Análisis del efecto de diferentes programas de temperatura en la fabricación de polímeros celulares

Este trabajo estudia la generación de estructuras bimodales en polímeros celulares, en particular aquellos con base de polietileno, tratando de hallar los mecanismos físicos por los cuales esta doble distribución de tamaños celulares tiene lugar. Se pretende así comprender el origen de este fenómeno, determinar las condiciones necesarias para que aparezca y a su vez proporcionar un modelo físico sencillo pero a la vez consistente con los resultados experimentales. Para ello, se han fabricado mediante moldeo por compresión mejorado (ICM) espumas a distintas presiones de trabajo (entre 0.5 y 7.5MPa), caracterizándose su estructura celular para tratar de relacionar la producción de estructuras bimodales con la presión. Además, se fabricaron mediante ICM varias muestras más a distintos tiempos de producción y grados de expansión, con objeto de analizar las primeras etapas de la formación de estas estructuras. Los resultados experimentales han permitido probar que este fenómeno se produce por una doble nucleación durante el proceso de fabricación. Asimismo se ha podido relacionar esta doble nucleación con los valores de la presión de trabajo y establecer su dependencia mediante modelos teóricos. Comprender cómo se originan estas estructuras bimodales abre la vía para producirlas ex profeso y estudiar sus propiedades, lo cual supone una estrategia novedosa de fabricación de polímeros celulares que requerirá de nuevos y más amplios estudios.Grado en Físic

Catalogue of exoplanets accessible in reflected starlight to the Nancy Grace Roman Space Telescope. A population study and prospects for phase-curve measurements

Reflected starlight measurements will open a new path in the characterization of directly imaged exoplanets. However, we still lack a population study of known targets amenable to this technique. Here, we investigate which of the about 4300 exoplanets confirmed to date are accessible to the Roman Space Telescope's coronagraph (CGI) in reflected starlight at reference wavelengths $\lambda$=575, 730 and 825 nm. We carry out a population study and also address the prospects for phase-curve measurements. We used the NASA Exoplanet Archive as a reference for planet and star properties, and explored the impact of their uncertainties on the exoplanet's detectability by applying statistical arguments. We define a planet as Roman-accessible on the basis of the instrument inner and outer working angles and its minimum planet-to-star constrast (IWA, OWA, $C_{min}$). We adopt for these technical specifications three plausible configurations labeled as pessimistic, intermediate and optimistic. Our key outputs for each exoplanet are its probability of being Roman-accessible ($P_{access}$), the range of observable phase angles, the evolution of its equilibrium temperature, the number of days per orbit that it is accessible and its transit probability. In the optimistic scenario, we find 26 Roman-accessible exoplanets with $P_{access}$>25% and host stars brighter than $V$=7 mag. This population is biased towards planets more massive than Jupiter but also includes the super-Earths tau Cet e and f which orbit near their star's habitable zone. A total of 13 planets are part of multiplanet systems, 3 of them with known transiting companions, offering opportunities for contemporaneous characterization. The intermediate and pessimistic scenarios yield 10 and 3 Roman-accessible exoplanets, respectively. We find that inclination estimates (e.g. with astrometry) are key for refining the detectability prospects.Comment: Accepted for publication in A&A. 34 pages, 12 Tables, 24 Figure

Diseño y despliegue de un sistema de monitoreo basado en IoT para cultivos hidropónicos

El IoT es tendencia tecnológica que hace posible sistemas inteligentes entre cosas conectadas. Su apli cación se encuentra en diferentes campos, uno de ellos es la agricultura, donde el uso de nuevas técni cas, como la hidroponía, está en auge. Es importante abordar esta área, porque la población mundial alcan zará un aproximado de 9600 millones de habitantes para el 2050, por ende, para satisfacer esta demanda se necesita que el ritmo industrial agrícola sea aún más rápido y preciso. Además, el aumento de la tem peratura ambiente y los cambios climáticos por el calentamiento global también están afectando negati vamente a la producción agraria. En esta investigación se presenta un sistema de monitoreo IoT escalable basado en la tecnología Sigfox con capacidades de predicción del 89,37 % a través de redes neuronales para aplicaciones agrícolas. Se proporciona una ar quitectura efectiva de cuatro capas que consta de percepción, red, middleware y aplicación. Para la validación, el sistema fue construido, probado experi mentalmente y validado mediante el monitoreo de la temperatura, humedad y control de la recirculación de nutrientes, en un sistema hidropónico de la ciudad de Loja en Ecuador, durante cinco meses. El sistema desarrollado es lo suficientemente inteligente para proporcionar la acción de control adecuada para el entorno hidropónico, en función de los múltiples pará metros de entrada recopilados, facilitando una gestión efectiva para los agricultores, por ende, mejorando su producción.//The IoT is a technological trend that enables the application of intelligent systems between connected things. IoT is being applied in different fields, in cluding agriculture, where new techniques such as hydroponics are booming. As the increase in ambient temperature and climate changes caused by global warming have negatively affected agricultural produc tion and the rapid growth of the world’s population, which will reach approximately 9.6 billion by 2050, the industrial pace of agriculture needs to be even faster and more precise. This research presents a scalable IoT monitoring system based on Sigfox technology with 89.37% prediction capabilities through neural networks for agricultural applications. An effective four-layer architecture consisting of perception, net work, middleware, and application is provided. The system was experimentally tested and validated for five months by monitoring temperature, humidity, and nutrient recirculation control in a hydroponic system in Loja, Ecuador. The developed system is smart enough to adequately control the hydroponi cenvironment based on the multiple input parameters collected, facilitating effective management for farm ers and improving production

Direct imaging of cold exoplanets. A theory framework for atmospheric characterization

Upcoming space missions such as WFIRST and under-development concepts like LUVOIR or HabEx will measure the starlight reflected from cold and temperate exoplanets by direct imaging. Reflected starlight is sensitive to atmospheric depths that cannot be probed in transit (e.g. [1]) and provides a means for investigating non-transiting exoplanets. Directly imaged exoplanets observed in reflected starlight represents the next frontier in exoplanet atmospheres characterization. Thus, the theory for planning and interpreting future observations and the physics behind them is now in development [2]. The goal of this work is to understand what information can be extracted from direct imaging observations of exoplanets in reflected starlight and how robust these conclusions are. We computed synthetic spectra for more than 3 million atmospheric configurations that probe a variety of physical properties of the atmosphere. With that, we studied how degeneracies between parameters affect the atmospheric retrieval in direct imaging observations

Diseño y despliegue de un sistema de monitoreo basado en IoT para cultivos hidropónicos

El IoT es tendencia tecnológica que hace posible sistemas inteligentes entre cosas conectadas. Su aplicación se encuentra en diferentes campos, uno de ellos es la agricultura, donde el uso de nuevas técnicas, como la hidroponía, está en auge. Es importante abordar esta área, porque la población mundial alcanzará un aproximado de 9600 millones de habitantes para el 2050, por ende, para satisfacer esta demanda se necesita que el ritmo industrial agrícola sea aún más rápido y preciso. Además, el aumento de la temperatura ambiente y los cambios climáticos por el calentamiento global también están afectando negativamente a la producción agraria. En esta investigación se presenta un sistema de monitoreo IoT escalable basado en la tecnología Sigfox con capacidades de predicción del 89,37 % a través de redes neuronales para aplicaciones agrícolas. Se proporciona una arquitectura efectiva de cuatro capas que consta de percepción, red, middleware y aplicación. Para la validación, el sistema fue construido, probado experimentalmente y validado mediante el monitoreo de la temperatura, humedad y control de la recirculación de nutrientes, en un sistema hidropónico de la ciudad de Loja en Ecuador, durante cinco meses. El sistema desarrollado es lo suficientemente inteligente para proporcionar la acción de control adecuada para el entorno hidropónico, en función de los múltiples parámetros de entrada recopilados, facilitando una gestión efectiva para los agricultores, por ende, mejorando su producción

Comparando la evaluación basada en simulación formativa y sumativa en estudiantes de pregrado en enfermería: adquisición de competencias en enfermería y satisfacción con la simulación clínica

Background Formative and summative evaluation are widely employed in simulated-based assessment. The aims of our study were to evaluate the acquisition of nursing competencies through clinical simulation in undergraduate nursing students and to compare their satisfaction with this methodology using these two evaluation strategies. Methods Two hundred eighteen undergraduate nursing students participated in a cross-sectional study, using a mixed-method. MAES© (self-learning methodology in simulated environments) sessions were developed to assess students by formative evaluation. Objective Structured Clinical Examination sessions were conducted to assess students by summative evaluation. Simulated scenarios recreated clinical cases of critical patients. Students´ performance in all simulated scenarios were assessed using checklists. A validated questionnaire was used to evaluate satisfaction with clinical simulation. Quantitative data were analysed using the IBM SPSS Statistics version 24.0 software, whereas qualitative data were analysed using the ATLAS-ti version 8.0 software. Results Most nursing students showed adequate clinical competence. Satisfaction with clinical simulation was higher when students were assessed using formative evaluation. The main students’ complaints with summative evaluation were related to reduced time for performing simulated scenarios and increased anxiety during their clinical performance. Conclusion The best solution to reduce students’ complaints with summative evaluation is to orient them to the simulated environment. It should be recommended to combine both evaluation strategies in simulated-based assessment, providing students feedback in summative evaluation, as well as evaluating their achievement of learning outcomes in formative evaluation.Depto. de EnfermeríaFac. de Enfermería, Fisioterapia y PodologíaTRUEpu

Doppler wind measurements in Neptune's stratosphere with ALMA

Neptune's tropospheric winds are among the most intense in the Solar System, but the dynamical mechanisms that produce them remain uncertain. Measuring wind speeds at different pressure levels may help understand the atmospheric dynamics of the planet. The goal of this work is to directly measure winds in Neptune's stratosphere with ALMA Doppler spectroscopy. We derived the Doppler lineshift maps of Neptune at the CO(3-2) and HCN(4-3) lines at 345.8 GHz ($\lambda$~0.87 mm) and 354.5 GHz (0.85 mm), respectively. For that, we used spectra obtained with ALMA in 2016 and recorded with a spatial resolution of ~0.37" on Neptune's 2.24" disk. After subtracting the planet solid rotation, we inferred the contribution of zonal winds to the measured Doppler lineshifts at the CO and HCN lines. We developed an MCMC-based retrieval methodology to constrain the latitudinal distribution of wind speeds. We find that CO(3-2) and HCN(4-3) lines probe the stratosphere of Neptune at pressures of $2^{+12}_{-1.8}$ mbar and $0.4^{+0.5}_{-0.3}$ mbar, respectively. The zonal winds at these altitudes are less intense than the tropospheric winds based on cloud tracking from Voyager observations. We find equatorial retrograde (westward) winds of $-180^{+70}_{-60}$ m/s for CO, and $-190^{+90}_{-70}$ m/s for HCN. Wind intensity decreases towards mid-latitudes, and wind speeds at 40$^\circ$S are $-90^{+50}_{-60}$ m/s for CO, and $-40^{+60}_{-80}$ m/s for HCN. Wind speeds become 0 m/s at about 50$^\circ$S, and we find that the circulation reverses to a prograde jet southwards of 60$^\circ$S. Overall, our direct stratospheric wind measurements match previous estimates from stellar occultation profiles and expectations based on thermal wind equilibrium. These are the first direct Doppler wind measurements performed on the Icy Giants, opening a new method to study and monitor their stratospheric dynamics.Comment: Accepted for publication in A&A Letters on 10/05/2023. 8 pages, 1 Table, 5 Figure