La protección de los socios externos en los grupos de sociedades en el Anteproyecto de Ley de Código Mercantil

El presente artículo se centra en el análisis de algunas cuestiones que suscita el régimen proyectado de los grupos de sociedades en el Anteproyecto de Ley de Código Mercantil de 30 de mayo de 2014. Se estudian las medidas de tutela de los socios externos; en concreto, el deber de información de la pertenencia al grupo, la acción de responsabilidad en defensa del interés social de la sociedad dependiente, el derecho de separación, la indemnización en caso de adquisición por la sociedad dominante de la totalidad del capital social de la sociedad dependiente y, por último, el derecho de información contable. En todos los temas se han tenido en cuenta el Derecho de sociedades vigente, el Derecho proyectado y las aportaciones de la jurisprudencia y la doctrina

Autonomous navigation and guidance for CubeSats to flyby near-Earth asteroids

Recent advancements in CubeSat technology unfold new mission ideas and the possibility to lower the cost of space exploration. Exploiting the natural dynamics around the Sun-Earth barycentric Lagrange points, minimal-ΔV trajectories to flyby asteroids appear which are compatible with current CubeSat propulsive capabilities. Ground operations costs for an interplanetary CubeSat, however, still represent a major challenge towards low-cost missions; hence certain levels of autonomy are desirable. Considering the limited allocation of sensors and actuators in CubeSats, and their limited performance, Monte Carlo simulations are implemented to understand the flyby accuracies that can be achieved through autonomous navigation and guidance. Primary sources of error analyzed in this study include: (1) uncertainties in the departure conditions, (2) errors in the propulsive maneuvers, (3) errors in the observations, and (4) uncertainties in the ephemeris of the target asteroid. An autonomous navigation and guidance strategy is proposed and evaluated, employing observations of the Sun, visible planets and of the target asteroid, and two trajectory correction maneuvers along the trajectory. Flyby accuracies below 100 km are found possible if the mission characteristics are suitable in terms of available ΔV, on-board asteroid visibility time, mission duration, and asteroid ephemeris uncertainty before the mission. Ultimately, this study assesses the readiness level of current CubeSat technology to autonomously flyby near-Earth asteroids, with realistic component specifications and modeling of relevant errors and uncertainties. The effect of the different mission factors on the final flyby accuracies is evaluated, and a feasible autonomous navigation and guidance strategy is proposed in the effort to reduce ground operations and overall mission costs

Uso de las Fake News en la campaña presidencial de Iván Duque y Gustavo Petro

Analizar las estrategias utilizadas por los partidos Colombia Humana y Centro Democrático en la campaña electoral de la segunda vuelta para la presidencia de Colombia (2018-2022) en la red social Facebook.Este documento presenta el resultado de la investigación titulada “Uso de la Fake News en la campaña de la segunda vuelta presidencial entre Iván Duque y Gustavo Petro”, este trabajo pretende dar cuenta de la influencia que tienen las redes sociales en la población votante de Colombia, y como el fenómeno de las Fake News se ha convertido en un punto de partida para varias campañas presidenciales, afectando de manera negativa o `positiva el concepto político de los usuarios de las redes, generando una opinión tergiversada a los usuarios de Facebook; Este texto busca también, aclarar conceptos propios con relación a el uso de las nuevas tecnologías, la comunicación, las tipologías de las redes entre otros acercamientos epistemológicos, esto enmarcado en las sociedades de consumo

Communication strategies for colonization mission to Mars

Earth-Mars cycler trajectories could be used as a periodic and cost-efficient human transportation system from Earth to Mars in a future mission to colonize Mars. Continuous and reliable communication between Mars and the Earth will be required in such a mission. In a circular-coplanar model, the existance of a particularly interesting cycler trajectory (ballistic outbound Earth-Mars S1L1 cycler trajectory) is proven, which has relatively short Earth-Mars transfer times, low relative velocities with respect to the planets at the encounters, and an intermediate Earth encounter within every two-synodic-period cycle. Two outbound Earth-Mars S1L1 cycler vehicles launched one synodic period apart could be used to maximize the number of trips from Earth to Mars. A new and economic method to maintain communication over periods of direct Earth-Mars link blockage (i.e. Earth-Mars solar conjunction) is introduced for a mission such that two outbound Earth-Mars S1L1 cycler vehicles are used for human transportation to Mars, using the cycler vehicles also as communication relays to avoid the need of a heliocentric communications satellite constellation to communicate from and to Mars. The analysis is performed in a circular-coplanar model and in a more realistic model (i.e. ephemeris model for the states of Earth and Mars, and STOUR results for the orbit parameters of the cycler trajectories). Continuous communication with only one cycler vehicle in orbit is proven not to be possible. In a mission with permanent human settlements on Mars and Phobos (inside Stickney Crater), two two-satellite Mars-centered communication constellations are designed (in a circular-coplanar model) to continuously communicate the colonies on Phobos and Mars, and the Earth (directly or through the cycler vehicles), which could avoid the need of a three- or four-satellite constellation around Mars. A communication constellation consisted of two satellites in a stationary orbit around Mars is determined to be a more cost-efficient solution than two satellites in Phobos’ orbit. The link performance of each of the communication links is analyzed for the communication architecture composed of two areostationary satellites, the colonies on Mars and Phobos, two cycler vehicles and the ground stations on Earth. Power requirements, antenna sizes and frequency are estimated for a demanding HDTV transmission from Mars and Phobos to Earth.Ingeniería Aeroespacia

CubeSat autonomous navigation and guidance for low-cost asteroid flyby missions

Recent advancements in CubeSat technology unfold new mission ideas and the opportunity to lower the cost of space exploration. Ground operations costs for interplanetary CubeSats, however, still represent a challenge toward low-cost CubeSat missions: hence, certain levels of autonomy are desirable. The feasibility of autonomous asteroid flyby missions using CubeSats is assessed here, and an effective strategy for autonomous operations is proposed. The navigation strategy is composed of observations of the Sun, visible planets, and the target asteroid, whereas the guidance strategy is composed of two optimally timed trajectory correction maneuvers. A Monte Carlo analysis is performed to understand the flyby accuracies that can be achieved by autonomous CubeSats, in consideration of errors and uncertainties in a) departure conditions, b) propulsive maneuvers, c) observations, and d) asteroid ephemerides. Flyby accuracies better than ±100  km (3σ)" role>±100  km (3σ)±100  km (3σ) are found possible, and main limiting factors to autonomous missions are identified, namely a) on-board asteroid visibility time (Vlim≥11" role=>Vlim≥11Vlim≥11), b) ΔV" role=">ΔVΔV for correction maneuvers (>15  m/s>15  m/s), c) asteroid ephemeris uncertainty (<1000  km<1000  km), and d) short duration of transfer to asteroid. Ultimately, this study assesses the readiness level of current CubeSat technology to autonomously flyby near-Earth asteroids, in consideration of realistic system specifications, errors, and uncertainties

Removal of emerging pollutants in conventional and microalgae based biotechnology urban wastewater treatment plants

Wastewater treatment plants (WWTPs) reduce portion of the input of pharmaceuticals in aquatic systems, but there is no data available about the elimination of emerging contaminants with microalgae technology. The aim of this work was to determine the average mass flows and concentrations of pharmaceuticals in influents and effluents from two sewages treatment plants using conventional and microalgae based biotechnologies and to compare the removal of pharmaceuticals using both depuration technologies. Only between 20 to 60% of five pharmaceuticals groups is reduce in both WWTP using conventional technologies consisting of a pretreatment, primary settling and secondary treatment by aerobic biological reactor. Using microalgae based biotechnologies efficiency of removal pharmaceuticals is higher than conventional technologies and it increase by using DAF (Dissolve Air Flotation) technology to separate algae biomass

Stand density management diagram and its thinning applications in Drimys winteri second-growth forests in southern Chile

Stand density management (DMD) diagrams are graphical models of uniform stands at different ages that reflect the relationship among size, density, competition, site occupancy and self thinning. DMDs allow planning of thinnings through the definition of a target stand and the upper and lower limits of site occupancy. In this study we developed a DMD for Drimys winteri second-growth forests in southern Chile by using 300 sampling units with at least 70 % basal area of this species. The resulting DMD allowed the determination of the maximum density line, the volume and height isolines, and the evaluation of its use with information from permanent plots thinned 21 years ago. The results of the functions in the DMD present acceptable predictive power, and illustrate the usefulness and precision of this tool to plan silviculture activities. Results from applying the DMD suggest maintenance of site occupancy levels between the subutilization zone (30 % relative density index (RDI)) and the imminent mortality zone (45 % IDR), executing at least three thinnings to reach a target stand that will produce sawtimber and veneer at an age of at least 80 years for the study site. With this scheme the windfall risk is reduced and therefore so is the potential loss of production.Los diagramas de manejo de la densidad (DMD) son modelos gráficos de la dinámica de rodales uniformes a diferentes edades que reflejan la relación entre tamaño, densidad, competencia, ocupación del sitio y autorraleo; y permiten la planificación de raleos mediante la definición de un rodal meta y los límites superior e inferior de ocupación del sitio. Este estudio desarrolló un DMD para renovales de Drimys winteri en el sur de Chile, utilizando 300 unidades muestrales con una participación mayor a 70 % de área basal de D. winteri, que permitió determinar las líneas de tamaño máximo densidad, las isolíneas de volumen, isolíneas de altura, y evaluar su uso con datos de parcelas permanentes de raleo medidos durante 21 años. Los resultados de las funciones que conforman el DMD presentan aceptables capacidades predictivas, constatando la utilidad y precisión de esta herramienta para planificar intervenciones silviculturales. Los resultados de la aplicación del DMD sugieren mantener niveles de ocupación de sitio entre las zonas de subutilización (índice de densidad relativa (IDR) de 30 %) y la de inminente mortalidad por competencia (IDR de 45 %), realizando al menos tres raleos para alcanzar un rodal meta que genere productos aserrables y debobinables a una edad no menor a los 80 años para el sitio analizado. Con este esquema se reduce el riesgo de caída de árboles por viento y la pérdida de producción física del sitio

Financial evaluation of management in secondary forests of canelo (Drimys winteri) in the Coastal Range of Valdivia, Chile

Young secondary forests of Drimys winteri have excellent growth and regeneration, and cover an area of 230,000 hectares in Chile. However, there is no supply of high-value timber to feed the growing market opportunities. The objective of this study was to evaluate the profitability of thinning trials in secondary forests of Drymis winteri in a medium-productivity site. The thinning treatments were considered late thinning, and were named as moderate thinning (E1), heavy (E2) and heavy (E3), in addition to a control treatment (E4). The yield was determined using the net present value (NPV), land expected value (LEV), and modified internal rate of return (MIRR), incorporating discount rates of 6 %, 8 % and 10 % and low administration costs in two scenarios, no costs before thinning (S1) and costs since the establishment of the stand (S2). The results for the NPV and VPS in S2 were negative, in contrast with S1, which doubled its profitability compared with the control treatment. The E2 treatment had the highest profitability in the S1 case, with a NPV of USD 2,724 ha–1, a VPS of USD 3,771 for a 6 % rate, and a MIRR of 19 %. For an operational level the moderate thinning treatment (E1) is desirable since it reduces the risk of windfall, generates the highest yield in volume, and profitability values slightly lower than E2.Los bosques secundarios de canelo presentan excelentes crecimientos y regeneran fácilmente en forma natural, alcanzando una superficie de 230.000 hectáreas en Chile. A pesar de ello, no existe una oferta de madera que permita aprovechar las oportunidades de los mercados nacionales e internacionales. El objetivo de este estudio fue evaluar la rentabilidad de ensayos de raleo en bosques secundarios de Drimys winteri en un sitio de productividad media. Los tratamientos corresponden a raleos aplicados tardíamente, denominados como raleo moderado (E1), fuerte (E2 y E3) y un tratamiento control (E4). La rentabilidad se determinó a través del valor actual neto (VAN), valor económico del suelo (VES) y la tasa interna de retorno modificada (TIRm) incorporando tasas de descuento de 6 %, 8 % y 10 %; se consideraron costos de administración bajo dos escenarios: sin costo antes de las intervenciones (S1) y con costo desde el establecimiento del rodal (S2). Los resultados para el VAN y VPS en S2 fueron negativos, a diferencia del S1 que duplicó al menos su rentabilidad respecto de no intervenir los bosques secundarios. El tratamiento E2 presentó la mayor rentabilidad para el supuesto S1 con un VAN de US$2.724 ha–1, un VPS de US$ 3.771 para una tasa de 6 % y una TIRm de 19 %. Es recomendable para un nivel operacional el tratamiento de raleo moderado (E1), ya que reduce el riesgo de caída por viento, genera el mayor rendimiento en volumen y presenta cifras de rentabilidad levemente inferiores a E2

Asteroid flyby opportunities using semi-autonomous CubeSats: mission design and science opportunities

CubeSat technology has recently attracted great interest from the scientific community, industry and space agencies, and represents today an exciting movement towards a more affordable and accessible space industry. In view of potential applications of CubeSat technology to small-body planetary exploration, this paper studies the feasibility of using autonomous CubeSats to flyby near-Earth asteroids. This work provides an overview of the current state of CubeSat technology and proposes a 3U CubeSat mission using primarily off-the-shelf components. The proposed mission considers a CubeSat is deployed by a larger spacecraft in a periodic orbit around the first (L1) or the second (L2) Sun-Earth Lagrange points (common destinations to observe the Sun and outer space), from where fuel-optimal impulsive trajectories are designed to flyby asteroids between 2019 and 2025. Navigation support and ground operations costs still represent a major challenge for interplanetary CubeSats. As such, Monte Carlo simulations are performed to determine the flyby accuracies that can be accomplished by a 3U CubeSat flying autonomously (i.e., using observations of the Sun during cruise and observations of the asteroid before the flyby to estimate its own trajectory, instead of using ground stations for navigation support). Asteroid flyby opportunities for an autonomous 3U CubeSat are identified between years 2019 and 2025. Flyby altitudes below 500 km are found possible with currently-available CubeSat components. Possible science payloads are also overviewed, and the potential scientific return of such a low-cost mission is discussed

Aproximación a la arquitectura de COVAG: criterios de diseño en la obra arquitectónica de Julio Valdivieso

Esta investigación estudia la obra del arquitecto Julio Valdivieso en Cuenca, Ecuador. En colaboración con su socio el Ing. Claudio Corral y a través de su compañía COVAG, construyó una serie de proyectos arquitectónicos de diferente índole como: vivienda unifamiliares, multifamiliares, edificios en altura, oficinas, comercios y readecuaciones, estos tienen el valor y el bagaje para ser objeto de estudio porque los proyectos fueron parte de la historia del desarrollo inmobiliario de la ciudad entre los años 1971-2008. Ciento cincuenta proyectos fueron numerados, localizados y catalogados en una base de datos que contiene información y datos importantes sobre cada proyecto, cuarenta y ocho de los proyectos fueron seleccionados para ser reconstruidos digitalmente en tres dimensiones con el propósito de evidenciar la evolución arquitectónica a través del tiempo. De estos proyectos dos se seleccionaron para ser analizados con mayor profundidad basándose en el método de investigación de Cristina Gastón evaluando forma, contexto, programa, estructura y tecnología, del estudio se extraen los criterios de diseño de Julio Valdivieso obteniendo como resultado todos los rasgos de sus proyectos y un documento con información valiosa sobre la arquitectura moderna en Cuenca.This investigation studies the work of the architect Julio Valdivieso in Cuenca, Ecuador. With his partner the engineer Claudio Corral through their company COVAG, he built a series of architecture projects as: single family dwellings, multiple family housing, multistorey buildings, offices, commercials and remodelations, these have the academic and technical value to be analyzed since they are part of the history in the development of the city between the years 1971 and 2008. One hundred and fifty projects have been numbered, located and cataloged in a database which contains important information about each project, forty-eight projects were selected to be digitally rebuilt in three dimensions with the purpose to witness his architectural evolution in form and technology based on Cristina Gaston’s research method. Two of these projects were deeply studied and analyzed to extract the design concepts of Julio Valdivieso in all his projects. Obtaining as a result the main characteristics and features of his buildings and a document that contains valuable information about modern architecture in Cuenca.ArquitectoCuenc