Generalized Spatial Regression with Differential Regularization

We aim at analyzing geostatistical and areal data observed over irregularly shaped spatial domains and having a distribution within the exponential family. We propose a generalized additive model that allows to account for spatially-varying covariate information. The model is fitted by maximizing a penalized log-likelihood function, with a roughness penalty term that involves a differential quantity of the spatial field, computed over the domain of interest. Efficient estimation of the spatial field is achieved resorting to the finite element method, which provides a basis for piecewise polynomial surfaces. The proposed model is illustrated by an application to the study of criminality in the city of Portland, Oregon, USA

Cavity QED with hybrid nanocircuits: from atomic-like physics to condensed matter phenomena

Circuit QED techniques have been instrumental to manipulate and probe with exquisite sensitivity the quantum state of superconducting quantum bits coupled to microwave cavities. Recently, it has become possible to fabricate new devices where the superconducting quantum bits are replaced by hybrid mesoscopic circuits combining nanoconductors and metallic reservoirs. This mesoscopic QED provides a new experimental playground to study the light-matter interaction in electronic circuits. Here, we present the experimental state of the art of Mesoscopic QED and its theoretical description. A first class of experiments focuses on the artificial atom limit, where some quasiparticles are trapped in nanocircuit bound states. In this limit, the Circuit QED techniques can be used to manipulate and probe electronic degrees of freedom such as confined charges, spins, or Andreev pairs. A second class of experiments consists in using cavity photons to reveal the dynamics of electron tunneling between a nanoconductor and fermionic reservoirs. For instance, the Kondo effect, the charge relaxation caused by grounded metallic contacts, and the photo-emission caused by voltage-biased reservoirs have been studied. The tunnel coupling between nanoconductors and fermionic reservoirs also enable one to obtain split Cooper pairs, or Majorana bound states. Cavity photons represent a qualitatively new tool to study these exotic condensed matter states.Comment: 34 pages, 18 figures, 1 table, minor differences with the published version to appear in Journal of Physics: Condensed Matter as a topical revie

Numerical Contractor Renormalization Method for Quantum Spin Models

We demonstrate the utility of the numerical Contractor Renormalization (CORE) method for quantum spin systems by studying one and two dimensional model cases. Our approach consists of two steps: (i) building an effective Hamiltonian with longer ranged interactions using the CORE algorithm and (ii) solving this new model numerically on finite clusters by exact diagonalization. This approach, giving complementary information to analytical treatments of the CORE Hamiltonian, can be used as a semi-quantitative numerical method. For ladder type geometries, we explicitely check the accuracy of the effective models by increasing the range of the effective interactions. In two dimensions we consider the plaquette lattice and the kagome lattice as non-trivial test cases for the numerical CORE method. On the plaquette lattice we have an excellent description of the system in both the disordered and the ordered phases, thereby showing that the CORE method is able to resolve quantum phase transitions. On the kagome lattice we find that the previously proposed twofold degenerate S=1/2 basis can account for a large number of phenomena of the spin 1/2 kagome system. For spin 3/2 however this basis does not seem to be sufficient anymore. In general we are able to simulate system sizes which correspond to an 8x8 lattice for the plaquette lattice or a 48-site kagome lattice, which are beyond the possibilities of a standard exact diagonalization approach.Comment: 15 page

Frustration of the isotropic-columnar phase transition of colloidal hard platelets by a transient cubatic phase

Using simulations and theory, we show that the cubatic phase is metastable for three model hard platelets. The locally favored structures of perpendicular particle stacks in the fluid prevent the formation of the columnar phase through geometric frustration resulting in vitrification. Also, we find a direct link between structure and dynamic heterogeneities in the cooperative rotation of particle stacks, which is crucial for the devitrification process. Finally, we show that the life time of the glassy cubatic phase can be tuned by surprisingly small differences in particle shape.Comment: Submitted to Phys. Rev. Let

Expression of an Arabidopsis aspartic protease in Pelargonium : [Abstract L36]

Arabidopsis thaliana transgenic plants with constitutive over-expression of the aspartic protease gene At2g28010 (named CDS10) showed a bushy, multi-branching dwarf phenotype. In order to obtain compact plants of ornamental interest with an analogous phenotype in Pelargonium zonale, a tall cultivar (Boda Gitana Salmon) was transformed to over express the A. thaliana CDS 10 gene under the 35S promoter. Twenty seven transgenic lines were obtained with different levels of expression after gold particle bombardment and regeneration. Some of them showed indeed a bushy phenotype with a higher number of branches and a dwarf phenotype. However, an increase in the number of branches correlated with a decrease in the number of petals in the flowers. So the plants that were of interest from the compact habit point of view, had lost the double flower trait, and exhibited only 5 petals/flower which were also smaller than those from double flowers from the non transformed plants. Intermediate phenotypes with semidouble flowers and higher number of branches but without a compact phenotype were also observed. In order to determine if it was genotype related two other cultivars were transformed, Mirada Violet and Mirada Simple Pink double and single flower cultivars respectively. Transgenic plants showed indeed a higher number of branches and single flowers. Even if the busy phenotype was of interest in order to get a higher number of cuttings/plant and a compact phenotype, the pleiotropic effects of the over-expression of the A. thaliana CDS 10 gene on the flowers are too strong meaning it is only of interest in single flowered cultivars which are a small share of the market. (Résumé d'auteur

Variation in sport participation, fitness and motor coordination with socioeconomic status among Flemish children

Socioeconomic status (SES) is often indicated as a factor that influences physical activity and associated health outcomes. This study examined the relationship between SES and sport participation, morphology, fitness and motor coordination in a sample of 1955 Flemish children 6-11 years of age. Gender, age and SES-specific values for morphologic dimensions, amount and type of sport participation and fitness and motor coordination tests were compared. SES was positively and significantly associated with sport participation and sports club membership in both sexes. Although differences were not consistently significant, morphologic dimensions and tests of fitness and motor coordination showed a trend in favor of children from higher SES. The results suggest that public and local authorities should consider providing equal opportunities for children in all social strata and especially those in the lower SES to experience the beneficial effects of sport participation through which they can enhance levels of physical fitness and motor coordination

IGS: an IsoGeometric approach for Smoothing on surfaces

We propose an Isogeometric approach for smoothing on surfaces, namely estimating a function starting from noisy and discrete measurements. More precisely, we aim at estimating functions lying on a surface represented by NURBS, which are geometrical representations commonly used in industrial applications. The estimation is based on the minimization of a penalized least-square functional. The latter is equivalent to solve a 4th-order Partial Differential Equation (PDE). In this context, we use Isogeometric Analysis (IGA) for the numerical approximation of such surface PDE, leading to an IsoGeometric Smoothing (IGS) method for fitting data spatially distributed on a surface. Indeed, IGA facilitates encapsulating the exact geometrical representation of the surface in the analysis and also allows the use of at least globally $C^1-$continuous NURBS basis functions for which the 4th-order PDE can be solved using the standard Galerkin method. We show the performance of the proposed IGS method by means of numerical simulations and we apply it to the estimation of the pressure coefficient, and associated aerodynamic force on a winglet of the SOAR space shuttle