Sheaf Logic, Quantum Set Theory and the Interpretation of Quantum Mechanics

Based on the Sheaf Logic approach to set theoretic forcing, a hierarchy of Quantum Variable Sets is constructed which generalizes and simplifies the analogous construction developed by Takeuti on boolean valued models of set theory. Over this model two alternative proofs of Takeuti's correspondence, between self adjoint operators and the real numbers of the model, are given. This approach results to be more constructive showing a direct relation with the Gelfand representation theorem, revealing also the importance of these results with respect to the interpretation of Quantum Mechanics in close connection with the Deutsch-Everett multiversal interpretation. Finally, it is shown how in this context the notion of genericity and the corresponding generic model theorem can help to explain the emergence of classicality also in connection with the Deutsch- Everett perspective.Comment: 34 pages, 2 figure

A glossary for the social epidemiology of work organization. Part 3: terms from labour markets

This is part 3 of a three-part glossary on the social epidemiology of work organisation. The first two parts deal with the social psychology of work and with organisations. This concluding part presents concepts related to labour markets. These concepts are drawn from economics, business and sociology. They relate both to traditional interests in these disciplines and to contemporary ideas on post-industrialisation and globalisation, particularly the growth of employment in service industries, the development of a 24-h economy, increased participation of the female labour force and the perceived needs of employers in emerging high-tech economies.These changes are of particular interest because they are linked to increasing inequality in earnings and changes in social relationships in employment. These concepts have the potential to elucidate the pathways through which health is affected by conditions of work as an underlying cause

Psychosocial factors and work related sickness absence among permanent and non-permanent employees

Study objective: To examine the association between psychosocial work factors and work related sickness absence among permanent and non-permanent employees by sex.Design: A cross sectional survey conducted in 2000 of a representative sample of the European Union total active population, aged 15 years and older. The independent variables were psychological job demands and job control as measures of psychosocial work environment, and work related sickness absence as the main outcome. Poisson regression models were used to compute sickness absence days' rate ratios.Setting: 15 countries of the European Union.Participants: A sample of permanent (n=12875) and non-permanent (n=1203) workers from the Third European Survey on Working Conditions.Results: High psychological job demands, low job control, and high strain and passive work were associated with higher work related sickness absence. The risks were more pronounced in non-permanent compared with permanent employees and men compared with women.Conclusions: This work extends previous research on employment contracts and sickness absence, suggesting different effects depending on psychosocial working conditions and sex

Perturbation theory for very long-range potentials

Systems with very long-range interactions (that decay at large distances like $U(r)\sim r^{-l}$ with $l\le d$ where $d$ is the space dimensionality) are difficult to study by conventional statistical mechanics perturbation methods. Examples of these systems are gravitational and charged (non-electroneutral). In this work we propose two alternative methodologies to avoid these difficulties and capture some of the properties of the original potential. The first one consists in expressing the original potential in terms of a finite sum of hard-core Yukawa potentials. In the second one, the potential is rewritten as a damped potential, using a damping function with a parameter that controls the range of the interaction. These new potentials, which mimic the original one, can now be treated by conventional statistical mechanics methods.Comment: 25 pages, 11 figure

Mutation testing on an object-oriented framework: An experience report

This is the preprint version of the article - Copyright @ 2011 ElsevierContext The increasing presence of Object-Oriented (OO) programs in industrial systems is progressively drawing the attention of mutation researchers toward this paradigm. However, while the number of research contributions in this topic is plentiful, the number of empirical results is still marginal and mostly provided by researchers rather than practitioners. Objective This article reports our experience using mutation testing to measure the effectiveness of an automated test data generator from a user perspective. Method In our study, we applied both traditional and class-level mutation operators to FaMa, an open source Java framework currently being used for research and commercial purposes. We also compared and contrasted our results with the data obtained from some motivating faults found in the literature and two real tools for the analysis of feature models, FaMa and SPLOT. Results Our results are summarized in a number of lessons learned supporting previous isolated results as well as new findings that hopefully will motivate further research in the field. Conclusion We conclude that mutation testing is an effective and affordable technique to measure the effectiveness of test mechanisms in OO systems. We found, however, several practical limitations in current tool support that should be addressed to facilitate the work of testers. We also missed specific techniques and tools to apply mutation testing at the system level.This work has been partially supported by the European Commission (FEDER) and Spanish Government under CICYT Project SETI (TIN2009-07366) and the Andalusian Government Projects ISABEL (TIC-2533) and THEOS (TIC-5906)

How to Complete an Interactive Configuration Process?

When configuring customizable software, it is useful to provide interactive tool-support that ensures that the configuration does not breach given constraints. But, when is a configuration complete and how can the tool help the user to complete it? We formalize this problem and relate it to concepts from non-monotonic reasoning well researched in Artificial Intelligence. The results are interesting for both practitioners and theoreticians. Practitioners will find a technique facilitating an interactive configuration process and experiments supporting feasibility of the approach. Theoreticians will find links between well-known formal concepts and a concrete practical application.Comment: to appear in SOFSEM 201

Model for transitional turbulence in a planar shear flow

A central obstacle to understanding the route to turbulence in wall-bounded flows is that the flows are composed of complex, highly fluctuating, and strongly nonlinear states. We address this challenge by deriving from the Navier-Stokes equations a simplified model that describes transitional turbulence in a planar setting. The Reynolds-averaged and turbulent-kinetic-energy equations are projected onto a minimal set of wall-normal modes and justified model closures are used for the Reynolds stresses and turbulent dissipation and transport. The model reproduces the oblique turbulent-laminar patterns ubiquitous in wall-bounded shear flows. It also captures the pattern wavelengths and angles, and the large-scale flow associated with both stationary patterns and growing turbulent spots. Patterns are shown to arise with decreasing Reynolds number via a linear instability of uniform turbulence. Linear analysis reveals implications for the critical angle at onset.Comment: 6 page in the main text; 3 figures. 25 pages in the Supplemental Material; 2 figure