, and then illustrate how the layering of tools allows for visual distinctions across lessons and classrooms.Research was supported by the Social Sciences and Humanities Research Council of Canada

Statistical mechanics of voting

Decision procedures aggregating the preferences of multiple agents can produce cycles and hence outcomes which have been described heuristically as `chaotic'. We make this description precise by constructing an explicit dynamical system from the agents' preferences and a voting rule. The dynamics form a one dimensional statistical mechanics model; this suggests the use of the topological entropy to quantify the complexity of the system. We formulate natural political/social questions about the expected complexity of a voting rule and degree of cohesion/diversity among agents in terms of random matrix models---ensembles of statistical mechanics models---and compute quantitative answers in some representative cases.Comment: 9 pages, plain TeX, 2 PostScript figures included with epsf.tex (ignore the under/overfull \vbox error messages

A tagging SNP in INSIG2 is associated with obesity-related phenotypes among Samoans

<p>Abstract</p> <p>Background</p> <p>A genome wide association study found significant association of a sequence variant, rs7566605, in the insulin-induced gene 2 (<it>INSIG2</it>) with obesity. However, the association remained inconclusive in follow-up studies. We tested for association of four tagging SNPs (tagSNPs) including this variant with body mass index (BMI) and abdominal circumference (ABDCIR) in the Samoans of the Western Pacific, a population with high levels of obesity.</p> <p>Methods</p> <p>We studied 907 adult Samoan participants from a longitudinal study of adiposity and cardiovascular disease risk in two polities, American Samoa and Samoa. Four tagSNPs were identified from the Chinese HapMap database based on pairwise <it>r</it>^{<it>2 </it>}of ≥0.8 and minor allele frequency of ≥0.05. Genotyping was performed using the TaqMan assay. Tests of association with BMI and ABDCIR were performed under the additive model.</p> <p>Results</p> <p>We did not find association of rs7566605 with either BMI or ABDCIR in any group of the Samoans. However, the most distally located tagSNPs in Intron 3 of the gene, rs9308762, showed significant association with both BMI (p-value 0.024) and ABDCIR (p-value 0.009) in the combined sample and with BMI (p-value 0.038) in the sample from Samoa.</p> <p>Conclusion</p> <p>Although rs7566605 was not significantly associated with obesity in our study population, we can not rule out the involvement of <it>INSIG2 </it>in obesity related traits as we found significant association of another tagSNP in <it>INSIG2 </it>with both BMI and ABDCIR. This study suggests the importance of comprehensive assessment of sequence variants within a gene in association studies.</p