Narcolepsy-Cataplexy Today

peer reviewedDiagnostic criteria and pathophysiology of narcolepsy- cataplexy have evolved considerably over the last 10 years. The main cause, already mentioned in a previous paper, in the Revue Médicale de Liège, in 2002, is based, in human beings, on a destruction of specific cells located in the lateral and posterior part of the hypothalamus (the perifornical nuclei, containing some 70,000 neurons), producing peptides which stimulate the central nervous system; they are called hypocretins or orexins. The role of autoimmunity in their disappearance becomes more evident. The treatment is simplified but remains symptomatic. It is mainly based on Sodium Oxybate or Gamma-Hydroxybutyrate, syrup, prescribed for the night. The authors report on their own experience in this regard and on future therapeutics more targeted towards the cause of the disease

Finite-temperature and finite-time scaling of the directed polymer free-energy with respect to its geometrical fluctuations

We study the fluctuations of the directed polymer in 1+1 dimensions in a Gaussian random environment with a finite correlation length {\xi} and at finite temperature. We address the correspondence between the geometrical transverse fluctuations of the directed polymer, described by its roughness, and the fluctuations of its free-energy, characterized by its two-point correlator. Analytical arguments are provided in favor of a generic scaling law between those quantities, at finite time, non-vanishing {\xi} and explicit temperature dependence. Numerical results are in good agreement both for simulations on the discrete directed polymer and on a continuous directed polymer (with short-range correlated disorder). Applications to recent experiments on liquid crystals are discussed

Improvement in Thixoforging of 7075 Aluminium Alloys at High Solid Fraction

peer reviewedThixoforging is a type of semi-solid metal processing at high solid fraction (0.5<1). 7075 aluminium alloys have been used as a feedstock for thixoforging in order to investigate thixoformability of a high performance aluminium alloy at high solid fraction. Higher solid fraction of 7075 alloy is less sensitive to temperature, avoids metal splash at high speed and allows laminar flow at high speed. Hot tool combined with lubricant tool coating are used to slow down the solidification rate of the high solid fraction metal by decreasing thermal exchanges with the tool. Improved thermal and forming parameters [1-2] will be applied to produce an automotive component by thixoforging and mechanical properties have been measured from tensile samples. High mechanical properties are obtained after T6 thermal treatment

Comparison of 10 efficient protocols for photodynamic therapy of actinic keratosis: How relevant are effective light dose and local damage in predicting the complete response rate at 3 months?

International audienc

Steel thixoforming, influence of forming parameters on the microstructure

Forming of parts in the semi-solid state is quite a complex process, especially for high melting point alloys such as steel. A reason for this complexity is the amount of parameters involved in the process. Among these we could quote liquid fraction, shear rate, shape factor, contiguity, tool temperature, agglomeration level, heating rate, protecting gas, temperature distribution, lubricant. Of course all of these parameters don’t have the same order of importance. In this paper we show the influence of a set of chosen parameters and we highlight their effects on the microstructure and so, on the deformation behavior. The studied parameters are the heating conditions, the tool temperature, the part temperature, the thermal exchanges between the part and the dies and the forming rate

Thixoforging of 7075 Aluminium Alloys at High Solid Fraction

peer reviewedThixoforging is a type of semi-solid metal processing at high solid fraction (0.5 < f(s) < 1), which involves the processing of alloys in the semi-solid state. 7075 alloy has been used as a feedstock for thixoforming in order to investigate thixoformability of a high performance aluminium alloy at high solid fraction. The microstructure in semi-solid state consists of fine spheroidal solid grains surrounded by liquid. Thixo behaviour allows laminar flow that avoids macro-porosity and other casting defects and gives better mechanical properties; so we can reduce the weight of functional parts. Higher solid fraction of 7075 alloy is less sensitive to temperature, avoids metal splash at high speed, allows laminar flow at high speed and gives a good smooth surface without stick-slip phenomenon. The process is quicker with less energy and so the production rate increases and the tool has longer life. However, high solid fraction promotes freezing flow because of faster solidification and the lack of liquid phase. This freezing flow creates solid/liquid segregation and increases the forming force

Stability of steel thixoforging process

peer reviewedWhereas thixoforming of aluminum and other low melting point alloys is now an industrial reality, thixoforming of high melting point alloys, as steel, is still at the research level. High temperature issues, die wearing and production rate are problems that must be solved and are more and more investigated. This work focus on the study of a thixoforming line stability in the aim of industrialization of the process. The line is fully automated in order to maximize the repeatability of the experiments. Studied parameters are the heating cycle, the slug temperature, the tool temperature and the forming speed. For each of them we will give an order of magnitude of the expected variations in a steady-state process as well as the effects of these variations on the process itself (forming load and parts quality). Three different tools, and so three slugs and parts geometries, have been used in the experiments and are presented. Some mathematical simulations have been realized on the finite elements code Forge2008© with a semi-solid constitutive law and are also compared to the experiments. So the capacity of the model to represent the process stability is discussed as well

THIXOFORMAGE DES METAUX: Mise en forme rapide de pièces fonctionelles “near-net-shape” à design complexe dignes du forgeage!

Présentation du laboratoire de thixofomage de métaux.THIXALU - THIXOFO

Conception d'outillage adapté au thixoforgeage d'alliages d'aluminium à haute fraction solide sensibles à la fissuration à chaud

peer reviewedThixoforging is a type of semi-solid metal processing at high solid fraction (0.7<fs<1), which involves the processing of alloys in the semi-solid state. Tooling has to be adapted to this particular process to benefit of shear thinning and thixotropic behaviour of such semisolid material. Tooling parameters, as the forming speed and tool temperature, have to be accurately controlled because of their influence on thermal exchanges between material flow and tool. These thermal exchanges influence the high-cracking tendency and the rheology of the semisolid material during forming which affect parts properties. This paper shows, thanks to extrusion tests, how thermal exchanges influence surface quality of thixoforged parts made in 7075 aluminium alloys at high solid fraction by modifying process parameters like forming speed, tool temperature and tool thermal protector. A direct application is the evaluation of surface quality of thixoforged thin wall parts made in 7075 aluminium alloys