La publication de ce volume a été rendue possible grâce à l'aide matérielle efficace de l'Université de Provence et de l'U.E.R. Arts Lettres Expression. La dactylographie a été assurée par ...Mademoiselle Christine de BROSSES (secrétariat de l'U.E.R. Arts Lettres Expression). Le volume a été imprimé et façonné par l'imprimerie de l'Université de Provence (centre d'Aix) sous la direction de Monsieur BEUQUE. La librairie Honoré CHAMPION a accepté d'en assurer la diffusion. Le bureau et le Conseil d'Administration du C.U.E.R. M.A. se font un agréable devoir d'exprimer à tous leur reconnaissance.
Neutron activation study of elementary composition was performed on edible sea urchins Paracentrotus lividus from the National Park of Port-Cros. The analysis allows the identification and ...quantification of 22 elements: antimony, arsenic, baryum, bromine, cerium, chromium, cesium, cobalt, gold, iron, lanthane, potassium, sodium, rubidium, samarium, scandium, selenium, silver, strontium, thorium, uranium and zinc. The concentration levels were higher in the soft organic parts (alimentary canals and gonads) for all the elements, except for strontium, which developed a strong affinity with calcareous hard parts (tests, spines, masticating apparatus). We also found high rates of baryum, arsenic, zinc, bromine and iron. The hypothesis on the origin of these elements is discussed. The data obtained on this referential zone will soon be used to appreciate the perturbation of the elementary composition of urchins by pollution in various parts of the French seashore.
L'image littéraire de la violence est fréquente dans les textes du Moyen Age, y compris dans ceux qui, a priori, ne semblent pas devoir lui accorder une place très importante. Il en est ainsi, par ...exemple, d'Aucassin et Nicolette, bien que Michel ZINK, dans son Introduction à la littérature française du Moyen Age, déclare que cette œuvre "raconte avec bonhomie sa petite histoire idyllique" et qu'Omer JODOGNE accuse son héros de n'être qu'"un pleurnichard sans dynamisme inventif".Pourtant, on ...
Si la littérature médiévale nous propose un grand nombre de portraits de marginaux volontaires : clercs vivant en dehors de la société normale, communautés, etc., elle nous présente aussi des ...individus qui, en raison d'une incapacité physique, psychologique ou autre, se trouvent, soit momentanément, soit en permanence, placés dans ce qui nous semble, à première vue, une véritable situation de ségrégation : la vie des lépreux du Tristan de Béroul ou celle d'Yvain "forsené" dans la forêt peuven...
An evaluation programme of Thomson CSF-TCS GaAs low noise and power MMIC technologies to 1 MeV equivalent neutron fluence levels, up to 1/spl times/10/sup 15/ n/cm/sup 2/, ionizing 1.17-1.33 MeV ...Co/sup 60/ dose levels in excess of 200 Mrad(GaAs) and dose rate levels reaching 1.89/spl times/10/sup 11/ rad(GaAs)/s is presented in terms of proper components and parameter choices, DC/RF electrical measurements and test methods under irradiation. Experimental results are explained together with drift analyses of electrical parameters that have determined threshold limits of component degradations. Modelling the effects of radiation on GaAs components relies on degradation analysis of active layer which appears to be the most sensitive factor. MMICs degradation under neutron fluence was simulated from irradiated FET data. Finally, based on sensitivity of technological parameters, rad-hard design including material, technology and MMIC design enhancement is discussed.
Posidonia oceanica meadows form the most representative community of the Mediterranean shores. However,
Posidonia oceanica meadows are fragile and in a bad way because of pollution and other ...nuisances. In several areas,
Posidonia meadows have been replaced with vast deserts of dead ‘mattes’ or sand and mud.
We owe to Cooper, now dead, the idea of using derelicts of
Posidonia to regenerate the meadows in the areas where the aggressive factors were eliminated. For that purpose he perfected a kind of concrete frame called ‘constraint’ which offers optimal conditions for these cuttings to take root.
So a study of scientific evaluation of Cooper's method has been undertaken in an experimental field of about
10 000 m
2
in the bay of Cannes. The ‘constraints’ were implanted over a period of
10 years, which gives particularly favourable conditions for studying their development. The work consisted of quantifying the vitality and the capacity of development of these cuttings with the help of classical tests such as the number of foliar bundles by surface unit, the biomass, the productivity, the number of running rhizomes and the surface of conquered ground. The results prove the effectiveness of the method which is now operational on a large scale.
We can now foresee and hope for a reconquest of the ruined bottoms, provided of course we first remove the causes of the disappearance of the natural meadows of
Posidonia oceanica.
The basic importance of polyamines, which are involved in the regulation of DNA, RNA and protein synthesis, are underlined in numerous works. Using HPLC analysis, we determined polyamine levels in ...several tissues of 10-day old adult crickets subjected to different hormonal conditions. Ovariectomy performed during the last larval instar suppressed haemolymph ecdysteroids and significantly increased the spermidine titres in nervous tissue whereas it decreased the overall polyamine levels in the fat body. Ecdysone injections into ovariectomized females reduced the spermidine content in nervous tissue and markedly increased the overall fat body polyamine levels, an effect which was mimicked by saline injections in this last tissue. As compared to control values, the activity of ornithine decarboxylase (ODC), the first key enzyme in polyamine biosynthesis was significantly reduced by ovariectomy either in nervous tissue or in fat body. In ovariectomized females, ecdysone injections significantly stimulated only the fat body ODC activity. The effects of polyamines on protein phosphorylation was examined. The phosphorylation of two proteins (207 and 128 kDa respectively) present in the fat body and the nervous tissue of control and ovariectomized females decreased in the presence of polyamines. The phosphorylation of a 53.5 kDa phosphoprotein only present in the nervous tissue differed according to the hormonal status of the female and was strongly enhanced by polyamines. Polyamines also stimulated the phosphorylation of a 37.5 kDa phosphoprotein present in both nervous tissue and fat body. In this last tissue, the phosphorylation of a 20 kDa phosphoprotein present in ovariectomized females was inhibited by the addition of polyamines. This work demonstrates an action of ecdysone on polyamine levels in nervous tissue and underlines the ability of polyamines to modulate the phosphorylation of specific phosphoproteins which are under hormonal control. These data emphasize the importance of polyamines in the regulation of cell functions.
A study was performed on females Acheta domesticus to examine the effects of various experimental conditions on the ovarian physiology. Using a radioimmunoassay to determine juvenile hormone (JH) ...titers as well as in vitro JH biosynthesis, we observed that retention of mature follicles in egg-retaining females, i.e., virgins or mated females not provided an egg-laying substrate, inhibits JH production and consequently oocyte development. Mating in intact as well as ovariectomized females does not affect corpora allata activity. It is only when mating is associated with egg laying that JH biosynthesis and hemolymph titers increased and oocyte development and fecundity are stimulated. Despite lower JH biosynthesis, ovariectomized females present enlarged corpora allata and the levels of JH observed in their hemolymph were intermediate between those of intact egg-laying and virgin females. In intact females, the hemolymph JH titers as well as the JH esterase activities were related to ovarian development. JH esterase activity was very high in ovariectomized animals. Several factors involved in ovarian development of A. domesticus are discussed.
