[en] The development of new techniques in the field of external radiotherapy opens new ways of gaining accuracy in dose distribution, in particular through the knowledge of individual lung motion. The numeric simulation NEMOSIS (Neural Network Motion Simulation System) we describe is based on artificial neural networks (ANN) and allows, in addition to determining motion in a personalized way, to reduce the necessary initial doses to determine it. In the first part, we will present current treatment options, lung motion as well as existing simulation or estimation methods. The second part describes the artificial neural network used and the steps for defining its parameters. An accurate evaluation of our approach was carried out on original patient data. The obtained results are compared with an existing motion estimated method. The extremely short computing time, in the range of milliseconds for the generation of one respiratory phase, would allow its use in clinical routine. Modifications to NEMOSIS in order to meet the requirements for its use in external radiotherapy are described, and a study of the motion of tumor outlines is carried out. This work lays the basis for lung motion simulation with ANNs and validates our approach. Its real time implementation coupled to its predication accuracy makes NEMOSIS promising tool for the simulation of motion synchronized with breathing. (author)

[en] The tests comprised tensile tests under constant load or up to the fracture point using cylindrical or flat, trapezoidal test pieces, tests in which disks were ruptured under gaseous pressure, and tenacity tests. The alloy was found to be sensitive to: (1) intrinsic brittleness (I.B.) due to dissolved residual hydrogen from the preparation stage. This manifested itself mainly by cracking at an elongation threshold of about 3 percent. (2) Cracking due to stress corrosion (S.C.C.) in the true sense, which is made possible under certain conditions by an imperfect passivation of the metal surface. The process is initiated either by the appearance of microcracks which appear at the surface, or by corrosion pits. (3) Generalized corrosion accelerated by the stress (S.A.C.), whose microscopic appearance is similar to that observed with corrosion under gaseous hydrogen. Below pH 2 there is no stress corrosion. Stress rupture tests in moist air at 80 and 100⁰C measure I.B. + S.C.C. under high stress, giving rise to short lifetimes. I.B. + S.C.C. + S.A.C., with S.A.C. predominant, occurs under lower stresses that give long lifetimes. Stress rupture tests measure at 20 and 60⁰C I.B. + S.C.C. with I.B. predominant. Under high stresses (short lifetimes) the magnitude of the S.C.C. component increases as the temperature increases. The most serious effects are those of S.A.C. at 80 and 100⁰C, and of I.B. at all temperatures. The way this alloy behaves can only be changed by an effective reduction in the quantity of residual hydrogen present, or by coatings that will in no case allow the ingress of hydrogen. 62 fig, 82 references, 15 tables

No abstract available

[en] Characterization of the intrinsic or provoked brittlenesses in a wide range of experimental conditions: temperature, deformation rate, slow fatigue, permeability to hydrogen, specific parameters (welding for ex.) The use is rapid and inexpensive. The breaking or cracking pressure of discs set in at their periphery is measured and the pressures obtained in conditions of embrittlement and in a reference environment are compared. The possibility of using or not using the material in the given conditions is then deduced as is the reproducibility of its response to these conditions

[en] A mechanical test for characterizing embrittlement of materials under stress and non-homogeneous deformation is described. In this test a disk, fixed at the periphery, is broken by an increasing gas pressure, pressures obtained are compared in standard conditions and in conditions producing brittleness. The ratio between these two pressures is a quantitative measurement of the damage. Fracture morphology gives indications on embrittlement

[en] This device enables the embrittlement of materials to be studied under a great variety of experimental conditions and hence determine their area of use. It consists in characterizing the breaking of metal discs under gas pressure depending on temperature, the kind of gas, pressure, number of thermal cycles, etc

[en] We describe a set up essentially aimed at the determination of very small hydrogen amounts in metals and specially uranium alloys. This set up designed and built up in our laboratory is characterized by its very high sensitivity due on one side to experimental precaution and on the other side to an original analytical procedure, which allows to take the samples surface contamination into account. This equipment comes out as a useful addition to the existing commercial devices, which are limited to a sensitivity of 0.1x10^-6 under the best circumstances

[en] A quick rough analysis of stellar activity can be accomplished by studying the interrelations of the various observables. Tight correlations between observables suggest general physical relation. The aim of this study is to observe with the IUE satellite a homogeneous sample of stars for which there are extensive coronal data. The X-ray studies of close binaries provided such a sample. Because of intrinsic stellar variability, this type of study is best carried out when all observables are measured simultaneously. So, correlation plots are constructed in which the normalized flux is plotted in a log-log plane against various canonical observables, viz. MgII for the chromosphere, CIV for the transition region, and X-rays for the corona. The author has examined the relations both for the binary sample as a whole, which includes active K and G subgiant RS CVn stars and G main sequence components, and for the K subgiants separately. (Auth.)

No abstract available

[en] The authors describe the method used for quantitative measurement of U, Th and Pb in a zircon concentrate. They go on to mention the various procedures they used to obtain high sensitivity, good reproducibility and high speed in the detection of these elements in trace amounts. The limitations, advantages and difficulties of X-fluorescence as applied to this particular case are discussed on the theoretical level, and then illustrated by practical examples. The Larsen method, applied systematically to all the massifs of the Alpine range, is put into practice on one of them. The following conclusions can be drawn from the results obtained: 1. A first orogenic cycle seems to go back to the Upper Precambrian. In fact, ages of more than 600 m. y. have been obtained; 2. The intrusive granites were laid down during the Hercynian orogenesis (pre-Stephanian phase). The dispersion of the results may be partly attributed to the effects of the Alpine orogenesis and of the late Hercynian phase; 3. The gneiss of sedimentary origin (paragneiss and endomigmatites) give ages of between 450 and 600 m. y. (Lower Palaeozoic). (author)