Abstract We compute the gluon polarization tensor in a thermo-magnetic environment in the strong magnetic field limit at zero and high temperature. The magnetic field effects are introduced using Schwinger’s proper time method. Thermal effects are computed in the HTL approximation. At zero temperature, we reproduce the well-known result whereby for a non-vanishing quark mass, the polarization tensor reduces to the parallel structure and its coefficient develops an imaginary part corresponding to the threshold for quark-antiquark pair production. This coefficient is infrared finite and simplifies considerably when the quark mass vanishes. Keeping always the field strength as the largest energy scale, in the high temperature regime we analyze two complementary hierarchies of scales: q 2 ≪ m f 2 ≪ T 2 and m f 2 ≪ q 2 ≪ T 2. In the latter, we show that the polarization tensor is infrared finite as m f goes to zero. In the former, we discuss the thermal corrections to the magnetic Debye mass.

The thermal and density corrections, in terms of the isospin chemical potential µI , to the mass of the pions, the decay constant and different condensates are studied in the framework of the SU(2) low energy effective chiral Lagrangian at finite temperature in the two phases: The first phase |µI| < m and the second phase |µI|> m, being m the tree-level pion mass. As a function of temperature for µI = 0, the mass remains quite stable, starting to grow for very high values of T, confirming previous results. However, there are interesting corrections to the mass and the other observables mentioned when both effects (temperature and chemical potential) are simultaneously present. At zero temperature the pi± should condense when µI = ± mpi. At finite T, the condensed pion acquires a thermal mass in such a way that a mixture, like in a superfluid, of a condensed and normal phase appears.

In order to achieve a higher sustainability of productive processes, it is necessary to conduct a specific investigation on phytodiversity, allelopathic associations and the methods of maximizing cenotic interactions. With a productive objective in mind, this type of study is necessary for a better understanding of the processes that operate in mixed plantations. It can also facilitate the designs to be used in specific situations and for obtaining the maximum capacities from the site and species. The principles that regulate allelopathic relationships can be studied in different ways such as a laboratory analysis that simulates primary allelopathic effects (direct interactions among species). This is a useful tool for analyzing ecological problems and is undertaken by means of an analysis of data obtained when associating different species in hydroponic culture. This paper presents the obtained results of the reactions of seven species, both native and exotic, under hydroponic conditions and constitutes an indicator of the degree of intra- and inter-specific compatibility of the studied species.

Para orientarse hacia una mayor sostenibilidad de los procesos productivos es necesaria investigación específica sobre fitodiversidad, asociaciones alelopáticas y formas de maximización de las interacciones en la cenosis<A HREF="#r3">*</A>. Este tipo de estudios resulta necesario para un mejor entendimiento de los procesos que operan en las plantaciones mixtas con objetivo productivo, y pueden facilitar los diseños a emplear en situaciones específicas, de modo de potenciar al máximo las capacidades del sitio/especies. Los principios que regulan las relaciones alelopáticas se pueden estudiar de diferentes maneras, una de las cuales es su análisis de laboratorio, simulando efectos alelopáticos primarios (interacciones directas entre especies), que es una de las herramientas para analizar problemas ecológicos. Ello se realiza mediante el análisis de las respuestas obtenidas al asociar diferentes especies en cultivo hidropónico. El trabajo entrega los resultados obtenidos de las reacciones de siete especies, nativas y exóticas, en medio hidropónico, que se constituyen en indicadores del grado de compatibilidad intra e interespecífica de las especies estudiadas.