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We consider the standing wavetrains that appear near threshold in a nearly conservative, parametrically excited, extended system that is invariant under space translations and reflection. Sufficiently close to threshold, the relevant equation is a Ginzburg-Landau equation whose cubic coefficient is extremely sensitive to wavenumber shifts, which can only be understood in the context of a more general quintic equation that also includes two cubic terms involving the spatial derivative. This latter equation is derived from the standard system of amplitude equations for counterpropagating waves, whose validity is well established today. The coefficients of the amplitude equation for standing waves are obtained for 1D Faraday waves in a deep container, to correct several gaps in former analyses in the literature. This application requires ...
The distribution of genetic variants of a group of low molecular weight, chloroform-methanol soluble proteins (CM proteins), among Moroccan and non-Moroccan accessions of Hordeum spontaneum and among selections from several Moroccan landraces of H. vulgare and cultivars of the same species with widespread European origin, suggests that domestication of barley might have taken place in Morocco. An agromorphological characterization of the H. spontaneum accessions further supports this hypothesis. The possible Moroccan origin of the French cultivar Hatif de Grignon and of several Spanish 6-rowed barleys is also presented.
El cambio del sistema económico y la reorganización de la producción que tuvo lugar en la segunda mitad del siglo XX generaron, en las ciudades y regiones industriales, una serie de transformaciones sociales y espaciales que resultan claves a la hora de entender su evolución. Regiones que durante más de cien años fueron verdaderos centros de producción y territorios de acogida para trabajadores de la industria han devenido, debido a diversos procesos de desindustrialización, en ciudades en crisis con graves problemas económicos, sociales y políticos que presentan un deterioro patente de sus estructuras. La Communauté Urbaine de Le Creusot - Montceau-les-mines se enfrentaba a unas cifras de paro crecientes, una población envejecida, un parque de viviendas en parte obsoleto y toda una serie de estructuras industriales abandonadas y en av...
El presente trabajo tiene la finalidad de explicar algunos rasgos fundamentales de la mineralización aurífera del complejo ofiolítico del noroeste de Holguín, Cuba, mediante comparación con yacimientos auríferos relacionados con zonas de cizalla en terrenos hercínicos del Macizo Ibérico (Urbano, R. 1998) (Castroviejo, R., 1998) (Cathelineau, M. et al.,1993) (Callan, N.J. y Spooner, E.T.C.1998), con los yacimientos filonianos del basamento hercínico y variscano de Francia (Bonnemaison, M. et al, 1987) (Bonnemaison, M. et al, 1991) y de cizalla del Escudo Canadiense (A.C. Colvine et al., 1984) (Callan, N.J.; Spooner, E.T.C. 1998). En este trabajo, se han tomado como referencia los aspectos relacionados con el tipo y grado de alteración, forma de ocurrencia, paragénesis minerales presentes, forma de acumulación de la sustancia mineral au...
In the nearly inviscid regime parametrically driven surface gravity-capillary waves couple to a streaming flow driven in oscillatory viscous boundary layers. In an elliptical container of small eccentricity this coupling can lead to relaxation oscillations.
Las nuevas tecnologías permiten incluir en las bases de datos BD las características espaciales de los datos, lo cual genera la necesidad de modelos que las soporten. Las bases de datos Multidimensionales BDM, son bases de datos que almacenan los datos de forma adecuada para analizarlos desde distintas perspectivas y con distintos niveles de detalle. La ausencia de estándares en modelos multidimensionales conceptuales para el diseño de estas BD, ha provocado que se utilicen extensiones de los modelos de las BD operacionales, los cuales no son adecuados ya que fueron concebidos para recoger una semántica distinta. Nuestra propuesta se basa, por un lado, en la necesidad de modelos conceptuales para recoger el paradigma multidimensional y por otro, en la necesidad de recoger las características espaciales de los datos, donde es de especia...
Thionins, which are high-sulphur polypeptides present in the endosperm of wheat and related species, have been found to prevent growth and to inhibit macromolecular synthesis in cultured mammalian cells. Baby hamster kidney (BHK) cells were markedly more sensitive to thionins than the other cell lines tested (monkey CV1, mouse L, human HeLa). A thionin concentration of 5 μ/ml (1 μM) completely blocked translation in BHK cells. It was later found that omission of both calcium and magnesium ions from the medium strongly enhanced the inhibitory effects of thionins (BHK cells, 80% inhibition, 0.5 μ/ml). Several lines of evidence indicate that thionins might act at the membrane level. Indeed, both the 86Rb+ content and the nucleotide pool of BHK cells were drastically decreased at thionin concentrations that inhibited translation. In additi...
The effect of vertical vibration on the long-wave instability of a Marangoni system is studied. The vibration augments the stabilizing effect of surface tension in bounded systems. In laterally unbounded systems nonlinear terms can stabilize non-flat states and prevent the appearance of dry spots. The effect of a slight inclination of the system is also considered.
Two homeologous proteins have been isolated from the endosperm of common wheat (genomes ABD). Synthesis of these two proteins is controlled by the homeologous chromosomes 7B and 7D respectively. However, Aegilops speltoides, the more generally accepted B genome donor, does not synthesize the 7B protein.
A two-dimensional thermal convection problem in a circular annulus subject to a constant inward radial gravity and heated from the inside is considered. A branch of spatio-temporal symmetric periodic orbits that are known only numerically shows a multi-critical codimension-two point with a triple +1-Floquet multiplier. The weakly nonlinear analysis of the dynamics near such point is performed by deriving a system of amplitude equations using a perturbation technique, which is an extension of the Lindstedt-Poincaré method, and solvability conditions. The results obtained using the amplitude equation are compared with those from the original system of partial differential equations showing a very good agreement.
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