Results 1 - 10 of 139
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[en] A brief introduction to the dynamics of excitable systems is presented and the application of this class of systems to Neuro biology is emphasized by using the well known Fitz-Hugh-Nagumo model of spike generation. The introduction of noise terms in the equations is a necessary condition if we want to describe the spontaneous activity of neurons. Finally, the problem of noise-induced coherence is used as an example of application of stochastic excitable dynamical systems to the modelling of the firing behaviour of neurons. (Author) 7 refs
[en] These materials can undergo large deformations when subjected to external stresses when they are in the phase low temperature due to the super elasticity property. Super elasticity properties and memory effect form derived from the martensitic transformation, which thermoelastic transformation is involved in effort as well as temperature. The transformation autoacomodante called for a single crystal phase austenite gives rise to several crystals spontaneously martensite with their axes oriented in different directions to accommodate the deformation of the network. These crystals called variant or twins and their movement and change orientation gives rise to the super elasticity. (Author) 3 refs.
[en] This paper gives an overview of the various aspects associated with the development of coatings and thin films in all its aspects, from the preparation techniques to the technological applications. It addresses such important issues, such as the comparison of some techniques with others, or the choice of a deposition method to achieve certain characteristics in the deposited layer. (Author) 8 refs.
[en] The study of the surface of materials is supported by various experimental methods.This paper describes the techniques and methods within this field are used more widespread. Describe the basic processes, the experimental basis of each method, each provides information and some of its basic limitations. Finally, we note some new fields of interest, such as solid-liquid interfaces, biomaterials, modification surface of polymers, etc.. (Author) 26 refs.
[en] In this paper I present an example of the research that the Mineral Surface Group of the Munster University is conducting in the field of Crystal Growth. Atomic Force Microscopy (Am) in situ observations of different barite (BaSO4) faces growing from aqueous solutions, in combination with computer simulations of the surface attachment of growth units allows us to test crystal growth models. Our results demonstrate the strong structural control that a crystal can exert on its own growth, revealing also the limitation of the classical crystal growth theories (two dimensional nucleation and spiral growth models) in providing a complete explanation for the growth behaviour at a molecular scale. (Author) 6 refs
[en] Fullerenes and nanotubes represent a new allotropic form of the carbon element which have attracted the interest of scientists of different disciplines along the last recent years. A general overview on nanotubes is presented with special stress on the structure, properties and future applications of these fascinating new materials. (Author) 18 refs
[en] Different factors related to the formation of the Cerium magnetic ground state are analyzed from its electronic structure, following a decreasing scale of energy. The studied behaviours include from nonmagnetic states, like those with valence instability, to different magnetic phase diagrams. The competition between the Kondo effect, which screens the magnetic moments and the magnetic interactions, that tends to order them is also described. In the ordered phase boundary the phenomena related to the incipient magnetisms are analyzed and related to deviations from the Fermi liquid behaviour and divergences of the thermodynamic parameters when the temperature tend to zero. Some experimental techniques are described and the difference between thermodynamical and control parameters analyzed. Particular attention is paid to the effect of pressure and ligand substitution. (Author) 22 refs
[en] The ferroelectrics are materials of high permittivity dielectric is characterized by two states equilibrium with the same value of spontaneous polarization along the same direction (ferroelectric axis) but with a different sense of values polarization is due to a domain configuration or groups of dipoles with the same orientation its dipole moment, which is energetically favorable. (Author) 22 refs.
[en] The map has been Nuklidkarte Karlsruhe nuclei since 1958 the work of thousands of physicists and hundreds of thousands experimental results produced in institutes research worldwide. With excellence as rule, has become over the years a reference the field of nuclear information. (Author) 19 refs.