A parallel edge orientation algorithm for quadrilateral meshes

One approach to achieving correct finite element assembly is to ensure that the local orientation of facets relative to each cell in the mesh is consistent with the global orientation of that facet. Rognes et al. have shown how to achieve this for any mesh composed of simplex elements, and deal.II contains a serial algorithm to construct a consistent orientation of any quadrilateral mesh of an orientable manifold. The core contribution of this paper is the extension of this algorithm for distributed memory parallel computers, which facilitates its seamless application as part of a parallel simulation system. Furthermore, our analysis establishes a link between the well-known Union-Find algorithm and the construction of a consistent orientation of a quadrilateral mesh. As a result, existing work on the parallelisation of the Union-Find algorithm can be easily adapted to construct further parallel algorithms for mesh orientations.Comment: Second revision: minor change

Neighbourhood mobility in context : household moves and changing neighbourhoods in the Netherlands

Although high levels of population mobility are often viewed as a problem at the neighbourhood level we know relatively little about what makes some neighbourhoods more mobile than others. The main question in this paper is to what extent differences in out-mobility between neighbourhoods can be explained by differences in the share of mobile residents, or whether other neighbourhood characteristics also play a role. To answer this question we focus on the effects of the socioeconomic status and ethnic composition of neighbourhoods and on neighbourhood change. Using data from the Netherlands population registration system and the Housing Demand Survey we model population mobility both at individual and at neighbourhood levels. The aggregate results show that the composition of the housing stock and of the neighbourhood population explain most of the variation in levels of neighbourhood out-mobility. At the same time, although ethnic minority groups in the Netherlands are shown to be relatively immobile, neighbourhoods with higher concentrations of ethnic minority residents have the highest population turnovers. The individual-level models show that people living in neighbourhoods which experience an increase in the percentage of ethnic minorities are more likely to move, except when they belong to an ethnic minority group themselves. The evidence suggests that 'white flight' and 'socio-economic flight' are important factors in neighbourhood change.PostprintPeer reviewe

Identification of functional information subgraphs in complex networks

We present a general information theoretic approach for identifying functional subgraphs in complex networks where the dynamics of each node are observable. We show that the uncertainty in the state of each node can be expressed as a sum of information quantities involving a growing number of correlated variables at other nodes. We demonstrate that each term in this sum is generated by successively conditioning mutual informations on new measured variables, in a way analogous to a discrete differential calculus. The analogy to a Taylor series suggests efficient search algorithms for determining the state of a target variable in terms of functional groups of other degrees of freedom. We apply this methodology to electrophysiological recordings of networks of cortical neurons grown it in vitro. Despite strong stochasticity, we show that each cell's patterns of firing are generally explained by the activity of a small number of other neurons. We identify these neuronal subgraphs in terms of their mutually redundant or synergetic character and reconstruct neuronal circuits that account for the state of each target cell.Comment: 4 pages, 4 figure

Does Migration Make You Happy?:A Longitudinal Study of Internal Migration and Subjective Well-Being

The majority of modelling studies on consequences of internal migration focus almost exclusively on the labour market outcomes and the material well-being of migrants. We investigate whether individuals who migrate within the UK become happier after the move than they were before it and whether the effect is permanent or transient. Using life satisfaction responses from 12 waves of the British Household Panel Survey (BHPS) and employing a fixed-effects model, we derive a temporal pattern of migrants’ subjective wellbeing (SWB) around the time of the migration event. Our findings make an original contribution by revealing for the first time that, on average, migration is preceded by a period when individuals experience a significant decline in happiness. The boost that is received through migration appears to bring people back to their initial level of happiness. As opposed to labour market outcomes of migration, SWB outcomes do not differ significantly between men and women. Perhaps surprisingly, long-distance migrants are at least as happy as short-distance migrants despite the higher social costs that are involved

From local laboratory data to public domain database in search of indirect association of diseases: AJAX based gene data search engine.

This paper presents an extensible schema for capturing laboratory gene variance data with its meta-data properties in a semi-structured environment. This paper also focuses on the issues of creating a local and task specific component database which is a subset of global data resources. An XML based genetic disorder component database schema is developed with adequate flexibilities to facilitate searching of gene mutation data. A web based search engine is developed that allows researchers to query a set of gene parameters obtained from local XML schema and subsequently allow them to automatically establish a link with the public domain gene databases. The application applies AJAX (Asynchronous Javascript and XML), a cutting-edge web technology, to carry out the gene data searching function