The Portraits of El Greco

This paper concentrates on the portraits of Dominicos Theotocopoulos, widely known as El Greco. An examination of his early studies in Crete, the process of icon making and his work in Italy provide a framework for the later paintings he produced in Spain. Initially, Byzantine icon-making and Western traditions of painting were combined in creating his first style of painting, which was the base of his art even during the last stages of his life when his paintings changed dramatically. European traditions of portraiture are, therefore, examined as quite important, since they created the guidelines for both patrons and artists in most artistic European centres. They are thus, analysed in order to establish the various influences El Greco drew from in order to create his own, distinctive style. El Greco's secular and religious portraits are looked upon in relation to the rest of his work as well as the creations of other Italian and Spanish artists of the time. His portrayal of saints in comparison to his portrayal of people he was acquainted with is also a considered factor. The discussion of all the paintings will lead to the legacy he left behind and the influence he had on artists of a later period such as Francis Bacon

Guindilia dissecta (Covas & Burkart) Hunz.

Luján, El SaltopublishedVersio

Digestibilidad y energía metabolizable en Amaranthus greggii S. Wats.

Amaranthus greggii S. Wats. es una especie de posible valor alimenticio, perenne, susceptible a heladas, cultivable bajo cubierta, a la que se le han estudiado algunos caracteres organolépticos, composición química y posibles aplicaciones hortícolas

Producción de forraje y semilla de tres especies de Bromus

The objectives of this study were to evaluate the forage yield, protein content and seed yield of pampean bromegrass, rescue gran, and intermediate bromegrass experimental Iines. The cultivar "Don Lorenzo INTA" of intermediate bromegrass was used as reference. Two randomized complete block designs with 4 replicates were done, one for forage yield and protein contentand the other for seed yield and 1000 seed weight. ANOVA and FLSO tests (p<0,05) were also performed. L1nesof the three species shown similar forage yield and protein content, thus all of them should be considered to be Improved through plant breeding. Intermediate bromegrass showed lower seed production than the other. This character is a disadvantage to get a success with natural reseeding. The cultivar "Don Lorenzo INTA" of Intermediate bromegrass showed Intermediate values in forage and seed yields.Los objetivos de este trabajo fueron evaluar producción forrajera, contenido de proteína, y producción de semilla de líneas experimentales de cebadillas pampeana, criolla e intermedia. Se utilizó como referencia al cultivar Don Lorenzo INTA de cebadilla Intermedia. Se realizaron dos ensayos según un diseño en bloques completos aleatorizados con cuatro repeticiones. En uno se evaluó producción de materia seca y contenido de proteína, y en la otra producción de semilla y peso de mil semillas. Se realizó ANOVA y OMS (p<0,05). Líneas de las tres especies presentaron similares producciones de forraje y contenido de proteína, por lo que todas deben ser consideradas al desarrollar planes de mejoramiento. La cebadilla Intermedia presentó menor producción de semilla que las restantes, lo que podría constituir una desventaja desde el punto de vista de la resiembra espontánea. El cultivar Don Lorenzo INTA presentó valores de producción intermedios tanto de forraje como de semilla

Can catastrophic quenching be alleviated by separating shear and alpha effect?

The small-scale magnetic helicity produced as a by-product of the large-scale dynamo is believed to play a major role in dynamo saturation. In a mean-field model the generation of small-scale magnetic helicity can be modelled by using the dynamical quenching formalism. Catastrophic quenching refers to a decrease of the saturation field strength with increasing Reynolds number. It has been suggested that catastrophic quenching only affects the region of non-zero helical turbulence (i.e. where the kinematic alpha operates) and that it is possible to alleviate catastrophic quenching by separating the region of strong shear from the alpha layer. We perform a systematic study of a simple axisymmetric two-layer alpha-omega dynamo in a spherical shell for Reynolds numbers in the range 1 < Rm < 10^5. In the framework of dynamical quenching we show that this may not be the case, suggesting that magnetic helicity fluxes would be necessary.Comment: 8 pages, 5 figures (Accepted in Geophysical and Astrophysical Fluid Dynamics

Magnetic field generation in fully convective rotating spheres

Magnetohydrodynamic simulations of fully convective, rotating spheres with volume heating near the center and cooling at the surface are presented. The dynamo-generated magnetic field saturates at equipartition field strength near the surface. In the interior, the field is dominated by small-scale structures, but outside the sphere by the global scale. Azimuthal averages of the field reveal a large-scale field of smaller amplitude also inside the star. The internal angular velocity shows some tendency to be constant along cylinders and is ``anti-solar'' (fastest at the poles and slowest at the equator).Comment: 12 pages, 11 figures, 2 tables, to appear in the 10 Feb issue of Ap

Transverse instability for non-normal parameters

We consider the behaviour of attractors near invariant subspaces on varying a parameter that does not preserve the dynamics in the invariant subspace but is otherwise generic, in a smooth dynamical system. We refer to such a parameter as ``non-normal''. If there is chaos in the invariant subspace that is not structurally stable, this has the effect of ``blurring out'' blowout bifurcations over a range of parameter values that we show can have positive measure in parameter space. Associated with such blowout bifurcations are bifurcations to attractors displaying a new type of intermittency that is phenomenologically similar to on-off intermittency, but where the intersection of the attractor by the invariant subspace is larger than a minimal attractor. The presence of distinct repelling and attracting invariant sets leads us to refer to this as ``in-out'' intermittency. Such behaviour cannot appear in systems where the transverse dynamics is a skew product over the system on the invariant subspace. We characterise in-out intermittency in terms of its structure in phase space and in terms of invariants of the dynamics obtained from a Markov model of the attractor. This model predicts a scaling of the length of laminar phases that is similar to that for on-off intermittency but which has some differences.Comment: 15 figures, submitted to Nonlinearity, the full paper available at http://www.maths.qmw.ac.uk/~eo

Magnetic helicity fluxes in interface and flux transport dynamos

Dynamos in the Sun and other bodies tend to produce magnetic fields that possess magnetic helicity of opposite sign at large and small scales, respectively. The build-up of magnetic helicity at small scales provides an important saturation mechanism. In order to understand the nature of the solar dynamo we need to understand the details of the saturation mechanism in spherical geometry. In particular, we want to understand the effects of magnetic helicity fluxes from turbulence and meridional circulation. We consider a model with just radial shear confined to a thin layer (tachocline) at the bottom of the convection zone. The kinetic alpha owing to helical turbulence is assumed to be localized in a region above the convection zone. The dynamical quenching formalism is used to describe the build-up of mean magnetic helicity in the model, which results in a magnetic alpha effect that feeds back on the kinetic alpha effect. In some cases we compare with results obtained using a simple algebraic alpha quenching formula. In agreement with earlier findings, the magnetic alpha effect in the dynamical alpha quenching formalism has the opposite sign compared with the kinetic alpha effect and leads to a catastrophic decrease of the saturation field strength with increasing magnetic Reynolds numbers. However, at high latitudes this quenching effect can lead to secondary dynamo waves that propagate poleward due to the opposite sign of alpha. Magnetic helicity fluxes both from turbulent mixing and from meridional circulation alleviate catastrophic quenching.Comment: 9 pages, 14 figures, submitted to A &

Resistencia al carbón de la panoja en líneas de cebadillas (Bromus spp.)

The main purpose of this study was to identify resistance of experimental lines of Bromus catharticus, B. parodii y B. brevis to Ustilago bullata, an important head smut pathogen of brome grass. Seeds of 100 experimental lines were inoculated with a uniform mass of ustilospores obtained from each species and seeded in field plots in 1992. At maturity the number of smutted panicles were counted. Data were compared by using "1.2 test of homogeneity. B. brevis and B. parodii experimental lines varied in their reactions to U. bullata. AII B. catharticus plants were susceptible to the pathogen. Differences in susceptibility were found between geographic sources of B. brevis and B. parodii genotypes.El objetivo de este trabajo fue determinar el comportamiento de lineas de Bromus catharticus, B. parodii y B. brevis al ataque del hongo Ustilago bullata y, eventualmente seleccionar las resistentes a la enfermedad. Se sembraron 100 líneas inoculadas con ustilosporas del carbón cosechadas sobre la misma especie. Se efectuó el recuento de panojas atacadas y no atacadas. Los datos se analizaron por prueba "1.2 de homogeneidad. Todas las líneas de B. catharticus fueron susceptibles al hongo. Se encontraron distintos grados de ataque al carbón de la panoja en B. brevis y B. parodii. Se hallaron diferencias de resistencia de acuerdo al origen geográfico en las líneas de B. brevis y B. parodii