SNUS-2.5, a Multimoment Analysis of Road Demand, Accidents and their Severity in Germany, 1968 – 1989

The present article presents an improved and refined version of the SNUS-1 model (GAUDRY and BLUM 1993) documented only in French. The greatest difficulty faced in the development of the model did not have to do with structure – the multilevel structure is straightforward – but with the specification of the employment activity variable, due to the specifics of the German economy,and with the proper formulation of the role of vehicle stocks in the road demand models. Moreover,we consider the following aspects to be special in the context of an analysis of Germany: • there exist no general speed limits on motorways, i.e. about 70% allow unlimited speed today,and in the Sixties, when our analysis starts, this share was even higher; • the country is large compared with other regions were the DRAG-methodology is employed, and it possesses high car ownership levels and an important car industry that sees the German infrastructure as an appropriate testing ground; • Germany is poly-central, its infrastructure resembles a grid, whereas France’s is almost a huband-spoke system, as compared for instance to Norway’s line; • unification is not yet included because of lagging data availability and, thus, problems to compensate for the structural break in data series.Classification-JEL:

Improved Complexity Bounds for Counting Points on Hyperelliptic Curves

We present a probabilistic Las Vegas algorithm for computing the local zeta function of a hyperelliptic curve of genus $g$ defined over $\mathbb{F}_q$. It is based on the approaches by Schoof and Pila combined with a modeling of the $\ell$-torsion by structured polynomial systems. Our main result improves on previously known complexity bounds by showing that there exists a constant $c>0$ such that, for any fixed $g$, this algorithm has expected time and space complexity $O((\log q)^{cg})$ as $q$ grows and the characteristic is large enough.Comment: To appear in Foundations of Computational Mathematic

Fast genus 2 arithmetic based on Theta functions

descriptionInternational audienceIn 1986, D. V. Chudnovsky and G. V. Chudnovsky proposed to use formulae coming from Theta functions for the arithmetic in Jacobians of genus 2 curves. We follow this idea and derive fast formulae for the scalar multiplication in the Kummer surface associated to a genus 2 curve, using a Montgomery ladder. Our formulae can be used to design very efficient genus 2 cryptosystems that should be faster than elliptic curve cryptosystems in some hardware configurations

Evidence for an additive inhibitory component of contrast adaptation

The latency of visual responses generally decreases as contrast increases. Recording in the lateral geniculate nucleus (LGN), we find that response latency increases with increasing contrast in ON cells for some visual stimuli. We propose that this surprising latency trend can be explained if ON cells rest further from threshold at higher contrasts. Indeed, while contrast changes caused a combination of multiplicative gain change and additive shift in LGN cells, the additive shift predominated in ON cells. Modeling results supported this theory: the ON cell latency trend was found when the distance-to-threshold shifted with contrast, but not when distance-to-threshold was fixed across contrasts. In the model, latency also increases as surround-to-center ratios increase, which has been shown to occur at higher contrasts. We propose that higher-contrast full-field stimuli can evoke more surround inhibition, shifting the potential further from spiking threshold and thereby increasing response latency

Un aperçu de DRAG, un modèle de sécurité routière compréhensif

We provide a primarily qualitative summary of the DRAG model of the Demand for Road use, Accidents and their Gravity. We show the comprehensive nature of the model in terms of structure, categories of factors taken into account and parameter estimation technique used. We note in particular how the very structure of the DRAG model makes it possible to decompose the impact of each explanatory factor on exposure risk, as well as on accident frequency and severity—thus making it possible to detect the presence of substitution among the different dimensions of driving risk. We give an idea of the application and results obtained for the Province of Quebec and mention the emergence of a European network of DRAG-inspired modeling efforts. Nous faisons un résumé surtout qualitatif de DRAG, un modèle explicatif de la Demande Routière, des Accidents et de leur Gravité. Nous montrons le caractère compréhensif du modèle, en ce qui a trait à sa structure, aux catégories de facteurs explicatifs prises en compte et aux méthodes d’estimation des paramètres utilisées. Nous soulignons en particulier comment la structure même de DRAG permet de décomposer la contribution de chaque facteur explicatif de l’insécurité routière entre des effets sur l’exposition au risque, sur la fréquence et sur la gravité des accidents — et comment on peut ainsi étudier la présence de substitution entre les diverses dimensions du risque de conduite. Nous donnons une idée de l’application et des résultats obtenus pour le Québec et faisons mention de travaux européens en cours inscrits dans la foulée de DRAG.

Artificial Tongue-Placed Tactile Biofeedback for perceptual supplementation: application to human disability and biomedical engineering

The present paper aims at introducing the innovative technologies, based on the concept of "sensory substitution" or "perceptual supplementation", we are developing in the fields of human disability and biomedical engineering. Precisely, our goal is to design, develop and validate practical assistive biomedical and/technical devices and/or rehabilitating procedures for persons with disabilities, using artificial tongue-placed tactile biofeedback systems. Proposed applications are dealing with: (1) pressure sores prevention in case of spinal cord injuries (persons with paraplegia, or tetraplegia); (2) ankle proprioceptive acuity improvement for driving assistance in older and/or disabled adults; and (3) balance control improvement to prevent fall in older and/or disabled adults. This paper presents results of three feasibility studies performed on young healthy adults

Cell surface localization of tissue transglutaminase is dependent on a fibronectin-binding site in its N-terminal beta-sandwich domain

Increasing evidence indicates that tissue transglutaminase (tTG) plays a role in the assembly and remodeling of extracellular matrices and promotes cell adhesion. Using an inducible system we have previously shown that tTG associates with the extracellular matrix deposited by stably transfected 3T3 fibroblasts overexpressing the enzyme. We now show by confocal microscopy that tTG colocalizes with pericellular fibronectin in these cells, and by immunogold electron microscopy that the two proteins are found in clusters at the cell surface. Expression vectors encoding the full-length tTG or a N-terminal truncated tTG lacking the proposed fibronectin-binding site (fused to the bacterial reporter enzyme β-galactosidase) were generated to characterize the role of fibronectin in sequestration of tTG in the pericellular matrix. Enzyme-linked immunosorbent assay style procedures using extracts of transiently transfected COS-7 cells and immobilized fibronectin showed that the truncation abolished fibronectin binding. Similarly, the association of tTG with the pericellular matrix of cells in suspension or with the extracellular matrix deposited by cell monolayers was prevented by the truncation. These results demonstrate that tTG binds to the pericellular fibronectin coat of cells via its N-terminal β-sandwich domain and that this interaction is crucial for cell surface association of tTG

Construction of secure random curves of genus 2 over prime fields

International audienceFor counting points of Jacobians of genus 2 curves defined over large prime fields, the best known method is a variant of Schoof's algorithm. We present several improvements on the algorithms described by Gaudry and Harley in 2000. In particular we rebuild the symmetry that had been broken by the use of Cantor's division polynomials and design a faster division by 2 and a division by 3. Combined with the algorithm by Matsuo, Chao and Tsujii, our implementation can count the points on a Jacobian of size 164 bits within about one week on a PC