Birman, Ko & Lee have introduced a new monoid Bn—with an explicit presentation— whose group of fractions is the n-strand braid group Bn. Building on a new approach by Digne, Michel and himself, Bessis has defined a dual braid monoid for every finite Coxeter type Artin-Tits group extending the type A case. Here, we give an explicit presentation for this dual braid monoid in the case of types B a...

For a large class of second order Lagrangian dynamics, one may reformulate the problem of finding periodic solutions as a problem in solving second-order recurrence relations satisfying a twist condition. We project periodic solutions of such discretized Lagrangian systems onto the space of closed braids and apply topological techniques. Under this reformulation, one obtains a gradient flow on ...

Nous appliquons le concept de séquences tressage aux polynômes skein et Conway, mais aussi à quelques invariants géométriques des entrelacs positifs. On donne estimations pour l’indice tresses legendriens, en utilisant degré propriétés croissance coefficients du polynôme Conway. énumérons asymptotiquement une constante près les alternants (et autres) genre donné par leur indice tresses.

The elasticity and flexibility of virgin and polymer-treated hair fiber assemblies were investigated by employing straight hair tresses or hair shaped into omega loops. Polymer treatment was accomplished by saturating fibers with polymeric solutions, resulting in a deposition of 10-90 mg of polymer per gram of hair. The mechanical testing procedure consisted of subjecting omega-loop-shaped hair...

Hair luster is one of the most important parameters of visual appearance perceived by consumers. Current luster formulae (TRI, Reich-Robbins, ...) are optimized for goniophotometric measurements. They are based on a mathematical decomposition of reflected light into specular and diffused light and the meaurement of the shine peak width on the fitted angular distributions. In this expose, we are...

La granulométrie de surface des lits fluviaux est un indicateur première importance pour l’évaluation conditions physiques qui contrôlent la qualité habitats aquatiques. Dans le cadre du protocole caractérisation hydromorphologique cours d’eau (CarHyCE) établi par l’Office français biodiversité (OFB), obtenue à partir d’un prélèvement au sol (de type Wolman) sur radier jugé représentatif, et d’...