Repositorio Institucional UCSC (Univ. Católica de la Santísima Concepción)
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Configuración, naturaleza y extensión de los daños surgida como consecuencia de los daños causados en estado de necesidad
No full textAluminum oxide nanoparticles: Properties and applications overview
No full textAluminum oxide nanoparticles (Al2O3 NPs) have attracted significant attention to various scientific and industrial fields due to their unique bio−/physicochemical properties: high surface area, high hardness, thermal stability, biocompatibility, surface functionalization, and electrical insulation. This chapter exposes the key aspects of Al2O3 NPs synthesis that include sol-gel, hydrothermal, combustion, and green methods. Each method provides control over the particle size, shape, and chemical surface, enabling tailored nanoparticles for specific applications. In catalysis, Al2O3 NPs serve as efficient catalyst supports, enhancing reaction rates and selectivity. Additionally, their remarkable dielectric properties make them valuable for electronic and optoelectronic devices. Moreover, Al2O3 NPs have demonstrated promising results in biomedical applications, including drug delivery systems, biomedical imaging, biosensing, and tissue engineering. Furthermore, recent studies have shown that Al2O3 NPs have potent antimicrobial and antiviral properties. Due to their small size, they can penetrate bacterial and viral cells more effectively, increasing the efficacy of their action. Al2O3 NPs can be incorporated into coatings for medical devices and hospital surfaces, helping prevent bacterial adhesion and biofilm formation, thereby reducing the risk of infections. In addition, Al2O3 NPs have demonstrated potent adjuvant activity for several vaccines throughout history, targeting and neutralizing a wide range of microorganisms. In the future, Al2O3 NPs hold great promise as key components in a wide range of advanced materials and applications, like advanced coatings, energy storage systems, catalysis, biomedical applications, environmental remediation, optoelectronics, photonics, and personal care products
Artificial intelligence and its implication in the development of systematized reviews. Uses and limitations
No full textTransformerless partial power converter topology for electric vehicle fast charge
Get PDFIncreasing the power rating of electric vehicles (EV) fast charging stations to reduce charging times is considered critical to accelerate the adoption of electric vehicles. Besides increasing the power, other drivers pushing the development of EV fast chargers include the improvement of efficiency and reliability. Partial power converters (PPC) have emerged as an interesting option for some of the power converter stages in fast charging stations due to their potential to increase efficiency and power rating. However, some PPCs operate as switched autotransformers by using high frequency (HF) isolation transformers but without providing galvanic isolation. This is a drawback due to cost, size and losses introduced by the transformer. This paper presents a transformerless DC–DC Type I step‐up PPC for a DC–DC regulation converter for EV fast charging stations. The proposed converter replaces the transformer commonly used in Type I PPC by an impedance network, resulting in a more efficient, cheaper, and less complex converter option. This concept is verified through simulations and experimentally validated with a laboratory prototype
The impact of ESG on the default risk of family firms: International evidence
No full textThis research is focused on studying the relationship between ESG performance and default risk of family firms. The sample consists of the 500 largest family firms worldwide (including all continents) for the period 2015–2021. This study shows a positive and a statistically significant relationship between ESG score and Z-score. This is confirmed for ESG environmental and ESG social scores. We include ownership concentration of family members as well as the percentage of family members in the board of directors. In the first case, we detect a non-linear relationship between ownership concentration and Z-score (inverted U shape) and for the second variable we find a negative relationship between the family participation in the board and Z-score. Finally, financial constraints of family firms reduce the impact of ESG score on Z-score
The oil price (Ir)relevance for global CO2 emissions
Get PDFThis study investigates the relationship between oil prices and global CO2 emissions under an instrumental variable research design. In the first stage, we take advantage of the global oil market model developed by Baumeister and Hamilton (2019) to produce exogenous shocks to the oil supply and global economic activity. In the second stage, we use these shocks to compute impulse responses to observed oil prices and CO2 emissions. Finally, based on the latter computations, we obtain the dynamic multiplier that measures the shock-specific effect driving a 1% increase in the oil price on the cumulative CO2 emissions. Our results reveal a nuanced relationship: not all increases in oil prices uniformly lead to a reduction in CO2 emissions. Reductions in CO2 emissions are predominantly observed when increases in oil prices are supply-driven, revealing a substitution effect from fossil fuel to renewable energies in the energy market. However, CO2 emissions increase when oil prices are higher during times with positive shocks to global economic activity
Progress and challenges in the institutionalisation of service-learning at Universidad Católica de la Santísima Concepción of Chile
No full textEste trabajo tiene por objetivo realizar un levantamiento de los avances en la adopción del aprendizaje-servicio en la Universidad Católica de la Santísima Concepción para conocer su nivel de institucionalización y cómo se ha implementado. La metodología incluyó la aplicación de la rúbrica de institucionalización propuesta por Furco y la rúbrica de evaluación de los proyectos de aprendizaje-servicio elaborada por el GREM de la Universidad de Barcelona. La población encuestada incluyó miembros de la Comisión de Aprendizaje-Servicio institucional, docentes que han aplicado la metodología de aprendizaje-servicio, estudiantes y socios comunitarios. Además, se realizaron dos grupos focales para complementar la información obtenida. En la medida que se consolida el aprendizaje-servicio se espera incorporar mecanismos de monitoreo de los avances de su institucionalización y evaluación de la calidad e impacto de los proyectos desarrollados, tanto en la formación de los estudiantes como en las comunidades beneficiadas
A close binary lens revealed by the Microlensing Event Gaia20bof
Get PDFDuring the last 25 yr, hundreds of binary stars and planets have been discovered toward the Galactic bulge by microlensing surveys. Thanks to a new generation of large-sky surveys, it is now possible to regularly detect microlensing events across the entire sky. The OMEGA Key Projet at the Las Cumbres Observatory carries out automated follow-up observations of microlensing events alerted by these surveys with the aim of identifying and characterizing exoplanets as well as stellar remnants. In this study, we present the analysis of the binary lens event Gaia20bof. By automatically requesting additional observations, the OMEGA Key Project obtained dense time coverage of an anomaly near the peak of the event, allowing characterization of the lensing system. The observed anomaly in the lightcurve is due to a binary lens. However, several models can explain the observations. Spectroscopic observations indicate that the source is located at ≤2.0 kpc, in agreement with the parallax measurements from Gaia. While the models are currently degenerate, future observations, especially the Gaia astrometric time series as well as high-resolution imaging, will provide extra constraints to distinguish between them
Didactic baseball teaching strategy for the professional improvement of Sub-12 pitching coaches
Get PDFLa preparación didáctica del entrenador de béisbol, se presenta en la actualidad como un aspecto importante a considerar, debido a la relevancia que adquiere para determinar la calidad de un proceso de entrenamiento eficiente dentro del contexto deportivo actual. Es por ello que se establece como aspecto justificativo en la investigación, determinar las principales insuficiencias que limitan el accionar didáctico de este profesional, y a su vez permite establecer como el objetivo en la investigación diseñar una estrategia para la superación profesional dirigida a la preparación didáctica del entrenador béisbol. En la investigación participa una muestra conformada por 54 entrenadores que trabajan en la categoría sub 12 años pertenecientes a los 17 combinados deportivos enclavados en el municipio Santiago de Cuba. Entre los métodos empleados se encuentra, la observación; el pre-experimento y la encuesta, de los métodos estadísticos se precisó de la estadística descriptiva y la estadística inferencial donde se aplicó la prueba no paramétrica de Wilcoxon. Como resultado se muestra una nueva vía de solución para contribuir al mejoramiento de la preparación didáctica del entrenador de béisbol, a partir de novedosas herramientas que permiten la sistematización del conocimiento de una manera lógica y dinámica, lo cual propiciara una accionar del entrenador con mayor dominio de los recursos que aporta la didáctica, para hacer frente con eficiencia al contexto profesional en el cual participa
Extended kinematical 3D gravity theories
Get PDFIn this work, we classify all extended and generalized kinematical Lie algebras that can be obtained by expanding the so (2, 2) algebra. We show that the Lie algebra expansion method based on semigroups reproduces not only the original kinematical algebras but also a family of non- and ultra-relativistic algebras. Remarkably, the extended kinematical algebras obtained as sequential expansions of the AdS algebra are characterized by a non-degenerate bilinear invariant form, ensuring the construction of a well-defned Chern-Simons gravity action in three spacetime dimensions. Contrary to the contraction process, the degeneracy of the non-Lorentzian theories is avoided without extending the relativistic algebra but considering a bigger semigroup. Using the properties of the expansion procedure, we show that our construction also applies at the level of the Chern-Simons action