Retirement provision for New Zealand women: The relative role of demographic influence

This research contributes to our knowledge of retirement provision by clarifying the obstacles that women face in relation to old age provision. By using multivariate analysis and therefore by controlling for confounding effects, this study has isolated the particular influence of important socio-economic factors. Through continued participation in the labour market, despite their childbearing roles, and the goal of enhancing the quality of their employment, women have an opportunity to strengthen their ability to provide sufficiently themselves for their own old age but this is still even today not a certainty or a source of unlimited support

On subtrees of the representation tree in rational base numeration systems

International audienc

Run-Based Semantics for RPQs

The formalism of RPQs (regular path queries) is an important building block of most query languages for graph databases. RPQs are generally evaluated under homomorphism semantics; in particular only the endpoints of the matched walks are returned. Practical applications often need the full matched walks to compute aggregate values. In those cases, homomorphism semantics are not suitable since the number of matched walks can be infinite. Hence, graph-database engines adapt the semantics of RPQs, often neglecting theoretical red flags. For instance, the popular query language Cypher uses trail semantics, which ensures the result to be finite at the cost of making computational problems intractable. We propose a new kind of semantics for RPQs, including in particular simple-run and binding-trail semantics, as a candidate to reconcile theoretical considerations with practical aspirations. Both ensure the output to be finite in a way that is compatible with homomorphism semantics: projection on endpoints coincides with homomorphism semantics. Hence, testing the emptiness of result is tractable, and known methods readily apply. Moreover, simple-run and binding-trail semantics support bag semantics, and enumeration of the bag of results is tractableComment: 35 page

Stochastic precession of the polarization in a polariton laser

Microcavity polaritons in the lasing regime undergo a spontaneous symmetry breaking transition resulting in coherent emission with a well defined polarization. The order parameter is thus a vector describing both the laser global phase and polarization. Using an ultrafast single-shot detection technique we show that polariton lasing in GaAs-based microcavities presents a high degree of second order coherence ($g^{(2)}(\tau=0) \approx 1$) above threshold, and that the initial polarization is stochastic, taking any possible direction in the Poincar\'e sphere (linear, elliptical or circular). Once the polarization direction is established, subsequent oscillations of the emission probability witness the presence of an intrinsic polarization splitting. Our results show the negligible role of polariton interactions in the total emission statistics and in the establishment of the initial polarization.Comment: 9 pages, 6 figure

On p/q-recognisable sets

Let p/q be a rational number. Numeration in base p/q is defined by a function that evaluates each finite word over A_p={0,1,...,p-1} to some rational number. We let N_p/q denote the image of this evaluation function. In particular, N_p/q contains all nonnegative integers and the literature on base p/q usually focuses on the set of words that are evaluated to nonnegative integers; it is a rather chaotic language which is not context-free. On the contrary, we study here the subsets of (N_p/q)^d that are p/q-recognisable, i.e. realised by finite automata over (A_p)^d. First, we give a characterisation of these sets as those definable in a first-order logic, similar to the one given by the B\"uchi-Bruy\`ere Theorem for integer bases numeration systems. Second, we show that the natural order relation and the modulo-q operator are not p/q-recognisable

Un modèle de lubrification en régime mixte du laminage : Frottement et lubrification en mise en forme = A mixed lubrication model of the cold strip rolling process

Free access articleInternational audienceLe régime de lubrification mixte est le plus fréquemment rencontré en laminage à froid. Sa modélisation est le but de cet article. La lubrification, phénomène interfacial, est fortement couplée à la mécanique de l'opération de laminage. C'est pourquoi le modèle présenté assemble un modèle macroscopique de laminage (méthode des tranches élasto-plastique) et un modèle microscopique de lubrification en régime mixte, lui-même composé d'une équation de Reynolds entre surfaces rugueuses (formation du film lubrifiant) et d'une équation d'évolution de la rugosité, par conformation de la tôle au cylindre. Les principes du modèle sont présentés, comparés à ceux de la bibliographie, ses hypothèses et ses résultats sont discutés, et quelques applications sont évoquées = The mixed regime of lubrication is most frequently encountered in cold strip rolling processes. A model is presented hereafter. The lubrication at the interface is closely coupled with the mechanics of the rolling process. Therefore, the proposed model combines a macroscopic model of rolling (elastic-plastic slab method) with a microscopic mixed lubrication model, consisting of a Reynolds equation for rough surfaces (describing the formation of the lubricant film) and an equation for the evolution of roughness, describing the conformation of the strip surface to the roll. The bases of the model are presented and compared to models in the literature; its hypotheses and results are discussed, a few applications are given