Link and knot invariants from non-abelian Yang-Baxter 2-cocycles

We define a knot/link invariant using set theoretical solutions $(X,\sigma)$ of the Yang-Baxter equation and non commutative 2-cocycles. We also define, for a given $(X,\sigma)$, a universal group Unc(X) governing all 2-cocycles in $X$, and we exhibit examples of computations.Comment: 26 page

La maitrise d'oeuvre d’execution et la direction du projet d’extension de l’hôtel Shangri-La Paris

Ce rapport a pour intérêt d’expliquer et refléter le déroulement de la mission du stage abordé pendant les 6 mois dans l’entreprise Mercure Engineering & Consulting. Cette mission commence dans les bureaux de Mercure dédiés au projet de SLPR installés au pied du chantier au numéro 12 de la rue Fresnel. Le projet consiste en l’agrandissement de l’emblématique Hôtel Shangri-La Paris dans le 16ème arrondissement, situé dans le quartier privilégié du Trocadéro, avec vues spectaculaires sur la Tour Eiffel. L’hôtel Shangri-La Paris a eu l’opportunité d’agrandir et d’améliorer ses installations en achetant le bâtiment voisin numéro 8 de l’Avenue Iéna, mais aussi celui au numéro 12 de la rue Fresnel. Le premier situé dans la continuité de l’entrée principale de l’hôtel, il présente des caractéristiques similaires à l’hôtel actuel avec une façade digne du style parisien du début du siècle dernier. L’actuel palace Shangri-La au 10 avenue d’Iéna, qui avait appartenu jusqu’en 1896 au petit-neveu de Napoléon, le prince Roland Bonaparte, a été mis en fonctionnement en décembre 2010, après la restructuration de ce bâtiment historique par Affine Design-Richard Martinet, comme architecte-MOE et par Pierre-Yves Rochon comme décorateur. Par la suite l’hôtel a acheté l’immeuble privé voisin pour faire un agrandissement de ses installations. En 2011 les travaux d’extension de l’hôtel ont été démarrés sur site et Mercure s’incorpore en mars 2011 en tant que Maitre d’oeuvre d’exécution (MOE EXE). D’autres intervenants comme Affine Design, Pierre Yves Rochon, Gardiner&Theobald et Igrec engineering, feront partie de l’équipe de Maitrise d’oeuvre (MOE) et Lainé Delau (Groupe Vinci Constructions) en tant qu’entreprise générale. Dans la mission de Mercure, ma responsabilité a été d’assister la MOE EXE sur la direction du projet SLPR.Outgoin

VR Data visualization experience

During these recent years we have seen a massive increase in the use of Virtual Reality technologies and its multiple uses in different fields, from video games to medicine, engineering or art. In this project we will create a virtual reality project focused on the data visualization field. We will look at how to adapt data from a database into a data visualization experience that’s adapted to virtual reality and where the users will be able to immerse themselves and have a different and more interactive approach to data and data visualization. Throughout this project we will go through the whole development of the project from the conceptualization and design of it to the coding and implementation of all the features that the experience will have. We will also be able to see how data visualization technologies can be implemented into virtual reality and we will go through how the current state of the art is to this day

Microchimerism in Graves’ Disease

Microchimerism is the presence of cells from one individual in another genetically distinct individual. Pregnancy is the main cause of natural microchimerism through transplacental bidirectional cell trafficking between mother and fetus. The consequences of pregnancy-related microchimerism are under active investigation. However, many authors have suggested a close relationship linking fetal microchimerism and the development of autoimmune diseases. It has been more than ten years now since the demonstration of the presence of a significant high number of fetal microchimeric cells residing in thyroid glands from operated patients with Graves' disease. This intrathyroidal fetal microchimerism is an attractive candidate mechanism for the modulation of Graves' disease in pregnancy and the postpartum period

Tools for creating LaTeX-integrated graphics and animations under GNU/Linux

This paper describes how to easily create graphics and animations that can be included in LATEX documents. This article discusses three kinds of figures: plots, schematics, and pictures. The tools presented here can quickly generate plots, and are based on simple gnuplot and bash scripts that display the final result on the screen. Ipe is an excellent program to deal with complex figures and schematics, and the animate package is used to make a series of figures change over time to simulate a movie. All the programs used in this article are free software.Peer ReviewedPostprint (published version

Effects of gravity level on bubble formation and rise in low-viscosity liquids

We present an experimental analysis of the effects of gravity level on the formation and rise dynamics of bubbles. Experiments were carried out with millimeter-diameter bubbles in the hypergravity environment provided by the large-diameter centrifuge of the European Space Agency. Bubble detachment from a nozzle is determined by buoyancy and surface tension forces regardless of the gravity level. Immediately after detachment, bubble trajectory is deviated by the Coriolis force. Subsequent bubble rise is dominated by inertial forces and follows a zig-zag trajectory with amplitude and frequency dependent on the gravity level. Vorticity production is enhanced as gravity increases, which destabilizes the flow and therefore the bubble path.Peer ReviewedPostprint (published version

Effects of gravity level on bubble detachment, rise, and bouncing with a free surface

Bubble detachment, rise, and bouncing upon impact with a free surface is studied experimentally in variable gravity conditions. Previous investigations focused on the effects of fluid properties such as viscosity or surface tension on the rise and bouncing dynamics. Gravity force is a crucial factor in the detachment, rise and bouncing processes. However, the effect of different gravity levels has never been studied experimentally. In this paper we analyze the role of gravity in the detachment, rise velocity and bouncing motion of millimetric bubbles colliding with a free surface. Single air bubbles in ethanol are detached from a nozzle by the buoyancy force. After reaching a terminal velocity, the rising bubble interacts with the free surface in a bouncing process prior to coalescence. The equivalent bubble diameter at detachment decreases as the gravity level increases, in agreement with the theoretical prediction. An expression for the terminal velocity as a function of gravity is proposed. The terminal velocity is found to increase with the gravity level, although bubbles are smaller at higher values of gravity. The bouncing process has been modelled by a damped oscillator, in which the free surface acts as an elastic membrane. An expression for the frequency of bouncing as a function of gravity has been obtained, showing a good agreement with the experimental results. The motion of the bubble during the bouncing process can be approximated by an underdamped oscillator even if viscosity is negligible. Therefore, viscosity is not the main responsible for damping, which is probably due to energy transfer from the bubble to the fluid in the form of vortex and surface waves generation.Peer ReviewedPostprint (author's final draft

On ground study of bubble jets collision

Collisions of bubble jets have been experimentally studied in a normal gravity environment. Jets are introduced into a cavity full of liquid by means of a microbubble injector [1]. The experimental set-up, designed for a future use in low gravity conditions, allows the control of the impact angle between jets [2], bubble size and velocity. Individual bubble properties and the whole jet structure are analyzed from the images recorded. We present results on the role played by the impact angle and the distance between injectors on the structure of the final jet. A systematic study for different gas and liquid flow rates has been carried out in order to compare the results obtained in normal gravity with those to be obtained in a future campaign at INTA drop tower

Low Weber number jet collision regimes in microgravity

The outcome of the collision between two liquid jets depends on the liquid properties, jet velocity, and impact angle. So far studies on liquid jet impingement have been carried out in normal gravity conditions. In microgravity, jets are not accelerated and can show a different behavior than on ground. We perform an experimental analysis of the injection of liquid jets in microgravity, focusing in the jet impingement at different velocities and impact angles at low Weber numbers. Several regimes are obtained, some of which are not observable on ground. Other regimes take place at different parameter ranges than in normal gravity. A map of the observed regimes is proposed in terms of the Weber number and the impact angle.Peer ReviewedPostprint (author's final draft

Bouncing of bubbles impacting at a free surface

Peer ReviewedPostprint (published version