Comunidades virtuales de aprendizaje colaborativo para la educación superior

This article aims to outline and project three new learning scenarios for Higher Education that, after the emergence of ICT and communication through the Network-lnternet, have come under the generic name of virtual communities. To that end, we start from a previous conceptual analysis on collaborative learning, cooperative learning and related concepts taking place in these communities and serving as a basis for sorting them into three types in particular: communities of educational work of professional practice and scientific knowledge. Virtual communities where the activities undertaken and skills acquired are set as important parts of our personal learning development, wich are necessary to build the Knowledge Society.El presente artículo tiene como objetivo esbozar y proyectar tres nuevos escenarios de aprendizaje para la Educación Superior que, tras la irrupción de las TIC y la comunicación a través de la Red-lnternet, han surgido con el nombre genérico de comunidades virtuales. Para ello, se parte de un análisis previo de carácter conceptual sobre el aprendizaje colaborativo, aprendizaje cooperativo y otros conceptos afines que tienen lugar en estas comunidades y   que sirven de base para clasificarlas de forma específica en tres tipos: comunidades de tarea educativa, práctica profesional y conocimiento científico. Comunidades virtuales en donde las actividades a realizar y las competencias a adquirir se plantean como piezas importantes de nuestras trayectorias personales de aprendizaje, necesarias para construir la Sociedad del Conocimiento.El presente artículo tiene como objetivo esbozar y proyectar tres nuevos escenarios de aprendizaje para la Educación Superior que, tras la irrupción de las TIC y la comunicación a través de la Red-lnternet, han surgido con el nombre genérico de comunidades virtuales. Para ello, se parte de un análisis previo de carácter conceptual sobre el aprendizaje colaborativo, aprendizaje cooperativo y otros conceptos afines que tienen lugar en estas comunidades y   que sirven de base para clasificarlas de forma específica en tres tipos: comunidades de tarea educativa, práctica profesional y conocimiento científico. Comunidades virtuales en donde las actividades a realizar y las competencias a adquirir se plantean como piezas importantes de nuestras trayectorias personales de aprendizaje, necesarias para construir la Sociedad del Conocimiento

Interpretaciones de trabajos de fertilización con Solanaceae en Puerto Rico

One approach for the development of fertilizer recommendations is based on field-measured yield response to added fertilizer.The crop nutrient requirement (CNR) is the total amount of that element needed by the crop during the production season to produce optimum economic yield, and is equivaient to the fertilizer rate above which no significant increase in yield occurs. Published and unpublished fertilization research done in Solanaceae, tomato (Lycopersicon esculentum), eggplant (Solarium melongena), and sweet pepper (Capsicum annuum), in Puerto Rico over the past 25 years was used to calculate CNR values for nitrogen (N), phosphorus (P) and potassium (K). The mean yields obtained from each fertilizer treatment were converted from a unit area basis (ton/ha or kg/ha) to percentage relative yield (RY). The RYs were then plotted against rates of nutrient applied and fitted to linear, quadratic, linear-plateau, quadratic-plateau, exponential, and Cate-Nelson models to determine CNR values. Plant response to K was not observed in soils dominated by 2:1 clays (2:1 clay soils). Large variability and few experimental data points precluded fitting equations to the data in soils dominated by 1:1 clays (1:1 clay soils). For P and N, predicted CNR values varied widely, depending on the selected model. The best model was selected on the basis of coefficients of determination, standardized residual plots, and was corroborated with economic returns. For 1:1 clay soils, predicted CNR values were 113 and 255 kg P2Os/ha and 150 and 207 kg N/ha for the Cate-Nelson and quadratic models, respectively. For 2:1 clay soils, predicted CNR values were 50 and 148 kg P205/ha for the Cate-Nelson and finear- plateau models, respectively, and 50 and 120 kg N/ha for the Cate- Nelson and exponential models, respectively.Una metodología para realizar recomendaciones de fertilización se basa en relaciones entre niveles de fertilización y medidas correspondientes de rendimiento. El requisito nutricio nal del cultivo (RNC) es la totalidad del elemento que requiere el cuítivo durante el ciclo de producción para producir rendimientos económicos óptimos, y es equivalente al nivel de fertilización (cuando el suelo suple poca o ninguna cantidad del nutrimento) por encima del cual no existe un aumento significativo en rendimiento. Investigaciones realizadas con la familia Soianaceae: tomate (Lycopersicon esculentum), berenjena (Solatium melongena), y pimiento (Capsicum annuum) en Puerto Rico se utilizaron para calcular valores de RNC para nitrógeno (N), fósforo (P) y potasio (K). Los valores promedios obtenidos de cada nivel de fertilización fueron convertidos de unidad por área (ton/ha, kg/ha, cajas/acre) a rendimiento relativo (RR). Los valores de RR fueron grafícados contra niveles de aplicación de nutrimentos y se ajustaron diferentes modelos (lineal, cuadrática, iineai-meseta, cuadrático-meseta, exponencia! y Cate-Nelson) para determinar los vaiores de RNC. No se observó respuesta a la aplicación de K en suelos dominados por arcillas 2:1 (suelos 2:1). En suelos dominados por arcillas 1:1 (suelos 1:1) ninguna de las ecuaciones se ajustó adecuadamente a los datos porque había pocos datos experimentales y alta variabilidad entre los valores de rendimiento. Para P y N, los valores de RNC predichos variaron según el modelo utilizado. El mejor modelo se escogió basándose en los coeficientes de determinación y gráficos de residuales estandarizados, y corroborados con retornos económicos. En ¡os suelos 1:1, los valores de RNC predichos fueron 113 y 255 kg P205/ha y 150 y 207 kg N/ha para los modelos Cate-Nelson y cuadrático, respectivamente. En los suelos 2:1, los valores predichos fueron 50 y 148 kg P2Os/ha para los modelos Cate-Nelson y lineal-meseta, respectivamente, y 50 y 120 kg N/ha para los modelos Cate-Nelson y exponencial, respectivamente

“Galectin-1 Induces Central and Peripheral Cell Death: Implications in T-Cell Physiopathology”

The immune system has a remarkable capacity to maintain a state of equilibrium even as it responds to a diverse array of foreign proteins and despite its contact exposure to self-antigens. Apoptosis is one of the mechanisms aimed at preserving the homeostasis after the completion of an immune response, thus returning the immune system to a basal state and warranting the elimination of autoagressive cells in both central and peripheral lymphoid organs. Targeted deletions in critical genes involved in the apoptotic death machinery together with natural spontaneous mutations have clearly shown the importance of apoptosis in the regulation of the immune response. This complex scenario of stimulatory and inhibitory genes has been enriched with the finding that galectin-1, a 14.5 kDa β-galactoside-binding protein, is able to induce apoptosis of immature cortical thymocytes and mature T cells by cross-linking cell surface glycoconjugates. Galectin-1 is present not only in central and peripheral lymphoid organs, but also at sites of immune privilege. In the present article we will discuss the implications of galectin-1-induced apoptosis in T-cell physiopathology in an attempt to validate its therapeutic potential in autoimmune and inflammatory diseases

Supercritical colliding wind binaries

Context. Particle-accelerating colliding-wind binaries (PACWBs) are systems that are formed by two massive and hot stars and produce nonthermal (NT) radiation. The key elements of these systems are fast winds and the shocks that they create when they collide. Binaries with nonaccreting young pulsars have also been detected as NT emitters, again as a consequence of the wind-wind interaction. Black holes (BHs) might produce NT radiation by this mechanism if they accrete at super-Eddington rates. In such cases, the disk is expected to launch a radiation-driven wind, and if this wind has an equatorial component, it can collide with the companion star yielding a PACWB. These systems are supercritical colliding wind binaries (SCWBs). Aims. We aim to characterize the particle acceleration and NT radiation produced by the collision of winds in binary systems composed of a superaccreting BH and an early-type star. Methods. We estimated the terminal velocity of the disk-driven wind by calculating the spatial distribution of the radiation fields and their effect on disk particles. We then found the location of the wind collision region and calculated the timescales of energy gain and losses of relativistic particles undergoing diffusive acceleration. With this information, we were able to compute the associated spectral energy distribution of the radiation. Results. We find that the interaction of winds can produce NT emission from radio up to tens of GeV, with luminosities in the range of $\sim 10^{33}-10^{35} \, {\rm erg \, s^{-1}}$, which for the most part are contributed by electron synchrotron and inverse Compton radiation. Conclusions. We conclude that SCWBs, such as some ultraluminous X-ray sources and some Galactic X-ray binaries, are capable of accelerating cosmic rays and producing NT electromagnetic emission from radio to $\gamma$-rays, in addition to the thermal components.Comment: 13 pages, 10 figures. Accepted for publication in Astronomy and Astrophysic

Mexico and the European Union trade renegotiation of 2020: A deep integration agreement Version 2.0?

After more than 20 years of trade integration, Mexico and the European Union (EU) started renegotiating the accord in 2016 and concluded in 2020. The treaty signed in 2000 corresponds to a series of deep integration agreements that seek to go further than the liberalization of goods, services, and investments and aspire to be more of an understanding of cooperation in several policy areas. Mexico joined the agreement to achieve more diversified exports to offset Mexico's dependence on the US market and to include other spheres besides trade. The EU found in Mexico a trade partner with a strategic geographical location to access the US and Canadian markets. Likewise, the EU would benefit from the liberalized Mexican financial market with potential profits in the financial and telecommunication sectors. This work reviews the agreement in 2020 from the deep integration agreement framework lens. We examine to what extent these provisions provide the conditions for a deep integration that benefits both regions. We also analyze whether the renegotiation of 2020 can be seen as an attempt to further this cooperation process and the economic implications for Mexico. We argue in this paper that the former Free Trade Agreement between the European Union and Mexico (FTA-EU-MX) consolidated a trade pattern that existed before the agreement with EU multinationals concentrated in critical industrial sectors, without significant trade creation for medium and small businesses. This result confirms that there have been advances in shallow integration but no substantial changes in cooperation or deep integration. After analyzing the 2020 renegotiation text, we conclude that Mexico could achieve significant gains in areas of cooperation as the 2020 text has more enforceable policies, which was not the case with the 2000 treaty.  Keywords: deep integration, Mexico, European Union, international cooperation JEL: F10, F15, F5

Radiative model for the microquasar SS433: Non-thermal emission from the eastern jet

In this work we propose a lepto-hadronic model for the non-thermal emission of the eastern jet of the galactic microquasar SS433. We obtain that the flux in TeV reported by the HAWK Collaboration can beexplained by the decay of neutral pions produced in inelastic collisions proton-proton. Radio and X-ray emission is correctly fitted by synchrotron radiation of relativistic primary electrons.Fil: Sotomayor Checa, Pablo Omar. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Romero, Gustavo E.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina62º Reunión Anual de la Asociación Argentina de AstronomíaBuenos AiresArgentinaAsociación Argentina de Astronomí

Mechanical oscillations in lasing microspheres

We investigate the feasibility of activating coherent mechanical oscillations in lasing microspheres by modulating the laser emission at a mechanical eigenfrequency. To this aim, 1.5% Nd3+:Barium-Titanium-Silicate microspheres with diameters around 50 {\mu}m were used as high quality factor (Q>10^6) whispering gallery mode lasing cavities. We have implemented a pump-and-probe technique in which the pump laser used to excite the Nd3+ ions is focused on a single microsphere with a microscope objective and a probe laser excites a specific optical mode with the evanescent field of a tapered fibre. The studied microspheres show monomode and multi-mode lasing action, which can be modulated in the best case up to 10 MHz. We have optically transduced thermally-activated mechanical eigenmodes appearing in the 50-70 MHz range, the frequency of which decreases with increasing the size of the microspheres. In a pump-and-probe configuration we observed modulation of the probe signal up to the maximum pump modulation frequency of our experimental setup, i.e., 20 MHz. This modulation decreases with frequency and is unrelated to lasing emission, pump scattering or thermal effects. We associate this effect to free-carrier-dispersion induced by multiphoton pump light absorption. On the other hand, we conclude that, in our current experimental conditions, it was not possible to resonantly excite the mechanical modes. Finally, we discuss on how to overcome these limitations by increasing the modulation frequency of the lasing emission and decreasing the frequency of the mechanical eigenmodes displaying a strong degree of optomechanical coupling.Comment: 17 pages, 5 figure

Hairy black holes by gravitational decoupling

Black holes with hair represented by generic fields surrounding the central source of the vacuum Schwarzschild metric are examined under the minimal set of requirements consisting of i) the existence of a well defined event horizon and ii) the strong or dominant energy condition for the hair outside the horizon. We develop our analysis by means of the gravitational decoupling approach. We find that trivial deformations of the seed Schwarzschild vacuum preserve the energy conditions and provide a new mechanism to evade the no-hair theorem based on a primary hair associated with the charge generating these transformations. Under the above conditions i) and ii), this charge consistently increases the entropy from the minimum value given by the Schwarzschild geometry. As a direct application, we find a non-trivial extension of the Reissner-Nordstrom black hole showing a surprisingly simple horizon. Finally, the non-linear electrodynamics generating this new solution is fully specified.Comment: 11 pages, 4 figure