On the generalized Feng-Rao numbers of numerical semigroups generated by intervals

We give some general results concerning the computation of the generalized Feng-Rao numbers of numerical semigroups. In the case of a numerical semigroup generated by an interval, a formula for the $r^{th}$ Feng-Rao number is obtained.Comment: 23 pages, 6 figure

El trabajo en equipo en un entorno virtual de aprendizaje

A pesar de que el trabajo en equipo es una competencia transversal interpersonal presente en la práctica totalidad de los Grados de Derecho, constituye una de las competencias con la que tanto docentes como estudiantes se encuentran menos familiarizados. A estos efectos, la utilización de las tecnologías de la información y la comunicación pueden facilitar el desarrollo de esta competencia. A la hora de planificar el trabajo en equipo, cuestión compleja, además del diseño de las actividades y la evaluación y la selección de las herramientas informáticas, el docente deberá determinar algunas cuestiones como el lugar y momento de su realización o los criterios para la formación de los grupos

Evaluación del comportamiento a la fatiga de másticos bituminosos reforzados con poliolefinas a través de una metodología basada en energía disipada

Polymers are known to improve the fatigue resistance of sphalt mastics. However, undesirable results can be obtained if the polymer is not successfully integrated into the bitumen binder. The goal of this work is to evaluate the effect of the addition of three selected polyolefins on their mastic’s fatigue performance. Low and high density polyethylenes (LDPE and HDPE) and polypropylene (PP) were chosen and used at the concentration of 4 wt.%. A dissipated energy approach was used in order to analyze the fatigue resistance, at 25 ºC, of the three composites studied. Dynamic time sweeps at and above the linear viscoelastic threshold were carried out. Based on that, the results demonstrated a better improvement when the LDPE was considered. For that binder, fluorescence optical microscopy observations at 25 ºC provided morphological evidence of a more homogeneous bitumen-polymer distribution which could be behind the improved fatigue behavior.El uso de polímeros mejora la resistencia a la fatiga de los másticos asfálticos. Sin embargo, se pueden obtener resultados no esperados si el polímero no se integra eficientemente en el ligante bituminoso. El objetivo de este trabajo es evaluar el efecto de la adición de 3 poliolefinas sobre el comportamiento a la fatiga. Se seleccionaron polietilenos de baja y alta densidad (PEBD y PEAD) y polipropileno (PP) que se usaron al 4 % en peso. Se empleó una metodología basada en la energía disipada, a 25 ºC. Se realizaron ensayos dinámicos de barrido de tiempo en el límite y por encima del intervalo de viscoelasticidad lineal, que demostraron un mejor comportamiento para el mástico que contenía PEBD. Para él, se observó a través de microscopía óptica de fluorescencia que la distribución de polímero en el betún era mucho más homogénea, y éste podría ser el motivo del comportamiento mejorado

The adsorbent capacity of growing media does not constrain myo-inositol hexakiphosphate hydrolysis but its use as a phosphorus source by plants

Aims The hydrolysis of organic P in soils is a relevant aspect contributing to the supply P to plants, which is affected by adsorbent capacity and biological properties of soils. This work aimed at studying the contribution of phytate to plant nutrition as affected by Fe oxides and phosphohydrolases releasing microorganisms in the growing medium. Methods An experiment with cucumber and myo-inositol hexakiphosphate (myo-Ins6P) as P source was performed involving two factors: Fe oxide –ferrihydrite– rates (0, 100, 300 mg kg−1 of citrate–ascorbate extractable Fe), and microbial inoculation (Trichoderma asperellum T34, Bacillus subtilis QST713, and noninoculated). Results P uptake decreased with increased Fe oxides in the growing media. Phytase activity and organic anions concentration increased with increased Fe oxides in the media. Most of the P supplied was recovered as inorganic P at the highest Fe oxide concentration. Inoculants did not improve P uptake by plants, despite B. subtilis promoted an enhanced hydrolytic activity at the highest Fe oxide concentration. Conclusions An increased adsorption capacity of the growing media restricts the use of myo-Ins6P as P source by plants. This was not the result of its stabilization through adsorption or a decreased hydrolytic activity, but of the adsorption of inorganic P on Fe oxides after hydrolysis

Differing Presynaptic Contributions to LTP and Associative Learning in Behaving Mice

The hippocampal CA3-CA1 synapse is an excellent experimental model for studying the interactions between short- and long-term plastic changes taking place following high-frequency stimulation (HFS) of Schaffer collaterals and during the acquisition and extinction of a classical eyeblink conditioning in behaving mice. Input/output curves and a full-range paired-pulse study enabled determining the optimal intensities and inter-stimulus intervals for evoking paired-pulse facilitation (PPF) or depression (PPD) at the CA3-CA1 synapse. Long-term potentiation (LTP) induced by HFS lasted ≈10 days. HFS-induced LTP evoked an initial depression of basal PPF. Recovery of PPF baseline values was a steady and progressive process lasting ≈20 days, i.e., longer than the total duration of the LTP. In a subsequent series of experiments, we checked whether PPF was affected similarly during activity-dependent synaptic changes. Animals were conditioned using a trace paradigm, with a tone as a conditioned stimulus (CS) and an electrical shock to the trigeminal nerve as an unconditioned stimulus (US). A pair of pulses (40 ms interval) was presented to the Schaffer collateral-commissural pathway to evoke field EPSPs (fEPSPs) during the CS-US interval. Basal PPF decreased steadily across conditioning sessions (i.e., in the opposite direction to that during LTP), reaching a minimum value during the 10th conditioning session. Thus, LTP and classical eyeblink conditioning share some presynaptic mechanisms, but with an opposite evolution. Furthermore, PPF and PPD might play a homeostatic role during long-term plastic changes at the CA3-CA1 synapse

Facies oncolíticas en medio continental: Aplicación al sector SE de la Cuenca del Duero

Se estudian oncolitos s. l. del borde S. de la Cuenca del Duero (Sector Oriental). Aparecen en dos tipos de yacimientos: l. En niveles continuos a escala de corte, pero no a escala de Km., construyendo biomimicritas asociadas a facies lacustres. 2. En "barras" y canales a diferentes alturas en el tránsito de facies de abanico a aluvial-facies lacustres. Los del primer tipo se adaptan al modelo de LOGAN, et al. (1964); en el segundo aparecen también individuos con microestructura arborescente, sólo citada en algunos estromatolitos actuales; para dichos "oncolitos" proponemos un modelo de génesis. Logramos aislar mediante ataque úcido lento el componente orgánico (tricomas de diferente grosor y longitud) de ambas facies. Se discute el valor taxonómico de sus caracteres observables y el de las texturas asociadas