Quivers and Three-Dimensional Lie Algebras

We study a family of three-dimensional Lie algebras $L_\mu$ that depend on a continuous parameter $\mu$. We introduce certain quivers, which we denote by $Q_{m,n}$ $(m,n \in \mathbb{Z})$ and $Q_{\infty \times \infty}$, and prove that idempotented versions of the enveloping algebras of the Lie algebras $L_{\mu}$ are isomorphic to the path algebras of these quivers modulo certain ideals in the case that $\mu$ is rational and non-rational, respectively. We then show how the representation theory of the quivers $Q_{m,n}$ and $Q_{\infty\times\infty}$ can be related to the representation theory of quivers of affine type $A$, and use this relationship to study representations of the Lie algebras $L_\mu$. In particular, though it is known that the Lie algebras $L_\mu$ are of wild representation type, we show that if we impose certain restrictions on weight decompositions, we obtain full subcategories of the category of representations of $L_\mu$ that are of finite or tame representation type.Comment: 18 page

Globalization and its methodological discontents: Contextualizing globalization through the study of HIV/AIDS

There remains considerable discontent between globalization scholars about how to conceptualize its meaning and in regards to epistemological and methodological questions concerning how we can come to understand how these processes ultimately operate, intersect and transform our lives. This article argues that to better understand what globalization is and how it affects issues such as global health, we must take a differentiating approach, which focuses on how the multiple processes of globalization are encountered and informed by different social groups and with how these encounters are experienced within particular contexts. The article examines the heuristic properties of qualitative field research as a means to help better understand how the intersections of globalization are manifested within particular locations. To do so, the article focuses on three recent case studies conducted on globalization and HIV/AIDS and explores how these cases can help us to understand the contextual permutations involved within the processes of globalization

Identifying factors likely to influence compliance with diagnostic imaging guideline recommendations for spine disorders among chiropractors in North America: a focus group study using the Theoretical Domains Framework

Background: The Theoretical Domains Framework (TDF) was developed to investigate determinants of specific clinical behaviors and inform the design of interventions to change professional behavior. This framework was used to explore the beliefs of chiropractors in an American Provider Network and two Canadian provinces about their adherence to evidence-based recommendations for spine radiography for uncomplicated back pain. The primary objective of the study was to identify chiropractors’ beliefs about managing uncomplicated back pain without xrays and to explore barriers and facilitators to implementing evidence-based recommendations on lumbar spine xrays. A secondary objective was to compare chiropractors in the United States and Canada on their beliefs regarding the use of spine x-rays. Methods: Six focus groups exploring beliefs about managing back pain without x-rays were conducted with a purposive sample. The interview guide was based upon the TDF. Focus groups were digitally recorded, transcribed verbatim, and analyzed by two independent assessors using thematic content analysis based on the TDF. Results: Five domains were identified as likely relevant. Key beliefs within these domains included the following: conflicting comments about the potential consequences of not ordering x-rays (risk of missing a pathology, avoiding adverse treatment effects, risks of litigation, determining the treatment plan, and using x-ray-driven techniques contrasted with perceived benefits of minimizing patient radiation exposure and reducing costs; beliefs about consequences); beliefs regarding professional autonomy, professional credibility, lack of standardization, and agreement with guidelines widely varied (social/professional role & identity); the influence of formal training, colleagues, and patients also appeared to be important factors (social influences); conflicting comments regarding levels of confidence and comfort in managing patients without x-rays (belief about capabilities); and guideline awareness and agreements (knowledge). Conclusions: Chiropractors’ use of diagnostic imaging appears to be influenced by a number of factors. Five key domains may be important considering the presence of conflicting beliefs, evidence of strong beliefs likely to impact the behavior of interest, and high frequency of beliefs. The results will inform the development of a theorybased survey to help identify potential targets for behavioral-change strategies

Empirical Bayes estimation of posterior probabilities of enrichment

To interpret differentially expressed genes or other discovered features, researchers conduct hypothesis tests to determine which biological categories such as those of the Gene Ontology (GO) are enriched in the sense of having differential representation among the discovered features. We study application of better estimators of the local false discovery rate (LFDR), a probability that the biological category has equivalent representation among the preselected features. We identified three promising estimators of the LFDR for detecting differential representation: a semiparametric estimator (SPE), a normalized maximum likelihood estimator (NMLE), and a maximum likelihood estimator (MLE). We found that the MLE performs at least as well as the SPE for on the order of 100 of GO categories even when the ideal number of components in its underlying mixture model is unknown. However, the MLE is unreliable when the number of GO categories is small compared to the number of PMM components. Thus, if the number of categories is on the order of 10, the SPE is a more reliable LFDR estimator. The NMLE depends not only on the data but also on a specified value of the prior probability of differential representation. It is therefore an appropriate LFDR estimator only when the number of GO categories is too small for application of the other methods. For enrichment detection, we recommend estimating the LFDR by the MLE given at least a medium number (~100) of GO categories, by the SPE given a small number of GO categories (~10), and by the NMLE given a very small number (~1) of GO categories.Comment: exhaustive revision of Zhenyu Yang and David R. Bickel, "Minimum Description Length Measures of Evidence for Enrichment" (December 2010). COBRA Preprint Series. Article 76. http://biostats.bepress.com/cobra/ps/art7

Instrument development, data collection, and characteristics of practices, staff, and measures in the Improving Quality of Care in Diabetes (iQuaD) Study

Peer reviewedPublisher PD

Coherent frequentism

By representing the range of fair betting odds according to a pair of confidence set estimators, dual probability measures on parameter space called frequentist posteriors secure the coherence of subjective inference without any prior distribution. The closure of the set of expected losses corresponding to the dual frequentist posteriors constrains decisions without arbitrarily forcing optimization under all circumstances. This decision theory reduces to those that maximize expected utility when the pair of frequentist posteriors is induced by an exact or approximate confidence set estimator or when an automatic reduction rule is applied to the pair. In such cases, the resulting frequentist posterior is coherent in the sense that, as a probability distribution of the parameter of interest, it satisfies the axioms of the decision-theoretic and logic-theoretic systems typically cited in support of the Bayesian posterior. Unlike the p-value, the confidence level of an interval hypothesis derived from such a measure is suitable as an estimator of the indicator of hypothesis truth since it converges in sample-space probability to 1 if the hypothesis is true or to 0 otherwise under general conditions.Comment: The confidence-measure theory of inference and decision is explicitly extended to vector parameters of interest. The derivation of upper and lower confidence levels from valid and nonconservative set estimators is formalize

Continence Across Continents To Upend Stigma and Dependency (CACTUS-D): study protocol for a cluster randomized controlled trial

Background: Urinary incontinence occurs in 40 % of women aged 65 years and over; however, only 15 % seek care and many delay healthcare seeking for years. Incontinence is associated with depression, social isolation, reduced quality of life, falls and other comorbidities. It is accompanied by an enormous cost to the individual and society. Despite the substantial implications of urinary incontinence on social, psychological and physical well-being of older women, the impact of continence promotion on urinary symptom improvement and subsequent effects on falls, quality of life, stigma, social participation and the cost of care remains unknown. Methods: This study is a mixed methods multi-national open-label 2-arm parallel cluster randomized controlled trial aiming to recruit 1000 community-dwelling incontinent women aged 65 years and older across Quebec, Western Canada, France and United Kingdom. Participants will be recruited through community organizations. Data will be collected at 6 time points: baseline and 1 week, 3 months, 6 months, 9 months and 12 months after baseline. One of the primary objectives is to evaluate whether the continence promotion intervention improves incontinence symptoms (measured with the Patient Global Impression of Improvement questionnaire, PGI-I) at 12 months post intervention compared to the control group. Other co-primary outcomes include changes in incontinence-related stigma, fall reduction, and incremental cost-effectiveness ratio and quality-adjusted life years. Data analysis will account for correlation of outcomes (clustering) within community organizations. A qualitative sub-study will explore stigma reduction. Discussion: Community-based continence promotion programs may be a cost-effective strategy to reduce urinary incontinence, stigma and falls among older women with untreated incontinence, and simultaneously improve quality of life and healthy active life expectancy.European Research Area on Ageing2 (ERA-AGE2) progra

A systematic review of how studies describe educational interventions for evidence-based practice:Stage 1 of the development of a reporting guideline

Abstract Background The aim of this systematic review was to identify which information is included when reporting educational interventions used to facilitate foundational skills and knowledge of evidence-based practice (EBP) training for health professionals. This systematic review comprised the first stage in the three stage development process for a reporting guideline for educational interventions for EBP. Methods The review question was ‘What information has been reported when describing educational interventions targeting foundational evidence-based practice knowledge and skills?’ MEDLINE, Academic Search Premier, ERIC, CINAHL, Scopus, Embase, Informit health, Cochrane Library and Web of Science databases were searched from inception until October - December 2011. Randomised and non-randomised controlled trials reporting original data on educational interventions specific to developing foundational knowledge and skills of evidence-based practice were included. Studies were not appraised for methodological bias, however, reporting frequency and item commonality were compared between a random selection of studies included in the systematic review and a random selection of studies excluded as they were not controlled trials. Twenty-five data items were extracted by two independent reviewers (consistency > 90%). Results Sixty-one studies met the inclusion criteria (n = 29 randomised, n = 32 non-randomised). The most consistently reported items were the learner’s stage of training, professional discipline and the evaluation methods used (100%). The least consistently reported items were the instructor(s) previous teaching experience (n = 8, 13%), and student effort outside face to face contact (n = 1, 2%). Conclusion This systematic review demonstrates inconsistencies in describing educational interventions for EBP in randomised and non-randomised trials. To enable educational interventions to be replicable and comparable, improvements in the reporting for educational interventions for EBP are required. In the absence of a specific reporting guideline, there are a range of items which are reported with variable frequency. Identifying the important items for describing educational interventions for facilitating foundational knowledge and skills in EBP remains to be determined. The findings of this systematic review will be used to inform the next stage in the development of a reporting guideline for educational interventions for EBP

Study protocol : the empirical investigation of methods to correct for measurement error in biobanks with dietary assessment

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The use of segmented regression in analysing interrupted time series studies : an example in pre-hospital ambulance care

Peer reviewedPublisher PD