Are Foster Children Made Better Off by Informal Fostering Arrangements?

Research on the effects of informal child fostering arrangements on the welfare of the children involved highlights cross-country disparities. Why may there be differences across countries with regard to the effects of informal child fostering arrangements? If in all countries reporting a high incidence of foster children Hamilton’s rule applies, then these cross-country differences are puzzling. Our model of child fostering arrangements builds on the fact that a child’s school performance is jointly influenced by his nutrition status and the time he has available at home to develop his learning skills and prepare for national school tests. Given this feature of academic performance, fostering out may become a poor parent’s best option for enhancing his child’s academic excellence, by trading off study time for better nutrition. We show that child fostering arrangements embedding this human capital motive for out-fostering make the foster child better off when nutrition is paramount to a child’s ability to achieve academic excellence.Child fostering, child nutrition, foster child's welfare

Fractal properties and characterization of road profiles

International audienceA major problem in road engineering is to understand the mechanisms of friction between rubber and the road. We study road profiles obtained using tactile and laser captors. these profiles belong to different category characterized by different friction coefficients. We find that all our profiles indeed display strong fractal behaviour in terms of both correlation exponents and regularization dimension over a large range of scales. However, neither of these fractal parameters seem to be related to friction. We then use a local fractal parameter, namely the pointwise Holder exponent. We show that this exponent does discriminate profiles which have different friction properties

Restructurations : Regard sur ses répercussions humaines et organisationnelles

International audienceThis study has been carried out in a multinational company and which is currently undergoing a restructuring. This analysis puts the emphasis on the human and organizational effects generated by this singular context. Drawing on three theoretical concepts, the aim of this study is to check if a degree of " stress perceived " as high associated with an " organizational support perceived " as weak questions the " affective commitment " of the employees leading to bad outcomes for the company in terms of productivity and efficiency. The results confirm our predictions. Indeed, a correlation between a stress perceived as " pathological " , an organizational support perceived as weak and a moderate affective commitment is to be found for the employees surveyed.Réalisée au sein d'une multinationale en restructuration, cette étude met l'accent sur les répercussions humaines et organisationnelles générées par ce contexte singulier. En conjuguant trois concepts théoriques, l'objectif de cette recherche est de vérifier si un " stress perçu " élevé associé à un faible " soutien organisationnel perçu " remet en question " l'implication organisationnelle affective " des salariés, engendrant fatalement des conséquences négatives en termes de productivité et d'efficacité de l'entreprise. Les résultats obtenus confirment nos prédictions, témoignant d'une corrélation entre un stress perçu dit " pathologique " , un faible soutien organisationnel perçu et une implication organisationnelle affective modérée des salariés sondés

Interpolation de signaux par conservation de la régularité Höldérienne

é - On considère le problème de l'interpolation d'un signal dans Rd connu à une certaine résolution. On suppose que le signal appartient à une classe de signaux caractérisée par des contraintes sur la régularité locale, qui peuvent être traduites par un certain comportement inter-échelles des coefficients d'ondelette. Ces contraintes permettent de prédire les coefficients de l'échelle n + 1 à partir de ceux des échelles précédentes. Nous donnons quelques propriétés de cette technique d'interpolation, concernant en particulier la régularité Hôldérienne du signal raffiné et son comportement asymptotique. Les résultats théoriques et numériques montrent que notre méthode permet d'obtenir des signaux ou des images interpolés de bonne qualité. En particulier, l'aspect visuel de régularité ou d'irrégularité est respecté après interpolation

Bayesian multifractal signal denoising

International audienceThis work presents an approach for signal/image denoising in a semi-parametric frame. Our model is a wavelet-based one, which essentially assumes a minimal local regularity. This assumption translates into constraints on the multifractal spectrum of the signals. Such constraints are in turn used in a Bayesian framework to estimate the wavelet coefficients of the original signal from the noisy ones. Our scheme is well adapted to the processing of irregular signals, such as (multi-)fractal ones, and is potentially useful for the processing of e.g. turbulence, bio-medical or seismic data

Local regularity-based interpolation

International audienceA ubiquitous problem in signal processing is to obtain data sampled with the best possible resolution. At the acquisition step, the resolution is limited by various factors such as the physical properties of the captors or the cost. It is therefore desirable to seek methods which would allow to increase the resolution after acquisition. This is useful for instance in medical imaging or target recognition. In some applications, one dispose of several low resolution overlapping signals [1]. In more general situations, a single signal is available for superresolution. Interpolation then requires that the available data be supplemented by some a priori information. Two types of methods have been explored: In the rst, "class-based" one, the signal is assumed to belong to some class, with conditions expressed mainly in the time or frequency domain [3, 5, 10]. This puts constraints on the interpolation, which is usually obtained as the minimum of a cost-function. The second type of approaches hypothesizes that the information needed to improve the resolution is local and is present in a class of similar signals [2, 4]. This type of approach could be called "contextual". Both "class-based" and "contextual" approaches use a "model" for interpolation: The "class-based model" is that the signal belongs to an abstract class characterized by a certain mathematical property. The "contextual model" is that the signal will behave locally under a change of resolution in way "similar" to other signals in a given set, for which a high resolution version is known. Both types of techniques have some drawbacks. Roughly speaking, class-based methods generally lead to overly smooth signals, while contextual-based ones, on the contrary, tend to generate spurious details

Signal and Image processing with FracLab

International audienceWe describe a software toolbox, called FracLab, for signal and image processing based on fractal and multifractal methods. We illustrate the use of FracLab on a numerical example, and give some new results for estimating fractal parameters in the course of the presentation

Memòria Digital de Catalunya

Tít. i menció de responsabilitat, que figuren al f. sign. a1, obtinguts de GWMarca de l'impr. al f. sign. y3Peu d'impr. obtingut del colofó (f. sign. y2v.)El f. sign. y4 en blancSignatures: a4, b-x8, y4Tipus gòtics, 2 columnes i registre al f. sign. a4Caplletres ornade

Fractal properties and characterization of road profiles

International audienceA major problem in road engineering is to understand the mechanisms of friction between rubber and the road. We study road profiles obtained using tactile and laser captors. these profiles belong to different category characterized by different friction coefficients. We find that all our profiles indeed display strong fractal behaviour in terms of both correlation exponents and regularization dimension over a large range of scales. However, neither of these fractal parameters seem to be related to friction. We then use a local fractal parameter, namely the pointwise Holder exponent. We show that this exponent does discriminate profiles which have different friction properties