Pion-to-vacuum vector and axial vector amplitudes and weak decays of pions in a magnetic field

We propose a model-independent parametrization for the one-pion-to-vacuum matrix elements of the vector and axial vector hadronic currents in the presence of an external uniform magnetic field. It is shown that, in general, these hadronic matrix elements can be written in terms of several gauge covariant Lorentz structures and form factors. Within this framework we obtain a general expression for the weak decay $\pi^- \to l\,\bar\nu_l$ and discuss the corresponding limits of strong and weak external magnetic fields.Comment: 33 page

Electrically Mediated Delivery of Vector Plasmid DNA Elicits an Antitumor Effect

In vivo electroporation is an efficient means of increasing plasmid DNA delivery to normal tissues, such as skin and muscle, as well as directly to tumors. In the experiments described here, plasmid DNA was delivered by in vivo electroporation to B16 mouse melanomas using two very different pulsing protocols. Reporter expression increased 21- or 42-fold, respectively with electroporation over injection alone. The growth of experimental melanomas with an approximate diameter of 4 mm on the day of treatment was monitored after electroporation delivery of reporter plasmid DNA. Remarkably, short-term complete regressions using one of these pulsing protocols occurred in up to 100% of mice. These regressions continued long term in up to 83% of animals. 70% of these mice were resistant to challenge with B16 melanoma cells. Histological analysis revealed large numbers of apoptotic cells 24 h after treatment. This antitumor effect did not require therapeutic cDNA expression or eukaryotic sequences

Non-thermal photons and direct photodissociation of H2, HD and HeH+ in the chemistry of the primordial Universe

Non-thermal photons deriving from radiative transitions among the internal ladder of atoms and molecules are an important source of photons in addition to thermal and stellar sources in many astrophysical environments. In the present work the calculation of reaction rates for the direct photodissociation of some molecules relevant in early Universe chemistry is presented; in particular, the calculations include non-thermal photons deriving from the recombination of primordial hydrogen and helium atoms for the cases of H2, HD and HeH+. New effects on the fractional abundances of chemical species are investigated and the fits for the HeH+ photodissociation rates by thermal photons are provided.Comment: 6 pages, 4 figures, 1 table; accepted for publication on MNRA

Tendencias de los procesos de evaluación de la calidad de la educación superior en Europa.

Este artículo pretende dar cuenta de las principales tendencias acerca de los procesos de evaluación y acreditación de la calidad de los sistemas de educación superior europeos, a partir del denominado Proceso de Bologna. Concibiendo el tema de la calidad como un concepto clave en tanto se considera un bien público y como un factor determinante de la competitividad de un país, nos proponemos dar cuenta de las tendencias en este campo y plantear algunas conclusiones que contribuyan al análisis y el debate

The Stationary Phase Method for a Wave Packet in a Semiconductor Layered System. The applicability of the method

Using the formal analysis made by Bohm in his book, {\em "Quantum theory"}, Dover Publications Inc. New York (1979), to calculate approximately the phase time for a transmitted and the reflected wave packets through a potential barrier, we calculate the phase time for a semiconductor system formed by different mesoscopic layers. The transmitted and the reflected wave packets are analyzed and the applicability of this procedure, based on the stationary phase of a wave packet, is considered in different conditions. For the applicability of the stationary phase method an expression is obtained in the case of the transmitted wave depending only on the derivatives of the phase, up to third order. This condition indicates whether the parameters of the system allow to define the wave packet by its leading term. The case of a multiple barrier systems is shown as an illustration of the results. This formalism includes the use of the Transfer Matrix to describe the central stratum, whether it is formed by one layer (the single barrier case), or two barriers and an inner well (the DBRT system), but one can assume that this stratum can be comprise of any number or any kind of semiconductor layers.Comment: 15 pages, 4 figures although figure 4 has 5 graph

Validation of an automated spectrophotometric method to dose SO2 in vinegar

Sulfur dioxide and sulfites are considered allergens, and their levels in food are regulated by law. The method used to dose free and total sulfites in vinegar is the Ripper method which consists of a direct titration with iodine using starch as an indicator. The Ripper method involves long and elaborate processes, requires excellent operator skills, and has long analysis times. This work validated an enzymatic method performed by an automatized spectroscopic apparatus. Method linearity, applicability range, minimum detection limit, the limit of quantification, and repeatability were demonstrated. Therefore, the enzymatic method performed by an automatized spectroscopic apparatus can be used to detect SO2 in vinegar