Experimental and numerical signatures of dynamical crossover in orientationally disordered crystals

By means of NMR experiment and MD computer simulation we investigate the dynamical properties of a chloroadamantane orientationally disordered crystal. We find a plastic-plastic dynamical transition at T_x ~ 330 K in the pico-nanosecond regime. It is interpreted as the rotational analogue of the Goldstein crossing temperature between quasi-free diffusion and activated regime predicted in liquids. Below T_x, NMR experimental data are well described by a Frenkel model corresponding to a strongly anisotropic motion. At higher temperatures, a drastic deviation is observed toward quasi-isotropic rotational diffusion. Close to T_x, we observe that two-step relaxations emerge. An interpretation which is based on the present study of a specific heat anomaly detected by a recent calorimetric experiment is proposed.Comment: 4 pages, 4 figures; changed abstract and references; corrected figure

The Marine Products Export Development Authority

The Marine Products Export Development Authority (MPEDA), established by the Govt. of India as a statutory body in September 1972, is vested with the responsibility for the development of seafood industry in India with special reference to exports. The Authority functions under the administrative control of the Ministry of Commerce and has offices in all the major centres of seafood production and export in India, a Trade Promotion Office at New Delhi and overseas Trade Promotion Offices in Tokyo (Japan) and New York (USA)

Symposium on coastal aquaculture 12-18 January 1980

Aquaculture, though ancient in origin, has emerged as a recognised industry only during the last decade. While highly advanced and sophisticated technologies have been evolved for the capture of fishes, agriculture and livestock development, man has until recently neglected the farming of aquatic animals and plants. Several research and development organizations as well as universities in India and abroad are now engaged in intensive research on various aspects of coastal aquaculture. The Symposium will also deal with developmental aspects such as planning, organisation, socio-economics, legal, manpower requirements, training and industry relating to coastal aquaculture. The Symposium will be held for 7 days from 12th to 18th January, 1980

Souvenir: The Symposium on Mollusca Cochin; January 1968

The Marine Biological Association of Ind ia was organised on the 30th December '58 with its headquarters at Maodapam Camp and was formally inaugurated on 3rd January 1959 hy the Minister for Fisheries, Madras State

Onset of slow dynamics in difluorotetrachloroethane glassy crystal

Complementary Neutron Spin Echo and X-ray experiments and Molecular Dynamics simulations have been performed on difluorotetrachloroethane (CFCl2-CFCl2) glassy crystal. Static, single-molecule reorientational dynamics and collective dynamics properties are investigated. The orientational disorder is characterized at different temperatures and a change in nature of rotational dynamics is observed. We show that dynamics can be described by some scaling predictions of the Mode Coupling Theory (MCT) and a critical temperature $T_{c}$ is determined. Our results also confirm the strong analogy between molecular liquids and plastic crystals for which $\alpha$-relaxation times and non-ergodicity parameters are controlled by the non trivial static correlations as predicted by MCT

David R. Olson, L’Univers de l’écrit. Comment la culture écrite donne forme à la pensée

Encore un écrit sur l’écriture, encore un livre sur la mère de tous les livres, un de plus à ranger sur un rayon déjà bien garni ? Oui, mais le travail du Canadien David Olson se détache nettement du lot. Pour commencer par la plus flagrante de ses qualités, on y trouve une limpide et commode synthèse des recherches consacrées à la « raison graphique ». Proche de Jack Goody (à qui le livre est dédié), élève et collaborateur de Jérôme Bruner, l’auteur n’en est pas à son coup d’essai. Côté ency..