On the construction of discrete approximations to linear differential expressions

Algorithm for generating discrete approximations in terms of ordinates for linear differential expression

Optical polarimetric monitoring of the type II-plateau SN 2005af

Aims. Core-collapse supernovae may show significant polarization that implies non-spherically symmetric explosions. We observed the type II-plateau SN 2005af using optical polarimetry in order to verify whether any asphericity is present in the supernova temporal evolution. Methods. We used the IAGPOL imaging polarimeter to obtain optical linear polarization measurements in R (five epochs) and V (one epoch) broadbands. Interstellar polarization was estimated from the field stars in the CCD frames. The optical polarimetric monitoring began around one month after the explosion and lasted ~30 days, between the plateau and the early nebular phase. Results. The weighted mean observed polarization in R band was [1.89 +/- 0.03]% at position angle (PA) 54 deg. After foreground subtraction, the level of the average intrinsic polarization for SN 2005af was ~0.5% with a slight enhancement during the plateau phase and a decline at early nebular phase. A rotation in PA on a time scale of days was also observed. The polarimetric evolution of SN 2005af in the observed epochs is consistent with an overall asphericity of ~20% and an inclination of ~30 deg. Evidence for a more complex, evolving asphericity, possibly involving clumps in the SN 2005af envelope, is found.Comment: 6 pages, 5 figures, to be published A&

Vanishing Integral Relations and Expectation Values for Bloch Functions in Finite Domains

Integral identities for particular Bloch functions in finite periodic systems are derived. All following statements are proven for a finite domain consisting of an integer number of unit cells. It is shown that matrix elements of particular Bloch functions with respect to periodic differential operators vanish identically. The real valuedness, the time-independence and a summation property of the expectation values of periodic differential operators applied to superpositions of specific Bloch functions are derived.Comment: 10 page

Respuestas fisiológicas y moleculares al déficit hídrico en trigo (Triticum aestivum L.)

Physiological and molecular responses of five wheat genotypes: one Canadian cultivar, with low temperature tolerance, and 4 experimental lines, which demonstrated in the field high yield under drought stress were studied under water stress. We determined leaf relative water content and gene expression of rob 5 and dehydrins in response to low water availability. One genotype showed a higher RWC with less leaf Iresh weight and water soil content. There were not differences between genotypes in expression genes but, we found differences in gene expression between both tested genes. Rob 5 expressed in control as well as in stressed plants, while dehydrins only expressed in stressed plants and its expression increased as the water content of leaves decreased.Las respuestas fisiológicas y moleculares de cinco genotipos de trigo: un cultivar canadiense. tolerante a las bajas temperaturas y 4 líneas experimentales argentinas, que habían mostrado, un alto rendimiento a campo bajo condiciones de deficiencia hídrica, fueron estudiadas en condiciones de baja disponibilidad de agua. Se determine el contenido relativo de agua en las hojas y la expresión de 2 genes, rob 5 y dehidrinas, en respuesta a la baja disponibilidad de agua. Uno de los genotipos mostró mayor CRA con un menor contenido de agua en las hojas o en el suelo. No hubo diferencias genotípicas en la expresión de los genes sin embargo, fue diferente la expresión de estos, en respuesta al estr6s hídrico, dado que el gen Rob 5 se expresó tanto en las plantas control como en las estresadas, mientras que el de las dehydrinas solo se expresó en las plantas bajo estrés, y su expresión aumentó en función de la disminución del contenido relativo de agua de las hojas