Exact oracle inequality for a sharp adaptive kernel density estimator

In one-dimensional density estimation on i.i.d. observations we suggest an adaptive cross-validation technique for the selection of a kernel estimator. This estimator is both asymptotic MISE-efficient with respect to the monotone oracle, and sharp minimax-adaptive over the whole scale of Sobolev spaces with smoothness index greater than 1/2. The proof of the central concentration inequality avoids "chaining" and relies on an additive decomposition of the empirical processes involved

Exact minimax risk for density estimators in non-integer Sobolev classes

The $L\_2$-minimax risk in Sobolev classes of densities with non-integer smoothness index is shown to have an analog form to that in integer Sobolev classes. To this end, the notion of Sobolev classes is generalized to fractional derivatives of order $\beta\in\mathbb R^+$. A minimax kernel density estimator for such a classes is found. Although there exists no corresponding proof in the literature so far, the result of this article was used implicitly in numerous papers. A certain necessity that this gap had to be filled, can thus not be denied

Analysis of luminosity distributions of strong lensing galaxies: subtraction of diffuse lensed signal

Strong gravitational lensing gives access to the total mass distribution of galaxies. It can unveil a great deal of information about the lenses dark matter content when combined with the study of the lenses light profile. However, gravitational lensing galaxies, by definition, appear surrounded by point-like and diffuse lensed signal that is irrelevant to the lens flux. Therefore, the observer is most often restricted to studying the innermost portions of the galaxy, where classical fitting methods show some instabilities. We aim at subtracting that lensed signal and at characterising some lenses light profile by computing their shape parameters. Our objective is to evaluate the total integrated flux in an aperture the size of the Einstein ring in order to obtain a robust estimate of the quantity of ordinary matter in each system. We are expanding the work we started in a previous paper that consisted in subtracting point-like lensed images and in independently measuring each shape parameter. We improve it by designing a subtraction of the diffuse lensed signal, based only on one simple hypothesis of symmetry. This extra step improves our study of the shape parameters and we refine it even more by upgrading our half-light radius measurement. We also calculate the impact of our specific image processing on the error bars. The diffuse lensed signal subtraction makes it possible to study a larger portion of relevant galactic flux, as the radius of the fitting region increases by on average 17\%. We retrieve new half-light radii values that are on average 11\% smaller than in our previous work, although the uncertainties overlap in most cases. This shows that not taking the diffuse lensed signal into account may lead to a significant overestimate of the half-light radius. We are also able to measure the flux within the Einstein radius and to compute secure error bars to all of our results

Self reliant groups from India to Scotland: lessons from south to north

There is a move towards partnership working across the global north and south but there remain questions about how to do it most effectively. This paper reports on the findings from a project that built a partnership between women in Scotland and India in order to transfer knowledge about Indian Self Help Groups. By creating peer to peer relationships that challenged traditional roles of 'teacher' and 'learner', the project was effective in transferring learning from south to north and generating meaningful outcomes for those involved. Despite the contextual differences, the successful transfer of key components of the model, savings, and loans, has led to a sense of empowerment in the Scottish women that is comparable to their Indian counterparts. As the project continues, it will be important that the dialogue between the partners continues, so there is ongoing learning as the Scottish groups expand and develop

An exploration of the ‘pushy parent’ label in educational discourse

This is the author accepted manuscript. The final version is available from Taylor and Francis via http://dx.doi.org/10.1080/01596306.2015.1064098This article explores the ideological function of the derogatory and polemical label of ‘pushy parent’, which, since the 1980s, has been used considerably in journalistic, popular, but also political and academic discourses in the UK and the USA. ‘Pushy parent’ is not a descriptive term, but a conceptually vague and culturally-specific label implying the existence of antagonistic agents intent on optimising their children’s educational attainment. The function of this label is to mask structural inequalities in educational opportunities and outcomes by making those inequalities imputable to individual practices. As such, the ‘pushy parent’ can be interpreted as what Roland Barthes calls an ‘inoculation’: a concept which allows for temporary discharges of indignation at a phenomenon evidencing social inequality, but which avoids a more systemic critique. The article first explores the distinction ‘pushy parenting’ sets up between ‘fake’ and ‘real’ intelligence, and ‘deserved’ and ‘undeserved’ educational achievement. However, as detailed in the second part of the essay, it is very difficult to draw clear conceptual boundaries between the behaviours and practices covered by ‘pushy parenting’, and those covered by the ‘ideal’ parenting practices of neoliberal educational policy. To conclude, the function of the ‘pushy parent’ label as inoculation is explored, as well as its implications for the cultural politics of education

Perfect simulation of a coupling achieving the dˉ\bar{d}-distance between ordered pairs of binary chains of infinite order

We explicitly construct a coupling attaining Ornstein's $\bar{d}$-distance between ordered pairs of binary chains of infinite order. Our main tool is a representation of the transition probabilities of the coupled bivariate chain of infinite order as a countable mixture of Markov transition probabilities of increasing order. Under suitable conditions on the loss of memory of the chains, this representation implies that the coupled chain can be represented as a concatenation of iid sequence of bivariate finite random strings of symbols. The perfect simulation algorithm is based on the fact that we can identify the first regeneration point to the left of the origin almost surely.Comment: Typos corrected. The final publication is available at http://www.springerlink.co

Paradoxical Interpretations of Urban Scaling Laws

Scaling laws are powerful summaries of the variations of urban attributes with city size. However, the validity of their universal meaning for cities is hampered by the observation that different scaling regimes can be encountered for the same territory, time and attribute, depending on the criteria used to delineate cities. The aim of this paper is to present new insights concerning this variation, coupled with a sensitivity analysis of urban scaling in France, for several socio-economic and infrastructural attributes from data collected exhaustively at the local level. The sensitivity analysis considers different aggregations of local units for which data are given by the Population Census. We produce a large variety of definitions of cities (approximatively 5000) by aggregating local Census units corresponding to the systematic combination of three definitional criteria: density, commuting flows and population cutoffs. We then measure the magnitude of scaling estimations and their sensitivity to city definitions for several urban indicators, showing for example that simple population cutoffs impact dramatically on the results obtained for a given system and attribute. Variations are interpreted with respect to the meaning of the attributes (socio-economic descriptors as well as infrastructure) and the urban definitions used (understood as the combination of the three criteria). Because of the Modifiable Areal Unit Problem and of the heterogeneous morphologies and social landscapes in the cities internal space, scaling estimations are subject to large variations, distorting many of the conclusions on which generative models are based. We conclude that examining scaling variations might be an opportunity to understand better the inner composition of cities with regard to their size, i.e. to link the scales of the city-system with the system of cities