Conditions for rapid mixing of parallel and simulated tempering on multimodal distributions

We give conditions under which a Markov chain constructed via parallel or simulated tempering is guaranteed to be rapidly mixing, which are applicable to a wide range of multimodal distributions arising in Bayesian statistical inference and statistical mechanics. We provide lower bounds on the spectral gaps of parallel and simulated tempering. These bounds imply a single set of sufficient conditions for rapid mixing of both techniques. A direct consequence of our results is rapid mixing of parallel and simulated tempering for several normal mixture models, and for the mean-field Ising model.Comment: Published in at http://dx.doi.org/10.1214/08-AAP555 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

Multiple phase transitions in an agent-based evolutionary model with neutral fitness

Null models are crucial for understanding evolutionary processes such as speciation and adaptive radiation. We analyse an agent-based null model, considering a case without selection—neutral evolution—in which organisms are defined only by phenotype. Universal dynamics has previously been demonstrated in a related model on a neutral fitness landscape, showing that this system belongs to the directed percolation (DP) universality class. The traditional null condition of neutral fitness (where fitness is defined as the number of offspring each organism produces) is extended here to include equal probability of death among organisms. We identify two types of phase transition: (i) a non-equilibrium DP transition through generational time (i.e. survival), and (ii) an equilibrium ordinary percolation transition through the phenotype space (based on links between mating organisms). Owing to the dynamical rules of the DP reaction–diffusion process, organisms can only sparsely fill the phenotype space, resulting in significant phenotypic diversity within a cluster of mating organisms. This highlights the necessity of understanding hierarchical evolutionary relationships, rather than merely developing taxonomies based on phenotypic similarity, in order to develop models that can explain phylogenetic patterns found in the fossil record or to make hypotheses for the incomplete fossil record of deep time

Assuring positive impacts from participation with marginalised young people and the services that affect them

Participation has been defined as a ‘way of working’ rather than an event or a project, and literature demonstrates that the process of participating is as important as the impact on services. Many organisations have developed standards advising on the best ways to engage young people in sharing their voices. There is however, limited evidence revealing the impact of participation on services and on those young people who chose to take part. Where evidence does exist it tends to examine the views and report the outcomes of young people engaged in mainstream services. This study therefore aims to explore the impacts of participation on ‘marginalised’ young people and the services that affect them. The thesis is underpinned by a hermeneutic interpretive phenomenological approach and reveals how young people marginalised by society and circumstance can share their voices within the context of their very complex lives. The narrative method enables the capture of the young people’s histories and experiences of voice sharing. Key workers’ narratives additionally help describe the complexity of the young people’s lives and the constraining and enabling factors challenging successful participation. The research found that whilst participation is important in developing and improving services, young people appear to develop new skills, build confidence and self esteem, raise their aspirations and role model key workers’ positive attributes. Young people experience ‘therapeutic’ effects associated with voice sharing and for key workers the research experience was found to be beneficial and salutary. To facilitate and sustain meaningful, fulfilling and positive experiences a new model of participation generated from the data is presented

The k-epsilon model in the theory of turbulence

We consider the $k-varepsilon$ model in the theory of turbulence, where $k$ is the turbulent kinetic energy, $varepsilon$ is thedissipation rate of the turbulent energy, and $alpha,$ $eta,$ and $gamma$ are positive constants. In particular we examine the Barenblatt self-similar $k-varepsilon$ model, along with boundary conditions taken to ensure the symmetry and compactness of the support of solutions.Under the assumptions:$eta>alpha,$ $3alpha>2eta,$ and $gamma$>3/2,we show the existence of $mu$ for which there is a positive solutionto the system and corresponding boundary conditions by proving a seriesof lemmas. We also include graphs of solutions obtained by using XPPAUT 5.85

Confirmatory factor analysis and invariance testing between Blacks and Whites of the Multidimensional Health Locus of Control scale.

The factor structure of the Multidimensional Health Locus of Control scale remains in question. Additionally, research on health belief differences between Black and White respondents suggests that the Multidimensional Health Locus of Control scale may not be invariant. We reviewed the literature regarding the latent variable structure of the Multidimensional Health Locus of Control scale, used confirmatory factor analysis to confirm the three-factor structure of the Multidimensional Health Locus of Control, and analyzed between-group differences in the Multidimensional Health Locus of Control structure and means across Black and White respondents. Our results indicate differences in means and structure, indicating more research is needed to inform decisions regarding whether and how to deploy the Multidimensional Health Locus of Control appropriately

Necrotizing Infiltrative Lipomatosis in a Miniature Zebu Bull (Bos primigenius indicus)

Lipomatosis is described in a miniature Zebu, Bos primigenius indicus, bull that died of perianesthetic complications. This is the first pathologic description of lipomatosis that we are aware of in this species and breed of cattle. Infiltration of multiple visceral organs is described and depicted along with comparison to previously published cases of lipomatosis in other breeds of cattle

ALL CITIES ARE DIFFERENT: Moving creative workforce research forward to a new specificity

The cultural sector and its workforce are often positioned as economic drivers, and important themes within this discourse have included relationships between the cultural sector and human capital, urban regeneration, community engagement, branding, and image. Little of the research underpinning these arguments has documented the work practices, orientations, attitudes, career trajectories and skill requirements of individual creative workers, and even less has considered the spatially specific nature of labour conditions and career trajectories to produce a differentiated analysis of work and career. What happens within any locality over time will partially result from the changing roles it plays within the broader spatial divisions of labour within which it is emplaced. However, we argue that it is insufficient to claim that all cities are different; rather, there is a need to examine the specificity of work in each location.In this paper, the second in a series that examine specific elements of creative work, we consider spatiality with specific reference to the use of networks. Drawing on a case study of the film and television industries in Perth we raise the possibility of approaching such research by combining the global production network approach, labour process analysis, and research that looks within individual practice

A Cross-Sectional Analysis of the Association between Physical Activity and Visceral Adipose Tissue Accumulation in a Multiethnic Cohort

Higher levels of VAT at the same body size and lower levels of physical activity (PA) have been reported in persons of Chinese and South Asian origin compared to European origin. The purpose of this study was to test the hypothesis that higher levels of VAT in persons of Chinese and South Asian origin versus European origin are associated with lower levels of PA. Chinese, European, and South Asian participants were assessed for sociodemographics, obesity-related measures, anthropometrics, and PA. Bivariate correlations, analysis of covariance, and regression models were used to explore ethnic differences in PA and the role of PA in explaining obesity-related measures. We observed ethnic differences in both body fat distribution and PA. Chinese and South Asians had higher amounts of VAT at a given BMI but lower amounts of moderate PA, vigorous PA, and moderate-to-vigorous PA (MVPA). Furthermore, we found ethnic-specific differences in the associations between body fat distribution and PA with only Europeans showing a consistent negative relationship between body fat distribution and PA. When ethnic differences in PA were taken into account, there were no longer any differences in VAT between the Chinese and European groups, while VAT remained higher in South Asians than Europeans