Building and using semiparametric tolerance regions for parametric multinomial models

We introduce a semiparametric ``tubular neighborhood'' of a parametric model in the multinomial setting. It consists of all multinomial distributions lying in a distance-based neighborhood of the parametric model of interest. Fitting such a tubular model allows one to use a parametric model while treating it as an approximation to the true distribution. In this paper, the Kullback--Leibler distance is used to build the tubular region. Based on this idea one can define the distance between the true multinomial distribution and the parametric model to be the index of fit. The paper develops a likelihood ratio test procedure for testing the magnitude of the index. A semiparametric bootstrap method is implemented to better approximate the distribution of the LRT statistic. The approximation permits more accurate construction of a lower confidence limit for the model fitting index.Comment: Published in at http://dx.doi.org/10.1214/08-AOS603 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

The topography of multivariate normal mixtures

Multivariate normal mixtures provide a flexible method of fitting high-dimensional data. It is shown that their topography, in the sense of their key features as a density, can be analyzed rigorously in lower dimensions by use of a ridgeline manifold that contains all critical points, as well as the ridges of the density. A plot of the elevations on the ridgeline shows the key features of the mixed density. In addition, by use of the ridgeline, we uncover a function that determines the number of modes of the mixed density when there are two components being mixed. A followup analysis then gives a curvature function that can be used to prove a set of modality theorems.Comment: Published at http://dx.doi.org/10.1214/009053605000000417 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Quality of life in people with Type 2 diabetes in relation to deprivation, gender, and age in a new community-based model of care

Objectives. To evaluate changes in health related quality of life (HRQL) for individuals with Type 2 diabetes following the introduction of a new community-based model of care. Methods. A survey method was used in which HRQL, Problems Areas In Diabetes (PAID) and demographics were assessed before and 18 months after introducing the new service. Results. Overall HRQL and PAID scores were lower than published levels in individuals with diabetes but remained stable during the transition to the new model of care except for the bodily pain domain and deteriorating PAID scores for older patients. Four domains of SF36 health showed deterioration in the highest socio-economic groups. Deterioration was also observed in males, most notably mental health, in patients aged 54 years or less, 75 years or more and patients from socio-economic groups 1 and 2. HRQL was lowest at baseline and follow-up in socio-economic groups 6 and 7. Low levels of distress in patients across all deprivation categories was observed but remained stable over the transition. Conclusions. HRQL and distress associated with diabetes remained stable following the introduction of the new community-based model of care except for deterioration in the bodily pain domain and deteriorating PAID scores for older patients. Relevance for Practice. (i) Health related quality of life assessment is practical and acceptable to patients. (ii) In clinical governance terms it is good practice to monitor the impact of change in service delivery on the health of the patients in your care. (iii) Screening with health related quality of life tools such as generic and disease specific tools could help identify health problems otherwise undetected within current clinical care. Systematic identification of the most vulnerable groups with Type 2 diabetes should allow care to be better targeted

The peacebuilding potential of healthcare training programs.

Global health professionals regularly conduct healthcare trainings, such as first aid courses, in disadvantaged communities across the world. Many of these communities lack healthcare infrastructure because of war and political conflict. The authors draw on their experience conducting a first aid course in South Sudan to provide a perspective on how healthcare trainings for people with no medical background can be used to bridge ethnic, political, and religious differences. They argue that a necessary step for turning a healthcare training into a vehicle for peacebuilding is to bring people from different communities to the same physical space to learn the course material together. Importantly, simply encouraging contact between communities is unlikely to improve intergroup relations and could be detrimental if the following features are not incorporated. Buy-in from respected community leaders is essential to ensure that training participants trust that their safety during the training sessions is not at risk. Trainers should also create a supportive environment by conferring equal status and respect on all trainees. Finally, hands-on training exercises allow for positive interactions between trainees from different groups, which in turn can challenge stereotypes and facilitate cross-group friendships. These features map onto social psychological principles that have been shown to improve intergroup relations and are consistent with lessons learned from peace through health initiatives in public health and medicine. By adopting peacebuilding features, healthcare trainings can serve their primary goal of medical education and provide the added benefit of strengthening social relations

Estimating the number of classes

Estimating the unknown number of classes in a population has numerous important applications. In a Poisson mixture model, the problem is reduced to estimating the odds that a class is undetected in a sample. The discontinuity of the odds prevents the existence of locally unbiased and informative estimators and restricts confidence intervals to be one-sided. Confidence intervals for the number of classes are also necessarily one-sided. A sequence of lower bounds to the odds is developed and used to define pseudo maximum likelihood estimators for the number of classes.Comment: Published at http://dx.doi.org/10.1214/009053606000001280 in the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Quantum stochastic convolution cocycles II

Schuermann's theory of quantum Levy processes, and more generally the theory of quantum stochastic convolution cocycles, is extended to the topological context of compact quantum groups and operator space coalgebras. Quantum stochastic convolution cocycles on a C*-hyperbialgebra, which are Markov-regular, completely positive and contractive, are shown to satisfy coalgebraic quantum stochastic differential equations with completely bounded coefficients, and the structure of their stochastic generators is obtained. Automatic complete boundedness of a class of derivations is established, leading to a characterisation of the stochastic generators of *-homomorphic convolution cocycles on a C*-bialgebra. Two tentative definitions of quantum Levy process on a compact quantum group are given and, with respect to both of these, it is shown that an equivalent process on Fock space may be reconstructed from the generator of the quantum Levy process. In the examples presented, connection to the algebraic theory is emphasised by a focus on full compact quantum groups.Comment: 32 pages, expanded introduction and updated references. The revised version will appear in Communications in Mathematical Physic

‘Riding the waves’ - an exploration of how students undertaking a pre-registration nursing programme develop emotional resilience

Background The study was prompted by recognition of the many emotional demands and challenges on mature students undertaking professional qualifying programmes. These can cause excessive levels of stress and anxiety with an impact on retention of students on programmes. Aim and objectives The overall aim was to identify what pre-registration nurses identified as challenges or adversity in their transition from health care support workers to accountable professionals and what factors they perceived as significant in contributing to their own emotional resilience. The objective was then to make specific recommendations related to the nursing curriculum, academic and work based support structures in order to promote resilience. Participants Participants were pre-registration nursing students on adult and mental health branches nearing the end of their final year of a pre-registration nursing programme with the Open University. Methods A qualitative methodology was used with use of one focus group and eleven in depth interviews. Results Four different dimensions of resilience were identified; ways of being/personal characteristics, personal survival tactics, immediate social and work based environment and wider social and cultural environment. Key findings included the importance of peer support, positive feedback and enhancing the student’s ability to re-frame difficulties or problems, a positive culture of work place learning , supporting and validating personal reflection outside academic discourses, and support in ‘meaning making’. As well as peer support, examples of good practice demonstrated by mentors, programme tutors and tutors were essential in supporting students in these identified areas. Conclusion and recommendations Emotional resilience is a multi-dimensional concept and different levels of intervention are therefore needed to promote it. The curriculum needs to reflect the importance of affective as well as cognitive aspects of development in order to promote the resilience of students and support structures need to be embedded in programme design to promote peer interaction and sharing of good practice between those in education roles. Key words Pre-registration nursing education, emotional resilience, adversity, communities of practic

Quantum stochastic convolution cocycles III

Every Markov-regular quantum Levy process on a multiplier C*-bialgebra is shown to be equivalent to one governed by a quantum stochastic differential equation, and the generating functionals of norm-continuous convolution semigroups on a multiplier C*-bialgebra are then completely characterised. These results are achieved by extending the theory of quantum Levy processes on a compact quantum group, and more generally quantum stochastic convolution cocycles on a C*-bialgebra, to locally compact quantum groups and multiplier C*-bialgebras. Strict extension results obtained by Kustermans, together with automatic strictness properties developed here, are exploited to obtain existence and uniqueness for coalgebraic quantum stochastic differential equations in this setting. Then, working in the universal enveloping von Neumann bialgebra, we characterise the stochastic generators of Markov-regular, *-homomorphic (respectively completely positive and contractive), quantum stochastic convolution cocycles.Comment: 20 pages; v2 corrects some typos and no longer contains a section on quantum random walk approximations, which will now appear as a separate submission. The article will appear in the Mathematische Annale

Clonal Complexes in Biomedical Ontologies

An accurate classification of bacteria is essential for the proper identification of patient infections and subsequent treatment decisions. Multi-Locus Se-quence Typing (MLST) is a genetic technique for bacterial classification. MLST classifications are used to cluster bacteria into clonal complexes. Importantly, clonal complexes can serve as a biological species concept for bacteria, facilitating an otherwise difficult taxonomic classification. In this paper, we argue for the inclusion of terms relating to clonal complexes in biomedical ontologies