A new Algorithm Based on Factorization for Heterogeneous Domain Decomposition

Often computational models are too expensive to be solved in the entire domain of simulation, and a cheaper model would suffice away from the main zone of interest. We present for the concrete example of an evolution problem of advection reaction diffusion type a heterogeneous domain decomposition algorithm which allows us to recover a solution that is very close to the solution of the fully viscous problem, but solves only an inviscid problem in parts of the domain. Our new algorithm is based on the factorization of the underlying differential operator, and we therefore call it factorization algorithm. We give a detailed error analysis, and show that we can obtain approximations in the viscous region which are much closer to the viscous solution in the entire domain of simulation than approximations obtained by other heterogeneous domain decomposition algorithms from the literature.Comment: 23 page

Automatically Extracting Instances of Code Change Patterns with AST Analysis

A code change pattern represents a kind of recurrent modification in software. For instance, a known code change pattern consists of the change of the conditional expression of an if statement. Previous work has identified different change patterns. Complementary to the identification and definition of change patterns, the automatic extraction of pattern instances is essential to measure their empirical importance. For example, it enables one to count and compare the number of conditional expression changes in the history of different projects. In this paper we present a novel approach for search patterns instances from software history. Our technique is based on the analysis of Abstract Syntax Trees (AST) files within a given commit. We validate our approach by counting instances of 18 change patterns in 6 open-source Java projects.Comment: ICSM - 29th IEEE International Conference on Software Maintenance (2013

Transcriptional coupling of neighbouring genes and gene expression noise: evidence that gene orientation and non-coding transcripts are modulators of noise

For some genes, notably essential genes, expression when expression is needed is vital hence low noise in expression is favourable. For others noise is necessary for coping with stochasticity or for providing dice-like mechanisms to control cell fate. But how is noise in gene expression modulated? We hypothesise that gene orientation may be crucial, as for divergently organized gene pairs expression of one gene could affect chromatin of a neighbour thereby reducing noise. Transcription of antisense non-coding RNA from a shared promoter is similarly argued to be a noise-reduction mechanism. Stochastic simulation models confirm the expectation. The model correctly predicts: that protein coding genes with bi-promoter architecture, including those with a ncRNA partner, have lower noise than other genes; divergent gene pairs uniquely have correlated expression noise; distance between promoters predicts noise; ncRNA divergent transcripts are associated with genes that a priori would be under selection for low noise; essential genes reside in divergent orientation more than expected; bi-promoter pairs are rare subtelomerically, cluster together and are enriched in essential gene clusters. We conclude that gene orientation and transcription of ncRNAs, even if unstable, are candidate modulators of noise levels

National Security in an Insecure Age

Our only hope of correctly anticipating the future is to consider the past. Yet the apparent pace of change on the strategic scene since the end of the Second World War entails some danger of exaggerating the extent to which the rest of this century will take a novel form

The Use of Naval Forces in Peacetime

If peacetime is defined generously as virtually every state short of all-out war, the use of naval force in such a state presents a subject of immense scope. For, contrary to some of the more alarmist media, peace-if sometimes a little hot-is the normal condition, Armed forces discharge most of their functions without warfare and, indeed, short of the point at which any shooting takes place. This has certainly been a longstanding characteristic of navies

Optimized Schwarz Waveform Relaxation for Advection Reaction Diffusion Equations in Two Dimensions

Optimized Schwarz Waveform Relaxation methods have been developed over the last decade for the parallel solution of evolution problems. They are based on a decomposition in space and an iteration, where only subproblems in space-time need to be solved. Each subproblem can be simulated using an adapted numerical method, for example with local time stepping, or one can even use a different model in different subdomains, which makes these methods very suitable also from a modeling point of view. For rapid convergence however, it is important to use effective transmission conditions between the space-time subdomains, and for best performance, these transmission conditions need to take the physics of the underlying evolution problem into account. The optimization of these transmission conditions leads to a mathematically hard best approximation problem of homographic type. We study in this paper in detail this problem for the case of linear advection reaction diffusion equations in two spatial dimensions. We prove comprehensively best approximation results for transmission conditions of Robin and Ventcel type. We give for each case closed form asymptotic values for the parameters, which guarantee asymptotically best performance of the iterative methods. We finally show extensive numerical experiments, and we measure performance corresponding to our analysisComment: 42 page

VOLUNTARISM AND THE CRIMINAL JUSTICE SYSTEM : A COMPARATIVE ANALYSIS

Merged with duplicate record 10026.1/735 on 14.02.2017 by CS (TIS)This thesis comparatively evaluates three groups of volunteers working within the criminal justice system in the South West of England. The groups chosen - probation Voluntary Associates, police Specials and Victims Support Scheme Volunteers - incorporate parties working with the offender, the public and the victim, ie those most closely identified with the judicial process. To date, research in both Britain and abroad has chosen to focus on a single agency which has limited our understanding of voluntarismo Nevertheless, most have identified a number of issues pertaining to the use of volunteers. Through a consideration of the type of work undertaken, motivations, who volunteers, recruitment, selection and training, and the role of the professional, this thesis attempts to link and examine these issues, to illustrate that it is possible to theorise about voluntary activity in a criminal justice context. Via interviews with 164 volunteers supported by extensive observation it has been possible to gain a more detailed insight into voluntary activity than had previously been contemplated. The findings revealed that within each organisation there. ý exists a volunteer sub-culture, (abbreviated to volunculture), which conforms to the ideology of the agency. Where a volunculture is strong, as in the case of the Specials then commitment is high; where a volunculture is weak commitment is likely to be low. The study moves on to consider the ways in which organisational policy can and does affect not only the formationof-a volunculture, _ but also its degree of strength or weakness. It is shown that presently most organisations pay lip service to the notion of using volunteers, reflected in the low status they are accorded within agency priorities. It is argued that until this is realised the wealth of helping potential that exists within communities can never be brought to the fore. Recommendations derived from volunteer perceptions and organisational policies are offered as pathfinders to achieving this objective

Simulating the transmission of wealth inequality via bequests

Answering the question of how much wealth inequality arises from inheritance inequality requires data that are unavailable and potentially uncollectable. The alternative approach taken here (from Blinder [1974, 1976] and Davies [1982]) is to simulate the transmission of inequality via bequests.Wealth

Simulating the Transmission of Wealth Inequity via Bequests

This paper develops, calibrates, and simulates a dynamic 88-period OLG model to study the intergenerational transmission of U.S. wealth inequality via bequests. The model features marriage, realistic fertility patterns, random death, assortative mating based on skills, heterogeneous skill endowments, heterogeneous rates of return, skill inheritability, progressive income taxation, and resource annuitization via social security. All bequests arise from imperfect annuitization. Nonetheless, the model generates a realistic ration of aggregate wealth to aggregate labor income, a realistic bequest flow relative to the stock of wealth, and a realistic wealth distribution at retirement. Skill differences, assortative mating, social security, and the time preference are the primary determinants of wealth inequality. Bequests do propagate wealth inequality, but only in the presence of social security, which disproportionately disinherits the lifetime poor. Intergenerational wealth immobility, also considered here, is primarily determined by the inheritance of skills from one's parents and the magnification of the impact of this inheritance by marital sorting.