147 research outputs found
Improved fractional Poincaré type inequalities in John domains
We obtain improved fractional Poincaré inequalities in John domains of a metric space endowed with a doubling measure under some mild regularity conditions on the measure . We also give sufficient conditions on a bounded domain to support fractional Poincaré type inequalities in this setting.Universidad Nacional de La Plata, under grant 11/X805
Universidad de Buenos Aires, under grant 20020120100050BA
Agencia Nacional de Promoción CientÃfica y Tecnológica, under grant PICT 2014-177
Lattice specific heat for the RMIn (R = Gd, La, Y, M = Co, Rh) compounds: non-magnetic contribution subtraction
We analyze theoretically a common experimental process used to obtain the
magnetic contribution to the specific heat of a given magnetic material. In the
procedure, the specific heat of a non-magnetic analog is measured and used to
subtract the non-magnetic contributions, which are generally dominated by the
lattice degrees of freedom in a wide range of temperatures. We calculate the
lattice contribution to the specific heat for the magnetic compounds GdMIn
(M = Co, Rh) and for the non-magnetic YMIn and LaMIn (M = Co, Rh),
using density functional theory based methods. We find that the best
non-magnetic analog for the subtraction depends on the magnetic material and on
the range of temperatures. While the phonon specific heat contribution of
YRhIn is an excellent approximation to the one of GdCoIn in the full
temperature range, for GdRhIn we find a better agreement with LaCoIn,
in both cases, as a result of an optimum compensation effect between masses and
volumes. We present measurements of the specific heat of the compounds
GdMIn (M = Co, Rh) up to room temperature where it surpasses the value
expected from the Dulong-Petit law. We obtain a good agreement between theory
and experiment when we include anharmonic effects in the calculations
Preliminary report on cross-species microsatellite amplification for bumblebee biodiversity and conservation studies
The Iberian Peninsula holds a high diversity of bumblebees but there is a general lack of information about their biodiversity in this area. To overcome this and facilitate conservation studies, we present two novel multiplex assays for the amplification of six and five microsatellite loci respectively. Both assays successfully amplified for most of the studied species in the Iberian populations. Sibling workers and population genetic parameters were analysed in the managed species B. terrestris and in the wild species B. monticola and B. mesomelas, demonstrating the capability of these multiplex assays for biodiversity studies of both managed and wild bumblebee species
Phenotypic and molecular characterization of plants regenerated from non-cryopreserved and cryopreserved wild Solanum lycopersicum Mill. seeds
BACKGROUND: Before cryopreservation is routinely used, its effect on the trueness-to-type of the regenerated plant material needs to be evaluated. OBJECTIVE: In this work, we studied the effect of seed cryopreservation on the phenotypic and molecular characteristics of wild Solanum lycopersicum Mill. plants. METHODS: Thirty-five morphological traits of plants regenerated from cryopreserved seeds were compared to those measured on plants regenerated from non-cryopreserved seeds. RESULT: No statistically significant differences were observed between cryopreserved and non-cryopreserved samples, either in the first or in the second generation post-liquid nitrogen exposure. However, at the molecular level, the genetic analyses performed on the second generation plants germinated from control and cryopreserved seeds using 14 nuclear Simple Sequences Repeats (SSR) markers uncovered some changes in microsatellite length between control and cryopreserved samples. These results confirm at the botanical phenotype level the effectiveness of seed cryostorage for conservation and regeneration of true-to-type S. lycopersicum plants. CONCLUSION: Further experiments are required to clarify potential phenotypic effects of the changes observed in the DNA
Phenotypic and molecular characterization of Phaseolus vulgaris plants from non-cryopreserved and cryopreserved seeds
The objective of this work was to evaluate if cryostorage of Phaseolus vulgaris L. seeds induced variations in regenerated plants at the phenotypic and molecular levels. A series of agricultural traits was measured on plants grown from control, non-cryopreserved and cryopreserved seeds, and the genetic stability of plants of the second generation was analysed at selected microsatellite loci. The phenotype of the second generation plants was evaluated as well. No statistically significant phenotypic differences were observed for the parameters measured, neither in the first nor in the second generations. Averaging both treatments, about 76% of the seeds had germinated 10 days after sowing. At harvest we recorded plants with about 73 cm in height, 13 stem internodes, 25 fruits, 103 grains and 4 grains per fruit. One hundred seeds weighted about 26 g. The genetic analyses performed on the second generation plants using six nuclear Simple Sequences Repeats (SSR) markers revealed no changes in microsatellite length between control and cryopreserved samples, implying that there was no effect of seed liquid nitrogen exposure on genome integrity. The phenotypic and molecular results reported here confirm that cryostorage is an efficient and reliable technique to conserve P. vulgaris seeds and regenerate true-to-type plants
La relación entre el crecimiento económico y la degradación medioambiental
El fuerte incremento de la degradación medioambiental a causa del desarrollo humano y económico ha provocado el surgimiento de una gran preocupación por la preservación del medioambiente durante las últimas décadas. Esta preocupación se ha traducido en la elaboración de muchos estudios que intentan descubrir cuál es la relación entre el crecimiento económico y la degradación medioambiental. La hipótesis más comentada y contrastada es la de la Curva de Kuznets Ambiental (CKA) que prevé que en bajos niveles de renta per cápita el crecimiento económico aumentará la degradación medioambiental hasta llegar a un nivel de renta per cápita en el que empezará a caer esta degradación medioambiental con el crecimiento económico. Es decir, que el crecimiento económico y la degradación medioambiental guardan una relación en forma de U-invertida. En este trabajo se revisa la literatura acerca de esta hipótesis, los conceptos en los cuales se sustenta, la metodologÃa usada para contrastarla, las hipótesis que la complementan, la controversia que genera y la evidencia empÃrica que la acompaña. Para complementar este último apartado también se realiza un pequeño estudio en el que se estima un modelo empÃrico para 11 paÃses de 1990 a 2014. Las principales conclusiones a las que se llega es que, aunque haya evidencia empÃrica de la existencia de la CKA para algunos paÃses e indicadores de degradación medioambiental, no parece ser una hipótesis generalizable a todos los paÃses e indicadores. Además, no se garantiza que el crecimiento económico sea el causante de una disminución de la degradación medioambiental y por eso es necesaria la actuación de las instituciones públicas para asegurar la preservación del medioambiente
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