Child pedestrian anthropometry: evaluation of potential impact points during a crash

This paper highlights the potential impact points of a child pedestrian during a crash with the front end of a vehicle. Child anthropometry was defined for ages between 3 and 15 years. It was based on the measurement of seven different segment body heights (knee, femur, pelvis, shoulder, neck, chin, vertex) performed on about 2,000 French children. For each dimension, the 5^th, 50^th and 95^th percentile values were reported, and the corresponding linear regression lines were given. Then these heights were confronted with three different vehicle shapes, corresponding to a passenger car, a sport utility vehicle and a light truck, to identify impact points. In particular, we show that the thigh is directly hit by the bumper for children above 12 years of age, whereas the head principally impacts the hood. The influence of child anthropometry on the pedestrian trajectory and the comparison with test procedures in regulation are discussed.     

Investigations on high temperature polyimide potentialities for silicon carbide power device passivation

The operation of silicon carbide (SiC) power devices under severe conditions requires the development of thermally, electrically and chemically stable package. Passivation layer provides electrical insulation and environmental protection for the SiC die. As higher junction temperature and higher electric field can be reached within SiC component, consideration must be given to the thermal stability of the dielectric properties of the material in the die surrounding. Due to their supposed high operating temperature and dielectric strength, spin coated polyimide materials appear as a possible candidate for such passivation and insulation purposes. In this paper, we study the potentialities of a high temperature polyimide from HD Microsystems, for SiC power device passivation, at temperature up to 300 °C.     

Hall Effect in Quasi One-Dimensional Organic Conductors

We study the Hall effect in a system of weakly coupled Luttinger Liquid chains, using a Memory function approach to compute the Hall constant in the presence of umklapp scattering along the chains. In this approximation, the Hall constant decomposes into two terms: a high-frequency term and a Memory function term. For the case of zero umklapp scattering, where the Memory function vanishes, the Hall constant is simply the band value, in agreement with former results in a similar model with no dissipation along the chains. With umklapp scattering along the chains, we find a power-law temperature dependance of the Hall constant. We discuss the applications to quasi 1D organic conductors at high temperatures.     

Design and evaluation of a photoprotective compound able to release taurine under conditions of oxidative stress

Citation: IFSCC Magazine , 11 (2008) (2) 105–112
Abstract:  A novel photoprotective ingredient with anti-oxidant and electrophilic scavenging properties was designed. A structure–activity relationship study was conducted in order to optimize its bioavailability, specifically its ability to reach deep layers of the skin that may be affected by ultraviolet radiation-induced oxidative stress. A particular characteristic of this compound is its ability to release taurine upon reaction with some reactive oxygen species. In situ taurine formation may contribute to photoprotection. Preliminary in vitro experiments provide some evidence for effective protection against UVA-induced oxidative stress. Scavenging of the electrophilic species 4-hydroxynonenal, a highly cytotoxic end product of membrane lipid peroxidation, seems to be 2-oxo-1,3-thiazolidine major photoprotective mechanism.
Keywords:  antioxidant, electrophilic species scavenging, photoprotection, structure-activity relationship, taurine
Paper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands     

Comparative Genomics of Eight Fusarium graminearum Strains with Contrasting Aggressiveness Reveals an Expanded Open Pangenome and Extended Effector Content Signatures

Fusarium graminearum, the primary cause of Fusarium head blight (FHB) in small-grain cereals, demonstrates remarkably variable levels of aggressiveness in its host, producing different infection dynamics and contrasted symptom severity. While the secreted proteins, including effectors, are thought to be one of the essential components of aggressiveness, our knowledge of the intra-species genomic diversity of F. graminearum is still limited. In this work, we sequenced eight European F. graminearum strains of contrasting aggressiveness to characterize their respective genome structure, their gene content and to delineate their specificities. By combining the available sequences of 12 other F. graminearum strains, we outlined a reference pangenome that expands the repertoire of the known genes in the reference PH-1 genome by 32%, including nearly 21,000 non-redundant sequences and gathering a common base of 9250 conserved core-genes. More than 1000 genes with high non-synonymous mutation rates may be under diverse selection, especially regarding the trichothecene biosynthesis gene cluster. About 900 secreted protein clusters (SPCs) have been described. Mostly localized in the fast sub-genome of F. graminearum supposed to evolve rapidly to promote adaptation and rapid responses to the host’s infection, these SPCs gather a range of putative proteinaceous effectors systematically found in the core secretome, with the chloroplast and the plant nucleus as the main predicted targets in the host cell. This work describes new knowledge on the intra-species diversity in F. graminearum and emphasizes putative determinants of aggressiveness, providing a wealth of new candidate genes potentially involved in the Fusarium head blight disease.     

A model-based approach to the analysis of patterns of length of stay in institutional long-term care.

Understanding the pattern of length of stay in institutional long-term care has important practical implications in the management of long-term care. Furthermore, residents' attributes are believed to have significant effects on these patterns. In this paper, we present a model-based approach to extract, from a routinely gathered administrative social care dataset, high-level length-of-stay patterns of residents in long-term care. This approach extends previous work by the authors to incorporate residents' features. Two applications using data provided by a local authority in England are presented to demonstrate the potential use of this approach.     

Polynomial chaos expansion for sensitivity analysis

In this paper, the computation of Sobol's sensitivity indices from the polynomial chaos expansion of a model output involving uncertain inputs is investigated. It is shown that when the model output is smooth with regards to the inputs, a spectral convergence of the computed sensitivity indices is achieved. However, even for smooth outputs the method is limited to a moderate number of inputs, say 10-20, as it becomes computationally too demanding to reach the convergence domain. Alternative methods (such as sampling strategies) are then more attractive. The method is also challenged when the output is non-smooth even when the number of inputs is limited.     

Spectral schemes as ringed lattices

We give a point-free definition of a Grothendieck scheme whose underlying topological space is spectral. Affine schemes aside, the prime examples are the projective spectrum of a graded ring and the space of valuations corresponding to an abstract nonsingular curve. With the appropriate notion of a morphism between spectral schemes, elementary proofs of the universal properties become possible. “What would have happened if topologies without points had been discovered before topologies with points, or if Grothendieck had known the theory of distributive lattices?” Gian-Carlo Rota, Indiscrete Thoughts. Birkhäuser (1997), p. 220     

A new SURE approach to image denoising: interscale orthonormal wavelet thresholding.

This paper introduces a new approach to orthonormal wavelet image denoising. Instead of postulating a statistical model for the wavelet coefficients, we directly parametrize the denoising process as a sum of elementary nonlinear processes with unknown weights. We then minimize an estimate of the mean square error between the clean image and the denoised one. The key point is that we have at our disposal a very accurate, statistically unbiased, MSE estimate--Stein's unbiased risk estimate--that depends on the noisy image alone, not on the clean one. Like the MSE, this estimate is quadratic in the unknown weights, and its minimization amounts to solving a linear system of equations. The existence of this a priori estimate makes it unnecessary to devise a specific statistical model for the wavelet coefficients. Instead, and contrary to the custom in the literature, these coefficients are not considered random anymore. We describe an interscale orthonormal wavelet thresholding algorithm based on this new approach and show its near-optimal performance--both regarding quality and CPU requirement--by comparing it with the results of three state-of-the-art nonredundant denoising algorithms on a large set of test images. An interesting fallout of this study is the development of a new, group-delay-based, parent-child prediction in a wavelet dyadic tree.